diff --git a/.vscode-test.js b/.vscode-test.js index 1e5de54470c..ce539a65721 100644 --- a/.vscode-test.js +++ b/.vscode-test.js @@ -42,6 +42,11 @@ const extensions = [ workspaceFolder: `extensions/vscode-colorize-tests/test`, mocha: { timeout: 60_000 } }, + { + label: 'vscode-colorize-perf-tests', + workspaceFolder: `extensions/vscode-colorize-perf-tests/test`, + mocha: { timeout: 6000_000 } + }, { label: 'configuration-editing', workspaceFolder: path.join(os.tmpdir(), `confeditout-${Math.floor(Math.random() * 100000)}`), diff --git a/.vscode/launch.json b/.vscode/launch.json index b2e25927a8a..1a6be10d6c1 100644 --- a/.vscode/launch.json +++ b/.vscode/launch.json @@ -202,6 +202,24 @@ "order": 5 } }, + { + "type": "extensionHost", + "request": "launch", + "name": "VS Code Tokenizer Performance Tests", + "runtimeExecutable": "${execPath}", + "args": [ + "${workspaceFolder}/extensions/vscode-colorize-perf-tests/test", + "--extensionDevelopmentPath=${workspaceFolder}/extensions/vscode-colorize-perf-tests", + "--extensionTestsPath=${workspaceFolder}/extensions/vscode-colorize-perf-tests/out" + ], + "outFiles": [ + "${workspaceFolder}/out/**/*.js" + ], + "presentation": { + "group": "5_tests", + "order": 6 + } + }, { "type": "chrome", "request": "attach", diff --git a/build/azure-pipelines/darwin/product-build-darwin-test.yml b/build/azure-pipelines/darwin/product-build-darwin-test.yml index 359aa460a59..9e054574c81 100644 --- a/build/azure-pipelines/darwin/product-build-darwin-test.yml +++ b/build/azure-pipelines/darwin/product-build-darwin-test.yml @@ -61,6 +61,7 @@ steps: compile-extension:typescript-language-features \ compile-extension:vscode-api-tests \ compile-extension:vscode-colorize-tests \ + compile-extension:vscode-colorize-perf-tests \ compile-extension:vscode-test-resolver displayName: Build integration tests diff --git a/build/azure-pipelines/linux/product-build-linux-test.yml b/build/azure-pipelines/linux/product-build-linux-test.yml index 5f7381d487c..6796339c738 100644 --- a/build/azure-pipelines/linux/product-build-linux-test.yml +++ b/build/azure-pipelines/linux/product-build-linux-test.yml @@ -80,6 +80,7 @@ steps: compile-extension:typescript-language-features \ compile-extension:vscode-api-tests \ compile-extension:vscode-colorize-tests \ + compile-extension:vscode-colorize-perf-tests \ compile-extension:vscode-test-resolver displayName: Build integration tests diff --git a/build/azure-pipelines/win32/product-build-win32-test.yml b/build/azure-pipelines/win32/product-build-win32-test.yml index cdcccd7684b..09db30d1914 100644 --- a/build/azure-pipelines/win32/product-build-win32-test.yml +++ b/build/azure-pipelines/win32/product-build-win32-test.yml @@ -63,6 +63,7 @@ steps: compile-extension:typescript-language-features ` compile-extension:vscode-api-tests ` compile-extension:vscode-colorize-tests ` + compile-extension:vscode-colorize-perf-tests ` compile-extension:vscode-test-resolver ` } displayName: Build integration tests diff --git a/build/gulpfile.extensions.js b/build/gulpfile.extensions.js index 4f745aebdc7..6b8ca04e809 100644 --- a/build/gulpfile.extensions.js +++ b/build/gulpfile.extensions.js @@ -65,6 +65,7 @@ const compilations = [ 'extensions/typescript-language-features/tsconfig.json', 'extensions/vscode-api-tests/tsconfig.json', 'extensions/vscode-colorize-tests/tsconfig.json', + 'extensions/vscode-colorize-perf-tests/tsconfig.json', 'extensions/vscode-test-resolver/tsconfig.json', '.vscode/extensions/vscode-selfhost-test-provider/tsconfig.json', diff --git a/build/lib/extensions.js b/build/lib/extensions.js index fbf11ee1ee4..c6d56319c30 100644 --- a/build/lib/extensions.js +++ b/build/lib/extensions.js @@ -246,6 +246,7 @@ function fromGithub({ name, version, repo, sha256, metadata }) { const excludedExtensions = [ 'vscode-api-tests', 'vscode-colorize-tests', + 'vscode-colorize-perf-tests', 'vscode-test-resolver', 'ms-vscode.node-debug', 'ms-vscode.node-debug2', diff --git a/build/lib/extensions.ts b/build/lib/extensions.ts index 628cf90c4c9..2a9a215c5e4 100644 --- a/build/lib/extensions.ts +++ b/build/lib/extensions.ts @@ -278,6 +278,7 @@ export function fromGithub({ name, version, repo, sha256, metadata }: IExtension const excludedExtensions = [ 'vscode-api-tests', 'vscode-colorize-tests', + 'vscode-colorize-perf-tests', 'vscode-test-resolver', 'ms-vscode.node-debug', 'ms-vscode.node-debug2', diff --git a/build/npm/dirs.js b/build/npm/dirs.js index b9645e6e137..9f653c72479 100644 --- a/build/npm/dirs.js +++ b/build/npm/dirs.js @@ -44,6 +44,7 @@ const dirs = [ 'extensions/typescript-language-features', 'extensions/vscode-api-tests', 'extensions/vscode-colorize-tests', + 'extensions/vscode-colorize-perf-tests', 'extensions/vscode-test-resolver', 'remote', 'remote/web', diff --git a/extensions/vscode-colorize-perf-tests/.gitignore b/extensions/vscode-colorize-perf-tests/.gitignore new file mode 100644 index 00000000000..8e5962ee727 --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/.gitignore @@ -0,0 +1,2 @@ +out +node_modules \ No newline at end of file diff --git a/extensions/vscode-colorize-perf-tests/.npmrc b/extensions/vscode-colorize-perf-tests/.npmrc new file mode 100644 index 00000000000..a9c57709666 --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/.npmrc @@ -0,0 +1,2 @@ +legacy-peer-deps="true" +timeout=180000 diff --git a/extensions/vscode-colorize-perf-tests/.vscode/launch.json b/extensions/vscode-colorize-perf-tests/.vscode/launch.json new file mode 100644 index 00000000000..73c3753c75c --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/.vscode/launch.json @@ -0,0 +1,17 @@ +// A launch configuration that compiles the extension and then opens it inside a new window +{ + "version": "0.1.0", + "configurations": [ + { + "name": "Launch Tests", + "type": "extensionHost", + "request": "launch", + "runtimeExecutable": "${execPath}", + "args": ["${workspaceFolder}/../../", "${workspaceFolder}/test", "--extensionDevelopmentPath=${workspaceFolder}", "--extensionTestsPath=${workspaceFolder}/out" ], + "stopOnEntry": false, + "sourceMaps": true, + "outDir": "${workspaceFolder}/out", + "preLaunchTask": "npm" + } + ] +} \ No newline at end of file diff --git a/extensions/vscode-colorize-perf-tests/.vscode/tasks.json b/extensions/vscode-colorize-perf-tests/.vscode/tasks.json new file mode 100644 index 00000000000..390a93a3a7f --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/.vscode/tasks.json @@ -0,0 +1,11 @@ +{ + "version": "2.0.0", + "command": "npm", + "type": "shell", + "presentation": { + "reveal": "silent" + }, + "args": ["run", "compile"], + "isBackground": true, + "problemMatcher": "$tsc-watch" +} diff --git a/extensions/vscode-colorize-perf-tests/media/icon.png b/extensions/vscode-colorize-perf-tests/media/icon.png new file mode 100644 index 00000000000..f785ef70316 Binary files /dev/null and b/extensions/vscode-colorize-perf-tests/media/icon.png differ diff --git a/extensions/vscode-colorize-perf-tests/package-lock.json b/extensions/vscode-colorize-perf-tests/package-lock.json new file mode 100644 index 00000000000..b0516cc1e28 --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/package-lock.json @@ -0,0 +1,42 @@ +{ + "name": "vscode-colorize-perf-tests", + "version": "0.0.1", + "lockfileVersion": 3, + "requires": true, + "packages": { + "": { + "name": "vscode-colorize-perf-tests", + "version": "0.0.1", + "license": "MIT", + "dependencies": { + "jsonc-parser": "^3.2.0" + }, + "devDependencies": { + "@types/node": "20.x" + }, + "engines": { + "vscode": "*" + } + }, + "node_modules/@types/node": { + "version": "20.11.24", + "resolved": "https://registry.npmjs.org/@types/node/-/node-20.11.24.tgz", + "integrity": "sha512-Kza43ewS3xoLgCEpQrsT+xRo/EJej1y0kVYGiLFE1NEODXGzTfwiC6tXTLMQskn1X4/Rjlh0MQUvx9W+L9long==", + "dev": true, + "dependencies": { + "undici-types": "~5.26.4" + } + }, + "node_modules/jsonc-parser": { + "version": "3.2.0", + "resolved": "https://registry.npmjs.org/jsonc-parser/-/jsonc-parser-3.2.0.tgz", + "integrity": "sha512-gfFQZrcTc8CnKXp6Y4/CBT3fTc0OVuDofpre4aEeEpSBPV5X5v4+Vmx+8snU7RLPrNHPKSgLxGo9YuQzz20o+w==" + }, + "node_modules/undici-types": { + "version": "5.26.5", + "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-5.26.5.tgz", + "integrity": "sha512-JlCMO+ehdEIKqlFxk6IfVoAUVmgz7cU7zD/h9XZ0qzeosSHmUJVOzSQvvYSYWXkFXC+IfLKSIffhv0sVZup6pA==", + "dev": true + } + } +} diff --git a/extensions/vscode-colorize-perf-tests/package.json b/extensions/vscode-colorize-perf-tests/package.json new file mode 100644 index 00000000000..2e72152e284 --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/package.json @@ -0,0 +1,31 @@ +{ + "name": "vscode-colorize-perf-tests", + "description": "Colorize performance tests for VS Code", + "version": "0.0.1", + "publisher": "vscode", + "license": "MIT", + "private": true, + "activationEvents": [ + "onLanguage:json" + ], + "main": "./out/colorizerTestMain", + "engines": { + "vscode": "*" + }, + "icon": "media/icon.png", + "scripts": { + "vscode:prepublish": "node ../../node_modules/gulp/bin/gulp.js --gulpfile ../../build/gulpfile.extensions.js compile-extension:vscode-colorize-perf-tests ./tsconfig.json", + "watch": "gulp watch-extension:vscode-colorize-perf-tests", + "compile": "gulp compile-extension:vscode-colorize-perf-tests" + }, + "dependencies": { + "jsonc-parser": "^3.2.0" + }, + "devDependencies": { + "@types/node": "20.x" + }, + "repository": { + "type": "git", + "url": "https://github.com/microsoft/vscode.git" + } +} diff --git a/extensions/vscode-colorize-perf-tests/src/colorizer.test.ts b/extensions/vscode-colorize-perf-tests/src/colorizer.test.ts new file mode 100644 index 00000000000..7e1df20ca29 --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/src/colorizer.test.ts @@ -0,0 +1,146 @@ +/*--------------------------------------------------------------------------------------------- + * Copyright (c) Microsoft Corporation. All rights reserved. + * Licensed under the MIT License. See License.txt in the project root for license information. + *--------------------------------------------------------------------------------------------*/ + +import * as fs from 'fs'; +import 'mocha'; +import { basename, join, normalize } from 'path'; +import { commands, ConfigurationTarget, Uri, workspace } from 'vscode'; + +interface BestsAndWorsts { + bestParse?: number; + bestCapture?: number; + bestMetadata?: number; + bestCombined: number; + worstParse?: number; + worstCapture?: number; + worstMetadata?: number; + worstCombined: number; +} + +function findBestsAndWorsts(results: { parseTime?: number; captureTime?: number; metadataTime?: number; tokenizeTime?: number }[]): BestsAndWorsts { + let bestParse: number | undefined; + let bestCapture: number | undefined; + let bestMetadata: number | undefined; + let bestCombined: number | undefined; + let worstParse: number | undefined; + let worstCapture: number | undefined; + let worstMetadata: number | undefined; + let worstCombined: number | undefined; + + for (let i = 0; i < results.length; i++) { + const result = results[i]; + if (result.parseTime && result.captureTime && result.metadataTime) { + // Tree Sitter + const combined = result.parseTime + result.captureTime + result.metadataTime; + if (bestParse === undefined || result.parseTime < bestParse) { + bestParse = result.parseTime; + } + if (bestCapture === undefined || result.captureTime < bestCapture) { + bestCapture = result.captureTime; + } + if (bestMetadata === undefined || result.metadataTime < bestMetadata) { + bestMetadata = result.metadataTime; + } + if (bestCombined === undefined || combined < bestCombined) { + bestCombined = combined; + } + if (i !== 0) { + if (worstParse === undefined || result.parseTime > worstParse) { + worstParse = result.parseTime; + } + if (worstCapture === undefined || result.captureTime > worstCapture) { + worstCapture = result.captureTime; + } + if (worstMetadata === undefined || result.metadataTime > worstMetadata) { + worstMetadata = result.metadataTime; + } + if (worstCombined === undefined || combined > worstCombined) { + worstCombined = combined; + } + } + } else if (result.tokenizeTime) { + // TextMate + if (bestCombined === undefined || result.tokenizeTime < bestCombined) { + bestCombined = result.tokenizeTime; + } + if (i !== 0 && (worstCombined === undefined || result.tokenizeTime > worstCombined)) { + worstCombined = result.tokenizeTime; + } + } + } + return { + bestParse, + bestCapture, + bestMetadata, + bestCombined: bestCombined!, + worstParse, + worstCapture, + worstMetadata, + worstCombined: worstCombined!, + }; +} + +interface TreeSitterTimes { + parseTime: number; + captureTime: number; + metadataTime: number; +} + +interface TextMateTimes { + tokenizeTime: number; +} + +async function runCommand(command: string, file: Uri, times: number): Promise { + const results: TimesType[] = []; + for (let i = 0; i < times; i++) { + results.push(await commands.executeCommand(command, file)); + } + return results; +} + +async function doTest(file: Uri, times: number) { + const treeSitterResults = await runCommand('_workbench.colorizeTreeSitterTokens', file, times); + + const { bestParse, bestCapture, bestMetadata, bestCombined, worstParse, worstCapture, worstMetadata, worstCombined } = findBestsAndWorsts(treeSitterResults); + const textMateResults = await runCommand('_workbench.colorizeTextMateTokens', file, times); + const textMateBestWorst = findBestsAndWorsts(textMateResults); + + const toString = (time: number, charLength: number) => { + // truncate time to charLength characters + return time.toString().slice(0, charLength).padEnd(charLength, ' '); + }; + const numLength = 7; + const resultString = ` | First | Best | Worst | +| --------------------- | ------- | ------- | ------- | +| TreeSitter (parse) | ${toString(treeSitterResults[0].parseTime, numLength)} | ${toString(bestParse!, numLength)} | ${toString(worstParse!, numLength)} | +| TreeSitter (capture) | ${toString(treeSitterResults[0].captureTime, numLength)} | ${toString(bestCapture!, numLength)} | ${toString(worstCapture!, numLength)} | +| TreeSitter (metadata) | ${toString(treeSitterResults[0].metadataTime, numLength)} | ${toString(bestMetadata!, numLength)} | ${toString(worstMetadata!, numLength)} | +| TreeSitter (total) | ${toString(treeSitterResults[0].parseTime + treeSitterResults[0].captureTime + treeSitterResults[0].metadataTime, numLength)} | ${toString(bestCombined, numLength)} | ${toString(worstCombined, numLength)} | +| TextMate | ${toString(textMateResults[0].tokenizeTime, numLength)} | ${toString(textMateBestWorst.bestCombined, numLength)} | ${toString(textMateBestWorst.worstCombined, numLength)} | +`; + console.log(`File ${basename(file.fsPath)}:`); + console.log(resultString); +} + +suite('Tokenization Performance', () => { + const testPath = normalize(join(__dirname, '../test')); + const fixturesPath = join(testPath, 'colorize-fixtures'); + let originalSettingValue: any; + + suiteSetup(async function () { + originalSettingValue = workspace.getConfiguration('editor').get('experimental.preferTreeSitter'); + await workspace.getConfiguration('editor').update('experimental.preferTreeSitter', ["typescript"], ConfigurationTarget.Global); + }); + suiteTeardown(async function () { + await workspace.getConfiguration('editor').update('experimental.preferTreeSitter', originalSettingValue, ConfigurationTarget.Global); + }); + + for (const fixture of fs.readdirSync(fixturesPath)) { + test(`Full file colorize: ${fixture}`, async function () { + await commands.executeCommand('workbench.action.closeAllEditors'); + await doTest(Uri.file(join(fixturesPath, fixture)), 6); + }); + } +}); diff --git a/extensions/vscode-colorize-perf-tests/src/colorizerTestMain.ts b/extensions/vscode-colorize-perf-tests/src/colorizerTestMain.ts new file mode 100644 index 00000000000..3508834f8c6 --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/src/colorizerTestMain.ts @@ -0,0 +1,10 @@ +/*--------------------------------------------------------------------------------------------- + * Copyright (c) Microsoft Corporation. All rights reserved. + * Licensed under the MIT License. See License.txt in the project root for license information. + *--------------------------------------------------------------------------------------------*/ + +import * as vscode from 'vscode'; + +export function activate(_context: vscode.ExtensionContext): any { + +} diff --git a/extensions/vscode-colorize-perf-tests/src/index.ts b/extensions/vscode-colorize-perf-tests/src/index.ts new file mode 100644 index 00000000000..4376f31accd --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/src/index.ts @@ -0,0 +1,30 @@ +/*--------------------------------------------------------------------------------------------- + * Copyright (c) Microsoft Corporation. All rights reserved. + * Licensed under the MIT License. See License.txt in the project root for license information. + *--------------------------------------------------------------------------------------------*/ + +import * as path from 'path'; +import * as testRunner from '../../../test/integration/electron/testrunner'; + +const suite = 'Performance Colorize Tests'; + +const options: import('mocha').MochaOptions = { + ui: 'tdd', + color: true, + timeout: 60000 +}; + +if (process.env.BUILD_ARTIFACTSTAGINGDIRECTORY) { + options.reporter = 'mocha-multi-reporters'; + options.reporterOptions = { + reporterEnabled: 'spec, mocha-junit-reporter', + mochaJunitReporterReporterOptions: { + testsuitesTitle: `${suite} ${process.platform}`, + mochaFile: path.join(process.env.BUILD_ARTIFACTSTAGINGDIRECTORY, `test-results/${process.platform}-${process.arch}-${suite.toLowerCase().replace(/[^\w]/g, '-')}-results.xml`) + } + }; +} + +testRunner.configure(options); + +export = testRunner; diff --git a/extensions/vscode-colorize-perf-tests/test/colorize-fixtures/test-checker.ts b/extensions/vscode-colorize-perf-tests/test/colorize-fixtures/test-checker.ts new file mode 100644 index 00000000000..ace6bd2a57b --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/test/colorize-fixtures/test-checker.ts @@ -0,0 +1,146620 @@ +// Copied from https://github.com/microsoft/TypeScript for running tests against a large file + +import { + __String, + AccessExpression, + AccessFlags, + AccessorDeclaration, + addRange, + addRelatedInfo, + addSyntheticLeadingComment, + AliasDeclarationNode, + AllAccessorDeclarations, + AmbientModuleDeclaration, + and, + AnonymousType, + AnyImportOrJsDocImport, + AnyImportOrReExport, + append, + appendIfUnique, + ArrayBindingPattern, + arrayFrom, + arrayIsHomogeneous, + ArrayLiteralExpression, + arrayOf, + arraysEqual, + arrayToMultiMap, + ArrayTypeNode, + ArrowFunction, + AsExpression, + AssertionExpression, + AssignmentDeclarationKind, + AssignmentKind, + AssignmentPattern, + AwaitExpression, + BaseType, + BigIntLiteral, + BigIntLiteralType, + BinaryExpression, + BinaryOperator, + BinaryOperatorToken, + binarySearch, + BindableObjectDefinePropertyCall, + BindableStaticNameExpression, + BindingElement, + BindingElementGrandparent, + BindingName, + BindingPattern, + bindSourceFile, + Block, + BooleanLiteral, + BreakOrContinueStatement, + CallChain, + CallExpression, + CallLikeExpression, + CallSignatureDeclaration, + CancellationToken, + canHaveDecorators, + canHaveExportModifier, + canHaveFlowNode, + canHaveIllegalDecorators, + canHaveIllegalModifiers, + canHaveJSDoc, + canHaveLocals, + canHaveModifiers, + canHaveSymbol, + canIncludeBindAndCheckDiagnostics, + canUsePropertyAccess, + cartesianProduct, + CaseBlock, + CaseClause, + CaseOrDefaultClause, + cast, + chainDiagnosticMessages, + CharacterCodes, + CheckFlags, + ClassDeclaration, + ClassElement, + classElementOrClassElementParameterIsDecorated, + ClassExpression, + ClassLikeDeclaration, + classOrConstructorParameterIsDecorated, + ClassStaticBlockDeclaration, + clear, + combinePaths, + compareDiagnostics, + comparePaths, + compareValues, + Comparison, + CompilerOptions, + ComputedPropertyName, + concatenate, + concatenateDiagnosticMessageChains, + ConditionalExpression, + ConditionalRoot, + ConditionalType, + ConditionalTypeNode, + ConstructorDeclaration, + ConstructorTypeNode, + ConstructSignatureDeclaration, + contains, + containsParseError, + ContextFlags, + copyEntries, + countWhere, + createBinaryExpressionTrampoline, + createCompilerDiagnostic, + createDetachedDiagnostic, + createDiagnosticCollection, + createDiagnosticForFileFromMessageChain, + createDiagnosticForNode, + createDiagnosticForNodeArray, + createDiagnosticForNodeArrayFromMessageChain, + createDiagnosticForNodeFromMessageChain, + createDiagnosticMessageChainFromDiagnostic, + createEmptyExports, + createEvaluator, + createFileDiagnostic, + createFlowNode, + createGetSymbolWalker, + createModeAwareCacheKey, + createModuleNotFoundChain, + createMultiMap, + createNameResolver, + createPrinterWithDefaults, + createPrinterWithRemoveComments, + createPrinterWithRemoveCommentsNeverAsciiEscape, + createPrinterWithRemoveCommentsOmitTrailingSemicolon, + createPropertyNameNodeForIdentifierOrLiteral, + createScanner, + createSymbolTable, + createSyntacticTypeNodeBuilder, + createTextWriter, + Debug, + Declaration, + DeclarationName, + declarationNameToString, + DeclarationStatement, + DeclarationWithTypeParameterChildren, + DeclarationWithTypeParameters, + Decorator, + deduplicate, + DefaultClause, + defaultMaximumTruncationLength, + DeferredTypeReference, + DeleteExpression, + Diagnostic, + DiagnosticAndArguments, + DiagnosticArguments, + DiagnosticCategory, + DiagnosticMessage, + DiagnosticMessageChain, + DiagnosticRelatedInformation, + Diagnostics, + DiagnosticWithLocation, + DoStatement, + DynamicNamedDeclaration, + ElementAccessChain, + ElementAccessExpression, + ElementFlags, + EmitFlags, + EmitHint, + emitModuleKindIsNonNodeESM, + EmitResolver, + EmitTextWriter, + emptyArray, + endsWith, + EntityName, + EntityNameExpression, + EntityNameOrEntityNameExpression, + entityNameToString, + EnumDeclaration, + EnumMember, + EnumType, + equateValues, + escapeLeadingUnderscores, + escapeString, + EvaluatorResult, + evaluatorResult, + every, + EvolvingArrayType, + ExclamationToken, + ExportAssignment, + exportAssignmentIsAlias, + ExportDeclaration, + ExportSpecifier, + Expression, + expressionResultIsUnused, + ExpressionStatement, + ExpressionWithTypeArguments, + Extension, + ExternalEmitHelpers, + externalHelpersModuleNameText, + factory, + fileExtensionIs, + fileExtensionIsOneOf, + filter, + find, + findAncestor, + findBestPatternMatch, + findConstructorDeclaration, + findIndex, + findLast, + findLastIndex, + findUseStrictPrologue, + first, + firstDefined, + firstIterator, + firstOrUndefined, + firstOrUndefinedIterator, + flatMap, + flatten, + FlowArrayMutation, + FlowAssignment, + FlowCall, + FlowCondition, + FlowFlags, + FlowLabel, + FlowNode, + FlowReduceLabel, + FlowStart, + FlowSwitchClause, + FlowSwitchClauseData, + FlowType, + forEach, + forEachChild, + forEachChildRecursively, + forEachEnclosingBlockScopeContainer, + forEachEntry, + forEachKey, + forEachReturnStatement, + forEachYieldExpression, + ForInOrOfStatement, + ForInStatement, + formatMessage, + ForOfStatement, + ForStatement, + FreshableIntrinsicType, + FreshableType, + FreshObjectLiteralType, + FunctionDeclaration, + FunctionExpression, + FunctionFlags, + FunctionLikeDeclaration, + FunctionOrConstructorTypeNode, + FunctionTypeNode, + GenericType, + GetAccessorDeclaration, + getAliasDeclarationFromName, + getAllJSDocTags, + getAllowSyntheticDefaultImports, + getAncestor, + getAssignedExpandoInitializer, + getAssignmentDeclarationKind, + getAssignmentDeclarationPropertyAccessKind, + getAssignmentTargetKind, + getCanonicalDiagnostic, + getCheckFlags, + getClassExtendsHeritageElement, + getClassLikeDeclarationOfSymbol, + getCombinedLocalAndExportSymbolFlags, + getCombinedModifierFlags, + getCombinedNodeFlags, + getContainingClass, + getContainingClassExcludingClassDecorators, + getContainingClassStaticBlock, + getContainingFunction, + getContainingFunctionOrClassStaticBlock, + getDeclarationModifierFlagsFromSymbol, + getDeclarationOfKind, + getDeclarationsOfKind, + getDeclaredExpandoInitializer, + getDecorators, + getDirectoryPath, + getEffectiveBaseTypeNode, + getEffectiveConstraintOfTypeParameter, + getEffectiveContainerForJSDocTemplateTag, + getEffectiveImplementsTypeNodes, + getEffectiveInitializer, + getEffectiveJSDocHost, + getEffectiveModifierFlags, + getEffectiveReturnTypeNode, + getEffectiveSetAccessorTypeAnnotationNode, + getEffectiveTypeAnnotationNode, + getEffectiveTypeParameterDeclarations, + getElementOrPropertyAccessName, + getEmitDeclarations, + getEmitFlags, + getEmitModuleKind, + getEmitModuleResolutionKind, + getEmitScriptTarget, + getEmitStandardClassFields, + getEnclosingBlockScopeContainer, + getEnclosingContainer, + getEntityNameFromTypeNode, + getErrorSpanForNode, + getEscapedTextOfIdentifierOrLiteral, + getEscapedTextOfJsxAttributeName, + getEscapedTextOfJsxNamespacedName, + getESModuleInterop, + getExpandoInitializer, + getExportAssignmentExpression, + getExternalModuleImportEqualsDeclarationExpression, + getExternalModuleName, + getExternalModuleRequireArgument, + getFirstConstructorWithBody, + getFirstIdentifier, + getFunctionFlags, + getHostSignatureFromJSDoc, + getIdentifierGeneratedImportReference, + getIdentifierTypeArguments, + getImmediatelyInvokedFunctionExpression, + getInitializerOfBinaryExpression, + getInterfaceBaseTypeNodes, + getInvokedExpression, + getIsolatedModules, + getJSDocClassTag, + getJSDocDeprecatedTag, + getJSDocEnumTag, + getJSDocHost, + getJSDocOverloadTags, + getJSDocParameterTags, + getJSDocRoot, + getJSDocSatisfiesExpressionType, + getJSDocTags, + getJSDocThisTag, + getJSDocType, + getJSDocTypeAssertionType, + getJSDocTypeParameterDeclarations, + getJSDocTypeTag, + getJSXImplicitImportBase, + getJSXRuntimeImport, + getJSXTransformEnabled, + getLeftmostAccessExpression, + getLineAndCharacterOfPosition, + getMembersOfDeclaration, + getModifiers, + getModuleInstanceState, + getNameFromImportAttribute, + getNameFromIndexInfo, + getNameOfDeclaration, + getNameOfExpando, + getNamespaceDeclarationNode, + getNewTargetContainer, + getNonAugmentationDeclaration, + getNormalizedAbsolutePath, + getObjectFlags, + getOriginalNode, + getOrUpdate, + getParameterSymbolFromJSDoc, + getParseTreeNode, + getPropertyAssignmentAliasLikeExpression, + getPropertyNameForPropertyNameNode, + getPropertyNameFromType, + getResolutionDiagnostic, + getResolutionModeOverride, + getResolveJsonModule, + getRestParameterElementType, + getRootDeclaration, + getScriptTargetFeatures, + getSelectedEffectiveModifierFlags, + getSemanticJsxChildren, + getSetAccessorValueParameter, + getSingleVariableOfVariableStatement, + getSourceFileOfModule, + getSourceFileOfNode, + getSpanOfTokenAtPosition, + getSpellingSuggestion, + getStrictOptionValue, + getSuperContainer, + getSymbolNameForPrivateIdentifier, + getTextOfIdentifierOrLiteral, + getTextOfJSDocComment, + getTextOfJsxAttributeName, + getTextOfNode, + getTextOfPropertyName, + getThisContainer, + getThisParameter, + getTrailingSemicolonDeferringWriter, + getTypeParameterFromJsDoc, + getUseDefineForClassFields, + group, + hasAbstractModifier, + hasAccessorModifier, + hasAmbientModifier, + hasContextSensitiveParameters, + HasDecorators, + hasDecorators, + hasDynamicName, + hasEffectiveModifier, + hasEffectiveModifiers, + hasEffectiveReadonlyModifier, + HasExpressionInitializer, + hasExtension, + HasIllegalDecorators, + HasIllegalModifiers, + hasInferredType, + HasInitializer, + hasInitializer, + hasJSDocNodes, + hasJSDocParameterTags, + hasJsonModuleEmitEnabled, + HasLocals, + HasModifiers, + hasOnlyExpressionInitializer, + hasOverrideModifier, + hasPossibleExternalModuleReference, + hasQuestionToken, + hasResolutionModeOverride, + hasRestParameter, + hasScopeMarker, + hasStaticModifier, + hasSyntacticModifier, + hasSyntacticModifiers, + hasType, + HeritageClause, + Identifier, + identifierToKeywordKind, + IdentifierTypePredicate, + idText, + IfStatement, + ImportAttribute, + ImportAttributes, + ImportCall, + ImportClause, + ImportDeclaration, + ImportEqualsDeclaration, + ImportOrExportSpecifier, + ImportSpecifier, + ImportTypeNode, + IndexedAccessType, + IndexedAccessTypeNode, + IndexFlags, + IndexInfo, + IndexKind, + indexOfNode, + IndexSignatureDeclaration, + IndexType, + indicesOf, + InferenceContext, + InferenceFlags, + InferenceInfo, + InferencePriority, + InferTypeNode, + InstanceofExpression, + InstantiableType, + InstantiationExpressionType, + InterfaceDeclaration, + InterfaceType, + InterfaceTypeWithDeclaredMembers, + InternalSymbolName, + IntersectionFlags, + IntersectionType, + IntersectionTypeNode, + intrinsicTagNameToString, + IntrinsicType, + introducesArgumentsExoticObject, + isAccessExpression, + isAccessor, + isAliasableExpression, + isAmbientModule, + isArray, + isArrayBindingPattern, + isArrayLiteralExpression, + isArrowFunction, + isAssertionExpression, + isAssignmentDeclaration, + isAssignmentExpression, + isAssignmentOperator, + isAssignmentPattern, + isAssignmentTarget, + isAutoAccessorPropertyDeclaration, + isAwaitExpression, + isBinaryExpression, + isBindableObjectDefinePropertyCall, + isBindableStaticElementAccessExpression, + isBindableStaticNameExpression, + isBindingElement, + isBindingElementOfBareOrAccessedRequire, + isBindingPattern, + isBlock, + isBlockOrCatchScoped, + isBlockScopedContainerTopLevel, + isBooleanLiteral, + isCallChain, + isCallExpression, + isCallLikeExpression, + isCallLikeOrFunctionLikeExpression, + isCallOrNewExpression, + isCallSignatureDeclaration, + isCatchClause, + isCatchClauseVariableDeclaration, + isCatchClauseVariableDeclarationOrBindingElement, + isCheckJsEnabledForFile, + isClassDeclaration, + isClassElement, + isClassExpression, + isClassInstanceProperty, + isClassLike, + isClassStaticBlockDeclaration, + isCommaSequence, + isCommonJsExportedExpression, + isCommonJsExportPropertyAssignment, + isCompoundAssignment, + isComputedNonLiteralName, + isComputedPropertyName, + isConditionalTypeNode, + isConstAssertion, + isConstructorDeclaration, + isConstructorTypeNode, + isConstructSignatureDeclaration, + isConstTypeReference, + isDeclaration, + isDeclarationFileName, + isDeclarationName, + isDeclarationReadonly, + isDecorator, + isDefaultedExpandoInitializer, + isDeleteTarget, + isDottedName, + isDynamicName, + isEffectiveExternalModule, + isElementAccessExpression, + isEntityName, + isEntityNameExpression, + isEnumConst, + isEnumDeclaration, + isEnumMember, + isExclusivelyTypeOnlyImportOrExport, + isExpandoPropertyDeclaration, + isExportAssignment, + isExportDeclaration, + isExportsIdentifier, + isExportSpecifier, + isExpression, + isExpressionNode, + isExpressionOfOptionalChainRoot, + isExpressionStatement, + isExpressionWithTypeArguments, + isExpressionWithTypeArgumentsInClassExtendsClause, + isExternalModule, + isExternalModuleAugmentation, + isExternalModuleImportEqualsDeclaration, + isExternalModuleIndicator, + isExternalModuleNameRelative, + isExternalModuleReference, + isExternalModuleSymbol, + isExternalOrCommonJsModule, + isForInOrOfStatement, + isForInStatement, + isForOfStatement, + isForStatement, + isFunctionDeclaration, + isFunctionExpression, + isFunctionExpressionOrArrowFunction, + isFunctionLike, + isFunctionLikeDeclaration, + isFunctionLikeOrClassStaticBlockDeclaration, + isFunctionOrModuleBlock, + isFunctionTypeNode, + isGeneratedIdentifier, + isGetAccessor, + isGetAccessorDeclaration, + isGetOrSetAccessorDeclaration, + isGlobalScopeAugmentation, + isGlobalSourceFile, + isHeritageClause, + isIdentifier, + isIdentifierText, + isIdentifierTypePredicate, + isIdentifierTypeReference, + isIfStatement, + isImportAttributes, + isImportCall, + isImportClause, + isImportDeclaration, + isImportEqualsDeclaration, + isImportKeyword, + isImportOrExportSpecifier, + isImportSpecifier, + isImportTypeNode, + isInCompoundLikeAssignment, + isIndexedAccessTypeNode, + isInExpressionContext, + isInfinityOrNaNString, + isInitializedProperty, + isInJSDoc, + isInJSFile, + isInJsonFile, + isInstanceOfExpression, + isInterfaceDeclaration, + isInternalModuleImportEqualsDeclaration, + isInTopLevelContext, + isIntrinsicJsxName, + isInTypeQuery, + isIterationStatement, + isJSDocAllType, + isJSDocAugmentsTag, + isJSDocCallbackTag, + isJSDocConstructSignature, + isJSDocFunctionType, + isJSDocImportTag, + isJSDocIndexSignature, + isJSDocLinkLike, + isJSDocMemberName, + isJSDocNameReference, + isJSDocNode, + isJSDocNonNullableType, + isJSDocNullableType, + isJSDocOptionalParameter, + isJSDocOptionalType, + isJSDocOverloadTag, + isJSDocParameterTag, + isJSDocPropertyLikeTag, + isJSDocPropertyTag, + isJSDocSatisfiesExpression, + isJSDocSatisfiesTag, + isJSDocSignature, + isJSDocTemplateTag, + isJSDocThisTag, + isJSDocTypeAlias, + isJSDocTypeAssertion, + isJSDocTypedefTag, + isJSDocTypeExpression, + isJSDocTypeLiteral, + isJSDocUnknownType, + isJSDocVariadicType, + isJsonSourceFile, + isJsxAttribute, + isJsxAttributeLike, + isJsxAttributes, + isJsxElement, + isJsxNamespacedName, + isJsxOpeningElement, + isJsxOpeningFragment, + isJsxOpeningLikeElement, + isJsxSelfClosingElement, + isJsxSpreadAttribute, + isJSXTagName, + isKnownSymbol, + isLateVisibilityPaintedStatement, + isLeftHandSideExpression, + isLineBreak, + isLiteralComputedPropertyDeclarationName, + isLiteralExpression, + isLiteralExpressionOfObject, + isLiteralImportTypeNode, + isLiteralTypeNode, + isLogicalOrCoalescingBinaryExpression, + isLogicalOrCoalescingBinaryOperator, + isMappedTypeNode, + isMetaProperty, + isMethodDeclaration, + isMethodSignature, + isModifier, + isModuleBlock, + isModuleDeclaration, + isModuleExportsAccessExpression, + isModuleIdentifier, + isModuleOrEnumDeclaration, + isModuleWithStringLiteralName, + isNamedDeclaration, + isNamedEvaluationSource, + isNamedExports, + isNamedTupleMember, + isNamespaceExport, + isNamespaceExportDeclaration, + isNamespaceReexportDeclaration, + isNewExpression, + isNodeDescendantOf, + isNonNullAccess, + isNonNullExpression, + isNumericLiteral, + isNumericLiteralName, + isObjectBindingPattern, + isObjectLiteralElementLike, + isObjectLiteralExpression, + isObjectLiteralMethod, + isObjectLiteralOrClassExpressionMethodOrAccessor, + isOmittedExpression, + isOptionalChain, + isOptionalChainRoot, + isOptionalDeclaration, + isOptionalJSDocPropertyLikeTag, + isOptionalTypeNode, + isOutermostOptionalChain, + isParameter, + isParameterPropertyDeclaration, + isParenthesizedExpression, + isParenthesizedTypeNode, + isPartOfParameterDeclaration, + isPartOfTypeNode, + isPartOfTypeQuery, + isPlainJsFile, + isPrefixUnaryExpression, + isPrivateIdentifier, + isPrivateIdentifierClassElementDeclaration, + isPrivateIdentifierPropertyAccessExpression, + isPropertyAccessEntityNameExpression, + isPropertyAccessExpression, + isPropertyAccessOrQualifiedName, + isPropertyAccessOrQualifiedNameOrImportTypeNode, + isPropertyAssignment, + isPropertyDeclaration, + isPropertyName, + isPropertyNameLiteral, + isPropertySignature, + isPrototypeAccess, + isPrototypePropertyAssignment, + isPushOrUnshiftIdentifier, + isQualifiedName, + isRequireCall, + isRestParameter, + isRestTypeNode, + isRightSideOfAccessExpression, + isRightSideOfInstanceofExpression, + isRightSideOfQualifiedNameOrPropertyAccess, + isRightSideOfQualifiedNameOrPropertyAccessOrJSDocMemberName, + isSameEntityName, + isSatisfiesExpression, + isSetAccessor, + isSetAccessorDeclaration, + isShorthandAmbientModuleSymbol, + isShorthandPropertyAssignment, + isSingleOrDoubleQuote, + isSourceFile, + isSourceFileJS, + isSpreadAssignment, + isSpreadElement, + isStatement, + isStatementWithLocals, + isStatic, + isString, + isStringANonContextualKeyword, + isStringLiteral, + isStringLiteralLike, + isStringOrNumericLiteralLike, + isSuperCall, + isSuperProperty, + isTaggedTemplateExpression, + isTemplateSpan, + isThisContainerOrFunctionBlock, + isThisIdentifier, + isThisInitializedDeclaration, + isThisInitializedObjectBindingExpression, + isThisInTypeQuery, + isThisProperty, + isThisTypeNode, + isThisTypeParameter, + isThisTypePredicate, + isTransientSymbol, + isTupleTypeNode, + isTypeAlias, + isTypeAliasDeclaration, + isTypeDeclaration, + isTypeLiteralNode, + isTypeNode, + isTypeNodeKind, + isTypeOfExpression, + isTypeOnlyImportDeclaration, + isTypeOnlyImportOrExportDeclaration, + isTypeOperatorNode, + isTypeParameterDeclaration, + isTypePredicateNode, + isTypeQueryNode, + isTypeReferenceNode, + isTypeReferenceType, + isTypeUsableAsPropertyName, + isUMDExportSymbol, + isValidBigIntString, + isValidESSymbolDeclaration, + isValidTypeOnlyAliasUseSite, + isValueSignatureDeclaration, + isVariableDeclaration, + isVariableDeclarationInitializedToBareOrAccessedRequire, + isVariableDeclarationInVariableStatement, + isVariableDeclarationList, + isVariableLike, + isVariableLikeOrAccessor, + isVariableStatement, + isWriteAccess, + isWriteOnlyAccess, + IterableOrIteratorType, + IterationTypes, + JSDoc, + JSDocAugmentsTag, + JSDocCallbackTag, + JSDocComment, + JSDocFunctionType, + JSDocImplementsTag, + JSDocImportTag, + JSDocLink, + JSDocLinkCode, + JSDocLinkPlain, + JSDocMemberName, + JSDocNullableType, + JSDocOptionalType, + JSDocOverloadTag, + JSDocParameterTag, + JSDocPrivateTag, + JSDocPropertyLikeTag, + JSDocPropertyTag, + JSDocProtectedTag, + JSDocPublicTag, + JSDocSatisfiesTag, + JSDocSignature, + JSDocTemplateTag, + JSDocThisTag, + JSDocTypeAssertion, + JSDocTypedefTag, + JSDocTypeExpression, + JSDocTypeLiteral, + JSDocTypeReferencingNode, + JSDocTypeTag, + JSDocVariadicType, + JsxAttribute, + JsxAttributeLike, + JsxAttributeName, + JsxAttributes, + JsxAttributeValue, + JsxChild, + JsxClosingElement, + JsxElement, + JsxEmit, + JsxExpression, + JsxFlags, + JsxFragment, + JsxNamespacedName, + JsxOpeningElement, + JsxOpeningFragment, + JsxOpeningLikeElement, + JsxReferenceKind, + JsxSelfClosingElement, + JsxSpreadAttribute, + JsxTagNameExpression, + KeywordTypeNode, + LabeledStatement, + LanguageFeatureMinimumTarget, + last, + lastOrUndefined, + LateBoundBinaryExpressionDeclaration, + LateBoundDeclaration, + LateBoundName, + LateVisibilityPaintedStatement, + LazyNodeCheckFlags, + length, + LiteralExpression, + LiteralType, + LiteralTypeNode, + map, + mapDefined, + MappedSymbol, + MappedType, + MappedTypeNode, + MatchingKeys, + maybeBind, + MemberOverrideStatus, + MetaProperty, + MethodDeclaration, + MethodSignature, + minAndMax, + MinusToken, + Modifier, + ModifierFlags, + modifiersToFlags, + modifierToFlag, + ModuleBlock, + ModuleDeclaration, + ModuleExportName, + moduleExportNameIsDefault, + moduleExportNameTextEscaped, + moduleExportNameTextUnescaped, + ModuleInstanceState, + ModuleKind, + ModuleResolutionKind, + ModuleSpecifierResolutionHost, + Mutable, + NamedDeclaration, + NamedExports, + NamedImportsOrExports, + NamedTupleMember, + NamespaceDeclaration, + NamespaceExport, + NamespaceExportDeclaration, + NamespaceImport, + needsScopeMarker, + NewExpression, + Node, + NodeArray, + NodeBuilderFlags, + nodeCanBeDecorated, + NodeCheckFlags, + NodeFlags, + nodeHasName, + nodeIsMissing, + nodeIsPresent, + nodeIsSynthesized, + NodeLinks, + nodeStartsNewLexicalEnvironment, + NodeWithTypeArguments, + NonNullChain, + NonNullExpression, + not, + noTruncationMaximumTruncationLength, + NumberLiteralType, + NumericLiteral, + objectAllocator, + ObjectBindingPattern, + ObjectFlags, + ObjectFlagsType, + ObjectLiteralElementLike, + ObjectLiteralExpression, + ObjectType, + OptionalChain, + OptionalTypeNode, + or, + orderedRemoveItemAt, + OuterExpressionKinds, + ParameterDeclaration, + parameterIsThisKeyword, + ParameterPropertyDeclaration, + ParenthesizedExpression, + ParenthesizedTypeNode, + parseIsolatedEntityName, + parseNodeFactory, + parsePseudoBigInt, + parseValidBigInt, + Path, + pathIsRelative, + PatternAmbientModule, + PlusToken, + PostfixUnaryExpression, + PrefixUnaryExpression, + PrivateIdentifier, + Program, + PromiseOrAwaitableType, + PropertyAccessChain, + PropertyAccessEntityNameExpression, + PropertyAccessExpression, + PropertyAssignment, + PropertyDeclaration, + PropertyName, + PropertySignature, + PseudoBigInt, + pseudoBigIntToString, + PunctuationSyntaxKind, + pushIfUnique, + QualifiedName, + QuestionToken, + rangeEquals, + rangeOfNode, + rangeOfTypeParameters, + ReadonlyKeyword, + reduceLeft, + RegularExpressionLiteral, + RelationComparisonResult, + relativeComplement, + removeExtension, + removePrefix, + replaceElement, + resolutionExtensionIsTSOrJson, + ResolutionMode, + ResolvedModuleFull, + ResolvedType, + resolvingEmptyArray, + RestTypeNode, + ReturnStatement, + ReverseMappedSymbol, + ReverseMappedType, + sameMap, + SatisfiesExpression, + Scanner, + scanTokenAtPosition, + ScriptKind, + ScriptTarget, + SetAccessorDeclaration, + setCommentRange as setCommentRangeWorker, + setEmitFlags, + setIdentifierTypeArguments, + setNodeFlags, + setOriginalNode, + setParent, + setSyntheticLeadingComments, + setTextRange as setTextRangeWorker, + setTextRangePosEnd, + setValueDeclaration, + ShorthandPropertyAssignment, + shouldAllowImportingTsExtension, + shouldPreserveConstEnums, + Signature, + SignatureDeclaration, + SignatureFlags, + SignatureKind, + singleElementArray, + SingleSignatureType, + skipOuterExpressions, + skipParentheses, + skipTrivia, + skipTypeChecking, + skipTypeParentheses, + some, + SourceFile, + SpreadAssignment, + SpreadElement, + startsWith, + Statement, + StringLiteral, + StringLiteralLike, + StringLiteralType, + StringMappingType, + stripQuotes, + StructuredType, + SubstitutionType, + SuperCall, + SwitchStatement, + Symbol, + SymbolAccessibility, + SymbolAccessibilityResult, + SymbolFlags, + SymbolFormatFlags, + SymbolId, + SymbolLinks, + symbolName, + SymbolTable, + SymbolTracker, + SymbolVisibilityResult, + SyntaxKind, + SyntheticDefaultModuleType, + SyntheticExpression, + TaggedTemplateExpression, + TemplateExpression, + TemplateLiteralType, + TemplateLiteralTypeNode, + Ternary, + textRangeContainsPositionInclusive, + TextSpan, + textSpanContainsPosition, + textSpanEnd, + ThisExpression, + ThisTypeNode, + ThrowStatement, + TokenFlags, + tokenToString, + tracing, + TracingNode, + TrackedSymbol, + TransientSymbol, + TransientSymbolLinks, + tryAddToSet, + tryCast, + tryExtractTSExtension, + tryGetClassImplementingOrExtendingExpressionWithTypeArguments, + tryGetExtensionFromPath, + tryGetJSDocSatisfiesTypeNode, + tryGetModuleSpecifierFromDeclaration, + tryGetPropertyAccessOrIdentifierToString, + TryStatement, + TupleType, + TupleTypeNode, + TupleTypeReference, + Type, + TypeAliasDeclaration, + TypeAssertion, + TypeChecker, + TypeCheckerHost, + TypeComparer, + TypeElement, + TypeFlags, + TypeFormatFlags, + TypeId, + TypeLiteralNode, + TypeMapKind, + TypeMapper, + TypeNode, + TypeNodeSyntaxKind, + TypeOfExpression, + TypeOnlyAliasDeclaration, + TypeOnlyCompatibleAliasDeclaration, + TypeOperatorNode, + TypeParameter, + TypeParameterDeclaration, + TypePredicate, + TypePredicateKind, + TypePredicateNode, + TypeQueryNode, + TypeReference, + TypeReferenceNode, + TypeReferenceSerializationKind, + TypeReferenceType, + TypeVariable, + unescapeLeadingUnderscores, + UnionOrIntersectionType, + UnionOrIntersectionTypeNode, + UnionReduction, + UnionType, + UnionTypeNode, + UniqueESSymbolType, + usingSingleLineStringWriter, + VariableDeclaration, + VariableDeclarationList, + VariableLikeDeclaration, + VariableStatement, + VarianceFlags, + visitEachChild as visitEachChildWorker, + visitNode, + visitNodes, + Visitor, + VisitResult, + VoidExpression, + walkUpBindingElementsAndPatterns, + walkUpOuterExpressions, + walkUpParenthesizedExpressions, + walkUpParenthesizedTypes, + walkUpParenthesizedTypesAndGetParentAndChild, + WhileStatement, + WideningContext, + WithStatement, + YieldExpression, +} from "./_namespaces/ts.js"; +import * as moduleSpecifiers from "./_namespaces/ts.moduleSpecifiers.js"; +import * as performance from "./_namespaces/ts.performance.js"; + +const ambientModuleSymbolRegex = /^".+"$/; +const anon = "(anonymous)" as __String & string; + +const enum ReferenceHint { + Unspecified, + Identifier, + Property, + ExportAssignment, + Jsx, + AsyncFunction, + ExportImportEquals, + ExportSpecifier, + Decorator, +} + +let nextSymbolId = 1; +let nextNodeId = 1; +let nextMergeId = 1; +let nextFlowId = 1; + +const enum IterationUse { + AllowsSyncIterablesFlag = 1 << 0, + AllowsAsyncIterablesFlag = 1 << 1, + AllowsStringInputFlag = 1 << 2, + ForOfFlag = 1 << 3, + YieldStarFlag = 1 << 4, + SpreadFlag = 1 << 5, + DestructuringFlag = 1 << 6, + PossiblyOutOfBounds = 1 << 7, + + // Spread, Destructuring, Array element assignment + Element = AllowsSyncIterablesFlag, + Spread = AllowsSyncIterablesFlag | SpreadFlag, + Destructuring = AllowsSyncIterablesFlag | DestructuringFlag, + + ForOf = AllowsSyncIterablesFlag | AllowsStringInputFlag | ForOfFlag, + ForAwaitOf = AllowsSyncIterablesFlag | AllowsAsyncIterablesFlag | AllowsStringInputFlag | ForOfFlag, + + YieldStar = AllowsSyncIterablesFlag | YieldStarFlag, + AsyncYieldStar = AllowsSyncIterablesFlag | AllowsAsyncIterablesFlag | YieldStarFlag, + + GeneratorReturnType = AllowsSyncIterablesFlag, + AsyncGeneratorReturnType = AllowsAsyncIterablesFlag, +} + +const enum IterationTypeKind { + Yield, + Return, + Next, +} + +interface IterationTypesResolver { + iterableCacheKey: "iterationTypesOfAsyncIterable" | "iterationTypesOfIterable"; + iteratorCacheKey: "iterationTypesOfAsyncIterator" | "iterationTypesOfIterator"; + iteratorSymbolName: "asyncIterator" | "iterator"; + getGlobalIteratorType: (reportErrors: boolean) => GenericType; + getGlobalIterableType: (reportErrors: boolean) => GenericType; + getGlobalIterableIteratorType: (reportErrors: boolean) => GenericType; + getGlobalGeneratorType: (reportErrors: boolean) => GenericType; + resolveIterationType: (type: Type, errorNode: Node | undefined) => Type | undefined; + mustHaveANextMethodDiagnostic: DiagnosticMessage; + mustBeAMethodDiagnostic: DiagnosticMessage; + mustHaveAValueDiagnostic: DiagnosticMessage; +} + +const enum WideningKind { + Normal, + FunctionReturn, + GeneratorNext, + GeneratorYield, +} + +// dprint-ignore +/** @internal */ +export const enum TypeFacts { + None = 0, + TypeofEQString = 1 << 0, // typeof x === "string" + TypeofEQNumber = 1 << 1, // typeof x === "number" + TypeofEQBigInt = 1 << 2, // typeof x === "bigint" + TypeofEQBoolean = 1 << 3, // typeof x === "boolean" + TypeofEQSymbol = 1 << 4, // typeof x === "symbol" + TypeofEQObject = 1 << 5, // typeof x === "object" + TypeofEQFunction = 1 << 6, // typeof x === "function" + TypeofEQHostObject = 1 << 7, // typeof x === "xxx" + TypeofNEString = 1 << 8, // typeof x !== "string" + TypeofNENumber = 1 << 9, // typeof x !== "number" + TypeofNEBigInt = 1 << 10, // typeof x !== "bigint" + TypeofNEBoolean = 1 << 11, // typeof x !== "boolean" + TypeofNESymbol = 1 << 12, // typeof x !== "symbol" + TypeofNEObject = 1 << 13, // typeof x !== "object" + TypeofNEFunction = 1 << 14, // typeof x !== "function" + TypeofNEHostObject = 1 << 15, // typeof x !== "xxx" + EQUndefined = 1 << 16, // x === undefined + EQNull = 1 << 17, // x === null + EQUndefinedOrNull = 1 << 18, // x === undefined / x === null + NEUndefined = 1 << 19, // x !== undefined + NENull = 1 << 20, // x !== null + NEUndefinedOrNull = 1 << 21, // x != undefined / x != null + Truthy = 1 << 22, // x + Falsy = 1 << 23, // !x + IsUndefined = 1 << 24, // Contains undefined or intersection with undefined + IsNull = 1 << 25, // Contains null or intersection with null + IsUndefinedOrNull = IsUndefined | IsNull, + All = (1 << 27) - 1, + // The following members encode facts about particular kinds of types for use in the getTypeFacts function. + // The presence of a particular fact means that the given test is true for some (and possibly all) values + // of that kind of type. + BaseStringStrictFacts = TypeofEQString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseStringFacts = BaseStringStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + StringStrictFacts = BaseStringStrictFacts | Truthy | Falsy, + StringFacts = BaseStringFacts | Truthy, + EmptyStringStrictFacts = BaseStringStrictFacts | Falsy, + EmptyStringFacts = BaseStringFacts, + NonEmptyStringStrictFacts = BaseStringStrictFacts | Truthy, + NonEmptyStringFacts = BaseStringFacts | Truthy, + BaseNumberStrictFacts = TypeofEQNumber | TypeofNEString | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseNumberFacts = BaseNumberStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + NumberStrictFacts = BaseNumberStrictFacts | Truthy | Falsy, + NumberFacts = BaseNumberFacts | Truthy, + ZeroNumberStrictFacts = BaseNumberStrictFacts | Falsy, + ZeroNumberFacts = BaseNumberFacts, + NonZeroNumberStrictFacts = BaseNumberStrictFacts | Truthy, + NonZeroNumberFacts = BaseNumberFacts | Truthy, + BaseBigIntStrictFacts = TypeofEQBigInt | TypeofNEString | TypeofNENumber | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseBigIntFacts = BaseBigIntStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + BigIntStrictFacts = BaseBigIntStrictFacts | Truthy | Falsy, + BigIntFacts = BaseBigIntFacts | Truthy, + ZeroBigIntStrictFacts = BaseBigIntStrictFacts | Falsy, + ZeroBigIntFacts = BaseBigIntFacts, + NonZeroBigIntStrictFacts = BaseBigIntStrictFacts | Truthy, + NonZeroBigIntFacts = BaseBigIntFacts | Truthy, + BaseBooleanStrictFacts = TypeofEQBoolean | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseBooleanFacts = BaseBooleanStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + BooleanStrictFacts = BaseBooleanStrictFacts | Truthy | Falsy, + BooleanFacts = BaseBooleanFacts | Truthy, + FalseStrictFacts = BaseBooleanStrictFacts | Falsy, + FalseFacts = BaseBooleanFacts, + TrueStrictFacts = BaseBooleanStrictFacts | Truthy, + TrueFacts = BaseBooleanFacts | Truthy, + SymbolStrictFacts = TypeofEQSymbol | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull | Truthy, + SymbolFacts = SymbolStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + ObjectStrictFacts = TypeofEQObject | TypeofEQHostObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEFunction | NEUndefined | NENull | NEUndefinedOrNull | Truthy, + ObjectFacts = ObjectStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + FunctionStrictFacts = TypeofEQFunction | TypeofEQHostObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | NEUndefined | NENull | NEUndefinedOrNull | Truthy, + FunctionFacts = FunctionStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + VoidFacts = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | EQUndefined | EQUndefinedOrNull | NENull | Falsy, + UndefinedFacts = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | EQUndefined | EQUndefinedOrNull | NENull | Falsy | IsUndefined, + NullFacts = TypeofEQObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEFunction | TypeofNEHostObject | EQNull | EQUndefinedOrNull | NEUndefined | Falsy | IsNull, + EmptyObjectStrictFacts = All & ~(EQUndefined | EQNull | EQUndefinedOrNull | IsUndefinedOrNull), + EmptyObjectFacts = All & ~IsUndefinedOrNull, + UnknownFacts = All & ~IsUndefinedOrNull, + AllTypeofNE = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | NEUndefined, + // Masks + OrFactsMask = TypeofEQFunction | TypeofNEObject, + AndFactsMask = All & ~OrFactsMask, +} + +const typeofNEFacts: ReadonlyMap = new Map(Object.entries({ + string: TypeFacts.TypeofNEString, + number: TypeFacts.TypeofNENumber, + bigint: TypeFacts.TypeofNEBigInt, + boolean: TypeFacts.TypeofNEBoolean, + symbol: TypeFacts.TypeofNESymbol, + undefined: TypeFacts.NEUndefined, + object: TypeFacts.TypeofNEObject, + function: TypeFacts.TypeofNEFunction, +})); + +type TypeSystemEntity = Node | Symbol | Type | Signature; + +const enum TypeSystemPropertyName { + Type, + ResolvedBaseConstructorType, + DeclaredType, + ResolvedReturnType, + ImmediateBaseConstraint, + ResolvedTypeArguments, + ResolvedBaseTypes, + WriteType, + ParameterInitializerContainsUndefined, +} + +// dprint-ignore +/** @internal */ +export const enum CheckMode { + Normal = 0, // Normal type checking + Contextual = 1 << 0, // Explicitly assigned contextual type, therefore not cacheable + Inferential = 1 << 1, // Inferential typing + SkipContextSensitive = 1 << 2, // Skip context sensitive function expressions + SkipGenericFunctions = 1 << 3, // Skip single signature generic functions + IsForSignatureHelp = 1 << 4, // Call resolution for purposes of signature help + RestBindingElement = 1 << 5, // Checking a type that is going to be used to determine the type of a rest binding element + // e.g. in `const { a, ...rest } = foo`, when checking the type of `foo` to determine the type of `rest`, + // we need to preserve generic types instead of substituting them for constraints + TypeOnly = 1 << 6, // Called from getTypeOfExpression, diagnostics may be omitted +} + +/** @internal */ +export const enum SignatureCheckMode { + None = 0, + BivariantCallback = 1 << 0, + StrictCallback = 1 << 1, + IgnoreReturnTypes = 1 << 2, + StrictArity = 1 << 3, + StrictTopSignature = 1 << 4, + Callback = BivariantCallback | StrictCallback, +} + +const enum IntersectionState { + None = 0, + Source = 1 << 0, // Source type is a constituent of an outer intersection + Target = 1 << 1, // Target type is a constituent of an outer intersection +} + +const enum RecursionFlags { + None = 0, + Source = 1 << 0, + Target = 1 << 1, + Both = Source | Target, +} + +const enum MappedTypeModifiers { + IncludeReadonly = 1 << 0, + ExcludeReadonly = 1 << 1, + IncludeOptional = 1 << 2, + ExcludeOptional = 1 << 3, +} + +const enum MappedTypeNameTypeKind { + None, + Filtering, + Remapping, +} + +const enum ExpandingFlags { + None = 0, + Source = 1, + Target = 1 << 1, + Both = Source | Target, +} + +const enum MembersOrExportsResolutionKind { + resolvedExports = "resolvedExports", + resolvedMembers = "resolvedMembers", +} + +const enum UnusedKind { + Local, + Parameter, +} + +/** @param containingNode Node to check for parse error */ +type AddUnusedDiagnostic = (containingNode: Node, type: UnusedKind, diagnostic: DiagnosticWithLocation) => void; + +const isNotOverloadAndNotAccessor = and(isNotOverload, isNotAccessor); + +const enum DeclarationMeaning { + GetAccessor = 1, + SetAccessor = 2, + PropertyAssignment = 4, + Method = 8, + PrivateStatic = 16, + GetOrSetAccessor = GetAccessor | SetAccessor, + PropertyAssignmentOrMethod = PropertyAssignment | Method, +} + +const enum DeclarationSpaces { + None = 0, + ExportValue = 1 << 0, + ExportType = 1 << 1, + ExportNamespace = 1 << 2, +} + +const enum MinArgumentCountFlags { + None = 0, + StrongArityForUntypedJS = 1 << 0, + VoidIsNonOptional = 1 << 1, +} + +const enum IntrinsicTypeKind { + Uppercase, + Lowercase, + Capitalize, + Uncapitalize, + NoInfer, +} + +const intrinsicTypeKinds: ReadonlyMap = new Map(Object.entries({ + Uppercase: IntrinsicTypeKind.Uppercase, + Lowercase: IntrinsicTypeKind.Lowercase, + Capitalize: IntrinsicTypeKind.Capitalize, + Uncapitalize: IntrinsicTypeKind.Uncapitalize, + NoInfer: IntrinsicTypeKind.NoInfer, +})); + +const SymbolLinks = class implements SymbolLinks { + declare _symbolLinksBrand: any; +}; + +function NodeLinks(this: NodeLinks) { + this.flags = NodeCheckFlags.None; +} + +/** @internal */ +export function getNodeId(node: Node): number { + if (!node.id) { + node.id = nextNodeId; + nextNodeId++; + } + return node.id; +} + +/** @internal */ +export function getSymbolId(symbol: Symbol): SymbolId { + if (!symbol.id) { + symbol.id = nextSymbolId; + nextSymbolId++; + } + + return symbol.id; +} + +/** @internal */ +export function isInstantiatedModule(node: ModuleDeclaration, preserveConstEnums: boolean) { + const moduleState = getModuleInstanceState(node); + return moduleState === ModuleInstanceState.Instantiated || + (preserveConstEnums && moduleState === ModuleInstanceState.ConstEnumOnly); +} + +/** @internal */ +export function createTypeChecker(host: TypeCheckerHost): TypeChecker { + // Why var? It avoids TDZ checks in the runtime which can be costly. + // See: https://github.com/microsoft/TypeScript/issues/52924 + /* eslint-disable no-var */ + var deferredDiagnosticsCallbacks: (() => void)[] = []; + + var addLazyDiagnostic = (arg: () => void) => { + deferredDiagnosticsCallbacks.push(arg); + }; + + // Cancellation that controls whether or not we can cancel in the middle of type checking. + // In general cancelling is *not* safe for the type checker. We might be in the middle of + // computing something, and we will leave our internals in an inconsistent state. Callers + // who set the cancellation token should catch if a cancellation exception occurs, and + // should throw away and create a new TypeChecker. + // + // Currently we only support setting the cancellation token when getting diagnostics. This + // is because diagnostics can be quite expensive, and we want to allow hosts to bail out if + // they no longer need the information (for example, if the user started editing again). + var cancellationToken: CancellationToken | undefined; + + var scanner: Scanner | undefined; + + var Symbol = objectAllocator.getSymbolConstructor(); + var Type = objectAllocator.getTypeConstructor(); + var Signature = objectAllocator.getSignatureConstructor(); + + var typeCount = 0; + var symbolCount = 0; + var totalInstantiationCount = 0; + var instantiationCount = 0; + var instantiationDepth = 0; + var inlineLevel = 0; + var currentNode: Node | undefined; + var varianceTypeParameter: TypeParameter | undefined; + var isInferencePartiallyBlocked = false; + + var emptySymbols = createSymbolTable(); + var arrayVariances = [VarianceFlags.Covariant]; + + var compilerOptions = host.getCompilerOptions(); + var languageVersion = getEmitScriptTarget(compilerOptions); + var moduleKind = getEmitModuleKind(compilerOptions); + var legacyDecorators = !!compilerOptions.experimentalDecorators; + var useDefineForClassFields = getUseDefineForClassFields(compilerOptions); + var emitStandardClassFields = getEmitStandardClassFields(compilerOptions); + var allowSyntheticDefaultImports = getAllowSyntheticDefaultImports(compilerOptions); + var strictNullChecks = getStrictOptionValue(compilerOptions, "strictNullChecks"); + var strictFunctionTypes = getStrictOptionValue(compilerOptions, "strictFunctionTypes"); + var strictBindCallApply = getStrictOptionValue(compilerOptions, "strictBindCallApply"); + var strictPropertyInitialization = getStrictOptionValue(compilerOptions, "strictPropertyInitialization"); + var noImplicitAny = getStrictOptionValue(compilerOptions, "noImplicitAny"); + var noImplicitThis = getStrictOptionValue(compilerOptions, "noImplicitThis"); + var useUnknownInCatchVariables = getStrictOptionValue(compilerOptions, "useUnknownInCatchVariables"); + var exactOptionalPropertyTypes = compilerOptions.exactOptionalPropertyTypes; + + var checkBinaryExpression = createCheckBinaryExpression(); + var emitResolver = createResolver(); + var nodeBuilder = createNodeBuilder(); + var syntacticNodeBuilder = createSyntacticTypeNodeBuilder(compilerOptions, { + isEntityNameVisible, + isExpandoFunctionDeclaration, + getAllAccessorDeclarations: getAllAccessorDeclarationsForDeclaration, + requiresAddingImplicitUndefined, + isUndefinedIdentifierExpression(node: Identifier) { + Debug.assert(isExpressionNode(node)); + return getSymbolAtLocation(node) === undefinedSymbol; + }, + isDefinitelyReferenceToGlobalSymbolObject, + }); + var evaluate = createEvaluator({ + evaluateElementAccessExpression, + evaluateEntityNameExpression, + }); + + var globals = createSymbolTable(); + var undefinedSymbol = createSymbol(SymbolFlags.Property, "undefined" as __String); + undefinedSymbol.declarations = []; + + var globalThisSymbol = createSymbol(SymbolFlags.Module, "globalThis" as __String, CheckFlags.Readonly); + globalThisSymbol.exports = globals; + globalThisSymbol.declarations = []; + globals.set(globalThisSymbol.escapedName, globalThisSymbol); + + var argumentsSymbol = createSymbol(SymbolFlags.Property, "arguments" as __String); + var requireSymbol = createSymbol(SymbolFlags.Property, "require" as __String); + var isolatedModulesLikeFlagName = compilerOptions.verbatimModuleSyntax ? "verbatimModuleSyntax" : "isolatedModules"; + var canCollectSymbolAliasAccessabilityData = !compilerOptions.verbatimModuleSyntax; + + /** This will be set during calls to `getResolvedSignature` where services determines an apparent number of arguments greater than what is actually provided. */ + var apparentArgumentCount: number | undefined; + + var lastGetCombinedNodeFlagsNode: Node | undefined; + var lastGetCombinedNodeFlagsResult = NodeFlags.None; + var lastGetCombinedModifierFlagsNode: Declaration | undefined; + var lastGetCombinedModifierFlagsResult = ModifierFlags.None; + var resolveName = createNameResolver({ + compilerOptions, + requireSymbol, + argumentsSymbol, + globals, + getSymbolOfDeclaration, + error, + getRequiresScopeChangeCache, + setRequiresScopeChangeCache, + lookup: getSymbol, + onPropertyWithInvalidInitializer: checkAndReportErrorForInvalidInitializer, + onFailedToResolveSymbol, + onSuccessfullyResolvedSymbol, + }); + + var resolveNameForSymbolSuggestion = createNameResolver({ + compilerOptions, + requireSymbol, + argumentsSymbol, + globals, + getSymbolOfDeclaration, + error, + getRequiresScopeChangeCache, + setRequiresScopeChangeCache, + lookup: getSuggestionForSymbolNameLookup, + }); + // for public members that accept a Node or one of its subtypes, we must guard against + // synthetic nodes created during transformations by calling `getParseTreeNode`. + // for most of these, we perform the guard only on `checker` to avoid any possible + // extra cost of calling `getParseTreeNode` when calling these functions from inside the + // checker. + const checker: TypeChecker = { + getNodeCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.nodeCount, 0), + getIdentifierCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.identifierCount, 0), + getSymbolCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.symbolCount, symbolCount), + getTypeCount: () => typeCount, + getInstantiationCount: () => totalInstantiationCount, + getRelationCacheSizes: () => ({ + assignable: assignableRelation.size, + identity: identityRelation.size, + subtype: subtypeRelation.size, + strictSubtype: strictSubtypeRelation.size, + }), + isUndefinedSymbol: symbol => symbol === undefinedSymbol, + isArgumentsSymbol: symbol => symbol === argumentsSymbol, + isUnknownSymbol: symbol => symbol === unknownSymbol, + getMergedSymbol, + symbolIsValue, + getDiagnostics, + getGlobalDiagnostics, + getRecursionIdentity, + getUnmatchedProperties, + getTypeOfSymbolAtLocation: (symbol, locationIn) => { + const location = getParseTreeNode(locationIn); + return location ? getTypeOfSymbolAtLocation(symbol, location) : errorType; + }, + getTypeOfSymbol, + getSymbolsOfParameterPropertyDeclaration: (parameterIn, parameterName) => { + const parameter = getParseTreeNode(parameterIn, isParameter); + if (parameter === undefined) return Debug.fail("Cannot get symbols of a synthetic parameter that cannot be resolved to a parse-tree node."); + Debug.assert(isParameterPropertyDeclaration(parameter, parameter.parent)); + return getSymbolsOfParameterPropertyDeclaration(parameter, escapeLeadingUnderscores(parameterName)); + }, + getDeclaredTypeOfSymbol, + getPropertiesOfType, + getPropertyOfType: (type, name) => getPropertyOfType(type, escapeLeadingUnderscores(name)), + getPrivateIdentifierPropertyOfType: (leftType: Type, name: string, location: Node) => { + const node = getParseTreeNode(location); + if (!node) { + return undefined; + } + const propName = escapeLeadingUnderscores(name); + const lexicallyScopedIdentifier = lookupSymbolForPrivateIdentifierDeclaration(propName, node); + return lexicallyScopedIdentifier ? getPrivateIdentifierPropertyOfType(leftType, lexicallyScopedIdentifier) : undefined; + }, + getTypeOfPropertyOfType: (type, name) => getTypeOfPropertyOfType(type, escapeLeadingUnderscores(name)), + getIndexInfoOfType: (type, kind) => getIndexInfoOfType(type, kind === IndexKind.String ? stringType : numberType), + getIndexInfosOfType, + getIndexInfosOfIndexSymbol, + getSignaturesOfType, + getIndexTypeOfType: (type, kind) => getIndexTypeOfType(type, kind === IndexKind.String ? stringType : numberType), + getIndexType: type => getIndexType(type), + getBaseTypes, + getBaseTypeOfLiteralType, + getWidenedType, + getWidenedLiteralType, + getTypeFromTypeNode: nodeIn => { + const node = getParseTreeNode(nodeIn, isTypeNode); + return node ? getTypeFromTypeNode(node) : errorType; + }, + getParameterType: getTypeAtPosition, + getParameterIdentifierInfoAtPosition, + getPromisedTypeOfPromise, + getAwaitedType: type => getAwaitedType(type), + getReturnTypeOfSignature, + isNullableType, + getNullableType, + getNonNullableType, + getNonOptionalType: removeOptionalTypeMarker, + getTypeArguments, + typeToTypeNode: nodeBuilder.typeToTypeNode, + indexInfoToIndexSignatureDeclaration: nodeBuilder.indexInfoToIndexSignatureDeclaration, + signatureToSignatureDeclaration: nodeBuilder.signatureToSignatureDeclaration, + symbolToEntityName: nodeBuilder.symbolToEntityName, + symbolToExpression: nodeBuilder.symbolToExpression, + symbolToNode: nodeBuilder.symbolToNode, + symbolToTypeParameterDeclarations: nodeBuilder.symbolToTypeParameterDeclarations, + symbolToParameterDeclaration: nodeBuilder.symbolToParameterDeclaration, + typeParameterToDeclaration: nodeBuilder.typeParameterToDeclaration, + getSymbolsInScope: (locationIn, meaning) => { + const location = getParseTreeNode(locationIn); + return location ? getSymbolsInScope(location, meaning) : []; + }, + getSymbolAtLocation: nodeIn => { + const node = getParseTreeNode(nodeIn); + // set ignoreErrors: true because any lookups invoked by the API shouldn't cause any new errors + return node ? getSymbolAtLocation(node, /*ignoreErrors*/ true) : undefined; + }, + getIndexInfosAtLocation: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node ? getIndexInfosAtLocation(node) : undefined; + }, + getShorthandAssignmentValueSymbol: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node ? getShorthandAssignmentValueSymbol(node) : undefined; + }, + getExportSpecifierLocalTargetSymbol: nodeIn => { + const node = getParseTreeNode(nodeIn, isExportSpecifier); + return node ? getExportSpecifierLocalTargetSymbol(node) : undefined; + }, + getExportSymbolOfSymbol(symbol) { + return getMergedSymbol(symbol.exportSymbol || symbol); + }, + getTypeAtLocation: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node ? getTypeOfNode(node) : errorType; + }, + getTypeOfAssignmentPattern: nodeIn => { + const node = getParseTreeNode(nodeIn, isAssignmentPattern); + return node && getTypeOfAssignmentPattern(node) || errorType; + }, + getPropertySymbolOfDestructuringAssignment: locationIn => { + const location = getParseTreeNode(locationIn, isIdentifier); + return location ? getPropertySymbolOfDestructuringAssignment(location) : undefined; + }, + signatureToString: (signature, enclosingDeclaration, flags, kind) => { + return signatureToString(signature, getParseTreeNode(enclosingDeclaration), flags, kind); + }, + typeToString: (type, enclosingDeclaration, flags) => { + return typeToString(type, getParseTreeNode(enclosingDeclaration), flags); + }, + symbolToString: (symbol, enclosingDeclaration, meaning, flags) => { + return symbolToString(symbol, getParseTreeNode(enclosingDeclaration), meaning, flags); + }, + typePredicateToString: (predicate, enclosingDeclaration, flags) => { + return typePredicateToString(predicate, getParseTreeNode(enclosingDeclaration), flags); + }, + writeSignature: (signature, enclosingDeclaration, flags, kind, writer) => { + return signatureToString(signature, getParseTreeNode(enclosingDeclaration), flags, kind, writer); + }, + writeType: (type, enclosingDeclaration, flags, writer) => { + return typeToString(type, getParseTreeNode(enclosingDeclaration), flags, writer); + }, + writeSymbol: (symbol, enclosingDeclaration, meaning, flags, writer) => { + return symbolToString(symbol, getParseTreeNode(enclosingDeclaration), meaning, flags, writer); + }, + writeTypePredicate: (predicate, enclosingDeclaration, flags, writer) => { + return typePredicateToString(predicate, getParseTreeNode(enclosingDeclaration), flags, writer); + }, + getAugmentedPropertiesOfType, + getRootSymbols, + getSymbolOfExpando, + getContextualType: (nodeIn: Expression, contextFlags?: ContextFlags) => { + const node = getParseTreeNode(nodeIn, isExpression); + if (!node) { + return undefined; + } + if (contextFlags! & ContextFlags.Completions) { + return runWithInferenceBlockedFromSourceNode(node, () => getContextualType(node, contextFlags)); + } + return getContextualType(node, contextFlags); + }, + getContextualTypeForObjectLiteralElement: nodeIn => { + const node = getParseTreeNode(nodeIn, isObjectLiteralElementLike); + return node ? getContextualTypeForObjectLiteralElement(node, /*contextFlags*/ undefined) : undefined; + }, + getContextualTypeForArgumentAtIndex: (nodeIn, argIndex) => { + const node = getParseTreeNode(nodeIn, isCallLikeExpression); + return node && getContextualTypeForArgumentAtIndex(node, argIndex); + }, + getContextualTypeForJsxAttribute: nodeIn => { + const node = getParseTreeNode(nodeIn, isJsxAttributeLike); + return node && getContextualTypeForJsxAttribute(node, /*contextFlags*/ undefined); + }, + isContextSensitive, + getTypeOfPropertyOfContextualType, + getFullyQualifiedName, + getResolvedSignature: (node, candidatesOutArray, argumentCount) => getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.Normal), + getCandidateSignaturesForStringLiteralCompletions, + getResolvedSignatureForSignatureHelp: (node, candidatesOutArray, argumentCount) => runWithoutResolvedSignatureCaching(node, () => getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.IsForSignatureHelp)), + getExpandedParameters, + hasEffectiveRestParameter, + containsArgumentsReference, + getConstantValue: nodeIn => { + const node = getParseTreeNode(nodeIn, canHaveConstantValue); + return node ? getConstantValue(node) : undefined; + }, + isValidPropertyAccess: (nodeIn, propertyName) => { + const node = getParseTreeNode(nodeIn, isPropertyAccessOrQualifiedNameOrImportTypeNode); + return !!node && isValidPropertyAccess(node, escapeLeadingUnderscores(propertyName)); + }, + isValidPropertyAccessForCompletions: (nodeIn, type, property) => { + const node = getParseTreeNode(nodeIn, isPropertyAccessExpression); + return !!node && isValidPropertyAccessForCompletions(node, type, property); + }, + getSignatureFromDeclaration: declarationIn => { + const declaration = getParseTreeNode(declarationIn, isFunctionLike); + return declaration ? getSignatureFromDeclaration(declaration) : undefined; + }, + isImplementationOfOverload: nodeIn => { + const node = getParseTreeNode(nodeIn, isFunctionLike); + return node ? isImplementationOfOverload(node) : undefined; + }, + getImmediateAliasedSymbol, + getAliasedSymbol: resolveAlias, + getEmitResolver, + requiresAddingImplicitUndefined, + getExportsOfModule: getExportsOfModuleAsArray, + getExportsAndPropertiesOfModule, + forEachExportAndPropertyOfModule, + getSymbolWalker: createGetSymbolWalker( + getRestTypeOfSignature, + getTypePredicateOfSignature, + getReturnTypeOfSignature, + getBaseTypes, + resolveStructuredTypeMembers, + getTypeOfSymbol, + getResolvedSymbol, + getConstraintOfTypeParameter, + getFirstIdentifier, + getTypeArguments, + ), + getAmbientModules, + getJsxIntrinsicTagNamesAt, + isOptionalParameter: nodeIn => { + const node = getParseTreeNode(nodeIn, isParameter); + return node ? isOptionalParameter(node) : false; + }, + tryGetMemberInModuleExports: (name, symbol) => tryGetMemberInModuleExports(escapeLeadingUnderscores(name), symbol), + tryGetMemberInModuleExportsAndProperties: (name, symbol) => tryGetMemberInModuleExportsAndProperties(escapeLeadingUnderscores(name), symbol), + tryFindAmbientModule: moduleName => tryFindAmbientModule(moduleName, /*withAugmentations*/ true), + tryFindAmbientModuleWithoutAugmentations: moduleName => { + // we deliberately exclude augmentations + // since we are only interested in declarations of the module itself + return tryFindAmbientModule(moduleName, /*withAugmentations*/ false); + }, + getApparentType, + getUnionType, + isTypeAssignableTo, + createAnonymousType, + createSignature, + createSymbol, + createIndexInfo, + getAnyType: () => anyType, + getStringType: () => stringType, + getStringLiteralType, + getNumberType: () => numberType, + getNumberLiteralType, + getBigIntType: () => bigintType, + getBigIntLiteralType, + createPromiseType, + createArrayType, + getElementTypeOfArrayType, + getBooleanType: () => booleanType, + getFalseType: (fresh?) => fresh ? falseType : regularFalseType, + getTrueType: (fresh?) => fresh ? trueType : regularTrueType, + getVoidType: () => voidType, + getUndefinedType: () => undefinedType, + getNullType: () => nullType, + getESSymbolType: () => esSymbolType, + getNeverType: () => neverType, + getOptionalType: () => optionalType, + getPromiseType: () => getGlobalPromiseType(/*reportErrors*/ false), + getPromiseLikeType: () => getGlobalPromiseLikeType(/*reportErrors*/ false), + getAsyncIterableType: () => { + const type = getGlobalAsyncIterableType(/*reportErrors*/ false); + if (type === emptyGenericType) return undefined; + return type; + }, + isSymbolAccessible, + isArrayType, + isTupleType, + isArrayLikeType, + isEmptyAnonymousObjectType, + isTypeInvalidDueToUnionDiscriminant, + getExactOptionalProperties, + getAllPossiblePropertiesOfTypes, + getSuggestedSymbolForNonexistentProperty, + getSuggestedSymbolForNonexistentJSXAttribute, + getSuggestedSymbolForNonexistentSymbol: (location, name, meaning) => getSuggestedSymbolForNonexistentSymbol(location, escapeLeadingUnderscores(name), meaning), + getSuggestedSymbolForNonexistentModule, + getSuggestedSymbolForNonexistentClassMember, + getBaseConstraintOfType, + getDefaultFromTypeParameter: type => type && type.flags & TypeFlags.TypeParameter ? getDefaultFromTypeParameter(type as TypeParameter) : undefined, + resolveName(name, location, meaning, excludeGlobals) { + return resolveName(location, escapeLeadingUnderscores(name), meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false, excludeGlobals); + }, + getJsxNamespace: n => unescapeLeadingUnderscores(getJsxNamespace(n)), + getJsxFragmentFactory: n => { + const jsxFragmentFactory = getJsxFragmentFactoryEntity(n); + return jsxFragmentFactory && unescapeLeadingUnderscores(getFirstIdentifier(jsxFragmentFactory).escapedText); + }, + getAccessibleSymbolChain, + getTypePredicateOfSignature, + resolveExternalModuleName: moduleSpecifierIn => { + const moduleSpecifier = getParseTreeNode(moduleSpecifierIn, isExpression); + return moduleSpecifier && resolveExternalModuleName(moduleSpecifier, moduleSpecifier, /*ignoreErrors*/ true); + }, + resolveExternalModuleSymbol, + tryGetThisTypeAt: (nodeIn, includeGlobalThis, container) => { + const node = getParseTreeNode(nodeIn); + return node && tryGetThisTypeAt(node, includeGlobalThis, container); + }, + getTypeArgumentConstraint: nodeIn => { + const node = getParseTreeNode(nodeIn, isTypeNode); + return node && getTypeArgumentConstraint(node); + }, + getSuggestionDiagnostics: (fileIn, ct) => { + const file = getParseTreeNode(fileIn, isSourceFile) || Debug.fail("Could not determine parsed source file."); + if (skipTypeChecking(file, compilerOptions, host)) { + return emptyArray; + } + + let diagnostics: DiagnosticWithLocation[] | undefined; + try { + // Record the cancellation token so it can be checked later on during checkSourceElement. + // Do this in a finally block so we can ensure that it gets reset back to nothing after + // this call is done. + cancellationToken = ct; + + // Ensure file is type checked, with _eager_ diagnostic production, so identifiers are registered as potentially unused + checkSourceFileWithEagerDiagnostics(file); + Debug.assert(!!(getNodeLinks(file).flags & NodeCheckFlags.TypeChecked)); + + diagnostics = addRange(diagnostics, suggestionDiagnostics.getDiagnostics(file.fileName)); + checkUnusedIdentifiers(getPotentiallyUnusedIdentifiers(file), (containingNode, kind, diag) => { + if (!containsParseError(containingNode) && !unusedIsError(kind, !!(containingNode.flags & NodeFlags.Ambient))) { + (diagnostics || (diagnostics = [])).push({ ...diag, category: DiagnosticCategory.Suggestion }); + } + }); + + return diagnostics || emptyArray; + } + finally { + cancellationToken = undefined; + } + }, + + runWithCancellationToken: (token, callback) => { + try { + cancellationToken = token; + return callback(checker); + } + finally { + cancellationToken = undefined; + } + }, + + getLocalTypeParametersOfClassOrInterfaceOrTypeAlias, + isDeclarationVisible, + isPropertyAccessible, + getTypeOnlyAliasDeclaration, + getMemberOverrideModifierStatus, + isTypeParameterPossiblyReferenced, + typeHasCallOrConstructSignatures, + getSymbolFlags, + }; + + function getCandidateSignaturesForStringLiteralCompletions(call: CallLikeExpression, editingArgument: Node) { + const candidatesSet = new Set(); + const candidates: Signature[] = []; + + // first, get candidates when inference is blocked from the source node. + runWithInferenceBlockedFromSourceNode(editingArgument, () => getResolvedSignatureWorker(call, candidates, /*argumentCount*/ undefined, CheckMode.Normal)); + for (const candidate of candidates) { + candidatesSet.add(candidate); + } + + // reset candidates for second pass + candidates.length = 0; + + // next, get candidates where the source node is considered for inference. + runWithoutResolvedSignatureCaching(editingArgument, () => getResolvedSignatureWorker(call, candidates, /*argumentCount*/ undefined, CheckMode.Normal)); + for (const candidate of candidates) { + candidatesSet.add(candidate); + } + + return arrayFrom(candidatesSet); + } + + function runWithoutResolvedSignatureCaching(node: Node | undefined, fn: () => T): T { + node = findAncestor(node, isCallLikeOrFunctionLikeExpression); + if (node) { + const cachedResolvedSignatures = []; + const cachedTypes = []; + while (node) { + const nodeLinks = getNodeLinks(node); + cachedResolvedSignatures.push([nodeLinks, nodeLinks.resolvedSignature] as const); + nodeLinks.resolvedSignature = undefined; + if (isFunctionExpressionOrArrowFunction(node)) { + const symbolLinks = getSymbolLinks(getSymbolOfDeclaration(node)); + const type = symbolLinks.type; + cachedTypes.push([symbolLinks, type] as const); + symbolLinks.type = undefined; + } + node = findAncestor(node.parent, isCallLikeOrFunctionLikeExpression); + } + const result = fn(); + for (const [nodeLinks, resolvedSignature] of cachedResolvedSignatures) { + nodeLinks.resolvedSignature = resolvedSignature; + } + for (const [symbolLinks, type] of cachedTypes) { + symbolLinks.type = type; + } + return result; + } + return fn(); + } + + function runWithInferenceBlockedFromSourceNode(node: Node | undefined, fn: () => T): T { + const containingCall = findAncestor(node, isCallLikeExpression); + if (containingCall) { + let toMarkSkip = node!; + do { + getNodeLinks(toMarkSkip).skipDirectInference = true; + toMarkSkip = toMarkSkip.parent; + } + while (toMarkSkip && toMarkSkip !== containingCall); + } + + isInferencePartiallyBlocked = true; + const result = runWithoutResolvedSignatureCaching(node, fn); + isInferencePartiallyBlocked = false; + + if (containingCall) { + let toMarkSkip = node!; + do { + getNodeLinks(toMarkSkip).skipDirectInference = undefined; + toMarkSkip = toMarkSkip.parent; + } + while (toMarkSkip && toMarkSkip !== containingCall); + } + return result; + } + + function getResolvedSignatureWorker(nodeIn: CallLikeExpression, candidatesOutArray: Signature[] | undefined, argumentCount: number | undefined, checkMode: CheckMode): Signature | undefined { + const node = getParseTreeNode(nodeIn, isCallLikeExpression); + apparentArgumentCount = argumentCount; + const res = !node ? undefined : getResolvedSignature(node, candidatesOutArray, checkMode); + apparentArgumentCount = undefined; + return res; + } + + var tupleTypes = new Map(); + var unionTypes = new Map(); + var unionOfUnionTypes = new Map(); + var intersectionTypes = new Map(); + var stringLiteralTypes = new Map(); + var numberLiteralTypes = new Map(); + var bigIntLiteralTypes = new Map(); + var enumLiteralTypes = new Map(); + var indexedAccessTypes = new Map(); + var templateLiteralTypes = new Map(); + var stringMappingTypes = new Map(); + var substitutionTypes = new Map(); + var subtypeReductionCache = new Map(); + var decoratorContextOverrideTypeCache = new Map(); + var cachedTypes = new Map(); + var evolvingArrayTypes: EvolvingArrayType[] = []; + var undefinedProperties: SymbolTable = new Map(); + var markerTypes = new Set(); + + var unknownSymbol = createSymbol(SymbolFlags.Property, "unknown" as __String); + var resolvingSymbol = createSymbol(0, InternalSymbolName.Resolving); + var unresolvedSymbols = new Map(); + var errorTypes = new Map(); + + // We specifically create the `undefined` and `null` types before any other types that can occur in + // unions such that they are given low type IDs and occur first in the sorted list of union constituents. + // We can then just examine the first constituent(s) of a union to check for their presence. + + var seenIntrinsicNames = new Set(); + + var anyType = createIntrinsicType(TypeFlags.Any, "any"); + var autoType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.NonInferrableType, "auto"); + var wildcardType = createIntrinsicType(TypeFlags.Any, "any", /*objectFlags*/ undefined, "wildcard"); + var blockedStringType = createIntrinsicType(TypeFlags.Any, "any", /*objectFlags*/ undefined, "blocked string"); + var errorType = createIntrinsicType(TypeFlags.Any, "error"); + var unresolvedType = createIntrinsicType(TypeFlags.Any, "unresolved"); + var nonInferrableAnyType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.ContainsWideningType, "non-inferrable"); + var intrinsicMarkerType = createIntrinsicType(TypeFlags.Any, "intrinsic"); + var unknownType = createIntrinsicType(TypeFlags.Unknown, "unknown"); + var undefinedType = createIntrinsicType(TypeFlags.Undefined, "undefined"); + var undefinedWideningType = strictNullChecks ? undefinedType : createIntrinsicType(TypeFlags.Undefined, "undefined", ObjectFlags.ContainsWideningType, "widening"); + var missingType = createIntrinsicType(TypeFlags.Undefined, "undefined", /*objectFlags*/ undefined, "missing"); + var undefinedOrMissingType = exactOptionalPropertyTypes ? missingType : undefinedType; + var optionalType = createIntrinsicType(TypeFlags.Undefined, "undefined", /*objectFlags*/ undefined, "optional"); + var nullType = createIntrinsicType(TypeFlags.Null, "null"); + var nullWideningType = strictNullChecks ? nullType : createIntrinsicType(TypeFlags.Null, "null", ObjectFlags.ContainsWideningType, "widening"); + var stringType = createIntrinsicType(TypeFlags.String, "string"); + var numberType = createIntrinsicType(TypeFlags.Number, "number"); + var bigintType = createIntrinsicType(TypeFlags.BigInt, "bigint"); + var falseType = createIntrinsicType(TypeFlags.BooleanLiteral, "false", /*objectFlags*/ undefined, "fresh") as FreshableIntrinsicType; + var regularFalseType = createIntrinsicType(TypeFlags.BooleanLiteral, "false") as FreshableIntrinsicType; + var trueType = createIntrinsicType(TypeFlags.BooleanLiteral, "true", /*objectFlags*/ undefined, "fresh") as FreshableIntrinsicType; + var regularTrueType = createIntrinsicType(TypeFlags.BooleanLiteral, "true") as FreshableIntrinsicType; + trueType.regularType = regularTrueType; + trueType.freshType = trueType; + regularTrueType.regularType = regularTrueType; + regularTrueType.freshType = trueType; + falseType.regularType = regularFalseType; + falseType.freshType = falseType; + regularFalseType.regularType = regularFalseType; + regularFalseType.freshType = falseType; + var booleanType = getUnionType([regularFalseType, regularTrueType]); + var esSymbolType = createIntrinsicType(TypeFlags.ESSymbol, "symbol"); + var voidType = createIntrinsicType(TypeFlags.Void, "void"); + var neverType = createIntrinsicType(TypeFlags.Never, "never"); + var silentNeverType = createIntrinsicType(TypeFlags.Never, "never", ObjectFlags.NonInferrableType, "silent"); + var implicitNeverType = createIntrinsicType(TypeFlags.Never, "never", /*objectFlags*/ undefined, "implicit"); + var unreachableNeverType = createIntrinsicType(TypeFlags.Never, "never", /*objectFlags*/ undefined, "unreachable"); + var nonPrimitiveType = createIntrinsicType(TypeFlags.NonPrimitive, "object"); + var stringOrNumberType = getUnionType([stringType, numberType]); + var stringNumberSymbolType = getUnionType([stringType, numberType, esSymbolType]); + var numberOrBigIntType = getUnionType([numberType, bigintType]); + var templateConstraintType = getUnionType([stringType, numberType, booleanType, bigintType, nullType, undefinedType]) as UnionType; + var numericStringType = getTemplateLiteralType(["", ""], [numberType]); // The `${number}` type + + var restrictiveMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? getRestrictiveTypeParameter(t as TypeParameter) : t, () => "(restrictive mapper)"); + var permissiveMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? wildcardType : t, () => "(permissive mapper)"); + var uniqueLiteralType = createIntrinsicType(TypeFlags.Never, "never", /*objectFlags*/ undefined, "unique literal"); // `uniqueLiteralType` is a special `never` flagged by union reduction to behave as a literal + var uniqueLiteralMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? uniqueLiteralType : t, () => "(unique literal mapper)"); // replace all type parameters with the unique literal type (disregarding constraints) + var outofbandVarianceMarkerHandler: ((onlyUnreliable: boolean) => void) | undefined; + var reportUnreliableMapper = makeFunctionTypeMapper(t => { + if (outofbandVarianceMarkerHandler && (t === markerSuperType || t === markerSubType || t === markerOtherType)) { + outofbandVarianceMarkerHandler(/*onlyUnreliable*/ true); + } + return t; + }, () => "(unmeasurable reporter)"); + var reportUnmeasurableMapper = makeFunctionTypeMapper(t => { + if (outofbandVarianceMarkerHandler && (t === markerSuperType || t === markerSubType || t === markerOtherType)) { + outofbandVarianceMarkerHandler(/*onlyUnreliable*/ false); + } + return t; + }, () => "(unreliable reporter)"); + + var emptyObjectType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var emptyJsxObjectType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + emptyJsxObjectType.objectFlags |= ObjectFlags.JsxAttributes; + + var emptyTypeLiteralSymbol = createSymbol(SymbolFlags.TypeLiteral, InternalSymbolName.Type); + emptyTypeLiteralSymbol.members = createSymbolTable(); + var emptyTypeLiteralType = createAnonymousType(emptyTypeLiteralSymbol, emptySymbols, emptyArray, emptyArray, emptyArray); + + var unknownEmptyObjectType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var unknownUnionType = strictNullChecks ? getUnionType([undefinedType, nullType, unknownEmptyObjectType]) : unknownType; + + var emptyGenericType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray) as ObjectType as GenericType; + emptyGenericType.instantiations = new Map(); + + var anyFunctionType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + // The anyFunctionType contains the anyFunctionType by definition. The flag is further propagated + // in getPropagatingFlagsOfTypes, and it is checked in inferFromTypes. + anyFunctionType.objectFlags |= ObjectFlags.NonInferrableType; + + var noConstraintType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var circularConstraintType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var resolvingDefaultType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + + var markerSuperType = createTypeParameter(); + var markerSubType = createTypeParameter(); + markerSubType.constraint = markerSuperType; + var markerOtherType = createTypeParameter(); + + var markerSuperTypeForCheck = createTypeParameter(); + var markerSubTypeForCheck = createTypeParameter(); + markerSubTypeForCheck.constraint = markerSuperTypeForCheck; + + var noTypePredicate = createTypePredicate(TypePredicateKind.Identifier, "<>", 0, anyType); + + var anySignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, anyType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + var unknownSignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, errorType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + var resolvingSignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, anyType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + var silentNeverSignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, silentNeverType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + + var enumNumberIndexInfo = createIndexInfo(numberType, stringType, /*isReadonly*/ true); + + var iterationTypesCache = new Map(); // cache for common IterationTypes instances + var noIterationTypes: IterationTypes = { + get yieldType(): Type { + return Debug.fail("Not supported"); + }, + get returnType(): Type { + return Debug.fail("Not supported"); + }, + get nextType(): Type { + return Debug.fail("Not supported"); + }, + }; + + var anyIterationTypes = createIterationTypes(anyType, anyType, anyType); + var anyIterationTypesExceptNext = createIterationTypes(anyType, anyType, unknownType); + var defaultIterationTypes = createIterationTypes(neverType, anyType, undefinedType); // default iteration types for `Iterator`. + + var asyncIterationTypesResolver: IterationTypesResolver = { + iterableCacheKey: "iterationTypesOfAsyncIterable", + iteratorCacheKey: "iterationTypesOfAsyncIterator", + iteratorSymbolName: "asyncIterator", + getGlobalIteratorType: getGlobalAsyncIteratorType, + getGlobalIterableType: getGlobalAsyncIterableType, + getGlobalIterableIteratorType: getGlobalAsyncIterableIteratorType, + getGlobalGeneratorType: getGlobalAsyncGeneratorType, + resolveIterationType: (type, errorNode) => getAwaitedType(type, errorNode, Diagnostics.Type_of_await_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member), + mustHaveANextMethodDiagnostic: Diagnostics.An_async_iterator_must_have_a_next_method, + mustBeAMethodDiagnostic: Diagnostics.The_0_property_of_an_async_iterator_must_be_a_method, + mustHaveAValueDiagnostic: Diagnostics.The_type_returned_by_the_0_method_of_an_async_iterator_must_be_a_promise_for_a_type_with_a_value_property, + }; + + var syncIterationTypesResolver: IterationTypesResolver = { + iterableCacheKey: "iterationTypesOfIterable", + iteratorCacheKey: "iterationTypesOfIterator", + iteratorSymbolName: "iterator", + getGlobalIteratorType, + getGlobalIterableType, + getGlobalIterableIteratorType, + getGlobalGeneratorType, + resolveIterationType: (type, _errorNode) => type, + mustHaveANextMethodDiagnostic: Diagnostics.An_iterator_must_have_a_next_method, + mustBeAMethodDiagnostic: Diagnostics.The_0_property_of_an_iterator_must_be_a_method, + mustHaveAValueDiagnostic: Diagnostics.The_type_returned_by_the_0_method_of_an_iterator_must_have_a_value_property, + }; + + interface DuplicateInfoForSymbol { + readonly firstFileLocations: Declaration[]; + readonly secondFileLocations: Declaration[]; + readonly isBlockScoped: boolean; + } + interface DuplicateInfoForFiles { + readonly firstFile: SourceFile; + readonly secondFile: SourceFile; + /** Key is symbol name. */ + readonly conflictingSymbols: Map; + } + /** Key is "/path/to/a.ts|/path/to/b.ts". */ + var amalgamatedDuplicates: Map | undefined; + var reverseMappedCache = new Map(); + var ambientModulesCache: Symbol[] | undefined; + /** + * List of every ambient module with a "*" wildcard. + * Unlike other ambient modules, these can't be stored in `globals` because symbol tables only deal with exact matches. + * This is only used if there is no exact match. + */ + var patternAmbientModules: PatternAmbientModule[]; + var patternAmbientModuleAugmentations: Map | undefined; + + var globalObjectType: ObjectType; + var globalFunctionType: ObjectType; + var globalCallableFunctionType: ObjectType; + var globalNewableFunctionType: ObjectType; + var globalArrayType: GenericType; + var globalReadonlyArrayType: GenericType; + var globalStringType: ObjectType; + var globalNumberType: ObjectType; + var globalBooleanType: ObjectType; + var globalRegExpType: ObjectType; + var globalThisType: GenericType; + var anyArrayType: Type; + var autoArrayType: Type; + var anyReadonlyArrayType: Type; + var deferredGlobalNonNullableTypeAlias: Symbol; + + // The library files are only loaded when the feature is used. + // This allows users to just specify library files they want to used through --lib + // and they will not get an error from not having unrelated library files + var deferredGlobalESSymbolConstructorSymbol: Symbol | undefined; + var deferredGlobalESSymbolConstructorTypeSymbol: Symbol | undefined; + var deferredGlobalESSymbolType: ObjectType | undefined; + var deferredGlobalTypedPropertyDescriptorType: GenericType; + var deferredGlobalPromiseType: GenericType | undefined; + var deferredGlobalPromiseLikeType: GenericType | undefined; + var deferredGlobalPromiseConstructorSymbol: Symbol | undefined; + var deferredGlobalPromiseConstructorLikeType: ObjectType | undefined; + var deferredGlobalIterableType: GenericType | undefined; + var deferredGlobalIteratorType: GenericType | undefined; + var deferredGlobalIterableIteratorType: GenericType | undefined; + var deferredGlobalGeneratorType: GenericType | undefined; + var deferredGlobalIteratorYieldResultType: GenericType | undefined; + var deferredGlobalIteratorReturnResultType: GenericType | undefined; + var deferredGlobalAsyncIterableType: GenericType | undefined; + var deferredGlobalAsyncIteratorType: GenericType | undefined; + var deferredGlobalAsyncIterableIteratorType: GenericType | undefined; + var deferredGlobalAsyncGeneratorType: GenericType | undefined; + var deferredGlobalTemplateStringsArrayType: ObjectType | undefined; + var deferredGlobalImportMetaType: ObjectType; + var deferredGlobalImportMetaExpressionType: ObjectType; + var deferredGlobalImportCallOptionsType: ObjectType | undefined; + var deferredGlobalImportAttributesType: ObjectType | undefined; + var deferredGlobalDisposableType: ObjectType | undefined; + var deferredGlobalAsyncDisposableType: ObjectType | undefined; + var deferredGlobalExtractSymbol: Symbol | undefined; + var deferredGlobalOmitSymbol: Symbol | undefined; + var deferredGlobalAwaitedSymbol: Symbol | undefined; + var deferredGlobalBigIntType: ObjectType | undefined; + var deferredGlobalNaNSymbol: Symbol | undefined; + var deferredGlobalRecordSymbol: Symbol | undefined; + var deferredGlobalClassDecoratorContextType: GenericType | undefined; + var deferredGlobalClassMethodDecoratorContextType: GenericType | undefined; + var deferredGlobalClassGetterDecoratorContextType: GenericType | undefined; + var deferredGlobalClassSetterDecoratorContextType: GenericType | undefined; + var deferredGlobalClassAccessorDecoratorContextType: GenericType | undefined; + var deferredGlobalClassAccessorDecoratorTargetType: GenericType | undefined; + var deferredGlobalClassAccessorDecoratorResultType: GenericType | undefined; + var deferredGlobalClassFieldDecoratorContextType: GenericType | undefined; + + var allPotentiallyUnusedIdentifiers = new Map(); // key is file name + + var flowLoopStart = 0; + var flowLoopCount = 0; + var sharedFlowCount = 0; + var flowAnalysisDisabled = false; + var flowInvocationCount = 0; + var lastFlowNode: FlowNode | undefined; + var lastFlowNodeReachable: boolean; + var flowTypeCache: Type[] | undefined; + + var contextualTypeNodes: Node[] = []; + var contextualTypes: (Type | undefined)[] = []; + var contextualIsCache: boolean[] = []; + var contextualTypeCount = 0; + + var inferenceContextNodes: Node[] = []; + var inferenceContexts: (InferenceContext | undefined)[] = []; + var inferenceContextCount = 0; + + var emptyStringType = getStringLiteralType(""); + var zeroType = getNumberLiteralType(0); + var zeroBigIntType = getBigIntLiteralType({ negative: false, base10Value: "0" }); + + var resolutionTargets: TypeSystemEntity[] = []; + var resolutionResults: boolean[] = []; + var resolutionPropertyNames: TypeSystemPropertyName[] = []; + var resolutionStart = 0; + var inVarianceComputation = false; + + var suggestionCount = 0; + var maximumSuggestionCount = 10; + var mergedSymbols: Symbol[] = []; + var symbolLinks: SymbolLinks[] = []; + var nodeLinks: NodeLinks[] = []; + var flowLoopCaches: Map[] = []; + var flowLoopNodes: FlowNode[] = []; + var flowLoopKeys: string[] = []; + var flowLoopTypes: Type[][] = []; + var sharedFlowNodes: FlowNode[] = []; + var sharedFlowTypes: FlowType[] = []; + var flowNodeReachable: (boolean | undefined)[] = []; + var flowNodePostSuper: (boolean | undefined)[] = []; + var potentialThisCollisions: Node[] = []; + var potentialNewTargetCollisions: Node[] = []; + var potentialWeakMapSetCollisions: Node[] = []; + var potentialReflectCollisions: Node[] = []; + var potentialUnusedRenamedBindingElementsInTypes: BindingElement[] = []; + var awaitedTypeStack: number[] = []; + var reverseMappedSourceStack: Type[] = []; + var reverseMappedTargetStack: Type[] = []; + var reverseExpandingFlags = ExpandingFlags.None; + + var diagnostics = createDiagnosticCollection(); + var suggestionDiagnostics = createDiagnosticCollection(); + + var typeofType = createTypeofType(); + + var _jsxNamespace: __String; + var _jsxFactoryEntity: EntityName | undefined; + + var subtypeRelation = new Map(); + var strictSubtypeRelation = new Map(); + var assignableRelation = new Map(); + var comparableRelation = new Map(); + var identityRelation = new Map(); + var enumRelation = new Map(); + + // Extensions suggested for path imports when module resolution is node16 or higher. + // The first element of each tuple is the extension a file has. + // The second element of each tuple is the extension that should be used in a path import. + // e.g. if we want to import file `foo.mts`, we should write `import {} from "./foo.mjs". + var suggestedExtensions: [string, string][] = [ + [".mts", ".mjs"], + [".ts", ".js"], + [".cts", ".cjs"], + [".mjs", ".mjs"], + [".js", ".js"], + [".cjs", ".cjs"], + [".tsx", compilerOptions.jsx === JsxEmit.Preserve ? ".jsx" : ".js"], + [".jsx", ".jsx"], + [".json", ".json"], + ]; + /* eslint-enable no-var */ + + initializeTypeChecker(); + + return checker; + + function isDefinitelyReferenceToGlobalSymbolObject(node: Node): boolean { + if (!isPropertyAccessExpression(node)) return false; + if (!isIdentifier(node.name)) return false; + if (!isPropertyAccessExpression(node.expression) && !isIdentifier(node.expression)) return false; + if (isIdentifier(node.expression)) { + // Exactly `Symbol.something` and `Symbol` either does not resolve or definitely resolves to the global Symbol + return idText(node.expression) === "Symbol" && getResolvedSymbol(node.expression) === (getGlobalSymbol("Symbol" as __String, SymbolFlags.Value | SymbolFlags.ExportValue, /*diagnostic*/ undefined) || unknownSymbol); + } + if (!isIdentifier(node.expression.expression)) return false; + // Exactly `globalThis.Symbol.something` and `globalThis` resolves to the global `globalThis` + return idText(node.expression.name) === "Symbol" && idText(node.expression.expression) === "globalThis" && getResolvedSymbol(node.expression.expression) === globalThisSymbol; + } + + function getCachedType(key: string | undefined) { + return key ? cachedTypes.get(key) : undefined; + } + + function setCachedType(key: string | undefined, type: Type) { + if (key) cachedTypes.set(key, type); + return type; + } + + function getJsxNamespace(location: Node | undefined): __String { + if (location) { + const file = getSourceFileOfNode(location); + if (file) { + if (isJsxOpeningFragment(location)) { + if (file.localJsxFragmentNamespace) { + return file.localJsxFragmentNamespace; + } + const jsxFragmentPragma = file.pragmas.get("jsxfrag"); + if (jsxFragmentPragma) { + const chosenPragma = isArray(jsxFragmentPragma) ? jsxFragmentPragma[0] : jsxFragmentPragma; + file.localJsxFragmentFactory = parseIsolatedEntityName(chosenPragma.arguments.factory, languageVersion); + visitNode(file.localJsxFragmentFactory, markAsSynthetic, isEntityName); + if (file.localJsxFragmentFactory) { + return file.localJsxFragmentNamespace = getFirstIdentifier(file.localJsxFragmentFactory).escapedText; + } + } + const entity = getJsxFragmentFactoryEntity(location); + if (entity) { + file.localJsxFragmentFactory = entity; + return file.localJsxFragmentNamespace = getFirstIdentifier(entity).escapedText; + } + } + else { + const localJsxNamespace = getLocalJsxNamespace(file); + if (localJsxNamespace) { + return file.localJsxNamespace = localJsxNamespace; + } + } + } + } + if (!_jsxNamespace) { + _jsxNamespace = "React" as __String; + if (compilerOptions.jsxFactory) { + _jsxFactoryEntity = parseIsolatedEntityName(compilerOptions.jsxFactory, languageVersion); + visitNode(_jsxFactoryEntity, markAsSynthetic); + if (_jsxFactoryEntity) { + _jsxNamespace = getFirstIdentifier(_jsxFactoryEntity).escapedText; + } + } + else if (compilerOptions.reactNamespace) { + _jsxNamespace = escapeLeadingUnderscores(compilerOptions.reactNamespace); + } + } + if (!_jsxFactoryEntity) { + _jsxFactoryEntity = factory.createQualifiedName(factory.createIdentifier(unescapeLeadingUnderscores(_jsxNamespace)), "createElement"); + } + return _jsxNamespace; + } + + function getLocalJsxNamespace(file: SourceFile): __String | undefined { + if (file.localJsxNamespace) { + return file.localJsxNamespace; + } + const jsxPragma = file.pragmas.get("jsx"); + if (jsxPragma) { + const chosenPragma = isArray(jsxPragma) ? jsxPragma[0] : jsxPragma; + file.localJsxFactory = parseIsolatedEntityName(chosenPragma.arguments.factory, languageVersion); + visitNode(file.localJsxFactory, markAsSynthetic, isEntityName); + if (file.localJsxFactory) { + return file.localJsxNamespace = getFirstIdentifier(file.localJsxFactory).escapedText; + } + } + } + + function markAsSynthetic(node: T): VisitResult { + setTextRangePosEnd(node, -1, -1); + return visitEachChildWorker(node, markAsSynthetic, /*context*/ undefined); + } + + function getEmitResolver(sourceFile: SourceFile, cancellationToken: CancellationToken, skipDiagnostics?: boolean) { + // Ensure we have all the type information in place for this file so that all the + // emitter questions of this resolver will return the right information. + if (!skipDiagnostics) getDiagnostics(sourceFile, cancellationToken); + return emitResolver; + } + + function lookupOrIssueError(location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + const diagnostic = location + ? createDiagnosticForNode(location, message, ...args) + : createCompilerDiagnostic(message, ...args); + const existing = diagnostics.lookup(diagnostic); + if (existing) { + return existing; + } + else { + diagnostics.add(diagnostic); + return diagnostic; + } + } + + function errorSkippedOn(key: keyof CompilerOptions, location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + const diagnostic = error(location, message, ...args); + diagnostic.skippedOn = key; + return diagnostic; + } + + function createError(location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + return location + ? createDiagnosticForNode(location, message, ...args) + : createCompilerDiagnostic(message, ...args); + } + + function error(location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + const diagnostic = createError(location, message, ...args); + diagnostics.add(diagnostic); + return diagnostic; + } + + function addErrorOrSuggestion(isError: boolean, diagnostic: Diagnostic) { + if (isError) { + diagnostics.add(diagnostic); + } + else { + suggestionDiagnostics.add({ ...diagnostic, category: DiagnosticCategory.Suggestion }); + } + } + function errorOrSuggestion(isError: boolean, location: Node, message: DiagnosticMessage | DiagnosticMessageChain, ...args: DiagnosticArguments): void { + // Pseudo-synthesized input node + if (location.pos < 0 || location.end < 0) { + if (!isError) { + return; // Drop suggestions (we have no span to suggest on) + } + // Issue errors globally + const file = getSourceFileOfNode(location); + addErrorOrSuggestion(isError, "message" in message ? createFileDiagnostic(file, 0, 0, message, ...args) : createDiagnosticForFileFromMessageChain(file, message)); // eslint-disable-line local/no-in-operator + return; + } + addErrorOrSuggestion(isError, "message" in message ? createDiagnosticForNode(location, message, ...args) : createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(location), location, message)); // eslint-disable-line local/no-in-operator + } + + function errorAndMaybeSuggestAwait( + location: Node, + maybeMissingAwait: boolean, + message: DiagnosticMessage, + ...args: DiagnosticArguments + ): Diagnostic { + const diagnostic = error(location, message, ...args); + if (maybeMissingAwait) { + const related = createDiagnosticForNode(location, Diagnostics.Did_you_forget_to_use_await); + addRelatedInfo(diagnostic, related); + } + return diagnostic; + } + + function addDeprecatedSuggestionWorker(declarations: Node | Node[], diagnostic: DiagnosticWithLocation) { + const deprecatedTag = Array.isArray(declarations) ? forEach(declarations, getJSDocDeprecatedTag) : getJSDocDeprecatedTag(declarations); + if (deprecatedTag) { + addRelatedInfo( + diagnostic, + createDiagnosticForNode(deprecatedTag, Diagnostics.The_declaration_was_marked_as_deprecated_here), + ); + } + // We call `addRelatedInfo()` before adding the diagnostic to prevent duplicates. + suggestionDiagnostics.add(diagnostic); + return diagnostic; + } + + function isDeprecatedSymbol(symbol: Symbol) { + const parentSymbol = getParentOfSymbol(symbol); + if (parentSymbol && length(symbol.declarations) > 1) { + return parentSymbol.flags & SymbolFlags.Interface ? some(symbol.declarations, isDeprecatedDeclaration) : every(symbol.declarations, isDeprecatedDeclaration); + } + return !!symbol.valueDeclaration && isDeprecatedDeclaration(symbol.valueDeclaration) + || length(symbol.declarations) && every(symbol.declarations, isDeprecatedDeclaration); + } + + function isDeprecatedDeclaration(declaration: Declaration) { + return !!(getCombinedNodeFlagsCached(declaration) & NodeFlags.Deprecated); + } + + function addDeprecatedSuggestion(location: Node, declarations: Node[], deprecatedEntity: string) { + const diagnostic = createDiagnosticForNode(location, Diagnostics._0_is_deprecated, deprecatedEntity); + return addDeprecatedSuggestionWorker(declarations, diagnostic); + } + + function addDeprecatedSuggestionWithSignature(location: Node, declaration: Node, deprecatedEntity: string | undefined, signatureString: string) { + const diagnostic = deprecatedEntity + ? createDiagnosticForNode(location, Diagnostics.The_signature_0_of_1_is_deprecated, signatureString, deprecatedEntity) + : createDiagnosticForNode(location, Diagnostics._0_is_deprecated, signatureString); + return addDeprecatedSuggestionWorker(declaration, diagnostic); + } + + function createSymbol(flags: SymbolFlags, name: __String, checkFlags?: CheckFlags) { + symbolCount++; + const symbol = new Symbol(flags | SymbolFlags.Transient, name) as TransientSymbol; + symbol.links = new SymbolLinks() as TransientSymbolLinks; + symbol.links.checkFlags = checkFlags || CheckFlags.None; + return symbol; + } + + function createParameter(name: __String, type: Type) { + const symbol = createSymbol(SymbolFlags.FunctionScopedVariable, name); + symbol.links.type = type; + return symbol; + } + + function createProperty(name: __String, type: Type) { + const symbol = createSymbol(SymbolFlags.Property, name); + symbol.links.type = type; + return symbol; + } + + function getExcludedSymbolFlags(flags: SymbolFlags): SymbolFlags { + let result: SymbolFlags = 0; + if (flags & SymbolFlags.BlockScopedVariable) result |= SymbolFlags.BlockScopedVariableExcludes; + if (flags & SymbolFlags.FunctionScopedVariable) result |= SymbolFlags.FunctionScopedVariableExcludes; + if (flags & SymbolFlags.Property) result |= SymbolFlags.PropertyExcludes; + if (flags & SymbolFlags.EnumMember) result |= SymbolFlags.EnumMemberExcludes; + if (flags & SymbolFlags.Function) result |= SymbolFlags.FunctionExcludes; + if (flags & SymbolFlags.Class) result |= SymbolFlags.ClassExcludes; + if (flags & SymbolFlags.Interface) result |= SymbolFlags.InterfaceExcludes; + if (flags & SymbolFlags.RegularEnum) result |= SymbolFlags.RegularEnumExcludes; + if (flags & SymbolFlags.ConstEnum) result |= SymbolFlags.ConstEnumExcludes; + if (flags & SymbolFlags.ValueModule) result |= SymbolFlags.ValueModuleExcludes; + if (flags & SymbolFlags.Method) result |= SymbolFlags.MethodExcludes; + if (flags & SymbolFlags.GetAccessor) result |= SymbolFlags.GetAccessorExcludes; + if (flags & SymbolFlags.SetAccessor) result |= SymbolFlags.SetAccessorExcludes; + if (flags & SymbolFlags.TypeParameter) result |= SymbolFlags.TypeParameterExcludes; + if (flags & SymbolFlags.TypeAlias) result |= SymbolFlags.TypeAliasExcludes; + if (flags & SymbolFlags.Alias) result |= SymbolFlags.AliasExcludes; + return result; + } + + function recordMergedSymbol(target: Symbol, source: Symbol) { + if (!source.mergeId) { + source.mergeId = nextMergeId; + nextMergeId++; + } + mergedSymbols[source.mergeId] = target; + } + + function cloneSymbol(symbol: Symbol): TransientSymbol { + const result = createSymbol(symbol.flags, symbol.escapedName); + result.declarations = symbol.declarations ? symbol.declarations.slice() : []; + result.parent = symbol.parent; + if (symbol.valueDeclaration) result.valueDeclaration = symbol.valueDeclaration; + if (symbol.constEnumOnlyModule) result.constEnumOnlyModule = true; + if (symbol.members) result.members = new Map(symbol.members); + if (symbol.exports) result.exports = new Map(symbol.exports); + recordMergedSymbol(result, symbol); + return result; + } + + /** + * Note: if target is transient, then it is mutable, and mergeSymbol with both mutate and return it. + * If target is not transient, mergeSymbol will produce a transient clone, mutate that and return it. + */ + function mergeSymbol(target: Symbol, source: Symbol, unidirectional = false): Symbol { + if ( + !(target.flags & getExcludedSymbolFlags(source.flags)) || + (source.flags | target.flags) & SymbolFlags.Assignment + ) { + if (source === target) { + // This can happen when an export assigned namespace exports something also erroneously exported at the top level + // See `declarationFileNoCrashOnExtraExportModifier` for an example + return target; + } + if (!(target.flags & SymbolFlags.Transient)) { + const resolvedTarget = resolveSymbol(target); + if (resolvedTarget === unknownSymbol) { + return source; + } + if ( + !(resolvedTarget.flags & getExcludedSymbolFlags(source.flags)) || + (source.flags | resolvedTarget.flags) & SymbolFlags.Assignment + ) { + target = cloneSymbol(resolvedTarget); + } + else { + reportMergeSymbolError(target, source); + return source; + } + } + // Javascript static-property-assignment declarations always merge, even though they are also values + if (source.flags & SymbolFlags.ValueModule && target.flags & SymbolFlags.ValueModule && target.constEnumOnlyModule && !source.constEnumOnlyModule) { + // reset flag when merging instantiated module into value module that has only const enums + target.constEnumOnlyModule = false; + } + target.flags |= source.flags; + if (source.valueDeclaration) { + setValueDeclaration(target, source.valueDeclaration); + } + addRange(target.declarations, source.declarations); + if (source.members) { + if (!target.members) target.members = createSymbolTable(); + mergeSymbolTable(target.members, source.members, unidirectional); + } + if (source.exports) { + if (!target.exports) target.exports = createSymbolTable(); + mergeSymbolTable(target.exports, source.exports, unidirectional); + } + if (!unidirectional) { + recordMergedSymbol(target, source); + } + } + else if (target.flags & SymbolFlags.NamespaceModule) { + // Do not report an error when merging `var globalThis` with the built-in `globalThis`, + // as we will already report a "Declaration name conflicts..." error, and this error + // won't make much sense. + if (target !== globalThisSymbol) { + error( + source.declarations && getNameOfDeclaration(source.declarations[0]), + Diagnostics.Cannot_augment_module_0_with_value_exports_because_it_resolves_to_a_non_module_entity, + symbolToString(target), + ); + } + } + else { + reportMergeSymbolError(target, source); + } + return target; + + function reportMergeSymbolError(target: Symbol, source: Symbol) { + const isEitherEnum = !!(target.flags & SymbolFlags.Enum || source.flags & SymbolFlags.Enum); + const isEitherBlockScoped = !!(target.flags & SymbolFlags.BlockScopedVariable || source.flags & SymbolFlags.BlockScopedVariable); + const message = isEitherEnum ? Diagnostics.Enum_declarations_can_only_merge_with_namespace_or_other_enum_declarations + : isEitherBlockScoped ? Diagnostics.Cannot_redeclare_block_scoped_variable_0 + : Diagnostics.Duplicate_identifier_0; + const sourceSymbolFile = source.declarations && getSourceFileOfNode(source.declarations[0]); + const targetSymbolFile = target.declarations && getSourceFileOfNode(target.declarations[0]); + + const isSourcePlainJs = isPlainJsFile(sourceSymbolFile, compilerOptions.checkJs); + const isTargetPlainJs = isPlainJsFile(targetSymbolFile, compilerOptions.checkJs); + const symbolName = symbolToString(source); + + // Collect top-level duplicate identifier errors into one mapping, so we can then merge their diagnostics if there are a bunch + if (sourceSymbolFile && targetSymbolFile && amalgamatedDuplicates && !isEitherEnum && sourceSymbolFile !== targetSymbolFile) { + const firstFile = comparePaths(sourceSymbolFile.path, targetSymbolFile.path) === Comparison.LessThan ? sourceSymbolFile : targetSymbolFile; + const secondFile = firstFile === sourceSymbolFile ? targetSymbolFile : sourceSymbolFile; + const filesDuplicates = getOrUpdate(amalgamatedDuplicates, `${firstFile.path}|${secondFile.path}`, (): DuplicateInfoForFiles => ({ firstFile, secondFile, conflictingSymbols: new Map() })); + const conflictingSymbolInfo = getOrUpdate(filesDuplicates.conflictingSymbols, symbolName, (): DuplicateInfoForSymbol => ({ isBlockScoped: isEitherBlockScoped, firstFileLocations: [], secondFileLocations: [] })); + if (!isSourcePlainJs) addDuplicateLocations(conflictingSymbolInfo.firstFileLocations, source); + if (!isTargetPlainJs) addDuplicateLocations(conflictingSymbolInfo.secondFileLocations, target); + } + else { + if (!isSourcePlainJs) addDuplicateDeclarationErrorsForSymbols(source, message, symbolName, target); + if (!isTargetPlainJs) addDuplicateDeclarationErrorsForSymbols(target, message, symbolName, source); + } + } + + function addDuplicateLocations(locs: Declaration[], symbol: Symbol): void { + if (symbol.declarations) { + for (const decl of symbol.declarations) { + pushIfUnique(locs, decl); + } + } + } + } + + function addDuplicateDeclarationErrorsForSymbols(target: Symbol, message: DiagnosticMessage, symbolName: string, source: Symbol) { + forEach(target.declarations, node => { + addDuplicateDeclarationError(node, message, symbolName, source.declarations); + }); + } + + function addDuplicateDeclarationError(node: Declaration, message: DiagnosticMessage, symbolName: string, relatedNodes: readonly Declaration[] | undefined) { + const errorNode = (getExpandoInitializer(node, /*isPrototypeAssignment*/ false) ? getNameOfExpando(node) : getNameOfDeclaration(node)) || node; + const err = lookupOrIssueError(errorNode, message, symbolName); + for (const relatedNode of relatedNodes || emptyArray) { + const adjustedNode = (getExpandoInitializer(relatedNode, /*isPrototypeAssignment*/ false) ? getNameOfExpando(relatedNode) : getNameOfDeclaration(relatedNode)) || relatedNode; + if (adjustedNode === errorNode) continue; + err.relatedInformation = err.relatedInformation || []; + const leadingMessage = createDiagnosticForNode(adjustedNode, Diagnostics._0_was_also_declared_here, symbolName); + const followOnMessage = createDiagnosticForNode(adjustedNode, Diagnostics.and_here); + if (length(err.relatedInformation) >= 5 || some(err.relatedInformation, r => compareDiagnostics(r, followOnMessage) === Comparison.EqualTo || compareDiagnostics(r, leadingMessage) === Comparison.EqualTo)) continue; + addRelatedInfo(err, !length(err.relatedInformation) ? leadingMessage : followOnMessage); + } + } + + function combineSymbolTables(first: SymbolTable | undefined, second: SymbolTable | undefined): SymbolTable | undefined { + if (!first?.size) return second; + if (!second?.size) return first; + const combined = createSymbolTable(); + mergeSymbolTable(combined, first); + mergeSymbolTable(combined, second); + return combined; + } + + function mergeSymbolTable(target: SymbolTable, source: SymbolTable, unidirectional = false) { + source.forEach((sourceSymbol, id) => { + const targetSymbol = target.get(id); + target.set(id, targetSymbol ? mergeSymbol(targetSymbol, sourceSymbol, unidirectional) : getMergedSymbol(sourceSymbol)); + }); + } + + function mergeModuleAugmentation(moduleName: StringLiteral | Identifier): void { + const moduleAugmentation = moduleName.parent as ModuleDeclaration; + if (moduleAugmentation.symbol.declarations?.[0] !== moduleAugmentation) { + // this is a combined symbol for multiple augmentations within the same file. + // its symbol already has accumulated information for all declarations + // so we need to add it just once - do the work only for first declaration + Debug.assert(moduleAugmentation.symbol.declarations!.length > 1); + return; + } + + if (isGlobalScopeAugmentation(moduleAugmentation)) { + mergeSymbolTable(globals, moduleAugmentation.symbol.exports!); + } + else { + // find a module that about to be augmented + // do not validate names of augmentations that are defined in ambient context + const moduleNotFoundError = !(moduleName.parent.parent.flags & NodeFlags.Ambient) + ? Diagnostics.Invalid_module_name_in_augmentation_module_0_cannot_be_found + : undefined; + let mainModule = resolveExternalModuleNameWorker(moduleName, moduleName, moduleNotFoundError, /*isForAugmentation*/ true); + if (!mainModule) { + return; + } + // obtain item referenced by 'export=' + mainModule = resolveExternalModuleSymbol(mainModule); + if (mainModule.flags & SymbolFlags.Namespace) { + // If we're merging an augmentation to a pattern ambient module, we want to + // perform the merge unidirectionally from the augmentation ('a.foo') to + // the pattern ('*.foo'), so that 'getMergedSymbol()' on a.foo gives you + // all the exports both from the pattern and from the augmentation, but + // 'getMergedSymbol()' on *.foo only gives you exports from *.foo. + if (some(patternAmbientModules, module => mainModule === module.symbol)) { + const merged = mergeSymbol(moduleAugmentation.symbol, mainModule, /*unidirectional*/ true); + if (!patternAmbientModuleAugmentations) { + patternAmbientModuleAugmentations = new Map(); + } + // moduleName will be a StringLiteral since this is not `declare global`. + patternAmbientModuleAugmentations.set((moduleName as StringLiteral).text, merged); + } + else { + if (mainModule.exports?.get(InternalSymbolName.ExportStar) && moduleAugmentation.symbol.exports?.size) { + // We may need to merge the module augmentation's exports into the target symbols of the resolved exports + const resolvedExports = getResolvedMembersOrExportsOfSymbol(mainModule, MembersOrExportsResolutionKind.resolvedExports); + for (const [key, value] of arrayFrom(moduleAugmentation.symbol.exports.entries())) { + if (resolvedExports.has(key) && !mainModule.exports.has(key)) { + mergeSymbol(resolvedExports.get(key)!, value); + } + } + } + mergeSymbol(mainModule, moduleAugmentation.symbol); + } + } + else { + // moduleName will be a StringLiteral since this is not `declare global`. + error(moduleName, Diagnostics.Cannot_augment_module_0_because_it_resolves_to_a_non_module_entity, (moduleName as StringLiteral).text); + } + } + } + + function addUndefinedToGlobalsOrErrorOnRedeclaration() { + const name = undefinedSymbol.escapedName; + const targetSymbol = globals.get(name); + if (targetSymbol) { + forEach(targetSymbol.declarations, declaration => { + // checkTypeNameIsReserved will have added better diagnostics for type declarations. + if (!isTypeDeclaration(declaration)) { + diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Declaration_name_conflicts_with_built_in_global_identifier_0, unescapeLeadingUnderscores(name))); + } + }); + } + else { + globals.set(name, undefinedSymbol); + } + } + + function getSymbolLinks(symbol: Symbol): SymbolLinks { + if (symbol.flags & SymbolFlags.Transient) return (symbol as TransientSymbol).links; + const id = getSymbolId(symbol); + return symbolLinks[id] ??= new SymbolLinks(); + } + + function getNodeLinks(node: Node): NodeLinks { + const nodeId = getNodeId(node); + return nodeLinks[nodeId] || (nodeLinks[nodeId] = new (NodeLinks as any)()); + } + + function getSymbol(symbols: SymbolTable, name: __String, meaning: SymbolFlags): Symbol | undefined { + if (meaning) { + const symbol = getMergedSymbol(symbols.get(name)); + if (symbol) { + if (symbol.flags & meaning) { + return symbol; + } + if (symbol.flags & SymbolFlags.Alias) { + const targetFlags = getSymbolFlags(symbol); + // `targetFlags` will be `SymbolFlags.All` if an error occurred in alias resolution; this avoids cascading errors + if (targetFlags & meaning) { + return symbol; + } + } + } + } + // return undefined if we can't find a symbol. + } + + /** + * Get symbols that represent parameter-property-declaration as parameter and as property declaration + * @param parameter a parameterDeclaration node + * @param parameterName a name of the parameter to get the symbols for. + * @return a tuple of two symbols + */ + function getSymbolsOfParameterPropertyDeclaration(parameter: ParameterPropertyDeclaration, parameterName: __String): [Symbol, Symbol] { + const constructorDeclaration = parameter.parent; + const classDeclaration = parameter.parent.parent; + + const parameterSymbol = getSymbol(constructorDeclaration.locals!, parameterName, SymbolFlags.Value); + const propertySymbol = getSymbol(getMembersOfSymbol(classDeclaration.symbol), parameterName, SymbolFlags.Value); + + if (parameterSymbol && propertySymbol) { + return [parameterSymbol, propertySymbol]; + } + + return Debug.fail("There should exist two symbols, one as property declaration and one as parameter declaration"); + } + + function isBlockScopedNameDeclaredBeforeUse(declaration: Declaration, usage: Node): boolean { + const declarationFile = getSourceFileOfNode(declaration); + const useFile = getSourceFileOfNode(usage); + const declContainer = getEnclosingBlockScopeContainer(declaration); + if (declarationFile !== useFile) { + if ( + (moduleKind && (declarationFile.externalModuleIndicator || useFile.externalModuleIndicator)) || + (!compilerOptions.outFile) || + isInTypeQuery(usage) || + declaration.flags & NodeFlags.Ambient + ) { + // nodes are in different files and order cannot be determined + return true; + } + // declaration is after usage + // can be legal if usage is deferred (i.e. inside function or in initializer of instance property) + if (isUsedInFunctionOrInstanceProperty(usage, declaration)) { + return true; + } + const sourceFiles = host.getSourceFiles(); + return sourceFiles.indexOf(declarationFile) <= sourceFiles.indexOf(useFile); + } + + // deferred usage in a type context is always OK regardless of the usage position: + if (!!(usage.flags & NodeFlags.JSDoc) || isInTypeQuery(usage) || isInAmbientOrTypeNode(usage)) { + return true; + } + + if (declaration.pos <= usage.pos && !(isPropertyDeclaration(declaration) && isThisProperty(usage.parent) && !declaration.initializer && !declaration.exclamationToken)) { + // declaration is before usage + if (declaration.kind === SyntaxKind.BindingElement) { + // still might be illegal if declaration and usage are both binding elements (eg var [a = b, b = b] = [1, 2]) + const errorBindingElement = getAncestor(usage, SyntaxKind.BindingElement) as BindingElement; + if (errorBindingElement) { + return findAncestor(errorBindingElement, isBindingElement) !== findAncestor(declaration, isBindingElement) || + declaration.pos < errorBindingElement.pos; + } + // or it might be illegal if usage happens before parent variable is declared (eg var [a] = a) + return isBlockScopedNameDeclaredBeforeUse(getAncestor(declaration, SyntaxKind.VariableDeclaration) as Declaration, usage); + } + else if (declaration.kind === SyntaxKind.VariableDeclaration) { + // still might be illegal if usage is in the initializer of the variable declaration (eg var a = a) + return !isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration as VariableDeclaration, usage); + } + else if (isClassLike(declaration)) { + // still might be illegal if the usage is within a computed property name in the class (eg class A { static p = "a"; [A.p]() {} }) + // or when used within a decorator in the class (e.g. `@dec(A.x) class A { static x = "x" }`), + // except when used in a function that is not an IIFE (e.g., `@dec(() => A.x) class A { ... }`) + const container = findAncestor(usage, n => + n === declaration ? "quit" : + isComputedPropertyName(n) ? n.parent.parent === declaration : + !legacyDecorators && isDecorator(n) && (n.parent === declaration || + isMethodDeclaration(n.parent) && n.parent.parent === declaration || + isGetOrSetAccessorDeclaration(n.parent) && n.parent.parent === declaration || + isPropertyDeclaration(n.parent) && n.parent.parent === declaration || + isParameter(n.parent) && n.parent.parent.parent === declaration)); + if (!container) { + return true; + } + if (!legacyDecorators && isDecorator(container)) { + return !!findAncestor(usage, n => n === container ? "quit" : isFunctionLike(n) && !getImmediatelyInvokedFunctionExpression(n)); + } + return false; + } + else if (isPropertyDeclaration(declaration)) { + // still might be illegal if a self-referencing property initializer (eg private x = this.x) + return !isPropertyImmediatelyReferencedWithinDeclaration(declaration, usage, /*stopAtAnyPropertyDeclaration*/ false); + } + else if (isParameterPropertyDeclaration(declaration, declaration.parent)) { + // foo = this.bar is illegal in emitStandardClassFields when bar is a parameter property + return !(emitStandardClassFields + && getContainingClass(declaration) === getContainingClass(usage) + && isUsedInFunctionOrInstanceProperty(usage, declaration)); + } + return true; + } + + // declaration is after usage, but it can still be legal if usage is deferred: + // 1. inside an export specifier + // 2. inside a function + // 3. inside an instance property initializer, a reference to a non-instance property + // (except when emitStandardClassFields: true and the reference is to a parameter property) + // 4. inside a static property initializer, a reference to a static method in the same class + // 5. inside a TS export= declaration (since we will move the export statement during emit to avoid TDZ) + if (usage.parent.kind === SyntaxKind.ExportSpecifier || (usage.parent.kind === SyntaxKind.ExportAssignment && (usage.parent as ExportAssignment).isExportEquals)) { + // export specifiers do not use the variable, they only make it available for use + return true; + } + // When resolving symbols for exports, the `usage` location passed in can be the export site directly + if (usage.kind === SyntaxKind.ExportAssignment && (usage as ExportAssignment).isExportEquals) { + return true; + } + + if (isUsedInFunctionOrInstanceProperty(usage, declaration)) { + if ( + emitStandardClassFields + && getContainingClass(declaration) + && (isPropertyDeclaration(declaration) || isParameterPropertyDeclaration(declaration, declaration.parent)) + ) { + return !isPropertyImmediatelyReferencedWithinDeclaration(declaration, usage, /*stopAtAnyPropertyDeclaration*/ true); + } + else { + return true; + } + } + return false; + + function isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration: VariableDeclaration, usage: Node): boolean { + switch (declaration.parent.parent.kind) { + case SyntaxKind.VariableStatement: + case SyntaxKind.ForStatement: + case SyntaxKind.ForOfStatement: + // variable statement/for/for-of statement case, + // use site should not be inside variable declaration (initializer of declaration or binding element) + if (isSameScopeDescendentOf(usage, declaration, declContainer)) { + return true; + } + break; + } + + // ForIn/ForOf case - use site should not be used in expression part + const grandparent = declaration.parent.parent; + return isForInOrOfStatement(grandparent) && isSameScopeDescendentOf(usage, grandparent.expression, declContainer); + } + + function isUsedInFunctionOrInstanceProperty(usage: Node, declaration: Node): boolean { + return !!findAncestor(usage, current => { + if (current === declContainer) { + return "quit"; + } + if (isFunctionLike(current)) { + return true; + } + if (isClassStaticBlockDeclaration(current)) { + return declaration.pos < usage.pos; + } + + const propertyDeclaration = tryCast(current.parent, isPropertyDeclaration); + if (propertyDeclaration) { + const initializerOfProperty = propertyDeclaration.initializer === current; + if (initializerOfProperty) { + if (isStatic(current.parent)) { + if (declaration.kind === SyntaxKind.MethodDeclaration) { + return true; + } + if (isPropertyDeclaration(declaration) && getContainingClass(usage) === getContainingClass(declaration)) { + const propName = declaration.name; + if (isIdentifier(propName) || isPrivateIdentifier(propName)) { + const type = getTypeOfSymbol(getSymbolOfDeclaration(declaration)); + const staticBlocks = filter(declaration.parent.members, isClassStaticBlockDeclaration); + if (isPropertyInitializedInStaticBlocks(propName, type, staticBlocks, declaration.parent.pos, current.pos)) { + return true; + } + } + } + } + else { + const isDeclarationInstanceProperty = declaration.kind === SyntaxKind.PropertyDeclaration && !isStatic(declaration); + if (!isDeclarationInstanceProperty || getContainingClass(usage) !== getContainingClass(declaration)) { + return true; + } + } + } + } + return false; + }); + } + + /** stopAtAnyPropertyDeclaration is used for detecting ES-standard class field use-before-def errors */ + function isPropertyImmediatelyReferencedWithinDeclaration(declaration: PropertyDeclaration | ParameterPropertyDeclaration, usage: Node, stopAtAnyPropertyDeclaration: boolean) { + // always legal if usage is after declaration + if (usage.end > declaration.end) { + return false; + } + + // still might be legal if usage is deferred (e.g. x: any = () => this.x) + // otherwise illegal if immediately referenced within the declaration (e.g. x: any = this.x) + const ancestorChangingReferenceScope = findAncestor(usage, (node: Node) => { + if (node === declaration) { + return "quit"; + } + + switch (node.kind) { + case SyntaxKind.ArrowFunction: + return true; + case SyntaxKind.PropertyDeclaration: + // even when stopping at any property declaration, they need to come from the same class + return stopAtAnyPropertyDeclaration && + (isPropertyDeclaration(declaration) && node.parent === declaration.parent + || isParameterPropertyDeclaration(declaration, declaration.parent) && node.parent === declaration.parent.parent) + ? "quit" : true; + case SyntaxKind.Block: + switch (node.parent.kind) { + case SyntaxKind.GetAccessor: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.SetAccessor: + return true; + default: + return false; + } + default: + return false; + } + }); + + return ancestorChangingReferenceScope === undefined; + } + } + + function getRequiresScopeChangeCache(node: FunctionLikeDeclaration) { + return getNodeLinks(node).declarationRequiresScopeChange; + } + function setRequiresScopeChangeCache(node: FunctionLikeDeclaration, value: boolean) { + getNodeLinks(node).declarationRequiresScopeChange = value; + } + // The invalid initializer error is needed in two situation: + // 1. When result is undefined, after checking for a missing "this." + // 2. When result is defined + function checkAndReportErrorForInvalidInitializer(errorLocation: Node | undefined, name: __String, propertyWithInvalidInitializer: PropertyDeclaration, result: Symbol | undefined) { + if (!emitStandardClassFields) { + if (errorLocation && !result && checkAndReportErrorForMissingPrefix(errorLocation, name, name)) { + return true; + } + // We have a match, but the reference occurred within a property initializer and the identifier also binds + // to a local variable in the constructor where the code will be emitted. Note that this is actually allowed + // with emitStandardClassFields because the scope semantics are different. + error( + errorLocation, + errorLocation && propertyWithInvalidInitializer.type && textRangeContainsPositionInclusive(propertyWithInvalidInitializer.type, errorLocation.pos) + ? Diagnostics.Type_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor + : Diagnostics.Initializer_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor, + declarationNameToString(propertyWithInvalidInitializer.name), + diagnosticName(name), + ); + return true; + } + return false; + } + function onFailedToResolveSymbol( + errorLocation: Node | undefined, + nameArg: __String | Identifier, + meaning: SymbolFlags, + nameNotFoundMessage: DiagnosticMessage, + ) { + const name = isString(nameArg) ? nameArg : (nameArg as Identifier).escapedText; + addLazyDiagnostic(() => { + if ( + !errorLocation || + errorLocation.parent.kind !== SyntaxKind.JSDocLink && + !checkAndReportErrorForMissingPrefix(errorLocation, name, nameArg) && + !checkAndReportErrorForExtendingInterface(errorLocation) && + !checkAndReportErrorForUsingTypeAsNamespace(errorLocation, name, meaning) && + !checkAndReportErrorForExportingPrimitiveType(errorLocation, name) && + !checkAndReportErrorForUsingNamespaceAsTypeOrValue(errorLocation, name, meaning) && + !checkAndReportErrorForUsingTypeAsValue(errorLocation, name, meaning) && + !checkAndReportErrorForUsingValueAsType(errorLocation, name, meaning) + ) { + let suggestion: Symbol | undefined; + let suggestedLib: string | undefined; + // Report missing lib first + if (nameArg) { + suggestedLib = getSuggestedLibForNonExistentName(nameArg); + if (suggestedLib) { + error(errorLocation, nameNotFoundMessage, diagnosticName(nameArg), suggestedLib); + } + } + // then spelling suggestions + if (!suggestedLib && suggestionCount < maximumSuggestionCount) { + suggestion = getSuggestedSymbolForNonexistentSymbol(errorLocation, name, meaning); + const isGlobalScopeAugmentationDeclaration = suggestion?.valueDeclaration && isAmbientModule(suggestion.valueDeclaration) && isGlobalScopeAugmentation(suggestion.valueDeclaration); + if (isGlobalScopeAugmentationDeclaration) { + suggestion = undefined; + } + if (suggestion) { + const suggestionName = symbolToString(suggestion); + const isUncheckedJS = isUncheckedJSSuggestion(errorLocation, suggestion, /*excludeClasses*/ false); + const message = meaning === SymbolFlags.Namespace || + nameArg && typeof nameArg !== "string" && nodeIsSynthesized(nameArg) ? + Diagnostics.Cannot_find_namespace_0_Did_you_mean_1 + : isUncheckedJS ? Diagnostics.Could_not_find_name_0_Did_you_mean_1 + : Diagnostics.Cannot_find_name_0_Did_you_mean_1; + const diagnostic = createError(errorLocation, message, diagnosticName(nameArg), suggestionName); + diagnostic.canonicalHead = getCanonicalDiagnostic(nameNotFoundMessage, diagnosticName(nameArg)); + addErrorOrSuggestion(!isUncheckedJS, diagnostic); + if (suggestion.valueDeclaration) { + addRelatedInfo( + diagnostic, + createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestionName), + ); + } + } + } + // And then fall back to unspecified "not found" + if (!suggestion && !suggestedLib && nameArg) { + error(errorLocation, nameNotFoundMessage, diagnosticName(nameArg)); + } + suggestionCount++; + } + }); + } + + function onSuccessfullyResolvedSymbol( + errorLocation: Node | undefined, + result: Symbol, + meaning: SymbolFlags, + lastLocation: Node | undefined, + associatedDeclarationForContainingInitializerOrBindingName: ParameterDeclaration | BindingElement | undefined, + withinDeferredContext: boolean, + ) { + addLazyDiagnostic(() => { + const name = result.escapedName; + const isInExternalModule = lastLocation && isSourceFile(lastLocation) && isExternalOrCommonJsModule(lastLocation); + // Only check for block-scoped variable if we have an error location and are looking for the + // name with variable meaning + // For example, + // declare module foo { + // interface bar {} + // } + // const foo/*1*/: foo/*2*/.bar; + // The foo at /*1*/ and /*2*/ will share same symbol with two meanings: + // block-scoped variable and namespace module. However, only when we + // try to resolve name in /*1*/ which is used in variable position, + // we want to check for block-scoped + if ( + errorLocation && + (meaning & SymbolFlags.BlockScopedVariable || + ((meaning & SymbolFlags.Class || meaning & SymbolFlags.Enum) && (meaning & SymbolFlags.Value) === SymbolFlags.Value)) + ) { + const exportOrLocalSymbol = getExportSymbolOfValueSymbolIfExported(result); + if (exportOrLocalSymbol.flags & SymbolFlags.BlockScopedVariable || exportOrLocalSymbol.flags & SymbolFlags.Class || exportOrLocalSymbol.flags & SymbolFlags.Enum) { + checkResolvedBlockScopedVariable(exportOrLocalSymbol, errorLocation); + } + } + + // If we're in an external module, we can't reference value symbols created from UMD export declarations + if (isInExternalModule && (meaning & SymbolFlags.Value) === SymbolFlags.Value && !(errorLocation!.flags & NodeFlags.JSDoc)) { + const merged = getMergedSymbol(result); + if (length(merged.declarations) && every(merged.declarations, d => isNamespaceExportDeclaration(d) || isSourceFile(d) && !!d.symbol.globalExports)) { + errorOrSuggestion(!compilerOptions.allowUmdGlobalAccess, errorLocation!, Diagnostics._0_refers_to_a_UMD_global_but_the_current_file_is_a_module_Consider_adding_an_import_instead, unescapeLeadingUnderscores(name)); + } + } + + // If we're in a parameter initializer or binding name, we can't reference the values of the parameter whose initializer we're within or parameters to the right + if (associatedDeclarationForContainingInitializerOrBindingName && !withinDeferredContext && (meaning & SymbolFlags.Value) === SymbolFlags.Value) { + const candidate = getMergedSymbol(getLateBoundSymbol(result)); + const root = getRootDeclaration(associatedDeclarationForContainingInitializerOrBindingName) as ParameterDeclaration; + // A parameter initializer or binding pattern initializer within a parameter cannot refer to itself + if (candidate === getSymbolOfDeclaration(associatedDeclarationForContainingInitializerOrBindingName)) { + error(errorLocation, Diagnostics.Parameter_0_cannot_reference_itself, declarationNameToString(associatedDeclarationForContainingInitializerOrBindingName.name)); + } + // And it cannot refer to any declarations which come after it + else if (candidate.valueDeclaration && candidate.valueDeclaration.pos > associatedDeclarationForContainingInitializerOrBindingName.pos && root.parent.locals && getSymbol(root.parent.locals, candidate.escapedName, meaning) === candidate) { + error(errorLocation, Diagnostics.Parameter_0_cannot_reference_identifier_1_declared_after_it, declarationNameToString(associatedDeclarationForContainingInitializerOrBindingName.name), declarationNameToString(errorLocation as Identifier)); + } + } + if (errorLocation && meaning & SymbolFlags.Value && result.flags & SymbolFlags.Alias && !(result.flags & SymbolFlags.Value) && !isValidTypeOnlyAliasUseSite(errorLocation)) { + const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(result, SymbolFlags.Value); + if (typeOnlyDeclaration) { + const message = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration || typeOnlyDeclaration.kind === SyntaxKind.NamespaceExport + ? Diagnostics._0_cannot_be_used_as_a_value_because_it_was_exported_using_export_type + : Diagnostics._0_cannot_be_used_as_a_value_because_it_was_imported_using_import_type; + const unescapedName = unescapeLeadingUnderscores(name); + addTypeOnlyDeclarationRelatedInfo( + error(errorLocation, message, unescapedName), + typeOnlyDeclaration, + unescapedName, + ); + } + } + + // Look at 'compilerOptions.isolatedModules' and not 'getIsolatedModules(...)' (which considers 'verbatimModuleSyntax') + // here because 'verbatimModuleSyntax' will already have an error for importing a type without 'import type'. + if (compilerOptions.isolatedModules && result && isInExternalModule && (meaning & SymbolFlags.Value) === SymbolFlags.Value) { + const isGlobal = getSymbol(globals, name, meaning) === result; + const nonValueSymbol = isGlobal && isSourceFile(lastLocation) && lastLocation.locals && getSymbol(lastLocation.locals, name, ~SymbolFlags.Value); + if (nonValueSymbol) { + const importDecl = nonValueSymbol.declarations?.find(d => d.kind === SyntaxKind.ImportSpecifier || d.kind === SyntaxKind.ImportClause || d.kind === SyntaxKind.NamespaceImport || d.kind === SyntaxKind.ImportEqualsDeclaration); + if (importDecl && !isTypeOnlyImportDeclaration(importDecl)) { + error(importDecl, Diagnostics.Import_0_conflicts_with_global_value_used_in_this_file_so_must_be_declared_with_a_type_only_import_when_isolatedModules_is_enabled, unescapeLeadingUnderscores(name)); + } + } + } + }); + } + + function addTypeOnlyDeclarationRelatedInfo(diagnostic: Diagnostic, typeOnlyDeclaration: TypeOnlyCompatibleAliasDeclaration | undefined, unescapedName: string) { + if (!typeOnlyDeclaration) return diagnostic; + return addRelatedInfo( + diagnostic, + createDiagnosticForNode( + typeOnlyDeclaration, + typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration || typeOnlyDeclaration.kind === SyntaxKind.NamespaceExport + ? Diagnostics._0_was_exported_here + : Diagnostics._0_was_imported_here, + unescapedName, + ), + ); + } + + function diagnosticName(nameArg: __String | Identifier | PrivateIdentifier) { + return isString(nameArg) ? unescapeLeadingUnderscores(nameArg as __String) : declarationNameToString(nameArg as Identifier); + } + + function checkAndReportErrorForMissingPrefix(errorLocation: Node, name: __String, nameArg: __String | Identifier): boolean { + if (!isIdentifier(errorLocation) || errorLocation.escapedText !== name || isTypeReferenceIdentifier(errorLocation) || isInTypeQuery(errorLocation)) { + return false; + } + + const container = getThisContainer(errorLocation, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + let location: Node = container; + while (location) { + if (isClassLike(location.parent)) { + const classSymbol = getSymbolOfDeclaration(location.parent); + if (!classSymbol) { + break; + } + + // Check to see if a static member exists. + const constructorType = getTypeOfSymbol(classSymbol); + if (getPropertyOfType(constructorType, name)) { + error(errorLocation, Diagnostics.Cannot_find_name_0_Did_you_mean_the_static_member_1_0, diagnosticName(nameArg), symbolToString(classSymbol)); + return true; + } + + // No static member is present. + // Check if we're in an instance method and look for a relevant instance member. + if (location === container && !isStatic(location)) { + const instanceType = (getDeclaredTypeOfSymbol(classSymbol) as InterfaceType).thisType!; // TODO: GH#18217 + if (getPropertyOfType(instanceType, name)) { + error(errorLocation, Diagnostics.Cannot_find_name_0_Did_you_mean_the_instance_member_this_0, diagnosticName(nameArg)); + return true; + } + } + } + + location = location.parent; + } + return false; + } + + function checkAndReportErrorForExtendingInterface(errorLocation: Node): boolean { + const expression = getEntityNameForExtendingInterface(errorLocation); + if (expression && resolveEntityName(expression, SymbolFlags.Interface, /*ignoreErrors*/ true)) { + error(errorLocation, Diagnostics.Cannot_extend_an_interface_0_Did_you_mean_implements, getTextOfNode(expression)); + return true; + } + return false; + } + /** + * Climbs up parents to an ExpressionWithTypeArguments, and returns its expression, + * but returns undefined if that expression is not an EntityNameExpression. + */ + function getEntityNameForExtendingInterface(node: Node): EntityNameExpression | undefined { + switch (node.kind) { + case SyntaxKind.Identifier: + case SyntaxKind.PropertyAccessExpression: + return node.parent ? getEntityNameForExtendingInterface(node.parent) : undefined; + case SyntaxKind.ExpressionWithTypeArguments: + if (isEntityNameExpression((node as ExpressionWithTypeArguments).expression)) { + return (node as ExpressionWithTypeArguments).expression as EntityNameExpression; + } + // falls through + default: + return undefined; + } + } + + function checkAndReportErrorForUsingTypeAsNamespace(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + const namespaceMeaning = SymbolFlags.Namespace | (isInJSFile(errorLocation) ? SymbolFlags.Value : 0); + if (meaning === namespaceMeaning) { + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Type & ~namespaceMeaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + const parent = errorLocation.parent; + if (symbol) { + if (isQualifiedName(parent)) { + Debug.assert(parent.left === errorLocation, "Should only be resolving left side of qualified name as a namespace"); + const propName = parent.right.escapedText; + const propType = getPropertyOfType(getDeclaredTypeOfSymbol(symbol), propName); + if (propType) { + error( + parent, + Diagnostics.Cannot_access_0_1_because_0_is_a_type_but_not_a_namespace_Did_you_mean_to_retrieve_the_type_of_the_property_1_in_0_with_0_1, + unescapeLeadingUnderscores(name), + unescapeLeadingUnderscores(propName), + ); + return true; + } + } + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_namespace_here, unescapeLeadingUnderscores(name)); + return true; + } + } + + return false; + } + + function checkAndReportErrorForUsingValueAsType(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + if (meaning & (SymbolFlags.Type & ~SymbolFlags.Namespace)) { + const symbol = resolveSymbol(resolveName(errorLocation, name, ~SymbolFlags.Type & SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + if (symbol && !(symbol.flags & SymbolFlags.Namespace)) { + error(errorLocation, Diagnostics._0_refers_to_a_value_but_is_being_used_as_a_type_here_Did_you_mean_typeof_0, unescapeLeadingUnderscores(name)); + return true; + } + } + return false; + } + + function isPrimitiveTypeName(name: __String) { + return name === "any" || name === "string" || name === "number" || name === "boolean" || name === "never" || name === "unknown"; + } + + function checkAndReportErrorForExportingPrimitiveType(errorLocation: Node, name: __String): boolean { + if (isPrimitiveTypeName(name) && errorLocation.parent.kind === SyntaxKind.ExportSpecifier) { + error(errorLocation, Diagnostics.Cannot_export_0_Only_local_declarations_can_be_exported_from_a_module, name as string); + return true; + } + return false; + } + + function checkAndReportErrorForUsingTypeAsValue(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + if (meaning & SymbolFlags.Value) { + if (isPrimitiveTypeName(name)) { + const grandparent = errorLocation.parent.parent; + if (grandparent && grandparent.parent && isHeritageClause(grandparent)) { + const heritageKind = grandparent.token; + const containerKind = grandparent.parent.kind; + if (containerKind === SyntaxKind.InterfaceDeclaration && heritageKind === SyntaxKind.ExtendsKeyword) { + error(errorLocation, Diagnostics.An_interface_cannot_extend_a_primitive_type_like_0_It_can_only_extend_other_named_object_types, unescapeLeadingUnderscores(name)); + } + else if (containerKind === SyntaxKind.ClassDeclaration && heritageKind === SyntaxKind.ExtendsKeyword) { + error(errorLocation, Diagnostics.A_class_cannot_extend_a_primitive_type_like_0_Classes_can_only_extend_constructable_values, unescapeLeadingUnderscores(name)); + } + else if (containerKind === SyntaxKind.ClassDeclaration && heritageKind === SyntaxKind.ImplementsKeyword) { + error(errorLocation, Diagnostics.A_class_cannot_implement_a_primitive_type_like_0_It_can_only_implement_other_named_object_types, unescapeLeadingUnderscores(name)); + } + } + else { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here, unescapeLeadingUnderscores(name)); + } + return true; + } + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Type & ~SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + const allFlags = symbol && getSymbolFlags(symbol); + if (symbol && allFlags !== undefined && !(allFlags & SymbolFlags.Value)) { + const rawName = unescapeLeadingUnderscores(name); + if (isES2015OrLaterConstructorName(name)) { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_es2015_or_later, rawName); + } + else if (maybeMappedType(errorLocation, symbol)) { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here_Did_you_mean_to_use_1_in_0, rawName, rawName === "K" ? "P" : "K"); + } + else { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here, rawName); + } + return true; + } + } + return false; + } + + function maybeMappedType(node: Node, symbol: Symbol) { + const container = findAncestor(node.parent, n => isComputedPropertyName(n) || isPropertySignature(n) ? false : isTypeLiteralNode(n) || "quit") as TypeLiteralNode | undefined; + if (container && container.members.length === 1) { + const type = getDeclaredTypeOfSymbol(symbol); + return !!(type.flags & TypeFlags.Union) && allTypesAssignableToKind(type, TypeFlags.StringOrNumberLiteral, /*strict*/ true); + } + return false; + } + + function isES2015OrLaterConstructorName(n: __String) { + switch (n) { + case "Promise": + case "Symbol": + case "Map": + case "WeakMap": + case "Set": + case "WeakSet": + return true; + } + return false; + } + + function checkAndReportErrorForUsingNamespaceAsTypeOrValue(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + if (meaning & (SymbolFlags.Value & ~SymbolFlags.Type)) { + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.NamespaceModule, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + if (symbol) { + error( + errorLocation, + Diagnostics.Cannot_use_namespace_0_as_a_value, + unescapeLeadingUnderscores(name), + ); + return true; + } + } + else if (meaning & (SymbolFlags.Type & ~SymbolFlags.Value)) { + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Module, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + if (symbol) { + error(errorLocation, Diagnostics.Cannot_use_namespace_0_as_a_type, unescapeLeadingUnderscores(name)); + return true; + } + } + return false; + } + + function checkResolvedBlockScopedVariable(result: Symbol, errorLocation: Node): void { + Debug.assert(!!(result.flags & SymbolFlags.BlockScopedVariable || result.flags & SymbolFlags.Class || result.flags & SymbolFlags.Enum)); + if (result.flags & (SymbolFlags.Function | SymbolFlags.FunctionScopedVariable | SymbolFlags.Assignment) && result.flags & SymbolFlags.Class) { + // constructor functions aren't block scoped + return; + } + // Block-scoped variables cannot be used before their definition + const declaration = result.declarations?.find( + d => isBlockOrCatchScoped(d) || isClassLike(d) || (d.kind === SyntaxKind.EnumDeclaration), + ); + + if (declaration === undefined) return Debug.fail("checkResolvedBlockScopedVariable could not find block-scoped declaration"); + + if (!(declaration.flags & NodeFlags.Ambient) && !isBlockScopedNameDeclaredBeforeUse(declaration, errorLocation)) { + let diagnosticMessage; + const declarationName = declarationNameToString(getNameOfDeclaration(declaration)); + if (result.flags & SymbolFlags.BlockScopedVariable) { + diagnosticMessage = error(errorLocation, Diagnostics.Block_scoped_variable_0_used_before_its_declaration, declarationName); + } + else if (result.flags & SymbolFlags.Class) { + diagnosticMessage = error(errorLocation, Diagnostics.Class_0_used_before_its_declaration, declarationName); + } + else if (result.flags & SymbolFlags.RegularEnum) { + diagnosticMessage = error(errorLocation, Diagnostics.Enum_0_used_before_its_declaration, declarationName); + } + else { + Debug.assert(!!(result.flags & SymbolFlags.ConstEnum)); + if (getIsolatedModules(compilerOptions)) { + diagnosticMessage = error(errorLocation, Diagnostics.Enum_0_used_before_its_declaration, declarationName); + } + } + + if (diagnosticMessage) { + addRelatedInfo(diagnosticMessage, createDiagnosticForNode(declaration, Diagnostics._0_is_declared_here, declarationName)); + } + } + } + + /* Starting from 'initial' node walk up the parent chain until 'stopAt' node is reached. + * If at any point current node is equal to 'parent' node - return true. + * If current node is an IIFE, continue walking up. + * Return false if 'stopAt' node is reached or isFunctionLike(current) === true. + */ + function isSameScopeDescendentOf(initial: Node, parent: Node | undefined, stopAt: Node): boolean { + return !!parent && !!findAncestor(initial, n => + n === parent + || (n === stopAt || isFunctionLike(n) && (!getImmediatelyInvokedFunctionExpression(n) || (getFunctionFlags(n) & FunctionFlags.AsyncGenerator)) ? "quit" : false)); + } + + function getAnyImportSyntax(node: Node): AnyImportOrJsDocImport | undefined { + switch (node.kind) { + case SyntaxKind.ImportEqualsDeclaration: + return node as ImportEqualsDeclaration; + case SyntaxKind.ImportClause: + return (node as ImportClause).parent; + case SyntaxKind.NamespaceImport: + return (node as NamespaceImport).parent.parent; + case SyntaxKind.ImportSpecifier: + return (node as ImportSpecifier).parent.parent.parent; + default: + return undefined; + } + } + + function getDeclarationOfAliasSymbol(symbol: Symbol): Declaration | undefined { + return symbol.declarations && findLast(symbol.declarations, isAliasSymbolDeclaration); + } + + /** + * An alias symbol is created by one of the following declarations: + * import = ... + * import from ... + * import * as from ... + * import { x as } from ... + * export { x as } from ... + * export * as ns from ... + * export = + * export default + * module.exports = + * {} + * {name: } + * const { x } = require ... + */ + function isAliasSymbolDeclaration(node: Node): boolean { + return node.kind === SyntaxKind.ImportEqualsDeclaration + || node.kind === SyntaxKind.NamespaceExportDeclaration + || node.kind === SyntaxKind.ImportClause && !!(node as ImportClause).name + || node.kind === SyntaxKind.NamespaceImport + || node.kind === SyntaxKind.NamespaceExport + || node.kind === SyntaxKind.ImportSpecifier + || node.kind === SyntaxKind.ExportSpecifier + || node.kind === SyntaxKind.ExportAssignment && exportAssignmentIsAlias(node as ExportAssignment) + || isBinaryExpression(node) && getAssignmentDeclarationKind(node) === AssignmentDeclarationKind.ModuleExports && exportAssignmentIsAlias(node) + || isAccessExpression(node) + && isBinaryExpression(node.parent) + && node.parent.left === node + && node.parent.operatorToken.kind === SyntaxKind.EqualsToken + && isAliasableOrJsExpression(node.parent.right) + || node.kind === SyntaxKind.ShorthandPropertyAssignment + || node.kind === SyntaxKind.PropertyAssignment && isAliasableOrJsExpression((node as PropertyAssignment).initializer) + || node.kind === SyntaxKind.VariableDeclaration && isVariableDeclarationInitializedToBareOrAccessedRequire(node) + || node.kind === SyntaxKind.BindingElement && isVariableDeclarationInitializedToBareOrAccessedRequire(node.parent.parent); + } + + function isAliasableOrJsExpression(e: Expression) { + return isAliasableExpression(e) || isFunctionExpression(e) && isJSConstructor(e); + } + + function getTargetOfImportEqualsDeclaration(node: ImportEqualsDeclaration | VariableDeclaration, dontResolveAlias: boolean): Symbol | undefined { + const commonJSPropertyAccess = getCommonJSPropertyAccess(node); + if (commonJSPropertyAccess) { + const name = (getLeftmostAccessExpression(commonJSPropertyAccess.expression) as CallExpression).arguments[0] as StringLiteral; + return isIdentifier(commonJSPropertyAccess.name) + ? resolveSymbol(getPropertyOfType(resolveExternalModuleTypeByLiteral(name), commonJSPropertyAccess.name.escapedText)) + : undefined; + } + if (isVariableDeclaration(node) || node.moduleReference.kind === SyntaxKind.ExternalModuleReference) { + const immediate = resolveExternalModuleName( + node, + getExternalModuleRequireArgument(node) || getExternalModuleImportEqualsDeclarationExpression(node), + ); + const resolved = resolveExternalModuleSymbol(immediate); + markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); + return resolved; + } + const resolved = getSymbolOfPartOfRightHandSideOfImportEquals(node.moduleReference, dontResolveAlias); + checkAndReportErrorForResolvingImportAliasToTypeOnlySymbol(node, resolved); + return resolved; + } + + function checkAndReportErrorForResolvingImportAliasToTypeOnlySymbol(node: ImportEqualsDeclaration, resolved: Symbol | undefined) { + if (markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false) && !node.isTypeOnly) { + const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(getSymbolOfDeclaration(node))!; + const isExport = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration; + const message = isExport + ? Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_exported_using_export_type + : Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_imported_using_import_type; + const relatedMessage = isExport + ? Diagnostics._0_was_exported_here + : Diagnostics._0_was_imported_here; + + // TODO: how to get name for export *? + const name = typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration ? "*" : moduleExportNameTextUnescaped(typeOnlyDeclaration.name); + addRelatedInfo(error(node.moduleReference, message), createDiagnosticForNode(typeOnlyDeclaration, relatedMessage, name)); + } + } + + function resolveExportByName(moduleSymbol: Symbol, name: __String, sourceNode: TypeOnlyCompatibleAliasDeclaration | undefined, dontResolveAlias: boolean) { + const exportValue = moduleSymbol.exports!.get(InternalSymbolName.ExportEquals); + const exportSymbol = exportValue + ? getPropertyOfType(getTypeOfSymbol(exportValue), name, /*skipObjectFunctionPropertyAugment*/ true) + : moduleSymbol.exports!.get(name); + const resolved = resolveSymbol(exportSymbol, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(sourceNode, exportSymbol, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function isSyntacticDefault(node: Node) { + return ((isExportAssignment(node) && !node.isExportEquals) + || hasSyntacticModifier(node, ModifierFlags.Default) + || isExportSpecifier(node) + || isNamespaceExport(node)); + } + + function getUsageModeForExpression(usage: Expression) { + return isStringLiteralLike(usage) ? host.getModeForUsageLocation(getSourceFileOfNode(usage), usage) : undefined; + } + + function isESMFormatImportImportingCommonjsFormatFile(usageMode: ResolutionMode, targetMode: ResolutionMode) { + return usageMode === ModuleKind.ESNext && targetMode === ModuleKind.CommonJS; + } + + function isOnlyImportedAsDefault(usage: Expression) { + const usageMode = getUsageModeForExpression(usage); + return usageMode === ModuleKind.ESNext && endsWith((usage as StringLiteralLike).text, Extension.Json); + } + + function canHaveSyntheticDefault(file: SourceFile | undefined, moduleSymbol: Symbol, dontResolveAlias: boolean, usage: Expression) { + const usageMode = file && getUsageModeForExpression(usage); + if (file && usageMode !== undefined && ModuleKind.Node16 <= moduleKind && moduleKind <= ModuleKind.NodeNext) { + const result = isESMFormatImportImportingCommonjsFormatFile(usageMode, file.impliedNodeFormat); + if (usageMode === ModuleKind.ESNext || result) { + return result; + } + // fallthrough on cjs usages so we imply defaults for interop'd imports, too + } + if (!allowSyntheticDefaultImports) { + return false; + } + // Declaration files (and ambient modules) + if (!file || file.isDeclarationFile) { + // Definitely cannot have a synthetic default if they have a syntactic default member specified + const defaultExportSymbol = resolveExportByName(moduleSymbol, InternalSymbolName.Default, /*sourceNode*/ undefined, /*dontResolveAlias*/ true); // Dont resolve alias because we want the immediately exported symbol's declaration + if (defaultExportSymbol && some(defaultExportSymbol.declarations, isSyntacticDefault)) { + return false; + } + // It _might_ still be incorrect to assume there is no __esModule marker on the import at runtime, even if there is no `default` member + // So we check a bit more, + if (resolveExportByName(moduleSymbol, escapeLeadingUnderscores("__esModule"), /*sourceNode*/ undefined, dontResolveAlias)) { + // If there is an `__esModule` specified in the declaration (meaning someone explicitly added it or wrote it in their code), + // it definitely is a module and does not have a synthetic default + return false; + } + // There are _many_ declaration files not written with esmodules in mind that still get compiled into a format with __esModule set + // Meaning there may be no default at runtime - however to be on the permissive side, we allow access to a synthetic default member + // as there is no marker to indicate if the accompanying JS has `__esModule` or not, or is even native esm + return true; + } + // TypeScript files never have a synthetic default (as they are always emitted with an __esModule marker) _unless_ they contain an export= statement + if (!isSourceFileJS(file)) { + return hasExportAssignmentSymbol(moduleSymbol); + } + // JS files have a synthetic default if they do not contain ES2015+ module syntax (export = is not valid in js) _and_ do not have an __esModule marker + return typeof file.externalModuleIndicator !== "object" && !resolveExportByName(moduleSymbol, escapeLeadingUnderscores("__esModule"), /*sourceNode*/ undefined, dontResolveAlias); + } + + function getTargetOfImportClause(node: ImportClause, dontResolveAlias: boolean): Symbol | undefined { + const moduleSymbol = resolveExternalModuleName(node, node.parent.moduleSpecifier); + if (moduleSymbol) { + return getTargetofModuleDefault(moduleSymbol, node, dontResolveAlias); + } + } + + function getTargetofModuleDefault(moduleSymbol: Symbol, node: ImportClause | ImportOrExportSpecifier, dontResolveAlias: boolean) { + let exportDefaultSymbol: Symbol | undefined; + if (isShorthandAmbientModuleSymbol(moduleSymbol)) { + exportDefaultSymbol = moduleSymbol; + } + else { + exportDefaultSymbol = resolveExportByName(moduleSymbol, InternalSymbolName.Default, node, dontResolveAlias); + } + + const file = moduleSymbol.declarations?.find(isSourceFile); + const specifier = getModuleSpecifierForImportOrExport(node); + if (!specifier) { + return exportDefaultSymbol; + } + const hasDefaultOnly = isOnlyImportedAsDefault(specifier); + const hasSyntheticDefault = canHaveSyntheticDefault(file, moduleSymbol, dontResolveAlias, specifier); + if (!exportDefaultSymbol && !hasSyntheticDefault && !hasDefaultOnly) { + if (hasExportAssignmentSymbol(moduleSymbol) && !allowSyntheticDefaultImports) { + const compilerOptionName = moduleKind >= ModuleKind.ES2015 ? "allowSyntheticDefaultImports" : "esModuleInterop"; + const exportEqualsSymbol = moduleSymbol.exports!.get(InternalSymbolName.ExportEquals); + const exportAssignment = exportEqualsSymbol!.valueDeclaration; + const err = error(node.name, Diagnostics.Module_0_can_only_be_default_imported_using_the_1_flag, symbolToString(moduleSymbol), compilerOptionName); + + if (exportAssignment) { + addRelatedInfo( + err, + createDiagnosticForNode( + exportAssignment, + Diagnostics.This_module_is_declared_with_export_and_can_only_be_used_with_a_default_import_when_using_the_0_flag, + compilerOptionName, + ), + ); + } + } + else if (isImportClause(node)) { + reportNonDefaultExport(moduleSymbol, node); + } + else { + errorNoModuleMemberSymbol(moduleSymbol, moduleSymbol, node, isImportOrExportSpecifier(node) && node.propertyName || node.name); + } + } + else if (hasSyntheticDefault || hasDefaultOnly) { + // per emit behavior, a synthetic default overrides a "real" .default member if `__esModule` is not present + const resolved = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias) || resolveSymbol(moduleSymbol, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, moduleSymbol, resolved, /*overwriteEmpty*/ false); + return resolved; + } + markSymbolOfAliasDeclarationIfTypeOnly(node, exportDefaultSymbol, /*finalTarget*/ undefined, /*overwriteEmpty*/ false); + return exportDefaultSymbol; + } + + function getModuleSpecifierForImportOrExport(node: ImportEqualsDeclaration | ImportClause | NamespaceImport | ImportOrExportSpecifier): Expression | undefined { + switch (node.kind) { + case SyntaxKind.ImportClause: + return node.parent.moduleSpecifier; + case SyntaxKind.ImportEqualsDeclaration: + return isExternalModuleReference(node.moduleReference) ? node.moduleReference.expression : undefined; + case SyntaxKind.NamespaceImport: + return node.parent.parent.moduleSpecifier; + case SyntaxKind.ImportSpecifier: + return node.parent.parent.parent.moduleSpecifier; + case SyntaxKind.ExportSpecifier: + return node.parent.parent.moduleSpecifier; + default: + return Debug.assertNever(node); + } + } + + function reportNonDefaultExport(moduleSymbol: Symbol, node: ImportClause) { + if (moduleSymbol.exports?.has(node.symbol.escapedName)) { + error( + node.name, + Diagnostics.Module_0_has_no_default_export_Did_you_mean_to_use_import_1_from_0_instead, + symbolToString(moduleSymbol), + symbolToString(node.symbol), + ); + } + else { + const diagnostic = error(node.name, Diagnostics.Module_0_has_no_default_export, symbolToString(moduleSymbol)); + const exportStar = moduleSymbol.exports?.get(InternalSymbolName.ExportStar); + if (exportStar) { + const defaultExport = exportStar.declarations?.find(decl => + !!( + isExportDeclaration(decl) && decl.moduleSpecifier && + resolveExternalModuleName(decl, decl.moduleSpecifier)?.exports?.has(InternalSymbolName.Default) + ) + ); + if (defaultExport) { + addRelatedInfo(diagnostic, createDiagnosticForNode(defaultExport, Diagnostics.export_Asterisk_does_not_re_export_a_default)); + } + } + } + } + + function getTargetOfNamespaceImport(node: NamespaceImport, dontResolveAlias: boolean): Symbol | undefined { + const moduleSpecifier = node.parent.parent.moduleSpecifier; + const immediate = resolveExternalModuleName(node, moduleSpecifier); + const resolved = resolveESModuleSymbol(immediate, moduleSpecifier, dontResolveAlias, /*suppressInteropError*/ false); + markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getTargetOfNamespaceExport(node: NamespaceExport, dontResolveAlias: boolean): Symbol | undefined { + const moduleSpecifier = node.parent.moduleSpecifier; + const immediate = moduleSpecifier && resolveExternalModuleName(node, moduleSpecifier); + const resolved = moduleSpecifier && resolveESModuleSymbol(immediate, moduleSpecifier, dontResolveAlias, /*suppressInteropError*/ false); + markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + // This function creates a synthetic symbol that combines the value side of one symbol with the + // type/namespace side of another symbol. Consider this example: + // + // declare module graphics { + // interface Point { + // x: number; + // y: number; + // } + // } + // declare var graphics: { + // Point: new (x: number, y: number) => graphics.Point; + // } + // declare module "graphics" { + // export = graphics; + // } + // + // An 'import { Point } from "graphics"' needs to create a symbol that combines the value side 'Point' + // property with the type/namespace side interface 'Point'. + function combineValueAndTypeSymbols(valueSymbol: Symbol, typeSymbol: Symbol): Symbol { + if (valueSymbol === unknownSymbol && typeSymbol === unknownSymbol) { + return unknownSymbol; + } + if (valueSymbol.flags & (SymbolFlags.Type | SymbolFlags.Namespace)) { + return valueSymbol; + } + const result = createSymbol(valueSymbol.flags | typeSymbol.flags, valueSymbol.escapedName); + Debug.assert(valueSymbol.declarations || typeSymbol.declarations); + result.declarations = deduplicate(concatenate(valueSymbol.declarations!, typeSymbol.declarations), equateValues); + result.parent = valueSymbol.parent || typeSymbol.parent; + if (valueSymbol.valueDeclaration) result.valueDeclaration = valueSymbol.valueDeclaration; + if (typeSymbol.members) result.members = new Map(typeSymbol.members); + if (valueSymbol.exports) result.exports = new Map(valueSymbol.exports); + return result; + } + + function getExportOfModule(symbol: Symbol, nameText: __String, specifier: Declaration, dontResolveAlias: boolean): Symbol | undefined { + if (symbol.flags & SymbolFlags.Module) { + const exportSymbol = getExportsOfSymbol(symbol).get(nameText); + const resolved = resolveSymbol(exportSymbol, dontResolveAlias); + const exportStarDeclaration = getSymbolLinks(symbol).typeOnlyExportStarMap?.get(nameText); + markSymbolOfAliasDeclarationIfTypeOnly(specifier, exportSymbol, resolved, /*overwriteEmpty*/ false, exportStarDeclaration, nameText); + return resolved; + } + } + + function getPropertyOfVariable(symbol: Symbol, name: __String): Symbol | undefined { + if (symbol.flags & SymbolFlags.Variable) { + const typeAnnotation = (symbol.valueDeclaration as VariableDeclaration).type; + if (typeAnnotation) { + return resolveSymbol(getPropertyOfType(getTypeFromTypeNode(typeAnnotation), name)); + } + } + } + + function getExternalModuleMember(node: ImportDeclaration | ExportDeclaration | VariableDeclaration | JSDocImportTag, specifier: ImportOrExportSpecifier | BindingElement | PropertyAccessExpression, dontResolveAlias = false): Symbol | undefined { + const moduleSpecifier = getExternalModuleRequireArgument(node) || (node as ImportDeclaration | ExportDeclaration | JSDocImportTag).moduleSpecifier!; + const moduleSymbol = resolveExternalModuleName(node, moduleSpecifier)!; // TODO: GH#18217 + const name = !isPropertyAccessExpression(specifier) && specifier.propertyName || specifier.name; + if (!isIdentifier(name) && name.kind !== SyntaxKind.StringLiteral) { + return undefined; + } + const nameText = moduleExportNameTextEscaped(name); + const suppressInteropError = nameText === InternalSymbolName.Default && allowSyntheticDefaultImports; + const targetSymbol = resolveESModuleSymbol(moduleSymbol, moduleSpecifier, /*dontResolveAlias*/ false, suppressInteropError); + if (targetSymbol) { + // Note: The empty string is a valid module export name: + // + // import { "" as foo } from "./foo"; + // export { foo as "" }; + // + if (nameText || name.kind === SyntaxKind.StringLiteral) { + if (isShorthandAmbientModuleSymbol(moduleSymbol)) { + return moduleSymbol; + } + + let symbolFromVariable: Symbol | undefined; + // First check if module was specified with "export=". If so, get the member from the resolved type + if (moduleSymbol && moduleSymbol.exports && moduleSymbol.exports.get(InternalSymbolName.ExportEquals)) { + symbolFromVariable = getPropertyOfType(getTypeOfSymbol(targetSymbol), nameText, /*skipObjectFunctionPropertyAugment*/ true); + } + else { + symbolFromVariable = getPropertyOfVariable(targetSymbol, nameText); + } + // if symbolFromVariable is export - get its final target + symbolFromVariable = resolveSymbol(symbolFromVariable, dontResolveAlias); + + let symbolFromModule = getExportOfModule(targetSymbol, nameText, specifier, dontResolveAlias); + if (symbolFromModule === undefined && nameText === InternalSymbolName.Default) { + const file = moduleSymbol.declarations?.find(isSourceFile); + if (isOnlyImportedAsDefault(moduleSpecifier) || canHaveSyntheticDefault(file, moduleSymbol, dontResolveAlias, moduleSpecifier)) { + symbolFromModule = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias) || resolveSymbol(moduleSymbol, dontResolveAlias); + } + } + + const symbol = symbolFromModule && symbolFromVariable && symbolFromModule !== symbolFromVariable ? + combineValueAndTypeSymbols(symbolFromVariable, symbolFromModule) : + symbolFromModule || symbolFromVariable; + if (!symbol) { + errorNoModuleMemberSymbol(moduleSymbol, targetSymbol, node, name); + } + return symbol; + } + } + } + + function errorNoModuleMemberSymbol(moduleSymbol: Symbol, targetSymbol: Symbol, node: Node, name: ModuleExportName) { + const moduleName = getFullyQualifiedName(moduleSymbol, node); + const declarationName = declarationNameToString(name); + const suggestion = isIdentifier(name) ? getSuggestedSymbolForNonexistentModule(name, targetSymbol) : undefined; + if (suggestion !== undefined) { + const suggestionName = symbolToString(suggestion); + const diagnostic = error(name, Diagnostics._0_has_no_exported_member_named_1_Did_you_mean_2, moduleName, declarationName, suggestionName); + if (suggestion.valueDeclaration) { + addRelatedInfo(diagnostic, createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestionName)); + } + } + else { + if (moduleSymbol.exports?.has(InternalSymbolName.Default)) { + error( + name, + Diagnostics.Module_0_has_no_exported_member_1_Did_you_mean_to_use_import_1_from_0_instead, + moduleName, + declarationName, + ); + } + else { + reportNonExportedMember(node, name, declarationName, moduleSymbol, moduleName); + } + } + } + + function reportNonExportedMember(node: Node, name: ModuleExportName, declarationName: string, moduleSymbol: Symbol, moduleName: string): void { + const localSymbol = tryCast(moduleSymbol.valueDeclaration, canHaveLocals)?.locals?.get(moduleExportNameTextEscaped(name)); + const exports = moduleSymbol.exports; + if (localSymbol) { + const exportedEqualsSymbol = exports?.get(InternalSymbolName.ExportEquals); + if (exportedEqualsSymbol) { + getSymbolIfSameReference(exportedEqualsSymbol, localSymbol) ? reportInvalidImportEqualsExportMember(node, name, declarationName, moduleName) : + error(name, Diagnostics.Module_0_has_no_exported_member_1, moduleName, declarationName); + } + else { + const exportedSymbol = exports ? find(symbolsToArray(exports), symbol => !!getSymbolIfSameReference(symbol, localSymbol)) : undefined; + const diagnostic = exportedSymbol ? error(name, Diagnostics.Module_0_declares_1_locally_but_it_is_exported_as_2, moduleName, declarationName, symbolToString(exportedSymbol)) : + error(name, Diagnostics.Module_0_declares_1_locally_but_it_is_not_exported, moduleName, declarationName); + if (localSymbol.declarations) { + addRelatedInfo(diagnostic, ...map(localSymbol.declarations, (decl, index) => createDiagnosticForNode(decl, index === 0 ? Diagnostics._0_is_declared_here : Diagnostics.and_here, declarationName))); + } + } + } + else { + error(name, Diagnostics.Module_0_has_no_exported_member_1, moduleName, declarationName); + } + } + + function reportInvalidImportEqualsExportMember(node: Node, name: ModuleExportName, declarationName: string, moduleName: string) { + if (moduleKind >= ModuleKind.ES2015) { + const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_a_default_import : + Diagnostics._0_can_only_be_imported_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; + error(name, message, declarationName); + } + else { + if (isInJSFile(node)) { + const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_a_require_call_or_by_using_a_default_import : + Diagnostics._0_can_only_be_imported_by_using_a_require_call_or_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; + error(name, message, declarationName); + } + else { + const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_import_1_require_2_or_a_default_import : + Diagnostics._0_can_only_be_imported_by_using_import_1_require_2_or_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; + error(name, message, declarationName, declarationName, moduleName); + } + } + } + + function getTargetOfImportSpecifier(node: ImportSpecifier | BindingElement, dontResolveAlias: boolean): Symbol | undefined { + if (isImportSpecifier(node) && moduleExportNameIsDefault(node.propertyName || node.name)) { + const specifier = getModuleSpecifierForImportOrExport(node); + const moduleSymbol = specifier && resolveExternalModuleName(node, specifier); + if (moduleSymbol) { + return getTargetofModuleDefault(moduleSymbol, node, dontResolveAlias); + } + } + const root = isBindingElement(node) ? getRootDeclaration(node) as VariableDeclaration : node.parent.parent.parent; + const commonJSPropertyAccess = getCommonJSPropertyAccess(root); + const resolved = getExternalModuleMember(root, commonJSPropertyAccess || node, dontResolveAlias); + const name = node.propertyName || node.name; + if (commonJSPropertyAccess && resolved && isIdentifier(name)) { + return resolveSymbol(getPropertyOfType(getTypeOfSymbol(resolved), name.escapedText), dontResolveAlias); + } + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getCommonJSPropertyAccess(node: Node) { + if (isVariableDeclaration(node) && node.initializer && isPropertyAccessExpression(node.initializer)) { + return node.initializer; + } + } + + function getTargetOfNamespaceExportDeclaration(node: NamespaceExportDeclaration, dontResolveAlias: boolean): Symbol | undefined { + if (canHaveSymbol(node.parent)) { + const resolved = resolveExternalModuleSymbol(node.parent.symbol, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + } + + function getTargetOfExportSpecifier(node: ExportSpecifier, meaning: SymbolFlags, dontResolveAlias?: boolean) { + const name = node.propertyName || node.name; + if (moduleExportNameIsDefault(name)) { + const specifier = getModuleSpecifierForImportOrExport(node); + const moduleSymbol = specifier && resolveExternalModuleName(node, specifier); + if (moduleSymbol) { + return getTargetofModuleDefault(moduleSymbol, node, !!dontResolveAlias); + } + } + const resolved = node.parent.parent.moduleSpecifier ? + getExternalModuleMember(node.parent.parent, node, dontResolveAlias) : + name.kind === SyntaxKind.StringLiteral ? undefined : // Skip for invalid syntax like this: export { "x" } + resolveEntityName(name, meaning, /*ignoreErrors*/ false, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getTargetOfExportAssignment(node: ExportAssignment | BinaryExpression, dontResolveAlias: boolean): Symbol | undefined { + const expression = isExportAssignment(node) ? node.expression : node.right; + const resolved = getTargetOfAliasLikeExpression(expression, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getTargetOfAliasLikeExpression(expression: Expression, dontResolveAlias: boolean) { + if (isClassExpression(expression)) { + return checkExpressionCached(expression).symbol; + } + if (!isEntityName(expression) && !isEntityNameExpression(expression)) { + return undefined; + } + const aliasLike = resolveEntityName(expression, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ true, dontResolveAlias); + if (aliasLike) { + return aliasLike; + } + checkExpressionCached(expression); + return getNodeLinks(expression).resolvedSymbol; + } + + function getTargetOfAccessExpression(node: AccessExpression, dontRecursivelyResolve: boolean): Symbol | undefined { + if (!(isBinaryExpression(node.parent) && node.parent.left === node && node.parent.operatorToken.kind === SyntaxKind.EqualsToken)) { + return undefined; + } + + return getTargetOfAliasLikeExpression(node.parent.right, dontRecursivelyResolve); + } + + function getTargetOfAliasDeclaration(node: Declaration, dontRecursivelyResolve = false): Symbol | undefined { + switch (node.kind) { + case SyntaxKind.ImportEqualsDeclaration: + case SyntaxKind.VariableDeclaration: + return getTargetOfImportEqualsDeclaration(node as ImportEqualsDeclaration | VariableDeclaration, dontRecursivelyResolve); + case SyntaxKind.ImportClause: + return getTargetOfImportClause(node as ImportClause, dontRecursivelyResolve); + case SyntaxKind.NamespaceImport: + return getTargetOfNamespaceImport(node as NamespaceImport, dontRecursivelyResolve); + case SyntaxKind.NamespaceExport: + return getTargetOfNamespaceExport(node as NamespaceExport, dontRecursivelyResolve); + case SyntaxKind.ImportSpecifier: + case SyntaxKind.BindingElement: + return getTargetOfImportSpecifier(node as ImportSpecifier | BindingElement, dontRecursivelyResolve); + case SyntaxKind.ExportSpecifier: + return getTargetOfExportSpecifier(node as ExportSpecifier, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, dontRecursivelyResolve); + case SyntaxKind.ExportAssignment: + case SyntaxKind.BinaryExpression: + return getTargetOfExportAssignment(node as ExportAssignment | BinaryExpression, dontRecursivelyResolve); + case SyntaxKind.NamespaceExportDeclaration: + return getTargetOfNamespaceExportDeclaration(node as NamespaceExportDeclaration, dontRecursivelyResolve); + case SyntaxKind.ShorthandPropertyAssignment: + return resolveEntityName((node as ShorthandPropertyAssignment).name, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ true, dontRecursivelyResolve); + case SyntaxKind.PropertyAssignment: + return getTargetOfAliasLikeExpression((node as PropertyAssignment).initializer, dontRecursivelyResolve); + case SyntaxKind.ElementAccessExpression: + case SyntaxKind.PropertyAccessExpression: + return getTargetOfAccessExpression(node as AccessExpression, dontRecursivelyResolve); + default: + return Debug.fail(); + } + } + + /** + * Indicates that a symbol is an alias that does not merge with a local declaration. + * OR Is a JSContainer which may merge an alias with a local declaration + */ + function isNonLocalAlias(symbol: Symbol | undefined, excludes = SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace): symbol is Symbol { + if (!symbol) return false; + return (symbol.flags & (SymbolFlags.Alias | excludes)) === SymbolFlags.Alias || !!(symbol.flags & SymbolFlags.Alias && symbol.flags & SymbolFlags.Assignment); + } + + function resolveSymbol(symbol: Symbol, dontResolveAlias?: boolean): Symbol; + function resolveSymbol(symbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined; + function resolveSymbol(symbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined { + return !dontResolveAlias && isNonLocalAlias(symbol) ? resolveAlias(symbol) : symbol; + } + + function resolveAlias(symbol: Symbol): Symbol { + Debug.assert((symbol.flags & SymbolFlags.Alias) !== 0, "Should only get Alias here."); + const links = getSymbolLinks(symbol); + if (!links.aliasTarget) { + links.aliasTarget = resolvingSymbol; + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + const target = getTargetOfAliasDeclaration(node); + if (links.aliasTarget === resolvingSymbol) { + links.aliasTarget = target || unknownSymbol; + } + else { + error(node, Diagnostics.Circular_definition_of_import_alias_0, symbolToString(symbol)); + } + } + else if (links.aliasTarget === resolvingSymbol) { + links.aliasTarget = unknownSymbol; + } + return links.aliasTarget; + } + + function tryResolveAlias(symbol: Symbol): Symbol | undefined { + const links = getSymbolLinks(symbol); + if (links.aliasTarget !== resolvingSymbol) { + return resolveAlias(symbol); + } + + return undefined; + } + + /** + * Gets combined flags of a `symbol` and all alias targets it resolves to. `resolveAlias` + * is typically recursive over chains of aliases, but stops mid-chain if an alias is merged + * with another exported symbol, e.g. + * ```ts + * // a.ts + * export const a = 0; + * // b.ts + * export { a } from "./a"; + * export type a = number; + * // c.ts + * import { a } from "./b"; + * ``` + * Calling `resolveAlias` on the `a` in c.ts would stop at the merged symbol exported + * from b.ts, even though there is still more alias to resolve. Consequently, if we were + * trying to determine if the `a` in c.ts has a value meaning, looking at the flags on + * the local symbol and on the symbol returned by `resolveAlias` is not enough. + * @returns SymbolFlags.All if `symbol` is an alias that ultimately resolves to `unknown`; + * combined flags of all alias targets otherwise. + */ + function getSymbolFlags(symbol: Symbol, excludeTypeOnlyMeanings?: boolean, excludeLocalMeanings?: boolean): SymbolFlags { + const typeOnlyDeclaration = excludeTypeOnlyMeanings && getTypeOnlyAliasDeclaration(symbol); + const typeOnlyDeclarationIsExportStar = typeOnlyDeclaration && isExportDeclaration(typeOnlyDeclaration); + const typeOnlyResolution = typeOnlyDeclaration && ( + typeOnlyDeclarationIsExportStar + ? resolveExternalModuleName(typeOnlyDeclaration.moduleSpecifier, typeOnlyDeclaration.moduleSpecifier, /*ignoreErrors*/ true) + : resolveAlias(typeOnlyDeclaration.symbol) + ); + const typeOnlyExportStarTargets = typeOnlyDeclarationIsExportStar && typeOnlyResolution ? getExportsOfModule(typeOnlyResolution) : undefined; + let flags = excludeLocalMeanings ? SymbolFlags.None : symbol.flags; + let seenSymbols; + while (symbol.flags & SymbolFlags.Alias) { + const target = getExportSymbolOfValueSymbolIfExported(resolveAlias(symbol)); + if ( + !typeOnlyDeclarationIsExportStar && target === typeOnlyResolution || + typeOnlyExportStarTargets?.get(target.escapedName) === target + ) { + break; + } + if (target === unknownSymbol) { + return SymbolFlags.All; + } + + // Optimizations - try to avoid creating or adding to + // `seenSymbols` if possible + if (target === symbol || seenSymbols?.has(target)) { + break; + } + if (target.flags & SymbolFlags.Alias) { + if (seenSymbols) { + seenSymbols.add(target); + } + else { + seenSymbols = new Set([symbol, target]); + } + } + flags |= target.flags; + symbol = target; + } + return flags; + } + + /** + * Marks a symbol as type-only if its declaration is syntactically type-only. + * If it is not itself marked type-only, but resolves to a type-only alias + * somewhere in its resolution chain, save a reference to the type-only alias declaration + * so the alias _not_ marked type-only can be identified as _transitively_ type-only. + * + * This function is called on each alias declaration that could be type-only or resolve to + * another type-only alias during `resolveAlias`, so that later, when an alias is used in a + * JS-emitting expression, we can quickly determine if that symbol is effectively type-only + * and issue an error if so. + * + * @param aliasDeclaration The alias declaration not marked as type-only + * @param immediateTarget The symbol to which the alias declaration immediately resolves + * @param finalTarget The symbol to which the alias declaration ultimately resolves + * @param overwriteEmpty Checks `resolvesToSymbol` for type-only declarations even if `aliasDeclaration` + * has already been marked as not resolving to a type-only alias. Used when recursively resolving qualified + * names of import aliases, e.g. `import C = a.b.C`. If namespace `a` is not found to be type-only, the + * import declaration will initially be marked as not resolving to a type-only symbol. But, namespace `b` + * must still be checked for a type-only marker, overwriting the previous negative result if found. + */ + function markSymbolOfAliasDeclarationIfTypeOnly( + aliasDeclaration: Declaration | undefined, + immediateTarget: Symbol | undefined, + finalTarget: Symbol | undefined, + overwriteEmpty: boolean, + exportStarDeclaration?: ExportDeclaration & { readonly isTypeOnly: true; readonly moduleSpecifier: Expression; }, + exportStarName?: __String, + ): boolean { + if (!aliasDeclaration || isPropertyAccessExpression(aliasDeclaration)) return false; + + // If the declaration itself is type-only, mark it and return. + // No need to check what it resolves to. + const sourceSymbol = getSymbolOfDeclaration(aliasDeclaration); + if (isTypeOnlyImportOrExportDeclaration(aliasDeclaration)) { + const links = getSymbolLinks(sourceSymbol); + links.typeOnlyDeclaration = aliasDeclaration; + return true; + } + if (exportStarDeclaration) { + const links = getSymbolLinks(sourceSymbol); + links.typeOnlyDeclaration = exportStarDeclaration; + if (sourceSymbol.escapedName !== exportStarName) { + links.typeOnlyExportStarName = exportStarName; + } + return true; + } + + const links = getSymbolLinks(sourceSymbol); + return markSymbolOfAliasDeclarationIfTypeOnlyWorker(links, immediateTarget, overwriteEmpty) + || markSymbolOfAliasDeclarationIfTypeOnlyWorker(links, finalTarget, overwriteEmpty); + } + + function markSymbolOfAliasDeclarationIfTypeOnlyWorker(aliasDeclarationLinks: SymbolLinks, target: Symbol | undefined, overwriteEmpty: boolean): boolean { + if (target && (aliasDeclarationLinks.typeOnlyDeclaration === undefined || overwriteEmpty && aliasDeclarationLinks.typeOnlyDeclaration === false)) { + const exportSymbol = target.exports?.get(InternalSymbolName.ExportEquals) ?? target; + const typeOnly = exportSymbol.declarations && find(exportSymbol.declarations, isTypeOnlyImportOrExportDeclaration); + aliasDeclarationLinks.typeOnlyDeclaration = typeOnly ?? getSymbolLinks(exportSymbol).typeOnlyDeclaration ?? false; + } + return !!aliasDeclarationLinks.typeOnlyDeclaration; + } + + /** Indicates that a symbol directly or indirectly resolves to a type-only import or export. */ + function getTypeOnlyAliasDeclaration(symbol: Symbol, include?: SymbolFlags): TypeOnlyAliasDeclaration | undefined { + if (!(symbol.flags & SymbolFlags.Alias)) { + return undefined; + } + const links = getSymbolLinks(symbol); + if (links.typeOnlyDeclaration === undefined) { + // We need to set a WIP value here to prevent reentrancy during `getImmediateAliasedSymbol` which, paradoxically, can depend on this + links.typeOnlyDeclaration = false; + const resolved = resolveSymbol(symbol); // do this before the `resolveImmediate` below, as it uses a different circularity cache and we might hide a circularity error if we blindly get the immediate alias first + // While usually the alias will have been marked during the pass by the full typecheck, we may still need to calculate the alias declaration now + markSymbolOfAliasDeclarationIfTypeOnly(symbol.declarations?.[0], getDeclarationOfAliasSymbol(symbol) && getImmediateAliasedSymbol(symbol), resolved, /*overwriteEmpty*/ true); + } + if (include === undefined) { + return links.typeOnlyDeclaration || undefined; + } + if (links.typeOnlyDeclaration) { + const resolved = links.typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration + ? resolveSymbol(getExportsOfModule(links.typeOnlyDeclaration.symbol.parent!).get(links.typeOnlyExportStarName || symbol.escapedName))! + : resolveAlias(links.typeOnlyDeclaration.symbol); + return getSymbolFlags(resolved) & include ? links.typeOnlyDeclaration : undefined; + } + return undefined; + } + + // This function is only for imports with entity names + function getSymbolOfPartOfRightHandSideOfImportEquals(entityName: EntityName, dontResolveAlias?: boolean): Symbol | undefined { + // There are three things we might try to look for. In the following examples, + // the search term is enclosed in |...|: + // + // import a = |b|; // Namespace + // import a = |b.c|; // Value, type, namespace + // import a = |b.c|.d; // Namespace + if (entityName.kind === SyntaxKind.Identifier && isRightSideOfQualifiedNameOrPropertyAccess(entityName)) { + entityName = entityName.parent as QualifiedName; + } + // Check for case 1 and 3 in the above example + if (entityName.kind === SyntaxKind.Identifier || entityName.parent.kind === SyntaxKind.QualifiedName) { + return resolveEntityName(entityName, SymbolFlags.Namespace, /*ignoreErrors*/ false, dontResolveAlias); + } + else { + // Case 2 in above example + // entityName.kind could be a QualifiedName or a Missing identifier + Debug.assert(entityName.parent.kind === SyntaxKind.ImportEqualsDeclaration); + return resolveEntityName(entityName, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ false, dontResolveAlias); + } + } + + function getFullyQualifiedName(symbol: Symbol, containingLocation?: Node): string { + return symbol.parent ? getFullyQualifiedName(symbol.parent, containingLocation) + "." + symbolToString(symbol) : symbolToString(symbol, containingLocation, /*meaning*/ undefined, SymbolFormatFlags.DoNotIncludeSymbolChain | SymbolFormatFlags.AllowAnyNodeKind); + } + + function getContainingQualifiedNameNode(node: QualifiedName) { + while (isQualifiedName(node.parent)) { + node = node.parent; + } + return node; + } + + function tryGetQualifiedNameAsValue(node: QualifiedName) { + let left: Identifier | QualifiedName = getFirstIdentifier(node); + let symbol = resolveName(left, left, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (!symbol) { + return undefined; + } + while (isQualifiedName(left.parent)) { + const type = getTypeOfSymbol(symbol); + symbol = getPropertyOfType(type, left.parent.right.escapedText); + if (!symbol) { + return undefined; + } + left = left.parent; + } + return symbol; + } + + /** + * Resolves a qualified name and any involved aliases. + */ + function resolveEntityName(name: EntityNameOrEntityNameExpression, meaning: SymbolFlags, ignoreErrors?: boolean, dontResolveAlias?: boolean, location?: Node): Symbol | undefined { + if (nodeIsMissing(name)) { + return undefined; + } + + const namespaceMeaning = SymbolFlags.Namespace | (isInJSFile(name) ? meaning & SymbolFlags.Value : 0); + let symbol: Symbol | undefined; + if (name.kind === SyntaxKind.Identifier) { + const message = meaning === namespaceMeaning || nodeIsSynthesized(name) ? Diagnostics.Cannot_find_namespace_0 : getCannotFindNameDiagnosticForName(getFirstIdentifier(name)); + const symbolFromJSPrototype = isInJSFile(name) && !nodeIsSynthesized(name) ? resolveEntityNameFromAssignmentDeclaration(name, meaning) : undefined; + symbol = getMergedSymbol(resolveName(location || name, name, meaning, ignoreErrors || symbolFromJSPrototype ? undefined : message, /*isUse*/ true, /*excludeGlobals*/ false)); + if (!symbol) { + return getMergedSymbol(symbolFromJSPrototype); + } + } + else if (name.kind === SyntaxKind.QualifiedName || name.kind === SyntaxKind.PropertyAccessExpression) { + const left = name.kind === SyntaxKind.QualifiedName ? name.left : name.expression; + const right = name.kind === SyntaxKind.QualifiedName ? name.right : name.name; + let namespace = resolveEntityName(left, namespaceMeaning, ignoreErrors, /*dontResolveAlias*/ false, location); + if (!namespace || nodeIsMissing(right)) { + return undefined; + } + else if (namespace === unknownSymbol) { + return namespace; + } + if ( + namespace.valueDeclaration && + isInJSFile(namespace.valueDeclaration) && + getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Bundler && + isVariableDeclaration(namespace.valueDeclaration) && + namespace.valueDeclaration.initializer && + isCommonJsRequire(namespace.valueDeclaration.initializer) + ) { + const moduleName = (namespace.valueDeclaration.initializer as CallExpression).arguments[0] as StringLiteral; + const moduleSym = resolveExternalModuleName(moduleName, moduleName); + if (moduleSym) { + const resolvedModuleSymbol = resolveExternalModuleSymbol(moduleSym); + if (resolvedModuleSymbol) { + namespace = resolvedModuleSymbol; + } + } + } + symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(namespace), right.escapedText, meaning)); + if (!symbol && (namespace.flags & SymbolFlags.Alias)) { + // `namespace` can be resolved further if there was a symbol merge with a re-export + symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(resolveAlias(namespace)), right.escapedText, meaning)); + } + if (!symbol) { + if (!ignoreErrors) { + const namespaceName = getFullyQualifiedName(namespace); + const declarationName = declarationNameToString(right); + const suggestionForNonexistentModule = getSuggestedSymbolForNonexistentModule(right, namespace); + if (suggestionForNonexistentModule) { + error(right, Diagnostics._0_has_no_exported_member_named_1_Did_you_mean_2, namespaceName, declarationName, symbolToString(suggestionForNonexistentModule)); + return undefined; + } + + const containingQualifiedName = isQualifiedName(name) && getContainingQualifiedNameNode(name); + const canSuggestTypeof = globalObjectType // <-- can't pull on types if global types aren't initialized yet + && (meaning & SymbolFlags.Type) + && containingQualifiedName + && !isTypeOfExpression(containingQualifiedName.parent) + && tryGetQualifiedNameAsValue(containingQualifiedName); + if (canSuggestTypeof) { + error( + containingQualifiedName, + Diagnostics._0_refers_to_a_value_but_is_being_used_as_a_type_here_Did_you_mean_typeof_0, + entityNameToString(containingQualifiedName), + ); + return undefined; + } + + if (meaning & SymbolFlags.Namespace && isQualifiedName(name.parent)) { + const exportedTypeSymbol = getMergedSymbol(getSymbol(getExportsOfSymbol(namespace), right.escapedText, SymbolFlags.Type)); + if (exportedTypeSymbol) { + error( + name.parent.right, + Diagnostics.Cannot_access_0_1_because_0_is_a_type_but_not_a_namespace_Did_you_mean_to_retrieve_the_type_of_the_property_1_in_0_with_0_1, + symbolToString(exportedTypeSymbol), + unescapeLeadingUnderscores(name.parent.right.escapedText), + ); + return undefined; + } + } + + error(right, Diagnostics.Namespace_0_has_no_exported_member_1, namespaceName, declarationName); + } + return undefined; + } + } + else { + Debug.assertNever(name, "Unknown entity name kind."); + } + if (!nodeIsSynthesized(name) && isEntityName(name) && (symbol.flags & SymbolFlags.Alias || name.parent.kind === SyntaxKind.ExportAssignment)) { + markSymbolOfAliasDeclarationIfTypeOnly(getAliasDeclarationFromName(name), symbol, /*finalTarget*/ undefined, /*overwriteEmpty*/ true); + } + return (symbol.flags & meaning) || dontResolveAlias ? symbol : resolveAlias(symbol); + } + + /** + * 1. For prototype-property methods like `A.prototype.m = function () ...`, try to resolve names in the scope of `A` too. + * Note that prototype-property assignment to locations outside the current file (eg globals) doesn't work, so + * name resolution won't work either. + * 2. For property assignments like `{ x: function f () { } }`, try to resolve names in the scope of `f` too. + */ + function resolveEntityNameFromAssignmentDeclaration(name: Identifier, meaning: SymbolFlags) { + if (isJSDocTypeReference(name.parent)) { + const secondaryLocation = getAssignmentDeclarationLocation(name.parent); + if (secondaryLocation) { + return resolveName(secondaryLocation, name, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + } + } + } + + function getAssignmentDeclarationLocation(node: TypeReferenceNode): Node | undefined { + const typeAlias = findAncestor(node, node => !(isJSDocNode(node) || node.flags & NodeFlags.JSDoc) ? "quit" : isJSDocTypeAlias(node)); + if (typeAlias) { + return; + } + const host = getJSDocHost(node); + if (host && isExpressionStatement(host) && isPrototypePropertyAssignment(host.expression)) { + // /** @param {K} p */ X.prototype.m = function () { } <-- look for K on X's declaration + const symbol = getSymbolOfDeclaration(host.expression.left); + if (symbol) { + return getDeclarationOfJSPrototypeContainer(symbol); + } + } + if (host && isFunctionExpression(host) && isPrototypePropertyAssignment(host.parent) && isExpressionStatement(host.parent.parent)) { + // X.prototype.m = /** @param {K} p */ function () { } <-- look for K on X's declaration + const symbol = getSymbolOfDeclaration(host.parent.left); + if (symbol) { + return getDeclarationOfJSPrototypeContainer(symbol); + } + } + if ( + host && (isObjectLiteralMethod(host) || isPropertyAssignment(host)) && + isBinaryExpression(host.parent.parent) && + getAssignmentDeclarationKind(host.parent.parent) === AssignmentDeclarationKind.Prototype + ) { + // X.prototype = { /** @param {K} p */m() { } } <-- look for K on X's declaration + const symbol = getSymbolOfDeclaration(host.parent.parent.left as BindableStaticNameExpression); + if (symbol) { + return getDeclarationOfJSPrototypeContainer(symbol); + } + } + const sig = getEffectiveJSDocHost(node); + if (sig && isFunctionLike(sig)) { + const symbol = getSymbolOfDeclaration(sig); + return symbol && symbol.valueDeclaration; + } + } + + function getDeclarationOfJSPrototypeContainer(symbol: Symbol) { + const decl = symbol.parent!.valueDeclaration; + if (!decl) { + return undefined; + } + const initializer = isAssignmentDeclaration(decl) ? getAssignedExpandoInitializer(decl) : + hasOnlyExpressionInitializer(decl) ? getDeclaredExpandoInitializer(decl) : + undefined; + return initializer || decl; + } + + /** + * Get the real symbol of a declaration with an expando initializer. + * + * Normally, declarations have an associated symbol, but when a declaration has an expando + * initializer, the expando's symbol is the one that has all the members merged into it. + */ + function getExpandoSymbol(symbol: Symbol): Symbol | undefined { + const decl = symbol.valueDeclaration; + if (!decl || !isInJSFile(decl) || symbol.flags & SymbolFlags.TypeAlias || getExpandoInitializer(decl, /*isPrototypeAssignment*/ false)) { + return undefined; + } + const init = isVariableDeclaration(decl) ? getDeclaredExpandoInitializer(decl) : getAssignedExpandoInitializer(decl); + if (init) { + const initSymbol = getSymbolOfNode(init); + if (initSymbol) { + return mergeJSSymbols(initSymbol, symbol); + } + } + } + + function resolveExternalModuleName(location: Node, moduleReferenceExpression: Expression, ignoreErrors?: boolean): Symbol | undefined { + const isClassic = getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic; + const errorMessage = isClassic ? + Diagnostics.Cannot_find_module_0_Did_you_mean_to_set_the_moduleResolution_option_to_nodenext_or_to_add_aliases_to_the_paths_option + : Diagnostics.Cannot_find_module_0_or_its_corresponding_type_declarations; + return resolveExternalModuleNameWorker(location, moduleReferenceExpression, ignoreErrors ? undefined : errorMessage); + } + + function resolveExternalModuleNameWorker(location: Node, moduleReferenceExpression: Expression, moduleNotFoundError: DiagnosticMessage | undefined, isForAugmentation = false): Symbol | undefined { + return isStringLiteralLike(moduleReferenceExpression) + ? resolveExternalModule(location, moduleReferenceExpression.text, moduleNotFoundError, moduleReferenceExpression, isForAugmentation) + : undefined; + } + + function resolveExternalModule(location: Node, moduleReference: string, moduleNotFoundError: DiagnosticMessage | undefined, errorNode: Node, isForAugmentation = false): Symbol | undefined { + if (startsWith(moduleReference, "@types/")) { + const diag = Diagnostics.Cannot_import_type_declaration_files_Consider_importing_0_instead_of_1; + const withoutAtTypePrefix = removePrefix(moduleReference, "@types/"); + error(errorNode, diag, withoutAtTypePrefix, moduleReference); + } + + const ambientModule = tryFindAmbientModule(moduleReference, /*withAugmentations*/ true); + if (ambientModule) { + return ambientModule; + } + const currentSourceFile = getSourceFileOfNode(location); + const contextSpecifier = isStringLiteralLike(location) + ? location + : (isModuleDeclaration(location) ? location : location.parent && isModuleDeclaration(location.parent) && location.parent.name === location ? location.parent : undefined)?.name || + (isLiteralImportTypeNode(location) ? location : undefined)?.argument.literal || + (isInJSFile(location) && isJSDocImportTag(location) ? location.moduleSpecifier : undefined) || + (isVariableDeclaration(location) && location.initializer && isRequireCall(location.initializer, /*requireStringLiteralLikeArgument*/ true) ? location.initializer.arguments[0] : undefined) || + findAncestor(location, isImportCall)?.arguments[0] || + findAncestor(location, isImportDeclaration)?.moduleSpecifier || + findAncestor(location, isExternalModuleImportEqualsDeclaration)?.moduleReference.expression || + findAncestor(location, isExportDeclaration)?.moduleSpecifier; + const mode = contextSpecifier && isStringLiteralLike(contextSpecifier) ? host.getModeForUsageLocation(currentSourceFile, contextSpecifier) : currentSourceFile.impliedNodeFormat; + const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions); + const resolvedModule = host.getResolvedModule(currentSourceFile, moduleReference, mode)?.resolvedModule; + const resolutionDiagnostic = resolvedModule && getResolutionDiagnostic(compilerOptions, resolvedModule, currentSourceFile); + const sourceFile = resolvedModule + && (!resolutionDiagnostic || resolutionDiagnostic === Diagnostics.Module_0_was_resolved_to_1_but_jsx_is_not_set) + && host.getSourceFile(resolvedModule.resolvedFileName); + if (sourceFile) { + // If there's a resolutionDiagnostic we need to report it even if a sourceFile is found. + if (resolutionDiagnostic) { + error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName); + } + + if (resolvedModule.resolvedUsingTsExtension && isDeclarationFileName(moduleReference)) { + const importOrExport = findAncestor(location, isImportDeclaration)?.importClause || + findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)); + if (importOrExport && !importOrExport.isTypeOnly || findAncestor(location, isImportCall)) { + error( + errorNode, + Diagnostics.A_declaration_file_cannot_be_imported_without_import_type_Did_you_mean_to_import_an_implementation_file_0_instead, + getSuggestedImportSource(Debug.checkDefined(tryExtractTSExtension(moduleReference))), + ); + } + } + else if (resolvedModule.resolvedUsingTsExtension && !shouldAllowImportingTsExtension(compilerOptions, currentSourceFile.fileName)) { + const importOrExport = findAncestor(location, isImportDeclaration)?.importClause || + findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)); + if (!(importOrExport?.isTypeOnly || findAncestor(location, isImportTypeNode))) { + const tsExtension = Debug.checkDefined(tryExtractTSExtension(moduleReference)); + error(errorNode, Diagnostics.An_import_path_can_only_end_with_a_0_extension_when_allowImportingTsExtensions_is_enabled, tsExtension); + } + } + + if (sourceFile.symbol) { + if (resolvedModule.isExternalLibraryImport && !resolutionExtensionIsTSOrJson(resolvedModule.extension)) { + errorOnImplicitAnyModule(/*isError*/ false, errorNode, currentSourceFile, mode, resolvedModule, moduleReference); + } + if (moduleResolutionKind === ModuleResolutionKind.Node16 || moduleResolutionKind === ModuleResolutionKind.NodeNext) { + const isSyncImport = (currentSourceFile.impliedNodeFormat === ModuleKind.CommonJS && !findAncestor(location, isImportCall)) || !!findAncestor(location, isImportEqualsDeclaration); + const overrideHost = findAncestor(location, l => isImportTypeNode(l) || isExportDeclaration(l) || isImportDeclaration(l)) as ImportTypeNode | ImportDeclaration | ExportDeclaration | undefined; + // An override clause will take effect for type-only imports and import types, and allows importing the types across formats, regardless of + // normal mode restrictions + if (isSyncImport && sourceFile.impliedNodeFormat === ModuleKind.ESNext && !hasResolutionModeOverride(overrideHost)) { + if (findAncestor(location, isImportEqualsDeclaration)) { + // ImportEquals in a ESM file resolving to another ESM file + error(errorNode, Diagnostics.Module_0_cannot_be_imported_using_this_construct_The_specifier_only_resolves_to_an_ES_module_which_cannot_be_imported_with_require_Use_an_ECMAScript_import_instead, moduleReference); + } + else { + // CJS file resolving to an ESM file + let diagnosticDetails; + const ext = tryGetExtensionFromPath(currentSourceFile.fileName); + if (ext === Extension.Ts || ext === Extension.Js || ext === Extension.Tsx || ext === Extension.Jsx) { + const scope = currentSourceFile.packageJsonScope; + const targetExt = ext === Extension.Ts ? Extension.Mts : ext === Extension.Js ? Extension.Mjs : undefined; + if (scope && !scope.contents.packageJsonContent.type) { + if (targetExt) { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_add_the_field_type_Colon_module_to_1, + targetExt, + combinePaths(scope.packageDirectory, "package.json"), + ); + } + else { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_add_the_field_type_Colon_module_to_0, + combinePaths(scope.packageDirectory, "package.json"), + ); + } + } + else { + if (targetExt) { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_create_a_local_package_json_file_with_type_Colon_module, + targetExt, + ); + } + else { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_create_a_local_package_json_file_with_type_Colon_module, + ); + } + } + } + diagnostics.add(createDiagnosticForNodeFromMessageChain( + getSourceFileOfNode(errorNode), + errorNode, + chainDiagnosticMessages( + diagnosticDetails, + Diagnostics.The_current_file_is_a_CommonJS_module_whose_imports_will_produce_require_calls_however_the_referenced_file_is_an_ECMAScript_module_and_cannot_be_imported_with_require_Consider_writing_a_dynamic_import_0_call_instead, + moduleReference, + ), + )); + } + } + } + // merged symbol is module declaration symbol combined with all augmentations + return getMergedSymbol(sourceFile.symbol); + } + if (moduleNotFoundError) { + // report errors only if it was requested + error(errorNode, Diagnostics.File_0_is_not_a_module, sourceFile.fileName); + } + return undefined; + } + + if (patternAmbientModules) { + const pattern = findBestPatternMatch(patternAmbientModules, _ => _.pattern, moduleReference); + if (pattern) { + // If the module reference matched a pattern ambient module ('*.foo') but there's also a + // module augmentation by the specific name requested ('a.foo'), we store the merged symbol + // by the augmentation name ('a.foo'), because asking for *.foo should not give you exports + // from a.foo. + const augmentation = patternAmbientModuleAugmentations && patternAmbientModuleAugmentations.get(moduleReference); + if (augmentation) { + return getMergedSymbol(augmentation); + } + return getMergedSymbol(pattern.symbol); + } + } + + // May be an untyped module. If so, ignore resolutionDiagnostic. + if (resolvedModule && !resolutionExtensionIsTSOrJson(resolvedModule.extension) && resolutionDiagnostic === undefined || resolutionDiagnostic === Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type) { + if (isForAugmentation) { + const diag = Diagnostics.Invalid_module_name_in_augmentation_Module_0_resolves_to_an_untyped_module_at_1_which_cannot_be_augmented; + error(errorNode, diag, moduleReference, resolvedModule!.resolvedFileName); + } + else { + errorOnImplicitAnyModule(/*isError*/ noImplicitAny && !!moduleNotFoundError, errorNode, currentSourceFile, mode, resolvedModule!, moduleReference); + } + // Failed imports and untyped modules are both treated in an untyped manner; only difference is whether we give a diagnostic first. + return undefined; + } + + if (moduleNotFoundError) { + // See if this was possibly a projectReference redirect + if (resolvedModule) { + const redirect = host.getProjectReferenceRedirect(resolvedModule.resolvedFileName); + if (redirect) { + error(errorNode, Diagnostics.Output_file_0_has_not_been_built_from_source_file_1, redirect, resolvedModule.resolvedFileName); + return undefined; + } + } + + if (resolutionDiagnostic) { + error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName); + } + else { + const isExtensionlessRelativePathImport = pathIsRelative(moduleReference) && !hasExtension(moduleReference); + const resolutionIsNode16OrNext = moduleResolutionKind === ModuleResolutionKind.Node16 || + moduleResolutionKind === ModuleResolutionKind.NodeNext; + if ( + !getResolveJsonModule(compilerOptions) && + fileExtensionIs(moduleReference, Extension.Json) && + moduleResolutionKind !== ModuleResolutionKind.Classic && + hasJsonModuleEmitEnabled(compilerOptions) + ) { + error(errorNode, Diagnostics.Cannot_find_module_0_Consider_using_resolveJsonModule_to_import_module_with_json_extension, moduleReference); + } + else if (mode === ModuleKind.ESNext && resolutionIsNode16OrNext && isExtensionlessRelativePathImport) { + const absoluteRef = getNormalizedAbsolutePath(moduleReference, getDirectoryPath(currentSourceFile.path)); + const suggestedExt = suggestedExtensions.find(([actualExt, _importExt]) => host.fileExists(absoluteRef + actualExt))?.[1]; + if (suggestedExt) { + error(errorNode, Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_ECMAScript_imports_when_moduleResolution_is_node16_or_nodenext_Did_you_mean_0, moduleReference + suggestedExt); + } + else { + error(errorNode, Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_ECMAScript_imports_when_moduleResolution_is_node16_or_nodenext_Consider_adding_an_extension_to_the_import_path); + } + } + else { + if (host.getResolvedModule(currentSourceFile, moduleReference, mode)?.alternateResult) { + const errorInfo = createModuleNotFoundChain(currentSourceFile, host, moduleReference, mode, moduleReference); + errorOrSuggestion(/*isError*/ true, errorNode, chainDiagnosticMessages(errorInfo, moduleNotFoundError, moduleReference)); + } + else { + error(errorNode, moduleNotFoundError, moduleReference); + } + } + } + } + return undefined; + + function getSuggestedImportSource(tsExtension: string) { + const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension); + /** + * Direct users to import source with .js extension if outputting an ES module. + * @see https://github.com/microsoft/TypeScript/issues/42151 + */ + if (emitModuleKindIsNonNodeESM(moduleKind) || mode === ModuleKind.ESNext) { + const preferTs = isDeclarationFileName(moduleReference) && shouldAllowImportingTsExtension(compilerOptions); + const ext = tsExtension === Extension.Mts || tsExtension === Extension.Dmts ? preferTs ? ".mts" : ".mjs" : + tsExtension === Extension.Cts || tsExtension === Extension.Dmts ? preferTs ? ".cts" : ".cjs" : + preferTs ? ".ts" : ".js"; + return importSourceWithoutExtension + ext; + } + return importSourceWithoutExtension; + } + } + + function errorOnImplicitAnyModule(isError: boolean, errorNode: Node, sourceFile: SourceFile, mode: ResolutionMode, { packageId, resolvedFileName }: ResolvedModuleFull, moduleReference: string): void { + let errorInfo: DiagnosticMessageChain | undefined; + if (!isExternalModuleNameRelative(moduleReference) && packageId) { + errorInfo = createModuleNotFoundChain(sourceFile, host, moduleReference, mode, packageId.name); + } + errorOrSuggestion( + isError, + errorNode, + chainDiagnosticMessages( + errorInfo, + Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type, + moduleReference, + resolvedFileName, + ), + ); + } + + function resolveExternalModuleSymbol(moduleSymbol: Symbol, dontResolveAlias?: boolean): Symbol; + function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined; + function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined { + if (moduleSymbol?.exports) { + const exportEquals = resolveSymbol(moduleSymbol.exports.get(InternalSymbolName.ExportEquals), dontResolveAlias); + const exported = getCommonJsExportEquals(getMergedSymbol(exportEquals), getMergedSymbol(moduleSymbol)); + return getMergedSymbol(exported) || moduleSymbol; + } + return undefined; + } + + function getCommonJsExportEquals(exported: Symbol | undefined, moduleSymbol: Symbol): Symbol | undefined { + if (!exported || exported === unknownSymbol || exported === moduleSymbol || moduleSymbol.exports!.size === 1 || exported.flags & SymbolFlags.Alias) { + return exported; + } + const links = getSymbolLinks(exported); + if (links.cjsExportMerged) { + return links.cjsExportMerged; + } + const merged = exported.flags & SymbolFlags.Transient ? exported : cloneSymbol(exported); + merged.flags = merged.flags | SymbolFlags.ValueModule; + if (merged.exports === undefined) { + merged.exports = createSymbolTable(); + } + moduleSymbol.exports!.forEach((s, name) => { + if (name === InternalSymbolName.ExportEquals) return; + merged.exports!.set(name, merged.exports!.has(name) ? mergeSymbol(merged.exports!.get(name)!, s) : s); + }); + if (merged === exported) { + // We just mutated a symbol, reset any cached links we may have already set + // (Notably required to make late bound members appear) + getSymbolLinks(merged).resolvedExports = undefined; + getSymbolLinks(merged).resolvedMembers = undefined; + } + getSymbolLinks(merged).cjsExportMerged = merged; + return links.cjsExportMerged = merged; + } + + // An external module with an 'export =' declaration may be referenced as an ES6 module provided the 'export =' + // references a symbol that is at least declared as a module or a variable. The target of the 'export =' may + // combine other declarations with the module or variable (e.g. a class/module, function/module, interface/variable). + function resolveESModuleSymbol(moduleSymbol: Symbol | undefined, referencingLocation: Node, dontResolveAlias: boolean, suppressInteropError: boolean): Symbol | undefined { + const symbol = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias); + + if (!dontResolveAlias && symbol) { + if (!suppressInteropError && !(symbol.flags & (SymbolFlags.Module | SymbolFlags.Variable)) && !getDeclarationOfKind(symbol, SyntaxKind.SourceFile)) { + const compilerOptionName = moduleKind >= ModuleKind.ES2015 + ? "allowSyntheticDefaultImports" + : "esModuleInterop"; + + error(referencingLocation, Diagnostics.This_module_can_only_be_referenced_with_ECMAScript_imports_Slashexports_by_turning_on_the_0_flag_and_referencing_its_default_export, compilerOptionName); + + return symbol; + } + + const referenceParent = referencingLocation.parent; + if ( + (isImportDeclaration(referenceParent) && getNamespaceDeclarationNode(referenceParent)) || + isImportCall(referenceParent) + ) { + const reference = isImportCall(referenceParent) ? referenceParent.arguments[0] : referenceParent.moduleSpecifier; + const type = getTypeOfSymbol(symbol); + const defaultOnlyType = getTypeWithSyntheticDefaultOnly(type, symbol, moduleSymbol!, reference); + if (defaultOnlyType) { + return cloneTypeAsModuleType(symbol, defaultOnlyType, referenceParent); + } + + const targetFile = moduleSymbol?.declarations?.find(isSourceFile); + const isEsmCjsRef = targetFile && isESMFormatImportImportingCommonjsFormatFile(getUsageModeForExpression(reference), targetFile.impliedNodeFormat); + if (getESModuleInterop(compilerOptions) || isEsmCjsRef) { + let sigs = getSignaturesOfStructuredType(type, SignatureKind.Call); + if (!sigs || !sigs.length) { + sigs = getSignaturesOfStructuredType(type, SignatureKind.Construct); + } + if ( + (sigs && sigs.length) || + getPropertyOfType(type, InternalSymbolName.Default, /*skipObjectFunctionPropertyAugment*/ true) || + isEsmCjsRef + ) { + const moduleType = type.flags & TypeFlags.StructuredType + ? getTypeWithSyntheticDefaultImportType(type, symbol, moduleSymbol!, reference) + : createDefaultPropertyWrapperForModule(symbol, symbol.parent); + return cloneTypeAsModuleType(symbol, moduleType, referenceParent); + } + } + } + } + return symbol; + } + + /** + * Create a new symbol which has the module's type less the call and construct signatures + */ + function cloneTypeAsModuleType(symbol: Symbol, moduleType: Type, referenceParent: ImportDeclaration | ImportCall) { + const result = createSymbol(symbol.flags, symbol.escapedName); + result.declarations = symbol.declarations ? symbol.declarations.slice() : []; + result.parent = symbol.parent; + result.links.target = symbol; + result.links.originatingImport = referenceParent; + if (symbol.valueDeclaration) result.valueDeclaration = symbol.valueDeclaration; + if (symbol.constEnumOnlyModule) result.constEnumOnlyModule = true; + if (symbol.members) result.members = new Map(symbol.members); + if (symbol.exports) result.exports = new Map(symbol.exports); + const resolvedModuleType = resolveStructuredTypeMembers(moduleType as StructuredType); // Should already be resolved from the signature checks above + result.links.type = createAnonymousType(result, resolvedModuleType.members, emptyArray, emptyArray, resolvedModuleType.indexInfos); + return result; + } + + function hasExportAssignmentSymbol(moduleSymbol: Symbol): boolean { + return moduleSymbol.exports!.get(InternalSymbolName.ExportEquals) !== undefined; + } + + function getExportsOfModuleAsArray(moduleSymbol: Symbol): Symbol[] { + return symbolsToArray(getExportsOfModule(moduleSymbol)); + } + + function getExportsAndPropertiesOfModule(moduleSymbol: Symbol): Symbol[] { + const exports = getExportsOfModuleAsArray(moduleSymbol); + const exportEquals = resolveExternalModuleSymbol(moduleSymbol); + if (exportEquals !== moduleSymbol) { + const type = getTypeOfSymbol(exportEquals); + if (shouldTreatPropertiesOfExternalModuleAsExports(type)) { + addRange(exports, getPropertiesOfType(type)); + } + } + return exports; + } + + function forEachExportAndPropertyOfModule(moduleSymbol: Symbol, cb: (symbol: Symbol, key: __String) => void): void { + const exports = getExportsOfModule(moduleSymbol); + exports.forEach((symbol, key) => { + if (!isReservedMemberName(key)) { + cb(symbol, key); + } + }); + const exportEquals = resolveExternalModuleSymbol(moduleSymbol); + if (exportEquals !== moduleSymbol) { + const type = getTypeOfSymbol(exportEquals); + if (shouldTreatPropertiesOfExternalModuleAsExports(type)) { + forEachPropertyOfType(type, (symbol, escapedName) => { + cb(symbol, escapedName); + }); + } + } + } + + function tryGetMemberInModuleExports(memberName: __String, moduleSymbol: Symbol): Symbol | undefined { + const symbolTable = getExportsOfModule(moduleSymbol); + if (symbolTable) { + return symbolTable.get(memberName); + } + } + + function tryGetMemberInModuleExportsAndProperties(memberName: __String, moduleSymbol: Symbol): Symbol | undefined { + const symbol = tryGetMemberInModuleExports(memberName, moduleSymbol); + if (symbol) { + return symbol; + } + + const exportEquals = resolveExternalModuleSymbol(moduleSymbol); + if (exportEquals === moduleSymbol) { + return undefined; + } + + const type = getTypeOfSymbol(exportEquals); + return shouldTreatPropertiesOfExternalModuleAsExports(type) ? getPropertyOfType(type, memberName) : undefined; + } + + function shouldTreatPropertiesOfExternalModuleAsExports(resolvedExternalModuleType: Type) { + return !(resolvedExternalModuleType.flags & TypeFlags.Primitive || + getObjectFlags(resolvedExternalModuleType) & ObjectFlags.Class || + // `isArrayOrTupleLikeType` is too expensive to use in this auto-imports hot path + isArrayType(resolvedExternalModuleType) || + isTupleType(resolvedExternalModuleType)); + } + + function getExportsOfSymbol(symbol: Symbol): SymbolTable { + return symbol.flags & SymbolFlags.LateBindingContainer ? getResolvedMembersOrExportsOfSymbol(symbol, MembersOrExportsResolutionKind.resolvedExports) : + symbol.flags & SymbolFlags.Module ? getExportsOfModule(symbol) : + symbol.exports || emptySymbols; + } + + function getExportsOfModule(moduleSymbol: Symbol): SymbolTable { + const links = getSymbolLinks(moduleSymbol); + if (!links.resolvedExports) { + const { exports, typeOnlyExportStarMap } = getExportsOfModuleWorker(moduleSymbol); + links.resolvedExports = exports; + links.typeOnlyExportStarMap = typeOnlyExportStarMap; + } + return links.resolvedExports; + } + + interface ExportCollisionTracker { + specifierText: string; + exportsWithDuplicate?: ExportDeclaration[]; + } + + type ExportCollisionTrackerTable = Map<__String, ExportCollisionTracker>; + + /** + * Extends one symbol table with another while collecting information on name collisions for error message generation into the `lookupTable` argument + * Not passing `lookupTable` and `exportNode` disables this collection, and just extends the tables + */ + function extendExportSymbols(target: SymbolTable, source: SymbolTable | undefined, lookupTable?: ExportCollisionTrackerTable, exportNode?: ExportDeclaration) { + if (!source) return; + source.forEach((sourceSymbol, id) => { + if (id === InternalSymbolName.Default) return; + + const targetSymbol = target.get(id); + if (!targetSymbol) { + target.set(id, sourceSymbol); + if (lookupTable && exportNode) { + lookupTable.set(id, { + specifierText: getTextOfNode(exportNode.moduleSpecifier!), + }); + } + } + else if (lookupTable && exportNode && targetSymbol && resolveSymbol(targetSymbol) !== resolveSymbol(sourceSymbol)) { + const collisionTracker = lookupTable.get(id)!; + if (!collisionTracker.exportsWithDuplicate) { + collisionTracker.exportsWithDuplicate = [exportNode]; + } + else { + collisionTracker.exportsWithDuplicate.push(exportNode); + } + } + }); + } + + function getExportsOfModuleWorker(moduleSymbol: Symbol) { + const visitedSymbols: Symbol[] = []; + let typeOnlyExportStarMap: Map<__String, ExportDeclaration & { readonly isTypeOnly: true; readonly moduleSpecifier: Expression; }> | undefined; + const nonTypeOnlyNames = new Set<__String>(); + + // A module defined by an 'export=' consists of one export that needs to be resolved + moduleSymbol = resolveExternalModuleSymbol(moduleSymbol); + const exports = visit(moduleSymbol) || emptySymbols; + + if (typeOnlyExportStarMap) { + nonTypeOnlyNames.forEach(name => typeOnlyExportStarMap!.delete(name)); + } + + return { + exports, + typeOnlyExportStarMap, + }; + + // The ES6 spec permits export * declarations in a module to circularly reference the module itself. For example, + // module 'a' can 'export * from "b"' and 'b' can 'export * from "a"' without error. + function visit(symbol: Symbol | undefined, exportStar?: ExportDeclaration, isTypeOnly?: boolean): SymbolTable | undefined { + if (!isTypeOnly && symbol?.exports) { + // Add non-type-only names before checking if we've visited this module, + // because we might have visited it via an 'export type *', and visiting + // again with 'export *' will override the type-onlyness of its exports. + symbol.exports.forEach((_, name) => nonTypeOnlyNames.add(name)); + } + if (!(symbol && symbol.exports && pushIfUnique(visitedSymbols, symbol))) { + return; + } + const symbols = new Map(symbol.exports); + + // All export * declarations are collected in an __export symbol by the binder + const exportStars = symbol.exports.get(InternalSymbolName.ExportStar); + if (exportStars) { + const nestedSymbols = createSymbolTable(); + const lookupTable: ExportCollisionTrackerTable = new Map(); + if (exportStars.declarations) { + for (const node of exportStars.declarations) { + const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!); + const exportedSymbols = visit(resolvedModule, node as ExportDeclaration, isTypeOnly || (node as ExportDeclaration).isTypeOnly); + extendExportSymbols( + nestedSymbols, + exportedSymbols, + lookupTable, + node as ExportDeclaration, + ); + } + } + lookupTable.forEach(({ exportsWithDuplicate }, id) => { + // It's not an error if the file with multiple `export *`s with duplicate names exports a member with that name itself + if (id === "export=" || !(exportsWithDuplicate && exportsWithDuplicate.length) || symbols.has(id)) { + return; + } + for (const node of exportsWithDuplicate) { + diagnostics.add(createDiagnosticForNode( + node, + Diagnostics.Module_0_has_already_exported_a_member_named_1_Consider_explicitly_re_exporting_to_resolve_the_ambiguity, + lookupTable.get(id)!.specifierText, + unescapeLeadingUnderscores(id), + )); + } + }); + extendExportSymbols(symbols, nestedSymbols); + } + if (exportStar?.isTypeOnly) { + typeOnlyExportStarMap ??= new Map(); + symbols.forEach((_, escapedName) => + typeOnlyExportStarMap!.set( + escapedName, + exportStar as ExportDeclaration & { readonly isTypeOnly: true; readonly moduleSpecifier: Expression; }, + ) + ); + } + return symbols; + } + } + + function getMergedSymbol(symbol: Symbol): Symbol; + function getMergedSymbol(symbol: Symbol | undefined): Symbol | undefined; + function getMergedSymbol(symbol: Symbol | undefined): Symbol | undefined { + let merged: Symbol; + return symbol && symbol.mergeId && (merged = mergedSymbols[symbol.mergeId]) ? merged : symbol; + } + + function getSymbolOfDeclaration(node: Declaration): Symbol { + return getMergedSymbol(node.symbol && getLateBoundSymbol(node.symbol)); + } + + /** + * Get the merged symbol for a node. If you know the node is a `Declaration`, it is faster and more type safe to + * use use `getSymbolOfDeclaration` instead. + */ + function getSymbolOfNode(node: Node): Symbol | undefined { + return canHaveSymbol(node) ? getSymbolOfDeclaration(node) : undefined; + } + + function getParentOfSymbol(symbol: Symbol): Symbol | undefined { + return getMergedSymbol(symbol.parent && getLateBoundSymbol(symbol.parent)); + } + + function getFunctionExpressionParentSymbolOrSymbol(symbol: Symbol) { + return symbol.valueDeclaration?.kind === SyntaxKind.ArrowFunction || symbol.valueDeclaration?.kind === SyntaxKind.FunctionExpression + ? getSymbolOfNode(symbol.valueDeclaration.parent) || symbol + : symbol; + } + + function getAlternativeContainingModules(symbol: Symbol, enclosingDeclaration: Node): Symbol[] { + const containingFile = getSourceFileOfNode(enclosingDeclaration); + const id = getNodeId(containingFile); + const links = getSymbolLinks(symbol); + let results: Symbol[] | undefined; + if (links.extendedContainersByFile && (results = links.extendedContainersByFile.get(id))) { + return results; + } + if (containingFile && containingFile.imports) { + // Try to make an import using an import already in the enclosing file, if possible + for (const importRef of containingFile.imports) { + if (nodeIsSynthesized(importRef)) continue; // Synthetic names can't be resolved by `resolveExternalModuleName` - they'll cause a debug assert if they error + const resolvedModule = resolveExternalModuleName(enclosingDeclaration, importRef, /*ignoreErrors*/ true); + if (!resolvedModule) continue; + const ref = getAliasForSymbolInContainer(resolvedModule, symbol); + if (!ref) continue; + results = append(results, resolvedModule); + } + if (length(results)) { + (links.extendedContainersByFile || (links.extendedContainersByFile = new Map())).set(id, results!); + return results!; + } + } + if (links.extendedContainers) { + return links.extendedContainers; + } + // No results from files already being imported by this file - expand search (expensive, but not location-specific, so cached) + const otherFiles = host.getSourceFiles(); + for (const file of otherFiles) { + if (!isExternalModule(file)) continue; + const sym = getSymbolOfDeclaration(file); + const ref = getAliasForSymbolInContainer(sym, symbol); + if (!ref) continue; + results = append(results, sym); + } + return links.extendedContainers = results || emptyArray; + } + + /** + * Attempts to find the symbol corresponding to the container a symbol is in - usually this + * is just its' `.parent`, but for locals, this value is `undefined` + */ + function getContainersOfSymbol(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags): Symbol[] | undefined { + const container = getParentOfSymbol(symbol); + // Type parameters end up in the `members` lists but are not externally visible + if (container && !(symbol.flags & SymbolFlags.TypeParameter)) { + return getWithAlternativeContainers(container); + } + const candidates = mapDefined(symbol.declarations, d => { + if (!isAmbientModule(d) && d.parent) { + // direct children of a module + if (hasNonGlobalAugmentationExternalModuleSymbol(d.parent)) { + return getSymbolOfDeclaration(d.parent as Declaration); + } + // export ='d member of an ambient module + if (isModuleBlock(d.parent) && d.parent.parent && resolveExternalModuleSymbol(getSymbolOfDeclaration(d.parent.parent)) === symbol) { + return getSymbolOfDeclaration(d.parent.parent); + } + } + if (isClassExpression(d) && isBinaryExpression(d.parent) && d.parent.operatorToken.kind === SyntaxKind.EqualsToken && isAccessExpression(d.parent.left) && isEntityNameExpression(d.parent.left.expression)) { + if (isModuleExportsAccessExpression(d.parent.left) || isExportsIdentifier(d.parent.left.expression)) { + return getSymbolOfDeclaration(getSourceFileOfNode(d)); + } + checkExpressionCached(d.parent.left.expression); + return getNodeLinks(d.parent.left.expression).resolvedSymbol; + } + }); + if (!length(candidates)) { + return undefined; + } + const containers = mapDefined(candidates, candidate => getAliasForSymbolInContainer(candidate, symbol) ? candidate : undefined); + + let bestContainers: Symbol[] = []; + let alternativeContainers: Symbol[] = []; + + for (const container of containers) { + const [bestMatch, ...rest] = getWithAlternativeContainers(container); + bestContainers = append(bestContainers, bestMatch); + alternativeContainers = addRange(alternativeContainers, rest); + } + + return concatenate(bestContainers, alternativeContainers); + + function getWithAlternativeContainers(container: Symbol) { + const additionalContainers = mapDefined(container.declarations, fileSymbolIfFileSymbolExportEqualsContainer); + const reexportContainers = enclosingDeclaration && getAlternativeContainingModules(symbol, enclosingDeclaration); + const objectLiteralContainer = getVariableDeclarationOfObjectLiteral(container, meaning); + if ( + enclosingDeclaration && + container.flags & getQualifiedLeftMeaning(meaning) && + getAccessibleSymbolChain(container, enclosingDeclaration, SymbolFlags.Namespace, /*useOnlyExternalAliasing*/ false) + ) { + return append(concatenate(concatenate([container], additionalContainers), reexportContainers), objectLiteralContainer); // This order expresses a preference for the real container if it is in scope + } + // we potentially have a symbol which is a member of the instance side of something - look for a variable in scope with the container's type + // which may be acting like a namespace (eg, `Symbol` acts like a namespace when looking up `Symbol.toStringTag`) + const firstVariableMatch = !(container.flags & getQualifiedLeftMeaning(meaning)) + && container.flags & SymbolFlags.Type + && getDeclaredTypeOfSymbol(container).flags & TypeFlags.Object + && meaning === SymbolFlags.Value + ? forEachSymbolTableInScope(enclosingDeclaration, t => { + return forEachEntry(t, s => { + if (s.flags & getQualifiedLeftMeaning(meaning) && getTypeOfSymbol(s) === getDeclaredTypeOfSymbol(container)) { + return s; + } + }); + }) : undefined; + let res = firstVariableMatch ? [firstVariableMatch, ...additionalContainers, container] : [...additionalContainers, container]; + res = append(res, objectLiteralContainer); + res = addRange(res, reexportContainers); + return res; + } + + function fileSymbolIfFileSymbolExportEqualsContainer(d: Declaration) { + return container && getFileSymbolIfFileSymbolExportEqualsContainer(d, container); + } + } + + function getVariableDeclarationOfObjectLiteral(symbol: Symbol, meaning: SymbolFlags) { + // If we're trying to reference some object literal in, eg `var a = { x: 1 }`, the symbol for the literal, `__object`, is distinct + // from the symbol of the declaration it is being assigned to. Since we can use the declaration to refer to the literal, however, + // we'd like to make that connection here - potentially causing us to paint the declaration's visibility, and therefore the literal. + const firstDecl: Node | false = !!length(symbol.declarations) && first(symbol.declarations!); + if (meaning & SymbolFlags.Value && firstDecl && firstDecl.parent && isVariableDeclaration(firstDecl.parent)) { + if (isObjectLiteralExpression(firstDecl) && firstDecl === firstDecl.parent.initializer || isTypeLiteralNode(firstDecl) && firstDecl === firstDecl.parent.type) { + return getSymbolOfDeclaration(firstDecl.parent); + } + } + } + + function getFileSymbolIfFileSymbolExportEqualsContainer(d: Declaration, container: Symbol) { + const fileSymbol = getExternalModuleContainer(d); + const exported = fileSymbol && fileSymbol.exports && fileSymbol.exports.get(InternalSymbolName.ExportEquals); + return exported && getSymbolIfSameReference(exported, container) ? fileSymbol : undefined; + } + + function getAliasForSymbolInContainer(container: Symbol, symbol: Symbol) { + if (container === getParentOfSymbol(symbol)) { + // fast path, `symbol` is either already the alias or isn't aliased + return symbol; + } + // Check if container is a thing with an `export=` which points directly at `symbol`, and if so, return + // the container itself as the alias for the symbol + const exportEquals = container.exports && container.exports.get(InternalSymbolName.ExportEquals); + if (exportEquals && getSymbolIfSameReference(exportEquals, symbol)) { + return container; + } + const exports = getExportsOfSymbol(container); + const quick = exports.get(symbol.escapedName); + if (quick && getSymbolIfSameReference(quick, symbol)) { + return quick; + } + return forEachEntry(exports, exported => { + if (getSymbolIfSameReference(exported, symbol)) { + return exported; + } + }); + } + + /** + * Checks if two symbols, through aliasing and/or merging, refer to the same thing + */ + function getSymbolIfSameReference(s1: Symbol, s2: Symbol) { + if (getMergedSymbol(resolveSymbol(getMergedSymbol(s1))) === getMergedSymbol(resolveSymbol(getMergedSymbol(s2)))) { + return s1; + } + } + + function getExportSymbolOfValueSymbolIfExported(symbol: Symbol): Symbol; + function getExportSymbolOfValueSymbolIfExported(symbol: Symbol | undefined): Symbol | undefined; + function getExportSymbolOfValueSymbolIfExported(symbol: Symbol | undefined): Symbol | undefined { + return getMergedSymbol(symbol && (symbol.flags & SymbolFlags.ExportValue) !== 0 && symbol.exportSymbol || symbol); + } + + function symbolIsValue(symbol: Symbol, includeTypeOnlyMembers?: boolean): boolean { + return !!( + symbol.flags & SymbolFlags.Value || + symbol.flags & SymbolFlags.Alias && getSymbolFlags(symbol, !includeTypeOnlyMembers) & SymbolFlags.Value + ); + } + + function createType(flags: TypeFlags): Type { + const result = new Type(checker, flags); + typeCount++; + result.id = typeCount; + tracing?.recordType(result); + return result; + } + + function createTypeWithSymbol(flags: TypeFlags, symbol: Symbol): Type { + const result = createType(flags); + result.symbol = symbol; + return result; + } + + function createOriginType(flags: TypeFlags): Type { + return new Type(checker, flags); + } + + function createIntrinsicType(kind: TypeFlags, intrinsicName: string, objectFlags = ObjectFlags.None, debugIntrinsicName?: string): IntrinsicType { + checkIntrinsicName(intrinsicName, debugIntrinsicName); + const type = createType(kind) as IntrinsicType; + type.intrinsicName = intrinsicName; + type.debugIntrinsicName = debugIntrinsicName; + type.objectFlags = objectFlags | ObjectFlags.CouldContainTypeVariablesComputed | ObjectFlags.IsGenericTypeComputed | ObjectFlags.IsUnknownLikeUnionComputed | ObjectFlags.IsNeverIntersectionComputed; + return type; + } + + function checkIntrinsicName(name: string, debug: string | undefined) { + const key = `${name},${debug ?? ""}`; + if (seenIntrinsicNames.has(key)) { + Debug.fail(`Duplicate intrinsic type name ${name}${debug ? ` (${debug})` : ""}; you may need to pass a name to createIntrinsicType.`); + } + seenIntrinsicNames.add(key); + } + + function createObjectType(objectFlags: ObjectFlags, symbol?: Symbol): ObjectType { + const type = createTypeWithSymbol(TypeFlags.Object, symbol!) as ObjectType; + type.objectFlags = objectFlags; + type.members = undefined; + type.properties = undefined; + type.callSignatures = undefined; + type.constructSignatures = undefined; + type.indexInfos = undefined; + return type; + } + + function createTypeofType() { + return getUnionType(arrayFrom(typeofNEFacts.keys(), getStringLiteralType)); + } + + function createTypeParameter(symbol?: Symbol) { + return createTypeWithSymbol(TypeFlags.TypeParameter, symbol!) as TypeParameter; + } + + // A reserved member name starts with two underscores, but the third character cannot be an underscore, + // @, or #. A third underscore indicates an escaped form of an identifier that started + // with at least two underscores. The @ character indicates that the name is denoted by a well known ES + // Symbol instance and the # character indicates that the name is a PrivateIdentifier. + function isReservedMemberName(name: __String) { + return (name as string).charCodeAt(0) === CharacterCodes._ && + (name as string).charCodeAt(1) === CharacterCodes._ && + (name as string).charCodeAt(2) !== CharacterCodes._ && + (name as string).charCodeAt(2) !== CharacterCodes.at && + (name as string).charCodeAt(2) !== CharacterCodes.hash; + } + + function getNamedMembers(members: SymbolTable): Symbol[] { + let result: Symbol[] | undefined; + members.forEach((symbol, id) => { + if (isNamedMember(symbol, id)) { + (result || (result = [])).push(symbol); + } + }); + return result || emptyArray; + } + + function isNamedMember(member: Symbol, escapedName: __String) { + return !isReservedMemberName(escapedName) && symbolIsValue(member); + } + + function getNamedOrIndexSignatureMembers(members: SymbolTable): Symbol[] { + const result = getNamedMembers(members); + const index = getIndexSymbolFromSymbolTable(members); + return index ? concatenate(result, [index]) : result; + } + + function setStructuredTypeMembers(type: StructuredType, members: SymbolTable, callSignatures: readonly Signature[], constructSignatures: readonly Signature[], indexInfos: readonly IndexInfo[]): ResolvedType { + const resolved = type as ResolvedType; + resolved.members = members; + resolved.properties = emptyArray; + resolved.callSignatures = callSignatures; + resolved.constructSignatures = constructSignatures; + resolved.indexInfos = indexInfos; + // This can loop back to getPropertyOfType() which would crash if `callSignatures` & `constructSignatures` are not initialized. + if (members !== emptySymbols) resolved.properties = getNamedMembers(members); + return resolved; + } + + function createAnonymousType(symbol: Symbol | undefined, members: SymbolTable, callSignatures: readonly Signature[], constructSignatures: readonly Signature[], indexInfos: readonly IndexInfo[]): ResolvedType { + return setStructuredTypeMembers(createObjectType(ObjectFlags.Anonymous, symbol), members, callSignatures, constructSignatures, indexInfos); + } + + function getResolvedTypeWithoutAbstractConstructSignatures(type: ResolvedType) { + if (type.constructSignatures.length === 0) return type; + if (type.objectTypeWithoutAbstractConstructSignatures) return type.objectTypeWithoutAbstractConstructSignatures; + const constructSignatures = filter(type.constructSignatures, signature => !(signature.flags & SignatureFlags.Abstract)); + if (type.constructSignatures === constructSignatures) return type; + const typeCopy = createAnonymousType( + type.symbol, + type.members, + type.callSignatures, + some(constructSignatures) ? constructSignatures : emptyArray, + type.indexInfos, + ); + type.objectTypeWithoutAbstractConstructSignatures = typeCopy; + typeCopy.objectTypeWithoutAbstractConstructSignatures = typeCopy; + return typeCopy; + } + + function forEachSymbolTableInScope(enclosingDeclaration: Node | undefined, callback: (symbolTable: SymbolTable, ignoreQualification?: boolean, isLocalNameLookup?: boolean, scopeNode?: Node) => T): T { + let result: T; + for (let location = enclosingDeclaration; location; location = location.parent) { + // Locals of a source file are not in scope (because they get merged into the global symbol table) + if (canHaveLocals(location) && location.locals && !isGlobalSourceFile(location)) { + if (result = callback(location.locals, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true, location)) { + return result; + } + } + switch (location.kind) { + case SyntaxKind.SourceFile: + if (!isExternalOrCommonJsModule(location as SourceFile)) { + break; + } + // falls through + case SyntaxKind.ModuleDeclaration: + const sym = getSymbolOfDeclaration(location as ModuleDeclaration); + // `sym` may not have exports if this module declaration is backed by the symbol for a `const` that's being rewritten + // into a namespace - in such cases, it's best to just let the namespace appear empty (the const members couldn't have referred + // to one another anyway) + if (result = callback(sym?.exports || emptySymbols, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true, location)) { + return result; + } + break; + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + case SyntaxKind.InterfaceDeclaration: + // Type parameters are bound into `members` lists so they can merge across declarations + // This is troublesome, since in all other respects, they behave like locals :cries: + // TODO: the below is shared with similar code in `resolveName` - in fact, rephrasing all this symbol + // lookup logic in terms of `resolveName` would be nice + // The below is used to lookup type parameters within a class or interface, as they are added to the class/interface locals + // These can never be latebound, so the symbol's raw members are sufficient. `getMembersOfNode` cannot be used, as it would + // trigger resolving late-bound names, which we may already be in the process of doing while we're here! + let table: Map<__String, Symbol> | undefined; + // TODO: Should this filtered table be cached in some way? + (getSymbolOfDeclaration(location as ClassLikeDeclaration | InterfaceDeclaration).members || emptySymbols).forEach((memberSymbol, key) => { + if (memberSymbol.flags & (SymbolFlags.Type & ~SymbolFlags.Assignment)) { + (table || (table = createSymbolTable())).set(key, memberSymbol); + } + }); + if (table && (result = callback(table, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ false, location))) { + return result; + } + break; + } + } + + return callback(globals, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true); + } + + function getQualifiedLeftMeaning(rightMeaning: SymbolFlags) { + // If we are looking in value space, the parent meaning is value, other wise it is namespace + return rightMeaning === SymbolFlags.Value ? SymbolFlags.Value : SymbolFlags.Namespace; + } + + function getAccessibleSymbolChain(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, useOnlyExternalAliasing: boolean, visitedSymbolTablesMap = new Map()): Symbol[] | undefined { + if (!(symbol && !isPropertyOrMethodDeclarationSymbol(symbol))) { + return undefined; + } + const links = getSymbolLinks(symbol); + const cache = (links.accessibleChainCache ||= new Map()); + // Go from enclosingDeclaration to the first scope we check, so the cache is keyed off the scope and thus shared more + const firstRelevantLocation = forEachSymbolTableInScope(enclosingDeclaration, (_, __, ___, node) => node); + const key = `${useOnlyExternalAliasing ? 0 : 1}|${firstRelevantLocation && getNodeId(firstRelevantLocation)}|${meaning}`; + if (cache.has(key)) { + return cache.get(key); + } + + const id = getSymbolId(symbol); + let visitedSymbolTables = visitedSymbolTablesMap.get(id); + if (!visitedSymbolTables) { + visitedSymbolTablesMap.set(id, visitedSymbolTables = []); + } + const result = forEachSymbolTableInScope(enclosingDeclaration, getAccessibleSymbolChainFromSymbolTable); + cache.set(key, result); + return result; + + /** + * @param {ignoreQualification} boolean Set when a symbol is being looked for through the exports of another symbol (meaning we have a route to qualify it already) + */ + function getAccessibleSymbolChainFromSymbolTable(symbols: SymbolTable, ignoreQualification?: boolean, isLocalNameLookup?: boolean): Symbol[] | undefined { + if (!pushIfUnique(visitedSymbolTables!, symbols)) { + return undefined; + } + + const result = trySymbolTable(symbols, ignoreQualification, isLocalNameLookup); + visitedSymbolTables!.pop(); + return result; + } + + function canQualifySymbol(symbolFromSymbolTable: Symbol, meaning: SymbolFlags) { + // If the symbol is equivalent and doesn't need further qualification, this symbol is accessible + return !needsQualification(symbolFromSymbolTable, enclosingDeclaration, meaning) || + // If symbol needs qualification, make sure that parent is accessible, if it is then this symbol is accessible too + !!getAccessibleSymbolChain(symbolFromSymbolTable.parent, enclosingDeclaration, getQualifiedLeftMeaning(meaning), useOnlyExternalAliasing, visitedSymbolTablesMap); + } + + function isAccessible(symbolFromSymbolTable: Symbol, resolvedAliasSymbol?: Symbol, ignoreQualification?: boolean) { + return (symbol === (resolvedAliasSymbol || symbolFromSymbolTable) || getMergedSymbol(symbol) === getMergedSymbol(resolvedAliasSymbol || symbolFromSymbolTable)) && + // if the symbolFromSymbolTable is not external module (it could be if it was determined as ambient external module and would be in globals table) + // and if symbolFromSymbolTable or alias resolution matches the symbol, + // check the symbol can be qualified, it is only then this symbol is accessible + !some(symbolFromSymbolTable.declarations, hasNonGlobalAugmentationExternalModuleSymbol) && + (ignoreQualification || canQualifySymbol(getMergedSymbol(symbolFromSymbolTable), meaning)); + } + + function trySymbolTable(symbols: SymbolTable, ignoreQualification: boolean | undefined, isLocalNameLookup: boolean | undefined): Symbol[] | undefined { + // If symbol is directly available by its name in the symbol table + if (isAccessible(symbols.get(symbol!.escapedName)!, /*resolvedAliasSymbol*/ undefined, ignoreQualification)) { + return [symbol!]; + } + + // Check if symbol is any of the aliases in scope + const result = forEachEntry(symbols, symbolFromSymbolTable => { + if ( + symbolFromSymbolTable.flags & SymbolFlags.Alias + && symbolFromSymbolTable.escapedName !== InternalSymbolName.ExportEquals + && symbolFromSymbolTable.escapedName !== InternalSymbolName.Default + && !(isUMDExportSymbol(symbolFromSymbolTable) && enclosingDeclaration && isExternalModule(getSourceFileOfNode(enclosingDeclaration))) + // If `!useOnlyExternalAliasing`, we can use any type of alias to get the name + && (!useOnlyExternalAliasing || some(symbolFromSymbolTable.declarations, isExternalModuleImportEqualsDeclaration)) + // If we're looking up a local name to reference directly, omit namespace reexports, otherwise when we're trawling through an export list to make a dotted name, we can keep it + && (isLocalNameLookup ? !some(symbolFromSymbolTable.declarations, isNamespaceReexportDeclaration) : true) + // While exports are generally considered to be in scope, export-specifier declared symbols are _not_ + // See similar comment in `resolveName` for details + && (ignoreQualification || !getDeclarationOfKind(symbolFromSymbolTable, SyntaxKind.ExportSpecifier)) + ) { + const resolvedImportedSymbol = resolveAlias(symbolFromSymbolTable); + const candidate = getCandidateListForSymbol(symbolFromSymbolTable, resolvedImportedSymbol, ignoreQualification); + if (candidate) { + return candidate; + } + } + if (symbolFromSymbolTable.escapedName === symbol!.escapedName && symbolFromSymbolTable.exportSymbol) { + if (isAccessible(getMergedSymbol(symbolFromSymbolTable.exportSymbol), /*resolvedAliasSymbol*/ undefined, ignoreQualification)) { + return [symbol!]; + } + } + }); + + // If there's no result and we're looking at the global symbol table, treat `globalThis` like an alias and try to lookup thru that + return result || (symbols === globals ? getCandidateListForSymbol(globalThisSymbol, globalThisSymbol, ignoreQualification) : undefined); + } + + function getCandidateListForSymbol(symbolFromSymbolTable: Symbol, resolvedImportedSymbol: Symbol, ignoreQualification: boolean | undefined) { + if (isAccessible(symbolFromSymbolTable, resolvedImportedSymbol, ignoreQualification)) { + return [symbolFromSymbolTable]; + } + + // Look in the exported members, if we can find accessibleSymbolChain, symbol is accessible using this chain + // but only if the symbolFromSymbolTable can be qualified + const candidateTable = getExportsOfSymbol(resolvedImportedSymbol); + const accessibleSymbolsFromExports = candidateTable && getAccessibleSymbolChainFromSymbolTable(candidateTable, /*ignoreQualification*/ true); + if (accessibleSymbolsFromExports && canQualifySymbol(symbolFromSymbolTable, getQualifiedLeftMeaning(meaning))) { + return [symbolFromSymbolTable].concat(accessibleSymbolsFromExports); + } + } + } + + function needsQualification(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags) { + let qualify = false; + forEachSymbolTableInScope(enclosingDeclaration, symbolTable => { + // If symbol of this name is not available in the symbol table we are ok + let symbolFromSymbolTable = getMergedSymbol(symbolTable.get(symbol.escapedName)); + if (!symbolFromSymbolTable) { + // Continue to the next symbol table + return false; + } + // If the symbol with this name is present it should refer to the symbol + if (symbolFromSymbolTable === symbol) { + // No need to qualify + return true; + } + + // Qualify if the symbol from symbol table has same meaning as expected + const shouldResolveAlias = symbolFromSymbolTable.flags & SymbolFlags.Alias && !getDeclarationOfKind(symbolFromSymbolTable, SyntaxKind.ExportSpecifier); + symbolFromSymbolTable = shouldResolveAlias ? resolveAlias(symbolFromSymbolTable) : symbolFromSymbolTable; + const flags = shouldResolveAlias ? getSymbolFlags(symbolFromSymbolTable) : symbolFromSymbolTable.flags; + if (flags & meaning) { + qualify = true; + return true; + } + + // Continue to the next symbol table + return false; + }); + + return qualify; + } + + function isPropertyOrMethodDeclarationSymbol(symbol: Symbol) { + if (symbol.declarations && symbol.declarations.length) { + for (const declaration of symbol.declarations) { + switch (declaration.kind) { + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + continue; + default: + return false; + } + } + return true; + } + return false; + } + + function isTypeSymbolAccessible(typeSymbol: Symbol, enclosingDeclaration: Node | undefined): boolean { + const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, SymbolFlags.Type, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ true); + return access.accessibility === SymbolAccessibility.Accessible; + } + + function isValueSymbolAccessible(typeSymbol: Symbol, enclosingDeclaration: Node | undefined): boolean { + const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, SymbolFlags.Value, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ true); + return access.accessibility === SymbolAccessibility.Accessible; + } + + function isSymbolAccessibleByFlags(typeSymbol: Symbol, enclosingDeclaration: Node | undefined, flags: SymbolFlags): boolean { + const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, flags, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ false); + return access.accessibility === SymbolAccessibility.Accessible; + } + + function isAnySymbolAccessible(symbols: Symbol[] | undefined, enclosingDeclaration: Node | undefined, initialSymbol: Symbol, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean, allowModules: boolean): SymbolAccessibilityResult | undefined { + if (!length(symbols)) return; + + let hadAccessibleChain: Symbol | undefined; + let earlyModuleBail = false; + for (const symbol of symbols!) { + // Symbol is accessible if it by itself is accessible + const accessibleSymbolChain = getAccessibleSymbolChain(symbol, enclosingDeclaration, meaning, /*useOnlyExternalAliasing*/ false); + if (accessibleSymbolChain) { + hadAccessibleChain = symbol; + const hasAccessibleDeclarations = hasVisibleDeclarations(accessibleSymbolChain[0], shouldComputeAliasesToMakeVisible); + if (hasAccessibleDeclarations) { + return hasAccessibleDeclarations; + } + } + if (allowModules) { + if (some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + if (shouldComputeAliasesToMakeVisible) { + earlyModuleBail = true; + // Generally speaking, we want to use the aliases that already exist to refer to a module, if present + // In order to do so, we need to find those aliases in order to retain them in declaration emit; so + // if we are in declaration emit, we cannot use the fast path for module visibility until we've exhausted + // all other visibility options (in order to capture the possible aliases used to reference the module) + continue; + } + // Any meaning of a module symbol is always accessible via an `import` type + return { + accessibility: SymbolAccessibility.Accessible, + }; + } + } + + // If we haven't got the accessible symbol, it doesn't mean the symbol is actually inaccessible. + // It could be a qualified symbol and hence verify the path + // e.g.: + // module m { + // export class c { + // } + // } + // const x: typeof m.c + // In the above example when we start with checking if typeof m.c symbol is accessible, + // we are going to see if c can be accessed in scope directly. + // But it can't, hence the accessible is going to be undefined, but that doesn't mean m.c is inaccessible + // It is accessible if the parent m is accessible because then m.c can be accessed through qualification + + const containers = getContainersOfSymbol(symbol, enclosingDeclaration, meaning); + const parentResult = isAnySymbolAccessible(containers, enclosingDeclaration, initialSymbol, initialSymbol === symbol ? getQualifiedLeftMeaning(meaning) : meaning, shouldComputeAliasesToMakeVisible, allowModules); + if (parentResult) { + return parentResult; + } + } + + if (earlyModuleBail) { + return { + accessibility: SymbolAccessibility.Accessible, + }; + } + + if (hadAccessibleChain) { + return { + accessibility: SymbolAccessibility.NotAccessible, + errorSymbolName: symbolToString(initialSymbol, enclosingDeclaration, meaning), + errorModuleName: hadAccessibleChain !== initialSymbol ? symbolToString(hadAccessibleChain, enclosingDeclaration, SymbolFlags.Namespace) : undefined, + }; + } + } + + /** + * Check if the given symbol in given enclosing declaration is accessible and mark all associated alias to be visible if requested + * + * @param symbol a Symbol to check if accessible + * @param enclosingDeclaration a Node containing reference to the symbol + * @param meaning a SymbolFlags to check if such meaning of the symbol is accessible + * @param shouldComputeAliasToMakeVisible a boolean value to indicate whether to return aliases to be mark visible in case the symbol is accessible + */ + function isSymbolAccessible(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean): SymbolAccessibilityResult { + return isSymbolAccessibleWorker(symbol, enclosingDeclaration, meaning, shouldComputeAliasesToMakeVisible, /*allowModules*/ true); + } + + function isSymbolAccessibleWorker(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean, allowModules: boolean): SymbolAccessibilityResult { + if (symbol && enclosingDeclaration) { + const result = isAnySymbolAccessible([symbol], enclosingDeclaration, symbol, meaning, shouldComputeAliasesToMakeVisible, allowModules); + if (result) { + return result; + } + + // This could be a symbol that is not exported in the external module + // or it could be a symbol from different external module that is not aliased and hence cannot be named + const symbolExternalModule = forEach(symbol.declarations, getExternalModuleContainer); + if (symbolExternalModule) { + const enclosingExternalModule = getExternalModuleContainer(enclosingDeclaration); + if (symbolExternalModule !== enclosingExternalModule) { + // name from different external module that is not visible + return { + accessibility: SymbolAccessibility.CannotBeNamed, + errorSymbolName: symbolToString(symbol, enclosingDeclaration, meaning), + errorModuleName: symbolToString(symbolExternalModule), + errorNode: isInJSFile(enclosingDeclaration) ? enclosingDeclaration : undefined, + }; + } + } + + // Just a local name that is not accessible + return { + accessibility: SymbolAccessibility.NotAccessible, + errorSymbolName: symbolToString(symbol, enclosingDeclaration, meaning), + }; + } + + return { accessibility: SymbolAccessibility.Accessible }; + } + + function getExternalModuleContainer(declaration: Node) { + const node = findAncestor(declaration, hasExternalModuleSymbol); + return node && getSymbolOfDeclaration(node as AmbientModuleDeclaration | SourceFile); + } + + function hasExternalModuleSymbol(declaration: Node) { + return isAmbientModule(declaration) || (declaration.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(declaration as SourceFile)); + } + + function hasNonGlobalAugmentationExternalModuleSymbol(declaration: Node) { + return isModuleWithStringLiteralName(declaration) || (declaration.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(declaration as SourceFile)); + } + + function hasVisibleDeclarations(symbol: Symbol, shouldComputeAliasToMakeVisible: boolean): SymbolVisibilityResult | undefined { + let aliasesToMakeVisible: LateVisibilityPaintedStatement[] | undefined; + if (!every(filter(symbol.declarations, d => d.kind !== SyntaxKind.Identifier), getIsDeclarationVisible)) { + return undefined; + } + return { accessibility: SymbolAccessibility.Accessible, aliasesToMakeVisible }; + + function getIsDeclarationVisible(declaration: Declaration) { + if (!isDeclarationVisible(declaration)) { + // Mark the unexported alias as visible if its parent is visible + // because these kind of aliases can be used to name types in declaration file + + const anyImportSyntax = getAnyImportSyntax(declaration); + if ( + anyImportSyntax && + !hasSyntacticModifier(anyImportSyntax, ModifierFlags.Export) && // import clause without export + isDeclarationVisible(anyImportSyntax.parent) + ) { + return addVisibleAlias(declaration, anyImportSyntax); + } + else if ( + isVariableDeclaration(declaration) && isVariableStatement(declaration.parent.parent) && + !hasSyntacticModifier(declaration.parent.parent, ModifierFlags.Export) && // unexported variable statement + isDeclarationVisible(declaration.parent.parent.parent) + ) { + return addVisibleAlias(declaration, declaration.parent.parent); + } + else if ( + isLateVisibilityPaintedStatement(declaration) // unexported top-level statement + && !hasSyntacticModifier(declaration, ModifierFlags.Export) + && isDeclarationVisible(declaration.parent) + ) { + return addVisibleAlias(declaration, declaration); + } + else if (isBindingElement(declaration)) { + if ( + symbol.flags & SymbolFlags.Alias && isInJSFile(declaration) && declaration.parent?.parent // exported import-like top-level JS require statement + && isVariableDeclaration(declaration.parent.parent) + && declaration.parent.parent.parent?.parent && isVariableStatement(declaration.parent.parent.parent.parent) + && !hasSyntacticModifier(declaration.parent.parent.parent.parent, ModifierFlags.Export) + && declaration.parent.parent.parent.parent.parent // check if the thing containing the variable statement is visible (ie, the file) + && isDeclarationVisible(declaration.parent.parent.parent.parent.parent) + ) { + return addVisibleAlias(declaration, declaration.parent.parent.parent.parent); + } + else if (symbol.flags & SymbolFlags.BlockScopedVariable) { + const variableStatement = findAncestor(declaration, isVariableStatement)!; + if (hasSyntacticModifier(variableStatement, ModifierFlags.Export)) { + return true; + } + if (!isDeclarationVisible(variableStatement.parent)) { + return false; + } + return addVisibleAlias(declaration, variableStatement); + } + } + + // Declaration is not visible + return false; + } + + return true; + } + + function addVisibleAlias(declaration: Declaration, aliasingStatement: LateVisibilityPaintedStatement) { + // In function "buildTypeDisplay" where we decide whether to write type-alias or serialize types, + // we want to just check if type- alias is accessible or not but we don't care about emitting those alias at that time + // since we will do the emitting later in trackSymbol. + if (shouldComputeAliasToMakeVisible) { + getNodeLinks(declaration).isVisible = true; + aliasesToMakeVisible = appendIfUnique(aliasesToMakeVisible, aliasingStatement); + } + return true; + } + } + + function getMeaningOfEntityNameReference(entityName: EntityNameOrEntityNameExpression): SymbolFlags { + // get symbol of the first identifier of the entityName + let meaning: SymbolFlags; + if ( + entityName.parent.kind === SyntaxKind.TypeQuery || + entityName.parent.kind === SyntaxKind.ExpressionWithTypeArguments && !isPartOfTypeNode(entityName.parent) || + entityName.parent.kind === SyntaxKind.ComputedPropertyName || + entityName.parent.kind === SyntaxKind.TypePredicate && (entityName.parent as TypePredicateNode).parameterName === entityName + ) { + // Typeof value + meaning = SymbolFlags.Value | SymbolFlags.ExportValue; + } + else if ( + entityName.kind === SyntaxKind.QualifiedName || entityName.kind === SyntaxKind.PropertyAccessExpression || + entityName.parent.kind === SyntaxKind.ImportEqualsDeclaration || + (entityName.parent.kind === SyntaxKind.QualifiedName && (entityName.parent as QualifiedName).left === entityName) || + (entityName.parent.kind === SyntaxKind.PropertyAccessExpression && (entityName.parent as PropertyAccessExpression).expression === entityName) || + (entityName.parent.kind === SyntaxKind.ElementAccessExpression && (entityName.parent as ElementAccessExpression).expression === entityName) + ) { + // Left identifier from type reference or TypeAlias + // Entity name of the import declaration + meaning = SymbolFlags.Namespace; + } + else { + // Type Reference or TypeAlias entity = Identifier + meaning = SymbolFlags.Type; + } + return meaning; + } + + function isEntityNameVisible(entityName: EntityNameOrEntityNameExpression, enclosingDeclaration: Node, shouldComputeAliasToMakeVisible = true): SymbolVisibilityResult { + const meaning = getMeaningOfEntityNameReference(entityName); + const firstIdentifier = getFirstIdentifier(entityName); + const symbol = resolveName(enclosingDeclaration, firstIdentifier.escapedText, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (symbol && symbol.flags & SymbolFlags.TypeParameter && meaning & SymbolFlags.Type) { + return { accessibility: SymbolAccessibility.Accessible }; + } + if (!symbol && isThisIdentifier(firstIdentifier) && isSymbolAccessible(getSymbolOfDeclaration(getThisContainer(firstIdentifier, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)), firstIdentifier, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility === SymbolAccessibility.Accessible) { + return { accessibility: SymbolAccessibility.Accessible }; + } + + if (!symbol) { + return { + accessibility: SymbolAccessibility.NotResolved, + errorSymbolName: getTextOfNode(firstIdentifier), + errorNode: firstIdentifier, + }; + } + // Verify if the symbol is accessible + return hasVisibleDeclarations(symbol, shouldComputeAliasToMakeVisible) || { + accessibility: SymbolAccessibility.NotAccessible, + errorSymbolName: getTextOfNode(firstIdentifier), + errorNode: firstIdentifier, + }; + } + + function symbolToString(symbol: Symbol, enclosingDeclaration?: Node, meaning?: SymbolFlags, flags: SymbolFormatFlags = SymbolFormatFlags.AllowAnyNodeKind, writer?: EmitTextWriter): string { + let nodeFlags = NodeBuilderFlags.IgnoreErrors; + if (flags & SymbolFormatFlags.UseOnlyExternalAliasing) { + nodeFlags |= NodeBuilderFlags.UseOnlyExternalAliasing; + } + if (flags & SymbolFormatFlags.WriteTypeParametersOrArguments) { + nodeFlags |= NodeBuilderFlags.WriteTypeParametersInQualifiedName; + } + if (flags & SymbolFormatFlags.UseAliasDefinedOutsideCurrentScope) { + nodeFlags |= NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope; + } + if (flags & SymbolFormatFlags.DoNotIncludeSymbolChain) { + nodeFlags |= NodeBuilderFlags.DoNotIncludeSymbolChain; + } + if (flags & SymbolFormatFlags.WriteComputedProps) { + nodeFlags |= NodeBuilderFlags.WriteComputedProps; + } + const builder = flags & SymbolFormatFlags.AllowAnyNodeKind ? nodeBuilder.symbolToNode : nodeBuilder.symbolToEntityName; + return writer ? symbolToStringWorker(writer).getText() : usingSingleLineStringWriter(symbolToStringWorker); + + function symbolToStringWorker(writer: EmitTextWriter) { + const entity = builder(symbol, meaning!, enclosingDeclaration, nodeFlags)!; // TODO: GH#18217 + // add neverAsciiEscape for GH#39027 + const printer = enclosingDeclaration?.kind === SyntaxKind.SourceFile + ? createPrinterWithRemoveCommentsNeverAsciiEscape() + : createPrinterWithRemoveComments(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, entity, /*sourceFile*/ sourceFile, writer); + return writer; + } + } + + function signatureToString(signature: Signature, enclosingDeclaration?: Node, flags = TypeFormatFlags.None, kind?: SignatureKind, writer?: EmitTextWriter): string { + return writer ? signatureToStringWorker(writer).getText() : usingSingleLineStringWriter(signatureToStringWorker); + + function signatureToStringWorker(writer: EmitTextWriter) { + let sigOutput: SyntaxKind; + if (flags & TypeFormatFlags.WriteArrowStyleSignature) { + sigOutput = kind === SignatureKind.Construct ? SyntaxKind.ConstructorType : SyntaxKind.FunctionType; + } + else { + sigOutput = kind === SignatureKind.Construct ? SyntaxKind.ConstructSignature : SyntaxKind.CallSignature; + } + const sig = nodeBuilder.signatureToSignatureDeclaration(signature, sigOutput, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.WriteTypeParametersInQualifiedName); + const printer = createPrinterWithRemoveCommentsOmitTrailingSemicolon(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, sig!, /*sourceFile*/ sourceFile, getTrailingSemicolonDeferringWriter(writer)); // TODO: GH#18217 + return writer; + } + } + + function typeToString(type: Type, enclosingDeclaration?: Node, flags: TypeFormatFlags = TypeFormatFlags.AllowUniqueESSymbolType | TypeFormatFlags.UseAliasDefinedOutsideCurrentScope, writer: EmitTextWriter = createTextWriter("")): string { + const noTruncation = compilerOptions.noErrorTruncation || flags & TypeFormatFlags.NoTruncation; + const typeNode = nodeBuilder.typeToTypeNode(type, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | (noTruncation ? NodeBuilderFlags.NoTruncation : 0)); + if (typeNode === undefined) return Debug.fail("should always get typenode"); + // The unresolved type gets a synthesized comment on `any` to hint to users that it's not a plain `any`. + // Otherwise, we always strip comments out. + const printer = type !== unresolvedType ? createPrinterWithRemoveComments() : createPrinterWithDefaults(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, typeNode, /*sourceFile*/ sourceFile, writer); + const result = writer.getText(); + + const maxLength = noTruncation ? noTruncationMaximumTruncationLength * 2 : defaultMaximumTruncationLength * 2; + if (maxLength && result && result.length >= maxLength) { + return result.substr(0, maxLength - "...".length) + "..."; + } + return result; + } + + function getTypeNamesForErrorDisplay(left: Type, right: Type): [string, string] { + let leftStr = symbolValueDeclarationIsContextSensitive(left.symbol) ? typeToString(left, left.symbol.valueDeclaration) : typeToString(left); + let rightStr = symbolValueDeclarationIsContextSensitive(right.symbol) ? typeToString(right, right.symbol.valueDeclaration) : typeToString(right); + if (leftStr === rightStr) { + leftStr = getTypeNameForErrorDisplay(left); + rightStr = getTypeNameForErrorDisplay(right); + } + return [leftStr, rightStr]; + } + + function getTypeNameForErrorDisplay(type: Type) { + return typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.UseFullyQualifiedType); + } + + function symbolValueDeclarationIsContextSensitive(symbol: Symbol): boolean { + return symbol && !!symbol.valueDeclaration && isExpression(symbol.valueDeclaration) && !isContextSensitive(symbol.valueDeclaration); + } + + function toNodeBuilderFlags(flags = TypeFormatFlags.None): NodeBuilderFlags { + return flags & TypeFormatFlags.NodeBuilderFlagsMask; + } + + function isClassInstanceSide(type: Type) { + return !!type.symbol && !!(type.symbol.flags & SymbolFlags.Class) && (type === getDeclaredTypeOfClassOrInterface(type.symbol) || (!!(type.flags & TypeFlags.Object) && !!(getObjectFlags(type) & ObjectFlags.IsClassInstanceClone))); + } + /** + * Same as getTypeFromTypeNode, but for use in createNodeBuilder + * Inside createNodeBuilder we shadow getTypeFromTypeNode to make sure anyone using this function will call the local version that does type mapping if appropriate + * This function is used to still be able to call the original getTypeFromTypeNode from the local scope version of getTypeFromTypeNode + */ + function getTypeFromTypeNodeWithoutContext(node: TypeNode) { + return getTypeFromTypeNode(node); + } + function createNodeBuilder() { + return { + typeToTypeNode: (type: Type, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeToTypeNodeHelper(type, context)), + typePredicateToTypePredicateNode: (typePredicate: TypePredicate, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typePredicateToTypePredicateNodeHelper(typePredicate, context)), + expressionOrTypeToTypeNode: (expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => expressionOrTypeToTypeNode(context, expr, type, addUndefined)), + serializeTypeForDeclaration: (declaration: Declaration, type: Type, symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => serializeTypeForDeclaration(context, declaration, type, symbol)), + serializeReturnTypeForSignature: (signature: Signature, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => serializeReturnTypeForSignature(context, signature)), + indexInfoToIndexSignatureDeclaration: (indexInfo: IndexInfo, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => indexInfoToIndexSignatureDeclarationHelper(indexInfo, context, /*typeNode*/ undefined)), + signatureToSignatureDeclaration: (signature: Signature, kind: SignatureDeclaration["kind"], enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => signatureToSignatureDeclarationHelper(signature, kind, context)), + symbolToEntityName: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToName(symbol, context, meaning, /*expectsIdentifier*/ false)), + symbolToExpression: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToExpression(symbol, context, meaning)), + symbolToTypeParameterDeclarations: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParametersToTypeParameterDeclarations(symbol, context)), + symbolToParameterDeclaration: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToParameterDeclaration(symbol, context)), + typeParameterToDeclaration: (parameter: TypeParameter, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParameterToDeclaration(parameter, context)), + symbolTableToDeclarationStatements: (symbolTable: SymbolTable, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolTableToDeclarationStatements(symbolTable, context)), + symbolToNode: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToNode(symbol, context, meaning)), + }; + + function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes?: false): Type; + function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes: true): Type | undefined; + function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes?: boolean): Type | undefined { + const type = getTypeFromTypeNodeWithoutContext(node); + if (!context.mapper) return type; + + const mappedType = instantiateType(type, context.mapper); + return noMappedTypes && mappedType !== type ? undefined : mappedType; + } + + /** + * Unlike the utilities `setTextRange`, this checks if the `location` we're trying to set on `range` is within the + * same file as the active context. If not, the range is not applied. This prevents us from copying ranges across files, + * which will confuse the node printer (as it assumes all node ranges are within the current file). + * Additionally, if `range` _isn't synthetic_, or isn't in the current file, it will _copy_ it to _remove_ its' position + * information. + * + * It also calls `setOriginalNode` to setup a `.original` pointer, since you basically *always* want these in the node builder. + */ + function setTextRange(context: NodeBuilderContext, range: T, location: Node | undefined): T { + if (!nodeIsSynthesized(range) || !(range.flags & NodeFlags.Synthesized) || !context.enclosingFile || context.enclosingFile !== getSourceFileOfNode(getOriginalNode(range))) { + range = factory.cloneNode(range); // if `range` is synthesized or originates in another file, copy it so it definitely has synthetic positions + } + if (range === location) return range; + if (!location) { + return range; + } + if (!context.enclosingFile || context.enclosingFile !== getSourceFileOfNode(getOriginalNode(location))) { + return setOriginalNode(range, location); // if `location` is from another file, only set/update original pointer, and not positions, since copying text across files isn't supported by the emitter + } + return setTextRangeWorker(setOriginalNode(range, location), location); + } + + /** + * Same as expressionOrTypeToTypeNodeHelper, but also checks if the expression can be syntactically typed. + */ + function expressionOrTypeToTypeNode(context: NodeBuilderContext, expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean) { + const oldFlags = context.flags; + if (expr && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) { + syntacticNodeBuilder.serializeTypeOfExpression(expr, context, addUndefined); + } + context.flags |= NodeBuilderFlags.NoSyntacticPrinter; + const result = expressionOrTypeToTypeNodeHelper(context, expr, type, addUndefined); + context.flags = oldFlags; + return result; + } + function expressionOrTypeToTypeNodeHelper(context: NodeBuilderContext, expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean) { + if (expr) { + const typeNode = isAssertionExpression(expr) ? expr.type + : isJSDocTypeAssertion(expr) ? getJSDocTypeAssertionType(expr) + : undefined; + if (typeNode && !isConstTypeReference(typeNode)) { + const result = tryReuseExistingTypeNode(context, typeNode, type, expr.parent, addUndefined); + if (result) { + return result; + } + } + } + + if (addUndefined) { + type = getOptionalType(type); + } + + return typeToTypeNodeHelper(type, context); + } + + function tryReuseExistingTypeNode( + context: NodeBuilderContext, + typeNode: TypeNode, + type: Type, + host: Node, + addUndefined?: boolean, + ) { + const originalType = type; + if (addUndefined) { + type = getOptionalType(type); + } + const clone = tryReuseExistingNonParameterTypeNode(context, typeNode, type, host); + if (clone) { + if (addUndefined && !someType(getTypeFromTypeNode(context, typeNode), t => !!(t.flags & TypeFlags.Undefined))) { + return factory.createUnionTypeNode([clone, factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); + } + return clone; + } + if (addUndefined && originalType !== type) { + const cloneMissingUndefined = tryReuseExistingNonParameterTypeNode(context, typeNode, originalType, host); + if (cloneMissingUndefined) { + return factory.createUnionTypeNode([cloneMissingUndefined, factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); + } + } + return undefined; + } + + function tryReuseExistingNonParameterTypeNode( + context: NodeBuilderContext, + existing: TypeNode, + type: Type, + host = context.enclosingDeclaration, + annotationType = getTypeFromTypeNode(context, existing, /*noMappedTypes*/ true), + ) { + if (annotationType && typeNodeIsEquivalentToType(host, type, annotationType) && existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing, type)) { + const result = tryReuseExistingTypeNodeHelper(context, existing); + if (result) { + return result; + } + } + return undefined; + } + + function symbolToNode(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags) { + if (context.flags & NodeBuilderFlags.WriteComputedProps) { + if (symbol.valueDeclaration) { + const name = getNameOfDeclaration(symbol.valueDeclaration); + if (name && isComputedPropertyName(name)) return name; + } + const nameType = getSymbolLinks(symbol).nameType; + if (nameType && nameType.flags & (TypeFlags.EnumLiteral | TypeFlags.UniqueESSymbol)) { + context.enclosingDeclaration = nameType.symbol.valueDeclaration; + return factory.createComputedPropertyName(symbolToExpression(nameType.symbol, context, meaning)); + } + } + return symbolToExpression(symbol, context, meaning); + } + + function withContext(enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, tracker: SymbolTracker | undefined, cb: (context: NodeBuilderContext) => T): T | undefined { + const moduleResolverHost = tracker?.trackSymbol ? tracker.moduleResolverHost : + flags! & NodeBuilderFlags.DoNotIncludeSymbolChain ? createBasicNodeBuilderModuleSpecifierResolutionHost(host) : + undefined; + const context: NodeBuilderContext = { + enclosingDeclaration, + enclosingFile: enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration), + flags: flags || NodeBuilderFlags.None, + tracker: undefined!, + encounteredError: false, + reportedDiagnostic: false, + visitedTypes: undefined, + symbolDepth: undefined, + inferTypeParameters: undefined, + approximateLength: 0, + trackedSymbols: undefined, + bundled: !!compilerOptions.outFile && !!enclosingDeclaration && isExternalOrCommonJsModule(getSourceFileOfNode(enclosingDeclaration)), + truncating: false, + usedSymbolNames: undefined, + remappedSymbolNames: undefined, + remappedSymbolReferences: undefined, + reverseMappedStack: undefined, + mustCreateTypeParameterSymbolList: true, + typeParameterSymbolList: undefined, + mustCreateTypeParametersNamesLookups: true, + typeParameterNames: undefined, + typeParameterNamesByText: undefined, + typeParameterNamesByTextNextNameCount: undefined, + mapper: undefined, + }; + context.tracker = new SymbolTrackerImpl(context, tracker, moduleResolverHost); + const resultingNode = cb(context); + if (context.truncating && context.flags & NodeBuilderFlags.NoTruncation) { + context.tracker.reportTruncationError(); + } + return context.encounteredError ? undefined : resultingNode; + } + + function checkTruncationLength(context: NodeBuilderContext): boolean { + if (context.truncating) return context.truncating; + return context.truncating = context.approximateLength > ((context.flags & NodeBuilderFlags.NoTruncation) ? noTruncationMaximumTruncationLength : defaultMaximumTruncationLength); + } + + function typeToTypeNodeHelper(type: Type, context: NodeBuilderContext): TypeNode { + const savedFlags = context.flags; + const typeNode = typeToTypeNodeWorker(type, context); + context.flags = savedFlags; + return typeNode; + } + + function typeToTypeNodeWorker(type: Type, context: NodeBuilderContext): TypeNode { + if (cancellationToken && cancellationToken.throwIfCancellationRequested) { + cancellationToken.throwIfCancellationRequested(); + } + const inTypeAlias = context.flags & NodeBuilderFlags.InTypeAlias; + context.flags &= ~NodeBuilderFlags.InTypeAlias; + + if (!type) { + if (!(context.flags & NodeBuilderFlags.AllowEmptyUnionOrIntersection)) { + context.encounteredError = true; + return undefined!; // TODO: GH#18217 + } + context.approximateLength += 3; + return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + + if (!(context.flags & NodeBuilderFlags.NoTypeReduction)) { + type = getReducedType(type); + } + + if (type.flags & TypeFlags.Any) { + if (type.aliasSymbol) { + return factory.createTypeReferenceNode(symbolToEntityNameNode(type.aliasSymbol), mapToTypeNodes(type.aliasTypeArguments, context)); + } + if (type === unresolvedType) { + return addSyntheticLeadingComment(factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), SyntaxKind.MultiLineCommentTrivia, "unresolved"); + } + context.approximateLength += 3; + return factory.createKeywordTypeNode(type === intrinsicMarkerType ? SyntaxKind.IntrinsicKeyword : SyntaxKind.AnyKeyword); + } + if (type.flags & TypeFlags.Unknown) { + return factory.createKeywordTypeNode(SyntaxKind.UnknownKeyword); + } + if (type.flags & TypeFlags.String) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.StringKeyword); + } + if (type.flags & TypeFlags.Number) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.NumberKeyword); + } + if (type.flags & TypeFlags.BigInt) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.BigIntKeyword); + } + if (type.flags & TypeFlags.Boolean && !type.aliasSymbol) { + context.approximateLength += 7; + return factory.createKeywordTypeNode(SyntaxKind.BooleanKeyword); + } + if (type.flags & TypeFlags.EnumLike) { + if (type.symbol.flags & SymbolFlags.EnumMember) { + const parentSymbol = getParentOfSymbol(type.symbol)!; + const parentName = symbolToTypeNode(parentSymbol, context, SymbolFlags.Type); + if (getDeclaredTypeOfSymbol(parentSymbol) === type) { + return parentName; + } + const memberName = symbolName(type.symbol); + if (isIdentifierText(memberName, ScriptTarget.ES5)) { + return appendReferenceToType( + parentName as TypeReferenceNode | ImportTypeNode, + factory.createTypeReferenceNode(memberName, /*typeArguments*/ undefined), + ); + } + if (isImportTypeNode(parentName)) { + (parentName as any).isTypeOf = true; // mutably update, node is freshly manufactured anyhow + return factory.createIndexedAccessTypeNode(parentName, factory.createLiteralTypeNode(factory.createStringLiteral(memberName))); + } + else if (isTypeReferenceNode(parentName)) { + return factory.createIndexedAccessTypeNode(factory.createTypeQueryNode(parentName.typeName), factory.createLiteralTypeNode(factory.createStringLiteral(memberName))); + } + else { + return Debug.fail("Unhandled type node kind returned from `symbolToTypeNode`."); + } + } + return symbolToTypeNode(type.symbol, context, SymbolFlags.Type); + } + if (type.flags & TypeFlags.StringLiteral) { + context.approximateLength += (type as StringLiteralType).value.length + 2; + return factory.createLiteralTypeNode(setEmitFlags(factory.createStringLiteral((type as StringLiteralType).value, !!(context.flags & NodeBuilderFlags.UseSingleQuotesForStringLiteralType)), EmitFlags.NoAsciiEscaping)); + } + if (type.flags & TypeFlags.NumberLiteral) { + const value = (type as NumberLiteralType).value; + context.approximateLength += ("" + value).length; + return factory.createLiteralTypeNode(value < 0 ? factory.createPrefixUnaryExpression(SyntaxKind.MinusToken, factory.createNumericLiteral(-value)) : factory.createNumericLiteral(value)); + } + if (type.flags & TypeFlags.BigIntLiteral) { + context.approximateLength += (pseudoBigIntToString((type as BigIntLiteralType).value).length) + 1; + return factory.createLiteralTypeNode(factory.createBigIntLiteral((type as BigIntLiteralType).value)); + } + if (type.flags & TypeFlags.BooleanLiteral) { + context.approximateLength += (type as IntrinsicType).intrinsicName.length; + return factory.createLiteralTypeNode((type as IntrinsicType).intrinsicName === "true" ? factory.createTrue() : factory.createFalse()); + } + if (type.flags & TypeFlags.UniqueESSymbol) { + if (!(context.flags & NodeBuilderFlags.AllowUniqueESSymbolType)) { + if (isValueSymbolAccessible(type.symbol, context.enclosingDeclaration)) { + context.approximateLength += 6; + return symbolToTypeNode(type.symbol, context, SymbolFlags.Value); + } + if (context.tracker.reportInaccessibleUniqueSymbolError) { + context.tracker.reportInaccessibleUniqueSymbolError(); + } + } + context.approximateLength += 13; + return factory.createTypeOperatorNode(SyntaxKind.UniqueKeyword, factory.createKeywordTypeNode(SyntaxKind.SymbolKeyword)); + } + if (type.flags & TypeFlags.Void) { + context.approximateLength += 4; + return factory.createKeywordTypeNode(SyntaxKind.VoidKeyword); + } + if (type.flags & TypeFlags.Undefined) { + context.approximateLength += 9; + return factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword); + } + if (type.flags & TypeFlags.Null) { + context.approximateLength += 4; + return factory.createLiteralTypeNode(factory.createNull()); + } + if (type.flags & TypeFlags.Never) { + context.approximateLength += 5; + return factory.createKeywordTypeNode(SyntaxKind.NeverKeyword); + } + if (type.flags & TypeFlags.ESSymbol) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.SymbolKeyword); + } + if (type.flags & TypeFlags.NonPrimitive) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.ObjectKeyword); + } + if (isThisTypeParameter(type)) { + if (context.flags & NodeBuilderFlags.InObjectTypeLiteral) { + if (!context.encounteredError && !(context.flags & NodeBuilderFlags.AllowThisInObjectLiteral)) { + context.encounteredError = true; + } + context.tracker.reportInaccessibleThisError?.(); + } + context.approximateLength += 4; + return factory.createThisTypeNode(); + } + + if (!inTypeAlias && type.aliasSymbol && (context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope || isTypeSymbolAccessible(type.aliasSymbol, context.enclosingDeclaration))) { + const typeArgumentNodes = mapToTypeNodes(type.aliasTypeArguments, context); + if (isReservedMemberName(type.aliasSymbol.escapedName) && !(type.aliasSymbol.flags & SymbolFlags.Class)) return factory.createTypeReferenceNode(factory.createIdentifier(""), typeArgumentNodes); + if (length(typeArgumentNodes) === 1 && type.aliasSymbol === globalArrayType.symbol) { + return factory.createArrayTypeNode(typeArgumentNodes![0]); + } + return symbolToTypeNode(type.aliasSymbol, context, SymbolFlags.Type, typeArgumentNodes); + } + + const objectFlags = getObjectFlags(type); + + if (objectFlags & ObjectFlags.Reference) { + Debug.assert(!!(type.flags & TypeFlags.Object)); + return (type as TypeReference).node ? visitAndTransformType(type as TypeReference, typeReferenceToTypeNode) : typeReferenceToTypeNode(type as TypeReference); + } + if (type.flags & TypeFlags.TypeParameter || objectFlags & ObjectFlags.ClassOrInterface) { + if (type.flags & TypeFlags.TypeParameter && contains(context.inferTypeParameters, type)) { + context.approximateLength += symbolName(type.symbol).length + 6; + let constraintNode: TypeNode | undefined; + const constraint = getConstraintOfTypeParameter(type as TypeParameter); + if (constraint) { + // If the infer type has a constraint that is not the same as the constraint + // we would have normally inferred based on context, we emit the constraint + // using `infer T extends ?`. We omit inferred constraints from type references + // as they may be elided. + const inferredConstraint = getInferredTypeParameterConstraint(type as TypeParameter, /*omitTypeReferences*/ true); + if (!(inferredConstraint && isTypeIdenticalTo(constraint, inferredConstraint))) { + context.approximateLength += 9; + constraintNode = constraint && typeToTypeNodeHelper(constraint, context); + } + } + return factory.createInferTypeNode(typeParameterToDeclarationWithConstraint(type as TypeParameter, context, constraintNode)); + } + if ( + context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && + type.flags & TypeFlags.TypeParameter + ) { + const name = typeParameterToName(type, context); + context.approximateLength += idText(name).length; + return factory.createTypeReferenceNode(factory.createIdentifier(idText(name)), /*typeArguments*/ undefined); + } + // Ignore constraint/default when creating a usage (as opposed to declaration) of a type parameter. + if (type.symbol) { + return symbolToTypeNode(type.symbol, context, SymbolFlags.Type); + } + const name = (type === markerSuperTypeForCheck || type === markerSubTypeForCheck) && varianceTypeParameter && varianceTypeParameter.symbol ? + (type === markerSubTypeForCheck ? "sub-" : "super-") + symbolName(varianceTypeParameter.symbol) : "?"; + return factory.createTypeReferenceNode(factory.createIdentifier(name), /*typeArguments*/ undefined); + } + if (type.flags & TypeFlags.Union && (type as UnionType).origin) { + type = (type as UnionType).origin!; + } + if (type.flags & (TypeFlags.Union | TypeFlags.Intersection)) { + const types = type.flags & TypeFlags.Union ? formatUnionTypes((type as UnionType).types) : (type as IntersectionType).types; + if (length(types) === 1) { + return typeToTypeNodeHelper(types[0], context); + } + const typeNodes = mapToTypeNodes(types, context, /*isBareList*/ true); + if (typeNodes && typeNodes.length > 0) { + return type.flags & TypeFlags.Union ? factory.createUnionTypeNode(typeNodes) : factory.createIntersectionTypeNode(typeNodes); + } + else { + if (!context.encounteredError && !(context.flags & NodeBuilderFlags.AllowEmptyUnionOrIntersection)) { + context.encounteredError = true; + } + return undefined!; // TODO: GH#18217 + } + } + if (objectFlags & (ObjectFlags.Anonymous | ObjectFlags.Mapped)) { + Debug.assert(!!(type.flags & TypeFlags.Object)); + // The type is an object literal type. + return createAnonymousTypeNode(type as ObjectType); + } + if (type.flags & TypeFlags.Index) { + const indexedType = (type as IndexType).type; + context.approximateLength += 6; + const indexTypeNode = typeToTypeNodeHelper(indexedType, context); + return factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, indexTypeNode); + } + if (type.flags & TypeFlags.TemplateLiteral) { + const texts = (type as TemplateLiteralType).texts; + const types = (type as TemplateLiteralType).types; + const templateHead = factory.createTemplateHead(texts[0]); + const templateSpans = factory.createNodeArray( + map(types, (t, i) => + factory.createTemplateLiteralTypeSpan( + typeToTypeNodeHelper(t, context), + (i < types.length - 1 ? factory.createTemplateMiddle : factory.createTemplateTail)(texts[i + 1]), + )), + ); + context.approximateLength += 2; + return factory.createTemplateLiteralType(templateHead, templateSpans); + } + if (type.flags & TypeFlags.StringMapping) { + const typeNode = typeToTypeNodeHelper((type as StringMappingType).type, context); + return symbolToTypeNode((type as StringMappingType).symbol, context, SymbolFlags.Type, [typeNode]); + } + if (type.flags & TypeFlags.IndexedAccess) { + const objectTypeNode = typeToTypeNodeHelper((type as IndexedAccessType).objectType, context); + const indexTypeNode = typeToTypeNodeHelper((type as IndexedAccessType).indexType, context); + context.approximateLength += 2; + return factory.createIndexedAccessTypeNode(objectTypeNode, indexTypeNode); + } + if (type.flags & TypeFlags.Conditional) { + return visitAndTransformType(type, type => conditionalTypeToTypeNode(type as ConditionalType)); + } + if (type.flags & TypeFlags.Substitution) { + const typeNode = typeToTypeNodeHelper((type as SubstitutionType).baseType, context); + const noInferSymbol = isNoInferType(type) && getGlobalTypeSymbol("NoInfer" as __String, /*reportErrors*/ false); + return noInferSymbol ? symbolToTypeNode(noInferSymbol, context, SymbolFlags.Type, [typeNode]) : typeNode; + } + + return Debug.fail("Should be unreachable."); + + function conditionalTypeToTypeNode(type: ConditionalType) { + const checkTypeNode = typeToTypeNodeHelper(type.checkType, context); + context.approximateLength += 15; + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && type.root.isDistributive && !(type.checkType.flags & TypeFlags.TypeParameter)) { + const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); + const name = typeParameterToName(newParam, context); + const newTypeVariable = factory.createTypeReferenceNode(name); + context.approximateLength += 37; // 15 each for two added conditionals, 7 for an added infer type + const newMapper = prependTypeMapping(type.root.checkType, newParam, type.mapper); + const saveInferTypeParameters = context.inferTypeParameters; + context.inferTypeParameters = type.root.inferTypeParameters; + const extendsTypeNode = typeToTypeNodeHelper(instantiateType(type.root.extendsType, newMapper), context); + context.inferTypeParameters = saveInferTypeParameters; + const trueTypeNode = typeToTypeNodeOrCircularityElision(instantiateType(getTypeFromTypeNode(context, type.root.node.trueType), newMapper)); + const falseTypeNode = typeToTypeNodeOrCircularityElision(instantiateType(getTypeFromTypeNode(context, type.root.node.falseType), newMapper)); + + // outermost conditional makes `T` a type parameter, allowing the inner conditionals to be distributive + // second conditional makes `T` have `T & checkType` substitution, so it is correctly usable as the checkType + // inner conditional runs the check the user provided on the check type (distributively) and returns the result + // checkType extends infer T ? T extends checkType ? T extends extendsType ? trueType : falseType : never : never; + // this is potentially simplifiable to + // checkType extends infer T ? T extends checkType & extendsType ? trueType : falseType : never; + // but that may confuse users who read the output more. + // On the other hand, + // checkType extends infer T extends checkType ? T extends extendsType ? trueType : falseType : never; + // may also work with `infer ... extends ...` in, but would produce declarations only compatible with the latest TS. + return factory.createConditionalTypeNode( + checkTypeNode, + factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable.typeName) as Identifier)), + factory.createConditionalTypeNode( + factory.createTypeReferenceNode(factory.cloneNode(name)), + typeToTypeNodeHelper(type.checkType, context), + factory.createConditionalTypeNode(newTypeVariable, extendsTypeNode, trueTypeNode, falseTypeNode), + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ), + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ); + } + const saveInferTypeParameters = context.inferTypeParameters; + context.inferTypeParameters = type.root.inferTypeParameters; + const extendsTypeNode = typeToTypeNodeHelper(type.extendsType, context); + context.inferTypeParameters = saveInferTypeParameters; + const trueTypeNode = typeToTypeNodeOrCircularityElision(getTrueTypeFromConditionalType(type)); + const falseTypeNode = typeToTypeNodeOrCircularityElision(getFalseTypeFromConditionalType(type)); + return factory.createConditionalTypeNode(checkTypeNode, extendsTypeNode, trueTypeNode, falseTypeNode); + } + + function typeToTypeNodeOrCircularityElision(type: Type) { + if (type.flags & TypeFlags.Union) { + if (context.visitedTypes?.has(getTypeId(type))) { + if (!(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier)) { + context.encounteredError = true; + context.tracker?.reportCyclicStructureError?.(); + } + return createElidedInformationPlaceholder(context); + } + return visitAndTransformType(type, type => typeToTypeNodeHelper(type, context)); + } + return typeToTypeNodeHelper(type, context); + } + + function isMappedTypeHomomorphic(type: MappedType) { + return !!getHomomorphicTypeVariable(type); + } + + function isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type: MappedType) { + return !!type.target && isMappedTypeHomomorphic(type.target as MappedType) && !isMappedTypeHomomorphic(type); + } + + function createMappedTypeNodeFromType(type: MappedType) { + Debug.assert(!!(type.flags & TypeFlags.Object)); + const readonlyToken = type.declaration.readonlyToken ? factory.createToken(type.declaration.readonlyToken.kind) as ReadonlyKeyword | PlusToken | MinusToken : undefined; + const questionToken = type.declaration.questionToken ? factory.createToken(type.declaration.questionToken.kind) as QuestionToken | PlusToken | MinusToken : undefined; + let appropriateConstraintTypeNode: TypeNode; + let newTypeVariable: TypeReferenceNode | undefined; + // If the mapped type isn't `keyof` constraint-declared, _but_ still has modifiers preserved, and its naive instantiation won't preserve modifiers because its constraint isn't `keyof` constrained, we have work to do + const needsModifierPreservingWrapper = !isMappedTypeWithKeyofConstraintDeclaration(type) + && !(getModifiersTypeFromMappedType(type).flags & TypeFlags.Unknown) + && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams + && !(getConstraintTypeFromMappedType(type).flags & TypeFlags.TypeParameter && getConstraintOfTypeParameter(getConstraintTypeFromMappedType(type))?.flags! & TypeFlags.Index); + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // We have a { [P in keyof T]: X } + // We do this to ensure we retain the toplevel keyof-ness of the type which may be lost due to keyof distribution during `getConstraintTypeFromMappedType` + if (isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type) && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { + const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); + const name = typeParameterToName(newParam, context); + newTypeVariable = factory.createTypeReferenceNode(name); + } + appropriateConstraintTypeNode = factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, newTypeVariable || typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context)); + } + else if (needsModifierPreservingWrapper) { + // So, step 1: new type variable + const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); + const name = typeParameterToName(newParam, context); + newTypeVariable = factory.createTypeReferenceNode(name); + // step 2: make that new type variable itself the constraint node, making the mapped type `{[K in T_1]: Template}` + appropriateConstraintTypeNode = newTypeVariable; + } + else { + appropriateConstraintTypeNode = typeToTypeNodeHelper(getConstraintTypeFromMappedType(type), context); + } + const typeParameterNode = typeParameterToDeclarationWithConstraint(getTypeParameterFromMappedType(type), context, appropriateConstraintTypeNode); + const nameTypeNode = type.declaration.nameType ? typeToTypeNodeHelper(getNameTypeFromMappedType(type)!, context) : undefined; + const templateTypeNode = typeToTypeNodeHelper(removeMissingType(getTemplateTypeFromMappedType(type), !!(getMappedTypeModifiers(type) & MappedTypeModifiers.IncludeOptional)), context); + const mappedTypeNode = factory.createMappedTypeNode(readonlyToken, typeParameterNode, nameTypeNode, questionToken, templateTypeNode, /*members*/ undefined); + context.approximateLength += 10; + const result = setEmitFlags(mappedTypeNode, EmitFlags.SingleLine); + if (isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type) && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { + // homomorphic mapped type with a non-homomorphic naive inlining + // wrap it with a conditional like `SomeModifiersType extends infer U ? {..the mapped type...} : never` to ensure the resulting + // type stays homomorphic + const originalConstraint = instantiateType(getConstraintOfTypeParameter(getTypeFromTypeNode(context, (type.declaration.typeParameter.constraint! as TypeOperatorNode).type) as TypeParameter) || unknownType, type.mapper); + return factory.createConditionalTypeNode( + typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context), + factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable!.typeName) as Identifier, originalConstraint.flags & TypeFlags.Unknown ? undefined : typeToTypeNodeHelper(originalConstraint, context))), + result, + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ); + } + else if (needsModifierPreservingWrapper) { + // and step 3: once the mapped type is reconstructed, create a `ConstraintType extends infer T_1 extends keyof ModifiersType ? {[K in T_1]: Template} : never` + // subtly different from the `keyof` constraint case, by including the `keyof` constraint on the `infer` type parameter, it doesn't rely on the constraint type being itself + // constrained to a `keyof` type to preserve its modifier-preserving behavior. This is all basically because we preserve modifiers for a wider set of mapped types than + // just homomorphic ones. + return factory.createConditionalTypeNode( + typeToTypeNodeHelper(getConstraintTypeFromMappedType(type), context), + factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable!.typeName) as Identifier, factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context)))), + result, + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ); + } + return result; + } + + function createAnonymousTypeNode(type: ObjectType): TypeNode { + const typeId = type.id; + const symbol = type.symbol; + if (symbol) { + const isInstantiationExpressionType = !!(getObjectFlags(type) & ObjectFlags.InstantiationExpressionType); + if (isInstantiationExpressionType) { + const instantiationExpressionType = type as InstantiationExpressionType; + const existing = instantiationExpressionType.node; + if (isTypeQueryNode(existing)) { + const typeNode = tryReuseExistingNonParameterTypeNode(context, existing, type); + if (typeNode) { + return typeNode; + } + } + if (context.visitedTypes?.has(typeId)) { + return createElidedInformationPlaceholder(context); + } + return visitAndTransformType(type, createTypeNodeFromObjectType); + } + const isInstanceType = isClassInstanceSide(type) ? SymbolFlags.Type : SymbolFlags.Value; + if (isJSConstructor(symbol.valueDeclaration)) { + // Instance and static types share the same symbol; only add 'typeof' for the static side. + return symbolToTypeNode(symbol, context, isInstanceType); + } + // Always use 'typeof T' for type of class, enum, and module objects + else if ( + symbol.flags & SymbolFlags.Class + && !getBaseTypeVariableOfClass(symbol) + && !(symbol.valueDeclaration && isClassLike(symbol.valueDeclaration) && context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral && (!isClassDeclaration(symbol.valueDeclaration) || isSymbolAccessible(symbol, context.enclosingDeclaration, isInstanceType, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible)) || + symbol.flags & (SymbolFlags.Enum | SymbolFlags.ValueModule) || + shouldWriteTypeOfFunctionSymbol() + ) { + return symbolToTypeNode(symbol, context, isInstanceType); + } + else if (context.visitedTypes?.has(typeId)) { + // If type is an anonymous type literal in a type alias declaration, use type alias name + const typeAlias = getTypeAliasForTypeLiteral(type); + if (typeAlias) { + // The specified symbol flags need to be reinterpreted as type flags + return symbolToTypeNode(typeAlias, context, SymbolFlags.Type); + } + else { + return createElidedInformationPlaceholder(context); + } + } + else { + return visitAndTransformType(type, createTypeNodeFromObjectType); + } + } + else { + // Anonymous types without a symbol are never circular. + return createTypeNodeFromObjectType(type); + } + function shouldWriteTypeOfFunctionSymbol() { + const isStaticMethodSymbol = !!(symbol.flags & SymbolFlags.Method) && // typeof static method + some(symbol.declarations, declaration => isStatic(declaration)); + const isNonLocalFunctionSymbol = !!(symbol.flags & SymbolFlags.Function) && + (symbol.parent || // is exported function symbol + forEach(symbol.declarations, declaration => declaration.parent.kind === SyntaxKind.SourceFile || declaration.parent.kind === SyntaxKind.ModuleBlock)); + if (isStaticMethodSymbol || isNonLocalFunctionSymbol) { + // typeof is allowed only for static/non local functions + return (!!(context.flags & NodeBuilderFlags.UseTypeOfFunction) || (context.visitedTypes?.has(typeId))) && // it is type of the symbol uses itself recursively + (!(context.flags & NodeBuilderFlags.UseStructuralFallback) || isValueSymbolAccessible(symbol, context.enclosingDeclaration)); // And the build is going to succeed without visibility error or there is no structural fallback allowed + } + } + } + + function visitAndTransformType(type: T, transform: (type: T) => TypeNode) { + const typeId = type.id; + const isConstructorObject = getObjectFlags(type) & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & SymbolFlags.Class; + const id = getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference & T).node ? "N" + getNodeId((type as TypeReference & T).node!) : + type.flags & TypeFlags.Conditional ? "N" + getNodeId((type as ConditionalType & T).root.node) : + type.symbol ? (isConstructorObject ? "+" : "") + getSymbolId(type.symbol) : + undefined; + // Since instantiations of the same anonymous type have the same symbol, tracking symbols instead + // of types allows us to catch circular references to instantiations of the same anonymous type + if (!context.visitedTypes) { + context.visitedTypes = new Set(); + } + if (id && !context.symbolDepth) { + context.symbolDepth = new Map(); + } + + const links = context.enclosingDeclaration && getNodeLinks(context.enclosingDeclaration); + const key = `${getTypeId(type)}|${context.flags}`; + if (links) { + links.serializedTypes ||= new Map(); + } + const cachedResult = links?.serializedTypes?.get(key); + if (cachedResult) { + // TODO:: check if we instead store late painted statements associated with this? + cachedResult.trackedSymbols?.forEach( + ([symbol, enclosingDeclaration, meaning]) => + context.tracker.trackSymbol( + symbol, + enclosingDeclaration, + meaning, + ), + ); + if (cachedResult.truncating) { + context.truncating = true; + } + context.approximateLength += cachedResult.addedLength; + return deepCloneOrReuseNode(cachedResult.node); + } + + let depth: number | undefined; + if (id) { + depth = context.symbolDepth!.get(id) || 0; + if (depth > 10) { + return createElidedInformationPlaceholder(context); + } + context.symbolDepth!.set(id, depth + 1); + } + context.visitedTypes.add(typeId); + const prevTrackedSymbols = context.trackedSymbols; + context.trackedSymbols = undefined; + const startLength = context.approximateLength; + const result = transform(type); + const addedLength = context.approximateLength - startLength; + if (!context.reportedDiagnostic && !context.encounteredError) { + links?.serializedTypes?.set(key, { + node: result, + truncating: context.truncating, + addedLength, + trackedSymbols: context.trackedSymbols, + }); + } + context.visitedTypes.delete(typeId); + if (id) { + context.symbolDepth!.set(id, depth!); + } + context.trackedSymbols = prevTrackedSymbols; + return result; + + function deepCloneOrReuseNode(node: T): T { + if (!nodeIsSynthesized(node) && getParseTreeNode(node) === node) { + return node; + } + return setTextRange(context, factory.cloneNode(visitEachChildWorker(node, deepCloneOrReuseNode, /*context*/ undefined, deepCloneOrReuseNodes, deepCloneOrReuseNode)), node); + } + + function deepCloneOrReuseNodes( + nodes: NodeArray | undefined, + visitor: Visitor, + test?: (node: Node) => boolean, + start?: number, + count?: number, + ): NodeArray | undefined { + if (nodes && nodes.length === 0) { + // Ensure we explicitly make a copy of an empty array; visitNodes will not do this unless the array has elements, + // which can lead to us reusing the same empty NodeArray more than once within the same AST during type noding. + return setTextRangeWorker(factory.createNodeArray(/*elements*/ undefined, nodes.hasTrailingComma), nodes); + } + return visitNodes(nodes, visitor, test, start, count); + } + } + + function createTypeNodeFromObjectType(type: ObjectType): TypeNode { + if (isGenericMappedType(type) || (type as MappedType).containsError) { + return createMappedTypeNodeFromType(type as MappedType); + } + + const resolved = resolveStructuredTypeMembers(type); + if (!resolved.properties.length && !resolved.indexInfos.length) { + if (!resolved.callSignatures.length && !resolved.constructSignatures.length) { + context.approximateLength += 2; + return setEmitFlags(factory.createTypeLiteralNode(/*members*/ undefined), EmitFlags.SingleLine); + } + + if (resolved.callSignatures.length === 1 && !resolved.constructSignatures.length) { + const signature = resolved.callSignatures[0]; + const signatureNode = signatureToSignatureDeclarationHelper(signature, SyntaxKind.FunctionType, context) as FunctionTypeNode; + return signatureNode; + } + + if (resolved.constructSignatures.length === 1 && !resolved.callSignatures.length) { + const signature = resolved.constructSignatures[0]; + const signatureNode = signatureToSignatureDeclarationHelper(signature, SyntaxKind.ConstructorType, context) as ConstructorTypeNode; + return signatureNode; + } + } + + const abstractSignatures = filter(resolved.constructSignatures, signature => !!(signature.flags & SignatureFlags.Abstract)); + if (some(abstractSignatures)) { + const types = map(abstractSignatures, s => getOrCreateTypeFromSignature(s)); + // count the number of type elements excluding abstract constructors + const typeElementCount = resolved.callSignatures.length + + (resolved.constructSignatures.length - abstractSignatures.length) + + resolved.indexInfos.length + + // exclude `prototype` when writing a class expression as a type literal, as per + // the logic in `createTypeNodesFromResolvedType`. + (context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral ? + countWhere(resolved.properties, p => !(p.flags & SymbolFlags.Prototype)) : + length(resolved.properties)); + // don't include an empty object literal if there were no other static-side + // properties to write, i.e. `abstract class C { }` becomes `abstract new () => {}` + // and not `(abstract new () => {}) & {}` + if (typeElementCount) { + // create a copy of the object type without any abstract construct signatures. + types.push(getResolvedTypeWithoutAbstractConstructSignatures(resolved)); + } + return typeToTypeNodeHelper(getIntersectionType(types), context); + } + + const savedFlags = context.flags; + context.flags |= NodeBuilderFlags.InObjectTypeLiteral; + const members = createTypeNodesFromResolvedType(resolved); + context.flags = savedFlags; + const typeLiteralNode = factory.createTypeLiteralNode(members); + context.approximateLength += 2; + setEmitFlags(typeLiteralNode, (context.flags & NodeBuilderFlags.MultilineObjectLiterals) ? 0 : EmitFlags.SingleLine); + return typeLiteralNode; + } + + function typeReferenceToTypeNode(type: TypeReference) { + let typeArguments: readonly Type[] = getTypeArguments(type); + if (type.target === globalArrayType || type.target === globalReadonlyArrayType) { + if (context.flags & NodeBuilderFlags.WriteArrayAsGenericType) { + const typeArgumentNode = typeToTypeNodeHelper(typeArguments[0], context); + return factory.createTypeReferenceNode(type.target === globalArrayType ? "Array" : "ReadonlyArray", [typeArgumentNode]); + } + const elementType = typeToTypeNodeHelper(typeArguments[0], context); + const arrayType = factory.createArrayTypeNode(elementType); + return type.target === globalArrayType ? arrayType : factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, arrayType); + } + else if (type.target.objectFlags & ObjectFlags.Tuple) { + typeArguments = sameMap(typeArguments, (t, i) => removeMissingType(t, !!((type.target as TupleType).elementFlags[i] & ElementFlags.Optional))); + if (typeArguments.length > 0) { + const arity = getTypeReferenceArity(type); + const tupleConstituentNodes = mapToTypeNodes(typeArguments.slice(0, arity), context); + if (tupleConstituentNodes) { + const { labeledElementDeclarations } = type.target as TupleType; + for (let i = 0; i < tupleConstituentNodes.length; i++) { + const flags = (type.target as TupleType).elementFlags[i]; + const labeledElementDeclaration = labeledElementDeclarations?.[i]; + + if (labeledElementDeclaration) { + tupleConstituentNodes[i] = factory.createNamedTupleMember( + flags & ElementFlags.Variable ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined, + factory.createIdentifier(unescapeLeadingUnderscores(getTupleElementLabel(labeledElementDeclaration))), + flags & ElementFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + flags & ElementFlags.Rest ? factory.createArrayTypeNode(tupleConstituentNodes[i]) : + tupleConstituentNodes[i], + ); + } + else { + tupleConstituentNodes[i] = flags & ElementFlags.Variable ? factory.createRestTypeNode(flags & ElementFlags.Rest ? factory.createArrayTypeNode(tupleConstituentNodes[i]) : tupleConstituentNodes[i]) : + flags & ElementFlags.Optional ? factory.createOptionalTypeNode(tupleConstituentNodes[i]) : + tupleConstituentNodes[i]; + } + } + const tupleTypeNode = setEmitFlags(factory.createTupleTypeNode(tupleConstituentNodes), EmitFlags.SingleLine); + return (type.target as TupleType).readonly ? factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, tupleTypeNode) : tupleTypeNode; + } + } + if (context.encounteredError || (context.flags & NodeBuilderFlags.AllowEmptyTuple)) { + const tupleTypeNode = setEmitFlags(factory.createTupleTypeNode([]), EmitFlags.SingleLine); + return (type.target as TupleType).readonly ? factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, tupleTypeNode) : tupleTypeNode; + } + context.encounteredError = true; + return undefined!; // TODO: GH#18217 + } + else if ( + context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral && + type.symbol.valueDeclaration && + isClassLike(type.symbol.valueDeclaration) && + !isValueSymbolAccessible(type.symbol, context.enclosingDeclaration) + ) { + return createAnonymousTypeNode(type); + } + else { + const outerTypeParameters = type.target.outerTypeParameters; + let i = 0; + let resultType: TypeReferenceNode | ImportTypeNode | undefined; + if (outerTypeParameters) { + const length = outerTypeParameters.length; + while (i < length) { + // Find group of type arguments for type parameters with the same declaring container. + const start = i; + const parent = getParentSymbolOfTypeParameter(outerTypeParameters[i])!; + do { + i++; + } + while (i < length && getParentSymbolOfTypeParameter(outerTypeParameters[i]) === parent); + // When type parameters are their own type arguments for the whole group (i.e. we have + // the default outer type arguments), we don't show the group. + if (!rangeEquals(outerTypeParameters, typeArguments, start, i)) { + const typeArgumentSlice = mapToTypeNodes(typeArguments.slice(start, i), context); + const flags = context.flags; + context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences; + const ref = symbolToTypeNode(parent, context, SymbolFlags.Type, typeArgumentSlice) as TypeReferenceNode | ImportTypeNode; + context.flags = flags; + resultType = !resultType ? ref : appendReferenceToType(resultType, ref as TypeReferenceNode); + } + } + } + let typeArgumentNodes: readonly TypeNode[] | undefined; + if (typeArguments.length > 0) { + const typeParameterCount = (type.target.typeParameters || emptyArray).length; + typeArgumentNodes = mapToTypeNodes(typeArguments.slice(i, typeParameterCount), context); + } + const flags = context.flags; + context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences; + const finalRef = symbolToTypeNode(type.symbol, context, SymbolFlags.Type, typeArgumentNodes); + context.flags = flags; + return !resultType ? finalRef : appendReferenceToType(resultType, finalRef as TypeReferenceNode); + } + } + + function appendReferenceToType(root: TypeReferenceNode | ImportTypeNode, ref: TypeReferenceNode): TypeReferenceNode | ImportTypeNode { + if (isImportTypeNode(root)) { + // first shift type arguments + let typeArguments = root.typeArguments; + let qualifier = root.qualifier; + if (qualifier) { + if (isIdentifier(qualifier)) { + if (typeArguments !== getIdentifierTypeArguments(qualifier)) { + qualifier = setIdentifierTypeArguments(factory.cloneNode(qualifier), typeArguments); + } + } + else { + if (typeArguments !== getIdentifierTypeArguments(qualifier.right)) { + qualifier = factory.updateQualifiedName(qualifier, qualifier.left, setIdentifierTypeArguments(factory.cloneNode(qualifier.right), typeArguments)); + } + } + } + typeArguments = ref.typeArguments; + // then move qualifiers + const ids = getAccessStack(ref); + for (const id of ids) { + qualifier = qualifier ? factory.createQualifiedName(qualifier, id) : id; + } + return factory.updateImportTypeNode( + root, + root.argument, + root.attributes, + qualifier, + typeArguments, + root.isTypeOf, + ); + } + else { + // first shift type arguments + let typeArguments = root.typeArguments; + let typeName = root.typeName; + if (isIdentifier(typeName)) { + if (typeArguments !== getIdentifierTypeArguments(typeName)) { + typeName = setIdentifierTypeArguments(factory.cloneNode(typeName), typeArguments); + } + } + else { + if (typeArguments !== getIdentifierTypeArguments(typeName.right)) { + typeName = factory.updateQualifiedName(typeName, typeName.left, setIdentifierTypeArguments(factory.cloneNode(typeName.right), typeArguments)); + } + } + typeArguments = ref.typeArguments; + // then move qualifiers + const ids = getAccessStack(ref); + for (const id of ids) { + typeName = factory.createQualifiedName(typeName, id); + } + return factory.updateTypeReferenceNode( + root, + typeName, + typeArguments, + ); + } + } + + function getAccessStack(ref: TypeReferenceNode): Identifier[] { + let state = ref.typeName; + const ids = []; + while (!isIdentifier(state)) { + ids.unshift(state.right); + state = state.left; + } + ids.unshift(state); + return ids; + } + + function createTypeNodesFromResolvedType(resolvedType: ResolvedType): TypeElement[] | undefined { + if (checkTruncationLength(context)) { + return [factory.createPropertySignature(/*modifiers*/ undefined, "...", /*questionToken*/ undefined, /*type*/ undefined)]; + } + const typeElements: TypeElement[] = []; + for (const signature of resolvedType.callSignatures) { + typeElements.push(signatureToSignatureDeclarationHelper(signature, SyntaxKind.CallSignature, context) as CallSignatureDeclaration); + } + for (const signature of resolvedType.constructSignatures) { + if (signature.flags & SignatureFlags.Abstract) continue; + typeElements.push(signatureToSignatureDeclarationHelper(signature, SyntaxKind.ConstructSignature, context) as ConstructSignatureDeclaration); + } + for (const info of resolvedType.indexInfos) { + typeElements.push(indexInfoToIndexSignatureDeclarationHelper(info, context, resolvedType.objectFlags & ObjectFlags.ReverseMapped ? createElidedInformationPlaceholder(context) : undefined)); + } + + const properties = resolvedType.properties; + if (!properties) { + return typeElements; + } + + let i = 0; + for (const propertySymbol of properties) { + i++; + if (context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral) { + if (propertySymbol.flags & SymbolFlags.Prototype) { + continue; + } + if (getDeclarationModifierFlagsFromSymbol(propertySymbol) & (ModifierFlags.Private | ModifierFlags.Protected) && context.tracker.reportPrivateInBaseOfClassExpression) { + context.tracker.reportPrivateInBaseOfClassExpression(unescapeLeadingUnderscores(propertySymbol.escapedName)); + } + } + if (checkTruncationLength(context) && (i + 2 < properties.length - 1)) { + typeElements.push(factory.createPropertySignature(/*modifiers*/ undefined, `... ${properties.length - i} more ...`, /*questionToken*/ undefined, /*type*/ undefined)); + addPropertyToElementList(properties[properties.length - 1], context, typeElements); + break; + } + addPropertyToElementList(propertySymbol, context, typeElements); + } + return typeElements.length ? typeElements : undefined; + } + } + + function createElidedInformationPlaceholder(context: NodeBuilderContext) { + context.approximateLength += 3; + if (!(context.flags & NodeBuilderFlags.NoTruncation)) { + return factory.createTypeReferenceNode(factory.createIdentifier("..."), /*typeArguments*/ undefined); + } + return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + + function shouldUsePlaceholderForProperty(propertySymbol: Symbol, context: NodeBuilderContext) { + // Use placeholders for reverse mapped types we've either already descended into, or which + // are nested reverse mappings within a mapping over a non-anonymous type. The later is a restriction mostly just to + // reduce the blowup in printback size from doing, eg, a deep reverse mapping over `Window`. + // Since anonymous types usually come from expressions, this allows us to preserve the output + // for deep mappings which likely come from expressions, while truncating those parts which + // come from mappings over library functions. + return !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped) + && ( + contains(context.reverseMappedStack, propertySymbol as ReverseMappedSymbol) + || ( + context.reverseMappedStack?.[0] + && !(getObjectFlags(last(context.reverseMappedStack).links.propertyType) & ObjectFlags.Anonymous) + ) + ); + } + + function addPropertyToElementList(propertySymbol: Symbol, context: NodeBuilderContext, typeElements: TypeElement[]) { + const propertyIsReverseMapped = !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped); + const propertyType = shouldUsePlaceholderForProperty(propertySymbol, context) ? + anyType : getNonMissingTypeOfSymbol(propertySymbol); + const saveEnclosingDeclaration = context.enclosingDeclaration; + context.enclosingDeclaration = undefined; + if (context.tracker.canTrackSymbol && isLateBoundName(propertySymbol.escapedName)) { + if (propertySymbol.declarations) { + const decl = first(propertySymbol.declarations); + if (hasLateBindableName(decl)) { + if (isBinaryExpression(decl)) { + const name = getNameOfDeclaration(decl); + if (name && isElementAccessExpression(name) && isPropertyAccessEntityNameExpression(name.argumentExpression)) { + trackComputedName(name.argumentExpression, saveEnclosingDeclaration, context); + } + } + else { + trackComputedName(decl.name.expression, saveEnclosingDeclaration, context); + } + } + } + else { + context.tracker.reportNonSerializableProperty(symbolToString(propertySymbol)); + } + } + context.enclosingDeclaration = propertySymbol.valueDeclaration || propertySymbol.declarations?.[0] || saveEnclosingDeclaration; + const propertyName = getPropertyNameNodeForSymbol(propertySymbol, context); + context.enclosingDeclaration = saveEnclosingDeclaration; + context.approximateLength += symbolName(propertySymbol).length + 1; + + if (propertySymbol.flags & SymbolFlags.Accessor) { + const writeType = getWriteTypeOfSymbol(propertySymbol); + if (propertyType !== writeType && !isErrorType(propertyType) && !isErrorType(writeType)) { + const getterDeclaration = getDeclarationOfKind(propertySymbol, SyntaxKind.GetAccessor)!; + const getterSignature = getSignatureFromDeclaration(getterDeclaration); + typeElements.push( + setCommentRange( + context, + signatureToSignatureDeclarationHelper(getterSignature, SyntaxKind.GetAccessor, context, { name: propertyName }) as GetAccessorDeclaration, + getterDeclaration, + ), + ); + const setterDeclaration = getDeclarationOfKind(propertySymbol, SyntaxKind.SetAccessor)!; + const setterSignature = getSignatureFromDeclaration(setterDeclaration); + typeElements.push( + setCommentRange( + context, + signatureToSignatureDeclarationHelper(setterSignature, SyntaxKind.SetAccessor, context, { name: propertyName }) as SetAccessorDeclaration, + setterDeclaration, + ), + ); + return; + } + } + + const optionalToken = propertySymbol.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined; + if (propertySymbol.flags & (SymbolFlags.Function | SymbolFlags.Method) && !getPropertiesOfObjectType(propertyType).length && !isReadonlySymbol(propertySymbol)) { + const signatures = getSignaturesOfType(filterType(propertyType, t => !(t.flags & TypeFlags.Undefined)), SignatureKind.Call); + for (const signature of signatures) { + const methodDeclaration = signatureToSignatureDeclarationHelper(signature, SyntaxKind.MethodSignature, context, { name: propertyName, questionToken: optionalToken }) as MethodSignature; + typeElements.push(preserveCommentsOn(methodDeclaration)); + } + if (signatures.length || !optionalToken) { + return; + } + } + let propertyTypeNode: TypeNode; + if (shouldUsePlaceholderForProperty(propertySymbol, context)) { + propertyTypeNode = createElidedInformationPlaceholder(context); + } + else { + if (propertyIsReverseMapped) { + context.reverseMappedStack ||= []; + context.reverseMappedStack.push(propertySymbol as ReverseMappedSymbol); + } + propertyTypeNode = propertyType ? serializeTypeForDeclaration(context, /*declaration*/ undefined, propertyType, propertySymbol) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + if (propertyIsReverseMapped) { + context.reverseMappedStack!.pop(); + } + } + + const modifiers = isReadonlySymbol(propertySymbol) ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined; + if (modifiers) { + context.approximateLength += 9; + } + const propertySignature = factory.createPropertySignature( + modifiers, + propertyName, + optionalToken, + propertyTypeNode, + ); + + typeElements.push(preserveCommentsOn(propertySignature)); + + function preserveCommentsOn(node: T) { + const jsdocPropertyTag = propertySymbol.declarations?.find((d): d is JSDocPropertyTag => d.kind === SyntaxKind.JSDocPropertyTag); + if (jsdocPropertyTag) { + const commentText = getTextOfJSDocComment(jsdocPropertyTag.comment); + if (commentText) { + setSyntheticLeadingComments(node, [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }]); + } + } + else if (propertySymbol.valueDeclaration) { + // Copy comments to node for declaration emit + setCommentRange(context, node, propertySymbol.valueDeclaration); + } + return node; + } + } + + function setCommentRange(context: NodeBuilderContext, node: T, range: Node): T { + if (context.enclosingFile && context.enclosingFile === getSourceFileOfNode(range)) { + // Copy comments to node for declaration emit + return setCommentRangeWorker(node, range); + } + return node; + } + + function mapToTypeNodes(types: readonly Type[] | undefined, context: NodeBuilderContext, isBareList?: boolean): TypeNode[] | undefined { + if (some(types)) { + if (checkTruncationLength(context)) { + if (!isBareList) { + return [factory.createTypeReferenceNode("...", /*typeArguments*/ undefined)]; + } + else if (types.length > 2) { + return [ + typeToTypeNodeHelper(types[0], context), + factory.createTypeReferenceNode(`... ${types.length - 2} more ...`, /*typeArguments*/ undefined), + typeToTypeNodeHelper(types[types.length - 1], context), + ]; + } + } + const mayHaveNameCollisions = !(context.flags & NodeBuilderFlags.UseFullyQualifiedType); + /** Map from type reference identifier text to [type, index in `result` where the type node is] */ + const seenNames = mayHaveNameCollisions ? createMultiMap<__String, [Type, number]>() : undefined; + const result: TypeNode[] = []; + let i = 0; + for (const type of types) { + i++; + if (checkTruncationLength(context) && (i + 2 < types.length - 1)) { + result.push(factory.createTypeReferenceNode(`... ${types.length - i} more ...`, /*typeArguments*/ undefined)); + const typeNode = typeToTypeNodeHelper(types[types.length - 1], context); + if (typeNode) { + result.push(typeNode); + } + break; + } + context.approximateLength += 2; // Account for whitespace + separator + const typeNode = typeToTypeNodeHelper(type, context); + if (typeNode) { + result.push(typeNode); + if (seenNames && isIdentifierTypeReference(typeNode)) { + seenNames.add(typeNode.typeName.escapedText, [type, result.length - 1]); + } + } + } + + if (seenNames) { + // To avoid printing types like `[Foo, Foo]` or `Bar & Bar` where + // occurrences of the same name actually come from different + // namespaces, go through the single-identifier type reference nodes + // we just generated, and see if any names were generated more than + // once while referring to different types. If so, regenerate the + // type node for each entry by that name with the + // `UseFullyQualifiedType` flag enabled. + const saveContextFlags = context.flags; + context.flags |= NodeBuilderFlags.UseFullyQualifiedType; + seenNames.forEach(types => { + if (!arrayIsHomogeneous(types, ([a], [b]) => typesAreSameReference(a, b))) { + for (const [type, resultIndex] of types) { + result[resultIndex] = typeToTypeNodeHelper(type, context); + } + } + }); + context.flags = saveContextFlags; + } + + return result; + } + } + + function typesAreSameReference(a: Type, b: Type): boolean { + return a === b + || !!a.symbol && a.symbol === b.symbol + || !!a.aliasSymbol && a.aliasSymbol === b.aliasSymbol; + } + + function indexInfoToIndexSignatureDeclarationHelper(indexInfo: IndexInfo, context: NodeBuilderContext, typeNode: TypeNode | undefined): IndexSignatureDeclaration { + const name = getNameFromIndexInfo(indexInfo) || "x"; + const indexerTypeNode = typeToTypeNodeHelper(indexInfo.keyType, context); + + const indexingParameter = factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + name, + /*questionToken*/ undefined, + indexerTypeNode, + /*initializer*/ undefined, + ); + if (!typeNode) { + typeNode = typeToTypeNodeHelper(indexInfo.type || anyType, context); + } + if (!indexInfo.type && !(context.flags & NodeBuilderFlags.AllowEmptyIndexInfoType)) { + context.encounteredError = true; + } + context.approximateLength += name.length + 4; + return factory.createIndexSignature( + indexInfo.isReadonly ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined, + [indexingParameter], + typeNode, + ); + } + + interface SignatureToSignatureDeclarationOptions { + modifiers?: readonly Modifier[]; + name?: PropertyName; + questionToken?: QuestionToken; + } + + function signatureToSignatureDeclarationHelper(signature: Signature, kind: SignatureDeclaration["kind"], context: NodeBuilderContext, options?: SignatureToSignatureDeclarationOptions): SignatureDeclaration { + let typeParameters: TypeParameterDeclaration[] | undefined; + let typeArguments: TypeNode[] | undefined; + + const expandedParams = getExpandedParameters(signature, /*skipUnionExpanding*/ true)[0]; + const cleanup = enterNewScope(context, signature.declaration, expandedParams, signature.typeParameters, signature.parameters, signature.mapper); + context.approximateLength += 3; // Usually a signature contributes a few more characters than this, but 3 is the minimum + + if (context.flags & NodeBuilderFlags.WriteTypeArgumentsOfSignature && signature.target && signature.mapper && signature.target.typeParameters) { + typeArguments = signature.target.typeParameters.map(parameter => typeToTypeNodeHelper(instantiateType(parameter, signature.mapper), context)); + } + else { + typeParameters = signature.typeParameters && signature.typeParameters.map(parameter => typeParameterToDeclaration(parameter, context)); + } + + const flags = context.flags; + context.flags &= ~NodeBuilderFlags.SuppressAnyReturnType; // SuppressAnyReturnType should only apply to the signature `return` position + // If the expanded parameter list had a variadic in a non-trailing position, don't expand it + const parameters = (some(expandedParams, p => p !== expandedParams[expandedParams.length - 1] && !!(getCheckFlags(p) & CheckFlags.RestParameter)) ? signature.parameters : expandedParams).map(parameter => symbolToParameterDeclaration(parameter, context, kind === SyntaxKind.Constructor)); + const thisParameter = context.flags & NodeBuilderFlags.OmitThisParameter ? undefined : tryGetThisParameterDeclaration(signature, context); + if (thisParameter) { + parameters.unshift(thisParameter); + } + context.flags = flags; + + const returnTypeNode = serializeReturnTypeForSignature(context, signature); + + let modifiers = options?.modifiers; + if ((kind === SyntaxKind.ConstructorType) && signature.flags & SignatureFlags.Abstract) { + const flags = modifiersToFlags(modifiers); + modifiers = factory.createModifiersFromModifierFlags(flags | ModifierFlags.Abstract); + } + + const node = kind === SyntaxKind.CallSignature ? factory.createCallSignature(typeParameters, parameters, returnTypeNode) : + kind === SyntaxKind.ConstructSignature ? factory.createConstructSignature(typeParameters, parameters, returnTypeNode) : + kind === SyntaxKind.MethodSignature ? factory.createMethodSignature(modifiers, options?.name ?? factory.createIdentifier(""), options?.questionToken, typeParameters, parameters, returnTypeNode) : + kind === SyntaxKind.MethodDeclaration ? factory.createMethodDeclaration(modifiers, /*asteriskToken*/ undefined, options?.name ?? factory.createIdentifier(""), /*questionToken*/ undefined, typeParameters, parameters, returnTypeNode, /*body*/ undefined) : + kind === SyntaxKind.Constructor ? factory.createConstructorDeclaration(modifiers, parameters, /*body*/ undefined) : + kind === SyntaxKind.GetAccessor ? factory.createGetAccessorDeclaration(modifiers, options?.name ?? factory.createIdentifier(""), parameters, returnTypeNode, /*body*/ undefined) : + kind === SyntaxKind.SetAccessor ? factory.createSetAccessorDeclaration(modifiers, options?.name ?? factory.createIdentifier(""), parameters, /*body*/ undefined) : + kind === SyntaxKind.IndexSignature ? factory.createIndexSignature(modifiers, parameters, returnTypeNode) : + kind === SyntaxKind.JSDocFunctionType ? factory.createJSDocFunctionType(parameters, returnTypeNode) : + kind === SyntaxKind.FunctionType ? factory.createFunctionTypeNode(typeParameters, parameters, returnTypeNode ?? factory.createTypeReferenceNode(factory.createIdentifier(""))) : + kind === SyntaxKind.ConstructorType ? factory.createConstructorTypeNode(modifiers, typeParameters, parameters, returnTypeNode ?? factory.createTypeReferenceNode(factory.createIdentifier(""))) : + kind === SyntaxKind.FunctionDeclaration ? factory.createFunctionDeclaration(modifiers, /*asteriskToken*/ undefined, options?.name ? cast(options.name, isIdentifier) : factory.createIdentifier(""), typeParameters, parameters, returnTypeNode, /*body*/ undefined) : + kind === SyntaxKind.FunctionExpression ? factory.createFunctionExpression(modifiers, /*asteriskToken*/ undefined, options?.name ? cast(options.name, isIdentifier) : factory.createIdentifier(""), typeParameters, parameters, returnTypeNode, factory.createBlock([])) : + kind === SyntaxKind.ArrowFunction ? factory.createArrowFunction(modifiers, typeParameters, parameters, returnTypeNode, /*equalsGreaterThanToken*/ undefined, factory.createBlock([])) : + Debug.assertNever(kind); + + if (typeArguments) { + node.typeArguments = factory.createNodeArray(typeArguments); + } + if (signature.declaration?.kind === SyntaxKind.JSDocSignature && signature.declaration.parent.kind === SyntaxKind.JSDocOverloadTag) { + const comment = getTextOfNode(signature.declaration.parent.parent, /*includeTrivia*/ true).slice(2, -2).split(/\r\n|\n|\r/).map(line => line.replace(/^\s+/, " ")).join("\n"); + addSyntheticLeadingComment(node, SyntaxKind.MultiLineCommentTrivia, comment, /*hasTrailingNewLine*/ true); + } + + cleanup?.(); + return node; + } + + type IntroducesNewScopeNode = SignatureDeclaration | JSDocSignature | MappedTypeNode; + + function isNewScopeNode(node: Node): node is IntroducesNewScopeNode { + return isFunctionLike(node) + || isJSDocSignature(node) + || isMappedTypeNode(node); + } + + function getTypeParametersInScope(node: IntroducesNewScopeNode | ConditionalTypeNode) { + return isFunctionLike(node) || isJSDocSignature(node) ? getSignatureFromDeclaration(node).typeParameters : + isConditionalTypeNode(node) ? getInferTypeParameters(node) : + [getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node.typeParameter))]; + } + + function getParametersInScope(node: IntroducesNewScopeNode | ConditionalTypeNode) { + return isFunctionLike(node) || isJSDocSignature(node) ? getSignatureFromDeclaration(node).parameters : undefined; + } + + function enterNewScope( + context: NodeBuilderContext, + declaration: IntroducesNewScopeNode | ConditionalTypeNode | undefined, + expandedParams: readonly Symbol[] | undefined, + typeParameters: readonly TypeParameter[] | undefined, + originalParameters?: readonly Symbol[] | undefined, + mapper?: TypeMapper, + ) { + const cleanupContext = cloneNodeBuilderContext(context); + // For regular function/method declarations, the enclosing declaration will already be signature.declaration, + // so this is a no-op, but for arrow functions and function expressions, the enclosing declaration will be + // the declaration that the arrow function / function expression is assigned to. + // + // If the parameters or return type include "typeof globalThis.paramName", using the wrong scope will lead + // us to believe that we can emit "typeof paramName" instead, even though that would refer to the parameter, + // not the global. Make sure we are in the right scope by changing the enclosingDeclaration to the function. + // + // We can't use the declaration directly; it may be in another file and so we may lose access to symbols + // accessible to the current enclosing declaration, or gain access to symbols not accessible to the current + // enclosing declaration. To keep this chain accurate, insert a fake scope into the chain which makes the + // function's parameters visible. + let cleanupParams: (() => void) | undefined; + let cleanupTypeParams: (() => void) | undefined; + const oldEnclosingDecl = context.enclosingDeclaration; + const oldMapper = context.mapper; + if (mapper) { + context.mapper = mapper; + } + if (context.enclosingDeclaration && declaration) { + // As a performance optimization, reuse the same fake scope within this chain. + // This is especially needed when we are working on an excessively deep type; + // if we don't do this, then we spend all of our time adding more and more + // scopes that need to be searched in isSymbolAccessible later. Since all we + // really want to do is to mark certain names as unavailable, we can just keep + // all of the names we're introducing in one large table and push/pop from it as + // needed; isSymbolAccessible will walk upward and find the closest "fake" scope, + // which will conveniently report on any and all faked scopes in the chain. + // + // It'd likely be better to store this somewhere else for isSymbolAccessible, but + // since that API _only_ uses the enclosing declaration (and its parents), this is + // seems like the best way to inject names into that search process. + // + // Note that we only check the most immediate enclosingDeclaration; the only place we + // could potentially add another fake scope into the chain is right here, so we don't + // traverse all ancestors. + cleanupParams = !some(expandedParams) ? undefined : pushFakeScope( + "params", + add => { + if (!expandedParams) return; + for (let pIndex = 0; pIndex < expandedParams.length; pIndex++) { + const param = expandedParams[pIndex]; + const originalParam = originalParameters?.[pIndex]; + if (originalParameters && originalParam !== param) { + // Can't reference parameters that come from an expansion + add(param.escapedName, unknownSymbol); + // Can't reference the original expanded parameter either + if (originalParam) { + add(originalParam.escapedName, unknownSymbol); + } + } + else if ( + !forEach(param.declarations, d => { + if (isParameter(d) && isBindingPattern(d.name)) { + bindPattern(d.name); + return true; + } + return undefined; + function bindPattern(p: BindingPattern): void { + forEach(p.elements, e => { + switch (e.kind) { + case SyntaxKind.OmittedExpression: + return; + case SyntaxKind.BindingElement: + return bindElement(e); + default: + return Debug.assertNever(e); + } + }); + } + function bindElement(e: BindingElement): void { + if (isBindingPattern(e.name)) { + return bindPattern(e.name); + } + const symbol = getSymbolOfDeclaration(e); + add(symbol.escapedName, symbol); + } + }) + ) { + add(param.escapedName, param); + } + } + }, + ); + + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && some(typeParameters)) { + cleanupTypeParams = pushFakeScope( + "typeParams", + add => { + for (const typeParam of typeParameters ?? emptyArray) { + const typeParamName = typeParameterToName(typeParam, context).escapedText; + add(typeParamName, typeParam.symbol); + } + }, + ); + } + + function pushFakeScope(kind: "params" | "typeParams", addAll: (addSymbol: (name: __String, symbol: Symbol) => void) => void) { + // We only ever need to look two declarations upward. + Debug.assert(context.enclosingDeclaration); + let existingFakeScope: Node | undefined; + if (getNodeLinks(context.enclosingDeclaration).fakeScopeForSignatureDeclaration === kind) { + existingFakeScope = context.enclosingDeclaration; + } + else if (context.enclosingDeclaration.parent && getNodeLinks(context.enclosingDeclaration.parent).fakeScopeForSignatureDeclaration === kind) { + existingFakeScope = context.enclosingDeclaration.parent; + } + Debug.assertOptionalNode(existingFakeScope, isBlock); + + const locals = existingFakeScope?.locals ?? createSymbolTable(); + let newLocals: __String[] | undefined; + let oldLocals: { name: __String; oldSymbol: Symbol; }[] | undefined; + addAll((name, symbol) => { + // Add cleanup information only if we don't own the fake scope + if (existingFakeScope) { + const oldSymbol = locals.get(name); + if (!oldSymbol) { + newLocals = append(newLocals, name); + } + else { + oldLocals = append(oldLocals, { name, oldSymbol }); + } + } + locals.set(name, symbol); + }); + + if (!existingFakeScope) { + // Use a Block for this; the type of the node doesn't matter so long as it + // has locals, and this is cheaper/easier than using a function-ish Node. + const fakeScope = factory.createBlock(emptyArray); + getNodeLinks(fakeScope).fakeScopeForSignatureDeclaration = kind; + fakeScope.locals = locals; + + setParent(fakeScope, context.enclosingDeclaration); + context.enclosingDeclaration = fakeScope; + } + else { + // We did not create the current scope, so we have to clean it up + return function undo() { + forEach(newLocals, s => locals.delete(s)); + forEach(oldLocals, s => locals.set(s.name, s.oldSymbol)); + }; + } + } + } + + return () => { + cleanupParams?.(); + cleanupTypeParams?.(); + cleanupContext(); + context.enclosingDeclaration = oldEnclosingDecl; + context.mapper = oldMapper; + }; + } + + function tryGetThisParameterDeclaration(signature: Signature, context: NodeBuilderContext) { + if (signature.thisParameter) { + return symbolToParameterDeclaration(signature.thisParameter, context); + } + if (signature.declaration && isInJSFile(signature.declaration)) { + const thisTag = getJSDocThisTag(signature.declaration); + if (thisTag && thisTag.typeExpression) { + return factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + "this", + /*questionToken*/ undefined, + typeToTypeNodeHelper(getTypeFromTypeNode(context, thisTag.typeExpression), context), + ); + } + } + } + + function typeParameterToDeclarationWithConstraint(type: TypeParameter, context: NodeBuilderContext, constraintNode: TypeNode | undefined): TypeParameterDeclaration { + const savedContextFlags = context.flags; + context.flags &= ~NodeBuilderFlags.WriteTypeParametersInQualifiedName; // Avoids potential infinite loop when building for a claimspace with a generic + const modifiers = factory.createModifiersFromModifierFlags(getTypeParameterModifiers(type)); + const name = typeParameterToName(type, context); + const defaultParameter = getDefaultFromTypeParameter(type); + const defaultParameterNode = defaultParameter && typeToTypeNodeHelper(defaultParameter, context); + context.flags = savedContextFlags; + return factory.createTypeParameterDeclaration(modifiers, name, constraintNode, defaultParameterNode); + } + + function typeToTypeNodeHelperWithPossibleReusableTypeNode(type: Type, typeNode: TypeNode | undefined, context: NodeBuilderContext) { + return typeNode && tryReuseExistingNonParameterTypeNode(context, typeNode, type) || typeToTypeNodeHelper(type, context); + } + + function typeParameterToDeclaration(type: TypeParameter, context: NodeBuilderContext, constraint = getConstraintOfTypeParameter(type)): TypeParameterDeclaration { + const constraintNode = constraint && typeToTypeNodeHelperWithPossibleReusableTypeNode(constraint, getConstraintDeclaration(type), context); + return typeParameterToDeclarationWithConstraint(type, context, constraintNode); + } + + function typePredicateToTypePredicateNodeHelper(typePredicate: TypePredicate, context: NodeBuilderContext): TypePredicateNode { + const assertsModifier = typePredicate.kind === TypePredicateKind.AssertsThis || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? + factory.createToken(SyntaxKind.AssertsKeyword) : + undefined; + const parameterName = typePredicate.kind === TypePredicateKind.Identifier || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? + setEmitFlags(factory.createIdentifier(typePredicate.parameterName), EmitFlags.NoAsciiEscaping) : + factory.createThisTypeNode(); + const typeNode = typePredicate.type && typeToTypeNodeHelper(typePredicate.type, context); + return factory.createTypePredicateNode(assertsModifier, parameterName, typeNode); + } + + function getEffectiveParameterDeclaration(parameterSymbol: Symbol): ParameterDeclaration | JSDocParameterTag | undefined { + const parameterDeclaration: ParameterDeclaration | JSDocParameterTag | undefined = getDeclarationOfKind(parameterSymbol, SyntaxKind.Parameter); + if (parameterDeclaration) { + return parameterDeclaration; + } + if (!isTransientSymbol(parameterSymbol)) { + return getDeclarationOfKind(parameterSymbol, SyntaxKind.JSDocParameterTag); + } + } + + function symbolToParameterDeclaration(parameterSymbol: Symbol, context: NodeBuilderContext, preserveModifierFlags?: boolean): ParameterDeclaration { + const parameterDeclaration = getEffectiveParameterDeclaration(parameterSymbol); + + const parameterType = getTypeOfSymbol(parameterSymbol); + const parameterTypeNode = serializeTypeForDeclaration(context, parameterDeclaration, parameterType, parameterSymbol); + + const modifiers = !(context.flags & NodeBuilderFlags.OmitParameterModifiers) && preserveModifierFlags && parameterDeclaration && canHaveModifiers(parameterDeclaration) ? map(getModifiers(parameterDeclaration), factory.cloneNode) : undefined; + const isRest = parameterDeclaration && isRestParameter(parameterDeclaration) || getCheckFlags(parameterSymbol) & CheckFlags.RestParameter; + const dotDotDotToken = isRest ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined; + const name = parameterToParameterDeclarationName(parameterSymbol, parameterDeclaration, context); + const isOptional = parameterDeclaration && isOptionalParameter(parameterDeclaration) || getCheckFlags(parameterSymbol) & CheckFlags.OptionalParameter; + const questionToken = isOptional ? factory.createToken(SyntaxKind.QuestionToken) : undefined; + const parameterNode = factory.createParameterDeclaration( + modifiers, + dotDotDotToken, + name, + questionToken, + parameterTypeNode, + /*initializer*/ undefined, + ); + context.approximateLength += symbolName(parameterSymbol).length + 3; + return parameterNode; + } + + function parameterToParameterDeclarationName(parameterSymbol: Symbol, parameterDeclaration: ParameterDeclaration | JSDocParameterTag | undefined, context: NodeBuilderContext) { + return parameterDeclaration ? parameterDeclaration.name ? + parameterDeclaration.name.kind === SyntaxKind.Identifier ? setEmitFlags(factory.cloneNode(parameterDeclaration.name), EmitFlags.NoAsciiEscaping) : + parameterDeclaration.name.kind === SyntaxKind.QualifiedName ? setEmitFlags(factory.cloneNode(parameterDeclaration.name.right), EmitFlags.NoAsciiEscaping) : + cloneBindingName(parameterDeclaration.name) : + symbolName(parameterSymbol) : + symbolName(parameterSymbol); + + function cloneBindingName(node: BindingName): BindingName { + return elideInitializerAndSetEmitFlags(node) as BindingName; + function elideInitializerAndSetEmitFlags(node: Node): Node { + if (context.tracker.canTrackSymbol && isComputedPropertyName(node) && isLateBindableName(node)) { + trackComputedName(node.expression, context.enclosingDeclaration, context); + } + let visited = visitEachChildWorker(node, elideInitializerAndSetEmitFlags, /*context*/ undefined, /*nodesVisitor*/ undefined, elideInitializerAndSetEmitFlags); + if (isBindingElement(visited)) { + visited = factory.updateBindingElement( + visited, + visited.dotDotDotToken, + visited.propertyName, + visited.name, + /*initializer*/ undefined, + ); + } + if (!nodeIsSynthesized(visited)) { + visited = factory.cloneNode(visited); + } + return setEmitFlags(visited, EmitFlags.SingleLine | EmitFlags.NoAsciiEscaping); + } + } + } + + function trackComputedName(accessExpression: EntityNameOrEntityNameExpression, enclosingDeclaration: Node | undefined, context: NodeBuilderContext) { + if (!context.tracker.canTrackSymbol) return; + // get symbol of the first identifier of the entityName + const firstIdentifier = getFirstIdentifier(accessExpression); + const name = resolveName(firstIdentifier, firstIdentifier.escapedText, SymbolFlags.Value | SymbolFlags.ExportValue, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (name) { + context.tracker.trackSymbol(name, enclosingDeclaration, SymbolFlags.Value); + } + } + + function lookupSymbolChain(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, yieldModuleSymbol?: boolean) { + context.tracker.trackSymbol(symbol, context.enclosingDeclaration, meaning); + return lookupSymbolChainWorker(symbol, context, meaning, yieldModuleSymbol); + } + + function lookupSymbolChainWorker(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, yieldModuleSymbol?: boolean) { + // Try to get qualified name if the symbol is not a type parameter and there is an enclosing declaration. + let chain: Symbol[]; + const isTypeParameter = symbol.flags & SymbolFlags.TypeParameter; + if (!isTypeParameter && (context.enclosingDeclaration || context.flags & NodeBuilderFlags.UseFullyQualifiedType) && !(context.flags & NodeBuilderFlags.DoNotIncludeSymbolChain)) { + chain = Debug.checkDefined(getSymbolChain(symbol, meaning, /*endOfChain*/ true)); + Debug.assert(chain && chain.length > 0); + } + else { + chain = [symbol]; + } + return chain; + + /** @param endOfChain Set to false for recursive calls; non-recursive calls should always output something. */ + function getSymbolChain(symbol: Symbol, meaning: SymbolFlags, endOfChain: boolean): Symbol[] | undefined { + let accessibleSymbolChain = getAccessibleSymbolChain(symbol, context.enclosingDeclaration, meaning, !!(context.flags & NodeBuilderFlags.UseOnlyExternalAliasing)); + let parentSpecifiers: (string | undefined)[]; + if ( + !accessibleSymbolChain || + needsQualification(accessibleSymbolChain[0], context.enclosingDeclaration, accessibleSymbolChain.length === 1 ? meaning : getQualifiedLeftMeaning(meaning)) + ) { + // Go up and add our parent. + const parents = getContainersOfSymbol(accessibleSymbolChain ? accessibleSymbolChain[0] : symbol, context.enclosingDeclaration, meaning); + if (length(parents)) { + parentSpecifiers = parents!.map(symbol => + some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol) + ? getSpecifierForModuleSymbol(symbol, context) + : undefined + ); + const indices = parents!.map((_, i) => i); + indices.sort(sortByBestName); + const sortedParents = indices.map(i => parents![i]); + for (const parent of sortedParents) { + const parentChain = getSymbolChain(parent, getQualifiedLeftMeaning(meaning), /*endOfChain*/ false); + if (parentChain) { + if ( + parent.exports && parent.exports.get(InternalSymbolName.ExportEquals) && + getSymbolIfSameReference(parent.exports.get(InternalSymbolName.ExportEquals)!, symbol) + ) { + // parentChain root _is_ symbol - symbol is a module export=, so it kinda looks like it's own parent + // No need to lookup an alias for the symbol in itself + accessibleSymbolChain = parentChain; + break; + } + accessibleSymbolChain = parentChain.concat(accessibleSymbolChain || [getAliasForSymbolInContainer(parent, symbol) || symbol]); + break; + } + } + } + } + + if (accessibleSymbolChain) { + return accessibleSymbolChain; + } + if ( + // If this is the last part of outputting the symbol, always output. The cases apply only to parent symbols. + endOfChain || + // If a parent symbol is an anonymous type, don't write it. + !(symbol.flags & (SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral)) + ) { + // If a parent symbol is an external module, don't write it. (We prefer just `x` vs `"foo/bar".x`.) + if (!endOfChain && !yieldModuleSymbol && !!forEach(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + return; + } + return [symbol]; + } + + function sortByBestName(a: number, b: number) { + const specifierA = parentSpecifiers[a]; + const specifierB = parentSpecifiers[b]; + if (specifierA && specifierB) { + const isBRelative = pathIsRelative(specifierB); + if (pathIsRelative(specifierA) === isBRelative) { + // Both relative or both non-relative, sort by number of parts + return moduleSpecifiers.countPathComponents(specifierA) - moduleSpecifiers.countPathComponents(specifierB); + } + if (isBRelative) { + // A is non-relative, B is relative: prefer A + return -1; + } + // A is relative, B is non-relative: prefer B + return 1; + } + return 0; + } + } + } + + function typeParametersToTypeParameterDeclarations(symbol: Symbol, context: NodeBuilderContext) { + let typeParameterNodes: NodeArray | undefined; + const targetSymbol = getTargetSymbol(symbol); + if (targetSymbol.flags & (SymbolFlags.Class | SymbolFlags.Interface | SymbolFlags.TypeAlias)) { + typeParameterNodes = factory.createNodeArray(map(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol), tp => typeParameterToDeclaration(tp, context))); + } + return typeParameterNodes; + } + + function lookupTypeParameterNodes(chain: Symbol[], index: number, context: NodeBuilderContext) { + Debug.assert(chain && 0 <= index && index < chain.length); + const symbol = chain[index]; + const symbolId = getSymbolId(symbol); + if (context.typeParameterSymbolList?.has(symbolId)) { + return undefined; + } + if (context.mustCreateTypeParameterSymbolList) { + context.mustCreateTypeParameterSymbolList = false; + context.typeParameterSymbolList = new Set(context.typeParameterSymbolList); + } + context.typeParameterSymbolList!.add(symbolId); + let typeParameterNodes: readonly TypeNode[] | readonly TypeParameterDeclaration[] | undefined; + if (context.flags & NodeBuilderFlags.WriteTypeParametersInQualifiedName && index < (chain.length - 1)) { + const parentSymbol = symbol; + const nextSymbol = chain[index + 1]; + if (getCheckFlags(nextSymbol) & CheckFlags.Instantiated) { + const params = getTypeParametersOfClassOrInterface( + parentSymbol.flags & SymbolFlags.Alias ? resolveAlias(parentSymbol) : parentSymbol, + ); + // NOTE: cast to TransientSymbol should be safe because only TransientSymbol can have CheckFlags.Instantiated + typeParameterNodes = mapToTypeNodes(map(params, t => getMappedType(t, (nextSymbol as TransientSymbol).links.mapper!)), context); + } + else { + typeParameterNodes = typeParametersToTypeParameterDeclarations(symbol, context); + } + } + return typeParameterNodes; + } + + /** + * Given A[B][C][D], finds A[B] + */ + function getTopmostIndexedAccessType(top: IndexedAccessTypeNode): IndexedAccessTypeNode { + if (isIndexedAccessTypeNode(top.objectType)) { + return getTopmostIndexedAccessType(top.objectType); + } + return top; + } + + function getSpecifierForModuleSymbol(symbol: Symbol, context: NodeBuilderContext, overrideImportMode?: ResolutionMode) { + let file = getDeclarationOfKind(symbol, SyntaxKind.SourceFile); + if (!file) { + const equivalentFileSymbol = firstDefined(symbol.declarations, d => getFileSymbolIfFileSymbolExportEqualsContainer(d, symbol)); + if (equivalentFileSymbol) { + file = getDeclarationOfKind(equivalentFileSymbol, SyntaxKind.SourceFile); + } + } + if (file && file.moduleName !== undefined) { + // Use the amd name if it is available + return file.moduleName; + } + if (!file) { + if (ambientModuleSymbolRegex.test(symbol.escapedName as string)) { + return (symbol.escapedName as string).substring(1, (symbol.escapedName as string).length - 1); + } + } + if (!context.enclosingFile || !context.tracker.moduleResolverHost) { + // If there's no context declaration, we can't lookup a non-ambient specifier, so we just use the symbol name + if (ambientModuleSymbolRegex.test(symbol.escapedName as string)) { + return (symbol.escapedName as string).substring(1, (symbol.escapedName as string).length - 1); + } + return getSourceFileOfNode(getNonAugmentationDeclaration(symbol)!).fileName; // A resolver may not be provided for baselines and errors - in those cases we use the fileName in full + } + const contextFile = context.enclosingFile; + const resolutionMode = overrideImportMode || contextFile?.impliedNodeFormat; + const cacheKey = createModeAwareCacheKey(contextFile.path, resolutionMode); + const links = getSymbolLinks(symbol); + let specifier = links.specifierCache && links.specifierCache.get(cacheKey); + if (!specifier) { + const isBundle = !!compilerOptions.outFile; + // For declaration bundles, we need to generate absolute paths relative to the common source dir for imports, + // just like how the declaration emitter does for the ambient module declarations - we can easily accomplish this + // using the `baseUrl` compiler option (which we would otherwise never use in declaration emit) and a non-relative + // specifier preference + const { moduleResolverHost } = context.tracker; + const specifierCompilerOptions = isBundle ? { ...compilerOptions, baseUrl: moduleResolverHost.getCommonSourceDirectory() } : compilerOptions; + specifier = first(moduleSpecifiers.getModuleSpecifiers( + symbol, + checker, + specifierCompilerOptions, + contextFile, + moduleResolverHost, + { + importModuleSpecifierPreference: isBundle ? "non-relative" : "project-relative", + importModuleSpecifierEnding: isBundle ? "minimal" + : resolutionMode === ModuleKind.ESNext ? "js" + : undefined, + }, + { overrideImportMode }, + )); + links.specifierCache ??= new Map(); + links.specifierCache.set(cacheKey, specifier); + } + return specifier; + } + + function symbolToEntityNameNode(symbol: Symbol): EntityName { + const identifier = factory.createIdentifier(unescapeLeadingUnderscores(symbol.escapedName)); + return symbol.parent ? factory.createQualifiedName(symbolToEntityNameNode(symbol.parent), identifier) : identifier; + } + + function symbolToTypeNode(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, overrideTypeArguments?: readonly TypeNode[]): TypeNode { + const chain = lookupSymbolChain(symbol, context, meaning, !(context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope)); // If we're using aliases outside the current scope, dont bother with the module + + const isTypeOf = meaning === SymbolFlags.Value; + if (some(chain[0].declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + // module is root, must use `ImportTypeNode` + const nonRootParts = chain.length > 1 ? createAccessFromSymbolChain(chain, chain.length - 1, 1) : undefined; + const typeParameterNodes = overrideTypeArguments || lookupTypeParameterNodes(chain, 0, context); + const contextFile = getSourceFileOfNode(getOriginalNode(context.enclosingDeclaration)); + const targetFile = getSourceFileOfModule(chain[0]); + let specifier: string | undefined; + let attributes: ImportAttributes | undefined; + if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) { + // An `import` type directed at an esm format file is only going to resolve in esm mode - set the esm mode assertion + if (targetFile?.impliedNodeFormat === ModuleKind.ESNext && targetFile.impliedNodeFormat !== contextFile?.impliedNodeFormat) { + specifier = getSpecifierForModuleSymbol(chain[0], context, ModuleKind.ESNext); + attributes = factory.createImportAttributes( + factory.createNodeArray([ + factory.createImportAttribute( + factory.createStringLiteral("resolution-mode"), + factory.createStringLiteral("import"), + ), + ]), + ); + } + } + if (!specifier) { + specifier = getSpecifierForModuleSymbol(chain[0], context); + } + if (!(context.flags & NodeBuilderFlags.AllowNodeModulesRelativePaths) && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Classic && specifier.includes("/node_modules/")) { + const oldSpecifier = specifier; + if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) { + // We might be able to write a portable import type using a mode override; try specifier generation again, but with a different mode set + const swappedMode = contextFile?.impliedNodeFormat === ModuleKind.ESNext ? ModuleKind.CommonJS : ModuleKind.ESNext; + specifier = getSpecifierForModuleSymbol(chain[0], context, swappedMode); + + if (specifier.includes("/node_modules/")) { + // Still unreachable :( + specifier = oldSpecifier; + } + else { + attributes = factory.createImportAttributes( + factory.createNodeArray([ + factory.createImportAttribute( + factory.createStringLiteral("resolution-mode"), + factory.createStringLiteral(swappedMode === ModuleKind.ESNext ? "import" : "require"), + ), + ]), + ); + } + } + + if (!attributes) { + // If ultimately we can only name the symbol with a reference that dives into a `node_modules` folder, we should error + // since declaration files with these kinds of references are liable to fail when published :( + context.encounteredError = true; + if (context.tracker.reportLikelyUnsafeImportRequiredError) { + context.tracker.reportLikelyUnsafeImportRequiredError(oldSpecifier); + } + } + } + const lit = factory.createLiteralTypeNode(factory.createStringLiteral(specifier)); + context.approximateLength += specifier.length + 10; // specifier + import("") + if (!nonRootParts || isEntityName(nonRootParts)) { + if (nonRootParts) { + const lastId = isIdentifier(nonRootParts) ? nonRootParts : nonRootParts.right; + setIdentifierTypeArguments(lastId, /*typeArguments*/ undefined); + } + return factory.createImportTypeNode(lit, attributes, nonRootParts as EntityName, typeParameterNodes as readonly TypeNode[], isTypeOf); + } + else { + const splitNode = getTopmostIndexedAccessType(nonRootParts); + const qualifier = (splitNode.objectType as TypeReferenceNode).typeName; + return factory.createIndexedAccessTypeNode(factory.createImportTypeNode(lit, attributes, qualifier, typeParameterNodes as readonly TypeNode[], isTypeOf), splitNode.indexType); + } + } + + const entityName = createAccessFromSymbolChain(chain, chain.length - 1, 0); + if (isIndexedAccessTypeNode(entityName)) { + return entityName; // Indexed accesses can never be `typeof` + } + if (isTypeOf) { + return factory.createTypeQueryNode(entityName); + } + else { + const lastId = isIdentifier(entityName) ? entityName : entityName.right; + const lastTypeArgs = getIdentifierTypeArguments(lastId); + setIdentifierTypeArguments(lastId, /*typeArguments*/ undefined); + return factory.createTypeReferenceNode(entityName, lastTypeArgs as NodeArray); + } + + function createAccessFromSymbolChain(chain: Symbol[], index: number, stopper: number): EntityName | IndexedAccessTypeNode { + const typeParameterNodes = index === (chain.length - 1) ? overrideTypeArguments : lookupTypeParameterNodes(chain, index, context); + const symbol = chain[index]; + const parent = chain[index - 1]; + + let symbolName: string | undefined; + if (index === 0) { + context.flags |= NodeBuilderFlags.InInitialEntityName; + symbolName = getNameOfSymbolAsWritten(symbol, context); + context.approximateLength += (symbolName ? symbolName.length : 0) + 1; + context.flags ^= NodeBuilderFlags.InInitialEntityName; + } + else { + if (parent && getExportsOfSymbol(parent)) { + const exports = getExportsOfSymbol(parent); + forEachEntry(exports, (ex, name) => { + if (getSymbolIfSameReference(ex, symbol) && !isLateBoundName(name) && name !== InternalSymbolName.ExportEquals) { + symbolName = unescapeLeadingUnderscores(name); + return true; + } + }); + } + } + + if (symbolName === undefined) { + const name = firstDefined(symbol.declarations, getNameOfDeclaration); + if (name && isComputedPropertyName(name) && isEntityName(name.expression)) { + const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); + if (isEntityName(LHS)) { + return factory.createIndexedAccessTypeNode(factory.createParenthesizedType(factory.createTypeQueryNode(LHS)), factory.createTypeQueryNode(name.expression)); + } + return LHS; + } + symbolName = getNameOfSymbolAsWritten(symbol, context); + } + context.approximateLength += symbolName.length + 1; + + if ( + !(context.flags & NodeBuilderFlags.ForbidIndexedAccessSymbolReferences) && parent && + getMembersOfSymbol(parent) && getMembersOfSymbol(parent).get(symbol.escapedName) && + getSymbolIfSameReference(getMembersOfSymbol(parent).get(symbol.escapedName)!, symbol) + ) { + // Should use an indexed access + const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); + if (isIndexedAccessTypeNode(LHS)) { + return factory.createIndexedAccessTypeNode(LHS, factory.createLiteralTypeNode(factory.createStringLiteral(symbolName))); + } + else { + return factory.createIndexedAccessTypeNode(factory.createTypeReferenceNode(LHS, typeParameterNodes as readonly TypeNode[]), factory.createLiteralTypeNode(factory.createStringLiteral(symbolName))); + } + } + + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + + if (index > stopper) { + const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); + if (!isEntityName(LHS)) { + return Debug.fail("Impossible construct - an export of an indexed access cannot be reachable"); + } + return factory.createQualifiedName(LHS, identifier); + } + return identifier; + } + } + + function typeParameterShadowsOtherTypeParameterInScope(escapedName: __String, context: NodeBuilderContext, type: TypeParameter) { + const result = resolveName(context.enclosingDeclaration, escapedName, SymbolFlags.Type, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (result && result.flags & SymbolFlags.TypeParameter) { + return result !== type.symbol; + } + return false; + } + + function typeParameterToName(type: TypeParameter, context: NodeBuilderContext) { + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && context.typeParameterNames) { + const cached = context.typeParameterNames.get(getTypeId(type)); + if (cached) { + return cached; + } + } + let result = symbolToName(type.symbol, context, SymbolFlags.Type, /*expectsIdentifier*/ true); + if (!(result.kind & SyntaxKind.Identifier)) { + return factory.createIdentifier("(Missing type parameter)"); + } + const decl = type.symbol?.declarations?.[0]; + if (decl && isTypeParameterDeclaration(decl)) { + result = setTextRange(context, result, decl.name); + } + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { + const rawtext = result.escapedText as string; + let i = context.typeParameterNamesByTextNextNameCount?.get(rawtext) || 0; + let text = rawtext; + while (context.typeParameterNamesByText?.has(text) || typeParameterShadowsOtherTypeParameterInScope(text as __String, context, type)) { + i++; + text = `${rawtext}_${i}`; + } + if (text !== rawtext) { + const typeArguments = getIdentifierTypeArguments(result); + result = factory.createIdentifier(text); + setIdentifierTypeArguments(result, typeArguments); + } + if (context.mustCreateTypeParametersNamesLookups) { + context.mustCreateTypeParametersNamesLookups = false; + context.typeParameterNames = new Map(context.typeParameterNames); + context.typeParameterNamesByTextNextNameCount = new Map(context.typeParameterNamesByTextNextNameCount); + context.typeParameterNamesByText = new Set(context.typeParameterNamesByText); + } + // avoiding iterations of the above loop turns out to be worth it when `i` starts to get large, so we cache the max + // `i` we've used thus far, to save work later + context.typeParameterNamesByTextNextNameCount!.set(rawtext, i); + context.typeParameterNames!.set(getTypeId(type), result); + context.typeParameterNamesByText!.add(text); + } + return result; + } + + function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: true): Identifier; + function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: false): EntityName; + function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: boolean): EntityName { + const chain = lookupSymbolChain(symbol, context, meaning); + + if ( + expectsIdentifier && chain.length !== 1 + && !context.encounteredError + && !(context.flags & NodeBuilderFlags.AllowQualifiedNameInPlaceOfIdentifier) + ) { + context.encounteredError = true; + } + return createEntityNameFromSymbolChain(chain, chain.length - 1); + + function createEntityNameFromSymbolChain(chain: Symbol[], index: number): EntityName { + const typeParameterNodes = lookupTypeParameterNodes(chain, index, context); + const symbol = chain[index]; + + if (index === 0) { + context.flags |= NodeBuilderFlags.InInitialEntityName; + } + const symbolName = getNameOfSymbolAsWritten(symbol, context); + if (index === 0) { + context.flags ^= NodeBuilderFlags.InInitialEntityName; + } + + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + + return index > 0 ? factory.createQualifiedName(createEntityNameFromSymbolChain(chain, index - 1), identifier) : identifier; + } + } + + function symbolToExpression(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags) { + const chain = lookupSymbolChain(symbol, context, meaning); + + return createExpressionFromSymbolChain(chain, chain.length - 1); + + function createExpressionFromSymbolChain(chain: Symbol[], index: number): Expression { + const typeParameterNodes = lookupTypeParameterNodes(chain, index, context); + const symbol = chain[index]; + + if (index === 0) { + context.flags |= NodeBuilderFlags.InInitialEntityName; + } + let symbolName = getNameOfSymbolAsWritten(symbol, context); + if (index === 0) { + context.flags ^= NodeBuilderFlags.InInitialEntityName; + } + let firstChar = symbolName.charCodeAt(0); + + if (isSingleOrDoubleQuote(firstChar) && some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + return factory.createStringLiteral(getSpecifierForModuleSymbol(symbol, context)); + } + if (index === 0 || canUsePropertyAccess(symbolName, languageVersion)) { + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + + return index > 0 ? factory.createPropertyAccessExpression(createExpressionFromSymbolChain(chain, index - 1), identifier) : identifier; + } + else { + if (firstChar === CharacterCodes.openBracket) { + symbolName = symbolName.substring(1, symbolName.length - 1); + firstChar = symbolName.charCodeAt(0); + } + let expression: Expression | undefined; + if (isSingleOrDoubleQuote(firstChar) && !(symbol.flags & SymbolFlags.EnumMember)) { + expression = factory.createStringLiteral(stripQuotes(symbolName).replace(/\\./g, s => s.substring(1)), firstChar === CharacterCodes.singleQuote); + } + else if (("" + +symbolName) === symbolName) { + expression = factory.createNumericLiteral(+symbolName); + } + if (!expression) { + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + expression = identifier; + } + return factory.createElementAccessExpression(createExpressionFromSymbolChain(chain, index - 1), expression); + } + } + } + + function isStringNamed(d: Declaration) { + const name = getNameOfDeclaration(d); + if (!name) { + return false; + } + if (isComputedPropertyName(name)) { + const type = checkExpression(name.expression); + return !!(type.flags & TypeFlags.StringLike); + } + if (isElementAccessExpression(name)) { + const type = checkExpression(name.argumentExpression); + return !!(type.flags & TypeFlags.StringLike); + } + return isStringLiteral(name); + } + + function isSingleQuotedStringNamed(d: Declaration) { + const name = getNameOfDeclaration(d); + return !!(name && isStringLiteral(name) && (name.singleQuote || !nodeIsSynthesized(name) && startsWith(getTextOfNode(name, /*includeTrivia*/ false), "'"))); + } + + function getPropertyNameNodeForSymbol(symbol: Symbol, context: NodeBuilderContext) { + const stringNamed = !!length(symbol.declarations) && every(symbol.declarations, isStringNamed); + const singleQuote = !!length(symbol.declarations) && every(symbol.declarations, isSingleQuotedStringNamed); + const isMethod = !!(symbol.flags & SymbolFlags.Method); + const fromNameType = getPropertyNameNodeForSymbolFromNameType(symbol, context, singleQuote, stringNamed, isMethod); + if (fromNameType) { + return fromNameType; + } + const rawName = unescapeLeadingUnderscores(symbol.escapedName); + return createPropertyNameNodeForIdentifierOrLiteral(rawName, getEmitScriptTarget(compilerOptions), singleQuote, stringNamed, isMethod); + } + + // See getNameForSymbolFromNameType for a stringy equivalent + function getPropertyNameNodeForSymbolFromNameType(symbol: Symbol, context: NodeBuilderContext, singleQuote: boolean, stringNamed: boolean, isMethod: boolean) { + const nameType = getSymbolLinks(symbol).nameType; + if (nameType) { + if (nameType.flags & TypeFlags.StringOrNumberLiteral) { + const name = "" + (nameType as StringLiteralType | NumberLiteralType).value; + if (!isIdentifierText(name, getEmitScriptTarget(compilerOptions)) && (stringNamed || !isNumericLiteralName(name))) { + return factory.createStringLiteral(name, !!singleQuote); + } + if (isNumericLiteralName(name) && startsWith(name, "-")) { + return factory.createComputedPropertyName(factory.createPrefixUnaryExpression(SyntaxKind.MinusToken, factory.createNumericLiteral(-name))); + } + return createPropertyNameNodeForIdentifierOrLiteral(name, getEmitScriptTarget(compilerOptions), singleQuote, stringNamed, isMethod); + } + if (nameType.flags & TypeFlags.UniqueESSymbol) { + return factory.createComputedPropertyName(symbolToExpression((nameType as UniqueESSymbolType).symbol, context, SymbolFlags.Value)); + } + } + } + + function cloneNodeBuilderContext(context: NodeBuilderContext) { + // Make type parameters created within this context not consume the name outside this context + // The symbol serializer ends up creating many sibling scopes that all need "separate" contexts when + // it comes to naming things - within a normal `typeToTypeNode` call, the node builder only ever descends + // through the type tree, so the only cases where we could have used distinct sibling scopes was when there + // were multiple generic overloads with similar generated type parameter names + // The effect: + // When we write out + // export const x: (x: T) => T + // export const y: (x: T) => T + // we write it out like that, rather than as + // export const x: (x: T) => T + // export const y: (x: T_1) => T_1 + const oldMustCreateTypeParameterSymbolList = context.mustCreateTypeParameterSymbolList; + const oldMustCreateTypeParametersNamesLookups = context.mustCreateTypeParametersNamesLookups; + context.mustCreateTypeParameterSymbolList = true; + context.mustCreateTypeParametersNamesLookups = true; + const oldTypeParameterNames = context.typeParameterNames; + const oldTypeParameterNamesByText = context.typeParameterNamesByText; + const oldTypeParameterNamesByTextNextNameCount = context.typeParameterNamesByTextNextNameCount; + const oldTypeParameterSymbolList = context.typeParameterSymbolList; + return () => { + context.typeParameterNames = oldTypeParameterNames; + context.typeParameterNamesByText = oldTypeParameterNamesByText; + context.typeParameterNamesByTextNextNameCount = oldTypeParameterNamesByTextNextNameCount; + context.typeParameterSymbolList = oldTypeParameterSymbolList; + context.mustCreateTypeParameterSymbolList = oldMustCreateTypeParameterSymbolList; + context.mustCreateTypeParametersNamesLookups = oldMustCreateTypeParametersNamesLookups; + }; + } + + function getDeclarationWithTypeAnnotation(symbol: Symbol, enclosingDeclaration?: Node | undefined) { + return symbol.declarations && find(symbol.declarations, s => !!getNonlocalEffectiveTypeAnnotationNode(s) && (!enclosingDeclaration || !!findAncestor(s, n => n === enclosingDeclaration))); + } + + function existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing: TypeNode, type: Type) { + // In JS, you can say something like `Foo` and get a `Foo` implicitly - we don't want to preserve that original `Foo` in these cases, though. + if (!(getObjectFlags(type) & ObjectFlags.Reference)) return true; + if (!isTypeReferenceNode(existing)) return true; + // `type` is a reference type, and `existing` is a type reference node, but we still need to make sure they refer to the _same_ target type + // before we go comparing their type argument counts. + void getTypeFromTypeReference(existing); // call to ensure symbol is resolved + const symbol = getNodeLinks(existing).resolvedSymbol; + const existingTarget = symbol && getDeclaredTypeOfSymbol(symbol); + if (!existingTarget || existingTarget !== (type as TypeReference).target) return true; + return length(existing.typeArguments) >= getMinTypeArgumentCount((type as TypeReference).target.typeParameters); + } + + function getEnclosingDeclarationIgnoringFakeScope(enclosingDeclaration: Node) { + while (getNodeLinks(enclosingDeclaration).fakeScopeForSignatureDeclaration) { + enclosingDeclaration = enclosingDeclaration.parent; + } + return enclosingDeclaration; + } + + /** + * Unlike `typeToTypeNodeHelper`, this handles setting up the `AllowUniqueESSymbolType` flag + * so a `unique symbol` is returned when appropriate for the input symbol, rather than `typeof sym` + * @param context - The node builder context. Any reused nodes are checked to be pulled from within the scope of the context's enclosingDeclaration. + * @param declaration - The preferred declaration to pull existing type nodes from (the symbol will be used as a fallback to find any annotated declaration) + * @param type - The type to write; an existing annotation must match this type if it's used, otherwise this is the type serialized as a new type node + * @param symbol - The symbol is used both to find an existing annotation if declaration is not provided, and to determine if `unique symbol` should be printed + */ + function serializeTypeForDeclaration(context: NodeBuilderContext, declaration: Declaration | undefined, type: Type, symbol: Symbol) { + const addUndefined = declaration && (isParameter(declaration) || isJSDocParameterTag(declaration)) && requiresAddingImplicitUndefined(declaration); + const enclosingDeclaration = context.enclosingDeclaration; + const oldFlags = context.flags; + if (declaration && hasInferredType(declaration) && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) { + syntacticNodeBuilder.serializeTypeOfDeclaration(declaration, context); + } + context.flags |= NodeBuilderFlags.NoSyntacticPrinter; + if (enclosingDeclaration && (!isErrorType(type) || (context.flags & NodeBuilderFlags.AllowUnresolvedNames))) { + const declWithExistingAnnotation = declaration && getNonlocalEffectiveTypeAnnotationNode(declaration) + ? declaration + : getDeclarationWithTypeAnnotation(symbol); + if (declWithExistingAnnotation && !isFunctionLikeDeclaration(declWithExistingAnnotation) && !isGetAccessorDeclaration(declWithExistingAnnotation)) { + // try to reuse the existing annotation + const existing = getNonlocalEffectiveTypeAnnotationNode(declWithExistingAnnotation)!; + const result = !isTypePredicateNode(existing) && tryReuseExistingTypeNode(context, existing, type, declWithExistingAnnotation, addUndefined); + if (result) { + context.flags = oldFlags; + return result; + } + } + } + if ( + type.flags & TypeFlags.UniqueESSymbol && + type.symbol === symbol && (!context.enclosingDeclaration || some(symbol.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(context.enclosingDeclaration!))) + ) { + context.flags |= NodeBuilderFlags.AllowUniqueESSymbolType; + } + + const decl = declaration ?? symbol.valueDeclaration ?? symbol.declarations?.[0]; + const expr = decl && isDeclarationWithPossibleInnerTypeNodeReuse(decl) ? getPossibleTypeNodeReuseExpression(decl) : undefined; + + const result = expressionOrTypeToTypeNode(context, expr, type, addUndefined); + context.flags = oldFlags; + return result; + } + + function typeNodeIsEquivalentToType(annotatedDeclaration: Node | undefined, type: Type, typeFromTypeNode: Type) { + if (typeFromTypeNode === type) { + return true; + } + if (annotatedDeclaration && (isParameter(annotatedDeclaration) || isPropertySignature(annotatedDeclaration) || isPropertyDeclaration(annotatedDeclaration)) && annotatedDeclaration.questionToken) { + return getTypeWithFacts(type, TypeFacts.NEUndefined) === typeFromTypeNode; + } + return false; + } + + function serializeReturnTypeForSignature(context: NodeBuilderContext, signature: Signature) { + const suppressAny = context.flags & NodeBuilderFlags.SuppressAnyReturnType; + const flags = context.flags; + if (suppressAny) context.flags &= ~NodeBuilderFlags.SuppressAnyReturnType; // suppress only toplevel `any`s + let returnTypeNode: TypeNode | undefined; + const returnType = getReturnTypeOfSignature(signature); + if (returnType && !(suppressAny && isTypeAny(returnType))) { + if (signature.declaration && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) { + syntacticNodeBuilder.serializeReturnTypeForSignature(signature.declaration, context); + } + context.flags |= NodeBuilderFlags.NoSyntacticPrinter; + returnTypeNode = serializeReturnTypeForSignatureWorker(context, signature); + } + else if (!suppressAny) { + returnTypeNode = factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + context.flags = flags; + return returnTypeNode; + } + + function serializeReturnTypeForSignatureWorker(context: NodeBuilderContext, signature: Signature) { + const typePredicate = getTypePredicateOfSignature(signature); + const type = getReturnTypeOfSignature(signature); + if (context.enclosingDeclaration && (!isErrorType(type) || (context.flags & NodeBuilderFlags.AllowUnresolvedNames)) && signature.declaration && !nodeIsSynthesized(signature.declaration)) { + const annotation = signature.declaration && getNonlocalEffectiveReturnTypeAnnotationNode(signature.declaration); + // Default constructor signatures inherited from base classes return the derived class but have the base class declaration + // To ensure we don't serialize the wrong type we check that that return type of the signature corresponds to the declaration return type signature + if (annotation && getTypeFromTypeNode(context, annotation) === type) { + const result = tryReuseExistingTypeNodeHelper(context, annotation); + if (result) { + return result; + } + } + } + if (typePredicate) { + return typePredicateToTypePredicateNodeHelper(typePredicate, context); + } + const expr = signature.declaration && getPossibleTypeNodeReuseExpression(signature.declaration); + return expressionOrTypeToTypeNode(context, expr, type); + } + + function trackExistingEntityName(node: T, context: NodeBuilderContext) { + let introducesError = false; + const leftmost = getFirstIdentifier(node); + if (isInJSFile(node) && (isExportsIdentifier(leftmost) || isModuleExportsAccessExpression(leftmost.parent) || (isQualifiedName(leftmost.parent) && isModuleIdentifier(leftmost.parent.left) && isExportsIdentifier(leftmost.parent.right)))) { + introducesError = true; + return { introducesError, node }; + } + const meaning = getMeaningOfEntityNameReference(node); + let sym: Symbol | undefined; + if (isThisIdentifier(leftmost)) { + // `this` isn't a bindable identifier - skip resolution, find a relevant `this` symbol directly and avoid exhaustive scope traversal + sym = getSymbolOfDeclaration(getThisContainer(leftmost, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)); + if (isSymbolAccessible(sym, leftmost, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible) { + introducesError = true; + context.tracker.reportInaccessibleThisError(); + } + return { introducesError, node: attachSymbolToLeftmostIdentifier(node) as T }; + } + sym = resolveEntityName(leftmost, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true); + if ( + context.enclosingDeclaration && + !(sym && sym.flags & SymbolFlags.TypeParameter) + ) { + sym = getExportSymbolOfValueSymbolIfExported(sym); + // Some declarations may be transplanted to a new location. + // When this happens we need to make sure that the name has the same meaning at both locations + // We also check for the unknownSymbol because when we create a fake scope some parameters may actually not be usable + // either because they are the expanded rest parameter, + // or because they are the newly added parameters from the tuple, which might have different meanings in the original context + const symAtLocation = resolveEntityName(leftmost, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, context.enclosingDeclaration); + if ( + // Check for unusable parameters symbols + symAtLocation === unknownSymbol || + // If the symbol is not found, but was not found in the original scope either we probably have an error, don't reuse the node + (symAtLocation === undefined && sym !== undefined) || + // If the symbol is found both in declaration scope and in current scope then it shoudl point to the same reference + (symAtLocation && sym && !getSymbolIfSameReference(getExportSymbolOfValueSymbolIfExported(symAtLocation), sym)) + ) { + // In isolated declaration we will not do rest parameter expansion so there is no need to report on these. + if (symAtLocation !== unknownSymbol) { + context.tracker.reportInferenceFallback(node); + } + introducesError = true; + return { introducesError, node, sym }; + } + } + + if (sym) { + // If a parameter is resolvable in the current context it is also visible, so no need to go to symbol accesibility + if ( + sym.flags & SymbolFlags.FunctionScopedVariable + && sym.valueDeclaration + ) { + if (isPartOfParameterDeclaration(sym.valueDeclaration) || isJSDocParameterTag(sym.valueDeclaration)) { + return { introducesError, node: attachSymbolToLeftmostIdentifier(node) as T }; + } + } + if ( + !(sym.flags & SymbolFlags.TypeParameter) && // Type parameters are visible in the current context if they are are resolvable + !isDeclarationName(node) && + isSymbolAccessible(sym, context.enclosingDeclaration, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible + ) { + context.tracker.reportInferenceFallback(node); + introducesError = true; + } + else { + context.tracker.trackSymbol(sym, context.enclosingDeclaration, meaning); + } + return { introducesError, node: attachSymbolToLeftmostIdentifier(node) as T }; + } + + return { introducesError, node }; + + /** + * Attaches a `.symbol` member to an identifier, cloning it to do so, so symbol information + * is smuggled out for symbol display information. + */ + function attachSymbolToLeftmostIdentifier(node: Node): Node { + if (node === leftmost) { + const type = getDeclaredTypeOfSymbol(sym!); + const name = sym!.flags & SymbolFlags.TypeParameter ? typeParameterToName(type, context) : factory.cloneNode(node as Identifier); + name.symbol = sym!; // for quickinfo, which uses identifier symbol information + return setTextRange(context, setEmitFlags(name, EmitFlags.NoAsciiEscaping), node); + } + const updated = visitEachChildWorker(node, c => attachSymbolToLeftmostIdentifier(c), /*context*/ undefined); + if (updated !== node) { + setTextRange(context, updated, node); + } + return updated; + } + } + + function serializeTypeName(context: NodeBuilderContext, node: EntityName, isTypeOf?: boolean, typeArguments?: readonly TypeNode[]) { + const meaning = isTypeOf ? SymbolFlags.Value : SymbolFlags.Type; + const symbol = resolveEntityName(node, meaning, /*ignoreErrors*/ true); + if (!symbol) return undefined; + const resolvedSymbol = symbol.flags & SymbolFlags.Alias ? resolveAlias(symbol) : symbol; + if (isSymbolAccessible(symbol, context.enclosingDeclaration, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible) return undefined; + return symbolToTypeNode(resolvedSymbol, context, meaning, typeArguments); + } + + function canReuseTypeNode(context: NodeBuilderContext, existing: TypeNode) { + if (isInJSFile(existing)) { + if (isLiteralImportTypeNode(existing)) { + // Ensure resolvedSymbol is present + void getTypeFromImportTypeNode(existing); + const nodeSymbol = getNodeLinks(existing).resolvedSymbol; + return ( + !nodeSymbol || + !( + // The import type resolved using jsdoc fallback logic + (!existing.isTypeOf && !(nodeSymbol.flags & SymbolFlags.Type)) || + // The import type had type arguments autofilled by js fallback logic + !(length(existing.typeArguments) >= getMinTypeArgumentCount(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(nodeSymbol))) + ) + ); + } + } + if (isThisTypeNode(existing)) { + if (context.mapper === undefined) return true; + const type = getTypeFromTypeNode(context, existing, /*noMappedTypes*/ true); + return !!type; + } + if (isTypeReferenceNode(existing)) { + if (isConstTypeReference(existing)) return false; + const type = getTypeFromTypeReference(existing); + const symbol = getNodeLinks(existing).resolvedSymbol; + if (!symbol) return false; + if (symbol.flags & SymbolFlags.TypeParameter) { + const type = getDeclaredTypeOfSymbol(symbol); + if (context.mapper && getMappedType(type, context.mapper) !== type) { + return false; + } + } + if (isInJSDoc(existing)) { + return existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing, type) + && !getIntendedTypeFromJSDocTypeReference(existing) // We should probably allow the reuse of JSDoc reference types such as String Number etc + && (symbol.flags & SymbolFlags.Type); // JSDoc type annotations can reference values (meaning typeof value) as well as types. We only reuse type nodes + } + } + if ( + isTypeOperatorNode(existing) && + existing.operator === SyntaxKind.UniqueKeyword && + existing.type.kind === SyntaxKind.SymbolKeyword + ) { + const effectiveEnclosingContext = context.enclosingDeclaration && getEnclosingDeclarationIgnoringFakeScope(context.enclosingDeclaration); + return !!findAncestor(existing, n => n === effectiveEnclosingContext); + } + return true; + } + + function serializeExistingTypeNode(context: NodeBuilderContext, typeNode: TypeNode) { + const type = getTypeFromTypeNode(context, typeNode); + return typeToTypeNodeHelper(type, context); + } + + /** + * Do you mean to call this directly? You probably should use `tryReuseExistingTypeNode` instead, + * which performs sanity checking on the type before doing this. + */ + function tryReuseExistingTypeNodeHelper(context: NodeBuilderContext, existing: TypeNode) { + if (cancellationToken && cancellationToken.throwIfCancellationRequested) { + cancellationToken.throwIfCancellationRequested(); + } + let hadError = false; + const { finalizeBoundary, startRecoveryScope } = createRecoveryBoundary(); + const transformed = visitNode(existing, visitExistingNodeTreeSymbols, isTypeNode); + if (!finalizeBoundary()) { + return undefined; + } + context.approximateLength += existing.end - existing.pos; + return transformed; + + function visitExistingNodeTreeSymbols(node: Node): Node | undefined { + // If there was an error in a sibling node bail early, the result will be discarded anyway + if (hadError) return node; + const recover = startRecoveryScope(); + const onExitNewScope = isNewScopeNode(node) ? onEnterNewScope(node) : undefined; + const result = visitExistingNodeTreeSymbolsWorker(node); + onExitNewScope?.(); + + // If there was an error, maybe we can recover by serializing the actual type of the node + if (hadError) { + if (isTypeNode(node) && !isTypePredicateNode(node)) { + recover(); + return serializeExistingTypeNode(context, node); + } + return node; + } + // We want to clone the subtree, so when we mark it up with __pos and __end in quickfixes, + // we don't get odd behavior because of reused nodes. We also need to clone to _remove_ + // the position information if the node comes from a different file than the one the node builder + // is set to build for (even though we are reusing the node structure, the position information + // would make the printer print invalid spans for literals and identifiers, and the formatter would + // choke on the mismatched positonal spans between a parent and an injected child from another file). + return result ? setTextRange(context, result, node) : undefined; + } + + function createRecoveryBoundary() { + let trackedSymbols: TrackedSymbol[]; + let unreportedErrors: (() => void)[]; + const oldTracker = context.tracker; + const oldTrackedSymbols = context.trackedSymbols; + context.trackedSymbols = undefined; + const oldEncounteredError = context.encounteredError; + context.tracker = new SymbolTrackerImpl(context, { + ...oldTracker.inner, + reportCyclicStructureError() { + markError(() => oldTracker.reportCyclicStructureError()); + }, + reportInaccessibleThisError() { + markError(() => oldTracker.reportInaccessibleThisError()); + }, + reportInaccessibleUniqueSymbolError() { + markError(() => oldTracker.reportInaccessibleUniqueSymbolError()); + }, + reportLikelyUnsafeImportRequiredError(specifier) { + markError(() => oldTracker.reportLikelyUnsafeImportRequiredError(specifier)); + }, + reportNonSerializableProperty(name) { + markError(() => oldTracker.reportNonSerializableProperty(name)); + }, + trackSymbol(sym, decl, meaning) { + (trackedSymbols ??= []).push([sym, decl, meaning]); + return false; + }, + moduleResolverHost: context.tracker.moduleResolverHost, + }, context.tracker.moduleResolverHost); + + return { + startRecoveryScope, + finalizeBoundary, + }; + + function markError(unreportedError: () => void) { + hadError = true; + (unreportedErrors ??= []).push(unreportedError); + } + + function startRecoveryScope() { + const trackedSymbolsTop = trackedSymbols?.length ?? 0; + const unreportedErrorsTop = unreportedErrors?.length ?? 0; + return () => { + hadError = false; + // Reset the tracked symbols to before the error + if (trackedSymbols) { + trackedSymbols.length = trackedSymbolsTop; + } + if (unreportedErrors) { + unreportedErrors.length = unreportedErrorsTop; + } + }; + } + + function finalizeBoundary() { + context.tracker = oldTracker; + context.trackedSymbols = oldTrackedSymbols; + context.encounteredError = oldEncounteredError; + + unreportedErrors?.forEach(fn => fn()); + if (hadError) { + return false; + } + trackedSymbols?.forEach( + ([symbol, enclosingDeclaration, meaning]) => + context.tracker.trackSymbol( + symbol, + enclosingDeclaration, + meaning, + ), + ); + return true; + } + } + function onEnterNewScope(node: IntroducesNewScopeNode | ConditionalTypeNode) { + return enterNewScope(context, node, getParametersInScope(node), getTypeParametersInScope(node)); + } + + function tryVisitSimpleTypeNode(node: TypeNode): TypeNode | undefined { + const innerNode = skipTypeParentheses(node); + switch (innerNode.kind) { + case SyntaxKind.TypeReference: + return tryVisitTypeReference(innerNode as TypeReferenceNode); + case SyntaxKind.TypeQuery: + return tryVisitTypeQuery(innerNode as TypeQueryNode); + case SyntaxKind.IndexedAccessType: + return tryVisitIndexedAccess(innerNode as IndexedAccessTypeNode); + case SyntaxKind.TypeOperator: + const typeOperatorNode = innerNode as TypeOperatorNode; + if (typeOperatorNode.operator === SyntaxKind.KeyOfKeyword) { + return tryVisitKeyOf(typeOperatorNode); + } + } + return visitNode(node, visitExistingNodeTreeSymbols, isTypeNode); + } + + function tryVisitIndexedAccess(node: IndexedAccessTypeNode): TypeNode | undefined { + const resultObjectType = tryVisitSimpleTypeNode(node.objectType); + if (resultObjectType === undefined) { + return undefined; + } + return factory.updateIndexedAccessTypeNode(node, resultObjectType, visitNode(node.indexType, visitExistingNodeTreeSymbols, isTypeNode)!); + } + + function tryVisitKeyOf(node: TypeOperatorNode): TypeNode | undefined { + Debug.assertEqual(node.operator, SyntaxKind.KeyOfKeyword); + const type = tryVisitSimpleTypeNode(node.type); + if (type === undefined) { + return undefined; + } + return factory.updateTypeOperatorNode(node, type); + } + + function tryVisitTypeQuery(node: TypeQueryNode): TypeNode | undefined { + const { introducesError, node: exprName } = trackExistingEntityName(node.exprName, context); + if (!introducesError) { + return factory.updateTypeQueryNode( + node, + exprName, + visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode), + ); + } + + const serializedName = serializeTypeName(context, node.exprName, /*isTypeOf*/ true); + if (serializedName) { + return setTextRange(context, serializedName, node.exprName); + } + } + + function tryVisitTypeReference(node: TypeReferenceNode): TypeNode | undefined { + if (canReuseTypeNode(context, node)) { + const { introducesError, node: newName } = trackExistingEntityName(node.typeName, context); + const typeArguments = visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode); + + if (!introducesError) { + const updated = factory.updateTypeReferenceNode( + node, + newName, + typeArguments, + ); + return setTextRange(context, updated, node); + } + else { + const serializedName = serializeTypeName(context, node.typeName, /*isTypeOf*/ false, typeArguments); + if (serializedName) { + return setTextRange(context, serializedName, node.typeName); + } + } + } + } + + function visitExistingNodeTreeSymbolsWorker(node: Node): Node | undefined { + if (isJSDocTypeExpression(node)) { + // Unwrap JSDocTypeExpressions + return visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode); + } + // We don't _actually_ support jsdoc namepath types, emit `any` instead + if (isJSDocAllType(node) || node.kind === SyntaxKind.JSDocNamepathType) { + return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + if (isJSDocUnknownType(node)) { + return factory.createKeywordTypeNode(SyntaxKind.UnknownKeyword); + } + if (isJSDocNullableType(node)) { + return factory.createUnionTypeNode([visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)!, factory.createLiteralTypeNode(factory.createNull())]); + } + if (isJSDocOptionalType(node)) { + return factory.createUnionTypeNode([visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)!, factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); + } + if (isJSDocNonNullableType(node)) { + return visitNode(node.type, visitExistingNodeTreeSymbols); + } + if (isJSDocVariadicType(node)) { + return factory.createArrayTypeNode(visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)!); + } + if (isJSDocTypeLiteral(node)) { + return factory.createTypeLiteralNode(map(node.jsDocPropertyTags, t => { + const name = visitNode(isIdentifier(t.name) ? t.name : t.name.right, visitExistingNodeTreeSymbols, isIdentifier)!; + const typeViaParent = getTypeOfPropertyOfType(getTypeFromTypeNode(context, node), name.escapedText); + const overrideTypeNode = typeViaParent && t.typeExpression && getTypeFromTypeNode(context, t.typeExpression.type) !== typeViaParent ? typeToTypeNodeHelper(typeViaParent, context) : undefined; + + return factory.createPropertySignature( + /*modifiers*/ undefined, + name, + t.isBracketed || t.typeExpression && isJSDocOptionalType(t.typeExpression.type) ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + overrideTypeNode || (t.typeExpression && visitNode(t.typeExpression.type, visitExistingNodeTreeSymbols, isTypeNode)) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), + ); + })); + } + if (isTypeReferenceNode(node) && isIdentifier(node.typeName) && node.typeName.escapedText === "") { + return setOriginalNode(factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), node); + } + if ((isExpressionWithTypeArguments(node) || isTypeReferenceNode(node)) && isJSDocIndexSignature(node)) { + return factory.createTypeLiteralNode([factory.createIndexSignature( + /*modifiers*/ undefined, + [factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + "x", + /*questionToken*/ undefined, + visitNode(node.typeArguments![0], visitExistingNodeTreeSymbols, isTypeNode), + )], + visitNode(node.typeArguments![1], visitExistingNodeTreeSymbols, isTypeNode), + )]); + } + if (isJSDocFunctionType(node)) { + if (isJSDocConstructSignature(node)) { + let newTypeNode: TypeNode | undefined; + return factory.createConstructorTypeNode( + /*modifiers*/ undefined, + visitNodes(node.typeParameters, visitExistingNodeTreeSymbols, isTypeParameterDeclaration), + mapDefined(node.parameters, (p, i) => + p.name && isIdentifier(p.name) && p.name.escapedText === "new" ? (newTypeNode = p.type, undefined) : factory.createParameterDeclaration( + /*modifiers*/ undefined, + getEffectiveDotDotDotForParameter(p), + setTextRange(context, factory.createIdentifier(getNameForJSDocFunctionParameter(p, i)), p), + factory.cloneNode(p.questionToken), + visitNode(p.type, visitExistingNodeTreeSymbols, isTypeNode), + /*initializer*/ undefined, + )), + visitNode(newTypeNode || node.type, visitExistingNodeTreeSymbols, isTypeNode) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), + ); + } + else { + return factory.createFunctionTypeNode( + visitNodes(node.typeParameters, visitExistingNodeTreeSymbols, isTypeParameterDeclaration), + map(node.parameters, (p, i) => + factory.createParameterDeclaration( + /*modifiers*/ undefined, + getEffectiveDotDotDotForParameter(p), + setTextRange(context, factory.createIdentifier(getNameForJSDocFunctionParameter(p, i)), p), + factory.cloneNode(p.questionToken), + visitNode(p.type, visitExistingNodeTreeSymbols, isTypeNode), + /*initializer*/ undefined, + )), + visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), + ); + } + } + if (isThisTypeNode(node)) { + if (canReuseTypeNode(context, node)) { + return node; + } + hadError = true; + return node; + } + if (isTypeParameterDeclaration(node)) { + return factory.updateTypeParameterDeclaration( + node, + visitNodes(node.modifiers, visitExistingNodeTreeSymbols, isModifier), + setTextRange(context, typeParameterToName(getDeclaredTypeOfSymbol(getSymbolOfDeclaration(node)), context), node), + visitNode(node.constraint, visitExistingNodeTreeSymbols, isTypeNode), + visitNode(node.default, visitExistingNodeTreeSymbols, isTypeNode), + ); + } + + if (isIndexedAccessTypeNode(node)) { + const result = tryVisitIndexedAccess(node); + if (!result) { + hadError = true; + return node; + } + return result; + } + + if (isTypeReferenceNode(node)) { + const result = tryVisitTypeReference(node); + if (result) { + return result; + } + hadError = true; + return node; + } + if (isLiteralImportTypeNode(node)) { + const nodeSymbol = getNodeLinks(node).resolvedSymbol; + if ( + isInJSDoc(node) && + nodeSymbol && + ( + // The import type resolved using jsdoc fallback logic + (!node.isTypeOf && !(nodeSymbol.flags & SymbolFlags.Type)) || + // The import type had type arguments autofilled by js fallback logic + !(length(node.typeArguments) >= getMinTypeArgumentCount(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(nodeSymbol))) + ) + ) { + return setTextRange(context, typeToTypeNodeHelper(getTypeFromTypeNode(context, node), context), node); + } + return factory.updateImportTypeNode( + node, + factory.updateLiteralTypeNode(node.argument, rewriteModuleSpecifier(node, node.argument.literal)), + visitNode(node.attributes, visitExistingNodeTreeSymbols, isImportAttributes), + visitNode(node.qualifier, visitExistingNodeTreeSymbols, isEntityName), + visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode), + node.isTypeOf, + ); + } + if (isNamedDeclaration(node) && node.name.kind === SyntaxKind.ComputedPropertyName && !isLateBindableName(node.name)) { + if (!(context.flags & NodeBuilderFlags.AllowUnresolvedNames && hasDynamicName(node) && isEntityNameExpression(node.name.expression) && checkComputedPropertyName(node.name).flags & TypeFlags.Any)) { + return undefined; + } + } + if ( + (isFunctionLike(node) && !node.type) + || (isPropertyDeclaration(node) && !node.type && !node.initializer) + || (isPropertySignature(node) && !node.type && !node.initializer) + || (isParameter(node) && !node.type && !node.initializer) + ) { + let visited = visitEachChild(node, visitExistingNodeTreeSymbols); + if (visited === node) { + visited = setTextRange(context, factory.cloneNode(node), node); + } + (visited as Mutable).type = factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + if (isParameter(node)) { + (visited as Mutable).modifiers = undefined; + } + return visited; + } + if (isTypeQueryNode(node)) { + const result = tryVisitTypeQuery(node); + if (!result) { + hadError = true; + return node; + } + return result; + } + if (isComputedPropertyName(node) && isEntityNameExpression(node.expression)) { + const { node: result, introducesError } = trackExistingEntityName(node.expression, context); + if (!introducesError) { + return factory.updateComputedPropertyName(node, result); + } + else { + const type = getWidenedType(getRegularTypeOfExpression(node.expression)); + const computedPropertyNameType = typeToTypeNodeHelper(type, context); + let literal; + if (isLiteralTypeNode(computedPropertyNameType)) { + literal = computedPropertyNameType.literal; + } + else { + const evaluated = evaluateEntityNameExpression(node.expression); + const literalNode = typeof evaluated.value === "string" ? factory.createStringLiteral(evaluated.value, /*isSingleQuote*/ undefined) : + typeof evaluated.value === "number" ? factory.createNumericLiteral(evaluated.value, /*numericLiteralFlags*/ 0) : + undefined; + if (!literalNode) { + if (isImportTypeNode(computedPropertyNameType)) { + trackComputedName(node.expression, context.enclosingDeclaration, context); + } + return node; + } + literal = literalNode; + } + if (literal.kind === SyntaxKind.StringLiteral && isIdentifierText(literal.text, getEmitScriptTarget(compilerOptions))) { + return factory.createIdentifier(literal.text); + } + if (literal.kind === SyntaxKind.NumericLiteral && !literal.text.startsWith("-")) { + return literal; + } + return factory.updateComputedPropertyName(node, literal); + } + } + if (isTypePredicateNode(node)) { + let parameterName; + if (isIdentifier(node.parameterName)) { + const { node: result, introducesError } = trackExistingEntityName(node.parameterName, context); + // Should not usually happen the only case is when a type predicate comes from a JSDoc type annotation with it's own parameter symbol definition. + // /** @type {(v: unknown) => v is undefined} */ + // const isUndef = v => v === undefined; + hadError = hadError || introducesError; + parameterName = result; + } + else { + parameterName = factory.cloneNode(node.parameterName); + } + return factory.updateTypePredicateNode(node, factory.cloneNode(node.assertsModifier), parameterName, visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)); + } + + if (isTupleTypeNode(node) || isTypeLiteralNode(node) || isMappedTypeNode(node)) { + const visited = visitEachChild(node, visitExistingNodeTreeSymbols); + const clone = setTextRange(context, visited === node ? factory.cloneNode(node) : visited, node); + const flags = getEmitFlags(clone); + setEmitFlags(clone, flags | (context.flags & NodeBuilderFlags.MultilineObjectLiterals && isTypeLiteralNode(node) ? 0 : EmitFlags.SingleLine)); + return clone; + } + if (isStringLiteral(node) && !!(context.flags & NodeBuilderFlags.UseSingleQuotesForStringLiteralType) && !node.singleQuote) { + const clone = factory.cloneNode(node); + (clone as Mutable).singleQuote = true; + return clone; + } + if (isConditionalTypeNode(node)) { + const checkType = visitNode(node.checkType, visitExistingNodeTreeSymbols, isTypeNode)!; + + const disposeScope = onEnterNewScope(node); + const extendType = visitNode(node.extendsType, visitExistingNodeTreeSymbols, isTypeNode)!; + const trueType = visitNode(node.trueType, visitExistingNodeTreeSymbols, isTypeNode)!; + disposeScope(); + const falseType = visitNode(node.falseType, visitExistingNodeTreeSymbols, isTypeNode)!; + return factory.updateConditionalTypeNode( + node, + checkType, + extendType, + trueType, + falseType, + ); + } + + if (isTypeOperatorNode(node)) { + if (node.operator === SyntaxKind.UniqueKeyword && node.type.kind === SyntaxKind.SymbolKeyword) { + if (!canReuseTypeNode(context, node)) { + hadError = true; + return node; + } + } + else if (node.operator === SyntaxKind.KeyOfKeyword) { + const result = tryVisitKeyOf(node); + if (!result) { + hadError = true; + return node; + } + return result; + } + } + + return visitEachChild(node, visitExistingNodeTreeSymbols); + + function visitEachChild(node: T, visitor: Visitor): T; + function visitEachChild(node: T | undefined, visitor: Visitor): T | undefined; + function visitEachChild(node: T | undefined, visitor: Visitor): T | undefined { + const nonlocalNode = !context.enclosingFile || context.enclosingFile !== getSourceFileOfNode(node); + return visitEachChildWorker(node, visitor, /*context*/ undefined, nonlocalNode ? visitNodesWithoutCopyingPositions : undefined); + } + + function visitNodesWithoutCopyingPositions( + nodes: NodeArray | undefined, + visitor: Visitor, + test?: (node: Node) => boolean, + start?: number, + count?: number, + ): NodeArray | undefined { + let result = visitNodes(nodes, visitor, test, start, count); + if (result) { + if (result.pos !== -1 || result.end !== -1) { + if (result === nodes) { + result = factory.createNodeArray(nodes, nodes.hasTrailingComma); + } + setTextRangePosEnd(result, -1, -1); + } + } + return result; + } + + function getEffectiveDotDotDotForParameter(p: ParameterDeclaration) { + return p.dotDotDotToken || (p.type && isJSDocVariadicType(p.type) ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined); + } + + /** Note that `new:T` parameters are not handled, but should be before calling this function. */ + function getNameForJSDocFunctionParameter(p: ParameterDeclaration, index: number) { + return p.name && isIdentifier(p.name) && p.name.escapedText === "this" ? "this" + : getEffectiveDotDotDotForParameter(p) ? `args` + : `arg${index}`; + } + + function rewriteModuleSpecifier(parent: ImportTypeNode, lit: StringLiteral) { + if (context.bundled || context.enclosingFile !== getSourceFileOfNode(lit)) { + let name = lit.text; + const nodeSymbol = getNodeLinks(node).resolvedSymbol; + const meaning = parent.isTypeOf ? SymbolFlags.Value : SymbolFlags.Type; + const parentSymbol = nodeSymbol + && isSymbolAccessible(nodeSymbol, context.enclosingDeclaration, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility === SymbolAccessibility.Accessible + && lookupSymbolChain(nodeSymbol, context, meaning, /*yieldModuleSymbol*/ true)[0]; + if (parentSymbol && isExternalModuleSymbol(parentSymbol)) { + name = getSpecifierForModuleSymbol(parentSymbol, context); + } + else { + const targetFile = getExternalModuleFileFromDeclaration(parent); + if (targetFile) { + name = getSpecifierForModuleSymbol(targetFile.symbol, context); + } + } + if (name.includes("/node_modules/")) { + context.encounteredError = true; + if (context.tracker.reportLikelyUnsafeImportRequiredError) { + context.tracker.reportLikelyUnsafeImportRequiredError(name); + } + } + if (name !== lit.text) { + return setOriginalNode(factory.createStringLiteral(name), lit); + } + } + return visitNode(lit, visitExistingNodeTreeSymbols, isStringLiteral)!; + } + } + } + + function symbolTableToDeclarationStatements(symbolTable: SymbolTable, context: NodeBuilderContext): Statement[] { + const serializePropertySymbolForClass = makeSerializePropertySymbol(factory.createPropertyDeclaration, SyntaxKind.MethodDeclaration, /*useAccessors*/ true); + const serializePropertySymbolForInterfaceWorker = makeSerializePropertySymbol((mods, name, question, type) => factory.createPropertySignature(mods, name, question, type), SyntaxKind.MethodSignature, /*useAccessors*/ false); + + // TODO: Use `setOriginalNode` on original declaration names where possible so these declarations see some kind of + // declaration mapping + + // We save the enclosing declaration off here so it's not adjusted by well-meaning declaration + // emit codepaths which want to apply more specific contexts (so we can still refer to the root real declaration + // we're trying to emit from later on) + const enclosingDeclaration = context.enclosingDeclaration!; + let results: Statement[] = []; + const visitedSymbols = new Set(); + const deferredPrivatesStack: Map[] = []; + const oldcontext = context; + context = { + ...oldcontext, + usedSymbolNames: new Set(oldcontext.usedSymbolNames), + remappedSymbolNames: new Map(), + remappedSymbolReferences: new Map(oldcontext.remappedSymbolReferences?.entries()), + tracker: undefined!, + }; + const tracker: SymbolTracker = { + ...oldcontext.tracker.inner, + trackSymbol: (sym, decl, meaning) => { + if (context.remappedSymbolNames?.has(getSymbolId(sym))) return false; // If the context has a remapped name for the symbol, it *should* mean it's been made visible + const accessibleResult = isSymbolAccessible(sym, decl, meaning, /*shouldComputeAliasesToMakeVisible*/ false); + if (accessibleResult.accessibility === SymbolAccessibility.Accessible) { + // Lookup the root symbol of the chain of refs we'll use to access it and serialize it + const chain = lookupSymbolChainWorker(sym, context, meaning); + if (!(sym.flags & SymbolFlags.Property)) { + // Only include referenced privates in the same file. Weird JS aliases may expose privates + // from other files - assume JS transforms will make those available via expected means + const root = chain[0]; + const contextFile = getSourceFileOfNode(oldcontext.enclosingDeclaration); + if (some(root.declarations, d => getSourceFileOfNode(d) === contextFile)) { + includePrivateSymbol(root); + } + } + } + else if (oldcontext.tracker.inner?.trackSymbol) { + return oldcontext.tracker.inner.trackSymbol(sym, decl, meaning); + } + return false; + }, + }; + context.tracker = new SymbolTrackerImpl(context, tracker, oldcontext.tracker.moduleResolverHost); + forEachEntry(symbolTable, (symbol, name) => { + const baseName = unescapeLeadingUnderscores(name); + void getInternalSymbolName(symbol, baseName); // Called to cache values into `usedSymbolNames` and `remappedSymbolNames` + }); + let addingDeclare = !context.bundled; + const exportEquals = symbolTable.get(InternalSymbolName.ExportEquals); + if (exportEquals && symbolTable.size > 1 && exportEquals.flags & (SymbolFlags.Alias | SymbolFlags.Module)) { + symbolTable = createSymbolTable(); + // Remove extraneous elements from root symbol table (they'll be mixed back in when the target of the `export=` is looked up) + symbolTable.set(InternalSymbolName.ExportEquals, exportEquals); + } + + visitSymbolTable(symbolTable); + return mergeRedundantStatements(results); + + function isIdentifierAndNotUndefined(node: Node | undefined): node is Identifier { + return !!node && node.kind === SyntaxKind.Identifier; + } + + function getNamesOfDeclaration(statement: Statement): Identifier[] { + if (isVariableStatement(statement)) { + return filter(map(statement.declarationList.declarations, getNameOfDeclaration), isIdentifierAndNotUndefined); + } + return filter([getNameOfDeclaration(statement as DeclarationStatement)], isIdentifierAndNotUndefined); + } + + function flattenExportAssignedNamespace(statements: Statement[]) { + const exportAssignment = find(statements, isExportAssignment); + const nsIndex = findIndex(statements, isModuleDeclaration); + let ns = nsIndex !== -1 ? statements[nsIndex] as ModuleDeclaration : undefined; + if ( + ns && exportAssignment && exportAssignment.isExportEquals && + isIdentifier(exportAssignment.expression) && isIdentifier(ns.name) && idText(ns.name) === idText(exportAssignment.expression) && + ns.body && isModuleBlock(ns.body) + ) { + // Pass 0: Correct situations where a module has both an `export = ns` and multiple top-level exports by stripping the export modifiers from + // the top-level exports and exporting them in the targeted ns, as can occur when a js file has both typedefs and `module.export` assignments + const excessExports = filter(statements, s => !!(getEffectiveModifierFlags(s) & ModifierFlags.Export)); + const name = ns.name; + let body = ns.body; + if (length(excessExports)) { + ns = factory.updateModuleDeclaration( + ns, + ns.modifiers, + ns.name, + body = factory.updateModuleBlock( + body, + factory.createNodeArray([ + ...ns.body.statements, + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(map(flatMap(excessExports, e => getNamesOfDeclaration(e)), id => factory.createExportSpecifier(/*isTypeOnly*/ false, /*propertyName*/ undefined, id))), + /*moduleSpecifier*/ undefined, + ), + ]), + ), + ); + statements = [...statements.slice(0, nsIndex), ns, ...statements.slice(nsIndex + 1)]; + } + + // Pass 1: Flatten `export namespace _exports {} export = _exports;` so long as the `export=` only points at a single namespace declaration + if (!find(statements, s => s !== ns && nodeHasName(s, name))) { + results = []; + // If the namespace contains no export assignments or declarations, and no declarations flagged with `export`, then _everything_ is exported - + // to respect this as the top level, we need to add an `export` modifier to everything + const mixinExportFlag = !some(body.statements, s => hasSyntacticModifier(s, ModifierFlags.Export) || isExportAssignment(s) || isExportDeclaration(s)); + forEach(body.statements, s => { + addResult(s, mixinExportFlag ? ModifierFlags.Export : ModifierFlags.None); // Recalculates the ambient (and export, if applicable from above) flag + }); + statements = [...filter(statements, s => s !== ns && s !== exportAssignment), ...results]; + } + } + return statements; + } + + function mergeExportDeclarations(statements: Statement[]) { + // Pass 2: Combine all `export {}` declarations + const exports = filter(statements, d => isExportDeclaration(d) && !d.moduleSpecifier && !!d.exportClause && isNamedExports(d.exportClause)) as ExportDeclaration[]; + if (length(exports) > 1) { + const nonExports = filter(statements, d => !isExportDeclaration(d) || !!d.moduleSpecifier || !d.exportClause); + statements = [ + ...nonExports, + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(flatMap(exports, e => cast(e.exportClause, isNamedExports).elements)), + /*moduleSpecifier*/ undefined, + ), + ]; + } + // Pass 2b: Also combine all `export {} from "..."` declarations as needed + const reexports = filter(statements, d => isExportDeclaration(d) && !!d.moduleSpecifier && !!d.exportClause && isNamedExports(d.exportClause)) as ExportDeclaration[]; + if (length(reexports) > 1) { + const groups = group(reexports, decl => isStringLiteral(decl.moduleSpecifier!) ? ">" + decl.moduleSpecifier.text : ">"); + if (groups.length !== reexports.length) { + for (const group of groups) { + if (group.length > 1) { + // remove group members from statements and then merge group members and add back to statements + statements = [ + ...filter(statements, s => !group.includes(s as ExportDeclaration)), + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(flatMap(group, e => cast(e.exportClause, isNamedExports).elements)), + group[0].moduleSpecifier, + ), + ]; + } + } + } + } + return statements; + } + + function inlineExportModifiers(statements: Statement[]) { + // Pass 3: Move all `export {}`'s to `export` modifiers where possible + const index = findIndex(statements, d => isExportDeclaration(d) && !d.moduleSpecifier && !d.attributes && !!d.exportClause && isNamedExports(d.exportClause)); + if (index >= 0) { + const exportDecl = statements[index] as ExportDeclaration & { readonly exportClause: NamedExports; }; + const replacements = mapDefined(exportDecl.exportClause.elements, e => { + if (!e.propertyName && e.name.kind !== SyntaxKind.StringLiteral) { + // export {name} - look thru `statements` for `name`, and if all results can take an `export` modifier, do so and filter it + const name = e.name; + const indices = indicesOf(statements); + const associatedIndices = filter(indices, i => nodeHasName(statements[i], name)); + if (length(associatedIndices) && every(associatedIndices, i => canHaveExportModifier(statements[i]))) { + for (const index of associatedIndices) { + statements[index] = addExportModifier(statements[index] as Extract); + } + return undefined; + } + } + return e; + }); + if (!length(replacements)) { + // all clauses removed, remove the export declaration + orderedRemoveItemAt(statements, index); + } + else { + // some items filtered, others not - update the export declaration + statements[index] = factory.updateExportDeclaration( + exportDecl, + exportDecl.modifiers, + exportDecl.isTypeOnly, + factory.updateNamedExports( + exportDecl.exportClause, + replacements, + ), + exportDecl.moduleSpecifier, + exportDecl.attributes, + ); + } + } + return statements; + } + + function mergeRedundantStatements(statements: Statement[]) { + statements = flattenExportAssignedNamespace(statements); + statements = mergeExportDeclarations(statements); + statements = inlineExportModifiers(statements); + + // Not a cleanup, but as a final step: If there is a mix of `export` and non-`export` declarations, but no `export =` or `export {}` add a `export {};` so + // declaration privacy is respected. + if ( + enclosingDeclaration && + ((isSourceFile(enclosingDeclaration) && isExternalOrCommonJsModule(enclosingDeclaration)) || isModuleDeclaration(enclosingDeclaration)) && + (!some(statements, isExternalModuleIndicator) || (!hasScopeMarker(statements) && some(statements, needsScopeMarker))) + ) { + statements.push(createEmptyExports(factory)); + } + return statements; + } + + function addExportModifier(node: Extract) { + const flags = (getEffectiveModifierFlags(node) | ModifierFlags.Export) & ~ModifierFlags.Ambient; + return factory.replaceModifiers(node, flags); + } + + function removeExportModifier(node: Extract) { + const flags = getEffectiveModifierFlags(node) & ~ModifierFlags.Export; + return factory.replaceModifiers(node, flags); + } + + function visitSymbolTable(symbolTable: SymbolTable, suppressNewPrivateContext?: boolean, propertyAsAlias?: boolean) { + if (!suppressNewPrivateContext) { + deferredPrivatesStack.push(new Map()); + } + symbolTable.forEach((symbol: Symbol) => { + serializeSymbol(symbol, /*isPrivate*/ false, !!propertyAsAlias); + }); + if (!suppressNewPrivateContext) { + // deferredPrivates will be filled up by visiting the symbol table + // And will continue to iterate as elements are added while visited `deferredPrivates` + // (As that's how a map iterator is defined to work) + deferredPrivatesStack[deferredPrivatesStack.length - 1].forEach((symbol: Symbol) => { + serializeSymbol(symbol, /*isPrivate*/ true, !!propertyAsAlias); + }); + deferredPrivatesStack.pop(); + } + } + + function serializeSymbol(symbol: Symbol, isPrivate: boolean, propertyAsAlias: boolean): void { + void getPropertiesOfType(getTypeOfSymbol(symbol)); // resolve symbol's type and properties, which should trigger any required merges + // cache visited list based on merged symbol, since we want to use the unmerged top-level symbol, but + // still skip reserializing it if we encounter the merged product later on + const visitedSym = getMergedSymbol(symbol); + if (visitedSymbols.has(getSymbolId(visitedSym))) { + return; // Already printed + } + visitedSymbols.add(getSymbolId(visitedSym)); + // Only actually serialize symbols within the correct enclosing declaration, otherwise do nothing with the out-of-context symbol + const skipMembershipCheck = !isPrivate; // We only call this on exported symbols when we know they're in the correct scope + if (skipMembershipCheck || (!!length(symbol.declarations) && some(symbol.declarations, d => !!findAncestor(d, n => n === enclosingDeclaration)))) { + const scopeCleanup = cloneNodeBuilderContext(context); + serializeSymbolWorker(symbol, isPrivate, propertyAsAlias); + scopeCleanup(); + } + } + + // Synthesize declarations for a symbol - might be an Interface, a Class, a Namespace, a Type, a Variable (const, let, or var), an Alias + // or a merge of some number of those. + // An interesting challenge is ensuring that when classes merge with namespaces and interfaces, is keeping + // each symbol in only one of the representations + // Also, synthesizing a default export of some kind + // If it's an alias: emit `export default ref` + // If it's a property: emit `export default _default` with a `_default` prop + // If it's a class/interface/function: emit a class/interface/function with a `default` modifier + // These forms can merge, eg (`export default 12; export default interface A {}`) + function serializeSymbolWorker(symbol: Symbol, isPrivate: boolean, propertyAsAlias: boolean, escapedSymbolName = symbol.escapedName): void { + const symbolName = unescapeLeadingUnderscores(escapedSymbolName); + const isDefault = escapedSymbolName === InternalSymbolName.Default; + if (isPrivate && !(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier) && isStringANonContextualKeyword(symbolName) && !isDefault) { + // Oh no. We cannot use this symbol's name as it's name... It's likely some jsdoc had an invalid name like `export` or `default` :( + context.encounteredError = true; + // TODO: Issue error via symbol tracker? + return; // If we need to emit a private with a keyword name, we're done for, since something else will try to refer to it by that name + } + let needsPostExportDefault = isDefault && !!( + symbol.flags & SymbolFlags.ExportDoesNotSupportDefaultModifier + || (symbol.flags & SymbolFlags.Function && length(getPropertiesOfType(getTypeOfSymbol(symbol)))) + ) && !(symbol.flags & SymbolFlags.Alias); // An alias symbol should preclude needing to make an alias ourselves + let needsExportDeclaration = !needsPostExportDefault && !isPrivate && isStringANonContextualKeyword(symbolName) && !isDefault; + // `serializeVariableOrProperty` will handle adding the export declaration if it is run (since `getInternalSymbolName` will create the name mapping), so we need to ensuer we unset `needsExportDeclaration` if it is + if (needsPostExportDefault || needsExportDeclaration) { + isPrivate = true; + } + const modifierFlags = (!isPrivate ? ModifierFlags.Export : 0) | (isDefault && !needsPostExportDefault ? ModifierFlags.Default : 0); + const isConstMergedWithNS = symbol.flags & SymbolFlags.Module && + symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.FunctionScopedVariable | SymbolFlags.Property) && + escapedSymbolName !== InternalSymbolName.ExportEquals; + const isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol); + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method) || isConstMergedWithNSPrintableAsSignatureMerge) { + serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + if (symbol.flags & SymbolFlags.TypeAlias) { + serializeTypeAlias(symbol, symbolName, modifierFlags); + } + // Need to skip over export= symbols below - json source files get a single `Property` flagged + // symbol of name `export=` which needs to be handled like an alias. It's not great, but it is what it is. + if ( + symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.FunctionScopedVariable | SymbolFlags.Property | SymbolFlags.Accessor) + && escapedSymbolName !== InternalSymbolName.ExportEquals + && !(symbol.flags & SymbolFlags.Prototype) + && !(symbol.flags & SymbolFlags.Class) + && !(symbol.flags & SymbolFlags.Method) + && !isConstMergedWithNSPrintableAsSignatureMerge + ) { + if (propertyAsAlias) { + const createdExport = serializeMaybeAliasAssignment(symbol); + if (createdExport) { + needsExportDeclaration = false; + needsPostExportDefault = false; + } + } + else { + const type = getTypeOfSymbol(symbol); + const localName = getInternalSymbolName(symbol, symbolName); + if (type.symbol && type.symbol !== symbol && type.symbol.flags & SymbolFlags.Function && some(type.symbol.declarations, isFunctionExpressionOrArrowFunction) && (type.symbol.members?.size || type.symbol.exports?.size)) { + // assignment of a anonymous expando/class-like function, the func/ns/merge branch below won't trigger, + // and the assignment form has to reference the unreachable anonymous type so will error. + // Instead, serialize the type's symbol, but with the current symbol's name, rather than the anonymous one. + if (!context.remappedSymbolReferences) { + context.remappedSymbolReferences = new Map(); + } + context.remappedSymbolReferences.set(getSymbolId(type.symbol), symbol); // save name remapping as local name for target symbol + serializeSymbolWorker(type.symbol, isPrivate, propertyAsAlias, escapedSymbolName); + context.remappedSymbolReferences.delete(getSymbolId(type.symbol)); + } + else if (!(symbol.flags & SymbolFlags.Function) && isTypeRepresentableAsFunctionNamespaceMerge(type, symbol)) { + // If the type looks like a function declaration + ns could represent it, and it's type is sourced locally, rewrite it into a function declaration + ns + serializeAsFunctionNamespaceMerge(type, symbol, localName, modifierFlags); + } + else { + // A Class + Property merge is made for a `module.exports.Member = class {}`, and it doesn't serialize well as either a class _or_ a property symbol - in fact, _it behaves like an alias!_ + // `var` is `FunctionScopedVariable`, `const` and `let` are `BlockScopedVariable`, and `module.exports.thing =` is `Property` + const flags = !(symbol.flags & SymbolFlags.BlockScopedVariable) + ? symbol.parent?.valueDeclaration && isSourceFile(symbol.parent?.valueDeclaration) + ? NodeFlags.Const // exports are immutable in es6, which is what we emulate and check; so it's safe to mark all exports as `const` (there's no difference to consumers, but it allows unique symbol type declarations) + : undefined + : isConstantVariable(symbol) + ? NodeFlags.Const + : NodeFlags.Let; + const name = (needsPostExportDefault || !(symbol.flags & SymbolFlags.Property)) ? localName : getUnusedName(localName, symbol); + let textRange: Node | undefined = symbol.declarations && find(symbol.declarations, d => isVariableDeclaration(d)); + if (textRange && isVariableDeclarationList(textRange.parent) && textRange.parent.declarations.length === 1) { + textRange = textRange.parent.parent; + } + const propertyAccessRequire = symbol.declarations?.find(isPropertyAccessExpression); + if ( + propertyAccessRequire && isBinaryExpression(propertyAccessRequire.parent) && isIdentifier(propertyAccessRequire.parent.right) + && type.symbol?.valueDeclaration && isSourceFile(type.symbol.valueDeclaration) + ) { + const alias = localName === propertyAccessRequire.parent.right.escapedText ? undefined : propertyAccessRequire.parent.right; + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, alias, localName)]), + ), + ModifierFlags.None, + ); + context.tracker.trackSymbol(type.symbol, context.enclosingDeclaration, SymbolFlags.Value); + } + else { + const statement = setTextRange( + context, + factory.createVariableStatement( + /*modifiers*/ undefined, + factory.createVariableDeclarationList([ + factory.createVariableDeclaration(name, /*exclamationToken*/ undefined, serializeTypeForDeclaration(context, /*declaration*/ undefined, type, symbol)), + ], flags), + ), + textRange, + ); + addResult(statement, name !== localName ? modifierFlags & ~ModifierFlags.Export : modifierFlags); + if (name !== localName && !isPrivate) { + // We rename the variable declaration we generate for Property symbols since they may have a name which + // conflicts with a local declaration. For example, given input: + // ``` + // function g() {} + // module.exports.g = g + // ``` + // In such a situation, we have a local variable named `g`, and a separate exported variable named `g`. + // Naively, we would emit + // ``` + // function g() {} + // export const g: typeof g; + // ``` + // That's obviously incorrect - the `g` in the type annotation needs to refer to the local `g`, but + // the export declaration shadows it. + // To work around that, we instead write + // ``` + // function g() {} + // const g_1: typeof g; + // export { g_1 as g }; + // ``` + // To create an export named `g` that does _not_ shadow the local `g` + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, name, localName)]), + ), + ModifierFlags.None, + ); + needsExportDeclaration = false; + needsPostExportDefault = false; + } + } + } + } + } + if (symbol.flags & SymbolFlags.Enum) { + serializeEnum(symbol, symbolName, modifierFlags); + } + if (symbol.flags & SymbolFlags.Class) { + if ( + symbol.flags & SymbolFlags.Property + && symbol.valueDeclaration + && isBinaryExpression(symbol.valueDeclaration.parent) + && isClassExpression(symbol.valueDeclaration.parent.right) + ) { + // Looks like a `module.exports.Sub = class {}` - if we serialize `symbol` as a class, the result will have no members, + // since the classiness is actually from the target of the effective alias the symbol is. yes. A BlockScopedVariable|Class|Property + // _really_ acts like an Alias, and none of a BlockScopedVariable, Class, or Property. This is the travesty of JS binding today. + serializeAsAlias(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + else { + serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + } + if ((symbol.flags & (SymbolFlags.ValueModule | SymbolFlags.NamespaceModule) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) { + serializeModule(symbol, symbolName, modifierFlags); + } + // The class meaning serialization should handle serializing all interface members + if (symbol.flags & SymbolFlags.Interface && !(symbol.flags & SymbolFlags.Class)) { + serializeInterface(symbol, symbolName, modifierFlags); + } + if (symbol.flags & SymbolFlags.Alias) { + serializeAsAlias(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + if (symbol.flags & SymbolFlags.Property && symbol.escapedName === InternalSymbolName.ExportEquals) { + serializeMaybeAliasAssignment(symbol); + } + if (symbol.flags & SymbolFlags.ExportStar) { + // synthesize export * from "moduleReference" + // Straightforward - only one thing to do - make an export declaration + if (symbol.declarations) { + for (const node of symbol.declarations) { + const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!); + if (!resolvedModule) continue; + addResult(factory.createExportDeclaration(/*modifiers*/ undefined, /*isTypeOnly*/ (node as ExportDeclaration).isTypeOnly, /*exportClause*/ undefined, factory.createStringLiteral(getSpecifierForModuleSymbol(resolvedModule, context))), ModifierFlags.None); + } + } + } + if (needsPostExportDefault) { + addResult(factory.createExportAssignment(/*modifiers*/ undefined, /*isExportEquals*/ false, factory.createIdentifier(getInternalSymbolName(symbol, symbolName))), ModifierFlags.None); + } + else if (needsExportDeclaration) { + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, getInternalSymbolName(symbol, symbolName), symbolName)]), + ), + ModifierFlags.None, + ); + } + } + + function includePrivateSymbol(symbol: Symbol) { + if (some(symbol.declarations, isPartOfParameterDeclaration)) return; + Debug.assertIsDefined(deferredPrivatesStack[deferredPrivatesStack.length - 1]); + getUnusedName(unescapeLeadingUnderscores(symbol.escapedName), symbol); // Call to cache unique name for symbol + // Blanket moving (import) aliases into the root private context should work, since imports are not valid within namespaces + // (so they must have been in the root to begin with if they were real imports) cjs `require` aliases (an upcoming feature) + // will throw a wrench in this, since those may have been nested, but we'll need to synthesize them in the outer scope + // anyway, as that's the only place the import they translate to is valid. In such a case, we might need to use a unique name + // for the moved import; which hopefully the above `getUnusedName` call should produce. + const isExternalImportAlias = !!(symbol.flags & SymbolFlags.Alias) && !some(symbol.declarations, d => + !!findAncestor(d, isExportDeclaration) || + isNamespaceExport(d) || + (isImportEqualsDeclaration(d) && !isExternalModuleReference(d.moduleReference))); + deferredPrivatesStack[isExternalImportAlias ? 0 : (deferredPrivatesStack.length - 1)].set(getSymbolId(symbol), symbol); + } + + function isExportingScope(enclosingDeclaration: Node) { + return ((isSourceFile(enclosingDeclaration) && (isExternalOrCommonJsModule(enclosingDeclaration) || isJsonSourceFile(enclosingDeclaration))) || + (isAmbientModule(enclosingDeclaration) && !isGlobalScopeAugmentation(enclosingDeclaration))); + } + + // Prepends a `declare` and/or `export` modifier if the context requires it, and then adds `node` to `result` and returns `node` + function addResult(node: Statement, additionalModifierFlags: ModifierFlags) { + if (canHaveModifiers(node)) { + let newModifierFlags: ModifierFlags = ModifierFlags.None; + const enclosingDeclaration = context.enclosingDeclaration && + (isJSDocTypeAlias(context.enclosingDeclaration) ? getSourceFileOfNode(context.enclosingDeclaration) : context.enclosingDeclaration); + if ( + additionalModifierFlags & ModifierFlags.Export && + enclosingDeclaration && (isExportingScope(enclosingDeclaration) || isModuleDeclaration(enclosingDeclaration)) && + canHaveExportModifier(node) + ) { + // Classes, namespaces, variables, functions, interfaces, and types should all be `export`ed in a module context if not private + newModifierFlags |= ModifierFlags.Export; + } + if ( + addingDeclare && !(newModifierFlags & ModifierFlags.Export) && + (!enclosingDeclaration || !(enclosingDeclaration.flags & NodeFlags.Ambient)) && + (isEnumDeclaration(node) || isVariableStatement(node) || isFunctionDeclaration(node) || isClassDeclaration(node) || isModuleDeclaration(node)) + ) { + // Classes, namespaces, variables, enums, and functions all need `declare` modifiers to be valid in a declaration file top-level scope + newModifierFlags |= ModifierFlags.Ambient; + } + if ((additionalModifierFlags & ModifierFlags.Default) && (isClassDeclaration(node) || isInterfaceDeclaration(node) || isFunctionDeclaration(node))) { + newModifierFlags |= ModifierFlags.Default; + } + if (newModifierFlags) { + node = factory.replaceModifiers(node, newModifierFlags | getEffectiveModifierFlags(node)); + } + } + results.push(node); + } + + function serializeTypeAlias(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + const aliasType = getDeclaredTypeOfTypeAlias(symbol); + const typeParams = getSymbolLinks(symbol).typeParameters; + const typeParamDecls = map(typeParams, p => typeParameterToDeclaration(p, context)); + const jsdocAliasDecl = symbol.declarations?.find(isJSDocTypeAlias); + const commentText = getTextOfJSDocComment(jsdocAliasDecl ? jsdocAliasDecl.comment || jsdocAliasDecl.parent.comment : undefined); + const oldFlags = context.flags; + context.flags |= NodeBuilderFlags.InTypeAlias; + const oldEnclosingDecl = context.enclosingDeclaration; + context.enclosingDeclaration = jsdocAliasDecl; + const typeNode = jsdocAliasDecl && jsdocAliasDecl.typeExpression + && isJSDocTypeExpression(jsdocAliasDecl.typeExpression) + && tryReuseExistingNonParameterTypeNode(context, jsdocAliasDecl.typeExpression.type, aliasType, /*host*/ undefined) + || typeToTypeNodeHelper(aliasType, context); + addResult( + setSyntheticLeadingComments( + factory.createTypeAliasDeclaration(/*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, typeNode), + !commentText ? [] : [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }], + ), + modifierFlags, + ); + context.flags = oldFlags; + context.enclosingDeclaration = oldEnclosingDecl; + } + + function serializeInterface(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + const interfaceType = getDeclaredTypeOfClassOrInterface(symbol); + const localParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + const typeParamDecls = map(localParams, p => typeParameterToDeclaration(p, context)); + const baseTypes = getBaseTypes(interfaceType); + const baseType = length(baseTypes) ? getIntersectionType(baseTypes) : undefined; + const members = flatMap(getPropertiesOfType(interfaceType), p => serializePropertySymbolForInterface(p, baseType)); + const callSignatures = serializeSignatures(SignatureKind.Call, interfaceType, baseType, SyntaxKind.CallSignature) as CallSignatureDeclaration[]; + const constructSignatures = serializeSignatures(SignatureKind.Construct, interfaceType, baseType, SyntaxKind.ConstructSignature) as ConstructSignatureDeclaration[]; + const indexSignatures = serializeIndexSignatures(interfaceType, baseType); + + const heritageClauses = !length(baseTypes) ? undefined : [factory.createHeritageClause(SyntaxKind.ExtendsKeyword, mapDefined(baseTypes, b => trySerializeAsTypeReference(b, SymbolFlags.Value)))]; + addResult( + factory.createInterfaceDeclaration( + /*modifiers*/ undefined, + getInternalSymbolName(symbol, symbolName), + typeParamDecls, + heritageClauses, + [...indexSignatures, ...constructSignatures, ...callSignatures, ...members], + ), + modifierFlags, + ); + } + + function getNamespaceMembersForSerialization(symbol: Symbol) { + let exports = arrayFrom(getExportsOfSymbol(symbol).values()); + const merged = getMergedSymbol(symbol); + if (merged !== symbol) { + const membersSet = new Set(exports); + for (const exported of getExportsOfSymbol(merged).values()) { + if (!(getSymbolFlags(resolveSymbol(exported)) & SymbolFlags.Value)) { + membersSet.add(exported); + } + } + exports = arrayFrom(membersSet); + } + return filter(exports, m => isNamespaceMember(m) && isIdentifierText(m.escapedName as string, ScriptTarget.ESNext)); + } + + function isTypeOnlyNamespace(symbol: Symbol) { + return every(getNamespaceMembersForSerialization(symbol), m => !(getSymbolFlags(resolveSymbol(m)) & SymbolFlags.Value)); + } + + function serializeModule(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + const members = getNamespaceMembersForSerialization(symbol); + // Split NS members up by declaration - members whose parent symbol is the ns symbol vs those whose is not (but were added in later via merging) + const locationMap = arrayToMultiMap(members, m => m.parent && m.parent === symbol ? "real" : "merged"); + const realMembers = locationMap.get("real") || emptyArray; + const mergedMembers = locationMap.get("merged") || emptyArray; + // TODO: `suppressNewPrivateContext` is questionable -we need to simply be emitting privates in whatever scope they were declared in, rather + // than whatever scope we traverse to them in. That's a bit of a complex rewrite, since we're not _actually_ tracking privates at all in advance, + // so we don't even have placeholders to fill in. + if (length(realMembers)) { + const localName = getInternalSymbolName(symbol, symbolName); + serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (SymbolFlags.Function | SymbolFlags.Assignment))); + } + if (length(mergedMembers)) { + const containingFile = getSourceFileOfNode(context.enclosingDeclaration); + const localName = getInternalSymbolName(symbol, symbolName); + const nsBody = factory.createModuleBlock([factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(mapDefined(filter(mergedMembers, n => n.escapedName !== InternalSymbolName.ExportEquals), s => { + const name = unescapeLeadingUnderscores(s.escapedName); + const localName = getInternalSymbolName(s, name); + const aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s); + if (containingFile && (aliasDecl ? containingFile !== getSourceFileOfNode(aliasDecl) : !some(s.declarations, d => getSourceFileOfNode(d) === containingFile))) { + context.tracker?.reportNonlocalAugmentation?.(containingFile, symbol, s); + return undefined; + } + const target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true); + includePrivateSymbol(target || s); + const targetName = target ? getInternalSymbolName(target, unescapeLeadingUnderscores(target.escapedName)) : localName; + return factory.createExportSpecifier(/*isTypeOnly*/ false, name === targetName ? undefined : targetName, name); + })), + )]); + addResult( + factory.createModuleDeclaration( + /*modifiers*/ undefined, + factory.createIdentifier(localName), + nsBody, + NodeFlags.Namespace, + ), + ModifierFlags.None, + ); + } + } + + function serializeEnum(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + addResult( + factory.createEnumDeclaration( + factory.createModifiersFromModifierFlags(isConstEnumSymbol(symbol) ? ModifierFlags.Const : 0), + getInternalSymbolName(symbol, symbolName), + map(filter(getPropertiesOfType(getTypeOfSymbol(symbol)), p => !!(p.flags & SymbolFlags.EnumMember)), p => { + // TODO: Handle computed names + // I hate that to get the initialized value we need to walk back to the declarations here; but there's no + // other way to get the possible const value of an enum member that I'm aware of, as the value is cached + // _on the declaration_, not on the declaration's symbol... + const initializedValue = p.declarations && p.declarations[0] && isEnumMember(p.declarations[0]) ? getConstantValue(p.declarations[0]) : undefined; + return factory.createEnumMember( + unescapeLeadingUnderscores(p.escapedName), + initializedValue === undefined ? undefined : + typeof initializedValue === "string" ? factory.createStringLiteral(initializedValue) : + factory.createNumericLiteral(initializedValue), + ); + }), + ), + modifierFlags, + ); + } + + function serializeAsFunctionNamespaceMerge(type: Type, symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { + const signatures = getSignaturesOfType(type, SignatureKind.Call); + for (const sig of signatures) { + // Each overload becomes a separate function declaration, in order + const decl = signatureToSignatureDeclarationHelper(sig, SyntaxKind.FunctionDeclaration, context, { name: factory.createIdentifier(localName) }) as FunctionDeclaration; + addResult(setTextRange(context, decl, getSignatureTextRangeLocation(sig)), modifierFlags); + } + // Module symbol emit will take care of module-y members, provided it has exports + if (!(symbol.flags & (SymbolFlags.ValueModule | SymbolFlags.NamespaceModule) && !!symbol.exports && !!symbol.exports.size)) { + const props = filter(getPropertiesOfType(type), isNamespaceMember); + serializeAsNamespaceDeclaration(props, localName, modifierFlags, /*suppressNewPrivateContext*/ true); + } + } + + function getSignatureTextRangeLocation(signature: Signature) { + if (signature.declaration && signature.declaration.parent) { + if (isBinaryExpression(signature.declaration.parent) && getAssignmentDeclarationKind(signature.declaration.parent) === AssignmentDeclarationKind.Property) { + return signature.declaration.parent; + } + // for expressions assigned to `var`s, use the `var` as the text range + if (isVariableDeclaration(signature.declaration.parent) && signature.declaration.parent.parent) { + return signature.declaration.parent.parent; + } + } + return signature.declaration; + } + + function serializeAsNamespaceDeclaration(props: readonly Symbol[], localName: string, modifierFlags: ModifierFlags, suppressNewPrivateContext: boolean) { + if (length(props)) { + const localVsRemoteMap = arrayToMultiMap(props, p => !length(p.declarations) || some(p.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(context.enclosingDeclaration!)) ? "local" : "remote"); + const localProps = localVsRemoteMap.get("local") || emptyArray; + // handle remote props first - we need to make an `import` declaration that points at the module containing each remote + // prop in the outermost scope (TODO: a namespace within a namespace would need to be appropriately handled by this) + // Example: + // import Foo_1 = require("./exporter"); + // export namespace ns { + // import Foo = Foo_1.Foo; + // export { Foo }; + // export const c: number; + // } + // This is needed because in JS, statements like `const x = require("./f")` support both type and value lookup, even if they're + // normally just value lookup (so it functions kinda like an alias even when it's not an alias) + // _Usually_, we'll simply print the top-level as an alias instead of a `var` in such situations, however is is theoretically + // possible to encounter a situation where a type has members from both the current file and other files - in those situations, + // emit akin to the above would be needed. + + // Add a namespace + // Create namespace as non-synthetic so it is usable as an enclosing declaration + let fakespace = parseNodeFactory.createModuleDeclaration(/*modifiers*/ undefined, factory.createIdentifier(localName), factory.createModuleBlock([]), NodeFlags.Namespace); + setParent(fakespace, enclosingDeclaration as SourceFile | NamespaceDeclaration); + fakespace.locals = createSymbolTable(props); + fakespace.symbol = props[0].parent!; + + const oldResults = results; + results = []; + const oldAddingDeclare = addingDeclare; + addingDeclare = false; + const subcontext = { ...context, enclosingDeclaration: fakespace }; + const oldContext = context; + context = subcontext; + // TODO: implement handling for the localVsRemoteMap.get("remote") - should be difficult to trigger (see comment above), as only interesting cross-file js merges should make this possible + visitSymbolTable(createSymbolTable(localProps), suppressNewPrivateContext, /*propertyAsAlias*/ true); + context = oldContext; + addingDeclare = oldAddingDeclare; + const declarations = results; + results = oldResults; + // replace namespace with synthetic version + const defaultReplaced = map(declarations, d => + isExportAssignment(d) && !d.isExportEquals && isIdentifier(d.expression) ? factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, d.expression, factory.createIdentifier(InternalSymbolName.Default))]), + ) : d); + const exportModifierStripped = every(defaultReplaced, d => hasSyntacticModifier(d, ModifierFlags.Export)) ? map(defaultReplaced as Extract[], removeExportModifier) : defaultReplaced; + fakespace = factory.updateModuleDeclaration( + fakespace, + fakespace.modifiers, + fakespace.name, + factory.createModuleBlock(exportModifierStripped), + ); + addResult(fakespace, modifierFlags); // namespaces can never be default exported + } + } + + function isNamespaceMember(p: Symbol) { + return !!(p.flags & (SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias)) || + !(p.flags & SymbolFlags.Prototype || p.escapedName === "prototype" || p.valueDeclaration && isStatic(p.valueDeclaration) && isClassLike(p.valueDeclaration.parent)); + } + + function sanitizeJSDocImplements(clauses: readonly ExpressionWithTypeArguments[]): ExpressionWithTypeArguments[] | undefined { + const result = mapDefined(clauses, e => { + const oldEnclosing = context.enclosingDeclaration; + context.enclosingDeclaration = e; + let expr = e.expression; + if (isEntityNameExpression(expr)) { + if (isIdentifier(expr) && idText(expr) === "") { + return cleanup(/*result*/ undefined); // Empty heritage clause, should be an error, but prefer emitting no heritage clauses to reemitting the empty one + } + let introducesError: boolean; + ({ introducesError, node: expr } = trackExistingEntityName(expr, context)); + if (introducesError) { + return cleanup(/*result*/ undefined); + } + } + return cleanup(factory.createExpressionWithTypeArguments( + expr, + map(e.typeArguments, a => + tryReuseExistingNonParameterTypeNode(context, a, getTypeFromTypeNode(context, a)) + || typeToTypeNodeHelper(getTypeFromTypeNode(context, a), context)), + )); + + function cleanup(result: T): T { + context.enclosingDeclaration = oldEnclosing; + return result; + } + }); + if (result.length === clauses.length) { + return result; + } + return undefined; + } + + function serializeAsClass(symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { + const originalDecl = symbol.declarations?.find(isClassLike); + const oldEnclosing = context.enclosingDeclaration; + context.enclosingDeclaration = originalDecl || oldEnclosing; + const localParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + const typeParamDecls = map(localParams, p => typeParameterToDeclaration(p, context)); + const classType = getTypeWithThisArgument(getDeclaredTypeOfClassOrInterface(symbol)) as InterfaceType; + const baseTypes = getBaseTypes(classType); + const originalImplements = originalDecl && getEffectiveImplementsTypeNodes(originalDecl); + const implementsExpressions = originalImplements && sanitizeJSDocImplements(originalImplements) + || mapDefined(getImplementsTypes(classType), serializeImplementedType); + const staticType = getTypeOfSymbol(symbol); + const isClass = !!staticType.symbol?.valueDeclaration && isClassLike(staticType.symbol.valueDeclaration); + const staticBaseType = isClass + ? getBaseConstructorTypeOfClass(staticType as InterfaceType) + : anyType; + const heritageClauses = [ + ...!length(baseTypes) ? [] : [factory.createHeritageClause(SyntaxKind.ExtendsKeyword, map(baseTypes, b => serializeBaseType(b, staticBaseType, localName)))], + ...!length(implementsExpressions) ? [] : [factory.createHeritageClause(SyntaxKind.ImplementsKeyword, implementsExpressions)], + ]; + const symbolProps = getNonInheritedProperties(classType, baseTypes, getPropertiesOfType(classType)); + const publicSymbolProps = filter(symbolProps, s => { + // `valueDeclaration` could be undefined if inherited from + // a union/intersection base type, but inherited properties + // don't matter here. + const valueDecl = s.valueDeclaration; + return !!valueDecl && !(isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name)); + }); + const hasPrivateIdentifier = some(symbolProps, s => { + // `valueDeclaration` could be undefined if inherited from + // a union/intersection base type, but inherited properties + // don't matter here. + const valueDecl = s.valueDeclaration; + return !!valueDecl && isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name); + }); + // Boil down all private properties into a single one. + const privateProperties = hasPrivateIdentifier ? + [factory.createPropertyDeclaration( + /*modifiers*/ undefined, + factory.createPrivateIdentifier("#private"), + /*questionOrExclamationToken*/ undefined, + /*type*/ undefined, + /*initializer*/ undefined, + )] : + emptyArray; + const publicProperties = flatMap(publicSymbolProps, p => serializePropertySymbolForClass(p, /*isStatic*/ false, baseTypes[0])); + // Consider static members empty if symbol also has function or module meaning - function namespacey emit will handle statics + const staticMembers = flatMap( + filter(getPropertiesOfType(staticType), p => !(p.flags & SymbolFlags.Prototype) && p.escapedName !== "prototype" && !isNamespaceMember(p)), + p => serializePropertySymbolForClass(p, /*isStatic*/ true, staticBaseType), + ); + // When we encounter an `X.prototype.y` assignment in a JS file, we bind `X` as a class regardless as to whether + // the value is ever initialized with a class or function-like value. For cases where `X` could never be + // created via `new`, we will inject a `private constructor()` declaration to indicate it is not createable. + const isNonConstructableClassLikeInJsFile = !isClass && + !!symbol.valueDeclaration && + isInJSFile(symbol.valueDeclaration) && + !some(getSignaturesOfType(staticType, SignatureKind.Construct)); + const constructors = isNonConstructableClassLikeInJsFile ? + [factory.createConstructorDeclaration(factory.createModifiersFromModifierFlags(ModifierFlags.Private), [], /*body*/ undefined)] : + serializeSignatures(SignatureKind.Construct, staticType, staticBaseType, SyntaxKind.Constructor) as ConstructorDeclaration[]; + const indexSignatures = serializeIndexSignatures(classType, baseTypes[0]); + context.enclosingDeclaration = oldEnclosing; + addResult( + setTextRange( + context, + factory.createClassDeclaration( + /*modifiers*/ undefined, + localName, + typeParamDecls, + heritageClauses, + [...indexSignatures, ...staticMembers, ...constructors, ...publicProperties, ...privateProperties], + ), + symbol.declarations && filter(symbol.declarations, d => isClassDeclaration(d) || isClassExpression(d))[0], + ), + modifierFlags, + ); + } + + function getSomeTargetNameFromDeclarations(declarations: Declaration[] | undefined) { + return firstDefined(declarations, d => { + if (isImportSpecifier(d) || isExportSpecifier(d)) { + return moduleExportNameTextUnescaped(d.propertyName || d.name); + } + if (isBinaryExpression(d) || isExportAssignment(d)) { + const expression = isExportAssignment(d) ? d.expression : d.right; + if (isPropertyAccessExpression(expression)) { + return idText(expression.name); + } + } + if (isAliasSymbolDeclaration(d)) { + // This is... heuristic, at best. But it's probably better than always printing the name of the shorthand ambient module. + const name = getNameOfDeclaration(d); + if (name && isIdentifier(name)) { + return idText(name); + } + } + return undefined; + }); + } + + function serializeAsAlias(symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { + // synthesize an alias, eg `export { symbolName as Name }` + // need to mark the alias `symbol` points at + // as something we need to serialize as a private declaration as well + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + const target = getMergedSymbol(getTargetOfAliasDeclaration(node, /*dontRecursivelyResolve*/ true)); + if (!target) { + return; + } + // If `target` refers to a shorthand module symbol, the name we're trying to pull out isn;t recoverable from the target symbol + // In such a scenario, we must fall back to looking for an alias declaration on `symbol` and pulling the target name from that + let verbatimTargetName = isShorthandAmbientModuleSymbol(target) && getSomeTargetNameFromDeclarations(symbol.declarations) || unescapeLeadingUnderscores(target.escapedName); + if (verbatimTargetName === InternalSymbolName.ExportEquals && allowSyntheticDefaultImports) { + // target refers to an `export=` symbol that was hoisted into a synthetic default - rename here to match + verbatimTargetName = InternalSymbolName.Default; + } + const targetName = getInternalSymbolName(target, verbatimTargetName); + includePrivateSymbol(target); // the target may be within the same scope - attempt to serialize it first + switch (node.kind) { + case SyntaxKind.BindingElement: + if (node.parent?.parent?.kind === SyntaxKind.VariableDeclaration) { + // const { SomeClass } = require('./lib'); + const specifier = getSpecifierForModuleSymbol(target.parent || target, context); // './lib' + const { propertyName } = node as BindingElement; + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause( + /*isTypeOnly*/ false, + /*name*/ undefined, + factory.createNamedImports([factory.createImportSpecifier( + /*isTypeOnly*/ false, + propertyName && isIdentifier(propertyName) ? factory.createIdentifier(idText(propertyName)) : undefined, + factory.createIdentifier(localName), + )]), + ), + factory.createStringLiteral(specifier), + /*attributes*/ undefined, + ), + ModifierFlags.None, + ); + break; + } + // We don't know how to serialize this (nested?) binding element + Debug.failBadSyntaxKind(node.parent?.parent || node, "Unhandled binding element grandparent kind in declaration serialization"); + break; + case SyntaxKind.ShorthandPropertyAssignment: + if (node.parent?.parent?.kind === SyntaxKind.BinaryExpression) { + // module.exports = { SomeClass } + serializeExportSpecifier( + unescapeLeadingUnderscores(symbol.escapedName), + targetName, + ); + } + break; + case SyntaxKind.VariableDeclaration: + // commonjs require: const x = require('y') + if (isPropertyAccessExpression((node as VariableDeclaration).initializer!)) { + // const x = require('y').z + const initializer = (node as VariableDeclaration).initializer! as PropertyAccessExpression; // require('y').z + const uniqueName = factory.createUniqueName(localName); // _x + const specifier = getSpecifierForModuleSymbol(target.parent || target, context); // 'y' + // import _x = require('y'); + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + uniqueName, + factory.createExternalModuleReference(factory.createStringLiteral(specifier)), + ), + ModifierFlags.None, + ); + // import x = _x.z + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createIdentifier(localName), + factory.createQualifiedName(uniqueName, initializer.name as Identifier), + ), + modifierFlags, + ); + break; + } + // else fall through and treat commonjs require just like import= + case SyntaxKind.ImportEqualsDeclaration: + // This _specifically_ only exists to handle json declarations - where we make aliases, but since + // we emit no declarations for the json document, must not refer to it in the declarations + if (target.escapedName === InternalSymbolName.ExportEquals && some(target.declarations, d => isSourceFile(d) && isJsonSourceFile(d))) { + serializeMaybeAliasAssignment(symbol); + break; + } + // Could be a local `import localName = ns.member` or + // an external `import localName = require("whatever")` + const isLocalImport = !(target.flags & SymbolFlags.ValueModule) && !isVariableDeclaration(node); + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createIdentifier(localName), + isLocalImport + ? symbolToName(target, context, SymbolFlags.All, /*expectsIdentifier*/ false) + : factory.createExternalModuleReference(factory.createStringLiteral(getSpecifierForModuleSymbol(target, context))), + ), + isLocalImport ? modifierFlags : ModifierFlags.None, + ); + break; + case SyntaxKind.NamespaceExportDeclaration: + // export as namespace foo + // TODO: Not part of a file's local or export symbol tables + // Is bound into file.symbol.globalExports instead, which we don't currently traverse + addResult(factory.createNamespaceExportDeclaration(idText((node as NamespaceExportDeclaration).name)), ModifierFlags.None); + break; + case SyntaxKind.ImportClause: { + const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects + const specifier = context.bundled ? factory.createStringLiteral(generatedSpecifier) : (node as ImportClause).parent.moduleSpecifier; + const attributes = isImportDeclaration(node.parent) ? node.parent.attributes : undefined; + const isTypeOnly = isJSDocImportTag((node as ImportClause).parent); + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause(isTypeOnly, factory.createIdentifier(localName), /*namedBindings*/ undefined), + specifier, + attributes, + ), + ModifierFlags.None, + ); + break; + } + case SyntaxKind.NamespaceImport: { + const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects + const specifier = context.bundled ? factory.createStringLiteral(generatedSpecifier) : (node as NamespaceImport).parent.parent.moduleSpecifier; + const isTypeOnly = isJSDocImportTag((node as NamespaceImport).parent.parent); + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause(isTypeOnly, /*name*/ undefined, factory.createNamespaceImport(factory.createIdentifier(localName))), + specifier, + (node as ImportClause).parent.attributes, + ), + ModifierFlags.None, + ); + break; + } + case SyntaxKind.NamespaceExport: + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamespaceExport(factory.createIdentifier(localName)), + factory.createStringLiteral(getSpecifierForModuleSymbol(target, context)), + ), + ModifierFlags.None, + ); + break; + case SyntaxKind.ImportSpecifier: { + const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects + const specifier = context.bundled ? factory.createStringLiteral(generatedSpecifier) : (node as ImportSpecifier).parent.parent.parent.moduleSpecifier; + const isTypeOnly = isJSDocImportTag((node as ImportSpecifier).parent.parent.parent); + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause( + isTypeOnly, + /*name*/ undefined, + factory.createNamedImports([ + factory.createImportSpecifier( + /*isTypeOnly*/ false, + localName !== verbatimTargetName ? factory.createIdentifier(verbatimTargetName) : undefined, + factory.createIdentifier(localName), + ), + ]), + ), + specifier, + (node as ImportSpecifier).parent.parent.parent.attributes, + ), + ModifierFlags.None, + ); + break; + } + case SyntaxKind.ExportSpecifier: + // does not use localName because the symbol name in this case refers to the name in the exports table, + // which we must exactly preserve + const specifier = (node.parent.parent as ExportDeclaration).moduleSpecifier; + if (specifier) { + const propertyName = (node as ExportSpecifier).propertyName; + if (propertyName && moduleExportNameIsDefault(propertyName)) { + verbatimTargetName = InternalSymbolName.Default; + } + } + // targetName is only used when the target is local, as otherwise the target is an alias that points at + // another file + serializeExportSpecifier( + unescapeLeadingUnderscores(symbol.escapedName), + specifier ? verbatimTargetName : targetName, + specifier && isStringLiteralLike(specifier) ? factory.createStringLiteral(specifier.text) : undefined, + ); + break; + case SyntaxKind.ExportAssignment: + serializeMaybeAliasAssignment(symbol); + break; + case SyntaxKind.BinaryExpression: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + // Could be best encoded as though an export specifier or as though an export assignment + // If name is default or export=, do an export assignment + // Otherwise do an export specifier + if (symbol.escapedName === InternalSymbolName.Default || symbol.escapedName === InternalSymbolName.ExportEquals) { + serializeMaybeAliasAssignment(symbol); + } + else { + serializeExportSpecifier(localName, targetName); + } + break; + default: + return Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!"); + } + } + + function serializeExportSpecifier(localName: string, targetName: string, specifier?: Expression) { + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, localName !== targetName ? targetName : undefined, localName)]), + specifier, + ), + ModifierFlags.None, + ); + } + + /** + * Returns `true` if an export assignment or declaration was produced for the symbol + */ + function serializeMaybeAliasAssignment(symbol: Symbol): boolean { + if (symbol.flags & SymbolFlags.Prototype) { + return false; + } + const name = unescapeLeadingUnderscores(symbol.escapedName); + const isExportEquals = name === InternalSymbolName.ExportEquals; + const isDefault = name === InternalSymbolName.Default; + const isExportAssignmentCompatibleSymbolName = isExportEquals || isDefault; + // synthesize export = ref + // ref should refer to either be a locally scoped symbol which we need to emit, or + // a reference to another namespace/module which we may need to emit an `import` statement for + const aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol); + // serialize what the alias points to, preserve the declaration's initializer + const target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true); + // If the target resolves and resolves to a thing defined in this file, emit as an alias, otherwise emit as a const + if (target && length(target.declarations) && some(target.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(enclosingDeclaration))) { + // In case `target` refers to a namespace member, look at the declaration and serialize the leftmost symbol in it + // eg, `namespace A { export class B {} }; exports = A.B;` + // Technically, this is all that's required in the case where the assignment is an entity name expression + const expr = aliasDecl && ((isExportAssignment(aliasDecl) || isBinaryExpression(aliasDecl)) ? getExportAssignmentExpression(aliasDecl) : getPropertyAssignmentAliasLikeExpression(aliasDecl as ShorthandPropertyAssignment | PropertyAssignment | PropertyAccessExpression)); + const first = expr && isEntityNameExpression(expr) ? getFirstNonModuleExportsIdentifier(expr) : undefined; + const referenced = first && resolveEntityName(first, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, enclosingDeclaration); + if (referenced || target) { + includePrivateSymbol(referenced || target); + } + + // We disable the context's symbol tracker for the duration of this name serialization + // as, by virtue of being here, the name is required to print something, and we don't want to + // issue a visibility error on it. Only anonymous classes that an alias points at _would_ issue + // a visibility error here (as they're not visible within any scope), but we want to hoist them + // into the containing scope anyway, so we want to skip the visibility checks. + const prevDisableTrackSymbol = context.tracker.disableTrackSymbol; + context.tracker.disableTrackSymbol = true; + if (isExportAssignmentCompatibleSymbolName) { + results.push(factory.createExportAssignment( + /*modifiers*/ undefined, + isExportEquals, + symbolToExpression(target, context, SymbolFlags.All), + )); + } + else { + if (first === expr && first) { + // serialize as `export {target as name}` + serializeExportSpecifier(name, idText(first)); + } + else if (expr && isClassExpression(expr)) { + serializeExportSpecifier(name, getInternalSymbolName(target, symbolName(target))); + } + else { + // serialize as `import _Ref = t.arg.et; export { _Ref as name }` + const varName = getUnusedName(name, symbol); + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createIdentifier(varName), + symbolToName(target, context, SymbolFlags.All, /*expectsIdentifier*/ false), + ), + ModifierFlags.None, + ); + serializeExportSpecifier(name, varName); + } + } + context.tracker.disableTrackSymbol = prevDisableTrackSymbol; + return true; + } + else { + // serialize as an anonymous property declaration + const varName = getUnusedName(name, symbol); + // We have to use `getWidenedType` here since the object within a json file is unwidened within the file + // (Unwidened types can only exist in expression contexts and should never be serialized) + const typeToSerialize = getWidenedType(getTypeOfSymbol(getMergedSymbol(symbol))); + if (isTypeRepresentableAsFunctionNamespaceMerge(typeToSerialize, symbol)) { + // If there are no index signatures and `typeToSerialize` is an object type, emit as a namespace instead of a const + serializeAsFunctionNamespaceMerge(typeToSerialize, symbol, varName, isExportAssignmentCompatibleSymbolName ? ModifierFlags.None : ModifierFlags.Export); + } + else { + const flags = context.enclosingDeclaration?.kind === SyntaxKind.ModuleDeclaration && (!(symbol.flags & SymbolFlags.Accessor) || symbol.flags & SymbolFlags.SetAccessor) ? NodeFlags.Let : NodeFlags.Const; + const statement = factory.createVariableStatement( + /*modifiers*/ undefined, + factory.createVariableDeclarationList([ + factory.createVariableDeclaration(varName, /*exclamationToken*/ undefined, serializeTypeForDeclaration(context, /*declaration*/ undefined, typeToSerialize, symbol)), + ], flags), + ); + // Inlined JSON types exported with [module.]exports= will already emit an export=, so should use `declare`. + // Otherwise, the type itself should be exported. + addResult( + statement, + target && target.flags & SymbolFlags.Property && target.escapedName === InternalSymbolName.ExportEquals ? ModifierFlags.Ambient + : name === varName ? ModifierFlags.Export + : ModifierFlags.None, + ); + } + if (isExportAssignmentCompatibleSymbolName) { + results.push(factory.createExportAssignment( + /*modifiers*/ undefined, + isExportEquals, + factory.createIdentifier(varName), + )); + return true; + } + else if (name !== varName) { + serializeExportSpecifier(name, varName); + return true; + } + return false; + } + } + + function isTypeRepresentableAsFunctionNamespaceMerge(typeToSerialize: Type, hostSymbol: Symbol) { + // Only object types which are not constructable, or indexable, whose members all come from the + // context source file, and whose property names are all valid identifiers and not late-bound, _and_ + // whose input is not type annotated (if the input symbol has an annotation we can reuse, we should prefer it) + const ctxSrc = getSourceFileOfNode(context.enclosingDeclaration); + return getObjectFlags(typeToSerialize) & (ObjectFlags.Anonymous | ObjectFlags.Mapped) && + !some(typeToSerialize.symbol?.declarations, isTypeNode) && // If the type comes straight from a type node, we shouldn't try to break it up + !length(getIndexInfosOfType(typeToSerialize)) && + !isClassInstanceSide(typeToSerialize) && // While a class instance is potentially representable as a NS, prefer printing a reference to the instance type and serializing the class + !!(length(filter(getPropertiesOfType(typeToSerialize), isNamespaceMember)) || length(getSignaturesOfType(typeToSerialize, SignatureKind.Call))) && + !length(getSignaturesOfType(typeToSerialize, SignatureKind.Construct)) && // TODO: could probably serialize as function + ns + class, now that that's OK + !getDeclarationWithTypeAnnotation(hostSymbol, enclosingDeclaration) && + !(typeToSerialize.symbol && some(typeToSerialize.symbol.declarations, d => getSourceFileOfNode(d) !== ctxSrc)) && + !some(getPropertiesOfType(typeToSerialize), p => isLateBoundName(p.escapedName)) && + !some(getPropertiesOfType(typeToSerialize), p => some(p.declarations, d => getSourceFileOfNode(d) !== ctxSrc)) && + every(getPropertiesOfType(typeToSerialize), p => { + if (!isIdentifierText(symbolName(p), languageVersion)) { + return false; + } + if (!(p.flags & SymbolFlags.Accessor)) { + return true; + } + return getNonMissingTypeOfSymbol(p) === getWriteTypeOfSymbol(p); + }); + } + + function makeSerializePropertySymbol( + createProperty: ( + modifiers: readonly Modifier[] | undefined, + name: string | PropertyName, + questionOrExclamationToken: QuestionToken | undefined, + type: TypeNode | undefined, + initializer: Expression | undefined, + ) => T, + methodKind: SignatureDeclaration["kind"], + useAccessors: true, + ): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => T | AccessorDeclaration | (T | AccessorDeclaration)[]; + function makeSerializePropertySymbol( + createProperty: ( + modifiers: readonly Modifier[] | undefined, + name: string | PropertyName, + questionOrExclamationToken: QuestionToken | undefined, + type: TypeNode | undefined, + initializer: Expression | undefined, + ) => T, + methodKind: SignatureDeclaration["kind"], + useAccessors: false, + ): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => T | T[]; + function makeSerializePropertySymbol( + createProperty: ( + modifiers: readonly Modifier[] | undefined, + name: string | PropertyName, + questionOrExclamationToken: QuestionToken | undefined, + type: TypeNode | undefined, + initializer: Expression | undefined, + ) => T, + methodKind: SignatureDeclaration["kind"], + useAccessors: boolean, + ): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => T | AccessorDeclaration | (T | AccessorDeclaration)[] { + return function serializePropertySymbol(p: Symbol, isStatic: boolean, baseType: Type | undefined): T | AccessorDeclaration | (T | AccessorDeclaration)[] { + const modifierFlags = getDeclarationModifierFlagsFromSymbol(p); + const isPrivate = !!(modifierFlags & ModifierFlags.Private); + if (isStatic && (p.flags & (SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias))) { + // Only value-only-meaning symbols can be correctly encoded as class statics, type/namespace/alias meaning symbols + // need to be merged namespace members + return []; + } + if ( + p.flags & SymbolFlags.Prototype || p.escapedName === "constructor" || + (baseType && getPropertyOfType(baseType, p.escapedName) + && isReadonlySymbol(getPropertyOfType(baseType, p.escapedName)!) === isReadonlySymbol(p) + && (p.flags & SymbolFlags.Optional) === (getPropertyOfType(baseType, p.escapedName)!.flags & SymbolFlags.Optional) + && isTypeIdenticalTo(getTypeOfSymbol(p), getTypeOfPropertyOfType(baseType, p.escapedName)!)) + ) { + return []; + } + const flag = (modifierFlags & ~ModifierFlags.Async) | (isStatic ? ModifierFlags.Static : 0); + const name = getPropertyNameNodeForSymbol(p, context); + const firstPropertyLikeDecl = p.declarations?.find(or(isPropertyDeclaration, isAccessor, isVariableDeclaration, isPropertySignature, isBinaryExpression, isPropertyAccessExpression)); + if (p.flags & SymbolFlags.Accessor && useAccessors) { + const result: AccessorDeclaration[] = []; + if (p.flags & SymbolFlags.SetAccessor) { + const setter = p.declarations && forEach(p.declarations, d => { + if (d.kind === SyntaxKind.SetAccessor) { + return d as SetAccessorDeclaration; + } + if (isCallExpression(d) && isBindableObjectDefinePropertyCall(d)) { + return forEach(d.arguments[2].properties, propDecl => { + const id = getNameOfDeclaration(propDecl); + if (!!id && isIdentifier(id) && idText(id) === "set") { + return propDecl; + } + }); + } + }); + + Debug.assert(!!setter); + const paramSymbol = isFunctionLikeDeclaration(setter) ? getSignatureFromDeclaration(setter).parameters[0] : undefined; + + result.push(setTextRange( + context, + factory.createSetAccessorDeclaration( + factory.createModifiersFromModifierFlags(flag), + name, + [factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + paramSymbol ? parameterToParameterDeclarationName(paramSymbol, getEffectiveParameterDeclaration(paramSymbol), context) : "value", + /*questionToken*/ undefined, + isPrivate ? undefined : serializeTypeForDeclaration(context, /*declaration*/ undefined, getWriteTypeOfSymbol(p), p), + )], + /*body*/ undefined, + ), + p.declarations?.find(isSetAccessor) || firstPropertyLikeDecl, + )); + } + if (p.flags & SymbolFlags.GetAccessor) { + const isPrivate = modifierFlags & ModifierFlags.Private; + result.push(setTextRange( + context, + factory.createGetAccessorDeclaration( + factory.createModifiersFromModifierFlags(flag), + name, + [], + isPrivate ? undefined : serializeTypeForDeclaration(context, /*declaration*/ undefined, getTypeOfSymbol(p), p), + /*body*/ undefined, + ), + p.declarations?.find(isGetAccessor) || firstPropertyLikeDecl, + )); + } + return result; + } + // This is an else/if as accessors and properties can't merge in TS, but might in JS + // If this happens, we assume the accessor takes priority, as it imposes more constraints + else if (p.flags & (SymbolFlags.Property | SymbolFlags.Variable | SymbolFlags.Accessor)) { + return setTextRange( + context, + createProperty( + factory.createModifiersFromModifierFlags((isReadonlySymbol(p) ? ModifierFlags.Readonly : 0) | flag), + name, + p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + isPrivate ? undefined : serializeTypeForDeclaration(context, /*declaration*/ undefined, getWriteTypeOfSymbol(p), p), + // TODO: https://github.com/microsoft/TypeScript/pull/32372#discussion_r328386357 + // interface members can't have initializers, however class members _can_ + /*initializer*/ undefined, + ), + p.declarations?.find(or(isPropertyDeclaration, isVariableDeclaration)) || firstPropertyLikeDecl, + ); + } + if (p.flags & (SymbolFlags.Method | SymbolFlags.Function)) { + const type = getTypeOfSymbol(p); + const signatures = getSignaturesOfType(type, SignatureKind.Call); + if (flag & ModifierFlags.Private) { + return setTextRange( + context, + createProperty( + factory.createModifiersFromModifierFlags((isReadonlySymbol(p) ? ModifierFlags.Readonly : 0) | flag), + name, + p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + /*type*/ undefined, + /*initializer*/ undefined, + ), + p.declarations?.find(isFunctionLikeDeclaration) || signatures[0] && signatures[0].declaration || p.declarations && p.declarations[0], + ); + } + + const results = []; + for (const sig of signatures) { + // Each overload becomes a separate method declaration, in order + const decl = signatureToSignatureDeclarationHelper( + sig, + methodKind, + context, + { + name, + questionToken: p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + modifiers: flag ? factory.createModifiersFromModifierFlags(flag) : undefined, + }, + ); + const location = sig.declaration && isPrototypePropertyAssignment(sig.declaration.parent) ? sig.declaration.parent : sig.declaration; + results.push(setTextRange(context, decl, location)); + } + return results as unknown as T[]; + } + // The `Constructor`'s symbol isn't in the class's properties lists, obviously, since it's a signature on the static + return Debug.fail(`Unhandled class member kind! ${(p as any).__debugFlags || p.flags}`); + }; + } + + function serializePropertySymbolForInterface(p: Symbol, baseType: Type | undefined) { + return serializePropertySymbolForInterfaceWorker(p, /*isStatic*/ false, baseType); + } + + function serializeSignatures(kind: SignatureKind, input: Type, baseType: Type | undefined, outputKind: SignatureDeclaration["kind"]) { + const signatures = getSignaturesOfType(input, kind); + if (kind === SignatureKind.Construct) { + if (!baseType && every(signatures, s => length(s.parameters) === 0)) { + return []; // No base type, every constructor is empty - elide the extraneous `constructor()` + } + if (baseType) { + // If there is a base type, if every signature in the class is identical to a signature in the baseType, elide all the declarations + const baseSigs = getSignaturesOfType(baseType, SignatureKind.Construct); + if (!length(baseSigs) && every(signatures, s => length(s.parameters) === 0)) { + return []; // Base had no explicit signatures, if all our signatures are also implicit, return an empty list + } + if (baseSigs.length === signatures.length) { + let failed = false; + for (let i = 0; i < baseSigs.length; i++) { + if (!compareSignaturesIdentical(signatures[i], baseSigs[i], /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true, compareTypesIdentical)) { + failed = true; + break; + } + } + if (!failed) { + return []; // Every signature was identical - elide constructor list as it is inherited + } + } + } + let privateProtected: ModifierFlags = 0; + for (const s of signatures) { + if (s.declaration) { + privateProtected |= getSelectedEffectiveModifierFlags(s.declaration, ModifierFlags.Private | ModifierFlags.Protected); + } + } + if (privateProtected) { + return [setTextRange( + context, + factory.createConstructorDeclaration( + factory.createModifiersFromModifierFlags(privateProtected), + /*parameters*/ [], + /*body*/ undefined, + ), + signatures[0].declaration, + )]; + } + } + + const results = []; + for (const sig of signatures) { + // Each overload becomes a separate constructor declaration, in order + const decl = signatureToSignatureDeclarationHelper(sig, outputKind, context); + results.push(setTextRange(context, decl, sig.declaration)); + } + return results; + } + + function serializeIndexSignatures(input: Type, baseType: Type | undefined) { + const results: IndexSignatureDeclaration[] = []; + for (const info of getIndexInfosOfType(input)) { + if (baseType) { + const baseInfo = getIndexInfoOfType(baseType, info.keyType); + if (baseInfo) { + if (isTypeIdenticalTo(info.type, baseInfo.type)) { + continue; // elide identical index signatures + } + } + } + results.push(indexInfoToIndexSignatureDeclarationHelper(info, context, /*typeNode*/ undefined)); + } + return results; + } + + function serializeBaseType(t: Type, staticType: Type, rootName: string) { + const ref = trySerializeAsTypeReference(t, SymbolFlags.Value); + if (ref) { + return ref; + } + const tempName = getUnusedName(`${rootName}_base`); + const statement = factory.createVariableStatement( + /*modifiers*/ undefined, + factory.createVariableDeclarationList([ + factory.createVariableDeclaration(tempName, /*exclamationToken*/ undefined, typeToTypeNodeHelper(staticType, context)), + ], NodeFlags.Const), + ); + addResult(statement, ModifierFlags.None); + return factory.createExpressionWithTypeArguments(factory.createIdentifier(tempName), /*typeArguments*/ undefined); + } + + function trySerializeAsTypeReference(t: Type, flags: SymbolFlags) { + let typeArgs: TypeNode[] | undefined; + let reference: Expression | undefined; + + // We don't use `isValueSymbolAccessible` below. since that considers alternative containers (like modules) + // which we can't write out in a syntactically valid way as an expression + if ((t as TypeReference).target && isSymbolAccessibleByFlags((t as TypeReference).target.symbol, enclosingDeclaration, flags)) { + typeArgs = map(getTypeArguments(t as TypeReference), t => typeToTypeNodeHelper(t, context)); + reference = symbolToExpression((t as TypeReference).target.symbol, context, SymbolFlags.Type); + } + else if (t.symbol && isSymbolAccessibleByFlags(t.symbol, enclosingDeclaration, flags)) { + reference = symbolToExpression(t.symbol, context, SymbolFlags.Type); + } + if (reference) { + return factory.createExpressionWithTypeArguments(reference, typeArgs); + } + } + + function serializeImplementedType(t: Type) { + const ref = trySerializeAsTypeReference(t, SymbolFlags.Type); + if (ref) { + return ref; + } + if (t.symbol) { + return factory.createExpressionWithTypeArguments(symbolToExpression(t.symbol, context, SymbolFlags.Type), /*typeArguments*/ undefined); + } + } + + function getUnusedName(input: string, symbol?: Symbol): string { + const id = symbol ? getSymbolId(symbol) : undefined; + if (id) { + if (context.remappedSymbolNames!.has(id)) { + return context.remappedSymbolNames!.get(id)!; + } + } + if (symbol) { + input = getNameCandidateWorker(symbol, input); + } + let i = 0; + const original = input; + while (context.usedSymbolNames?.has(input)) { + i++; + input = `${original}_${i}`; + } + context.usedSymbolNames?.add(input); + if (id) { + context.remappedSymbolNames!.set(id, input); + } + return input; + } + + function getNameCandidateWorker(symbol: Symbol, localName: string) { + if (localName === InternalSymbolName.Default || localName === InternalSymbolName.Class || localName === InternalSymbolName.Function) { + const flags = context.flags; + context.flags |= NodeBuilderFlags.InInitialEntityName; + const nameCandidate = getNameOfSymbolAsWritten(symbol, context); + context.flags = flags; + localName = nameCandidate.length > 0 && isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? stripQuotes(nameCandidate) : nameCandidate; + } + if (localName === InternalSymbolName.Default) { + localName = "_default"; + } + else if (localName === InternalSymbolName.ExportEquals) { + localName = "_exports"; + } + localName = isIdentifierText(localName, languageVersion) && !isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_"); + return localName; + } + + function getInternalSymbolName(symbol: Symbol, localName: string) { + const id = getSymbolId(symbol); + if (context.remappedSymbolNames!.has(id)) { + return context.remappedSymbolNames!.get(id)!; + } + localName = getNameCandidateWorker(symbol, localName); + // The result of this is going to be used as the symbol's name - lock it in, so `getUnusedName` will also pick it up + context.remappedSymbolNames!.set(id, localName); + return localName; + } + } + } + + function typePredicateToString(typePredicate: TypePredicate, enclosingDeclaration?: Node, flags: TypeFormatFlags = TypeFormatFlags.UseAliasDefinedOutsideCurrentScope, writer?: EmitTextWriter): string { + return writer ? typePredicateToStringWorker(writer).getText() : usingSingleLineStringWriter(typePredicateToStringWorker); + + function typePredicateToStringWorker(writer: EmitTextWriter) { + const nodeBuilderFlags = toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.WriteTypeParametersInQualifiedName; + const predicate = nodeBuilder.typePredicateToTypePredicateNode(typePredicate, enclosingDeclaration, nodeBuilderFlags)!; // TODO: GH#18217 + const printer = createPrinterWithRemoveComments(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, predicate, /*sourceFile*/ sourceFile, writer); + return writer; + } + } + + function formatUnionTypes(types: readonly Type[]): Type[] { + const result: Type[] = []; + let flags = 0 as TypeFlags; + for (let i = 0; i < types.length; i++) { + const t = types[i]; + flags |= t.flags; + if (!(t.flags & TypeFlags.Nullable)) { + if (t.flags & (TypeFlags.BooleanLiteral | TypeFlags.EnumLike)) { + const baseType = t.flags & TypeFlags.BooleanLiteral ? booleanType : getBaseTypeOfEnumLikeType(t as LiteralType); + if (baseType.flags & TypeFlags.Union) { + const count = (baseType as UnionType).types.length; + if (i + count <= types.length && getRegularTypeOfLiteralType(types[i + count - 1]) === getRegularTypeOfLiteralType((baseType as UnionType).types[count - 1])) { + result.push(baseType); + i += count - 1; + continue; + } + } + } + result.push(t); + } + } + if (flags & TypeFlags.Null) result.push(nullType); + if (flags & TypeFlags.Undefined) result.push(undefinedType); + return result || types; + } + + function visibilityToString(flags: ModifierFlags): string { + if (flags === ModifierFlags.Private) { + return "private"; + } + if (flags === ModifierFlags.Protected) { + return "protected"; + } + return "public"; + } + + function getTypeAliasForTypeLiteral(type: Type): Symbol | undefined { + if (type.symbol && type.symbol.flags & SymbolFlags.TypeLiteral && type.symbol.declarations) { + const node = walkUpParenthesizedTypes(type.symbol.declarations[0].parent); + if (isTypeAliasDeclaration(node)) { + return getSymbolOfDeclaration(node); + } + } + return undefined; + } + + function isTopLevelInExternalModuleAugmentation(node: Node): boolean { + return node && node.parent && + node.parent.kind === SyntaxKind.ModuleBlock && + isExternalModuleAugmentation(node.parent.parent); + } + + function isDefaultBindingContext(location: Node) { + return location.kind === SyntaxKind.SourceFile || isAmbientModule(location); + } + + function getNameOfSymbolFromNameType(symbol: Symbol, context?: NodeBuilderContext) { + const nameType = getSymbolLinks(symbol).nameType; + if (nameType) { + if (nameType.flags & TypeFlags.StringOrNumberLiteral) { + const name = "" + (nameType as StringLiteralType | NumberLiteralType).value; + if (!isIdentifierText(name, getEmitScriptTarget(compilerOptions)) && !isNumericLiteralName(name)) { + return `"${escapeString(name, CharacterCodes.doubleQuote)}"`; + } + if (isNumericLiteralName(name) && startsWith(name, "-")) { + return `[${name}]`; + } + return name; + } + if (nameType.flags & TypeFlags.UniqueESSymbol) { + return `[${getNameOfSymbolAsWritten((nameType as UniqueESSymbolType).symbol, context)}]`; + } + } + } + + /** + * Gets a human-readable name for a symbol. + * Should *not* be used for the right-hand side of a `.` -- use `symbolName(symbol)` for that instead. + * + * Unlike `symbolName(symbol)`, this will include quotes if the name is from a string literal. + * It will also use a representation of a number as written instead of a decimal form, e.g. `0o11` instead of `9`. + */ + function getNameOfSymbolAsWritten(symbol: Symbol, context?: NodeBuilderContext): string { + if (context?.remappedSymbolReferences?.has(getSymbolId(symbol))) { + symbol = context.remappedSymbolReferences.get(getSymbolId(symbol))!; + } + if ( + context && symbol.escapedName === InternalSymbolName.Default && !(context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope) && + // If it's not the first part of an entity name, it must print as `default` + (!(context.flags & NodeBuilderFlags.InInitialEntityName) || + // if the symbol is synthesized, it will only be referenced externally it must print as `default` + !symbol.declarations || + // if not in the same binding context (source file, module declaration), it must print as `default` + (context.enclosingDeclaration && findAncestor(symbol.declarations[0], isDefaultBindingContext) !== findAncestor(context.enclosingDeclaration, isDefaultBindingContext))) + ) { + return "default"; + } + if (symbol.declarations && symbol.declarations.length) { + let declaration = firstDefined(symbol.declarations, d => getNameOfDeclaration(d) ? d : undefined); // Try using a declaration with a name, first + const name = declaration && getNameOfDeclaration(declaration); + if (declaration && name) { + if (isCallExpression(declaration) && isBindableObjectDefinePropertyCall(declaration)) { + return symbolName(symbol); + } + if (isComputedPropertyName(name) && !(getCheckFlags(symbol) & CheckFlags.Late)) { + const nameType = getSymbolLinks(symbol).nameType; + if (nameType && nameType.flags & TypeFlags.StringOrNumberLiteral) { + // Computed property name isn't late bound, but has a well-known name type - use name type to generate a symbol name + const result = getNameOfSymbolFromNameType(symbol, context); + if (result !== undefined) { + return result; + } + } + } + return declarationNameToString(name); + } + if (!declaration) { + declaration = symbol.declarations[0]; // Declaration may be nameless, but we'll try anyway + } + if (declaration.parent && declaration.parent.kind === SyntaxKind.VariableDeclaration) { + return declarationNameToString((declaration.parent as VariableDeclaration).name); + } + switch (declaration.kind) { + case SyntaxKind.ClassExpression: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + if (context && !context.encounteredError && !(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier)) { + context.encounteredError = true; + } + return declaration.kind === SyntaxKind.ClassExpression ? "(Anonymous class)" : "(Anonymous function)"; + } + } + const name = getNameOfSymbolFromNameType(symbol, context); + return name !== undefined ? name : symbolName(symbol); + } + + function isDeclarationVisible(node: Node): boolean { + if (node) { + const links = getNodeLinks(node); + if (links.isVisible === undefined) { + links.isVisible = !!determineIfDeclarationIsVisible(); + } + return links.isVisible; + } + + return false; + + function determineIfDeclarationIsVisible() { + switch (node.kind) { + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocEnumTag: + // Top-level jsdoc type aliases are considered exported + // First parent is comment node, second is hosting declaration or token; we only care about those tokens or declarations whose parent is a source file + return !!(node.parent && node.parent.parent && node.parent.parent.parent && isSourceFile(node.parent.parent.parent)); + case SyntaxKind.BindingElement: + return isDeclarationVisible(node.parent.parent); + case SyntaxKind.VariableDeclaration: + if ( + isBindingPattern((node as VariableDeclaration).name) && + !((node as VariableDeclaration).name as BindingPattern).elements.length + ) { + // If the binding pattern is empty, this variable declaration is not visible + return false; + } + // falls through + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.ImportEqualsDeclaration: + // external module augmentation is always visible + if (isExternalModuleAugmentation(node)) { + return true; + } + const parent = getDeclarationContainer(node); + // If the node is not exported or it is not ambient module element (except import declaration) + if ( + !(getCombinedModifierFlagsCached(node as Declaration) & ModifierFlags.Export) && + !(node.kind !== SyntaxKind.ImportEqualsDeclaration && parent.kind !== SyntaxKind.SourceFile && parent.flags & NodeFlags.Ambient) + ) { + return isGlobalSourceFile(parent); + } + // Exported members/ambient module elements (exception import declaration) are visible if parent is visible + return isDeclarationVisible(parent); + + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + if (hasEffectiveModifier(node, ModifierFlags.Private | ModifierFlags.Protected)) { + // Private/protected properties/methods are not visible + return false; + } + // Public properties/methods are visible if its parents are visible, so: + // falls through + + case SyntaxKind.Constructor: + case SyntaxKind.ConstructSignature: + case SyntaxKind.CallSignature: + case SyntaxKind.IndexSignature: + case SyntaxKind.Parameter: + case SyntaxKind.ModuleBlock: + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.TypeLiteral: + case SyntaxKind.TypeReference: + case SyntaxKind.ArrayType: + case SyntaxKind.TupleType: + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + case SyntaxKind.ParenthesizedType: + case SyntaxKind.NamedTupleMember: + return isDeclarationVisible(node.parent); + + // Default binding, import specifier and namespace import is visible + // only on demand so by default it is not visible + case SyntaxKind.ImportClause: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportSpecifier: + return false; + + // Type parameters are always visible + case SyntaxKind.TypeParameter: + + // Source file and namespace export are always visible + // falls through + case SyntaxKind.SourceFile: + case SyntaxKind.NamespaceExportDeclaration: + return true; + + // Export assignments do not create name bindings outside the module + case SyntaxKind.ExportAssignment: + return false; + + default: + return false; + } + } + } + + function collectLinkedAliases(node: ModuleExportName, setVisibility?: boolean): Node[] | undefined { + let exportSymbol: Symbol | undefined; + if (node.kind !== SyntaxKind.StringLiteral && node.parent && node.parent.kind === SyntaxKind.ExportAssignment) { + exportSymbol = resolveName(node, node, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + } + else if (node.parent.kind === SyntaxKind.ExportSpecifier) { + exportSymbol = getTargetOfExportSpecifier(node.parent as ExportSpecifier, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); + } + let result: Node[] | undefined; + let visited: Set | undefined; + if (exportSymbol) { + visited = new Set(); + visited.add(getSymbolId(exportSymbol)); + buildVisibleNodeList(exportSymbol.declarations); + } + return result; + + function buildVisibleNodeList(declarations: Declaration[] | undefined) { + forEach(declarations, declaration => { + const resultNode = getAnyImportSyntax(declaration) || declaration; + if (setVisibility) { + getNodeLinks(declaration).isVisible = true; + } + else { + result = result || []; + pushIfUnique(result, resultNode); + } + + if (isInternalModuleImportEqualsDeclaration(declaration)) { + // Add the referenced top container visible + const internalModuleReference = declaration.moduleReference as Identifier | QualifiedName; + const firstIdentifier = getFirstIdentifier(internalModuleReference); + const importSymbol = resolveName(declaration, firstIdentifier.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (importSymbol && visited) { + if (tryAddToSet(visited, getSymbolId(importSymbol))) { + buildVisibleNodeList(importSymbol.declarations); + } + } + } + }); + } + } + + /** + * Push an entry on the type resolution stack. If an entry with the given target and the given property name + * is already on the stack, and no entries in between already have a type, then a circularity has occurred. + * In this case, the result values of the existing entry and all entries pushed after it are changed to false, + * and the value false is returned. Otherwise, the new entry is just pushed onto the stack, and true is returned. + * In order to see if the same query has already been done before, the target object and the propertyName both + * must match the one passed in. + * + * @param target The symbol, type, or signature whose type is being queried + * @param propertyName The property name that should be used to query the target for its type + */ + function pushTypeResolution(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): boolean { + const resolutionCycleStartIndex = findResolutionCycleStartIndex(target, propertyName); + if (resolutionCycleStartIndex >= 0) { + // A cycle was found + const { length } = resolutionTargets; + for (let i = resolutionCycleStartIndex; i < length; i++) { + resolutionResults[i] = false; + } + return false; + } + resolutionTargets.push(target); + resolutionResults.push(/*items*/ true); + resolutionPropertyNames.push(propertyName); + return true; + } + + function findResolutionCycleStartIndex(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): number { + for (let i = resolutionTargets.length - 1; i >= resolutionStart; i--) { + if (resolutionTargetHasProperty(resolutionTargets[i], resolutionPropertyNames[i])) { + return -1; + } + if (resolutionTargets[i] === target && resolutionPropertyNames[i] === propertyName) { + return i; + } + } + return -1; + } + + function resolutionTargetHasProperty(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): boolean { + switch (propertyName) { + case TypeSystemPropertyName.Type: + return !!getSymbolLinks(target as Symbol).type; + case TypeSystemPropertyName.DeclaredType: + return !!getSymbolLinks(target as Symbol).declaredType; + case TypeSystemPropertyName.ResolvedBaseConstructorType: + return !!(target as InterfaceType).resolvedBaseConstructorType; + case TypeSystemPropertyName.ResolvedReturnType: + return !!(target as Signature).resolvedReturnType; + case TypeSystemPropertyName.ImmediateBaseConstraint: + return !!(target as Type).immediateBaseConstraint; + case TypeSystemPropertyName.ResolvedTypeArguments: + return !!(target as TypeReference).resolvedTypeArguments; + case TypeSystemPropertyName.ResolvedBaseTypes: + return !!(target as InterfaceType).baseTypesResolved; + case TypeSystemPropertyName.WriteType: + return !!getSymbolLinks(target as Symbol).writeType; + case TypeSystemPropertyName.ParameterInitializerContainsUndefined: + return getNodeLinks(target as ParameterDeclaration).parameterInitializerContainsUndefined !== undefined; + } + return Debug.assertNever(propertyName); + } + + /** + * Pop an entry from the type resolution stack and return its associated result value. The result value will + * be true if no circularities were detected, or false if a circularity was found. + */ + function popTypeResolution(): boolean { + resolutionTargets.pop(); + resolutionPropertyNames.pop(); + return resolutionResults.pop()!; + } + + function getDeclarationContainer(node: Node): Node { + return findAncestor(getRootDeclaration(node), node => { + switch (node.kind) { + case SyntaxKind.VariableDeclaration: + case SyntaxKind.VariableDeclarationList: + case SyntaxKind.ImportSpecifier: + case SyntaxKind.NamedImports: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportClause: + return false; + default: + return true; + } + })!.parent; + } + + function getTypeOfPrototypeProperty(prototype: Symbol): Type { + // TypeScript 1.0 spec (April 2014): 8.4 + // Every class automatically contains a static property member named 'prototype', + // the type of which is an instantiation of the class type with type Any supplied as a type argument for each type parameter. + // It is an error to explicitly declare a static property member with the name 'prototype'. + const classType = getDeclaredTypeOfSymbol(getParentOfSymbol(prototype)!) as InterfaceType; + return classType.typeParameters ? createTypeReference(classType as GenericType, map(classType.typeParameters, _ => anyType)) : classType; + } + + // Return the type of the given property in the given type, or undefined if no such property exists + function getTypeOfPropertyOfType(type: Type, name: __String): Type | undefined { + const prop = getPropertyOfType(type, name); + return prop ? getTypeOfSymbol(prop) : undefined; + } + + /** + * Return the type of the matching property or index signature in the given type, or undefined + * if no matching property or index signature exists. Add optionality to index signature types. + */ + function getTypeOfPropertyOrIndexSignatureOfType(type: Type, name: __String): Type | undefined { + let propType; + return getTypeOfPropertyOfType(type, name) || + (propType = getApplicableIndexInfoForName(type, name)?.type) && + addOptionality(propType, /*isProperty*/ true, /*isOptional*/ true); + } + + function isTypeAny(type: Type | undefined) { + return type && (type.flags & TypeFlags.Any) !== 0; + } + + function isErrorType(type: Type) { + // The only 'any' types that have alias symbols are those manufactured by getTypeFromTypeAliasReference for + // a reference to an unresolved symbol. We want those to behave like the errorType. + return type === errorType || !!(type.flags & TypeFlags.Any && type.aliasSymbol); + } + + // Return the type of a binding element parent. We check SymbolLinks first to see if a type has been + // assigned by contextual typing. + function getTypeForBindingElementParent(node: BindingElementGrandparent, checkMode: CheckMode) { + if (checkMode !== CheckMode.Normal) { + return getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ false, checkMode); + } + const symbol = getSymbolOfDeclaration(node); + return symbol && getSymbolLinks(symbol).type || getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ false, checkMode); + } + + function getRestType(source: Type, properties: PropertyName[], symbol: Symbol | undefined): Type { + source = filterType(source, t => !(t.flags & TypeFlags.Nullable)); + if (source.flags & TypeFlags.Never) { + return emptyObjectType; + } + if (source.flags & TypeFlags.Union) { + return mapType(source, t => getRestType(t, properties, symbol)); + } + + let omitKeyType = getUnionType(map(properties, getLiteralTypeFromPropertyName)); + + const spreadableProperties: Symbol[] = []; + const unspreadableToRestKeys: Type[] = []; + + for (const prop of getPropertiesOfType(source)) { + const literalTypeFromProperty = getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique); + if ( + !isTypeAssignableTo(literalTypeFromProperty, omitKeyType) + && !(getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) + && isSpreadableProperty(prop) + ) { + spreadableProperties.push(prop); + } + else { + unspreadableToRestKeys.push(literalTypeFromProperty); + } + } + + if (isGenericObjectType(source) || isGenericIndexType(omitKeyType)) { + if (unspreadableToRestKeys.length) { + // If the type we're spreading from has properties that cannot + // be spread into the rest type (e.g. getters, methods), ensure + // they are explicitly omitted, as they would in the non-generic case. + omitKeyType = getUnionType([omitKeyType, ...unspreadableToRestKeys]); + } + + if (omitKeyType.flags & TypeFlags.Never) { + return source; + } + + const omitTypeAlias = getGlobalOmitSymbol(); + if (!omitTypeAlias) { + return errorType; + } + return getTypeAliasInstantiation(omitTypeAlias, [source, omitKeyType]); + } + const members = createSymbolTable(); + for (const prop of spreadableProperties) { + members.set(prop.escapedName, getSpreadSymbol(prop, /*readonly*/ false)); + } + const result = createAnonymousType(symbol, members, emptyArray, emptyArray, getIndexInfosOfType(source)); + result.objectFlags |= ObjectFlags.ObjectRestType; + return result; + } + + function isGenericTypeWithUndefinedConstraint(type: Type) { + return !!(type.flags & TypeFlags.Instantiable) && maybeTypeOfKind(getBaseConstraintOfType(type) || unknownType, TypeFlags.Undefined); + } + + function getNonUndefinedType(type: Type) { + const typeOrConstraint = someType(type, isGenericTypeWithUndefinedConstraint) ? mapType(type, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOrType(t) : t) : type; + return getTypeWithFacts(typeOrConstraint, TypeFacts.NEUndefined); + } + + // Determine the control flow type associated with a destructuring declaration or assignment. The following + // forms of destructuring are possible: + // let { x } = obj; // BindingElement + // let [ x ] = obj; // BindingElement + // { x } = obj; // ShorthandPropertyAssignment + // { x: v } = obj; // PropertyAssignment + // [ x ] = obj; // Expression + // We construct a synthetic element access expression corresponding to 'obj.x' such that the control + // flow analyzer doesn't have to handle all the different syntactic forms. + function getFlowTypeOfDestructuring(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression, declaredType: Type) { + const reference = getSyntheticElementAccess(node); + return reference ? getFlowTypeOfReference(reference, declaredType) : declaredType; + } + + function getSyntheticElementAccess(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression): ElementAccessExpression | undefined { + const parentAccess = getParentElementAccess(node); + if (parentAccess && canHaveFlowNode(parentAccess) && parentAccess.flowNode) { + const propName = getDestructuringPropertyName(node); + if (propName) { + const literal = setTextRangeWorker(parseNodeFactory.createStringLiteral(propName), node); + const lhsExpr = isLeftHandSideExpression(parentAccess) ? parentAccess : parseNodeFactory.createParenthesizedExpression(parentAccess); + const result = setTextRangeWorker(parseNodeFactory.createElementAccessExpression(lhsExpr, literal), node); + setParent(literal, result); + setParent(result, node); + if (lhsExpr !== parentAccess) { + setParent(lhsExpr, result); + } + result.flowNode = parentAccess.flowNode; + return result; + } + } + } + + function getParentElementAccess(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression) { + const ancestor = node.parent.parent; + switch (ancestor.kind) { + case SyntaxKind.BindingElement: + case SyntaxKind.PropertyAssignment: + return getSyntheticElementAccess(ancestor as BindingElement | PropertyAssignment); + case SyntaxKind.ArrayLiteralExpression: + return getSyntheticElementAccess(node.parent as Expression); + case SyntaxKind.VariableDeclaration: + return (ancestor as VariableDeclaration).initializer; + case SyntaxKind.BinaryExpression: + return (ancestor as BinaryExpression).right; + } + } + + function getDestructuringPropertyName(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression) { + const parent = node.parent; + if (node.kind === SyntaxKind.BindingElement && parent.kind === SyntaxKind.ObjectBindingPattern) { + return getLiteralPropertyNameText((node as BindingElement).propertyName || (node as BindingElement).name as Identifier); + } + if (node.kind === SyntaxKind.PropertyAssignment || node.kind === SyntaxKind.ShorthandPropertyAssignment) { + return getLiteralPropertyNameText((node as PropertyAssignment | ShorthandPropertyAssignment).name); + } + return "" + ((parent as BindingPattern | ArrayLiteralExpression).elements as NodeArray).indexOf(node); + } + + function getLiteralPropertyNameText(name: PropertyName) { + const type = getLiteralTypeFromPropertyName(name); + return type.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral) ? "" + (type as StringLiteralType | NumberLiteralType).value : undefined; + } + + /** Return the inferred type for a binding element */ + function getTypeForBindingElement(declaration: BindingElement): Type | undefined { + const checkMode = declaration.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal; + const parentType = getTypeForBindingElementParent(declaration.parent.parent, checkMode); + return parentType && getBindingElementTypeFromParentType(declaration, parentType, /*noTupleBoundsCheck*/ false); + } + + function getBindingElementTypeFromParentType(declaration: BindingElement, parentType: Type, noTupleBoundsCheck: boolean): Type { + // If an any type was inferred for parent, infer that for the binding element + if (isTypeAny(parentType)) { + return parentType; + } + const pattern = declaration.parent; + // Relax null check on ambient destructuring parameters, since the parameters have no implementation and are just documentation + if (strictNullChecks && declaration.flags & NodeFlags.Ambient && isPartOfParameterDeclaration(declaration)) { + parentType = getNonNullableType(parentType); + } + // Filter `undefined` from the type we check against if the parent has an initializer and that initializer is not possibly `undefined` + else if (strictNullChecks && pattern.parent.initializer && !(hasTypeFacts(getTypeOfInitializer(pattern.parent.initializer), TypeFacts.EQUndefined))) { + parentType = getTypeWithFacts(parentType, TypeFacts.NEUndefined); + } + + let type: Type | undefined; + if (pattern.kind === SyntaxKind.ObjectBindingPattern) { + if (declaration.dotDotDotToken) { + parentType = getReducedType(parentType); + if (parentType.flags & TypeFlags.Unknown || !isValidSpreadType(parentType)) { + error(declaration, Diagnostics.Rest_types_may_only_be_created_from_object_types); + return errorType; + } + const literalMembers: PropertyName[] = []; + for (const element of pattern.elements) { + if (!element.dotDotDotToken) { + literalMembers.push(element.propertyName || element.name as Identifier); + } + } + type = getRestType(parentType, literalMembers, declaration.symbol); + } + else { + // Use explicitly specified property name ({ p: xxx } form), or otherwise the implied name ({ p } form) + const name = declaration.propertyName || declaration.name as Identifier; + const indexType = getLiteralTypeFromPropertyName(name); + const declaredType = getIndexedAccessType(parentType, indexType, AccessFlags.ExpressionPosition, name); + type = getFlowTypeOfDestructuring(declaration, declaredType); + } + } + else { + // This elementType will be used if the specific property corresponding to this index is not + // present (aka the tuple element property). This call also checks that the parentType is in + // fact an iterable or array (depending on target language). + const elementType = checkIteratedTypeOrElementType(IterationUse.Destructuring | (declaration.dotDotDotToken ? 0 : IterationUse.PossiblyOutOfBounds), parentType, undefinedType, pattern); + const index = pattern.elements.indexOf(declaration); + if (declaration.dotDotDotToken) { + // If the parent is a tuple type, the rest element has a tuple type of the + // remaining tuple element types. Otherwise, the rest element has an array type with same + // element type as the parent type. + const baseConstraint = mapType(parentType, t => t.flags & TypeFlags.InstantiableNonPrimitive ? getBaseConstraintOrType(t) : t); + type = everyType(baseConstraint, isTupleType) ? + mapType(baseConstraint, t => sliceTupleType(t as TupleTypeReference, index)) : + createArrayType(elementType); + } + else if (isArrayLikeType(parentType)) { + const indexType = getNumberLiteralType(index); + const accessFlags = AccessFlags.ExpressionPosition | (noTupleBoundsCheck || hasDefaultValue(declaration) ? AccessFlags.NoTupleBoundsCheck : 0); + const declaredType = getIndexedAccessTypeOrUndefined(parentType, indexType, accessFlags, declaration.name) || errorType; + type = getFlowTypeOfDestructuring(declaration, declaredType); + } + else { + type = elementType; + } + } + if (!declaration.initializer) { + return type; + } + if (getEffectiveTypeAnnotationNode(walkUpBindingElementsAndPatterns(declaration))) { + // In strict null checking mode, if a default value of a non-undefined type is specified, remove + // undefined from the final type. + return strictNullChecks && !(hasTypeFacts(checkDeclarationInitializer(declaration, CheckMode.Normal), TypeFacts.IsUndefined)) ? getNonUndefinedType(type) : type; + } + return widenTypeInferredFromInitializer(declaration, getUnionType([getNonUndefinedType(type), checkDeclarationInitializer(declaration, CheckMode.Normal)], UnionReduction.Subtype)); + } + + function getTypeForDeclarationFromJSDocComment(declaration: Node) { + const jsdocType = getJSDocType(declaration); + if (jsdocType) { + return getTypeFromTypeNode(jsdocType); + } + return undefined; + } + + function isNullOrUndefined(node: Expression) { + const expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + return expr.kind === SyntaxKind.NullKeyword || expr.kind === SyntaxKind.Identifier && getResolvedSymbol(expr as Identifier) === undefinedSymbol; + } + + function isEmptyArrayLiteral(node: Expression) { + const expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + return expr.kind === SyntaxKind.ArrayLiteralExpression && (expr as ArrayLiteralExpression).elements.length === 0; + } + + function addOptionality(type: Type, isProperty = false, isOptional = true): Type { + return strictNullChecks && isOptional ? getOptionalType(type, isProperty) : type; + } + + // Return the inferred type for a variable, parameter, or property declaration + function getTypeForVariableLikeDeclaration( + declaration: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement | JSDocPropertyLikeTag, + includeOptionality: boolean, + checkMode: CheckMode, + ): Type | undefined { + // A variable declared in a for..in statement is of type string, or of type keyof T when the + // right hand expression is of a type parameter type. + if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForInStatement) { + const indexType = getIndexType(getNonNullableTypeIfNeeded(checkExpression(declaration.parent.parent.expression, /*checkMode*/ checkMode))); + return indexType.flags & (TypeFlags.TypeParameter | TypeFlags.Index) ? getExtractStringType(indexType) : stringType; + } + + if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForOfStatement) { + // checkRightHandSideOfForOf will return undefined if the for-of expression type was + // missing properties/signatures required to get its iteratedType (like + // [Symbol.iterator] or next). This may be because we accessed properties from anyType, + // or it may have led to an error inside getElementTypeOfIterable. + const forOfStatement = declaration.parent.parent; + return checkRightHandSideOfForOf(forOfStatement) || anyType; + } + + if (isBindingPattern(declaration.parent)) { + return getTypeForBindingElement(declaration as BindingElement); + } + + const isProperty = (isPropertyDeclaration(declaration) && !hasAccessorModifier(declaration)) || isPropertySignature(declaration) || isJSDocPropertyTag(declaration); + const isOptional = includeOptionality && isOptionalDeclaration(declaration); + + // Use type from type annotation if one is present + const declaredType = tryGetTypeFromEffectiveTypeNode(declaration); + if (isCatchClauseVariableDeclarationOrBindingElement(declaration)) { + if (declaredType) { + // If the catch clause is explicitly annotated with any or unknown, accept it, otherwise error. + return isTypeAny(declaredType) || declaredType === unknownType ? declaredType : errorType; + } + // If the catch clause is not explicitly annotated, treat it as though it were explicitly + // annotated with unknown or any, depending on useUnknownInCatchVariables. + return useUnknownInCatchVariables ? unknownType : anyType; + } + if (declaredType) { + return addOptionality(declaredType, isProperty, isOptional); + } + + if ( + (noImplicitAny || isInJSFile(declaration)) && + isVariableDeclaration(declaration) && !isBindingPattern(declaration.name) && + !(getCombinedModifierFlagsCached(declaration) & ModifierFlags.Export) && !(declaration.flags & NodeFlags.Ambient) + ) { + // If --noImplicitAny is on or the declaration is in a Javascript file, + // use control flow tracked 'any' type for non-ambient, non-exported var or let variables with no + // initializer or a 'null' or 'undefined' initializer. + if (!(getCombinedNodeFlagsCached(declaration) & NodeFlags.Constant) && (!declaration.initializer || isNullOrUndefined(declaration.initializer))) { + return autoType; + } + // Use control flow tracked 'any[]' type for non-ambient, non-exported variables with an empty array + // literal initializer. + if (declaration.initializer && isEmptyArrayLiteral(declaration.initializer)) { + return autoArrayType; + } + } + + if (isParameter(declaration)) { + if (!declaration.symbol) { + // parameters of function types defined in JSDoc in TS files don't have symbols + return; + } + const func = declaration.parent as FunctionLikeDeclaration; + // For a parameter of a set accessor, use the type of the get accessor if one is present + if (func.kind === SyntaxKind.SetAccessor && hasBindableName(func)) { + const getter = getDeclarationOfKind(getSymbolOfDeclaration(declaration.parent), SyntaxKind.GetAccessor); + if (getter) { + const getterSignature = getSignatureFromDeclaration(getter); + const thisParameter = getAccessorThisParameter(func as AccessorDeclaration); + if (thisParameter && declaration === thisParameter) { + // Use the type from the *getter* + Debug.assert(!thisParameter.type); + return getTypeOfSymbol(getterSignature.thisParameter!); + } + return getReturnTypeOfSignature(getterSignature); + } + } + const parameterTypeOfTypeTag = getParameterTypeOfTypeTag(func, declaration); + if (parameterTypeOfTypeTag) return parameterTypeOfTypeTag; + // Use contextual parameter type if one is available + const type = declaration.symbol.escapedName === InternalSymbolName.This ? getContextualThisParameterType(func) : getContextuallyTypedParameterType(declaration); + if (type) { + return addOptionality(type, /*isProperty*/ false, isOptional); + } + } + + // Use the type of the initializer expression if one is present and the declaration is + // not a parameter of a contextually typed function + if (hasOnlyExpressionInitializer(declaration) && !!declaration.initializer) { + if (isInJSFile(declaration) && !isParameter(declaration)) { + const containerObjectType = getJSContainerObjectType(declaration, getSymbolOfDeclaration(declaration), getDeclaredExpandoInitializer(declaration)); + if (containerObjectType) { + return containerObjectType; + } + } + const type = widenTypeInferredFromInitializer(declaration, checkDeclarationInitializer(declaration, checkMode)); + return addOptionality(type, isProperty, isOptional); + } + + if (isPropertyDeclaration(declaration) && (noImplicitAny || isInJSFile(declaration))) { + // We have a property declaration with no type annotation or initializer, in noImplicitAny mode or a .js file. + // Use control flow analysis of this.xxx assignments in the constructor or static block to determine the type of the property. + if (!hasStaticModifier(declaration)) { + const constructor = findConstructorDeclaration(declaration.parent); + const type = constructor ? getFlowTypeInConstructor(declaration.symbol, constructor) : + getEffectiveModifierFlags(declaration) & ModifierFlags.Ambient ? getTypeOfPropertyInBaseClass(declaration.symbol) : + undefined; + return type && addOptionality(type, /*isProperty*/ true, isOptional); + } + else { + const staticBlocks = filter(declaration.parent.members, isClassStaticBlockDeclaration); + const type = staticBlocks.length ? getFlowTypeInStaticBlocks(declaration.symbol, staticBlocks) : + getEffectiveModifierFlags(declaration) & ModifierFlags.Ambient ? getTypeOfPropertyInBaseClass(declaration.symbol) : + undefined; + return type && addOptionality(type, /*isProperty*/ true, isOptional); + } + } + + if (isJsxAttribute(declaration)) { + // if JSX attribute doesn't have initializer, by default the attribute will have boolean value of true. + // I.e is sugar for + return trueType; + } + + // If the declaration specifies a binding pattern and is not a parameter of a contextually + // typed function, use the type implied by the binding pattern + if (isBindingPattern(declaration.name)) { + return getTypeFromBindingPattern(declaration.name, /*includePatternInType*/ false, /*reportErrors*/ true); + } + + // No type specified and nothing can be inferred + return undefined; + } + + function isConstructorDeclaredProperty(symbol: Symbol) { + // A property is considered a constructor declared property when all declaration sites are this.xxx assignments, + // when no declaration sites have JSDoc type annotations, and when at least one declaration site is in the body of + // a class constructor. + if (symbol.valueDeclaration && isBinaryExpression(symbol.valueDeclaration)) { + const links = getSymbolLinks(symbol); + if (links.isConstructorDeclaredProperty === undefined) { + links.isConstructorDeclaredProperty = false; + links.isConstructorDeclaredProperty = !!getDeclaringConstructor(symbol) && every(symbol.declarations, declaration => + isBinaryExpression(declaration) && + isPossiblyAliasedThisProperty(declaration) && + (declaration.left.kind !== SyntaxKind.ElementAccessExpression || isStringOrNumericLiteralLike((declaration.left as ElementAccessExpression).argumentExpression)) && + !getAnnotatedTypeForAssignmentDeclaration(/*declaredType*/ undefined, declaration, symbol, declaration)); + } + return links.isConstructorDeclaredProperty; + } + return false; + } + + function isAutoTypedProperty(symbol: Symbol) { + // A property is auto-typed when its declaration has no type annotation or initializer and we're in + // noImplicitAny mode or a .js file. + const declaration = symbol.valueDeclaration; + return declaration && isPropertyDeclaration(declaration) && !getEffectiveTypeAnnotationNode(declaration) && + !declaration.initializer && (noImplicitAny || isInJSFile(declaration)); + } + + function getDeclaringConstructor(symbol: Symbol) { + if (!symbol.declarations) { + return; + } + for (const declaration of symbol.declarations) { + const container = getThisContainer(declaration, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (container && (container.kind === SyntaxKind.Constructor || isJSConstructor(container))) { + return container as ConstructorDeclaration; + } + } + } + + /** Create a synthetic property access flow node after the last statement of the file */ + function getFlowTypeFromCommonJSExport(symbol: Symbol) { + const file = getSourceFileOfNode(symbol.declarations![0]); + const accessName = unescapeLeadingUnderscores(symbol.escapedName); + const areAllModuleExports = symbol.declarations!.every(d => isInJSFile(d) && isAccessExpression(d) && isModuleExportsAccessExpression(d.expression)); + const reference = areAllModuleExports + ? factory.createPropertyAccessExpression(factory.createPropertyAccessExpression(factory.createIdentifier("module"), factory.createIdentifier("exports")), accessName) + : factory.createPropertyAccessExpression(factory.createIdentifier("exports"), accessName); + if (areAllModuleExports) { + setParent((reference.expression as PropertyAccessExpression).expression, reference.expression); + } + setParent(reference.expression, reference); + setParent(reference, file); + reference.flowNode = file.endFlowNode; + return getFlowTypeOfReference(reference, autoType, undefinedType); + } + + function getFlowTypeInStaticBlocks(symbol: Symbol, staticBlocks: readonly ClassStaticBlockDeclaration[]) { + const accessName = startsWith(symbol.escapedName as string, "__#") + ? factory.createPrivateIdentifier((symbol.escapedName as string).split("@")[1]) + : unescapeLeadingUnderscores(symbol.escapedName); + for (const staticBlock of staticBlocks) { + const reference = factory.createPropertyAccessExpression(factory.createThis(), accessName); + setParent(reference.expression, reference); + setParent(reference, staticBlock); + reference.flowNode = staticBlock.returnFlowNode; + const flowType = getFlowTypeOfProperty(reference, symbol); + if (noImplicitAny && (flowType === autoType || flowType === autoArrayType)) { + error(symbol.valueDeclaration, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); + } + // We don't infer a type if assignments are only null or undefined. + if (everyType(flowType, isNullableType)) { + continue; + } + return convertAutoToAny(flowType); + } + } + + function getFlowTypeInConstructor(symbol: Symbol, constructor: ConstructorDeclaration) { + const accessName = startsWith(symbol.escapedName as string, "__#") + ? factory.createPrivateIdentifier((symbol.escapedName as string).split("@")[1]) + : unescapeLeadingUnderscores(symbol.escapedName); + const reference = factory.createPropertyAccessExpression(factory.createThis(), accessName); + setParent(reference.expression, reference); + setParent(reference, constructor); + reference.flowNode = constructor.returnFlowNode; + const flowType = getFlowTypeOfProperty(reference, symbol); + if (noImplicitAny && (flowType === autoType || flowType === autoArrayType)) { + error(symbol.valueDeclaration, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); + } + // We don't infer a type if assignments are only null or undefined. + return everyType(flowType, isNullableType) ? undefined : convertAutoToAny(flowType); + } + + function getFlowTypeOfProperty(reference: Node, prop: Symbol | undefined) { + const initialType = prop?.valueDeclaration + && (!isAutoTypedProperty(prop) || getEffectiveModifierFlags(prop.valueDeclaration) & ModifierFlags.Ambient) + && getTypeOfPropertyInBaseClass(prop) + || undefinedType; + return getFlowTypeOfReference(reference, autoType, initialType); + } + + function getWidenedTypeForAssignmentDeclaration(symbol: Symbol, resolvedSymbol?: Symbol) { + // function/class/{} initializers are themselves containers, so they won't merge in the same way as other initializers + const container = getAssignedExpandoInitializer(symbol.valueDeclaration); + if (container) { + const tag = isInJSFile(container) ? getJSDocTypeTag(container) : undefined; + if (tag && tag.typeExpression) { + return getTypeFromTypeNode(tag.typeExpression); + } + const containerObjectType = symbol.valueDeclaration && getJSContainerObjectType(symbol.valueDeclaration, symbol, container); + return containerObjectType || getWidenedLiteralType(checkExpressionCached(container)); + } + let type; + let definedInConstructor = false; + let definedInMethod = false; + // We use control flow analysis to determine the type of the property if the property qualifies as a constructor + // declared property and the resulting control flow type isn't just undefined or null. + if (isConstructorDeclaredProperty(symbol)) { + type = getFlowTypeInConstructor(symbol, getDeclaringConstructor(symbol)!); + } + if (!type) { + let types: Type[] | undefined; + if (symbol.declarations) { + let jsdocType: Type | undefined; + for (const declaration of symbol.declarations) { + const expression = (isBinaryExpression(declaration) || isCallExpression(declaration)) ? declaration : + isAccessExpression(declaration) ? isBinaryExpression(declaration.parent) ? declaration.parent : declaration : + undefined; + if (!expression) { + continue; // Non-assignment declaration merged in (eg, an Identifier to mark the thing as a namespace) - skip over it and pull type info from elsewhere + } + + const kind = isAccessExpression(expression) + ? getAssignmentDeclarationPropertyAccessKind(expression) + : getAssignmentDeclarationKind(expression); + if (kind === AssignmentDeclarationKind.ThisProperty || isBinaryExpression(expression) && isPossiblyAliasedThisProperty(expression, kind)) { + if (isDeclarationInConstructor(expression)) { + definedInConstructor = true; + } + else { + definedInMethod = true; + } + } + if (!isCallExpression(expression)) { + jsdocType = getAnnotatedTypeForAssignmentDeclaration(jsdocType, expression, symbol, declaration); + } + if (!jsdocType) { + (types || (types = [])).push((isBinaryExpression(expression) || isCallExpression(expression)) ? getInitializerTypeFromAssignmentDeclaration(symbol, resolvedSymbol, expression, kind) : neverType); + } + } + type = jsdocType; + } + if (!type) { + if (!length(types)) { + return errorType; // No types from any declarations :( + } + let constructorTypes = definedInConstructor && symbol.declarations ? getConstructorDefinedThisAssignmentTypes(types!, symbol.declarations) : undefined; + // use only the constructor types unless they were only assigned null | undefined (including widening variants) + if (definedInMethod) { + const propType = getTypeOfPropertyInBaseClass(symbol); + if (propType) { + (constructorTypes || (constructorTypes = [])).push(propType); + definedInConstructor = true; + } + } + const sourceTypes = some(constructorTypes, t => !!(t.flags & ~TypeFlags.Nullable)) ? constructorTypes : types; // TODO: GH#18217 + type = getUnionType(sourceTypes!); + } + } + const widened = getWidenedType(addOptionality(type, /*isProperty*/ false, definedInMethod && !definedInConstructor)); + if (symbol.valueDeclaration && isInJSFile(symbol.valueDeclaration) && filterType(widened, t => !!(t.flags & ~TypeFlags.Nullable)) === neverType) { + reportImplicitAny(symbol.valueDeclaration, anyType); + return anyType; + } + return widened; + } + + function getJSContainerObjectType(decl: Node, symbol: Symbol, init: Expression | undefined): Type | undefined { + if (!isInJSFile(decl) || !init || !isObjectLiteralExpression(init) || init.properties.length) { + return undefined; + } + const exports = createSymbolTable(); + while (isBinaryExpression(decl) || isPropertyAccessExpression(decl)) { + const s = getSymbolOfNode(decl); + if (s?.exports?.size) { + mergeSymbolTable(exports, s.exports); + } + decl = isBinaryExpression(decl) ? decl.parent : decl.parent.parent; + } + const s = getSymbolOfNode(decl); + if (s?.exports?.size) { + mergeSymbolTable(exports, s.exports); + } + const type = createAnonymousType(symbol, exports, emptyArray, emptyArray, emptyArray); + type.objectFlags |= ObjectFlags.JSLiteral; + return type; + } + + function getAnnotatedTypeForAssignmentDeclaration(declaredType: Type | undefined, expression: Expression, symbol: Symbol, declaration: Declaration) { + const typeNode = getEffectiveTypeAnnotationNode(expression.parent); + if (typeNode) { + const type = getWidenedType(getTypeFromTypeNode(typeNode)); + if (!declaredType) { + return type; + } + else if (!isErrorType(declaredType) && !isErrorType(type) && !isTypeIdenticalTo(declaredType, type)) { + errorNextVariableOrPropertyDeclarationMustHaveSameType(/*firstDeclaration*/ undefined, declaredType, declaration, type); + } + } + if (symbol.parent?.valueDeclaration) { + const possiblyAnnotatedSymbol = getFunctionExpressionParentSymbolOrSymbol(symbol.parent); + if (possiblyAnnotatedSymbol.valueDeclaration) { + const typeNode = getEffectiveTypeAnnotationNode(possiblyAnnotatedSymbol.valueDeclaration); + if (typeNode) { + const annotationSymbol = getPropertyOfType(getTypeFromTypeNode(typeNode), symbol.escapedName); + if (annotationSymbol) { + return getNonMissingTypeOfSymbol(annotationSymbol); + } + } + } + } + + return declaredType; + } + + /** If we don't have an explicit JSDoc type, get the type from the initializer. */ + function getInitializerTypeFromAssignmentDeclaration(symbol: Symbol, resolvedSymbol: Symbol | undefined, expression: BinaryExpression | CallExpression, kind: AssignmentDeclarationKind) { + if (isCallExpression(expression)) { + if (resolvedSymbol) { + return getTypeOfSymbol(resolvedSymbol); // This shouldn't happen except under some hopefully forbidden merges of export assignments and object define assignments + } + const objectLitType = checkExpressionCached((expression as BindableObjectDefinePropertyCall).arguments[2]); + const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String); + if (valueType) { + return valueType; + } + const getFunc = getTypeOfPropertyOfType(objectLitType, "get" as __String); + if (getFunc) { + const getSig = getSingleCallSignature(getFunc); + if (getSig) { + return getReturnTypeOfSignature(getSig); + } + } + const setFunc = getTypeOfPropertyOfType(objectLitType, "set" as __String); + if (setFunc) { + const setSig = getSingleCallSignature(setFunc); + if (setSig) { + return getTypeOfFirstParameterOfSignature(setSig); + } + } + return anyType; + } + if (containsSameNamedThisProperty(expression.left, expression.right)) { + return anyType; + } + const isDirectExport = kind === AssignmentDeclarationKind.ExportsProperty && (isPropertyAccessExpression(expression.left) || isElementAccessExpression(expression.left)) && (isModuleExportsAccessExpression(expression.left.expression) || (isIdentifier(expression.left.expression) && isExportsIdentifier(expression.left.expression))); + const type = resolvedSymbol ? getTypeOfSymbol(resolvedSymbol) + : isDirectExport ? getRegularTypeOfLiteralType(checkExpressionCached(expression.right)) + : getWidenedLiteralType(checkExpressionCached(expression.right)); + if ( + type.flags & TypeFlags.Object && + kind === AssignmentDeclarationKind.ModuleExports && + symbol.escapedName === InternalSymbolName.ExportEquals + ) { + const exportedType = resolveStructuredTypeMembers(type as ObjectType); + const members = createSymbolTable(); + copyEntries(exportedType.members, members); + const initialSize = members.size; + if (resolvedSymbol && !resolvedSymbol.exports) { + resolvedSymbol.exports = createSymbolTable(); + } + (resolvedSymbol || symbol).exports!.forEach((s, name) => { + const exportedMember = members.get(name)!; + if (exportedMember && exportedMember !== s && !(s.flags & SymbolFlags.Alias)) { + if (s.flags & SymbolFlags.Value && exportedMember.flags & SymbolFlags.Value) { + // If the member has an additional value-like declaration, union the types from the two declarations, + // but issue an error if they occurred in two different files. The purpose is to support a JS file with + // a pattern like: + // + // module.exports = { a: true }; + // module.exports.a = 3; + // + // but we may have a JS file with `module.exports = { a: true }` along with a TypeScript module augmentation + // declaring an `export const a: number`. In that case, we issue a duplicate identifier error, because + // it's unclear what that's supposed to mean, so it's probably a mistake. + if (s.valueDeclaration && exportedMember.valueDeclaration && getSourceFileOfNode(s.valueDeclaration) !== getSourceFileOfNode(exportedMember.valueDeclaration)) { + const unescapedName = unescapeLeadingUnderscores(s.escapedName); + const exportedMemberName = tryCast(exportedMember.valueDeclaration, isNamedDeclaration)?.name || exportedMember.valueDeclaration; + addRelatedInfo( + error(s.valueDeclaration, Diagnostics.Duplicate_identifier_0, unescapedName), + createDiagnosticForNode(exportedMemberName, Diagnostics._0_was_also_declared_here, unescapedName), + ); + addRelatedInfo( + error(exportedMemberName, Diagnostics.Duplicate_identifier_0, unescapedName), + createDiagnosticForNode(s.valueDeclaration, Diagnostics._0_was_also_declared_here, unescapedName), + ); + } + const union = createSymbol(s.flags | exportedMember.flags, name); + union.links.type = getUnionType([getTypeOfSymbol(s), getTypeOfSymbol(exportedMember)]); + union.valueDeclaration = exportedMember.valueDeclaration; + union.declarations = concatenate(exportedMember.declarations, s.declarations); + members.set(name, union); + } + else { + members.set(name, mergeSymbol(s, exportedMember)); + } + } + else { + members.set(name, s); + } + }); + const result = createAnonymousType( + initialSize !== members.size ? undefined : exportedType.symbol, // Only set the type's symbol if it looks to be the same as the original type + members, + exportedType.callSignatures, + exportedType.constructSignatures, + exportedType.indexInfos, + ); + if (initialSize === members.size) { + if (type.aliasSymbol) { + result.aliasSymbol = type.aliasSymbol; + result.aliasTypeArguments = type.aliasTypeArguments; + } + if (getObjectFlags(type) & ObjectFlags.Reference) { + result.aliasSymbol = (type as TypeReference).symbol; + const args = getTypeArguments(type as TypeReference); + result.aliasTypeArguments = length(args) ? args : undefined; + } + } + result.objectFlags |= getPropagatingFlagsOfTypes([type]) | getObjectFlags(type) & (ObjectFlags.JSLiteral | ObjectFlags.ArrayLiteral | ObjectFlags.ObjectLiteral); + if (result.symbol && result.symbol.flags & SymbolFlags.Class && type === getDeclaredTypeOfClassOrInterface(result.symbol)) { + result.objectFlags |= ObjectFlags.IsClassInstanceClone; // Propagate the knowledge that this type is equivalent to the symbol's class instance type + } + return result; + } + if (isEmptyArrayLiteralType(type)) { + reportImplicitAny(expression, anyArrayType); + return anyArrayType; + } + return type; + } + + function containsSameNamedThisProperty(thisProperty: Expression, expression: Expression) { + return isPropertyAccessExpression(thisProperty) + && thisProperty.expression.kind === SyntaxKind.ThisKeyword + && forEachChildRecursively(expression, n => isMatchingReference(thisProperty, n)); + } + + function isDeclarationInConstructor(expression: Expression) { + const thisContainer = getThisContainer(expression, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + // Properties defined in a constructor (or base constructor, or javascript constructor function) don't get undefined added. + // Function expressions that are assigned to the prototype count as methods. + return thisContainer.kind === SyntaxKind.Constructor || + thisContainer.kind === SyntaxKind.FunctionDeclaration || + (thisContainer.kind === SyntaxKind.FunctionExpression && !isPrototypePropertyAssignment(thisContainer.parent)); + } + + function getConstructorDefinedThisAssignmentTypes(types: Type[], declarations: Declaration[]): Type[] | undefined { + Debug.assert(types.length === declarations.length); + return types.filter((_, i) => { + const declaration = declarations[i]; + const expression = isBinaryExpression(declaration) ? declaration : + isBinaryExpression(declaration.parent) ? declaration.parent : undefined; + return expression && isDeclarationInConstructor(expression); + }); + } + + // Return the type implied by a binding pattern element. This is the type of the initializer of the element if + // one is present. Otherwise, if the element is itself a binding pattern, it is the type implied by the binding + // pattern. Otherwise, it is the type any. + function getTypeFromBindingElement(element: BindingElement, includePatternInType?: boolean, reportErrors?: boolean): Type { + if (element.initializer) { + // The type implied by a binding pattern is independent of context, so we check the initializer with no + // contextual type or, if the element itself is a binding pattern, with the type implied by that binding + // pattern. + const contextualType = isBindingPattern(element.name) ? getTypeFromBindingPattern(element.name, /*includePatternInType*/ true, /*reportErrors*/ false) : unknownType; + return addOptionality(widenTypeInferredFromInitializer(element, checkDeclarationInitializer(element, reportErrors ? CheckMode.Normal : CheckMode.Contextual, contextualType))); + } + if (isBindingPattern(element.name)) { + return getTypeFromBindingPattern(element.name, includePatternInType, reportErrors); + } + if (reportErrors && !declarationBelongsToPrivateAmbientMember(element)) { + reportImplicitAny(element, anyType); + } + // When we're including the pattern in the type (an indication we're obtaining a contextual type), we + // use a non-inferrable any type. Inference will never directly infer this type, but it is possible + // to infer a type that contains it, e.g. for a binding pattern like [foo] or { foo }. In such cases, + // widening of the binding pattern type substitutes a regular any for the non-inferrable any. + return includePatternInType ? nonInferrableAnyType : anyType; + } + + // Return the type implied by an object binding pattern + function getTypeFromObjectBindingPattern(pattern: ObjectBindingPattern, includePatternInType: boolean, reportErrors: boolean): Type { + const members = createSymbolTable(); + let stringIndexInfo: IndexInfo | undefined; + let objectFlags = ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + forEach(pattern.elements, e => { + const name = e.propertyName || e.name as Identifier; + if (e.dotDotDotToken) { + stringIndexInfo = createIndexInfo(stringType, anyType, /*isReadonly*/ false); + return; + } + + const exprType = getLiteralTypeFromPropertyName(name); + if (!isTypeUsableAsPropertyName(exprType)) { + // do not include computed properties in the implied type + objectFlags |= ObjectFlags.ObjectLiteralPatternWithComputedProperties; + return; + } + const text = getPropertyNameFromType(exprType); + const flags = SymbolFlags.Property | (e.initializer ? SymbolFlags.Optional : 0); + const symbol = createSymbol(flags, text); + symbol.links.type = getTypeFromBindingElement(e, includePatternInType, reportErrors); + symbol.links.bindingElement = e; + members.set(symbol.escapedName, symbol); + }); + const result = createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, stringIndexInfo ? [stringIndexInfo] : emptyArray); + result.objectFlags |= objectFlags; + if (includePatternInType) { + result.pattern = pattern; + result.objectFlags |= ObjectFlags.ContainsObjectOrArrayLiteral; + } + return result; + } + + // Return the type implied by an array binding pattern + function getTypeFromArrayBindingPattern(pattern: BindingPattern, includePatternInType: boolean, reportErrors: boolean): Type { + const elements = pattern.elements; + const lastElement = lastOrUndefined(elements); + const restElement = lastElement && lastElement.kind === SyntaxKind.BindingElement && lastElement.dotDotDotToken ? lastElement : undefined; + if (elements.length === 0 || elements.length === 1 && restElement) { + return languageVersion >= ScriptTarget.ES2015 ? createIterableType(anyType) : anyArrayType; + } + const elementTypes = map(elements, e => isOmittedExpression(e) ? anyType : getTypeFromBindingElement(e, includePatternInType, reportErrors)); + const minLength = findLastIndex(elements, e => !(e === restElement || isOmittedExpression(e) || hasDefaultValue(e)), elements.length - 1) + 1; + const elementFlags = map(elements, (e, i) => e === restElement ? ElementFlags.Rest : i >= minLength ? ElementFlags.Optional : ElementFlags.Required); + let result = createTupleType(elementTypes, elementFlags) as TypeReference; + if (includePatternInType) { + result = cloneTypeReference(result); + result.pattern = pattern; + result.objectFlags |= ObjectFlags.ContainsObjectOrArrayLiteral; + } + return result; + } + + // Return the type implied by a binding pattern. This is the type implied purely by the binding pattern itself + // and without regard to its context (i.e. without regard any type annotation or initializer associated with the + // declaration in which the binding pattern is contained). For example, the implied type of [x, y] is [any, any] + // and the implied type of { x, y: z = 1 } is { x: any; y: number; }. The type implied by a binding pattern is + // used as the contextual type of an initializer associated with the binding pattern. Also, for a destructuring + // parameter with no type annotation or initializer, the type implied by the binding pattern becomes the type of + // the parameter. + function getTypeFromBindingPattern(pattern: BindingPattern, includePatternInType = false, reportErrors = false): Type { + return pattern.kind === SyntaxKind.ObjectBindingPattern + ? getTypeFromObjectBindingPattern(pattern, includePatternInType, reportErrors) + : getTypeFromArrayBindingPattern(pattern, includePatternInType, reportErrors); + } + + // Return the type associated with a variable, parameter, or property declaration. In the simple case this is the type + // specified in a type annotation or inferred from an initializer. However, in the case of a destructuring declaration it + // is a bit more involved. For example: + // + // var [x, s = ""] = [1, "one"]; + // + // Here, the array literal [1, "one"] is contextually typed by the type [any, string], which is the implied type of the + // binding pattern [x, s = ""]. Because the contextual type is a tuple type, the resulting type of [1, "one"] is the + // tuple type [number, string]. Thus, the type inferred for 'x' is number and the type inferred for 's' is string. + function getWidenedTypeForVariableLikeDeclaration(declaration: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement | JSDocPropertyLikeTag, reportErrors?: boolean): Type { + return widenTypeForVariableLikeDeclaration(getTypeForVariableLikeDeclaration(declaration, /*includeOptionality*/ true, CheckMode.Normal), declaration, reportErrors); + } + + function getTypeFromImportAttributes(node: ImportAttributes): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const symbol = createSymbol(SymbolFlags.ObjectLiteral, InternalSymbolName.ImportAttributes); + const members = createSymbolTable(); + forEach(node.elements, attr => { + const member = createSymbol(SymbolFlags.Property, getNameFromImportAttribute(attr)); + member.parent = symbol; + member.links.type = checkImportAttribute(attr); + member.links.target = member; + members.set(member.escapedName, member); + }); + const type = createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + type.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.NonInferrableType; + links.resolvedType = type; + } + return links.resolvedType; + } + + function isGlobalSymbolConstructor(node: Node) { + const symbol = getSymbolOfNode(node); + const globalSymbol = getGlobalESSymbolConstructorTypeSymbol(/*reportErrors*/ false); + return globalSymbol && symbol && symbol === globalSymbol; + } + + function widenTypeForVariableLikeDeclaration(type: Type | undefined, declaration: any, reportErrors?: boolean) { + if (type) { + // TODO: If back compat with pre-3.0/4.0 libs isn't required, remove the following SymbolConstructor special case transforming `symbol` into `unique symbol` + if (type.flags & TypeFlags.ESSymbol && isGlobalSymbolConstructor(declaration.parent)) { + type = getESSymbolLikeTypeForNode(declaration); + } + if (reportErrors) { + reportErrorsFromWidening(declaration, type); + } + + // always widen a 'unique symbol' type if the type was created for a different declaration. + if (type.flags & TypeFlags.UniqueESSymbol && (isBindingElement(declaration) || !declaration.type) && type.symbol !== getSymbolOfDeclaration(declaration)) { + type = esSymbolType; + } + + return getWidenedType(type); + } + + // Rest parameters default to type any[], other parameters default to type any + type = isParameter(declaration) && declaration.dotDotDotToken ? anyArrayType : anyType; + + // Report implicit any errors unless this is a private property within an ambient declaration + if (reportErrors) { + if (!declarationBelongsToPrivateAmbientMember(declaration)) { + reportImplicitAny(declaration, type); + } + } + return type; + } + + function declarationBelongsToPrivateAmbientMember(declaration: VariableLikeDeclaration) { + const root = getRootDeclaration(declaration); + const memberDeclaration = root.kind === SyntaxKind.Parameter ? root.parent : root; + return isPrivateWithinAmbient(memberDeclaration); + } + + function tryGetTypeFromEffectiveTypeNode(node: Node) { + const typeNode = getEffectiveTypeAnnotationNode(node); + if (typeNode) { + return getTypeFromTypeNode(typeNode); + } + } + + function isParameterOfContextSensitiveSignature(symbol: Symbol) { + let decl = symbol.valueDeclaration; + if (!decl) { + return false; + } + if (isBindingElement(decl)) { + decl = walkUpBindingElementsAndPatterns(decl); + } + if (isParameter(decl)) { + return isContextSensitiveFunctionOrObjectLiteralMethod(decl.parent); + } + return false; + } + + function getTypeOfVariableOrParameterOrProperty(symbol: Symbol, checkMode?: CheckMode): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + const type = getTypeOfVariableOrParameterOrPropertyWorker(symbol, checkMode); + // For a contextually typed parameter it is possible that a type has already + // been assigned (in assignTypeToParameterAndFixTypeParameters), and we want + // to preserve this type. In fact, we need to _prefer_ that type, but it won't + // be assigned until contextual typing is complete, so we need to defer in + // cases where contextual typing may take place. + if (!links.type && !isParameterOfContextSensitiveSignature(symbol) && !checkMode) { + links.type = type; + } + return type; + } + return links.type; + } + + function getTypeOfVariableOrParameterOrPropertyWorker(symbol: Symbol, checkMode?: CheckMode): Type { + // Handle prototype property + if (symbol.flags & SymbolFlags.Prototype) { + return getTypeOfPrototypeProperty(symbol); + } + // CommonsJS require and module both have type any. + if (symbol === requireSymbol) { + return anyType; + } + if (symbol.flags & SymbolFlags.ModuleExports && symbol.valueDeclaration) { + const fileSymbol = getSymbolOfDeclaration(getSourceFileOfNode(symbol.valueDeclaration)); + const result = createSymbol(fileSymbol.flags, "exports" as __String); + result.declarations = fileSymbol.declarations ? fileSymbol.declarations.slice() : []; + result.parent = symbol; + result.links.target = fileSymbol; + if (fileSymbol.valueDeclaration) result.valueDeclaration = fileSymbol.valueDeclaration; + if (fileSymbol.members) result.members = new Map(fileSymbol.members); + if (fileSymbol.exports) result.exports = new Map(fileSymbol.exports); + const members = createSymbolTable(); + members.set("exports" as __String, result); + return createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + } + Debug.assertIsDefined(symbol.valueDeclaration); + const declaration = symbol.valueDeclaration; + // Handle export default expressions + if (isSourceFile(declaration) && isJsonSourceFile(declaration)) { + if (!declaration.statements.length) { + return emptyObjectType; + } + return getWidenedType(getWidenedLiteralType(checkExpression(declaration.statements[0].expression))); + } + if (isAccessor(declaration)) { + // Binding of certain patterns in JS code will occasionally mark symbols as both properties + // and accessors. Here we dispatch to accessor resolution if needed. + return getTypeOfAccessors(symbol); + } + + // Handle variable, parameter or property + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` + if (symbol.flags & SymbolFlags.ValueModule && !(symbol.flags & SymbolFlags.Assignment)) { + return getTypeOfFuncClassEnumModule(symbol); + } + + // When trying to get the *contextual* type of a binding element, it's possible to fall in a loop and therefore + // end up in a circularity-like situation. This is not a true circularity so we should not report such an error. + // For example, here the looping could happen when trying to get the type of `a` (binding element): + // + // const { a, b = a } = { a: 0 } + // + if (isBindingElement(declaration) && checkMode === CheckMode.Contextual) { + return errorType; + } + return reportCircularityError(symbol); + } + let type: Type; + if (declaration.kind === SyntaxKind.ExportAssignment) { + type = widenTypeForVariableLikeDeclaration(tryGetTypeFromEffectiveTypeNode(declaration) || checkExpressionCached((declaration as ExportAssignment).expression), declaration); + } + else if ( + isBinaryExpression(declaration) || + (isInJSFile(declaration) && + (isCallExpression(declaration) || (isPropertyAccessExpression(declaration) || isBindableStaticElementAccessExpression(declaration)) && isBinaryExpression(declaration.parent))) + ) { + type = getWidenedTypeForAssignmentDeclaration(symbol); + } + else if ( + isPropertyAccessExpression(declaration) + || isElementAccessExpression(declaration) + || isIdentifier(declaration) + || isStringLiteralLike(declaration) + || isNumericLiteral(declaration) + || isClassDeclaration(declaration) + || isFunctionDeclaration(declaration) + || (isMethodDeclaration(declaration) && !isObjectLiteralMethod(declaration)) + || isMethodSignature(declaration) + || isSourceFile(declaration) + ) { + // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.Enum | SymbolFlags.ValueModule)) { + return getTypeOfFuncClassEnumModule(symbol); + } + type = isBinaryExpression(declaration.parent) ? + getWidenedTypeForAssignmentDeclaration(symbol) : + tryGetTypeFromEffectiveTypeNode(declaration) || anyType; + } + else if (isPropertyAssignment(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkPropertyAssignment(declaration); + } + else if (isJsxAttribute(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkJsxAttribute(declaration); + } + else if (isShorthandPropertyAssignment(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkExpressionForMutableLocation(declaration.name, CheckMode.Normal); + } + else if (isObjectLiteralMethod(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkObjectLiteralMethod(declaration, CheckMode.Normal); + } + else if ( + isParameter(declaration) + || isPropertyDeclaration(declaration) + || isPropertySignature(declaration) + || isVariableDeclaration(declaration) + || isBindingElement(declaration) + || isJSDocPropertyLikeTag(declaration) + ) { + type = getWidenedTypeForVariableLikeDeclaration(declaration, /*reportErrors*/ true); + } + // getTypeOfSymbol dispatches some JS merges incorrectly because their symbol flags are not mutually exclusive. + // Re-dispatch based on valueDeclaration.kind instead. + else if (isEnumDeclaration(declaration)) { + type = getTypeOfFuncClassEnumModule(symbol); + } + else if (isEnumMember(declaration)) { + type = getTypeOfEnumMember(symbol); + } + else { + return Debug.fail("Unhandled declaration kind! " + Debug.formatSyntaxKind(declaration.kind) + " for " + Debug.formatSymbol(symbol)); + } + + if (!popTypeResolution()) { + // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` + if (symbol.flags & SymbolFlags.ValueModule && !(symbol.flags & SymbolFlags.Assignment)) { + return getTypeOfFuncClassEnumModule(symbol); + } + + // When trying to get the *contextual* type of a binding element, it's possible to fall in a loop and therefore + // end up in a circularity-like situation. This is not a true circularity so we should not report such an error. + // For example, here the looping could happen when trying to get the type of `a` (binding element): + // + // const { a, b = a } = { a: 0 } + // + if (isBindingElement(declaration) && checkMode === CheckMode.Contextual) { + return type; + } + return reportCircularityError(symbol); + } + return type; + } + + function getAnnotatedAccessorTypeNode(accessor: AccessorDeclaration | PropertyDeclaration | undefined): TypeNode | undefined { + if (accessor) { + switch (accessor.kind) { + case SyntaxKind.GetAccessor: + const getterTypeAnnotation = getEffectiveReturnTypeNode(accessor); + return getterTypeAnnotation; + case SyntaxKind.SetAccessor: + const setterTypeAnnotation = getEffectiveSetAccessorTypeAnnotationNode(accessor); + return setterTypeAnnotation; + case SyntaxKind.PropertyDeclaration: + Debug.assert(hasAccessorModifier(accessor)); + const accessorTypeAnnotation = getEffectiveTypeAnnotationNode(accessor); + return accessorTypeAnnotation; + } + } + return undefined; + } + + function getAnnotatedAccessorType(accessor: AccessorDeclaration | PropertyDeclaration | undefined): Type | undefined { + const node = getAnnotatedAccessorTypeNode(accessor); + return node && getTypeFromTypeNode(node); + } + + function getAnnotatedAccessorThisParameter(accessor: AccessorDeclaration): Symbol | undefined { + const parameter = getAccessorThisParameter(accessor); + return parameter && parameter.symbol; + } + + function getThisTypeOfDeclaration(declaration: SignatureDeclaration): Type | undefined { + return getThisTypeOfSignature(getSignatureFromDeclaration(declaration)); + } + + function getTypeOfAccessors(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + return errorType; + } + const getter = getDeclarationOfKind(symbol, SyntaxKind.GetAccessor); + const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor); + const accessor = tryCast(getDeclarationOfKind(symbol, SyntaxKind.PropertyDeclaration), isAutoAccessorPropertyDeclaration); + + // We try to resolve a getter type annotation, a setter type annotation, or a getter function + // body return type inference, in that order. + let type = getter && isInJSFile(getter) && getTypeForDeclarationFromJSDocComment(getter) || + getAnnotatedAccessorType(getter) || + getAnnotatedAccessorType(setter) || + getAnnotatedAccessorType(accessor) || + getter && getter.body && getReturnTypeFromBody(getter) || + accessor && accessor.initializer && getWidenedTypeForVariableLikeDeclaration(accessor, /*reportErrors*/ true); + if (!type) { + if (setter && !isPrivateWithinAmbient(setter)) { + errorOrSuggestion(noImplicitAny, setter, Diagnostics.Property_0_implicitly_has_type_any_because_its_set_accessor_lacks_a_parameter_type_annotation, symbolToString(symbol)); + } + else if (getter && !isPrivateWithinAmbient(getter)) { + errorOrSuggestion(noImplicitAny, getter, Diagnostics.Property_0_implicitly_has_type_any_because_its_get_accessor_lacks_a_return_type_annotation, symbolToString(symbol)); + } + else if (accessor && !isPrivateWithinAmbient(accessor)) { + errorOrSuggestion(noImplicitAny, accessor, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), "any"); + } + type = anyType; + } + if (!popTypeResolution()) { + if (getAnnotatedAccessorTypeNode(getter)) { + error(getter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + else if (getAnnotatedAccessorTypeNode(setter)) { + error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + else if (getAnnotatedAccessorTypeNode(accessor)) { + error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + else if (getter && noImplicitAny) { + error(getter, Diagnostics._0_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions, symbolToString(symbol)); + } + type = anyType; + } + links.type ??= type; + } + return links.type; + } + + function getWriteTypeOfAccessors(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.writeType) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.WriteType)) { + return errorType; + } + + const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor) + ?? tryCast(getDeclarationOfKind(symbol, SyntaxKind.PropertyDeclaration), isAutoAccessorPropertyDeclaration); + let writeType = getAnnotatedAccessorType(setter); + if (!popTypeResolution()) { + if (getAnnotatedAccessorTypeNode(setter)) { + error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + writeType = anyType; + } + // Absent an explicit setter type annotation we use the read type of the accessor. + links.writeType ??= writeType || getTypeOfAccessors(symbol); + } + return links.writeType; + } + + function getBaseTypeVariableOfClass(symbol: Symbol) { + const baseConstructorType = getBaseConstructorTypeOfClass(getDeclaredTypeOfClassOrInterface(symbol)); + return baseConstructorType.flags & TypeFlags.TypeVariable ? baseConstructorType : + baseConstructorType.flags & TypeFlags.Intersection ? find((baseConstructorType as IntersectionType).types, t => !!(t.flags & TypeFlags.TypeVariable)) : + undefined; + } + + function getTypeOfFuncClassEnumModule(symbol: Symbol): Type { + let links = getSymbolLinks(symbol); + const originalLinks = links; + if (!links.type) { + const expando = symbol.valueDeclaration && getSymbolOfExpando(symbol.valueDeclaration, /*allowDeclaration*/ false); + if (expando) { + const merged = mergeJSSymbols(symbol, expando); + if (merged) { + // note:we overwrite links because we just cloned the symbol + symbol = merged; + links = merged.links; + } + } + originalLinks.type = links.type = getTypeOfFuncClassEnumModuleWorker(symbol); + } + return links.type; + } + + function getTypeOfFuncClassEnumModuleWorker(symbol: Symbol): Type { + const declaration = symbol.valueDeclaration; + if (symbol.flags & SymbolFlags.Module && isShorthandAmbientModuleSymbol(symbol)) { + return anyType; + } + else if ( + declaration && (declaration.kind === SyntaxKind.BinaryExpression || + isAccessExpression(declaration) && + declaration.parent.kind === SyntaxKind.BinaryExpression) + ) { + return getWidenedTypeForAssignmentDeclaration(symbol); + } + else if (symbol.flags & SymbolFlags.ValueModule && declaration && isSourceFile(declaration) && declaration.commonJsModuleIndicator) { + const resolvedModule = resolveExternalModuleSymbol(symbol); + if (resolvedModule !== symbol) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + return errorType; + } + const exportEquals = getMergedSymbol(symbol.exports!.get(InternalSymbolName.ExportEquals)!); + const type = getWidenedTypeForAssignmentDeclaration(exportEquals, exportEquals === resolvedModule ? undefined : resolvedModule); + if (!popTypeResolution()) { + return reportCircularityError(symbol); + } + return type; + } + } + const type = createObjectType(ObjectFlags.Anonymous, symbol); + if (symbol.flags & SymbolFlags.Class) { + const baseTypeVariable = getBaseTypeVariableOfClass(symbol); + return baseTypeVariable ? getIntersectionType([type, baseTypeVariable]) : type; + } + else { + return strictNullChecks && symbol.flags & SymbolFlags.Optional ? getOptionalType(type, /*isProperty*/ true) : type; + } + } + + function getTypeOfEnumMember(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.type || (links.type = getDeclaredTypeOfEnumMember(symbol)); + } + + function getTypeOfAlias(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + return errorType; + } + const targetSymbol = resolveAlias(symbol); + const exportSymbol = symbol.declarations && getTargetOfAliasDeclaration(getDeclarationOfAliasSymbol(symbol)!, /*dontRecursivelyResolve*/ true); + const declaredType = firstDefined(exportSymbol?.declarations, d => isExportAssignment(d) ? tryGetTypeFromEffectiveTypeNode(d) : undefined); + + // It only makes sense to get the type of a value symbol. If the result of resolving + // the alias is not a value, then it has no type. To get the type associated with a + // type symbol, call getDeclaredTypeOfSymbol. + // This check is important because without it, a call to getTypeOfSymbol could end + // up recursively calling getTypeOfAlias, causing a stack overflow. + links.type ??= exportSymbol?.declarations && isDuplicatedCommonJSExport(exportSymbol.declarations) && symbol.declarations!.length ? getFlowTypeFromCommonJSExport(exportSymbol) + : isDuplicatedCommonJSExport(symbol.declarations) ? autoType + : declaredType ? declaredType + : getSymbolFlags(targetSymbol) & SymbolFlags.Value ? getTypeOfSymbol(targetSymbol) + : errorType; + + if (!popTypeResolution()) { + reportCircularityError(exportSymbol ?? symbol); + return links.type ??= errorType; + } + } + return links.type; + } + + function getTypeOfInstantiatedSymbol(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.type || (links.type = instantiateType(getTypeOfSymbol(links.target!), links.mapper)); + } + + function getWriteTypeOfInstantiatedSymbol(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.writeType || (links.writeType = instantiateType(getWriteTypeOfSymbol(links.target!), links.mapper)); + } + + function reportCircularityError(symbol: Symbol) { + const declaration = symbol.valueDeclaration; + // Check if variable has type annotation that circularly references the variable itself + if (declaration) { + if (getEffectiveTypeAnnotationNode(declaration)) { + error(symbol.valueDeclaration, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + return errorType; + } + // Check if variable has initializer that circularly references the variable itself + if (noImplicitAny && (declaration.kind !== SyntaxKind.Parameter || (declaration as HasInitializer).initializer)) { + error(symbol.valueDeclaration, Diagnostics._0_implicitly_has_type_any_because_it_does_not_have_a_type_annotation_and_is_referenced_directly_or_indirectly_in_its_own_initializer, symbolToString(symbol)); + } + } + else if (symbol.flags & SymbolFlags.Alias) { + const node = getDeclarationOfAliasSymbol(symbol); + if (node) { + error(node, Diagnostics.Circular_definition_of_import_alias_0, symbolToString(symbol)); + } + } + // Circularities could also result from parameters in function expressions that end up + // having themselves as contextual types following type argument inference. In those cases + // we have already reported an implicit any error so we don't report anything here. + return anyType; + } + + function getTypeOfSymbolWithDeferredType(symbol: Symbol) { + const links = getSymbolLinks(symbol); + if (!links.type) { + Debug.assertIsDefined(links.deferralParent); + Debug.assertIsDefined(links.deferralConstituents); + links.type = links.deferralParent.flags & TypeFlags.Union ? getUnionType(links.deferralConstituents) : getIntersectionType(links.deferralConstituents); + } + return links.type; + } + + function getWriteTypeOfSymbolWithDeferredType(symbol: Symbol): Type | undefined { + const links = getSymbolLinks(symbol); + if (!links.writeType && links.deferralWriteConstituents) { + Debug.assertIsDefined(links.deferralParent); + Debug.assertIsDefined(links.deferralConstituents); + links.writeType = links.deferralParent.flags & TypeFlags.Union ? getUnionType(links.deferralWriteConstituents) : getIntersectionType(links.deferralWriteConstituents); + } + return links.writeType; + } + + /** + * Distinct write types come only from set accessors, but synthetic union and intersection + * properties deriving from set accessors will either pre-compute or defer the union or + * intersection of the writeTypes of their constituents. + */ + function getWriteTypeOfSymbol(symbol: Symbol): Type { + const checkFlags = getCheckFlags(symbol); + if (symbol.flags & SymbolFlags.Property) { + return checkFlags & CheckFlags.SyntheticProperty ? + checkFlags & CheckFlags.DeferredType ? + getWriteTypeOfSymbolWithDeferredType(symbol) || getTypeOfSymbolWithDeferredType(symbol) : + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.SyntheticProperty + (symbol as TransientSymbol).links.writeType || (symbol as TransientSymbol).links.type! : + removeMissingType(getTypeOfSymbol(symbol), !!(symbol.flags & SymbolFlags.Optional)); + } + if (symbol.flags & SymbolFlags.Accessor) { + return checkFlags & CheckFlags.Instantiated ? + getWriteTypeOfInstantiatedSymbol(symbol) : + getWriteTypeOfAccessors(symbol); + } + return getTypeOfSymbol(symbol); + } + + function getTypeOfSymbol(symbol: Symbol, checkMode?: CheckMode): Type { + const checkFlags = getCheckFlags(symbol); + if (checkFlags & CheckFlags.DeferredType) { + return getTypeOfSymbolWithDeferredType(symbol); + } + if (checkFlags & CheckFlags.Instantiated) { + return getTypeOfInstantiatedSymbol(symbol); + } + if (checkFlags & CheckFlags.Mapped) { + return getTypeOfMappedSymbol(symbol as MappedSymbol); + } + if (checkFlags & CheckFlags.ReverseMapped) { + return getTypeOfReverseMappedSymbol(symbol as ReverseMappedSymbol); + } + if (symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property)) { + return getTypeOfVariableOrParameterOrProperty(symbol, checkMode); + } + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.Enum | SymbolFlags.ValueModule)) { + return getTypeOfFuncClassEnumModule(symbol); + } + if (symbol.flags & SymbolFlags.EnumMember) { + return getTypeOfEnumMember(symbol); + } + if (symbol.flags & SymbolFlags.Accessor) { + return getTypeOfAccessors(symbol); + } + if (symbol.flags & SymbolFlags.Alias) { + return getTypeOfAlias(symbol); + } + return errorType; + } + + function getNonMissingTypeOfSymbol(symbol: Symbol) { + return removeMissingType(getTypeOfSymbol(symbol), !!(symbol.flags & SymbolFlags.Optional)); + } + + function isReferenceToType(type: Type, target: Type) { + return type !== undefined + && target !== undefined + && (getObjectFlags(type) & ObjectFlags.Reference) !== 0 + && (type as TypeReference).target === target; + } + + function getTargetType(type: Type): Type { + return getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).target : type; + } + + // TODO: GH#18217 If `checkBase` is undefined, we should not call this because this will always return false. + function hasBaseType(type: Type, checkBase: Type | undefined) { + return check(type); + function check(type: Type): boolean { + if (getObjectFlags(type) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference)) { + const target = getTargetType(type) as InterfaceType; + return target === checkBase || some(getBaseTypes(target), check); + } + else if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, check); + } + return false; + } + } + + // Appends the type parameters given by a list of declarations to a set of type parameters and returns the resulting set. + // The function allocates a new array if the input type parameter set is undefined, but otherwise it modifies the set + // in-place and returns the same array. + function appendTypeParameters(typeParameters: TypeParameter[] | undefined, declarations: readonly TypeParameterDeclaration[]): TypeParameter[] | undefined { + for (const declaration of declarations) { + typeParameters = appendIfUnique(typeParameters, getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(declaration))); + } + return typeParameters; + } + + // Return the outer type parameters of a node or undefined if the node has no outer type parameters. + function getOuterTypeParameters(node: Node, includeThisTypes?: boolean): TypeParameter[] | undefined { + while (true) { + node = node.parent; // TODO: GH#18217 Use SourceFile kind check instead + if (node && isBinaryExpression(node)) { + // prototype assignments get the outer type parameters of their constructor function + const assignmentKind = getAssignmentDeclarationKind(node); + if (assignmentKind === AssignmentDeclarationKind.Prototype || assignmentKind === AssignmentDeclarationKind.PrototypeProperty) { + const symbol = getSymbolOfDeclaration(node.left as BindableStaticNameExpression | PropertyAssignment); + if (symbol && symbol.parent && !findAncestor(symbol.parent.valueDeclaration, d => node === d)) { + node = symbol.parent.valueDeclaration!; + } + } + } + if (!node) { + return undefined; + } + switch (node.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.CallSignature: + case SyntaxKind.ConstructSignature: + case SyntaxKind.MethodSignature: + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.JSDocFunctionType: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.JSDocTemplateTag: + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocEnumTag: + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.MappedType: + case SyntaxKind.ConditionalType: { + const outerTypeParameters = getOuterTypeParameters(node, includeThisTypes); + if (node.kind === SyntaxKind.MappedType) { + return append(outerTypeParameters, getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration((node as MappedTypeNode).typeParameter))); + } + else if (node.kind === SyntaxKind.ConditionalType) { + return concatenate(outerTypeParameters, getInferTypeParameters(node as ConditionalTypeNode)); + } + const outerAndOwnTypeParameters = appendTypeParameters(outerTypeParameters, getEffectiveTypeParameterDeclarations(node as DeclarationWithTypeParameters)); + const thisType = includeThisTypes && + (node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression || node.kind === SyntaxKind.InterfaceDeclaration || isJSConstructor(node)) && + getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node as ClassLikeDeclaration | InterfaceDeclaration)).thisType; + return thisType ? append(outerAndOwnTypeParameters, thisType) : outerAndOwnTypeParameters; + } + case SyntaxKind.JSDocParameterTag: + const paramSymbol = getParameterSymbolFromJSDoc(node as JSDocParameterTag); + if (paramSymbol) { + node = paramSymbol.valueDeclaration!; + } + break; + case SyntaxKind.JSDoc: { + const outerTypeParameters = getOuterTypeParameters(node, includeThisTypes); + return (node as JSDoc).tags + ? appendTypeParameters(outerTypeParameters, flatMap((node as JSDoc).tags, t => isJSDocTemplateTag(t) ? t.typeParameters : undefined)) + : outerTypeParameters; + } + } + } + } + + // The outer type parameters are those defined by enclosing generic classes, methods, or functions. + function getOuterTypeParametersOfClassOrInterface(symbol: Symbol): TypeParameter[] | undefined { + const declaration = (symbol.flags & SymbolFlags.Class || symbol.flags & SymbolFlags.Function) + ? symbol.valueDeclaration + : symbol.declarations?.find(decl => { + if (decl.kind === SyntaxKind.InterfaceDeclaration) { + return true; + } + if (decl.kind !== SyntaxKind.VariableDeclaration) { + return false; + } + const initializer = (decl as VariableDeclaration).initializer; + return !!initializer && (initializer.kind === SyntaxKind.FunctionExpression || initializer.kind === SyntaxKind.ArrowFunction); + })!; + Debug.assert(!!declaration, "Class was missing valueDeclaration -OR- non-class had no interface declarations"); + return getOuterTypeParameters(declaration); + } + + // The local type parameters are the combined set of type parameters from all declarations of the class, + // interface, or type alias. + function getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol: Symbol): TypeParameter[] | undefined { + if (!symbol.declarations) { + return; + } + let result: TypeParameter[] | undefined; + for (const node of symbol.declarations) { + if ( + node.kind === SyntaxKind.InterfaceDeclaration || + node.kind === SyntaxKind.ClassDeclaration || + node.kind === SyntaxKind.ClassExpression || + isJSConstructor(node) || + isTypeAlias(node) + ) { + const declaration = node as InterfaceDeclaration | TypeAliasDeclaration | JSDocTypedefTag | JSDocCallbackTag; + result = appendTypeParameters(result, getEffectiveTypeParameterDeclarations(declaration)); + } + } + return result; + } + + // The full set of type parameters for a generic class or interface type consists of its outer type parameters plus + // its locally declared type parameters. + function getTypeParametersOfClassOrInterface(symbol: Symbol): TypeParameter[] | undefined { + return concatenate(getOuterTypeParametersOfClassOrInterface(symbol), getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol)); + } + + // A type is a mixin constructor if it has a single construct signature taking no type parameters and a single + // rest parameter of type any[]. + function isMixinConstructorType(type: Type) { + const signatures = getSignaturesOfType(type, SignatureKind.Construct); + if (signatures.length === 1) { + const s = signatures[0]; + if (!s.typeParameters && s.parameters.length === 1 && signatureHasRestParameter(s)) { + const paramType = getTypeOfParameter(s.parameters[0]); + return isTypeAny(paramType) || getElementTypeOfArrayType(paramType) === anyType; + } + } + return false; + } + + function isConstructorType(type: Type): boolean { + if (getSignaturesOfType(type, SignatureKind.Construct).length > 0) { + return true; + } + if (type.flags & TypeFlags.TypeVariable) { + const constraint = getBaseConstraintOfType(type); + return !!constraint && isMixinConstructorType(constraint); + } + return false; + } + + function getBaseTypeNodeOfClass(type: InterfaceType): ExpressionWithTypeArguments | undefined { + const decl = getClassLikeDeclarationOfSymbol(type.symbol); + return decl && getEffectiveBaseTypeNode(decl); + } + + function getConstructorsForTypeArguments(type: Type, typeArgumentNodes: readonly TypeNode[] | undefined, location: Node): readonly Signature[] { + const typeArgCount = length(typeArgumentNodes); + const isJavascript = isInJSFile(location); + return filter(getSignaturesOfType(type, SignatureKind.Construct), sig => (isJavascript || typeArgCount >= getMinTypeArgumentCount(sig.typeParameters)) && typeArgCount <= length(sig.typeParameters)); + } + + function getInstantiatedConstructorsForTypeArguments(type: Type, typeArgumentNodes: readonly TypeNode[] | undefined, location: Node): readonly Signature[] { + const signatures = getConstructorsForTypeArguments(type, typeArgumentNodes, location); + const typeArguments = map(typeArgumentNodes, getTypeFromTypeNode); + return sameMap(signatures, sig => some(sig.typeParameters) ? getSignatureInstantiation(sig, typeArguments, isInJSFile(location)) : sig); + } + + /** + * The base constructor of a class can resolve to + * * undefinedType if the class has no extends clause, + * * errorType if an error occurred during resolution of the extends expression, + * * nullType if the extends expression is the null value, + * * anyType if the extends expression has type any, or + * * an object type with at least one construct signature. + */ + function getBaseConstructorTypeOfClass(type: InterfaceType): Type { + if (!type.resolvedBaseConstructorType) { + const decl = getClassLikeDeclarationOfSymbol(type.symbol); + const extended = decl && getEffectiveBaseTypeNode(decl); + const baseTypeNode = getBaseTypeNodeOfClass(type); + if (!baseTypeNode) { + return type.resolvedBaseConstructorType = undefinedType; + } + if (!pushTypeResolution(type, TypeSystemPropertyName.ResolvedBaseConstructorType)) { + return errorType; + } + const baseConstructorType = checkExpression(baseTypeNode.expression); + if (extended && baseTypeNode !== extended) { + Debug.assert(!extended.typeArguments); // Because this is in a JS file, and baseTypeNode is in an @extends tag + checkExpression(extended.expression); + } + if (baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection)) { + // Resolving the members of a class requires us to resolve the base class of that class. + // We force resolution here such that we catch circularities now. + resolveStructuredTypeMembers(baseConstructorType as ObjectType); + } + if (!popTypeResolution()) { + error(type.symbol.valueDeclaration, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_base_expression, symbolToString(type.symbol)); + return type.resolvedBaseConstructorType ??= errorType; + } + if (!(baseConstructorType.flags & TypeFlags.Any) && baseConstructorType !== nullWideningType && !isConstructorType(baseConstructorType)) { + const err = error(baseTypeNode.expression, Diagnostics.Type_0_is_not_a_constructor_function_type, typeToString(baseConstructorType)); + if (baseConstructorType.flags & TypeFlags.TypeParameter) { + const constraint = getConstraintFromTypeParameter(baseConstructorType); + let ctorReturn: Type = unknownType; + if (constraint) { + const ctorSig = getSignaturesOfType(constraint, SignatureKind.Construct); + if (ctorSig[0]) { + ctorReturn = getReturnTypeOfSignature(ctorSig[0]); + } + } + if (baseConstructorType.symbol.declarations) { + addRelatedInfo(err, createDiagnosticForNode(baseConstructorType.symbol.declarations[0], Diagnostics.Did_you_mean_for_0_to_be_constrained_to_type_new_args_Colon_any_1, symbolToString(baseConstructorType.symbol), typeToString(ctorReturn))); + } + } + return type.resolvedBaseConstructorType ??= errorType; + } + type.resolvedBaseConstructorType ??= baseConstructorType; + } + return type.resolvedBaseConstructorType; + } + + function getImplementsTypes(type: InterfaceType): BaseType[] { + let resolvedImplementsTypes: BaseType[] = emptyArray; + if (type.symbol.declarations) { + for (const declaration of type.symbol.declarations) { + const implementsTypeNodes = getEffectiveImplementsTypeNodes(declaration as ClassLikeDeclaration); + if (!implementsTypeNodes) continue; + for (const node of implementsTypeNodes) { + const implementsType = getTypeFromTypeNode(node); + if (!isErrorType(implementsType)) { + if (resolvedImplementsTypes === emptyArray) { + resolvedImplementsTypes = [implementsType as ObjectType]; + } + else { + resolvedImplementsTypes.push(implementsType); + } + } + } + } + } + return resolvedImplementsTypes; + } + + function reportCircularBaseType(node: Node, type: Type) { + error(node, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType)); + } + + function getBaseTypes(type: InterfaceType): BaseType[] { + if (!type.baseTypesResolved) { + if (pushTypeResolution(type, TypeSystemPropertyName.ResolvedBaseTypes)) { + if (type.objectFlags & ObjectFlags.Tuple) { + type.resolvedBaseTypes = [getTupleBaseType(type as TupleType)]; + } + else if (type.symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { + if (type.symbol.flags & SymbolFlags.Class) { + resolveBaseTypesOfClass(type); + } + if (type.symbol.flags & SymbolFlags.Interface) { + resolveBaseTypesOfInterface(type); + } + } + else { + Debug.fail("type must be class or interface"); + } + if (!popTypeResolution() && type.symbol.declarations) { + for (const declaration of type.symbol.declarations) { + if (declaration.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.InterfaceDeclaration) { + reportCircularBaseType(declaration, type); + } + } + } + } + type.baseTypesResolved = true; + } + return type.resolvedBaseTypes; + } + + function getTupleBaseType(type: TupleType) { + const elementTypes = sameMap(type.typeParameters, (t, i) => type.elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t); + return createArrayType(getUnionType(elementTypes || emptyArray), type.readonly); + } + + function resolveBaseTypesOfClass(type: InterfaceType) { + type.resolvedBaseTypes = resolvingEmptyArray; + const baseConstructorType = getApparentType(getBaseConstructorTypeOfClass(type)); + if (!(baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Any))) { + return type.resolvedBaseTypes = emptyArray; + } + const baseTypeNode = getBaseTypeNodeOfClass(type)!; + let baseType: Type; + const originalBaseType = baseConstructorType.symbol ? getDeclaredTypeOfSymbol(baseConstructorType.symbol) : undefined; + if ( + baseConstructorType.symbol && baseConstructorType.symbol.flags & SymbolFlags.Class && + areAllOuterTypeParametersApplied(originalBaseType!) + ) { + // When base constructor type is a class with no captured type arguments we know that the constructors all have the same type parameters as the + // class and all return the instance type of the class. There is no need for further checks and we can apply the + // type arguments in the same manner as a type reference to get the same error reporting experience. + baseType = getTypeFromClassOrInterfaceReference(baseTypeNode, baseConstructorType.symbol); + } + else if (baseConstructorType.flags & TypeFlags.Any) { + baseType = baseConstructorType; + } + else { + // The class derives from a "class-like" constructor function, check that we have at least one construct signature + // with a matching number of type parameters and use the return type of the first instantiated signature. Elsewhere + // we check that all instantiated signatures return the same type. + const constructors = getInstantiatedConstructorsForTypeArguments(baseConstructorType, baseTypeNode.typeArguments, baseTypeNode); + if (!constructors.length) { + error(baseTypeNode.expression, Diagnostics.No_base_constructor_has_the_specified_number_of_type_arguments); + return type.resolvedBaseTypes = emptyArray; + } + baseType = getReturnTypeOfSignature(constructors[0]); + } + + if (isErrorType(baseType)) { + return type.resolvedBaseTypes = emptyArray; + } + const reducedBaseType = getReducedType(baseType); + if (!isValidBaseType(reducedBaseType)) { + const elaboration = elaborateNeverIntersection(/*errorInfo*/ undefined, baseType); + const diagnostic = chainDiagnosticMessages(elaboration, Diagnostics.Base_constructor_return_type_0_is_not_an_object_type_or_intersection_of_object_types_with_statically_known_members, typeToString(reducedBaseType)); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(baseTypeNode.expression), baseTypeNode.expression, diagnostic)); + return type.resolvedBaseTypes = emptyArray; + } + if (type === reducedBaseType || hasBaseType(reducedBaseType, type)) { + error(type.symbol.valueDeclaration, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType)); + return type.resolvedBaseTypes = emptyArray; + } + if (type.resolvedBaseTypes === resolvingEmptyArray) { + // Circular reference, likely through instantiation of default parameters + // (otherwise there'd be an error from hasBaseType) - this is fine, but `.members` should be reset + // as `getIndexedAccessType` via `instantiateType` via `getTypeFromClassOrInterfaceReference` forces a + // partial instantiation of the members without the base types fully resolved + type.members = undefined; + } + return type.resolvedBaseTypes = [reducedBaseType]; + } + + function areAllOuterTypeParametersApplied(type: Type): boolean { // TODO: GH#18217 Shouldn't this take an InterfaceType? + // An unapplied type parameter has its symbol still the same as the matching argument symbol. + // Since parameters are applied outer-to-inner, only the last outer parameter needs to be checked. + const outerTypeParameters = (type as InterfaceType).outerTypeParameters; + if (outerTypeParameters) { + const last = outerTypeParameters.length - 1; + const typeArguments = getTypeArguments(type as TypeReference); + return outerTypeParameters[last].symbol !== typeArguments[last].symbol; + } + return true; + } + + // A valid base type is `any`, an object type or intersection of object types. + function isValidBaseType(type: Type): type is BaseType { + if (type.flags & TypeFlags.TypeParameter) { + const constraint = getBaseConstraintOfType(type); + if (constraint) { + return isValidBaseType(constraint); + } + } + // TODO: Given that we allow type parmeters here now, is this `!isGenericMappedType(type)` check really needed? + // There's no reason a `T` should be allowed while a `Readonly` should not. + return !!(type.flags & (TypeFlags.Object | TypeFlags.NonPrimitive | TypeFlags.Any) && !isGenericMappedType(type) || + type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, isValidBaseType)); + } + + function resolveBaseTypesOfInterface(type: InterfaceType): void { + type.resolvedBaseTypes = type.resolvedBaseTypes || emptyArray; + if (type.symbol.declarations) { + for (const declaration of type.symbol.declarations) { + if (declaration.kind === SyntaxKind.InterfaceDeclaration && getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration)) { + for (const node of getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration)!) { + const baseType = getReducedType(getTypeFromTypeNode(node)); + if (!isErrorType(baseType)) { + if (isValidBaseType(baseType)) { + if (type !== baseType && !hasBaseType(baseType, type)) { + if (type.resolvedBaseTypes === emptyArray) { + type.resolvedBaseTypes = [baseType as ObjectType]; + } + else { + type.resolvedBaseTypes.push(baseType); + } + } + else { + reportCircularBaseType(declaration, type); + } + } + else { + error(node, Diagnostics.An_interface_can_only_extend_an_object_type_or_intersection_of_object_types_with_statically_known_members); + } + } + } + } + } + } + } + + /** + * Returns true if the interface given by the symbol is free of "this" references. + * + * Specifically, the result is true if the interface itself contains no references + * to "this" in its body, if all base types are interfaces, + * and if none of the base interfaces have a "this" type. + */ + function isThislessInterface(symbol: Symbol): boolean { + if (!symbol.declarations) { + return true; + } + for (const declaration of symbol.declarations) { + if (declaration.kind === SyntaxKind.InterfaceDeclaration) { + if (declaration.flags & NodeFlags.ContainsThis) { + return false; + } + const baseTypeNodes = getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration); + if (baseTypeNodes) { + for (const node of baseTypeNodes) { + if (isEntityNameExpression(node.expression)) { + const baseSymbol = resolveEntityName(node.expression, SymbolFlags.Type, /*ignoreErrors*/ true); + if (!baseSymbol || !(baseSymbol.flags & SymbolFlags.Interface) || getDeclaredTypeOfClassOrInterface(baseSymbol).thisType) { + return false; + } + } + } + } + } + } + return true; + } + + function getDeclaredTypeOfClassOrInterface(symbol: Symbol): InterfaceType { + let links = getSymbolLinks(symbol); + const originalLinks = links; + if (!links.declaredType) { + const kind = symbol.flags & SymbolFlags.Class ? ObjectFlags.Class : ObjectFlags.Interface; + const merged = mergeJSSymbols(symbol, symbol.valueDeclaration && getAssignedClassSymbol(symbol.valueDeclaration)); + if (merged) { + // note:we overwrite links because we just cloned the symbol + symbol = merged; + links = merged.links; + } + + const type = originalLinks.declaredType = links.declaredType = createObjectType(kind, symbol) as InterfaceType; + const outerTypeParameters = getOuterTypeParametersOfClassOrInterface(symbol); + const localTypeParameters = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + // A class or interface is generic if it has type parameters or a "this" type. We always give classes a "this" type + // because it is not feasible to analyze all members to determine if the "this" type escapes the class (in particular, + // property types inferred from initializers and method return types inferred from return statements are very hard + // to exhaustively analyze). We give interfaces a "this" type if we can't definitely determine that they are free of + // "this" references. + if (outerTypeParameters || localTypeParameters || kind === ObjectFlags.Class || !isThislessInterface(symbol)) { + type.objectFlags |= ObjectFlags.Reference; + type.typeParameters = concatenate(outerTypeParameters, localTypeParameters); + type.outerTypeParameters = outerTypeParameters; + type.localTypeParameters = localTypeParameters; + (type as GenericType).instantiations = new Map(); + (type as GenericType).instantiations.set(getTypeListId(type.typeParameters), type as GenericType); + (type as GenericType).target = type as GenericType; + (type as GenericType).resolvedTypeArguments = type.typeParameters; + type.thisType = createTypeParameter(symbol); + type.thisType.isThisType = true; + type.thisType.constraint = type; + } + } + return links.declaredType as InterfaceType; + } + + function getDeclaredTypeOfTypeAlias(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.declaredType) { + // Note that we use the links object as the target here because the symbol object is used as the unique + // identity for resolution of the 'type' property in SymbolLinks. + if (!pushTypeResolution(symbol, TypeSystemPropertyName.DeclaredType)) { + return errorType; + } + + const declaration = Debug.checkDefined(symbol.declarations?.find(isTypeAlias), "Type alias symbol with no valid declaration found"); + const typeNode = isJSDocTypeAlias(declaration) ? declaration.typeExpression : declaration.type; + // If typeNode is missing, we will error in checkJSDocTypedefTag. + let type = typeNode ? getTypeFromTypeNode(typeNode) : errorType; + + if (popTypeResolution()) { + const typeParameters = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + if (typeParameters) { + // Initialize the instantiation cache for generic type aliases. The declared type corresponds to + // an instantiation of the type alias with the type parameters supplied as type arguments. + links.typeParameters = typeParameters; + links.instantiations = new Map(); + links.instantiations.set(getTypeListId(typeParameters), type); + } + } + else { + type = errorType; + if (declaration.kind === SyntaxKind.JSDocEnumTag) { + error(declaration.typeExpression.type, Diagnostics.Type_alias_0_circularly_references_itself, symbolToString(symbol)); + } + else { + error(isNamedDeclaration(declaration) ? declaration.name || declaration : declaration, Diagnostics.Type_alias_0_circularly_references_itself, symbolToString(symbol)); + } + } + links.declaredType ??= type; + } + return links.declaredType; + } + + function getBaseTypeOfEnumLikeType(type: Type) { + return type.flags & TypeFlags.EnumLike && type.symbol.flags & SymbolFlags.EnumMember ? getDeclaredTypeOfSymbol(getParentOfSymbol(type.symbol)!) : type; + } + + function getDeclaredTypeOfEnum(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.declaredType) { + const memberTypeList: Type[] = []; + if (symbol.declarations) { + for (const declaration of symbol.declarations) { + if (declaration.kind === SyntaxKind.EnumDeclaration) { + for (const member of (declaration as EnumDeclaration).members) { + if (hasBindableName(member)) { + const memberSymbol = getSymbolOfDeclaration(member); + const value = getEnumMemberValue(member).value; + const memberType = getFreshTypeOfLiteralType( + value !== undefined ? + getEnumLiteralType(value, getSymbolId(symbol), memberSymbol) : + createComputedEnumType(memberSymbol), + ); + getSymbolLinks(memberSymbol).declaredType = memberType; + memberTypeList.push(getRegularTypeOfLiteralType(memberType)); + } + } + } + } + } + const enumType = memberTypeList.length ? + getUnionType(memberTypeList, UnionReduction.Literal, symbol, /*aliasTypeArguments*/ undefined) : + createComputedEnumType(symbol); + if (enumType.flags & TypeFlags.Union) { + enumType.flags |= TypeFlags.EnumLiteral; + enumType.symbol = symbol; + } + links.declaredType = enumType; + } + return links.declaredType; + } + + function createComputedEnumType(symbol: Symbol) { + const regularType = createTypeWithSymbol(TypeFlags.Enum, symbol) as EnumType; + const freshType = createTypeWithSymbol(TypeFlags.Enum, symbol) as EnumType; + regularType.regularType = regularType; + regularType.freshType = freshType; + freshType.regularType = regularType; + freshType.freshType = freshType; + return regularType; + } + + function getDeclaredTypeOfEnumMember(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.declaredType) { + const enumType = getDeclaredTypeOfEnum(getParentOfSymbol(symbol)!); + if (!links.declaredType) { + links.declaredType = enumType; + } + } + return links.declaredType; + } + + function getDeclaredTypeOfTypeParameter(symbol: Symbol): TypeParameter { + const links = getSymbolLinks(symbol); + return links.declaredType || (links.declaredType = createTypeParameter(symbol)); + } + + function getDeclaredTypeOfAlias(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.declaredType || (links.declaredType = getDeclaredTypeOfSymbol(resolveAlias(symbol))); + } + + function getDeclaredTypeOfSymbol(symbol: Symbol): Type { + return tryGetDeclaredTypeOfSymbol(symbol) || errorType; + } + + function tryGetDeclaredTypeOfSymbol(symbol: Symbol): Type | undefined { + if (symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { + return getDeclaredTypeOfClassOrInterface(symbol); + } + if (symbol.flags & SymbolFlags.TypeAlias) { + return getDeclaredTypeOfTypeAlias(symbol); + } + if (symbol.flags & SymbolFlags.TypeParameter) { + return getDeclaredTypeOfTypeParameter(symbol); + } + if (symbol.flags & SymbolFlags.Enum) { + return getDeclaredTypeOfEnum(symbol); + } + if (symbol.flags & SymbolFlags.EnumMember) { + return getDeclaredTypeOfEnumMember(symbol); + } + if (symbol.flags & SymbolFlags.Alias) { + return getDeclaredTypeOfAlias(symbol); + } + return undefined; + } + + /** + * A type is free of this references if it's the any, string, number, boolean, symbol, or void keyword, a string + * literal type, an array with an element type that is free of this references, or a type reference that is + * free of this references. + */ + function isThislessType(node: TypeNode): boolean { + switch (node.kind) { + case SyntaxKind.AnyKeyword: + case SyntaxKind.UnknownKeyword: + case SyntaxKind.StringKeyword: + case SyntaxKind.NumberKeyword: + case SyntaxKind.BigIntKeyword: + case SyntaxKind.BooleanKeyword: + case SyntaxKind.SymbolKeyword: + case SyntaxKind.ObjectKeyword: + case SyntaxKind.VoidKeyword: + case SyntaxKind.UndefinedKeyword: + case SyntaxKind.NeverKeyword: + case SyntaxKind.LiteralType: + return true; + case SyntaxKind.ArrayType: + return isThislessType((node as ArrayTypeNode).elementType); + case SyntaxKind.TypeReference: + return !(node as TypeReferenceNode).typeArguments || (node as TypeReferenceNode).typeArguments!.every(isThislessType); + } + return false; + } + + /** A type parameter is thisless if its constraint is thisless, or if it has no constraint. */ + function isThislessTypeParameter(node: TypeParameterDeclaration) { + const constraint = getEffectiveConstraintOfTypeParameter(node); + return !constraint || isThislessType(constraint); + } + + /** + * A variable-like declaration is free of this references if it has a type annotation + * that is thisless, or if it has no type annotation and no initializer (and is thus of type any). + */ + function isThislessVariableLikeDeclaration(node: VariableLikeDeclaration): boolean { + const typeNode = getEffectiveTypeAnnotationNode(node); + return typeNode ? isThislessType(typeNode) : !hasInitializer(node); + } + + /** + * A function-like declaration is considered free of `this` references if it has a return type + * annotation that is free of this references and if each parameter is thisless and if + * each type parameter (if present) is thisless. + */ + function isThislessFunctionLikeDeclaration(node: FunctionLikeDeclaration): boolean { + const returnType = getEffectiveReturnTypeNode(node); + const typeParameters = getEffectiveTypeParameterDeclarations(node); + return (node.kind === SyntaxKind.Constructor || (!!returnType && isThislessType(returnType))) && + node.parameters.every(isThislessVariableLikeDeclaration) && + typeParameters.every(isThislessTypeParameter); + } + + /** + * Returns true if the class or interface member given by the symbol is free of "this" references. The + * function may return false for symbols that are actually free of "this" references because it is not + * feasible to perform a complete analysis in all cases. In particular, property members with types + * inferred from their initializers and function members with inferred return types are conservatively + * assumed not to be free of "this" references. + */ + function isThisless(symbol: Symbol): boolean { + if (symbol.declarations && symbol.declarations.length === 1) { + const declaration = symbol.declarations[0]; + if (declaration) { + switch (declaration.kind) { + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + return isThislessVariableLikeDeclaration(declaration as VariableLikeDeclaration); + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + case SyntaxKind.Constructor: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return isThislessFunctionLikeDeclaration(declaration as FunctionLikeDeclaration | AccessorDeclaration); + } + } + } + return false; + } + + // The mappingThisOnly flag indicates that the only type parameter being mapped is "this". When the flag is true, + // we check symbols to see if we can quickly conclude they are free of "this" references, thus needing no instantiation. + function createInstantiatedSymbolTable(symbols: Symbol[], mapper: TypeMapper, mappingThisOnly: boolean): SymbolTable { + const result = createSymbolTable(); + for (const symbol of symbols) { + result.set(symbol.escapedName, mappingThisOnly && isThisless(symbol) ? symbol : instantiateSymbol(symbol, mapper)); + } + return result; + } + + function addInheritedMembers(symbols: SymbolTable, baseSymbols: Symbol[]) { + for (const base of baseSymbols) { + if (isStaticPrivateIdentifierProperty(base)) { + continue; + } + const derived = symbols.get(base.escapedName); + if ( + !derived + // non-constructor/static-block assignment declarations are ignored here; they're not treated as overrides + || derived.valueDeclaration + && isBinaryExpression(derived.valueDeclaration) + && !isConstructorDeclaredProperty(derived) + && !getContainingClassStaticBlock(derived.valueDeclaration) + ) { + symbols.set(base.escapedName, base); + symbols.set(base.escapedName, base); + } + } + } + + function isStaticPrivateIdentifierProperty(s: Symbol): boolean { + return !!s.valueDeclaration && isPrivateIdentifierClassElementDeclaration(s.valueDeclaration) && isStatic(s.valueDeclaration); + } + + function resolveDeclaredMembers(type: InterfaceType): InterfaceTypeWithDeclaredMembers { + if (!(type as InterfaceTypeWithDeclaredMembers).declaredProperties) { + const symbol = type.symbol; + const members = getMembersOfSymbol(symbol); + (type as InterfaceTypeWithDeclaredMembers).declaredProperties = getNamedMembers(members); + // Start with signatures at empty array in case of recursive types + (type as InterfaceTypeWithDeclaredMembers).declaredCallSignatures = emptyArray; + (type as InterfaceTypeWithDeclaredMembers).declaredConstructSignatures = emptyArray; + (type as InterfaceTypeWithDeclaredMembers).declaredIndexInfos = emptyArray; + + (type as InterfaceTypeWithDeclaredMembers).declaredCallSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.Call)); + (type as InterfaceTypeWithDeclaredMembers).declaredConstructSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.New)); + (type as InterfaceTypeWithDeclaredMembers).declaredIndexInfos = getIndexInfosOfSymbol(symbol); + } + return type as InterfaceTypeWithDeclaredMembers; + } + + /** + * Indicates whether a declaration name is definitely late-bindable. + * A declaration name is only late-bindable if: + * - It is a `ComputedPropertyName`. + * - Its expression is an `Identifier` or either a `PropertyAccessExpression` an + * `ElementAccessExpression` consisting only of these same three types of nodes. + * - The type of its expression is a string or numeric literal type, or is a `unique symbol` type. + */ + function isLateBindableName(node: DeclarationName): node is LateBoundName { + if (!isComputedPropertyName(node) && !isElementAccessExpression(node)) { + return false; + } + const expr = isComputedPropertyName(node) ? node.expression : node.argumentExpression; + return isEntityNameExpression(expr) + && isTypeUsableAsPropertyName(isComputedPropertyName(node) ? checkComputedPropertyName(node) : checkExpressionCached(expr)); + } + + function isLateBoundName(name: __String): boolean { + return (name as string).charCodeAt(0) === CharacterCodes._ && + (name as string).charCodeAt(1) === CharacterCodes._ && + (name as string).charCodeAt(2) === CharacterCodes.at; + } + + /** + * Indicates whether a declaration has a late-bindable dynamic name. + */ + function hasLateBindableName(node: Declaration): node is LateBoundDeclaration | LateBoundBinaryExpressionDeclaration { + const name = getNameOfDeclaration(node); + return !!name && isLateBindableName(name); + } + + /** + * Indicates whether a declaration has an early-bound name or a dynamic name that can be late-bound. + */ + function hasBindableName(node: Declaration) { + return !hasDynamicName(node) || hasLateBindableName(node); + } + + /** + * Indicates whether a declaration name is a dynamic name that cannot be late-bound. + */ + function isNonBindableDynamicName(node: DeclarationName) { + return isDynamicName(node) && !isLateBindableName(node); + } + + /** + * Adds a declaration to a late-bound dynamic member. This performs the same function for + * late-bound members that `addDeclarationToSymbol` in binder.ts performs for early-bound + * members. + */ + function addDeclarationToLateBoundSymbol(symbol: Symbol, member: LateBoundDeclaration | BinaryExpression, symbolFlags: SymbolFlags) { + Debug.assert(!!(getCheckFlags(symbol) & CheckFlags.Late), "Expected a late-bound symbol."); + symbol.flags |= symbolFlags; + getSymbolLinks(member.symbol).lateSymbol = symbol; + if (!symbol.declarations) { + symbol.declarations = [member]; + } + else if (!member.symbol.isReplaceableByMethod) { + symbol.declarations.push(member); + } + if (symbolFlags & SymbolFlags.Value) { + if (!symbol.valueDeclaration || symbol.valueDeclaration.kind !== member.kind) { + symbol.valueDeclaration = member; + } + } + } + + /** + * Performs late-binding of a dynamic member. This performs the same function for + * late-bound members that `declareSymbol` in binder.ts performs for early-bound + * members. + * + * If a symbol is a dynamic name from a computed property, we perform an additional "late" + * binding phase to attempt to resolve the name for the symbol from the type of the computed + * property's expression. If the type of the expression is a string-literal, numeric-literal, + * or unique symbol type, we can use that type as the name of the symbol. + * + * For example, given: + * + * const x = Symbol(); + * + * interface I { + * [x]: number; + * } + * + * The binder gives the property `[x]: number` a special symbol with the name "__computed". + * In the late-binding phase we can type-check the expression `x` and see that it has a + * unique symbol type which we can then use as the name of the member. This allows users + * to define custom symbols that can be used in the members of an object type. + * + * @param parent The containing symbol for the member. + * @param earlySymbols The early-bound symbols of the parent. + * @param lateSymbols The late-bound symbols of the parent. + * @param decl The member to bind. + */ + function lateBindMember(parent: Symbol, earlySymbols: SymbolTable | undefined, lateSymbols: Map<__String, TransientSymbol>, decl: LateBoundDeclaration | LateBoundBinaryExpressionDeclaration) { + Debug.assert(!!decl.symbol, "The member is expected to have a symbol."); + const links = getNodeLinks(decl); + if (!links.resolvedSymbol) { + // In the event we attempt to resolve the late-bound name of this member recursively, + // fall back to the early-bound name of this member. + links.resolvedSymbol = decl.symbol; + const declName = isBinaryExpression(decl) ? decl.left : decl.name; + const type = isElementAccessExpression(declName) ? checkExpressionCached(declName.argumentExpression) : checkComputedPropertyName(declName); + if (isTypeUsableAsPropertyName(type)) { + const memberName = getPropertyNameFromType(type); + const symbolFlags = decl.symbol.flags; + + // Get or add a late-bound symbol for the member. This allows us to merge late-bound accessor declarations. + let lateSymbol = lateSymbols.get(memberName); + if (!lateSymbol) lateSymbols.set(memberName, lateSymbol = createSymbol(SymbolFlags.None, memberName, CheckFlags.Late)); + + // Report an error if there's a symbol declaration with the same name and conflicting flags. + const earlySymbol = earlySymbols && earlySymbols.get(memberName); + // Duplicate property declarations of classes are checked in checkClassForDuplicateDeclarations. + if (!(parent.flags & SymbolFlags.Class) && lateSymbol.flags & getExcludedSymbolFlags(symbolFlags)) { + // If we have an existing early-bound member, combine its declarations so that we can + // report an error at each declaration. + const declarations = earlySymbol ? concatenate(earlySymbol.declarations, lateSymbol.declarations) : lateSymbol.declarations; + const name = !(type.flags & TypeFlags.UniqueESSymbol) && unescapeLeadingUnderscores(memberName) || declarationNameToString(declName); + forEach(declarations, declaration => error(getNameOfDeclaration(declaration) || declaration, Diagnostics.Property_0_was_also_declared_here, name)); + error(declName || decl, Diagnostics.Duplicate_property_0, name); + lateSymbol = createSymbol(SymbolFlags.None, memberName, CheckFlags.Late); + } + lateSymbol.links.nameType = type; + addDeclarationToLateBoundSymbol(lateSymbol, decl, symbolFlags); + if (lateSymbol.parent) { + Debug.assert(lateSymbol.parent === parent, "Existing symbol parent should match new one"); + } + else { + lateSymbol.parent = parent; + } + return links.resolvedSymbol = lateSymbol; + } + } + return links.resolvedSymbol; + } + + function getResolvedMembersOrExportsOfSymbol(symbol: Symbol, resolutionKind: MembersOrExportsResolutionKind): Map<__String, Symbol> { + const links = getSymbolLinks(symbol); + if (!links[resolutionKind]) { + const isStatic = resolutionKind === MembersOrExportsResolutionKind.resolvedExports; + const earlySymbols = !isStatic ? symbol.members : + symbol.flags & SymbolFlags.Module ? getExportsOfModuleWorker(symbol).exports : + symbol.exports; + + // In the event we recursively resolve the members/exports of the symbol, we + // set the initial value of resolvedMembers/resolvedExports to the early-bound + // members/exports of the symbol. + links[resolutionKind] = earlySymbols || emptySymbols; + + // fill in any as-yet-unresolved late-bound members. + const lateSymbols = createSymbolTable() as Map<__String, TransientSymbol>; + for (const decl of symbol.declarations || emptyArray) { + const members = getMembersOfDeclaration(decl); + if (members) { + for (const member of members) { + if (isStatic === hasStaticModifier(member)) { + if (hasLateBindableName(member)) { + lateBindMember(symbol, earlySymbols, lateSymbols, member); + } + } + } + } + } + const assignments = getFunctionExpressionParentSymbolOrSymbol(symbol).assignmentDeclarationMembers; + + if (assignments) { + const decls = arrayFrom(assignments.values()); + for (const member of decls) { + const assignmentKind = getAssignmentDeclarationKind(member as BinaryExpression | CallExpression); + const isInstanceMember = assignmentKind === AssignmentDeclarationKind.PrototypeProperty + || isBinaryExpression(member) && isPossiblyAliasedThisProperty(member, assignmentKind) + || assignmentKind === AssignmentDeclarationKind.ObjectDefinePrototypeProperty + || assignmentKind === AssignmentDeclarationKind.Prototype; // A straight `Prototype` assignment probably can never have a computed name + if (isStatic === !isInstanceMember) { + if (hasLateBindableName(member)) { + lateBindMember(symbol, earlySymbols, lateSymbols, member); + } + } + } + } + + let resolved = combineSymbolTables(earlySymbols, lateSymbols); + if (symbol.flags & SymbolFlags.Transient && links.cjsExportMerged && symbol.declarations) { + for (const decl of symbol.declarations) { + const original = getSymbolLinks(decl.symbol)[resolutionKind]; + if (!resolved) { + resolved = original; + continue; + } + if (!original) continue; + original.forEach((s, name) => { + const existing = resolved!.get(name); + if (!existing) resolved!.set(name, s); + else if (existing === s) return; + else resolved!.set(name, mergeSymbol(existing, s)); + }); + } + } + links[resolutionKind] = resolved || emptySymbols; + } + + return links[resolutionKind]!; + } + + /** + * Gets a SymbolTable containing both the early- and late-bound members of a symbol. + * + * For a description of late-binding, see `lateBindMember`. + */ + function getMembersOfSymbol(symbol: Symbol) { + return symbol.flags & SymbolFlags.LateBindingContainer + ? getResolvedMembersOrExportsOfSymbol(symbol, MembersOrExportsResolutionKind.resolvedMembers) + : symbol.members || emptySymbols; + } + + /** + * If a symbol is the dynamic name of the member of an object type, get the late-bound + * symbol of the member. + * + * For a description of late-binding, see `lateBindMember`. + */ + function getLateBoundSymbol(symbol: Symbol): Symbol { + if (symbol.flags & SymbolFlags.ClassMember && symbol.escapedName === InternalSymbolName.Computed) { + const links = getSymbolLinks(symbol); + if (!links.lateSymbol && some(symbol.declarations, hasLateBindableName)) { + // force late binding of members/exports. This will set the late-bound symbol + const parent = getMergedSymbol(symbol.parent)!; + if (some(symbol.declarations, hasStaticModifier)) { + getExportsOfSymbol(parent); + } + else { + getMembersOfSymbol(parent); + } + } + return links.lateSymbol || (links.lateSymbol = symbol); + } + return symbol; + } + + function getTypeWithThisArgument(type: Type, thisArgument?: Type, needApparentType?: boolean): Type { + if (getObjectFlags(type) & ObjectFlags.Reference) { + const target = (type as TypeReference).target; + const typeArguments = getTypeArguments(type as TypeReference); + return length(target.typeParameters) === length(typeArguments) ? createTypeReference(target, concatenate(typeArguments, [thisArgument || target.thisType!])) : type; + } + else if (type.flags & TypeFlags.Intersection) { + const types = sameMap((type as IntersectionType).types, t => getTypeWithThisArgument(t, thisArgument, needApparentType)); + return types !== (type as IntersectionType).types ? getIntersectionType(types) : type; + } + return needApparentType ? getApparentType(type) : type; + } + + function resolveObjectTypeMembers(type: ObjectType, source: InterfaceTypeWithDeclaredMembers, typeParameters: readonly TypeParameter[], typeArguments: readonly Type[]) { + let mapper: TypeMapper | undefined; + let members: SymbolTable; + let callSignatures: readonly Signature[]; + let constructSignatures: readonly Signature[]; + let indexInfos: readonly IndexInfo[]; + if (rangeEquals(typeParameters, typeArguments, 0, typeParameters.length)) { + members = source.symbol ? getMembersOfSymbol(source.symbol) : createSymbolTable(source.declaredProperties); + callSignatures = source.declaredCallSignatures; + constructSignatures = source.declaredConstructSignatures; + indexInfos = source.declaredIndexInfos; + } + else { + mapper = createTypeMapper(typeParameters, typeArguments); + members = createInstantiatedSymbolTable(source.declaredProperties, mapper, /*mappingThisOnly*/ typeParameters.length === 1); + callSignatures = instantiateSignatures(source.declaredCallSignatures, mapper); + constructSignatures = instantiateSignatures(source.declaredConstructSignatures, mapper); + indexInfos = instantiateIndexInfos(source.declaredIndexInfos, mapper); + } + const baseTypes = getBaseTypes(source); + if (baseTypes.length) { + if (source.symbol && members === getMembersOfSymbol(source.symbol)) { + const symbolTable = createSymbolTable(source.declaredProperties); + // copy index signature symbol as well (for quickinfo) + const sourceIndex = getIndexSymbol(source.symbol); + if (sourceIndex) { + symbolTable.set(InternalSymbolName.Index, sourceIndex); + } + members = symbolTable; + } + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + const thisArgument = lastOrUndefined(typeArguments); + for (const baseType of baseTypes) { + const instantiatedBaseType = thisArgument ? getTypeWithThisArgument(instantiateType(baseType, mapper), thisArgument) : baseType; + addInheritedMembers(members, getPropertiesOfType(instantiatedBaseType)); + callSignatures = concatenate(callSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Call)); + constructSignatures = concatenate(constructSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Construct)); + const inheritedIndexInfos = instantiatedBaseType !== anyType ? getIndexInfosOfType(instantiatedBaseType) : [createIndexInfo(stringType, anyType, /*isReadonly*/ false)]; + indexInfos = concatenate(indexInfos, filter(inheritedIndexInfos, info => !findIndexInfo(indexInfos, info.keyType))); + } + } + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + } + + function resolveClassOrInterfaceMembers(type: InterfaceType): void { + resolveObjectTypeMembers(type, resolveDeclaredMembers(type), emptyArray, emptyArray); + } + + function resolveTypeReferenceMembers(type: TypeReference): void { + const source = resolveDeclaredMembers(type.target); + const typeParameters = concatenate(source.typeParameters!, [source.thisType!]); + const typeArguments = getTypeArguments(type); + const paddedTypeArguments = typeArguments.length === typeParameters.length ? typeArguments : concatenate(typeArguments, [type]); + resolveObjectTypeMembers(type, source, typeParameters, paddedTypeArguments); + } + + function createSignature( + declaration: SignatureDeclaration | JSDocSignature | undefined, + typeParameters: readonly TypeParameter[] | undefined, + thisParameter: Symbol | undefined, + parameters: readonly Symbol[], + resolvedReturnType: Type | undefined, + resolvedTypePredicate: TypePredicate | undefined, + minArgumentCount: number, + flags: SignatureFlags, + ): Signature { + const sig = new Signature(checker, flags); + sig.declaration = declaration; + sig.typeParameters = typeParameters; + sig.parameters = parameters; + sig.thisParameter = thisParameter; + sig.resolvedReturnType = resolvedReturnType; + sig.resolvedTypePredicate = resolvedTypePredicate; + sig.minArgumentCount = minArgumentCount; + sig.resolvedMinArgumentCount = undefined; + sig.target = undefined; + sig.mapper = undefined; + sig.compositeSignatures = undefined; + sig.compositeKind = undefined; + return sig; + } + + function cloneSignature(sig: Signature): Signature { + const result = createSignature(sig.declaration, sig.typeParameters, sig.thisParameter, sig.parameters, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, sig.minArgumentCount, sig.flags & SignatureFlags.PropagatingFlags); + result.target = sig.target; + result.mapper = sig.mapper; + result.compositeSignatures = sig.compositeSignatures; + result.compositeKind = sig.compositeKind; + return result; + } + + function createUnionSignature(signature: Signature, unionSignatures: Signature[]) { + const result = cloneSignature(signature); + result.compositeSignatures = unionSignatures; + result.compositeKind = TypeFlags.Union; + result.target = undefined; + result.mapper = undefined; + return result; + } + + function getOptionalCallSignature(signature: Signature, callChainFlags: SignatureFlags): Signature { + if ((signature.flags & SignatureFlags.CallChainFlags) === callChainFlags) { + return signature; + } + if (!signature.optionalCallSignatureCache) { + signature.optionalCallSignatureCache = {}; + } + const key = callChainFlags === SignatureFlags.IsInnerCallChain ? "inner" : "outer"; + return signature.optionalCallSignatureCache[key] + || (signature.optionalCallSignatureCache[key] = createOptionalCallSignature(signature, callChainFlags)); + } + + function createOptionalCallSignature(signature: Signature, callChainFlags: SignatureFlags) { + Debug.assert(callChainFlags === SignatureFlags.IsInnerCallChain || callChainFlags === SignatureFlags.IsOuterCallChain, "An optional call signature can either be for an inner call chain or an outer call chain, but not both."); + const result = cloneSignature(signature); + result.flags |= callChainFlags; + return result; + } + + function getExpandedParameters(sig: Signature, skipUnionExpanding?: boolean): readonly (readonly Symbol[])[] { + if (signatureHasRestParameter(sig)) { + const restIndex = sig.parameters.length - 1; + const restName = sig.parameters[restIndex].escapedName; + const restType = getTypeOfSymbol(sig.parameters[restIndex]); + if (isTupleType(restType)) { + return [expandSignatureParametersWithTupleMembers(restType, restIndex, restName)]; + } + else if (!skipUnionExpanding && restType.flags & TypeFlags.Union && every((restType as UnionType).types, isTupleType)) { + return map((restType as UnionType).types, t => expandSignatureParametersWithTupleMembers(t as TupleTypeReference, restIndex, restName)); + } + } + return [sig.parameters]; + + function expandSignatureParametersWithTupleMembers(restType: TupleTypeReference, restIndex: number, restName: __String) { + const elementTypes = getTypeArguments(restType); + const associatedNames = getUniqAssociatedNamesFromTupleType(restType, restName); + const restParams = map(elementTypes, (t, i) => { + // Lookup the label from the individual tuple passed in before falling back to the signature `rest` parameter name + const name = associatedNames && associatedNames[i] ? associatedNames[i] : + getParameterNameAtPosition(sig, restIndex + i, restType); + const flags = restType.target.elementFlags[i]; + const checkFlags = flags & ElementFlags.Variable ? CheckFlags.RestParameter : + flags & ElementFlags.Optional ? CheckFlags.OptionalParameter : 0; + const symbol = createSymbol(SymbolFlags.FunctionScopedVariable, name, checkFlags); + symbol.links.type = flags & ElementFlags.Rest ? createArrayType(t) : t; + return symbol; + }); + return concatenate(sig.parameters.slice(0, restIndex), restParams); + } + + function getUniqAssociatedNamesFromTupleType(type: TupleTypeReference, restName: __String) { + const associatedNamesMap = new Map<__String, number>(); + return map(type.target.labeledElementDeclarations, (labeledElement, i) => { + const name = getTupleElementLabel(labeledElement, i, restName); + const prevCounter = associatedNamesMap.get(name); + if (prevCounter === undefined) { + associatedNamesMap.set(name, 1); + return name; + } + else { + associatedNamesMap.set(name, prevCounter + 1); + return `${name}_${prevCounter}` as __String; + } + }); + } + } + + function getDefaultConstructSignatures(classType: InterfaceType): Signature[] { + const baseConstructorType = getBaseConstructorTypeOfClass(classType); + const baseSignatures = getSignaturesOfType(baseConstructorType, SignatureKind.Construct); + const declaration = getClassLikeDeclarationOfSymbol(classType.symbol); + const isAbstract = !!declaration && hasSyntacticModifier(declaration, ModifierFlags.Abstract); + if (baseSignatures.length === 0) { + return [createSignature(/*declaration*/ undefined, classType.localTypeParameters, /*thisParameter*/ undefined, emptyArray, classType, /*resolvedTypePredicate*/ undefined, 0, isAbstract ? SignatureFlags.Abstract : SignatureFlags.None)]; + } + const baseTypeNode = getBaseTypeNodeOfClass(classType)!; + const isJavaScript = isInJSFile(baseTypeNode); + const typeArguments = typeArgumentsFromTypeReferenceNode(baseTypeNode); + const typeArgCount = length(typeArguments); + const result: Signature[] = []; + for (const baseSig of baseSignatures) { + const minTypeArgumentCount = getMinTypeArgumentCount(baseSig.typeParameters); + const typeParamCount = length(baseSig.typeParameters); + if (isJavaScript || typeArgCount >= minTypeArgumentCount && typeArgCount <= typeParamCount) { + const sig = typeParamCount ? createSignatureInstantiation(baseSig, fillMissingTypeArguments(typeArguments, baseSig.typeParameters, minTypeArgumentCount, isJavaScript)) : cloneSignature(baseSig); + sig.typeParameters = classType.localTypeParameters; + sig.resolvedReturnType = classType; + sig.flags = isAbstract ? sig.flags | SignatureFlags.Abstract : sig.flags & ~SignatureFlags.Abstract; + result.push(sig); + } + } + return result; + } + + function findMatchingSignature(signatureList: readonly Signature[], signature: Signature, partialMatch: boolean, ignoreThisTypes: boolean, ignoreReturnTypes: boolean): Signature | undefined { + for (const s of signatureList) { + if (compareSignaturesIdentical(s, signature, partialMatch, ignoreThisTypes, ignoreReturnTypes, partialMatch ? compareTypesSubtypeOf : compareTypesIdentical)) { + return s; + } + } + } + + function findMatchingSignatures(signatureLists: readonly (readonly Signature[])[], signature: Signature, listIndex: number): Signature[] | undefined { + if (signature.typeParameters) { + // We require an exact match for generic signatures, so we only return signatures from the first + // signature list and only if they have exact matches in the other signature lists. + if (listIndex > 0) { + return undefined; + } + for (let i = 1; i < signatureLists.length; i++) { + if (!findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false)) { + return undefined; + } + } + return [signature]; + } + let result: Signature[] | undefined; + for (let i = 0; i < signatureLists.length; i++) { + // Allow matching non-generic signatures to have excess parameters (as a fallback if exact parameter match is not found) and different return types. + // Prefer matching this types if possible. + const match = i === listIndex + ? signature + : findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true) + || findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ true, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true); + if (!match) { + return undefined; + } + result = appendIfUnique(result, match); + } + return result; + } + + // The signatures of a union type are those signatures that are present in each of the constituent types. + // Generic signatures must match exactly, but non-generic signatures are allowed to have extra optional + // parameters and may differ in return types. When signatures differ in return types, the resulting return + // type is the union of the constituent return types. + function getUnionSignatures(signatureLists: readonly (readonly Signature[])[]): Signature[] { + let result: Signature[] | undefined; + let indexWithLengthOverOne: number | undefined; + for (let i = 0; i < signatureLists.length; i++) { + if (signatureLists[i].length === 0) return emptyArray; + if (signatureLists[i].length > 1) { + indexWithLengthOverOne = indexWithLengthOverOne === undefined ? i : -1; // -1 is a signal there are multiple overload sets + } + for (const signature of signatureLists[i]) { + // Only process signatures with parameter lists that aren't already in the result list + if (!result || !findMatchingSignature(result, signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true)) { + const unionSignatures = findMatchingSignatures(signatureLists, signature, i); + if (unionSignatures) { + let s = signature; + // Union the result types when more than one signature matches + if (unionSignatures.length > 1) { + let thisParameter = signature.thisParameter; + const firstThisParameterOfUnionSignatures = forEach(unionSignatures, sig => sig.thisParameter); + if (firstThisParameterOfUnionSignatures) { + const thisType = getIntersectionType(mapDefined(unionSignatures, sig => sig.thisParameter && getTypeOfSymbol(sig.thisParameter))); + thisParameter = createSymbolWithType(firstThisParameterOfUnionSignatures, thisType); + } + s = createUnionSignature(signature, unionSignatures); + s.thisParameter = thisParameter; + } + (result || (result = [])).push(s); + } + } + } + } + if (!length(result) && indexWithLengthOverOne !== -1) { + // No sufficiently similar signature existed to subsume all the other signatures in the union - time to see if we can make a single + // signature that handles all over them. We only do this when there are overloads in only one constituent. + // (Overloads are conditional in nature and having overloads in multiple constituents would necessitate making a power set of + // signatures from the type, whose ordering would be non-obvious) + const masterList = signatureLists[indexWithLengthOverOne !== undefined ? indexWithLengthOverOne : 0]; + let results: Signature[] | undefined = masterList.slice(); + for (const signatures of signatureLists) { + if (signatures !== masterList) { + const signature = signatures[0]; + Debug.assert(!!signature, "getUnionSignatures bails early on empty signature lists and should not have empty lists on second pass"); + results = !!signature.typeParameters && some(results, s => !!s.typeParameters && !compareTypeParametersIdentical(signature.typeParameters, s.typeParameters)) ? undefined : map(results, sig => combineSignaturesOfUnionMembers(sig, signature)); + if (!results) { + break; + } + } + } + result = results; + } + return result || emptyArray; + } + + function compareTypeParametersIdentical(sourceParams: readonly TypeParameter[] | undefined, targetParams: readonly TypeParameter[] | undefined): boolean { + if (length(sourceParams) !== length(targetParams)) { + return false; + } + if (!sourceParams || !targetParams) { + return true; + } + + const mapper = createTypeMapper(targetParams, sourceParams); + for (let i = 0; i < sourceParams.length; i++) { + const source = sourceParams[i]; + const target = targetParams[i]; + if (source === target) continue; + // We instantiate the target type parameter constraints into the source types so we can recognize `` as the same as `` + if (!isTypeIdenticalTo(getConstraintFromTypeParameter(source) || unknownType, instantiateType(getConstraintFromTypeParameter(target) || unknownType, mapper))) return false; + // We don't compare defaults - we just use the type parameter defaults from the first signature that seems to match. + // It might make sense to combine these defaults in the future, but doing so intelligently requires knowing + // if the parameter is used covariantly or contravariantly (so we intersect if it's used like a parameter or union if used like a return type) + // and, since it's just an inference _default_, just picking one arbitrarily works OK. + } + + return true; + } + + function combineUnionThisParam(left: Symbol | undefined, right: Symbol | undefined, mapper: TypeMapper | undefined): Symbol | undefined { + if (!left || !right) { + return left || right; + } + // A signature `this` type might be a read or a write position... It's very possible that it should be invariant + // and we should refuse to merge signatures if there are `this` types and they do not match. However, so as to be + // permissive when calling, for now, we'll intersect the `this` types just like we do for param types in union signatures. + const thisType = getIntersectionType([getTypeOfSymbol(left), instantiateType(getTypeOfSymbol(right), mapper)]); + return createSymbolWithType(left, thisType); + } + + function combineUnionParameters(left: Signature, right: Signature, mapper: TypeMapper | undefined) { + const leftCount = getParameterCount(left); + const rightCount = getParameterCount(right); + const longest = leftCount >= rightCount ? left : right; + const shorter = longest === left ? right : left; + const longestCount = longest === left ? leftCount : rightCount; + const eitherHasEffectiveRest = hasEffectiveRestParameter(left) || hasEffectiveRestParameter(right); + const needsExtraRestElement = eitherHasEffectiveRest && !hasEffectiveRestParameter(longest); + const params = new Array(longestCount + (needsExtraRestElement ? 1 : 0)); + for (let i = 0; i < longestCount; i++) { + let longestParamType = tryGetTypeAtPosition(longest, i)!; + if (longest === right) { + longestParamType = instantiateType(longestParamType, mapper); + } + let shorterParamType = tryGetTypeAtPosition(shorter, i) || unknownType; + if (shorter === right) { + shorterParamType = instantiateType(shorterParamType, mapper); + } + const unionParamType = getIntersectionType([longestParamType, shorterParamType]); + const isRestParam = eitherHasEffectiveRest && !needsExtraRestElement && i === (longestCount - 1); + const isOptional = i >= getMinArgumentCount(longest) && i >= getMinArgumentCount(shorter); + const leftName = i >= leftCount ? undefined : getParameterNameAtPosition(left, i); + const rightName = i >= rightCount ? undefined : getParameterNameAtPosition(right, i); + + const paramName = leftName === rightName ? leftName : + !leftName ? rightName : + !rightName ? leftName : + undefined; + const paramSymbol = createSymbol( + SymbolFlags.FunctionScopedVariable | (isOptional && !isRestParam ? SymbolFlags.Optional : 0), + paramName || `arg${i}` as __String, + isRestParam ? CheckFlags.RestParameter : isOptional ? CheckFlags.OptionalParameter : 0, + ); + paramSymbol.links.type = isRestParam ? createArrayType(unionParamType) : unionParamType; + params[i] = paramSymbol; + } + if (needsExtraRestElement) { + const restParamSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "args" as __String, CheckFlags.RestParameter); + restParamSymbol.links.type = createArrayType(getTypeAtPosition(shorter, longestCount)); + if (shorter === right) { + restParamSymbol.links.type = instantiateType(restParamSymbol.links.type, mapper); + } + params[longestCount] = restParamSymbol; + } + return params; + } + + function combineSignaturesOfUnionMembers(left: Signature, right: Signature): Signature { + const typeParams = left.typeParameters || right.typeParameters; + let paramMapper: TypeMapper | undefined; + if (left.typeParameters && right.typeParameters) { + paramMapper = createTypeMapper(right.typeParameters, left.typeParameters); + // We just use the type parameter defaults from the first signature + } + const declaration = left.declaration; + const params = combineUnionParameters(left, right, paramMapper); + const thisParam = combineUnionThisParam(left.thisParameter, right.thisParameter, paramMapper); + const minArgCount = Math.max(left.minArgumentCount, right.minArgumentCount); + const result = createSignature( + declaration, + typeParams, + thisParam, + params, + /*resolvedReturnType*/ undefined, + /*resolvedTypePredicate*/ undefined, + minArgCount, + (left.flags | right.flags) & SignatureFlags.PropagatingFlags, + ); + result.compositeKind = TypeFlags.Union; + result.compositeSignatures = concatenate(left.compositeKind !== TypeFlags.Intersection && left.compositeSignatures || [left], [right]); + if (paramMapper) { + result.mapper = left.compositeKind !== TypeFlags.Intersection && left.mapper && left.compositeSignatures ? combineTypeMappers(left.mapper, paramMapper) : paramMapper; + } + else if (left.compositeKind !== TypeFlags.Intersection && left.mapper && left.compositeSignatures) { + result.mapper = left.mapper; + } + return result; + } + + function getUnionIndexInfos(types: readonly Type[]): IndexInfo[] { + const sourceInfos = getIndexInfosOfType(types[0]); + if (sourceInfos) { + const result = []; + for (const info of sourceInfos) { + const indexType = info.keyType; + if (every(types, t => !!getIndexInfoOfType(t, indexType))) { + result.push(createIndexInfo(indexType, getUnionType(map(types, t => getIndexTypeOfType(t, indexType)!)), some(types, t => getIndexInfoOfType(t, indexType)!.isReadonly))); + } + } + return result; + } + return emptyArray; + } + + function resolveUnionTypeMembers(type: UnionType) { + // The members and properties collections are empty for union types. To get all properties of a union + // type use getPropertiesOfType (only the language service uses this). + const callSignatures = getUnionSignatures(map(type.types, t => t === globalFunctionType ? [unknownSignature] : getSignaturesOfType(t, SignatureKind.Call))); + const constructSignatures = getUnionSignatures(map(type.types, t => getSignaturesOfType(t, SignatureKind.Construct))); + const indexInfos = getUnionIndexInfos(type.types); + setStructuredTypeMembers(type, emptySymbols, callSignatures, constructSignatures, indexInfos); + } + + function intersectTypes(type1: Type, type2: Type): Type; + function intersectTypes(type1: Type | undefined, type2: Type | undefined): Type | undefined; + function intersectTypes(type1: Type | undefined, type2: Type | undefined): Type | undefined { + return !type1 ? type2 : !type2 ? type1 : getIntersectionType([type1, type2]); + } + + function findMixins(types: readonly Type[]): readonly boolean[] { + const constructorTypeCount = countWhere(types, t => getSignaturesOfType(t, SignatureKind.Construct).length > 0); + const mixinFlags = map(types, isMixinConstructorType); + if (constructorTypeCount > 0 && constructorTypeCount === countWhere(mixinFlags, b => b)) { + const firstMixinIndex = mixinFlags.indexOf(/*searchElement*/ true); + mixinFlags[firstMixinIndex] = false; + } + return mixinFlags; + } + + function includeMixinType(type: Type, types: readonly Type[], mixinFlags: readonly boolean[], index: number): Type { + const mixedTypes: Type[] = []; + for (let i = 0; i < types.length; i++) { + if (i === index) { + mixedTypes.push(type); + } + else if (mixinFlags[i]) { + mixedTypes.push(getReturnTypeOfSignature(getSignaturesOfType(types[i], SignatureKind.Construct)[0])); + } + } + return getIntersectionType(mixedTypes); + } + + function resolveIntersectionTypeMembers(type: IntersectionType) { + // The members and properties collections are empty for intersection types. To get all properties of an + // intersection type use getPropertiesOfType (only the language service uses this). + let callSignatures: Signature[] | undefined; + let constructSignatures: Signature[] | undefined; + let indexInfos: IndexInfo[] | undefined; + const types = type.types; + const mixinFlags = findMixins(types); + const mixinCount = countWhere(mixinFlags, b => b); + for (let i = 0; i < types.length; i++) { + const t = type.types[i]; + // When an intersection type contains mixin constructor types, the construct signatures from + // those types are discarded and their return types are mixed into the return types of all + // other construct signatures in the intersection type. For example, the intersection type + // '{ new(...args: any[]) => A } & { new(s: string) => B }' has a single construct signature + // 'new(s: string) => A & B'. + if (!mixinFlags[i]) { + let signatures = getSignaturesOfType(t, SignatureKind.Construct); + if (signatures.length && mixinCount > 0) { + signatures = map(signatures, s => { + const clone = cloneSignature(s); + clone.resolvedReturnType = includeMixinType(getReturnTypeOfSignature(s), types, mixinFlags, i); + return clone; + }); + } + constructSignatures = appendSignatures(constructSignatures, signatures); + } + callSignatures = appendSignatures(callSignatures, getSignaturesOfType(t, SignatureKind.Call)); + indexInfos = reduceLeft(getIndexInfosOfType(t), (infos, newInfo) => appendIndexInfo(infos, newInfo, /*union*/ false), indexInfos); + } + setStructuredTypeMembers(type, emptySymbols, callSignatures || emptyArray, constructSignatures || emptyArray, indexInfos || emptyArray); + } + + function appendSignatures(signatures: Signature[] | undefined, newSignatures: readonly Signature[]) { + for (const sig of newSignatures) { + if (!signatures || every(signatures, s => !compareSignaturesIdentical(s, sig, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false, compareTypesIdentical))) { + signatures = append(signatures, sig); + } + } + return signatures; + } + + function appendIndexInfo(indexInfos: IndexInfo[] | undefined, newInfo: IndexInfo, union: boolean) { + if (indexInfos) { + for (let i = 0; i < indexInfos.length; i++) { + const info = indexInfos[i]; + if (info.keyType === newInfo.keyType) { + indexInfos[i] = createIndexInfo(info.keyType, union ? getUnionType([info.type, newInfo.type]) : getIntersectionType([info.type, newInfo.type]), union ? info.isReadonly || newInfo.isReadonly : info.isReadonly && newInfo.isReadonly); + return indexInfos; + } + } + } + return append(indexInfos, newInfo); + } + + /** + * Converts an AnonymousType to a ResolvedType. + */ + function resolveAnonymousTypeMembers(type: AnonymousType) { + if (type.target) { + setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); + const members = createInstantiatedSymbolTable(getPropertiesOfObjectType(type.target), type.mapper!, /*mappingThisOnly*/ false); + const callSignatures = instantiateSignatures(getSignaturesOfType(type.target, SignatureKind.Call), type.mapper!); + const constructSignatures = instantiateSignatures(getSignaturesOfType(type.target, SignatureKind.Construct), type.mapper!); + const indexInfos = instantiateIndexInfos(getIndexInfosOfType(type.target), type.mapper!); + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + return; + } + const symbol = getMergedSymbol(type.symbol); + if (symbol.flags & SymbolFlags.TypeLiteral) { + setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); + const members = getMembersOfSymbol(symbol); + const callSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.Call)); + const constructSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.New)); + const indexInfos = getIndexInfosOfSymbol(symbol); + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + return; + } + // Combinations of function, class, enum and module + let members = getExportsOfSymbol(symbol); + let indexInfos: IndexInfo[] | undefined; + if (symbol === globalThisSymbol) { + const varsOnly = new Map<__String, Symbol>(); + members.forEach(p => { + if (!(p.flags & SymbolFlags.BlockScoped) && !(p.flags & SymbolFlags.ValueModule && p.declarations?.length && every(p.declarations, isAmbientModule))) { + varsOnly.set(p.escapedName, p); + } + }); + members = varsOnly; + } + let baseConstructorIndexInfo: IndexInfo | undefined; + setStructuredTypeMembers(type, members, emptyArray, emptyArray, emptyArray); + if (symbol.flags & SymbolFlags.Class) { + const classType = getDeclaredTypeOfClassOrInterface(symbol); + const baseConstructorType = getBaseConstructorTypeOfClass(classType); + if (baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.TypeVariable)) { + members = createSymbolTable(getNamedOrIndexSignatureMembers(members)); + addInheritedMembers(members, getPropertiesOfType(baseConstructorType)); + } + else if (baseConstructorType === anyType) { + baseConstructorIndexInfo = createIndexInfo(stringType, anyType, /*isReadonly*/ false); + } + } + + const indexSymbol = getIndexSymbolFromSymbolTable(members); + if (indexSymbol) { + indexInfos = getIndexInfosOfIndexSymbol(indexSymbol); + } + else { + if (baseConstructorIndexInfo) { + indexInfos = append(indexInfos, baseConstructorIndexInfo); + } + if ( + symbol.flags & SymbolFlags.Enum && (getDeclaredTypeOfSymbol(symbol).flags & TypeFlags.Enum || + some(type.properties, prop => !!(getTypeOfSymbol(prop).flags & TypeFlags.NumberLike))) + ) { + indexInfos = append(indexInfos, enumNumberIndexInfo); + } + } + setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos || emptyArray); + // We resolve the members before computing the signatures because a signature may use + // typeof with a qualified name expression that circularly references the type we are + // in the process of resolving (see issue #6072). The temporarily empty signature list + // will never be observed because a qualified name can't reference signatures. + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method)) { + type.callSignatures = getSignaturesOfSymbol(symbol); + } + // And likewise for construct signatures for classes + if (symbol.flags & SymbolFlags.Class) { + const classType = getDeclaredTypeOfClassOrInterface(symbol); + let constructSignatures = symbol.members ? getSignaturesOfSymbol(symbol.members.get(InternalSymbolName.Constructor)) : emptyArray; + if (symbol.flags & SymbolFlags.Function) { + constructSignatures = addRange( + constructSignatures.slice(), + mapDefined( + type.callSignatures, + sig => + isJSConstructor(sig.declaration) ? + createSignature(sig.declaration, sig.typeParameters, sig.thisParameter, sig.parameters, classType, /*resolvedTypePredicate*/ undefined, sig.minArgumentCount, sig.flags & SignatureFlags.PropagatingFlags) : + undefined, + ), + ); + } + if (!constructSignatures.length) { + constructSignatures = getDefaultConstructSignatures(classType); + } + type.constructSignatures = constructSignatures; + } + } + + type ReplaceableIndexedAccessType = IndexedAccessType & { objectType: TypeParameter; indexType: TypeParameter; }; + function replaceIndexedAccess(instantiable: Type, type: ReplaceableIndexedAccessType, replacement: Type) { + // map type.indexType to 0 + // map type.objectType to `[TReplacement]` + // thus making the indexed access `[TReplacement][0]` or `TReplacement` + return instantiateType(instantiable, createTypeMapper([type.indexType, type.objectType], [getNumberLiteralType(0), createTupleType([replacement])])); + } + + // If the original mapped type had an intersection constraint we extract its components, + // and we make an attempt to do so even if the intersection has been reduced to a union. + // This entire process allows us to possibly retrieve the filtering type literals. + // e.g. { [K in keyof U & ("a" | "b") ] } -> "a" | "b" + function getLimitedConstraint(type: ReverseMappedType) { + const constraint = getConstraintTypeFromMappedType(type.mappedType); + if (!(constraint.flags & TypeFlags.Union || constraint.flags & TypeFlags.Intersection)) { + return; + } + const origin = (constraint.flags & TypeFlags.Union) ? (constraint as UnionType).origin : (constraint as IntersectionType); + if (!origin || !(origin.flags & TypeFlags.Intersection)) { + return; + } + const limitedConstraint = getIntersectionType((origin as IntersectionType).types.filter(t => t !== type.constraintType)); + return limitedConstraint !== neverType ? limitedConstraint : undefined; + } + + function resolveReverseMappedTypeMembers(type: ReverseMappedType) { + const indexInfo = getIndexInfoOfType(type.source, stringType); + const modifiers = getMappedTypeModifiers(type.mappedType); + const readonlyMask = modifiers & MappedTypeModifiers.IncludeReadonly ? false : true; + const optionalMask = modifiers & MappedTypeModifiers.IncludeOptional ? 0 : SymbolFlags.Optional; + const indexInfos = indexInfo ? [createIndexInfo(stringType, inferReverseMappedType(indexInfo.type, type.mappedType, type.constraintType) || unknownType, readonlyMask && indexInfo.isReadonly)] : emptyArray; + const members = createSymbolTable(); + const limitedConstraint = getLimitedConstraint(type); + for (const prop of getPropertiesOfType(type.source)) { + // In case of a reverse mapped type with an intersection constraint, if we were able to + // extract the filtering type literals we skip those properties that are not assignable to them, + // because the extra properties wouldn't get through the application of the mapped type anyway + if (limitedConstraint) { + const propertyNameType = getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique); + if (!isTypeAssignableTo(propertyNameType, limitedConstraint)) { + continue; + } + } + const checkFlags = CheckFlags.ReverseMapped | (readonlyMask && isReadonlySymbol(prop) ? CheckFlags.Readonly : 0); + const inferredProp = createSymbol(SymbolFlags.Property | prop.flags & optionalMask, prop.escapedName, checkFlags) as ReverseMappedSymbol; + inferredProp.declarations = prop.declarations; + inferredProp.links.nameType = getSymbolLinks(prop).nameType; + inferredProp.links.propertyType = getTypeOfSymbol(prop); + if ( + type.constraintType.type.flags & TypeFlags.IndexedAccess + && (type.constraintType.type as IndexedAccessType).objectType.flags & TypeFlags.TypeParameter + && (type.constraintType.type as IndexedAccessType).indexType.flags & TypeFlags.TypeParameter + ) { + // A reverse mapping of `{[K in keyof T[K_1]]: T[K_1]}` is the same as that of `{[K in keyof T]: T}`, since all we care about is + // inferring to the "type parameter" (or indexed access) shared by the constraint and template. So, to reduce the number of + // type identities produced, we simplify such indexed access occurences + const newTypeParam = (type.constraintType.type as IndexedAccessType).objectType; + const newMappedType = replaceIndexedAccess(type.mappedType, type.constraintType.type as ReplaceableIndexedAccessType, newTypeParam); + inferredProp.links.mappedType = newMappedType as MappedType; + inferredProp.links.constraintType = getIndexType(newTypeParam) as IndexType; + } + else { + inferredProp.links.mappedType = type.mappedType; + inferredProp.links.constraintType = type.constraintType; + } + members.set(prop.escapedName, inferredProp); + } + setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos); + } + + // Return the lower bound of the key type in a mapped type. Intuitively, the lower + // bound includes those keys that are known to always be present, for example because + // because of constraints on type parameters (e.g. 'keyof T' for a constrained T). + function getLowerBoundOfKeyType(type: Type): Type { + if (type.flags & TypeFlags.Index) { + const t = getApparentType((type as IndexType).type); + return isGenericTupleType(t) ? getKnownKeysOfTupleType(t) : getIndexType(t); + } + if (type.flags & TypeFlags.Conditional) { + if ((type as ConditionalType).root.isDistributive) { + const checkType = (type as ConditionalType).checkType; + const constraint = getLowerBoundOfKeyType(checkType); + if (constraint !== checkType) { + return getConditionalTypeInstantiation(type as ConditionalType, prependTypeMapping((type as ConditionalType).root.checkType, constraint, (type as ConditionalType).mapper), /*forConstraint*/ false); + } + } + return type; + } + if (type.flags & TypeFlags.Union) { + return mapType(type as UnionType, getLowerBoundOfKeyType, /*noReductions*/ true); + } + if (type.flags & TypeFlags.Intersection) { + // Similarly to getTypeFromIntersectionTypeNode, we preserve the special string & {}, number & {}, + // and bigint & {} intersections that are used to prevent subtype reduction in union types. + const types = (type as IntersectionType).types; + if (types.length === 2 && !!(types[0].flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt)) && types[1] === emptyTypeLiteralType) { + return type; + } + return getIntersectionType(sameMap((type as UnionType).types, getLowerBoundOfKeyType)); + } + return type; + } + + function getIsLateCheckFlag(s: Symbol): CheckFlags { + return getCheckFlags(s) & CheckFlags.Late; + } + + function forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(type: Type, include: TypeFlags, stringsOnly: boolean, cb: (keyType: Type) => void) { + for (const prop of getPropertiesOfType(type)) { + cb(getLiteralTypeFromProperty(prop, include)); + } + if (type.flags & TypeFlags.Any) { + cb(stringType); + } + else { + for (const info of getIndexInfosOfType(type)) { + if (!stringsOnly || info.keyType.flags & (TypeFlags.String | TypeFlags.TemplateLiteral)) { + cb(info.keyType); + } + } + } + } + + /** Resolve the members of a mapped type { [P in K]: T } */ + function resolveMappedTypeMembers(type: MappedType) { + const members: SymbolTable = createSymbolTable(); + let indexInfos: IndexInfo[] | undefined; + // Resolve upfront such that recursive references see an empty object type. + setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); + // In { [P in K]: T }, we refer to P as the type parameter type, K as the constraint type, + // and T as the template type. + const typeParameter = getTypeParameterFromMappedType(type); + const constraintType = getConstraintTypeFromMappedType(type); + const mappedType = (type.target as MappedType) || type; + const nameType = getNameTypeFromMappedType(mappedType); + const shouldLinkPropDeclarations = getMappedTypeNameTypeKind(mappedType) !== MappedTypeNameTypeKind.Remapping; + const templateType = getTemplateTypeFromMappedType(mappedType); + const modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T' + const templateModifiers = getMappedTypeModifiers(type); + const include = TypeFlags.StringOrNumberLiteralOrUnique; + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // We have a { [P in keyof T]: X } + forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(modifiersType, include, /*stringsOnly*/ false, addMemberForKeyType); + } + else { + forEachType(getLowerBoundOfKeyType(constraintType), addMemberForKeyType); + } + setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos || emptyArray); + + function addMemberForKeyType(keyType: Type) { + const propNameType = nameType ? instantiateType(nameType, appendTypeMapping(type.mapper, typeParameter, keyType)) : keyType; + forEachType(propNameType, t => addMemberForKeyTypeWorker(keyType, t)); + } + + function addMemberForKeyTypeWorker(keyType: Type, propNameType: Type) { + // If the current iteration type constituent is a string literal type, create a property. + // Otherwise, for type string create a string index signature. + if (isTypeUsableAsPropertyName(propNameType)) { + const propName = getPropertyNameFromType(propNameType); + // String enum members from separate enums with identical values + // are distinct types with the same property name. Make the resulting + // property symbol's name type be the union of those enum member types. + const existingProp = members.get(propName) as MappedSymbol | undefined; + if (existingProp) { + existingProp.links.nameType = getUnionType([existingProp.links.nameType!, propNameType]); + existingProp.links.keyType = getUnionType([existingProp.links.keyType, keyType]); + } + else { + const modifiersProp = isTypeUsableAsPropertyName(keyType) ? getPropertyOfType(modifiersType, getPropertyNameFromType(keyType)) : undefined; + const isOptional = !!(templateModifiers & MappedTypeModifiers.IncludeOptional || + !(templateModifiers & MappedTypeModifiers.ExcludeOptional) && modifiersProp && modifiersProp.flags & SymbolFlags.Optional); + const isReadonly = !!(templateModifiers & MappedTypeModifiers.IncludeReadonly || + !(templateModifiers & MappedTypeModifiers.ExcludeReadonly) && modifiersProp && isReadonlySymbol(modifiersProp)); + const stripOptional = strictNullChecks && !isOptional && modifiersProp && modifiersProp.flags & SymbolFlags.Optional; + const lateFlag: CheckFlags = modifiersProp ? getIsLateCheckFlag(modifiersProp) : 0; + const prop = createSymbol(SymbolFlags.Property | (isOptional ? SymbolFlags.Optional : 0), propName, lateFlag | CheckFlags.Mapped | (isReadonly ? CheckFlags.Readonly : 0) | (stripOptional ? CheckFlags.StripOptional : 0)) as MappedSymbol; + prop.links.mappedType = type; + prop.links.nameType = propNameType; + prop.links.keyType = keyType; + if (modifiersProp) { + prop.links.syntheticOrigin = modifiersProp; + prop.declarations = shouldLinkPropDeclarations ? modifiersProp.declarations : undefined; + } + members.set(propName, prop); + } + } + else if (isValidIndexKeyType(propNameType) || propNameType.flags & (TypeFlags.Any | TypeFlags.Enum)) { + const indexKeyType = propNameType.flags & (TypeFlags.Any | TypeFlags.String) ? stringType : + propNameType.flags & (TypeFlags.Number | TypeFlags.Enum) ? numberType : + propNameType; + const propType = instantiateType(templateType, appendTypeMapping(type.mapper, typeParameter, keyType)); + const modifiersIndexInfo = getApplicableIndexInfo(modifiersType, propNameType); + const isReadonly = !!(templateModifiers & MappedTypeModifiers.IncludeReadonly || + !(templateModifiers & MappedTypeModifiers.ExcludeReadonly) && modifiersIndexInfo?.isReadonly); + const indexInfo = createIndexInfo(indexKeyType, propType, isReadonly); + indexInfos = appendIndexInfo(indexInfos, indexInfo, /*union*/ true); + } + } + } + + function getTypeOfMappedSymbol(symbol: MappedSymbol) { + if (!symbol.links.type) { + const mappedType = symbol.links.mappedType; + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + mappedType.containsError = true; + return errorType; + } + const templateType = getTemplateTypeFromMappedType(mappedType.target as MappedType || mappedType); + const mapper = appendTypeMapping(mappedType.mapper, getTypeParameterFromMappedType(mappedType), symbol.links.keyType); + const propType = instantiateType(templateType, mapper); + // When creating an optional property in strictNullChecks mode, if 'undefined' isn't assignable to the + // type, we include 'undefined' in the type. Similarly, when creating a non-optional property in strictNullChecks + // mode, if the underlying property is optional we remove 'undefined' from the type. + let type = strictNullChecks && symbol.flags & SymbolFlags.Optional && !maybeTypeOfKind(propType, TypeFlags.Undefined | TypeFlags.Void) ? getOptionalType(propType, /*isProperty*/ true) : + symbol.links.checkFlags & CheckFlags.StripOptional ? removeMissingOrUndefinedType(propType) : + propType; + if (!popTypeResolution()) { + error(currentNode, Diagnostics.Type_of_property_0_circularly_references_itself_in_mapped_type_1, symbolToString(symbol), typeToString(mappedType)); + type = errorType; + } + symbol.links.type ??= type; + } + return symbol.links.type; + } + + function getTypeParameterFromMappedType(type: MappedType) { + return type.typeParameter || + (type.typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(type.declaration.typeParameter))); + } + + function getConstraintTypeFromMappedType(type: MappedType) { + return type.constraintType || + (type.constraintType = getConstraintOfTypeParameter(getTypeParameterFromMappedType(type)) || errorType); + } + + function getNameTypeFromMappedType(type: MappedType) { + return type.declaration.nameType ? + type.nameType || (type.nameType = instantiateType(getTypeFromTypeNode(type.declaration.nameType), type.mapper)) : + undefined; + } + + function getTemplateTypeFromMappedType(type: MappedType) { + return type.templateType || + (type.templateType = type.declaration.type ? + instantiateType(addOptionality(getTypeFromTypeNode(type.declaration.type), /*isProperty*/ true, !!(getMappedTypeModifiers(type) & MappedTypeModifiers.IncludeOptional)), type.mapper) : + errorType); + } + + function getConstraintDeclarationForMappedType(type: MappedType) { + return getEffectiveConstraintOfTypeParameter(type.declaration.typeParameter); + } + + function isMappedTypeWithKeyofConstraintDeclaration(type: MappedType) { + const constraintDeclaration = getConstraintDeclarationForMappedType(type)!; // TODO: GH#18217 + return constraintDeclaration.kind === SyntaxKind.TypeOperator && + (constraintDeclaration as TypeOperatorNode).operator === SyntaxKind.KeyOfKeyword; + } + + function getModifiersTypeFromMappedType(type: MappedType) { + if (!type.modifiersType) { + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // If the constraint declaration is a 'keyof T' node, the modifiers type is T. We check + // AST nodes here because, when T is a non-generic type, the logic below eagerly resolves + // 'keyof T' to a literal union type and we can't recover T from that type. + type.modifiersType = instantiateType(getTypeFromTypeNode((getConstraintDeclarationForMappedType(type) as TypeOperatorNode).type), type.mapper); + } + else { + // Otherwise, get the declared constraint type, and if the constraint type is a type parameter, + // get the constraint of that type parameter. If the resulting type is an indexed type 'keyof T', + // the modifiers type is T. Otherwise, the modifiers type is unknown. + const declaredType = getTypeFromMappedTypeNode(type.declaration) as MappedType; + const constraint = getConstraintTypeFromMappedType(declaredType); + const extendedConstraint = constraint && constraint.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(constraint as TypeParameter) : constraint; + type.modifiersType = extendedConstraint && extendedConstraint.flags & TypeFlags.Index ? instantiateType((extendedConstraint as IndexType).type, type.mapper) : unknownType; + } + } + return type.modifiersType; + } + + function getMappedTypeModifiers(type: MappedType): MappedTypeModifiers { + const declaration = type.declaration; + return (declaration.readonlyToken ? declaration.readonlyToken.kind === SyntaxKind.MinusToken ? MappedTypeModifiers.ExcludeReadonly : MappedTypeModifiers.IncludeReadonly : 0) | + (declaration.questionToken ? declaration.questionToken.kind === SyntaxKind.MinusToken ? MappedTypeModifiers.ExcludeOptional : MappedTypeModifiers.IncludeOptional : 0); + } + + // Return -1, 0, or 1, where -1 means optionality is stripped (i.e. -?), 0 means optionality is unchanged, and 1 means + // optionality is added (i.e. +?). + function getMappedTypeOptionality(type: MappedType): number { + const modifiers = getMappedTypeModifiers(type); + return modifiers & MappedTypeModifiers.ExcludeOptional ? -1 : modifiers & MappedTypeModifiers.IncludeOptional ? 1 : 0; + } + + // Return -1, 0, or 1, for stripped, unchanged, or added optionality respectively. When a homomorphic mapped type doesn't + // modify optionality, recursively consult the optionality of the type being mapped over to see if it strips or adds optionality. + // For intersections, return -1 or 1 when all constituents strip or add optionality, otherwise return 0. + function getCombinedMappedTypeOptionality(type: Type): number { + if (getObjectFlags(type) & ObjectFlags.Mapped) { + return getMappedTypeOptionality(type as MappedType) || getCombinedMappedTypeOptionality(getModifiersTypeFromMappedType(type as MappedType)); + } + if (type.flags & TypeFlags.Intersection) { + const optionality = getCombinedMappedTypeOptionality((type as IntersectionType).types[0]); + return every((type as IntersectionType).types, (t, i) => i === 0 || getCombinedMappedTypeOptionality(t) === optionality) ? optionality : 0; + } + return 0; + } + + function isPartialMappedType(type: Type) { + return !!(getObjectFlags(type) & ObjectFlags.Mapped && getMappedTypeModifiers(type as MappedType) & MappedTypeModifiers.IncludeOptional); + } + + function isGenericMappedType(type: Type): type is MappedType { + if (getObjectFlags(type) & ObjectFlags.Mapped) { + const constraint = getConstraintTypeFromMappedType(type as MappedType); + if (isGenericIndexType(constraint)) { + return true; + } + // A mapped type is generic if the 'as' clause references generic types other than the iteration type. + // To determine this, we substitute the constraint type (that we now know isn't generic) for the iteration + // type and check whether the resulting type is generic. + const nameType = getNameTypeFromMappedType(type as MappedType); + if (nameType && isGenericIndexType(instantiateType(nameType, makeUnaryTypeMapper(getTypeParameterFromMappedType(type as MappedType), constraint)))) { + return true; + } + } + return false; + } + + function getMappedTypeNameTypeKind(type: MappedType): MappedTypeNameTypeKind { + const nameType = getNameTypeFromMappedType(type); + if (!nameType) { + return MappedTypeNameTypeKind.None; + } + return isTypeAssignableTo(nameType, getTypeParameterFromMappedType(type)) ? MappedTypeNameTypeKind.Filtering : MappedTypeNameTypeKind.Remapping; + } + + function resolveStructuredTypeMembers(type: StructuredType): ResolvedType { + if (!(type as ResolvedType).members) { + if (type.flags & TypeFlags.Object) { + if ((type as ObjectType).objectFlags & ObjectFlags.Reference) { + resolveTypeReferenceMembers(type as TypeReference); + } + else if ((type as ObjectType).objectFlags & ObjectFlags.ClassOrInterface) { + resolveClassOrInterfaceMembers(type as InterfaceType); + } + else if ((type as ReverseMappedType).objectFlags & ObjectFlags.ReverseMapped) { + resolveReverseMappedTypeMembers(type as ReverseMappedType); + } + else if ((type as ObjectType).objectFlags & ObjectFlags.Anonymous) { + resolveAnonymousTypeMembers(type as AnonymousType); + } + else if ((type as MappedType).objectFlags & ObjectFlags.Mapped) { + resolveMappedTypeMembers(type as MappedType); + } + else { + Debug.fail("Unhandled object type " + Debug.formatObjectFlags(type.objectFlags)); + } + } + else if (type.flags & TypeFlags.Union) { + resolveUnionTypeMembers(type as UnionType); + } + else if (type.flags & TypeFlags.Intersection) { + resolveIntersectionTypeMembers(type as IntersectionType); + } + else { + Debug.fail("Unhandled type " + Debug.formatTypeFlags(type.flags)); + } + } + return type as ResolvedType; + } + + /** Return properties of an object type or an empty array for other types */ + function getPropertiesOfObjectType(type: Type): Symbol[] { + if (type.flags & TypeFlags.Object) { + return resolveStructuredTypeMembers(type as ObjectType).properties; + } + return emptyArray; + } + + /** If the given type is an object type and that type has a property by the given name, + * return the symbol for that property. Otherwise return undefined. + */ + function getPropertyOfObjectType(type: Type, name: __String): Symbol | undefined { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + const symbol = resolved.members.get(name); + if (symbol && symbolIsValue(symbol)) { + return symbol; + } + } + } + + function getPropertiesOfUnionOrIntersectionType(type: UnionOrIntersectionType): Symbol[] { + if (!type.resolvedProperties) { + const members = createSymbolTable(); + for (const current of type.types) { + for (const prop of getPropertiesOfType(current)) { + if (!members.has(prop.escapedName)) { + const combinedProp = getPropertyOfUnionOrIntersectionType(type, prop.escapedName, /*skipObjectFunctionPropertyAugment*/ !!(type.flags & TypeFlags.Intersection)); + if (combinedProp) { + members.set(prop.escapedName, combinedProp); + } + } + } + // The properties of a union type are those that are present in all constituent types, so + // we only need to check the properties of the first type without index signature + if (type.flags & TypeFlags.Union && getIndexInfosOfType(current).length === 0) { + break; + } + } + type.resolvedProperties = getNamedMembers(members); + } + return type.resolvedProperties; + } + + function getPropertiesOfType(type: Type): Symbol[] { + type = getReducedApparentType(type); + return type.flags & TypeFlags.UnionOrIntersection ? + getPropertiesOfUnionOrIntersectionType(type as UnionType) : + getPropertiesOfObjectType(type); + } + + function forEachPropertyOfType(type: Type, action: (symbol: Symbol, escapedName: __String) => void): void { + type = getReducedApparentType(type); + if (type.flags & TypeFlags.StructuredType) { + resolveStructuredTypeMembers(type as StructuredType).members.forEach((symbol, escapedName) => { + if (isNamedMember(symbol, escapedName)) { + action(symbol, escapedName); + } + }); + } + } + + function isTypeInvalidDueToUnionDiscriminant(contextualType: Type, obj: ObjectLiteralExpression | JsxAttributes): boolean { + const list = obj.properties as NodeArray; + return list.some(property => { + const nameType = property.name && (isJsxNamespacedName(property.name) ? getStringLiteralType(getTextOfJsxAttributeName(property.name)) : getLiteralTypeFromPropertyName(property.name)); + const name = nameType && isTypeUsableAsPropertyName(nameType) ? getPropertyNameFromType(nameType) : undefined; + const expected = name === undefined ? undefined : getTypeOfPropertyOfType(contextualType, name); + return !!expected && isLiteralType(expected) && !isTypeAssignableTo(getTypeOfNode(property), expected); + }); + } + + function getAllPossiblePropertiesOfTypes(types: readonly Type[]): Symbol[] { + const unionType = getUnionType(types); + if (!(unionType.flags & TypeFlags.Union)) { + return getAugmentedPropertiesOfType(unionType); + } + + const props = createSymbolTable(); + for (const memberType of types) { + for (const { escapedName } of getAugmentedPropertiesOfType(memberType)) { + if (!props.has(escapedName)) { + const prop = createUnionOrIntersectionProperty(unionType as UnionType, escapedName); + // May be undefined if the property is private + if (prop) props.set(escapedName, prop); + } + } + } + return arrayFrom(props.values()); + } + + function getConstraintOfType(type: InstantiableType | UnionOrIntersectionType): Type | undefined { + return type.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(type as TypeParameter) : + type.flags & TypeFlags.IndexedAccess ? getConstraintOfIndexedAccess(type as IndexedAccessType) : + type.flags & TypeFlags.Conditional ? getConstraintOfConditionalType(type as ConditionalType) : + getBaseConstraintOfType(type); + } + + function getConstraintOfTypeParameter(typeParameter: TypeParameter): Type | undefined { + return hasNonCircularBaseConstraint(typeParameter) ? getConstraintFromTypeParameter(typeParameter) : undefined; + } + + function isConstMappedType(type: MappedType, depth: number): boolean { + const typeVariable = getHomomorphicTypeVariable(type); + return !!typeVariable && isConstTypeVariable(typeVariable, depth); + } + + function isConstTypeVariable(type: Type | undefined, depth = 0): boolean { + return depth < 5 && !!(type && ( + type.flags & TypeFlags.TypeParameter && some((type as TypeParameter).symbol?.declarations, d => hasSyntacticModifier(d, ModifierFlags.Const)) || + type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, t => isConstTypeVariable(t, depth)) || + type.flags & TypeFlags.IndexedAccess && isConstTypeVariable((type as IndexedAccessType).objectType, depth + 1) || + type.flags & TypeFlags.Conditional && isConstTypeVariable(getConstraintOfConditionalType(type as ConditionalType), depth + 1) || + type.flags & TypeFlags.Substitution && isConstTypeVariable((type as SubstitutionType).baseType, depth) || + getObjectFlags(type) & ObjectFlags.Mapped && isConstMappedType(type as MappedType, depth) || + isGenericTupleType(type) && findIndex(getElementTypes(type), (t, i) => !!(type.target.elementFlags[i] & ElementFlags.Variadic) && isConstTypeVariable(t, depth)) >= 0 + )); + } + + function getConstraintOfIndexedAccess(type: IndexedAccessType) { + return hasNonCircularBaseConstraint(type) ? getConstraintFromIndexedAccess(type) : undefined; + } + + function getSimplifiedTypeOrConstraint(type: Type) { + const simplified = getSimplifiedType(type, /*writing*/ false); + return simplified !== type ? simplified : getConstraintOfType(type); + } + + function getConstraintFromIndexedAccess(type: IndexedAccessType) { + if (isMappedTypeGenericIndexedAccess(type)) { + // For indexed access types of the form { [P in K]: E }[X], where K is non-generic and X is generic, + // we substitute an instantiation of E where P is replaced with X. + return substituteIndexedMappedType(type.objectType as MappedType, type.indexType); + } + const indexConstraint = getSimplifiedTypeOrConstraint(type.indexType); + if (indexConstraint && indexConstraint !== type.indexType) { + const indexedAccess = getIndexedAccessTypeOrUndefined(type.objectType, indexConstraint, type.accessFlags); + if (indexedAccess) { + return indexedAccess; + } + } + const objectConstraint = getSimplifiedTypeOrConstraint(type.objectType); + if (objectConstraint && objectConstraint !== type.objectType) { + return getIndexedAccessTypeOrUndefined(objectConstraint, type.indexType, type.accessFlags); + } + return undefined; + } + + function getDefaultConstraintOfConditionalType(type: ConditionalType) { + if (!type.resolvedDefaultConstraint) { + // An `any` branch of a conditional type would normally be viral - specifically, without special handling here, + // a conditional type with a single branch of type `any` would be assignable to anything, since it's constraint would simplify to + // just `any`. This result is _usually_ unwanted - so instead here we elide an `any` branch from the constraint type, + // in effect treating `any` like `never` rather than `unknown` in this location. + const trueConstraint = getInferredTrueTypeFromConditionalType(type); + const falseConstraint = getFalseTypeFromConditionalType(type); + type.resolvedDefaultConstraint = isTypeAny(trueConstraint) ? falseConstraint : isTypeAny(falseConstraint) ? trueConstraint : getUnionType([trueConstraint, falseConstraint]); + } + return type.resolvedDefaultConstraint; + } + + function getConstraintOfDistributiveConditionalType(type: ConditionalType): Type | undefined { + if (type.resolvedConstraintOfDistributive !== undefined) { + return type.resolvedConstraintOfDistributive || undefined; + } + + // Check if we have a conditional type of the form 'T extends U ? X : Y', where T is a constrained + // type parameter. If so, create an instantiation of the conditional type where T is replaced + // with its constraint. We do this because if the constraint is a union type it will be distributed + // over the conditional type and possibly reduced. For example, 'T extends undefined ? never : T' + // removes 'undefined' from T. + // We skip returning a distributive constraint for a restrictive instantiation of a conditional type + // as the constraint for all type params (check type included) have been replace with `unknown`, which + // is going to produce even more false positive/negative results than the distribute constraint already does. + // Please note: the distributive constraint is a kludge for emulating what a negated type could to do filter + // a union - once negated types exist and are applied to the conditional false branch, this "constraint" + // likely doesn't need to exist. + if (type.root.isDistributive && type.restrictiveInstantiation !== type) { + const simplified = getSimplifiedType(type.checkType, /*writing*/ false); + const constraint = simplified === type.checkType ? getConstraintOfType(simplified) : simplified; + if (constraint && constraint !== type.checkType) { + const instantiated = getConditionalTypeInstantiation(type, prependTypeMapping(type.root.checkType, constraint, type.mapper), /*forConstraint*/ true); + if (!(instantiated.flags & TypeFlags.Never)) { + type.resolvedConstraintOfDistributive = instantiated; + return instantiated; + } + } + } + type.resolvedConstraintOfDistributive = false; + return undefined; + } + + function getConstraintFromConditionalType(type: ConditionalType) { + return getConstraintOfDistributiveConditionalType(type) || getDefaultConstraintOfConditionalType(type); + } + + function getConstraintOfConditionalType(type: ConditionalType) { + return hasNonCircularBaseConstraint(type) ? getConstraintFromConditionalType(type) : undefined; + } + + function getEffectiveConstraintOfIntersection(types: readonly Type[], targetIsUnion: boolean) { + let constraints: Type[] | undefined; + let hasDisjointDomainType = false; + for (const t of types) { + if (t.flags & TypeFlags.Instantiable) { + // We keep following constraints as long as we have an instantiable type that is known + // not to be circular or infinite (hence we stop on index access types). + let constraint = getConstraintOfType(t); + while (constraint && constraint.flags & (TypeFlags.TypeParameter | TypeFlags.Index | TypeFlags.Conditional)) { + constraint = getConstraintOfType(constraint); + } + if (constraint) { + constraints = append(constraints, constraint); + if (targetIsUnion) { + constraints = append(constraints, t); + } + } + } + else if (t.flags & TypeFlags.DisjointDomains || isEmptyAnonymousObjectType(t)) { + hasDisjointDomainType = true; + } + } + // If the target is a union type or if we are intersecting with types belonging to one of the + // disjoint domains, we may end up producing a constraint that hasn't been examined before. + if (constraints && (targetIsUnion || hasDisjointDomainType)) { + if (hasDisjointDomainType) { + // We add any types belong to one of the disjoint domains because they might cause the final + // intersection operation to reduce the union constraints. + for (const t of types) { + if (t.flags & TypeFlags.DisjointDomains || isEmptyAnonymousObjectType(t)) { + constraints = append(constraints, t); + } + } + } + // The source types were normalized; ensure the result is normalized too. + return getNormalizedType(getIntersectionType(constraints, IntersectionFlags.NoConstraintReduction), /*writing*/ false); + } + return undefined; + } + + function getBaseConstraintOfType(type: Type): Type | undefined { + if (type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.UnionOrIntersection | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || isGenericTupleType(type)) { + const constraint = getResolvedBaseConstraint(type as InstantiableType | UnionOrIntersectionType); + return constraint !== noConstraintType && constraint !== circularConstraintType ? constraint : undefined; + } + return type.flags & TypeFlags.Index ? stringNumberSymbolType : undefined; + } + + /** + * This is similar to `getBaseConstraintOfType` except it returns the input type if there's no base constraint, instead of `undefined` + * It also doesn't map indexes to `string`, as where this is used this would be unneeded (and likely undesirable) + */ + function getBaseConstraintOrType(type: Type) { + return getBaseConstraintOfType(type) || type; + } + + function hasNonCircularBaseConstraint(type: InstantiableType): boolean { + return getResolvedBaseConstraint(type) !== circularConstraintType; + } + + /** + * Return the resolved base constraint of a type variable. The noConstraintType singleton is returned if the + * type variable has no constraint, and the circularConstraintType singleton is returned if the constraint + * circularly references the type variable. + */ + function getResolvedBaseConstraint(type: InstantiableType | UnionOrIntersectionType): Type { + if (type.resolvedBaseConstraint) { + return type.resolvedBaseConstraint; + } + const stack: object[] = []; + return type.resolvedBaseConstraint = getImmediateBaseConstraint(type); + + function getImmediateBaseConstraint(t: Type): Type { + if (!t.immediateBaseConstraint) { + if (!pushTypeResolution(t, TypeSystemPropertyName.ImmediateBaseConstraint)) { + return circularConstraintType; + } + let result; + // We always explore at least 10 levels of nested constraints. Thereafter, we continue to explore + // up to 50 levels of nested constraints provided there are no "deeply nested" types on the stack + // (i.e. no types for which five instantiations have been recorded on the stack). If we reach 50 + // levels of nesting, we are presumably exploring a repeating pattern with a long cycle that hasn't + // yet triggered the deeply nested limiter. We have no test cases that actually get to 50 levels of + // nesting, so it is effectively just a safety stop. + const identity = getRecursionIdentity(t); + if (stack.length < 10 || stack.length < 50 && !contains(stack, identity)) { + stack.push(identity); + result = computeBaseConstraint(getSimplifiedType(t, /*writing*/ false)); + stack.pop(); + } + if (!popTypeResolution()) { + if (t.flags & TypeFlags.TypeParameter) { + const errorNode = getConstraintDeclaration(t as TypeParameter); + if (errorNode) { + const diagnostic = error(errorNode, Diagnostics.Type_parameter_0_has_a_circular_constraint, typeToString(t)); + if (currentNode && !isNodeDescendantOf(errorNode, currentNode) && !isNodeDescendantOf(currentNode, errorNode)) { + addRelatedInfo(diagnostic, createDiagnosticForNode(currentNode, Diagnostics.Circularity_originates_in_type_at_this_location)); + } + } + } + result = circularConstraintType; + } + t.immediateBaseConstraint ??= result || noConstraintType; + } + return t.immediateBaseConstraint; + } + + function getBaseConstraint(t: Type): Type | undefined { + const c = getImmediateBaseConstraint(t); + return c !== noConstraintType && c !== circularConstraintType ? c : undefined; + } + + function computeBaseConstraint(t: Type): Type | undefined { + if (t.flags & TypeFlags.TypeParameter) { + const constraint = getConstraintFromTypeParameter(t as TypeParameter); + return (t as TypeParameter).isThisType || !constraint ? + constraint : + getBaseConstraint(constraint); + } + if (t.flags & TypeFlags.UnionOrIntersection) { + const types = (t as UnionOrIntersectionType).types; + const baseTypes: Type[] = []; + let different = false; + for (const type of types) { + const baseType = getBaseConstraint(type); + if (baseType) { + if (baseType !== type) { + different = true; + } + baseTypes.push(baseType); + } + else { + different = true; + } + } + if (!different) { + return t; + } + return t.flags & TypeFlags.Union && baseTypes.length === types.length ? getUnionType(baseTypes) : + t.flags & TypeFlags.Intersection && baseTypes.length ? getIntersectionType(baseTypes) : + undefined; + } + if (t.flags & TypeFlags.Index) { + return stringNumberSymbolType; + } + if (t.flags & TypeFlags.TemplateLiteral) { + const types = (t as TemplateLiteralType).types; + const constraints = mapDefined(types, getBaseConstraint); + return constraints.length === types.length ? getTemplateLiteralType((t as TemplateLiteralType).texts, constraints) : stringType; + } + if (t.flags & TypeFlags.StringMapping) { + const constraint = getBaseConstraint((t as StringMappingType).type); + return constraint && constraint !== (t as StringMappingType).type ? getStringMappingType((t as StringMappingType).symbol, constraint) : stringType; + } + if (t.flags & TypeFlags.IndexedAccess) { + if (isMappedTypeGenericIndexedAccess(t)) { + // For indexed access types of the form { [P in K]: E }[X], where K is non-generic and X is generic, + // we substitute an instantiation of E where P is replaced with X. + return getBaseConstraint(substituteIndexedMappedType((t as IndexedAccessType).objectType as MappedType, (t as IndexedAccessType).indexType)); + } + const baseObjectType = getBaseConstraint((t as IndexedAccessType).objectType); + const baseIndexType = getBaseConstraint((t as IndexedAccessType).indexType); + const baseIndexedAccess = baseObjectType && baseIndexType && getIndexedAccessTypeOrUndefined(baseObjectType, baseIndexType, (t as IndexedAccessType).accessFlags); + return baseIndexedAccess && getBaseConstraint(baseIndexedAccess); + } + if (t.flags & TypeFlags.Conditional) { + const constraint = getConstraintFromConditionalType(t as ConditionalType); + return constraint && getBaseConstraint(constraint); + } + if (t.flags & TypeFlags.Substitution) { + return getBaseConstraint(getSubstitutionIntersection(t as SubstitutionType)); + } + if (isGenericTupleType(t)) { + // We substitute constraints for variadic elements only when the constraints are array types or + // non-variadic tuple types as we want to avoid further (possibly unbounded) recursion. + const newElements = map(getElementTypes(t), (v, i) => { + const constraint = v.flags & TypeFlags.TypeParameter && t.target.elementFlags[i] & ElementFlags.Variadic && getBaseConstraint(v) || v; + return constraint !== v && everyType(constraint, c => isArrayOrTupleType(c) && !isGenericTupleType(c)) ? constraint : v; + }); + return createTupleType(newElements, t.target.elementFlags, t.target.readonly, t.target.labeledElementDeclarations); + } + return t; + } + } + + function getApparentTypeOfIntersectionType(type: IntersectionType, thisArgument: Type) { + if (type === thisArgument) { + return type.resolvedApparentType || (type.resolvedApparentType = getTypeWithThisArgument(type, thisArgument, /*needApparentType*/ true)); + } + const key = `I${getTypeId(type)},${getTypeId(thisArgument)}`; + return getCachedType(key) ?? setCachedType(key, getTypeWithThisArgument(type, thisArgument, /*needApparentType*/ true)); + } + + function getResolvedTypeParameterDefault(typeParameter: TypeParameter): Type | undefined { + if (!typeParameter.default) { + if (typeParameter.target) { + const targetDefault = getResolvedTypeParameterDefault(typeParameter.target); + typeParameter.default = targetDefault ? instantiateType(targetDefault, typeParameter.mapper) : noConstraintType; + } + else { + // To block recursion, set the initial value to the resolvingDefaultType. + typeParameter.default = resolvingDefaultType; + const defaultDeclaration = typeParameter.symbol && forEach(typeParameter.symbol.declarations, decl => isTypeParameterDeclaration(decl) && decl.default); + const defaultType = defaultDeclaration ? getTypeFromTypeNode(defaultDeclaration) : noConstraintType; + if (typeParameter.default === resolvingDefaultType) { + // If we have not been called recursively, set the correct default type. + typeParameter.default = defaultType; + } + } + } + else if (typeParameter.default === resolvingDefaultType) { + // If we are called recursively for this type parameter, mark the default as circular. + typeParameter.default = circularConstraintType; + } + return typeParameter.default; + } + + /** + * Gets the default type for a type parameter. + * + * If the type parameter is the result of an instantiation, this gets the instantiated + * default type of its target. If the type parameter has no default type or the default is + * circular, `undefined` is returned. + */ + function getDefaultFromTypeParameter(typeParameter: TypeParameter): Type | undefined { + const defaultType = getResolvedTypeParameterDefault(typeParameter); + return defaultType !== noConstraintType && defaultType !== circularConstraintType ? defaultType : undefined; + } + + function hasNonCircularTypeParameterDefault(typeParameter: TypeParameter) { + return getResolvedTypeParameterDefault(typeParameter) !== circularConstraintType; + } + + /** + * Indicates whether the declaration of a typeParameter has a default type. + */ + function hasTypeParameterDefault(typeParameter: TypeParameter): boolean { + return !!(typeParameter.symbol && forEach(typeParameter.symbol.declarations, decl => isTypeParameterDeclaration(decl) && decl.default)); + } + + function getApparentTypeOfMappedType(type: MappedType) { + return type.resolvedApparentType || (type.resolvedApparentType = getResolvedApparentTypeOfMappedType(type)); + } + + function getResolvedApparentTypeOfMappedType(type: MappedType): Type { + const target = (type.target ?? type) as MappedType; + const typeVariable = getHomomorphicTypeVariable(target); + if (typeVariable && !target.declaration.nameType) { + // We have a homomorphic mapped type or an instantiation of a homomorphic mapped type, i.e. a type + // of the form { [P in keyof T]: X }. Obtain the modifiers type (the T of the keyof T), and if it is + // another generic mapped type, recursively obtain its apparent type. Otherwise, obtain its base + // constraint. Then, if every constituent of the base constraint is an array or tuple type, apply + // this mapped type to the base constraint. It is safe to recurse when the modifiers type is a + // mapped type because we protect again circular constraints in getTypeFromMappedTypeNode. + const modifiersType = getModifiersTypeFromMappedType(type); + const baseConstraint = isGenericMappedType(modifiersType) ? getApparentTypeOfMappedType(modifiersType) : getBaseConstraintOfType(modifiersType); + if (baseConstraint && everyType(baseConstraint, t => isArrayOrTupleType(t) || isArrayOrTupleOrIntersection(t))) { + return instantiateType(target, prependTypeMapping(typeVariable, baseConstraint, type.mapper)); + } + } + return type; + } + + function isArrayOrTupleOrIntersection(type: Type) { + return !!(type.flags & TypeFlags.Intersection) && every((type as IntersectionType).types, isArrayOrTupleType); + } + + function isMappedTypeGenericIndexedAccess(type: Type) { + let objectType; + return !!(type.flags & TypeFlags.IndexedAccess && getObjectFlags(objectType = (type as IndexedAccessType).objectType) & ObjectFlags.Mapped && + !isGenericMappedType(objectType) && isGenericIndexType((type as IndexedAccessType).indexType) && + !(getMappedTypeModifiers(objectType as MappedType) & MappedTypeModifiers.ExcludeOptional) && !(objectType as MappedType).declaration.nameType); + } + + /** + * For a type parameter, return the base constraint of the type parameter. For the string, number, + * boolean, and symbol primitive types, return the corresponding object types. Otherwise return the + * type itself. + */ + function getApparentType(type: Type): Type { + const t = type.flags & TypeFlags.Instantiable ? getBaseConstraintOfType(type) || unknownType : type; + const objectFlags = getObjectFlags(t); + return objectFlags & ObjectFlags.Mapped ? getApparentTypeOfMappedType(t as MappedType) : + objectFlags & ObjectFlags.Reference && t !== type ? getTypeWithThisArgument(t, type) : + t.flags & TypeFlags.Intersection ? getApparentTypeOfIntersectionType(t as IntersectionType, type) : + t.flags & TypeFlags.StringLike ? globalStringType : + t.flags & TypeFlags.NumberLike ? globalNumberType : + t.flags & TypeFlags.BigIntLike ? getGlobalBigIntType() : + t.flags & TypeFlags.BooleanLike ? globalBooleanType : + t.flags & TypeFlags.ESSymbolLike ? getGlobalESSymbolType() : + t.flags & TypeFlags.NonPrimitive ? emptyObjectType : + t.flags & TypeFlags.Index ? stringNumberSymbolType : + t.flags & TypeFlags.Unknown && !strictNullChecks ? emptyObjectType : + t; + } + + function getReducedApparentType(type: Type): Type { + // Since getApparentType may return a non-reduced union or intersection type, we need to perform + // type reduction both before and after obtaining the apparent type. For example, given a type parameter + // 'T extends A | B', the type 'T & X' becomes 'A & X | B & X' after obtaining the apparent type, and + // that type may need further reduction to remove empty intersections. + return getReducedType(getApparentType(getReducedType(type))); + } + + function createUnionOrIntersectionProperty(containingType: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { + let singleProp: Symbol | undefined; + let propSet: Map | undefined; + let indexTypes: Type[] | undefined; + const isUnion = containingType.flags & TypeFlags.Union; + // Flags we want to propagate to the result if they exist in all source symbols + let optionalFlag: SymbolFlags | undefined; + let syntheticFlag = CheckFlags.SyntheticMethod; + let checkFlags = isUnion ? 0 : CheckFlags.Readonly; + let mergedInstantiations = false; + for (const current of containingType.types) { + const type = getApparentType(current); + if (!(isErrorType(type) || type.flags & TypeFlags.Never)) { + const prop = getPropertyOfType(type, name, skipObjectFunctionPropertyAugment); + const modifiers = prop ? getDeclarationModifierFlagsFromSymbol(prop) : 0; + if (prop) { + if (prop.flags & SymbolFlags.ClassMember) { + optionalFlag ??= isUnion ? SymbolFlags.None : SymbolFlags.Optional; + if (isUnion) { + optionalFlag |= prop.flags & SymbolFlags.Optional; + } + else { + optionalFlag &= prop.flags; + } + } + if (!singleProp) { + singleProp = prop; + } + else if (prop !== singleProp) { + const isInstantiation = (getTargetSymbol(prop) || prop) === (getTargetSymbol(singleProp) || singleProp); + // If the symbols are instances of one another with identical types - consider the symbols + // equivalent and just use the first one, which thus allows us to avoid eliding private + // members when intersecting a (this-)instantiations of a class with its raw base or another instance + if (isInstantiation && compareProperties(singleProp, prop, (a, b) => a === b ? Ternary.True : Ternary.False) === Ternary.True) { + // If we merged instantiations of a generic type, we replicate the symbol parent resetting behavior we used + // to do when we recorded multiple distinct symbols so that we still get, eg, `Array.length` printed + // back and not `Array.length` when we're looking at a `.length` access on a `string[] | number[]` + mergedInstantiations = !!singleProp.parent && !!length(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(singleProp.parent)); + } + else { + if (!propSet) { + propSet = new Map(); + propSet.set(getSymbolId(singleProp), singleProp); + } + const id = getSymbolId(prop); + if (!propSet.has(id)) { + propSet.set(id, prop); + } + } + } + if (isUnion && isReadonlySymbol(prop)) { + checkFlags |= CheckFlags.Readonly; + } + else if (!isUnion && !isReadonlySymbol(prop)) { + checkFlags &= ~CheckFlags.Readonly; + } + checkFlags |= (!(modifiers & ModifierFlags.NonPublicAccessibilityModifier) ? CheckFlags.ContainsPublic : 0) | + (modifiers & ModifierFlags.Protected ? CheckFlags.ContainsProtected : 0) | + (modifiers & ModifierFlags.Private ? CheckFlags.ContainsPrivate : 0) | + (modifiers & ModifierFlags.Static ? CheckFlags.ContainsStatic : 0); + if (!isPrototypeProperty(prop)) { + syntheticFlag = CheckFlags.SyntheticProperty; + } + } + else if (isUnion) { + const indexInfo = !isLateBoundName(name) && getApplicableIndexInfoForName(type, name); + if (indexInfo) { + checkFlags |= CheckFlags.WritePartial | (indexInfo.isReadonly ? CheckFlags.Readonly : 0); + indexTypes = append(indexTypes, isTupleType(type) ? getRestTypeOfTupleType(type) || undefinedType : indexInfo.type); + } + else if (isObjectLiteralType(type) && !(getObjectFlags(type) & ObjectFlags.ContainsSpread)) { + checkFlags |= CheckFlags.WritePartial; + indexTypes = append(indexTypes, undefinedType); + } + else { + checkFlags |= CheckFlags.ReadPartial; + } + } + } + } + if ( + !singleProp || + isUnion && + (propSet || checkFlags & CheckFlags.Partial) && + checkFlags & (CheckFlags.ContainsPrivate | CheckFlags.ContainsProtected) && + !(propSet && getCommonDeclarationsOfSymbols(propSet.values())) + ) { + // No property was found, or, in a union, a property has a private or protected declaration in one + // constituent, but is missing or has a different declaration in another constituent. + return undefined; + } + if (!propSet && !(checkFlags & CheckFlags.ReadPartial) && !indexTypes) { + if (mergedInstantiations) { + // No symbol from a union/intersection should have a `.parent` set (since unions/intersections don't act as symbol parents) + // Unless that parent is "reconstituted" from the "first value declaration" on the symbol (which is likely different than its instantiated parent!) + // They also have a `.containingType` set, which affects some services endpoints behavior, like `getRootSymbol` + const links = tryCast(singleProp, isTransientSymbol)?.links; + const clone = createSymbolWithType(singleProp, links?.type); + clone.parent = singleProp.valueDeclaration?.symbol?.parent; + clone.links.containingType = containingType; + clone.links.mapper = links?.mapper; + clone.links.writeType = getWriteTypeOfSymbol(singleProp); + return clone; + } + else { + return singleProp; + } + } + const props = propSet ? arrayFrom(propSet.values()) : [singleProp]; + let declarations: Declaration[] | undefined; + let firstType: Type | undefined; + let nameType: Type | undefined; + const propTypes: Type[] = []; + let writeTypes: Type[] | undefined; + let firstValueDeclaration: Declaration | undefined; + let hasNonUniformValueDeclaration = false; + for (const prop of props) { + if (!firstValueDeclaration) { + firstValueDeclaration = prop.valueDeclaration; + } + else if (prop.valueDeclaration && prop.valueDeclaration !== firstValueDeclaration) { + hasNonUniformValueDeclaration = true; + } + declarations = addRange(declarations, prop.declarations); + const type = getTypeOfSymbol(prop); + if (!firstType) { + firstType = type; + nameType = getSymbolLinks(prop).nameType; + } + const writeType = getWriteTypeOfSymbol(prop); + if (writeTypes || writeType !== type) { + writeTypes = append(!writeTypes ? propTypes.slice() : writeTypes, writeType); + } + if (type !== firstType) { + checkFlags |= CheckFlags.HasNonUniformType; + } + if (isLiteralType(type) || isPatternLiteralType(type)) { + checkFlags |= CheckFlags.HasLiteralType; + } + if (type.flags & TypeFlags.Never && type !== uniqueLiteralType) { + checkFlags |= CheckFlags.HasNeverType; + } + propTypes.push(type); + } + addRange(propTypes, indexTypes); + const result = createSymbol(SymbolFlags.Property | (optionalFlag ?? 0), name, syntheticFlag | checkFlags); + result.links.containingType = containingType; + if (!hasNonUniformValueDeclaration && firstValueDeclaration) { + result.valueDeclaration = firstValueDeclaration; + + // Inherit information about parent type. + if (firstValueDeclaration.symbol.parent) { + result.parent = firstValueDeclaration.symbol.parent; + } + } + + result.declarations = declarations; + result.links.nameType = nameType; + if (propTypes.length > 2) { + // When `propTypes` has the potential to explode in size when normalized, defer normalization until absolutely needed + result.links.checkFlags |= CheckFlags.DeferredType; + result.links.deferralParent = containingType; + result.links.deferralConstituents = propTypes; + result.links.deferralWriteConstituents = writeTypes; + } + else { + result.links.type = isUnion ? getUnionType(propTypes) : getIntersectionType(propTypes); + if (writeTypes) { + result.links.writeType = isUnion ? getUnionType(writeTypes) : getIntersectionType(writeTypes); + } + } + return result; + } + + // Return the symbol for a given property in a union or intersection type, or undefined if the property + // does not exist in any constituent type. Note that the returned property may only be present in some + // constituents, in which case the isPartial flag is set when the containing type is union type. We need + // these partial properties when identifying discriminant properties, but otherwise they are filtered out + // and do not appear to be present in the union type. + function getUnionOrIntersectionProperty(type: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { + let property = skipObjectFunctionPropertyAugment ? + type.propertyCacheWithoutObjectFunctionPropertyAugment?.get(name) : + type.propertyCache?.get(name); + if (!property) { + property = createUnionOrIntersectionProperty(type, name, skipObjectFunctionPropertyAugment); + if (property) { + const properties = skipObjectFunctionPropertyAugment ? + type.propertyCacheWithoutObjectFunctionPropertyAugment ||= createSymbolTable() : + type.propertyCache ||= createSymbolTable(); + properties.set(name, property); + // Propagate an entry from the non-augmented cache to the augmented cache unless the property is partial. + if (skipObjectFunctionPropertyAugment && !(getCheckFlags(property) & CheckFlags.Partial) && !type.propertyCache?.get(name)) { + const properties = type.propertyCache ||= createSymbolTable(); + properties.set(name, property); + } + } + } + return property; + } + + function getCommonDeclarationsOfSymbols(symbols: Iterable) { + let commonDeclarations: Set | undefined; + for (const symbol of symbols) { + if (!symbol.declarations) { + return undefined; + } + if (!commonDeclarations) { + commonDeclarations = new Set(symbol.declarations); + continue; + } + commonDeclarations.forEach(declaration => { + if (!contains(symbol.declarations, declaration)) { + commonDeclarations!.delete(declaration); + } + }); + if (commonDeclarations.size === 0) { + return undefined; + } + } + return commonDeclarations; + } + + function getPropertyOfUnionOrIntersectionType(type: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { + const property = getUnionOrIntersectionProperty(type, name, skipObjectFunctionPropertyAugment); + // We need to filter out partial properties in union types + return property && !(getCheckFlags(property) & CheckFlags.ReadPartial) ? property : undefined; + } + + /** + * Return the reduced form of the given type. For a union type, it is a union of the normalized constituent types. + * For an intersection of types containing one or more mututally exclusive discriminant properties, it is 'never'. + * For all other types, it is simply the type itself. Discriminant properties are considered mutually exclusive when + * no constituent property has type 'never', but the intersection of the constituent property types is 'never'. + */ + function getReducedType(type: Type): Type { + if (type.flags & TypeFlags.Union && (type as UnionType).objectFlags & ObjectFlags.ContainsIntersections) { + return (type as UnionType).resolvedReducedType || ((type as UnionType).resolvedReducedType = getReducedUnionType(type as UnionType)); + } + else if (type.flags & TypeFlags.Intersection) { + if (!((type as IntersectionType).objectFlags & ObjectFlags.IsNeverIntersectionComputed)) { + (type as IntersectionType).objectFlags |= ObjectFlags.IsNeverIntersectionComputed | + (some(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isNeverReducedProperty) ? ObjectFlags.IsNeverIntersection : 0); + } + return (type as IntersectionType).objectFlags & ObjectFlags.IsNeverIntersection ? neverType : type; + } + return type; + } + + function getReducedUnionType(unionType: UnionType) { + const reducedTypes = sameMap(unionType.types, getReducedType); + if (reducedTypes === unionType.types) { + return unionType; + } + const reduced = getUnionType(reducedTypes); + if (reduced.flags & TypeFlags.Union) { + (reduced as UnionType).resolvedReducedType = reduced; + } + return reduced; + } + + function isNeverReducedProperty(prop: Symbol) { + return isDiscriminantWithNeverType(prop) || isConflictingPrivateProperty(prop); + } + + function isDiscriminantWithNeverType(prop: Symbol) { + // Return true for a synthetic non-optional property with non-uniform types, where at least one is + // a literal type and none is never, that reduces to never. + return !(prop.flags & SymbolFlags.Optional) && + (getCheckFlags(prop) & (CheckFlags.Discriminant | CheckFlags.HasNeverType)) === CheckFlags.Discriminant && + !!(getTypeOfSymbol(prop).flags & TypeFlags.Never); + } + + function isConflictingPrivateProperty(prop: Symbol) { + // Return true for a synthetic property with multiple declarations, at least one of which is private. + return !prop.valueDeclaration && !!(getCheckFlags(prop) & CheckFlags.ContainsPrivate); + } + + /** + * A union type which is reducible upon instantiation (meaning some members are removed under certain instantiations) + * must be kept generic, as that instantiation information needs to flow through the type system. By replacing all + * type parameters in the union with a special never type that is treated as a literal in `getReducedType`, we can cause + * the `getReducedType` logic to reduce the resulting type if possible (since only intersections with conflicting + * literal-typed properties are reducible). + */ + function isGenericReducibleType(type: Type): boolean { + return !!(type.flags & TypeFlags.Union && (type as UnionType).objectFlags & ObjectFlags.ContainsIntersections && some((type as UnionType).types, isGenericReducibleType) || + type.flags & TypeFlags.Intersection && isReducibleIntersection(type as IntersectionType)); + } + + function isReducibleIntersection(type: IntersectionType) { + const uniqueFilled = type.uniqueLiteralFilledInstantiation || (type.uniqueLiteralFilledInstantiation = instantiateType(type, uniqueLiteralMapper)); + return getReducedType(uniqueFilled) !== uniqueFilled; + } + + function elaborateNeverIntersection(errorInfo: DiagnosticMessageChain | undefined, type: Type) { + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsNeverIntersection) { + const neverProp = find(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isDiscriminantWithNeverType); + if (neverProp) { + return chainDiagnosticMessages(errorInfo, Diagnostics.The_intersection_0_was_reduced_to_never_because_property_1_has_conflicting_types_in_some_constituents, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.NoTypeReduction), symbolToString(neverProp)); + } + const privateProp = find(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isConflictingPrivateProperty); + if (privateProp) { + return chainDiagnosticMessages(errorInfo, Diagnostics.The_intersection_0_was_reduced_to_never_because_property_1_exists_in_multiple_constituents_and_is_private_in_some, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.NoTypeReduction), symbolToString(privateProp)); + } + } + return errorInfo; + } + + /** + * Return the symbol for the property with the given name in the given type. Creates synthetic union properties when + * necessary, maps primitive types and type parameters are to their apparent types, and augments with properties from + * Object and Function as appropriate. + * + * @param type a type to look up property from + * @param name a name of property to look up in a given type + */ + function getPropertyOfType(type: Type, name: __String, skipObjectFunctionPropertyAugment?: boolean, includeTypeOnlyMembers?: boolean): Symbol | undefined { + type = getReducedApparentType(type); + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + const symbol = resolved.members.get(name); + if (symbol && !includeTypeOnlyMembers && type.symbol?.flags & SymbolFlags.ValueModule && getSymbolLinks(type.symbol).typeOnlyExportStarMap?.has(name)) { + // If this is the type of a module, `resolved.members.get(name)` might have effectively skipped over + // an `export type * from './foo'`, leaving `symbolIsValue` unable to see that the symbol is being + // viewed through a type-only export. + return undefined; + } + if (symbol && symbolIsValue(symbol, includeTypeOnlyMembers)) { + return symbol; + } + if (skipObjectFunctionPropertyAugment) return undefined; + const functionType = resolved === anyFunctionType ? globalFunctionType : + resolved.callSignatures.length ? globalCallableFunctionType : + resolved.constructSignatures.length ? globalNewableFunctionType : + undefined; + if (functionType) { + const symbol = getPropertyOfObjectType(functionType, name); + if (symbol) { + return symbol; + } + } + return getPropertyOfObjectType(globalObjectType, name); + } + if (type.flags & TypeFlags.Intersection) { + const prop = getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, /*skipObjectFunctionPropertyAugment*/ true); + if (prop) { + return prop; + } + if (!skipObjectFunctionPropertyAugment) { + return getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, skipObjectFunctionPropertyAugment); + } + return undefined; + } + if (type.flags & TypeFlags.Union) { + return getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, skipObjectFunctionPropertyAugment); + } + return undefined; + } + + function getSignaturesOfStructuredType(type: Type, kind: SignatureKind): readonly Signature[] { + if (type.flags & TypeFlags.StructuredType) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + return kind === SignatureKind.Call ? resolved.callSignatures : resolved.constructSignatures; + } + return emptyArray; + } + + /** + * Return the signatures of the given kind in the given type. Creates synthetic union signatures when necessary and + * maps primitive types and type parameters are to their apparent types. + */ + function getSignaturesOfType(type: Type, kind: SignatureKind): readonly Signature[] { + const result = getSignaturesOfStructuredType(getReducedApparentType(type), kind); + if (kind === SignatureKind.Call && !length(result) && type.flags & TypeFlags.Union) { + if ((type as UnionType).arrayFallbackSignatures) { + return (type as UnionType).arrayFallbackSignatures!; + } + // If the union is all different instantiations of a member of the global array type... + let memberName: __String; + if (everyType(type, t => !!t.symbol?.parent && isArrayOrTupleSymbol(t.symbol.parent) && (!memberName ? (memberName = t.symbol.escapedName, true) : memberName === t.symbol.escapedName))) { + // Transform the type from `(A[] | B[])["member"]` to `(A | B)[]["member"]` (since we pretend array is covariant anyway) + const arrayArg = mapType(type, t => getMappedType((isReadonlyArraySymbol(t.symbol.parent) ? globalReadonlyArrayType : globalArrayType).typeParameters![0], (t as AnonymousType).mapper!)); + const arrayType = createArrayType(arrayArg, someType(type, t => isReadonlyArraySymbol(t.symbol.parent))); + return (type as UnionType).arrayFallbackSignatures = getSignaturesOfType(getTypeOfPropertyOfType(arrayType, memberName!)!, kind); + } + (type as UnionType).arrayFallbackSignatures = result; + } + return result; + } + + function isArrayOrTupleSymbol(symbol: Symbol | undefined) { + if (!symbol || !globalArrayType.symbol || !globalReadonlyArrayType.symbol) { + return false; + } + return !!getSymbolIfSameReference(symbol, globalArrayType.symbol) || !!getSymbolIfSameReference(symbol, globalReadonlyArrayType.symbol); + } + + function isReadonlyArraySymbol(symbol: Symbol | undefined) { + if (!symbol || !globalReadonlyArrayType.symbol) { + return false; + } + return !!getSymbolIfSameReference(symbol, globalReadonlyArrayType.symbol); + } + + function findIndexInfo(indexInfos: readonly IndexInfo[], keyType: Type) { + return find(indexInfos, info => info.keyType === keyType); + } + + function findApplicableIndexInfo(indexInfos: readonly IndexInfo[], keyType: Type) { + // Index signatures for type 'string' are considered only when no other index signatures apply. + let stringIndexInfo: IndexInfo | undefined; + let applicableInfo: IndexInfo | undefined; + let applicableInfos: IndexInfo[] | undefined; + for (const info of indexInfos) { + if (info.keyType === stringType) { + stringIndexInfo = info; + } + else if (isApplicableIndexType(keyType, info.keyType)) { + if (!applicableInfo) { + applicableInfo = info; + } + else { + (applicableInfos || (applicableInfos = [applicableInfo])).push(info); + } + } + } + // When more than one index signature is applicable we create a synthetic IndexInfo. Instead of computing + // the intersected key type, we just use unknownType for the key type as nothing actually depends on the + // keyType property of the returned IndexInfo. + return applicableInfos ? createIndexInfo(unknownType, getIntersectionType(map(applicableInfos, info => info.type)), reduceLeft(applicableInfos, (isReadonly, info) => isReadonly && info.isReadonly, /*initial*/ true)) : + applicableInfo ? applicableInfo : + stringIndexInfo && isApplicableIndexType(keyType, stringType) ? stringIndexInfo : + undefined; + } + + function isApplicableIndexType(source: Type, target: Type): boolean { + // A 'string' index signature applies to types assignable to 'string' or 'number', and a 'number' index + // signature applies to types assignable to 'number', `${number}` and numeric string literal types. + return isTypeAssignableTo(source, target) || + target === stringType && isTypeAssignableTo(source, numberType) || + target === numberType && (source === numericStringType || !!(source.flags & TypeFlags.StringLiteral) && isNumericLiteralName((source as StringLiteralType).value)); + } + + function getIndexInfosOfStructuredType(type: Type): readonly IndexInfo[] { + if (type.flags & TypeFlags.StructuredType) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + return resolved.indexInfos; + } + return emptyArray; + } + + function getIndexInfosOfType(type: Type): readonly IndexInfo[] { + return getIndexInfosOfStructuredType(getReducedApparentType(type)); + } + + // Return the indexing info of the given kind in the given type. Creates synthetic union index types when necessary and + // maps primitive types and type parameters are to their apparent types. + function getIndexInfoOfType(type: Type, keyType: Type): IndexInfo | undefined { + return findIndexInfo(getIndexInfosOfType(type), keyType); + } + + // Return the index type of the given kind in the given type. Creates synthetic union index types when necessary and + // maps primitive types and type parameters are to their apparent types. + function getIndexTypeOfType(type: Type, keyType: Type): Type | undefined { + return getIndexInfoOfType(type, keyType)?.type; + } + + function getApplicableIndexInfos(type: Type, keyType: Type): IndexInfo[] { + return getIndexInfosOfType(type).filter(info => isApplicableIndexType(keyType, info.keyType)); + } + + function getApplicableIndexInfo(type: Type, keyType: Type): IndexInfo | undefined { + return findApplicableIndexInfo(getIndexInfosOfType(type), keyType); + } + + function getApplicableIndexInfoForName(type: Type, name: __String): IndexInfo | undefined { + return getApplicableIndexInfo(type, isLateBoundName(name) ? esSymbolType : getStringLiteralType(unescapeLeadingUnderscores(name))); + } + + // Return list of type parameters with duplicates removed (duplicate identifier errors are generated in the actual + // type checking functions). + function getTypeParametersFromDeclaration(declaration: DeclarationWithTypeParameters): readonly TypeParameter[] | undefined { + let result: TypeParameter[] | undefined; + for (const node of getEffectiveTypeParameterDeclarations(declaration)) { + result = appendIfUnique(result, getDeclaredTypeOfTypeParameter(node.symbol)); + } + return result?.length ? result + : isFunctionDeclaration(declaration) ? getSignatureOfTypeTag(declaration)?.typeParameters + : undefined; + } + + function symbolsToArray(symbols: SymbolTable): Symbol[] { + const result: Symbol[] = []; + symbols.forEach((symbol, id) => { + if (!isReservedMemberName(id)) { + result.push(symbol); + } + }); + return result; + } + + function tryFindAmbientModule(moduleName: string, withAugmentations: boolean) { + if (isExternalModuleNameRelative(moduleName)) { + return undefined; + } + const symbol = getSymbol(globals, '"' + moduleName + '"' as __String, SymbolFlags.ValueModule); + // merged symbol is module declaration symbol combined with all augmentations + return symbol && withAugmentations ? getMergedSymbol(symbol) : symbol; + } + + function hasEffectiveQuestionToken(node: ParameterDeclaration | JSDocParameterTag | JSDocPropertyTag) { + return hasQuestionToken(node) || isOptionalJSDocPropertyLikeTag(node) || isParameter(node) && isJSDocOptionalParameter(node); + } + + function isOptionalParameter(node: ParameterDeclaration | JSDocParameterTag | JSDocPropertyTag) { + if (hasEffectiveQuestionToken(node)) { + return true; + } + if (!isParameter(node)) { + return false; + } + if (node.initializer) { + const signature = getSignatureFromDeclaration(node.parent); + const parameterIndex = node.parent.parameters.indexOf(node); + Debug.assert(parameterIndex >= 0); + // Only consider syntactic or instantiated parameters as optional, not `void` parameters as this function is used + // in grammar checks and checking for `void` too early results in parameter types widening too early + // and causes some noImplicitAny errors to be lost. + return parameterIndex >= getMinArgumentCount(signature, MinArgumentCountFlags.StrongArityForUntypedJS | MinArgumentCountFlags.VoidIsNonOptional); + } + const iife = getImmediatelyInvokedFunctionExpression(node.parent); + if (iife) { + return !node.type && + !node.dotDotDotToken && + node.parent.parameters.indexOf(node) >= getEffectiveCallArguments(iife).length; + } + + return false; + } + + function isOptionalPropertyDeclaration(node: Declaration) { + return isPropertyDeclaration(node) && !hasAccessorModifier(node) && node.questionToken; + } + + function createTypePredicate(kind: TypePredicateKind, parameterName: string | undefined, parameterIndex: number | undefined, type: Type | undefined): TypePredicate { + return { kind, parameterName, parameterIndex, type } as TypePredicate; + } + + /** + * Gets the minimum number of type arguments needed to satisfy all non-optional type + * parameters. + */ + function getMinTypeArgumentCount(typeParameters: readonly TypeParameter[] | undefined): number { + let minTypeArgumentCount = 0; + if (typeParameters) { + for (let i = 0; i < typeParameters.length; i++) { + if (!hasTypeParameterDefault(typeParameters[i])) { + minTypeArgumentCount = i + 1; + } + } + } + return minTypeArgumentCount; + } + + /** + * Fill in default types for unsupplied type arguments. If `typeArguments` is undefined + * when a default type is supplied, a new array will be created and returned. + * + * @param typeArguments The supplied type arguments. + * @param typeParameters The requested type parameters. + * @param minTypeArgumentCount The minimum number of required type arguments. + */ + function fillMissingTypeArguments(typeArguments: readonly Type[], typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean): Type[]; + function fillMissingTypeArguments(typeArguments: readonly Type[] | undefined, typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean): Type[] | undefined; + function fillMissingTypeArguments(typeArguments: readonly Type[] | undefined, typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean) { + const numTypeParameters = length(typeParameters); + if (!numTypeParameters) { + return []; + } + const numTypeArguments = length(typeArguments); + if (isJavaScriptImplicitAny || (numTypeArguments >= minTypeArgumentCount && numTypeArguments <= numTypeParameters)) { + const result = typeArguments ? typeArguments.slice() : []; + // Map invalid forward references in default types to the error type + for (let i = numTypeArguments; i < numTypeParameters; i++) { + result[i] = errorType; + } + const baseDefaultType = getDefaultTypeArgumentType(isJavaScriptImplicitAny); + for (let i = numTypeArguments; i < numTypeParameters; i++) { + let defaultType = getDefaultFromTypeParameter(typeParameters![i]); + if (isJavaScriptImplicitAny && defaultType && (isTypeIdenticalTo(defaultType, unknownType) || isTypeIdenticalTo(defaultType, emptyObjectType))) { + defaultType = anyType; + } + result[i] = defaultType ? instantiateType(defaultType, createTypeMapper(typeParameters!, result)) : baseDefaultType; + } + result.length = typeParameters!.length; + return result; + } + return typeArguments && typeArguments.slice(); + } + + function getSignatureFromDeclaration(declaration: SignatureDeclaration | JSDocSignature): Signature { + const links = getNodeLinks(declaration); + if (!links.resolvedSignature) { + const parameters: Symbol[] = []; + let flags = SignatureFlags.None; + let minArgumentCount = 0; + let thisParameter: Symbol | undefined; + let thisTag: JSDocThisTag | undefined = isInJSFile(declaration) ? getJSDocThisTag(declaration) : undefined; + let hasThisParameter = false; + const iife = getImmediatelyInvokedFunctionExpression(declaration); + const isJSConstructSignature = isJSDocConstructSignature(declaration); + const isUntypedSignatureInJSFile = !iife && + isInJSFile(declaration) && + isValueSignatureDeclaration(declaration) && + !hasJSDocParameterTags(declaration) && + !getJSDocType(declaration); + if (isUntypedSignatureInJSFile) { + flags |= SignatureFlags.IsUntypedSignatureInJSFile; + } + + // If this is a JSDoc construct signature, then skip the first parameter in the + // parameter list. The first parameter represents the return type of the construct + // signature. + for (let i = isJSConstructSignature ? 1 : 0; i < declaration.parameters.length; i++) { + const param = declaration.parameters[i]; + if (isInJSFile(param) && isJSDocThisTag(param)) { + thisTag = param; + continue; + } + + let paramSymbol = param.symbol; + const type = isJSDocParameterTag(param) ? (param.typeExpression && param.typeExpression.type) : param.type; + // Include parameter symbol instead of property symbol in the signature + if (paramSymbol && !!(paramSymbol.flags & SymbolFlags.Property) && !isBindingPattern(param.name)) { + const resolvedSymbol = resolveName(param, paramSymbol.escapedName, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + paramSymbol = resolvedSymbol!; + } + if (i === 0 && paramSymbol.escapedName === InternalSymbolName.This) { + hasThisParameter = true; + thisParameter = param.symbol; + } + else { + parameters.push(paramSymbol); + } + + if (type && type.kind === SyntaxKind.LiteralType) { + flags |= SignatureFlags.HasLiteralTypes; + } + + // Record a new minimum argument count if this is not an optional parameter + const isOptionalParameter = hasEffectiveQuestionToken(param) || + isParameter(param) && param.initializer || isRestParameter(param) || + iife && parameters.length > iife.arguments.length && !type; + if (!isOptionalParameter) { + minArgumentCount = parameters.length; + } + } + + // If only one accessor includes a this-type annotation, the other behaves as if it had the same type annotation + if ( + (declaration.kind === SyntaxKind.GetAccessor || declaration.kind === SyntaxKind.SetAccessor) && + hasBindableName(declaration) && + (!hasThisParameter || !thisParameter) + ) { + const otherKind = declaration.kind === SyntaxKind.GetAccessor ? SyntaxKind.SetAccessor : SyntaxKind.GetAccessor; + const other = getDeclarationOfKind(getSymbolOfDeclaration(declaration), otherKind); + if (other) { + thisParameter = getAnnotatedAccessorThisParameter(other); + } + } + + if (thisTag && thisTag.typeExpression) { + thisParameter = createSymbolWithType(createSymbol(SymbolFlags.FunctionScopedVariable, InternalSymbolName.This), getTypeFromTypeNode(thisTag.typeExpression)); + } + + const hostDeclaration = isJSDocSignature(declaration) ? getEffectiveJSDocHost(declaration) : declaration; + const classType = hostDeclaration && isConstructorDeclaration(hostDeclaration) ? + getDeclaredTypeOfClassOrInterface(getMergedSymbol((hostDeclaration.parent as ClassDeclaration).symbol)) + : undefined; + const typeParameters = classType ? classType.localTypeParameters : getTypeParametersFromDeclaration(declaration); + if (hasRestParameter(declaration) || isInJSFile(declaration) && maybeAddJsSyntheticRestParameter(declaration, parameters)) { + flags |= SignatureFlags.HasRestParameter; + } + if ( + isConstructorTypeNode(declaration) && hasSyntacticModifier(declaration, ModifierFlags.Abstract) || + isConstructorDeclaration(declaration) && hasSyntacticModifier(declaration.parent, ModifierFlags.Abstract) + ) { + flags |= SignatureFlags.Abstract; + } + links.resolvedSignature = createSignature(declaration, typeParameters, thisParameter, parameters, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, minArgumentCount, flags); + } + return links.resolvedSignature; + } + + /** + * A JS function gets a synthetic rest parameter if it references `arguments` AND: + * 1. It has no parameters but at least one `@param` with a type that starts with `...` + * OR + * 2. It has at least one parameter, and the last parameter has a matching `@param` with a type that starts with `...` + */ + function maybeAddJsSyntheticRestParameter(declaration: SignatureDeclaration | JSDocSignature, parameters: Symbol[]): boolean { + if (isJSDocSignature(declaration) || !containsArgumentsReference(declaration)) { + return false; + } + const lastParam = lastOrUndefined(declaration.parameters); + const lastParamTags = lastParam ? getJSDocParameterTags(lastParam) : getJSDocTags(declaration).filter(isJSDocParameterTag); + const lastParamVariadicType = firstDefined(lastParamTags, p => p.typeExpression && isJSDocVariadicType(p.typeExpression.type) ? p.typeExpression.type : undefined); + + const syntheticArgsSymbol = createSymbol(SymbolFlags.Variable, "args" as __String, CheckFlags.RestParameter); + if (lastParamVariadicType) { + // Parameter has effective annotation, lock in type + syntheticArgsSymbol.links.type = createArrayType(getTypeFromTypeNode(lastParamVariadicType.type)); + } + else { + // Parameter has no annotation + // By using a `DeferredType` symbol, we allow the type of this rest arg to be overriden by contextual type assignment so long as its type hasn't been + // cached by `getTypeOfSymbol` yet. + syntheticArgsSymbol.links.checkFlags |= CheckFlags.DeferredType; + syntheticArgsSymbol.links.deferralParent = neverType; + syntheticArgsSymbol.links.deferralConstituents = [anyArrayType]; + syntheticArgsSymbol.links.deferralWriteConstituents = [anyArrayType]; + } + if (lastParamVariadicType) { + // Replace the last parameter with a rest parameter. + parameters.pop(); + } + parameters.push(syntheticArgsSymbol); + return true; + } + + function getSignatureOfTypeTag(node: SignatureDeclaration | JSDocSignature) { + // should be attached to a function declaration or expression + if (!(isInJSFile(node) && isFunctionLikeDeclaration(node))) return undefined; + const typeTag = getJSDocTypeTag(node); + return typeTag?.typeExpression && getSingleCallSignature(getTypeFromTypeNode(typeTag.typeExpression)); + } + + function getParameterTypeOfTypeTag(func: FunctionLikeDeclaration, parameter: ParameterDeclaration) { + const signature = getSignatureOfTypeTag(func); + if (!signature) return undefined; + const pos = func.parameters.indexOf(parameter); + return parameter.dotDotDotToken ? getRestTypeAtPosition(signature, pos) : getTypeAtPosition(signature, pos); + } + + function getReturnTypeOfTypeTag(node: SignatureDeclaration | JSDocSignature) { + const signature = getSignatureOfTypeTag(node); + return signature && getReturnTypeOfSignature(signature); + } + + function containsArgumentsReference(declaration: SignatureDeclaration): boolean { + const links = getNodeLinks(declaration); + if (links.containsArgumentsReference === undefined) { + if (links.flags & NodeCheckFlags.CaptureArguments) { + links.containsArgumentsReference = true; + } + else { + links.containsArgumentsReference = traverse((declaration as FunctionLikeDeclaration).body!); + } + } + return links.containsArgumentsReference; + + function traverse(node: Node): boolean { + if (!node) return false; + switch (node.kind) { + case SyntaxKind.Identifier: + return (node as Identifier).escapedText === argumentsSymbol.escapedName && getReferencedValueSymbol(node as Identifier) === argumentsSymbol; + + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return (node as NamedDeclaration).name!.kind === SyntaxKind.ComputedPropertyName + && traverse((node as NamedDeclaration).name!); + + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + return traverse((node as PropertyAccessExpression | ElementAccessExpression).expression); + + case SyntaxKind.PropertyAssignment: + return traverse((node as PropertyAssignment).initializer); + + default: + return !nodeStartsNewLexicalEnvironment(node) && !isPartOfTypeNode(node) && !!forEachChild(node, traverse); + } + } + } + + function getSignaturesOfSymbol(symbol: Symbol | undefined): Signature[] { + if (!symbol || !symbol.declarations) return emptyArray; + const result: Signature[] = []; + for (let i = 0; i < symbol.declarations.length; i++) { + const decl = symbol.declarations[i]; + if (!isFunctionLike(decl)) continue; + // Don't include signature if node is the implementation of an overloaded function. A node is considered + // an implementation node if it has a body and the previous node is of the same kind and immediately + // precedes the implementation node (i.e. has the same parent and ends where the implementation starts). + if (i > 0 && (decl as FunctionLikeDeclaration).body) { + const previous = symbol.declarations[i - 1]; + if (decl.parent === previous.parent && decl.kind === previous.kind && decl.pos === previous.end) { + continue; + } + } + if (isInJSFile(decl) && decl.jsDoc) { + const tags = getJSDocOverloadTags(decl); + if (length(tags)) { + for (const tag of tags) { + const jsDocSignature = tag.typeExpression; + if (jsDocSignature.type === undefined && !isConstructorDeclaration(decl)) { + reportImplicitAny(jsDocSignature, anyType); + } + result.push(getSignatureFromDeclaration(jsDocSignature)); + } + continue; + } + } + // If this is a function or method declaration, get the signature from the @type tag for the sake of optional parameters. + // Exclude contextually-typed kinds because we already apply the @type tag to the context, plus applying it here to the initializer would supress checks that the two are compatible. + result.push( + (!isFunctionExpressionOrArrowFunction(decl) && + !isObjectLiteralMethod(decl) && + getSignatureOfTypeTag(decl)) || + getSignatureFromDeclaration(decl), + ); + } + return result; + } + + function resolveExternalModuleTypeByLiteral(name: StringLiteral) { + const moduleSym = resolveExternalModuleName(name, name); + if (moduleSym) { + const resolvedModuleSymbol = resolveExternalModuleSymbol(moduleSym); + if (resolvedModuleSymbol) { + return getTypeOfSymbol(resolvedModuleSymbol); + } + } + + return anyType; + } + + function getThisTypeOfSignature(signature: Signature): Type | undefined { + if (signature.thisParameter) { + return getTypeOfSymbol(signature.thisParameter); + } + } + + function getTypePredicateOfSignature(signature: Signature): TypePredicate | undefined { + if (!signature.resolvedTypePredicate) { + if (signature.target) { + const targetTypePredicate = getTypePredicateOfSignature(signature.target); + signature.resolvedTypePredicate = targetTypePredicate ? instantiateTypePredicate(targetTypePredicate, signature.mapper!) : noTypePredicate; + } + else if (signature.compositeSignatures) { + signature.resolvedTypePredicate = getUnionOrIntersectionTypePredicate(signature.compositeSignatures, signature.compositeKind) || noTypePredicate; + } + else { + const type = signature.declaration && getEffectiveReturnTypeNode(signature.declaration); + let jsdocPredicate: TypePredicate | undefined; + if (!type) { + const jsdocSignature = getSignatureOfTypeTag(signature.declaration!); + if (jsdocSignature && signature !== jsdocSignature) { + jsdocPredicate = getTypePredicateOfSignature(jsdocSignature); + } + } + if (type || jsdocPredicate) { + signature.resolvedTypePredicate = type && isTypePredicateNode(type) ? + createTypePredicateFromTypePredicateNode(type, signature) : + jsdocPredicate || noTypePredicate; + } + else if (signature.declaration && isFunctionLikeDeclaration(signature.declaration) && (!signature.resolvedReturnType || signature.resolvedReturnType.flags & TypeFlags.Boolean) && getParameterCount(signature) > 0) { + const { declaration } = signature; + signature.resolvedTypePredicate = noTypePredicate; // avoid infinite loop + signature.resolvedTypePredicate = getTypePredicateFromBody(declaration) || noTypePredicate; + } + else { + signature.resolvedTypePredicate = noTypePredicate; + } + } + Debug.assert(!!signature.resolvedTypePredicate); + } + return signature.resolvedTypePredicate === noTypePredicate ? undefined : signature.resolvedTypePredicate; + } + + function createTypePredicateFromTypePredicateNode(node: TypePredicateNode, signature: Signature): TypePredicate { + const parameterName = node.parameterName; + const type = node.type && getTypeFromTypeNode(node.type); + return parameterName.kind === SyntaxKind.ThisType ? + createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsThis : TypePredicateKind.This, /*parameterName*/ undefined, /*parameterIndex*/ undefined, type) : + createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsIdentifier : TypePredicateKind.Identifier, parameterName.escapedText as string, findIndex(signature.parameters, p => p.escapedName === parameterName.escapedText), type); + } + + function getUnionOrIntersectionType(types: Type[], kind: TypeFlags | undefined, unionReduction?: UnionReduction) { + return kind !== TypeFlags.Intersection ? getUnionType(types, unionReduction) : getIntersectionType(types); + } + + function getReturnTypeOfSignature(signature: Signature): Type { + if (!signature.resolvedReturnType) { + if (!pushTypeResolution(signature, TypeSystemPropertyName.ResolvedReturnType)) { + return errorType; + } + let type = signature.target ? instantiateType(getReturnTypeOfSignature(signature.target), signature.mapper) : + signature.compositeSignatures ? instantiateType(getUnionOrIntersectionType(map(signature.compositeSignatures, getReturnTypeOfSignature), signature.compositeKind, UnionReduction.Subtype), signature.mapper) : + getReturnTypeFromAnnotation(signature.declaration!) || + (nodeIsMissing((signature.declaration as FunctionLikeDeclaration).body) ? anyType : getReturnTypeFromBody(signature.declaration as FunctionLikeDeclaration)); + if (signature.flags & SignatureFlags.IsInnerCallChain) { + type = addOptionalTypeMarker(type); + } + else if (signature.flags & SignatureFlags.IsOuterCallChain) { + type = getOptionalType(type); + } + if (!popTypeResolution()) { + if (signature.declaration) { + const typeNode = getEffectiveReturnTypeNode(signature.declaration); + if (typeNode) { + error(typeNode, Diagnostics.Return_type_annotation_circularly_references_itself); + } + else if (noImplicitAny) { + const declaration = signature.declaration as Declaration; + const name = getNameOfDeclaration(declaration); + if (name) { + error(name, Diagnostics._0_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions, declarationNameToString(name)); + } + else { + error(declaration, Diagnostics.Function_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions); + } + } + } + type = anyType; + } + signature.resolvedReturnType ??= type; + } + return signature.resolvedReturnType; + } + + function getReturnTypeFromAnnotation(declaration: SignatureDeclaration | JSDocSignature) { + if (declaration.kind === SyntaxKind.Constructor) { + return getDeclaredTypeOfClassOrInterface(getMergedSymbol((declaration.parent as ClassDeclaration).symbol)); + } + const typeNode = getEffectiveReturnTypeNode(declaration); + if (isJSDocSignature(declaration)) { + const root = getJSDocRoot(declaration); + if (root && isConstructorDeclaration(root.parent) && !typeNode) { + return getDeclaredTypeOfClassOrInterface(getMergedSymbol((root.parent.parent as ClassDeclaration).symbol)); + } + } + if (isJSDocConstructSignature(declaration)) { + return getTypeFromTypeNode((declaration.parameters[0] as ParameterDeclaration).type!); // TODO: GH#18217 + } + if (typeNode) { + return getTypeFromTypeNode(typeNode); + } + if (declaration.kind === SyntaxKind.GetAccessor && hasBindableName(declaration)) { + const jsDocType = isInJSFile(declaration) && getTypeForDeclarationFromJSDocComment(declaration); + if (jsDocType) { + return jsDocType; + } + const setter = getDeclarationOfKind(getSymbolOfDeclaration(declaration), SyntaxKind.SetAccessor); + const setterType = getAnnotatedAccessorType(setter); + if (setterType) { + return setterType; + } + } + return getReturnTypeOfTypeTag(declaration); + } + + function isResolvingReturnTypeOfSignature(signature: Signature): boolean { + return signature.compositeSignatures && some(signature.compositeSignatures, isResolvingReturnTypeOfSignature) || + !signature.resolvedReturnType && findResolutionCycleStartIndex(signature, TypeSystemPropertyName.ResolvedReturnType) >= 0; + } + + function getRestTypeOfSignature(signature: Signature): Type { + return tryGetRestTypeOfSignature(signature) || anyType; + } + + function tryGetRestTypeOfSignature(signature: Signature): Type | undefined { + if (signatureHasRestParameter(signature)) { + const sigRestType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + const restType = isTupleType(sigRestType) ? getRestTypeOfTupleType(sigRestType) : sigRestType; + return restType && getIndexTypeOfType(restType, numberType); + } + return undefined; + } + + function getSignatureInstantiation(signature: Signature, typeArguments: readonly Type[] | undefined, isJavascript: boolean, inferredTypeParameters?: readonly TypeParameter[]): Signature { + const instantiatedSignature = getSignatureInstantiationWithoutFillingInTypeArguments(signature, fillMissingTypeArguments(typeArguments, signature.typeParameters, getMinTypeArgumentCount(signature.typeParameters), isJavascript)); + if (inferredTypeParameters) { + const returnSignature = getSingleCallOrConstructSignature(getReturnTypeOfSignature(instantiatedSignature)); + if (returnSignature) { + const newReturnSignature = cloneSignature(returnSignature); + newReturnSignature.typeParameters = inferredTypeParameters; + const newInstantiatedSignature = cloneSignature(instantiatedSignature); + newInstantiatedSignature.resolvedReturnType = getOrCreateTypeFromSignature(newReturnSignature); + return newInstantiatedSignature; + } + } + return instantiatedSignature; + } + + function getSignatureInstantiationWithoutFillingInTypeArguments(signature: Signature, typeArguments: readonly Type[] | undefined): Signature { + const instantiations = signature.instantiations || (signature.instantiations = new Map()); + const id = getTypeListId(typeArguments); + let instantiation = instantiations.get(id); + if (!instantiation) { + instantiations.set(id, instantiation = createSignatureInstantiation(signature, typeArguments)); + } + return instantiation; + } + + function createSignatureInstantiation(signature: Signature, typeArguments: readonly Type[] | undefined): Signature { + return instantiateSignature(signature, createSignatureTypeMapper(signature, typeArguments), /*eraseTypeParameters*/ true); + } + + function createSignatureTypeMapper(signature: Signature, typeArguments: readonly Type[] | undefined): TypeMapper { + return createTypeMapper(signature.typeParameters!, typeArguments); + } + + function getErasedSignature(signature: Signature): Signature { + return signature.typeParameters ? + signature.erasedSignatureCache || (signature.erasedSignatureCache = createErasedSignature(signature)) : + signature; + } + + function createErasedSignature(signature: Signature) { + // Create an instantiation of the signature where all type arguments are the any type. + return instantiateSignature(signature, createTypeEraser(signature.typeParameters!), /*eraseTypeParameters*/ true); + } + + function getCanonicalSignature(signature: Signature): Signature { + return signature.typeParameters ? + signature.canonicalSignatureCache || (signature.canonicalSignatureCache = createCanonicalSignature(signature)) : + signature; + } + + function createCanonicalSignature(signature: Signature) { + // Create an instantiation of the signature where each unconstrained type parameter is replaced with + // its original. When a generic class or interface is instantiated, each generic method in the class or + // interface is instantiated with a fresh set of cloned type parameters (which we need to handle scenarios + // where different generations of the same type parameter are in scope). This leads to a lot of new type + // identities, and potentially a lot of work comparing those identities, so here we create an instantiation + // that uses the original type identities for all unconstrained type parameters. + return getSignatureInstantiation( + signature, + map(signature.typeParameters, tp => tp.target && !getConstraintOfTypeParameter(tp.target) ? tp.target : tp), + isInJSFile(signature.declaration), + ); + } + + function getImplementationSignature(signature: Signature) { + return signature.typeParameters ? + signature.implementationSignatureCache ||= createImplementationSignature(signature) : + signature; + } + + function createImplementationSignature(signature: Signature) { + return signature.typeParameters ? instantiateSignature(signature, createTypeMapper([], [])) : signature; + } + + function getBaseSignature(signature: Signature) { + const typeParameters = signature.typeParameters; + if (typeParameters) { + if (signature.baseSignatureCache) { + return signature.baseSignatureCache; + } + const typeEraser = createTypeEraser(typeParameters); + const baseConstraintMapper = createTypeMapper(typeParameters, map(typeParameters, tp => getConstraintOfTypeParameter(tp) || unknownType)); + let baseConstraints: readonly Type[] = map(typeParameters, tp => instantiateType(tp, baseConstraintMapper) || unknownType); + // Run N type params thru the immediate constraint mapper up to N times + // This way any noncircular interdependent type parameters are definitely resolved to their external dependencies + for (let i = 0; i < typeParameters.length - 1; i++) { + baseConstraints = instantiateTypes(baseConstraints, baseConstraintMapper); + } + // and then apply a type eraser to remove any remaining circularly dependent type parameters + baseConstraints = instantiateTypes(baseConstraints, typeEraser); + return signature.baseSignatureCache = instantiateSignature(signature, createTypeMapper(typeParameters, baseConstraints), /*eraseTypeParameters*/ true); + } + return signature; + } + + function getOrCreateTypeFromSignature(signature: Signature, outerTypeParameters?: TypeParameter[]): ObjectType { + // There are two ways to declare a construct signature, one is by declaring a class constructor + // using the constructor keyword, and the other is declaring a bare construct signature in an + // object type literal or interface (using the new keyword). Each way of declaring a constructor + // will result in a different declaration kind. + if (!signature.isolatedSignatureType) { + const kind = signature.declaration?.kind; + + // If declaration is undefined, it is likely to be the signature of the default constructor. + const isConstructor = kind === undefined || kind === SyntaxKind.Constructor || kind === SyntaxKind.ConstructSignature || kind === SyntaxKind.ConstructorType; + + // The type must have a symbol with a `Function` flag and a declaration in order to be correctly flagged as possibly containing + // type variables by `couldContainTypeVariables` + const type = createObjectType(ObjectFlags.Anonymous | ObjectFlags.SingleSignatureType, createSymbol(SymbolFlags.Function, InternalSymbolName.Function)) as SingleSignatureType; + if (signature.declaration && !nodeIsSynthesized(signature.declaration)) { // skip synthetic declarations - keeping those around could be bad, since they lack a parent pointer + type.symbol.declarations = [signature.declaration]; + type.symbol.valueDeclaration = signature.declaration; + } + outerTypeParameters ||= signature.declaration && getOuterTypeParameters(signature.declaration, /*includeThisTypes*/ true); + type.outerTypeParameters = outerTypeParameters; + + type.members = emptySymbols; + type.properties = emptyArray; + type.callSignatures = !isConstructor ? [signature] : emptyArray; + type.constructSignatures = isConstructor ? [signature] : emptyArray; + type.indexInfos = emptyArray; + signature.isolatedSignatureType = type; + } + + return signature.isolatedSignatureType; + } + + function getIndexSymbol(symbol: Symbol): Symbol | undefined { + return symbol.members ? getIndexSymbolFromSymbolTable(symbol.members) : undefined; + } + + function getIndexSymbolFromSymbolTable(symbolTable: SymbolTable): Symbol | undefined { + return symbolTable.get(InternalSymbolName.Index); + } + + function createIndexInfo(keyType: Type, type: Type, isReadonly: boolean, declaration?: IndexSignatureDeclaration): IndexInfo { + return { keyType, type, isReadonly, declaration }; + } + + function getIndexInfosOfSymbol(symbol: Symbol): IndexInfo[] { + const indexSymbol = getIndexSymbol(symbol); + return indexSymbol ? getIndexInfosOfIndexSymbol(indexSymbol) : emptyArray; + } + + function getIndexInfosOfIndexSymbol(indexSymbol: Symbol): IndexInfo[] { + if (indexSymbol.declarations) { + const indexInfos: IndexInfo[] = []; + for (const declaration of (indexSymbol.declarations as IndexSignatureDeclaration[])) { + if (declaration.parameters.length === 1) { + const parameter = declaration.parameters[0]; + if (parameter.type) { + forEachType(getTypeFromTypeNode(parameter.type), keyType => { + if (isValidIndexKeyType(keyType) && !findIndexInfo(indexInfos, keyType)) { + indexInfos.push(createIndexInfo(keyType, declaration.type ? getTypeFromTypeNode(declaration.type) : anyType, hasEffectiveModifier(declaration, ModifierFlags.Readonly), declaration)); + } + }); + } + } + } + return indexInfos; + } + return emptyArray; + } + + function isValidIndexKeyType(type: Type): boolean { + return !!(type.flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.ESSymbol)) || isPatternLiteralType(type) || + !!(type.flags & TypeFlags.Intersection) && !isGenericType(type) && some((type as IntersectionType).types, isValidIndexKeyType); + } + + function getConstraintDeclaration(type: TypeParameter): TypeNode | undefined { + return mapDefined(filter(type.symbol && type.symbol.declarations, isTypeParameterDeclaration), getEffectiveConstraintOfTypeParameter)[0]; + } + + function getInferredTypeParameterConstraint(typeParameter: TypeParameter, omitTypeReferences?: boolean) { + let inferences: Type[] | undefined; + if (typeParameter.symbol?.declarations) { + for (const declaration of typeParameter.symbol.declarations) { + if (declaration.parent.kind === SyntaxKind.InferType) { + // When an 'infer T' declaration is immediately contained in a type reference node + // (such as 'Foo'), T's constraint is inferred from the constraint of the + // corresponding type parameter in 'Foo'. When multiple 'infer T' declarations are + // present, we form an intersection of the inferred constraint types. + const [childTypeParameter = declaration.parent, grandParent] = walkUpParenthesizedTypesAndGetParentAndChild(declaration.parent.parent); + if (grandParent.kind === SyntaxKind.TypeReference && !omitTypeReferences) { + const typeReference = grandParent as TypeReferenceNode; + const typeParameters = getTypeParametersForTypeReferenceOrImport(typeReference); + if (typeParameters) { + const index = typeReference.typeArguments!.indexOf(childTypeParameter as TypeNode); + if (index < typeParameters.length) { + const declaredConstraint = getConstraintOfTypeParameter(typeParameters[index]); + if (declaredConstraint) { + // Type parameter constraints can reference other type parameters so + // constraints need to be instantiated. If instantiation produces the + // type parameter itself, we discard that inference. For example, in + // type Foo = [T, U]; + // type Bar = T extends Foo ? Foo : T; + // the instantiated constraint for U is X, so we discard that inference. + const mapper = makeDeferredTypeMapper( + typeParameters, + typeParameters.map((_, index) => () => { + return getEffectiveTypeArgumentAtIndex(typeReference, typeParameters, index); + }), + ); + const constraint = instantiateType(declaredConstraint, mapper); + if (constraint !== typeParameter) { + inferences = append(inferences, constraint); + } + } + } + } + } + // When an 'infer T' declaration is immediately contained in a rest parameter declaration, a rest type + // or a named rest tuple element, we infer an 'unknown[]' constraint. + else if ( + grandParent.kind === SyntaxKind.Parameter && (grandParent as ParameterDeclaration).dotDotDotToken || + grandParent.kind === SyntaxKind.RestType || + grandParent.kind === SyntaxKind.NamedTupleMember && (grandParent as NamedTupleMember).dotDotDotToken + ) { + inferences = append(inferences, createArrayType(unknownType)); + } + // When an 'infer T' declaration is immediately contained in a string template type, we infer a 'string' + // constraint. + else if (grandParent.kind === SyntaxKind.TemplateLiteralTypeSpan) { + inferences = append(inferences, stringType); + } + // When an 'infer T' declaration is in the constraint position of a mapped type, we infer a 'keyof any' + // constraint. + else if (grandParent.kind === SyntaxKind.TypeParameter && grandParent.parent.kind === SyntaxKind.MappedType) { + inferences = append(inferences, stringNumberSymbolType); + } + // When an 'infer T' declaration is the template of a mapped type, and that mapped type is the extends + // clause of a conditional whose check type is also a mapped type, give it a constraint equal to the template + // of the check type's mapped type + else if ( + grandParent.kind === SyntaxKind.MappedType && (grandParent as MappedTypeNode).type && + skipParentheses((grandParent as MappedTypeNode).type!) === declaration.parent && grandParent.parent.kind === SyntaxKind.ConditionalType && + (grandParent.parent as ConditionalTypeNode).extendsType === grandParent && (grandParent.parent as ConditionalTypeNode).checkType.kind === SyntaxKind.MappedType && + ((grandParent.parent as ConditionalTypeNode).checkType as MappedTypeNode).type + ) { + const checkMappedType = (grandParent.parent as ConditionalTypeNode).checkType as MappedTypeNode; + const nodeType = getTypeFromTypeNode(checkMappedType.type!); + inferences = append(inferences, instantiateType(nodeType, makeUnaryTypeMapper(getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(checkMappedType.typeParameter)), checkMappedType.typeParameter.constraint ? getTypeFromTypeNode(checkMappedType.typeParameter.constraint) : stringNumberSymbolType))); + } + } + } + } + return inferences && getIntersectionType(inferences); + } + + /** This is a worker function. Use getConstraintOfTypeParameter which guards against circular constraints. */ + function getConstraintFromTypeParameter(typeParameter: TypeParameter): Type | undefined { + if (!typeParameter.constraint) { + if (typeParameter.target) { + const targetConstraint = getConstraintOfTypeParameter(typeParameter.target); + typeParameter.constraint = targetConstraint ? instantiateType(targetConstraint, typeParameter.mapper) : noConstraintType; + } + else { + const constraintDeclaration = getConstraintDeclaration(typeParameter); + if (!constraintDeclaration) { + typeParameter.constraint = getInferredTypeParameterConstraint(typeParameter) || noConstraintType; + } + else { + let type = getTypeFromTypeNode(constraintDeclaration); + if (type.flags & TypeFlags.Any && !isErrorType(type)) { // Allow errorType to propegate to keep downstream errors suppressed + // use stringNumberSymbolType as the base constraint for mapped type key constraints (unknown isn;t assignable to that, but `any` was), + // use unknown otherwise + type = constraintDeclaration.parent.parent.kind === SyntaxKind.MappedType ? stringNumberSymbolType : unknownType; + } + typeParameter.constraint = type; + } + } + } + return typeParameter.constraint === noConstraintType ? undefined : typeParameter.constraint; + } + + function getParentSymbolOfTypeParameter(typeParameter: TypeParameter): Symbol | undefined { + const tp = getDeclarationOfKind(typeParameter.symbol, SyntaxKind.TypeParameter)!; + const host = isJSDocTemplateTag(tp.parent) ? getEffectiveContainerForJSDocTemplateTag(tp.parent) : tp.parent; + return host && getSymbolOfNode(host); + } + + function getTypeListId(types: readonly Type[] | undefined) { + let result = ""; + if (types) { + const length = types.length; + let i = 0; + while (i < length) { + const startId = types[i].id; + let count = 1; + while (i + count < length && types[i + count].id === startId + count) { + count++; + } + if (result.length) { + result += ","; + } + result += startId; + if (count > 1) { + result += ":" + count; + } + i += count; + } + } + return result; + } + + function getAliasId(aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { + return aliasSymbol ? `@${getSymbolId(aliasSymbol)}` + (aliasTypeArguments ? `:${getTypeListId(aliasTypeArguments)}` : "") : ""; + } + + // This function is used to propagate certain flags when creating new object type references and union types. + // It is only necessary to do so if a constituent type might be the undefined type, the null type, the type + // of an object literal or a non-inferrable type. This is because there are operations in the type checker + // that care about the presence of such types at arbitrary depth in a containing type. + function getPropagatingFlagsOfTypes(types: readonly Type[], excludeKinds?: TypeFlags): ObjectFlags { + let result: ObjectFlags = 0; + for (const type of types) { + if (excludeKinds === undefined || !(type.flags & excludeKinds)) { + result |= getObjectFlags(type); + } + } + return result & ObjectFlags.PropagatingFlags; + } + + function tryCreateTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined): Type { + if (some(typeArguments) && target === emptyGenericType) { + return unknownType; + } + + return createTypeReference(target, typeArguments); + } + + function createTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined): TypeReference { + const id = getTypeListId(typeArguments); + let type = target.instantiations.get(id); + if (!type) { + type = createObjectType(ObjectFlags.Reference, target.symbol) as TypeReference; + target.instantiations.set(id, type); + type.objectFlags |= typeArguments ? getPropagatingFlagsOfTypes(typeArguments) : 0; + type.target = target; + type.resolvedTypeArguments = typeArguments; + } + return type; + } + + function cloneTypeReference(source: TypeReference): TypeReference { + const type = createTypeWithSymbol(source.flags, source.symbol) as TypeReference; + type.objectFlags = source.objectFlags; + type.target = source.target; + type.resolvedTypeArguments = source.resolvedTypeArguments; + return type; + } + + function createDeferredTypeReference(target: GenericType, node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, mapper?: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): DeferredTypeReference { + if (!aliasSymbol) { + aliasSymbol = getAliasSymbolForTypeNode(node); + const localAliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); + aliasTypeArguments = mapper ? instantiateTypes(localAliasTypeArguments, mapper) : localAliasTypeArguments; + } + const type = createObjectType(ObjectFlags.Reference, target.symbol) as DeferredTypeReference; + type.target = target; + type.node = node; + type.mapper = mapper; + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = aliasTypeArguments; + return type; + } + + function getTypeArguments(type: TypeReference): readonly Type[] { + if (!type.resolvedTypeArguments) { + if (!pushTypeResolution(type, TypeSystemPropertyName.ResolvedTypeArguments)) { + return type.target.localTypeParameters?.map(() => errorType) || emptyArray; + } + const node = type.node; + const typeArguments = !node ? emptyArray : + node.kind === SyntaxKind.TypeReference ? concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters!)) : + node.kind === SyntaxKind.ArrayType ? [getTypeFromTypeNode(node.elementType)] : + map(node.elements, getTypeFromTypeNode); + if (popTypeResolution()) { + type.resolvedTypeArguments ??= type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments; + } + else { + type.resolvedTypeArguments ??= type.target.localTypeParameters?.map(() => errorType) || emptyArray; + error( + type.node || currentNode, + type.target.symbol ? Diagnostics.Type_arguments_for_0_circularly_reference_themselves : Diagnostics.Tuple_type_arguments_circularly_reference_themselves, + type.target.symbol && symbolToString(type.target.symbol), + ); + } + } + return type.resolvedTypeArguments; + } + + function getTypeReferenceArity(type: TypeReference): number { + return length(type.target.typeParameters); + } + + /** + * Get type from type-reference that reference to class or interface + */ + function getTypeFromClassOrInterfaceReference(node: NodeWithTypeArguments, symbol: Symbol): Type { + const type = getDeclaredTypeOfSymbol(getMergedSymbol(symbol)) as InterfaceType; + const typeParameters = type.localTypeParameters; + if (typeParameters) { + const numTypeArguments = length(node.typeArguments); + const minTypeArgumentCount = getMinTypeArgumentCount(typeParameters); + const isJs = isInJSFile(node); + const isJsImplicitAny = !noImplicitAny && isJs; + if (!isJsImplicitAny && (numTypeArguments < minTypeArgumentCount || numTypeArguments > typeParameters.length)) { + const missingAugmentsTag = isJs && isExpressionWithTypeArguments(node) && !isJSDocAugmentsTag(node.parent); + const diag = minTypeArgumentCount === typeParameters.length ? + missingAugmentsTag ? + Diagnostics.Expected_0_type_arguments_provide_these_with_an_extends_tag : + Diagnostics.Generic_type_0_requires_1_type_argument_s : + missingAugmentsTag ? + Diagnostics.Expected_0_1_type_arguments_provide_these_with_an_extends_tag : + Diagnostics.Generic_type_0_requires_between_1_and_2_type_arguments; + + const typeStr = typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType); + error(node, diag, typeStr, minTypeArgumentCount, typeParameters.length); + if (!isJs) { + // TODO: Adopt same permissive behavior in TS as in JS to reduce follow-on editing experience failures (requires editing fillMissingTypeArguments) + return errorType; + } + } + if (node.kind === SyntaxKind.TypeReference && isDeferredTypeReferenceNode(node as TypeReferenceNode, length(node.typeArguments) !== typeParameters.length)) { + return createDeferredTypeReference(type as GenericType, node as TypeReferenceNode, /*mapper*/ undefined); + } + // In a type reference, the outer type parameters of the referenced class or interface are automatically + // supplied as type arguments and the type reference only specifies arguments for the local type parameters + // of the class or interface. + const typeArguments = concatenate(type.outerTypeParameters, fillMissingTypeArguments(typeArgumentsFromTypeReferenceNode(node), typeParameters, minTypeArgumentCount, isJs)); + return createTypeReference(type as GenericType, typeArguments); + } + return checkNoTypeArguments(node, symbol) ? type : errorType; + } + + function getTypeAliasInstantiation(symbol: Symbol, typeArguments: readonly Type[] | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + const type = getDeclaredTypeOfSymbol(symbol); + if (type === intrinsicMarkerType) { + const typeKind = intrinsicTypeKinds.get(symbol.escapedName as string); + if (typeKind !== undefined && typeArguments && typeArguments.length === 1) { + return typeKind === IntrinsicTypeKind.NoInfer ? getNoInferType(typeArguments[0]) : getStringMappingType(symbol, typeArguments[0]); + } + } + const links = getSymbolLinks(symbol); + const typeParameters = links.typeParameters!; + const id = getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments); + let instantiation = links.instantiations!.get(id); + if (!instantiation) { + links.instantiations!.set(id, instantiation = instantiateTypeWithAlias(type, createTypeMapper(typeParameters, fillMissingTypeArguments(typeArguments, typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(symbol.valueDeclaration))), aliasSymbol, aliasTypeArguments)); + } + return instantiation; + } + + /** + * Get type from reference to type alias. When a type alias is generic, the declared type of the type alias may include + * references to the type parameters of the alias. We replace those with the actual type arguments by instantiating the + * declared type. Instantiations are cached using the type identities of the type arguments as the key. + */ + function getTypeFromTypeAliasReference(node: NodeWithTypeArguments, symbol: Symbol): Type { + if (getCheckFlags(symbol) & CheckFlags.Unresolved) { + const typeArguments = typeArgumentsFromTypeReferenceNode(node); + const id = getAliasId(symbol, typeArguments); + let errorType = errorTypes.get(id); + if (!errorType) { + errorType = createIntrinsicType(TypeFlags.Any, "error", /*objectFlags*/ undefined, `alias ${id}`); + errorType.aliasSymbol = symbol; + errorType.aliasTypeArguments = typeArguments; + errorTypes.set(id, errorType); + } + return errorType; + } + const type = getDeclaredTypeOfSymbol(symbol); + const typeParameters = getSymbolLinks(symbol).typeParameters; + if (typeParameters) { + const numTypeArguments = length(node.typeArguments); + const minTypeArgumentCount = getMinTypeArgumentCount(typeParameters); + if (numTypeArguments < minTypeArgumentCount || numTypeArguments > typeParameters.length) { + error( + node, + minTypeArgumentCount === typeParameters.length ? + Diagnostics.Generic_type_0_requires_1_type_argument_s : + Diagnostics.Generic_type_0_requires_between_1_and_2_type_arguments, + symbolToString(symbol), + minTypeArgumentCount, + typeParameters.length, + ); + return errorType; + } + // We refrain from associating a local type alias with an instantiation of a top-level type alias + // because the local alias may end up being referenced in an inferred return type where it is not + // accessible--which in turn may lead to a large structural expansion of the type when generating + // a .d.ts file. See #43622 for an example. + const aliasSymbol = getAliasSymbolForTypeNode(node); + let newAliasSymbol = aliasSymbol && (isLocalTypeAlias(symbol) || !isLocalTypeAlias(aliasSymbol)) ? aliasSymbol : undefined; + let aliasTypeArguments: Type[] | undefined; + if (newAliasSymbol) { + aliasTypeArguments = getTypeArgumentsForAliasSymbol(newAliasSymbol); + } + else if (isTypeReferenceType(node)) { + const aliasSymbol = resolveTypeReferenceName(node, SymbolFlags.Alias, /*ignoreErrors*/ true); + // refers to an alias import/export/reexport - by making sure we use the target as an aliasSymbol, + // we ensure the exported symbol is used to refer to the type when it's reserialized later + if (aliasSymbol && aliasSymbol !== unknownSymbol) { + const resolved = resolveAlias(aliasSymbol); + if (resolved && resolved.flags & SymbolFlags.TypeAlias) { + newAliasSymbol = resolved; + aliasTypeArguments = typeArgumentsFromTypeReferenceNode(node) || (typeParameters ? [] : undefined); + } + } + } + return getTypeAliasInstantiation(symbol, typeArgumentsFromTypeReferenceNode(node), newAliasSymbol, aliasTypeArguments); + } + return checkNoTypeArguments(node, symbol) ? type : errorType; + } + + function isLocalTypeAlias(symbol: Symbol) { + const declaration = symbol.declarations?.find(isTypeAlias); + return !!(declaration && getContainingFunction(declaration)); + } + + function getTypeReferenceName(node: TypeReferenceType): EntityNameOrEntityNameExpression | undefined { + switch (node.kind) { + case SyntaxKind.TypeReference: + return node.typeName; + case SyntaxKind.ExpressionWithTypeArguments: + // We only support expressions that are simple qualified names. For other + // expressions this produces undefined. + const expr = node.expression; + if (isEntityNameExpression(expr)) { + return expr; + } + // fall through; + } + + return undefined; + } + + function getSymbolPath(symbol: Symbol): string { + return symbol.parent ? `${getSymbolPath(symbol.parent)}.${symbol.escapedName}` : symbol.escapedName as string; + } + + function getUnresolvedSymbolForEntityName(name: EntityNameOrEntityNameExpression) { + const identifier = name.kind === SyntaxKind.QualifiedName ? name.right : + name.kind === SyntaxKind.PropertyAccessExpression ? name.name : + name; + const text = identifier.escapedText; + if (text) { + const parentSymbol = name.kind === SyntaxKind.QualifiedName ? getUnresolvedSymbolForEntityName(name.left) : + name.kind === SyntaxKind.PropertyAccessExpression ? getUnresolvedSymbolForEntityName(name.expression) : + undefined; + const path = parentSymbol ? `${getSymbolPath(parentSymbol)}.${text}` : text as string; + let result = unresolvedSymbols.get(path); + if (!result) { + unresolvedSymbols.set(path, result = createSymbol(SymbolFlags.TypeAlias, text, CheckFlags.Unresolved)); + result.parent = parentSymbol; + result.links.declaredType = unresolvedType; + } + return result; + } + return unknownSymbol; + } + + function resolveTypeReferenceName(typeReference: TypeReferenceType, meaning: SymbolFlags, ignoreErrors?: boolean) { + const name = getTypeReferenceName(typeReference); + if (!name) { + return unknownSymbol; + } + const symbol = resolveEntityName(name, meaning, ignoreErrors); + return symbol && symbol !== unknownSymbol ? symbol : + ignoreErrors ? unknownSymbol : getUnresolvedSymbolForEntityName(name); + } + + function getTypeReferenceType(node: NodeWithTypeArguments, symbol: Symbol): Type { + if (symbol === unknownSymbol) { + return errorType; + } + symbol = getExpandoSymbol(symbol) || symbol; + if (symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { + return getTypeFromClassOrInterfaceReference(node, symbol); + } + if (symbol.flags & SymbolFlags.TypeAlias) { + return getTypeFromTypeAliasReference(node, symbol); + } + // Get type from reference to named type that cannot be generic (enum or type parameter) + const res = tryGetDeclaredTypeOfSymbol(symbol); + if (res) { + return checkNoTypeArguments(node, symbol) ? getRegularTypeOfLiteralType(res) : errorType; + } + if (symbol.flags & SymbolFlags.Value && isJSDocTypeReference(node)) { + const jsdocType = getTypeFromJSDocValueReference(node, symbol); + if (jsdocType) { + return jsdocType; + } + else { + // Resolve the type reference as a Type for the purpose of reporting errors. + resolveTypeReferenceName(node, SymbolFlags.Type); + return getTypeOfSymbol(symbol); + } + } + return errorType; + } + + /** + * A JSdoc TypeReference may be to a value, but resolve it as a type anyway. + * Example: import('./b').ConstructorFunction + */ + function getTypeFromJSDocValueReference(node: NodeWithTypeArguments, symbol: Symbol): Type | undefined { + const links = getNodeLinks(node); + if (!links.resolvedJSDocType) { + const valueType = getTypeOfSymbol(symbol); + let typeType = valueType; + if (symbol.valueDeclaration) { + const isImportTypeWithQualifier = node.kind === SyntaxKind.ImportType && (node as ImportTypeNode).qualifier; + // valueType might not have a symbol, eg, {import('./b').STRING_LITERAL} + if (valueType.symbol && valueType.symbol !== symbol && isImportTypeWithQualifier) { + typeType = getTypeReferenceType(node, valueType.symbol); + } + } + links.resolvedJSDocType = typeType; + } + return links.resolvedJSDocType; + } + + function getNoInferType(type: Type) { + return isNoInferTargetType(type) ? getOrCreateSubstitutionType(type, unknownType) : type; + } + + function isNoInferTargetType(type: Type): boolean { + // This is effectively a more conservative and predictable form of couldContainTypeVariables. We want to + // preserve NoInfer only for types that could contain type variables, but we don't want to exhaustively + // examine all object type members. + return !!(type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, isNoInferTargetType) || + type.flags & TypeFlags.Substitution && !isNoInferType(type) && isNoInferTargetType((type as SubstitutionType).baseType) || + type.flags & TypeFlags.Object && !isEmptyAnonymousObjectType(type) || + type.flags & (TypeFlags.Instantiable & ~TypeFlags.Substitution) && !isPatternLiteralType(type)); + } + + function isNoInferType(type: Type) { + // A NoInfer type is represented as a substitution type with a TypeFlags.Unknown constraint. + return !!(type.flags & TypeFlags.Substitution && (type as SubstitutionType).constraint.flags & TypeFlags.Unknown); + } + + function getSubstitutionType(baseType: Type, constraint: Type) { + return constraint.flags & TypeFlags.AnyOrUnknown || constraint === baseType || baseType.flags & TypeFlags.Any ? + baseType : + getOrCreateSubstitutionType(baseType, constraint); + } + + function getOrCreateSubstitutionType(baseType: Type, constraint: Type) { + const id = `${getTypeId(baseType)}>${getTypeId(constraint)}`; + const cached = substitutionTypes.get(id); + if (cached) { + return cached; + } + const result = createType(TypeFlags.Substitution) as SubstitutionType; + result.baseType = baseType; + result.constraint = constraint; + substitutionTypes.set(id, result); + return result; + } + + function getSubstitutionIntersection(substitutionType: SubstitutionType) { + return isNoInferType(substitutionType) ? substitutionType.baseType : getIntersectionType([substitutionType.constraint, substitutionType.baseType]); + } + + function isUnaryTupleTypeNode(node: TypeNode) { + return node.kind === SyntaxKind.TupleType && (node as TupleTypeNode).elements.length === 1; + } + + function getImpliedConstraint(type: Type, checkNode: TypeNode, extendsNode: TypeNode): Type | undefined { + return isUnaryTupleTypeNode(checkNode) && isUnaryTupleTypeNode(extendsNode) ? getImpliedConstraint(type, (checkNode as TupleTypeNode).elements[0], (extendsNode as TupleTypeNode).elements[0]) : + getActualTypeVariable(getTypeFromTypeNode(checkNode)) === getActualTypeVariable(type) ? getTypeFromTypeNode(extendsNode) : + undefined; + } + + function getConditionalFlowTypeOfType(type: Type, node: Node) { + let constraints: Type[] | undefined; + let covariant = true; + while (node && !isStatement(node) && node.kind !== SyntaxKind.JSDoc) { + const parent = node.parent; + // only consider variance flipped by parameter locations - `keyof` types would usually be considered variance inverting, but + // often get used in indexed accesses where they behave sortof invariantly, but our checking is lax + if (parent.kind === SyntaxKind.Parameter) { + covariant = !covariant; + } + // Always substitute on type parameters, regardless of variance, since even + // in contravariant positions, they may rely on substituted constraints to be valid + if ((covariant || type.flags & TypeFlags.TypeVariable) && parent.kind === SyntaxKind.ConditionalType && node === (parent as ConditionalTypeNode).trueType) { + const constraint = getImpliedConstraint(type, (parent as ConditionalTypeNode).checkType, (parent as ConditionalTypeNode).extendsType); + if (constraint) { + constraints = append(constraints, constraint); + } + } + // Given a homomorphic mapped type { [K in keyof T]: XXX }, where T is constrained to an array or tuple type, in the + // template type XXX, K has an added constraint of number | `${number}`. + else if (type.flags & TypeFlags.TypeParameter && parent.kind === SyntaxKind.MappedType && !(parent as MappedTypeNode).nameType && node === (parent as MappedTypeNode).type) { + const mappedType = getTypeFromTypeNode(parent as TypeNode) as MappedType; + if (getTypeParameterFromMappedType(mappedType) === getActualTypeVariable(type)) { + const typeParameter = getHomomorphicTypeVariable(mappedType); + if (typeParameter) { + const constraint = getConstraintOfTypeParameter(typeParameter); + if (constraint && everyType(constraint, isArrayOrTupleType)) { + constraints = append(constraints, getUnionType([numberType, numericStringType])); + } + } + } + } + node = parent; + } + return constraints ? getSubstitutionType(type, getIntersectionType(constraints)) : type; + } + + function isJSDocTypeReference(node: Node): node is TypeReferenceNode { + return !!(node.flags & NodeFlags.JSDoc) && (node.kind === SyntaxKind.TypeReference || node.kind === SyntaxKind.ImportType); + } + + function checkNoTypeArguments(node: NodeWithTypeArguments, symbol?: Symbol) { + if (node.typeArguments) { + error(node, Diagnostics.Type_0_is_not_generic, symbol ? symbolToString(symbol) : (node as TypeReferenceNode).typeName ? declarationNameToString((node as TypeReferenceNode).typeName) : anon); + return false; + } + return true; + } + + function getIntendedTypeFromJSDocTypeReference(node: TypeReferenceNode): Type | undefined { + if (isIdentifier(node.typeName)) { + const typeArgs = node.typeArguments; + switch (node.typeName.escapedText) { + case "String": + checkNoTypeArguments(node); + return stringType; + case "Number": + checkNoTypeArguments(node); + return numberType; + case "Boolean": + checkNoTypeArguments(node); + return booleanType; + case "Void": + checkNoTypeArguments(node); + return voidType; + case "Undefined": + checkNoTypeArguments(node); + return undefinedType; + case "Null": + checkNoTypeArguments(node); + return nullType; + case "Function": + case "function": + checkNoTypeArguments(node); + return globalFunctionType; + case "array": + return (!typeArgs || !typeArgs.length) && !noImplicitAny ? anyArrayType : undefined; + case "promise": + return (!typeArgs || !typeArgs.length) && !noImplicitAny ? createPromiseType(anyType) : undefined; + case "Object": + if (typeArgs && typeArgs.length === 2) { + if (isJSDocIndexSignature(node)) { + const indexed = getTypeFromTypeNode(typeArgs[0]); + const target = getTypeFromTypeNode(typeArgs[1]); + const indexInfo = indexed === stringType || indexed === numberType ? [createIndexInfo(indexed, target, /*isReadonly*/ false)] : emptyArray; + return createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, indexInfo); + } + return anyType; + } + checkNoTypeArguments(node); + return !noImplicitAny ? anyType : undefined; + } + } + } + + function getTypeFromJSDocNullableTypeNode(node: JSDocNullableType) { + const type = getTypeFromTypeNode(node.type); + return strictNullChecks ? getNullableType(type, TypeFlags.Null) : type; + } + + function getTypeFromTypeReference(node: TypeReferenceType): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + // handle LS queries on the `const` in `x as const` by resolving to the type of `x` + if (isConstTypeReference(node) && isAssertionExpression(node.parent)) { + links.resolvedSymbol = unknownSymbol; + return links.resolvedType = checkExpressionCached(node.parent.expression); + } + let symbol: Symbol | undefined; + let type: Type | undefined; + const meaning = SymbolFlags.Type; + if (isJSDocTypeReference(node)) { + type = getIntendedTypeFromJSDocTypeReference(node); + if (!type) { + symbol = resolveTypeReferenceName(node, meaning, /*ignoreErrors*/ true); + if (symbol === unknownSymbol) { + symbol = resolveTypeReferenceName(node, meaning | SymbolFlags.Value); + } + else { + resolveTypeReferenceName(node, meaning); // Resolve again to mark errors, if any + } + type = getTypeReferenceType(node, symbol); + } + } + if (!type) { + symbol = resolveTypeReferenceName(node, meaning); + type = getTypeReferenceType(node, symbol); + } + // Cache both the resolved symbol and the resolved type. The resolved symbol is needed when we check the + // type reference in checkTypeReferenceNode. + links.resolvedSymbol = symbol; + links.resolvedType = type; + } + return links.resolvedType; + } + + function typeArgumentsFromTypeReferenceNode(node: NodeWithTypeArguments): Type[] | undefined { + return map(node.typeArguments, getTypeFromTypeNode); + } + + function getTypeFromTypeQueryNode(node: TypeQueryNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + // TypeScript 1.0 spec (April 2014): 3.6.3 + // The expression is processed as an identifier expression (section 4.3) + // or property access expression(section 4.10), + // the widened type(section 3.9) of which becomes the result. + const type = checkExpressionWithTypeArguments(node); + links.resolvedType = getRegularTypeOfLiteralType(getWidenedType(type)); + } + return links.resolvedType; + } + + function getTypeOfGlobalSymbol(symbol: Symbol | undefined, arity: number): ObjectType { + function getTypeDeclaration(symbol: Symbol): Declaration | undefined { + const declarations = symbol.declarations; + if (declarations) { + for (const declaration of declarations) { + switch (declaration.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.EnumDeclaration: + return declaration; + } + } + } + } + + if (!symbol) { + return arity ? emptyGenericType : emptyObjectType; + } + const type = getDeclaredTypeOfSymbol(symbol); + if (!(type.flags & TypeFlags.Object)) { + error(getTypeDeclaration(symbol), Diagnostics.Global_type_0_must_be_a_class_or_interface_type, symbolName(symbol)); + return arity ? emptyGenericType : emptyObjectType; + } + if (length((type as InterfaceType).typeParameters) !== arity) { + error(getTypeDeclaration(symbol), Diagnostics.Global_type_0_must_have_1_type_parameter_s, symbolName(symbol), arity); + return arity ? emptyGenericType : emptyObjectType; + } + return type as ObjectType; + } + + function getGlobalValueSymbol(name: __String, reportErrors: boolean): Symbol | undefined { + return getGlobalSymbol(name, SymbolFlags.Value, reportErrors ? Diagnostics.Cannot_find_global_value_0 : undefined); + } + + function getGlobalTypeSymbol(name: __String, reportErrors: boolean): Symbol | undefined { + return getGlobalSymbol(name, SymbolFlags.Type, reportErrors ? Diagnostics.Cannot_find_global_type_0 : undefined); + } + + function getGlobalTypeAliasSymbol(name: __String, arity: number, reportErrors: boolean): Symbol | undefined { + const symbol = getGlobalSymbol(name, SymbolFlags.Type, reportErrors ? Diagnostics.Cannot_find_global_type_0 : undefined); + if (symbol) { + // Resolve the declared type of the symbol. This resolves type parameters for the type + // alias so that we can check arity. + getDeclaredTypeOfSymbol(symbol); + if (length(getSymbolLinks(symbol).typeParameters) !== arity) { + const decl = symbol.declarations && find(symbol.declarations, isTypeAliasDeclaration); + error(decl, Diagnostics.Global_type_0_must_have_1_type_parameter_s, symbolName(symbol), arity); + return undefined; + } + } + return symbol; + } + + function getGlobalSymbol(name: __String, meaning: SymbolFlags, diagnostic: DiagnosticMessage | undefined): Symbol | undefined { + // Don't track references for global symbols anyway, so value if `isReference` is arbitrary + return resolveName(/*location*/ undefined, name, meaning, diagnostic, /*isUse*/ false, /*excludeGlobals*/ false); + } + + function getGlobalType(name: __String, arity: 0, reportErrors: true): ObjectType; + function getGlobalType(name: __String, arity: 0, reportErrors: boolean): ObjectType | undefined; + function getGlobalType(name: __String, arity: number, reportErrors: true): GenericType; + function getGlobalType(name: __String, arity: number, reportErrors: boolean): GenericType | undefined; + function getGlobalType(name: __String, arity: number, reportErrors: boolean): ObjectType | undefined { + const symbol = getGlobalTypeSymbol(name, reportErrors); + return symbol || reportErrors ? getTypeOfGlobalSymbol(symbol, arity) : undefined; + } + + function getGlobalTypedPropertyDescriptorType() { + // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times + return deferredGlobalTypedPropertyDescriptorType ||= getGlobalType("TypedPropertyDescriptor" as __String, /*arity*/ 1, /*reportErrors*/ true) || emptyGenericType; + } + + function getGlobalTemplateStringsArrayType() { + // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times + return deferredGlobalTemplateStringsArrayType ||= getGlobalType("TemplateStringsArray" as __String, /*arity*/ 0, /*reportErrors*/ true) || emptyObjectType; + } + + function getGlobalImportMetaType() { + // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times + return deferredGlobalImportMetaType ||= getGlobalType("ImportMeta" as __String, /*arity*/ 0, /*reportErrors*/ true) || emptyObjectType; + } + + function getGlobalImportMetaExpressionType() { + if (!deferredGlobalImportMetaExpressionType) { + // Create a synthetic type `ImportMetaExpression { meta: MetaProperty }` + const symbol = createSymbol(SymbolFlags.None, "ImportMetaExpression" as __String); + const importMetaType = getGlobalImportMetaType(); + + const metaPropertySymbol = createSymbol(SymbolFlags.Property, "meta" as __String, CheckFlags.Readonly); + metaPropertySymbol.parent = symbol; + metaPropertySymbol.links.type = importMetaType; + + const members = createSymbolTable([metaPropertySymbol]); + symbol.members = members; + + deferredGlobalImportMetaExpressionType = createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + } + return deferredGlobalImportMetaExpressionType; + } + + function getGlobalImportCallOptionsType(reportErrors: boolean) { + return (deferredGlobalImportCallOptionsType ||= getGlobalType("ImportCallOptions" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalImportAttributesType(reportErrors: boolean) { + return (deferredGlobalImportAttributesType ||= getGlobalType("ImportAttributes" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalESSymbolConstructorSymbol(reportErrors: boolean): Symbol | undefined { + return deferredGlobalESSymbolConstructorSymbol ||= getGlobalValueSymbol("Symbol" as __String, reportErrors); + } + + function getGlobalESSymbolConstructorTypeSymbol(reportErrors: boolean): Symbol | undefined { + return deferredGlobalESSymbolConstructorTypeSymbol ||= getGlobalTypeSymbol("SymbolConstructor" as __String, reportErrors); + } + + function getGlobalESSymbolType() { + return (deferredGlobalESSymbolType ||= getGlobalType("Symbol" as __String, /*arity*/ 0, /*reportErrors*/ false)) || emptyObjectType; + } + + function getGlobalPromiseType(reportErrors: boolean) { + return (deferredGlobalPromiseType ||= getGlobalType("Promise" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalPromiseLikeType(reportErrors: boolean) { + return (deferredGlobalPromiseLikeType ||= getGlobalType("PromiseLike" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalPromiseConstructorSymbol(reportErrors: boolean): Symbol | undefined { + return deferredGlobalPromiseConstructorSymbol ||= getGlobalValueSymbol("Promise" as __String, reportErrors); + } + + function getGlobalPromiseConstructorLikeType(reportErrors: boolean) { + return (deferredGlobalPromiseConstructorLikeType ||= getGlobalType("PromiseConstructorLike" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalAsyncIterableType(reportErrors: boolean) { + return (deferredGlobalAsyncIterableType ||= getGlobalType("AsyncIterable" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalAsyncIteratorType(reportErrors: boolean) { + return (deferredGlobalAsyncIteratorType ||= getGlobalType("AsyncIterator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalAsyncIterableIteratorType(reportErrors: boolean) { + return (deferredGlobalAsyncIterableIteratorType ||= getGlobalType("AsyncIterableIterator" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalAsyncGeneratorType(reportErrors: boolean) { + return (deferredGlobalAsyncGeneratorType ||= getGlobalType("AsyncGenerator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalIterableType(reportErrors: boolean) { + return (deferredGlobalIterableType ||= getGlobalType("Iterable" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalIteratorType(reportErrors: boolean) { + return (deferredGlobalIteratorType ||= getGlobalType("Iterator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalIterableIteratorType(reportErrors: boolean) { + return (deferredGlobalIterableIteratorType ||= getGlobalType("IterableIterator" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalGeneratorType(reportErrors: boolean) { + return (deferredGlobalGeneratorType ||= getGlobalType("Generator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalIteratorYieldResultType(reportErrors: boolean) { + return (deferredGlobalIteratorYieldResultType ||= getGlobalType("IteratorYieldResult" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalIteratorReturnResultType(reportErrors: boolean) { + return (deferredGlobalIteratorReturnResultType ||= getGlobalType("IteratorReturnResult" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalDisposableType(reportErrors: boolean) { + return (deferredGlobalDisposableType ||= getGlobalType("Disposable" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalAsyncDisposableType(reportErrors: boolean) { + return (deferredGlobalAsyncDisposableType ||= getGlobalType("AsyncDisposable" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalTypeOrUndefined(name: __String, arity = 0): ObjectType | undefined { + const symbol = getGlobalSymbol(name, SymbolFlags.Type, /*diagnostic*/ undefined); + return symbol && getTypeOfGlobalSymbol(symbol, arity) as GenericType; + } + + function getGlobalExtractSymbol(): Symbol | undefined { + // We always report an error, so cache a result in the event we could not resolve the symbol to prevent reporting it multiple times + deferredGlobalExtractSymbol ||= getGlobalTypeAliasSymbol("Extract" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; + return deferredGlobalExtractSymbol === unknownSymbol ? undefined : deferredGlobalExtractSymbol; + } + + function getGlobalOmitSymbol(): Symbol | undefined { + // We always report an error, so cache a result in the event we could not resolve the symbol to prevent reporting it multiple times + deferredGlobalOmitSymbol ||= getGlobalTypeAliasSymbol("Omit" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; + return deferredGlobalOmitSymbol === unknownSymbol ? undefined : deferredGlobalOmitSymbol; + } + + function getGlobalAwaitedSymbol(reportErrors: boolean): Symbol | undefined { + // Only cache `unknownSymbol` if we are reporting errors so that we don't report the error more than once. + deferredGlobalAwaitedSymbol ||= getGlobalTypeAliasSymbol("Awaited" as __String, /*arity*/ 1, reportErrors) || (reportErrors ? unknownSymbol : undefined); + return deferredGlobalAwaitedSymbol === unknownSymbol ? undefined : deferredGlobalAwaitedSymbol; + } + + function getGlobalBigIntType() { + return (deferredGlobalBigIntType ||= getGlobalType("BigInt" as __String, /*arity*/ 0, /*reportErrors*/ false)) || emptyObjectType; + } + + function getGlobalClassDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassDecoratorContextType ??= getGlobalType("ClassDecoratorContext" as __String, /*arity*/ 1, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassMethodDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassMethodDecoratorContextType ??= getGlobalType("ClassMethodDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassGetterDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassGetterDecoratorContextType ??= getGlobalType("ClassGetterDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassSetterDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassSetterDecoratorContextType ??= getGlobalType("ClassSetterDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassAccessorDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassAccessorDecoratorContextType ??= getGlobalType("ClassAccessorDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassAccessorDecoratorTargetType(reportErrors: boolean) { + return (deferredGlobalClassAccessorDecoratorTargetType ??= getGlobalType("ClassAccessorDecoratorTarget" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassAccessorDecoratorResultType(reportErrors: boolean) { + return (deferredGlobalClassAccessorDecoratorResultType ??= getGlobalType("ClassAccessorDecoratorResult" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassFieldDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassFieldDecoratorContextType ??= getGlobalType("ClassFieldDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalNaNSymbol(): Symbol | undefined { + return (deferredGlobalNaNSymbol ||= getGlobalValueSymbol("NaN" as __String, /*reportErrors*/ false)); + } + + function getGlobalRecordSymbol(): Symbol | undefined { + deferredGlobalRecordSymbol ||= getGlobalTypeAliasSymbol("Record" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; + return deferredGlobalRecordSymbol === unknownSymbol ? undefined : deferredGlobalRecordSymbol; + } + + /** + * Instantiates a global type that is generic with some element type, and returns that instantiation. + */ + function createTypeFromGenericGlobalType(genericGlobalType: GenericType, typeArguments: readonly Type[]): ObjectType { + return genericGlobalType !== emptyGenericType ? createTypeReference(genericGlobalType, typeArguments) : emptyObjectType; + } + + function createTypedPropertyDescriptorType(propertyType: Type): Type { + return createTypeFromGenericGlobalType(getGlobalTypedPropertyDescriptorType(), [propertyType]); + } + + function createIterableType(iteratedType: Type): Type { + return createTypeFromGenericGlobalType(getGlobalIterableType(/*reportErrors*/ true), [iteratedType]); + } + + function createArrayType(elementType: Type, readonly?: boolean): ObjectType { + return createTypeFromGenericGlobalType(readonly ? globalReadonlyArrayType : globalArrayType, [elementType]); + } + + function getTupleElementFlags(node: TypeNode) { + switch (node.kind) { + case SyntaxKind.OptionalType: + return ElementFlags.Optional; + case SyntaxKind.RestType: + return getRestTypeElementFlags(node as RestTypeNode); + case SyntaxKind.NamedTupleMember: + return (node as NamedTupleMember).questionToken ? ElementFlags.Optional : + (node as NamedTupleMember).dotDotDotToken ? getRestTypeElementFlags(node as NamedTupleMember) : + ElementFlags.Required; + default: + return ElementFlags.Required; + } + } + + function getRestTypeElementFlags(node: RestTypeNode | NamedTupleMember) { + return getArrayElementTypeNode(node.type) ? ElementFlags.Rest : ElementFlags.Variadic; + } + + function getArrayOrTupleTargetType(node: ArrayTypeNode | TupleTypeNode): GenericType { + const readonly = isReadonlyTypeOperator(node.parent); + const elementType = getArrayElementTypeNode(node); + if (elementType) { + return readonly ? globalReadonlyArrayType : globalArrayType; + } + const elementFlags = map((node as TupleTypeNode).elements, getTupleElementFlags); + return getTupleTargetType(elementFlags, readonly, map((node as TupleTypeNode).elements, memberIfLabeledElementDeclaration)); + } + + function memberIfLabeledElementDeclaration(member: Node): NamedTupleMember | ParameterDeclaration | undefined { + return isNamedTupleMember(member) || isParameter(member) ? member : undefined; + } + + // Return true if the given type reference node is directly aliased or if it needs to be deferred + // because it is possibly contained in a circular chain of eagerly resolved types. + function isDeferredTypeReferenceNode(node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, hasDefaultTypeArguments?: boolean) { + return !!getAliasSymbolForTypeNode(node) || isResolvedByTypeAlias(node) && ( + node.kind === SyntaxKind.ArrayType ? mayResolveTypeAlias(node.elementType) : + node.kind === SyntaxKind.TupleType ? some(node.elements, mayResolveTypeAlias) : + hasDefaultTypeArguments || some(node.typeArguments, mayResolveTypeAlias) + ); + } + + // Return true when the given node is transitively contained in type constructs that eagerly + // resolve their constituent types. We include SyntaxKind.TypeReference because type arguments + // of type aliases are eagerly resolved. + function isResolvedByTypeAlias(node: Node): boolean { + const parent = node.parent; + switch (parent.kind) { + case SyntaxKind.ParenthesizedType: + case SyntaxKind.NamedTupleMember: + case SyntaxKind.TypeReference: + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + case SyntaxKind.IndexedAccessType: + case SyntaxKind.ConditionalType: + case SyntaxKind.TypeOperator: + case SyntaxKind.ArrayType: + case SyntaxKind.TupleType: + return isResolvedByTypeAlias(parent); + case SyntaxKind.TypeAliasDeclaration: + return true; + } + return false; + } + + // Return true if resolving the given node (i.e. getTypeFromTypeNode) possibly causes resolution + // of a type alias. + function mayResolveTypeAlias(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.TypeReference: + return isJSDocTypeReference(node) || !!(resolveTypeReferenceName(node as TypeReferenceNode, SymbolFlags.Type).flags & SymbolFlags.TypeAlias); + case SyntaxKind.TypeQuery: + return true; + case SyntaxKind.TypeOperator: + return (node as TypeOperatorNode).operator !== SyntaxKind.UniqueKeyword && mayResolveTypeAlias((node as TypeOperatorNode).type); + case SyntaxKind.ParenthesizedType: + case SyntaxKind.OptionalType: + case SyntaxKind.NamedTupleMember: + case SyntaxKind.JSDocOptionalType: + case SyntaxKind.JSDocNullableType: + case SyntaxKind.JSDocNonNullableType: + case SyntaxKind.JSDocTypeExpression: + return mayResolveTypeAlias((node as ParenthesizedTypeNode | OptionalTypeNode | JSDocTypeReferencingNode | NamedTupleMember).type); + case SyntaxKind.RestType: + return (node as RestTypeNode).type.kind !== SyntaxKind.ArrayType || mayResolveTypeAlias(((node as RestTypeNode).type as ArrayTypeNode).elementType); + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + return some((node as UnionOrIntersectionTypeNode).types, mayResolveTypeAlias); + case SyntaxKind.IndexedAccessType: + return mayResolveTypeAlias((node as IndexedAccessTypeNode).objectType) || mayResolveTypeAlias((node as IndexedAccessTypeNode).indexType); + case SyntaxKind.ConditionalType: + return mayResolveTypeAlias((node as ConditionalTypeNode).checkType) || mayResolveTypeAlias((node as ConditionalTypeNode).extendsType) || + mayResolveTypeAlias((node as ConditionalTypeNode).trueType) || mayResolveTypeAlias((node as ConditionalTypeNode).falseType); + } + return false; + } + + function getTypeFromArrayOrTupleTypeNode(node: ArrayTypeNode | TupleTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const target = getArrayOrTupleTargetType(node); + if (target === emptyGenericType) { + links.resolvedType = emptyObjectType; + } + else if (!(node.kind === SyntaxKind.TupleType && some(node.elements, e => !!(getTupleElementFlags(e) & ElementFlags.Variadic))) && isDeferredTypeReferenceNode(node)) { + links.resolvedType = node.kind === SyntaxKind.TupleType && node.elements.length === 0 ? target : + createDeferredTypeReference(target, node, /*mapper*/ undefined); + } + else { + const elementTypes = node.kind === SyntaxKind.ArrayType ? [getTypeFromTypeNode(node.elementType)] : map(node.elements, getTypeFromTypeNode); + links.resolvedType = createNormalizedTypeReference(target, elementTypes); + } + } + return links.resolvedType; + } + + function isReadonlyTypeOperator(node: Node) { + return isTypeOperatorNode(node) && node.operator === SyntaxKind.ReadonlyKeyword; + } + + function createTupleType(elementTypes: readonly Type[], elementFlags?: readonly ElementFlags[], readonly = false, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration | undefined)[] = []) { + const tupleTarget = getTupleTargetType(elementFlags || map(elementTypes, _ => ElementFlags.Required), readonly, namedMemberDeclarations); + return tupleTarget === emptyGenericType ? emptyObjectType : + elementTypes.length ? createNormalizedTypeReference(tupleTarget, elementTypes) : + tupleTarget; + } + + function getTupleTargetType(elementFlags: readonly ElementFlags[], readonly: boolean, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration | undefined)[]): GenericType { + if (elementFlags.length === 1 && elementFlags[0] & ElementFlags.Rest) { + // [...X[]] is equivalent to just X[] + return readonly ? globalReadonlyArrayType : globalArrayType; + } + const key = map(elementFlags, f => f & ElementFlags.Required ? "#" : f & ElementFlags.Optional ? "?" : f & ElementFlags.Rest ? "." : "*").join() + + (readonly ? "R" : "") + + (some(namedMemberDeclarations, node => !!node) ? "," + map(namedMemberDeclarations, node => node ? getNodeId(node) : "_").join(",") : ""); + let type = tupleTypes.get(key); + if (!type) { + tupleTypes.set(key, type = createTupleTargetType(elementFlags, readonly, namedMemberDeclarations)); + } + return type; + } + + // We represent tuple types as type references to synthesized generic interface types created by + // this function. The types are of the form: + // + // interface Tuple extends Array { 0: T0, 1: T1, 2: T2, ... } + // + // Note that the generic type created by this function has no symbol associated with it. The same + // is true for each of the synthesized type parameters. + function createTupleTargetType(elementFlags: readonly ElementFlags[], readonly: boolean, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration | undefined)[]): TupleType { + const arity = elementFlags.length; + const minLength = countWhere(elementFlags, f => !!(f & (ElementFlags.Required | ElementFlags.Variadic))); + let typeParameters: TypeParameter[] | undefined; + const properties: Symbol[] = []; + let combinedFlags = 0 as ElementFlags; + if (arity) { + typeParameters = new Array(arity); + for (let i = 0; i < arity; i++) { + const typeParameter = typeParameters[i] = createTypeParameter(); + const flags = elementFlags[i]; + combinedFlags |= flags; + if (!(combinedFlags & ElementFlags.Variable)) { + const property = createSymbol(SymbolFlags.Property | (flags & ElementFlags.Optional ? SymbolFlags.Optional : 0), "" + i as __String, readonly ? CheckFlags.Readonly : 0); + property.links.tupleLabelDeclaration = namedMemberDeclarations?.[i]; + property.links.type = typeParameter; + properties.push(property); + } + } + } + const fixedLength = properties.length; + const lengthSymbol = createSymbol(SymbolFlags.Property, "length" as __String, readonly ? CheckFlags.Readonly : 0); + if (combinedFlags & ElementFlags.Variable) { + lengthSymbol.links.type = numberType; + } + else { + const literalTypes = []; + for (let i = minLength; i <= arity; i++) literalTypes.push(getNumberLiteralType(i)); + lengthSymbol.links.type = getUnionType(literalTypes); + } + properties.push(lengthSymbol); + const type = createObjectType(ObjectFlags.Tuple | ObjectFlags.Reference) as TupleType & InterfaceTypeWithDeclaredMembers; + type.typeParameters = typeParameters; + type.outerTypeParameters = undefined; + type.localTypeParameters = typeParameters; + type.instantiations = new Map(); + type.instantiations.set(getTypeListId(type.typeParameters), type as GenericType); + type.target = type as GenericType; + type.resolvedTypeArguments = type.typeParameters; + type.thisType = createTypeParameter(); + type.thisType.isThisType = true; + type.thisType.constraint = type; + type.declaredProperties = properties; + type.declaredCallSignatures = emptyArray; + type.declaredConstructSignatures = emptyArray; + type.declaredIndexInfos = emptyArray; + type.elementFlags = elementFlags; + type.minLength = minLength; + type.fixedLength = fixedLength; + type.hasRestElement = !!(combinedFlags & ElementFlags.Variable); + type.combinedFlags = combinedFlags; + type.readonly = readonly; + type.labeledElementDeclarations = namedMemberDeclarations; + return type; + } + + function createNormalizedTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined) { + return target.objectFlags & ObjectFlags.Tuple ? createNormalizedTupleType(target as TupleType, typeArguments!) : createTypeReference(target, typeArguments); + } + + function createNormalizedTupleType(target: TupleType, elementTypes: readonly Type[]): Type { + if (!(target.combinedFlags & ElementFlags.NonRequired)) { + // No need to normalize when we only have regular required elements + return createTypeReference(target, elementTypes); + } + if (target.combinedFlags & ElementFlags.Variadic) { + // Transform [A, ...(X | Y | Z)] into [A, ...X] | [A, ...Y] | [A, ...Z] + const unionIndex = findIndex(elementTypes, (t, i) => !!(target.elementFlags[i] & ElementFlags.Variadic && t.flags & (TypeFlags.Never | TypeFlags.Union))); + if (unionIndex >= 0) { + return checkCrossProductUnion(map(elementTypes, (t, i) => target.elementFlags[i] & ElementFlags.Variadic ? t : unknownType)) ? + mapType(elementTypes[unionIndex], t => createNormalizedTupleType(target, replaceElement(elementTypes, unionIndex, t))) : + errorType; + } + } + // We have optional, rest, or variadic elements that may need normalizing. Normalization ensures that all variadic + // elements are generic and that the tuple type has one of the following layouts, disregarding variadic elements: + // (1) Zero or more required elements, followed by zero or more optional elements, followed by zero or one rest element. + // (2) Zero or more required elements, followed by a rest element, followed by zero or more required elements. + // In either layout, zero or more generic variadic elements may be present at any location. + const expandedTypes: Type[] = []; + const expandedFlags: ElementFlags[] = []; + const expandedDeclarations: (NamedTupleMember | ParameterDeclaration | undefined)[] = []; + let lastRequiredIndex = -1; + let firstRestIndex = -1; + let lastOptionalOrRestIndex = -1; + for (let i = 0; i < elementTypes.length; i++) { + const type = elementTypes[i]; + const flags = target.elementFlags[i]; + if (flags & ElementFlags.Variadic) { + if (type.flags & TypeFlags.Any) { + addElement(type, ElementFlags.Rest, target.labeledElementDeclarations?.[i]); + } + else if (type.flags & TypeFlags.InstantiableNonPrimitive || isGenericMappedType(type)) { + // Generic variadic elements stay as they are. + addElement(type, ElementFlags.Variadic, target.labeledElementDeclarations?.[i]); + } + else if (isTupleType(type)) { + const elements = getElementTypes(type); + if (elements.length + expandedTypes.length >= 10_000) { + error( + currentNode, + isPartOfTypeNode(currentNode!) + ? Diagnostics.Type_produces_a_tuple_type_that_is_too_large_to_represent + : Diagnostics.Expression_produces_a_tuple_type_that_is_too_large_to_represent, + ); + return errorType; + } + // Spread variadic elements with tuple types into the resulting tuple. + forEach(elements, (t, n) => addElement(t, type.target.elementFlags[n], type.target.labeledElementDeclarations?.[n])); + } + else { + // Treat everything else as an array type and create a rest element. + addElement(isArrayLikeType(type) && getIndexTypeOfType(type, numberType) || errorType, ElementFlags.Rest, target.labeledElementDeclarations?.[i]); + } + } + else { + // Copy other element kinds with no change. + addElement(type, flags, target.labeledElementDeclarations?.[i]); + } + } + // Turn optional elements preceding the last required element into required elements + for (let i = 0; i < lastRequiredIndex; i++) { + if (expandedFlags[i] & ElementFlags.Optional) expandedFlags[i] = ElementFlags.Required; + } + if (firstRestIndex >= 0 && firstRestIndex < lastOptionalOrRestIndex) { + // Turn elements between first rest and last optional/rest into a single rest element + expandedTypes[firstRestIndex] = getUnionType(sameMap(expandedTypes.slice(firstRestIndex, lastOptionalOrRestIndex + 1), (t, i) => expandedFlags[firstRestIndex + i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t)); + expandedTypes.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); + expandedFlags.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); + expandedDeclarations.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); + } + const tupleTarget = getTupleTargetType(expandedFlags, target.readonly, expandedDeclarations); + return tupleTarget === emptyGenericType ? emptyObjectType : + expandedFlags.length ? createTypeReference(tupleTarget, expandedTypes) : + tupleTarget; + + function addElement(type: Type, flags: ElementFlags, declaration: NamedTupleMember | ParameterDeclaration | undefined) { + if (flags & ElementFlags.Required) { + lastRequiredIndex = expandedFlags.length; + } + if (flags & ElementFlags.Rest && firstRestIndex < 0) { + firstRestIndex = expandedFlags.length; + } + if (flags & (ElementFlags.Optional | ElementFlags.Rest)) { + lastOptionalOrRestIndex = expandedFlags.length; + } + expandedTypes.push(flags & ElementFlags.Optional ? addOptionality(type, /*isProperty*/ true) : type); + expandedFlags.push(flags); + expandedDeclarations.push(declaration); + } + } + + function sliceTupleType(type: TupleTypeReference, index: number, endSkipCount = 0) { + const target = type.target; + const endIndex = getTypeReferenceArity(type) - endSkipCount; + return index > target.fixedLength ? getRestArrayTypeOfTupleType(type) || createTupleType(emptyArray) : + createTupleType(getTypeArguments(type).slice(index, endIndex), target.elementFlags.slice(index, endIndex), /*readonly*/ false, target.labeledElementDeclarations && target.labeledElementDeclarations.slice(index, endIndex)); + } + + function getKnownKeysOfTupleType(type: TupleTypeReference) { + return getUnionType(append(arrayOf(type.target.fixedLength, i => getStringLiteralType("" + i)), getIndexType(type.target.readonly ? globalReadonlyArrayType : globalArrayType))); + } + + // Return count of starting consecutive tuple elements of the given kind(s) + function getStartElementCount(type: TupleType, flags: ElementFlags) { + const index = findIndex(type.elementFlags, f => !(f & flags)); + return index >= 0 ? index : type.elementFlags.length; + } + + // Return count of ending consecutive tuple elements of the given kind(s) + function getEndElementCount(type: TupleType, flags: ElementFlags) { + return type.elementFlags.length - findLastIndex(type.elementFlags, f => !(f & flags)) - 1; + } + + function getTotalFixedElementCount(type: TupleType) { + return type.fixedLength + getEndElementCount(type, ElementFlags.Fixed); + } + + function getElementTypes(type: TupleTypeReference): readonly Type[] { + const typeArguments = getTypeArguments(type); + const arity = getTypeReferenceArity(type); + return typeArguments.length === arity ? typeArguments : typeArguments.slice(0, arity); + } + + function getTypeFromOptionalTypeNode(node: OptionalTypeNode): Type { + return addOptionality(getTypeFromTypeNode(node.type), /*isProperty*/ true); + } + + function getTypeId(type: Type): TypeId { + return type.id; + } + + function containsType(types: readonly Type[], type: Type): boolean { + return binarySearch(types, type, getTypeId, compareValues) >= 0; + } + + function insertType(types: Type[], type: Type): boolean { + const index = binarySearch(types, type, getTypeId, compareValues); + if (index < 0) { + types.splice(~index, 0, type); + return true; + } + return false; + } + + function addTypeToUnion(typeSet: Type[], includes: TypeFlags, type: Type) { + const flags = type.flags; + // We ignore 'never' types in unions + if (!(flags & TypeFlags.Never)) { + includes |= flags & TypeFlags.IncludesMask; + if (flags & TypeFlags.Instantiable) includes |= TypeFlags.IncludesInstantiable; + if (flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) includes |= TypeFlags.IncludesConstrainedTypeVariable; + if (type === wildcardType) includes |= TypeFlags.IncludesWildcard; + if (isErrorType(type)) includes |= TypeFlags.IncludesError; + if (!strictNullChecks && flags & TypeFlags.Nullable) { + if (!(getObjectFlags(type) & ObjectFlags.ContainsWideningType)) includes |= TypeFlags.IncludesNonWideningType; + } + else { + const len = typeSet.length; + const index = len && type.id > typeSet[len - 1].id ? ~len : binarySearch(typeSet, type, getTypeId, compareValues); + if (index < 0) { + typeSet.splice(~index, 0, type); + } + } + } + return includes; + } + + // Add the given types to the given type set. Order is preserved, duplicates are removed, + // and nested types of the given kind are flattened into the set. + function addTypesToUnion(typeSet: Type[], includes: TypeFlags, types: readonly Type[]): TypeFlags { + let lastType: Type | undefined; + for (const type of types) { + // We skip the type if it is the same as the last type we processed. This simple test particularly + // saves a lot of work for large lists of the same union type, such as when resolving `Record[A]`, + // where A and B are large union types. + if (type !== lastType) { + includes = type.flags & TypeFlags.Union ? + addTypesToUnion(typeSet, includes | (isNamedUnionType(type) ? TypeFlags.Union : 0), (type as UnionType).types) : + addTypeToUnion(typeSet, includes, type); + lastType = type; + } + } + return includes; + } + + function removeSubtypes(types: Type[], hasObjectTypes: boolean): Type[] | undefined { + // [] and [T] immediately reduce to [] and [T] respectively + if (types.length < 2) { + return types; + } + + const id = getTypeListId(types); + const match = subtypeReductionCache.get(id); + if (match) { + return match; + } + + // We assume that redundant primitive types have already been removed from the types array and that there + // are no any and unknown types in the array. Thus, the only possible supertypes for primitive types are empty + // object types, and if none of those are present we can exclude primitive types from the subtype check. + const hasEmptyObject = hasObjectTypes && some(types, t => !!(t.flags & TypeFlags.Object) && !isGenericMappedType(t) && isEmptyResolvedType(resolveStructuredTypeMembers(t as ObjectType))); + const len = types.length; + let i = len; + let count = 0; + while (i > 0) { + i--; + const source = types[i]; + if (hasEmptyObject || source.flags & TypeFlags.StructuredOrInstantiable) { + // A type parameter with a union constraint may be a subtype of some union, but not a subtype of the + // individual constituents of that union. For example, `T extends A | B` is a subtype of `A | B`, but not + // a subtype of just `A` or just `B`. When we encounter such a type parameter, we therefore check if the + // type parameter is a subtype of a union of all the other types. + if (source.flags & TypeFlags.TypeParameter && getBaseConstraintOrType(source).flags & TypeFlags.Union) { + if (isTypeRelatedTo(source, getUnionType(map(types, t => t === source ? neverType : t)), strictSubtypeRelation)) { + orderedRemoveItemAt(types, i); + } + continue; + } + // Find the first property with a unit type, if any. When constituents have a property by the same name + // but of a different unit type, we can quickly disqualify them from subtype checks. This helps subtype + // reduction of large discriminated union types. + const keyProperty = source.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive) ? + find(getPropertiesOfType(source), p => isUnitType(getTypeOfSymbol(p))) : + undefined; + const keyPropertyType = keyProperty && getRegularTypeOfLiteralType(getTypeOfSymbol(keyProperty)); + for (const target of types) { + if (source !== target) { + if (count === 100000) { + // After 100000 subtype checks we estimate the remaining amount of work by assuming the + // same ratio of checks per element. If the estimated number of remaining type checks is + // greater than 1M we deem the union type too complex to represent. This for example + // caps union types at 1000 unique object types. + const estimatedCount = (count / (len - i)) * len; + if (estimatedCount > 1000000) { + tracing?.instant(tracing.Phase.CheckTypes, "removeSubtypes_DepthLimit", { typeIds: types.map(t => t.id) }); + error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent); + return undefined; + } + } + count++; + if (keyProperty && target.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive)) { + const t = getTypeOfPropertyOfType(target, keyProperty.escapedName); + if (t && isUnitType(t) && getRegularTypeOfLiteralType(t) !== keyPropertyType) { + continue; + } + } + if ( + isTypeRelatedTo(source, target, strictSubtypeRelation) && ( + !(getObjectFlags(getTargetType(source)) & ObjectFlags.Class) || + !(getObjectFlags(getTargetType(target)) & ObjectFlags.Class) || + isTypeDerivedFrom(source, target) + ) + ) { + orderedRemoveItemAt(types, i); + break; + } + } + } + } + } + subtypeReductionCache.set(id, types); + return types; + } + + function removeRedundantLiteralTypes(types: Type[], includes: TypeFlags, reduceVoidUndefined: boolean) { + let i = types.length; + while (i > 0) { + i--; + const t = types[i]; + const flags = t.flags; + const remove = flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && includes & TypeFlags.String || + flags & TypeFlags.NumberLiteral && includes & TypeFlags.Number || + flags & TypeFlags.BigIntLiteral && includes & TypeFlags.BigInt || + flags & TypeFlags.UniqueESSymbol && includes & TypeFlags.ESSymbol || + reduceVoidUndefined && flags & TypeFlags.Undefined && includes & TypeFlags.Void || + isFreshLiteralType(t) && containsType(types, (t as LiteralType).regularType); + if (remove) { + orderedRemoveItemAt(types, i); + } + } + } + + function removeStringLiteralsMatchedByTemplateLiterals(types: Type[]) { + const templates = filter(types, isPatternLiteralType) as (TemplateLiteralType | StringMappingType)[]; + if (templates.length) { + let i = types.length; + while (i > 0) { + i--; + const t = types[i]; + if (t.flags & TypeFlags.StringLiteral && some(templates, template => isTypeMatchedByTemplateLiteralOrStringMapping(t, template))) { + orderedRemoveItemAt(types, i); + } + } + } + } + + function isTypeMatchedByTemplateLiteralOrStringMapping(type: Type, template: TemplateLiteralType | StringMappingType) { + return template.flags & TypeFlags.TemplateLiteral ? + isTypeMatchedByTemplateLiteralType(type, template as TemplateLiteralType) : + isMemberOfStringMapping(type, template); + } + + function removeConstrainedTypeVariables(types: Type[]) { + const typeVariables: TypeVariable[] = []; + // First collect a list of the type variables occurring in constraining intersections. + for (const type of types) { + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) { + const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1; + pushIfUnique(typeVariables, (type as IntersectionType).types[index]); + } + } + // For each type variable, check if the constraining intersections for that type variable fully + // cover the constraint of the type variable; if so, remove the constraining intersections and + // substitute the type variable. + for (const typeVariable of typeVariables) { + const primitives: Type[] = []; + // First collect the primitive types from the constraining intersections. + for (const type of types) { + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) { + const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1; + if ((type as IntersectionType).types[index] === typeVariable) { + insertType(primitives, (type as IntersectionType).types[1 - index]); + } + } + } + // If every constituent in the type variable's constraint is covered by an intersection of the type + // variable and that constituent, remove those intersections and substitute the type variable. + const constraint = getBaseConstraintOfType(typeVariable)!; + if (everyType(constraint, t => containsType(primitives, t))) { + let i = types.length; + while (i > 0) { + i--; + const type = types[i]; + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) { + const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1; + if ((type as IntersectionType).types[index] === typeVariable && containsType(primitives, (type as IntersectionType).types[1 - index])) { + orderedRemoveItemAt(types, i); + } + } + } + insertType(types, typeVariable); + } + } + } + + function isNamedUnionType(type: Type) { + return !!(type.flags & TypeFlags.Union && (type.aliasSymbol || (type as UnionType).origin)); + } + + function addNamedUnions(namedUnions: Type[], types: readonly Type[]) { + for (const t of types) { + if (t.flags & TypeFlags.Union) { + const origin = (t as UnionType).origin; + if (t.aliasSymbol || origin && !(origin.flags & TypeFlags.Union)) { + pushIfUnique(namedUnions, t); + } + else if (origin && origin.flags & TypeFlags.Union) { + addNamedUnions(namedUnions, (origin as UnionType).types); + } + } + } + } + + function createOriginUnionOrIntersectionType(flags: TypeFlags, types: Type[]) { + const result = createOriginType(flags) as UnionOrIntersectionType; + result.types = types; + return result; + } + + // We sort and deduplicate the constituent types based on object identity. If the subtypeReduction + // flag is specified we also reduce the constituent type set to only include types that aren't subtypes + // of other types. Subtype reduction is expensive for large union types and is possible only when union + // types are known not to circularly reference themselves (as is the case with union types created by + // expression constructs such as array literals and the || and ?: operators). Named types can + // circularly reference themselves and therefore cannot be subtype reduced during their declaration. + // For example, "type Item = string | (() => Item" is a named type that circularly references itself. + function getUnionType(types: readonly Type[], unionReduction: UnionReduction = UnionReduction.Literal, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[], origin?: Type): Type { + if (types.length === 0) { + return neverType; + } + if (types.length === 1) { + return types[0]; + } + // We optimize for the common case of unioning a union type with some other type (such as `undefined`). + if (types.length === 2 && !origin && (types[0].flags & TypeFlags.Union || types[1].flags & TypeFlags.Union)) { + const infix = unionReduction === UnionReduction.None ? "N" : unionReduction === UnionReduction.Subtype ? "S" : "L"; + const index = types[0].id < types[1].id ? 0 : 1; + const id = types[index].id + infix + types[1 - index].id + getAliasId(aliasSymbol, aliasTypeArguments); + let type = unionOfUnionTypes.get(id); + if (!type) { + type = getUnionTypeWorker(types, unionReduction, aliasSymbol, aliasTypeArguments, /*origin*/ undefined); + unionOfUnionTypes.set(id, type); + } + return type; + } + return getUnionTypeWorker(types, unionReduction, aliasSymbol, aliasTypeArguments, origin); + } + + function getUnionTypeWorker(types: readonly Type[], unionReduction: UnionReduction, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined, origin: Type | undefined): Type { + let typeSet: Type[] | undefined = []; + const includes = addTypesToUnion(typeSet, 0 as TypeFlags, types); + if (unionReduction !== UnionReduction.None) { + if (includes & TypeFlags.AnyOrUnknown) { + return includes & TypeFlags.Any ? + includes & TypeFlags.IncludesWildcard ? wildcardType : + includes & TypeFlags.IncludesError ? errorType : anyType : + unknownType; + } + if (includes & TypeFlags.Undefined) { + // If type set contains both undefinedType and missingType, remove missingType + if (typeSet.length >= 2 && typeSet[0] === undefinedType && typeSet[1] === missingType) { + orderedRemoveItemAt(typeSet, 1); + } + } + if (includes & (TypeFlags.Enum | TypeFlags.Literal | TypeFlags.UniqueESSymbol | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || includes & TypeFlags.Void && includes & TypeFlags.Undefined) { + removeRedundantLiteralTypes(typeSet, includes, !!(unionReduction & UnionReduction.Subtype)); + } + if (includes & TypeFlags.StringLiteral && includes & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping)) { + removeStringLiteralsMatchedByTemplateLiterals(typeSet); + } + if (includes & TypeFlags.IncludesConstrainedTypeVariable) { + removeConstrainedTypeVariables(typeSet); + } + if (unionReduction === UnionReduction.Subtype) { + typeSet = removeSubtypes(typeSet, !!(includes & TypeFlags.Object)); + if (!typeSet) { + return errorType; + } + } + if (typeSet.length === 0) { + return includes & TypeFlags.Null ? includes & TypeFlags.IncludesNonWideningType ? nullType : nullWideningType : + includes & TypeFlags.Undefined ? includes & TypeFlags.IncludesNonWideningType ? undefinedType : undefinedWideningType : + neverType; + } + } + if (!origin && includes & TypeFlags.Union) { + const namedUnions: Type[] = []; + addNamedUnions(namedUnions, types); + const reducedTypes: Type[] = []; + for (const t of typeSet) { + if (!some(namedUnions, union => containsType((union as UnionType).types, t))) { + reducedTypes.push(t); + } + } + if (!aliasSymbol && namedUnions.length === 1 && reducedTypes.length === 0) { + return namedUnions[0]; + } + // We create a denormalized origin type only when the union was created from one or more named unions + // (unions with alias symbols or origins) and when there is no overlap between those named unions. + const namedTypesCount = reduceLeft(namedUnions, (sum, union) => sum + (union as UnionType).types.length, 0); + if (namedTypesCount + reducedTypes.length === typeSet.length) { + for (const t of namedUnions) { + insertType(reducedTypes, t); + } + origin = createOriginUnionOrIntersectionType(TypeFlags.Union, reducedTypes); + } + } + const objectFlags = (includes & TypeFlags.NotPrimitiveUnion ? 0 : ObjectFlags.PrimitiveUnion) | + (includes & TypeFlags.Intersection ? ObjectFlags.ContainsIntersections : 0); + return getUnionTypeFromSortedList(typeSet, objectFlags, aliasSymbol, aliasTypeArguments, origin); + } + + function getUnionOrIntersectionTypePredicate(signatures: readonly Signature[], kind: TypeFlags | undefined): TypePredicate | undefined { + let last: TypePredicate | undefined; + const types: Type[] = []; + for (const sig of signatures) { + const pred = getTypePredicateOfSignature(sig); + if (pred) { + // Constituent type predicates must all have matching kinds. We don't create composite type predicates for assertions. + if (pred.kind !== TypePredicateKind.This && pred.kind !== TypePredicateKind.Identifier || last && !typePredicateKindsMatch(last, pred)) { + return undefined; + } + last = pred; + types.push(pred.type); + } + else { + // In composite union signatures we permit and ignore signatures with a return type `false`. + const returnType = kind !== TypeFlags.Intersection ? getReturnTypeOfSignature(sig) : undefined; + if (returnType !== falseType && returnType !== regularFalseType) { + return undefined; + } + } + } + if (!last) { + return undefined; + } + const compositeType = getUnionOrIntersectionType(types, kind); + return createTypePredicate(last.kind, last.parameterName, last.parameterIndex, compositeType); + } + + function typePredicateKindsMatch(a: TypePredicate, b: TypePredicate): boolean { + return a.kind === b.kind && a.parameterIndex === b.parameterIndex; + } + + // This function assumes the constituent type list is sorted and deduplicated. + function getUnionTypeFromSortedList(types: Type[], precomputedObjectFlags: ObjectFlags, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[], origin?: Type): Type { + if (types.length === 0) { + return neverType; + } + if (types.length === 1) { + return types[0]; + } + const typeKey = !origin ? getTypeListId(types) : + origin.flags & TypeFlags.Union ? `|${getTypeListId((origin as UnionType).types)}` : + origin.flags & TypeFlags.Intersection ? `&${getTypeListId((origin as IntersectionType).types)}` : + `#${(origin as IndexType).type.id}|${getTypeListId(types)}`; // origin type id alone is insufficient, as `keyof x` may resolve to multiple WIP values while `x` is still resolving + const id = typeKey + getAliasId(aliasSymbol, aliasTypeArguments); + let type = unionTypes.get(id); + if (!type) { + type = createType(TypeFlags.Union) as UnionType; + type.objectFlags = precomputedObjectFlags | getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable); + type.types = types; + type.origin = origin; + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = aliasTypeArguments; + if (types.length === 2 && types[0].flags & TypeFlags.BooleanLiteral && types[1].flags & TypeFlags.BooleanLiteral) { + type.flags |= TypeFlags.Boolean; + (type as UnionType & IntrinsicType).intrinsicName = "boolean"; + } + unionTypes.set(id, type); + } + return type; + } + + function getTypeFromUnionTypeNode(node: UnionTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const aliasSymbol = getAliasSymbolForTypeNode(node); + links.resolvedType = getUnionType(map(node.types, getTypeFromTypeNode), UnionReduction.Literal, aliasSymbol, getTypeArgumentsForAliasSymbol(aliasSymbol)); + } + return links.resolvedType; + } + + function addTypeToIntersection(typeSet: Map, includes: TypeFlags, type: Type) { + const flags = type.flags; + if (flags & TypeFlags.Intersection) { + return addTypesToIntersection(typeSet, includes, (type as IntersectionType).types); + } + if (isEmptyAnonymousObjectType(type)) { + if (!(includes & TypeFlags.IncludesEmptyObject)) { + includes |= TypeFlags.IncludesEmptyObject; + typeSet.set(type.id.toString(), type); + } + } + else { + if (flags & TypeFlags.AnyOrUnknown) { + if (type === wildcardType) includes |= TypeFlags.IncludesWildcard; + if (isErrorType(type)) includes |= TypeFlags.IncludesError; + } + else if (strictNullChecks || !(flags & TypeFlags.Nullable)) { + if (type === missingType) { + includes |= TypeFlags.IncludesMissingType; + type = undefinedType; + } + if (!typeSet.has(type.id.toString())) { + if (type.flags & TypeFlags.Unit && includes & TypeFlags.Unit) { + // We have seen two distinct unit types which means we should reduce to an + // empty intersection. Adding TypeFlags.NonPrimitive causes that to happen. + includes |= TypeFlags.NonPrimitive; + } + typeSet.set(type.id.toString(), type); + } + } + includes |= flags & TypeFlags.IncludesMask; + } + return includes; + } + + // Add the given types to the given type set. Order is preserved, freshness is removed from literal + // types, duplicates are removed, and nested types of the given kind are flattened into the set. + function addTypesToIntersection(typeSet: Map, includes: TypeFlags, types: readonly Type[]) { + for (const type of types) { + includes = addTypeToIntersection(typeSet, includes, getRegularTypeOfLiteralType(type)); + } + return includes; + } + + function removeRedundantSupertypes(types: Type[], includes: TypeFlags) { + let i = types.length; + while (i > 0) { + i--; + const t = types[i]; + const remove = t.flags & TypeFlags.String && includes & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || + t.flags & TypeFlags.Number && includes & TypeFlags.NumberLiteral || + t.flags & TypeFlags.BigInt && includes & TypeFlags.BigIntLiteral || + t.flags & TypeFlags.ESSymbol && includes & TypeFlags.UniqueESSymbol || + t.flags & TypeFlags.Void && includes & TypeFlags.Undefined || + isEmptyAnonymousObjectType(t) && includes & TypeFlags.DefinitelyNonNullable; + if (remove) { + orderedRemoveItemAt(types, i); + } + } + } + + // Check that the given type has a match in every union. A given type is matched by + // an identical type, and a literal type is additionally matched by its corresponding + // primitive type. + function eachUnionContains(unionTypes: UnionType[], type: Type) { + for (const u of unionTypes) { + if (!containsType(u.types, type)) { + const primitive = type.flags & TypeFlags.StringLiteral ? stringType : + type.flags & (TypeFlags.Enum | TypeFlags.NumberLiteral) ? numberType : + type.flags & TypeFlags.BigIntLiteral ? bigintType : + type.flags & TypeFlags.UniqueESSymbol ? esSymbolType : + undefined; + if (!primitive || !containsType(u.types, primitive)) { + return false; + } + } + } + return true; + } + + /** + * Returns true if the intersection of the template literals and string literals is the empty set, + * for example `get${string}` & "setX", and should reduce to never. + */ + function extractRedundantTemplateLiterals(types: Type[]): boolean { + let i = types.length; + const literals = filter(types, t => !!(t.flags & TypeFlags.StringLiteral)); + while (i > 0) { + i--; + const t = types[i]; + if (!(t.flags & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping))) continue; + for (const t2 of literals) { + if (isTypeSubtypeOf(t2, t)) { + // For example, `get${T}` & "getX" is just "getX", and Lowercase & "foo" is just "foo" + orderedRemoveItemAt(types, i); + break; + } + else if (isPatternLiteralType(t)) { + return true; + } + } + } + return false; + } + + function removeFromEach(types: Type[], flag: TypeFlags) { + for (let i = 0; i < types.length; i++) { + types[i] = filterType(types[i], t => !(t.flags & flag)); + } + } + + // If the given list of types contains more than one union of primitive types, replace the + // first with a union containing an intersection of those primitive types, then remove the + // other unions and return true. Otherwise, do nothing and return false. + function intersectUnionsOfPrimitiveTypes(types: Type[]) { + let unionTypes: UnionType[] | undefined; + const index = findIndex(types, t => !!(getObjectFlags(t) & ObjectFlags.PrimitiveUnion)); + if (index < 0) { + return false; + } + let i = index + 1; + // Remove all but the first union of primitive types and collect them in + // the unionTypes array. + while (i < types.length) { + const t = types[i]; + if (getObjectFlags(t) & ObjectFlags.PrimitiveUnion) { + (unionTypes || (unionTypes = [types[index] as UnionType])).push(t as UnionType); + orderedRemoveItemAt(types, i); + } + else { + i++; + } + } + // Return false if there was only one union of primitive types + if (!unionTypes) { + return false; + } + // We have more than one union of primitive types, now intersect them. For each + // type in each union we check if the type is matched in every union and if so + // we include it in the result. + const checked: Type[] = []; + const result: Type[] = []; + for (const u of unionTypes) { + for (const t of u.types) { + if (insertType(checked, t)) { + if (eachUnionContains(unionTypes, t)) { + insertType(result, t); + } + } + } + } + // Finally replace the first union with the result + types[index] = getUnionTypeFromSortedList(result, ObjectFlags.PrimitiveUnion); + return true; + } + + function createIntersectionType(types: Type[], objectFlags: ObjectFlags, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]) { + const result = createType(TypeFlags.Intersection) as IntersectionType; + result.objectFlags = objectFlags | getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable); + result.types = types; + result.aliasSymbol = aliasSymbol; + result.aliasTypeArguments = aliasTypeArguments; + return result; + } + + // We normalize combinations of intersection and union types based on the distributive property of the '&' + // operator. Specifically, because X & (A | B) is equivalent to X & A | X & B, we can transform intersection + // types with union type constituents into equivalent union types with intersection type constituents and + // effectively ensure that union types are always at the top level in type representations. + // + // We do not perform structural deduplication on intersection types. Intersection types are created only by the & + // type operator and we can't reduce those because we want to support recursive intersection types. For example, + // a type alias of the form "type List = T & { next: List }" cannot be reduced during its declaration. + // Also, unlike union types, the order of the constituent types is preserved in order that overload resolution + // for intersections of types with signatures can be deterministic. + function getIntersectionType(types: readonly Type[], flags = IntersectionFlags.None, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + const typeMembershipMap = new Map(); + const includes = addTypesToIntersection(typeMembershipMap, 0 as TypeFlags, types); + const typeSet: Type[] = arrayFrom(typeMembershipMap.values()); + let objectFlags = ObjectFlags.None; + // An intersection type is considered empty if it contains + // the type never, or + // more than one unit type or, + // an object type and a nullable type (null or undefined), or + // a string-like type and a type known to be non-string-like, or + // a number-like type and a type known to be non-number-like, or + // a symbol-like type and a type known to be non-symbol-like, or + // a void-like type and a type known to be non-void-like, or + // a non-primitive type and a type known to be primitive. + if (includes & TypeFlags.Never) { + return contains(typeSet, silentNeverType) ? silentNeverType : neverType; + } + if ( + strictNullChecks && includes & TypeFlags.Nullable && includes & (TypeFlags.Object | TypeFlags.NonPrimitive | TypeFlags.IncludesEmptyObject) || + includes & TypeFlags.NonPrimitive && includes & (TypeFlags.DisjointDomains & ~TypeFlags.NonPrimitive) || + includes & TypeFlags.StringLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.StringLike) || + includes & TypeFlags.NumberLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.NumberLike) || + includes & TypeFlags.BigIntLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.BigIntLike) || + includes & TypeFlags.ESSymbolLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.ESSymbolLike) || + includes & TypeFlags.VoidLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.VoidLike) + ) { + return neverType; + } + if (includes & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && includes & TypeFlags.StringLiteral && extractRedundantTemplateLiterals(typeSet)) { + return neverType; + } + if (includes & TypeFlags.Any) { + return includes & TypeFlags.IncludesWildcard ? wildcardType : includes & TypeFlags.IncludesError ? errorType : anyType; + } + if (!strictNullChecks && includes & TypeFlags.Nullable) { + return includes & TypeFlags.IncludesEmptyObject ? neverType : includes & TypeFlags.Undefined ? undefinedType : nullType; + } + if ( + includes & TypeFlags.String && includes & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || + includes & TypeFlags.Number && includes & TypeFlags.NumberLiteral || + includes & TypeFlags.BigInt && includes & TypeFlags.BigIntLiteral || + includes & TypeFlags.ESSymbol && includes & TypeFlags.UniqueESSymbol || + includes & TypeFlags.Void && includes & TypeFlags.Undefined || + includes & TypeFlags.IncludesEmptyObject && includes & TypeFlags.DefinitelyNonNullable + ) { + if (!(flags & IntersectionFlags.NoSupertypeReduction)) removeRedundantSupertypes(typeSet, includes); + } + if (includes & TypeFlags.IncludesMissingType) { + typeSet[typeSet.indexOf(undefinedType)] = missingType; + } + if (typeSet.length === 0) { + return unknownType; + } + if (typeSet.length === 1) { + return typeSet[0]; + } + if (typeSet.length === 2 && !(flags & IntersectionFlags.NoConstraintReduction)) { + const typeVarIndex = typeSet[0].flags & TypeFlags.TypeVariable ? 0 : 1; + const typeVariable = typeSet[typeVarIndex]; + const primitiveType = typeSet[1 - typeVarIndex]; + if ( + typeVariable.flags & TypeFlags.TypeVariable && + (primitiveType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive) && !isGenericStringLikeType(primitiveType) || includes & TypeFlags.IncludesEmptyObject) + ) { + // We have an intersection T & P or P & T, where T is a type variable and P is a primitive type, the object type, or {}. + const constraint = getBaseConstraintOfType(typeVariable); + // Check that T's constraint is similarly composed of primitive types, the object type, or {}. + if (constraint && everyType(constraint, t => !!(t.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive)) || isEmptyAnonymousObjectType(t))) { + // If T's constraint is a subtype of P, simply return T. For example, given `T extends "a" | "b"`, + // the intersection `T & string` reduces to just T. + if (isTypeStrictSubtypeOf(constraint, primitiveType)) { + return typeVariable; + } + if (!(constraint.flags & TypeFlags.Union && someType(constraint, c => isTypeStrictSubtypeOf(c, primitiveType)))) { + // No constituent of T's constraint is a subtype of P. If P is also not a subtype of T's constraint, + // then the constraint and P are unrelated, and the intersection reduces to never. For example, given + // `T extends "a" | "b"`, the intersection `T & number` reduces to never. + if (!isTypeStrictSubtypeOf(primitiveType, constraint)) { + return neverType; + } + } + // Some constituent of T's constraint is a subtype of P, or P is a subtype of T's constraint. Thus, + // the intersection further constrains the type variable. For example, given `T extends string | number`, + // the intersection `T & "a"` is marked as a constrained type variable. Likewise, given `T extends "a" | 1`, + // the intersection `T & number` is marked as a constrained type variable. + objectFlags = ObjectFlags.IsConstrainedTypeVariable; + } + } + } + const id = getTypeListId(typeSet) + (flags & IntersectionFlags.NoConstraintReduction ? "*" : getAliasId(aliasSymbol, aliasTypeArguments)); + let result = intersectionTypes.get(id); + if (!result) { + if (includes & TypeFlags.Union) { + if (intersectUnionsOfPrimitiveTypes(typeSet)) { + // When the intersection creates a reduced set (which might mean that *all* union types have + // disappeared), we restart the operation to get a new set of combined flags. Once we have + // reduced we'll never reduce again, so this occurs at most once. + result = getIntersectionType(typeSet, flags, aliasSymbol, aliasTypeArguments); + } + else if (every(typeSet, t => !!(t.flags & TypeFlags.Union && (t as UnionType).types[0].flags & TypeFlags.Undefined))) { + const containedUndefinedType = some(typeSet, containsMissingType) ? missingType : undefinedType; + removeFromEach(typeSet, TypeFlags.Undefined); + result = getUnionType([getIntersectionType(typeSet, flags), containedUndefinedType], UnionReduction.Literal, aliasSymbol, aliasTypeArguments); + } + else if (every(typeSet, t => !!(t.flags & TypeFlags.Union && ((t as UnionType).types[0].flags & TypeFlags.Null || (t as UnionType).types[1].flags & TypeFlags.Null)))) { + removeFromEach(typeSet, TypeFlags.Null); + result = getUnionType([getIntersectionType(typeSet, flags), nullType], UnionReduction.Literal, aliasSymbol, aliasTypeArguments); + } + else if (typeSet.length >= 4) { + // When we have four or more constituents, some of which are unions, we employ a "divide and conquer" strategy + // where A & B & C & D is processed as (A & B) & (C & D). Since intersections of unions often produce far smaller + // unions of intersections than the full cartesian product (due to some intersections becoming `never`), this can + // dramatically reduce the overall work. + const middle = Math.floor(typeSet.length / 2); + result = getIntersectionType([getIntersectionType(typeSet.slice(0, middle), flags), getIntersectionType(typeSet.slice(middle), flags)], flags, aliasSymbol, aliasTypeArguments); + } + else { + // We are attempting to construct a type of the form X & (A | B) & (C | D). Transform this into a type of + // the form X & A & C | X & A & D | X & B & C | X & B & D. If the estimated size of the resulting union type + // exceeds 100000 constituents, report an error. + if (!checkCrossProductUnion(typeSet)) { + return errorType; + } + const constituents = getCrossProductIntersections(typeSet, flags); + // We attach a denormalized origin type when at least one constituent of the cross-product union is an + // intersection (i.e. when the intersection didn't just reduce one or more unions to smaller unions) and + // the denormalized origin has fewer constituents than the union itself. + const origin = some(constituents, t => !!(t.flags & TypeFlags.Intersection)) && getConstituentCountOfTypes(constituents) > getConstituentCountOfTypes(typeSet) ? createOriginUnionOrIntersectionType(TypeFlags.Intersection, typeSet) : undefined; + result = getUnionType(constituents, UnionReduction.Literal, aliasSymbol, aliasTypeArguments, origin); + } + } + else { + result = createIntersectionType(typeSet, objectFlags, aliasSymbol, aliasTypeArguments); + } + intersectionTypes.set(id, result); + } + return result; + } + + function getCrossProductUnionSize(types: readonly Type[]) { + return reduceLeft(types, (n, t) => t.flags & TypeFlags.Union ? n * (t as UnionType).types.length : t.flags & TypeFlags.Never ? 0 : n, 1); + } + + function checkCrossProductUnion(types: readonly Type[]) { + const size = getCrossProductUnionSize(types); + if (size >= 100000) { + tracing?.instant(tracing.Phase.CheckTypes, "checkCrossProductUnion_DepthLimit", { typeIds: types.map(t => t.id), size }); + error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent); + return false; + } + return true; + } + + function getCrossProductIntersections(types: readonly Type[], flags: IntersectionFlags) { + const count = getCrossProductUnionSize(types); + const intersections: Type[] = []; + for (let i = 0; i < count; i++) { + const constituents = types.slice(); + let n = i; + for (let j = types.length - 1; j >= 0; j--) { + if (types[j].flags & TypeFlags.Union) { + const sourceTypes = (types[j] as UnionType).types; + const length = sourceTypes.length; + constituents[j] = sourceTypes[n % length]; + n = Math.floor(n / length); + } + } + const t = getIntersectionType(constituents, flags); + if (!(t.flags & TypeFlags.Never)) intersections.push(t); + } + return intersections; + } + + function getConstituentCount(type: Type): number { + return !(type.flags & TypeFlags.UnionOrIntersection) || type.aliasSymbol ? 1 : + type.flags & TypeFlags.Union && (type as UnionType).origin ? getConstituentCount((type as UnionType).origin!) : + getConstituentCountOfTypes((type as UnionOrIntersectionType).types); + } + + function getConstituentCountOfTypes(types: Type[]): number { + return reduceLeft(types, (n, t) => n + getConstituentCount(t), 0); + } + + function getTypeFromIntersectionTypeNode(node: IntersectionTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const aliasSymbol = getAliasSymbolForTypeNode(node); + const types = map(node.types, getTypeFromTypeNode); + // We perform no supertype reduction for X & {} or {} & X, where X is one of string, number, bigint, + // or a pattern literal template type. This enables union types like "a" | "b" | string & {} or + // "aa" | "ab" | `a${string}` which preserve the literal types for purposes of statement completion. + const emptyIndex = types.length === 2 ? types.indexOf(emptyTypeLiteralType) : -1; + const t = emptyIndex >= 0 ? types[1 - emptyIndex] : unknownType; + const noSupertypeReduction = !!(t.flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt) || t.flags & TypeFlags.TemplateLiteral && isPatternLiteralType(t)); + links.resolvedType = getIntersectionType(types, noSupertypeReduction ? IntersectionFlags.NoSupertypeReduction : 0, aliasSymbol, getTypeArgumentsForAliasSymbol(aliasSymbol)); + } + return links.resolvedType; + } + + function createIndexType(type: InstantiableType | UnionOrIntersectionType, indexFlags: IndexFlags) { + const result = createType(TypeFlags.Index) as IndexType; + result.type = type; + result.indexFlags = indexFlags; + return result; + } + + function createOriginIndexType(type: InstantiableType | UnionOrIntersectionType) { + const result = createOriginType(TypeFlags.Index) as IndexType; + result.type = type; + return result; + } + + function getIndexTypeForGenericType(type: InstantiableType | UnionOrIntersectionType, indexFlags: IndexFlags) { + return indexFlags & IndexFlags.StringsOnly ? + type.resolvedStringIndexType || (type.resolvedStringIndexType = createIndexType(type, IndexFlags.StringsOnly)) : + type.resolvedIndexType || (type.resolvedIndexType = createIndexType(type, IndexFlags.None)); + } + + /** + * This roughly mirrors `resolveMappedTypeMembers` in the nongeneric case, except only reports a union of the keys calculated, + * rather than manufacturing the properties. We can't just fetch the `constraintType` since that would ignore mappings + * and mapping the `constraintType` directly ignores how mapped types map _properties_ and not keys (thus ignoring subtype + * reduction in the constraintType) when possible. + * @param noIndexSignatures Indicates if _string_ index signatures should be elided. (other index signatures are always reported) + */ + function getIndexTypeForMappedType(type: MappedType, indexFlags: IndexFlags) { + const typeParameter = getTypeParameterFromMappedType(type); + const constraintType = getConstraintTypeFromMappedType(type); + const nameType = getNameTypeFromMappedType(type.target as MappedType || type); + if (!nameType && !(indexFlags & IndexFlags.NoIndexSignatures)) { + // no mapping and no filtering required, just quickly bail to returning the constraint in the common case + return constraintType; + } + const keyTypes: Type[] = []; + // Calling getApparentType on the `T` of a `keyof T` in the constraint type of a generic mapped type can + // trigger a circularity. For example, `T extends { [P in keyof T & string as Captitalize

]: any }` is + // a circular definition. For this reason, we only eagerly manifest the keys if the constraint is non-generic. + if (isGenericIndexType(constraintType)) { + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // We have a generic index and a homomorphic mapping (but a distributive key remapping) - we need to defer + // the whole `keyof whatever` for later since it's not safe to resolve the shape of modifier type. + return getIndexTypeForGenericType(type, indexFlags); + } + // Include the generic component in the resulting type. + forEachType(constraintType, addMemberForKeyType); + } + else if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + const modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T' + forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(modifiersType, TypeFlags.StringOrNumberLiteralOrUnique, !!(indexFlags & IndexFlags.StringsOnly), addMemberForKeyType); + } + else { + forEachType(getLowerBoundOfKeyType(constraintType), addMemberForKeyType); + } + // We had to pick apart the constraintType to potentially map/filter it - compare the final resulting list with the + // original constraintType, so we can return the union that preserves aliases/origin data if possible. + const result = indexFlags & IndexFlags.NoIndexSignatures ? filterType(getUnionType(keyTypes), t => !(t.flags & (TypeFlags.Any | TypeFlags.String))) : getUnionType(keyTypes); + if (result.flags & TypeFlags.Union && constraintType.flags & TypeFlags.Union && getTypeListId((result as UnionType).types) === getTypeListId((constraintType as UnionType).types)) { + return constraintType; + } + return result; + + function addMemberForKeyType(keyType: Type) { + const propNameType = nameType ? instantiateType(nameType, appendTypeMapping(type.mapper, typeParameter, keyType)) : keyType; + // `keyof` currently always returns `string | number` for concrete `string` index signatures - the below ternary keeps that behavior for mapped types + // See `getLiteralTypeFromProperties` where there's a similar ternary to cause the same behavior. + keyTypes.push(propNameType === stringType ? stringOrNumberType : propNameType); + } + } + + // Ordinarily we reduce a keyof M, where M is a mapped type { [P in K as N

]: X }, to simply N. This however presumes + // that N distributes over union types, i.e. that N is equivalent to N | N | N. Specifically, we only + // want to perform the reduction when the name type of a mapped type is distributive with respect to the type variable + // introduced by the 'in' clause of the mapped type. Note that non-generic types are considered to be distributive because + // they're the same type regardless of what's being distributed over. + function hasDistributiveNameType(mappedType: MappedType) { + const typeVariable = getTypeParameterFromMappedType(mappedType); + return isDistributive(getNameTypeFromMappedType(mappedType) || typeVariable); + function isDistributive(type: Type): boolean { + return type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Primitive | TypeFlags.Never | TypeFlags.TypeParameter | TypeFlags.Object | TypeFlags.NonPrimitive) ? true : + type.flags & TypeFlags.Conditional ? (type as ConditionalType).root.isDistributive && (type as ConditionalType).checkType === typeVariable : + type.flags & (TypeFlags.UnionOrIntersection | TypeFlags.TemplateLiteral) ? every((type as UnionOrIntersectionType | TemplateLiteralType).types, isDistributive) : + type.flags & TypeFlags.IndexedAccess ? isDistributive((type as IndexedAccessType).objectType) && isDistributive((type as IndexedAccessType).indexType) : + type.flags & TypeFlags.Substitution ? isDistributive((type as SubstitutionType).baseType) && isDistributive((type as SubstitutionType).constraint) : + type.flags & TypeFlags.StringMapping ? isDistributive((type as StringMappingType).type) : + false; + } + } + + function getLiteralTypeFromPropertyName(name: PropertyName | JsxAttributeName) { + if (isPrivateIdentifier(name)) { + return neverType; + } + if (isNumericLiteral(name)) { + return getRegularTypeOfLiteralType(checkExpression(name)); + } + if (isComputedPropertyName(name)) { + return getRegularTypeOfLiteralType(checkComputedPropertyName(name)); + } + const propertyName = getPropertyNameForPropertyNameNode(name); + if (propertyName !== undefined) { + return getStringLiteralType(unescapeLeadingUnderscores(propertyName)); + } + if (isExpression(name)) { + return getRegularTypeOfLiteralType(checkExpression(name)); + } + return neverType; + } + + function getLiteralTypeFromProperty(prop: Symbol, include: TypeFlags, includeNonPublic?: boolean) { + if (includeNonPublic || !(getDeclarationModifierFlagsFromSymbol(prop) & ModifierFlags.NonPublicAccessibilityModifier)) { + let type = getSymbolLinks(getLateBoundSymbol(prop)).nameType; + if (!type) { + const name = getNameOfDeclaration(prop.valueDeclaration) as PropertyName | JsxAttributeName; + type = prop.escapedName === InternalSymbolName.Default ? getStringLiteralType("default") : + name && getLiteralTypeFromPropertyName(name) || (!isKnownSymbol(prop) ? getStringLiteralType(symbolName(prop)) : undefined); + } + if (type && type.flags & include) { + return type; + } + } + return neverType; + } + + function isKeyTypeIncluded(keyType: Type, include: TypeFlags): boolean { + return !!(keyType.flags & include || keyType.flags & TypeFlags.Intersection && some((keyType as IntersectionType).types, t => isKeyTypeIncluded(t, include))); + } + + function getLiteralTypeFromProperties(type: Type, include: TypeFlags, includeOrigin: boolean) { + const origin = includeOrigin && (getObjectFlags(type) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference) || type.aliasSymbol) ? createOriginIndexType(type) : undefined; + const propertyTypes = map(getPropertiesOfType(type), prop => getLiteralTypeFromProperty(prop, include)); + const indexKeyTypes = map(getIndexInfosOfType(type), info => + info !== enumNumberIndexInfo && isKeyTypeIncluded(info.keyType, include) ? + info.keyType === stringType && include & TypeFlags.Number ? stringOrNumberType : info.keyType : neverType); + return getUnionType(concatenate(propertyTypes, indexKeyTypes), UnionReduction.Literal, /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined, origin); + } + + function shouldDeferIndexType(type: Type, indexFlags = IndexFlags.None) { + return !!(type.flags & TypeFlags.InstantiableNonPrimitive || + isGenericTupleType(type) || + isGenericMappedType(type) && (!hasDistributiveNameType(type) || getMappedTypeNameTypeKind(type) === MappedTypeNameTypeKind.Remapping) || + type.flags & TypeFlags.Union && !(indexFlags & IndexFlags.NoReducibleCheck) && isGenericReducibleType(type) || + type.flags & TypeFlags.Intersection && maybeTypeOfKind(type, TypeFlags.Instantiable) && some((type as IntersectionType).types, isEmptyAnonymousObjectType)); + } + + function getIndexType(type: Type, indexFlags = IndexFlags.None): Type { + type = getReducedType(type); + return isNoInferType(type) ? getNoInferType(getIndexType((type as SubstitutionType).baseType, indexFlags)) : + shouldDeferIndexType(type, indexFlags) ? getIndexTypeForGenericType(type as InstantiableType | UnionOrIntersectionType, indexFlags) : + type.flags & TypeFlags.Union ? getIntersectionType(map((type as UnionType).types, t => getIndexType(t, indexFlags))) : + type.flags & TypeFlags.Intersection ? getUnionType(map((type as IntersectionType).types, t => getIndexType(t, indexFlags))) : + getObjectFlags(type) & ObjectFlags.Mapped ? getIndexTypeForMappedType(type as MappedType, indexFlags) : + type === wildcardType ? wildcardType : + type.flags & TypeFlags.Unknown ? neverType : + type.flags & (TypeFlags.Any | TypeFlags.Never) ? stringNumberSymbolType : + getLiteralTypeFromProperties(type, (indexFlags & IndexFlags.NoIndexSignatures ? TypeFlags.StringLiteral : TypeFlags.StringLike) | (indexFlags & IndexFlags.StringsOnly ? 0 : TypeFlags.NumberLike | TypeFlags.ESSymbolLike), indexFlags === IndexFlags.None); + } + + function getExtractStringType(type: Type) { + const extractTypeAlias = getGlobalExtractSymbol(); + return extractTypeAlias ? getTypeAliasInstantiation(extractTypeAlias, [type, stringType]) : stringType; + } + + function getIndexTypeOrString(type: Type): Type { + const indexType = getExtractStringType(getIndexType(type)); + return indexType.flags & TypeFlags.Never ? stringType : indexType; + } + + function getTypeFromTypeOperatorNode(node: TypeOperatorNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + switch (node.operator) { + case SyntaxKind.KeyOfKeyword: + links.resolvedType = getIndexType(getTypeFromTypeNode(node.type)); + break; + case SyntaxKind.UniqueKeyword: + links.resolvedType = node.type.kind === SyntaxKind.SymbolKeyword + ? getESSymbolLikeTypeForNode(walkUpParenthesizedTypes(node.parent)) + : errorType; + break; + case SyntaxKind.ReadonlyKeyword: + links.resolvedType = getTypeFromTypeNode(node.type); + break; + default: + Debug.assertNever(node.operator); + } + } + return links.resolvedType; + } + + function getTypeFromTemplateTypeNode(node: TemplateLiteralTypeNode) { + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getTemplateLiteralType( + [node.head.text, ...map(node.templateSpans, span => span.literal.text)], + map(node.templateSpans, span => getTypeFromTypeNode(span.type)), + ); + } + return links.resolvedType; + } + + function getTemplateLiteralType(texts: readonly string[], types: readonly Type[]): Type { + const unionIndex = findIndex(types, t => !!(t.flags & (TypeFlags.Never | TypeFlags.Union))); + if (unionIndex >= 0) { + return checkCrossProductUnion(types) ? + mapType(types[unionIndex], t => getTemplateLiteralType(texts, replaceElement(types, unionIndex, t))) : + errorType; + } + if (contains(types, wildcardType)) { + return wildcardType; + } + const newTypes: Type[] = []; + const newTexts: string[] = []; + let text = texts[0]; + if (!addSpans(texts, types)) { + return stringType; + } + if (newTypes.length === 0) { + return getStringLiteralType(text); + } + newTexts.push(text); + if (every(newTexts, t => t === "")) { + if (every(newTypes, t => !!(t.flags & TypeFlags.String))) { + return stringType; + } + // Normalize `${Mapping}` into Mapping + if (newTypes.length === 1 && isPatternLiteralType(newTypes[0])) { + return newTypes[0]; + } + } + const id = `${getTypeListId(newTypes)}|${map(newTexts, t => t.length).join(",")}|${newTexts.join("")}`; + let type = templateLiteralTypes.get(id); + if (!type) { + templateLiteralTypes.set(id, type = createTemplateLiteralType(newTexts, newTypes)); + } + return type; + + function addSpans(texts: readonly string[], types: readonly Type[]): boolean { + for (let i = 0; i < types.length; i++) { + const t = types[i]; + if (t.flags & (TypeFlags.Literal | TypeFlags.Null | TypeFlags.Undefined)) { + text += getTemplateStringForType(t) || ""; + text += texts[i + 1]; + } + else if (t.flags & TypeFlags.TemplateLiteral) { + text += (t as TemplateLiteralType).texts[0]; + if (!addSpans((t as TemplateLiteralType).texts, (t as TemplateLiteralType).types)) return false; + text += texts[i + 1]; + } + else if (isGenericIndexType(t) || isPatternLiteralPlaceholderType(t)) { + newTypes.push(t); + newTexts.push(text); + text = texts[i + 1]; + } + else { + return false; + } + } + return true; + } + } + + function getTemplateStringForType(type: Type) { + return type.flags & TypeFlags.StringLiteral ? (type as StringLiteralType).value : + type.flags & TypeFlags.NumberLiteral ? "" + (type as NumberLiteralType).value : + type.flags & TypeFlags.BigIntLiteral ? pseudoBigIntToString((type as BigIntLiteralType).value) : + type.flags & (TypeFlags.BooleanLiteral | TypeFlags.Nullable) ? (type as IntrinsicType).intrinsicName : + undefined; + } + + function createTemplateLiteralType(texts: readonly string[], types: readonly Type[]) { + const type = createType(TypeFlags.TemplateLiteral) as TemplateLiteralType; + type.texts = texts; + type.types = types; + return type; + } + + function getStringMappingType(symbol: Symbol, type: Type): Type { + return type.flags & (TypeFlags.Union | TypeFlags.Never) ? mapType(type, t => getStringMappingType(symbol, t)) : + type.flags & TypeFlags.StringLiteral ? getStringLiteralType(applyStringMapping(symbol, (type as StringLiteralType).value)) : + type.flags & TypeFlags.TemplateLiteral ? getTemplateLiteralType(...applyTemplateStringMapping(symbol, (type as TemplateLiteralType).texts, (type as TemplateLiteralType).types)) : + // Mapping> === Mapping + type.flags & TypeFlags.StringMapping && symbol === type.symbol ? type : + type.flags & (TypeFlags.Any | TypeFlags.String | TypeFlags.StringMapping) || isGenericIndexType(type) ? getStringMappingTypeForGenericType(symbol, type) : + // This handles Mapping<`${number}`> and Mapping<`${bigint}`> + isPatternLiteralPlaceholderType(type) ? getStringMappingTypeForGenericType(symbol, getTemplateLiteralType(["", ""], [type])) : + type; + } + + function applyStringMapping(symbol: Symbol, str: string) { + switch (intrinsicTypeKinds.get(symbol.escapedName as string)) { + case IntrinsicTypeKind.Uppercase: + return str.toUpperCase(); + case IntrinsicTypeKind.Lowercase: + return str.toLowerCase(); + case IntrinsicTypeKind.Capitalize: + return str.charAt(0).toUpperCase() + str.slice(1); + case IntrinsicTypeKind.Uncapitalize: + return str.charAt(0).toLowerCase() + str.slice(1); + } + return str; + } + + function applyTemplateStringMapping(symbol: Symbol, texts: readonly string[], types: readonly Type[]): [texts: readonly string[], types: readonly Type[]] { + switch (intrinsicTypeKinds.get(symbol.escapedName as string)) { + case IntrinsicTypeKind.Uppercase: + return [texts.map(t => t.toUpperCase()), types.map(t => getStringMappingType(symbol, t))]; + case IntrinsicTypeKind.Lowercase: + return [texts.map(t => t.toLowerCase()), types.map(t => getStringMappingType(symbol, t))]; + case IntrinsicTypeKind.Capitalize: + return [texts[0] === "" ? texts : [texts[0].charAt(0).toUpperCase() + texts[0].slice(1), ...texts.slice(1)], texts[0] === "" ? [getStringMappingType(symbol, types[0]), ...types.slice(1)] : types]; + case IntrinsicTypeKind.Uncapitalize: + return [texts[0] === "" ? texts : [texts[0].charAt(0).toLowerCase() + texts[0].slice(1), ...texts.slice(1)], texts[0] === "" ? [getStringMappingType(symbol, types[0]), ...types.slice(1)] : types]; + } + return [texts, types]; + } + + function getStringMappingTypeForGenericType(symbol: Symbol, type: Type): Type { + const id = `${getSymbolId(symbol)},${getTypeId(type)}`; + let result = stringMappingTypes.get(id); + if (!result) { + stringMappingTypes.set(id, result = createStringMappingType(symbol, type)); + } + return result; + } + + function createStringMappingType(symbol: Symbol, type: Type) { + const result = createTypeWithSymbol(TypeFlags.StringMapping, symbol) as StringMappingType; + result.type = type; + return result; + } + + function createIndexedAccessType(objectType: Type, indexType: Type, accessFlags: AccessFlags, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { + const type = createType(TypeFlags.IndexedAccess) as IndexedAccessType; + type.objectType = objectType; + type.indexType = indexType; + type.accessFlags = accessFlags; + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = aliasTypeArguments; + return type; + } + + /** + * Returns if a type is or consists of a JSLiteral object type + * In addition to objects which are directly literals, + * * unions where every element is a jsliteral + * * intersections where at least one element is a jsliteral + * * and instantiable types constrained to a jsliteral + * Should all count as literals and not print errors on access or assignment of possibly existing properties. + * This mirrors the behavior of the index signature propagation, to which this behaves similarly (but doesn't affect assignability or inference). + */ + function isJSLiteralType(type: Type): boolean { + if (noImplicitAny) { + return false; // Flag is meaningless under `noImplicitAny` mode + } + if (getObjectFlags(type) & ObjectFlags.JSLiteral) { + return true; + } + if (type.flags & TypeFlags.Union) { + return every((type as UnionType).types, isJSLiteralType); + } + if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, isJSLiteralType); + } + if (type.flags & TypeFlags.Instantiable) { + const constraint = getResolvedBaseConstraint(type); + return constraint !== type && isJSLiteralType(constraint); + } + return false; + } + + function getPropertyNameFromIndex(indexType: Type, accessNode: PropertyName | ObjectBindingPattern | ArrayBindingPattern | IndexedAccessTypeNode | ElementAccessExpression | SyntheticExpression | undefined) { + return isTypeUsableAsPropertyName(indexType) ? + getPropertyNameFromType(indexType) : + accessNode && isPropertyName(accessNode) ? + // late bound names are handled in the first branch, so here we only need to handle normal names + getPropertyNameForPropertyNameNode(accessNode) : + undefined; + } + + function isUncalledFunctionReference(node: Node, symbol: Symbol) { + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method)) { + const parent = findAncestor(node.parent, n => !isAccessExpression(n)) || node.parent; + if (isCallLikeExpression(parent)) { + return isCallOrNewExpression(parent) && isIdentifier(node) && hasMatchingArgument(parent, node); + } + return every(symbol.declarations, d => !isFunctionLike(d) || isDeprecatedDeclaration(d)); + } + return true; + } + + function getPropertyTypeForIndexType(originalObjectType: Type, objectType: Type, indexType: Type, fullIndexType: Type, accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression | undefined, accessFlags: AccessFlags) { + const accessExpression = accessNode && accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode : undefined; + const propName = accessNode && isPrivateIdentifier(accessNode) ? undefined : getPropertyNameFromIndex(indexType, accessNode); + + if (propName !== undefined) { + if (accessFlags & AccessFlags.Contextual) { + return getTypeOfPropertyOfContextualType(objectType, propName) || anyType; + } + const prop = getPropertyOfType(objectType, propName); + if (prop) { + if (accessFlags & AccessFlags.ReportDeprecated && accessNode && prop.declarations && isDeprecatedSymbol(prop) && isUncalledFunctionReference(accessNode, prop)) { + const deprecatedNode = accessExpression?.argumentExpression ?? (isIndexedAccessTypeNode(accessNode) ? accessNode.indexType : accessNode); + addDeprecatedSuggestion(deprecatedNode, prop.declarations, propName as string); + } + if (accessExpression) { + markPropertyAsReferenced(prop, accessExpression, isSelfTypeAccess(accessExpression.expression, objectType.symbol)); + if (isAssignmentToReadonlyEntity(accessExpression, prop, getAssignmentTargetKind(accessExpression))) { + error(accessExpression.argumentExpression, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(prop)); + return undefined; + } + if (accessFlags & AccessFlags.CacheSymbol) { + getNodeLinks(accessNode!).resolvedSymbol = prop; + } + if (isThisPropertyAccessInConstructor(accessExpression, prop)) { + return autoType; + } + } + const propType = accessFlags & AccessFlags.Writing ? getWriteTypeOfSymbol(prop) : getTypeOfSymbol(prop); + return accessExpression && getAssignmentTargetKind(accessExpression) !== AssignmentKind.Definite ? getFlowTypeOfReference(accessExpression, propType) : + accessNode && isIndexedAccessTypeNode(accessNode) && containsMissingType(propType) ? getUnionType([propType, undefinedType]) : + propType; + } + if (everyType(objectType, isTupleType) && isNumericLiteralName(propName)) { + const index = +propName; + if (accessNode && everyType(objectType, t => !((t as TupleTypeReference).target.combinedFlags & ElementFlags.Variable)) && !(accessFlags & AccessFlags.NoTupleBoundsCheck)) { + const indexNode = getIndexNodeForAccessExpression(accessNode); + if (isTupleType(objectType)) { + if (index < 0) { + error(indexNode, Diagnostics.A_tuple_type_cannot_be_indexed_with_a_negative_value); + return undefinedType; + } + error(indexNode, Diagnostics.Tuple_type_0_of_length_1_has_no_element_at_index_2, typeToString(objectType), getTypeReferenceArity(objectType), unescapeLeadingUnderscores(propName)); + } + else { + error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType)); + } + } + if (index >= 0) { + errorIfWritingToReadonlyIndex(getIndexInfoOfType(objectType, numberType)); + return getTupleElementTypeOutOfStartCount(objectType, index, accessFlags & AccessFlags.IncludeUndefined ? missingType : undefined); + } + } + } + if (!(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike)) { + if (objectType.flags & (TypeFlags.Any | TypeFlags.Never)) { + return objectType; + } + // If no index signature is applicable, we default to the string index signature. In effect, this means the string + // index signature applies even when accessing with a symbol-like type. + const indexInfo = getApplicableIndexInfo(objectType, indexType) || getIndexInfoOfType(objectType, stringType); + if (indexInfo) { + if (accessFlags & AccessFlags.NoIndexSignatures && indexInfo.keyType !== numberType) { + if (accessExpression) { + if (accessFlags & AccessFlags.Writing) { + error(accessExpression, Diagnostics.Type_0_is_generic_and_can_only_be_indexed_for_reading, typeToString(originalObjectType)); + } + else { + error(accessExpression, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(originalObjectType)); + } + } + return undefined; + } + if (accessNode && indexInfo.keyType === stringType && !isTypeAssignableToKind(indexType, TypeFlags.String | TypeFlags.Number)) { + const indexNode = getIndexNodeForAccessExpression(accessNode); + error(indexNode, Diagnostics.Type_0_cannot_be_used_as_an_index_type, typeToString(indexType)); + return accessFlags & AccessFlags.IncludeUndefined ? getUnionType([indexInfo.type, missingType]) : indexInfo.type; + } + errorIfWritingToReadonlyIndex(indexInfo); + // When accessing an enum object with its own type, + // e.g. E[E.A] for enum E { A }, undefined shouldn't + // be included in the result type + if ( + (accessFlags & AccessFlags.IncludeUndefined) && + !(objectType.symbol && + objectType.symbol.flags & (SymbolFlags.RegularEnum | SymbolFlags.ConstEnum) && + (indexType.symbol && + indexType.flags & TypeFlags.EnumLiteral && + getParentOfSymbol(indexType.symbol) === objectType.symbol)) + ) { + return getUnionType([indexInfo.type, missingType]); + } + return indexInfo.type; + } + if (indexType.flags & TypeFlags.Never) { + return neverType; + } + if (isJSLiteralType(objectType)) { + return anyType; + } + if (accessExpression && !isConstEnumObjectType(objectType)) { + if (isObjectLiteralType(objectType)) { + if (noImplicitAny && indexType.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) { + diagnostics.add(createDiagnosticForNode(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as StringLiteralType).value, typeToString(objectType))); + return undefinedType; + } + else if (indexType.flags & (TypeFlags.Number | TypeFlags.String)) { + const types = map((objectType as ResolvedType).properties, property => { + return getTypeOfSymbol(property); + }); + return getUnionType(append(types, undefinedType)); + } + } + + if (objectType.symbol === globalThisSymbol && propName !== undefined && globalThisSymbol.exports!.has(propName) && (globalThisSymbol.exports!.get(propName)!.flags & SymbolFlags.BlockScoped)) { + error(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType)); + } + else if (noImplicitAny && !(accessFlags & AccessFlags.SuppressNoImplicitAnyError)) { + if (propName !== undefined && typeHasStaticProperty(propName, objectType)) { + const typeName = typeToString(objectType); + error(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_to_access_the_static_member_2_instead, propName as string, typeName, typeName + "[" + getTextOfNode(accessExpression.argumentExpression) + "]"); + } + else if (getIndexTypeOfType(objectType, numberType)) { + error(accessExpression.argumentExpression, Diagnostics.Element_implicitly_has_an_any_type_because_index_expression_is_not_of_type_number); + } + else { + let suggestion: string | undefined; + if (propName !== undefined && (suggestion = getSuggestionForNonexistentProperty(propName as string, objectType))) { + if (suggestion !== undefined) { + error(accessExpression.argumentExpression, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2, propName as string, typeToString(objectType), suggestion); + } + } + else { + const suggestion = getSuggestionForNonexistentIndexSignature(objectType, accessExpression, indexType); + if (suggestion !== undefined) { + error(accessExpression, Diagnostics.Element_implicitly_has_an_any_type_because_type_0_has_no_index_signature_Did_you_mean_to_call_1, typeToString(objectType), suggestion); + } + else { + let errorInfo: DiagnosticMessageChain | undefined; + if (indexType.flags & TypeFlags.EnumLiteral) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, "[" + typeToString(indexType) + "]", typeToString(objectType)); + } + else if (indexType.flags & TypeFlags.UniqueESSymbol) { + const symbolName = getFullyQualifiedName((indexType as UniqueESSymbolType).symbol, accessExpression); + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, "[" + symbolName + "]", typeToString(objectType)); + } + else if (indexType.flags & TypeFlags.StringLiteral) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as StringLiteralType).value, typeToString(objectType)); + } + else if (indexType.flags & TypeFlags.NumberLiteral) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as NumberLiteralType).value, typeToString(objectType)); + } + else if (indexType.flags & (TypeFlags.Number | TypeFlags.String)) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_index_signature_with_a_parameter_of_type_0_was_found_on_type_1, typeToString(indexType), typeToString(objectType)); + } + + errorInfo = chainDiagnosticMessages( + errorInfo, + Diagnostics.Element_implicitly_has_an_any_type_because_expression_of_type_0_can_t_be_used_to_index_type_1, + typeToString(fullIndexType), + typeToString(objectType), + ); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(accessExpression), accessExpression, errorInfo)); + } + } + } + } + return undefined; + } + } + if (isJSLiteralType(objectType)) { + return anyType; + } + if (accessNode) { + const indexNode = getIndexNodeForAccessExpression(accessNode); + if (indexType.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) { + error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, "" + (indexType as StringLiteralType | NumberLiteralType).value, typeToString(objectType)); + } + else if (indexType.flags & (TypeFlags.String | TypeFlags.Number)) { + error(indexNode, Diagnostics.Type_0_has_no_matching_index_signature_for_type_1, typeToString(objectType), typeToString(indexType)); + } + else { + error(indexNode, Diagnostics.Type_0_cannot_be_used_as_an_index_type, typeToString(indexType)); + } + } + if (isTypeAny(indexType)) { + return indexType; + } + return undefined; + + function errorIfWritingToReadonlyIndex(indexInfo: IndexInfo | undefined): void { + if (indexInfo && indexInfo.isReadonly && accessExpression && (isAssignmentTarget(accessExpression) || isDeleteTarget(accessExpression))) { + error(accessExpression, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType)); + } + } + } + + function getIndexNodeForAccessExpression(accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression) { + return accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode.argumentExpression : + accessNode.kind === SyntaxKind.IndexedAccessType ? accessNode.indexType : + accessNode.kind === SyntaxKind.ComputedPropertyName ? accessNode.expression : + accessNode; + } + + function isPatternLiteralPlaceholderType(type: Type): boolean { + if (type.flags & TypeFlags.Intersection) { + // Return true if the intersection consists of one or more placeholders and zero or + // more object type tags. + let seenPlaceholder = false; + for (const t of (type as IntersectionType).types) { + if (t.flags & (TypeFlags.Literal | TypeFlags.Nullable) || isPatternLiteralPlaceholderType(t)) { + seenPlaceholder = true; + } + else if (!(t.flags & TypeFlags.Object)) { + return false; + } + } + return seenPlaceholder; + } + return !!(type.flags & (TypeFlags.Any | TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt)) || isPatternLiteralType(type); + } + + function isPatternLiteralType(type: Type) { + // A pattern literal type is a template literal or a string mapping type that contains only + // non-generic pattern literal placeholders. + return !!(type.flags & TypeFlags.TemplateLiteral) && every((type as TemplateLiteralType).types, isPatternLiteralPlaceholderType) || + !!(type.flags & TypeFlags.StringMapping) && isPatternLiteralPlaceholderType((type as StringMappingType).type); + } + + function isGenericStringLikeType(type: Type) { + return !!(type.flags & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping)) && !isPatternLiteralType(type); + } + + function isGenericType(type: Type): boolean { + return !!getGenericObjectFlags(type); + } + + function isGenericObjectType(type: Type): boolean { + return !!(getGenericObjectFlags(type) & ObjectFlags.IsGenericObjectType); + } + + function isGenericIndexType(type: Type): boolean { + return !!(getGenericObjectFlags(type) & ObjectFlags.IsGenericIndexType); + } + + function getGenericObjectFlags(type: Type): ObjectFlags { + if (type.flags & (TypeFlags.UnionOrIntersection)) { + if (!((type as UnionOrIntersectionType).objectFlags & ObjectFlags.IsGenericTypeComputed)) { + (type as UnionOrIntersectionType).objectFlags |= ObjectFlags.IsGenericTypeComputed | + reduceLeft((type as UnionOrIntersectionType).types, (flags, t) => flags | getGenericObjectFlags(t), 0); + } + return (type as UnionOrIntersectionType).objectFlags & ObjectFlags.IsGenericType; + } + if (type.flags & TypeFlags.Substitution) { + if (!((type as SubstitutionType).objectFlags & ObjectFlags.IsGenericTypeComputed)) { + (type as SubstitutionType).objectFlags |= ObjectFlags.IsGenericTypeComputed | + getGenericObjectFlags((type as SubstitutionType).baseType) | getGenericObjectFlags((type as SubstitutionType).constraint); + } + return (type as SubstitutionType).objectFlags & ObjectFlags.IsGenericType; + } + return (type.flags & TypeFlags.InstantiableNonPrimitive || isGenericMappedType(type) || isGenericTupleType(type) ? ObjectFlags.IsGenericObjectType : 0) | + (type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.Index) || isGenericStringLikeType(type) ? ObjectFlags.IsGenericIndexType : 0); + } + + function getSimplifiedType(type: Type, writing: boolean): Type { + return type.flags & TypeFlags.IndexedAccess ? getSimplifiedIndexedAccessType(type as IndexedAccessType, writing) : + type.flags & TypeFlags.Conditional ? getSimplifiedConditionalType(type as ConditionalType, writing) : + type; + } + + function distributeIndexOverObjectType(objectType: Type, indexType: Type, writing: boolean) { + // (T | U)[K] -> T[K] | U[K] (reading) + // (T | U)[K] -> T[K] & U[K] (writing) + // (T & U)[K] -> T[K] & U[K] + if (objectType.flags & TypeFlags.Union || objectType.flags & TypeFlags.Intersection && !shouldDeferIndexType(objectType)) { + const types = map((objectType as UnionOrIntersectionType).types, t => getSimplifiedType(getIndexedAccessType(t, indexType), writing)); + return objectType.flags & TypeFlags.Intersection || writing ? getIntersectionType(types) : getUnionType(types); + } + } + + function distributeObjectOverIndexType(objectType: Type, indexType: Type, writing: boolean) { + // T[A | B] -> T[A] | T[B] (reading) + // T[A | B] -> T[A] & T[B] (writing) + if (indexType.flags & TypeFlags.Union) { + const types = map((indexType as UnionType).types, t => getSimplifiedType(getIndexedAccessType(objectType, t), writing)); + return writing ? getIntersectionType(types) : getUnionType(types); + } + } + + // Transform an indexed access to a simpler form, if possible. Return the simpler form, or return + // the type itself if no transformation is possible. The writing flag indicates that the type is + // the target of an assignment. + function getSimplifiedIndexedAccessType(type: IndexedAccessType, writing: boolean): Type { + const cache = writing ? "simplifiedForWriting" : "simplifiedForReading"; + if (type[cache]) { + return type[cache] === circularConstraintType ? type : type[cache]!; + } + type[cache] = circularConstraintType; + // We recursively simplify the object type as it may in turn be an indexed access type. For example, with + // '{ [P in T]: { [Q in U]: number } }[T][U]' we want to first simplify the inner indexed access type. + const objectType = getSimplifiedType(type.objectType, writing); + const indexType = getSimplifiedType(type.indexType, writing); + // T[A | B] -> T[A] | T[B] (reading) + // T[A | B] -> T[A] & T[B] (writing) + const distributedOverIndex = distributeObjectOverIndexType(objectType, indexType, writing); + if (distributedOverIndex) { + return type[cache] = distributedOverIndex; + } + // Only do the inner distributions if the index can no longer be instantiated to cause index distribution again + if (!(indexType.flags & TypeFlags.Instantiable)) { + // (T | U)[K] -> T[K] | U[K] (reading) + // (T | U)[K] -> T[K] & U[K] (writing) + // (T & U)[K] -> T[K] & U[K] + const distributedOverObject = distributeIndexOverObjectType(objectType, indexType, writing); + if (distributedOverObject) { + return type[cache] = distributedOverObject; + } + } + // So ultimately (reading): + // ((A & B) | C)[K1 | K2] -> ((A & B) | C)[K1] | ((A & B) | C)[K2] -> (A & B)[K1] | C[K1] | (A & B)[K2] | C[K2] -> (A[K1] & B[K1]) | C[K1] | (A[K2] & B[K2]) | C[K2] + + // A generic tuple type indexed by a number exists only when the index type doesn't select a + // fixed element. We simplify to either the combined type of all elements (when the index type + // the actual number type) or to the combined type of all non-fixed elements. + if (isGenericTupleType(objectType) && indexType.flags & TypeFlags.NumberLike) { + const elementType = getElementTypeOfSliceOfTupleType(objectType, indexType.flags & TypeFlags.Number ? 0 : objectType.target.fixedLength, /*endSkipCount*/ 0, writing); + if (elementType) { + return type[cache] = elementType; + } + } + // If the object type is a mapped type { [P in K]: E }, where K is generic, or { [P in K as N]: E }, where + // K is generic and N is assignable to P, instantiate E using a mapper that substitutes the index type for P. + // For example, for an index access { [P in K]: Box }[X], we construct the type Box. + if (isGenericMappedType(objectType)) { + if (getMappedTypeNameTypeKind(objectType) !== MappedTypeNameTypeKind.Remapping) { + return type[cache] = mapType(substituteIndexedMappedType(objectType, type.indexType), t => getSimplifiedType(t, writing)); + } + } + return type[cache] = type; + } + + function getSimplifiedConditionalType(type: ConditionalType, writing: boolean) { + const checkType = type.checkType; + const extendsType = type.extendsType; + const trueType = getTrueTypeFromConditionalType(type); + const falseType = getFalseTypeFromConditionalType(type); + // Simplifications for types of the form `T extends U ? T : never` and `T extends U ? never : T`. + if (falseType.flags & TypeFlags.Never && getActualTypeVariable(trueType) === getActualTypeVariable(checkType)) { + if (checkType.flags & TypeFlags.Any || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true + return getSimplifiedType(trueType, writing); + } + else if (isIntersectionEmpty(checkType, extendsType)) { // Always false + return neverType; + } + } + else if (trueType.flags & TypeFlags.Never && getActualTypeVariable(falseType) === getActualTypeVariable(checkType)) { + if (!(checkType.flags & TypeFlags.Any) && isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true + return neverType; + } + else if (checkType.flags & TypeFlags.Any || isIntersectionEmpty(checkType, extendsType)) { // Always false + return getSimplifiedType(falseType, writing); + } + } + return type; + } + + /** + * Invokes union simplification logic to determine if an intersection is considered empty as a union constituent + */ + function isIntersectionEmpty(type1: Type, type2: Type) { + return !!(getUnionType([intersectTypes(type1, type2), neverType]).flags & TypeFlags.Never); + } + + // Given an indexed access on a mapped type of the form { [P in K]: E }[X], return an instantiation of E where P is + // replaced with X. Since this simplification doesn't account for mapped type modifiers, add 'undefined' to the + // resulting type if the mapped type includes a '?' modifier or if the modifiers type indicates that some properties + // are optional. If the modifiers type is generic, conservatively estimate optionality by recursively looking for + // mapped types that include '?' modifiers. + function substituteIndexedMappedType(objectType: MappedType, index: Type) { + const mapper = createTypeMapper([getTypeParameterFromMappedType(objectType)], [index]); + const templateMapper = combineTypeMappers(objectType.mapper, mapper); + const instantiatedTemplateType = instantiateType(getTemplateTypeFromMappedType(objectType.target as MappedType || objectType), templateMapper); + const isOptional = getMappedTypeOptionality(objectType) > 0 || (isGenericType(objectType) ? + getCombinedMappedTypeOptionality(getModifiersTypeFromMappedType(objectType)) > 0 : + couldAccessOptionalProperty(objectType, index)); + return addOptionality(instantiatedTemplateType, /*isProperty*/ true, isOptional); + } + + // Return true if an indexed access with the given object and index types could access an optional property. + function couldAccessOptionalProperty(objectType: Type, indexType: Type) { + const indexConstraint = getBaseConstraintOfType(indexType); + return !!indexConstraint && some(getPropertiesOfType(objectType), p => + !!(p.flags & SymbolFlags.Optional) && + isTypeAssignableTo(getLiteralTypeFromProperty(p, TypeFlags.StringOrNumberLiteralOrUnique), indexConstraint)); + } + + function getIndexedAccessType(objectType: Type, indexType: Type, accessFlags = AccessFlags.None, accessNode?: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + return getIndexedAccessTypeOrUndefined(objectType, indexType, accessFlags, accessNode, aliasSymbol, aliasTypeArguments) || (accessNode ? errorType : unknownType); + } + + function indexTypeLessThan(indexType: Type, limit: number) { + return everyType(indexType, t => { + if (t.flags & TypeFlags.StringOrNumberLiteral) { + const propName = getPropertyNameFromType(t as StringLiteralType | NumberLiteralType); + if (isNumericLiteralName(propName)) { + const index = +propName; + return index >= 0 && index < limit; + } + } + return false; + }); + } + + function getIndexedAccessTypeOrUndefined(objectType: Type, indexType: Type, accessFlags = AccessFlags.None, accessNode?: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type | undefined { + if (objectType === wildcardType || indexType === wildcardType) { + return wildcardType; + } + objectType = getReducedType(objectType); + // If the object type has a string index signature and no other members we know that the result will + // always be the type of that index signature and we can simplify accordingly. + if (isStringIndexSignatureOnlyType(objectType) && !(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.String | TypeFlags.Number)) { + indexType = stringType; + } + // In noUncheckedIndexedAccess mode, indexed access operations that occur in an expression in a read position and resolve to + // an index signature have 'undefined' included in their type. + if (compilerOptions.noUncheckedIndexedAccess && accessFlags & AccessFlags.ExpressionPosition) accessFlags |= AccessFlags.IncludeUndefined; + // If the index type is generic, or if the object type is generic and doesn't originate in an expression and + // the operation isn't exclusively indexing the fixed (non-variadic) portion of a tuple type, we are performing + // a higher-order index access where we cannot meaningfully access the properties of the object type. Note that + // for a generic T and a non-generic K, we eagerly resolve T[K] if it originates in an expression. This is to + // preserve backwards compatibility. For example, an element access 'this["foo"]' has always been resolved + // eagerly using the constraint type of 'this' at the given location. + if ( + isGenericIndexType(indexType) || (accessNode && accessNode.kind !== SyntaxKind.IndexedAccessType ? + isGenericTupleType(objectType) && !indexTypeLessThan(indexType, getTotalFixedElementCount(objectType.target)) : + isGenericObjectType(objectType) && !(isTupleType(objectType) && indexTypeLessThan(indexType, getTotalFixedElementCount(objectType.target))) || isGenericReducibleType(objectType)) + ) { + if (objectType.flags & TypeFlags.AnyOrUnknown) { + return objectType; + } + // Defer the operation by creating an indexed access type. + const persistentAccessFlags = accessFlags & AccessFlags.Persistent; + const id = objectType.id + "," + indexType.id + "," + persistentAccessFlags + getAliasId(aliasSymbol, aliasTypeArguments); + let type = indexedAccessTypes.get(id); + if (!type) { + indexedAccessTypes.set(id, type = createIndexedAccessType(objectType, indexType, persistentAccessFlags, aliasSymbol, aliasTypeArguments)); + } + + return type; + } + // In the following we resolve T[K] to the type of the property in T selected by K. + // We treat boolean as different from other unions to improve errors; + // skipping straight to getPropertyTypeForIndexType gives errors with 'boolean' instead of 'true'. + const apparentObjectType = getReducedApparentType(objectType); + if (indexType.flags & TypeFlags.Union && !(indexType.flags & TypeFlags.Boolean)) { + const propTypes: Type[] = []; + let wasMissingProp = false; + for (const t of (indexType as UnionType).types) { + const propType = getPropertyTypeForIndexType(objectType, apparentObjectType, t, indexType, accessNode, accessFlags | (wasMissingProp ? AccessFlags.SuppressNoImplicitAnyError : 0)); + if (propType) { + propTypes.push(propType); + } + else if (!accessNode) { + // If there's no error node, we can immeditely stop, since error reporting is off + return undefined; + } + else { + // Otherwise we set a flag and return at the end of the loop so we still mark all errors + wasMissingProp = true; + } + } + if (wasMissingProp) { + return undefined; + } + return accessFlags & AccessFlags.Writing + ? getIntersectionType(propTypes, IntersectionFlags.None, aliasSymbol, aliasTypeArguments) + : getUnionType(propTypes, UnionReduction.Literal, aliasSymbol, aliasTypeArguments); + } + return getPropertyTypeForIndexType(objectType, apparentObjectType, indexType, indexType, accessNode, accessFlags | AccessFlags.CacheSymbol | AccessFlags.ReportDeprecated); + } + + function getTypeFromIndexedAccessTypeNode(node: IndexedAccessTypeNode) { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const objectType = getTypeFromTypeNode(node.objectType); + const indexType = getTypeFromTypeNode(node.indexType); + const potentialAlias = getAliasSymbolForTypeNode(node); + links.resolvedType = getIndexedAccessType(objectType, indexType, AccessFlags.None, node, potentialAlias, getTypeArgumentsForAliasSymbol(potentialAlias)); + } + return links.resolvedType; + } + + function getTypeFromMappedTypeNode(node: MappedTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const type = createObjectType(ObjectFlags.Mapped, node.symbol) as MappedType; + type.declaration = node; + type.aliasSymbol = getAliasSymbolForTypeNode(node); + type.aliasTypeArguments = getTypeArgumentsForAliasSymbol(type.aliasSymbol); + links.resolvedType = type; + // Eagerly resolve the constraint type which forces an error if the constraint type circularly + // references itself through one or more type aliases. + getConstraintTypeFromMappedType(type); + } + return links.resolvedType; + } + + function getActualTypeVariable(type: Type): Type { + if (type.flags & TypeFlags.Substitution) { + return getActualTypeVariable((type as SubstitutionType).baseType); + } + if ( + type.flags & TypeFlags.IndexedAccess && ( + (type as IndexedAccessType).objectType.flags & TypeFlags.Substitution || + (type as IndexedAccessType).indexType.flags & TypeFlags.Substitution + ) + ) { + return getIndexedAccessType(getActualTypeVariable((type as IndexedAccessType).objectType), getActualTypeVariable((type as IndexedAccessType).indexType)); + } + return type; + } + + function isSimpleTupleType(node: TypeNode): boolean { + return isTupleTypeNode(node) && length(node.elements) > 0 && + !some(node.elements, e => isOptionalTypeNode(e) || isRestTypeNode(e) || isNamedTupleMember(e) && !!(e.questionToken || e.dotDotDotToken)); + } + + function isDeferredType(type: Type, checkTuples: boolean) { + return isGenericType(type) || checkTuples && isTupleType(type) && some(getElementTypes(type), isGenericType); + } + + function getConditionalType(root: ConditionalRoot, mapper: TypeMapper | undefined, forConstraint: boolean, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + let result; + let extraTypes: Type[] | undefined; + let tailCount = 0; + // We loop here for an immediately nested conditional type in the false position, effectively treating + // types of the form 'A extends B ? X : C extends D ? Y : E extends F ? Z : ...' as a single construct for + // purposes of resolution. We also loop here when resolution of a conditional type ends in resolution of + // another (or, through recursion, possibly the same) conditional type. In the potentially tail-recursive + // cases we increment the tail recursion counter and stop after 1000 iterations. + while (true) { + if (tailCount === 1000) { + error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite); + return errorType; + } + const checkType = instantiateType(getActualTypeVariable(root.checkType), mapper); + const extendsType = instantiateType(root.extendsType, mapper); + if (checkType === errorType || extendsType === errorType) { + return errorType; + } + if (checkType === wildcardType || extendsType === wildcardType) { + return wildcardType; + } + const checkTypeNode = skipTypeParentheses(root.node.checkType); + const extendsTypeNode = skipTypeParentheses(root.node.extendsType); + // When the check and extends types are simple tuple types of the same arity, we defer resolution of the + // conditional type when any tuple elements are generic. This is such that non-distributable conditional + // types can be written `[X] extends [Y] ? ...` and be deferred similarly to `X extends Y ? ...`. + const checkTuples = isSimpleTupleType(checkTypeNode) && isSimpleTupleType(extendsTypeNode) && + length((checkTypeNode as TupleTypeNode).elements) === length((extendsTypeNode as TupleTypeNode).elements); + const checkTypeDeferred = isDeferredType(checkType, checkTuples); + let combinedMapper: TypeMapper | undefined; + if (root.inferTypeParameters) { + // When we're looking at making an inference for an infer type, when we get its constraint, it'll automagically be + // instantiated with the context, so it doesn't need the mapper for the inference context - however the constraint + // may refer to another _root_, _uncloned_ `infer` type parameter [1], or to something mapped by `mapper` [2]. + // [1] Eg, if we have `Foo` and `Foo` - `B` is constrained to `T`, which, in turn, has been instantiated + // as `number` + // Conversely, if we have `Foo`, `B` is still constrained to `T` and `T` is instantiated as `A` + // [2] Eg, if we have `Foo` and `Foo` where `Q` is mapped by `mapper` into `number` - `B` is constrained to `T` + // which is in turn instantiated as `Q`, which is in turn instantiated as `number`. + // So we need to: + // * combine `context.nonFixingMapper` with `mapper` so their constraints can be instantiated in the context of `mapper` (otherwise they'd only get inference context information) + // * incorporate all of the component mappers into the combined mapper for the true and false members + // This means we have two mappers that need applying: + // * The original `mapper` used to create this conditional + // * The mapper that maps the infer type parameter to its inference result (`context.mapper`) + const context = createInferenceContext(root.inferTypeParameters, /*signature*/ undefined, InferenceFlags.None); + if (mapper) { + context.nonFixingMapper = combineTypeMappers(context.nonFixingMapper, mapper); + } + if (!checkTypeDeferred) { + // We don't want inferences from constraints as they may cause us to eagerly resolve the + // conditional type instead of deferring resolution. Also, we always want strict function + // types rules (i.e. proper contravariance) for inferences. + inferTypes(context.inferences, checkType, extendsType, InferencePriority.NoConstraints | InferencePriority.AlwaysStrict); + } + // It's possible for 'infer T' type paramteters to be given uninstantiated constraints when the + // those type parameters are used in type references (see getInferredTypeParameterConstraint). For + // that reason we need context.mapper to be first in the combined mapper. See #42636 for examples. + combinedMapper = mapper ? combineTypeMappers(context.mapper, mapper) : context.mapper; + } + // Instantiate the extends type including inferences for 'infer T' type parameters + const inferredExtendsType = combinedMapper ? instantiateType(root.extendsType, combinedMapper) : extendsType; + // We attempt to resolve the conditional type only when the check and extends types are non-generic + if (!checkTypeDeferred && !isDeferredType(inferredExtendsType, checkTuples)) { + // Return falseType for a definitely false extends check. We check an instantiations of the two + // types with type parameters mapped to the wildcard type, the most permissive instantiations + // possible (the wildcard type is assignable to and from all types). If those are not related, + // then no instantiations will be and we can just return the false branch type. + if (!(inferredExtendsType.flags & TypeFlags.AnyOrUnknown) && (checkType.flags & TypeFlags.Any || !isTypeAssignableTo(getPermissiveInstantiation(checkType), getPermissiveInstantiation(inferredExtendsType)))) { + // Return union of trueType and falseType for 'any' since it matches anything. Furthermore, for a + // distributive conditional type applied to the constraint of a type variable, include trueType if + // there are possible values of the check type that are also possible values of the extends type. + // We use a reverse assignability check as it is less expensive than the comparable relationship + // and avoids false positives of a non-empty intersection check. + if (checkType.flags & TypeFlags.Any || forConstraint && !(inferredExtendsType.flags & TypeFlags.Never) && someType(getPermissiveInstantiation(inferredExtendsType), t => isTypeAssignableTo(t, getPermissiveInstantiation(checkType)))) { + (extraTypes || (extraTypes = [])).push(instantiateType(getTypeFromTypeNode(root.node.trueType), combinedMapper || mapper)); + } + // If falseType is an immediately nested conditional type that isn't distributive or has an + // identical checkType, switch to that type and loop. + const falseType = getTypeFromTypeNode(root.node.falseType); + if (falseType.flags & TypeFlags.Conditional) { + const newRoot = (falseType as ConditionalType).root; + if (newRoot.node.parent === root.node && (!newRoot.isDistributive || newRoot.checkType === root.checkType)) { + root = newRoot; + continue; + } + if (canTailRecurse(falseType, mapper)) { + continue; + } + } + result = instantiateType(falseType, mapper); + break; + } + // Return trueType for a definitely true extends check. We check instantiations of the two + // types with type parameters mapped to their restrictive form, i.e. a form of the type parameter + // that has no constraint. This ensures that, for example, the type + // type Foo = T extends { x: string } ? string : number + // doesn't immediately resolve to 'string' instead of being deferred. + if (inferredExtendsType.flags & TypeFlags.AnyOrUnknown || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(inferredExtendsType))) { + const trueType = getTypeFromTypeNode(root.node.trueType); + const trueMapper = combinedMapper || mapper; + if (canTailRecurse(trueType, trueMapper)) { + continue; + } + result = instantiateType(trueType, trueMapper); + break; + } + } + // Return a deferred type for a check that is neither definitely true nor definitely false + result = createType(TypeFlags.Conditional) as ConditionalType; + result.root = root; + result.checkType = instantiateType(root.checkType, mapper); + result.extendsType = instantiateType(root.extendsType, mapper); + result.mapper = mapper; + result.combinedMapper = combinedMapper; + result.aliasSymbol = aliasSymbol || root.aliasSymbol; + result.aliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(root.aliasTypeArguments, mapper!); // TODO: GH#18217 + break; + } + return extraTypes ? getUnionType(append(extraTypes, result)) : result; + // We tail-recurse for generic conditional types that (a) have not already been evaluated and cached, and + // (b) are non distributive, have a check type that is unaffected by instantiation, or have a non-union check + // type. Note that recursion is possible only through aliased conditional types, so we only increment the tail + // recursion counter for those. + function canTailRecurse(newType: Type, newMapper: TypeMapper | undefined) { + if (newType.flags & TypeFlags.Conditional && newMapper) { + const newRoot = (newType as ConditionalType).root; + if (newRoot.outerTypeParameters) { + const typeParamMapper = combineTypeMappers((newType as ConditionalType).mapper, newMapper); + const typeArguments = map(newRoot.outerTypeParameters, t => getMappedType(t, typeParamMapper)); + const newRootMapper = createTypeMapper(newRoot.outerTypeParameters, typeArguments); + const newCheckType = newRoot.isDistributive ? getMappedType(newRoot.checkType, newRootMapper) : undefined; + if (!newCheckType || newCheckType === newRoot.checkType || !(newCheckType.flags & (TypeFlags.Union | TypeFlags.Never))) { + root = newRoot; + mapper = newRootMapper; + aliasSymbol = undefined; + aliasTypeArguments = undefined; + if (newRoot.aliasSymbol) { + tailCount++; + } + return true; + } + } + } + return false; + } + } + + function getTrueTypeFromConditionalType(type: ConditionalType) { + return type.resolvedTrueType || (type.resolvedTrueType = instantiateType(getTypeFromTypeNode(type.root.node.trueType), type.mapper)); + } + + function getFalseTypeFromConditionalType(type: ConditionalType) { + return type.resolvedFalseType || (type.resolvedFalseType = instantiateType(getTypeFromTypeNode(type.root.node.falseType), type.mapper)); + } + + function getInferredTrueTypeFromConditionalType(type: ConditionalType) { + return type.resolvedInferredTrueType || (type.resolvedInferredTrueType = type.combinedMapper ? instantiateType(getTypeFromTypeNode(type.root.node.trueType), type.combinedMapper) : getTrueTypeFromConditionalType(type)); + } + + function getInferTypeParameters(node: ConditionalTypeNode): TypeParameter[] | undefined { + let result: TypeParameter[] | undefined; + if (node.locals) { + node.locals.forEach(symbol => { + if (symbol.flags & SymbolFlags.TypeParameter) { + result = append(result, getDeclaredTypeOfSymbol(symbol)); + } + }); + } + return result; + } + + function isDistributionDependent(root: ConditionalRoot) { + return root.isDistributive && ( + isTypeParameterPossiblyReferenced(root.checkType as TypeParameter, root.node.trueType) || + isTypeParameterPossiblyReferenced(root.checkType as TypeParameter, root.node.falseType) + ); + } + + function getTypeFromConditionalTypeNode(node: ConditionalTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const checkType = getTypeFromTypeNode(node.checkType); + const aliasSymbol = getAliasSymbolForTypeNode(node); + const aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); + const allOuterTypeParameters = getOuterTypeParameters(node, /*includeThisTypes*/ true); + const outerTypeParameters = aliasTypeArguments ? allOuterTypeParameters : filter(allOuterTypeParameters, tp => isTypeParameterPossiblyReferenced(tp, node)); + const root: ConditionalRoot = { + node, + checkType, + extendsType: getTypeFromTypeNode(node.extendsType), + isDistributive: !!(checkType.flags & TypeFlags.TypeParameter), + inferTypeParameters: getInferTypeParameters(node), + outerTypeParameters, + instantiations: undefined, + aliasSymbol, + aliasTypeArguments, + }; + links.resolvedType = getConditionalType(root, /*mapper*/ undefined, /*forConstraint*/ false); + if (outerTypeParameters) { + root.instantiations = new Map(); + root.instantiations.set(getTypeListId(outerTypeParameters), links.resolvedType); + } + } + return links.resolvedType; + } + + function getTypeFromInferTypeNode(node: InferTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node.typeParameter)); + } + return links.resolvedType; + } + + function getIdentifierChain(node: EntityName): Identifier[] { + if (isIdentifier(node)) { + return [node]; + } + else { + return append(getIdentifierChain(node.left), node.right); + } + } + + function getTypeFromImportTypeNode(node: ImportTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + if (!isLiteralImportTypeNode(node)) { + error(node.argument, Diagnostics.String_literal_expected); + links.resolvedSymbol = unknownSymbol; + return links.resolvedType = errorType; + } + const targetMeaning = node.isTypeOf ? SymbolFlags.Value : node.flags & NodeFlags.JSDoc ? SymbolFlags.Value | SymbolFlags.Type : SymbolFlags.Type; + // TODO: Future work: support unions/generics/whatever via a deferred import-type + const innerModuleSymbol = resolveExternalModuleName(node, node.argument.literal); + if (!innerModuleSymbol) { + links.resolvedSymbol = unknownSymbol; + return links.resolvedType = errorType; + } + const isExportEquals = !!innerModuleSymbol.exports?.get(InternalSymbolName.ExportEquals); + const moduleSymbol = resolveExternalModuleSymbol(innerModuleSymbol, /*dontResolveAlias*/ false); + if (!nodeIsMissing(node.qualifier)) { + const nameStack: Identifier[] = getIdentifierChain(node.qualifier!); + let currentNamespace = moduleSymbol; + let current: Identifier | undefined; + while (current = nameStack.shift()) { + const meaning = nameStack.length ? SymbolFlags.Namespace : targetMeaning; + // typeof a.b.c is normally resolved using `checkExpression` which in turn defers to `checkQualifiedName` + // That, in turn, ultimately uses `getPropertyOfType` on the type of the symbol, which differs slightly from + // the `exports` lookup process that only looks up namespace members which is used for most type references + const mergedResolvedSymbol = getMergedSymbol(resolveSymbol(currentNamespace)); + const symbolFromVariable = node.isTypeOf || isInJSFile(node) && isExportEquals + ? getPropertyOfType(getTypeOfSymbol(mergedResolvedSymbol), current.escapedText, /*skipObjectFunctionPropertyAugment*/ false, /*includeTypeOnlyMembers*/ true) + : undefined; + const symbolFromModule = node.isTypeOf ? undefined : getSymbol(getExportsOfSymbol(mergedResolvedSymbol), current.escapedText, meaning); + const next = symbolFromModule ?? symbolFromVariable; + if (!next) { + error(current, Diagnostics.Namespace_0_has_no_exported_member_1, getFullyQualifiedName(currentNamespace), declarationNameToString(current)); + return links.resolvedType = errorType; + } + getNodeLinks(current).resolvedSymbol = next; + getNodeLinks(current.parent).resolvedSymbol = next; + currentNamespace = next; + } + links.resolvedType = resolveImportSymbolType(node, links, currentNamespace, targetMeaning); + } + else { + if (moduleSymbol.flags & targetMeaning) { + links.resolvedType = resolveImportSymbolType(node, links, moduleSymbol, targetMeaning); + } + else { + const errorMessage = targetMeaning === SymbolFlags.Value + ? Diagnostics.Module_0_does_not_refer_to_a_value_but_is_used_as_a_value_here + : Diagnostics.Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here_Did_you_mean_typeof_import_0; + + error(node, errorMessage, node.argument.literal.text); + + links.resolvedSymbol = unknownSymbol; + links.resolvedType = errorType; + } + } + } + return links.resolvedType; + } + + function resolveImportSymbolType(node: ImportTypeNode, links: NodeLinks, symbol: Symbol, meaning: SymbolFlags) { + const resolvedSymbol = resolveSymbol(symbol); + links.resolvedSymbol = resolvedSymbol; + if (meaning === SymbolFlags.Value) { + return getInstantiationExpressionType(getTypeOfSymbol(symbol), node); // intentionally doesn't use resolved symbol so type is cached as expected on the alias + } + else { + return getTypeReferenceType(node, resolvedSymbol); // getTypeReferenceType doesn't handle aliases - it must get the resolved symbol + } + } + + function getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node: TypeLiteralNode | FunctionOrConstructorTypeNode | JSDocTypeLiteral | JSDocFunctionType | JSDocSignature): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + // Deferred resolution of members is handled by resolveObjectTypeMembers + const aliasSymbol = getAliasSymbolForTypeNode(node); + if (getMembersOfSymbol(node.symbol).size === 0 && !aliasSymbol) { + links.resolvedType = emptyTypeLiteralType; + } + else { + let type = createObjectType(ObjectFlags.Anonymous, node.symbol); + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); + if (isJSDocTypeLiteral(node) && node.isArrayType) { + type = createArrayType(type); + } + links.resolvedType = type; + } + } + return links.resolvedType; + } + + function getAliasSymbolForTypeNode(node: Node) { + let host = node.parent; + while (isParenthesizedTypeNode(host) || isJSDocTypeExpression(host) || isTypeOperatorNode(host) && host.operator === SyntaxKind.ReadonlyKeyword) { + host = host.parent; + } + return isTypeAlias(host) ? getSymbolOfDeclaration(host) : undefined; + } + + function getTypeArgumentsForAliasSymbol(symbol: Symbol | undefined) { + return symbol ? getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol) : undefined; + } + + function isNonGenericObjectType(type: Type) { + return !!(type.flags & TypeFlags.Object) && !isGenericMappedType(type); + } + + function isEmptyObjectTypeOrSpreadsIntoEmptyObject(type: Type) { + return isEmptyObjectType(type) || !!(type.flags & (TypeFlags.Null | TypeFlags.Undefined | TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)); + } + + function tryMergeUnionOfObjectTypeAndEmptyObject(type: Type, readonly: boolean): Type { + if (!(type.flags & TypeFlags.Union)) { + return type; + } + if (every((type as UnionType).types, isEmptyObjectTypeOrSpreadsIntoEmptyObject)) { + return find((type as UnionType).types, isEmptyObjectType) || emptyObjectType; + } + const firstType = find((type as UnionType).types, t => !isEmptyObjectTypeOrSpreadsIntoEmptyObject(t)); + if (!firstType) { + return type; + } + const secondType = find((type as UnionType).types, t => t !== firstType && !isEmptyObjectTypeOrSpreadsIntoEmptyObject(t)); + if (secondType) { + return type; + } + return getAnonymousPartialType(firstType); + + function getAnonymousPartialType(type: Type) { + // gets the type as if it had been spread, but where everything in the spread is made optional + const members = createSymbolTable(); + for (const prop of getPropertiesOfType(type)) { + if (getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) { + // do nothing, skip privates + } + else if (isSpreadableProperty(prop)) { + const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); + const flags = SymbolFlags.Property | SymbolFlags.Optional; + const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0)); + result.links.type = isSetonlyAccessor ? undefinedType : addOptionality(getTypeOfSymbol(prop), /*isProperty*/ true); + result.declarations = prop.declarations; + result.links.nameType = getSymbolLinks(prop).nameType; + result.links.syntheticOrigin = prop; + members.set(prop.escapedName, result); + } + } + const spread = createAnonymousType(type.symbol, members, emptyArray, emptyArray, getIndexInfosOfType(type)); + spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + return spread; + } + } + + /** + * Since the source of spread types are object literals, which are not binary, + * this function should be called in a left folding style, with left = previous result of getSpreadType + * and right = the new element to be spread. + */ + function getSpreadType(left: Type, right: Type, symbol: Symbol | undefined, objectFlags: ObjectFlags, readonly: boolean): Type { + if (left.flags & TypeFlags.Any || right.flags & TypeFlags.Any) { + return anyType; + } + if (left.flags & TypeFlags.Unknown || right.flags & TypeFlags.Unknown) { + return unknownType; + } + if (left.flags & TypeFlags.Never) { + return right; + } + if (right.flags & TypeFlags.Never) { + return left; + } + left = tryMergeUnionOfObjectTypeAndEmptyObject(left, readonly); + if (left.flags & TypeFlags.Union) { + return checkCrossProductUnion([left, right]) + ? mapType(left, t => getSpreadType(t, right, symbol, objectFlags, readonly)) + : errorType; + } + right = tryMergeUnionOfObjectTypeAndEmptyObject(right, readonly); + if (right.flags & TypeFlags.Union) { + return checkCrossProductUnion([left, right]) + ? mapType(right, t => getSpreadType(left, t, symbol, objectFlags, readonly)) + : errorType; + } + if (right.flags & (TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)) { + return left; + } + + if (isGenericObjectType(left) || isGenericObjectType(right)) { + if (isEmptyObjectType(left)) { + return right; + } + // When the left type is an intersection, we may need to merge the last constituent of the + // intersection with the right type. For example when the left type is 'T & { a: string }' + // and the right type is '{ b: string }' we produce 'T & { a: string, b: string }'. + if (left.flags & TypeFlags.Intersection) { + const types = (left as IntersectionType).types; + const lastLeft = types[types.length - 1]; + if (isNonGenericObjectType(lastLeft) && isNonGenericObjectType(right)) { + return getIntersectionType(concatenate(types.slice(0, types.length - 1), [getSpreadType(lastLeft, right, symbol, objectFlags, readonly)])); + } + } + return getIntersectionType([left, right]); + } + + const members = createSymbolTable(); + const skippedPrivateMembers = new Set<__String>(); + const indexInfos = left === emptyObjectType ? getIndexInfosOfType(right) : getUnionIndexInfos([left, right]); + + for (const rightProp of getPropertiesOfType(right)) { + if (getDeclarationModifierFlagsFromSymbol(rightProp) & (ModifierFlags.Private | ModifierFlags.Protected)) { + skippedPrivateMembers.add(rightProp.escapedName); + } + else if (isSpreadableProperty(rightProp)) { + members.set(rightProp.escapedName, getSpreadSymbol(rightProp, readonly)); + } + } + + for (const leftProp of getPropertiesOfType(left)) { + if (skippedPrivateMembers.has(leftProp.escapedName) || !isSpreadableProperty(leftProp)) { + continue; + } + if (members.has(leftProp.escapedName)) { + const rightProp = members.get(leftProp.escapedName)!; + const rightType = getTypeOfSymbol(rightProp); + if (rightProp.flags & SymbolFlags.Optional) { + const declarations = concatenate(leftProp.declarations, rightProp.declarations); + const flags = SymbolFlags.Property | (leftProp.flags & SymbolFlags.Optional); + const result = createSymbol(flags, leftProp.escapedName); + // Optimization: avoid calculating the union type if spreading into the exact same type. + // This is common, e.g. spreading one options bag into another where the bags have the + // same type, or have properties which overlap. If the unions are large, it may turn out + // to be expensive to perform subtype reduction. + const leftType = getTypeOfSymbol(leftProp); + const leftTypeWithoutUndefined = removeMissingOrUndefinedType(leftType); + const rightTypeWithoutUndefined = removeMissingOrUndefinedType(rightType); + result.links.type = leftTypeWithoutUndefined === rightTypeWithoutUndefined ? leftType : getUnionType([leftType, rightTypeWithoutUndefined], UnionReduction.Subtype); + result.links.leftSpread = leftProp; + result.links.rightSpread = rightProp; + result.declarations = declarations; + result.links.nameType = getSymbolLinks(leftProp).nameType; + members.set(leftProp.escapedName, result); + } + } + else { + members.set(leftProp.escapedName, getSpreadSymbol(leftProp, readonly)); + } + } + + const spread = createAnonymousType(symbol, members, emptyArray, emptyArray, sameMap(indexInfos, info => getIndexInfoWithReadonly(info, readonly))); + spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral | ObjectFlags.ContainsSpread | objectFlags; + return spread; + } + + /** We approximate own properties as non-methods plus methods that are inside the object literal */ + function isSpreadableProperty(prop: Symbol): boolean { + return !some(prop.declarations, isPrivateIdentifierClassElementDeclaration) && + (!(prop.flags & (SymbolFlags.Method | SymbolFlags.GetAccessor | SymbolFlags.SetAccessor)) || + !prop.declarations?.some(decl => isClassLike(decl.parent))); + } + + function getSpreadSymbol(prop: Symbol, readonly: boolean) { + const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); + if (!isSetonlyAccessor && readonly === isReadonlySymbol(prop)) { + return prop; + } + const flags = SymbolFlags.Property | (prop.flags & SymbolFlags.Optional); + const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0)); + result.links.type = isSetonlyAccessor ? undefinedType : getTypeOfSymbol(prop); + result.declarations = prop.declarations; + result.links.nameType = getSymbolLinks(prop).nameType; + result.links.syntheticOrigin = prop; + return result; + } + + function getIndexInfoWithReadonly(info: IndexInfo, readonly: boolean) { + return info.isReadonly !== readonly ? createIndexInfo(info.keyType, info.type, readonly, info.declaration) : info; + } + + function createLiteralType(flags: TypeFlags, value: string | number | PseudoBigInt, symbol?: Symbol, regularType?: LiteralType) { + const type = createTypeWithSymbol(flags, symbol!) as LiteralType; + type.value = value; + type.regularType = regularType || type; + return type; + } + + function getFreshTypeOfLiteralType(type: Type): Type { + if (type.flags & TypeFlags.Freshable) { + if (!(type as FreshableType).freshType) { + const freshType = createLiteralType(type.flags, (type as LiteralType).value, (type as LiteralType).symbol, type as LiteralType); + freshType.freshType = freshType; + (type as FreshableType).freshType = freshType; + } + return (type as FreshableType).freshType; + } + return type; + } + + function getRegularTypeOfLiteralType(type: Type): Type { + return type.flags & TypeFlags.Freshable ? (type as FreshableType).regularType : + type.flags & TypeFlags.Union ? ((type as UnionType).regularType || ((type as UnionType).regularType = mapType(type, getRegularTypeOfLiteralType) as UnionType)) : + type; + } + + function isFreshLiteralType(type: Type) { + return !!(type.flags & TypeFlags.Freshable) && (type as LiteralType).freshType === type; + } + + function getStringLiteralType(value: string): StringLiteralType { + let type; + return stringLiteralTypes.get(value) || + (stringLiteralTypes.set(value, type = createLiteralType(TypeFlags.StringLiteral, value) as StringLiteralType), type); + } + + function getNumberLiteralType(value: number): NumberLiteralType { + let type; + return numberLiteralTypes.get(value) || + (numberLiteralTypes.set(value, type = createLiteralType(TypeFlags.NumberLiteral, value) as NumberLiteralType), type); + } + + function getBigIntLiteralType(value: PseudoBigInt): BigIntLiteralType { + let type; + const key = pseudoBigIntToString(value); + return bigIntLiteralTypes.get(key) || + (bigIntLiteralTypes.set(key, type = createLiteralType(TypeFlags.BigIntLiteral, value) as BigIntLiteralType), type); + } + + function getEnumLiteralType(value: string | number, enumId: number, symbol: Symbol): LiteralType { + let type; + const key = `${enumId}${typeof value === "string" ? "@" : "#"}${value}`; + const flags = TypeFlags.EnumLiteral | (typeof value === "string" ? TypeFlags.StringLiteral : TypeFlags.NumberLiteral); + return enumLiteralTypes.get(key) || + (enumLiteralTypes.set(key, type = createLiteralType(flags, value, symbol)), type); + } + + function getTypeFromLiteralTypeNode(node: LiteralTypeNode): Type { + if (node.literal.kind === SyntaxKind.NullKeyword) { + return nullType; + } + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getRegularTypeOfLiteralType(checkExpression(node.literal)); + } + return links.resolvedType; + } + + function createUniqueESSymbolType(symbol: Symbol) { + const type = createTypeWithSymbol(TypeFlags.UniqueESSymbol, symbol) as UniqueESSymbolType; + type.escapedName = `__@${type.symbol.escapedName}@${getSymbolId(type.symbol)}` as __String; + return type; + } + + function getESSymbolLikeTypeForNode(node: Node) { + if (isInJSFile(node) && isJSDocTypeExpression(node)) { + const host = getJSDocHost(node); + if (host) { + node = getSingleVariableOfVariableStatement(host) || host; + } + } + if (isValidESSymbolDeclaration(node)) { + const symbol = isCommonJsExportPropertyAssignment(node) ? getSymbolOfNode((node as BinaryExpression).left) : getSymbolOfNode(node); + if (symbol) { + const links = getSymbolLinks(symbol); + return links.uniqueESSymbolType || (links.uniqueESSymbolType = createUniqueESSymbolType(symbol)); + } + } + return esSymbolType; + } + + function getThisType(node: Node): Type { + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + const parent = container && container.parent; + if (parent && (isClassLike(parent) || parent.kind === SyntaxKind.InterfaceDeclaration)) { + if ( + !isStatic(container) && + (!isConstructorDeclaration(container) || isNodeDescendantOf(node, container.body)) + ) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(parent as ClassLikeDeclaration | InterfaceDeclaration)).thisType!; + } + } + + // inside x.prototype = { ... } + if (parent && isObjectLiteralExpression(parent) && isBinaryExpression(parent.parent) && getAssignmentDeclarationKind(parent.parent) === AssignmentDeclarationKind.Prototype) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfNode(parent.parent.left)!.parent!).thisType!; + } + // /** @return {this} */ + // x.prototype.m = function() { ... } + const host = node.flags & NodeFlags.JSDoc ? getHostSignatureFromJSDoc(node) : undefined; + if (host && isFunctionExpression(host) && isBinaryExpression(host.parent) && getAssignmentDeclarationKind(host.parent) === AssignmentDeclarationKind.PrototypeProperty) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfNode(host.parent.left)!.parent!).thisType!; + } + // inside constructor function C() { ... } + if (isJSConstructor(container) && isNodeDescendantOf(node, container.body)) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(container)).thisType!; + } + error(node, Diagnostics.A_this_type_is_available_only_in_a_non_static_member_of_a_class_or_interface); + return errorType; + } + + function getTypeFromThisTypeNode(node: ThisExpression | ThisTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getThisType(node); + } + return links.resolvedType; + } + + function getTypeFromRestTypeNode(node: RestTypeNode | NamedTupleMember) { + return getTypeFromTypeNode(getArrayElementTypeNode(node.type) || node.type); + } + + function getArrayElementTypeNode(node: TypeNode): TypeNode | undefined { + switch (node.kind) { + case SyntaxKind.ParenthesizedType: + return getArrayElementTypeNode((node as ParenthesizedTypeNode).type); + case SyntaxKind.TupleType: + if ((node as TupleTypeNode).elements.length === 1) { + node = (node as TupleTypeNode).elements[0]; + if (node.kind === SyntaxKind.RestType || node.kind === SyntaxKind.NamedTupleMember && (node as NamedTupleMember).dotDotDotToken) { + return getArrayElementTypeNode((node as RestTypeNode | NamedTupleMember).type); + } + } + break; + case SyntaxKind.ArrayType: + return (node as ArrayTypeNode).elementType; + } + return undefined; + } + + function getTypeFromNamedTupleTypeNode(node: NamedTupleMember): Type { + const links = getNodeLinks(node); + return links.resolvedType || (links.resolvedType = node.dotDotDotToken ? getTypeFromRestTypeNode(node) : + addOptionality(getTypeFromTypeNode(node.type), /*isProperty*/ true, !!node.questionToken)); + } + + function getTypeFromTypeNode(node: TypeNode): Type { + return getConditionalFlowTypeOfType(getTypeFromTypeNodeWorker(node), node); + } + + function getTypeFromTypeNodeWorker(node: TypeNode): Type { + switch (node.kind) { + case SyntaxKind.AnyKeyword: + case SyntaxKind.JSDocAllType: + case SyntaxKind.JSDocUnknownType: + return anyType; + case SyntaxKind.UnknownKeyword: + return unknownType; + case SyntaxKind.StringKeyword: + return stringType; + case SyntaxKind.NumberKeyword: + return numberType; + case SyntaxKind.BigIntKeyword: + return bigintType; + case SyntaxKind.BooleanKeyword: + return booleanType; + case SyntaxKind.SymbolKeyword: + return esSymbolType; + case SyntaxKind.VoidKeyword: + return voidType; + case SyntaxKind.UndefinedKeyword: + return undefinedType; + case SyntaxKind.NullKeyword as TypeNodeSyntaxKind: + // TODO(rbuckton): `NullKeyword` is no longer a `TypeNode`, but we defensively allow it here because of incorrect casts in the Language Service. + return nullType; + case SyntaxKind.NeverKeyword: + return neverType; + case SyntaxKind.ObjectKeyword: + return node.flags & NodeFlags.JavaScriptFile && !noImplicitAny ? anyType : nonPrimitiveType; + case SyntaxKind.IntrinsicKeyword: + return intrinsicMarkerType; + case SyntaxKind.ThisType: + case SyntaxKind.ThisKeyword as TypeNodeSyntaxKind: + // TODO(rbuckton): `ThisKeyword` is no longer a `TypeNode`, but we defensively allow it here because of incorrect casts in the Language Service and because of `isPartOfTypeNode`. + return getTypeFromThisTypeNode(node as ThisExpression | ThisTypeNode); + case SyntaxKind.LiteralType: + return getTypeFromLiteralTypeNode(node as LiteralTypeNode); + case SyntaxKind.TypeReference: + return getTypeFromTypeReference(node as TypeReferenceNode); + case SyntaxKind.TypePredicate: + return (node as TypePredicateNode).assertsModifier ? voidType : booleanType; + case SyntaxKind.ExpressionWithTypeArguments: + return getTypeFromTypeReference(node as ExpressionWithTypeArguments); + case SyntaxKind.TypeQuery: + return getTypeFromTypeQueryNode(node as TypeQueryNode); + case SyntaxKind.ArrayType: + case SyntaxKind.TupleType: + return getTypeFromArrayOrTupleTypeNode(node as ArrayTypeNode | TupleTypeNode); + case SyntaxKind.OptionalType: + return getTypeFromOptionalTypeNode(node as OptionalTypeNode); + case SyntaxKind.UnionType: + return getTypeFromUnionTypeNode(node as UnionTypeNode); + case SyntaxKind.IntersectionType: + return getTypeFromIntersectionTypeNode(node as IntersectionTypeNode); + case SyntaxKind.JSDocNullableType: + return getTypeFromJSDocNullableTypeNode(node as JSDocNullableType); + case SyntaxKind.JSDocOptionalType: + return addOptionality(getTypeFromTypeNode((node as JSDocOptionalType).type)); + case SyntaxKind.NamedTupleMember: + return getTypeFromNamedTupleTypeNode(node as NamedTupleMember); + case SyntaxKind.ParenthesizedType: + case SyntaxKind.JSDocNonNullableType: + case SyntaxKind.JSDocTypeExpression: + return getTypeFromTypeNode((node as ParenthesizedTypeNode | JSDocTypeReferencingNode | JSDocTypeExpression | NamedTupleMember).type); + case SyntaxKind.RestType: + return getTypeFromRestTypeNode(node as RestTypeNode); + case SyntaxKind.JSDocVariadicType: + return getTypeFromJSDocVariadicType(node as JSDocVariadicType); + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.TypeLiteral: + case SyntaxKind.JSDocTypeLiteral: + case SyntaxKind.JSDocFunctionType: + case SyntaxKind.JSDocSignature: + return getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node as TypeLiteralNode | FunctionOrConstructorTypeNode | JSDocTypeLiteral | JSDocFunctionType | JSDocSignature); + case SyntaxKind.TypeOperator: + return getTypeFromTypeOperatorNode(node as TypeOperatorNode); + case SyntaxKind.IndexedAccessType: + return getTypeFromIndexedAccessTypeNode(node as IndexedAccessTypeNode); + case SyntaxKind.MappedType: + return getTypeFromMappedTypeNode(node as MappedTypeNode); + case SyntaxKind.ConditionalType: + return getTypeFromConditionalTypeNode(node as ConditionalTypeNode); + case SyntaxKind.InferType: + return getTypeFromInferTypeNode(node as InferTypeNode); + case SyntaxKind.TemplateLiteralType: + return getTypeFromTemplateTypeNode(node as TemplateLiteralTypeNode); + case SyntaxKind.ImportType: + return getTypeFromImportTypeNode(node as ImportTypeNode); + // This function assumes that an identifier, qualified name, or property access expression is a type expression + // Callers should first ensure this by calling `isPartOfTypeNode` + // TODO(rbuckton): These aren't valid TypeNodes, but we treat them as such because of `isPartOfTypeNode`, which returns `true` for things that aren't `TypeNode`s. + case SyntaxKind.Identifier as TypeNodeSyntaxKind: + case SyntaxKind.QualifiedName as TypeNodeSyntaxKind: + case SyntaxKind.PropertyAccessExpression as TypeNodeSyntaxKind: + const symbol = getSymbolAtLocation(node); + return symbol ? getDeclaredTypeOfSymbol(symbol) : errorType; + default: + return errorType; + } + } + + function instantiateList(items: readonly T[], mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[]; + function instantiateList(items: readonly T[] | undefined, mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[] | undefined; + function instantiateList(items: readonly T[] | undefined, mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[] | undefined { + if (items && items.length) { + for (let i = 0; i < items.length; i++) { + const item = items[i]; + const mapped = instantiator(item, mapper); + if (item !== mapped) { + const result = i === 0 ? [] : items.slice(0, i); + result.push(mapped); + for (i++; i < items.length; i++) { + result.push(instantiator(items[i], mapper)); + } + return result; + } + } + } + return items; + } + + function instantiateTypes(types: readonly Type[], mapper: TypeMapper): readonly Type[]; + function instantiateTypes(types: readonly Type[] | undefined, mapper: TypeMapper): readonly Type[] | undefined; + function instantiateTypes(types: readonly Type[] | undefined, mapper: TypeMapper): readonly Type[] | undefined { + return instantiateList(types, mapper, instantiateType); + } + + function instantiateSignatures(signatures: readonly Signature[], mapper: TypeMapper): readonly Signature[] { + return instantiateList(signatures, mapper, instantiateSignature); + } + + function instantiateIndexInfos(indexInfos: readonly IndexInfo[], mapper: TypeMapper): readonly IndexInfo[] { + return instantiateList(indexInfos, mapper, instantiateIndexInfo); + } + + function createTypeMapper(sources: readonly TypeParameter[], targets: readonly Type[] | undefined): TypeMapper { + return sources.length === 1 ? makeUnaryTypeMapper(sources[0], targets ? targets[0] : anyType) : makeArrayTypeMapper(sources, targets); + } + + function getMappedType(type: Type, mapper: TypeMapper): Type { + switch (mapper.kind) { + case TypeMapKind.Simple: + return type === mapper.source ? mapper.target : type; + case TypeMapKind.Array: { + const sources = mapper.sources; + const targets = mapper.targets; + for (let i = 0; i < sources.length; i++) { + if (type === sources[i]) { + return targets ? targets[i] : anyType; + } + } + return type; + } + case TypeMapKind.Deferred: { + const sources = mapper.sources; + const targets = mapper.targets; + for (let i = 0; i < sources.length; i++) { + if (type === sources[i]) { + return targets[i](); + } + } + return type; + } + case TypeMapKind.Function: + return mapper.func(type); + case TypeMapKind.Composite: + case TypeMapKind.Merged: + const t1 = getMappedType(type, mapper.mapper1); + return t1 !== type && mapper.kind === TypeMapKind.Composite ? instantiateType(t1, mapper.mapper2) : getMappedType(t1, mapper.mapper2); + } + } + + function makeUnaryTypeMapper(source: Type, target: Type): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Simple, source, target }); + } + + function makeArrayTypeMapper(sources: readonly TypeParameter[], targets: readonly Type[] | undefined): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Array, sources, targets }); + } + + function makeFunctionTypeMapper(func: (t: Type) => Type, debugInfo: () => string): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Function, func, debugInfo: Debug.isDebugging ? debugInfo : undefined }); + } + + function makeDeferredTypeMapper(sources: readonly TypeParameter[], targets: (() => Type)[]) { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Deferred, sources, targets }); + } + + function makeCompositeTypeMapper(kind: TypeMapKind.Composite | TypeMapKind.Merged, mapper1: TypeMapper, mapper2: TypeMapper): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind, mapper1, mapper2 }); + } + + function createTypeEraser(sources: readonly TypeParameter[]): TypeMapper { + return createTypeMapper(sources, /*targets*/ undefined); + } + + /** + * Maps forward-references to later types parameters to the empty object type. + * This is used during inference when instantiating type parameter defaults. + */ + function createBackreferenceMapper(context: InferenceContext, index: number): TypeMapper { + const forwardInferences = context.inferences.slice(index); + return createTypeMapper(map(forwardInferences, i => i.typeParameter), map(forwardInferences, () => unknownType)); + } + + function combineTypeMappers(mapper1: TypeMapper | undefined, mapper2: TypeMapper): TypeMapper { + return mapper1 ? makeCompositeTypeMapper(TypeMapKind.Composite, mapper1, mapper2) : mapper2; + } + + function mergeTypeMappers(mapper1: TypeMapper | undefined, mapper2: TypeMapper): TypeMapper { + return mapper1 ? makeCompositeTypeMapper(TypeMapKind.Merged, mapper1, mapper2) : mapper2; + } + + function prependTypeMapping(source: Type, target: Type, mapper: TypeMapper | undefined) { + return !mapper ? makeUnaryTypeMapper(source, target) : makeCompositeTypeMapper(TypeMapKind.Merged, makeUnaryTypeMapper(source, target), mapper); + } + + function appendTypeMapping(mapper: TypeMapper | undefined, source: Type, target: Type) { + return !mapper ? makeUnaryTypeMapper(source, target) : makeCompositeTypeMapper(TypeMapKind.Merged, mapper, makeUnaryTypeMapper(source, target)); + } + + function getRestrictiveTypeParameter(tp: TypeParameter) { + return !tp.constraint && !getConstraintDeclaration(tp) || tp.constraint === noConstraintType ? tp : tp.restrictiveInstantiation || ( + tp.restrictiveInstantiation = createTypeParameter(tp.symbol), (tp.restrictiveInstantiation as TypeParameter).constraint = noConstraintType, tp.restrictiveInstantiation + ); + } + + function cloneTypeParameter(typeParameter: TypeParameter): TypeParameter { + const result = createTypeParameter(typeParameter.symbol); + result.target = typeParameter; + return result; + } + + function instantiateTypePredicate(predicate: TypePredicate, mapper: TypeMapper): TypePredicate { + return createTypePredicate(predicate.kind, predicate.parameterName, predicate.parameterIndex, instantiateType(predicate.type, mapper)); + } + + function instantiateSignature(signature: Signature, mapper: TypeMapper, eraseTypeParameters?: boolean): Signature { + let freshTypeParameters: TypeParameter[] | undefined; + if (signature.typeParameters && !eraseTypeParameters) { + // First create a fresh set of type parameters, then include a mapping from the old to the + // new type parameters in the mapper function. Finally store this mapper in the new type + // parameters such that we can use it when instantiating constraints. + freshTypeParameters = map(signature.typeParameters, cloneTypeParameter); + mapper = combineTypeMappers(createTypeMapper(signature.typeParameters, freshTypeParameters), mapper); + for (const tp of freshTypeParameters) { + tp.mapper = mapper; + } + } + // Don't compute resolvedReturnType and resolvedTypePredicate now, + // because using `mapper` now could trigger inferences to become fixed. (See `createInferenceContext`.) + // See GH#17600. + const result = createSignature(signature.declaration, freshTypeParameters, signature.thisParameter && instantiateSymbol(signature.thisParameter, mapper), instantiateList(signature.parameters, mapper, instantiateSymbol), /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, signature.minArgumentCount, signature.flags & SignatureFlags.PropagatingFlags); + result.target = signature; + result.mapper = mapper; + return result; + } + + function instantiateSymbol(symbol: Symbol, mapper: TypeMapper): Symbol { + const links = getSymbolLinks(symbol); + // If the type of the symbol is already resolved, and if that type could not possibly + // be affected by instantiation, simply return the symbol itself. + if (links.type && !couldContainTypeVariables(links.type)) { + if (!(symbol.flags & SymbolFlags.SetAccessor)) { + return symbol; + } + // If we're a setter, check writeType. + if (links.writeType && !couldContainTypeVariables(links.writeType)) { + return symbol; + } + } + if (getCheckFlags(symbol) & CheckFlags.Instantiated) { + // If symbol being instantiated is itself a instantiation, fetch the original target and combine the + // type mappers. This ensures that original type identities are properly preserved and that aliases + // always reference a non-aliases. + symbol = links.target!; + mapper = combineTypeMappers(links.mapper, mapper); + } + // Keep the flags from the symbol we're instantiating. Mark that is instantiated, and + // also transient so that we can just store data on it directly. + const result = createSymbol(symbol.flags, symbol.escapedName, CheckFlags.Instantiated | getCheckFlags(symbol) & (CheckFlags.Readonly | CheckFlags.Late | CheckFlags.OptionalParameter | CheckFlags.RestParameter)); + result.declarations = symbol.declarations; + result.parent = symbol.parent; + result.links.target = symbol; + result.links.mapper = mapper; + if (symbol.valueDeclaration) { + result.valueDeclaration = symbol.valueDeclaration; + } + if (links.nameType) { + result.links.nameType = links.nameType; + } + return result; + } + + function getObjectTypeInstantiation(type: AnonymousType | DeferredTypeReference, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]) { + const declaration = type.objectFlags & ObjectFlags.Reference ? (type as TypeReference).node! : + type.objectFlags & ObjectFlags.InstantiationExpressionType ? (type as InstantiationExpressionType).node : + type.symbol.declarations![0]; + const links = getNodeLinks(declaration); + const target = type.objectFlags & ObjectFlags.Reference ? links.resolvedType! as DeferredTypeReference : + type.objectFlags & ObjectFlags.Instantiated ? type.target! : type; + let typeParameters = type.objectFlags & ObjectFlags.SingleSignatureType ? (type as SingleSignatureType).outerTypeParameters : links.outerTypeParameters; + if (!typeParameters) { + // The first time an anonymous type is instantiated we compute and store a list of the type + // parameters that are in scope (and therefore potentially referenced). For type literals that + // aren't the right hand side of a generic type alias declaration we optimize by reducing the + // set of type parameters to those that are possibly referenced in the literal. + let outerTypeParameters = getOuterTypeParameters(declaration, /*includeThisTypes*/ true); + if (isJSConstructor(declaration)) { + const templateTagParameters = getTypeParametersFromDeclaration(declaration as DeclarationWithTypeParameters); + outerTypeParameters = addRange(outerTypeParameters, templateTagParameters); + } + typeParameters = outerTypeParameters || emptyArray; + const allDeclarations = type.objectFlags & (ObjectFlags.Reference | ObjectFlags.InstantiationExpressionType) ? [declaration] : type.symbol.declarations!; + typeParameters = (target.objectFlags & (ObjectFlags.Reference | ObjectFlags.InstantiationExpressionType) || target.symbol.flags & SymbolFlags.Method || target.symbol.flags & SymbolFlags.TypeLiteral) && !target.aliasTypeArguments ? + filter(typeParameters, tp => some(allDeclarations, d => isTypeParameterPossiblyReferenced(tp, d))) : + typeParameters; + links.outerTypeParameters = typeParameters; + } + if (typeParameters.length) { + // We are instantiating an anonymous type that has one or more type parameters in scope. Apply the + // mapper to the type parameters to produce the effective list of type arguments, and compute the + // instantiation cache key from the type IDs of the type arguments. + const combinedMapper = combineTypeMappers(type.mapper, mapper); + const typeArguments = map(typeParameters, t => getMappedType(t, combinedMapper)); + const newAliasSymbol = aliasSymbol || type.aliasSymbol; + const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + const id = (type.objectFlags & ObjectFlags.SingleSignatureType ? "S" : "") + getTypeListId(typeArguments) + getAliasId(newAliasSymbol, newAliasTypeArguments); + if (!target.instantiations) { + target.instantiations = new Map(); + target.instantiations.set(getTypeListId(typeParameters) + getAliasId(target.aliasSymbol, target.aliasTypeArguments), target); + } + let result = target.instantiations.get(id); + if (!result) { + if (type.objectFlags & ObjectFlags.SingleSignatureType) { + result = instantiateAnonymousType(type, mapper); + target.instantiations.set(id, result); + return result; + } + const newMapper = createTypeMapper(typeParameters, typeArguments); + result = target.objectFlags & ObjectFlags.Reference ? createDeferredTypeReference((type as DeferredTypeReference).target, (type as DeferredTypeReference).node, newMapper, newAliasSymbol, newAliasTypeArguments) : + target.objectFlags & ObjectFlags.Mapped ? instantiateMappedType(target as MappedType, newMapper, newAliasSymbol, newAliasTypeArguments) : + instantiateAnonymousType(target, newMapper, newAliasSymbol, newAliasTypeArguments); + target.instantiations.set(id, result); // Set cached result early in case we recursively invoke instantiation while eagerly computing type variable visibility below + const resultObjectFlags = getObjectFlags(result); + if (result.flags & TypeFlags.ObjectFlagsType && !(resultObjectFlags & ObjectFlags.CouldContainTypeVariablesComputed)) { + const resultCouldContainTypeVariables = some(typeArguments, couldContainTypeVariables); // one of the input type arguments might be or contain the result + if (!(getObjectFlags(result) & ObjectFlags.CouldContainTypeVariablesComputed)) { + // if `result` is one of the object types we tried to make (it may not be, due to how `instantiateMappedType` works), we can carry forward the type variable containment check from the input type arguments + if (resultObjectFlags & (ObjectFlags.Mapped | ObjectFlags.Anonymous | ObjectFlags.Reference)) { + (result as ObjectFlagsType).objectFlags |= ObjectFlags.CouldContainTypeVariablesComputed | (resultCouldContainTypeVariables ? ObjectFlags.CouldContainTypeVariables : 0); + } + // If none of the type arguments for the outer type parameters contain type variables, it follows + // that the instantiated type doesn't reference type variables. + // Intrinsics have `CouldContainTypeVariablesComputed` pre-set, so this should only cover unions and intersections resulting from `instantiateMappedType` + else { + (result as ObjectFlagsType).objectFlags |= !resultCouldContainTypeVariables ? ObjectFlags.CouldContainTypeVariablesComputed : 0; + } + } + } + } + return result; + } + return type; + } + + function maybeTypeParameterReference(node: Node) { + return !(node.parent.kind === SyntaxKind.TypeReference && (node.parent as TypeReferenceNode).typeArguments && node === (node.parent as TypeReferenceNode).typeName || + node.parent.kind === SyntaxKind.ImportType && (node.parent as ImportTypeNode).typeArguments && node === (node.parent as ImportTypeNode).qualifier); + } + + function isTypeParameterPossiblyReferenced(tp: TypeParameter, node: Node) { + // If the type parameter doesn't have exactly one declaration, if there are intervening statement blocks + // between the node and the type parameter declaration, if the node contains actual references to the + // type parameter, or if the node contains type queries that we can't prove couldn't contain references to the type parameter, + // we consider the type parameter possibly referenced. + if (tp.symbol && tp.symbol.declarations && tp.symbol.declarations.length === 1) { + const container = tp.symbol.declarations[0].parent; + for (let n = node; n !== container; n = n.parent) { + if (!n || n.kind === SyntaxKind.Block || n.kind === SyntaxKind.ConditionalType && forEachChild((n as ConditionalTypeNode).extendsType, containsReference)) { + return true; + } + } + return containsReference(node); + } + return true; + function containsReference(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.ThisType: + return !!tp.isThisType; + case SyntaxKind.Identifier: + return !tp.isThisType && isPartOfTypeNode(node) && maybeTypeParameterReference(node) && + getTypeFromTypeNodeWorker(node as TypeNode) === tp; // use worker because we're looking for === equality + case SyntaxKind.TypeQuery: + const entityName = (node as TypeQueryNode).exprName; + const firstIdentifier = getFirstIdentifier(entityName); + if (!isThisIdentifier(firstIdentifier)) { // Don't attempt to analyze typeof this.xxx + const firstIdentifierSymbol = getResolvedSymbol(firstIdentifier); + const tpDeclaration = tp.symbol.declarations![0]; // There is exactly one declaration, otherwise `containsReference` is not called + const tpScope = tpDeclaration.kind === SyntaxKind.TypeParameter ? tpDeclaration.parent : // Type parameter is a regular type parameter, e.g. foo + tp.isThisType ? tpDeclaration : // Type parameter is the this type, and its declaration is the class declaration. + undefined; // Type parameter's declaration was unrecognized, e.g. comes from JSDoc annotation. + if (firstIdentifierSymbol.declarations && tpScope) { + return some(firstIdentifierSymbol.declarations, idDecl => isNodeDescendantOf(idDecl, tpScope)) || + some((node as TypeQueryNode).typeArguments, containsReference); + } + } + return true; + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + return !(node as FunctionLikeDeclaration).type && !!(node as FunctionLikeDeclaration).body || + some((node as FunctionLikeDeclaration).typeParameters, containsReference) || + some((node as FunctionLikeDeclaration).parameters, containsReference) || + !!(node as FunctionLikeDeclaration).type && containsReference((node as FunctionLikeDeclaration).type!); + } + return !!forEachChild(node, containsReference); + } + } + + function getHomomorphicTypeVariable(type: MappedType) { + const constraintType = getConstraintTypeFromMappedType(type); + if (constraintType.flags & TypeFlags.Index) { + const typeVariable = getActualTypeVariable((constraintType as IndexType).type); + if (typeVariable.flags & TypeFlags.TypeParameter) { + return typeVariable as TypeParameter; + } + } + return undefined; + } + + function instantiateMappedType(type: MappedType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + // For a homomorphic mapped type { [P in keyof T]: X }, where T is some type variable, the mapping + // operation depends on T as follows: + // * If T is a primitive type no mapping is performed and the result is simply T. + // * If T is a union type we distribute the mapped type over the union. + // * If T is an array we map to an array where the element type has been transformed. + // * If T is a tuple we map to a tuple where the element types have been transformed. + // * If T is an intersection of array or tuple types we map to an intersection of transformed array or tuple types. + // * Otherwise we map to an object type where the type of each property has been transformed. + // For example, when T is instantiated to a union type A | B, we produce { [P in keyof A]: X } | + // { [P in keyof B]: X }, and when when T is instantiated to a union type A | undefined, we produce + // { [P in keyof A]: X } | undefined. + const typeVariable = getHomomorphicTypeVariable(type); + if (typeVariable) { + const mappedTypeVariable = instantiateType(typeVariable, mapper); + if (typeVariable !== mappedTypeVariable) { + return mapTypeWithAlias(getReducedType(mappedTypeVariable), instantiateConstituent, aliasSymbol, aliasTypeArguments); + } + } + // If the constraint type of the instantiation is the wildcard type, return the wildcard type. + return instantiateType(getConstraintTypeFromMappedType(type), mapper) === wildcardType ? wildcardType : instantiateAnonymousType(type, mapper, aliasSymbol, aliasTypeArguments); + + function instantiateConstituent(t: Type): Type { + if (t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.InstantiableNonPrimitive | TypeFlags.Object | TypeFlags.Intersection) && t !== wildcardType && !isErrorType(t)) { + if (!type.declaration.nameType) { + let constraint; + if ( + isArrayType(t) || t.flags & TypeFlags.Any && findResolutionCycleStartIndex(typeVariable!, TypeSystemPropertyName.ImmediateBaseConstraint) < 0 && + (constraint = getConstraintOfTypeParameter(typeVariable!)) && everyType(constraint, isArrayOrTupleType) + ) { + return instantiateMappedArrayType(t, type, prependTypeMapping(typeVariable!, t, mapper)); + } + if (isTupleType(t)) { + return instantiateMappedTupleType(t, type, typeVariable!, mapper); + } + if (isArrayOrTupleOrIntersection(t)) { + return getIntersectionType(map((t as IntersectionType).types, instantiateConstituent)); + } + } + return instantiateAnonymousType(type, prependTypeMapping(typeVariable!, t, mapper)); + } + return t; + } + } + + function getModifiedReadonlyState(state: boolean, modifiers: MappedTypeModifiers) { + return modifiers & MappedTypeModifiers.IncludeReadonly ? true : modifiers & MappedTypeModifiers.ExcludeReadonly ? false : state; + } + + function instantiateMappedTupleType(tupleType: TupleTypeReference, mappedType: MappedType, typeVariable: TypeVariable, mapper: TypeMapper) { + // We apply the mapped type's template type to each of the fixed part elements. For variadic elements, we + // apply the mapped type itself to the variadic element type. For other elements in the variable part of the + // tuple, we surround the element type with an array type and apply the mapped type to that. This ensures + // that we get sequential property key types for the fixed part of the tuple, and property key type number + // for the remaining elements. For example + // + // type Keys = { [K in keyof T]: K }; + // type Foo = Keys<[string, string, ...T, string]>; // ["0", "1", ...Keys, number] + // + const elementFlags = tupleType.target.elementFlags; + const fixedLength = tupleType.target.fixedLength; + const fixedMapper = fixedLength ? prependTypeMapping(typeVariable, tupleType, mapper) : mapper; + const newElementTypes = map(getElementTypes(tupleType), (type, i) => { + const flags = elementFlags[i]; + return i < fixedLength ? instantiateMappedTypeTemplate(mappedType, getStringLiteralType("" + i), !!(flags & ElementFlags.Optional), fixedMapper) : + flags & ElementFlags.Variadic ? instantiateType(mappedType, prependTypeMapping(typeVariable, type, mapper)) : + getElementTypeOfArrayType(instantiateType(mappedType, prependTypeMapping(typeVariable, createArrayType(type), mapper))) ?? unknownType; + }); + const modifiers = getMappedTypeModifiers(mappedType); + const newElementFlags = modifiers & MappedTypeModifiers.IncludeOptional ? map(elementFlags, f => f & ElementFlags.Required ? ElementFlags.Optional : f) : + modifiers & MappedTypeModifiers.ExcludeOptional ? map(elementFlags, f => f & ElementFlags.Optional ? ElementFlags.Required : f) : + elementFlags; + const newReadonly = getModifiedReadonlyState(tupleType.target.readonly, getMappedTypeModifiers(mappedType)); + return contains(newElementTypes, errorType) ? errorType : + createTupleType(newElementTypes, newElementFlags, newReadonly, tupleType.target.labeledElementDeclarations); + } + + function instantiateMappedArrayType(arrayType: Type, mappedType: MappedType, mapper: TypeMapper) { + const elementType = instantiateMappedTypeTemplate(mappedType, numberType, /*isOptional*/ true, mapper); + return isErrorType(elementType) ? errorType : + createArrayType(elementType, getModifiedReadonlyState(isReadonlyArrayType(arrayType), getMappedTypeModifiers(mappedType))); + } + + function instantiateMappedTypeTemplate(type: MappedType, key: Type, isOptional: boolean, mapper: TypeMapper) { + const templateMapper = appendTypeMapping(mapper, getTypeParameterFromMappedType(type), key); + const propType = instantiateType(getTemplateTypeFromMappedType(type.target as MappedType || type), templateMapper); + const modifiers = getMappedTypeModifiers(type); + return strictNullChecks && modifiers & MappedTypeModifiers.IncludeOptional && !maybeTypeOfKind(propType, TypeFlags.Undefined | TypeFlags.Void) ? getOptionalType(propType, /*isProperty*/ true) : + strictNullChecks && modifiers & MappedTypeModifiers.ExcludeOptional && isOptional ? getTypeWithFacts(propType, TypeFacts.NEUndefined) : + propType; + } + + function instantiateAnonymousType(type: AnonymousType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): AnonymousType { + Debug.assert(type.symbol, "anonymous type must have symbol to be instantiated"); + const result = createObjectType(type.objectFlags & ~(ObjectFlags.CouldContainTypeVariablesComputed | ObjectFlags.CouldContainTypeVariables) | ObjectFlags.Instantiated, type.symbol) as AnonymousType; + if (type.objectFlags & ObjectFlags.Mapped) { + (result as MappedType).declaration = (type as MappedType).declaration; + // C.f. instantiateSignature + const origTypeParameter = getTypeParameterFromMappedType(type as MappedType); + const freshTypeParameter = cloneTypeParameter(origTypeParameter); + (result as MappedType).typeParameter = freshTypeParameter; + mapper = combineTypeMappers(makeUnaryTypeMapper(origTypeParameter, freshTypeParameter), mapper); + freshTypeParameter.mapper = mapper; + } + if (type.objectFlags & ObjectFlags.InstantiationExpressionType) { + (result as InstantiationExpressionType).node = (type as InstantiationExpressionType).node; + } + if (type.objectFlags & ObjectFlags.SingleSignatureType) { + (result as SingleSignatureType).outerTypeParameters = (type as SingleSignatureType).outerTypeParameters; + } + result.target = type; + result.mapper = mapper; + result.aliasSymbol = aliasSymbol || type.aliasSymbol; + result.aliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + result.objectFlags |= result.aliasTypeArguments ? getPropagatingFlagsOfTypes(result.aliasTypeArguments) : 0; + return result; + } + + function getConditionalTypeInstantiation(type: ConditionalType, mapper: TypeMapper, forConstraint: boolean, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + const root = type.root; + if (root.outerTypeParameters) { + // We are instantiating a conditional type that has one or more type parameters in scope. Apply the + // mapper to the type parameters to produce the effective list of type arguments, and compute the + // instantiation cache key from the type IDs of the type arguments. + const typeArguments = map(root.outerTypeParameters, t => getMappedType(t, mapper)); + const id = (forConstraint ? "C" : "") + getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments); + let result = root.instantiations!.get(id); + if (!result) { + const newMapper = createTypeMapper(root.outerTypeParameters, typeArguments); + const checkType = root.checkType; + const distributionType = root.isDistributive ? getReducedType(getMappedType(checkType, newMapper)) : undefined; + // Distributive conditional types are distributed over union types. For example, when the + // distributive conditional type T extends U ? X : Y is instantiated with A | B for T, the + // result is (A extends U ? X : Y) | (B extends U ? X : Y). + result = distributionType && checkType !== distributionType && distributionType.flags & (TypeFlags.Union | TypeFlags.Never) ? + mapTypeWithAlias(distributionType, t => getConditionalType(root, prependTypeMapping(checkType, t, newMapper), forConstraint), aliasSymbol, aliasTypeArguments) : + getConditionalType(root, newMapper, forConstraint, aliasSymbol, aliasTypeArguments); + root.instantiations!.set(id, result); + } + return result; + } + return type; + } + + function instantiateType(type: Type, mapper: TypeMapper | undefined): Type; + function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined; + function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined { + return type && mapper ? instantiateTypeWithAlias(type, mapper, /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined) : type; + } + + function instantiateTypeWithAlias(type: Type, mapper: TypeMapper, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined): Type { + if (!couldContainTypeVariables(type)) { + return type; + } + if (instantiationDepth === 100 || instantiationCount >= 5000000) { + // We have reached 100 recursive type instantiations, or 5M type instantiations caused by the same statement + // or expression. There is a very high likelyhood we're dealing with a combination of infinite generic types + // that perpetually generate new type identities, so we stop the recursion here by yielding the error type. + tracing?.instant(tracing.Phase.CheckTypes, "instantiateType_DepthLimit", { typeId: type.id, instantiationDepth, instantiationCount }); + error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite); + return errorType; + } + totalInstantiationCount++; + instantiationCount++; + instantiationDepth++; + const result = instantiateTypeWorker(type, mapper, aliasSymbol, aliasTypeArguments); + instantiationDepth--; + return result; + } + + function instantiateTypeWorker(type: Type, mapper: TypeMapper, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined): Type { + const flags = type.flags; + if (flags & TypeFlags.TypeParameter) { + return getMappedType(type, mapper); + } + if (flags & TypeFlags.Object) { + const objectFlags = (type as ObjectType).objectFlags; + if (objectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous | ObjectFlags.Mapped)) { + if (objectFlags & ObjectFlags.Reference && !(type as TypeReference).node) { + const resolvedTypeArguments = (type as TypeReference).resolvedTypeArguments; + const newTypeArguments = instantiateTypes(resolvedTypeArguments, mapper); + return newTypeArguments !== resolvedTypeArguments ? createNormalizedTypeReference((type as TypeReference).target, newTypeArguments) : type; + } + if (objectFlags & ObjectFlags.ReverseMapped) { + return instantiateReverseMappedType(type as ReverseMappedType, mapper); + } + return getObjectTypeInstantiation(type as TypeReference | AnonymousType | MappedType, mapper, aliasSymbol, aliasTypeArguments); + } + return type; + } + if (flags & TypeFlags.UnionOrIntersection) { + const origin = type.flags & TypeFlags.Union ? (type as UnionType).origin : undefined; + const types = origin && origin.flags & TypeFlags.UnionOrIntersection ? (origin as UnionOrIntersectionType).types : (type as UnionOrIntersectionType).types; + const newTypes = instantiateTypes(types, mapper); + if (newTypes === types && aliasSymbol === type.aliasSymbol) { + return type; + } + const newAliasSymbol = aliasSymbol || type.aliasSymbol; + const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + return flags & TypeFlags.Intersection || origin && origin.flags & TypeFlags.Intersection ? + getIntersectionType(newTypes, IntersectionFlags.None, newAliasSymbol, newAliasTypeArguments) : + getUnionType(newTypes, UnionReduction.Literal, newAliasSymbol, newAliasTypeArguments); + } + if (flags & TypeFlags.Index) { + return getIndexType(instantiateType((type as IndexType).type, mapper)); + } + if (flags & TypeFlags.TemplateLiteral) { + return getTemplateLiteralType((type as TemplateLiteralType).texts, instantiateTypes((type as TemplateLiteralType).types, mapper)); + } + if (flags & TypeFlags.StringMapping) { + return getStringMappingType((type as StringMappingType).symbol, instantiateType((type as StringMappingType).type, mapper)); + } + if (flags & TypeFlags.IndexedAccess) { + const newAliasSymbol = aliasSymbol || type.aliasSymbol; + const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + return getIndexedAccessType(instantiateType((type as IndexedAccessType).objectType, mapper), instantiateType((type as IndexedAccessType).indexType, mapper), (type as IndexedAccessType).accessFlags, /*accessNode*/ undefined, newAliasSymbol, newAliasTypeArguments); + } + if (flags & TypeFlags.Conditional) { + return getConditionalTypeInstantiation(type as ConditionalType, combineTypeMappers((type as ConditionalType).mapper, mapper), /*forConstraint*/ false, aliasSymbol, aliasTypeArguments); + } + if (flags & TypeFlags.Substitution) { + const newBaseType = instantiateType((type as SubstitutionType).baseType, mapper); + if (isNoInferType(type)) { + return getNoInferType(newBaseType); + } + const newConstraint = instantiateType((type as SubstitutionType).constraint, mapper); + // A substitution type originates in the true branch of a conditional type and can be resolved + // to just the base type in the same cases as the conditional type resolves to its true branch + // (because the base type is then known to satisfy the constraint). + if (newBaseType.flags & TypeFlags.TypeVariable && isGenericType(newConstraint)) { + return getSubstitutionType(newBaseType, newConstraint); + } + if (newConstraint.flags & TypeFlags.AnyOrUnknown || isTypeAssignableTo(getRestrictiveInstantiation(newBaseType), getRestrictiveInstantiation(newConstraint))) { + return newBaseType; + } + return newBaseType.flags & TypeFlags.TypeVariable ? getSubstitutionType(newBaseType, newConstraint) : getIntersectionType([newConstraint, newBaseType]); + } + return type; + } + + function instantiateReverseMappedType(type: ReverseMappedType, mapper: TypeMapper) { + const innerMappedType = instantiateType(type.mappedType, mapper); + if (!(getObjectFlags(innerMappedType) & ObjectFlags.Mapped)) { + return type; + } + const innerIndexType = instantiateType(type.constraintType, mapper); + if (!(innerIndexType.flags & TypeFlags.Index)) { + return type; + } + const instantiated = inferTypeForHomomorphicMappedType( + instantiateType(type.source, mapper), + innerMappedType as MappedType, + innerIndexType as IndexType, + ); + if (instantiated) { + return instantiated; + } + return type; // Nested invocation of `inferTypeForHomomorphicMappedType` or the `source` instantiated into something unmappable + } + + function getPermissiveInstantiation(type: Type) { + return type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never) ? type : + type.permissiveInstantiation || (type.permissiveInstantiation = instantiateType(type, permissiveMapper)); + } + + function getRestrictiveInstantiation(type: Type) { + if (type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never)) { + return type; + } + if (type.restrictiveInstantiation) { + return type.restrictiveInstantiation; + } + type.restrictiveInstantiation = instantiateType(type, restrictiveMapper); + // We set the following so we don't attempt to set the restrictive instance of a restrictive instance + // which is redundant - we'll produce new type identities, but all type params have already been mapped. + // This also gives us a way to detect restrictive instances upon comparisons and _disable_ the "distributeive constraint" + // assignability check for them, which is distinctly unsafe, as once you have a restrctive instance, all the type parameters + // are constrained to `unknown` and produce tons of false positives/negatives! + type.restrictiveInstantiation.restrictiveInstantiation = type.restrictiveInstantiation; + return type.restrictiveInstantiation; + } + + function instantiateIndexInfo(info: IndexInfo, mapper: TypeMapper) { + return createIndexInfo(info.keyType, instantiateType(info.type, mapper), info.isReadonly, info.declaration); + } + + // Returns true if the given expression contains (at any level of nesting) a function or arrow expression + // that is subject to contextual typing. + function isContextSensitive(node: Expression | MethodDeclaration | ObjectLiteralElementLike | JsxAttributeLike | JsxChild): boolean { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + switch (node.kind) { + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.FunctionDeclaration: // Function declarations can have context when annotated with a jsdoc @type + return isContextSensitiveFunctionLikeDeclaration(node as FunctionExpression | ArrowFunction | MethodDeclaration); + case SyntaxKind.ObjectLiteralExpression: + return some((node as ObjectLiteralExpression).properties, isContextSensitive); + case SyntaxKind.ArrayLiteralExpression: + return some((node as ArrayLiteralExpression).elements, isContextSensitive); + case SyntaxKind.ConditionalExpression: + return isContextSensitive((node as ConditionalExpression).whenTrue) || + isContextSensitive((node as ConditionalExpression).whenFalse); + case SyntaxKind.BinaryExpression: + return ((node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken || (node as BinaryExpression).operatorToken.kind === SyntaxKind.QuestionQuestionToken) && + (isContextSensitive((node as BinaryExpression).left) || isContextSensitive((node as BinaryExpression).right)); + case SyntaxKind.PropertyAssignment: + return isContextSensitive((node as PropertyAssignment).initializer); + case SyntaxKind.ParenthesizedExpression: + return isContextSensitive((node as ParenthesizedExpression).expression); + case SyntaxKind.JsxAttributes: + return some((node as JsxAttributes).properties, isContextSensitive) || isJsxOpeningElement(node.parent) && some(node.parent.parent.children, isContextSensitive); + case SyntaxKind.JsxAttribute: { + // If there is no initializer, JSX attribute has a boolean value of true which is not context sensitive. + const { initializer } = node as JsxAttribute; + return !!initializer && isContextSensitive(initializer); + } + case SyntaxKind.JsxExpression: { + // It is possible to that node.expression is undefined (e.g

) + const { expression } = node as JsxExpression; + return !!expression && isContextSensitive(expression); + } + } + + return false; + } + + function isContextSensitiveFunctionLikeDeclaration(node: FunctionLikeDeclaration): boolean { + return hasContextSensitiveParameters(node) || hasContextSensitiveReturnExpression(node); + } + + function hasContextSensitiveReturnExpression(node: FunctionLikeDeclaration) { + if (node.typeParameters || getEffectiveReturnTypeNode(node) || !node.body) { + return false; + } + if (node.body.kind !== SyntaxKind.Block) { + return isContextSensitive(node.body); + } + return !!forEachReturnStatement(node.body as Block, statement => !!statement.expression && isContextSensitive(statement.expression)); + } + + function isContextSensitiveFunctionOrObjectLiteralMethod(func: Node): func is FunctionExpression | ArrowFunction | MethodDeclaration { + return (isFunctionExpressionOrArrowFunction(func) || isObjectLiteralMethod(func)) && + isContextSensitiveFunctionLikeDeclaration(func); + } + + function getTypeWithoutSignatures(type: Type): Type { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + if (resolved.constructSignatures.length || resolved.callSignatures.length) { + const result = createObjectType(ObjectFlags.Anonymous, type.symbol); + result.members = resolved.members; + result.properties = resolved.properties; + result.callSignatures = emptyArray; + result.constructSignatures = emptyArray; + result.indexInfos = emptyArray; + return result; + } + } + else if (type.flags & TypeFlags.Intersection) { + return getIntersectionType(map((type as IntersectionType).types, getTypeWithoutSignatures)); + } + return type; + } + + // TYPE CHECKING + + function isTypeIdenticalTo(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, identityRelation); + } + + function compareTypesIdentical(source: Type, target: Type): Ternary { + return isTypeRelatedTo(source, target, identityRelation) ? Ternary.True : Ternary.False; + } + + function compareTypesAssignable(source: Type, target: Type): Ternary { + return isTypeRelatedTo(source, target, assignableRelation) ? Ternary.True : Ternary.False; + } + + function compareTypesSubtypeOf(source: Type, target: Type): Ternary { + return isTypeRelatedTo(source, target, subtypeRelation) ? Ternary.True : Ternary.False; + } + + function isTypeSubtypeOf(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, subtypeRelation); + } + + function isTypeStrictSubtypeOf(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, strictSubtypeRelation); + } + + function isTypeAssignableTo(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, assignableRelation); + } + + // An object type S is considered to be derived from an object type T if + // S is a union type and every constituent of S is derived from T, + // T is a union type and S is derived from at least one constituent of T, or + // S is an intersection type and some constituent of S is derived from T, or + // S is a type variable with a base constraint that is derived from T, or + // T is {} and S is an object-like type (ensuring {} is less derived than Object), or + // T is one of the global types Object and Function and S is a subtype of T, or + // T occurs directly or indirectly in an 'extends' clause of S. + // Note that this check ignores type parameters and only considers the + // inheritance hierarchy. + function isTypeDerivedFrom(source: Type, target: Type): boolean { + return source.flags & TypeFlags.Union ? every((source as UnionType).types, t => isTypeDerivedFrom(t, target)) : + target.flags & TypeFlags.Union ? some((target as UnionType).types, t => isTypeDerivedFrom(source, t)) : + source.flags & TypeFlags.Intersection ? some((source as IntersectionType).types, t => isTypeDerivedFrom(t, target)) : + source.flags & TypeFlags.InstantiableNonPrimitive ? isTypeDerivedFrom(getBaseConstraintOfType(source) || unknownType, target) : + isEmptyAnonymousObjectType(target) ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) : + target === globalObjectType ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) && !isEmptyAnonymousObjectType(source) : + target === globalFunctionType ? !!(source.flags & TypeFlags.Object) && isFunctionObjectType(source as ObjectType) : + hasBaseType(source, getTargetType(target)) || (isArrayType(target) && !isReadonlyArrayType(target) && isTypeDerivedFrom(source, globalReadonlyArrayType)); + } + + /** + * This is *not* a bi-directional relationship. + * If one needs to check both directions for comparability, use a second call to this function or 'checkTypeComparableTo'. + * + * A type S is comparable to a type T if some (but not necessarily all) of the possible values of S are also possible values of T. + * It is used to check following cases: + * - the types of the left and right sides of equality/inequality operators (`===`, `!==`, `==`, `!=`). + * - the types of `case` clause expressions and their respective `switch` expressions. + * - the type of an expression in a type assertion with the type being asserted. + */ + function isTypeComparableTo(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, comparableRelation); + } + + function areTypesComparable(type1: Type, type2: Type): boolean { + return isTypeComparableTo(type1, type2) || isTypeComparableTo(type2, type1); + } + + function checkTypeAssignableTo(source: Type, target: Type, errorNode: Node | undefined, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined, errorOutputObject?: { errors?: Diagnostic[]; }): boolean { + return checkTypeRelatedTo(source, target, assignableRelation, errorNode, headMessage, containingMessageChain, errorOutputObject); + } + + /** + * Like `checkTypeAssignableTo`, but if it would issue an error, instead performs structural comparisons of the types using the given expression node to + * attempt to issue more specific errors on, for example, specific object literal properties or tuple members. + */ + function checkTypeAssignableToAndOptionallyElaborate(source: Type, target: Type, errorNode: Node | undefined, expr: Expression | undefined, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined): boolean { + return checkTypeRelatedToAndOptionallyElaborate(source, target, assignableRelation, errorNode, expr, headMessage, containingMessageChain, /*errorOutputContainer*/ undefined); + } + + function checkTypeRelatedToAndOptionallyElaborate( + source: Type, + target: Type, + relation: Map, + errorNode: Node | undefined, + expr: Expression | undefined, + headMessage: DiagnosticMessage | undefined, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + if (isTypeRelatedTo(source, target, relation)) return true; + if (!errorNode || !elaborateError(expr, source, target, relation, headMessage, containingMessageChain, errorOutputContainer)) { + return checkTypeRelatedTo(source, target, relation, errorNode, headMessage, containingMessageChain, errorOutputContainer); + } + return false; + } + + function isOrHasGenericConditional(type: Type): boolean { + return !!(type.flags & TypeFlags.Conditional || (type.flags & TypeFlags.Intersection && some((type as IntersectionType).types, isOrHasGenericConditional))); + } + + function elaborateError( + node: Expression | undefined, + source: Type, + target: Type, + relation: Map, + headMessage: DiagnosticMessage | undefined, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + if (!node || isOrHasGenericConditional(target)) return false; + if ( + !checkTypeRelatedTo(source, target, relation, /*errorNode*/ undefined) + && elaborateDidYouMeanToCallOrConstruct(node, source, target, relation, headMessage, containingMessageChain, errorOutputContainer) + ) { + return true; + } + switch (node.kind) { + case SyntaxKind.AsExpression: + if (!isConstAssertion(node)) { + break; + } + // fallthrough + case SyntaxKind.JsxExpression: + case SyntaxKind.ParenthesizedExpression: + return elaborateError((node as AsExpression | ParenthesizedExpression | JsxExpression).expression, source, target, relation, headMessage, containingMessageChain, errorOutputContainer); + case SyntaxKind.BinaryExpression: + switch ((node as BinaryExpression).operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.CommaToken: + return elaborateError((node as BinaryExpression).right, source, target, relation, headMessage, containingMessageChain, errorOutputContainer); + } + break; + case SyntaxKind.ObjectLiteralExpression: + return elaborateObjectLiteral(node as ObjectLiteralExpression, source, target, relation, containingMessageChain, errorOutputContainer); + case SyntaxKind.ArrayLiteralExpression: + return elaborateArrayLiteral(node as ArrayLiteralExpression, source, target, relation, containingMessageChain, errorOutputContainer); + case SyntaxKind.JsxAttributes: + return elaborateJsxComponents(node as JsxAttributes, source, target, relation, containingMessageChain, errorOutputContainer); + case SyntaxKind.ArrowFunction: + return elaborateArrowFunction(node as ArrowFunction, source, target, relation, containingMessageChain, errorOutputContainer); + } + return false; + } + + function elaborateDidYouMeanToCallOrConstruct( + node: Expression, + source: Type, + target: Type, + relation: Map, + headMessage: DiagnosticMessage | undefined, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + const callSignatures = getSignaturesOfType(source, SignatureKind.Call); + const constructSignatures = getSignaturesOfType(source, SignatureKind.Construct); + for (const signatures of [constructSignatures, callSignatures]) { + if ( + some(signatures, s => { + const returnType = getReturnTypeOfSignature(s); + return !(returnType.flags & (TypeFlags.Any | TypeFlags.Never)) && checkTypeRelatedTo(returnType, target, relation, /*errorNode*/ undefined); + }) + ) { + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + checkTypeAssignableTo(source, target, node, headMessage, containingMessageChain, resultObj); + const diagnostic = resultObj.errors![resultObj.errors!.length - 1]; + addRelatedInfo( + diagnostic, + createDiagnosticForNode( + node, + signatures === constructSignatures ? Diagnostics.Did_you_mean_to_use_new_with_this_expression : Diagnostics.Did_you_mean_to_call_this_expression, + ), + ); + return true; + } + } + return false; + } + + function elaborateArrowFunction( + node: ArrowFunction, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + // Don't elaborate blocks + if (isBlock(node.body)) { + return false; + } + // Or functions with annotated parameter types + if (some(node.parameters, hasType)) { + return false; + } + const sourceSig = getSingleCallSignature(source); + if (!sourceSig) { + return false; + } + const targetSignatures = getSignaturesOfType(target, SignatureKind.Call); + if (!length(targetSignatures)) { + return false; + } + const returnExpression = node.body; + const sourceReturn = getReturnTypeOfSignature(sourceSig); + const targetReturn = getUnionType(map(targetSignatures, getReturnTypeOfSignature)); + if (!checkTypeRelatedTo(sourceReturn, targetReturn, relation, /*errorNode*/ undefined)) { + const elaborated = returnExpression && elaborateError(returnExpression, sourceReturn, targetReturn, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); + if (elaborated) { + return elaborated; + } + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + checkTypeRelatedTo(sourceReturn, targetReturn, relation, returnExpression, /*headMessage*/ undefined, containingMessageChain, resultObj); + if (resultObj.errors) { + if (target.symbol && length(target.symbol.declarations)) { + addRelatedInfo( + resultObj.errors[resultObj.errors.length - 1], + createDiagnosticForNode( + target.symbol.declarations![0], + Diagnostics.The_expected_type_comes_from_the_return_type_of_this_signature, + ), + ); + } + if ( + (getFunctionFlags(node) & FunctionFlags.Async) === 0 + // exclude cases where source itself is promisy - this way we don't make a suggestion when relating + // an IPromise and a Promise that are slightly different + && !getTypeOfPropertyOfType(sourceReturn, "then" as __String) + && checkTypeRelatedTo(createPromiseType(sourceReturn), targetReturn, relation, /*errorNode*/ undefined) + ) { + addRelatedInfo( + resultObj.errors[resultObj.errors.length - 1], + createDiagnosticForNode( + node, + Diagnostics.Did_you_mean_to_mark_this_function_as_async, + ), + ); + } + return true; + } + } + return false; + } + + function getBestMatchIndexedAccessTypeOrUndefined(source: Type, target: Type, nameType: Type) { + const idx = getIndexedAccessTypeOrUndefined(target, nameType); + if (idx) { + return idx; + } + if (target.flags & TypeFlags.Union) { + const best = getBestMatchingType(source, target as UnionType); + if (best) { + return getIndexedAccessTypeOrUndefined(best, nameType); + } + } + } + + function checkExpressionForMutableLocationWithContextualType(next: Expression, sourcePropType: Type) { + pushContextualType(next, sourcePropType, /*isCache*/ false); + const result = checkExpressionForMutableLocation(next, CheckMode.Contextual); + popContextualType(); + return result; + } + + type ElaborationIterator = IterableIterator<{ errorNode: Node; innerExpression: Expression | undefined; nameType: Type; errorMessage?: DiagnosticMessage | undefined; }>; + /** + * For every element returned from the iterator, checks that element to issue an error on a property of that element's type + * If that element would issue an error, we first attempt to dive into that element's inner expression and issue a more specific error by recuring into `elaborateError` + * Otherwise, we issue an error on _every_ element which fail the assignability check + */ + function elaborateElementwise( + iterator: ElaborationIterator, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + // Assignability failure - check each prop individually, and if that fails, fall back on the bad error span + let reportedError = false; + for (const value of iterator) { + const { errorNode: prop, innerExpression: next, nameType, errorMessage } = value; + let targetPropType = getBestMatchIndexedAccessTypeOrUndefined(source, target, nameType); + if (!targetPropType || targetPropType.flags & TypeFlags.IndexedAccess) continue; // Don't elaborate on indexes on generic variables + let sourcePropType = getIndexedAccessTypeOrUndefined(source, nameType); + if (!sourcePropType) continue; + const propName = getPropertyNameFromIndex(nameType, /*accessNode*/ undefined); + if (!checkTypeRelatedTo(sourcePropType, targetPropType, relation, /*errorNode*/ undefined)) { + const elaborated = next && elaborateError(next, sourcePropType, targetPropType, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); + reportedError = true; + if (!elaborated) { + // Issue error on the prop itself, since the prop couldn't elaborate the error + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + // Use the expression type, if available + const specificSource = next ? checkExpressionForMutableLocationWithContextualType(next, sourcePropType) : sourcePropType; + if (exactOptionalPropertyTypes && isExactOptionalPropertyMismatch(specificSource, targetPropType)) { + const diag = createDiagnosticForNode(prop, Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target, typeToString(specificSource), typeToString(targetPropType)); + diagnostics.add(diag); + resultObj.errors = [diag]; + } + else { + const targetIsOptional = !!(propName && (getPropertyOfType(target, propName) || unknownSymbol).flags & SymbolFlags.Optional); + const sourceIsOptional = !!(propName && (getPropertyOfType(source, propName) || unknownSymbol).flags & SymbolFlags.Optional); + targetPropType = removeMissingType(targetPropType, targetIsOptional); + sourcePropType = removeMissingType(sourcePropType, targetIsOptional && sourceIsOptional); + const result = checkTypeRelatedTo(specificSource, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + if (result && specificSource !== sourcePropType) { + // If for whatever reason the expression type doesn't yield an error, make sure we still issue an error on the sourcePropType + checkTypeRelatedTo(sourcePropType, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + } + } + if (resultObj.errors) { + const reportedDiag = resultObj.errors[resultObj.errors.length - 1]; + const propertyName = isTypeUsableAsPropertyName(nameType) ? getPropertyNameFromType(nameType) : undefined; + const targetProp = propertyName !== undefined ? getPropertyOfType(target, propertyName) : undefined; + + let issuedElaboration = false; + if (!targetProp) { + const indexInfo = getApplicableIndexInfo(target, nameType); + if (indexInfo && indexInfo.declaration && !getSourceFileOfNode(indexInfo.declaration).hasNoDefaultLib) { + issuedElaboration = true; + addRelatedInfo(reportedDiag, createDiagnosticForNode(indexInfo.declaration, Diagnostics.The_expected_type_comes_from_this_index_signature)); + } + } + + if (!issuedElaboration && (targetProp && length(targetProp.declarations) || target.symbol && length(target.symbol.declarations))) { + const targetNode = targetProp && length(targetProp.declarations) ? targetProp.declarations![0] : target.symbol.declarations![0]; + if (!getSourceFileOfNode(targetNode).hasNoDefaultLib) { + addRelatedInfo( + reportedDiag, + createDiagnosticForNode( + targetNode, + Diagnostics.The_expected_type_comes_from_property_0_which_is_declared_here_on_type_1, + propertyName && !(nameType.flags & TypeFlags.UniqueESSymbol) ? unescapeLeadingUnderscores(propertyName) : typeToString(nameType), + typeToString(target), + ), + ); + } + } + } + } + } + } + return reportedError; + } + + /** + * Assumes `target` type is assignable to the `Iterable` type, if `Iterable` is defined, + * or that it's an array or tuple-like type, if `Iterable` is not defined. + */ + function elaborateIterableOrArrayLikeTargetElementwise( + iterator: ElaborationIterator, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + const tupleOrArrayLikeTargetParts = filterType(target, isArrayOrTupleLikeType); + const nonTupleOrArrayLikeTargetParts = filterType(target, t => !isArrayOrTupleLikeType(t)); + // If `nonTupleOrArrayLikeTargetParts` is not `never`, then that should mean `Iterable` is defined. + const iterationType = nonTupleOrArrayLikeTargetParts !== neverType + ? getIterationTypeOfIterable(IterationUse.ForOf, IterationTypeKind.Yield, nonTupleOrArrayLikeTargetParts, /*errorNode*/ undefined) + : undefined; + + let reportedError = false; + for (let status = iterator.next(); !status.done; status = iterator.next()) { + const { errorNode: prop, innerExpression: next, nameType, errorMessage } = status.value; + let targetPropType = iterationType; + const targetIndexedPropType = tupleOrArrayLikeTargetParts !== neverType ? getBestMatchIndexedAccessTypeOrUndefined(source, tupleOrArrayLikeTargetParts, nameType) : undefined; + if (targetIndexedPropType && !(targetIndexedPropType.flags & TypeFlags.IndexedAccess)) { // Don't elaborate on indexes on generic variables + targetPropType = iterationType ? getUnionType([iterationType, targetIndexedPropType]) : targetIndexedPropType; + } + if (!targetPropType) continue; + let sourcePropType = getIndexedAccessTypeOrUndefined(source, nameType); + if (!sourcePropType) continue; + const propName = getPropertyNameFromIndex(nameType, /*accessNode*/ undefined); + if (!checkTypeRelatedTo(sourcePropType, targetPropType, relation, /*errorNode*/ undefined)) { + const elaborated = next && elaborateError(next, sourcePropType, targetPropType, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); + reportedError = true; + if (!elaborated) { + // Issue error on the prop itself, since the prop couldn't elaborate the error + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + // Use the expression type, if available + const specificSource = next ? checkExpressionForMutableLocationWithContextualType(next, sourcePropType) : sourcePropType; + if (exactOptionalPropertyTypes && isExactOptionalPropertyMismatch(specificSource, targetPropType)) { + const diag = createDiagnosticForNode(prop, Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target, typeToString(specificSource), typeToString(targetPropType)); + diagnostics.add(diag); + resultObj.errors = [diag]; + } + else { + const targetIsOptional = !!(propName && (getPropertyOfType(tupleOrArrayLikeTargetParts, propName) || unknownSymbol).flags & SymbolFlags.Optional); + const sourceIsOptional = !!(propName && (getPropertyOfType(source, propName) || unknownSymbol).flags & SymbolFlags.Optional); + targetPropType = removeMissingType(targetPropType, targetIsOptional); + sourcePropType = removeMissingType(sourcePropType, targetIsOptional && sourceIsOptional); + const result = checkTypeRelatedTo(specificSource, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + if (result && specificSource !== sourcePropType) { + // If for whatever reason the expression type doesn't yield an error, make sure we still issue an error on the sourcePropType + checkTypeRelatedTo(sourcePropType, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + } + } + } + } + } + return reportedError; + } + + function* generateJsxAttributes(node: JsxAttributes): ElaborationIterator { + if (!length(node.properties)) return; + for (const prop of node.properties) { + if (isJsxSpreadAttribute(prop) || isHyphenatedJsxName(getTextOfJsxAttributeName(prop.name))) continue; + yield { errorNode: prop.name, innerExpression: prop.initializer, nameType: getStringLiteralType(getTextOfJsxAttributeName(prop.name)) }; + } + } + + function* generateJsxChildren(node: JsxElement, getInvalidTextDiagnostic: () => DiagnosticMessage): ElaborationIterator { + if (!length(node.children)) return; + let memberOffset = 0; + for (let i = 0; i < node.children.length; i++) { + const child = node.children[i]; + const nameType = getNumberLiteralType(i - memberOffset); + const elem = getElaborationElementForJsxChild(child, nameType, getInvalidTextDiagnostic); + if (elem) { + yield elem; + } + else { + memberOffset++; + } + } + } + + function getElaborationElementForJsxChild(child: JsxChild, nameType: LiteralType, getInvalidTextDiagnostic: () => DiagnosticMessage) { + switch (child.kind) { + case SyntaxKind.JsxExpression: + // child is of the type of the expression + return { errorNode: child, innerExpression: child.expression, nameType }; + case SyntaxKind.JsxText: + if (child.containsOnlyTriviaWhiteSpaces) { + break; // Whitespace only jsx text isn't real jsx text + } + // child is a string + return { errorNode: child, innerExpression: undefined, nameType, errorMessage: getInvalidTextDiagnostic() }; + case SyntaxKind.JsxElement: + case SyntaxKind.JsxSelfClosingElement: + case SyntaxKind.JsxFragment: + // child is of type JSX.Element + return { errorNode: child, innerExpression: child, nameType }; + default: + return Debug.assertNever(child, "Found invalid jsx child"); + } + } + + function elaborateJsxComponents( + node: JsxAttributes, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + let result = elaborateElementwise(generateJsxAttributes(node), source, target, relation, containingMessageChain, errorOutputContainer); + let invalidTextDiagnostic: DiagnosticMessage | undefined; + if (isJsxOpeningElement(node.parent) && isJsxElement(node.parent.parent)) { + const containingElement = node.parent.parent; + const childPropName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + const childrenPropName = childPropName === undefined ? "children" : unescapeLeadingUnderscores(childPropName); + const childrenNameType = getStringLiteralType(childrenPropName); + const childrenTargetType = getIndexedAccessType(target, childrenNameType); + const validChildren = getSemanticJsxChildren(containingElement.children); + if (!length(validChildren)) { + return result; + } + const moreThanOneRealChildren = length(validChildren) > 1; + let arrayLikeTargetParts: Type; + let nonArrayLikeTargetParts: Type; + const iterableType = getGlobalIterableType(/*reportErrors*/ false); + if (iterableType !== emptyGenericType) { + const anyIterable = createIterableType(anyType); + arrayLikeTargetParts = filterType(childrenTargetType, t => isTypeAssignableTo(t, anyIterable)); + nonArrayLikeTargetParts = filterType(childrenTargetType, t => !isTypeAssignableTo(t, anyIterable)); + } + else { + arrayLikeTargetParts = filterType(childrenTargetType, isArrayOrTupleLikeType); + nonArrayLikeTargetParts = filterType(childrenTargetType, t => !isArrayOrTupleLikeType(t)); + } + if (moreThanOneRealChildren) { + if (arrayLikeTargetParts !== neverType) { + const realSource = createTupleType(checkJsxChildren(containingElement, CheckMode.Normal)); + const children = generateJsxChildren(containingElement, getInvalidTextualChildDiagnostic); + result = elaborateIterableOrArrayLikeTargetElementwise(children, realSource, arrayLikeTargetParts, relation, containingMessageChain, errorOutputContainer) || result; + } + else if (!isTypeRelatedTo(getIndexedAccessType(source, childrenNameType), childrenTargetType, relation)) { + // arity mismatch + result = true; + const diag = error( + containingElement.openingElement.tagName, + Diagnostics.This_JSX_tag_s_0_prop_expects_a_single_child_of_type_1_but_multiple_children_were_provided, + childrenPropName, + typeToString(childrenTargetType), + ); + if (errorOutputContainer && errorOutputContainer.skipLogging) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + } + } + else { + if (nonArrayLikeTargetParts !== neverType) { + const child = validChildren[0]; + const elem = getElaborationElementForJsxChild(child, childrenNameType, getInvalidTextualChildDiagnostic); + if (elem) { + result = elaborateElementwise( + (function* () { + yield elem; + })(), + source, + target, + relation, + containingMessageChain, + errorOutputContainer, + ) || result; + } + } + else if (!isTypeRelatedTo(getIndexedAccessType(source, childrenNameType), childrenTargetType, relation)) { + // arity mismatch + result = true; + const diag = error( + containingElement.openingElement.tagName, + Diagnostics.This_JSX_tag_s_0_prop_expects_type_1_which_requires_multiple_children_but_only_a_single_child_was_provided, + childrenPropName, + typeToString(childrenTargetType), + ); + if (errorOutputContainer && errorOutputContainer.skipLogging) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + } + } + } + return result; + + function getInvalidTextualChildDiagnostic() { + if (!invalidTextDiagnostic) { + const tagNameText = getTextOfNode(node.parent.tagName); + const childPropName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + const childrenPropName = childPropName === undefined ? "children" : unescapeLeadingUnderscores(childPropName); + const childrenTargetType = getIndexedAccessType(target, getStringLiteralType(childrenPropName)); + const diagnostic = Diagnostics._0_components_don_t_accept_text_as_child_elements_Text_in_JSX_has_the_type_string_but_the_expected_type_of_1_is_2; + invalidTextDiagnostic = { ...diagnostic, key: "!!ALREADY FORMATTED!!", message: formatMessage(diagnostic, tagNameText, childrenPropName, typeToString(childrenTargetType)) }; + } + return invalidTextDiagnostic; + } + } + + function* generateLimitedTupleElements(node: ArrayLiteralExpression, target: Type): ElaborationIterator { + const len = length(node.elements); + if (!len) return; + for (let i = 0; i < len; i++) { + // Skip elements which do not exist in the target - a length error on the tuple overall is likely better than an error on a mismatched index signature + if (isTupleLikeType(target) && !getPropertyOfType(target, ("" + i) as __String)) continue; + const elem = node.elements[i]; + if (isOmittedExpression(elem)) continue; + const nameType = getNumberLiteralType(i); + const checkNode = getEffectiveCheckNode(elem); + yield { errorNode: checkNode, innerExpression: checkNode, nameType }; + } + } + + function elaborateArrayLiteral( + node: ArrayLiteralExpression, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + if (target.flags & (TypeFlags.Primitive | TypeFlags.Never)) return false; + if (isTupleLikeType(source)) { + return elaborateElementwise(generateLimitedTupleElements(node, target), source, target, relation, containingMessageChain, errorOutputContainer); + } + // recreate a tuple from the elements, if possible + // Since we're re-doing the expression type, we need to reapply the contextual type + pushContextualType(node, target, /*isCache*/ false); + const tupleizedType = checkArrayLiteral(node, CheckMode.Contextual, /*forceTuple*/ true); + popContextualType(); + if (isTupleLikeType(tupleizedType)) { + return elaborateElementwise(generateLimitedTupleElements(node, target), tupleizedType, target, relation, containingMessageChain, errorOutputContainer); + } + return false; + } + + function* generateObjectLiteralElements(node: ObjectLiteralExpression): ElaborationIterator { + if (!length(node.properties)) return; + for (const prop of node.properties) { + if (isSpreadAssignment(prop)) continue; + const type = getLiteralTypeFromProperty(getSymbolOfDeclaration(prop), TypeFlags.StringOrNumberLiteralOrUnique); + if (!type || (type.flags & TypeFlags.Never)) { + continue; + } + switch (prop.kind) { + case SyntaxKind.SetAccessor: + case SyntaxKind.GetAccessor: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.ShorthandPropertyAssignment: + yield { errorNode: prop.name, innerExpression: undefined, nameType: type }; + break; + case SyntaxKind.PropertyAssignment: + yield { errorNode: prop.name, innerExpression: prop.initializer, nameType: type, errorMessage: isComputedNonLiteralName(prop.name) ? Diagnostics.Type_of_computed_property_s_value_is_0_which_is_not_assignable_to_type_1 : undefined }; + break; + default: + Debug.assertNever(prop); + } + } + } + + function elaborateObjectLiteral( + node: ObjectLiteralExpression, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + if (target.flags & (TypeFlags.Primitive | TypeFlags.Never)) return false; + return elaborateElementwise(generateObjectLiteralElements(node), source, target, relation, containingMessageChain, errorOutputContainer); + } + + /** + * This is *not* a bi-directional relationship. + * If one needs to check both directions for comparability, use a second call to this function or 'isTypeComparableTo'. + */ + function checkTypeComparableTo(source: Type, target: Type, errorNode: Node, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined): boolean { + return checkTypeRelatedTo(source, target, comparableRelation, errorNode, headMessage, containingMessageChain); + } + + function isSignatureAssignableTo(source: Signature, target: Signature, ignoreReturnTypes: boolean): boolean { + return compareSignaturesRelated(source, target, ignoreReturnTypes ? SignatureCheckMode.IgnoreReturnTypes : SignatureCheckMode.None, /*reportErrors*/ false, /*errorReporter*/ undefined, /*incompatibleErrorReporter*/ undefined, compareTypesAssignable, /*reportUnreliableMarkers*/ undefined) !== Ternary.False; + } + + type ErrorReporter = (message: DiagnosticMessage, ...args: DiagnosticArguments) => void; + + /** + * Returns true if `s` is `(...args: A) => R` where `A` is `any`, `any[]`, `never`, or `never[]`, and `R` is `any` or `unknown`. + */ + function isTopSignature(s: Signature) { + if (!s.typeParameters && (!s.thisParameter || isTypeAny(getTypeOfParameter(s.thisParameter))) && s.parameters.length === 1 && signatureHasRestParameter(s)) { + const paramType = getTypeOfParameter(s.parameters[0]); + const restType = isArrayType(paramType) ? getTypeArguments(paramType)[0] : paramType; + return !!(restType.flags & (TypeFlags.Any | TypeFlags.Never) && getReturnTypeOfSignature(s).flags & TypeFlags.AnyOrUnknown); + } + return false; + } + + /** + * See signatureRelatedTo, compareSignaturesIdentical + */ + function compareSignaturesRelated(source: Signature, target: Signature, checkMode: SignatureCheckMode, reportErrors: boolean, errorReporter: ErrorReporter | undefined, incompatibleErrorReporter: ((source: Type, target: Type) => void) | undefined, compareTypes: TypeComparer, reportUnreliableMarkers: TypeMapper | undefined): Ternary { + // TODO (drosen): De-duplicate code between related functions. + if (source === target) { + return Ternary.True; + } + + if (!(checkMode & SignatureCheckMode.StrictTopSignature && isTopSignature(source)) && isTopSignature(target)) { + return Ternary.True; + } + if (checkMode & SignatureCheckMode.StrictTopSignature && isTopSignature(source) && !isTopSignature(target)) { + return Ternary.False; + } + + const targetCount = getParameterCount(target); + const sourceHasMoreParameters = !hasEffectiveRestParameter(target) && + (checkMode & SignatureCheckMode.StrictArity ? hasEffectiveRestParameter(source) || getParameterCount(source) > targetCount : getMinArgumentCount(source) > targetCount); + if (sourceHasMoreParameters) { + if (reportErrors && !(checkMode & SignatureCheckMode.StrictArity)) { + // the second condition should be redundant, because there is no error reporting when comparing signatures by strict arity + // since it is only done for subtype reduction + errorReporter!(Diagnostics.Target_signature_provides_too_few_arguments_Expected_0_or_more_but_got_1, getMinArgumentCount(source), targetCount); + } + return Ternary.False; + } + + if (source.typeParameters && source.typeParameters !== target.typeParameters) { + target = getCanonicalSignature(target); + source = instantiateSignatureInContextOf(source, target, /*inferenceContext*/ undefined, compareTypes); + } + + const sourceCount = getParameterCount(source); + const sourceRestType = getNonArrayRestType(source); + const targetRestType = getNonArrayRestType(target); + if (sourceRestType || targetRestType) { + void instantiateType(sourceRestType || targetRestType, reportUnreliableMarkers); + } + + const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown; + const strictVariance = !(checkMode & SignatureCheckMode.Callback) && strictFunctionTypes && kind !== SyntaxKind.MethodDeclaration && + kind !== SyntaxKind.MethodSignature && kind !== SyntaxKind.Constructor; + let result = Ternary.True; + + const sourceThisType = getThisTypeOfSignature(source); + if (sourceThisType && sourceThisType !== voidType) { + const targetThisType = getThisTypeOfSignature(target); + if (targetThisType) { + // void sources are assignable to anything. + const related = !strictVariance && compareTypes(sourceThisType, targetThisType, /*reportErrors*/ false) + || compareTypes(targetThisType, sourceThisType, reportErrors); + if (!related) { + if (reportErrors) { + errorReporter!(Diagnostics.The_this_types_of_each_signature_are_incompatible); + } + return Ternary.False; + } + result &= related; + } + } + + const paramCount = sourceRestType || targetRestType ? Math.min(sourceCount, targetCount) : Math.max(sourceCount, targetCount); + const restIndex = sourceRestType || targetRestType ? paramCount - 1 : -1; + + for (let i = 0; i < paramCount; i++) { + const sourceType = i === restIndex ? getRestOrAnyTypeAtPosition(source, i) : tryGetTypeAtPosition(source, i); + const targetType = i === restIndex ? getRestOrAnyTypeAtPosition(target, i) : tryGetTypeAtPosition(target, i); + if (sourceType && targetType && (sourceType !== targetType || checkMode & SignatureCheckMode.StrictArity)) { + // In order to ensure that any generic type Foo is at least co-variant with respect to T no matter + // how Foo uses T, we need to relate parameters bi-variantly (given that parameters are input positions, + // they naturally relate only contra-variantly). However, if the source and target parameters both have + // function types with a single call signature, we know we are relating two callback parameters. In + // that case it is sufficient to only relate the parameters of the signatures co-variantly because, + // similar to return values, callback parameters are output positions. This means that a Promise, + // where T is used only in callback parameter positions, will be co-variant (as opposed to bi-variant) + // with respect to T. + const sourceSig = checkMode & SignatureCheckMode.Callback || isInstantiatedGenericParameter(source, i) ? undefined : getSingleCallSignature(getNonNullableType(sourceType)); + const targetSig = checkMode & SignatureCheckMode.Callback || isInstantiatedGenericParameter(target, i) ? undefined : getSingleCallSignature(getNonNullableType(targetType)); + const callbacks = sourceSig && targetSig && !getTypePredicateOfSignature(sourceSig) && !getTypePredicateOfSignature(targetSig) && + getTypeFacts(sourceType, TypeFacts.IsUndefinedOrNull) === getTypeFacts(targetType, TypeFacts.IsUndefinedOrNull); + let related = callbacks ? + compareSignaturesRelated(targetSig, sourceSig, (checkMode & SignatureCheckMode.StrictArity) | (strictVariance ? SignatureCheckMode.StrictCallback : SignatureCheckMode.BivariantCallback), reportErrors, errorReporter, incompatibleErrorReporter, compareTypes, reportUnreliableMarkers) : + !(checkMode & SignatureCheckMode.Callback) && !strictVariance && compareTypes(sourceType, targetType, /*reportErrors*/ false) || compareTypes(targetType, sourceType, reportErrors); + // With strict arity, (x: number | undefined) => void is a subtype of (x?: number | undefined) => void + if (related && checkMode & SignatureCheckMode.StrictArity && i >= getMinArgumentCount(source) && i < getMinArgumentCount(target) && compareTypes(sourceType, targetType, /*reportErrors*/ false)) { + related = Ternary.False; + } + if (!related) { + if (reportErrors) { + errorReporter!(Diagnostics.Types_of_parameters_0_and_1_are_incompatible, unescapeLeadingUnderscores(getParameterNameAtPosition(source, i)), unescapeLeadingUnderscores(getParameterNameAtPosition(target, i))); + } + return Ternary.False; + } + result &= related; + } + } + + if (!(checkMode & SignatureCheckMode.IgnoreReturnTypes)) { + // If a signature resolution is already in-flight, skip issuing a circularity error + // here and just use the `any` type directly + const targetReturnType = isResolvingReturnTypeOfSignature(target) ? anyType + : target.declaration && isJSConstructor(target.declaration) ? getDeclaredTypeOfClassOrInterface(getMergedSymbol(target.declaration.symbol)) + : getReturnTypeOfSignature(target); + if (targetReturnType === voidType || targetReturnType === anyType) { + return result; + } + const sourceReturnType = isResolvingReturnTypeOfSignature(source) ? anyType + : source.declaration && isJSConstructor(source.declaration) ? getDeclaredTypeOfClassOrInterface(getMergedSymbol(source.declaration.symbol)) + : getReturnTypeOfSignature(source); + + // The following block preserves behavior forbidding boolean returning functions from being assignable to type guard returning functions + const targetTypePredicate = getTypePredicateOfSignature(target); + if (targetTypePredicate) { + const sourceTypePredicate = getTypePredicateOfSignature(source); + if (sourceTypePredicate) { + result &= compareTypePredicateRelatedTo(sourceTypePredicate, targetTypePredicate, reportErrors, errorReporter, compareTypes); + } + else if (isIdentifierTypePredicate(targetTypePredicate) || isThisTypePredicate(targetTypePredicate)) { + if (reportErrors) { + errorReporter!(Diagnostics.Signature_0_must_be_a_type_predicate, signatureToString(source)); + } + return Ternary.False; + } + } + else { + // When relating callback signatures, we still need to relate return types bi-variantly as otherwise + // the containing type wouldn't be co-variant. For example, interface Foo { add(cb: () => T): void } + // wouldn't be co-variant for T without this rule. + result &= checkMode & SignatureCheckMode.BivariantCallback && compareTypes(targetReturnType, sourceReturnType, /*reportErrors*/ false) || + compareTypes(sourceReturnType, targetReturnType, reportErrors); + if (!result && reportErrors && incompatibleErrorReporter) { + incompatibleErrorReporter(sourceReturnType, targetReturnType); + } + } + } + + return result; + } + + function compareTypePredicateRelatedTo( + source: TypePredicate, + target: TypePredicate, + reportErrors: boolean, + errorReporter: ErrorReporter | undefined, + compareTypes: (s: Type, t: Type, reportErrors?: boolean) => Ternary, + ): Ternary { + if (source.kind !== target.kind) { + if (reportErrors) { + errorReporter!(Diagnostics.A_this_based_type_guard_is_not_compatible_with_a_parameter_based_type_guard); + errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); + } + return Ternary.False; + } + + if (source.kind === TypePredicateKind.Identifier || source.kind === TypePredicateKind.AssertsIdentifier) { + if (source.parameterIndex !== (target as IdentifierTypePredicate).parameterIndex) { + if (reportErrors) { + errorReporter!(Diagnostics.Parameter_0_is_not_in_the_same_position_as_parameter_1, source.parameterName, (target as IdentifierTypePredicate).parameterName); + errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); + } + return Ternary.False; + } + } + + const related = source.type === target.type ? Ternary.True : + source.type && target.type ? compareTypes(source.type, target.type, reportErrors) : + Ternary.False; + if (related === Ternary.False && reportErrors) { + errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); + } + return related; + } + + function isImplementationCompatibleWithOverload(implementation: Signature, overload: Signature): boolean { + const erasedSource = getErasedSignature(implementation); + const erasedTarget = getErasedSignature(overload); + + // First see if the return types are compatible in either direction. + const sourceReturnType = getReturnTypeOfSignature(erasedSource); + const targetReturnType = getReturnTypeOfSignature(erasedTarget); + if ( + targetReturnType === voidType + || isTypeRelatedTo(targetReturnType, sourceReturnType, assignableRelation) + || isTypeRelatedTo(sourceReturnType, targetReturnType, assignableRelation) + ) { + return isSignatureAssignableTo(erasedSource, erasedTarget, /*ignoreReturnTypes*/ true); + } + + return false; + } + + function isEmptyResolvedType(t: ResolvedType) { + return t !== anyFunctionType && + t.properties.length === 0 && + t.callSignatures.length === 0 && + t.constructSignatures.length === 0 && + t.indexInfos.length === 0; + } + + function isEmptyObjectType(type: Type): boolean { + return type.flags & TypeFlags.Object ? !isGenericMappedType(type) && isEmptyResolvedType(resolveStructuredTypeMembers(type as ObjectType)) : + type.flags & TypeFlags.NonPrimitive ? true : + type.flags & TypeFlags.Union ? some((type as UnionType).types, isEmptyObjectType) : + type.flags & TypeFlags.Intersection ? every((type as UnionType).types, isEmptyObjectType) : + false; + } + + function isEmptyAnonymousObjectType(type: Type) { + return !!(getObjectFlags(type) & ObjectFlags.Anonymous && ( + (type as ResolvedType).members && isEmptyResolvedType(type as ResolvedType) || + type.symbol && type.symbol.flags & SymbolFlags.TypeLiteral && getMembersOfSymbol(type.symbol).size === 0 + )); + } + + function isUnknownLikeUnionType(type: Type) { + if (strictNullChecks && type.flags & TypeFlags.Union) { + if (!((type as UnionType).objectFlags & ObjectFlags.IsUnknownLikeUnionComputed)) { + const types = (type as UnionType).types; + (type as UnionType).objectFlags |= ObjectFlags.IsUnknownLikeUnionComputed | (types.length >= 3 && types[0].flags & TypeFlags.Undefined && + types[1].flags & TypeFlags.Null && some(types, isEmptyAnonymousObjectType) ? ObjectFlags.IsUnknownLikeUnion : 0); + } + return !!((type as UnionType).objectFlags & ObjectFlags.IsUnknownLikeUnion); + } + return false; + } + + function containsUndefinedType(type: Type) { + return !!((type.flags & TypeFlags.Union ? (type as UnionType).types[0] : type).flags & TypeFlags.Undefined); + } + + function isStringIndexSignatureOnlyType(type: Type): boolean { + return type.flags & TypeFlags.Object && !isGenericMappedType(type) && getPropertiesOfType(type).length === 0 && getIndexInfosOfType(type).length === 1 && !!getIndexInfoOfType(type, stringType) || + type.flags & TypeFlags.UnionOrIntersection && every((type as UnionOrIntersectionType).types, isStringIndexSignatureOnlyType) || + false; + } + + function isEnumTypeRelatedTo(source: Symbol, target: Symbol, errorReporter?: ErrorReporter) { + const sourceSymbol = source.flags & SymbolFlags.EnumMember ? getParentOfSymbol(source)! : source; + const targetSymbol = target.flags & SymbolFlags.EnumMember ? getParentOfSymbol(target)! : target; + if (sourceSymbol === targetSymbol) { + return true; + } + if (sourceSymbol.escapedName !== targetSymbol.escapedName || !(sourceSymbol.flags & SymbolFlags.RegularEnum) || !(targetSymbol.flags & SymbolFlags.RegularEnum)) { + return false; + } + const id = getSymbolId(sourceSymbol) + "," + getSymbolId(targetSymbol); + const entry = enumRelation.get(id); + if (entry !== undefined && !(!(entry & RelationComparisonResult.Reported) && entry & RelationComparisonResult.Failed && errorReporter)) { + return !!(entry & RelationComparisonResult.Succeeded); + } + const targetEnumType = getTypeOfSymbol(targetSymbol); + for (const sourceProperty of getPropertiesOfType(getTypeOfSymbol(sourceSymbol))) { + if (sourceProperty.flags & SymbolFlags.EnumMember) { + const targetProperty = getPropertyOfType(targetEnumType, sourceProperty.escapedName); + if (!targetProperty || !(targetProperty.flags & SymbolFlags.EnumMember)) { + if (errorReporter) { + errorReporter(Diagnostics.Property_0_is_missing_in_type_1, symbolName(sourceProperty), typeToString(getDeclaredTypeOfSymbol(targetSymbol), /*enclosingDeclaration*/ undefined, TypeFormatFlags.UseFullyQualifiedType)); + enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); + } + else { + enumRelation.set(id, RelationComparisonResult.Failed); + } + return false; + } + const sourceValue = getEnumMemberValue(getDeclarationOfKind(sourceProperty, SyntaxKind.EnumMember)!).value; + const targetValue = getEnumMemberValue(getDeclarationOfKind(targetProperty, SyntaxKind.EnumMember)!).value; + if (sourceValue !== targetValue) { + const sourceIsString = typeof sourceValue === "string"; + const targetIsString = typeof targetValue === "string"; + + // If we have 2 enums with *known* values that differ, they are incompatible. + if (sourceValue !== undefined && targetValue !== undefined) { + if (!errorReporter) { + enumRelation.set(id, RelationComparisonResult.Failed); + } + else { + const escapedSource = sourceIsString ? `"${escapeString(sourceValue)}"` : sourceValue; + const escapedTarget = targetIsString ? `"${escapeString(targetValue)}"` : targetValue; + errorReporter(Diagnostics.Each_declaration_of_0_1_differs_in_its_value_where_2_was_expected_but_3_was_given, symbolName(targetSymbol), symbolName(targetProperty), escapedTarget, escapedSource); + enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); + } + return false; + } + + // At this point we know that at least one of the values is 'undefined'. + // This may mean that we have an opaque member from an ambient enum declaration, + // or that we were not able to calculate it (which is basically an error). + // + // Either way, we can assume that it's numeric. + // If the other is a string, we have a mismatch in types. + if (sourceIsString || targetIsString) { + if (!errorReporter) { + enumRelation.set(id, RelationComparisonResult.Failed); + } + else { + const knownStringValue = sourceValue ?? targetValue; + Debug.assert(typeof knownStringValue === "string"); + const escapedValue = `"${escapeString(knownStringValue)}"`; + errorReporter(Diagnostics.One_value_of_0_1_is_the_string_2_and_the_other_is_assumed_to_be_an_unknown_numeric_value, symbolName(targetSymbol), symbolName(targetProperty), escapedValue); + enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); + } + return false; + } + } + } + } + enumRelation.set(id, RelationComparisonResult.Succeeded); + return true; + } + + function isSimpleTypeRelatedTo(source: Type, target: Type, relation: Map, errorReporter?: ErrorReporter) { + const s = source.flags; + const t = target.flags; + if (t & TypeFlags.Any || s & TypeFlags.Never || source === wildcardType) return true; + if (t & TypeFlags.Unknown && !(relation === strictSubtypeRelation && s & TypeFlags.Any)) return true; + if (t & TypeFlags.Never) return false; + if (s & TypeFlags.StringLike && t & TypeFlags.String) return true; + if ( + s & TypeFlags.StringLiteral && s & TypeFlags.EnumLiteral && + t & TypeFlags.StringLiteral && !(t & TypeFlags.EnumLiteral) && + (source as StringLiteralType).value === (target as StringLiteralType).value + ) return true; + if (s & TypeFlags.NumberLike && t & TypeFlags.Number) return true; + if ( + s & TypeFlags.NumberLiteral && s & TypeFlags.EnumLiteral && + t & TypeFlags.NumberLiteral && !(t & TypeFlags.EnumLiteral) && + (source as NumberLiteralType).value === (target as NumberLiteralType).value + ) return true; + if (s & TypeFlags.BigIntLike && t & TypeFlags.BigInt) return true; + if (s & TypeFlags.BooleanLike && t & TypeFlags.Boolean) return true; + if (s & TypeFlags.ESSymbolLike && t & TypeFlags.ESSymbol) return true; + if ( + s & TypeFlags.Enum && t & TypeFlags.Enum && source.symbol.escapedName === target.symbol.escapedName && + isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter) + ) return true; + if (s & TypeFlags.EnumLiteral && t & TypeFlags.EnumLiteral) { + if (s & TypeFlags.Union && t & TypeFlags.Union && isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter)) return true; + if ( + s & TypeFlags.Literal && t & TypeFlags.Literal && (source as LiteralType).value === (target as LiteralType).value && + isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter) + ) return true; + } + // In non-strictNullChecks mode, `undefined` and `null` are assignable to anything except `never`. + // Since unions and intersections may reduce to `never`, we exclude them here. + if (s & TypeFlags.Undefined && (!strictNullChecks && !(t & TypeFlags.UnionOrIntersection) || t & (TypeFlags.Undefined | TypeFlags.Void))) return true; + if (s & TypeFlags.Null && (!strictNullChecks && !(t & TypeFlags.UnionOrIntersection) || t & TypeFlags.Null)) return true; + if (s & TypeFlags.Object && t & TypeFlags.NonPrimitive && !(relation === strictSubtypeRelation && isEmptyAnonymousObjectType(source) && !(getObjectFlags(source) & ObjectFlags.FreshLiteral))) return true; + if (relation === assignableRelation || relation === comparableRelation) { + if (s & TypeFlags.Any) return true; + // Type number is assignable to any computed numeric enum type or any numeric enum literal type, and + // a numeric literal type is assignable any computed numeric enum type or any numeric enum literal type + // with a matching value. These rules exist such that enums can be used for bit-flag purposes. + if (s & TypeFlags.Number && (t & TypeFlags.Enum || t & TypeFlags.NumberLiteral && t & TypeFlags.EnumLiteral)) return true; + if ( + s & TypeFlags.NumberLiteral && !(s & TypeFlags.EnumLiteral) && (t & TypeFlags.Enum || + t & TypeFlags.NumberLiteral && t & TypeFlags.EnumLiteral && + (source as NumberLiteralType).value === (target as NumberLiteralType).value) + ) return true; + // Anything is assignable to a union containing undefined, null, and {} + if (isUnknownLikeUnionType(target)) return true; + } + return false; + } + + function isTypeRelatedTo(source: Type, target: Type, relation: Map) { + if (isFreshLiteralType(source)) { + source = (source as FreshableType).regularType; + } + if (isFreshLiteralType(target)) { + target = (target as FreshableType).regularType; + } + if (source === target) { + return true; + } + if (relation !== identityRelation) { + if (relation === comparableRelation && !(target.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(target, source, relation) || isSimpleTypeRelatedTo(source, target, relation)) { + return true; + } + } + else if (!((source.flags | target.flags) & (TypeFlags.UnionOrIntersection | TypeFlags.IndexedAccess | TypeFlags.Conditional | TypeFlags.Substitution))) { + // We have excluded types that may simplify to other forms, so types must have identical flags + if (source.flags !== target.flags) return false; + if (source.flags & TypeFlags.Singleton) return true; + } + if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) { + const related = relation.get(getRelationKey(source, target, IntersectionState.None, relation, /*ignoreConstraints*/ false)); + if (related !== undefined) { + return !!(related & RelationComparisonResult.Succeeded); + } + } + if (source.flags & TypeFlags.StructuredOrInstantiable || target.flags & TypeFlags.StructuredOrInstantiable) { + return checkTypeRelatedTo(source, target, relation, /*errorNode*/ undefined); + } + return false; + } + + function isIgnoredJsxProperty(source: Type, sourceProp: Symbol) { + return getObjectFlags(source) & ObjectFlags.JsxAttributes && isHyphenatedJsxName(sourceProp.escapedName); + } + + function getNormalizedType(type: Type, writing: boolean): Type { + while (true) { + const t = isFreshLiteralType(type) ? (type as FreshableType).regularType : + isGenericTupleType(type) ? getNormalizedTupleType(type, writing) : + getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).node ? createTypeReference((type as TypeReference).target, getTypeArguments(type as TypeReference)) : getSingleBaseForNonAugmentingSubtype(type) || type : + type.flags & TypeFlags.UnionOrIntersection ? getNormalizedUnionOrIntersectionType(type as UnionOrIntersectionType, writing) : + type.flags & TypeFlags.Substitution ? writing ? (type as SubstitutionType).baseType : getSubstitutionIntersection(type as SubstitutionType) : + type.flags & TypeFlags.Simplifiable ? getSimplifiedType(type, writing) : + type; + if (t === type) return t; + type = t; + } + } + + function getNormalizedUnionOrIntersectionType(type: UnionOrIntersectionType, writing: boolean) { + const reduced = getReducedType(type); + if (reduced !== type) { + return reduced; + } + if (type.flags & TypeFlags.Intersection && shouldNormalizeIntersection(type as IntersectionType)) { + // Normalization handles cases like + // Partial[K] & ({} | null) ==> + // Partial[K] & {} | Partial[K} & null ==> + // (T[K] | undefined) & {} | (T[K] | undefined) & null ==> + // T[K] & {} | undefined & {} | T[K] & null | undefined & null ==> + // T[K] & {} | T[K] & null + const normalizedTypes = sameMap(type.types, t => getNormalizedType(t, writing)); + if (normalizedTypes !== type.types) { + return getIntersectionType(normalizedTypes); + } + } + return type; + } + + function shouldNormalizeIntersection(type: IntersectionType) { + let hasInstantiable = false; + let hasNullableOrEmpty = false; + for (const t of type.types) { + hasInstantiable ||= !!(t.flags & TypeFlags.Instantiable); + hasNullableOrEmpty ||= !!(t.flags & TypeFlags.Nullable) || isEmptyAnonymousObjectType(t); + if (hasInstantiable && hasNullableOrEmpty) return true; + } + return false; + } + + function getNormalizedTupleType(type: TupleTypeReference, writing: boolean): Type { + const elements = getElementTypes(type); + const normalizedElements = sameMap(elements, t => t.flags & TypeFlags.Simplifiable ? getSimplifiedType(t, writing) : t); + return elements !== normalizedElements ? createNormalizedTupleType(type.target, normalizedElements) : type; + } + + /** + * Checks if 'source' is related to 'target' (e.g.: is a assignable to). + * @param source The left-hand-side of the relation. + * @param target The right-hand-side of the relation. + * @param relation The relation considered. One of 'identityRelation', 'subtypeRelation', 'assignableRelation', or 'comparableRelation'. + * Used as both to determine which checks are performed and as a cache of previously computed results. + * @param errorNode The suggested node upon which all errors will be reported, if defined. This may or may not be the actual node used. + * @param headMessage If the error chain should be prepended by a head message, then headMessage will be used. + * @param containingMessageChain A chain of errors to prepend any new errors found. + * @param errorOutputContainer Return the diagnostic. Do not log if 'skipLogging' is truthy. + */ + function checkTypeRelatedTo( + source: Type, + target: Type, + relation: Map, + errorNode: Node | undefined, + headMessage?: DiagnosticMessage, + containingMessageChain?: () => DiagnosticMessageChain | undefined, + errorOutputContainer?: { errors?: Diagnostic[]; skipLogging?: boolean; }, + ): boolean { + let errorInfo: DiagnosticMessageChain | undefined; + let relatedInfo: [DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined; + let maybeKeys: string[]; + let maybeKeysSet: Set; + let sourceStack: Type[]; + let targetStack: Type[]; + let maybeCount = 0; + let sourceDepth = 0; + let targetDepth = 0; + let expandingFlags = ExpandingFlags.None; + let overflow = false; + let overrideNextErrorInfo = 0; // How many `reportRelationError` calls should be skipped in the elaboration pyramid + let skipParentCounter = 0; // How many errors should be skipped 'above' in the elaboration pyramid + let lastSkippedInfo: [Type, Type] | undefined; + let incompatibleStack: DiagnosticAndArguments[] | undefined; + // In Node.js, the maximum number of elements in a map is 2^24. We limit the number of entries an invocation + // of checkTypeRelatedTo can add to a relation to 1/8th of its remaining capacity. + let relationCount = (16_000_000 - relation.size) >> 3; + + Debug.assert(relation !== identityRelation || !errorNode, "no error reporting in identity checking"); + + const result = isRelatedTo(source, target, RecursionFlags.Both, /*reportErrors*/ !!errorNode, headMessage); + if (incompatibleStack) { + reportIncompatibleStack(); + } + if (overflow) { + // Record this relation as having failed such that we don't attempt the overflowing operation again. + const id = getRelationKey(source, target, /*intersectionState*/ IntersectionState.None, relation, /*ignoreConstraints*/ false); + relation.set(id, RelationComparisonResult.Reported | RelationComparisonResult.Failed); + tracing?.instant(tracing.Phase.CheckTypes, "checkTypeRelatedTo_DepthLimit", { sourceId: source.id, targetId: target.id, depth: sourceDepth, targetDepth }); + const message = relationCount <= 0 ? + Diagnostics.Excessive_complexity_comparing_types_0_and_1 : + Diagnostics.Excessive_stack_depth_comparing_types_0_and_1; + const diag = error(errorNode || currentNode, message, typeToString(source), typeToString(target)); + if (errorOutputContainer) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + } + else if (errorInfo) { + if (containingMessageChain) { + const chain = containingMessageChain(); + if (chain) { + concatenateDiagnosticMessageChains(chain, errorInfo); + errorInfo = chain; + } + } + + let relatedInformation: DiagnosticRelatedInformation[] | undefined; + // Check if we should issue an extra diagnostic to produce a quickfix for a slightly incorrect import statement + if (headMessage && errorNode && !result && source.symbol) { + const links = getSymbolLinks(source.symbol); + if (links.originatingImport && !isImportCall(links.originatingImport)) { + const helpfulRetry = checkTypeRelatedTo(getTypeOfSymbol(links.target!), target, relation, /*errorNode*/ undefined); + if (helpfulRetry) { + // Likely an incorrect import. Issue a helpful diagnostic to produce a quickfix to change the import + const diag = createDiagnosticForNode(links.originatingImport, Diagnostics.Type_originates_at_this_import_A_namespace_style_import_cannot_be_called_or_constructed_and_will_cause_a_failure_at_runtime_Consider_using_a_default_import_or_import_require_here_instead); + relatedInformation = append(relatedInformation, diag); // Cause the error to appear with the error that triggered it + } + } + } + const diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorNode!), errorNode!, errorInfo, relatedInformation); + if (relatedInfo) { + addRelatedInfo(diag, ...relatedInfo); + } + if (errorOutputContainer) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + if (!errorOutputContainer || !errorOutputContainer.skipLogging) { + diagnostics.add(diag); + } + } + if (errorNode && errorOutputContainer && errorOutputContainer.skipLogging && result === Ternary.False) { + Debug.assert(!!errorOutputContainer.errors, "missed opportunity to interact with error."); + } + + return result !== Ternary.False; + + function resetErrorInfo(saved: ReturnType) { + errorInfo = saved.errorInfo; + lastSkippedInfo = saved.lastSkippedInfo; + incompatibleStack = saved.incompatibleStack; + overrideNextErrorInfo = saved.overrideNextErrorInfo; + skipParentCounter = saved.skipParentCounter; + relatedInfo = saved.relatedInfo; + } + + function captureErrorCalculationState() { + return { + errorInfo, + lastSkippedInfo, + incompatibleStack: incompatibleStack?.slice(), + overrideNextErrorInfo, + skipParentCounter, + relatedInfo: relatedInfo?.slice() as [DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined, + }; + } + + function reportIncompatibleError(message: DiagnosticMessage, ...args: DiagnosticArguments) { + overrideNextErrorInfo++; // Suppress the next relation error + lastSkippedInfo = undefined; // Reset skipped info cache + (incompatibleStack ||= []).push([message, ...args]); + } + + function reportIncompatibleStack() { + const stack = incompatibleStack || []; + incompatibleStack = undefined; + const info = lastSkippedInfo; + lastSkippedInfo = undefined; + if (stack.length === 1) { + reportError(...stack[0]); + if (info) { + // Actually do the last relation error + reportRelationError(/*message*/ undefined, ...info); + } + return; + } + // The first error will be the innermost, while the last will be the outermost - so by popping off the end, + // we can build from left to right + let path = ""; + const secondaryRootErrors: DiagnosticAndArguments[] = []; + while (stack.length) { + const [msg, ...args] = stack.pop()!; + switch (msg.code) { + case Diagnostics.Types_of_property_0_are_incompatible.code: { + // Parenthesize a `new` if there is one + if (path.indexOf("new ") === 0) { + path = `(${path})`; + } + const str = "" + args[0]; + // If leading, just print back the arg (irrespective of if it's a valid identifier) + if (path.length === 0) { + path = `${str}`; + } + // Otherwise write a dotted name if possible + else if (isIdentifierText(str, getEmitScriptTarget(compilerOptions))) { + path = `${path}.${str}`; + } + // Failing that, check if the name is already a computed name + else if (str[0] === "[" && str[str.length - 1] === "]") { + path = `${path}${str}`; + } + // And finally write out a computed name as a last resort + else { + path = `${path}[${str}]`; + } + break; + } + case Diagnostics.Call_signature_return_types_0_and_1_are_incompatible.code: + case Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code: + case Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code: + case Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code: { + if (path.length === 0) { + // Don't flatten signature compatability errors at the start of a chain - instead prefer + // to unify (the with no arguments bit is excessive for printback) and print them back + let mappedMsg = msg; + if (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) { + mappedMsg = Diagnostics.Call_signature_return_types_0_and_1_are_incompatible; + } + else if (msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) { + mappedMsg = Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible; + } + secondaryRootErrors.unshift([mappedMsg, args[0], args[1]]); + } + else { + const prefix = (msg.code === Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code || + msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) + ? "new " + : ""; + const params = (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code || + msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) + ? "" + : "..."; + path = `${prefix}${path}(${params})`; + } + break; + } + case Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target.code: { + secondaryRootErrors.unshift([Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target, args[0], args[1]]); + break; + } + case Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target.code: { + secondaryRootErrors.unshift([Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target, args[0], args[1], args[2]]); + break; + } + default: + return Debug.fail(`Unhandled Diagnostic: ${msg.code}`); + } + } + if (path) { + reportError( + path[path.length - 1] === ")" + ? Diagnostics.The_types_returned_by_0_are_incompatible_between_these_types + : Diagnostics.The_types_of_0_are_incompatible_between_these_types, + path, + ); + } + else { + // Remove the innermost secondary error as it will duplicate the error already reported by `reportRelationError` on entry + secondaryRootErrors.shift(); + } + for (const [msg, ...args] of secondaryRootErrors) { + const originalValue = msg.elidedInCompatabilityPyramid; + msg.elidedInCompatabilityPyramid = false; // Temporarily override elision to ensure error is reported + reportError(msg, ...args); + msg.elidedInCompatabilityPyramid = originalValue; + } + if (info) { + // Actually do the last relation error + reportRelationError(/*message*/ undefined, ...info); + } + } + + function reportError(message: DiagnosticMessage, ...args: DiagnosticArguments): void { + Debug.assert(!!errorNode); + if (incompatibleStack) reportIncompatibleStack(); + if (message.elidedInCompatabilityPyramid) return; + if (skipParentCounter === 0) { + errorInfo = chainDiagnosticMessages(errorInfo, message, ...args); + } + else { + skipParentCounter--; + } + } + + function reportParentSkippedError(message: DiagnosticMessage, ...args: DiagnosticArguments): void { + reportError(message, ...args); + skipParentCounter++; + } + + function associateRelatedInfo(info: DiagnosticRelatedInformation) { + Debug.assert(!!errorInfo); + if (!relatedInfo) { + relatedInfo = [info]; + } + else { + relatedInfo.push(info); + } + } + + function reportRelationError(message: DiagnosticMessage | undefined, source: Type, target: Type) { + if (incompatibleStack) reportIncompatibleStack(); + const [sourceType, targetType] = getTypeNamesForErrorDisplay(source, target); + let generalizedSource = source; + let generalizedSourceType = sourceType; + + if (isLiteralType(source) && !typeCouldHaveTopLevelSingletonTypes(target)) { + generalizedSource = getBaseTypeOfLiteralType(source); + Debug.assert(!isTypeAssignableTo(generalizedSource, target), "generalized source shouldn't be assignable"); + generalizedSourceType = getTypeNameForErrorDisplay(generalizedSource); + } + + // If `target` is of indexed access type (And `source` it is not), we use the object type of `target` for better error reporting + const targetFlags = target.flags & TypeFlags.IndexedAccess && !(source.flags & TypeFlags.IndexedAccess) ? + (target as IndexedAccessType).objectType.flags : + target.flags; + + if (targetFlags & TypeFlags.TypeParameter && target !== markerSuperTypeForCheck && target !== markerSubTypeForCheck) { + const constraint = getBaseConstraintOfType(target); + let needsOriginalSource; + if (constraint && (isTypeAssignableTo(generalizedSource, constraint) || (needsOriginalSource = isTypeAssignableTo(source, constraint)))) { + reportError( + Diagnostics._0_is_assignable_to_the_constraint_of_type_1_but_1_could_be_instantiated_with_a_different_subtype_of_constraint_2, + needsOriginalSource ? sourceType : generalizedSourceType, + targetType, + typeToString(constraint), + ); + } + else { + errorInfo = undefined; + reportError( + Diagnostics._0_could_be_instantiated_with_an_arbitrary_type_which_could_be_unrelated_to_1, + targetType, + generalizedSourceType, + ); + } + } + + if (!message) { + if (relation === comparableRelation) { + message = Diagnostics.Type_0_is_not_comparable_to_type_1; + } + else if (sourceType === targetType) { + message = Diagnostics.Type_0_is_not_assignable_to_type_1_Two_different_types_with_this_name_exist_but_they_are_unrelated; + } + else if (exactOptionalPropertyTypes && getExactOptionalUnassignableProperties(source, target).length) { + message = Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties; + } + else { + if (source.flags & TypeFlags.StringLiteral && target.flags & TypeFlags.Union) { + const suggestedType = getSuggestedTypeForNonexistentStringLiteralType(source as StringLiteralType, target as UnionType); + if (suggestedType) { + reportError(Diagnostics.Type_0_is_not_assignable_to_type_1_Did_you_mean_2, generalizedSourceType, targetType, typeToString(suggestedType)); + return; + } + } + message = Diagnostics.Type_0_is_not_assignable_to_type_1; + } + } + else if ( + message === Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1 + && exactOptionalPropertyTypes + && getExactOptionalUnassignableProperties(source, target).length + ) { + message = Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties; + } + + reportError(message, generalizedSourceType, targetType); + } + + function tryElaborateErrorsForPrimitivesAndObjects(source: Type, target: Type) { + const sourceType = symbolValueDeclarationIsContextSensitive(source.symbol) ? typeToString(source, source.symbol.valueDeclaration) : typeToString(source); + const targetType = symbolValueDeclarationIsContextSensitive(target.symbol) ? typeToString(target, target.symbol.valueDeclaration) : typeToString(target); + + if ( + (globalStringType === source && stringType === target) || + (globalNumberType === source && numberType === target) || + (globalBooleanType === source && booleanType === target) || + (getGlobalESSymbolType() === source && esSymbolType === target) + ) { + reportError(Diagnostics._0_is_a_primitive_but_1_is_a_wrapper_object_Prefer_using_0_when_possible, targetType, sourceType); + } + } + + /** + * Try and elaborate array and tuple errors. Returns false + * if we have found an elaboration, or we should ignore + * any other elaborations when relating the `source` and + * `target` types. + */ + function tryElaborateArrayLikeErrors(source: Type, target: Type, reportErrors: boolean): boolean { + /** + * The spec for elaboration is: + * - If the source is a readonly tuple and the target is a mutable array or tuple, elaborate on mutability and skip property elaborations. + * - If the source is a tuple then skip property elaborations if the target is an array or tuple. + * - If the source is a readonly array and the target is a mutable array or tuple, elaborate on mutability and skip property elaborations. + * - If the source an array then skip property elaborations if the target is a tuple. + */ + if (isTupleType(source)) { + if (source.target.readonly && isMutableArrayOrTuple(target)) { + if (reportErrors) { + reportError(Diagnostics.The_type_0_is_readonly_and_cannot_be_assigned_to_the_mutable_type_1, typeToString(source), typeToString(target)); + } + return false; + } + return isArrayOrTupleType(target); + } + if (isReadonlyArrayType(source) && isMutableArrayOrTuple(target)) { + if (reportErrors) { + reportError(Diagnostics.The_type_0_is_readonly_and_cannot_be_assigned_to_the_mutable_type_1, typeToString(source), typeToString(target)); + } + return false; + } + if (isTupleType(target)) { + return isArrayType(source); + } + return true; + } + + function isRelatedToWorker(source: Type, target: Type, reportErrors?: boolean) { + return isRelatedTo(source, target, RecursionFlags.Both, reportErrors); + } + + /** + * Compare two types and return + * * Ternary.True if they are related with no assumptions, + * * Ternary.Maybe if they are related with assumptions of other relationships, or + * * Ternary.False if they are not related. + */ + function isRelatedTo(originalSource: Type, originalTarget: Type, recursionFlags: RecursionFlags = RecursionFlags.Both, reportErrors = false, headMessage?: DiagnosticMessage, intersectionState = IntersectionState.None): Ternary { + if (originalSource === originalTarget) return Ternary.True; + + // Before normalization: if `source` is type an object type, and `target` is primitive, + // skip all the checks we don't need and just return `isSimpleTypeRelatedTo` result + if (originalSource.flags & TypeFlags.Object && originalTarget.flags & TypeFlags.Primitive) { + if ( + relation === comparableRelation && !(originalTarget.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(originalTarget, originalSource, relation) || + isSimpleTypeRelatedTo(originalSource, originalTarget, relation, reportErrors ? reportError : undefined) + ) { + return Ternary.True; + } + if (reportErrors) { + reportErrorResults(originalSource, originalTarget, originalSource, originalTarget, headMessage); + } + return Ternary.False; + } + + // Normalize the source and target types: Turn fresh literal types into regular literal types, + // turn deferred type references into regular type references, simplify indexed access and + // conditional types, and resolve substitution types to either the substitution (on the source + // side) or the type variable (on the target side). + const source = getNormalizedType(originalSource, /*writing*/ false); + let target = getNormalizedType(originalTarget, /*writing*/ true); + + if (source === target) return Ternary.True; + + if (relation === identityRelation) { + if (source.flags !== target.flags) return Ternary.False; + if (source.flags & TypeFlags.Singleton) return Ternary.True; + traceUnionsOrIntersectionsTooLarge(source, target); + return recursiveTypeRelatedTo(source, target, /*reportErrors*/ false, IntersectionState.None, recursionFlags); + } + + // We fastpath comparing a type parameter to exactly its constraint, as this is _super_ common, + // and otherwise, for type parameters in large unions, causes us to need to compare the union to itself, + // as we break down the _target_ union first, _then_ get the source constraint - so for every + // member of the target, we attempt to find a match in the source. This avoids that in cases where + // the target is exactly the constraint. + if (source.flags & TypeFlags.TypeParameter && getConstraintOfType(source) === target) { + return Ternary.True; + } + + // See if we're relating a definitely non-nullable type to a union that includes null and/or undefined + // plus a single non-nullable type. If so, remove null and/or undefined from the target type. + if (source.flags & TypeFlags.DefinitelyNonNullable && target.flags & TypeFlags.Union) { + const types = (target as UnionType).types; + const candidate = types.length === 2 && types[0].flags & TypeFlags.Nullable ? types[1] : + types.length === 3 && types[0].flags & TypeFlags.Nullable && types[1].flags & TypeFlags.Nullable ? types[2] : + undefined; + if (candidate && !(candidate.flags & TypeFlags.Nullable)) { + target = getNormalizedType(candidate, /*writing*/ true); + if (source === target) return Ternary.True; + } + } + + if ( + relation === comparableRelation && !(target.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(target, source, relation) || + isSimpleTypeRelatedTo(source, target, relation, reportErrors ? reportError : undefined) + ) return Ternary.True; + + if (source.flags & TypeFlags.StructuredOrInstantiable || target.flags & TypeFlags.StructuredOrInstantiable) { + const isPerformingExcessPropertyChecks = !(intersectionState & IntersectionState.Target) && (isObjectLiteralType(source) && getObjectFlags(source) & ObjectFlags.FreshLiteral); + if (isPerformingExcessPropertyChecks) { + if (hasExcessProperties(source as FreshObjectLiteralType, target, reportErrors)) { + if (reportErrors) { + reportRelationError(headMessage, source, originalTarget.aliasSymbol ? originalTarget : target); + } + return Ternary.False; + } + } + + const isPerformingCommonPropertyChecks = (relation !== comparableRelation || isUnitType(source)) && + !(intersectionState & IntersectionState.Target) && + source.flags & (TypeFlags.Primitive | TypeFlags.Object | TypeFlags.Intersection) && source !== globalObjectType && + target.flags & (TypeFlags.Object | TypeFlags.Intersection) && isWeakType(target) && + (getPropertiesOfType(source).length > 0 || typeHasCallOrConstructSignatures(source)); + const isComparingJsxAttributes = !!(getObjectFlags(source) & ObjectFlags.JsxAttributes); + if (isPerformingCommonPropertyChecks && !hasCommonProperties(source, target, isComparingJsxAttributes)) { + if (reportErrors) { + const sourceString = typeToString(originalSource.aliasSymbol ? originalSource : source); + const targetString = typeToString(originalTarget.aliasSymbol ? originalTarget : target); + const calls = getSignaturesOfType(source, SignatureKind.Call); + const constructs = getSignaturesOfType(source, SignatureKind.Construct); + if ( + calls.length > 0 && isRelatedTo(getReturnTypeOfSignature(calls[0]), target, RecursionFlags.Source, /*reportErrors*/ false) || + constructs.length > 0 && isRelatedTo(getReturnTypeOfSignature(constructs[0]), target, RecursionFlags.Source, /*reportErrors*/ false) + ) { + reportError(Diagnostics.Value_of_type_0_has_no_properties_in_common_with_type_1_Did_you_mean_to_call_it, sourceString, targetString); + } + else { + reportError(Diagnostics.Type_0_has_no_properties_in_common_with_type_1, sourceString, targetString); + } + } + return Ternary.False; + } + + traceUnionsOrIntersectionsTooLarge(source, target); + + const skipCaching = source.flags & TypeFlags.Union && (source as UnionType).types.length < 4 && !(target.flags & TypeFlags.Union) || + target.flags & TypeFlags.Union && (target as UnionType).types.length < 4 && !(source.flags & TypeFlags.StructuredOrInstantiable); + const result = skipCaching ? + unionOrIntersectionRelatedTo(source, target, reportErrors, intersectionState) : + recursiveTypeRelatedTo(source, target, reportErrors, intersectionState, recursionFlags); + if (result) { + return result; + } + } + + if (reportErrors) { + reportErrorResults(originalSource, originalTarget, source, target, headMessage); + } + return Ternary.False; + } + + function reportErrorResults(originalSource: Type, originalTarget: Type, source: Type, target: Type, headMessage: DiagnosticMessage | undefined) { + const sourceHasBase = !!getSingleBaseForNonAugmentingSubtype(originalSource); + const targetHasBase = !!getSingleBaseForNonAugmentingSubtype(originalTarget); + source = (originalSource.aliasSymbol || sourceHasBase) ? originalSource : source; + target = (originalTarget.aliasSymbol || targetHasBase) ? originalTarget : target; + let maybeSuppress = overrideNextErrorInfo > 0; + if (maybeSuppress) { + overrideNextErrorInfo--; + } + if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) { + const currentError = errorInfo; + tryElaborateArrayLikeErrors(source, target, /*reportErrors*/ true); + if (errorInfo !== currentError) { + maybeSuppress = !!errorInfo; + } + } + if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Primitive) { + tryElaborateErrorsForPrimitivesAndObjects(source, target); + } + else if (source.symbol && source.flags & TypeFlags.Object && globalObjectType === source) { + reportError(Diagnostics.The_Object_type_is_assignable_to_very_few_other_types_Did_you_mean_to_use_the_any_type_instead); + } + else if (getObjectFlags(source) & ObjectFlags.JsxAttributes && target.flags & TypeFlags.Intersection) { + const targetTypes = (target as IntersectionType).types; + const intrinsicAttributes = getJsxType(JsxNames.IntrinsicAttributes, errorNode); + const intrinsicClassAttributes = getJsxType(JsxNames.IntrinsicClassAttributes, errorNode); + if ( + !isErrorType(intrinsicAttributes) && !isErrorType(intrinsicClassAttributes) && + (contains(targetTypes, intrinsicAttributes) || contains(targetTypes, intrinsicClassAttributes)) + ) { + // do not report top error + return; + } + } + else { + errorInfo = elaborateNeverIntersection(errorInfo, originalTarget); + } + // Used by, eg, missing property checking to replace the top-level message with a more informative one. + if (!headMessage && maybeSuppress) { + // We suppress a call to `reportRelationError` or not depending on the state of the type checker, so + // we call `reportRelationError` here and then undo its effects to figure out what would be the diagnostic + // if we hadn't supress it, and save that as a canonical diagnostic for deduplication purposes. + const savedErrorState = captureErrorCalculationState(); + reportRelationError(headMessage, source, target); + let canonical; + if (errorInfo && errorInfo !== savedErrorState.errorInfo) { + canonical = { code: errorInfo.code, messageText: errorInfo.messageText }; + } + resetErrorInfo(savedErrorState); + if (canonical && errorInfo) { + errorInfo.canonicalHead = canonical; + } + + lastSkippedInfo = [source, target]; + return; + } + reportRelationError(headMessage, source, target); + if (source.flags & TypeFlags.TypeParameter && source.symbol?.declarations?.[0] && !getConstraintOfType(source as TypeVariable)) { + const syntheticParam = cloneTypeParameter(source as TypeParameter); + syntheticParam.constraint = instantiateType(target, makeUnaryTypeMapper(source, syntheticParam)); + if (hasNonCircularBaseConstraint(syntheticParam)) { + const targetConstraintString = typeToString(target, source.symbol.declarations[0]); + associateRelatedInfo(createDiagnosticForNode(source.symbol.declarations[0], Diagnostics.This_type_parameter_might_need_an_extends_0_constraint, targetConstraintString)); + } + } + } + + function traceUnionsOrIntersectionsTooLarge(source: Type, target: Type): void { + if (!tracing) { + return; + } + + if ((source.flags & TypeFlags.UnionOrIntersection) && (target.flags & TypeFlags.UnionOrIntersection)) { + const sourceUnionOrIntersection = source as UnionOrIntersectionType; + const targetUnionOrIntersection = target as UnionOrIntersectionType; + + if (sourceUnionOrIntersection.objectFlags & targetUnionOrIntersection.objectFlags & ObjectFlags.PrimitiveUnion) { + // There's a fast path for comparing primitive unions + return; + } + + const sourceSize = sourceUnionOrIntersection.types.length; + const targetSize = targetUnionOrIntersection.types.length; + if (sourceSize * targetSize > 1E6) { + tracing.instant(tracing.Phase.CheckTypes, "traceUnionsOrIntersectionsTooLarge_DepthLimit", { + sourceId: source.id, + sourceSize, + targetId: target.id, + targetSize, + pos: errorNode?.pos, + end: errorNode?.end, + }); + } + } + } + + function getTypeOfPropertyInTypes(types: Type[], name: __String) { + const appendPropType = (propTypes: Type[] | undefined, type: Type) => { + type = getApparentType(type); + const prop = type.flags & TypeFlags.UnionOrIntersection ? getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name) : getPropertyOfObjectType(type, name); + const propType = prop && getTypeOfSymbol(prop) || getApplicableIndexInfoForName(type, name)?.type || undefinedType; + return append(propTypes, propType); + }; + return getUnionType(reduceLeft(types, appendPropType, /*initial*/ undefined) || emptyArray); + } + + function hasExcessProperties(source: FreshObjectLiteralType, target: Type, reportErrors: boolean): boolean { + if (!isExcessPropertyCheckTarget(target) || !noImplicitAny && getObjectFlags(target) & ObjectFlags.JSLiteral) { + return false; // Disable excess property checks on JS literals to simulate having an implicit "index signature" - but only outside of noImplicitAny + } + const isComparingJsxAttributes = !!(getObjectFlags(source) & ObjectFlags.JsxAttributes); + if ( + (relation === assignableRelation || relation === comparableRelation) && + (isTypeSubsetOf(globalObjectType, target) || (!isComparingJsxAttributes && isEmptyObjectType(target))) + ) { + return false; + } + let reducedTarget = target; + let checkTypes: Type[] | undefined; + if (target.flags & TypeFlags.Union) { + reducedTarget = findMatchingDiscriminantType(source, target as UnionType, isRelatedTo) || filterPrimitivesIfContainsNonPrimitive(target as UnionType); + checkTypes = reducedTarget.flags & TypeFlags.Union ? (reducedTarget as UnionType).types : [reducedTarget]; + } + for (const prop of getPropertiesOfType(source)) { + if (shouldCheckAsExcessProperty(prop, source.symbol) && !isIgnoredJsxProperty(source, prop)) { + if (!isKnownProperty(reducedTarget, prop.escapedName, isComparingJsxAttributes)) { + if (reportErrors) { + // Report error in terms of object types in the target as those are the only ones + // we check in isKnownProperty. + const errorTarget = filterType(reducedTarget, isExcessPropertyCheckTarget); + // We know *exactly* where things went wrong when comparing the types. + // Use this property as the error node as this will be more helpful in + // reasoning about what went wrong. + if (!errorNode) return Debug.fail(); + if (isJsxAttributes(errorNode) || isJsxOpeningLikeElement(errorNode) || isJsxOpeningLikeElement(errorNode.parent)) { + // JsxAttributes has an object-literal flag and undergo same type-assignablity check as normal object-literal. + // However, using an object-literal error message will be very confusing to the users so we give different a message. + if (prop.valueDeclaration && isJsxAttribute(prop.valueDeclaration) && getSourceFileOfNode(errorNode) === getSourceFileOfNode(prop.valueDeclaration.name)) { + // Note that extraneous children (as in `extra`) don't pass this check, + // since `children` is a SyntaxKind.PropertySignature instead of a SyntaxKind.JsxAttribute. + errorNode = prop.valueDeclaration.name; + } + const propName = symbolToString(prop); + const suggestionSymbol = getSuggestedSymbolForNonexistentJSXAttribute(propName, errorTarget); + const suggestion = suggestionSymbol ? symbolToString(suggestionSymbol) : undefined; + if (suggestion) { + reportError(Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2, propName, typeToString(errorTarget), suggestion); + } + else { + reportError(Diagnostics.Property_0_does_not_exist_on_type_1, propName, typeToString(errorTarget)); + } + } + else { + // use the property's value declaration if the property is assigned inside the literal itself + const objectLiteralDeclaration = source.symbol?.declarations && firstOrUndefined(source.symbol.declarations); + let suggestion: string | undefined; + if (prop.valueDeclaration && findAncestor(prop.valueDeclaration, d => d === objectLiteralDeclaration) && getSourceFileOfNode(objectLiteralDeclaration) === getSourceFileOfNode(errorNode)) { + const propDeclaration = prop.valueDeclaration as ObjectLiteralElementLike; + Debug.assertNode(propDeclaration, isObjectLiteralElementLike); + + const name = propDeclaration.name!; + errorNode = name; + + if (isIdentifier(name)) { + suggestion = getSuggestionForNonexistentProperty(name, errorTarget); + } + } + if (suggestion !== undefined) { + reportParentSkippedError(Diagnostics.Object_literal_may_only_specify_known_properties_but_0_does_not_exist_in_type_1_Did_you_mean_to_write_2, symbolToString(prop), typeToString(errorTarget), suggestion); + } + else { + reportParentSkippedError(Diagnostics.Object_literal_may_only_specify_known_properties_and_0_does_not_exist_in_type_1, symbolToString(prop), typeToString(errorTarget)); + } + } + } + return true; + } + if (checkTypes && !isRelatedTo(getTypeOfSymbol(prop), getTypeOfPropertyInTypes(checkTypes, prop.escapedName), RecursionFlags.Both, reportErrors)) { + if (reportErrors) { + reportIncompatibleError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(prop)); + } + return true; + } + } + } + return false; + } + + function shouldCheckAsExcessProperty(prop: Symbol, container: Symbol) { + return prop.valueDeclaration && container.valueDeclaration && prop.valueDeclaration.parent === container.valueDeclaration; + } + + function unionOrIntersectionRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + // Note that these checks are specifically ordered to produce correct results. In particular, + // we need to deconstruct unions before intersections (because unions are always at the top), + // and we need to handle "each" relations before "some" relations for the same kind of type. + if (source.flags & TypeFlags.Union) { + if (target.flags & TypeFlags.Union) { + // Intersections of union types are normalized into unions of intersection types, and such normalized + // unions can get very large and expensive to relate. The following fast path checks if the source union + // originated in an intersection. If so, and if that intersection contains the target type, then we know + // the result to be true (for any two types A and B, A & B is related to both A and B). + const sourceOrigin = (source as UnionType).origin; + if (sourceOrigin && sourceOrigin.flags & TypeFlags.Intersection && target.aliasSymbol && contains((sourceOrigin as IntersectionType).types, target)) { + return Ternary.True; + } + // Similarly, in unions of unions the we preserve the original list of unions. This original list is often + // much shorter than the normalized result, so we scan it in the following fast path. + const targetOrigin = (target as UnionType).origin; + if (targetOrigin && targetOrigin.flags & TypeFlags.Union && source.aliasSymbol && contains((targetOrigin as UnionType).types, source)) { + return Ternary.True; + } + } + return relation === comparableRelation ? + someTypeRelatedToType(source as UnionType, target, reportErrors && !(source.flags & TypeFlags.Primitive), intersectionState) : + eachTypeRelatedToType(source as UnionType, target, reportErrors && !(source.flags & TypeFlags.Primitive), intersectionState); + } + if (target.flags & TypeFlags.Union) { + return typeRelatedToSomeType(getRegularTypeOfObjectLiteral(source), target as UnionType, reportErrors && !(source.flags & TypeFlags.Primitive) && !(target.flags & TypeFlags.Primitive), intersectionState); + } + if (target.flags & TypeFlags.Intersection) { + return typeRelatedToEachType(source, target as IntersectionType, reportErrors, IntersectionState.Target); + } + // Source is an intersection. For the comparable relation, if the target is a primitive type we hoist the + // constraints of all non-primitive types in the source into a new intersection. We do this because the + // intersection may further constrain the constraints of the non-primitive types. For example, given a type + // parameter 'T extends 1 | 2', the intersection 'T & 1' should be reduced to '1' such that it doesn't + // appear to be comparable to '2'. + if (relation === comparableRelation && target.flags & TypeFlags.Primitive) { + const constraints = sameMap((source as IntersectionType).types, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOfType(t) || unknownType : t); + if (constraints !== (source as IntersectionType).types) { + source = getIntersectionType(constraints); + if (source.flags & TypeFlags.Never) { + return Ternary.False; + } + if (!(source.flags & TypeFlags.Intersection)) { + return isRelatedTo(source, target, RecursionFlags.Source, /*reportErrors*/ false) || + isRelatedTo(target, source, RecursionFlags.Source, /*reportErrors*/ false); + } + } + } + // Check to see if any constituents of the intersection are immediately related to the target. + // Don't report errors though. Elaborating on whether a source constituent is related to the target is + // not actually useful and leads to some confusing error messages. Instead, we rely on the caller + // checking whether the full intersection viewed as an object is related to the target. + return someTypeRelatedToType(source as IntersectionType, target, /*reportErrors*/ false, IntersectionState.Source); + } + + function eachTypeRelatedToSomeType(source: UnionOrIntersectionType, target: UnionOrIntersectionType): Ternary { + let result = Ternary.True; + const sourceTypes = source.types; + for (const sourceType of sourceTypes) { + const related = typeRelatedToSomeType(sourceType, target, /*reportErrors*/ false, IntersectionState.None); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function typeRelatedToSomeType(source: Type, target: UnionOrIntersectionType, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const targetTypes = target.types; + if (target.flags & TypeFlags.Union) { + if (containsType(targetTypes, source)) { + return Ternary.True; + } + if ( + relation !== comparableRelation && getObjectFlags(target) & ObjectFlags.PrimitiveUnion && !(source.flags & TypeFlags.EnumLiteral) && ( + source.flags & (TypeFlags.StringLiteral | TypeFlags.BooleanLiteral | TypeFlags.BigIntLiteral) || + (relation === subtypeRelation || relation === strictSubtypeRelation) && source.flags & TypeFlags.NumberLiteral + ) + ) { + // When relating a literal type to a union of primitive types, we know the relation is false unless + // the union contains the base primitive type or the literal type in one of its fresh/regular forms. + // We exclude numeric literals for non-subtype relations because numeric literals are assignable to + // numeric enum literals with the same value. Similarly, we exclude enum literal types because + // identically named enum types are related (see isEnumTypeRelatedTo). We exclude the comparable + // relation in entirety because it needs to be checked in both directions. + const alternateForm = source === (source as StringLiteralType).regularType ? (source as StringLiteralType).freshType : (source as StringLiteralType).regularType; + const primitive = source.flags & TypeFlags.StringLiteral ? stringType : + source.flags & TypeFlags.NumberLiteral ? numberType : + source.flags & TypeFlags.BigIntLiteral ? bigintType : + undefined; + return primitive && containsType(targetTypes, primitive) || alternateForm && containsType(targetTypes, alternateForm) ? Ternary.True : Ternary.False; + } + const match = getMatchingUnionConstituentForType(target as UnionType, source); + if (match) { + const related = isRelatedTo(source, match, RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (related) { + return related; + } + } + } + for (const type of targetTypes) { + const related = isRelatedTo(source, type, RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (related) { + return related; + } + } + if (reportErrors) { + // Elaborate only if we can find a best matching type in the target union + const bestMatchingType = getBestMatchingType(source, target, isRelatedTo); + if (bestMatchingType) { + isRelatedTo(source, bestMatchingType, RecursionFlags.Target, /*reportErrors*/ true, /*headMessage*/ undefined, intersectionState); + } + } + return Ternary.False; + } + + function typeRelatedToEachType(source: Type, target: IntersectionType, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + let result = Ternary.True; + const targetTypes = target.types; + for (const targetType of targetTypes) { + const related = isRelatedTo(source, targetType, RecursionFlags.Target, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function someTypeRelatedToType(source: UnionOrIntersectionType, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const sourceTypes = source.types; + if (source.flags & TypeFlags.Union && containsType(sourceTypes, target)) { + return Ternary.True; + } + const len = sourceTypes.length; + for (let i = 0; i < len; i++) { + const related = isRelatedTo(sourceTypes[i], target, RecursionFlags.Source, reportErrors && i === len - 1, /*headMessage*/ undefined, intersectionState); + if (related) { + return related; + } + } + return Ternary.False; + } + + function getUndefinedStrippedTargetIfNeeded(source: Type, target: Type) { + if ( + source.flags & TypeFlags.Union && target.flags & TypeFlags.Union && + !((source as UnionType).types[0].flags & TypeFlags.Undefined) && (target as UnionType).types[0].flags & TypeFlags.Undefined + ) { + return extractTypesOfKind(target, ~TypeFlags.Undefined); + } + return target; + } + + function eachTypeRelatedToType(source: UnionOrIntersectionType, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + let result = Ternary.True; + const sourceTypes = source.types; + // We strip `undefined` from the target if the `source` trivially doesn't contain it for our correspondence-checking fastpath + // since `undefined` is frequently added by optionality and would otherwise spoil a potentially useful correspondence + const undefinedStrippedTarget = getUndefinedStrippedTargetIfNeeded(source, target as UnionType); + for (let i = 0; i < sourceTypes.length; i++) { + const sourceType = sourceTypes[i]; + if (undefinedStrippedTarget.flags & TypeFlags.Union && sourceTypes.length >= (undefinedStrippedTarget as UnionType).types.length && sourceTypes.length % (undefinedStrippedTarget as UnionType).types.length === 0) { + // many unions are mappings of one another; in such cases, simply comparing members at the same index can shortcut the comparison + // such unions will have identical lengths, and their corresponding elements will match up. Another common scenario is where a large + // union has a union of objects intersected with it. In such cases, if the input was, eg `("a" | "b" | "c") & (string | boolean | {} | {whatever})`, + // the result will have the structure `"a" | "b" | "c" | "a" & {} | "b" & {} | "c" & {} | "a" & {whatever} | "b" & {whatever} | "c" & {whatever}` + // - the resulting union has a length which is a multiple of the original union, and the elements correspond modulo the length of the original union + const related = isRelatedTo(sourceType, (undefinedStrippedTarget as UnionType).types[i % (undefinedStrippedTarget as UnionType).types.length], RecursionFlags.Both, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (related) { + result &= related; + continue; + } + } + const related = isRelatedTo(sourceType, target, RecursionFlags.Source, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function typeArgumentsRelatedTo(sources: readonly Type[] = emptyArray, targets: readonly Type[] = emptyArray, variances: readonly VarianceFlags[] = emptyArray, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + if (sources.length !== targets.length && relation === identityRelation) { + return Ternary.False; + } + const length = sources.length <= targets.length ? sources.length : targets.length; + let result = Ternary.True; + for (let i = 0; i < length; i++) { + // When variance information isn't available we default to covariance. This happens + // in the process of computing variance information for recursive types and when + // comparing 'this' type arguments. + const varianceFlags = i < variances.length ? variances[i] : VarianceFlags.Covariant; + const variance = varianceFlags & VarianceFlags.VarianceMask; + // We ignore arguments for independent type parameters (because they're never witnessed). + if (variance !== VarianceFlags.Independent) { + const s = sources[i]; + const t = targets[i]; + let related = Ternary.True; + if (varianceFlags & VarianceFlags.Unmeasurable) { + // Even an `Unmeasurable` variance works out without a structural check if the source and target are _identical_. + // We can't simply assume invariance, because `Unmeasurable` marks nonlinear relations, for example, a relation tained by + // the `-?` modifier in a mapped type (where, no matter how the inputs are related, the outputs still might not be) + related = relation === identityRelation ? isRelatedTo(s, t, RecursionFlags.Both, /*reportErrors*/ false) : compareTypesIdentical(s, t); + } + else if (variance === VarianceFlags.Covariant) { + related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + else if (variance === VarianceFlags.Contravariant) { + related = isRelatedTo(t, s, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + else if (variance === VarianceFlags.Bivariant) { + // In the bivariant case we first compare contravariantly without reporting + // errors. Then, if that doesn't succeed, we compare covariantly with error + // reporting. Thus, error elaboration will be based on the the covariant check, + // which is generally easier to reason about. + related = isRelatedTo(t, s, RecursionFlags.Both, /*reportErrors*/ false); + if (!related) { + related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + } + else { + // In the invariant case we first compare covariantly, and only when that + // succeeds do we proceed to compare contravariantly. Thus, error elaboration + // will typically be based on the covariant check. + related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (related) { + related &= isRelatedTo(t, s, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + } + if (!related) { + return Ternary.False; + } + result &= related; + } + } + return result; + } + + // Determine if possibly recursive types are related. First, check if the result is already available in the global cache. + // Second, check if we have already started a comparison of the given two types in which case we assume the result to be true. + // Third, check if both types are part of deeply nested chains of generic type instantiations and if so assume the types are + // equal and infinitely expanding. Fourth, if we have reached a depth of 100 nested comparisons, assume we have runaway recursion + // and issue an error. Otherwise, actually compare the structure of the two types. + function recursiveTypeRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState, recursionFlags: RecursionFlags): Ternary { + if (overflow) { + return Ternary.False; + } + const id = getRelationKey(source, target, intersectionState, relation, /*ignoreConstraints*/ false); + const entry = relation.get(id); + if (entry !== undefined) { + if (reportErrors && entry & RelationComparisonResult.Failed && !(entry & RelationComparisonResult.Reported)) { + // We are elaborating errors and the cached result is an unreported failure. The result will be reported + // as a failure, and should be updated as a reported failure by the bottom of this function. + } + else { + if (outofbandVarianceMarkerHandler) { + // We're in the middle of variance checking - integrate any unmeasurable/unreliable flags from this cached component + const saved = entry & RelationComparisonResult.ReportsMask; + if (saved & RelationComparisonResult.ReportsUnmeasurable) { + instantiateType(source, reportUnmeasurableMapper); + } + if (saved & RelationComparisonResult.ReportsUnreliable) { + instantiateType(source, reportUnreliableMapper); + } + } + return entry & RelationComparisonResult.Succeeded ? Ternary.True : Ternary.False; + } + } + if (relationCount <= 0) { + overflow = true; + return Ternary.False; + } + if (!maybeKeys) { + maybeKeys = []; + maybeKeysSet = new Set(); + sourceStack = []; + targetStack = []; + } + else { + // If source and target are already being compared, consider them related with assumptions + if (maybeKeysSet.has(id)) { + return Ternary.Maybe; + } + + // A key that starts with "*" is an indication that we have type references that reference constrained + // type parameters. For such keys we also check against the key we would have gotten if all type parameters + // were unconstrained. + const broadestEquivalentId = id.startsWith("*") ? getRelationKey(source, target, intersectionState, relation, /*ignoreConstraints*/ true) : undefined; + if (broadestEquivalentId && maybeKeysSet.has(broadestEquivalentId)) { + return Ternary.Maybe; + } + + if (sourceDepth === 100 || targetDepth === 100) { + overflow = true; + return Ternary.False; + } + } + const maybeStart = maybeCount; + maybeKeys[maybeCount] = id; + maybeKeysSet.add(id); + maybeCount++; + const saveExpandingFlags = expandingFlags; + if (recursionFlags & RecursionFlags.Source) { + sourceStack[sourceDepth] = source; + sourceDepth++; + if (!(expandingFlags & ExpandingFlags.Source) && isDeeplyNestedType(source, sourceStack, sourceDepth)) expandingFlags |= ExpandingFlags.Source; + } + if (recursionFlags & RecursionFlags.Target) { + targetStack[targetDepth] = target; + targetDepth++; + if (!(expandingFlags & ExpandingFlags.Target) && isDeeplyNestedType(target, targetStack, targetDepth)) expandingFlags |= ExpandingFlags.Target; + } + let originalHandler: typeof outofbandVarianceMarkerHandler; + let propagatingVarianceFlags = 0 as RelationComparisonResult; + if (outofbandVarianceMarkerHandler) { + originalHandler = outofbandVarianceMarkerHandler; + outofbandVarianceMarkerHandler = onlyUnreliable => { + propagatingVarianceFlags |= onlyUnreliable ? RelationComparisonResult.ReportsUnreliable : RelationComparisonResult.ReportsUnmeasurable; + return originalHandler!(onlyUnreliable); + }; + } + + let result: Ternary; + if (expandingFlags === ExpandingFlags.Both) { + tracing?.instant(tracing.Phase.CheckTypes, "recursiveTypeRelatedTo_DepthLimit", { + sourceId: source.id, + sourceIdStack: sourceStack.map(t => t.id), + targetId: target.id, + targetIdStack: targetStack.map(t => t.id), + depth: sourceDepth, + targetDepth, + }); + result = Ternary.Maybe; + } + else { + tracing?.push(tracing.Phase.CheckTypes, "structuredTypeRelatedTo", { sourceId: source.id, targetId: target.id }); + result = structuredTypeRelatedTo(source, target, reportErrors, intersectionState); + tracing?.pop(); + } + + if (outofbandVarianceMarkerHandler) { + outofbandVarianceMarkerHandler = originalHandler; + } + if (recursionFlags & RecursionFlags.Source) { + sourceDepth--; + } + if (recursionFlags & RecursionFlags.Target) { + targetDepth--; + } + expandingFlags = saveExpandingFlags; + if (result) { + if (result === Ternary.True || (sourceDepth === 0 && targetDepth === 0)) { + if (result === Ternary.True || result === Ternary.Maybe) { + // If result is definitely true, record all maybe keys as having succeeded. Also, record Ternary.Maybe + // results as having succeeded once we reach depth 0, but never record Ternary.Unknown results. + resetMaybeStack(/*markAllAsSucceeded*/ true); + } + else { + resetMaybeStack(/*markAllAsSucceeded*/ false); + } + } + // Note: it's intentional that we don't reset in the else case; + // we leave them on the stack such that when we hit depth zero + // above, we can report all of them as successful. + } + else { + // A false result goes straight into global cache (when something is false under + // assumptions it will also be false without assumptions) + relation.set(id, (reportErrors ? RelationComparisonResult.Reported : 0) | RelationComparisonResult.Failed | propagatingVarianceFlags); + relationCount--; + resetMaybeStack(/*markAllAsSucceeded*/ false); + } + return result; + + function resetMaybeStack(markAllAsSucceeded: boolean) { + for (let i = maybeStart; i < maybeCount; i++) { + maybeKeysSet.delete(maybeKeys[i]); + if (markAllAsSucceeded) { + relation.set(maybeKeys[i], RelationComparisonResult.Succeeded | propagatingVarianceFlags); + relationCount--; + } + } + maybeCount = maybeStart; + } + } + + function structuredTypeRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const saveErrorInfo = captureErrorCalculationState(); + let result = structuredTypeRelatedToWorker(source, target, reportErrors, intersectionState, saveErrorInfo); + if (relation !== identityRelation) { + // The combined constraint of an intersection type is the intersection of the constraints of + // the constituents. When an intersection type contains instantiable types with union type + // constraints, there are situations where we need to examine the combined constraint. One is + // when the target is a union type. Another is when the intersection contains types belonging + // to one of the disjoint domains. For example, given type variables T and U, each with the + // constraint 'string | number', the combined constraint of 'T & U' is 'string | number' and + // we need to check this constraint against a union on the target side. Also, given a type + // variable V constrained to 'string | number', 'V & number' has a combined constraint of + // 'string & number | number & number' which reduces to just 'number'. + // This also handles type parameters, as a type parameter with a union constraint compared against a union + // needs to have its constraint hoisted into an intersection with said type parameter, this way + // the type param can be compared with itself in the target (with the influence of its constraint to match other parts) + // For example, if `T extends 1 | 2` and `U extends 2 | 3` and we compare `T & U` to `T & U & (1 | 2 | 3)` + if (!result && (source.flags & TypeFlags.Intersection || source.flags & TypeFlags.TypeParameter && target.flags & TypeFlags.Union)) { + const constraint = getEffectiveConstraintOfIntersection(source.flags & TypeFlags.Intersection ? (source as IntersectionType).types : [source], !!(target.flags & TypeFlags.Union)); + if (constraint && everyType(constraint, c => c !== source)) { // Skip comparison if expansion contains the source itself + // TODO: Stack errors so we get a pyramid for the "normal" comparison above, _and_ a second for this + result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + } + } + // When the target is an intersection we need an extra property check in order to detect nested excess + // properties and nested weak types. The following are motivating examples that all should be errors, but + // aren't without this extra property check: + // + // let obj: { a: { x: string } } & { c: number } = { a: { x: 'hello', y: 2 }, c: 5 }; // Nested excess property + // + // declare let wrong: { a: { y: string } }; + // let weak: { a?: { x?: number } } & { c?: string } = wrong; // Nested weak object type + // + if ( + result && !(intersectionState & IntersectionState.Target) && target.flags & TypeFlags.Intersection && + !isGenericObjectType(target) && source.flags & (TypeFlags.Object | TypeFlags.Intersection) + ) { + result &= propertiesRelatedTo(source, target, reportErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ false, IntersectionState.None); + if (result && isObjectLiteralType(source) && getObjectFlags(source) & ObjectFlags.FreshLiteral) { + result &= indexSignaturesRelatedTo(source, target, /*sourceIsPrimitive*/ false, reportErrors, IntersectionState.None); + } + } + // When the source is an intersection we need an extra check of any optional properties in the target to + // detect possible mismatched property types. For example: + // + // function foo(x: { a?: string }, y: T & { a: boolean }) { + // x = y; // Mismatched property in source intersection + // } + // + else if ( + result && isNonGenericObjectType(target) && !isArrayOrTupleType(target) && + source.flags & TypeFlags.Intersection && getApparentType(source).flags & TypeFlags.StructuredType && + !some((source as IntersectionType).types, t => t === target || !!(getObjectFlags(t) & ObjectFlags.NonInferrableType)) + ) { + result &= propertiesRelatedTo(source, target, reportErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ true, intersectionState); + } + } + if (result) { + resetErrorInfo(saveErrorInfo); + } + return result; + } + + function getApparentMappedTypeKeys(nameType: Type, targetType: MappedType) { + const modifiersType = getApparentType(getModifiersTypeFromMappedType(targetType)); + const mappedKeys: Type[] = []; + forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType( + modifiersType, + TypeFlags.StringOrNumberLiteralOrUnique, + /*stringsOnly*/ false, + t => void mappedKeys.push(instantiateType(nameType, appendTypeMapping(targetType.mapper, getTypeParameterFromMappedType(targetType), t))), + ); + return getUnionType(mappedKeys); + } + + function structuredTypeRelatedToWorker(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState, saveErrorInfo: ReturnType): Ternary { + let result: Ternary; + let originalErrorInfo: DiagnosticMessageChain | undefined; + let varianceCheckFailed = false; + let sourceFlags = source.flags; + const targetFlags = target.flags; + if (relation === identityRelation) { + // We've already checked that source.flags and target.flags are identical + if (sourceFlags & TypeFlags.UnionOrIntersection) { + let result = eachTypeRelatedToSomeType(source as UnionOrIntersectionType, target as UnionOrIntersectionType); + if (result) { + result &= eachTypeRelatedToSomeType(target as UnionOrIntersectionType, source as UnionOrIntersectionType); + } + return result; + } + if (sourceFlags & TypeFlags.Index) { + return isRelatedTo((source as IndexType).type, (target as IndexType).type, RecursionFlags.Both, /*reportErrors*/ false); + } + if (sourceFlags & TypeFlags.IndexedAccess) { + if (result = isRelatedTo((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType, RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + } + if (sourceFlags & TypeFlags.Conditional) { + if ((source as ConditionalType).root.isDistributive === (target as ConditionalType).root.isDistributive) { + if (result = isRelatedTo((source as ConditionalType).checkType, (target as ConditionalType).checkType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo((source as ConditionalType).extendsType, (target as ConditionalType).extendsType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo(getTrueTypeFromConditionalType(source as ConditionalType), getTrueTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + } + } + } + } + if (sourceFlags & TypeFlags.Substitution) { + if (result = isRelatedTo((source as SubstitutionType).baseType, (target as SubstitutionType).baseType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo((source as SubstitutionType).constraint, (target as SubstitutionType).constraint, RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + } + if (!(sourceFlags & TypeFlags.Object)) { + return Ternary.False; + } + } + else if (sourceFlags & TypeFlags.UnionOrIntersection || targetFlags & TypeFlags.UnionOrIntersection) { + if (result = unionOrIntersectionRelatedTo(source, target, reportErrors, intersectionState)) { + return result; + } + // The ordered decomposition above doesn't handle all cases. Specifically, we also need to handle: + // Source is instantiable (e.g. source has union or intersection constraint). + // Source is an object, target is a union (e.g. { a, b: boolean } <=> { a, b: true } | { a, b: false }). + // Source is an intersection, target is an object (e.g. { a } & { b } <=> { a, b }). + // Source is an intersection, target is a union (e.g. { a } & { b: boolean } <=> { a, b: true } | { a, b: false }). + // Source is an intersection, target instantiable (e.g. string & { tag } <=> T["a"] constrained to string & { tag }). + if ( + !(sourceFlags & TypeFlags.Instantiable || + sourceFlags & TypeFlags.Object && targetFlags & TypeFlags.Union || + sourceFlags & TypeFlags.Intersection && targetFlags & (TypeFlags.Object | TypeFlags.Union | TypeFlags.Instantiable)) + ) { + return Ternary.False; + } + } + + // We limit alias variance probing to only object and conditional types since their alias behavior + // is more predictable than other, interned types, which may or may not have an alias depending on + // the order in which things were checked. + if ( + sourceFlags & (TypeFlags.Object | TypeFlags.Conditional) && source.aliasSymbol && source.aliasTypeArguments && + source.aliasSymbol === target.aliasSymbol && !(isMarkerType(source) || isMarkerType(target)) + ) { + const variances = getAliasVariances(source.aliasSymbol); + if (variances === emptyArray) { + return Ternary.Unknown; + } + const params = getSymbolLinks(source.aliasSymbol).typeParameters!; + const minParams = getMinTypeArgumentCount(params); + const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + const varianceResult = relateVariances(sourceTypes, targetTypes, variances, intersectionState); + if (varianceResult !== undefined) { + return varianceResult; + } + } + + // For a generic type T and a type U that is assignable to T, [...U] is assignable to T, U is assignable to readonly [...T], + // and U is assignable to [...T] when U is constrained to a mutable array or tuple type. + if ( + isSingleElementGenericTupleType(source) && !source.target.readonly && (result = isRelatedTo(getTypeArguments(source)[0], target, RecursionFlags.Source)) || + isSingleElementGenericTupleType(target) && (target.target.readonly || isMutableArrayOrTuple(getBaseConstraintOfType(source) || source)) && (result = isRelatedTo(source, getTypeArguments(target)[0], RecursionFlags.Target)) + ) { + return result; + } + + if (targetFlags & TypeFlags.TypeParameter) { + // A source type { [P in Q]: X } is related to a target type T if keyof T is related to Q and X is related to T[Q]. + if (getObjectFlags(source) & ObjectFlags.Mapped && !(source as MappedType).declaration.nameType && isRelatedTo(getIndexType(target), getConstraintTypeFromMappedType(source as MappedType), RecursionFlags.Both)) { + if (!(getMappedTypeModifiers(source as MappedType) & MappedTypeModifiers.IncludeOptional)) { + const templateType = getTemplateTypeFromMappedType(source as MappedType); + const indexedAccessType = getIndexedAccessType(target, getTypeParameterFromMappedType(source as MappedType)); + if (result = isRelatedTo(templateType, indexedAccessType, RecursionFlags.Both, reportErrors)) { + return result; + } + } + } + if (relation === comparableRelation && sourceFlags & TypeFlags.TypeParameter) { + // This is a carve-out in comparability to essentially forbid comparing a type parameter + // with another type parameter unless one extends the other. (Remember: comparability is mostly bidirectional!) + let constraint = getConstraintOfTypeParameter(source); + if (constraint) { + while (constraint && someType(constraint, c => !!(c.flags & TypeFlags.TypeParameter))) { + if (result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false)) { + return result; + } + constraint = getConstraintOfTypeParameter(constraint); + } + } + return Ternary.False; + } + } + else if (targetFlags & TypeFlags.Index) { + const targetType = (target as IndexType).type; + // A keyof S is related to a keyof T if T is related to S. + if (sourceFlags & TypeFlags.Index) { + if (result = isRelatedTo(targetType, (source as IndexType).type, RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + if (isTupleType(targetType)) { + // An index type can have a tuple type target when the tuple type contains variadic elements. + // Check if the source is related to the known keys of the tuple type. + if (result = isRelatedTo(source, getKnownKeysOfTupleType(targetType), RecursionFlags.Target, reportErrors)) { + return result; + } + } + else { + // A type S is assignable to keyof T if S is assignable to keyof C, where C is the + // simplified form of T or, if T doesn't simplify, the constraint of T. + const constraint = getSimplifiedTypeOrConstraint(targetType); + if (constraint) { + // We require Ternary.True here such that circular constraints don't cause + // false positives. For example, given 'T extends { [K in keyof T]: string }', + // 'keyof T' has itself as its constraint and produces a Ternary.Maybe when + // related to other types. + if (isRelatedTo(source, getIndexType(constraint, (target as IndexType).indexFlags | IndexFlags.NoReducibleCheck), RecursionFlags.Target, reportErrors) === Ternary.True) { + return Ternary.True; + } + } + else if (isGenericMappedType(targetType)) { + // generic mapped types that don't simplify or have a constraint still have a very simple set of keys we can compare against + // - their nameType or constraintType. + // In many ways, this comparison is a deferred version of what `getIndexTypeForMappedType` does to actually resolve the keys for _non_-generic types + + const nameType = getNameTypeFromMappedType(targetType); + const constraintType = getConstraintTypeFromMappedType(targetType); + let targetKeys; + if (nameType && isMappedTypeWithKeyofConstraintDeclaration(targetType)) { + // we need to get the apparent mappings and union them with the generic mappings, since some properties may be + // missing from the `constraintType` which will otherwise be mapped in the object + const mappedKeys = getApparentMappedTypeKeys(nameType, targetType); + // We still need to include the non-apparent (and thus still generic) keys in the target side of the comparison (in case they're in the source side) + targetKeys = getUnionType([mappedKeys, nameType]); + } + else { + targetKeys = nameType || constraintType; + } + if (isRelatedTo(source, targetKeys, RecursionFlags.Target, reportErrors) === Ternary.True) { + return Ternary.True; + } + } + } + } + else if (targetFlags & TypeFlags.IndexedAccess) { + if (sourceFlags & TypeFlags.IndexedAccess) { + // Relate components directly before falling back to constraint relationships + // A type S[K] is related to a type T[J] if S is related to T and K is related to J. + if (result = isRelatedTo((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType, RecursionFlags.Both, reportErrors)) { + result &= isRelatedTo((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType, RecursionFlags.Both, reportErrors); + } + if (result) { + return result; + } + if (reportErrors) { + originalErrorInfo = errorInfo; + } + } + // A type S is related to a type T[K] if S is related to C, where C is the base + // constraint of T[K] for writing. + if (relation === assignableRelation || relation === comparableRelation) { + const objectType = (target as IndexedAccessType).objectType; + const indexType = (target as IndexedAccessType).indexType; + const baseObjectType = getBaseConstraintOfType(objectType) || objectType; + const baseIndexType = getBaseConstraintOfType(indexType) || indexType; + if (!isGenericObjectType(baseObjectType) && !isGenericIndexType(baseIndexType)) { + const accessFlags = AccessFlags.Writing | (baseObjectType !== objectType ? AccessFlags.NoIndexSignatures : 0); + const constraint = getIndexedAccessTypeOrUndefined(baseObjectType, baseIndexType, accessFlags); + if (constraint) { + if (reportErrors && originalErrorInfo) { + // create a new chain for the constraint error + resetErrorInfo(saveErrorInfo); + } + if (result = isRelatedTo(source, constraint, RecursionFlags.Target, reportErrors, /*headMessage*/ undefined, intersectionState)) { + return result; + } + // prefer the shorter chain of the constraint comparison chain, and the direct comparison chain + if (reportErrors && originalErrorInfo && errorInfo) { + errorInfo = countMessageChainBreadth([originalErrorInfo]) <= countMessageChainBreadth([errorInfo]) ? originalErrorInfo : errorInfo; + } + } + } + } + if (reportErrors) { + originalErrorInfo = undefined; + } + } + else if (isGenericMappedType(target) && relation !== identityRelation) { + // Check if source type `S` is related to target type `{ [P in Q]: T }` or `{ [P in Q as R]: T}`. + const keysRemapped = !!target.declaration.nameType; + const templateType = getTemplateTypeFromMappedType(target); + const modifiers = getMappedTypeModifiers(target); + if (!(modifiers & MappedTypeModifiers.ExcludeOptional)) { + // If the mapped type has shape `{ [P in Q]: T[P] }`, + // source `S` is related to target if `T` = `S`, i.e. `S` is related to `{ [P in Q]: S[P] }`. + if ( + !keysRemapped && templateType.flags & TypeFlags.IndexedAccess && (templateType as IndexedAccessType).objectType === source && + (templateType as IndexedAccessType).indexType === getTypeParameterFromMappedType(target) + ) { + return Ternary.True; + } + if (!isGenericMappedType(source)) { + // If target has shape `{ [P in Q as R]: T}`, then its keys have type `R`. + // If target has shape `{ [P in Q]: T }`, then its keys have type `Q`. + const targetKeys = keysRemapped ? getNameTypeFromMappedType(target)! : getConstraintTypeFromMappedType(target); + // Type of the keys of source type `S`, i.e. `keyof S`. + const sourceKeys = getIndexType(source, IndexFlags.NoIndexSignatures); + const includeOptional = modifiers & MappedTypeModifiers.IncludeOptional; + const filteredByApplicability = includeOptional ? intersectTypes(targetKeys, sourceKeys) : undefined; + // A source type `S` is related to a target type `{ [P in Q]: T }` if `Q` is related to `keyof S` and `S[Q]` is related to `T`. + // A source type `S` is related to a target type `{ [P in Q as R]: T }` if `R` is related to `keyof S` and `S[R]` is related to `T. + // A source type `S` is related to a target type `{ [P in Q]?: T }` if some constituent `Q'` of `Q` is related to `keyof S` and `S[Q']` is related to `T`. + // A source type `S` is related to a target type `{ [P in Q as R]?: T }` if some constituent `R'` of `R` is related to `keyof S` and `S[R']` is related to `T`. + if ( + includeOptional + ? !(filteredByApplicability!.flags & TypeFlags.Never) + : isRelatedTo(targetKeys, sourceKeys, RecursionFlags.Both) + ) { + const templateType = getTemplateTypeFromMappedType(target); + const typeParameter = getTypeParameterFromMappedType(target); + + // Fastpath: When the template type has the form `Obj[P]` where `P` is the mapped type parameter, directly compare source `S` with `Obj` + // to avoid creating the (potentially very large) number of new intermediate types made by manufacturing `S[P]`. + const nonNullComponent = extractTypesOfKind(templateType, ~TypeFlags.Nullable); + if (!keysRemapped && nonNullComponent.flags & TypeFlags.IndexedAccess && (nonNullComponent as IndexedAccessType).indexType === typeParameter) { + if (result = isRelatedTo(source, (nonNullComponent as IndexedAccessType).objectType, RecursionFlags.Target, reportErrors)) { + return result; + } + } + else { + // We need to compare the type of a property on the source type `S` to the type of the same property on the target type, + // so we need to construct an indexing type representing a property, and then use indexing type to index the source type for comparison. + + // If the target type has shape `{ [P in Q]: T }`, then a property of the target has type `P`. + // If the target type has shape `{ [P in Q]?: T }`, then a property of the target has type `P`, + // but the property is optional, so we only want to compare properties `P` that are common between `keyof S` and `Q`. + // If the target type has shape `{ [P in Q as R]: T }`, then a property of the target has type `R`. + // If the target type has shape `{ [P in Q as R]?: T }`, then a property of the target has type `R`, + // but the property is optional, so we only want to compare properties `R` that are common between `keyof S` and `R`. + const indexingType = keysRemapped + ? (filteredByApplicability || targetKeys) + : filteredByApplicability + ? getIntersectionType([filteredByApplicability, typeParameter]) + : typeParameter; + const indexedAccessType = getIndexedAccessType(source, indexingType); + // Compare `S[indexingType]` to `T`, where `T` is the type of a property of the target type. + if (result = isRelatedTo(indexedAccessType, templateType, RecursionFlags.Both, reportErrors)) { + return result; + } + } + } + originalErrorInfo = errorInfo; + resetErrorInfo(saveErrorInfo); + } + } + } + else if (targetFlags & TypeFlags.Conditional) { + // If we reach 10 levels of nesting for the same conditional type, assume it is an infinitely expanding recursive + // conditional type and bail out with a Ternary.Maybe result. + if (isDeeplyNestedType(target, targetStack, targetDepth, 10)) { + return Ternary.Maybe; + } + const c = target as ConditionalType; + // We check for a relationship to a conditional type target only when the conditional type has no + // 'infer' positions, is not distributive or is distributive but doesn't reference the check type + // parameter in either of the result types, and the source isn't an instantiation of the same + // conditional type (as happens when computing variance). + if (!c.root.inferTypeParameters && !isDistributionDependent(c.root) && !(source.flags & TypeFlags.Conditional && (source as ConditionalType).root === c.root)) { + // Check if the conditional is always true or always false but still deferred for distribution purposes. + const skipTrue = !isTypeAssignableTo(getPermissiveInstantiation(c.checkType), getPermissiveInstantiation(c.extendsType)); + const skipFalse = !skipTrue && isTypeAssignableTo(getRestrictiveInstantiation(c.checkType), getRestrictiveInstantiation(c.extendsType)); + // TODO: Find a nice way to include potential conditional type breakdowns in error output, if they seem good (they usually don't) + if (result = skipTrue ? Ternary.True : isRelatedTo(source, getTrueTypeFromConditionalType(c), RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState)) { + result &= skipFalse ? Ternary.True : isRelatedTo(source, getFalseTypeFromConditionalType(c), RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (result) { + return result; + } + } + } + } + else if (targetFlags & TypeFlags.TemplateLiteral) { + if (sourceFlags & TypeFlags.TemplateLiteral) { + if (relation === comparableRelation) { + return templateLiteralTypesDefinitelyUnrelated(source as TemplateLiteralType, target as TemplateLiteralType) ? Ternary.False : Ternary.True; + } + // Report unreliable variance for type variables referenced in template literal type placeholders. + // For example, `foo-${number}` is related to `foo-${string}` even though number isn't related to string. + instantiateType(source, reportUnreliableMapper); + } + if (isTypeMatchedByTemplateLiteralType(source, target as TemplateLiteralType)) { + return Ternary.True; + } + } + else if (target.flags & TypeFlags.StringMapping) { + if (!(source.flags & TypeFlags.StringMapping)) { + if (isMemberOfStringMapping(source, target)) { + return Ternary.True; + } + } + } + + if (sourceFlags & TypeFlags.TypeVariable) { + // IndexedAccess comparisons are handled above in the `targetFlags & TypeFlage.IndexedAccess` branch + if (!(sourceFlags & TypeFlags.IndexedAccess && targetFlags & TypeFlags.IndexedAccess)) { + const constraint = getConstraintOfType(source as TypeVariable) || unknownType; + // hi-speed no-this-instantiation check (less accurate, but avoids costly `this`-instantiation when the constraint will suffice), see #28231 for report on why this is needed + if (result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState)) { + return result; + } + // slower, fuller, this-instantiated check (necessary when comparing raw `this` types from base classes), see `subclassWithPolymorphicThisIsAssignable.ts` test for example + else if (result = isRelatedTo(getTypeWithThisArgument(constraint, source), target, RecursionFlags.Source, reportErrors && constraint !== unknownType && !(targetFlags & sourceFlags & TypeFlags.TypeParameter), /*headMessage*/ undefined, intersectionState)) { + return result; + } + if (isMappedTypeGenericIndexedAccess(source)) { + // For an indexed access type { [P in K]: E}[X], above we have already explored an instantiation of E with X + // substituted for P. We also want to explore type { [P in K]: E }[C], where C is the constraint of X. + const indexConstraint = getConstraintOfType((source as IndexedAccessType).indexType); + if (indexConstraint) { + if (result = isRelatedTo(getIndexedAccessType((source as IndexedAccessType).objectType, indexConstraint), target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + } + } + } + else if (sourceFlags & TypeFlags.Index) { + const isDeferredMappedIndex = shouldDeferIndexType((source as IndexType).type, (source as IndexType).indexFlags) && getObjectFlags((source as IndexType).type) & ObjectFlags.Mapped; + if (result = isRelatedTo(stringNumberSymbolType, target, RecursionFlags.Source, reportErrors && !isDeferredMappedIndex)) { + return result; + } + if (isDeferredMappedIndex) { + const mappedType = (source as IndexType).type as MappedType; + const nameType = getNameTypeFromMappedType(mappedType); + // Unlike on the target side, on the source side we do *not* include the generic part of the `nameType`, since that comes from a + // (potentially anonymous) mapped type local type parameter, so that'd never assign outside the mapped type body, but we still want to + // allow assignments of index types of identical (or similar enough) mapped types. + // eg, `keyof {[X in keyof A]: Obj[X]}` should be assignable to `keyof {[Y in keyof A]: Tup[Y]}` because both map over the same set of keys (`keyof A`). + // Without this source-side breakdown, a `keyof {[X in keyof A]: Obj[X]}` style type won't be assignable to anything except itself, which is much too strict. + const sourceMappedKeys = nameType && isMappedTypeWithKeyofConstraintDeclaration(mappedType) ? getApparentMappedTypeKeys(nameType, mappedType) : (nameType || getConstraintTypeFromMappedType(mappedType)); + if (result = isRelatedTo(sourceMappedKeys, target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + } + else if (sourceFlags & TypeFlags.TemplateLiteral && !(targetFlags & TypeFlags.Object)) { + if (!(targetFlags & TypeFlags.TemplateLiteral)) { + const constraint = getBaseConstraintOfType(source); + if (constraint && constraint !== source && (result = isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors))) { + return result; + } + } + } + else if (sourceFlags & TypeFlags.StringMapping) { + if (targetFlags & TypeFlags.StringMapping) { + if ((source as StringMappingType).symbol !== (target as StringMappingType).symbol) { + return Ternary.False; + } + if (result = isRelatedTo((source as StringMappingType).type, (target as StringMappingType).type, RecursionFlags.Both, reportErrors)) { + return result; + } + } + else { + const constraint = getBaseConstraintOfType(source); + if (constraint && (result = isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors))) { + return result; + } + } + } + else if (sourceFlags & TypeFlags.Conditional) { + // If we reach 10 levels of nesting for the same conditional type, assume it is an infinitely expanding recursive + // conditional type and bail out with a Ternary.Maybe result. + if (isDeeplyNestedType(source, sourceStack, sourceDepth, 10)) { + return Ternary.Maybe; + } + if (targetFlags & TypeFlags.Conditional) { + // Two conditional types 'T1 extends U1 ? X1 : Y1' and 'T2 extends U2 ? X2 : Y2' are related if + // one of T1 and T2 is related to the other, U1 and U2 are identical types, X1 is related to X2, + // and Y1 is related to Y2. + const sourceParams = (source as ConditionalType).root.inferTypeParameters; + let sourceExtends = (source as ConditionalType).extendsType; + let mapper: TypeMapper | undefined; + if (sourceParams) { + // If the source has infer type parameters, we instantiate them in the context of the target + const ctx = createInferenceContext(sourceParams, /*signature*/ undefined, InferenceFlags.None, isRelatedToWorker); + inferTypes(ctx.inferences, (target as ConditionalType).extendsType, sourceExtends, InferencePriority.NoConstraints | InferencePriority.AlwaysStrict); + sourceExtends = instantiateType(sourceExtends, ctx.mapper); + mapper = ctx.mapper; + } + if ( + isTypeIdenticalTo(sourceExtends, (target as ConditionalType).extendsType) && + (isRelatedTo((source as ConditionalType).checkType, (target as ConditionalType).checkType, RecursionFlags.Both) || isRelatedTo((target as ConditionalType).checkType, (source as ConditionalType).checkType, RecursionFlags.Both)) + ) { + if (result = isRelatedTo(instantiateType(getTrueTypeFromConditionalType(source as ConditionalType), mapper), getTrueTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, reportErrors)) { + result &= isRelatedTo(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, reportErrors); + } + if (result) { + return result; + } + } + } + // conditionals can be related to one another via normal constraint, as, eg, `A extends B ? O : never` should be assignable to `O` + // when `O` is a conditional (`never` is trivially assignable to `O`, as is `O`!). + const defaultConstraint = getDefaultConstraintOfConditionalType(source as ConditionalType); + if (defaultConstraint) { + if (result = isRelatedTo(defaultConstraint, target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + // conditionals aren't related to one another via distributive constraint as it is much too inaccurate and allows way + // more assignments than are desirable (since it maps the source check type to its constraint, it loses information). + const distributiveConstraint = !(targetFlags & TypeFlags.Conditional) && hasNonCircularBaseConstraint(source) ? getConstraintOfDistributiveConditionalType(source as ConditionalType) : undefined; + if (distributiveConstraint) { + resetErrorInfo(saveErrorInfo); + if (result = isRelatedTo(distributiveConstraint, target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + } + else { + // An empty object type is related to any mapped type that includes a '?' modifier. + if (relation !== subtypeRelation && relation !== strictSubtypeRelation && isPartialMappedType(target) && isEmptyObjectType(source)) { + return Ternary.True; + } + if (isGenericMappedType(target)) { + if (isGenericMappedType(source)) { + if (result = mappedTypeRelatedTo(source, target, reportErrors)) { + return result; + } + } + return Ternary.False; + } + const sourceIsPrimitive = !!(sourceFlags & TypeFlags.Primitive); + if (relation !== identityRelation) { + source = getApparentType(source); + sourceFlags = source.flags; + } + else if (isGenericMappedType(source)) { + return Ternary.False; + } + if ( + getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (source as TypeReference).target === (target as TypeReference).target && + !isTupleType(source) && !(isMarkerType(source) || isMarkerType(target)) + ) { + // When strictNullChecks is disabled, the element type of the empty array literal is undefinedWideningType, + // and an empty array literal wouldn't be assignable to a `never[]` without this check. + if (isEmptyArrayLiteralType(source)) { + return Ternary.True; + } + // We have type references to the same generic type, and the type references are not marker + // type references (which are intended by be compared structurally). Obtain the variance + // information for the type parameters and relate the type arguments accordingly. + const variances = getVariances((source as TypeReference).target); + // We return Ternary.Maybe for a recursive invocation of getVariances (signalled by emptyArray). This + // effectively means we measure variance only from type parameter occurrences that aren't nested in + // recursive instantiations of the generic type. + if (variances === emptyArray) { + return Ternary.Unknown; + } + const varianceResult = relateVariances(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), variances, intersectionState); + if (varianceResult !== undefined) { + return varianceResult; + } + } + else if (isReadonlyArrayType(target) ? everyType(source, isArrayOrTupleType) : isArrayType(target) && everyType(source, t => isTupleType(t) && !t.target.readonly)) { + if (relation !== identityRelation) { + return isRelatedTo(getIndexTypeOfType(source, numberType) || anyType, getIndexTypeOfType(target, numberType) || anyType, RecursionFlags.Both, reportErrors); + } + else { + // By flags alone, we know that the `target` is a readonly array while the source is a normal array or tuple + // or `target` is an array and source is a tuple - in both cases the types cannot be identical, by construction + return Ternary.False; + } + } + else if (isGenericTupleType(source) && isTupleType(target) && !isGenericTupleType(target)) { + const constraint = getBaseConstraintOrType(source); + if (constraint !== source) { + return isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors); + } + } + // A fresh empty object type is never a subtype of a non-empty object type. This ensures fresh({}) <: { [x: string]: xxx } + // but not vice-versa. Without this rule, those types would be mutual subtypes. + else if ((relation === subtypeRelation || relation === strictSubtypeRelation) && isEmptyObjectType(target) && getObjectFlags(target) & ObjectFlags.FreshLiteral && !isEmptyObjectType(source)) { + return Ternary.False; + } + // Even if relationship doesn't hold for unions, intersections, or generic type references, + // it may hold in a structural comparison. + // In a check of the form X = A & B, we will have previously checked if A relates to X or B relates + // to X. Failing both of those we want to check if the aggregation of A and B's members structurally + // relates to X. Thus, we include intersection types on the source side here. + if (sourceFlags & (TypeFlags.Object | TypeFlags.Intersection) && targetFlags & TypeFlags.Object) { + // Report structural errors only if we haven't reported any errors yet + const reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo.errorInfo && !sourceIsPrimitive; + result = propertiesRelatedTo(source, target, reportStructuralErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ false, intersectionState); + if (result) { + result &= signaturesRelatedTo(source, target, SignatureKind.Call, reportStructuralErrors, intersectionState); + if (result) { + result &= signaturesRelatedTo(source, target, SignatureKind.Construct, reportStructuralErrors, intersectionState); + if (result) { + result &= indexSignaturesRelatedTo(source, target, sourceIsPrimitive, reportStructuralErrors, intersectionState); + } + } + } + if (varianceCheckFailed && result) { + errorInfo = originalErrorInfo || errorInfo || saveErrorInfo.errorInfo; // Use variance error (there is no structural one) and return false + } + else if (result) { + return result; + } + } + // If S is an object type and T is a discriminated union, S may be related to T if + // there exists a constituent of T for every combination of the discriminants of S + // with respect to T. We do not report errors here, as we will use the existing + // error result from checking each constituent of the union. + if (sourceFlags & (TypeFlags.Object | TypeFlags.Intersection) && targetFlags & TypeFlags.Union) { + const objectOnlyTarget = extractTypesOfKind(target, TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Substitution); + if (objectOnlyTarget.flags & TypeFlags.Union) { + const result = typeRelatedToDiscriminatedType(source, objectOnlyTarget as UnionType); + if (result) { + return result; + } + } + } + } + return Ternary.False; + + function countMessageChainBreadth(info: DiagnosticMessageChain[] | undefined): number { + if (!info) return 0; + return reduceLeft(info, (value, chain) => value + 1 + countMessageChainBreadth(chain.next), 0); + } + + function relateVariances(sourceTypeArguments: readonly Type[] | undefined, targetTypeArguments: readonly Type[] | undefined, variances: VarianceFlags[], intersectionState: IntersectionState) { + if (result = typeArgumentsRelatedTo(sourceTypeArguments, targetTypeArguments, variances, reportErrors, intersectionState)) { + return result; + } + if (some(variances, v => !!(v & VarianceFlags.AllowsStructuralFallback))) { + // If some type parameter was `Unmeasurable` or `Unreliable`, and we couldn't pass by assuming it was identical, then we + // have to allow a structural fallback check + // We elide the variance-based error elaborations, since those might not be too helpful, since we'll potentially + // be assuming identity of the type parameter. + originalErrorInfo = undefined; + resetErrorInfo(saveErrorInfo); + return undefined; + } + const allowStructuralFallback = targetTypeArguments && hasCovariantVoidArgument(targetTypeArguments, variances); + varianceCheckFailed = !allowStructuralFallback; + // The type arguments did not relate appropriately, but it may be because we have no variance + // information (in which case typeArgumentsRelatedTo defaulted to covariance for all type + // arguments). It might also be the case that the target type has a 'void' type argument for + // a covariant type parameter that is only used in return positions within the generic type + // (in which case any type argument is permitted on the source side). In those cases we proceed + // with a structural comparison. Otherwise, we know for certain the instantiations aren't + // related and we can return here. + if (variances !== emptyArray && !allowStructuralFallback) { + // In some cases generic types that are covariant in regular type checking mode become + // invariant in --strictFunctionTypes mode because one or more type parameters are used in + // both co- and contravariant positions. In order to make it easier to diagnose *why* such + // types are invariant, if any of the type parameters are invariant we reset the reported + // errors and instead force a structural comparison (which will include elaborations that + // reveal the reason). + // We can switch on `reportErrors` here, since varianceCheckFailed guarantees we return `False`, + // we can return `False` early here to skip calculating the structural error message we don't need. + if (varianceCheckFailed && !(reportErrors && some(variances, v => (v & VarianceFlags.VarianceMask) === VarianceFlags.Invariant))) { + return Ternary.False; + } + // We remember the original error information so we can restore it in case the structural + // comparison unexpectedly succeeds. This can happen when the structural comparison result + // is a Ternary.Maybe for example caused by the recursion depth limiter. + originalErrorInfo = errorInfo; + resetErrorInfo(saveErrorInfo); + } + } + } + + // A type [P in S]: X is related to a type [Q in T]: Y if T is related to S and X' is + // related to Y, where X' is an instantiation of X in which P is replaced with Q. Notice + // that S and T are contra-variant whereas X and Y are co-variant. + function mappedTypeRelatedTo(source: MappedType, target: MappedType, reportErrors: boolean): Ternary { + const modifiersRelated = relation === comparableRelation || (relation === identityRelation ? getMappedTypeModifiers(source) === getMappedTypeModifiers(target) : + getCombinedMappedTypeOptionality(source) <= getCombinedMappedTypeOptionality(target)); + if (modifiersRelated) { + let result: Ternary; + const targetConstraint = getConstraintTypeFromMappedType(target); + const sourceConstraint = instantiateType(getConstraintTypeFromMappedType(source), getCombinedMappedTypeOptionality(source) < 0 ? reportUnmeasurableMapper : reportUnreliableMapper); + if (result = isRelatedTo(targetConstraint, sourceConstraint, RecursionFlags.Both, reportErrors)) { + const mapper = createTypeMapper([getTypeParameterFromMappedType(source)], [getTypeParameterFromMappedType(target)]); + if (instantiateType(getNameTypeFromMappedType(source), mapper) === instantiateType(getNameTypeFromMappedType(target), mapper)) { + return result & isRelatedTo(instantiateType(getTemplateTypeFromMappedType(source), mapper), getTemplateTypeFromMappedType(target), RecursionFlags.Both, reportErrors); + } + } + } + return Ternary.False; + } + + function typeRelatedToDiscriminatedType(source: Type, target: UnionType) { + // 1. Generate the combinations of discriminant properties & types 'source' can satisfy. + // a. If the number of combinations is above a set limit, the comparison is too complex. + // 2. Filter 'target' to the subset of types whose discriminants exist in the matrix. + // a. If 'target' does not satisfy all discriminants in the matrix, 'source' is not related. + // 3. For each type in the filtered 'target', determine if all non-discriminant properties of + // 'target' are related to a property in 'source'. + // + // NOTE: See ~/tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithDiscriminatedUnion.ts + // for examples. + + const sourceProperties = getPropertiesOfType(source); + const sourcePropertiesFiltered = findDiscriminantProperties(sourceProperties, target); + if (!sourcePropertiesFiltered) return Ternary.False; + + // Though we could compute the number of combinations as we generate + // the matrix, this would incur additional memory overhead due to + // array allocations. To reduce this overhead, we first compute + // the number of combinations to ensure we will not surpass our + // fixed limit before incurring the cost of any allocations: + let numCombinations = 1; + for (const sourceProperty of sourcePropertiesFiltered) { + numCombinations *= countTypes(getNonMissingTypeOfSymbol(sourceProperty)); + if (numCombinations > 25) { + // We've reached the complexity limit. + tracing?.instant(tracing.Phase.CheckTypes, "typeRelatedToDiscriminatedType_DepthLimit", { sourceId: source.id, targetId: target.id, numCombinations }); + return Ternary.False; + } + } + + // Compute the set of types for each discriminant property. + const sourceDiscriminantTypes: Type[][] = new Array(sourcePropertiesFiltered.length); + const excludedProperties = new Set<__String>(); + for (let i = 0; i < sourcePropertiesFiltered.length; i++) { + const sourceProperty = sourcePropertiesFiltered[i]; + const sourcePropertyType = getNonMissingTypeOfSymbol(sourceProperty); + sourceDiscriminantTypes[i] = sourcePropertyType.flags & TypeFlags.Union + ? (sourcePropertyType as UnionType).types + : [sourcePropertyType]; + excludedProperties.add(sourceProperty.escapedName); + } + + // Match each combination of the cartesian product of discriminant properties to one or more + // constituents of 'target'. If any combination does not have a match then 'source' is not relatable. + const discriminantCombinations = cartesianProduct(sourceDiscriminantTypes); + const matchingTypes: Type[] = []; + for (const combination of discriminantCombinations) { + let hasMatch = false; + outer: + for (const type of target.types) { + for (let i = 0; i < sourcePropertiesFiltered.length; i++) { + const sourceProperty = sourcePropertiesFiltered[i]; + const targetProperty = getPropertyOfType(type, sourceProperty.escapedName); + if (!targetProperty) continue outer; + if (sourceProperty === targetProperty) continue; + // We compare the source property to the target in the context of a single discriminant type. + const related = propertyRelatedTo(source, target, sourceProperty, targetProperty, _ => combination[i], /*reportErrors*/ false, IntersectionState.None, /*skipOptional*/ strictNullChecks || relation === comparableRelation); + // If the target property could not be found, or if the properties were not related, + // then this constituent is not a match. + if (!related) { + continue outer; + } + } + pushIfUnique(matchingTypes, type, equateValues); + hasMatch = true; + } + if (!hasMatch) { + // We failed to match any type for this combination. + return Ternary.False; + } + } + + // Compare the remaining non-discriminant properties of each match. + let result = Ternary.True; + for (const type of matchingTypes) { + result &= propertiesRelatedTo(source, type, /*reportErrors*/ false, excludedProperties, /*optionalsOnly*/ false, IntersectionState.None); + if (result) { + result &= signaturesRelatedTo(source, type, SignatureKind.Call, /*reportErrors*/ false, IntersectionState.None); + if (result) { + result &= signaturesRelatedTo(source, type, SignatureKind.Construct, /*reportErrors*/ false, IntersectionState.None); + if (result && !(isTupleType(source) && isTupleType(type))) { + // Comparing numeric index types when both `source` and `type` are tuples is unnecessary as the + // element types should be sufficiently covered by `propertiesRelatedTo`. It also causes problems + // with index type assignability as the types for the excluded discriminants are still included + // in the index type. + result &= indexSignaturesRelatedTo(source, type, /*sourceIsPrimitive*/ false, /*reportErrors*/ false, IntersectionState.None); + } + } + } + if (!result) { + return result; + } + } + return result; + } + + function excludeProperties(properties: Symbol[], excludedProperties: Set<__String> | undefined) { + if (!excludedProperties || properties.length === 0) return properties; + let result: Symbol[] | undefined; + for (let i = 0; i < properties.length; i++) { + if (!excludedProperties.has(properties[i].escapedName)) { + if (result) { + result.push(properties[i]); + } + } + else if (!result) { + result = properties.slice(0, i); + } + } + return result || properties; + } + + function isPropertySymbolTypeRelated(sourceProp: Symbol, targetProp: Symbol, getTypeOfSourceProperty: (sym: Symbol) => Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const targetIsOptional = strictNullChecks && !!(getCheckFlags(targetProp) & CheckFlags.Partial); + const effectiveTarget = addOptionality(getNonMissingTypeOfSymbol(targetProp), /*isProperty*/ false, targetIsOptional); + const effectiveSource = getTypeOfSourceProperty(sourceProp); + return isRelatedTo(effectiveSource, effectiveTarget, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + + function propertyRelatedTo(source: Type, target: Type, sourceProp: Symbol, targetProp: Symbol, getTypeOfSourceProperty: (sym: Symbol) => Type, reportErrors: boolean, intersectionState: IntersectionState, skipOptional: boolean): Ternary { + const sourcePropFlags = getDeclarationModifierFlagsFromSymbol(sourceProp); + const targetPropFlags = getDeclarationModifierFlagsFromSymbol(targetProp); + if (sourcePropFlags & ModifierFlags.Private || targetPropFlags & ModifierFlags.Private) { + if (sourceProp.valueDeclaration !== targetProp.valueDeclaration) { + if (reportErrors) { + if (sourcePropFlags & ModifierFlags.Private && targetPropFlags & ModifierFlags.Private) { + reportError(Diagnostics.Types_have_separate_declarations_of_a_private_property_0, symbolToString(targetProp)); + } + else { + reportError(Diagnostics.Property_0_is_private_in_type_1_but_not_in_type_2, symbolToString(targetProp), typeToString(sourcePropFlags & ModifierFlags.Private ? source : target), typeToString(sourcePropFlags & ModifierFlags.Private ? target : source)); + } + } + return Ternary.False; + } + } + else if (targetPropFlags & ModifierFlags.Protected) { + if (!isValidOverrideOf(sourceProp, targetProp)) { + if (reportErrors) { + reportError(Diagnostics.Property_0_is_protected_but_type_1_is_not_a_class_derived_from_2, symbolToString(targetProp), typeToString(getDeclaringClass(sourceProp) || source), typeToString(getDeclaringClass(targetProp) || target)); + } + return Ternary.False; + } + } + else if (sourcePropFlags & ModifierFlags.Protected) { + if (reportErrors) { + reportError(Diagnostics.Property_0_is_protected_in_type_1_but_public_in_type_2, symbolToString(targetProp), typeToString(source), typeToString(target)); + } + return Ternary.False; + } + + // Ensure {readonly a: whatever} is not a subtype of {a: whatever}, + // while {a: whatever} is a subtype of {readonly a: whatever}. + // This ensures the subtype relationship is ordered, and preventing declaration order + // from deciding which type "wins" in union subtype reduction. + // They're still assignable to one another, since `readonly` doesn't affect assignability. + // This is only applied during the strictSubtypeRelation -- currently used in subtype reduction + if ( + relation === strictSubtypeRelation && + isReadonlySymbol(sourceProp) && !isReadonlySymbol(targetProp) + ) { + return Ternary.False; + } + // If the target comes from a partial union prop, allow `undefined` in the target type + const related = isPropertySymbolTypeRelated(sourceProp, targetProp, getTypeOfSourceProperty, reportErrors, intersectionState); + if (!related) { + if (reportErrors) { + reportIncompatibleError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(targetProp)); + } + return Ternary.False; + } + // When checking for comparability, be more lenient with optional properties. + if (!skipOptional && sourceProp.flags & SymbolFlags.Optional && targetProp.flags & SymbolFlags.ClassMember && !(targetProp.flags & SymbolFlags.Optional)) { + // TypeScript 1.0 spec (April 2014): 3.8.3 + // S is a subtype of a type T, and T is a supertype of S if ... + // S' and T are object types and, for each member M in T.. + // M is a property and S' contains a property N where + // if M is a required property, N is also a required property + // (M - property in T) + // (N - property in S) + if (reportErrors) { + reportError(Diagnostics.Property_0_is_optional_in_type_1_but_required_in_type_2, symbolToString(targetProp), typeToString(source), typeToString(target)); + } + return Ternary.False; + } + return related; + } + + function reportUnmatchedProperty(source: Type, target: Type, unmatchedProperty: Symbol, requireOptionalProperties: boolean) { + let shouldSkipElaboration = false; + // give specific error in case where private names have the same description + if ( + unmatchedProperty.valueDeclaration + && isNamedDeclaration(unmatchedProperty.valueDeclaration) + && isPrivateIdentifier(unmatchedProperty.valueDeclaration.name) + && source.symbol + && source.symbol.flags & SymbolFlags.Class + ) { + const privateIdentifierDescription = unmatchedProperty.valueDeclaration.name.escapedText; + const symbolTableKey = getSymbolNameForPrivateIdentifier(source.symbol, privateIdentifierDescription); + if (symbolTableKey && getPropertyOfType(source, symbolTableKey)) { + const sourceName = factory.getDeclarationName(source.symbol.valueDeclaration); + const targetName = factory.getDeclarationName(target.symbol.valueDeclaration); + reportError( + Diagnostics.Property_0_in_type_1_refers_to_a_different_member_that_cannot_be_accessed_from_within_type_2, + diagnosticName(privateIdentifierDescription), + diagnosticName(sourceName.escapedText === "" ? anon : sourceName), + diagnosticName(targetName.escapedText === "" ? anon : targetName), + ); + return; + } + } + const props = arrayFrom(getUnmatchedProperties(source, target, requireOptionalProperties, /*matchDiscriminantProperties*/ false)); + if ( + !headMessage || (headMessage.code !== Diagnostics.Class_0_incorrectly_implements_interface_1.code && + headMessage.code !== Diagnostics.Class_0_incorrectly_implements_class_1_Did_you_mean_to_extend_1_and_inherit_its_members_as_a_subclass.code) + ) { + shouldSkipElaboration = true; // Retain top-level error for interface implementing issues, otherwise omit it + } + if (props.length === 1) { + const propName = symbolToString(unmatchedProperty, /*enclosingDeclaration*/ undefined, SymbolFlags.None, SymbolFormatFlags.AllowAnyNodeKind | SymbolFormatFlags.WriteComputedProps); + reportError(Diagnostics.Property_0_is_missing_in_type_1_but_required_in_type_2, propName, ...getTypeNamesForErrorDisplay(source, target)); + if (length(unmatchedProperty.declarations)) { + associateRelatedInfo(createDiagnosticForNode(unmatchedProperty.declarations![0], Diagnostics._0_is_declared_here, propName)); + } + if (shouldSkipElaboration && errorInfo) { + overrideNextErrorInfo++; + } + } + else if (tryElaborateArrayLikeErrors(source, target, /*reportErrors*/ false)) { + if (props.length > 5) { // arbitrary cutoff for too-long list form + reportError(Diagnostics.Type_0_is_missing_the_following_properties_from_type_1_Colon_2_and_3_more, typeToString(source), typeToString(target), map(props.slice(0, 4), p => symbolToString(p)).join(", "), props.length - 4); + } + else { + reportError(Diagnostics.Type_0_is_missing_the_following_properties_from_type_1_Colon_2, typeToString(source), typeToString(target), map(props, p => symbolToString(p)).join(", ")); + } + if (shouldSkipElaboration && errorInfo) { + overrideNextErrorInfo++; + } + } + // No array like or unmatched property error - just issue top level error (errorInfo = undefined) + } + + function propertiesRelatedTo(source: Type, target: Type, reportErrors: boolean, excludedProperties: Set<__String> | undefined, optionalsOnly: boolean, intersectionState: IntersectionState): Ternary { + if (relation === identityRelation) { + return propertiesIdenticalTo(source, target, excludedProperties); + } + let result = Ternary.True; + if (isTupleType(target)) { + if (isArrayOrTupleType(source)) { + if (!target.target.readonly && (isReadonlyArrayType(source) || isTupleType(source) && source.target.readonly)) { + return Ternary.False; + } + const sourceArity = getTypeReferenceArity(source); + const targetArity = getTypeReferenceArity(target); + const sourceRestFlag = isTupleType(source) ? source.target.combinedFlags & ElementFlags.Rest : ElementFlags.Rest; + const targetHasRestElement = !!(target.target.combinedFlags & ElementFlags.Variable); + const sourceMinLength = isTupleType(source) ? source.target.minLength : 0; + const targetMinLength = target.target.minLength; + if (!sourceRestFlag && sourceArity < targetMinLength) { + if (reportErrors) { + reportError(Diagnostics.Source_has_0_element_s_but_target_requires_1, sourceArity, targetMinLength); + } + return Ternary.False; + } + if (!targetHasRestElement && targetArity < sourceMinLength) { + if (reportErrors) { + reportError(Diagnostics.Source_has_0_element_s_but_target_allows_only_1, sourceMinLength, targetArity); + } + return Ternary.False; + } + if (!targetHasRestElement && (sourceRestFlag || targetArity < sourceArity)) { + if (reportErrors) { + if (sourceMinLength < targetMinLength) { + reportError(Diagnostics.Target_requires_0_element_s_but_source_may_have_fewer, targetMinLength); + } + else { + reportError(Diagnostics.Target_allows_only_0_element_s_but_source_may_have_more, targetArity); + } + } + return Ternary.False; + } + const sourceTypeArguments = getTypeArguments(source); + const targetTypeArguments = getTypeArguments(target); + const targetStartCount = getStartElementCount(target.target, ElementFlags.NonRest); + const targetEndCount = getEndElementCount(target.target, ElementFlags.NonRest); + let canExcludeDiscriminants = !!excludedProperties; + for (let sourcePosition = 0; sourcePosition < sourceArity; sourcePosition++) { + const sourceFlags = isTupleType(source) ? source.target.elementFlags[sourcePosition] : ElementFlags.Rest; + const sourcePositionFromEnd = sourceArity - 1 - sourcePosition; + + const targetPosition = targetHasRestElement && sourcePosition >= targetStartCount + ? targetArity - 1 - Math.min(sourcePositionFromEnd, targetEndCount) + : sourcePosition; + + const targetFlags = target.target.elementFlags[targetPosition]; + + if (targetFlags & ElementFlags.Variadic && !(sourceFlags & ElementFlags.Variadic)) { + if (reportErrors) { + reportError(Diagnostics.Source_provides_no_match_for_variadic_element_at_position_0_in_target, targetPosition); + } + return Ternary.False; + } + if (sourceFlags & ElementFlags.Variadic && !(targetFlags & ElementFlags.Variable)) { + if (reportErrors) { + reportError(Diagnostics.Variadic_element_at_position_0_in_source_does_not_match_element_at_position_1_in_target, sourcePosition, targetPosition); + } + return Ternary.False; + } + if (targetFlags & ElementFlags.Required && !(sourceFlags & ElementFlags.Required)) { + if (reportErrors) { + reportError(Diagnostics.Source_provides_no_match_for_required_element_at_position_0_in_target, targetPosition); + } + return Ternary.False; + } + // We can only exclude discriminant properties if we have not yet encountered a variable-length element. + if (canExcludeDiscriminants) { + if (sourceFlags & ElementFlags.Variable || targetFlags & ElementFlags.Variable) { + canExcludeDiscriminants = false; + } + if (canExcludeDiscriminants && excludedProperties?.has(("" + sourcePosition) as __String)) { + continue; + } + } + + const sourceType = removeMissingType(sourceTypeArguments[sourcePosition], !!(sourceFlags & targetFlags & ElementFlags.Optional)); + const targetType = targetTypeArguments[targetPosition]; + + const targetCheckType = sourceFlags & ElementFlags.Variadic && targetFlags & ElementFlags.Rest ? createArrayType(targetType) : + removeMissingType(targetType, !!(targetFlags & ElementFlags.Optional)); + const related = isRelatedTo(sourceType, targetCheckType, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + if (reportErrors && (targetArity > 1 || sourceArity > 1)) { + if (targetHasRestElement && sourcePosition >= targetStartCount && sourcePositionFromEnd >= targetEndCount && targetStartCount !== sourceArity - targetEndCount - 1) { + reportIncompatibleError(Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target, targetStartCount, sourceArity - targetEndCount - 1, targetPosition); + } + else { + reportIncompatibleError(Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target, sourcePosition, targetPosition); + } + } + return Ternary.False; + } + result &= related; + } + return result; + } + if (target.target.combinedFlags & ElementFlags.Variable) { + return Ternary.False; + } + } + const requireOptionalProperties = (relation === subtypeRelation || relation === strictSubtypeRelation) && !isObjectLiteralType(source) && !isEmptyArrayLiteralType(source) && !isTupleType(source); + const unmatchedProperty = getUnmatchedProperty(source, target, requireOptionalProperties, /*matchDiscriminantProperties*/ false); + if (unmatchedProperty) { + if (reportErrors && shouldReportUnmatchedPropertyError(source, target)) { + reportUnmatchedProperty(source, target, unmatchedProperty, requireOptionalProperties); + } + return Ternary.False; + } + if (isObjectLiteralType(target)) { + for (const sourceProp of excludeProperties(getPropertiesOfType(source), excludedProperties)) { + if (!getPropertyOfObjectType(target, sourceProp.escapedName)) { + const sourceType = getTypeOfSymbol(sourceProp); + if (!(sourceType.flags & TypeFlags.Undefined)) { + if (reportErrors) { + reportError(Diagnostics.Property_0_does_not_exist_on_type_1, symbolToString(sourceProp), typeToString(target)); + } + return Ternary.False; + } + } + } + } + // We only call this for union target types when we're attempting to do excess property checking - in those cases, we want to get _all possible props_ + // from the target union, across all members + const properties = getPropertiesOfType(target); + const numericNamesOnly = isTupleType(source) && isTupleType(target); + for (const targetProp of excludeProperties(properties, excludedProperties)) { + const name = targetProp.escapedName; + if (!(targetProp.flags & SymbolFlags.Prototype) && (!numericNamesOnly || isNumericLiteralName(name) || name === "length") && (!optionalsOnly || targetProp.flags & SymbolFlags.Optional)) { + const sourceProp = getPropertyOfType(source, name); + if (sourceProp && sourceProp !== targetProp) { + const related = propertyRelatedTo(source, target, sourceProp, targetProp, getNonMissingTypeOfSymbol, reportErrors, intersectionState, relation === comparableRelation); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + } + return result; + } + + function propertiesIdenticalTo(source: Type, target: Type, excludedProperties: Set<__String> | undefined): Ternary { + if (!(source.flags & TypeFlags.Object && target.flags & TypeFlags.Object)) { + return Ternary.False; + } + const sourceProperties = excludeProperties(getPropertiesOfObjectType(source), excludedProperties); + const targetProperties = excludeProperties(getPropertiesOfObjectType(target), excludedProperties); + if (sourceProperties.length !== targetProperties.length) { + return Ternary.False; + } + let result = Ternary.True; + for (const sourceProp of sourceProperties) { + const targetProp = getPropertyOfObjectType(target, sourceProp.escapedName); + if (!targetProp) { + return Ternary.False; + } + const related = compareProperties(sourceProp, targetProp, isRelatedTo); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function signaturesRelatedTo(source: Type, target: Type, kind: SignatureKind, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + if (relation === identityRelation) { + return signaturesIdenticalTo(source, target, kind); + } + if (target === anyFunctionType || source === anyFunctionType) { + return Ternary.True; + } + + const sourceIsJSConstructor = source.symbol && isJSConstructor(source.symbol.valueDeclaration); + const targetIsJSConstructor = target.symbol && isJSConstructor(target.symbol.valueDeclaration); + + const sourceSignatures = getSignaturesOfType( + source, + (sourceIsJSConstructor && kind === SignatureKind.Construct) ? + SignatureKind.Call : kind, + ); + const targetSignatures = getSignaturesOfType( + target, + (targetIsJSConstructor && kind === SignatureKind.Construct) ? + SignatureKind.Call : kind, + ); + + if (kind === SignatureKind.Construct && sourceSignatures.length && targetSignatures.length) { + const sourceIsAbstract = !!(sourceSignatures[0].flags & SignatureFlags.Abstract); + const targetIsAbstract = !!(targetSignatures[0].flags & SignatureFlags.Abstract); + if (sourceIsAbstract && !targetIsAbstract) { + // An abstract constructor type is not assignable to a non-abstract constructor type + // as it would otherwise be possible to new an abstract class. Note that the assignability + // check we perform for an extends clause excludes construct signatures from the target, + // so this check never proceeds. + if (reportErrors) { + reportError(Diagnostics.Cannot_assign_an_abstract_constructor_type_to_a_non_abstract_constructor_type); + } + return Ternary.False; + } + if (!constructorVisibilitiesAreCompatible(sourceSignatures[0], targetSignatures[0], reportErrors)) { + return Ternary.False; + } + } + + let result = Ternary.True; + const incompatibleReporter = kind === SignatureKind.Construct ? reportIncompatibleConstructSignatureReturn : reportIncompatibleCallSignatureReturn; + const sourceObjectFlags = getObjectFlags(source); + const targetObjectFlags = getObjectFlags(target); + if ( + sourceObjectFlags & ObjectFlags.Instantiated && targetObjectFlags & ObjectFlags.Instantiated && source.symbol === target.symbol || + sourceObjectFlags & ObjectFlags.Reference && targetObjectFlags & ObjectFlags.Reference && (source as TypeReference).target === (target as TypeReference).target + ) { + // We have instantiations of the same anonymous type (which typically will be the type of a + // method). Simply do a pairwise comparison of the signatures in the two signature lists instead + // of the much more expensive N * M comparison matrix we explore below. We erase type parameters + // as they are known to always be the same. + Debug.assertEqual(sourceSignatures.length, targetSignatures.length); + for (let i = 0; i < targetSignatures.length; i++) { + const related = signatureRelatedTo(sourceSignatures[i], targetSignatures[i], /*erase*/ true, reportErrors, intersectionState, incompatibleReporter(sourceSignatures[i], targetSignatures[i])); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + else if (sourceSignatures.length === 1 && targetSignatures.length === 1) { + // For simple functions (functions with a single signature) we only erase type parameters for + // the comparable relation. Otherwise, if the source signature is generic, we instantiate it + // in the context of the target signature before checking the relationship. Ideally we'd do + // this regardless of the number of signatures, but the potential costs are prohibitive due + // to the quadratic nature of the logic below. + const eraseGenerics = relation === comparableRelation; + const sourceSignature = first(sourceSignatures); + const targetSignature = first(targetSignatures); + result = signatureRelatedTo(sourceSignature, targetSignature, eraseGenerics, reportErrors, intersectionState, incompatibleReporter(sourceSignature, targetSignature)); + if ( + !result && reportErrors && kind === SignatureKind.Construct && (sourceObjectFlags & targetObjectFlags) && + (targetSignature.declaration?.kind === SyntaxKind.Constructor || sourceSignature.declaration?.kind === SyntaxKind.Constructor) + ) { + const constructSignatureToString = (signature: Signature) => signatureToString(signature, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrowStyleSignature, kind); + reportError(Diagnostics.Type_0_is_not_assignable_to_type_1, constructSignatureToString(sourceSignature), constructSignatureToString(targetSignature)); + reportError(Diagnostics.Types_of_construct_signatures_are_incompatible); + return result; + } + } + else { + outer: + for (const t of targetSignatures) { + const saveErrorInfo = captureErrorCalculationState(); + // Only elaborate errors from the first failure + let shouldElaborateErrors = reportErrors; + for (const s of sourceSignatures) { + const related = signatureRelatedTo(s, t, /*erase*/ true, shouldElaborateErrors, intersectionState, incompatibleReporter(s, t)); + if (related) { + result &= related; + resetErrorInfo(saveErrorInfo); + continue outer; + } + shouldElaborateErrors = false; + } + if (shouldElaborateErrors) { + reportError(Diagnostics.Type_0_provides_no_match_for_the_signature_1, typeToString(source), signatureToString(t, /*enclosingDeclaration*/ undefined, /*flags*/ undefined, kind)); + } + return Ternary.False; + } + } + return result; + } + + function shouldReportUnmatchedPropertyError(source: Type, target: Type): boolean { + const typeCallSignatures = getSignaturesOfStructuredType(source, SignatureKind.Call); + const typeConstructSignatures = getSignaturesOfStructuredType(source, SignatureKind.Construct); + const typeProperties = getPropertiesOfObjectType(source); + if ((typeCallSignatures.length || typeConstructSignatures.length) && !typeProperties.length) { + if ( + (getSignaturesOfType(target, SignatureKind.Call).length && typeCallSignatures.length) || + (getSignaturesOfType(target, SignatureKind.Construct).length && typeConstructSignatures.length) + ) { + return true; // target has similar signature kinds to source, still focus on the unmatched property + } + return false; + } + return true; + } + + function reportIncompatibleCallSignatureReturn(siga: Signature, sigb: Signature) { + if (siga.parameters.length === 0 && sigb.parameters.length === 0) { + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target)); + } + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target)); + } + + function reportIncompatibleConstructSignatureReturn(siga: Signature, sigb: Signature) { + if (siga.parameters.length === 0 && sigb.parameters.length === 0) { + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target)); + } + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target)); + } + + /** + * See signatureAssignableTo, compareSignaturesIdentical + */ + function signatureRelatedTo(source: Signature, target: Signature, erase: boolean, reportErrors: boolean, intersectionState: IntersectionState, incompatibleReporter: (source: Type, target: Type) => void): Ternary { + const checkMode = relation === subtypeRelation ? SignatureCheckMode.StrictTopSignature : + relation === strictSubtypeRelation ? SignatureCheckMode.StrictTopSignature | SignatureCheckMode.StrictArity : + SignatureCheckMode.None; + return compareSignaturesRelated(erase ? getErasedSignature(source) : source, erase ? getErasedSignature(target) : target, checkMode, reportErrors, reportError, incompatibleReporter, isRelatedToWorker, reportUnreliableMapper); + function isRelatedToWorker(source: Type, target: Type, reportErrors?: boolean) { + return isRelatedTo(source, target, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + } + + function signaturesIdenticalTo(source: Type, target: Type, kind: SignatureKind): Ternary { + const sourceSignatures = getSignaturesOfType(source, kind); + const targetSignatures = getSignaturesOfType(target, kind); + if (sourceSignatures.length !== targetSignatures.length) { + return Ternary.False; + } + let result = Ternary.True; + for (let i = 0; i < sourceSignatures.length; i++) { + const related = compareSignaturesIdentical(sourceSignatures[i], targetSignatures[i], /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false, isRelatedTo); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function membersRelatedToIndexInfo(source: Type, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + let result = Ternary.True; + const keyType = targetInfo.keyType; + const props = source.flags & TypeFlags.Intersection ? getPropertiesOfUnionOrIntersectionType(source as IntersectionType) : getPropertiesOfObjectType(source); + for (const prop of props) { + // Skip over ignored JSX and symbol-named members + if (isIgnoredJsxProperty(source, prop)) { + continue; + } + if (isApplicableIndexType(getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique), keyType)) { + const propType = getNonMissingTypeOfSymbol(prop); + const type = exactOptionalPropertyTypes || propType.flags & TypeFlags.Undefined || keyType === numberType || !(prop.flags & SymbolFlags.Optional) + ? propType + : getTypeWithFacts(propType, TypeFacts.NEUndefined); + const related = isRelatedTo(type, targetInfo.type, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + if (reportErrors) { + reportError(Diagnostics.Property_0_is_incompatible_with_index_signature, symbolToString(prop)); + } + return Ternary.False; + } + result &= related; + } + } + for (const info of getIndexInfosOfType(source)) { + if (isApplicableIndexType(info.keyType, keyType)) { + const related = indexInfoRelatedTo(info, targetInfo, reportErrors, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + return result; + } + + function indexInfoRelatedTo(sourceInfo: IndexInfo, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState) { + const related = isRelatedTo(sourceInfo.type, targetInfo.type, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related && reportErrors) { + if (sourceInfo.keyType === targetInfo.keyType) { + reportError(Diagnostics._0_index_signatures_are_incompatible, typeToString(sourceInfo.keyType)); + } + else { + reportError(Diagnostics._0_and_1_index_signatures_are_incompatible, typeToString(sourceInfo.keyType), typeToString(targetInfo.keyType)); + } + } + return related; + } + + function indexSignaturesRelatedTo(source: Type, target: Type, sourceIsPrimitive: boolean, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + if (relation === identityRelation) { + return indexSignaturesIdenticalTo(source, target); + } + const indexInfos = getIndexInfosOfType(target); + const targetHasStringIndex = some(indexInfos, info => info.keyType === stringType); + let result = Ternary.True; + for (const targetInfo of indexInfos) { + const related = relation !== strictSubtypeRelation && !sourceIsPrimitive && targetHasStringIndex && targetInfo.type.flags & TypeFlags.Any ? Ternary.True : + isGenericMappedType(source) && targetHasStringIndex ? isRelatedTo(getTemplateTypeFromMappedType(source), targetInfo.type, RecursionFlags.Both, reportErrors) : + typeRelatedToIndexInfo(source, targetInfo, reportErrors, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function typeRelatedToIndexInfo(source: Type, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const sourceInfo = getApplicableIndexInfo(source, targetInfo.keyType); + if (sourceInfo) { + return indexInfoRelatedTo(sourceInfo, targetInfo, reportErrors, intersectionState); + } + // Intersection constituents are never considered to have an inferred index signature. Also, in the strict subtype relation, + // only fresh object literals are considered to have inferred index signatures. This ensures { [x: string]: xxx } <: {} but + // not vice-versa. Without this rule, those types would be mutual strict subtypes. + if (!(intersectionState & IntersectionState.Source) && (relation !== strictSubtypeRelation || getObjectFlags(source) & ObjectFlags.FreshLiteral) && isObjectTypeWithInferableIndex(source)) { + return membersRelatedToIndexInfo(source, targetInfo, reportErrors, intersectionState); + } + if (reportErrors) { + reportError(Diagnostics.Index_signature_for_type_0_is_missing_in_type_1, typeToString(targetInfo.keyType), typeToString(source)); + } + return Ternary.False; + } + + function indexSignaturesIdenticalTo(source: Type, target: Type): Ternary { + const sourceInfos = getIndexInfosOfType(source); + const targetInfos = getIndexInfosOfType(target); + if (sourceInfos.length !== targetInfos.length) { + return Ternary.False; + } + for (const targetInfo of targetInfos) { + const sourceInfo = getIndexInfoOfType(source, targetInfo.keyType); + if (!(sourceInfo && isRelatedTo(sourceInfo.type, targetInfo.type, RecursionFlags.Both) && sourceInfo.isReadonly === targetInfo.isReadonly)) { + return Ternary.False; + } + } + return Ternary.True; + } + + function constructorVisibilitiesAreCompatible(sourceSignature: Signature, targetSignature: Signature, reportErrors: boolean) { + if (!sourceSignature.declaration || !targetSignature.declaration) { + return true; + } + + const sourceAccessibility = getSelectedEffectiveModifierFlags(sourceSignature.declaration, ModifierFlags.NonPublicAccessibilityModifier); + const targetAccessibility = getSelectedEffectiveModifierFlags(targetSignature.declaration, ModifierFlags.NonPublicAccessibilityModifier); + + // A public, protected and private signature is assignable to a private signature. + if (targetAccessibility === ModifierFlags.Private) { + return true; + } + + // A public and protected signature is assignable to a protected signature. + if (targetAccessibility === ModifierFlags.Protected && sourceAccessibility !== ModifierFlags.Private) { + return true; + } + + // Only a public signature is assignable to public signature. + if (targetAccessibility !== ModifierFlags.Protected && !sourceAccessibility) { + return true; + } + + if (reportErrors) { + reportError(Diagnostics.Cannot_assign_a_0_constructor_type_to_a_1_constructor_type, visibilityToString(sourceAccessibility), visibilityToString(targetAccessibility)); + } + + return false; + } + } + + function typeCouldHaveTopLevelSingletonTypes(type: Type): boolean { + // Okay, yes, 'boolean' is a union of 'true | false', but that's not useful + // in error reporting scenarios. If you need to use this function but that detail matters, + // feel free to add a flag. + if (type.flags & TypeFlags.Boolean) { + return false; + } + + if (type.flags & TypeFlags.UnionOrIntersection) { + return !!forEach((type as IntersectionType).types, typeCouldHaveTopLevelSingletonTypes); + } + + if (type.flags & TypeFlags.Instantiable) { + const constraint = getConstraintOfType(type); + if (constraint && constraint !== type) { + return typeCouldHaveTopLevelSingletonTypes(constraint); + } + } + + return isUnitType(type) || !!(type.flags & TypeFlags.TemplateLiteral) || !!(type.flags & TypeFlags.StringMapping); + } + + function getExactOptionalUnassignableProperties(source: Type, target: Type) { + if (isTupleType(source) && isTupleType(target)) return emptyArray; + return getPropertiesOfType(target) + .filter(targetProp => isExactOptionalPropertyMismatch(getTypeOfPropertyOfType(source, targetProp.escapedName), getTypeOfSymbol(targetProp))); + } + + function isExactOptionalPropertyMismatch(source: Type | undefined, target: Type | undefined) { + return !!source && !!target && maybeTypeOfKind(source, TypeFlags.Undefined) && !!containsMissingType(target); + } + + function getExactOptionalProperties(type: Type) { + return getPropertiesOfType(type).filter(targetProp => containsMissingType(getTypeOfSymbol(targetProp))); + } + + function getBestMatchingType(source: Type, target: UnionOrIntersectionType, isRelatedTo = compareTypesAssignable) { + return findMatchingDiscriminantType(source, target, isRelatedTo) || + findMatchingTypeReferenceOrTypeAliasReference(source, target) || + findBestTypeForObjectLiteral(source, target) || + findBestTypeForInvokable(source, target) || + findMostOverlappyType(source, target); + } + + function discriminateTypeByDiscriminableItems(target: UnionType, discriminators: (readonly [() => Type, __String])[], related: (source: Type, target: Type) => boolean | Ternary) { + const types = target.types; + const include: Ternary[] = types.map(t => t.flags & TypeFlags.Primitive ? Ternary.False : Ternary.True); + for (const [getDiscriminatingType, propertyName] of discriminators) { + // If the remaining target types include at least one with a matching discriminant, eliminate those that + // have non-matching discriminants. This ensures that we ignore erroneous discriminators and gradually + // refine the target set without eliminating every constituent (which would lead to `never`). + let matched = false; + for (let i = 0; i < types.length; i++) { + if (include[i]) { + const targetType = getTypeOfPropertyOrIndexSignatureOfType(types[i], propertyName); + if (targetType && related(getDiscriminatingType(), targetType)) { + matched = true; + } + else { + include[i] = Ternary.Maybe; + } + } + } + // Turn each Ternary.Maybe into Ternary.False if there was a match. Otherwise, revert to Ternary.True. + for (let i = 0; i < types.length; i++) { + if (include[i] === Ternary.Maybe) { + include[i] = matched ? Ternary.False : Ternary.True; + } + } + } + const filtered = contains(include, Ternary.False) ? getUnionType(types.filter((_, i) => include[i]), UnionReduction.None) : target; + return filtered.flags & TypeFlags.Never ? target : filtered; + } + + /** + * A type is 'weak' if it is an object type with at least one optional property + * and no required properties, call/construct signatures or index signatures + */ + function isWeakType(type: Type): boolean { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + return resolved.callSignatures.length === 0 && resolved.constructSignatures.length === 0 && resolved.indexInfos.length === 0 && + resolved.properties.length > 0 && every(resolved.properties, p => !!(p.flags & SymbolFlags.Optional)); + } + if (type.flags & TypeFlags.Substitution) { + return isWeakType((type as SubstitutionType).baseType); + } + if (type.flags & TypeFlags.Intersection) { + return every((type as IntersectionType).types, isWeakType); + } + return false; + } + + function hasCommonProperties(source: Type, target: Type, isComparingJsxAttributes: boolean) { + for (const prop of getPropertiesOfType(source)) { + if (isKnownProperty(target, prop.escapedName, isComparingJsxAttributes)) { + return true; + } + } + return false; + } + + function getVariances(type: GenericType): VarianceFlags[] { + // Arrays and tuples are known to be covariant, no need to spend time computing this. + return type === globalArrayType || type === globalReadonlyArrayType || type.objectFlags & ObjectFlags.Tuple ? + arrayVariances : + getVariancesWorker(type.symbol, type.typeParameters); + } + + function getAliasVariances(symbol: Symbol) { + return getVariancesWorker(symbol, getSymbolLinks(symbol).typeParameters); + } + + // Return an array containing the variance of each type parameter. The variance is effectively + // a digest of the type comparisons that occur for each type argument when instantiations of the + // generic type are structurally compared. We infer the variance information by comparing + // instantiations of the generic type for type arguments with known relations. The function + // returns the emptyArray singleton when invoked recursively for the given generic type. + function getVariancesWorker(symbol: Symbol, typeParameters: readonly TypeParameter[] = emptyArray): VarianceFlags[] { + const links = getSymbolLinks(symbol); + if (!links.variances) { + tracing?.push(tracing.Phase.CheckTypes, "getVariancesWorker", { arity: typeParameters.length, id: getTypeId(getDeclaredTypeOfSymbol(symbol)) }); + const oldVarianceComputation = inVarianceComputation; + const saveResolutionStart = resolutionStart; + if (!inVarianceComputation) { + inVarianceComputation = true; + resolutionStart = resolutionTargets.length; + } + links.variances = emptyArray; + const variances = []; + for (const tp of typeParameters) { + const modifiers = getTypeParameterModifiers(tp); + let variance = modifiers & ModifierFlags.Out ? + modifiers & ModifierFlags.In ? VarianceFlags.Invariant : VarianceFlags.Covariant : + modifiers & ModifierFlags.In ? VarianceFlags.Contravariant : undefined; + if (variance === undefined) { + let unmeasurable = false; + let unreliable = false; + const oldHandler = outofbandVarianceMarkerHandler; + outofbandVarianceMarkerHandler = onlyUnreliable => onlyUnreliable ? unreliable = true : unmeasurable = true; + // We first compare instantiations where the type parameter is replaced with + // marker types that have a known subtype relationship. From this we can infer + // invariance, covariance, contravariance or bivariance. + const typeWithSuper = createMarkerType(symbol, tp, markerSuperType); + const typeWithSub = createMarkerType(symbol, tp, markerSubType); + variance = (isTypeAssignableTo(typeWithSub, typeWithSuper) ? VarianceFlags.Covariant : 0) | + (isTypeAssignableTo(typeWithSuper, typeWithSub) ? VarianceFlags.Contravariant : 0); + // If the instantiations appear to be related bivariantly it may be because the + // type parameter is independent (i.e. it isn't witnessed anywhere in the generic + // type). To determine this we compare instantiations where the type parameter is + // replaced with marker types that are known to be unrelated. + if (variance === VarianceFlags.Bivariant && isTypeAssignableTo(createMarkerType(symbol, tp, markerOtherType), typeWithSuper)) { + variance = VarianceFlags.Independent; + } + outofbandVarianceMarkerHandler = oldHandler; + if (unmeasurable || unreliable) { + if (unmeasurable) { + variance |= VarianceFlags.Unmeasurable; + } + if (unreliable) { + variance |= VarianceFlags.Unreliable; + } + } + } + variances.push(variance); + } + if (!oldVarianceComputation) { + inVarianceComputation = false; + resolutionStart = saveResolutionStart; + } + links.variances = variances; + tracing?.pop({ variances: variances.map(Debug.formatVariance) }); + } + return links.variances; + } + + function createMarkerType(symbol: Symbol, source: TypeParameter, target: Type) { + const mapper = makeUnaryTypeMapper(source, target); + const type = getDeclaredTypeOfSymbol(symbol); + if (isErrorType(type)) { + return type; + } + const result = symbol.flags & SymbolFlags.TypeAlias ? + getTypeAliasInstantiation(symbol, instantiateTypes(getSymbolLinks(symbol).typeParameters!, mapper)) : + createTypeReference(type as GenericType, instantiateTypes((type as GenericType).typeParameters, mapper)); + markerTypes.add(getTypeId(result)); + return result; + } + + function isMarkerType(type: Type) { + return markerTypes.has(getTypeId(type)); + } + + function getTypeParameterModifiers(tp: TypeParameter): ModifierFlags { + return reduceLeft(tp.symbol?.declarations, (modifiers, d) => modifiers | getEffectiveModifierFlags(d), ModifierFlags.None) & (ModifierFlags.In | ModifierFlags.Out | ModifierFlags.Const); + } + + // Return true if the given type reference has a 'void' type argument for a covariant type parameter. + // See comment at call in recursiveTypeRelatedTo for when this case matters. + function hasCovariantVoidArgument(typeArguments: readonly Type[], variances: VarianceFlags[]): boolean { + for (let i = 0; i < variances.length; i++) { + if ((variances[i] & VarianceFlags.VarianceMask) === VarianceFlags.Covariant && typeArguments[i].flags & TypeFlags.Void) { + return true; + } + } + return false; + } + + function isUnconstrainedTypeParameter(type: Type) { + return type.flags & TypeFlags.TypeParameter && !getConstraintOfTypeParameter(type as TypeParameter); + } + + function isNonDeferredTypeReference(type: Type): type is TypeReference { + return !!(getObjectFlags(type) & ObjectFlags.Reference) && !(type as TypeReference).node; + } + + function isTypeReferenceWithGenericArguments(type: Type): boolean { + return isNonDeferredTypeReference(type) && some(getTypeArguments(type), t => !!(t.flags & TypeFlags.TypeParameter) || isTypeReferenceWithGenericArguments(t)); + } + + function getGenericTypeReferenceRelationKey(source: TypeReference, target: TypeReference, postFix: string, ignoreConstraints: boolean) { + const typeParameters: Type[] = []; + let constraintMarker = ""; + const sourceId = getTypeReferenceId(source, 0); + const targetId = getTypeReferenceId(target, 0); + return `${constraintMarker}${sourceId},${targetId}${postFix}`; + // getTypeReferenceId(A) returns "111=0-12=1" + // where A.id=111 and number.id=12 + function getTypeReferenceId(type: TypeReference, depth = 0) { + let result = "" + type.target.id; + for (const t of getTypeArguments(type)) { + if (t.flags & TypeFlags.TypeParameter) { + if (ignoreConstraints || isUnconstrainedTypeParameter(t)) { + let index = typeParameters.indexOf(t); + if (index < 0) { + index = typeParameters.length; + typeParameters.push(t); + } + result += "=" + index; + continue; + } + // We mark type references that reference constrained type parameters such that we know to obtain + // and look for a "broadest equivalent key" in the cache. + constraintMarker = "*"; + } + else if (depth < 4 && isTypeReferenceWithGenericArguments(t)) { + result += "<" + getTypeReferenceId(t as TypeReference, depth + 1) + ">"; + continue; + } + result += "-" + t.id; + } + return result; + } + } + + /** + * To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters. + * For other cases, the types ids are used. + */ + function getRelationKey(source: Type, target: Type, intersectionState: IntersectionState, relation: Map, ignoreConstraints: boolean) { + if (relation === identityRelation && source.id > target.id) { + const temp = source; + source = target; + target = temp; + } + const postFix = intersectionState ? ":" + intersectionState : ""; + return isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target) ? + getGenericTypeReferenceRelationKey(source as TypeReference, target as TypeReference, postFix, ignoreConstraints) : + `${source.id},${target.id}${postFix}`; + } + + // Invoke the callback for each underlying property symbol of the given symbol and return the first + // value that isn't undefined. + function forEachProperty(prop: Symbol, callback: (p: Symbol) => T): T | undefined { + if (getCheckFlags(prop) & CheckFlags.Synthetic) { + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.Synthetic + for (const t of (prop as TransientSymbol).links.containingType!.types) { + const p = getPropertyOfType(t, prop.escapedName); + const result = p && forEachProperty(p, callback); + if (result) { + return result; + } + } + return undefined; + } + return callback(prop); + } + + // Return the declaring class type of a property or undefined if property not declared in class + function getDeclaringClass(prop: Symbol) { + return prop.parent && prop.parent.flags & SymbolFlags.Class ? getDeclaredTypeOfSymbol(getParentOfSymbol(prop)!) as InterfaceType : undefined; + } + + // Return the inherited type of the given property or undefined if property doesn't exist in a base class. + function getTypeOfPropertyInBaseClass(property: Symbol) { + const classType = getDeclaringClass(property); + const baseClassType = classType && getBaseTypes(classType)[0]; + return baseClassType && getTypeOfPropertyOfType(baseClassType, property.escapedName); + } + + // Return true if some underlying source property is declared in a class that derives + // from the given base class. + function isPropertyInClassDerivedFrom(prop: Symbol, baseClass: Type | undefined) { + return forEachProperty(prop, sp => { + const sourceClass = getDeclaringClass(sp); + return sourceClass ? hasBaseType(sourceClass, baseClass) : false; + }); + } + + // Return true if source property is a valid override of protected parts of target property. + function isValidOverrideOf(sourceProp: Symbol, targetProp: Symbol) { + return !forEachProperty(targetProp, tp => + getDeclarationModifierFlagsFromSymbol(tp) & ModifierFlags.Protected ? + !isPropertyInClassDerivedFrom(sourceProp, getDeclaringClass(tp)) : false); + } + + // Return true if the given class derives from each of the declaring classes of the protected + // constituents of the given property. + function isClassDerivedFromDeclaringClasses(checkClass: T, prop: Symbol, writing: boolean) { + return forEachProperty(prop, p => + getDeclarationModifierFlagsFromSymbol(p, writing) & ModifierFlags.Protected ? + !hasBaseType(checkClass, getDeclaringClass(p)) : false) ? undefined : checkClass; + } + + // Return true if the given type is deeply nested. We consider this to be the case when the given stack contains + // maxDepth or more occurrences of types with the same recursion identity as the given type. The recursion identity + // provides a shared identity for type instantiations that repeat in some (possibly infinite) pattern. For example, + // in `type Deep = { next: Deep> }`, repeatedly referencing the `next` property leads to an infinite + // sequence of ever deeper instantiations with the same recursion identity (in this case the symbol associated with + // the object type literal). + // A homomorphic mapped type is considered deeply nested if its target type is deeply nested, and an intersection is + // considered deeply nested if any constituent of the intersection is deeply nested. + // It is possible, though highly unlikely, for the deeply nested check to be true in a situation where a chain of + // instantiations is not infinitely expanding. Effectively, we will generate a false positive when two types are + // structurally equal to at least maxDepth levels, but unequal at some level beyond that. + function isDeeplyNestedType(type: Type, stack: Type[], depth: number, maxDepth = 3): boolean { + if (depth >= maxDepth) { + if ((getObjectFlags(type) & ObjectFlags.InstantiatedMapped) === ObjectFlags.InstantiatedMapped) { + type = getMappedTargetWithSymbol(type); + } + if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, t => isDeeplyNestedType(t, stack, depth, maxDepth)); + } + const identity = getRecursionIdentity(type); + let count = 0; + let lastTypeId = 0; + for (let i = 0; i < depth; i++) { + const t = stack[i]; + if (hasMatchingRecursionIdentity(t, identity)) { + // We only count occurrences with a higher type id than the previous occurrence, since higher + // type ids are an indicator of newer instantiations caused by recursion. + if (t.id >= lastTypeId) { + count++; + if (count >= maxDepth) { + return true; + } + } + lastTypeId = t.id; + } + } + } + return false; + } + + // Unwrap nested homomorphic mapped types and return the deepest target type that has a symbol. This better + // preserves unique type identities for mapped types applied to explicitly written object literals. For example + // in `Mapped<{ x: Mapped<{ x: Mapped<{ x: string }>}>}>`, each of the mapped type applications will have a + // unique recursion identity (that of their target object type literal) and thus avoid appearing deeply nested. + function getMappedTargetWithSymbol(type: Type) { + let target; + while ( + (getObjectFlags(type) & ObjectFlags.InstantiatedMapped) === ObjectFlags.InstantiatedMapped && + (target = getModifiersTypeFromMappedType(type as MappedType)) && + (target.symbol || target.flags & TypeFlags.Intersection && some((target as IntersectionType).types, t => !!t.symbol)) + ) { + type = target; + } + return type; + } + + function hasMatchingRecursionIdentity(type: Type, identity: object): boolean { + if ((getObjectFlags(type) & ObjectFlags.InstantiatedMapped) === ObjectFlags.InstantiatedMapped) { + type = getMappedTargetWithSymbol(type); + } + if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, t => hasMatchingRecursionIdentity(t, identity)); + } + return getRecursionIdentity(type) === identity; + } + + // The recursion identity of a type is an object identity that is shared among multiple instantiations of the type. + // We track recursion identities in order to identify deeply nested and possibly infinite type instantiations with + // the same origin. For example, when type parameters are in scope in an object type such as { x: T }, all + // instantiations of that type have the same recursion identity. The default recursion identity is the object + // identity of the type, meaning that every type is unique. Generally, types with constituents that could circularly + // reference the type have a recursion identity that differs from the object identity. + function getRecursionIdentity(type: Type): object { + // Object and array literals are known not to contain recursive references and don't need a recursion identity. + if (type.flags & TypeFlags.Object && !isObjectOrArrayLiteralType(type)) { + if (getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).node) { + // Deferred type references are tracked through their associated AST node. This gives us finer + // granularity than using their associated target because each manifest type reference has a + // unique AST node. + return (type as TypeReference).node!; + } + if (type.symbol && !(getObjectFlags(type) & ObjectFlags.Anonymous && type.symbol.flags & SymbolFlags.Class)) { + // We track object types that have a symbol by that symbol (representing the origin of the type), but + // exclude the static side of a class since it shares its symbol with the instance side. + return type.symbol; + } + if (isTupleType(type)) { + return type.target; + } + } + if (type.flags & TypeFlags.TypeParameter) { + // We use the symbol of the type parameter such that all "fresh" instantiations of that type parameter + // have the same recursion identity. + return type.symbol; + } + if (type.flags & TypeFlags.IndexedAccess) { + // Identity is the leftmost object type in a chain of indexed accesses, eg, in A[P1][P2][P3] it is A. + do { + type = (type as IndexedAccessType).objectType; + } + while (type.flags & TypeFlags.IndexedAccess); + return type; + } + if (type.flags & TypeFlags.Conditional) { + // The root object represents the origin of the conditional type + return (type as ConditionalType).root; + } + return type; + } + + function isPropertyIdenticalTo(sourceProp: Symbol, targetProp: Symbol): boolean { + return compareProperties(sourceProp, targetProp, compareTypesIdentical) !== Ternary.False; + } + + function compareProperties(sourceProp: Symbol, targetProp: Symbol, compareTypes: (source: Type, target: Type) => Ternary): Ternary { + // Two members are considered identical when + // - they are public properties with identical names, optionality, and types, + // - they are private or protected properties originating in the same declaration and having identical types + if (sourceProp === targetProp) { + return Ternary.True; + } + const sourcePropAccessibility = getDeclarationModifierFlagsFromSymbol(sourceProp) & ModifierFlags.NonPublicAccessibilityModifier; + const targetPropAccessibility = getDeclarationModifierFlagsFromSymbol(targetProp) & ModifierFlags.NonPublicAccessibilityModifier; + if (sourcePropAccessibility !== targetPropAccessibility) { + return Ternary.False; + } + if (sourcePropAccessibility) { + if (getTargetSymbol(sourceProp) !== getTargetSymbol(targetProp)) { + return Ternary.False; + } + } + else { + if ((sourceProp.flags & SymbolFlags.Optional) !== (targetProp.flags & SymbolFlags.Optional)) { + return Ternary.False; + } + } + if (isReadonlySymbol(sourceProp) !== isReadonlySymbol(targetProp)) { + return Ternary.False; + } + return compareTypes(getTypeOfSymbol(sourceProp), getTypeOfSymbol(targetProp)); + } + + function isMatchingSignature(source: Signature, target: Signature, partialMatch: boolean) { + const sourceParameterCount = getParameterCount(source); + const targetParameterCount = getParameterCount(target); + const sourceMinArgumentCount = getMinArgumentCount(source); + const targetMinArgumentCount = getMinArgumentCount(target); + const sourceHasRestParameter = hasEffectiveRestParameter(source); + const targetHasRestParameter = hasEffectiveRestParameter(target); + // A source signature matches a target signature if the two signatures have the same number of required, + // optional, and rest parameters. + if ( + sourceParameterCount === targetParameterCount && + sourceMinArgumentCount === targetMinArgumentCount && + sourceHasRestParameter === targetHasRestParameter + ) { + return true; + } + // A source signature partially matches a target signature if the target signature has no fewer required + // parameters + if (partialMatch && sourceMinArgumentCount <= targetMinArgumentCount) { + return true; + } + return false; + } + + /** + * See signatureRelatedTo, compareSignaturesIdentical + */ + function compareSignaturesIdentical(source: Signature, target: Signature, partialMatch: boolean, ignoreThisTypes: boolean, ignoreReturnTypes: boolean, compareTypes: (s: Type, t: Type) => Ternary): Ternary { + // TODO (drosen): De-duplicate code between related functions. + if (source === target) { + return Ternary.True; + } + if (!(isMatchingSignature(source, target, partialMatch))) { + return Ternary.False; + } + // Check that the two signatures have the same number of type parameters. + if (length(source.typeParameters) !== length(target.typeParameters)) { + return Ternary.False; + } + // Check that type parameter constraints and defaults match. If they do, instantiate the source + // signature with the type parameters of the target signature and continue the comparison. + if (target.typeParameters) { + const mapper = createTypeMapper(source.typeParameters!, target.typeParameters); + for (let i = 0; i < target.typeParameters.length; i++) { + const s = source.typeParameters![i]; + const t = target.typeParameters[i]; + if ( + !(s === t || compareTypes(instantiateType(getConstraintFromTypeParameter(s), mapper) || unknownType, getConstraintFromTypeParameter(t) || unknownType) && + compareTypes(instantiateType(getDefaultFromTypeParameter(s), mapper) || unknownType, getDefaultFromTypeParameter(t) || unknownType)) + ) { + return Ternary.False; + } + } + source = instantiateSignature(source, mapper, /*eraseTypeParameters*/ true); + } + let result = Ternary.True; + if (!ignoreThisTypes) { + const sourceThisType = getThisTypeOfSignature(source); + if (sourceThisType) { + const targetThisType = getThisTypeOfSignature(target); + if (targetThisType) { + const related = compareTypes(sourceThisType, targetThisType); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + } + const targetLen = getParameterCount(target); + for (let i = 0; i < targetLen; i++) { + const s = getTypeAtPosition(source, i); + const t = getTypeAtPosition(target, i); + const related = compareTypes(t, s); + if (!related) { + return Ternary.False; + } + result &= related; + } + if (!ignoreReturnTypes) { + const sourceTypePredicate = getTypePredicateOfSignature(source); + const targetTypePredicate = getTypePredicateOfSignature(target); + result &= sourceTypePredicate || targetTypePredicate ? + compareTypePredicatesIdentical(sourceTypePredicate, targetTypePredicate, compareTypes) : + compareTypes(getReturnTypeOfSignature(source), getReturnTypeOfSignature(target)); + } + return result; + } + + function compareTypePredicatesIdentical(source: TypePredicate | undefined, target: TypePredicate | undefined, compareTypes: (s: Type, t: Type) => Ternary): Ternary { + return !(source && target && typePredicateKindsMatch(source, target)) ? Ternary.False : + source.type === target.type ? Ternary.True : + source.type && target.type ? compareTypes(source.type, target.type) : + Ternary.False; + } + + function literalTypesWithSameBaseType(types: Type[]): boolean { + let commonBaseType: Type | undefined; + for (const t of types) { + if (!(t.flags & TypeFlags.Never)) { + const baseType = getBaseTypeOfLiteralType(t); + commonBaseType ??= baseType; + if (baseType === t || baseType !== commonBaseType) { + return false; + } + } + } + return true; + } + + function getCombinedTypeFlags(types: Type[]): TypeFlags { + return reduceLeft(types, (flags, t) => flags | (t.flags & TypeFlags.Union ? getCombinedTypeFlags((t as UnionType).types) : t.flags), 0 as TypeFlags); + } + + function getCommonSupertype(types: Type[]): Type { + if (types.length === 1) { + return types[0]; + } + // Remove nullable types from each of the candidates. + const primaryTypes = strictNullChecks ? sameMap(types, t => filterType(t, u => !(u.flags & TypeFlags.Nullable))) : types; + // When the candidate types are all literal types with the same base type, return a union + // of those literal types. Otherwise, return the leftmost type for which no type to the + // right is a supertype. + const superTypeOrUnion = literalTypesWithSameBaseType(primaryTypes) ? + getUnionType(primaryTypes) : + reduceLeft(primaryTypes, (s, t) => isTypeSubtypeOf(s, t) ? t : s)!; + // Add any nullable types that occurred in the candidates back to the result. + return primaryTypes === types ? superTypeOrUnion : getNullableType(superTypeOrUnion, getCombinedTypeFlags(types) & TypeFlags.Nullable); + } + + // Return the leftmost type for which no type to the right is a subtype. + function getCommonSubtype(types: Type[]) { + return reduceLeft(types, (s, t) => isTypeSubtypeOf(t, s) ? t : s)!; + } + + function isArrayType(type: Type): type is TypeReference { + return !!(getObjectFlags(type) & ObjectFlags.Reference) && ((type as TypeReference).target === globalArrayType || (type as TypeReference).target === globalReadonlyArrayType); + } + + function isReadonlyArrayType(type: Type): boolean { + return !!(getObjectFlags(type) & ObjectFlags.Reference) && (type as TypeReference).target === globalReadonlyArrayType; + } + + function isArrayOrTupleType(type: Type): type is TypeReference { + return isArrayType(type) || isTupleType(type); + } + + function isMutableArrayOrTuple(type: Type): boolean { + return isArrayType(type) && !isReadonlyArrayType(type) || isTupleType(type) && !type.target.readonly; + } + + function getElementTypeOfArrayType(type: Type): Type | undefined { + return isArrayType(type) ? getTypeArguments(type)[0] : undefined; + } + + function isArrayLikeType(type: Type): boolean { + // A type is array-like if it is a reference to the global Array or global ReadonlyArray type, + // or if it is not the undefined or null type and if it is assignable to ReadonlyArray + return isArrayType(type) || !(type.flags & TypeFlags.Nullable) && isTypeAssignableTo(type, anyReadonlyArrayType); + } + + function isMutableArrayLikeType(type: Type): boolean { + // A type is mutable-array-like if it is a reference to the global Array type, or if it is not the + // any, undefined or null type and if it is assignable to Array + return isMutableArrayOrTuple(type) || !(type.flags & (TypeFlags.Any | TypeFlags.Nullable)) && isTypeAssignableTo(type, anyArrayType); + } + + function getSingleBaseForNonAugmentingSubtype(type: Type) { + if (!(getObjectFlags(type) & ObjectFlags.Reference) || !(getObjectFlags((type as TypeReference).target) & ObjectFlags.ClassOrInterface)) { + return undefined; + } + if (getObjectFlags(type) & ObjectFlags.IdenticalBaseTypeCalculated) { + return getObjectFlags(type) & ObjectFlags.IdenticalBaseTypeExists ? (type as TypeReference).cachedEquivalentBaseType : undefined; + } + (type as TypeReference).objectFlags |= ObjectFlags.IdenticalBaseTypeCalculated; + const target = (type as TypeReference).target as InterfaceType; + if (getObjectFlags(target) & ObjectFlags.Class) { + const baseTypeNode = getBaseTypeNodeOfClass(target); + // A base type expression may circularly reference the class itself (e.g. as an argument to function call), so we only + // check for base types specified as simple qualified names. + if (baseTypeNode && baseTypeNode.expression.kind !== SyntaxKind.Identifier && baseTypeNode.expression.kind !== SyntaxKind.PropertyAccessExpression) { + return undefined; + } + } + const bases = getBaseTypes(target); + if (bases.length !== 1) { + return undefined; + } + if (getMembersOfSymbol(type.symbol).size) { + return undefined; // If the interface has any members, they may subtype members in the base, so we should do a full structural comparison + } + let instantiatedBase = !length(target.typeParameters) ? bases[0] : instantiateType(bases[0], createTypeMapper(target.typeParameters!, getTypeArguments(type as TypeReference).slice(0, target.typeParameters!.length))); + if (length(getTypeArguments(type as TypeReference)) > length(target.typeParameters)) { + instantiatedBase = getTypeWithThisArgument(instantiatedBase, last(getTypeArguments(type as TypeReference))); + } + (type as TypeReference).objectFlags |= ObjectFlags.IdenticalBaseTypeExists; + return (type as TypeReference).cachedEquivalentBaseType = instantiatedBase; + } + + function isEmptyLiteralType(type: Type): boolean { + return strictNullChecks ? type === implicitNeverType : type === undefinedWideningType; + } + + function isEmptyArrayLiteralType(type: Type): boolean { + const elementType = getElementTypeOfArrayType(type); + return !!elementType && isEmptyLiteralType(elementType); + } + + function isTupleLikeType(type: Type): boolean { + let lengthType; + return isTupleType(type) || + !!getPropertyOfType(type, "0" as __String) || + isArrayLikeType(type) && !!(lengthType = getTypeOfPropertyOfType(type, "length" as __String)) && everyType(lengthType, t => !!(t.flags & TypeFlags.NumberLiteral)); + } + + function isArrayOrTupleLikeType(type: Type): boolean { + return isArrayLikeType(type) || isTupleLikeType(type); + } + + function getTupleElementType(type: Type, index: number) { + const propType = getTypeOfPropertyOfType(type, "" + index as __String); + if (propType) { + return propType; + } + if (everyType(type, isTupleType)) { + return getTupleElementTypeOutOfStartCount(type, index, compilerOptions.noUncheckedIndexedAccess ? undefinedType : undefined); + } + return undefined; + } + + function isNeitherUnitTypeNorNever(type: Type): boolean { + return !(type.flags & (TypeFlags.Unit | TypeFlags.Never)); + } + + function isUnitType(type: Type): boolean { + return !!(type.flags & TypeFlags.Unit); + } + + function isUnitLikeType(type: Type): boolean { + // Intersections that reduce to 'never' (e.g. 'T & null' where 'T extends {}') are not unit types. + const t = getBaseConstraintOrType(type); + // Scan intersections such that tagged literal types are considered unit types. + return t.flags & TypeFlags.Intersection ? some((t as IntersectionType).types, isUnitType) : isUnitType(t); + } + + function extractUnitType(type: Type) { + return type.flags & TypeFlags.Intersection ? find((type as IntersectionType).types, isUnitType) || type : type; + } + + function isLiteralType(type: Type): boolean { + return type.flags & TypeFlags.Boolean ? true : + type.flags & TypeFlags.Union ? type.flags & TypeFlags.EnumLiteral ? true : every((type as UnionType).types, isUnitType) : + isUnitType(type); + } + + function getBaseTypeOfLiteralType(type: Type): Type { + return type.flags & TypeFlags.EnumLike ? getBaseTypeOfEnumLikeType(type as LiteralType) : + type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? stringType : + type.flags & TypeFlags.NumberLiteral ? numberType : + type.flags & TypeFlags.BigIntLiteral ? bigintType : + type.flags & TypeFlags.BooleanLiteral ? booleanType : + type.flags & TypeFlags.Union ? getBaseTypeOfLiteralTypeUnion(type as UnionType) : + type; + } + + function getBaseTypeOfLiteralTypeUnion(type: UnionType) { + const key = `B${getTypeId(type)}`; + return getCachedType(key) ?? setCachedType(key, mapType(type, getBaseTypeOfLiteralType)); + } + + // This like getBaseTypeOfLiteralType, but instead treats enum literals as strings/numbers instead + // of returning their enum base type (which depends on the types of other literals in the enum). + function getBaseTypeOfLiteralTypeForComparison(type: Type): Type { + return type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? stringType : + type.flags & (TypeFlags.NumberLiteral | TypeFlags.Enum) ? numberType : + type.flags & TypeFlags.BigIntLiteral ? bigintType : + type.flags & TypeFlags.BooleanLiteral ? booleanType : + type.flags & TypeFlags.Union ? mapType(type, getBaseTypeOfLiteralTypeForComparison) : + type; + } + + function getWidenedLiteralType(type: Type): Type { + return type.flags & TypeFlags.EnumLike && isFreshLiteralType(type) ? getBaseTypeOfEnumLikeType(type as LiteralType) : + type.flags & TypeFlags.StringLiteral && isFreshLiteralType(type) ? stringType : + type.flags & TypeFlags.NumberLiteral && isFreshLiteralType(type) ? numberType : + type.flags & TypeFlags.BigIntLiteral && isFreshLiteralType(type) ? bigintType : + type.flags & TypeFlags.BooleanLiteral && isFreshLiteralType(type) ? booleanType : + type.flags & TypeFlags.Union ? mapType(type as UnionType, getWidenedLiteralType) : + type; + } + + function getWidenedUniqueESSymbolType(type: Type): Type { + return type.flags & TypeFlags.UniqueESSymbol ? esSymbolType : + type.flags & TypeFlags.Union ? mapType(type as UnionType, getWidenedUniqueESSymbolType) : + type; + } + + function getWidenedLiteralLikeTypeForContextualType(type: Type, contextualType: Type | undefined) { + if (!isLiteralOfContextualType(type, contextualType)) { + type = getWidenedUniqueESSymbolType(getWidenedLiteralType(type)); + } + return getRegularTypeOfLiteralType(type); + } + + function getWidenedLiteralLikeTypeForContextualReturnTypeIfNeeded(type: Type | undefined, contextualSignatureReturnType: Type | undefined, isAsync: boolean) { + if (type && isUnitType(type)) { + const contextualType = !contextualSignatureReturnType ? undefined : + isAsync ? getPromisedTypeOfPromise(contextualSignatureReturnType) : + contextualSignatureReturnType; + type = getWidenedLiteralLikeTypeForContextualType(type, contextualType); + } + return type; + } + + function getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(type: Type | undefined, contextualSignatureReturnType: Type | undefined, kind: IterationTypeKind, isAsyncGenerator: boolean) { + if (type && isUnitType(type)) { + const contextualType = !contextualSignatureReturnType ? undefined : + getIterationTypeOfGeneratorFunctionReturnType(kind, contextualSignatureReturnType, isAsyncGenerator); + type = getWidenedLiteralLikeTypeForContextualType(type, contextualType); + } + return type; + } + + /** + * Check if a Type was written as a tuple type literal. + * Prefer using isTupleLikeType() unless the use of `elementTypes`/`getTypeArguments` is required. + */ + function isTupleType(type: Type): type is TupleTypeReference { + return !!(getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).target.objectFlags & ObjectFlags.Tuple); + } + + function isGenericTupleType(type: Type): type is TupleTypeReference { + return isTupleType(type) && !!(type.target.combinedFlags & ElementFlags.Variadic); + } + + function isSingleElementGenericTupleType(type: Type): type is TupleTypeReference { + return isGenericTupleType(type) && type.target.elementFlags.length === 1; + } + + function getRestTypeOfTupleType(type: TupleTypeReference) { + return getElementTypeOfSliceOfTupleType(type, type.target.fixedLength); + } + + function getTupleElementTypeOutOfStartCount(type: Type, index: number, undefinedOrMissingType: Type | undefined) { + return mapType(type, t => { + const tupleType = t as TupleTypeReference; + const restType = getRestTypeOfTupleType(tupleType); + if (!restType) { + return undefinedType; + } + if (undefinedOrMissingType && index >= getTotalFixedElementCount(tupleType.target)) { + return getUnionType([restType, undefinedOrMissingType]); + } + return restType; + }); + } + + function getRestArrayTypeOfTupleType(type: TupleTypeReference) { + const restType = getRestTypeOfTupleType(type); + return restType && createArrayType(restType); + } + + function getElementTypeOfSliceOfTupleType(type: TupleTypeReference, index: number, endSkipCount = 0, writing = false, noReductions = false) { + const length = getTypeReferenceArity(type) - endSkipCount; + if (index < length) { + const typeArguments = getTypeArguments(type); + const elementTypes: Type[] = []; + for (let i = index; i < length; i++) { + const t = typeArguments[i]; + elementTypes.push(type.target.elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t); + } + return writing ? getIntersectionType(elementTypes) : getUnionType(elementTypes, noReductions ? UnionReduction.None : UnionReduction.Literal); + } + return undefined; + } + + function isTupleTypeStructureMatching(t1: TupleTypeReference, t2: TupleTypeReference) { + return getTypeReferenceArity(t1) === getTypeReferenceArity(t2) && + every(t1.target.elementFlags, (f, i) => (f & ElementFlags.Variable) === (t2.target.elementFlags[i] & ElementFlags.Variable)); + } + + function isZeroBigInt({ value }: BigIntLiteralType) { + return value.base10Value === "0"; + } + + function removeDefinitelyFalsyTypes(type: Type): Type { + return filterType(type, t => hasTypeFacts(t, TypeFacts.Truthy)); + } + + function extractDefinitelyFalsyTypes(type: Type): Type { + return mapType(type, getDefinitelyFalsyPartOfType); + } + + function getDefinitelyFalsyPartOfType(type: Type): Type { + return type.flags & TypeFlags.String ? emptyStringType : + type.flags & TypeFlags.Number ? zeroType : + type.flags & TypeFlags.BigInt ? zeroBigIntType : + type === regularFalseType || + type === falseType || + type.flags & (TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Null | TypeFlags.AnyOrUnknown) || + type.flags & TypeFlags.StringLiteral && (type as StringLiteralType).value === "" || + type.flags & TypeFlags.NumberLiteral && (type as NumberLiteralType).value === 0 || + type.flags & TypeFlags.BigIntLiteral && isZeroBigInt(type as BigIntLiteralType) ? type : + neverType; + } + + /** + * Add undefined or null or both to a type if they are missing. + * @param type - type to add undefined and/or null to if not present + * @param flags - Either TypeFlags.Undefined or TypeFlags.Null, or both + */ + function getNullableType(type: Type, flags: TypeFlags): Type { + const missing = (flags & ~type.flags) & (TypeFlags.Undefined | TypeFlags.Null); + return missing === 0 ? type : + missing === TypeFlags.Undefined ? getUnionType([type, undefinedType]) : + missing === TypeFlags.Null ? getUnionType([type, nullType]) : + getUnionType([type, undefinedType, nullType]); + } + + function getOptionalType(type: Type, isProperty = false): Type { + Debug.assert(strictNullChecks); + const missingOrUndefined = isProperty ? undefinedOrMissingType : undefinedType; + return type === missingOrUndefined || type.flags & TypeFlags.Union && (type as UnionType).types[0] === missingOrUndefined ? type : getUnionType([type, missingOrUndefined]); + } + + function getGlobalNonNullableTypeInstantiation(type: Type) { + if (!deferredGlobalNonNullableTypeAlias) { + deferredGlobalNonNullableTypeAlias = getGlobalSymbol("NonNullable" as __String, SymbolFlags.TypeAlias, /*diagnostic*/ undefined) || unknownSymbol; + } + return deferredGlobalNonNullableTypeAlias !== unknownSymbol ? + getTypeAliasInstantiation(deferredGlobalNonNullableTypeAlias, [type]) : + getIntersectionType([type, emptyObjectType]); + } + + function getNonNullableType(type: Type): Type { + return strictNullChecks ? getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; + } + + function addOptionalTypeMarker(type: Type) { + return strictNullChecks ? getUnionType([type, optionalType]) : type; + } + + function removeOptionalTypeMarker(type: Type): Type { + return strictNullChecks ? removeType(type, optionalType) : type; + } + + function propagateOptionalTypeMarker(type: Type, node: OptionalChain, wasOptional: boolean) { + return wasOptional ? isOutermostOptionalChain(node) ? getOptionalType(type) : addOptionalTypeMarker(type) : type; + } + + function getOptionalExpressionType(exprType: Type, expression: Expression) { + return isExpressionOfOptionalChainRoot(expression) ? getNonNullableType(exprType) : + isOptionalChain(expression) ? removeOptionalTypeMarker(exprType) : + exprType; + } + + function removeMissingType(type: Type, isOptional: boolean) { + return exactOptionalPropertyTypes && isOptional ? removeType(type, missingType) : type; + } + + function containsMissingType(type: Type) { + return type === missingType || !!(type.flags & TypeFlags.Union) && (type as UnionType).types[0] === missingType; + } + + function removeMissingOrUndefinedType(type: Type): Type { + return exactOptionalPropertyTypes ? removeType(type, missingType) : getTypeWithFacts(type, TypeFacts.NEUndefined); + } + + /** + * Is source potentially coercible to target type under `==`. + * Assumes that `source` is a constituent of a union, hence + * the boolean literal flag on the LHS, but not on the RHS. + * + * This does not fully replicate the semantics of `==`. The + * intention is to catch cases that are clearly not right. + * + * Comparing (string | number) to number should not remove the + * string element. + * + * Comparing (string | number) to 1 will remove the string + * element, though this is not sound. This is a pragmatic + * choice. + * + * @see narrowTypeByEquality + * + * @param source + * @param target + */ + function isCoercibleUnderDoubleEquals(source: Type, target: Type): boolean { + return ((source.flags & (TypeFlags.Number | TypeFlags.String | TypeFlags.BooleanLiteral)) !== 0) + && ((target.flags & (TypeFlags.Number | TypeFlags.String | TypeFlags.Boolean)) !== 0); + } + + /** + * Return true if type was inferred from an object literal, written as an object type literal, or is the shape of a module + * with no call or construct signatures. + */ + function isObjectTypeWithInferableIndex(type: Type): boolean { + const objectFlags = getObjectFlags(type); + return type.flags & TypeFlags.Intersection + ? every((type as IntersectionType).types, isObjectTypeWithInferableIndex) + : !!( + type.symbol + && (type.symbol.flags & (SymbolFlags.ObjectLiteral | SymbolFlags.TypeLiteral | SymbolFlags.Enum | SymbolFlags.ValueModule)) !== 0 + && !(type.symbol.flags & SymbolFlags.Class) + && !typeHasCallOrConstructSignatures(type) + ) || !!( + objectFlags & ObjectFlags.ObjectRestType + ) || !!(objectFlags & ObjectFlags.ReverseMapped && isObjectTypeWithInferableIndex((type as ReverseMappedType).source)); + } + + function createSymbolWithType(source: Symbol, type: Type | undefined) { + const symbol = createSymbol(source.flags, source.escapedName, getCheckFlags(source) & CheckFlags.Readonly); + symbol.declarations = source.declarations; + symbol.parent = source.parent; + symbol.links.type = type; + symbol.links.target = source; + if (source.valueDeclaration) { + symbol.valueDeclaration = source.valueDeclaration; + } + const nameType = getSymbolLinks(source).nameType; + if (nameType) { + symbol.links.nameType = nameType; + } + return symbol; + } + + function transformTypeOfMembers(type: Type, f: (propertyType: Type) => Type) { + const members = createSymbolTable(); + for (const property of getPropertiesOfObjectType(type)) { + const original = getTypeOfSymbol(property); + const updated = f(original); + members.set(property.escapedName, updated === original ? property : createSymbolWithType(property, updated)); + } + return members; + } + + /** + * If the the provided object literal is subject to the excess properties check, + * create a new that is exempt. Recursively mark object literal members as exempt. + * Leave signatures alone since they are not subject to the check. + */ + function getRegularTypeOfObjectLiteral(type: Type): Type { + if (!(isObjectLiteralType(type) && getObjectFlags(type) & ObjectFlags.FreshLiteral)) { + return type; + } + const regularType = (type as FreshObjectLiteralType).regularType; + if (regularType) { + return regularType; + } + + const resolved = type as ResolvedType; + const members = transformTypeOfMembers(type, getRegularTypeOfObjectLiteral); + const regularNew = createAnonymousType(resolved.symbol, members, resolved.callSignatures, resolved.constructSignatures, resolved.indexInfos); + regularNew.flags = resolved.flags; + regularNew.objectFlags |= resolved.objectFlags & ~ObjectFlags.FreshLiteral; + (type as FreshObjectLiteralType).regularType = regularNew; + return regularNew; + } + + function createWideningContext(parent: WideningContext | undefined, propertyName: __String | undefined, siblings: Type[] | undefined): WideningContext { + return { parent, propertyName, siblings, resolvedProperties: undefined }; + } + + function getSiblingsOfContext(context: WideningContext): Type[] { + if (!context.siblings) { + const siblings: Type[] = []; + for (const type of getSiblingsOfContext(context.parent!)) { + if (isObjectLiteralType(type)) { + const prop = getPropertyOfObjectType(type, context.propertyName!); + if (prop) { + forEachType(getTypeOfSymbol(prop), t => { + siblings.push(t); + }); + } + } + } + context.siblings = siblings; + } + return context.siblings; + } + + function getPropertiesOfContext(context: WideningContext): Symbol[] { + if (!context.resolvedProperties) { + const names = new Map<__String, Symbol>(); + for (const t of getSiblingsOfContext(context)) { + if (isObjectLiteralType(t) && !(getObjectFlags(t) & ObjectFlags.ContainsSpread)) { + for (const prop of getPropertiesOfType(t)) { + names.set(prop.escapedName, prop); + } + } + } + context.resolvedProperties = arrayFrom(names.values()); + } + return context.resolvedProperties; + } + + function getWidenedProperty(prop: Symbol, context: WideningContext | undefined): Symbol { + if (!(prop.flags & SymbolFlags.Property)) { + // Since get accessors already widen their return value there is no need to + // widen accessor based properties here. + return prop; + } + const original = getTypeOfSymbol(prop); + const propContext = context && createWideningContext(context, prop.escapedName, /*siblings*/ undefined); + const widened = getWidenedTypeWithContext(original, propContext); + return widened === original ? prop : createSymbolWithType(prop, widened); + } + + function getUndefinedProperty(prop: Symbol) { + const cached = undefinedProperties.get(prop.escapedName); + if (cached) { + return cached; + } + const result = createSymbolWithType(prop, undefinedOrMissingType); + result.flags |= SymbolFlags.Optional; + undefinedProperties.set(prop.escapedName, result); + return result; + } + + function getWidenedTypeOfObjectLiteral(type: Type, context: WideningContext | undefined): Type { + const members = createSymbolTable(); + for (const prop of getPropertiesOfObjectType(type)) { + members.set(prop.escapedName, getWidenedProperty(prop, context)); + } + if (context) { + for (const prop of getPropertiesOfContext(context)) { + if (!members.has(prop.escapedName)) { + members.set(prop.escapedName, getUndefinedProperty(prop)); + } + } + } + const result = createAnonymousType(type.symbol, members, emptyArray, emptyArray, sameMap(getIndexInfosOfType(type), info => createIndexInfo(info.keyType, getWidenedType(info.type), info.isReadonly))); + result.objectFlags |= getObjectFlags(type) & (ObjectFlags.JSLiteral | ObjectFlags.NonInferrableType); // Retain js literal flag through widening + return result; + } + + function getWidenedType(type: Type) { + return getWidenedTypeWithContext(type, /*context*/ undefined); + } + + function getWidenedTypeWithContext(type: Type, context: WideningContext | undefined): Type { + if (getObjectFlags(type) & ObjectFlags.RequiresWidening) { + if (context === undefined && type.widened) { + return type.widened; + } + let result: Type | undefined; + if (type.flags & (TypeFlags.Any | TypeFlags.Nullable)) { + result = anyType; + } + else if (isObjectLiteralType(type)) { + result = getWidenedTypeOfObjectLiteral(type, context); + } + else if (type.flags & TypeFlags.Union) { + const unionContext = context || createWideningContext(/*parent*/ undefined, /*propertyName*/ undefined, (type as UnionType).types); + const widenedTypes = sameMap((type as UnionType).types, t => t.flags & TypeFlags.Nullable ? t : getWidenedTypeWithContext(t, unionContext)); + // Widening an empty object literal transitions from a highly restrictive type to + // a highly inclusive one. For that reason we perform subtype reduction here if the + // union includes empty object types (e.g. reducing {} | string to just {}). + result = getUnionType(widenedTypes, some(widenedTypes, isEmptyObjectType) ? UnionReduction.Subtype : UnionReduction.Literal); + } + else if (type.flags & TypeFlags.Intersection) { + result = getIntersectionType(sameMap((type as IntersectionType).types, getWidenedType)); + } + else if (isArrayOrTupleType(type)) { + result = createTypeReference(type.target, sameMap(getTypeArguments(type), getWidenedType)); + } + if (result && context === undefined) { + type.widened = result; + } + return result || type; + } + return type; + } + + /** + * Reports implicit any errors that occur as a result of widening 'null' and 'undefined' + * to 'any'. A call to reportWideningErrorsInType is normally accompanied by a call to + * getWidenedType. But in some cases getWidenedType is called without reporting errors + * (type argument inference is an example). + * + * The return value indicates whether an error was in fact reported. The particular circumstances + * are on a best effort basis. Currently, if the null or undefined that causes widening is inside + * an object literal property (arbitrarily deeply), this function reports an error. If no error is + * reported, reportImplicitAnyError is a suitable fallback to report a general error. + */ + function reportWideningErrorsInType(type: Type): boolean { + let errorReported = false; + if (getObjectFlags(type) & ObjectFlags.ContainsWideningType) { + if (type.flags & TypeFlags.Union) { + if (some((type as UnionType).types, isEmptyObjectType)) { + errorReported = true; + } + else { + for (const t of (type as UnionType).types) { + errorReported ||= reportWideningErrorsInType(t); + } + } + } + else if (isArrayOrTupleType(type)) { + for (const t of getTypeArguments(type)) { + errorReported ||= reportWideningErrorsInType(t); + } + } + else if (isObjectLiteralType(type)) { + for (const p of getPropertiesOfObjectType(type)) { + const t = getTypeOfSymbol(p); + if (getObjectFlags(t) & ObjectFlags.ContainsWideningType) { + errorReported = reportWideningErrorsInType(t); + if (!errorReported) { + // we need to account for property types coming from object literal type normalization in unions + const valueDeclaration = p.declarations?.find(d => d.symbol.valueDeclaration?.parent === type.symbol.valueDeclaration); + if (valueDeclaration) { + error(valueDeclaration, Diagnostics.Object_literal_s_property_0_implicitly_has_an_1_type, symbolToString(p), typeToString(getWidenedType(t))); + errorReported = true; + } + } + } + } + } + } + return errorReported; + } + + function reportImplicitAny(declaration: Declaration, type: Type, wideningKind?: WideningKind) { + const typeAsString = typeToString(getWidenedType(type)); + if (isInJSFile(declaration) && !isCheckJsEnabledForFile(getSourceFileOfNode(declaration), compilerOptions)) { + // Only report implicit any errors/suggestions in TS and ts-check JS files + return; + } + let diagnostic: DiagnosticMessage; + switch (declaration.kind) { + case SyntaxKind.BinaryExpression: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + diagnostic = noImplicitAny ? Diagnostics.Member_0_implicitly_has_an_1_type : Diagnostics.Member_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; + break; + case SyntaxKind.Parameter: + const param = declaration as ParameterDeclaration; + if (isIdentifier(param.name)) { + const originalKeywordKind = identifierToKeywordKind(param.name); + if ( + (isCallSignatureDeclaration(param.parent) || isMethodSignature(param.parent) || isFunctionTypeNode(param.parent)) && + param.parent.parameters.includes(param) && + (resolveName(param, param.name.escapedText, SymbolFlags.Type, /*nameNotFoundMessage*/ undefined, /*isUse*/ true) || + originalKeywordKind && isTypeNodeKind(originalKeywordKind)) + ) { + const newName = "arg" + param.parent.parameters.indexOf(param); + const typeName = declarationNameToString(param.name) + (param.dotDotDotToken ? "[]" : ""); + errorOrSuggestion(noImplicitAny, declaration, Diagnostics.Parameter_has_a_name_but_no_type_Did_you_mean_0_Colon_1, newName, typeName); + return; + } + } + diagnostic = (declaration as ParameterDeclaration).dotDotDotToken ? + noImplicitAny ? Diagnostics.Rest_parameter_0_implicitly_has_an_any_type : Diagnostics.Rest_parameter_0_implicitly_has_an_any_type_but_a_better_type_may_be_inferred_from_usage : + noImplicitAny ? Diagnostics.Parameter_0_implicitly_has_an_1_type : Diagnostics.Parameter_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; + break; + case SyntaxKind.BindingElement: + diagnostic = Diagnostics.Binding_element_0_implicitly_has_an_1_type; + if (!noImplicitAny) { + // Don't issue a suggestion for binding elements since the codefix doesn't yet support them. + return; + } + break; + case SyntaxKind.JSDocFunctionType: + error(declaration, Diagnostics.Function_type_which_lacks_return_type_annotation_implicitly_has_an_0_return_type, typeAsString); + return; + case SyntaxKind.JSDocSignature: + if (noImplicitAny && isJSDocOverloadTag(declaration.parent)) { + error(declaration.parent.tagName, Diagnostics.This_overload_implicitly_returns_the_type_0_because_it_lacks_a_return_type_annotation, typeAsString); + } + return; + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + if (noImplicitAny && !(declaration as NamedDeclaration).name) { + if (wideningKind === WideningKind.GeneratorYield) { + error(declaration, Diagnostics.Generator_implicitly_has_yield_type_0_because_it_does_not_yield_any_values_Consider_supplying_a_return_type_annotation, typeAsString); + } + else { + error(declaration, Diagnostics.Function_expression_which_lacks_return_type_annotation_implicitly_has_an_0_return_type, typeAsString); + } + return; + } + diagnostic = !noImplicitAny ? Diagnostics._0_implicitly_has_an_1_return_type_but_a_better_type_may_be_inferred_from_usage : + wideningKind === WideningKind.GeneratorYield ? Diagnostics._0_which_lacks_return_type_annotation_implicitly_has_an_1_yield_type : + Diagnostics._0_which_lacks_return_type_annotation_implicitly_has_an_1_return_type; + break; + case SyntaxKind.MappedType: + if (noImplicitAny) { + error(declaration, Diagnostics.Mapped_object_type_implicitly_has_an_any_template_type); + } + return; + default: + diagnostic = noImplicitAny ? Diagnostics.Variable_0_implicitly_has_an_1_type : Diagnostics.Variable_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; + } + errorOrSuggestion(noImplicitAny, declaration, diagnostic, declarationNameToString(getNameOfDeclaration(declaration)), typeAsString); + } + + function reportErrorsFromWidening(declaration: Declaration, type: Type, wideningKind?: WideningKind) { + addLazyDiagnostic(() => { + if (noImplicitAny && getObjectFlags(type) & ObjectFlags.ContainsWideningType && (!wideningKind || !getContextualSignatureForFunctionLikeDeclaration(declaration as FunctionLikeDeclaration))) { + // Report implicit any error within type if possible, otherwise report error on declaration + if (!reportWideningErrorsInType(type)) { + reportImplicitAny(declaration, type, wideningKind); + } + } + }); + } + + function applyToParameterTypes(source: Signature, target: Signature, callback: (s: Type, t: Type) => void) { + const sourceCount = getParameterCount(source); + const targetCount = getParameterCount(target); + const sourceRestType = getEffectiveRestType(source); + const targetRestType = getEffectiveRestType(target); + const targetNonRestCount = targetRestType ? targetCount - 1 : targetCount; + const paramCount = sourceRestType ? targetNonRestCount : Math.min(sourceCount, targetNonRestCount); + const sourceThisType = getThisTypeOfSignature(source); + if (sourceThisType) { + const targetThisType = getThisTypeOfSignature(target); + if (targetThisType) { + callback(sourceThisType, targetThisType); + } + } + for (let i = 0; i < paramCount; i++) { + callback(getTypeAtPosition(source, i), getTypeAtPosition(target, i)); + } + if (targetRestType) { + callback(getRestTypeAtPosition(source, paramCount, /*readonly*/ isConstTypeVariable(targetRestType) && !someType(targetRestType, isMutableArrayLikeType)), targetRestType); + } + } + + function applyToReturnTypes(source: Signature, target: Signature, callback: (s: Type, t: Type) => void) { + const targetTypePredicate = getTypePredicateOfSignature(target); + if (targetTypePredicate) { + const sourceTypePredicate = getTypePredicateOfSignature(source); + if (sourceTypePredicate && typePredicateKindsMatch(sourceTypePredicate, targetTypePredicate) && sourceTypePredicate.type && targetTypePredicate.type) { + callback(sourceTypePredicate.type, targetTypePredicate.type); + return; + } + } + const targetReturnType = getReturnTypeOfSignature(target); + if (couldContainTypeVariables(targetReturnType)) { + callback(getReturnTypeOfSignature(source), targetReturnType); + } + } + + function createInferenceContext(typeParameters: readonly TypeParameter[], signature: Signature | undefined, flags: InferenceFlags, compareTypes?: TypeComparer): InferenceContext { + return createInferenceContextWorker(typeParameters.map(createInferenceInfo), signature, flags, compareTypes || compareTypesAssignable); + } + + function cloneInferenceContext(context: T, extraFlags: InferenceFlags = 0): InferenceContext | T & undefined { + return context && createInferenceContextWorker(map(context.inferences, cloneInferenceInfo), context.signature, context.flags | extraFlags, context.compareTypes); + } + + function createInferenceContextWorker(inferences: InferenceInfo[], signature: Signature | undefined, flags: InferenceFlags, compareTypes: TypeComparer): InferenceContext { + const context: InferenceContext = { + inferences, + signature, + flags, + compareTypes, + mapper: reportUnmeasurableMapper, // initialize to a noop mapper so the context object is available, but the underlying object shape is right upon construction + nonFixingMapper: reportUnmeasurableMapper, + }; + context.mapper = makeFixingMapperForContext(context); + context.nonFixingMapper = makeNonFixingMapperForContext(context); + return context; + } + + function makeFixingMapperForContext(context: InferenceContext) { + return makeDeferredTypeMapper( + map(context.inferences, i => i.typeParameter), + map(context.inferences, (inference, i) => () => { + if (!inference.isFixed) { + // Before we commit to a particular inference (and thus lock out any further inferences), + // we infer from any intra-expression inference sites we have collected. + inferFromIntraExpressionSites(context); + clearCachedInferences(context.inferences); + inference.isFixed = true; + } + return getInferredType(context, i); + }), + ); + } + + function makeNonFixingMapperForContext(context: InferenceContext) { + return makeDeferredTypeMapper( + map(context.inferences, i => i.typeParameter), + map(context.inferences, (_, i) => () => { + return getInferredType(context, i); + }), + ); + } + + function clearCachedInferences(inferences: InferenceInfo[]) { + for (const inference of inferences) { + if (!inference.isFixed) { + inference.inferredType = undefined; + } + } + } + + function addIntraExpressionInferenceSite(context: InferenceContext, node: Expression | MethodDeclaration, type: Type) { + (context.intraExpressionInferenceSites ??= []).push({ node, type }); + } + + // We collect intra-expression inference sites within object and array literals to handle cases where + // inferred types flow between context sensitive element expressions. For example: + // + // declare function foo(arg: [(n: number) => T, (x: T) => void]): void; + // foo([_a => 0, n => n.toFixed()]); + // + // Above, both arrow functions in the tuple argument are context sensitive, thus both are omitted from the + // pass that collects inferences from the non-context sensitive parts of the arguments. In the subsequent + // pass where nothing is omitted, we need to commit to an inference for T in order to contextually type the + // parameter in the second arrow function, but we want to first infer from the return type of the first + // arrow function. This happens automatically when the arrow functions are discrete arguments (because we + // infer from each argument before processing the next), but when the arrow functions are elements of an + // object or array literal, we need to perform intra-expression inferences early. + function inferFromIntraExpressionSites(context: InferenceContext) { + if (context.intraExpressionInferenceSites) { + for (const { node, type } of context.intraExpressionInferenceSites) { + const contextualType = node.kind === SyntaxKind.MethodDeclaration ? + getContextualTypeForObjectLiteralMethod(node as MethodDeclaration, ContextFlags.NoConstraints) : + getContextualType(node, ContextFlags.NoConstraints); + if (contextualType) { + inferTypes(context.inferences, type, contextualType); + } + } + context.intraExpressionInferenceSites = undefined; + } + } + + function createInferenceInfo(typeParameter: TypeParameter): InferenceInfo { + return { + typeParameter, + candidates: undefined, + contraCandidates: undefined, + inferredType: undefined, + priority: undefined, + topLevel: true, + isFixed: false, + impliedArity: undefined, + }; + } + + function cloneInferenceInfo(inference: InferenceInfo): InferenceInfo { + return { + typeParameter: inference.typeParameter, + candidates: inference.candidates && inference.candidates.slice(), + contraCandidates: inference.contraCandidates && inference.contraCandidates.slice(), + inferredType: inference.inferredType, + priority: inference.priority, + topLevel: inference.topLevel, + isFixed: inference.isFixed, + impliedArity: inference.impliedArity, + }; + } + + function cloneInferredPartOfContext(context: InferenceContext): InferenceContext | undefined { + const inferences = filter(context.inferences, hasInferenceCandidates); + return inferences.length ? + createInferenceContextWorker(map(inferences, cloneInferenceInfo), context.signature, context.flags, context.compareTypes) : + undefined; + } + + function getMapperFromContext(context: T): TypeMapper | T & undefined { + return context && context.mapper; + } + + // Return true if the given type could possibly reference a type parameter for which + // we perform type inference (i.e. a type parameter of a generic function). We cache + // results for union and intersection types for performance reasons. + function couldContainTypeVariables(type: Type): boolean { + const objectFlags = getObjectFlags(type); + if (objectFlags & ObjectFlags.CouldContainTypeVariablesComputed) { + return !!(objectFlags & ObjectFlags.CouldContainTypeVariables); + } + const result = !!(type.flags & TypeFlags.Instantiable || + type.flags & TypeFlags.Object && !isNonGenericTopLevelType(type) && ( + objectFlags & ObjectFlags.Reference && ((type as TypeReference).node || some(getTypeArguments(type as TypeReference), couldContainTypeVariables)) || + objectFlags & ObjectFlags.SingleSignatureType && !!length((type as SingleSignatureType).outerTypeParameters) || + objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral) && type.symbol.declarations || + objectFlags & (ObjectFlags.Mapped | ObjectFlags.ReverseMapped | ObjectFlags.ObjectRestType | ObjectFlags.InstantiationExpressionType) + ) || + type.flags & TypeFlags.UnionOrIntersection && !(type.flags & TypeFlags.EnumLiteral) && !isNonGenericTopLevelType(type) && some((type as UnionOrIntersectionType).types, couldContainTypeVariables)); + if (type.flags & TypeFlags.ObjectFlagsType) { + (type as ObjectFlagsType).objectFlags |= ObjectFlags.CouldContainTypeVariablesComputed | (result ? ObjectFlags.CouldContainTypeVariables : 0); + } + return result; + } + + function isNonGenericTopLevelType(type: Type) { + if (type.aliasSymbol && !type.aliasTypeArguments) { + const declaration = getDeclarationOfKind(type.aliasSymbol, SyntaxKind.TypeAliasDeclaration); + return !!(declaration && findAncestor(declaration.parent, n => n.kind === SyntaxKind.SourceFile ? true : n.kind === SyntaxKind.ModuleDeclaration ? false : "quit")); + } + return false; + } + + function isTypeParameterAtTopLevel(type: Type, tp: TypeParameter, depth = 0): boolean { + return !!(type === tp || + type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, t => isTypeParameterAtTopLevel(t, tp, depth)) || + depth < 3 && type.flags & TypeFlags.Conditional && ( + isTypeParameterAtTopLevel(getTrueTypeFromConditionalType(type as ConditionalType), tp, depth + 1) || + isTypeParameterAtTopLevel(getFalseTypeFromConditionalType(type as ConditionalType), tp, depth + 1) + )); + } + + function isTypeParameterAtTopLevelInReturnType(signature: Signature, typeParameter: TypeParameter) { + const typePredicate = getTypePredicateOfSignature(signature); + return typePredicate ? !!typePredicate.type && isTypeParameterAtTopLevel(typePredicate.type, typeParameter) : + isTypeParameterAtTopLevel(getReturnTypeOfSignature(signature), typeParameter); + } + + /** Create an object with properties named in the string literal type. Every property has type `any` */ + function createEmptyObjectTypeFromStringLiteral(type: Type) { + const members = createSymbolTable(); + forEachType(type, t => { + if (!(t.flags & TypeFlags.StringLiteral)) { + return; + } + const name = escapeLeadingUnderscores((t as StringLiteralType).value); + const literalProp = createSymbol(SymbolFlags.Property, name); + literalProp.links.type = anyType; + if (t.symbol) { + literalProp.declarations = t.symbol.declarations; + literalProp.valueDeclaration = t.symbol.valueDeclaration; + } + members.set(name, literalProp); + }); + const indexInfos = type.flags & TypeFlags.String ? [createIndexInfo(stringType, emptyObjectType, /*isReadonly*/ false)] : emptyArray; + return createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, indexInfos); + } + + /** + * Infer a suitable input type for a homomorphic mapped type { [P in keyof T]: X }. We construct + * an object type with the same set of properties as the source type, where the type of each + * property is computed by inferring from the source property type to X for the type + * variable T[P] (i.e. we treat the type T[P] as the type variable we're inferring for). + */ + function inferTypeForHomomorphicMappedType(source: Type, target: MappedType, constraint: IndexType): Type | undefined { + const cacheKey = source.id + "," + target.id + "," + constraint.id; + if (reverseMappedCache.has(cacheKey)) { + return reverseMappedCache.get(cacheKey); + } + const type = createReverseMappedType(source, target, constraint); + reverseMappedCache.set(cacheKey, type); + return type; + } + + // We consider a type to be partially inferable if it isn't marked non-inferable or if it is + // an object literal type with at least one property of an inferable type. For example, an object + // literal { a: 123, b: x => true } is marked non-inferable because it contains a context sensitive + // arrow function, but is considered partially inferable because property 'a' has an inferable type. + function isPartiallyInferableType(type: Type): boolean { + return !(getObjectFlags(type) & ObjectFlags.NonInferrableType) || + isObjectLiteralType(type) && some(getPropertiesOfType(type), prop => isPartiallyInferableType(getTypeOfSymbol(prop))) || + isTupleType(type) && some(getElementTypes(type), isPartiallyInferableType); + } + + function createReverseMappedType(source: Type, target: MappedType, constraint: IndexType) { + // We consider a source type reverse mappable if it has a string index signature or if + // it has one or more properties and is of a partially inferable type. + if (!(getIndexInfoOfType(source, stringType) || getPropertiesOfType(source).length !== 0 && isPartiallyInferableType(source))) { + return undefined; + } + // For arrays and tuples we infer new arrays and tuples where the reverse mapping has been + // applied to the element type(s). + if (isArrayType(source)) { + const elementType = inferReverseMappedType(getTypeArguments(source)[0], target, constraint); + if (!elementType) { + return undefined; + } + return createArrayType(elementType, isReadonlyArrayType(source)); + } + if (isTupleType(source)) { + const elementTypes = map(getElementTypes(source), t => inferReverseMappedType(t, target, constraint)); + if (!every(elementTypes, (t): t is Type => !!t)) { + return undefined; + } + const elementFlags = getMappedTypeModifiers(target) & MappedTypeModifiers.IncludeOptional ? + sameMap(source.target.elementFlags, f => f & ElementFlags.Optional ? ElementFlags.Required : f) : + source.target.elementFlags; + return createTupleType(elementTypes, elementFlags, source.target.readonly, source.target.labeledElementDeclarations); + } + // For all other object types we infer a new object type where the reverse mapping has been + // applied to the type of each property. + const reversed = createObjectType(ObjectFlags.ReverseMapped | ObjectFlags.Anonymous, /*symbol*/ undefined) as ReverseMappedType; + reversed.source = source; + reversed.mappedType = target; + reversed.constraintType = constraint; + return reversed; + } + + function getTypeOfReverseMappedSymbol(symbol: ReverseMappedSymbol): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + links.type = inferReverseMappedType(symbol.links.propertyType, symbol.links.mappedType, symbol.links.constraintType) || unknownType; + } + return links.type; + } + + function inferReverseMappedTypeWorker(sourceType: Type, target: MappedType, constraint: IndexType): Type { + const typeParameter = getIndexedAccessType(constraint.type, getTypeParameterFromMappedType(target)) as TypeParameter; + const templateType = getTemplateTypeFromMappedType(target); + const inference = createInferenceInfo(typeParameter); + inferTypes([inference], sourceType, templateType); + return getTypeFromInference(inference) || unknownType; + } + + function inferReverseMappedType(source: Type, target: MappedType, constraint: IndexType): Type | undefined { + const cacheKey = source.id + "," + target.id + "," + constraint.id; + if (reverseMappedCache.has(cacheKey)) { + return reverseMappedCache.get(cacheKey) || unknownType; + } + reverseMappedSourceStack.push(source); + reverseMappedTargetStack.push(target); + const saveExpandingFlags = reverseExpandingFlags; + if (isDeeplyNestedType(source, reverseMappedSourceStack, reverseMappedSourceStack.length, 2)) reverseExpandingFlags |= ExpandingFlags.Source; + if (isDeeplyNestedType(target, reverseMappedTargetStack, reverseMappedTargetStack.length, 2)) reverseExpandingFlags |= ExpandingFlags.Target; + let type; + if (reverseExpandingFlags !== ExpandingFlags.Both) { + type = inferReverseMappedTypeWorker(source, target, constraint); + } + reverseMappedSourceStack.pop(); + reverseMappedTargetStack.pop(); + reverseExpandingFlags = saveExpandingFlags; + reverseMappedCache.set(cacheKey, type); + return type; + } + + function* getUnmatchedProperties(source: Type, target: Type, requireOptionalProperties: boolean, matchDiscriminantProperties: boolean): IterableIterator { + const properties = getPropertiesOfType(target); + for (const targetProp of properties) { + // TODO: remove this when we support static private identifier fields and find other solutions to get privateNamesAndStaticFields test to pass + if (isStaticPrivateIdentifierProperty(targetProp)) { + continue; + } + if (requireOptionalProperties || !(targetProp.flags & SymbolFlags.Optional || getCheckFlags(targetProp) & CheckFlags.Partial)) { + const sourceProp = getPropertyOfType(source, targetProp.escapedName); + if (!sourceProp) { + yield targetProp; + } + else if (matchDiscriminantProperties) { + const targetType = getTypeOfSymbol(targetProp); + if (targetType.flags & TypeFlags.Unit) { + const sourceType = getTypeOfSymbol(sourceProp); + if (!(sourceType.flags & TypeFlags.Any || getRegularTypeOfLiteralType(sourceType) === getRegularTypeOfLiteralType(targetType))) { + yield targetProp; + } + } + } + } + } + } + + function getUnmatchedProperty(source: Type, target: Type, requireOptionalProperties: boolean, matchDiscriminantProperties: boolean): Symbol | undefined { + return firstOrUndefinedIterator(getUnmatchedProperties(source, target, requireOptionalProperties, matchDiscriminantProperties)); + } + + function tupleTypesDefinitelyUnrelated(source: TupleTypeReference, target: TupleTypeReference) { + return !(target.target.combinedFlags & ElementFlags.Variadic) && target.target.minLength > source.target.minLength || + !(target.target.combinedFlags & ElementFlags.Variable) && (!!(source.target.combinedFlags & ElementFlags.Variable) || target.target.fixedLength < source.target.fixedLength); + } + + function typesDefinitelyUnrelated(source: Type, target: Type) { + // Two tuple types with incompatible arities are definitely unrelated. + // Two object types that each have a property that is unmatched in the other are definitely unrelated. + return isTupleType(source) && isTupleType(target) ? tupleTypesDefinitelyUnrelated(source, target) : + !!getUnmatchedProperty(source, target, /*requireOptionalProperties*/ false, /*matchDiscriminantProperties*/ true) && + !!getUnmatchedProperty(target, source, /*requireOptionalProperties*/ false, /*matchDiscriminantProperties*/ false); + } + + function getTypeFromInference(inference: InferenceInfo) { + return inference.candidates ? getUnionType(inference.candidates, UnionReduction.Subtype) : + inference.contraCandidates ? getIntersectionType(inference.contraCandidates) : + undefined; + } + + function hasSkipDirectInferenceFlag(node: Node) { + return !!getNodeLinks(node).skipDirectInference; + } + + function isFromInferenceBlockedSource(type: Type) { + return !!(type.symbol && some(type.symbol.declarations, hasSkipDirectInferenceFlag)); + } + + function templateLiteralTypesDefinitelyUnrelated(source: TemplateLiteralType, target: TemplateLiteralType) { + // Two template literal types with diffences in their starting or ending text spans are definitely unrelated. + const sourceStart = source.texts[0]; + const targetStart = target.texts[0]; + const sourceEnd = source.texts[source.texts.length - 1]; + const targetEnd = target.texts[target.texts.length - 1]; + const startLen = Math.min(sourceStart.length, targetStart.length); + const endLen = Math.min(sourceEnd.length, targetEnd.length); + return sourceStart.slice(0, startLen) !== targetStart.slice(0, startLen) || + sourceEnd.slice(sourceEnd.length - endLen) !== targetEnd.slice(targetEnd.length - endLen); + } + + /** + * Tests whether the provided string can be parsed as a number. + * @param s The string to test. + * @param roundTripOnly Indicates the resulting number matches the input when converted back to a string. + */ + function isValidNumberString(s: string, roundTripOnly: boolean): boolean { + if (s === "") return false; + const n = +s; + return isFinite(n) && (!roundTripOnly || "" + n === s); + } + + /** + * @param text a valid bigint string excluding a trailing `n`, but including a possible prefix `-`. Use `isValidBigIntString(text, roundTripOnly)` before calling this function. + */ + function parseBigIntLiteralType(text: string) { + return getBigIntLiteralType(parseValidBigInt(text)); + } + + function isMemberOfStringMapping(source: Type, target: Type): boolean { + if (target.flags & TypeFlags.Any) { + return true; + } + if (target.flags & (TypeFlags.String | TypeFlags.TemplateLiteral)) { + return isTypeAssignableTo(source, target); + } + if (target.flags & TypeFlags.StringMapping) { + // We need to see whether applying the same mappings of the target + // onto the source would produce an identical type *and* that + // it's compatible with the inner-most non-string-mapped type. + // + // The intuition here is that if same mappings don't affect the source at all, + // and the source is compatible with the unmapped target, then they must + // still reside in the same domain. + const mappingStack = []; + while (target.flags & TypeFlags.StringMapping) { + mappingStack.unshift(target.symbol); + target = (target as StringMappingType).type; + } + const mappedSource = reduceLeft(mappingStack, (memo, value) => getStringMappingType(value, memo), source); + return mappedSource === source && isMemberOfStringMapping(source, target); + } + return false; + } + + function isValidTypeForTemplateLiteralPlaceholder(source: Type, target: Type): boolean { + if (target.flags & TypeFlags.Intersection) { + return every((target as IntersectionType).types, t => t === emptyTypeLiteralType || isValidTypeForTemplateLiteralPlaceholder(source, t)); + } + if (target.flags & TypeFlags.String || isTypeAssignableTo(source, target)) { + return true; + } + if (source.flags & TypeFlags.StringLiteral) { + const value = (source as StringLiteralType).value; + return !!(target.flags & TypeFlags.Number && isValidNumberString(value, /*roundTripOnly*/ false) || + target.flags & TypeFlags.BigInt && isValidBigIntString(value, /*roundTripOnly*/ false) || + target.flags & (TypeFlags.BooleanLiteral | TypeFlags.Nullable) && value === (target as IntrinsicType).intrinsicName || + target.flags & TypeFlags.StringMapping && isMemberOfStringMapping(getStringLiteralType(value), target) || + target.flags & TypeFlags.TemplateLiteral && isTypeMatchedByTemplateLiteralType(source, target as TemplateLiteralType)); + } + if (source.flags & TypeFlags.TemplateLiteral) { + const texts = (source as TemplateLiteralType).texts; + return texts.length === 2 && texts[0] === "" && texts[1] === "" && isTypeAssignableTo((source as TemplateLiteralType).types[0], target); + } + return false; + } + + function inferTypesFromTemplateLiteralType(source: Type, target: TemplateLiteralType): Type[] | undefined { + return source.flags & TypeFlags.StringLiteral ? inferFromLiteralPartsToTemplateLiteral([(source as StringLiteralType).value], emptyArray, target) : + source.flags & TypeFlags.TemplateLiteral ? + arraysEqual((source as TemplateLiteralType).texts, target.texts) ? map((source as TemplateLiteralType).types, (s, i) => { + return isTypeAssignableTo(getBaseConstraintOrType(s), getBaseConstraintOrType(target.types[i])) ? s : getStringLikeTypeForType(s); + }) : + inferFromLiteralPartsToTemplateLiteral((source as TemplateLiteralType).texts, (source as TemplateLiteralType).types, target) : + undefined; + } + + function isTypeMatchedByTemplateLiteralType(source: Type, target: TemplateLiteralType): boolean { + const inferences = inferTypesFromTemplateLiteralType(source, target); + return !!inferences && every(inferences, (r, i) => isValidTypeForTemplateLiteralPlaceholder(r, target.types[i])); + } + + function getStringLikeTypeForType(type: Type) { + return type.flags & (TypeFlags.Any | TypeFlags.StringLike) ? type : getTemplateLiteralType(["", ""], [type]); + } + + // This function infers from the text parts and type parts of a source literal to a target template literal. The number + // of text parts is always one more than the number of type parts, and a source string literal is treated as a source + // with one text part and zero type parts. The function returns an array of inferred string or template literal types + // corresponding to the placeholders in the target template literal, or undefined if the source doesn't match the target. + // + // We first check that the starting source text part matches the starting target text part, and that the ending source + // text part ends matches the ending target text part. We then iterate through the remaining target text parts, finding + // a match for each in the source and inferring string or template literal types created from the segments of the source + // that occur between the matches. During this iteration, seg holds the index of the current text part in the sourceTexts + // array and pos holds the current character position in the current text part. + // + // Consider inference from type `<<${string}>.<${number}-${number}>>` to type `<${string}.${string}>`, i.e. + // sourceTexts = ['<<', '>.<', '-', '>>'] + // sourceTypes = [string, number, number] + // target.texts = ['<', '.', '>'] + // We first match '<' in the target to the start of '<<' in the source and '>' in the target to the end of '>>' in + // the source. The first match for the '.' in target occurs at character 1 in the source text part at index 1, and thus + // the first inference is the template literal type `<${string}>`. The remainder of the source makes up the second + // inference, the template literal type `<${number}-${number}>`. + function inferFromLiteralPartsToTemplateLiteral(sourceTexts: readonly string[], sourceTypes: readonly Type[], target: TemplateLiteralType): Type[] | undefined { + const lastSourceIndex = sourceTexts.length - 1; + const sourceStartText = sourceTexts[0]; + const sourceEndText = sourceTexts[lastSourceIndex]; + const targetTexts = target.texts; + const lastTargetIndex = targetTexts.length - 1; + const targetStartText = targetTexts[0]; + const targetEndText = targetTexts[lastTargetIndex]; + if ( + lastSourceIndex === 0 && sourceStartText.length < targetStartText.length + targetEndText.length || + !sourceStartText.startsWith(targetStartText) || !sourceEndText.endsWith(targetEndText) + ) return undefined; + const remainingEndText = sourceEndText.slice(0, sourceEndText.length - targetEndText.length); + const matches: Type[] = []; + let seg = 0; + let pos = targetStartText.length; + for (let i = 1; i < lastTargetIndex; i++) { + const delim = targetTexts[i]; + if (delim.length > 0) { + let s = seg; + let p = pos; + while (true) { + p = getSourceText(s).indexOf(delim, p); + if (p >= 0) break; + s++; + if (s === sourceTexts.length) return undefined; + p = 0; + } + addMatch(s, p); + pos += delim.length; + } + else if (pos < getSourceText(seg).length) { + addMatch(seg, pos + 1); + } + else if (seg < lastSourceIndex) { + addMatch(seg + 1, 0); + } + else { + return undefined; + } + } + addMatch(lastSourceIndex, getSourceText(lastSourceIndex).length); + return matches; + function getSourceText(index: number) { + return index < lastSourceIndex ? sourceTexts[index] : remainingEndText; + } + function addMatch(s: number, p: number) { + const matchType = s === seg ? + getStringLiteralType(getSourceText(s).slice(pos, p)) : + getTemplateLiteralType( + [sourceTexts[seg].slice(pos), ...sourceTexts.slice(seg + 1, s), getSourceText(s).slice(0, p)], + sourceTypes.slice(seg, s), + ); + matches.push(matchType); + seg = s; + pos = p; + } + } + + /** + * @returns `true` if `type` has the shape `[T[0]]` where `T` is `typeParameter` + */ + function isTupleOfSelf(typeParameter: TypeParameter, type: Type) { + return isTupleType(type) && getTupleElementType(type, 0) === getIndexedAccessType(typeParameter, getNumberLiteralType(0)) && !getTypeOfPropertyOfType(type, "1" as __String); + } + + function inferTypes(inferences: InferenceInfo[], originalSource: Type, originalTarget: Type, priority = InferencePriority.None, contravariant = false) { + let bivariant = false; + let propagationType: Type; + let inferencePriority: number = InferencePriority.MaxValue; + let visited: Map; + let sourceStack: Type[]; + let targetStack: Type[]; + let expandingFlags = ExpandingFlags.None; + inferFromTypes(originalSource, originalTarget); + + function inferFromTypes(source: Type, target: Type): void { + if (!couldContainTypeVariables(target) || isNoInferType(target)) { + return; + } + if (source === wildcardType || source === blockedStringType) { + // We are inferring from an 'any' type. We want to infer this type for every type parameter + // referenced in the target type, so we record it as the propagation type and infer from the + // target to itself. Then, as we find candidates we substitute the propagation type. + const savePropagationType = propagationType; + propagationType = source; + inferFromTypes(target, target); + propagationType = savePropagationType; + return; + } + if (source.aliasSymbol && source.aliasSymbol === target.aliasSymbol) { + if (source.aliasTypeArguments) { + // Source and target are types originating in the same generic type alias declaration. + // Simply infer from source type arguments to target type arguments, with defaults applied. + const params = getSymbolLinks(source.aliasSymbol).typeParameters!; + const minParams = getMinTypeArgumentCount(params); + const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + inferFromTypeArguments(sourceTypes, targetTypes!, getAliasVariances(source.aliasSymbol)); + } + // And if there weren't any type arguments, there's no reason to run inference as the types must be the same. + return; + } + if (source === target && source.flags & TypeFlags.UnionOrIntersection) { + // When source and target are the same union or intersection type, just relate each constituent + // type to itself. + for (const t of (source as UnionOrIntersectionType).types) { + inferFromTypes(t, t); + } + return; + } + if (target.flags & TypeFlags.Union) { + // First, infer between identically matching source and target constituents and remove the + // matching types. + const [tempSources, tempTargets] = inferFromMatchingTypes(source.flags & TypeFlags.Union ? (source as UnionType).types : [source], (target as UnionType).types, isTypeOrBaseIdenticalTo); + // Next, infer between closely matching source and target constituents and remove + // the matching types. Types closely match when they are instantiations of the same + // object type or instantiations of the same type alias. + const [sources, targets] = inferFromMatchingTypes(tempSources, tempTargets, isTypeCloselyMatchedBy); + if (targets.length === 0) { + return; + } + target = getUnionType(targets); + if (sources.length === 0) { + // All source constituents have been matched and there is nothing further to infer from. + // However, simply making no inferences is undesirable because it could ultimately mean + // inferring a type parameter constraint. Instead, make a lower priority inference from + // the full source to whatever remains in the target. For example, when inferring from + // string to 'string | T', make a lower priority inference of string for T. + inferWithPriority(source, target, InferencePriority.NakedTypeVariable); + return; + } + source = getUnionType(sources); + } + else if (target.flags & TypeFlags.Intersection && !every((target as IntersectionType).types, isNonGenericObjectType)) { + // We reduce intersection types unless they're simple combinations of object types. For example, + // when inferring from 'string[] & { extra: any }' to 'string[] & T' we want to remove string[] and + // infer { extra: any } for T. But when inferring to 'string[] & Iterable' we want to keep the + // string[] on the source side and infer string for T. + if (!(source.flags & TypeFlags.Union)) { + // Infer between identically matching source and target constituents and remove the matching types. + const [sources, targets] = inferFromMatchingTypes(source.flags & TypeFlags.Intersection ? (source as IntersectionType).types : [source], (target as IntersectionType).types, isTypeIdenticalTo); + if (sources.length === 0 || targets.length === 0) { + return; + } + source = getIntersectionType(sources); + target = getIntersectionType(targets); + } + } + if (target.flags & (TypeFlags.IndexedAccess | TypeFlags.Substitution)) { + if (isNoInferType(target)) { + return; + } + target = getActualTypeVariable(target); + } + if (target.flags & TypeFlags.TypeVariable) { + // Skip inference if the source is "blocked", which is used by the language service to + // prevent inference on nodes currently being edited. + if (isFromInferenceBlockedSource(source)) { + return; + } + const inference = getInferenceInfoForType(target); + if (inference) { + // If target is a type parameter, make an inference, unless the source type contains + // a "non-inferrable" type. Types with this flag set are markers used to prevent inference. + // + // For example: + // - anyFunctionType is a wildcard type that's used to avoid contextually typing functions; + // it's internal, so should not be exposed to the user by adding it as a candidate. + // - autoType (and autoArrayType) is a special "any" used in control flow; like anyFunctionType, + // it's internal and should not be observable. + // - silentNeverType is returned by getInferredType when instantiating a generic function for + // inference (and a type variable has no mapping). + // + // This flag is infectious; if we produce Box (where never is silentNeverType), Box is + // also non-inferrable. + // + // As a special case, also ignore nonInferrableAnyType, which is a special form of the any type + // used as a stand-in for binding elements when they are being inferred. + if (getObjectFlags(source) & ObjectFlags.NonInferrableType || source === nonInferrableAnyType) { + return; + } + if (!inference.isFixed) { + const candidate = propagationType || source; + if (candidate === blockedStringType) { + return; + } + if (inference.priority === undefined || priority < inference.priority) { + inference.candidates = undefined; + inference.contraCandidates = undefined; + inference.topLevel = true; + inference.priority = priority; + } + if (priority === inference.priority) { + // Inferring A to [A[0]] is a zero information inference (it guarantees A becomes its constraint), but oft arises from generic argument list inferences + // By discarding it early, we can allow more fruitful results to be used instead. + if (isTupleOfSelf(inference.typeParameter, candidate)) { + return; + } + // We make contravariant inferences only if we are in a pure contravariant position, + // i.e. only if we have not descended into a bivariant position. + if (contravariant && !bivariant) { + if (!contains(inference.contraCandidates, candidate)) { + inference.contraCandidates = append(inference.contraCandidates, candidate); + clearCachedInferences(inferences); + } + } + else if (!contains(inference.candidates, candidate)) { + inference.candidates = append(inference.candidates, candidate); + clearCachedInferences(inferences); + } + } + if (!(priority & InferencePriority.ReturnType) && target.flags & TypeFlags.TypeParameter && inference.topLevel && !isTypeParameterAtTopLevel(originalTarget, target as TypeParameter)) { + inference.topLevel = false; + clearCachedInferences(inferences); + } + } + inferencePriority = Math.min(inferencePriority, priority); + return; + } + // Infer to the simplified version of an indexed access, if possible, to (hopefully) expose more bare type parameters to the inference engine + const simplified = getSimplifiedType(target, /*writing*/ false); + if (simplified !== target) { + inferFromTypes(source, simplified); + } + else if (target.flags & TypeFlags.IndexedAccess) { + const indexType = getSimplifiedType((target as IndexedAccessType).indexType, /*writing*/ false); + // Generally simplifications of instantiable indexes are avoided to keep relationship checking correct, however if our target is an access, we can consider + // that key of that access to be "instantiated", since we're looking to find the infernce goal in any way we can. + if (indexType.flags & TypeFlags.Instantiable) { + const simplified = distributeIndexOverObjectType(getSimplifiedType((target as IndexedAccessType).objectType, /*writing*/ false), indexType, /*writing*/ false); + if (simplified && simplified !== target) { + inferFromTypes(source, simplified); + } + } + } + } + if ( + getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && ( + (source as TypeReference).target === (target as TypeReference).target || isArrayType(source) && isArrayType(target) + ) && + !((source as TypeReference).node && (target as TypeReference).node) + ) { + // If source and target are references to the same generic type, infer from type arguments + inferFromTypeArguments(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), getVariances((source as TypeReference).target)); + } + else if (source.flags & TypeFlags.Index && target.flags & TypeFlags.Index) { + inferFromContravariantTypes((source as IndexType).type, (target as IndexType).type); + } + else if ((isLiteralType(source) || source.flags & TypeFlags.String) && target.flags & TypeFlags.Index) { + const empty = createEmptyObjectTypeFromStringLiteral(source); + inferFromContravariantTypesWithPriority(empty, (target as IndexType).type, InferencePriority.LiteralKeyof); + } + else if (source.flags & TypeFlags.IndexedAccess && target.flags & TypeFlags.IndexedAccess) { + inferFromTypes((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType); + inferFromTypes((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType); + } + else if (source.flags & TypeFlags.StringMapping && target.flags & TypeFlags.StringMapping) { + if ((source as StringMappingType).symbol === (target as StringMappingType).symbol) { + inferFromTypes((source as StringMappingType).type, (target as StringMappingType).type); + } + } + else if (source.flags & TypeFlags.Substitution) { + inferFromTypes((source as SubstitutionType).baseType, target); + inferWithPriority(getSubstitutionIntersection(source as SubstitutionType), target, InferencePriority.SubstituteSource); // Make substitute inference at a lower priority + } + else if (target.flags & TypeFlags.Conditional) { + invokeOnce(source, target as ConditionalType, inferToConditionalType); + } + else if (target.flags & TypeFlags.UnionOrIntersection) { + inferToMultipleTypes(source, (target as UnionOrIntersectionType).types, target.flags); + } + else if (source.flags & TypeFlags.Union) { + // Source is a union or intersection type, infer from each constituent type + const sourceTypes = (source as UnionOrIntersectionType).types; + for (const sourceType of sourceTypes) { + inferFromTypes(sourceType, target); + } + } + else if (target.flags & TypeFlags.TemplateLiteral) { + inferToTemplateLiteralType(source, target as TemplateLiteralType); + } + else { + source = getReducedType(source); + if (isGenericMappedType(source) && isGenericMappedType(target)) { + invokeOnce(source, target, inferFromGenericMappedTypes); + } + if (!(priority & InferencePriority.NoConstraints && source.flags & (TypeFlags.Intersection | TypeFlags.Instantiable))) { + const apparentSource = getApparentType(source); + // getApparentType can return _any_ type, since an indexed access or conditional may simplify to any other type. + // If that occurs and it doesn't simplify to an object or intersection, we'll need to restart `inferFromTypes` + // with the simplified source. + if (apparentSource !== source && !(apparentSource.flags & (TypeFlags.Object | TypeFlags.Intersection))) { + return inferFromTypes(apparentSource, target); + } + source = apparentSource; + } + if (source.flags & (TypeFlags.Object | TypeFlags.Intersection)) { + invokeOnce(source, target, inferFromObjectTypes); + } + } + } + + function inferWithPriority(source: Type, target: Type, newPriority: InferencePriority) { + const savePriority = priority; + priority |= newPriority; + inferFromTypes(source, target); + priority = savePriority; + } + + function inferFromContravariantTypesWithPriority(source: Type, target: Type, newPriority: InferencePriority) { + const savePriority = priority; + priority |= newPriority; + inferFromContravariantTypes(source, target); + priority = savePriority; + } + + function inferToMultipleTypesWithPriority(source: Type, targets: Type[], targetFlags: TypeFlags, newPriority: InferencePriority) { + const savePriority = priority; + priority |= newPriority; + inferToMultipleTypes(source, targets, targetFlags); + priority = savePriority; + } + + // Ensure an inference action is performed only once for the given source and target types. + // This includes two things: + // Avoiding inferring between the same pair of source and target types, + // and avoiding circularly inferring between source and target types. + // For an example of the last, consider if we are inferring between source type + // `type Deep = { next: Deep> }` and target type `type Loop = { next: Loop }`. + // We would then infer between the types of the `next` property: `Deep>` = `{ next: Deep>> }` and `Loop` = `{ next: Loop }`. + // We will then infer again between the types of the `next` property: + // `Deep>>` and `Loop`, and so on, such that we would be forever inferring + // between instantiations of the same types `Deep` and `Loop`. + // In particular, we would be inferring from increasingly deep instantiations of `Deep` to `Loop`, + // such that we would go on inferring forever, even though we would never infer + // between the same pair of types. + function invokeOnce(source: Source, target: Target, action: (source: Source, target: Target) => void) { + const key = source.id + "," + target.id; + const status = visited && visited.get(key); + if (status !== undefined) { + inferencePriority = Math.min(inferencePriority, status); + return; + } + (visited || (visited = new Map())).set(key, InferencePriority.Circularity); + const saveInferencePriority = inferencePriority; + inferencePriority = InferencePriority.MaxValue; + // We stop inferring and report a circularity if we encounter duplicate recursion identities on both + // the source side and the target side. + const saveExpandingFlags = expandingFlags; + (sourceStack ??= []).push(source); + (targetStack ??= []).push(target); + if (isDeeplyNestedType(source, sourceStack, sourceStack.length, 2)) expandingFlags |= ExpandingFlags.Source; + if (isDeeplyNestedType(target, targetStack, targetStack.length, 2)) expandingFlags |= ExpandingFlags.Target; + if (expandingFlags !== ExpandingFlags.Both) { + action(source, target); + } + else { + inferencePriority = InferencePriority.Circularity; + } + targetStack.pop(); + sourceStack.pop(); + expandingFlags = saveExpandingFlags; + visited.set(key, inferencePriority); + inferencePriority = Math.min(inferencePriority, saveInferencePriority); + } + + function inferFromMatchingTypes(sources: Type[], targets: Type[], matches: (s: Type, t: Type) => boolean): [Type[], Type[]] { + let matchedSources: Type[] | undefined; + let matchedTargets: Type[] | undefined; + for (const t of targets) { + for (const s of sources) { + if (matches(s, t)) { + inferFromTypes(s, t); + matchedSources = appendIfUnique(matchedSources, s); + matchedTargets = appendIfUnique(matchedTargets, t); + } + } + } + return [ + matchedSources ? filter(sources, t => !contains(matchedSources, t)) : sources, + matchedTargets ? filter(targets, t => !contains(matchedTargets, t)) : targets, + ]; + } + + function inferFromTypeArguments(sourceTypes: readonly Type[], targetTypes: readonly Type[], variances: readonly VarianceFlags[]) { + const count = sourceTypes.length < targetTypes.length ? sourceTypes.length : targetTypes.length; + for (let i = 0; i < count; i++) { + if (i < variances.length && (variances[i] & VarianceFlags.VarianceMask) === VarianceFlags.Contravariant) { + inferFromContravariantTypes(sourceTypes[i], targetTypes[i]); + } + else { + inferFromTypes(sourceTypes[i], targetTypes[i]); + } + } + } + + function inferFromContravariantTypes(source: Type, target: Type) { + contravariant = !contravariant; + inferFromTypes(source, target); + contravariant = !contravariant; + } + + function inferFromContravariantTypesIfStrictFunctionTypes(source: Type, target: Type) { + if (strictFunctionTypes || priority & InferencePriority.AlwaysStrict) { + inferFromContravariantTypes(source, target); + } + else { + inferFromTypes(source, target); + } + } + + function getInferenceInfoForType(type: Type) { + if (type.flags & TypeFlags.TypeVariable) { + for (const inference of inferences) { + if (type === inference.typeParameter) { + return inference; + } + } + } + return undefined; + } + + function getSingleTypeVariableFromIntersectionTypes(types: Type[]) { + let typeVariable: Type | undefined; + for (const type of types) { + const t = type.flags & TypeFlags.Intersection && find((type as IntersectionType).types, t => !!getInferenceInfoForType(t)); + if (!t || typeVariable && t !== typeVariable) { + return undefined; + } + typeVariable = t; + } + return typeVariable; + } + + function inferToMultipleTypes(source: Type, targets: Type[], targetFlags: TypeFlags) { + let typeVariableCount = 0; + if (targetFlags & TypeFlags.Union) { + let nakedTypeVariable: Type | undefined; + const sources = source.flags & TypeFlags.Union ? (source as UnionType).types : [source]; + const matched = new Array(sources.length); + let inferenceCircularity = false; + // First infer to types that are not naked type variables. For each source type we + // track whether inferences were made from that particular type to some target with + // equal priority (i.e. of equal quality) to what we would infer for a naked type + // parameter. + for (const t of targets) { + if (getInferenceInfoForType(t)) { + nakedTypeVariable = t; + typeVariableCount++; + } + else { + for (let i = 0; i < sources.length; i++) { + const saveInferencePriority = inferencePriority; + inferencePriority = InferencePriority.MaxValue; + inferFromTypes(sources[i], t); + if (inferencePriority === priority) matched[i] = true; + inferenceCircularity = inferenceCircularity || inferencePriority === InferencePriority.Circularity; + inferencePriority = Math.min(inferencePriority, saveInferencePriority); + } + } + } + if (typeVariableCount === 0) { + // If every target is an intersection of types containing a single naked type variable, + // make a lower priority inference to that type variable. This handles inferring from + // 'A | B' to 'T & (X | Y)' where we want to infer 'A | B' for T. + const intersectionTypeVariable = getSingleTypeVariableFromIntersectionTypes(targets); + if (intersectionTypeVariable) { + inferWithPriority(source, intersectionTypeVariable, InferencePriority.NakedTypeVariable); + } + return; + } + // If the target has a single naked type variable and no inference circularities were + // encountered above (meaning we explored the types fully), create a union of the source + // types from which no inferences have been made so far and infer from that union to the + // naked type variable. + if (typeVariableCount === 1 && !inferenceCircularity) { + const unmatched = flatMap(sources, (s, i) => matched[i] ? undefined : s); + if (unmatched.length) { + inferFromTypes(getUnionType(unmatched), nakedTypeVariable!); + return; + } + } + } + else { + // We infer from types that are not naked type variables first so that inferences we + // make from nested naked type variables and given slightly higher priority by virtue + // of being first in the candidates array. + for (const t of targets) { + if (getInferenceInfoForType(t)) { + typeVariableCount++; + } + else { + inferFromTypes(source, t); + } + } + } + // Inferences directly to naked type variables are given lower priority as they are + // less specific. For example, when inferring from Promise to T | Promise, + // we want to infer string for T, not Promise | string. For intersection types + // we only infer to single naked type variables. + if (targetFlags & TypeFlags.Intersection ? typeVariableCount === 1 : typeVariableCount > 0) { + for (const t of targets) { + if (getInferenceInfoForType(t)) { + inferWithPriority(source, t, InferencePriority.NakedTypeVariable); + } + } + } + } + + function inferToMappedType(source: Type, target: MappedType, constraintType: Type): boolean { + if ((constraintType.flags & TypeFlags.Union) || (constraintType.flags & TypeFlags.Intersection)) { + let result = false; + for (const type of (constraintType as (UnionType | IntersectionType)).types) { + result = inferToMappedType(source, target, type) || result; + } + return result; + } + if (constraintType.flags & TypeFlags.Index) { + // We're inferring from some source type S to a homomorphic mapped type { [P in keyof T]: X }, + // where T is a type variable. Use inferTypeForHomomorphicMappedType to infer a suitable source + // type and then make a secondary inference from that type to T. We make a secondary inference + // such that direct inferences to T get priority over inferences to Partial, for example. + const inference = getInferenceInfoForType((constraintType as IndexType).type); + if (inference && !inference.isFixed && !isFromInferenceBlockedSource(source)) { + const inferredType = inferTypeForHomomorphicMappedType(source, target, constraintType as IndexType); + if (inferredType) { + // We assign a lower priority to inferences made from types containing non-inferrable + // types because we may only have a partial result (i.e. we may have failed to make + // reverse inferences for some properties). + inferWithPriority( + inferredType, + inference.typeParameter, + getObjectFlags(source) & ObjectFlags.NonInferrableType ? + InferencePriority.PartialHomomorphicMappedType : + InferencePriority.HomomorphicMappedType, + ); + } + } + return true; + } + if (constraintType.flags & TypeFlags.TypeParameter) { + // We're inferring from some source type S to a mapped type { [P in K]: X }, where K is a type + // parameter. First infer from 'keyof S' to K. + inferWithPriority(getIndexType(source, /*indexFlags*/ !!source.pattern ? IndexFlags.NoIndexSignatures : IndexFlags.None), constraintType, InferencePriority.MappedTypeConstraint); + // If K is constrained to a type C, also infer to C. Thus, for a mapped type { [P in K]: X }, + // where K extends keyof T, we make the same inferences as for a homomorphic mapped type + // { [P in keyof T]: X }. This enables us to make meaningful inferences when the target is a + // Pick. + const extendedConstraint = getConstraintOfType(constraintType); + if (extendedConstraint && inferToMappedType(source, target, extendedConstraint)) { + return true; + } + // If no inferences can be made to K's constraint, infer from a union of the property types + // in the source to the template type X. + const propTypes = map(getPropertiesOfType(source), getTypeOfSymbol); + const indexTypes = map(getIndexInfosOfType(source), info => info !== enumNumberIndexInfo ? info.type : neverType); + inferFromTypes(getUnionType(concatenate(propTypes, indexTypes)), getTemplateTypeFromMappedType(target)); + return true; + } + return false; + } + + function inferToConditionalType(source: Type, target: ConditionalType) { + if (source.flags & TypeFlags.Conditional) { + inferFromTypes((source as ConditionalType).checkType, target.checkType); + inferFromTypes((source as ConditionalType).extendsType, target.extendsType); + inferFromTypes(getTrueTypeFromConditionalType(source as ConditionalType), getTrueTypeFromConditionalType(target)); + inferFromTypes(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target)); + } + else { + const targetTypes = [getTrueTypeFromConditionalType(target), getFalseTypeFromConditionalType(target)]; + inferToMultipleTypesWithPriority(source, targetTypes, target.flags, contravariant ? InferencePriority.ContravariantConditional : 0); + } + } + + function inferToTemplateLiteralType(source: Type, target: TemplateLiteralType) { + const matches = inferTypesFromTemplateLiteralType(source, target); + const types = target.types; + // When the target template literal contains only placeholders (meaning that inference is intended to extract + // single characters and remainder strings) and inference fails to produce matches, we want to infer 'never' for + // each placeholder such that instantiation with the inferred value(s) produces 'never', a type for which an + // assignment check will fail. If we make no inferences, we'll likely end up with the constraint 'string' which, + // upon instantiation, would collapse all the placeholders to just 'string', and an assignment check might + // succeed. That would be a pointless and confusing outcome. + if (matches || every(target.texts, s => s.length === 0)) { + for (let i = 0; i < types.length; i++) { + const source = matches ? matches[i] : neverType; + const target = types[i]; + + // If we are inferring from a string literal type to a type variable whose constraint includes one of the + // allowed template literal placeholder types, infer from a literal type corresponding to the constraint. + if (source.flags & TypeFlags.StringLiteral && target.flags & TypeFlags.TypeVariable) { + const inferenceContext = getInferenceInfoForType(target); + const constraint = inferenceContext ? getBaseConstraintOfType(inferenceContext.typeParameter) : undefined; + if (constraint && !isTypeAny(constraint)) { + const constraintTypes = constraint.flags & TypeFlags.Union ? (constraint as UnionType).types : [constraint]; + let allTypeFlags: TypeFlags = reduceLeft(constraintTypes, (flags, t) => flags | t.flags, 0 as TypeFlags); + + // If the constraint contains `string`, we don't need to look for a more preferred type + if (!(allTypeFlags & TypeFlags.String)) { + const str = (source as StringLiteralType).value; + + // If the type contains `number` or a number literal and the string isn't a valid number, exclude numbers + if (allTypeFlags & TypeFlags.NumberLike && !isValidNumberString(str, /*roundTripOnly*/ true)) { + allTypeFlags &= ~TypeFlags.NumberLike; + } + + // If the type contains `bigint` or a bigint literal and the string isn't a valid bigint, exclude bigints + if (allTypeFlags & TypeFlags.BigIntLike && !isValidBigIntString(str, /*roundTripOnly*/ true)) { + allTypeFlags &= ~TypeFlags.BigIntLike; + } + + // for each type in the constraint, find the highest priority matching type + const matchingType = reduceLeft(constraintTypes, (left, right) => + !(right.flags & allTypeFlags) ? left : + left.flags & TypeFlags.String ? left : right.flags & TypeFlags.String ? source : + left.flags & TypeFlags.TemplateLiteral ? left : right.flags & TypeFlags.TemplateLiteral && isTypeMatchedByTemplateLiteralType(source, right as TemplateLiteralType) ? source : + left.flags & TypeFlags.StringMapping ? left : right.flags & TypeFlags.StringMapping && str === applyStringMapping(right.symbol, str) ? source : + left.flags & TypeFlags.StringLiteral ? left : right.flags & TypeFlags.StringLiteral && (right as StringLiteralType).value === str ? right : + left.flags & TypeFlags.Number ? left : right.flags & TypeFlags.Number ? getNumberLiteralType(+str) : + left.flags & TypeFlags.Enum ? left : right.flags & TypeFlags.Enum ? getNumberLiteralType(+str) : + left.flags & TypeFlags.NumberLiteral ? left : right.flags & TypeFlags.NumberLiteral && (right as NumberLiteralType).value === +str ? right : + left.flags & TypeFlags.BigInt ? left : right.flags & TypeFlags.BigInt ? parseBigIntLiteralType(str) : + left.flags & TypeFlags.BigIntLiteral ? left : right.flags & TypeFlags.BigIntLiteral && pseudoBigIntToString((right as BigIntLiteralType).value) === str ? right : + left.flags & TypeFlags.Boolean ? left : right.flags & TypeFlags.Boolean ? str === "true" ? trueType : str === "false" ? falseType : booleanType : + left.flags & TypeFlags.BooleanLiteral ? left : right.flags & TypeFlags.BooleanLiteral && (right as IntrinsicType).intrinsicName === str ? right : + left.flags & TypeFlags.Undefined ? left : right.flags & TypeFlags.Undefined && (right as IntrinsicType).intrinsicName === str ? right : + left.flags & TypeFlags.Null ? left : right.flags & TypeFlags.Null && (right as IntrinsicType).intrinsicName === str ? right : + left, neverType as Type); + + if (!(matchingType.flags & TypeFlags.Never)) { + inferFromTypes(matchingType, target); + continue; + } + } + } + } + + inferFromTypes(source, target); + } + } + } + + function inferFromGenericMappedTypes(source: MappedType, target: MappedType) { + // The source and target types are generic types { [P in S]: X } and { [P in T]: Y }, so we infer + // from S to T and from X to Y. + inferFromTypes(getConstraintTypeFromMappedType(source), getConstraintTypeFromMappedType(target)); + inferFromTypes(getTemplateTypeFromMappedType(source), getTemplateTypeFromMappedType(target)); + const sourceNameType = getNameTypeFromMappedType(source); + const targetNameType = getNameTypeFromMappedType(target); + if (sourceNameType && targetNameType) inferFromTypes(sourceNameType, targetNameType); + } + + function inferFromObjectTypes(source: Type, target: Type) { + if ( + getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && ( + (source as TypeReference).target === (target as TypeReference).target || isArrayType(source) && isArrayType(target) + ) + ) { + // If source and target are references to the same generic type, infer from type arguments + inferFromTypeArguments(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), getVariances((source as TypeReference).target)); + return; + } + if (isGenericMappedType(source) && isGenericMappedType(target)) { + inferFromGenericMappedTypes(source, target); + } + if (getObjectFlags(target) & ObjectFlags.Mapped && !(target as MappedType).declaration.nameType) { + const constraintType = getConstraintTypeFromMappedType(target as MappedType); + if (inferToMappedType(source, target as MappedType, constraintType)) { + return; + } + } + // Infer from the members of source and target only if the two types are possibly related + if (!typesDefinitelyUnrelated(source, target)) { + if (isArrayOrTupleType(source)) { + if (isTupleType(target)) { + const sourceArity = getTypeReferenceArity(source); + const targetArity = getTypeReferenceArity(target); + const elementTypes = getTypeArguments(target); + const elementFlags = target.target.elementFlags; + // When source and target are tuple types with the same structure (fixed, variadic, and rest are matched + // to the same kind in each position), simply infer between the element types. + if (isTupleType(source) && isTupleTypeStructureMatching(source, target)) { + for (let i = 0; i < targetArity; i++) { + inferFromTypes(getTypeArguments(source)[i], elementTypes[i]); + } + return; + } + const startLength = isTupleType(source) ? Math.min(source.target.fixedLength, target.target.fixedLength) : 0; + const endLength = Math.min(isTupleType(source) ? getEndElementCount(source.target, ElementFlags.Fixed) : 0, target.target.combinedFlags & ElementFlags.Variable ? getEndElementCount(target.target, ElementFlags.Fixed) : 0); + // Infer between starting fixed elements. + for (let i = 0; i < startLength; i++) { + inferFromTypes(getTypeArguments(source)[i], elementTypes[i]); + } + if (!isTupleType(source) || sourceArity - startLength - endLength === 1 && source.target.elementFlags[startLength] & ElementFlags.Rest) { + // Single rest element remains in source, infer from that to every element in target + const restType = getTypeArguments(source)[startLength]; + for (let i = startLength; i < targetArity - endLength; i++) { + inferFromTypes(elementFlags[i] & ElementFlags.Variadic ? createArrayType(restType) : restType, elementTypes[i]); + } + } + else { + const middleLength = targetArity - startLength - endLength; + if (middleLength === 2) { + if (elementFlags[startLength] & elementFlags[startLength + 1] & ElementFlags.Variadic) { + // Middle of target is [...T, ...U] and source is tuple type + const targetInfo = getInferenceInfoForType(elementTypes[startLength]); + if (targetInfo && targetInfo.impliedArity !== undefined) { + // Infer slices from source based on implied arity of T. + inferFromTypes(sliceTupleType(source, startLength, endLength + sourceArity - targetInfo.impliedArity), elementTypes[startLength]); + inferFromTypes(sliceTupleType(source, startLength + targetInfo.impliedArity, endLength), elementTypes[startLength + 1]); + } + } + else if (elementFlags[startLength] & ElementFlags.Variadic && elementFlags[startLength + 1] & ElementFlags.Rest) { + // Middle of target is [...T, ...rest] and source is tuple type + // if T is constrained by a fixed-size tuple we might be able to use its arity to infer T + const param = getInferenceInfoForType(elementTypes[startLength])?.typeParameter; + const constraint = param && getBaseConstraintOfType(param); + if (constraint && isTupleType(constraint) && !(constraint.target.combinedFlags & ElementFlags.Variable)) { + const impliedArity = constraint.target.fixedLength; + inferFromTypes(sliceTupleType(source, startLength, sourceArity - (startLength + impliedArity)), elementTypes[startLength]); + inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength + impliedArity, endLength)!, elementTypes[startLength + 1]); + } + } + else if (elementFlags[startLength] & ElementFlags.Rest && elementFlags[startLength + 1] & ElementFlags.Variadic) { + // Middle of target is [...rest, ...T] and source is tuple type + // if T is constrained by a fixed-size tuple we might be able to use its arity to infer T + const param = getInferenceInfoForType(elementTypes[startLength + 1])?.typeParameter; + const constraint = param && getBaseConstraintOfType(param); + if (constraint && isTupleType(constraint) && !(constraint.target.combinedFlags & ElementFlags.Variable)) { + const impliedArity = constraint.target.fixedLength; + const endIndex = sourceArity - getEndElementCount(target.target, ElementFlags.Fixed); + const startIndex = endIndex - impliedArity; + const trailingSlice = createTupleType(getTypeArguments(source).slice(startIndex, endIndex), source.target.elementFlags.slice(startIndex, endIndex), /*readonly*/ false, source.target.labeledElementDeclarations && source.target.labeledElementDeclarations.slice(startIndex, endIndex)); + + inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength, endLength + impliedArity)!, elementTypes[startLength]); + inferFromTypes(trailingSlice, elementTypes[startLength + 1]); + } + } + } + else if (middleLength === 1 && elementFlags[startLength] & ElementFlags.Variadic) { + // Middle of target is exactly one variadic element. Infer the slice between the fixed parts in the source. + // If target ends in optional element(s), make a lower priority a speculative inference. + const endsInOptional = target.target.elementFlags[targetArity - 1] & ElementFlags.Optional; + const sourceSlice = sliceTupleType(source, startLength, endLength); + inferWithPriority(sourceSlice, elementTypes[startLength], endsInOptional ? InferencePriority.SpeculativeTuple : 0); + } + else if (middleLength === 1 && elementFlags[startLength] & ElementFlags.Rest) { + // Middle of target is exactly one rest element. If middle of source is not empty, infer union of middle element types. + const restType = getElementTypeOfSliceOfTupleType(source, startLength, endLength); + if (restType) { + inferFromTypes(restType, elementTypes[startLength]); + } + } + } + // Infer between ending fixed elements + for (let i = 0; i < endLength; i++) { + inferFromTypes(getTypeArguments(source)[sourceArity - i - 1], elementTypes[targetArity - i - 1]); + } + return; + } + if (isArrayType(target)) { + inferFromIndexTypes(source, target); + return; + } + } + inferFromProperties(source, target); + inferFromSignatures(source, target, SignatureKind.Call); + inferFromSignatures(source, target, SignatureKind.Construct); + inferFromIndexTypes(source, target); + } + } + + function inferFromProperties(source: Type, target: Type) { + const properties = getPropertiesOfObjectType(target); + for (const targetProp of properties) { + const sourceProp = getPropertyOfType(source, targetProp.escapedName); + if (sourceProp && !some(sourceProp.declarations, hasSkipDirectInferenceFlag)) { + inferFromTypes( + removeMissingType(getTypeOfSymbol(sourceProp), !!(sourceProp.flags & SymbolFlags.Optional)), + removeMissingType(getTypeOfSymbol(targetProp), !!(targetProp.flags & SymbolFlags.Optional)), + ); + } + } + } + + function inferFromSignatures(source: Type, target: Type, kind: SignatureKind) { + const sourceSignatures = getSignaturesOfType(source, kind); + const sourceLen = sourceSignatures.length; + if (sourceLen > 0) { + // We match source and target signatures from the bottom up, and if the source has fewer signatures + // than the target, we infer from the first source signature to the excess target signatures. + const targetSignatures = getSignaturesOfType(target, kind); + const targetLen = targetSignatures.length; + for (let i = 0; i < targetLen; i++) { + const sourceIndex = Math.max(sourceLen - targetLen + i, 0); + inferFromSignature(getBaseSignature(sourceSignatures[sourceIndex]), getErasedSignature(targetSignatures[i])); + } + } + } + + function inferFromSignature(source: Signature, target: Signature) { + if (!(source.flags & SignatureFlags.IsNonInferrable)) { + const saveBivariant = bivariant; + const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown; + // Once we descend into a bivariant signature we remain bivariant for all nested inferences + bivariant = bivariant || kind === SyntaxKind.MethodDeclaration || kind === SyntaxKind.MethodSignature || kind === SyntaxKind.Constructor; + applyToParameterTypes(source, target, inferFromContravariantTypesIfStrictFunctionTypes); + bivariant = saveBivariant; + } + applyToReturnTypes(source, target, inferFromTypes); + } + + function inferFromIndexTypes(source: Type, target: Type) { + // Inferences across mapped type index signatures are pretty much the same a inferences to homomorphic variables + const priority = (getObjectFlags(source) & getObjectFlags(target) & ObjectFlags.Mapped) ? InferencePriority.HomomorphicMappedType : 0; + const indexInfos = getIndexInfosOfType(target); + if (isObjectTypeWithInferableIndex(source)) { + for (const targetInfo of indexInfos) { + const propTypes: Type[] = []; + for (const prop of getPropertiesOfType(source)) { + if (isApplicableIndexType(getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique), targetInfo.keyType)) { + const propType = getTypeOfSymbol(prop); + propTypes.push(prop.flags & SymbolFlags.Optional ? removeMissingOrUndefinedType(propType) : propType); + } + } + for (const info of getIndexInfosOfType(source)) { + if (isApplicableIndexType(info.keyType, targetInfo.keyType)) { + propTypes.push(info.type); + } + } + if (propTypes.length) { + inferWithPriority(getUnionType(propTypes), targetInfo.type, priority); + } + } + } + for (const targetInfo of indexInfos) { + const sourceInfo = getApplicableIndexInfo(source, targetInfo.keyType); + if (sourceInfo) { + inferWithPriority(sourceInfo.type, targetInfo.type, priority); + } + } + } + } + + function isTypeOrBaseIdenticalTo(s: Type, t: Type) { + return t === missingType ? s === t : + (isTypeIdenticalTo(s, t) || !!(t.flags & TypeFlags.String && s.flags & TypeFlags.StringLiteral || t.flags & TypeFlags.Number && s.flags & TypeFlags.NumberLiteral)); + } + + function isTypeCloselyMatchedBy(s: Type, t: Type) { + return !!(s.flags & TypeFlags.Object && t.flags & TypeFlags.Object && s.symbol && s.symbol === t.symbol || + s.aliasSymbol && s.aliasTypeArguments && s.aliasSymbol === t.aliasSymbol); + } + + function hasPrimitiveConstraint(type: TypeParameter): boolean { + const constraint = getConstraintOfTypeParameter(type); + return !!constraint && maybeTypeOfKind(constraint.flags & TypeFlags.Conditional ? getDefaultConstraintOfConditionalType(constraint as ConditionalType) : constraint, TypeFlags.Primitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping); + } + + function isObjectLiteralType(type: Type) { + return !!(getObjectFlags(type) & ObjectFlags.ObjectLiteral); + } + + function isObjectOrArrayLiteralType(type: Type) { + return !!(getObjectFlags(type) & (ObjectFlags.ObjectLiteral | ObjectFlags.ArrayLiteral)); + } + + function unionObjectAndArrayLiteralCandidates(candidates: Type[]): Type[] { + if (candidates.length > 1) { + const objectLiterals = filter(candidates, isObjectOrArrayLiteralType); + if (objectLiterals.length) { + const literalsType = getUnionType(objectLiterals, UnionReduction.Subtype); + return concatenate(filter(candidates, t => !isObjectOrArrayLiteralType(t)), [literalsType]); + } + } + return candidates; + } + + function getContravariantInference(inference: InferenceInfo) { + return inference.priority! & InferencePriority.PriorityImpliesCombination ? getIntersectionType(inference.contraCandidates!) : getCommonSubtype(inference.contraCandidates!); + } + + function getCovariantInference(inference: InferenceInfo, signature: Signature) { + // Extract all object and array literal types and replace them with a single widened and normalized type. + const candidates = unionObjectAndArrayLiteralCandidates(inference.candidates!); + // We widen inferred literal types if + // all inferences were made to top-level occurrences of the type parameter, and + // the type parameter has no constraint or its constraint includes no primitive or literal types, and + // the type parameter was fixed during inference or does not occur at top-level in the return type. + const primitiveConstraint = hasPrimitiveConstraint(inference.typeParameter) || isConstTypeVariable(inference.typeParameter); + const widenLiteralTypes = !primitiveConstraint && inference.topLevel && + (inference.isFixed || !isTypeParameterAtTopLevelInReturnType(signature, inference.typeParameter)); + const baseCandidates = primitiveConstraint ? sameMap(candidates, getRegularTypeOfLiteralType) : + widenLiteralTypes ? sameMap(candidates, getWidenedLiteralType) : + candidates; + // If all inferences were made from a position that implies a combined result, infer a union type. + // Otherwise, infer a common supertype. + const unwidenedType = inference.priority! & InferencePriority.PriorityImpliesCombination ? + getUnionType(baseCandidates, UnionReduction.Subtype) : + getCommonSupertype(baseCandidates); + return getWidenedType(unwidenedType); + } + + function getInferredType(context: InferenceContext, index: number): Type { + const inference = context.inferences[index]; + if (!inference.inferredType) { + let inferredType: Type | undefined; + let fallbackType: Type | undefined; + if (context.signature) { + const inferredCovariantType = inference.candidates ? getCovariantInference(inference, context.signature) : undefined; + const inferredContravariantType = inference.contraCandidates ? getContravariantInference(inference) : undefined; + if (inferredCovariantType || inferredContravariantType) { + // If we have both co- and contra-variant inferences, we prefer the co-variant inference if it is not 'never', + // all co-variant inferences are assignable to it (i.e. it isn't one of a conflicting set of candidates), it is + // assignable to some contra-variant inference, and no other type parameter is constrained to this type parameter + // and has inferences that would conflict. Otherwise, we prefer the contra-variant inference. + // Similarly ignore co-variant `any` inference when both are available as almost everything is assignable to it + // and it would spoil the overall inference. + const preferCovariantType = inferredCovariantType && (!inferredContravariantType || + !(inferredCovariantType.flags & (TypeFlags.Never | TypeFlags.Any)) && + some(inference.contraCandidates, t => isTypeAssignableTo(inferredCovariantType, t)) && + every(context.inferences, other => + other !== inference && getConstraintOfTypeParameter(other.typeParameter) !== inference.typeParameter || + every(other.candidates, t => isTypeAssignableTo(t, inferredCovariantType)))); + inferredType = preferCovariantType ? inferredCovariantType : inferredContravariantType; + fallbackType = preferCovariantType ? inferredContravariantType : inferredCovariantType; + } + else if (context.flags & InferenceFlags.NoDefault) { + // We use silentNeverType as the wildcard that signals no inferences. + inferredType = silentNeverType; + } + else { + // Infer either the default or the empty object type when no inferences were + // made. It is important to remember that in this case, inference still + // succeeds, meaning there is no error for not having inference candidates. An + // inference error only occurs when there are *conflicting* candidates, i.e. + // candidates with no common supertype. + const defaultType = getDefaultFromTypeParameter(inference.typeParameter); + if (defaultType) { + // Instantiate the default type. Any forward reference to a type + // parameter should be instantiated to the empty object type. + inferredType = instantiateType(defaultType, mergeTypeMappers(createBackreferenceMapper(context, index), context.nonFixingMapper)); + } + } + } + else { + inferredType = getTypeFromInference(inference); + } + + inference.inferredType = inferredType || getDefaultTypeArgumentType(!!(context.flags & InferenceFlags.AnyDefault)); + + const constraint = getConstraintOfTypeParameter(inference.typeParameter); + if (constraint) { + const instantiatedConstraint = instantiateType(constraint, context.nonFixingMapper); + if (!inferredType || !context.compareTypes(inferredType, getTypeWithThisArgument(instantiatedConstraint, inferredType))) { + // If the fallback type satisfies the constraint, we pick it. Otherwise, we pick the constraint. + inference.inferredType = fallbackType && context.compareTypes(fallbackType, getTypeWithThisArgument(instantiatedConstraint, fallbackType)) ? fallbackType : instantiatedConstraint; + } + } + } + + return inference.inferredType; + } + + function getDefaultTypeArgumentType(isInJavaScriptFile: boolean): Type { + return isInJavaScriptFile ? anyType : unknownType; + } + + function getInferredTypes(context: InferenceContext): Type[] { + const result: Type[] = []; + for (let i = 0; i < context.inferences.length; i++) { + result.push(getInferredType(context, i)); + } + return result; + } + + // EXPRESSION TYPE CHECKING + + function getCannotFindNameDiagnosticForName(node: Identifier): DiagnosticMessage { + switch (node.escapedText) { + case "document": + case "console": + return Diagnostics.Cannot_find_name_0_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_include_dom; + case "$": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_jQuery_Try_npm_i_save_dev_types_Slashjquery_and_then_add_jquery_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_jQuery_Try_npm_i_save_dev_types_Slashjquery; + case "describe": + case "suite": + case "it": + case "test": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_a_test_runner_Try_npm_i_save_dev_types_Slashjest_or_npm_i_save_dev_types_Slashmocha_and_then_add_jest_or_mocha_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_a_test_runner_Try_npm_i_save_dev_types_Slashjest_or_npm_i_save_dev_types_Slashmocha; + case "process": + case "require": + case "Buffer": + case "module": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_node_Try_npm_i_save_dev_types_Slashnode_and_then_add_node_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_node_Try_npm_i_save_dev_types_Slashnode; + case "Bun": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_Bun_Try_npm_i_save_dev_types_Slashbun_and_then_add_bun_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_Bun_Try_npm_i_save_dev_types_Slashbun; + case "Map": + case "Set": + case "Promise": + case "Symbol": + case "WeakMap": + case "WeakSet": + case "Iterator": + case "AsyncIterator": + case "SharedArrayBuffer": + case "Atomics": + case "AsyncIterable": + case "AsyncIterableIterator": + case "AsyncGenerator": + case "AsyncGeneratorFunction": + case "BigInt": + case "Reflect": + case "BigInt64Array": + case "BigUint64Array": + return Diagnostics.Cannot_find_name_0_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_1_or_later; + case "await": + if (isCallExpression(node.parent)) { + return Diagnostics.Cannot_find_name_0_Did_you_mean_to_write_this_in_an_async_function; + } + // falls through + default: + if (node.parent.kind === SyntaxKind.ShorthandPropertyAssignment) { + return Diagnostics.No_value_exists_in_scope_for_the_shorthand_property_0_Either_declare_one_or_provide_an_initializer; + } + else { + return Diagnostics.Cannot_find_name_0; + } + } + } + + function getResolvedSymbol(node: Identifier): Symbol { + const links = getNodeLinks(node); + if (!links.resolvedSymbol) { + links.resolvedSymbol = !nodeIsMissing(node) && + resolveName( + node, + node, + SymbolFlags.Value | SymbolFlags.ExportValue, + getCannotFindNameDiagnosticForName(node), + !isWriteOnlyAccess(node), + /*excludeGlobals*/ false, + ) || unknownSymbol; + } + return links.resolvedSymbol; + } + + function isInAmbientOrTypeNode(node: Node): boolean { + return !!(node.flags & NodeFlags.Ambient || findAncestor(node, n => isInterfaceDeclaration(n) || isTypeAliasDeclaration(n) || isTypeLiteralNode(n))); + } + + // Return the flow cache key for a "dotted name" (i.e. a sequence of identifiers + // separated by dots). The key consists of the id of the symbol referenced by the + // leftmost identifier followed by zero or more property names separated by dots. + // The result is undefined if the reference isn't a dotted name. + function getFlowCacheKey(node: Node, declaredType: Type, initialType: Type, flowContainer: Node | undefined): string | undefined { + switch (node.kind) { + case SyntaxKind.Identifier: + if (!isThisInTypeQuery(node)) { + const symbol = getResolvedSymbol(node as Identifier); + return symbol !== unknownSymbol ? `${flowContainer ? getNodeId(flowContainer) : "-1"}|${getTypeId(declaredType)}|${getTypeId(initialType)}|${getSymbolId(symbol)}` : undefined; + } + // falls through + case SyntaxKind.ThisKeyword: + return `0|${flowContainer ? getNodeId(flowContainer) : "-1"}|${getTypeId(declaredType)}|${getTypeId(initialType)}`; + case SyntaxKind.NonNullExpression: + case SyntaxKind.ParenthesizedExpression: + return getFlowCacheKey((node as NonNullExpression | ParenthesizedExpression).expression, declaredType, initialType, flowContainer); + case SyntaxKind.QualifiedName: + const left = getFlowCacheKey((node as QualifiedName).left, declaredType, initialType, flowContainer); + return left && `${left}.${(node as QualifiedName).right.escapedText}`; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + const propName = getAccessedPropertyName(node as AccessExpression); + if (propName !== undefined) { + const key = getFlowCacheKey((node as AccessExpression).expression, declaredType, initialType, flowContainer); + return key && `${key}.${propName}`; + } + if (isElementAccessExpression(node) && isIdentifier(node.argumentExpression)) { + const symbol = getResolvedSymbol(node.argumentExpression); + if (isConstantVariable(symbol) || isParameterOrMutableLocalVariable(symbol) && !isSymbolAssigned(symbol)) { + const key = getFlowCacheKey((node as AccessExpression).expression, declaredType, initialType, flowContainer); + return key && `${key}.@${getSymbolId(symbol)}`; + } + } + break; + case SyntaxKind.ObjectBindingPattern: + case SyntaxKind.ArrayBindingPattern: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + // Handle pseudo-references originating in getNarrowedTypeOfSymbol. + return `${getNodeId(node)}#${getTypeId(declaredType)}`; + } + return undefined; + } + + function isMatchingReference(source: Node, target: Node): boolean { + switch (target.kind) { + case SyntaxKind.ParenthesizedExpression: + case SyntaxKind.NonNullExpression: + return isMatchingReference(source, (target as NonNullExpression | ParenthesizedExpression).expression); + case SyntaxKind.BinaryExpression: + return (isAssignmentExpression(target) && isMatchingReference(source, target.left)) || + (isBinaryExpression(target) && target.operatorToken.kind === SyntaxKind.CommaToken && isMatchingReference(source, target.right)); + } + switch (source.kind) { + case SyntaxKind.MetaProperty: + return target.kind === SyntaxKind.MetaProperty + && (source as MetaProperty).keywordToken === (target as MetaProperty).keywordToken + && (source as MetaProperty).name.escapedText === (target as MetaProperty).name.escapedText; + case SyntaxKind.Identifier: + case SyntaxKind.PrivateIdentifier: + return isThisInTypeQuery(source) ? + target.kind === SyntaxKind.ThisKeyword : + target.kind === SyntaxKind.Identifier && getResolvedSymbol(source as Identifier) === getResolvedSymbol(target as Identifier) || + (isVariableDeclaration(target) || isBindingElement(target)) && + getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(source as Identifier)) === getSymbolOfDeclaration(target); + case SyntaxKind.ThisKeyword: + return target.kind === SyntaxKind.ThisKeyword; + case SyntaxKind.SuperKeyword: + return target.kind === SyntaxKind.SuperKeyword; + case SyntaxKind.NonNullExpression: + case SyntaxKind.ParenthesizedExpression: + return isMatchingReference((source as NonNullExpression | ParenthesizedExpression).expression, target); + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + const sourcePropertyName = getAccessedPropertyName(source as AccessExpression); + if (sourcePropertyName !== undefined) { + const targetPropertyName = isAccessExpression(target) ? getAccessedPropertyName(target) : undefined; + if (targetPropertyName !== undefined) { + return targetPropertyName === sourcePropertyName && isMatchingReference((source as AccessExpression).expression, (target as AccessExpression).expression); + } + } + if (isElementAccessExpression(source) && isElementAccessExpression(target) && isIdentifier(source.argumentExpression) && isIdentifier(target.argumentExpression)) { + const symbol = getResolvedSymbol(source.argumentExpression); + if (symbol === getResolvedSymbol(target.argumentExpression) && (isConstantVariable(symbol) || isParameterOrMutableLocalVariable(symbol) && !isSymbolAssigned(symbol))) { + return isMatchingReference(source.expression, target.expression); + } + } + break; + case SyntaxKind.QualifiedName: + return isAccessExpression(target) && + (source as QualifiedName).right.escapedText === getAccessedPropertyName(target) && + isMatchingReference((source as QualifiedName).left, target.expression); + case SyntaxKind.BinaryExpression: + return (isBinaryExpression(source) && source.operatorToken.kind === SyntaxKind.CommaToken && isMatchingReference(source.right, target)); + } + return false; + } + + function getAccessedPropertyName(access: AccessExpression | BindingElement | ParameterDeclaration): __String | undefined { + if (isPropertyAccessExpression(access)) { + return access.name.escapedText; + } + if (isElementAccessExpression(access)) { + return tryGetElementAccessExpressionName(access); + } + if (isBindingElement(access)) { + const name = getDestructuringPropertyName(access); + return name ? escapeLeadingUnderscores(name) : undefined; + } + if (isParameter(access)) { + return ("" + access.parent.parameters.indexOf(access)) as __String; + } + return undefined; + } + + function tryGetNameFromType(type: Type) { + return type.flags & TypeFlags.UniqueESSymbol ? (type as UniqueESSymbolType).escapedName : + type.flags & TypeFlags.StringOrNumberLiteral ? escapeLeadingUnderscores("" + (type as StringLiteralType | NumberLiteralType).value) : undefined; + } + + function tryGetElementAccessExpressionName(node: ElementAccessExpression) { + return isStringOrNumericLiteralLike(node.argumentExpression) ? escapeLeadingUnderscores(node.argumentExpression.text) : + isEntityNameExpression(node.argumentExpression) ? tryGetNameFromEntityNameExpression(node.argumentExpression) : undefined; + } + + function tryGetNameFromEntityNameExpression(node: EntityNameOrEntityNameExpression) { + const symbol = resolveEntityName(node, SymbolFlags.Value, /*ignoreErrors*/ true); + if (!symbol || !(isConstantVariable(symbol) || (symbol.flags & SymbolFlags.EnumMember))) return undefined; + + const declaration = symbol.valueDeclaration; + if (declaration === undefined) return undefined; + + const type = tryGetTypeFromEffectiveTypeNode(declaration); + if (type) { + const name = tryGetNameFromType(type); + if (name !== undefined) { + return name; + } + } + if (hasOnlyExpressionInitializer(declaration) && isBlockScopedNameDeclaredBeforeUse(declaration, node)) { + const initializer = getEffectiveInitializer(declaration); + if (initializer) { + const initializerType = isBindingPattern(declaration.parent) ? getTypeForBindingElement(declaration as BindingElement) : getTypeOfExpression(initializer); + return initializerType && tryGetNameFromType(initializerType); + } + if (isEnumMember(declaration)) { + return getTextOfPropertyName(declaration.name); + } + } + return undefined; + } + + function containsMatchingReference(source: Node, target: Node) { + while (isAccessExpression(source)) { + source = source.expression; + if (isMatchingReference(source, target)) { + return true; + } + } + return false; + } + + function optionalChainContainsReference(source: Node, target: Node) { + while (isOptionalChain(source)) { + source = source.expression; + if (isMatchingReference(source, target)) { + return true; + } + } + return false; + } + + function isDiscriminantProperty(type: Type | undefined, name: __String) { + if (type && type.flags & TypeFlags.Union) { + const prop = getUnionOrIntersectionProperty(type as UnionType, name); + if (prop && getCheckFlags(prop) & CheckFlags.SyntheticProperty) { + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.SyntheticProperty + if ((prop as TransientSymbol).links.isDiscriminantProperty === undefined) { + (prop as TransientSymbol).links.isDiscriminantProperty = ((prop as TransientSymbol).links.checkFlags & CheckFlags.Discriminant) === CheckFlags.Discriminant && + !isGenericType(getTypeOfSymbol(prop)); + } + return !!(prop as TransientSymbol).links.isDiscriminantProperty; + } + } + return false; + } + + function findDiscriminantProperties(sourceProperties: Symbol[], target: Type): Symbol[] | undefined { + let result: Symbol[] | undefined; + for (const sourceProperty of sourceProperties) { + if (isDiscriminantProperty(target, sourceProperty.escapedName)) { + if (result) { + result.push(sourceProperty); + continue; + } + result = [sourceProperty]; + } + } + return result; + } + + // Given a set of constituent types and a property name, create and return a map keyed by the literal + // types of the property by that name in each constituent type. No map is returned if some key property + // has a non-literal type or if less than 10 or less than 50% of the constituents have a unique key. + // Entries with duplicate keys have unknownType as the value. + function mapTypesByKeyProperty(types: Type[], name: __String) { + const map = new Map(); + let count = 0; + for (const type of types) { + if (type.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive)) { + const discriminant = getTypeOfPropertyOfType(type, name); + if (discriminant) { + if (!isLiteralType(discriminant)) { + return undefined; + } + let duplicate = false; + forEachType(discriminant, t => { + const id = getTypeId(getRegularTypeOfLiteralType(t)); + const existing = map.get(id); + if (!existing) { + map.set(id, type); + } + else if (existing !== unknownType) { + map.set(id, unknownType); + duplicate = true; + } + }); + if (!duplicate) count++; + } + } + } + return count >= 10 && count * 2 >= types.length ? map : undefined; + } + + // Return the name of a discriminant property for which it was possible and feasible to construct a map of + // constituent types keyed by the literal types of the property by that name in each constituent type. + function getKeyPropertyName(unionType: UnionType): __String | undefined { + const types = unionType.types; + // We only construct maps for unions with many non-primitive constituents. + if ( + types.length < 10 || getObjectFlags(unionType) & ObjectFlags.PrimitiveUnion || + countWhere(types, t => !!(t.flags & (TypeFlags.Object | TypeFlags.InstantiableNonPrimitive))) < 10 + ) { + return undefined; + } + if (unionType.keyPropertyName === undefined) { + // The candidate key property name is the name of the first property with a unit type in one of the + // constituent types. + const keyPropertyName = forEach(types, t => + t.flags & (TypeFlags.Object | TypeFlags.InstantiableNonPrimitive) ? + forEach(getPropertiesOfType(t), p => isUnitType(getTypeOfSymbol(p)) ? p.escapedName : undefined) : + undefined); + const mapByKeyProperty = keyPropertyName && mapTypesByKeyProperty(types, keyPropertyName); + unionType.keyPropertyName = mapByKeyProperty ? keyPropertyName : "" as __String; + unionType.constituentMap = mapByKeyProperty; + } + return (unionType.keyPropertyName as string).length ? unionType.keyPropertyName : undefined; + } + + // Given a union type for which getKeyPropertyName returned a non-undefined result, return the constituent + // that corresponds to the given key type for that property name. + function getConstituentTypeForKeyType(unionType: UnionType, keyType: Type) { + const result = unionType.constituentMap?.get(getTypeId(getRegularTypeOfLiteralType(keyType))); + return result !== unknownType ? result : undefined; + } + + function getMatchingUnionConstituentForType(unionType: UnionType, type: Type) { + const keyPropertyName = getKeyPropertyName(unionType); + const propType = keyPropertyName && getTypeOfPropertyOfType(type, keyPropertyName); + return propType && getConstituentTypeForKeyType(unionType, propType); + } + + function getMatchingUnionConstituentForObjectLiteral(unionType: UnionType, node: ObjectLiteralExpression) { + const keyPropertyName = getKeyPropertyName(unionType); + const propNode = keyPropertyName && find(node.properties, p => + p.symbol && p.kind === SyntaxKind.PropertyAssignment && + p.symbol.escapedName === keyPropertyName && isPossiblyDiscriminantValue(p.initializer)); + const propType = propNode && getContextFreeTypeOfExpression((propNode as PropertyAssignment).initializer); + return propType && getConstituentTypeForKeyType(unionType, propType); + } + + function isOrContainsMatchingReference(source: Node, target: Node) { + return isMatchingReference(source, target) || containsMatchingReference(source, target); + } + + function hasMatchingArgument(expression: CallExpression | NewExpression, reference: Node) { + if (expression.arguments) { + for (const argument of expression.arguments) { + if (isOrContainsMatchingReference(reference, argument) || optionalChainContainsReference(argument, reference)) { + return true; + } + } + } + if ( + expression.expression.kind === SyntaxKind.PropertyAccessExpression && + isOrContainsMatchingReference(reference, (expression.expression as PropertyAccessExpression).expression) + ) { + return true; + } + return false; + } + + function getFlowNodeId(flow: FlowNode): number { + if (flow.id <= 0) { + flow.id = nextFlowId; + nextFlowId++; + } + return flow.id; + } + + function typeMaybeAssignableTo(source: Type, target: Type) { + if (!(source.flags & TypeFlags.Union)) { + return isTypeAssignableTo(source, target); + } + for (const t of (source as UnionType).types) { + if (isTypeAssignableTo(t, target)) { + return true; + } + } + return false; + } + + // Remove those constituent types of declaredType to which no constituent type of assignedType is assignable. + // For example, when a variable of type number | string | boolean is assigned a value of type number | boolean, + // we remove type string. + function getAssignmentReducedType(declaredType: UnionType, assignedType: Type) { + if (declaredType === assignedType) { + return declaredType; + } + if (assignedType.flags & TypeFlags.Never) { + return assignedType; + } + const key = `A${getTypeId(declaredType)},${getTypeId(assignedType)}`; + return getCachedType(key) ?? setCachedType(key, getAssignmentReducedTypeWorker(declaredType, assignedType)); + } + + function getAssignmentReducedTypeWorker(declaredType: UnionType, assignedType: Type) { + const filteredType = filterType(declaredType, t => typeMaybeAssignableTo(assignedType, t)); + // Ensure that we narrow to fresh types if the assignment is a fresh boolean literal type. + const reducedType = assignedType.flags & TypeFlags.BooleanLiteral && isFreshLiteralType(assignedType) ? mapType(filteredType, getFreshTypeOfLiteralType) : filteredType; + // Our crude heuristic produces an invalid result in some cases: see GH#26130. + // For now, when that happens, we give up and don't narrow at all. (This also + // means we'll never narrow for erroneous assignments where the assigned type + // is not assignable to the declared type.) + return isTypeAssignableTo(assignedType, reducedType) ? reducedType : declaredType; + } + + function isFunctionObjectType(type: ObjectType): boolean { + // We do a quick check for a "bind" property before performing the more expensive subtype + // check. This gives us a quicker out in the common case where an object type is not a function. + const resolved = resolveStructuredTypeMembers(type); + return !!(resolved.callSignatures.length || resolved.constructSignatures.length || + resolved.members.get("bind" as __String) && isTypeSubtypeOf(type, globalFunctionType)); + } + + function getTypeFacts(type: Type, mask: TypeFacts): TypeFacts { + return getTypeFactsWorker(type, mask) & mask; + } + + function hasTypeFacts(type: Type, mask: TypeFacts): boolean { + return getTypeFacts(type, mask) !== 0; + } + + function getTypeFactsWorker(type: Type, callerOnlyNeeds: TypeFacts): TypeFacts { + if (type.flags & (TypeFlags.Intersection | TypeFlags.Instantiable)) { + type = getBaseConstraintOfType(type) || unknownType; + } + const flags = type.flags; + if (flags & (TypeFlags.String | TypeFlags.StringMapping)) { + return strictNullChecks ? TypeFacts.StringStrictFacts : TypeFacts.StringFacts; + } + if (flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral)) { + const isEmpty = flags & TypeFlags.StringLiteral && (type as StringLiteralType).value === ""; + return strictNullChecks ? + isEmpty ? TypeFacts.EmptyStringStrictFacts : TypeFacts.NonEmptyStringStrictFacts : + isEmpty ? TypeFacts.EmptyStringFacts : TypeFacts.NonEmptyStringFacts; + } + if (flags & (TypeFlags.Number | TypeFlags.Enum)) { + return strictNullChecks ? TypeFacts.NumberStrictFacts : TypeFacts.NumberFacts; + } + if (flags & TypeFlags.NumberLiteral) { + const isZero = (type as NumberLiteralType).value === 0; + return strictNullChecks ? + isZero ? TypeFacts.ZeroNumberStrictFacts : TypeFacts.NonZeroNumberStrictFacts : + isZero ? TypeFacts.ZeroNumberFacts : TypeFacts.NonZeroNumberFacts; + } + if (flags & TypeFlags.BigInt) { + return strictNullChecks ? TypeFacts.BigIntStrictFacts : TypeFacts.BigIntFacts; + } + if (flags & TypeFlags.BigIntLiteral) { + const isZero = isZeroBigInt(type as BigIntLiteralType); + return strictNullChecks ? + isZero ? TypeFacts.ZeroBigIntStrictFacts : TypeFacts.NonZeroBigIntStrictFacts : + isZero ? TypeFacts.ZeroBigIntFacts : TypeFacts.NonZeroBigIntFacts; + } + if (flags & TypeFlags.Boolean) { + return strictNullChecks ? TypeFacts.BooleanStrictFacts : TypeFacts.BooleanFacts; + } + if (flags & TypeFlags.BooleanLike) { + return strictNullChecks ? + (type === falseType || type === regularFalseType) ? TypeFacts.FalseStrictFacts : TypeFacts.TrueStrictFacts : + (type === falseType || type === regularFalseType) ? TypeFacts.FalseFacts : TypeFacts.TrueFacts; + } + if (flags & TypeFlags.Object) { + const possibleFacts = strictNullChecks + ? TypeFacts.EmptyObjectStrictFacts | TypeFacts.FunctionStrictFacts | TypeFacts.ObjectStrictFacts + : TypeFacts.EmptyObjectFacts | TypeFacts.FunctionFacts | TypeFacts.ObjectFacts; + + if ((callerOnlyNeeds & possibleFacts) === 0) { + // If the caller doesn't care about any of the facts that we could possibly produce, + // return zero so we can skip resolving members. + return 0; + } + + return getObjectFlags(type) & ObjectFlags.Anonymous && isEmptyObjectType(type as ObjectType) ? + strictNullChecks ? TypeFacts.EmptyObjectStrictFacts : TypeFacts.EmptyObjectFacts : + isFunctionObjectType(type as ObjectType) ? + strictNullChecks ? TypeFacts.FunctionStrictFacts : TypeFacts.FunctionFacts : + strictNullChecks ? TypeFacts.ObjectStrictFacts : TypeFacts.ObjectFacts; + } + if (flags & TypeFlags.Void) { + return TypeFacts.VoidFacts; + } + if (flags & TypeFlags.Undefined) { + return TypeFacts.UndefinedFacts; + } + if (flags & TypeFlags.Null) { + return TypeFacts.NullFacts; + } + if (flags & TypeFlags.ESSymbolLike) { + return strictNullChecks ? TypeFacts.SymbolStrictFacts : TypeFacts.SymbolFacts; + } + if (flags & TypeFlags.NonPrimitive) { + return strictNullChecks ? TypeFacts.ObjectStrictFacts : TypeFacts.ObjectFacts; + } + if (flags & TypeFlags.Never) { + return TypeFacts.None; + } + if (flags & TypeFlags.Union) { + return reduceLeft((type as UnionType).types, (facts, t) => facts | getTypeFactsWorker(t, callerOnlyNeeds), TypeFacts.None); + } + if (flags & TypeFlags.Intersection) { + return getIntersectionTypeFacts(type as IntersectionType, callerOnlyNeeds); + } + return TypeFacts.UnknownFacts; + } + + function getIntersectionTypeFacts(type: IntersectionType, callerOnlyNeeds: TypeFacts): TypeFacts { + // When an intersection contains a primitive type we ignore object type constituents as they are + // presumably type tags. For example, in string & { __kind__: "name" } we ignore the object type. + const ignoreObjects = maybeTypeOfKind(type, TypeFlags.Primitive); + // When computing the type facts of an intersection type, certain type facts are computed as `and` + // and others are computed as `or`. + let oredFacts = TypeFacts.None; + let andedFacts = TypeFacts.All; + for (const t of type.types) { + if (!(ignoreObjects && t.flags & TypeFlags.Object)) { + const f = getTypeFactsWorker(t, callerOnlyNeeds); + oredFacts |= f; + andedFacts &= f; + } + } + return oredFacts & TypeFacts.OrFactsMask | andedFacts & TypeFacts.AndFactsMask; + } + + function getTypeWithFacts(type: Type, include: TypeFacts) { + return filterType(type, t => hasTypeFacts(t, include)); + } + + // This function is similar to getTypeWithFacts, except that in strictNullChecks mode it replaces type + // unknown with the union {} | null | undefined (and reduces that accordingly), and it intersects remaining + // instantiable types with {}, {} | null, or {} | undefined in order to remove null and/or undefined. + function getAdjustedTypeWithFacts(type: Type, facts: TypeFacts) { + const reduced = recombineUnknownType(getTypeWithFacts(strictNullChecks && type.flags & TypeFlags.Unknown ? unknownUnionType : type, facts)); + if (strictNullChecks) { + switch (facts) { + case TypeFacts.NEUndefined: + return removeNullableByIntersection(reduced, TypeFacts.EQUndefined, TypeFacts.EQNull, TypeFacts.IsNull, nullType); + case TypeFacts.NENull: + return removeNullableByIntersection(reduced, TypeFacts.EQNull, TypeFacts.EQUndefined, TypeFacts.IsUndefined, undefinedType); + case TypeFacts.NEUndefinedOrNull: + case TypeFacts.Truthy: + return mapType(reduced, t => hasTypeFacts(t, TypeFacts.EQUndefinedOrNull) ? getGlobalNonNullableTypeInstantiation(t) : t); + } + } + return reduced; + } + + function removeNullableByIntersection(type: Type, targetFacts: TypeFacts, otherFacts: TypeFacts, otherIncludesFacts: TypeFacts, otherType: Type) { + const facts = getTypeFacts(type, TypeFacts.EQUndefined | TypeFacts.EQNull | TypeFacts.IsUndefined | TypeFacts.IsNull); + // Simply return the type if it never compares equal to the target nullable. + if (!(facts & targetFacts)) { + return type; + } + // By default we intersect with a union of {} and the opposite nullable. + const emptyAndOtherUnion = getUnionType([emptyObjectType, otherType]); + // For each constituent type that can compare equal to the target nullable, intersect with the above union + // if the type doesn't already include the opppsite nullable and the constituent can compare equal to the + // opposite nullable; otherwise, just intersect with {}. + return mapType(type, t => hasTypeFacts(t, targetFacts) ? getIntersectionType([t, !(facts & otherIncludesFacts) && hasTypeFacts(t, otherFacts) ? emptyAndOtherUnion : emptyObjectType]) : t); + } + + function recombineUnknownType(type: Type) { + return type === unknownUnionType ? unknownType : type; + } + + function getTypeWithDefault(type: Type, defaultExpression: Expression) { + return defaultExpression ? + getUnionType([getNonUndefinedType(type), getTypeOfExpression(defaultExpression)]) : + type; + } + + function getTypeOfDestructuredProperty(type: Type, name: PropertyName) { + const nameType = getLiteralTypeFromPropertyName(name); + if (!isTypeUsableAsPropertyName(nameType)) return errorType; + const text = getPropertyNameFromType(nameType); + return getTypeOfPropertyOfType(type, text) || includeUndefinedInIndexSignature(getApplicableIndexInfoForName(type, text)?.type) || errorType; + } + + function getTypeOfDestructuredArrayElement(type: Type, index: number) { + return everyType(type, isTupleLikeType) && getTupleElementType(type, index) || + includeUndefinedInIndexSignature(checkIteratedTypeOrElementType(IterationUse.Destructuring, type, undefinedType, /*errorNode*/ undefined)) || + errorType; + } + + function includeUndefinedInIndexSignature(type: Type | undefined): Type | undefined { + if (!type) return type; + return compilerOptions.noUncheckedIndexedAccess ? + getUnionType([type, missingType]) : + type; + } + + function getTypeOfDestructuredSpreadExpression(type: Type) { + return createArrayType(checkIteratedTypeOrElementType(IterationUse.Destructuring, type, undefinedType, /*errorNode*/ undefined) || errorType); + } + + function getAssignedTypeOfBinaryExpression(node: BinaryExpression): Type { + const isDestructuringDefaultAssignment = node.parent.kind === SyntaxKind.ArrayLiteralExpression && isDestructuringAssignmentTarget(node.parent) || + node.parent.kind === SyntaxKind.PropertyAssignment && isDestructuringAssignmentTarget(node.parent.parent); + return isDestructuringDefaultAssignment ? + getTypeWithDefault(getAssignedType(node), node.right) : + getTypeOfExpression(node.right); + } + + function isDestructuringAssignmentTarget(parent: Node) { + return parent.parent.kind === SyntaxKind.BinaryExpression && (parent.parent as BinaryExpression).left === parent || + parent.parent.kind === SyntaxKind.ForOfStatement && (parent.parent as ForOfStatement).initializer === parent; + } + + function getAssignedTypeOfArrayLiteralElement(node: ArrayLiteralExpression, element: Expression): Type { + return getTypeOfDestructuredArrayElement(getAssignedType(node), node.elements.indexOf(element)); + } + + function getAssignedTypeOfSpreadExpression(node: SpreadElement): Type { + return getTypeOfDestructuredSpreadExpression(getAssignedType(node.parent as ArrayLiteralExpression)); + } + + function getAssignedTypeOfPropertyAssignment(node: PropertyAssignment | ShorthandPropertyAssignment): Type { + return getTypeOfDestructuredProperty(getAssignedType(node.parent), node.name); + } + + function getAssignedTypeOfShorthandPropertyAssignment(node: ShorthandPropertyAssignment): Type { + return getTypeWithDefault(getAssignedTypeOfPropertyAssignment(node), node.objectAssignmentInitializer!); + } + + function getAssignedType(node: Expression): Type { + const { parent } = node; + switch (parent.kind) { + case SyntaxKind.ForInStatement: + return stringType; + case SyntaxKind.ForOfStatement: + return checkRightHandSideOfForOf(parent as ForOfStatement) || errorType; + case SyntaxKind.BinaryExpression: + return getAssignedTypeOfBinaryExpression(parent as BinaryExpression); + case SyntaxKind.DeleteExpression: + return undefinedType; + case SyntaxKind.ArrayLiteralExpression: + return getAssignedTypeOfArrayLiteralElement(parent as ArrayLiteralExpression, node); + case SyntaxKind.SpreadElement: + return getAssignedTypeOfSpreadExpression(parent as SpreadElement); + case SyntaxKind.PropertyAssignment: + return getAssignedTypeOfPropertyAssignment(parent as PropertyAssignment); + case SyntaxKind.ShorthandPropertyAssignment: + return getAssignedTypeOfShorthandPropertyAssignment(parent as ShorthandPropertyAssignment); + } + return errorType; + } + + function getInitialTypeOfBindingElement(node: BindingElement): Type { + const pattern = node.parent; + const parentType = getInitialType(pattern.parent as VariableDeclaration | BindingElement); + const type = pattern.kind === SyntaxKind.ObjectBindingPattern ? + getTypeOfDestructuredProperty(parentType, node.propertyName || node.name as Identifier) : + !node.dotDotDotToken ? + getTypeOfDestructuredArrayElement(parentType, pattern.elements.indexOf(node)) : + getTypeOfDestructuredSpreadExpression(parentType); + return getTypeWithDefault(type, node.initializer!); + } + + function getTypeOfInitializer(node: Expression) { + // Return the cached type if one is available. If the type of the variable was inferred + // from its initializer, we'll already have cached the type. Otherwise we compute it now + // without caching such that transient types are reflected. + const links = getNodeLinks(node); + return links.resolvedType || getTypeOfExpression(node); + } + + function getInitialTypeOfVariableDeclaration(node: VariableDeclaration) { + if (node.initializer) { + return getTypeOfInitializer(node.initializer); + } + if (node.parent.parent.kind === SyntaxKind.ForInStatement) { + return stringType; + } + if (node.parent.parent.kind === SyntaxKind.ForOfStatement) { + return checkRightHandSideOfForOf(node.parent.parent) || errorType; + } + return errorType; + } + + function getInitialType(node: VariableDeclaration | BindingElement) { + return node.kind === SyntaxKind.VariableDeclaration ? + getInitialTypeOfVariableDeclaration(node) : + getInitialTypeOfBindingElement(node); + } + + function isEmptyArrayAssignment(node: VariableDeclaration | BindingElement | Expression) { + return node.kind === SyntaxKind.VariableDeclaration && (node as VariableDeclaration).initializer && + isEmptyArrayLiteral((node as VariableDeclaration).initializer!) || + node.kind !== SyntaxKind.BindingElement && node.parent.kind === SyntaxKind.BinaryExpression && + isEmptyArrayLiteral((node.parent as BinaryExpression).right); + } + + function getReferenceCandidate(node: Expression): Expression { + switch (node.kind) { + case SyntaxKind.ParenthesizedExpression: + return getReferenceCandidate((node as ParenthesizedExpression).expression); + case SyntaxKind.BinaryExpression: + switch ((node as BinaryExpression).operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.BarBarEqualsToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: + case SyntaxKind.QuestionQuestionEqualsToken: + return getReferenceCandidate((node as BinaryExpression).left); + case SyntaxKind.CommaToken: + return getReferenceCandidate((node as BinaryExpression).right); + } + } + return node; + } + + function getReferenceRoot(node: Node): Node { + const { parent } = node; + return parent.kind === SyntaxKind.ParenthesizedExpression || + parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken && (parent as BinaryExpression).left === node || + parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.CommaToken && (parent as BinaryExpression).right === node ? + getReferenceRoot(parent) : node; + } + + function getTypeOfSwitchClause(clause: CaseClause | DefaultClause) { + if (clause.kind === SyntaxKind.CaseClause) { + return getRegularTypeOfLiteralType(getTypeOfExpression(clause.expression)); + } + return neverType; + } + + function getSwitchClauseTypes(switchStatement: SwitchStatement): Type[] { + const links = getNodeLinks(switchStatement); + if (!links.switchTypes) { + links.switchTypes = []; + for (const clause of switchStatement.caseBlock.clauses) { + links.switchTypes.push(getTypeOfSwitchClause(clause)); + } + } + return links.switchTypes; + } + + // Get the type names from all cases in a switch on `typeof`. The default clause and/or duplicate type names are + // represented as undefined. Return undefined if one or more case clause expressions are not string literals. + function getSwitchClauseTypeOfWitnesses(switchStatement: SwitchStatement): (string | undefined)[] | undefined { + if (some(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.CaseClause && !isStringLiteralLike(clause.expression))) { + return undefined; + } + const witnesses: (string | undefined)[] = []; + for (const clause of switchStatement.caseBlock.clauses) { + const text = clause.kind === SyntaxKind.CaseClause ? (clause.expression as StringLiteralLike).text : undefined; + witnesses.push(text && !contains(witnesses, text) ? text : undefined); + } + return witnesses; + } + + function eachTypeContainedIn(source: Type, types: Type[]) { + return source.flags & TypeFlags.Union ? !forEach((source as UnionType).types, t => !contains(types, t)) : contains(types, source); + } + + function isTypeSubsetOf(source: Type, target: Type) { + return !!(source === target || source.flags & TypeFlags.Never || target.flags & TypeFlags.Union && isTypeSubsetOfUnion(source, target as UnionType)); + } + + function isTypeSubsetOfUnion(source: Type, target: UnionType) { + if (source.flags & TypeFlags.Union) { + for (const t of (source as UnionType).types) { + if (!containsType(target.types, t)) { + return false; + } + } + return true; + } + if (source.flags & TypeFlags.EnumLike && getBaseTypeOfEnumLikeType(source as LiteralType) === target) { + return true; + } + return containsType(target.types, source); + } + + function forEachType(type: Type, f: (t: Type) => T | undefined): T | undefined { + return type.flags & TypeFlags.Union ? forEach((type as UnionType).types, f) : f(type); + } + + function someType(type: Type, f: (t: Type) => boolean): boolean { + return type.flags & TypeFlags.Union ? some((type as UnionType).types, f) : f(type); + } + + function everyType(type: Type, f: (t: Type) => boolean): boolean { + return type.flags & TypeFlags.Union ? every((type as UnionType).types, f) : f(type); + } + + function everyContainedType(type: Type, f: (t: Type) => boolean): boolean { + return type.flags & TypeFlags.UnionOrIntersection ? every((type as UnionOrIntersectionType).types, f) : f(type); + } + + function filterType(type: Type, f: (t: Type) => boolean): Type { + if (type.flags & TypeFlags.Union) { + const types = (type as UnionType).types; + const filtered = filter(types, f); + if (filtered === types) { + return type; + } + const origin = (type as UnionType).origin; + let newOrigin: Type | undefined; + if (origin && origin.flags & TypeFlags.Union) { + // If the origin type is a (denormalized) union type, filter its non-union constituents. If that ends + // up removing a smaller number of types than in the normalized constituent set (meaning some of the + // filtered types are within nested unions in the origin), then we can't construct a new origin type. + // Otherwise, if we have exactly one type left in the origin set, return that as the filtered type. + // Otherwise, construct a new filtered origin type. + const originTypes = (origin as UnionType).types; + const originFiltered = filter(originTypes, t => !!(t.flags & TypeFlags.Union) || f(t)); + if (originTypes.length - originFiltered.length === types.length - filtered.length) { + if (originFiltered.length === 1) { + return originFiltered[0]; + } + newOrigin = createOriginUnionOrIntersectionType(TypeFlags.Union, originFiltered); + } + } + // filtering could remove intersections so `ContainsIntersections` might be forwarded "incorrectly" + // it is purely an optimization hint so there is no harm in accidentally forwarding it + return getUnionTypeFromSortedList(filtered, (type as UnionType).objectFlags & (ObjectFlags.PrimitiveUnion | ObjectFlags.ContainsIntersections), /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined, newOrigin); + } + return type.flags & TypeFlags.Never || f(type) ? type : neverType; + } + + function removeType(type: Type, targetType: Type) { + return filterType(type, t => t !== targetType); + } + + function countTypes(type: Type) { + return type.flags & TypeFlags.Union ? (type as UnionType).types.length : 1; + } + + // Apply a mapping function to a type and return the resulting type. If the source type + // is a union type, the mapping function is applied to each constituent type and a union + // of the resulting types is returned. + function mapType(type: Type, mapper: (t: Type) => Type, noReductions?: boolean): Type; + function mapType(type: Type, mapper: (t: Type) => Type | undefined, noReductions?: boolean): Type | undefined; + function mapType(type: Type, mapper: (t: Type) => Type | undefined, noReductions?: boolean): Type | undefined { + if (type.flags & TypeFlags.Never) { + return type; + } + if (!(type.flags & TypeFlags.Union)) { + return mapper(type); + } + const origin = (type as UnionType).origin; + const types = origin && origin.flags & TypeFlags.Union ? (origin as UnionType).types : (type as UnionType).types; + let mappedTypes: Type[] | undefined; + let changed = false; + for (const t of types) { + const mapped = t.flags & TypeFlags.Union ? mapType(t, mapper, noReductions) : mapper(t); + changed ||= t !== mapped; + if (mapped) { + if (!mappedTypes) { + mappedTypes = [mapped]; + } + else { + mappedTypes.push(mapped); + } + } + } + return changed ? mappedTypes && getUnionType(mappedTypes, noReductions ? UnionReduction.None : UnionReduction.Literal) : type; + } + + function mapTypeWithAlias(type: Type, mapper: (t: Type) => Type, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { + return type.flags & TypeFlags.Union && aliasSymbol ? + getUnionType(map((type as UnionType).types, mapper), UnionReduction.Literal, aliasSymbol, aliasTypeArguments) : + mapType(type, mapper); + } + + function extractTypesOfKind(type: Type, kind: TypeFlags) { + return filterType(type, t => (t.flags & kind) !== 0); + } + + // Return a new type in which occurrences of the string, number and bigint primitives and placeholder template + // literal types in typeWithPrimitives have been replaced with occurrences of compatible and more specific types + // from typeWithLiterals. This is essentially a limited form of intersection between the two types. We avoid a + // true intersection because it is more costly and, when applied to union types, generates a large number of + // types we don't actually care about. + function replacePrimitivesWithLiterals(typeWithPrimitives: Type, typeWithLiterals: Type) { + if ( + maybeTypeOfKind(typeWithPrimitives, TypeFlags.String | TypeFlags.TemplateLiteral | TypeFlags.Number | TypeFlags.BigInt) && + maybeTypeOfKind(typeWithLiterals, TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping | TypeFlags.NumberLiteral | TypeFlags.BigIntLiteral) + ) { + return mapType(typeWithPrimitives, t => + t.flags & TypeFlags.String ? extractTypesOfKind(typeWithLiterals, TypeFlags.String | TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) : + isPatternLiteralType(t) && !maybeTypeOfKind(typeWithLiterals, TypeFlags.String | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? extractTypesOfKind(typeWithLiterals, TypeFlags.StringLiteral) : + t.flags & TypeFlags.Number ? extractTypesOfKind(typeWithLiterals, TypeFlags.Number | TypeFlags.NumberLiteral) : + t.flags & TypeFlags.BigInt ? extractTypesOfKind(typeWithLiterals, TypeFlags.BigInt | TypeFlags.BigIntLiteral) : t); + } + return typeWithPrimitives; + } + + function isIncomplete(flowType: FlowType) { + return flowType.flags === 0; + } + + function getTypeFromFlowType(flowType: FlowType) { + return flowType.flags === 0 ? flowType.type : flowType as Type; + } + + function createFlowType(type: Type, incomplete: boolean): FlowType { + return incomplete ? { flags: 0, type: type.flags & TypeFlags.Never ? silentNeverType : type } : type; + } + + // An evolving array type tracks the element types that have so far been seen in an + // 'x.push(value)' or 'x[n] = value' operation along the control flow graph. Evolving + // array types are ultimately converted into manifest array types (using getFinalArrayType) + // and never escape the getFlowTypeOfReference function. + function createEvolvingArrayType(elementType: Type): EvolvingArrayType { + const result = createObjectType(ObjectFlags.EvolvingArray) as EvolvingArrayType; + result.elementType = elementType; + return result; + } + + function getEvolvingArrayType(elementType: Type): EvolvingArrayType { + return evolvingArrayTypes[elementType.id] || (evolvingArrayTypes[elementType.id] = createEvolvingArrayType(elementType)); + } + + // When adding evolving array element types we do not perform subtype reduction. Instead, + // we defer subtype reduction until the evolving array type is finalized into a manifest + // array type. + function addEvolvingArrayElementType(evolvingArrayType: EvolvingArrayType, node: Expression): EvolvingArrayType { + const elementType = getRegularTypeOfObjectLiteral(getBaseTypeOfLiteralType(getContextFreeTypeOfExpression(node))); + return isTypeSubsetOf(elementType, evolvingArrayType.elementType) ? evolvingArrayType : getEvolvingArrayType(getUnionType([evolvingArrayType.elementType, elementType])); + } + + function createFinalArrayType(elementType: Type) { + return elementType.flags & TypeFlags.Never ? + autoArrayType : + createArrayType( + elementType.flags & TypeFlags.Union ? + getUnionType((elementType as UnionType).types, UnionReduction.Subtype) : + elementType, + ); + } + + // We perform subtype reduction upon obtaining the final array type from an evolving array type. + function getFinalArrayType(evolvingArrayType: EvolvingArrayType): Type { + return evolvingArrayType.finalArrayType || (evolvingArrayType.finalArrayType = createFinalArrayType(evolvingArrayType.elementType)); + } + + function finalizeEvolvingArrayType(type: Type): Type { + return getObjectFlags(type) & ObjectFlags.EvolvingArray ? getFinalArrayType(type as EvolvingArrayType) : type; + } + + function getElementTypeOfEvolvingArrayType(type: Type) { + return getObjectFlags(type) & ObjectFlags.EvolvingArray ? (type as EvolvingArrayType).elementType : neverType; + } + + function isEvolvingArrayTypeList(types: Type[]) { + let hasEvolvingArrayType = false; + for (const t of types) { + if (!(t.flags & TypeFlags.Never)) { + if (!(getObjectFlags(t) & ObjectFlags.EvolvingArray)) { + return false; + } + hasEvolvingArrayType = true; + } + } + return hasEvolvingArrayType; + } + + // Return true if the given node is 'x' in an 'x.length', x.push(value)', 'x.unshift(value)' or + // 'x[n] = value' operation, where 'n' is an expression of type any, undefined, or a number-like type. + function isEvolvingArrayOperationTarget(node: Node) { + const root = getReferenceRoot(node); + const parent = root.parent; + const isLengthPushOrUnshift = isPropertyAccessExpression(parent) && ( + parent.name.escapedText === "length" || + parent.parent.kind === SyntaxKind.CallExpression + && isIdentifier(parent.name) + && isPushOrUnshiftIdentifier(parent.name) + ); + const isElementAssignment = parent.kind === SyntaxKind.ElementAccessExpression && + (parent as ElementAccessExpression).expression === root && + parent.parent.kind === SyntaxKind.BinaryExpression && + (parent.parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken && + (parent.parent as BinaryExpression).left === parent && + !isAssignmentTarget(parent.parent) && + isTypeAssignableToKind(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression), TypeFlags.NumberLike); + return isLengthPushOrUnshift || isElementAssignment; + } + + function isDeclarationWithExplicitTypeAnnotation(node: Declaration) { + return (isVariableDeclaration(node) || isPropertyDeclaration(node) || isPropertySignature(node) || isParameter(node)) && + !!(getEffectiveTypeAnnotationNode(node) || + isInJSFile(node) && hasInitializer(node) && node.initializer && isFunctionExpressionOrArrowFunction(node.initializer) && getEffectiveReturnTypeNode(node.initializer)); + } + + function getExplicitTypeOfSymbol(symbol: Symbol, diagnostic?: Diagnostic) { + symbol = resolveSymbol(symbol); + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.ValueModule)) { + return getTypeOfSymbol(symbol); + } + if (symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property)) { + if (getCheckFlags(symbol) & CheckFlags.Mapped) { + const origin = (symbol as MappedSymbol).links.syntheticOrigin; + if (origin && getExplicitTypeOfSymbol(origin)) { + return getTypeOfSymbol(symbol); + } + } + const declaration = symbol.valueDeclaration; + if (declaration) { + if (isDeclarationWithExplicitTypeAnnotation(declaration)) { + return getTypeOfSymbol(symbol); + } + if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForOfStatement) { + const statement = declaration.parent.parent; + const expressionType = getTypeOfDottedName(statement.expression, /*diagnostic*/ undefined); + if (expressionType) { + const use = statement.awaitModifier ? IterationUse.ForAwaitOf : IterationUse.ForOf; + return checkIteratedTypeOrElementType(use, expressionType, undefinedType, /*errorNode*/ undefined); + } + } + if (diagnostic) { + addRelatedInfo(diagnostic, createDiagnosticForNode(declaration, Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol))); + } + } + } + } + + // We require the dotted function name in an assertion expression to be comprised of identifiers + // that reference function, method, class or value module symbols; or variable, property or + // parameter symbols with declarations that have explicit type annotations. Such references are + // resolvable with no possibility of triggering circularities in control flow analysis. + function getTypeOfDottedName(node: Expression, diagnostic: Diagnostic | undefined): Type | undefined { + if (!(node.flags & NodeFlags.InWithStatement)) { + switch (node.kind) { + case SyntaxKind.Identifier: + const symbol = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(node as Identifier)); + return getExplicitTypeOfSymbol(symbol, diagnostic); + case SyntaxKind.ThisKeyword: + return getExplicitThisType(node); + case SyntaxKind.SuperKeyword: + return checkSuperExpression(node); + case SyntaxKind.PropertyAccessExpression: { + const type = getTypeOfDottedName((node as PropertyAccessExpression).expression, diagnostic); + if (type) { + const name = (node as PropertyAccessExpression).name; + let prop: Symbol | undefined; + if (isPrivateIdentifier(name)) { + if (!type.symbol) { + return undefined; + } + prop = getPropertyOfType(type, getSymbolNameForPrivateIdentifier(type.symbol, name.escapedText)); + } + else { + prop = getPropertyOfType(type, name.escapedText); + } + return prop && getExplicitTypeOfSymbol(prop, diagnostic); + } + return undefined; + } + case SyntaxKind.ParenthesizedExpression: + return getTypeOfDottedName((node as ParenthesizedExpression).expression, diagnostic); + } + } + } + + function getEffectsSignature(node: CallExpression | InstanceofExpression) { + const links = getNodeLinks(node); + let signature = links.effectsSignature; + if (signature === undefined) { + // A call expression parented by an expression statement is a potential assertion. Other call + // expressions are potential type predicate function calls. In order to avoid triggering + // circularities in control flow analysis, we use getTypeOfDottedName when resolving the call + // target expression of an assertion. + let funcType: Type | undefined; + if (isBinaryExpression(node)) { + const rightType = checkNonNullExpression(node.right); + funcType = getSymbolHasInstanceMethodOfObjectType(rightType); + } + else if (node.parent.kind === SyntaxKind.ExpressionStatement) { + funcType = getTypeOfDottedName(node.expression, /*diagnostic*/ undefined); + } + else if (node.expression.kind !== SyntaxKind.SuperKeyword) { + if (isOptionalChain(node)) { + funcType = checkNonNullType( + getOptionalExpressionType(checkExpression(node.expression), node.expression), + node.expression, + ); + } + else { + funcType = checkNonNullExpression(node.expression); + } + } + const signatures = getSignaturesOfType(funcType && getApparentType(funcType) || unknownType, SignatureKind.Call); + const candidate = signatures.length === 1 && !signatures[0].typeParameters ? signatures[0] : + some(signatures, hasTypePredicateOrNeverReturnType) ? getResolvedSignature(node) : + undefined; + signature = links.effectsSignature = candidate && hasTypePredicateOrNeverReturnType(candidate) ? candidate : unknownSignature; + } + return signature === unknownSignature ? undefined : signature; + } + + function hasTypePredicateOrNeverReturnType(signature: Signature) { + return !!(getTypePredicateOfSignature(signature) || + signature.declaration && (getReturnTypeFromAnnotation(signature.declaration) || unknownType).flags & TypeFlags.Never); + } + + function getTypePredicateArgument(predicate: TypePredicate, callExpression: CallExpression) { + if (predicate.kind === TypePredicateKind.Identifier || predicate.kind === TypePredicateKind.AssertsIdentifier) { + return callExpression.arguments[predicate.parameterIndex]; + } + const invokedExpression = skipParentheses(callExpression.expression); + return isAccessExpression(invokedExpression) ? skipParentheses(invokedExpression.expression) : undefined; + } + + function reportFlowControlError(node: Node) { + const block = findAncestor(node, isFunctionOrModuleBlock) as Block | ModuleBlock | SourceFile; + const sourceFile = getSourceFileOfNode(node); + const span = getSpanOfTokenAtPosition(sourceFile, block.statements.pos); + diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.The_containing_function_or_module_body_is_too_large_for_control_flow_analysis)); + } + + function isReachableFlowNode(flow: FlowNode) { + const result = isReachableFlowNodeWorker(flow, /*noCacheCheck*/ false); + lastFlowNode = flow; + lastFlowNodeReachable = result; + return result; + } + + function isFalseExpression(expr: Expression): boolean { + const node = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + return node.kind === SyntaxKind.FalseKeyword || node.kind === SyntaxKind.BinaryExpression && ( + (node as BinaryExpression).operatorToken.kind === SyntaxKind.AmpersandAmpersandToken && (isFalseExpression((node as BinaryExpression).left) || isFalseExpression((node as BinaryExpression).right)) || + (node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken && isFalseExpression((node as BinaryExpression).left) && isFalseExpression((node as BinaryExpression).right) + ); + } + + function isReachableFlowNodeWorker(flow: FlowNode, noCacheCheck: boolean): boolean { + while (true) { + if (flow === lastFlowNode) { + return lastFlowNodeReachable; + } + const flags = flow.flags; + if (flags & FlowFlags.Shared) { + if (!noCacheCheck) { + const id = getFlowNodeId(flow); + const reachable = flowNodeReachable[id]; + return reachable !== undefined ? reachable : (flowNodeReachable[id] = isReachableFlowNodeWorker(flow, /*noCacheCheck*/ true)); + } + noCacheCheck = false; + } + if (flags & (FlowFlags.Assignment | FlowFlags.Condition | FlowFlags.ArrayMutation)) { + flow = (flow as FlowAssignment | FlowCondition | FlowArrayMutation).antecedent; + } + else if (flags & FlowFlags.Call) { + const signature = getEffectsSignature((flow as FlowCall).node); + if (signature) { + const predicate = getTypePredicateOfSignature(signature); + if (predicate && predicate.kind === TypePredicateKind.AssertsIdentifier && !predicate.type) { + const predicateArgument = (flow as FlowCall).node.arguments[predicate.parameterIndex]; + if (predicateArgument && isFalseExpression(predicateArgument)) { + return false; + } + } + if (getReturnTypeOfSignature(signature).flags & TypeFlags.Never) { + return false; + } + } + flow = (flow as FlowCall).antecedent; + } + else if (flags & FlowFlags.BranchLabel) { + // A branching point is reachable if any branch is reachable. + return some((flow as FlowLabel).antecedent, f => isReachableFlowNodeWorker(f, /*noCacheCheck*/ false)); + } + else if (flags & FlowFlags.LoopLabel) { + const antecedents = (flow as FlowLabel).antecedent; + if (antecedents === undefined || antecedents.length === 0) { + return false; + } + // A loop is reachable if the control flow path that leads to the top is reachable. + flow = antecedents[0]; + } + else if (flags & FlowFlags.SwitchClause) { + // The control flow path representing an unmatched value in a switch statement with + // no default clause is unreachable if the switch statement is exhaustive. + const data = (flow as FlowSwitchClause).node; + if (data.clauseStart === data.clauseEnd && isExhaustiveSwitchStatement(data.switchStatement)) { + return false; + } + flow = (flow as FlowSwitchClause).antecedent; + } + else if (flags & FlowFlags.ReduceLabel) { + // Cache is unreliable once we start adjusting labels + lastFlowNode = undefined; + const target = (flow as FlowReduceLabel).node.target; + const saveAntecedents = target.antecedent; + target.antecedent = (flow as FlowReduceLabel).node.antecedents; + const result = isReachableFlowNodeWorker((flow as FlowReduceLabel).antecedent, /*noCacheCheck*/ false); + target.antecedent = saveAntecedents; + return result; + } + else { + return !(flags & FlowFlags.Unreachable); + } + } + } + + // Return true if the given flow node is preceded by a 'super(...)' call in every possible code path + // leading to the node. + function isPostSuperFlowNode(flow: FlowNode, noCacheCheck: boolean): boolean { + while (true) { + const flags = flow.flags; + if (flags & FlowFlags.Shared) { + if (!noCacheCheck) { + const id = getFlowNodeId(flow); + const postSuper = flowNodePostSuper[id]; + return postSuper !== undefined ? postSuper : (flowNodePostSuper[id] = isPostSuperFlowNode(flow, /*noCacheCheck*/ true)); + } + noCacheCheck = false; + } + if (flags & (FlowFlags.Assignment | FlowFlags.Condition | FlowFlags.ArrayMutation | FlowFlags.SwitchClause)) { + flow = (flow as FlowAssignment | FlowCondition | FlowArrayMutation | FlowSwitchClause).antecedent; + } + else if (flags & FlowFlags.Call) { + if ((flow as FlowCall).node.expression.kind === SyntaxKind.SuperKeyword) { + return true; + } + flow = (flow as FlowCall).antecedent; + } + else if (flags & FlowFlags.BranchLabel) { + // A branching point is post-super if every branch is post-super. + return every((flow as FlowLabel).antecedent, f => isPostSuperFlowNode(f, /*noCacheCheck*/ false)); + } + else if (flags & FlowFlags.LoopLabel) { + // A loop is post-super if the control flow path that leads to the top is post-super. + flow = (flow as FlowLabel).antecedent![0]; + } + else if (flags & FlowFlags.ReduceLabel) { + const target = (flow as FlowReduceLabel).node.target; + const saveAntecedents = target.antecedent; + target.antecedent = (flow as FlowReduceLabel).node.antecedents; + const result = isPostSuperFlowNode((flow as FlowReduceLabel).antecedent, /*noCacheCheck*/ false); + target.antecedent = saveAntecedents; + return result; + } + else { + // Unreachable nodes are considered post-super to silence errors + return !!(flags & FlowFlags.Unreachable); + } + } + } + + function isConstantReference(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.ThisKeyword: + return true; + case SyntaxKind.Identifier: + if (!isThisInTypeQuery(node)) { + const symbol = getResolvedSymbol(node as Identifier); + return isConstantVariable(symbol) + || isParameterOrMutableLocalVariable(symbol) && !isSymbolAssigned(symbol) + || !!symbol.valueDeclaration && isFunctionExpression(symbol.valueDeclaration); + } + break; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + // The resolvedSymbol property is initialized by checkPropertyAccess or checkElementAccess before we get here. + return isConstantReference((node as AccessExpression).expression) && isReadonlySymbol(getNodeLinks(node).resolvedSymbol || unknownSymbol); + case SyntaxKind.ObjectBindingPattern: + case SyntaxKind.ArrayBindingPattern: + const rootDeclaration = getRootDeclaration(node.parent); + return isParameter(rootDeclaration) || isCatchClauseVariableDeclaration(rootDeclaration) + ? !isSomeSymbolAssigned(rootDeclaration) + : isVariableDeclaration(rootDeclaration) && isVarConstLike(rootDeclaration); + } + return false; + } + + function getFlowTypeOfReference(reference: Node, declaredType: Type, initialType = declaredType, flowContainer?: Node, flowNode = tryCast(reference, canHaveFlowNode)?.flowNode) { + let key: string | undefined; + let isKeySet = false; + let flowDepth = 0; + if (flowAnalysisDisabled) { + return errorType; + } + if (!flowNode) { + return declaredType; + } + flowInvocationCount++; + const sharedFlowStart = sharedFlowCount; + const evolvedType = getTypeFromFlowType(getTypeAtFlowNode(flowNode)); + sharedFlowCount = sharedFlowStart; + // When the reference is 'x' in an 'x.length', 'x.push(value)', 'x.unshift(value)' or x[n] = value' operation, + // we give type 'any[]' to 'x' instead of using the type determined by control flow analysis such that operations + // on empty arrays are possible without implicit any errors and new element types can be inferred without + // type mismatch errors. + const resultType = getObjectFlags(evolvedType) & ObjectFlags.EvolvingArray && isEvolvingArrayOperationTarget(reference) ? autoArrayType : finalizeEvolvingArrayType(evolvedType); + if (resultType === unreachableNeverType || reference.parent && reference.parent.kind === SyntaxKind.NonNullExpression && !(resultType.flags & TypeFlags.Never) && getTypeWithFacts(resultType, TypeFacts.NEUndefinedOrNull).flags & TypeFlags.Never) { + return declaredType; + } + return resultType; + + function getOrSetCacheKey() { + if (isKeySet) { + return key; + } + isKeySet = true; + return key = getFlowCacheKey(reference, declaredType, initialType, flowContainer); + } + + function getTypeAtFlowNode(flow: FlowNode): FlowType { + if (flowDepth === 2000) { + // We have made 2000 recursive invocations. To avoid overflowing the call stack we report an error + // and disable further control flow analysis in the containing function or module body. + tracing?.instant(tracing.Phase.CheckTypes, "getTypeAtFlowNode_DepthLimit", { flowId: flow.id }); + flowAnalysisDisabled = true; + reportFlowControlError(reference); + return errorType; + } + flowDepth++; + let sharedFlow: FlowNode | undefined; + while (true) { + const flags = flow.flags; + if (flags & FlowFlags.Shared) { + // We cache results of flow type resolution for shared nodes that were previously visited in + // the same getFlowTypeOfReference invocation. A node is considered shared when it is the + // antecedent of more than one node. + for (let i = sharedFlowStart; i < sharedFlowCount; i++) { + if (sharedFlowNodes[i] === flow) { + flowDepth--; + return sharedFlowTypes[i]; + } + } + sharedFlow = flow; + } + let type: FlowType | undefined; + if (flags & FlowFlags.Assignment) { + type = getTypeAtFlowAssignment(flow as FlowAssignment); + if (!type) { + flow = (flow as FlowAssignment).antecedent; + continue; + } + } + else if (flags & FlowFlags.Call) { + type = getTypeAtFlowCall(flow as FlowCall); + if (!type) { + flow = (flow as FlowCall).antecedent; + continue; + } + } + else if (flags & FlowFlags.Condition) { + type = getTypeAtFlowCondition(flow as FlowCondition); + } + else if (flags & FlowFlags.SwitchClause) { + type = getTypeAtSwitchClause(flow as FlowSwitchClause); + } + else if (flags & FlowFlags.Label) { + if ((flow as FlowLabel).antecedent!.length === 1) { + flow = (flow as FlowLabel).antecedent![0]; + continue; + } + type = flags & FlowFlags.BranchLabel ? + getTypeAtFlowBranchLabel(flow as FlowLabel) : + getTypeAtFlowLoopLabel(flow as FlowLabel); + } + else if (flags & FlowFlags.ArrayMutation) { + type = getTypeAtFlowArrayMutation(flow as FlowArrayMutation); + if (!type) { + flow = (flow as FlowArrayMutation).antecedent; + continue; + } + } + else if (flags & FlowFlags.ReduceLabel) { + const target = (flow as FlowReduceLabel).node.target; + const saveAntecedents = target.antecedent; + target.antecedent = (flow as FlowReduceLabel).node.antecedents; + type = getTypeAtFlowNode((flow as FlowReduceLabel).antecedent); + target.antecedent = saveAntecedents; + } + else if (flags & FlowFlags.Start) { + // Check if we should continue with the control flow of the containing function. + const container = (flow as FlowStart).node; + if ( + container && container !== flowContainer && + reference.kind !== SyntaxKind.PropertyAccessExpression && + reference.kind !== SyntaxKind.ElementAccessExpression && + !(reference.kind === SyntaxKind.ThisKeyword && container.kind !== SyntaxKind.ArrowFunction) + ) { + flow = container.flowNode!; + continue; + } + // At the top of the flow we have the initial type. + type = initialType; + } + else { + // Unreachable code errors are reported in the binding phase. Here we + // simply return the non-auto declared type to reduce follow-on errors. + type = convertAutoToAny(declaredType); + } + if (sharedFlow) { + // Record visited node and the associated type in the cache. + sharedFlowNodes[sharedFlowCount] = sharedFlow; + sharedFlowTypes[sharedFlowCount] = type; + sharedFlowCount++; + } + flowDepth--; + return type; + } + } + + function getInitialOrAssignedType(flow: FlowAssignment) { + const node = flow.node; + return getNarrowableTypeForReference( + node.kind === SyntaxKind.VariableDeclaration || node.kind === SyntaxKind.BindingElement ? + getInitialType(node as VariableDeclaration | BindingElement) : + getAssignedType(node), + reference, + ); + } + + function getTypeAtFlowAssignment(flow: FlowAssignment) { + const node = flow.node; + // Assignments only narrow the computed type if the declared type is a union type. Thus, we + // only need to evaluate the assigned type if the declared type is a union type. + if (isMatchingReference(reference, node)) { + if (!isReachableFlowNode(flow)) { + return unreachableNeverType; + } + if (getAssignmentTargetKind(node) === AssignmentKind.Compound) { + const flowType = getTypeAtFlowNode(flow.antecedent); + return createFlowType(getBaseTypeOfLiteralType(getTypeFromFlowType(flowType)), isIncomplete(flowType)); + } + if (declaredType === autoType || declaredType === autoArrayType) { + if (isEmptyArrayAssignment(node)) { + return getEvolvingArrayType(neverType); + } + const assignedType = getWidenedLiteralType(getInitialOrAssignedType(flow)); + return isTypeAssignableTo(assignedType, declaredType) ? assignedType : anyArrayType; + } + const t = isInCompoundLikeAssignment(node) ? getBaseTypeOfLiteralType(declaredType) : declaredType; + if (t.flags & TypeFlags.Union) { + return getAssignmentReducedType(t as UnionType, getInitialOrAssignedType(flow)); + } + return t; + } + // We didn't have a direct match. However, if the reference is a dotted name, this + // may be an assignment to a left hand part of the reference. For example, for a + // reference 'x.y.z', we may be at an assignment to 'x.y' or 'x'. In that case, + // return the declared type. + if (containsMatchingReference(reference, node)) { + if (!isReachableFlowNode(flow)) { + return unreachableNeverType; + } + // A matching dotted name might also be an expando property on a function *expression*, + // in which case we continue control flow analysis back to the function's declaration + if (isVariableDeclaration(node) && (isInJSFile(node) || isVarConstLike(node))) { + const init = getDeclaredExpandoInitializer(node); + if (init && (init.kind === SyntaxKind.FunctionExpression || init.kind === SyntaxKind.ArrowFunction)) { + return getTypeAtFlowNode(flow.antecedent); + } + } + return declaredType; + } + // for (const _ in ref) acts as a nonnull on ref + if ( + isVariableDeclaration(node) && + node.parent.parent.kind === SyntaxKind.ForInStatement && + (isMatchingReference(reference, node.parent.parent.expression) || optionalChainContainsReference(node.parent.parent.expression, reference)) + ) { + return getNonNullableTypeIfNeeded(finalizeEvolvingArrayType(getTypeFromFlowType(getTypeAtFlowNode(flow.antecedent)))); + } + // Assignment doesn't affect reference + return undefined; + } + + function narrowTypeByAssertion(type: Type, expr: Expression): Type { + const node = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + if (node.kind === SyntaxKind.FalseKeyword) { + return unreachableNeverType; + } + if (node.kind === SyntaxKind.BinaryExpression) { + if ((node as BinaryExpression).operatorToken.kind === SyntaxKind.AmpersandAmpersandToken) { + return narrowTypeByAssertion(narrowTypeByAssertion(type, (node as BinaryExpression).left), (node as BinaryExpression).right); + } + if ((node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken) { + return getUnionType([narrowTypeByAssertion(type, (node as BinaryExpression).left), narrowTypeByAssertion(type, (node as BinaryExpression).right)]); + } + } + return narrowType(type, node, /*assumeTrue*/ true); + } + + function getTypeAtFlowCall(flow: FlowCall): FlowType | undefined { + const signature = getEffectsSignature(flow.node); + if (signature) { + const predicate = getTypePredicateOfSignature(signature); + if (predicate && (predicate.kind === TypePredicateKind.AssertsThis || predicate.kind === TypePredicateKind.AssertsIdentifier)) { + const flowType = getTypeAtFlowNode(flow.antecedent); + const type = finalizeEvolvingArrayType(getTypeFromFlowType(flowType)); + const narrowedType = predicate.type ? narrowTypeByTypePredicate(type, predicate, flow.node, /*assumeTrue*/ true) : + predicate.kind === TypePredicateKind.AssertsIdentifier && predicate.parameterIndex >= 0 && predicate.parameterIndex < flow.node.arguments.length ? narrowTypeByAssertion(type, flow.node.arguments[predicate.parameterIndex]) : + type; + return narrowedType === type ? flowType : createFlowType(narrowedType, isIncomplete(flowType)); + } + if (getReturnTypeOfSignature(signature).flags & TypeFlags.Never) { + return unreachableNeverType; + } + } + return undefined; + } + + function getTypeAtFlowArrayMutation(flow: FlowArrayMutation): FlowType | undefined { + if (declaredType === autoType || declaredType === autoArrayType) { + const node = flow.node; + const expr = node.kind === SyntaxKind.CallExpression ? + (node.expression as PropertyAccessExpression).expression : + (node.left as ElementAccessExpression).expression; + if (isMatchingReference(reference, getReferenceCandidate(expr))) { + const flowType = getTypeAtFlowNode(flow.antecedent); + const type = getTypeFromFlowType(flowType); + if (getObjectFlags(type) & ObjectFlags.EvolvingArray) { + let evolvedType = type as EvolvingArrayType; + if (node.kind === SyntaxKind.CallExpression) { + for (const arg of node.arguments) { + evolvedType = addEvolvingArrayElementType(evolvedType, arg); + } + } + else { + // We must get the context free expression type so as to not recur in an uncached fashion on the LHS (which causes exponential blowup in compile time) + const indexType = getContextFreeTypeOfExpression((node.left as ElementAccessExpression).argumentExpression); + if (isTypeAssignableToKind(indexType, TypeFlags.NumberLike)) { + evolvedType = addEvolvingArrayElementType(evolvedType, node.right); + } + } + return evolvedType === type ? flowType : createFlowType(evolvedType, isIncomplete(flowType)); + } + return flowType; + } + } + return undefined; + } + + function getTypeAtFlowCondition(flow: FlowCondition): FlowType { + const flowType = getTypeAtFlowNode(flow.antecedent); + const type = getTypeFromFlowType(flowType); + if (type.flags & TypeFlags.Never) { + return flowType; + } + // If we have an antecedent type (meaning we're reachable in some way), we first + // attempt to narrow the antecedent type. If that produces the never type, and if + // the antecedent type is incomplete (i.e. a transient type in a loop), then we + // take the type guard as an indication that control *could* reach here once we + // have the complete type. We proceed by switching to the silent never type which + // doesn't report errors when operators are applied to it. Note that this is the + // *only* place a silent never type is ever generated. + const assumeTrue = (flow.flags & FlowFlags.TrueCondition) !== 0; + const nonEvolvingType = finalizeEvolvingArrayType(type); + const narrowedType = narrowType(nonEvolvingType, flow.node, assumeTrue); + if (narrowedType === nonEvolvingType) { + return flowType; + } + return createFlowType(narrowedType, isIncomplete(flowType)); + } + + function getTypeAtSwitchClause(flow: FlowSwitchClause): FlowType { + const expr = skipParentheses(flow.node.switchStatement.expression); + const flowType = getTypeAtFlowNode(flow.antecedent); + let type = getTypeFromFlowType(flowType); + if (isMatchingReference(reference, expr)) { + type = narrowTypeBySwitchOnDiscriminant(type, flow.node); + } + else if (expr.kind === SyntaxKind.TypeOfExpression && isMatchingReference(reference, (expr as TypeOfExpression).expression)) { + type = narrowTypeBySwitchOnTypeOf(type, flow.node); + } + else if (expr.kind === SyntaxKind.TrueKeyword) { + type = narrowTypeBySwitchOnTrue(type, flow.node); + } + else { + if (strictNullChecks) { + if (optionalChainContainsReference(expr, reference)) { + type = narrowTypeBySwitchOptionalChainContainment(type, flow.node, t => !(t.flags & (TypeFlags.Undefined | TypeFlags.Never))); + } + else if (expr.kind === SyntaxKind.TypeOfExpression && optionalChainContainsReference((expr as TypeOfExpression).expression, reference)) { + type = narrowTypeBySwitchOptionalChainContainment(type, flow.node, t => !(t.flags & TypeFlags.Never || t.flags & TypeFlags.StringLiteral && (t as StringLiteralType).value === "undefined")); + } + } + const access = getDiscriminantPropertyAccess(expr, type); + if (access) { + type = narrowTypeBySwitchOnDiscriminantProperty(type, access, flow.node); + } + } + return createFlowType(type, isIncomplete(flowType)); + } + + function getTypeAtFlowBranchLabel(flow: FlowLabel): FlowType { + const antecedentTypes: Type[] = []; + let subtypeReduction = false; + let seenIncomplete = false; + let bypassFlow: FlowSwitchClause | undefined; + for (const antecedent of flow.antecedent!) { + if (!bypassFlow && antecedent.flags & FlowFlags.SwitchClause && (antecedent as FlowSwitchClause).node.clauseStart === (antecedent as FlowSwitchClause).node.clauseEnd) { + // The antecedent is the bypass branch of a potentially exhaustive switch statement. + bypassFlow = antecedent as FlowSwitchClause; + continue; + } + const flowType = getTypeAtFlowNode(antecedent); + const type = getTypeFromFlowType(flowType); + // If the type at a particular antecedent path is the declared type and the + // reference is known to always be assigned (i.e. when declared and initial types + // are the same), there is no reason to process more antecedents since the only + // possible outcome is subtypes that will be removed in the final union type anyway. + if (type === declaredType && declaredType === initialType) { + return type; + } + pushIfUnique(antecedentTypes, type); + // If an antecedent type is not a subset of the declared type, we need to perform + // subtype reduction. This happens when a "foreign" type is injected into the control + // flow using the instanceof operator or a user defined type predicate. + if (!isTypeSubsetOf(type, initialType)) { + subtypeReduction = true; + } + if (isIncomplete(flowType)) { + seenIncomplete = true; + } + } + if (bypassFlow) { + const flowType = getTypeAtFlowNode(bypassFlow); + const type = getTypeFromFlowType(flowType); + // If the bypass flow contributes a type we haven't seen yet and the switch statement + // isn't exhaustive, process the bypass flow type. Since exhaustiveness checks increase + // the risk of circularities, we only want to perform them when they make a difference. + if (!(type.flags & TypeFlags.Never) && !contains(antecedentTypes, type) && !isExhaustiveSwitchStatement(bypassFlow.node.switchStatement)) { + if (type === declaredType && declaredType === initialType) { + return type; + } + antecedentTypes.push(type); + if (!isTypeSubsetOf(type, initialType)) { + subtypeReduction = true; + } + if (isIncomplete(flowType)) { + seenIncomplete = true; + } + } + } + return createFlowType(getUnionOrEvolvingArrayType(antecedentTypes, subtypeReduction ? UnionReduction.Subtype : UnionReduction.Literal), seenIncomplete); + } + + function getTypeAtFlowLoopLabel(flow: FlowLabel): FlowType { + // If we have previously computed the control flow type for the reference at + // this flow loop junction, return the cached type. + const id = getFlowNodeId(flow); + const cache = flowLoopCaches[id] || (flowLoopCaches[id] = new Map()); + const key = getOrSetCacheKey(); + if (!key) { + // No cache key is generated when binding patterns are in unnarrowable situations + return declaredType; + } + const cached = cache.get(key); + if (cached) { + return cached; + } + // If this flow loop junction and reference are already being processed, return + // the union of the types computed for each branch so far, marked as incomplete. + // It is possible to see an empty array in cases where loops are nested and the + // back edge of the outer loop reaches an inner loop that is already being analyzed. + // In such cases we restart the analysis of the inner loop, which will then see + // a non-empty in-process array for the outer loop and eventually terminate because + // the first antecedent of a loop junction is always the non-looping control flow + // path that leads to the top. + for (let i = flowLoopStart; i < flowLoopCount; i++) { + if (flowLoopNodes[i] === flow && flowLoopKeys[i] === key && flowLoopTypes[i].length) { + return createFlowType(getUnionOrEvolvingArrayType(flowLoopTypes[i], UnionReduction.Literal), /*incomplete*/ true); + } + } + // Add the flow loop junction and reference to the in-process stack and analyze + // each antecedent code path. + const antecedentTypes: Type[] = []; + let subtypeReduction = false; + let firstAntecedentType: FlowType | undefined; + for (const antecedent of flow.antecedent!) { + let flowType; + if (!firstAntecedentType) { + // The first antecedent of a loop junction is always the non-looping control + // flow path that leads to the top. + flowType = firstAntecedentType = getTypeAtFlowNode(antecedent); + } + else { + // All but the first antecedent are the looping control flow paths that lead + // back to the loop junction. We track these on the flow loop stack. + flowLoopNodes[flowLoopCount] = flow; + flowLoopKeys[flowLoopCount] = key; + flowLoopTypes[flowLoopCount] = antecedentTypes; + flowLoopCount++; + const saveFlowTypeCache = flowTypeCache; + flowTypeCache = undefined; + flowType = getTypeAtFlowNode(antecedent); + flowTypeCache = saveFlowTypeCache; + flowLoopCount--; + // If we see a value appear in the cache it is a sign that control flow analysis + // was restarted and completed by checkExpressionCached. We can simply pick up + // the resulting type and bail out. + const cached = cache.get(key); + if (cached) { + return cached; + } + } + const type = getTypeFromFlowType(flowType); + pushIfUnique(antecedentTypes, type); + // If an antecedent type is not a subset of the declared type, we need to perform + // subtype reduction. This happens when a "foreign" type is injected into the control + // flow using the instanceof operator or a user defined type predicate. + if (!isTypeSubsetOf(type, initialType)) { + subtypeReduction = true; + } + // If the type at a particular antecedent path is the declared type there is no + // reason to process more antecedents since the only possible outcome is subtypes + // that will be removed in the final union type anyway. + if (type === declaredType) { + break; + } + } + // The result is incomplete if the first antecedent (the non-looping control flow path) + // is incomplete. + const result = getUnionOrEvolvingArrayType(antecedentTypes, subtypeReduction ? UnionReduction.Subtype : UnionReduction.Literal); + if (isIncomplete(firstAntecedentType!)) { + return createFlowType(result, /*incomplete*/ true); + } + cache.set(key, result); + return result; + } + + // At flow control branch or loop junctions, if the type along every antecedent code path + // is an evolving array type, we construct a combined evolving array type. Otherwise we + // finalize all evolving array types. + function getUnionOrEvolvingArrayType(types: Type[], subtypeReduction: UnionReduction) { + if (isEvolvingArrayTypeList(types)) { + return getEvolvingArrayType(getUnionType(map(types, getElementTypeOfEvolvingArrayType))); + } + const result = recombineUnknownType(getUnionType(sameMap(types, finalizeEvolvingArrayType), subtypeReduction)); + if (result !== declaredType && result.flags & declaredType.flags & TypeFlags.Union && arraysEqual((result as UnionType).types, (declaredType as UnionType).types)) { + return declaredType; + } + return result; + } + + function getCandidateDiscriminantPropertyAccess(expr: Expression) { + if (isBindingPattern(reference) || isFunctionExpressionOrArrowFunction(reference) || isObjectLiteralMethod(reference)) { + // When the reference is a binding pattern or function or arrow expression, we are narrowing a pesudo-reference in + // getNarrowedTypeOfSymbol. An identifier for a destructuring variable declared in the same binding pattern or + // parameter declared in the same parameter list is a candidate. + if (isIdentifier(expr)) { + const symbol = getResolvedSymbol(expr); + const declaration = symbol.valueDeclaration; + if (declaration && (isBindingElement(declaration) || isParameter(declaration)) && reference === declaration.parent && !declaration.initializer && !declaration.dotDotDotToken) { + return declaration; + } + } + } + else if (isAccessExpression(expr)) { + // An access expression is a candidate if the reference matches the left hand expression. + if (isMatchingReference(reference, expr.expression)) { + return expr; + } + } + else if (isIdentifier(expr)) { + const symbol = getResolvedSymbol(expr); + if (isConstantVariable(symbol)) { + const declaration = symbol.valueDeclaration!; + // Given 'const x = obj.kind', allow 'x' as an alias for 'obj.kind' + if ( + isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && isAccessExpression(declaration.initializer) && + isMatchingReference(reference, declaration.initializer.expression) + ) { + return declaration.initializer; + } + // Given 'const { kind: x } = obj', allow 'x' as an alias for 'obj.kind' + if (isBindingElement(declaration) && !declaration.initializer) { + const parent = declaration.parent.parent; + if ( + isVariableDeclaration(parent) && !parent.type && parent.initializer && (isIdentifier(parent.initializer) || isAccessExpression(parent.initializer)) && + isMatchingReference(reference, parent.initializer) + ) { + return declaration; + } + } + } + } + return undefined; + } + + function getDiscriminantPropertyAccess(expr: Expression, computedType: Type) { + // As long as the computed type is a subset of the declared type, we use the full declared type to detect + // a discriminant property. In cases where the computed type isn't a subset, e.g because of a preceding type + // predicate narrowing, we use the actual computed type. + if (declaredType.flags & TypeFlags.Union || computedType.flags & TypeFlags.Union) { + const access = getCandidateDiscriminantPropertyAccess(expr); + if (access) { + const name = getAccessedPropertyName(access); + if (name) { + const type = declaredType.flags & TypeFlags.Union && isTypeSubsetOf(computedType, declaredType) ? declaredType : computedType; + if (isDiscriminantProperty(type, name)) { + return access; + } + } + } + } + return undefined; + } + + function narrowTypeByDiscriminant(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, narrowType: (t: Type) => Type): Type { + const propName = getAccessedPropertyName(access); + if (propName === undefined) { + return type; + } + const optionalChain = isOptionalChain(access); + const removeNullable = strictNullChecks && (optionalChain || isNonNullAccess(access)) && maybeTypeOfKind(type, TypeFlags.Nullable); + let propType = getTypeOfPropertyOfType(removeNullable ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type, propName); + if (!propType) { + return type; + } + propType = removeNullable && optionalChain ? getOptionalType(propType) : propType; + const narrowedPropType = narrowType(propType); + return filterType(type, t => { + const discriminantType = getTypeOfPropertyOrIndexSignatureOfType(t, propName) || unknownType; + return !(discriminantType.flags & TypeFlags.Never) && !(narrowedPropType.flags & TypeFlags.Never) && areTypesComparable(narrowedPropType, discriminantType); + }); + } + + function narrowTypeByDiscriminantProperty(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, operator: SyntaxKind, value: Expression, assumeTrue: boolean) { + if ((operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) && type.flags & TypeFlags.Union) { + const keyPropertyName = getKeyPropertyName(type as UnionType); + if (keyPropertyName && keyPropertyName === getAccessedPropertyName(access)) { + const candidate = getConstituentTypeForKeyType(type as UnionType, getTypeOfExpression(value)); + if (candidate) { + return operator === (assumeTrue ? SyntaxKind.EqualsEqualsEqualsToken : SyntaxKind.ExclamationEqualsEqualsToken) ? candidate : + isUnitType(getTypeOfPropertyOfType(candidate, keyPropertyName) || unknownType) ? removeType(type, candidate) : + type; + } + } + } + return narrowTypeByDiscriminant(type, access, t => narrowTypeByEquality(t, operator, value, assumeTrue)); + } + + function narrowTypeBySwitchOnDiscriminantProperty(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, data: FlowSwitchClauseData) { + if (data.clauseStart < data.clauseEnd && type.flags & TypeFlags.Union && getKeyPropertyName(type as UnionType) === getAccessedPropertyName(access)) { + const clauseTypes = getSwitchClauseTypes(data.switchStatement).slice(data.clauseStart, data.clauseEnd); + const candidate = getUnionType(map(clauseTypes, t => getConstituentTypeForKeyType(type as UnionType, t) || unknownType)); + if (candidate !== unknownType) { + return candidate; + } + } + return narrowTypeByDiscriminant(type, access, t => narrowTypeBySwitchOnDiscriminant(t, data)); + } + + function narrowTypeByTruthiness(type: Type, expr: Expression, assumeTrue: boolean): Type { + if (isMatchingReference(reference, expr)) { + return getAdjustedTypeWithFacts(type, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy); + } + if (strictNullChecks && assumeTrue && optionalChainContainsReference(expr, reference)) { + type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + const access = getDiscriminantPropertyAccess(expr, type); + if (access) { + return narrowTypeByDiscriminant(type, access, t => getTypeWithFacts(t, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy)); + } + return type; + } + + function isTypePresencePossible(type: Type, propName: __String, assumeTrue: boolean) { + const prop = getPropertyOfType(type, propName); + return prop ? + !!(prop.flags & SymbolFlags.Optional || getCheckFlags(prop) & CheckFlags.Partial) || assumeTrue : + !!getApplicableIndexInfoForName(type, propName) || !assumeTrue; + } + + function narrowTypeByInKeyword(type: Type, nameType: StringLiteralType | NumberLiteralType | UniqueESSymbolType, assumeTrue: boolean) { + const name = getPropertyNameFromType(nameType); + const isKnownProperty = someType(type, t => isTypePresencePossible(t, name, /*assumeTrue*/ true)); + if (isKnownProperty) { + // If the check is for a known property (i.e. a property declared in some constituent of + // the target type), we filter the target type by presence of absence of the property. + return filterType(type, t => isTypePresencePossible(t, name, assumeTrue)); + } + if (assumeTrue) { + // If the check is for an unknown property, we intersect the target type with `Record`, + // where X is the name of the property. + const recordSymbol = getGlobalRecordSymbol(); + if (recordSymbol) { + return getIntersectionType([type, getTypeAliasInstantiation(recordSymbol, [nameType, unknownType])]); + } + } + return type; + } + + function narrowTypeByBooleanComparison(type: Type, expr: Expression, bool: BooleanLiteral, operator: BinaryOperator, assumeTrue: boolean): Type { + assumeTrue = (assumeTrue !== (bool.kind === SyntaxKind.TrueKeyword)) !== (operator !== SyntaxKind.ExclamationEqualsEqualsToken && operator !== SyntaxKind.ExclamationEqualsToken); + return narrowType(type, expr, assumeTrue); + } + + function narrowTypeByBinaryExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type { + switch (expr.operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.BarBarEqualsToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: + case SyntaxKind.QuestionQuestionEqualsToken: + return narrowTypeByTruthiness(narrowType(type, expr.right, assumeTrue), expr.left, assumeTrue); + case SyntaxKind.EqualsEqualsToken: + case SyntaxKind.ExclamationEqualsToken: + case SyntaxKind.EqualsEqualsEqualsToken: + case SyntaxKind.ExclamationEqualsEqualsToken: + const operator = expr.operatorToken.kind; + const left = getReferenceCandidate(expr.left); + const right = getReferenceCandidate(expr.right); + if (left.kind === SyntaxKind.TypeOfExpression && isStringLiteralLike(right)) { + return narrowTypeByTypeof(type, left as TypeOfExpression, operator, right, assumeTrue); + } + if (right.kind === SyntaxKind.TypeOfExpression && isStringLiteralLike(left)) { + return narrowTypeByTypeof(type, right as TypeOfExpression, operator, left, assumeTrue); + } + if (isMatchingReference(reference, left)) { + return narrowTypeByEquality(type, operator, right, assumeTrue); + } + if (isMatchingReference(reference, right)) { + return narrowTypeByEquality(type, operator, left, assumeTrue); + } + if (strictNullChecks) { + if (optionalChainContainsReference(left, reference)) { + type = narrowTypeByOptionalChainContainment(type, operator, right, assumeTrue); + } + else if (optionalChainContainsReference(right, reference)) { + type = narrowTypeByOptionalChainContainment(type, operator, left, assumeTrue); + } + } + const leftAccess = getDiscriminantPropertyAccess(left, type); + if (leftAccess) { + return narrowTypeByDiscriminantProperty(type, leftAccess, operator, right, assumeTrue); + } + const rightAccess = getDiscriminantPropertyAccess(right, type); + if (rightAccess) { + return narrowTypeByDiscriminantProperty(type, rightAccess, operator, left, assumeTrue); + } + if (isMatchingConstructorReference(left)) { + return narrowTypeByConstructor(type, operator, right, assumeTrue); + } + if (isMatchingConstructorReference(right)) { + return narrowTypeByConstructor(type, operator, left, assumeTrue); + } + if (isBooleanLiteral(right) && !isAccessExpression(left)) { + return narrowTypeByBooleanComparison(type, left, right, operator, assumeTrue); + } + if (isBooleanLiteral(left) && !isAccessExpression(right)) { + return narrowTypeByBooleanComparison(type, right, left, operator, assumeTrue); + } + break; + case SyntaxKind.InstanceOfKeyword: + return narrowTypeByInstanceof(type, expr as InstanceofExpression, assumeTrue); + case SyntaxKind.InKeyword: + if (isPrivateIdentifier(expr.left)) { + return narrowTypeByPrivateIdentifierInInExpression(type, expr, assumeTrue); + } + const target = getReferenceCandidate(expr.right); + if (containsMissingType(type) && isAccessExpression(reference) && isMatchingReference(reference.expression, target)) { + const leftType = getTypeOfExpression(expr.left); + if (isTypeUsableAsPropertyName(leftType) && getAccessedPropertyName(reference) === getPropertyNameFromType(leftType)) { + return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined); + } + } + if (isMatchingReference(reference, target)) { + const leftType = getTypeOfExpression(expr.left); + if (isTypeUsableAsPropertyName(leftType)) { + return narrowTypeByInKeyword(type, leftType, assumeTrue); + } + } + break; + case SyntaxKind.CommaToken: + return narrowType(type, expr.right, assumeTrue); + // Ordinarily we won't see && and || expressions in control flow analysis because the Binder breaks those + // expressions down to individual conditional control flows. However, we may encounter them when analyzing + // aliased conditional expressions. + case SyntaxKind.AmpersandAmpersandToken: + return assumeTrue ? + narrowType(narrowType(type, expr.left, /*assumeTrue*/ true), expr.right, /*assumeTrue*/ true) : + getUnionType([narrowType(type, expr.left, /*assumeTrue*/ false), narrowType(type, expr.right, /*assumeTrue*/ false)]); + case SyntaxKind.BarBarToken: + return assumeTrue ? + getUnionType([narrowType(type, expr.left, /*assumeTrue*/ true), narrowType(type, expr.right, /*assumeTrue*/ true)]) : + narrowType(narrowType(type, expr.left, /*assumeTrue*/ false), expr.right, /*assumeTrue*/ false); + } + return type; + } + + function narrowTypeByPrivateIdentifierInInExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type { + const target = getReferenceCandidate(expr.right); + if (!isMatchingReference(reference, target)) { + return type; + } + + Debug.assertNode(expr.left, isPrivateIdentifier); + const symbol = getSymbolForPrivateIdentifierExpression(expr.left); + if (symbol === undefined) { + return type; + } + const classSymbol = symbol.parent!; + const targetType = hasStaticModifier(Debug.checkDefined(symbol.valueDeclaration, "should always have a declaration")) + ? getTypeOfSymbol(classSymbol) as InterfaceType + : getDeclaredTypeOfSymbol(classSymbol); + return getNarrowedType(type, targetType, assumeTrue, /*checkDerived*/ true); + } + + function narrowTypeByOptionalChainContainment(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type { + // We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows: + // When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch. + // When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch. + // When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch. + // When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch. + // When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch. + // When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch. + // When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch. + // When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch. + const equalsOperator = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken; + const nullableFlags = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken ? TypeFlags.Nullable : TypeFlags.Undefined; + const valueType = getTypeOfExpression(value); + // Note that we include any and unknown in the exclusion test because their domain includes null and undefined. + const removeNullable = equalsOperator !== assumeTrue && everyType(valueType, t => !!(t.flags & nullableFlags)) || + equalsOperator === assumeTrue && everyType(valueType, t => !(t.flags & (TypeFlags.AnyOrUnknown | nullableFlags))); + return removeNullable ? getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; + } + + function narrowTypeByEquality(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type { + if (type.flags & TypeFlags.Any) { + return type; + } + if (operator === SyntaxKind.ExclamationEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) { + assumeTrue = !assumeTrue; + } + const valueType = getTypeOfExpression(value); + const doubleEquals = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken; + if (valueType.flags & TypeFlags.Nullable) { + if (!strictNullChecks) { + return type; + } + const facts = doubleEquals ? + assumeTrue ? TypeFacts.EQUndefinedOrNull : TypeFacts.NEUndefinedOrNull : + valueType.flags & TypeFlags.Null ? + assumeTrue ? TypeFacts.EQNull : TypeFacts.NENull : + assumeTrue ? TypeFacts.EQUndefined : TypeFacts.NEUndefined; + return getAdjustedTypeWithFacts(type, facts); + } + if (assumeTrue) { + if (!doubleEquals && (type.flags & TypeFlags.Unknown || someType(type, isEmptyAnonymousObjectType))) { + if (valueType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive) || isEmptyAnonymousObjectType(valueType)) { + return valueType; + } + if (valueType.flags & TypeFlags.Object) { + return nonPrimitiveType; + } + } + const filteredType = filterType(type, t => areTypesComparable(t, valueType) || doubleEquals && isCoercibleUnderDoubleEquals(t, valueType)); + return replacePrimitivesWithLiterals(filteredType, valueType); + } + if (isUnitType(valueType)) { + return filterType(type, t => !(isUnitLikeType(t) && areTypesComparable(t, valueType))); + } + return type; + } + + function narrowTypeByTypeof(type: Type, typeOfExpr: TypeOfExpression, operator: SyntaxKind, literal: LiteralExpression, assumeTrue: boolean): Type { + // We have '==', '!=', '===', or !==' operator with 'typeof xxx' and string literal operands + if (operator === SyntaxKind.ExclamationEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) { + assumeTrue = !assumeTrue; + } + const target = getReferenceCandidate(typeOfExpr.expression); + if (!isMatchingReference(reference, target)) { + if (strictNullChecks && optionalChainContainsReference(target, reference) && assumeTrue === (literal.text !== "undefined")) { + type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + const propertyAccess = getDiscriminantPropertyAccess(target, type); + if (propertyAccess) { + return narrowTypeByDiscriminant(type, propertyAccess, t => narrowTypeByLiteralExpression(t, literal, assumeTrue)); + } + return type; + } + return narrowTypeByLiteralExpression(type, literal, assumeTrue); + } + + function narrowTypeByLiteralExpression(type: Type, literal: LiteralExpression, assumeTrue: boolean) { + return assumeTrue ? + narrowTypeByTypeName(type, literal.text) : + getAdjustedTypeWithFacts(type, typeofNEFacts.get(literal.text) || TypeFacts.TypeofNEHostObject); + } + + function narrowTypeBySwitchOptionalChainContainment(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData, clauseCheck: (type: Type) => boolean) { + const everyClauseChecks = clauseStart !== clauseEnd && every(getSwitchClauseTypes(switchStatement).slice(clauseStart, clauseEnd), clauseCheck); + return everyClauseChecks ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; + } + + function narrowTypeBySwitchOnDiscriminant(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData) { + // We only narrow if all case expressions specify + // values with unit types, except for the case where + // `type` is unknown. In this instance we map object + // types to the nonPrimitive type and narrow with that. + const switchTypes = getSwitchClauseTypes(switchStatement); + if (!switchTypes.length) { + return type; + } + const clauseTypes = switchTypes.slice(clauseStart, clauseEnd); + const hasDefaultClause = clauseStart === clauseEnd || contains(clauseTypes, neverType); + if ((type.flags & TypeFlags.Unknown) && !hasDefaultClause) { + let groundClauseTypes: Type[] | undefined; + for (let i = 0; i < clauseTypes.length; i += 1) { + const t = clauseTypes[i]; + if (t.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive)) { + if (groundClauseTypes !== undefined) { + groundClauseTypes.push(t); + } + } + else if (t.flags & TypeFlags.Object) { + if (groundClauseTypes === undefined) { + groundClauseTypes = clauseTypes.slice(0, i); + } + groundClauseTypes.push(nonPrimitiveType); + } + else { + return type; + } + } + return getUnionType(groundClauseTypes === undefined ? clauseTypes : groundClauseTypes); + } + const discriminantType = getUnionType(clauseTypes); + const caseType = discriminantType.flags & TypeFlags.Never ? neverType : + replacePrimitivesWithLiterals(filterType(type, t => areTypesComparable(discriminantType, t)), discriminantType); + if (!hasDefaultClause) { + return caseType; + } + const defaultType = filterType(type, t => !(isUnitLikeType(t) && contains(switchTypes, t.flags & TypeFlags.Undefined ? undefinedType : getRegularTypeOfLiteralType(extractUnitType(t))))); + return caseType.flags & TypeFlags.Never ? defaultType : getUnionType([caseType, defaultType]); + } + + function narrowTypeByTypeName(type: Type, typeName: string) { + switch (typeName) { + case "string": + return narrowTypeByTypeFacts(type, stringType, TypeFacts.TypeofEQString); + case "number": + return narrowTypeByTypeFacts(type, numberType, TypeFacts.TypeofEQNumber); + case "bigint": + return narrowTypeByTypeFacts(type, bigintType, TypeFacts.TypeofEQBigInt); + case "boolean": + return narrowTypeByTypeFacts(type, booleanType, TypeFacts.TypeofEQBoolean); + case "symbol": + return narrowTypeByTypeFacts(type, esSymbolType, TypeFacts.TypeofEQSymbol); + case "object": + return type.flags & TypeFlags.Any ? type : getUnionType([narrowTypeByTypeFacts(type, nonPrimitiveType, TypeFacts.TypeofEQObject), narrowTypeByTypeFacts(type, nullType, TypeFacts.EQNull)]); + case "function": + return type.flags & TypeFlags.Any ? type : narrowTypeByTypeFacts(type, globalFunctionType, TypeFacts.TypeofEQFunction); + case "undefined": + return narrowTypeByTypeFacts(type, undefinedType, TypeFacts.EQUndefined); + } + return narrowTypeByTypeFacts(type, nonPrimitiveType, TypeFacts.TypeofEQHostObject); + } + + function narrowTypeByTypeFacts(type: Type, impliedType: Type, facts: TypeFacts) { + return mapType(type, t => + // We first check if a constituent is a subtype of the implied type. If so, we either keep or eliminate + // the constituent based on its type facts. We use the strict subtype relation because it treats `object` + // as a subtype of `{}`, and we need the type facts check because function types are subtypes of `object`, + // but are classified as "function" according to `typeof`. + isTypeRelatedTo(t, impliedType, strictSubtypeRelation) ? hasTypeFacts(t, facts) ? t : neverType : + // We next check if the consituent is a supertype of the implied type. If so, we substitute the implied + // type. This handles top types like `unknown` and `{}`, and supertypes like `{ toString(): string }`. + isTypeSubtypeOf(impliedType, t) ? impliedType : + // Neither the constituent nor the implied type is a subtype of the other, however their domains may still + // overlap. For example, an unconstrained type parameter and type `string`. If the type facts indicate + // possible overlap, we form an intersection. Otherwise, we eliminate the constituent. + hasTypeFacts(t, facts) ? getIntersectionType([t, impliedType]) : + neverType); + } + + function narrowTypeBySwitchOnTypeOf(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData): Type { + const witnesses = getSwitchClauseTypeOfWitnesses(switchStatement); + if (!witnesses) { + return type; + } + // Equal start and end denotes implicit fallthrough; undefined marks explicit default clause. + const defaultIndex = findIndex(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.DefaultClause); + const hasDefaultClause = clauseStart === clauseEnd || (defaultIndex >= clauseStart && defaultIndex < clauseEnd); + if (hasDefaultClause) { + // In the default clause we filter constituents down to those that are not-equal to all handled cases. + const notEqualFacts = getNotEqualFactsFromTypeofSwitch(clauseStart, clauseEnd, witnesses); + return filterType(type, t => getTypeFacts(t, notEqualFacts) === notEqualFacts); + } + // In the non-default cause we create a union of the type narrowed by each of the listed cases. + const clauseWitnesses = witnesses.slice(clauseStart, clauseEnd); + return getUnionType(map(clauseWitnesses, text => text ? narrowTypeByTypeName(type, text) : neverType)); + } + + function narrowTypeBySwitchOnTrue(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData): Type { + const defaultIndex = findIndex(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.DefaultClause); + const hasDefaultClause = clauseStart === clauseEnd || (defaultIndex >= clauseStart && defaultIndex < clauseEnd); + + // First, narrow away all of the cases that preceded this set of cases. + for (let i = 0; i < clauseStart; i++) { + const clause = switchStatement.caseBlock.clauses[i]; + if (clause.kind === SyntaxKind.CaseClause) { + type = narrowType(type, clause.expression, /*assumeTrue*/ false); + } + } + + // If our current set has a default, then none the other cases were hit either. + // There's no point in narrowing by the the other cases in the set, since we can + // get here through other paths. + if (hasDefaultClause) { + for (let i = clauseEnd; i < switchStatement.caseBlock.clauses.length; i++) { + const clause = switchStatement.caseBlock.clauses[i]; + if (clause.kind === SyntaxKind.CaseClause) { + type = narrowType(type, clause.expression, /*assumeTrue*/ false); + } + } + return type; + } + + // Now, narrow based on the cases in this set. + const clauses = switchStatement.caseBlock.clauses.slice(clauseStart, clauseEnd); + return getUnionType(map(clauses, clause => clause.kind === SyntaxKind.CaseClause ? narrowType(type, clause.expression, /*assumeTrue*/ true) : neverType)); + } + + function isMatchingConstructorReference(expr: Expression) { + return (isPropertyAccessExpression(expr) && idText(expr.name) === "constructor" || + isElementAccessExpression(expr) && isStringLiteralLike(expr.argumentExpression) && expr.argumentExpression.text === "constructor") && + isMatchingReference(reference, expr.expression); + } + + function narrowTypeByConstructor(type: Type, operator: SyntaxKind, identifier: Expression, assumeTrue: boolean): Type { + // Do not narrow when checking inequality. + if (assumeTrue ? (operator !== SyntaxKind.EqualsEqualsToken && operator !== SyntaxKind.EqualsEqualsEqualsToken) : (operator !== SyntaxKind.ExclamationEqualsToken && operator !== SyntaxKind.ExclamationEqualsEqualsToken)) { + return type; + } + + // Get the type of the constructor identifier expression, if it is not a function then do not narrow. + const identifierType = getTypeOfExpression(identifier); + if (!isFunctionType(identifierType) && !isConstructorType(identifierType)) { + return type; + } + + // Get the prototype property of the type identifier so we can find out its type. + const prototypeProperty = getPropertyOfType(identifierType, "prototype" as __String); + if (!prototypeProperty) { + return type; + } + + // Get the type of the prototype, if it is undefined, or the global `Object` or `Function` types then do not narrow. + const prototypeType = getTypeOfSymbol(prototypeProperty); + const candidate = !isTypeAny(prototypeType) ? prototypeType : undefined; + if (!candidate || candidate === globalObjectType || candidate === globalFunctionType) { + return type; + } + + // If the type that is being narrowed is `any` then just return the `candidate` type since every type is a subtype of `any`. + if (isTypeAny(type)) { + return candidate; + } + + // Filter out types that are not considered to be "constructed by" the `candidate` type. + return filterType(type, t => isConstructedBy(t, candidate)); + + function isConstructedBy(source: Type, target: Type) { + // If either the source or target type are a class type then we need to check that they are the same exact type. + // This is because you may have a class `A` that defines some set of properties, and another class `B` + // that defines the same set of properties as class `A`, in that case they are structurally the same + // type, but when you do something like `instanceOfA.constructor === B` it will return false. + if ( + source.flags & TypeFlags.Object && getObjectFlags(source) & ObjectFlags.Class || + target.flags & TypeFlags.Object && getObjectFlags(target) & ObjectFlags.Class + ) { + return source.symbol === target.symbol; + } + + // For all other types just check that the `source` type is a subtype of the `target` type. + return isTypeSubtypeOf(source, target); + } + } + + function narrowTypeByInstanceof(type: Type, expr: InstanceofExpression, assumeTrue: boolean): Type { + const left = getReferenceCandidate(expr.left); + if (!isMatchingReference(reference, left)) { + if (assumeTrue && strictNullChecks && optionalChainContainsReference(left, reference)) { + return getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + return type; + } + const right = expr.right; + const rightType = getTypeOfExpression(right); + if (!isTypeDerivedFrom(rightType, globalObjectType)) { + return type; + } + + // if the right-hand side has an object type with a custom `[Symbol.hasInstance]` method, and that method + // has a type predicate, use the type predicate to perform narrowing. This allows normal `object` types to + // participate in `instanceof`, as per Step 2 of https://tc39.es/ecma262/#sec-instanceofoperator. + const signature = getEffectsSignature(expr); + const predicate = signature && getTypePredicateOfSignature(signature); + if (predicate && predicate.kind === TypePredicateKind.Identifier && predicate.parameterIndex === 0) { + return getNarrowedType(type, predicate.type, assumeTrue, /*checkDerived*/ true); + } + if (!isTypeDerivedFrom(rightType, globalFunctionType)) { + return type; + } + const instanceType = mapType(rightType, getInstanceType); + // Don't narrow from `any` if the target type is exactly `Object` or `Function`, and narrow + // in the false branch only if the target is a non-empty object type. + if ( + isTypeAny(type) && (instanceType === globalObjectType || instanceType === globalFunctionType) || + !assumeTrue && !(instanceType.flags & TypeFlags.Object && !isEmptyAnonymousObjectType(instanceType)) + ) { + return type; + } + return getNarrowedType(type, instanceType, assumeTrue, /*checkDerived*/ true); + } + + function getInstanceType(constructorType: Type) { + const prototypePropertyType = getTypeOfPropertyOfType(constructorType, "prototype" as __String); + if (prototypePropertyType && !isTypeAny(prototypePropertyType)) { + return prototypePropertyType; + } + const constructSignatures = getSignaturesOfType(constructorType, SignatureKind.Construct); + if (constructSignatures.length) { + return getUnionType(map(constructSignatures, signature => getReturnTypeOfSignature(getErasedSignature(signature)))); + } + // We use the empty object type to indicate we don't know the type of objects created by + // this constructor function. + return emptyObjectType; + } + + function getNarrowedType(type: Type, candidate: Type, assumeTrue: boolean, checkDerived: boolean): Type { + const key = type.flags & TypeFlags.Union ? `N${getTypeId(type)},${getTypeId(candidate)},${(assumeTrue ? 1 : 0) | (checkDerived ? 2 : 0)}` : undefined; + return getCachedType(key) ?? setCachedType(key, getNarrowedTypeWorker(type, candidate, assumeTrue, checkDerived)); + } + + function getNarrowedTypeWorker(type: Type, candidate: Type, assumeTrue: boolean, checkDerived: boolean) { + if (!assumeTrue) { + if (type === candidate) { + return neverType; + } + if (checkDerived) { + return filterType(type, t => !isTypeDerivedFrom(t, candidate)); + } + const trueType = getNarrowedType(type, candidate, /*assumeTrue*/ true, /*checkDerived*/ false); + return filterType(type, t => !isTypeSubsetOf(t, trueType)); + } + if (type.flags & TypeFlags.AnyOrUnknown) { + return candidate; + } + if (type === candidate) { + return candidate; + } + + // We first attempt to filter the current type, narrowing constituents as appropriate and removing + // constituents that are unrelated to the candidate. + const isRelated = checkDerived ? isTypeDerivedFrom : isTypeSubtypeOf; + const keyPropertyName = type.flags & TypeFlags.Union ? getKeyPropertyName(type as UnionType) : undefined; + const narrowedType = mapType(candidate, c => { + // If a discriminant property is available, use that to reduce the type. + const discriminant = keyPropertyName && getTypeOfPropertyOfType(c, keyPropertyName); + const matching = discriminant && getConstituentTypeForKeyType(type as UnionType, discriminant); + // For each constituent t in the current type, if t and and c are directly related, pick the most + // specific of the two. When t and c are related in both directions, we prefer c for type predicates + // because that is the asserted type, but t for `instanceof` because generics aren't reflected in + // prototype object types. + const directlyRelated = mapType( + matching || type, + checkDerived ? + t => isTypeDerivedFrom(t, c) ? t : isTypeDerivedFrom(c, t) ? c : neverType : + t => isTypeStrictSubtypeOf(t, c) ? t : isTypeStrictSubtypeOf(c, t) ? c : isTypeSubtypeOf(t, c) ? t : isTypeSubtypeOf(c, t) ? c : neverType, + ); + // If no constituents are directly related, create intersections for any generic constituents that + // are related by constraint. + return directlyRelated.flags & TypeFlags.Never ? + mapType(type, t => maybeTypeOfKind(t, TypeFlags.Instantiable) && isRelated(c, getBaseConstraintOfType(t) || unknownType) ? getIntersectionType([t, c]) : neverType) : + directlyRelated; + }); + // If filtering produced a non-empty type, return that. Otherwise, pick the most specific of the two + // based on assignability, or as a last resort produce an intersection. + return !(narrowedType.flags & TypeFlags.Never) ? narrowedType : + isTypeSubtypeOf(candidate, type) ? candidate : + isTypeAssignableTo(type, candidate) ? type : + isTypeAssignableTo(candidate, type) ? candidate : + getIntersectionType([type, candidate]); + } + + function narrowTypeByCallExpression(type: Type, callExpression: CallExpression, assumeTrue: boolean): Type { + if (hasMatchingArgument(callExpression, reference)) { + const signature = assumeTrue || !isCallChain(callExpression) ? getEffectsSignature(callExpression) : undefined; + const predicate = signature && getTypePredicateOfSignature(signature); + if (predicate && (predicate.kind === TypePredicateKind.This || predicate.kind === TypePredicateKind.Identifier)) { + return narrowTypeByTypePredicate(type, predicate, callExpression, assumeTrue); + } + } + if (containsMissingType(type) && isAccessExpression(reference) && isPropertyAccessExpression(callExpression.expression)) { + const callAccess = callExpression.expression; + if ( + isMatchingReference(reference.expression, getReferenceCandidate(callAccess.expression)) && + isIdentifier(callAccess.name) && callAccess.name.escapedText === "hasOwnProperty" && callExpression.arguments.length === 1 + ) { + const argument = callExpression.arguments[0]; + if (isStringLiteralLike(argument) && getAccessedPropertyName(reference) === escapeLeadingUnderscores(argument.text)) { + return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined); + } + } + } + return type; + } + + function narrowTypeByTypePredicate(type: Type, predicate: TypePredicate, callExpression: CallExpression, assumeTrue: boolean): Type { + // Don't narrow from 'any' if the predicate type is exactly 'Object' or 'Function' + if (predicate.type && !(isTypeAny(type) && (predicate.type === globalObjectType || predicate.type === globalFunctionType))) { + const predicateArgument = getTypePredicateArgument(predicate, callExpression); + if (predicateArgument) { + if (isMatchingReference(reference, predicateArgument)) { + return getNarrowedType(type, predicate.type, assumeTrue, /*checkDerived*/ false); + } + if ( + strictNullChecks && optionalChainContainsReference(predicateArgument, reference) && + ( + assumeTrue && !(hasTypeFacts(predicate.type, TypeFacts.EQUndefined)) || + !assumeTrue && everyType(predicate.type, isNullableType) + ) + ) { + type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + const access = getDiscriminantPropertyAccess(predicateArgument, type); + if (access) { + return narrowTypeByDiscriminant(type, access, t => getNarrowedType(t, predicate.type!, assumeTrue, /*checkDerived*/ false)); + } + } + } + return type; + } + + // Narrow the given type based on the given expression having the assumed boolean value. The returned type + // will be a subtype or the same type as the argument. + function narrowType(type: Type, expr: Expression, assumeTrue: boolean): Type { + // for `a?.b`, we emulate a synthetic `a !== null && a !== undefined` condition for `a` + if ( + isExpressionOfOptionalChainRoot(expr) || + isBinaryExpression(expr.parent) && (expr.parent.operatorToken.kind === SyntaxKind.QuestionQuestionToken || expr.parent.operatorToken.kind === SyntaxKind.QuestionQuestionEqualsToken) && expr.parent.left === expr + ) { + return narrowTypeByOptionality(type, expr, assumeTrue); + } + switch (expr.kind) { + case SyntaxKind.Identifier: + // When narrowing a reference to a const variable, non-assigned parameter, or readonly property, we inline + // up to five levels of aliased conditional expressions that are themselves declared as const variables. + if (!isMatchingReference(reference, expr) && inlineLevel < 5) { + const symbol = getResolvedSymbol(expr as Identifier); + if (isConstantVariable(symbol)) { + const declaration = symbol.valueDeclaration; + if (declaration && isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && isConstantReference(reference)) { + inlineLevel++; + const result = narrowType(type, declaration.initializer, assumeTrue); + inlineLevel--; + return result; + } + } + } + // falls through + case SyntaxKind.ThisKeyword: + case SyntaxKind.SuperKeyword: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + return narrowTypeByTruthiness(type, expr, assumeTrue); + case SyntaxKind.CallExpression: + return narrowTypeByCallExpression(type, expr as CallExpression, assumeTrue); + case SyntaxKind.ParenthesizedExpression: + case SyntaxKind.NonNullExpression: + return narrowType(type, (expr as ParenthesizedExpression | NonNullExpression).expression, assumeTrue); + case SyntaxKind.BinaryExpression: + return narrowTypeByBinaryExpression(type, expr as BinaryExpression, assumeTrue); + case SyntaxKind.PrefixUnaryExpression: + if ((expr as PrefixUnaryExpression).operator === SyntaxKind.ExclamationToken) { + return narrowType(type, (expr as PrefixUnaryExpression).operand, !assumeTrue); + } + break; + } + return type; + } + + function narrowTypeByOptionality(type: Type, expr: Expression, assumePresent: boolean): Type { + if (isMatchingReference(reference, expr)) { + return getAdjustedTypeWithFacts(type, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull); + } + const access = getDiscriminantPropertyAccess(expr, type); + if (access) { + return narrowTypeByDiscriminant(type, access, t => getTypeWithFacts(t, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull)); + } + return type; + } + } + + function getTypeOfSymbolAtLocation(symbol: Symbol, location: Node) { + symbol = getExportSymbolOfValueSymbolIfExported(symbol); + + // If we have an identifier or a property access at the given location, if the location is + // an dotted name expression, and if the location is not an assignment target, obtain the type + // of the expression (which will reflect control flow analysis). If the expression indeed + // resolved to the given symbol, return the narrowed type. + if (location.kind === SyntaxKind.Identifier || location.kind === SyntaxKind.PrivateIdentifier) { + if (isRightSideOfQualifiedNameOrPropertyAccess(location)) { + location = location.parent; + } + if (isExpressionNode(location) && (!isAssignmentTarget(location) || isWriteAccess(location))) { + const type = removeOptionalTypeMarker( + isWriteAccess(location) && location.kind === SyntaxKind.PropertyAccessExpression ? + checkPropertyAccessExpression(location as PropertyAccessExpression, /*checkMode*/ undefined, /*writeOnly*/ true) : + getTypeOfExpression(location as Expression), + ); + if (getExportSymbolOfValueSymbolIfExported(getNodeLinks(location).resolvedSymbol) === symbol) { + return type; + } + } + } + if (isDeclarationName(location) && isSetAccessor(location.parent) && getAnnotatedAccessorTypeNode(location.parent)) { + return getWriteTypeOfAccessors(location.parent.symbol); + } + // The location isn't a reference to the given symbol, meaning we're being asked + // a hypothetical question of what type the symbol would have if there was a reference + // to it at the given location. Since we have no control flow information for the + // hypothetical reference (control flow information is created and attached by the + // binder), we simply return the declared type of the symbol. + return isRightSideOfAccessExpression(location) && isWriteAccess(location.parent) ? getWriteTypeOfSymbol(symbol) : getNonMissingTypeOfSymbol(symbol); + } + + function getControlFlowContainer(node: Node): Node { + return findAncestor(node.parent, node => + isFunctionLike(node) && !getImmediatelyInvokedFunctionExpression(node) || + node.kind === SyntaxKind.ModuleBlock || + node.kind === SyntaxKind.SourceFile || + node.kind === SyntaxKind.PropertyDeclaration)!; + } + + // Check if a parameter or catch variable is assigned anywhere + function isSymbolAssigned(symbol: Symbol) { + return !isPastLastAssignment(symbol, /*location*/ undefined); + } + + // Return true if there are no assignments to the given symbol or if the given location + // is past the last assignment to the symbol. + function isPastLastAssignment(symbol: Symbol, location: Node | undefined) { + const parent = findAncestor(symbol.valueDeclaration, isFunctionOrSourceFile); + if (!parent) { + return false; + } + const links = getNodeLinks(parent); + if (!(links.flags & NodeCheckFlags.AssignmentsMarked)) { + links.flags |= NodeCheckFlags.AssignmentsMarked; + if (!hasParentWithAssignmentsMarked(parent)) { + markNodeAssignments(parent); + } + } + return !symbol.lastAssignmentPos || location && symbol.lastAssignmentPos < location.pos; + } + + // Check if a parameter or catch variable (or their bindings elements) is assigned anywhere + function isSomeSymbolAssigned(rootDeclaration: Node) { + Debug.assert(isVariableDeclaration(rootDeclaration) || isParameter(rootDeclaration)); + return isSomeSymbolAssignedWorker(rootDeclaration.name); + } + + function isSomeSymbolAssignedWorker(node: BindingName): boolean { + if (node.kind === SyntaxKind.Identifier) { + return isSymbolAssigned(getSymbolOfDeclaration(node.parent as Declaration)); + } + + return some(node.elements, e => e.kind !== SyntaxKind.OmittedExpression && isSomeSymbolAssignedWorker(e.name)); + } + + function hasParentWithAssignmentsMarked(node: Node) { + return !!findAncestor(node.parent, node => isFunctionOrSourceFile(node) && !!(getNodeLinks(node).flags & NodeCheckFlags.AssignmentsMarked)); + } + + function isFunctionOrSourceFile(node: Node) { + return isFunctionLikeDeclaration(node) || isSourceFile(node); + } + + // For all assignments within the given root node, record the last assignment source position for all + // referenced parameters and mutable local variables. When assignments occur in nested functions or + // references occur in export specifiers, record Number.MAX_VALUE as the assignment position. When + // assignments occur in compound statements, record the ending source position of the compound statement + // as the assignment position (this is more conservative than full control flow analysis, but requires + // only a single walk over the AST). + function markNodeAssignments(node: Node) { + switch (node.kind) { + case SyntaxKind.Identifier: + if (isAssignmentTarget(node)) { + const symbol = getResolvedSymbol(node as Identifier); + if (isParameterOrMutableLocalVariable(symbol) && symbol.lastAssignmentPos !== Number.MAX_VALUE) { + const referencingFunction = findAncestor(node, isFunctionOrSourceFile); + const declaringFunction = findAncestor(symbol.valueDeclaration, isFunctionOrSourceFile); + symbol.lastAssignmentPos = referencingFunction === declaringFunction ? extendAssignmentPosition(node, symbol.valueDeclaration!) : Number.MAX_VALUE; + } + } + return; + case SyntaxKind.ExportSpecifier: + const exportDeclaration = (node as ExportSpecifier).parent.parent; + const name = (node as ExportSpecifier).propertyName || (node as ExportSpecifier).name; + if (!(node as ExportSpecifier).isTypeOnly && !exportDeclaration.isTypeOnly && !exportDeclaration.moduleSpecifier && name.kind !== SyntaxKind.StringLiteral) { + const symbol = resolveEntityName(name, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ true); + if (symbol && isParameterOrMutableLocalVariable(symbol)) { + symbol.lastAssignmentPos = Number.MAX_VALUE; + } + } + return; + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.EnumDeclaration: + return; + } + if (isTypeNode(node)) { + return; + } + forEachChild(node, markNodeAssignments); + } + + // Extend the position of the given assignment target node to the end of any intervening variable statement, + // expression statement, compound statement, or class declaration occurring between the node and the given + // declaration node. + function extendAssignmentPosition(node: Node, declaration: Declaration) { + let pos = node.pos; + while (node && node.pos > declaration.pos) { + switch (node.kind) { + case SyntaxKind.VariableStatement: + case SyntaxKind.ExpressionStatement: + case SyntaxKind.IfStatement: + case SyntaxKind.DoStatement: + case SyntaxKind.WhileStatement: + case SyntaxKind.ForStatement: + case SyntaxKind.ForInStatement: + case SyntaxKind.ForOfStatement: + case SyntaxKind.WithStatement: + case SyntaxKind.SwitchStatement: + case SyntaxKind.TryStatement: + case SyntaxKind.ClassDeclaration: + pos = node.end; + } + node = node.parent; + } + return pos; + } + + function isConstantVariable(symbol: Symbol) { + return symbol.flags & SymbolFlags.Variable && (getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Constant) !== 0; + } + + function isParameterOrMutableLocalVariable(symbol: Symbol) { + // Return true if symbol is a parameter, a catch clause variable, or a mutable local variable + const declaration = symbol.valueDeclaration && getRootDeclaration(symbol.valueDeclaration); + return !!declaration && ( + isParameter(declaration) || + isVariableDeclaration(declaration) && (isCatchClause(declaration.parent) || isMutableLocalVariableDeclaration(declaration)) + ); + } + + function isMutableLocalVariableDeclaration(declaration: VariableDeclaration) { + // Return true if symbol is a non-exported and non-global `let` variable + return !!(declaration.parent.flags & NodeFlags.Let) && !( + getCombinedModifierFlags(declaration) & ModifierFlags.Export || + declaration.parent.parent.kind === SyntaxKind.VariableStatement && isGlobalSourceFile(declaration.parent.parent.parent) + ); + } + + function parameterInitializerContainsUndefined(declaration: ParameterDeclaration): boolean { + const links = getNodeLinks(declaration); + + if (links.parameterInitializerContainsUndefined === undefined) { + if (!pushTypeResolution(declaration, TypeSystemPropertyName.ParameterInitializerContainsUndefined)) { + reportCircularityError(declaration.symbol); + return true; + } + + const containsUndefined = !!(hasTypeFacts(checkDeclarationInitializer(declaration, CheckMode.Normal), TypeFacts.IsUndefined)); + + if (!popTypeResolution()) { + reportCircularityError(declaration.symbol); + return true; + } + + links.parameterInitializerContainsUndefined ??= containsUndefined; + } + + return links.parameterInitializerContainsUndefined; + } + + /** remove undefined from the annotated type of a parameter when there is an initializer (that doesn't include undefined) */ + function removeOptionalityFromDeclaredType(declaredType: Type, declaration: VariableLikeDeclaration): Type { + const removeUndefined = strictNullChecks && + declaration.kind === SyntaxKind.Parameter && + declaration.initializer && + hasTypeFacts(declaredType, TypeFacts.IsUndefined) && + !parameterInitializerContainsUndefined(declaration); + + return removeUndefined ? getTypeWithFacts(declaredType, TypeFacts.NEUndefined) : declaredType; + } + + function isConstraintPosition(type: Type, node: Node) { + const parent = node.parent; + // In an element access obj[x], we consider obj to be in a constraint position, except when obj is of + // a generic type without a nullable constraint and x is a generic type. This is because when both obj + // and x are of generic types T and K, we want the resulting type to be T[K]. + return parent.kind === SyntaxKind.PropertyAccessExpression || + parent.kind === SyntaxKind.QualifiedName || + parent.kind === SyntaxKind.CallExpression && (parent as CallExpression).expression === node || + parent.kind === SyntaxKind.NewExpression && (parent as NewExpression).expression === node || + parent.kind === SyntaxKind.ElementAccessExpression && (parent as ElementAccessExpression).expression === node && + !(someType(type, isGenericTypeWithoutNullableConstraint) && isGenericIndexType(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression))); + } + + function isGenericTypeWithUnionConstraint(type: Type): boolean { + return type.flags & TypeFlags.Intersection ? + some((type as IntersectionType).types, isGenericTypeWithUnionConstraint) : + !!(type.flags & TypeFlags.Instantiable && getBaseConstraintOrType(type).flags & (TypeFlags.Nullable | TypeFlags.Union)); + } + + function isGenericTypeWithoutNullableConstraint(type: Type): boolean { + return type.flags & TypeFlags.Intersection ? + some((type as IntersectionType).types, isGenericTypeWithoutNullableConstraint) : + !!(type.flags & TypeFlags.Instantiable && !maybeTypeOfKind(getBaseConstraintOrType(type), TypeFlags.Nullable)); + } + + function hasContextualTypeWithNoGenericTypes(node: Node, checkMode: CheckMode | undefined) { + // Computing the contextual type for a child of a JSX element involves resolving the type of the + // element's tag name, so we exclude that here to avoid circularities. + // If check mode has `CheckMode.RestBindingElement`, we skip binding pattern contextual types, + // as we want the type of a rest element to be generic when possible. + const contextualType = (isIdentifier(node) || isPropertyAccessExpression(node) || isElementAccessExpression(node)) && + !((isJsxOpeningElement(node.parent) || isJsxSelfClosingElement(node.parent)) && node.parent.tagName === node) && + (checkMode && checkMode & CheckMode.RestBindingElement ? + getContextualType(node, ContextFlags.SkipBindingPatterns) + : getContextualType(node, /*contextFlags*/ undefined)); + return contextualType && !isGenericType(contextualType); + } + + function getNarrowableTypeForReference(type: Type, reference: Node, checkMode?: CheckMode) { + if (isNoInferType(type)) { + type = (type as SubstitutionType).baseType; + } + // When the type of a reference is or contains an instantiable type with a union type constraint, and + // when the reference is in a constraint position (where it is known we'll obtain the apparent type) or + // has a contextual type containing no top-level instantiables (meaning constraints will determine + // assignability), we substitute constraints for all instantiables in the type of the reference to give + // control flow analysis an opportunity to narrow it further. For example, for a reference of a type + // parameter type 'T extends string | undefined' with a contextual type 'string', we substitute + // 'string | undefined' to give control flow analysis the opportunity to narrow to type 'string'. + const substituteConstraints = !(checkMode && checkMode & CheckMode.Inferential) && + someType(type, isGenericTypeWithUnionConstraint) && + (isConstraintPosition(type, reference) || hasContextualTypeWithNoGenericTypes(reference, checkMode)); + return substituteConstraints ? mapType(type, getBaseConstraintOrType) : type; + } + + function isExportOrExportExpression(location: Node) { + return !!findAncestor(location, n => { + const parent = n.parent; + if (parent === undefined) { + return "quit"; + } + if (isExportAssignment(parent)) { + return parent.expression === n && isEntityNameExpression(n); + } + if (isExportSpecifier(parent)) { + return parent.name === n || parent.propertyName === n; + } + return false; + }); + } + + /** + * This function marks all the imports the given location refers to as `.referenced` in `NodeLinks` (transitively through local import aliases). + * (This corresponds to not getting elided in JS emit.) + * It can be called on *most* nodes in the AST with `ReferenceHint.Unspecified` and will filter its inputs, but care should be taken to avoid calling it on the RHS of an `import =` or specifiers in a `import {} from "..."`, + * unless you *really* want to *definitely* mark those as referenced. + * These shouldn't be directly marked, and should only get marked transitively by the internals of this function. + * + * @param location The location to mark js import refernces for + * @param hint The kind of reference `location` has already been checked to be + * @param propSymbol The optional symbol of the property we're looking up - this is used for property accesses when `const enum`s do not count as references (no `isolatedModules`, no `preserveConstEnums` + export). It will be calculated if not provided. + * @param parentType The optional type of the parent of the LHS of the property access - this will be recalculated if not provided (but is costly). + */ + function markLinkedReferences(location: PropertyAccessExpression | QualifiedName, hint: ReferenceHint.Property, propSymbol: Symbol | undefined, parentType: Type): void; + function markLinkedReferences(location: Identifier, hint: ReferenceHint.Identifier): void; + function markLinkedReferences(location: ExportAssignment, hint: ReferenceHint.ExportAssignment): void; + function markLinkedReferences(location: JsxOpeningLikeElement | JsxOpeningFragment, hint: ReferenceHint.Jsx): void; + function markLinkedReferences(location: FunctionLikeDeclaration | MethodSignature, hint: ReferenceHint.AsyncFunction): void; + function markLinkedReferences(location: ImportEqualsDeclaration, hint: ReferenceHint.ExportImportEquals): void; + function markLinkedReferences(location: ExportSpecifier, hint: ReferenceHint.ExportSpecifier): void; + function markLinkedReferences(location: HasDecorators, hint: ReferenceHint.Decorator): void; + function markLinkedReferences(location: Node, hint: ReferenceHint.Unspecified, propSymbol?: Symbol, parentType?: Type): void; + function markLinkedReferences(location: Node, hint: ReferenceHint, propSymbol?: Symbol, parentType?: Type) { + if (!canCollectSymbolAliasAccessabilityData) { + return; + } + if (location.flags & NodeFlags.Ambient) { + return; // References within types and declaration files are never going to contribute to retaining a JS import + } + switch (hint) { + case ReferenceHint.Identifier: + return markIdentifierAliasReferenced(location as Identifier); + case ReferenceHint.Property: + return markPropertyAliasReferenced(location as PropertyAccessExpression | QualifiedName, propSymbol, parentType); + case ReferenceHint.ExportAssignment: + return markExportAssignmentAliasReferenced(location as ExportAssignment); + case ReferenceHint.Jsx: + return markJsxAliasReferenced(location as JsxOpeningLikeElement | JsxOpeningFragment); + case ReferenceHint.AsyncFunction: + return markAsyncFunctionAliasReferenced(location as FunctionLikeDeclaration | MethodSignature); + case ReferenceHint.ExportImportEquals: + return markImportEqualsAliasReferenced(location as ImportEqualsDeclaration); + case ReferenceHint.ExportSpecifier: + return markExportSpecifierAliasReferenced(location as ExportSpecifier); + case ReferenceHint.Decorator: + return markDecoratorAliasReferenced(location as HasDecorators); + case ReferenceHint.Unspecified: { + // Identifiers in expression contexts are emitted, so we need to follow their referenced aliases and mark them as used + // Some non-expression identifiers are also treated as expression identifiers for this purpose, eg, `a` in `b = {a}` or `q` in `import r = q` + // This is the exception, rather than the rule - most non-expression identifiers are declaration names. + if (isIdentifier(location) && (isExpressionNode(location) || isShorthandPropertyAssignment(location.parent) || (isImportEqualsDeclaration(location.parent) && location.parent.moduleReference === location)) && shouldMarkIdentifierAliasReferenced(location)) { + if (isPropertyAccessOrQualifiedName(location.parent)) { + const left = isPropertyAccessExpression(location.parent) ? location.parent.expression : location.parent.left; + if (left !== location) return; // Only mark the LHS (the RHS is a property lookup) + } + markIdentifierAliasReferenced(location); + return; + } + if (isPropertyAccessOrQualifiedName(location)) { + let topProp: Node | undefined = location; + while (isPropertyAccessOrQualifiedName(topProp)) { + if (isPartOfTypeNode(topProp)) return; + topProp = topProp.parent; + } + return markPropertyAliasReferenced(location); + } + if (isExportAssignment(location)) { + return markExportAssignmentAliasReferenced(location); + } + if (isJsxOpeningLikeElement(location) || isJsxOpeningFragment(location)) { + return markJsxAliasReferenced(location); + } + if (isImportEqualsDeclaration(location)) { + if (isInternalModuleImportEqualsDeclaration(location) || checkExternalImportOrExportDeclaration(location)) { + return markImportEqualsAliasReferenced(location); + } + return; + } + if (isExportSpecifier(location)) { + return markExportSpecifierAliasReferenced(location); + } + if (isFunctionLikeDeclaration(location) || isMethodSignature(location)) { + markAsyncFunctionAliasReferenced(location); + // Might be decorated, fall through to decorator final case + } + if (!compilerOptions.emitDecoratorMetadata) { + return; + } + if (!canHaveDecorators(location) || !hasDecorators(location) || !location.modifiers || !nodeCanBeDecorated(legacyDecorators, location, location.parent, location.parent.parent)) { + return; + } + + return markDecoratorAliasReferenced(location); + } + default: + Debug.assertNever(hint, `Unhandled reference hint: ${hint}`); + } + } + + function markIdentifierAliasReferenced(location: Identifier) { + const symbol = getResolvedSymbol(location); + if (symbol && symbol !== argumentsSymbol && symbol !== unknownSymbol && !isThisInTypeQuery(location)) { + markAliasReferenced(symbol, location); + } + } + + function markPropertyAliasReferenced(location: PropertyAccessExpression | QualifiedName, propSymbol?: Symbol, parentType?: Type) { + const left = isPropertyAccessExpression(location) ? location.expression : location.left; + if (isThisIdentifier(left) || !isIdentifier(left)) { + return; + } + const parentSymbol = getResolvedSymbol(left); + if (!parentSymbol || parentSymbol === unknownSymbol) { + return; + } + // In `Foo.Bar.Baz`, 'Foo' is not referenced if 'Bar' is a const enum or a module containing only const enums. + // `Foo` is also not referenced in `enum FooCopy { Bar = Foo.Bar }`, because the enum member value gets inlined + // here even if `Foo` is not a const enum. + // + // The exceptions are: + // 1. if 'isolatedModules' is enabled, because the const enum value will not be inlined, and + // 2. if 'preserveConstEnums' is enabled and the expression is itself an export, e.g. `export = Foo.Bar.Baz`. + // + // The property lookup is deferred as much as possible, in as many situations as possible, to avoid alias marking + // pulling on types/symbols it doesn't strictly need to. + if (getIsolatedModules(compilerOptions) || (shouldPreserveConstEnums(compilerOptions) && isExportOrExportExpression(location))) { + markAliasReferenced(parentSymbol, location); + return; + } + // Hereafter, this relies on type checking - but every check prior to this only used symbol information + const leftType = parentType || checkExpressionCached(left); + if (isTypeAny(leftType) || leftType === silentNeverType) { + markAliasReferenced(parentSymbol, location); + return; + } + let prop = propSymbol; + if (!prop && !parentType) { + const right = isPropertyAccessExpression(location) ? location.name : location.right; + const lexicallyScopedSymbol = isPrivateIdentifier(right) && lookupSymbolForPrivateIdentifierDeclaration(right.escapedText, right); + const assignmentKind = getAssignmentTargetKind(location); + const apparentType = getApparentType(assignmentKind !== AssignmentKind.None || isMethodAccessForCall(location) ? getWidenedType(leftType) : leftType); + prop = isPrivateIdentifier(right) ? lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(apparentType, lexicallyScopedSymbol) || undefined : getPropertyOfType(apparentType, right.escapedText); + } + if ( + !(prop && (isConstEnumOrConstEnumOnlyModule(prop) || prop.flags & SymbolFlags.EnumMember && location.parent.kind === SyntaxKind.EnumMember)) + ) { + markAliasReferenced(parentSymbol, location); + } + return; + } + + function markExportAssignmentAliasReferenced(location: ExportAssignment) { + if (isIdentifier(location.expression)) { + const id = location.expression; + const sym = getExportSymbolOfValueSymbolIfExported(resolveEntityName(id, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location)); + if (sym) { + markAliasReferenced(sym, id); + } + } + } + + function markJsxAliasReferenced(node: JsxOpeningLikeElement | JsxOpeningFragment) { + if (!getJsxNamespaceContainerForImplicitImport(node)) { + // The reactNamespace/jsxFactory's root symbol should be marked as 'used' so we don't incorrectly elide its import. + // And if there is no reactNamespace/jsxFactory's symbol in scope when targeting React emit, we should issue an error. + const jsxFactoryRefErr = diagnostics && compilerOptions.jsx === JsxEmit.React ? Diagnostics.Cannot_find_name_0 : undefined; + const jsxFactoryNamespace = getJsxNamespace(node); + const jsxFactoryLocation = isJsxOpeningLikeElement(node) ? node.tagName : node; + + // allow null as jsxFragmentFactory + let jsxFactorySym: Symbol | undefined; + if (!(isJsxOpeningFragment(node) && jsxFactoryNamespace === "null")) { + jsxFactorySym = resolveName(jsxFactoryLocation, jsxFactoryNamespace, SymbolFlags.Value, jsxFactoryRefErr, /*isUse*/ true); + } + + if (jsxFactorySym) { + // Mark local symbol as referenced here because it might not have been marked + // if jsx emit was not jsxFactory as there wont be error being emitted + jsxFactorySym.isReferenced = SymbolFlags.All; + + // If react/jsxFactory symbol is alias, mark it as refereced + if (canCollectSymbolAliasAccessabilityData && jsxFactorySym.flags & SymbolFlags.Alias && !getTypeOnlyAliasDeclaration(jsxFactorySym)) { + markAliasSymbolAsReferenced(jsxFactorySym); + } + } + + // For JsxFragment, mark jsx pragma as referenced via resolveName + if (isJsxOpeningFragment(node)) { + const file = getSourceFileOfNode(node); + const localJsxNamespace = getLocalJsxNamespace(file); + if (localJsxNamespace) { + resolveName(jsxFactoryLocation, localJsxNamespace, SymbolFlags.Value, jsxFactoryRefErr, /*isUse*/ true); + } + } + } + return; + } + + function markAsyncFunctionAliasReferenced(location: FunctionLikeDeclaration | MethodSignature) { + if (languageVersion < ScriptTarget.ES2015) { + if (getFunctionFlags(location) & FunctionFlags.Async) { + const returnTypeNode = getEffectiveReturnTypeNode(location); + markTypeNodeAsReferenced(returnTypeNode); + } + } + } + + function markImportEqualsAliasReferenced(location: ImportEqualsDeclaration) { + if (hasSyntacticModifier(location, ModifierFlags.Export)) { + markExportAsReferenced(location); + } + } + + function markExportSpecifierAliasReferenced(location: ExportSpecifier) { + if (!location.parent.parent.moduleSpecifier && !location.isTypeOnly && !location.parent.parent.isTypeOnly) { + const exportedName = location.propertyName || location.name; + if (exportedName.kind === SyntaxKind.StringLiteral) { + return; // Skip for invalid syntax like this: export { "x" } + } + const symbol = resolveName(exportedName, exportedName.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (symbol && (symbol === undefinedSymbol || symbol === globalThisSymbol || symbol.declarations && isGlobalSourceFile(getDeclarationContainer(symbol.declarations[0])))) { + // Do nothing, non-local symbol + } + else { + const target = symbol && (symbol.flags & SymbolFlags.Alias ? resolveAlias(symbol) : symbol); + if (!target || getSymbolFlags(target) & SymbolFlags.Value) { + markExportAsReferenced(location); // marks export as used + markIdentifierAliasReferenced(exportedName); // marks target of export as used + } + } + return; + } + } + + function markDecoratorAliasReferenced(node: HasDecorators) { + if (compilerOptions.emitDecoratorMetadata) { + const firstDecorator = find(node.modifiers, isDecorator); + if (!firstDecorator) { + return; + } + + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Metadata); + + // we only need to perform these checks if we are emitting serialized type metadata for the target of a decorator. + switch (node.kind) { + case SyntaxKind.ClassDeclaration: + const constructor = getFirstConstructorWithBody(node); + if (constructor) { + for (const parameter of constructor.parameters) { + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); + } + } + break; + + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + const otherKind = node.kind === SyntaxKind.GetAccessor ? SyntaxKind.SetAccessor : SyntaxKind.GetAccessor; + const otherAccessor = getDeclarationOfKind(getSymbolOfDeclaration(node), otherKind); + markDecoratorMedataDataTypeNodeAsReferenced(getAnnotatedAccessorTypeNode(node) || otherAccessor && getAnnotatedAccessorTypeNode(otherAccessor)); + break; + case SyntaxKind.MethodDeclaration: + for (const parameter of node.parameters) { + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); + } + + markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveReturnTypeNode(node)); + break; + + case SyntaxKind.PropertyDeclaration: + markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveTypeAnnotationNode(node)); + break; + + case SyntaxKind.Parameter: + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(node)); + const containingSignature = node.parent; + for (const parameter of containingSignature.parameters) { + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); + } + markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveReturnTypeNode(containingSignature)); + break; + } + } + } + + function markAliasReferenced(symbol: Symbol, location: Node) { + if (!canCollectSymbolAliasAccessabilityData) { + return; + } + if (isNonLocalAlias(symbol, /*excludes*/ SymbolFlags.Value) && !isInTypeQuery(location)) { + const target = resolveAlias(symbol); + if (getSymbolFlags(symbol, /*excludeTypeOnlyMeanings*/ true) & (SymbolFlags.Value | SymbolFlags.ExportValue)) { + // An alias resolving to a const enum cannot be elided if (1) 'isolatedModules' is enabled + // (because the const enum value will not be inlined), or if (2) the alias is an export + // of a const enum declaration that will be preserved. + if ( + getIsolatedModules(compilerOptions) || + shouldPreserveConstEnums(compilerOptions) && isExportOrExportExpression(location) || + !isConstEnumOrConstEnumOnlyModule(getExportSymbolOfValueSymbolIfExported(target)) + ) { + markAliasSymbolAsReferenced(symbol); + } + } + } + } + + // When an alias symbol is referenced, we need to mark the entity it references as referenced and in turn repeat that until + // we reach a non-alias or an exported entity (which is always considered referenced). We do this by checking the target of + // the alias as an expression (which recursively takes us back here if the target references another alias). + function markAliasSymbolAsReferenced(symbol: Symbol) { + Debug.assert(canCollectSymbolAliasAccessabilityData); + const links = getSymbolLinks(symbol); + if (!links.referenced) { + links.referenced = true; + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + // We defer checking of the reference of an `import =` until the import itself is referenced, + // This way a chain of imports can be elided if ultimately the final input is only used in a type + // position. + if (isInternalModuleImportEqualsDeclaration(node)) { + if (getSymbolFlags(resolveSymbol(symbol)) & SymbolFlags.Value) { + // import foo = + const left = getFirstIdentifier(node.moduleReference as EntityNameExpression); + markIdentifierAliasReferenced(left); + } + } + } + } + + function markExportAsReferenced(node: ImportEqualsDeclaration | ExportSpecifier) { + const symbol = getSymbolOfDeclaration(node); + const target = resolveAlias(symbol); + if (target) { + const markAlias = target === unknownSymbol || + ((getSymbolFlags(symbol, /*excludeTypeOnlyMeanings*/ true) & SymbolFlags.Value) && !isConstEnumOrConstEnumOnlyModule(target)); + + if (markAlias) { + markAliasSymbolAsReferenced(symbol); + } + } + } + + function markEntityNameOrEntityExpressionAsReference(typeName: EntityNameOrEntityNameExpression | undefined, forDecoratorMetadata: boolean) { + if (!typeName) return; + + const rootName = getFirstIdentifier(typeName); + const meaning = (typeName.kind === SyntaxKind.Identifier ? SymbolFlags.Type : SymbolFlags.Namespace) | SymbolFlags.Alias; + const rootSymbol = resolveName(rootName, rootName.escapedText, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (rootSymbol && rootSymbol.flags & SymbolFlags.Alias) { + if ( + canCollectSymbolAliasAccessabilityData + && symbolIsValue(rootSymbol) + && !isConstEnumOrConstEnumOnlyModule(resolveAlias(rootSymbol)) + && !getTypeOnlyAliasDeclaration(rootSymbol) + ) { + markAliasSymbolAsReferenced(rootSymbol); + } + else if ( + forDecoratorMetadata + && getIsolatedModules(compilerOptions) + && getEmitModuleKind(compilerOptions) >= ModuleKind.ES2015 + && !symbolIsValue(rootSymbol) + && !some(rootSymbol.declarations, isTypeOnlyImportOrExportDeclaration) + ) { + const diag = error(typeName, Diagnostics.A_type_referenced_in_a_decorated_signature_must_be_imported_with_import_type_or_a_namespace_import_when_isolatedModules_and_emitDecoratorMetadata_are_enabled); + const aliasDeclaration = find(rootSymbol.declarations || emptyArray, isAliasSymbolDeclaration); + if (aliasDeclaration) { + addRelatedInfo(diag, createDiagnosticForNode(aliasDeclaration, Diagnostics._0_was_imported_here, idText(rootName))); + } + } + } + } + + /** + * If a TypeNode can be resolved to a value symbol imported from an external module, it is + * marked as referenced to prevent import elision. + */ + function markTypeNodeAsReferenced(node: TypeNode | undefined) { + markEntityNameOrEntityExpressionAsReference(node && getEntityNameFromTypeNode(node), /*forDecoratorMetadata*/ false); + } + + /** + * This function marks the type used for metadata decorator as referenced if it is import + * from external module. + * This is different from markTypeNodeAsReferenced because it tries to simplify type nodes in + * union and intersection type + * @param node + */ + function markDecoratorMedataDataTypeNodeAsReferenced(node: TypeNode | undefined): void { + const entityName = getEntityNameForDecoratorMetadata(node); + if (entityName && isEntityName(entityName)) { + markEntityNameOrEntityExpressionAsReference(entityName, /*forDecoratorMetadata*/ true); + } + } + + function getNarrowedTypeOfSymbol(symbol: Symbol, location: Identifier, checkMode?: CheckMode) { + const type = getTypeOfSymbol(symbol, checkMode); + const declaration = symbol.valueDeclaration; + if (declaration) { + // If we have a non-rest binding element with no initializer declared as a const variable or a const-like + // parameter (a parameter for which there are no assignments in the function body), and if the parent type + // for the destructuring is a union type, one or more of the binding elements may represent discriminant + // properties, and we want the effects of conditional checks on such discriminants to affect the types of + // other binding elements from the same destructuring. Consider: + // + // type Action = + // | { kind: 'A', payload: number } + // | { kind: 'B', payload: string }; + // + // function f({ kind, payload }: Action) { + // if (kind === 'A') { + // payload.toFixed(); + // } + // if (kind === 'B') { + // payload.toUpperCase(); + // } + // } + // + // Above, we want the conditional checks on 'kind' to affect the type of 'payload'. To facilitate this, we use + // the binding pattern AST instance for '{ kind, payload }' as a pseudo-reference and narrow this reference + // as if it occurred in the specified location. We then recompute the narrowed binding element type by + // destructuring from the narrowed parent type. + if (isBindingElement(declaration) && !declaration.initializer && !declaration.dotDotDotToken && declaration.parent.elements.length >= 2) { + const parent = declaration.parent.parent; + const rootDeclaration = getRootDeclaration(parent); + if (rootDeclaration.kind === SyntaxKind.VariableDeclaration && getCombinedNodeFlagsCached(rootDeclaration) & NodeFlags.Constant || rootDeclaration.kind === SyntaxKind.Parameter) { + const links = getNodeLinks(parent); + if (!(links.flags & NodeCheckFlags.InCheckIdentifier)) { + links.flags |= NodeCheckFlags.InCheckIdentifier; + const parentType = getTypeForBindingElementParent(parent, CheckMode.Normal); + const parentTypeConstraint = parentType && mapType(parentType, getBaseConstraintOrType); + links.flags &= ~NodeCheckFlags.InCheckIdentifier; + if (parentTypeConstraint && parentTypeConstraint.flags & TypeFlags.Union && !(rootDeclaration.kind === SyntaxKind.Parameter && isSomeSymbolAssigned(rootDeclaration))) { + const pattern = declaration.parent; + const narrowedType = getFlowTypeOfReference(pattern, parentTypeConstraint, parentTypeConstraint, /*flowContainer*/ undefined, location.flowNode); + if (narrowedType.flags & TypeFlags.Never) { + return neverType; + } + // Destructurings are validated against the parent type elsewhere. Here we disable tuple bounds + // checks because the narrowed type may have lower arity than the full parent type. For example, + // for the declaration [x, y]: [1, 2] | [3], we may have narrowed the parent type to just [3]. + return getBindingElementTypeFromParentType(declaration, narrowedType, /*noTupleBoundsCheck*/ true); + } + } + } + } + // If we have a const-like parameter with no type annotation or initializer, and if the parameter is contextually + // typed by a signature with a single rest parameter of a union of tuple types, one or more of the parameters may + // represent discriminant tuple elements, and we want the effects of conditional checks on such discriminants to + // affect the types of other parameters in the same parameter list. Consider: + // + // type Action = [kind: 'A', payload: number] | [kind: 'B', payload: string]; + // + // const f: (...args: Action) => void = (kind, payload) => { + // if (kind === 'A') { + // payload.toFixed(); + // } + // if (kind === 'B') { + // payload.toUpperCase(); + // } + // } + // + // Above, we want the conditional checks on 'kind' to affect the type of 'payload'. To facilitate this, we use + // the arrow function AST node for '(kind, payload) => ...' as a pseudo-reference and narrow this reference as + // if it occurred in the specified location. We then recompute the narrowed parameter type by indexing into the + // narrowed tuple type. + if (isParameter(declaration) && !declaration.type && !declaration.initializer && !declaration.dotDotDotToken) { + const func = declaration.parent; + if (func.parameters.length >= 2 && isContextSensitiveFunctionOrObjectLiteralMethod(func)) { + const contextualSignature = getContextualSignature(func); + if (contextualSignature && contextualSignature.parameters.length === 1 && signatureHasRestParameter(contextualSignature)) { + const restType = getReducedApparentType(instantiateType(getTypeOfSymbol(contextualSignature.parameters[0]), getInferenceContext(func)?.nonFixingMapper)); + if (restType.flags & TypeFlags.Union && everyType(restType, isTupleType) && !some(func.parameters, isSomeSymbolAssigned)) { + const narrowedType = getFlowTypeOfReference(func, restType, restType, /*flowContainer*/ undefined, location.flowNode); + const index = func.parameters.indexOf(declaration) - (getThisParameter(func) ? 1 : 0); + return getIndexedAccessType(narrowedType, getNumberLiteralType(index)); + } + } + } + } + } + return type; + } + + /** + * This part of `checkIdentifier` is kept seperate from the rest, so `NodeCheckFlags` (and related diagnostics) can be lazily calculated + * without calculating the flow type of the identifier. + */ + function checkIdentifierCalculateNodeCheckFlags(node: Identifier, symbol: Symbol) { + if (isThisInTypeQuery(node)) return; + + // As noted in ECMAScript 6 language spec, arrow functions never have an arguments objects. + // Although in down-level emit of arrow function, we emit it using function expression which means that + // arguments objects will be bound to the inner object; emitting arrow function natively in ES6, arguments objects + // will be bound to non-arrow function that contain this arrow function. This results in inconsistent behavior. + // To avoid that we will give an error to users if they use arguments objects in arrow function so that they + // can explicitly bound arguments objects + if (symbol === argumentsSymbol) { + if (isInPropertyInitializerOrClassStaticBlock(node)) { + error(node, Diagnostics.arguments_cannot_be_referenced_in_property_initializers); + return; + } + + let container = getContainingFunction(node); + if (container) { + if (languageVersion < ScriptTarget.ES2015) { + if (container.kind === SyntaxKind.ArrowFunction) { + error(node, Diagnostics.The_arguments_object_cannot_be_referenced_in_an_arrow_function_in_ES5_Consider_using_a_standard_function_expression); + } + else if (hasSyntacticModifier(container, ModifierFlags.Async)) { + error(node, Diagnostics.The_arguments_object_cannot_be_referenced_in_an_async_function_or_method_in_ES5_Consider_using_a_standard_function_or_method); + } + } + + getNodeLinks(container).flags |= NodeCheckFlags.CaptureArguments; + while (container && isArrowFunction(container)) { + container = getContainingFunction(container); + if (container) { + getNodeLinks(container).flags |= NodeCheckFlags.CaptureArguments; + } + } + } + return; + } + + const localOrExportSymbol = getExportSymbolOfValueSymbolIfExported(symbol); + const targetSymbol = resolveAliasWithDeprecationCheck(localOrExportSymbol, node); + if (isDeprecatedSymbol(targetSymbol) && isUncalledFunctionReference(node, targetSymbol) && targetSymbol.declarations) { + addDeprecatedSuggestion(node, targetSymbol.declarations, node.escapedText as string); + } + + const declaration = localOrExportSymbol.valueDeclaration; + if (declaration && localOrExportSymbol.flags & SymbolFlags.Class) { + // When we downlevel classes we may emit some code outside of the class body. Due to the fact the + // class name is double-bound, we must ensure we mark references to the class name so that we can + // emit an alias to the class later. + if (isClassLike(declaration) && declaration.name !== node) { + let container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + while (container.kind !== SyntaxKind.SourceFile && container.parent !== declaration) { + container = getThisContainer(container, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + } + + if (container.kind !== SyntaxKind.SourceFile) { + getNodeLinks(declaration).flags |= NodeCheckFlags.ContainsConstructorReference; + getNodeLinks(container).flags |= NodeCheckFlags.ContainsConstructorReference; + getNodeLinks(node).flags |= NodeCheckFlags.ConstructorReference; + } + } + } + + checkNestedBlockScopedBinding(node, symbol); + } + + function checkIdentifier(node: Identifier, checkMode: CheckMode | undefined): Type { + if (isThisInTypeQuery(node)) { + return checkThisExpression(node); + } + + const symbol = getResolvedSymbol(node); + if (symbol === unknownSymbol) { + return errorType; + } + + checkIdentifierCalculateNodeCheckFlags(node, symbol); + + if (symbol === argumentsSymbol) { + if (isInPropertyInitializerOrClassStaticBlock(node)) { + return errorType; + } + return getTypeOfSymbol(symbol); + } + + if (shouldMarkIdentifierAliasReferenced(node)) { + markLinkedReferences(node, ReferenceHint.Identifier); + } + + const localOrExportSymbol = getExportSymbolOfValueSymbolIfExported(symbol); + let declaration = localOrExportSymbol.valueDeclaration; + + let type = getNarrowedTypeOfSymbol(localOrExportSymbol, node, checkMode); + const assignmentKind = getAssignmentTargetKind(node); + + if (assignmentKind) { + if ( + !(localOrExportSymbol.flags & SymbolFlags.Variable) && + !(isInJSFile(node) && localOrExportSymbol.flags & SymbolFlags.ValueModule) + ) { + const assignmentError = localOrExportSymbol.flags & SymbolFlags.Enum ? Diagnostics.Cannot_assign_to_0_because_it_is_an_enum + : localOrExportSymbol.flags & SymbolFlags.Class ? Diagnostics.Cannot_assign_to_0_because_it_is_a_class + : localOrExportSymbol.flags & SymbolFlags.Module ? Diagnostics.Cannot_assign_to_0_because_it_is_a_namespace + : localOrExportSymbol.flags & SymbolFlags.Function ? Diagnostics.Cannot_assign_to_0_because_it_is_a_function + : localOrExportSymbol.flags & SymbolFlags.Alias ? Diagnostics.Cannot_assign_to_0_because_it_is_an_import + : Diagnostics.Cannot_assign_to_0_because_it_is_not_a_variable; + + error(node, assignmentError, symbolToString(symbol)); + return errorType; + } + if (isReadonlySymbol(localOrExportSymbol)) { + if (localOrExportSymbol.flags & SymbolFlags.Variable) { + error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant, symbolToString(symbol)); + } + else { + error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(symbol)); + } + return errorType; + } + } + + const isAlias = localOrExportSymbol.flags & SymbolFlags.Alias; + + // We only narrow variables and parameters occurring in a non-assignment position. For all other + // entities we simply return the declared type. + if (localOrExportSymbol.flags & SymbolFlags.Variable) { + if (assignmentKind === AssignmentKind.Definite) { + return isInCompoundLikeAssignment(node) ? getBaseTypeOfLiteralType(type) : type; + } + } + else if (isAlias) { + declaration = getDeclarationOfAliasSymbol(symbol); + } + else { + return type; + } + + if (!declaration) { + return type; + } + + type = getNarrowableTypeForReference(type, node, checkMode); + + // The declaration container is the innermost function that encloses the declaration of the variable + // or parameter. The flow container is the innermost function starting with which we analyze the control + // flow graph to determine the control flow based type. + const isParameter = getRootDeclaration(declaration).kind === SyntaxKind.Parameter; + const declarationContainer = getControlFlowContainer(declaration); + let flowContainer = getControlFlowContainer(node); + const isOuterVariable = flowContainer !== declarationContainer; + const isSpreadDestructuringAssignmentTarget = node.parent && node.parent.parent && isSpreadAssignment(node.parent) && isDestructuringAssignmentTarget(node.parent.parent); + const isModuleExports = symbol.flags & SymbolFlags.ModuleExports; + const typeIsAutomatic = type === autoType || type === autoArrayType; + const isAutomaticTypeInNonNull = typeIsAutomatic && node.parent.kind === SyntaxKind.NonNullExpression; + // When the control flow originates in a function expression, arrow function, method, or accessor, and + // we are referencing a closed-over const variable or parameter or mutable local variable past its last + // assignment, we extend the origin of the control flow analysis to include the immediately enclosing + // control flow container. + while ( + flowContainer !== declarationContainer && ( + flowContainer.kind === SyntaxKind.FunctionExpression || + flowContainer.kind === SyntaxKind.ArrowFunction || + isObjectLiteralOrClassExpressionMethodOrAccessor(flowContainer) + ) && ( + isConstantVariable(localOrExportSymbol) && type !== autoArrayType || + isParameterOrMutableLocalVariable(localOrExportSymbol) && isPastLastAssignment(localOrExportSymbol, node) + ) + ) { + flowContainer = getControlFlowContainer(flowContainer); + } + // We only look for uninitialized variables in strict null checking mode, and only when we can analyze + // the entire control flow graph from the variable's declaration (i.e. when the flow container and + // declaration container are the same). + const assumeInitialized = isParameter || isAlias || isOuterVariable || isSpreadDestructuringAssignmentTarget || isModuleExports || isSameScopedBindingElement(node, declaration) || + type !== autoType && type !== autoArrayType && (!strictNullChecks || (type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void)) !== 0 || + isInTypeQuery(node) || isInAmbientOrTypeNode(node) || node.parent.kind === SyntaxKind.ExportSpecifier) || + node.parent.kind === SyntaxKind.NonNullExpression || + declaration.kind === SyntaxKind.VariableDeclaration && (declaration as VariableDeclaration).exclamationToken || + declaration.flags & NodeFlags.Ambient; + const initialType = isAutomaticTypeInNonNull ? undefinedType : + assumeInitialized ? (isParameter ? removeOptionalityFromDeclaredType(type, declaration as VariableLikeDeclaration) : type) : + typeIsAutomatic ? undefinedType : getOptionalType(type); + const flowType = isAutomaticTypeInNonNull ? getNonNullableType(getFlowTypeOfReference(node, type, initialType, flowContainer)) : + getFlowTypeOfReference(node, type, initialType, flowContainer); + // A variable is considered uninitialized when it is possible to analyze the entire control flow graph + // from declaration to use, and when the variable's declared type doesn't include undefined but the + // control flow based type does include undefined. + if (!isEvolvingArrayOperationTarget(node) && (type === autoType || type === autoArrayType)) { + if (flowType === autoType || flowType === autoArrayType) { + if (noImplicitAny) { + error(getNameOfDeclaration(declaration), Diagnostics.Variable_0_implicitly_has_type_1_in_some_locations_where_its_type_cannot_be_determined, symbolToString(symbol), typeToString(flowType)); + error(node, Diagnostics.Variable_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); + } + return convertAutoToAny(flowType); + } + } + else if (!assumeInitialized && !containsUndefinedType(type) && containsUndefinedType(flowType)) { + error(node, Diagnostics.Variable_0_is_used_before_being_assigned, symbolToString(symbol)); + // Return the declared type to reduce follow-on errors + return type; + } + return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType; + } + + function isSameScopedBindingElement(node: Identifier, declaration: Declaration) { + if (isBindingElement(declaration)) { + const bindingElement = findAncestor(node, isBindingElement); + return bindingElement && getRootDeclaration(bindingElement) === getRootDeclaration(declaration); + } + } + + function shouldMarkIdentifierAliasReferenced(node: Identifier): boolean { + const parent = node.parent; + if (parent) { + // A property access expression LHS? checkPropertyAccessExpression will handle that. + if (isPropertyAccessExpression(parent) && parent.expression === node) { + return false; + } + // Next two check for an identifier inside a type only export. + if (isExportSpecifier(parent) && parent.isTypeOnly) { + return false; + } + const greatGrandparent = parent.parent?.parent; + if (greatGrandparent && isExportDeclaration(greatGrandparent) && greatGrandparent.isTypeOnly) { + return false; + } + } + return true; + } + + function isInsideFunctionOrInstancePropertyInitializer(node: Node, threshold: Node): boolean { + return !!findAncestor(node, n => + n === threshold ? "quit" : isFunctionLike(n) || ( + n.parent && isPropertyDeclaration(n.parent) && !hasStaticModifier(n.parent) && n.parent.initializer === n + )); + } + + function getPartOfForStatementContainingNode(node: Node, container: ForStatement) { + return findAncestor(node, n => n === container ? "quit" : n === container.initializer || n === container.condition || n === container.incrementor || n === container.statement); + } + + function getEnclosingIterationStatement(node: Node): Node | undefined { + return findAncestor(node, n => (!n || nodeStartsNewLexicalEnvironment(n)) ? "quit" : isIterationStatement(n, /*lookInLabeledStatements*/ false)); + } + + function checkNestedBlockScopedBinding(node: Identifier, symbol: Symbol): void { + if ( + languageVersion >= ScriptTarget.ES2015 || + (symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.Class)) === 0 || + !symbol.valueDeclaration || + isSourceFile(symbol.valueDeclaration) || + symbol.valueDeclaration.parent.kind === SyntaxKind.CatchClause + ) { + return; + } + + // 1. walk from the use site up to the declaration and check + // if there is anything function like between declaration and use-site (is binding/class is captured in function). + // 2. walk from the declaration up to the boundary of lexical environment and check + // if there is an iteration statement in between declaration and boundary (is binding/class declared inside iteration statement) + + const container = getEnclosingBlockScopeContainer(symbol.valueDeclaration); + const isCaptured = isInsideFunctionOrInstancePropertyInitializer(node, container); + + const enclosingIterationStatement = getEnclosingIterationStatement(container); + if (enclosingIterationStatement) { + if (isCaptured) { + // mark iteration statement as containing block-scoped binding captured in some function + let capturesBlockScopeBindingInLoopBody = true; + if (isForStatement(container)) { + const varDeclList = getAncestor(symbol.valueDeclaration, SyntaxKind.VariableDeclarationList); + if (varDeclList && varDeclList.parent === container) { + const part = getPartOfForStatementContainingNode(node.parent, container); + if (part) { + const links = getNodeLinks(part); + links.flags |= NodeCheckFlags.ContainsCapturedBlockScopeBinding; + + const capturedBindings = links.capturedBlockScopeBindings || (links.capturedBlockScopeBindings = []); + pushIfUnique(capturedBindings, symbol); + + if (part === container.initializer) { + capturesBlockScopeBindingInLoopBody = false; // Initializer is outside of loop body + } + } + } + } + if (capturesBlockScopeBindingInLoopBody) { + getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; + } + } + + // mark variables that are declared in loop initializer and reassigned inside the body of ForStatement. + // if body of ForStatement will be converted to function then we'll need a extra machinery to propagate reassigned values back. + if (isForStatement(container)) { + const varDeclList = getAncestor(symbol.valueDeclaration, SyntaxKind.VariableDeclarationList); + if (varDeclList && varDeclList.parent === container && isAssignedInBodyOfForStatement(node, container)) { + getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.NeedsLoopOutParameter; + } + } + + // set 'declared inside loop' bit on the block-scoped binding + getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + } + + if (isCaptured) { + getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.CapturedBlockScopedBinding; + } + } + + function isBindingCapturedByNode(node: Node, decl: VariableDeclaration | BindingElement) { + const links = getNodeLinks(node); + return !!links && contains(links.capturedBlockScopeBindings, getSymbolOfDeclaration(decl)); + } + + function isAssignedInBodyOfForStatement(node: Identifier, container: ForStatement): boolean { + // skip parenthesized nodes + let current: Node = node; + while (current.parent.kind === SyntaxKind.ParenthesizedExpression) { + current = current.parent; + } + + // check if node is used as LHS in some assignment expression + let isAssigned = false; + if (isAssignmentTarget(current)) { + isAssigned = true; + } + else if ((current.parent.kind === SyntaxKind.PrefixUnaryExpression || current.parent.kind === SyntaxKind.PostfixUnaryExpression)) { + const expr = current.parent as PrefixUnaryExpression | PostfixUnaryExpression; + isAssigned = expr.operator === SyntaxKind.PlusPlusToken || expr.operator === SyntaxKind.MinusMinusToken; + } + + if (!isAssigned) { + return false; + } + + // at this point we know that node is the target of assignment + // now check that modification happens inside the statement part of the ForStatement + return !!findAncestor(current, n => n === container ? "quit" : n === container.statement); + } + + function captureLexicalThis(node: Node, container: Node): void { + getNodeLinks(node).flags |= NodeCheckFlags.LexicalThis; + if (container.kind === SyntaxKind.PropertyDeclaration || container.kind === SyntaxKind.Constructor) { + const classNode = container.parent; + getNodeLinks(classNode).flags |= NodeCheckFlags.CaptureThis; + } + else { + getNodeLinks(container).flags |= NodeCheckFlags.CaptureThis; + } + } + + function findFirstSuperCall(node: Node): SuperCall | undefined { + return isSuperCall(node) ? node : + isFunctionLike(node) ? undefined : + forEachChild(node, findFirstSuperCall); + } + + /** + * Check if the given class-declaration extends null then return true. + * Otherwise, return false + * @param classDecl a class declaration to check if it extends null + */ + function classDeclarationExtendsNull(classDecl: ClassLikeDeclaration): boolean { + const classSymbol = getSymbolOfDeclaration(classDecl); + const classInstanceType = getDeclaredTypeOfSymbol(classSymbol) as InterfaceType; + const baseConstructorType = getBaseConstructorTypeOfClass(classInstanceType); + + return baseConstructorType === nullWideningType; + } + + function checkThisBeforeSuper(node: Node, container: Node, diagnosticMessage: DiagnosticMessage) { + const containingClassDecl = container.parent as ClassDeclaration; + const baseTypeNode = getClassExtendsHeritageElement(containingClassDecl); + + // If a containing class does not have extends clause or the class extends null + // skip checking whether super statement is called before "this" accessing. + if (baseTypeNode && !classDeclarationExtendsNull(containingClassDecl)) { + if (canHaveFlowNode(node) && node.flowNode && !isPostSuperFlowNode(node.flowNode, /*noCacheCheck*/ false)) { + error(node, diagnosticMessage); + } + } + } + + function checkThisInStaticClassFieldInitializerInDecoratedClass(thisExpression: Node, container: Node) { + if ( + isPropertyDeclaration(container) && hasStaticModifier(container) && legacyDecorators && + container.initializer && textRangeContainsPositionInclusive(container.initializer, thisExpression.pos) && hasDecorators(container.parent) + ) { + error(thisExpression, Diagnostics.Cannot_use_this_in_a_static_property_initializer_of_a_decorated_class); + } + } + + function checkThisExpression(node: Node): Type { + const isNodeInTypeQuery = isInTypeQuery(node); + // Stop at the first arrow function so that we can + // tell whether 'this' needs to be captured. + let container = getThisContainer(node, /*includeArrowFunctions*/ true, /*includeClassComputedPropertyName*/ true); + let capturedByArrowFunction = false; + let thisInComputedPropertyName = false; + + if (container.kind === SyntaxKind.Constructor) { + checkThisBeforeSuper(node, container, Diagnostics.super_must_be_called_before_accessing_this_in_the_constructor_of_a_derived_class); + } + + while (true) { + // Now skip arrow functions to get the "real" owner of 'this'. + if (container.kind === SyntaxKind.ArrowFunction) { + container = getThisContainer(container, /*includeArrowFunctions*/ false, !thisInComputedPropertyName); + capturedByArrowFunction = true; + } + + if (container.kind === SyntaxKind.ComputedPropertyName) { + container = getThisContainer(container, !capturedByArrowFunction, /*includeClassComputedPropertyName*/ false); + thisInComputedPropertyName = true; + continue; + } + + break; + } + + checkThisInStaticClassFieldInitializerInDecoratedClass(node, container); + if (thisInComputedPropertyName) { + error(node, Diagnostics.this_cannot_be_referenced_in_a_computed_property_name); + } + else { + switch (container.kind) { + case SyntaxKind.ModuleDeclaration: + error(node, Diagnostics.this_cannot_be_referenced_in_a_module_or_namespace_body); + // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks + break; + case SyntaxKind.EnumDeclaration: + error(node, Diagnostics.this_cannot_be_referenced_in_current_location); + // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks + break; + } + } + + // When targeting es6, mark that we'll need to capture `this` in its lexically bound scope. + if (!isNodeInTypeQuery && capturedByArrowFunction && languageVersion < ScriptTarget.ES2015) { + captureLexicalThis(node, container); + } + + const type = tryGetThisTypeAt(node, /*includeGlobalThis*/ true, container); + if (noImplicitThis) { + const globalThisType = getTypeOfSymbol(globalThisSymbol); + if (type === globalThisType && capturedByArrowFunction) { + error(node, Diagnostics.The_containing_arrow_function_captures_the_global_value_of_this); + } + else if (!type) { + // With noImplicitThis, functions may not reference 'this' if it has type 'any' + const diag = error(node, Diagnostics.this_implicitly_has_type_any_because_it_does_not_have_a_type_annotation); + if (!isSourceFile(container)) { + const outsideThis = tryGetThisTypeAt(container); + if (outsideThis && outsideThis !== globalThisType) { + addRelatedInfo(diag, createDiagnosticForNode(container, Diagnostics.An_outer_value_of_this_is_shadowed_by_this_container)); + } + } + } + } + return type || anyType; + } + + function tryGetThisTypeAt(node: Node, includeGlobalThis = true, container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)): Type | undefined { + const isInJS = isInJSFile(node); + if ( + isFunctionLike(container) && + (!isInParameterInitializerBeforeContainingFunction(node) || getThisParameter(container)) + ) { + let thisType = getThisTypeOfDeclaration(container) || isInJS && getTypeForThisExpressionFromJSDoc(container); + // Note: a parameter initializer should refer to class-this unless function-this is explicitly annotated. + // If this is a function in a JS file, it might be a class method. + if (!thisType) { + const className = getClassNameFromPrototypeMethod(container); + if (isInJS && className) { + const classSymbol = checkExpression(className).symbol; + if (classSymbol && classSymbol.members && (classSymbol.flags & SymbolFlags.Function)) { + thisType = (getDeclaredTypeOfSymbol(classSymbol) as InterfaceType).thisType; + } + } + else if (isJSConstructor(container)) { + thisType = (getDeclaredTypeOfSymbol(getMergedSymbol(container.symbol)) as InterfaceType).thisType; + } + thisType ||= getContextualThisParameterType(container); + } + + if (thisType) { + return getFlowTypeOfReference(node, thisType); + } + } + + if (isClassLike(container.parent)) { + const symbol = getSymbolOfDeclaration(container.parent); + const type = isStatic(container) ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!; + return getFlowTypeOfReference(node, type); + } + + if (isSourceFile(container)) { + // look up in the source file's locals or exports + if (container.commonJsModuleIndicator) { + const fileSymbol = getSymbolOfDeclaration(container); + return fileSymbol && getTypeOfSymbol(fileSymbol); + } + else if (container.externalModuleIndicator) { + // TODO: Maybe issue a better error than 'object is possibly undefined' + return undefinedType; + } + else if (includeGlobalThis) { + return getTypeOfSymbol(globalThisSymbol); + } + } + } + + function getExplicitThisType(node: Expression) { + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (isFunctionLike(container)) { + const signature = getSignatureFromDeclaration(container); + if (signature.thisParameter) { + return getExplicitTypeOfSymbol(signature.thisParameter); + } + } + if (isClassLike(container.parent)) { + const symbol = getSymbolOfDeclaration(container.parent); + return isStatic(container) ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!; + } + } + + function getClassNameFromPrototypeMethod(container: Node) { + // Check if it's the RHS of a x.prototype.y = function [name]() { .... } + if ( + container.kind === SyntaxKind.FunctionExpression && + isBinaryExpression(container.parent) && + getAssignmentDeclarationKind(container.parent) === AssignmentDeclarationKind.PrototypeProperty + ) { + // Get the 'x' of 'x.prototype.y = container' + return ((container.parent // x.prototype.y = container + .left as PropertyAccessExpression) // x.prototype.y + .expression as PropertyAccessExpression) // x.prototype + .expression; // x + } + // x.prototype = { method() { } } + else if ( + container.kind === SyntaxKind.MethodDeclaration && + container.parent.kind === SyntaxKind.ObjectLiteralExpression && + isBinaryExpression(container.parent.parent) && + getAssignmentDeclarationKind(container.parent.parent) === AssignmentDeclarationKind.Prototype + ) { + return (container.parent.parent.left as PropertyAccessExpression).expression; + } + // x.prototype = { method: function() { } } + else if ( + container.kind === SyntaxKind.FunctionExpression && + container.parent.kind === SyntaxKind.PropertyAssignment && + container.parent.parent.kind === SyntaxKind.ObjectLiteralExpression && + isBinaryExpression(container.parent.parent.parent) && + getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.Prototype + ) { + return (container.parent.parent.parent.left as PropertyAccessExpression).expression; + } + // Object.defineProperty(x, "method", { value: function() { } }); + // Object.defineProperty(x, "method", { set: (x: () => void) => void }); + // Object.defineProperty(x, "method", { get: () => function() { }) }); + else if ( + container.kind === SyntaxKind.FunctionExpression && + isPropertyAssignment(container.parent) && + isIdentifier(container.parent.name) && + (container.parent.name.escapedText === "value" || container.parent.name.escapedText === "get" || container.parent.name.escapedText === "set") && + isObjectLiteralExpression(container.parent.parent) && + isCallExpression(container.parent.parent.parent) && + container.parent.parent.parent.arguments[2] === container.parent.parent && + getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty + ) { + return (container.parent.parent.parent.arguments[0] as PropertyAccessExpression).expression; + } + // Object.defineProperty(x, "method", { value() { } }); + // Object.defineProperty(x, "method", { set(x: () => void) {} }); + // Object.defineProperty(x, "method", { get() { return () => {} } }); + else if ( + isMethodDeclaration(container) && + isIdentifier(container.name) && + (container.name.escapedText === "value" || container.name.escapedText === "get" || container.name.escapedText === "set") && + isObjectLiteralExpression(container.parent) && + isCallExpression(container.parent.parent) && + container.parent.parent.arguments[2] === container.parent && + getAssignmentDeclarationKind(container.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty + ) { + return (container.parent.parent.arguments[0] as PropertyAccessExpression).expression; + } + } + + function getTypeForThisExpressionFromJSDoc(node: SignatureDeclaration) { + const thisTag = getJSDocThisTag(node); + if (thisTag && thisTag.typeExpression) { + return getTypeFromTypeNode(thisTag.typeExpression); + } + const signature = getSignatureOfTypeTag(node); + if (signature) { + return getThisTypeOfSignature(signature); + } + } + + function isInConstructorArgumentInitializer(node: Node, constructorDecl: Node): boolean { + return !!findAncestor(node, n => isFunctionLikeDeclaration(n) ? "quit" : n.kind === SyntaxKind.Parameter && n.parent === constructorDecl); + } + + function checkSuperExpression(node: Node): Type { + const isCallExpression = node.parent.kind === SyntaxKind.CallExpression && (node.parent as CallExpression).expression === node; + + const immediateContainer = getSuperContainer(node, /*stopOnFunctions*/ true); + let container = immediateContainer; + let needToCaptureLexicalThis = false; + let inAsyncFunction = false; + + // adjust the container reference in case if super is used inside arrow functions with arbitrarily deep nesting + if (!isCallExpression) { + while (container && container.kind === SyntaxKind.ArrowFunction) { + if (hasSyntacticModifier(container, ModifierFlags.Async)) inAsyncFunction = true; + container = getSuperContainer(container, /*stopOnFunctions*/ true); + needToCaptureLexicalThis = languageVersion < ScriptTarget.ES2015; + } + if (container && hasSyntacticModifier(container, ModifierFlags.Async)) inAsyncFunction = true; + } + + let nodeCheckFlag: NodeCheckFlags = 0; + + if (!container || !isLegalUsageOfSuperExpression(container)) { + // issue more specific error if super is used in computed property name + // class A { foo() { return "1" }} + // class B { + // [super.foo()]() {} + // } + const current = findAncestor(node, n => n === container ? "quit" : n.kind === SyntaxKind.ComputedPropertyName); + if (current && current.kind === SyntaxKind.ComputedPropertyName) { + error(node, Diagnostics.super_cannot_be_referenced_in_a_computed_property_name); + } + else if (isCallExpression) { + error(node, Diagnostics.Super_calls_are_not_permitted_outside_constructors_or_in_nested_functions_inside_constructors); + } + else if (!container || !container.parent || !(isClassLike(container.parent) || container.parent.kind === SyntaxKind.ObjectLiteralExpression)) { + error(node, Diagnostics.super_can_only_be_referenced_in_members_of_derived_classes_or_object_literal_expressions); + } + else { + error(node, Diagnostics.super_property_access_is_permitted_only_in_a_constructor_member_function_or_member_accessor_of_a_derived_class); + } + return errorType; + } + + if (!isCallExpression && immediateContainer!.kind === SyntaxKind.Constructor) { + checkThisBeforeSuper(node, container, Diagnostics.super_must_be_called_before_accessing_a_property_of_super_in_the_constructor_of_a_derived_class); + } + + if (isStatic(container) || isCallExpression) { + nodeCheckFlag = NodeCheckFlags.SuperStatic; + if ( + !isCallExpression && + languageVersion >= ScriptTarget.ES2015 && languageVersion <= ScriptTarget.ES2021 && + (isPropertyDeclaration(container) || isClassStaticBlockDeclaration(container)) + ) { + // for `super.x` or `super[x]` in a static initializer, mark all enclosing + // block scope containers so that we can report potential collisions with + // `Reflect`. + forEachEnclosingBlockScopeContainer(node.parent, current => { + if (!isSourceFile(current) || isExternalOrCommonJsModule(current)) { + getNodeLinks(current).flags |= NodeCheckFlags.ContainsSuperPropertyInStaticInitializer; + } + }); + } + } + else { + nodeCheckFlag = NodeCheckFlags.SuperInstance; + } + + getNodeLinks(node).flags |= nodeCheckFlag; + + // Due to how we emit async functions, we need to specialize the emit for an async method that contains a `super` reference. + // This is due to the fact that we emit the body of an async function inside of a generator function. As generator + // functions cannot reference `super`, we emit a helper inside of the method body, but outside of the generator. This helper + // uses an arrow function, which is permitted to reference `super`. + // + // There are two primary ways we can access `super` from within an async method. The first is getting the value of a property + // or indexed access on super, either as part of a right-hand-side expression or call expression. The second is when setting the value + // of a property or indexed access, either as part of an assignment expression or destructuring assignment. + // + // The simplest case is reading a value, in which case we will emit something like the following: + // + // // ts + // ... + // async asyncMethod() { + // let x = await super.asyncMethod(); + // return x; + // } + // ... + // + // // js + // ... + // asyncMethod() { + // const _super = Object.create(null, { + // asyncMethod: { get: () => super.asyncMethod }, + // }); + // return __awaiter(this, arguments, Promise, function *() { + // let x = yield _super.asyncMethod.call(this); + // return x; + // }); + // } + // ... + // + // The more complex case is when we wish to assign a value, especially as part of a destructuring assignment. As both cases + // are legal in ES6, but also likely less frequent, we only emit setters if there is an assignment: + // + // // ts + // ... + // async asyncMethod(ar: Promise) { + // [super.a, super.b] = await ar; + // } + // ... + // + // // js + // ... + // asyncMethod(ar) { + // const _super = Object.create(null, { + // a: { get: () => super.a, set: (v) => super.a = v }, + // b: { get: () => super.b, set: (v) => super.b = v } + // }; + // return __awaiter(this, arguments, Promise, function *() { + // [_super.a, _super.b] = yield ar; + // }); + // } + // ... + // + // Creating an object that has getter and setters instead of just an accessor function is required for destructuring assignments + // as a call expression cannot be used as the target of a destructuring assignment while a property access can. + // + // For element access expressions (`super[x]`), we emit a generic helper that forwards the element access in both situations. + if (container.kind === SyntaxKind.MethodDeclaration && inAsyncFunction) { + if (isSuperProperty(node.parent) && isAssignmentTarget(node.parent)) { + getNodeLinks(container).flags |= NodeCheckFlags.MethodWithSuperPropertyAssignmentInAsync; + } + else { + getNodeLinks(container).flags |= NodeCheckFlags.MethodWithSuperPropertyAccessInAsync; + } + } + + if (needToCaptureLexicalThis) { + // call expressions are allowed only in constructors so they should always capture correct 'this' + // super property access expressions can also appear in arrow functions - + // in this case they should also use correct lexical this + captureLexicalThis(node.parent, container); + } + + if (container.parent.kind === SyntaxKind.ObjectLiteralExpression) { + if (languageVersion < ScriptTarget.ES2015) { + error(node, Diagnostics.super_is_only_allowed_in_members_of_object_literal_expressions_when_option_target_is_ES2015_or_higher); + return errorType; + } + else { + // for object literal assume that type of 'super' is 'any' + return anyType; + } + } + + // at this point the only legal case for parent is ClassLikeDeclaration + const classLikeDeclaration = container.parent as ClassLikeDeclaration; + if (!getClassExtendsHeritageElement(classLikeDeclaration)) { + error(node, Diagnostics.super_can_only_be_referenced_in_a_derived_class); + return errorType; + } + + if (classDeclarationExtendsNull(classLikeDeclaration)) { + return isCallExpression ? errorType : nullWideningType; + } + + const classType = getDeclaredTypeOfSymbol(getSymbolOfDeclaration(classLikeDeclaration)) as InterfaceType; + const baseClassType = classType && getBaseTypes(classType)[0]; + if (!baseClassType) { + return errorType; + } + + if (container.kind === SyntaxKind.Constructor && isInConstructorArgumentInitializer(node, container)) { + // issue custom error message for super property access in constructor arguments (to be aligned with old compiler) + error(node, Diagnostics.super_cannot_be_referenced_in_constructor_arguments); + return errorType; + } + + return nodeCheckFlag === NodeCheckFlags.SuperStatic + ? getBaseConstructorTypeOfClass(classType) + : getTypeWithThisArgument(baseClassType, classType.thisType); + + function isLegalUsageOfSuperExpression(container: Node): boolean { + if (isCallExpression) { + // TS 1.0 SPEC (April 2014): 4.8.1 + // Super calls are only permitted in constructors of derived classes + return container.kind === SyntaxKind.Constructor; + } + else { + // TS 1.0 SPEC (April 2014) + // 'super' property access is allowed + // - In a constructor, instance member function, instance member accessor, or instance member variable initializer where this references a derived class instance + // - In a static member function or static member accessor + + // topmost container must be something that is directly nested in the class declaration\object literal expression + if (isClassLike(container.parent) || container.parent.kind === SyntaxKind.ObjectLiteralExpression) { + if (isStatic(container)) { + return container.kind === SyntaxKind.MethodDeclaration || + container.kind === SyntaxKind.MethodSignature || + container.kind === SyntaxKind.GetAccessor || + container.kind === SyntaxKind.SetAccessor || + container.kind === SyntaxKind.PropertyDeclaration || + container.kind === SyntaxKind.ClassStaticBlockDeclaration; + } + else { + return container.kind === SyntaxKind.MethodDeclaration || + container.kind === SyntaxKind.MethodSignature || + container.kind === SyntaxKind.GetAccessor || + container.kind === SyntaxKind.SetAccessor || + container.kind === SyntaxKind.PropertyDeclaration || + container.kind === SyntaxKind.PropertySignature || + container.kind === SyntaxKind.Constructor; + } + } + } + + return false; + } + } + + function getContainingObjectLiteral(func: SignatureDeclaration): ObjectLiteralExpression | undefined { + return (func.kind === SyntaxKind.MethodDeclaration || + func.kind === SyntaxKind.GetAccessor || + func.kind === SyntaxKind.SetAccessor) && func.parent.kind === SyntaxKind.ObjectLiteralExpression ? func.parent : + func.kind === SyntaxKind.FunctionExpression && func.parent.kind === SyntaxKind.PropertyAssignment ? func.parent.parent as ObjectLiteralExpression : + undefined; + } + + function getThisTypeArgument(type: Type): Type | undefined { + return getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).target === globalThisType ? getTypeArguments(type as TypeReference)[0] : undefined; + } + + function getThisTypeFromContextualType(type: Type): Type | undefined { + return mapType(type, t => { + return t.flags & TypeFlags.Intersection ? forEach((t as IntersectionType).types, getThisTypeArgument) : getThisTypeArgument(t); + }); + } + + function getThisTypeOfObjectLiteralFromContextualType(containingLiteral: ObjectLiteralExpression, contextualType: Type | undefined) { + let literal = containingLiteral; + let type = contextualType; + while (type) { + const thisType = getThisTypeFromContextualType(type); + if (thisType) { + return thisType; + } + if (literal.parent.kind !== SyntaxKind.PropertyAssignment) { + break; + } + literal = literal.parent.parent as ObjectLiteralExpression; + type = getApparentTypeOfContextualType(literal, /*contextFlags*/ undefined); + } + } + + function getContextualThisParameterType(func: SignatureDeclaration): Type | undefined { + if (func.kind === SyntaxKind.ArrowFunction) { + return undefined; + } + if (isContextSensitiveFunctionOrObjectLiteralMethod(func)) { + const contextualSignature = getContextualSignature(func); + if (contextualSignature) { + const thisParameter = contextualSignature.thisParameter; + if (thisParameter) { + return getTypeOfSymbol(thisParameter); + } + } + } + const inJs = isInJSFile(func); + if (noImplicitThis || inJs) { + const containingLiteral = getContainingObjectLiteral(func); + if (containingLiteral) { + // We have an object literal method. Check if the containing object literal has a contextual type + // that includes a ThisType. If so, T is the contextual type for 'this'. We continue looking in + // any directly enclosing object literals. + const contextualType = getApparentTypeOfContextualType(containingLiteral, /*contextFlags*/ undefined); + const thisType = getThisTypeOfObjectLiteralFromContextualType(containingLiteral, contextualType); + if (thisType) { + return instantiateType(thisType, getMapperFromContext(getInferenceContext(containingLiteral))); + } + // There was no contextual ThisType for the containing object literal, so the contextual type + // for 'this' is the non-null form of the contextual type for the containing object literal or + // the type of the object literal itself. + return getWidenedType(contextualType ? getNonNullableType(contextualType) : checkExpressionCached(containingLiteral)); + } + // In an assignment of the form 'obj.xxx = function(...)' or 'obj[xxx] = function(...)', the + // contextual type for 'this' is 'obj'. + const parent = walkUpParenthesizedExpressions(func.parent); + if (isAssignmentExpression(parent)) { + const target = parent.left; + if (isAccessExpression(target)) { + const { expression } = target; + // Don't contextually type `this` as `exports` in `exports.Point = function(x, y) { this.x = x; this.y = y; }` + if (inJs && isIdentifier(expression)) { + const sourceFile = getSourceFileOfNode(parent); + if (sourceFile.commonJsModuleIndicator && getResolvedSymbol(expression) === sourceFile.symbol) { + return undefined; + } + } + + return getWidenedType(checkExpressionCached(expression)); + } + } + } + return undefined; + } + + // Return contextual type of parameter or undefined if no contextual type is available + function getContextuallyTypedParameterType(parameter: ParameterDeclaration): Type | undefined { + const func = parameter.parent; + if (!isContextSensitiveFunctionOrObjectLiteralMethod(func)) { + return undefined; + } + const iife = getImmediatelyInvokedFunctionExpression(func); + if (iife && iife.arguments) { + const args = getEffectiveCallArguments(iife); + const indexOfParameter = func.parameters.indexOf(parameter); + if (parameter.dotDotDotToken) { + return getSpreadArgumentType(args, indexOfParameter, args.length, anyType, /*context*/ undefined, CheckMode.Normal); + } + const links = getNodeLinks(iife); + const cached = links.resolvedSignature; + links.resolvedSignature = anySignature; + const type = indexOfParameter < args.length ? + getWidenedLiteralType(checkExpression(args[indexOfParameter])) : + parameter.initializer ? undefined : undefinedWideningType; + links.resolvedSignature = cached; + return type; + } + const contextualSignature = getContextualSignature(func); + if (contextualSignature) { + const index = func.parameters.indexOf(parameter) - (getThisParameter(func) ? 1 : 0); + return parameter.dotDotDotToken && lastOrUndefined(func.parameters) === parameter ? + getRestTypeAtPosition(contextualSignature, index) : + tryGetTypeAtPosition(contextualSignature, index); + } + } + + function getContextualTypeForVariableLikeDeclaration(declaration: VariableLikeDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + const typeNode = getEffectiveTypeAnnotationNode(declaration) || (isInJSFile(declaration) ? tryGetJSDocSatisfiesTypeNode(declaration) : undefined); + if (typeNode) { + return getTypeFromTypeNode(typeNode); + } + switch (declaration.kind) { + case SyntaxKind.Parameter: + return getContextuallyTypedParameterType(declaration); + case SyntaxKind.BindingElement: + return getContextualTypeForBindingElement(declaration, contextFlags); + case SyntaxKind.PropertyDeclaration: + if (isStatic(declaration)) { + return getContextualTypeForStaticPropertyDeclaration(declaration, contextFlags); + } + // By default, do nothing and return undefined - only the above cases have context implied by a parent + } + } + + function getContextualTypeForBindingElement(declaration: BindingElement, contextFlags: ContextFlags | undefined): Type | undefined { + const parent = declaration.parent.parent; + const name = declaration.propertyName || declaration.name; + const parentType = getContextualTypeForVariableLikeDeclaration(parent, contextFlags) || + parent.kind !== SyntaxKind.BindingElement && parent.initializer && checkDeclarationInitializer(parent, declaration.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal); + if (!parentType || isBindingPattern(name) || isComputedNonLiteralName(name)) return undefined; + if (parent.name.kind === SyntaxKind.ArrayBindingPattern) { + const index = indexOfNode(declaration.parent.elements, declaration); + if (index < 0) return undefined; + return getContextualTypeForElementExpression(parentType, index); + } + const nameType = getLiteralTypeFromPropertyName(name); + if (isTypeUsableAsPropertyName(nameType)) { + const text = getPropertyNameFromType(nameType); + return getTypeOfPropertyOfType(parentType, text); + } + } + + function getContextualTypeForStaticPropertyDeclaration(declaration: PropertyDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + const parentType = isExpression(declaration.parent) && getContextualType(declaration.parent, contextFlags); + if (!parentType) return undefined; + return getTypeOfPropertyOfContextualType(parentType, getSymbolOfDeclaration(declaration).escapedName); + } + + // In a variable, parameter or property declaration with a type annotation, + // the contextual type of an initializer expression is the type of the variable, parameter or property. + // Otherwise, in a parameter declaration of a contextually typed function expression, + // the contextual type of an initializer expression is the contextual type of the parameter. + // Otherwise, in a variable or parameter declaration with a binding pattern name, + // the contextual type of an initializer expression is the type implied by the binding pattern. + // Otherwise, in a binding pattern inside a variable or parameter declaration, + // the contextual type of an initializer expression is the type annotation of the containing declaration, if present. + function getContextualTypeForInitializerExpression(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const declaration = node.parent as VariableLikeDeclaration; + if (hasInitializer(declaration) && node === declaration.initializer) { + const result = getContextualTypeForVariableLikeDeclaration(declaration, contextFlags); + if (result) { + return result; + } + if (!(contextFlags! & ContextFlags.SkipBindingPatterns) && isBindingPattern(declaration.name) && declaration.name.elements.length > 0) { + return getTypeFromBindingPattern(declaration.name, /*includePatternInType*/ true, /*reportErrors*/ false); + } + } + return undefined; + } + + function getContextualTypeForReturnExpression(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const func = getContainingFunction(node); + if (func) { + let contextualReturnType = getContextualReturnType(func, contextFlags); + if (contextualReturnType) { + const functionFlags = getFunctionFlags(func); + if (functionFlags & FunctionFlags.Generator) { // Generator or AsyncGenerator function + const isAsyncGenerator = (functionFlags & FunctionFlags.Async) !== 0; + if (contextualReturnType.flags & TypeFlags.Union) { + contextualReturnType = filterType(contextualReturnType, type => !!getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, type, isAsyncGenerator)); + } + const iterationReturnType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, contextualReturnType, (functionFlags & FunctionFlags.Async) !== 0); + if (!iterationReturnType) { + return undefined; + } + contextualReturnType = iterationReturnType; + // falls through to unwrap Promise for AsyncGenerators + } + + if (functionFlags & FunctionFlags.Async) { // Async function or AsyncGenerator function + // Get the awaited type without the `Awaited` alias + const contextualAwaitedType = mapType(contextualReturnType, getAwaitedTypeNoAlias); + return contextualAwaitedType && getUnionType([contextualAwaitedType, createPromiseLikeType(contextualAwaitedType)]); + } + + return contextualReturnType; // Regular function or Generator function + } + } + return undefined; + } + + function getContextualTypeForAwaitOperand(node: AwaitExpression, contextFlags: ContextFlags | undefined): Type | undefined { + const contextualType = getContextualType(node, contextFlags); + if (contextualType) { + const contextualAwaitedType = getAwaitedTypeNoAlias(contextualType); + return contextualAwaitedType && getUnionType([contextualAwaitedType, createPromiseLikeType(contextualAwaitedType)]); + } + return undefined; + } + + function getContextualTypeForYieldOperand(node: YieldExpression, contextFlags: ContextFlags | undefined): Type | undefined { + const func = getContainingFunction(node); + if (func) { + const functionFlags = getFunctionFlags(func); + let contextualReturnType = getContextualReturnType(func, contextFlags); + if (contextualReturnType) { + const isAsyncGenerator = (functionFlags & FunctionFlags.Async) !== 0; + if (!node.asteriskToken && contextualReturnType.flags & TypeFlags.Union) { + contextualReturnType = filterType(contextualReturnType, type => !!getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, type, isAsyncGenerator)); + } + if (node.asteriskToken) { + const iterationTypes = getIterationTypesOfGeneratorFunctionReturnType(contextualReturnType, isAsyncGenerator); + const yieldType = iterationTypes?.yieldType ?? silentNeverType; + const returnType = getContextualType(node, contextFlags) ?? silentNeverType; + const nextType = iterationTypes?.nextType ?? unknownType; + const generatorType = createGeneratorType(yieldType, returnType, nextType, /*isAsyncGenerator*/ false); + if (isAsyncGenerator) { + const asyncGeneratorType = createGeneratorType(yieldType, returnType, nextType, /*isAsyncGenerator*/ true); + return getUnionType([generatorType, asyncGeneratorType]); + } + return generatorType; + } + return getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Yield, contextualReturnType, isAsyncGenerator); + } + } + + return undefined; + } + + function isInParameterInitializerBeforeContainingFunction(node: Node) { + let inBindingInitializer = false; + while (node.parent && !isFunctionLike(node.parent)) { + if (isParameter(node.parent) && (inBindingInitializer || node.parent.initializer === node)) { + return true; + } + if (isBindingElement(node.parent) && node.parent.initializer === node) { + inBindingInitializer = true; + } + + node = node.parent; + } + + return false; + } + + function getContextualIterationType(kind: IterationTypeKind, functionDecl: SignatureDeclaration): Type | undefined { + const isAsync = !!(getFunctionFlags(functionDecl) & FunctionFlags.Async); + const contextualReturnType = getContextualReturnType(functionDecl, /*contextFlags*/ undefined); + if (contextualReturnType) { + return getIterationTypeOfGeneratorFunctionReturnType(kind, contextualReturnType, isAsync) + || undefined; + } + + return undefined; + } + + function getContextualReturnType(functionDecl: SignatureDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + // If the containing function has a return type annotation, is a constructor, or is a get accessor whose + // corresponding set accessor has a type annotation, return statements in the function are contextually typed + const returnType = getReturnTypeFromAnnotation(functionDecl); + if (returnType) { + return returnType; + } + // Otherwise, if the containing function is contextually typed by a function type with exactly one call signature + // and that call signature is non-generic, return statements are contextually typed by the return type of the signature + const signature = getContextualSignatureForFunctionLikeDeclaration(functionDecl as FunctionExpression); + if (signature && !isResolvingReturnTypeOfSignature(signature)) { + const returnType = getReturnTypeOfSignature(signature); + const functionFlags = getFunctionFlags(functionDecl); + if (functionFlags & FunctionFlags.Generator) { + return filterType(returnType, t => { + return !!(t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.InstantiableNonPrimitive)) || checkGeneratorInstantiationAssignabilityToReturnType(t, functionFlags, /*errorNode*/ undefined); + }); + } + if (functionFlags & FunctionFlags.Async) { + return filterType(returnType, t => { + return !!(t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.InstantiableNonPrimitive)) || !!getAwaitedTypeOfPromise(t); + }); + } + return returnType; + } + const iife = getImmediatelyInvokedFunctionExpression(functionDecl); + if (iife) { + return getContextualType(iife, contextFlags); + } + return undefined; + } + + // In a typed function call, an argument or substitution expression is contextually typed by the type of the corresponding parameter. + function getContextualTypeForArgument(callTarget: CallLikeExpression, arg: Expression): Type | undefined { + const args = getEffectiveCallArguments(callTarget); + const argIndex = args.indexOf(arg); // -1 for e.g. the expression of a CallExpression, or the tag of a TaggedTemplateExpression + return argIndex === -1 ? undefined : getContextualTypeForArgumentAtIndex(callTarget, argIndex); + } + + function getContextualTypeForArgumentAtIndex(callTarget: CallLikeExpression, argIndex: number): Type { + if (isImportCall(callTarget)) { + return argIndex === 0 ? stringType : + argIndex === 1 ? getGlobalImportCallOptionsType(/*reportErrors*/ false) : + anyType; + } + + // If we're already in the process of resolving the given signature, don't resolve again as + // that could cause infinite recursion. Instead, return anySignature. + const signature = getNodeLinks(callTarget).resolvedSignature === resolvingSignature ? resolvingSignature : getResolvedSignature(callTarget); + + if (isJsxOpeningLikeElement(callTarget) && argIndex === 0) { + return getEffectiveFirstArgumentForJsxSignature(signature, callTarget); + } + const restIndex = signature.parameters.length - 1; + return signatureHasRestParameter(signature) && argIndex >= restIndex ? + getIndexedAccessType(getTypeOfSymbol(signature.parameters[restIndex]), getNumberLiteralType(argIndex - restIndex), AccessFlags.Contextual) : + getTypeAtPosition(signature, argIndex); + } + + function getContextualTypeForDecorator(decorator: Decorator): Type | undefined { + const signature = getDecoratorCallSignature(decorator); + return signature ? getOrCreateTypeFromSignature(signature) : undefined; + } + + function getContextualTypeForSubstitutionExpression(template: TemplateExpression, substitutionExpression: Expression) { + if (template.parent.kind === SyntaxKind.TaggedTemplateExpression) { + return getContextualTypeForArgument(template.parent as TaggedTemplateExpression, substitutionExpression); + } + + return undefined; + } + + function getContextualTypeForBinaryOperand(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const binaryExpression = node.parent as BinaryExpression; + const { left, operatorToken, right } = binaryExpression; + switch (operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: + case SyntaxKind.BarBarEqualsToken: + case SyntaxKind.QuestionQuestionEqualsToken: + return node === right ? getContextualTypeForAssignmentDeclaration(binaryExpression) : undefined; + case SyntaxKind.BarBarToken: + case SyntaxKind.QuestionQuestionToken: + // When an || expression has a contextual type, the operands are contextually typed by that type, except + // when that type originates in a binding pattern, the right operand is contextually typed by the type of + // the left operand. When an || expression has no contextual type, the right operand is contextually typed + // by the type of the left operand, except for the special case of Javascript declarations of the form + // `namespace.prop = namespace.prop || {}`. + const type = getContextualType(binaryExpression, contextFlags); + return node === right && (type && type.pattern || !type && !isDefaultedExpandoInitializer(binaryExpression)) ? + getTypeOfExpression(left) : type; + case SyntaxKind.AmpersandAmpersandToken: + case SyntaxKind.CommaToken: + return node === right ? getContextualType(binaryExpression, contextFlags) : undefined; + default: + return undefined; + } + } + + /** + * Try to find a resolved symbol for an expression without also resolving its type, as + * getSymbolAtLocation would (as that could be reentrant into contextual typing) + */ + function getSymbolForExpression(e: Expression) { + if (canHaveSymbol(e) && e.symbol) { + return e.symbol; + } + if (isIdentifier(e)) { + return getResolvedSymbol(e); + } + if (isPropertyAccessExpression(e)) { + const lhsType = getTypeOfExpression(e.expression); + return isPrivateIdentifier(e.name) ? tryGetPrivateIdentifierPropertyOfType(lhsType, e.name) : getPropertyOfType(lhsType, e.name.escapedText); + } + if (isElementAccessExpression(e)) { + const propType = checkExpressionCached(e.argumentExpression); + if (!isTypeUsableAsPropertyName(propType)) { + return undefined; + } + const lhsType = getTypeOfExpression(e.expression); + return getPropertyOfType(lhsType, getPropertyNameFromType(propType)); + } + return undefined; + + function tryGetPrivateIdentifierPropertyOfType(type: Type, id: PrivateIdentifier) { + const lexicallyScopedSymbol = lookupSymbolForPrivateIdentifierDeclaration(id.escapedText, id); + return lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(type, lexicallyScopedSymbol); + } + } + + // In an assignment expression, the right operand is contextually typed by the type of the left operand. + // Don't do this for assignment declarations unless there is a type tag on the assignment, to avoid circularity from checking the right operand. + function getContextualTypeForAssignmentDeclaration(binaryExpression: BinaryExpression): Type | undefined { + const kind = getAssignmentDeclarationKind(binaryExpression); + switch (kind) { + case AssignmentDeclarationKind.None: + case AssignmentDeclarationKind.ThisProperty: + const lhsSymbol = getSymbolForExpression(binaryExpression.left); + const decl = lhsSymbol && lhsSymbol.valueDeclaration; + // Unannotated, uninitialized property declarations have a type implied by their usage in the constructor. + // We avoid calling back into `getTypeOfExpression` and reentering contextual typing to avoid a bogus circularity error in that case. + if (decl && (isPropertyDeclaration(decl) || isPropertySignature(decl))) { + const overallAnnotation = getEffectiveTypeAnnotationNode(decl); + return (overallAnnotation && instantiateType(getTypeFromTypeNode(overallAnnotation), getSymbolLinks(lhsSymbol).mapper)) || + (isPropertyDeclaration(decl) ? decl.initializer && getTypeOfExpression(binaryExpression.left) : undefined); + } + if (kind === AssignmentDeclarationKind.None) { + return getTypeOfExpression(binaryExpression.left); + } + return getContextualTypeForThisPropertyAssignment(binaryExpression); + case AssignmentDeclarationKind.Property: + if (isPossiblyAliasedThisProperty(binaryExpression, kind)) { + return getContextualTypeForThisPropertyAssignment(binaryExpression); + } + // If `binaryExpression.left` was assigned a symbol, then this is a new declaration; otherwise it is an assignment to an existing declaration. + // See `bindStaticPropertyAssignment` in `binder.ts`. + else if (!canHaveSymbol(binaryExpression.left) || !binaryExpression.left.symbol) { + return getTypeOfExpression(binaryExpression.left); + } + else { + const decl = binaryExpression.left.symbol.valueDeclaration; + if (!decl) { + return undefined; + } + const lhs = cast(binaryExpression.left, isAccessExpression); + const overallAnnotation = getEffectiveTypeAnnotationNode(decl); + if (overallAnnotation) { + return getTypeFromTypeNode(overallAnnotation); + } + else if (isIdentifier(lhs.expression)) { + const id = lhs.expression; + const parentSymbol = resolveName(id, id.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (parentSymbol) { + const annotated = parentSymbol.valueDeclaration && getEffectiveTypeAnnotationNode(parentSymbol.valueDeclaration); + if (annotated) { + const nameStr = getElementOrPropertyAccessName(lhs); + if (nameStr !== undefined) { + return getTypeOfPropertyOfContextualType(getTypeFromTypeNode(annotated), nameStr); + } + } + return undefined; + } + } + return isInJSFile(decl) || decl === binaryExpression.left ? undefined : getTypeOfExpression(binaryExpression.left); + } + case AssignmentDeclarationKind.ExportsProperty: + case AssignmentDeclarationKind.Prototype: + case AssignmentDeclarationKind.PrototypeProperty: + case AssignmentDeclarationKind.ModuleExports: + let valueDeclaration: Declaration | undefined; + if (kind !== AssignmentDeclarationKind.ModuleExports) { + valueDeclaration = canHaveSymbol(binaryExpression.left) ? binaryExpression.left.symbol?.valueDeclaration : undefined; + } + valueDeclaration ||= binaryExpression.symbol?.valueDeclaration; + const annotated = valueDeclaration && getEffectiveTypeAnnotationNode(valueDeclaration); + return annotated ? getTypeFromTypeNode(annotated) : undefined; + case AssignmentDeclarationKind.ObjectDefinePropertyValue: + case AssignmentDeclarationKind.ObjectDefinePropertyExports: + case AssignmentDeclarationKind.ObjectDefinePrototypeProperty: + return Debug.fail("Does not apply"); + default: + return Debug.assertNever(kind); + } + } + + function isPossiblyAliasedThisProperty(declaration: BinaryExpression, kind = getAssignmentDeclarationKind(declaration)) { + if (kind === AssignmentDeclarationKind.ThisProperty) { + return true; + } + if (!isInJSFile(declaration) || kind !== AssignmentDeclarationKind.Property || !isIdentifier((declaration.left as AccessExpression).expression)) { + return false; + } + const name = ((declaration.left as AccessExpression).expression as Identifier).escapedText; + const symbol = resolveName(declaration.left, name, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true, /*excludeGlobals*/ true); + return isThisInitializedDeclaration(symbol?.valueDeclaration); + } + + function getContextualTypeForThisPropertyAssignment(binaryExpression: BinaryExpression): Type | undefined { + if (!binaryExpression.symbol) return getTypeOfExpression(binaryExpression.left); + if (binaryExpression.symbol.valueDeclaration) { + const annotated = getEffectiveTypeAnnotationNode(binaryExpression.symbol.valueDeclaration); + if (annotated) { + const type = getTypeFromTypeNode(annotated); + if (type) { + return type; + } + } + } + const thisAccess = cast(binaryExpression.left, isAccessExpression); + if (!isObjectLiteralMethod(getThisContainer(thisAccess.expression, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false))) { + return undefined; + } + const thisType = checkThisExpression(thisAccess.expression); + const nameStr = getElementOrPropertyAccessName(thisAccess); + return nameStr !== undefined && getTypeOfPropertyOfContextualType(thisType, nameStr) || undefined; + } + + function isCircularMappedProperty(symbol: Symbol) { + return !!(getCheckFlags(symbol) & CheckFlags.Mapped && !(symbol as MappedSymbol).links.type && findResolutionCycleStartIndex(symbol, TypeSystemPropertyName.Type) >= 0); + } + + function getTypeOfPropertyOfContextualType(type: Type, name: __String, nameType?: Type) { + return mapType(type, t => { + if (isGenericMappedType(t) && !t.declaration.nameType) { + const constraint = getConstraintTypeFromMappedType(t); + const constraintOfConstraint = getBaseConstraintOfType(constraint) || constraint; + const propertyNameType = nameType || getStringLiteralType(unescapeLeadingUnderscores(name)); + if (isTypeAssignableTo(propertyNameType, constraintOfConstraint)) { + return substituteIndexedMappedType(t, propertyNameType); + } + } + else if (t.flags & TypeFlags.StructuredType) { + const prop = getPropertyOfType(t, name); + if (prop) { + return isCircularMappedProperty(prop) ? undefined : removeMissingType(getTypeOfSymbol(prop), !!(prop.flags & SymbolFlags.Optional)); + } + if (isTupleType(t) && isNumericLiteralName(name) && +name >= 0) { + const restType = getElementTypeOfSliceOfTupleType(t, t.target.fixedLength, /*endSkipCount*/ 0, /*writing*/ false, /*noReductions*/ true); + if (restType) { + return restType; + } + } + return findApplicableIndexInfo(getIndexInfosOfStructuredType(t), nameType || getStringLiteralType(unescapeLeadingUnderscores(name)))?.type; + } + return undefined; + }, /*noReductions*/ true); + } + + // In an object literal contextually typed by a type T, the contextual type of a property assignment is the type of + // the matching property in T, if one exists. Otherwise, it is the type of the numeric index signature in T, if one + // exists. Otherwise, it is the type of the string index signature in T, if one exists. + function getContextualTypeForObjectLiteralMethod(node: MethodDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + Debug.assert(isObjectLiteralMethod(node)); + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return undefined; + } + return getContextualTypeForObjectLiteralElement(node, contextFlags); + } + + function getContextualTypeForObjectLiteralElement(element: ObjectLiteralElementLike, contextFlags: ContextFlags | undefined) { + const objectLiteral = element.parent as ObjectLiteralExpression; + const propertyAssignmentType = isPropertyAssignment(element) && getContextualTypeForVariableLikeDeclaration(element, contextFlags); + if (propertyAssignmentType) { + return propertyAssignmentType; + } + const type = getApparentTypeOfContextualType(objectLiteral, contextFlags); + if (type) { + if (hasBindableName(element)) { + // For a (non-symbol) computed property, there is no reason to look up the name + // in the type. It will just be "__computed", which does not appear in any + // SymbolTable. + const symbol = getSymbolOfDeclaration(element); + return getTypeOfPropertyOfContextualType(type, symbol.escapedName, getSymbolLinks(symbol).nameType); + } + if (hasDynamicName(element)) { + const name = getNameOfDeclaration(element); + if (name && isComputedPropertyName(name)) { + const exprType = checkExpression(name.expression); + const propType = isTypeUsableAsPropertyName(exprType) && getTypeOfPropertyOfContextualType(type, getPropertyNameFromType(exprType)); + if (propType) { + return propType; + } + } + } + if (element.name) { + const nameType = getLiteralTypeFromPropertyName(element.name); + // We avoid calling getApplicableIndexInfo here because it performs potentially expensive intersection reduction. + return mapType(type, t => findApplicableIndexInfo(getIndexInfosOfStructuredType(t), nameType)?.type, /*noReductions*/ true); + } + } + return undefined; + } + + function getSpreadIndices(elements: readonly Node[]) { + let first, last; + for (let i = 0; i < elements.length; i++) { + if (isSpreadElement(elements[i])) { + first ??= i; + last = i; + } + } + return { first, last }; + } + + function getContextualTypeForElementExpression(type: Type | undefined, index: number, length?: number, firstSpreadIndex?: number, lastSpreadIndex?: number): Type | undefined { + return type && mapType(type, t => { + if (isTupleType(t)) { + // If index is before any spread element and within the fixed part of the contextual tuple type, return + // the type of the contextual tuple element. + if ((firstSpreadIndex === undefined || index < firstSpreadIndex) && index < t.target.fixedLength) { + return removeMissingType(getTypeArguments(t)[index], !!(t.target.elementFlags[index] && ElementFlags.Optional)); + } + // When the length is known and the index is after all spread elements we compute the offset from the element + // to the end and the number of ending fixed elements in the contextual tuple type. + const offset = length !== undefined && (lastSpreadIndex === undefined || index > lastSpreadIndex) ? length - index : 0; + const fixedEndLength = offset > 0 && (t.target.combinedFlags & ElementFlags.Variable) ? getEndElementCount(t.target, ElementFlags.Fixed) : 0; + // If the offset is within the ending fixed part of the contextual tuple type, return the type of the contextual + // tuple element. + if (offset > 0 && offset <= fixedEndLength) { + return getTypeArguments(t)[getTypeReferenceArity(t) - offset]; + } + // Return a union of the possible contextual element types with no subtype reduction. + return getElementTypeOfSliceOfTupleType(t, firstSpreadIndex === undefined ? t.target.fixedLength : Math.min(t.target.fixedLength, firstSpreadIndex), length === undefined || lastSpreadIndex === undefined ? fixedEndLength : Math.min(fixedEndLength, length - lastSpreadIndex), /*writing*/ false, /*noReductions*/ true); + } + // If element index is known and a contextual property with that name exists, return it. Otherwise return the + // iterated or element type of the contextual type. + return (!firstSpreadIndex || index < firstSpreadIndex) && getTypeOfPropertyOfContextualType(t, "" + index as __String) || + getIteratedTypeOrElementType(IterationUse.Element, t, undefinedType, /*errorNode*/ undefined, /*checkAssignability*/ false); + }, /*noReductions*/ true); + } + + // In a contextually typed conditional expression, the true/false expressions are contextually typed by the same type. + function getContextualTypeForConditionalOperand(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const conditional = node.parent as ConditionalExpression; + return node === conditional.whenTrue || node === conditional.whenFalse ? getContextualType(conditional, contextFlags) : undefined; + } + + function getContextualTypeForChildJsxExpression(node: JsxElement, child: JsxChild, contextFlags: ContextFlags | undefined) { + const attributesType = getApparentTypeOfContextualType(node.openingElement.attributes, contextFlags); + // JSX expression is in children of JSX Element, we will look for an "children" attribute (we get the name from JSX.ElementAttributesProperty) + const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + if (!(attributesType && !isTypeAny(attributesType) && jsxChildrenPropertyName && jsxChildrenPropertyName !== "")) { + return undefined; + } + const realChildren = getSemanticJsxChildren(node.children); + const childIndex = realChildren.indexOf(child); + const childFieldType = getTypeOfPropertyOfContextualType(attributesType, jsxChildrenPropertyName); + return childFieldType && (realChildren.length === 1 ? childFieldType : mapType(childFieldType, t => { + if (isArrayLikeType(t)) { + return getIndexedAccessType(t, getNumberLiteralType(childIndex)); + } + else { + return t; + } + }, /*noReductions*/ true)); + } + + function getContextualTypeForJsxExpression(node: JsxExpression, contextFlags: ContextFlags | undefined): Type | undefined { + const exprParent = node.parent; + return isJsxAttributeLike(exprParent) + ? getContextualType(node, contextFlags) + : isJsxElement(exprParent) + ? getContextualTypeForChildJsxExpression(exprParent, node, contextFlags) + : undefined; + } + + function getContextualTypeForJsxAttribute(attribute: JsxAttribute | JsxSpreadAttribute, contextFlags: ContextFlags | undefined): Type | undefined { + // When we trying to resolve JsxOpeningLikeElement as a stateless function element, we will already give its attributes a contextual type + // which is a type of the parameter of the signature we are trying out. + // If there is no contextual type (e.g. we are trying to resolve stateful component), get attributes type from resolving element's tagName + if (isJsxAttribute(attribute)) { + const attributesType = getApparentTypeOfContextualType(attribute.parent, contextFlags); + if (!attributesType || isTypeAny(attributesType)) { + return undefined; + } + return getTypeOfPropertyOfContextualType(attributesType, getEscapedTextOfJsxAttributeName(attribute.name)); + } + else { + return getContextualType(attribute.parent, contextFlags); + } + } + + // Return true if the given expression is possibly a discriminant value. We limit the kinds of + // expressions we check to those that don't depend on their contextual type in order not to cause + // recursive (and possibly infinite) invocations of getContextualType. + function isPossiblyDiscriminantValue(node: Expression): boolean { + switch (node.kind) { + case SyntaxKind.StringLiteral: + case SyntaxKind.NumericLiteral: + case SyntaxKind.BigIntLiteral: + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.TemplateExpression: + case SyntaxKind.TrueKeyword: + case SyntaxKind.FalseKeyword: + case SyntaxKind.NullKeyword: + case SyntaxKind.Identifier: + case SyntaxKind.UndefinedKeyword: + return true; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ParenthesizedExpression: + return isPossiblyDiscriminantValue((node as PropertyAccessExpression | ParenthesizedExpression).expression); + case SyntaxKind.JsxExpression: + return !(node as JsxExpression).expression || isPossiblyDiscriminantValue((node as JsxExpression).expression!); + } + return false; + } + + function discriminateContextualTypeByObjectMembers(node: ObjectLiteralExpression, contextualType: UnionType) { + const key = `D${getNodeId(node)},${getTypeId(contextualType)}`; + return getCachedType(key) ?? setCachedType( + key, + getMatchingUnionConstituentForObjectLiteral(contextualType, node) ?? discriminateTypeByDiscriminableItems( + contextualType, + concatenate( + map( + filter(node.properties, (p): p is PropertyAssignment | ShorthandPropertyAssignment => { + if (!p.symbol) { + return false; + } + if (p.kind === SyntaxKind.PropertyAssignment) { + return isPossiblyDiscriminantValue(p.initializer) && isDiscriminantProperty(contextualType, p.symbol.escapedName); + } + if (p.kind === SyntaxKind.ShorthandPropertyAssignment) { + return isDiscriminantProperty(contextualType, p.symbol.escapedName); + } + return false; + }), + prop => ([() => getContextFreeTypeOfExpression(prop.kind === SyntaxKind.PropertyAssignment ? prop.initializer : prop.name), prop.symbol.escapedName] as const), + ), + map( + filter(getPropertiesOfType(contextualType), s => !!(s.flags & SymbolFlags.Optional) && !!node?.symbol?.members && !node.symbol.members.has(s.escapedName) && isDiscriminantProperty(contextualType, s.escapedName)), + s => [() => undefinedType, s.escapedName] as const, + ), + ), + isTypeAssignableTo, + ), + ); + } + + function discriminateContextualTypeByJSXAttributes(node: JsxAttributes, contextualType: UnionType) { + const key = `D${getNodeId(node)},${getTypeId(contextualType)}`; + const cached = getCachedType(key); + if (cached) return cached; + const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + return setCachedType( + key, + discriminateTypeByDiscriminableItems( + contextualType, + concatenate( + map( + filter(node.properties, p => !!p.symbol && p.kind === SyntaxKind.JsxAttribute && isDiscriminantProperty(contextualType, p.symbol.escapedName) && (!p.initializer || isPossiblyDiscriminantValue(p.initializer))), + prop => ([!(prop as JsxAttribute).initializer ? (() => trueType) : (() => getContextFreeTypeOfExpression((prop as JsxAttribute).initializer!)), prop.symbol.escapedName] as const), + ), + map( + filter(getPropertiesOfType(contextualType), s => { + if (!(s.flags & SymbolFlags.Optional) || !node?.symbol?.members) { + return false; + } + const element = node.parent.parent; + if (s.escapedName === jsxChildrenPropertyName && isJsxElement(element) && getSemanticJsxChildren(element.children).length) { + return false; + } + return !node.symbol.members.has(s.escapedName) && isDiscriminantProperty(contextualType, s.escapedName); + }), + s => [() => undefinedType, s.escapedName] as const, + ), + ), + isTypeAssignableTo, + ), + ); + } + + // Return the contextual type for a given expression node. During overload resolution, a contextual type may temporarily + // be "pushed" onto a node using the contextualType property. + function getApparentTypeOfContextualType(node: Expression | MethodDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + const contextualType = isObjectLiteralMethod(node) ? + getContextualTypeForObjectLiteralMethod(node, contextFlags) : + getContextualType(node, contextFlags); + const instantiatedType = instantiateContextualType(contextualType, node, contextFlags); + if (instantiatedType && !(contextFlags && contextFlags & ContextFlags.NoConstraints && instantiatedType.flags & TypeFlags.TypeVariable)) { + const apparentType = mapType( + instantiatedType, + // When obtaining apparent type of *contextual* type we don't want to get apparent type of mapped types. + // That would evaluate mapped types with array or tuple type constraints too eagerly + // and thus it would prevent `getTypeOfPropertyOfContextualType` from obtaining per-position contextual type for elements of array literal expressions. + // Apparent type of other mapped types is already the mapped type itself so we can just avoid calling `getApparentType` here for all mapped types. + t => getObjectFlags(t) & ObjectFlags.Mapped ? t : getApparentType(t), + /*noReductions*/ true, + ); + return apparentType.flags & TypeFlags.Union && isObjectLiteralExpression(node) ? discriminateContextualTypeByObjectMembers(node, apparentType as UnionType) : + apparentType.flags & TypeFlags.Union && isJsxAttributes(node) ? discriminateContextualTypeByJSXAttributes(node, apparentType as UnionType) : + apparentType; + } + } + + // If the given contextual type contains instantiable types and if a mapper representing + // return type inferences is available, instantiate those types using that mapper. + function instantiateContextualType(contextualType: Type | undefined, node: Node, contextFlags: ContextFlags | undefined): Type | undefined { + if (contextualType && maybeTypeOfKind(contextualType, TypeFlags.Instantiable)) { + const inferenceContext = getInferenceContext(node); + // If no inferences have been made, and none of the type parameters for which we are inferring + // specify default types, nothing is gained from instantiating as type parameters would just be + // replaced with their constraints similar to the apparent type. + if (inferenceContext && contextFlags! & ContextFlags.Signature && some(inferenceContext.inferences, hasInferenceCandidatesOrDefault)) { + // For contextual signatures we incorporate all inferences made so far, e.g. from return + // types as well as arguments to the left in a function call. + return instantiateInstantiableTypes(contextualType, inferenceContext.nonFixingMapper); + } + if (inferenceContext?.returnMapper) { + // For other purposes (e.g. determining whether to produce literal types) we only + // incorporate inferences made from the return type in a function call. We remove + // the 'boolean' type from the contextual type such that contextually typed boolean + // literals actually end up widening to 'boolean' (see #48363). + const type = instantiateInstantiableTypes(contextualType, inferenceContext.returnMapper); + return type.flags & TypeFlags.Union && containsType((type as UnionType).types, regularFalseType) && containsType((type as UnionType).types, regularTrueType) ? + filterType(type, t => t !== regularFalseType && t !== regularTrueType) : + type; + } + } + return contextualType; + } + + // This function is similar to instantiateType, except that (a) it only instantiates types that + // are classified as instantiable (i.e. it doesn't instantiate object types), and (b) it performs + // no reductions on instantiated union types. + function instantiateInstantiableTypes(type: Type, mapper: TypeMapper): Type { + if (type.flags & TypeFlags.Instantiable) { + return instantiateType(type, mapper); + } + if (type.flags & TypeFlags.Union) { + return getUnionType(map((type as UnionType).types, t => instantiateInstantiableTypes(t, mapper)), UnionReduction.None); + } + if (type.flags & TypeFlags.Intersection) { + return getIntersectionType(map((type as IntersectionType).types, t => instantiateInstantiableTypes(t, mapper))); + } + return type; + } + + /** + * Whoa! Do you really want to use this function? + * + * Unless you're trying to get the *non-apparent* type for a + * value-literal type or you're authoring relevant portions of this algorithm, + * you probably meant to use 'getApparentTypeOfContextualType'. + * Otherwise this may not be very useful. + * + * In cases where you *are* working on this function, you should understand + * when it is appropriate to use 'getContextualType' and 'getApparentTypeOfContextualType'. + * + * - Use 'getContextualType' when you are simply going to propagate the result to the expression. + * - Use 'getApparentTypeOfContextualType' when you're going to need the members of the type. + * + * @param node the expression whose contextual type will be returned. + * @returns the contextual type of an expression. + */ + function getContextualType(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return undefined; + } + // Cached contextual types are obtained with no ContextFlags, so we can only consult them for + // requests with no ContextFlags. + const index = findContextualNode(node, /*includeCaches*/ !contextFlags); + if (index >= 0) { + return contextualTypes[index]; + } + const { parent } = node; + switch (parent.kind) { + case SyntaxKind.VariableDeclaration: + case SyntaxKind.Parameter: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + case SyntaxKind.BindingElement: + return getContextualTypeForInitializerExpression(node, contextFlags); + case SyntaxKind.ArrowFunction: + case SyntaxKind.ReturnStatement: + return getContextualTypeForReturnExpression(node, contextFlags); + case SyntaxKind.YieldExpression: + return getContextualTypeForYieldOperand(parent as YieldExpression, contextFlags); + case SyntaxKind.AwaitExpression: + return getContextualTypeForAwaitOperand(parent as AwaitExpression, contextFlags); + case SyntaxKind.CallExpression: + case SyntaxKind.NewExpression: + return getContextualTypeForArgument(parent as CallExpression | NewExpression | Decorator, node); + case SyntaxKind.Decorator: + return getContextualTypeForDecorator(parent as Decorator); + case SyntaxKind.TypeAssertionExpression: + case SyntaxKind.AsExpression: + return isConstTypeReference((parent as AssertionExpression).type) ? getContextualType(parent as AssertionExpression, contextFlags) : getTypeFromTypeNode((parent as AssertionExpression).type); + case SyntaxKind.BinaryExpression: + return getContextualTypeForBinaryOperand(node, contextFlags); + case SyntaxKind.PropertyAssignment: + case SyntaxKind.ShorthandPropertyAssignment: + return getContextualTypeForObjectLiteralElement(parent as PropertyAssignment | ShorthandPropertyAssignment, contextFlags); + case SyntaxKind.SpreadAssignment: + return getContextualType(parent.parent as ObjectLiteralExpression, contextFlags); + case SyntaxKind.ArrayLiteralExpression: { + const arrayLiteral = parent as ArrayLiteralExpression; + const type = getApparentTypeOfContextualType(arrayLiteral, contextFlags); + const elementIndex = indexOfNode(arrayLiteral.elements, node); + const spreadIndices = getNodeLinks(arrayLiteral).spreadIndices ??= getSpreadIndices(arrayLiteral.elements); + return getContextualTypeForElementExpression(type, elementIndex, arrayLiteral.elements.length, spreadIndices.first, spreadIndices.last); + } + case SyntaxKind.ConditionalExpression: + return getContextualTypeForConditionalOperand(node, contextFlags); + case SyntaxKind.TemplateSpan: + Debug.assert(parent.parent.kind === SyntaxKind.TemplateExpression); + return getContextualTypeForSubstitutionExpression(parent.parent as TemplateExpression, node); + case SyntaxKind.ParenthesizedExpression: { + if (isInJSFile(parent)) { + if (isJSDocSatisfiesExpression(parent)) { + return getTypeFromTypeNode(getJSDocSatisfiesExpressionType(parent)); + } + // Like in `checkParenthesizedExpression`, an `/** @type {xyz} */` comment before a parenthesized expression acts as a type cast. + const typeTag = getJSDocTypeTag(parent); + if (typeTag && !isConstTypeReference(typeTag.typeExpression.type)) { + return getTypeFromTypeNode(typeTag.typeExpression.type); + } + } + return getContextualType(parent as ParenthesizedExpression, contextFlags); + } + case SyntaxKind.NonNullExpression: + return getContextualType(parent as NonNullExpression, contextFlags); + case SyntaxKind.SatisfiesExpression: + return getTypeFromTypeNode((parent as SatisfiesExpression).type); + case SyntaxKind.ExportAssignment: + return tryGetTypeFromEffectiveTypeNode(parent as ExportAssignment); + case SyntaxKind.JsxExpression: + return getContextualTypeForJsxExpression(parent as JsxExpression, contextFlags); + case SyntaxKind.JsxAttribute: + case SyntaxKind.JsxSpreadAttribute: + return getContextualTypeForJsxAttribute(parent as JsxAttribute | JsxSpreadAttribute, contextFlags); + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.JsxSelfClosingElement: + return getContextualJsxElementAttributesType(parent as JsxOpeningLikeElement, contextFlags); + case SyntaxKind.ImportAttribute: + return getContextualImportAttributeType(parent as ImportAttribute); + } + return undefined; + } + + function pushCachedContextualType(node: Expression) { + pushContextualType(node, getContextualType(node, /*contextFlags*/ undefined), /*isCache*/ true); + } + + function pushContextualType(node: Expression, type: Type | undefined, isCache: boolean) { + contextualTypeNodes[contextualTypeCount] = node; + contextualTypes[contextualTypeCount] = type; + contextualIsCache[contextualTypeCount] = isCache; + contextualTypeCount++; + } + + function popContextualType() { + contextualTypeCount--; + } + + function findContextualNode(node: Node, includeCaches: boolean) { + for (let i = contextualTypeCount - 1; i >= 0; i--) { + if (node === contextualTypeNodes[i] && (includeCaches || !contextualIsCache[i])) { + return i; + } + } + return -1; + } + + function pushInferenceContext(node: Node, inferenceContext: InferenceContext | undefined) { + inferenceContextNodes[inferenceContextCount] = node; + inferenceContexts[inferenceContextCount] = inferenceContext; + inferenceContextCount++; + } + + function popInferenceContext() { + inferenceContextCount--; + } + + function getInferenceContext(node: Node) { + for (let i = inferenceContextCount - 1; i >= 0; i--) { + if (isNodeDescendantOf(node, inferenceContextNodes[i])) { + return inferenceContexts[i]; + } + } + } + + function getContextualImportAttributeType(node: ImportAttribute) { + return getTypeOfPropertyOfContextualType(getGlobalImportAttributesType(/*reportErrors*/ false), getNameFromImportAttribute(node)); + } + + function getContextualJsxElementAttributesType(node: JsxOpeningLikeElement, contextFlags: ContextFlags | undefined) { + if (isJsxOpeningElement(node) && contextFlags !== ContextFlags.Completions) { + const index = findContextualNode(node.parent, /*includeCaches*/ !contextFlags); + if (index >= 0) { + // Contextually applied type is moved from attributes up to the outer jsx attributes so when walking up from the children they get hit + // _However_ to hit them from the _attributes_ we must look for them here; otherwise we'll used the declared type + // (as below) instead! + return contextualTypes[index]; + } + } + return getContextualTypeForArgumentAtIndex(node, 0); + } + + function getEffectiveFirstArgumentForJsxSignature(signature: Signature, node: JsxOpeningLikeElement) { + return getJsxReferenceKind(node) !== JsxReferenceKind.Component + ? getJsxPropsTypeFromCallSignature(signature, node) + : getJsxPropsTypeFromClassType(signature, node); + } + + function getJsxPropsTypeFromCallSignature(sig: Signature, context: JsxOpeningLikeElement) { + let propsType = getTypeOfFirstParameterOfSignatureWithFallback(sig, unknownType); + propsType = getJsxManagedAttributesFromLocatedAttributes(context, getJsxNamespaceAt(context), propsType); + const intrinsicAttribs = getJsxType(JsxNames.IntrinsicAttributes, context); + if (!isErrorType(intrinsicAttribs)) { + propsType = intersectTypes(intrinsicAttribs, propsType); + } + return propsType; + } + + function getJsxPropsTypeForSignatureFromMember(sig: Signature, forcedLookupLocation: __String) { + if (sig.compositeSignatures) { + // JSX Elements using the legacy `props`-field based lookup (eg, react class components) need to treat the `props` member as an input + // instead of an output position when resolving the signature. We need to go back to the input signatures of the composite signature, + // get the type of `props` on each return type individually, and then _intersect them_, rather than union them (as would normally occur + // for a union signature). It's an unfortunate quirk of looking in the output of the signature for the type we want to use for the input. + // The default behavior of `getTypeOfFirstParameterOfSignatureWithFallback` when no `props` member name is defined is much more sane. + const results: Type[] = []; + for (const signature of sig.compositeSignatures) { + const instance = getReturnTypeOfSignature(signature); + if (isTypeAny(instance)) { + return instance; + } + const propType = getTypeOfPropertyOfType(instance, forcedLookupLocation); + if (!propType) { + return; + } + results.push(propType); + } + return getIntersectionType(results); // Same result for both union and intersection signatures + } + const instanceType = getReturnTypeOfSignature(sig); + return isTypeAny(instanceType) ? instanceType : getTypeOfPropertyOfType(instanceType, forcedLookupLocation); + } + + function getStaticTypeOfReferencedJsxConstructor(context: JsxOpeningLikeElement) { + if (isJsxIntrinsicTagName(context.tagName)) { + const result = getIntrinsicAttributesTypeFromJsxOpeningLikeElement(context); + const fakeSignature = createSignatureForJSXIntrinsic(context, result); + return getOrCreateTypeFromSignature(fakeSignature); + } + const tagType = checkExpressionCached(context.tagName); + if (tagType.flags & TypeFlags.StringLiteral) { + const result = getIntrinsicAttributesTypeFromStringLiteralType(tagType as StringLiteralType, context); + if (!result) { + return errorType; + } + const fakeSignature = createSignatureForJSXIntrinsic(context, result); + return getOrCreateTypeFromSignature(fakeSignature); + } + return tagType; + } + + function getJsxManagedAttributesFromLocatedAttributes(context: JsxOpeningLikeElement, ns: Symbol, attributesType: Type) { + const managedSym = getJsxLibraryManagedAttributes(ns); + if (managedSym) { + const ctorType = getStaticTypeOfReferencedJsxConstructor(context); + const result = instantiateAliasOrInterfaceWithDefaults(managedSym, isInJSFile(context), ctorType, attributesType); + if (result) { + return result; + } + } + return attributesType; + } + + function getJsxPropsTypeFromClassType(sig: Signature, context: JsxOpeningLikeElement) { + const ns = getJsxNamespaceAt(context); + const forcedLookupLocation = getJsxElementPropertiesName(ns); + let attributesType = forcedLookupLocation === undefined + // If there is no type ElementAttributesProperty, return the type of the first parameter of the signature, which should be the props type + ? getTypeOfFirstParameterOfSignatureWithFallback(sig, unknownType) + : forcedLookupLocation === "" + // If there is no e.g. 'props' member in ElementAttributesProperty, use the element class type instead + ? getReturnTypeOfSignature(sig) + // Otherwise get the type of the property on the signature return type + : getJsxPropsTypeForSignatureFromMember(sig, forcedLookupLocation); + + if (!attributesType) { + // There is no property named 'props' on this instance type + if (!!forcedLookupLocation && !!length(context.attributes.properties)) { + error(context, Diagnostics.JSX_element_class_does_not_support_attributes_because_it_does_not_have_a_0_property, unescapeLeadingUnderscores(forcedLookupLocation)); + } + return unknownType; + } + + attributesType = getJsxManagedAttributesFromLocatedAttributes(context, ns, attributesType); + + if (isTypeAny(attributesType)) { + // Props is of type 'any' or unknown + return attributesType; + } + else { + // Normal case -- add in IntrinsicClassElements and IntrinsicElements + let apparentAttributesType = attributesType; + const intrinsicClassAttribs = getJsxType(JsxNames.IntrinsicClassAttributes, context); + if (!isErrorType(intrinsicClassAttribs)) { + const typeParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(intrinsicClassAttribs.symbol); + const hostClassType = getReturnTypeOfSignature(sig); + let libraryManagedAttributeType: Type; + if (typeParams) { + // apply JSX.IntrinsicClassElements + const inferredArgs = fillMissingTypeArguments([hostClassType], typeParams, getMinTypeArgumentCount(typeParams), isInJSFile(context)); + libraryManagedAttributeType = instantiateType(intrinsicClassAttribs, createTypeMapper(typeParams, inferredArgs)); + } + // or JSX.IntrinsicClassElements has no generics. + else libraryManagedAttributeType = intrinsicClassAttribs; + apparentAttributesType = intersectTypes(libraryManagedAttributeType, apparentAttributesType); + } + + const intrinsicAttribs = getJsxType(JsxNames.IntrinsicAttributes, context); + if (!isErrorType(intrinsicAttribs)) { + apparentAttributesType = intersectTypes(intrinsicAttribs, apparentAttributesType); + } + + return apparentAttributesType; + } + } + + function getIntersectedSignatures(signatures: readonly Signature[]) { + return getStrictOptionValue(compilerOptions, "noImplicitAny") + ? reduceLeft( + signatures, + (left: Signature | undefined, right) => + left === right || !left ? left + : compareTypeParametersIdentical(left.typeParameters, right!.typeParameters) ? combineSignaturesOfIntersectionMembers(left, right!) + : undefined, + ) + : undefined; + } + + function combineIntersectionThisParam(left: Symbol | undefined, right: Symbol | undefined, mapper: TypeMapper | undefined): Symbol | undefined { + if (!left || !right) { + return left || right; + } + // A signature `this` type might be a read or a write position... It's very possible that it should be invariant + // and we should refuse to merge signatures if there are `this` types and they do not match. However, so as to be + // pessimistic when contextual typing, for now, we'll union the `this` types. + const thisType = getUnionType([getTypeOfSymbol(left), instantiateType(getTypeOfSymbol(right), mapper)]); + return createSymbolWithType(left, thisType); + } + + function combineIntersectionParameters(left: Signature, right: Signature, mapper: TypeMapper | undefined) { + const leftCount = getParameterCount(left); + const rightCount = getParameterCount(right); + const longest = leftCount >= rightCount ? left : right; + const shorter = longest === left ? right : left; + const longestCount = longest === left ? leftCount : rightCount; + const eitherHasEffectiveRest = hasEffectiveRestParameter(left) || hasEffectiveRestParameter(right); + const needsExtraRestElement = eitherHasEffectiveRest && !hasEffectiveRestParameter(longest); + const params = new Array(longestCount + (needsExtraRestElement ? 1 : 0)); + for (let i = 0; i < longestCount; i++) { + let longestParamType = tryGetTypeAtPosition(longest, i)!; + if (longest === right) { + longestParamType = instantiateType(longestParamType, mapper); + } + let shorterParamType = tryGetTypeAtPosition(shorter, i) || unknownType; + if (shorter === right) { + shorterParamType = instantiateType(shorterParamType, mapper); + } + const unionParamType = getUnionType([longestParamType, shorterParamType]); + const isRestParam = eitherHasEffectiveRest && !needsExtraRestElement && i === (longestCount - 1); + const isOptional = i >= getMinArgumentCount(longest) && i >= getMinArgumentCount(shorter); + const leftName = i >= leftCount ? undefined : getParameterNameAtPosition(left, i); + const rightName = i >= rightCount ? undefined : getParameterNameAtPosition(right, i); + + const paramName = leftName === rightName ? leftName : + !leftName ? rightName : + !rightName ? leftName : + undefined; + const paramSymbol = createSymbol( + SymbolFlags.FunctionScopedVariable | (isOptional && !isRestParam ? SymbolFlags.Optional : 0), + paramName || `arg${i}` as __String, + ); + paramSymbol.links.type = isRestParam ? createArrayType(unionParamType) : unionParamType; + params[i] = paramSymbol; + } + if (needsExtraRestElement) { + const restParamSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "args" as __String); + restParamSymbol.links.type = createArrayType(getTypeAtPosition(shorter, longestCount)); + if (shorter === right) { + restParamSymbol.links.type = instantiateType(restParamSymbol.links.type, mapper); + } + params[longestCount] = restParamSymbol; + } + return params; + } + + function combineSignaturesOfIntersectionMembers(left: Signature, right: Signature): Signature { + const typeParams = left.typeParameters || right.typeParameters; + let paramMapper: TypeMapper | undefined; + if (left.typeParameters && right.typeParameters) { + paramMapper = createTypeMapper(right.typeParameters, left.typeParameters); + // We just use the type parameter defaults from the first signature + } + const declaration = left.declaration; + const params = combineIntersectionParameters(left, right, paramMapper); + const thisParam = combineIntersectionThisParam(left.thisParameter, right.thisParameter, paramMapper); + const minArgCount = Math.max(left.minArgumentCount, right.minArgumentCount); + const result = createSignature( + declaration, + typeParams, + thisParam, + params, + /*resolvedReturnType*/ undefined, + /*resolvedTypePredicate*/ undefined, + minArgCount, + (left.flags | right.flags) & SignatureFlags.PropagatingFlags, + ); + result.compositeKind = TypeFlags.Intersection; + result.compositeSignatures = concatenate(left.compositeKind === TypeFlags.Intersection && left.compositeSignatures || [left], [right]); + if (paramMapper) { + result.mapper = left.compositeKind === TypeFlags.Intersection && left.mapper && left.compositeSignatures ? combineTypeMappers(left.mapper, paramMapper) : paramMapper; + } + return result; + } + + // If the given type is an object or union type with a single signature, and if that signature has at + // least as many parameters as the given function, return the signature. Otherwise return undefined. + function getContextualCallSignature(type: Type, node: SignatureDeclaration): Signature | undefined { + const signatures = getSignaturesOfType(type, SignatureKind.Call); + const applicableByArity = filter(signatures, s => !isAritySmaller(s, node)); + return applicableByArity.length === 1 ? applicableByArity[0] : getIntersectedSignatures(applicableByArity); + } + + /** If the contextual signature has fewer parameters than the function expression, do not use it */ + function isAritySmaller(signature: Signature, target: SignatureDeclaration) { + let targetParameterCount = 0; + for (; targetParameterCount < target.parameters.length; targetParameterCount++) { + const param = target.parameters[targetParameterCount]; + if (param.initializer || param.questionToken || param.dotDotDotToken || isJSDocOptionalParameter(param)) { + break; + } + } + if (target.parameters.length && parameterIsThisKeyword(target.parameters[0])) { + targetParameterCount--; + } + return !hasEffectiveRestParameter(signature) && getParameterCount(signature) < targetParameterCount; + } + + function getContextualSignatureForFunctionLikeDeclaration(node: FunctionLikeDeclaration): Signature | undefined { + // Only function expressions, arrow functions, and object literal methods are contextually typed. + return isFunctionExpressionOrArrowFunction(node) || isObjectLiteralMethod(node) + ? getContextualSignature(node as FunctionExpression) + : undefined; + } + + // Return the contextual signature for a given expression node. A contextual type provides a + // contextual signature if it has a single call signature and if that call signature is non-generic. + // If the contextual type is a union type, get the signature from each type possible and if they are + // all identical ignoring their return type, the result is same signature but with return type as + // union type of return types from these signatures + function getContextualSignature(node: FunctionExpression | ArrowFunction | MethodDeclaration): Signature | undefined { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + const typeTagSignature = getSignatureOfTypeTag(node); + if (typeTagSignature) { + return typeTagSignature; + } + const type = getApparentTypeOfContextualType(node, ContextFlags.Signature); + if (!type) { + return undefined; + } + if (!(type.flags & TypeFlags.Union)) { + return getContextualCallSignature(type, node); + } + let signatureList: Signature[] | undefined; + const types = (type as UnionType).types; + for (const current of types) { + const signature = getContextualCallSignature(current, node); + if (signature) { + if (!signatureList) { + // This signature will contribute to contextual union signature + signatureList = [signature]; + } + else if (!compareSignaturesIdentical(signatureList[0], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ true, /*ignoreReturnTypes*/ true, compareTypesIdentical)) { + // Signatures aren't identical, do not use + return undefined; + } + else { + // Use this signature for contextual union signature + signatureList.push(signature); + } + } + } + // Result is union of signatures collected (return type is union of return types of this signature set) + if (signatureList) { + return signatureList.length === 1 ? signatureList[0] : createUnionSignature(signatureList[0], signatureList); + } + } + + function checkGrammarRegularExpressionLiteral(node: RegularExpressionLiteral) { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile) && !node.isUnterminated) { + let lastError: DiagnosticWithLocation | undefined; + scanner ??= createScanner(ScriptTarget.ESNext, /*skipTrivia*/ true); + scanner.setScriptTarget(sourceFile.languageVersion); + scanner.setLanguageVariant(sourceFile.languageVariant); + scanner.setOnError((message, length, arg0) => { + // For providing spelling suggestions + const start = scanner!.getTokenEnd(); + if (message.category === DiagnosticCategory.Message && lastError && start === lastError.start && length === lastError.length) { + const error = createDetachedDiagnostic(sourceFile.fileName, sourceFile.text, start, length, message, arg0); + addRelatedInfo(lastError, error); + } + else if (!lastError || start !== lastError.start) { + lastError = createFileDiagnostic(sourceFile, start, length, message, arg0); + diagnostics.add(lastError); + } + }); + scanner.setText(sourceFile.text, node.pos, node.end - node.pos); + try { + scanner.scan(); + Debug.assert(scanner.reScanSlashToken(/*reportErrors*/ true) === SyntaxKind.RegularExpressionLiteral, "Expected scanner to rescan RegularExpressionLiteral"); + return !!lastError; + } + finally { + scanner.setText(""); + scanner.setOnError(/*onError*/ undefined); + } + } + return false; + } + + function checkRegularExpressionLiteral(node: RegularExpressionLiteral) { + const nodeLinks = getNodeLinks(node); + if (!(nodeLinks.flags & NodeCheckFlags.TypeChecked)) { + nodeLinks.flags |= NodeCheckFlags.TypeChecked; + addLazyDiagnostic(() => checkGrammarRegularExpressionLiteral(node)); + } + return globalRegExpType; + } + + function checkSpreadExpression(node: SpreadElement, checkMode?: CheckMode): Type { + if (languageVersion < LanguageFeatureMinimumTarget.SpreadElements) { + checkExternalEmitHelpers(node, compilerOptions.downlevelIteration ? ExternalEmitHelpers.SpreadIncludes : ExternalEmitHelpers.SpreadArray); + } + + const arrayOrIterableType = checkExpression(node.expression, checkMode); + return checkIteratedTypeOrElementType(IterationUse.Spread, arrayOrIterableType, undefinedType, node.expression); + } + + function checkSyntheticExpression(node: SyntheticExpression): Type { + return node.isSpread ? getIndexedAccessType(node.type, numberType) : node.type; + } + + function hasDefaultValue(node: BindingElement | Expression): boolean { + return (node.kind === SyntaxKind.BindingElement && !!(node as BindingElement).initializer) || + (node.kind === SyntaxKind.BinaryExpression && (node as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken); + } + + function isSpreadIntoCallOrNew(node: ArrayLiteralExpression) { + const parent = walkUpParenthesizedExpressions(node.parent); + return isSpreadElement(parent) && isCallOrNewExpression(parent.parent); + } + + function checkArrayLiteral(node: ArrayLiteralExpression, checkMode: CheckMode | undefined, forceTuple: boolean | undefined): Type { + const elements = node.elements; + const elementCount = elements.length; + const elementTypes: Type[] = []; + const elementFlags: ElementFlags[] = []; + pushCachedContextualType(node); + const inDestructuringPattern = isAssignmentTarget(node); + const inConstContext = isConstContext(node); + const contextualType = getApparentTypeOfContextualType(node, /*contextFlags*/ undefined); + const inTupleContext = isSpreadIntoCallOrNew(node) || !!contextualType && someType(contextualType, t => isTupleLikeType(t) || isGenericMappedType(t) && !t.nameType && !!getHomomorphicTypeVariable(t.target as MappedType || t)); + + let hasOmittedExpression = false; + for (let i = 0; i < elementCount; i++) { + const e = elements[i]; + if (e.kind === SyntaxKind.SpreadElement) { + if (languageVersion < LanguageFeatureMinimumTarget.SpreadElements) { + checkExternalEmitHelpers(e, compilerOptions.downlevelIteration ? ExternalEmitHelpers.SpreadIncludes : ExternalEmitHelpers.SpreadArray); + } + const spreadType = checkExpression((e as SpreadElement).expression, checkMode, forceTuple); + if (isArrayLikeType(spreadType)) { + elementTypes.push(spreadType); + elementFlags.push(ElementFlags.Variadic); + } + else if (inDestructuringPattern) { + // Given the following situation: + // var c: {}; + // [...c] = ["", 0]; + // + // c is represented in the tree as a spread element in an array literal. + // But c really functions as a rest element, and its purpose is to provide + // a contextual type for the right hand side of the assignment. Therefore, + // instead of calling checkExpression on "...c", which will give an error + // if c is not iterable/array-like, we need to act as if we are trying to + // get the contextual element type from it. So we do something similar to + // getContextualTypeForElementExpression, which will crucially not error + // if there is no index type / iterated type. + const restElementType = getIndexTypeOfType(spreadType, numberType) || + getIteratedTypeOrElementType(IterationUse.Destructuring, spreadType, undefinedType, /*errorNode*/ undefined, /*checkAssignability*/ false) || + unknownType; + elementTypes.push(restElementType); + elementFlags.push(ElementFlags.Rest); + } + else { + elementTypes.push(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, (e as SpreadElement).expression)); + elementFlags.push(ElementFlags.Rest); + } + } + else if (exactOptionalPropertyTypes && e.kind === SyntaxKind.OmittedExpression) { + hasOmittedExpression = true; + elementTypes.push(undefinedOrMissingType); + elementFlags.push(ElementFlags.Optional); + } + else { + const type = checkExpressionForMutableLocation(e, checkMode, forceTuple); + elementTypes.push(addOptionality(type, /*isProperty*/ true, hasOmittedExpression)); + elementFlags.push(hasOmittedExpression ? ElementFlags.Optional : ElementFlags.Required); + if (inTupleContext && checkMode && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && isContextSensitive(e)) { + const inferenceContext = getInferenceContext(node); + Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context + addIntraExpressionInferenceSite(inferenceContext, e, type); + } + } + } + popContextualType(); + if (inDestructuringPattern) { + return createTupleType(elementTypes, elementFlags); + } + if (forceTuple || inConstContext || inTupleContext) { + return createArrayLiteralType(createTupleType(elementTypes, elementFlags, /*readonly*/ inConstContext && !(contextualType && someType(contextualType, isMutableArrayLikeType)))); + } + return createArrayLiteralType(createArrayType( + elementTypes.length ? + getUnionType(sameMap(elementTypes, (t, i) => elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessTypeOrUndefined(t, numberType) || anyType : t), UnionReduction.Subtype) : + strictNullChecks ? implicitNeverType : undefinedWideningType, + inConstContext, + )); + } + + function createArrayLiteralType(type: Type) { + if (!(getObjectFlags(type) & ObjectFlags.Reference)) { + return type; + } + let literalType = (type as TypeReference).literalType; + if (!literalType) { + literalType = (type as TypeReference).literalType = cloneTypeReference(type as TypeReference); + literalType.objectFlags |= ObjectFlags.ArrayLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + } + return literalType; + } + + function isNumericName(name: DeclarationName): boolean { + switch (name.kind) { + case SyntaxKind.ComputedPropertyName: + return isNumericComputedName(name); + case SyntaxKind.Identifier: + return isNumericLiteralName(name.escapedText); + case SyntaxKind.NumericLiteral: + case SyntaxKind.StringLiteral: + return isNumericLiteralName(name.text); + default: + return false; + } + } + + function isNumericComputedName(name: ComputedPropertyName): boolean { + // It seems odd to consider an expression of type Any to result in a numeric name, + // but this behavior is consistent with checkIndexedAccess + return isTypeAssignableToKind(checkComputedPropertyName(name), TypeFlags.NumberLike); + } + + function checkComputedPropertyName(node: ComputedPropertyName): Type { + const links = getNodeLinks(node.expression); + if (!links.resolvedType) { + if ( + (isTypeLiteralNode(node.parent.parent) || isClassLike(node.parent.parent) || isInterfaceDeclaration(node.parent.parent)) + && isBinaryExpression(node.expression) && node.expression.operatorToken.kind === SyntaxKind.InKeyword + && node.parent.kind !== SyntaxKind.GetAccessor && node.parent.kind !== SyntaxKind.SetAccessor + ) { + return links.resolvedType = errorType; + } + links.resolvedType = checkExpression(node.expression); + // The computed property name of a non-static class field within a loop must be stored in a block-scoped binding. + // (It needs to be bound at class evaluation time.) + if (isPropertyDeclaration(node.parent) && !hasStaticModifier(node.parent) && isClassExpression(node.parent.parent)) { + const container = getEnclosingBlockScopeContainer(node.parent.parent); + const enclosingIterationStatement = getEnclosingIterationStatement(container); + if (enclosingIterationStatement) { + // The computed field name will use a block scoped binding which can be unique for each iteration of the loop. + getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; + // The generated variable which stores the computed field name must be block-scoped. + getNodeLinks(node).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + // The generated variable which stores the class must be block-scoped. + getNodeLinks(node.parent.parent).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + } + } + // This will allow types number, string, symbol or any. It will also allow enums, the unknown + // type, and any union of these types (like string | number). + if ( + links.resolvedType.flags & TypeFlags.Nullable || + !isTypeAssignableToKind(links.resolvedType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike) && + !isTypeAssignableTo(links.resolvedType, stringNumberSymbolType) + ) { + error(node, Diagnostics.A_computed_property_name_must_be_of_type_string_number_symbol_or_any); + } + } + + return links.resolvedType; + } + + function isSymbolWithNumericName(symbol: Symbol) { + const firstDecl = symbol.declarations?.[0]; + return isNumericLiteralName(symbol.escapedName) || (firstDecl && isNamedDeclaration(firstDecl) && isNumericName(firstDecl.name)); + } + + function isSymbolWithSymbolName(symbol: Symbol) { + const firstDecl = symbol.declarations?.[0]; + return isKnownSymbol(symbol) || (firstDecl && isNamedDeclaration(firstDecl) && isComputedPropertyName(firstDecl.name) && + isTypeAssignableToKind(checkComputedPropertyName(firstDecl.name), TypeFlags.ESSymbol)); + } + + function getObjectLiteralIndexInfo(node: ObjectLiteralExpression, offset: number, properties: Symbol[], keyType: Type): IndexInfo { + const propTypes: Type[] = []; + for (let i = offset; i < properties.length; i++) { + const prop = properties[i]; + if ( + keyType === stringType && !isSymbolWithSymbolName(prop) || + keyType === numberType && isSymbolWithNumericName(prop) || + keyType === esSymbolType && isSymbolWithSymbolName(prop) + ) { + propTypes.push(getTypeOfSymbol(properties[i])); + } + } + const unionType = propTypes.length ? getUnionType(propTypes, UnionReduction.Subtype) : undefinedType; + return createIndexInfo(keyType, unionType, isConstContext(node)); + } + + function getImmediateAliasedSymbol(symbol: Symbol): Symbol | undefined { + Debug.assert((symbol.flags & SymbolFlags.Alias) !== 0, "Should only get Alias here."); + const links = getSymbolLinks(symbol); + if (!links.immediateTarget) { + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + links.immediateTarget = getTargetOfAliasDeclaration(node, /*dontRecursivelyResolve*/ true); + } + + return links.immediateTarget; + } + + function checkObjectLiteral(node: ObjectLiteralExpression, checkMode: CheckMode = CheckMode.Normal): Type { + const inDestructuringPattern = isAssignmentTarget(node); + // Grammar checking + checkGrammarObjectLiteralExpression(node, inDestructuringPattern); + + const allPropertiesTable = strictNullChecks ? createSymbolTable() : undefined; + let propertiesTable = createSymbolTable(); + let propertiesArray: Symbol[] = []; + let spread: Type = emptyObjectType; + + pushCachedContextualType(node); + const contextualType = getApparentTypeOfContextualType(node, /*contextFlags*/ undefined); + const contextualTypeHasPattern = contextualType && contextualType.pattern && + (contextualType.pattern.kind === SyntaxKind.ObjectBindingPattern || contextualType.pattern.kind === SyntaxKind.ObjectLiteralExpression); + const inConstContext = isConstContext(node); + const checkFlags = inConstContext ? CheckFlags.Readonly : 0; + const isInJavascript = isInJSFile(node) && !isInJsonFile(node); + const enumTag = isInJavascript ? getJSDocEnumTag(node) : undefined; + const isJSObjectLiteral = !contextualType && isInJavascript && !enumTag; + let objectFlags: ObjectFlags = ObjectFlags.FreshLiteral; + let patternWithComputedProperties = false; + let hasComputedStringProperty = false; + let hasComputedNumberProperty = false; + let hasComputedSymbolProperty = false; + + // Spreads may cause an early bail; ensure computed names are always checked (this is cached) + // As otherwise they may not be checked until exports for the type at this position are retrieved, + // which may never occur. + for (const elem of node.properties) { + if (elem.name && isComputedPropertyName(elem.name)) { + checkComputedPropertyName(elem.name); + } + } + + let offset = 0; + for (const memberDecl of node.properties) { + let member = getSymbolOfDeclaration(memberDecl); + const computedNameType = memberDecl.name && memberDecl.name.kind === SyntaxKind.ComputedPropertyName ? + checkComputedPropertyName(memberDecl.name) : undefined; + if ( + memberDecl.kind === SyntaxKind.PropertyAssignment || + memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment || + isObjectLiteralMethod(memberDecl) + ) { + let type = memberDecl.kind === SyntaxKind.PropertyAssignment ? checkPropertyAssignment(memberDecl, checkMode) : + // avoid resolving the left side of the ShorthandPropertyAssignment outside of the destructuring + // for error recovery purposes. For example, if a user wrote `{ a = 100 }` instead of `{ a: 100 }`. + // we don't want to say "could not find 'a'". + memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment ? checkExpressionForMutableLocation(!inDestructuringPattern && memberDecl.objectAssignmentInitializer ? memberDecl.objectAssignmentInitializer : memberDecl.name, checkMode) : + checkObjectLiteralMethod(memberDecl, checkMode); + if (isInJavascript) { + const jsDocType = getTypeForDeclarationFromJSDocComment(memberDecl); + if (jsDocType) { + checkTypeAssignableTo(type, jsDocType, memberDecl); + type = jsDocType; + } + else if (enumTag && enumTag.typeExpression) { + checkTypeAssignableTo(type, getTypeFromTypeNode(enumTag.typeExpression), memberDecl); + } + } + objectFlags |= getObjectFlags(type) & ObjectFlags.PropagatingFlags; + const nameType = computedNameType && isTypeUsableAsPropertyName(computedNameType) ? computedNameType : undefined; + const prop = nameType ? + createSymbol(SymbolFlags.Property | member.flags, getPropertyNameFromType(nameType), checkFlags | CheckFlags.Late) : + createSymbol(SymbolFlags.Property | member.flags, member.escapedName, checkFlags); + if (nameType) { + prop.links.nameType = nameType; + } + + if (inDestructuringPattern) { + // If object literal is an assignment pattern and if the assignment pattern specifies a default value + // for the property, make the property optional. + const isOptional = (memberDecl.kind === SyntaxKind.PropertyAssignment && hasDefaultValue(memberDecl.initializer)) || + (memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment && memberDecl.objectAssignmentInitializer); + if (isOptional) { + prop.flags |= SymbolFlags.Optional; + } + } + else if (contextualTypeHasPattern && !(getObjectFlags(contextualType) & ObjectFlags.ObjectLiteralPatternWithComputedProperties)) { + // If object literal is contextually typed by the implied type of a binding pattern, and if the + // binding pattern specifies a default value for the property, make the property optional. + const impliedProp = getPropertyOfType(contextualType, member.escapedName); + if (impliedProp) { + prop.flags |= impliedProp.flags & SymbolFlags.Optional; + } + else if (!getIndexInfoOfType(contextualType, stringType)) { + error(memberDecl.name, Diagnostics.Object_literal_may_only_specify_known_properties_and_0_does_not_exist_in_type_1, symbolToString(member), typeToString(contextualType)); + } + } + + prop.declarations = member.declarations; + prop.parent = member.parent; + if (member.valueDeclaration) { + prop.valueDeclaration = member.valueDeclaration; + } + + prop.links.type = type; + prop.links.target = member; + member = prop; + allPropertiesTable?.set(prop.escapedName, prop); + + if ( + contextualType && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && + (memberDecl.kind === SyntaxKind.PropertyAssignment || memberDecl.kind === SyntaxKind.MethodDeclaration) && isContextSensitive(memberDecl) + ) { + const inferenceContext = getInferenceContext(node); + Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context + const inferenceNode = memberDecl.kind === SyntaxKind.PropertyAssignment ? memberDecl.initializer : memberDecl; + addIntraExpressionInferenceSite(inferenceContext, inferenceNode, type); + } + } + else if (memberDecl.kind === SyntaxKind.SpreadAssignment) { + if (languageVersion < LanguageFeatureMinimumTarget.ObjectAssign) { + checkExternalEmitHelpers(memberDecl, ExternalEmitHelpers.Assign); + } + if (propertiesArray.length > 0) { + spread = getSpreadType(spread, createObjectLiteralType(), node.symbol, objectFlags, inConstContext); + propertiesArray = []; + propertiesTable = createSymbolTable(); + hasComputedStringProperty = false; + hasComputedNumberProperty = false; + hasComputedSymbolProperty = false; + } + const type = getReducedType(checkExpression(memberDecl.expression, checkMode & CheckMode.Inferential)); + if (isValidSpreadType(type)) { + const mergedType = tryMergeUnionOfObjectTypeAndEmptyObject(type, inConstContext); + if (allPropertiesTable) { + checkSpreadPropOverrides(mergedType, allPropertiesTable, memberDecl); + } + offset = propertiesArray.length; + if (isErrorType(spread)) { + continue; + } + spread = getSpreadType(spread, mergedType, node.symbol, objectFlags, inConstContext); + } + else { + error(memberDecl, Diagnostics.Spread_types_may_only_be_created_from_object_types); + spread = errorType; + } + continue; + } + else { + // TypeScript 1.0 spec (April 2014) + // A get accessor declaration is processed in the same manner as + // an ordinary function declaration(section 6.1) with no parameters. + // A set accessor declaration is processed in the same manner + // as an ordinary function declaration with a single parameter and a Void return type. + Debug.assert(memberDecl.kind === SyntaxKind.GetAccessor || memberDecl.kind === SyntaxKind.SetAccessor); + checkNodeDeferred(memberDecl); + } + + if (computedNameType && !(computedNameType.flags & TypeFlags.StringOrNumberLiteralOrUnique)) { + if (isTypeAssignableTo(computedNameType, stringNumberSymbolType)) { + if (isTypeAssignableTo(computedNameType, numberType)) { + hasComputedNumberProperty = true; + } + else if (isTypeAssignableTo(computedNameType, esSymbolType)) { + hasComputedSymbolProperty = true; + } + else { + hasComputedStringProperty = true; + } + if (inDestructuringPattern) { + patternWithComputedProperties = true; + } + } + } + else { + propertiesTable.set(member.escapedName, member); + } + propertiesArray.push(member); + } + popContextualType(); + + // If object literal is contextually typed by the implied type of a binding pattern, augment the result + // type with those properties for which the binding pattern specifies a default value. + // If the object literal is spread into another object literal, skip this step and let the top-level object + // literal handle it instead. Note that this might require full traversal to the root pattern's parent + // as it's the guaranteed to be the common ancestor of the pattern node and the current object node. + // It's not possible to check if the immediate parent node is a spread assignment + // since the type flows in non-obvious ways through conditional expressions, IIFEs and more. + if (contextualTypeHasPattern) { + const rootPatternParent = findAncestor(contextualType.pattern!.parent, n => + n.kind === SyntaxKind.VariableDeclaration || + n.kind === SyntaxKind.BinaryExpression || + n.kind === SyntaxKind.Parameter); + const spreadOrOutsideRootObject = findAncestor(node, n => + n === rootPatternParent || + n.kind === SyntaxKind.SpreadAssignment)!; + + if (spreadOrOutsideRootObject.kind !== SyntaxKind.SpreadAssignment) { + for (const prop of getPropertiesOfType(contextualType)) { + if (!propertiesTable.get(prop.escapedName) && !getPropertyOfType(spread, prop.escapedName)) { + if (!(prop.flags & SymbolFlags.Optional)) { + error(prop.valueDeclaration || tryCast(prop, isTransientSymbol)?.links.bindingElement, Diagnostics.Initializer_provides_no_value_for_this_binding_element_and_the_binding_element_has_no_default_value); + } + propertiesTable.set(prop.escapedName, prop); + propertiesArray.push(prop); + } + } + } + } + + if (isErrorType(spread)) { + return errorType; + } + + if (spread !== emptyObjectType) { + if (propertiesArray.length > 0) { + spread = getSpreadType(spread, createObjectLiteralType(), node.symbol, objectFlags, inConstContext); + propertiesArray = []; + propertiesTable = createSymbolTable(); + hasComputedStringProperty = false; + hasComputedNumberProperty = false; + } + // remap the raw emptyObjectType fed in at the top into a fresh empty object literal type, unique to this use site + return mapType(spread, t => t === emptyObjectType ? createObjectLiteralType() : t); + } + + return createObjectLiteralType(); + + function createObjectLiteralType() { + const indexInfos = []; + if (hasComputedStringProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, stringType)); + if (hasComputedNumberProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, numberType)); + if (hasComputedSymbolProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, esSymbolType)); + const result = createAnonymousType(node.symbol, propertiesTable, emptyArray, emptyArray, indexInfos); + result.objectFlags |= objectFlags | ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + if (isJSObjectLiteral) { + result.objectFlags |= ObjectFlags.JSLiteral; + } + if (patternWithComputedProperties) { + result.objectFlags |= ObjectFlags.ObjectLiteralPatternWithComputedProperties; + } + if (inDestructuringPattern) { + result.pattern = node; + } + return result; + } + } + + function isValidSpreadType(type: Type): boolean { + const t = removeDefinitelyFalsyTypes(mapType(type, getBaseConstraintOrType)); + return !!(t.flags & (TypeFlags.Any | TypeFlags.NonPrimitive | TypeFlags.Object | TypeFlags.InstantiableNonPrimitive) || + t.flags & TypeFlags.UnionOrIntersection && every((t as UnionOrIntersectionType).types, isValidSpreadType)); + } + + function checkJsxSelfClosingElementDeferred(node: JsxSelfClosingElement) { + checkJsxOpeningLikeElementOrOpeningFragment(node); + } + + function checkJsxSelfClosingElement(node: JsxSelfClosingElement, _checkMode: CheckMode | undefined): Type { + checkNodeDeferred(node); + return getJsxElementTypeAt(node) || anyType; + } + + function checkJsxElementDeferred(node: JsxElement) { + // Check attributes + checkJsxOpeningLikeElementOrOpeningFragment(node.openingElement); + + // Perform resolution on the closing tag so that rename/go to definition/etc work + if (isJsxIntrinsicTagName(node.closingElement.tagName)) { + getIntrinsicTagSymbol(node.closingElement); + } + else { + checkExpression(node.closingElement.tagName); + } + + checkJsxChildren(node); + } + + function checkJsxElement(node: JsxElement, _checkMode: CheckMode | undefined): Type { + checkNodeDeferred(node); + + return getJsxElementTypeAt(node) || anyType; + } + + function checkJsxFragment(node: JsxFragment): Type { + checkJsxOpeningLikeElementOrOpeningFragment(node.openingFragment); + + // by default, jsx:'react' will use jsxFactory = React.createElement and jsxFragmentFactory = React.Fragment + // if jsxFactory compiler option is provided, ensure jsxFragmentFactory compiler option or @jsxFrag pragma is provided too + const nodeSourceFile = getSourceFileOfNode(node); + if ( + getJSXTransformEnabled(compilerOptions) && (compilerOptions.jsxFactory || nodeSourceFile.pragmas.has("jsx")) + && !compilerOptions.jsxFragmentFactory && !nodeSourceFile.pragmas.has("jsxfrag") + ) { + error( + node, + compilerOptions.jsxFactory + ? Diagnostics.The_jsxFragmentFactory_compiler_option_must_be_provided_to_use_JSX_fragments_with_the_jsxFactory_compiler_option + : Diagnostics.An_jsxFrag_pragma_is_required_when_using_an_jsx_pragma_with_JSX_fragments, + ); + } + + checkJsxChildren(node); + return getJsxElementTypeAt(node) || anyType; + } + + function isHyphenatedJsxName(name: string | __String) { + return (name as string).includes("-"); + } + + /** + * Returns true iff React would emit this tag name as a string rather than an identifier or qualified name + */ + function isJsxIntrinsicTagName(tagName: Node): tagName is Identifier | JsxNamespacedName { + return isIdentifier(tagName) && isIntrinsicJsxName(tagName.escapedText) || isJsxNamespacedName(tagName); + } + + function checkJsxAttribute(node: JsxAttribute, checkMode?: CheckMode) { + return node.initializer + ? checkExpressionForMutableLocation(node.initializer, checkMode) + : trueType; // is sugar for + } + + /** + * Get attributes type of the JSX opening-like element. The result is from resolving "attributes" property of the opening-like element. + * + * @param openingLikeElement a JSX opening-like element + * @param filter a function to remove attributes that will not participate in checking whether attributes are assignable + * @return an anonymous type (similar to the one returned by checkObjectLiteral) in which its properties are attributes property. + * @remarks Because this function calls getSpreadType, it needs to use the same checks as checkObjectLiteral, + * which also calls getSpreadType. + */ + function createJsxAttributesTypeFromAttributesProperty(openingLikeElement: JsxOpeningLikeElement, checkMode: CheckMode = CheckMode.Normal) { + const attributes = openingLikeElement.attributes; + const contextualType = getContextualType(attributes, ContextFlags.None); + const allAttributesTable = strictNullChecks ? createSymbolTable() : undefined; + let attributesTable = createSymbolTable(); + let spread: Type = emptyJsxObjectType; + let hasSpreadAnyType = false; + let typeToIntersect: Type | undefined; + let explicitlySpecifyChildrenAttribute = false; + let objectFlags: ObjectFlags = ObjectFlags.JsxAttributes; + const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(openingLikeElement)); + + for (const attributeDecl of attributes.properties) { + const member = attributeDecl.symbol; + if (isJsxAttribute(attributeDecl)) { + const exprType = checkJsxAttribute(attributeDecl, checkMode); + objectFlags |= getObjectFlags(exprType) & ObjectFlags.PropagatingFlags; + + const attributeSymbol = createSymbol(SymbolFlags.Property | member.flags, member.escapedName); + attributeSymbol.declarations = member.declarations; + attributeSymbol.parent = member.parent; + if (member.valueDeclaration) { + attributeSymbol.valueDeclaration = member.valueDeclaration; + } + attributeSymbol.links.type = exprType; + attributeSymbol.links.target = member; + attributesTable.set(attributeSymbol.escapedName, attributeSymbol); + allAttributesTable?.set(attributeSymbol.escapedName, attributeSymbol); + if (getEscapedTextOfJsxAttributeName(attributeDecl.name) === jsxChildrenPropertyName) { + explicitlySpecifyChildrenAttribute = true; + } + if (contextualType) { + const prop = getPropertyOfType(contextualType, member.escapedName); + if (prop && prop.declarations && isDeprecatedSymbol(prop) && isIdentifier(attributeDecl.name)) { + addDeprecatedSuggestion(attributeDecl.name, prop.declarations, attributeDecl.name.escapedText as string); + } + } + if (contextualType && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && isContextSensitive(attributeDecl)) { + const inferenceContext = getInferenceContext(attributes); + Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context + const inferenceNode = (attributeDecl.initializer as JsxExpression).expression!; + addIntraExpressionInferenceSite(inferenceContext, inferenceNode, exprType); + } + } + else { + Debug.assert(attributeDecl.kind === SyntaxKind.JsxSpreadAttribute); + if (attributesTable.size > 0) { + spread = getSpreadType(spread, createJsxAttributesType(), attributes.symbol, objectFlags, /*readonly*/ false); + attributesTable = createSymbolTable(); + } + const exprType = getReducedType(checkExpression(attributeDecl.expression, checkMode & CheckMode.Inferential)); + if (isTypeAny(exprType)) { + hasSpreadAnyType = true; + } + if (isValidSpreadType(exprType)) { + spread = getSpreadType(spread, exprType, attributes.symbol, objectFlags, /*readonly*/ false); + if (allAttributesTable) { + checkSpreadPropOverrides(exprType, allAttributesTable, attributeDecl); + } + } + else { + error(attributeDecl.expression, Diagnostics.Spread_types_may_only_be_created_from_object_types); + typeToIntersect = typeToIntersect ? getIntersectionType([typeToIntersect, exprType]) : exprType; + } + } + } + + if (!hasSpreadAnyType) { + if (attributesTable.size > 0) { + spread = getSpreadType(spread, createJsxAttributesType(), attributes.symbol, objectFlags, /*readonly*/ false); + } + } + + // Handle children attribute + const parent = openingLikeElement.parent.kind === SyntaxKind.JsxElement ? openingLikeElement.parent as JsxElement : undefined; + // We have to check that openingElement of the parent is the one we are visiting as this may not be true for selfClosingElement + if (parent && parent.openingElement === openingLikeElement && getSemanticJsxChildren(parent.children).length > 0) { + const childrenTypes: Type[] = checkJsxChildren(parent, checkMode); + + if (!hasSpreadAnyType && jsxChildrenPropertyName && jsxChildrenPropertyName !== "") { + // Error if there is a attribute named "children" explicitly specified and children element. + // This is because children element will overwrite the value from attributes. + // Note: we will not warn "children" attribute overwritten if "children" attribute is specified in object spread. + if (explicitlySpecifyChildrenAttribute) { + error(attributes, Diagnostics._0_are_specified_twice_The_attribute_named_0_will_be_overwritten, unescapeLeadingUnderscores(jsxChildrenPropertyName)); + } + + const contextualType = getApparentTypeOfContextualType(openingLikeElement.attributes, /*contextFlags*/ undefined); + const childrenContextualType = contextualType && getTypeOfPropertyOfContextualType(contextualType, jsxChildrenPropertyName); + // If there are children in the body of JSX element, create dummy attribute "children" with the union of children types so that it will pass the attribute checking process + const childrenPropSymbol = createSymbol(SymbolFlags.Property, jsxChildrenPropertyName); + childrenPropSymbol.links.type = childrenTypes.length === 1 ? childrenTypes[0] : + childrenContextualType && someType(childrenContextualType, isTupleLikeType) ? createTupleType(childrenTypes) : + createArrayType(getUnionType(childrenTypes)); + // Fake up a property declaration for the children + childrenPropSymbol.valueDeclaration = factory.createPropertySignature(/*modifiers*/ undefined, unescapeLeadingUnderscores(jsxChildrenPropertyName), /*questionToken*/ undefined, /*type*/ undefined); + setParent(childrenPropSymbol.valueDeclaration, attributes); + childrenPropSymbol.valueDeclaration.symbol = childrenPropSymbol; + const childPropMap = createSymbolTable(); + childPropMap.set(jsxChildrenPropertyName, childrenPropSymbol); + spread = getSpreadType(spread, createAnonymousType(attributes.symbol, childPropMap, emptyArray, emptyArray, emptyArray), attributes.symbol, objectFlags, /*readonly*/ false); + } + } + + if (hasSpreadAnyType) { + return anyType; + } + if (typeToIntersect && spread !== emptyJsxObjectType) { + return getIntersectionType([typeToIntersect, spread]); + } + return typeToIntersect || (spread === emptyJsxObjectType ? createJsxAttributesType() : spread); + + /** + * Create anonymous type from given attributes symbol table. + * @param symbol a symbol of JsxAttributes containing attributes corresponding to attributesTable + * @param attributesTable a symbol table of attributes property + */ + function createJsxAttributesType() { + objectFlags |= ObjectFlags.FreshLiteral; + const result = createAnonymousType(attributes.symbol, attributesTable, emptyArray, emptyArray, emptyArray); + result.objectFlags |= objectFlags | ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + return result; + } + } + + function checkJsxChildren(node: JsxElement | JsxFragment, checkMode?: CheckMode) { + const childrenTypes: Type[] = []; + for (const child of node.children) { + // In React, JSX text that contains only whitespaces will be ignored so we don't want to type-check that + // because then type of children property will have constituent of string type. + if (child.kind === SyntaxKind.JsxText) { + if (!child.containsOnlyTriviaWhiteSpaces) { + childrenTypes.push(stringType); + } + } + else if (child.kind === SyntaxKind.JsxExpression && !child.expression) { + continue; // empty jsx expressions don't *really* count as present children + } + else { + childrenTypes.push(checkExpressionForMutableLocation(child, checkMode)); + } + } + return childrenTypes; + } + + function checkSpreadPropOverrides(type: Type, props: SymbolTable, spread: SpreadAssignment | JsxSpreadAttribute) { + for (const right of getPropertiesOfType(type)) { + if (!(right.flags & SymbolFlags.Optional)) { + const left = props.get(right.escapedName); + if (left) { + const diagnostic = error(left.valueDeclaration, Diagnostics._0_is_specified_more_than_once_so_this_usage_will_be_overwritten, unescapeLeadingUnderscores(left.escapedName)); + addRelatedInfo(diagnostic, createDiagnosticForNode(spread, Diagnostics.This_spread_always_overwrites_this_property)); + } + } + } + } + + /** + * Check attributes property of opening-like element. This function is called during chooseOverload to get call signature of a JSX opening-like element. + * (See "checkApplicableSignatureForJsxOpeningLikeElement" for how the function is used) + * @param node a JSXAttributes to be resolved of its type + */ + function checkJsxAttributes(node: JsxAttributes, checkMode: CheckMode | undefined) { + return createJsxAttributesTypeFromAttributesProperty(node.parent, checkMode); + } + + function getJsxType(name: __String, location: Node | undefined) { + const namespace = getJsxNamespaceAt(location); + const exports = namespace && getExportsOfSymbol(namespace); + const typeSymbol = exports && getSymbol(exports, name, SymbolFlags.Type); + return typeSymbol ? getDeclaredTypeOfSymbol(typeSymbol) : errorType; + } + + /** + * Looks up an intrinsic tag name and returns a symbol that either points to an intrinsic + * property (in which case nodeLinks.jsxFlags will be IntrinsicNamedElement) or an intrinsic + * string index signature (in which case nodeLinks.jsxFlags will be IntrinsicIndexedElement). + * May also return unknownSymbol if both of these lookups fail. + */ + function getIntrinsicTagSymbol(node: JsxOpeningLikeElement | JsxClosingElement): Symbol { + const links = getNodeLinks(node); + if (!links.resolvedSymbol) { + const intrinsicElementsType = getJsxType(JsxNames.IntrinsicElements, node); + if (!isErrorType(intrinsicElementsType)) { + // Property case + if (!isIdentifier(node.tagName) && !isJsxNamespacedName(node.tagName)) return Debug.fail(); + const propName = isJsxNamespacedName(node.tagName) ? getEscapedTextOfJsxNamespacedName(node.tagName) : node.tagName.escapedText; + const intrinsicProp = getPropertyOfType(intrinsicElementsType, propName); + if (intrinsicProp) { + links.jsxFlags |= JsxFlags.IntrinsicNamedElement; + return links.resolvedSymbol = intrinsicProp; + } + + // Intrinsic string indexer case + const indexSymbol = getApplicableIndexSymbol(intrinsicElementsType, getStringLiteralType(unescapeLeadingUnderscores(propName))); + if (indexSymbol) { + links.jsxFlags |= JsxFlags.IntrinsicIndexedElement; + return links.resolvedSymbol = indexSymbol; + } + + if (getTypeOfPropertyOrIndexSignatureOfType(intrinsicElementsType, propName)) { + links.jsxFlags |= JsxFlags.IntrinsicIndexedElement; + return links.resolvedSymbol = intrinsicElementsType.symbol; + } + + // Wasn't found + error(node, Diagnostics.Property_0_does_not_exist_on_type_1, intrinsicTagNameToString(node.tagName), "JSX." + JsxNames.IntrinsicElements); + return links.resolvedSymbol = unknownSymbol; + } + else { + if (noImplicitAny) { + error(node, Diagnostics.JSX_element_implicitly_has_type_any_because_no_interface_JSX_0_exists, unescapeLeadingUnderscores(JsxNames.IntrinsicElements)); + } + return links.resolvedSymbol = unknownSymbol; + } + } + return links.resolvedSymbol; + } + + function getJsxNamespaceContainerForImplicitImport(location: Node | undefined): Symbol | undefined { + const file = location && getSourceFileOfNode(location); + const links = file && getNodeLinks(file); + if (links && links.jsxImplicitImportContainer === false) { + return undefined; + } + if (links && links.jsxImplicitImportContainer) { + return links.jsxImplicitImportContainer; + } + const runtimeImportSpecifier = getJSXRuntimeImport(getJSXImplicitImportBase(compilerOptions, file), compilerOptions); + if (!runtimeImportSpecifier) { + return undefined; + } + const isClassic = getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic; + const errorMessage = isClassic + ? Diagnostics.Cannot_find_module_0_Did_you_mean_to_set_the_moduleResolution_option_to_nodenext_or_to_add_aliases_to_the_paths_option + : Diagnostics.Cannot_find_module_0_or_its_corresponding_type_declarations; + const specifier = getJSXRuntimeImportSpecifier(file, runtimeImportSpecifier); + const mod = resolveExternalModule(specifier || location!, runtimeImportSpecifier, errorMessage, location!); + const result = mod && mod !== unknownSymbol ? getMergedSymbol(resolveSymbol(mod)) : undefined; + if (links) { + links.jsxImplicitImportContainer = result || false; + } + return result; + } + + function getJsxNamespaceAt(location: Node | undefined): Symbol { + const links = location && getNodeLinks(location); + if (links && links.jsxNamespace) { + return links.jsxNamespace; + } + if (!links || links.jsxNamespace !== false) { + let resolvedNamespace = getJsxNamespaceContainerForImplicitImport(location); + + if (!resolvedNamespace || resolvedNamespace === unknownSymbol) { + const namespaceName = getJsxNamespace(location); + resolvedNamespace = resolveName(location, namespaceName, SymbolFlags.Namespace, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + } + + if (resolvedNamespace) { + const candidate = resolveSymbol(getSymbol(getExportsOfSymbol(resolveSymbol(resolvedNamespace)), JsxNames.JSX, SymbolFlags.Namespace)); + if (candidate && candidate !== unknownSymbol) { + if (links) { + links.jsxNamespace = candidate; + } + return candidate; + } + } + if (links) { + links.jsxNamespace = false; + } + } + // JSX global fallback + const s = resolveSymbol(getGlobalSymbol(JsxNames.JSX, SymbolFlags.Namespace, /*diagnostic*/ undefined)); + if (s === unknownSymbol) { + return undefined!; // TODO: GH#18217 + } + return s!; // TODO: GH#18217 + } + + /** + * Look into JSX namespace and then look for container with matching name as nameOfAttribPropContainer. + * Get a single property from that container if existed. Report an error if there are more than one property. + * + * @param nameOfAttribPropContainer a string of value JsxNames.ElementAttributesPropertyNameContainer or JsxNames.ElementChildrenAttributeNameContainer + * if other string is given or the container doesn't exist, return undefined. + */ + function getNameFromJsxElementAttributesContainer(nameOfAttribPropContainer: __String, jsxNamespace: Symbol): __String | undefined { + // JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute [symbol] + const jsxElementAttribPropInterfaceSym = jsxNamespace && getSymbol(jsxNamespace.exports!, nameOfAttribPropContainer, SymbolFlags.Type); + // JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute [type] + const jsxElementAttribPropInterfaceType = jsxElementAttribPropInterfaceSym && getDeclaredTypeOfSymbol(jsxElementAttribPropInterfaceSym); + // The properties of JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute + const propertiesOfJsxElementAttribPropInterface = jsxElementAttribPropInterfaceType && getPropertiesOfType(jsxElementAttribPropInterfaceType); + if (propertiesOfJsxElementAttribPropInterface) { + // Element Attributes has zero properties, so the element attributes type will be the class instance type + if (propertiesOfJsxElementAttribPropInterface.length === 0) { + return "" as __String; + } + // Element Attributes has one property, so the element attributes type will be the type of the corresponding + // property of the class instance type + else if (propertiesOfJsxElementAttribPropInterface.length === 1) { + return propertiesOfJsxElementAttribPropInterface[0].escapedName; + } + else if (propertiesOfJsxElementAttribPropInterface.length > 1 && jsxElementAttribPropInterfaceSym.declarations) { + // More than one property on ElementAttributesProperty is an error + error(jsxElementAttribPropInterfaceSym.declarations[0], Diagnostics.The_global_type_JSX_0_may_not_have_more_than_one_property, unescapeLeadingUnderscores(nameOfAttribPropContainer)); + } + } + return undefined; + } + + function getJsxLibraryManagedAttributes(jsxNamespace: Symbol) { + // JSX.LibraryManagedAttributes [symbol] + return jsxNamespace && getSymbol(jsxNamespace.exports!, JsxNames.LibraryManagedAttributes, SymbolFlags.Type); + } + + function getJsxElementTypeSymbol(jsxNamespace: Symbol) { + // JSX.ElementType [symbol] + return jsxNamespace && getSymbol(jsxNamespace.exports!, JsxNames.ElementType, SymbolFlags.Type); + } + + /// e.g. "props" for React.d.ts, + /// or 'undefined' if ElementAttributesProperty doesn't exist (which means all + /// non-intrinsic elements' attributes type is 'any'), + /// or '' if it has 0 properties (which means every + /// non-intrinsic elements' attributes type is the element instance type) + function getJsxElementPropertiesName(jsxNamespace: Symbol) { + return getNameFromJsxElementAttributesContainer(JsxNames.ElementAttributesPropertyNameContainer, jsxNamespace); + } + + function getJsxElementChildrenPropertyName(jsxNamespace: Symbol): __String | undefined { + return getNameFromJsxElementAttributesContainer(JsxNames.ElementChildrenAttributeNameContainer, jsxNamespace); + } + + function getUninstantiatedJsxSignaturesOfType(elementType: Type, caller: JsxOpeningLikeElement): readonly Signature[] { + if (elementType.flags & TypeFlags.String) { + return [anySignature]; + } + else if (elementType.flags & TypeFlags.StringLiteral) { + const intrinsicType = getIntrinsicAttributesTypeFromStringLiteralType(elementType as StringLiteralType, caller); + if (!intrinsicType) { + error(caller, Diagnostics.Property_0_does_not_exist_on_type_1, (elementType as StringLiteralType).value, "JSX." + JsxNames.IntrinsicElements); + return emptyArray; + } + else { + const fakeSignature = createSignatureForJSXIntrinsic(caller, intrinsicType); + return [fakeSignature]; + } + } + const apparentElemType = getApparentType(elementType); + // Resolve the signatures, preferring constructor + let signatures = getSignaturesOfType(apparentElemType, SignatureKind.Construct); + if (signatures.length === 0) { + // No construct signatures, try call signatures + signatures = getSignaturesOfType(apparentElemType, SignatureKind.Call); + } + if (signatures.length === 0 && apparentElemType.flags & TypeFlags.Union) { + // If each member has some combination of new/call signatures; make a union signature list for those + signatures = getUnionSignatures(map((apparentElemType as UnionType).types, t => getUninstantiatedJsxSignaturesOfType(t, caller))); + } + return signatures; + } + + function getIntrinsicAttributesTypeFromStringLiteralType(type: StringLiteralType, location: Node): Type | undefined { + // If the elemType is a stringLiteral type, we can then provide a check to make sure that the string literal type is one of the Jsx intrinsic element type + // For example: + // var CustomTag: "h1" = "h1"; + // Hello World + const intrinsicElementsType = getJsxType(JsxNames.IntrinsicElements, location); + if (!isErrorType(intrinsicElementsType)) { + const stringLiteralTypeName = type.value; + const intrinsicProp = getPropertyOfType(intrinsicElementsType, escapeLeadingUnderscores(stringLiteralTypeName)); + if (intrinsicProp) { + return getTypeOfSymbol(intrinsicProp); + } + const indexSignatureType = getIndexTypeOfType(intrinsicElementsType, stringType); + if (indexSignatureType) { + return indexSignatureType; + } + return undefined; + } + // If we need to report an error, we already done so here. So just return any to prevent any more error downstream + return anyType; + } + + function checkJsxReturnAssignableToAppropriateBound(refKind: JsxReferenceKind, elemInstanceType: Type, openingLikeElement: JsxOpeningLikeElement) { + if (refKind === JsxReferenceKind.Function) { + const sfcReturnConstraint = getJsxStatelessElementTypeAt(openingLikeElement); + if (sfcReturnConstraint) { + checkTypeRelatedTo(elemInstanceType, sfcReturnConstraint, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_return_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); + } + } + else if (refKind === JsxReferenceKind.Component) { + const classConstraint = getJsxElementClassTypeAt(openingLikeElement); + if (classConstraint) { + // Issue an error if this return type isn't assignable to JSX.ElementClass, failing that + checkTypeRelatedTo(elemInstanceType, classConstraint, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_instance_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); + } + } + else { // Mixed + const sfcReturnConstraint = getJsxStatelessElementTypeAt(openingLikeElement); + const classConstraint = getJsxElementClassTypeAt(openingLikeElement); + if (!sfcReturnConstraint || !classConstraint) { + return; + } + const combined = getUnionType([sfcReturnConstraint, classConstraint]); + checkTypeRelatedTo(elemInstanceType, combined, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_element_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); + } + + function generateInitialErrorChain(): DiagnosticMessageChain { + const componentName = getTextOfNode(openingLikeElement.tagName); + return chainDiagnosticMessages(/*details*/ undefined, Diagnostics._0_cannot_be_used_as_a_JSX_component, componentName); + } + } + + /** + * Get attributes type of the given intrinsic opening-like Jsx element by resolving the tag name. + * The function is intended to be called from a function which has checked that the opening element is an intrinsic element. + * @param node an intrinsic JSX opening-like element + */ + function getIntrinsicAttributesTypeFromJsxOpeningLikeElement(node: JsxOpeningLikeElement): Type { + Debug.assert(isJsxIntrinsicTagName(node.tagName)); + const links = getNodeLinks(node); + if (!links.resolvedJsxElementAttributesType) { + const symbol = getIntrinsicTagSymbol(node); + if (links.jsxFlags & JsxFlags.IntrinsicNamedElement) { + return links.resolvedJsxElementAttributesType = getTypeOfSymbol(symbol) || errorType; + } + else if (links.jsxFlags & JsxFlags.IntrinsicIndexedElement) { + const propName = isJsxNamespacedName(node.tagName) ? getEscapedTextOfJsxNamespacedName(node.tagName) : node.tagName.escapedText; + return links.resolvedJsxElementAttributesType = getApplicableIndexInfoForName(getJsxType(JsxNames.IntrinsicElements, node), propName)?.type || errorType; + } + else { + return links.resolvedJsxElementAttributesType = errorType; + } + } + return links.resolvedJsxElementAttributesType; + } + + function getJsxElementClassTypeAt(location: Node): Type | undefined { + const type = getJsxType(JsxNames.ElementClass, location); + if (isErrorType(type)) return undefined; + return type; + } + + function getJsxElementTypeAt(location: Node): Type { + return getJsxType(JsxNames.Element, location); + } + + function getJsxStatelessElementTypeAt(location: Node): Type | undefined { + const jsxElementType = getJsxElementTypeAt(location); + if (jsxElementType) { + return getUnionType([jsxElementType, nullType]); + } + } + + function getJsxElementTypeTypeAt(location: Node): Type | undefined { + const ns = getJsxNamespaceAt(location); + if (!ns) return undefined; + const sym = getJsxElementTypeSymbol(ns); + if (!sym) return undefined; + const type = instantiateAliasOrInterfaceWithDefaults(sym, isInJSFile(location)); + if (!type || isErrorType(type)) return undefined; + return type; + } + + function instantiateAliasOrInterfaceWithDefaults(managedSym: Symbol, inJs: boolean, ...typeArguments: Type[]) { + const declaredManagedType = getDeclaredTypeOfSymbol(managedSym); // fetches interface type, or initializes symbol links type parmaeters + if (managedSym.flags & SymbolFlags.TypeAlias) { + const params = getSymbolLinks(managedSym).typeParameters; + if (length(params) >= typeArguments.length) { + const args = fillMissingTypeArguments(typeArguments, params, typeArguments.length, inJs); + return length(args) === 0 ? declaredManagedType : getTypeAliasInstantiation(managedSym, args); + } + } + if (length((declaredManagedType as GenericType).typeParameters) >= typeArguments.length) { + const args = fillMissingTypeArguments(typeArguments, (declaredManagedType as GenericType).typeParameters, typeArguments.length, inJs); + return createTypeReference(declaredManagedType as GenericType, args); + } + return undefined; + } + + /** + * Returns all the properties of the Jsx.IntrinsicElements interface + */ + function getJsxIntrinsicTagNamesAt(location: Node): Symbol[] { + const intrinsics = getJsxType(JsxNames.IntrinsicElements, location); + return intrinsics ? getPropertiesOfType(intrinsics) : emptyArray; + } + + function checkJsxPreconditions(errorNode: Node) { + // Preconditions for using JSX + if ((compilerOptions.jsx || JsxEmit.None) === JsxEmit.None) { + error(errorNode, Diagnostics.Cannot_use_JSX_unless_the_jsx_flag_is_provided); + } + + if (getJsxElementTypeAt(errorNode) === undefined) { + if (noImplicitAny) { + error(errorNode, Diagnostics.JSX_element_implicitly_has_type_any_because_the_global_type_JSX_Element_does_not_exist); + } + } + } + + function checkJsxOpeningLikeElementOrOpeningFragment(node: JsxOpeningLikeElement | JsxOpeningFragment) { + const isNodeOpeningLikeElement = isJsxOpeningLikeElement(node); + + if (isNodeOpeningLikeElement) { + checkGrammarJsxElement(node); + } + + checkJsxPreconditions(node); + + markLinkedReferences(node, ReferenceHint.Jsx); + + if (isNodeOpeningLikeElement) { + const jsxOpeningLikeNode = node; + const sig = getResolvedSignature(jsxOpeningLikeNode); + checkDeprecatedSignature(sig, node); + + const elementTypeConstraint = getJsxElementTypeTypeAt(jsxOpeningLikeNode); + if (elementTypeConstraint !== undefined) { + const tagName = jsxOpeningLikeNode.tagName; + const tagType = isJsxIntrinsicTagName(tagName) + ? getStringLiteralType(intrinsicTagNameToString(tagName)) + : checkExpression(tagName); + checkTypeRelatedTo(tagType, elementTypeConstraint, assignableRelation, tagName, Diagnostics.Its_type_0_is_not_a_valid_JSX_element_type, () => { + const componentName = getTextOfNode(tagName); + return chainDiagnosticMessages(/*details*/ undefined, Diagnostics._0_cannot_be_used_as_a_JSX_component, componentName); + }); + } + else { + checkJsxReturnAssignableToAppropriateBound(getJsxReferenceKind(jsxOpeningLikeNode), getReturnTypeOfSignature(sig), jsxOpeningLikeNode); + } + } + } + + /** + * Check if a property with the given name is known anywhere in the given type. In an object type, a property + * is considered known if + * 1. the object type is empty and the check is for assignability, or + * 2. if the object type has index signatures, or + * 3. if the property is actually declared in the object type + * (this means that 'toString', for example, is not usually a known property). + * 4. In a union or intersection type, + * a property is considered known if it is known in any constituent type. + * @param targetType a type to search a given name in + * @param name a property name to search + * @param isComparingJsxAttributes a boolean flag indicating whether we are searching in JsxAttributesType + */ + function isKnownProperty(targetType: Type, name: __String, isComparingJsxAttributes: boolean): boolean { + if (targetType.flags & TypeFlags.Object) { + // For backwards compatibility a symbol-named property is satisfied by a string index signature. This + // is incorrect and inconsistent with element access expressions, where it is an error, so eventually + // we should remove this exception. + if ( + getPropertyOfObjectType(targetType, name) || + getApplicableIndexInfoForName(targetType, name) || + isLateBoundName(name) && getIndexInfoOfType(targetType, stringType) || + isComparingJsxAttributes && isHyphenatedJsxName(name) + ) { + // For JSXAttributes, if the attribute has a hyphenated name, consider that the attribute to be known. + return true; + } + } + if (targetType.flags & TypeFlags.Substitution) { + return isKnownProperty((targetType as SubstitutionType).baseType, name, isComparingJsxAttributes); + } + if (targetType.flags & TypeFlags.UnionOrIntersection && isExcessPropertyCheckTarget(targetType)) { + for (const t of (targetType as UnionOrIntersectionType).types) { + if (isKnownProperty(t, name, isComparingJsxAttributes)) { + return true; + } + } + } + return false; + } + + function isExcessPropertyCheckTarget(type: Type): boolean { + return !!(type.flags & TypeFlags.Object && !(getObjectFlags(type) & ObjectFlags.ObjectLiteralPatternWithComputedProperties) || + type.flags & TypeFlags.NonPrimitive || + type.flags & TypeFlags.Substitution && isExcessPropertyCheckTarget((type as SubstitutionType).baseType) || + type.flags & TypeFlags.Union && some((type as UnionType).types, isExcessPropertyCheckTarget) || + type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, isExcessPropertyCheckTarget)); + } + + function checkJsxExpression(node: JsxExpression, checkMode?: CheckMode) { + checkGrammarJsxExpression(node); + if (node.expression) { + const type = checkExpression(node.expression, checkMode); + if (node.dotDotDotToken && type !== anyType && !isArrayType(type)) { + error(node, Diagnostics.JSX_spread_child_must_be_an_array_type); + } + return type; + } + else { + return errorType; + } + } + + function getDeclarationNodeFlagsFromSymbol(s: Symbol): NodeFlags { + return s.valueDeclaration ? getCombinedNodeFlagsCached(s.valueDeclaration) : 0; + } + + /** + * Return whether this symbol is a member of a prototype somewhere + * Note that this is not tracked well within the compiler, so the answer may be incorrect. + */ + function isPrototypeProperty(symbol: Symbol) { + if (symbol.flags & SymbolFlags.Method || getCheckFlags(symbol) & CheckFlags.SyntheticMethod) { + return true; + } + if (isInJSFile(symbol.valueDeclaration)) { + const parent = symbol.valueDeclaration!.parent; + return parent && isBinaryExpression(parent) && + getAssignmentDeclarationKind(parent) === AssignmentDeclarationKind.PrototypeProperty; + } + } + + /** + * Check whether the requested property access is valid. + * Returns true if node is a valid property access, and false otherwise. + * @param node The node to be checked. + * @param isSuper True if the access is from `super.`. + * @param type The type of the object whose property is being accessed. (Not the type of the property.) + * @param prop The symbol for the property being accessed. + */ + function checkPropertyAccessibility( + node: PropertyAccessExpression | QualifiedName | PropertyAccessExpression | VariableDeclaration | ParameterDeclaration | ImportTypeNode | PropertyAssignment | ShorthandPropertyAssignment | BindingElement, + isSuper: boolean, + writing: boolean, + type: Type, + prop: Symbol, + reportError = true, + ): boolean { + const errorNode = !reportError ? undefined : + node.kind === SyntaxKind.QualifiedName ? node.right : + node.kind === SyntaxKind.ImportType ? node : + node.kind === SyntaxKind.BindingElement && node.propertyName ? node.propertyName : node.name; + + return checkPropertyAccessibilityAtLocation(node, isSuper, writing, type, prop, errorNode); + } + + /** + * Check whether the requested property can be accessed at the requested location. + * Returns true if node is a valid property access, and false otherwise. + * @param location The location node where we want to check if the property is accessible. + * @param isSuper True if the access is from `super.`. + * @param writing True if this is a write property access, false if it is a read property access. + * @param containingType The type of the object whose property is being accessed. (Not the type of the property.) + * @param prop The symbol for the property being accessed. + * @param errorNode The node where we should report an invalid property access error, or undefined if we should not report errors. + */ + function checkPropertyAccessibilityAtLocation(location: Node, isSuper: boolean, writing: boolean, containingType: Type, prop: Symbol, errorNode?: Node): boolean { + const flags = getDeclarationModifierFlagsFromSymbol(prop, writing); + + if (isSuper) { + // TS 1.0 spec (April 2014): 4.8.2 + // - In a constructor, instance member function, instance member accessor, or + // instance member variable initializer where this references a derived class instance, + // a super property access is permitted and must specify a public instance member function of the base class. + // - In a static member function or static member accessor + // where this references the constructor function object of a derived class, + // a super property access is permitted and must specify a public static member function of the base class. + if (languageVersion < ScriptTarget.ES2015) { + if (symbolHasNonMethodDeclaration(prop)) { + if (errorNode) { + error(errorNode, Diagnostics.Only_public_and_protected_methods_of_the_base_class_are_accessible_via_the_super_keyword); + } + return false; + } + } + if (flags & ModifierFlags.Abstract) { + // A method cannot be accessed in a super property access if the method is abstract. + // This error could mask a private property access error. But, a member + // cannot simultaneously be private and abstract, so this will trigger an + // additional error elsewhere. + if (errorNode) { + error(errorNode, Diagnostics.Abstract_method_0_in_class_1_cannot_be_accessed_via_super_expression, symbolToString(prop), typeToString(getDeclaringClass(prop)!)); + } + return false; + } + // A class field cannot be accessed via super.* from a derived class. + // This is true for both [[Set]] (old) and [[Define]] (ES spec) semantics. + if (!(flags & ModifierFlags.Static) && prop.declarations?.some(isClassInstanceProperty)) { + if (errorNode) { + error(errorNode, Diagnostics.Class_field_0_defined_by_the_parent_class_is_not_accessible_in_the_child_class_via_super, symbolToString(prop)); + } + return false; + } + } + + // Referencing abstract properties within their own constructors is not allowed + if ( + (flags & ModifierFlags.Abstract) && symbolHasNonMethodDeclaration(prop) && + (isThisProperty(location) || isThisInitializedObjectBindingExpression(location) || isObjectBindingPattern(location.parent) && isThisInitializedDeclaration(location.parent.parent)) + ) { + const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(getParentOfSymbol(prop)!); + if (declaringClassDeclaration && isNodeUsedDuringClassInitialization(location)) { + if (errorNode) { + error(errorNode, Diagnostics.Abstract_property_0_in_class_1_cannot_be_accessed_in_the_constructor, symbolToString(prop), getTextOfIdentifierOrLiteral(declaringClassDeclaration.name!)); + } + return false; + } + } + + // Public properties are otherwise accessible. + if (!(flags & ModifierFlags.NonPublicAccessibilityModifier)) { + return true; + } + + // Property is known to be private or protected at this point + + // Private property is accessible if the property is within the declaring class + if (flags & ModifierFlags.Private) { + const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(getParentOfSymbol(prop)!)!; + if (!isNodeWithinClass(location, declaringClassDeclaration)) { + if (errorNode) { + error(errorNode, Diagnostics.Property_0_is_private_and_only_accessible_within_class_1, symbolToString(prop), typeToString(getDeclaringClass(prop)!)); + } + return false; + } + return true; + } + + // Property is known to be protected at this point + + // All protected properties of a supertype are accessible in a super access + if (isSuper) { + return true; + } + + // Find the first enclosing class that has the declaring classes of the protected constituents + // of the property as base classes + let enclosingClass = forEachEnclosingClass(location, enclosingDeclaration => { + const enclosingClass = getDeclaredTypeOfSymbol(getSymbolOfDeclaration(enclosingDeclaration)) as InterfaceType; + return isClassDerivedFromDeclaringClasses(enclosingClass, prop, writing); + }); + // A protected property is accessible if the property is within the declaring class or classes derived from it + if (!enclosingClass) { + // allow PropertyAccessibility if context is in function with this parameter + // static member access is disallowed + enclosingClass = getEnclosingClassFromThisParameter(location); + enclosingClass = enclosingClass && isClassDerivedFromDeclaringClasses(enclosingClass, prop, writing); + if (flags & ModifierFlags.Static || !enclosingClass) { + if (errorNode) { + error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_within_class_1_and_its_subclasses, symbolToString(prop), typeToString(getDeclaringClass(prop) || containingType)); + } + return false; + } + } + // No further restrictions for static properties + if (flags & ModifierFlags.Static) { + return true; + } + if (containingType.flags & TypeFlags.TypeParameter) { + // get the original type -- represented as the type constraint of the 'this' type + containingType = (containingType as TypeParameter).isThisType ? getConstraintOfTypeParameter(containingType as TypeParameter)! : getBaseConstraintOfType(containingType as TypeParameter)!; // TODO: GH#18217 Use a different variable that's allowed to be undefined + } + if (!containingType || !hasBaseType(containingType, enclosingClass)) { + if (errorNode) { + error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_through_an_instance_of_class_1_This_is_an_instance_of_class_2, symbolToString(prop), typeToString(enclosingClass), typeToString(containingType)); + } + return false; + } + return true; + } + + function getEnclosingClassFromThisParameter(node: Node): InterfaceType | undefined { + const thisParameter = getThisParameterFromNodeContext(node); + let thisType = thisParameter?.type && getTypeFromTypeNode(thisParameter.type); + if (thisType && thisType.flags & TypeFlags.TypeParameter) { + thisType = getConstraintOfTypeParameter(thisType as TypeParameter); + } + if (thisType && getObjectFlags(thisType) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference)) { + return getTargetType(thisType) as InterfaceType; + } + return undefined; + } + + function getThisParameterFromNodeContext(node: Node) { + const thisContainer = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + return thisContainer && isFunctionLike(thisContainer) ? getThisParameter(thisContainer) : undefined; + } + + function symbolHasNonMethodDeclaration(symbol: Symbol) { + return !!forEachProperty(symbol, prop => !(prop.flags & SymbolFlags.Method)); + } + + function checkNonNullExpression(node: Expression | QualifiedName) { + return checkNonNullType(checkExpression(node), node); + } + + function isNullableType(type: Type) { + return hasTypeFacts(type, TypeFacts.IsUndefinedOrNull); + } + + function getNonNullableTypeIfNeeded(type: Type) { + return isNullableType(type) ? getNonNullableType(type) : type; + } + + function reportObjectPossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) { + const nodeText = isEntityNameExpression(node) ? entityNameToString(node) : undefined; + if (node.kind === SyntaxKind.NullKeyword) { + error(node, Diagnostics.The_value_0_cannot_be_used_here, "null"); + return; + } + if (nodeText !== undefined && nodeText.length < 100) { + if (isIdentifier(node) && nodeText === "undefined") { + error(node, Diagnostics.The_value_0_cannot_be_used_here, "undefined"); + return; + } + error( + node, + facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? + Diagnostics._0_is_possibly_null_or_undefined : + Diagnostics._0_is_possibly_undefined : + Diagnostics._0_is_possibly_null, + nodeText, + ); + } + else { + error( + node, + facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? + Diagnostics.Object_is_possibly_null_or_undefined : + Diagnostics.Object_is_possibly_undefined : + Diagnostics.Object_is_possibly_null, + ); + } + } + + function reportCannotInvokePossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) { + error( + node, + facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? + Diagnostics.Cannot_invoke_an_object_which_is_possibly_null_or_undefined : + Diagnostics.Cannot_invoke_an_object_which_is_possibly_undefined : + Diagnostics.Cannot_invoke_an_object_which_is_possibly_null, + ); + } + + function checkNonNullTypeWithReporter( + type: Type, + node: Node, + reportError: (node: Node, facts: TypeFacts) => void, + ): Type { + if (strictNullChecks && type.flags & TypeFlags.Unknown) { + if (isEntityNameExpression(node)) { + const nodeText = entityNameToString(node); + if (nodeText.length < 100) { + error(node, Diagnostics._0_is_of_type_unknown, nodeText); + return errorType; + } + } + error(node, Diagnostics.Object_is_of_type_unknown); + return errorType; + } + const facts = getTypeFacts(type, TypeFacts.IsUndefinedOrNull); + if (facts & TypeFacts.IsUndefinedOrNull) { + reportError(node, facts); + const t = getNonNullableType(type); + return t.flags & (TypeFlags.Nullable | TypeFlags.Never) ? errorType : t; + } + return type; + } + + function checkNonNullType(type: Type, node: Node) { + return checkNonNullTypeWithReporter(type, node, reportObjectPossiblyNullOrUndefinedError); + } + + function checkNonNullNonVoidType(type: Type, node: Node): Type { + const nonNullType = checkNonNullType(type, node); + if (nonNullType.flags & TypeFlags.Void) { + if (isEntityNameExpression(node)) { + const nodeText = entityNameToString(node); + if (isIdentifier(node) && nodeText === "undefined") { + error(node, Diagnostics.The_value_0_cannot_be_used_here, nodeText); + return nonNullType; + } + if (nodeText.length < 100) { + error(node, Diagnostics._0_is_possibly_undefined, nodeText); + return nonNullType; + } + } + error(node, Diagnostics.Object_is_possibly_undefined); + } + return nonNullType; + } + + function checkPropertyAccessExpression(node: PropertyAccessExpression, checkMode: CheckMode | undefined, writeOnly?: boolean) { + return node.flags & NodeFlags.OptionalChain ? checkPropertyAccessChain(node as PropertyAccessChain, checkMode) : + checkPropertyAccessExpressionOrQualifiedName(node, node.expression, checkNonNullExpression(node.expression), node.name, checkMode, writeOnly); + } + + function checkPropertyAccessChain(node: PropertyAccessChain, checkMode: CheckMode | undefined) { + const leftType = checkExpression(node.expression); + const nonOptionalType = getOptionalExpressionType(leftType, node.expression); + return propagateOptionalTypeMarker(checkPropertyAccessExpressionOrQualifiedName(node, node.expression, checkNonNullType(nonOptionalType, node.expression), node.name, checkMode), node, nonOptionalType !== leftType); + } + + function checkQualifiedName(node: QualifiedName, checkMode: CheckMode | undefined) { + const leftType = isPartOfTypeQuery(node) && isThisIdentifier(node.left) ? checkNonNullType(checkThisExpression(node.left), node.left) : checkNonNullExpression(node.left); + return checkPropertyAccessExpressionOrQualifiedName(node, node.left, leftType, node.right, checkMode); + } + + function isMethodAccessForCall(node: Node) { + while (node.parent.kind === SyntaxKind.ParenthesizedExpression) { + node = node.parent; + } + return isCallOrNewExpression(node.parent) && node.parent.expression === node; + } + + // Lookup the private identifier lexically. + function lookupSymbolForPrivateIdentifierDeclaration(propName: __String, location: Node): Symbol | undefined { + for (let containingClass = getContainingClassExcludingClassDecorators(location); !!containingClass; containingClass = getContainingClass(containingClass)) { + const { symbol } = containingClass; + const name = getSymbolNameForPrivateIdentifier(symbol, propName); + const prop = (symbol.members && symbol.members.get(name)) || (symbol.exports && symbol.exports.get(name)); + if (prop) { + return prop; + } + } + } + + function checkGrammarPrivateIdentifierExpression(privId: PrivateIdentifier): boolean { + if (!getContainingClass(privId)) { + return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + + if (!isForInStatement(privId.parent)) { + if (!isExpressionNode(privId)) { + return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_only_allowed_in_class_bodies_and_may_only_be_used_as_part_of_a_class_member_declaration_property_access_or_on_the_left_hand_side_of_an_in_expression); + } + + const isInOperation = isBinaryExpression(privId.parent) && privId.parent.operatorToken.kind === SyntaxKind.InKeyword; + if (!getSymbolForPrivateIdentifierExpression(privId) && !isInOperation) { + return grammarErrorOnNode(privId, Diagnostics.Cannot_find_name_0, idText(privId)); + } + } + + return false; + } + + function checkPrivateIdentifierExpression(privId: PrivateIdentifier): Type { + checkGrammarPrivateIdentifierExpression(privId); + const symbol = getSymbolForPrivateIdentifierExpression(privId); + if (symbol) { + markPropertyAsReferenced(symbol, /*nodeForCheckWriteOnly*/ undefined, /*isSelfTypeAccess*/ false); + } + return anyType; + } + + function getSymbolForPrivateIdentifierExpression(privId: PrivateIdentifier): Symbol | undefined { + if (!isExpressionNode(privId)) { + return undefined; + } + + const links = getNodeLinks(privId); + if (links.resolvedSymbol === undefined) { + links.resolvedSymbol = lookupSymbolForPrivateIdentifierDeclaration(privId.escapedText, privId); + } + return links.resolvedSymbol; + } + + function getPrivateIdentifierPropertyOfType(leftType: Type, lexicallyScopedIdentifier: Symbol): Symbol | undefined { + return getPropertyOfType(leftType, lexicallyScopedIdentifier.escapedName); + } + + function checkPrivateIdentifierPropertyAccess(leftType: Type, right: PrivateIdentifier, lexicallyScopedIdentifier: Symbol | undefined): boolean { + // Either the identifier could not be looked up in the lexical scope OR the lexically scoped identifier did not exist on the type. + // Find a private identifier with the same description on the type. + let propertyOnType: Symbol | undefined; + const properties = getPropertiesOfType(leftType); + if (properties) { + forEach(properties, (symbol: Symbol) => { + const decl = symbol.valueDeclaration; + if (decl && isNamedDeclaration(decl) && isPrivateIdentifier(decl.name) && decl.name.escapedText === right.escapedText) { + propertyOnType = symbol; + return true; + } + }); + } + const diagName = diagnosticName(right); + if (propertyOnType) { + const typeValueDecl = Debug.checkDefined(propertyOnType.valueDeclaration); + const typeClass = Debug.checkDefined(getContainingClass(typeValueDecl)); + // We found a private identifier property with the same description. + // Either: + // - There is a lexically scoped private identifier AND it shadows the one we found on the type. + // - It is an attempt to access the private identifier outside of the class. + if (lexicallyScopedIdentifier?.valueDeclaration) { + const lexicalValueDecl = lexicallyScopedIdentifier.valueDeclaration; + const lexicalClass = getContainingClass(lexicalValueDecl); + Debug.assert(!!lexicalClass); + if (findAncestor(lexicalClass, n => typeClass === n)) { + const diagnostic = error( + right, + Diagnostics.The_property_0_cannot_be_accessed_on_type_1_within_this_class_because_it_is_shadowed_by_another_private_identifier_with_the_same_spelling, + diagName, + typeToString(leftType), + ); + + addRelatedInfo( + diagnostic, + createDiagnosticForNode( + lexicalValueDecl, + Diagnostics.The_shadowing_declaration_of_0_is_defined_here, + diagName, + ), + createDiagnosticForNode( + typeValueDecl, + Diagnostics.The_declaration_of_0_that_you_probably_intended_to_use_is_defined_here, + diagName, + ), + ); + return true; + } + } + error( + right, + Diagnostics.Property_0_is_not_accessible_outside_class_1_because_it_has_a_private_identifier, + diagName, + diagnosticName(typeClass.name || anon), + ); + return true; + } + return false; + } + + function isThisPropertyAccessInConstructor(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol) { + return (isConstructorDeclaredProperty(prop) || isThisProperty(node) && isAutoTypedProperty(prop)) + && getThisContainer(node, /*includeArrowFunctions*/ true, /*includeClassComputedPropertyName*/ false) === getDeclaringConstructor(prop); + } + + function checkPropertyAccessExpressionOrQualifiedName(node: PropertyAccessExpression | QualifiedName, left: Expression | QualifiedName, leftType: Type, right: Identifier | PrivateIdentifier, checkMode: CheckMode | undefined, writeOnly?: boolean) { + const parentSymbol = getNodeLinks(left).resolvedSymbol; + const assignmentKind = getAssignmentTargetKind(node); + const apparentType = getApparentType(assignmentKind !== AssignmentKind.None || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType); + const isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType; + let prop: Symbol | undefined; + if (isPrivateIdentifier(right)) { + if ( + languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators || + !useDefineForClassFields + ) { + if (assignmentKind !== AssignmentKind.None) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ClassPrivateFieldSet); + } + if (assignmentKind !== AssignmentKind.Definite) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ClassPrivateFieldGet); + } + } + + const lexicallyScopedSymbol = lookupSymbolForPrivateIdentifierDeclaration(right.escapedText, right); + if (assignmentKind && lexicallyScopedSymbol && lexicallyScopedSymbol.valueDeclaration && isMethodDeclaration(lexicallyScopedSymbol.valueDeclaration)) { + grammarErrorOnNode(right, Diagnostics.Cannot_assign_to_private_method_0_Private_methods_are_not_writable, idText(right)); + } + if (isAnyLike) { + if (lexicallyScopedSymbol) { + return isErrorType(apparentType) ? errorType : apparentType; + } + if (getContainingClassExcludingClassDecorators(right) === undefined) { + grammarErrorOnNode(right, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + return anyType; + } + } + + prop = lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(leftType, lexicallyScopedSymbol); + if (prop === undefined) { + // Check for private-identifier-specific shadowing and lexical-scoping errors. + if (checkPrivateIdentifierPropertyAccess(leftType, right, lexicallyScopedSymbol)) { + return errorType; + } + const containingClass = getContainingClassExcludingClassDecorators(right); + if (containingClass && isPlainJsFile(getSourceFileOfNode(containingClass), compilerOptions.checkJs)) { + grammarErrorOnNode(right, Diagnostics.Private_field_0_must_be_declared_in_an_enclosing_class, idText(right)); + } + } + else { + const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); + if (isSetonlyAccessor && assignmentKind !== AssignmentKind.Definite) { + error(node, Diagnostics.Private_accessor_was_defined_without_a_getter); + } + } + } + else { + if (isAnyLike) { + if (isIdentifier(left) && parentSymbol) { + markLinkedReferences(node, ReferenceHint.Property, /*propSymbol*/ undefined, leftType); + } + return isErrorType(apparentType) ? errorType : apparentType; + } + prop = getPropertyOfType(apparentType, right.escapedText, /*skipObjectFunctionPropertyAugment*/ isConstEnumObjectType(apparentType), /*includeTypeOnlyMembers*/ node.kind === SyntaxKind.QualifiedName); + } + markLinkedReferences(node, ReferenceHint.Property, prop, leftType); + + let propType: Type; + if (!prop) { + const indexInfo = !isPrivateIdentifier(right) && (assignmentKind === AssignmentKind.None || !isGenericObjectType(leftType) || isThisTypeParameter(leftType)) ? + getApplicableIndexInfoForName(apparentType, right.escapedText) : undefined; + if (!(indexInfo && indexInfo.type)) { + const isUncheckedJS = isUncheckedJSSuggestion(node, leftType.symbol, /*excludeClasses*/ true); + if (!isUncheckedJS && isJSLiteralType(leftType)) { + return anyType; + } + if (leftType.symbol === globalThisSymbol) { + if (globalThisSymbol.exports!.has(right.escapedText) && (globalThisSymbol.exports!.get(right.escapedText)!.flags & SymbolFlags.BlockScoped)) { + error(right, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(right.escapedText), typeToString(leftType)); + } + else if (noImplicitAny) { + error(right, Diagnostics.Element_implicitly_has_an_any_type_because_type_0_has_no_index_signature, typeToString(leftType)); + } + return anyType; + } + if (right.escapedText && !checkAndReportErrorForExtendingInterface(node)) { + reportNonexistentProperty(right, isThisTypeParameter(leftType) ? apparentType : leftType, isUncheckedJS); + } + return errorType; + } + if (indexInfo.isReadonly && (isAssignmentTarget(node) || isDeleteTarget(node))) { + error(node, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(apparentType)); + } + + propType = indexInfo.type; + if (compilerOptions.noUncheckedIndexedAccess && getAssignmentTargetKind(node) !== AssignmentKind.Definite) { + propType = getUnionType([propType, missingType]); + } + if (compilerOptions.noPropertyAccessFromIndexSignature && isPropertyAccessExpression(node)) { + error(right, Diagnostics.Property_0_comes_from_an_index_signature_so_it_must_be_accessed_with_0, unescapeLeadingUnderscores(right.escapedText)); + } + if (indexInfo.declaration && isDeprecatedDeclaration(indexInfo.declaration)) { + addDeprecatedSuggestion(right, [indexInfo.declaration], right.escapedText as string); + } + } + else { + const targetPropSymbol = resolveAliasWithDeprecationCheck(prop, right); + if (isDeprecatedSymbol(targetPropSymbol) && isUncalledFunctionReference(node, targetPropSymbol) && targetPropSymbol.declarations) { + addDeprecatedSuggestion(right, targetPropSymbol.declarations, right.escapedText as string); + } + checkPropertyNotUsedBeforeDeclaration(prop, node, right); + markPropertyAsReferenced(prop, node, isSelfTypeAccess(left, parentSymbol)); + getNodeLinks(node).resolvedSymbol = prop; + checkPropertyAccessibility(node, left.kind === SyntaxKind.SuperKeyword, isWriteAccess(node), apparentType, prop); + if (isAssignmentToReadonlyEntity(node as Expression, prop, assignmentKind)) { + error(right, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, idText(right)); + return errorType; + } + + propType = isThisPropertyAccessInConstructor(node, prop) ? autoType : writeOnly || isWriteOnlyAccess(node) ? getWriteTypeOfSymbol(prop) : getTypeOfSymbol(prop); + } + + return getFlowTypeOfAccessExpression(node, prop, propType, right, checkMode); + } + + /** + * Determines whether a did-you-mean error should be a suggestion in an unchecked JS file. + * Only applies to unchecked JS files without checkJS, // @ts-check or // @ts-nocheck + * It does not suggest when the suggestion: + * - Is from a global file that is different from the reference file, or + * - (optionally) Is a class, or is a this.x property access expression + */ + function isUncheckedJSSuggestion(node: Node | undefined, suggestion: Symbol | undefined, excludeClasses: boolean): boolean { + const file = getSourceFileOfNode(node); + if (file) { + if (compilerOptions.checkJs === undefined && file.checkJsDirective === undefined && (file.scriptKind === ScriptKind.JS || file.scriptKind === ScriptKind.JSX)) { + const declarationFile = forEach(suggestion?.declarations, getSourceFileOfNode); + const suggestionHasNoExtendsOrDecorators = !suggestion?.valueDeclaration + || !isClassLike(suggestion.valueDeclaration) + || suggestion.valueDeclaration.heritageClauses?.length + || classOrConstructorParameterIsDecorated(/*useLegacyDecorators*/ false, suggestion.valueDeclaration); + return !(file !== declarationFile && !!declarationFile && isGlobalSourceFile(declarationFile)) + && !(excludeClasses && suggestion && suggestion.flags & SymbolFlags.Class && suggestionHasNoExtendsOrDecorators) + && !(!!node && excludeClasses && isPropertyAccessExpression(node) && node.expression.kind === SyntaxKind.ThisKeyword && suggestionHasNoExtendsOrDecorators); + } + } + return false; + } + + function getFlowTypeOfAccessExpression(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol | undefined, propType: Type, errorNode: Node, checkMode: CheckMode | undefined) { + // Only compute control flow type if this is a property access expression that isn't an + // assignment target, and the referenced property was declared as a variable, property, + // accessor, or optional method. + const assignmentKind = getAssignmentTargetKind(node); + if (assignmentKind === AssignmentKind.Definite) { + return removeMissingType(propType, !!(prop && prop.flags & SymbolFlags.Optional)); + } + if ( + prop && + !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) + && !(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union) + && !isDuplicatedCommonJSExport(prop.declarations) + ) { + return propType; + } + if (propType === autoType) { + return getFlowTypeOfProperty(node, prop); + } + propType = getNarrowableTypeForReference(propType, node, checkMode); + // If strict null checks and strict property initialization checks are enabled, if we have + // a this.xxx property access, if the property is an instance property without an initializer, + // and if we are in a constructor of the same class as the property declaration, assume that + // the property is uninitialized at the top of the control flow. + let assumeUninitialized = false; + if (strictNullChecks && strictPropertyInitialization && isAccessExpression(node) && node.expression.kind === SyntaxKind.ThisKeyword) { + const declaration = prop && prop.valueDeclaration; + if (declaration && isPropertyWithoutInitializer(declaration)) { + if (!isStatic(declaration)) { + const flowContainer = getControlFlowContainer(node); + if (flowContainer.kind === SyntaxKind.Constructor && flowContainer.parent === declaration.parent && !(declaration.flags & NodeFlags.Ambient)) { + assumeUninitialized = true; + } + } + } + } + else if ( + strictNullChecks && prop && prop.valueDeclaration && + isPropertyAccessExpression(prop.valueDeclaration) && + getAssignmentDeclarationPropertyAccessKind(prop.valueDeclaration) && + getControlFlowContainer(node) === getControlFlowContainer(prop.valueDeclaration) + ) { + assumeUninitialized = true; + } + const flowType = getFlowTypeOfReference(node, propType, assumeUninitialized ? getOptionalType(propType) : propType); + if (assumeUninitialized && !containsUndefinedType(propType) && containsUndefinedType(flowType)) { + error(errorNode, Diagnostics.Property_0_is_used_before_being_assigned, symbolToString(prop!)); // TODO: GH#18217 + // Return the declared type to reduce follow-on errors + return propType; + } + return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType; + } + + function checkPropertyNotUsedBeforeDeclaration(prop: Symbol, node: PropertyAccessExpression | QualifiedName, right: Identifier | PrivateIdentifier): void { + const { valueDeclaration } = prop; + if (!valueDeclaration || getSourceFileOfNode(node).isDeclarationFile) { + return; + } + + let diagnosticMessage; + const declarationName = idText(right); + if ( + isInPropertyInitializerOrClassStaticBlock(node) + && !isOptionalPropertyDeclaration(valueDeclaration) + && !(isAccessExpression(node) && isAccessExpression(node.expression)) + && !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right) + && !(isMethodDeclaration(valueDeclaration) && getCombinedModifierFlagsCached(valueDeclaration) & ModifierFlags.Static) + && (useDefineForClassFields || !isPropertyDeclaredInAncestorClass(prop)) + ) { + diagnosticMessage = error(right, Diagnostics.Property_0_is_used_before_its_initialization, declarationName); + } + else if ( + valueDeclaration.kind === SyntaxKind.ClassDeclaration && + node.parent.kind !== SyntaxKind.TypeReference && + !(valueDeclaration.flags & NodeFlags.Ambient) && + !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right) + ) { + diagnosticMessage = error(right, Diagnostics.Class_0_used_before_its_declaration, declarationName); + } + + if (diagnosticMessage) { + addRelatedInfo(diagnosticMessage, createDiagnosticForNode(valueDeclaration, Diagnostics._0_is_declared_here, declarationName)); + } + } + + function isInPropertyInitializerOrClassStaticBlock(node: Node): boolean { + return !!findAncestor(node, node => { + switch (node.kind) { + case SyntaxKind.PropertyDeclaration: + return true; + case SyntaxKind.PropertyAssignment: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.SpreadAssignment: + case SyntaxKind.ComputedPropertyName: + case SyntaxKind.TemplateSpan: + case SyntaxKind.JsxExpression: + case SyntaxKind.JsxAttribute: + case SyntaxKind.JsxAttributes: + case SyntaxKind.JsxSpreadAttribute: + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.ExpressionWithTypeArguments: + case SyntaxKind.HeritageClause: + return false; + case SyntaxKind.ArrowFunction: + case SyntaxKind.ExpressionStatement: + return isBlock(node.parent) && isClassStaticBlockDeclaration(node.parent.parent) ? true : "quit"; + default: + return isExpressionNode(node) ? false : "quit"; + } + }); + } + + /** + * It's possible that "prop.valueDeclaration" is a local declaration, but the property was also declared in a superclass. + * In that case we won't consider it used before its declaration, because it gets its value from the superclass' declaration. + */ + function isPropertyDeclaredInAncestorClass(prop: Symbol): boolean { + if (!(prop.parent!.flags & SymbolFlags.Class)) { + return false; + } + let classType: InterfaceType | undefined = getTypeOfSymbol(prop.parent!) as InterfaceType; + while (true) { + classType = classType.symbol && getSuperClass(classType) as InterfaceType | undefined; + if (!classType) { + return false; + } + const superProperty = getPropertyOfType(classType, prop.escapedName); + if (superProperty && superProperty.valueDeclaration) { + return true; + } + } + } + + function getSuperClass(classType: InterfaceType): Type | undefined { + const x = getBaseTypes(classType); + if (x.length === 0) { + return undefined; + } + return getIntersectionType(x); + } + + function reportNonexistentProperty(propNode: Identifier | PrivateIdentifier, containingType: Type, isUncheckedJS: boolean) { + let errorInfo: DiagnosticMessageChain | undefined; + let relatedInfo: Diagnostic | undefined; + if (!isPrivateIdentifier(propNode) && containingType.flags & TypeFlags.Union && !(containingType.flags & TypeFlags.Primitive)) { + for (const subtype of (containingType as UnionType).types) { + if (!getPropertyOfType(subtype, propNode.escapedText) && !getApplicableIndexInfoForName(subtype, propNode.escapedText)) { + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1, declarationNameToString(propNode), typeToString(subtype)); + break; + } + } + } + if (typeHasStaticProperty(propNode.escapedText, containingType)) { + const propName = declarationNameToString(propNode); + const typeName = typeToString(containingType); + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_to_access_the_static_member_2_instead, propName, typeName, typeName + "." + propName); + } + else { + const promisedType = getPromisedTypeOfPromise(containingType); + if (promisedType && getPropertyOfType(promisedType, propNode.escapedText)) { + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1, declarationNameToString(propNode), typeToString(containingType)); + relatedInfo = createDiagnosticForNode(propNode, Diagnostics.Did_you_forget_to_use_await); + } + else { + const missingProperty = declarationNameToString(propNode); + const container = typeToString(containingType); + const libSuggestion = getSuggestedLibForNonExistentProperty(missingProperty, containingType); + if (libSuggestion !== undefined) { + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_2_or_later, missingProperty, container, libSuggestion); + } + else { + const suggestion = getSuggestedSymbolForNonexistentProperty(propNode, containingType); + if (suggestion !== undefined) { + const suggestedName = symbolName(suggestion); + const message = isUncheckedJS ? Diagnostics.Property_0_may_not_exist_on_type_1_Did_you_mean_2 : Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2; + errorInfo = chainDiagnosticMessages(errorInfo, message, missingProperty, container, suggestedName); + relatedInfo = suggestion.valueDeclaration && createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestedName); + } + else { + const diagnostic = containerSeemsToBeEmptyDomElement(containingType) + ? Diagnostics.Property_0_does_not_exist_on_type_1_Try_changing_the_lib_compiler_option_to_include_dom + : Diagnostics.Property_0_does_not_exist_on_type_1; + errorInfo = chainDiagnosticMessages(elaborateNeverIntersection(errorInfo, containingType), diagnostic, missingProperty, container); + } + } + } + } + const resultDiagnostic = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(propNode), propNode, errorInfo); + if (relatedInfo) { + addRelatedInfo(resultDiagnostic, relatedInfo); + } + addErrorOrSuggestion(!isUncheckedJS || errorInfo.code !== Diagnostics.Property_0_may_not_exist_on_type_1_Did_you_mean_2.code, resultDiagnostic); + } + + function containerSeemsToBeEmptyDomElement(containingType: Type) { + return (compilerOptions.lib && !compilerOptions.lib.includes("dom")) && + everyContainedType(containingType, type => type.symbol && /^(EventTarget|Node|((HTML[a-zA-Z]*)?Element))$/.test(unescapeLeadingUnderscores(type.symbol.escapedName))) && + isEmptyObjectType(containingType); + } + + function typeHasStaticProperty(propName: __String, containingType: Type): boolean { + const prop = containingType.symbol && getPropertyOfType(getTypeOfSymbol(containingType.symbol), propName); + return prop !== undefined && !!prop.valueDeclaration && isStatic(prop.valueDeclaration); + } + + function getSuggestedLibForNonExistentName(name: __String | Identifier) { + const missingName = diagnosticName(name); + const allFeatures = getScriptTargetFeatures(); + const typeFeatures = allFeatures.get(missingName); + return typeFeatures && firstIterator(typeFeatures.keys()); + } + + function getSuggestedLibForNonExistentProperty(missingProperty: string, containingType: Type) { + const container = getApparentType(containingType).symbol; + if (!container) { + return undefined; + } + const containingTypeName = symbolName(container); + const allFeatures = getScriptTargetFeatures(); + const typeFeatures = allFeatures.get(containingTypeName); + if (typeFeatures) { + for (const [libTarget, featuresOfType] of typeFeatures) { + if (contains(featuresOfType, missingProperty)) { + return libTarget; + } + } + } + } + + function getSuggestedSymbolForNonexistentClassMember(name: string, baseType: Type): Symbol | undefined { + return getSpellingSuggestionForName(name, getPropertiesOfType(baseType), SymbolFlags.ClassMember); + } + + function getSuggestedSymbolForNonexistentProperty(name: Identifier | PrivateIdentifier | string, containingType: Type): Symbol | undefined { + let props = getPropertiesOfType(containingType); + if (typeof name !== "string") { + const parent = name.parent; + if (isPropertyAccessExpression(parent)) { + props = filter(props, prop => isValidPropertyAccessForCompletions(parent, containingType, prop)); + } + name = idText(name); + } + return getSpellingSuggestionForName(name, props, SymbolFlags.Value); + } + + function getSuggestedSymbolForNonexistentJSXAttribute(name: Identifier | PrivateIdentifier | string, containingType: Type): Symbol | undefined { + const strName = isString(name) ? name : idText(name); + const properties = getPropertiesOfType(containingType); + const jsxSpecific = strName === "for" ? find(properties, x => symbolName(x) === "htmlFor") + : strName === "class" ? find(properties, x => symbolName(x) === "className") + : undefined; + return jsxSpecific ?? getSpellingSuggestionForName(strName, properties, SymbolFlags.Value); + } + + function getSuggestionForNonexistentProperty(name: Identifier | PrivateIdentifier | string, containingType: Type): string | undefined { + const suggestion = getSuggestedSymbolForNonexistentProperty(name, containingType); + return suggestion && symbolName(suggestion); + } + + function getSuggestionForSymbolNameLookup(symbols: SymbolTable, name: __String, meaning: SymbolFlags) { + const symbol = getSymbol(symbols, name, meaning); + // Sometimes the symbol is found when location is a return type of a function: `typeof x` and `x` is declared in the body of the function + // So the table *contains* `x` but `x` isn't actually in scope. + // However, resolveNameHelper will continue and call this callback again, so we'll eventually get a correct suggestion. + if (symbol) return symbol; + let candidates: Symbol[]; + if (symbols === globals) { + const primitives = mapDefined( + ["string", "number", "boolean", "object", "bigint", "symbol"], + s => symbols.has((s.charAt(0).toUpperCase() + s.slice(1)) as __String) + ? createSymbol(SymbolFlags.TypeAlias, s as __String) as Symbol + : undefined, + ); + candidates = primitives.concat(arrayFrom(symbols.values())); + } + else { + candidates = arrayFrom(symbols.values()); + } + return getSpellingSuggestionForName(unescapeLeadingUnderscores(name), candidates, meaning); + } + function getSuggestedSymbolForNonexistentSymbol(location: Node | undefined, outerName: __String, meaning: SymbolFlags): Symbol | undefined { + Debug.assert(outerName !== undefined, "outername should always be defined"); + const result = resolveNameForSymbolSuggestion(location, outerName, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false, /*excludeGlobals*/ false); + return result; + } + + function getSuggestedSymbolForNonexistentModule(name: Identifier, targetModule: Symbol): Symbol | undefined { + return targetModule.exports && getSpellingSuggestionForName(idText(name), getExportsOfModuleAsArray(targetModule), SymbolFlags.ModuleMember); + } + + function getSuggestionForNonexistentIndexSignature(objectType: Type, expr: ElementAccessExpression, keyedType: Type): string | undefined { + // check if object type has setter or getter + function hasProp(name: "set" | "get") { + const prop = getPropertyOfObjectType(objectType, name as __String); + if (prop) { + const s = getSingleCallSignature(getTypeOfSymbol(prop)); + return !!s && getMinArgumentCount(s) >= 1 && isTypeAssignableTo(keyedType, getTypeAtPosition(s, 0)); + } + return false; + } + + const suggestedMethod = isAssignmentTarget(expr) ? "set" : "get"; + if (!hasProp(suggestedMethod)) { + return undefined; + } + + let suggestion = tryGetPropertyAccessOrIdentifierToString(expr.expression); + if (suggestion === undefined) { + suggestion = suggestedMethod; + } + else { + suggestion += "." + suggestedMethod; + } + + return suggestion; + } + + function getSuggestedTypeForNonexistentStringLiteralType(source: StringLiteralType, target: UnionType): StringLiteralType | undefined { + const candidates = target.types.filter((type): type is StringLiteralType => !!(type.flags & TypeFlags.StringLiteral)); + return getSpellingSuggestion(source.value, candidates, type => type.value); + } + + /** + * Given a name and a list of symbols whose names are *not* equal to the name, return a spelling suggestion if there is one that is close enough. + * Names less than length 3 only check for case-insensitive equality, not levenshtein distance. + * + * If there is a candidate that's the same except for case, return that. + * If there is a candidate that's within one edit of the name, return that. + * Otherwise, return the candidate with the smallest Levenshtein distance, + * except for candidates: + * * With no name + * * Whose meaning doesn't match the `meaning` parameter. + * * Whose length differs from the target name by more than 0.34 of the length of the name. + * * Whose levenshtein distance is more than 0.4 of the length of the name + * (0.4 allows 1 substitution/transposition for every 5 characters, + * and 1 insertion/deletion at 3 characters) + */ + function getSpellingSuggestionForName(name: string, symbols: Symbol[], meaning: SymbolFlags): Symbol | undefined { + return getSpellingSuggestion(name, symbols, getCandidateName); + + function getCandidateName(candidate: Symbol) { + const candidateName = symbolName(candidate); + if (startsWith(candidateName, '"')) { + return undefined; + } + + if (candidate.flags & meaning) { + return candidateName; + } + + if (candidate.flags & SymbolFlags.Alias) { + const alias = tryResolveAlias(candidate); + if (alias && alias.flags & meaning) { + return candidateName; + } + } + + return undefined; + } + } + + function markPropertyAsReferenced(prop: Symbol, nodeForCheckWriteOnly: Node | undefined, isSelfTypeAccess: boolean) { + const valueDeclaration = prop && (prop.flags & SymbolFlags.ClassMember) && prop.valueDeclaration; + if (!valueDeclaration) { + return; + } + const hasPrivateModifier = hasEffectiveModifier(valueDeclaration, ModifierFlags.Private); + const hasPrivateIdentifier = prop.valueDeclaration && isNamedDeclaration(prop.valueDeclaration) && isPrivateIdentifier(prop.valueDeclaration.name); + if (!hasPrivateModifier && !hasPrivateIdentifier) { + return; + } + if (nodeForCheckWriteOnly && isWriteOnlyAccess(nodeForCheckWriteOnly) && !(prop.flags & SymbolFlags.SetAccessor)) { + return; + } + if (isSelfTypeAccess) { + // Find any FunctionLikeDeclaration because those create a new 'this' binding. But this should only matter for methods (or getters/setters). + const containingMethod = findAncestor(nodeForCheckWriteOnly, isFunctionLikeDeclaration); + if (containingMethod && containingMethod.symbol === prop) { + return; + } + } + + (getCheckFlags(prop) & CheckFlags.Instantiated ? getSymbolLinks(prop).target : prop)!.isReferenced = SymbolFlags.All; + } + + function isSelfTypeAccess(name: Expression | QualifiedName, parent: Symbol | undefined) { + return name.kind === SyntaxKind.ThisKeyword + || !!parent && isEntityNameExpression(name) && parent === getResolvedSymbol(getFirstIdentifier(name)); + } + + function isValidPropertyAccess(node: PropertyAccessExpression | QualifiedName | ImportTypeNode, propertyName: __String): boolean { + switch (node.kind) { + case SyntaxKind.PropertyAccessExpression: + return isValidPropertyAccessWithType(node, node.expression.kind === SyntaxKind.SuperKeyword, propertyName, getWidenedType(checkExpression(node.expression))); + case SyntaxKind.QualifiedName: + return isValidPropertyAccessWithType(node, /*isSuper*/ false, propertyName, getWidenedType(checkExpression(node.left))); + case SyntaxKind.ImportType: + return isValidPropertyAccessWithType(node, /*isSuper*/ false, propertyName, getTypeFromTypeNode(node)); + } + } + + /** + * Checks if an existing property access is valid for completions purposes. + * @param node a property access-like node where we want to check if we can access a property. + * This node does not need to be an access of the property we are checking. + * e.g. in completions, this node will often be an incomplete property access node, as in `foo.`. + * Besides providing a location (i.e. scope) used to check property accessibility, we use this node for + * computing whether this is a `super` property access. + * @param type the type whose property we are checking. + * @param property the accessed property's symbol. + */ + function isValidPropertyAccessForCompletions(node: PropertyAccessExpression | ImportTypeNode | QualifiedName, type: Type, property: Symbol): boolean { + return isPropertyAccessible(node, node.kind === SyntaxKind.PropertyAccessExpression && node.expression.kind === SyntaxKind.SuperKeyword, /*isWrite*/ false, type, property); + // Previously we validated the 'this' type of methods but this adversely affected performance. See #31377 for more context. + } + + function isValidPropertyAccessWithType( + node: PropertyAccessExpression | QualifiedName | ImportTypeNode, + isSuper: boolean, + propertyName: __String, + type: Type, + ): boolean { + // Short-circuiting for improved performance. + if (isTypeAny(type)) { + return true; + } + + const prop = getPropertyOfType(type, propertyName); + return !!prop && isPropertyAccessible(node, isSuper, /*isWrite*/ false, type, prop); + } + + /** + * Checks if a property can be accessed in a location. + * The location is given by the `node` parameter. + * The node does not need to be a property access. + * @param node location where to check property accessibility + * @param isSuper whether to consider this a `super` property access, e.g. `super.foo`. + * @param isWrite whether this is a write access, e.g. `++foo.x`. + * @param containingType type where the property comes from. + * @param property property symbol. + */ + function isPropertyAccessible( + node: Node, + isSuper: boolean, + isWrite: boolean, + containingType: Type, + property: Symbol, + ): boolean { + // Short-circuiting for improved performance. + if (isTypeAny(containingType)) { + return true; + } + + // A #private property access in an optional chain is an error dealt with by the parser. + // The checker does not check for it, so we need to do our own check here. + if (property.valueDeclaration && isPrivateIdentifierClassElementDeclaration(property.valueDeclaration)) { + const declClass = getContainingClass(property.valueDeclaration); + return !isOptionalChain(node) && !!findAncestor(node, parent => parent === declClass); + } + + return checkPropertyAccessibilityAtLocation(node, isSuper, isWrite, containingType, property); + } + + /** + * Return the symbol of the for-in variable declared or referenced by the given for-in statement. + */ + function getForInVariableSymbol(node: ForInStatement): Symbol | undefined { + const initializer = node.initializer; + if (initializer.kind === SyntaxKind.VariableDeclarationList) { + const variable = (initializer as VariableDeclarationList).declarations[0]; + if (variable && !isBindingPattern(variable.name)) { + return getSymbolOfDeclaration(variable); + } + } + else if (initializer.kind === SyntaxKind.Identifier) { + return getResolvedSymbol(initializer as Identifier); + } + return undefined; + } + + /** + * Return true if the given type is considered to have numeric property names. + */ + function hasNumericPropertyNames(type: Type) { + return getIndexInfosOfType(type).length === 1 && !!getIndexInfoOfType(type, numberType); + } + + /** + * Return true if given node is an expression consisting of an identifier (possibly parenthesized) + * that references a for-in variable for an object with numeric property names. + */ + function isForInVariableForNumericPropertyNames(expr: Expression) { + const e = skipParentheses(expr); + if (e.kind === SyntaxKind.Identifier) { + const symbol = getResolvedSymbol(e as Identifier); + if (symbol.flags & SymbolFlags.Variable) { + let child: Node = expr; + let node = expr.parent; + while (node) { + if ( + node.kind === SyntaxKind.ForInStatement && + child === (node as ForInStatement).statement && + getForInVariableSymbol(node as ForInStatement) === symbol && + hasNumericPropertyNames(getTypeOfExpression((node as ForInStatement).expression)) + ) { + return true; + } + child = node; + node = node.parent; + } + } + } + return false; + } + + function checkIndexedAccess(node: ElementAccessExpression, checkMode: CheckMode | undefined): Type { + return node.flags & NodeFlags.OptionalChain ? checkElementAccessChain(node as ElementAccessChain, checkMode) : + checkElementAccessExpression(node, checkNonNullExpression(node.expression), checkMode); + } + + function checkElementAccessChain(node: ElementAccessChain, checkMode: CheckMode | undefined) { + const exprType = checkExpression(node.expression); + const nonOptionalType = getOptionalExpressionType(exprType, node.expression); + return propagateOptionalTypeMarker(checkElementAccessExpression(node, checkNonNullType(nonOptionalType, node.expression), checkMode), node, nonOptionalType !== exprType); + } + + function checkElementAccessExpression(node: ElementAccessExpression, exprType: Type, checkMode: CheckMode | undefined): Type { + const objectType = getAssignmentTargetKind(node) !== AssignmentKind.None || isMethodAccessForCall(node) ? getWidenedType(exprType) : exprType; + const indexExpression = node.argumentExpression; + const indexType = checkExpression(indexExpression); + + if (isErrorType(objectType) || objectType === silentNeverType) { + return objectType; + } + + if (isConstEnumObjectType(objectType) && !isStringLiteralLike(indexExpression)) { + error(indexExpression, Diagnostics.A_const_enum_member_can_only_be_accessed_using_a_string_literal); + return errorType; + } + + const effectiveIndexType = isForInVariableForNumericPropertyNames(indexExpression) ? numberType : indexType; + const assignmentTargetKind = getAssignmentTargetKind(node); + let accessFlags: AccessFlags; + if (assignmentTargetKind === AssignmentKind.None) { + accessFlags = AccessFlags.ExpressionPosition; + } + else { + accessFlags = AccessFlags.Writing | (isGenericObjectType(objectType) && !isThisTypeParameter(objectType) ? AccessFlags.NoIndexSignatures : 0); + if (assignmentTargetKind === AssignmentKind.Compound) { + accessFlags |= AccessFlags.ExpressionPosition; + } + } + const indexedAccessType = getIndexedAccessTypeOrUndefined(objectType, effectiveIndexType, accessFlags, node) || errorType; + return checkIndexedAccessIndexType(getFlowTypeOfAccessExpression(node, getNodeLinks(node).resolvedSymbol, indexedAccessType, indexExpression, checkMode), node); + } + + function callLikeExpressionMayHaveTypeArguments(node: CallLikeExpression): node is CallExpression | NewExpression | TaggedTemplateExpression | JsxOpeningElement { + return isCallOrNewExpression(node) || isTaggedTemplateExpression(node) || isJsxOpeningLikeElement(node); + } + + function resolveUntypedCall(node: CallLikeExpression): Signature { + if (callLikeExpressionMayHaveTypeArguments(node)) { + // Check type arguments even though we will give an error that untyped calls may not accept type arguments. + // This gets us diagnostics for the type arguments and marks them as referenced. + forEach(node.typeArguments, checkSourceElement); + } + + if (node.kind === SyntaxKind.TaggedTemplateExpression) { + checkExpression(node.template); + } + else if (isJsxOpeningLikeElement(node)) { + checkExpression(node.attributes); + } + else if (isBinaryExpression(node)) { + checkExpression(node.left); + } + else if (isCallOrNewExpression(node)) { + forEach(node.arguments, argument => { + checkExpression(argument); + }); + } + return anySignature; + } + + function resolveErrorCall(node: CallLikeExpression): Signature { + resolveUntypedCall(node); + return unknownSignature; + } + + // Re-order candidate signatures into the result array. Assumes the result array to be empty. + // The candidate list orders groups in reverse, but within a group signatures are kept in declaration order + // A nit here is that we reorder only signatures that belong to the same symbol, + // so order how inherited signatures are processed is still preserved. + // interface A { (x: string): void } + // interface B extends A { (x: 'foo'): string } + // const b: B; + // b('foo') // <- here overloads should be processed as [(x:'foo'): string, (x: string): void] + function reorderCandidates(signatures: readonly Signature[], result: Signature[], callChainFlags: SignatureFlags): void { + let lastParent: Node | undefined; + let lastSymbol: Symbol | undefined; + let cutoffIndex = 0; + let index: number | undefined; + let specializedIndex = -1; + let spliceIndex: number; + Debug.assert(!result.length); + for (const signature of signatures) { + const symbol = signature.declaration && getSymbolOfDeclaration(signature.declaration); + const parent = signature.declaration && signature.declaration.parent; + if (!lastSymbol || symbol === lastSymbol) { + if (lastParent && parent === lastParent) { + index = index! + 1; + } + else { + lastParent = parent; + index = cutoffIndex; + } + } + else { + // current declaration belongs to a different symbol + // set cutoffIndex so re-orderings in the future won't change result set from 0 to cutoffIndex + index = cutoffIndex = result.length; + lastParent = parent; + } + lastSymbol = symbol; + + // specialized signatures always need to be placed before non-specialized signatures regardless + // of the cutoff position; see GH#1133 + if (signatureHasLiteralTypes(signature)) { + specializedIndex++; + spliceIndex = specializedIndex; + // The cutoff index always needs to be greater than or equal to the specialized signature index + // in order to prevent non-specialized signatures from being added before a specialized + // signature. + cutoffIndex++; + } + else { + spliceIndex = index; + } + + result.splice(spliceIndex, 0, callChainFlags ? getOptionalCallSignature(signature, callChainFlags) : signature); + } + } + + function isSpreadArgument(arg: Expression | undefined): arg is Expression { + return !!arg && (arg.kind === SyntaxKind.SpreadElement || arg.kind === SyntaxKind.SyntheticExpression && (arg as SyntheticExpression).isSpread); + } + + function getSpreadArgumentIndex(args: readonly Expression[]): number { + return findIndex(args, isSpreadArgument); + } + + function acceptsVoid(t: Type): boolean { + return !!(t.flags & TypeFlags.Void); + } + + function acceptsVoidUndefinedUnknownOrAny(t: Type): boolean { + return !!(t.flags & (TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Unknown | TypeFlags.Any)); + } + + function hasCorrectArity(node: CallLikeExpression, args: readonly Expression[], signature: Signature, signatureHelpTrailingComma = false) { + let argCount: number; + let callIsIncomplete = false; // In incomplete call we want to be lenient when we have too few arguments + let effectiveParameterCount = getParameterCount(signature); + let effectiveMinimumArguments = getMinArgumentCount(signature); + + if (node.kind === SyntaxKind.TaggedTemplateExpression) { + argCount = args.length; + if (node.template.kind === SyntaxKind.TemplateExpression) { + // If a tagged template expression lacks a tail literal, the call is incomplete. + // Specifically, a template only can end in a TemplateTail or a Missing literal. + const lastSpan = last(node.template.templateSpans); // we should always have at least one span. + callIsIncomplete = nodeIsMissing(lastSpan.literal) || !!lastSpan.literal.isUnterminated; + } + else { + // If the template didn't end in a backtick, or its beginning occurred right prior to EOF, + // then this might actually turn out to be a TemplateHead in the future; + // so we consider the call to be incomplete. + const templateLiteral = node.template as LiteralExpression; + Debug.assert(templateLiteral.kind === SyntaxKind.NoSubstitutionTemplateLiteral); + callIsIncomplete = !!templateLiteral.isUnterminated; + } + } + else if (node.kind === SyntaxKind.Decorator) { + argCount = getDecoratorArgumentCount(node, signature); + } + else if (node.kind === SyntaxKind.BinaryExpression) { + argCount = 1; + } + else if (isJsxOpeningLikeElement(node)) { + callIsIncomplete = node.attributes.end === node.end; + if (callIsIncomplete) { + return true; + } + argCount = effectiveMinimumArguments === 0 ? args.length : 1; + effectiveParameterCount = args.length === 0 ? effectiveParameterCount : 1; // class may have argumentless ctor functions - still resolve ctor and compare vs props member type + effectiveMinimumArguments = Math.min(effectiveMinimumArguments, 1); // sfc may specify context argument - handled by framework and not typechecked + } + else if (!node.arguments) { + // This only happens when we have something of the form: 'new C' + Debug.assert(node.kind === SyntaxKind.NewExpression); + return getMinArgumentCount(signature) === 0; + } + else { + argCount = signatureHelpTrailingComma ? args.length + 1 : args.length; + + // If we are missing the close parenthesis, the call is incomplete. + callIsIncomplete = node.arguments.end === node.end; + + // If a spread argument is present, check that it corresponds to a rest parameter or at least that it's in the valid range. + const spreadArgIndex = getSpreadArgumentIndex(args); + if (spreadArgIndex >= 0) { + return spreadArgIndex >= getMinArgumentCount(signature) && (hasEffectiveRestParameter(signature) || spreadArgIndex < getParameterCount(signature)); + } + } + + // Too many arguments implies incorrect arity. + if (!hasEffectiveRestParameter(signature) && argCount > effectiveParameterCount) { + return false; + } + + // If the call is incomplete, we should skip the lower bound check. + // JSX signatures can have extra parameters provided by the library which we don't check + if (callIsIncomplete || argCount >= effectiveMinimumArguments) { + return true; + } + for (let i = argCount; i < effectiveMinimumArguments; i++) { + const type = getTypeAtPosition(signature, i); + if (filterType(type, isInJSFile(node) && !strictNullChecks ? acceptsVoidUndefinedUnknownOrAny : acceptsVoid).flags & TypeFlags.Never) { + return false; + } + } + return true; + } + + function hasCorrectTypeArgumentArity(signature: Signature, typeArguments: NodeArray | undefined) { + // If the user supplied type arguments, but the number of type arguments does not match + // the declared number of type parameters, the call has an incorrect arity. + const numTypeParameters = length(signature.typeParameters); + const minTypeArgumentCount = getMinTypeArgumentCount(signature.typeParameters); + return !some(typeArguments) || + (typeArguments.length >= minTypeArgumentCount && typeArguments.length <= numTypeParameters); + } + + function isInstantiatedGenericParameter(signature: Signature, pos: number) { + let type; + return !!(signature.target && (type = tryGetTypeAtPosition(signature.target, pos)) && isGenericType(type)); + } + + // If type has a single call signature and no other members, return that signature. Otherwise, return undefined. + function getSingleCallSignature(type: Type): Signature | undefined { + return getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ false); + } + + function getSingleCallOrConstructSignature(type: Type): Signature | undefined { + return getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ false) || + getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ false); + } + + function getSingleSignature(type: Type, kind: SignatureKind, allowMembers: boolean): Signature | undefined { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + if (allowMembers || resolved.properties.length === 0 && resolved.indexInfos.length === 0) { + if (kind === SignatureKind.Call && resolved.callSignatures.length === 1 && resolved.constructSignatures.length === 0) { + return resolved.callSignatures[0]; + } + if (kind === SignatureKind.Construct && resolved.constructSignatures.length === 1 && resolved.callSignatures.length === 0) { + return resolved.constructSignatures[0]; + } + } + } + return undefined; + } + + // Instantiate a generic signature in the context of a non-generic signature (section 3.8.5 in TypeScript spec) + function instantiateSignatureInContextOf(signature: Signature, contextualSignature: Signature, inferenceContext?: InferenceContext, compareTypes?: TypeComparer): Signature { + const context = createInferenceContext(signature.typeParameters!, signature, InferenceFlags.None, compareTypes); + // We clone the inferenceContext to avoid fixing. For example, when the source signature is (x: T) => T[] and + // the contextual signature is (...args: A) => B, we want to infer the element type of A's constraint (say 'any') + // for T but leave it possible to later infer '[any]' back to A. + const restType = getEffectiveRestType(contextualSignature); + const mapper = inferenceContext && (restType && restType.flags & TypeFlags.TypeParameter ? inferenceContext.nonFixingMapper : inferenceContext.mapper); + const sourceSignature = mapper ? instantiateSignature(contextualSignature, mapper) : contextualSignature; + applyToParameterTypes(sourceSignature, signature, (source, target) => { + // Type parameters from outer context referenced by source type are fixed by instantiation of the source type + inferTypes(context.inferences, source, target); + }); + if (!inferenceContext) { + applyToReturnTypes(contextualSignature, signature, (source, target) => { + inferTypes(context.inferences, source, target, InferencePriority.ReturnType); + }); + } + return getSignatureInstantiation(signature, getInferredTypes(context), isInJSFile(contextualSignature.declaration)); + } + + function inferJsxTypeArguments(node: JsxOpeningLikeElement, signature: Signature, checkMode: CheckMode, context: InferenceContext): Type[] { + const paramType = getEffectiveFirstArgumentForJsxSignature(signature, node); + const checkAttrType = checkExpressionWithContextualType(node.attributes, paramType, context, checkMode); + inferTypes(context.inferences, checkAttrType, paramType); + return getInferredTypes(context); + } + + function getThisArgumentType(thisArgumentNode: Expression | undefined) { + if (!thisArgumentNode) { + return voidType; + } + const thisArgumentType = checkExpression(thisArgumentNode); + return isRightSideOfInstanceofExpression(thisArgumentNode) ? thisArgumentType : + isOptionalChainRoot(thisArgumentNode.parent) ? getNonNullableType(thisArgumentType) : + isOptionalChain(thisArgumentNode.parent) ? removeOptionalTypeMarker(thisArgumentType) : + thisArgumentType; + } + + function inferTypeArguments(node: CallLikeExpression, signature: Signature, args: readonly Expression[], checkMode: CheckMode, context: InferenceContext): Type[] { + if (isJsxOpeningLikeElement(node)) { + return inferJsxTypeArguments(node, signature, checkMode, context); + } + + // If a contextual type is available, infer from that type to the return type of the call expression. For + // example, given a 'function wrap(cb: (x: T) => U): (x: T) => U' and a call expression + // 'let f: (x: string) => number = wrap(s => s.length)', we infer from the declared type of 'f' to the + // return type of 'wrap'. + if (node.kind !== SyntaxKind.Decorator && node.kind !== SyntaxKind.BinaryExpression) { + const skipBindingPatterns = every(signature.typeParameters, p => !!getDefaultFromTypeParameter(p)); + const contextualType = getContextualType(node, skipBindingPatterns ? ContextFlags.SkipBindingPatterns : ContextFlags.None); + if (contextualType) { + const inferenceTargetType = getReturnTypeOfSignature(signature); + if (couldContainTypeVariables(inferenceTargetType)) { + const outerContext = getInferenceContext(node); + const isFromBindingPattern = !skipBindingPatterns && getContextualType(node, ContextFlags.SkipBindingPatterns) !== contextualType; + // A return type inference from a binding pattern can be used in instantiating the contextual + // type of an argument later in inference, but cannot stand on its own as the final return type. + // It is incorporated into `context.returnMapper` which is used in `instantiateContextualType`, + // but doesn't need to go into `context.inferences`. This allows a an array binding pattern to + // produce a tuple for `T` in + // declare function f(cb: () => T): T; + // const [e1, e2, e3] = f(() => [1, "hi", true]); + // but does not produce any inference for `T` in + // declare function f(): T; + // const [e1, e2, e3] = f(); + if (!isFromBindingPattern) { + // We clone the inference context to avoid disturbing a resolution in progress for an + // outer call expression. Effectively we just want a snapshot of whatever has been + // inferred for any outer call expression so far. + const outerMapper = getMapperFromContext(cloneInferenceContext(outerContext, InferenceFlags.NoDefault)); + const instantiatedType = instantiateType(contextualType, outerMapper); + // If the contextual type is a generic function type with a single call signature, we + // instantiate the type with its own type parameters and type arguments. This ensures that + // the type parameters are not erased to type any during type inference such that they can + // be inferred as actual types from the contextual type. For example: + // declare function arrayMap(f: (x: T) => U): (a: T[]) => U[]; + // const boxElements: (a: A[]) => { value: A }[] = arrayMap(value => ({ value })); + // Above, the type of the 'value' parameter is inferred to be 'A'. + const contextualSignature = getSingleCallSignature(instantiatedType); + const inferenceSourceType = contextualSignature && contextualSignature.typeParameters ? + getOrCreateTypeFromSignature(getSignatureInstantiationWithoutFillingInTypeArguments(contextualSignature, contextualSignature.typeParameters)) : + instantiatedType; + // Inferences made from return types have lower priority than all other inferences. + inferTypes(context.inferences, inferenceSourceType, inferenceTargetType, InferencePriority.ReturnType); + } + // Create a type mapper for instantiating generic contextual types using the inferences made + // from the return type. We need a separate inference pass here because (a) instantiation of + // the source type uses the outer context's return mapper (which excludes inferences made from + // outer arguments), and (b) we don't want any further inferences going into this context. + const returnContext = createInferenceContext(signature.typeParameters!, signature, context.flags); + const returnSourceType = instantiateType(contextualType, outerContext && outerContext.returnMapper); + inferTypes(returnContext.inferences, returnSourceType, inferenceTargetType); + context.returnMapper = some(returnContext.inferences, hasInferenceCandidates) ? getMapperFromContext(cloneInferredPartOfContext(returnContext)) : undefined; + } + } + } + + const restType = getNonArrayRestType(signature); + const argCount = restType ? Math.min(getParameterCount(signature) - 1, args.length) : args.length; + if (restType && restType.flags & TypeFlags.TypeParameter) { + const info = find(context.inferences, info => info.typeParameter === restType); + if (info) { + info.impliedArity = findIndex(args, isSpreadArgument, argCount) < 0 ? args.length - argCount : undefined; + } + } + + const thisType = getThisTypeOfSignature(signature); + if (thisType && couldContainTypeVariables(thisType)) { + const thisArgumentNode = getThisArgumentOfCall(node); + inferTypes(context.inferences, getThisArgumentType(thisArgumentNode), thisType); + } + + for (let i = 0; i < argCount; i++) { + const arg = args[i]; + if (arg.kind !== SyntaxKind.OmittedExpression) { + const paramType = getTypeAtPosition(signature, i); + if (couldContainTypeVariables(paramType)) { + const argType = checkExpressionWithContextualType(arg, paramType, context, checkMode); + inferTypes(context.inferences, argType, paramType); + } + } + } + + if (restType && couldContainTypeVariables(restType)) { + const spreadType = getSpreadArgumentType(args, argCount, args.length, restType, context, checkMode); + inferTypes(context.inferences, spreadType, restType); + } + + return getInferredTypes(context); + } + + function getMutableArrayOrTupleType(type: Type) { + return type.flags & TypeFlags.Union ? mapType(type, getMutableArrayOrTupleType) : + type.flags & TypeFlags.Any || isMutableArrayOrTuple(getBaseConstraintOfType(type) || type) ? type : + isTupleType(type) ? createTupleType(getElementTypes(type), type.target.elementFlags, /*readonly*/ false, type.target.labeledElementDeclarations) : + createTupleType([type], [ElementFlags.Variadic]); + } + + function getSpreadArgumentType(args: readonly Expression[], index: number, argCount: number, restType: Type, context: InferenceContext | undefined, checkMode: CheckMode) { + const inConstContext = isConstTypeVariable(restType); + + if (index >= argCount - 1) { + const arg = args[argCount - 1]; + if (isSpreadArgument(arg)) { + // We are inferring from a spread expression in the last argument position, i.e. both the parameter + // and the argument are ...x forms. + const spreadType = arg.kind === SyntaxKind.SyntheticExpression ? (arg as SyntheticExpression).type : + checkExpressionWithContextualType((arg as SpreadElement).expression, restType, context, checkMode); + + if (isArrayLikeType(spreadType)) { + return getMutableArrayOrTupleType(spreadType); + } + + return createArrayType(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, arg.kind === SyntaxKind.SpreadElement ? (arg as SpreadElement).expression : arg), inConstContext); + } + } + const types = []; + const flags = []; + const names = []; + for (let i = index; i < argCount; i++) { + const arg = args[i]; + if (isSpreadArgument(arg)) { + const spreadType = arg.kind === SyntaxKind.SyntheticExpression ? (arg as SyntheticExpression).type : checkExpression((arg as SpreadElement).expression); + if (isArrayLikeType(spreadType)) { + types.push(spreadType); + flags.push(ElementFlags.Variadic); + } + else { + types.push(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, arg.kind === SyntaxKind.SpreadElement ? (arg as SpreadElement).expression : arg)); + flags.push(ElementFlags.Rest); + } + } + else { + const contextualType = isTupleType(restType) ? + getContextualTypeForElementExpression(restType, i - index, argCount - index) || unknownType : + getIndexedAccessType(restType, getNumberLiteralType(i - index), AccessFlags.Contextual); + const argType = checkExpressionWithContextualType(arg, contextualType, context, checkMode); + const hasPrimitiveContextualType = inConstContext || maybeTypeOfKind(contextualType, TypeFlags.Primitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping); + types.push(hasPrimitiveContextualType ? getRegularTypeOfLiteralType(argType) : getWidenedLiteralType(argType)); + flags.push(ElementFlags.Required); + } + if (arg.kind === SyntaxKind.SyntheticExpression && (arg as SyntheticExpression).tupleNameSource) { + names.push((arg as SyntheticExpression).tupleNameSource!); + } + else { + names.push(undefined); + } + } + return createTupleType(types, flags, inConstContext && !someType(restType, isMutableArrayLikeType), names); + } + + function checkTypeArguments(signature: Signature, typeArgumentNodes: readonly TypeNode[], reportErrors: boolean, headMessage?: DiagnosticMessage): Type[] | undefined { + const isJavascript = isInJSFile(signature.declaration); + const typeParameters = signature.typeParameters!; + const typeArgumentTypes = fillMissingTypeArguments(map(typeArgumentNodes, getTypeFromTypeNode), typeParameters, getMinTypeArgumentCount(typeParameters), isJavascript); + let mapper: TypeMapper | undefined; + for (let i = 0; i < typeArgumentNodes.length; i++) { + Debug.assert(typeParameters[i] !== undefined, "Should not call checkTypeArguments with too many type arguments"); + const constraint = getConstraintOfTypeParameter(typeParameters[i]); + if (constraint) { + const errorInfo = reportErrors && headMessage ? (() => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Type_0_does_not_satisfy_the_constraint_1)) : undefined; + const typeArgumentHeadMessage = headMessage || Diagnostics.Type_0_does_not_satisfy_the_constraint_1; + if (!mapper) { + mapper = createTypeMapper(typeParameters, typeArgumentTypes); + } + const typeArgument = typeArgumentTypes[i]; + if ( + !checkTypeAssignableTo( + typeArgument, + getTypeWithThisArgument(instantiateType(constraint, mapper), typeArgument), + reportErrors ? typeArgumentNodes[i] : undefined, + typeArgumentHeadMessage, + errorInfo, + ) + ) { + return undefined; + } + } + } + return typeArgumentTypes; + } + + function getJsxReferenceKind(node: JsxOpeningLikeElement): JsxReferenceKind { + if (isJsxIntrinsicTagName(node.tagName)) { + return JsxReferenceKind.Mixed; + } + const tagType = getApparentType(checkExpression(node.tagName)); + if (length(getSignaturesOfType(tagType, SignatureKind.Construct))) { + return JsxReferenceKind.Component; + } + if (length(getSignaturesOfType(tagType, SignatureKind.Call))) { + return JsxReferenceKind.Function; + } + return JsxReferenceKind.Mixed; + } + + /** + * Check if the given signature can possibly be a signature called by the JSX opening-like element. + * @param node a JSX opening-like element we are trying to figure its call signature + * @param signature a candidate signature we are trying whether it is a call signature + * @param relation a relationship to check parameter and argument type + */ + function checkApplicableSignatureForJsxOpeningLikeElement( + node: JsxOpeningLikeElement, + signature: Signature, + relation: Map, + checkMode: CheckMode, + reportErrors: boolean, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; }, + ) { + // Stateless function components can have maximum of three arguments: "props", "context", and "updater". + // However "context" and "updater" are implicit and can't be specify by users. Only the first parameter, props, + // can be specified by users through attributes property. + const paramType = getEffectiveFirstArgumentForJsxSignature(signature, node); + const attributesType = checkExpressionWithContextualType(node.attributes, paramType, /*inferenceContext*/ undefined, checkMode); + const checkAttributesType = checkMode & CheckMode.SkipContextSensitive ? getRegularTypeOfObjectLiteral(attributesType) : attributesType; + return checkTagNameDoesNotExpectTooManyArguments() && checkTypeRelatedToAndOptionallyElaborate( + checkAttributesType, + paramType, + relation, + reportErrors ? node.tagName : undefined, + node.attributes, + /*headMessage*/ undefined, + containingMessageChain, + errorOutputContainer, + ); + + function checkTagNameDoesNotExpectTooManyArguments(): boolean { + if (getJsxNamespaceContainerForImplicitImport(node)) { + return true; // factory is implicitly jsx/jsxdev - assume it fits the bill, since we don't strongly look for the jsx/jsxs/jsxDEV factory APIs anywhere else (at least not yet) + } + const tagType = (isJsxOpeningElement(node) || isJsxSelfClosingElement(node)) && !(isJsxIntrinsicTagName(node.tagName) || isJsxNamespacedName(node.tagName)) ? checkExpression(node.tagName) : undefined; + if (!tagType) { + return true; + } + const tagCallSignatures = getSignaturesOfType(tagType, SignatureKind.Call); + if (!length(tagCallSignatures)) { + return true; + } + const factory = getJsxFactoryEntity(node); + if (!factory) { + return true; + } + const factorySymbol = resolveEntityName(factory, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ false, node); + if (!factorySymbol) { + return true; + } + + const factoryType = getTypeOfSymbol(factorySymbol); + const callSignatures = getSignaturesOfType(factoryType, SignatureKind.Call); + if (!length(callSignatures)) { + return true; + } + + let hasFirstParamSignatures = false; + let maxParamCount = 0; + // Check that _some_ first parameter expects a FC-like thing, and that some overload of the SFC expects an acceptable number of arguments + for (const sig of callSignatures) { + const firstparam = getTypeAtPosition(sig, 0); + const signaturesOfParam = getSignaturesOfType(firstparam, SignatureKind.Call); + if (!length(signaturesOfParam)) continue; + for (const paramSig of signaturesOfParam) { + hasFirstParamSignatures = true; + if (hasEffectiveRestParameter(paramSig)) { + return true; // some signature has a rest param, so function components can have an arbitrary number of arguments + } + const paramCount = getParameterCount(paramSig); + if (paramCount > maxParamCount) { + maxParamCount = paramCount; + } + } + } + if (!hasFirstParamSignatures) { + // Not a single signature had a first parameter which expected a signature - for back compat, and + // to guard against generic factories which won't have signatures directly, do not error + return true; + } + let absoluteMinArgCount = Infinity; + for (const tagSig of tagCallSignatures) { + const tagRequiredArgCount = getMinArgumentCount(tagSig); + if (tagRequiredArgCount < absoluteMinArgCount) { + absoluteMinArgCount = tagRequiredArgCount; + } + } + if (absoluteMinArgCount <= maxParamCount) { + return true; // some signature accepts the number of arguments the function component provides + } + + if (reportErrors) { + const diag = createDiagnosticForNode(node.tagName, Diagnostics.Tag_0_expects_at_least_1_arguments_but_the_JSX_factory_2_provides_at_most_3, entityNameToString(node.tagName), absoluteMinArgCount, entityNameToString(factory), maxParamCount); + const tagNameDeclaration = getSymbolAtLocation(node.tagName)?.valueDeclaration; + if (tagNameDeclaration) { + addRelatedInfo(diag, createDiagnosticForNode(tagNameDeclaration, Diagnostics._0_is_declared_here, entityNameToString(node.tagName))); + } + if (errorOutputContainer && errorOutputContainer.skipLogging) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + if (!errorOutputContainer.skipLogging) { + diagnostics.add(diag); + } + } + return false; + } + } + + function getEffectiveCheckNode(argument: Expression): Expression { + argument = skipParentheses(argument); + return isSatisfiesExpression(argument) ? skipParentheses(argument.expression) : argument; + } + + function getSignatureApplicabilityError( + node: CallLikeExpression, + args: readonly Expression[], + signature: Signature, + relation: Map, + checkMode: CheckMode, + reportErrors: boolean, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + inferenceContext: InferenceContext | undefined, + ): readonly Diagnostic[] | undefined { + const errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } = { errors: undefined, skipLogging: true }; + if (isJsxOpeningLikeElement(node)) { + if (!checkApplicableSignatureForJsxOpeningLikeElement(node, signature, relation, checkMode, reportErrors, containingMessageChain, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "jsx should have errors when reporting errors"); + return errorOutputContainer.errors || emptyArray; + } + return undefined; + } + const thisType = getThisTypeOfSignature(signature); + if (thisType && thisType !== voidType && !(isNewExpression(node) || isCallExpression(node) && isSuperProperty(node.expression))) { + // If the called expression is not of the form `x.f` or `x["f"]`, then sourceType = voidType + // If the signature's 'this' type is voidType, then the check is skipped -- anything is compatible. + // If the expression is a new expression or super call expression, then the check is skipped. + const thisArgumentNode = getThisArgumentOfCall(node); + const thisArgumentType = getThisArgumentType(thisArgumentNode); + const errorNode = reportErrors ? (thisArgumentNode || node) : undefined; + const headMessage = Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1; + if (!checkTypeRelatedTo(thisArgumentType, thisType, relation, errorNode, headMessage, containingMessageChain, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "this parameter should have errors when reporting errors"); + return errorOutputContainer.errors || emptyArray; + } + } + const headMessage = Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1; + const restType = getNonArrayRestType(signature); + const argCount = restType ? Math.min(getParameterCount(signature) - 1, args.length) : args.length; + for (let i = 0; i < argCount; i++) { + const arg = args[i]; + if (arg.kind !== SyntaxKind.OmittedExpression) { + const paramType = getTypeAtPosition(signature, i); + const argType = checkExpressionWithContextualType(arg, paramType, /*inferenceContext*/ undefined, checkMode); + // If one or more arguments are still excluded (as indicated by CheckMode.SkipContextSensitive), + // we obtain the regular type of any object literal arguments because we may not have inferred complete + // parameter types yet and therefore excess property checks may yield false positives (see #17041). + const regularArgType = checkMode & CheckMode.SkipContextSensitive ? getRegularTypeOfObjectLiteral(argType) : argType; + // If this was inferred under a given inference context, we may need to instantiate the expression type to finish resolving + // the type variables in the expression. + const checkArgType = inferenceContext ? instantiateType(regularArgType, inferenceContext.nonFixingMapper) : regularArgType; + const effectiveCheckArgumentNode = getEffectiveCheckNode(arg); + if (!checkTypeRelatedToAndOptionallyElaborate(checkArgType, paramType, relation, reportErrors ? effectiveCheckArgumentNode : undefined, effectiveCheckArgumentNode, headMessage, containingMessageChain, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "parameter should have errors when reporting errors"); + maybeAddMissingAwaitInfo(arg, checkArgType, paramType); + return errorOutputContainer.errors || emptyArray; + } + } + } + if (restType) { + const spreadType = getSpreadArgumentType(args, argCount, args.length, restType, /*context*/ undefined, checkMode); + const restArgCount = args.length - argCount; + const errorNode = !reportErrors ? undefined : + restArgCount === 0 ? node : + restArgCount === 1 ? getEffectiveCheckNode(args[argCount]) : + setTextRangePosEnd(createSyntheticExpression(node, spreadType), args[argCount].pos, args[args.length - 1].end); + if (!checkTypeRelatedTo(spreadType, restType, relation, errorNode, headMessage, /*containingMessageChain*/ undefined, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "rest parameter should have errors when reporting errors"); + maybeAddMissingAwaitInfo(errorNode, spreadType, restType); + return errorOutputContainer.errors || emptyArray; + } + } + return undefined; + + function maybeAddMissingAwaitInfo(errorNode: Node | undefined, source: Type, target: Type) { + if (errorNode && reportErrors && errorOutputContainer.errors && errorOutputContainer.errors.length) { + // Bail if target is Promise-like---something else is wrong + if (getAwaitedTypeOfPromise(target)) { + return; + } + const awaitedTypeOfSource = getAwaitedTypeOfPromise(source); + if (awaitedTypeOfSource && isTypeRelatedTo(awaitedTypeOfSource, target, relation)) { + addRelatedInfo(errorOutputContainer.errors[0], createDiagnosticForNode(errorNode, Diagnostics.Did_you_forget_to_use_await)); + } + } + } + } + + /** + * Returns the this argument in calls like x.f(...) and x[f](...). Undefined otherwise. + */ + function getThisArgumentOfCall(node: CallLikeExpression): Expression | undefined { + if (node.kind === SyntaxKind.BinaryExpression) { + return node.right; + } + + const expression = node.kind === SyntaxKind.CallExpression ? node.expression : + node.kind === SyntaxKind.TaggedTemplateExpression ? node.tag : + node.kind === SyntaxKind.Decorator && !legacyDecorators ? node.expression : + undefined; + if (expression) { + const callee = skipOuterExpressions(expression); + if (isAccessExpression(callee)) { + return callee.expression; + } + } + } + + function createSyntheticExpression(parent: Node, type: Type, isSpread?: boolean, tupleNameSource?: ParameterDeclaration | NamedTupleMember) { + const result = parseNodeFactory.createSyntheticExpression(type, isSpread, tupleNameSource); + setTextRangeWorker(result, parent); + setParent(result, parent); + return result; + } + + /** + * Returns the effective arguments for an expression that works like a function invocation. + */ + function getEffectiveCallArguments(node: CallLikeExpression): readonly Expression[] { + if (node.kind === SyntaxKind.TaggedTemplateExpression) { + const template = node.template; + const args: Expression[] = [createSyntheticExpression(template, getGlobalTemplateStringsArrayType())]; + if (template.kind === SyntaxKind.TemplateExpression) { + forEach(template.templateSpans, span => { + args.push(span.expression); + }); + } + return args; + } + if (node.kind === SyntaxKind.Decorator) { + return getEffectiveDecoratorArguments(node); + } + if (node.kind === SyntaxKind.BinaryExpression) { + return [node.left]; + } + if (isJsxOpeningLikeElement(node)) { + return node.attributes.properties.length > 0 || (isJsxOpeningElement(node) && node.parent.children.length > 0) ? [node.attributes] : emptyArray; + } + const args = node.arguments || emptyArray; + const spreadIndex = getSpreadArgumentIndex(args); + if (spreadIndex >= 0) { + // Create synthetic arguments from spreads of tuple types. + const effectiveArgs = args.slice(0, spreadIndex); + for (let i = spreadIndex; i < args.length; i++) { + const arg = args[i]; + // We can call checkExpressionCached because spread expressions never have a contextual type. + const spreadType = arg.kind === SyntaxKind.SpreadElement && (flowLoopCount ? checkExpression((arg as SpreadElement).expression) : checkExpressionCached((arg as SpreadElement).expression)); + if (spreadType && isTupleType(spreadType)) { + forEach(getElementTypes(spreadType), (t, i) => { + const flags = spreadType.target.elementFlags[i]; + const syntheticArg = createSyntheticExpression(arg, flags & ElementFlags.Rest ? createArrayType(t) : t, !!(flags & ElementFlags.Variable), spreadType.target.labeledElementDeclarations?.[i]); + effectiveArgs.push(syntheticArg); + }); + } + else { + effectiveArgs.push(arg); + } + } + return effectiveArgs; + } + return args; + } + + /** + * Returns the synthetic argument list for a decorator invocation. + */ + function getEffectiveDecoratorArguments(node: Decorator): readonly Expression[] { + const expr = node.expression; + const signature = getDecoratorCallSignature(node); + if (signature) { + const args: Expression[] = []; + for (const param of signature.parameters) { + const type = getTypeOfSymbol(param); + args.push(createSyntheticExpression(expr, type)); + } + return args; + } + return Debug.fail(); + } + + /** + * Returns the argument count for a decorator node that works like a function invocation. + */ + function getDecoratorArgumentCount(node: Decorator, signature: Signature) { + return compilerOptions.experimentalDecorators ? + getLegacyDecoratorArgumentCount(node, signature) : + // Allow the runtime to oversupply arguments to an ES decorator as long as there's at least one parameter. + Math.min(Math.max(getParameterCount(signature), 1), 2); + } + + /** + * Returns the argument count for a decorator node that works like a function invocation. + */ + function getLegacyDecoratorArgumentCount(node: Decorator, signature: Signature) { + switch (node.parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + return 1; + case SyntaxKind.PropertyDeclaration: + return hasAccessorModifier(node.parent) ? 3 : 2; + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + // For decorators with only two parameters we supply only two arguments + return signature.parameters.length <= 2 ? 2 : 3; + case SyntaxKind.Parameter: + return 3; + default: + return Debug.fail(); + } + } + + function getDiagnosticSpanForCallNode(node: CallExpression) { + const sourceFile = getSourceFileOfNode(node); + const { start, length } = getErrorSpanForNode(sourceFile, isPropertyAccessExpression(node.expression) ? node.expression.name : node.expression); + return { start, length, sourceFile }; + } + + function getDiagnosticForCallNode(node: CallLikeExpression, message: DiagnosticMessage | DiagnosticMessageChain, ...args: DiagnosticArguments): DiagnosticWithLocation { + if (isCallExpression(node)) { + const { sourceFile, start, length } = getDiagnosticSpanForCallNode(node); + if ("message" in message) { // eslint-disable-line local/no-in-operator + return createFileDiagnostic(sourceFile, start, length, message, ...args); + } + return createDiagnosticForFileFromMessageChain(sourceFile, message); + } + else { + if ("message" in message) { // eslint-disable-line local/no-in-operator + return createDiagnosticForNode(node, message, ...args); + } + return createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node), node, message); + } + } + + function getErrorNodeForCallNode(callLike: CallLikeExpression): Node { + if (isCallOrNewExpression(callLike)) { + return isPropertyAccessExpression(callLike.expression) ? callLike.expression.name : callLike.expression; + } + if (isTaggedTemplateExpression(callLike)) { + return isPropertyAccessExpression(callLike.tag) ? callLike.tag.name : callLike.tag; + } + if (isJsxOpeningLikeElement(callLike)) { + return callLike.tagName; + } + return callLike; + } + + function isPromiseResolveArityError(node: CallLikeExpression) { + if (!isCallExpression(node) || !isIdentifier(node.expression)) return false; + + const symbol = resolveName(node.expression, node.expression.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + const decl = symbol?.valueDeclaration; + if (!decl || !isParameter(decl) || !isFunctionExpressionOrArrowFunction(decl.parent) || !isNewExpression(decl.parent.parent) || !isIdentifier(decl.parent.parent.expression)) { + return false; + } + + const globalPromiseSymbol = getGlobalPromiseConstructorSymbol(/*reportErrors*/ false); + if (!globalPromiseSymbol) return false; + + const constructorSymbol = getSymbolAtLocation(decl.parent.parent.expression, /*ignoreErrors*/ true); + return constructorSymbol === globalPromiseSymbol; + } + + function getArgumentArityError(node: CallLikeExpression, signatures: readonly Signature[], args: readonly Expression[], headMessage?: DiagnosticMessage) { + const spreadIndex = getSpreadArgumentIndex(args); + if (spreadIndex > -1) { + return createDiagnosticForNode(args[spreadIndex], Diagnostics.A_spread_argument_must_either_have_a_tuple_type_or_be_passed_to_a_rest_parameter); + } + let min = Number.POSITIVE_INFINITY; // smallest parameter count + let max = Number.NEGATIVE_INFINITY; // largest parameter count + let maxBelow = Number.NEGATIVE_INFINITY; // largest parameter count that is smaller than the number of arguments + let minAbove = Number.POSITIVE_INFINITY; // smallest parameter count that is larger than the number of arguments + + let closestSignature: Signature | undefined; + for (const sig of signatures) { + const minParameter = getMinArgumentCount(sig); + const maxParameter = getParameterCount(sig); + // smallest/largest parameter counts + if (minParameter < min) { + min = minParameter; + closestSignature = sig; + } + max = Math.max(max, maxParameter); + // shortest parameter count *longer than the call*/longest parameter count *shorter than the call* + if (minParameter < args.length && minParameter > maxBelow) maxBelow = minParameter; + if (args.length < maxParameter && maxParameter < minAbove) minAbove = maxParameter; + } + const hasRestParameter = some(signatures, hasEffectiveRestParameter); + const parameterRange = hasRestParameter ? min + : min < max ? min + "-" + max + : min; + const isVoidPromiseError = !hasRestParameter && parameterRange === 1 && args.length === 0 && isPromiseResolveArityError(node); + if (isVoidPromiseError && isInJSFile(node)) { + return getDiagnosticForCallNode(node, Diagnostics.Expected_1_argument_but_got_0_new_Promise_needs_a_JSDoc_hint_to_produce_a_resolve_that_can_be_called_without_arguments); + } + const error = isDecorator(node) ? + hasRestParameter ? Diagnostics.The_runtime_will_invoke_the_decorator_with_1_arguments_but_the_decorator_expects_at_least_0 : + Diagnostics.The_runtime_will_invoke_the_decorator_with_1_arguments_but_the_decorator_expects_0 : + hasRestParameter ? Diagnostics.Expected_at_least_0_arguments_but_got_1 : + isVoidPromiseError ? Diagnostics.Expected_0_arguments_but_got_1_Did_you_forget_to_include_void_in_your_type_argument_to_Promise : + Diagnostics.Expected_0_arguments_but_got_1; + + if (min < args.length && args.length < max) { + // between min and max, but with no matching overload + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_overload_expects_0_arguments_but_overloads_do_exist_that_expect_either_1_or_2_arguments, args.length, maxBelow, minAbove); + chain = chainDiagnosticMessages(chain, headMessage); + return getDiagnosticForCallNode(node, chain); + } + return getDiagnosticForCallNode(node, Diagnostics.No_overload_expects_0_arguments_but_overloads_do_exist_that_expect_either_1_or_2_arguments, args.length, maxBelow, minAbove); + } + else if (args.length < min) { + // too short: put the error span on the call expression, not any of the args + let diagnostic: Diagnostic; + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, error, parameterRange, args.length); + chain = chainDiagnosticMessages(chain, headMessage); + diagnostic = getDiagnosticForCallNode(node, chain); + } + else { + diagnostic = getDiagnosticForCallNode(node, error, parameterRange, args.length); + } + const parameter = closestSignature?.declaration?.parameters[closestSignature.thisParameter ? args.length + 1 : args.length]; + if (parameter) { + const messageAndArgs: DiagnosticAndArguments = isBindingPattern(parameter.name) ? [Diagnostics.An_argument_matching_this_binding_pattern_was_not_provided] + : isRestParameter(parameter) ? [Diagnostics.Arguments_for_the_rest_parameter_0_were_not_provided, idText(getFirstIdentifier(parameter.name))] + : [Diagnostics.An_argument_for_0_was_not_provided, !parameter.name ? args.length : idText(getFirstIdentifier(parameter.name))]; + const parameterError = createDiagnosticForNode(parameter, ...messageAndArgs); + return addRelatedInfo(diagnostic, parameterError); + } + return diagnostic; + } + else { + // too long; error goes on the excess parameters + const errorSpan = factory.createNodeArray(args.slice(max)); + const pos = first(errorSpan).pos; + let end = last(errorSpan).end; + if (end === pos) { + end++; + } + setTextRangePosEnd(errorSpan, pos, end); + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, error, parameterRange, args.length); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), errorSpan, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), errorSpan, error, parameterRange, args.length); + } + } + + function getTypeArgumentArityError(node: Node, signatures: readonly Signature[], typeArguments: NodeArray, headMessage?: DiagnosticMessage) { + const argCount = typeArguments.length; + // No overloads exist + if (signatures.length === 1) { + const sig = signatures[0]; + const min = getMinTypeArgumentCount(sig.typeParameters); + const max = length(sig.typeParameters); + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Expected_0_type_arguments_but_got_1, min < max ? min + "-" + max : min, argCount); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Expected_0_type_arguments_but_got_1, min < max ? min + "-" + max : min, argCount); + } + // Overloads exist + let belowArgCount = -Infinity; + let aboveArgCount = Infinity; + for (const sig of signatures) { + const min = getMinTypeArgumentCount(sig.typeParameters); + const max = length(sig.typeParameters); + if (min > argCount) { + aboveArgCount = Math.min(aboveArgCount, min); + } + else if (max < argCount) { + belowArgCount = Math.max(belowArgCount, max); + } + } + if (belowArgCount !== -Infinity && aboveArgCount !== Infinity) { + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_overload_expects_0_type_arguments_but_overloads_do_exist_that_expect_either_1_or_2_type_arguments, argCount, belowArgCount, aboveArgCount); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.No_overload_expects_0_type_arguments_but_overloads_do_exist_that_expect_either_1_or_2_type_arguments, argCount, belowArgCount, aboveArgCount); + } + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Expected_0_type_arguments_but_got_1, belowArgCount === -Infinity ? aboveArgCount : belowArgCount, argCount); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Expected_0_type_arguments_but_got_1, belowArgCount === -Infinity ? aboveArgCount : belowArgCount, argCount); + } + + function resolveCall(node: CallLikeExpression, signatures: readonly Signature[], candidatesOutArray: Signature[] | undefined, checkMode: CheckMode, callChainFlags: SignatureFlags, headMessage?: DiagnosticMessage): Signature { + const isTaggedTemplate = node.kind === SyntaxKind.TaggedTemplateExpression; + const isDecorator = node.kind === SyntaxKind.Decorator; + const isJsxOpeningOrSelfClosingElement = isJsxOpeningLikeElement(node); + const isInstanceof = node.kind === SyntaxKind.BinaryExpression; + const reportErrors = !isInferencePartiallyBlocked && !candidatesOutArray; + + let typeArguments: NodeArray | undefined; + + if (!isDecorator && !isInstanceof && !isSuperCall(node)) { + typeArguments = (node as CallExpression).typeArguments; + + // We already perform checking on the type arguments on the class declaration itself. + if (isTaggedTemplate || isJsxOpeningOrSelfClosingElement || (node as CallExpression).expression.kind !== SyntaxKind.SuperKeyword) { + forEach(typeArguments, checkSourceElement); + } + } + + const candidates = candidatesOutArray || []; + // reorderCandidates fills up the candidates array directly + reorderCandidates(signatures, candidates, callChainFlags); + Debug.assert(candidates.length, "Revert #54442 and add a testcase with whatever triggered this"); + + const args = getEffectiveCallArguments(node); + + // The excludeArgument array contains true for each context sensitive argument (an argument + // is context sensitive it is susceptible to a one-time permanent contextual typing). + // + // The idea is that we will perform type argument inference & assignability checking once + // without using the susceptible parameters that are functions, and once more for those + // parameters, contextually typing each as we go along. + // + // For a tagged template, then the first argument be 'undefined' if necessary because it + // represents a TemplateStringsArray. + // + // For a decorator, no arguments are susceptible to contextual typing due to the fact + // decorators are applied to a declaration by the emitter, and not to an expression. + const isSingleNonGenericCandidate = candidates.length === 1 && !candidates[0].typeParameters; + let argCheckMode = !isDecorator && !isSingleNonGenericCandidate && some(args, isContextSensitive) ? CheckMode.SkipContextSensitive : CheckMode.Normal; + + // The following variables are captured and modified by calls to chooseOverload. + // If overload resolution or type argument inference fails, we want to report the + // best error possible. The best error is one which says that an argument was not + // assignable to a parameter. This implies that everything else about the overload + // was fine. So if there is any overload that is only incorrect because of an + // argument, we will report an error on that one. + // + // function foo(s: string): void; + // function foo(n: number): void; // Report argument error on this overload + // function foo(): void; + // foo(true); + // + // If none of the overloads even made it that far, there are two possibilities. + // There was a problem with type arguments for some overload, in which case + // report an error on that. Or none of the overloads even had correct arity, + // in which case give an arity error. + // + // function foo(x: T): void; // Report type argument error + // function foo(): void; + // foo(0); + // + let candidatesForArgumentError: Signature[] | undefined; + let candidateForArgumentArityError: Signature | undefined; + let candidateForTypeArgumentError: Signature | undefined; + let result: Signature | undefined; + + // If we are in signature help, a trailing comma indicates that we intend to provide another argument, + // so we will only accept overloads with arity at least 1 higher than the current number of provided arguments. + const signatureHelpTrailingComma = !!(checkMode & CheckMode.IsForSignatureHelp) && node.kind === SyntaxKind.CallExpression && node.arguments.hasTrailingComma; + + // Section 4.12.1: + // if the candidate list contains one or more signatures for which the type of each argument + // expression is a subtype of each corresponding parameter type, the return type of the first + // of those signatures becomes the return type of the function call. + // Otherwise, the return type of the first signature in the candidate list becomes the return + // type of the function call. + // + // Whether the call is an error is determined by assignability of the arguments. The subtype pass + // is just important for choosing the best signature. So in the case where there is only one + // signature, the subtype pass is useless. So skipping it is an optimization. + if (candidates.length > 1) { + result = chooseOverload(candidates, subtypeRelation, isSingleNonGenericCandidate, signatureHelpTrailingComma); + } + if (!result) { + result = chooseOverload(candidates, assignableRelation, isSingleNonGenericCandidate, signatureHelpTrailingComma); + } + if (result) { + return result; + } + + result = getCandidateForOverloadFailure(node, candidates, args, !!candidatesOutArray, checkMode); + // Preemptively cache the result; getResolvedSignature will do this after we return, but + // we need to ensure that the result is present for the error checks below so that if + // this signature is encountered again, we handle the circularity (rather than producing a + // different result which may produce no errors and assert). Callers of getResolvedSignature + // don't hit this issue because they only observe this result after it's had a chance to + // be cached, but the error reporting code below executes before getResolvedSignature sets + // resolvedSignature. + getNodeLinks(node).resolvedSignature = result; + + // No signatures were applicable. Now report errors based on the last applicable signature with + // no arguments excluded from assignability checks. + // If candidate is undefined, it means that no candidates had a suitable arity. In that case, + // skip the checkApplicableSignature check. + if (reportErrors) { + // If the call expression is a synthetic call to a `[Symbol.hasInstance]` method then we will produce a head + // message when reporting diagnostics that explains how we got to `right[Symbol.hasInstance](left)` from + // `left instanceof right`, as it pertains to "Argument" related messages reported for the call. + if (!headMessage && isInstanceof) { + headMessage = Diagnostics.The_left_hand_side_of_an_instanceof_expression_must_be_assignable_to_the_first_argument_of_the_right_hand_side_s_Symbol_hasInstance_method; + } + if (candidatesForArgumentError) { + if (candidatesForArgumentError.length === 1 || candidatesForArgumentError.length > 3) { + const last = candidatesForArgumentError[candidatesForArgumentError.length - 1]; + let chain: DiagnosticMessageChain | undefined; + if (candidatesForArgumentError.length > 3) { + chain = chainDiagnosticMessages(chain, Diagnostics.The_last_overload_gave_the_following_error); + chain = chainDiagnosticMessages(chain, Diagnostics.No_overload_matches_this_call); + } + if (headMessage) { + chain = chainDiagnosticMessages(chain, headMessage); + } + const diags = getSignatureApplicabilityError(node, args, last, assignableRelation, CheckMode.Normal, /*reportErrors*/ true, () => chain, /*inferenceContext*/ undefined); + if (diags) { + for (const d of diags) { + if (last.declaration && candidatesForArgumentError.length > 3) { + addRelatedInfo(d, createDiagnosticForNode(last.declaration, Diagnostics.The_last_overload_is_declared_here)); + } + addImplementationSuccessElaboration(last, d); + diagnostics.add(d); + } + } + else { + Debug.fail("No error for last overload signature"); + } + } + else { + const allDiagnostics: (readonly DiagnosticRelatedInformation[])[] = []; + let max = 0; + let min = Number.MAX_VALUE; + let minIndex = 0; + let i = 0; + for (const c of candidatesForArgumentError) { + const chain = () => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Overload_0_of_1_2_gave_the_following_error, i + 1, candidates.length, signatureToString(c)); + const diags = getSignatureApplicabilityError(node, args, c, assignableRelation, CheckMode.Normal, /*reportErrors*/ true, chain, /*inferenceContext*/ undefined); + if (diags) { + if (diags.length <= min) { + min = diags.length; + minIndex = i; + } + max = Math.max(max, diags.length); + allDiagnostics.push(diags); + } + else { + Debug.fail("No error for 3 or fewer overload signatures"); + } + i++; + } + + const diags = max > 1 ? allDiagnostics[minIndex] : flatten(allDiagnostics); + Debug.assert(diags.length > 0, "No errors reported for 3 or fewer overload signatures"); + let chain = chainDiagnosticMessages( + map(diags, createDiagnosticMessageChainFromDiagnostic), + Diagnostics.No_overload_matches_this_call, + ); + if (headMessage) { + chain = chainDiagnosticMessages(chain, headMessage); + } + // The below is a spread to guarantee we get a new (mutable) array - our `flatMap` helper tries to do "smart" optimizations where it reuses input + // arrays and the emptyArray singleton where possible, which is decidedly not what we want while we're still constructing this diagnostic + const related = [...flatMap(diags, d => (d as Diagnostic).relatedInformation) as DiagnosticRelatedInformation[]]; + let diag: Diagnostic; + if (every(diags, d => d.start === diags[0].start && d.length === diags[0].length && d.file === diags[0].file)) { + const { file, start, length } = diags[0]; + diag = { file, start, length, code: chain.code, category: chain.category, messageText: chain, relatedInformation: related }; + } + else { + diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node), getErrorNodeForCallNode(node), chain, related); + } + addImplementationSuccessElaboration(candidatesForArgumentError[0], diag); + diagnostics.add(diag); + } + } + else if (candidateForArgumentArityError) { + diagnostics.add(getArgumentArityError(node, [candidateForArgumentArityError], args, headMessage)); + } + else if (candidateForTypeArgumentError) { + checkTypeArguments(candidateForTypeArgumentError, (node as CallExpression | TaggedTemplateExpression | JsxOpeningLikeElement).typeArguments!, /*reportErrors*/ true, headMessage); + } + else { + const signaturesWithCorrectTypeArgumentArity = filter(signatures, s => hasCorrectTypeArgumentArity(s, typeArguments)); + if (signaturesWithCorrectTypeArgumentArity.length === 0) { + diagnostics.add(getTypeArgumentArityError(node, signatures, typeArguments!, headMessage)); + } + else { + diagnostics.add(getArgumentArityError(node, signaturesWithCorrectTypeArgumentArity, args, headMessage)); + } + } + } + + return result; + + function addImplementationSuccessElaboration(failed: Signature, diagnostic: Diagnostic) { + const oldCandidatesForArgumentError = candidatesForArgumentError; + const oldCandidateForArgumentArityError = candidateForArgumentArityError; + const oldCandidateForTypeArgumentError = candidateForTypeArgumentError; + + const failedSignatureDeclarations = failed.declaration?.symbol?.declarations || emptyArray; + const isOverload = failedSignatureDeclarations.length > 1; + const implDecl = isOverload ? find(failedSignatureDeclarations, d => isFunctionLikeDeclaration(d) && nodeIsPresent(d.body)) : undefined; + if (implDecl) { + const candidate = getSignatureFromDeclaration(implDecl as FunctionLikeDeclaration); + const isSingleNonGenericCandidate = !candidate.typeParameters; + if (chooseOverload([candidate], assignableRelation, isSingleNonGenericCandidate)) { + addRelatedInfo(diagnostic, createDiagnosticForNode(implDecl, Diagnostics.The_call_would_have_succeeded_against_this_implementation_but_implementation_signatures_of_overloads_are_not_externally_visible)); + } + } + + candidatesForArgumentError = oldCandidatesForArgumentError; + candidateForArgumentArityError = oldCandidateForArgumentArityError; + candidateForTypeArgumentError = oldCandidateForTypeArgumentError; + } + + function chooseOverload(candidates: Signature[], relation: Map, isSingleNonGenericCandidate: boolean, signatureHelpTrailingComma = false) { + candidatesForArgumentError = undefined; + candidateForArgumentArityError = undefined; + candidateForTypeArgumentError = undefined; + + if (isSingleNonGenericCandidate) { + const candidate = candidates[0]; + if (some(typeArguments) || !hasCorrectArity(node, args, candidate, signatureHelpTrailingComma)) { + return undefined; + } + if (getSignatureApplicabilityError(node, args, candidate, relation, CheckMode.Normal, /*reportErrors*/ false, /*containingMessageChain*/ undefined, /*inferenceContext*/ undefined)) { + candidatesForArgumentError = [candidate]; + return undefined; + } + return candidate; + } + + for (let candidateIndex = 0; candidateIndex < candidates.length; candidateIndex++) { + let candidate = candidates[candidateIndex]; + if (!hasCorrectTypeArgumentArity(candidate, typeArguments) || !hasCorrectArity(node, args, candidate, signatureHelpTrailingComma)) { + continue; + } + + let checkCandidate: Signature; + let inferenceContext: InferenceContext | undefined; + + if (candidate.typeParameters) { + // If we are *inside the body of candidate*, we need to create a clone of `candidate` with differing type parameter identities, + // so our inference results for this call doesn't pollute expression types referencing the outer type parameter! + const paramLocation = candidate.typeParameters[0].symbol.declarations?.[0]?.parent; + const candidateParameterContext = paramLocation || (candidate.declaration && isConstructorDeclaration(candidate.declaration) ? candidate.declaration.parent : candidate.declaration); + if (candidateParameterContext && findAncestor(node, a => a === candidateParameterContext)) { + candidate = getImplementationSignature(candidate); + } + let typeArgumentTypes: readonly Type[] | undefined; + if (some(typeArguments)) { + typeArgumentTypes = checkTypeArguments(candidate, typeArguments, /*reportErrors*/ false); + if (!typeArgumentTypes) { + candidateForTypeArgumentError = candidate; + continue; + } + } + else { + inferenceContext = createInferenceContext(candidate.typeParameters!, candidate, /*flags*/ isInJSFile(node) ? InferenceFlags.AnyDefault : InferenceFlags.None); + // The resulting type arguments are instantiated with the inference context mapper, as the inferred types may still contain references to the inference context's + // type variables via contextual projection. These are kept generic until all inferences are locked in, so the dependencies expressed can pass constraint checks. + typeArgumentTypes = instantiateTypes(inferTypeArguments(node, candidate, args, argCheckMode | CheckMode.SkipGenericFunctions, inferenceContext), inferenceContext.nonFixingMapper); + argCheckMode |= inferenceContext.flags & InferenceFlags.SkippedGenericFunction ? CheckMode.SkipGenericFunctions : CheckMode.Normal; + } + checkCandidate = getSignatureInstantiation(candidate, typeArgumentTypes, isInJSFile(candidate.declaration), inferenceContext && inferenceContext.inferredTypeParameters); + // If the original signature has a generic rest type, instantiation may produce a + // signature with different arity and we need to perform another arity check. + if (getNonArrayRestType(candidate) && !hasCorrectArity(node, args, checkCandidate, signatureHelpTrailingComma)) { + candidateForArgumentArityError = checkCandidate; + continue; + } + } + else { + checkCandidate = candidate; + } + if (getSignatureApplicabilityError(node, args, checkCandidate, relation, argCheckMode, /*reportErrors*/ false, /*containingMessageChain*/ undefined, inferenceContext)) { + // Give preference to error candidates that have no rest parameters (as they are more specific) + (candidatesForArgumentError || (candidatesForArgumentError = [])).push(checkCandidate); + continue; + } + if (argCheckMode) { + // If one or more context sensitive arguments were excluded, we start including + // them now (and keeping do so for any subsequent candidates) and perform a second + // round of type inference and applicability checking for this particular candidate. + argCheckMode = CheckMode.Normal; + if (inferenceContext) { + const typeArgumentTypes = instantiateTypes(inferTypeArguments(node, candidate, args, argCheckMode, inferenceContext), inferenceContext.mapper); + checkCandidate = getSignatureInstantiation(candidate, typeArgumentTypes, isInJSFile(candidate.declaration), inferenceContext.inferredTypeParameters); + // If the original signature has a generic rest type, instantiation may produce a + // signature with different arity and we need to perform another arity check. + if (getNonArrayRestType(candidate) && !hasCorrectArity(node, args, checkCandidate, signatureHelpTrailingComma)) { + candidateForArgumentArityError = checkCandidate; + continue; + } + } + if (getSignatureApplicabilityError(node, args, checkCandidate, relation, argCheckMode, /*reportErrors*/ false, /*containingMessageChain*/ undefined, inferenceContext)) { + // Give preference to error candidates that have no rest parameters (as they are more specific) + (candidatesForArgumentError || (candidatesForArgumentError = [])).push(checkCandidate); + continue; + } + } + candidates[candidateIndex] = checkCandidate; + return checkCandidate; + } + + return undefined; + } + } + + // No signature was applicable. We have already reported the errors for the invalid signature. + function getCandidateForOverloadFailure( + node: CallLikeExpression, + candidates: Signature[], + args: readonly Expression[], + hasCandidatesOutArray: boolean, + checkMode: CheckMode, + ): Signature { + Debug.assert(candidates.length > 0); // Else should not have called this. + checkNodeDeferred(node); + // Normally we will combine overloads. Skip this if they have type parameters since that's hard to combine. + // Don't do this if there is a `candidatesOutArray`, + // because then we want the chosen best candidate to be one of the overloads, not a combination. + return hasCandidatesOutArray || candidates.length === 1 || candidates.some(c => !!c.typeParameters) + ? pickLongestCandidateSignature(node, candidates, args, checkMode) + : createUnionOfSignaturesForOverloadFailure(candidates); + } + + function createUnionOfSignaturesForOverloadFailure(candidates: readonly Signature[]): Signature { + const thisParameters = mapDefined(candidates, c => c.thisParameter); + let thisParameter: Symbol | undefined; + if (thisParameters.length) { + thisParameter = createCombinedSymbolFromTypes(thisParameters, thisParameters.map(getTypeOfParameter)); + } + const { min: minArgumentCount, max: maxNonRestParam } = minAndMax(candidates, getNumNonRestParameters); + const parameters: Symbol[] = []; + for (let i = 0; i < maxNonRestParam; i++) { + const symbols = mapDefined(candidates, s => + signatureHasRestParameter(s) ? + i < s.parameters.length - 1 ? s.parameters[i] : last(s.parameters) : + i < s.parameters.length ? s.parameters[i] : undefined); + Debug.assert(symbols.length !== 0); + parameters.push(createCombinedSymbolFromTypes(symbols, mapDefined(candidates, candidate => tryGetTypeAtPosition(candidate, i)))); + } + const restParameterSymbols = mapDefined(candidates, c => signatureHasRestParameter(c) ? last(c.parameters) : undefined); + let flags = SignatureFlags.IsSignatureCandidateForOverloadFailure; + if (restParameterSymbols.length !== 0) { + const type = createArrayType(getUnionType(mapDefined(candidates, tryGetRestTypeOfSignature), UnionReduction.Subtype)); + parameters.push(createCombinedSymbolForOverloadFailure(restParameterSymbols, type)); + flags |= SignatureFlags.HasRestParameter; + } + if (candidates.some(signatureHasLiteralTypes)) { + flags |= SignatureFlags.HasLiteralTypes; + } + return createSignature( + candidates[0].declaration, + /*typeParameters*/ undefined, // Before calling this we tested for `!candidates.some(c => !!c.typeParameters)`. + thisParameter, + parameters, + /*resolvedReturnType*/ getIntersectionType(candidates.map(getReturnTypeOfSignature)), + /*resolvedTypePredicate*/ undefined, + minArgumentCount, + flags, + ); + } + + function getNumNonRestParameters(signature: Signature): number { + const numParams = signature.parameters.length; + return signatureHasRestParameter(signature) ? numParams - 1 : numParams; + } + + function createCombinedSymbolFromTypes(sources: readonly Symbol[], types: Type[]): Symbol { + return createCombinedSymbolForOverloadFailure(sources, getUnionType(types, UnionReduction.Subtype)); + } + + function createCombinedSymbolForOverloadFailure(sources: readonly Symbol[], type: Type): Symbol { + // This function is currently only used for erroneous overloads, so it's good enough to just use the first source. + return createSymbolWithType(first(sources), type); + } + + function pickLongestCandidateSignature(node: CallLikeExpression, candidates: Signature[], args: readonly Expression[], checkMode: CheckMode): Signature { + // Pick the longest signature. This way we can get a contextual type for cases like: + // declare function f(a: { xa: number; xb: number; }, b: number); + // f({ | + // Also, use explicitly-supplied type arguments if they are provided, so we can get a contextual signature in cases like: + // declare function f(k: keyof T); + // f(" + const bestIndex = getLongestCandidateIndex(candidates, apparentArgumentCount === undefined ? args.length : apparentArgumentCount); + const candidate = candidates[bestIndex]; + const { typeParameters } = candidate; + if (!typeParameters) { + return candidate; + } + + const typeArgumentNodes: readonly TypeNode[] | undefined = callLikeExpressionMayHaveTypeArguments(node) ? node.typeArguments : undefined; + const instantiated = typeArgumentNodes + ? createSignatureInstantiation(candidate, getTypeArgumentsFromNodes(typeArgumentNodes, typeParameters, isInJSFile(node))) + : inferSignatureInstantiationForOverloadFailure(node, typeParameters, candidate, args, checkMode); + candidates[bestIndex] = instantiated; + return instantiated; + } + + function getTypeArgumentsFromNodes(typeArgumentNodes: readonly TypeNode[], typeParameters: readonly TypeParameter[], isJs: boolean): readonly Type[] { + const typeArguments = typeArgumentNodes.map(getTypeOfNode); + while (typeArguments.length > typeParameters.length) { + typeArguments.pop(); + } + while (typeArguments.length < typeParameters.length) { + typeArguments.push(getDefaultFromTypeParameter(typeParameters[typeArguments.length]) || getConstraintOfTypeParameter(typeParameters[typeArguments.length]) || getDefaultTypeArgumentType(isJs)); + } + return typeArguments; + } + + function inferSignatureInstantiationForOverloadFailure(node: CallLikeExpression, typeParameters: readonly TypeParameter[], candidate: Signature, args: readonly Expression[], checkMode: CheckMode): Signature { + const inferenceContext = createInferenceContext(typeParameters, candidate, /*flags*/ isInJSFile(node) ? InferenceFlags.AnyDefault : InferenceFlags.None); + const typeArgumentTypes = inferTypeArguments(node, candidate, args, checkMode | CheckMode.SkipContextSensitive | CheckMode.SkipGenericFunctions, inferenceContext); + return createSignatureInstantiation(candidate, typeArgumentTypes); + } + + function getLongestCandidateIndex(candidates: Signature[], argsCount: number): number { + let maxParamsIndex = -1; + let maxParams = -1; + + for (let i = 0; i < candidates.length; i++) { + const candidate = candidates[i]; + const paramCount = getParameterCount(candidate); + if (hasEffectiveRestParameter(candidate) || paramCount >= argsCount) { + return i; + } + if (paramCount > maxParams) { + maxParams = paramCount; + maxParamsIndex = i; + } + } + + return maxParamsIndex; + } + + function resolveCallExpression(node: CallExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + if (node.expression.kind === SyntaxKind.SuperKeyword) { + const superType = checkSuperExpression(node.expression); + if (isTypeAny(superType)) { + for (const arg of node.arguments) { + checkExpression(arg); // Still visit arguments so they get marked for visibility, etc + } + return anySignature; + } + if (!isErrorType(superType)) { + // In super call, the candidate signatures are the matching arity signatures of the base constructor function instantiated + // with the type arguments specified in the extends clause. + const baseTypeNode = getEffectiveBaseTypeNode(getContainingClass(node)!); + if (baseTypeNode) { + const baseConstructors = getInstantiatedConstructorsForTypeArguments(superType, baseTypeNode.typeArguments, baseTypeNode); + return resolveCall(node, baseConstructors, candidatesOutArray, checkMode, SignatureFlags.None); + } + } + return resolveUntypedCall(node); + } + + let callChainFlags: SignatureFlags; + let funcType = checkExpression(node.expression); + if (isCallChain(node)) { + const nonOptionalType = getOptionalExpressionType(funcType, node.expression); + callChainFlags = nonOptionalType === funcType ? SignatureFlags.None : + isOutermostOptionalChain(node) ? SignatureFlags.IsOuterCallChain : + SignatureFlags.IsInnerCallChain; + funcType = nonOptionalType; + } + else { + callChainFlags = SignatureFlags.None; + } + + funcType = checkNonNullTypeWithReporter( + funcType, + node.expression, + reportCannotInvokePossiblyNullOrUndefinedError, + ); + + if (funcType === silentNeverType) { + return silentNeverSignature; + } + + const apparentType = getApparentType(funcType); + if (isErrorType(apparentType)) { + // Another error has already been reported + return resolveErrorCall(node); + } + + // Technically, this signatures list may be incomplete. We are taking the apparent type, + // but we are not including call signatures that may have been added to the Object or + // Function interface, since they have none by default. This is a bit of a leap of faith + // that the user will not add any. + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; + + // TS 1.0 Spec: 4.12 + // In an untyped function call no TypeArgs are permitted, Args can be any argument list, no contextual + // types are provided for the argument expressions, and the result is always of type Any. + if (isUntypedFunctionCall(funcType, apparentType, callSignatures.length, numConstructSignatures)) { + // The unknownType indicates that an error already occurred (and was reported). No + // need to report another error in this case. + if (!isErrorType(funcType) && node.typeArguments) { + error(node, Diagnostics.Untyped_function_calls_may_not_accept_type_arguments); + } + return resolveUntypedCall(node); + } + // If FuncExpr's apparent type(section 3.8.1) is a function type, the call is a typed function call. + // TypeScript employs overload resolution in typed function calls in order to support functions + // with multiple call signatures. + if (!callSignatures.length) { + if (numConstructSignatures) { + error(node, Diagnostics.Value_of_type_0_is_not_callable_Did_you_mean_to_include_new, typeToString(funcType)); + } + else { + let relatedInformation: DiagnosticRelatedInformation | undefined; + if (node.arguments.length === 1) { + const text = getSourceFileOfNode(node).text; + if (isLineBreak(text.charCodeAt(skipTrivia(text, node.expression.end, /*stopAfterLineBreak*/ true) - 1))) { + relatedInformation = createDiagnosticForNode(node.expression, Diagnostics.Are_you_missing_a_semicolon); + } + } + invocationError(node.expression, apparentType, SignatureKind.Call, relatedInformation); + } + return resolveErrorCall(node); + } + // When a call to a generic function is an argument to an outer call to a generic function for which + // inference is in process, we have a choice to make. If the inner call relies on inferences made from + // its contextual type to its return type, deferring the inner call processing allows the best possible + // contextual type to accumulate. But if the outer call relies on inferences made from the return type of + // the inner call, the inner call should be processed early. There's no sure way to know which choice is + // right (only a full unification algorithm can determine that), so we resort to the following heuristic: + // If no type arguments are specified in the inner call and at least one call signature is generic and + // returns a function type, we choose to defer processing. This narrowly permits function composition + // operators to flow inferences through return types, but otherwise processes calls right away. We + // use the resolvingSignature singleton to indicate that we deferred processing. This result will be + // propagated out and eventually turned into silentNeverType (a type that is assignable to anything and + // from which we never make inferences). + if (checkMode & CheckMode.SkipGenericFunctions && !node.typeArguments && callSignatures.some(isGenericFunctionReturningFunction)) { + skippedGenericFunction(node, checkMode); + return resolvingSignature; + } + // If the function is explicitly marked with `@class`, then it must be constructed. + if (callSignatures.some(sig => isInJSFile(sig.declaration) && !!getJSDocClassTag(sig.declaration!))) { + error(node, Diagnostics.Value_of_type_0_is_not_callable_Did_you_mean_to_include_new, typeToString(funcType)); + return resolveErrorCall(node); + } + + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, callChainFlags); + } + + function isGenericFunctionReturningFunction(signature: Signature) { + return !!(signature.typeParameters && isFunctionType(getReturnTypeOfSignature(signature))); + } + + /** + * TS 1.0 spec: 4.12 + * If FuncExpr is of type Any, or of an object type that has no call or construct signatures + * but is a subtype of the Function interface, the call is an untyped function call. + */ + function isUntypedFunctionCall(funcType: Type, apparentFuncType: Type, numCallSignatures: number, numConstructSignatures: number): boolean { + // We exclude union types because we may have a union of function types that happen to have no common signatures. + return isTypeAny(funcType) || isTypeAny(apparentFuncType) && !!(funcType.flags & TypeFlags.TypeParameter) || + !numCallSignatures && !numConstructSignatures && !(apparentFuncType.flags & TypeFlags.Union) && !(getReducedType(apparentFuncType).flags & TypeFlags.Never) && isTypeAssignableTo(funcType, globalFunctionType); + } + + function resolveNewExpression(node: NewExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + let expressionType = checkNonNullExpression(node.expression); + if (expressionType === silentNeverType) { + return silentNeverSignature; + } + + // If expressionType's apparent type(section 3.8.1) is an object type with one or + // more construct signatures, the expression is processed in the same manner as a + // function call, but using the construct signatures as the initial set of candidate + // signatures for overload resolution. The result type of the function call becomes + // the result type of the operation. + expressionType = getApparentType(expressionType); + if (isErrorType(expressionType)) { + // Another error has already been reported + return resolveErrorCall(node); + } + + // TS 1.0 spec: 4.11 + // If expressionType is of type Any, Args can be any argument + // list and the result of the operation is of type Any. + if (isTypeAny(expressionType)) { + if (node.typeArguments) { + error(node, Diagnostics.Untyped_function_calls_may_not_accept_type_arguments); + } + return resolveUntypedCall(node); + } + + // Technically, this signatures list may be incomplete. We are taking the apparent type, + // but we are not including construct signatures that may have been added to the Object or + // Function interface, since they have none by default. This is a bit of a leap of faith + // that the user will not add any. + const constructSignatures = getSignaturesOfType(expressionType, SignatureKind.Construct); + if (constructSignatures.length) { + if (!isConstructorAccessible(node, constructSignatures[0])) { + return resolveErrorCall(node); + } + // If the expression is a class of abstract type, or an abstract construct signature, + // then it cannot be instantiated. + // In the case of a merged class-module or class-interface declaration, + // only the class declaration node will have the Abstract flag set. + if (someSignature(constructSignatures, signature => !!(signature.flags & SignatureFlags.Abstract))) { + error(node, Diagnostics.Cannot_create_an_instance_of_an_abstract_class); + return resolveErrorCall(node); + } + const valueDecl = expressionType.symbol && getClassLikeDeclarationOfSymbol(expressionType.symbol); + if (valueDecl && hasSyntacticModifier(valueDecl, ModifierFlags.Abstract)) { + error(node, Diagnostics.Cannot_create_an_instance_of_an_abstract_class); + return resolveErrorCall(node); + } + + return resolveCall(node, constructSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + + // If expressionType's apparent type is an object type with no construct signatures but + // one or more call signatures, the expression is processed as a function call. A compile-time + // error occurs if the result of the function call is not Void. The type of the result of the + // operation is Any. It is an error to have a Void this type. + const callSignatures = getSignaturesOfType(expressionType, SignatureKind.Call); + if (callSignatures.length) { + const signature = resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + if (!noImplicitAny) { + if (signature.declaration && !isJSConstructor(signature.declaration) && getReturnTypeOfSignature(signature) !== voidType) { + error(node, Diagnostics.Only_a_void_function_can_be_called_with_the_new_keyword); + } + if (getThisTypeOfSignature(signature) === voidType) { + error(node, Diagnostics.A_function_that_is_called_with_the_new_keyword_cannot_have_a_this_type_that_is_void); + } + } + return signature; + } + + invocationError(node.expression, expressionType, SignatureKind.Construct); + return resolveErrorCall(node); + } + + function someSignature(signatures: Signature | readonly Signature[], f: (s: Signature) => boolean): boolean { + if (isArray(signatures)) { + return some(signatures, signature => someSignature(signature, f)); + } + return signatures.compositeKind === TypeFlags.Union ? some(signatures.compositeSignatures, f) : f(signatures); + } + + function typeHasProtectedAccessibleBase(target: Symbol, type: InterfaceType): boolean { + const baseTypes = getBaseTypes(type); + if (!length(baseTypes)) { + return false; + } + const firstBase = baseTypes[0]; + if (firstBase.flags & TypeFlags.Intersection) { + const types = (firstBase as IntersectionType).types; + const mixinFlags = findMixins(types); + let i = 0; + for (const intersectionMember of (firstBase as IntersectionType).types) { + // We want to ignore mixin ctors + if (!mixinFlags[i]) { + if (getObjectFlags(intersectionMember) & (ObjectFlags.Class | ObjectFlags.Interface)) { + if (intersectionMember.symbol === target) { + return true; + } + if (typeHasProtectedAccessibleBase(target, intersectionMember as InterfaceType)) { + return true; + } + } + } + i++; + } + return false; + } + if (firstBase.symbol === target) { + return true; + } + return typeHasProtectedAccessibleBase(target, firstBase as InterfaceType); + } + + function isConstructorAccessible(node: NewExpression, signature: Signature) { + if (!signature || !signature.declaration) { + return true; + } + + const declaration = signature.declaration; + const modifiers = getSelectedEffectiveModifierFlags(declaration, ModifierFlags.NonPublicAccessibilityModifier); + + // (1) Public constructors and (2) constructor functions are always accessible. + if (!modifiers || declaration.kind !== SyntaxKind.Constructor) { + return true; + } + + const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(declaration.parent.symbol)!; + const declaringClass = getDeclaredTypeOfSymbol(declaration.parent.symbol) as InterfaceType; + + // A private or protected constructor can only be instantiated within its own class (or a subclass, for protected) + if (!isNodeWithinClass(node, declaringClassDeclaration)) { + const containingClass = getContainingClass(node); + if (containingClass && modifiers & ModifierFlags.Protected) { + const containingType = getTypeOfNode(containingClass); + if (typeHasProtectedAccessibleBase(declaration.parent.symbol, containingType as InterfaceType)) { + return true; + } + } + if (modifiers & ModifierFlags.Private) { + error(node, Diagnostics.Constructor_of_class_0_is_private_and_only_accessible_within_the_class_declaration, typeToString(declaringClass)); + } + if (modifiers & ModifierFlags.Protected) { + error(node, Diagnostics.Constructor_of_class_0_is_protected_and_only_accessible_within_the_class_declaration, typeToString(declaringClass)); + } + return false; + } + + return true; + } + + function invocationErrorDetails(errorTarget: Node, apparentType: Type, kind: SignatureKind): { messageChain: DiagnosticMessageChain; relatedMessage: DiagnosticMessage | undefined; } { + let errorInfo: DiagnosticMessageChain | undefined; + const isCall = kind === SignatureKind.Call; + const awaitedType = getAwaitedType(apparentType); + const maybeMissingAwait = awaitedType && getSignaturesOfType(awaitedType, kind).length > 0; + if (apparentType.flags & TypeFlags.Union) { + const types = (apparentType as UnionType).types; + let hasSignatures = false; + for (const constituent of types) { + const signatures = getSignaturesOfType(constituent, kind); + if (signatures.length !== 0) { + hasSignatures = true; + if (errorInfo) { + // Bail early if we already have an error, no chance of "No constituent of type is callable" + break; + } + } + else { + // Error on the first non callable constituent only + if (!errorInfo) { + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Type_0_has_no_call_signatures : + Diagnostics.Type_0_has_no_construct_signatures, + typeToString(constituent), + ); + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Not_all_constituents_of_type_0_are_callable : + Diagnostics.Not_all_constituents_of_type_0_are_constructable, + typeToString(apparentType), + ); + } + if (hasSignatures) { + // Bail early if we already found a siganture, no chance of "No constituent of type is callable" + break; + } + } + } + if (!hasSignatures) { + errorInfo = chainDiagnosticMessages( + /*details*/ undefined, + isCall ? + Diagnostics.No_constituent_of_type_0_is_callable : + Diagnostics.No_constituent_of_type_0_is_constructable, + typeToString(apparentType), + ); + } + if (!errorInfo) { + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Each_member_of_the_union_type_0_has_signatures_but_none_of_those_signatures_are_compatible_with_each_other : + Diagnostics.Each_member_of_the_union_type_0_has_construct_signatures_but_none_of_those_signatures_are_compatible_with_each_other, + typeToString(apparentType), + ); + } + } + else { + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Type_0_has_no_call_signatures : + Diagnostics.Type_0_has_no_construct_signatures, + typeToString(apparentType), + ); + } + + let headMessage = isCall ? Diagnostics.This_expression_is_not_callable : Diagnostics.This_expression_is_not_constructable; + + // Diagnose get accessors incorrectly called as functions + if (isCallExpression(errorTarget.parent) && errorTarget.parent.arguments.length === 0) { + const { resolvedSymbol } = getNodeLinks(errorTarget); + if (resolvedSymbol && resolvedSymbol.flags & SymbolFlags.GetAccessor) { + headMessage = Diagnostics.This_expression_is_not_callable_because_it_is_a_get_accessor_Did_you_mean_to_use_it_without; + } + } + + return { + messageChain: chainDiagnosticMessages(errorInfo, headMessage), + relatedMessage: maybeMissingAwait ? Diagnostics.Did_you_forget_to_use_await : undefined, + }; + } + function invocationError(errorTarget: Node, apparentType: Type, kind: SignatureKind, relatedInformation?: DiagnosticRelatedInformation) { + const { messageChain, relatedMessage: relatedInfo } = invocationErrorDetails(errorTarget, apparentType, kind); + const diagnostic = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorTarget), errorTarget, messageChain); + if (relatedInfo) { + addRelatedInfo(diagnostic, createDiagnosticForNode(errorTarget, relatedInfo)); + } + if (isCallExpression(errorTarget.parent)) { + const { start, length } = getDiagnosticSpanForCallNode(errorTarget.parent); + diagnostic.start = start; + diagnostic.length = length; + } + diagnostics.add(diagnostic); + invocationErrorRecovery(apparentType, kind, relatedInformation ? addRelatedInfo(diagnostic, relatedInformation) : diagnostic); + } + + function invocationErrorRecovery(apparentType: Type, kind: SignatureKind, diagnostic: Diagnostic) { + if (!apparentType.symbol) { + return; + } + const importNode = getSymbolLinks(apparentType.symbol).originatingImport; + // Create a diagnostic on the originating import if possible onto which we can attach a quickfix + // An import call expression cannot be rewritten into another form to correct the error - the only solution is to use `.default` at the use-site + if (importNode && !isImportCall(importNode)) { + const sigs = getSignaturesOfType(getTypeOfSymbol(getSymbolLinks(apparentType.symbol).target!), kind); + if (!sigs || !sigs.length) return; + + addRelatedInfo(diagnostic, createDiagnosticForNode(importNode, Diagnostics.Type_originates_at_this_import_A_namespace_style_import_cannot_be_called_or_constructed_and_will_cause_a_failure_at_runtime_Consider_using_a_default_import_or_import_require_here_instead)); + } + } + + function resolveTaggedTemplateExpression(node: TaggedTemplateExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + const tagType = checkExpression(node.tag); + const apparentType = getApparentType(tagType); + + if (isErrorType(apparentType)) { + // Another error has already been reported + return resolveErrorCall(node); + } + + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; + + if (isUntypedFunctionCall(tagType, apparentType, callSignatures.length, numConstructSignatures)) { + return resolveUntypedCall(node); + } + + if (!callSignatures.length) { + if (isArrayLiteralExpression(node.parent)) { + const diagnostic = createDiagnosticForNode(node.tag, Diagnostics.It_is_likely_that_you_are_missing_a_comma_to_separate_these_two_template_expressions_They_form_a_tagged_template_expression_which_cannot_be_invoked); + diagnostics.add(diagnostic); + return resolveErrorCall(node); + } + + invocationError(node.tag, apparentType, SignatureKind.Call); + return resolveErrorCall(node); + } + + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + + /** + * Gets the localized diagnostic head message to use for errors when resolving a decorator as a call expression. + */ + function getDiagnosticHeadMessageForDecoratorResolution(node: Decorator) { + switch (node.parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + return Diagnostics.Unable_to_resolve_signature_of_class_decorator_when_called_as_an_expression; + + case SyntaxKind.Parameter: + return Diagnostics.Unable_to_resolve_signature_of_parameter_decorator_when_called_as_an_expression; + + case SyntaxKind.PropertyDeclaration: + return Diagnostics.Unable_to_resolve_signature_of_property_decorator_when_called_as_an_expression; + + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return Diagnostics.Unable_to_resolve_signature_of_method_decorator_when_called_as_an_expression; + + default: + return Debug.fail(); + } + } + + /** + * Resolves a decorator as if it were a call expression. + */ + function resolveDecorator(node: Decorator, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + const funcType = checkExpression(node.expression); + const apparentType = getApparentType(funcType); + if (isErrorType(apparentType)) { + return resolveErrorCall(node); + } + + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; + if (isUntypedFunctionCall(funcType, apparentType, callSignatures.length, numConstructSignatures)) { + return resolveUntypedCall(node); + } + + if (isPotentiallyUncalledDecorator(node, callSignatures) && !isParenthesizedExpression(node.expression)) { + const nodeStr = getTextOfNode(node.expression, /*includeTrivia*/ false); + error(node, Diagnostics._0_accepts_too_few_arguments_to_be_used_as_a_decorator_here_Did_you_mean_to_call_it_first_and_write_0, nodeStr); + return resolveErrorCall(node); + } + + const headMessage = getDiagnosticHeadMessageForDecoratorResolution(node); + if (!callSignatures.length) { + const errorDetails = invocationErrorDetails(node.expression, apparentType, SignatureKind.Call); + const messageChain = chainDiagnosticMessages(errorDetails.messageChain, headMessage); + const diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node.expression), node.expression, messageChain); + if (errorDetails.relatedMessage) { + addRelatedInfo(diag, createDiagnosticForNode(node.expression, errorDetails.relatedMessage)); + } + diagnostics.add(diag); + invocationErrorRecovery(apparentType, SignatureKind.Call, diag); + return resolveErrorCall(node); + } + + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None, headMessage); + } + + function createSignatureForJSXIntrinsic(node: JsxOpeningLikeElement, result: Type): Signature { + const namespace = getJsxNamespaceAt(node); + const exports = namespace && getExportsOfSymbol(namespace); + // We fake up a SFC signature for each intrinsic, however a more specific per-element signature drawn from the JSX declaration + // file would probably be preferable. + const typeSymbol = exports && getSymbol(exports, JsxNames.Element, SymbolFlags.Type); + const returnNode = typeSymbol && nodeBuilder.symbolToEntityName(typeSymbol, SymbolFlags.Type, node); + const declaration = factory.createFunctionTypeNode(/*typeParameters*/ undefined, [factory.createParameterDeclaration(/*modifiers*/ undefined, /*dotDotDotToken*/ undefined, "props", /*questionToken*/ undefined, nodeBuilder.typeToTypeNode(result, node))], returnNode ? factory.createTypeReferenceNode(returnNode, /*typeArguments*/ undefined) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword)); + const parameterSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "props" as __String); + parameterSymbol.links.type = result; + return createSignature( + declaration, + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [parameterSymbol], + typeSymbol ? getDeclaredTypeOfSymbol(typeSymbol) : errorType, + /*resolvedTypePredicate*/ undefined, + 1, + SignatureFlags.None, + ); + } + + function resolveJsxOpeningLikeElement(node: JsxOpeningLikeElement, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + if (isJsxIntrinsicTagName(node.tagName)) { + const result = getIntrinsicAttributesTypeFromJsxOpeningLikeElement(node); + const fakeSignature = createSignatureForJSXIntrinsic(node, result); + checkTypeAssignableToAndOptionallyElaborate(checkExpressionWithContextualType(node.attributes, getEffectiveFirstArgumentForJsxSignature(fakeSignature, node), /*inferenceContext*/ undefined, CheckMode.Normal), result, node.tagName, node.attributes); + if (length(node.typeArguments)) { + forEach(node.typeArguments, checkSourceElement); + diagnostics.add(createDiagnosticForNodeArray(getSourceFileOfNode(node), node.typeArguments!, Diagnostics.Expected_0_type_arguments_but_got_1, 0, length(node.typeArguments))); + } + return fakeSignature; + } + const exprTypes = checkExpression(node.tagName); + const apparentType = getApparentType(exprTypes); + if (isErrorType(apparentType)) { + return resolveErrorCall(node); + } + + const signatures = getUninstantiatedJsxSignaturesOfType(exprTypes, node); + if (isUntypedFunctionCall(exprTypes, apparentType, signatures.length, /*constructSignatures*/ 0)) { + return resolveUntypedCall(node); + } + + if (signatures.length === 0) { + // We found no signatures at all, which is an error + error(node.tagName, Diagnostics.JSX_element_type_0_does_not_have_any_construct_or_call_signatures, getTextOfNode(node.tagName)); + return resolveErrorCall(node); + } + + return resolveCall(node, signatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + + function resolveInstanceofExpression(node: InstanceofExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + // if rightType is an object type with a custom `[Symbol.hasInstance]` method, then it is potentially + // valid on the right-hand side of the `instanceof` operator. This allows normal `object` types to + // participate in `instanceof`, as per Step 2 of https://tc39.es/ecma262/#sec-instanceofoperator. + const rightType = checkExpression(node.right); + if (!isTypeAny(rightType)) { + const hasInstanceMethodType = getSymbolHasInstanceMethodOfObjectType(rightType); + if (hasInstanceMethodType) { + const apparentType = getApparentType(hasInstanceMethodType); + if (isErrorType(apparentType)) { + return resolveErrorCall(node); + } + + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const constructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct); + if (isUntypedFunctionCall(hasInstanceMethodType, apparentType, callSignatures.length, constructSignatures.length)) { + return resolveUntypedCall(node); + } + + if (callSignatures.length) { + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + } + // NOTE: do not raise error if right is unknown as related error was already reported + else if (!(typeHasCallOrConstructSignatures(rightType) || isTypeSubtypeOf(rightType, globalFunctionType))) { + error(node.right, Diagnostics.The_right_hand_side_of_an_instanceof_expression_must_be_either_of_type_any_a_class_function_or_other_type_assignable_to_the_Function_interface_type_or_an_object_type_with_a_Symbol_hasInstance_method); + return resolveErrorCall(node); + } + } + // fall back to a default signature + return anySignature; + } + + /** + * Sometimes, we have a decorator that could accept zero arguments, + * but is receiving too many arguments as part of the decorator invocation. + * In those cases, a user may have meant to *call* the expression before using it as a decorator. + */ + function isPotentiallyUncalledDecorator(decorator: Decorator, signatures: readonly Signature[]) { + return signatures.length && every(signatures, signature => + signature.minArgumentCount === 0 && + !signatureHasRestParameter(signature) && + signature.parameters.length < getDecoratorArgumentCount(decorator, signature)); + } + + function resolveSignature(node: CallLikeExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + switch (node.kind) { + case SyntaxKind.CallExpression: + return resolveCallExpression(node, candidatesOutArray, checkMode); + case SyntaxKind.NewExpression: + return resolveNewExpression(node, candidatesOutArray, checkMode); + case SyntaxKind.TaggedTemplateExpression: + return resolveTaggedTemplateExpression(node, candidatesOutArray, checkMode); + case SyntaxKind.Decorator: + return resolveDecorator(node, candidatesOutArray, checkMode); + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.JsxSelfClosingElement: + return resolveJsxOpeningLikeElement(node, candidatesOutArray, checkMode); + case SyntaxKind.BinaryExpression: + return resolveInstanceofExpression(node, candidatesOutArray, checkMode); + } + Debug.assertNever(node, "Branch in 'resolveSignature' should be unreachable."); + } + + /** + * Resolve a signature of a given call-like expression. + * @param node a call-like expression to try resolve a signature for + * @param candidatesOutArray an array of signature to be filled in by the function. It is passed by signature help in the language service; + * the function will fill it up with appropriate candidate signatures + * @return a signature of the call-like expression or undefined if one can't be found + */ + function getResolvedSignature(node: CallLikeExpression, candidatesOutArray?: Signature[] | undefined, checkMode?: CheckMode): Signature { + const links = getNodeLinks(node); + // If getResolvedSignature has already been called, we will have cached the resolvedSignature. + // However, it is possible that either candidatesOutArray was not passed in the first time, + // or that a different candidatesOutArray was passed in. Therefore, we need to redo the work + // to correctly fill the candidatesOutArray. + const cached = links.resolvedSignature; + if (cached && cached !== resolvingSignature && !candidatesOutArray) { + return cached; + } + const saveResolutionStart = resolutionStart; + if (!cached) { + // If we haven't already done so, temporarily reset the resolution stack. This allows us to + // handle "inverted" situations where, for example, an API client asks for the type of a symbol + // containined in a function call argument whose contextual type depends on the symbol itself + // through resolution of the containing function call. By resetting the resolution stack we'll + // retry the symbol type resolution with the resolvingSignature marker in place to suppress + // the contextual type circularity. + resolutionStart = resolutionTargets.length; + } + links.resolvedSignature = resolvingSignature; + let result = resolveSignature(node, candidatesOutArray, checkMode || CheckMode.Normal); + resolutionStart = saveResolutionStart; + // When CheckMode.SkipGenericFunctions is set we use resolvingSignature to indicate that call + // resolution should be deferred. + if (result !== resolvingSignature) { + // if the signature resolution originated on a node that itself depends on the contextual type + // then it's possible that the resolved signature might not be the same as the one that would be computed in source order + // since resolving such signature leads to resolving the potential outer signature, its arguments and thus the very same signature + // it's possible that this inner resolution sets the resolvedSignature first. + // In such a case we ignore the local result and reuse the correct one that was cached. + if (links.resolvedSignature !== resolvingSignature) { + result = links.resolvedSignature; + } + // If signature resolution originated in control flow type analysis (for example to compute the + // assigned type in a flow assignment) we don't cache the result as it may be based on temporary + // types from the control flow analysis. + links.resolvedSignature = flowLoopStart === flowLoopCount ? result : cached; + } + return result; + } + + /** + * Indicates whether a declaration can be treated as a constructor in a JavaScript + * file. + */ + function isJSConstructor(node: Node | undefined): node is FunctionDeclaration | FunctionExpression { + if (!node || !isInJSFile(node)) { + return false; + } + const func = isFunctionDeclaration(node) || isFunctionExpression(node) ? node : + (isVariableDeclaration(node) || isPropertyAssignment(node)) && node.initializer && isFunctionExpression(node.initializer) ? node.initializer : + undefined; + if (func) { + // If the node has a @class or @constructor tag, treat it like a constructor. + if (getJSDocClassTag(node)) return true; + + // If the node is a property of an object literal. + if (isPropertyAssignment(walkUpParenthesizedExpressions(func.parent))) return false; + + // If the symbol of the node has members, treat it like a constructor. + const symbol = getSymbolOfDeclaration(func); + return !!symbol?.members?.size; + } + return false; + } + + function mergeJSSymbols(target: Symbol, source: Symbol | undefined) { + if (source) { + const links = getSymbolLinks(source); + if (!links.inferredClassSymbol || !links.inferredClassSymbol.has(getSymbolId(target))) { + const inferred = isTransientSymbol(target) ? target : cloneSymbol(target); + inferred.exports = inferred.exports || createSymbolTable(); + inferred.members = inferred.members || createSymbolTable(); + inferred.flags |= source.flags & SymbolFlags.Class; + if (source.exports?.size) { + mergeSymbolTable(inferred.exports, source.exports); + } + if (source.members?.size) { + mergeSymbolTable(inferred.members, source.members); + } + (links.inferredClassSymbol || (links.inferredClassSymbol = new Map())).set(getSymbolId(inferred), inferred); + return inferred; + } + return links.inferredClassSymbol.get(getSymbolId(target)); + } + } + + function getAssignedClassSymbol(decl: Declaration): Symbol | undefined { + const assignmentSymbol = decl && getSymbolOfExpando(decl, /*allowDeclaration*/ true); + const prototype = assignmentSymbol?.exports?.get("prototype" as __String); + const init = prototype?.valueDeclaration && getAssignedJSPrototype(prototype.valueDeclaration); + return init ? getSymbolOfDeclaration(init) : undefined; + } + + function getSymbolOfExpando(node: Node, allowDeclaration: boolean): Symbol | undefined { + if (!node.parent) { + return undefined; + } + let name: Expression | BindingName | undefined; + let decl: Node | undefined; + if (isVariableDeclaration(node.parent) && node.parent.initializer === node) { + if (!isInJSFile(node) && !(isVarConstLike(node.parent) && isFunctionLikeDeclaration(node))) { + return undefined; + } + name = node.parent.name; + decl = node.parent; + } + else if (isBinaryExpression(node.parent)) { + const parentNode = node.parent; + const parentNodeOperator = node.parent.operatorToken.kind; + if (parentNodeOperator === SyntaxKind.EqualsToken && (allowDeclaration || parentNode.right === node)) { + name = parentNode.left; + decl = name; + } + else if (parentNodeOperator === SyntaxKind.BarBarToken || parentNodeOperator === SyntaxKind.QuestionQuestionToken) { + if (isVariableDeclaration(parentNode.parent) && parentNode.parent.initializer === parentNode) { + name = parentNode.parent.name; + decl = parentNode.parent; + } + else if (isBinaryExpression(parentNode.parent) && parentNode.parent.operatorToken.kind === SyntaxKind.EqualsToken && (allowDeclaration || parentNode.parent.right === parentNode)) { + name = parentNode.parent.left; + decl = name; + } + + if (!name || !isBindableStaticNameExpression(name) || !isSameEntityName(name, parentNode.left)) { + return undefined; + } + } + } + else if (allowDeclaration && isFunctionDeclaration(node)) { + name = node.name; + decl = node; + } + + if (!decl || !name || (!allowDeclaration && !getExpandoInitializer(node, isPrototypeAccess(name)))) { + return undefined; + } + return getSymbolOfNode(decl); + } + + function getAssignedJSPrototype(node: Node) { + if (!node.parent) { + return false; + } + let parent: Node = node.parent; + while (parent && parent.kind === SyntaxKind.PropertyAccessExpression) { + parent = parent.parent; + } + if (parent && isBinaryExpression(parent) && isPrototypeAccess(parent.left) && parent.operatorToken.kind === SyntaxKind.EqualsToken) { + const right = getInitializerOfBinaryExpression(parent); + return isObjectLiteralExpression(right) && right; + } + } + + /** + * Syntactically and semantically checks a call or new expression. + * @param node The call/new expression to be checked. + * @returns On success, the expression's signature's return type. On failure, anyType. + */ + function checkCallExpression(node: CallExpression | NewExpression, checkMode?: CheckMode): Type { + checkGrammarTypeArguments(node, node.typeArguments); + + const signature = getResolvedSignature(node, /*candidatesOutArray*/ undefined, checkMode); + if (signature === resolvingSignature) { + // CheckMode.SkipGenericFunctions is enabled and this is a call to a generic function that + // returns a function type. We defer checking and return silentNeverType. + return silentNeverType; + } + + checkDeprecatedSignature(signature, node); + + if (node.expression.kind === SyntaxKind.SuperKeyword) { + return voidType; + } + + if (node.kind === SyntaxKind.NewExpression) { + const declaration = signature.declaration; + + if ( + declaration && + declaration.kind !== SyntaxKind.Constructor && + declaration.kind !== SyntaxKind.ConstructSignature && + declaration.kind !== SyntaxKind.ConstructorType && + !(isJSDocSignature(declaration) && getJSDocRoot(declaration)?.parent?.kind === SyntaxKind.Constructor) && + !isJSDocConstructSignature(declaration) && + !isJSConstructor(declaration) + ) { + // When resolved signature is a call signature (and not a construct signature) the result type is any + if (noImplicitAny) { + error(node, Diagnostics.new_expression_whose_target_lacks_a_construct_signature_implicitly_has_an_any_type); + } + return anyType; + } + } + + // In JavaScript files, calls to any identifier 'require' are treated as external module imports + if (isInJSFile(node) && isCommonJsRequire(node)) { + return resolveExternalModuleTypeByLiteral(node.arguments![0] as StringLiteral); + } + + const returnType = getReturnTypeOfSignature(signature); + // Treat any call to the global 'Symbol' function that is part of a const variable or readonly property + // as a fresh unique symbol literal type. + if (returnType.flags & TypeFlags.ESSymbolLike && isSymbolOrSymbolForCall(node)) { + return getESSymbolLikeTypeForNode(walkUpParenthesizedExpressions(node.parent)); + } + if ( + node.kind === SyntaxKind.CallExpression && !node.questionDotToken && node.parent.kind === SyntaxKind.ExpressionStatement && + returnType.flags & TypeFlags.Void && getTypePredicateOfSignature(signature) + ) { + if (!isDottedName(node.expression)) { + error(node.expression, Diagnostics.Assertions_require_the_call_target_to_be_an_identifier_or_qualified_name); + } + else if (!getEffectsSignature(node)) { + const diagnostic = error(node.expression, Diagnostics.Assertions_require_every_name_in_the_call_target_to_be_declared_with_an_explicit_type_annotation); + getTypeOfDottedName(node.expression, diagnostic); + } + } + + if (isInJSFile(node)) { + const jsSymbol = getSymbolOfExpando(node, /*allowDeclaration*/ false); + if (jsSymbol?.exports?.size) { + const jsAssignmentType = createAnonymousType(jsSymbol, jsSymbol.exports, emptyArray, emptyArray, emptyArray); + jsAssignmentType.objectFlags |= ObjectFlags.JSLiteral; + return getIntersectionType([returnType, jsAssignmentType]); + } + } + + return returnType; + } + + function checkDeprecatedSignature(signature: Signature, node: CallLikeExpression) { + if (signature.flags & SignatureFlags.IsSignatureCandidateForOverloadFailure) return; + if (signature.declaration && signature.declaration.flags & NodeFlags.Deprecated) { + const suggestionNode = getDeprecatedSuggestionNode(node); + const name = tryGetPropertyAccessOrIdentifierToString(getInvokedExpression(node)); + addDeprecatedSuggestionWithSignature(suggestionNode, signature.declaration, name, signatureToString(signature)); + } + } + + function getDeprecatedSuggestionNode(node: Node): Node { + node = skipParentheses(node); + switch (node.kind) { + case SyntaxKind.CallExpression: + case SyntaxKind.Decorator: + case SyntaxKind.NewExpression: + return getDeprecatedSuggestionNode((node as Decorator | CallExpression | NewExpression).expression); + case SyntaxKind.TaggedTemplateExpression: + return getDeprecatedSuggestionNode((node as TaggedTemplateExpression).tag); + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.JsxSelfClosingElement: + return getDeprecatedSuggestionNode((node as JsxOpeningLikeElement).tagName); + case SyntaxKind.ElementAccessExpression: + return (node as ElementAccessExpression).argumentExpression; + case SyntaxKind.PropertyAccessExpression: + return (node as PropertyAccessExpression).name; + case SyntaxKind.TypeReference: + const typeReference = node as TypeReferenceNode; + return isQualifiedName(typeReference.typeName) ? typeReference.typeName.right : typeReference; + default: + return node; + } + } + + function isSymbolOrSymbolForCall(node: Node) { + if (!isCallExpression(node)) return false; + let left = node.expression; + if (isPropertyAccessExpression(left) && left.name.escapedText === "for") { + left = left.expression; + } + if (!isIdentifier(left) || left.escapedText !== "Symbol") { + return false; + } + + // make sure `Symbol` is the global symbol + const globalESSymbol = getGlobalESSymbolConstructorSymbol(/*reportErrors*/ false); + if (!globalESSymbol) { + return false; + } + + return globalESSymbol === resolveName(left, "Symbol" as __String, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + } + + function checkImportCallExpression(node: ImportCall): Type { + // Check grammar of dynamic import + checkGrammarImportCallExpression(node); + + if (node.arguments.length === 0) { + return createPromiseReturnType(node, anyType); + } + + const specifier = node.arguments[0]; + const specifierType = checkExpressionCached(specifier); + const optionsType = node.arguments.length > 1 ? checkExpressionCached(node.arguments[1]) : undefined; + // Even though multiple arguments is grammatically incorrect, type-check extra arguments for completion + for (let i = 2; i < node.arguments.length; ++i) { + checkExpressionCached(node.arguments[i]); + } + + if (specifierType.flags & TypeFlags.Undefined || specifierType.flags & TypeFlags.Null || !isTypeAssignableTo(specifierType, stringType)) { + error(specifier, Diagnostics.Dynamic_import_s_specifier_must_be_of_type_string_but_here_has_type_0, typeToString(specifierType)); + } + + if (optionsType) { + const importCallOptionsType = getGlobalImportCallOptionsType(/*reportErrors*/ true); + if (importCallOptionsType !== emptyObjectType) { + checkTypeAssignableTo(optionsType, getNullableType(importCallOptionsType, TypeFlags.Undefined), node.arguments[1]); + } + } + + // resolveExternalModuleName will return undefined if the moduleReferenceExpression is not a string literal + const moduleSymbol = resolveExternalModuleName(node, specifier); + if (moduleSymbol) { + const esModuleSymbol = resolveESModuleSymbol(moduleSymbol, specifier, /*dontResolveAlias*/ true, /*suppressInteropError*/ false); + if (esModuleSymbol) { + return createPromiseReturnType( + node, + getTypeWithSyntheticDefaultOnly(getTypeOfSymbol(esModuleSymbol), esModuleSymbol, moduleSymbol, specifier) || + getTypeWithSyntheticDefaultImportType(getTypeOfSymbol(esModuleSymbol), esModuleSymbol, moduleSymbol, specifier), + ); + } + } + return createPromiseReturnType(node, anyType); + } + + function createDefaultPropertyWrapperForModule(symbol: Symbol, originalSymbol: Symbol | undefined, anonymousSymbol?: Symbol | undefined) { + const memberTable = createSymbolTable(); + const newSymbol = createSymbol(SymbolFlags.Alias, InternalSymbolName.Default); + newSymbol.parent = originalSymbol; + newSymbol.links.nameType = getStringLiteralType("default"); + newSymbol.links.aliasTarget = resolveSymbol(symbol); + memberTable.set(InternalSymbolName.Default, newSymbol); + return createAnonymousType(anonymousSymbol, memberTable, emptyArray, emptyArray, emptyArray); + } + + function getTypeWithSyntheticDefaultOnly(type: Type, symbol: Symbol, originalSymbol: Symbol, moduleSpecifier: Expression) { + const hasDefaultOnly = isOnlyImportedAsDefault(moduleSpecifier); + if (hasDefaultOnly && type && !isErrorType(type)) { + const synthType = type as SyntheticDefaultModuleType; + if (!synthType.defaultOnlyType) { + const type = createDefaultPropertyWrapperForModule(symbol, originalSymbol); + synthType.defaultOnlyType = type; + } + return synthType.defaultOnlyType; + } + return undefined; + } + + function getTypeWithSyntheticDefaultImportType(type: Type, symbol: Symbol, originalSymbol: Symbol, moduleSpecifier: Expression): Type { + if (allowSyntheticDefaultImports && type && !isErrorType(type)) { + const synthType = type as SyntheticDefaultModuleType; + if (!synthType.syntheticType) { + const file = originalSymbol.declarations?.find(isSourceFile); + const hasSyntheticDefault = canHaveSyntheticDefault(file, originalSymbol, /*dontResolveAlias*/ false, moduleSpecifier); + if (hasSyntheticDefault) { + const anonymousSymbol = createSymbol(SymbolFlags.TypeLiteral, InternalSymbolName.Type); + const defaultContainingObject = createDefaultPropertyWrapperForModule(symbol, originalSymbol, anonymousSymbol); + anonymousSymbol.links.type = defaultContainingObject; + synthType.syntheticType = isValidSpreadType(type) ? getSpreadType(type, defaultContainingObject, anonymousSymbol, /*objectFlags*/ 0, /*readonly*/ false) : defaultContainingObject; + } + else { + synthType.syntheticType = type; + } + } + return synthType.syntheticType; + } + return type; + } + + function isCommonJsRequire(node: Node): boolean { + if (!isRequireCall(node, /*requireStringLiteralLikeArgument*/ true)) { + return false; + } + + // Make sure require is not a local function + if (!isIdentifier(node.expression)) return Debug.fail(); + const resolvedRequire = resolveName(node.expression, node.expression.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true)!; // TODO: GH#18217 + if (resolvedRequire === requireSymbol) { + return true; + } + // project includes symbol named 'require' - make sure that it is ambient and local non-alias + if (resolvedRequire.flags & SymbolFlags.Alias) { + return false; + } + + const targetDeclarationKind = resolvedRequire.flags & SymbolFlags.Function + ? SyntaxKind.FunctionDeclaration + : resolvedRequire.flags & SymbolFlags.Variable + ? SyntaxKind.VariableDeclaration + : SyntaxKind.Unknown; + if (targetDeclarationKind !== SyntaxKind.Unknown) { + const decl = getDeclarationOfKind(resolvedRequire, targetDeclarationKind)!; + // function/variable declaration should be ambient + return !!decl && !!(decl.flags & NodeFlags.Ambient); + } + return false; + } + + function checkTaggedTemplateExpression(node: TaggedTemplateExpression): Type { + if (!checkGrammarTaggedTemplateChain(node)) checkGrammarTypeArguments(node, node.typeArguments); + if (languageVersion < LanguageFeatureMinimumTarget.TaggedTemplates) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.MakeTemplateObject); + } + const signature = getResolvedSignature(node); + checkDeprecatedSignature(signature, node); + return getReturnTypeOfSignature(signature); + } + + function checkAssertion(node: AssertionExpression, checkMode: CheckMode | undefined) { + if (node.kind === SyntaxKind.TypeAssertionExpression) { + const file = getSourceFileOfNode(node); + if (file && fileExtensionIsOneOf(file.fileName, [Extension.Cts, Extension.Mts])) { + grammarErrorOnNode(node, Diagnostics.This_syntax_is_reserved_in_files_with_the_mts_or_cts_extension_Use_an_as_expression_instead); + } + } + return checkAssertionWorker(node, checkMode); + } + + function isValidConstAssertionArgument(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.StringLiteral: + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.NumericLiteral: + case SyntaxKind.BigIntLiteral: + case SyntaxKind.TrueKeyword: + case SyntaxKind.FalseKeyword: + case SyntaxKind.ArrayLiteralExpression: + case SyntaxKind.ObjectLiteralExpression: + case SyntaxKind.TemplateExpression: + return true; + case SyntaxKind.ParenthesizedExpression: + return isValidConstAssertionArgument((node as ParenthesizedExpression).expression); + case SyntaxKind.PrefixUnaryExpression: + const op = (node as PrefixUnaryExpression).operator; + const arg = (node as PrefixUnaryExpression).operand; + return op === SyntaxKind.MinusToken && (arg.kind === SyntaxKind.NumericLiteral || arg.kind === SyntaxKind.BigIntLiteral) || + op === SyntaxKind.PlusToken && arg.kind === SyntaxKind.NumericLiteral; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + const expr = skipParentheses((node as PropertyAccessExpression | ElementAccessExpression).expression); + const symbol = isEntityNameExpression(expr) ? resolveEntityName(expr, SymbolFlags.Value, /*ignoreErrors*/ true) : undefined; + return !!(symbol && symbol.flags & SymbolFlags.Enum); + } + return false; + } + + function checkAssertionWorker(node: JSDocTypeAssertion | AssertionExpression, checkMode: CheckMode | undefined) { + const { type, expression } = getAssertionTypeAndExpression(node); + const exprType = checkExpression(expression, checkMode); + if (isConstTypeReference(type)) { + if (!isValidConstAssertionArgument(expression)) { + error(expression, Diagnostics.A_const_assertions_can_only_be_applied_to_references_to_enum_members_or_string_number_boolean_array_or_object_literals); + } + return getRegularTypeOfLiteralType(exprType); + } + const links = getNodeLinks(node); + links.assertionExpressionType = exprType; + checkSourceElement(type); + checkNodeDeferred(node); + return getTypeFromTypeNode(type); + } + + function getAssertionTypeAndExpression(node: JSDocTypeAssertion | AssertionExpression) { + let type: TypeNode; + let expression: Expression; + switch (node.kind) { + case SyntaxKind.AsExpression: + case SyntaxKind.TypeAssertionExpression: + type = node.type; + expression = node.expression; + break; + case SyntaxKind.ParenthesizedExpression: + type = getJSDocTypeAssertionType(node); + expression = node.expression; + break; + } + + return { type, expression }; + } + + function checkAssertionDeferred(node: JSDocTypeAssertion | AssertionExpression) { + const { type } = getAssertionTypeAndExpression(node); + const errNode = isParenthesizedExpression(node) ? type : node; + const links = getNodeLinks(node); + Debug.assertIsDefined(links.assertionExpressionType); + const exprType = getRegularTypeOfObjectLiteral(getBaseTypeOfLiteralType(links.assertionExpressionType)); + const targetType = getTypeFromTypeNode(type); + if (!isErrorType(targetType)) { + addLazyDiagnostic(() => { + const widenedType = getWidenedType(exprType); + if (!isTypeComparableTo(targetType, widenedType)) { + checkTypeComparableTo(exprType, targetType, errNode, Diagnostics.Conversion_of_type_0_to_type_1_may_be_a_mistake_because_neither_type_sufficiently_overlaps_with_the_other_If_this_was_intentional_convert_the_expression_to_unknown_first); + } + }); + } + } + + function checkNonNullChain(node: NonNullChain) { + const leftType = checkExpression(node.expression); + const nonOptionalType = getOptionalExpressionType(leftType, node.expression); + return propagateOptionalTypeMarker(getNonNullableType(nonOptionalType), node, nonOptionalType !== leftType); + } + + function checkNonNullAssertion(node: NonNullExpression) { + return node.flags & NodeFlags.OptionalChain ? checkNonNullChain(node as NonNullChain) : + getNonNullableType(checkExpression(node.expression)); + } + + function checkExpressionWithTypeArguments(node: ExpressionWithTypeArguments | TypeQueryNode) { + checkGrammarExpressionWithTypeArguments(node); + forEach(node.typeArguments, checkSourceElement); + if (node.kind === SyntaxKind.ExpressionWithTypeArguments) { + const parent = walkUpParenthesizedExpressions(node.parent); + if (parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.InstanceOfKeyword && isNodeDescendantOf(node, (parent as BinaryExpression).right)) { + error(node, Diagnostics.The_right_hand_side_of_an_instanceof_expression_must_not_be_an_instantiation_expression); + } + } + const exprType = node.kind === SyntaxKind.ExpressionWithTypeArguments ? checkExpression(node.expression) : + isThisIdentifier(node.exprName) ? checkThisExpression(node.exprName) : + checkExpression(node.exprName); + return getInstantiationExpressionType(exprType, node); + } + + function getInstantiationExpressionType(exprType: Type, node: NodeWithTypeArguments) { + const typeArguments = node.typeArguments; + if (exprType === silentNeverType || isErrorType(exprType) || !some(typeArguments)) { + return exprType; + } + let hasSomeApplicableSignature = false; + let nonApplicableType: Type | undefined; + const result = getInstantiatedType(exprType); + const errorType = hasSomeApplicableSignature ? nonApplicableType : exprType; + if (errorType) { + diagnostics.add(createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Type_0_has_no_signatures_for_which_the_type_argument_list_is_applicable, typeToString(errorType))); + } + return result; + + function getInstantiatedType(type: Type): Type { + let hasSignatures = false; + let hasApplicableSignature = false; + const result = getInstantiatedTypePart(type); + hasSomeApplicableSignature ||= hasApplicableSignature; + if (hasSignatures && !hasApplicableSignature) { + nonApplicableType ??= type; + } + return result; + + function getInstantiatedTypePart(type: Type): Type { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + const callSignatures = getInstantiatedSignatures(resolved.callSignatures); + const constructSignatures = getInstantiatedSignatures(resolved.constructSignatures); + hasSignatures ||= resolved.callSignatures.length !== 0 || resolved.constructSignatures.length !== 0; + hasApplicableSignature ||= callSignatures.length !== 0 || constructSignatures.length !== 0; + if (callSignatures !== resolved.callSignatures || constructSignatures !== resolved.constructSignatures) { + const result = createAnonymousType(createSymbol(SymbolFlags.None, InternalSymbolName.InstantiationExpression), resolved.members, callSignatures, constructSignatures, resolved.indexInfos) as ResolvedType & InstantiationExpressionType; + result.objectFlags |= ObjectFlags.InstantiationExpressionType; + result.node = node; + return result; + } + } + else if (type.flags & TypeFlags.InstantiableNonPrimitive) { + const constraint = getBaseConstraintOfType(type); + if (constraint) { + const instantiated = getInstantiatedTypePart(constraint); + if (instantiated !== constraint) { + return instantiated; + } + } + } + else if (type.flags & TypeFlags.Union) { + return mapType(type, getInstantiatedType); + } + else if (type.flags & TypeFlags.Intersection) { + return getIntersectionType(sameMap((type as IntersectionType).types, getInstantiatedTypePart)); + } + return type; + } + } + + function getInstantiatedSignatures(signatures: readonly Signature[]) { + const applicableSignatures = filter(signatures, sig => !!sig.typeParameters && hasCorrectTypeArgumentArity(sig, typeArguments)); + return sameMap(applicableSignatures, sig => { + const typeArgumentTypes = checkTypeArguments(sig, typeArguments!, /*reportErrors*/ true); + return typeArgumentTypes ? getSignatureInstantiation(sig, typeArgumentTypes, isInJSFile(sig.declaration)) : sig; + }); + } + } + + function checkSatisfiesExpression(node: SatisfiesExpression) { + checkSourceElement(node.type); + return checkSatisfiesExpressionWorker(node.expression, node.type); + } + + function checkSatisfiesExpressionWorker(expression: Expression, target: TypeNode, checkMode?: CheckMode) { + const exprType = checkExpression(expression, checkMode); + const targetType = getTypeFromTypeNode(target); + if (isErrorType(targetType)) { + return targetType; + } + const errorNode = findAncestor(target.parent, n => n.kind === SyntaxKind.SatisfiesExpression || n.kind === SyntaxKind.JSDocSatisfiesTag); + checkTypeAssignableToAndOptionallyElaborate(exprType, targetType, errorNode, expression, Diagnostics.Type_0_does_not_satisfy_the_expected_type_1); + return exprType; + } + + function checkMetaProperty(node: MetaProperty): Type { + checkGrammarMetaProperty(node); + + if (node.keywordToken === SyntaxKind.NewKeyword) { + return checkNewTargetMetaProperty(node); + } + + if (node.keywordToken === SyntaxKind.ImportKeyword) { + return checkImportMetaProperty(node); + } + + return Debug.assertNever(node.keywordToken); + } + + function checkMetaPropertyKeyword(node: MetaProperty): Type { + switch (node.keywordToken) { + case SyntaxKind.ImportKeyword: + return getGlobalImportMetaExpressionType(); + case SyntaxKind.NewKeyword: + const type = checkNewTargetMetaProperty(node); + return isErrorType(type) ? errorType : createNewTargetExpressionType(type); + default: + Debug.assertNever(node.keywordToken); + } + } + + function checkNewTargetMetaProperty(node: MetaProperty) { + const container = getNewTargetContainer(node); + if (!container) { + error(node, Diagnostics.Meta_property_0_is_only_allowed_in_the_body_of_a_function_declaration_function_expression_or_constructor, "new.target"); + return errorType; + } + else if (container.kind === SyntaxKind.Constructor) { + const symbol = getSymbolOfDeclaration(container.parent); + return getTypeOfSymbol(symbol); + } + else { + const symbol = getSymbolOfDeclaration(container); + return getTypeOfSymbol(symbol); + } + } + + function checkImportMetaProperty(node: MetaProperty) { + if (moduleKind === ModuleKind.Node16 || moduleKind === ModuleKind.NodeNext) { + if (getSourceFileOfNode(node).impliedNodeFormat !== ModuleKind.ESNext) { + error(node, Diagnostics.The_import_meta_meta_property_is_not_allowed_in_files_which_will_build_into_CommonJS_output); + } + } + else if (moduleKind < ModuleKind.ES2020 && moduleKind !== ModuleKind.System) { + error(node, Diagnostics.The_import_meta_meta_property_is_only_allowed_when_the_module_option_is_es2020_es2022_esnext_system_node16_or_nodenext); + } + const file = getSourceFileOfNode(node); + Debug.assert(!!(file.flags & NodeFlags.PossiblyContainsImportMeta), "Containing file is missing import meta node flag."); + return node.name.escapedText === "meta" ? getGlobalImportMetaType() : errorType; + } + + function getTypeOfParameter(symbol: Symbol) { + const declaration = symbol.valueDeclaration; + return addOptionality( + getTypeOfSymbol(symbol), + /*isProperty*/ false, + /*isOptional*/ !!declaration && (hasInitializer(declaration) || isOptionalDeclaration(declaration)), + ); + } + + function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember): __String; + function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember | undefined, index: number, restParameterName?: __String): __String; + function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember | undefined, index?: number, restParameterName = "arg" as __String) { + if (!d) { + return `${restParameterName}_${index}` as __String; + } + Debug.assert(isIdentifier(d.name)); // Parameter declarations could be binding patterns, but we only allow identifier names + return d.name.escapedText; + } + + function getParameterNameAtPosition(signature: Signature, pos: number, overrideRestType?: Type) { + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + return signature.parameters[pos].escapedName; + } + const restParameter = signature.parameters[paramCount] || unknownSymbol; + const restType = overrideRestType || getTypeOfSymbol(restParameter); + if (isTupleType(restType)) { + const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; + const index = pos - paramCount; + return getTupleElementLabel(associatedNames?.[index], index, restParameter.escapedName); + } + return restParameter.escapedName; + } + + function getParameterIdentifierInfoAtPosition(signature: Signature, pos: number): { parameter: Identifier; parameterName: __String; isRestParameter: boolean; } | undefined { + if (signature.declaration?.kind === SyntaxKind.JSDocFunctionType) { + return undefined; + } + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + const param = signature.parameters[pos]; + const paramIdent = getParameterDeclarationIdentifier(param); + return paramIdent ? { + parameter: paramIdent, + parameterName: param.escapedName, + isRestParameter: false, + } : undefined; + } + + const restParameter = signature.parameters[paramCount] || unknownSymbol; + const restIdent = getParameterDeclarationIdentifier(restParameter); + if (!restIdent) { + return undefined; + } + + const restType = getTypeOfSymbol(restParameter); + if (isTupleType(restType)) { + const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; + const index = pos - paramCount; + const associatedName = associatedNames?.[index]; + const isRestTupleElement = !!associatedName?.dotDotDotToken; + + if (associatedName) { + Debug.assert(isIdentifier(associatedName.name)); + return { parameter: associatedName.name, parameterName: associatedName.name.escapedText, isRestParameter: isRestTupleElement }; + } + + return undefined; + } + + if (pos === paramCount) { + return { parameter: restIdent, parameterName: restParameter.escapedName, isRestParameter: true }; + } + return undefined; + } + + function getParameterDeclarationIdentifier(symbol: Symbol) { + return symbol.valueDeclaration && isParameter(symbol.valueDeclaration) && isIdentifier(symbol.valueDeclaration.name) && symbol.valueDeclaration.name; + } + function isValidDeclarationForTupleLabel(d: Declaration): d is NamedTupleMember | (ParameterDeclaration & { name: Identifier; }) { + return d.kind === SyntaxKind.NamedTupleMember || (isParameter(d) && d.name && isIdentifier(d.name)); + } + + function getNameableDeclarationAtPosition(signature: Signature, pos: number) { + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + const decl = signature.parameters[pos].valueDeclaration; + return decl && isValidDeclarationForTupleLabel(decl) ? decl : undefined; + } + const restParameter = signature.parameters[paramCount] || unknownSymbol; + const restType = getTypeOfSymbol(restParameter); + if (isTupleType(restType)) { + const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; + const index = pos - paramCount; + return associatedNames && associatedNames[index]; + } + return restParameter.valueDeclaration && isValidDeclarationForTupleLabel(restParameter.valueDeclaration) ? restParameter.valueDeclaration : undefined; + } + + function getTypeAtPosition(signature: Signature, pos: number): Type { + return tryGetTypeAtPosition(signature, pos) || anyType; + } + + function tryGetTypeAtPosition(signature: Signature, pos: number): Type | undefined { + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + return getTypeOfParameter(signature.parameters[pos]); + } + if (signatureHasRestParameter(signature)) { + // We want to return the value undefined for an out of bounds parameter position, + // so we need to check bounds here before calling getIndexedAccessType (which + // otherwise would return the type 'undefined'). + const restType = getTypeOfSymbol(signature.parameters[paramCount]); + const index = pos - paramCount; + if (!isTupleType(restType) || restType.target.combinedFlags & ElementFlags.Variable || index < restType.target.fixedLength) { + return getIndexedAccessType(restType, getNumberLiteralType(index)); + } + } + return undefined; + } + + function getRestTypeAtPosition(source: Signature, pos: number, readonly?: boolean): Type { + const parameterCount = getParameterCount(source); + const minArgumentCount = getMinArgumentCount(source); + const restType = getEffectiveRestType(source); + if (restType && pos >= parameterCount - 1) { + return pos === parameterCount - 1 ? restType : createArrayType(getIndexedAccessType(restType, numberType)); + } + const types = []; + const flags = []; + const names = []; + for (let i = pos; i < parameterCount; i++) { + if (!restType || i < parameterCount - 1) { + types.push(getTypeAtPosition(source, i)); + flags.push(i < minArgumentCount ? ElementFlags.Required : ElementFlags.Optional); + } + else { + types.push(restType); + flags.push(ElementFlags.Variadic); + } + names.push(getNameableDeclarationAtPosition(source, i)); + } + return createTupleType(types, flags, readonly, names); + } + + // Return the rest type at the given position, transforming `any[]` into just `any`. We do this because + // in signatures we want `any[]` in a rest position to be compatible with anything, but `any[]` isn't + // assignable to tuple types with required elements. + function getRestOrAnyTypeAtPosition(source: Signature, pos: number): Type { + const restType = getRestTypeAtPosition(source, pos); + const elementType = restType && getElementTypeOfArrayType(restType); + return elementType && isTypeAny(elementType) ? anyType : restType; + } + + // Return the number of parameters in a signature. The rest parameter, if present, counts as one + // parameter. For example, the parameter count of (x: number, y: number, ...z: string[]) is 3 and + // the parameter count of (x: number, ...args: [number, ...string[], boolean])) is also 3. In the + // latter example, the effective rest type is [...string[], boolean]. + function getParameterCount(signature: Signature) { + const length = signature.parameters.length; + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[length - 1]); + if (isTupleType(restType)) { + return length + restType.target.fixedLength - (restType.target.combinedFlags & ElementFlags.Variable ? 0 : 1); + } + } + return length; + } + + function getMinArgumentCount(signature: Signature, flags?: MinArgumentCountFlags) { + const strongArityForUntypedJS = flags! & MinArgumentCountFlags.StrongArityForUntypedJS; + const voidIsNonOptional = flags! & MinArgumentCountFlags.VoidIsNonOptional; + if (voidIsNonOptional || signature.resolvedMinArgumentCount === undefined) { + let minArgumentCount: number | undefined; + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + if (isTupleType(restType)) { + const firstOptionalIndex = findIndex(restType.target.elementFlags, f => !(f & ElementFlags.Required)); + const requiredCount = firstOptionalIndex < 0 ? restType.target.fixedLength : firstOptionalIndex; + if (requiredCount > 0) { + minArgumentCount = signature.parameters.length - 1 + requiredCount; + } + } + } + if (minArgumentCount === undefined) { + if (!strongArityForUntypedJS && signature.flags & SignatureFlags.IsUntypedSignatureInJSFile) { + return 0; + } + minArgumentCount = signature.minArgumentCount; + } + if (voidIsNonOptional) { + return minArgumentCount; + } + for (let i = minArgumentCount - 1; i >= 0; i--) { + const type = getTypeAtPosition(signature, i); + if (filterType(type, acceptsVoid).flags & TypeFlags.Never) { + break; + } + minArgumentCount = i; + } + signature.resolvedMinArgumentCount = minArgumentCount; + } + return signature.resolvedMinArgumentCount; + } + + function hasEffectiveRestParameter(signature: Signature) { + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + return !isTupleType(restType) || !!(restType.target.combinedFlags & ElementFlags.Variable); + } + return false; + } + + function getEffectiveRestType(signature: Signature) { + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + if (!isTupleType(restType)) { + return isTypeAny(restType) ? anyArrayType : restType; + } + if (restType.target.combinedFlags & ElementFlags.Variable) { + return sliceTupleType(restType, restType.target.fixedLength); + } + } + return undefined; + } + + function getNonArrayRestType(signature: Signature) { + const restType = getEffectiveRestType(signature); + return restType && !isArrayType(restType) && !isTypeAny(restType) ? restType : undefined; + } + + function getTypeOfFirstParameterOfSignature(signature: Signature) { + return getTypeOfFirstParameterOfSignatureWithFallback(signature, neverType); + } + + function getTypeOfFirstParameterOfSignatureWithFallback(signature: Signature, fallbackType: Type) { + return signature.parameters.length > 0 ? getTypeAtPosition(signature, 0) : fallbackType; + } + + function inferFromAnnotatedParameters(signature: Signature, context: Signature, inferenceContext: InferenceContext) { + const len = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + for (let i = 0; i < len; i++) { + const declaration = signature.parameters[i].valueDeclaration as ParameterDeclaration; + const typeNode = getEffectiveTypeAnnotationNode(declaration); + if (typeNode) { + const source = addOptionality(getTypeFromTypeNode(typeNode), /*isProperty*/ false, isOptionalDeclaration(declaration)); + const target = getTypeAtPosition(context, i); + inferTypes(inferenceContext.inferences, source, target); + } + } + } + + function assignContextualParameterTypes(signature: Signature, context: Signature) { + if (context.typeParameters) { + if (!signature.typeParameters) { + signature.typeParameters = context.typeParameters; + } + else { + return; // This signature has already has a contextual inference performed and cached on it! + } + } + if (context.thisParameter) { + const parameter = signature.thisParameter; + if (!parameter || parameter.valueDeclaration && !(parameter.valueDeclaration as ParameterDeclaration).type) { + if (!parameter) { + signature.thisParameter = createSymbolWithType(context.thisParameter, /*type*/ undefined); + } + assignParameterType(signature.thisParameter!, getTypeOfSymbol(context.thisParameter)); + } + } + const len = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + for (let i = 0; i < len; i++) { + const parameter = signature.parameters[i]; + const declaration = parameter.valueDeclaration as ParameterDeclaration; + if (!getEffectiveTypeAnnotationNode(declaration)) { + let type = tryGetTypeAtPosition(context, i); + if (type && declaration.initializer) { + let initializerType = checkDeclarationInitializer(declaration, CheckMode.Normal); + if (!isTypeAssignableTo(initializerType, type) && isTypeAssignableTo(type, initializerType = widenTypeInferredFromInitializer(declaration, initializerType))) { + type = initializerType; + } + } + assignParameterType(parameter, type); + } + } + if (signatureHasRestParameter(signature)) { + // parameter might be a transient symbol generated by use of `arguments` in the function body. + const parameter = last(signature.parameters); + if ( + parameter.valueDeclaration + ? !getEffectiveTypeAnnotationNode(parameter.valueDeclaration as ParameterDeclaration) + // a declarationless parameter may still have a `.type` already set by its construction logic + // (which may pull a type from a jsdoc) - only allow fixing on `DeferredType` parameters with a fallback type + : !!(getCheckFlags(parameter) & CheckFlags.DeferredType) + ) { + const contextualParameterType = getRestTypeAtPosition(context, len); + assignParameterType(parameter, contextualParameterType); + } + } + } + + function assignNonContextualParameterTypes(signature: Signature) { + if (signature.thisParameter) { + assignParameterType(signature.thisParameter); + } + for (const parameter of signature.parameters) { + assignParameterType(parameter); + } + } + + function assignParameterType(parameter: Symbol, contextualType?: Type) { + const links = getSymbolLinks(parameter); + if (!links.type) { + const declaration = parameter.valueDeclaration as ParameterDeclaration | undefined; + links.type = addOptionality( + contextualType || (declaration ? getWidenedTypeForVariableLikeDeclaration(declaration, /*reportErrors*/ true) : getTypeOfSymbol(parameter)), + /*isProperty*/ false, + /*isOptional*/ !!declaration && !declaration.initializer && isOptionalDeclaration(declaration), + ); + if (declaration && declaration.name.kind !== SyntaxKind.Identifier) { + // if inference didn't come up with anything but unknown, fall back to the binding pattern if present. + if (links.type === unknownType) { + links.type = getTypeFromBindingPattern(declaration.name); + } + assignBindingElementTypes(declaration.name, links.type); + } + } + else if (contextualType) { + Debug.assertEqual(links.type, contextualType, "Parameter symbol already has a cached type which differs from newly assigned type"); + } + } + + // When contextual typing assigns a type to a parameter that contains a binding pattern, we also need to push + // the destructured type into the contained binding elements. + function assignBindingElementTypes(pattern: BindingPattern, parentType: Type) { + for (const element of pattern.elements) { + if (!isOmittedExpression(element)) { + const type = getBindingElementTypeFromParentType(element, parentType, /*noTupleBoundsCheck*/ false); + if (element.name.kind === SyntaxKind.Identifier) { + getSymbolLinks(getSymbolOfDeclaration(element)).type = type; + } + else { + assignBindingElementTypes(element.name, type); + } + } + } + } + + function createClassDecoratorContextType(classType: Type) { + return tryCreateTypeReference(getGlobalClassDecoratorContextType(/*reportErrors*/ true), [classType]); + } + + function createClassMethodDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassMethodDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassGetterDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassGetterDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassSetterDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassSetterDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassAccessorDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassAccessorDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassFieldDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassFieldDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + /** + * Gets a type like `{ name: "foo", private: false, static: true }` that is used to provided member-specific + * details that will be intersected with a decorator context type. + */ + function getClassMemberDecoratorContextOverrideType(nameType: Type, isPrivate: boolean, isStatic: boolean) { + const key = `${isPrivate ? "p" : "P"}${isStatic ? "s" : "S"}${nameType.id}` as const; + let overrideType = decoratorContextOverrideTypeCache.get(key); + if (!overrideType) { + const members = createSymbolTable(); + members.set("name" as __String, createProperty("name" as __String, nameType)); + members.set("private" as __String, createProperty("private" as __String, isPrivate ? trueType : falseType)); + members.set("static" as __String, createProperty("static" as __String, isStatic ? trueType : falseType)); + overrideType = createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, emptyArray); + decoratorContextOverrideTypeCache.set(key, overrideType); + } + return overrideType; + } + + function createClassMemberDecoratorContextTypeForNode(node: MethodDeclaration | AccessorDeclaration | PropertyDeclaration, thisType: Type, valueType: Type) { + const isStatic = hasStaticModifier(node); + const isPrivate = isPrivateIdentifier(node.name); + const nameType = isPrivate ? getStringLiteralType(idText(node.name)) : getLiteralTypeFromPropertyName(node.name); + const contextType = isMethodDeclaration(node) ? createClassMethodDecoratorContextType(thisType, valueType) : + isGetAccessorDeclaration(node) ? createClassGetterDecoratorContextType(thisType, valueType) : + isSetAccessorDeclaration(node) ? createClassSetterDecoratorContextType(thisType, valueType) : + isAutoAccessorPropertyDeclaration(node) ? createClassAccessorDecoratorContextType(thisType, valueType) : + isPropertyDeclaration(node) ? createClassFieldDecoratorContextType(thisType, valueType) : + Debug.failBadSyntaxKind(node); + const overrideType = getClassMemberDecoratorContextOverrideType(nameType, isPrivate, isStatic); + return getIntersectionType([contextType, overrideType]); + } + + function createClassAccessorDecoratorTargetType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassAccessorDecoratorTargetType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassAccessorDecoratorResultType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassAccessorDecoratorResultType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassFieldDecoratorInitializerMutatorType(thisType: Type, valueType: Type) { + const thisParam = createParameter("this" as __String, thisType); + const valueParam = createParameter("value" as __String, valueType); + return createFunctionType(/*typeParameters*/ undefined, thisParam, [valueParam], valueType, /*typePredicate*/ undefined, 1); + } + + /** + * Creates a call signature for an ES Decorator. This method is used by the semantics of + * `getESDecoratorCallSignature`, which you should probably be using instead. + */ + function createESDecoratorCallSignature(targetType: Type, contextType: Type, nonOptionalReturnType: Type) { + const targetParam = createParameter("target" as __String, targetType); + const contextParam = createParameter("context" as __String, contextType); + const returnType = getUnionType([nonOptionalReturnType, voidType]); + return createCallSignature(/*typeParameters*/ undefined, /*thisParameter*/ undefined, [targetParam, contextParam], returnType); + } + + /** + * Gets a call signature that should be used when resolving `decorator` as a call. This does not use the value + * of the decorator itself, but instead uses the declaration on which it is placed along with its relative + * position amongst other decorators on the same declaration to determine the applicable signature. The + * resulting signature can be used for call resolution, inference, and contextual typing. + */ + function getESDecoratorCallSignature(decorator: Decorator) { + // We are considering a future change that would allow the type of a decorator to affect the type of the + // class and its members, such as a `@Stringify` decorator changing the type of a `number` field to `string`, or + // a `@Callable` decorator adding a call signature to a `class`. The type arguments for the various context + // types may eventually change to reflect such mutations. + // + // In some cases we describe such potential mutations as coming from a "prior decorator application". It is + // important to note that, while decorators are *evaluated* left to right, they are *applied* right to left + // to preserve f ৹ g -> f(g(x)) application order. In these cases, a "prior" decorator usually means the + // next decorator following this one in document order. + // + // The "original type" of a class or member is the type it was declared as, or the type we infer from + // initializers, before _any_ decorators are applied. + // + // The type of a class or member that is a result of a prior decorator application represents the + // "current type", i.e., the type for the declaration at the time the decorator is _applied_. + // + // The type of a class or member that is the result of the application of *all* relevant decorators is the + // "final type". + // + // Any decorator that allows mutation or replacement will also refer to an "input type" and an + // "output type". The "input type" corresponds to the "current type" of the declaration, while the + // "output type" will become either the "input type/current type" for a subsequent decorator application, + // or the "final type" for the decorated declaration. + // + // It is important to understand decorator application order as it relates to how the "current", "input", + // "output", and "final" types will be determined: + // + // @E2 @E1 class SomeClass { + // @A2 @A1 static f() {} + // @B2 @B1 g() {} + // @C2 @C1 static x; + // @D2 @D1 y; + // } + // + // Per [the specification][1], decorators are applied in the following order: + // + // 1. For each static method (incl. get/set methods and `accessor` fields), in document order: + // a. Apply each decorator for that method, in reverse order (`A1`, `A2`). + // 2. For each instance method (incl. get/set methods and `accessor` fields), in document order: + // a. Apply each decorator for that method, in reverse order (`B1`, `B2`). + // 3. For each static field (excl. auto-accessors), in document order: + // a. Apply each decorator for that field, in reverse order (`C1`, `C2`). + // 4. For each instance field (excl. auto-accessors), in document order: + // a. Apply each decorator for that field, in reverse order (`D1`, `D2`). + // 5. Apply each decorator for the class, in reverse order (`E1`, `E2`). + // + // As a result, "current" types at each decorator application are as follows: + // - For `A1`, the "current" types of the class and method are their "original" types. + // - For `A2`, the "current type" of the method is the "output type" of `A1`, and the "current type" of the + // class is the type of `SomeClass` where `f` is the "output type" of `A1`. This becomes the "final type" + // of `f`. + // - For `B1`, the "current type" of the method is its "original type", and the "current type" of the class + // is the type of `SomeClass` where `f` now has its "final type". + // - etc. + // + // [1]: https://arai-a.github.io/ecma262-compare/?pr=2417&id=sec-runtime-semantics-classdefinitionevaluation + // + // This seems complicated at first glance, but is not unlike our existing inference for functions: + // + // declare function pipe( + // original: Original, + // a1: (input: Original, context: Context) => A1, + // a2: (input: A1, context: Context) => A2, + // b1: (input: A2, context: Context) => B1, + // b2: (input: B1, context: Context) => B2, + // c1: (input: B2, context: Context) => C1, + // c2: (input: C1, context: Context) => C2, + // d1: (input: C2, context: Context) => D1, + // d2: (input: D1, context: Context) => D2, + // e1: (input: D2, context: Context) => E1, + // e2: (input: E1, context: Context) => E2, + // ): E2; + + // When a decorator is applied, it is passed two arguments: "target", which is a value representing the + // thing being decorated (constructors for classes, functions for methods/accessors, `undefined` for fields, + // and a `{ get, set }` object for auto-accessors), and "context", which is an object that provides + // reflection information about the decorated element, as well as the ability to add additional "extra" + // initializers. In most cases, the "target" argument corresponds to the "input type" in some way, and the + // return value similarly corresponds to the "output type" (though if the "output type" is `void` or + // `undefined` then the "output type" is the "input type"). + + const { parent } = decorator; + const links = getNodeLinks(parent); + if (!links.decoratorSignature) { + links.decoratorSignature = anySignature; + switch (parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: { + // Class decorators have a `context` of `ClassDecoratorContext`, where the `Class` type + // argument will be the "final type" of the class after all decorators are applied. + + const node = parent as ClassDeclaration | ClassExpression; + const targetType = getTypeOfSymbol(getSymbolOfDeclaration(node)); + const contextType = createClassDecoratorContextType(targetType); + links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, targetType); + break; + } + + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: { + const node = parent as MethodDeclaration | GetAccessorDeclaration | SetAccessorDeclaration; + if (!isClassLike(node.parent)) break; + + // Method decorators have a `context` of `ClassMethodDecoratorContext`, where the + // `Value` type argument corresponds to the "final type" of the method. + // + // Getter decorators have a `context` of `ClassGetterDecoratorContext`, where the + // `Value` type argument corresponds to the "final type" of the value returned by the getter. + // + // Setter decorators have a `context` of `ClassSetterDecoratorContext`, where the + // `Value` type argument corresponds to the "final type" of the parameter of the setter. + // + // In all three cases, the `This` type argument is the "final type" of either the class or + // instance, depending on whether the member was `static`. + + const valueType = isMethodDeclaration(node) ? getOrCreateTypeFromSignature(getSignatureFromDeclaration(node)) : + getTypeOfNode(node); + + const thisType = hasStaticModifier(node) ? + getTypeOfSymbol(getSymbolOfDeclaration(node.parent)) : + getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node.parent)); + + // We wrap the "input type", if necessary, to match the decoration target. For getters this is + // something like `() => inputType`, for setters it's `(value: inputType) => void` and for + // methods it is just the input type. + const targetType = isGetAccessorDeclaration(node) ? createGetterFunctionType(valueType) : + isSetAccessorDeclaration(node) ? createSetterFunctionType(valueType) : + valueType; + + const contextType = createClassMemberDecoratorContextTypeForNode(node, thisType, valueType); + + // We also wrap the "output type", as needed. + const returnType = isGetAccessorDeclaration(node) ? createGetterFunctionType(valueType) : + isSetAccessorDeclaration(node) ? createSetterFunctionType(valueType) : + valueType; + + links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, returnType); + break; + } + + case SyntaxKind.PropertyDeclaration: { + const node = parent as PropertyDeclaration; + if (!isClassLike(node.parent)) break; + + // Field decorators have a `context` of `ClassFieldDecoratorContext` and + // auto-accessor decorators have a `context` of `ClassAccessorDecoratorContext. In + // both cases, the `This` type argument is the "final type" of either the class or instance, + // depending on whether the member was `static`, and the `Value` type argument corresponds to + // the "final type" of the value stored in the field. + + const valueType = getTypeOfNode(node); + const thisType = hasStaticModifier(node) ? + getTypeOfSymbol(getSymbolOfDeclaration(node.parent)) : + getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node.parent)); + + // The `target` of an auto-accessor decorator is a `{ get, set }` object, representing the + // runtime-generated getter and setter that are added to the class/prototype. The `target` of a + // regular field decorator is always `undefined` as it isn't installed until it is initialized. + const targetType = hasAccessorModifier(node) ? createClassAccessorDecoratorTargetType(thisType, valueType) : + undefinedType; + + const contextType = createClassMemberDecoratorContextTypeForNode(node, thisType, valueType); + + // We wrap the "output type" depending on the declaration. For auto-accessors, we wrap the + // "output type" in a `ClassAccessorDecoratorResult` type, which allows for + // mutation of the runtime-generated getter and setter, as well as the injection of an + // initializer mutator. For regular fields, we wrap the "output type" in an initializer mutator. + const returnType = hasAccessorModifier(node) ? createClassAccessorDecoratorResultType(thisType, valueType) : + createClassFieldDecoratorInitializerMutatorType(thisType, valueType); + + links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, returnType); + break; + } + } + } + return links.decoratorSignature === anySignature ? undefined : links.decoratorSignature; + } + + function getLegacyDecoratorCallSignature(decorator: Decorator) { + const { parent } = decorator; + const links = getNodeLinks(parent); + if (!links.decoratorSignature) { + links.decoratorSignature = anySignature; + switch (parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: { + const node = parent as ClassDeclaration | ClassExpression; + // For a class decorator, the `target` is the type of the class (e.g. the + // "static" or "constructor" side of the class). + const targetType = getTypeOfSymbol(getSymbolOfDeclaration(node)); + const targetParam = createParameter("target" as __String, targetType); + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam], + getUnionType([targetType, voidType]), + ); + break; + } + case SyntaxKind.Parameter: { + const node = parent as ParameterDeclaration; + if ( + !isConstructorDeclaration(node.parent) && + !(isMethodDeclaration(node.parent) || isSetAccessorDeclaration(node.parent) && isClassLike(node.parent.parent)) + ) { + break; + } + + if (getThisParameter(node.parent) === node) { + break; + } + + const index = getThisParameter(node.parent) ? + node.parent.parameters.indexOf(node) - 1 : + node.parent.parameters.indexOf(node); + Debug.assert(index >= 0); + + // A parameter declaration decorator will have three arguments (see `ParameterDecorator` in + // core.d.ts). + + const targetType = isConstructorDeclaration(node.parent) ? getTypeOfSymbol(getSymbolOfDeclaration(node.parent.parent)) : + getParentTypeOfClassElement(node.parent); + + const keyType = isConstructorDeclaration(node.parent) ? undefinedType : + getClassElementPropertyKeyType(node.parent); + + const indexType = getNumberLiteralType(index); + + const targetParam = createParameter("target" as __String, targetType); + const keyParam = createParameter("propertyKey" as __String, keyType); + const indexParam = createParameter("parameterIndex" as __String, indexType); + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam, keyParam, indexParam], + voidType, + ); + break; + } + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.PropertyDeclaration: { + const node = parent as MethodDeclaration | AccessorDeclaration | PropertyDeclaration; + if (!isClassLike(node.parent)) break; + + // A method or accessor declaration decorator will have either two or three arguments (see + // `PropertyDecorator` and `MethodDecorator` in core.d.ts). + + const targetType = getParentTypeOfClassElement(node); + const targetParam = createParameter("target" as __String, targetType); + + const keyType = getClassElementPropertyKeyType(node); + const keyParam = createParameter("propertyKey" as __String, keyType); + + const returnType = isPropertyDeclaration(node) ? voidType : + createTypedPropertyDescriptorType(getTypeOfNode(node)); + + const hasPropDesc = !isPropertyDeclaration(parent) || hasAccessorModifier(parent); + if (hasPropDesc) { + const descriptorType = createTypedPropertyDescriptorType(getTypeOfNode(node)); + const descriptorParam = createParameter("descriptor" as __String, descriptorType); + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam, keyParam, descriptorParam], + getUnionType([returnType, voidType]), + ); + } + else { + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam, keyParam], + getUnionType([returnType, voidType]), + ); + } + break; + } + } + } + return links.decoratorSignature === anySignature ? undefined : links.decoratorSignature; + } + + function getDecoratorCallSignature(decorator: Decorator) { + return legacyDecorators ? getLegacyDecoratorCallSignature(decorator) : + getESDecoratorCallSignature(decorator); + } + + function createPromiseType(promisedType: Type): Type { + // creates a `Promise` type where `T` is the promisedType argument + const globalPromiseType = getGlobalPromiseType(/*reportErrors*/ true); + if (globalPromiseType !== emptyGenericType) { + // if the promised type is itself a promise, get the underlying type; otherwise, fallback to the promised type + // Unwrap an `Awaited` to `T` to improve inference. + promisedType = getAwaitedTypeNoAlias(unwrapAwaitedType(promisedType)) || unknownType; + return createTypeReference(globalPromiseType, [promisedType]); + } + + return unknownType; + } + + function createPromiseLikeType(promisedType: Type): Type { + // creates a `PromiseLike` type where `T` is the promisedType argument + const globalPromiseLikeType = getGlobalPromiseLikeType(/*reportErrors*/ true); + if (globalPromiseLikeType !== emptyGenericType) { + // if the promised type is itself a promise, get the underlying type; otherwise, fallback to the promised type + // Unwrap an `Awaited` to `T` to improve inference. + promisedType = getAwaitedTypeNoAlias(unwrapAwaitedType(promisedType)) || unknownType; + return createTypeReference(globalPromiseLikeType, [promisedType]); + } + + return unknownType; + } + + function createPromiseReturnType(func: FunctionLikeDeclaration | ImportCall, promisedType: Type) { + const promiseType = createPromiseType(promisedType); + if (promiseType === unknownType) { + error( + func, + isImportCall(func) ? + Diagnostics.A_dynamic_import_call_returns_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option : + Diagnostics.An_async_function_or_method_must_return_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option, + ); + return errorType; + } + else if (!getGlobalPromiseConstructorSymbol(/*reportErrors*/ true)) { + error( + func, + isImportCall(func) ? + Diagnostics.A_dynamic_import_call_in_ES5_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option : + Diagnostics.An_async_function_or_method_in_ES5_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option, + ); + } + + return promiseType; + } + + function createNewTargetExpressionType(targetType: Type): Type { + // Create a synthetic type `NewTargetExpression { target: TargetType; }` + const symbol = createSymbol(SymbolFlags.None, "NewTargetExpression" as __String); + + const targetPropertySymbol = createSymbol(SymbolFlags.Property, "target" as __String, CheckFlags.Readonly); + targetPropertySymbol.parent = symbol; + targetPropertySymbol.links.type = targetType; + + const members = createSymbolTable([targetPropertySymbol]); + symbol.members = members; + return createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + } + + function getReturnTypeFromBody(func: FunctionLikeDeclaration, checkMode?: CheckMode): Type { + if (!func.body) { + return errorType; + } + + const functionFlags = getFunctionFlags(func); + const isAsync = (functionFlags & FunctionFlags.Async) !== 0; + const isGenerator = (functionFlags & FunctionFlags.Generator) !== 0; + + let returnType: Type | undefined; + let yieldType: Type | undefined; + let nextType: Type | undefined; + let fallbackReturnType: Type = voidType; + if (func.body.kind !== SyntaxKind.Block) { // Async or normal arrow function + returnType = checkExpressionCached(func.body, checkMode && checkMode & ~CheckMode.SkipGenericFunctions); + if (isAsync) { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so the + // return type of the body should be unwrapped to its awaited type, which we will wrap in + // the native Promise type later in this function. + returnType = unwrapAwaitedType(checkAwaitedType(returnType, /*withAlias*/ false, /*errorNode*/ func, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member)); + } + } + else if (isGenerator) { // Generator or AsyncGenerator function + const returnTypes = checkAndAggregateReturnExpressionTypes(func, checkMode); + if (!returnTypes) { + fallbackReturnType = neverType; + } + else if (returnTypes.length > 0) { + returnType = getUnionType(returnTypes, UnionReduction.Subtype); + } + const { yieldTypes, nextTypes } = checkAndAggregateYieldOperandTypes(func, checkMode); + yieldType = some(yieldTypes) ? getUnionType(yieldTypes, UnionReduction.Subtype) : undefined; + nextType = some(nextTypes) ? getIntersectionType(nextTypes) : undefined; + } + else { // Async or normal function + const types = checkAndAggregateReturnExpressionTypes(func, checkMode); + if (!types) { + // For an async function, the return type will not be never, but rather a Promise for never. + return functionFlags & FunctionFlags.Async + ? createPromiseReturnType(func, neverType) // Async function + : neverType; // Normal function + } + if (types.length === 0) { + // For an async function, the return type will not be void/undefined, but rather a Promise for void/undefined. + const contextualReturnType = getContextualReturnType(func, /*contextFlags*/ undefined); + const returnType = contextualReturnType && (unwrapReturnType(contextualReturnType, functionFlags) || voidType).flags & TypeFlags.Undefined ? undefinedType : voidType; + return functionFlags & FunctionFlags.Async ? createPromiseReturnType(func, returnType) : // Async function + returnType; // Normal function + } + + // Return a union of the return expression types. + returnType = getUnionType(types, UnionReduction.Subtype); + } + + if (returnType || yieldType || nextType) { + if (yieldType) reportErrorsFromWidening(func, yieldType, WideningKind.GeneratorYield); + if (returnType) reportErrorsFromWidening(func, returnType, WideningKind.FunctionReturn); + if (nextType) reportErrorsFromWidening(func, nextType, WideningKind.GeneratorNext); + if ( + returnType && isUnitType(returnType) || + yieldType && isUnitType(yieldType) || + nextType && isUnitType(nextType) + ) { + const contextualSignature = getContextualSignatureForFunctionLikeDeclaration(func); + const contextualType = !contextualSignature ? undefined : + contextualSignature === getSignatureFromDeclaration(func) ? isGenerator ? undefined : returnType : + instantiateContextualType(getReturnTypeOfSignature(contextualSignature), func, /*contextFlags*/ undefined); + if (isGenerator) { + yieldType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(yieldType, contextualType, IterationTypeKind.Yield, isAsync); + returnType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(returnType, contextualType, IterationTypeKind.Return, isAsync); + nextType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(nextType, contextualType, IterationTypeKind.Next, isAsync); + } + else { + returnType = getWidenedLiteralLikeTypeForContextualReturnTypeIfNeeded(returnType, contextualType, isAsync); + } + } + + if (yieldType) yieldType = getWidenedType(yieldType); + if (returnType) returnType = getWidenedType(returnType); + if (nextType) nextType = getWidenedType(nextType); + } + + if (isGenerator) { + return createGeneratorType( + yieldType || neverType, + returnType || fallbackReturnType, + nextType || getContextualIterationType(IterationTypeKind.Next, func) || unknownType, + isAsync, + ); + } + else { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so the + // return type of the body is awaited type of the body, wrapped in a native Promise type. + return isAsync + ? createPromiseType(returnType || fallbackReturnType) + : returnType || fallbackReturnType; + } + } + + function createGeneratorType(yieldType: Type, returnType: Type, nextType: Type, isAsyncGenerator: boolean) { + const resolver = isAsyncGenerator ? asyncIterationTypesResolver : syncIterationTypesResolver; + const globalGeneratorType = resolver.getGlobalGeneratorType(/*reportErrors*/ false); + yieldType = resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || unknownType; + returnType = resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || unknownType; + nextType = resolver.resolveIterationType(nextType, /*errorNode*/ undefined) || unknownType; + if (globalGeneratorType === emptyGenericType) { + // Fall back to the global IterableIterator if returnType is assignable to the expected return iteration + // type of IterableIterator, and the expected next iteration type of IterableIterator is assignable to + // nextType. + const globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false); + const iterationTypes = globalType !== emptyGenericType ? getIterationTypesOfGlobalIterableType(globalType, resolver) : undefined; + const iterableIteratorReturnType = iterationTypes ? iterationTypes.returnType : anyType; + const iterableIteratorNextType = iterationTypes ? iterationTypes.nextType : undefinedType; + if ( + isTypeAssignableTo(returnType, iterableIteratorReturnType) && + isTypeAssignableTo(iterableIteratorNextType, nextType) + ) { + if (globalType !== emptyGenericType) { + return createTypeFromGenericGlobalType(globalType, [yieldType]); + } + + // The global IterableIterator type doesn't exist, so report an error + resolver.getGlobalIterableIteratorType(/*reportErrors*/ true); + return emptyObjectType; + } + + // The global Generator type doesn't exist, so report an error + resolver.getGlobalGeneratorType(/*reportErrors*/ true); + return emptyObjectType; + } + + return createTypeFromGenericGlobalType(globalGeneratorType, [yieldType, returnType, nextType]); + } + + function checkAndAggregateYieldOperandTypes(func: FunctionLikeDeclaration, checkMode: CheckMode | undefined) { + const yieldTypes: Type[] = []; + const nextTypes: Type[] = []; + const isAsync = (getFunctionFlags(func) & FunctionFlags.Async) !== 0; + forEachYieldExpression(func.body as Block, yieldExpression => { + const yieldExpressionType = yieldExpression.expression ? checkExpression(yieldExpression.expression, checkMode) : undefinedWideningType; + pushIfUnique(yieldTypes, getYieldedTypeOfYieldExpression(yieldExpression, yieldExpressionType, anyType, isAsync)); + let nextType: Type | undefined; + if (yieldExpression.asteriskToken) { + const iterationTypes = getIterationTypesOfIterable( + yieldExpressionType, + isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar, + yieldExpression.expression, + ); + nextType = iterationTypes && iterationTypes.nextType; + } + else { + nextType = getContextualType(yieldExpression, /*contextFlags*/ undefined); + } + if (nextType) pushIfUnique(nextTypes, nextType); + }); + return { yieldTypes, nextTypes }; + } + + function getYieldedTypeOfYieldExpression(node: YieldExpression, expressionType: Type, sentType: Type, isAsync: boolean): Type | undefined { + const errorNode = node.expression || node; + // A `yield*` expression effectively yields everything that its operand yields + const yieldedType = node.asteriskToken ? checkIteratedTypeOrElementType(isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar, expressionType, sentType, errorNode) : expressionType; + return !isAsync ? yieldedType : getAwaitedType( + yieldedType, + errorNode, + node.asteriskToken + ? Diagnostics.Type_of_iterated_elements_of_a_yield_Asterisk_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member + : Diagnostics.Type_of_yield_operand_in_an_async_generator_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member, + ); + } + + // Return the combined not-equal type facts for all cases except those between the start and end indices. + function getNotEqualFactsFromTypeofSwitch(start: number, end: number, witnesses: (string | undefined)[]): TypeFacts { + let facts: TypeFacts = TypeFacts.None; + for (let i = 0; i < witnesses.length; i++) { + const witness = i < start || i >= end ? witnesses[i] : undefined; + facts |= witness !== undefined ? typeofNEFacts.get(witness) || TypeFacts.TypeofNEHostObject : 0; + } + return facts; + } + + function isExhaustiveSwitchStatement(node: SwitchStatement): boolean { + const links = getNodeLinks(node); + if (links.isExhaustive === undefined) { + links.isExhaustive = 0; // Indicate resolution is in process + const exhaustive = computeExhaustiveSwitchStatement(node); + if (links.isExhaustive === 0) { + links.isExhaustive = exhaustive; + } + } + else if (links.isExhaustive === 0) { + links.isExhaustive = false; // Resolve circularity to false + } + return links.isExhaustive; + } + + function computeExhaustiveSwitchStatement(node: SwitchStatement): boolean { + if (node.expression.kind === SyntaxKind.TypeOfExpression) { + const witnesses = getSwitchClauseTypeOfWitnesses(node); + if (!witnesses) { + return false; + } + const operandConstraint = getBaseConstraintOrType(checkExpressionCached((node.expression as TypeOfExpression).expression)); + // Get the not-equal flags for all handled cases. + const notEqualFacts = getNotEqualFactsFromTypeofSwitch(0, 0, witnesses); + if (operandConstraint.flags & TypeFlags.AnyOrUnknown) { + // We special case the top types to be exhaustive when all cases are handled. + return (TypeFacts.AllTypeofNE & notEqualFacts) === TypeFacts.AllTypeofNE; + } + // A missing not-equal flag indicates that the type wasn't handled by some case. + return !someType(operandConstraint, t => getTypeFacts(t, notEqualFacts) === notEqualFacts); + } + const type = checkExpressionCached(node.expression); + if (!isLiteralType(type)) { + return false; + } + const switchTypes = getSwitchClauseTypes(node); + if (!switchTypes.length || some(switchTypes, isNeitherUnitTypeNorNever)) { + return false; + } + return eachTypeContainedIn(mapType(type, getRegularTypeOfLiteralType), switchTypes); + } + + function functionHasImplicitReturn(func: FunctionLikeDeclaration) { + return func.endFlowNode && isReachableFlowNode(func.endFlowNode); + } + + /** NOTE: Return value of `[]` means a different thing than `undefined`. `[]` means func returns `void`, `undefined` means it returns `never`. */ + function checkAndAggregateReturnExpressionTypes(func: FunctionLikeDeclaration, checkMode: CheckMode | undefined): Type[] | undefined { + const functionFlags = getFunctionFlags(func); + const aggregatedTypes: Type[] = []; + let hasReturnWithNoExpression = functionHasImplicitReturn(func); + let hasReturnOfTypeNever = false; + forEachReturnStatement(func.body as Block, returnStatement => { + let expr = returnStatement.expression; + if (expr) { + expr = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + // Bare calls to this same function don't contribute to inference + // and `return await` is also safe to unwrap here + if (functionFlags & FunctionFlags.Async && expr.kind === SyntaxKind.AwaitExpression) { + expr = skipParentheses((expr as AwaitExpression).expression, /*excludeJSDocTypeAssertions*/ true); + } + if ( + expr.kind === SyntaxKind.CallExpression && + (expr as CallExpression).expression.kind === SyntaxKind.Identifier && + checkExpressionCached((expr as CallExpression).expression).symbol === getMergedSymbol(func.symbol) && + (!isFunctionExpressionOrArrowFunction(func.symbol.valueDeclaration!) || isConstantReference((expr as CallExpression).expression)) + ) { + hasReturnOfTypeNever = true; + return; + } + + let type = checkExpressionCached(expr, checkMode && checkMode & ~CheckMode.SkipGenericFunctions); + if (functionFlags & FunctionFlags.Async) { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so the + // return type of the body should be unwrapped to its awaited type, which should be wrapped in + // the native Promise type by the caller. + type = unwrapAwaitedType(checkAwaitedType(type, /*withAlias*/ false, func, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member)); + } + if (type.flags & TypeFlags.Never) { + hasReturnOfTypeNever = true; + } + pushIfUnique(aggregatedTypes, type); + } + else { + hasReturnWithNoExpression = true; + } + }); + if (aggregatedTypes.length === 0 && !hasReturnWithNoExpression && (hasReturnOfTypeNever || mayReturnNever(func))) { + return undefined; + } + if ( + strictNullChecks && aggregatedTypes.length && hasReturnWithNoExpression && + !(isJSConstructor(func) && aggregatedTypes.some(t => t.symbol === func.symbol)) + ) { + // Javascript "callable constructors", containing eg `if (!(this instanceof A)) return new A()` should not add undefined + pushIfUnique(aggregatedTypes, undefinedType); + } + return aggregatedTypes; + } + function mayReturnNever(func: FunctionLikeDeclaration): boolean { + switch (func.kind) { + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + return true; + case SyntaxKind.MethodDeclaration: + return func.parent.kind === SyntaxKind.ObjectLiteralExpression; + default: + return false; + } + } + + function getTypePredicateFromBody(func: FunctionLikeDeclaration): TypePredicate | undefined { + switch (func.kind) { + case SyntaxKind.Constructor: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return undefined; + } + const functionFlags = getFunctionFlags(func); + if (functionFlags !== FunctionFlags.Normal) return undefined; + + // Only attempt to infer a type predicate if there's exactly one return. + let singleReturn: Expression | undefined; + if (func.body && func.body.kind !== SyntaxKind.Block) { + singleReturn = func.body; // arrow function + } + else { + const bailedEarly = forEachReturnStatement(func.body as Block, returnStatement => { + if (singleReturn || !returnStatement.expression) return true; + singleReturn = returnStatement.expression; + }); + if (bailedEarly || !singleReturn || functionHasImplicitReturn(func)) return undefined; + } + return checkIfExpressionRefinesAnyParameter(func, singleReturn); + } + + function checkIfExpressionRefinesAnyParameter(func: FunctionLikeDeclaration, expr: Expression): TypePredicate | undefined { + expr = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + const returnType = checkExpressionCached(expr); + if (!(returnType.flags & TypeFlags.Boolean)) return undefined; + + return forEach(func.parameters, (param, i) => { + const initType = getTypeOfSymbol(param.symbol); + if (!initType || initType.flags & TypeFlags.Boolean || !isIdentifier(param.name) || isSymbolAssigned(param.symbol) || isRestParameter(param)) { + // Refining "x: boolean" to "x is true" or "x is false" isn't useful. + return; + } + const trueType = checkIfExpressionRefinesParameter(func, expr, param, initType); + if (trueType) { + return createTypePredicate(TypePredicateKind.Identifier, unescapeLeadingUnderscores(param.name.escapedText), i, trueType); + } + }); + } + + function checkIfExpressionRefinesParameter(func: FunctionLikeDeclaration, expr: Expression, param: ParameterDeclaration, initType: Type): Type | undefined { + const antecedent = (expr as Expression & { flowNode?: FlowNode; }).flowNode || + expr.parent.kind === SyntaxKind.ReturnStatement && (expr.parent as ReturnStatement).flowNode || + createFlowNode(FlowFlags.Start, /*node*/ undefined, /*antecedent*/ undefined); + const trueCondition = createFlowNode(FlowFlags.TrueCondition, expr, antecedent); + + const trueType = getFlowTypeOfReference(param.name, initType, initType, func, trueCondition); + if (trueType === initType) return undefined; + + // "x is T" means that x is T if and only if it returns true. If it returns false then x is not T. + // This means that if the function is called with an argument of type trueType, there can't be anything left in the `else` branch. It must reduce to `never`. + const falseCondition = createFlowNode(FlowFlags.FalseCondition, expr, antecedent); + const falseSubtype = getFlowTypeOfReference(param.name, initType, trueType, func, falseCondition); + return falseSubtype.flags & TypeFlags.Never ? trueType : undefined; + } + + /** + * TypeScript Specification 1.0 (6.3) - July 2014 + * An explicitly typed function whose return type isn't the Void type, + * the Any type, or a union type containing the Void or Any type as a constituent + * must have at least one return statement somewhere in its body. + * An exception to this rule is if the function implementation consists of a single 'throw' statement. + * + * @param returnType - return type of the function, can be undefined if return type is not explicitly specified + */ + function checkAllCodePathsInNonVoidFunctionReturnOrThrow(func: FunctionLikeDeclaration | MethodSignature, returnType: Type | undefined) { + addLazyDiagnostic(checkAllCodePathsInNonVoidFunctionReturnOrThrowDiagnostics); + return; + + function checkAllCodePathsInNonVoidFunctionReturnOrThrowDiagnostics(): void { + const functionFlags = getFunctionFlags(func); + const type = returnType && unwrapReturnType(returnType, functionFlags); + + // Functions with an explicitly specified return type that includes `void` or is exactly `any` or `undefined` don't + // need any return statements. + if (type && (maybeTypeOfKind(type, TypeFlags.Void) || type.flags & (TypeFlags.Any | TypeFlags.Undefined))) { + return; + } + + // If all we have is a function signature, or an arrow function with an expression body, then there is nothing to check. + // also if HasImplicitReturn flag is not set this means that all codepaths in function body end with return or throw + if (func.kind === SyntaxKind.MethodSignature || nodeIsMissing(func.body) || func.body!.kind !== SyntaxKind.Block || !functionHasImplicitReturn(func)) { + return; + } + + const hasExplicitReturn = func.flags & NodeFlags.HasExplicitReturn; + const errorNode = getEffectiveReturnTypeNode(func) || func; + + if (type && type.flags & TypeFlags.Never) { + error(errorNode, Diagnostics.A_function_returning_never_cannot_have_a_reachable_end_point); + } + else if (type && !hasExplicitReturn) { + // minimal check: function has syntactic return type annotation and no explicit return statements in the body + // this function does not conform to the specification. + error(errorNode, Diagnostics.A_function_whose_declared_type_is_neither_undefined_void_nor_any_must_return_a_value); + } + else if (type && strictNullChecks && !isTypeAssignableTo(undefinedType, type)) { + error(errorNode, Diagnostics.Function_lacks_ending_return_statement_and_return_type_does_not_include_undefined); + } + else if (compilerOptions.noImplicitReturns) { + if (!type) { + // If return type annotation is omitted check if function has any explicit return statements. + // If it does not have any - its inferred return type is void - don't do any checks. + // Otherwise get inferred return type from function body and report error only if it is not void / anytype + if (!hasExplicitReturn) { + return; + } + const inferredReturnType = getReturnTypeOfSignature(getSignatureFromDeclaration(func)); + if (isUnwrappedReturnTypeUndefinedVoidOrAny(func, inferredReturnType)) { + return; + } + } + error(errorNode, Diagnostics.Not_all_code_paths_return_a_value); + } + } + } + + function checkFunctionExpressionOrObjectLiteralMethod(node: FunctionExpression | ArrowFunction | MethodDeclaration, checkMode?: CheckMode): Type { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + checkNodeDeferred(node); + + if (isFunctionExpression(node)) { + checkCollisionsForDeclarationName(node, node.name); + } + + // The identityMapper object is used to indicate that function expressions are wildcards + if (checkMode && checkMode & CheckMode.SkipContextSensitive && isContextSensitive(node)) { + // Skip parameters, return signature with return type that retains noncontextual parts so inferences can still be drawn in an early stage + if (!getEffectiveReturnTypeNode(node) && !hasContextSensitiveParameters(node)) { + // Return plain anyFunctionType if there is no possibility we'll make inferences from the return type + const contextualSignature = getContextualSignature(node); + if (contextualSignature && couldContainTypeVariables(getReturnTypeOfSignature(contextualSignature))) { + const links = getNodeLinks(node); + if (links.contextFreeType) { + return links.contextFreeType; + } + const returnType = getReturnTypeFromBody(node, checkMode); + const returnOnlySignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, returnType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.IsNonInferrable); + const returnOnlyType = createAnonymousType(node.symbol, emptySymbols, [returnOnlySignature], emptyArray, emptyArray); + returnOnlyType.objectFlags |= ObjectFlags.NonInferrableType; + return links.contextFreeType = returnOnlyType; + } + } + return anyFunctionType; + } + + // Grammar checking + const hasGrammarError = checkGrammarFunctionLikeDeclaration(node); + if (!hasGrammarError && node.kind === SyntaxKind.FunctionExpression) { + checkGrammarForGenerator(node); + } + + contextuallyCheckFunctionExpressionOrObjectLiteralMethod(node, checkMode); + + return getTypeOfSymbol(getSymbolOfDeclaration(node)); + } + + function contextuallyCheckFunctionExpressionOrObjectLiteralMethod(node: FunctionExpression | ArrowFunction | MethodDeclaration, checkMode?: CheckMode) { + const links = getNodeLinks(node); + // Check if function expression is contextually typed and assign parameter types if so. + if (!(links.flags & NodeCheckFlags.ContextChecked)) { + const contextualSignature = getContextualSignature(node); + // If a type check is started at a function expression that is an argument of a function call, obtaining the + // contextual type may recursively get back to here during overload resolution of the call. If so, we will have + // already assigned contextual types. + if (!(links.flags & NodeCheckFlags.ContextChecked)) { + links.flags |= NodeCheckFlags.ContextChecked; + const signature = firstOrUndefined(getSignaturesOfType(getTypeOfSymbol(getSymbolOfDeclaration(node)), SignatureKind.Call)); + if (!signature) { + return; + } + if (isContextSensitive(node)) { + if (contextualSignature) { + const inferenceContext = getInferenceContext(node); + let instantiatedContextualSignature: Signature | undefined; + if (checkMode && checkMode & CheckMode.Inferential) { + inferFromAnnotatedParameters(signature, contextualSignature, inferenceContext!); + const restType = getEffectiveRestType(contextualSignature); + if (restType && restType.flags & TypeFlags.TypeParameter) { + instantiatedContextualSignature = instantiateSignature(contextualSignature, inferenceContext!.nonFixingMapper); + } + } + instantiatedContextualSignature ||= inferenceContext ? + instantiateSignature(contextualSignature, inferenceContext.mapper) : contextualSignature; + assignContextualParameterTypes(signature, instantiatedContextualSignature); + } + else { + // Force resolution of all parameter types such that the absence of a contextual type is consistently reflected. + assignNonContextualParameterTypes(signature); + } + } + else if (contextualSignature && !node.typeParameters && contextualSignature.parameters.length > node.parameters.length) { + const inferenceContext = getInferenceContext(node); + if (checkMode && checkMode & CheckMode.Inferential) { + inferFromAnnotatedParameters(signature, contextualSignature, inferenceContext!); + } + } + if (contextualSignature && !getReturnTypeFromAnnotation(node) && !signature.resolvedReturnType) { + const returnType = getReturnTypeFromBody(node, checkMode); + if (!signature.resolvedReturnType) { + signature.resolvedReturnType = returnType; + } + } + checkSignatureDeclaration(node); + } + } + } + + function checkFunctionExpressionOrObjectLiteralMethodDeferred(node: ArrowFunction | FunctionExpression | MethodDeclaration) { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + + const functionFlags = getFunctionFlags(node); + const returnType = getReturnTypeFromAnnotation(node); + checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType); + + if (node.body) { + if (!getEffectiveReturnTypeNode(node)) { + // There are some checks that are only performed in getReturnTypeFromBody, that may produce errors + // we need. An example is the noImplicitAny errors resulting from widening the return expression + // of a function. Because checking of function expression bodies is deferred, there was never an + // appropriate time to do this during the main walk of the file (see the comment at the top of + // checkFunctionExpressionBodies). So it must be done now. + getReturnTypeOfSignature(getSignatureFromDeclaration(node)); + } + + if (node.body.kind === SyntaxKind.Block) { + checkSourceElement(node.body); + } + else { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so we + // should not be checking assignability of a promise to the return type. Instead, we need to + // check assignability of the awaited type of the expression body against the promised type of + // its return type annotation. + const exprType = checkExpression(node.body); + const returnOrPromisedType = returnType && unwrapReturnType(returnType, functionFlags); + if (returnOrPromisedType) { + const effectiveCheckNode = getEffectiveCheckNode(node.body); + if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async) { // Async function + const awaitedType = checkAwaitedType(exprType, /*withAlias*/ false, effectiveCheckNode, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); + checkTypeAssignableToAndOptionallyElaborate(awaitedType, returnOrPromisedType, effectiveCheckNode, effectiveCheckNode); + } + else { // Normal function + checkTypeAssignableToAndOptionallyElaborate(exprType, returnOrPromisedType, effectiveCheckNode, effectiveCheckNode); + } + } + } + } + } + + function checkArithmeticOperandType(operand: Node, type: Type, diagnostic: DiagnosticMessage, isAwaitValid = false): boolean { + if (!isTypeAssignableTo(type, numberOrBigIntType)) { + const awaitedType = isAwaitValid && getAwaitedTypeOfPromise(type); + errorAndMaybeSuggestAwait( + operand, + !!awaitedType && isTypeAssignableTo(awaitedType, numberOrBigIntType), + diagnostic, + ); + return false; + } + return true; + } + + function isReadonlyAssignmentDeclaration(d: Declaration) { + if (!isCallExpression(d)) { + return false; + } + if (!isBindableObjectDefinePropertyCall(d)) { + return false; + } + const objectLitType = checkExpressionCached(d.arguments[2]); + const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String); + if (valueType) { + const writableProp = getPropertyOfType(objectLitType, "writable" as __String); + const writableType = writableProp && getTypeOfSymbol(writableProp); + if (!writableType || writableType === falseType || writableType === regularFalseType) { + return true; + } + // We include this definition whereupon we walk back and check the type at the declaration because + // The usual definition of `Object.defineProperty` will _not_ cause literal types to be preserved in the + // argument types, should the type be contextualized by the call itself. + if (writableProp && writableProp.valueDeclaration && isPropertyAssignment(writableProp.valueDeclaration)) { + const initializer = writableProp.valueDeclaration.initializer; + const rawOriginalType = checkExpression(initializer); + if (rawOriginalType === falseType || rawOriginalType === regularFalseType) { + return true; + } + } + return false; + } + const setProp = getPropertyOfType(objectLitType, "set" as __String); + return !setProp; + } + + function isReadonlySymbol(symbol: Symbol): boolean { + // The following symbols are considered read-only: + // Properties with a 'readonly' modifier + // Variables declared with 'const' + // Get accessors without matching set accessors + // Enum members + // Object.defineProperty assignments with writable false or no setter + // Unions and intersections of the above (unions and intersections eagerly set isReadonly on creation) + return !!(getCheckFlags(symbol) & CheckFlags.Readonly || + symbol.flags & SymbolFlags.Property && getDeclarationModifierFlagsFromSymbol(symbol) & ModifierFlags.Readonly || + symbol.flags & SymbolFlags.Variable && getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Constant || + symbol.flags & SymbolFlags.Accessor && !(symbol.flags & SymbolFlags.SetAccessor) || + symbol.flags & SymbolFlags.EnumMember || + some(symbol.declarations, isReadonlyAssignmentDeclaration)); + } + + function isAssignmentToReadonlyEntity(expr: Expression, symbol: Symbol, assignmentKind: AssignmentKind) { + if (assignmentKind === AssignmentKind.None) { + // no assigment means it doesn't matter whether the entity is readonly + return false; + } + if (isReadonlySymbol(symbol)) { + // Allow assignments to readonly properties within constructors of the same class declaration. + if ( + symbol.flags & SymbolFlags.Property && + isAccessExpression(expr) && + expr.expression.kind === SyntaxKind.ThisKeyword + ) { + // Look for if this is the constructor for the class that `symbol` is a property of. + const ctor = getContainingFunction(expr); + if (!(ctor && (ctor.kind === SyntaxKind.Constructor || isJSConstructor(ctor)))) { + return true; + } + if (symbol.valueDeclaration) { + const isAssignmentDeclaration = isBinaryExpression(symbol.valueDeclaration); + const isLocalPropertyDeclaration = ctor.parent === symbol.valueDeclaration.parent; + const isLocalParameterProperty = ctor === symbol.valueDeclaration.parent; + const isLocalThisPropertyAssignment = isAssignmentDeclaration && symbol.parent?.valueDeclaration === ctor.parent; + const isLocalThisPropertyAssignmentConstructorFunction = isAssignmentDeclaration && symbol.parent?.valueDeclaration === ctor; + const isWriteableSymbol = isLocalPropertyDeclaration + || isLocalParameterProperty + || isLocalThisPropertyAssignment + || isLocalThisPropertyAssignmentConstructorFunction; + return !isWriteableSymbol; + } + } + return true; + } + if (isAccessExpression(expr)) { + // references through namespace import should be readonly + const node = skipParentheses(expr.expression); + if (node.kind === SyntaxKind.Identifier) { + const symbol = getNodeLinks(node).resolvedSymbol!; + if (symbol.flags & SymbolFlags.Alias) { + const declaration = getDeclarationOfAliasSymbol(symbol); + return !!declaration && declaration.kind === SyntaxKind.NamespaceImport; + } + } + } + return false; + } + + function checkReferenceExpression(expr: Expression, invalidReferenceMessage: DiagnosticMessage, invalidOptionalChainMessage: DiagnosticMessage): boolean { + // References are combinations of identifiers, parentheses, and property accesses. + const node = skipOuterExpressions(expr, OuterExpressionKinds.Assertions | OuterExpressionKinds.Parentheses); + if (node.kind !== SyntaxKind.Identifier && !isAccessExpression(node)) { + error(expr, invalidReferenceMessage); + return false; + } + if (node.flags & NodeFlags.OptionalChain) { + error(expr, invalidOptionalChainMessage); + return false; + } + return true; + } + + function checkDeleteExpression(node: DeleteExpression): Type { + checkExpression(node.expression); + const expr = skipParentheses(node.expression); + if (!isAccessExpression(expr)) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_must_be_a_property_reference); + return booleanType; + } + if (isPropertyAccessExpression(expr) && isPrivateIdentifier(expr.name)) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_cannot_be_a_private_identifier); + } + const links = getNodeLinks(expr); + const symbol = getExportSymbolOfValueSymbolIfExported(links.resolvedSymbol); + if (symbol) { + if (isReadonlySymbol(symbol)) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_cannot_be_a_read_only_property); + } + else { + checkDeleteExpressionMustBeOptional(expr, symbol); + } + } + return booleanType; + } + + function checkDeleteExpressionMustBeOptional(expr: AccessExpression, symbol: Symbol) { + const type = getTypeOfSymbol(symbol); + if ( + strictNullChecks && + !(type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Never)) && + !(exactOptionalPropertyTypes ? symbol.flags & SymbolFlags.Optional : hasTypeFacts(type, TypeFacts.IsUndefined)) + ) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_must_be_optional); + } + } + + function checkTypeOfExpression(node: TypeOfExpression): Type { + checkExpression(node.expression); + return typeofType; + } + + function checkVoidExpression(node: VoidExpression): Type { + checkNodeDeferred(node); + return undefinedWideningType; + } + + function checkAwaitGrammar(node: AwaitExpression | VariableDeclarationList): boolean { + // Grammar checking + let hasError = false; + const container = getContainingFunctionOrClassStaticBlock(node); + if (container && isClassStaticBlockDeclaration(container)) { + // NOTE: We report this regardless as to whether there are parse diagnostics. + const message = isAwaitExpression(node) ? Diagnostics.await_expression_cannot_be_used_inside_a_class_static_block : + Diagnostics.await_using_statements_cannot_be_used_inside_a_class_static_block; + error(node, message); + hasError = true; + } + else if (!(node.flags & NodeFlags.AwaitContext)) { + if (isInTopLevelContext(node)) { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + let span: TextSpan | undefined; + if (!isEffectiveExternalModule(sourceFile, compilerOptions)) { + span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); + const message = isAwaitExpression(node) ? Diagnostics.await_expressions_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module : + Diagnostics.await_using_statements_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module; + const diagnostic = createFileDiagnostic(sourceFile, span.start, span.length, message); + diagnostics.add(diagnostic); + hasError = true; + } + switch (moduleKind) { + case ModuleKind.Node16: + case ModuleKind.NodeNext: + if (sourceFile.impliedNodeFormat === ModuleKind.CommonJS) { + span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); + diagnostics.add( + createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.The_current_file_is_a_CommonJS_module_and_cannot_use_await_at_the_top_level), + ); + hasError = true; + break; + } + // fallthrough + case ModuleKind.ES2022: + case ModuleKind.ESNext: + case ModuleKind.Preserve: + case ModuleKind.System: + if (languageVersion >= ScriptTarget.ES2017) { + break; + } + // fallthrough + default: + span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); + const message = isAwaitExpression(node) ? Diagnostics.Top_level_await_expressions_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_nodenext_or_preserve_and_the_target_option_is_set_to_es2017_or_higher : + Diagnostics.Top_level_await_using_statements_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_nodenext_or_preserve_and_the_target_option_is_set_to_es2017_or_higher; + diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, message)); + hasError = true; + break; + } + } + } + else { + // use of 'await' in non-async function + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + const span = getSpanOfTokenAtPosition(sourceFile, node.pos); + const message = isAwaitExpression(node) ? Diagnostics.await_expressions_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules : + Diagnostics.await_using_statements_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules; + const diagnostic = createFileDiagnostic(sourceFile, span.start, span.length, message); + if (container && container.kind !== SyntaxKind.Constructor && (getFunctionFlags(container) & FunctionFlags.Async) === 0) { + const relatedInfo = createDiagnosticForNode(container, Diagnostics.Did_you_mean_to_mark_this_function_as_async); + addRelatedInfo(diagnostic, relatedInfo); + } + diagnostics.add(diagnostic); + hasError = true; + } + } + } + + if (isAwaitExpression(node) && isInParameterInitializerBeforeContainingFunction(node)) { + // NOTE: We report this regardless as to whether there are parse diagnostics. + error(node, Diagnostics.await_expressions_cannot_be_used_in_a_parameter_initializer); + hasError = true; + } + + return hasError; + } + + function checkAwaitExpression(node: AwaitExpression): Type { + addLazyDiagnostic(() => checkAwaitGrammar(node)); + + const operandType = checkExpression(node.expression); + const awaitedType = checkAwaitedType(operandType, /*withAlias*/ true, node, Diagnostics.Type_of_await_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); + if (awaitedType === operandType && !isErrorType(awaitedType) && !(operandType.flags & TypeFlags.AnyOrUnknown)) { + addErrorOrSuggestion(/*isError*/ false, createDiagnosticForNode(node, Diagnostics.await_has_no_effect_on_the_type_of_this_expression)); + } + return awaitedType; + } + + function checkPrefixUnaryExpression(node: PrefixUnaryExpression): Type { + const operandType = checkExpression(node.operand); + if (operandType === silentNeverType) { + return silentNeverType; + } + switch (node.operand.kind) { + case SyntaxKind.NumericLiteral: + switch (node.operator) { + case SyntaxKind.MinusToken: + return getFreshTypeOfLiteralType(getNumberLiteralType(-(node.operand as NumericLiteral).text)); + case SyntaxKind.PlusToken: + return getFreshTypeOfLiteralType(getNumberLiteralType(+(node.operand as NumericLiteral).text)); + } + break; + case SyntaxKind.BigIntLiteral: + if (node.operator === SyntaxKind.MinusToken) { + return getFreshTypeOfLiteralType(getBigIntLiteralType({ + negative: true, + base10Value: parsePseudoBigInt((node.operand as BigIntLiteral).text), + })); + } + } + switch (node.operator) { + case SyntaxKind.PlusToken: + case SyntaxKind.MinusToken: + case SyntaxKind.TildeToken: + checkNonNullType(operandType, node.operand); + if (maybeTypeOfKindConsideringBaseConstraint(operandType, TypeFlags.ESSymbolLike)) { + error(node.operand, Diagnostics.The_0_operator_cannot_be_applied_to_type_symbol, tokenToString(node.operator)); + } + if (node.operator === SyntaxKind.PlusToken) { + if (maybeTypeOfKindConsideringBaseConstraint(operandType, TypeFlags.BigIntLike)) { + error(node.operand, Diagnostics.Operator_0_cannot_be_applied_to_type_1, tokenToString(node.operator), typeToString(getBaseTypeOfLiteralType(operandType))); + } + return numberType; + } + return getUnaryResultType(operandType); + case SyntaxKind.ExclamationToken: + checkTruthinessOfType(operandType, node.operand); + const facts = getTypeFacts(operandType, TypeFacts.Truthy | TypeFacts.Falsy); + return facts === TypeFacts.Truthy ? falseType : + facts === TypeFacts.Falsy ? trueType : + booleanType; + case SyntaxKind.PlusPlusToken: + case SyntaxKind.MinusMinusToken: + const ok = checkArithmeticOperandType(node.operand, checkNonNullType(operandType, node.operand), Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type); + if (ok) { + // run check only if former checks succeeded to avoid reporting cascading errors + checkReferenceExpression( + node.operand, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access, + ); + } + return getUnaryResultType(operandType); + } + return errorType; + } + + function checkPostfixUnaryExpression(node: PostfixUnaryExpression): Type { + const operandType = checkExpression(node.operand); + if (operandType === silentNeverType) { + return silentNeverType; + } + const ok = checkArithmeticOperandType( + node.operand, + checkNonNullType(operandType, node.operand), + Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type, + ); + if (ok) { + // run check only if former checks succeeded to avoid reporting cascading errors + checkReferenceExpression( + node.operand, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access, + ); + } + return getUnaryResultType(operandType); + } + + function getUnaryResultType(operandType: Type): Type { + if (maybeTypeOfKind(operandType, TypeFlags.BigIntLike)) { + return isTypeAssignableToKind(operandType, TypeFlags.AnyOrUnknown) || maybeTypeOfKind(operandType, TypeFlags.NumberLike) + ? numberOrBigIntType + : bigintType; + } + // If it's not a bigint type, implicit coercion will result in a number + return numberType; + } + + function maybeTypeOfKindConsideringBaseConstraint(type: Type, kind: TypeFlags): boolean { + if (maybeTypeOfKind(type, kind)) { + return true; + } + + const baseConstraint = getBaseConstraintOrType(type); + return !!baseConstraint && maybeTypeOfKind(baseConstraint, kind); + } + + // Return true if type might be of the given kind. A union or intersection type might be of a given + // kind if at least one constituent type is of the given kind. + function maybeTypeOfKind(type: Type, kind: TypeFlags): boolean { + if (type.flags & kind) { + return true; + } + if (type.flags & TypeFlags.UnionOrIntersection) { + const types = (type as UnionOrIntersectionType).types; + for (const t of types) { + if (maybeTypeOfKind(t, kind)) { + return true; + } + } + } + return false; + } + + function isTypeAssignableToKind(source: Type, kind: TypeFlags, strict?: boolean): boolean { + if (source.flags & kind) { + return true; + } + if (strict && source.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Null)) { + return false; + } + return !!(kind & TypeFlags.NumberLike) && isTypeAssignableTo(source, numberType) || + !!(kind & TypeFlags.BigIntLike) && isTypeAssignableTo(source, bigintType) || + !!(kind & TypeFlags.StringLike) && isTypeAssignableTo(source, stringType) || + !!(kind & TypeFlags.BooleanLike) && isTypeAssignableTo(source, booleanType) || + !!(kind & TypeFlags.Void) && isTypeAssignableTo(source, voidType) || + !!(kind & TypeFlags.Never) && isTypeAssignableTo(source, neverType) || + !!(kind & TypeFlags.Null) && isTypeAssignableTo(source, nullType) || + !!(kind & TypeFlags.Undefined) && isTypeAssignableTo(source, undefinedType) || + !!(kind & TypeFlags.ESSymbol) && isTypeAssignableTo(source, esSymbolType) || + !!(kind & TypeFlags.NonPrimitive) && isTypeAssignableTo(source, nonPrimitiveType); + } + + function allTypesAssignableToKind(source: Type, kind: TypeFlags, strict?: boolean): boolean { + return source.flags & TypeFlags.Union ? + every((source as UnionType).types, subType => allTypesAssignableToKind(subType, kind, strict)) : + isTypeAssignableToKind(source, kind, strict); + } + + function isConstEnumObjectType(type: Type): boolean { + return !!(getObjectFlags(type) & ObjectFlags.Anonymous) && !!type.symbol && isConstEnumSymbol(type.symbol); + } + + function isConstEnumSymbol(symbol: Symbol): boolean { + return (symbol.flags & SymbolFlags.ConstEnum) !== 0; + } + + /** + * Get the type of the `[Symbol.hasInstance]` method of an object type. + */ + function getSymbolHasInstanceMethodOfObjectType(type: Type) { + const hasInstancePropertyName = getPropertyNameForKnownSymbolName("hasInstance"); + if (allTypesAssignableToKind(type, TypeFlags.NonPrimitive)) { + const hasInstanceProperty = getPropertyOfType(type, hasInstancePropertyName); + if (hasInstanceProperty) { + const hasInstancePropertyType = getTypeOfSymbol(hasInstanceProperty); + if (hasInstancePropertyType && getSignaturesOfType(hasInstancePropertyType, SignatureKind.Call).length !== 0) { + return hasInstancePropertyType; + } + } + } + } + + function checkInstanceOfExpression(left: Expression, right: Expression, leftType: Type, rightType: Type, checkMode?: CheckMode): Type { + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + + // TypeScript 1.0 spec (April 2014): 4.15.4 + // The instanceof operator requires the left operand to be of type Any, an object type, or a type parameter type, + // and the right operand to be of type Any, a subtype of the 'Function' interface type, or have a call or construct signature. + // The result is always of the Boolean primitive type. + // NOTE: do not raise error if leftType is unknown as related error was already reported + if ( + !isTypeAny(leftType) && + allTypesAssignableToKind(leftType, TypeFlags.Primitive) + ) { + error(left, Diagnostics.The_left_hand_side_of_an_instanceof_expression_must_be_of_type_any_an_object_type_or_a_type_parameter); + } + + Debug.assert(isInstanceOfExpression(left.parent)); + const signature = getResolvedSignature(left.parent, /*candidatesOutArray*/ undefined, checkMode); + if (signature === resolvingSignature) { + // CheckMode.SkipGenericFunctions is enabled and this is a call to a generic function that + // returns a function type. We defer checking and return silentNeverType. + return silentNeverType; + } + + // If rightType has a `[Symbol.hasInstance]` method that is not `(value: unknown) => boolean`, we + // must check the expression as if it were a call to `right[Symbol.hasInstance](left)`. The call to + // `getResolvedSignature`, below, will check that leftType is assignable to the type of the first + // parameter. + const returnType = getReturnTypeOfSignature(signature); + + // We also verify that the return type of the `[Symbol.hasInstance]` method is assignable to + // `boolean`. According to the spec, the runtime will actually perform `ToBoolean` on the result, + // but this is more type-safe. + checkTypeAssignableTo(returnType, booleanType, right, Diagnostics.An_object_s_Symbol_hasInstance_method_must_return_a_boolean_value_for_it_to_be_used_on_the_right_hand_side_of_an_instanceof_expression); + + return booleanType; + } + + function hasEmptyObjectIntersection(type: Type): boolean { + return someType(type, t => t === unknownEmptyObjectType || !!(t.flags & TypeFlags.Intersection) && isEmptyAnonymousObjectType(getBaseConstraintOrType(t))); + } + + function checkInExpression(left: Expression, right: Expression, leftType: Type, rightType: Type): Type { + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + if (isPrivateIdentifier(left)) { + if ( + languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators || + !useDefineForClassFields + ) { + checkExternalEmitHelpers(left, ExternalEmitHelpers.ClassPrivateFieldIn); + } + // Unlike in 'checkPrivateIdentifierExpression' we now have access to the RHS type + // which provides us with the opportunity to emit more detailed errors + if (!getNodeLinks(left).resolvedSymbol && getContainingClass(left)) { + const isUncheckedJS = isUncheckedJSSuggestion(left, rightType.symbol, /*excludeClasses*/ true); + reportNonexistentProperty(left, rightType, isUncheckedJS); + } + } + else { + // The type of the lef operand must be assignable to string, number, or symbol. + checkTypeAssignableTo(checkNonNullType(leftType, left), stringNumberSymbolType, left); + } + // The type of the right operand must be assignable to 'object'. + if (checkTypeAssignableTo(checkNonNullType(rightType, right), nonPrimitiveType, right)) { + // The {} type is assignable to the object type, yet {} might represent a primitive type. Here we + // detect and error on {} that results from narrowing the unknown type, as well as intersections + // that include {} (we know that the other types in such intersections are assignable to object + // since we already checked for that). + if (hasEmptyObjectIntersection(rightType)) { + error(right, Diagnostics.Type_0_may_represent_a_primitive_value_which_is_not_permitted_as_the_right_operand_of_the_in_operator, typeToString(rightType)); + } + } + // The result is always of the Boolean primitive type. + return booleanType; + } + + function checkObjectLiteralAssignment(node: ObjectLiteralExpression, sourceType: Type, rightIsThis?: boolean): Type { + const properties = node.properties; + if (strictNullChecks && properties.length === 0) { + return checkNonNullType(sourceType, node); + } + for (let i = 0; i < properties.length; i++) { + checkObjectLiteralDestructuringPropertyAssignment(node, sourceType, i, properties, rightIsThis); + } + return sourceType; + } + + /** Note: If property cannot be a SpreadAssignment, then allProperties does not need to be provided */ + function checkObjectLiteralDestructuringPropertyAssignment(node: ObjectLiteralExpression, objectLiteralType: Type, propertyIndex: number, allProperties?: NodeArray, rightIsThis = false) { + const properties = node.properties; + const property = properties[propertyIndex]; + if (property.kind === SyntaxKind.PropertyAssignment || property.kind === SyntaxKind.ShorthandPropertyAssignment) { + const name = property.name; + const exprType = getLiteralTypeFromPropertyName(name); + if (isTypeUsableAsPropertyName(exprType)) { + const text = getPropertyNameFromType(exprType); + const prop = getPropertyOfType(objectLiteralType, text); + if (prop) { + markPropertyAsReferenced(prop, property, rightIsThis); + checkPropertyAccessibility(property, /*isSuper*/ false, /*writing*/ true, objectLiteralType, prop); + } + } + const elementType = getIndexedAccessType(objectLiteralType, exprType, AccessFlags.ExpressionPosition, name); + const type = getFlowTypeOfDestructuring(property, elementType); + return checkDestructuringAssignment(property.kind === SyntaxKind.ShorthandPropertyAssignment ? property : property.initializer, type); + } + else if (property.kind === SyntaxKind.SpreadAssignment) { + if (propertyIndex < properties.length - 1) { + error(property, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); + } + else { + if (languageVersion < LanguageFeatureMinimumTarget.ObjectSpreadRest) { + checkExternalEmitHelpers(property, ExternalEmitHelpers.Rest); + } + const nonRestNames: PropertyName[] = []; + if (allProperties) { + for (const otherProperty of allProperties) { + if (!isSpreadAssignment(otherProperty)) { + nonRestNames.push(otherProperty.name); + } + } + } + const type = getRestType(objectLiteralType, nonRestNames, objectLiteralType.symbol); + checkGrammarForDisallowedTrailingComma(allProperties, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + return checkDestructuringAssignment(property.expression, type); + } + } + else { + error(property, Diagnostics.Property_assignment_expected); + } + } + + function checkArrayLiteralAssignment(node: ArrayLiteralExpression, sourceType: Type, checkMode?: CheckMode): Type { + const elements = node.elements; + if (languageVersion < LanguageFeatureMinimumTarget.DestructuringAssignment && compilerOptions.downlevelIteration) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Read); + } + // This elementType will be used if the specific property corresponding to this index is not + // present (aka the tuple element property). This call also checks that the parentType is in + // fact an iterable or array (depending on target language). + const possiblyOutOfBoundsType = checkIteratedTypeOrElementType(IterationUse.Destructuring | IterationUse.PossiblyOutOfBounds, sourceType, undefinedType, node) || errorType; + let inBoundsType: Type | undefined = compilerOptions.noUncheckedIndexedAccess ? undefined : possiblyOutOfBoundsType; + for (let i = 0; i < elements.length; i++) { + let type = possiblyOutOfBoundsType; + if (node.elements[i].kind === SyntaxKind.SpreadElement) { + type = inBoundsType = inBoundsType ?? (checkIteratedTypeOrElementType(IterationUse.Destructuring, sourceType, undefinedType, node) || errorType); + } + checkArrayLiteralDestructuringElementAssignment(node, sourceType, i, type, checkMode); + } + return sourceType; + } + + function checkArrayLiteralDestructuringElementAssignment(node: ArrayLiteralExpression, sourceType: Type, elementIndex: number, elementType: Type, checkMode?: CheckMode) { + const elements = node.elements; + const element = elements[elementIndex]; + if (element.kind !== SyntaxKind.OmittedExpression) { + if (element.kind !== SyntaxKind.SpreadElement) { + const indexType = getNumberLiteralType(elementIndex); + if (isArrayLikeType(sourceType)) { + // We create a synthetic expression so that getIndexedAccessType doesn't get confused + // when the element is a SyntaxKind.ElementAccessExpression. + const accessFlags = AccessFlags.ExpressionPosition | (hasDefaultValue(element) ? AccessFlags.NoTupleBoundsCheck : 0); + const elementType = getIndexedAccessTypeOrUndefined(sourceType, indexType, accessFlags, createSyntheticExpression(element, indexType)) || errorType; + const assignedType = hasDefaultValue(element) ? getTypeWithFacts(elementType, TypeFacts.NEUndefined) : elementType; + const type = getFlowTypeOfDestructuring(element, assignedType); + return checkDestructuringAssignment(element, type, checkMode); + } + return checkDestructuringAssignment(element, elementType, checkMode); + } + if (elementIndex < elements.length - 1) { + error(element, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); + } + else { + const restExpression = (element as SpreadElement).expression; + if (restExpression.kind === SyntaxKind.BinaryExpression && (restExpression as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) { + error((restExpression as BinaryExpression).operatorToken, Diagnostics.A_rest_element_cannot_have_an_initializer); + } + else { + checkGrammarForDisallowedTrailingComma(node.elements, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + const type = everyType(sourceType, isTupleType) ? + mapType(sourceType, t => sliceTupleType(t as TupleTypeReference, elementIndex)) : + createArrayType(elementType); + return checkDestructuringAssignment(restExpression, type, checkMode); + } + } + } + return undefined; + } + + function checkDestructuringAssignment(exprOrAssignment: Expression | ShorthandPropertyAssignment, sourceType: Type, checkMode?: CheckMode, rightIsThis?: boolean): Type { + let target: Expression; + if (exprOrAssignment.kind === SyntaxKind.ShorthandPropertyAssignment) { + const prop = exprOrAssignment as ShorthandPropertyAssignment; + if (prop.objectAssignmentInitializer) { + // In strict null checking mode, if a default value of a non-undefined type is specified, remove + // undefined from the final type. + if ( + strictNullChecks && + !(hasTypeFacts(checkExpression(prop.objectAssignmentInitializer), TypeFacts.IsUndefined)) + ) { + sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined); + } + checkBinaryLikeExpression(prop.name, prop.equalsToken!, prop.objectAssignmentInitializer, checkMode); + } + target = (exprOrAssignment as ShorthandPropertyAssignment).name; + } + else { + target = exprOrAssignment; + } + + if (target.kind === SyntaxKind.BinaryExpression && (target as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) { + checkBinaryExpression(target as BinaryExpression, checkMode); + target = (target as BinaryExpression).left; + // A default value is specified, so remove undefined from the final type. + if (strictNullChecks) { + sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined); + } + } + if (target.kind === SyntaxKind.ObjectLiteralExpression) { + return checkObjectLiteralAssignment(target as ObjectLiteralExpression, sourceType, rightIsThis); + } + if (target.kind === SyntaxKind.ArrayLiteralExpression) { + return checkArrayLiteralAssignment(target as ArrayLiteralExpression, sourceType, checkMode); + } + return checkReferenceAssignment(target, sourceType, checkMode); + } + + function checkReferenceAssignment(target: Expression, sourceType: Type, checkMode?: CheckMode): Type { + const targetType = checkExpression(target, checkMode); + const error = target.parent.kind === SyntaxKind.SpreadAssignment ? + Diagnostics.The_target_of_an_object_rest_assignment_must_be_a_variable_or_a_property_access : + Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access; + const optionalError = target.parent.kind === SyntaxKind.SpreadAssignment ? + Diagnostics.The_target_of_an_object_rest_assignment_may_not_be_an_optional_property_access : + Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access; + if (checkReferenceExpression(target, error, optionalError)) { + checkTypeAssignableToAndOptionallyElaborate(sourceType, targetType, target, target); + } + if (isPrivateIdentifierPropertyAccessExpression(target)) { + // NOTE: we do not limit this to LanguageFeatureTargets.PrivateNames as some other feature downleveling still requires this. + checkExternalEmitHelpers(target.parent, ExternalEmitHelpers.ClassPrivateFieldSet); + } + return sourceType; + } + + /** + * This is a *shallow* check: An expression is side-effect-free if the + * evaluation of the expression *itself* cannot produce side effects. + * For example, x++ / 3 is side-effect free because the / operator + * does not have side effects. + * The intent is to "smell test" an expression for correctness in positions where + * its value is discarded (e.g. the left side of the comma operator). + */ + function isSideEffectFree(node: Node): boolean { + node = skipParentheses(node); + switch (node.kind) { + case SyntaxKind.Identifier: + case SyntaxKind.StringLiteral: + case SyntaxKind.RegularExpressionLiteral: + case SyntaxKind.TaggedTemplateExpression: + case SyntaxKind.TemplateExpression: + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.NumericLiteral: + case SyntaxKind.BigIntLiteral: + case SyntaxKind.TrueKeyword: + case SyntaxKind.FalseKeyword: + case SyntaxKind.NullKeyword: + case SyntaxKind.UndefinedKeyword: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ClassExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.ArrayLiteralExpression: + case SyntaxKind.ObjectLiteralExpression: + case SyntaxKind.TypeOfExpression: + case SyntaxKind.NonNullExpression: + case SyntaxKind.JsxSelfClosingElement: + case SyntaxKind.JsxElement: + return true; + + case SyntaxKind.ConditionalExpression: + return isSideEffectFree((node as ConditionalExpression).whenTrue) && + isSideEffectFree((node as ConditionalExpression).whenFalse); + + case SyntaxKind.BinaryExpression: + if (isAssignmentOperator((node as BinaryExpression).operatorToken.kind)) { + return false; + } + return isSideEffectFree((node as BinaryExpression).left) && + isSideEffectFree((node as BinaryExpression).right); + + case SyntaxKind.PrefixUnaryExpression: + case SyntaxKind.PostfixUnaryExpression: + // Unary operators ~, !, +, and - have no side effects. + // The rest do. + switch ((node as PrefixUnaryExpression).operator) { + case SyntaxKind.ExclamationToken: + case SyntaxKind.PlusToken: + case SyntaxKind.MinusToken: + case SyntaxKind.TildeToken: + return true; + } + return false; + + // Some forms listed here for clarity + case SyntaxKind.VoidExpression: // Explicit opt-out + case SyntaxKind.TypeAssertionExpression: // Not SEF, but can produce useful type warnings + case SyntaxKind.AsExpression: // Not SEF, but can produce useful type warnings + default: + return false; + } + } + + function isTypeEqualityComparableTo(source: Type, target: Type) { + return (target.flags & TypeFlags.Nullable) !== 0 || isTypeComparableTo(source, target); + } + + function createCheckBinaryExpression() { + interface WorkArea { + readonly checkMode: CheckMode | undefined; + skip: boolean; + stackIndex: number; + /** + * Holds the types from the left-side of an expression from [0..stackIndex]. + * Holds the type of the result at stackIndex+1. This allows us to reuse existing stack entries + * and avoid storing an extra property on the object (i.e., `lastResult`). + */ + typeStack: (Type | undefined)[]; + } + + const trampoline = createBinaryExpressionTrampoline(onEnter, onLeft, onOperator, onRight, onExit, foldState); + + return (node: BinaryExpression, checkMode: CheckMode | undefined) => { + const result = trampoline(node, checkMode); + Debug.assertIsDefined(result); + return result; + }; + + function onEnter(node: BinaryExpression, state: WorkArea | undefined, checkMode: CheckMode | undefined) { + if (state) { + state.stackIndex++; + state.skip = false; + setLeftType(state, /*type*/ undefined); + setLastResult(state, /*type*/ undefined); + } + else { + state = { + checkMode, + skip: false, + stackIndex: 0, + typeStack: [undefined, undefined], + }; + } + + if (isInJSFile(node) && getAssignedExpandoInitializer(node)) { + state.skip = true; + setLastResult(state, checkExpression(node.right, checkMode)); + return state; + } + + checkGrammarNullishCoalesceWithLogicalExpression(node); + + const operator = node.operatorToken.kind; + if (operator === SyntaxKind.EqualsToken && (node.left.kind === SyntaxKind.ObjectLiteralExpression || node.left.kind === SyntaxKind.ArrayLiteralExpression)) { + state.skip = true; + setLastResult(state, checkDestructuringAssignment(node.left, checkExpression(node.right, checkMode), checkMode, node.right.kind === SyntaxKind.ThisKeyword)); + return state; + } + + return state; + } + + function onLeft(left: Expression, state: WorkArea, _node: BinaryExpression) { + if (!state.skip) { + return maybeCheckExpression(state, left); + } + } + + function onOperator(operatorToken: BinaryOperatorToken, state: WorkArea, node: BinaryExpression) { + if (!state.skip) { + const leftType = getLastResult(state); + Debug.assertIsDefined(leftType); + setLeftType(state, leftType); + setLastResult(state, /*type*/ undefined); + const operator = operatorToken.kind; + if (isLogicalOrCoalescingBinaryOperator(operator)) { + let parent = node.parent; + while (parent.kind === SyntaxKind.ParenthesizedExpression || isLogicalOrCoalescingBinaryExpression(parent)) { + parent = parent.parent; + } + if (operator === SyntaxKind.AmpersandAmpersandToken || isIfStatement(parent)) { + checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(node.left, leftType, isIfStatement(parent) ? parent.thenStatement : undefined); + } + checkTruthinessOfType(leftType, node.left); + } + } + } + + function onRight(right: Expression, state: WorkArea, _node: BinaryExpression) { + if (!state.skip) { + return maybeCheckExpression(state, right); + } + } + + function onExit(node: BinaryExpression, state: WorkArea): Type | undefined { + let result: Type | undefined; + if (state.skip) { + result = getLastResult(state); + } + else { + const leftType = getLeftType(state); + Debug.assertIsDefined(leftType); + + const rightType = getLastResult(state); + Debug.assertIsDefined(rightType); + + result = checkBinaryLikeExpressionWorker(node.left, node.operatorToken, node.right, leftType, rightType, state.checkMode, node); + } + + state.skip = false; + setLeftType(state, /*type*/ undefined); + setLastResult(state, /*type*/ undefined); + state.stackIndex--; + return result; + } + + function foldState(state: WorkArea, result: Type | undefined, _side: "left" | "right") { + setLastResult(state, result); + return state; + } + + function maybeCheckExpression(state: WorkArea, node: Expression): BinaryExpression | undefined { + if (isBinaryExpression(node)) { + return node; + } + setLastResult(state, checkExpression(node, state.checkMode)); + } + + function getLeftType(state: WorkArea) { + return state.typeStack[state.stackIndex]; + } + + function setLeftType(state: WorkArea, type: Type | undefined) { + state.typeStack[state.stackIndex] = type; + } + + function getLastResult(state: WorkArea) { + return state.typeStack[state.stackIndex + 1]; + } + + function setLastResult(state: WorkArea, type: Type | undefined) { + // To reduce overhead, reuse the next stack entry to store the + // last result. This avoids the overhead of an additional property + // on `WorkArea` and reuses empty stack entries as we walk back up + // the stack. + state.typeStack[state.stackIndex + 1] = type; + } + } + + function checkGrammarNullishCoalesceWithLogicalExpression(node: BinaryExpression) { + const { left, operatorToken, right } = node; + if (operatorToken.kind === SyntaxKind.QuestionQuestionToken) { + if (isBinaryExpression(left) && (left.operatorToken.kind === SyntaxKind.BarBarToken || left.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken)) { + grammarErrorOnNode(left, Diagnostics._0_and_1_operations_cannot_be_mixed_without_parentheses, tokenToString(left.operatorToken.kind), tokenToString(operatorToken.kind)); + } + if (isBinaryExpression(right) && (right.operatorToken.kind === SyntaxKind.BarBarToken || right.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken)) { + grammarErrorOnNode(right, Diagnostics._0_and_1_operations_cannot_be_mixed_without_parentheses, tokenToString(right.operatorToken.kind), tokenToString(operatorToken.kind)); + } + } + } + + // Note that this and `checkBinaryExpression` above should behave mostly the same, except this elides some + // expression-wide checks and does not use a work stack to fold nested binary expressions into the same callstack frame + function checkBinaryLikeExpression(left: Expression, operatorToken: BinaryOperatorToken, right: Expression, checkMode?: CheckMode, errorNode?: Node): Type { + const operator = operatorToken.kind; + if (operator === SyntaxKind.EqualsToken && (left.kind === SyntaxKind.ObjectLiteralExpression || left.kind === SyntaxKind.ArrayLiteralExpression)) { + return checkDestructuringAssignment(left, checkExpression(right, checkMode), checkMode, right.kind === SyntaxKind.ThisKeyword); + } + let leftType: Type; + if (isLogicalOrCoalescingBinaryOperator(operator)) { + leftType = checkTruthinessExpression(left, checkMode); + } + else { + leftType = checkExpression(left, checkMode); + } + + const rightType = checkExpression(right, checkMode); + return checkBinaryLikeExpressionWorker(left, operatorToken, right, leftType, rightType, checkMode, errorNode); + } + + function checkBinaryLikeExpressionWorker( + left: Expression, + operatorToken: BinaryOperatorToken, + right: Expression, + leftType: Type, + rightType: Type, + checkMode?: CheckMode, + errorNode?: Node, + ): Type { + const operator = operatorToken.kind; + switch (operator) { + case SyntaxKind.AsteriskToken: + case SyntaxKind.AsteriskAsteriskToken: + case SyntaxKind.AsteriskEqualsToken: + case SyntaxKind.AsteriskAsteriskEqualsToken: + case SyntaxKind.SlashToken: + case SyntaxKind.SlashEqualsToken: + case SyntaxKind.PercentToken: + case SyntaxKind.PercentEqualsToken: + case SyntaxKind.MinusToken: + case SyntaxKind.MinusEqualsToken: + case SyntaxKind.LessThanLessThanToken: + case SyntaxKind.LessThanLessThanEqualsToken: + case SyntaxKind.GreaterThanGreaterThanToken: + case SyntaxKind.GreaterThanGreaterThanEqualsToken: + case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: + case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken: + case SyntaxKind.BarToken: + case SyntaxKind.BarEqualsToken: + case SyntaxKind.CaretToken: + case SyntaxKind.CaretEqualsToken: + case SyntaxKind.AmpersandToken: + case SyntaxKind.AmpersandEqualsToken: + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + + leftType = checkNonNullType(leftType, left); + rightType = checkNonNullType(rightType, right); + + let suggestedOperator: PunctuationSyntaxKind | undefined; + // if a user tries to apply a bitwise operator to 2 boolean operands + // try and return them a helpful suggestion + if ( + (leftType.flags & TypeFlags.BooleanLike) && + (rightType.flags & TypeFlags.BooleanLike) && + (suggestedOperator = getSuggestedBooleanOperator(operatorToken.kind)) !== undefined + ) { + error(errorNode || operatorToken, Diagnostics.The_0_operator_is_not_allowed_for_boolean_types_Consider_using_1_instead, tokenToString(operatorToken.kind), tokenToString(suggestedOperator)); + return numberType; + } + else { + // otherwise just check each operand separately and report errors as normal + const leftOk = checkArithmeticOperandType(left, leftType, Diagnostics.The_left_hand_side_of_an_arithmetic_operation_must_be_of_type_any_number_bigint_or_an_enum_type, /*isAwaitValid*/ true); + const rightOk = checkArithmeticOperandType(right, rightType, Diagnostics.The_right_hand_side_of_an_arithmetic_operation_must_be_of_type_any_number_bigint_or_an_enum_type, /*isAwaitValid*/ true); + let resultType: Type; + // If both are any or unknown, allow operation; assume it will resolve to number + if ( + (isTypeAssignableToKind(leftType, TypeFlags.AnyOrUnknown) && isTypeAssignableToKind(rightType, TypeFlags.AnyOrUnknown)) || + // Or, if neither could be bigint, implicit coercion results in a number result + !(maybeTypeOfKind(leftType, TypeFlags.BigIntLike) || maybeTypeOfKind(rightType, TypeFlags.BigIntLike)) + ) { + resultType = numberType; + } + // At least one is assignable to bigint, so check that both are + else if (bothAreBigIntLike(leftType, rightType)) { + switch (operator) { + case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: + case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken: + reportOperatorError(); + break; + case SyntaxKind.AsteriskAsteriskToken: + case SyntaxKind.AsteriskAsteriskEqualsToken: + if (languageVersion < ScriptTarget.ES2016) { + error(errorNode, Diagnostics.Exponentiation_cannot_be_performed_on_bigint_values_unless_the_target_option_is_set_to_es2016_or_later); + } + } + resultType = bigintType; + } + // Exactly one of leftType/rightType is assignable to bigint + else { + reportOperatorError(bothAreBigIntLike); + resultType = errorType; + } + if (leftOk && rightOk) { + checkAssignmentOperator(resultType); + } + return resultType; + } + case SyntaxKind.PlusToken: + case SyntaxKind.PlusEqualsToken: + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + + if (!isTypeAssignableToKind(leftType, TypeFlags.StringLike) && !isTypeAssignableToKind(rightType, TypeFlags.StringLike)) { + leftType = checkNonNullType(leftType, left); + rightType = checkNonNullType(rightType, right); + } + + let resultType: Type | undefined; + if (isTypeAssignableToKind(leftType, TypeFlags.NumberLike, /*strict*/ true) && isTypeAssignableToKind(rightType, TypeFlags.NumberLike, /*strict*/ true)) { + // Operands of an enum type are treated as having the primitive type Number. + // If both operands are of the Number primitive type, the result is of the Number primitive type. + resultType = numberType; + } + else if (isTypeAssignableToKind(leftType, TypeFlags.BigIntLike, /*strict*/ true) && isTypeAssignableToKind(rightType, TypeFlags.BigIntLike, /*strict*/ true)) { + // If both operands are of the BigInt primitive type, the result is of the BigInt primitive type. + resultType = bigintType; + } + else if (isTypeAssignableToKind(leftType, TypeFlags.StringLike, /*strict*/ true) || isTypeAssignableToKind(rightType, TypeFlags.StringLike, /*strict*/ true)) { + // If one or both operands are of the String primitive type, the result is of the String primitive type. + resultType = stringType; + } + else if (isTypeAny(leftType) || isTypeAny(rightType)) { + // Otherwise, the result is of type Any. + // NOTE: unknown type here denotes error type. Old compiler treated this case as any type so do we. + resultType = isErrorType(leftType) || isErrorType(rightType) ? errorType : anyType; + } + + // Symbols are not allowed at all in arithmetic expressions + if (resultType && !checkForDisallowedESSymbolOperand(operator)) { + return resultType; + } + + if (!resultType) { + // Types that have a reasonably good chance of being a valid operand type. + // If both types have an awaited type of one of these, we'll assume the user + // might be missing an await without doing an exhaustive check that inserting + // await(s) will actually be a completely valid binary expression. + const closeEnoughKind = TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.AnyOrUnknown; + reportOperatorError((left, right) => + isTypeAssignableToKind(left, closeEnoughKind) && + isTypeAssignableToKind(right, closeEnoughKind) + ); + return anyType; + } + + if (operator === SyntaxKind.PlusEqualsToken) { + checkAssignmentOperator(resultType); + } + return resultType; + case SyntaxKind.LessThanToken: + case SyntaxKind.GreaterThanToken: + case SyntaxKind.LessThanEqualsToken: + case SyntaxKind.GreaterThanEqualsToken: + if (checkForDisallowedESSymbolOperand(operator)) { + leftType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(leftType, left)); + rightType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(rightType, right)); + reportOperatorErrorUnless((left, right) => { + if (isTypeAny(left) || isTypeAny(right)) { + return true; + } + const leftAssignableToNumber = isTypeAssignableTo(left, numberOrBigIntType); + const rightAssignableToNumber = isTypeAssignableTo(right, numberOrBigIntType); + return leftAssignableToNumber && rightAssignableToNumber || + !leftAssignableToNumber && !rightAssignableToNumber && areTypesComparable(left, right); + }); + } + return booleanType; + case SyntaxKind.EqualsEqualsToken: + case SyntaxKind.ExclamationEqualsToken: + case SyntaxKind.EqualsEqualsEqualsToken: + case SyntaxKind.ExclamationEqualsEqualsToken: + // We suppress errors in CheckMode.TypeOnly (meaning the invocation came from getTypeOfExpression). During + // control flow analysis it is possible for operands to temporarily have narrower types, and those narrower + // types may cause the operands to not be comparable. We don't want such errors reported (see #46475). + if (!(checkMode && checkMode & CheckMode.TypeOnly)) { + if ( + (isLiteralExpressionOfObject(left) || isLiteralExpressionOfObject(right)) && + // only report for === and !== in JS, not == or != + (!isInJSFile(left) || (operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken)) + ) { + const eqType = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken; + error(errorNode, Diagnostics.This_condition_will_always_return_0_since_JavaScript_compares_objects_by_reference_not_value, eqType ? "false" : "true"); + } + checkNaNEquality(errorNode, operator, left, right); + reportOperatorErrorUnless((left, right) => isTypeEqualityComparableTo(left, right) || isTypeEqualityComparableTo(right, left)); + } + return booleanType; + case SyntaxKind.InstanceOfKeyword: + return checkInstanceOfExpression(left, right, leftType, rightType, checkMode); + case SyntaxKind.InKeyword: + return checkInExpression(left, right, leftType, rightType); + case SyntaxKind.AmpersandAmpersandToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: { + const resultType = hasTypeFacts(leftType, TypeFacts.Truthy) ? + getUnionType([extractDefinitelyFalsyTypes(strictNullChecks ? leftType : getBaseTypeOfLiteralType(rightType)), rightType]) : + leftType; + if (operator === SyntaxKind.AmpersandAmpersandEqualsToken) { + checkAssignmentOperator(rightType); + } + return resultType; + } + case SyntaxKind.BarBarToken: + case SyntaxKind.BarBarEqualsToken: { + const resultType = hasTypeFacts(leftType, TypeFacts.Falsy) ? + getUnionType([getNonNullableType(removeDefinitelyFalsyTypes(leftType)), rightType], UnionReduction.Subtype) : + leftType; + if (operator === SyntaxKind.BarBarEqualsToken) { + checkAssignmentOperator(rightType); + } + return resultType; + } + case SyntaxKind.QuestionQuestionToken: + case SyntaxKind.QuestionQuestionEqualsToken: { + const resultType = hasTypeFacts(leftType, TypeFacts.EQUndefinedOrNull) ? + getUnionType([getNonNullableType(leftType), rightType], UnionReduction.Subtype) : + leftType; + if (operator === SyntaxKind.QuestionQuestionEqualsToken) { + checkAssignmentOperator(rightType); + } + return resultType; + } + case SyntaxKind.EqualsToken: + const declKind = isBinaryExpression(left.parent) ? getAssignmentDeclarationKind(left.parent) : AssignmentDeclarationKind.None; + checkAssignmentDeclaration(declKind, rightType); + if (isAssignmentDeclaration(declKind)) { + if ( + !(rightType.flags & TypeFlags.Object) || + declKind !== AssignmentDeclarationKind.ModuleExports && + declKind !== AssignmentDeclarationKind.Prototype && + !isEmptyObjectType(rightType) && + !isFunctionObjectType(rightType as ObjectType) && + !(getObjectFlags(rightType) & ObjectFlags.Class) + ) { + // don't check assignability of module.exports=, C.prototype=, or expando types because they will necessarily be incomplete + checkAssignmentOperator(rightType); + } + return leftType; + } + else { + checkAssignmentOperator(rightType); + return rightType; + } + case SyntaxKind.CommaToken: + if (!compilerOptions.allowUnreachableCode && isSideEffectFree(left) && !isIndirectCall(left.parent as BinaryExpression)) { + const sf = getSourceFileOfNode(left); + const sourceText = sf.text; + const start = skipTrivia(sourceText, left.pos); + const isInDiag2657 = sf.parseDiagnostics.some(diag => { + if (diag.code !== Diagnostics.JSX_expressions_must_have_one_parent_element.code) return false; + return textSpanContainsPosition(diag, start); + }); + if (!isInDiag2657) error(left, Diagnostics.Left_side_of_comma_operator_is_unused_and_has_no_side_effects); + } + return rightType; + + default: + return Debug.fail(); + } + + function bothAreBigIntLike(left: Type, right: Type): boolean { + return isTypeAssignableToKind(left, TypeFlags.BigIntLike) && isTypeAssignableToKind(right, TypeFlags.BigIntLike); + } + + function checkAssignmentDeclaration(kind: AssignmentDeclarationKind, rightType: Type) { + if (kind === AssignmentDeclarationKind.ModuleExports) { + for (const prop of getPropertiesOfObjectType(rightType)) { + const propType = getTypeOfSymbol(prop); + if (propType.symbol && propType.symbol.flags & SymbolFlags.Class) { + const name = prop.escapedName; + const symbol = resolveName(prop.valueDeclaration, name, SymbolFlags.Type, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (symbol?.declarations && symbol.declarations.some(isJSDocTypedefTag)) { + addDuplicateDeclarationErrorsForSymbols(symbol, Diagnostics.Duplicate_identifier_0, unescapeLeadingUnderscores(name), prop); + addDuplicateDeclarationErrorsForSymbols(prop, Diagnostics.Duplicate_identifier_0, unescapeLeadingUnderscores(name), symbol); + } + } + } + } + } + + // Return true for "indirect calls", (i.e. `(0, x.f)(...)` or `(0, eval)(...)`), which prevents passing `this`. + function isIndirectCall(node: BinaryExpression): boolean { + return node.parent.kind === SyntaxKind.ParenthesizedExpression && + isNumericLiteral(node.left) && + node.left.text === "0" && + (isCallExpression(node.parent.parent) && node.parent.parent.expression === node.parent || node.parent.parent.kind === SyntaxKind.TaggedTemplateExpression) && + // special-case for "eval" because it's the only non-access case where an indirect call actually affects behavior. + (isAccessExpression(node.right) || isIdentifier(node.right) && node.right.escapedText === "eval"); + } + + // Return true if there was no error, false if there was an error. + function checkForDisallowedESSymbolOperand(operator: PunctuationSyntaxKind): boolean { + const offendingSymbolOperand = maybeTypeOfKindConsideringBaseConstraint(leftType, TypeFlags.ESSymbolLike) ? left : + maybeTypeOfKindConsideringBaseConstraint(rightType, TypeFlags.ESSymbolLike) ? right : + undefined; + + if (offendingSymbolOperand) { + error(offendingSymbolOperand, Diagnostics.The_0_operator_cannot_be_applied_to_type_symbol, tokenToString(operator)); + return false; + } + + return true; + } + + function getSuggestedBooleanOperator(operator: SyntaxKind): PunctuationSyntaxKind | undefined { + switch (operator) { + case SyntaxKind.BarToken: + case SyntaxKind.BarEqualsToken: + return SyntaxKind.BarBarToken; + case SyntaxKind.CaretToken: + case SyntaxKind.CaretEqualsToken: + return SyntaxKind.ExclamationEqualsEqualsToken; + case SyntaxKind.AmpersandToken: + case SyntaxKind.AmpersandEqualsToken: + return SyntaxKind.AmpersandAmpersandToken; + default: + return undefined; + } + } + + function checkAssignmentOperator(valueType: Type): void { + if (isAssignmentOperator(operator)) { + addLazyDiagnostic(checkAssignmentOperatorWorker); + } + + function checkAssignmentOperatorWorker() { + let assigneeType = leftType; + + // getters can be a subtype of setters, so to check for assignability we use the setter's type instead + if (isCompoundAssignment(operatorToken.kind) && left.kind === SyntaxKind.PropertyAccessExpression) { + assigneeType = checkPropertyAccessExpression(left as PropertyAccessExpression, /*checkMode*/ undefined, /*writeOnly*/ true); + } + + // TypeScript 1.0 spec (April 2014): 4.17 + // An assignment of the form + // VarExpr = ValueExpr + // requires VarExpr to be classified as a reference + // A compound assignment furthermore requires VarExpr to be classified as a reference (section 4.1) + // and the type of the non-compound operation to be assignable to the type of VarExpr. + + if (checkReferenceExpression(left, Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access, Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access)) { + let headMessage: DiagnosticMessage | undefined; + if (exactOptionalPropertyTypes && isPropertyAccessExpression(left) && maybeTypeOfKind(valueType, TypeFlags.Undefined)) { + const target = getTypeOfPropertyOfType(getTypeOfExpression(left.expression), left.name.escapedText); + if (isExactOptionalPropertyMismatch(valueType, target)) { + headMessage = Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target; + } + } + // to avoid cascading errors check assignability only if 'isReference' check succeeded and no errors were reported + checkTypeAssignableToAndOptionallyElaborate(valueType, assigneeType, left, right, headMessage); + } + } + } + + function isAssignmentDeclaration(kind: AssignmentDeclarationKind) { + switch (kind) { + case AssignmentDeclarationKind.ModuleExports: + return true; + case AssignmentDeclarationKind.ExportsProperty: + case AssignmentDeclarationKind.Property: + case AssignmentDeclarationKind.Prototype: + case AssignmentDeclarationKind.PrototypeProperty: + case AssignmentDeclarationKind.ThisProperty: + const symbol = getSymbolOfNode(left); + const init = getAssignedExpandoInitializer(right); + return !!init && isObjectLiteralExpression(init) && + !!symbol?.exports?.size; + default: + return false; + } + } + + /** + * Returns true if an error is reported + */ + function reportOperatorErrorUnless(typesAreCompatible: (left: Type, right: Type) => boolean): boolean { + if (!typesAreCompatible(leftType, rightType)) { + reportOperatorError(typesAreCompatible); + return true; + } + return false; + } + + function reportOperatorError(isRelated?: (left: Type, right: Type) => boolean) { + let wouldWorkWithAwait = false; + const errNode = errorNode || operatorToken; + if (isRelated) { + const awaitedLeftType = getAwaitedTypeNoAlias(leftType); + const awaitedRightType = getAwaitedTypeNoAlias(rightType); + wouldWorkWithAwait = !(awaitedLeftType === leftType && awaitedRightType === rightType) + && !!(awaitedLeftType && awaitedRightType) + && isRelated(awaitedLeftType, awaitedRightType); + } + + let effectiveLeft = leftType; + let effectiveRight = rightType; + if (!wouldWorkWithAwait && isRelated) { + [effectiveLeft, effectiveRight] = getBaseTypesIfUnrelated(leftType, rightType, isRelated); + } + const [leftStr, rightStr] = getTypeNamesForErrorDisplay(effectiveLeft, effectiveRight); + if (!tryGiveBetterPrimaryError(errNode, wouldWorkWithAwait, leftStr, rightStr)) { + errorAndMaybeSuggestAwait( + errNode, + wouldWorkWithAwait, + Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2, + tokenToString(operatorToken.kind), + leftStr, + rightStr, + ); + } + } + + function tryGiveBetterPrimaryError(errNode: Node, maybeMissingAwait: boolean, leftStr: string, rightStr: string) { + switch (operatorToken.kind) { + case SyntaxKind.EqualsEqualsEqualsToken: + case SyntaxKind.EqualsEqualsToken: + case SyntaxKind.ExclamationEqualsEqualsToken: + case SyntaxKind.ExclamationEqualsToken: + return errorAndMaybeSuggestAwait( + errNode, + maybeMissingAwait, + Diagnostics.This_comparison_appears_to_be_unintentional_because_the_types_0_and_1_have_no_overlap, + leftStr, + rightStr, + ); + default: + return undefined; + } + } + + function checkNaNEquality(errorNode: Node | undefined, operator: SyntaxKind, left: Expression, right: Expression) { + const isLeftNaN = isGlobalNaN(skipParentheses(left)); + const isRightNaN = isGlobalNaN(skipParentheses(right)); + if (isLeftNaN || isRightNaN) { + const err = error(errorNode, Diagnostics.This_condition_will_always_return_0, tokenToString(operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.EqualsEqualsToken ? SyntaxKind.FalseKeyword : SyntaxKind.TrueKeyword)); + if (isLeftNaN && isRightNaN) return; + const operatorString = operator === SyntaxKind.ExclamationEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken ? tokenToString(SyntaxKind.ExclamationToken) : ""; + const location = isLeftNaN ? right : left; + const expression = skipParentheses(location); + addRelatedInfo(err, createDiagnosticForNode(location, Diagnostics.Did_you_mean_0, `${operatorString}Number.isNaN(${isEntityNameExpression(expression) ? entityNameToString(expression) : "..."})`)); + } + } + + function isGlobalNaN(expr: Expression): boolean { + if (isIdentifier(expr) && expr.escapedText === "NaN") { + const globalNaNSymbol = getGlobalNaNSymbol(); + return !!globalNaNSymbol && globalNaNSymbol === getResolvedSymbol(expr); + } + return false; + } + } + + function getBaseTypesIfUnrelated(leftType: Type, rightType: Type, isRelated: (left: Type, right: Type) => boolean): [Type, Type] { + let effectiveLeft = leftType; + let effectiveRight = rightType; + const leftBase = getBaseTypeOfLiteralType(leftType); + const rightBase = getBaseTypeOfLiteralType(rightType); + if (!isRelated(leftBase, rightBase)) { + effectiveLeft = leftBase; + effectiveRight = rightBase; + } + return [effectiveLeft, effectiveRight]; + } + + function checkYieldExpression(node: YieldExpression): Type { + addLazyDiagnostic(checkYieldExpressionGrammar); + + const func = getContainingFunction(node); + if (!func) return anyType; + const functionFlags = getFunctionFlags(func); + + if (!(functionFlags & FunctionFlags.Generator)) { + // If the user's code is syntactically correct, the func should always have a star. After all, we are in a yield context. + return anyType; + } + + const isAsync = (functionFlags & FunctionFlags.Async) !== 0; + if (node.asteriskToken) { + // Async generator functions prior to ES2018 require the __await, __asyncDelegator, + // and __asyncValues helpers + if (isAsync && languageVersion < LanguageFeatureMinimumTarget.AsyncGenerators) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.AsyncDelegatorIncludes); + } + + // Generator functions prior to ES2015 require the __values helper + if (!isAsync && languageVersion < LanguageFeatureMinimumTarget.Generators && compilerOptions.downlevelIteration) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Values); + } + } + + // There is no point in doing an assignability check if the function + // has no explicit return type because the return type is directly computed + // from the yield expressions. + let returnType = getReturnTypeFromAnnotation(func); + if (returnType && returnType.flags & TypeFlags.Union) { + returnType = filterType(returnType, t => checkGeneratorInstantiationAssignabilityToReturnType(t, functionFlags, /*errorNode*/ undefined)); + } + const iterationTypes = returnType && getIterationTypesOfGeneratorFunctionReturnType(returnType, isAsync); + const signatureYieldType = iterationTypes && iterationTypes.yieldType || anyType; + const signatureNextType = iterationTypes && iterationTypes.nextType || anyType; + const resolvedSignatureNextType = isAsync ? getAwaitedType(signatureNextType) || anyType : signatureNextType; + const yieldExpressionType = node.expression ? checkExpression(node.expression) : undefinedWideningType; + const yieldedType = getYieldedTypeOfYieldExpression(node, yieldExpressionType, resolvedSignatureNextType, isAsync); + if (returnType && yieldedType) { + checkTypeAssignableToAndOptionallyElaborate(yieldedType, signatureYieldType, node.expression || node, node.expression); + } + + if (node.asteriskToken) { + const use = isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar; + return getIterationTypeOfIterable(use, IterationTypeKind.Return, yieldExpressionType, node.expression) + || anyType; + } + else if (returnType) { + return getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Next, returnType, isAsync) + || anyType; + } + let type = getContextualIterationType(IterationTypeKind.Next, func); + if (!type) { + type = anyType; + addLazyDiagnostic(() => { + if (noImplicitAny && !expressionResultIsUnused(node)) { + const contextualType = getContextualType(node, /*contextFlags*/ undefined); + if (!contextualType || isTypeAny(contextualType)) { + error(node, Diagnostics.yield_expression_implicitly_results_in_an_any_type_because_its_containing_generator_lacks_a_return_type_annotation); + } + } + }); + } + return type; + + function checkYieldExpressionGrammar() { + if (!(node.flags & NodeFlags.YieldContext)) { + grammarErrorOnFirstToken(node, Diagnostics.A_yield_expression_is_only_allowed_in_a_generator_body); + } + + if (isInParameterInitializerBeforeContainingFunction(node)) { + error(node, Diagnostics.yield_expressions_cannot_be_used_in_a_parameter_initializer); + } + } + } + + function checkConditionalExpression(node: ConditionalExpression, checkMode?: CheckMode): Type { + const type = checkTruthinessExpression(node.condition, checkMode); + checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(node.condition, type, node.whenTrue); + const type1 = checkExpression(node.whenTrue, checkMode); + const type2 = checkExpression(node.whenFalse, checkMode); + return getUnionType([type1, type2], UnionReduction.Subtype); + } + + function isTemplateLiteralContext(node: Node): boolean { + const parent = node.parent; + return isParenthesizedExpression(parent) && isTemplateLiteralContext(parent) || + isElementAccessExpression(parent) && parent.argumentExpression === node; + } + + function checkTemplateExpression(node: TemplateExpression): Type { + const texts = [node.head.text]; + const types = []; + for (const span of node.templateSpans) { + const type = checkExpression(span.expression); + if (maybeTypeOfKindConsideringBaseConstraint(type, TypeFlags.ESSymbolLike)) { + error(span.expression, Diagnostics.Implicit_conversion_of_a_symbol_to_a_string_will_fail_at_runtime_Consider_wrapping_this_expression_in_String); + } + texts.push(span.literal.text); + types.push(isTypeAssignableTo(type, templateConstraintType) ? type : stringType); + } + const evaluated = node.parent.kind !== SyntaxKind.TaggedTemplateExpression && evaluate(node).value; + if (evaluated) { + return getFreshTypeOfLiteralType(getStringLiteralType(evaluated)); + } + if (isConstContext(node) || isTemplateLiteralContext(node) || someType(getContextualType(node, /*contextFlags*/ undefined) || unknownType, isTemplateLiteralContextualType)) { + return getTemplateLiteralType(texts, types); + } + return stringType; + } + + function isTemplateLiteralContextualType(type: Type): boolean { + return !!(type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral) || + type.flags & TypeFlags.InstantiableNonPrimitive && maybeTypeOfKind(getBaseConstraintOfType(type) || unknownType, TypeFlags.StringLike)); + } + + function getContextNode(node: Expression): Expression { + if (isJsxAttributes(node) && !isJsxSelfClosingElement(node.parent)) { + return node.parent.parent; // Needs to be the root JsxElement, so it encompasses the attributes _and_ the children (which are essentially part of the attributes) + } + return node; + } + + function checkExpressionWithContextualType(node: Expression, contextualType: Type, inferenceContext: InferenceContext | undefined, checkMode: CheckMode): Type { + const contextNode = getContextNode(node); + pushContextualType(contextNode, contextualType, /*isCache*/ false); + pushInferenceContext(contextNode, inferenceContext); + const type = checkExpression(node, checkMode | CheckMode.Contextual | (inferenceContext ? CheckMode.Inferential : 0)); + // In CheckMode.Inferential we collect intra-expression inference sites to process before fixing any type + // parameters. This information is no longer needed after the call to checkExpression. + if (inferenceContext && inferenceContext.intraExpressionInferenceSites) { + inferenceContext.intraExpressionInferenceSites = undefined; + } + // We strip literal freshness when an appropriate contextual type is present such that contextually typed + // literals always preserve their literal types (otherwise they might widen during type inference). An alternative + // here would be to not mark contextually typed literals as fresh in the first place. + const result = maybeTypeOfKind(type, TypeFlags.Literal) && isLiteralOfContextualType(type, instantiateContextualType(contextualType, node, /*contextFlags*/ undefined)) ? + getRegularTypeOfLiteralType(type) : type; + popInferenceContext(); + popContextualType(); + return result; + } + + function checkExpressionCached(node: Expression | QualifiedName, checkMode?: CheckMode): Type { + if (checkMode) { + return checkExpression(node, checkMode); + } + const links = getNodeLinks(node); + if (!links.resolvedType) { + // When computing a type that we're going to cache, we need to ignore any ongoing control flow + // analysis because variables may have transient types in indeterminable states. Moving flowLoopStart + // to the top of the stack ensures all transient types are computed from a known point. + const saveFlowLoopStart = flowLoopStart; + const saveFlowTypeCache = flowTypeCache; + flowLoopStart = flowLoopCount; + flowTypeCache = undefined; + links.resolvedType = checkExpression(node, checkMode); + flowTypeCache = saveFlowTypeCache; + flowLoopStart = saveFlowLoopStart; + } + return links.resolvedType; + } + + function isTypeAssertion(node: Expression) { + node = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + return node.kind === SyntaxKind.TypeAssertionExpression || + node.kind === SyntaxKind.AsExpression || + isJSDocTypeAssertion(node); + } + + function checkDeclarationInitializer( + declaration: HasExpressionInitializer, + checkMode: CheckMode, + contextualType?: Type | undefined, + ) { + const initializer = getEffectiveInitializer(declaration)!; + if (isInJSFile(declaration)) { + const typeNode = tryGetJSDocSatisfiesTypeNode(declaration); + if (typeNode) { + return checkSatisfiesExpressionWorker(initializer, typeNode, checkMode); + } + } + const type = getQuickTypeOfExpression(initializer) || + (contextualType ? + checkExpressionWithContextualType(initializer, contextualType, /*inferenceContext*/ undefined, checkMode || CheckMode.Normal) + : checkExpressionCached(initializer, checkMode)); + return isParameter(declaration) && declaration.name.kind === SyntaxKind.ArrayBindingPattern && + isTupleType(type) && !(type.target.combinedFlags & ElementFlags.Variable) && getTypeReferenceArity(type) < declaration.name.elements.length ? + padTupleType(type, declaration.name) : type; + } + + function padTupleType(type: TupleTypeReference, pattern: ArrayBindingPattern) { + const patternElements = pattern.elements; + const elementTypes = getElementTypes(type).slice(); + const elementFlags = type.target.elementFlags.slice(); + for (let i = getTypeReferenceArity(type); i < patternElements.length; i++) { + const e = patternElements[i]; + if (i < patternElements.length - 1 || !(e.kind === SyntaxKind.BindingElement && e.dotDotDotToken)) { + elementTypes.push(!isOmittedExpression(e) && hasDefaultValue(e) ? getTypeFromBindingElement(e, /*includePatternInType*/ false, /*reportErrors*/ false) : anyType); + elementFlags.push(ElementFlags.Optional); + if (!isOmittedExpression(e) && !hasDefaultValue(e)) { + reportImplicitAny(e, anyType); + } + } + } + return createTupleType(elementTypes, elementFlags, type.target.readonly); + } + + function widenTypeInferredFromInitializer(declaration: HasExpressionInitializer, type: Type) { + const widened = getCombinedNodeFlagsCached(declaration) & NodeFlags.Constant || isDeclarationReadonly(declaration) ? type : getWidenedLiteralType(type); + if (isInJSFile(declaration)) { + if (isEmptyLiteralType(widened)) { + reportImplicitAny(declaration, anyType); + return anyType; + } + else if (isEmptyArrayLiteralType(widened)) { + reportImplicitAny(declaration, anyArrayType); + return anyArrayType; + } + } + return widened; + } + + function isLiteralOfContextualType(candidateType: Type, contextualType: Type | undefined): boolean { + if (contextualType) { + if (contextualType.flags & TypeFlags.UnionOrIntersection) { + const types = (contextualType as UnionType).types; + return some(types, t => isLiteralOfContextualType(candidateType, t)); + } + if (contextualType.flags & TypeFlags.InstantiableNonPrimitive) { + // If the contextual type is a type variable constrained to a primitive type, consider + // this a literal context for literals of that primitive type. For example, given a + // type parameter 'T extends string', infer string literal types for T. + const constraint = getBaseConstraintOfType(contextualType) || unknownType; + return maybeTypeOfKind(constraint, TypeFlags.String) && maybeTypeOfKind(candidateType, TypeFlags.StringLiteral) || + maybeTypeOfKind(constraint, TypeFlags.Number) && maybeTypeOfKind(candidateType, TypeFlags.NumberLiteral) || + maybeTypeOfKind(constraint, TypeFlags.BigInt) && maybeTypeOfKind(candidateType, TypeFlags.BigIntLiteral) || + maybeTypeOfKind(constraint, TypeFlags.ESSymbol) && maybeTypeOfKind(candidateType, TypeFlags.UniqueESSymbol) || + isLiteralOfContextualType(candidateType, constraint); + } + // If the contextual type is a literal of a particular primitive type, we consider this a + // literal context for all literals of that primitive type. + return !!(contextualType.flags & (TypeFlags.StringLiteral | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && maybeTypeOfKind(candidateType, TypeFlags.StringLiteral) || + contextualType.flags & TypeFlags.NumberLiteral && maybeTypeOfKind(candidateType, TypeFlags.NumberLiteral) || + contextualType.flags & TypeFlags.BigIntLiteral && maybeTypeOfKind(candidateType, TypeFlags.BigIntLiteral) || + contextualType.flags & TypeFlags.BooleanLiteral && maybeTypeOfKind(candidateType, TypeFlags.BooleanLiteral) || + contextualType.flags & TypeFlags.UniqueESSymbol && maybeTypeOfKind(candidateType, TypeFlags.UniqueESSymbol)); + } + return false; + } + + function isConstContext(node: Expression): boolean { + const parent = node.parent; + return isAssertionExpression(parent) && isConstTypeReference(parent.type) || + isJSDocTypeAssertion(parent) && isConstTypeReference(getJSDocTypeAssertionType(parent)) || + isValidConstAssertionArgument(node) && isConstTypeVariable(getContextualType(node, ContextFlags.None)) || + (isParenthesizedExpression(parent) || isArrayLiteralExpression(parent) || isSpreadElement(parent)) && isConstContext(parent) || + (isPropertyAssignment(parent) || isShorthandPropertyAssignment(parent) || isTemplateSpan(parent)) && isConstContext(parent.parent); + } + + function checkExpressionForMutableLocation(node: Expression, checkMode: CheckMode | undefined, forceTuple?: boolean): Type { + const type = checkExpression(node, checkMode, forceTuple); + return isConstContext(node) || isCommonJsExportedExpression(node) ? getRegularTypeOfLiteralType(type) : + isTypeAssertion(node) ? type : + getWidenedLiteralLikeTypeForContextualType(type, instantiateContextualType(getContextualType(node, /*contextFlags*/ undefined), node, /*contextFlags*/ undefined)); + } + + function checkPropertyAssignment(node: PropertyAssignment, checkMode?: CheckMode): Type { + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + } + + return checkExpressionForMutableLocation(node.initializer, checkMode); + } + + function checkObjectLiteralMethod(node: MethodDeclaration, checkMode?: CheckMode): Type { + // Grammar checking + checkGrammarMethod(node); + + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + } + + const uninstantiatedType = checkFunctionExpressionOrObjectLiteralMethod(node, checkMode); + return instantiateTypeWithSingleGenericCallSignature(node, uninstantiatedType, checkMode); + } + + function instantiateTypeWithSingleGenericCallSignature(node: Expression | MethodDeclaration | QualifiedName, type: Type, checkMode?: CheckMode) { + if (checkMode && checkMode & (CheckMode.Inferential | CheckMode.SkipGenericFunctions)) { + const callSignature = getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ true); + const constructSignature = getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ true); + const signature = callSignature || constructSignature; + if (signature && signature.typeParameters) { + const contextualType = getApparentTypeOfContextualType(node as Expression, ContextFlags.NoConstraints); + if (contextualType) { + const contextualSignature = getSingleSignature(getNonNullableType(contextualType), callSignature ? SignatureKind.Call : SignatureKind.Construct, /*allowMembers*/ false); + if (contextualSignature && !contextualSignature.typeParameters) { + if (checkMode & CheckMode.SkipGenericFunctions) { + skippedGenericFunction(node, checkMode); + return anyFunctionType; + } + const context = getInferenceContext(node)!; + // We have an expression that is an argument of a generic function for which we are performing + // type argument inference. The expression is of a function type with a single generic call + // signature and a contextual function type with a single non-generic call signature. Now check + // if the outer function returns a function type with a single non-generic call signature and + // if some of the outer function type parameters have no inferences so far. If so, we can + // potentially add inferred type parameters to the outer function return type. + const returnType = context.signature && getReturnTypeOfSignature(context.signature); + const returnSignature = returnType && getSingleCallOrConstructSignature(returnType); + if (returnSignature && !returnSignature.typeParameters && !every(context.inferences, hasInferenceCandidates)) { + // Instantiate the signature with its own type parameters as type arguments, possibly + // renaming the type parameters to ensure they have unique names. + const uniqueTypeParameters = getUniqueTypeParameters(context, signature.typeParameters); + const instantiatedSignature = getSignatureInstantiationWithoutFillingInTypeArguments(signature, uniqueTypeParameters); + // Infer from the parameters of the instantiated signature to the parameters of the + // contextual signature starting with an empty set of inference candidates. + const inferences = map(context.inferences, info => createInferenceInfo(info.typeParameter)); + applyToParameterTypes(instantiatedSignature, contextualSignature, (source, target) => { + inferTypes(inferences, source, target, /*priority*/ 0, /*contravariant*/ true); + }); + if (some(inferences, hasInferenceCandidates)) { + // We have inference candidates, indicating that one or more type parameters are referenced + // in the parameter types of the contextual signature. Now also infer from the return type. + applyToReturnTypes(instantiatedSignature, contextualSignature, (source, target) => { + inferTypes(inferences, source, target); + }); + // If the type parameters for which we produced candidates do not have any inferences yet, + // we adopt the new inference candidates and add the type parameters of the expression type + // to the set of inferred type parameters for the outer function return type. + if (!hasOverlappingInferences(context.inferences, inferences)) { + mergeInferences(context.inferences, inferences); + context.inferredTypeParameters = concatenate(context.inferredTypeParameters, uniqueTypeParameters); + return getOrCreateTypeFromSignature(instantiatedSignature); + } + } + } + // TODO: The signature may reference any outer inference contexts, but we map pop off and then apply new inference contexts, and thus get different inferred types. + // That this is cached on the *first* such attempt is not currently an issue, since expression types *also* get cached on the first pass. If we ever properly speculate, though, + // the cached "isolatedSignatureType" signature field absolutely needs to be included in the list of speculative caches. + return getOrCreateTypeFromSignature(instantiateSignatureInContextOf(signature, contextualSignature, context), flatMap(inferenceContexts, c => c && map(c.inferences, i => i.typeParameter)).slice()); + } + } + } + } + return type; + } + + function skippedGenericFunction(node: Node, checkMode: CheckMode) { + if (checkMode & CheckMode.Inferential) { + // We have skipped a generic function during inferential typing. Obtain the inference context and + // indicate this has occurred such that we know a second pass of inference is be needed. + const context = getInferenceContext(node)!; + context.flags |= InferenceFlags.SkippedGenericFunction; + } + } + + function hasInferenceCandidates(info: InferenceInfo) { + return !!(info.candidates || info.contraCandidates); + } + + function hasInferenceCandidatesOrDefault(info: InferenceInfo) { + return !!(info.candidates || info.contraCandidates || hasTypeParameterDefault(info.typeParameter)); + } + + function hasOverlappingInferences(a: InferenceInfo[], b: InferenceInfo[]) { + for (let i = 0; i < a.length; i++) { + if (hasInferenceCandidates(a[i]) && hasInferenceCandidates(b[i])) { + return true; + } + } + return false; + } + + function mergeInferences(target: InferenceInfo[], source: InferenceInfo[]) { + for (let i = 0; i < target.length; i++) { + if (!hasInferenceCandidates(target[i]) && hasInferenceCandidates(source[i])) { + target[i] = source[i]; + } + } + } + + function getUniqueTypeParameters(context: InferenceContext, typeParameters: readonly TypeParameter[]): readonly TypeParameter[] { + const result: TypeParameter[] = []; + let oldTypeParameters: TypeParameter[] | undefined; + let newTypeParameters: TypeParameter[] | undefined; + for (const tp of typeParameters) { + const name = tp.symbol.escapedName; + if (hasTypeParameterByName(context.inferredTypeParameters, name) || hasTypeParameterByName(result, name)) { + const newName = getUniqueTypeParameterName(concatenate(context.inferredTypeParameters, result), name); + const symbol = createSymbol(SymbolFlags.TypeParameter, newName); + const newTypeParameter = createTypeParameter(symbol); + newTypeParameter.target = tp; + oldTypeParameters = append(oldTypeParameters, tp); + newTypeParameters = append(newTypeParameters, newTypeParameter); + result.push(newTypeParameter); + } + else { + result.push(tp); + } + } + if (newTypeParameters) { + const mapper = createTypeMapper(oldTypeParameters!, newTypeParameters); + for (const tp of newTypeParameters) { + tp.mapper = mapper; + } + } + return result; + } + + function hasTypeParameterByName(typeParameters: readonly TypeParameter[] | undefined, name: __String) { + return some(typeParameters, tp => tp.symbol.escapedName === name); + } + + function getUniqueTypeParameterName(typeParameters: readonly TypeParameter[], baseName: __String) { + let len = (baseName as string).length; + while (len > 1 && (baseName as string).charCodeAt(len - 1) >= CharacterCodes._0 && (baseName as string).charCodeAt(len - 1) <= CharacterCodes._9) len--; + const s = (baseName as string).slice(0, len); + for (let index = 1; true; index++) { + const augmentedName = s + index as __String; + if (!hasTypeParameterByName(typeParameters, augmentedName)) { + return augmentedName; + } + } + } + + function getReturnTypeOfSingleNonGenericCallSignature(funcType: Type) { + const signature = getSingleCallSignature(funcType); + if (signature && !signature.typeParameters) { + return getReturnTypeOfSignature(signature); + } + } + + function getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr: CallChain) { + const funcType = checkExpression(expr.expression); + const nonOptionalType = getOptionalExpressionType(funcType, expr.expression); + const returnType = getReturnTypeOfSingleNonGenericCallSignature(funcType); + return returnType && propagateOptionalTypeMarker(returnType, expr, nonOptionalType !== funcType); + } + + /** + * Returns the type of an expression. Unlike checkExpression, this function is simply concerned + * with computing the type and may not fully check all contained sub-expressions for errors. + */ + function getTypeOfExpression(node: Expression) { + // Don't bother caching types that require no flow analysis and are quick to compute. + const quickType = getQuickTypeOfExpression(node); + if (quickType) { + return quickType; + } + // If a type has been cached for the node, return it. + if (node.flags & NodeFlags.TypeCached && flowTypeCache) { + const cachedType = flowTypeCache[getNodeId(node)]; + if (cachedType) { + return cachedType; + } + } + const startInvocationCount = flowInvocationCount; + const type = checkExpression(node, CheckMode.TypeOnly); + // If control flow analysis was required to determine the type, it is worth caching. + if (flowInvocationCount !== startInvocationCount) { + const cache = flowTypeCache || (flowTypeCache = []); + cache[getNodeId(node)] = type; + setNodeFlags(node, node.flags | NodeFlags.TypeCached); + } + return type; + } + + function getQuickTypeOfExpression(node: Expression): Type | undefined { + let expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + if (isJSDocTypeAssertion(expr)) { + const type = getJSDocTypeAssertionType(expr); + if (!isConstTypeReference(type)) { + return getTypeFromTypeNode(type); + } + } + expr = skipParentheses(node); + if (isAwaitExpression(expr)) { + const type = getQuickTypeOfExpression(expr.expression); + return type ? getAwaitedType(type) : undefined; + } + // Optimize for the common case of a call to a function with a single non-generic call + // signature where we can just fetch the return type without checking the arguments. + if (isCallExpression(expr) && expr.expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(expr, /*requireStringLiteralLikeArgument*/ true) && !isSymbolOrSymbolForCall(expr)) { + return isCallChain(expr) ? getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr) : + getReturnTypeOfSingleNonGenericCallSignature(checkNonNullExpression(expr.expression)); + } + else if (isAssertionExpression(expr) && !isConstTypeReference(expr.type)) { + return getTypeFromTypeNode((expr as TypeAssertion).type); + } + else if (isLiteralExpression(node) || isBooleanLiteral(node)) { + return checkExpression(node); + } + return undefined; + } + + /** + * Returns the type of an expression. Unlike checkExpression, this function is simply concerned + * with computing the type and may not fully check all contained sub-expressions for errors. + * It is intended for uses where you know there is no contextual type, + * and requesting the contextual type might cause a circularity or other bad behaviour. + * It sets the contextual type of the node to any before calling getTypeOfExpression. + */ + function getContextFreeTypeOfExpression(node: Expression) { + const links = getNodeLinks(node); + if (links.contextFreeType) { + return links.contextFreeType; + } + pushContextualType(node, anyType, /*isCache*/ false); + const type = links.contextFreeType = checkExpression(node, CheckMode.SkipContextSensitive); + popContextualType(); + return type; + } + + function checkExpression(node: Expression | QualifiedName, checkMode?: CheckMode, forceTuple?: boolean): Type { + tracing?.push(tracing.Phase.Check, "checkExpression", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); + const saveCurrentNode = currentNode; + currentNode = node; + instantiationCount = 0; + const uninstantiatedType = checkExpressionWorker(node, checkMode, forceTuple); + const type = instantiateTypeWithSingleGenericCallSignature(node, uninstantiatedType, checkMode); + if (isConstEnumObjectType(type)) { + checkConstEnumAccess(node, type); + } + currentNode = saveCurrentNode; + tracing?.pop(); + return type; + } + + function checkConstEnumAccess(node: Expression | QualifiedName, type: Type) { + // enum object type for const enums are only permitted in: + // - 'left' in property access + // - 'object' in indexed access + // - target in rhs of import statement + const ok = (node.parent.kind === SyntaxKind.PropertyAccessExpression && (node.parent as PropertyAccessExpression).expression === node) || + (node.parent.kind === SyntaxKind.ElementAccessExpression && (node.parent as ElementAccessExpression).expression === node) || + ((node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.QualifiedName) && isInRightSideOfImportOrExportAssignment(node as Identifier) || + (node.parent.kind === SyntaxKind.TypeQuery && (node.parent as TypeQueryNode).exprName === node)) || + (node.parent.kind === SyntaxKind.ExportSpecifier); // We allow reexporting const enums + + if (!ok) { + error(node, Diagnostics.const_enums_can_only_be_used_in_property_or_index_access_expressions_or_the_right_hand_side_of_an_import_declaration_or_export_assignment_or_type_query); + } + + if (getIsolatedModules(compilerOptions)) { + Debug.assert(!!(type.symbol.flags & SymbolFlags.ConstEnum)); + const constEnumDeclaration = type.symbol.valueDeclaration as EnumDeclaration; + const redirect = host.getRedirectReferenceForResolutionFromSourceOfProject(getSourceFileOfNode(constEnumDeclaration).resolvedPath); + if (constEnumDeclaration.flags & NodeFlags.Ambient && !isValidTypeOnlyAliasUseSite(node) && (!redirect || !shouldPreserveConstEnums(redirect.commandLine.options))) { + error(node, Diagnostics.Cannot_access_ambient_const_enums_when_0_is_enabled, isolatedModulesLikeFlagName); + } + } + } + + function checkParenthesizedExpression(node: ParenthesizedExpression, checkMode?: CheckMode): Type { + if (hasJSDocNodes(node)) { + if (isJSDocSatisfiesExpression(node)) { + return checkSatisfiesExpressionWorker(node.expression, getJSDocSatisfiesExpressionType(node), checkMode); + } + if (isJSDocTypeAssertion(node)) { + return checkAssertionWorker(node, checkMode); + } + } + return checkExpression(node.expression, checkMode); + } + + function checkExpressionWorker(node: Expression | QualifiedName, checkMode: CheckMode | undefined, forceTuple?: boolean): Type { + const kind = node.kind; + if (cancellationToken) { + // Only bother checking on a few construct kinds. We don't want to be excessively + // hitting the cancellation token on every node we check. + switch (kind) { + case SyntaxKind.ClassExpression: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + cancellationToken.throwIfCancellationRequested(); + } + } + switch (kind) { + case SyntaxKind.Identifier: + return checkIdentifier(node as Identifier, checkMode); + case SyntaxKind.PrivateIdentifier: + return checkPrivateIdentifierExpression(node as PrivateIdentifier); + case SyntaxKind.ThisKeyword: + return checkThisExpression(node); + case SyntaxKind.SuperKeyword: + return checkSuperExpression(node); + case SyntaxKind.NullKeyword: + return nullWideningType; + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.StringLiteral: + return hasSkipDirectInferenceFlag(node) ? + blockedStringType : + getFreshTypeOfLiteralType(getStringLiteralType((node as StringLiteralLike).text)); + case SyntaxKind.NumericLiteral: + checkGrammarNumericLiteral(node as NumericLiteral); + return getFreshTypeOfLiteralType(getNumberLiteralType(+(node as NumericLiteral).text)); + case SyntaxKind.BigIntLiteral: + checkGrammarBigIntLiteral(node as BigIntLiteral); + return getFreshTypeOfLiteralType(getBigIntLiteralType({ + negative: false, + base10Value: parsePseudoBigInt((node as BigIntLiteral).text), + })); + case SyntaxKind.TrueKeyword: + return trueType; + case SyntaxKind.FalseKeyword: + return falseType; + case SyntaxKind.TemplateExpression: + return checkTemplateExpression(node as TemplateExpression); + case SyntaxKind.RegularExpressionLiteral: + return checkRegularExpressionLiteral(node as RegularExpressionLiteral); + case SyntaxKind.ArrayLiteralExpression: + return checkArrayLiteral(node as ArrayLiteralExpression, checkMode, forceTuple); + case SyntaxKind.ObjectLiteralExpression: + return checkObjectLiteral(node as ObjectLiteralExpression, checkMode); + case SyntaxKind.PropertyAccessExpression: + return checkPropertyAccessExpression(node as PropertyAccessExpression, checkMode); + case SyntaxKind.QualifiedName: + return checkQualifiedName(node as QualifiedName, checkMode); + case SyntaxKind.ElementAccessExpression: + return checkIndexedAccess(node as ElementAccessExpression, checkMode); + case SyntaxKind.CallExpression: + if ((node as CallExpression).expression.kind === SyntaxKind.ImportKeyword) { + return checkImportCallExpression(node as ImportCall); + } + // falls through + case SyntaxKind.NewExpression: + return checkCallExpression(node as CallExpression, checkMode); + case SyntaxKind.TaggedTemplateExpression: + return checkTaggedTemplateExpression(node as TaggedTemplateExpression); + case SyntaxKind.ParenthesizedExpression: + return checkParenthesizedExpression(node as ParenthesizedExpression, checkMode); + case SyntaxKind.ClassExpression: + return checkClassExpression(node as ClassExpression); + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + return checkFunctionExpressionOrObjectLiteralMethod(node as FunctionExpression | ArrowFunction, checkMode); + case SyntaxKind.TypeOfExpression: + return checkTypeOfExpression(node as TypeOfExpression); + case SyntaxKind.TypeAssertionExpression: + case SyntaxKind.AsExpression: + return checkAssertion(node as AssertionExpression, checkMode); + case SyntaxKind.NonNullExpression: + return checkNonNullAssertion(node as NonNullExpression); + case SyntaxKind.ExpressionWithTypeArguments: + return checkExpressionWithTypeArguments(node as ExpressionWithTypeArguments); + case SyntaxKind.SatisfiesExpression: + return checkSatisfiesExpression(node as SatisfiesExpression); + case SyntaxKind.MetaProperty: + return checkMetaProperty(node as MetaProperty); + case SyntaxKind.DeleteExpression: + return checkDeleteExpression(node as DeleteExpression); + case SyntaxKind.VoidExpression: + return checkVoidExpression(node as VoidExpression); + case SyntaxKind.AwaitExpression: + return checkAwaitExpression(node as AwaitExpression); + case SyntaxKind.PrefixUnaryExpression: + return checkPrefixUnaryExpression(node as PrefixUnaryExpression); + case SyntaxKind.PostfixUnaryExpression: + return checkPostfixUnaryExpression(node as PostfixUnaryExpression); + case SyntaxKind.BinaryExpression: + return checkBinaryExpression(node as BinaryExpression, checkMode); + case SyntaxKind.ConditionalExpression: + return checkConditionalExpression(node as ConditionalExpression, checkMode); + case SyntaxKind.SpreadElement: + return checkSpreadExpression(node as SpreadElement, checkMode); + case SyntaxKind.OmittedExpression: + return undefinedWideningType; + case SyntaxKind.YieldExpression: + return checkYieldExpression(node as YieldExpression); + case SyntaxKind.SyntheticExpression: + return checkSyntheticExpression(node as SyntheticExpression); + case SyntaxKind.JsxExpression: + return checkJsxExpression(node as JsxExpression, checkMode); + case SyntaxKind.JsxElement: + return checkJsxElement(node as JsxElement, checkMode); + case SyntaxKind.JsxSelfClosingElement: + return checkJsxSelfClosingElement(node as JsxSelfClosingElement, checkMode); + case SyntaxKind.JsxFragment: + return checkJsxFragment(node as JsxFragment); + case SyntaxKind.JsxAttributes: + return checkJsxAttributes(node as JsxAttributes, checkMode); + case SyntaxKind.JsxOpeningElement: + Debug.fail("Shouldn't ever directly check a JsxOpeningElement"); + } + return errorType; + } + + // DECLARATION AND STATEMENT TYPE CHECKING + + function checkTypeParameter(node: TypeParameterDeclaration) { + // Grammar Checking + checkGrammarModifiers(node); + if (node.expression) { + grammarErrorOnFirstToken(node.expression, Diagnostics.Type_expected); + } + + checkSourceElement(node.constraint); + checkSourceElement(node.default); + const typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node)); + // Resolve base constraint to reveal circularity errors + getBaseConstraintOfType(typeParameter); + if (!hasNonCircularTypeParameterDefault(typeParameter)) { + error(node.default, Diagnostics.Type_parameter_0_has_a_circular_default, typeToString(typeParameter)); + } + const constraintType = getConstraintOfTypeParameter(typeParameter); + const defaultType = getDefaultFromTypeParameter(typeParameter); + if (constraintType && defaultType) { + checkTypeAssignableTo(defaultType, getTypeWithThisArgument(instantiateType(constraintType, makeUnaryTypeMapper(typeParameter, defaultType)), defaultType), node.default, Diagnostics.Type_0_does_not_satisfy_the_constraint_1); + } + checkNodeDeferred(node); + addLazyDiagnostic(() => checkTypeNameIsReserved(node.name, Diagnostics.Type_parameter_name_cannot_be_0)); + } + + function checkTypeParameterDeferred(node: TypeParameterDeclaration) { + if (isInterfaceDeclaration(node.parent) || isClassLike(node.parent) || isTypeAliasDeclaration(node.parent)) { + const typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node)); + const modifiers = getTypeParameterModifiers(typeParameter) & (ModifierFlags.In | ModifierFlags.Out); + if (modifiers) { + const symbol = getSymbolOfDeclaration(node.parent); + if (isTypeAliasDeclaration(node.parent) && !(getObjectFlags(getDeclaredTypeOfSymbol(symbol)) & (ObjectFlags.Reference | ObjectFlags.Anonymous | ObjectFlags.Mapped))) { + error(node, Diagnostics.Variance_annotations_are_only_supported_in_type_aliases_for_object_function_constructor_and_mapped_types); + } + else if (modifiers === ModifierFlags.In || modifiers === ModifierFlags.Out) { + tracing?.push(tracing.Phase.CheckTypes, "checkTypeParameterDeferred", { parent: getTypeId(getDeclaredTypeOfSymbol(symbol)), id: getTypeId(typeParameter) }); + const source = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSubTypeForCheck : markerSuperTypeForCheck); + const target = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSuperTypeForCheck : markerSubTypeForCheck); + const saveVarianceTypeParameter = typeParameter; + varianceTypeParameter = typeParameter; + checkTypeAssignableTo(source, target, node, Diagnostics.Type_0_is_not_assignable_to_type_1_as_implied_by_variance_annotation); + varianceTypeParameter = saveVarianceTypeParameter; + tracing?.pop(); + } + } + } + } + + function checkParameter(node: ParameterDeclaration) { + // Grammar checking + // It is a SyntaxError if the Identifier "eval" or the Identifier "arguments" occurs as the + // Identifier in a PropertySetParameterList of a PropertyAssignment that is contained in strict code + // or if its FunctionBody is strict code(11.1.5). + checkGrammarModifiers(node); + + checkVariableLikeDeclaration(node); + const func = getContainingFunction(node)!; + if (hasSyntacticModifier(node, ModifierFlags.ParameterPropertyModifier)) { + if (!(func.kind === SyntaxKind.Constructor && nodeIsPresent(func.body))) { + error(node, Diagnostics.A_parameter_property_is_only_allowed_in_a_constructor_implementation); + } + if (func.kind === SyntaxKind.Constructor && isIdentifier(node.name) && node.name.escapedText === "constructor") { + error(node.name, Diagnostics.constructor_cannot_be_used_as_a_parameter_property_name); + } + } + if (!node.initializer && isOptionalDeclaration(node) && isBindingPattern(node.name) && (func as FunctionLikeDeclaration).body) { + error(node, Diagnostics.A_binding_pattern_parameter_cannot_be_optional_in_an_implementation_signature); + } + if (node.name && isIdentifier(node.name) && (node.name.escapedText === "this" || node.name.escapedText === "new")) { + if (func.parameters.indexOf(node) !== 0) { + error(node, Diagnostics.A_0_parameter_must_be_the_first_parameter, node.name.escapedText as string); + } + if (func.kind === SyntaxKind.Constructor || func.kind === SyntaxKind.ConstructSignature || func.kind === SyntaxKind.ConstructorType) { + error(node, Diagnostics.A_constructor_cannot_have_a_this_parameter); + } + if (func.kind === SyntaxKind.ArrowFunction) { + error(node, Diagnostics.An_arrow_function_cannot_have_a_this_parameter); + } + if (func.kind === SyntaxKind.GetAccessor || func.kind === SyntaxKind.SetAccessor) { + error(node, Diagnostics.get_and_set_accessors_cannot_declare_this_parameters); + } + } + + // Only check rest parameter type if it's not a binding pattern. Since binding patterns are + // not allowed in a rest parameter, we already have an error from checkGrammarParameterList. + if (node.dotDotDotToken && !isBindingPattern(node.name) && !isTypeAssignableTo(getReducedType(getTypeOfSymbol(node.symbol)), anyReadonlyArrayType)) { + error(node, Diagnostics.A_rest_parameter_must_be_of_an_array_type); + } + } + + function checkTypePredicate(node: TypePredicateNode): void { + const parent = getTypePredicateParent(node); + if (!parent) { + // The parent must not be valid. + error(node, Diagnostics.A_type_predicate_is_only_allowed_in_return_type_position_for_functions_and_methods); + return; + } + + const signature = getSignatureFromDeclaration(parent); + const typePredicate = getTypePredicateOfSignature(signature); + if (!typePredicate) { + return; + } + + checkSourceElement(node.type); + + const { parameterName } = node; + if (typePredicate.kind === TypePredicateKind.This || typePredicate.kind === TypePredicateKind.AssertsThis) { + getTypeFromThisTypeNode(parameterName as ThisTypeNode); + } + else { + if (typePredicate.parameterIndex >= 0) { + if (signatureHasRestParameter(signature) && typePredicate.parameterIndex === signature.parameters.length - 1) { + error(parameterName, Diagnostics.A_type_predicate_cannot_reference_a_rest_parameter); + } + else { + if (typePredicate.type) { + const leadingError = () => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.A_type_predicate_s_type_must_be_assignable_to_its_parameter_s_type); + checkTypeAssignableTo(typePredicate.type, getTypeOfSymbol(signature.parameters[typePredicate.parameterIndex]), node.type, /*headMessage*/ undefined, leadingError); + } + } + } + else if (parameterName) { + let hasReportedError = false; + for (const { name } of parent.parameters) { + if ( + isBindingPattern(name) && + checkIfTypePredicateVariableIsDeclaredInBindingPattern(name, parameterName, typePredicate.parameterName) + ) { + hasReportedError = true; + break; + } + } + if (!hasReportedError) { + error(node.parameterName, Diagnostics.Cannot_find_parameter_0, typePredicate.parameterName); + } + } + } + } + + function getTypePredicateParent(node: Node): SignatureDeclaration | undefined { + switch (node.parent.kind) { + case SyntaxKind.ArrowFunction: + case SyntaxKind.CallSignature: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.FunctionType: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + const parent = node.parent as SignatureDeclaration; + if (node === parent.type) { + return parent; + } + } + } + + function checkIfTypePredicateVariableIsDeclaredInBindingPattern( + pattern: BindingPattern, + predicateVariableNode: Node, + predicateVariableName: string, + ) { + for (const element of pattern.elements) { + if (isOmittedExpression(element)) { + continue; + } + + const name = element.name; + if (name.kind === SyntaxKind.Identifier && name.escapedText === predicateVariableName) { + error(predicateVariableNode, Diagnostics.A_type_predicate_cannot_reference_element_0_in_a_binding_pattern, predicateVariableName); + return true; + } + else if (name.kind === SyntaxKind.ArrayBindingPattern || name.kind === SyntaxKind.ObjectBindingPattern) { + if ( + checkIfTypePredicateVariableIsDeclaredInBindingPattern( + name, + predicateVariableNode, + predicateVariableName, + ) + ) { + return true; + } + } + } + } + + function checkSignatureDeclaration(node: SignatureDeclaration) { + // Grammar checking + if (node.kind === SyntaxKind.IndexSignature) { + checkGrammarIndexSignature(node); + } + // TODO (yuisu): Remove this check in else-if when SyntaxKind.Construct is moved and ambient context is handled + else if ( + node.kind === SyntaxKind.FunctionType || node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.ConstructorType || + node.kind === SyntaxKind.CallSignature || node.kind === SyntaxKind.Constructor || + node.kind === SyntaxKind.ConstructSignature + ) { + checkGrammarFunctionLikeDeclaration(node as FunctionLikeDeclaration); + } + + const functionFlags = getFunctionFlags(node as FunctionLikeDeclaration); + if (!(functionFlags & FunctionFlags.Invalid)) { + // Async generators prior to ES2018 require the __await and __asyncGenerator helpers + if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.AsyncGenerator && languageVersion < LanguageFeatureMinimumTarget.AsyncGenerators) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.AsyncGeneratorIncludes); + } + + // Async functions prior to ES2017 require the __awaiter helper + if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async && languageVersion < LanguageFeatureMinimumTarget.AsyncFunctions) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Awaiter); + } + + // Generator functions, Async functions, and Async Generator functions prior to + // ES2015 require the __generator helper + if ((functionFlags & FunctionFlags.AsyncGenerator) !== FunctionFlags.Normal && languageVersion < LanguageFeatureMinimumTarget.Generators) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Generator); + } + } + + checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); + checkUnmatchedJSDocParameters(node); + + forEach(node.parameters, checkParameter); + + // TODO(rbuckton): Should we start checking JSDoc types? + if (node.type) { + checkSourceElement(node.type); + } + + addLazyDiagnostic(checkSignatureDeclarationDiagnostics); + + function checkSignatureDeclarationDiagnostics() { + checkCollisionWithArgumentsInGeneratedCode(node); + + let returnTypeNode = getEffectiveReturnTypeNode(node); + let returnTypeErrorLocation = returnTypeNode; + + if (isInJSFile(node)) { + const typeTag = getJSDocTypeTag(node); + if (typeTag && typeTag.typeExpression && isTypeReferenceNode(typeTag.typeExpression.type)) { + const signature = getSingleCallSignature(getTypeFromTypeNode(typeTag.typeExpression)); + if (signature && signature.declaration) { + returnTypeNode = getEffectiveReturnTypeNode(signature.declaration); + returnTypeErrorLocation = typeTag.typeExpression.type; + } + } + } + + if (noImplicitAny && !returnTypeNode) { + switch (node.kind) { + case SyntaxKind.ConstructSignature: + error(node, Diagnostics.Construct_signature_which_lacks_return_type_annotation_implicitly_has_an_any_return_type); + break; + case SyntaxKind.CallSignature: + error(node, Diagnostics.Call_signature_which_lacks_return_type_annotation_implicitly_has_an_any_return_type); + break; + } + } + + if (returnTypeNode && returnTypeErrorLocation) { + const functionFlags = getFunctionFlags(node as FunctionDeclaration); + if ((functionFlags & (FunctionFlags.Invalid | FunctionFlags.Generator)) === FunctionFlags.Generator) { + const returnType = getTypeFromTypeNode(returnTypeNode); + if (returnType === voidType) { + error(returnTypeErrorLocation, Diagnostics.A_generator_cannot_have_a_void_type_annotation); + } + else { + checkGeneratorInstantiationAssignabilityToReturnType(returnType, functionFlags, returnTypeErrorLocation); + } + } + else if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async) { + checkAsyncFunctionReturnType(node as FunctionLikeDeclaration, returnTypeNode, returnTypeErrorLocation); + } + } + if (node.kind !== SyntaxKind.IndexSignature && node.kind !== SyntaxKind.JSDocFunctionType) { + registerForUnusedIdentifiersCheck(node); + } + } + } + + function checkGeneratorInstantiationAssignabilityToReturnType(returnType: Type, functionFlags: FunctionFlags, errorNode?: TypeNode) { + // Naively, one could check that Generator is assignable to the return type annotation. + // However, that would not catch the error in the following case. + // + // interface BadGenerator extends Iterable, Iterator { } + // function* g(): BadGenerator { } // Iterable and Iterator have different types! + // + const generatorYieldType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Yield, returnType, (functionFlags & FunctionFlags.Async) !== 0) || anyType; + const generatorReturnType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, returnType, (functionFlags & FunctionFlags.Async) !== 0) || generatorYieldType; + const generatorNextType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Next, returnType, (functionFlags & FunctionFlags.Async) !== 0) || unknownType; + const generatorInstantiation = createGeneratorType(generatorYieldType, generatorReturnType, generatorNextType, !!(functionFlags & FunctionFlags.Async)); + + return checkTypeAssignableTo(generatorInstantiation, returnType, errorNode); + } + + function checkClassForDuplicateDeclarations(node: ClassLikeDeclaration) { + const instanceNames = new Map<__String, DeclarationMeaning>(); + const staticNames = new Map<__String, DeclarationMeaning>(); + // instance and static private identifiers share the same scope + const privateIdentifiers = new Map<__String, DeclarationMeaning>(); + for (const member of node.members) { + if (member.kind === SyntaxKind.Constructor) { + for (const param of (member as ConstructorDeclaration).parameters) { + if (isParameterPropertyDeclaration(param, member) && !isBindingPattern(param.name)) { + addName(instanceNames, param.name, param.name.escapedText, DeclarationMeaning.GetOrSetAccessor); + } + } + } + else { + const isStaticMember = isStatic(member); + const name = member.name; + if (!name) { + continue; + } + const isPrivate = isPrivateIdentifier(name); + const privateStaticFlags = isPrivate && isStaticMember ? DeclarationMeaning.PrivateStatic : 0; + const names = isPrivate ? privateIdentifiers : + isStaticMember ? staticNames : + instanceNames; + + const memberName = name && getEffectivePropertyNameForPropertyNameNode(name); + if (memberName) { + switch (member.kind) { + case SyntaxKind.GetAccessor: + addName(names, name, memberName, DeclarationMeaning.GetAccessor | privateStaticFlags); + break; + + case SyntaxKind.SetAccessor: + addName(names, name, memberName, DeclarationMeaning.SetAccessor | privateStaticFlags); + break; + + case SyntaxKind.PropertyDeclaration: + addName(names, name, memberName, DeclarationMeaning.GetOrSetAccessor | privateStaticFlags); + break; + + case SyntaxKind.MethodDeclaration: + addName(names, name, memberName, DeclarationMeaning.Method | privateStaticFlags); + break; + } + } + } + } + + function addName(names: Map<__String, DeclarationMeaning>, location: Node, name: __String, meaning: DeclarationMeaning) { + const prev = names.get(name); + if (prev) { + // For private identifiers, do not allow mixing of static and instance members with the same name + if ((prev & DeclarationMeaning.PrivateStatic) !== (meaning & DeclarationMeaning.PrivateStatic)) { + error(location, Diagnostics.Duplicate_identifier_0_Static_and_instance_elements_cannot_share_the_same_private_name, getTextOfNode(location)); + } + else { + const prevIsMethod = !!(prev & DeclarationMeaning.Method); + const isMethod = !!(meaning & DeclarationMeaning.Method); + if (prevIsMethod || isMethod) { + if (prevIsMethod !== isMethod) { + error(location, Diagnostics.Duplicate_identifier_0, getTextOfNode(location)); + } + // If this is a method/method duplication is might be an overload, so this will be handled when overloads are considered + } + else if (prev & meaning & ~DeclarationMeaning.PrivateStatic) { + error(location, Diagnostics.Duplicate_identifier_0, getTextOfNode(location)); + } + else { + names.set(name, prev | meaning); + } + } + } + else { + names.set(name, meaning); + } + } + } + + /** + * Static members being set on a constructor function may conflict with built-in properties + * of Function. Esp. in ECMAScript 5 there are non-configurable and non-writable + * built-in properties. This check issues a transpile error when a class has a static + * member with the same name as a non-writable built-in property. + * + * @see http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.3 + * @see http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.5 + * @see http://www.ecma-international.org/ecma-262/6.0/#sec-properties-of-the-function-constructor + * @see http://www.ecma-international.org/ecma-262/6.0/#sec-function-instances + */ + function checkClassForStaticPropertyNameConflicts(node: ClassLikeDeclaration) { + for (const member of node.members) { + const memberNameNode = member.name; + const isStaticMember = isStatic(member); + if (isStaticMember && memberNameNode) { + const memberName = getEffectivePropertyNameForPropertyNameNode(memberNameNode); + switch (memberName) { + case "name": + case "length": + case "caller": + case "arguments": + if (useDefineForClassFields) { + break; + } + // fall through + case "prototype": + const message = Diagnostics.Static_property_0_conflicts_with_built_in_property_Function_0_of_constructor_function_1; + const className = getNameOfSymbolAsWritten(getSymbolOfDeclaration(node)); + error(memberNameNode, message, memberName, className); + break; + } + } + } + } + + function checkObjectTypeForDuplicateDeclarations(node: TypeLiteralNode | InterfaceDeclaration) { + const names = new Map(); + for (const member of node.members) { + if (member.kind === SyntaxKind.PropertySignature) { + let memberName: string; + const name = member.name!; + switch (name.kind) { + case SyntaxKind.StringLiteral: + case SyntaxKind.NumericLiteral: + memberName = name.text; + break; + case SyntaxKind.Identifier: + memberName = idText(name); + break; + default: + continue; + } + + if (names.get(memberName)) { + error(getNameOfDeclaration(member.symbol.valueDeclaration), Diagnostics.Duplicate_identifier_0, memberName); + error(member.name, Diagnostics.Duplicate_identifier_0, memberName); + } + else { + names.set(memberName, true); + } + } + } + } + + function checkTypeForDuplicateIndexSignatures(node: ClassLikeDeclaration | InterfaceDeclaration | TypeLiteralNode) { + if (node.kind === SyntaxKind.InterfaceDeclaration) { + const nodeSymbol = getSymbolOfDeclaration(node); + // in case of merging interface declaration it is possible that we'll enter this check procedure several times for every declaration + // to prevent this run check only for the first declaration of a given kind + if (nodeSymbol.declarations && nodeSymbol.declarations.length > 0 && nodeSymbol.declarations[0] !== node) { + return; + } + } + + // TypeScript 1.0 spec (April 2014) + // 3.7.4: An object type can contain at most one string index signature and one numeric index signature. + // 8.5: A class declaration can have at most one string index member declaration and one numeric index member declaration + const indexSymbol = getIndexSymbol(getSymbolOfDeclaration(node)); + if (indexSymbol?.declarations) { + const indexSignatureMap = new Map(); + for (const declaration of (indexSymbol.declarations as IndexSignatureDeclaration[])) { + if (declaration.parameters.length === 1 && declaration.parameters[0].type) { + forEachType(getTypeFromTypeNode(declaration.parameters[0].type), type => { + const entry = indexSignatureMap.get(getTypeId(type)); + if (entry) { + entry.declarations.push(declaration); + } + else { + indexSignatureMap.set(getTypeId(type), { type, declarations: [declaration] }); + } + }); + } + } + indexSignatureMap.forEach(entry => { + if (entry.declarations.length > 1) { + for (const declaration of entry.declarations) { + error(declaration, Diagnostics.Duplicate_index_signature_for_type_0, typeToString(entry.type)); + } + } + }); + } + } + + function checkPropertyDeclaration(node: PropertyDeclaration | PropertySignature) { + // Grammar checking + if (!checkGrammarModifiers(node) && !checkGrammarProperty(node)) checkGrammarComputedPropertyName(node.name); + checkVariableLikeDeclaration(node); + + setNodeLinksForPrivateIdentifierScope(node); + + // property signatures already report "initializer not allowed in ambient context" elsewhere + if (hasSyntacticModifier(node, ModifierFlags.Abstract) && node.kind === SyntaxKind.PropertyDeclaration && node.initializer) { + error(node, Diagnostics.Property_0_cannot_have_an_initializer_because_it_is_marked_abstract, declarationNameToString(node.name)); + } + } + + function checkPropertySignature(node: PropertySignature) { + if (isPrivateIdentifier(node.name)) { + error(node, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + return checkPropertyDeclaration(node); + } + + function checkMethodDeclaration(node: MethodDeclaration | MethodSignature) { + // Grammar checking + if (!checkGrammarMethod(node)) checkGrammarComputedPropertyName(node.name); + + if (isMethodDeclaration(node) && node.asteriskToken && isIdentifier(node.name) && idText(node.name) === "constructor") { + error(node.name, Diagnostics.Class_constructor_may_not_be_a_generator); + } + + // Grammar checking for modifiers is done inside the function checkGrammarFunctionLikeDeclaration + checkFunctionOrMethodDeclaration(node); + + // method signatures already report "implementation not allowed in ambient context" elsewhere + if (hasSyntacticModifier(node, ModifierFlags.Abstract) && node.kind === SyntaxKind.MethodDeclaration && node.body) { + error(node, Diagnostics.Method_0_cannot_have_an_implementation_because_it_is_marked_abstract, declarationNameToString(node.name)); + } + + // Private named methods are only allowed in class declarations + if (isPrivateIdentifier(node.name) && !getContainingClass(node)) { + error(node, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + + setNodeLinksForPrivateIdentifierScope(node); + } + + function setNodeLinksForPrivateIdentifierScope(node: PropertyDeclaration | PropertySignature | MethodDeclaration | MethodSignature | AccessorDeclaration) { + if (isPrivateIdentifier(node.name)) { + if ( + languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators || + !useDefineForClassFields + ) { + for (let lexicalScope = getEnclosingBlockScopeContainer(node); !!lexicalScope; lexicalScope = getEnclosingBlockScopeContainer(lexicalScope)) { + getNodeLinks(lexicalScope).flags |= NodeCheckFlags.ContainsClassWithPrivateIdentifiers; + } + + // If this is a private element in a class expression inside the body of a loop, + // then we must use a block-scoped binding to store the additional variables required + // to transform private elements. + if (isClassExpression(node.parent)) { + const enclosingIterationStatement = getEnclosingIterationStatement(node.parent); + if (enclosingIterationStatement) { + getNodeLinks(node.name).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; + } + } + } + } + } + + function checkClassStaticBlockDeclaration(node: ClassStaticBlockDeclaration) { + checkGrammarModifiers(node); + + forEachChild(node, checkSourceElement); + } + + function checkConstructorDeclaration(node: ConstructorDeclaration) { + // Grammar check on signature of constructor and modifier of the constructor is done in checkSignatureDeclaration function. + checkSignatureDeclaration(node); + // Grammar check for checking only related to constructorDeclaration + if (!checkGrammarConstructorTypeParameters(node)) checkGrammarConstructorTypeAnnotation(node); + + checkSourceElement(node.body); + + const symbol = getSymbolOfDeclaration(node); + const firstDeclaration = getDeclarationOfKind(symbol, node.kind); + + // Only type check the symbol once + if (node === firstDeclaration) { + checkFunctionOrConstructorSymbol(symbol); + } + + // exit early in the case of signature - super checks are not relevant to them + if (nodeIsMissing(node.body)) { + return; + } + + addLazyDiagnostic(checkConstructorDeclarationDiagnostics); + + return; + + function isInstancePropertyWithInitializerOrPrivateIdentifierProperty(n: Node): boolean { + if (isPrivateIdentifierClassElementDeclaration(n)) { + return true; + } + return n.kind === SyntaxKind.PropertyDeclaration && + !isStatic(n) && + !!(n as PropertyDeclaration).initializer; + } + + function checkConstructorDeclarationDiagnostics() { + // TS 1.0 spec (April 2014): 8.3.2 + // Constructors of classes with no extends clause may not contain super calls, whereas + // constructors of derived classes must contain at least one super call somewhere in their function body. + const containingClassDecl = node.parent; + if (getClassExtendsHeritageElement(containingClassDecl)) { + captureLexicalThis(node.parent, containingClassDecl); + const classExtendsNull = classDeclarationExtendsNull(containingClassDecl); + const superCall = findFirstSuperCall(node.body!); + if (superCall) { + if (classExtendsNull) { + error(superCall, Diagnostics.A_constructor_cannot_contain_a_super_call_when_its_class_extends_null); + } + + // A super call must be root-level in a constructor if both of the following are true: + // - The containing class is a derived class. + // - The constructor declares parameter properties + // or the containing class declares instance member variables with initializers. + + const superCallShouldBeRootLevel = !emitStandardClassFields && + (some(node.parent.members, isInstancePropertyWithInitializerOrPrivateIdentifierProperty) || + some(node.parameters, p => hasSyntacticModifier(p, ModifierFlags.ParameterPropertyModifier))); + + if (superCallShouldBeRootLevel) { + // Until we have better flow analysis, it is an error to place the super call within any kind of block or conditional + // See GH #8277 + if (!superCallIsRootLevelInConstructor(superCall, node.body!)) { + error(superCall, Diagnostics.A_super_call_must_be_a_root_level_statement_within_a_constructor_of_a_derived_class_that_contains_initialized_properties_parameter_properties_or_private_identifiers); + } + // Skip past any prologue directives to check statements for referring to 'super' or 'this' before a super call + else { + let superCallStatement: ExpressionStatement | undefined; + + for (const statement of node.body!.statements) { + if (isExpressionStatement(statement) && isSuperCall(skipOuterExpressions(statement.expression))) { + superCallStatement = statement; + break; + } + if (nodeImmediatelyReferencesSuperOrThis(statement)) { + break; + } + } + + // Until we have better flow analysis, it is an error to place the super call within any kind of block or conditional + // See GH #8277 + if (superCallStatement === undefined) { + error(node, Diagnostics.A_super_call_must_be_the_first_statement_in_the_constructor_to_refer_to_super_or_this_when_a_derived_class_contains_initialized_properties_parameter_properties_or_private_identifiers); + } + } + } + } + else if (!classExtendsNull) { + error(node, Diagnostics.Constructors_for_derived_classes_must_contain_a_super_call); + } + } + } + } + + function superCallIsRootLevelInConstructor(superCall: Node, body: Block) { + const superCallParent = walkUpParenthesizedExpressions(superCall.parent); + return isExpressionStatement(superCallParent) && superCallParent.parent === body; + } + + function nodeImmediatelyReferencesSuperOrThis(node: Node): boolean { + if (node.kind === SyntaxKind.SuperKeyword || node.kind === SyntaxKind.ThisKeyword) { + return true; + } + + if (isThisContainerOrFunctionBlock(node)) { + return false; + } + + return !!forEachChild(node, nodeImmediatelyReferencesSuperOrThis); + } + + function checkAccessorDeclaration(node: AccessorDeclaration) { + if (isIdentifier(node.name) && idText(node.name) === "constructor" && isClassLike(node.parent)) { + error(node.name, Diagnostics.Class_constructor_may_not_be_an_accessor); + } + addLazyDiagnostic(checkAccessorDeclarationDiagnostics); + checkSourceElement(node.body); + setNodeLinksForPrivateIdentifierScope(node); + + function checkAccessorDeclarationDiagnostics() { + // Grammar checking accessors + if (!checkGrammarFunctionLikeDeclaration(node) && !checkGrammarAccessor(node)) checkGrammarComputedPropertyName(node.name); + + checkDecorators(node); + checkSignatureDeclaration(node); + if (node.kind === SyntaxKind.GetAccessor) { + if (!(node.flags & NodeFlags.Ambient) && nodeIsPresent(node.body) && (node.flags & NodeFlags.HasImplicitReturn)) { + if (!(node.flags & NodeFlags.HasExplicitReturn)) { + error(node.name, Diagnostics.A_get_accessor_must_return_a_value); + } + } + } + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + } + + if (hasBindableName(node)) { + // TypeScript 1.0 spec (April 2014): 8.4.3 + // Accessors for the same member name must specify the same accessibility. + const symbol = getSymbolOfDeclaration(node); + const getter = getDeclarationOfKind(symbol, SyntaxKind.GetAccessor); + const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor); + if (getter && setter && !(getNodeCheckFlags(getter) & NodeCheckFlags.TypeChecked)) { + getNodeLinks(getter).flags |= NodeCheckFlags.TypeChecked; + const getterFlags = getEffectiveModifierFlags(getter); + const setterFlags = getEffectiveModifierFlags(setter); + if ((getterFlags & ModifierFlags.Abstract) !== (setterFlags & ModifierFlags.Abstract)) { + error(getter.name, Diagnostics.Accessors_must_both_be_abstract_or_non_abstract); + error(setter.name, Diagnostics.Accessors_must_both_be_abstract_or_non_abstract); + } + if ( + ((getterFlags & ModifierFlags.Protected) && !(setterFlags & (ModifierFlags.Protected | ModifierFlags.Private))) || + ((getterFlags & ModifierFlags.Private) && !(setterFlags & ModifierFlags.Private)) + ) { + error(getter.name, Diagnostics.A_get_accessor_must_be_at_least_as_accessible_as_the_setter); + error(setter.name, Diagnostics.A_get_accessor_must_be_at_least_as_accessible_as_the_setter); + } + } + } + const returnType = getTypeOfAccessors(getSymbolOfDeclaration(node)); + if (node.kind === SyntaxKind.GetAccessor) { + checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType); + } + } + } + + function checkMissingDeclaration(node: Node) { + checkDecorators(node); + } + + function getEffectiveTypeArgumentAtIndex(node: TypeReferenceNode | ExpressionWithTypeArguments, typeParameters: readonly TypeParameter[], index: number): Type { + if (node.typeArguments && index < node.typeArguments.length) { + return getTypeFromTypeNode(node.typeArguments[index]); + } + return getEffectiveTypeArguments(node, typeParameters)[index]; + } + + function getEffectiveTypeArguments(node: TypeReferenceNode | ExpressionWithTypeArguments | NodeWithTypeArguments, typeParameters: readonly TypeParameter[]): Type[] { + return fillMissingTypeArguments(map(node.typeArguments!, getTypeFromTypeNode), typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(node)); + } + + function checkTypeArgumentConstraints(node: TypeReferenceNode | ExpressionWithTypeArguments | NodeWithTypeArguments, typeParameters: readonly TypeParameter[]): boolean { + let typeArguments: Type[] | undefined; + let mapper: TypeMapper | undefined; + let result = true; + for (let i = 0; i < typeParameters.length; i++) { + const constraint = getConstraintOfTypeParameter(typeParameters[i]); + if (constraint) { + if (!typeArguments) { + typeArguments = getEffectiveTypeArguments(node, typeParameters); + mapper = createTypeMapper(typeParameters, typeArguments); + } + result = result && checkTypeAssignableTo( + typeArguments[i], + instantiateType(constraint, mapper), + node.typeArguments![i], + Diagnostics.Type_0_does_not_satisfy_the_constraint_1, + ); + } + } + return result; + } + + function getTypeParametersForTypeAndSymbol(type: Type, symbol: Symbol) { + if (!isErrorType(type)) { + return symbol.flags & SymbolFlags.TypeAlias && getSymbolLinks(symbol).typeParameters || + (getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).target.localTypeParameters : undefined); + } + return undefined; + } + + function getTypeParametersForTypeReferenceOrImport(node: TypeReferenceNode | ExpressionWithTypeArguments | ImportTypeNode) { + const type = getTypeFromTypeNode(node); + if (!isErrorType(type)) { + const symbol = getNodeLinks(node).resolvedSymbol; + if (symbol) { + return getTypeParametersForTypeAndSymbol(type, symbol); + } + } + return undefined; + } + + function checkTypeReferenceNode(node: TypeReferenceNode | ExpressionWithTypeArguments) { + checkGrammarTypeArguments(node, node.typeArguments); + if (node.kind === SyntaxKind.TypeReference && !isInJSFile(node) && !isInJSDoc(node) && node.typeArguments && node.typeName.end !== node.typeArguments.pos) { + // If there was a token between the type name and the type arguments, check if it was a DotToken + const sourceFile = getSourceFileOfNode(node); + if (scanTokenAtPosition(sourceFile, node.typeName.end) === SyntaxKind.DotToken) { + grammarErrorAtPos(node, skipTrivia(sourceFile.text, node.typeName.end), 1, Diagnostics.JSDoc_types_can_only_be_used_inside_documentation_comments); + } + } + forEach(node.typeArguments, checkSourceElement); + checkTypeReferenceOrImport(node); + } + + function checkTypeReferenceOrImport(node: TypeReferenceNode | ExpressionWithTypeArguments | ImportTypeNode) { + const type = getTypeFromTypeNode(node); + if (!isErrorType(type)) { + if (node.typeArguments) { + addLazyDiagnostic(() => { + const typeParameters = getTypeParametersForTypeReferenceOrImport(node); + if (typeParameters) { + checkTypeArgumentConstraints(node, typeParameters); + } + }); + } + const symbol = getNodeLinks(node).resolvedSymbol; + if (symbol) { + if (some(symbol.declarations, d => isTypeDeclaration(d) && !!(d.flags & NodeFlags.Deprecated))) { + addDeprecatedSuggestion( + getDeprecatedSuggestionNode(node), + symbol.declarations!, + symbol.escapedName as string, + ); + } + } + } + } + + function getTypeArgumentConstraint(node: TypeNode): Type | undefined { + const typeReferenceNode = tryCast(node.parent, isTypeReferenceType); + if (!typeReferenceNode) return undefined; + const typeParameters = getTypeParametersForTypeReferenceOrImport(typeReferenceNode); + if (!typeParameters) return undefined; + const constraint = getConstraintOfTypeParameter(typeParameters[typeReferenceNode.typeArguments!.indexOf(node)]); + return constraint && instantiateType(constraint, createTypeMapper(typeParameters, getEffectiveTypeArguments(typeReferenceNode, typeParameters))); + } + + function checkTypeQuery(node: TypeQueryNode) { + getTypeFromTypeQueryNode(node); + } + + function checkTypeLiteral(node: TypeLiteralNode) { + forEach(node.members, checkSourceElement); + addLazyDiagnostic(checkTypeLiteralDiagnostics); + + function checkTypeLiteralDiagnostics() { + const type = getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node); + checkIndexConstraints(type, type.symbol); + checkTypeForDuplicateIndexSignatures(node); + checkObjectTypeForDuplicateDeclarations(node); + } + } + + function checkArrayType(node: ArrayTypeNode) { + checkSourceElement(node.elementType); + } + + function checkTupleType(node: TupleTypeNode) { + let seenOptionalElement = false; + let seenRestElement = false; + for (const e of node.elements) { + let flags = getTupleElementFlags(e); + if (flags & ElementFlags.Variadic) { + const type = getTypeFromTypeNode((e as RestTypeNode | NamedTupleMember).type); + if (!isArrayLikeType(type)) { + error(e, Diagnostics.A_rest_element_type_must_be_an_array_type); + break; + } + if (isArrayType(type) || isTupleType(type) && type.target.combinedFlags & ElementFlags.Rest) { + flags |= ElementFlags.Rest; + } + } + if (flags & ElementFlags.Rest) { + if (seenRestElement) { + grammarErrorOnNode(e, Diagnostics.A_rest_element_cannot_follow_another_rest_element); + break; + } + seenRestElement = true; + } + else if (flags & ElementFlags.Optional) { + if (seenRestElement) { + grammarErrorOnNode(e, Diagnostics.An_optional_element_cannot_follow_a_rest_element); + break; + } + seenOptionalElement = true; + } + else if (flags & ElementFlags.Required && seenOptionalElement) { + grammarErrorOnNode(e, Diagnostics.A_required_element_cannot_follow_an_optional_element); + break; + } + } + forEach(node.elements, checkSourceElement); + getTypeFromTypeNode(node); + } + + function checkUnionOrIntersectionType(node: UnionOrIntersectionTypeNode) { + forEach(node.types, checkSourceElement); + getTypeFromTypeNode(node); + } + + function checkIndexedAccessIndexType(type: Type, accessNode: IndexedAccessTypeNode | ElementAccessExpression) { + if (!(type.flags & TypeFlags.IndexedAccess)) { + return type; + } + // Check if the index type is assignable to 'keyof T' for the object type. + const objectType = (type as IndexedAccessType).objectType; + const indexType = (type as IndexedAccessType).indexType; + // skip index type deferral on remapping mapped types + const objectIndexType = isGenericMappedType(objectType) && getMappedTypeNameTypeKind(objectType) === MappedTypeNameTypeKind.Remapping + ? getIndexTypeForMappedType(objectType, IndexFlags.None) + : getIndexType(objectType, IndexFlags.None); + const hasNumberIndexInfo = !!getIndexInfoOfType(objectType, numberType); + if (everyType(indexType, t => isTypeAssignableTo(t, objectIndexType) || hasNumberIndexInfo && isApplicableIndexType(t, numberType))) { + if ( + accessNode.kind === SyntaxKind.ElementAccessExpression && isAssignmentTarget(accessNode) && + getObjectFlags(objectType) & ObjectFlags.Mapped && getMappedTypeModifiers(objectType as MappedType) & MappedTypeModifiers.IncludeReadonly + ) { + error(accessNode, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType)); + } + return type; + } + if (isGenericObjectType(objectType)) { + const propertyName = getPropertyNameFromIndex(indexType, accessNode); + if (propertyName) { + const propertySymbol = forEachType(getApparentType(objectType), t => getPropertyOfType(t, propertyName)); + if (propertySymbol && getDeclarationModifierFlagsFromSymbol(propertySymbol) & ModifierFlags.NonPublicAccessibilityModifier) { + error(accessNode, Diagnostics.Private_or_protected_member_0_cannot_be_accessed_on_a_type_parameter, unescapeLeadingUnderscores(propertyName)); + return errorType; + } + } + } + error(accessNode, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(objectType)); + return errorType; + } + + function checkIndexedAccessType(node: IndexedAccessTypeNode) { + checkSourceElement(node.objectType); + checkSourceElement(node.indexType); + checkIndexedAccessIndexType(getTypeFromIndexedAccessTypeNode(node), node); + } + + function checkMappedType(node: MappedTypeNode) { + checkGrammarMappedType(node); + checkSourceElement(node.typeParameter); + checkSourceElement(node.nameType); + checkSourceElement(node.type); + + if (!node.type) { + reportImplicitAny(node, anyType); + } + + const type = getTypeFromMappedTypeNode(node) as MappedType; + const nameType = getNameTypeFromMappedType(type); + if (nameType) { + checkTypeAssignableTo(nameType, stringNumberSymbolType, node.nameType); + } + else { + const constraintType = getConstraintTypeFromMappedType(type); + checkTypeAssignableTo(constraintType, stringNumberSymbolType, getEffectiveConstraintOfTypeParameter(node.typeParameter)); + } + } + + function checkGrammarMappedType(node: MappedTypeNode) { + if (node.members?.length) { + return grammarErrorOnNode(node.members[0], Diagnostics.A_mapped_type_may_not_declare_properties_or_methods); + } + } + + function checkThisType(node: ThisTypeNode) { + getTypeFromThisTypeNode(node); + } + + function checkTypeOperator(node: TypeOperatorNode) { + checkGrammarTypeOperatorNode(node); + checkSourceElement(node.type); + } + + function checkConditionalType(node: ConditionalTypeNode) { + forEachChild(node, checkSourceElement); + } + + function checkInferType(node: InferTypeNode) { + if (!findAncestor(node, n => n.parent && n.parent.kind === SyntaxKind.ConditionalType && (n.parent as ConditionalTypeNode).extendsType === n)) { + grammarErrorOnNode(node, Diagnostics.infer_declarations_are_only_permitted_in_the_extends_clause_of_a_conditional_type); + } + checkSourceElement(node.typeParameter); + const symbol = getSymbolOfDeclaration(node.typeParameter); + if (symbol.declarations && symbol.declarations.length > 1) { + const links = getSymbolLinks(symbol); + if (!links.typeParametersChecked) { + links.typeParametersChecked = true; + const typeParameter = getDeclaredTypeOfTypeParameter(symbol); + const declarations: TypeParameterDeclaration[] = getDeclarationsOfKind(symbol, SyntaxKind.TypeParameter); + if (!areTypeParametersIdentical(declarations, [typeParameter], decl => [decl])) { + // Report an error on every conflicting declaration. + const name = symbolToString(symbol); + for (const declaration of declarations) { + error(declaration.name, Diagnostics.All_declarations_of_0_must_have_identical_constraints, name); + } + } + } + } + registerForUnusedIdentifiersCheck(node); + } + + function checkTemplateLiteralType(node: TemplateLiteralTypeNode) { + for (const span of node.templateSpans) { + checkSourceElement(span.type); + const type = getTypeFromTypeNode(span.type); + checkTypeAssignableTo(type, templateConstraintType, span.type); + } + getTypeFromTypeNode(node); + } + + function checkImportType(node: ImportTypeNode) { + checkSourceElement(node.argument); + + if (node.attributes) { + getResolutionModeOverride(node.attributes, grammarErrorOnNode); + } + checkTypeReferenceOrImport(node); + } + + function checkNamedTupleMember(node: NamedTupleMember) { + if (node.dotDotDotToken && node.questionToken) { + grammarErrorOnNode(node, Diagnostics.A_tuple_member_cannot_be_both_optional_and_rest); + } + if (node.type.kind === SyntaxKind.OptionalType) { + grammarErrorOnNode(node.type, Diagnostics.A_labeled_tuple_element_is_declared_as_optional_with_a_question_mark_after_the_name_and_before_the_colon_rather_than_after_the_type); + } + if (node.type.kind === SyntaxKind.RestType) { + grammarErrorOnNode(node.type, Diagnostics.A_labeled_tuple_element_is_declared_as_rest_with_a_before_the_name_rather_than_before_the_type); + } + checkSourceElement(node.type); + getTypeFromTypeNode(node); + } + + function isPrivateWithinAmbient(node: Node): boolean { + return (hasEffectiveModifier(node, ModifierFlags.Private) || isPrivateIdentifierClassElementDeclaration(node)) && !!(node.flags & NodeFlags.Ambient); + } + + function getEffectiveDeclarationFlags(n: Declaration, flagsToCheck: ModifierFlags): ModifierFlags { + let flags = getCombinedModifierFlagsCached(n); + + // children of classes (even ambient classes) should not be marked as ambient or export + // because those flags have no useful semantics there. + if ( + n.parent.kind !== SyntaxKind.InterfaceDeclaration && + n.parent.kind !== SyntaxKind.ClassDeclaration && + n.parent.kind !== SyntaxKind.ClassExpression && + n.flags & NodeFlags.Ambient + ) { + const container = getEnclosingContainer(n); + if ((container && container.flags & NodeFlags.ExportContext) && !(flags & ModifierFlags.Ambient) && !(isModuleBlock(n.parent) && isModuleDeclaration(n.parent.parent) && isGlobalScopeAugmentation(n.parent.parent))) { + // It is nested in an ambient export context, which means it is automatically exported + flags |= ModifierFlags.Export; + } + flags |= ModifierFlags.Ambient; + } + + return flags & flagsToCheck; + } + + function checkFunctionOrConstructorSymbol(symbol: Symbol): void { + addLazyDiagnostic(() => checkFunctionOrConstructorSymbolWorker(symbol)); + } + + function checkFunctionOrConstructorSymbolWorker(symbol: Symbol): void { + function getCanonicalOverload(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined): Declaration { + // Consider the canonical set of flags to be the flags of the bodyDeclaration or the first declaration + // Error on all deviations from this canonical set of flags + // The caveat is that if some overloads are defined in lib.d.ts, we don't want to + // report the errors on those. To achieve this, we will say that the implementation is + // the canonical signature only if it is in the same container as the first overload + const implementationSharesContainerWithFirstOverload = implementation !== undefined && implementation.parent === overloads[0].parent; + return implementationSharesContainerWithFirstOverload ? implementation : overloads[0]; + } + + function checkFlagAgreementBetweenOverloads(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined, flagsToCheck: ModifierFlags, someOverloadFlags: ModifierFlags, allOverloadFlags: ModifierFlags): void { + // Error if some overloads have a flag that is not shared by all overloads. To find the + // deviations, we XOR someOverloadFlags with allOverloadFlags + const someButNotAllOverloadFlags = someOverloadFlags ^ allOverloadFlags; + if (someButNotAllOverloadFlags !== 0) { + const canonicalFlags = getEffectiveDeclarationFlags(getCanonicalOverload(overloads, implementation), flagsToCheck); + forEach(overloads, o => { + const deviation = getEffectiveDeclarationFlags(o, flagsToCheck) ^ canonicalFlags; + if (deviation & ModifierFlags.Export) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_exported_or_non_exported); + } + else if (deviation & ModifierFlags.Ambient) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_ambient_or_non_ambient); + } + else if (deviation & (ModifierFlags.Private | ModifierFlags.Protected)) { + error(getNameOfDeclaration(o) || o, Diagnostics.Overload_signatures_must_all_be_public_private_or_protected); + } + else if (deviation & ModifierFlags.Abstract) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_abstract_or_non_abstract); + } + }); + } + } + + function checkQuestionTokenAgreementBetweenOverloads(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined, someHaveQuestionToken: boolean, allHaveQuestionToken: boolean): void { + if (someHaveQuestionToken !== allHaveQuestionToken) { + const canonicalHasQuestionToken = hasQuestionToken(getCanonicalOverload(overloads, implementation)); + forEach(overloads, o => { + const deviation = hasQuestionToken(o) !== canonicalHasQuestionToken; + if (deviation) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_optional_or_required); + } + }); + } + } + + const flagsToCheck: ModifierFlags = ModifierFlags.Export | ModifierFlags.Ambient | ModifierFlags.Private | ModifierFlags.Protected | ModifierFlags.Abstract; + let someNodeFlags: ModifierFlags = ModifierFlags.None; + let allNodeFlags = flagsToCheck; + let someHaveQuestionToken = false; + let allHaveQuestionToken = true; + let hasOverloads = false; + let bodyDeclaration: FunctionLikeDeclaration | undefined; + let lastSeenNonAmbientDeclaration: FunctionLikeDeclaration | undefined; + let previousDeclaration: SignatureDeclaration | undefined; + + const declarations = symbol.declarations; + const isConstructor = (symbol.flags & SymbolFlags.Constructor) !== 0; + + function reportImplementationExpectedError(node: SignatureDeclaration): void { + if (node.name && nodeIsMissing(node.name)) { + return; + } + + let seen = false; + const subsequentNode = forEachChild(node.parent, c => { + if (seen) { + return c; + } + else { + seen = c === node; + } + }); + // We may be here because of some extra nodes between overloads that could not be parsed into a valid node. + // In this case the subsequent node is not really consecutive (.pos !== node.end), and we must ignore it here. + if (subsequentNode && subsequentNode.pos === node.end) { + if (subsequentNode.kind === node.kind) { + const errorNode: Node = (subsequentNode as FunctionLikeDeclaration).name || subsequentNode; + const subsequentName = (subsequentNode as FunctionLikeDeclaration).name; + if ( + node.name && subsequentName && ( + // both are private identifiers + isPrivateIdentifier(node.name) && isPrivateIdentifier(subsequentName) && node.name.escapedText === subsequentName.escapedText || + // Both are computed property names + isComputedPropertyName(node.name) && isComputedPropertyName(subsequentName) && isTypeIdenticalTo(checkComputedPropertyName(node.name), checkComputedPropertyName(subsequentName)) || + // Both are literal property names that are the same. + isPropertyNameLiteral(node.name) && isPropertyNameLiteral(subsequentName) && + getEscapedTextOfIdentifierOrLiteral(node.name) === getEscapedTextOfIdentifierOrLiteral(subsequentName) + ) + ) { + const reportError = (node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature) && + isStatic(node) !== isStatic(subsequentNode); + // we can get here in two cases + // 1. mixed static and instance class members + // 2. something with the same name was defined before the set of overloads that prevents them from merging + // here we'll report error only for the first case since for second we should already report error in binder + if (reportError) { + const diagnostic = isStatic(node) ? Diagnostics.Function_overload_must_be_static : Diagnostics.Function_overload_must_not_be_static; + error(errorNode, diagnostic); + } + return; + } + if (nodeIsPresent((subsequentNode as FunctionLikeDeclaration).body)) { + error(errorNode, Diagnostics.Function_implementation_name_must_be_0, declarationNameToString(node.name)); + return; + } + } + } + const errorNode: Node = node.name || node; + if (isConstructor) { + error(errorNode, Diagnostics.Constructor_implementation_is_missing); + } + else { + // Report different errors regarding non-consecutive blocks of declarations depending on whether + // the node in question is abstract. + if (hasSyntacticModifier(node, ModifierFlags.Abstract)) { + error(errorNode, Diagnostics.All_declarations_of_an_abstract_method_must_be_consecutive); + } + else { + error(errorNode, Diagnostics.Function_implementation_is_missing_or_not_immediately_following_the_declaration); + } + } + } + + let duplicateFunctionDeclaration = false; + let multipleConstructorImplementation = false; + let hasNonAmbientClass = false; + const functionDeclarations = [] as Declaration[]; + if (declarations) { + for (const current of declarations) { + const node = current as SignatureDeclaration | ClassDeclaration | ClassExpression; + const inAmbientContext = node.flags & NodeFlags.Ambient; + const inAmbientContextOrInterface = node.parent && (node.parent.kind === SyntaxKind.InterfaceDeclaration || node.parent.kind === SyntaxKind.TypeLiteral) || inAmbientContext; + if (inAmbientContextOrInterface) { + // check if declarations are consecutive only if they are non-ambient + // 1. ambient declarations can be interleaved + // i.e. this is legal + // declare function foo(); + // declare function bar(); + // declare function foo(); + // 2. mixing ambient and non-ambient declarations is a separate error that will be reported - do not want to report an extra one + previousDeclaration = undefined; + } + + if ((node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression) && !inAmbientContext) { + hasNonAmbientClass = true; + } + + if (node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature || node.kind === SyntaxKind.Constructor) { + functionDeclarations.push(node); + const currentNodeFlags = getEffectiveDeclarationFlags(node, flagsToCheck); + someNodeFlags |= currentNodeFlags; + allNodeFlags &= currentNodeFlags; + someHaveQuestionToken = someHaveQuestionToken || hasQuestionToken(node); + allHaveQuestionToken = allHaveQuestionToken && hasQuestionToken(node); + const bodyIsPresent = nodeIsPresent((node as FunctionLikeDeclaration).body); + + if (bodyIsPresent && bodyDeclaration) { + if (isConstructor) { + multipleConstructorImplementation = true; + } + else { + duplicateFunctionDeclaration = true; + } + } + else if (previousDeclaration?.parent === node.parent && previousDeclaration.end !== node.pos) { + reportImplementationExpectedError(previousDeclaration); + } + + if (bodyIsPresent) { + if (!bodyDeclaration) { + bodyDeclaration = node as FunctionLikeDeclaration; + } + } + else { + hasOverloads = true; + } + + previousDeclaration = node; + + if (!inAmbientContextOrInterface) { + lastSeenNonAmbientDeclaration = node as FunctionLikeDeclaration; + } + } + if (isInJSFile(current) && isFunctionLike(current) && current.jsDoc) { + hasOverloads = length(getJSDocOverloadTags(current)) > 0; + } + } + } + + if (multipleConstructorImplementation) { + forEach(functionDeclarations, declaration => { + error(declaration, Diagnostics.Multiple_constructor_implementations_are_not_allowed); + }); + } + + if (duplicateFunctionDeclaration) { + forEach(functionDeclarations, declaration => { + error(getNameOfDeclaration(declaration) || declaration, Diagnostics.Duplicate_function_implementation); + }); + } + + if (hasNonAmbientClass && !isConstructor && symbol.flags & SymbolFlags.Function && declarations) { + const relatedDiagnostics = filter(declarations, d => d.kind === SyntaxKind.ClassDeclaration) + .map(d => createDiagnosticForNode(d, Diagnostics.Consider_adding_a_declare_modifier_to_this_class)); + + forEach(declarations, declaration => { + const diagnostic = declaration.kind === SyntaxKind.ClassDeclaration + ? Diagnostics.Class_declaration_cannot_implement_overload_list_for_0 + : declaration.kind === SyntaxKind.FunctionDeclaration + ? Diagnostics.Function_with_bodies_can_only_merge_with_classes_that_are_ambient + : undefined; + if (diagnostic) { + addRelatedInfo( + error(getNameOfDeclaration(declaration) || declaration, diagnostic, symbolName(symbol)), + ...relatedDiagnostics, + ); + } + }); + } + + // Abstract methods can't have an implementation -- in particular, they don't need one. + if ( + lastSeenNonAmbientDeclaration && !lastSeenNonAmbientDeclaration.body && + !hasSyntacticModifier(lastSeenNonAmbientDeclaration, ModifierFlags.Abstract) && !lastSeenNonAmbientDeclaration.questionToken + ) { + reportImplementationExpectedError(lastSeenNonAmbientDeclaration); + } + + if (hasOverloads) { + if (declarations) { + checkFlagAgreementBetweenOverloads(declarations, bodyDeclaration, flagsToCheck, someNodeFlags, allNodeFlags); + checkQuestionTokenAgreementBetweenOverloads(declarations, bodyDeclaration, someHaveQuestionToken, allHaveQuestionToken); + } + + if (bodyDeclaration) { + const signatures = getSignaturesOfSymbol(symbol); + const bodySignature = getSignatureFromDeclaration(bodyDeclaration); + for (const signature of signatures) { + if (!isImplementationCompatibleWithOverload(bodySignature, signature)) { + const errorNode = signature.declaration && isJSDocSignature(signature.declaration) + ? (signature.declaration.parent as JSDocOverloadTag | JSDocCallbackTag).tagName + : signature.declaration; + addRelatedInfo( + error(errorNode, Diagnostics.This_overload_signature_is_not_compatible_with_its_implementation_signature), + createDiagnosticForNode(bodyDeclaration, Diagnostics.The_implementation_signature_is_declared_here), + ); + break; + } + } + } + } + } + + function checkExportsOnMergedDeclarations(node: Declaration): void { + addLazyDiagnostic(() => checkExportsOnMergedDeclarationsWorker(node)); + } + + function checkExportsOnMergedDeclarationsWorker(node: Declaration): void { + // if localSymbol is defined on node then node itself is exported - check is required + let symbol = node.localSymbol; + if (!symbol) { + // local symbol is undefined => this declaration is non-exported. + // however symbol might contain other declarations that are exported + symbol = getSymbolOfDeclaration(node)!; + if (!symbol.exportSymbol) { + // this is a pure local symbol (all declarations are non-exported) - no need to check anything + return; + } + } + + // run the check only for the first declaration in the list + if (getDeclarationOfKind(symbol, node.kind) !== node) { + return; + } + + let exportedDeclarationSpaces = DeclarationSpaces.None; + let nonExportedDeclarationSpaces = DeclarationSpaces.None; + let defaultExportedDeclarationSpaces = DeclarationSpaces.None; + for (const d of symbol.declarations!) { + const declarationSpaces = getDeclarationSpaces(d); + const effectiveDeclarationFlags = getEffectiveDeclarationFlags(d, ModifierFlags.Export | ModifierFlags.Default); + + if (effectiveDeclarationFlags & ModifierFlags.Export) { + if (effectiveDeclarationFlags & ModifierFlags.Default) { + defaultExportedDeclarationSpaces |= declarationSpaces; + } + else { + exportedDeclarationSpaces |= declarationSpaces; + } + } + else { + nonExportedDeclarationSpaces |= declarationSpaces; + } + } + + // Spaces for anything not declared a 'default export'. + const nonDefaultExportedDeclarationSpaces = exportedDeclarationSpaces | nonExportedDeclarationSpaces; + + const commonDeclarationSpacesForExportsAndLocals = exportedDeclarationSpaces & nonExportedDeclarationSpaces; + const commonDeclarationSpacesForDefaultAndNonDefault = defaultExportedDeclarationSpaces & nonDefaultExportedDeclarationSpaces; + + if (commonDeclarationSpacesForExportsAndLocals || commonDeclarationSpacesForDefaultAndNonDefault) { + // declaration spaces for exported and non-exported declarations intersect + for (const d of symbol.declarations!) { + const declarationSpaces = getDeclarationSpaces(d); + + const name = getNameOfDeclaration(d); + // Only error on the declarations that contributed to the intersecting spaces. + if (declarationSpaces & commonDeclarationSpacesForDefaultAndNonDefault) { + error(name, Diagnostics.Merged_declaration_0_cannot_include_a_default_export_declaration_Consider_adding_a_separate_export_default_0_declaration_instead, declarationNameToString(name)); + } + else if (declarationSpaces & commonDeclarationSpacesForExportsAndLocals) { + error(name, Diagnostics.Individual_declarations_in_merged_declaration_0_must_be_all_exported_or_all_local, declarationNameToString(name)); + } + } + } + + function getDeclarationSpaces(decl: Declaration): DeclarationSpaces { + let d = decl as Node; + switch (d.kind) { + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + + // A jsdoc typedef and callback are, by definition, type aliases. + // falls through + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.JSDocEnumTag: + return DeclarationSpaces.ExportType; + case SyntaxKind.ModuleDeclaration: + return isAmbientModule(d as ModuleDeclaration) || getModuleInstanceState(d as ModuleDeclaration) !== ModuleInstanceState.NonInstantiated + ? DeclarationSpaces.ExportNamespace | DeclarationSpaces.ExportValue + : DeclarationSpaces.ExportNamespace; + case SyntaxKind.ClassDeclaration: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.EnumMember: + return DeclarationSpaces.ExportType | DeclarationSpaces.ExportValue; + case SyntaxKind.SourceFile: + return DeclarationSpaces.ExportType | DeclarationSpaces.ExportValue | DeclarationSpaces.ExportNamespace; + case SyntaxKind.ExportAssignment: + case SyntaxKind.BinaryExpression: + const node = d as ExportAssignment | BinaryExpression; + const expression = isExportAssignment(node) ? node.expression : node.right; + // Export assigned entity name expressions act as aliases and should fall through, otherwise they export values + if (!isEntityNameExpression(expression)) { + return DeclarationSpaces.ExportValue; + } + d = expression; + + // The below options all declare an Alias, which is allowed to merge with other values within the importing module. + // falls through + case SyntaxKind.ImportEqualsDeclaration: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportClause: + let result = DeclarationSpaces.None; + const target = resolveAlias(getSymbolOfDeclaration(d as ImportEqualsDeclaration | NamespaceImport | ImportClause | ExportAssignment | BinaryExpression)); + forEach(target.declarations, d => { + result |= getDeclarationSpaces(d); + }); + return result; + case SyntaxKind.VariableDeclaration: + case SyntaxKind.BindingElement: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.ImportSpecifier: // https://github.com/Microsoft/TypeScript/pull/7591 + case SyntaxKind.Identifier: // https://github.com/microsoft/TypeScript/issues/36098 + // Identifiers are used as declarations of assignment declarations whose parents may be + // SyntaxKind.CallExpression - `Object.defineProperty(thing, "aField", {value: 42});` + // SyntaxKind.ElementAccessExpression - `thing["aField"] = 42;` or `thing["aField"];` (with a doc comment on it) + // or SyntaxKind.PropertyAccessExpression - `thing.aField = 42;` + // all of which are pretty much always values, or at least imply a value meaning. + // It may be apprpriate to treat these as aliases in the future. + return DeclarationSpaces.ExportValue; + case SyntaxKind.MethodSignature: + case SyntaxKind.PropertySignature: + return DeclarationSpaces.ExportType; + default: + return Debug.failBadSyntaxKind(d); + } + } + } + + function getAwaitedTypeOfPromise(type: Type, errorNode?: Node, diagnosticMessage?: DiagnosticMessage, ...args: DiagnosticArguments): Type | undefined { + const promisedType = getPromisedTypeOfPromise(type, errorNode); + return promisedType && getAwaitedType(promisedType, errorNode, diagnosticMessage, ...args); + } + + /** + * Gets the "promised type" of a promise. + * @param type The type of the promise. + * @remarks The "promised type" of a type is the type of the "value" parameter of the "onfulfilled" callback. + */ + function getPromisedTypeOfPromise(type: Type, errorNode?: Node, thisTypeForErrorOut?: { value?: Type; }): Type | undefined { + // + // { // type + // then( // thenFunction + // onfulfilled: ( // onfulfilledParameterType + // value: T // valueParameterType + // ) => any + // ): any; + // } + // + + if (isTypeAny(type)) { + return undefined; + } + + const typeAsPromise = type as PromiseOrAwaitableType; + if (typeAsPromise.promisedTypeOfPromise) { + return typeAsPromise.promisedTypeOfPromise; + } + + if (isReferenceToType(type, getGlobalPromiseType(/*reportErrors*/ false))) { + return typeAsPromise.promisedTypeOfPromise = getTypeArguments(type as GenericType)[0]; + } + + // primitives with a `{ then() }` won't be unwrapped/adopted. + if (allTypesAssignableToKind(getBaseConstraintOrType(type), TypeFlags.Primitive | TypeFlags.Never)) { + return undefined; + } + + const thenFunction = getTypeOfPropertyOfType(type, "then" as __String)!; // TODO: GH#18217 + if (isTypeAny(thenFunction)) { + return undefined; + } + + const thenSignatures = thenFunction ? getSignaturesOfType(thenFunction, SignatureKind.Call) : emptyArray; + if (thenSignatures.length === 0) { + if (errorNode) { + error(errorNode, Diagnostics.A_promise_must_have_a_then_method); + } + return undefined; + } + + let thisTypeForError: Type | undefined; + let candidates: Signature[] | undefined; + for (const thenSignature of thenSignatures) { + const thisType = getThisTypeOfSignature(thenSignature); + if (thisType && thisType !== voidType && !isTypeRelatedTo(type, thisType, subtypeRelation)) { + thisTypeForError = thisType; + } + else { + candidates = append(candidates, thenSignature); + } + } + + if (!candidates) { + Debug.assertIsDefined(thisTypeForError); + if (thisTypeForErrorOut) { + thisTypeForErrorOut.value = thisTypeForError; + } + if (errorNode) { + error(errorNode, Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1, typeToString(type), typeToString(thisTypeForError)); + } + return undefined; + } + + const onfulfilledParameterType = getTypeWithFacts(getUnionType(map(candidates, getTypeOfFirstParameterOfSignature)), TypeFacts.NEUndefinedOrNull); + if (isTypeAny(onfulfilledParameterType)) { + return undefined; + } + + const onfulfilledParameterSignatures = getSignaturesOfType(onfulfilledParameterType, SignatureKind.Call); + if (onfulfilledParameterSignatures.length === 0) { + if (errorNode) { + error(errorNode, Diagnostics.The_first_parameter_of_the_then_method_of_a_promise_must_be_a_callback); + } + return undefined; + } + + return typeAsPromise.promisedTypeOfPromise = getUnionType(map(onfulfilledParameterSignatures, getTypeOfFirstParameterOfSignature), UnionReduction.Subtype); + } + + /** + * Gets the "awaited type" of a type. + * @param type The type to await. + * @param withAlias When `true`, wraps the "awaited type" in `Awaited` if needed. + * @remarks The "awaited type" of an expression is its "promised type" if the expression is a + * Promise-like type; otherwise, it is the type of the expression. This is used to reflect + * The runtime behavior of the `await` keyword. + */ + function checkAwaitedType(type: Type, withAlias: boolean, errorNode: Node, diagnosticMessage: DiagnosticMessage, ...args: DiagnosticArguments): Type { + const awaitedType = withAlias ? + getAwaitedType(type, errorNode, diagnosticMessage, ...args) : + getAwaitedTypeNoAlias(type, errorNode, diagnosticMessage, ...args); + return awaitedType || errorType; + } + + /** + * Determines whether a type is an object with a callable `then` member. + */ + function isThenableType(type: Type): boolean { + if (allTypesAssignableToKind(getBaseConstraintOrType(type), TypeFlags.Primitive | TypeFlags.Never)) { + // primitive types cannot be considered "thenable" since they are not objects. + return false; + } + + const thenFunction = getTypeOfPropertyOfType(type, "then" as __String); + return !!thenFunction && getSignaturesOfType(getTypeWithFacts(thenFunction, TypeFacts.NEUndefinedOrNull), SignatureKind.Call).length > 0; + } + + interface AwaitedTypeInstantiation extends Type { + _awaitedTypeBrand: never; + aliasSymbol: Symbol; + aliasTypeArguments: readonly Type[]; + } + + function isAwaitedTypeInstantiation(type: Type): type is AwaitedTypeInstantiation { + if (type.flags & TypeFlags.Conditional) { + const awaitedSymbol = getGlobalAwaitedSymbol(/*reportErrors*/ false); + return !!awaitedSymbol && type.aliasSymbol === awaitedSymbol && type.aliasTypeArguments?.length === 1; + } + return false; + } + + /** + * For a generic `Awaited`, gets `T`. + */ + function unwrapAwaitedType(type: Type) { + return type.flags & TypeFlags.Union ? mapType(type, unwrapAwaitedType) : + isAwaitedTypeInstantiation(type) ? type.aliasTypeArguments[0] : + type; + } + + function isAwaitedTypeNeeded(type: Type) { + // If this is already an `Awaited`, we shouldn't wrap it. This helps to avoid `Awaited>` in higher-order. + if (isTypeAny(type) || isAwaitedTypeInstantiation(type)) { + return false; + } + + // We only need `Awaited` if `T` contains possibly non-primitive types. + if (isGenericObjectType(type)) { + const baseConstraint = getBaseConstraintOfType(type); + // We only need `Awaited` if `T` is a type variable that has no base constraint, or the base constraint of `T` is `any`, `unknown`, `{}`, `object`, + // or is promise-like. + if ( + baseConstraint ? + baseConstraint.flags & TypeFlags.AnyOrUnknown || isEmptyObjectType(baseConstraint) || someType(baseConstraint, isThenableType) : + maybeTypeOfKind(type, TypeFlags.TypeVariable) + ) { + return true; + } + } + + return false; + } + + function tryCreateAwaitedType(type: Type): Type | undefined { + // Nothing to do if `Awaited` doesn't exist + const awaitedSymbol = getGlobalAwaitedSymbol(/*reportErrors*/ true); + if (awaitedSymbol) { + // Unwrap unions that may contain `Awaited`, otherwise its possible to manufacture an `Awaited | U>` where + // an `Awaited` would suffice. + return getTypeAliasInstantiation(awaitedSymbol, [unwrapAwaitedType(type)]); + } + + return undefined; + } + + function createAwaitedTypeIfNeeded(type: Type): Type { + // We wrap type `T` in `Awaited` based on the following conditions: + // - `T` is not already an `Awaited`, and + // - `T` is generic, and + // - One of the following applies: + // - `T` has no base constraint, or + // - The base constraint of `T` is `any`, `unknown`, `object`, or `{}`, or + // - The base constraint of `T` is an object type with a callable `then` method. + + if (isAwaitedTypeNeeded(type)) { + return tryCreateAwaitedType(type) ?? type; + } + + Debug.assert(isAwaitedTypeInstantiation(type) || getPromisedTypeOfPromise(type) === undefined, "type provided should not be a non-generic 'promise'-like."); + return type; + } + + /** + * Gets the "awaited type" of a type. + * + * The "awaited type" of an expression is its "promised type" if the expression is a + * Promise-like type; otherwise, it is the type of the expression. If the "promised + * type" is itself a Promise-like, the "promised type" is recursively unwrapped until a + * non-promise type is found. + * + * This is used to reflect the runtime behavior of the `await` keyword. + */ + function getAwaitedType(type: Type, errorNode?: Node, diagnosticMessage?: DiagnosticMessage, ...args: DiagnosticArguments): Type | undefined { + const awaitedType = getAwaitedTypeNoAlias(type, errorNode, diagnosticMessage, ...args); + return awaitedType && createAwaitedTypeIfNeeded(awaitedType); + } + + /** + * Gets the "awaited type" of a type without introducing an `Awaited` wrapper. + * + * @see {@link getAwaitedType} + */ + function getAwaitedTypeNoAlias(type: Type, errorNode?: Node, diagnosticMessage?: DiagnosticMessage, ...args: DiagnosticArguments): Type | undefined { + if (isTypeAny(type)) { + return type; + } + + // If this is already an `Awaited`, just return it. This avoids `Awaited>` in higher-order + if (isAwaitedTypeInstantiation(type)) { + return type; + } + + // If we've already cached an awaited type, return a possible `Awaited` for it. + const typeAsAwaitable = type as PromiseOrAwaitableType; + if (typeAsAwaitable.awaitedTypeOfType) { + return typeAsAwaitable.awaitedTypeOfType; + } + + // For a union, get a union of the awaited types of each constituent. + if (type.flags & TypeFlags.Union) { + if (awaitedTypeStack.lastIndexOf(type.id) >= 0) { + if (errorNode) { + error(errorNode, Diagnostics.Type_is_referenced_directly_or_indirectly_in_the_fulfillment_callback_of_its_own_then_method); + } + return undefined; + } + + const mapper = errorNode ? (constituentType: Type) => getAwaitedTypeNoAlias(constituentType, errorNode, diagnosticMessage, ...args) : getAwaitedTypeNoAlias; + + awaitedTypeStack.push(type.id); + const mapped = mapType(type, mapper); + awaitedTypeStack.pop(); + + return typeAsAwaitable.awaitedTypeOfType = mapped; + } + + // If `type` is generic and should be wrapped in `Awaited`, return it. + if (isAwaitedTypeNeeded(type)) { + return typeAsAwaitable.awaitedTypeOfType = type; + } + + const thisTypeForErrorOut: { value: Type | undefined; } = { value: undefined }; + const promisedType = getPromisedTypeOfPromise(type, /*errorNode*/ undefined, thisTypeForErrorOut); + if (promisedType) { + if (type.id === promisedType.id || awaitedTypeStack.lastIndexOf(promisedType.id) >= 0) { + // Verify that we don't have a bad actor in the form of a promise whose + // promised type is the same as the promise type, or a mutually recursive + // promise. If so, we return undefined as we cannot guess the shape. If this + // were the actual case in the JavaScript, this Promise would never resolve. + // + // An example of a bad actor with a singly-recursive promise type might + // be: + // + // interface BadPromise { + // then( + // onfulfilled: (value: BadPromise) => any, + // onrejected: (error: any) => any): BadPromise; + // } + // + // The above interface will pass the PromiseLike check, and return a + // promised type of `BadPromise`. Since this is a self reference, we + // don't want to keep recursing ad infinitum. + // + // An example of a bad actor in the form of a mutually-recursive + // promise type might be: + // + // interface BadPromiseA { + // then( + // onfulfilled: (value: BadPromiseB) => any, + // onrejected: (error: any) => any): BadPromiseB; + // } + // + // interface BadPromiseB { + // then( + // onfulfilled: (value: BadPromiseA) => any, + // onrejected: (error: any) => any): BadPromiseA; + // } + // + if (errorNode) { + error(errorNode, Diagnostics.Type_is_referenced_directly_or_indirectly_in_the_fulfillment_callback_of_its_own_then_method); + } + return undefined; + } + + // Keep track of the type we're about to unwrap to avoid bad recursive promise types. + // See the comments above for more information. + awaitedTypeStack.push(type.id); + const awaitedType = getAwaitedTypeNoAlias(promisedType, errorNode, diagnosticMessage, ...args); + awaitedTypeStack.pop(); + + if (!awaitedType) { + return undefined; + } + + return typeAsAwaitable.awaitedTypeOfType = awaitedType; + } + + // The type was not a promise, so it could not be unwrapped any further. + // As long as the type does not have a callable "then" property, it is + // safe to return the type; otherwise, an error is reported and we return + // undefined. + // + // An example of a non-promise "thenable" might be: + // + // await { then(): void {} } + // + // The "thenable" does not match the minimal definition for a promise. When + // a Promise/A+-compatible or ES6 promise tries to adopt this value, the promise + // will never settle. We treat this as an error to help flag an early indicator + // of a runtime problem. If the user wants to return this value from an async + // function, they would need to wrap it in some other value. If they want it to + // be treated as a promise, they can cast to . + if (isThenableType(type)) { + if (errorNode) { + Debug.assertIsDefined(diagnosticMessage); + let chain: DiagnosticMessageChain | undefined; + if (thisTypeForErrorOut.value) { + chain = chainDiagnosticMessages(chain, Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1, typeToString(type), typeToString(thisTypeForErrorOut.value)); + } + chain = chainDiagnosticMessages(chain, diagnosticMessage, ...args); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorNode), errorNode, chain)); + } + return undefined; + } + + return typeAsAwaitable.awaitedTypeOfType = type; + } + + /** + * Checks the return type of an async function to ensure it is a compatible + * Promise implementation. + * + * This checks that an async function has a valid Promise-compatible return type. + * An async function has a valid Promise-compatible return type if the resolved value + * of the return type has a construct signature that takes in an `initializer` function + * that in turn supplies a `resolve` function as one of its arguments and results in an + * object with a callable `then` signature. + * + * @param node The signature to check + */ + function checkAsyncFunctionReturnType(node: FunctionLikeDeclaration | MethodSignature, returnTypeNode: TypeNode, returnTypeErrorLocation: TypeNode) { + // As part of our emit for an async function, we will need to emit the entity name of + // the return type annotation as an expression. To meet the necessary runtime semantics + // for __awaiter, we must also check that the type of the declaration (e.g. the static + // side or "constructor" of the promise type) is compatible `PromiseConstructorLike`. + // + // An example might be (from lib.es6.d.ts): + // + // interface Promise { ... } + // interface PromiseConstructor { + // new (...): Promise; + // } + // declare var Promise: PromiseConstructor; + // + // When an async function declares a return type annotation of `Promise`, we + // need to get the type of the `Promise` variable declaration above, which would + // be `PromiseConstructor`. + // + // The same case applies to a class: + // + // declare class Promise { + // constructor(...); + // then(...): Promise; + // } + // + const returnType = getTypeFromTypeNode(returnTypeNode); + if (languageVersion >= ScriptTarget.ES2015) { + if (isErrorType(returnType)) { + return; + } + const globalPromiseType = getGlobalPromiseType(/*reportErrors*/ true); + if (globalPromiseType !== emptyGenericType && !isReferenceToType(returnType, globalPromiseType)) { + // The promise type was not a valid type reference to the global promise type, so we + // report an error and return the unknown type. + reportErrorForInvalidReturnType(Diagnostics.The_return_type_of_an_async_function_or_method_must_be_the_global_Promise_T_type_Did_you_mean_to_write_Promise_0, returnTypeNode, returnTypeErrorLocation, typeToString(getAwaitedTypeNoAlias(returnType) || voidType)); + return; + } + } + else { + // Always mark the type node as referenced if it points to a value + markLinkedReferences(node, ReferenceHint.AsyncFunction); + if (isErrorType(returnType)) { + return; + } + + const promiseConstructorName = getEntityNameFromTypeNode(returnTypeNode); + if (promiseConstructorName === undefined) { + reportErrorForInvalidReturnType(Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_because_it_does_not_refer_to_a_Promise_compatible_constructor_value, returnTypeNode, returnTypeErrorLocation, typeToString(returnType)); + return; + } + + const promiseConstructorSymbol = resolveEntityName(promiseConstructorName, SymbolFlags.Value, /*ignoreErrors*/ true); + const promiseConstructorType = promiseConstructorSymbol ? getTypeOfSymbol(promiseConstructorSymbol) : errorType; + if (isErrorType(promiseConstructorType)) { + if (promiseConstructorName.kind === SyntaxKind.Identifier && promiseConstructorName.escapedText === "Promise" && getTargetType(returnType) === getGlobalPromiseType(/*reportErrors*/ false)) { + error(returnTypeErrorLocation, Diagnostics.An_async_function_or_method_in_ES5_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option); + } + else { + reportErrorForInvalidReturnType(Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_because_it_does_not_refer_to_a_Promise_compatible_constructor_value, returnTypeNode, returnTypeErrorLocation, entityNameToString(promiseConstructorName)); + } + return; + } + + const globalPromiseConstructorLikeType = getGlobalPromiseConstructorLikeType(/*reportErrors*/ true); + if (globalPromiseConstructorLikeType === emptyObjectType) { + // If we couldn't resolve the global PromiseConstructorLike type we cannot verify + // compatibility with __awaiter. + reportErrorForInvalidReturnType(Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_because_it_does_not_refer_to_a_Promise_compatible_constructor_value, returnTypeNode, returnTypeErrorLocation, entityNameToString(promiseConstructorName)); + return; + } + + const headMessage = Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_because_it_does_not_refer_to_a_Promise_compatible_constructor_value; + const errorInfo = () => returnTypeNode === returnTypeErrorLocation ? undefined : chainDiagnosticMessages(/*details*/ undefined, Diagnostics.The_return_type_of_an_async_function_or_method_must_be_the_global_Promise_T_type); + if (!checkTypeAssignableTo(promiseConstructorType, globalPromiseConstructorLikeType, returnTypeErrorLocation, headMessage, errorInfo)) { + return; + } + + // Verify there is no local declaration that could collide with the promise constructor. + const rootName = promiseConstructorName && getFirstIdentifier(promiseConstructorName); + const collidingSymbol = getSymbol(node.locals!, rootName.escapedText, SymbolFlags.Value); + if (collidingSymbol) { + error(collidingSymbol.valueDeclaration, Diagnostics.Duplicate_identifier_0_Compiler_uses_declaration_1_to_support_async_functions, idText(rootName), entityNameToString(promiseConstructorName)); + return; + } + } + + checkAwaitedType(returnType, /*withAlias*/ false, node, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); + + function reportErrorForInvalidReturnType(message: DiagnosticMessage, returnTypeNode: TypeNode, returnTypeErrorLocation: TypeNode, typeName: string) { + if (returnTypeNode === returnTypeErrorLocation) { + error(returnTypeErrorLocation, message, typeName); + } + else { + const diag = error(returnTypeErrorLocation, Diagnostics.The_return_type_of_an_async_function_or_method_must_be_the_global_Promise_T_type); + addRelatedInfo(diag, createDiagnosticForNode(returnTypeNode, message, typeName)); + } + } + } + + function checkGrammarDecorator(decorator: Decorator): boolean { + const sourceFile = getSourceFileOfNode(decorator); + if (!hasParseDiagnostics(sourceFile)) { + let node: Expression = decorator.expression; + + // DecoratorParenthesizedExpression : + // `(` Expression `)` + + if (isParenthesizedExpression(node)) { + return false; + } + + let canHaveCallExpression = true; + let errorNode: Node | undefined; + while (true) { + // Allow TS syntax such as non-null assertions and instantiation expressions + if (isExpressionWithTypeArguments(node) || isNonNullExpression(node)) { + node = node.expression; + continue; + } + + // DecoratorCallExpression : + // DecoratorMemberExpression Arguments + + if (isCallExpression(node)) { + if (!canHaveCallExpression) { + errorNode = node; + } + if (node.questionDotToken) { + // Even if we already have an error node, error at the `?.` token since it appears earlier. + errorNode = node.questionDotToken; + } + node = node.expression; + canHaveCallExpression = false; + continue; + } + + // DecoratorMemberExpression : + // IdentifierReference + // DecoratorMemberExpression `.` IdentifierName + // DecoratorMemberExpression `.` PrivateIdentifier + + if (isPropertyAccessExpression(node)) { + if (node.questionDotToken) { + // Even if we already have an error node, error at the `?.` token since it appears earlier. + errorNode = node.questionDotToken; + } + node = node.expression; + canHaveCallExpression = false; + continue; + } + + if (!isIdentifier(node)) { + // Even if we already have an error node, error at this node since it appears earlier. + errorNode = node; + } + + break; + } + + if (errorNode) { + addRelatedInfo( + error(decorator.expression, Diagnostics.Expression_must_be_enclosed_in_parentheses_to_be_used_as_a_decorator), + createDiagnosticForNode(errorNode, Diagnostics.Invalid_syntax_in_decorator), + ); + return true; + } + } + + return false; + } + + /** Check a decorator */ + function checkDecorator(node: Decorator): void { + checkGrammarDecorator(node); + + const signature = getResolvedSignature(node); + checkDeprecatedSignature(signature, node); + const returnType = getReturnTypeOfSignature(signature); + if (returnType.flags & TypeFlags.Any) { + return; + } + + // if we fail to get a signature and return type here, we will have already reported a grammar error in `checkDecorators`. + const decoratorSignature = getDecoratorCallSignature(node); + if (!decoratorSignature?.resolvedReturnType) return; + + let headMessage: DiagnosticMessage; + const expectedReturnType = decoratorSignature.resolvedReturnType; + switch (node.parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + headMessage = Diagnostics.Decorator_function_return_type_0_is_not_assignable_to_type_1; + break; + + case SyntaxKind.PropertyDeclaration: + if (!legacyDecorators) { + headMessage = Diagnostics.Decorator_function_return_type_0_is_not_assignable_to_type_1; + break; + } + // falls through + + case SyntaxKind.Parameter: + headMessage = Diagnostics.Decorator_function_return_type_is_0_but_is_expected_to_be_void_or_any; + break; + + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + headMessage = Diagnostics.Decorator_function_return_type_0_is_not_assignable_to_type_1; + break; + + default: + return Debug.failBadSyntaxKind(node.parent); + } + + checkTypeAssignableTo(returnType, expectedReturnType, node.expression, headMessage); + } + + /** + * Creates a synthetic `Signature` corresponding to a call signature. + */ + function createCallSignature( + typeParameters: readonly TypeParameter[] | undefined, + thisParameter: Symbol | undefined, + parameters: readonly Symbol[], + returnType: Type, + typePredicate?: TypePredicate, + minArgumentCount: number = parameters.length, + flags: SignatureFlags = SignatureFlags.None, + ) { + const decl = factory.createFunctionTypeNode(/*typeParameters*/ undefined, emptyArray, factory.createKeywordTypeNode(SyntaxKind.AnyKeyword)); + return createSignature(decl, typeParameters, thisParameter, parameters, returnType, typePredicate, minArgumentCount, flags); + } + + /** + * Creates a synthetic `FunctionType` + */ + function createFunctionType( + typeParameters: readonly TypeParameter[] | undefined, + thisParameter: Symbol | undefined, + parameters: readonly Symbol[], + returnType: Type, + typePredicate?: TypePredicate, + minArgumentCount?: number, + flags?: SignatureFlags, + ) { + const signature = createCallSignature(typeParameters, thisParameter, parameters, returnType, typePredicate, minArgumentCount, flags); + return getOrCreateTypeFromSignature(signature); + } + + function createGetterFunctionType(type: Type) { + return createFunctionType(/*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, type); + } + + function createSetterFunctionType(type: Type) { + const valueParam = createParameter("value" as __String, type); + return createFunctionType(/*typeParameters*/ undefined, /*thisParameter*/ undefined, [valueParam], voidType); + } + + function getEntityNameForDecoratorMetadata(node: TypeNode | undefined): EntityName | undefined { + if (node) { + switch (node.kind) { + case SyntaxKind.IntersectionType: + case SyntaxKind.UnionType: + return getEntityNameForDecoratorMetadataFromTypeList((node as UnionOrIntersectionTypeNode).types); + + case SyntaxKind.ConditionalType: + return getEntityNameForDecoratorMetadataFromTypeList([(node as ConditionalTypeNode).trueType, (node as ConditionalTypeNode).falseType]); + + case SyntaxKind.ParenthesizedType: + case SyntaxKind.NamedTupleMember: + return getEntityNameForDecoratorMetadata((node as ParenthesizedTypeNode).type); + + case SyntaxKind.TypeReference: + return (node as TypeReferenceNode).typeName; + } + } + } + + function getEntityNameForDecoratorMetadataFromTypeList(types: readonly TypeNode[]): EntityName | undefined { + let commonEntityName: EntityName | undefined; + for (let typeNode of types) { + while (typeNode.kind === SyntaxKind.ParenthesizedType || typeNode.kind === SyntaxKind.NamedTupleMember) { + typeNode = (typeNode as ParenthesizedTypeNode | NamedTupleMember).type; // Skip parens if need be + } + if (typeNode.kind === SyntaxKind.NeverKeyword) { + continue; // Always elide `never` from the union/intersection if possible + } + if (!strictNullChecks && (typeNode.kind === SyntaxKind.LiteralType && (typeNode as LiteralTypeNode).literal.kind === SyntaxKind.NullKeyword || typeNode.kind === SyntaxKind.UndefinedKeyword)) { + continue; // Elide null and undefined from unions for metadata, just like what we did prior to the implementation of strict null checks + } + const individualEntityName = getEntityNameForDecoratorMetadata(typeNode); + if (!individualEntityName) { + // Individual is something like string number + // So it would be serialized to either that type or object + // Safe to return here + return undefined; + } + + if (commonEntityName) { + // Note this is in sync with the transformation that happens for type node. + // Keep this in sync with serializeUnionOrIntersectionType + // Verify if they refer to same entity and is identifier + // return undefined if they dont match because we would emit object + if ( + !isIdentifier(commonEntityName) || + !isIdentifier(individualEntityName) || + commonEntityName.escapedText !== individualEntityName.escapedText + ) { + return undefined; + } + } + else { + commonEntityName = individualEntityName; + } + } + return commonEntityName; + } + + function getParameterTypeNodeForDecoratorCheck(node: ParameterDeclaration): TypeNode | undefined { + const typeNode = getEffectiveTypeAnnotationNode(node); + return isRestParameter(node) ? getRestParameterElementType(typeNode) : typeNode; + } + + /** Check the decorators of a node */ + function checkDecorators(node: Node): void { + // skip this check for nodes that cannot have decorators. These should have already had an error reported by + // checkGrammarModifiers. + if (!canHaveDecorators(node) || !hasDecorators(node) || !node.modifiers || !nodeCanBeDecorated(legacyDecorators, node, node.parent, node.parent.parent)) { + return; + } + + const firstDecorator = find(node.modifiers, isDecorator); + if (!firstDecorator) { + return; + } + + if (legacyDecorators) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Decorate); + if (node.kind === SyntaxKind.Parameter) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Param); + } + } + else if (languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.ESDecorateAndRunInitializers); + if (isClassDeclaration(node)) { + if (!node.name) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.SetFunctionName); + } + else { + const member = getFirstTransformableStaticClassElement(node); + if (member) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.SetFunctionName); + } + } + } + else if (!isClassExpression(node)) { + if (isPrivateIdentifier(node.name) && (isMethodDeclaration(node) || isAccessor(node) || isAutoAccessorPropertyDeclaration(node))) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.SetFunctionName); + } + if (isComputedPropertyName(node.name)) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.PropKey); + } + } + } + + markLinkedReferences(node, ReferenceHint.Decorator); + + for (const modifier of node.modifiers) { + if (isDecorator(modifier)) { + checkDecorator(modifier); + } + } + } + + function checkFunctionDeclaration(node: FunctionDeclaration): void { + addLazyDiagnostic(checkFunctionDeclarationDiagnostics); + + function checkFunctionDeclarationDiagnostics() { + checkFunctionOrMethodDeclaration(node); + checkGrammarForGenerator(node); + checkCollisionsForDeclarationName(node, node.name); + } + } + + function checkJSDocTypeAliasTag(node: JSDocTypedefTag | JSDocCallbackTag) { + if (!node.typeExpression) { + // If the node had `@property` tags, `typeExpression` would have been set to the first property tag. + error(node.name, Diagnostics.JSDoc_typedef_tag_should_either_have_a_type_annotation_or_be_followed_by_property_or_member_tags); + } + + if (node.name) { + checkTypeNameIsReserved(node.name, Diagnostics.Type_alias_name_cannot_be_0); + } + checkSourceElement(node.typeExpression); + checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); + } + + function checkJSDocTemplateTag(node: JSDocTemplateTag): void { + checkSourceElement(node.constraint); + for (const tp of node.typeParameters) { + checkSourceElement(tp); + } + } + + function checkJSDocTypeTag(node: JSDocTypeTag) { + checkSourceElement(node.typeExpression); + } + + function checkJSDocSatisfiesTag(node: JSDocSatisfiesTag) { + checkSourceElement(node.typeExpression); + const host = getEffectiveJSDocHost(node); + if (host) { + const tags = getAllJSDocTags(host, isJSDocSatisfiesTag); + if (length(tags) > 1) { + for (let i = 1; i < length(tags); i++) { + const tagName = tags[i].tagName; + error(tagName, Diagnostics._0_tag_already_specified, idText(tagName)); + } + } + } + } + + function checkJSDocLinkLikeTag(node: JSDocLink | JSDocLinkCode | JSDocLinkPlain) { + if (node.name) { + resolveJSDocMemberName(node.name, /*ignoreErrors*/ true); + } + } + + function checkJSDocParameterTag(node: JSDocParameterTag) { + checkSourceElement(node.typeExpression); + } + + function checkJSDocPropertyTag(node: JSDocPropertyTag) { + checkSourceElement(node.typeExpression); + } + + function checkJSDocFunctionType(node: JSDocFunctionType): void { + addLazyDiagnostic(checkJSDocFunctionTypeImplicitAny); + checkSignatureDeclaration(node); + + function checkJSDocFunctionTypeImplicitAny() { + if (!node.type && !isJSDocConstructSignature(node)) { + reportImplicitAny(node, anyType); + } + } + } + + function checkJSDocThisTag(node: JSDocThisTag) { + const host = getEffectiveJSDocHost(node); + if (host && isArrowFunction(host)) { + error(node.tagName, Diagnostics.An_arrow_function_cannot_have_a_this_parameter); + } + } + + function checkJSDocImportTag(node: JSDocImportTag) { + checkImportAttributes(node); + } + + function checkJSDocImplementsTag(node: JSDocImplementsTag): void { + const classLike = getEffectiveJSDocHost(node); + if (!classLike || !isClassDeclaration(classLike) && !isClassExpression(classLike)) { + error(classLike, Diagnostics.JSDoc_0_is_not_attached_to_a_class, idText(node.tagName)); + } + } + + function checkJSDocAugmentsTag(node: JSDocAugmentsTag): void { + const classLike = getEffectiveJSDocHost(node); + if (!classLike || !isClassDeclaration(classLike) && !isClassExpression(classLike)) { + error(classLike, Diagnostics.JSDoc_0_is_not_attached_to_a_class, idText(node.tagName)); + return; + } + + const augmentsTags = getJSDocTags(classLike).filter(isJSDocAugmentsTag); + Debug.assert(augmentsTags.length > 0); + if (augmentsTags.length > 1) { + error(augmentsTags[1], Diagnostics.Class_declarations_cannot_have_more_than_one_augments_or_extends_tag); + } + + const name = getIdentifierFromEntityNameExpression(node.class.expression); + const extend = getClassExtendsHeritageElement(classLike); + if (extend) { + const className = getIdentifierFromEntityNameExpression(extend.expression); + if (className && name.escapedText !== className.escapedText) { + error(name, Diagnostics.JSDoc_0_1_does_not_match_the_extends_2_clause, idText(node.tagName), idText(name), idText(className)); + } + } + } + + function checkJSDocAccessibilityModifiers(node: JSDocPublicTag | JSDocProtectedTag | JSDocPrivateTag): void { + const host = getJSDocHost(node); + if (host && isPrivateIdentifierClassElementDeclaration(host)) { + error(node, Diagnostics.An_accessibility_modifier_cannot_be_used_with_a_private_identifier); + } + } + + function getIdentifierFromEntityNameExpression(node: Identifier | PropertyAccessExpression): Identifier | PrivateIdentifier; + function getIdentifierFromEntityNameExpression(node: Expression): Identifier | PrivateIdentifier | undefined; + function getIdentifierFromEntityNameExpression(node: Expression): Identifier | PrivateIdentifier | undefined { + switch (node.kind) { + case SyntaxKind.Identifier: + return node as Identifier; + case SyntaxKind.PropertyAccessExpression: + return (node as PropertyAccessExpression).name; + default: + return undefined; + } + } + + function checkFunctionOrMethodDeclaration(node: FunctionDeclaration | MethodDeclaration | MethodSignature): void { + checkDecorators(node); + checkSignatureDeclaration(node); + const functionFlags = getFunctionFlags(node); + + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name && node.name.kind === SyntaxKind.ComputedPropertyName) { + // This check will account for methods in class/interface declarations, + // as well as accessors in classes/object literals + checkComputedPropertyName(node.name); + } + + if (hasBindableName(node)) { + // first we want to check the local symbol that contain this declaration + // - if node.localSymbol !== undefined - this is current declaration is exported and localSymbol points to the local symbol + // - if node.localSymbol === undefined - this node is non-exported so we can just pick the result of getSymbolOfNode + const symbol = getSymbolOfDeclaration(node); + const localSymbol = node.localSymbol || symbol; + + // Since the javascript won't do semantic analysis like typescript, + // if the javascript file comes before the typescript file and both contain same name functions, + // checkFunctionOrConstructorSymbol wouldn't be called if we didnt ignore javascript function. + const firstDeclaration = localSymbol.declarations?.find( + // Get first non javascript function declaration + declaration => declaration.kind === node.kind && !(declaration.flags & NodeFlags.JavaScriptFile), + ); + + // Only type check the symbol once + if (node === firstDeclaration) { + checkFunctionOrConstructorSymbol(localSymbol); + } + + if (symbol.parent) { + // run check on export symbol to check that modifiers agree across all exported declarations + checkFunctionOrConstructorSymbol(symbol); + } + } + + const body = node.kind === SyntaxKind.MethodSignature ? undefined : node.body; + checkSourceElement(body); + checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, getReturnTypeFromAnnotation(node)); + + addLazyDiagnostic(checkFunctionOrMethodDeclarationDiagnostics); + + // A js function declaration can have a @type tag instead of a return type node, but that type must have a call signature + if (isInJSFile(node)) { + const typeTag = getJSDocTypeTag(node); + if (typeTag && typeTag.typeExpression && !getContextualCallSignature(getTypeFromTypeNode(typeTag.typeExpression), node)) { + error(typeTag.typeExpression.type, Diagnostics.The_type_of_a_function_declaration_must_match_the_function_s_signature); + } + } + + function checkFunctionOrMethodDeclarationDiagnostics() { + if (!getEffectiveReturnTypeNode(node)) { + // Report an implicit any error if there is no body, no explicit return type, and node is not a private method + // in an ambient context + if (nodeIsMissing(body) && !isPrivateWithinAmbient(node)) { + reportImplicitAny(node, anyType); + } + + if (functionFlags & FunctionFlags.Generator && nodeIsPresent(body)) { + // A generator with a body and no type annotation can still cause errors. It can error if the + // yielded values have no common supertype, or it can give an implicit any error if it has no + // yielded values. The only way to trigger these errors is to try checking its return type. + getReturnTypeOfSignature(getSignatureFromDeclaration(node)); + } + } + } + } + + function registerForUnusedIdentifiersCheck(node: PotentiallyUnusedIdentifier): void { + addLazyDiagnostic(registerForUnusedIdentifiersCheckDiagnostics); + + function registerForUnusedIdentifiersCheckDiagnostics() { + // May be in a call such as getTypeOfNode that happened to call this. But potentiallyUnusedIdentifiers is only defined in the scope of `checkSourceFile`. + const sourceFile = getSourceFileOfNode(node); + let potentiallyUnusedIdentifiers = allPotentiallyUnusedIdentifiers.get(sourceFile.path); + if (!potentiallyUnusedIdentifiers) { + potentiallyUnusedIdentifiers = []; + allPotentiallyUnusedIdentifiers.set(sourceFile.path, potentiallyUnusedIdentifiers); + } + // TODO: GH#22580 + // Debug.assert(addToSeen(seenPotentiallyUnusedIdentifiers, getNodeId(node)), "Adding potentially-unused identifier twice"); + potentiallyUnusedIdentifiers.push(node); + } + } + + type PotentiallyUnusedIdentifier = SourceFile | ModuleDeclaration | ClassLikeDeclaration | InterfaceDeclaration | Block | CaseBlock | ForStatement | ForInStatement | ForOfStatement | Exclude | TypeAliasDeclaration | InferTypeNode; + + function checkUnusedIdentifiers(potentiallyUnusedIdentifiers: readonly PotentiallyUnusedIdentifier[], addDiagnostic: AddUnusedDiagnostic) { + for (const node of potentiallyUnusedIdentifiers) { + switch (node.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + checkUnusedClassMembers(node, addDiagnostic); + checkUnusedTypeParameters(node, addDiagnostic); + break; + case SyntaxKind.SourceFile: + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.Block: + case SyntaxKind.CaseBlock: + case SyntaxKind.ForStatement: + case SyntaxKind.ForInStatement: + case SyntaxKind.ForOfStatement: + checkUnusedLocalsAndParameters(node, addDiagnostic); + break; + case SyntaxKind.Constructor: + case SyntaxKind.FunctionExpression: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + if (node.body) { // Don't report unused parameters in overloads + checkUnusedLocalsAndParameters(node, addDiagnostic); + } + checkUnusedTypeParameters(node, addDiagnostic); + break; + case SyntaxKind.MethodSignature: + case SyntaxKind.CallSignature: + case SyntaxKind.ConstructSignature: + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.InterfaceDeclaration: + checkUnusedTypeParameters(node, addDiagnostic); + break; + case SyntaxKind.InferType: + checkUnusedInferTypeParameter(node, addDiagnostic); + break; + default: + Debug.assertNever(node, "Node should not have been registered for unused identifiers check"); + } + } + } + + function errorUnusedLocal(declaration: Declaration, name: string, addDiagnostic: AddUnusedDiagnostic) { + const node = getNameOfDeclaration(declaration) || declaration; + const message = isTypeDeclaration(declaration) ? Diagnostics._0_is_declared_but_never_used : Diagnostics._0_is_declared_but_its_value_is_never_read; + addDiagnostic(declaration, UnusedKind.Local, createDiagnosticForNode(node, message, name)); + } + + function isIdentifierThatStartsWithUnderscore(node: Node) { + return isIdentifier(node) && idText(node).charCodeAt(0) === CharacterCodes._; + } + + function checkUnusedClassMembers(node: ClassDeclaration | ClassExpression, addDiagnostic: AddUnusedDiagnostic): void { + for (const member of node.members) { + switch (member.kind) { + case SyntaxKind.MethodDeclaration: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + if (member.kind === SyntaxKind.SetAccessor && member.symbol.flags & SymbolFlags.GetAccessor) { + // Already would have reported an error on the getter. + break; + } + const symbol = getSymbolOfDeclaration(member); + if ( + !symbol.isReferenced + && (hasEffectiveModifier(member, ModifierFlags.Private) || isNamedDeclaration(member) && isPrivateIdentifier(member.name)) + && !(member.flags & NodeFlags.Ambient) + ) { + addDiagnostic(member, UnusedKind.Local, createDiagnosticForNode(member.name!, Diagnostics._0_is_declared_but_its_value_is_never_read, symbolToString(symbol))); + } + break; + case SyntaxKind.Constructor: + for (const parameter of (member as ConstructorDeclaration).parameters) { + if (!parameter.symbol.isReferenced && hasSyntacticModifier(parameter, ModifierFlags.Private)) { + addDiagnostic(parameter, UnusedKind.Local, createDiagnosticForNode(parameter.name, Diagnostics.Property_0_is_declared_but_its_value_is_never_read, symbolName(parameter.symbol))); + } + } + break; + case SyntaxKind.IndexSignature: + case SyntaxKind.SemicolonClassElement: + case SyntaxKind.ClassStaticBlockDeclaration: + // Can't be private + break; + default: + Debug.fail("Unexpected class member"); + } + } + } + + function checkUnusedInferTypeParameter(node: InferTypeNode, addDiagnostic: AddUnusedDiagnostic): void { + const { typeParameter } = node; + if (isTypeParameterUnused(typeParameter)) { + addDiagnostic(node, UnusedKind.Parameter, createDiagnosticForNode(node, Diagnostics._0_is_declared_but_its_value_is_never_read, idText(typeParameter.name))); + } + } + + function checkUnusedTypeParameters(node: ClassLikeDeclaration | SignatureDeclaration | InterfaceDeclaration | TypeAliasDeclaration, addDiagnostic: AddUnusedDiagnostic): void { + // Only report errors on the last declaration for the type parameter container; + // this ensures that all uses have been accounted for. + const declarations = getSymbolOfDeclaration(node).declarations; + if (!declarations || last(declarations) !== node) return; + + const typeParameters = getEffectiveTypeParameterDeclarations(node); + const seenParentsWithEveryUnused = new Set(); + + for (const typeParameter of typeParameters) { + if (!isTypeParameterUnused(typeParameter)) continue; + + const name = idText(typeParameter.name); + const { parent } = typeParameter; + if (parent.kind !== SyntaxKind.InferType && parent.typeParameters!.every(isTypeParameterUnused)) { + if (tryAddToSet(seenParentsWithEveryUnused, parent)) { + const sourceFile = getSourceFileOfNode(parent); + const range = isJSDocTemplateTag(parent) + // Whole @template tag + ? rangeOfNode(parent) + // Include the `<>` in the error message + : rangeOfTypeParameters(sourceFile, parent.typeParameters!); + const only = parent.typeParameters!.length === 1; + // TODO: following line is possible reason for bug #41974, unusedTypeParameters_TemplateTag + const messageAndArg: DiagnosticAndArguments = only + ? [Diagnostics._0_is_declared_but_its_value_is_never_read, name] + : [Diagnostics.All_type_parameters_are_unused]; + addDiagnostic(typeParameter, UnusedKind.Parameter, createFileDiagnostic(sourceFile, range.pos, range.end - range.pos, ...messageAndArg)); + } + } + else { + // TODO: following line is possible reason for bug #41974, unusedTypeParameters_TemplateTag + addDiagnostic(typeParameter, UnusedKind.Parameter, createDiagnosticForNode(typeParameter, Diagnostics._0_is_declared_but_its_value_is_never_read, name)); + } + } + } + function isTypeParameterUnused(typeParameter: TypeParameterDeclaration): boolean { + return !(getMergedSymbol(typeParameter.symbol).isReferenced! & SymbolFlags.TypeParameter) && !isIdentifierThatStartsWithUnderscore(typeParameter.name); + } + + function addToGroup(map: Map, key: K, value: V, getKey: (key: K) => number | string): void { + const keyString = String(getKey(key)); + const group = map.get(keyString); + if (group) { + group[1].push(value); + } + else { + map.set(keyString, [key, [value]]); + } + } + + function tryGetRootParameterDeclaration(node: Node): ParameterDeclaration | undefined { + return tryCast(getRootDeclaration(node), isParameter); + } + + function isValidUnusedLocalDeclaration(declaration: Declaration): boolean { + if (isBindingElement(declaration)) { + if (isObjectBindingPattern(declaration.parent)) { + /** + * ignore starts with underscore names _ + * const { a: _a } = { a: 1 } + */ + return !!(declaration.propertyName && isIdentifierThatStartsWithUnderscore(declaration.name)); + } + return isIdentifierThatStartsWithUnderscore(declaration.name); + } + return isAmbientModule(declaration) || + (isVariableDeclaration(declaration) && isForInOrOfStatement(declaration.parent.parent) || isImportedDeclaration(declaration)) && isIdentifierThatStartsWithUnderscore(declaration.name!); + } + + function checkUnusedLocalsAndParameters(nodeWithLocals: HasLocals, addDiagnostic: AddUnusedDiagnostic): void { + // Ideally we could use the ImportClause directly as a key, but must wait until we have full ES6 maps. So must store key along with value. + const unusedImports = new Map(); + const unusedDestructures = new Map(); + const unusedVariables = new Map(); + nodeWithLocals.locals!.forEach(local => { + // If it's purely a type parameter, ignore, will be checked in `checkUnusedTypeParameters`. + // If it's a type parameter merged with a parameter, check if the parameter-side is used. + if (local.flags & SymbolFlags.TypeParameter ? !(local.flags & SymbolFlags.Variable && !(local.isReferenced! & SymbolFlags.Variable)) : local.isReferenced || local.exportSymbol) { + return; + } + + if (local.declarations) { + for (const declaration of local.declarations) { + if (isValidUnusedLocalDeclaration(declaration)) { + continue; + } + + if (isImportedDeclaration(declaration)) { + addToGroup(unusedImports, importClauseFromImported(declaration), declaration, getNodeId); + } + else if (isBindingElement(declaration) && isObjectBindingPattern(declaration.parent)) { + // In `{ a, ...b }, `a` is considered used since it removes a property from `b`. `b` may still be unused though. + const lastElement = last(declaration.parent.elements); + if (declaration === lastElement || !last(declaration.parent.elements).dotDotDotToken) { + addToGroup(unusedDestructures, declaration.parent, declaration, getNodeId); + } + } + else if (isVariableDeclaration(declaration)) { + const blockScopeKind = getCombinedNodeFlagsCached(declaration) & NodeFlags.BlockScoped; + const name = getNameOfDeclaration(declaration); + if (blockScopeKind !== NodeFlags.Using && blockScopeKind !== NodeFlags.AwaitUsing || !name || !isIdentifierThatStartsWithUnderscore(name)) { + addToGroup(unusedVariables, declaration.parent, declaration, getNodeId); + } + } + else { + const parameter = local.valueDeclaration && tryGetRootParameterDeclaration(local.valueDeclaration); + const name = local.valueDeclaration && getNameOfDeclaration(local.valueDeclaration); + if (parameter && name) { + if (!isParameterPropertyDeclaration(parameter, parameter.parent) && !parameterIsThisKeyword(parameter) && !isIdentifierThatStartsWithUnderscore(name)) { + if (isBindingElement(declaration) && isArrayBindingPattern(declaration.parent)) { + addToGroup(unusedDestructures, declaration.parent, declaration, getNodeId); + } + else { + addDiagnostic(parameter, UnusedKind.Parameter, createDiagnosticForNode(name, Diagnostics._0_is_declared_but_its_value_is_never_read, symbolName(local))); + } + } + } + else { + errorUnusedLocal(declaration, symbolName(local), addDiagnostic); + } + } + } + } + }); + unusedImports.forEach(([importClause, unuseds]) => { + const importDecl = importClause.parent; + const nDeclarations = (importClause.name ? 1 : 0) + + (importClause.namedBindings ? + (importClause.namedBindings.kind === SyntaxKind.NamespaceImport ? 1 : importClause.namedBindings.elements.length) + : 0); + if (nDeclarations === unuseds.length) { + addDiagnostic( + importDecl, + UnusedKind.Local, + unuseds.length === 1 + ? createDiagnosticForNode(importDecl, Diagnostics._0_is_declared_but_its_value_is_never_read, idText(first(unuseds).name!)) + : createDiagnosticForNode(importDecl, Diagnostics.All_imports_in_import_declaration_are_unused), + ); + } + else { + for (const unused of unuseds) errorUnusedLocal(unused, idText(unused.name!), addDiagnostic); + } + }); + unusedDestructures.forEach(([bindingPattern, bindingElements]) => { + const kind = tryGetRootParameterDeclaration(bindingPattern.parent) ? UnusedKind.Parameter : UnusedKind.Local; + if (bindingPattern.elements.length === bindingElements.length) { + if (bindingElements.length === 1 && bindingPattern.parent.kind === SyntaxKind.VariableDeclaration && bindingPattern.parent.parent.kind === SyntaxKind.VariableDeclarationList) { + addToGroup(unusedVariables, bindingPattern.parent.parent, bindingPattern.parent, getNodeId); + } + else { + addDiagnostic( + bindingPattern, + kind, + bindingElements.length === 1 + ? createDiagnosticForNode(bindingPattern, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(first(bindingElements).name)) + : createDiagnosticForNode(bindingPattern, Diagnostics.All_destructured_elements_are_unused), + ); + } + } + else { + for (const e of bindingElements) { + addDiagnostic(e, kind, createDiagnosticForNode(e, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(e.name))); + } + } + }); + unusedVariables.forEach(([declarationList, declarations]) => { + if (declarationList.declarations.length === declarations.length) { + addDiagnostic( + declarationList, + UnusedKind.Local, + declarations.length === 1 + ? createDiagnosticForNode(first(declarations).name, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(first(declarations).name)) + : createDiagnosticForNode(declarationList.parent.kind === SyntaxKind.VariableStatement ? declarationList.parent : declarationList, Diagnostics.All_variables_are_unused), + ); + } + else { + for (const decl of declarations) { + addDiagnostic(decl, UnusedKind.Local, createDiagnosticForNode(decl, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(decl.name))); + } + } + }); + } + + function checkPotentialUncheckedRenamedBindingElementsInTypes() { + for (const node of potentialUnusedRenamedBindingElementsInTypes) { + if (!getSymbolOfDeclaration(node)?.isReferenced) { + const wrappingDeclaration = walkUpBindingElementsAndPatterns(node); + Debug.assert(isPartOfParameterDeclaration(wrappingDeclaration), "Only parameter declaration should be checked here"); + const diagnostic = createDiagnosticForNode(node.name, Diagnostics._0_is_an_unused_renaming_of_1_Did_you_intend_to_use_it_as_a_type_annotation, declarationNameToString(node.name), declarationNameToString(node.propertyName)); + if (!wrappingDeclaration.type) { + // entire parameter does not have type annotation, suggest adding an annotation + addRelatedInfo( + diagnostic, + createFileDiagnostic(getSourceFileOfNode(wrappingDeclaration), wrappingDeclaration.end, 1, Diagnostics.We_can_only_write_a_type_for_0_by_adding_a_type_for_the_entire_parameter_here, declarationNameToString(node.propertyName)), + ); + } + diagnostics.add(diagnostic); + } + } + } + + function bindingNameText(name: BindingName): string { + switch (name.kind) { + case SyntaxKind.Identifier: + return idText(name); + case SyntaxKind.ArrayBindingPattern: + case SyntaxKind.ObjectBindingPattern: + return bindingNameText(cast(first(name.elements), isBindingElement).name); + default: + return Debug.assertNever(name); + } + } + + type ImportedDeclaration = ImportClause | ImportSpecifier | NamespaceImport; + function isImportedDeclaration(node: Node): node is ImportedDeclaration { + return node.kind === SyntaxKind.ImportClause || node.kind === SyntaxKind.ImportSpecifier || node.kind === SyntaxKind.NamespaceImport; + } + function importClauseFromImported(decl: ImportedDeclaration): ImportClause { + return decl.kind === SyntaxKind.ImportClause ? decl : decl.kind === SyntaxKind.NamespaceImport ? decl.parent : decl.parent.parent; + } + + function checkBlock(node: Block) { + // Grammar checking for SyntaxKind.Block + if (node.kind === SyntaxKind.Block) { + checkGrammarStatementInAmbientContext(node); + } + if (isFunctionOrModuleBlock(node)) { + const saveFlowAnalysisDisabled = flowAnalysisDisabled; + forEach(node.statements, checkSourceElement); + flowAnalysisDisabled = saveFlowAnalysisDisabled; + } + else { + forEach(node.statements, checkSourceElement); + } + if (node.locals) { + registerForUnusedIdentifiersCheck(node); + } + } + + function checkCollisionWithArgumentsInGeneratedCode(node: SignatureDeclaration) { + // no rest parameters \ declaration context \ overload - no codegen impact + if (languageVersion >= ScriptTarget.ES2015 || !hasRestParameter(node) || node.flags & NodeFlags.Ambient || nodeIsMissing((node as FunctionLikeDeclaration).body)) { + return; + } + + forEach(node.parameters, p => { + if (p.name && !isBindingPattern(p.name) && p.name.escapedText === argumentsSymbol.escapedName) { + errorSkippedOn("noEmit", p, Diagnostics.Duplicate_identifier_arguments_Compiler_uses_arguments_to_initialize_rest_parameters); + } + }); + } + + /** + * Checks whether an {@link Identifier}, in the context of another {@link Node}, would collide with a runtime value + * of {@link name} in an outer scope. This is used to check for collisions for downlevel transformations that + * require names like `Object`, `Promise`, `Reflect`, `require`, `exports`, etc. + */ + function needCollisionCheckForIdentifier(node: Node, identifier: Identifier | undefined, name: string): boolean { + if (identifier?.escapedText !== name) { + return false; + } + + if ( + node.kind === SyntaxKind.PropertyDeclaration || + node.kind === SyntaxKind.PropertySignature || + node.kind === SyntaxKind.MethodDeclaration || + node.kind === SyntaxKind.MethodSignature || + node.kind === SyntaxKind.GetAccessor || + node.kind === SyntaxKind.SetAccessor || + node.kind === SyntaxKind.PropertyAssignment + ) { + // it is ok to have member named '_super', '_this', `Promise`, etc. - member access is always qualified + return false; + } + + if (node.flags & NodeFlags.Ambient) { + // ambient context - no codegen impact + return false; + } + + if (isImportClause(node) || isImportEqualsDeclaration(node) || isImportSpecifier(node)) { + // type-only imports do not require collision checks against runtime values. + if (isTypeOnlyImportOrExportDeclaration(node)) { + return false; + } + } + + const root = getRootDeclaration(node); + if (isParameter(root) && nodeIsMissing((root.parent as FunctionLikeDeclaration).body)) { + // just an overload - no codegen impact + return false; + } + + return true; + } + + // this function will run after checking the source file so 'CaptureThis' is correct for all nodes + function checkIfThisIsCapturedInEnclosingScope(node: Node): void { + findAncestor(node, current => { + if (getNodeCheckFlags(current) & NodeCheckFlags.CaptureThis) { + const isDeclaration = node.kind !== SyntaxKind.Identifier; + if (isDeclaration) { + error(getNameOfDeclaration(node as Declaration), Diagnostics.Duplicate_identifier_this_Compiler_uses_variable_declaration_this_to_capture_this_reference); + } + else { + error(node, Diagnostics.Expression_resolves_to_variable_declaration_this_that_compiler_uses_to_capture_this_reference); + } + return true; + } + return false; + }); + } + + function checkIfNewTargetIsCapturedInEnclosingScope(node: Node): void { + findAncestor(node, current => { + if (getNodeCheckFlags(current) & NodeCheckFlags.CaptureNewTarget) { + const isDeclaration = node.kind !== SyntaxKind.Identifier; + if (isDeclaration) { + error(getNameOfDeclaration(node as Declaration), Diagnostics.Duplicate_identifier_newTarget_Compiler_uses_variable_declaration_newTarget_to_capture_new_target_meta_property_reference); + } + else { + error(node, Diagnostics.Expression_resolves_to_variable_declaration_newTarget_that_compiler_uses_to_capture_new_target_meta_property_reference); + } + return true; + } + return false; + }); + } + + function checkCollisionWithRequireExportsInGeneratedCode(node: Node, name: Identifier | undefined) { + // No need to check for require or exports for ES6 modules and later + if (moduleKind >= ModuleKind.ES2015 && !(moduleKind >= ModuleKind.Node16 && getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS)) { + return; + } + + if (!name || !needCollisionCheckForIdentifier(node, name, "require") && !needCollisionCheckForIdentifier(node, name, "exports")) { + return; + } + + // Uninstantiated modules shouldnt do this check + if (isModuleDeclaration(node) && getModuleInstanceState(node) !== ModuleInstanceState.Instantiated) { + return; + } + + // In case of variable declaration, node.parent is variable statement so look at the variable statement's parent + const parent = getDeclarationContainer(node); + if (parent.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(parent as SourceFile)) { + // If the declaration happens to be in external module, report error that require and exports are reserved keywords + errorSkippedOn("noEmit", name, Diagnostics.Duplicate_identifier_0_Compiler_reserves_name_1_in_top_level_scope_of_a_module, declarationNameToString(name), declarationNameToString(name)); + } + } + + function checkCollisionWithGlobalPromiseInGeneratedCode(node: Node, name: Identifier | undefined): void { + if (!name || languageVersion >= ScriptTarget.ES2017 || !needCollisionCheckForIdentifier(node, name, "Promise")) { + return; + } + + // Uninstantiated modules shouldnt do this check + if (isModuleDeclaration(node) && getModuleInstanceState(node) !== ModuleInstanceState.Instantiated) { + return; + } + + // In case of variable declaration, node.parent is variable statement so look at the variable statement's parent + const parent = getDeclarationContainer(node); + if (parent.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(parent as SourceFile) && parent.flags & NodeFlags.HasAsyncFunctions) { + // If the declaration happens to be in external module, report error that Promise is a reserved identifier. + errorSkippedOn("noEmit", name, Diagnostics.Duplicate_identifier_0_Compiler_reserves_name_1_in_top_level_scope_of_a_module_containing_async_functions, declarationNameToString(name), declarationNameToString(name)); + } + } + + function recordPotentialCollisionWithWeakMapSetInGeneratedCode(node: Node, name: Identifier): void { + if ( + languageVersion <= ScriptTarget.ES2021 + && (needCollisionCheckForIdentifier(node, name, "WeakMap") || needCollisionCheckForIdentifier(node, name, "WeakSet")) + ) { + potentialWeakMapSetCollisions.push(node); + } + } + + function checkWeakMapSetCollision(node: Node) { + const enclosingBlockScope = getEnclosingBlockScopeContainer(node); + if (getNodeCheckFlags(enclosingBlockScope) & NodeCheckFlags.ContainsClassWithPrivateIdentifiers) { + Debug.assert(isNamedDeclaration(node) && isIdentifier(node.name) && typeof node.name.escapedText === "string", "The target of a WeakMap/WeakSet collision check should be an identifier"); + errorSkippedOn("noEmit", node, Diagnostics.Compiler_reserves_name_0_when_emitting_private_identifier_downlevel, node.name.escapedText); + } + } + + function recordPotentialCollisionWithReflectInGeneratedCode(node: Node, name: Identifier | undefined): void { + if ( + name && languageVersion >= ScriptTarget.ES2015 && languageVersion <= ScriptTarget.ES2021 + && needCollisionCheckForIdentifier(node, name, "Reflect") + ) { + potentialReflectCollisions.push(node); + } + } + + function checkReflectCollision(node: Node) { + let hasCollision = false; + if (isClassExpression(node)) { + // ClassExpression names don't contribute to their containers, but do matter for any of their block-scoped members. + for (const member of node.members) { + if (getNodeCheckFlags(member) & NodeCheckFlags.ContainsSuperPropertyInStaticInitializer) { + hasCollision = true; + break; + } + } + } + else if (isFunctionExpression(node)) { + // FunctionExpression names don't contribute to their containers, but do matter for their contents + if (getNodeCheckFlags(node) & NodeCheckFlags.ContainsSuperPropertyInStaticInitializer) { + hasCollision = true; + } + } + else { + const container = getEnclosingBlockScopeContainer(node); + if (container && getNodeCheckFlags(container) & NodeCheckFlags.ContainsSuperPropertyInStaticInitializer) { + hasCollision = true; + } + } + if (hasCollision) { + Debug.assert(isNamedDeclaration(node) && isIdentifier(node.name), "The target of a Reflect collision check should be an identifier"); + errorSkippedOn("noEmit", node, Diagnostics.Duplicate_identifier_0_Compiler_reserves_name_1_when_emitting_super_references_in_static_initializers, declarationNameToString(node.name), "Reflect"); + } + } + + function checkCollisionsForDeclarationName(node: Node, name: Identifier | undefined) { + if (!name) return; + checkCollisionWithRequireExportsInGeneratedCode(node, name); + checkCollisionWithGlobalPromiseInGeneratedCode(node, name); + recordPotentialCollisionWithWeakMapSetInGeneratedCode(node, name); + recordPotentialCollisionWithReflectInGeneratedCode(node, name); + if (isClassLike(node)) { + checkTypeNameIsReserved(name, Diagnostics.Class_name_cannot_be_0); + if (!(node.flags & NodeFlags.Ambient)) { + checkClassNameCollisionWithObject(name); + } + } + else if (isEnumDeclaration(node)) { + checkTypeNameIsReserved(name, Diagnostics.Enum_name_cannot_be_0); + } + } + + function checkVarDeclaredNamesNotShadowed(node: VariableDeclaration | BindingElement) { + // - ScriptBody : StatementList + // It is a Syntax Error if any element of the LexicallyDeclaredNames of StatementList + // also occurs in the VarDeclaredNames of StatementList. + + // - Block : { StatementList } + // It is a Syntax Error if any element of the LexicallyDeclaredNames of StatementList + // also occurs in the VarDeclaredNames of StatementList. + + // Variable declarations are hoisted to the top of their function scope. They can shadow + // block scoped declarations, which bind tighter. this will not be flagged as duplicate definition + // by the binder as the declaration scope is different. + // A non-initialized declaration is a no-op as the block declaration will resolve before the var + // declaration. the problem is if the declaration has an initializer. this will act as a write to the + // block declared value. this is fine for let, but not const. + // Only consider declarations with initializers, uninitialized const declarations will not + // step on a let/const variable. + // Do not consider const and const declarations, as duplicate block-scoped declarations + // are handled by the binder. + // We are only looking for const declarations that step on let\const declarations from a + // different scope. e.g.: + // { + // const x = 0; // localDeclarationSymbol obtained after name resolution will correspond to this declaration + // const x = 0; // symbol for this declaration will be 'symbol' + // } + + // skip block-scoped variables and parameters + if ((getCombinedNodeFlagsCached(node) & NodeFlags.BlockScoped) !== 0 || isPartOfParameterDeclaration(node)) { + return; + } + + // NOTE: in ES6 spec initializer is required in variable declarations where name is binding pattern + // so we'll always treat binding elements as initialized + + const symbol = getSymbolOfDeclaration(node); + if (symbol.flags & SymbolFlags.FunctionScopedVariable) { + if (!isIdentifier(node.name)) return Debug.fail(); + const localDeclarationSymbol = resolveName(node, node.name.escapedText, SymbolFlags.Variable, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if ( + localDeclarationSymbol && + localDeclarationSymbol !== symbol && + localDeclarationSymbol.flags & SymbolFlags.BlockScopedVariable + ) { + if (getDeclarationNodeFlagsFromSymbol(localDeclarationSymbol) & NodeFlags.BlockScoped) { + const varDeclList = getAncestor(localDeclarationSymbol.valueDeclaration, SyntaxKind.VariableDeclarationList)!; + const container = varDeclList.parent.kind === SyntaxKind.VariableStatement && varDeclList.parent.parent + ? varDeclList.parent.parent + : undefined; + + // names of block-scoped and function scoped variables can collide only + // if block scoped variable is defined in the function\module\source file scope (because of variable hoisting) + const namesShareScope = container && + (container.kind === SyntaxKind.Block && isFunctionLike(container.parent) || + container.kind === SyntaxKind.ModuleBlock || + container.kind === SyntaxKind.ModuleDeclaration || + container.kind === SyntaxKind.SourceFile); + + // here we know that function scoped variable is "shadowed" by block scoped one + // a var declatation can't hoist past a lexical declaration and it results in a SyntaxError at runtime + if (!namesShareScope) { + const name = symbolToString(localDeclarationSymbol); + error(node, Diagnostics.Cannot_initialize_outer_scoped_variable_0_in_the_same_scope_as_block_scoped_declaration_1, name, name); + } + } + } + } + } + + function convertAutoToAny(type: Type) { + return type === autoType ? anyType : type === autoArrayType ? anyArrayType : type; + } + + // Check variable, parameter, or property declaration + function checkVariableLikeDeclaration(node: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement) { + checkDecorators(node); + if (!isBindingElement(node)) { + checkSourceElement(node.type); + } + + // JSDoc `function(string, string): string` syntax results in parameters with no name + if (!node.name) { + return; + } + + // For a computed property, just check the initializer and exit + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + if (hasOnlyExpressionInitializer(node) && node.initializer) { + checkExpressionCached(node.initializer); + } + } + + if (isBindingElement(node)) { + if ( + node.propertyName && + isIdentifier(node.name) && + isPartOfParameterDeclaration(node) && + nodeIsMissing((getContainingFunction(node) as FunctionLikeDeclaration).body) + ) { + // type F = ({a: string}) => void; + // ^^^^^^ + // variable renaming in function type notation is confusing, + // so we forbid it even if noUnusedLocals is not enabled + potentialUnusedRenamedBindingElementsInTypes.push(node); + return; + } + + if (isObjectBindingPattern(node.parent) && node.dotDotDotToken && languageVersion < LanguageFeatureMinimumTarget.ObjectSpreadRest) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Rest); + } + // check computed properties inside property names of binding elements + if (node.propertyName && node.propertyName.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.propertyName); + } + + // check private/protected variable access + const parent = node.parent.parent; + const parentCheckMode = node.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal; + const parentType = getTypeForBindingElementParent(parent, parentCheckMode); + const name = node.propertyName || node.name; + if (parentType && !isBindingPattern(name)) { + const exprType = getLiteralTypeFromPropertyName(name); + if (isTypeUsableAsPropertyName(exprType)) { + const nameText = getPropertyNameFromType(exprType); + const property = getPropertyOfType(parentType, nameText); + if (property) { + markPropertyAsReferenced(property, /*nodeForCheckWriteOnly*/ undefined, /*isSelfTypeAccess*/ false); // A destructuring is never a write-only reference. + checkPropertyAccessibility(node, !!parent.initializer && parent.initializer.kind === SyntaxKind.SuperKeyword, /*writing*/ false, parentType, property); + } + } + } + } + + // For a binding pattern, check contained binding elements + if (isBindingPattern(node.name)) { + if (node.name.kind === SyntaxKind.ArrayBindingPattern && languageVersion < LanguageFeatureMinimumTarget.BindingPatterns && compilerOptions.downlevelIteration) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Read); + } + + forEach(node.name.elements, checkSourceElement); + } + // For a parameter declaration with an initializer, error and exit if the containing function doesn't have a body + if (node.initializer && isPartOfParameterDeclaration(node) && nodeIsMissing((getContainingFunction(node) as FunctionLikeDeclaration).body)) { + error(node, Diagnostics.A_parameter_initializer_is_only_allowed_in_a_function_or_constructor_implementation); + return; + } + // For a binding pattern, validate the initializer and exit + if (isBindingPattern(node.name)) { + if (isInAmbientOrTypeNode(node)) { + return; + } + const needCheckInitializer = hasOnlyExpressionInitializer(node) && node.initializer && node.parent.parent.kind !== SyntaxKind.ForInStatement; + const needCheckWidenedType = !some(node.name.elements, not(isOmittedExpression)); + if (needCheckInitializer || needCheckWidenedType) { + // Don't validate for-in initializer as it is already an error + const widenedType = getWidenedTypeForVariableLikeDeclaration(node); + if (needCheckInitializer) { + const initializerType = checkExpressionCached(node.initializer); + if (strictNullChecks && needCheckWidenedType) { + checkNonNullNonVoidType(initializerType, node); + } + else { + checkTypeAssignableToAndOptionallyElaborate(initializerType, getWidenedTypeForVariableLikeDeclaration(node), node, node.initializer); + } + } + // check the binding pattern with empty elements + if (needCheckWidenedType) { + if (isArrayBindingPattern(node.name)) { + checkIteratedTypeOrElementType(IterationUse.Destructuring, widenedType, undefinedType, node); + } + else if (strictNullChecks) { + checkNonNullNonVoidType(widenedType, node); + } + } + } + return; + } + // For a commonjs `const x = require`, validate the alias and exit + const symbol = getSymbolOfDeclaration(node); + if (symbol.flags & SymbolFlags.Alias && (isVariableDeclarationInitializedToBareOrAccessedRequire(node) || isBindingElementOfBareOrAccessedRequire(node))) { + checkAliasSymbol(node); + return; + } + + const type = convertAutoToAny(getTypeOfSymbol(symbol)); + if (node === symbol.valueDeclaration) { + // Node is the primary declaration of the symbol, just validate the initializer + // Don't validate for-in initializer as it is already an error + const initializer = hasOnlyExpressionInitializer(node) && getEffectiveInitializer(node); + if (initializer) { + const isJSObjectLiteralInitializer = isInJSFile(node) && + isObjectLiteralExpression(initializer) && + (initializer.properties.length === 0 || isPrototypeAccess(node.name)) && + !!symbol.exports?.size; + if (!isJSObjectLiteralInitializer && node.parent.parent.kind !== SyntaxKind.ForInStatement) { + const initializerType = checkExpressionCached(initializer); + checkTypeAssignableToAndOptionallyElaborate(initializerType, type, node, initializer, /*headMessage*/ undefined); + const blockScopeKind = getCombinedNodeFlagsCached(node) & NodeFlags.BlockScoped; + if (blockScopeKind === NodeFlags.AwaitUsing) { + const globalAsyncDisposableType = getGlobalAsyncDisposableType(/*reportErrors*/ true); + const globalDisposableType = getGlobalDisposableType(/*reportErrors*/ true); + if (globalAsyncDisposableType !== emptyObjectType && globalDisposableType !== emptyObjectType) { + const optionalDisposableType = getUnionType([globalAsyncDisposableType, globalDisposableType, nullType, undefinedType]); + checkTypeAssignableTo(initializerType, optionalDisposableType, initializer, Diagnostics.The_initializer_of_an_await_using_declaration_must_be_either_an_object_with_a_Symbol_asyncDispose_or_Symbol_dispose_method_or_be_null_or_undefined); + } + } + else if (blockScopeKind === NodeFlags.Using) { + const globalDisposableType = getGlobalDisposableType(/*reportErrors*/ true); + if (globalDisposableType !== emptyObjectType) { + const optionalDisposableType = getUnionType([globalDisposableType, nullType, undefinedType]); + checkTypeAssignableTo(initializerType, optionalDisposableType, initializer, Diagnostics.The_initializer_of_a_using_declaration_must_be_either_an_object_with_a_Symbol_dispose_method_or_be_null_or_undefined); + } + } + } + } + if (symbol.declarations && symbol.declarations.length > 1) { + if (some(symbol.declarations, d => d !== node && isVariableLike(d) && !areDeclarationFlagsIdentical(d, node))) { + error(node.name, Diagnostics.All_declarations_of_0_must_have_identical_modifiers, declarationNameToString(node.name)); + } + } + } + else { + // Node is a secondary declaration, check that type is identical to primary declaration and check that + // initializer is consistent with type associated with the node + const declarationType = convertAutoToAny(getWidenedTypeForVariableLikeDeclaration(node)); + + if ( + !isErrorType(type) && !isErrorType(declarationType) && + !isTypeIdenticalTo(type, declarationType) && + !(symbol.flags & SymbolFlags.Assignment) + ) { + errorNextVariableOrPropertyDeclarationMustHaveSameType(symbol.valueDeclaration, type, node, declarationType); + } + if (hasOnlyExpressionInitializer(node) && node.initializer) { + checkTypeAssignableToAndOptionallyElaborate(checkExpressionCached(node.initializer), declarationType, node, node.initializer, /*headMessage*/ undefined); + } + if (symbol.valueDeclaration && !areDeclarationFlagsIdentical(node, symbol.valueDeclaration)) { + error(node.name, Diagnostics.All_declarations_of_0_must_have_identical_modifiers, declarationNameToString(node.name)); + } + } + if (node.kind !== SyntaxKind.PropertyDeclaration && node.kind !== SyntaxKind.PropertySignature) { + // We know we don't have a binding pattern or computed name here + checkExportsOnMergedDeclarations(node); + if (node.kind === SyntaxKind.VariableDeclaration || node.kind === SyntaxKind.BindingElement) { + checkVarDeclaredNamesNotShadowed(node); + } + checkCollisionsForDeclarationName(node, node.name); + } + } + + function errorNextVariableOrPropertyDeclarationMustHaveSameType(firstDeclaration: Declaration | undefined, firstType: Type, nextDeclaration: Declaration, nextType: Type): void { + const nextDeclarationName = getNameOfDeclaration(nextDeclaration); + const message = nextDeclaration.kind === SyntaxKind.PropertyDeclaration || nextDeclaration.kind === SyntaxKind.PropertySignature + ? Diagnostics.Subsequent_property_declarations_must_have_the_same_type_Property_0_must_be_of_type_1_but_here_has_type_2 + : Diagnostics.Subsequent_variable_declarations_must_have_the_same_type_Variable_0_must_be_of_type_1_but_here_has_type_2; + const declName = declarationNameToString(nextDeclarationName); + const err = error( + nextDeclarationName, + message, + declName, + typeToString(firstType), + typeToString(nextType), + ); + if (firstDeclaration) { + addRelatedInfo(err, createDiagnosticForNode(firstDeclaration, Diagnostics._0_was_also_declared_here, declName)); + } + } + + function areDeclarationFlagsIdentical(left: Declaration, right: Declaration) { + if ( + (left.kind === SyntaxKind.Parameter && right.kind === SyntaxKind.VariableDeclaration) || + (left.kind === SyntaxKind.VariableDeclaration && right.kind === SyntaxKind.Parameter) + ) { + // Differences in optionality between parameters and variables are allowed. + return true; + } + + if (hasQuestionToken(left) !== hasQuestionToken(right)) { + return false; + } + + const interestingFlags = ModifierFlags.Private | + ModifierFlags.Protected | + ModifierFlags.Async | + ModifierFlags.Abstract | + ModifierFlags.Readonly | + ModifierFlags.Static; + + return getSelectedEffectiveModifierFlags(left, interestingFlags) === getSelectedEffectiveModifierFlags(right, interestingFlags); + } + + function checkVariableDeclaration(node: VariableDeclaration) { + tracing?.push(tracing.Phase.Check, "checkVariableDeclaration", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); + checkGrammarVariableDeclaration(node); + checkVariableLikeDeclaration(node); + tracing?.pop(); + } + + function checkBindingElement(node: BindingElement) { + checkGrammarBindingElement(node); + return checkVariableLikeDeclaration(node); + } + + function checkVariableDeclarationList(node: VariableDeclarationList) { + const blockScopeKind = getCombinedNodeFlags(node) & NodeFlags.BlockScoped; + if ((blockScopeKind === NodeFlags.Using || blockScopeKind === NodeFlags.AwaitUsing) && languageVersion < LanguageFeatureMinimumTarget.UsingAndAwaitUsing) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.AddDisposableResourceAndDisposeResources); + } + + forEach(node.declarations, checkSourceElement); + } + + function checkVariableStatement(node: VariableStatement) { + // Grammar checking + if (!checkGrammarModifiers(node) && !checkGrammarVariableDeclarationList(node.declarationList)) checkGrammarForDisallowedBlockScopedVariableStatement(node); + checkVariableDeclarationList(node.declarationList); + } + + function checkExpressionStatement(node: ExpressionStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + checkExpression(node.expression); + } + + function checkIfStatement(node: IfStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + const type = checkTruthinessExpression(node.expression); + checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(node.expression, type, node.thenStatement); + checkSourceElement(node.thenStatement); + + if (node.thenStatement.kind === SyntaxKind.EmptyStatement) { + error(node.thenStatement, Diagnostics.The_body_of_an_if_statement_cannot_be_the_empty_statement); + } + + checkSourceElement(node.elseStatement); + } + + function checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(condExpr: Expression, condType: Type, body?: Statement | Expression) { + if (!strictNullChecks) return; + bothHelper(condExpr, body); + + function bothHelper(condExpr: Expression, body: Expression | Statement | undefined) { + condExpr = skipParentheses(condExpr); + + helper(condExpr, body); + + while (isBinaryExpression(condExpr) && (condExpr.operatorToken.kind === SyntaxKind.BarBarToken || condExpr.operatorToken.kind === SyntaxKind.QuestionQuestionToken)) { + condExpr = skipParentheses(condExpr.left); + helper(condExpr, body); + } + } + + function helper(condExpr: Expression, body: Expression | Statement | undefined) { + const location = isLogicalOrCoalescingBinaryExpression(condExpr) ? skipParentheses(condExpr.right) : condExpr; + if (isModuleExportsAccessExpression(location)) { + return; + } + if (isLogicalOrCoalescingBinaryExpression(location)) { + bothHelper(location, body); + return; + } + const type = location === condExpr ? condType : checkTruthinessExpression(location); + if (type.flags & TypeFlags.EnumLiteral && isPropertyAccessExpression(location) && (getNodeLinks(location.expression).resolvedSymbol ?? unknownSymbol).flags & SymbolFlags.Enum) { + // EnumLiteral type at condition with known value is always truthy or always falsy, likely an error + error(location, Diagnostics.This_condition_will_always_return_0, !!(type as LiteralType).value ? "true" : "false"); + return; + } + const isPropertyExpressionCast = isPropertyAccessExpression(location) && isTypeAssertion(location.expression); + if (!hasTypeFacts(type, TypeFacts.Truthy) || isPropertyExpressionCast) return; + + // While it technically should be invalid for any known-truthy value + // to be tested, we de-scope to functions and Promises unreferenced in + // the block as a heuristic to identify the most common bugs. There + // are too many false positives for values sourced from type + // definitions without strictNullChecks otherwise. + const callSignatures = getSignaturesOfType(type, SignatureKind.Call); + const isPromise = !!getAwaitedTypeOfPromise(type); + if (callSignatures.length === 0 && !isPromise) { + return; + } + + const testedNode = isIdentifier(location) ? location + : isPropertyAccessExpression(location) ? location.name + : undefined; + const testedSymbol = testedNode && getSymbolAtLocation(testedNode); + if (!testedSymbol && !isPromise) { + return; + } + + const isUsed = testedSymbol && isBinaryExpression(condExpr.parent) && isSymbolUsedInBinaryExpressionChain(condExpr.parent, testedSymbol) + || testedSymbol && body && isSymbolUsedInConditionBody(condExpr, body, testedNode, testedSymbol); + if (!isUsed) { + if (isPromise) { + errorAndMaybeSuggestAwait( + location, + /*maybeMissingAwait*/ true, + Diagnostics.This_condition_will_always_return_true_since_this_0_is_always_defined, + getTypeNameForErrorDisplay(type), + ); + } + else { + error(location, Diagnostics.This_condition_will_always_return_true_since_this_function_is_always_defined_Did_you_mean_to_call_it_instead); + } + } + } + } + + function isSymbolUsedInConditionBody(expr: Expression, body: Statement | Expression, testedNode: Node, testedSymbol: Symbol): boolean { + return !!forEachChild(body, function check(childNode): boolean | undefined { + if (isIdentifier(childNode)) { + const childSymbol = getSymbolAtLocation(childNode); + if (childSymbol && childSymbol === testedSymbol) { + // If the test was a simple identifier, the above check is sufficient + if (isIdentifier(expr) || isIdentifier(testedNode) && isBinaryExpression(testedNode.parent)) { + return true; + } + // Otherwise we need to ensure the symbol is called on the same target + let testedExpression = testedNode.parent; + let childExpression = childNode.parent; + while (testedExpression && childExpression) { + if ( + isIdentifier(testedExpression) && isIdentifier(childExpression) || + testedExpression.kind === SyntaxKind.ThisKeyword && childExpression.kind === SyntaxKind.ThisKeyword + ) { + return getSymbolAtLocation(testedExpression) === getSymbolAtLocation(childExpression); + } + else if (isPropertyAccessExpression(testedExpression) && isPropertyAccessExpression(childExpression)) { + if (getSymbolAtLocation(testedExpression.name) !== getSymbolAtLocation(childExpression.name)) { + return false; + } + childExpression = childExpression.expression; + testedExpression = testedExpression.expression; + } + else if (isCallExpression(testedExpression) && isCallExpression(childExpression)) { + childExpression = childExpression.expression; + testedExpression = testedExpression.expression; + } + else { + return false; + } + } + } + } + return forEachChild(childNode, check); + }); + } + + function isSymbolUsedInBinaryExpressionChain(node: Node, testedSymbol: Symbol): boolean { + while (isBinaryExpression(node) && node.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken) { + const isUsed = forEachChild(node.right, function visit(child): boolean | undefined { + if (isIdentifier(child)) { + const symbol = getSymbolAtLocation(child); + if (symbol && symbol === testedSymbol) { + return true; + } + } + return forEachChild(child, visit); + }); + if (isUsed) { + return true; + } + node = node.parent; + } + return false; + } + + function checkDoStatement(node: DoStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + checkSourceElement(node.statement); + checkTruthinessExpression(node.expression); + } + + function checkWhileStatement(node: WhileStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + checkTruthinessExpression(node.expression); + checkSourceElement(node.statement); + } + + function checkTruthinessOfType(type: Type, node: Node) { + if (type.flags & TypeFlags.Void) { + error(node, Diagnostics.An_expression_of_type_void_cannot_be_tested_for_truthiness); + } + return type; + } + + function checkTruthinessExpression(node: Expression, checkMode?: CheckMode) { + return checkTruthinessOfType(checkExpression(node, checkMode), node); + } + + function checkForStatement(node: ForStatement) { + // Grammar checking + if (!checkGrammarStatementInAmbientContext(node)) { + if (node.initializer && node.initializer.kind === SyntaxKind.VariableDeclarationList) { + checkGrammarVariableDeclarationList(node.initializer as VariableDeclarationList); + } + } + + if (node.initializer) { + if (node.initializer.kind === SyntaxKind.VariableDeclarationList) { + checkVariableDeclarationList(node.initializer as VariableDeclarationList); + } + else { + checkExpression(node.initializer); + } + } + + if (node.condition) checkTruthinessExpression(node.condition); + if (node.incrementor) checkExpression(node.incrementor); + checkSourceElement(node.statement); + if (node.locals) { + registerForUnusedIdentifiersCheck(node); + } + } + + function checkForOfStatement(node: ForOfStatement): void { + checkGrammarForInOrForOfStatement(node); + + const container = getContainingFunctionOrClassStaticBlock(node); + if (node.awaitModifier) { + if (container && isClassStaticBlockDeclaration(container)) { + grammarErrorOnNode(node.awaitModifier, Diagnostics.for_await_loops_cannot_be_used_inside_a_class_static_block); + } + else { + const functionFlags = getFunctionFlags(container); + if ((functionFlags & (FunctionFlags.Invalid | FunctionFlags.Async)) === FunctionFlags.Async && languageVersion < LanguageFeatureMinimumTarget.ForAwaitOf) { + // for..await..of in an async function or async generator function prior to ESNext requires the __asyncValues helper + checkExternalEmitHelpers(node, ExternalEmitHelpers.ForAwaitOfIncludes); + } + } + } + else if (compilerOptions.downlevelIteration && languageVersion < LanguageFeatureMinimumTarget.ForOf) { + // for..of prior to ES2015 requires the __values helper when downlevelIteration is enabled + checkExternalEmitHelpers(node, ExternalEmitHelpers.ForOfIncludes); + } + + // Check the LHS and RHS + // If the LHS is a declaration, just check it as a variable declaration, which will in turn check the RHS + // via checkRightHandSideOfForOf. + // If the LHS is an expression, check the LHS, as a destructuring assignment or as a reference. + // Then check that the RHS is assignable to it. + if (node.initializer.kind === SyntaxKind.VariableDeclarationList) { + checkVariableDeclarationList(node.initializer as VariableDeclarationList); + } + else { + const varExpr = node.initializer; + const iteratedType = checkRightHandSideOfForOf(node); + + // There may be a destructuring assignment on the left side + if (varExpr.kind === SyntaxKind.ArrayLiteralExpression || varExpr.kind === SyntaxKind.ObjectLiteralExpression) { + // iteratedType may be undefined. In this case, we still want to check the structure of + // varExpr, in particular making sure it's a valid LeftHandSideExpression. But we'd like + // to short circuit the type relation checking as much as possible, so we pass the unknownType. + checkDestructuringAssignment(varExpr, iteratedType || errorType); + } + else { + const leftType = checkExpression(varExpr); + checkReferenceExpression( + varExpr, + Diagnostics.The_left_hand_side_of_a_for_of_statement_must_be_a_variable_or_a_property_access, + Diagnostics.The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access, + ); + + // iteratedType will be undefined if the rightType was missing properties/signatures + // required to get its iteratedType (like [Symbol.iterator] or next). This may be + // because we accessed properties from anyType, or it may have led to an error inside + // getElementTypeOfIterable. + if (iteratedType) { + checkTypeAssignableToAndOptionallyElaborate(iteratedType, leftType, varExpr, node.expression); + } + } + } + + checkSourceElement(node.statement); + if (node.locals) { + registerForUnusedIdentifiersCheck(node); + } + } + + function checkForInStatement(node: ForInStatement) { + // Grammar checking + checkGrammarForInOrForOfStatement(node); + + const rightType = getNonNullableTypeIfNeeded(checkExpression(node.expression)); + // TypeScript 1.0 spec (April 2014): 5.4 + // In a 'for-in' statement of the form + // for (let VarDecl in Expr) Statement + // VarDecl must be a variable declaration without a type annotation that declares a variable of type Any, + // and Expr must be an expression of type Any, an object type, or a type parameter type. + if (node.initializer.kind === SyntaxKind.VariableDeclarationList) { + const variable = (node.initializer as VariableDeclarationList).declarations[0]; + if (variable && isBindingPattern(variable.name)) { + error(variable.name, Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_a_destructuring_pattern); + } + checkVariableDeclarationList(node.initializer as VariableDeclarationList); + } + else { + // In a 'for-in' statement of the form + // for (Var in Expr) Statement + // Var must be an expression classified as a reference of type Any or the String primitive type, + // and Expr must be an expression of type Any, an object type, or a type parameter type. + const varExpr = node.initializer; + const leftType = checkExpression(varExpr); + if (varExpr.kind === SyntaxKind.ArrayLiteralExpression || varExpr.kind === SyntaxKind.ObjectLiteralExpression) { + error(varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_a_destructuring_pattern); + } + else if (!isTypeAssignableTo(getIndexTypeOrString(rightType), leftType)) { + error(varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_must_be_of_type_string_or_any); + } + else { + // run check only former check succeeded to avoid cascading errors + checkReferenceExpression( + varExpr, + Diagnostics.The_left_hand_side_of_a_for_in_statement_must_be_a_variable_or_a_property_access, + Diagnostics.The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access, + ); + } + } + + // unknownType is returned i.e. if node.expression is identifier whose name cannot be resolved + // in this case error about missing name is already reported - do not report extra one + if (rightType === neverType || !isTypeAssignableToKind(rightType, TypeFlags.NonPrimitive | TypeFlags.InstantiableNonPrimitive)) { + error(node.expression, Diagnostics.The_right_hand_side_of_a_for_in_statement_must_be_of_type_any_an_object_type_or_a_type_parameter_but_here_has_type_0, typeToString(rightType)); + } + + checkSourceElement(node.statement); + if (node.locals) { + registerForUnusedIdentifiersCheck(node); + } + } + + function checkRightHandSideOfForOf(statement: ForOfStatement): Type { + const use = statement.awaitModifier ? IterationUse.ForAwaitOf : IterationUse.ForOf; + return checkIteratedTypeOrElementType(use, checkNonNullExpression(statement.expression), undefinedType, statement.expression); + } + + function checkIteratedTypeOrElementType(use: IterationUse, inputType: Type, sentType: Type, errorNode: Node | undefined): Type { + if (isTypeAny(inputType)) { + return inputType; + } + return getIteratedTypeOrElementType(use, inputType, sentType, errorNode, /*checkAssignability*/ true) || anyType; + } + + /** + * When consuming an iterable type in a for..of, spread, or iterator destructuring assignment + * we want to get the iterated type of an iterable for ES2015 or later, or the iterated type + * of a iterable (if defined globally) or element type of an array like for ES2015 or earlier. + */ + function getIteratedTypeOrElementType(use: IterationUse, inputType: Type, sentType: Type, errorNode: Node | undefined, checkAssignability: boolean): Type | undefined { + const allowAsyncIterables = (use & IterationUse.AllowsAsyncIterablesFlag) !== 0; + if (inputType === neverType) { + if (errorNode) { + reportTypeNotIterableError(errorNode, inputType, allowAsyncIterables); + } + return undefined; + } + + const uplevelIteration = languageVersion >= ScriptTarget.ES2015; + const downlevelIteration = !uplevelIteration && compilerOptions.downlevelIteration; + const possibleOutOfBounds = compilerOptions.noUncheckedIndexedAccess && !!(use & IterationUse.PossiblyOutOfBounds); + + // Get the iterated type of an `Iterable` or `IterableIterator` only in ES2015 + // or higher, when inside of an async generator or for-await-if, or when + // downlevelIteration is requested. + if (uplevelIteration || downlevelIteration || allowAsyncIterables) { + // We only report errors for an invalid iterable type in ES2015 or higher. + const iterationTypes = getIterationTypesOfIterable(inputType, use, uplevelIteration ? errorNode : undefined); + if (checkAssignability) { + if (iterationTypes) { + const diagnostic = use & IterationUse.ForOfFlag ? Diagnostics.Cannot_iterate_value_because_the_next_method_of_its_iterator_expects_type_1_but_for_of_will_always_send_0 : + use & IterationUse.SpreadFlag ? Diagnostics.Cannot_iterate_value_because_the_next_method_of_its_iterator_expects_type_1_but_array_spread_will_always_send_0 : + use & IterationUse.DestructuringFlag ? Diagnostics.Cannot_iterate_value_because_the_next_method_of_its_iterator_expects_type_1_but_array_destructuring_will_always_send_0 : + use & IterationUse.YieldStarFlag ? Diagnostics.Cannot_delegate_iteration_to_value_because_the_next_method_of_its_iterator_expects_type_1_but_the_containing_generator_will_always_send_0 : + undefined; + if (diagnostic) { + checkTypeAssignableTo(sentType, iterationTypes.nextType, errorNode, diagnostic); + } + } + } + if (iterationTypes || uplevelIteration) { + return possibleOutOfBounds ? includeUndefinedInIndexSignature(iterationTypes && iterationTypes.yieldType) : (iterationTypes && iterationTypes.yieldType); + } + } + + let arrayType = inputType; + let hasStringConstituent = false; + + // If strings are permitted, remove any string-like constituents from the array type. + // This allows us to find other non-string element types from an array unioned with + // a string. + if (use & IterationUse.AllowsStringInputFlag) { + if (arrayType.flags & TypeFlags.Union) { + // After we remove all types that are StringLike, we will know if there was a string constituent + // based on whether the result of filter is a new array. + const arrayTypes = (inputType as UnionType).types; + const filteredTypes = filter(arrayTypes, t => !(t.flags & TypeFlags.StringLike)); + if (filteredTypes !== arrayTypes) { + arrayType = getUnionType(filteredTypes, UnionReduction.Subtype); + } + } + else if (arrayType.flags & TypeFlags.StringLike) { + arrayType = neverType; + } + + hasStringConstituent = arrayType !== inputType; + if (hasStringConstituent) { + // Now that we've removed all the StringLike types, if no constituents remain, then the entire + // arrayOrStringType was a string. + if (arrayType.flags & TypeFlags.Never) { + return possibleOutOfBounds ? includeUndefinedInIndexSignature(stringType) : stringType; + } + } + } + + if (!isArrayLikeType(arrayType)) { + if (errorNode) { + // Which error we report depends on whether we allow strings or if there was a + // string constituent. For example, if the input type is number | string, we + // want to say that number is not an array type. But if the input was just + // number and string input is allowed, we want to say that number is not an + // array type or a string type. + const allowsStrings = !!(use & IterationUse.AllowsStringInputFlag) && !hasStringConstituent; + const [defaultDiagnostic, maybeMissingAwait] = getIterationDiagnosticDetails(allowsStrings, downlevelIteration); + errorAndMaybeSuggestAwait( + errorNode, + maybeMissingAwait && !!getAwaitedTypeOfPromise(arrayType), + defaultDiagnostic, + typeToString(arrayType), + ); + } + return hasStringConstituent ? possibleOutOfBounds ? includeUndefinedInIndexSignature(stringType) : stringType : undefined; + } + + const arrayElementType = getIndexTypeOfType(arrayType, numberType); + if (hasStringConstituent && arrayElementType) { + // This is just an optimization for the case where arrayOrStringType is string | string[] + if (arrayElementType.flags & TypeFlags.StringLike && !compilerOptions.noUncheckedIndexedAccess) { + return stringType; + } + + return getUnionType(possibleOutOfBounds ? [arrayElementType, stringType, undefinedType] : [arrayElementType, stringType], UnionReduction.Subtype); + } + + return (use & IterationUse.PossiblyOutOfBounds) ? includeUndefinedInIndexSignature(arrayElementType) : arrayElementType; + + function getIterationDiagnosticDetails(allowsStrings: boolean, downlevelIteration: boolean | undefined): [error: DiagnosticMessage, maybeMissingAwait: boolean] { + if (downlevelIteration) { + return allowsStrings + ? [Diagnostics.Type_0_is_not_an_array_type_or_a_string_type_or_does_not_have_a_Symbol_iterator_method_that_returns_an_iterator, true] + : [Diagnostics.Type_0_is_not_an_array_type_or_does_not_have_a_Symbol_iterator_method_that_returns_an_iterator, true]; + } + + const yieldType = getIterationTypeOfIterable(use, IterationTypeKind.Yield, inputType, /*errorNode*/ undefined); + + if (yieldType) { + return [Diagnostics.Type_0_can_only_be_iterated_through_when_using_the_downlevelIteration_flag_or_with_a_target_of_es2015_or_higher, false]; + } + + if (isES2015OrLaterIterable(inputType.symbol?.escapedName)) { + return [Diagnostics.Type_0_can_only_be_iterated_through_when_using_the_downlevelIteration_flag_or_with_a_target_of_es2015_or_higher, true]; + } + + return allowsStrings + ? [Diagnostics.Type_0_is_not_an_array_type_or_a_string_type, true] + : [Diagnostics.Type_0_is_not_an_array_type, true]; + } + } + + function isES2015OrLaterIterable(n: __String) { + switch (n) { + case "Float32Array": + case "Float64Array": + case "Int16Array": + case "Int32Array": + case "Int8Array": + case "NodeList": + case "Uint16Array": + case "Uint32Array": + case "Uint8Array": + case "Uint8ClampedArray": + return true; + } + return false; + } + + /** + * Gets the requested "iteration type" from an `Iterable`-like or `AsyncIterable`-like type. + */ + function getIterationTypeOfIterable(use: IterationUse, typeKind: IterationTypeKind, inputType: Type, errorNode: Node | undefined): Type | undefined { + if (isTypeAny(inputType)) { + return undefined; + } + + const iterationTypes = getIterationTypesOfIterable(inputType, use, errorNode); + return iterationTypes && iterationTypes[getIterationTypesKeyFromIterationTypeKind(typeKind)]; + } + + function createIterationTypes(yieldType: Type = neverType, returnType: Type = neverType, nextType: Type = unknownType): IterationTypes { + // `yieldType` and `returnType` are defaulted to `neverType` they each will be combined + // via `getUnionType` when merging iteration types. `nextType` is defined as `unknownType` + // as it is combined via `getIntersectionType` when merging iteration types. + + // Use the cache only for intrinsic types to keep it small as they are likely to be + // more frequently created (i.e. `Iterator`). Iteration types + // are also cached on the type they are requested for, so we shouldn't need to maintain + // the cache for less-frequently used types. + if ( + yieldType.flags & TypeFlags.Intrinsic && + returnType.flags & (TypeFlags.Any | TypeFlags.Never | TypeFlags.Unknown | TypeFlags.Void | TypeFlags.Undefined) && + nextType.flags & (TypeFlags.Any | TypeFlags.Never | TypeFlags.Unknown | TypeFlags.Void | TypeFlags.Undefined) + ) { + const id = getTypeListId([yieldType, returnType, nextType]); + let iterationTypes = iterationTypesCache.get(id); + if (!iterationTypes) { + iterationTypes = { yieldType, returnType, nextType }; + iterationTypesCache.set(id, iterationTypes); + } + return iterationTypes; + } + return { yieldType, returnType, nextType }; + } + + /** + * Combines multiple `IterationTypes` records. + * + * If `array` is empty or all elements are missing or are references to `noIterationTypes`, + * then `noIterationTypes` is returned. Otherwise, an `IterationTypes` record is returned + * for the combined iteration types. + */ + function combineIterationTypes(array: (IterationTypes | undefined)[]) { + let yieldTypes: Type[] | undefined; + let returnTypes: Type[] | undefined; + let nextTypes: Type[] | undefined; + for (const iterationTypes of array) { + if (iterationTypes === undefined || iterationTypes === noIterationTypes) { + continue; + } + if (iterationTypes === anyIterationTypes) { + return anyIterationTypes; + } + yieldTypes = append(yieldTypes, iterationTypes.yieldType); + returnTypes = append(returnTypes, iterationTypes.returnType); + nextTypes = append(nextTypes, iterationTypes.nextType); + } + if (yieldTypes || returnTypes || nextTypes) { + return createIterationTypes( + yieldTypes && getUnionType(yieldTypes), + returnTypes && getUnionType(returnTypes), + nextTypes && getIntersectionType(nextTypes), + ); + } + return noIterationTypes; + } + + function getCachedIterationTypes(type: Type, cacheKey: MatchingKeys) { + return (type as IterableOrIteratorType)[cacheKey]; + } + + function setCachedIterationTypes(type: Type, cacheKey: MatchingKeys, cachedTypes: IterationTypes) { + return (type as IterableOrIteratorType)[cacheKey] = cachedTypes; + } + + /** + * Gets the *yield*, *return*, and *next* types from an `Iterable`-like or `AsyncIterable`-like type. + * + * At every level that involves analyzing return types of signatures, we union the return types of all the signatures. + * + * Another thing to note is that at any step of this process, we could run into a dead end, + * meaning either the property is missing, or we run into the anyType. If either of these things + * happens, we return `undefined` to signal that we could not find the iteration type. If a property + * is missing, and the previous step did not result in `any`, then we also give an error if the + * caller requested it. Then the caller can decide what to do in the case where there is no iterated + * type. + * + * For a **for-of** statement, `yield*` (in a normal generator), spread, array + * destructuring, or normal generator we will only ever look for a `[Symbol.iterator]()` + * method. + * + * For an async generator we will only ever look at the `[Symbol.asyncIterator]()` method. + * + * For a **for-await-of** statement or a `yield*` in an async generator we will look for + * the `[Symbol.asyncIterator]()` method first, and then the `[Symbol.iterator]()` method. + */ + function getIterationTypesOfIterable(type: Type, use: IterationUse, errorNode: Node | undefined) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + if (!(type.flags & TypeFlags.Union)) { + const errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined = errorNode ? { errors: undefined } : undefined; + const iterationTypes = getIterationTypesOfIterableWorker(type, use, errorNode, errorOutputContainer); + if (iterationTypes === noIterationTypes) { + if (errorNode) { + const rootDiag = reportTypeNotIterableError(errorNode, type, !!(use & IterationUse.AllowsAsyncIterablesFlag)); + if (errorOutputContainer?.errors) { + addRelatedInfo(rootDiag, ...errorOutputContainer.errors); + } + } + return undefined; + } + else if (errorOutputContainer?.errors?.length) { + for (const diag of errorOutputContainer.errors) { + diagnostics.add(diag); + } + } + return iterationTypes; + } + + const cacheKey = use & IterationUse.AllowsAsyncIterablesFlag ? "iterationTypesOfAsyncIterable" : "iterationTypesOfIterable"; + const cachedTypes = getCachedIterationTypes(type, cacheKey); + if (cachedTypes) return cachedTypes === noIterationTypes ? undefined : cachedTypes; + + let allIterationTypes: IterationTypes[] | undefined; + for (const constituent of (type as UnionType).types) { + const errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined = errorNode ? { errors: undefined } : undefined; + const iterationTypes = getIterationTypesOfIterableWorker(constituent, use, errorNode, errorOutputContainer); + if (iterationTypes === noIterationTypes) { + if (errorNode) { + const rootDiag = reportTypeNotIterableError(errorNode, type, !!(use & IterationUse.AllowsAsyncIterablesFlag)); + if (errorOutputContainer?.errors) { + addRelatedInfo(rootDiag, ...errorOutputContainer.errors); + } + } + setCachedIterationTypes(type, cacheKey, noIterationTypes); + return undefined; + } + else if (errorOutputContainer?.errors?.length) { + for (const diag of errorOutputContainer.errors) { + diagnostics.add(diag); + } + } + + allIterationTypes = append(allIterationTypes, iterationTypes); + } + + const iterationTypes = allIterationTypes ? combineIterationTypes(allIterationTypes) : noIterationTypes; + setCachedIterationTypes(type, cacheKey, iterationTypes); + return iterationTypes === noIterationTypes ? undefined : iterationTypes; + } + + function getAsyncFromSyncIterationTypes(iterationTypes: IterationTypes, errorNode: Node | undefined) { + if (iterationTypes === noIterationTypes) return noIterationTypes; + if (iterationTypes === anyIterationTypes) return anyIterationTypes; + const { yieldType, returnType, nextType } = iterationTypes; + // if we're requesting diagnostics, report errors for a missing `Awaited`. + if (errorNode) { + getGlobalAwaitedSymbol(/*reportErrors*/ true); + } + return createIterationTypes( + getAwaitedType(yieldType, errorNode) || anyType, + getAwaitedType(returnType, errorNode) || anyType, + nextType, + ); + } + + /** + * Gets the *yield*, *return*, and *next* types from a non-union type. + * + * If we are unable to find the *yield*, *return*, and *next* types, `noIterationTypes` is + * returned to indicate to the caller that it should report an error. Otherwise, an + * `IterationTypes` record is returned. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterable` instead. + */ + function getIterationTypesOfIterableWorker(type: Type, use: IterationUse, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + // If we are reporting errors and encounter a cached `noIterationTypes`, we should ignore the cached value and continue as if nothing was cached. + // In addition, we should not cache any new results for this call. + let noCache = false; + + if (use & IterationUse.AllowsAsyncIterablesFlag) { + const iterationTypes = getIterationTypesOfIterableCached(type, asyncIterationTypesResolver) || + getIterationTypesOfIterableFast(type, asyncIterationTypesResolver); + if (iterationTypes) { + if (iterationTypes === noIterationTypes && errorNode) { + // ignore the cached value + noCache = true; + } + else { + return use & IterationUse.ForOfFlag ? + getAsyncFromSyncIterationTypes(iterationTypes, errorNode) : + iterationTypes; + } + } + } + + if (use & IterationUse.AllowsSyncIterablesFlag) { + let iterationTypes = getIterationTypesOfIterableCached(type, syncIterationTypesResolver) || + getIterationTypesOfIterableFast(type, syncIterationTypesResolver); + if (iterationTypes) { + if (iterationTypes === noIterationTypes && errorNode) { + // ignore the cached value + noCache = true; + } + else { + if (use & IterationUse.AllowsAsyncIterablesFlag) { + // for a sync iterable in an async context, only use the cached types if they are valid. + if (iterationTypes !== noIterationTypes) { + iterationTypes = getAsyncFromSyncIterationTypes(iterationTypes, errorNode); + return noCache ? iterationTypes : setCachedIterationTypes(type, "iterationTypesOfAsyncIterable", iterationTypes); + } + } + else { + return iterationTypes; + } + } + } + } + + if (use & IterationUse.AllowsAsyncIterablesFlag) { + const iterationTypes = getIterationTypesOfIterableSlow(type, asyncIterationTypesResolver, errorNode, errorOutputContainer, noCache); + if (iterationTypes !== noIterationTypes) { + return iterationTypes; + } + } + + if (use & IterationUse.AllowsSyncIterablesFlag) { + let iterationTypes = getIterationTypesOfIterableSlow(type, syncIterationTypesResolver, errorNode, errorOutputContainer, noCache); + if (iterationTypes !== noIterationTypes) { + if (use & IterationUse.AllowsAsyncIterablesFlag) { + iterationTypes = getAsyncFromSyncIterationTypes(iterationTypes, errorNode); + return noCache ? iterationTypes : setCachedIterationTypes(type, "iterationTypesOfAsyncIterable", iterationTypes); + } + else { + return iterationTypes; + } + } + } + + return noIterationTypes; + } + + /** + * Gets the *yield*, *return*, and *next* types of an `Iterable`-like or + * `AsyncIterable`-like type from the cache. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterable` instead. + */ + function getIterationTypesOfIterableCached(type: Type, resolver: IterationTypesResolver) { + return getCachedIterationTypes(type, resolver.iterableCacheKey); + } + + function getIterationTypesOfGlobalIterableType(globalType: Type, resolver: IterationTypesResolver) { + const globalIterationTypes = getIterationTypesOfIterableCached(globalType, resolver) || + getIterationTypesOfIterableSlow(globalType, resolver, /*errorNode*/ undefined, /*errorOutputContainer*/ undefined, /*noCache*/ false); + return globalIterationTypes === noIterationTypes ? defaultIterationTypes : globalIterationTypes; + } + + /** + * Gets the *yield*, *return*, and *next* types of an `Iterable`-like or `AsyncIterable`-like + * type from from common heuristics. + * + * If we previously analyzed this type and found no iteration types, `noIterationTypes` is + * returned. If we found iteration types, an `IterationTypes` record is returned. + * Otherwise, we return `undefined` to indicate to the caller it should perform a more + * exhaustive analysis. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterable` instead. + */ + function getIterationTypesOfIterableFast(type: Type, resolver: IterationTypesResolver) { + // As an optimization, if the type is an instantiation of one of the following global types, then + // just grab its related type argument: + // - `Iterable` or `AsyncIterable` + // - `IterableIterator` or `AsyncIterableIterator` + let globalType: Type; + if ( + isReferenceToType(type, globalType = resolver.getGlobalIterableType(/*reportErrors*/ false)) || + isReferenceToType(type, globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false)) + ) { + const [yieldType] = getTypeArguments(type as GenericType); + // The "return" and "next" types of `Iterable` and `IterableIterator` are defined by the + // iteration types of their `[Symbol.iterator]()` method. The same is true for their async cousins. + // While we define these as `any` and `undefined` in our libs by default, a custom lib *could* use + // different definitions. + const { returnType, nextType } = getIterationTypesOfGlobalIterableType(globalType, resolver); + return setCachedIterationTypes(type, resolver.iterableCacheKey, createIterationTypes(resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || yieldType, resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || returnType, nextType)); + } + + // As an optimization, if the type is an instantiation of the following global type, then + // just grab its related type arguments: + // - `Generator` or `AsyncGenerator` + if (isReferenceToType(type, resolver.getGlobalGeneratorType(/*reportErrors*/ false))) { + const [yieldType, returnType, nextType] = getTypeArguments(type as GenericType); + return setCachedIterationTypes(type, resolver.iterableCacheKey, createIterationTypes(resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || yieldType, resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || returnType, nextType)); + } + } + + function getPropertyNameForKnownSymbolName(symbolName: string): __String { + const ctorType = getGlobalESSymbolConstructorSymbol(/*reportErrors*/ false); + const uniqueType = ctorType && getTypeOfPropertyOfType(getTypeOfSymbol(ctorType), escapeLeadingUnderscores(symbolName)); + return uniqueType && isTypeUsableAsPropertyName(uniqueType) ? getPropertyNameFromType(uniqueType) : `__@${symbolName}` as __String; + } + + /** + * Gets the *yield*, *return*, and *next* types of an `Iterable`-like or `AsyncIterable`-like + * type from its members. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, `noIterationTypes` is returned. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterable` instead. + */ + function getIterationTypesOfIterableSlow(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined, noCache: boolean) { + const method = getPropertyOfType(type, getPropertyNameForKnownSymbolName(resolver.iteratorSymbolName)); + const methodType = method && !(method.flags & SymbolFlags.Optional) ? getTypeOfSymbol(method) : undefined; + if (isTypeAny(methodType)) { + return noCache ? anyIterationTypes : setCachedIterationTypes(type, resolver.iterableCacheKey, anyIterationTypes); + } + + const signatures = methodType ? getSignaturesOfType(methodType, SignatureKind.Call) : undefined; + if (!some(signatures)) { + return noCache ? noIterationTypes : setCachedIterationTypes(type, resolver.iterableCacheKey, noIterationTypes); + } + + const iteratorType = getIntersectionType(map(signatures, getReturnTypeOfSignature)); + const iterationTypes = getIterationTypesOfIteratorWorker(iteratorType, resolver, errorNode, errorOutputContainer, noCache) ?? noIterationTypes; + return noCache ? iterationTypes : setCachedIterationTypes(type, resolver.iterableCacheKey, iterationTypes); + } + + function reportTypeNotIterableError(errorNode: Node, type: Type, allowAsyncIterables: boolean): Diagnostic { + const message = allowAsyncIterables + ? Diagnostics.Type_0_must_have_a_Symbol_asyncIterator_method_that_returns_an_async_iterator + : Diagnostics.Type_0_must_have_a_Symbol_iterator_method_that_returns_an_iterator; + const suggestAwait = + // for (const x of Promise<...>) or [...Promise<...>] + !!getAwaitedTypeOfPromise(type) + // for (const x of AsyncIterable<...>) + || ( + !allowAsyncIterables && + isForOfStatement(errorNode.parent) && + errorNode.parent.expression === errorNode && + getGlobalAsyncIterableType(/*reportErrors*/ false) !== emptyGenericType && + isTypeAssignableTo(type, getGlobalAsyncIterableType(/*reportErrors*/ false)) + ); + return errorAndMaybeSuggestAwait(errorNode, suggestAwait, message, typeToString(type)); + } + + /** + * Gets the *yield*, *return*, and *next* types from an `Iterator`-like or `AsyncIterator`-like type. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, `undefined` is returned. + */ + function getIterationTypesOfIterator(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined) { + return getIterationTypesOfIteratorWorker(type, resolver, errorNode, errorOutputContainer, /*noCache*/ false); + } + + /** + * Gets the *yield*, *return*, and *next* types from an `Iterator`-like or `AsyncIterator`-like type. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, `undefined` is returned. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterator` instead. + */ + function getIterationTypesOfIteratorWorker(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined, noCache: boolean) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + let iterationTypes = getIterationTypesOfIteratorCached(type, resolver) || + getIterationTypesOfIteratorFast(type, resolver); + + if (iterationTypes === noIterationTypes && errorNode) { + iterationTypes = undefined; + noCache = true; + } + + iterationTypes ??= getIterationTypesOfIteratorSlow(type, resolver, errorNode, errorOutputContainer, noCache); + return iterationTypes === noIterationTypes ? undefined : iterationTypes; + } + + /** + * Gets the iteration types of an `Iterator`-like or `AsyncIterator`-like type from the + * cache. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterator` instead. + */ + function getIterationTypesOfIteratorCached(type: Type, resolver: IterationTypesResolver) { + return getCachedIterationTypes(type, resolver.iteratorCacheKey); + } + + /** + * Gets the iteration types of an `Iterator`-like or `AsyncIterator`-like type from the + * cache or from common heuristics. + * + * If we previously analyzed this type and found no iteration types, `noIterationTypes` is + * returned. If we found iteration types, an `IterationTypes` record is returned. + * Otherwise, we return `undefined` to indicate to the caller it should perform a more + * exhaustive analysis. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterator` instead. + */ + function getIterationTypesOfIteratorFast(type: Type, resolver: IterationTypesResolver) { + // As an optimization, if the type is an instantiation of one of the following global types, + // then just grab its related type argument: + // - `IterableIterator` or `AsyncIterableIterator` + // - `Iterator` or `AsyncIterator` + // - `Generator` or `AsyncGenerator` + const globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false); + if (isReferenceToType(type, globalType)) { + const [yieldType] = getTypeArguments(type as GenericType); + // The "return" and "next" types of `IterableIterator` and `AsyncIterableIterator` are defined by the + // iteration types of their `next`, `return`, and `throw` methods. While we define these as `any` + // and `undefined` in our libs by default, a custom lib *could* use different definitions. + const globalIterationTypes = getIterationTypesOfIteratorCached(globalType, resolver) || + getIterationTypesOfIteratorSlow(globalType, resolver, /*errorNode*/ undefined, /*errorOutputContainer*/ undefined, /*noCache*/ false); + const { returnType, nextType } = globalIterationTypes === noIterationTypes ? defaultIterationTypes : globalIterationTypes; + return setCachedIterationTypes(type, resolver.iteratorCacheKey, createIterationTypes(yieldType, returnType, nextType)); + } + if ( + isReferenceToType(type, resolver.getGlobalIteratorType(/*reportErrors*/ false)) || + isReferenceToType(type, resolver.getGlobalGeneratorType(/*reportErrors*/ false)) + ) { + const [yieldType, returnType, nextType] = getTypeArguments(type as GenericType); + return setCachedIterationTypes(type, resolver.iteratorCacheKey, createIterationTypes(yieldType, returnType, nextType)); + } + } + + function isIteratorResult(type: Type, kind: IterationTypeKind.Yield | IterationTypeKind.Return) { + // From https://tc39.github.io/ecma262/#sec-iteratorresult-interface: + // > [done] is the result status of an iterator `next` method call. If the end of the iterator was reached `done` is `true`. + // > If the end was not reached `done` is `false` and a value is available. + // > If a `done` property (either own or inherited) does not exist, it is consider to have the value `false`. + const doneType = getTypeOfPropertyOfType(type, "done" as __String) || falseType; + return isTypeAssignableTo(kind === IterationTypeKind.Yield ? falseType : trueType, doneType); + } + + function isYieldIteratorResult(type: Type) { + return isIteratorResult(type, IterationTypeKind.Yield); + } + + function isReturnIteratorResult(type: Type) { + return isIteratorResult(type, IterationTypeKind.Return); + } + + /** + * Gets the *yield* and *return* types of an `IteratorResult`-like type. + * + * If we are unable to determine a *yield* or a *return* type, `noIterationTypes` is + * returned to indicate to the caller that it should handle the error. Otherwise, an + * `IterationTypes` record is returned. + */ + function getIterationTypesOfIteratorResult(type: Type) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + const cachedTypes = getCachedIterationTypes(type, "iterationTypesOfIteratorResult"); + if (cachedTypes) { + return cachedTypes; + } + + // As an optimization, if the type is an instantiation of one of the global `IteratorYieldResult` + // or `IteratorReturnResult` types, then just grab its type argument. + if (isReferenceToType(type, getGlobalIteratorYieldResultType(/*reportErrors*/ false))) { + const yieldType = getTypeArguments(type as GenericType)[0]; + return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", createIterationTypes(yieldType, /*returnType*/ undefined, /*nextType*/ undefined)); + } + if (isReferenceToType(type, getGlobalIteratorReturnResultType(/*reportErrors*/ false))) { + const returnType = getTypeArguments(type as GenericType)[0]; + return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", createIterationTypes(/*yieldType*/ undefined, returnType, /*nextType*/ undefined)); + } + + // Choose any constituents that can produce the requested iteration type. + const yieldIteratorResult = filterType(type, isYieldIteratorResult); + const yieldType = yieldIteratorResult !== neverType ? getTypeOfPropertyOfType(yieldIteratorResult, "value" as __String) : undefined; + + const returnIteratorResult = filterType(type, isReturnIteratorResult); + const returnType = returnIteratorResult !== neverType ? getTypeOfPropertyOfType(returnIteratorResult, "value" as __String) : undefined; + + if (!yieldType && !returnType) { + return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", noIterationTypes); + } + + // From https://tc39.github.io/ecma262/#sec-iteratorresult-interface + // > ... If the iterator does not have a return value, `value` is `undefined`. In that case, the + // > `value` property may be absent from the conforming object if it does not inherit an explicit + // > `value` property. + return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", createIterationTypes(yieldType, returnType || voidType, /*nextType*/ undefined)); + } + + /** + * Gets the *yield*, *return*, and *next* types of a the `next()`, `return()`, or + * `throw()` method of an `Iterator`-like or `AsyncIterator`-like type. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, we return `undefined`. + */ + function getIterationTypesOfMethod(type: Type, resolver: IterationTypesResolver, methodName: "next" | "return" | "throw", errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined): IterationTypes | undefined { + const method = getPropertyOfType(type, methodName as __String); + + // Ignore 'return' or 'throw' if they are missing. + if (!method && methodName !== "next") { + return undefined; + } + + const methodType = method && !(methodName === "next" && (method.flags & SymbolFlags.Optional)) + ? methodName === "next" ? getTypeOfSymbol(method) : getTypeWithFacts(getTypeOfSymbol(method), TypeFacts.NEUndefinedOrNull) + : undefined; + + if (isTypeAny(methodType)) { + // `return()` and `throw()` don't provide a *next* type. + return methodName === "next" ? anyIterationTypes : anyIterationTypesExceptNext; + } + + // Both async and non-async iterators *must* have a `next` method. + const methodSignatures = methodType ? getSignaturesOfType(methodType, SignatureKind.Call) : emptyArray; + if (methodSignatures.length === 0) { + if (errorNode) { + const diagnostic = methodName === "next" + ? resolver.mustHaveANextMethodDiagnostic + : resolver.mustBeAMethodDiagnostic; + if (errorOutputContainer) { + errorOutputContainer.errors ??= []; + errorOutputContainer.errors.push(createDiagnosticForNode(errorNode, diagnostic, methodName)); + } + else { + error(errorNode, diagnostic, methodName); + } + } + return methodName === "next" ? noIterationTypes : undefined; + } + + // If the method signature comes exclusively from the global iterator or generator type, + // create iteration types from its type arguments like `getIterationTypesOfIteratorFast` + // does (so as to remove `undefined` from the next and return types). We arrive here when + // a contextual type for a generator was not a direct reference to one of those global types, + // but looking up `methodType` referred to one of them (and nothing else). E.g., in + // `interface SpecialIterator extends Iterator {}`, `SpecialIterator` is not a + // reference to `Iterator`, but its `next` member derives exclusively from `Iterator`. + if (methodType?.symbol && methodSignatures.length === 1) { + const globalGeneratorType = resolver.getGlobalGeneratorType(/*reportErrors*/ false); + const globalIteratorType = resolver.getGlobalIteratorType(/*reportErrors*/ false); + const isGeneratorMethod = globalGeneratorType.symbol?.members?.get(methodName as __String) === methodType.symbol; + const isIteratorMethod = !isGeneratorMethod && globalIteratorType.symbol?.members?.get(methodName as __String) === methodType.symbol; + if (isGeneratorMethod || isIteratorMethod) { + const globalType = isGeneratorMethod ? globalGeneratorType : globalIteratorType; + const { mapper } = methodType as AnonymousType; + return createIterationTypes( + getMappedType(globalType.typeParameters![0], mapper!), + getMappedType(globalType.typeParameters![1], mapper!), + methodName === "next" ? getMappedType(globalType.typeParameters![2], mapper!) : undefined, + ); + } + } + + // Extract the first parameter and return type of each signature. + let methodParameterTypes: Type[] | undefined; + let methodReturnTypes: Type[] | undefined; + for (const signature of methodSignatures) { + if (methodName !== "throw" && some(signature.parameters)) { + methodParameterTypes = append(methodParameterTypes, getTypeAtPosition(signature, 0)); + } + methodReturnTypes = append(methodReturnTypes, getReturnTypeOfSignature(signature)); + } + + // Resolve the *next* or *return* type from the first parameter of a `next()` or + // `return()` method, respectively. + let returnTypes: Type[] | undefined; + let nextType: Type | undefined; + if (methodName !== "throw") { + const methodParameterType = methodParameterTypes ? getUnionType(methodParameterTypes) : unknownType; + if (methodName === "next") { + // The value of `next(value)` is *not* awaited by async generators + nextType = methodParameterType; + } + else if (methodName === "return") { + // The value of `return(value)` *is* awaited by async generators + const resolvedMethodParameterType = resolver.resolveIterationType(methodParameterType, errorNode) || anyType; + returnTypes = append(returnTypes, resolvedMethodParameterType); + } + } + + // Resolve the *yield* and *return* types from the return type of the method (i.e. `IteratorResult`) + let yieldType: Type; + const methodReturnType = methodReturnTypes ? getIntersectionType(methodReturnTypes) : neverType; + const resolvedMethodReturnType = resolver.resolveIterationType(methodReturnType, errorNode) || anyType; + const iterationTypes = getIterationTypesOfIteratorResult(resolvedMethodReturnType); + if (iterationTypes === noIterationTypes) { + if (errorNode) { + if (errorOutputContainer) { + errorOutputContainer.errors ??= []; + errorOutputContainer.errors.push(createDiagnosticForNode(errorNode, resolver.mustHaveAValueDiagnostic, methodName)); + } + else { + error(errorNode, resolver.mustHaveAValueDiagnostic, methodName); + } + } + yieldType = anyType; + returnTypes = append(returnTypes, anyType); + } + else { + yieldType = iterationTypes.yieldType; + returnTypes = append(returnTypes, iterationTypes.returnType); + } + + return createIterationTypes(yieldType, getUnionType(returnTypes), nextType); + } + + /** + * Gets the *yield*, *return*, and *next* types of an `Iterator`-like or `AsyncIterator`-like + * type from its members. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, `noIterationTypes` is returned. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterator` instead. + */ + function getIterationTypesOfIteratorSlow(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined, noCache: boolean) { + const iterationTypes = combineIterationTypes([ + getIterationTypesOfMethod(type, resolver, "next", errorNode, errorOutputContainer), + getIterationTypesOfMethod(type, resolver, "return", errorNode, errorOutputContainer), + getIterationTypesOfMethod(type, resolver, "throw", errorNode, errorOutputContainer), + ]); + return noCache ? iterationTypes : setCachedIterationTypes(type, resolver.iteratorCacheKey, iterationTypes); + } + + /** + * Gets the requested "iteration type" from a type that is either `Iterable`-like, `Iterator`-like, + * `IterableIterator`-like, or `Generator`-like (for a non-async generator); or `AsyncIterable`-like, + * `AsyncIterator`-like, `AsyncIterableIterator`-like, or `AsyncGenerator`-like (for an async generator). + */ + function getIterationTypeOfGeneratorFunctionReturnType(kind: IterationTypeKind, returnType: Type, isAsyncGenerator: boolean): Type | undefined { + if (isTypeAny(returnType)) { + return undefined; + } + + const iterationTypes = getIterationTypesOfGeneratorFunctionReturnType(returnType, isAsyncGenerator); + return iterationTypes && iterationTypes[getIterationTypesKeyFromIterationTypeKind(kind)]; + } + + function getIterationTypesOfGeneratorFunctionReturnType(type: Type, isAsyncGenerator: boolean) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + const use = isAsyncGenerator ? IterationUse.AsyncGeneratorReturnType : IterationUse.GeneratorReturnType; + const resolver = isAsyncGenerator ? asyncIterationTypesResolver : syncIterationTypesResolver; + return getIterationTypesOfIterable(type, use, /*errorNode*/ undefined) || + getIterationTypesOfIterator(type, resolver, /*errorNode*/ undefined, /*errorOutputContainer*/ undefined); + } + + function checkBreakOrContinueStatement(node: BreakOrContinueStatement) { + // Grammar checking + if (!checkGrammarStatementInAmbientContext(node)) checkGrammarBreakOrContinueStatement(node); + + // TODO: Check that target label is valid + } + + function unwrapReturnType(returnType: Type, functionFlags: FunctionFlags) { + const isGenerator = !!(functionFlags & FunctionFlags.Generator); + const isAsync = !!(functionFlags & FunctionFlags.Async); + if (isGenerator) { + const returnIterationType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, returnType, isAsync); + if (!returnIterationType) { + return errorType; + } + return isAsync ? getAwaitedTypeNoAlias(unwrapAwaitedType(returnIterationType)) : returnIterationType; + } + return isAsync ? getAwaitedTypeNoAlias(returnType) || errorType : returnType; + } + + function isUnwrappedReturnTypeUndefinedVoidOrAny(func: SignatureDeclaration, returnType: Type): boolean { + const type = unwrapReturnType(returnType, getFunctionFlags(func)); + return !!(type && (maybeTypeOfKind(type, TypeFlags.Void) || type.flags & (TypeFlags.Any | TypeFlags.Undefined))); + } + + function checkReturnStatement(node: ReturnStatement) { + // Grammar checking + if (checkGrammarStatementInAmbientContext(node)) { + return; + } + + const container = getContainingFunctionOrClassStaticBlock(node); + if (container && isClassStaticBlockDeclaration(container)) { + grammarErrorOnFirstToken(node, Diagnostics.A_return_statement_cannot_be_used_inside_a_class_static_block); + return; + } + + if (!container) { + grammarErrorOnFirstToken(node, Diagnostics.A_return_statement_can_only_be_used_within_a_function_body); + return; + } + + const signature = getSignatureFromDeclaration(container); + const returnType = getReturnTypeOfSignature(signature); + const functionFlags = getFunctionFlags(container); + if (strictNullChecks || node.expression || returnType.flags & TypeFlags.Never) { + const exprType = node.expression ? checkExpressionCached(node.expression) : undefinedType; + if (container.kind === SyntaxKind.SetAccessor) { + if (node.expression) { + error(node, Diagnostics.Setters_cannot_return_a_value); + } + } + else if (container.kind === SyntaxKind.Constructor) { + if (node.expression && !checkTypeAssignableToAndOptionallyElaborate(exprType, returnType, node, node.expression)) { + error(node, Diagnostics.Return_type_of_constructor_signature_must_be_assignable_to_the_instance_type_of_the_class); + } + } + else if (getReturnTypeFromAnnotation(container)) { + const unwrappedReturnType = unwrapReturnType(returnType, functionFlags) ?? returnType; + const unwrappedExprType = functionFlags & FunctionFlags.Async + ? checkAwaitedType(exprType, /*withAlias*/ false, node, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member) + : exprType; + if (unwrappedReturnType) { + // If the function has a return type, but promisedType is + // undefined, an error will be reported in checkAsyncFunctionReturnType + // so we don't need to report one here. + checkTypeAssignableToAndOptionallyElaborate(unwrappedExprType, unwrappedReturnType, node, node.expression); + } + } + } + else if (container.kind !== SyntaxKind.Constructor && compilerOptions.noImplicitReturns && !isUnwrappedReturnTypeUndefinedVoidOrAny(container, returnType)) { + // The function has a return type, but the return statement doesn't have an expression. + error(node, Diagnostics.Not_all_code_paths_return_a_value); + } + } + + function checkWithStatement(node: WithStatement) { + // Grammar checking for withStatement + if (!checkGrammarStatementInAmbientContext(node)) { + if (node.flags & NodeFlags.AwaitContext) { + grammarErrorOnFirstToken(node, Diagnostics.with_statements_are_not_allowed_in_an_async_function_block); + } + } + + checkExpression(node.expression); + + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + const start = getSpanOfTokenAtPosition(sourceFile, node.pos).start; + const end = node.statement.pos; + grammarErrorAtPos(sourceFile, start, end - start, Diagnostics.The_with_statement_is_not_supported_All_symbols_in_a_with_block_will_have_type_any); + } + } + + function checkSwitchStatement(node: SwitchStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + let firstDefaultClause: CaseOrDefaultClause; + let hasDuplicateDefaultClause = false; + + const expressionType = checkExpression(node.expression); + + forEach(node.caseBlock.clauses, clause => { + // Grammar check for duplicate default clauses, skip if we already report duplicate default clause + if (clause.kind === SyntaxKind.DefaultClause && !hasDuplicateDefaultClause) { + if (firstDefaultClause === undefined) { + firstDefaultClause = clause; + } + else { + grammarErrorOnNode(clause, Diagnostics.A_default_clause_cannot_appear_more_than_once_in_a_switch_statement); + hasDuplicateDefaultClause = true; + } + } + + if (clause.kind === SyntaxKind.CaseClause) { + addLazyDiagnostic(createLazyCaseClauseDiagnostics(clause)); + } + forEach(clause.statements, checkSourceElement); + if (compilerOptions.noFallthroughCasesInSwitch && clause.fallthroughFlowNode && isReachableFlowNode(clause.fallthroughFlowNode)) { + error(clause, Diagnostics.Fallthrough_case_in_switch); + } + + function createLazyCaseClauseDiagnostics(clause: CaseClause) { + return () => { + // TypeScript 1.0 spec (April 2014): 5.9 + // In a 'switch' statement, each 'case' expression must be of a type that is comparable + // to or from the type of the 'switch' expression. + const caseType = checkExpression(clause.expression); + + if (!isTypeEqualityComparableTo(expressionType, caseType)) { + // expressionType is not comparable to caseType, try the reversed check and report errors if it fails + checkTypeComparableTo(caseType, expressionType, clause.expression, /*headMessage*/ undefined); + } + }; + } + }); + if (node.caseBlock.locals) { + registerForUnusedIdentifiersCheck(node.caseBlock); + } + } + + function checkLabeledStatement(node: LabeledStatement) { + // Grammar checking + if (!checkGrammarStatementInAmbientContext(node)) { + findAncestor(node.parent, current => { + if (isFunctionLike(current)) { + return "quit"; + } + if (current.kind === SyntaxKind.LabeledStatement && (current as LabeledStatement).label.escapedText === node.label.escapedText) { + grammarErrorOnNode(node.label, Diagnostics.Duplicate_label_0, getTextOfNode(node.label)); + return true; + } + return false; + }); + } + + // ensure that label is unique + checkSourceElement(node.statement); + } + + function checkThrowStatement(node: ThrowStatement) { + // Grammar checking + if (!checkGrammarStatementInAmbientContext(node)) { + if (isIdentifier(node.expression) && !node.expression.escapedText) { + grammarErrorAfterFirstToken(node, Diagnostics.Line_break_not_permitted_here); + } + } + + if (node.expression) { + checkExpression(node.expression); + } + } + + function checkTryStatement(node: TryStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + checkBlock(node.tryBlock); + const catchClause = node.catchClause; + if (catchClause) { + // Grammar checking + if (catchClause.variableDeclaration) { + const declaration = catchClause.variableDeclaration; + checkVariableLikeDeclaration(declaration); + const typeNode = getEffectiveTypeAnnotationNode(declaration); + if (typeNode) { + const type = getTypeFromTypeNode(typeNode); + if (type && !(type.flags & TypeFlags.AnyOrUnknown)) { + grammarErrorOnFirstToken(typeNode, Diagnostics.Catch_clause_variable_type_annotation_must_be_any_or_unknown_if_specified); + } + } + else if (declaration.initializer) { + grammarErrorOnFirstToken(declaration.initializer, Diagnostics.Catch_clause_variable_cannot_have_an_initializer); + } + else { + const blockLocals = catchClause.block.locals; + if (blockLocals) { + forEachKey(catchClause.locals!, caughtName => { + const blockLocal = blockLocals.get(caughtName); + if (blockLocal?.valueDeclaration && (blockLocal.flags & SymbolFlags.BlockScopedVariable) !== 0) { + grammarErrorOnNode(blockLocal.valueDeclaration, Diagnostics.Cannot_redeclare_identifier_0_in_catch_clause, unescapeLeadingUnderscores(caughtName)); + } + }); + } + } + } + + checkBlock(catchClause.block); + } + + if (node.finallyBlock) { + checkBlock(node.finallyBlock); + } + } + + function checkIndexConstraints(type: Type, symbol: Symbol, isStaticIndex?: boolean) { + const indexInfos = getIndexInfosOfType(type); + if (indexInfos.length === 0) { + return; + } + for (const prop of getPropertiesOfObjectType(type)) { + if (!(isStaticIndex && prop.flags & SymbolFlags.Prototype)) { + checkIndexConstraintForProperty(type, prop, getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique, /*includeNonPublic*/ true), getNonMissingTypeOfSymbol(prop)); + } + } + const typeDeclaration = symbol.valueDeclaration; + if (typeDeclaration && isClassLike(typeDeclaration)) { + for (const member of typeDeclaration.members) { + // Only process instance properties with computed names here. Static properties cannot be in conflict with indexers, + // and properties with literal names were already checked. + if (!isStatic(member) && !hasBindableName(member)) { + const symbol = getSymbolOfDeclaration(member); + checkIndexConstraintForProperty(type, symbol, getTypeOfExpression((member as DynamicNamedDeclaration).name.expression), getNonMissingTypeOfSymbol(symbol)); + } + } + } + if (indexInfos.length > 1) { + for (const info of indexInfos) { + checkIndexConstraintForIndexSignature(type, info); + } + } + } + + function checkIndexConstraintForProperty(type: Type, prop: Symbol, propNameType: Type, propType: Type) { + const declaration = prop.valueDeclaration; + const name = getNameOfDeclaration(declaration); + if (name && isPrivateIdentifier(name)) { + return; + } + const indexInfos = getApplicableIndexInfos(type, propNameType); + const interfaceDeclaration = getObjectFlags(type) & ObjectFlags.Interface ? getDeclarationOfKind(type.symbol, SyntaxKind.InterfaceDeclaration) : undefined; + const propDeclaration = declaration && declaration.kind === SyntaxKind.BinaryExpression || + name && name.kind === SyntaxKind.ComputedPropertyName ? declaration : undefined; + const localPropDeclaration = getParentOfSymbol(prop) === type.symbol ? declaration : undefined; + for (const info of indexInfos) { + const localIndexDeclaration = info.declaration && getParentOfSymbol(getSymbolOfDeclaration(info.declaration)) === type.symbol ? info.declaration : undefined; + // We check only when (a) the property is declared in the containing type, or (b) the applicable index signature is declared + // in the containing type, or (c) the containing type is an interface and no base interface contains both the property and + // the index signature (i.e. property and index signature are declared in separate inherited interfaces). + const errorNode = localPropDeclaration || localIndexDeclaration || + (interfaceDeclaration && !some(getBaseTypes(type as InterfaceType), base => !!getPropertyOfObjectType(base, prop.escapedName) && !!getIndexTypeOfType(base, info.keyType)) ? interfaceDeclaration : undefined); + if (errorNode && !isTypeAssignableTo(propType, info.type)) { + const diagnostic = createError(errorNode, Diagnostics.Property_0_of_type_1_is_not_assignable_to_2_index_type_3, symbolToString(prop), typeToString(propType), typeToString(info.keyType), typeToString(info.type)); + if (propDeclaration && errorNode !== propDeclaration) { + addRelatedInfo(diagnostic, createDiagnosticForNode(propDeclaration, Diagnostics._0_is_declared_here, symbolToString(prop))); + } + diagnostics.add(diagnostic); + } + } + } + + function checkIndexConstraintForIndexSignature(type: Type, checkInfo: IndexInfo) { + const declaration = checkInfo.declaration; + const indexInfos = getApplicableIndexInfos(type, checkInfo.keyType); + const interfaceDeclaration = getObjectFlags(type) & ObjectFlags.Interface ? getDeclarationOfKind(type.symbol, SyntaxKind.InterfaceDeclaration) : undefined; + const localCheckDeclaration = declaration && getParentOfSymbol(getSymbolOfDeclaration(declaration)) === type.symbol ? declaration : undefined; + for (const info of indexInfos) { + if (info === checkInfo) continue; + const localIndexDeclaration = info.declaration && getParentOfSymbol(getSymbolOfDeclaration(info.declaration)) === type.symbol ? info.declaration : undefined; + // We check only when (a) the check index signature is declared in the containing type, or (b) the applicable index + // signature is declared in the containing type, or (c) the containing type is an interface and no base interface contains + // both index signatures (i.e. the index signatures are declared in separate inherited interfaces). + const errorNode = localCheckDeclaration || localIndexDeclaration || + (interfaceDeclaration && !some(getBaseTypes(type as InterfaceType), base => !!getIndexInfoOfType(base, checkInfo.keyType) && !!getIndexTypeOfType(base, info.keyType)) ? interfaceDeclaration : undefined); + if (errorNode && !isTypeAssignableTo(checkInfo.type, info.type)) { + error(errorNode, Diagnostics._0_index_type_1_is_not_assignable_to_2_index_type_3, typeToString(checkInfo.keyType), typeToString(checkInfo.type), typeToString(info.keyType), typeToString(info.type)); + } + } + } + + function checkTypeNameIsReserved(name: Identifier, message: DiagnosticMessage): void { + // TS 1.0 spec (April 2014): 3.6.1 + // The predefined type keywords are reserved and cannot be used as names of user defined types. + switch (name.escapedText) { + case "any": + case "unknown": + case "never": + case "number": + case "bigint": + case "boolean": + case "string": + case "symbol": + case "void": + case "object": + case "undefined": + error(name, message, name.escapedText as string); + } + } + + /** + * The name cannot be used as 'Object' of user defined types with special target. + */ + function checkClassNameCollisionWithObject(name: Identifier): void { + if ( + languageVersion >= ScriptTarget.ES5 && name.escapedText === "Object" + && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(name).impliedNodeFormat === ModuleKind.CommonJS) + ) { + error(name, Diagnostics.Class_name_cannot_be_Object_when_targeting_ES5_with_module_0, ModuleKind[moduleKind]); // https://github.com/Microsoft/TypeScript/issues/17494 + } + } + + function checkUnmatchedJSDocParameters(node: SignatureDeclaration) { + const jsdocParameters = filter(getJSDocTags(node), isJSDocParameterTag); + if (!length(jsdocParameters)) return; + + const isJs = isInJSFile(node); + const parameters = new Set<__String>(); + const excludedParameters = new Set(); + forEach(node.parameters, ({ name }, index) => { + if (isIdentifier(name)) { + parameters.add(name.escapedText); + } + if (isBindingPattern(name)) { + excludedParameters.add(index); + } + }); + + const containsArguments = containsArgumentsReference(node); + if (containsArguments) { + const lastJSDocParamIndex = jsdocParameters.length - 1; + const lastJSDocParam = jsdocParameters[lastJSDocParamIndex]; + if ( + isJs && lastJSDocParam && isIdentifier(lastJSDocParam.name) && lastJSDocParam.typeExpression && + lastJSDocParam.typeExpression.type && !parameters.has(lastJSDocParam.name.escapedText) && !excludedParameters.has(lastJSDocParamIndex) && !isArrayType(getTypeFromTypeNode(lastJSDocParam.typeExpression.type)) + ) { + error(lastJSDocParam.name, Diagnostics.JSDoc_param_tag_has_name_0_but_there_is_no_parameter_with_that_name_It_would_match_arguments_if_it_had_an_array_type, idText(lastJSDocParam.name)); + } + } + else { + forEach(jsdocParameters, ({ name, isNameFirst }, index) => { + if (excludedParameters.has(index) || isIdentifier(name) && parameters.has(name.escapedText)) { + return; + } + if (isQualifiedName(name)) { + if (isJs) { + error(name, Diagnostics.Qualified_name_0_is_not_allowed_without_a_leading_param_object_1, entityNameToString(name), entityNameToString(name.left)); + } + } + else { + if (!isNameFirst) { + errorOrSuggestion(isJs, name, Diagnostics.JSDoc_param_tag_has_name_0_but_there_is_no_parameter_with_that_name, idText(name)); + } + } + }); + } + } + + /** + * Check each type parameter and check that type parameters have no duplicate type parameter declarations + */ + function checkTypeParameters(typeParameterDeclarations: readonly TypeParameterDeclaration[] | undefined) { + let seenDefault = false; + if (typeParameterDeclarations) { + for (let i = 0; i < typeParameterDeclarations.length; i++) { + const node = typeParameterDeclarations[i]; + checkTypeParameter(node); + + addLazyDiagnostic(createCheckTypeParameterDiagnostic(node, i)); + } + } + + function createCheckTypeParameterDiagnostic(node: TypeParameterDeclaration, i: number) { + return () => { + if (node.default) { + seenDefault = true; + checkTypeParametersNotReferenced(node.default, typeParameterDeclarations!, i); + } + else if (seenDefault) { + error(node, Diagnostics.Required_type_parameters_may_not_follow_optional_type_parameters); + } + for (let j = 0; j < i; j++) { + if (typeParameterDeclarations![j].symbol === node.symbol) { + error(node.name, Diagnostics.Duplicate_identifier_0, declarationNameToString(node.name)); + } + } + }; + } + } + + /** Check that type parameter defaults only reference previously declared type parameters */ + function checkTypeParametersNotReferenced(root: TypeNode, typeParameters: readonly TypeParameterDeclaration[], index: number) { + visit(root); + function visit(node: Node) { + if (node.kind === SyntaxKind.TypeReference) { + const type = getTypeFromTypeReference(node as TypeReferenceNode); + if (type.flags & TypeFlags.TypeParameter) { + for (let i = index; i < typeParameters.length; i++) { + if (type.symbol === getSymbolOfDeclaration(typeParameters[i])) { + error(node, Diagnostics.Type_parameter_defaults_can_only_reference_previously_declared_type_parameters); + } + } + } + } + forEachChild(node, visit); + } + } + + /** Check that type parameter lists are identical across multiple declarations */ + function checkTypeParameterListsIdentical(symbol: Symbol) { + if (symbol.declarations && symbol.declarations.length === 1) { + return; + } + + const links = getSymbolLinks(symbol); + if (!links.typeParametersChecked) { + links.typeParametersChecked = true; + const declarations = getClassOrInterfaceDeclarationsOfSymbol(symbol); + if (!declarations || declarations.length <= 1) { + return; + } + + const type = getDeclaredTypeOfSymbol(symbol) as InterfaceType; + if (!areTypeParametersIdentical(declarations, type.localTypeParameters!, getEffectiveTypeParameterDeclarations)) { + // Report an error on every conflicting declaration. + const name = symbolToString(symbol); + for (const declaration of declarations) { + error(declaration.name, Diagnostics.All_declarations_of_0_must_have_identical_type_parameters, name); + } + } + } + } + + function areTypeParametersIdentical(declarations: readonly T[], targetParameters: TypeParameter[], getTypeParameterDeclarations: (node: T) => readonly TypeParameterDeclaration[]) { + const maxTypeArgumentCount = length(targetParameters); + const minTypeArgumentCount = getMinTypeArgumentCount(targetParameters); + + for (const declaration of declarations) { + // If this declaration has too few or too many type parameters, we report an error + const sourceParameters = getTypeParameterDeclarations(declaration); + const numTypeParameters = sourceParameters.length; + if (numTypeParameters < minTypeArgumentCount || numTypeParameters > maxTypeArgumentCount) { + return false; + } + + for (let i = 0; i < numTypeParameters; i++) { + const source = sourceParameters[i]; + const target = targetParameters[i]; + + // If the type parameter node does not have the same as the resolved type + // parameter at this position, we report an error. + if (source.name.escapedText !== target.symbol.escapedName) { + return false; + } + + // If the type parameter node does not have an identical constraint as the resolved + // type parameter at this position, we report an error. + const constraint = getEffectiveConstraintOfTypeParameter(source); + const sourceConstraint = constraint && getTypeFromTypeNode(constraint); + const targetConstraint = getConstraintOfTypeParameter(target); + // relax check if later interface augmentation has no constraint, it's more broad and is OK to merge with + // a more constrained interface (this could be generalized to a full hierarchy check, but that's maybe overkill) + if (sourceConstraint && targetConstraint && !isTypeIdenticalTo(sourceConstraint, targetConstraint)) { + return false; + } + + // If the type parameter node has a default and it is not identical to the default + // for the type parameter at this position, we report an error. + const sourceDefault = source.default && getTypeFromTypeNode(source.default); + const targetDefault = getDefaultFromTypeParameter(target); + if (sourceDefault && targetDefault && !isTypeIdenticalTo(sourceDefault, targetDefault)) { + return false; + } + } + } + + return true; + } + + function getFirstTransformableStaticClassElement(node: ClassLikeDeclaration) { + const willTransformStaticElementsOfDecoratedClass = !legacyDecorators && languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators && + classOrConstructorParameterIsDecorated(/*useLegacyDecorators*/ false, node); + const willTransformPrivateElementsOrClassStaticBlocks = languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators; + const willTransformInitializers = !emitStandardClassFields; + if (willTransformStaticElementsOfDecoratedClass || willTransformPrivateElementsOrClassStaticBlocks) { + for (const member of node.members) { + if (willTransformStaticElementsOfDecoratedClass && classElementOrClassElementParameterIsDecorated(/*useLegacyDecorators*/ false, member, node)) { + return firstOrUndefined(getDecorators(node)) ?? node; + } + else if (willTransformPrivateElementsOrClassStaticBlocks) { + if (isClassStaticBlockDeclaration(member)) { + return member; + } + else if (isStatic(member)) { + if ( + isPrivateIdentifierClassElementDeclaration(member) || + willTransformInitializers && isInitializedProperty(member) + ) { + return member; + } + } + } + } + } + } + + function checkClassExpressionExternalHelpers(node: ClassExpression) { + if (node.name) return; + + const parent = walkUpOuterExpressions(node); + if (!isNamedEvaluationSource(parent)) return; + + const willTransformESDecorators = !legacyDecorators && languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators; + let location: Node | undefined; + if (willTransformESDecorators && classOrConstructorParameterIsDecorated(/*useLegacyDecorators*/ false, node)) { + location = firstOrUndefined(getDecorators(node)) ?? node; + } + else { + location = getFirstTransformableStaticClassElement(node); + } + + if (location) { + checkExternalEmitHelpers(location, ExternalEmitHelpers.SetFunctionName); + if ((isPropertyAssignment(parent) || isPropertyDeclaration(parent) || isBindingElement(parent)) && isComputedPropertyName(parent.name)) { + checkExternalEmitHelpers(location, ExternalEmitHelpers.PropKey); + } + } + } + + function checkClassExpression(node: ClassExpression): Type { + checkClassLikeDeclaration(node); + checkNodeDeferred(node); + checkClassExpressionExternalHelpers(node); + return getTypeOfSymbol(getSymbolOfDeclaration(node)); + } + + function checkClassExpressionDeferred(node: ClassExpression) { + forEach(node.members, checkSourceElement); + registerForUnusedIdentifiersCheck(node); + } + + function checkClassDeclaration(node: ClassDeclaration) { + const firstDecorator = find(node.modifiers, isDecorator); + if (legacyDecorators && firstDecorator && some(node.members, p => hasStaticModifier(p) && isPrivateIdentifierClassElementDeclaration(p))) { + grammarErrorOnNode(firstDecorator, Diagnostics.Class_decorators_can_t_be_used_with_static_private_identifier_Consider_removing_the_experimental_decorator); + } + if (!node.name && !hasSyntacticModifier(node, ModifierFlags.Default)) { + grammarErrorOnFirstToken(node, Diagnostics.A_class_declaration_without_the_default_modifier_must_have_a_name); + } + checkClassLikeDeclaration(node); + forEach(node.members, checkSourceElement); + + registerForUnusedIdentifiersCheck(node); + } + + function checkClassLikeDeclaration(node: ClassLikeDeclaration) { + checkGrammarClassLikeDeclaration(node); + checkDecorators(node); + checkCollisionsForDeclarationName(node, node.name); + checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); + checkExportsOnMergedDeclarations(node); + const symbol = getSymbolOfDeclaration(node); + const type = getDeclaredTypeOfSymbol(symbol) as InterfaceType; + const typeWithThis = getTypeWithThisArgument(type); + const staticType = getTypeOfSymbol(symbol) as ObjectType; + checkTypeParameterListsIdentical(symbol); + checkFunctionOrConstructorSymbol(symbol); + checkClassForDuplicateDeclarations(node); + + // Only check for reserved static identifiers on non-ambient context. + const nodeInAmbientContext = !!(node.flags & NodeFlags.Ambient); + if (!nodeInAmbientContext) { + checkClassForStaticPropertyNameConflicts(node); + } + + const baseTypeNode = getEffectiveBaseTypeNode(node); + if (baseTypeNode) { + forEach(baseTypeNode.typeArguments, checkSourceElement); + if (languageVersion < LanguageFeatureMinimumTarget.Classes) { + checkExternalEmitHelpers(baseTypeNode.parent, ExternalEmitHelpers.Extends); + } + // check both @extends and extends if both are specified. + const extendsNode = getClassExtendsHeritageElement(node); + if (extendsNode && extendsNode !== baseTypeNode) { + checkExpression(extendsNode.expression); + } + + const baseTypes = getBaseTypes(type); + if (baseTypes.length) { + addLazyDiagnostic(() => { + const baseType = baseTypes[0]; + const baseConstructorType = getBaseConstructorTypeOfClass(type); + const staticBaseType = getApparentType(baseConstructorType); + checkBaseTypeAccessibility(staticBaseType, baseTypeNode); + checkSourceElement(baseTypeNode.expression); + if (some(baseTypeNode.typeArguments)) { + forEach(baseTypeNode.typeArguments, checkSourceElement); + for (const constructor of getConstructorsForTypeArguments(staticBaseType, baseTypeNode.typeArguments, baseTypeNode)) { + if (!checkTypeArgumentConstraints(baseTypeNode, constructor.typeParameters!)) { + break; + } + } + } + const baseWithThis = getTypeWithThisArgument(baseType, type.thisType); + if (!checkTypeAssignableTo(typeWithThis, baseWithThis, /*errorNode*/ undefined)) { + issueMemberSpecificError(node, typeWithThis, baseWithThis, Diagnostics.Class_0_incorrectly_extends_base_class_1); + } + else { + // Report static side error only when instance type is assignable + checkTypeAssignableTo(staticType, getTypeWithoutSignatures(staticBaseType), node.name || node, Diagnostics.Class_static_side_0_incorrectly_extends_base_class_static_side_1); + } + if (baseConstructorType.flags & TypeFlags.TypeVariable) { + if (!isMixinConstructorType(staticType)) { + error(node.name || node, Diagnostics.A_mixin_class_must_have_a_constructor_with_a_single_rest_parameter_of_type_any); + } + else { + const constructSignatures = getSignaturesOfType(baseConstructorType, SignatureKind.Construct); + if (constructSignatures.some(signature => signature.flags & SignatureFlags.Abstract) && !hasSyntacticModifier(node, ModifierFlags.Abstract)) { + error(node.name || node, Diagnostics.A_mixin_class_that_extends_from_a_type_variable_containing_an_abstract_construct_signature_must_also_be_declared_abstract); + } + } + } + + if (!(staticBaseType.symbol && staticBaseType.symbol.flags & SymbolFlags.Class) && !(baseConstructorType.flags & TypeFlags.TypeVariable)) { + // When the static base type is a "class-like" constructor function (but not actually a class), we verify + // that all instantiated base constructor signatures return the same type. + const constructors = getInstantiatedConstructorsForTypeArguments(staticBaseType, baseTypeNode.typeArguments, baseTypeNode); + if (forEach(constructors, sig => !isJSConstructor(sig.declaration) && !isTypeIdenticalTo(getReturnTypeOfSignature(sig), baseType))) { + error(baseTypeNode.expression, Diagnostics.Base_constructors_must_all_have_the_same_return_type); + } + } + checkKindsOfPropertyMemberOverrides(type, baseType); + }); + } + } + + checkMembersForOverrideModifier(node, type, typeWithThis, staticType); + + const implementedTypeNodes = getEffectiveImplementsTypeNodes(node); + if (implementedTypeNodes) { + for (const typeRefNode of implementedTypeNodes) { + if (!isEntityNameExpression(typeRefNode.expression) || isOptionalChain(typeRefNode.expression)) { + error(typeRefNode.expression, Diagnostics.A_class_can_only_implement_an_identifier_Slashqualified_name_with_optional_type_arguments); + } + checkTypeReferenceNode(typeRefNode); + addLazyDiagnostic(createImplementsDiagnostics(typeRefNode)); + } + } + + addLazyDiagnostic(() => { + checkIndexConstraints(type, symbol); + checkIndexConstraints(staticType, symbol, /*isStaticIndex*/ true); + checkTypeForDuplicateIndexSignatures(node); + checkPropertyInitialization(node); + }); + + function createImplementsDiagnostics(typeRefNode: ExpressionWithTypeArguments) { + return () => { + const t = getReducedType(getTypeFromTypeNode(typeRefNode)); + if (!isErrorType(t)) { + if (isValidBaseType(t)) { + const genericDiag = t.symbol && t.symbol.flags & SymbolFlags.Class ? + Diagnostics.Class_0_incorrectly_implements_class_1_Did_you_mean_to_extend_1_and_inherit_its_members_as_a_subclass : + Diagnostics.Class_0_incorrectly_implements_interface_1; + const baseWithThis = getTypeWithThisArgument(t, type.thisType); + if (!checkTypeAssignableTo(typeWithThis, baseWithThis, /*errorNode*/ undefined)) { + issueMemberSpecificError(node, typeWithThis, baseWithThis, genericDiag); + } + } + else { + error(typeRefNode, Diagnostics.A_class_can_only_implement_an_object_type_or_intersection_of_object_types_with_statically_known_members); + } + } + }; + } + } + + function checkMembersForOverrideModifier(node: ClassLikeDeclaration, type: InterfaceType, typeWithThis: Type, staticType: ObjectType) { + const baseTypeNode = getEffectiveBaseTypeNode(node); + const baseTypes = baseTypeNode && getBaseTypes(type); + const baseWithThis = baseTypes?.length ? getTypeWithThisArgument(first(baseTypes), type.thisType) : undefined; + const baseStaticType = getBaseConstructorTypeOfClass(type); + + for (const member of node.members) { + if (hasAmbientModifier(member)) { + continue; + } + + if (isConstructorDeclaration(member)) { + forEach(member.parameters, param => { + if (isParameterPropertyDeclaration(param, member)) { + checkExistingMemberForOverrideModifier( + node, + staticType, + baseStaticType, + baseWithThis, + type, + typeWithThis, + param, + /*memberIsParameterProperty*/ true, + ); + } + }); + } + checkExistingMemberForOverrideModifier( + node, + staticType, + baseStaticType, + baseWithThis, + type, + typeWithThis, + member, + /*memberIsParameterProperty*/ false, + ); + } + } + + /** + * @param member Existing member node to be checked. + * Note: `member` cannot be a synthetic node. + */ + function checkExistingMemberForOverrideModifier( + node: ClassLikeDeclaration, + staticType: ObjectType, + baseStaticType: Type, + baseWithThis: Type | undefined, + type: InterfaceType, + typeWithThis: Type, + member: ClassElement | ParameterPropertyDeclaration, + memberIsParameterProperty: boolean, + reportErrors = true, + ): MemberOverrideStatus { + const declaredProp = member.name + && getSymbolAtLocation(member.name) + || getSymbolAtLocation(member); + if (!declaredProp) { + return MemberOverrideStatus.Ok; + } + + return checkMemberForOverrideModifier( + node, + staticType, + baseStaticType, + baseWithThis, + type, + typeWithThis, + hasOverrideModifier(member), + hasAbstractModifier(member), + isStatic(member), + memberIsParameterProperty, + declaredProp, + reportErrors ? member : undefined, + ); + } + + /** + * Checks a class member declaration for either a missing or an invalid `override` modifier. + * Note: this function can be used for speculative checking, + * i.e. checking a member that does not yet exist in the program. + * An example of that would be to call this function in a completions scenario, + * when offering a method declaration as completion. + * @param errorNode The node where we should report an error, or undefined if we should not report errors. + */ + function checkMemberForOverrideModifier( + node: ClassLikeDeclaration, + staticType: ObjectType, + baseStaticType: Type, + baseWithThis: Type | undefined, + type: InterfaceType, + typeWithThis: Type, + memberHasOverrideModifier: boolean, + memberHasAbstractModifier: boolean, + memberIsStatic: boolean, + memberIsParameterProperty: boolean, + member: Symbol, + errorNode?: Node, + ): MemberOverrideStatus { + const isJs = isInJSFile(node); + const nodeInAmbientContext = !!(node.flags & NodeFlags.Ambient); + if (baseWithThis && (memberHasOverrideModifier || compilerOptions.noImplicitOverride)) { + const thisType = memberIsStatic ? staticType : typeWithThis; + const baseType = memberIsStatic ? baseStaticType : baseWithThis; + const prop = getPropertyOfType(thisType, member.escapedName); + const baseProp = getPropertyOfType(baseType, member.escapedName); + + const baseClassName = typeToString(baseWithThis); + if (prop && !baseProp && memberHasOverrideModifier) { + if (errorNode) { + const suggestion = getSuggestedSymbolForNonexistentClassMember(symbolName(member), baseType); // Again, using symbol name: note that's different from `symbol.escapedName` + suggestion ? + error( + errorNode, + isJs ? + Diagnostics.This_member_cannot_have_a_JSDoc_comment_with_an_override_tag_because_it_is_not_declared_in_the_base_class_0_Did_you_mean_1 : + Diagnostics.This_member_cannot_have_an_override_modifier_because_it_is_not_declared_in_the_base_class_0_Did_you_mean_1, + baseClassName, + symbolToString(suggestion), + ) : + error( + errorNode, + isJs ? + Diagnostics.This_member_cannot_have_a_JSDoc_comment_with_an_override_tag_because_it_is_not_declared_in_the_base_class_0 : + Diagnostics.This_member_cannot_have_an_override_modifier_because_it_is_not_declared_in_the_base_class_0, + baseClassName, + ); + } + return MemberOverrideStatus.HasInvalidOverride; + } + else if (prop && baseProp?.declarations && compilerOptions.noImplicitOverride && !nodeInAmbientContext) { + const baseHasAbstract = some(baseProp.declarations, hasAbstractModifier); + if (memberHasOverrideModifier) { + return MemberOverrideStatus.Ok; + } + + if (!baseHasAbstract) { + if (errorNode) { + const diag = memberIsParameterProperty ? + isJs ? + Diagnostics.This_parameter_property_must_have_a_JSDoc_comment_with_an_override_tag_because_it_overrides_a_member_in_the_base_class_0 : + Diagnostics.This_parameter_property_must_have_an_override_modifier_because_it_overrides_a_member_in_base_class_0 : + isJs ? + Diagnostics.This_member_must_have_a_JSDoc_comment_with_an_override_tag_because_it_overrides_a_member_in_the_base_class_0 : + Diagnostics.This_member_must_have_an_override_modifier_because_it_overrides_a_member_in_the_base_class_0; + error(errorNode, diag, baseClassName); + } + return MemberOverrideStatus.NeedsOverride; + } + else if (memberHasAbstractModifier && baseHasAbstract) { + if (errorNode) { + error(errorNode, Diagnostics.This_member_must_have_an_override_modifier_because_it_overrides_an_abstract_method_that_is_declared_in_the_base_class_0, baseClassName); + } + return MemberOverrideStatus.NeedsOverride; + } + } + } + else if (memberHasOverrideModifier) { + if (errorNode) { + const className = typeToString(type); + error( + errorNode, + isJs ? + Diagnostics.This_member_cannot_have_a_JSDoc_comment_with_an_override_tag_because_its_containing_class_0_does_not_extend_another_class : + Diagnostics.This_member_cannot_have_an_override_modifier_because_its_containing_class_0_does_not_extend_another_class, + className, + ); + } + return MemberOverrideStatus.HasInvalidOverride; + } + + return MemberOverrideStatus.Ok; + } + + function issueMemberSpecificError(node: ClassLikeDeclaration, typeWithThis: Type, baseWithThis: Type, broadDiag: DiagnosticMessage) { + // iterate over all implemented properties and issue errors on each one which isn't compatible, rather than the class as a whole, if possible + let issuedMemberError = false; + for (const member of node.members) { + if (isStatic(member)) { + continue; + } + const declaredProp = member.name && getSymbolAtLocation(member.name) || getSymbolAtLocation(member); + if (declaredProp) { + const prop = getPropertyOfType(typeWithThis, declaredProp.escapedName); + const baseProp = getPropertyOfType(baseWithThis, declaredProp.escapedName); + if (prop && baseProp) { + const rootChain = () => + chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.Property_0_in_type_1_is_not_assignable_to_the_same_property_in_base_type_2, + symbolToString(declaredProp), + typeToString(typeWithThis), + typeToString(baseWithThis), + ); + if (!checkTypeAssignableTo(getTypeOfSymbol(prop), getTypeOfSymbol(baseProp), member.name || member, /*headMessage*/ undefined, rootChain)) { + issuedMemberError = true; + } + } + } + } + if (!issuedMemberError) { + // check again with diagnostics to generate a less-specific error + checkTypeAssignableTo(typeWithThis, baseWithThis, node.name || node, broadDiag); + } + } + + function checkBaseTypeAccessibility(type: Type, node: ExpressionWithTypeArguments) { + const signatures = getSignaturesOfType(type, SignatureKind.Construct); + if (signatures.length) { + const declaration = signatures[0].declaration; + if (declaration && hasEffectiveModifier(declaration, ModifierFlags.Private)) { + const typeClassDeclaration = getClassLikeDeclarationOfSymbol(type.symbol)!; + if (!isNodeWithinClass(node, typeClassDeclaration)) { + error(node, Diagnostics.Cannot_extend_a_class_0_Class_constructor_is_marked_as_private, getFullyQualifiedName(type.symbol)); + } + } + } + } + + /** + * Checks a member declaration node to see if has a missing or invalid `override` modifier. + * @param node Class-like node where the member is declared. + * @param member Member declaration node. + * @param memberSymbol Member symbol. + * Note: `member` can be a synthetic node without a parent. + */ + function getMemberOverrideModifierStatus(node: ClassLikeDeclaration, member: ClassElement, memberSymbol: Symbol): MemberOverrideStatus { + if (!member.name) { + return MemberOverrideStatus.Ok; + } + + const classSymbol = getSymbolOfDeclaration(node); + const type = getDeclaredTypeOfSymbol(classSymbol) as InterfaceType; + const typeWithThis = getTypeWithThisArgument(type); + const staticType = getTypeOfSymbol(classSymbol) as ObjectType; + + const baseTypeNode = getEffectiveBaseTypeNode(node); + const baseTypes = baseTypeNode && getBaseTypes(type); + const baseWithThis = baseTypes?.length ? getTypeWithThisArgument(first(baseTypes), type.thisType) : undefined; + const baseStaticType = getBaseConstructorTypeOfClass(type); + + const memberHasOverrideModifier = member.parent + ? hasOverrideModifier(member) + : hasSyntacticModifier(member, ModifierFlags.Override); + + return checkMemberForOverrideModifier( + node, + staticType, + baseStaticType, + baseWithThis, + type, + typeWithThis, + memberHasOverrideModifier, + hasAbstractModifier(member), + isStatic(member), + /*memberIsParameterProperty*/ false, + memberSymbol, + ); + } + + function getTargetSymbol(s: Symbol) { + // if symbol is instantiated its flags are not copied from the 'target' + // so we'll need to get back original 'target' symbol to work with correct set of flags + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols have CheckFlags.Instantiated + return getCheckFlags(s) & CheckFlags.Instantiated ? (s as TransientSymbol).links.target! : s; + } + + function getClassOrInterfaceDeclarationsOfSymbol(symbol: Symbol) { + return filter(symbol.declarations, (d: Declaration): d is ClassDeclaration | InterfaceDeclaration => d.kind === SyntaxKind.ClassDeclaration || d.kind === SyntaxKind.InterfaceDeclaration); + } + + function checkKindsOfPropertyMemberOverrides(type: InterfaceType, baseType: BaseType): void { + // TypeScript 1.0 spec (April 2014): 8.2.3 + // A derived class inherits all members from its base class it doesn't override. + // Inheritance means that a derived class implicitly contains all non - overridden members of the base class. + // Both public and private property members are inherited, but only public property members can be overridden. + // A property member in a derived class is said to override a property member in a base class + // when the derived class property member has the same name and kind(instance or static) + // as the base class property member. + // The type of an overriding property member must be assignable(section 3.8.4) + // to the type of the overridden property member, or otherwise a compile - time error occurs. + // Base class instance member functions can be overridden by derived class instance member functions, + // but not by other kinds of members. + // Base class instance member variables and accessors can be overridden by + // derived class instance member variables and accessors, but not by other kinds of members. + + // NOTE: assignability is checked in checkClassDeclaration + const baseProperties = getPropertiesOfType(baseType); + + interface MemberInfo { + missedProperties: string[]; + baseTypeName: string; + typeName: string; + } + const notImplementedInfo = new Map(); + + basePropertyCheck: for (const baseProperty of baseProperties) { + const base = getTargetSymbol(baseProperty); + + if (base.flags & SymbolFlags.Prototype) { + continue; + } + const baseSymbol = getPropertyOfObjectType(type, base.escapedName); + if (!baseSymbol) { + continue; + } + const derived = getTargetSymbol(baseSymbol); + const baseDeclarationFlags = getDeclarationModifierFlagsFromSymbol(base); + + Debug.assert(!!derived, "derived should point to something, even if it is the base class' declaration."); + + // In order to resolve whether the inherited method was overridden in the base class or not, + // we compare the Symbols obtained. Since getTargetSymbol returns the symbol on the *uninstantiated* + // type declaration, derived and base resolve to the same symbol even in the case of generic classes. + if (derived === base) { + // derived class inherits base without override/redeclaration + const derivedClassDecl = getClassLikeDeclarationOfSymbol(type.symbol)!; + + // It is an error to inherit an abstract member without implementing it or being declared abstract. + // If there is no declaration for the derived class (as in the case of class expressions), + // then the class cannot be declared abstract. + if (baseDeclarationFlags & ModifierFlags.Abstract && (!derivedClassDecl || !hasSyntacticModifier(derivedClassDecl, ModifierFlags.Abstract))) { + // Searches other base types for a declaration that would satisfy the inherited abstract member. + // (The class may have more than one base type via declaration merging with an interface with the + // same name.) + for (const otherBaseType of getBaseTypes(type)) { + if (otherBaseType === baseType) continue; + const baseSymbol = getPropertyOfObjectType(otherBaseType, base.escapedName); + const derivedElsewhere = baseSymbol && getTargetSymbol(baseSymbol); + if (derivedElsewhere && derivedElsewhere !== base) { + continue basePropertyCheck; + } + } + const baseTypeName = typeToString(baseType); + const typeName = typeToString(type); + const basePropertyName = symbolToString(baseProperty); + const missedProperties = append(notImplementedInfo.get(derivedClassDecl)?.missedProperties, basePropertyName); + notImplementedInfo.set(derivedClassDecl, { baseTypeName, typeName, missedProperties }); + } + } + else { + // derived overrides base. + const derivedDeclarationFlags = getDeclarationModifierFlagsFromSymbol(derived); + if (baseDeclarationFlags & ModifierFlags.Private || derivedDeclarationFlags & ModifierFlags.Private) { + // either base or derived property is private - not override, skip it + continue; + } + + let errorMessage: DiagnosticMessage; + const basePropertyFlags = base.flags & SymbolFlags.PropertyOrAccessor; + const derivedPropertyFlags = derived.flags & SymbolFlags.PropertyOrAccessor; + if (basePropertyFlags && derivedPropertyFlags) { + // property/accessor is overridden with property/accessor + if ( + (getCheckFlags(base) & CheckFlags.Synthetic + ? base.declarations?.some(d => isPropertyAbstractOrInterface(d, baseDeclarationFlags)) + : base.declarations?.every(d => isPropertyAbstractOrInterface(d, baseDeclarationFlags))) + || getCheckFlags(base) & CheckFlags.Mapped + || derived.valueDeclaration && isBinaryExpression(derived.valueDeclaration) + ) { + // when the base property is abstract or from an interface, base/derived flags don't need to match + // for intersection properties, this must be true of *any* of the declarations, for others it must be true of *all* + // same when the derived property is from an assignment + continue; + } + + const overriddenInstanceProperty = basePropertyFlags !== SymbolFlags.Property && derivedPropertyFlags === SymbolFlags.Property; + const overriddenInstanceAccessor = basePropertyFlags === SymbolFlags.Property && derivedPropertyFlags !== SymbolFlags.Property; + if (overriddenInstanceProperty || overriddenInstanceAccessor) { + const errorMessage = overriddenInstanceProperty ? + Diagnostics._0_is_defined_as_an_accessor_in_class_1_but_is_overridden_here_in_2_as_an_instance_property : + Diagnostics._0_is_defined_as_a_property_in_class_1_but_is_overridden_here_in_2_as_an_accessor; + error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, symbolToString(base), typeToString(baseType), typeToString(type)); + } + else if (useDefineForClassFields) { + const uninitialized = derived.declarations?.find(d => d.kind === SyntaxKind.PropertyDeclaration && !(d as PropertyDeclaration).initializer); + if ( + uninitialized + && !(derived.flags & SymbolFlags.Transient) + && !(baseDeclarationFlags & ModifierFlags.Abstract) + && !(derivedDeclarationFlags & ModifierFlags.Abstract) + && !derived.declarations?.some(d => !!(d.flags & NodeFlags.Ambient)) + ) { + const constructor = findConstructorDeclaration(getClassLikeDeclarationOfSymbol(type.symbol)!); + const propName = (uninitialized as PropertyDeclaration).name; + if ( + (uninitialized as PropertyDeclaration).exclamationToken + || !constructor + || !isIdentifier(propName) + || !strictNullChecks + || !isPropertyInitializedInConstructor(propName, type, constructor) + ) { + const errorMessage = Diagnostics.Property_0_will_overwrite_the_base_property_in_1_If_this_is_intentional_add_an_initializer_Otherwise_add_a_declare_modifier_or_remove_the_redundant_declaration; + error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, symbolToString(base), typeToString(baseType)); + } + } + } + + // correct case + continue; + } + else if (isPrototypeProperty(base)) { + if (isPrototypeProperty(derived) || derived.flags & SymbolFlags.Property) { + // method is overridden with method or property -- correct case + continue; + } + else { + Debug.assert(!!(derived.flags & SymbolFlags.Accessor)); + errorMessage = Diagnostics.Class_0_defines_instance_member_function_1_but_extended_class_2_defines_it_as_instance_member_accessor; + } + } + else if (base.flags & SymbolFlags.Accessor) { + errorMessage = Diagnostics.Class_0_defines_instance_member_accessor_1_but_extended_class_2_defines_it_as_instance_member_function; + } + else { + errorMessage = Diagnostics.Class_0_defines_instance_member_property_1_but_extended_class_2_defines_it_as_instance_member_function; + } + + error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, typeToString(baseType), symbolToString(base), typeToString(type)); + } + } + + for (const [errorNode, memberInfo] of notImplementedInfo) { + if (length(memberInfo.missedProperties) === 1) { + if (isClassExpression(errorNode)) { + error(errorNode, Diagnostics.Non_abstract_class_expression_does_not_implement_inherited_abstract_member_0_from_class_1, first(memberInfo.missedProperties), memberInfo.baseTypeName); + } + else { + error(errorNode, Diagnostics.Non_abstract_class_0_does_not_implement_inherited_abstract_member_1_from_class_2, memberInfo.typeName, first(memberInfo.missedProperties), memberInfo.baseTypeName); + } + } + else if (length(memberInfo.missedProperties) > 5) { + const missedProperties = map(memberInfo.missedProperties.slice(0, 4), prop => `'${prop}'`).join(", "); + const remainingMissedProperties = length(memberInfo.missedProperties) - 4; + if (isClassExpression(errorNode)) { + error(errorNode, Diagnostics.Non_abstract_class_expression_is_missing_implementations_for_the_following_members_of_0_Colon_1_and_2_more, memberInfo.baseTypeName, missedProperties, remainingMissedProperties); + } + else { + error(errorNode, Diagnostics.Non_abstract_class_0_is_missing_implementations_for_the_following_members_of_1_Colon_2_and_3_more, memberInfo.typeName, memberInfo.baseTypeName, missedProperties, remainingMissedProperties); + } + } + else { + const missedProperties = map(memberInfo.missedProperties, prop => `'${prop}'`).join(", "); + if (isClassExpression(errorNode)) { + error(errorNode, Diagnostics.Non_abstract_class_expression_is_missing_implementations_for_the_following_members_of_0_Colon_1, memberInfo.baseTypeName, missedProperties); + } + else { + error(errorNode, Diagnostics.Non_abstract_class_0_is_missing_implementations_for_the_following_members_of_1_Colon_2, memberInfo.typeName, memberInfo.baseTypeName, missedProperties); + } + } + } + } + + function isPropertyAbstractOrInterface(declaration: Declaration, baseDeclarationFlags: ModifierFlags) { + return baseDeclarationFlags & ModifierFlags.Abstract && (!isPropertyDeclaration(declaration) || !declaration.initializer) + || isInterfaceDeclaration(declaration.parent); + } + + function getNonInheritedProperties(type: InterfaceType, baseTypes: BaseType[], properties: Symbol[]) { + if (!length(baseTypes)) { + return properties; + } + const seen = new Map<__String, Symbol>(); + forEach(properties, p => { + seen.set(p.escapedName, p); + }); + + for (const base of baseTypes) { + const properties = getPropertiesOfType(getTypeWithThisArgument(base, type.thisType)); + for (const prop of properties) { + const existing = seen.get(prop.escapedName); + if (existing && prop.parent === existing.parent) { + seen.delete(prop.escapedName); + } + } + } + + return arrayFrom(seen.values()); + } + + function checkInheritedPropertiesAreIdentical(type: InterfaceType, typeNode: Node): boolean { + const baseTypes = getBaseTypes(type); + if (baseTypes.length < 2) { + return true; + } + + interface InheritanceInfoMap { + prop: Symbol; + containingType: Type; + } + const seen = new Map<__String, InheritanceInfoMap>(); + forEach(resolveDeclaredMembers(type).declaredProperties, p => { + seen.set(p.escapedName, { prop: p, containingType: type }); + }); + let ok = true; + + for (const base of baseTypes) { + const properties = getPropertiesOfType(getTypeWithThisArgument(base, type.thisType)); + for (const prop of properties) { + const existing = seen.get(prop.escapedName); + if (!existing) { + seen.set(prop.escapedName, { prop, containingType: base }); + } + else { + const isInheritedProperty = existing.containingType !== type; + if (isInheritedProperty && !isPropertyIdenticalTo(existing.prop, prop)) { + ok = false; + + const typeName1 = typeToString(existing.containingType); + const typeName2 = typeToString(base); + + let errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Named_property_0_of_types_1_and_2_are_not_identical, symbolToString(prop), typeName1, typeName2); + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Interface_0_cannot_simultaneously_extend_types_1_and_2, typeToString(type), typeName1, typeName2); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(typeNode), typeNode, errorInfo)); + } + } + } + } + + return ok; + } + + function checkPropertyInitialization(node: ClassLikeDeclaration) { + if (!strictNullChecks || !strictPropertyInitialization || node.flags & NodeFlags.Ambient) { + return; + } + const constructor = findConstructorDeclaration(node); + for (const member of node.members) { + if (getEffectiveModifierFlags(member) & ModifierFlags.Ambient) { + continue; + } + if (!isStatic(member) && isPropertyWithoutInitializer(member)) { + const propName = (member as PropertyDeclaration).name; + if (isIdentifier(propName) || isPrivateIdentifier(propName) || isComputedPropertyName(propName)) { + const type = getTypeOfSymbol(getSymbolOfDeclaration(member)); + if (!(type.flags & TypeFlags.AnyOrUnknown || containsUndefinedType(type))) { + if (!constructor || !isPropertyInitializedInConstructor(propName, type, constructor)) { + error(member.name, Diagnostics.Property_0_has_no_initializer_and_is_not_definitely_assigned_in_the_constructor, declarationNameToString(propName)); + } + } + } + } + } + } + + function isPropertyWithoutInitializer(node: Node) { + return node.kind === SyntaxKind.PropertyDeclaration && + !hasAbstractModifier(node) && + !(node as PropertyDeclaration).exclamationToken && + !(node as PropertyDeclaration).initializer; + } + + function isPropertyInitializedInStaticBlocks(propName: Identifier | PrivateIdentifier, propType: Type, staticBlocks: readonly ClassStaticBlockDeclaration[], startPos: number, endPos: number) { + for (const staticBlock of staticBlocks) { + // static block must be within the provided range as they are evaluated in document order (unlike constructors) + if (staticBlock.pos >= startPos && staticBlock.pos <= endPos) { + const reference = factory.createPropertyAccessExpression(factory.createThis(), propName); + setParent(reference.expression, reference); + setParent(reference, staticBlock); + reference.flowNode = staticBlock.returnFlowNode; + const flowType = getFlowTypeOfReference(reference, propType, getOptionalType(propType)); + if (!containsUndefinedType(flowType)) { + return true; + } + } + } + return false; + } + + function isPropertyInitializedInConstructor(propName: Identifier | PrivateIdentifier | ComputedPropertyName, propType: Type, constructor: ConstructorDeclaration) { + const reference = isComputedPropertyName(propName) + ? factory.createElementAccessExpression(factory.createThis(), propName.expression) + : factory.createPropertyAccessExpression(factory.createThis(), propName); + setParent(reference.expression, reference); + setParent(reference, constructor); + reference.flowNode = constructor.returnFlowNode; + const flowType = getFlowTypeOfReference(reference, propType, getOptionalType(propType)); + return !containsUndefinedType(flowType); + } + + function checkInterfaceDeclaration(node: InterfaceDeclaration) { + // Grammar checking + if (!checkGrammarModifiers(node)) checkGrammarInterfaceDeclaration(node); + + checkTypeParameters(node.typeParameters); + addLazyDiagnostic(() => { + checkTypeNameIsReserved(node.name, Diagnostics.Interface_name_cannot_be_0); + + checkExportsOnMergedDeclarations(node); + const symbol = getSymbolOfDeclaration(node); + checkTypeParameterListsIdentical(symbol); + + // Only check this symbol once + const firstInterfaceDecl = getDeclarationOfKind(symbol, SyntaxKind.InterfaceDeclaration); + if (node === firstInterfaceDecl) { + const type = getDeclaredTypeOfSymbol(symbol) as InterfaceType; + const typeWithThis = getTypeWithThisArgument(type); + // run subsequent checks only if first set succeeded + if (checkInheritedPropertiesAreIdentical(type, node.name)) { + for (const baseType of getBaseTypes(type)) { + checkTypeAssignableTo(typeWithThis, getTypeWithThisArgument(baseType, type.thisType), node.name, Diagnostics.Interface_0_incorrectly_extends_interface_1); + } + checkIndexConstraints(type, symbol); + } + } + checkObjectTypeForDuplicateDeclarations(node); + }); + forEach(getInterfaceBaseTypeNodes(node), heritageElement => { + if (!isEntityNameExpression(heritageElement.expression) || isOptionalChain(heritageElement.expression)) { + error(heritageElement.expression, Diagnostics.An_interface_can_only_extend_an_identifier_Slashqualified_name_with_optional_type_arguments); + } + checkTypeReferenceNode(heritageElement); + }); + + forEach(node.members, checkSourceElement); + + addLazyDiagnostic(() => { + checkTypeForDuplicateIndexSignatures(node); + registerForUnusedIdentifiersCheck(node); + }); + } + + function checkTypeAliasDeclaration(node: TypeAliasDeclaration) { + // Grammar checking + checkGrammarModifiers(node); + checkTypeNameIsReserved(node.name, Diagnostics.Type_alias_name_cannot_be_0); + checkExportsOnMergedDeclarations(node); + checkTypeParameters(node.typeParameters); + if (node.type.kind === SyntaxKind.IntrinsicKeyword) { + if (!intrinsicTypeKinds.has(node.name.escapedText as string) || length(node.typeParameters) !== 1) { + error(node.type, Diagnostics.The_intrinsic_keyword_can_only_be_used_to_declare_compiler_provided_intrinsic_types); + } + } + else { + checkSourceElement(node.type); + registerForUnusedIdentifiersCheck(node); + } + } + + function computeEnumMemberValues(node: EnumDeclaration) { + const nodeLinks = getNodeLinks(node); + if (!(nodeLinks.flags & NodeCheckFlags.EnumValuesComputed)) { + nodeLinks.flags |= NodeCheckFlags.EnumValuesComputed; + let autoValue: number | undefined = 0; + let previous: EnumMember | undefined; + for (const member of node.members) { + const result = computeEnumMemberValue(member, autoValue, previous); + getNodeLinks(member).enumMemberValue = result; + autoValue = typeof result.value === "number" ? result.value + 1 : undefined; + previous = member; + } + } + } + + function computeEnumMemberValue(member: EnumMember, autoValue: number | undefined, previous: EnumMember | undefined): EvaluatorResult { + if (isComputedNonLiteralName(member.name)) { + error(member.name, Diagnostics.Computed_property_names_are_not_allowed_in_enums); + } + else { + const text = getTextOfPropertyName(member.name); + if (isNumericLiteralName(text) && !isInfinityOrNaNString(text)) { + error(member.name, Diagnostics.An_enum_member_cannot_have_a_numeric_name); + } + } + if (member.initializer) { + return computeConstantEnumMemberValue(member); + } + // In ambient non-const numeric enum declarations, enum members without initializers are + // considered computed members (as opposed to having auto-incremented values). + if (member.parent.flags & NodeFlags.Ambient && !isEnumConst(member.parent)) { + return evaluatorResult(/*value*/ undefined); + } + // If the member declaration specifies no value, the member is considered a constant enum member. + // If the member is the first member in the enum declaration, it is assigned the value zero. + // Otherwise, it is assigned the value of the immediately preceding member plus one, and an error + // occurs if the immediately preceding member is not a constant enum member. + if (autoValue === undefined) { + error(member.name, Diagnostics.Enum_member_must_have_initializer); + return evaluatorResult(/*value*/ undefined); + } + if (getIsolatedModules(compilerOptions) && previous?.initializer) { + const prevValue = getEnumMemberValue(previous); + if (!(typeof prevValue.value === "number" && !prevValue.resolvedOtherFiles)) { + error( + member.name, + Diagnostics.Enum_member_following_a_non_literal_numeric_member_must_have_an_initializer_when_isolatedModules_is_enabled, + ); + } + } + return evaluatorResult(autoValue); + } + + function computeConstantEnumMemberValue(member: EnumMember): EvaluatorResult { + const isConstEnum = isEnumConst(member.parent); + const initializer = member.initializer!; + const result = evaluate(initializer, member); + if (result.value !== undefined) { + if (isConstEnum && typeof result.value === "number" && !isFinite(result.value)) { + error( + initializer, + isNaN(result.value) ? + Diagnostics.const_enum_member_initializer_was_evaluated_to_disallowed_value_NaN : + Diagnostics.const_enum_member_initializer_was_evaluated_to_a_non_finite_value, + ); + } + else if (getIsolatedModules(compilerOptions) && typeof result.value === "string" && !result.isSyntacticallyString) { + error( + initializer, + Diagnostics._0_has_a_string_type_but_must_have_syntactically_recognizable_string_syntax_when_isolatedModules_is_enabled, + `${idText(member.parent.name)}.${getTextOfPropertyName(member.name)}`, + ); + } + } + else if (isConstEnum) { + error(initializer, Diagnostics.const_enum_member_initializers_must_be_constant_expressions); + } + else if (member.parent.flags & NodeFlags.Ambient) { + error(initializer, Diagnostics.In_ambient_enum_declarations_member_initializer_must_be_constant_expression); + } + else { + checkTypeAssignableTo(checkExpression(initializer), numberType, initializer, Diagnostics.Type_0_is_not_assignable_to_type_1_as_required_for_computed_enum_member_values); + } + return result; + } + + function evaluateEntityNameExpression(expr: EntityNameExpression, location?: Declaration) { + const symbol = resolveEntityName(expr, SymbolFlags.Value, /*ignoreErrors*/ true); + if (!symbol) return evaluatorResult(/*value*/ undefined); + + if (expr.kind === SyntaxKind.Identifier) { + const identifier = expr; + if (isInfinityOrNaNString(identifier.escapedText) && (symbol === getGlobalSymbol(identifier.escapedText, SymbolFlags.Value, /*diagnostic*/ undefined))) { + // Technically we resolved a global lib file here, but the decision to treat this as numeric + // is more predicated on the fact that the single-file resolution *didn't* resolve to a + // different meaning of `Infinity` or `NaN`. Transpilers handle this no problem. + return evaluatorResult(+(identifier.escapedText), /*isSyntacticallyString*/ false); + } + } + + if (symbol.flags & SymbolFlags.EnumMember) { + return location ? evaluateEnumMember(expr, symbol, location) : getEnumMemberValue(symbol.valueDeclaration as EnumMember); + } + if (isConstantVariable(symbol)) { + const declaration = symbol.valueDeclaration; + if (declaration && isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && (!location || declaration !== location && isBlockScopedNameDeclaredBeforeUse(declaration, location))) { + const result = evaluate(declaration.initializer, declaration); + if (location && getSourceFileOfNode(location) !== getSourceFileOfNode(declaration)) { + return evaluatorResult( + result.value, + /*isSyntacticallyString*/ false, + /*resolvedOtherFiles*/ true, + /*hasExternalReferences*/ true, + ); + } + return evaluatorResult(result.value, result.isSyntacticallyString, result.resolvedOtherFiles, /*hasExternalReferences*/ true); + } + } + return evaluatorResult(/*value*/ undefined); + } + + function evaluateElementAccessExpression(expr: ElementAccessExpression, location?: Declaration) { + const root = expr.expression; + if (isEntityNameExpression(root) && isStringLiteralLike(expr.argumentExpression)) { + const rootSymbol = resolveEntityName(root, SymbolFlags.Value, /*ignoreErrors*/ true); + if (rootSymbol && rootSymbol.flags & SymbolFlags.Enum) { + const name = escapeLeadingUnderscores(expr.argumentExpression.text); + const member = rootSymbol.exports!.get(name); + if (member) { + Debug.assert(getSourceFileOfNode(member.valueDeclaration) === getSourceFileOfNode(rootSymbol.valueDeclaration)); + return location ? evaluateEnumMember(expr, member, location) : getEnumMemberValue(member.valueDeclaration as EnumMember); + } + } + } + return evaluatorResult(/*value*/ undefined); + } + + function evaluateEnumMember(expr: Expression, symbol: Symbol, location: Declaration) { + const declaration = symbol.valueDeclaration; + if (!declaration || declaration === location) { + error(expr, Diagnostics.Property_0_is_used_before_being_assigned, symbolToString(symbol)); + return evaluatorResult(/*value*/ undefined); + } + if (!isBlockScopedNameDeclaredBeforeUse(declaration, location)) { + error(expr, Diagnostics.A_member_initializer_in_a_enum_declaration_cannot_reference_members_declared_after_it_including_members_defined_in_other_enums); + return evaluatorResult(/*value*/ 0); + } + const value = getEnumMemberValue(declaration as EnumMember); + if (location.parent !== declaration.parent) { + return evaluatorResult(value.value, value.isSyntacticallyString, value.resolvedOtherFiles, /*hasExternalReferences*/ true); + } + return value; + } + + function checkEnumDeclaration(node: EnumDeclaration) { + addLazyDiagnostic(() => checkEnumDeclarationWorker(node)); + } + + function checkEnumDeclarationWorker(node: EnumDeclaration) { + // Grammar checking + checkGrammarModifiers(node); + + checkCollisionsForDeclarationName(node, node.name); + checkExportsOnMergedDeclarations(node); + node.members.forEach(checkEnumMember); + + computeEnumMemberValues(node); + + // Spec 2014 - Section 9.3: + // It isn't possible for one enum declaration to continue the automatic numbering sequence of another, + // and when an enum type has multiple declarations, only one declaration is permitted to omit a value + // for the first member. + // + // Only perform this check once per symbol + const enumSymbol = getSymbolOfDeclaration(node); + const firstDeclaration = getDeclarationOfKind(enumSymbol, node.kind); + if (node === firstDeclaration) { + if (enumSymbol.declarations && enumSymbol.declarations.length > 1) { + const enumIsConst = isEnumConst(node); + // check that const is placed\omitted on all enum declarations + forEach(enumSymbol.declarations, decl => { + if (isEnumDeclaration(decl) && isEnumConst(decl) !== enumIsConst) { + error(getNameOfDeclaration(decl), Diagnostics.Enum_declarations_must_all_be_const_or_non_const); + } + }); + } + + let seenEnumMissingInitialInitializer = false; + forEach(enumSymbol.declarations, declaration => { + // return true if we hit a violation of the rule, false otherwise + if (declaration.kind !== SyntaxKind.EnumDeclaration) { + return false; + } + + const enumDeclaration = declaration as EnumDeclaration; + if (!enumDeclaration.members.length) { + return false; + } + + const firstEnumMember = enumDeclaration.members[0]; + if (!firstEnumMember.initializer) { + if (seenEnumMissingInitialInitializer) { + error(firstEnumMember.name, Diagnostics.In_an_enum_with_multiple_declarations_only_one_declaration_can_omit_an_initializer_for_its_first_enum_element); + } + else { + seenEnumMissingInitialInitializer = true; + } + } + }); + } + } + + function checkEnumMember(node: EnumMember) { + if (isPrivateIdentifier(node.name)) { + error(node, Diagnostics.An_enum_member_cannot_be_named_with_a_private_identifier); + } + if (node.initializer) { + checkExpression(node.initializer); + } + } + + function getFirstNonAmbientClassOrFunctionDeclaration(symbol: Symbol): Declaration | undefined { + const declarations = symbol.declarations; + if (declarations) { + for (const declaration of declarations) { + if ( + (declaration.kind === SyntaxKind.ClassDeclaration || + (declaration.kind === SyntaxKind.FunctionDeclaration && nodeIsPresent((declaration as FunctionLikeDeclaration).body))) && + !(declaration.flags & NodeFlags.Ambient) + ) { + return declaration; + } + } + } + return undefined; + } + + function inSameLexicalScope(node1: Node, node2: Node) { + const container1 = getEnclosingBlockScopeContainer(node1); + const container2 = getEnclosingBlockScopeContainer(node2); + if (isGlobalSourceFile(container1)) { + return isGlobalSourceFile(container2); + } + else if (isGlobalSourceFile(container2)) { + return false; + } + else { + return container1 === container2; + } + } + + function checkModuleDeclaration(node: ModuleDeclaration) { + if (node.body) { + checkSourceElement(node.body); + if (!isGlobalScopeAugmentation(node)) { + registerForUnusedIdentifiersCheck(node); + } + } + + addLazyDiagnostic(checkModuleDeclarationDiagnostics); + + function checkModuleDeclarationDiagnostics() { + // Grammar checking + const isGlobalAugmentation = isGlobalScopeAugmentation(node); + const inAmbientContext = node.flags & NodeFlags.Ambient; + if (isGlobalAugmentation && !inAmbientContext) { + error(node.name, Diagnostics.Augmentations_for_the_global_scope_should_have_declare_modifier_unless_they_appear_in_already_ambient_context); + } + + const isAmbientExternalModule: boolean = isAmbientModule(node); + const contextErrorMessage = isAmbientExternalModule + ? Diagnostics.An_ambient_module_declaration_is_only_allowed_at_the_top_level_in_a_file + : Diagnostics.A_namespace_declaration_is_only_allowed_at_the_top_level_of_a_namespace_or_module; + if (checkGrammarModuleElementContext(node, contextErrorMessage)) { + // If we hit a module declaration in an illegal context, just bail out to avoid cascading errors. + return; + } + + if (!checkGrammarModifiers(node)) { + if (!inAmbientContext && node.name.kind === SyntaxKind.StringLiteral) { + grammarErrorOnNode(node.name, Diagnostics.Only_ambient_modules_can_use_quoted_names); + } + } + + if (isIdentifier(node.name)) { + checkCollisionsForDeclarationName(node, node.name); + } + + checkExportsOnMergedDeclarations(node); + const symbol = getSymbolOfDeclaration(node); + + // The following checks only apply on a non-ambient instantiated module declaration. + if ( + symbol.flags & SymbolFlags.ValueModule + && !inAmbientContext + && isInstantiatedModule(node, shouldPreserveConstEnums(compilerOptions)) + ) { + if (getIsolatedModules(compilerOptions) && !getSourceFileOfNode(node).externalModuleIndicator) { + // This could be loosened a little if needed. The only problem we are trying to avoid is unqualified + // references to namespace members declared in other files. But use of namespaces is discouraged anyway, + // so for now we will just not allow them in scripts, which is the only place they can merge cross-file. + error(node.name, Diagnostics.Namespaces_are_not_allowed_in_global_script_files_when_0_is_enabled_If_this_file_is_not_intended_to_be_a_global_script_set_moduleDetection_to_force_or_add_an_empty_export_statement, isolatedModulesLikeFlagName); + } + if (symbol.declarations?.length! > 1) { + const firstNonAmbientClassOrFunc = getFirstNonAmbientClassOrFunctionDeclaration(symbol); + if (firstNonAmbientClassOrFunc) { + if (getSourceFileOfNode(node) !== getSourceFileOfNode(firstNonAmbientClassOrFunc)) { + error(node.name, Diagnostics.A_namespace_declaration_cannot_be_in_a_different_file_from_a_class_or_function_with_which_it_is_merged); + } + else if (node.pos < firstNonAmbientClassOrFunc.pos) { + error(node.name, Diagnostics.A_namespace_declaration_cannot_be_located_prior_to_a_class_or_function_with_which_it_is_merged); + } + } + + // if the module merges with a class declaration in the same lexical scope, + // we need to track this to ensure the correct emit. + const mergedClass = getDeclarationOfKind(symbol, SyntaxKind.ClassDeclaration); + if ( + mergedClass && + inSameLexicalScope(node, mergedClass) + ) { + getNodeLinks(node).flags |= NodeCheckFlags.LexicalModuleMergesWithClass; + } + } + if ( + compilerOptions.verbatimModuleSyntax && + node.parent.kind === SyntaxKind.SourceFile && + (moduleKind === ModuleKind.CommonJS || node.parent.impliedNodeFormat === ModuleKind.CommonJS) + ) { + const exportModifier = node.modifiers?.find(m => m.kind === SyntaxKind.ExportKeyword); + if (exportModifier) { + error(exportModifier, Diagnostics.A_top_level_export_modifier_cannot_be_used_on_value_declarations_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + } + } + + if (isAmbientExternalModule) { + if (isExternalModuleAugmentation(node)) { + // body of the augmentation should be checked for consistency only if augmentation was applied to its target (either global scope or module) + // otherwise we'll be swamped in cascading errors. + // We can detect if augmentation was applied using following rules: + // - augmentation for a global scope is always applied + // - augmentation for some external module is applied if symbol for augmentation is merged (it was combined with target module). + const checkBody = isGlobalAugmentation || (getSymbolOfDeclaration(node).flags & SymbolFlags.Transient); + if (checkBody && node.body) { + for (const statement of node.body.statements) { + checkModuleAugmentationElement(statement, isGlobalAugmentation); + } + } + } + else if (isGlobalSourceFile(node.parent)) { + if (isGlobalAugmentation) { + error(node.name, Diagnostics.Augmentations_for_the_global_scope_can_only_be_directly_nested_in_external_modules_or_ambient_module_declarations); + } + else if (isExternalModuleNameRelative(getTextOfIdentifierOrLiteral(node.name))) { + error(node.name, Diagnostics.Ambient_module_declaration_cannot_specify_relative_module_name); + } + } + else { + if (isGlobalAugmentation) { + error(node.name, Diagnostics.Augmentations_for_the_global_scope_can_only_be_directly_nested_in_external_modules_or_ambient_module_declarations); + } + else { + // Node is not an augmentation and is not located on the script level. + // This means that this is declaration of ambient module that is located in other module or namespace which is prohibited. + error(node.name, Diagnostics.Ambient_modules_cannot_be_nested_in_other_modules_or_namespaces); + } + } + } + } + } + + function checkModuleAugmentationElement(node: Node, isGlobalAugmentation: boolean): void { + switch (node.kind) { + case SyntaxKind.VariableStatement: + // error each individual name in variable statement instead of marking the entire variable statement + for (const decl of (node as VariableStatement).declarationList.declarations) { + checkModuleAugmentationElement(decl, isGlobalAugmentation); + } + break; + case SyntaxKind.ExportAssignment: + case SyntaxKind.ExportDeclaration: + grammarErrorOnFirstToken(node, Diagnostics.Exports_and_export_assignments_are_not_permitted_in_module_augmentations); + break; + case SyntaxKind.ImportEqualsDeclaration: + case SyntaxKind.ImportDeclaration: + grammarErrorOnFirstToken(node, Diagnostics.Imports_are_not_permitted_in_module_augmentations_Consider_moving_them_to_the_enclosing_external_module); + break; + case SyntaxKind.BindingElement: + case SyntaxKind.VariableDeclaration: + const name = (node as VariableDeclaration | BindingElement).name; + if (isBindingPattern(name)) { + for (const el of name.elements) { + // mark individual names in binding pattern + checkModuleAugmentationElement(el, isGlobalAugmentation); + } + break; + } + // falls through + case SyntaxKind.ClassDeclaration: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.TypeAliasDeclaration: + if (isGlobalAugmentation) { + return; + } + break; + } + } + + function getFirstNonModuleExportsIdentifier(node: EntityNameOrEntityNameExpression): Identifier { + switch (node.kind) { + case SyntaxKind.Identifier: + return node; + case SyntaxKind.QualifiedName: + do { + node = node.left; + } + while (node.kind !== SyntaxKind.Identifier); + return node; + case SyntaxKind.PropertyAccessExpression: + do { + if (isModuleExportsAccessExpression(node.expression) && !isPrivateIdentifier(node.name)) { + return node.name; + } + node = node.expression; + } + while (node.kind !== SyntaxKind.Identifier); + return node; + } + } + + function checkExternalImportOrExportDeclaration(node: ImportDeclaration | ImportEqualsDeclaration | ExportDeclaration): boolean { + const moduleName = getExternalModuleName(node); + if (!moduleName || nodeIsMissing(moduleName)) { + // Should be a parse error. + return false; + } + if (!isStringLiteral(moduleName)) { + error(moduleName, Diagnostics.String_literal_expected); + return false; + } + const inAmbientExternalModule = node.parent.kind === SyntaxKind.ModuleBlock && isAmbientModule(node.parent.parent); + if (node.parent.kind !== SyntaxKind.SourceFile && !inAmbientExternalModule) { + error( + moduleName, + node.kind === SyntaxKind.ExportDeclaration ? + Diagnostics.Export_declarations_are_not_permitted_in_a_namespace : + Diagnostics.Import_declarations_in_a_namespace_cannot_reference_a_module, + ); + return false; + } + if (inAmbientExternalModule && isExternalModuleNameRelative(moduleName.text)) { + // we have already reported errors on top level imports/exports in external module augmentations in checkModuleDeclaration + // no need to do this again. + if (!isTopLevelInExternalModuleAugmentation(node)) { + // TypeScript 1.0 spec (April 2013): 12.1.6 + // An ExternalImportDeclaration in an AmbientExternalModuleDeclaration may reference + // other external modules only through top - level external module names. + // Relative external module names are not permitted. + error(node, Diagnostics.Import_or_export_declaration_in_an_ambient_module_declaration_cannot_reference_module_through_relative_module_name); + return false; + } + } + if (!isImportEqualsDeclaration(node) && node.attributes) { + const diagnostic = node.attributes.token === SyntaxKind.WithKeyword ? Diagnostics.Import_attribute_values_must_be_string_literal_expressions : Diagnostics.Import_assertion_values_must_be_string_literal_expressions; + let hasError = false; + for (const attr of node.attributes.elements) { + if (!isStringLiteral(attr.value)) { + hasError = true; + error(attr.value, diagnostic); + } + } + return !hasError; + } + return true; + } + + function checkModuleExportName(name: ModuleExportName | undefined, allowStringLiteral = true) { + if (name === undefined || name.kind !== SyntaxKind.StringLiteral) { + return; + } + if (!allowStringLiteral) { + grammarErrorOnNode(name, Diagnostics.Identifier_expected); + } + else if (moduleKind === ModuleKind.ES2015 || moduleKind === ModuleKind.ES2020) { + grammarErrorOnNode(name, Diagnostics.String_literal_import_and_export_names_are_not_supported_when_the_module_flag_is_set_to_es2015_or_es2020); + } + } + + function checkAliasSymbol(node: AliasDeclarationNode) { + let symbol = getSymbolOfDeclaration(node); + const target = resolveAlias(symbol); + + if (target !== unknownSymbol) { + // For external modules, `symbol` represents the local symbol for an alias. + // This local symbol will merge any other local declarations (excluding other aliases) + // and symbol.flags will contains combined representation for all merged declaration. + // Based on symbol.flags we can compute a set of excluded meanings (meaning that resolved alias should not have, + // otherwise it will conflict with some local declaration). Note that in addition to normal flags we include matching SymbolFlags.Export* + // in order to prevent collisions with declarations that were exported from the current module (they still contribute to local names). + symbol = getMergedSymbol(symbol.exportSymbol || symbol); + + // A type-only import/export will already have a grammar error in a JS file, so no need to issue more errors within + if (isInJSFile(node) && !(target.flags & SymbolFlags.Value) && !isTypeOnlyImportOrExportDeclaration(node)) { + const errorNode = isImportOrExportSpecifier(node) ? node.propertyName || node.name : + isNamedDeclaration(node) ? node.name : + node; + + Debug.assert(node.kind !== SyntaxKind.NamespaceExport); + if (node.kind === SyntaxKind.ExportSpecifier) { + const diag = error(errorNode, Diagnostics.Types_cannot_appear_in_export_declarations_in_JavaScript_files); + const alreadyExportedSymbol = getSourceFileOfNode(node).symbol?.exports?.get(moduleExportNameTextEscaped(node.propertyName || node.name)); + if (alreadyExportedSymbol === target) { + const exportingDeclaration = alreadyExportedSymbol.declarations?.find(isJSDocNode); + if (exportingDeclaration) { + addRelatedInfo( + diag, + createDiagnosticForNode( + exportingDeclaration, + Diagnostics._0_is_automatically_exported_here, + unescapeLeadingUnderscores(alreadyExportedSymbol.escapedName), + ), + ); + } + } + } + else { + Debug.assert(node.kind !== SyntaxKind.VariableDeclaration); + const importDeclaration = findAncestor(node, or(isImportDeclaration, isImportEqualsDeclaration)); + const moduleSpecifier = (importDeclaration && tryGetModuleSpecifierFromDeclaration(importDeclaration)?.text) ?? "..."; + const importedIdentifier = unescapeLeadingUnderscores(isIdentifier(errorNode) ? errorNode.escapedText : symbol.escapedName); + error( + errorNode, + Diagnostics._0_is_a_type_and_cannot_be_imported_in_JavaScript_files_Use_1_in_a_JSDoc_type_annotation, + importedIdentifier, + `import("${moduleSpecifier}").${importedIdentifier}`, + ); + } + return; + } + + const targetFlags = getSymbolFlags(target); + const excludedMeanings = (symbol.flags & (SymbolFlags.Value | SymbolFlags.ExportValue) ? SymbolFlags.Value : 0) | + (symbol.flags & SymbolFlags.Type ? SymbolFlags.Type : 0) | + (symbol.flags & SymbolFlags.Namespace ? SymbolFlags.Namespace : 0); + if (targetFlags & excludedMeanings) { + const message = node.kind === SyntaxKind.ExportSpecifier ? + Diagnostics.Export_declaration_conflicts_with_exported_declaration_of_0 : + Diagnostics.Import_declaration_conflicts_with_local_declaration_of_0; + error(node, message, symbolToString(symbol)); + } + else if (node.kind !== SyntaxKind.ExportSpecifier) { + // Look at 'compilerOptions.isolatedModules' and not 'getIsolatedModules(...)' (which considers 'verbatimModuleSyntax') + // here because 'verbatimModuleSyntax' will already have an error for importing a type without 'import type'. + const appearsValueyToTranspiler = compilerOptions.isolatedModules && !findAncestor(node, isTypeOnlyImportOrExportDeclaration); + if (appearsValueyToTranspiler && symbol.flags & (SymbolFlags.Value | SymbolFlags.ExportValue)) { + error( + node, + Diagnostics.Import_0_conflicts_with_local_value_so_must_be_declared_with_a_type_only_import_when_isolatedModules_is_enabled, + symbolToString(symbol), + isolatedModulesLikeFlagName, + ); + } + } + + if ( + getIsolatedModules(compilerOptions) + && !isTypeOnlyImportOrExportDeclaration(node) + && !(node.flags & NodeFlags.Ambient) + ) { + const typeOnlyAlias = getTypeOnlyAliasDeclaration(symbol); + const isType = !(targetFlags & SymbolFlags.Value); + if (isType || typeOnlyAlias) { + switch (node.kind) { + case SyntaxKind.ImportClause: + case SyntaxKind.ImportSpecifier: + case SyntaxKind.ImportEqualsDeclaration: { + if (compilerOptions.verbatimModuleSyntax) { + Debug.assertIsDefined(node.name, "An ImportClause with a symbol should have a name"); + const message = compilerOptions.verbatimModuleSyntax && isInternalModuleImportEqualsDeclaration(node) + ? Diagnostics.An_import_alias_cannot_resolve_to_a_type_or_type_only_declaration_when_verbatimModuleSyntax_is_enabled + : isType + ? Diagnostics._0_is_a_type_and_must_be_imported_using_a_type_only_import_when_verbatimModuleSyntax_is_enabled + : Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_imported_using_a_type_only_import_when_verbatimModuleSyntax_is_enabled; + const name = moduleExportNameTextUnescaped(node.kind === SyntaxKind.ImportSpecifier ? node.propertyName || node.name : node.name); + addTypeOnlyDeclarationRelatedInfo( + error(node, message, name), + isType ? undefined : typeOnlyAlias, + name, + ); + } + if (isType && node.kind === SyntaxKind.ImportEqualsDeclaration && hasEffectiveModifier(node, ModifierFlags.Export)) { + error(node, Diagnostics.Cannot_use_export_import_on_a_type_or_type_only_namespace_when_0_is_enabled, isolatedModulesLikeFlagName); + } + break; + } + case SyntaxKind.ExportSpecifier: { + // Don't allow re-exporting an export that will be elided when `--isolatedModules` is set. + // The exception is that `import type { A } from './a'; export { A }` is allowed + // because single-file analysis can determine that the export should be dropped. + if (compilerOptions.verbatimModuleSyntax || getSourceFileOfNode(typeOnlyAlias) !== getSourceFileOfNode(node)) { + const name = moduleExportNameTextUnescaped(node.propertyName || node.name); + const diagnostic = isType + ? error(node, Diagnostics.Re_exporting_a_type_when_0_is_enabled_requires_using_export_type, isolatedModulesLikeFlagName) + : error(node, Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_re_exported_using_a_type_only_re_export_when_1_is_enabled, name, isolatedModulesLikeFlagName); + addTypeOnlyDeclarationRelatedInfo(diagnostic, isType ? undefined : typeOnlyAlias, name); + break; + } + } + } + } + + if ( + compilerOptions.verbatimModuleSyntax && + node.kind !== SyntaxKind.ImportEqualsDeclaration && + !isInJSFile(node) && + (moduleKind === ModuleKind.CommonJS || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) + ) { + error(node, Diagnostics.ESM_syntax_is_not_allowed_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + } + + if (isImportSpecifier(node)) { + const targetSymbol = resolveAliasWithDeprecationCheck(symbol, node); + if (isDeprecatedSymbol(targetSymbol) && targetSymbol.declarations) { + addDeprecatedSuggestion(node, targetSymbol.declarations, targetSymbol.escapedName as string); + } + } + } + } + + function resolveAliasWithDeprecationCheck(symbol: Symbol, location: Node) { + if (!(symbol.flags & SymbolFlags.Alias) || isDeprecatedSymbol(symbol) || !getDeclarationOfAliasSymbol(symbol)) { + return symbol; + } + + const targetSymbol = resolveAlias(symbol); + if (targetSymbol === unknownSymbol) return targetSymbol; + + while (symbol.flags & SymbolFlags.Alias) { + const target = getImmediateAliasedSymbol(symbol); + if (target) { + if (target === targetSymbol) break; + if (target.declarations && length(target.declarations)) { + if (isDeprecatedSymbol(target)) { + addDeprecatedSuggestion(location, target.declarations, target.escapedName as string); + break; + } + else { + if (symbol === targetSymbol) break; + symbol = target; + } + } + } + else { + break; + } + } + return targetSymbol; + } + + function checkImportBinding(node: ImportEqualsDeclaration | ImportClause | NamespaceImport | ImportSpecifier) { + checkCollisionsForDeclarationName(node, node.name); + checkAliasSymbol(node); + if (node.kind === SyntaxKind.ImportSpecifier) { + checkModuleExportName(node.propertyName); + if ( + moduleExportNameIsDefault(node.propertyName || node.name) && + getESModuleInterop(compilerOptions) && + moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) + ) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportDefault); + } + } + } + + function checkImportAttributes(declaration: ImportDeclaration | ExportDeclaration | JSDocImportTag) { + const node = declaration.attributes; + if (node) { + const importAttributesType = getGlobalImportAttributesType(/*reportErrors*/ true); + if (importAttributesType !== emptyObjectType) { + checkTypeAssignableTo(getTypeFromImportAttributes(node), getNullableType(importAttributesType, TypeFlags.Undefined), node); + } + + const validForTypeAttributes = isExclusivelyTypeOnlyImportOrExport(declaration); + const override = getResolutionModeOverride(node, validForTypeAttributes ? grammarErrorOnNode : undefined); + const isImportAttributes = declaration.attributes.token === SyntaxKind.WithKeyword; + if (validForTypeAttributes && override) { + return; // Other grammar checks do not apply to type-only imports with resolution mode assertions + } + + const mode = (moduleKind === ModuleKind.NodeNext) && declaration.moduleSpecifier && getUsageModeForExpression(declaration.moduleSpecifier); + if (mode !== ModuleKind.ESNext && moduleKind !== ModuleKind.ESNext && moduleKind !== ModuleKind.Preserve) { + const message = isImportAttributes + ? moduleKind === ModuleKind.NodeNext + ? Diagnostics.Import_attributes_are_not_allowed_on_statements_that_compile_to_CommonJS_require_calls + : Diagnostics.Import_attributes_are_only_supported_when_the_module_option_is_set_to_esnext_nodenext_or_preserve + : moduleKind === ModuleKind.NodeNext + ? Diagnostics.Import_assertions_are_not_allowed_on_statements_that_compile_to_CommonJS_require_calls + : Diagnostics.Import_assertions_are_only_supported_when_the_module_option_is_set_to_esnext_nodenext_or_preserve; + return grammarErrorOnNode(node, message); + } + + const isTypeOnly = isJSDocImportTag(declaration) || (isImportDeclaration(declaration) ? declaration.importClause?.isTypeOnly : declaration.isTypeOnly); + if (isTypeOnly) { + return grammarErrorOnNode(node, isImportAttributes ? Diagnostics.Import_attributes_cannot_be_used_with_type_only_imports_or_exports : Diagnostics.Import_assertions_cannot_be_used_with_type_only_imports_or_exports); + } + + if (override) { + return grammarErrorOnNode(node, Diagnostics.resolution_mode_can_only_be_set_for_type_only_imports); + } + } + } + + function checkImportAttribute(node: ImportAttribute) { + return getRegularTypeOfLiteralType(checkExpressionCached(node.value)); + } + + function checkImportDeclaration(node: ImportDeclaration) { + if (checkGrammarModuleElementContext(node, isInJSFile(node) ? Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_module : Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_namespace_or_module)) { + // If we hit an import declaration in an illegal context, just bail out to avoid cascading errors. + return; + } + if (!checkGrammarModifiers(node) && node.modifiers) { + grammarErrorOnFirstToken(node, Diagnostics.An_import_declaration_cannot_have_modifiers); + } + if (checkExternalImportOrExportDeclaration(node)) { + const importClause = node.importClause; + if (importClause && !checkGrammarImportClause(importClause)) { + if (importClause.name) { + checkImportBinding(importClause); + } + if (importClause.namedBindings) { + if (importClause.namedBindings.kind === SyntaxKind.NamespaceImport) { + checkImportBinding(importClause.namedBindings); + if (moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) && getESModuleInterop(compilerOptions)) { + // import * as ns from "foo"; + checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportStar); + } + } + else { + const moduleExisted = resolveExternalModuleName(node, node.moduleSpecifier); + if (moduleExisted) { + forEach(importClause.namedBindings.elements, checkImportBinding); + } + } + } + } + } + checkImportAttributes(node); + } + + function checkImportEqualsDeclaration(node: ImportEqualsDeclaration) { + if (checkGrammarModuleElementContext(node, isInJSFile(node) ? Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_module : Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_namespace_or_module)) { + // If we hit an import declaration in an illegal context, just bail out to avoid cascading errors. + return; + } + + checkGrammarModifiers(node); + if (isInternalModuleImportEqualsDeclaration(node) || checkExternalImportOrExportDeclaration(node)) { + checkImportBinding(node); + markLinkedReferences(node, ReferenceHint.ExportImportEquals); + if (node.moduleReference.kind !== SyntaxKind.ExternalModuleReference) { + const target = resolveAlias(getSymbolOfDeclaration(node)); + if (target !== unknownSymbol) { + const targetFlags = getSymbolFlags(target); + if (targetFlags & SymbolFlags.Value) { + // Target is a value symbol, check that it is not hidden by a local declaration with the same name + const moduleName = getFirstIdentifier(node.moduleReference); + if (!(resolveEntityName(moduleName, SymbolFlags.Value | SymbolFlags.Namespace)!.flags & SymbolFlags.Namespace)) { + error(moduleName, Diagnostics.Module_0_is_hidden_by_a_local_declaration_with_the_same_name, declarationNameToString(moduleName)); + } + } + if (targetFlags & SymbolFlags.Type) { + checkTypeNameIsReserved(node.name, Diagnostics.Import_name_cannot_be_0); + } + } + if (node.isTypeOnly) { + grammarErrorOnNode(node, Diagnostics.An_import_alias_cannot_use_import_type); + } + } + else { + if (moduleKind >= ModuleKind.ES2015 && moduleKind !== ModuleKind.Preserve && getSourceFileOfNode(node).impliedNodeFormat === undefined && !node.isTypeOnly && !(node.flags & NodeFlags.Ambient)) { + // Import equals declaration is deprecated in es6 or above + grammarErrorOnNode(node, Diagnostics.Import_assignment_cannot_be_used_when_targeting_ECMAScript_modules_Consider_using_import_Asterisk_as_ns_from_mod_import_a_from_mod_import_d_from_mod_or_another_module_format_instead); + } + } + } + } + + function checkExportDeclaration(node: ExportDeclaration) { + if (checkGrammarModuleElementContext(node, isInJSFile(node) ? Diagnostics.An_export_declaration_can_only_be_used_at_the_top_level_of_a_module : Diagnostics.An_export_declaration_can_only_be_used_at_the_top_level_of_a_namespace_or_module)) { + // If we hit an export in an illegal context, just bail out to avoid cascading errors. + return; + } + + if (!checkGrammarModifiers(node) && hasSyntacticModifiers(node)) { + grammarErrorOnFirstToken(node, Diagnostics.An_export_declaration_cannot_have_modifiers); + } + + checkGrammarExportDeclaration(node); + if (!node.moduleSpecifier || checkExternalImportOrExportDeclaration(node)) { + if (node.exportClause && !isNamespaceExport(node.exportClause)) { + // export { x, y } + // export { x, y } from "foo" + forEach(node.exportClause.elements, checkExportSpecifier); + const inAmbientExternalModule = node.parent.kind === SyntaxKind.ModuleBlock && isAmbientModule(node.parent.parent); + const inAmbientNamespaceDeclaration = !inAmbientExternalModule && node.parent.kind === SyntaxKind.ModuleBlock && + !node.moduleSpecifier && node.flags & NodeFlags.Ambient; + if (node.parent.kind !== SyntaxKind.SourceFile && !inAmbientExternalModule && !inAmbientNamespaceDeclaration) { + error(node, Diagnostics.Export_declarations_are_not_permitted_in_a_namespace); + } + } + else { + // export * from "foo" + // export * as ns from "foo"; + const moduleSymbol = resolveExternalModuleName(node, node.moduleSpecifier!); + if (moduleSymbol && hasExportAssignmentSymbol(moduleSymbol)) { + error(node.moduleSpecifier, Diagnostics.Module_0_uses_export_and_cannot_be_used_with_export_Asterisk, symbolToString(moduleSymbol)); + } + else if (node.exportClause) { + checkAliasSymbol(node.exportClause); + checkModuleExportName(node.exportClause.name); + } + if (moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS)) { + if (node.exportClause) { + // export * as ns from "foo"; + // For ES2015 modules, we emit it as a pair of `import * as a_1 ...; export { a_1 as ns }` and don't need the helper. + // We only use the helper here when in esModuleInterop + if (getESModuleInterop(compilerOptions)) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportStar); + } + } + else { + // export * from "foo" + checkExternalEmitHelpers(node, ExternalEmitHelpers.ExportStar); + } + } + } + } + checkImportAttributes(node); + } + + function checkGrammarExportDeclaration(node: ExportDeclaration): boolean { + if (node.isTypeOnly && node.exportClause?.kind === SyntaxKind.NamedExports) { + return checkGrammarNamedImportsOrExports(node.exportClause); + } + return false; + } + + function checkGrammarModuleElementContext(node: Statement, errorMessage: DiagnosticMessage): boolean { + const isInAppropriateContext = node.parent.kind === SyntaxKind.SourceFile || node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.ModuleDeclaration; + if (!isInAppropriateContext) { + grammarErrorOnFirstToken(node, errorMessage); + } + return !isInAppropriateContext; + } + + function checkExportSpecifier(node: ExportSpecifier) { + checkAliasSymbol(node); + const hasModuleSpecifier = node.parent.parent.moduleSpecifier !== undefined; + checkModuleExportName(node.propertyName, hasModuleSpecifier); + checkModuleExportName(node.name); + if (getEmitDeclarations(compilerOptions)) { + collectLinkedAliases(node.propertyName || node.name, /*setVisibility*/ true); + } + if (!hasModuleSpecifier) { + const exportedName = node.propertyName || node.name; + if (exportedName.kind === SyntaxKind.StringLiteral) { + return; // Skip for invalid syntax like this: export { "x" } + } + // find immediate value referenced by exported name (SymbolFlags.Alias is set so we don't chase down aliases) + const symbol = resolveName(exportedName, exportedName.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (symbol && (symbol === undefinedSymbol || symbol === globalThisSymbol || symbol.declarations && isGlobalSourceFile(getDeclarationContainer(symbol.declarations[0])))) { + error(exportedName, Diagnostics.Cannot_export_0_Only_local_declarations_can_be_exported_from_a_module, idText(exportedName)); + } + else { + markLinkedReferences(node, ReferenceHint.ExportSpecifier); + } + } + else { + if ( + getESModuleInterop(compilerOptions) && + moduleKind !== ModuleKind.System && + (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) && + moduleExportNameIsDefault(node.propertyName || node.name) + ) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportDefault); + } + } + } + + function checkExportAssignment(node: ExportAssignment) { + const illegalContextMessage = node.isExportEquals + ? Diagnostics.An_export_assignment_must_be_at_the_top_level_of_a_file_or_module_declaration + : Diagnostics.A_default_export_must_be_at_the_top_level_of_a_file_or_module_declaration; + if (checkGrammarModuleElementContext(node, illegalContextMessage)) { + // If we hit an export assignment in an illegal context, just bail out to avoid cascading errors. + return; + } + + const container = node.parent.kind === SyntaxKind.SourceFile ? node.parent : node.parent.parent as ModuleDeclaration; + if (container.kind === SyntaxKind.ModuleDeclaration && !isAmbientModule(container)) { + if (node.isExportEquals) { + error(node, Diagnostics.An_export_assignment_cannot_be_used_in_a_namespace); + } + else { + error(node, Diagnostics.A_default_export_can_only_be_used_in_an_ECMAScript_style_module); + } + + return; + } + // Grammar checking + if (!checkGrammarModifiers(node) && hasEffectiveModifiers(node)) { + grammarErrorOnFirstToken(node, Diagnostics.An_export_assignment_cannot_have_modifiers); + } + + const typeAnnotationNode = getEffectiveTypeAnnotationNode(node); + if (typeAnnotationNode) { + checkTypeAssignableTo(checkExpressionCached(node.expression), getTypeFromTypeNode(typeAnnotationNode), node.expression); + } + + const isIllegalExportDefaultInCJS = !node.isExportEquals && + !(node.flags & NodeFlags.Ambient) && + compilerOptions.verbatimModuleSyntax && + (moduleKind === ModuleKind.CommonJS || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS); + + if (node.expression.kind === SyntaxKind.Identifier) { + const id = node.expression as Identifier; + const sym = getExportSymbolOfValueSymbolIfExported(resolveEntityName(id, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, node)); + if (sym) { + markLinkedReferences(node, ReferenceHint.ExportAssignment); + const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(sym, SymbolFlags.Value); + // If not a value, we're interpreting the identifier as a type export, along the lines of (`export { Id as default }`) + if (getSymbolFlags(sym) & SymbolFlags.Value) { + // However if it is a value, we need to check it's being used correctly + checkExpressionCached(id); + if (!isIllegalExportDefaultInCJS && !(node.flags & NodeFlags.Ambient) && compilerOptions.verbatimModuleSyntax && typeOnlyDeclaration) { + error( + id, + node.isExportEquals + ? Diagnostics.An_export_declaration_must_reference_a_real_value_when_verbatimModuleSyntax_is_enabled_but_0_resolves_to_a_type_only_declaration + : Diagnostics.An_export_default_must_reference_a_real_value_when_verbatimModuleSyntax_is_enabled_but_0_resolves_to_a_type_only_declaration, + idText(id), + ); + } + } + else if (!isIllegalExportDefaultInCJS && !(node.flags & NodeFlags.Ambient) && compilerOptions.verbatimModuleSyntax) { + error( + id, + node.isExportEquals + ? Diagnostics.An_export_declaration_must_reference_a_value_when_verbatimModuleSyntax_is_enabled_but_0_only_refers_to_a_type + : Diagnostics.An_export_default_must_reference_a_value_when_verbatimModuleSyntax_is_enabled_but_0_only_refers_to_a_type, + idText(id), + ); + } + + if (!isIllegalExportDefaultInCJS && !(node.flags & NodeFlags.Ambient) && getIsolatedModules(compilerOptions) && !(sym.flags & SymbolFlags.Value)) { + const nonLocalMeanings = getSymbolFlags(sym, /*excludeTypeOnlyMeanings*/ false, /*excludeLocalMeanings*/ true); + if ( + sym.flags & SymbolFlags.Alias + && nonLocalMeanings & SymbolFlags.Type + && !(nonLocalMeanings & SymbolFlags.Value) + && (!typeOnlyDeclaration || getSourceFileOfNode(typeOnlyDeclaration) !== getSourceFileOfNode(node)) + ) { + // import { SomeType } from "./someModule"; + // export default SomeType; OR + // export = SomeType; + error( + id, + node.isExportEquals ? + Diagnostics._0_resolves_to_a_type_and_must_be_marked_type_only_in_this_file_before_re_exporting_when_1_is_enabled_Consider_using_import_type_where_0_is_imported + : Diagnostics._0_resolves_to_a_type_and_must_be_marked_type_only_in_this_file_before_re_exporting_when_1_is_enabled_Consider_using_export_type_0_as_default, + idText(id), + isolatedModulesLikeFlagName, + ); + } + else if (typeOnlyDeclaration && getSourceFileOfNode(typeOnlyDeclaration) !== getSourceFileOfNode(node)) { + // import { SomeTypeOnlyValue } from "./someModule"; + // export default SomeTypeOnlyValue; OR + // export = SomeTypeOnlyValue; + addTypeOnlyDeclarationRelatedInfo( + error( + id, + node.isExportEquals ? + Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_marked_type_only_in_this_file_before_re_exporting_when_1_is_enabled_Consider_using_import_type_where_0_is_imported + : Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_marked_type_only_in_this_file_before_re_exporting_when_1_is_enabled_Consider_using_export_type_0_as_default, + idText(id), + isolatedModulesLikeFlagName, + ), + typeOnlyDeclaration, + idText(id), + ); + } + } + } + else { + checkExpressionCached(id); // doesn't resolve, check as expression to mark as error + } + + if (getEmitDeclarations(compilerOptions)) { + collectLinkedAliases(id, /*setVisibility*/ true); + } + } + else { + checkExpressionCached(node.expression); + } + + if (isIllegalExportDefaultInCJS) { + error(node, Diagnostics.ESM_syntax_is_not_allowed_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + + checkExternalModuleExports(container); + + if ((node.flags & NodeFlags.Ambient) && !isEntityNameExpression(node.expression)) { + grammarErrorOnNode(node.expression, Diagnostics.The_expression_of_an_export_assignment_must_be_an_identifier_or_qualified_name_in_an_ambient_context); + } + + if (node.isExportEquals) { + // Forbid export= in esm implementation files, and esm mode declaration files + if ( + moduleKind >= ModuleKind.ES2015 && + moduleKind !== ModuleKind.Preserve && + ((node.flags & NodeFlags.Ambient && getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.ESNext) || + (!(node.flags & NodeFlags.Ambient) && getSourceFileOfNode(node).impliedNodeFormat !== ModuleKind.CommonJS)) + ) { + // export assignment is not supported in es6 modules + grammarErrorOnNode(node, Diagnostics.Export_assignment_cannot_be_used_when_targeting_ECMAScript_modules_Consider_using_export_default_or_another_module_format_instead); + } + else if (moduleKind === ModuleKind.System && !(node.flags & NodeFlags.Ambient)) { + // system modules does not support export assignment + grammarErrorOnNode(node, Diagnostics.Export_assignment_is_not_supported_when_module_flag_is_system); + } + } + } + + function hasExportedMembers(moduleSymbol: Symbol) { + return forEachEntry(moduleSymbol.exports!, (_, id) => id !== "export="); + } + + function checkExternalModuleExports(node: SourceFile | ModuleDeclaration) { + const moduleSymbol = getSymbolOfDeclaration(node); + const links = getSymbolLinks(moduleSymbol); + if (!links.exportsChecked) { + const exportEqualsSymbol = moduleSymbol.exports!.get("export=" as __String); + if (exportEqualsSymbol && hasExportedMembers(moduleSymbol)) { + const declaration = getDeclarationOfAliasSymbol(exportEqualsSymbol) || exportEqualsSymbol.valueDeclaration; + if (declaration && !isTopLevelInExternalModuleAugmentation(declaration) && !isInJSFile(declaration)) { + error(declaration, Diagnostics.An_export_assignment_cannot_be_used_in_a_module_with_other_exported_elements); + } + } + // Checks for export * conflicts + const exports = getExportsOfModule(moduleSymbol); + if (exports) { + exports.forEach(({ declarations, flags }, id) => { + if (id === "__export") { + return; + } + // ECMA262: 15.2.1.1 It is a Syntax Error if the ExportedNames of ModuleItemList contains any duplicate entries. + // (TS Exceptions: namespaces, function overloads, enums, and interfaces) + if (flags & (SymbolFlags.Namespace | SymbolFlags.Enum)) { + return; + } + const exportedDeclarationsCount = countWhere(declarations, and(isNotOverloadAndNotAccessor, not(isInterfaceDeclaration))); + if (flags & SymbolFlags.TypeAlias && exportedDeclarationsCount <= 2) { + // it is legal to merge type alias with other values + // so count should be either 1 (just type alias) or 2 (type alias + merged value) + return; + } + if (exportedDeclarationsCount > 1) { + if (!isDuplicatedCommonJSExport(declarations)) { + for (const declaration of declarations!) { + if (isNotOverload(declaration)) { + diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Cannot_redeclare_exported_variable_0, unescapeLeadingUnderscores(id))); + } + } + } + } + }); + } + links.exportsChecked = true; + } + } + + function isDuplicatedCommonJSExport(declarations: Declaration[] | undefined) { + return declarations + && declarations.length > 1 + && declarations.every(d => isInJSFile(d) && isAccessExpression(d) && (isExportsIdentifier(d.expression) || isModuleExportsAccessExpression(d.expression))); + } + + function checkSourceElement(node: Node | undefined): void { + if (node) { + const saveCurrentNode = currentNode; + currentNode = node; + instantiationCount = 0; + checkSourceElementWorker(node); + currentNode = saveCurrentNode; + } + } + + function checkSourceElementWorker(node: Node): void { + if (getNodeCheckFlags(node) & NodeCheckFlags.PartiallyTypeChecked) { + return; + } + + if (canHaveJSDoc(node)) { + forEach(node.jsDoc, ({ comment, tags }) => { + checkJSDocCommentWorker(comment); + forEach(tags, tag => { + checkJSDocCommentWorker(tag.comment); + if (isInJSFile(node)) { + checkSourceElement(tag); + } + }); + }); + } + + const kind = node.kind; + if (cancellationToken) { + // Only bother checking on a few construct kinds. We don't want to be excessively + // hitting the cancellation token on every node we check. + switch (kind) { + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.FunctionDeclaration: + cancellationToken.throwIfCancellationRequested(); + } + } + if (kind >= SyntaxKind.FirstStatement && kind <= SyntaxKind.LastStatement && canHaveFlowNode(node) && node.flowNode && !isReachableFlowNode(node.flowNode)) { + errorOrSuggestion(compilerOptions.allowUnreachableCode === false, node, Diagnostics.Unreachable_code_detected); + } + + // If editing this, keep `isSourceElement` in utilities up to date. + switch (kind) { + case SyntaxKind.TypeParameter: + return checkTypeParameter(node as TypeParameterDeclaration); + case SyntaxKind.Parameter: + return checkParameter(node as ParameterDeclaration); + case SyntaxKind.PropertyDeclaration: + return checkPropertyDeclaration(node as PropertyDeclaration); + case SyntaxKind.PropertySignature: + return checkPropertySignature(node as PropertySignature); + case SyntaxKind.ConstructorType: + case SyntaxKind.FunctionType: + case SyntaxKind.CallSignature: + case SyntaxKind.ConstructSignature: + case SyntaxKind.IndexSignature: + return checkSignatureDeclaration(node as SignatureDeclaration); + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + return checkMethodDeclaration(node as MethodDeclaration | MethodSignature); + case SyntaxKind.ClassStaticBlockDeclaration: + return checkClassStaticBlockDeclaration(node as ClassStaticBlockDeclaration); + case SyntaxKind.Constructor: + return checkConstructorDeclaration(node as ConstructorDeclaration); + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return checkAccessorDeclaration(node as AccessorDeclaration); + case SyntaxKind.TypeReference: + return checkTypeReferenceNode(node as TypeReferenceNode); + case SyntaxKind.TypePredicate: + return checkTypePredicate(node as TypePredicateNode); + case SyntaxKind.TypeQuery: + return checkTypeQuery(node as TypeQueryNode); + case SyntaxKind.TypeLiteral: + return checkTypeLiteral(node as TypeLiteralNode); + case SyntaxKind.ArrayType: + return checkArrayType(node as ArrayTypeNode); + case SyntaxKind.TupleType: + return checkTupleType(node as TupleTypeNode); + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + return checkUnionOrIntersectionType(node as UnionOrIntersectionTypeNode); + case SyntaxKind.ParenthesizedType: + case SyntaxKind.OptionalType: + case SyntaxKind.RestType: + return checkSourceElement((node as ParenthesizedTypeNode | OptionalTypeNode | RestTypeNode).type); + case SyntaxKind.ThisType: + return checkThisType(node as ThisTypeNode); + case SyntaxKind.TypeOperator: + return checkTypeOperator(node as TypeOperatorNode); + case SyntaxKind.ConditionalType: + return checkConditionalType(node as ConditionalTypeNode); + case SyntaxKind.InferType: + return checkInferType(node as InferTypeNode); + case SyntaxKind.TemplateLiteralType: + return checkTemplateLiteralType(node as TemplateLiteralTypeNode); + case SyntaxKind.ImportType: + return checkImportType(node as ImportTypeNode); + case SyntaxKind.NamedTupleMember: + return checkNamedTupleMember(node as NamedTupleMember); + case SyntaxKind.JSDocAugmentsTag: + return checkJSDocAugmentsTag(node as JSDocAugmentsTag); + case SyntaxKind.JSDocImplementsTag: + return checkJSDocImplementsTag(node as JSDocImplementsTag); + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.JSDocEnumTag: + return checkJSDocTypeAliasTag(node as JSDocTypedefTag); + case SyntaxKind.JSDocTemplateTag: + return checkJSDocTemplateTag(node as JSDocTemplateTag); + case SyntaxKind.JSDocTypeTag: + return checkJSDocTypeTag(node as JSDocTypeTag); + case SyntaxKind.JSDocLink: + case SyntaxKind.JSDocLinkCode: + case SyntaxKind.JSDocLinkPlain: + return checkJSDocLinkLikeTag(node as JSDocLink | JSDocLinkCode | JSDocLinkPlain); + case SyntaxKind.JSDocParameterTag: + return checkJSDocParameterTag(node as JSDocParameterTag); + case SyntaxKind.JSDocPropertyTag: + return checkJSDocPropertyTag(node as JSDocPropertyTag); + case SyntaxKind.JSDocFunctionType: + checkJSDocFunctionType(node as JSDocFunctionType); + // falls through + case SyntaxKind.JSDocNonNullableType: + case SyntaxKind.JSDocNullableType: + case SyntaxKind.JSDocAllType: + case SyntaxKind.JSDocUnknownType: + case SyntaxKind.JSDocTypeLiteral: + checkJSDocTypeIsInJsFile(node); + forEachChild(node, checkSourceElement); + return; + case SyntaxKind.JSDocVariadicType: + checkJSDocVariadicType(node as JSDocVariadicType); + return; + case SyntaxKind.JSDocTypeExpression: + return checkSourceElement((node as JSDocTypeExpression).type); + case SyntaxKind.JSDocPublicTag: + case SyntaxKind.JSDocProtectedTag: + case SyntaxKind.JSDocPrivateTag: + return checkJSDocAccessibilityModifiers(node as JSDocPublicTag | JSDocProtectedTag | JSDocPrivateTag); + case SyntaxKind.JSDocSatisfiesTag: + return checkJSDocSatisfiesTag(node as JSDocSatisfiesTag); + case SyntaxKind.JSDocThisTag: + return checkJSDocThisTag(node as JSDocThisTag); + case SyntaxKind.JSDocImportTag: + return checkJSDocImportTag(node as JSDocImportTag); + case SyntaxKind.IndexedAccessType: + return checkIndexedAccessType(node as IndexedAccessTypeNode); + case SyntaxKind.MappedType: + return checkMappedType(node as MappedTypeNode); + case SyntaxKind.FunctionDeclaration: + return checkFunctionDeclaration(node as FunctionDeclaration); + case SyntaxKind.Block: + case SyntaxKind.ModuleBlock: + return checkBlock(node as Block); + case SyntaxKind.VariableStatement: + return checkVariableStatement(node as VariableStatement); + case SyntaxKind.ExpressionStatement: + return checkExpressionStatement(node as ExpressionStatement); + case SyntaxKind.IfStatement: + return checkIfStatement(node as IfStatement); + case SyntaxKind.DoStatement: + return checkDoStatement(node as DoStatement); + case SyntaxKind.WhileStatement: + return checkWhileStatement(node as WhileStatement); + case SyntaxKind.ForStatement: + return checkForStatement(node as ForStatement); + case SyntaxKind.ForInStatement: + return checkForInStatement(node as ForInStatement); + case SyntaxKind.ForOfStatement: + return checkForOfStatement(node as ForOfStatement); + case SyntaxKind.ContinueStatement: + case SyntaxKind.BreakStatement: + return checkBreakOrContinueStatement(node as BreakOrContinueStatement); + case SyntaxKind.ReturnStatement: + return checkReturnStatement(node as ReturnStatement); + case SyntaxKind.WithStatement: + return checkWithStatement(node as WithStatement); + case SyntaxKind.SwitchStatement: + return checkSwitchStatement(node as SwitchStatement); + case SyntaxKind.LabeledStatement: + return checkLabeledStatement(node as LabeledStatement); + case SyntaxKind.ThrowStatement: + return checkThrowStatement(node as ThrowStatement); + case SyntaxKind.TryStatement: + return checkTryStatement(node as TryStatement); + case SyntaxKind.VariableDeclaration: + return checkVariableDeclaration(node as VariableDeclaration); + case SyntaxKind.BindingElement: + return checkBindingElement(node as BindingElement); + case SyntaxKind.ClassDeclaration: + return checkClassDeclaration(node as ClassDeclaration); + case SyntaxKind.InterfaceDeclaration: + return checkInterfaceDeclaration(node as InterfaceDeclaration); + case SyntaxKind.TypeAliasDeclaration: + return checkTypeAliasDeclaration(node as TypeAliasDeclaration); + case SyntaxKind.EnumDeclaration: + return checkEnumDeclaration(node as EnumDeclaration); + case SyntaxKind.ModuleDeclaration: + return checkModuleDeclaration(node as ModuleDeclaration); + case SyntaxKind.ImportDeclaration: + return checkImportDeclaration(node as ImportDeclaration); + case SyntaxKind.ImportEqualsDeclaration: + return checkImportEqualsDeclaration(node as ImportEqualsDeclaration); + case SyntaxKind.ExportDeclaration: + return checkExportDeclaration(node as ExportDeclaration); + case SyntaxKind.ExportAssignment: + return checkExportAssignment(node as ExportAssignment); + case SyntaxKind.EmptyStatement: + case SyntaxKind.DebuggerStatement: + checkGrammarStatementInAmbientContext(node); + return; + case SyntaxKind.MissingDeclaration: + return checkMissingDeclaration(node); + } + } + + function checkJSDocCommentWorker(node: string | readonly JSDocComment[] | undefined) { + if (isArray(node)) { + forEach(node, tag => { + if (isJSDocLinkLike(tag)) { + checkSourceElement(tag); + } + }); + } + } + + function checkJSDocTypeIsInJsFile(node: Node): void { + if (!isInJSFile(node)) { + if (isJSDocNonNullableType(node) || isJSDocNullableType(node)) { + const token = tokenToString(isJSDocNonNullableType(node) ? SyntaxKind.ExclamationToken : SyntaxKind.QuestionToken); + const diagnostic = node.postfix + ? Diagnostics._0_at_the_end_of_a_type_is_not_valid_TypeScript_syntax_Did_you_mean_to_write_1 + : Diagnostics._0_at_the_start_of_a_type_is_not_valid_TypeScript_syntax_Did_you_mean_to_write_1; + const typeNode = node.type; + const type = getTypeFromTypeNode(typeNode); + grammarErrorOnNode( + node, + diagnostic, + token, + typeToString( + isJSDocNullableType(node) && !(type === neverType || type === voidType) + ? getUnionType(append([type, undefinedType], node.postfix ? undefined : nullType)) : type, + ), + ); + } + else { + grammarErrorOnNode(node, Diagnostics.JSDoc_types_can_only_be_used_inside_documentation_comments); + } + } + } + + function checkJSDocVariadicType(node: JSDocVariadicType): void { + checkJSDocTypeIsInJsFile(node); + checkSourceElement(node.type); + + // Only legal location is in the *last* parameter tag or last parameter of a JSDoc function. + const { parent } = node; + if (isParameter(parent) && isJSDocFunctionType(parent.parent)) { + if (last(parent.parent.parameters) !== parent) { + error(node, Diagnostics.A_rest_parameter_must_be_last_in_a_parameter_list); + } + return; + } + + if (!isJSDocTypeExpression(parent)) { + error(node, Diagnostics.JSDoc_may_only_appear_in_the_last_parameter_of_a_signature); + } + + const paramTag = node.parent.parent; + if (!isJSDocParameterTag(paramTag)) { + error(node, Diagnostics.JSDoc_may_only_appear_in_the_last_parameter_of_a_signature); + return; + } + + const param = getParameterSymbolFromJSDoc(paramTag); + if (!param) { + // We will error in `checkJSDocParameterTag`. + return; + } + + const host = getHostSignatureFromJSDoc(paramTag); + if (!host || last(host.parameters).symbol !== param) { + error(node, Diagnostics.A_rest_parameter_must_be_last_in_a_parameter_list); + } + } + + function getTypeFromJSDocVariadicType(node: JSDocVariadicType): Type { + const type = getTypeFromTypeNode(node.type); + const { parent } = node; + const paramTag = node.parent.parent; + if (isJSDocTypeExpression(node.parent) && isJSDocParameterTag(paramTag)) { + // Else we will add a diagnostic, see `checkJSDocVariadicType`. + const host = getHostSignatureFromJSDoc(paramTag); + const isCallbackTag = isJSDocCallbackTag(paramTag.parent.parent); + if (host || isCallbackTag) { + /* + Only return an array type if the corresponding parameter is marked as a rest parameter, or if there are no parameters. + So in the following situation we will not create an array type: + /** @param {...number} a * / + function f(a) {} + Because `a` will just be of type `number | undefined`. A synthetic `...args` will also be added, which *will* get an array type. + */ + const lastParamDeclaration = isCallbackTag + ? lastOrUndefined((paramTag.parent.parent as unknown as JSDocCallbackTag).typeExpression.parameters) + : lastOrUndefined(host!.parameters); + const symbol = getParameterSymbolFromJSDoc(paramTag); + if ( + !lastParamDeclaration || + symbol && lastParamDeclaration.symbol === symbol && isRestParameter(lastParamDeclaration) + ) { + return createArrayType(type); + } + } + } + if (isParameter(parent) && isJSDocFunctionType(parent.parent)) { + return createArrayType(type); + } + return addOptionality(type); + } + + // Function and class expression bodies are checked after all statements in the enclosing body. This is + // to ensure constructs like the following are permitted: + // const foo = function () { + // const s = foo(); + // return "hello"; + // } + // Here, performing a full type check of the body of the function expression whilst in the process of + // determining the type of foo would cause foo to be given type any because of the recursive reference. + // Delaying the type check of the body ensures foo has been assigned a type. + function checkNodeDeferred(node: Node) { + const enclosingFile = getSourceFileOfNode(node); + const links = getNodeLinks(enclosingFile); + if (!(links.flags & NodeCheckFlags.TypeChecked)) { + links.deferredNodes ||= new Set(); + links.deferredNodes.add(node); + } + else { + Debug.assert(!links.deferredNodes, "A type-checked file should have no deferred nodes."); + } + } + + function checkDeferredNodes(context: SourceFile) { + const links = getNodeLinks(context); + if (links.deferredNodes) { + links.deferredNodes.forEach(checkDeferredNode); + } + links.deferredNodes = undefined; + } + + function checkDeferredNode(node: Node) { + tracing?.push(tracing.Phase.Check, "checkDeferredNode", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); + const saveCurrentNode = currentNode; + currentNode = node; + instantiationCount = 0; + switch (node.kind) { + case SyntaxKind.CallExpression: + case SyntaxKind.NewExpression: + case SyntaxKind.TaggedTemplateExpression: + case SyntaxKind.Decorator: + case SyntaxKind.JsxOpeningElement: + // These node kinds are deferred checked when overload resolution fails + // To save on work, we ensure the arguments are checked just once, in + // a deferred way + resolveUntypedCall(node as CallLikeExpression); + break; + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + checkFunctionExpressionOrObjectLiteralMethodDeferred(node as FunctionExpression); + break; + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + checkAccessorDeclaration(node as AccessorDeclaration); + break; + case SyntaxKind.ClassExpression: + checkClassExpressionDeferred(node as ClassExpression); + break; + case SyntaxKind.TypeParameter: + checkTypeParameterDeferred(node as TypeParameterDeclaration); + break; + case SyntaxKind.JsxSelfClosingElement: + checkJsxSelfClosingElementDeferred(node as JsxSelfClosingElement); + break; + case SyntaxKind.JsxElement: + checkJsxElementDeferred(node as JsxElement); + break; + case SyntaxKind.TypeAssertionExpression: + case SyntaxKind.AsExpression: + case SyntaxKind.ParenthesizedExpression: + checkAssertionDeferred(node as AssertionExpression | JSDocTypeAssertion); + break; + case SyntaxKind.VoidExpression: + checkExpression((node as VoidExpression).expression); + break; + case SyntaxKind.BinaryExpression: + if (isInstanceOfExpression(node)) { + resolveUntypedCall(node); + } + break; + } + currentNode = saveCurrentNode; + tracing?.pop(); + } + + function checkSourceFile(node: SourceFile, nodesToCheck: Node[] | undefined) { + tracing?.push(tracing.Phase.Check, nodesToCheck ? "checkSourceFileNodes" : "checkSourceFile", { path: node.path }, /*separateBeginAndEnd*/ true); + const beforeMark = nodesToCheck ? "beforeCheckNodes" : "beforeCheck"; + const afterMark = nodesToCheck ? "afterCheckNodes" : "afterCheck"; + performance.mark(beforeMark); + nodesToCheck ? checkSourceFileNodesWorker(node, nodesToCheck) : checkSourceFileWorker(node); + performance.mark(afterMark); + performance.measure("Check", beforeMark, afterMark); + tracing?.pop(); + } + + function unusedIsError(kind: UnusedKind, isAmbient: boolean): boolean { + if (isAmbient) { + return false; + } + switch (kind) { + case UnusedKind.Local: + return !!compilerOptions.noUnusedLocals; + case UnusedKind.Parameter: + return !!compilerOptions.noUnusedParameters; + default: + return Debug.assertNever(kind); + } + } + + function getPotentiallyUnusedIdentifiers(sourceFile: SourceFile): readonly PotentiallyUnusedIdentifier[] { + return allPotentiallyUnusedIdentifiers.get(sourceFile.path) || emptyArray; + } + + // Fully type check a source file and collect the relevant diagnostics. + function checkSourceFileWorker(node: SourceFile) { + const links = getNodeLinks(node); + if (!(links.flags & NodeCheckFlags.TypeChecked)) { + if (skipTypeChecking(node, compilerOptions, host)) { + return; + } + + // Grammar checking + checkGrammarSourceFile(node); + + clear(potentialThisCollisions); + clear(potentialNewTargetCollisions); + clear(potentialWeakMapSetCollisions); + clear(potentialReflectCollisions); + clear(potentialUnusedRenamedBindingElementsInTypes); + + if (links.flags & NodeCheckFlags.PartiallyTypeChecked) { + potentialThisCollisions = links.potentialThisCollisions!; + potentialNewTargetCollisions = links.potentialNewTargetCollisions!; + potentialWeakMapSetCollisions = links.potentialWeakMapSetCollisions!; + potentialReflectCollisions = links.potentialReflectCollisions!; + potentialUnusedRenamedBindingElementsInTypes = links.potentialUnusedRenamedBindingElementsInTypes!; + } + + forEach(node.statements, checkSourceElement); + checkSourceElement(node.endOfFileToken); + + checkDeferredNodes(node); + + if (isExternalOrCommonJsModule(node)) { + registerForUnusedIdentifiersCheck(node); + } + + addLazyDiagnostic(() => { + // This relies on the results of other lazy diagnostics, so must be computed after them + if (!node.isDeclarationFile && (compilerOptions.noUnusedLocals || compilerOptions.noUnusedParameters)) { + checkUnusedIdentifiers(getPotentiallyUnusedIdentifiers(node), (containingNode, kind, diag) => { + if (!containsParseError(containingNode) && unusedIsError(kind, !!(containingNode.flags & NodeFlags.Ambient))) { + diagnostics.add(diag); + } + }); + } + if (!node.isDeclarationFile) { + checkPotentialUncheckedRenamedBindingElementsInTypes(); + } + }); + + if (isExternalOrCommonJsModule(node)) { + checkExternalModuleExports(node); + } + + if (potentialThisCollisions.length) { + forEach(potentialThisCollisions, checkIfThisIsCapturedInEnclosingScope); + clear(potentialThisCollisions); + } + + if (potentialNewTargetCollisions.length) { + forEach(potentialNewTargetCollisions, checkIfNewTargetIsCapturedInEnclosingScope); + clear(potentialNewTargetCollisions); + } + + if (potentialWeakMapSetCollisions.length) { + forEach(potentialWeakMapSetCollisions, checkWeakMapSetCollision); + clear(potentialWeakMapSetCollisions); + } + + if (potentialReflectCollisions.length) { + forEach(potentialReflectCollisions, checkReflectCollision); + clear(potentialReflectCollisions); + } + + links.flags |= NodeCheckFlags.TypeChecked; + } + } + + function checkSourceFileNodesWorker(file: SourceFile, nodes: readonly Node[]) { + const links = getNodeLinks(file); + if (!(links.flags & NodeCheckFlags.TypeChecked)) { + if (skipTypeChecking(file, compilerOptions, host)) { + return; + } + + // Grammar checking + checkGrammarSourceFile(file); + + clear(potentialThisCollisions); + clear(potentialNewTargetCollisions); + clear(potentialWeakMapSetCollisions); + clear(potentialReflectCollisions); + clear(potentialUnusedRenamedBindingElementsInTypes); + + forEach(nodes, checkSourceElement); + + checkDeferredNodes(file); + + (links.potentialThisCollisions || (links.potentialThisCollisions = [])).push(...potentialThisCollisions); + (links.potentialNewTargetCollisions || (links.potentialNewTargetCollisions = [])).push(...potentialNewTargetCollisions); + (links.potentialWeakMapSetCollisions || (links.potentialWeakMapSetCollisions = [])).push(...potentialWeakMapSetCollisions); + (links.potentialReflectCollisions || (links.potentialReflectCollisions = [])).push(...potentialReflectCollisions); + (links.potentialUnusedRenamedBindingElementsInTypes || (links.potentialUnusedRenamedBindingElementsInTypes = [])).push( + ...potentialUnusedRenamedBindingElementsInTypes, + ); + + links.flags |= NodeCheckFlags.PartiallyTypeChecked; + for (const node of nodes) { + const nodeLinks = getNodeLinks(node); + nodeLinks.flags |= NodeCheckFlags.PartiallyTypeChecked; + } + } + } + + function getDiagnostics(sourceFile: SourceFile, ct: CancellationToken, nodesToCheck?: Node[]): Diagnostic[] { + try { + // Record the cancellation token so it can be checked later on during checkSourceElement. + // Do this in a finally block so we can ensure that it gets reset back to nothing after + // this call is done. + cancellationToken = ct; + return getDiagnosticsWorker(sourceFile, nodesToCheck); + } + finally { + cancellationToken = undefined; + } + } + + function ensurePendingDiagnosticWorkComplete() { + // Invoke any existing lazy diagnostics to add them, clear the backlog of diagnostics + for (const cb of deferredDiagnosticsCallbacks) { + cb(); + } + deferredDiagnosticsCallbacks = []; + } + + function checkSourceFileWithEagerDiagnostics(sourceFile: SourceFile, nodesToCheck?: Node[]) { + ensurePendingDiagnosticWorkComplete(); + // then setup diagnostics for immediate invocation (as we are about to collect them, and + // this avoids the overhead of longer-lived callbacks we don't need to allocate) + // This also serves to make the shift to possibly lazy diagnostics transparent to serial command-line scenarios + // (as in those cases, all the diagnostics will still be computed as the appropriate place in the tree, + // thus much more likely retaining the same union ordering as before we had lazy diagnostics) + const oldAddLazyDiagnostics = addLazyDiagnostic; + addLazyDiagnostic = cb => cb(); + checkSourceFile(sourceFile, nodesToCheck); + addLazyDiagnostic = oldAddLazyDiagnostics; + } + + function getDiagnosticsWorker(sourceFile: SourceFile, nodesToCheck: Node[] | undefined): Diagnostic[] { + if (sourceFile) { + ensurePendingDiagnosticWorkComplete(); + // Some global diagnostics are deferred until they are needed and + // may not be reported in the first call to getGlobalDiagnostics. + // We should catch these changes and report them. + const previousGlobalDiagnostics = diagnostics.getGlobalDiagnostics(); + const previousGlobalDiagnosticsSize = previousGlobalDiagnostics.length; + + checkSourceFileWithEagerDiagnostics(sourceFile, nodesToCheck); + const semanticDiagnostics = diagnostics.getDiagnostics(sourceFile.fileName); + if (nodesToCheck) { + // No need to get global diagnostics. + return semanticDiagnostics; + } + const currentGlobalDiagnostics = diagnostics.getGlobalDiagnostics(); + if (currentGlobalDiagnostics !== previousGlobalDiagnostics) { + // If the arrays are not the same reference, new diagnostics were added. + const deferredGlobalDiagnostics = relativeComplement(previousGlobalDiagnostics, currentGlobalDiagnostics, compareDiagnostics); + return concatenate(deferredGlobalDiagnostics, semanticDiagnostics); + } + else if (previousGlobalDiagnosticsSize === 0 && currentGlobalDiagnostics.length > 0) { + // If the arrays are the same reference, but the length has changed, a single + // new diagnostic was added as DiagnosticCollection attempts to reuse the + // same array. + return concatenate(currentGlobalDiagnostics, semanticDiagnostics); + } + + return semanticDiagnostics; + } + + // Global diagnostics are always added when a file is not provided to + // getDiagnostics + forEach(host.getSourceFiles(), file => checkSourceFileWithEagerDiagnostics(file)); + return diagnostics.getDiagnostics(); + } + + function getGlobalDiagnostics(): Diagnostic[] { + ensurePendingDiagnosticWorkComplete(); + return diagnostics.getGlobalDiagnostics(); + } + + // Language service support + + function getSymbolsInScope(location: Node, meaning: SymbolFlags): Symbol[] { + if (location.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return []; + } + + const symbols = createSymbolTable(); + let isStaticSymbol = false; + + populateSymbols(); + + symbols.delete(InternalSymbolName.This); // Not a symbol, a keyword + return symbolsToArray(symbols); + + function populateSymbols() { + while (location) { + if (canHaveLocals(location) && location.locals && !isGlobalSourceFile(location)) { + copySymbols(location.locals, meaning); + } + + switch (location.kind) { + case SyntaxKind.SourceFile: + if (!isExternalModule(location as SourceFile)) break; + // falls through + case SyntaxKind.ModuleDeclaration: + copyLocallyVisibleExportSymbols(getSymbolOfDeclaration(location as ModuleDeclaration | SourceFile).exports!, meaning & SymbolFlags.ModuleMember); + break; + case SyntaxKind.EnumDeclaration: + copySymbols(getSymbolOfDeclaration(location as EnumDeclaration).exports!, meaning & SymbolFlags.EnumMember); + break; + case SyntaxKind.ClassExpression: + const className = (location as ClassExpression).name; + if (className) { + copySymbol((location as ClassExpression).symbol, meaning); + } + + // this fall-through is necessary because we would like to handle + // type parameter inside class expression similar to how we handle it in classDeclaration and interface Declaration. + // falls through + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + // If we didn't come from static member of class or interface, + // add the type parameters into the symbol table + // (type parameters of classDeclaration/classExpression and interface are in member property of the symbol. + // Note: that the memberFlags come from previous iteration. + if (!isStaticSymbol) { + copySymbols(getMembersOfSymbol(getSymbolOfDeclaration(location as ClassDeclaration | InterfaceDeclaration)), meaning & SymbolFlags.Type); + } + break; + case SyntaxKind.FunctionExpression: + const funcName = (location as FunctionExpression).name; + if (funcName) { + copySymbol((location as FunctionExpression).symbol, meaning); + } + break; + } + + if (introducesArgumentsExoticObject(location)) { + copySymbol(argumentsSymbol, meaning); + } + + isStaticSymbol = isStatic(location); + location = location.parent; + } + + copySymbols(globals, meaning); + } + + /** + * Copy the given symbol into symbol tables if the symbol has the given meaning + * and it doesn't already existed in the symbol table + * @param key a key for storing in symbol table; if undefined, use symbol.name + * @param symbol the symbol to be added into symbol table + * @param meaning meaning of symbol to filter by before adding to symbol table + */ + function copySymbol(symbol: Symbol, meaning: SymbolFlags): void { + if (getCombinedLocalAndExportSymbolFlags(symbol) & meaning) { + const id = symbol.escapedName; + // We will copy all symbol regardless of its reserved name because + // symbolsToArray will check whether the key is a reserved name and + // it will not copy symbol with reserved name to the array + if (!symbols.has(id)) { + symbols.set(id, symbol); + } + } + } + + function copySymbols(source: SymbolTable, meaning: SymbolFlags): void { + if (meaning) { + source.forEach(symbol => { + copySymbol(symbol, meaning); + }); + } + } + + function copyLocallyVisibleExportSymbols(source: SymbolTable, meaning: SymbolFlags): void { + if (meaning) { + source.forEach(symbol => { + // Similar condition as in `resolveNameHelper` + if (!getDeclarationOfKind(symbol, SyntaxKind.ExportSpecifier) && !getDeclarationOfKind(symbol, SyntaxKind.NamespaceExport) && symbol.escapedName !== InternalSymbolName.Default) { + copySymbol(symbol, meaning); + } + }); + } + } + } + + function isTypeDeclarationName(name: Node): boolean { + return name.kind === SyntaxKind.Identifier && + isTypeDeclaration(name.parent) && + getNameOfDeclaration(name.parent) === name; + } + + // True if the given identifier is part of a type reference + function isTypeReferenceIdentifier(node: EntityName): boolean { + while (node.parent.kind === SyntaxKind.QualifiedName) { + node = node.parent as QualifiedName; + } + + return node.parent.kind === SyntaxKind.TypeReference; + } + + function isInNameOfExpressionWithTypeArguments(node: Node): boolean { + while (node.parent.kind === SyntaxKind.PropertyAccessExpression) { + node = node.parent; + } + + return node.parent.kind === SyntaxKind.ExpressionWithTypeArguments; + } + + function forEachEnclosingClass(node: Node, callback: (node: ClassLikeDeclaration) => T | undefined): T | undefined { + let result: T | undefined; + let containingClass = getContainingClass(node); + while (containingClass) { + if (result = callback(containingClass)) break; + containingClass = getContainingClass(containingClass); + } + + return result; + } + + function isNodeUsedDuringClassInitialization(node: Node) { + return !!findAncestor(node, element => { + if (isConstructorDeclaration(element) && nodeIsPresent(element.body) || isPropertyDeclaration(element)) { + return true; + } + else if (isClassLike(element) || isFunctionLikeDeclaration(element)) { + return "quit"; + } + + return false; + }); + } + + function isNodeWithinClass(node: Node, classDeclaration: ClassLikeDeclaration) { + return !!forEachEnclosingClass(node, n => n === classDeclaration); + } + + function getLeftSideOfImportEqualsOrExportAssignment(nodeOnRightSide: EntityName): ImportEqualsDeclaration | ExportAssignment | undefined { + while (nodeOnRightSide.parent.kind === SyntaxKind.QualifiedName) { + nodeOnRightSide = nodeOnRightSide.parent as QualifiedName; + } + + if (nodeOnRightSide.parent.kind === SyntaxKind.ImportEqualsDeclaration) { + return (nodeOnRightSide.parent as ImportEqualsDeclaration).moduleReference === nodeOnRightSide ? nodeOnRightSide.parent as ImportEqualsDeclaration : undefined; + } + + if (nodeOnRightSide.parent.kind === SyntaxKind.ExportAssignment) { + return (nodeOnRightSide.parent as ExportAssignment).expression === nodeOnRightSide as Node ? nodeOnRightSide.parent as ExportAssignment : undefined; + } + + return undefined; + } + + function isInRightSideOfImportOrExportAssignment(node: EntityName) { + return getLeftSideOfImportEqualsOrExportAssignment(node) !== undefined; + } + + function getSpecialPropertyAssignmentSymbolFromEntityName(entityName: EntityName | PropertyAccessExpression) { + const specialPropertyAssignmentKind = getAssignmentDeclarationKind(entityName.parent.parent as BinaryExpression); + switch (specialPropertyAssignmentKind) { + case AssignmentDeclarationKind.ExportsProperty: + case AssignmentDeclarationKind.PrototypeProperty: + return getSymbolOfNode(entityName.parent); + case AssignmentDeclarationKind.Property: + if (isPropertyAccessExpression(entityName.parent) && getLeftmostAccessExpression(entityName.parent) === entityName) { + return undefined; + } + // falls through + case AssignmentDeclarationKind.ThisProperty: + case AssignmentDeclarationKind.ModuleExports: + return getSymbolOfDeclaration(entityName.parent.parent as BinaryExpression); + } + } + + function isImportTypeQualifierPart(node: EntityName): ImportTypeNode | undefined { + let parent = node.parent; + while (isQualifiedName(parent)) { + node = parent; + parent = parent.parent; + } + if (parent && parent.kind === SyntaxKind.ImportType && (parent as ImportTypeNode).qualifier === node) { + return parent as ImportTypeNode; + } + return undefined; + } + + function isThisPropertyAndThisTyped(node: PropertyAccessExpression) { + if (node.expression.kind === SyntaxKind.ThisKeyword) { + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (isFunctionLike(container)) { + const containingLiteral = getContainingObjectLiteral(container); + if (containingLiteral) { + const contextualType = getApparentTypeOfContextualType(containingLiteral, /*contextFlags*/ undefined); + const type = getThisTypeOfObjectLiteralFromContextualType(containingLiteral, contextualType); + return type && !isTypeAny(type); + } + } + } + } + + function getSymbolOfNameOrPropertyAccessExpression(name: EntityName | PrivateIdentifier | PropertyAccessExpression | JSDocMemberName): Symbol | undefined { + if (isDeclarationName(name)) { + return getSymbolOfNode(name.parent); + } + + if ( + isInJSFile(name) && + name.parent.kind === SyntaxKind.PropertyAccessExpression && + name.parent === (name.parent.parent as BinaryExpression).left + ) { + // Check if this is a special property assignment + if (!isPrivateIdentifier(name) && !isJSDocMemberName(name) && !isThisPropertyAndThisTyped(name.parent as PropertyAccessExpression)) { + const specialPropertyAssignmentSymbol = getSpecialPropertyAssignmentSymbolFromEntityName(name); + if (specialPropertyAssignmentSymbol) { + return specialPropertyAssignmentSymbol; + } + } + } + + if (name.parent.kind === SyntaxKind.ExportAssignment && isEntityNameExpression(name)) { + // Even an entity name expression that doesn't resolve as an entityname may still typecheck as a property access expression + const success = resolveEntityName(name, /*all meanings*/ SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*ignoreErrors*/ true); + if (success && success !== unknownSymbol) { + return success; + } + } + else if (isEntityName(name) && isInRightSideOfImportOrExportAssignment(name)) { + // Since we already checked for ExportAssignment, this really could only be an Import + const importEqualsDeclaration = getAncestor(name, SyntaxKind.ImportEqualsDeclaration); + Debug.assert(importEqualsDeclaration !== undefined); + return getSymbolOfPartOfRightHandSideOfImportEquals(name, /*dontResolveAlias*/ true); + } + + if (isEntityName(name)) { + const possibleImportNode = isImportTypeQualifierPart(name); + if (possibleImportNode) { + getTypeFromTypeNode(possibleImportNode); + const sym = getNodeLinks(name).resolvedSymbol; + return sym === unknownSymbol ? undefined : sym; + } + } + + while (isRightSideOfQualifiedNameOrPropertyAccessOrJSDocMemberName(name)) { + name = name.parent as QualifiedName | PropertyAccessEntityNameExpression | JSDocMemberName; + } + + if (isInNameOfExpressionWithTypeArguments(name)) { + let meaning = SymbolFlags.None; + if (name.parent.kind === SyntaxKind.ExpressionWithTypeArguments) { + // An 'ExpressionWithTypeArguments' may appear in type space (interface Foo extends Bar), + // value space (return foo), or both(class Foo extends Bar); ensure the meaning matches. + meaning = isPartOfTypeNode(name) ? SymbolFlags.Type : SymbolFlags.Value; + + // In a class 'extends' clause we are also looking for a value. + if (isExpressionWithTypeArgumentsInClassExtendsClause(name.parent)) { + meaning |= SymbolFlags.Value; + } + } + else { + meaning = SymbolFlags.Namespace; + } + + meaning |= SymbolFlags.Alias; + const entityNameSymbol = isEntityNameExpression(name) ? resolveEntityName(name, meaning, /*ignoreErrors*/ true) : undefined; + if (entityNameSymbol) { + return entityNameSymbol; + } + } + + if (name.parent.kind === SyntaxKind.JSDocParameterTag) { + return getParameterSymbolFromJSDoc(name.parent as JSDocParameterTag); + } + + if (name.parent.kind === SyntaxKind.TypeParameter && name.parent.parent.kind === SyntaxKind.JSDocTemplateTag) { + Debug.assert(!isInJSFile(name)); // Otherwise `isDeclarationName` would have been true. + const typeParameter = getTypeParameterFromJsDoc(name.parent as TypeParameterDeclaration & { parent: JSDocTemplateTag; }); + return typeParameter && typeParameter.symbol; + } + + if (isExpressionNode(name)) { + if (nodeIsMissing(name)) { + // Missing entity name. + return undefined; + } + + const isJSDoc = findAncestor(name, or(isJSDocLinkLike, isJSDocNameReference, isJSDocMemberName)); + const meaning = isJSDoc ? SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Value : SymbolFlags.Value; + if (name.kind === SyntaxKind.Identifier) { + if (isJSXTagName(name) && isJsxIntrinsicTagName(name)) { + const symbol = getIntrinsicTagSymbol(name.parent as JsxOpeningLikeElement); + return symbol === unknownSymbol ? undefined : symbol; + } + const result = resolveEntityName(name, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, getHostSignatureFromJSDoc(name)); + if (!result && isJSDoc) { + const container = findAncestor(name, or(isClassLike, isInterfaceDeclaration)); + if (container) { + return resolveJSDocMemberName(name, /*ignoreErrors*/ true, getSymbolOfDeclaration(container)); + } + } + if (result && isJSDoc) { + const container = getJSDocHost(name); + if (container && isEnumMember(container) && container === result.valueDeclaration) { + return resolveEntityName(name, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, getSourceFileOfNode(container)) || result; + } + } + return result; + } + else if (isPrivateIdentifier(name)) { + return getSymbolForPrivateIdentifierExpression(name); + } + else if (name.kind === SyntaxKind.PropertyAccessExpression || name.kind === SyntaxKind.QualifiedName) { + const links = getNodeLinks(name); + if (links.resolvedSymbol) { + return links.resolvedSymbol; + } + + if (name.kind === SyntaxKind.PropertyAccessExpression) { + checkPropertyAccessExpression(name, CheckMode.Normal); + if (!links.resolvedSymbol) { + links.resolvedSymbol = getApplicableIndexSymbol(checkExpressionCached(name.expression), getLiteralTypeFromPropertyName(name.name)); + } + } + else { + checkQualifiedName(name, CheckMode.Normal); + } + if (!links.resolvedSymbol && isJSDoc && isQualifiedName(name)) { + return resolveJSDocMemberName(name); + } + return links.resolvedSymbol; + } + else if (isJSDocMemberName(name)) { + return resolveJSDocMemberName(name); + } + } + else if (isTypeReferenceIdentifier(name as EntityName)) { + const meaning = name.parent.kind === SyntaxKind.TypeReference ? SymbolFlags.Type : SymbolFlags.Namespace; + const symbol = resolveEntityName(name as EntityName, meaning, /*ignoreErrors*/ false, /*dontResolveAlias*/ true); + return symbol && symbol !== unknownSymbol ? symbol : getUnresolvedSymbolForEntityName(name as EntityName); + } + if (name.parent.kind === SyntaxKind.TypePredicate) { + return resolveEntityName(name as Identifier, /*meaning*/ SymbolFlags.FunctionScopedVariable); + } + + return undefined; + } + + function getApplicableIndexSymbol(type: Type, keyType: Type) { + const infos = getApplicableIndexInfos(type, keyType); + if (infos.length && (type as ObjectType).members) { + const symbol = getIndexSymbolFromSymbolTable(resolveStructuredTypeMembers(type as ObjectType).members); + if (infos === getIndexInfosOfType(type)) { + return symbol; + } + else if (symbol) { + const symbolLinks = getSymbolLinks(symbol); + const declarationList = mapDefined(infos, i => i.declaration); + const nodeListId = map(declarationList, getNodeId).join(","); + if (!symbolLinks.filteredIndexSymbolCache) { + symbolLinks.filteredIndexSymbolCache = new Map(); + } + if (symbolLinks.filteredIndexSymbolCache.has(nodeListId)) { + return symbolLinks.filteredIndexSymbolCache.get(nodeListId)!; + } + else { + const copy = createSymbol(SymbolFlags.Signature, InternalSymbolName.Index); + copy.declarations = mapDefined(infos, i => i.declaration); + copy.parent = type.aliasSymbol ? type.aliasSymbol : type.symbol ? type.symbol : getSymbolAtLocation(copy.declarations[0].parent); + symbolLinks.filteredIndexSymbolCache.set(nodeListId, copy); + return copy; + } + } + } + } + + /** + * Recursively resolve entity names and jsdoc instance references: + * 1. K#m as K.prototype.m for a class (or other value) K + * 2. K.m as K.prototype.m + * 3. I.m as I.m for a type I, or any other I.m that fails to resolve in (1) or (2) + * + * For unqualified names, a container K may be provided as a second argument. + */ + function resolveJSDocMemberName(name: EntityName | JSDocMemberName, ignoreErrors?: boolean, container?: Symbol): Symbol | undefined { + if (isEntityName(name)) { + // resolve static values first + const meaning = SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Value; + let symbol = resolveEntityName(name, meaning, ignoreErrors, /*dontResolveAlias*/ true, getHostSignatureFromJSDoc(name)); + if (!symbol && isIdentifier(name) && container) { + symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(container), name.escapedText, meaning)); + } + if (symbol) { + return symbol; + } + } + const left = isIdentifier(name) ? container : resolveJSDocMemberName(name.left, ignoreErrors, container); + const right = isIdentifier(name) ? name.escapedText : name.right.escapedText; + if (left) { + const proto = left.flags & SymbolFlags.Value && getPropertyOfType(getTypeOfSymbol(left), "prototype" as __String); + const t = proto ? getTypeOfSymbol(proto) : getDeclaredTypeOfSymbol(left); + return getPropertyOfType(t, right); + } + } + + function getSymbolAtLocation(node: Node, ignoreErrors?: boolean): Symbol | undefined { + if (isSourceFile(node)) { + return isExternalModule(node) ? getMergedSymbol(node.symbol) : undefined; + } + const { parent } = node; + const grandParent = parent.parent; + + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return undefined; + } + + if (isDeclarationNameOrImportPropertyName(node)) { + // This is a declaration, call getSymbolOfNode + const parentSymbol = getSymbolOfDeclaration(parent as Declaration); + return isImportOrExportSpecifier(node.parent) && node.parent.propertyName === node + ? getImmediateAliasedSymbol(parentSymbol) + : parentSymbol; + } + else if (isLiteralComputedPropertyDeclarationName(node)) { + return getSymbolOfDeclaration(parent.parent as Declaration); + } + + if (node.kind === SyntaxKind.Identifier) { + if (isInRightSideOfImportOrExportAssignment(node as Identifier)) { + return getSymbolOfNameOrPropertyAccessExpression(node as Identifier); + } + else if ( + parent.kind === SyntaxKind.BindingElement && + grandParent.kind === SyntaxKind.ObjectBindingPattern && + node === (parent as BindingElement).propertyName + ) { + const typeOfPattern = getTypeOfNode(grandParent); + const propertyDeclaration = getPropertyOfType(typeOfPattern, (node as Identifier).escapedText); + + if (propertyDeclaration) { + return propertyDeclaration; + } + } + else if (isMetaProperty(parent) && parent.name === node) { + if (parent.keywordToken === SyntaxKind.NewKeyword && idText(node as Identifier) === "target") { + // `target` in `new.target` + return checkNewTargetMetaProperty(parent).symbol; + } + // The `meta` in `import.meta` could be given `getTypeOfNode(parent).symbol` (the `ImportMeta` interface symbol), but + // we have a fake expression type made for other reasons already, whose transient `meta` + // member should more exactly be the kind of (declarationless) symbol we want. + // (See #44364 and #45031 for relevant implementation PRs) + if (parent.keywordToken === SyntaxKind.ImportKeyword && idText(node as Identifier) === "meta") { + return getGlobalImportMetaExpressionType().members!.get("meta" as __String); + } + // no other meta properties are valid syntax, thus no others should have symbols + return undefined; + } + } + + switch (node.kind) { + case SyntaxKind.Identifier: + case SyntaxKind.PrivateIdentifier: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.QualifiedName: + if (!isThisInTypeQuery(node)) { + return getSymbolOfNameOrPropertyAccessExpression(node as EntityName | PrivateIdentifier | PropertyAccessExpression); + } + // falls through + + case SyntaxKind.ThisKeyword: + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (isFunctionLike(container)) { + const sig = getSignatureFromDeclaration(container); + if (sig.thisParameter) { + return sig.thisParameter; + } + } + if (isInExpressionContext(node)) { + return checkExpression(node as Expression).symbol; + } + // falls through + + case SyntaxKind.ThisType: + return getTypeFromThisTypeNode(node as ThisExpression | ThisTypeNode).symbol; + + case SyntaxKind.SuperKeyword: + return checkExpression(node as Expression).symbol; + + case SyntaxKind.ConstructorKeyword: + // constructor keyword for an overload, should take us to the definition if it exist + const constructorDeclaration = node.parent; + if (constructorDeclaration && constructorDeclaration.kind === SyntaxKind.Constructor) { + return (constructorDeclaration.parent as ClassDeclaration).symbol; + } + return undefined; + + case SyntaxKind.StringLiteral: + case SyntaxKind.NoSubstitutionTemplateLiteral: + // 1). import x = require("./mo/*gotToDefinitionHere*/d") + // 2). External module name in an import declaration + // 3). Dynamic import call or require in javascript + // 4). type A = import("./f/*gotToDefinitionHere*/oo") + if ( + (isExternalModuleImportEqualsDeclaration(node.parent.parent) && getExternalModuleImportEqualsDeclarationExpression(node.parent.parent) === node) || + ((node.parent.kind === SyntaxKind.ImportDeclaration || node.parent.kind === SyntaxKind.ExportDeclaration) && (node.parent as ImportDeclaration).moduleSpecifier === node) || + (isInJSFile(node) && isJSDocImportTag(node.parent) && node.parent.moduleSpecifier === node) || + ((isInJSFile(node) && isRequireCall(node.parent, /*requireStringLiteralLikeArgument*/ false)) || isImportCall(node.parent)) || + (isLiteralTypeNode(node.parent) && isLiteralImportTypeNode(node.parent.parent) && node.parent.parent.argument === node.parent) + ) { + return resolveExternalModuleName(node, node as LiteralExpression, ignoreErrors); + } + if (isCallExpression(parent) && isBindableObjectDefinePropertyCall(parent) && parent.arguments[1] === node) { + return getSymbolOfDeclaration(parent); + } + // falls through + + case SyntaxKind.NumericLiteral: + // index access + const objectType = isElementAccessExpression(parent) + ? parent.argumentExpression === node ? getTypeOfExpression(parent.expression) : undefined + : isLiteralTypeNode(parent) && isIndexedAccessTypeNode(grandParent) + ? getTypeFromTypeNode(grandParent.objectType) + : undefined; + return objectType && getPropertyOfType(objectType, escapeLeadingUnderscores((node as StringLiteral | NumericLiteral).text)); + + case SyntaxKind.DefaultKeyword: + case SyntaxKind.FunctionKeyword: + case SyntaxKind.EqualsGreaterThanToken: + case SyntaxKind.ClassKeyword: + return getSymbolOfNode(node.parent); + case SyntaxKind.ImportType: + return isLiteralImportTypeNode(node) ? getSymbolAtLocation(node.argument.literal, ignoreErrors) : undefined; + + case SyntaxKind.ExportKeyword: + return isExportAssignment(node.parent) ? Debug.checkDefined(node.parent.symbol) : undefined; + + case SyntaxKind.ImportKeyword: + case SyntaxKind.NewKeyword: + return isMetaProperty(node.parent) ? checkMetaPropertyKeyword(node.parent).symbol : undefined; + case SyntaxKind.InstanceOfKeyword: + if (isBinaryExpression(node.parent)) { + const type = getTypeOfExpression(node.parent.right); + const hasInstanceMethodType = getSymbolHasInstanceMethodOfObjectType(type); + return hasInstanceMethodType?.symbol ?? type.symbol; + } + return undefined; + case SyntaxKind.MetaProperty: + return checkExpression(node as Expression).symbol; + case SyntaxKind.JsxNamespacedName: + if (isJSXTagName(node) && isJsxIntrinsicTagName(node)) { + const symbol = getIntrinsicTagSymbol(node.parent as JsxOpeningLikeElement); + return symbol === unknownSymbol ? undefined : symbol; + } + // falls through + + default: + return undefined; + } + } + + function getIndexInfosAtLocation(node: Node): readonly IndexInfo[] | undefined { + if (isIdentifier(node) && isPropertyAccessExpression(node.parent) && node.parent.name === node) { + const keyType = getLiteralTypeFromPropertyName(node); + const objectType = getTypeOfExpression(node.parent.expression); + const objectTypes = objectType.flags & TypeFlags.Union ? (objectType as UnionType).types : [objectType]; + return flatMap(objectTypes, t => filter(getIndexInfosOfType(t), info => isApplicableIndexType(keyType, info.keyType))); + } + return undefined; + } + + function getShorthandAssignmentValueSymbol(location: Node | undefined): Symbol | undefined { + if (location && location.kind === SyntaxKind.ShorthandPropertyAssignment) { + return resolveEntityName((location as ShorthandPropertyAssignment).name, SymbolFlags.Value | SymbolFlags.Alias); + } + return undefined; + } + + /** Returns the target of an export specifier without following aliases */ + function getExportSpecifierLocalTargetSymbol(node: ExportSpecifier | Identifier): Symbol | undefined { + if (isExportSpecifier(node)) { + const name = node.propertyName || node.name; + return node.parent.parent.moduleSpecifier ? + getExternalModuleMember(node.parent.parent, node) : + name.kind === SyntaxKind.StringLiteral ? undefined : // Skip for invalid syntax like this: export { "x" } + resolveEntityName(name, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); + } + else { + return resolveEntityName(node, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); + } + } + + function getTypeOfNode(node: Node): Type { + if (isSourceFile(node) && !isExternalModule(node)) { + return errorType; + } + + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return errorType; + } + + const classDecl = tryGetClassImplementingOrExtendingExpressionWithTypeArguments(node); + const classType = classDecl && getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(classDecl.class)); + if (isPartOfTypeNode(node)) { + const typeFromTypeNode = getTypeFromTypeNode(node as TypeNode); + return classType ? getTypeWithThisArgument(typeFromTypeNode, classType.thisType) : typeFromTypeNode; + } + + if (isExpressionNode(node)) { + return getRegularTypeOfExpression(node as Expression); + } + + if (classType && !classDecl.isImplements) { + // A SyntaxKind.ExpressionWithTypeArguments is considered a type node, except when it occurs in the + // extends clause of a class. We handle that case here. + const baseType = firstOrUndefined(getBaseTypes(classType)); + return baseType ? getTypeWithThisArgument(baseType, classType.thisType) : errorType; + } + + if (isTypeDeclaration(node)) { + // In this case, we call getSymbolOfNode instead of getSymbolAtLocation because it is a declaration + const symbol = getSymbolOfDeclaration(node); + return getDeclaredTypeOfSymbol(symbol); + } + + if (isTypeDeclarationName(node)) { + const symbol = getSymbolAtLocation(node); + return symbol ? getDeclaredTypeOfSymbol(symbol) : errorType; + } + + if (isBindingElement(node)) { + return getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ true, CheckMode.Normal) || errorType; + } + + if (isDeclaration(node)) { + // In this case, we call getSymbolOfNode instead of getSymbolAtLocation because it is a declaration + const symbol = getSymbolOfDeclaration(node); + return symbol ? getTypeOfSymbol(symbol) : errorType; + } + + if (isDeclarationNameOrImportPropertyName(node)) { + const symbol = getSymbolAtLocation(node); + if (symbol) { + return getTypeOfSymbol(symbol); + } + return errorType; + } + + if (isBindingPattern(node)) { + return getTypeForVariableLikeDeclaration(node.parent, /*includeOptionality*/ true, CheckMode.Normal) || errorType; + } + + if (isInRightSideOfImportOrExportAssignment(node as Identifier)) { + const symbol = getSymbolAtLocation(node); + if (symbol) { + const declaredType = getDeclaredTypeOfSymbol(symbol); + return !isErrorType(declaredType) ? declaredType : getTypeOfSymbol(symbol); + } + } + + if (isMetaProperty(node.parent) && node.parent.keywordToken === node.kind) { + return checkMetaPropertyKeyword(node.parent); + } + + if (isImportAttributes(node)) { + return getGlobalImportAttributesType(/*reportErrors*/ false); + } + + return errorType; + } + + // Gets the type of object literal or array literal of destructuring assignment. + // { a } from + // for ( { a } of elems) { + // } + // [ a ] from + // [a] = [ some array ...] + function getTypeOfAssignmentPattern(expr: AssignmentPattern): Type | undefined { + Debug.assert(expr.kind === SyntaxKind.ObjectLiteralExpression || expr.kind === SyntaxKind.ArrayLiteralExpression); + // If this is from "for of" + // for ( { a } of elems) { + // } + if (expr.parent.kind === SyntaxKind.ForOfStatement) { + const iteratedType = checkRightHandSideOfForOf(expr.parent as ForOfStatement); + return checkDestructuringAssignment(expr, iteratedType || errorType); + } + // If this is from "for" initializer + // for ({a } = elems[0];.....) { } + if (expr.parent.kind === SyntaxKind.BinaryExpression) { + const iteratedType = getTypeOfExpression((expr.parent as BinaryExpression).right); + return checkDestructuringAssignment(expr, iteratedType || errorType); + } + // If this is from nested object binding pattern + // for ({ skills: { primary, secondary } } = multiRobot, i = 0; i < 1; i++) { + if (expr.parent.kind === SyntaxKind.PropertyAssignment) { + const node = cast(expr.parent.parent, isObjectLiteralExpression); + const typeOfParentObjectLiteral = getTypeOfAssignmentPattern(node) || errorType; + const propertyIndex = indexOfNode(node.properties, expr.parent); + return checkObjectLiteralDestructuringPropertyAssignment(node, typeOfParentObjectLiteral, propertyIndex); + } + // Array literal assignment - array destructuring pattern + const node = cast(expr.parent, isArrayLiteralExpression); + // [{ property1: p1, property2 }] = elems; + const typeOfArrayLiteral = getTypeOfAssignmentPattern(node) || errorType; + const elementType = checkIteratedTypeOrElementType(IterationUse.Destructuring, typeOfArrayLiteral, undefinedType, expr.parent) || errorType; + return checkArrayLiteralDestructuringElementAssignment(node, typeOfArrayLiteral, node.elements.indexOf(expr), elementType); + } + + // Gets the property symbol corresponding to the property in destructuring assignment + // 'property1' from + // for ( { property1: a } of elems) { + // } + // 'property1' at location 'a' from: + // [a] = [ property1, property2 ] + function getPropertySymbolOfDestructuringAssignment(location: Identifier) { + // Get the type of the object or array literal and then look for property of given name in the type + const typeOfObjectLiteral = getTypeOfAssignmentPattern(cast(location.parent.parent, isAssignmentPattern)); + return typeOfObjectLiteral && getPropertyOfType(typeOfObjectLiteral, location.escapedText); + } + + function getRegularTypeOfExpression(expr: Expression): Type { + if (isRightSideOfQualifiedNameOrPropertyAccess(expr)) { + expr = expr.parent as Expression; + } + return getRegularTypeOfLiteralType(getTypeOfExpression(expr)); + } + + /** + * Gets either the static or instance type of a class element, based on + * whether the element is declared as "static". + */ + function getParentTypeOfClassElement(node: ClassElement) { + const classSymbol = getSymbolOfNode(node.parent)!; + return isStatic(node) + ? getTypeOfSymbol(classSymbol) + : getDeclaredTypeOfSymbol(classSymbol); + } + + function getClassElementPropertyKeyType(element: ClassElement) { + const name = element.name!; + switch (name.kind) { + case SyntaxKind.Identifier: + return getStringLiteralType(idText(name)); + case SyntaxKind.NumericLiteral: + case SyntaxKind.StringLiteral: + return getStringLiteralType(name.text); + case SyntaxKind.ComputedPropertyName: + const nameType = checkComputedPropertyName(name); + return isTypeAssignableToKind(nameType, TypeFlags.ESSymbolLike) ? nameType : stringType; + default: + return Debug.fail("Unsupported property name."); + } + } + + // Return the list of properties of the given type, augmented with properties from Function + // if the type has call or construct signatures + function getAugmentedPropertiesOfType(type: Type): Symbol[] { + type = getApparentType(type); + const propsByName = createSymbolTable(getPropertiesOfType(type)); + const functionType = getSignaturesOfType(type, SignatureKind.Call).length ? globalCallableFunctionType : + getSignaturesOfType(type, SignatureKind.Construct).length ? globalNewableFunctionType : + undefined; + if (functionType) { + forEach(getPropertiesOfType(functionType), p => { + if (!propsByName.has(p.escapedName)) { + propsByName.set(p.escapedName, p); + } + }); + } + return getNamedMembers(propsByName); + } + + function typeHasCallOrConstructSignatures(type: Type): boolean { + return getSignaturesOfType(type, SignatureKind.Call).length !== 0 || getSignaturesOfType(type, SignatureKind.Construct).length !== 0; + } + + function getRootSymbols(symbol: Symbol): readonly Symbol[] { + const roots = getImmediateRootSymbols(symbol); + return roots ? flatMap(roots, getRootSymbols) : [symbol]; + } + function getImmediateRootSymbols(symbol: Symbol): readonly Symbol[] | undefined { + if (getCheckFlags(symbol) & CheckFlags.Synthetic) { + return mapDefined(getSymbolLinks(symbol).containingType!.types, type => getPropertyOfType(type, symbol.escapedName)); + } + else if (symbol.flags & SymbolFlags.Transient) { + const { links: { leftSpread, rightSpread, syntheticOrigin } } = symbol as TransientSymbol; + return leftSpread ? [leftSpread, rightSpread!] + : syntheticOrigin ? [syntheticOrigin] + : singleElementArray(tryGetTarget(symbol)); + } + return undefined; + } + function tryGetTarget(symbol: Symbol): Symbol | undefined { + let target: Symbol | undefined; + let next: Symbol | undefined = symbol; + while (next = getSymbolLinks(next).target) { + target = next; + } + return target; + } + + // Emitter support + + function isArgumentsLocalBinding(nodeIn: Identifier): boolean { + // Note: does not handle isShorthandPropertyAssignment (and probably a few more) + if (isGeneratedIdentifier(nodeIn)) return false; + const node = getParseTreeNode(nodeIn, isIdentifier); + if (!node) return false; + const parent = node.parent; + if (!parent) return false; + const isPropertyName = (isPropertyAccessExpression(parent) + || isPropertyAssignment(parent)) + && parent.name === node; + return !isPropertyName && getReferencedValueSymbol(node) === argumentsSymbol; + } + + function isNameOfModuleOrEnumDeclaration(node: Identifier) { + return isModuleOrEnumDeclaration(node.parent) && node === node.parent.name; + } + + // When resolved as an expression identifier, if the given node references an exported entity, return the declaration + // node of the exported entity's container. Otherwise, return undefined. + function getReferencedExportContainer(nodeIn: Identifier, prefixLocals?: boolean): SourceFile | ModuleDeclaration | EnumDeclaration | undefined { + const node = getParseTreeNode(nodeIn, isIdentifier); + if (node) { + // When resolving the export container for the name of a module or enum + // declaration, we need to start resolution at the declaration's container. + // Otherwise, we could incorrectly resolve the export container as the + // declaration if it contains an exported member with the same name. + let symbol = getReferencedValueSymbol(node, /*startInDeclarationContainer*/ isNameOfModuleOrEnumDeclaration(node)); + if (symbol) { + if (symbol.flags & SymbolFlags.ExportValue) { + // If we reference an exported entity within the same module declaration, then whether + // we prefix depends on the kind of entity. SymbolFlags.ExportHasLocal encompasses all the + // kinds that we do NOT prefix. + const exportSymbol = getMergedSymbol(symbol.exportSymbol!); + if (!prefixLocals && exportSymbol.flags & SymbolFlags.ExportHasLocal && !(exportSymbol.flags & SymbolFlags.Variable)) { + return undefined; + } + symbol = exportSymbol; + } + const parentSymbol = getParentOfSymbol(symbol); + if (parentSymbol) { + if (parentSymbol.flags & SymbolFlags.ValueModule && parentSymbol.valueDeclaration?.kind === SyntaxKind.SourceFile) { + const symbolFile = parentSymbol.valueDeclaration as SourceFile; + const referenceFile = getSourceFileOfNode(node); + // If `node` accesses an export and that export isn't in the same file, then symbol is a namespace export, so return undefined. + const symbolIsUmdExport = symbolFile !== referenceFile; + return symbolIsUmdExport ? undefined : symbolFile; + } + return findAncestor(node.parent, (n): n is ModuleDeclaration | EnumDeclaration => isModuleOrEnumDeclaration(n) && getSymbolOfDeclaration(n) === parentSymbol); + } + } + } + } + + // When resolved as an expression identifier, if the given node references an import, return the declaration of + // that import. Otherwise, return undefined. + function getReferencedImportDeclaration(nodeIn: Identifier): Declaration | undefined { + const specifier = getIdentifierGeneratedImportReference(nodeIn); + if (specifier) { + return specifier; + } + const node = getParseTreeNode(nodeIn, isIdentifier); + if (node) { + const symbol = getReferencedValueOrAliasSymbol(node); + + // We should only get the declaration of an alias if there isn't a local value + // declaration for the symbol + if (isNonLocalAlias(symbol, /*excludes*/ SymbolFlags.Value) && !getTypeOnlyAliasDeclaration(symbol, SymbolFlags.Value)) { + return getDeclarationOfAliasSymbol(symbol); + } + } + + return undefined; + } + + function isSymbolOfDestructuredElementOfCatchBinding(symbol: Symbol) { + return symbol.valueDeclaration + && isBindingElement(symbol.valueDeclaration) + && walkUpBindingElementsAndPatterns(symbol.valueDeclaration).parent.kind === SyntaxKind.CatchClause; + } + + function isSymbolOfDeclarationWithCollidingName(symbol: Symbol): boolean { + if (symbol.flags & SymbolFlags.BlockScoped && symbol.valueDeclaration && !isSourceFile(symbol.valueDeclaration)) { + const links = getSymbolLinks(symbol); + if (links.isDeclarationWithCollidingName === undefined) { + const container = getEnclosingBlockScopeContainer(symbol.valueDeclaration); + if (isStatementWithLocals(container) || isSymbolOfDestructuredElementOfCatchBinding(symbol)) { + if (resolveName(container.parent, symbol.escapedName, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)) { + // redeclaration - always should be renamed + links.isDeclarationWithCollidingName = true; + } + else if (hasNodeCheckFlag(symbol.valueDeclaration, NodeCheckFlags.CapturedBlockScopedBinding)) { + // binding is captured in the function + // should be renamed if: + // - binding is not top level - top level bindings never collide with anything + // AND + // - binding is not declared in loop, should be renamed to avoid name reuse across siblings + // let a, b + // { let x = 1; a = () => x; } + // { let x = 100; b = () => x; } + // console.log(a()); // should print '1' + // console.log(b()); // should print '100' + // OR + // - binding is declared inside loop but not in inside initializer of iteration statement or directly inside loop body + // * variables from initializer are passed to rewritten loop body as parameters so they are not captured directly + // * variables that are declared immediately in loop body will become top level variable after loop is rewritten and thus + // they will not collide with anything + const isDeclaredInLoop = hasNodeCheckFlag(symbol.valueDeclaration, NodeCheckFlags.BlockScopedBindingInLoop); + const inLoopInitializer = isIterationStatement(container, /*lookInLabeledStatements*/ false); + const inLoopBodyBlock = container.kind === SyntaxKind.Block && isIterationStatement(container.parent, /*lookInLabeledStatements*/ false); + + links.isDeclarationWithCollidingName = !isBlockScopedContainerTopLevel(container) && (!isDeclaredInLoop || (!inLoopInitializer && !inLoopBodyBlock)); + } + else { + links.isDeclarationWithCollidingName = false; + } + } + } + return links.isDeclarationWithCollidingName!; + } + return false; + } + + // When resolved as an expression identifier, if the given node references a nested block scoped entity with + // a name that either hides an existing name or might hide it when compiled downlevel, + // return the declaration of that entity. Otherwise, return undefined. + function getReferencedDeclarationWithCollidingName(nodeIn: Identifier): Declaration | undefined { + if (!isGeneratedIdentifier(nodeIn)) { + const node = getParseTreeNode(nodeIn, isIdentifier); + if (node) { + const symbol = getReferencedValueSymbol(node); + if (symbol && isSymbolOfDeclarationWithCollidingName(symbol)) { + return symbol.valueDeclaration; + } + } + } + + return undefined; + } + + // Return true if the given node is a declaration of a nested block scoped entity with a name that either hides an + // existing name or might hide a name when compiled downlevel + function isDeclarationWithCollidingName(nodeIn: Declaration): boolean { + const node = getParseTreeNode(nodeIn, isDeclaration); + if (node) { + const symbol = getSymbolOfDeclaration(node); + if (symbol) { + return isSymbolOfDeclarationWithCollidingName(symbol); + } + } + + return false; + } + + function isValueAliasDeclaration(node: Node): boolean { + Debug.assert(canCollectSymbolAliasAccessabilityData); + switch (node.kind) { + case SyntaxKind.ImportEqualsDeclaration: + return isAliasResolvedToValue(getSymbolOfDeclaration(node as ImportEqualsDeclaration)); + case SyntaxKind.ImportClause: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportSpecifier: + case SyntaxKind.ExportSpecifier: + const symbol = getSymbolOfDeclaration(node as ImportClause | NamespaceImport | ImportSpecifier | ExportSpecifier); + return !!symbol && isAliasResolvedToValue(symbol, /*excludeTypeOnlyValues*/ true); + case SyntaxKind.ExportDeclaration: + const exportClause = (node as ExportDeclaration).exportClause; + return !!exportClause && ( + isNamespaceExport(exportClause) || + some(exportClause.elements, isValueAliasDeclaration) + ); + case SyntaxKind.ExportAssignment: + return (node as ExportAssignment).expression && (node as ExportAssignment).expression.kind === SyntaxKind.Identifier ? + isAliasResolvedToValue(getSymbolOfDeclaration(node as ExportAssignment), /*excludeTypeOnlyValues*/ true) : + true; + } + return false; + } + + function isTopLevelValueImportEqualsWithEntityName(nodeIn: ImportEqualsDeclaration): boolean { + const node = getParseTreeNode(nodeIn, isImportEqualsDeclaration); + if (node === undefined || node.parent.kind !== SyntaxKind.SourceFile || !isInternalModuleImportEqualsDeclaration(node)) { + // parent is not source file or it is not reference to internal module + return false; + } + + const isValue = isAliasResolvedToValue(getSymbolOfDeclaration(node)); + return isValue && node.moduleReference && !nodeIsMissing(node.moduleReference); + } + + function isAliasResolvedToValue(symbol: Symbol | undefined, excludeTypeOnlyValues?: boolean): boolean { + if (!symbol) { + return false; + } + const container = getSourceFileOfNode(symbol.valueDeclaration); + const fileSymbol = container && getSymbolOfDeclaration(container); + // Ensures cjs export assignment is setup, since this symbol may point at, and merge with, the file itself. + // If we don't, the merge may not have yet occured, and the flags check below will be missing flags that + // are added as a result of the merge. + void resolveExternalModuleSymbol(fileSymbol); + const target = getExportSymbolOfValueSymbolIfExported(resolveAlias(symbol)); + if (target === unknownSymbol) { + return !excludeTypeOnlyValues || !getTypeOnlyAliasDeclaration(symbol); + } + // const enums and modules that contain only const enums are not considered values from the emit perspective + // unless 'preserveConstEnums' option is set to true + return !!(getSymbolFlags(symbol, excludeTypeOnlyValues, /*excludeLocalMeanings*/ true) & SymbolFlags.Value) && + (shouldPreserveConstEnums(compilerOptions) || !isConstEnumOrConstEnumOnlyModule(target)); + } + + function isConstEnumOrConstEnumOnlyModule(s: Symbol): boolean { + return isConstEnumSymbol(s) || !!s.constEnumOnlyModule; + } + + function isReferencedAliasDeclaration(node: Node, checkChildren?: boolean): boolean { + Debug.assert(canCollectSymbolAliasAccessabilityData); + if (isAliasSymbolDeclaration(node)) { + const symbol = getSymbolOfDeclaration(node as Declaration); + const links = symbol && getSymbolLinks(symbol); + if (links?.referenced) { + return true; + } + const target = getSymbolLinks(symbol).aliasTarget; + if ( + target && getEffectiveModifierFlags(node) & ModifierFlags.Export && + getSymbolFlags(target) & SymbolFlags.Value && + (shouldPreserveConstEnums(compilerOptions) || !isConstEnumOrConstEnumOnlyModule(target)) + ) { + // An `export import ... =` of a value symbol is always considered referenced + return true; + } + } + + if (checkChildren) { + return !!forEachChild(node, node => isReferencedAliasDeclaration(node, checkChildren)); + } + return false; + } + + function isImplementationOfOverload(node: SignatureDeclaration) { + if (nodeIsPresent((node as FunctionLikeDeclaration).body)) { + if (isGetAccessor(node) || isSetAccessor(node)) return false; // Get or set accessors can never be overload implementations, but can have up to 2 signatures + const symbol = getSymbolOfDeclaration(node); + const signaturesOfSymbol = getSignaturesOfSymbol(symbol); + // If this function body corresponds to function with multiple signature, it is implementation of overload + // e.g.: function foo(a: string): string; + // function foo(a: number): number; + // function foo(a: any) { // This is implementation of the overloads + // return a; + // } + return signaturesOfSymbol.length > 1 || + // If there is single signature for the symbol, it is overload if that signature isn't coming from the node + // e.g.: function foo(a: string): string; + // function foo(a: any) { // This is implementation of the overloads + // return a; + // } + (signaturesOfSymbol.length === 1 && signaturesOfSymbol[0].declaration !== node); + } + return false; + } + + function declaredParameterTypeContainsUndefined(parameter: ParameterDeclaration | JSDocParameterTag) { + const typeNode = getNonlocalEffectiveTypeAnnotationNode(parameter); + if (!typeNode) return false; + const type = getTypeFromTypeNode(typeNode); + return containsUndefinedType(type); + } + function requiresAddingImplicitUndefined(parameter: ParameterDeclaration | JSDocParameterTag) { + return (isRequiredInitializedParameter(parameter) || isOptionalUninitializedParameterProperty(parameter)) && !declaredParameterTypeContainsUndefined(parameter); + } + + function isRequiredInitializedParameter(parameter: ParameterDeclaration | JSDocParameterTag): boolean { + return !!strictNullChecks && + !isOptionalParameter(parameter) && + !isJSDocParameterTag(parameter) && + !!parameter.initializer && + !hasSyntacticModifier(parameter, ModifierFlags.ParameterPropertyModifier); + } + + function isOptionalUninitializedParameterProperty(parameter: ParameterDeclaration | JSDocParameterTag) { + return strictNullChecks && + isOptionalParameter(parameter) && + (isJSDocParameterTag(parameter) || !parameter.initializer) && + hasSyntacticModifier(parameter, ModifierFlags.ParameterPropertyModifier); + } + + function isExpandoFunctionDeclaration(node: Declaration): boolean { + const declaration = getParseTreeNode(node, (n): n is FunctionDeclaration | VariableDeclaration => isFunctionDeclaration(n) || isVariableDeclaration(n)); + if (!declaration) { + return false; + } + let symbol: Symbol | undefined; + if (isVariableDeclaration(declaration)) { + if (declaration.type || (!isInJSFile(declaration) && !isVarConstLike(declaration))) { + return false; + } + const initializer = getDeclaredExpandoInitializer(declaration); + if (!initializer || !canHaveSymbol(initializer)) { + return false; + } + symbol = getSymbolOfDeclaration(initializer); + } + else { + symbol = getSymbolOfDeclaration(declaration); + } + if (!symbol || !(symbol.flags & SymbolFlags.Function | SymbolFlags.Variable)) { + return false; + } + return !!forEachEntry(getExportsOfSymbol(symbol), p => p.flags & SymbolFlags.Value && isExpandoPropertyDeclaration(p.valueDeclaration)); + } + + function getPropertiesOfContainerFunction(node: Declaration): Symbol[] { + const declaration = getParseTreeNode(node, isFunctionDeclaration); + if (!declaration) { + return emptyArray; + } + const symbol = getSymbolOfDeclaration(declaration); + return symbol && getPropertiesOfType(getTypeOfSymbol(symbol)) || emptyArray; + } + + function getNodeCheckFlags(node: Node): NodeCheckFlags { + const nodeId = node.id || 0; + if (nodeId < 0 || nodeId >= nodeLinks.length) return 0; + return nodeLinks[nodeId]?.flags || 0; + } + + function hasNodeCheckFlag(node: Node, flag: LazyNodeCheckFlags) { + calculateNodeCheckFlagWorker(node, flag); + return !!(getNodeCheckFlags(node) & flag); + } + + function calculateNodeCheckFlagWorker(node: Node, flag: LazyNodeCheckFlags) { + if (!compilerOptions.noCheck && canIncludeBindAndCheckDiagnostics(getSourceFileOfNode(node), compilerOptions)) { + // Unless noCheck is passed, assume calculation of node check flags has been done eagerly. + // This saves needing to mark up where in the eager traversal certain results are "done", + // just to reconcile the eager and lazy results. This wouldn't be hard if an eager typecheck + // was actually an in-order traversal, but it isn't - some nodes are deferred, and so don't + // have these node check flags calculated until that deferral is completed. As an example, + // in concept, we could consider a class that we've called `checkSourceElement` on as having had + // these flags calculated, but since the method bodies are deferred, we actually can't set the + // flags as having been calculated until that deferral is completed. + // The downside to this either/or approach to eager or lazy calculation is that we can't combine + // a partial eager traversal and lazy calculation for the missing bits, and there's a bit of + // overlap in functionality. This isn't a huge loss for any usecases today, but would be nice + // alongside language service partial file checking and editor-triggered emit. + return; + } + const links = getNodeLinks(node); + if (links.calculatedFlags & flag) { + return; + } + // This is only the set of `NodeCheckFlags` our emitter actually looks for, not all of them + switch (flag) { + case NodeCheckFlags.SuperInstance: + case NodeCheckFlags.SuperStatic: + return checkSingleSuperExpression(node); + case NodeCheckFlags.MethodWithSuperPropertyAccessInAsync: + case NodeCheckFlags.MethodWithSuperPropertyAssignmentInAsync: + case NodeCheckFlags.ContainsSuperPropertyInStaticInitializer: + return checkChildSuperExpressions(node); + case NodeCheckFlags.CaptureArguments: + case NodeCheckFlags.ContainsCapturedBlockScopeBinding: + case NodeCheckFlags.NeedsLoopOutParameter: + case NodeCheckFlags.ContainsConstructorReference: + return checkChildIdentifiers(node); + case NodeCheckFlags.ConstructorReference: + return checkSingleIdentifier(node); + case NodeCheckFlags.LoopWithCapturedBlockScopedBinding: + case NodeCheckFlags.BlockScopedBindingInLoop: + case NodeCheckFlags.CapturedBlockScopedBinding: + return checkContainingBlockScopeBindingUses(node); + default: + return Debug.assertNever(flag, `Unhandled node check flag calculation: ${Debug.formatNodeCheckFlags(flag)}`); + } + + function forEachNodeRecursively(root: Node, cb: (node: Node, parent: Node) => T | "skip" | undefined): T | undefined { + const rootResult = cb(root, root.parent); + if (rootResult === "skip") return undefined; + if (rootResult) return rootResult; + return forEachChildRecursively(root, cb); + } + + function checkSuperExpressions(node: Node) { + const links = getNodeLinks(node); + if (links.calculatedFlags & flag) return "skip"; + links.calculatedFlags |= NodeCheckFlags.MethodWithSuperPropertyAccessInAsync | NodeCheckFlags.MethodWithSuperPropertyAssignmentInAsync | NodeCheckFlags.ContainsSuperPropertyInStaticInitializer; + checkSingleSuperExpression(node); + return undefined; + } + + function checkChildSuperExpressions(node: Node) { + forEachNodeRecursively(node, checkSuperExpressions); + } + + function checkSingleSuperExpression(node: Node) { + const nodeLinks = getNodeLinks(node); // This is called on sub-nodes of the original input, make sure we set `calculatedFlags` on the correct node + nodeLinks.calculatedFlags |= NodeCheckFlags.SuperInstance | NodeCheckFlags.SuperStatic; // Yes, we set this on non-applicable nodes, so we can entirely skip the traversal on future calls + if (node.kind === SyntaxKind.SuperKeyword) { + checkSuperExpression(node); + } + } + + function checkIdentifiers(node: Node) { + const links = getNodeLinks(node); + if (links.calculatedFlags & flag) return "skip"; + links.calculatedFlags |= NodeCheckFlags.CaptureArguments | NodeCheckFlags.ContainsCapturedBlockScopeBinding | NodeCheckFlags.NeedsLoopOutParameter | NodeCheckFlags.ContainsConstructorReference; + checkSingleIdentifier(node); + return undefined; + } + + function checkChildIdentifiers(node: Node) { + forEachNodeRecursively(node, checkIdentifiers); + } + + function checkSingleIdentifier(node: Node) { + const nodeLinks = getNodeLinks(node); + nodeLinks.calculatedFlags |= NodeCheckFlags.ConstructorReference | NodeCheckFlags.CapturedBlockScopedBinding | NodeCheckFlags.BlockScopedBindingInLoop; + if (isIdentifier(node) && isExpressionNode(node) && !(isPropertyAccessExpression(node.parent) && node.parent.name === node)) { + const s = getSymbolAtLocation(node, /*ignoreErrors*/ true); + if (s && s !== unknownSymbol) { + checkIdentifierCalculateNodeCheckFlags(node, s); + } + } + } + + function checkBlockScopeBindings(node: Node) { + const links = getNodeLinks(node); + if (links.calculatedFlags & flag) return "skip"; + links.calculatedFlags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding | NodeCheckFlags.BlockScopedBindingInLoop | NodeCheckFlags.CapturedBlockScopedBinding; + checkSingleBlockScopeBinding(node); + return undefined; + } + + function checkContainingBlockScopeBindingUses(node: Node) { + const scope = getEnclosingBlockScopeContainer(isDeclarationName(node) ? node.parent : node); + forEachNodeRecursively(scope, checkBlockScopeBindings); + } + + function checkSingleBlockScopeBinding(node: Node) { + checkSingleIdentifier(node); + if (isComputedPropertyName(node)) { + checkComputedPropertyName(node); + } + if (isPrivateIdentifier(node) && isClassElement(node.parent)) { + setNodeLinksForPrivateIdentifierScope(node.parent as PropertyDeclaration | PropertySignature | MethodDeclaration | MethodSignature | AccessorDeclaration); + } + } + } + + function getEnumMemberValue(node: EnumMember): EvaluatorResult { + computeEnumMemberValues(node.parent); + return getNodeLinks(node).enumMemberValue ?? evaluatorResult(/*value*/ undefined); + } + + function canHaveConstantValue(node: Node): node is EnumMember | AccessExpression { + switch (node.kind) { + case SyntaxKind.EnumMember: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + return true; + } + return false; + } + + function getConstantValue(node: EnumMember | AccessExpression): string | number | undefined { + if (node.kind === SyntaxKind.EnumMember) { + return getEnumMemberValue(node).value; + } + + if (!getNodeLinks(node).resolvedSymbol) { + void checkExpressionCached(node); // ensure cached resolved symbol is set + } + const symbol = getNodeLinks(node).resolvedSymbol || (isEntityNameExpression(node) ? resolveEntityName(node, SymbolFlags.Value, /*ignoreErrors*/ true) : undefined); + if (symbol && (symbol.flags & SymbolFlags.EnumMember)) { + // inline property\index accesses only for const enums + const member = symbol.valueDeclaration as EnumMember; + if (isEnumConst(member.parent)) { + return getEnumMemberValue(member).value; + } + } + + return undefined; + } + + function isFunctionType(type: Type): boolean { + return !!(type.flags & TypeFlags.Object) && getSignaturesOfType(type, SignatureKind.Call).length > 0; + } + + function getTypeReferenceSerializationKind(typeNameIn: EntityName, location?: Node): TypeReferenceSerializationKind { + // ensure both `typeName` and `location` are parse tree nodes. + const typeName = getParseTreeNode(typeNameIn, isEntityName); + if (!typeName) return TypeReferenceSerializationKind.Unknown; + + if (location) { + location = getParseTreeNode(location); + if (!location) return TypeReferenceSerializationKind.Unknown; + } + + // Resolve the symbol as a value to ensure the type can be reached at runtime during emit. + let isTypeOnly = false; + if (isQualifiedName(typeName)) { + const rootValueSymbol = resolveEntityName(getFirstIdentifier(typeName), SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location); + isTypeOnly = !!rootValueSymbol?.declarations?.every(isTypeOnlyImportOrExportDeclaration); + } + const valueSymbol = resolveEntityName(typeName, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location); + const resolvedValueSymbol = valueSymbol && valueSymbol.flags & SymbolFlags.Alias ? resolveAlias(valueSymbol) : valueSymbol; + isTypeOnly ||= !!(valueSymbol && getTypeOnlyAliasDeclaration(valueSymbol, SymbolFlags.Value)); + + // Resolve the symbol as a type so that we can provide a more useful hint for the type serializer. + const typeSymbol = resolveEntityName(typeName, SymbolFlags.Type, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location); + const resolvedTypeSymbol = typeSymbol && typeSymbol.flags & SymbolFlags.Alias ? resolveAlias(typeSymbol) : typeSymbol; + + // In case the value symbol can't be resolved (e.g. because of missing declarations), use type symbol for reachability check. + if (!valueSymbol) { + isTypeOnly ||= !!(typeSymbol && getTypeOnlyAliasDeclaration(typeSymbol, SymbolFlags.Type)); + } + + if (resolvedValueSymbol && resolvedValueSymbol === resolvedTypeSymbol) { + const globalPromiseSymbol = getGlobalPromiseConstructorSymbol(/*reportErrors*/ false); + if (globalPromiseSymbol && resolvedValueSymbol === globalPromiseSymbol) { + return TypeReferenceSerializationKind.Promise; + } + + const constructorType = getTypeOfSymbol(resolvedValueSymbol); + if (constructorType && isConstructorType(constructorType)) { + return isTypeOnly ? TypeReferenceSerializationKind.TypeWithCallSignature : TypeReferenceSerializationKind.TypeWithConstructSignatureAndValue; + } + } + + // We might not be able to resolve type symbol so use unknown type in that case (eg error case) + if (!resolvedTypeSymbol) { + return isTypeOnly ? TypeReferenceSerializationKind.ObjectType : TypeReferenceSerializationKind.Unknown; + } + const type = getDeclaredTypeOfSymbol(resolvedTypeSymbol); + if (isErrorType(type)) { + return isTypeOnly ? TypeReferenceSerializationKind.ObjectType : TypeReferenceSerializationKind.Unknown; + } + else if (type.flags & TypeFlags.AnyOrUnknown) { + return TypeReferenceSerializationKind.ObjectType; + } + else if (isTypeAssignableToKind(type, TypeFlags.Void | TypeFlags.Nullable | TypeFlags.Never)) { + return TypeReferenceSerializationKind.VoidNullableOrNeverType; + } + else if (isTypeAssignableToKind(type, TypeFlags.BooleanLike)) { + return TypeReferenceSerializationKind.BooleanType; + } + else if (isTypeAssignableToKind(type, TypeFlags.NumberLike)) { + return TypeReferenceSerializationKind.NumberLikeType; + } + else if (isTypeAssignableToKind(type, TypeFlags.BigIntLike)) { + return TypeReferenceSerializationKind.BigIntLikeType; + } + else if (isTypeAssignableToKind(type, TypeFlags.StringLike)) { + return TypeReferenceSerializationKind.StringLikeType; + } + else if (isTupleType(type)) { + return TypeReferenceSerializationKind.ArrayLikeType; + } + else if (isTypeAssignableToKind(type, TypeFlags.ESSymbolLike)) { + return TypeReferenceSerializationKind.ESSymbolType; + } + else if (isFunctionType(type)) { + return TypeReferenceSerializationKind.TypeWithCallSignature; + } + else if (isArrayType(type)) { + return TypeReferenceSerializationKind.ArrayLikeType; + } + else { + return TypeReferenceSerializationKind.ObjectType; + } + } + + function createTypeOfDeclaration(declarationIn: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) { + const declaration = getParseTreeNode(declarationIn, isVariableLikeOrAccessor); + if (!declaration) { + return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode; + } + // Get type of the symbol if this is the valid symbol otherwise get type at location + const symbol = getSymbolOfDeclaration(declaration); + const type = symbol && !(symbol.flags & (SymbolFlags.TypeLiteral | SymbolFlags.Signature)) + ? getWidenedLiteralType(getTypeOfSymbol(symbol)) + : errorType; + + return nodeBuilder.serializeTypeForDeclaration(declaration, type, symbol, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker); + } + + type DeclarationWithPotentialInnerNodeReuse = + | SignatureDeclaration + | JSDocSignature + | AccessorDeclaration + | VariableLikeDeclaration + | PropertyAccessExpression + | ExportAssignment; + + function isDeclarationWithPossibleInnerTypeNodeReuse(declaration: Declaration): declaration is DeclarationWithPotentialInnerNodeReuse { + return isFunctionLike(declaration) || isExportAssignment(declaration) || isVariableLike(declaration); + } + + function getAllAccessorDeclarationsForDeclaration(accessor: AccessorDeclaration): AllAccessorDeclarations { + accessor = getParseTreeNode(accessor, isGetOrSetAccessorDeclaration)!; // TODO: GH#18217 + const otherKind = accessor.kind === SyntaxKind.SetAccessor ? SyntaxKind.GetAccessor : SyntaxKind.SetAccessor; + const otherAccessor = getDeclarationOfKind(getSymbolOfDeclaration(accessor), otherKind); + const firstAccessor = otherAccessor && (otherAccessor.pos < accessor.pos) ? otherAccessor : accessor; + const secondAccessor = otherAccessor && (otherAccessor.pos < accessor.pos) ? accessor : otherAccessor; + const setAccessor = accessor.kind === SyntaxKind.SetAccessor ? accessor : otherAccessor as SetAccessorDeclaration; + const getAccessor = accessor.kind === SyntaxKind.GetAccessor ? accessor : otherAccessor as GetAccessorDeclaration; + return { + firstAccessor, + secondAccessor, + setAccessor, + getAccessor, + }; + } + + function getPossibleTypeNodeReuseExpression(declaration: DeclarationWithPotentialInnerNodeReuse) { + return isFunctionLike(declaration) && !isSetAccessor(declaration) + ? getSingleReturnExpression(declaration) + : isExportAssignment(declaration) + ? declaration.expression + : !!(declaration as HasInitializer).initializer + ? (declaration as HasInitializer & typeof declaration).initializer + : isParameter(declaration) && isSetAccessor(declaration.parent) + ? getSingleReturnExpression(getAllAccessorDeclarationsForDeclaration(declaration.parent).getAccessor) + : undefined; + } + + function getSingleReturnExpression(declaration: SignatureDeclaration | undefined): Expression | undefined { + let candidateExpr: Expression | undefined; + if (declaration && !nodeIsMissing((declaration as FunctionLikeDeclaration).body)) { + if (getFunctionFlags(declaration) & FunctionFlags.AsyncGenerator) return undefined; + const body = (declaration as FunctionLikeDeclaration).body; + if (body && isBlock(body)) { + forEachReturnStatement(body, s => { + if (!candidateExpr) { + candidateExpr = s.expression; + } + else { + candidateExpr = undefined; + return true; + } + }); + } + else { + candidateExpr = body; + } + } + return candidateExpr; + } + + function createReturnTypeOfSignatureDeclaration(signatureDeclarationIn: SignatureDeclaration, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) { + const signatureDeclaration = getParseTreeNode(signatureDeclarationIn, isFunctionLike); + if (!signatureDeclaration) { + return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode; + } + return nodeBuilder.serializeReturnTypeForSignature(getSignatureFromDeclaration(signatureDeclaration), enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker); + } + + function createTypeOfExpression(exprIn: Expression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) { + const expr = getParseTreeNode(exprIn, isExpression); + if (!expr) { + return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode; + } + const type = getWidenedType(getRegularTypeOfExpression(expr)); + return nodeBuilder.expressionOrTypeToTypeNode(expr, type, /*addUndefined*/ undefined, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker); + } + + function hasGlobalName(name: string): boolean { + return globals.has(escapeLeadingUnderscores(name)); + } + + function getReferencedValueSymbol(reference: Identifier, startInDeclarationContainer?: boolean): Symbol | undefined { + const resolvedSymbol = getNodeLinks(reference).resolvedSymbol; + if (resolvedSymbol) { + return resolvedSymbol; + } + + let location: Node = reference; + if (startInDeclarationContainer) { + // When resolving the name of a declaration as a value, we need to start resolution + // at a point outside of the declaration. + const parent = reference.parent; + if (isDeclaration(parent) && reference === parent.name) { + location = getDeclarationContainer(parent); + } + } + + return resolveName(location, reference.escapedText, SymbolFlags.Value | SymbolFlags.ExportValue | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + } + + /** + * Get either a value-meaning symbol or an alias symbol. + * Unlike `getReferencedValueSymbol`, if the cached resolved symbol is the unknown symbol, + * we call `resolveName` to find a symbol. + * This is because when caching the resolved symbol, we only consider value symbols, but here + * we want to also get an alias symbol if one exists. + */ + function getReferencedValueOrAliasSymbol(reference: Identifier): Symbol | undefined { + const resolvedSymbol = getNodeLinks(reference).resolvedSymbol; + if (resolvedSymbol && resolvedSymbol !== unknownSymbol) { + return resolvedSymbol; + } + + return resolveName( + reference, + reference.escapedText, + SymbolFlags.Value | SymbolFlags.ExportValue | SymbolFlags.Alias, + /*nameNotFoundMessage*/ undefined, + /*isUse*/ true, + /*excludeGlobals*/ undefined, + ); + } + + function getReferencedValueDeclaration(referenceIn: Identifier): Declaration | undefined { + if (!isGeneratedIdentifier(referenceIn)) { + const reference = getParseTreeNode(referenceIn, isIdentifier); + if (reference) { + const symbol = getReferencedValueSymbol(reference); + if (symbol) { + return getExportSymbolOfValueSymbolIfExported(symbol).valueDeclaration; + } + } + } + + return undefined; + } + + function getReferencedValueDeclarations(referenceIn: Identifier): Declaration[] | undefined { + if (!isGeneratedIdentifier(referenceIn)) { + const reference = getParseTreeNode(referenceIn, isIdentifier); + if (reference) { + const symbol = getReferencedValueSymbol(reference); + if (symbol) { + return filter(getExportSymbolOfValueSymbolIfExported(symbol).declarations, declaration => { + switch (declaration.kind) { + case SyntaxKind.VariableDeclaration: + case SyntaxKind.Parameter: + case SyntaxKind.BindingElement: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertyAssignment: + case SyntaxKind.ShorthandPropertyAssignment: + case SyntaxKind.EnumMember: + case SyntaxKind.ObjectLiteralExpression: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.ModuleDeclaration: + return true; + } + return false; + }); + } + } + } + + return undefined; + } + + function isLiteralConstDeclaration(node: VariableDeclaration | PropertyDeclaration | PropertySignature | ParameterDeclaration): boolean { + if (isDeclarationReadonly(node) || isVariableDeclaration(node) && isVarConstLike(node)) { + return isFreshLiteralType(getTypeOfSymbol(getSymbolOfDeclaration(node))); + } + return false; + } + + function literalTypeToNode(type: FreshableType, enclosing: Node, tracker: SymbolTracker): Expression { + const enumResult = type.flags & TypeFlags.EnumLike ? nodeBuilder.symbolToExpression(type.symbol, SymbolFlags.Value, enclosing, /*flags*/ undefined, tracker) + : type === trueType ? factory.createTrue() : type === falseType && factory.createFalse(); + if (enumResult) return enumResult; + const literalValue = (type as LiteralType).value; + return typeof literalValue === "object" ? factory.createBigIntLiteral(literalValue) : + typeof literalValue === "string" ? factory.createStringLiteral(literalValue) : + literalValue < 0 ? factory.createPrefixUnaryExpression(SyntaxKind.MinusToken, factory.createNumericLiteral(-literalValue)) : + factory.createNumericLiteral(literalValue); + } + + function createLiteralConstValue(node: VariableDeclaration | PropertyDeclaration | PropertySignature | ParameterDeclaration, tracker: SymbolTracker) { + const type = getTypeOfSymbol(getSymbolOfDeclaration(node)); + return literalTypeToNode(type as FreshableType, node, tracker); + } + + function getJsxFactoryEntity(location: Node): EntityName | undefined { + return location ? (getJsxNamespace(location), (getSourceFileOfNode(location).localJsxFactory || _jsxFactoryEntity)) : _jsxFactoryEntity; + } + + function getJsxFragmentFactoryEntity(location: Node): EntityName | undefined { + if (location) { + const file = getSourceFileOfNode(location); + if (file) { + if (file.localJsxFragmentFactory) { + return file.localJsxFragmentFactory; + } + const jsxFragPragmas = file.pragmas.get("jsxfrag"); + const jsxFragPragma = isArray(jsxFragPragmas) ? jsxFragPragmas[0] : jsxFragPragmas; + if (jsxFragPragma) { + file.localJsxFragmentFactory = parseIsolatedEntityName(jsxFragPragma.arguments.factory, languageVersion); + return file.localJsxFragmentFactory; + } + } + } + + if (compilerOptions.jsxFragmentFactory) { + return parseIsolatedEntityName(compilerOptions.jsxFragmentFactory, languageVersion); + } + } + + function getNonlocalEffectiveTypeAnnotationNode(node: Node) { + const direct = getEffectiveTypeAnnotationNode(node); + if (direct) { + return direct; + } + if (node.kind === SyntaxKind.Parameter && node.parent.kind === SyntaxKind.SetAccessor) { + const other = getAllAccessorDeclarationsForDeclaration(node.parent as SetAccessorDeclaration).getAccessor; + if (other) { + return getEffectiveReturnTypeNode(other); + } + } + return undefined; + } + + function getNonlocalEffectiveReturnTypeAnnotationNode(node: SignatureDeclaration | JSDocSignature) { + const direct = getEffectiveReturnTypeNode(node); + if (direct) { + return direct; + } + if (node.kind === SyntaxKind.GetAccessor) { + const other = getAllAccessorDeclarationsForDeclaration(node).setAccessor; + if (other) { + const param = getSetAccessorValueParameter(other); + if (param) { + return getEffectiveTypeAnnotationNode(param); + } + } + } + return undefined; + } + + function createResolver(): EmitResolver { + return { + getReferencedExportContainer, + getReferencedImportDeclaration, + getReferencedDeclarationWithCollidingName, + isDeclarationWithCollidingName, + isValueAliasDeclaration: nodeIn => { + const node = getParseTreeNode(nodeIn); + // Synthesized nodes are always treated like values. + return node && canCollectSymbolAliasAccessabilityData ? isValueAliasDeclaration(node) : true; + }, + hasGlobalName, + isReferencedAliasDeclaration: (nodeIn, checkChildren?) => { + const node = getParseTreeNode(nodeIn); + // Synthesized nodes are always treated as referenced. + return node && canCollectSymbolAliasAccessabilityData ? isReferencedAliasDeclaration(node, checkChildren) : true; + }, + hasNodeCheckFlag: (nodeIn, flag) => { + const node = getParseTreeNode(nodeIn); + if (!node) return false; + return hasNodeCheckFlag(node, flag); + }, + isTopLevelValueImportEqualsWithEntityName, + isDeclarationVisible, + isImplementationOfOverload, + requiresAddingImplicitUndefined, + isExpandoFunctionDeclaration, + getPropertiesOfContainerFunction, + createTypeOfDeclaration, + createReturnTypeOfSignatureDeclaration, + createTypeOfExpression, + createLiteralConstValue, + isSymbolAccessible, + isEntityNameVisible, + getConstantValue: nodeIn => { + const node = getParseTreeNode(nodeIn, canHaveConstantValue); + return node ? getConstantValue(node) : undefined; + }, + getEnumMemberValue: nodeIn => { + const node = getParseTreeNode(nodeIn, isEnumMember); + return node ? getEnumMemberValue(node) : undefined; + }, + collectLinkedAliases, + markLinkedReferences: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node && markLinkedReferences(node, ReferenceHint.Unspecified); + }, + getReferencedValueDeclaration, + getReferencedValueDeclarations, + getTypeReferenceSerializationKind, + isOptionalParameter, + isArgumentsLocalBinding, + getExternalModuleFileFromDeclaration: nodeIn => { + const node = getParseTreeNode(nodeIn, hasPossibleExternalModuleReference); + return node && getExternalModuleFileFromDeclaration(node); + }, + isLiteralConstDeclaration, + isLateBound: (nodeIn: Declaration): nodeIn is LateBoundDeclaration => { + const node = getParseTreeNode(nodeIn, isDeclaration); + const symbol = node && getSymbolOfDeclaration(node); + return !!(symbol && getCheckFlags(symbol) & CheckFlags.Late); + }, + getJsxFactoryEntity, + getJsxFragmentFactoryEntity, + isBindingCapturedByNode: (node, decl) => { + const parseNode = getParseTreeNode(node); + const parseDecl = getParseTreeNode(decl); + return !!parseNode && !!parseDecl && (isVariableDeclaration(parseDecl) || isBindingElement(parseDecl)) && isBindingCapturedByNode(parseNode, parseDecl); + }, + getDeclarationStatementsForSourceFile: (node, flags, tracker) => { + const n = getParseTreeNode(node) as SourceFile; + Debug.assert(n && n.kind === SyntaxKind.SourceFile, "Non-sourcefile node passed into getDeclarationsForSourceFile"); + const sym = getSymbolOfDeclaration(node); + if (!sym) { + return !node.locals ? [] : nodeBuilder.symbolTableToDeclarationStatements(node.locals, node, flags, tracker); + } + resolveExternalModuleSymbol(sym); // ensures cjs export assignment is setup + return !sym.exports ? [] : nodeBuilder.symbolTableToDeclarationStatements(sym.exports, node, flags, tracker); + }, + isImportRequiredByAugmentation, + isDefinitelyReferenceToGlobalSymbolObject, + }; + + function isImportRequiredByAugmentation(node: ImportDeclaration) { + const file = getSourceFileOfNode(node); + if (!file.symbol) return false; + const importTarget = getExternalModuleFileFromDeclaration(node); + if (!importTarget) return false; + if (importTarget === file) return false; + const exports = getExportsOfModule(file.symbol); + for (const s of arrayFrom(exports.values())) { + if (s.mergeId) { + const merged = getMergedSymbol(s); + if (merged.declarations) { + for (const d of merged.declarations) { + const declFile = getSourceFileOfNode(d); + if (declFile === importTarget) { + return true; + } + } + } + } + } + return false; + } + } + + function getExternalModuleFileFromDeclaration(declaration: AnyImportOrReExport | ModuleDeclaration | ImportTypeNode | ImportCall): SourceFile | undefined { + const specifier = declaration.kind === SyntaxKind.ModuleDeclaration ? tryCast(declaration.name, isStringLiteral) : getExternalModuleName(declaration); + const moduleSymbol = resolveExternalModuleNameWorker(specifier!, specifier!, /*moduleNotFoundError*/ undefined); // TODO: GH#18217 + if (!moduleSymbol) { + return undefined; + } + return getDeclarationOfKind(moduleSymbol, SyntaxKind.SourceFile); + } + + function initializeTypeChecker() { + // Bind all source files and propagate errors + for (const file of host.getSourceFiles()) { + bindSourceFile(file, compilerOptions); + } + + amalgamatedDuplicates = new Map(); + + // Initialize global symbol table + let augmentations: (readonly (StringLiteral | Identifier)[])[] | undefined; + for (const file of host.getSourceFiles()) { + if (file.redirectInfo) { + continue; + } + if (!isExternalOrCommonJsModule(file)) { + // It is an error for a non-external-module (i.e. script) to declare its own `globalThis`. + const fileGlobalThisSymbol = file.locals!.get("globalThis" as __String); + if (fileGlobalThisSymbol?.declarations) { + for (const declaration of fileGlobalThisSymbol.declarations) { + diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Declaration_name_conflicts_with_built_in_global_identifier_0, "globalThis")); + } + } + mergeSymbolTable(globals, file.locals!); + } + if (file.jsGlobalAugmentations) { + mergeSymbolTable(globals, file.jsGlobalAugmentations); + } + if (file.patternAmbientModules && file.patternAmbientModules.length) { + patternAmbientModules = concatenate(patternAmbientModules, file.patternAmbientModules); + } + if (file.moduleAugmentations.length) { + (augmentations || (augmentations = [])).push(file.moduleAugmentations); + } + if (file.symbol && file.symbol.globalExports) { + // Merge in UMD exports with first-in-wins semantics (see #9771) + const source = file.symbol.globalExports; + source.forEach((sourceSymbol, id) => { + if (!globals.has(id)) { + globals.set(id, sourceSymbol); + } + }); + } + } + + // We do global augmentations separately from module augmentations (and before creating global types) because they + // 1. Affect global types. We won't have the correct global types until global augmentations are merged. Also, + // 2. Module augmentation instantiation requires creating the type of a module, which, in turn, can require + // checking for an export or property on the module (if export=) which, in turn, can fall back to the + // apparent type of the module - either globalObjectType or globalFunctionType - which wouldn't exist if we + // did module augmentations prior to finalizing the global types. + if (augmentations) { + // merge _global_ module augmentations. + // this needs to be done after global symbol table is initialized to make sure that all ambient modules are indexed + for (const list of augmentations) { + for (const augmentation of list) { + if (!isGlobalScopeAugmentation(augmentation.parent as ModuleDeclaration)) continue; + mergeModuleAugmentation(augmentation); + } + } + } + + addUndefinedToGlobalsOrErrorOnRedeclaration(); + + getSymbolLinks(undefinedSymbol).type = undefinedWideningType; + getSymbolLinks(argumentsSymbol).type = getGlobalType("IArguments" as __String, /*arity*/ 0, /*reportErrors*/ true); + getSymbolLinks(unknownSymbol).type = errorType; + getSymbolLinks(globalThisSymbol).type = createObjectType(ObjectFlags.Anonymous, globalThisSymbol); + + // Initialize special types + globalArrayType = getGlobalType("Array" as __String, /*arity*/ 1, /*reportErrors*/ true); + globalObjectType = getGlobalType("Object" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalFunctionType = getGlobalType("Function" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalCallableFunctionType = strictBindCallApply && getGlobalType("CallableFunction" as __String, /*arity*/ 0, /*reportErrors*/ true) || globalFunctionType; + globalNewableFunctionType = strictBindCallApply && getGlobalType("NewableFunction" as __String, /*arity*/ 0, /*reportErrors*/ true) || globalFunctionType; + globalStringType = getGlobalType("String" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalNumberType = getGlobalType("Number" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalBooleanType = getGlobalType("Boolean" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalRegExpType = getGlobalType("RegExp" as __String, /*arity*/ 0, /*reportErrors*/ true); + anyArrayType = createArrayType(anyType); + + autoArrayType = createArrayType(autoType); + if (autoArrayType === emptyObjectType) { + // autoArrayType is used as a marker, so even if global Array type is not defined, it needs to be a unique type + autoArrayType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + } + + globalReadonlyArrayType = getGlobalTypeOrUndefined("ReadonlyArray" as __String, /*arity*/ 1) as GenericType || globalArrayType; + anyReadonlyArrayType = globalReadonlyArrayType ? createTypeFromGenericGlobalType(globalReadonlyArrayType, [anyType]) : anyArrayType; + globalThisType = getGlobalTypeOrUndefined("ThisType" as __String, /*arity*/ 1) as GenericType; + + if (augmentations) { + // merge _nonglobal_ module augmentations. + // this needs to be done after global symbol table is initialized to make sure that all ambient modules are indexed + for (const list of augmentations) { + for (const augmentation of list) { + if (isGlobalScopeAugmentation(augmentation.parent as ModuleDeclaration)) continue; + mergeModuleAugmentation(augmentation); + } + } + } + + amalgamatedDuplicates.forEach(({ firstFile, secondFile, conflictingSymbols }) => { + // If not many things conflict, issue individual errors + if (conflictingSymbols.size < 8) { + conflictingSymbols.forEach(({ isBlockScoped, firstFileLocations, secondFileLocations }, symbolName) => { + const message = isBlockScoped ? Diagnostics.Cannot_redeclare_block_scoped_variable_0 : Diagnostics.Duplicate_identifier_0; + for (const node of firstFileLocations) { + addDuplicateDeclarationError(node, message, symbolName, secondFileLocations); + } + for (const node of secondFileLocations) { + addDuplicateDeclarationError(node, message, symbolName, firstFileLocations); + } + }); + } + else { + // Otherwise issue top-level error since the files appear very identical in terms of what they contain + const list = arrayFrom(conflictingSymbols.keys()).join(", "); + diagnostics.add(addRelatedInfo( + createDiagnosticForNode(firstFile, Diagnostics.Definitions_of_the_following_identifiers_conflict_with_those_in_another_file_Colon_0, list), + createDiagnosticForNode(secondFile, Diagnostics.Conflicts_are_in_this_file), + )); + diagnostics.add(addRelatedInfo( + createDiagnosticForNode(secondFile, Diagnostics.Definitions_of_the_following_identifiers_conflict_with_those_in_another_file_Colon_0, list), + createDiagnosticForNode(firstFile, Diagnostics.Conflicts_are_in_this_file), + )); + } + }); + amalgamatedDuplicates = undefined; + } + + function checkExternalEmitHelpers(location: Node, helpers: ExternalEmitHelpers) { + if (compilerOptions.importHelpers) { + const sourceFile = getSourceFileOfNode(location); + if (isEffectiveExternalModule(sourceFile, compilerOptions) && !(location.flags & NodeFlags.Ambient)) { + const helpersModule = resolveHelpersModule(sourceFile, location); + if (helpersModule !== unknownSymbol) { + const links = getSymbolLinks(helpersModule); + links.requestedExternalEmitHelpers ??= 0 as ExternalEmitHelpers; + if ((links.requestedExternalEmitHelpers & helpers) !== helpers) { + const uncheckedHelpers = helpers & ~links.requestedExternalEmitHelpers; + for (let helper = ExternalEmitHelpers.FirstEmitHelper; helper <= ExternalEmitHelpers.LastEmitHelper; helper <<= 1) { + if (uncheckedHelpers & helper) { + for (const name of getHelperNames(helper)) { + const symbol = resolveSymbol(getSymbol(getExportsOfModule(helpersModule), escapeLeadingUnderscores(name), SymbolFlags.Value)); + if (!symbol) { + error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_which_does_not_exist_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name); + } + else if (helper & ExternalEmitHelpers.ClassPrivateFieldGet) { + if (!some(getSignaturesOfSymbol(symbol), signature => getParameterCount(signature) > 3)) { + error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_with_2_parameters_which_is_not_compatible_with_the_one_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name, 4); + } + } + else if (helper & ExternalEmitHelpers.ClassPrivateFieldSet) { + if (!some(getSignaturesOfSymbol(symbol), signature => getParameterCount(signature) > 4)) { + error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_with_2_parameters_which_is_not_compatible_with_the_one_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name, 5); + } + } + else if (helper & ExternalEmitHelpers.SpreadArray) { + if (!some(getSignaturesOfSymbol(symbol), signature => getParameterCount(signature) > 2)) { + error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_with_2_parameters_which_is_not_compatible_with_the_one_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name, 3); + } + } + } + } + } + } + links.requestedExternalEmitHelpers |= helpers; + } + } + } + } + + function getHelperNames(helper: ExternalEmitHelpers) { + switch (helper) { + case ExternalEmitHelpers.Extends: + return ["__extends"]; + case ExternalEmitHelpers.Assign: + return ["__assign"]; + case ExternalEmitHelpers.Rest: + return ["__rest"]; + case ExternalEmitHelpers.Decorate: + return legacyDecorators ? ["__decorate"] : ["__esDecorate", "__runInitializers"]; + case ExternalEmitHelpers.Metadata: + return ["__metadata"]; + case ExternalEmitHelpers.Param: + return ["__param"]; + case ExternalEmitHelpers.Awaiter: + return ["__awaiter"]; + case ExternalEmitHelpers.Generator: + return ["__generator"]; + case ExternalEmitHelpers.Values: + return ["__values"]; + case ExternalEmitHelpers.Read: + return ["__read"]; + case ExternalEmitHelpers.SpreadArray: + return ["__spreadArray"]; + case ExternalEmitHelpers.Await: + return ["__await"]; + case ExternalEmitHelpers.AsyncGenerator: + return ["__asyncGenerator"]; + case ExternalEmitHelpers.AsyncDelegator: + return ["__asyncDelegator"]; + case ExternalEmitHelpers.AsyncValues: + return ["__asyncValues"]; + case ExternalEmitHelpers.ExportStar: + return ["__exportStar"]; + case ExternalEmitHelpers.ImportStar: + return ["__importStar"]; + case ExternalEmitHelpers.ImportDefault: + return ["__importDefault"]; + case ExternalEmitHelpers.MakeTemplateObject: + return ["__makeTemplateObject"]; + case ExternalEmitHelpers.ClassPrivateFieldGet: + return ["__classPrivateFieldGet"]; + case ExternalEmitHelpers.ClassPrivateFieldSet: + return ["__classPrivateFieldSet"]; + case ExternalEmitHelpers.ClassPrivateFieldIn: + return ["__classPrivateFieldIn"]; + case ExternalEmitHelpers.SetFunctionName: + return ["__setFunctionName"]; + case ExternalEmitHelpers.PropKey: + return ["__propKey"]; + case ExternalEmitHelpers.AddDisposableResourceAndDisposeResources: + return ["__addDisposableResource", "__disposeResources"]; + default: + return Debug.fail("Unrecognized helper"); + } + } + + function resolveHelpersModule(file: SourceFile, errorNode: Node) { + const links = getNodeLinks(file); + if (!links.externalHelpersModule) { + links.externalHelpersModule = resolveExternalModule(getImportHelpersImportSpecifier(file), externalHelpersModuleNameText, Diagnostics.This_syntax_requires_an_imported_helper_but_module_0_cannot_be_found, errorNode) || unknownSymbol; + } + return links.externalHelpersModule; + } + + // GRAMMAR CHECKING + + function checkGrammarModifiers(node: HasModifiers | HasDecorators | HasIllegalModifiers | HasIllegalDecorators): boolean { + const quickResult = reportObviousDecoratorErrors(node) || reportObviousModifierErrors(node); + if (quickResult !== undefined) { + return quickResult; + } + + if (isParameter(node) && parameterIsThisKeyword(node)) { + return grammarErrorOnFirstToken(node, Diagnostics.Neither_decorators_nor_modifiers_may_be_applied_to_this_parameters); + } + + const blockScopeKind = isVariableStatement(node) ? node.declarationList.flags & NodeFlags.BlockScoped : NodeFlags.None; + let lastStatic: Node | undefined, lastDeclare: Node | undefined, lastAsync: Node | undefined, lastOverride: Node | undefined, firstDecorator: Decorator | undefined; + let flags = ModifierFlags.None; + let sawExportBeforeDecorators = false; + // We parse decorators and modifiers in four contiguous chunks: + // [...leadingDecorators, ...leadingModifiers, ...trailingDecorators, ...trailingModifiers]. It is an error to + // have both leading and trailing decorators. + let hasLeadingDecorators = false; + for (const modifier of (node as HasModifiers).modifiers!) { + if (isDecorator(modifier)) { + if (!nodeCanBeDecorated(legacyDecorators, node, node.parent, node.parent.parent)) { + if (node.kind === SyntaxKind.MethodDeclaration && !nodeIsPresent(node.body)) { + return grammarErrorOnFirstToken(node, Diagnostics.A_decorator_can_only_decorate_a_method_implementation_not_an_overload); + } + else { + return grammarErrorOnFirstToken(node, Diagnostics.Decorators_are_not_valid_here); + } + } + else if (legacyDecorators && (node.kind === SyntaxKind.GetAccessor || node.kind === SyntaxKind.SetAccessor)) { + const accessors = getAllAccessorDeclarationsForDeclaration(node as AccessorDeclaration); + if (hasDecorators(accessors.firstAccessor) && node === accessors.secondAccessor) { + return grammarErrorOnFirstToken(node, Diagnostics.Decorators_cannot_be_applied_to_multiple_get_Slashset_accessors_of_the_same_name); + } + } + + // if we've seen any modifiers aside from `export`, `default`, or another decorator, then this is an invalid position + if (flags & ~(ModifierFlags.ExportDefault | ModifierFlags.Decorator)) { + return grammarErrorOnNode(modifier, Diagnostics.Decorators_are_not_valid_here); + } + + // if we've already seen leading decorators and leading modifiers, then trailing decorators are an invalid position + if (hasLeadingDecorators && flags & ModifierFlags.Modifier) { + Debug.assertIsDefined(firstDecorator); + const sourceFile = getSourceFileOfNode(modifier); + if (!hasParseDiagnostics(sourceFile)) { + addRelatedInfo( + error(modifier, Diagnostics.Decorators_may_not_appear_after_export_or_export_default_if_they_also_appear_before_export), + createDiagnosticForNode(firstDecorator, Diagnostics.Decorator_used_before_export_here), + ); + return true; + } + return false; + } + + flags |= ModifierFlags.Decorator; + + // if we have not yet seen a modifier, then these are leading decorators + if (!(flags & ModifierFlags.Modifier)) { + hasLeadingDecorators = true; + } + else if (flags & ModifierFlags.Export) { + sawExportBeforeDecorators = true; + } + + firstDecorator ??= modifier; + } + else { + if (modifier.kind !== SyntaxKind.ReadonlyKeyword) { + if (node.kind === SyntaxKind.PropertySignature || node.kind === SyntaxKind.MethodSignature) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_type_member, tokenToString(modifier.kind)); + } + if (node.kind === SyntaxKind.IndexSignature && (modifier.kind !== SyntaxKind.StaticKeyword || !isClassLike(node.parent))) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_an_index_signature, tokenToString(modifier.kind)); + } + } + if (modifier.kind !== SyntaxKind.InKeyword && modifier.kind !== SyntaxKind.OutKeyword && modifier.kind !== SyntaxKind.ConstKeyword) { + if (node.kind === SyntaxKind.TypeParameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_type_parameter, tokenToString(modifier.kind)); + } + } + switch (modifier.kind) { + case SyntaxKind.ConstKeyword: { + if (node.kind !== SyntaxKind.EnumDeclaration && node.kind !== SyntaxKind.TypeParameter) { + return grammarErrorOnNode(node, Diagnostics.A_class_member_cannot_have_the_0_keyword, tokenToString(SyntaxKind.ConstKeyword)); + } + const parent = (isJSDocTemplateTag(node.parent) && getEffectiveJSDocHost(node.parent)) || node.parent; + if ( + node.kind === SyntaxKind.TypeParameter && !(isFunctionLikeDeclaration(parent) || isClassLike(parent) || isFunctionTypeNode(parent) || + isConstructorTypeNode(parent) || isCallSignatureDeclaration(parent) || isConstructSignatureDeclaration(parent) || isMethodSignature(parent)) + ) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_can_only_appear_on_a_type_parameter_of_a_function_method_or_class, tokenToString(modifier.kind)); + } + break; + } + case SyntaxKind.OverrideKeyword: + // If node.kind === SyntaxKind.Parameter, checkParameter reports an error if it's not a parameter property. + if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "override"); + } + else if (flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "override", "declare"); + } + else if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "override", "readonly"); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "override", "accessor"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "override", "async"); + } + flags |= ModifierFlags.Override; + lastOverride = modifier; + break; + + case SyntaxKind.PublicKeyword: + case SyntaxKind.ProtectedKeyword: + case SyntaxKind.PrivateKeyword: + const text = visibilityToString(modifierToFlag(modifier.kind)); + + if (flags & ModifierFlags.AccessibilityModifier) { + return grammarErrorOnNode(modifier, Diagnostics.Accessibility_modifier_already_seen); + } + else if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "override"); + } + else if (flags & ModifierFlags.Static) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "static"); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "accessor"); + } + else if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "readonly"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "async"); + } + else if (node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_module_or_namespace_element, text); + } + else if (flags & ModifierFlags.Abstract) { + if (modifier.kind === SyntaxKind.PrivateKeyword) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, text, "abstract"); + } + else { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "abstract"); + } + } + else if (isPrivateIdentifierClassElementDeclaration(node)) { + return grammarErrorOnNode(modifier, Diagnostics.An_accessibility_modifier_cannot_be_used_with_a_private_identifier); + } + flags |= modifierToFlag(modifier.kind); + break; + + case SyntaxKind.StaticKeyword: + if (flags & ModifierFlags.Static) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "static"); + } + else if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "readonly"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "async"); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "accessor"); + } + else if (node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_module_or_namespace_element, "static"); + } + else if (node.kind === SyntaxKind.Parameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "static"); + } + else if (flags & ModifierFlags.Abstract) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "static", "abstract"); + } + else if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "override"); + } + flags |= ModifierFlags.Static; + lastStatic = modifier; + break; + + case SyntaxKind.AccessorKeyword: + if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "accessor"); + } + else if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "accessor", "readonly"); + } + else if (flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "accessor", "declare"); + } + else if (node.kind !== SyntaxKind.PropertyDeclaration) { + return grammarErrorOnNode(modifier, Diagnostics.accessor_modifier_can_only_appear_on_a_property_declaration); + } + + flags |= ModifierFlags.Accessor; + break; + + case SyntaxKind.ReadonlyKeyword: + if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "readonly"); + } + else if (node.kind !== SyntaxKind.PropertyDeclaration && node.kind !== SyntaxKind.PropertySignature && node.kind !== SyntaxKind.IndexSignature && node.kind !== SyntaxKind.Parameter) { + // If node.kind === SyntaxKind.Parameter, checkParameter reports an error if it's not a parameter property. + return grammarErrorOnNode(modifier, Diagnostics.readonly_modifier_can_only_appear_on_a_property_declaration_or_index_signature); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "readonly", "accessor"); + } + flags |= ModifierFlags.Readonly; + break; + + case SyntaxKind.ExportKeyword: + if ( + compilerOptions.verbatimModuleSyntax && + !(node.flags & NodeFlags.Ambient) && + node.kind !== SyntaxKind.TypeAliasDeclaration && + node.kind !== SyntaxKind.InterfaceDeclaration && + // ModuleDeclaration needs to be checked that it is uninstantiated later + node.kind !== SyntaxKind.ModuleDeclaration && + node.parent.kind === SyntaxKind.SourceFile && + (moduleKind === ModuleKind.CommonJS || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) + ) { + return grammarErrorOnNode(modifier, Diagnostics.A_top_level_export_modifier_cannot_be_used_on_value_declarations_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + if (flags & ModifierFlags.Export) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "export"); + } + else if (flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "declare"); + } + else if (flags & ModifierFlags.Abstract) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "abstract"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "async"); + } + else if (isClassLike(node.parent)) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_class_elements_of_this_kind, "export"); + } + else if (node.kind === SyntaxKind.Parameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "export"); + } + else if (blockScopeKind === NodeFlags.Using) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_using_declaration, "export"); + } + else if (blockScopeKind === NodeFlags.AwaitUsing) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_an_await_using_declaration, "export"); + } + flags |= ModifierFlags.Export; + break; + case SyntaxKind.DefaultKeyword: + const container = node.parent.kind === SyntaxKind.SourceFile ? node.parent : node.parent.parent; + if (container.kind === SyntaxKind.ModuleDeclaration && !isAmbientModule(container)) { + return grammarErrorOnNode(modifier, Diagnostics.A_default_export_can_only_be_used_in_an_ECMAScript_style_module); + } + else if (blockScopeKind === NodeFlags.Using) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_using_declaration, "default"); + } + else if (blockScopeKind === NodeFlags.AwaitUsing) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_an_await_using_declaration, "default"); + } + else if (!(flags & ModifierFlags.Export)) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "default"); + } + else if (sawExportBeforeDecorators) { + return grammarErrorOnNode(firstDecorator!, Diagnostics.Decorators_are_not_valid_here); + } + + flags |= ModifierFlags.Default; + break; + case SyntaxKind.DeclareKeyword: + if (flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "declare"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_in_an_ambient_context, "async"); + } + else if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_in_an_ambient_context, "override"); + } + else if (isClassLike(node.parent) && !isPropertyDeclaration(node)) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_class_elements_of_this_kind, "declare"); + } + else if (node.kind === SyntaxKind.Parameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "declare"); + } + else if (blockScopeKind === NodeFlags.Using) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_using_declaration, "declare"); + } + else if (blockScopeKind === NodeFlags.AwaitUsing) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_an_await_using_declaration, "declare"); + } + else if ((node.parent.flags & NodeFlags.Ambient) && node.parent.kind === SyntaxKind.ModuleBlock) { + return grammarErrorOnNode(modifier, Diagnostics.A_declare_modifier_cannot_be_used_in_an_already_ambient_context); + } + else if (isPrivateIdentifierClassElementDeclaration(node)) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_a_private_identifier, "declare"); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "declare", "accessor"); + } + flags |= ModifierFlags.Ambient; + lastDeclare = modifier; + break; + + case SyntaxKind.AbstractKeyword: + if (flags & ModifierFlags.Abstract) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "abstract"); + } + if ( + node.kind !== SyntaxKind.ClassDeclaration && + node.kind !== SyntaxKind.ConstructorType + ) { + if ( + node.kind !== SyntaxKind.MethodDeclaration && + node.kind !== SyntaxKind.PropertyDeclaration && + node.kind !== SyntaxKind.GetAccessor && + node.kind !== SyntaxKind.SetAccessor + ) { + return grammarErrorOnNode(modifier, Diagnostics.abstract_modifier_can_only_appear_on_a_class_method_or_property_declaration); + } + if (!(node.parent.kind === SyntaxKind.ClassDeclaration && hasSyntacticModifier(node.parent, ModifierFlags.Abstract))) { + const message = node.kind === SyntaxKind.PropertyDeclaration + ? Diagnostics.Abstract_properties_can_only_appear_within_an_abstract_class + : Diagnostics.Abstract_methods_can_only_appear_within_an_abstract_class; + return grammarErrorOnNode(modifier, message); + } + if (flags & ModifierFlags.Static) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "static", "abstract"); + } + if (flags & ModifierFlags.Private) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "private", "abstract"); + } + if (flags & ModifierFlags.Async && lastAsync) { + return grammarErrorOnNode(lastAsync, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "async", "abstract"); + } + if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "abstract", "override"); + } + if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "abstract", "accessor"); + } + } + if (isNamedDeclaration(node) && node.name.kind === SyntaxKind.PrivateIdentifier) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_a_private_identifier, "abstract"); + } + + flags |= ModifierFlags.Abstract; + break; + + case SyntaxKind.AsyncKeyword: + if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "async"); + } + else if (flags & ModifierFlags.Ambient || node.parent.flags & NodeFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_in_an_ambient_context, "async"); + } + else if (node.kind === SyntaxKind.Parameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "async"); + } + if (flags & ModifierFlags.Abstract) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "async", "abstract"); + } + flags |= ModifierFlags.Async; + lastAsync = modifier; + break; + + case SyntaxKind.InKeyword: + case SyntaxKind.OutKeyword: { + const inOutFlag = modifier.kind === SyntaxKind.InKeyword ? ModifierFlags.In : ModifierFlags.Out; + const inOutText = modifier.kind === SyntaxKind.InKeyword ? "in" : "out"; + const parent = isJSDocTemplateTag(node.parent) && (getEffectiveJSDocHost(node.parent) || find(getJSDocRoot(node.parent)?.tags, isJSDocTypedefTag)) || node.parent; + if (node.kind !== SyntaxKind.TypeParameter || parent && !(isInterfaceDeclaration(parent) || isClassLike(parent) || isTypeAliasDeclaration(parent) || isJSDocTypedefTag(parent))) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_can_only_appear_on_a_type_parameter_of_a_class_interface_or_type_alias, inOutText); + } + if (flags & inOutFlag) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, inOutText); + } + if (inOutFlag & ModifierFlags.In && flags & ModifierFlags.Out) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "in", "out"); + } + flags |= inOutFlag; + break; + } + } + } + } + + if (node.kind === SyntaxKind.Constructor) { + if (flags & ModifierFlags.Static) { + return grammarErrorOnNode(lastStatic!, Diagnostics._0_modifier_cannot_appear_on_a_constructor_declaration, "static"); + } + if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(lastOverride!, Diagnostics._0_modifier_cannot_appear_on_a_constructor_declaration, "override"); // TODO: GH#18217 + } + if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(lastAsync!, Diagnostics._0_modifier_cannot_appear_on_a_constructor_declaration, "async"); + } + return false; + } + else if ((node.kind === SyntaxKind.ImportDeclaration || node.kind === SyntaxKind.ImportEqualsDeclaration) && flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(lastDeclare!, Diagnostics.A_0_modifier_cannot_be_used_with_an_import_declaration, "declare"); + } + else if (node.kind === SyntaxKind.Parameter && (flags & ModifierFlags.ParameterPropertyModifier) && isBindingPattern(node.name)) { + return grammarErrorOnNode(node, Diagnostics.A_parameter_property_may_not_be_declared_using_a_binding_pattern); + } + else if (node.kind === SyntaxKind.Parameter && (flags & ModifierFlags.ParameterPropertyModifier) && node.dotDotDotToken) { + return grammarErrorOnNode(node, Diagnostics.A_parameter_property_cannot_be_declared_using_a_rest_parameter); + } + if (flags & ModifierFlags.Async) { + return checkGrammarAsyncModifier(node, lastAsync!); + } + return false; + } + + /** + * true | false: Early return this value from checkGrammarModifiers. + * undefined: Need to do full checking on the modifiers. + */ + function reportObviousModifierErrors(node: HasModifiers | HasIllegalModifiers): boolean | undefined { + if (!node.modifiers) return false; + + const modifier = findFirstIllegalModifier(node); + return modifier && grammarErrorOnFirstToken(modifier, Diagnostics.Modifiers_cannot_appear_here); + } + + function findFirstModifierExcept(node: HasModifiers, allowedModifier: SyntaxKind): Modifier | undefined { + const modifier = find(node.modifiers, isModifier); + return modifier && modifier.kind !== allowedModifier ? modifier : undefined; + } + + function findFirstIllegalModifier(node: HasModifiers | HasIllegalModifiers): Modifier | undefined { + switch (node.kind) { + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.Constructor: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + case SyntaxKind.IndexSignature: + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.ImportDeclaration: + case SyntaxKind.ImportEqualsDeclaration: + case SyntaxKind.ExportDeclaration: + case SyntaxKind.ExportAssignment: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.Parameter: + case SyntaxKind.TypeParameter: + return undefined; + case SyntaxKind.ClassStaticBlockDeclaration: + case SyntaxKind.PropertyAssignment: + case SyntaxKind.ShorthandPropertyAssignment: + case SyntaxKind.NamespaceExportDeclaration: + case SyntaxKind.MissingDeclaration: + return find(node.modifiers, isModifier); + default: + if (node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { + return undefined; + } + switch (node.kind) { + case SyntaxKind.FunctionDeclaration: + return findFirstModifierExcept(node, SyntaxKind.AsyncKeyword); + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ConstructorType: + return findFirstModifierExcept(node, SyntaxKind.AbstractKeyword); + case SyntaxKind.ClassExpression: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + return find(node.modifiers, isModifier); + case SyntaxKind.VariableStatement: + return node.declarationList.flags & NodeFlags.Using ? + findFirstModifierExcept(node, SyntaxKind.AwaitKeyword) : + find(node.modifiers, isModifier); + case SyntaxKind.EnumDeclaration: + return findFirstModifierExcept(node, SyntaxKind.ConstKeyword); + default: + Debug.assertNever(node); + } + } + } + + function reportObviousDecoratorErrors(node: HasModifiers | HasDecorators | HasIllegalModifiers | HasIllegalDecorators) { + const decorator = findFirstIllegalDecorator(node); + return decorator && grammarErrorOnFirstToken(decorator, Diagnostics.Decorators_are_not_valid_here); + } + + function findFirstIllegalDecorator(node: HasModifiers | HasDecorators | HasIllegalModifiers | HasIllegalDecorators): Decorator | undefined { + return canHaveIllegalDecorators(node) ? find(node.modifiers, isDecorator) : undefined; + } + + function checkGrammarAsyncModifier(node: Node, asyncModifier: Node): boolean { + switch (node.kind) { + case SyntaxKind.MethodDeclaration: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + return false; + } + + return grammarErrorOnNode(asyncModifier, Diagnostics._0_modifier_cannot_be_used_here, "async"); + } + + function checkGrammarForDisallowedTrailingComma(list: NodeArray | undefined, diag = Diagnostics.Trailing_comma_not_allowed): boolean { + if (list && list.hasTrailingComma) { + return grammarErrorAtPos(list[0], list.end - ",".length, ",".length, diag); + } + return false; + } + + function checkGrammarTypeParameterList(typeParameters: NodeArray | undefined, file: SourceFile): boolean { + if (typeParameters && typeParameters.length === 0) { + const start = typeParameters.pos - "<".length; + const end = skipTrivia(file.text, typeParameters.end) + ">".length; + return grammarErrorAtPos(file, start, end - start, Diagnostics.Type_parameter_list_cannot_be_empty); + } + return false; + } + + function checkGrammarParameterList(parameters: NodeArray) { + let seenOptionalParameter = false; + const parameterCount = parameters.length; + + for (let i = 0; i < parameterCount; i++) { + const parameter = parameters[i]; + if (parameter.dotDotDotToken) { + if (i !== (parameterCount - 1)) { + return grammarErrorOnNode(parameter.dotDotDotToken, Diagnostics.A_rest_parameter_must_be_last_in_a_parameter_list); + } + if (!(parameter.flags & NodeFlags.Ambient)) { // Allow `...foo,` in ambient declarations; see GH#23070 + checkGrammarForDisallowedTrailingComma(parameters, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + } + + if (parameter.questionToken) { + return grammarErrorOnNode(parameter.questionToken, Diagnostics.A_rest_parameter_cannot_be_optional); + } + + if (parameter.initializer) { + return grammarErrorOnNode(parameter.name, Diagnostics.A_rest_parameter_cannot_have_an_initializer); + } + } + else if (hasEffectiveQuestionToken(parameter)) { + seenOptionalParameter = true; + if (parameter.questionToken && parameter.initializer) { + return grammarErrorOnNode(parameter.name, Diagnostics.Parameter_cannot_have_question_mark_and_initializer); + } + } + else if (seenOptionalParameter && !parameter.initializer) { + return grammarErrorOnNode(parameter.name, Diagnostics.A_required_parameter_cannot_follow_an_optional_parameter); + } + } + } + + function getNonSimpleParameters(parameters: readonly ParameterDeclaration[]): readonly ParameterDeclaration[] { + return filter(parameters, parameter => !!parameter.initializer || isBindingPattern(parameter.name) || isRestParameter(parameter)); + } + + function checkGrammarForUseStrictSimpleParameterList(node: FunctionLikeDeclaration): boolean { + if (languageVersion >= ScriptTarget.ES2016) { + const useStrictDirective = node.body && isBlock(node.body) && findUseStrictPrologue(node.body.statements); + if (useStrictDirective) { + const nonSimpleParameters = getNonSimpleParameters(node.parameters); + if (length(nonSimpleParameters)) { + forEach(nonSimpleParameters, parameter => { + addRelatedInfo( + error(parameter, Diagnostics.This_parameter_is_not_allowed_with_use_strict_directive), + createDiagnosticForNode(useStrictDirective, Diagnostics.use_strict_directive_used_here), + ); + }); + + const diagnostics = nonSimpleParameters.map((parameter, index) => ( + index === 0 ? createDiagnosticForNode(parameter, Diagnostics.Non_simple_parameter_declared_here) : createDiagnosticForNode(parameter, Diagnostics.and_here) + )) as [DiagnosticWithLocation, ...DiagnosticWithLocation[]]; + addRelatedInfo(error(useStrictDirective, Diagnostics.use_strict_directive_cannot_be_used_with_non_simple_parameter_list), ...diagnostics); + return true; + } + } + } + return false; + } + + function checkGrammarFunctionLikeDeclaration(node: FunctionLikeDeclaration | MethodSignature): boolean { + // Prevent cascading error by short-circuit + const file = getSourceFileOfNode(node); + return checkGrammarModifiers(node) || + checkGrammarTypeParameterList(node.typeParameters, file) || + checkGrammarParameterList(node.parameters) || + checkGrammarArrowFunction(node, file) || + (isFunctionLikeDeclaration(node) && checkGrammarForUseStrictSimpleParameterList(node)); + } + + function checkGrammarClassLikeDeclaration(node: ClassLikeDeclaration): boolean { + const file = getSourceFileOfNode(node); + return checkGrammarClassDeclarationHeritageClauses(node) || + checkGrammarTypeParameterList(node.typeParameters, file); + } + + function checkGrammarArrowFunction(node: Node, file: SourceFile): boolean { + if (!isArrowFunction(node)) { + return false; + } + + if (node.typeParameters && !(length(node.typeParameters) > 1 || node.typeParameters.hasTrailingComma || node.typeParameters[0].constraint)) { + if (file && fileExtensionIsOneOf(file.fileName, [Extension.Mts, Extension.Cts])) { + grammarErrorOnNode(node.typeParameters[0], Diagnostics.This_syntax_is_reserved_in_files_with_the_mts_or_cts_extension_Add_a_trailing_comma_or_explicit_constraint); + } + } + + const { equalsGreaterThanToken } = node; + const startLine = getLineAndCharacterOfPosition(file, equalsGreaterThanToken.pos).line; + const endLine = getLineAndCharacterOfPosition(file, equalsGreaterThanToken.end).line; + return startLine !== endLine && grammarErrorOnNode(equalsGreaterThanToken, Diagnostics.Line_terminator_not_permitted_before_arrow); + } + + function checkGrammarIndexSignatureParameters(node: SignatureDeclaration): boolean { + const parameter = node.parameters[0]; + if (node.parameters.length !== 1) { + if (parameter) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_must_have_exactly_one_parameter); + } + else { + return grammarErrorOnNode(node, Diagnostics.An_index_signature_must_have_exactly_one_parameter); + } + } + checkGrammarForDisallowedTrailingComma(node.parameters, Diagnostics.An_index_signature_cannot_have_a_trailing_comma); + if (parameter.dotDotDotToken) { + return grammarErrorOnNode(parameter.dotDotDotToken, Diagnostics.An_index_signature_cannot_have_a_rest_parameter); + } + if (hasEffectiveModifiers(parameter)) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_cannot_have_an_accessibility_modifier); + } + if (parameter.questionToken) { + return grammarErrorOnNode(parameter.questionToken, Diagnostics.An_index_signature_parameter_cannot_have_a_question_mark); + } + if (parameter.initializer) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_cannot_have_an_initializer); + } + if (!parameter.type) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_must_have_a_type_annotation); + } + const type = getTypeFromTypeNode(parameter.type); + if (someType(type, t => !!(t.flags & TypeFlags.StringOrNumberLiteralOrUnique)) || isGenericType(type)) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_type_cannot_be_a_literal_type_or_generic_type_Consider_using_a_mapped_object_type_instead); + } + if (!everyType(type, isValidIndexKeyType)) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_type_must_be_string_number_symbol_or_a_template_literal_type); + } + if (!node.type) { + return grammarErrorOnNode(node, Diagnostics.An_index_signature_must_have_a_type_annotation); + } + return false; + } + + function checkGrammarIndexSignature(node: IndexSignatureDeclaration) { + // Prevent cascading error by short-circuit + return checkGrammarModifiers(node) || checkGrammarIndexSignatureParameters(node); + } + + function checkGrammarForAtLeastOneTypeArgument(node: Node, typeArguments: NodeArray | undefined): boolean { + if (typeArguments && typeArguments.length === 0) { + const sourceFile = getSourceFileOfNode(node); + const start = typeArguments.pos - "<".length; + const end = skipTrivia(sourceFile.text, typeArguments.end) + ">".length; + return grammarErrorAtPos(sourceFile, start, end - start, Diagnostics.Type_argument_list_cannot_be_empty); + } + return false; + } + + function checkGrammarTypeArguments(node: Node, typeArguments: NodeArray | undefined): boolean { + return checkGrammarForDisallowedTrailingComma(typeArguments) || + checkGrammarForAtLeastOneTypeArgument(node, typeArguments); + } + + function checkGrammarTaggedTemplateChain(node: TaggedTemplateExpression): boolean { + if (node.questionDotToken || node.flags & NodeFlags.OptionalChain) { + return grammarErrorOnNode(node.template, Diagnostics.Tagged_template_expressions_are_not_permitted_in_an_optional_chain); + } + return false; + } + + function checkGrammarHeritageClause(node: HeritageClause): boolean { + const types = node.types; + if (checkGrammarForDisallowedTrailingComma(types)) { + return true; + } + if (types && types.length === 0) { + const listType = tokenToString(node.token); + return grammarErrorAtPos(node, types.pos, 0, Diagnostics._0_list_cannot_be_empty, listType); + } + return some(types, checkGrammarExpressionWithTypeArguments); + } + + function checkGrammarExpressionWithTypeArguments(node: ExpressionWithTypeArguments | TypeQueryNode) { + if (isExpressionWithTypeArguments(node) && isImportKeyword(node.expression) && node.typeArguments) { + return grammarErrorOnNode(node, Diagnostics.This_use_of_import_is_invalid_import_calls_can_be_written_but_they_must_have_parentheses_and_cannot_have_type_arguments); + } + return checkGrammarTypeArguments(node, node.typeArguments); + } + + function checkGrammarClassDeclarationHeritageClauses(node: ClassLikeDeclaration) { + let seenExtendsClause = false; + let seenImplementsClause = false; + + if (!checkGrammarModifiers(node) && node.heritageClauses) { + for (const heritageClause of node.heritageClauses) { + if (heritageClause.token === SyntaxKind.ExtendsKeyword) { + if (seenExtendsClause) { + return grammarErrorOnFirstToken(heritageClause, Diagnostics.extends_clause_already_seen); + } + + if (seenImplementsClause) { + return grammarErrorOnFirstToken(heritageClause, Diagnostics.extends_clause_must_precede_implements_clause); + } + + if (heritageClause.types.length > 1) { + return grammarErrorOnFirstToken(heritageClause.types[1], Diagnostics.Classes_can_only_extend_a_single_class); + } + + seenExtendsClause = true; + } + else { + Debug.assert(heritageClause.token === SyntaxKind.ImplementsKeyword); + if (seenImplementsClause) { + return grammarErrorOnFirstToken(heritageClause, Diagnostics.implements_clause_already_seen); + } + + seenImplementsClause = true; + } + + // Grammar checking heritageClause inside class declaration + checkGrammarHeritageClause(heritageClause); + } + } + } + + function checkGrammarInterfaceDeclaration(node: InterfaceDeclaration) { + let seenExtendsClause = false; + + if (node.heritageClauses) { + for (const heritageClause of node.heritageClauses) { + if (heritageClause.token === SyntaxKind.ExtendsKeyword) { + if (seenExtendsClause) { + return grammarErrorOnFirstToken(heritageClause, Diagnostics.extends_clause_already_seen); + } + + seenExtendsClause = true; + } + else { + Debug.assert(heritageClause.token === SyntaxKind.ImplementsKeyword); + return grammarErrorOnFirstToken(heritageClause, Diagnostics.Interface_declaration_cannot_have_implements_clause); + } + + // Grammar checking heritageClause inside class declaration + checkGrammarHeritageClause(heritageClause); + } + } + return false; + } + + function checkGrammarComputedPropertyName(node: Node): boolean { + // If node is not a computedPropertyName, just skip the grammar checking + if (node.kind !== SyntaxKind.ComputedPropertyName) { + return false; + } + + const computedPropertyName = node as ComputedPropertyName; + if (computedPropertyName.expression.kind === SyntaxKind.BinaryExpression && (computedPropertyName.expression as BinaryExpression).operatorToken.kind === SyntaxKind.CommaToken) { + return grammarErrorOnNode(computedPropertyName.expression, Diagnostics.A_comma_expression_is_not_allowed_in_a_computed_property_name); + } + return false; + } + + function checkGrammarForGenerator(node: FunctionLikeDeclaration) { + if (node.asteriskToken) { + Debug.assert( + node.kind === SyntaxKind.FunctionDeclaration || + node.kind === SyntaxKind.FunctionExpression || + node.kind === SyntaxKind.MethodDeclaration, + ); + if (node.flags & NodeFlags.Ambient) { + return grammarErrorOnNode(node.asteriskToken, Diagnostics.Generators_are_not_allowed_in_an_ambient_context); + } + if (!node.body) { + return grammarErrorOnNode(node.asteriskToken, Diagnostics.An_overload_signature_cannot_be_declared_as_a_generator); + } + } + } + + function checkGrammarForInvalidQuestionMark(questionToken: QuestionToken | undefined, message: DiagnosticMessage): boolean { + return !!questionToken && grammarErrorOnNode(questionToken, message); + } + + function checkGrammarForInvalidExclamationToken(exclamationToken: ExclamationToken | undefined, message: DiagnosticMessage): boolean { + return !!exclamationToken && grammarErrorOnNode(exclamationToken, message); + } + + function checkGrammarObjectLiteralExpression(node: ObjectLiteralExpression, inDestructuring: boolean) { + const seen = new Map<__String, DeclarationMeaning>(); + + for (const prop of node.properties) { + if (prop.kind === SyntaxKind.SpreadAssignment) { + if (inDestructuring) { + // a rest property cannot be destructured any further + const expression = skipParentheses(prop.expression); + if (isArrayLiteralExpression(expression) || isObjectLiteralExpression(expression)) { + return grammarErrorOnNode(prop.expression, Diagnostics.A_rest_element_cannot_contain_a_binding_pattern); + } + } + continue; + } + const name = prop.name; + if (name.kind === SyntaxKind.ComputedPropertyName) { + // If the name is not a ComputedPropertyName, the grammar checking will skip it + checkGrammarComputedPropertyName(name); + } + + if (prop.kind === SyntaxKind.ShorthandPropertyAssignment && !inDestructuring && prop.objectAssignmentInitializer) { + // having objectAssignmentInitializer is only valid in ObjectAssignmentPattern + // outside of destructuring it is a syntax error + grammarErrorOnNode(prop.equalsToken!, Diagnostics.Did_you_mean_to_use_a_Colon_An_can_only_follow_a_property_name_when_the_containing_object_literal_is_part_of_a_destructuring_pattern); + } + + if (name.kind === SyntaxKind.PrivateIdentifier) { + grammarErrorOnNode(name, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + + // Modifiers are never allowed on properties except for 'async' on a method declaration + if (canHaveModifiers(prop) && prop.modifiers) { + for (const mod of prop.modifiers) { + if (isModifier(mod) && (mod.kind !== SyntaxKind.AsyncKeyword || prop.kind !== SyntaxKind.MethodDeclaration)) { + grammarErrorOnNode(mod, Diagnostics._0_modifier_cannot_be_used_here, getTextOfNode(mod)); + } + } + } + else if (canHaveIllegalModifiers(prop) && prop.modifiers) { + for (const mod of prop.modifiers) { + if (isModifier(mod)) { + grammarErrorOnNode(mod, Diagnostics._0_modifier_cannot_be_used_here, getTextOfNode(mod)); + } + } + } + + // ECMA-262 11.1.5 Object Initializer + // If previous is not undefined then throw a SyntaxError exception if any of the following conditions are true + // a.This production is contained in strict code and IsDataDescriptor(previous) is true and + // IsDataDescriptor(propId.descriptor) is true. + // b.IsDataDescriptor(previous) is true and IsAccessorDescriptor(propId.descriptor) is true. + // c.IsAccessorDescriptor(previous) is true and IsDataDescriptor(propId.descriptor) is true. + // d.IsAccessorDescriptor(previous) is true and IsAccessorDescriptor(propId.descriptor) is true + // and either both previous and propId.descriptor have[[Get]] fields or both previous and propId.descriptor have[[Set]] fields + let currentKind: DeclarationMeaning; + switch (prop.kind) { + case SyntaxKind.ShorthandPropertyAssignment: + case SyntaxKind.PropertyAssignment: + // Grammar checking for computedPropertyName and shorthandPropertyAssignment + checkGrammarForInvalidExclamationToken(prop.exclamationToken, Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context); + checkGrammarForInvalidQuestionMark(prop.questionToken, Diagnostics.An_object_member_cannot_be_declared_optional); + if (name.kind === SyntaxKind.NumericLiteral) { + checkGrammarNumericLiteral(name); + } + currentKind = DeclarationMeaning.PropertyAssignment; + break; + case SyntaxKind.MethodDeclaration: + currentKind = DeclarationMeaning.Method; + break; + case SyntaxKind.GetAccessor: + currentKind = DeclarationMeaning.GetAccessor; + break; + case SyntaxKind.SetAccessor: + currentKind = DeclarationMeaning.SetAccessor; + break; + default: + Debug.assertNever(prop, "Unexpected syntax kind:" + (prop as Node).kind); + } + + if (!inDestructuring) { + const effectiveName = getEffectivePropertyNameForPropertyNameNode(name); + if (effectiveName === undefined) { + continue; + } + + const existingKind = seen.get(effectiveName); + if (!existingKind) { + seen.set(effectiveName, currentKind); + } + else { + if ((currentKind & DeclarationMeaning.Method) && (existingKind & DeclarationMeaning.Method)) { + grammarErrorOnNode(name, Diagnostics.Duplicate_identifier_0, getTextOfNode(name)); + } + else if ((currentKind & DeclarationMeaning.PropertyAssignment) && (existingKind & DeclarationMeaning.PropertyAssignment)) { + grammarErrorOnNode(name, Diagnostics.An_object_literal_cannot_have_multiple_properties_with_the_same_name, getTextOfNode(name)); + } + else if ((currentKind & DeclarationMeaning.GetOrSetAccessor) && (existingKind & DeclarationMeaning.GetOrSetAccessor)) { + if (existingKind !== DeclarationMeaning.GetOrSetAccessor && currentKind !== existingKind) { + seen.set(effectiveName, currentKind | existingKind); + } + else { + return grammarErrorOnNode(name, Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name); + } + } + else { + return grammarErrorOnNode(name, Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name); + } + } + } + } + } + + function checkGrammarJsxElement(node: JsxOpeningLikeElement) { + checkGrammarJsxName(node.tagName); + checkGrammarTypeArguments(node, node.typeArguments); + const seen = new Map<__String, boolean>(); + + for (const attr of node.attributes.properties) { + if (attr.kind === SyntaxKind.JsxSpreadAttribute) { + continue; + } + + const { name, initializer } = attr; + const escapedText = getEscapedTextOfJsxAttributeName(name); + if (!seen.get(escapedText)) { + seen.set(escapedText, true); + } + else { + return grammarErrorOnNode(name, Diagnostics.JSX_elements_cannot_have_multiple_attributes_with_the_same_name); + } + + if (initializer && initializer.kind === SyntaxKind.JsxExpression && !initializer.expression) { + return grammarErrorOnNode(initializer, Diagnostics.JSX_attributes_must_only_be_assigned_a_non_empty_expression); + } + } + } + + function checkGrammarJsxName(node: JsxTagNameExpression) { + if (isPropertyAccessExpression(node) && isJsxNamespacedName(node.expression)) { + return grammarErrorOnNode(node.expression, Diagnostics.JSX_property_access_expressions_cannot_include_JSX_namespace_names); + } + if (isJsxNamespacedName(node) && getJSXTransformEnabled(compilerOptions) && !isIntrinsicJsxName(node.namespace.escapedText)) { + return grammarErrorOnNode(node, Diagnostics.React_components_cannot_include_JSX_namespace_names); + } + } + + function checkGrammarJsxExpression(node: JsxExpression) { + if (node.expression && isCommaSequence(node.expression)) { + return grammarErrorOnNode(node.expression, Diagnostics.JSX_expressions_may_not_use_the_comma_operator_Did_you_mean_to_write_an_array); + } + } + + function checkGrammarForInOrForOfStatement(forInOrOfStatement: ForInOrOfStatement): boolean { + if (checkGrammarStatementInAmbientContext(forInOrOfStatement)) { + return true; + } + + if (forInOrOfStatement.kind === SyntaxKind.ForOfStatement && forInOrOfStatement.awaitModifier) { + if (!(forInOrOfStatement.flags & NodeFlags.AwaitContext)) { + const sourceFile = getSourceFileOfNode(forInOrOfStatement); + if (isInTopLevelContext(forInOrOfStatement)) { + if (!hasParseDiagnostics(sourceFile)) { + if (!isEffectiveExternalModule(sourceFile, compilerOptions)) { + diagnostics.add(createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.for_await_loops_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module)); + } + switch (moduleKind) { + case ModuleKind.Node16: + case ModuleKind.NodeNext: + if (sourceFile.impliedNodeFormat === ModuleKind.CommonJS) { + diagnostics.add( + createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.The_current_file_is_a_CommonJS_module_and_cannot_use_await_at_the_top_level), + ); + break; + } + // fallthrough + case ModuleKind.ES2022: + case ModuleKind.ESNext: + case ModuleKind.System: + if (languageVersion >= ScriptTarget.ES2017) { + break; + } + // fallthrough + default: + diagnostics.add( + createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.Top_level_for_await_loops_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_nodenext_or_preserve_and_the_target_option_is_set_to_es2017_or_higher), + ); + break; + } + } + } + else { + // use of 'for-await-of' in non-async function + if (!hasParseDiagnostics(sourceFile)) { + const diagnostic = createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.for_await_loops_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules); + const func = getContainingFunction(forInOrOfStatement); + if (func && func.kind !== SyntaxKind.Constructor) { + Debug.assert((getFunctionFlags(func) & FunctionFlags.Async) === 0, "Enclosing function should never be an async function."); + const relatedInfo = createDiagnosticForNode(func, Diagnostics.Did_you_mean_to_mark_this_function_as_async); + addRelatedInfo(diagnostic, relatedInfo); + } + diagnostics.add(diagnostic); + return true; + } + } + } + } + + if ( + isForOfStatement(forInOrOfStatement) && !(forInOrOfStatement.flags & NodeFlags.AwaitContext) && + isIdentifier(forInOrOfStatement.initializer) && forInOrOfStatement.initializer.escapedText === "async" + ) { + grammarErrorOnNode(forInOrOfStatement.initializer, Diagnostics.The_left_hand_side_of_a_for_of_statement_may_not_be_async); + return false; + } + + if (forInOrOfStatement.initializer.kind === SyntaxKind.VariableDeclarationList) { + const variableList = forInOrOfStatement.initializer as VariableDeclarationList; + if (!checkGrammarVariableDeclarationList(variableList)) { + const declarations = variableList.declarations; + + // declarations.length can be zero if there is an error in variable declaration in for-of or for-in + // See http://www.ecma-international.org/ecma-262/6.0/#sec-for-in-and-for-of-statements for details + // For example: + // var let = 10; + // for (let of [1,2,3]) {} // this is invalid ES6 syntax + // for (let in [1,2,3]) {} // this is invalid ES6 syntax + // We will then want to skip on grammar checking on variableList declaration + if (!declarations.length) { + return false; + } + + if (declarations.length > 1) { + const diagnostic = forInOrOfStatement.kind === SyntaxKind.ForInStatement + ? Diagnostics.Only_a_single_variable_declaration_is_allowed_in_a_for_in_statement + : Diagnostics.Only_a_single_variable_declaration_is_allowed_in_a_for_of_statement; + return grammarErrorOnFirstToken(variableList.declarations[1], diagnostic); + } + const firstDeclaration = declarations[0]; + + if (firstDeclaration.initializer) { + const diagnostic = forInOrOfStatement.kind === SyntaxKind.ForInStatement + ? Diagnostics.The_variable_declaration_of_a_for_in_statement_cannot_have_an_initializer + : Diagnostics.The_variable_declaration_of_a_for_of_statement_cannot_have_an_initializer; + return grammarErrorOnNode(firstDeclaration.name, diagnostic); + } + if (firstDeclaration.type) { + const diagnostic = forInOrOfStatement.kind === SyntaxKind.ForInStatement + ? Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_use_a_type_annotation + : Diagnostics.The_left_hand_side_of_a_for_of_statement_cannot_use_a_type_annotation; + return grammarErrorOnNode(firstDeclaration, diagnostic); + } + } + } + + return false; + } + + function checkGrammarAccessor(accessor: AccessorDeclaration): boolean { + if (!(accessor.flags & NodeFlags.Ambient) && (accessor.parent.kind !== SyntaxKind.TypeLiteral) && (accessor.parent.kind !== SyntaxKind.InterfaceDeclaration)) { + if (languageVersion < ScriptTarget.ES2015 && isPrivateIdentifier(accessor.name)) { + return grammarErrorOnNode(accessor.name, Diagnostics.Private_identifiers_are_only_available_when_targeting_ECMAScript_2015_and_higher); + } + if (accessor.body === undefined && !hasSyntacticModifier(accessor, ModifierFlags.Abstract)) { + return grammarErrorAtPos(accessor, accessor.end - 1, ";".length, Diagnostics._0_expected, "{"); + } + } + if (accessor.body) { + if (hasSyntacticModifier(accessor, ModifierFlags.Abstract)) { + return grammarErrorOnNode(accessor, Diagnostics.An_abstract_accessor_cannot_have_an_implementation); + } + if (accessor.parent.kind === SyntaxKind.TypeLiteral || accessor.parent.kind === SyntaxKind.InterfaceDeclaration) { + return grammarErrorOnNode(accessor.body, Diagnostics.An_implementation_cannot_be_declared_in_ambient_contexts); + } + } + if (accessor.typeParameters) { + return grammarErrorOnNode(accessor.name, Diagnostics.An_accessor_cannot_have_type_parameters); + } + if (!doesAccessorHaveCorrectParameterCount(accessor)) { + return grammarErrorOnNode( + accessor.name, + accessor.kind === SyntaxKind.GetAccessor ? + Diagnostics.A_get_accessor_cannot_have_parameters : + Diagnostics.A_set_accessor_must_have_exactly_one_parameter, + ); + } + if (accessor.kind === SyntaxKind.SetAccessor) { + if (accessor.type) { + return grammarErrorOnNode(accessor.name, Diagnostics.A_set_accessor_cannot_have_a_return_type_annotation); + } + const parameter = Debug.checkDefined(getSetAccessorValueParameter(accessor), "Return value does not match parameter count assertion."); + if (parameter.dotDotDotToken) { + return grammarErrorOnNode(parameter.dotDotDotToken, Diagnostics.A_set_accessor_cannot_have_rest_parameter); + } + if (parameter.questionToken) { + return grammarErrorOnNode(parameter.questionToken, Diagnostics.A_set_accessor_cannot_have_an_optional_parameter); + } + if (parameter.initializer) { + return grammarErrorOnNode(accessor.name, Diagnostics.A_set_accessor_parameter_cannot_have_an_initializer); + } + } + return false; + } + + /** Does the accessor have the right number of parameters? + * A get accessor has no parameters or a single `this` parameter. + * A set accessor has one parameter or a `this` parameter and one more parameter. + */ + function doesAccessorHaveCorrectParameterCount(accessor: AccessorDeclaration) { + return getAccessorThisParameter(accessor) || accessor.parameters.length === (accessor.kind === SyntaxKind.GetAccessor ? 0 : 1); + } + + function getAccessorThisParameter(accessor: AccessorDeclaration): ParameterDeclaration | undefined { + if (accessor.parameters.length === (accessor.kind === SyntaxKind.GetAccessor ? 1 : 2)) { + return getThisParameter(accessor); + } + } + + function checkGrammarTypeOperatorNode(node: TypeOperatorNode) { + if (node.operator === SyntaxKind.UniqueKeyword) { + if (node.type.kind !== SyntaxKind.SymbolKeyword) { + return grammarErrorOnNode(node.type, Diagnostics._0_expected, tokenToString(SyntaxKind.SymbolKeyword)); + } + let parent = walkUpParenthesizedTypes(node.parent); + if (isInJSFile(parent) && isJSDocTypeExpression(parent)) { + const host = getJSDocHost(parent); + if (host) { + parent = getSingleVariableOfVariableStatement(host) || host; + } + } + switch (parent.kind) { + case SyntaxKind.VariableDeclaration: + const decl = parent as VariableDeclaration; + if (decl.name.kind !== SyntaxKind.Identifier) { + return grammarErrorOnNode(node, Diagnostics.unique_symbol_types_may_not_be_used_on_a_variable_declaration_with_a_binding_name); + } + if (!isVariableDeclarationInVariableStatement(decl)) { + return grammarErrorOnNode(node, Diagnostics.unique_symbol_types_are_only_allowed_on_variables_in_a_variable_statement); + } + if (!(decl.parent.flags & NodeFlags.Const)) { + return grammarErrorOnNode((parent as VariableDeclaration).name, Diagnostics.A_variable_whose_type_is_a_unique_symbol_type_must_be_const); + } + break; + + case SyntaxKind.PropertyDeclaration: + if ( + !isStatic(parent) || + !hasEffectiveReadonlyModifier(parent) + ) { + return grammarErrorOnNode((parent as PropertyDeclaration).name, Diagnostics.A_property_of_a_class_whose_type_is_a_unique_symbol_type_must_be_both_static_and_readonly); + } + break; + + case SyntaxKind.PropertySignature: + if (!hasSyntacticModifier(parent, ModifierFlags.Readonly)) { + return grammarErrorOnNode((parent as PropertySignature).name, Diagnostics.A_property_of_an_interface_or_type_literal_whose_type_is_a_unique_symbol_type_must_be_readonly); + } + break; + + default: + return grammarErrorOnNode(node, Diagnostics.unique_symbol_types_are_not_allowed_here); + } + } + else if (node.operator === SyntaxKind.ReadonlyKeyword) { + if (node.type.kind !== SyntaxKind.ArrayType && node.type.kind !== SyntaxKind.TupleType) { + return grammarErrorOnFirstToken(node, Diagnostics.readonly_type_modifier_is_only_permitted_on_array_and_tuple_literal_types, tokenToString(SyntaxKind.SymbolKeyword)); + } + } + } + + function checkGrammarForInvalidDynamicName(node: DeclarationName, message: DiagnosticMessage) { + if (isNonBindableDynamicName(node)) { + return grammarErrorOnNode(node, message); + } + } + + function checkGrammarMethod(node: MethodDeclaration | MethodSignature) { + if (checkGrammarFunctionLikeDeclaration(node)) { + return true; + } + + if (node.kind === SyntaxKind.MethodDeclaration) { + if (node.parent.kind === SyntaxKind.ObjectLiteralExpression) { + // We only disallow modifier on a method declaration if it is a property of object-literal-expression + if (node.modifiers && !(node.modifiers.length === 1 && first(node.modifiers).kind === SyntaxKind.AsyncKeyword)) { + return grammarErrorOnFirstToken(node, Diagnostics.Modifiers_cannot_appear_here); + } + else if (checkGrammarForInvalidQuestionMark(node.questionToken, Diagnostics.An_object_member_cannot_be_declared_optional)) { + return true; + } + else if (checkGrammarForInvalidExclamationToken(node.exclamationToken, Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context)) { + return true; + } + else if (node.body === undefined) { + return grammarErrorAtPos(node, node.end - 1, ";".length, Diagnostics._0_expected, "{"); + } + } + if (checkGrammarForGenerator(node)) { + return true; + } + } + + if (isClassLike(node.parent)) { + if (languageVersion < ScriptTarget.ES2015 && isPrivateIdentifier(node.name)) { + return grammarErrorOnNode(node.name, Diagnostics.Private_identifiers_are_only_available_when_targeting_ECMAScript_2015_and_higher); + } + // Technically, computed properties in ambient contexts is disallowed + // for property declarations and accessors too, not just methods. + // However, property declarations disallow computed names in general, + // and accessors are not allowed in ambient contexts in general, + // so this error only really matters for methods. + if (node.flags & NodeFlags.Ambient) { + return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_an_ambient_context_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); + } + else if (node.kind === SyntaxKind.MethodDeclaration && !node.body) { + return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_method_overload_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); + } + } + else if (node.parent.kind === SyntaxKind.InterfaceDeclaration) { + return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_an_interface_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); + } + else if (node.parent.kind === SyntaxKind.TypeLiteral) { + return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_type_literal_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); + } + } + + function checkGrammarBreakOrContinueStatement(node: BreakOrContinueStatement): boolean { + let current: Node = node; + while (current) { + if (isFunctionLikeOrClassStaticBlockDeclaration(current)) { + return grammarErrorOnNode(node, Diagnostics.Jump_target_cannot_cross_function_boundary); + } + + switch (current.kind) { + case SyntaxKind.LabeledStatement: + if (node.label && (current as LabeledStatement).label.escapedText === node.label.escapedText) { + // found matching label - verify that label usage is correct + // continue can only target labels that are on iteration statements + const isMisplacedContinueLabel = node.kind === SyntaxKind.ContinueStatement + && !isIterationStatement((current as LabeledStatement).statement, /*lookInLabeledStatements*/ true); + + if (isMisplacedContinueLabel) { + return grammarErrorOnNode(node, Diagnostics.A_continue_statement_can_only_jump_to_a_label_of_an_enclosing_iteration_statement); + } + + return false; + } + break; + case SyntaxKind.SwitchStatement: + if (node.kind === SyntaxKind.BreakStatement && !node.label) { + // unlabeled break within switch statement - ok + return false; + } + break; + default: + if (isIterationStatement(current, /*lookInLabeledStatements*/ false) && !node.label) { + // unlabeled break or continue within iteration statement - ok + return false; + } + break; + } + + current = current.parent; + } + + if (node.label) { + const message = node.kind === SyntaxKind.BreakStatement + ? Diagnostics.A_break_statement_can_only_jump_to_a_label_of_an_enclosing_statement + : Diagnostics.A_continue_statement_can_only_jump_to_a_label_of_an_enclosing_iteration_statement; + + return grammarErrorOnNode(node, message); + } + else { + const message = node.kind === SyntaxKind.BreakStatement + ? Diagnostics.A_break_statement_can_only_be_used_within_an_enclosing_iteration_or_switch_statement + : Diagnostics.A_continue_statement_can_only_be_used_within_an_enclosing_iteration_statement; + return grammarErrorOnNode(node, message); + } + } + + function checkGrammarBindingElement(node: BindingElement) { + if (node.dotDotDotToken) { + const elements = node.parent.elements; + if (node !== last(elements)) { + return grammarErrorOnNode(node, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); + } + checkGrammarForDisallowedTrailingComma(elements, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + + if (node.propertyName) { + return grammarErrorOnNode(node.name, Diagnostics.A_rest_element_cannot_have_a_property_name); + } + } + + if (node.dotDotDotToken && node.initializer) { + // Error on equals token which immediately precedes the initializer + return grammarErrorAtPos(node, node.initializer.pos - 1, 1, Diagnostics.A_rest_element_cannot_have_an_initializer); + } + } + + function isStringOrNumberLiteralExpression(expr: Expression) { + return isStringOrNumericLiteralLike(expr) || + expr.kind === SyntaxKind.PrefixUnaryExpression && (expr as PrefixUnaryExpression).operator === SyntaxKind.MinusToken && + (expr as PrefixUnaryExpression).operand.kind === SyntaxKind.NumericLiteral; + } + + function isBigIntLiteralExpression(expr: Expression) { + return expr.kind === SyntaxKind.BigIntLiteral || + expr.kind === SyntaxKind.PrefixUnaryExpression && (expr as PrefixUnaryExpression).operator === SyntaxKind.MinusToken && + (expr as PrefixUnaryExpression).operand.kind === SyntaxKind.BigIntLiteral; + } + + function isSimpleLiteralEnumReference(expr: Expression) { + if ( + (isPropertyAccessExpression(expr) || (isElementAccessExpression(expr) && isStringOrNumberLiteralExpression(expr.argumentExpression))) && + isEntityNameExpression(expr.expression) + ) { + return !!(checkExpressionCached(expr).flags & TypeFlags.EnumLike); + } + } + + function checkAmbientInitializer(node: VariableDeclaration | PropertyDeclaration | PropertySignature) { + const initializer = node.initializer; + if (initializer) { + const isInvalidInitializer = !( + isStringOrNumberLiteralExpression(initializer) || + isSimpleLiteralEnumReference(initializer) || + initializer.kind === SyntaxKind.TrueKeyword || initializer.kind === SyntaxKind.FalseKeyword || + isBigIntLiteralExpression(initializer) + ); + const isConstOrReadonly = isDeclarationReadonly(node) || isVariableDeclaration(node) && (isVarConstLike(node)); + if (isConstOrReadonly && !node.type) { + if (isInvalidInitializer) { + return grammarErrorOnNode(initializer, Diagnostics.A_const_initializer_in_an_ambient_context_must_be_a_string_or_numeric_literal_or_literal_enum_reference); + } + } + else { + return grammarErrorOnNode(initializer, Diagnostics.Initializers_are_not_allowed_in_ambient_contexts); + } + } + } + + function checkGrammarVariableDeclaration(node: VariableDeclaration) { + const nodeFlags = getCombinedNodeFlagsCached(node); + const blockScopeKind = nodeFlags & NodeFlags.BlockScoped; + if (isBindingPattern(node.name)) { + switch (blockScopeKind) { + case NodeFlags.AwaitUsing: + return grammarErrorOnNode(node, Diagnostics._0_declarations_may_not_have_binding_patterns, "await using"); + case NodeFlags.Using: + return grammarErrorOnNode(node, Diagnostics._0_declarations_may_not_have_binding_patterns, "using"); + } + } + + if (node.parent.parent.kind !== SyntaxKind.ForInStatement && node.parent.parent.kind !== SyntaxKind.ForOfStatement) { + if (nodeFlags & NodeFlags.Ambient) { + checkAmbientInitializer(node); + } + else if (!node.initializer) { + if (isBindingPattern(node.name) && !isBindingPattern(node.parent)) { + return grammarErrorOnNode(node, Diagnostics.A_destructuring_declaration_must_have_an_initializer); + } + switch (blockScopeKind) { + case NodeFlags.AwaitUsing: + return grammarErrorOnNode(node, Diagnostics._0_declarations_must_be_initialized, "await using"); + case NodeFlags.Using: + return grammarErrorOnNode(node, Diagnostics._0_declarations_must_be_initialized, "using"); + case NodeFlags.Const: + return grammarErrorOnNode(node, Diagnostics._0_declarations_must_be_initialized, "const"); + } + } + } + + if (node.exclamationToken && (node.parent.parent.kind !== SyntaxKind.VariableStatement || !node.type || node.initializer || nodeFlags & NodeFlags.Ambient)) { + const message = node.initializer + ? Diagnostics.Declarations_with_initializers_cannot_also_have_definite_assignment_assertions + : !node.type + ? Diagnostics.Declarations_with_definite_assignment_assertions_must_also_have_type_annotations + : Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context; + return grammarErrorOnNode(node.exclamationToken, message); + } + + if ( + (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) && moduleKind !== ModuleKind.System && + !(node.parent.parent.flags & NodeFlags.Ambient) && hasSyntacticModifier(node.parent.parent, ModifierFlags.Export) + ) { + checkESModuleMarker(node.name); + } + + // 1. LexicalDeclaration : LetOrConst BindingList ; + // It is a Syntax Error if the BoundNames of BindingList contains "let". + // 2. ForDeclaration: ForDeclaration : LetOrConst ForBinding + // It is a Syntax Error if the BoundNames of ForDeclaration contains "let". + + // It is a SyntaxError if a VariableDeclaration or VariableDeclarationNoIn occurs within strict code + // and its Identifier is eval or arguments + return !!blockScopeKind && checkGrammarNameInLetOrConstDeclarations(node.name); + } + + function checkESModuleMarker(name: Identifier | BindingPattern): boolean { + if (name.kind === SyntaxKind.Identifier) { + if (idText(name) === "__esModule") { + return grammarErrorOnNodeSkippedOn("noEmit", name, Diagnostics.Identifier_expected_esModule_is_reserved_as_an_exported_marker_when_transforming_ECMAScript_modules); + } + } + else { + const elements = name.elements; + for (const element of elements) { + if (!isOmittedExpression(element)) { + return checkESModuleMarker(element.name); + } + } + } + return false; + } + + function checkGrammarNameInLetOrConstDeclarations(name: Identifier | BindingPattern): boolean { + if (name.kind === SyntaxKind.Identifier) { + if (name.escapedText === "let") { + return grammarErrorOnNode(name, Diagnostics.let_is_not_allowed_to_be_used_as_a_name_in_let_or_const_declarations); + } + } + else { + const elements = name.elements; + for (const element of elements) { + if (!isOmittedExpression(element)) { + checkGrammarNameInLetOrConstDeclarations(element.name); + } + } + } + return false; + } + + function checkGrammarVariableDeclarationList(declarationList: VariableDeclarationList): boolean { + const declarations = declarationList.declarations; + if (checkGrammarForDisallowedTrailingComma(declarationList.declarations)) { + return true; + } + + if (!declarationList.declarations.length) { + return grammarErrorAtPos(declarationList, declarations.pos, declarations.end - declarations.pos, Diagnostics.Variable_declaration_list_cannot_be_empty); + } + + const blockScopeFlags = declarationList.flags & NodeFlags.BlockScoped; + if ((blockScopeFlags === NodeFlags.Using || blockScopeFlags === NodeFlags.AwaitUsing) && isForInStatement(declarationList.parent)) { + return grammarErrorOnNode( + declarationList, + blockScopeFlags === NodeFlags.Using ? + Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_a_using_declaration : + Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_an_await_using_declaration, + ); + } + + if (blockScopeFlags === NodeFlags.AwaitUsing) { + return checkAwaitGrammar(declarationList); + } + + return false; + } + + function allowLetAndConstDeclarations(parent: Node): boolean { + switch (parent.kind) { + case SyntaxKind.IfStatement: + case SyntaxKind.DoStatement: + case SyntaxKind.WhileStatement: + case SyntaxKind.WithStatement: + case SyntaxKind.ForStatement: + case SyntaxKind.ForInStatement: + case SyntaxKind.ForOfStatement: + return false; + case SyntaxKind.LabeledStatement: + return allowLetAndConstDeclarations(parent.parent); + } + + return true; + } + + function checkGrammarForDisallowedBlockScopedVariableStatement(node: VariableStatement) { + if (!allowLetAndConstDeclarations(node.parent)) { + const blockScopeKind = getCombinedNodeFlagsCached(node.declarationList) & NodeFlags.BlockScoped; + if (blockScopeKind) { + const keyword = blockScopeKind === NodeFlags.Let ? "let" : + blockScopeKind === NodeFlags.Const ? "const" : + blockScopeKind === NodeFlags.Using ? "using" : + blockScopeKind === NodeFlags.AwaitUsing ? "await using" : + Debug.fail("Unknown BlockScope flag"); + return grammarErrorOnNode(node, Diagnostics._0_declarations_can_only_be_declared_inside_a_block, keyword); + } + } + } + + function checkGrammarMetaProperty(node: MetaProperty) { + const escapedText = node.name.escapedText; + switch (node.keywordToken) { + case SyntaxKind.NewKeyword: + if (escapedText !== "target") { + return grammarErrorOnNode(node.name, Diagnostics._0_is_not_a_valid_meta_property_for_keyword_1_Did_you_mean_2, unescapeLeadingUnderscores(node.name.escapedText), tokenToString(node.keywordToken), "target"); + } + break; + case SyntaxKind.ImportKeyword: + if (escapedText !== "meta") { + return grammarErrorOnNode(node.name, Diagnostics._0_is_not_a_valid_meta_property_for_keyword_1_Did_you_mean_2, unescapeLeadingUnderscores(node.name.escapedText), tokenToString(node.keywordToken), "meta"); + } + break; + } + } + + function hasParseDiagnostics(sourceFile: SourceFile): boolean { + return sourceFile.parseDiagnostics.length > 0; + } + + function grammarErrorOnFirstToken(node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + const span = getSpanOfTokenAtPosition(sourceFile, node.pos); + diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, message, ...args)); + return true; + } + return false; + } + + function grammarErrorAtPos(nodeForSourceFile: Node, start: number, length: number, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(nodeForSourceFile); + if (!hasParseDiagnostics(sourceFile)) { + diagnostics.add(createFileDiagnostic(sourceFile, start, length, message, ...args)); + return true; + } + return false; + } + + function grammarErrorOnNodeSkippedOn(key: keyof CompilerOptions, node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + errorSkippedOn(key, node, message, ...args); + return true; + } + return false; + } + + function grammarErrorOnNode(node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + diagnostics.add(createDiagnosticForNode(node, message, ...args)); + return true; + } + return false; + } + + function checkGrammarConstructorTypeParameters(node: ConstructorDeclaration) { + const jsdocTypeParameters = isInJSFile(node) ? getJSDocTypeParameterDeclarations(node) : undefined; + const range = node.typeParameters || jsdocTypeParameters && firstOrUndefined(jsdocTypeParameters); + if (range) { + const pos = range.pos === range.end ? range.pos : skipTrivia(getSourceFileOfNode(node).text, range.pos); + return grammarErrorAtPos(node, pos, range.end - pos, Diagnostics.Type_parameters_cannot_appear_on_a_constructor_declaration); + } + } + + function checkGrammarConstructorTypeAnnotation(node: ConstructorDeclaration) { + const type = node.type || getEffectiveReturnTypeNode(node); + if (type) { + return grammarErrorOnNode(type, Diagnostics.Type_annotation_cannot_appear_on_a_constructor_declaration); + } + } + + function checkGrammarProperty(node: PropertyDeclaration | PropertySignature) { + if (isComputedPropertyName(node.name) && isBinaryExpression(node.name.expression) && node.name.expression.operatorToken.kind === SyntaxKind.InKeyword) { + return grammarErrorOnNode(node.parent.members[0], Diagnostics.A_mapped_type_may_not_declare_properties_or_methods); + } + if (isClassLike(node.parent)) { + if (isStringLiteral(node.name) && node.name.text === "constructor") { + return grammarErrorOnNode(node.name, Diagnostics.Classes_may_not_have_a_field_named_constructor); + } + if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_class_property_declaration_must_have_a_simple_literal_type_or_a_unique_symbol_type)) { + return true; + } + if (languageVersion < ScriptTarget.ES2015 && isPrivateIdentifier(node.name)) { + return grammarErrorOnNode(node.name, Diagnostics.Private_identifiers_are_only_available_when_targeting_ECMAScript_2015_and_higher); + } + if (languageVersion < ScriptTarget.ES2015 && isAutoAccessorPropertyDeclaration(node)) { + return grammarErrorOnNode(node.name, Diagnostics.Properties_with_the_accessor_modifier_are_only_available_when_targeting_ECMAScript_2015_and_higher); + } + if (isAutoAccessorPropertyDeclaration(node) && checkGrammarForInvalidQuestionMark(node.questionToken, Diagnostics.An_accessor_property_cannot_be_declared_optional)) { + return true; + } + } + else if (node.parent.kind === SyntaxKind.InterfaceDeclaration) { + if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_an_interface_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type)) { + return true; + } + + // Interfaces cannot contain property declarations + Debug.assertNode(node, isPropertySignature); + if (node.initializer) { + return grammarErrorOnNode(node.initializer, Diagnostics.An_interface_property_cannot_have_an_initializer); + } + } + else if (isTypeLiteralNode(node.parent)) { + if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_type_literal_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type)) { + return true; + } + // Type literals cannot contain property declarations + Debug.assertNode(node, isPropertySignature); + if (node.initializer) { + return grammarErrorOnNode(node.initializer, Diagnostics.A_type_literal_property_cannot_have_an_initializer); + } + } + + if (node.flags & NodeFlags.Ambient) { + checkAmbientInitializer(node); + } + + if ( + isPropertyDeclaration(node) && node.exclamationToken && (!isClassLike(node.parent) || !node.type || node.initializer || + node.flags & NodeFlags.Ambient || isStatic(node) || hasAbstractModifier(node)) + ) { + const message = node.initializer + ? Diagnostics.Declarations_with_initializers_cannot_also_have_definite_assignment_assertions + : !node.type + ? Diagnostics.Declarations_with_definite_assignment_assertions_must_also_have_type_annotations + : Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context; + return grammarErrorOnNode(node.exclamationToken, message); + } + } + + function checkGrammarTopLevelElementForRequiredDeclareModifier(node: Node): boolean { + // A declare modifier is required for any top level .d.ts declaration except export=, export default, export as namespace + // interfaces and imports categories: + // + // DeclarationElement: + // ExportAssignment + // export_opt InterfaceDeclaration + // export_opt TypeAliasDeclaration + // export_opt ImportDeclaration + // export_opt ExternalImportDeclaration + // export_opt AmbientDeclaration + // + // TODO: The spec needs to be amended to reflect this grammar. + if ( + node.kind === SyntaxKind.InterfaceDeclaration || + node.kind === SyntaxKind.TypeAliasDeclaration || + node.kind === SyntaxKind.ImportDeclaration || + node.kind === SyntaxKind.ImportEqualsDeclaration || + node.kind === SyntaxKind.ExportDeclaration || + node.kind === SyntaxKind.ExportAssignment || + node.kind === SyntaxKind.NamespaceExportDeclaration || + hasSyntacticModifier(node, ModifierFlags.Ambient | ModifierFlags.Export | ModifierFlags.Default) + ) { + return false; + } + + return grammarErrorOnFirstToken(node, Diagnostics.Top_level_declarations_in_d_ts_files_must_start_with_either_a_declare_or_export_modifier); + } + + function checkGrammarTopLevelElementsForRequiredDeclareModifier(file: SourceFile): boolean { + for (const decl of file.statements) { + if (isDeclaration(decl) || decl.kind === SyntaxKind.VariableStatement) { + if (checkGrammarTopLevelElementForRequiredDeclareModifier(decl)) { + return true; + } + } + } + return false; + } + + function checkGrammarSourceFile(node: SourceFile): boolean { + return !!(node.flags & NodeFlags.Ambient) && checkGrammarTopLevelElementsForRequiredDeclareModifier(node); + } + + function checkGrammarStatementInAmbientContext(node: Node): boolean { + if (node.flags & NodeFlags.Ambient) { + // Find containing block which is either Block, ModuleBlock, SourceFile + const links = getNodeLinks(node); + if (!links.hasReportedStatementInAmbientContext && (isFunctionLike(node.parent) || isAccessor(node.parent))) { + return getNodeLinks(node).hasReportedStatementInAmbientContext = grammarErrorOnFirstToken(node, Diagnostics.An_implementation_cannot_be_declared_in_ambient_contexts); + } + + // We are either parented by another statement, or some sort of block. + // If we're in a block, we only want to really report an error once + // to prevent noisiness. So use a bit on the block to indicate if + // this has already been reported, and don't report if it has. + // + if (node.parent.kind === SyntaxKind.Block || node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { + const links = getNodeLinks(node.parent); + // Check if the containing block ever report this error + if (!links.hasReportedStatementInAmbientContext) { + return links.hasReportedStatementInAmbientContext = grammarErrorOnFirstToken(node, Diagnostics.Statements_are_not_allowed_in_ambient_contexts); + } + } + else { + // We must be parented by a statement. If so, there's no need + // to report the error as our parent will have already done it. + // Debug.assert(isStatement(node.parent)); + } + } + return false; + } + + function checkGrammarNumericLiteral(node: NumericLiteral) { + // Realism (size) checking + // We should test against `getTextOfNode(node)` rather than `node.text`, because `node.text` for large numeric literals can contain "." + // e.g. `node.text` for numeric literal `1100000000000000000000` is `1.1e21`. + const isFractional = getTextOfNode(node).includes("."); + const isScientific = node.numericLiteralFlags & TokenFlags.Scientific; + + // Scientific notation (e.g. 2e54 and 1e00000000010) can't be converted to bigint + // Fractional numbers (e.g. 9000000000000000.001) are inherently imprecise anyway + if (isFractional || isScientific) { + return; + } + + // Here `node` is guaranteed to be a numeric literal representing an integer. + // We need to judge whether the integer `node` represents is <= 2 ** 53 - 1, which can be accomplished by comparing to `value` defined below because: + // 1) when `node` represents an integer <= 2 ** 53 - 1, `node.text` is its exact string representation and thus `value` precisely represents the integer. + // 2) otherwise, although `node.text` may be imprecise string representation, its mathematical value and consequently `value` cannot be less than 2 ** 53, + // thus the result of the predicate won't be affected. + const value = +node.text; + if (value <= 2 ** 53 - 1) { + return; + } + + addErrorOrSuggestion(/*isError*/ false, createDiagnosticForNode(node, Diagnostics.Numeric_literals_with_absolute_values_equal_to_2_53_or_greater_are_too_large_to_be_represented_accurately_as_integers)); + } + + function checkGrammarBigIntLiteral(node: BigIntLiteral): boolean { + const literalType = isLiteralTypeNode(node.parent) || + isPrefixUnaryExpression(node.parent) && isLiteralTypeNode(node.parent.parent); + if (!literalType) { + if (languageVersion < ScriptTarget.ES2020) { + if (grammarErrorOnNode(node, Diagnostics.BigInt_literals_are_not_available_when_targeting_lower_than_ES2020)) { + return true; + } + } + } + return false; + } + + function grammarErrorAfterFirstToken(node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + const span = getSpanOfTokenAtPosition(sourceFile, node.pos); + diagnostics.add(createFileDiagnostic(sourceFile, textSpanEnd(span), /*length*/ 0, message, ...args)); + return true; + } + return false; + } + + function getAmbientModules(): Symbol[] { + if (!ambientModulesCache) { + ambientModulesCache = []; + globals.forEach((global, sym) => { + // No need to `unescapeLeadingUnderscores`, an escaped symbol is never an ambient module. + if (ambientModuleSymbolRegex.test(sym as string)) { + ambientModulesCache!.push(global); + } + }); + } + return ambientModulesCache; + } + + function checkGrammarImportClause(node: ImportClause): boolean { + if (node.isTypeOnly && node.name && node.namedBindings) { + return grammarErrorOnNode(node, Diagnostics.A_type_only_import_can_specify_a_default_import_or_named_bindings_but_not_both); + } + if (node.isTypeOnly && node.namedBindings?.kind === SyntaxKind.NamedImports) { + return checkGrammarNamedImportsOrExports(node.namedBindings); + } + return false; + } + + function checkGrammarNamedImportsOrExports(namedBindings: NamedImportsOrExports): boolean { + return !!forEach(namedBindings.elements, specifier => { + if (specifier.isTypeOnly) { + return grammarErrorOnFirstToken( + specifier, + specifier.kind === SyntaxKind.ImportSpecifier + ? Diagnostics.The_type_modifier_cannot_be_used_on_a_named_import_when_import_type_is_used_on_its_import_statement + : Diagnostics.The_type_modifier_cannot_be_used_on_a_named_export_when_export_type_is_used_on_its_export_statement, + ); + } + }); + } + + function checkGrammarImportCallExpression(node: ImportCall): boolean { + if (compilerOptions.verbatimModuleSyntax && moduleKind === ModuleKind.CommonJS) { + return grammarErrorOnNode(node, Diagnostics.ESM_syntax_is_not_allowed_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + + if (moduleKind === ModuleKind.ES2015) { + return grammarErrorOnNode(node, Diagnostics.Dynamic_imports_are_only_supported_when_the_module_flag_is_set_to_es2020_es2022_esnext_commonjs_amd_system_umd_node16_or_nodenext); + } + + if (node.typeArguments) { + return grammarErrorOnNode(node, Diagnostics.This_use_of_import_is_invalid_import_calls_can_be_written_but_they_must_have_parentheses_and_cannot_have_type_arguments); + } + + const nodeArguments = node.arguments; + if (moduleKind !== ModuleKind.ESNext && moduleKind !== ModuleKind.NodeNext && moduleKind !== ModuleKind.Node16) { + // We are allowed trailing comma after proposal-import-assertions. + checkGrammarForDisallowedTrailingComma(nodeArguments); + + if (nodeArguments.length > 1) { + const importAttributesArgument = nodeArguments[1]; + return grammarErrorOnNode(importAttributesArgument, Diagnostics.Dynamic_imports_only_support_a_second_argument_when_the_module_option_is_set_to_esnext_node16_or_nodenext); + } + } + + if (nodeArguments.length === 0 || nodeArguments.length > 2) { + return grammarErrorOnNode(node, Diagnostics.Dynamic_imports_can_only_accept_a_module_specifier_and_an_optional_set_of_attributes_as_arguments); + } + + // see: parseArgumentOrArrayLiteralElement...we use this function which parse arguments of callExpression to parse specifier for dynamic import. + // parseArgumentOrArrayLiteralElement allows spread element to be in an argument list which is not allowed as specifier in dynamic import. + const spreadElement = find(nodeArguments, isSpreadElement); + if (spreadElement) { + return grammarErrorOnNode(spreadElement, Diagnostics.Argument_of_dynamic_import_cannot_be_spread_element); + } + return false; + } + + function findMatchingTypeReferenceOrTypeAliasReference(source: Type, unionTarget: UnionOrIntersectionType) { + const sourceObjectFlags = getObjectFlags(source); + if (sourceObjectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous) && unionTarget.flags & TypeFlags.Union) { + return find(unionTarget.types, target => { + if (target.flags & TypeFlags.Object) { + const overlapObjFlags = sourceObjectFlags & getObjectFlags(target); + if (overlapObjFlags & ObjectFlags.Reference) { + return (source as TypeReference).target === (target as TypeReference).target; + } + if (overlapObjFlags & ObjectFlags.Anonymous) { + return !!(source as AnonymousType).aliasSymbol && (source as AnonymousType).aliasSymbol === (target as AnonymousType).aliasSymbol; + } + } + return false; + }); + } + } + + function findBestTypeForObjectLiteral(source: Type, unionTarget: UnionOrIntersectionType) { + if (getObjectFlags(source) & ObjectFlags.ObjectLiteral && someType(unionTarget, isArrayLikeType)) { + return find(unionTarget.types, t => !isArrayLikeType(t)); + } + } + + function findBestTypeForInvokable(source: Type, unionTarget: UnionOrIntersectionType) { + let signatureKind = SignatureKind.Call; + const hasSignatures = getSignaturesOfType(source, signatureKind).length > 0 || + (signatureKind = SignatureKind.Construct, getSignaturesOfType(source, signatureKind).length > 0); + if (hasSignatures) { + return find(unionTarget.types, t => getSignaturesOfType(t, signatureKind).length > 0); + } + } + + function findMostOverlappyType(source: Type, unionTarget: UnionOrIntersectionType) { + let bestMatch: Type | undefined; + if (!(source.flags & (TypeFlags.Primitive | TypeFlags.InstantiablePrimitive))) { + let matchingCount = 0; + for (const target of unionTarget.types) { + if (!(target.flags & (TypeFlags.Primitive | TypeFlags.InstantiablePrimitive))) { + const overlap = getIntersectionType([getIndexType(source), getIndexType(target)]); + if (overlap.flags & TypeFlags.Index) { + // perfect overlap of keys + return target; + } + else if (isUnitType(overlap) || overlap.flags & TypeFlags.Union) { + // We only want to account for literal types otherwise. + // If we have a union of index types, it seems likely that we + // needed to elaborate between two generic mapped types anyway. + const len = overlap.flags & TypeFlags.Union ? countWhere((overlap as UnionType).types, isUnitType) : 1; + if (len >= matchingCount) { + bestMatch = target; + matchingCount = len; + } + } + } + } + } + return bestMatch; + } + + function filterPrimitivesIfContainsNonPrimitive(type: UnionType) { + if (maybeTypeOfKind(type, TypeFlags.NonPrimitive)) { + const result = filterType(type, t => !(t.flags & TypeFlags.Primitive)); + if (!(result.flags & TypeFlags.Never)) { + return result; + } + } + return type; + } + + // Keep this up-to-date with the same logic within `getApparentTypeOfContextualType`, since they should behave similarly + function findMatchingDiscriminantType(source: Type, target: Type, isRelatedTo: (source: Type, target: Type) => Ternary) { + if (target.flags & TypeFlags.Union && source.flags & (TypeFlags.Intersection | TypeFlags.Object)) { + const match = getMatchingUnionConstituentForType(target as UnionType, source); + if (match) { + return match; + } + const sourceProperties = getPropertiesOfType(source); + if (sourceProperties) { + const sourcePropertiesFiltered = findDiscriminantProperties(sourceProperties, target); + if (sourcePropertiesFiltered) { + const discriminated = discriminateTypeByDiscriminableItems(target as UnionType, map(sourcePropertiesFiltered, p => ([() => getTypeOfSymbol(p), p.escapedName] as [() => Type, __String])), isRelatedTo); + if (discriminated !== target) { + return discriminated; + } + } + } + } + return undefined; + } + + function getEffectivePropertyNameForPropertyNameNode(node: PropertyName) { + const name = getPropertyNameForPropertyNameNode(node); + return name ? name : + isComputedPropertyName(node) ? tryGetNameFromType(getTypeOfExpression(node.expression)) : undefined; + } + + function getCombinedModifierFlagsCached(node: Declaration) { + // we hold onto the last node and result to speed up repeated lookups against the same node. + if (lastGetCombinedModifierFlagsNode === node) { + return lastGetCombinedModifierFlagsResult; + } + + lastGetCombinedModifierFlagsNode = node; + lastGetCombinedModifierFlagsResult = getCombinedModifierFlags(node); + return lastGetCombinedModifierFlagsResult; + } + + function getCombinedNodeFlagsCached(node: Node) { + // we hold onto the last node and result to speed up repeated lookups against the same node. + if (lastGetCombinedNodeFlagsNode === node) { + return lastGetCombinedNodeFlagsResult; + } + lastGetCombinedNodeFlagsNode = node; + lastGetCombinedNodeFlagsResult = getCombinedNodeFlags(node); + return lastGetCombinedNodeFlagsResult; + } + + function isVarConstLike(node: VariableDeclaration | VariableDeclarationList) { + const blockScopeKind = getCombinedNodeFlagsCached(node) & NodeFlags.BlockScoped; + return blockScopeKind === NodeFlags.Const || + blockScopeKind === NodeFlags.Using || + blockScopeKind === NodeFlags.AwaitUsing; + } + + function getJSXRuntimeImportSpecifier(file: SourceFile | undefined, specifierText: string) { + // Synthesized JSX import is either first or after tslib + const jsxImportIndex = compilerOptions.importHelpers ? 1 : 0; + const specifier = file?.imports[jsxImportIndex]; + if (specifier) { + Debug.assert(nodeIsSynthesized(specifier) && specifier.text === specifierText, `Expected sourceFile.imports[${jsxImportIndex}] to be the synthesized JSX runtime import`); + } + return specifier; + } + + function getImportHelpersImportSpecifier(file: SourceFile) { + Debug.assert(compilerOptions.importHelpers, "Expected importHelpers to be enabled"); + const specifier = file.imports[0]; + Debug.assert(specifier && nodeIsSynthesized(specifier) && specifier.text === "tslib", `Expected sourceFile.imports[0] to be the synthesized tslib import`); + return specifier; + } +} + +function isNotAccessor(declaration: Declaration): boolean { + // Accessors check for their own matching duplicates, and in contexts where they are valid, there are already duplicate identifier checks + return !isAccessor(declaration); +} + +function isNotOverload(declaration: Declaration): boolean { + return (declaration.kind !== SyntaxKind.FunctionDeclaration && declaration.kind !== SyntaxKind.MethodDeclaration) || + !!(declaration as FunctionDeclaration).body; +} + +/** Like 'isDeclarationName', but returns true for LHS of `import { x as y }` or `export { x as y }`. */ +function isDeclarationNameOrImportPropertyName(name: Node): boolean { + switch (name.parent.kind) { + case SyntaxKind.ImportSpecifier: + case SyntaxKind.ExportSpecifier: + return isIdentifier(name) || name.kind === SyntaxKind.StringLiteral; + default: + return isDeclarationName(name); + } +} + +namespace JsxNames { + export const JSX = "JSX" as __String; + export const IntrinsicElements = "IntrinsicElements" as __String; + export const ElementClass = "ElementClass" as __String; + export const ElementAttributesPropertyNameContainer = "ElementAttributesProperty" as __String; // TODO: Deprecate and remove support + export const ElementChildrenAttributeNameContainer = "ElementChildrenAttribute" as __String; + export const Element = "Element" as __String; + export const ElementType = "ElementType" as __String; + export const IntrinsicAttributes = "IntrinsicAttributes" as __String; + export const IntrinsicClassAttributes = "IntrinsicClassAttributes" as __String; + export const LibraryManagedAttributes = "LibraryManagedAttributes" as __String; +} + +function getIterationTypesKeyFromIterationTypeKind(typeKind: IterationTypeKind) { + switch (typeKind) { + case IterationTypeKind.Yield: + return "yieldType"; + case IterationTypeKind.Return: + return "returnType"; + case IterationTypeKind.Next: + return "nextType"; + } +} + +/** @internal */ +export function signatureHasRestParameter(s: Signature) { + return !!(s.flags & SignatureFlags.HasRestParameter); +} + +/** @internal */ +export function signatureHasLiteralTypes(s: Signature) { + return !!(s.flags & SignatureFlags.HasLiteralTypes); +} + +function createBasicNodeBuilderModuleSpecifierResolutionHost(host: TypeCheckerHost): ModuleSpecifierResolutionHost { + return { + getCommonSourceDirectory: !!(host as Program).getCommonSourceDirectory ? () => (host as Program).getCommonSourceDirectory() : () => "", + getCurrentDirectory: () => host.getCurrentDirectory(), + getSymlinkCache: maybeBind(host, host.getSymlinkCache), + getPackageJsonInfoCache: () => host.getPackageJsonInfoCache?.(), + useCaseSensitiveFileNames: maybeBind(host, host.useCaseSensitiveFileNames), + redirectTargetsMap: host.redirectTargetsMap, + getProjectReferenceRedirect: fileName => host.getProjectReferenceRedirect(fileName), + isSourceOfProjectReferenceRedirect: fileName => host.isSourceOfProjectReferenceRedirect(fileName), + fileExists: fileName => host.fileExists(fileName), + getFileIncludeReasons: () => host.getFileIncludeReasons(), + readFile: host.readFile ? (fileName => host.readFile!(fileName)) : undefined, + }; +} + +interface NodeBuilderContext { + enclosingDeclaration: Node | undefined; + /** + * `enclosingFile` is generated from the initial `enclosingDeclaration` and + * is used to ensure text ranges for generated nodes are not set based on nodes from outside + * the original input's containing file. Checking the `enclosingDeclaration` at the time of + * `setTextRange` is not sufficient, as the `enclosingDeclaration` is modified by the node builder + * as it decends into some types as a shortcut to making certain scopes visible, and may be modified + * into a declaration in a different file from the original input `enclosingDeclaration`! + */ + enclosingFile: SourceFile | undefined; + flags: NodeBuilderFlags; + tracker: SymbolTrackerImpl; + + // State + encounteredError: boolean; + reportedDiagnostic: boolean; + trackedSymbols: TrackedSymbol[] | undefined; + visitedTypes: Set | undefined; + symbolDepth: Map | undefined; + inferTypeParameters: TypeParameter[] | undefined; + approximateLength: number; + truncating: boolean; + mustCreateTypeParameterSymbolList: boolean; + typeParameterSymbolList: Set | undefined; + mustCreateTypeParametersNamesLookups: boolean; + typeParameterNames: Map | undefined; + typeParameterNamesByText: Set | undefined; + typeParameterNamesByTextNextNameCount: Map | undefined; + usedSymbolNames: Set | undefined; + remappedSymbolNames: Map | undefined; + remappedSymbolReferences: Map | undefined; + reverseMappedStack: ReverseMappedSymbol[] | undefined; + bundled: boolean; + mapper: TypeMapper | undefined; +} + +class SymbolTrackerImpl implements SymbolTracker { + moduleResolverHost: ModuleSpecifierResolutionHost & { getCommonSourceDirectory(): string; } | undefined = undefined; + context: NodeBuilderContext; + + readonly inner: SymbolTracker | undefined = undefined; + readonly canTrackSymbol: boolean; + disableTrackSymbol = false; + + constructor(context: NodeBuilderContext, tracker: SymbolTracker | undefined, moduleResolverHost: ModuleSpecifierResolutionHost & { getCommonSourceDirectory(): string; } | undefined) { + while (tracker instanceof SymbolTrackerImpl) { + tracker = tracker.inner; + } + + this.inner = tracker; + this.moduleResolverHost = moduleResolverHost; + this.context = context; + this.canTrackSymbol = !!this.inner?.trackSymbol; + } + + trackSymbol(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags): boolean { + if (this.inner?.trackSymbol && !this.disableTrackSymbol) { + if (this.inner.trackSymbol(symbol, enclosingDeclaration, meaning)) { + this.onDiagnosticReported(); + return true; + } + // Skip recording type parameters as they dont contribute to late painted statements + if (!(symbol.flags & SymbolFlags.TypeParameter)) (this.context.trackedSymbols ??= []).push([symbol, enclosingDeclaration, meaning]); + } + return false; + } + + reportInaccessibleThisError(): void { + if (this.inner?.reportInaccessibleThisError) { + this.onDiagnosticReported(); + this.inner.reportInaccessibleThisError(); + } + } + + reportPrivateInBaseOfClassExpression(propertyName: string): void { + if (this.inner?.reportPrivateInBaseOfClassExpression) { + this.onDiagnosticReported(); + this.inner.reportPrivateInBaseOfClassExpression(propertyName); + } + } + + reportInaccessibleUniqueSymbolError(): void { + if (this.inner?.reportInaccessibleUniqueSymbolError) { + this.onDiagnosticReported(); + this.inner.reportInaccessibleUniqueSymbolError(); + } + } + + reportCyclicStructureError(): void { + if (this.inner?.reportCyclicStructureError) { + this.onDiagnosticReported(); + this.inner.reportCyclicStructureError(); + } + } + + reportLikelyUnsafeImportRequiredError(specifier: string): void { + if (this.inner?.reportLikelyUnsafeImportRequiredError) { + this.onDiagnosticReported(); + this.inner.reportLikelyUnsafeImportRequiredError(specifier); + } + } + + reportTruncationError(): void { + if (this.inner?.reportTruncationError) { + this.onDiagnosticReported(); + this.inner.reportTruncationError(); + } + } + + reportNonlocalAugmentation(containingFile: SourceFile, parentSymbol: Symbol, augmentingSymbol: Symbol): void { + if (this.inner?.reportNonlocalAugmentation) { + this.onDiagnosticReported(); + this.inner.reportNonlocalAugmentation(containingFile, parentSymbol, augmentingSymbol); + } + } + + reportNonSerializableProperty(propertyName: string): void { + if (this.inner?.reportNonSerializableProperty) { + this.onDiagnosticReported(); + this.inner.reportNonSerializableProperty(propertyName); + } + } + + private onDiagnosticReported() { + this.context.reportedDiagnostic = true; + } + + reportInferenceFallback(node: Node): void { + if (this.inner?.reportInferenceFallback) { + this.inner.reportInferenceFallback(node); + } + } +} +import { + __String, + AccessExpression, + AccessFlags, + AccessorDeclaration, + addRange, + addRelatedInfo, + addSyntheticLeadingComment, + AliasDeclarationNode, + AllAccessorDeclarations, + AmbientModuleDeclaration, + and, + AnonymousType, + AnyImportOrJsDocImport, + AnyImportOrReExport, + append, + appendIfUnique, + ArrayBindingPattern, + arrayFrom, + arrayIsHomogeneous, + ArrayLiteralExpression, + arrayOf, + arraysEqual, + arrayToMultiMap, + ArrayTypeNode, + ArrowFunction, + AsExpression, + AssertionExpression, + AssignmentDeclarationKind, + AssignmentKind, + AssignmentPattern, + AwaitExpression, + BaseType, + BigIntLiteral, + BigIntLiteralType, + BinaryExpression, + BinaryOperator, + BinaryOperatorToken, + binarySearch, + BindableObjectDefinePropertyCall, + BindableStaticNameExpression, + BindingElement, + BindingElementGrandparent, + BindingName, + BindingPattern, + bindSourceFile, + Block, + BooleanLiteral, + BreakOrContinueStatement, + CallChain, + CallExpression, + CallLikeExpression, + CallSignatureDeclaration, + CancellationToken, + canHaveDecorators, + canHaveExportModifier, + canHaveFlowNode, + canHaveIllegalDecorators, + canHaveIllegalModifiers, + canHaveJSDoc, + canHaveLocals, + canHaveModifiers, + canHaveSymbol, + canIncludeBindAndCheckDiagnostics, + canUsePropertyAccess, + cartesianProduct, + CaseBlock, + CaseClause, + CaseOrDefaultClause, + cast, + chainDiagnosticMessages, + CharacterCodes, + CheckFlags, + ClassDeclaration, + ClassElement, + classElementOrClassElementParameterIsDecorated, + ClassExpression, + ClassLikeDeclaration, + classOrConstructorParameterIsDecorated, + ClassStaticBlockDeclaration, + clear, + combinePaths, + compareDiagnostics, + comparePaths, + compareValues, + Comparison, + CompilerOptions, + ComputedPropertyName, + concatenate, + concatenateDiagnosticMessageChains, + ConditionalExpression, + ConditionalRoot, + ConditionalType, + ConditionalTypeNode, + ConstructorDeclaration, + ConstructorTypeNode, + ConstructSignatureDeclaration, + contains, + containsParseError, + ContextFlags, + copyEntries, + countWhere, + createBinaryExpressionTrampoline, + createCompilerDiagnostic, + createDetachedDiagnostic, + createDiagnosticCollection, + createDiagnosticForFileFromMessageChain, + createDiagnosticForNode, + createDiagnosticForNodeArray, + createDiagnosticForNodeArrayFromMessageChain, + createDiagnosticForNodeFromMessageChain, + createDiagnosticMessageChainFromDiagnostic, + createEmptyExports, + createEvaluator, + createFileDiagnostic, + createFlowNode, + createGetSymbolWalker, + createModeAwareCacheKey, + createModuleNotFoundChain, + createMultiMap, + createNameResolver, + createPrinterWithDefaults, + createPrinterWithRemoveComments, + createPrinterWithRemoveCommentsNeverAsciiEscape, + createPrinterWithRemoveCommentsOmitTrailingSemicolon, + createPropertyNameNodeForIdentifierOrLiteral, + createScanner, + createSymbolTable, + createSyntacticTypeNodeBuilder, + createTextWriter, + Debug, + Declaration, + DeclarationName, + declarationNameToString, + DeclarationStatement, + DeclarationWithTypeParameterChildren, + DeclarationWithTypeParameters, + Decorator, + deduplicate, + DefaultClause, + defaultMaximumTruncationLength, + DeferredTypeReference, + DeleteExpression, + Diagnostic, + DiagnosticAndArguments, + DiagnosticArguments, + DiagnosticCategory, + DiagnosticMessage, + DiagnosticMessageChain, + DiagnosticRelatedInformation, + Diagnostics, + DiagnosticWithLocation, + DoStatement, + DynamicNamedDeclaration, + ElementAccessChain, + ElementAccessExpression, + ElementFlags, + EmitFlags, + EmitHint, + emitModuleKindIsNonNodeESM, + EmitResolver, + EmitTextWriter, + emptyArray, + endsWith, + EntityName, + EntityNameExpression, + EntityNameOrEntityNameExpression, + entityNameToString, + EnumDeclaration, + EnumMember, + EnumType, + equateValues, + escapeLeadingUnderscores, + escapeString, + EvaluatorResult, + evaluatorResult, + every, + EvolvingArrayType, + ExclamationToken, + ExportAssignment, + exportAssignmentIsAlias, + ExportDeclaration, + ExportSpecifier, + Expression, + expressionResultIsUnused, + ExpressionStatement, + ExpressionWithTypeArguments, + Extension, + ExternalEmitHelpers, + externalHelpersModuleNameText, + factory, + fileExtensionIs, + fileExtensionIsOneOf, + filter, + find, + findAncestor, + findBestPatternMatch, + findConstructorDeclaration, + findIndex, + findLast, + findLastIndex, + findUseStrictPrologue, + first, + firstDefined, + firstIterator, + firstOrUndefined, + firstOrUndefinedIterator, + flatMap, + flatten, + FlowArrayMutation, + FlowAssignment, + FlowCall, + FlowCondition, + FlowFlags, + FlowLabel, + FlowNode, + FlowReduceLabel, + FlowStart, + FlowSwitchClause, + FlowSwitchClauseData, + FlowType, + forEach, + forEachChild, + forEachChildRecursively, + forEachEnclosingBlockScopeContainer, + forEachEntry, + forEachKey, + forEachReturnStatement, + forEachYieldExpression, + ForInOrOfStatement, + ForInStatement, + formatMessage, + ForOfStatement, + ForStatement, + FreshableIntrinsicType, + FreshableType, + FreshObjectLiteralType, + FunctionDeclaration, + FunctionExpression, + FunctionFlags, + FunctionLikeDeclaration, + FunctionOrConstructorTypeNode, + FunctionTypeNode, + GenericType, + GetAccessorDeclaration, + getAliasDeclarationFromName, + getAllJSDocTags, + getAllowSyntheticDefaultImports, + getAncestor, + getAssignedExpandoInitializer, + getAssignmentDeclarationKind, + getAssignmentDeclarationPropertyAccessKind, + getAssignmentTargetKind, + getCanonicalDiagnostic, + getCheckFlags, + getClassExtendsHeritageElement, + getClassLikeDeclarationOfSymbol, + getCombinedLocalAndExportSymbolFlags, + getCombinedModifierFlags, + getCombinedNodeFlags, + getContainingClass, + getContainingClassExcludingClassDecorators, + getContainingClassStaticBlock, + getContainingFunction, + getContainingFunctionOrClassStaticBlock, + getDeclarationModifierFlagsFromSymbol, + getDeclarationOfKind, + getDeclarationsOfKind, + getDeclaredExpandoInitializer, + getDecorators, + getDirectoryPath, + getEffectiveBaseTypeNode, + getEffectiveConstraintOfTypeParameter, + getEffectiveContainerForJSDocTemplateTag, + getEffectiveImplementsTypeNodes, + getEffectiveInitializer, + getEffectiveJSDocHost, + getEffectiveModifierFlags, + getEffectiveReturnTypeNode, + getEffectiveSetAccessorTypeAnnotationNode, + getEffectiveTypeAnnotationNode, + getEffectiveTypeParameterDeclarations, + getElementOrPropertyAccessName, + getEmitDeclarations, + getEmitFlags, + getEmitModuleKind, + getEmitModuleResolutionKind, + getEmitScriptTarget, + getEmitStandardClassFields, + getEnclosingBlockScopeContainer, + getEnclosingContainer, + getEntityNameFromTypeNode, + getErrorSpanForNode, + getEscapedTextOfIdentifierOrLiteral, + getEscapedTextOfJsxAttributeName, + getEscapedTextOfJsxNamespacedName, + getESModuleInterop, + getExpandoInitializer, + getExportAssignmentExpression, + getExternalModuleImportEqualsDeclarationExpression, + getExternalModuleName, + getExternalModuleRequireArgument, + getFirstConstructorWithBody, + getFirstIdentifier, + getFunctionFlags, + getHostSignatureFromJSDoc, + getIdentifierGeneratedImportReference, + getIdentifierTypeArguments, + getImmediatelyInvokedFunctionExpression, + getInitializerOfBinaryExpression, + getInterfaceBaseTypeNodes, + getInvokedExpression, + getIsolatedModules, + getJSDocClassTag, + getJSDocDeprecatedTag, + getJSDocEnumTag, + getJSDocHost, + getJSDocOverloadTags, + getJSDocParameterTags, + getJSDocRoot, + getJSDocSatisfiesExpressionType, + getJSDocTags, + getJSDocThisTag, + getJSDocType, + getJSDocTypeAssertionType, + getJSDocTypeParameterDeclarations, + getJSDocTypeTag, + getJSXImplicitImportBase, + getJSXRuntimeImport, + getJSXTransformEnabled, + getLeftmostAccessExpression, + getLineAndCharacterOfPosition, + getMembersOfDeclaration, + getModifiers, + getModuleInstanceState, + getNameFromImportAttribute, + getNameFromIndexInfo, + getNameOfDeclaration, + getNameOfExpando, + getNamespaceDeclarationNode, + getNewTargetContainer, + getNonAugmentationDeclaration, + getNormalizedAbsolutePath, + getObjectFlags, + getOriginalNode, + getOrUpdate, + getParameterSymbolFromJSDoc, + getParseTreeNode, + getPropertyAssignmentAliasLikeExpression, + getPropertyNameForPropertyNameNode, + getPropertyNameFromType, + getResolutionDiagnostic, + getResolutionModeOverride, + getResolveJsonModule, + getRestParameterElementType, + getRootDeclaration, + getScriptTargetFeatures, + getSelectedEffectiveModifierFlags, + getSemanticJsxChildren, + getSetAccessorValueParameter, + getSingleVariableOfVariableStatement, + getSourceFileOfModule, + getSourceFileOfNode, + getSpanOfTokenAtPosition, + getSpellingSuggestion, + getStrictOptionValue, + getSuperContainer, + getSymbolNameForPrivateIdentifier, + getTextOfIdentifierOrLiteral, + getTextOfJSDocComment, + getTextOfJsxAttributeName, + getTextOfNode, + getTextOfPropertyName, + getThisContainer, + getThisParameter, + getTrailingSemicolonDeferringWriter, + getTypeParameterFromJsDoc, + getUseDefineForClassFields, + group, + hasAbstractModifier, + hasAccessorModifier, + hasAmbientModifier, + hasContextSensitiveParameters, + HasDecorators, + hasDecorators, + hasDynamicName, + hasEffectiveModifier, + hasEffectiveModifiers, + hasEffectiveReadonlyModifier, + HasExpressionInitializer, + hasExtension, + HasIllegalDecorators, + HasIllegalModifiers, + hasInferredType, + HasInitializer, + hasInitializer, + hasJSDocNodes, + hasJSDocParameterTags, + hasJsonModuleEmitEnabled, + HasLocals, + HasModifiers, + hasOnlyExpressionInitializer, + hasOverrideModifier, + hasPossibleExternalModuleReference, + hasQuestionToken, + hasResolutionModeOverride, + hasRestParameter, + hasScopeMarker, + hasStaticModifier, + hasSyntacticModifier, + hasSyntacticModifiers, + hasType, + HeritageClause, + Identifier, + identifierToKeywordKind, + IdentifierTypePredicate, + idText, + IfStatement, + ImportAttribute, + ImportAttributes, + ImportCall, + ImportClause, + ImportDeclaration, + ImportEqualsDeclaration, + ImportOrExportSpecifier, + ImportSpecifier, + ImportTypeNode, + IndexedAccessType, + IndexedAccessTypeNode, + IndexFlags, + IndexInfo, + IndexKind, + indexOfNode, + IndexSignatureDeclaration, + IndexType, + indicesOf, + InferenceContext, + InferenceFlags, + InferenceInfo, + InferencePriority, + InferTypeNode, + InstanceofExpression, + InstantiableType, + InstantiationExpressionType, + InterfaceDeclaration, + InterfaceType, + InterfaceTypeWithDeclaredMembers, + InternalSymbolName, + IntersectionFlags, + IntersectionType, + IntersectionTypeNode, + intrinsicTagNameToString, + IntrinsicType, + introducesArgumentsExoticObject, + isAccessExpression, + isAccessor, + isAliasableExpression, + isAmbientModule, + isArray, + isArrayBindingPattern, + isArrayLiteralExpression, + isArrowFunction, + isAssertionExpression, + isAssignmentDeclaration, + isAssignmentExpression, + isAssignmentOperator, + isAssignmentPattern, + isAssignmentTarget, + isAutoAccessorPropertyDeclaration, + isAwaitExpression, + isBinaryExpression, + isBindableObjectDefinePropertyCall, + isBindableStaticElementAccessExpression, + isBindableStaticNameExpression, + isBindingElement, + isBindingElementOfBareOrAccessedRequire, + isBindingPattern, + isBlock, + isBlockOrCatchScoped, + isBlockScopedContainerTopLevel, + isBooleanLiteral, + isCallChain, + isCallExpression, + isCallLikeExpression, + isCallLikeOrFunctionLikeExpression, + isCallOrNewExpression, + isCallSignatureDeclaration, + isCatchClause, + isCatchClauseVariableDeclaration, + isCatchClauseVariableDeclarationOrBindingElement, + isCheckJsEnabledForFile, + isClassDeclaration, + isClassElement, + isClassExpression, + isClassInstanceProperty, + isClassLike, + isClassStaticBlockDeclaration, + isCommaSequence, + isCommonJsExportedExpression, + isCommonJsExportPropertyAssignment, + isCompoundAssignment, + isComputedNonLiteralName, + isComputedPropertyName, + isConditionalTypeNode, + isConstAssertion, + isConstructorDeclaration, + isConstructorTypeNode, + isConstructSignatureDeclaration, + isConstTypeReference, + isDeclaration, + isDeclarationFileName, + isDeclarationName, + isDeclarationReadonly, + isDecorator, + isDefaultedExpandoInitializer, + isDeleteTarget, + isDottedName, + isDynamicName, + isEffectiveExternalModule, + isElementAccessExpression, + isEntityName, + isEntityNameExpression, + isEnumConst, + isEnumDeclaration, + isEnumMember, + isExclusivelyTypeOnlyImportOrExport, + isExpandoPropertyDeclaration, + isExportAssignment, + isExportDeclaration, + isExportsIdentifier, + isExportSpecifier, + isExpression, + isExpressionNode, + isExpressionOfOptionalChainRoot, + isExpressionStatement, + isExpressionWithTypeArguments, + isExpressionWithTypeArgumentsInClassExtendsClause, + isExternalModule, + isExternalModuleAugmentation, + isExternalModuleImportEqualsDeclaration, + isExternalModuleIndicator, + isExternalModuleNameRelative, + isExternalModuleReference, + isExternalModuleSymbol, + isExternalOrCommonJsModule, + isForInOrOfStatement, + isForInStatement, + isForOfStatement, + isForStatement, + isFunctionDeclaration, + isFunctionExpression, + isFunctionExpressionOrArrowFunction, + isFunctionLike, + isFunctionLikeDeclaration, + isFunctionLikeOrClassStaticBlockDeclaration, + isFunctionOrModuleBlock, + isFunctionTypeNode, + isGeneratedIdentifier, + isGetAccessor, + isGetAccessorDeclaration, + isGetOrSetAccessorDeclaration, + isGlobalScopeAugmentation, + isGlobalSourceFile, + isHeritageClause, + isIdentifier, + isIdentifierText, + isIdentifierTypePredicate, + isIdentifierTypeReference, + isIfStatement, + isImportAttributes, + isImportCall, + isImportClause, + isImportDeclaration, + isImportEqualsDeclaration, + isImportKeyword, + isImportOrExportSpecifier, + isImportSpecifier, + isImportTypeNode, + isInCompoundLikeAssignment, + isIndexedAccessTypeNode, + isInExpressionContext, + isInfinityOrNaNString, + isInitializedProperty, + isInJSDoc, + isInJSFile, + isInJsonFile, + isInstanceOfExpression, + isInterfaceDeclaration, + isInternalModuleImportEqualsDeclaration, + isInTopLevelContext, + isIntrinsicJsxName, + isInTypeQuery, + isIterationStatement, + isJSDocAllType, + isJSDocAugmentsTag, + isJSDocCallbackTag, + isJSDocConstructSignature, + isJSDocFunctionType, + isJSDocImportTag, + isJSDocIndexSignature, + isJSDocLinkLike, + isJSDocMemberName, + isJSDocNameReference, + isJSDocNode, + isJSDocNonNullableType, + isJSDocNullableType, + isJSDocOptionalParameter, + isJSDocOptionalType, + isJSDocOverloadTag, + isJSDocParameterTag, + isJSDocPropertyLikeTag, + isJSDocPropertyTag, + isJSDocSatisfiesExpression, + isJSDocSatisfiesTag, + isJSDocSignature, + isJSDocTemplateTag, + isJSDocThisTag, + isJSDocTypeAlias, + isJSDocTypeAssertion, + isJSDocTypedefTag, + isJSDocTypeExpression, + isJSDocTypeLiteral, + isJSDocUnknownType, + isJSDocVariadicType, + isJsonSourceFile, + isJsxAttribute, + isJsxAttributeLike, + isJsxAttributes, + isJsxElement, + isJsxNamespacedName, + isJsxOpeningElement, + isJsxOpeningFragment, + isJsxOpeningLikeElement, + isJsxSelfClosingElement, + isJsxSpreadAttribute, + isJSXTagName, + isKnownSymbol, + isLateVisibilityPaintedStatement, + isLeftHandSideExpression, + isLineBreak, + isLiteralComputedPropertyDeclarationName, + isLiteralExpression, + isLiteralExpressionOfObject, + isLiteralImportTypeNode, + isLiteralTypeNode, + isLogicalOrCoalescingBinaryExpression, + isLogicalOrCoalescingBinaryOperator, + isMappedTypeNode, + isMetaProperty, + isMethodDeclaration, + isMethodSignature, + isModifier, + isModuleBlock, + isModuleDeclaration, + isModuleExportsAccessExpression, + isModuleIdentifier, + isModuleOrEnumDeclaration, + isModuleWithStringLiteralName, + isNamedDeclaration, + isNamedEvaluationSource, + isNamedExports, + isNamedTupleMember, + isNamespaceExport, + isNamespaceExportDeclaration, + isNamespaceReexportDeclaration, + isNewExpression, + isNodeDescendantOf, + isNonNullAccess, + isNonNullExpression, + isNumericLiteral, + isNumericLiteralName, + isObjectBindingPattern, + isObjectLiteralElementLike, + isObjectLiteralExpression, + isObjectLiteralMethod, + isObjectLiteralOrClassExpressionMethodOrAccessor, + isOmittedExpression, + isOptionalChain, + isOptionalChainRoot, + isOptionalDeclaration, + isOptionalJSDocPropertyLikeTag, + isOptionalTypeNode, + isOutermostOptionalChain, + isParameter, + isParameterPropertyDeclaration, + isParenthesizedExpression, + isParenthesizedTypeNode, + isPartOfParameterDeclaration, + isPartOfTypeNode, + isPartOfTypeQuery, + isPlainJsFile, + isPrefixUnaryExpression, + isPrivateIdentifier, + isPrivateIdentifierClassElementDeclaration, + isPrivateIdentifierPropertyAccessExpression, + isPropertyAccessEntityNameExpression, + isPropertyAccessExpression, + isPropertyAccessOrQualifiedName, + isPropertyAccessOrQualifiedNameOrImportTypeNode, + isPropertyAssignment, + isPropertyDeclaration, + isPropertyName, + isPropertyNameLiteral, + isPropertySignature, + isPrototypeAccess, + isPrototypePropertyAssignment, + isPushOrUnshiftIdentifier, + isQualifiedName, + isRequireCall, + isRestParameter, + isRestTypeNode, + isRightSideOfAccessExpression, + isRightSideOfInstanceofExpression, + isRightSideOfQualifiedNameOrPropertyAccess, + isRightSideOfQualifiedNameOrPropertyAccessOrJSDocMemberName, + isSameEntityName, + isSatisfiesExpression, + isSetAccessor, + isSetAccessorDeclaration, + isShorthandAmbientModuleSymbol, + isShorthandPropertyAssignment, + isSingleOrDoubleQuote, + isSourceFile, + isSourceFileJS, + isSpreadAssignment, + isSpreadElement, + isStatement, + isStatementWithLocals, + isStatic, + isString, + isStringANonContextualKeyword, + isStringLiteral, + isStringLiteralLike, + isStringOrNumericLiteralLike, + isSuperCall, + isSuperProperty, + isTaggedTemplateExpression, + isTemplateSpan, + isThisContainerOrFunctionBlock, + isThisIdentifier, + isThisInitializedDeclaration, + isThisInitializedObjectBindingExpression, + isThisInTypeQuery, + isThisProperty, + isThisTypeNode, + isThisTypeParameter, + isThisTypePredicate, + isTransientSymbol, + isTupleTypeNode, + isTypeAlias, + isTypeAliasDeclaration, + isTypeDeclaration, + isTypeLiteralNode, + isTypeNode, + isTypeNodeKind, + isTypeOfExpression, + isTypeOnlyImportDeclaration, + isTypeOnlyImportOrExportDeclaration, + isTypeOperatorNode, + isTypeParameterDeclaration, + isTypePredicateNode, + isTypeQueryNode, + isTypeReferenceNode, + isTypeReferenceType, + isTypeUsableAsPropertyName, + isUMDExportSymbol, + isValidBigIntString, + isValidESSymbolDeclaration, + isValidTypeOnlyAliasUseSite, + isValueSignatureDeclaration, + isVariableDeclaration, + isVariableDeclarationInitializedToBareOrAccessedRequire, + isVariableDeclarationInVariableStatement, + isVariableDeclarationList, + isVariableLike, + isVariableLikeOrAccessor, + isVariableStatement, + isWriteAccess, + isWriteOnlyAccess, + IterableOrIteratorType, + IterationTypes, + JSDoc, + JSDocAugmentsTag, + JSDocCallbackTag, + JSDocComment, + JSDocFunctionType, + JSDocImplementsTag, + JSDocImportTag, + JSDocLink, + JSDocLinkCode, + JSDocLinkPlain, + JSDocMemberName, + JSDocNullableType, + JSDocOptionalType, + JSDocOverloadTag, + JSDocParameterTag, + JSDocPrivateTag, + JSDocPropertyLikeTag, + JSDocPropertyTag, + JSDocProtectedTag, + JSDocPublicTag, + JSDocSatisfiesTag, + JSDocSignature, + JSDocTemplateTag, + JSDocThisTag, + JSDocTypeAssertion, + JSDocTypedefTag, + JSDocTypeExpression, + JSDocTypeLiteral, + JSDocTypeReferencingNode, + JSDocTypeTag, + JSDocVariadicType, + JsxAttribute, + JsxAttributeLike, + JsxAttributeName, + JsxAttributes, + JsxAttributeValue, + JsxChild, + JsxClosingElement, + JsxElement, + JsxEmit, + JsxExpression, + JsxFlags, + JsxFragment, + JsxNamespacedName, + JsxOpeningElement, + JsxOpeningFragment, + JsxOpeningLikeElement, + JsxReferenceKind, + JsxSelfClosingElement, + JsxSpreadAttribute, + JsxTagNameExpression, + KeywordTypeNode, + LabeledStatement, + LanguageFeatureMinimumTarget, + last, + lastOrUndefined, + LateBoundBinaryExpressionDeclaration, + LateBoundDeclaration, + LateBoundName, + LateVisibilityPaintedStatement, + LazyNodeCheckFlags, + length, + LiteralExpression, + LiteralType, + LiteralTypeNode, + map, + mapDefined, + MappedSymbol, + MappedType, + MappedTypeNode, + MatchingKeys, + maybeBind, + MemberOverrideStatus, + MetaProperty, + MethodDeclaration, + MethodSignature, + minAndMax, + MinusToken, + Modifier, + ModifierFlags, + modifiersToFlags, + modifierToFlag, + ModuleBlock, + ModuleDeclaration, + ModuleExportName, + moduleExportNameIsDefault, + moduleExportNameTextEscaped, + moduleExportNameTextUnescaped, + ModuleInstanceState, + ModuleKind, + ModuleResolutionKind, + ModuleSpecifierResolutionHost, + Mutable, + NamedDeclaration, + NamedExports, + NamedImportsOrExports, + NamedTupleMember, + NamespaceDeclaration, + NamespaceExport, + NamespaceExportDeclaration, + NamespaceImport, + needsScopeMarker, + NewExpression, + Node, + NodeArray, + NodeBuilderFlags, + nodeCanBeDecorated, + NodeCheckFlags, + NodeFlags, + nodeHasName, + nodeIsMissing, + nodeIsPresent, + nodeIsSynthesized, + NodeLinks, + nodeStartsNewLexicalEnvironment, + NodeWithTypeArguments, + NonNullChain, + NonNullExpression, + not, + noTruncationMaximumTruncationLength, + NumberLiteralType, + NumericLiteral, + objectAllocator, + ObjectBindingPattern, + ObjectFlags, + ObjectFlagsType, + ObjectLiteralElementLike, + ObjectLiteralExpression, + ObjectType, + OptionalChain, + OptionalTypeNode, + or, + orderedRemoveItemAt, + OuterExpressionKinds, + ParameterDeclaration, + parameterIsThisKeyword, + ParameterPropertyDeclaration, + ParenthesizedExpression, + ParenthesizedTypeNode, + parseIsolatedEntityName, + parseNodeFactory, + parsePseudoBigInt, + parseValidBigInt, + Path, + pathIsRelative, + PatternAmbientModule, + PlusToken, + PostfixUnaryExpression, + PrefixUnaryExpression, + PrivateIdentifier, + Program, + PromiseOrAwaitableType, + PropertyAccessChain, + PropertyAccessEntityNameExpression, + PropertyAccessExpression, + PropertyAssignment, + PropertyDeclaration, + PropertyName, + PropertySignature, + PseudoBigInt, + pseudoBigIntToString, + PunctuationSyntaxKind, + pushIfUnique, + QualifiedName, + QuestionToken, + rangeEquals, + rangeOfNode, + rangeOfTypeParameters, + ReadonlyKeyword, + reduceLeft, + RegularExpressionLiteral, + RelationComparisonResult, + relativeComplement, + removeExtension, + removePrefix, + replaceElement, + resolutionExtensionIsTSOrJson, + ResolutionMode, + ResolvedModuleFull, + ResolvedType, + resolvingEmptyArray, + RestTypeNode, + ReturnStatement, + ReverseMappedSymbol, + ReverseMappedType, + sameMap, + SatisfiesExpression, + Scanner, + scanTokenAtPosition, + ScriptKind, + ScriptTarget, + SetAccessorDeclaration, + setCommentRange as setCommentRangeWorker, + setEmitFlags, + setIdentifierTypeArguments, + setNodeFlags, + setOriginalNode, + setParent, + setSyntheticLeadingComments, + setTextRange as setTextRangeWorker, + setTextRangePosEnd, + setValueDeclaration, + ShorthandPropertyAssignment, + shouldAllowImportingTsExtension, + shouldPreserveConstEnums, + Signature, + SignatureDeclaration, + SignatureFlags, + SignatureKind, + singleElementArray, + SingleSignatureType, + skipOuterExpressions, + skipParentheses, + skipTrivia, + skipTypeChecking, + skipTypeParentheses, + some, + SourceFile, + SpreadAssignment, + SpreadElement, + startsWith, + Statement, + StringLiteral, + StringLiteralLike, + StringLiteralType, + StringMappingType, + stripQuotes, + StructuredType, + SubstitutionType, + SuperCall, + SwitchStatement, + Symbol, + SymbolAccessibility, + SymbolAccessibilityResult, + SymbolFlags, + SymbolFormatFlags, + SymbolId, + SymbolLinks, + symbolName, + SymbolTable, + SymbolTracker, + SymbolVisibilityResult, + SyntaxKind, + SyntheticDefaultModuleType, + SyntheticExpression, + TaggedTemplateExpression, + TemplateExpression, + TemplateLiteralType, + TemplateLiteralTypeNode, + Ternary, + textRangeContainsPositionInclusive, + TextSpan, + textSpanContainsPosition, + textSpanEnd, + ThisExpression, + ThisTypeNode, + ThrowStatement, + TokenFlags, + tokenToString, + tracing, + TracingNode, + TrackedSymbol, + TransientSymbol, + TransientSymbolLinks, + tryAddToSet, + tryCast, + tryExtractTSExtension, + tryGetClassImplementingOrExtendingExpressionWithTypeArguments, + tryGetExtensionFromPath, + tryGetJSDocSatisfiesTypeNode, + tryGetModuleSpecifierFromDeclaration, + tryGetPropertyAccessOrIdentifierToString, + TryStatement, + TupleType, + TupleTypeNode, + TupleTypeReference, + Type, + TypeAliasDeclaration, + TypeAssertion, + TypeChecker, + TypeCheckerHost, + TypeComparer, + TypeElement, + TypeFlags, + TypeFormatFlags, + TypeId, + TypeLiteralNode, + TypeMapKind, + TypeMapper, + TypeNode, + TypeNodeSyntaxKind, + TypeOfExpression, + TypeOnlyAliasDeclaration, + TypeOnlyCompatibleAliasDeclaration, + TypeOperatorNode, + TypeParameter, + TypeParameterDeclaration, + TypePredicate, + TypePredicateKind, + TypePredicateNode, + TypeQueryNode, + TypeReference, + TypeReferenceNode, + TypeReferenceSerializationKind, + TypeReferenceType, + TypeVariable, + unescapeLeadingUnderscores, + UnionOrIntersectionType, + UnionOrIntersectionTypeNode, + UnionReduction, + UnionType, + UnionTypeNode, + UniqueESSymbolType, + usingSingleLineStringWriter, + VariableDeclaration, + VariableDeclarationList, + VariableLikeDeclaration, + VariableStatement, + VarianceFlags, + visitEachChild as visitEachChildWorker, + visitNode, + visitNodes, + Visitor, + VisitResult, + VoidExpression, + walkUpBindingElementsAndPatterns, + walkUpOuterExpressions, + walkUpParenthesizedExpressions, + walkUpParenthesizedTypes, + walkUpParenthesizedTypesAndGetParentAndChild, + WhileStatement, + WideningContext, + WithStatement, + YieldExpression, +} from "./_namespaces/ts.js"; +import * as moduleSpecifiers from "./_namespaces/ts.moduleSpecifiers.js"; +import * as performance from "./_namespaces/ts.performance.js"; + +const ambientModuleSymbolRegex = /^".+"$/; +const anon = "(anonymous)" as __String & string; + +const enum ReferenceHint { + Unspecified, + Identifier, + Property, + ExportAssignment, + Jsx, + AsyncFunction, + ExportImportEquals, + ExportSpecifier, + Decorator, +} + +let nextSymbolId = 1; +let nextNodeId = 1; +let nextMergeId = 1; +let nextFlowId = 1; + +const enum IterationUse { + AllowsSyncIterablesFlag = 1 << 0, + AllowsAsyncIterablesFlag = 1 << 1, + AllowsStringInputFlag = 1 << 2, + ForOfFlag = 1 << 3, + YieldStarFlag = 1 << 4, + SpreadFlag = 1 << 5, + DestructuringFlag = 1 << 6, + PossiblyOutOfBounds = 1 << 7, + + // Spread, Destructuring, Array element assignment + Element = AllowsSyncIterablesFlag, + Spread = AllowsSyncIterablesFlag | SpreadFlag, + Destructuring = AllowsSyncIterablesFlag | DestructuringFlag, + + ForOf = AllowsSyncIterablesFlag | AllowsStringInputFlag | ForOfFlag, + ForAwaitOf = AllowsSyncIterablesFlag | AllowsAsyncIterablesFlag | AllowsStringInputFlag | ForOfFlag, + + YieldStar = AllowsSyncIterablesFlag | YieldStarFlag, + AsyncYieldStar = AllowsSyncIterablesFlag | AllowsAsyncIterablesFlag | YieldStarFlag, + + GeneratorReturnType = AllowsSyncIterablesFlag, + AsyncGeneratorReturnType = AllowsAsyncIterablesFlag, +} + +const enum IterationTypeKind { + Yield, + Return, + Next, +} + +interface IterationTypesResolver { + iterableCacheKey: "iterationTypesOfAsyncIterable" | "iterationTypesOfIterable"; + iteratorCacheKey: "iterationTypesOfAsyncIterator" | "iterationTypesOfIterator"; + iteratorSymbolName: "asyncIterator" | "iterator"; + getGlobalIteratorType: (reportErrors: boolean) => GenericType; + getGlobalIterableType: (reportErrors: boolean) => GenericType; + getGlobalIterableIteratorType: (reportErrors: boolean) => GenericType; + getGlobalGeneratorType: (reportErrors: boolean) => GenericType; + resolveIterationType: (type: Type, errorNode: Node | undefined) => Type | undefined; + mustHaveANextMethodDiagnostic: DiagnosticMessage; + mustBeAMethodDiagnostic: DiagnosticMessage; + mustHaveAValueDiagnostic: DiagnosticMessage; +} + +const enum WideningKind { + Normal, + FunctionReturn, + GeneratorNext, + GeneratorYield, +} + +// dprint-ignore +/** @internal */ +export const enum TypeFacts { + None = 0, + TypeofEQString = 1 << 0, // typeof x === "string" + TypeofEQNumber = 1 << 1, // typeof x === "number" + TypeofEQBigInt = 1 << 2, // typeof x === "bigint" + TypeofEQBoolean = 1 << 3, // typeof x === "boolean" + TypeofEQSymbol = 1 << 4, // typeof x === "symbol" + TypeofEQObject = 1 << 5, // typeof x === "object" + TypeofEQFunction = 1 << 6, // typeof x === "function" + TypeofEQHostObject = 1 << 7, // typeof x === "xxx" + TypeofNEString = 1 << 8, // typeof x !== "string" + TypeofNENumber = 1 << 9, // typeof x !== "number" + TypeofNEBigInt = 1 << 10, // typeof x !== "bigint" + TypeofNEBoolean = 1 << 11, // typeof x !== "boolean" + TypeofNESymbol = 1 << 12, // typeof x !== "symbol" + TypeofNEObject = 1 << 13, // typeof x !== "object" + TypeofNEFunction = 1 << 14, // typeof x !== "function" + TypeofNEHostObject = 1 << 15, // typeof x !== "xxx" + EQUndefined = 1 << 16, // x === undefined + EQNull = 1 << 17, // x === null + EQUndefinedOrNull = 1 << 18, // x === undefined / x === null + NEUndefined = 1 << 19, // x !== undefined + NENull = 1 << 20, // x !== null + NEUndefinedOrNull = 1 << 21, // x != undefined / x != null + Truthy = 1 << 22, // x + Falsy = 1 << 23, // !x + IsUndefined = 1 << 24, // Contains undefined or intersection with undefined + IsNull = 1 << 25, // Contains null or intersection with null + IsUndefinedOrNull = IsUndefined | IsNull, + All = (1 << 27) - 1, + // The following members encode facts about particular kinds of types for use in the getTypeFacts function. + // The presence of a particular fact means that the given test is true for some (and possibly all) values + // of that kind of type. + BaseStringStrictFacts = TypeofEQString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseStringFacts = BaseStringStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + StringStrictFacts = BaseStringStrictFacts | Truthy | Falsy, + StringFacts = BaseStringFacts | Truthy, + EmptyStringStrictFacts = BaseStringStrictFacts | Falsy, + EmptyStringFacts = BaseStringFacts, + NonEmptyStringStrictFacts = BaseStringStrictFacts | Truthy, + NonEmptyStringFacts = BaseStringFacts | Truthy, + BaseNumberStrictFacts = TypeofEQNumber | TypeofNEString | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseNumberFacts = BaseNumberStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + NumberStrictFacts = BaseNumberStrictFacts | Truthy | Falsy, + NumberFacts = BaseNumberFacts | Truthy, + ZeroNumberStrictFacts = BaseNumberStrictFacts | Falsy, + ZeroNumberFacts = BaseNumberFacts, + NonZeroNumberStrictFacts = BaseNumberStrictFacts | Truthy, + NonZeroNumberFacts = BaseNumberFacts | Truthy, + BaseBigIntStrictFacts = TypeofEQBigInt | TypeofNEString | TypeofNENumber | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseBigIntFacts = BaseBigIntStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + BigIntStrictFacts = BaseBigIntStrictFacts | Truthy | Falsy, + BigIntFacts = BaseBigIntFacts | Truthy, + ZeroBigIntStrictFacts = BaseBigIntStrictFacts | Falsy, + ZeroBigIntFacts = BaseBigIntFacts, + NonZeroBigIntStrictFacts = BaseBigIntStrictFacts | Truthy, + NonZeroBigIntFacts = BaseBigIntFacts | Truthy, + BaseBooleanStrictFacts = TypeofEQBoolean | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseBooleanFacts = BaseBooleanStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + BooleanStrictFacts = BaseBooleanStrictFacts | Truthy | Falsy, + BooleanFacts = BaseBooleanFacts | Truthy, + FalseStrictFacts = BaseBooleanStrictFacts | Falsy, + FalseFacts = BaseBooleanFacts, + TrueStrictFacts = BaseBooleanStrictFacts | Truthy, + TrueFacts = BaseBooleanFacts | Truthy, + SymbolStrictFacts = TypeofEQSymbol | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull | Truthy, + SymbolFacts = SymbolStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + ObjectStrictFacts = TypeofEQObject | TypeofEQHostObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEFunction | NEUndefined | NENull | NEUndefinedOrNull | Truthy, + ObjectFacts = ObjectStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + FunctionStrictFacts = TypeofEQFunction | TypeofEQHostObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | NEUndefined | NENull | NEUndefinedOrNull | Truthy, + FunctionFacts = FunctionStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + VoidFacts = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | EQUndefined | EQUndefinedOrNull | NENull | Falsy, + UndefinedFacts = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | EQUndefined | EQUndefinedOrNull | NENull | Falsy | IsUndefined, + NullFacts = TypeofEQObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEFunction | TypeofNEHostObject | EQNull | EQUndefinedOrNull | NEUndefined | Falsy | IsNull, + EmptyObjectStrictFacts = All & ~(EQUndefined | EQNull | EQUndefinedOrNull | IsUndefinedOrNull), + EmptyObjectFacts = All & ~IsUndefinedOrNull, + UnknownFacts = All & ~IsUndefinedOrNull, + AllTypeofNE = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | NEUndefined, + // Masks + OrFactsMask = TypeofEQFunction | TypeofNEObject, + AndFactsMask = All & ~OrFactsMask, +} + +const typeofNEFacts: ReadonlyMap = new Map(Object.entries({ + string: TypeFacts.TypeofNEString, + number: TypeFacts.TypeofNENumber, + bigint: TypeFacts.TypeofNEBigInt, + boolean: TypeFacts.TypeofNEBoolean, + symbol: TypeFacts.TypeofNESymbol, + undefined: TypeFacts.NEUndefined, + object: TypeFacts.TypeofNEObject, + function: TypeFacts.TypeofNEFunction, +})); + +type TypeSystemEntity = Node | Symbol | Type | Signature; + +const enum TypeSystemPropertyName { + Type, + ResolvedBaseConstructorType, + DeclaredType, + ResolvedReturnType, + ImmediateBaseConstraint, + ResolvedTypeArguments, + ResolvedBaseTypes, + WriteType, + ParameterInitializerContainsUndefined, +} + +// dprint-ignore +/** @internal */ +export const enum CheckMode { + Normal = 0, // Normal type checking + Contextual = 1 << 0, // Explicitly assigned contextual type, therefore not cacheable + Inferential = 1 << 1, // Inferential typing + SkipContextSensitive = 1 << 2, // Skip context sensitive function expressions + SkipGenericFunctions = 1 << 3, // Skip single signature generic functions + IsForSignatureHelp = 1 << 4, // Call resolution for purposes of signature help + RestBindingElement = 1 << 5, // Checking a type that is going to be used to determine the type of a rest binding element + // e.g. in `const { a, ...rest } = foo`, when checking the type of `foo` to determine the type of `rest`, + // we need to preserve generic types instead of substituting them for constraints + TypeOnly = 1 << 6, // Called from getTypeOfExpression, diagnostics may be omitted +} + +/** @internal */ +export const enum SignatureCheckMode { + None = 0, + BivariantCallback = 1 << 0, + StrictCallback = 1 << 1, + IgnoreReturnTypes = 1 << 2, + StrictArity = 1 << 3, + StrictTopSignature = 1 << 4, + Callback = BivariantCallback | StrictCallback, +} + +const enum IntersectionState { + None = 0, + Source = 1 << 0, // Source type is a constituent of an outer intersection + Target = 1 << 1, // Target type is a constituent of an outer intersection +} + +const enum RecursionFlags { + None = 0, + Source = 1 << 0, + Target = 1 << 1, + Both = Source | Target, +} + +const enum MappedTypeModifiers { + IncludeReadonly = 1 << 0, + ExcludeReadonly = 1 << 1, + IncludeOptional = 1 << 2, + ExcludeOptional = 1 << 3, +} + +const enum MappedTypeNameTypeKind { + None, + Filtering, + Remapping, +} + +const enum ExpandingFlags { + None = 0, + Source = 1, + Target = 1 << 1, + Both = Source | Target, +} + +const enum MembersOrExportsResolutionKind { + resolvedExports = "resolvedExports", + resolvedMembers = "resolvedMembers", +} + +const enum UnusedKind { + Local, + Parameter, +} + +/** @param containingNode Node to check for parse error */ +type AddUnusedDiagnostic = (containingNode: Node, type: UnusedKind, diagnostic: DiagnosticWithLocation) => void; + +const isNotOverloadAndNotAccessor = and(isNotOverload, isNotAccessor); + +const enum DeclarationMeaning { + GetAccessor = 1, + SetAccessor = 2, + PropertyAssignment = 4, + Method = 8, + PrivateStatic = 16, + GetOrSetAccessor = GetAccessor | SetAccessor, + PropertyAssignmentOrMethod = PropertyAssignment | Method, +} + +const enum DeclarationSpaces { + None = 0, + ExportValue = 1 << 0, + ExportType = 1 << 1, + ExportNamespace = 1 << 2, +} + +const enum MinArgumentCountFlags { + None = 0, + StrongArityForUntypedJS = 1 << 0, + VoidIsNonOptional = 1 << 1, +} + +const enum IntrinsicTypeKind { + Uppercase, + Lowercase, + Capitalize, + Uncapitalize, + NoInfer, +} + +const intrinsicTypeKinds: ReadonlyMap = new Map(Object.entries({ + Uppercase: IntrinsicTypeKind.Uppercase, + Lowercase: IntrinsicTypeKind.Lowercase, + Capitalize: IntrinsicTypeKind.Capitalize, + Uncapitalize: IntrinsicTypeKind.Uncapitalize, + NoInfer: IntrinsicTypeKind.NoInfer, +})); + +const SymbolLinks = class implements SymbolLinks { + declare _symbolLinksBrand: any; +}; + +function NodeLinks(this: NodeLinks) { + this.flags = NodeCheckFlags.None; +} + +/** @internal */ +export function getNodeId(node: Node): number { + if (!node.id) { + node.id = nextNodeId; + nextNodeId++; + } + return node.id; +} + +/** @internal */ +export function getSymbolId(symbol: Symbol): SymbolId { + if (!symbol.id) { + symbol.id = nextSymbolId; + nextSymbolId++; + } + + return symbol.id; +} + +/** @internal */ +export function isInstantiatedModule(node: ModuleDeclaration, preserveConstEnums: boolean) { + const moduleState = getModuleInstanceState(node); + return moduleState === ModuleInstanceState.Instantiated || + (preserveConstEnums && moduleState === ModuleInstanceState.ConstEnumOnly); +} + +/** @internal */ +export function createTypeChecker(host: TypeCheckerHost): TypeChecker { + // Why var? It avoids TDZ checks in the runtime which can be costly. + // See: https://github.com/microsoft/TypeScript/issues/52924 + /* eslint-disable no-var */ + var deferredDiagnosticsCallbacks: (() => void)[] = []; + + var addLazyDiagnostic = (arg: () => void) => { + deferredDiagnosticsCallbacks.push(arg); + }; + + // Cancellation that controls whether or not we can cancel in the middle of type checking. + // In general cancelling is *not* safe for the type checker. We might be in the middle of + // computing something, and we will leave our internals in an inconsistent state. Callers + // who set the cancellation token should catch if a cancellation exception occurs, and + // should throw away and create a new TypeChecker. + // + // Currently we only support setting the cancellation token when getting diagnostics. This + // is because diagnostics can be quite expensive, and we want to allow hosts to bail out if + // they no longer need the information (for example, if the user started editing again). + var cancellationToken: CancellationToken | undefined; + + var scanner: Scanner | undefined; + + var Symbol = objectAllocator.getSymbolConstructor(); + var Type = objectAllocator.getTypeConstructor(); + var Signature = objectAllocator.getSignatureConstructor(); + + var typeCount = 0; + var symbolCount = 0; + var totalInstantiationCount = 0; + var instantiationCount = 0; + var instantiationDepth = 0; + var inlineLevel = 0; + var currentNode: Node | undefined; + var varianceTypeParameter: TypeParameter | undefined; + var isInferencePartiallyBlocked = false; + + var emptySymbols = createSymbolTable(); + var arrayVariances = [VarianceFlags.Covariant]; + + var compilerOptions = host.getCompilerOptions(); + var languageVersion = getEmitScriptTarget(compilerOptions); + var moduleKind = getEmitModuleKind(compilerOptions); + var legacyDecorators = !!compilerOptions.experimentalDecorators; + var useDefineForClassFields = getUseDefineForClassFields(compilerOptions); + var emitStandardClassFields = getEmitStandardClassFields(compilerOptions); + var allowSyntheticDefaultImports = getAllowSyntheticDefaultImports(compilerOptions); + var strictNullChecks = getStrictOptionValue(compilerOptions, "strictNullChecks"); + var strictFunctionTypes = getStrictOptionValue(compilerOptions, "strictFunctionTypes"); + var strictBindCallApply = getStrictOptionValue(compilerOptions, "strictBindCallApply"); + var strictPropertyInitialization = getStrictOptionValue(compilerOptions, "strictPropertyInitialization"); + var noImplicitAny = getStrictOptionValue(compilerOptions, "noImplicitAny"); + var noImplicitThis = getStrictOptionValue(compilerOptions, "noImplicitThis"); + var useUnknownInCatchVariables = getStrictOptionValue(compilerOptions, "useUnknownInCatchVariables"); + var exactOptionalPropertyTypes = compilerOptions.exactOptionalPropertyTypes; + + var checkBinaryExpression = createCheckBinaryExpression(); + var emitResolver = createResolver(); + var nodeBuilder = createNodeBuilder(); + var syntacticNodeBuilder = createSyntacticTypeNodeBuilder(compilerOptions, { + isEntityNameVisible, + isExpandoFunctionDeclaration, + getAllAccessorDeclarations: getAllAccessorDeclarationsForDeclaration, + requiresAddingImplicitUndefined, + isUndefinedIdentifierExpression(node: Identifier) { + Debug.assert(isExpressionNode(node)); + return getSymbolAtLocation(node) === undefinedSymbol; + }, + isDefinitelyReferenceToGlobalSymbolObject, + }); + var evaluate = createEvaluator({ + evaluateElementAccessExpression, + evaluateEntityNameExpression, + }); + + var globals = createSymbolTable(); + var undefinedSymbol = createSymbol(SymbolFlags.Property, "undefined" as __String); + undefinedSymbol.declarations = []; + + var globalThisSymbol = createSymbol(SymbolFlags.Module, "globalThis" as __String, CheckFlags.Readonly); + globalThisSymbol.exports = globals; + globalThisSymbol.declarations = []; + globals.set(globalThisSymbol.escapedName, globalThisSymbol); + + var argumentsSymbol = createSymbol(SymbolFlags.Property, "arguments" as __String); + var requireSymbol = createSymbol(SymbolFlags.Property, "require" as __String); + var isolatedModulesLikeFlagName = compilerOptions.verbatimModuleSyntax ? "verbatimModuleSyntax" : "isolatedModules"; + var canCollectSymbolAliasAccessabilityData = !compilerOptions.verbatimModuleSyntax; + + /** This will be set during calls to `getResolvedSignature` where services determines an apparent number of arguments greater than what is actually provided. */ + var apparentArgumentCount: number | undefined; + + var lastGetCombinedNodeFlagsNode: Node | undefined; + var lastGetCombinedNodeFlagsResult = NodeFlags.None; + var lastGetCombinedModifierFlagsNode: Declaration | undefined; + var lastGetCombinedModifierFlagsResult = ModifierFlags.None; + var resolveName = createNameResolver({ + compilerOptions, + requireSymbol, + argumentsSymbol, + globals, + getSymbolOfDeclaration, + error, + getRequiresScopeChangeCache, + setRequiresScopeChangeCache, + lookup: getSymbol, + onPropertyWithInvalidInitializer: checkAndReportErrorForInvalidInitializer, + onFailedToResolveSymbol, + onSuccessfullyResolvedSymbol, + }); + + var resolveNameForSymbolSuggestion = createNameResolver({ + compilerOptions, + requireSymbol, + argumentsSymbol, + globals, + getSymbolOfDeclaration, + error, + getRequiresScopeChangeCache, + setRequiresScopeChangeCache, + lookup: getSuggestionForSymbolNameLookup, + }); + // for public members that accept a Node or one of its subtypes, we must guard against + // synthetic nodes created during transformations by calling `getParseTreeNode`. + // for most of these, we perform the guard only on `checker` to avoid any possible + // extra cost of calling `getParseTreeNode` when calling these functions from inside the + // checker. + const checker: TypeChecker = { + getNodeCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.nodeCount, 0), + getIdentifierCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.identifierCount, 0), + getSymbolCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.symbolCount, symbolCount), + getTypeCount: () => typeCount, + getInstantiationCount: () => totalInstantiationCount, + getRelationCacheSizes: () => ({ + assignable: assignableRelation.size, + identity: identityRelation.size, + subtype: subtypeRelation.size, + strictSubtype: strictSubtypeRelation.size, + }), + isUndefinedSymbol: symbol => symbol === undefinedSymbol, + isArgumentsSymbol: symbol => symbol === argumentsSymbol, + isUnknownSymbol: symbol => symbol === unknownSymbol, + getMergedSymbol, + symbolIsValue, + getDiagnostics, + getGlobalDiagnostics, + getRecursionIdentity, + getUnmatchedProperties, + getTypeOfSymbolAtLocation: (symbol, locationIn) => { + const location = getParseTreeNode(locationIn); + return location ? getTypeOfSymbolAtLocation(symbol, location) : errorType; + }, + getTypeOfSymbol, + getSymbolsOfParameterPropertyDeclaration: (parameterIn, parameterName) => { + const parameter = getParseTreeNode(parameterIn, isParameter); + if (parameter === undefined) return Debug.fail("Cannot get symbols of a synthetic parameter that cannot be resolved to a parse-tree node."); + Debug.assert(isParameterPropertyDeclaration(parameter, parameter.parent)); + return getSymbolsOfParameterPropertyDeclaration(parameter, escapeLeadingUnderscores(parameterName)); + }, + getDeclaredTypeOfSymbol, + getPropertiesOfType, + getPropertyOfType: (type, name) => getPropertyOfType(type, escapeLeadingUnderscores(name)), + getPrivateIdentifierPropertyOfType: (leftType: Type, name: string, location: Node) => { + const node = getParseTreeNode(location); + if (!node) { + return undefined; + } + const propName = escapeLeadingUnderscores(name); + const lexicallyScopedIdentifier = lookupSymbolForPrivateIdentifierDeclaration(propName, node); + return lexicallyScopedIdentifier ? getPrivateIdentifierPropertyOfType(leftType, lexicallyScopedIdentifier) : undefined; + }, + getTypeOfPropertyOfType: (type, name) => getTypeOfPropertyOfType(type, escapeLeadingUnderscores(name)), + getIndexInfoOfType: (type, kind) => getIndexInfoOfType(type, kind === IndexKind.String ? stringType : numberType), + getIndexInfosOfType, + getIndexInfosOfIndexSymbol, + getSignaturesOfType, + getIndexTypeOfType: (type, kind) => getIndexTypeOfType(type, kind === IndexKind.String ? stringType : numberType), + getIndexType: type => getIndexType(type), + getBaseTypes, + getBaseTypeOfLiteralType, + getWidenedType, + getWidenedLiteralType, + getTypeFromTypeNode: nodeIn => { + const node = getParseTreeNode(nodeIn, isTypeNode); + return node ? getTypeFromTypeNode(node) : errorType; + }, + getParameterType: getTypeAtPosition, + getParameterIdentifierInfoAtPosition, + getPromisedTypeOfPromise, + getAwaitedType: type => getAwaitedType(type), + getReturnTypeOfSignature, + isNullableType, + getNullableType, + getNonNullableType, + getNonOptionalType: removeOptionalTypeMarker, + getTypeArguments, + typeToTypeNode: nodeBuilder.typeToTypeNode, + indexInfoToIndexSignatureDeclaration: nodeBuilder.indexInfoToIndexSignatureDeclaration, + signatureToSignatureDeclaration: nodeBuilder.signatureToSignatureDeclaration, + symbolToEntityName: nodeBuilder.symbolToEntityName, + symbolToExpression: nodeBuilder.symbolToExpression, + symbolToNode: nodeBuilder.symbolToNode, + symbolToTypeParameterDeclarations: nodeBuilder.symbolToTypeParameterDeclarations, + symbolToParameterDeclaration: nodeBuilder.symbolToParameterDeclaration, + typeParameterToDeclaration: nodeBuilder.typeParameterToDeclaration, + getSymbolsInScope: (locationIn, meaning) => { + const location = getParseTreeNode(locationIn); + return location ? getSymbolsInScope(location, meaning) : []; + }, + getSymbolAtLocation: nodeIn => { + const node = getParseTreeNode(nodeIn); + // set ignoreErrors: true because any lookups invoked by the API shouldn't cause any new errors + return node ? getSymbolAtLocation(node, /*ignoreErrors*/ true) : undefined; + }, + getIndexInfosAtLocation: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node ? getIndexInfosAtLocation(node) : undefined; + }, + getShorthandAssignmentValueSymbol: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node ? getShorthandAssignmentValueSymbol(node) : undefined; + }, + getExportSpecifierLocalTargetSymbol: nodeIn => { + const node = getParseTreeNode(nodeIn, isExportSpecifier); + return node ? getExportSpecifierLocalTargetSymbol(node) : undefined; + }, + getExportSymbolOfSymbol(symbol) { + return getMergedSymbol(symbol.exportSymbol || symbol); + }, + getTypeAtLocation: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node ? getTypeOfNode(node) : errorType; + }, + getTypeOfAssignmentPattern: nodeIn => { + const node = getParseTreeNode(nodeIn, isAssignmentPattern); + return node && getTypeOfAssignmentPattern(node) || errorType; + }, + getPropertySymbolOfDestructuringAssignment: locationIn => { + const location = getParseTreeNode(locationIn, isIdentifier); + return location ? getPropertySymbolOfDestructuringAssignment(location) : undefined; + }, + signatureToString: (signature, enclosingDeclaration, flags, kind) => { + return signatureToString(signature, getParseTreeNode(enclosingDeclaration), flags, kind); + }, + typeToString: (type, enclosingDeclaration, flags) => { + return typeToString(type, getParseTreeNode(enclosingDeclaration), flags); + }, + symbolToString: (symbol, enclosingDeclaration, meaning, flags) => { + return symbolToString(symbol, getParseTreeNode(enclosingDeclaration), meaning, flags); + }, + typePredicateToString: (predicate, enclosingDeclaration, flags) => { + return typePredicateToString(predicate, getParseTreeNode(enclosingDeclaration), flags); + }, + writeSignature: (signature, enclosingDeclaration, flags, kind, writer) => { + return signatureToString(signature, getParseTreeNode(enclosingDeclaration), flags, kind, writer); + }, + writeType: (type, enclosingDeclaration, flags, writer) => { + return typeToString(type, getParseTreeNode(enclosingDeclaration), flags, writer); + }, + writeSymbol: (symbol, enclosingDeclaration, meaning, flags, writer) => { + return symbolToString(symbol, getParseTreeNode(enclosingDeclaration), meaning, flags, writer); + }, + writeTypePredicate: (predicate, enclosingDeclaration, flags, writer) => { + return typePredicateToString(predicate, getParseTreeNode(enclosingDeclaration), flags, writer); + }, + getAugmentedPropertiesOfType, + getRootSymbols, + getSymbolOfExpando, + getContextualType: (nodeIn: Expression, contextFlags?: ContextFlags) => { + const node = getParseTreeNode(nodeIn, isExpression); + if (!node) { + return undefined; + } + if (contextFlags! & ContextFlags.Completions) { + return runWithInferenceBlockedFromSourceNode(node, () => getContextualType(node, contextFlags)); + } + return getContextualType(node, contextFlags); + }, + getContextualTypeForObjectLiteralElement: nodeIn => { + const node = getParseTreeNode(nodeIn, isObjectLiteralElementLike); + return node ? getContextualTypeForObjectLiteralElement(node, /*contextFlags*/ undefined) : undefined; + }, + getContextualTypeForArgumentAtIndex: (nodeIn, argIndex) => { + const node = getParseTreeNode(nodeIn, isCallLikeExpression); + return node && getContextualTypeForArgumentAtIndex(node, argIndex); + }, + getContextualTypeForJsxAttribute: nodeIn => { + const node = getParseTreeNode(nodeIn, isJsxAttributeLike); + return node && getContextualTypeForJsxAttribute(node, /*contextFlags*/ undefined); + }, + isContextSensitive, + getTypeOfPropertyOfContextualType, + getFullyQualifiedName, + getResolvedSignature: (node, candidatesOutArray, argumentCount) => getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.Normal), + getCandidateSignaturesForStringLiteralCompletions, + getResolvedSignatureForSignatureHelp: (node, candidatesOutArray, argumentCount) => runWithoutResolvedSignatureCaching(node, () => getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.IsForSignatureHelp)), + getExpandedParameters, + hasEffectiveRestParameter, + containsArgumentsReference, + getConstantValue: nodeIn => { + const node = getParseTreeNode(nodeIn, canHaveConstantValue); + return node ? getConstantValue(node) : undefined; + }, + isValidPropertyAccess: (nodeIn, propertyName) => { + const node = getParseTreeNode(nodeIn, isPropertyAccessOrQualifiedNameOrImportTypeNode); + return !!node && isValidPropertyAccess(node, escapeLeadingUnderscores(propertyName)); + }, + isValidPropertyAccessForCompletions: (nodeIn, type, property) => { + const node = getParseTreeNode(nodeIn, isPropertyAccessExpression); + return !!node && isValidPropertyAccessForCompletions(node, type, property); + }, + getSignatureFromDeclaration: declarationIn => { + const declaration = getParseTreeNode(declarationIn, isFunctionLike); + return declaration ? getSignatureFromDeclaration(declaration) : undefined; + }, + isImplementationOfOverload: nodeIn => { + const node = getParseTreeNode(nodeIn, isFunctionLike); + return node ? isImplementationOfOverload(node) : undefined; + }, + getImmediateAliasedSymbol, + getAliasedSymbol: resolveAlias, + getEmitResolver, + requiresAddingImplicitUndefined, + getExportsOfModule: getExportsOfModuleAsArray, + getExportsAndPropertiesOfModule, + forEachExportAndPropertyOfModule, + getSymbolWalker: createGetSymbolWalker( + getRestTypeOfSignature, + getTypePredicateOfSignature, + getReturnTypeOfSignature, + getBaseTypes, + resolveStructuredTypeMembers, + getTypeOfSymbol, + getResolvedSymbol, + getConstraintOfTypeParameter, + getFirstIdentifier, + getTypeArguments, + ), + getAmbientModules, + getJsxIntrinsicTagNamesAt, + isOptionalParameter: nodeIn => { + const node = getParseTreeNode(nodeIn, isParameter); + return node ? isOptionalParameter(node) : false; + }, + tryGetMemberInModuleExports: (name, symbol) => tryGetMemberInModuleExports(escapeLeadingUnderscores(name), symbol), + tryGetMemberInModuleExportsAndProperties: (name, symbol) => tryGetMemberInModuleExportsAndProperties(escapeLeadingUnderscores(name), symbol), + tryFindAmbientModule: moduleName => tryFindAmbientModule(moduleName, /*withAugmentations*/ true), + tryFindAmbientModuleWithoutAugmentations: moduleName => { + // we deliberately exclude augmentations + // since we are only interested in declarations of the module itself + return tryFindAmbientModule(moduleName, /*withAugmentations*/ false); + }, + getApparentType, + getUnionType, + isTypeAssignableTo, + createAnonymousType, + createSignature, + createSymbol, + createIndexInfo, + getAnyType: () => anyType, + getStringType: () => stringType, + getStringLiteralType, + getNumberType: () => numberType, + getNumberLiteralType, + getBigIntType: () => bigintType, + getBigIntLiteralType, + createPromiseType, + createArrayType, + getElementTypeOfArrayType, + getBooleanType: () => booleanType, + getFalseType: (fresh?) => fresh ? falseType : regularFalseType, + getTrueType: (fresh?) => fresh ? trueType : regularTrueType, + getVoidType: () => voidType, + getUndefinedType: () => undefinedType, + getNullType: () => nullType, + getESSymbolType: () => esSymbolType, + getNeverType: () => neverType, + getOptionalType: () => optionalType, + getPromiseType: () => getGlobalPromiseType(/*reportErrors*/ false), + getPromiseLikeType: () => getGlobalPromiseLikeType(/*reportErrors*/ false), + getAsyncIterableType: () => { + const type = getGlobalAsyncIterableType(/*reportErrors*/ false); + if (type === emptyGenericType) return undefined; + return type; + }, + isSymbolAccessible, + isArrayType, + isTupleType, + isArrayLikeType, + isEmptyAnonymousObjectType, + isTypeInvalidDueToUnionDiscriminant, + getExactOptionalProperties, + getAllPossiblePropertiesOfTypes, + getSuggestedSymbolForNonexistentProperty, + getSuggestedSymbolForNonexistentJSXAttribute, + getSuggestedSymbolForNonexistentSymbol: (location, name, meaning) => getSuggestedSymbolForNonexistentSymbol(location, escapeLeadingUnderscores(name), meaning), + getSuggestedSymbolForNonexistentModule, + getSuggestedSymbolForNonexistentClassMember, + getBaseConstraintOfType, + getDefaultFromTypeParameter: type => type && type.flags & TypeFlags.TypeParameter ? getDefaultFromTypeParameter(type as TypeParameter) : undefined, + resolveName(name, location, meaning, excludeGlobals) { + return resolveName(location, escapeLeadingUnderscores(name), meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false, excludeGlobals); + }, + getJsxNamespace: n => unescapeLeadingUnderscores(getJsxNamespace(n)), + getJsxFragmentFactory: n => { + const jsxFragmentFactory = getJsxFragmentFactoryEntity(n); + return jsxFragmentFactory && unescapeLeadingUnderscores(getFirstIdentifier(jsxFragmentFactory).escapedText); + }, + getAccessibleSymbolChain, + getTypePredicateOfSignature, + resolveExternalModuleName: moduleSpecifierIn => { + const moduleSpecifier = getParseTreeNode(moduleSpecifierIn, isExpression); + return moduleSpecifier && resolveExternalModuleName(moduleSpecifier, moduleSpecifier, /*ignoreErrors*/ true); + }, + resolveExternalModuleSymbol, + tryGetThisTypeAt: (nodeIn, includeGlobalThis, container) => { + const node = getParseTreeNode(nodeIn); + return node && tryGetThisTypeAt(node, includeGlobalThis, container); + }, + getTypeArgumentConstraint: nodeIn => { + const node = getParseTreeNode(nodeIn, isTypeNode); + return node && getTypeArgumentConstraint(node); + }, + getSuggestionDiagnostics: (fileIn, ct) => { + const file = getParseTreeNode(fileIn, isSourceFile) || Debug.fail("Could not determine parsed source file."); + if (skipTypeChecking(file, compilerOptions, host)) { + return emptyArray; + } + + let diagnostics: DiagnosticWithLocation[] | undefined; + try { + // Record the cancellation token so it can be checked later on during checkSourceElement. + // Do this in a finally block so we can ensure that it gets reset back to nothing after + // this call is done. + cancellationToken = ct; + + // Ensure file is type checked, with _eager_ diagnostic production, so identifiers are registered as potentially unused + checkSourceFileWithEagerDiagnostics(file); + Debug.assert(!!(getNodeLinks(file).flags & NodeCheckFlags.TypeChecked)); + + diagnostics = addRange(diagnostics, suggestionDiagnostics.getDiagnostics(file.fileName)); + checkUnusedIdentifiers(getPotentiallyUnusedIdentifiers(file), (containingNode, kind, diag) => { + if (!containsParseError(containingNode) && !unusedIsError(kind, !!(containingNode.flags & NodeFlags.Ambient))) { + (diagnostics || (diagnostics = [])).push({ ...diag, category: DiagnosticCategory.Suggestion }); + } + }); + + return diagnostics || emptyArray; + } + finally { + cancellationToken = undefined; + } + }, + + runWithCancellationToken: (token, callback) => { + try { + cancellationToken = token; + return callback(checker); + } + finally { + cancellationToken = undefined; + } + }, + + getLocalTypeParametersOfClassOrInterfaceOrTypeAlias, + isDeclarationVisible, + isPropertyAccessible, + getTypeOnlyAliasDeclaration, + getMemberOverrideModifierStatus, + isTypeParameterPossiblyReferenced, + typeHasCallOrConstructSignatures, + getSymbolFlags, + }; + + function getCandidateSignaturesForStringLiteralCompletions(call: CallLikeExpression, editingArgument: Node) { + const candidatesSet = new Set(); + const candidates: Signature[] = []; + + // first, get candidates when inference is blocked from the source node. + runWithInferenceBlockedFromSourceNode(editingArgument, () => getResolvedSignatureWorker(call, candidates, /*argumentCount*/ undefined, CheckMode.Normal)); + for (const candidate of candidates) { + candidatesSet.add(candidate); + } + + // reset candidates for second pass + candidates.length = 0; + + // next, get candidates where the source node is considered for inference. + runWithoutResolvedSignatureCaching(editingArgument, () => getResolvedSignatureWorker(call, candidates, /*argumentCount*/ undefined, CheckMode.Normal)); + for (const candidate of candidates) { + candidatesSet.add(candidate); + } + + return arrayFrom(candidatesSet); + } + + function runWithoutResolvedSignatureCaching(node: Node | undefined, fn: () => T): T { + node = findAncestor(node, isCallLikeOrFunctionLikeExpression); + if (node) { + const cachedResolvedSignatures = []; + const cachedTypes = []; + while (node) { + const nodeLinks = getNodeLinks(node); + cachedResolvedSignatures.push([nodeLinks, nodeLinks.resolvedSignature] as const); + nodeLinks.resolvedSignature = undefined; + if (isFunctionExpressionOrArrowFunction(node)) { + const symbolLinks = getSymbolLinks(getSymbolOfDeclaration(node)); + const type = symbolLinks.type; + cachedTypes.push([symbolLinks, type] as const); + symbolLinks.type = undefined; + } + node = findAncestor(node.parent, isCallLikeOrFunctionLikeExpression); + } + const result = fn(); + for (const [nodeLinks, resolvedSignature] of cachedResolvedSignatures) { + nodeLinks.resolvedSignature = resolvedSignature; + } + for (const [symbolLinks, type] of cachedTypes) { + symbolLinks.type = type; + } + return result; + } + return fn(); + } + + function runWithInferenceBlockedFromSourceNode(node: Node | undefined, fn: () => T): T { + const containingCall = findAncestor(node, isCallLikeExpression); + if (containingCall) { + let toMarkSkip = node!; + do { + getNodeLinks(toMarkSkip).skipDirectInference = true; + toMarkSkip = toMarkSkip.parent; + } + while (toMarkSkip && toMarkSkip !== containingCall); + } + + isInferencePartiallyBlocked = true; + const result = runWithoutResolvedSignatureCaching(node, fn); + isInferencePartiallyBlocked = false; + + if (containingCall) { + let toMarkSkip = node!; + do { + getNodeLinks(toMarkSkip).skipDirectInference = undefined; + toMarkSkip = toMarkSkip.parent; + } + while (toMarkSkip && toMarkSkip !== containingCall); + } + return result; + } + + function getResolvedSignatureWorker(nodeIn: CallLikeExpression, candidatesOutArray: Signature[] | undefined, argumentCount: number | undefined, checkMode: CheckMode): Signature | undefined { + const node = getParseTreeNode(nodeIn, isCallLikeExpression); + apparentArgumentCount = argumentCount; + const res = !node ? undefined : getResolvedSignature(node, candidatesOutArray, checkMode); + apparentArgumentCount = undefined; + return res; + } + + var tupleTypes = new Map(); + var unionTypes = new Map(); + var unionOfUnionTypes = new Map(); + var intersectionTypes = new Map(); + var stringLiteralTypes = new Map(); + var numberLiteralTypes = new Map(); + var bigIntLiteralTypes = new Map(); + var enumLiteralTypes = new Map(); + var indexedAccessTypes = new Map(); + var templateLiteralTypes = new Map(); + var stringMappingTypes = new Map(); + var substitutionTypes = new Map(); + var subtypeReductionCache = new Map(); + var decoratorContextOverrideTypeCache = new Map(); + var cachedTypes = new Map(); + var evolvingArrayTypes: EvolvingArrayType[] = []; + var undefinedProperties: SymbolTable = new Map(); + var markerTypes = new Set(); + + var unknownSymbol = createSymbol(SymbolFlags.Property, "unknown" as __String); + var resolvingSymbol = createSymbol(0, InternalSymbolName.Resolving); + var unresolvedSymbols = new Map(); + var errorTypes = new Map(); + + // We specifically create the `undefined` and `null` types before any other types that can occur in + // unions such that they are given low type IDs and occur first in the sorted list of union constituents. + // We can then just examine the first constituent(s) of a union to check for their presence. + + var seenIntrinsicNames = new Set(); + + var anyType = createIntrinsicType(TypeFlags.Any, "any"); + var autoType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.NonInferrableType, "auto"); + var wildcardType = createIntrinsicType(TypeFlags.Any, "any", /*objectFlags*/ undefined, "wildcard"); + var blockedStringType = createIntrinsicType(TypeFlags.Any, "any", /*objectFlags*/ undefined, "blocked string"); + var errorType = createIntrinsicType(TypeFlags.Any, "error"); + var unresolvedType = createIntrinsicType(TypeFlags.Any, "unresolved"); + var nonInferrableAnyType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.ContainsWideningType, "non-inferrable"); + var intrinsicMarkerType = createIntrinsicType(TypeFlags.Any, "intrinsic"); + var unknownType = createIntrinsicType(TypeFlags.Unknown, "unknown"); + var undefinedType = createIntrinsicType(TypeFlags.Undefined, "undefined"); + var undefinedWideningType = strictNullChecks ? undefinedType : createIntrinsicType(TypeFlags.Undefined, "undefined", ObjectFlags.ContainsWideningType, "widening"); + var missingType = createIntrinsicType(TypeFlags.Undefined, "undefined", /*objectFlags*/ undefined, "missing"); + var undefinedOrMissingType = exactOptionalPropertyTypes ? missingType : undefinedType; + var optionalType = createIntrinsicType(TypeFlags.Undefined, "undefined", /*objectFlags*/ undefined, "optional"); + var nullType = createIntrinsicType(TypeFlags.Null, "null"); + var nullWideningType = strictNullChecks ? nullType : createIntrinsicType(TypeFlags.Null, "null", ObjectFlags.ContainsWideningType, "widening"); + var stringType = createIntrinsicType(TypeFlags.String, "string"); + var numberType = createIntrinsicType(TypeFlags.Number, "number"); + var bigintType = createIntrinsicType(TypeFlags.BigInt, "bigint"); + var falseType = createIntrinsicType(TypeFlags.BooleanLiteral, "false", /*objectFlags*/ undefined, "fresh") as FreshableIntrinsicType; + var regularFalseType = createIntrinsicType(TypeFlags.BooleanLiteral, "false") as FreshableIntrinsicType; + var trueType = createIntrinsicType(TypeFlags.BooleanLiteral, "true", /*objectFlags*/ undefined, "fresh") as FreshableIntrinsicType; + var regularTrueType = createIntrinsicType(TypeFlags.BooleanLiteral, "true") as FreshableIntrinsicType; + trueType.regularType = regularTrueType; + trueType.freshType = trueType; + regularTrueType.regularType = regularTrueType; + regularTrueType.freshType = trueType; + falseType.regularType = regularFalseType; + falseType.freshType = falseType; + regularFalseType.regularType = regularFalseType; + regularFalseType.freshType = falseType; + var booleanType = getUnionType([regularFalseType, regularTrueType]); + var esSymbolType = createIntrinsicType(TypeFlags.ESSymbol, "symbol"); + var voidType = createIntrinsicType(TypeFlags.Void, "void"); + var neverType = createIntrinsicType(TypeFlags.Never, "never"); + var silentNeverType = createIntrinsicType(TypeFlags.Never, "never", ObjectFlags.NonInferrableType, "silent"); + var implicitNeverType = createIntrinsicType(TypeFlags.Never, "never", /*objectFlags*/ undefined, "implicit"); + var unreachableNeverType = createIntrinsicType(TypeFlags.Never, "never", /*objectFlags*/ undefined, "unreachable"); + var nonPrimitiveType = createIntrinsicType(TypeFlags.NonPrimitive, "object"); + var stringOrNumberType = getUnionType([stringType, numberType]); + var stringNumberSymbolType = getUnionType([stringType, numberType, esSymbolType]); + var numberOrBigIntType = getUnionType([numberType, bigintType]); + var templateConstraintType = getUnionType([stringType, numberType, booleanType, bigintType, nullType, undefinedType]) as UnionType; + var numericStringType = getTemplateLiteralType(["", ""], [numberType]); // The `${number}` type + + var restrictiveMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? getRestrictiveTypeParameter(t as TypeParameter) : t, () => "(restrictive mapper)"); + var permissiveMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? wildcardType : t, () => "(permissive mapper)"); + var uniqueLiteralType = createIntrinsicType(TypeFlags.Never, "never", /*objectFlags*/ undefined, "unique literal"); // `uniqueLiteralType` is a special `never` flagged by union reduction to behave as a literal + var uniqueLiteralMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? uniqueLiteralType : t, () => "(unique literal mapper)"); // replace all type parameters with the unique literal type (disregarding constraints) + var outofbandVarianceMarkerHandler: ((onlyUnreliable: boolean) => void) | undefined; + var reportUnreliableMapper = makeFunctionTypeMapper(t => { + if (outofbandVarianceMarkerHandler && (t === markerSuperType || t === markerSubType || t === markerOtherType)) { + outofbandVarianceMarkerHandler(/*onlyUnreliable*/ true); + } + return t; + }, () => "(unmeasurable reporter)"); + var reportUnmeasurableMapper = makeFunctionTypeMapper(t => { + if (outofbandVarianceMarkerHandler && (t === markerSuperType || t === markerSubType || t === markerOtherType)) { + outofbandVarianceMarkerHandler(/*onlyUnreliable*/ false); + } + return t; + }, () => "(unreliable reporter)"); + + var emptyObjectType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var emptyJsxObjectType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + emptyJsxObjectType.objectFlags |= ObjectFlags.JsxAttributes; + + var emptyTypeLiteralSymbol = createSymbol(SymbolFlags.TypeLiteral, InternalSymbolName.Type); + emptyTypeLiteralSymbol.members = createSymbolTable(); + var emptyTypeLiteralType = createAnonymousType(emptyTypeLiteralSymbol, emptySymbols, emptyArray, emptyArray, emptyArray); + + var unknownEmptyObjectType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var unknownUnionType = strictNullChecks ? getUnionType([undefinedType, nullType, unknownEmptyObjectType]) : unknownType; + + var emptyGenericType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray) as ObjectType as GenericType; + emptyGenericType.instantiations = new Map(); + + var anyFunctionType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + // The anyFunctionType contains the anyFunctionType by definition. The flag is further propagated + // in getPropagatingFlagsOfTypes, and it is checked in inferFromTypes. + anyFunctionType.objectFlags |= ObjectFlags.NonInferrableType; + + var noConstraintType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var circularConstraintType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var resolvingDefaultType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + + var markerSuperType = createTypeParameter(); + var markerSubType = createTypeParameter(); + markerSubType.constraint = markerSuperType; + var markerOtherType = createTypeParameter(); + + var markerSuperTypeForCheck = createTypeParameter(); + var markerSubTypeForCheck = createTypeParameter(); + markerSubTypeForCheck.constraint = markerSuperTypeForCheck; + + var noTypePredicate = createTypePredicate(TypePredicateKind.Identifier, "<>", 0, anyType); + + var anySignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, anyType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + var unknownSignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, errorType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + var resolvingSignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, anyType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + var silentNeverSignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, silentNeverType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + + var enumNumberIndexInfo = createIndexInfo(numberType, stringType, /*isReadonly*/ true); + + var iterationTypesCache = new Map(); // cache for common IterationTypes instances + var noIterationTypes: IterationTypes = { + get yieldType(): Type { + return Debug.fail("Not supported"); + }, + get returnType(): Type { + return Debug.fail("Not supported"); + }, + get nextType(): Type { + return Debug.fail("Not supported"); + }, + }; + + var anyIterationTypes = createIterationTypes(anyType, anyType, anyType); + var anyIterationTypesExceptNext = createIterationTypes(anyType, anyType, unknownType); + var defaultIterationTypes = createIterationTypes(neverType, anyType, undefinedType); // default iteration types for `Iterator`. + + var asyncIterationTypesResolver: IterationTypesResolver = { + iterableCacheKey: "iterationTypesOfAsyncIterable", + iteratorCacheKey: "iterationTypesOfAsyncIterator", + iteratorSymbolName: "asyncIterator", + getGlobalIteratorType: getGlobalAsyncIteratorType, + getGlobalIterableType: getGlobalAsyncIterableType, + getGlobalIterableIteratorType: getGlobalAsyncIterableIteratorType, + getGlobalGeneratorType: getGlobalAsyncGeneratorType, + resolveIterationType: (type, errorNode) => getAwaitedType(type, errorNode, Diagnostics.Type_of_await_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member), + mustHaveANextMethodDiagnostic: Diagnostics.An_async_iterator_must_have_a_next_method, + mustBeAMethodDiagnostic: Diagnostics.The_0_property_of_an_async_iterator_must_be_a_method, + mustHaveAValueDiagnostic: Diagnostics.The_type_returned_by_the_0_method_of_an_async_iterator_must_be_a_promise_for_a_type_with_a_value_property, + }; + + var syncIterationTypesResolver: IterationTypesResolver = { + iterableCacheKey: "iterationTypesOfIterable", + iteratorCacheKey: "iterationTypesOfIterator", + iteratorSymbolName: "iterator", + getGlobalIteratorType, + getGlobalIterableType, + getGlobalIterableIteratorType, + getGlobalGeneratorType, + resolveIterationType: (type, _errorNode) => type, + mustHaveANextMethodDiagnostic: Diagnostics.An_iterator_must_have_a_next_method, + mustBeAMethodDiagnostic: Diagnostics.The_0_property_of_an_iterator_must_be_a_method, + mustHaveAValueDiagnostic: Diagnostics.The_type_returned_by_the_0_method_of_an_iterator_must_have_a_value_property, + }; + + interface DuplicateInfoForSymbol { + readonly firstFileLocations: Declaration[]; + readonly secondFileLocations: Declaration[]; + readonly isBlockScoped: boolean; + } + interface DuplicateInfoForFiles { + readonly firstFile: SourceFile; + readonly secondFile: SourceFile; + /** Key is symbol name. */ + readonly conflictingSymbols: Map; + } + /** Key is "/path/to/a.ts|/path/to/b.ts". */ + var amalgamatedDuplicates: Map | undefined; + var reverseMappedCache = new Map(); + var ambientModulesCache: Symbol[] | undefined; + /** + * List of every ambient module with a "*" wildcard. + * Unlike other ambient modules, these can't be stored in `globals` because symbol tables only deal with exact matches. + * This is only used if there is no exact match. + */ + var patternAmbientModules: PatternAmbientModule[]; + var patternAmbientModuleAugmentations: Map | undefined; + + var globalObjectType: ObjectType; + var globalFunctionType: ObjectType; + var globalCallableFunctionType: ObjectType; + var globalNewableFunctionType: ObjectType; + var globalArrayType: GenericType; + var globalReadonlyArrayType: GenericType; + var globalStringType: ObjectType; + var globalNumberType: ObjectType; + var globalBooleanType: ObjectType; + var globalRegExpType: ObjectType; + var globalThisType: GenericType; + var anyArrayType: Type; + var autoArrayType: Type; + var anyReadonlyArrayType: Type; + var deferredGlobalNonNullableTypeAlias: Symbol; + + // The library files are only loaded when the feature is used. + // This allows users to just specify library files they want to used through --lib + // and they will not get an error from not having unrelated library files + var deferredGlobalESSymbolConstructorSymbol: Symbol | undefined; + var deferredGlobalESSymbolConstructorTypeSymbol: Symbol | undefined; + var deferredGlobalESSymbolType: ObjectType | undefined; + var deferredGlobalTypedPropertyDescriptorType: GenericType; + var deferredGlobalPromiseType: GenericType | undefined; + var deferredGlobalPromiseLikeType: GenericType | undefined; + var deferredGlobalPromiseConstructorSymbol: Symbol | undefined; + var deferredGlobalPromiseConstructorLikeType: ObjectType | undefined; + var deferredGlobalIterableType: GenericType | undefined; + var deferredGlobalIteratorType: GenericType | undefined; + var deferredGlobalIterableIteratorType: GenericType | undefined; + var deferredGlobalGeneratorType: GenericType | undefined; + var deferredGlobalIteratorYieldResultType: GenericType | undefined; + var deferredGlobalIteratorReturnResultType: GenericType | undefined; + var deferredGlobalAsyncIterableType: GenericType | undefined; + var deferredGlobalAsyncIteratorType: GenericType | undefined; + var deferredGlobalAsyncIterableIteratorType: GenericType | undefined; + var deferredGlobalAsyncGeneratorType: GenericType | undefined; + var deferredGlobalTemplateStringsArrayType: ObjectType | undefined; + var deferredGlobalImportMetaType: ObjectType; + var deferredGlobalImportMetaExpressionType: ObjectType; + var deferredGlobalImportCallOptionsType: ObjectType | undefined; + var deferredGlobalImportAttributesType: ObjectType | undefined; + var deferredGlobalDisposableType: ObjectType | undefined; + var deferredGlobalAsyncDisposableType: ObjectType | undefined; + var deferredGlobalExtractSymbol: Symbol | undefined; + var deferredGlobalOmitSymbol: Symbol | undefined; + var deferredGlobalAwaitedSymbol: Symbol | undefined; + var deferredGlobalBigIntType: ObjectType | undefined; + var deferredGlobalNaNSymbol: Symbol | undefined; + var deferredGlobalRecordSymbol: Symbol | undefined; + var deferredGlobalClassDecoratorContextType: GenericType | undefined; + var deferredGlobalClassMethodDecoratorContextType: GenericType | undefined; + var deferredGlobalClassGetterDecoratorContextType: GenericType | undefined; + var deferredGlobalClassSetterDecoratorContextType: GenericType | undefined; + var deferredGlobalClassAccessorDecoratorContextType: GenericType | undefined; + var deferredGlobalClassAccessorDecoratorTargetType: GenericType | undefined; + var deferredGlobalClassAccessorDecoratorResultType: GenericType | undefined; + var deferredGlobalClassFieldDecoratorContextType: GenericType | undefined; + + var allPotentiallyUnusedIdentifiers = new Map(); // key is file name + + var flowLoopStart = 0; + var flowLoopCount = 0; + var sharedFlowCount = 0; + var flowAnalysisDisabled = false; + var flowInvocationCount = 0; + var lastFlowNode: FlowNode | undefined; + var lastFlowNodeReachable: boolean; + var flowTypeCache: Type[] | undefined; + + var contextualTypeNodes: Node[] = []; + var contextualTypes: (Type | undefined)[] = []; + var contextualIsCache: boolean[] = []; + var contextualTypeCount = 0; + + var inferenceContextNodes: Node[] = []; + var inferenceContexts: (InferenceContext | undefined)[] = []; + var inferenceContextCount = 0; + + var emptyStringType = getStringLiteralType(""); + var zeroType = getNumberLiteralType(0); + var zeroBigIntType = getBigIntLiteralType({ negative: false, base10Value: "0" }); + + var resolutionTargets: TypeSystemEntity[] = []; + var resolutionResults: boolean[] = []; + var resolutionPropertyNames: TypeSystemPropertyName[] = []; + var resolutionStart = 0; + var inVarianceComputation = false; + + var suggestionCount = 0; + var maximumSuggestionCount = 10; + var mergedSymbols: Symbol[] = []; + var symbolLinks: SymbolLinks[] = []; + var nodeLinks: NodeLinks[] = []; + var flowLoopCaches: Map[] = []; + var flowLoopNodes: FlowNode[] = []; + var flowLoopKeys: string[] = []; + var flowLoopTypes: Type[][] = []; + var sharedFlowNodes: FlowNode[] = []; + var sharedFlowTypes: FlowType[] = []; + var flowNodeReachable: (boolean | undefined)[] = []; + var flowNodePostSuper: (boolean | undefined)[] = []; + var potentialThisCollisions: Node[] = []; + var potentialNewTargetCollisions: Node[] = []; + var potentialWeakMapSetCollisions: Node[] = []; + var potentialReflectCollisions: Node[] = []; + var potentialUnusedRenamedBindingElementsInTypes: BindingElement[] = []; + var awaitedTypeStack: number[] = []; + var reverseMappedSourceStack: Type[] = []; + var reverseMappedTargetStack: Type[] = []; + var reverseExpandingFlags = ExpandingFlags.None; + + var diagnostics = createDiagnosticCollection(); + var suggestionDiagnostics = createDiagnosticCollection(); + + var typeofType = createTypeofType(); + + var _jsxNamespace: __String; + var _jsxFactoryEntity: EntityName | undefined; + + var subtypeRelation = new Map(); + var strictSubtypeRelation = new Map(); + var assignableRelation = new Map(); + var comparableRelation = new Map(); + var identityRelation = new Map(); + var enumRelation = new Map(); + + // Extensions suggested for path imports when module resolution is node16 or higher. + // The first element of each tuple is the extension a file has. + // The second element of each tuple is the extension that should be used in a path import. + // e.g. if we want to import file `foo.mts`, we should write `import {} from "./foo.mjs". + var suggestedExtensions: [string, string][] = [ + [".mts", ".mjs"], + [".ts", ".js"], + [".cts", ".cjs"], + [".mjs", ".mjs"], + [".js", ".js"], + [".cjs", ".cjs"], + [".tsx", compilerOptions.jsx === JsxEmit.Preserve ? ".jsx" : ".js"], + [".jsx", ".jsx"], + [".json", ".json"], + ]; + /* eslint-enable no-var */ + + initializeTypeChecker(); + + return checker; + + function isDefinitelyReferenceToGlobalSymbolObject(node: Node): boolean { + if (!isPropertyAccessExpression(node)) return false; + if (!isIdentifier(node.name)) return false; + if (!isPropertyAccessExpression(node.expression) && !isIdentifier(node.expression)) return false; + if (isIdentifier(node.expression)) { + // Exactly `Symbol.something` and `Symbol` either does not resolve or definitely resolves to the global Symbol + return idText(node.expression) === "Symbol" && getResolvedSymbol(node.expression) === (getGlobalSymbol("Symbol" as __String, SymbolFlags.Value | SymbolFlags.ExportValue, /*diagnostic*/ undefined) || unknownSymbol); + } + if (!isIdentifier(node.expression.expression)) return false; + // Exactly `globalThis.Symbol.something` and `globalThis` resolves to the global `globalThis` + return idText(node.expression.name) === "Symbol" && idText(node.expression.expression) === "globalThis" && getResolvedSymbol(node.expression.expression) === globalThisSymbol; + } + + function getCachedType(key: string | undefined) { + return key ? cachedTypes.get(key) : undefined; + } + + function setCachedType(key: string | undefined, type: Type) { + if (key) cachedTypes.set(key, type); + return type; + } + + function getJsxNamespace(location: Node | undefined): __String { + if (location) { + const file = getSourceFileOfNode(location); + if (file) { + if (isJsxOpeningFragment(location)) { + if (file.localJsxFragmentNamespace) { + return file.localJsxFragmentNamespace; + } + const jsxFragmentPragma = file.pragmas.get("jsxfrag"); + if (jsxFragmentPragma) { + const chosenPragma = isArray(jsxFragmentPragma) ? jsxFragmentPragma[0] : jsxFragmentPragma; + file.localJsxFragmentFactory = parseIsolatedEntityName(chosenPragma.arguments.factory, languageVersion); + visitNode(file.localJsxFragmentFactory, markAsSynthetic, isEntityName); + if (file.localJsxFragmentFactory) { + return file.localJsxFragmentNamespace = getFirstIdentifier(file.localJsxFragmentFactory).escapedText; + } + } + const entity = getJsxFragmentFactoryEntity(location); + if (entity) { + file.localJsxFragmentFactory = entity; + return file.localJsxFragmentNamespace = getFirstIdentifier(entity).escapedText; + } + } + else { + const localJsxNamespace = getLocalJsxNamespace(file); + if (localJsxNamespace) { + return file.localJsxNamespace = localJsxNamespace; + } + } + } + } + if (!_jsxNamespace) { + _jsxNamespace = "React" as __String; + if (compilerOptions.jsxFactory) { + _jsxFactoryEntity = parseIsolatedEntityName(compilerOptions.jsxFactory, languageVersion); + visitNode(_jsxFactoryEntity, markAsSynthetic); + if (_jsxFactoryEntity) { + _jsxNamespace = getFirstIdentifier(_jsxFactoryEntity).escapedText; + } + } + else if (compilerOptions.reactNamespace) { + _jsxNamespace = escapeLeadingUnderscores(compilerOptions.reactNamespace); + } + } + if (!_jsxFactoryEntity) { + _jsxFactoryEntity = factory.createQualifiedName(factory.createIdentifier(unescapeLeadingUnderscores(_jsxNamespace)), "createElement"); + } + return _jsxNamespace; + } + + function getLocalJsxNamespace(file: SourceFile): __String | undefined { + if (file.localJsxNamespace) { + return file.localJsxNamespace; + } + const jsxPragma = file.pragmas.get("jsx"); + if (jsxPragma) { + const chosenPragma = isArray(jsxPragma) ? jsxPragma[0] : jsxPragma; + file.localJsxFactory = parseIsolatedEntityName(chosenPragma.arguments.factory, languageVersion); + visitNode(file.localJsxFactory, markAsSynthetic, isEntityName); + if (file.localJsxFactory) { + return file.localJsxNamespace = getFirstIdentifier(file.localJsxFactory).escapedText; + } + } + } + + function markAsSynthetic(node: T): VisitResult { + setTextRangePosEnd(node, -1, -1); + return visitEachChildWorker(node, markAsSynthetic, /*context*/ undefined); + } + + function getEmitResolver(sourceFile: SourceFile, cancellationToken: CancellationToken, skipDiagnostics?: boolean) { + // Ensure we have all the type information in place for this file so that all the + // emitter questions of this resolver will return the right information. + if (!skipDiagnostics) getDiagnostics(sourceFile, cancellationToken); + return emitResolver; + } + + function lookupOrIssueError(location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + const diagnostic = location + ? createDiagnosticForNode(location, message, ...args) + : createCompilerDiagnostic(message, ...args); + const existing = diagnostics.lookup(diagnostic); + if (existing) { + return existing; + } + else { + diagnostics.add(diagnostic); + return diagnostic; + } + } + + function errorSkippedOn(key: keyof CompilerOptions, location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + const diagnostic = error(location, message, ...args); + diagnostic.skippedOn = key; + return diagnostic; + } + + function createError(location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + return location + ? createDiagnosticForNode(location, message, ...args) + : createCompilerDiagnostic(message, ...args); + } + + function error(location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + const diagnostic = createError(location, message, ...args); + diagnostics.add(diagnostic); + return diagnostic; + } + + function addErrorOrSuggestion(isError: boolean, diagnostic: Diagnostic) { + if (isError) { + diagnostics.add(diagnostic); + } + else { + suggestionDiagnostics.add({ ...diagnostic, category: DiagnosticCategory.Suggestion }); + } + } + function errorOrSuggestion(isError: boolean, location: Node, message: DiagnosticMessage | DiagnosticMessageChain, ...args: DiagnosticArguments): void { + // Pseudo-synthesized input node + if (location.pos < 0 || location.end < 0) { + if (!isError) { + return; // Drop suggestions (we have no span to suggest on) + } + // Issue errors globally + const file = getSourceFileOfNode(location); + addErrorOrSuggestion(isError, "message" in message ? createFileDiagnostic(file, 0, 0, message, ...args) : createDiagnosticForFileFromMessageChain(file, message)); // eslint-disable-line local/no-in-operator + return; + } + addErrorOrSuggestion(isError, "message" in message ? createDiagnosticForNode(location, message, ...args) : createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(location), location, message)); // eslint-disable-line local/no-in-operator + } + + function errorAndMaybeSuggestAwait( + location: Node, + maybeMissingAwait: boolean, + message: DiagnosticMessage, + ...args: DiagnosticArguments + ): Diagnostic { + const diagnostic = error(location, message, ...args); + if (maybeMissingAwait) { + const related = createDiagnosticForNode(location, Diagnostics.Did_you_forget_to_use_await); + addRelatedInfo(diagnostic, related); + } + return diagnostic; + } + + function addDeprecatedSuggestionWorker(declarations: Node | Node[], diagnostic: DiagnosticWithLocation) { + const deprecatedTag = Array.isArray(declarations) ? forEach(declarations, getJSDocDeprecatedTag) : getJSDocDeprecatedTag(declarations); + if (deprecatedTag) { + addRelatedInfo( + diagnostic, + createDiagnosticForNode(deprecatedTag, Diagnostics.The_declaration_was_marked_as_deprecated_here), + ); + } + // We call `addRelatedInfo()` before adding the diagnostic to prevent duplicates. + suggestionDiagnostics.add(diagnostic); + return diagnostic; + } + + function isDeprecatedSymbol(symbol: Symbol) { + const parentSymbol = getParentOfSymbol(symbol); + if (parentSymbol && length(symbol.declarations) > 1) { + return parentSymbol.flags & SymbolFlags.Interface ? some(symbol.declarations, isDeprecatedDeclaration) : every(symbol.declarations, isDeprecatedDeclaration); + } + return !!symbol.valueDeclaration && isDeprecatedDeclaration(symbol.valueDeclaration) + || length(symbol.declarations) && every(symbol.declarations, isDeprecatedDeclaration); + } + + function isDeprecatedDeclaration(declaration: Declaration) { + return !!(getCombinedNodeFlagsCached(declaration) & NodeFlags.Deprecated); + } + + function addDeprecatedSuggestion(location: Node, declarations: Node[], deprecatedEntity: string) { + const diagnostic = createDiagnosticForNode(location, Diagnostics._0_is_deprecated, deprecatedEntity); + return addDeprecatedSuggestionWorker(declarations, diagnostic); + } + + function addDeprecatedSuggestionWithSignature(location: Node, declaration: Node, deprecatedEntity: string | undefined, signatureString: string) { + const diagnostic = deprecatedEntity + ? createDiagnosticForNode(location, Diagnostics.The_signature_0_of_1_is_deprecated, signatureString, deprecatedEntity) + : createDiagnosticForNode(location, Diagnostics._0_is_deprecated, signatureString); + return addDeprecatedSuggestionWorker(declaration, diagnostic); + } + + function createSymbol(flags: SymbolFlags, name: __String, checkFlags?: CheckFlags) { + symbolCount++; + const symbol = new Symbol(flags | SymbolFlags.Transient, name) as TransientSymbol; + symbol.links = new SymbolLinks() as TransientSymbolLinks; + symbol.links.checkFlags = checkFlags || CheckFlags.None; + return symbol; + } + + function createParameter(name: __String, type: Type) { + const symbol = createSymbol(SymbolFlags.FunctionScopedVariable, name); + symbol.links.type = type; + return symbol; + } + + function createProperty(name: __String, type: Type) { + const symbol = createSymbol(SymbolFlags.Property, name); + symbol.links.type = type; + return symbol; + } + + function getExcludedSymbolFlags(flags: SymbolFlags): SymbolFlags { + let result: SymbolFlags = 0; + if (flags & SymbolFlags.BlockScopedVariable) result |= SymbolFlags.BlockScopedVariableExcludes; + if (flags & SymbolFlags.FunctionScopedVariable) result |= SymbolFlags.FunctionScopedVariableExcludes; + if (flags & SymbolFlags.Property) result |= SymbolFlags.PropertyExcludes; + if (flags & SymbolFlags.EnumMember) result |= SymbolFlags.EnumMemberExcludes; + if (flags & SymbolFlags.Function) result |= SymbolFlags.FunctionExcludes; + if (flags & SymbolFlags.Class) result |= SymbolFlags.ClassExcludes; + if (flags & SymbolFlags.Interface) result |= SymbolFlags.InterfaceExcludes; + if (flags & SymbolFlags.RegularEnum) result |= SymbolFlags.RegularEnumExcludes; + if (flags & SymbolFlags.ConstEnum) result |= SymbolFlags.ConstEnumExcludes; + if (flags & SymbolFlags.ValueModule) result |= SymbolFlags.ValueModuleExcludes; + if (flags & SymbolFlags.Method) result |= SymbolFlags.MethodExcludes; + if (flags & SymbolFlags.GetAccessor) result |= SymbolFlags.GetAccessorExcludes; + if (flags & SymbolFlags.SetAccessor) result |= SymbolFlags.SetAccessorExcludes; + if (flags & SymbolFlags.TypeParameter) result |= SymbolFlags.TypeParameterExcludes; + if (flags & SymbolFlags.TypeAlias) result |= SymbolFlags.TypeAliasExcludes; + if (flags & SymbolFlags.Alias) result |= SymbolFlags.AliasExcludes; + return result; + } + + function recordMergedSymbol(target: Symbol, source: Symbol) { + if (!source.mergeId) { + source.mergeId = nextMergeId; + nextMergeId++; + } + mergedSymbols[source.mergeId] = target; + } + + function cloneSymbol(symbol: Symbol): TransientSymbol { + const result = createSymbol(symbol.flags, symbol.escapedName); + result.declarations = symbol.declarations ? symbol.declarations.slice() : []; + result.parent = symbol.parent; + if (symbol.valueDeclaration) result.valueDeclaration = symbol.valueDeclaration; + if (symbol.constEnumOnlyModule) result.constEnumOnlyModule = true; + if (symbol.members) result.members = new Map(symbol.members); + if (symbol.exports) result.exports = new Map(symbol.exports); + recordMergedSymbol(result, symbol); + return result; + } + + /** + * Note: if target is transient, then it is mutable, and mergeSymbol with both mutate and return it. + * If target is not transient, mergeSymbol will produce a transient clone, mutate that and return it. + */ + function mergeSymbol(target: Symbol, source: Symbol, unidirectional = false): Symbol { + if ( + !(target.flags & getExcludedSymbolFlags(source.flags)) || + (source.flags | target.flags) & SymbolFlags.Assignment + ) { + if (source === target) { + // This can happen when an export assigned namespace exports something also erroneously exported at the top level + // See `declarationFileNoCrashOnExtraExportModifier` for an example + return target; + } + if (!(target.flags & SymbolFlags.Transient)) { + const resolvedTarget = resolveSymbol(target); + if (resolvedTarget === unknownSymbol) { + return source; + } + if ( + !(resolvedTarget.flags & getExcludedSymbolFlags(source.flags)) || + (source.flags | resolvedTarget.flags) & SymbolFlags.Assignment + ) { + target = cloneSymbol(resolvedTarget); + } + else { + reportMergeSymbolError(target, source); + return source; + } + } + // Javascript static-property-assignment declarations always merge, even though they are also values + if (source.flags & SymbolFlags.ValueModule && target.flags & SymbolFlags.ValueModule && target.constEnumOnlyModule && !source.constEnumOnlyModule) { + // reset flag when merging instantiated module into value module that has only const enums + target.constEnumOnlyModule = false; + } + target.flags |= source.flags; + if (source.valueDeclaration) { + setValueDeclaration(target, source.valueDeclaration); + } + addRange(target.declarations, source.declarations); + if (source.members) { + if (!target.members) target.members = createSymbolTable(); + mergeSymbolTable(target.members, source.members, unidirectional); + } + if (source.exports) { + if (!target.exports) target.exports = createSymbolTable(); + mergeSymbolTable(target.exports, source.exports, unidirectional); + } + if (!unidirectional) { + recordMergedSymbol(target, source); + } + } + else if (target.flags & SymbolFlags.NamespaceModule) { + // Do not report an error when merging `var globalThis` with the built-in `globalThis`, + // as we will already report a "Declaration name conflicts..." error, and this error + // won't make much sense. + if (target !== globalThisSymbol) { + error( + source.declarations && getNameOfDeclaration(source.declarations[0]), + Diagnostics.Cannot_augment_module_0_with_value_exports_because_it_resolves_to_a_non_module_entity, + symbolToString(target), + ); + } + } + else { + reportMergeSymbolError(target, source); + } + return target; + + function reportMergeSymbolError(target: Symbol, source: Symbol) { + const isEitherEnum = !!(target.flags & SymbolFlags.Enum || source.flags & SymbolFlags.Enum); + const isEitherBlockScoped = !!(target.flags & SymbolFlags.BlockScopedVariable || source.flags & SymbolFlags.BlockScopedVariable); + const message = isEitherEnum ? Diagnostics.Enum_declarations_can_only_merge_with_namespace_or_other_enum_declarations + : isEitherBlockScoped ? Diagnostics.Cannot_redeclare_block_scoped_variable_0 + : Diagnostics.Duplicate_identifier_0; + const sourceSymbolFile = source.declarations && getSourceFileOfNode(source.declarations[0]); + const targetSymbolFile = target.declarations && getSourceFileOfNode(target.declarations[0]); + + const isSourcePlainJs = isPlainJsFile(sourceSymbolFile, compilerOptions.checkJs); + const isTargetPlainJs = isPlainJsFile(targetSymbolFile, compilerOptions.checkJs); + const symbolName = symbolToString(source); + + // Collect top-level duplicate identifier errors into one mapping, so we can then merge their diagnostics if there are a bunch + if (sourceSymbolFile && targetSymbolFile && amalgamatedDuplicates && !isEitherEnum && sourceSymbolFile !== targetSymbolFile) { + const firstFile = comparePaths(sourceSymbolFile.path, targetSymbolFile.path) === Comparison.LessThan ? sourceSymbolFile : targetSymbolFile; + const secondFile = firstFile === sourceSymbolFile ? targetSymbolFile : sourceSymbolFile; + const filesDuplicates = getOrUpdate(amalgamatedDuplicates, `${firstFile.path}|${secondFile.path}`, (): DuplicateInfoForFiles => ({ firstFile, secondFile, conflictingSymbols: new Map() })); + const conflictingSymbolInfo = getOrUpdate(filesDuplicates.conflictingSymbols, symbolName, (): DuplicateInfoForSymbol => ({ isBlockScoped: isEitherBlockScoped, firstFileLocations: [], secondFileLocations: [] })); + if (!isSourcePlainJs) addDuplicateLocations(conflictingSymbolInfo.firstFileLocations, source); + if (!isTargetPlainJs) addDuplicateLocations(conflictingSymbolInfo.secondFileLocations, target); + } + else { + if (!isSourcePlainJs) addDuplicateDeclarationErrorsForSymbols(source, message, symbolName, target); + if (!isTargetPlainJs) addDuplicateDeclarationErrorsForSymbols(target, message, symbolName, source); + } + } + + function addDuplicateLocations(locs: Declaration[], symbol: Symbol): void { + if (symbol.declarations) { + for (const decl of symbol.declarations) { + pushIfUnique(locs, decl); + } + } + } + } + + function addDuplicateDeclarationErrorsForSymbols(target: Symbol, message: DiagnosticMessage, symbolName: string, source: Symbol) { + forEach(target.declarations, node => { + addDuplicateDeclarationError(node, message, symbolName, source.declarations); + }); + } + + function addDuplicateDeclarationError(node: Declaration, message: DiagnosticMessage, symbolName: string, relatedNodes: readonly Declaration[] | undefined) { + const errorNode = (getExpandoInitializer(node, /*isPrototypeAssignment*/ false) ? getNameOfExpando(node) : getNameOfDeclaration(node)) || node; + const err = lookupOrIssueError(errorNode, message, symbolName); + for (const relatedNode of relatedNodes || emptyArray) { + const adjustedNode = (getExpandoInitializer(relatedNode, /*isPrototypeAssignment*/ false) ? getNameOfExpando(relatedNode) : getNameOfDeclaration(relatedNode)) || relatedNode; + if (adjustedNode === errorNode) continue; + err.relatedInformation = err.relatedInformation || []; + const leadingMessage = createDiagnosticForNode(adjustedNode, Diagnostics._0_was_also_declared_here, symbolName); + const followOnMessage = createDiagnosticForNode(adjustedNode, Diagnostics.and_here); + if (length(err.relatedInformation) >= 5 || some(err.relatedInformation, r => compareDiagnostics(r, followOnMessage) === Comparison.EqualTo || compareDiagnostics(r, leadingMessage) === Comparison.EqualTo)) continue; + addRelatedInfo(err, !length(err.relatedInformation) ? leadingMessage : followOnMessage); + } + } + + function combineSymbolTables(first: SymbolTable | undefined, second: SymbolTable | undefined): SymbolTable | undefined { + if (!first?.size) return second; + if (!second?.size) return first; + const combined = createSymbolTable(); + mergeSymbolTable(combined, first); + mergeSymbolTable(combined, second); + return combined; + } + + function mergeSymbolTable(target: SymbolTable, source: SymbolTable, unidirectional = false) { + source.forEach((sourceSymbol, id) => { + const targetSymbol = target.get(id); + target.set(id, targetSymbol ? mergeSymbol(targetSymbol, sourceSymbol, unidirectional) : getMergedSymbol(sourceSymbol)); + }); + } + + function mergeModuleAugmentation(moduleName: StringLiteral | Identifier): void { + const moduleAugmentation = moduleName.parent as ModuleDeclaration; + if (moduleAugmentation.symbol.declarations?.[0] !== moduleAugmentation) { + // this is a combined symbol for multiple augmentations within the same file. + // its symbol already has accumulated information for all declarations + // so we need to add it just once - do the work only for first declaration + Debug.assert(moduleAugmentation.symbol.declarations!.length > 1); + return; + } + + if (isGlobalScopeAugmentation(moduleAugmentation)) { + mergeSymbolTable(globals, moduleAugmentation.symbol.exports!); + } + else { + // find a module that about to be augmented + // do not validate names of augmentations that are defined in ambient context + const moduleNotFoundError = !(moduleName.parent.parent.flags & NodeFlags.Ambient) + ? Diagnostics.Invalid_module_name_in_augmentation_module_0_cannot_be_found + : undefined; + let mainModule = resolveExternalModuleNameWorker(moduleName, moduleName, moduleNotFoundError, /*isForAugmentation*/ true); + if (!mainModule) { + return; + } + // obtain item referenced by 'export=' + mainModule = resolveExternalModuleSymbol(mainModule); + if (mainModule.flags & SymbolFlags.Namespace) { + // If we're merging an augmentation to a pattern ambient module, we want to + // perform the merge unidirectionally from the augmentation ('a.foo') to + // the pattern ('*.foo'), so that 'getMergedSymbol()' on a.foo gives you + // all the exports both from the pattern and from the augmentation, but + // 'getMergedSymbol()' on *.foo only gives you exports from *.foo. + if (some(patternAmbientModules, module => mainModule === module.symbol)) { + const merged = mergeSymbol(moduleAugmentation.symbol, mainModule, /*unidirectional*/ true); + if (!patternAmbientModuleAugmentations) { + patternAmbientModuleAugmentations = new Map(); + } + // moduleName will be a StringLiteral since this is not `declare global`. + patternAmbientModuleAugmentations.set((moduleName as StringLiteral).text, merged); + } + else { + if (mainModule.exports?.get(InternalSymbolName.ExportStar) && moduleAugmentation.symbol.exports?.size) { + // We may need to merge the module augmentation's exports into the target symbols of the resolved exports + const resolvedExports = getResolvedMembersOrExportsOfSymbol(mainModule, MembersOrExportsResolutionKind.resolvedExports); + for (const [key, value] of arrayFrom(moduleAugmentation.symbol.exports.entries())) { + if (resolvedExports.has(key) && !mainModule.exports.has(key)) { + mergeSymbol(resolvedExports.get(key)!, value); + } + } + } + mergeSymbol(mainModule, moduleAugmentation.symbol); + } + } + else { + // moduleName will be a StringLiteral since this is not `declare global`. + error(moduleName, Diagnostics.Cannot_augment_module_0_because_it_resolves_to_a_non_module_entity, (moduleName as StringLiteral).text); + } + } + } + + function addUndefinedToGlobalsOrErrorOnRedeclaration() { + const name = undefinedSymbol.escapedName; + const targetSymbol = globals.get(name); + if (targetSymbol) { + forEach(targetSymbol.declarations, declaration => { + // checkTypeNameIsReserved will have added better diagnostics for type declarations. + if (!isTypeDeclaration(declaration)) { + diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Declaration_name_conflicts_with_built_in_global_identifier_0, unescapeLeadingUnderscores(name))); + } + }); + } + else { + globals.set(name, undefinedSymbol); + } + } + + function getSymbolLinks(symbol: Symbol): SymbolLinks { + if (symbol.flags & SymbolFlags.Transient) return (symbol as TransientSymbol).links; + const id = getSymbolId(symbol); + return symbolLinks[id] ??= new SymbolLinks(); + } + + function getNodeLinks(node: Node): NodeLinks { + const nodeId = getNodeId(node); + return nodeLinks[nodeId] || (nodeLinks[nodeId] = new (NodeLinks as any)()); + } + + function getSymbol(symbols: SymbolTable, name: __String, meaning: SymbolFlags): Symbol | undefined { + if (meaning) { + const symbol = getMergedSymbol(symbols.get(name)); + if (symbol) { + if (symbol.flags & meaning) { + return symbol; + } + if (symbol.flags & SymbolFlags.Alias) { + const targetFlags = getSymbolFlags(symbol); + // `targetFlags` will be `SymbolFlags.All` if an error occurred in alias resolution; this avoids cascading errors + if (targetFlags & meaning) { + return symbol; + } + } + } + } + // return undefined if we can't find a symbol. + } + + /** + * Get symbols that represent parameter-property-declaration as parameter and as property declaration + * @param parameter a parameterDeclaration node + * @param parameterName a name of the parameter to get the symbols for. + * @return a tuple of two symbols + */ + function getSymbolsOfParameterPropertyDeclaration(parameter: ParameterPropertyDeclaration, parameterName: __String): [Symbol, Symbol] { + const constructorDeclaration = parameter.parent; + const classDeclaration = parameter.parent.parent; + + const parameterSymbol = getSymbol(constructorDeclaration.locals!, parameterName, SymbolFlags.Value); + const propertySymbol = getSymbol(getMembersOfSymbol(classDeclaration.symbol), parameterName, SymbolFlags.Value); + + if (parameterSymbol && propertySymbol) { + return [parameterSymbol, propertySymbol]; + } + + return Debug.fail("There should exist two symbols, one as property declaration and one as parameter declaration"); + } + + function isBlockScopedNameDeclaredBeforeUse(declaration: Declaration, usage: Node): boolean { + const declarationFile = getSourceFileOfNode(declaration); + const useFile = getSourceFileOfNode(usage); + const declContainer = getEnclosingBlockScopeContainer(declaration); + if (declarationFile !== useFile) { + if ( + (moduleKind && (declarationFile.externalModuleIndicator || useFile.externalModuleIndicator)) || + (!compilerOptions.outFile) || + isInTypeQuery(usage) || + declaration.flags & NodeFlags.Ambient + ) { + // nodes are in different files and order cannot be determined + return true; + } + // declaration is after usage + // can be legal if usage is deferred (i.e. inside function or in initializer of instance property) + if (isUsedInFunctionOrInstanceProperty(usage, declaration)) { + return true; + } + const sourceFiles = host.getSourceFiles(); + return sourceFiles.indexOf(declarationFile) <= sourceFiles.indexOf(useFile); + } + + // deferred usage in a type context is always OK regardless of the usage position: + if (!!(usage.flags & NodeFlags.JSDoc) || isInTypeQuery(usage) || isInAmbientOrTypeNode(usage)) { + return true; + } + + if (declaration.pos <= usage.pos && !(isPropertyDeclaration(declaration) && isThisProperty(usage.parent) && !declaration.initializer && !declaration.exclamationToken)) { + // declaration is before usage + if (declaration.kind === SyntaxKind.BindingElement) { + // still might be illegal if declaration and usage are both binding elements (eg var [a = b, b = b] = [1, 2]) + const errorBindingElement = getAncestor(usage, SyntaxKind.BindingElement) as BindingElement; + if (errorBindingElement) { + return findAncestor(errorBindingElement, isBindingElement) !== findAncestor(declaration, isBindingElement) || + declaration.pos < errorBindingElement.pos; + } + // or it might be illegal if usage happens before parent variable is declared (eg var [a] = a) + return isBlockScopedNameDeclaredBeforeUse(getAncestor(declaration, SyntaxKind.VariableDeclaration) as Declaration, usage); + } + else if (declaration.kind === SyntaxKind.VariableDeclaration) { + // still might be illegal if usage is in the initializer of the variable declaration (eg var a = a) + return !isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration as VariableDeclaration, usage); + } + else if (isClassLike(declaration)) { + // still might be illegal if the usage is within a computed property name in the class (eg class A { static p = "a"; [A.p]() {} }) + // or when used within a decorator in the class (e.g. `@dec(A.x) class A { static x = "x" }`), + // except when used in a function that is not an IIFE (e.g., `@dec(() => A.x) class A { ... }`) + const container = findAncestor(usage, n => + n === declaration ? "quit" : + isComputedPropertyName(n) ? n.parent.parent === declaration : + !legacyDecorators && isDecorator(n) && (n.parent === declaration || + isMethodDeclaration(n.parent) && n.parent.parent === declaration || + isGetOrSetAccessorDeclaration(n.parent) && n.parent.parent === declaration || + isPropertyDeclaration(n.parent) && n.parent.parent === declaration || + isParameter(n.parent) && n.parent.parent.parent === declaration)); + if (!container) { + return true; + } + if (!legacyDecorators && isDecorator(container)) { + return !!findAncestor(usage, n => n === container ? "quit" : isFunctionLike(n) && !getImmediatelyInvokedFunctionExpression(n)); + } + return false; + } + else if (isPropertyDeclaration(declaration)) { + // still might be illegal if a self-referencing property initializer (eg private x = this.x) + return !isPropertyImmediatelyReferencedWithinDeclaration(declaration, usage, /*stopAtAnyPropertyDeclaration*/ false); + } + else if (isParameterPropertyDeclaration(declaration, declaration.parent)) { + // foo = this.bar is illegal in emitStandardClassFields when bar is a parameter property + return !(emitStandardClassFields + && getContainingClass(declaration) === getContainingClass(usage) + && isUsedInFunctionOrInstanceProperty(usage, declaration)); + } + return true; + } + + // declaration is after usage, but it can still be legal if usage is deferred: + // 1. inside an export specifier + // 2. inside a function + // 3. inside an instance property initializer, a reference to a non-instance property + // (except when emitStandardClassFields: true and the reference is to a parameter property) + // 4. inside a static property initializer, a reference to a static method in the same class + // 5. inside a TS export= declaration (since we will move the export statement during emit to avoid TDZ) + if (usage.parent.kind === SyntaxKind.ExportSpecifier || (usage.parent.kind === SyntaxKind.ExportAssignment && (usage.parent as ExportAssignment).isExportEquals)) { + // export specifiers do not use the variable, they only make it available for use + return true; + } + // When resolving symbols for exports, the `usage` location passed in can be the export site directly + if (usage.kind === SyntaxKind.ExportAssignment && (usage as ExportAssignment).isExportEquals) { + return true; + } + + if (isUsedInFunctionOrInstanceProperty(usage, declaration)) { + if ( + emitStandardClassFields + && getContainingClass(declaration) + && (isPropertyDeclaration(declaration) || isParameterPropertyDeclaration(declaration, declaration.parent)) + ) { + return !isPropertyImmediatelyReferencedWithinDeclaration(declaration, usage, /*stopAtAnyPropertyDeclaration*/ true); + } + else { + return true; + } + } + return false; + + function isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration: VariableDeclaration, usage: Node): boolean { + switch (declaration.parent.parent.kind) { + case SyntaxKind.VariableStatement: + case SyntaxKind.ForStatement: + case SyntaxKind.ForOfStatement: + // variable statement/for/for-of statement case, + // use site should not be inside variable declaration (initializer of declaration or binding element) + if (isSameScopeDescendentOf(usage, declaration, declContainer)) { + return true; + } + break; + } + + // ForIn/ForOf case - use site should not be used in expression part + const grandparent = declaration.parent.parent; + return isForInOrOfStatement(grandparent) && isSameScopeDescendentOf(usage, grandparent.expression, declContainer); + } + + function isUsedInFunctionOrInstanceProperty(usage: Node, declaration: Node): boolean { + return !!findAncestor(usage, current => { + if (current === declContainer) { + return "quit"; + } + if (isFunctionLike(current)) { + return true; + } + if (isClassStaticBlockDeclaration(current)) { + return declaration.pos < usage.pos; + } + + const propertyDeclaration = tryCast(current.parent, isPropertyDeclaration); + if (propertyDeclaration) { + const initializerOfProperty = propertyDeclaration.initializer === current; + if (initializerOfProperty) { + if (isStatic(current.parent)) { + if (declaration.kind === SyntaxKind.MethodDeclaration) { + return true; + } + if (isPropertyDeclaration(declaration) && getContainingClass(usage) === getContainingClass(declaration)) { + const propName = declaration.name; + if (isIdentifier(propName) || isPrivateIdentifier(propName)) { + const type = getTypeOfSymbol(getSymbolOfDeclaration(declaration)); + const staticBlocks = filter(declaration.parent.members, isClassStaticBlockDeclaration); + if (isPropertyInitializedInStaticBlocks(propName, type, staticBlocks, declaration.parent.pos, current.pos)) { + return true; + } + } + } + } + else { + const isDeclarationInstanceProperty = declaration.kind === SyntaxKind.PropertyDeclaration && !isStatic(declaration); + if (!isDeclarationInstanceProperty || getContainingClass(usage) !== getContainingClass(declaration)) { + return true; + } + } + } + } + return false; + }); + } + + /** stopAtAnyPropertyDeclaration is used for detecting ES-standard class field use-before-def errors */ + function isPropertyImmediatelyReferencedWithinDeclaration(declaration: PropertyDeclaration | ParameterPropertyDeclaration, usage: Node, stopAtAnyPropertyDeclaration: boolean) { + // always legal if usage is after declaration + if (usage.end > declaration.end) { + return false; + } + + // still might be legal if usage is deferred (e.g. x: any = () => this.x) + // otherwise illegal if immediately referenced within the declaration (e.g. x: any = this.x) + const ancestorChangingReferenceScope = findAncestor(usage, (node: Node) => { + if (node === declaration) { + return "quit"; + } + + switch (node.kind) { + case SyntaxKind.ArrowFunction: + return true; + case SyntaxKind.PropertyDeclaration: + // even when stopping at any property declaration, they need to come from the same class + return stopAtAnyPropertyDeclaration && + (isPropertyDeclaration(declaration) && node.parent === declaration.parent + || isParameterPropertyDeclaration(declaration, declaration.parent) && node.parent === declaration.parent.parent) + ? "quit" : true; + case SyntaxKind.Block: + switch (node.parent.kind) { + case SyntaxKind.GetAccessor: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.SetAccessor: + return true; + default: + return false; + } + default: + return false; + } + }); + + return ancestorChangingReferenceScope === undefined; + } + } + + function getRequiresScopeChangeCache(node: FunctionLikeDeclaration) { + return getNodeLinks(node).declarationRequiresScopeChange; + } + function setRequiresScopeChangeCache(node: FunctionLikeDeclaration, value: boolean) { + getNodeLinks(node).declarationRequiresScopeChange = value; + } + // The invalid initializer error is needed in two situation: + // 1. When result is undefined, after checking for a missing "this." + // 2. When result is defined + function checkAndReportErrorForInvalidInitializer(errorLocation: Node | undefined, name: __String, propertyWithInvalidInitializer: PropertyDeclaration, result: Symbol | undefined) { + if (!emitStandardClassFields) { + if (errorLocation && !result && checkAndReportErrorForMissingPrefix(errorLocation, name, name)) { + return true; + } + // We have a match, but the reference occurred within a property initializer and the identifier also binds + // to a local variable in the constructor where the code will be emitted. Note that this is actually allowed + // with emitStandardClassFields because the scope semantics are different. + error( + errorLocation, + errorLocation && propertyWithInvalidInitializer.type && textRangeContainsPositionInclusive(propertyWithInvalidInitializer.type, errorLocation.pos) + ? Diagnostics.Type_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor + : Diagnostics.Initializer_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor, + declarationNameToString(propertyWithInvalidInitializer.name), + diagnosticName(name), + ); + return true; + } + return false; + } + function onFailedToResolveSymbol( + errorLocation: Node | undefined, + nameArg: __String | Identifier, + meaning: SymbolFlags, + nameNotFoundMessage: DiagnosticMessage, + ) { + const name = isString(nameArg) ? nameArg : (nameArg as Identifier).escapedText; + addLazyDiagnostic(() => { + if ( + !errorLocation || + errorLocation.parent.kind !== SyntaxKind.JSDocLink && + !checkAndReportErrorForMissingPrefix(errorLocation, name, nameArg) && + !checkAndReportErrorForExtendingInterface(errorLocation) && + !checkAndReportErrorForUsingTypeAsNamespace(errorLocation, name, meaning) && + !checkAndReportErrorForExportingPrimitiveType(errorLocation, name) && + !checkAndReportErrorForUsingNamespaceAsTypeOrValue(errorLocation, name, meaning) && + !checkAndReportErrorForUsingTypeAsValue(errorLocation, name, meaning) && + !checkAndReportErrorForUsingValueAsType(errorLocation, name, meaning) + ) { + let suggestion: Symbol | undefined; + let suggestedLib: string | undefined; + // Report missing lib first + if (nameArg) { + suggestedLib = getSuggestedLibForNonExistentName(nameArg); + if (suggestedLib) { + error(errorLocation, nameNotFoundMessage, diagnosticName(nameArg), suggestedLib); + } + } + // then spelling suggestions + if (!suggestedLib && suggestionCount < maximumSuggestionCount) { + suggestion = getSuggestedSymbolForNonexistentSymbol(errorLocation, name, meaning); + const isGlobalScopeAugmentationDeclaration = suggestion?.valueDeclaration && isAmbientModule(suggestion.valueDeclaration) && isGlobalScopeAugmentation(suggestion.valueDeclaration); + if (isGlobalScopeAugmentationDeclaration) { + suggestion = undefined; + } + if (suggestion) { + const suggestionName = symbolToString(suggestion); + const isUncheckedJS = isUncheckedJSSuggestion(errorLocation, suggestion, /*excludeClasses*/ false); + const message = meaning === SymbolFlags.Namespace || + nameArg && typeof nameArg !== "string" && nodeIsSynthesized(nameArg) ? + Diagnostics.Cannot_find_namespace_0_Did_you_mean_1 + : isUncheckedJS ? Diagnostics.Could_not_find_name_0_Did_you_mean_1 + : Diagnostics.Cannot_find_name_0_Did_you_mean_1; + const diagnostic = createError(errorLocation, message, diagnosticName(nameArg), suggestionName); + diagnostic.canonicalHead = getCanonicalDiagnostic(nameNotFoundMessage, diagnosticName(nameArg)); + addErrorOrSuggestion(!isUncheckedJS, diagnostic); + if (suggestion.valueDeclaration) { + addRelatedInfo( + diagnostic, + createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestionName), + ); + } + } + } + // And then fall back to unspecified "not found" + if (!suggestion && !suggestedLib && nameArg) { + error(errorLocation, nameNotFoundMessage, diagnosticName(nameArg)); + } + suggestionCount++; + } + }); + } + + function onSuccessfullyResolvedSymbol( + errorLocation: Node | undefined, + result: Symbol, + meaning: SymbolFlags, + lastLocation: Node | undefined, + associatedDeclarationForContainingInitializerOrBindingName: ParameterDeclaration | BindingElement | undefined, + withinDeferredContext: boolean, + ) { + addLazyDiagnostic(() => { + const name = result.escapedName; + const isInExternalModule = lastLocation && isSourceFile(lastLocation) && isExternalOrCommonJsModule(lastLocation); + // Only check for block-scoped variable if we have an error location and are looking for the + // name with variable meaning + // For example, + // declare module foo { + // interface bar {} + // } + // const foo/*1*/: foo/*2*/.bar; + // The foo at /*1*/ and /*2*/ will share same symbol with two meanings: + // block-scoped variable and namespace module. However, only when we + // try to resolve name in /*1*/ which is used in variable position, + // we want to check for block-scoped + if ( + errorLocation && + (meaning & SymbolFlags.BlockScopedVariable || + ((meaning & SymbolFlags.Class || meaning & SymbolFlags.Enum) && (meaning & SymbolFlags.Value) === SymbolFlags.Value)) + ) { + const exportOrLocalSymbol = getExportSymbolOfValueSymbolIfExported(result); + if (exportOrLocalSymbol.flags & SymbolFlags.BlockScopedVariable || exportOrLocalSymbol.flags & SymbolFlags.Class || exportOrLocalSymbol.flags & SymbolFlags.Enum) { + checkResolvedBlockScopedVariable(exportOrLocalSymbol, errorLocation); + } + } + + // If we're in an external module, we can't reference value symbols created from UMD export declarations + if (isInExternalModule && (meaning & SymbolFlags.Value) === SymbolFlags.Value && !(errorLocation!.flags & NodeFlags.JSDoc)) { + const merged = getMergedSymbol(result); + if (length(merged.declarations) && every(merged.declarations, d => isNamespaceExportDeclaration(d) || isSourceFile(d) && !!d.symbol.globalExports)) { + errorOrSuggestion(!compilerOptions.allowUmdGlobalAccess, errorLocation!, Diagnostics._0_refers_to_a_UMD_global_but_the_current_file_is_a_module_Consider_adding_an_import_instead, unescapeLeadingUnderscores(name)); + } + } + + // If we're in a parameter initializer or binding name, we can't reference the values of the parameter whose initializer we're within or parameters to the right + if (associatedDeclarationForContainingInitializerOrBindingName && !withinDeferredContext && (meaning & SymbolFlags.Value) === SymbolFlags.Value) { + const candidate = getMergedSymbol(getLateBoundSymbol(result)); + const root = getRootDeclaration(associatedDeclarationForContainingInitializerOrBindingName) as ParameterDeclaration; + // A parameter initializer or binding pattern initializer within a parameter cannot refer to itself + if (candidate === getSymbolOfDeclaration(associatedDeclarationForContainingInitializerOrBindingName)) { + error(errorLocation, Diagnostics.Parameter_0_cannot_reference_itself, declarationNameToString(associatedDeclarationForContainingInitializerOrBindingName.name)); + } + // And it cannot refer to any declarations which come after it + else if (candidate.valueDeclaration && candidate.valueDeclaration.pos > associatedDeclarationForContainingInitializerOrBindingName.pos && root.parent.locals && getSymbol(root.parent.locals, candidate.escapedName, meaning) === candidate) { + error(errorLocation, Diagnostics.Parameter_0_cannot_reference_identifier_1_declared_after_it, declarationNameToString(associatedDeclarationForContainingInitializerOrBindingName.name), declarationNameToString(errorLocation as Identifier)); + } + } + if (errorLocation && meaning & SymbolFlags.Value && result.flags & SymbolFlags.Alias && !(result.flags & SymbolFlags.Value) && !isValidTypeOnlyAliasUseSite(errorLocation)) { + const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(result, SymbolFlags.Value); + if (typeOnlyDeclaration) { + const message = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration || typeOnlyDeclaration.kind === SyntaxKind.NamespaceExport + ? Diagnostics._0_cannot_be_used_as_a_value_because_it_was_exported_using_export_type + : Diagnostics._0_cannot_be_used_as_a_value_because_it_was_imported_using_import_type; + const unescapedName = unescapeLeadingUnderscores(name); + addTypeOnlyDeclarationRelatedInfo( + error(errorLocation, message, unescapedName), + typeOnlyDeclaration, + unescapedName, + ); + } + } + + // Look at 'compilerOptions.isolatedModules' and not 'getIsolatedModules(...)' (which considers 'verbatimModuleSyntax') + // here because 'verbatimModuleSyntax' will already have an error for importing a type without 'import type'. + if (compilerOptions.isolatedModules && result && isInExternalModule && (meaning & SymbolFlags.Value) === SymbolFlags.Value) { + const isGlobal = getSymbol(globals, name, meaning) === result; + const nonValueSymbol = isGlobal && isSourceFile(lastLocation) && lastLocation.locals && getSymbol(lastLocation.locals, name, ~SymbolFlags.Value); + if (nonValueSymbol) { + const importDecl = nonValueSymbol.declarations?.find(d => d.kind === SyntaxKind.ImportSpecifier || d.kind === SyntaxKind.ImportClause || d.kind === SyntaxKind.NamespaceImport || d.kind === SyntaxKind.ImportEqualsDeclaration); + if (importDecl && !isTypeOnlyImportDeclaration(importDecl)) { + error(importDecl, Diagnostics.Import_0_conflicts_with_global_value_used_in_this_file_so_must_be_declared_with_a_type_only_import_when_isolatedModules_is_enabled, unescapeLeadingUnderscores(name)); + } + } + } + }); + } + + function addTypeOnlyDeclarationRelatedInfo(diagnostic: Diagnostic, typeOnlyDeclaration: TypeOnlyCompatibleAliasDeclaration | undefined, unescapedName: string) { + if (!typeOnlyDeclaration) return diagnostic; + return addRelatedInfo( + diagnostic, + createDiagnosticForNode( + typeOnlyDeclaration, + typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration || typeOnlyDeclaration.kind === SyntaxKind.NamespaceExport + ? Diagnostics._0_was_exported_here + : Diagnostics._0_was_imported_here, + unescapedName, + ), + ); + } + + function diagnosticName(nameArg: __String | Identifier | PrivateIdentifier) { + return isString(nameArg) ? unescapeLeadingUnderscores(nameArg as __String) : declarationNameToString(nameArg as Identifier); + } + + function checkAndReportErrorForMissingPrefix(errorLocation: Node, name: __String, nameArg: __String | Identifier): boolean { + if (!isIdentifier(errorLocation) || errorLocation.escapedText !== name || isTypeReferenceIdentifier(errorLocation) || isInTypeQuery(errorLocation)) { + return false; + } + + const container = getThisContainer(errorLocation, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + let location: Node = container; + while (location) { + if (isClassLike(location.parent)) { + const classSymbol = getSymbolOfDeclaration(location.parent); + if (!classSymbol) { + break; + } + + // Check to see if a static member exists. + const constructorType = getTypeOfSymbol(classSymbol); + if (getPropertyOfType(constructorType, name)) { + error(errorLocation, Diagnostics.Cannot_find_name_0_Did_you_mean_the_static_member_1_0, diagnosticName(nameArg), symbolToString(classSymbol)); + return true; + } + + // No static member is present. + // Check if we're in an instance method and look for a relevant instance member. + if (location === container && !isStatic(location)) { + const instanceType = (getDeclaredTypeOfSymbol(classSymbol) as InterfaceType).thisType!; // TODO: GH#18217 + if (getPropertyOfType(instanceType, name)) { + error(errorLocation, Diagnostics.Cannot_find_name_0_Did_you_mean_the_instance_member_this_0, diagnosticName(nameArg)); + return true; + } + } + } + + location = location.parent; + } + return false; + } + + function checkAndReportErrorForExtendingInterface(errorLocation: Node): boolean { + const expression = getEntityNameForExtendingInterface(errorLocation); + if (expression && resolveEntityName(expression, SymbolFlags.Interface, /*ignoreErrors*/ true)) { + error(errorLocation, Diagnostics.Cannot_extend_an_interface_0_Did_you_mean_implements, getTextOfNode(expression)); + return true; + } + return false; + } + /** + * Climbs up parents to an ExpressionWithTypeArguments, and returns its expression, + * but returns undefined if that expression is not an EntityNameExpression. + */ + function getEntityNameForExtendingInterface(node: Node): EntityNameExpression | undefined { + switch (node.kind) { + case SyntaxKind.Identifier: + case SyntaxKind.PropertyAccessExpression: + return node.parent ? getEntityNameForExtendingInterface(node.parent) : undefined; + case SyntaxKind.ExpressionWithTypeArguments: + if (isEntityNameExpression((node as ExpressionWithTypeArguments).expression)) { + return (node as ExpressionWithTypeArguments).expression as EntityNameExpression; + } + // falls through + default: + return undefined; + } + } + + function checkAndReportErrorForUsingTypeAsNamespace(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + const namespaceMeaning = SymbolFlags.Namespace | (isInJSFile(errorLocation) ? SymbolFlags.Value : 0); + if (meaning === namespaceMeaning) { + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Type & ~namespaceMeaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + const parent = errorLocation.parent; + if (symbol) { + if (isQualifiedName(parent)) { + Debug.assert(parent.left === errorLocation, "Should only be resolving left side of qualified name as a namespace"); + const propName = parent.right.escapedText; + const propType = getPropertyOfType(getDeclaredTypeOfSymbol(symbol), propName); + if (propType) { + error( + parent, + Diagnostics.Cannot_access_0_1_because_0_is_a_type_but_not_a_namespace_Did_you_mean_to_retrieve_the_type_of_the_property_1_in_0_with_0_1, + unescapeLeadingUnderscores(name), + unescapeLeadingUnderscores(propName), + ); + return true; + } + } + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_namespace_here, unescapeLeadingUnderscores(name)); + return true; + } + } + + return false; + } + + function checkAndReportErrorForUsingValueAsType(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + if (meaning & (SymbolFlags.Type & ~SymbolFlags.Namespace)) { + const symbol = resolveSymbol(resolveName(errorLocation, name, ~SymbolFlags.Type & SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + if (symbol && !(symbol.flags & SymbolFlags.Namespace)) { + error(errorLocation, Diagnostics._0_refers_to_a_value_but_is_being_used_as_a_type_here_Did_you_mean_typeof_0, unescapeLeadingUnderscores(name)); + return true; + } + } + return false; + } + + function isPrimitiveTypeName(name: __String) { + return name === "any" || name === "string" || name === "number" || name === "boolean" || name === "never" || name === "unknown"; + } + + function checkAndReportErrorForExportingPrimitiveType(errorLocation: Node, name: __String): boolean { + if (isPrimitiveTypeName(name) && errorLocation.parent.kind === SyntaxKind.ExportSpecifier) { + error(errorLocation, Diagnostics.Cannot_export_0_Only_local_declarations_can_be_exported_from_a_module, name as string); + return true; + } + return false; + } + + function checkAndReportErrorForUsingTypeAsValue(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + if (meaning & SymbolFlags.Value) { + if (isPrimitiveTypeName(name)) { + const grandparent = errorLocation.parent.parent; + if (grandparent && grandparent.parent && isHeritageClause(grandparent)) { + const heritageKind = grandparent.token; + const containerKind = grandparent.parent.kind; + if (containerKind === SyntaxKind.InterfaceDeclaration && heritageKind === SyntaxKind.ExtendsKeyword) { + error(errorLocation, Diagnostics.An_interface_cannot_extend_a_primitive_type_like_0_It_can_only_extend_other_named_object_types, unescapeLeadingUnderscores(name)); + } + else if (containerKind === SyntaxKind.ClassDeclaration && heritageKind === SyntaxKind.ExtendsKeyword) { + error(errorLocation, Diagnostics.A_class_cannot_extend_a_primitive_type_like_0_Classes_can_only_extend_constructable_values, unescapeLeadingUnderscores(name)); + } + else if (containerKind === SyntaxKind.ClassDeclaration && heritageKind === SyntaxKind.ImplementsKeyword) { + error(errorLocation, Diagnostics.A_class_cannot_implement_a_primitive_type_like_0_It_can_only_implement_other_named_object_types, unescapeLeadingUnderscores(name)); + } + } + else { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here, unescapeLeadingUnderscores(name)); + } + return true; + } + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Type & ~SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + const allFlags = symbol && getSymbolFlags(symbol); + if (symbol && allFlags !== undefined && !(allFlags & SymbolFlags.Value)) { + const rawName = unescapeLeadingUnderscores(name); + if (isES2015OrLaterConstructorName(name)) { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_es2015_or_later, rawName); + } + else if (maybeMappedType(errorLocation, symbol)) { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here_Did_you_mean_to_use_1_in_0, rawName, rawName === "K" ? "P" : "K"); + } + else { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here, rawName); + } + return true; + } + } + return false; + } + + function maybeMappedType(node: Node, symbol: Symbol) { + const container = findAncestor(node.parent, n => isComputedPropertyName(n) || isPropertySignature(n) ? false : isTypeLiteralNode(n) || "quit") as TypeLiteralNode | undefined; + if (container && container.members.length === 1) { + const type = getDeclaredTypeOfSymbol(symbol); + return !!(type.flags & TypeFlags.Union) && allTypesAssignableToKind(type, TypeFlags.StringOrNumberLiteral, /*strict*/ true); + } + return false; + } + + function isES2015OrLaterConstructorName(n: __String) { + switch (n) { + case "Promise": + case "Symbol": + case "Map": + case "WeakMap": + case "Set": + case "WeakSet": + return true; + } + return false; + } + + function checkAndReportErrorForUsingNamespaceAsTypeOrValue(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + if (meaning & (SymbolFlags.Value & ~SymbolFlags.Type)) { + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.NamespaceModule, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + if (symbol) { + error( + errorLocation, + Diagnostics.Cannot_use_namespace_0_as_a_value, + unescapeLeadingUnderscores(name), + ); + return true; + } + } + else if (meaning & (SymbolFlags.Type & ~SymbolFlags.Value)) { + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Module, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + if (symbol) { + error(errorLocation, Diagnostics.Cannot_use_namespace_0_as_a_type, unescapeLeadingUnderscores(name)); + return true; + } + } + return false; + } + + function checkResolvedBlockScopedVariable(result: Symbol, errorLocation: Node): void { + Debug.assert(!!(result.flags & SymbolFlags.BlockScopedVariable || result.flags & SymbolFlags.Class || result.flags & SymbolFlags.Enum)); + if (result.flags & (SymbolFlags.Function | SymbolFlags.FunctionScopedVariable | SymbolFlags.Assignment) && result.flags & SymbolFlags.Class) { + // constructor functions aren't block scoped + return; + } + // Block-scoped variables cannot be used before their definition + const declaration = result.declarations?.find( + d => isBlockOrCatchScoped(d) || isClassLike(d) || (d.kind === SyntaxKind.EnumDeclaration), + ); + + if (declaration === undefined) return Debug.fail("checkResolvedBlockScopedVariable could not find block-scoped declaration"); + + if (!(declaration.flags & NodeFlags.Ambient) && !isBlockScopedNameDeclaredBeforeUse(declaration, errorLocation)) { + let diagnosticMessage; + const declarationName = declarationNameToString(getNameOfDeclaration(declaration)); + if (result.flags & SymbolFlags.BlockScopedVariable) { + diagnosticMessage = error(errorLocation, Diagnostics.Block_scoped_variable_0_used_before_its_declaration, declarationName); + } + else if (result.flags & SymbolFlags.Class) { + diagnosticMessage = error(errorLocation, Diagnostics.Class_0_used_before_its_declaration, declarationName); + } + else if (result.flags & SymbolFlags.RegularEnum) { + diagnosticMessage = error(errorLocation, Diagnostics.Enum_0_used_before_its_declaration, declarationName); + } + else { + Debug.assert(!!(result.flags & SymbolFlags.ConstEnum)); + if (getIsolatedModules(compilerOptions)) { + diagnosticMessage = error(errorLocation, Diagnostics.Enum_0_used_before_its_declaration, declarationName); + } + } + + if (diagnosticMessage) { + addRelatedInfo(diagnosticMessage, createDiagnosticForNode(declaration, Diagnostics._0_is_declared_here, declarationName)); + } + } + } + + /* Starting from 'initial' node walk up the parent chain until 'stopAt' node is reached. + * If at any point current node is equal to 'parent' node - return true. + * If current node is an IIFE, continue walking up. + * Return false if 'stopAt' node is reached or isFunctionLike(current) === true. + */ + function isSameScopeDescendentOf(initial: Node, parent: Node | undefined, stopAt: Node): boolean { + return !!parent && !!findAncestor(initial, n => + n === parent + || (n === stopAt || isFunctionLike(n) && (!getImmediatelyInvokedFunctionExpression(n) || (getFunctionFlags(n) & FunctionFlags.AsyncGenerator)) ? "quit" : false)); + } + + function getAnyImportSyntax(node: Node): AnyImportOrJsDocImport | undefined { + switch (node.kind) { + case SyntaxKind.ImportEqualsDeclaration: + return node as ImportEqualsDeclaration; + case SyntaxKind.ImportClause: + return (node as ImportClause).parent; + case SyntaxKind.NamespaceImport: + return (node as NamespaceImport).parent.parent; + case SyntaxKind.ImportSpecifier: + return (node as ImportSpecifier).parent.parent.parent; + default: + return undefined; + } + } + + function getDeclarationOfAliasSymbol(symbol: Symbol): Declaration | undefined { + return symbol.declarations && findLast(symbol.declarations, isAliasSymbolDeclaration); + } + + /** + * An alias symbol is created by one of the following declarations: + * import = ... + * import from ... + * import * as from ... + * import { x as } from ... + * export { x as } from ... + * export * as ns from ... + * export = + * export default + * module.exports = + * {} + * {name: } + * const { x } = require ... + */ + function isAliasSymbolDeclaration(node: Node): boolean { + return node.kind === SyntaxKind.ImportEqualsDeclaration + || node.kind === SyntaxKind.NamespaceExportDeclaration + || node.kind === SyntaxKind.ImportClause && !!(node as ImportClause).name + || node.kind === SyntaxKind.NamespaceImport + || node.kind === SyntaxKind.NamespaceExport + || node.kind === SyntaxKind.ImportSpecifier + || node.kind === SyntaxKind.ExportSpecifier + || node.kind === SyntaxKind.ExportAssignment && exportAssignmentIsAlias(node as ExportAssignment) + || isBinaryExpression(node) && getAssignmentDeclarationKind(node) === AssignmentDeclarationKind.ModuleExports && exportAssignmentIsAlias(node) + || isAccessExpression(node) + && isBinaryExpression(node.parent) + && node.parent.left === node + && node.parent.operatorToken.kind === SyntaxKind.EqualsToken + && isAliasableOrJsExpression(node.parent.right) + || node.kind === SyntaxKind.ShorthandPropertyAssignment + || node.kind === SyntaxKind.PropertyAssignment && isAliasableOrJsExpression((node as PropertyAssignment).initializer) + || node.kind === SyntaxKind.VariableDeclaration && isVariableDeclarationInitializedToBareOrAccessedRequire(node) + || node.kind === SyntaxKind.BindingElement && isVariableDeclarationInitializedToBareOrAccessedRequire(node.parent.parent); + } + + function isAliasableOrJsExpression(e: Expression) { + return isAliasableExpression(e) || isFunctionExpression(e) && isJSConstructor(e); + } + + function getTargetOfImportEqualsDeclaration(node: ImportEqualsDeclaration | VariableDeclaration, dontResolveAlias: boolean): Symbol | undefined { + const commonJSPropertyAccess = getCommonJSPropertyAccess(node); + if (commonJSPropertyAccess) { + const name = (getLeftmostAccessExpression(commonJSPropertyAccess.expression) as CallExpression).arguments[0] as StringLiteral; + return isIdentifier(commonJSPropertyAccess.name) + ? resolveSymbol(getPropertyOfType(resolveExternalModuleTypeByLiteral(name), commonJSPropertyAccess.name.escapedText)) + : undefined; + } + if (isVariableDeclaration(node) || node.moduleReference.kind === SyntaxKind.ExternalModuleReference) { + const immediate = resolveExternalModuleName( + node, + getExternalModuleRequireArgument(node) || getExternalModuleImportEqualsDeclarationExpression(node), + ); + const resolved = resolveExternalModuleSymbol(immediate); + markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); + return resolved; + } + const resolved = getSymbolOfPartOfRightHandSideOfImportEquals(node.moduleReference, dontResolveAlias); + checkAndReportErrorForResolvingImportAliasToTypeOnlySymbol(node, resolved); + return resolved; + } + + function checkAndReportErrorForResolvingImportAliasToTypeOnlySymbol(node: ImportEqualsDeclaration, resolved: Symbol | undefined) { + if (markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false) && !node.isTypeOnly) { + const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(getSymbolOfDeclaration(node))!; + const isExport = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration; + const message = isExport + ? Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_exported_using_export_type + : Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_imported_using_import_type; + const relatedMessage = isExport + ? Diagnostics._0_was_exported_here + : Diagnostics._0_was_imported_here; + + // TODO: how to get name for export *? + const name = typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration ? "*" : moduleExportNameTextUnescaped(typeOnlyDeclaration.name); + addRelatedInfo(error(node.moduleReference, message), createDiagnosticForNode(typeOnlyDeclaration, relatedMessage, name)); + } + } + + function resolveExportByName(moduleSymbol: Symbol, name: __String, sourceNode: TypeOnlyCompatibleAliasDeclaration | undefined, dontResolveAlias: boolean) { + const exportValue = moduleSymbol.exports!.get(InternalSymbolName.ExportEquals); + const exportSymbol = exportValue + ? getPropertyOfType(getTypeOfSymbol(exportValue), name, /*skipObjectFunctionPropertyAugment*/ true) + : moduleSymbol.exports!.get(name); + const resolved = resolveSymbol(exportSymbol, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(sourceNode, exportSymbol, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function isSyntacticDefault(node: Node) { + return ((isExportAssignment(node) && !node.isExportEquals) + || hasSyntacticModifier(node, ModifierFlags.Default) + || isExportSpecifier(node) + || isNamespaceExport(node)); + } + + function getUsageModeForExpression(usage: Expression) { + return isStringLiteralLike(usage) ? host.getModeForUsageLocation(getSourceFileOfNode(usage), usage) : undefined; + } + + function isESMFormatImportImportingCommonjsFormatFile(usageMode: ResolutionMode, targetMode: ResolutionMode) { + return usageMode === ModuleKind.ESNext && targetMode === ModuleKind.CommonJS; + } + + function isOnlyImportedAsDefault(usage: Expression) { + const usageMode = getUsageModeForExpression(usage); + return usageMode === ModuleKind.ESNext && endsWith((usage as StringLiteralLike).text, Extension.Json); + } + + function canHaveSyntheticDefault(file: SourceFile | undefined, moduleSymbol: Symbol, dontResolveAlias: boolean, usage: Expression) { + const usageMode = file && getUsageModeForExpression(usage); + if (file && usageMode !== undefined && ModuleKind.Node16 <= moduleKind && moduleKind <= ModuleKind.NodeNext) { + const result = isESMFormatImportImportingCommonjsFormatFile(usageMode, file.impliedNodeFormat); + if (usageMode === ModuleKind.ESNext || result) { + return result; + } + // fallthrough on cjs usages so we imply defaults for interop'd imports, too + } + if (!allowSyntheticDefaultImports) { + return false; + } + // Declaration files (and ambient modules) + if (!file || file.isDeclarationFile) { + // Definitely cannot have a synthetic default if they have a syntactic default member specified + const defaultExportSymbol = resolveExportByName(moduleSymbol, InternalSymbolName.Default, /*sourceNode*/ undefined, /*dontResolveAlias*/ true); // Dont resolve alias because we want the immediately exported symbol's declaration + if (defaultExportSymbol && some(defaultExportSymbol.declarations, isSyntacticDefault)) { + return false; + } + // It _might_ still be incorrect to assume there is no __esModule marker on the import at runtime, even if there is no `default` member + // So we check a bit more, + if (resolveExportByName(moduleSymbol, escapeLeadingUnderscores("__esModule"), /*sourceNode*/ undefined, dontResolveAlias)) { + // If there is an `__esModule` specified in the declaration (meaning someone explicitly added it or wrote it in their code), + // it definitely is a module and does not have a synthetic default + return false; + } + // There are _many_ declaration files not written with esmodules in mind that still get compiled into a format with __esModule set + // Meaning there may be no default at runtime - however to be on the permissive side, we allow access to a synthetic default member + // as there is no marker to indicate if the accompanying JS has `__esModule` or not, or is even native esm + return true; + } + // TypeScript files never have a synthetic default (as they are always emitted with an __esModule marker) _unless_ they contain an export= statement + if (!isSourceFileJS(file)) { + return hasExportAssignmentSymbol(moduleSymbol); + } + // JS files have a synthetic default if they do not contain ES2015+ module syntax (export = is not valid in js) _and_ do not have an __esModule marker + return typeof file.externalModuleIndicator !== "object" && !resolveExportByName(moduleSymbol, escapeLeadingUnderscores("__esModule"), /*sourceNode*/ undefined, dontResolveAlias); + } + + function getTargetOfImportClause(node: ImportClause, dontResolveAlias: boolean): Symbol | undefined { + const moduleSymbol = resolveExternalModuleName(node, node.parent.moduleSpecifier); + if (moduleSymbol) { + return getTargetofModuleDefault(moduleSymbol, node, dontResolveAlias); + } + } + + function getTargetofModuleDefault(moduleSymbol: Symbol, node: ImportClause | ImportOrExportSpecifier, dontResolveAlias: boolean) { + let exportDefaultSymbol: Symbol | undefined; + if (isShorthandAmbientModuleSymbol(moduleSymbol)) { + exportDefaultSymbol = moduleSymbol; + } + else { + exportDefaultSymbol = resolveExportByName(moduleSymbol, InternalSymbolName.Default, node, dontResolveAlias); + } + + const file = moduleSymbol.declarations?.find(isSourceFile); + const specifier = getModuleSpecifierForImportOrExport(node); + if (!specifier) { + return exportDefaultSymbol; + } + const hasDefaultOnly = isOnlyImportedAsDefault(specifier); + const hasSyntheticDefault = canHaveSyntheticDefault(file, moduleSymbol, dontResolveAlias, specifier); + if (!exportDefaultSymbol && !hasSyntheticDefault && !hasDefaultOnly) { + if (hasExportAssignmentSymbol(moduleSymbol) && !allowSyntheticDefaultImports) { + const compilerOptionName = moduleKind >= ModuleKind.ES2015 ? "allowSyntheticDefaultImports" : "esModuleInterop"; + const exportEqualsSymbol = moduleSymbol.exports!.get(InternalSymbolName.ExportEquals); + const exportAssignment = exportEqualsSymbol!.valueDeclaration; + const err = error(node.name, Diagnostics.Module_0_can_only_be_default_imported_using_the_1_flag, symbolToString(moduleSymbol), compilerOptionName); + + if (exportAssignment) { + addRelatedInfo( + err, + createDiagnosticForNode( + exportAssignment, + Diagnostics.This_module_is_declared_with_export_and_can_only_be_used_with_a_default_import_when_using_the_0_flag, + compilerOptionName, + ), + ); + } + } + else if (isImportClause(node)) { + reportNonDefaultExport(moduleSymbol, node); + } + else { + errorNoModuleMemberSymbol(moduleSymbol, moduleSymbol, node, isImportOrExportSpecifier(node) && node.propertyName || node.name); + } + } + else if (hasSyntheticDefault || hasDefaultOnly) { + // per emit behavior, a synthetic default overrides a "real" .default member if `__esModule` is not present + const resolved = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias) || resolveSymbol(moduleSymbol, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, moduleSymbol, resolved, /*overwriteEmpty*/ false); + return resolved; + } + markSymbolOfAliasDeclarationIfTypeOnly(node, exportDefaultSymbol, /*finalTarget*/ undefined, /*overwriteEmpty*/ false); + return exportDefaultSymbol; + } + + function getModuleSpecifierForImportOrExport(node: ImportEqualsDeclaration | ImportClause | NamespaceImport | ImportOrExportSpecifier): Expression | undefined { + switch (node.kind) { + case SyntaxKind.ImportClause: + return node.parent.moduleSpecifier; + case SyntaxKind.ImportEqualsDeclaration: + return isExternalModuleReference(node.moduleReference) ? node.moduleReference.expression : undefined; + case SyntaxKind.NamespaceImport: + return node.parent.parent.moduleSpecifier; + case SyntaxKind.ImportSpecifier: + return node.parent.parent.parent.moduleSpecifier; + case SyntaxKind.ExportSpecifier: + return node.parent.parent.moduleSpecifier; + default: + return Debug.assertNever(node); + } + } + + function reportNonDefaultExport(moduleSymbol: Symbol, node: ImportClause) { + if (moduleSymbol.exports?.has(node.symbol.escapedName)) { + error( + node.name, + Diagnostics.Module_0_has_no_default_export_Did_you_mean_to_use_import_1_from_0_instead, + symbolToString(moduleSymbol), + symbolToString(node.symbol), + ); + } + else { + const diagnostic = error(node.name, Diagnostics.Module_0_has_no_default_export, symbolToString(moduleSymbol)); + const exportStar = moduleSymbol.exports?.get(InternalSymbolName.ExportStar); + if (exportStar) { + const defaultExport = exportStar.declarations?.find(decl => + !!( + isExportDeclaration(decl) && decl.moduleSpecifier && + resolveExternalModuleName(decl, decl.moduleSpecifier)?.exports?.has(InternalSymbolName.Default) + ) + ); + if (defaultExport) { + addRelatedInfo(diagnostic, createDiagnosticForNode(defaultExport, Diagnostics.export_Asterisk_does_not_re_export_a_default)); + } + } + } + } + + function getTargetOfNamespaceImport(node: NamespaceImport, dontResolveAlias: boolean): Symbol | undefined { + const moduleSpecifier = node.parent.parent.moduleSpecifier; + const immediate = resolveExternalModuleName(node, moduleSpecifier); + const resolved = resolveESModuleSymbol(immediate, moduleSpecifier, dontResolveAlias, /*suppressInteropError*/ false); + markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getTargetOfNamespaceExport(node: NamespaceExport, dontResolveAlias: boolean): Symbol | undefined { + const moduleSpecifier = node.parent.moduleSpecifier; + const immediate = moduleSpecifier && resolveExternalModuleName(node, moduleSpecifier); + const resolved = moduleSpecifier && resolveESModuleSymbol(immediate, moduleSpecifier, dontResolveAlias, /*suppressInteropError*/ false); + markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + // This function creates a synthetic symbol that combines the value side of one symbol with the + // type/namespace side of another symbol. Consider this example: + // + // declare module graphics { + // interface Point { + // x: number; + // y: number; + // } + // } + // declare var graphics: { + // Point: new (x: number, y: number) => graphics.Point; + // } + // declare module "graphics" { + // export = graphics; + // } + // + // An 'import { Point } from "graphics"' needs to create a symbol that combines the value side 'Point' + // property with the type/namespace side interface 'Point'. + function combineValueAndTypeSymbols(valueSymbol: Symbol, typeSymbol: Symbol): Symbol { + if (valueSymbol === unknownSymbol && typeSymbol === unknownSymbol) { + return unknownSymbol; + } + if (valueSymbol.flags & (SymbolFlags.Type | SymbolFlags.Namespace)) { + return valueSymbol; + } + const result = createSymbol(valueSymbol.flags | typeSymbol.flags, valueSymbol.escapedName); + Debug.assert(valueSymbol.declarations || typeSymbol.declarations); + result.declarations = deduplicate(concatenate(valueSymbol.declarations!, typeSymbol.declarations), equateValues); + result.parent = valueSymbol.parent || typeSymbol.parent; + if (valueSymbol.valueDeclaration) result.valueDeclaration = valueSymbol.valueDeclaration; + if (typeSymbol.members) result.members = new Map(typeSymbol.members); + if (valueSymbol.exports) result.exports = new Map(valueSymbol.exports); + return result; + } + + function getExportOfModule(symbol: Symbol, nameText: __String, specifier: Declaration, dontResolveAlias: boolean): Symbol | undefined { + if (symbol.flags & SymbolFlags.Module) { + const exportSymbol = getExportsOfSymbol(symbol).get(nameText); + const resolved = resolveSymbol(exportSymbol, dontResolveAlias); + const exportStarDeclaration = getSymbolLinks(symbol).typeOnlyExportStarMap?.get(nameText); + markSymbolOfAliasDeclarationIfTypeOnly(specifier, exportSymbol, resolved, /*overwriteEmpty*/ false, exportStarDeclaration, nameText); + return resolved; + } + } + + function getPropertyOfVariable(symbol: Symbol, name: __String): Symbol | undefined { + if (symbol.flags & SymbolFlags.Variable) { + const typeAnnotation = (symbol.valueDeclaration as VariableDeclaration).type; + if (typeAnnotation) { + return resolveSymbol(getPropertyOfType(getTypeFromTypeNode(typeAnnotation), name)); + } + } + } + + function getExternalModuleMember(node: ImportDeclaration | ExportDeclaration | VariableDeclaration | JSDocImportTag, specifier: ImportOrExportSpecifier | BindingElement | PropertyAccessExpression, dontResolveAlias = false): Symbol | undefined { + const moduleSpecifier = getExternalModuleRequireArgument(node) || (node as ImportDeclaration | ExportDeclaration | JSDocImportTag).moduleSpecifier!; + const moduleSymbol = resolveExternalModuleName(node, moduleSpecifier)!; // TODO: GH#18217 + const name = !isPropertyAccessExpression(specifier) && specifier.propertyName || specifier.name; + if (!isIdentifier(name) && name.kind !== SyntaxKind.StringLiteral) { + return undefined; + } + const nameText = moduleExportNameTextEscaped(name); + const suppressInteropError = nameText === InternalSymbolName.Default && allowSyntheticDefaultImports; + const targetSymbol = resolveESModuleSymbol(moduleSymbol, moduleSpecifier, /*dontResolveAlias*/ false, suppressInteropError); + if (targetSymbol) { + // Note: The empty string is a valid module export name: + // + // import { "" as foo } from "./foo"; + // export { foo as "" }; + // + if (nameText || name.kind === SyntaxKind.StringLiteral) { + if (isShorthandAmbientModuleSymbol(moduleSymbol)) { + return moduleSymbol; + } + + let symbolFromVariable: Symbol | undefined; + // First check if module was specified with "export=". If so, get the member from the resolved type + if (moduleSymbol && moduleSymbol.exports && moduleSymbol.exports.get(InternalSymbolName.ExportEquals)) { + symbolFromVariable = getPropertyOfType(getTypeOfSymbol(targetSymbol), nameText, /*skipObjectFunctionPropertyAugment*/ true); + } + else { + symbolFromVariable = getPropertyOfVariable(targetSymbol, nameText); + } + // if symbolFromVariable is export - get its final target + symbolFromVariable = resolveSymbol(symbolFromVariable, dontResolveAlias); + + let symbolFromModule = getExportOfModule(targetSymbol, nameText, specifier, dontResolveAlias); + if (symbolFromModule === undefined && nameText === InternalSymbolName.Default) { + const file = moduleSymbol.declarations?.find(isSourceFile); + if (isOnlyImportedAsDefault(moduleSpecifier) || canHaveSyntheticDefault(file, moduleSymbol, dontResolveAlias, moduleSpecifier)) { + symbolFromModule = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias) || resolveSymbol(moduleSymbol, dontResolveAlias); + } + } + + const symbol = symbolFromModule && symbolFromVariable && symbolFromModule !== symbolFromVariable ? + combineValueAndTypeSymbols(symbolFromVariable, symbolFromModule) : + symbolFromModule || symbolFromVariable; + if (!symbol) { + errorNoModuleMemberSymbol(moduleSymbol, targetSymbol, node, name); + } + return symbol; + } + } + } + + function errorNoModuleMemberSymbol(moduleSymbol: Symbol, targetSymbol: Symbol, node: Node, name: ModuleExportName) { + const moduleName = getFullyQualifiedName(moduleSymbol, node); + const declarationName = declarationNameToString(name); + const suggestion = isIdentifier(name) ? getSuggestedSymbolForNonexistentModule(name, targetSymbol) : undefined; + if (suggestion !== undefined) { + const suggestionName = symbolToString(suggestion); + const diagnostic = error(name, Diagnostics._0_has_no_exported_member_named_1_Did_you_mean_2, moduleName, declarationName, suggestionName); + if (suggestion.valueDeclaration) { + addRelatedInfo(diagnostic, createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestionName)); + } + } + else { + if (moduleSymbol.exports?.has(InternalSymbolName.Default)) { + error( + name, + Diagnostics.Module_0_has_no_exported_member_1_Did_you_mean_to_use_import_1_from_0_instead, + moduleName, + declarationName, + ); + } + else { + reportNonExportedMember(node, name, declarationName, moduleSymbol, moduleName); + } + } + } + + function reportNonExportedMember(node: Node, name: ModuleExportName, declarationName: string, moduleSymbol: Symbol, moduleName: string): void { + const localSymbol = tryCast(moduleSymbol.valueDeclaration, canHaveLocals)?.locals?.get(moduleExportNameTextEscaped(name)); + const exports = moduleSymbol.exports; + if (localSymbol) { + const exportedEqualsSymbol = exports?.get(InternalSymbolName.ExportEquals); + if (exportedEqualsSymbol) { + getSymbolIfSameReference(exportedEqualsSymbol, localSymbol) ? reportInvalidImportEqualsExportMember(node, name, declarationName, moduleName) : + error(name, Diagnostics.Module_0_has_no_exported_member_1, moduleName, declarationName); + } + else { + const exportedSymbol = exports ? find(symbolsToArray(exports), symbol => !!getSymbolIfSameReference(symbol, localSymbol)) : undefined; + const diagnostic = exportedSymbol ? error(name, Diagnostics.Module_0_declares_1_locally_but_it_is_exported_as_2, moduleName, declarationName, symbolToString(exportedSymbol)) : + error(name, Diagnostics.Module_0_declares_1_locally_but_it_is_not_exported, moduleName, declarationName); + if (localSymbol.declarations) { + addRelatedInfo(diagnostic, ...map(localSymbol.declarations, (decl, index) => createDiagnosticForNode(decl, index === 0 ? Diagnostics._0_is_declared_here : Diagnostics.and_here, declarationName))); + } + } + } + else { + error(name, Diagnostics.Module_0_has_no_exported_member_1, moduleName, declarationName); + } + } + + function reportInvalidImportEqualsExportMember(node: Node, name: ModuleExportName, declarationName: string, moduleName: string) { + if (moduleKind >= ModuleKind.ES2015) { + const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_a_default_import : + Diagnostics._0_can_only_be_imported_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; + error(name, message, declarationName); + } + else { + if (isInJSFile(node)) { + const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_a_require_call_or_by_using_a_default_import : + Diagnostics._0_can_only_be_imported_by_using_a_require_call_or_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; + error(name, message, declarationName); + } + else { + const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_import_1_require_2_or_a_default_import : + Diagnostics._0_can_only_be_imported_by_using_import_1_require_2_or_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; + error(name, message, declarationName, declarationName, moduleName); + } + } + } + + function getTargetOfImportSpecifier(node: ImportSpecifier | BindingElement, dontResolveAlias: boolean): Symbol | undefined { + if (isImportSpecifier(node) && moduleExportNameIsDefault(node.propertyName || node.name)) { + const specifier = getModuleSpecifierForImportOrExport(node); + const moduleSymbol = specifier && resolveExternalModuleName(node, specifier); + if (moduleSymbol) { + return getTargetofModuleDefault(moduleSymbol, node, dontResolveAlias); + } + } + const root = isBindingElement(node) ? getRootDeclaration(node) as VariableDeclaration : node.parent.parent.parent; + const commonJSPropertyAccess = getCommonJSPropertyAccess(root); + const resolved = getExternalModuleMember(root, commonJSPropertyAccess || node, dontResolveAlias); + const name = node.propertyName || node.name; + if (commonJSPropertyAccess && resolved && isIdentifier(name)) { + return resolveSymbol(getPropertyOfType(getTypeOfSymbol(resolved), name.escapedText), dontResolveAlias); + } + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getCommonJSPropertyAccess(node: Node) { + if (isVariableDeclaration(node) && node.initializer && isPropertyAccessExpression(node.initializer)) { + return node.initializer; + } + } + + function getTargetOfNamespaceExportDeclaration(node: NamespaceExportDeclaration, dontResolveAlias: boolean): Symbol | undefined { + if (canHaveSymbol(node.parent)) { + const resolved = resolveExternalModuleSymbol(node.parent.symbol, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + } + + function getTargetOfExportSpecifier(node: ExportSpecifier, meaning: SymbolFlags, dontResolveAlias?: boolean) { + const name = node.propertyName || node.name; + if (moduleExportNameIsDefault(name)) { + const specifier = getModuleSpecifierForImportOrExport(node); + const moduleSymbol = specifier && resolveExternalModuleName(node, specifier); + if (moduleSymbol) { + return getTargetofModuleDefault(moduleSymbol, node, !!dontResolveAlias); + } + } + const resolved = node.parent.parent.moduleSpecifier ? + getExternalModuleMember(node.parent.parent, node, dontResolveAlias) : + name.kind === SyntaxKind.StringLiteral ? undefined : // Skip for invalid syntax like this: export { "x" } + resolveEntityName(name, meaning, /*ignoreErrors*/ false, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getTargetOfExportAssignment(node: ExportAssignment | BinaryExpression, dontResolveAlias: boolean): Symbol | undefined { + const expression = isExportAssignment(node) ? node.expression : node.right; + const resolved = getTargetOfAliasLikeExpression(expression, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getTargetOfAliasLikeExpression(expression: Expression, dontResolveAlias: boolean) { + if (isClassExpression(expression)) { + return checkExpressionCached(expression).symbol; + } + if (!isEntityName(expression) && !isEntityNameExpression(expression)) { + return undefined; + } + const aliasLike = resolveEntityName(expression, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ true, dontResolveAlias); + if (aliasLike) { + return aliasLike; + } + checkExpressionCached(expression); + return getNodeLinks(expression).resolvedSymbol; + } + + function getTargetOfAccessExpression(node: AccessExpression, dontRecursivelyResolve: boolean): Symbol | undefined { + if (!(isBinaryExpression(node.parent) && node.parent.left === node && node.parent.operatorToken.kind === SyntaxKind.EqualsToken)) { + return undefined; + } + + return getTargetOfAliasLikeExpression(node.parent.right, dontRecursivelyResolve); + } + + function getTargetOfAliasDeclaration(node: Declaration, dontRecursivelyResolve = false): Symbol | undefined { + switch (node.kind) { + case SyntaxKind.ImportEqualsDeclaration: + case SyntaxKind.VariableDeclaration: + return getTargetOfImportEqualsDeclaration(node as ImportEqualsDeclaration | VariableDeclaration, dontRecursivelyResolve); + case SyntaxKind.ImportClause: + return getTargetOfImportClause(node as ImportClause, dontRecursivelyResolve); + case SyntaxKind.NamespaceImport: + return getTargetOfNamespaceImport(node as NamespaceImport, dontRecursivelyResolve); + case SyntaxKind.NamespaceExport: + return getTargetOfNamespaceExport(node as NamespaceExport, dontRecursivelyResolve); + case SyntaxKind.ImportSpecifier: + case SyntaxKind.BindingElement: + return getTargetOfImportSpecifier(node as ImportSpecifier | BindingElement, dontRecursivelyResolve); + case SyntaxKind.ExportSpecifier: + return getTargetOfExportSpecifier(node as ExportSpecifier, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, dontRecursivelyResolve); + case SyntaxKind.ExportAssignment: + case SyntaxKind.BinaryExpression: + return getTargetOfExportAssignment(node as ExportAssignment | BinaryExpression, dontRecursivelyResolve); + case SyntaxKind.NamespaceExportDeclaration: + return getTargetOfNamespaceExportDeclaration(node as NamespaceExportDeclaration, dontRecursivelyResolve); + case SyntaxKind.ShorthandPropertyAssignment: + return resolveEntityName((node as ShorthandPropertyAssignment).name, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ true, dontRecursivelyResolve); + case SyntaxKind.PropertyAssignment: + return getTargetOfAliasLikeExpression((node as PropertyAssignment).initializer, dontRecursivelyResolve); + case SyntaxKind.ElementAccessExpression: + case SyntaxKind.PropertyAccessExpression: + return getTargetOfAccessExpression(node as AccessExpression, dontRecursivelyResolve); + default: + return Debug.fail(); + } + } + + /** + * Indicates that a symbol is an alias that does not merge with a local declaration. + * OR Is a JSContainer which may merge an alias with a local declaration + */ + function isNonLocalAlias(symbol: Symbol | undefined, excludes = SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace): symbol is Symbol { + if (!symbol) return false; + return (symbol.flags & (SymbolFlags.Alias | excludes)) === SymbolFlags.Alias || !!(symbol.flags & SymbolFlags.Alias && symbol.flags & SymbolFlags.Assignment); + } + + function resolveSymbol(symbol: Symbol, dontResolveAlias?: boolean): Symbol; + function resolveSymbol(symbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined; + function resolveSymbol(symbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined { + return !dontResolveAlias && isNonLocalAlias(symbol) ? resolveAlias(symbol) : symbol; + } + + function resolveAlias(symbol: Symbol): Symbol { + Debug.assert((symbol.flags & SymbolFlags.Alias) !== 0, "Should only get Alias here."); + const links = getSymbolLinks(symbol); + if (!links.aliasTarget) { + links.aliasTarget = resolvingSymbol; + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + const target = getTargetOfAliasDeclaration(node); + if (links.aliasTarget === resolvingSymbol) { + links.aliasTarget = target || unknownSymbol; + } + else { + error(node, Diagnostics.Circular_definition_of_import_alias_0, symbolToString(symbol)); + } + } + else if (links.aliasTarget === resolvingSymbol) { + links.aliasTarget = unknownSymbol; + } + return links.aliasTarget; + } + + function tryResolveAlias(symbol: Symbol): Symbol | undefined { + const links = getSymbolLinks(symbol); + if (links.aliasTarget !== resolvingSymbol) { + return resolveAlias(symbol); + } + + return undefined; + } + + /** + * Gets combined flags of a `symbol` and all alias targets it resolves to. `resolveAlias` + * is typically recursive over chains of aliases, but stops mid-chain if an alias is merged + * with another exported symbol, e.g. + * ```ts + * // a.ts + * export const a = 0; + * // b.ts + * export { a } from "./a"; + * export type a = number; + * // c.ts + * import { a } from "./b"; + * ``` + * Calling `resolveAlias` on the `a` in c.ts would stop at the merged symbol exported + * from b.ts, even though there is still more alias to resolve. Consequently, if we were + * trying to determine if the `a` in c.ts has a value meaning, looking at the flags on + * the local symbol and on the symbol returned by `resolveAlias` is not enough. + * @returns SymbolFlags.All if `symbol` is an alias that ultimately resolves to `unknown`; + * combined flags of all alias targets otherwise. + */ + function getSymbolFlags(symbol: Symbol, excludeTypeOnlyMeanings?: boolean, excludeLocalMeanings?: boolean): SymbolFlags { + const typeOnlyDeclaration = excludeTypeOnlyMeanings && getTypeOnlyAliasDeclaration(symbol); + const typeOnlyDeclarationIsExportStar = typeOnlyDeclaration && isExportDeclaration(typeOnlyDeclaration); + const typeOnlyResolution = typeOnlyDeclaration && ( + typeOnlyDeclarationIsExportStar + ? resolveExternalModuleName(typeOnlyDeclaration.moduleSpecifier, typeOnlyDeclaration.moduleSpecifier, /*ignoreErrors*/ true) + : resolveAlias(typeOnlyDeclaration.symbol) + ); + const typeOnlyExportStarTargets = typeOnlyDeclarationIsExportStar && typeOnlyResolution ? getExportsOfModule(typeOnlyResolution) : undefined; + let flags = excludeLocalMeanings ? SymbolFlags.None : symbol.flags; + let seenSymbols; + while (symbol.flags & SymbolFlags.Alias) { + const target = getExportSymbolOfValueSymbolIfExported(resolveAlias(symbol)); + if ( + !typeOnlyDeclarationIsExportStar && target === typeOnlyResolution || + typeOnlyExportStarTargets?.get(target.escapedName) === target + ) { + break; + } + if (target === unknownSymbol) { + return SymbolFlags.All; + } + + // Optimizations - try to avoid creating or adding to + // `seenSymbols` if possible + if (target === symbol || seenSymbols?.has(target)) { + break; + } + if (target.flags & SymbolFlags.Alias) { + if (seenSymbols) { + seenSymbols.add(target); + } + else { + seenSymbols = new Set([symbol, target]); + } + } + flags |= target.flags; + symbol = target; + } + return flags; + } + + /** + * Marks a symbol as type-only if its declaration is syntactically type-only. + * If it is not itself marked type-only, but resolves to a type-only alias + * somewhere in its resolution chain, save a reference to the type-only alias declaration + * so the alias _not_ marked type-only can be identified as _transitively_ type-only. + * + * This function is called on each alias declaration that could be type-only or resolve to + * another type-only alias during `resolveAlias`, so that later, when an alias is used in a + * JS-emitting expression, we can quickly determine if that symbol is effectively type-only + * and issue an error if so. + * + * @param aliasDeclaration The alias declaration not marked as type-only + * @param immediateTarget The symbol to which the alias declaration immediately resolves + * @param finalTarget The symbol to which the alias declaration ultimately resolves + * @param overwriteEmpty Checks `resolvesToSymbol` for type-only declarations even if `aliasDeclaration` + * has already been marked as not resolving to a type-only alias. Used when recursively resolving qualified + * names of import aliases, e.g. `import C = a.b.C`. If namespace `a` is not found to be type-only, the + * import declaration will initially be marked as not resolving to a type-only symbol. But, namespace `b` + * must still be checked for a type-only marker, overwriting the previous negative result if found. + */ + function markSymbolOfAliasDeclarationIfTypeOnly( + aliasDeclaration: Declaration | undefined, + immediateTarget: Symbol | undefined, + finalTarget: Symbol | undefined, + overwriteEmpty: boolean, + exportStarDeclaration?: ExportDeclaration & { readonly isTypeOnly: true; readonly moduleSpecifier: Expression; }, + exportStarName?: __String, + ): boolean { + if (!aliasDeclaration || isPropertyAccessExpression(aliasDeclaration)) return false; + + // If the declaration itself is type-only, mark it and return. + // No need to check what it resolves to. + const sourceSymbol = getSymbolOfDeclaration(aliasDeclaration); + if (isTypeOnlyImportOrExportDeclaration(aliasDeclaration)) { + const links = getSymbolLinks(sourceSymbol); + links.typeOnlyDeclaration = aliasDeclaration; + return true; + } + if (exportStarDeclaration) { + const links = getSymbolLinks(sourceSymbol); + links.typeOnlyDeclaration = exportStarDeclaration; + if (sourceSymbol.escapedName !== exportStarName) { + links.typeOnlyExportStarName = exportStarName; + } + return true; + } + + const links = getSymbolLinks(sourceSymbol); + return markSymbolOfAliasDeclarationIfTypeOnlyWorker(links, immediateTarget, overwriteEmpty) + || markSymbolOfAliasDeclarationIfTypeOnlyWorker(links, finalTarget, overwriteEmpty); + } + + function markSymbolOfAliasDeclarationIfTypeOnlyWorker(aliasDeclarationLinks: SymbolLinks, target: Symbol | undefined, overwriteEmpty: boolean): boolean { + if (target && (aliasDeclarationLinks.typeOnlyDeclaration === undefined || overwriteEmpty && aliasDeclarationLinks.typeOnlyDeclaration === false)) { + const exportSymbol = target.exports?.get(InternalSymbolName.ExportEquals) ?? target; + const typeOnly = exportSymbol.declarations && find(exportSymbol.declarations, isTypeOnlyImportOrExportDeclaration); + aliasDeclarationLinks.typeOnlyDeclaration = typeOnly ?? getSymbolLinks(exportSymbol).typeOnlyDeclaration ?? false; + } + return !!aliasDeclarationLinks.typeOnlyDeclaration; + } + + /** Indicates that a symbol directly or indirectly resolves to a type-only import or export. */ + function getTypeOnlyAliasDeclaration(symbol: Symbol, include?: SymbolFlags): TypeOnlyAliasDeclaration | undefined { + if (!(symbol.flags & SymbolFlags.Alias)) { + return undefined; + } + const links = getSymbolLinks(symbol); + if (links.typeOnlyDeclaration === undefined) { + // We need to set a WIP value here to prevent reentrancy during `getImmediateAliasedSymbol` which, paradoxically, can depend on this + links.typeOnlyDeclaration = false; + const resolved = resolveSymbol(symbol); // do this before the `resolveImmediate` below, as it uses a different circularity cache and we might hide a circularity error if we blindly get the immediate alias first + // While usually the alias will have been marked during the pass by the full typecheck, we may still need to calculate the alias declaration now + markSymbolOfAliasDeclarationIfTypeOnly(symbol.declarations?.[0], getDeclarationOfAliasSymbol(symbol) && getImmediateAliasedSymbol(symbol), resolved, /*overwriteEmpty*/ true); + } + if (include === undefined) { + return links.typeOnlyDeclaration || undefined; + } + if (links.typeOnlyDeclaration) { + const resolved = links.typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration + ? resolveSymbol(getExportsOfModule(links.typeOnlyDeclaration.symbol.parent!).get(links.typeOnlyExportStarName || symbol.escapedName))! + : resolveAlias(links.typeOnlyDeclaration.symbol); + return getSymbolFlags(resolved) & include ? links.typeOnlyDeclaration : undefined; + } + return undefined; + } + + // This function is only for imports with entity names + function getSymbolOfPartOfRightHandSideOfImportEquals(entityName: EntityName, dontResolveAlias?: boolean): Symbol | undefined { + // There are three things we might try to look for. In the following examples, + // the search term is enclosed in |...|: + // + // import a = |b|; // Namespace + // import a = |b.c|; // Value, type, namespace + // import a = |b.c|.d; // Namespace + if (entityName.kind === SyntaxKind.Identifier && isRightSideOfQualifiedNameOrPropertyAccess(entityName)) { + entityName = entityName.parent as QualifiedName; + } + // Check for case 1 and 3 in the above example + if (entityName.kind === SyntaxKind.Identifier || entityName.parent.kind === SyntaxKind.QualifiedName) { + return resolveEntityName(entityName, SymbolFlags.Namespace, /*ignoreErrors*/ false, dontResolveAlias); + } + else { + // Case 2 in above example + // entityName.kind could be a QualifiedName or a Missing identifier + Debug.assert(entityName.parent.kind === SyntaxKind.ImportEqualsDeclaration); + return resolveEntityName(entityName, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ false, dontResolveAlias); + } + } + + function getFullyQualifiedName(symbol: Symbol, containingLocation?: Node): string { + return symbol.parent ? getFullyQualifiedName(symbol.parent, containingLocation) + "." + symbolToString(symbol) : symbolToString(symbol, containingLocation, /*meaning*/ undefined, SymbolFormatFlags.DoNotIncludeSymbolChain | SymbolFormatFlags.AllowAnyNodeKind); + } + + function getContainingQualifiedNameNode(node: QualifiedName) { + while (isQualifiedName(node.parent)) { + node = node.parent; + } + return node; + } + + function tryGetQualifiedNameAsValue(node: QualifiedName) { + let left: Identifier | QualifiedName = getFirstIdentifier(node); + let symbol = resolveName(left, left, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (!symbol) { + return undefined; + } + while (isQualifiedName(left.parent)) { + const type = getTypeOfSymbol(symbol); + symbol = getPropertyOfType(type, left.parent.right.escapedText); + if (!symbol) { + return undefined; + } + left = left.parent; + } + return symbol; + } + + /** + * Resolves a qualified name and any involved aliases. + */ + function resolveEntityName(name: EntityNameOrEntityNameExpression, meaning: SymbolFlags, ignoreErrors?: boolean, dontResolveAlias?: boolean, location?: Node): Symbol | undefined { + if (nodeIsMissing(name)) { + return undefined; + } + + const namespaceMeaning = SymbolFlags.Namespace | (isInJSFile(name) ? meaning & SymbolFlags.Value : 0); + let symbol: Symbol | undefined; + if (name.kind === SyntaxKind.Identifier) { + const message = meaning === namespaceMeaning || nodeIsSynthesized(name) ? Diagnostics.Cannot_find_namespace_0 : getCannotFindNameDiagnosticForName(getFirstIdentifier(name)); + const symbolFromJSPrototype = isInJSFile(name) && !nodeIsSynthesized(name) ? resolveEntityNameFromAssignmentDeclaration(name, meaning) : undefined; + symbol = getMergedSymbol(resolveName(location || name, name, meaning, ignoreErrors || symbolFromJSPrototype ? undefined : message, /*isUse*/ true, /*excludeGlobals*/ false)); + if (!symbol) { + return getMergedSymbol(symbolFromJSPrototype); + } + } + else if (name.kind === SyntaxKind.QualifiedName || name.kind === SyntaxKind.PropertyAccessExpression) { + const left = name.kind === SyntaxKind.QualifiedName ? name.left : name.expression; + const right = name.kind === SyntaxKind.QualifiedName ? name.right : name.name; + let namespace = resolveEntityName(left, namespaceMeaning, ignoreErrors, /*dontResolveAlias*/ false, location); + if (!namespace || nodeIsMissing(right)) { + return undefined; + } + else if (namespace === unknownSymbol) { + return namespace; + } + if ( + namespace.valueDeclaration && + isInJSFile(namespace.valueDeclaration) && + getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Bundler && + isVariableDeclaration(namespace.valueDeclaration) && + namespace.valueDeclaration.initializer && + isCommonJsRequire(namespace.valueDeclaration.initializer) + ) { + const moduleName = (namespace.valueDeclaration.initializer as CallExpression).arguments[0] as StringLiteral; + const moduleSym = resolveExternalModuleName(moduleName, moduleName); + if (moduleSym) { + const resolvedModuleSymbol = resolveExternalModuleSymbol(moduleSym); + if (resolvedModuleSymbol) { + namespace = resolvedModuleSymbol; + } + } + } + symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(namespace), right.escapedText, meaning)); + if (!symbol && (namespace.flags & SymbolFlags.Alias)) { + // `namespace` can be resolved further if there was a symbol merge with a re-export + symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(resolveAlias(namespace)), right.escapedText, meaning)); + } + if (!symbol) { + if (!ignoreErrors) { + const namespaceName = getFullyQualifiedName(namespace); + const declarationName = declarationNameToString(right); + const suggestionForNonexistentModule = getSuggestedSymbolForNonexistentModule(right, namespace); + if (suggestionForNonexistentModule) { + error(right, Diagnostics._0_has_no_exported_member_named_1_Did_you_mean_2, namespaceName, declarationName, symbolToString(suggestionForNonexistentModule)); + return undefined; + } + + const containingQualifiedName = isQualifiedName(name) && getContainingQualifiedNameNode(name); + const canSuggestTypeof = globalObjectType // <-- can't pull on types if global types aren't initialized yet + && (meaning & SymbolFlags.Type) + && containingQualifiedName + && !isTypeOfExpression(containingQualifiedName.parent) + && tryGetQualifiedNameAsValue(containingQualifiedName); + if (canSuggestTypeof) { + error( + containingQualifiedName, + Diagnostics._0_refers_to_a_value_but_is_being_used_as_a_type_here_Did_you_mean_typeof_0, + entityNameToString(containingQualifiedName), + ); + return undefined; + } + + if (meaning & SymbolFlags.Namespace && isQualifiedName(name.parent)) { + const exportedTypeSymbol = getMergedSymbol(getSymbol(getExportsOfSymbol(namespace), right.escapedText, SymbolFlags.Type)); + if (exportedTypeSymbol) { + error( + name.parent.right, + Diagnostics.Cannot_access_0_1_because_0_is_a_type_but_not_a_namespace_Did_you_mean_to_retrieve_the_type_of_the_property_1_in_0_with_0_1, + symbolToString(exportedTypeSymbol), + unescapeLeadingUnderscores(name.parent.right.escapedText), + ); + return undefined; + } + } + + error(right, Diagnostics.Namespace_0_has_no_exported_member_1, namespaceName, declarationName); + } + return undefined; + } + } + else { + Debug.assertNever(name, "Unknown entity name kind."); + } + if (!nodeIsSynthesized(name) && isEntityName(name) && (symbol.flags & SymbolFlags.Alias || name.parent.kind === SyntaxKind.ExportAssignment)) { + markSymbolOfAliasDeclarationIfTypeOnly(getAliasDeclarationFromName(name), symbol, /*finalTarget*/ undefined, /*overwriteEmpty*/ true); + } + return (symbol.flags & meaning) || dontResolveAlias ? symbol : resolveAlias(symbol); + } + + /** + * 1. For prototype-property methods like `A.prototype.m = function () ...`, try to resolve names in the scope of `A` too. + * Note that prototype-property assignment to locations outside the current file (eg globals) doesn't work, so + * name resolution won't work either. + * 2. For property assignments like `{ x: function f () { } }`, try to resolve names in the scope of `f` too. + */ + function resolveEntityNameFromAssignmentDeclaration(name: Identifier, meaning: SymbolFlags) { + if (isJSDocTypeReference(name.parent)) { + const secondaryLocation = getAssignmentDeclarationLocation(name.parent); + if (secondaryLocation) { + return resolveName(secondaryLocation, name, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + } + } + } + + function getAssignmentDeclarationLocation(node: TypeReferenceNode): Node | undefined { + const typeAlias = findAncestor(node, node => !(isJSDocNode(node) || node.flags & NodeFlags.JSDoc) ? "quit" : isJSDocTypeAlias(node)); + if (typeAlias) { + return; + } + const host = getJSDocHost(node); + if (host && isExpressionStatement(host) && isPrototypePropertyAssignment(host.expression)) { + // /** @param {K} p */ X.prototype.m = function () { } <-- look for K on X's declaration + const symbol = getSymbolOfDeclaration(host.expression.left); + if (symbol) { + return getDeclarationOfJSPrototypeContainer(symbol); + } + } + if (host && isFunctionExpression(host) && isPrototypePropertyAssignment(host.parent) && isExpressionStatement(host.parent.parent)) { + // X.prototype.m = /** @param {K} p */ function () { } <-- look for K on X's declaration + const symbol = getSymbolOfDeclaration(host.parent.left); + if (symbol) { + return getDeclarationOfJSPrototypeContainer(symbol); + } + } + if ( + host && (isObjectLiteralMethod(host) || isPropertyAssignment(host)) && + isBinaryExpression(host.parent.parent) && + getAssignmentDeclarationKind(host.parent.parent) === AssignmentDeclarationKind.Prototype + ) { + // X.prototype = { /** @param {K} p */m() { } } <-- look for K on X's declaration + const symbol = getSymbolOfDeclaration(host.parent.parent.left as BindableStaticNameExpression); + if (symbol) { + return getDeclarationOfJSPrototypeContainer(symbol); + } + } + const sig = getEffectiveJSDocHost(node); + if (sig && isFunctionLike(sig)) { + const symbol = getSymbolOfDeclaration(sig); + return symbol && symbol.valueDeclaration; + } + } + + function getDeclarationOfJSPrototypeContainer(symbol: Symbol) { + const decl = symbol.parent!.valueDeclaration; + if (!decl) { + return undefined; + } + const initializer = isAssignmentDeclaration(decl) ? getAssignedExpandoInitializer(decl) : + hasOnlyExpressionInitializer(decl) ? getDeclaredExpandoInitializer(decl) : + undefined; + return initializer || decl; + } + + /** + * Get the real symbol of a declaration with an expando initializer. + * + * Normally, declarations have an associated symbol, but when a declaration has an expando + * initializer, the expando's symbol is the one that has all the members merged into it. + */ + function getExpandoSymbol(symbol: Symbol): Symbol | undefined { + const decl = symbol.valueDeclaration; + if (!decl || !isInJSFile(decl) || symbol.flags & SymbolFlags.TypeAlias || getExpandoInitializer(decl, /*isPrototypeAssignment*/ false)) { + return undefined; + } + const init = isVariableDeclaration(decl) ? getDeclaredExpandoInitializer(decl) : getAssignedExpandoInitializer(decl); + if (init) { + const initSymbol = getSymbolOfNode(init); + if (initSymbol) { + return mergeJSSymbols(initSymbol, symbol); + } + } + } + + function resolveExternalModuleName(location: Node, moduleReferenceExpression: Expression, ignoreErrors?: boolean): Symbol | undefined { + const isClassic = getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic; + const errorMessage = isClassic ? + Diagnostics.Cannot_find_module_0_Did_you_mean_to_set_the_moduleResolution_option_to_nodenext_or_to_add_aliases_to_the_paths_option + : Diagnostics.Cannot_find_module_0_or_its_corresponding_type_declarations; + return resolveExternalModuleNameWorker(location, moduleReferenceExpression, ignoreErrors ? undefined : errorMessage); + } + + function resolveExternalModuleNameWorker(location: Node, moduleReferenceExpression: Expression, moduleNotFoundError: DiagnosticMessage | undefined, isForAugmentation = false): Symbol | undefined { + return isStringLiteralLike(moduleReferenceExpression) + ? resolveExternalModule(location, moduleReferenceExpression.text, moduleNotFoundError, moduleReferenceExpression, isForAugmentation) + : undefined; + } + + function resolveExternalModule(location: Node, moduleReference: string, moduleNotFoundError: DiagnosticMessage | undefined, errorNode: Node, isForAugmentation = false): Symbol | undefined { + if (startsWith(moduleReference, "@types/")) { + const diag = Diagnostics.Cannot_import_type_declaration_files_Consider_importing_0_instead_of_1; + const withoutAtTypePrefix = removePrefix(moduleReference, "@types/"); + error(errorNode, diag, withoutAtTypePrefix, moduleReference); + } + + const ambientModule = tryFindAmbientModule(moduleReference, /*withAugmentations*/ true); + if (ambientModule) { + return ambientModule; + } + const currentSourceFile = getSourceFileOfNode(location); + const contextSpecifier = isStringLiteralLike(location) + ? location + : (isModuleDeclaration(location) ? location : location.parent && isModuleDeclaration(location.parent) && location.parent.name === location ? location.parent : undefined)?.name || + (isLiteralImportTypeNode(location) ? location : undefined)?.argument.literal || + (isInJSFile(location) && isJSDocImportTag(location) ? location.moduleSpecifier : undefined) || + (isVariableDeclaration(location) && location.initializer && isRequireCall(location.initializer, /*requireStringLiteralLikeArgument*/ true) ? location.initializer.arguments[0] : undefined) || + findAncestor(location, isImportCall)?.arguments[0] || + findAncestor(location, isImportDeclaration)?.moduleSpecifier || + findAncestor(location, isExternalModuleImportEqualsDeclaration)?.moduleReference.expression || + findAncestor(location, isExportDeclaration)?.moduleSpecifier; + const mode = contextSpecifier && isStringLiteralLike(contextSpecifier) ? host.getModeForUsageLocation(currentSourceFile, contextSpecifier) : currentSourceFile.impliedNodeFormat; + const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions); + const resolvedModule = host.getResolvedModule(currentSourceFile, moduleReference, mode)?.resolvedModule; + const resolutionDiagnostic = resolvedModule && getResolutionDiagnostic(compilerOptions, resolvedModule, currentSourceFile); + const sourceFile = resolvedModule + && (!resolutionDiagnostic || resolutionDiagnostic === Diagnostics.Module_0_was_resolved_to_1_but_jsx_is_not_set) + && host.getSourceFile(resolvedModule.resolvedFileName); + if (sourceFile) { + // If there's a resolutionDiagnostic we need to report it even if a sourceFile is found. + if (resolutionDiagnostic) { + error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName); + } + + if (resolvedModule.resolvedUsingTsExtension && isDeclarationFileName(moduleReference)) { + const importOrExport = findAncestor(location, isImportDeclaration)?.importClause || + findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)); + if (importOrExport && !importOrExport.isTypeOnly || findAncestor(location, isImportCall)) { + error( + errorNode, + Diagnostics.A_declaration_file_cannot_be_imported_without_import_type_Did_you_mean_to_import_an_implementation_file_0_instead, + getSuggestedImportSource(Debug.checkDefined(tryExtractTSExtension(moduleReference))), + ); + } + } + else if (resolvedModule.resolvedUsingTsExtension && !shouldAllowImportingTsExtension(compilerOptions, currentSourceFile.fileName)) { + const importOrExport = findAncestor(location, isImportDeclaration)?.importClause || + findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)); + if (!(importOrExport?.isTypeOnly || findAncestor(location, isImportTypeNode))) { + const tsExtension = Debug.checkDefined(tryExtractTSExtension(moduleReference)); + error(errorNode, Diagnostics.An_import_path_can_only_end_with_a_0_extension_when_allowImportingTsExtensions_is_enabled, tsExtension); + } + } + + if (sourceFile.symbol) { + if (resolvedModule.isExternalLibraryImport && !resolutionExtensionIsTSOrJson(resolvedModule.extension)) { + errorOnImplicitAnyModule(/*isError*/ false, errorNode, currentSourceFile, mode, resolvedModule, moduleReference); + } + if (moduleResolutionKind === ModuleResolutionKind.Node16 || moduleResolutionKind === ModuleResolutionKind.NodeNext) { + const isSyncImport = (currentSourceFile.impliedNodeFormat === ModuleKind.CommonJS && !findAncestor(location, isImportCall)) || !!findAncestor(location, isImportEqualsDeclaration); + const overrideHost = findAncestor(location, l => isImportTypeNode(l) || isExportDeclaration(l) || isImportDeclaration(l)) as ImportTypeNode | ImportDeclaration | ExportDeclaration | undefined; + // An override clause will take effect for type-only imports and import types, and allows importing the types across formats, regardless of + // normal mode restrictions + if (isSyncImport && sourceFile.impliedNodeFormat === ModuleKind.ESNext && !hasResolutionModeOverride(overrideHost)) { + if (findAncestor(location, isImportEqualsDeclaration)) { + // ImportEquals in a ESM file resolving to another ESM file + error(errorNode, Diagnostics.Module_0_cannot_be_imported_using_this_construct_The_specifier_only_resolves_to_an_ES_module_which_cannot_be_imported_with_require_Use_an_ECMAScript_import_instead, moduleReference); + } + else { + // CJS file resolving to an ESM file + let diagnosticDetails; + const ext = tryGetExtensionFromPath(currentSourceFile.fileName); + if (ext === Extension.Ts || ext === Extension.Js || ext === Extension.Tsx || ext === Extension.Jsx) { + const scope = currentSourceFile.packageJsonScope; + const targetExt = ext === Extension.Ts ? Extension.Mts : ext === Extension.Js ? Extension.Mjs : undefined; + if (scope && !scope.contents.packageJsonContent.type) { + if (targetExt) { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_add_the_field_type_Colon_module_to_1, + targetExt, + combinePaths(scope.packageDirectory, "package.json"), + ); + } + else { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_add_the_field_type_Colon_module_to_0, + combinePaths(scope.packageDirectory, "package.json"), + ); + } + } + else { + if (targetExt) { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_create_a_local_package_json_file_with_type_Colon_module, + targetExt, + ); + } + else { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_create_a_local_package_json_file_with_type_Colon_module, + ); + } + } + } + diagnostics.add(createDiagnosticForNodeFromMessageChain( + getSourceFileOfNode(errorNode), + errorNode, + chainDiagnosticMessages( + diagnosticDetails, + Diagnostics.The_current_file_is_a_CommonJS_module_whose_imports_will_produce_require_calls_however_the_referenced_file_is_an_ECMAScript_module_and_cannot_be_imported_with_require_Consider_writing_a_dynamic_import_0_call_instead, + moduleReference, + ), + )); + } + } + } + // merged symbol is module declaration symbol combined with all augmentations + return getMergedSymbol(sourceFile.symbol); + } + if (moduleNotFoundError) { + // report errors only if it was requested + error(errorNode, Diagnostics.File_0_is_not_a_module, sourceFile.fileName); + } + return undefined; + } + + if (patternAmbientModules) { + const pattern = findBestPatternMatch(patternAmbientModules, _ => _.pattern, moduleReference); + if (pattern) { + // If the module reference matched a pattern ambient module ('*.foo') but there's also a + // module augmentation by the specific name requested ('a.foo'), we store the merged symbol + // by the augmentation name ('a.foo'), because asking for *.foo should not give you exports + // from a.foo. + const augmentation = patternAmbientModuleAugmentations && patternAmbientModuleAugmentations.get(moduleReference); + if (augmentation) { + return getMergedSymbol(augmentation); + } + return getMergedSymbol(pattern.symbol); + } + } + + // May be an untyped module. If so, ignore resolutionDiagnostic. + if (resolvedModule && !resolutionExtensionIsTSOrJson(resolvedModule.extension) && resolutionDiagnostic === undefined || resolutionDiagnostic === Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type) { + if (isForAugmentation) { + const diag = Diagnostics.Invalid_module_name_in_augmentation_Module_0_resolves_to_an_untyped_module_at_1_which_cannot_be_augmented; + error(errorNode, diag, moduleReference, resolvedModule!.resolvedFileName); + } + else { + errorOnImplicitAnyModule(/*isError*/ noImplicitAny && !!moduleNotFoundError, errorNode, currentSourceFile, mode, resolvedModule!, moduleReference); + } + // Failed imports and untyped modules are both treated in an untyped manner; only difference is whether we give a diagnostic first. + return undefined; + } + + if (moduleNotFoundError) { + // See if this was possibly a projectReference redirect + if (resolvedModule) { + const redirect = host.getProjectReferenceRedirect(resolvedModule.resolvedFileName); + if (redirect) { + error(errorNode, Diagnostics.Output_file_0_has_not_been_built_from_source_file_1, redirect, resolvedModule.resolvedFileName); + return undefined; + } + } + + if (resolutionDiagnostic) { + error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName); + } + else { + const isExtensionlessRelativePathImport = pathIsRelative(moduleReference) && !hasExtension(moduleReference); + const resolutionIsNode16OrNext = moduleResolutionKind === ModuleResolutionKind.Node16 || + moduleResolutionKind === ModuleResolutionKind.NodeNext; + if ( + !getResolveJsonModule(compilerOptions) && + fileExtensionIs(moduleReference, Extension.Json) && + moduleResolutionKind !== ModuleResolutionKind.Classic && + hasJsonModuleEmitEnabled(compilerOptions) + ) { + error(errorNode, Diagnostics.Cannot_find_module_0_Consider_using_resolveJsonModule_to_import_module_with_json_extension, moduleReference); + } + else if (mode === ModuleKind.ESNext && resolutionIsNode16OrNext && isExtensionlessRelativePathImport) { + const absoluteRef = getNormalizedAbsolutePath(moduleReference, getDirectoryPath(currentSourceFile.path)); + const suggestedExt = suggestedExtensions.find(([actualExt, _importExt]) => host.fileExists(absoluteRef + actualExt))?.[1]; + if (suggestedExt) { + error(errorNode, Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_ECMAScript_imports_when_moduleResolution_is_node16_or_nodenext_Did_you_mean_0, moduleReference + suggestedExt); + } + else { + error(errorNode, Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_ECMAScript_imports_when_moduleResolution_is_node16_or_nodenext_Consider_adding_an_extension_to_the_import_path); + } + } + else { + if (host.getResolvedModule(currentSourceFile, moduleReference, mode)?.alternateResult) { + const errorInfo = createModuleNotFoundChain(currentSourceFile, host, moduleReference, mode, moduleReference); + errorOrSuggestion(/*isError*/ true, errorNode, chainDiagnosticMessages(errorInfo, moduleNotFoundError, moduleReference)); + } + else { + error(errorNode, moduleNotFoundError, moduleReference); + } + } + } + } + return undefined; + + function getSuggestedImportSource(tsExtension: string) { + const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension); + /** + * Direct users to import source with .js extension if outputting an ES module. + * @see https://github.com/microsoft/TypeScript/issues/42151 + */ + if (emitModuleKindIsNonNodeESM(moduleKind) || mode === ModuleKind.ESNext) { + const preferTs = isDeclarationFileName(moduleReference) && shouldAllowImportingTsExtension(compilerOptions); + const ext = tsExtension === Extension.Mts || tsExtension === Extension.Dmts ? preferTs ? ".mts" : ".mjs" : + tsExtension === Extension.Cts || tsExtension === Extension.Dmts ? preferTs ? ".cts" : ".cjs" : + preferTs ? ".ts" : ".js"; + return importSourceWithoutExtension + ext; + } + return importSourceWithoutExtension; + } + } + + function errorOnImplicitAnyModule(isError: boolean, errorNode: Node, sourceFile: SourceFile, mode: ResolutionMode, { packageId, resolvedFileName }: ResolvedModuleFull, moduleReference: string): void { + let errorInfo: DiagnosticMessageChain | undefined; + if (!isExternalModuleNameRelative(moduleReference) && packageId) { + errorInfo = createModuleNotFoundChain(sourceFile, host, moduleReference, mode, packageId.name); + } + errorOrSuggestion( + isError, + errorNode, + chainDiagnosticMessages( + errorInfo, + Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type, + moduleReference, + resolvedFileName, + ), + ); + } + + function resolveExternalModuleSymbol(moduleSymbol: Symbol, dontResolveAlias?: boolean): Symbol; + function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined; + function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined { + if (moduleSymbol?.exports) { + const exportEquals = resolveSymbol(moduleSymbol.exports.get(InternalSymbolName.ExportEquals), dontResolveAlias); + const exported = getCommonJsExportEquals(getMergedSymbol(exportEquals), getMergedSymbol(moduleSymbol)); + return getMergedSymbol(exported) || moduleSymbol; + } + return undefined; + } + + function getCommonJsExportEquals(exported: Symbol | undefined, moduleSymbol: Symbol): Symbol | undefined { + if (!exported || exported === unknownSymbol || exported === moduleSymbol || moduleSymbol.exports!.size === 1 || exported.flags & SymbolFlags.Alias) { + return exported; + } + const links = getSymbolLinks(exported); + if (links.cjsExportMerged) { + return links.cjsExportMerged; + } + const merged = exported.flags & SymbolFlags.Transient ? exported : cloneSymbol(exported); + merged.flags = merged.flags | SymbolFlags.ValueModule; + if (merged.exports === undefined) { + merged.exports = createSymbolTable(); + } + moduleSymbol.exports!.forEach((s, name) => { + if (name === InternalSymbolName.ExportEquals) return; + merged.exports!.set(name, merged.exports!.has(name) ? mergeSymbol(merged.exports!.get(name)!, s) : s); + }); + if (merged === exported) { + // We just mutated a symbol, reset any cached links we may have already set + // (Notably required to make late bound members appear) + getSymbolLinks(merged).resolvedExports = undefined; + getSymbolLinks(merged).resolvedMembers = undefined; + } + getSymbolLinks(merged).cjsExportMerged = merged; + return links.cjsExportMerged = merged; + } + + // An external module with an 'export =' declaration may be referenced as an ES6 module provided the 'export =' + // references a symbol that is at least declared as a module or a variable. The target of the 'export =' may + // combine other declarations with the module or variable (e.g. a class/module, function/module, interface/variable). + function resolveESModuleSymbol(moduleSymbol: Symbol | undefined, referencingLocation: Node, dontResolveAlias: boolean, suppressInteropError: boolean): Symbol | undefined { + const symbol = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias); + + if (!dontResolveAlias && symbol) { + if (!suppressInteropError && !(symbol.flags & (SymbolFlags.Module | SymbolFlags.Variable)) && !getDeclarationOfKind(symbol, SyntaxKind.SourceFile)) { + const compilerOptionName = moduleKind >= ModuleKind.ES2015 + ? "allowSyntheticDefaultImports" + : "esModuleInterop"; + + error(referencingLocation, Diagnostics.This_module_can_only_be_referenced_with_ECMAScript_imports_Slashexports_by_turning_on_the_0_flag_and_referencing_its_default_export, compilerOptionName); + + return symbol; + } + + const referenceParent = referencingLocation.parent; + if ( + (isImportDeclaration(referenceParent) && getNamespaceDeclarationNode(referenceParent)) || + isImportCall(referenceParent) + ) { + const reference = isImportCall(referenceParent) ? referenceParent.arguments[0] : referenceParent.moduleSpecifier; + const type = getTypeOfSymbol(symbol); + const defaultOnlyType = getTypeWithSyntheticDefaultOnly(type, symbol, moduleSymbol!, reference); + if (defaultOnlyType) { + return cloneTypeAsModuleType(symbol, defaultOnlyType, referenceParent); + } + + const targetFile = moduleSymbol?.declarations?.find(isSourceFile); + const isEsmCjsRef = targetFile && isESMFormatImportImportingCommonjsFormatFile(getUsageModeForExpression(reference), targetFile.impliedNodeFormat); + if (getESModuleInterop(compilerOptions) || isEsmCjsRef) { + let sigs = getSignaturesOfStructuredType(type, SignatureKind.Call); + if (!sigs || !sigs.length) { + sigs = getSignaturesOfStructuredType(type, SignatureKind.Construct); + } + if ( + (sigs && sigs.length) || + getPropertyOfType(type, InternalSymbolName.Default, /*skipObjectFunctionPropertyAugment*/ true) || + isEsmCjsRef + ) { + const moduleType = type.flags & TypeFlags.StructuredType + ? getTypeWithSyntheticDefaultImportType(type, symbol, moduleSymbol!, reference) + : createDefaultPropertyWrapperForModule(symbol, symbol.parent); + return cloneTypeAsModuleType(symbol, moduleType, referenceParent); + } + } + } + } + return symbol; + } + + /** + * Create a new symbol which has the module's type less the call and construct signatures + */ + function cloneTypeAsModuleType(symbol: Symbol, moduleType: Type, referenceParent: ImportDeclaration | ImportCall) { + const result = createSymbol(symbol.flags, symbol.escapedName); + result.declarations = symbol.declarations ? symbol.declarations.slice() : []; + result.parent = symbol.parent; + result.links.target = symbol; + result.links.originatingImport = referenceParent; + if (symbol.valueDeclaration) result.valueDeclaration = symbol.valueDeclaration; + if (symbol.constEnumOnlyModule) result.constEnumOnlyModule = true; + if (symbol.members) result.members = new Map(symbol.members); + if (symbol.exports) result.exports = new Map(symbol.exports); + const resolvedModuleType = resolveStructuredTypeMembers(moduleType as StructuredType); // Should already be resolved from the signature checks above + result.links.type = createAnonymousType(result, resolvedModuleType.members, emptyArray, emptyArray, resolvedModuleType.indexInfos); + return result; + } + + function hasExportAssignmentSymbol(moduleSymbol: Symbol): boolean { + return moduleSymbol.exports!.get(InternalSymbolName.ExportEquals) !== undefined; + } + + function getExportsOfModuleAsArray(moduleSymbol: Symbol): Symbol[] { + return symbolsToArray(getExportsOfModule(moduleSymbol)); + } + + function getExportsAndPropertiesOfModule(moduleSymbol: Symbol): Symbol[] { + const exports = getExportsOfModuleAsArray(moduleSymbol); + const exportEquals = resolveExternalModuleSymbol(moduleSymbol); + if (exportEquals !== moduleSymbol) { + const type = getTypeOfSymbol(exportEquals); + if (shouldTreatPropertiesOfExternalModuleAsExports(type)) { + addRange(exports, getPropertiesOfType(type)); + } + } + return exports; + } + + function forEachExportAndPropertyOfModule(moduleSymbol: Symbol, cb: (symbol: Symbol, key: __String) => void): void { + const exports = getExportsOfModule(moduleSymbol); + exports.forEach((symbol, key) => { + if (!isReservedMemberName(key)) { + cb(symbol, key); + } + }); + const exportEquals = resolveExternalModuleSymbol(moduleSymbol); + if (exportEquals !== moduleSymbol) { + const type = getTypeOfSymbol(exportEquals); + if (shouldTreatPropertiesOfExternalModuleAsExports(type)) { + forEachPropertyOfType(type, (symbol, escapedName) => { + cb(symbol, escapedName); + }); + } + } + } + + function tryGetMemberInModuleExports(memberName: __String, moduleSymbol: Symbol): Symbol | undefined { + const symbolTable = getExportsOfModule(moduleSymbol); + if (symbolTable) { + return symbolTable.get(memberName); + } + } + + function tryGetMemberInModuleExportsAndProperties(memberName: __String, moduleSymbol: Symbol): Symbol | undefined { + const symbol = tryGetMemberInModuleExports(memberName, moduleSymbol); + if (symbol) { + return symbol; + } + + const exportEquals = resolveExternalModuleSymbol(moduleSymbol); + if (exportEquals === moduleSymbol) { + return undefined; + } + + const type = getTypeOfSymbol(exportEquals); + return shouldTreatPropertiesOfExternalModuleAsExports(type) ? getPropertyOfType(type, memberName) : undefined; + } + + function shouldTreatPropertiesOfExternalModuleAsExports(resolvedExternalModuleType: Type) { + return !(resolvedExternalModuleType.flags & TypeFlags.Primitive || + getObjectFlags(resolvedExternalModuleType) & ObjectFlags.Class || + // `isArrayOrTupleLikeType` is too expensive to use in this auto-imports hot path + isArrayType(resolvedExternalModuleType) || + isTupleType(resolvedExternalModuleType)); + } + + function getExportsOfSymbol(symbol: Symbol): SymbolTable { + return symbol.flags & SymbolFlags.LateBindingContainer ? getResolvedMembersOrExportsOfSymbol(symbol, MembersOrExportsResolutionKind.resolvedExports) : + symbol.flags & SymbolFlags.Module ? getExportsOfModule(symbol) : + symbol.exports || emptySymbols; + } + + function getExportsOfModule(moduleSymbol: Symbol): SymbolTable { + const links = getSymbolLinks(moduleSymbol); + if (!links.resolvedExports) { + const { exports, typeOnlyExportStarMap } = getExportsOfModuleWorker(moduleSymbol); + links.resolvedExports = exports; + links.typeOnlyExportStarMap = typeOnlyExportStarMap; + } + return links.resolvedExports; + } + + interface ExportCollisionTracker { + specifierText: string; + exportsWithDuplicate?: ExportDeclaration[]; + } + + type ExportCollisionTrackerTable = Map<__String, ExportCollisionTracker>; + + /** + * Extends one symbol table with another while collecting information on name collisions for error message generation into the `lookupTable` argument + * Not passing `lookupTable` and `exportNode` disables this collection, and just extends the tables + */ + function extendExportSymbols(target: SymbolTable, source: SymbolTable | undefined, lookupTable?: ExportCollisionTrackerTable, exportNode?: ExportDeclaration) { + if (!source) return; + source.forEach((sourceSymbol, id) => { + if (id === InternalSymbolName.Default) return; + + const targetSymbol = target.get(id); + if (!targetSymbol) { + target.set(id, sourceSymbol); + if (lookupTable && exportNode) { + lookupTable.set(id, { + specifierText: getTextOfNode(exportNode.moduleSpecifier!), + }); + } + } + else if (lookupTable && exportNode && targetSymbol && resolveSymbol(targetSymbol) !== resolveSymbol(sourceSymbol)) { + const collisionTracker = lookupTable.get(id)!; + if (!collisionTracker.exportsWithDuplicate) { + collisionTracker.exportsWithDuplicate = [exportNode]; + } + else { + collisionTracker.exportsWithDuplicate.push(exportNode); + } + } + }); + } + + function getExportsOfModuleWorker(moduleSymbol: Symbol) { + const visitedSymbols: Symbol[] = []; + let typeOnlyExportStarMap: Map<__String, ExportDeclaration & { readonly isTypeOnly: true; readonly moduleSpecifier: Expression; }> | undefined; + const nonTypeOnlyNames = new Set<__String>(); + + // A module defined by an 'export=' consists of one export that needs to be resolved + moduleSymbol = resolveExternalModuleSymbol(moduleSymbol); + const exports = visit(moduleSymbol) || emptySymbols; + + if (typeOnlyExportStarMap) { + nonTypeOnlyNames.forEach(name => typeOnlyExportStarMap!.delete(name)); + } + + return { + exports, + typeOnlyExportStarMap, + }; + + // The ES6 spec permits export * declarations in a module to circularly reference the module itself. For example, + // module 'a' can 'export * from "b"' and 'b' can 'export * from "a"' without error. + function visit(symbol: Symbol | undefined, exportStar?: ExportDeclaration, isTypeOnly?: boolean): SymbolTable | undefined { + if (!isTypeOnly && symbol?.exports) { + // Add non-type-only names before checking if we've visited this module, + // because we might have visited it via an 'export type *', and visiting + // again with 'export *' will override the type-onlyness of its exports. + symbol.exports.forEach((_, name) => nonTypeOnlyNames.add(name)); + } + if (!(symbol && symbol.exports && pushIfUnique(visitedSymbols, symbol))) { + return; + } + const symbols = new Map(symbol.exports); + + // All export * declarations are collected in an __export symbol by the binder + const exportStars = symbol.exports.get(InternalSymbolName.ExportStar); + if (exportStars) { + const nestedSymbols = createSymbolTable(); + const lookupTable: ExportCollisionTrackerTable = new Map(); + if (exportStars.declarations) { + for (const node of exportStars.declarations) { + const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!); + const exportedSymbols = visit(resolvedModule, node as ExportDeclaration, isTypeOnly || (node as ExportDeclaration).isTypeOnly); + extendExportSymbols( + nestedSymbols, + exportedSymbols, + lookupTable, + node as ExportDeclaration, + ); + } + } + lookupTable.forEach(({ exportsWithDuplicate }, id) => { + // It's not an error if the file with multiple `export *`s with duplicate names exports a member with that name itself + if (id === "export=" || !(exportsWithDuplicate && exportsWithDuplicate.length) || symbols.has(id)) { + return; + } + for (const node of exportsWithDuplicate) { + diagnostics.add(createDiagnosticForNode( + node, + Diagnostics.Module_0_has_already_exported_a_member_named_1_Consider_explicitly_re_exporting_to_resolve_the_ambiguity, + lookupTable.get(id)!.specifierText, + unescapeLeadingUnderscores(id), + )); + } + }); + extendExportSymbols(symbols, nestedSymbols); + } + if (exportStar?.isTypeOnly) { + typeOnlyExportStarMap ??= new Map(); + symbols.forEach((_, escapedName) => + typeOnlyExportStarMap!.set( + escapedName, + exportStar as ExportDeclaration & { readonly isTypeOnly: true; readonly moduleSpecifier: Expression; }, + ) + ); + } + return symbols; + } + } + + function getMergedSymbol(symbol: Symbol): Symbol; + function getMergedSymbol(symbol: Symbol | undefined): Symbol | undefined; + function getMergedSymbol(symbol: Symbol | undefined): Symbol | undefined { + let merged: Symbol; + return symbol && symbol.mergeId && (merged = mergedSymbols[symbol.mergeId]) ? merged : symbol; + } + + function getSymbolOfDeclaration(node: Declaration): Symbol { + return getMergedSymbol(node.symbol && getLateBoundSymbol(node.symbol)); + } + + /** + * Get the merged symbol for a node. If you know the node is a `Declaration`, it is faster and more type safe to + * use use `getSymbolOfDeclaration` instead. + */ + function getSymbolOfNode(node: Node): Symbol | undefined { + return canHaveSymbol(node) ? getSymbolOfDeclaration(node) : undefined; + } + + function getParentOfSymbol(symbol: Symbol): Symbol | undefined { + return getMergedSymbol(symbol.parent && getLateBoundSymbol(symbol.parent)); + } + + function getFunctionExpressionParentSymbolOrSymbol(symbol: Symbol) { + return symbol.valueDeclaration?.kind === SyntaxKind.ArrowFunction || symbol.valueDeclaration?.kind === SyntaxKind.FunctionExpression + ? getSymbolOfNode(symbol.valueDeclaration.parent) || symbol + : symbol; + } + + function getAlternativeContainingModules(symbol: Symbol, enclosingDeclaration: Node): Symbol[] { + const containingFile = getSourceFileOfNode(enclosingDeclaration); + const id = getNodeId(containingFile); + const links = getSymbolLinks(symbol); + let results: Symbol[] | undefined; + if (links.extendedContainersByFile && (results = links.extendedContainersByFile.get(id))) { + return results; + } + if (containingFile && containingFile.imports) { + // Try to make an import using an import already in the enclosing file, if possible + for (const importRef of containingFile.imports) { + if (nodeIsSynthesized(importRef)) continue; // Synthetic names can't be resolved by `resolveExternalModuleName` - they'll cause a debug assert if they error + const resolvedModule = resolveExternalModuleName(enclosingDeclaration, importRef, /*ignoreErrors*/ true); + if (!resolvedModule) continue; + const ref = getAliasForSymbolInContainer(resolvedModule, symbol); + if (!ref) continue; + results = append(results, resolvedModule); + } + if (length(results)) { + (links.extendedContainersByFile || (links.extendedContainersByFile = new Map())).set(id, results!); + return results!; + } + } + if (links.extendedContainers) { + return links.extendedContainers; + } + // No results from files already being imported by this file - expand search (expensive, but not location-specific, so cached) + const otherFiles = host.getSourceFiles(); + for (const file of otherFiles) { + if (!isExternalModule(file)) continue; + const sym = getSymbolOfDeclaration(file); + const ref = getAliasForSymbolInContainer(sym, symbol); + if (!ref) continue; + results = append(results, sym); + } + return links.extendedContainers = results || emptyArray; + } + + /** + * Attempts to find the symbol corresponding to the container a symbol is in - usually this + * is just its' `.parent`, but for locals, this value is `undefined` + */ + function getContainersOfSymbol(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags): Symbol[] | undefined { + const container = getParentOfSymbol(symbol); + // Type parameters end up in the `members` lists but are not externally visible + if (container && !(symbol.flags & SymbolFlags.TypeParameter)) { + return getWithAlternativeContainers(container); + } + const candidates = mapDefined(symbol.declarations, d => { + if (!isAmbientModule(d) && d.parent) { + // direct children of a module + if (hasNonGlobalAugmentationExternalModuleSymbol(d.parent)) { + return getSymbolOfDeclaration(d.parent as Declaration); + } + // export ='d member of an ambient module + if (isModuleBlock(d.parent) && d.parent.parent && resolveExternalModuleSymbol(getSymbolOfDeclaration(d.parent.parent)) === symbol) { + return getSymbolOfDeclaration(d.parent.parent); + } + } + if (isClassExpression(d) && isBinaryExpression(d.parent) && d.parent.operatorToken.kind === SyntaxKind.EqualsToken && isAccessExpression(d.parent.left) && isEntityNameExpression(d.parent.left.expression)) { + if (isModuleExportsAccessExpression(d.parent.left) || isExportsIdentifier(d.parent.left.expression)) { + return getSymbolOfDeclaration(getSourceFileOfNode(d)); + } + checkExpressionCached(d.parent.left.expression); + return getNodeLinks(d.parent.left.expression).resolvedSymbol; + } + }); + if (!length(candidates)) { + return undefined; + } + const containers = mapDefined(candidates, candidate => getAliasForSymbolInContainer(candidate, symbol) ? candidate : undefined); + + let bestContainers: Symbol[] = []; + let alternativeContainers: Symbol[] = []; + + for (const container of containers) { + const [bestMatch, ...rest] = getWithAlternativeContainers(container); + bestContainers = append(bestContainers, bestMatch); + alternativeContainers = addRange(alternativeContainers, rest); + } + + return concatenate(bestContainers, alternativeContainers); + + function getWithAlternativeContainers(container: Symbol) { + const additionalContainers = mapDefined(container.declarations, fileSymbolIfFileSymbolExportEqualsContainer); + const reexportContainers = enclosingDeclaration && getAlternativeContainingModules(symbol, enclosingDeclaration); + const objectLiteralContainer = getVariableDeclarationOfObjectLiteral(container, meaning); + if ( + enclosingDeclaration && + container.flags & getQualifiedLeftMeaning(meaning) && + getAccessibleSymbolChain(container, enclosingDeclaration, SymbolFlags.Namespace, /*useOnlyExternalAliasing*/ false) + ) { + return append(concatenate(concatenate([container], additionalContainers), reexportContainers), objectLiteralContainer); // This order expresses a preference for the real container if it is in scope + } + // we potentially have a symbol which is a member of the instance side of something - look for a variable in scope with the container's type + // which may be acting like a namespace (eg, `Symbol` acts like a namespace when looking up `Symbol.toStringTag`) + const firstVariableMatch = !(container.flags & getQualifiedLeftMeaning(meaning)) + && container.flags & SymbolFlags.Type + && getDeclaredTypeOfSymbol(container).flags & TypeFlags.Object + && meaning === SymbolFlags.Value + ? forEachSymbolTableInScope(enclosingDeclaration, t => { + return forEachEntry(t, s => { + if (s.flags & getQualifiedLeftMeaning(meaning) && getTypeOfSymbol(s) === getDeclaredTypeOfSymbol(container)) { + return s; + } + }); + }) : undefined; + let res = firstVariableMatch ? [firstVariableMatch, ...additionalContainers, container] : [...additionalContainers, container]; + res = append(res, objectLiteralContainer); + res = addRange(res, reexportContainers); + return res; + } + + function fileSymbolIfFileSymbolExportEqualsContainer(d: Declaration) { + return container && getFileSymbolIfFileSymbolExportEqualsContainer(d, container); + } + } + + function getVariableDeclarationOfObjectLiteral(symbol: Symbol, meaning: SymbolFlags) { + // If we're trying to reference some object literal in, eg `var a = { x: 1 }`, the symbol for the literal, `__object`, is distinct + // from the symbol of the declaration it is being assigned to. Since we can use the declaration to refer to the literal, however, + // we'd like to make that connection here - potentially causing us to paint the declaration's visibility, and therefore the literal. + const firstDecl: Node | false = !!length(symbol.declarations) && first(symbol.declarations!); + if (meaning & SymbolFlags.Value && firstDecl && firstDecl.parent && isVariableDeclaration(firstDecl.parent)) { + if (isObjectLiteralExpression(firstDecl) && firstDecl === firstDecl.parent.initializer || isTypeLiteralNode(firstDecl) && firstDecl === firstDecl.parent.type) { + return getSymbolOfDeclaration(firstDecl.parent); + } + } + } + + function getFileSymbolIfFileSymbolExportEqualsContainer(d: Declaration, container: Symbol) { + const fileSymbol = getExternalModuleContainer(d); + const exported = fileSymbol && fileSymbol.exports && fileSymbol.exports.get(InternalSymbolName.ExportEquals); + return exported && getSymbolIfSameReference(exported, container) ? fileSymbol : undefined; + } + + function getAliasForSymbolInContainer(container: Symbol, symbol: Symbol) { + if (container === getParentOfSymbol(symbol)) { + // fast path, `symbol` is either already the alias or isn't aliased + return symbol; + } + // Check if container is a thing with an `export=` which points directly at `symbol`, and if so, return + // the container itself as the alias for the symbol + const exportEquals = container.exports && container.exports.get(InternalSymbolName.ExportEquals); + if (exportEquals && getSymbolIfSameReference(exportEquals, symbol)) { + return container; + } + const exports = getExportsOfSymbol(container); + const quick = exports.get(symbol.escapedName); + if (quick && getSymbolIfSameReference(quick, symbol)) { + return quick; + } + return forEachEntry(exports, exported => { + if (getSymbolIfSameReference(exported, symbol)) { + return exported; + } + }); + } + + /** + * Checks if two symbols, through aliasing and/or merging, refer to the same thing + */ + function getSymbolIfSameReference(s1: Symbol, s2: Symbol) { + if (getMergedSymbol(resolveSymbol(getMergedSymbol(s1))) === getMergedSymbol(resolveSymbol(getMergedSymbol(s2)))) { + return s1; + } + } + + function getExportSymbolOfValueSymbolIfExported(symbol: Symbol): Symbol; + function getExportSymbolOfValueSymbolIfExported(symbol: Symbol | undefined): Symbol | undefined; + function getExportSymbolOfValueSymbolIfExported(symbol: Symbol | undefined): Symbol | undefined { + return getMergedSymbol(symbol && (symbol.flags & SymbolFlags.ExportValue) !== 0 && symbol.exportSymbol || symbol); + } + + function symbolIsValue(symbol: Symbol, includeTypeOnlyMembers?: boolean): boolean { + return !!( + symbol.flags & SymbolFlags.Value || + symbol.flags & SymbolFlags.Alias && getSymbolFlags(symbol, !includeTypeOnlyMembers) & SymbolFlags.Value + ); + } + + function createType(flags: TypeFlags): Type { + const result = new Type(checker, flags); + typeCount++; + result.id = typeCount; + tracing?.recordType(result); + return result; + } + + function createTypeWithSymbol(flags: TypeFlags, symbol: Symbol): Type { + const result = createType(flags); + result.symbol = symbol; + return result; + } + + function createOriginType(flags: TypeFlags): Type { + return new Type(checker, flags); + } + + function createIntrinsicType(kind: TypeFlags, intrinsicName: string, objectFlags = ObjectFlags.None, debugIntrinsicName?: string): IntrinsicType { + checkIntrinsicName(intrinsicName, debugIntrinsicName); + const type = createType(kind) as IntrinsicType; + type.intrinsicName = intrinsicName; + type.debugIntrinsicName = debugIntrinsicName; + type.objectFlags = objectFlags | ObjectFlags.CouldContainTypeVariablesComputed | ObjectFlags.IsGenericTypeComputed | ObjectFlags.IsUnknownLikeUnionComputed | ObjectFlags.IsNeverIntersectionComputed; + return type; + } + + function checkIntrinsicName(name: string, debug: string | undefined) { + const key = `${name},${debug ?? ""}`; + if (seenIntrinsicNames.has(key)) { + Debug.fail(`Duplicate intrinsic type name ${name}${debug ? ` (${debug})` : ""}; you may need to pass a name to createIntrinsicType.`); + } + seenIntrinsicNames.add(key); + } + + function createObjectType(objectFlags: ObjectFlags, symbol?: Symbol): ObjectType { + const type = createTypeWithSymbol(TypeFlags.Object, symbol!) as ObjectType; + type.objectFlags = objectFlags; + type.members = undefined; + type.properties = undefined; + type.callSignatures = undefined; + type.constructSignatures = undefined; + type.indexInfos = undefined; + return type; + } + + function createTypeofType() { + return getUnionType(arrayFrom(typeofNEFacts.keys(), getStringLiteralType)); + } + + function createTypeParameter(symbol?: Symbol) { + return createTypeWithSymbol(TypeFlags.TypeParameter, symbol!) as TypeParameter; + } + + // A reserved member name starts with two underscores, but the third character cannot be an underscore, + // @, or #. A third underscore indicates an escaped form of an identifier that started + // with at least two underscores. The @ character indicates that the name is denoted by a well known ES + // Symbol instance and the # character indicates that the name is a PrivateIdentifier. + function isReservedMemberName(name: __String) { + return (name as string).charCodeAt(0) === CharacterCodes._ && + (name as string).charCodeAt(1) === CharacterCodes._ && + (name as string).charCodeAt(2) !== CharacterCodes._ && + (name as string).charCodeAt(2) !== CharacterCodes.at && + (name as string).charCodeAt(2) !== CharacterCodes.hash; + } + + function getNamedMembers(members: SymbolTable): Symbol[] { + let result: Symbol[] | undefined; + members.forEach((symbol, id) => { + if (isNamedMember(symbol, id)) { + (result || (result = [])).push(symbol); + } + }); + return result || emptyArray; + } + + function isNamedMember(member: Symbol, escapedName: __String) { + return !isReservedMemberName(escapedName) && symbolIsValue(member); + } + + function getNamedOrIndexSignatureMembers(members: SymbolTable): Symbol[] { + const result = getNamedMembers(members); + const index = getIndexSymbolFromSymbolTable(members); + return index ? concatenate(result, [index]) : result; + } + + function setStructuredTypeMembers(type: StructuredType, members: SymbolTable, callSignatures: readonly Signature[], constructSignatures: readonly Signature[], indexInfos: readonly IndexInfo[]): ResolvedType { + const resolved = type as ResolvedType; + resolved.members = members; + resolved.properties = emptyArray; + resolved.callSignatures = callSignatures; + resolved.constructSignatures = constructSignatures; + resolved.indexInfos = indexInfos; + // This can loop back to getPropertyOfType() which would crash if `callSignatures` & `constructSignatures` are not initialized. + if (members !== emptySymbols) resolved.properties = getNamedMembers(members); + return resolved; + } + + function createAnonymousType(symbol: Symbol | undefined, members: SymbolTable, callSignatures: readonly Signature[], constructSignatures: readonly Signature[], indexInfos: readonly IndexInfo[]): ResolvedType { + return setStructuredTypeMembers(createObjectType(ObjectFlags.Anonymous, symbol), members, callSignatures, constructSignatures, indexInfos); + } + + function getResolvedTypeWithoutAbstractConstructSignatures(type: ResolvedType) { + if (type.constructSignatures.length === 0) return type; + if (type.objectTypeWithoutAbstractConstructSignatures) return type.objectTypeWithoutAbstractConstructSignatures; + const constructSignatures = filter(type.constructSignatures, signature => !(signature.flags & SignatureFlags.Abstract)); + if (type.constructSignatures === constructSignatures) return type; + const typeCopy = createAnonymousType( + type.symbol, + type.members, + type.callSignatures, + some(constructSignatures) ? constructSignatures : emptyArray, + type.indexInfos, + ); + type.objectTypeWithoutAbstractConstructSignatures = typeCopy; + typeCopy.objectTypeWithoutAbstractConstructSignatures = typeCopy; + return typeCopy; + } + + function forEachSymbolTableInScope(enclosingDeclaration: Node | undefined, callback: (symbolTable: SymbolTable, ignoreQualification?: boolean, isLocalNameLookup?: boolean, scopeNode?: Node) => T): T { + let result: T; + for (let location = enclosingDeclaration; location; location = location.parent) { + // Locals of a source file are not in scope (because they get merged into the global symbol table) + if (canHaveLocals(location) && location.locals && !isGlobalSourceFile(location)) { + if (result = callback(location.locals, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true, location)) { + return result; + } + } + switch (location.kind) { + case SyntaxKind.SourceFile: + if (!isExternalOrCommonJsModule(location as SourceFile)) { + break; + } + // falls through + case SyntaxKind.ModuleDeclaration: + const sym = getSymbolOfDeclaration(location as ModuleDeclaration); + // `sym` may not have exports if this module declaration is backed by the symbol for a `const` that's being rewritten + // into a namespace - in such cases, it's best to just let the namespace appear empty (the const members couldn't have referred + // to one another anyway) + if (result = callback(sym?.exports || emptySymbols, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true, location)) { + return result; + } + break; + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + case SyntaxKind.InterfaceDeclaration: + // Type parameters are bound into `members` lists so they can merge across declarations + // This is troublesome, since in all other respects, they behave like locals :cries: + // TODO: the below is shared with similar code in `resolveName` - in fact, rephrasing all this symbol + // lookup logic in terms of `resolveName` would be nice + // The below is used to lookup type parameters within a class or interface, as they are added to the class/interface locals + // These can never be latebound, so the symbol's raw members are sufficient. `getMembersOfNode` cannot be used, as it would + // trigger resolving late-bound names, which we may already be in the process of doing while we're here! + let table: Map<__String, Symbol> | undefined; + // TODO: Should this filtered table be cached in some way? + (getSymbolOfDeclaration(location as ClassLikeDeclaration | InterfaceDeclaration).members || emptySymbols).forEach((memberSymbol, key) => { + if (memberSymbol.flags & (SymbolFlags.Type & ~SymbolFlags.Assignment)) { + (table || (table = createSymbolTable())).set(key, memberSymbol); + } + }); + if (table && (result = callback(table, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ false, location))) { + return result; + } + break; + } + } + + return callback(globals, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true); + } + + function getQualifiedLeftMeaning(rightMeaning: SymbolFlags) { + // If we are looking in value space, the parent meaning is value, other wise it is namespace + return rightMeaning === SymbolFlags.Value ? SymbolFlags.Value : SymbolFlags.Namespace; + } + + function getAccessibleSymbolChain(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, useOnlyExternalAliasing: boolean, visitedSymbolTablesMap = new Map()): Symbol[] | undefined { + if (!(symbol && !isPropertyOrMethodDeclarationSymbol(symbol))) { + return undefined; + } + const links = getSymbolLinks(symbol); + const cache = (links.accessibleChainCache ||= new Map()); + // Go from enclosingDeclaration to the first scope we check, so the cache is keyed off the scope and thus shared more + const firstRelevantLocation = forEachSymbolTableInScope(enclosingDeclaration, (_, __, ___, node) => node); + const key = `${useOnlyExternalAliasing ? 0 : 1}|${firstRelevantLocation && getNodeId(firstRelevantLocation)}|${meaning}`; + if (cache.has(key)) { + return cache.get(key); + } + + const id = getSymbolId(symbol); + let visitedSymbolTables = visitedSymbolTablesMap.get(id); + if (!visitedSymbolTables) { + visitedSymbolTablesMap.set(id, visitedSymbolTables = []); + } + const result = forEachSymbolTableInScope(enclosingDeclaration, getAccessibleSymbolChainFromSymbolTable); + cache.set(key, result); + return result; + + /** + * @param {ignoreQualification} boolean Set when a symbol is being looked for through the exports of another symbol (meaning we have a route to qualify it already) + */ + function getAccessibleSymbolChainFromSymbolTable(symbols: SymbolTable, ignoreQualification?: boolean, isLocalNameLookup?: boolean): Symbol[] | undefined { + if (!pushIfUnique(visitedSymbolTables!, symbols)) { + return undefined; + } + + const result = trySymbolTable(symbols, ignoreQualification, isLocalNameLookup); + visitedSymbolTables!.pop(); + return result; + } + + function canQualifySymbol(symbolFromSymbolTable: Symbol, meaning: SymbolFlags) { + // If the symbol is equivalent and doesn't need further qualification, this symbol is accessible + return !needsQualification(symbolFromSymbolTable, enclosingDeclaration, meaning) || + // If symbol needs qualification, make sure that parent is accessible, if it is then this symbol is accessible too + !!getAccessibleSymbolChain(symbolFromSymbolTable.parent, enclosingDeclaration, getQualifiedLeftMeaning(meaning), useOnlyExternalAliasing, visitedSymbolTablesMap); + } + + function isAccessible(symbolFromSymbolTable: Symbol, resolvedAliasSymbol?: Symbol, ignoreQualification?: boolean) { + return (symbol === (resolvedAliasSymbol || symbolFromSymbolTable) || getMergedSymbol(symbol) === getMergedSymbol(resolvedAliasSymbol || symbolFromSymbolTable)) && + // if the symbolFromSymbolTable is not external module (it could be if it was determined as ambient external module and would be in globals table) + // and if symbolFromSymbolTable or alias resolution matches the symbol, + // check the symbol can be qualified, it is only then this symbol is accessible + !some(symbolFromSymbolTable.declarations, hasNonGlobalAugmentationExternalModuleSymbol) && + (ignoreQualification || canQualifySymbol(getMergedSymbol(symbolFromSymbolTable), meaning)); + } + + function trySymbolTable(symbols: SymbolTable, ignoreQualification: boolean | undefined, isLocalNameLookup: boolean | undefined): Symbol[] | undefined { + // If symbol is directly available by its name in the symbol table + if (isAccessible(symbols.get(symbol!.escapedName)!, /*resolvedAliasSymbol*/ undefined, ignoreQualification)) { + return [symbol!]; + } + + // Check if symbol is any of the aliases in scope + const result = forEachEntry(symbols, symbolFromSymbolTable => { + if ( + symbolFromSymbolTable.flags & SymbolFlags.Alias + && symbolFromSymbolTable.escapedName !== InternalSymbolName.ExportEquals + && symbolFromSymbolTable.escapedName !== InternalSymbolName.Default + && !(isUMDExportSymbol(symbolFromSymbolTable) && enclosingDeclaration && isExternalModule(getSourceFileOfNode(enclosingDeclaration))) + // If `!useOnlyExternalAliasing`, we can use any type of alias to get the name + && (!useOnlyExternalAliasing || some(symbolFromSymbolTable.declarations, isExternalModuleImportEqualsDeclaration)) + // If we're looking up a local name to reference directly, omit namespace reexports, otherwise when we're trawling through an export list to make a dotted name, we can keep it + && (isLocalNameLookup ? !some(symbolFromSymbolTable.declarations, isNamespaceReexportDeclaration) : true) + // While exports are generally considered to be in scope, export-specifier declared symbols are _not_ + // See similar comment in `resolveName` for details + && (ignoreQualification || !getDeclarationOfKind(symbolFromSymbolTable, SyntaxKind.ExportSpecifier)) + ) { + const resolvedImportedSymbol = resolveAlias(symbolFromSymbolTable); + const candidate = getCandidateListForSymbol(symbolFromSymbolTable, resolvedImportedSymbol, ignoreQualification); + if (candidate) { + return candidate; + } + } + if (symbolFromSymbolTable.escapedName === symbol!.escapedName && symbolFromSymbolTable.exportSymbol) { + if (isAccessible(getMergedSymbol(symbolFromSymbolTable.exportSymbol), /*resolvedAliasSymbol*/ undefined, ignoreQualification)) { + return [symbol!]; + } + } + }); + + // If there's no result and we're looking at the global symbol table, treat `globalThis` like an alias and try to lookup thru that + return result || (symbols === globals ? getCandidateListForSymbol(globalThisSymbol, globalThisSymbol, ignoreQualification) : undefined); + } + + function getCandidateListForSymbol(symbolFromSymbolTable: Symbol, resolvedImportedSymbol: Symbol, ignoreQualification: boolean | undefined) { + if (isAccessible(symbolFromSymbolTable, resolvedImportedSymbol, ignoreQualification)) { + return [symbolFromSymbolTable]; + } + + // Look in the exported members, if we can find accessibleSymbolChain, symbol is accessible using this chain + // but only if the symbolFromSymbolTable can be qualified + const candidateTable = getExportsOfSymbol(resolvedImportedSymbol); + const accessibleSymbolsFromExports = candidateTable && getAccessibleSymbolChainFromSymbolTable(candidateTable, /*ignoreQualification*/ true); + if (accessibleSymbolsFromExports && canQualifySymbol(symbolFromSymbolTable, getQualifiedLeftMeaning(meaning))) { + return [symbolFromSymbolTable].concat(accessibleSymbolsFromExports); + } + } + } + + function needsQualification(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags) { + let qualify = false; + forEachSymbolTableInScope(enclosingDeclaration, symbolTable => { + // If symbol of this name is not available in the symbol table we are ok + let symbolFromSymbolTable = getMergedSymbol(symbolTable.get(symbol.escapedName)); + if (!symbolFromSymbolTable) { + // Continue to the next symbol table + return false; + } + // If the symbol with this name is present it should refer to the symbol + if (symbolFromSymbolTable === symbol) { + // No need to qualify + return true; + } + + // Qualify if the symbol from symbol table has same meaning as expected + const shouldResolveAlias = symbolFromSymbolTable.flags & SymbolFlags.Alias && !getDeclarationOfKind(symbolFromSymbolTable, SyntaxKind.ExportSpecifier); + symbolFromSymbolTable = shouldResolveAlias ? resolveAlias(symbolFromSymbolTable) : symbolFromSymbolTable; + const flags = shouldResolveAlias ? getSymbolFlags(symbolFromSymbolTable) : symbolFromSymbolTable.flags; + if (flags & meaning) { + qualify = true; + return true; + } + + // Continue to the next symbol table + return false; + }); + + return qualify; + } + + function isPropertyOrMethodDeclarationSymbol(symbol: Symbol) { + if (symbol.declarations && symbol.declarations.length) { + for (const declaration of symbol.declarations) { + switch (declaration.kind) { + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + continue; + default: + return false; + } + } + return true; + } + return false; + } + + function isTypeSymbolAccessible(typeSymbol: Symbol, enclosingDeclaration: Node | undefined): boolean { + const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, SymbolFlags.Type, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ true); + return access.accessibility === SymbolAccessibility.Accessible; + } + + function isValueSymbolAccessible(typeSymbol: Symbol, enclosingDeclaration: Node | undefined): boolean { + const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, SymbolFlags.Value, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ true); + return access.accessibility === SymbolAccessibility.Accessible; + } + + function isSymbolAccessibleByFlags(typeSymbol: Symbol, enclosingDeclaration: Node | undefined, flags: SymbolFlags): boolean { + const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, flags, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ false); + return access.accessibility === SymbolAccessibility.Accessible; + } + + function isAnySymbolAccessible(symbols: Symbol[] | undefined, enclosingDeclaration: Node | undefined, initialSymbol: Symbol, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean, allowModules: boolean): SymbolAccessibilityResult | undefined { + if (!length(symbols)) return; + + let hadAccessibleChain: Symbol | undefined; + let earlyModuleBail = false; + for (const symbol of symbols!) { + // Symbol is accessible if it by itself is accessible + const accessibleSymbolChain = getAccessibleSymbolChain(symbol, enclosingDeclaration, meaning, /*useOnlyExternalAliasing*/ false); + if (accessibleSymbolChain) { + hadAccessibleChain = symbol; + const hasAccessibleDeclarations = hasVisibleDeclarations(accessibleSymbolChain[0], shouldComputeAliasesToMakeVisible); + if (hasAccessibleDeclarations) { + return hasAccessibleDeclarations; + } + } + if (allowModules) { + if (some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + if (shouldComputeAliasesToMakeVisible) { + earlyModuleBail = true; + // Generally speaking, we want to use the aliases that already exist to refer to a module, if present + // In order to do so, we need to find those aliases in order to retain them in declaration emit; so + // if we are in declaration emit, we cannot use the fast path for module visibility until we've exhausted + // all other visibility options (in order to capture the possible aliases used to reference the module) + continue; + } + // Any meaning of a module symbol is always accessible via an `import` type + return { + accessibility: SymbolAccessibility.Accessible, + }; + } + } + + // If we haven't got the accessible symbol, it doesn't mean the symbol is actually inaccessible. + // It could be a qualified symbol and hence verify the path + // e.g.: + // module m { + // export class c { + // } + // } + // const x: typeof m.c + // In the above example when we start with checking if typeof m.c symbol is accessible, + // we are going to see if c can be accessed in scope directly. + // But it can't, hence the accessible is going to be undefined, but that doesn't mean m.c is inaccessible + // It is accessible if the parent m is accessible because then m.c can be accessed through qualification + + const containers = getContainersOfSymbol(symbol, enclosingDeclaration, meaning); + const parentResult = isAnySymbolAccessible(containers, enclosingDeclaration, initialSymbol, initialSymbol === symbol ? getQualifiedLeftMeaning(meaning) : meaning, shouldComputeAliasesToMakeVisible, allowModules); + if (parentResult) { + return parentResult; + } + } + + if (earlyModuleBail) { + return { + accessibility: SymbolAccessibility.Accessible, + }; + } + + if (hadAccessibleChain) { + return { + accessibility: SymbolAccessibility.NotAccessible, + errorSymbolName: symbolToString(initialSymbol, enclosingDeclaration, meaning), + errorModuleName: hadAccessibleChain !== initialSymbol ? symbolToString(hadAccessibleChain, enclosingDeclaration, SymbolFlags.Namespace) : undefined, + }; + } + } + + /** + * Check if the given symbol in given enclosing declaration is accessible and mark all associated alias to be visible if requested + * + * @param symbol a Symbol to check if accessible + * @param enclosingDeclaration a Node containing reference to the symbol + * @param meaning a SymbolFlags to check if such meaning of the symbol is accessible + * @param shouldComputeAliasToMakeVisible a boolean value to indicate whether to return aliases to be mark visible in case the symbol is accessible + */ + function isSymbolAccessible(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean): SymbolAccessibilityResult { + return isSymbolAccessibleWorker(symbol, enclosingDeclaration, meaning, shouldComputeAliasesToMakeVisible, /*allowModules*/ true); + } + + function isSymbolAccessibleWorker(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean, allowModules: boolean): SymbolAccessibilityResult { + if (symbol && enclosingDeclaration) { + const result = isAnySymbolAccessible([symbol], enclosingDeclaration, symbol, meaning, shouldComputeAliasesToMakeVisible, allowModules); + if (result) { + return result; + } + + // This could be a symbol that is not exported in the external module + // or it could be a symbol from different external module that is not aliased and hence cannot be named + const symbolExternalModule = forEach(symbol.declarations, getExternalModuleContainer); + if (symbolExternalModule) { + const enclosingExternalModule = getExternalModuleContainer(enclosingDeclaration); + if (symbolExternalModule !== enclosingExternalModule) { + // name from different external module that is not visible + return { + accessibility: SymbolAccessibility.CannotBeNamed, + errorSymbolName: symbolToString(symbol, enclosingDeclaration, meaning), + errorModuleName: symbolToString(symbolExternalModule), + errorNode: isInJSFile(enclosingDeclaration) ? enclosingDeclaration : undefined, + }; + } + } + + // Just a local name that is not accessible + return { + accessibility: SymbolAccessibility.NotAccessible, + errorSymbolName: symbolToString(symbol, enclosingDeclaration, meaning), + }; + } + + return { accessibility: SymbolAccessibility.Accessible }; + } + + function getExternalModuleContainer(declaration: Node) { + const node = findAncestor(declaration, hasExternalModuleSymbol); + return node && getSymbolOfDeclaration(node as AmbientModuleDeclaration | SourceFile); + } + + function hasExternalModuleSymbol(declaration: Node) { + return isAmbientModule(declaration) || (declaration.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(declaration as SourceFile)); + } + + function hasNonGlobalAugmentationExternalModuleSymbol(declaration: Node) { + return isModuleWithStringLiteralName(declaration) || (declaration.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(declaration as SourceFile)); + } + + function hasVisibleDeclarations(symbol: Symbol, shouldComputeAliasToMakeVisible: boolean): SymbolVisibilityResult | undefined { + let aliasesToMakeVisible: LateVisibilityPaintedStatement[] | undefined; + if (!every(filter(symbol.declarations, d => d.kind !== SyntaxKind.Identifier), getIsDeclarationVisible)) { + return undefined; + } + return { accessibility: SymbolAccessibility.Accessible, aliasesToMakeVisible }; + + function getIsDeclarationVisible(declaration: Declaration) { + if (!isDeclarationVisible(declaration)) { + // Mark the unexported alias as visible if its parent is visible + // because these kind of aliases can be used to name types in declaration file + + const anyImportSyntax = getAnyImportSyntax(declaration); + if ( + anyImportSyntax && + !hasSyntacticModifier(anyImportSyntax, ModifierFlags.Export) && // import clause without export + isDeclarationVisible(anyImportSyntax.parent) + ) { + return addVisibleAlias(declaration, anyImportSyntax); + } + else if ( + isVariableDeclaration(declaration) && isVariableStatement(declaration.parent.parent) && + !hasSyntacticModifier(declaration.parent.parent, ModifierFlags.Export) && // unexported variable statement + isDeclarationVisible(declaration.parent.parent.parent) + ) { + return addVisibleAlias(declaration, declaration.parent.parent); + } + else if ( + isLateVisibilityPaintedStatement(declaration) // unexported top-level statement + && !hasSyntacticModifier(declaration, ModifierFlags.Export) + && isDeclarationVisible(declaration.parent) + ) { + return addVisibleAlias(declaration, declaration); + } + else if (isBindingElement(declaration)) { + if ( + symbol.flags & SymbolFlags.Alias && isInJSFile(declaration) && declaration.parent?.parent // exported import-like top-level JS require statement + && isVariableDeclaration(declaration.parent.parent) + && declaration.parent.parent.parent?.parent && isVariableStatement(declaration.parent.parent.parent.parent) + && !hasSyntacticModifier(declaration.parent.parent.parent.parent, ModifierFlags.Export) + && declaration.parent.parent.parent.parent.parent // check if the thing containing the variable statement is visible (ie, the file) + && isDeclarationVisible(declaration.parent.parent.parent.parent.parent) + ) { + return addVisibleAlias(declaration, declaration.parent.parent.parent.parent); + } + else if (symbol.flags & SymbolFlags.BlockScopedVariable) { + const variableStatement = findAncestor(declaration, isVariableStatement)!; + if (hasSyntacticModifier(variableStatement, ModifierFlags.Export)) { + return true; + } + if (!isDeclarationVisible(variableStatement.parent)) { + return false; + } + return addVisibleAlias(declaration, variableStatement); + } + } + + // Declaration is not visible + return false; + } + + return true; + } + + function addVisibleAlias(declaration: Declaration, aliasingStatement: LateVisibilityPaintedStatement) { + // In function "buildTypeDisplay" where we decide whether to write type-alias or serialize types, + // we want to just check if type- alias is accessible or not but we don't care about emitting those alias at that time + // since we will do the emitting later in trackSymbol. + if (shouldComputeAliasToMakeVisible) { + getNodeLinks(declaration).isVisible = true; + aliasesToMakeVisible = appendIfUnique(aliasesToMakeVisible, aliasingStatement); + } + return true; + } + } + + function getMeaningOfEntityNameReference(entityName: EntityNameOrEntityNameExpression): SymbolFlags { + // get symbol of the first identifier of the entityName + let meaning: SymbolFlags; + if ( + entityName.parent.kind === SyntaxKind.TypeQuery || + entityName.parent.kind === SyntaxKind.ExpressionWithTypeArguments && !isPartOfTypeNode(entityName.parent) || + entityName.parent.kind === SyntaxKind.ComputedPropertyName || + entityName.parent.kind === SyntaxKind.TypePredicate && (entityName.parent as TypePredicateNode).parameterName === entityName + ) { + // Typeof value + meaning = SymbolFlags.Value | SymbolFlags.ExportValue; + } + else if ( + entityName.kind === SyntaxKind.QualifiedName || entityName.kind === SyntaxKind.PropertyAccessExpression || + entityName.parent.kind === SyntaxKind.ImportEqualsDeclaration || + (entityName.parent.kind === SyntaxKind.QualifiedName && (entityName.parent as QualifiedName).left === entityName) || + (entityName.parent.kind === SyntaxKind.PropertyAccessExpression && (entityName.parent as PropertyAccessExpression).expression === entityName) || + (entityName.parent.kind === SyntaxKind.ElementAccessExpression && (entityName.parent as ElementAccessExpression).expression === entityName) + ) { + // Left identifier from type reference or TypeAlias + // Entity name of the import declaration + meaning = SymbolFlags.Namespace; + } + else { + // Type Reference or TypeAlias entity = Identifier + meaning = SymbolFlags.Type; + } + return meaning; + } + + function isEntityNameVisible(entityName: EntityNameOrEntityNameExpression, enclosingDeclaration: Node, shouldComputeAliasToMakeVisible = true): SymbolVisibilityResult { + const meaning = getMeaningOfEntityNameReference(entityName); + const firstIdentifier = getFirstIdentifier(entityName); + const symbol = resolveName(enclosingDeclaration, firstIdentifier.escapedText, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (symbol && symbol.flags & SymbolFlags.TypeParameter && meaning & SymbolFlags.Type) { + return { accessibility: SymbolAccessibility.Accessible }; + } + if (!symbol && isThisIdentifier(firstIdentifier) && isSymbolAccessible(getSymbolOfDeclaration(getThisContainer(firstIdentifier, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)), firstIdentifier, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility === SymbolAccessibility.Accessible) { + return { accessibility: SymbolAccessibility.Accessible }; + } + + if (!symbol) { + return { + accessibility: SymbolAccessibility.NotResolved, + errorSymbolName: getTextOfNode(firstIdentifier), + errorNode: firstIdentifier, + }; + } + // Verify if the symbol is accessible + return hasVisibleDeclarations(symbol, shouldComputeAliasToMakeVisible) || { + accessibility: SymbolAccessibility.NotAccessible, + errorSymbolName: getTextOfNode(firstIdentifier), + errorNode: firstIdentifier, + }; + } + + function symbolToString(symbol: Symbol, enclosingDeclaration?: Node, meaning?: SymbolFlags, flags: SymbolFormatFlags = SymbolFormatFlags.AllowAnyNodeKind, writer?: EmitTextWriter): string { + let nodeFlags = NodeBuilderFlags.IgnoreErrors; + if (flags & SymbolFormatFlags.UseOnlyExternalAliasing) { + nodeFlags |= NodeBuilderFlags.UseOnlyExternalAliasing; + } + if (flags & SymbolFormatFlags.WriteTypeParametersOrArguments) { + nodeFlags |= NodeBuilderFlags.WriteTypeParametersInQualifiedName; + } + if (flags & SymbolFormatFlags.UseAliasDefinedOutsideCurrentScope) { + nodeFlags |= NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope; + } + if (flags & SymbolFormatFlags.DoNotIncludeSymbolChain) { + nodeFlags |= NodeBuilderFlags.DoNotIncludeSymbolChain; + } + if (flags & SymbolFormatFlags.WriteComputedProps) { + nodeFlags |= NodeBuilderFlags.WriteComputedProps; + } + const builder = flags & SymbolFormatFlags.AllowAnyNodeKind ? nodeBuilder.symbolToNode : nodeBuilder.symbolToEntityName; + return writer ? symbolToStringWorker(writer).getText() : usingSingleLineStringWriter(symbolToStringWorker); + + function symbolToStringWorker(writer: EmitTextWriter) { + const entity = builder(symbol, meaning!, enclosingDeclaration, nodeFlags)!; // TODO: GH#18217 + // add neverAsciiEscape for GH#39027 + const printer = enclosingDeclaration?.kind === SyntaxKind.SourceFile + ? createPrinterWithRemoveCommentsNeverAsciiEscape() + : createPrinterWithRemoveComments(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, entity, /*sourceFile*/ sourceFile, writer); + return writer; + } + } + + function signatureToString(signature: Signature, enclosingDeclaration?: Node, flags = TypeFormatFlags.None, kind?: SignatureKind, writer?: EmitTextWriter): string { + return writer ? signatureToStringWorker(writer).getText() : usingSingleLineStringWriter(signatureToStringWorker); + + function signatureToStringWorker(writer: EmitTextWriter) { + let sigOutput: SyntaxKind; + if (flags & TypeFormatFlags.WriteArrowStyleSignature) { + sigOutput = kind === SignatureKind.Construct ? SyntaxKind.ConstructorType : SyntaxKind.FunctionType; + } + else { + sigOutput = kind === SignatureKind.Construct ? SyntaxKind.ConstructSignature : SyntaxKind.CallSignature; + } + const sig = nodeBuilder.signatureToSignatureDeclaration(signature, sigOutput, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.WriteTypeParametersInQualifiedName); + const printer = createPrinterWithRemoveCommentsOmitTrailingSemicolon(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, sig!, /*sourceFile*/ sourceFile, getTrailingSemicolonDeferringWriter(writer)); // TODO: GH#18217 + return writer; + } + } + + function typeToString(type: Type, enclosingDeclaration?: Node, flags: TypeFormatFlags = TypeFormatFlags.AllowUniqueESSymbolType | TypeFormatFlags.UseAliasDefinedOutsideCurrentScope, writer: EmitTextWriter = createTextWriter("")): string { + const noTruncation = compilerOptions.noErrorTruncation || flags & TypeFormatFlags.NoTruncation; + const typeNode = nodeBuilder.typeToTypeNode(type, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | (noTruncation ? NodeBuilderFlags.NoTruncation : 0)); + if (typeNode === undefined) return Debug.fail("should always get typenode"); + // The unresolved type gets a synthesized comment on `any` to hint to users that it's not a plain `any`. + // Otherwise, we always strip comments out. + const printer = type !== unresolvedType ? createPrinterWithRemoveComments() : createPrinterWithDefaults(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, typeNode, /*sourceFile*/ sourceFile, writer); + const result = writer.getText(); + + const maxLength = noTruncation ? noTruncationMaximumTruncationLength * 2 : defaultMaximumTruncationLength * 2; + if (maxLength && result && result.length >= maxLength) { + return result.substr(0, maxLength - "...".length) + "..."; + } + return result; + } + + function getTypeNamesForErrorDisplay(left: Type, right: Type): [string, string] { + let leftStr = symbolValueDeclarationIsContextSensitive(left.symbol) ? typeToString(left, left.symbol.valueDeclaration) : typeToString(left); + let rightStr = symbolValueDeclarationIsContextSensitive(right.symbol) ? typeToString(right, right.symbol.valueDeclaration) : typeToString(right); + if (leftStr === rightStr) { + leftStr = getTypeNameForErrorDisplay(left); + rightStr = getTypeNameForErrorDisplay(right); + } + return [leftStr, rightStr]; + } + + function getTypeNameForErrorDisplay(type: Type) { + return typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.UseFullyQualifiedType); + } + + function symbolValueDeclarationIsContextSensitive(symbol: Symbol): boolean { + return symbol && !!symbol.valueDeclaration && isExpression(symbol.valueDeclaration) && !isContextSensitive(symbol.valueDeclaration); + } + + function toNodeBuilderFlags(flags = TypeFormatFlags.None): NodeBuilderFlags { + return flags & TypeFormatFlags.NodeBuilderFlagsMask; + } + + function isClassInstanceSide(type: Type) { + return !!type.symbol && !!(type.symbol.flags & SymbolFlags.Class) && (type === getDeclaredTypeOfClassOrInterface(type.symbol) || (!!(type.flags & TypeFlags.Object) && !!(getObjectFlags(type) & ObjectFlags.IsClassInstanceClone))); + } + /** + * Same as getTypeFromTypeNode, but for use in createNodeBuilder + * Inside createNodeBuilder we shadow getTypeFromTypeNode to make sure anyone using this function will call the local version that does type mapping if appropriate + * This function is used to still be able to call the original getTypeFromTypeNode from the local scope version of getTypeFromTypeNode + */ + function getTypeFromTypeNodeWithoutContext(node: TypeNode) { + return getTypeFromTypeNode(node); + } + function createNodeBuilder() { + return { + typeToTypeNode: (type: Type, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeToTypeNodeHelper(type, context)), + typePredicateToTypePredicateNode: (typePredicate: TypePredicate, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typePredicateToTypePredicateNodeHelper(typePredicate, context)), + expressionOrTypeToTypeNode: (expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => expressionOrTypeToTypeNode(context, expr, type, addUndefined)), + serializeTypeForDeclaration: (declaration: Declaration, type: Type, symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => serializeTypeForDeclaration(context, declaration, type, symbol)), + serializeReturnTypeForSignature: (signature: Signature, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => serializeReturnTypeForSignature(context, signature)), + indexInfoToIndexSignatureDeclaration: (indexInfo: IndexInfo, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => indexInfoToIndexSignatureDeclarationHelper(indexInfo, context, /*typeNode*/ undefined)), + signatureToSignatureDeclaration: (signature: Signature, kind: SignatureDeclaration["kind"], enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => signatureToSignatureDeclarationHelper(signature, kind, context)), + symbolToEntityName: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToName(symbol, context, meaning, /*expectsIdentifier*/ false)), + symbolToExpression: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToExpression(symbol, context, meaning)), + symbolToTypeParameterDeclarations: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParametersToTypeParameterDeclarations(symbol, context)), + symbolToParameterDeclaration: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToParameterDeclaration(symbol, context)), + typeParameterToDeclaration: (parameter: TypeParameter, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParameterToDeclaration(parameter, context)), + symbolTableToDeclarationStatements: (symbolTable: SymbolTable, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolTableToDeclarationStatements(symbolTable, context)), + symbolToNode: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToNode(symbol, context, meaning)), + }; + + function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes?: false): Type; + function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes: true): Type | undefined; + function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes?: boolean): Type | undefined { + const type = getTypeFromTypeNodeWithoutContext(node); + if (!context.mapper) return type; + + const mappedType = instantiateType(type, context.mapper); + return noMappedTypes && mappedType !== type ? undefined : mappedType; + } + + /** + * Unlike the utilities `setTextRange`, this checks if the `location` we're trying to set on `range` is within the + * same file as the active context. If not, the range is not applied. This prevents us from copying ranges across files, + * which will confuse the node printer (as it assumes all node ranges are within the current file). + * Additionally, if `range` _isn't synthetic_, or isn't in the current file, it will _copy_ it to _remove_ its' position + * information. + * + * It also calls `setOriginalNode` to setup a `.original` pointer, since you basically *always* want these in the node builder. + */ + function setTextRange(context: NodeBuilderContext, range: T, location: Node | undefined): T { + if (!nodeIsSynthesized(range) || !(range.flags & NodeFlags.Synthesized) || !context.enclosingFile || context.enclosingFile !== getSourceFileOfNode(getOriginalNode(range))) { + range = factory.cloneNode(range); // if `range` is synthesized or originates in another file, copy it so it definitely has synthetic positions + } + if (range === location) return range; + if (!location) { + return range; + } + if (!context.enclosingFile || context.enclosingFile !== getSourceFileOfNode(getOriginalNode(location))) { + return setOriginalNode(range, location); // if `location` is from another file, only set/update original pointer, and not positions, since copying text across files isn't supported by the emitter + } + return setTextRangeWorker(setOriginalNode(range, location), location); + } + + /** + * Same as expressionOrTypeToTypeNodeHelper, but also checks if the expression can be syntactically typed. + */ + function expressionOrTypeToTypeNode(context: NodeBuilderContext, expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean) { + const oldFlags = context.flags; + if (expr && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) { + syntacticNodeBuilder.serializeTypeOfExpression(expr, context, addUndefined); + } + context.flags |= NodeBuilderFlags.NoSyntacticPrinter; + const result = expressionOrTypeToTypeNodeHelper(context, expr, type, addUndefined); + context.flags = oldFlags; + return result; + } + function expressionOrTypeToTypeNodeHelper(context: NodeBuilderContext, expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean) { + if (expr) { + const typeNode = isAssertionExpression(expr) ? expr.type + : isJSDocTypeAssertion(expr) ? getJSDocTypeAssertionType(expr) + : undefined; + if (typeNode && !isConstTypeReference(typeNode)) { + const result = tryReuseExistingTypeNode(context, typeNode, type, expr.parent, addUndefined); + if (result) { + return result; + } + } + } + + if (addUndefined) { + type = getOptionalType(type); + } + + return typeToTypeNodeHelper(type, context); + } + + function tryReuseExistingTypeNode( + context: NodeBuilderContext, + typeNode: TypeNode, + type: Type, + host: Node, + addUndefined?: boolean, + ) { + const originalType = type; + if (addUndefined) { + type = getOptionalType(type); + } + const clone = tryReuseExistingNonParameterTypeNode(context, typeNode, type, host); + if (clone) { + if (addUndefined && !someType(getTypeFromTypeNode(context, typeNode), t => !!(t.flags & TypeFlags.Undefined))) { + return factory.createUnionTypeNode([clone, factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); + } + return clone; + } + if (addUndefined && originalType !== type) { + const cloneMissingUndefined = tryReuseExistingNonParameterTypeNode(context, typeNode, originalType, host); + if (cloneMissingUndefined) { + return factory.createUnionTypeNode([cloneMissingUndefined, factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); + } + } + return undefined; + } + + function tryReuseExistingNonParameterTypeNode( + context: NodeBuilderContext, + existing: TypeNode, + type: Type, + host = context.enclosingDeclaration, + annotationType = getTypeFromTypeNode(context, existing, /*noMappedTypes*/ true), + ) { + if (annotationType && typeNodeIsEquivalentToType(host, type, annotationType) && existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing, type)) { + const result = tryReuseExistingTypeNodeHelper(context, existing); + if (result) { + return result; + } + } + return undefined; + } + + function symbolToNode(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags) { + if (context.flags & NodeBuilderFlags.WriteComputedProps) { + if (symbol.valueDeclaration) { + const name = getNameOfDeclaration(symbol.valueDeclaration); + if (name && isComputedPropertyName(name)) return name; + } + const nameType = getSymbolLinks(symbol).nameType; + if (nameType && nameType.flags & (TypeFlags.EnumLiteral | TypeFlags.UniqueESSymbol)) { + context.enclosingDeclaration = nameType.symbol.valueDeclaration; + return factory.createComputedPropertyName(symbolToExpression(nameType.symbol, context, meaning)); + } + } + return symbolToExpression(symbol, context, meaning); + } + + function withContext(enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, tracker: SymbolTracker | undefined, cb: (context: NodeBuilderContext) => T): T | undefined { + const moduleResolverHost = tracker?.trackSymbol ? tracker.moduleResolverHost : + flags! & NodeBuilderFlags.DoNotIncludeSymbolChain ? createBasicNodeBuilderModuleSpecifierResolutionHost(host) : + undefined; + const context: NodeBuilderContext = { + enclosingDeclaration, + enclosingFile: enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration), + flags: flags || NodeBuilderFlags.None, + tracker: undefined!, + encounteredError: false, + reportedDiagnostic: false, + visitedTypes: undefined, + symbolDepth: undefined, + inferTypeParameters: undefined, + approximateLength: 0, + trackedSymbols: undefined, + bundled: !!compilerOptions.outFile && !!enclosingDeclaration && isExternalOrCommonJsModule(getSourceFileOfNode(enclosingDeclaration)), + truncating: false, + usedSymbolNames: undefined, + remappedSymbolNames: undefined, + remappedSymbolReferences: undefined, + reverseMappedStack: undefined, + mustCreateTypeParameterSymbolList: true, + typeParameterSymbolList: undefined, + mustCreateTypeParametersNamesLookups: true, + typeParameterNames: undefined, + typeParameterNamesByText: undefined, + typeParameterNamesByTextNextNameCount: undefined, + mapper: undefined, + }; + context.tracker = new SymbolTrackerImpl(context, tracker, moduleResolverHost); + const resultingNode = cb(context); + if (context.truncating && context.flags & NodeBuilderFlags.NoTruncation) { + context.tracker.reportTruncationError(); + } + return context.encounteredError ? undefined : resultingNode; + } + + function checkTruncationLength(context: NodeBuilderContext): boolean { + if (context.truncating) return context.truncating; + return context.truncating = context.approximateLength > ((context.flags & NodeBuilderFlags.NoTruncation) ? noTruncationMaximumTruncationLength : defaultMaximumTruncationLength); + } + + function typeToTypeNodeHelper(type: Type, context: NodeBuilderContext): TypeNode { + const savedFlags = context.flags; + const typeNode = typeToTypeNodeWorker(type, context); + context.flags = savedFlags; + return typeNode; + } + + function typeToTypeNodeWorker(type: Type, context: NodeBuilderContext): TypeNode { + if (cancellationToken && cancellationToken.throwIfCancellationRequested) { + cancellationToken.throwIfCancellationRequested(); + } + const inTypeAlias = context.flags & NodeBuilderFlags.InTypeAlias; + context.flags &= ~NodeBuilderFlags.InTypeAlias; + + if (!type) { + if (!(context.flags & NodeBuilderFlags.AllowEmptyUnionOrIntersection)) { + context.encounteredError = true; + return undefined!; // TODO: GH#18217 + } + context.approximateLength += 3; + return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + + if (!(context.flags & NodeBuilderFlags.NoTypeReduction)) { + type = getReducedType(type); + } + + if (type.flags & TypeFlags.Any) { + if (type.aliasSymbol) { + return factory.createTypeReferenceNode(symbolToEntityNameNode(type.aliasSymbol), mapToTypeNodes(type.aliasTypeArguments, context)); + } + if (type === unresolvedType) { + return addSyntheticLeadingComment(factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), SyntaxKind.MultiLineCommentTrivia, "unresolved"); + } + context.approximateLength += 3; + return factory.createKeywordTypeNode(type === intrinsicMarkerType ? SyntaxKind.IntrinsicKeyword : SyntaxKind.AnyKeyword); + } + if (type.flags & TypeFlags.Unknown) { + return factory.createKeywordTypeNode(SyntaxKind.UnknownKeyword); + } + if (type.flags & TypeFlags.String) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.StringKeyword); + } + if (type.flags & TypeFlags.Number) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.NumberKeyword); + } + if (type.flags & TypeFlags.BigInt) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.BigIntKeyword); + } + if (type.flags & TypeFlags.Boolean && !type.aliasSymbol) { + context.approximateLength += 7; + return factory.createKeywordTypeNode(SyntaxKind.BooleanKeyword); + } + if (type.flags & TypeFlags.EnumLike) { + if (type.symbol.flags & SymbolFlags.EnumMember) { + const parentSymbol = getParentOfSymbol(type.symbol)!; + const parentName = symbolToTypeNode(parentSymbol, context, SymbolFlags.Type); + if (getDeclaredTypeOfSymbol(parentSymbol) === type) { + return parentName; + } + const memberName = symbolName(type.symbol); + if (isIdentifierText(memberName, ScriptTarget.ES5)) { + return appendReferenceToType( + parentName as TypeReferenceNode | ImportTypeNode, + factory.createTypeReferenceNode(memberName, /*typeArguments*/ undefined), + ); + } + if (isImportTypeNode(parentName)) { + (parentName as any).isTypeOf = true; // mutably update, node is freshly manufactured anyhow + return factory.createIndexedAccessTypeNode(parentName, factory.createLiteralTypeNode(factory.createStringLiteral(memberName))); + } + else if (isTypeReferenceNode(parentName)) { + return factory.createIndexedAccessTypeNode(factory.createTypeQueryNode(parentName.typeName), factory.createLiteralTypeNode(factory.createStringLiteral(memberName))); + } + else { + return Debug.fail("Unhandled type node kind returned from `symbolToTypeNode`."); + } + } + return symbolToTypeNode(type.symbol, context, SymbolFlags.Type); + } + if (type.flags & TypeFlags.StringLiteral) { + context.approximateLength += (type as StringLiteralType).value.length + 2; + return factory.createLiteralTypeNode(setEmitFlags(factory.createStringLiteral((type as StringLiteralType).value, !!(context.flags & NodeBuilderFlags.UseSingleQuotesForStringLiteralType)), EmitFlags.NoAsciiEscaping)); + } + if (type.flags & TypeFlags.NumberLiteral) { + const value = (type as NumberLiteralType).value; + context.approximateLength += ("" + value).length; + return factory.createLiteralTypeNode(value < 0 ? factory.createPrefixUnaryExpression(SyntaxKind.MinusToken, factory.createNumericLiteral(-value)) : factory.createNumericLiteral(value)); + } + if (type.flags & TypeFlags.BigIntLiteral) { + context.approximateLength += (pseudoBigIntToString((type as BigIntLiteralType).value).length) + 1; + return factory.createLiteralTypeNode(factory.createBigIntLiteral((type as BigIntLiteralType).value)); + } + if (type.flags & TypeFlags.BooleanLiteral) { + context.approximateLength += (type as IntrinsicType).intrinsicName.length; + return factory.createLiteralTypeNode((type as IntrinsicType).intrinsicName === "true" ? factory.createTrue() : factory.createFalse()); + } + if (type.flags & TypeFlags.UniqueESSymbol) { + if (!(context.flags & NodeBuilderFlags.AllowUniqueESSymbolType)) { + if (isValueSymbolAccessible(type.symbol, context.enclosingDeclaration)) { + context.approximateLength += 6; + return symbolToTypeNode(type.symbol, context, SymbolFlags.Value); + } + if (context.tracker.reportInaccessibleUniqueSymbolError) { + context.tracker.reportInaccessibleUniqueSymbolError(); + } + } + context.approximateLength += 13; + return factory.createTypeOperatorNode(SyntaxKind.UniqueKeyword, factory.createKeywordTypeNode(SyntaxKind.SymbolKeyword)); + } + if (type.flags & TypeFlags.Void) { + context.approximateLength += 4; + return factory.createKeywordTypeNode(SyntaxKind.VoidKeyword); + } + if (type.flags & TypeFlags.Undefined) { + context.approximateLength += 9; + return factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword); + } + if (type.flags & TypeFlags.Null) { + context.approximateLength += 4; + return factory.createLiteralTypeNode(factory.createNull()); + } + if (type.flags & TypeFlags.Never) { + context.approximateLength += 5; + return factory.createKeywordTypeNode(SyntaxKind.NeverKeyword); + } + if (type.flags & TypeFlags.ESSymbol) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.SymbolKeyword); + } + if (type.flags & TypeFlags.NonPrimitive) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.ObjectKeyword); + } + if (isThisTypeParameter(type)) { + if (context.flags & NodeBuilderFlags.InObjectTypeLiteral) { + if (!context.encounteredError && !(context.flags & NodeBuilderFlags.AllowThisInObjectLiteral)) { + context.encounteredError = true; + } + context.tracker.reportInaccessibleThisError?.(); + } + context.approximateLength += 4; + return factory.createThisTypeNode(); + } + + if (!inTypeAlias && type.aliasSymbol && (context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope || isTypeSymbolAccessible(type.aliasSymbol, context.enclosingDeclaration))) { + const typeArgumentNodes = mapToTypeNodes(type.aliasTypeArguments, context); + if (isReservedMemberName(type.aliasSymbol.escapedName) && !(type.aliasSymbol.flags & SymbolFlags.Class)) return factory.createTypeReferenceNode(factory.createIdentifier(""), typeArgumentNodes); + if (length(typeArgumentNodes) === 1 && type.aliasSymbol === globalArrayType.symbol) { + return factory.createArrayTypeNode(typeArgumentNodes![0]); + } + return symbolToTypeNode(type.aliasSymbol, context, SymbolFlags.Type, typeArgumentNodes); + } + + const objectFlags = getObjectFlags(type); + + if (objectFlags & ObjectFlags.Reference) { + Debug.assert(!!(type.flags & TypeFlags.Object)); + return (type as TypeReference).node ? visitAndTransformType(type as TypeReference, typeReferenceToTypeNode) : typeReferenceToTypeNode(type as TypeReference); + } + if (type.flags & TypeFlags.TypeParameter || objectFlags & ObjectFlags.ClassOrInterface) { + if (type.flags & TypeFlags.TypeParameter && contains(context.inferTypeParameters, type)) { + context.approximateLength += symbolName(type.symbol).length + 6; + let constraintNode: TypeNode | undefined; + const constraint = getConstraintOfTypeParameter(type as TypeParameter); + if (constraint) { + // If the infer type has a constraint that is not the same as the constraint + // we would have normally inferred based on context, we emit the constraint + // using `infer T extends ?`. We omit inferred constraints from type references + // as they may be elided. + const inferredConstraint = getInferredTypeParameterConstraint(type as TypeParameter, /*omitTypeReferences*/ true); + if (!(inferredConstraint && isTypeIdenticalTo(constraint, inferredConstraint))) { + context.approximateLength += 9; + constraintNode = constraint && typeToTypeNodeHelper(constraint, context); + } + } + return factory.createInferTypeNode(typeParameterToDeclarationWithConstraint(type as TypeParameter, context, constraintNode)); + } + if ( + context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && + type.flags & TypeFlags.TypeParameter + ) { + const name = typeParameterToName(type, context); + context.approximateLength += idText(name).length; + return factory.createTypeReferenceNode(factory.createIdentifier(idText(name)), /*typeArguments*/ undefined); + } + // Ignore constraint/default when creating a usage (as opposed to declaration) of a type parameter. + if (type.symbol) { + return symbolToTypeNode(type.symbol, context, SymbolFlags.Type); + } + const name = (type === markerSuperTypeForCheck || type === markerSubTypeForCheck) && varianceTypeParameter && varianceTypeParameter.symbol ? + (type === markerSubTypeForCheck ? "sub-" : "super-") + symbolName(varianceTypeParameter.symbol) : "?"; + return factory.createTypeReferenceNode(factory.createIdentifier(name), /*typeArguments*/ undefined); + } + if (type.flags & TypeFlags.Union && (type as UnionType).origin) { + type = (type as UnionType).origin!; + } + if (type.flags & (TypeFlags.Union | TypeFlags.Intersection)) { + const types = type.flags & TypeFlags.Union ? formatUnionTypes((type as UnionType).types) : (type as IntersectionType).types; + if (length(types) === 1) { + return typeToTypeNodeHelper(types[0], context); + } + const typeNodes = mapToTypeNodes(types, context, /*isBareList*/ true); + if (typeNodes && typeNodes.length > 0) { + return type.flags & TypeFlags.Union ? factory.createUnionTypeNode(typeNodes) : factory.createIntersectionTypeNode(typeNodes); + } + else { + if (!context.encounteredError && !(context.flags & NodeBuilderFlags.AllowEmptyUnionOrIntersection)) { + context.encounteredError = true; + } + return undefined!; // TODO: GH#18217 + } + } + if (objectFlags & (ObjectFlags.Anonymous | ObjectFlags.Mapped)) { + Debug.assert(!!(type.flags & TypeFlags.Object)); + // The type is an object literal type. + return createAnonymousTypeNode(type as ObjectType); + } + if (type.flags & TypeFlags.Index) { + const indexedType = (type as IndexType).type; + context.approximateLength += 6; + const indexTypeNode = typeToTypeNodeHelper(indexedType, context); + return factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, indexTypeNode); + } + if (type.flags & TypeFlags.TemplateLiteral) { + const texts = (type as TemplateLiteralType).texts; + const types = (type as TemplateLiteralType).types; + const templateHead = factory.createTemplateHead(texts[0]); + const templateSpans = factory.createNodeArray( + map(types, (t, i) => + factory.createTemplateLiteralTypeSpan( + typeToTypeNodeHelper(t, context), + (i < types.length - 1 ? factory.createTemplateMiddle : factory.createTemplateTail)(texts[i + 1]), + )), + ); + context.approximateLength += 2; + return factory.createTemplateLiteralType(templateHead, templateSpans); + } + if (type.flags & TypeFlags.StringMapping) { + const typeNode = typeToTypeNodeHelper((type as StringMappingType).type, context); + return symbolToTypeNode((type as StringMappingType).symbol, context, SymbolFlags.Type, [typeNode]); + } + if (type.flags & TypeFlags.IndexedAccess) { + const objectTypeNode = typeToTypeNodeHelper((type as IndexedAccessType).objectType, context); + const indexTypeNode = typeToTypeNodeHelper((type as IndexedAccessType).indexType, context); + context.approximateLength += 2; + return factory.createIndexedAccessTypeNode(objectTypeNode, indexTypeNode); + } + if (type.flags & TypeFlags.Conditional) { + return visitAndTransformType(type, type => conditionalTypeToTypeNode(type as ConditionalType)); + } + if (type.flags & TypeFlags.Substitution) { + const typeNode = typeToTypeNodeHelper((type as SubstitutionType).baseType, context); + const noInferSymbol = isNoInferType(type) && getGlobalTypeSymbol("NoInfer" as __String, /*reportErrors*/ false); + return noInferSymbol ? symbolToTypeNode(noInferSymbol, context, SymbolFlags.Type, [typeNode]) : typeNode; + } + + return Debug.fail("Should be unreachable."); + + function conditionalTypeToTypeNode(type: ConditionalType) { + const checkTypeNode = typeToTypeNodeHelper(type.checkType, context); + context.approximateLength += 15; + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && type.root.isDistributive && !(type.checkType.flags & TypeFlags.TypeParameter)) { + const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); + const name = typeParameterToName(newParam, context); + const newTypeVariable = factory.createTypeReferenceNode(name); + context.approximateLength += 37; // 15 each for two added conditionals, 7 for an added infer type + const newMapper = prependTypeMapping(type.root.checkType, newParam, type.mapper); + const saveInferTypeParameters = context.inferTypeParameters; + context.inferTypeParameters = type.root.inferTypeParameters; + const extendsTypeNode = typeToTypeNodeHelper(instantiateType(type.root.extendsType, newMapper), context); + context.inferTypeParameters = saveInferTypeParameters; + const trueTypeNode = typeToTypeNodeOrCircularityElision(instantiateType(getTypeFromTypeNode(context, type.root.node.trueType), newMapper)); + const falseTypeNode = typeToTypeNodeOrCircularityElision(instantiateType(getTypeFromTypeNode(context, type.root.node.falseType), newMapper)); + + // outermost conditional makes `T` a type parameter, allowing the inner conditionals to be distributive + // second conditional makes `T` have `T & checkType` substitution, so it is correctly usable as the checkType + // inner conditional runs the check the user provided on the check type (distributively) and returns the result + // checkType extends infer T ? T extends checkType ? T extends extendsType ? trueType : falseType : never : never; + // this is potentially simplifiable to + // checkType extends infer T ? T extends checkType & extendsType ? trueType : falseType : never; + // but that may confuse users who read the output more. + // On the other hand, + // checkType extends infer T extends checkType ? T extends extendsType ? trueType : falseType : never; + // may also work with `infer ... extends ...` in, but would produce declarations only compatible with the latest TS. + return factory.createConditionalTypeNode( + checkTypeNode, + factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable.typeName) as Identifier)), + factory.createConditionalTypeNode( + factory.createTypeReferenceNode(factory.cloneNode(name)), + typeToTypeNodeHelper(type.checkType, context), + factory.createConditionalTypeNode(newTypeVariable, extendsTypeNode, trueTypeNode, falseTypeNode), + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ), + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ); + } + const saveInferTypeParameters = context.inferTypeParameters; + context.inferTypeParameters = type.root.inferTypeParameters; + const extendsTypeNode = typeToTypeNodeHelper(type.extendsType, context); + context.inferTypeParameters = saveInferTypeParameters; + const trueTypeNode = typeToTypeNodeOrCircularityElision(getTrueTypeFromConditionalType(type)); + const falseTypeNode = typeToTypeNodeOrCircularityElision(getFalseTypeFromConditionalType(type)); + return factory.createConditionalTypeNode(checkTypeNode, extendsTypeNode, trueTypeNode, falseTypeNode); + } + + function typeToTypeNodeOrCircularityElision(type: Type) { + if (type.flags & TypeFlags.Union) { + if (context.visitedTypes?.has(getTypeId(type))) { + if (!(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier)) { + context.encounteredError = true; + context.tracker?.reportCyclicStructureError?.(); + } + return createElidedInformationPlaceholder(context); + } + return visitAndTransformType(type, type => typeToTypeNodeHelper(type, context)); + } + return typeToTypeNodeHelper(type, context); + } + + function isMappedTypeHomomorphic(type: MappedType) { + return !!getHomomorphicTypeVariable(type); + } + + function isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type: MappedType) { + return !!type.target && isMappedTypeHomomorphic(type.target as MappedType) && !isMappedTypeHomomorphic(type); + } + + function createMappedTypeNodeFromType(type: MappedType) { + Debug.assert(!!(type.flags & TypeFlags.Object)); + const readonlyToken = type.declaration.readonlyToken ? factory.createToken(type.declaration.readonlyToken.kind) as ReadonlyKeyword | PlusToken | MinusToken : undefined; + const questionToken = type.declaration.questionToken ? factory.createToken(type.declaration.questionToken.kind) as QuestionToken | PlusToken | MinusToken : undefined; + let appropriateConstraintTypeNode: TypeNode; + let newTypeVariable: TypeReferenceNode | undefined; + // If the mapped type isn't `keyof` constraint-declared, _but_ still has modifiers preserved, and its naive instantiation won't preserve modifiers because its constraint isn't `keyof` constrained, we have work to do + const needsModifierPreservingWrapper = !isMappedTypeWithKeyofConstraintDeclaration(type) + && !(getModifiersTypeFromMappedType(type).flags & TypeFlags.Unknown) + && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams + && !(getConstraintTypeFromMappedType(type).flags & TypeFlags.TypeParameter && getConstraintOfTypeParameter(getConstraintTypeFromMappedType(type))?.flags! & TypeFlags.Index); + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // We have a { [P in keyof T]: X } + // We do this to ensure we retain the toplevel keyof-ness of the type which may be lost due to keyof distribution during `getConstraintTypeFromMappedType` + if (isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type) && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { + const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); + const name = typeParameterToName(newParam, context); + newTypeVariable = factory.createTypeReferenceNode(name); + } + appropriateConstraintTypeNode = factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, newTypeVariable || typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context)); + } + else if (needsModifierPreservingWrapper) { + // So, step 1: new type variable + const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); + const name = typeParameterToName(newParam, context); + newTypeVariable = factory.createTypeReferenceNode(name); + // step 2: make that new type variable itself the constraint node, making the mapped type `{[K in T_1]: Template}` + appropriateConstraintTypeNode = newTypeVariable; + } + else { + appropriateConstraintTypeNode = typeToTypeNodeHelper(getConstraintTypeFromMappedType(type), context); + } + const typeParameterNode = typeParameterToDeclarationWithConstraint(getTypeParameterFromMappedType(type), context, appropriateConstraintTypeNode); + const nameTypeNode = type.declaration.nameType ? typeToTypeNodeHelper(getNameTypeFromMappedType(type)!, context) : undefined; + const templateTypeNode = typeToTypeNodeHelper(removeMissingType(getTemplateTypeFromMappedType(type), !!(getMappedTypeModifiers(type) & MappedTypeModifiers.IncludeOptional)), context); + const mappedTypeNode = factory.createMappedTypeNode(readonlyToken, typeParameterNode, nameTypeNode, questionToken, templateTypeNode, /*members*/ undefined); + context.approximateLength += 10; + const result = setEmitFlags(mappedTypeNode, EmitFlags.SingleLine); + if (isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type) && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { + // homomorphic mapped type with a non-homomorphic naive inlining + // wrap it with a conditional like `SomeModifiersType extends infer U ? {..the mapped type...} : never` to ensure the resulting + // type stays homomorphic + const originalConstraint = instantiateType(getConstraintOfTypeParameter(getTypeFromTypeNode(context, (type.declaration.typeParameter.constraint! as TypeOperatorNode).type) as TypeParameter) || unknownType, type.mapper); + return factory.createConditionalTypeNode( + typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context), + factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable!.typeName) as Identifier, originalConstraint.flags & TypeFlags.Unknown ? undefined : typeToTypeNodeHelper(originalConstraint, context))), + result, + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ); + } + else if (needsModifierPreservingWrapper) { + // and step 3: once the mapped type is reconstructed, create a `ConstraintType extends infer T_1 extends keyof ModifiersType ? {[K in T_1]: Template} : never` + // subtly different from the `keyof` constraint case, by including the `keyof` constraint on the `infer` type parameter, it doesn't rely on the constraint type being itself + // constrained to a `keyof` type to preserve its modifier-preserving behavior. This is all basically because we preserve modifiers for a wider set of mapped types than + // just homomorphic ones. + return factory.createConditionalTypeNode( + typeToTypeNodeHelper(getConstraintTypeFromMappedType(type), context), + factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable!.typeName) as Identifier, factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context)))), + result, + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ); + } + return result; + } + + function createAnonymousTypeNode(type: ObjectType): TypeNode { + const typeId = type.id; + const symbol = type.symbol; + if (symbol) { + const isInstantiationExpressionType = !!(getObjectFlags(type) & ObjectFlags.InstantiationExpressionType); + if (isInstantiationExpressionType) { + const instantiationExpressionType = type as InstantiationExpressionType; + const existing = instantiationExpressionType.node; + if (isTypeQueryNode(existing)) { + const typeNode = tryReuseExistingNonParameterTypeNode(context, existing, type); + if (typeNode) { + return typeNode; + } + } + if (context.visitedTypes?.has(typeId)) { + return createElidedInformationPlaceholder(context); + } + return visitAndTransformType(type, createTypeNodeFromObjectType); + } + const isInstanceType = isClassInstanceSide(type) ? SymbolFlags.Type : SymbolFlags.Value; + if (isJSConstructor(symbol.valueDeclaration)) { + // Instance and static types share the same symbol; only add 'typeof' for the static side. + return symbolToTypeNode(symbol, context, isInstanceType); + } + // Always use 'typeof T' for type of class, enum, and module objects + else if ( + symbol.flags & SymbolFlags.Class + && !getBaseTypeVariableOfClass(symbol) + && !(symbol.valueDeclaration && isClassLike(symbol.valueDeclaration) && context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral && (!isClassDeclaration(symbol.valueDeclaration) || isSymbolAccessible(symbol, context.enclosingDeclaration, isInstanceType, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible)) || + symbol.flags & (SymbolFlags.Enum | SymbolFlags.ValueModule) || + shouldWriteTypeOfFunctionSymbol() + ) { + return symbolToTypeNode(symbol, context, isInstanceType); + } + else if (context.visitedTypes?.has(typeId)) { + // If type is an anonymous type literal in a type alias declaration, use type alias name + const typeAlias = getTypeAliasForTypeLiteral(type); + if (typeAlias) { + // The specified symbol flags need to be reinterpreted as type flags + return symbolToTypeNode(typeAlias, context, SymbolFlags.Type); + } + else { + return createElidedInformationPlaceholder(context); + } + } + else { + return visitAndTransformType(type, createTypeNodeFromObjectType); + } + } + else { + // Anonymous types without a symbol are never circular. + return createTypeNodeFromObjectType(type); + } + function shouldWriteTypeOfFunctionSymbol() { + const isStaticMethodSymbol = !!(symbol.flags & SymbolFlags.Method) && // typeof static method + some(symbol.declarations, declaration => isStatic(declaration)); + const isNonLocalFunctionSymbol = !!(symbol.flags & SymbolFlags.Function) && + (symbol.parent || // is exported function symbol + forEach(symbol.declarations, declaration => declaration.parent.kind === SyntaxKind.SourceFile || declaration.parent.kind === SyntaxKind.ModuleBlock)); + if (isStaticMethodSymbol || isNonLocalFunctionSymbol) { + // typeof is allowed only for static/non local functions + return (!!(context.flags & NodeBuilderFlags.UseTypeOfFunction) || (context.visitedTypes?.has(typeId))) && // it is type of the symbol uses itself recursively + (!(context.flags & NodeBuilderFlags.UseStructuralFallback) || isValueSymbolAccessible(symbol, context.enclosingDeclaration)); // And the build is going to succeed without visibility error or there is no structural fallback allowed + } + } + } + + function visitAndTransformType(type: T, transform: (type: T) => TypeNode) { + const typeId = type.id; + const isConstructorObject = getObjectFlags(type) & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & SymbolFlags.Class; + const id = getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference & T).node ? "N" + getNodeId((type as TypeReference & T).node!) : + type.flags & TypeFlags.Conditional ? "N" + getNodeId((type as ConditionalType & T).root.node) : + type.symbol ? (isConstructorObject ? "+" : "") + getSymbolId(type.symbol) : + undefined; + // Since instantiations of the same anonymous type have the same symbol, tracking symbols instead + // of types allows us to catch circular references to instantiations of the same anonymous type + if (!context.visitedTypes) { + context.visitedTypes = new Set(); + } + if (id && !context.symbolDepth) { + context.symbolDepth = new Map(); + } + + const links = context.enclosingDeclaration && getNodeLinks(context.enclosingDeclaration); + const key = `${getTypeId(type)}|${context.flags}`; + if (links) { + links.serializedTypes ||= new Map(); + } + const cachedResult = links?.serializedTypes?.get(key); + if (cachedResult) { + // TODO:: check if we instead store late painted statements associated with this? + cachedResult.trackedSymbols?.forEach( + ([symbol, enclosingDeclaration, meaning]) => + context.tracker.trackSymbol( + symbol, + enclosingDeclaration, + meaning, + ), + ); + if (cachedResult.truncating) { + context.truncating = true; + } + context.approximateLength += cachedResult.addedLength; + return deepCloneOrReuseNode(cachedResult.node); + } + + let depth: number | undefined; + if (id) { + depth = context.symbolDepth!.get(id) || 0; + if (depth > 10) { + return createElidedInformationPlaceholder(context); + } + context.symbolDepth!.set(id, depth + 1); + } + context.visitedTypes.add(typeId); + const prevTrackedSymbols = context.trackedSymbols; + context.trackedSymbols = undefined; + const startLength = context.approximateLength; + const result = transform(type); + const addedLength = context.approximateLength - startLength; + if (!context.reportedDiagnostic && !context.encounteredError) { + links?.serializedTypes?.set(key, { + node: result, + truncating: context.truncating, + addedLength, + trackedSymbols: context.trackedSymbols, + }); + } + context.visitedTypes.delete(typeId); + if (id) { + context.symbolDepth!.set(id, depth!); + } + context.trackedSymbols = prevTrackedSymbols; + return result; + + function deepCloneOrReuseNode(node: T): T { + if (!nodeIsSynthesized(node) && getParseTreeNode(node) === node) { + return node; + } + return setTextRange(context, factory.cloneNode(visitEachChildWorker(node, deepCloneOrReuseNode, /*context*/ undefined, deepCloneOrReuseNodes, deepCloneOrReuseNode)), node); + } + + function deepCloneOrReuseNodes( + nodes: NodeArray | undefined, + visitor: Visitor, + test?: (node: Node) => boolean, + start?: number, + count?: number, + ): NodeArray | undefined { + if (nodes && nodes.length === 0) { + // Ensure we explicitly make a copy of an empty array; visitNodes will not do this unless the array has elements, + // which can lead to us reusing the same empty NodeArray more than once within the same AST during type noding. + return setTextRangeWorker(factory.createNodeArray(/*elements*/ undefined, nodes.hasTrailingComma), nodes); + } + return visitNodes(nodes, visitor, test, start, count); + } + } + + function createTypeNodeFromObjectType(type: ObjectType): TypeNode { + if (isGenericMappedType(type) || (type as MappedType).containsError) { + return createMappedTypeNodeFromType(type as MappedType); + } + + const resolved = resolveStructuredTypeMembers(type); + if (!resolved.properties.length && !resolved.indexInfos.length) { + if (!resolved.callSignatures.length && !resolved.constructSignatures.length) { + context.approximateLength += 2; + return setEmitFlags(factory.createTypeLiteralNode(/*members*/ undefined), EmitFlags.SingleLine); + } + + if (resolved.callSignatures.length === 1 && !resolved.constructSignatures.length) { + const signature = resolved.callSignatures[0]; + const signatureNode = signatureToSignatureDeclarationHelper(signature, SyntaxKind.FunctionType, context) as FunctionTypeNode; + return signatureNode; + } + + if (resolved.constructSignatures.length === 1 && !resolved.callSignatures.length) { + const signature = resolved.constructSignatures[0]; + const signatureNode = signatureToSignatureDeclarationHelper(signature, SyntaxKind.ConstructorType, context) as ConstructorTypeNode; + return signatureNode; + } + } + + const abstractSignatures = filter(resolved.constructSignatures, signature => !!(signature.flags & SignatureFlags.Abstract)); + if (some(abstractSignatures)) { + const types = map(abstractSignatures, s => getOrCreateTypeFromSignature(s)); + // count the number of type elements excluding abstract constructors + const typeElementCount = resolved.callSignatures.length + + (resolved.constructSignatures.length - abstractSignatures.length) + + resolved.indexInfos.length + + // exclude `prototype` when writing a class expression as a type literal, as per + // the logic in `createTypeNodesFromResolvedType`. + (context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral ? + countWhere(resolved.properties, p => !(p.flags & SymbolFlags.Prototype)) : + length(resolved.properties)); + // don't include an empty object literal if there were no other static-side + // properties to write, i.e. `abstract class C { }` becomes `abstract new () => {}` + // and not `(abstract new () => {}) & {}` + if (typeElementCount) { + // create a copy of the object type without any abstract construct signatures. + types.push(getResolvedTypeWithoutAbstractConstructSignatures(resolved)); + } + return typeToTypeNodeHelper(getIntersectionType(types), context); + } + + const savedFlags = context.flags; + context.flags |= NodeBuilderFlags.InObjectTypeLiteral; + const members = createTypeNodesFromResolvedType(resolved); + context.flags = savedFlags; + const typeLiteralNode = factory.createTypeLiteralNode(members); + context.approximateLength += 2; + setEmitFlags(typeLiteralNode, (context.flags & NodeBuilderFlags.MultilineObjectLiterals) ? 0 : EmitFlags.SingleLine); + return typeLiteralNode; + } + + function typeReferenceToTypeNode(type: TypeReference) { + let typeArguments: readonly Type[] = getTypeArguments(type); + if (type.target === globalArrayType || type.target === globalReadonlyArrayType) { + if (context.flags & NodeBuilderFlags.WriteArrayAsGenericType) { + const typeArgumentNode = typeToTypeNodeHelper(typeArguments[0], context); + return factory.createTypeReferenceNode(type.target === globalArrayType ? "Array" : "ReadonlyArray", [typeArgumentNode]); + } + const elementType = typeToTypeNodeHelper(typeArguments[0], context); + const arrayType = factory.createArrayTypeNode(elementType); + return type.target === globalArrayType ? arrayType : factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, arrayType); + } + else if (type.target.objectFlags & ObjectFlags.Tuple) { + typeArguments = sameMap(typeArguments, (t, i) => removeMissingType(t, !!((type.target as TupleType).elementFlags[i] & ElementFlags.Optional))); + if (typeArguments.length > 0) { + const arity = getTypeReferenceArity(type); + const tupleConstituentNodes = mapToTypeNodes(typeArguments.slice(0, arity), context); + if (tupleConstituentNodes) { + const { labeledElementDeclarations } = type.target as TupleType; + for (let i = 0; i < tupleConstituentNodes.length; i++) { + const flags = (type.target as TupleType).elementFlags[i]; + const labeledElementDeclaration = labeledElementDeclarations?.[i]; + + if (labeledElementDeclaration) { + tupleConstituentNodes[i] = factory.createNamedTupleMember( + flags & ElementFlags.Variable ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined, + factory.createIdentifier(unescapeLeadingUnderscores(getTupleElementLabel(labeledElementDeclaration))), + flags & ElementFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + flags & ElementFlags.Rest ? factory.createArrayTypeNode(tupleConstituentNodes[i]) : + tupleConstituentNodes[i], + ); + } + else { + tupleConstituentNodes[i] = flags & ElementFlags.Variable ? factory.createRestTypeNode(flags & ElementFlags.Rest ? factory.createArrayTypeNode(tupleConstituentNodes[i]) : tupleConstituentNodes[i]) : + flags & ElementFlags.Optional ? factory.createOptionalTypeNode(tupleConstituentNodes[i]) : + tupleConstituentNodes[i]; + } + } + const tupleTypeNode = setEmitFlags(factory.createTupleTypeNode(tupleConstituentNodes), EmitFlags.SingleLine); + return (type.target as TupleType).readonly ? factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, tupleTypeNode) : tupleTypeNode; + } + } + if (context.encounteredError || (context.flags & NodeBuilderFlags.AllowEmptyTuple)) { + const tupleTypeNode = setEmitFlags(factory.createTupleTypeNode([]), EmitFlags.SingleLine); + return (type.target as TupleType).readonly ? factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, tupleTypeNode) : tupleTypeNode; + } + context.encounteredError = true; + return undefined!; // TODO: GH#18217 + } + else if ( + context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral && + type.symbol.valueDeclaration && + isClassLike(type.symbol.valueDeclaration) && + !isValueSymbolAccessible(type.symbol, context.enclosingDeclaration) + ) { + return createAnonymousTypeNode(type); + } + else { + const outerTypeParameters = type.target.outerTypeParameters; + let i = 0; + let resultType: TypeReferenceNode | ImportTypeNode | undefined; + if (outerTypeParameters) { + const length = outerTypeParameters.length; + while (i < length) { + // Find group of type arguments for type parameters with the same declaring container. + const start = i; + const parent = getParentSymbolOfTypeParameter(outerTypeParameters[i])!; + do { + i++; + } + while (i < length && getParentSymbolOfTypeParameter(outerTypeParameters[i]) === parent); + // When type parameters are their own type arguments for the whole group (i.e. we have + // the default outer type arguments), we don't show the group. + if (!rangeEquals(outerTypeParameters, typeArguments, start, i)) { + const typeArgumentSlice = mapToTypeNodes(typeArguments.slice(start, i), context); + const flags = context.flags; + context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences; + const ref = symbolToTypeNode(parent, context, SymbolFlags.Type, typeArgumentSlice) as TypeReferenceNode | ImportTypeNode; + context.flags = flags; + resultType = !resultType ? ref : appendReferenceToType(resultType, ref as TypeReferenceNode); + } + } + } + let typeArgumentNodes: readonly TypeNode[] | undefined; + if (typeArguments.length > 0) { + const typeParameterCount = (type.target.typeParameters || emptyArray).length; + typeArgumentNodes = mapToTypeNodes(typeArguments.slice(i, typeParameterCount), context); + } + const flags = context.flags; + context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences; + const finalRef = symbolToTypeNode(type.symbol, context, SymbolFlags.Type, typeArgumentNodes); + context.flags = flags; + return !resultType ? finalRef : appendReferenceToType(resultType, finalRef as TypeReferenceNode); + } + } + + function appendReferenceToType(root: TypeReferenceNode | ImportTypeNode, ref: TypeReferenceNode): TypeReferenceNode | ImportTypeNode { + if (isImportTypeNode(root)) { + // first shift type arguments + let typeArguments = root.typeArguments; + let qualifier = root.qualifier; + if (qualifier) { + if (isIdentifier(qualifier)) { + if (typeArguments !== getIdentifierTypeArguments(qualifier)) { + qualifier = setIdentifierTypeArguments(factory.cloneNode(qualifier), typeArguments); + } + } + else { + if (typeArguments !== getIdentifierTypeArguments(qualifier.right)) { + qualifier = factory.updateQualifiedName(qualifier, qualifier.left, setIdentifierTypeArguments(factory.cloneNode(qualifier.right), typeArguments)); + } + } + } + typeArguments = ref.typeArguments; + // then move qualifiers + const ids = getAccessStack(ref); + for (const id of ids) { + qualifier = qualifier ? factory.createQualifiedName(qualifier, id) : id; + } + return factory.updateImportTypeNode( + root, + root.argument, + root.attributes, + qualifier, + typeArguments, + root.isTypeOf, + ); + } + else { + // first shift type arguments + let typeArguments = root.typeArguments; + let typeName = root.typeName; + if (isIdentifier(typeName)) { + if (typeArguments !== getIdentifierTypeArguments(typeName)) { + typeName = setIdentifierTypeArguments(factory.cloneNode(typeName), typeArguments); + } + } + else { + if (typeArguments !== getIdentifierTypeArguments(typeName.right)) { + typeName = factory.updateQualifiedName(typeName, typeName.left, setIdentifierTypeArguments(factory.cloneNode(typeName.right), typeArguments)); + } + } + typeArguments = ref.typeArguments; + // then move qualifiers + const ids = getAccessStack(ref); + for (const id of ids) { + typeName = factory.createQualifiedName(typeName, id); + } + return factory.updateTypeReferenceNode( + root, + typeName, + typeArguments, + ); + } + } + + function getAccessStack(ref: TypeReferenceNode): Identifier[] { + let state = ref.typeName; + const ids = []; + while (!isIdentifier(state)) { + ids.unshift(state.right); + state = state.left; + } + ids.unshift(state); + return ids; + } + + function createTypeNodesFromResolvedType(resolvedType: ResolvedType): TypeElement[] | undefined { + if (checkTruncationLength(context)) { + return [factory.createPropertySignature(/*modifiers*/ undefined, "...", /*questionToken*/ undefined, /*type*/ undefined)]; + } + const typeElements: TypeElement[] = []; + for (const signature of resolvedType.callSignatures) { + typeElements.push(signatureToSignatureDeclarationHelper(signature, SyntaxKind.CallSignature, context) as CallSignatureDeclaration); + } + for (const signature of resolvedType.constructSignatures) { + if (signature.flags & SignatureFlags.Abstract) continue; + typeElements.push(signatureToSignatureDeclarationHelper(signature, SyntaxKind.ConstructSignature, context) as ConstructSignatureDeclaration); + } + for (const info of resolvedType.indexInfos) { + typeElements.push(indexInfoToIndexSignatureDeclarationHelper(info, context, resolvedType.objectFlags & ObjectFlags.ReverseMapped ? createElidedInformationPlaceholder(context) : undefined)); + } + + const properties = resolvedType.properties; + if (!properties) { + return typeElements; + } + + let i = 0; + for (const propertySymbol of properties) { + i++; + if (context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral) { + if (propertySymbol.flags & SymbolFlags.Prototype) { + continue; + } + if (getDeclarationModifierFlagsFromSymbol(propertySymbol) & (ModifierFlags.Private | ModifierFlags.Protected) && context.tracker.reportPrivateInBaseOfClassExpression) { + context.tracker.reportPrivateInBaseOfClassExpression(unescapeLeadingUnderscores(propertySymbol.escapedName)); + } + } + if (checkTruncationLength(context) && (i + 2 < properties.length - 1)) { + typeElements.push(factory.createPropertySignature(/*modifiers*/ undefined, `... ${properties.length - i} more ...`, /*questionToken*/ undefined, /*type*/ undefined)); + addPropertyToElementList(properties[properties.length - 1], context, typeElements); + break; + } + addPropertyToElementList(propertySymbol, context, typeElements); + } + return typeElements.length ? typeElements : undefined; + } + } + + function createElidedInformationPlaceholder(context: NodeBuilderContext) { + context.approximateLength += 3; + if (!(context.flags & NodeBuilderFlags.NoTruncation)) { + return factory.createTypeReferenceNode(factory.createIdentifier("..."), /*typeArguments*/ undefined); + } + return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + + function shouldUsePlaceholderForProperty(propertySymbol: Symbol, context: NodeBuilderContext) { + // Use placeholders for reverse mapped types we've either already descended into, or which + // are nested reverse mappings within a mapping over a non-anonymous type. The later is a restriction mostly just to + // reduce the blowup in printback size from doing, eg, a deep reverse mapping over `Window`. + // Since anonymous types usually come from expressions, this allows us to preserve the output + // for deep mappings which likely come from expressions, while truncating those parts which + // come from mappings over library functions. + return !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped) + && ( + contains(context.reverseMappedStack, propertySymbol as ReverseMappedSymbol) + || ( + context.reverseMappedStack?.[0] + && !(getObjectFlags(last(context.reverseMappedStack).links.propertyType) & ObjectFlags.Anonymous) + ) + ); + } + + function addPropertyToElementList(propertySymbol: Symbol, context: NodeBuilderContext, typeElements: TypeElement[]) { + const propertyIsReverseMapped = !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped); + const propertyType = shouldUsePlaceholderForProperty(propertySymbol, context) ? + anyType : getNonMissingTypeOfSymbol(propertySymbol); + const saveEnclosingDeclaration = context.enclosingDeclaration; + context.enclosingDeclaration = undefined; + if (context.tracker.canTrackSymbol && isLateBoundName(propertySymbol.escapedName)) { + if (propertySymbol.declarations) { + const decl = first(propertySymbol.declarations); + if (hasLateBindableName(decl)) { + if (isBinaryExpression(decl)) { + const name = getNameOfDeclaration(decl); + if (name && isElementAccessExpression(name) && isPropertyAccessEntityNameExpression(name.argumentExpression)) { + trackComputedName(name.argumentExpression, saveEnclosingDeclaration, context); + } + } + else { + trackComputedName(decl.name.expression, saveEnclosingDeclaration, context); + } + } + } + else { + context.tracker.reportNonSerializableProperty(symbolToString(propertySymbol)); + } + } + context.enclosingDeclaration = propertySymbol.valueDeclaration || propertySymbol.declarations?.[0] || saveEnclosingDeclaration; + const propertyName = getPropertyNameNodeForSymbol(propertySymbol, context); + context.enclosingDeclaration = saveEnclosingDeclaration; + context.approximateLength += symbolName(propertySymbol).length + 1; + + if (propertySymbol.flags & SymbolFlags.Accessor) { + const writeType = getWriteTypeOfSymbol(propertySymbol); + if (propertyType !== writeType && !isErrorType(propertyType) && !isErrorType(writeType)) { + const getterDeclaration = getDeclarationOfKind(propertySymbol, SyntaxKind.GetAccessor)!; + const getterSignature = getSignatureFromDeclaration(getterDeclaration); + typeElements.push( + setCommentRange( + context, + signatureToSignatureDeclarationHelper(getterSignature, SyntaxKind.GetAccessor, context, { name: propertyName }) as GetAccessorDeclaration, + getterDeclaration, + ), + ); + const setterDeclaration = getDeclarationOfKind(propertySymbol, SyntaxKind.SetAccessor)!; + const setterSignature = getSignatureFromDeclaration(setterDeclaration); + typeElements.push( + setCommentRange( + context, + signatureToSignatureDeclarationHelper(setterSignature, SyntaxKind.SetAccessor, context, { name: propertyName }) as SetAccessorDeclaration, + setterDeclaration, + ), + ); + return; + } + } + + const optionalToken = propertySymbol.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined; + if (propertySymbol.flags & (SymbolFlags.Function | SymbolFlags.Method) && !getPropertiesOfObjectType(propertyType).length && !isReadonlySymbol(propertySymbol)) { + const signatures = getSignaturesOfType(filterType(propertyType, t => !(t.flags & TypeFlags.Undefined)), SignatureKind.Call); + for (const signature of signatures) { + const methodDeclaration = signatureToSignatureDeclarationHelper(signature, SyntaxKind.MethodSignature, context, { name: propertyName, questionToken: optionalToken }) as MethodSignature; + typeElements.push(preserveCommentsOn(methodDeclaration)); + } + if (signatures.length || !optionalToken) { + return; + } + } + let propertyTypeNode: TypeNode; + if (shouldUsePlaceholderForProperty(propertySymbol, context)) { + propertyTypeNode = createElidedInformationPlaceholder(context); + } + else { + if (propertyIsReverseMapped) { + context.reverseMappedStack ||= []; + context.reverseMappedStack.push(propertySymbol as ReverseMappedSymbol); + } + propertyTypeNode = propertyType ? serializeTypeForDeclaration(context, /*declaration*/ undefined, propertyType, propertySymbol) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + if (propertyIsReverseMapped) { + context.reverseMappedStack!.pop(); + } + } + + const modifiers = isReadonlySymbol(propertySymbol) ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined; + if (modifiers) { + context.approximateLength += 9; + } + const propertySignature = factory.createPropertySignature( + modifiers, + propertyName, + optionalToken, + propertyTypeNode, + ); + + typeElements.push(preserveCommentsOn(propertySignature)); + + function preserveCommentsOn(node: T) { + const jsdocPropertyTag = propertySymbol.declarations?.find((d): d is JSDocPropertyTag => d.kind === SyntaxKind.JSDocPropertyTag); + if (jsdocPropertyTag) { + const commentText = getTextOfJSDocComment(jsdocPropertyTag.comment); + if (commentText) { + setSyntheticLeadingComments(node, [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }]); + } + } + else if (propertySymbol.valueDeclaration) { + // Copy comments to node for declaration emit + setCommentRange(context, node, propertySymbol.valueDeclaration); + } + return node; + } + } + + function setCommentRange(context: NodeBuilderContext, node: T, range: Node): T { + if (context.enclosingFile && context.enclosingFile === getSourceFileOfNode(range)) { + // Copy comments to node for declaration emit + return setCommentRangeWorker(node, range); + } + return node; + } + + function mapToTypeNodes(types: readonly Type[] | undefined, context: NodeBuilderContext, isBareList?: boolean): TypeNode[] | undefined { + if (some(types)) { + if (checkTruncationLength(context)) { + if (!isBareList) { + return [factory.createTypeReferenceNode("...", /*typeArguments*/ undefined)]; + } + else if (types.length > 2) { + return [ + typeToTypeNodeHelper(types[0], context), + factory.createTypeReferenceNode(`... ${types.length - 2} more ...`, /*typeArguments*/ undefined), + typeToTypeNodeHelper(types[types.length - 1], context), + ]; + } + } + const mayHaveNameCollisions = !(context.flags & NodeBuilderFlags.UseFullyQualifiedType); + /** Map from type reference identifier text to [type, index in `result` where the type node is] */ + const seenNames = mayHaveNameCollisions ? createMultiMap<__String, [Type, number]>() : undefined; + const result: TypeNode[] = []; + let i = 0; + for (const type of types) { + i++; + if (checkTruncationLength(context) && (i + 2 < types.length - 1)) { + result.push(factory.createTypeReferenceNode(`... ${types.length - i} more ...`, /*typeArguments*/ undefined)); + const typeNode = typeToTypeNodeHelper(types[types.length - 1], context); + if (typeNode) { + result.push(typeNode); + } + break; + } + context.approximateLength += 2; // Account for whitespace + separator + const typeNode = typeToTypeNodeHelper(type, context); + if (typeNode) { + result.push(typeNode); + if (seenNames && isIdentifierTypeReference(typeNode)) { + seenNames.add(typeNode.typeName.escapedText, [type, result.length - 1]); + } + } + } + + if (seenNames) { + // To avoid printing types like `[Foo, Foo]` or `Bar & Bar` where + // occurrences of the same name actually come from different + // namespaces, go through the single-identifier type reference nodes + // we just generated, and see if any names were generated more than + // once while referring to different types. If so, regenerate the + // type node for each entry by that name with the + // `UseFullyQualifiedType` flag enabled. + const saveContextFlags = context.flags; + context.flags |= NodeBuilderFlags.UseFullyQualifiedType; + seenNames.forEach(types => { + if (!arrayIsHomogeneous(types, ([a], [b]) => typesAreSameReference(a, b))) { + for (const [type, resultIndex] of types) { + result[resultIndex] = typeToTypeNodeHelper(type, context); + } + } + }); + context.flags = saveContextFlags; + } + + return result; + } + } + + function typesAreSameReference(a: Type, b: Type): boolean { + return a === b + || !!a.symbol && a.symbol === b.symbol + || !!a.aliasSymbol && a.aliasSymbol === b.aliasSymbol; + } + + function indexInfoToIndexSignatureDeclarationHelper(indexInfo: IndexInfo, context: NodeBuilderContext, typeNode: TypeNode | undefined): IndexSignatureDeclaration { + const name = getNameFromIndexInfo(indexInfo) || "x"; + const indexerTypeNode = typeToTypeNodeHelper(indexInfo.keyType, context); + + const indexingParameter = factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + name, + /*questionToken*/ undefined, + indexerTypeNode, + /*initializer*/ undefined, + ); + if (!typeNode) { + typeNode = typeToTypeNodeHelper(indexInfo.type || anyType, context); + } + if (!indexInfo.type && !(context.flags & NodeBuilderFlags.AllowEmptyIndexInfoType)) { + context.encounteredError = true; + } + context.approximateLength += name.length + 4; + return factory.createIndexSignature( + indexInfo.isReadonly ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined, + [indexingParameter], + typeNode, + ); + } + + interface SignatureToSignatureDeclarationOptions { + modifiers?: readonly Modifier[]; + name?: PropertyName; + questionToken?: QuestionToken; + } + + function signatureToSignatureDeclarationHelper(signature: Signature, kind: SignatureDeclaration["kind"], context: NodeBuilderContext, options?: SignatureToSignatureDeclarationOptions): SignatureDeclaration { + let typeParameters: TypeParameterDeclaration[] | undefined; + let typeArguments: TypeNode[] | undefined; + + const expandedParams = getExpandedParameters(signature, /*skipUnionExpanding*/ true)[0]; + const cleanup = enterNewScope(context, signature.declaration, expandedParams, signature.typeParameters, signature.parameters, signature.mapper); + context.approximateLength += 3; // Usually a signature contributes a few more characters than this, but 3 is the minimum + + if (context.flags & NodeBuilderFlags.WriteTypeArgumentsOfSignature && signature.target && signature.mapper && signature.target.typeParameters) { + typeArguments = signature.target.typeParameters.map(parameter => typeToTypeNodeHelper(instantiateType(parameter, signature.mapper), context)); + } + else { + typeParameters = signature.typeParameters && signature.typeParameters.map(parameter => typeParameterToDeclaration(parameter, context)); + } + + const flags = context.flags; + context.flags &= ~NodeBuilderFlags.SuppressAnyReturnType; // SuppressAnyReturnType should only apply to the signature `return` position + // If the expanded parameter list had a variadic in a non-trailing position, don't expand it + const parameters = (some(expandedParams, p => p !== expandedParams[expandedParams.length - 1] && !!(getCheckFlags(p) & CheckFlags.RestParameter)) ? signature.parameters : expandedParams).map(parameter => symbolToParameterDeclaration(parameter, context, kind === SyntaxKind.Constructor)); + const thisParameter = context.flags & NodeBuilderFlags.OmitThisParameter ? undefined : tryGetThisParameterDeclaration(signature, context); + if (thisParameter) { + parameters.unshift(thisParameter); + } + context.flags = flags; + + const returnTypeNode = serializeReturnTypeForSignature(context, signature); + + let modifiers = options?.modifiers; + if ((kind === SyntaxKind.ConstructorType) && signature.flags & SignatureFlags.Abstract) { + const flags = modifiersToFlags(modifiers); + modifiers = factory.createModifiersFromModifierFlags(flags | ModifierFlags.Abstract); + } + + const node = kind === SyntaxKind.CallSignature ? factory.createCallSignature(typeParameters, parameters, returnTypeNode) : + kind === SyntaxKind.ConstructSignature ? factory.createConstructSignature(typeParameters, parameters, returnTypeNode) : + kind === SyntaxKind.MethodSignature ? factory.createMethodSignature(modifiers, options?.name ?? factory.createIdentifier(""), options?.questionToken, typeParameters, parameters, returnTypeNode) : + kind === SyntaxKind.MethodDeclaration ? factory.createMethodDeclaration(modifiers, /*asteriskToken*/ undefined, options?.name ?? factory.createIdentifier(""), /*questionToken*/ undefined, typeParameters, parameters, returnTypeNode, /*body*/ undefined) : + kind === SyntaxKind.Constructor ? factory.createConstructorDeclaration(modifiers, parameters, /*body*/ undefined) : + kind === SyntaxKind.GetAccessor ? factory.createGetAccessorDeclaration(modifiers, options?.name ?? factory.createIdentifier(""), parameters, returnTypeNode, /*body*/ undefined) : + kind === SyntaxKind.SetAccessor ? factory.createSetAccessorDeclaration(modifiers, options?.name ?? factory.createIdentifier(""), parameters, /*body*/ undefined) : + kind === SyntaxKind.IndexSignature ? factory.createIndexSignature(modifiers, parameters, returnTypeNode) : + kind === SyntaxKind.JSDocFunctionType ? factory.createJSDocFunctionType(parameters, returnTypeNode) : + kind === SyntaxKind.FunctionType ? factory.createFunctionTypeNode(typeParameters, parameters, returnTypeNode ?? factory.createTypeReferenceNode(factory.createIdentifier(""))) : + kind === SyntaxKind.ConstructorType ? factory.createConstructorTypeNode(modifiers, typeParameters, parameters, returnTypeNode ?? factory.createTypeReferenceNode(factory.createIdentifier(""))) : + kind === SyntaxKind.FunctionDeclaration ? factory.createFunctionDeclaration(modifiers, /*asteriskToken*/ undefined, options?.name ? cast(options.name, isIdentifier) : factory.createIdentifier(""), typeParameters, parameters, returnTypeNode, /*body*/ undefined) : + kind === SyntaxKind.FunctionExpression ? factory.createFunctionExpression(modifiers, /*asteriskToken*/ undefined, options?.name ? cast(options.name, isIdentifier) : factory.createIdentifier(""), typeParameters, parameters, returnTypeNode, factory.createBlock([])) : + kind === SyntaxKind.ArrowFunction ? factory.createArrowFunction(modifiers, typeParameters, parameters, returnTypeNode, /*equalsGreaterThanToken*/ undefined, factory.createBlock([])) : + Debug.assertNever(kind); + + if (typeArguments) { + node.typeArguments = factory.createNodeArray(typeArguments); + } + if (signature.declaration?.kind === SyntaxKind.JSDocSignature && signature.declaration.parent.kind === SyntaxKind.JSDocOverloadTag) { + const comment = getTextOfNode(signature.declaration.parent.parent, /*includeTrivia*/ true).slice(2, -2).split(/\r\n|\n|\r/).map(line => line.replace(/^\s+/, " ")).join("\n"); + addSyntheticLeadingComment(node, SyntaxKind.MultiLineCommentTrivia, comment, /*hasTrailingNewLine*/ true); + } + + cleanup?.(); + return node; + } + + type IntroducesNewScopeNode = SignatureDeclaration | JSDocSignature | MappedTypeNode; + + function isNewScopeNode(node: Node): node is IntroducesNewScopeNode { + return isFunctionLike(node) + || isJSDocSignature(node) + || isMappedTypeNode(node); + } + + function getTypeParametersInScope(node: IntroducesNewScopeNode | ConditionalTypeNode) { + return isFunctionLike(node) || isJSDocSignature(node) ? getSignatureFromDeclaration(node).typeParameters : + isConditionalTypeNode(node) ? getInferTypeParameters(node) : + [getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node.typeParameter))]; + } + + function getParametersInScope(node: IntroducesNewScopeNode | ConditionalTypeNode) { + return isFunctionLike(node) || isJSDocSignature(node) ? getSignatureFromDeclaration(node).parameters : undefined; + } + + function enterNewScope( + context: NodeBuilderContext, + declaration: IntroducesNewScopeNode | ConditionalTypeNode | undefined, + expandedParams: readonly Symbol[] | undefined, + typeParameters: readonly TypeParameter[] | undefined, + originalParameters?: readonly Symbol[] | undefined, + mapper?: TypeMapper, + ) { + const cleanupContext = cloneNodeBuilderContext(context); + // For regular function/method declarations, the enclosing declaration will already be signature.declaration, + // so this is a no-op, but for arrow functions and function expressions, the enclosing declaration will be + // the declaration that the arrow function / function expression is assigned to. + // + // If the parameters or return type include "typeof globalThis.paramName", using the wrong scope will lead + // us to believe that we can emit "typeof paramName" instead, even though that would refer to the parameter, + // not the global. Make sure we are in the right scope by changing the enclosingDeclaration to the function. + // + // We can't use the declaration directly; it may be in another file and so we may lose access to symbols + // accessible to the current enclosing declaration, or gain access to symbols not accessible to the current + // enclosing declaration. To keep this chain accurate, insert a fake scope into the chain which makes the + // function's parameters visible. + let cleanupParams: (() => void) | undefined; + let cleanupTypeParams: (() => void) | undefined; + const oldEnclosingDecl = context.enclosingDeclaration; + const oldMapper = context.mapper; + if (mapper) { + context.mapper = mapper; + } + if (context.enclosingDeclaration && declaration) { + // As a performance optimization, reuse the same fake scope within this chain. + // This is especially needed when we are working on an excessively deep type; + // if we don't do this, then we spend all of our time adding more and more + // scopes that need to be searched in isSymbolAccessible later. Since all we + // really want to do is to mark certain names as unavailable, we can just keep + // all of the names we're introducing in one large table and push/pop from it as + // needed; isSymbolAccessible will walk upward and find the closest "fake" scope, + // which will conveniently report on any and all faked scopes in the chain. + // + // It'd likely be better to store this somewhere else for isSymbolAccessible, but + // since that API _only_ uses the enclosing declaration (and its parents), this is + // seems like the best way to inject names into that search process. + // + // Note that we only check the most immediate enclosingDeclaration; the only place we + // could potentially add another fake scope into the chain is right here, so we don't + // traverse all ancestors. + cleanupParams = !some(expandedParams) ? undefined : pushFakeScope( + "params", + add => { + if (!expandedParams) return; + for (let pIndex = 0; pIndex < expandedParams.length; pIndex++) { + const param = expandedParams[pIndex]; + const originalParam = originalParameters?.[pIndex]; + if (originalParameters && originalParam !== param) { + // Can't reference parameters that come from an expansion + add(param.escapedName, unknownSymbol); + // Can't reference the original expanded parameter either + if (originalParam) { + add(originalParam.escapedName, unknownSymbol); + } + } + else if ( + !forEach(param.declarations, d => { + if (isParameter(d) && isBindingPattern(d.name)) { + bindPattern(d.name); + return true; + } + return undefined; + function bindPattern(p: BindingPattern): void { + forEach(p.elements, e => { + switch (e.kind) { + case SyntaxKind.OmittedExpression: + return; + case SyntaxKind.BindingElement: + return bindElement(e); + default: + return Debug.assertNever(e); + } + }); + } + function bindElement(e: BindingElement): void { + if (isBindingPattern(e.name)) { + return bindPattern(e.name); + } + const symbol = getSymbolOfDeclaration(e); + add(symbol.escapedName, symbol); + } + }) + ) { + add(param.escapedName, param); + } + } + }, + ); + + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && some(typeParameters)) { + cleanupTypeParams = pushFakeScope( + "typeParams", + add => { + for (const typeParam of typeParameters ?? emptyArray) { + const typeParamName = typeParameterToName(typeParam, context).escapedText; + add(typeParamName, typeParam.symbol); + } + }, + ); + } + + function pushFakeScope(kind: "params" | "typeParams", addAll: (addSymbol: (name: __String, symbol: Symbol) => void) => void) { + // We only ever need to look two declarations upward. + Debug.assert(context.enclosingDeclaration); + let existingFakeScope: Node | undefined; + if (getNodeLinks(context.enclosingDeclaration).fakeScopeForSignatureDeclaration === kind) { + existingFakeScope = context.enclosingDeclaration; + } + else if (context.enclosingDeclaration.parent && getNodeLinks(context.enclosingDeclaration.parent).fakeScopeForSignatureDeclaration === kind) { + existingFakeScope = context.enclosingDeclaration.parent; + } + Debug.assertOptionalNode(existingFakeScope, isBlock); + + const locals = existingFakeScope?.locals ?? createSymbolTable(); + let newLocals: __String[] | undefined; + let oldLocals: { name: __String; oldSymbol: Symbol; }[] | undefined; + addAll((name, symbol) => { + // Add cleanup information only if we don't own the fake scope + if (existingFakeScope) { + const oldSymbol = locals.get(name); + if (!oldSymbol) { + newLocals = append(newLocals, name); + } + else { + oldLocals = append(oldLocals, { name, oldSymbol }); + } + } + locals.set(name, symbol); + }); + + if (!existingFakeScope) { + // Use a Block for this; the type of the node doesn't matter so long as it + // has locals, and this is cheaper/easier than using a function-ish Node. + const fakeScope = factory.createBlock(emptyArray); + getNodeLinks(fakeScope).fakeScopeForSignatureDeclaration = kind; + fakeScope.locals = locals; + + setParent(fakeScope, context.enclosingDeclaration); + context.enclosingDeclaration = fakeScope; + } + else { + // We did not create the current scope, so we have to clean it up + return function undo() { + forEach(newLocals, s => locals.delete(s)); + forEach(oldLocals, s => locals.set(s.name, s.oldSymbol)); + }; + } + } + } + + return () => { + cleanupParams?.(); + cleanupTypeParams?.(); + cleanupContext(); + context.enclosingDeclaration = oldEnclosingDecl; + context.mapper = oldMapper; + }; + } + + function tryGetThisParameterDeclaration(signature: Signature, context: NodeBuilderContext) { + if (signature.thisParameter) { + return symbolToParameterDeclaration(signature.thisParameter, context); + } + if (signature.declaration && isInJSFile(signature.declaration)) { + const thisTag = getJSDocThisTag(signature.declaration); + if (thisTag && thisTag.typeExpression) { + return factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + "this", + /*questionToken*/ undefined, + typeToTypeNodeHelper(getTypeFromTypeNode(context, thisTag.typeExpression), context), + ); + } + } + } + + function typeParameterToDeclarationWithConstraint(type: TypeParameter, context: NodeBuilderContext, constraintNode: TypeNode | undefined): TypeParameterDeclaration { + const savedContextFlags = context.flags; + context.flags &= ~NodeBuilderFlags.WriteTypeParametersInQualifiedName; // Avoids potential infinite loop when building for a claimspace with a generic + const modifiers = factory.createModifiersFromModifierFlags(getTypeParameterModifiers(type)); + const name = typeParameterToName(type, context); + const defaultParameter = getDefaultFromTypeParameter(type); + const defaultParameterNode = defaultParameter && typeToTypeNodeHelper(defaultParameter, context); + context.flags = savedContextFlags; + return factory.createTypeParameterDeclaration(modifiers, name, constraintNode, defaultParameterNode); + } + + function typeToTypeNodeHelperWithPossibleReusableTypeNode(type: Type, typeNode: TypeNode | undefined, context: NodeBuilderContext) { + return typeNode && tryReuseExistingNonParameterTypeNode(context, typeNode, type) || typeToTypeNodeHelper(type, context); + } + + function typeParameterToDeclaration(type: TypeParameter, context: NodeBuilderContext, constraint = getConstraintOfTypeParameter(type)): TypeParameterDeclaration { + const constraintNode = constraint && typeToTypeNodeHelperWithPossibleReusableTypeNode(constraint, getConstraintDeclaration(type), context); + return typeParameterToDeclarationWithConstraint(type, context, constraintNode); + } + + function typePredicateToTypePredicateNodeHelper(typePredicate: TypePredicate, context: NodeBuilderContext): TypePredicateNode { + const assertsModifier = typePredicate.kind === TypePredicateKind.AssertsThis || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? + factory.createToken(SyntaxKind.AssertsKeyword) : + undefined; + const parameterName = typePredicate.kind === TypePredicateKind.Identifier || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? + setEmitFlags(factory.createIdentifier(typePredicate.parameterName), EmitFlags.NoAsciiEscaping) : + factory.createThisTypeNode(); + const typeNode = typePredicate.type && typeToTypeNodeHelper(typePredicate.type, context); + return factory.createTypePredicateNode(assertsModifier, parameterName, typeNode); + } + + function getEffectiveParameterDeclaration(parameterSymbol: Symbol): ParameterDeclaration | JSDocParameterTag | undefined { + const parameterDeclaration: ParameterDeclaration | JSDocParameterTag | undefined = getDeclarationOfKind(parameterSymbol, SyntaxKind.Parameter); + if (parameterDeclaration) { + return parameterDeclaration; + } + if (!isTransientSymbol(parameterSymbol)) { + return getDeclarationOfKind(parameterSymbol, SyntaxKind.JSDocParameterTag); + } + } + + function symbolToParameterDeclaration(parameterSymbol: Symbol, context: NodeBuilderContext, preserveModifierFlags?: boolean): ParameterDeclaration { + const parameterDeclaration = getEffectiveParameterDeclaration(parameterSymbol); + + const parameterType = getTypeOfSymbol(parameterSymbol); + const parameterTypeNode = serializeTypeForDeclaration(context, parameterDeclaration, parameterType, parameterSymbol); + + const modifiers = !(context.flags & NodeBuilderFlags.OmitParameterModifiers) && preserveModifierFlags && parameterDeclaration && canHaveModifiers(parameterDeclaration) ? map(getModifiers(parameterDeclaration), factory.cloneNode) : undefined; + const isRest = parameterDeclaration && isRestParameter(parameterDeclaration) || getCheckFlags(parameterSymbol) & CheckFlags.RestParameter; + const dotDotDotToken = isRest ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined; + const name = parameterToParameterDeclarationName(parameterSymbol, parameterDeclaration, context); + const isOptional = parameterDeclaration && isOptionalParameter(parameterDeclaration) || getCheckFlags(parameterSymbol) & CheckFlags.OptionalParameter; + const questionToken = isOptional ? factory.createToken(SyntaxKind.QuestionToken) : undefined; + const parameterNode = factory.createParameterDeclaration( + modifiers, + dotDotDotToken, + name, + questionToken, + parameterTypeNode, + /*initializer*/ undefined, + ); + context.approximateLength += symbolName(parameterSymbol).length + 3; + return parameterNode; + } + + function parameterToParameterDeclarationName(parameterSymbol: Symbol, parameterDeclaration: ParameterDeclaration | JSDocParameterTag | undefined, context: NodeBuilderContext) { + return parameterDeclaration ? parameterDeclaration.name ? + parameterDeclaration.name.kind === SyntaxKind.Identifier ? setEmitFlags(factory.cloneNode(parameterDeclaration.name), EmitFlags.NoAsciiEscaping) : + parameterDeclaration.name.kind === SyntaxKind.QualifiedName ? setEmitFlags(factory.cloneNode(parameterDeclaration.name.right), EmitFlags.NoAsciiEscaping) : + cloneBindingName(parameterDeclaration.name) : + symbolName(parameterSymbol) : + symbolName(parameterSymbol); + + function cloneBindingName(node: BindingName): BindingName { + return elideInitializerAndSetEmitFlags(node) as BindingName; + function elideInitializerAndSetEmitFlags(node: Node): Node { + if (context.tracker.canTrackSymbol && isComputedPropertyName(node) && isLateBindableName(node)) { + trackComputedName(node.expression, context.enclosingDeclaration, context); + } + let visited = visitEachChildWorker(node, elideInitializerAndSetEmitFlags, /*context*/ undefined, /*nodesVisitor*/ undefined, elideInitializerAndSetEmitFlags); + if (isBindingElement(visited)) { + visited = factory.updateBindingElement( + visited, + visited.dotDotDotToken, + visited.propertyName, + visited.name, + /*initializer*/ undefined, + ); + } + if (!nodeIsSynthesized(visited)) { + visited = factory.cloneNode(visited); + } + return setEmitFlags(visited, EmitFlags.SingleLine | EmitFlags.NoAsciiEscaping); + } + } + } + + function trackComputedName(accessExpression: EntityNameOrEntityNameExpression, enclosingDeclaration: Node | undefined, context: NodeBuilderContext) { + if (!context.tracker.canTrackSymbol) return; + // get symbol of the first identifier of the entityName + const firstIdentifier = getFirstIdentifier(accessExpression); + const name = resolveName(firstIdentifier, firstIdentifier.escapedText, SymbolFlags.Value | SymbolFlags.ExportValue, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (name) { + context.tracker.trackSymbol(name, enclosingDeclaration, SymbolFlags.Value); + } + } + + function lookupSymbolChain(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, yieldModuleSymbol?: boolean) { + context.tracker.trackSymbol(symbol, context.enclosingDeclaration, meaning); + return lookupSymbolChainWorker(symbol, context, meaning, yieldModuleSymbol); + } + + function lookupSymbolChainWorker(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, yieldModuleSymbol?: boolean) { + // Try to get qualified name if the symbol is not a type parameter and there is an enclosing declaration. + let chain: Symbol[]; + const isTypeParameter = symbol.flags & SymbolFlags.TypeParameter; + if (!isTypeParameter && (context.enclosingDeclaration || context.flags & NodeBuilderFlags.UseFullyQualifiedType) && !(context.flags & NodeBuilderFlags.DoNotIncludeSymbolChain)) { + chain = Debug.checkDefined(getSymbolChain(symbol, meaning, /*endOfChain*/ true)); + Debug.assert(chain && chain.length > 0); + } + else { + chain = [symbol]; + } + return chain; + + /** @param endOfChain Set to false for recursive calls; non-recursive calls should always output something. */ + function getSymbolChain(symbol: Symbol, meaning: SymbolFlags, endOfChain: boolean): Symbol[] | undefined { + let accessibleSymbolChain = getAccessibleSymbolChain(symbol, context.enclosingDeclaration, meaning, !!(context.flags & NodeBuilderFlags.UseOnlyExternalAliasing)); + let parentSpecifiers: (string | undefined)[]; + if ( + !accessibleSymbolChain || + needsQualification(accessibleSymbolChain[0], context.enclosingDeclaration, accessibleSymbolChain.length === 1 ? meaning : getQualifiedLeftMeaning(meaning)) + ) { + // Go up and add our parent. + const parents = getContainersOfSymbol(accessibleSymbolChain ? accessibleSymbolChain[0] : symbol, context.enclosingDeclaration, meaning); + if (length(parents)) { + parentSpecifiers = parents!.map(symbol => + some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol) + ? getSpecifierForModuleSymbol(symbol, context) + : undefined + ); + const indices = parents!.map((_, i) => i); + indices.sort(sortByBestName); + const sortedParents = indices.map(i => parents![i]); + for (const parent of sortedParents) { + const parentChain = getSymbolChain(parent, getQualifiedLeftMeaning(meaning), /*endOfChain*/ false); + if (parentChain) { + if ( + parent.exports && parent.exports.get(InternalSymbolName.ExportEquals) && + getSymbolIfSameReference(parent.exports.get(InternalSymbolName.ExportEquals)!, symbol) + ) { + // parentChain root _is_ symbol - symbol is a module export=, so it kinda looks like it's own parent + // No need to lookup an alias for the symbol in itself + accessibleSymbolChain = parentChain; + break; + } + accessibleSymbolChain = parentChain.concat(accessibleSymbolChain || [getAliasForSymbolInContainer(parent, symbol) || symbol]); + break; + } + } + } + } + + if (accessibleSymbolChain) { + return accessibleSymbolChain; + } + if ( + // If this is the last part of outputting the symbol, always output. The cases apply only to parent symbols. + endOfChain || + // If a parent symbol is an anonymous type, don't write it. + !(symbol.flags & (SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral)) + ) { + // If a parent symbol is an external module, don't write it. (We prefer just `x` vs `"foo/bar".x`.) + if (!endOfChain && !yieldModuleSymbol && !!forEach(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + return; + } + return [symbol]; + } + + function sortByBestName(a: number, b: number) { + const specifierA = parentSpecifiers[a]; + const specifierB = parentSpecifiers[b]; + if (specifierA && specifierB) { + const isBRelative = pathIsRelative(specifierB); + if (pathIsRelative(specifierA) === isBRelative) { + // Both relative or both non-relative, sort by number of parts + return moduleSpecifiers.countPathComponents(specifierA) - moduleSpecifiers.countPathComponents(specifierB); + } + if (isBRelative) { + // A is non-relative, B is relative: prefer A + return -1; + } + // A is relative, B is non-relative: prefer B + return 1; + } + return 0; + } + } + } + + function typeParametersToTypeParameterDeclarations(symbol: Symbol, context: NodeBuilderContext) { + let typeParameterNodes: NodeArray | undefined; + const targetSymbol = getTargetSymbol(symbol); + if (targetSymbol.flags & (SymbolFlags.Class | SymbolFlags.Interface | SymbolFlags.TypeAlias)) { + typeParameterNodes = factory.createNodeArray(map(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol), tp => typeParameterToDeclaration(tp, context))); + } + return typeParameterNodes; + } + + function lookupTypeParameterNodes(chain: Symbol[], index: number, context: NodeBuilderContext) { + Debug.assert(chain && 0 <= index && index < chain.length); + const symbol = chain[index]; + const symbolId = getSymbolId(symbol); + if (context.typeParameterSymbolList?.has(symbolId)) { + return undefined; + } + if (context.mustCreateTypeParameterSymbolList) { + context.mustCreateTypeParameterSymbolList = false; + context.typeParameterSymbolList = new Set(context.typeParameterSymbolList); + } + context.typeParameterSymbolList!.add(symbolId); + let typeParameterNodes: readonly TypeNode[] | readonly TypeParameterDeclaration[] | undefined; + if (context.flags & NodeBuilderFlags.WriteTypeParametersInQualifiedName && index < (chain.length - 1)) { + const parentSymbol = symbol; + const nextSymbol = chain[index + 1]; + if (getCheckFlags(nextSymbol) & CheckFlags.Instantiated) { + const params = getTypeParametersOfClassOrInterface( + parentSymbol.flags & SymbolFlags.Alias ? resolveAlias(parentSymbol) : parentSymbol, + ); + // NOTE: cast to TransientSymbol should be safe because only TransientSymbol can have CheckFlags.Instantiated + typeParameterNodes = mapToTypeNodes(map(params, t => getMappedType(t, (nextSymbol as TransientSymbol).links.mapper!)), context); + } + else { + typeParameterNodes = typeParametersToTypeParameterDeclarations(symbol, context); + } + } + return typeParameterNodes; + } + + /** + * Given A[B][C][D], finds A[B] + */ + function getTopmostIndexedAccessType(top: IndexedAccessTypeNode): IndexedAccessTypeNode { + if (isIndexedAccessTypeNode(top.objectType)) { + return getTopmostIndexedAccessType(top.objectType); + } + return top; + } + + function getSpecifierForModuleSymbol(symbol: Symbol, context: NodeBuilderContext, overrideImportMode?: ResolutionMode) { + let file = getDeclarationOfKind(symbol, SyntaxKind.SourceFile); + if (!file) { + const equivalentFileSymbol = firstDefined(symbol.declarations, d => getFileSymbolIfFileSymbolExportEqualsContainer(d, symbol)); + if (equivalentFileSymbol) { + file = getDeclarationOfKind(equivalentFileSymbol, SyntaxKind.SourceFile); + } + } + if (file && file.moduleName !== undefined) { + // Use the amd name if it is available + return file.moduleName; + } + if (!file) { + if (ambientModuleSymbolRegex.test(symbol.escapedName as string)) { + return (symbol.escapedName as string).substring(1, (symbol.escapedName as string).length - 1); + } + } + if (!context.enclosingFile || !context.tracker.moduleResolverHost) { + // If there's no context declaration, we can't lookup a non-ambient specifier, so we just use the symbol name + if (ambientModuleSymbolRegex.test(symbol.escapedName as string)) { + return (symbol.escapedName as string).substring(1, (symbol.escapedName as string).length - 1); + } + return getSourceFileOfNode(getNonAugmentationDeclaration(symbol)!).fileName; // A resolver may not be provided for baselines and errors - in those cases we use the fileName in full + } + const contextFile = context.enclosingFile; + const resolutionMode = overrideImportMode || contextFile?.impliedNodeFormat; + const cacheKey = createModeAwareCacheKey(contextFile.path, resolutionMode); + const links = getSymbolLinks(symbol); + let specifier = links.specifierCache && links.specifierCache.get(cacheKey); + if (!specifier) { + const isBundle = !!compilerOptions.outFile; + // For declaration bundles, we need to generate absolute paths relative to the common source dir for imports, + // just like how the declaration emitter does for the ambient module declarations - we can easily accomplish this + // using the `baseUrl` compiler option (which we would otherwise never use in declaration emit) and a non-relative + // specifier preference + const { moduleResolverHost } = context.tracker; + const specifierCompilerOptions = isBundle ? { ...compilerOptions, baseUrl: moduleResolverHost.getCommonSourceDirectory() } : compilerOptions; + specifier = first(moduleSpecifiers.getModuleSpecifiers( + symbol, + checker, + specifierCompilerOptions, + contextFile, + moduleResolverHost, + { + importModuleSpecifierPreference: isBundle ? "non-relative" : "project-relative", + importModuleSpecifierEnding: isBundle ? "minimal" + : resolutionMode === ModuleKind.ESNext ? "js" + : undefined, + }, + { overrideImportMode }, + )); + links.specifierCache ??= new Map(); + links.specifierCache.set(cacheKey, specifier); + } + return specifier; + } + + function symbolToEntityNameNode(symbol: Symbol): EntityName { + const identifier = factory.createIdentifier(unescapeLeadingUnderscores(symbol.escapedName)); + return symbol.parent ? factory.createQualifiedName(symbolToEntityNameNode(symbol.parent), identifier) : identifier; + } + + function symbolToTypeNode(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, overrideTypeArguments?: readonly TypeNode[]): TypeNode { + const chain = lookupSymbolChain(symbol, context, meaning, !(context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope)); // If we're using aliases outside the current scope, dont bother with the module + + const isTypeOf = meaning === SymbolFlags.Value; + if (some(chain[0].declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + // module is root, must use `ImportTypeNode` + const nonRootParts = chain.length > 1 ? createAccessFromSymbolChain(chain, chain.length - 1, 1) : undefined; + const typeParameterNodes = overrideTypeArguments || lookupTypeParameterNodes(chain, 0, context); + const contextFile = getSourceFileOfNode(getOriginalNode(context.enclosingDeclaration)); + const targetFile = getSourceFileOfModule(chain[0]); + let specifier: string | undefined; + let attributes: ImportAttributes | undefined; + if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) { + // An `import` type directed at an esm format file is only going to resolve in esm mode - set the esm mode assertion + if (targetFile?.impliedNodeFormat === ModuleKind.ESNext && targetFile.impliedNodeFormat !== contextFile?.impliedNodeFormat) { + specifier = getSpecifierForModuleSymbol(chain[0], context, ModuleKind.ESNext); + attributes = factory.createImportAttributes( + factory.createNodeArray([ + factory.createImportAttribute( + factory.createStringLiteral("resolution-mode"), + factory.createStringLiteral("import"), + ), + ]), + ); + } + } + if (!specifier) { + specifier = getSpecifierForModuleSymbol(chain[0], context); + } + if (!(context.flags & NodeBuilderFlags.AllowNodeModulesRelativePaths) && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Classic && specifier.includes("/node_modules/")) { + const oldSpecifier = specifier; + if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) { + // We might be able to write a portable import type using a mode override; try specifier generation again, but with a different mode set + const swappedMode = contextFile?.impliedNodeFormat === ModuleKind.ESNext ? ModuleKind.CommonJS : ModuleKind.ESNext; + specifier = getSpecifierForModuleSymbol(chain[0], context, swappedMode); + + if (specifier.includes("/node_modules/")) { + // Still unreachable :( + specifier = oldSpecifier; + } + else { + attributes = factory.createImportAttributes( + factory.createNodeArray([ + factory.createImportAttribute( + factory.createStringLiteral("resolution-mode"), + factory.createStringLiteral(swappedMode === ModuleKind.ESNext ? "import" : "require"), + ), + ]), + ); + } + } + + if (!attributes) { + // If ultimately we can only name the symbol with a reference that dives into a `node_modules` folder, we should error + // since declaration files with these kinds of references are liable to fail when published :( + context.encounteredError = true; + if (context.tracker.reportLikelyUnsafeImportRequiredError) { + context.tracker.reportLikelyUnsafeImportRequiredError(oldSpecifier); + } + } + } + const lit = factory.createLiteralTypeNode(factory.createStringLiteral(specifier)); + context.approximateLength += specifier.length + 10; // specifier + import("") + if (!nonRootParts || isEntityName(nonRootParts)) { + if (nonRootParts) { + const lastId = isIdentifier(nonRootParts) ? nonRootParts : nonRootParts.right; + setIdentifierTypeArguments(lastId, /*typeArguments*/ undefined); + } + return factory.createImportTypeNode(lit, attributes, nonRootParts as EntityName, typeParameterNodes as readonly TypeNode[], isTypeOf); + } + else { + const splitNode = getTopmostIndexedAccessType(nonRootParts); + const qualifier = (splitNode.objectType as TypeReferenceNode).typeName; + return factory.createIndexedAccessTypeNode(factory.createImportTypeNode(lit, attributes, qualifier, typeParameterNodes as readonly TypeNode[], isTypeOf), splitNode.indexType); + } + } + + const entityName = createAccessFromSymbolChain(chain, chain.length - 1, 0); + if (isIndexedAccessTypeNode(entityName)) { + return entityName; // Indexed accesses can never be `typeof` + } + if (isTypeOf) { + return factory.createTypeQueryNode(entityName); + } + else { + const lastId = isIdentifier(entityName) ? entityName : entityName.right; + const lastTypeArgs = getIdentifierTypeArguments(lastId); + setIdentifierTypeArguments(lastId, /*typeArguments*/ undefined); + return factory.createTypeReferenceNode(entityName, lastTypeArgs as NodeArray); + } + + function createAccessFromSymbolChain(chain: Symbol[], index: number, stopper: number): EntityName | IndexedAccessTypeNode { + const typeParameterNodes = index === (chain.length - 1) ? overrideTypeArguments : lookupTypeParameterNodes(chain, index, context); + const symbol = chain[index]; + const parent = chain[index - 1]; + + let symbolName: string | undefined; + if (index === 0) { + context.flags |= NodeBuilderFlags.InInitialEntityName; + symbolName = getNameOfSymbolAsWritten(symbol, context); + context.approximateLength += (symbolName ? symbolName.length : 0) + 1; + context.flags ^= NodeBuilderFlags.InInitialEntityName; + } + else { + if (parent && getExportsOfSymbol(parent)) { + const exports = getExportsOfSymbol(parent); + forEachEntry(exports, (ex, name) => { + if (getSymbolIfSameReference(ex, symbol) && !isLateBoundName(name) && name !== InternalSymbolName.ExportEquals) { + symbolName = unescapeLeadingUnderscores(name); + return true; + } + }); + } + } + + if (symbolName === undefined) { + const name = firstDefined(symbol.declarations, getNameOfDeclaration); + if (name && isComputedPropertyName(name) && isEntityName(name.expression)) { + const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); + if (isEntityName(LHS)) { + return factory.createIndexedAccessTypeNode(factory.createParenthesizedType(factory.createTypeQueryNode(LHS)), factory.createTypeQueryNode(name.expression)); + } + return LHS; + } + symbolName = getNameOfSymbolAsWritten(symbol, context); + } + context.approximateLength += symbolName.length + 1; + + if ( + !(context.flags & NodeBuilderFlags.ForbidIndexedAccessSymbolReferences) && parent && + getMembersOfSymbol(parent) && getMembersOfSymbol(parent).get(symbol.escapedName) && + getSymbolIfSameReference(getMembersOfSymbol(parent).get(symbol.escapedName)!, symbol) + ) { + // Should use an indexed access + const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); + if (isIndexedAccessTypeNode(LHS)) { + return factory.createIndexedAccessTypeNode(LHS, factory.createLiteralTypeNode(factory.createStringLiteral(symbolName))); + } + else { + return factory.createIndexedAccessTypeNode(factory.createTypeReferenceNode(LHS, typeParameterNodes as readonly TypeNode[]), factory.createLiteralTypeNode(factory.createStringLiteral(symbolName))); + } + } + + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + + if (index > stopper) { + const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); + if (!isEntityName(LHS)) { + return Debug.fail("Impossible construct - an export of an indexed access cannot be reachable"); + } + return factory.createQualifiedName(LHS, identifier); + } + return identifier; + } + } + + function typeParameterShadowsOtherTypeParameterInScope(escapedName: __String, context: NodeBuilderContext, type: TypeParameter) { + const result = resolveName(context.enclosingDeclaration, escapedName, SymbolFlags.Type, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (result && result.flags & SymbolFlags.TypeParameter) { + return result !== type.symbol; + } + return false; + } + + function typeParameterToName(type: TypeParameter, context: NodeBuilderContext) { + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && context.typeParameterNames) { + const cached = context.typeParameterNames.get(getTypeId(type)); + if (cached) { + return cached; + } + } + let result = symbolToName(type.symbol, context, SymbolFlags.Type, /*expectsIdentifier*/ true); + if (!(result.kind & SyntaxKind.Identifier)) { + return factory.createIdentifier("(Missing type parameter)"); + } + const decl = type.symbol?.declarations?.[0]; + if (decl && isTypeParameterDeclaration(decl)) { + result = setTextRange(context, result, decl.name); + } + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { + const rawtext = result.escapedText as string; + let i = context.typeParameterNamesByTextNextNameCount?.get(rawtext) || 0; + let text = rawtext; + while (context.typeParameterNamesByText?.has(text) || typeParameterShadowsOtherTypeParameterInScope(text as __String, context, type)) { + i++; + text = `${rawtext}_${i}`; + } + if (text !== rawtext) { + const typeArguments = getIdentifierTypeArguments(result); + result = factory.createIdentifier(text); + setIdentifierTypeArguments(result, typeArguments); + } + if (context.mustCreateTypeParametersNamesLookups) { + context.mustCreateTypeParametersNamesLookups = false; + context.typeParameterNames = new Map(context.typeParameterNames); + context.typeParameterNamesByTextNextNameCount = new Map(context.typeParameterNamesByTextNextNameCount); + context.typeParameterNamesByText = new Set(context.typeParameterNamesByText); + } + // avoiding iterations of the above loop turns out to be worth it when `i` starts to get large, so we cache the max + // `i` we've used thus far, to save work later + context.typeParameterNamesByTextNextNameCount!.set(rawtext, i); + context.typeParameterNames!.set(getTypeId(type), result); + context.typeParameterNamesByText!.add(text); + } + return result; + } + + function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: true): Identifier; + function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: false): EntityName; + function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: boolean): EntityName { + const chain = lookupSymbolChain(symbol, context, meaning); + + if ( + expectsIdentifier && chain.length !== 1 + && !context.encounteredError + && !(context.flags & NodeBuilderFlags.AllowQualifiedNameInPlaceOfIdentifier) + ) { + context.encounteredError = true; + } + return createEntityNameFromSymbolChain(chain, chain.length - 1); + + function createEntityNameFromSymbolChain(chain: Symbol[], index: number): EntityName { + const typeParameterNodes = lookupTypeParameterNodes(chain, index, context); + const symbol = chain[index]; + + if (index === 0) { + context.flags |= NodeBuilderFlags.InInitialEntityName; + } + const symbolName = getNameOfSymbolAsWritten(symbol, context); + if (index === 0) { + context.flags ^= NodeBuilderFlags.InInitialEntityName; + } + + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + + return index > 0 ? factory.createQualifiedName(createEntityNameFromSymbolChain(chain, index - 1), identifier) : identifier; + } + } + + function symbolToExpression(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags) { + const chain = lookupSymbolChain(symbol, context, meaning); + + return createExpressionFromSymbolChain(chain, chain.length - 1); + + function createExpressionFromSymbolChain(chain: Symbol[], index: number): Expression { + const typeParameterNodes = lookupTypeParameterNodes(chain, index, context); + const symbol = chain[index]; + + if (index === 0) { + context.flags |= NodeBuilderFlags.InInitialEntityName; + } + let symbolName = getNameOfSymbolAsWritten(symbol, context); + if (index === 0) { + context.flags ^= NodeBuilderFlags.InInitialEntityName; + } + let firstChar = symbolName.charCodeAt(0); + + if (isSingleOrDoubleQuote(firstChar) && some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + return factory.createStringLiteral(getSpecifierForModuleSymbol(symbol, context)); + } + if (index === 0 || canUsePropertyAccess(symbolName, languageVersion)) { + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + + return index > 0 ? factory.createPropertyAccessExpression(createExpressionFromSymbolChain(chain, index - 1), identifier) : identifier; + } + else { + if (firstChar === CharacterCodes.openBracket) { + symbolName = symbolName.substring(1, symbolName.length - 1); + firstChar = symbolName.charCodeAt(0); + } + let expression: Expression | undefined; + if (isSingleOrDoubleQuote(firstChar) && !(symbol.flags & SymbolFlags.EnumMember)) { + expression = factory.createStringLiteral(stripQuotes(symbolName).replace(/\\./g, s => s.substring(1)), firstChar === CharacterCodes.singleQuote); + } + else if (("" + +symbolName) === symbolName) { + expression = factory.createNumericLiteral(+symbolName); + } + if (!expression) { + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + expression = identifier; + } + return factory.createElementAccessExpression(createExpressionFromSymbolChain(chain, index - 1), expression); + } + } + } + + function isStringNamed(d: Declaration) { + const name = getNameOfDeclaration(d); + if (!name) { + return false; + } + if (isComputedPropertyName(name)) { + const type = checkExpression(name.expression); + return !!(type.flags & TypeFlags.StringLike); + } + if (isElementAccessExpression(name)) { + const type = checkExpression(name.argumentExpression); + return !!(type.flags & TypeFlags.StringLike); + } + return isStringLiteral(name); + } + + function isSingleQuotedStringNamed(d: Declaration) { + const name = getNameOfDeclaration(d); + return !!(name && isStringLiteral(name) && (name.singleQuote || !nodeIsSynthesized(name) && startsWith(getTextOfNode(name, /*includeTrivia*/ false), "'"))); + } + + function getPropertyNameNodeForSymbol(symbol: Symbol, context: NodeBuilderContext) { + const stringNamed = !!length(symbol.declarations) && every(symbol.declarations, isStringNamed); + const singleQuote = !!length(symbol.declarations) && every(symbol.declarations, isSingleQuotedStringNamed); + const isMethod = !!(symbol.flags & SymbolFlags.Method); + const fromNameType = getPropertyNameNodeForSymbolFromNameType(symbol, context, singleQuote, stringNamed, isMethod); + if (fromNameType) { + return fromNameType; + } + const rawName = unescapeLeadingUnderscores(symbol.escapedName); + return createPropertyNameNodeForIdentifierOrLiteral(rawName, getEmitScriptTarget(compilerOptions), singleQuote, stringNamed, isMethod); + } + + // See getNameForSymbolFromNameType for a stringy equivalent + function getPropertyNameNodeForSymbolFromNameType(symbol: Symbol, context: NodeBuilderContext, singleQuote: boolean, stringNamed: boolean, isMethod: boolean) { + const nameType = getSymbolLinks(symbol).nameType; + if (nameType) { + if (nameType.flags & TypeFlags.StringOrNumberLiteral) { + const name = "" + (nameType as StringLiteralType | NumberLiteralType).value; + if (!isIdentifierText(name, getEmitScriptTarget(compilerOptions)) && (stringNamed || !isNumericLiteralName(name))) { + return factory.createStringLiteral(name, !!singleQuote); + } + if (isNumericLiteralName(name) && startsWith(name, "-")) { + return factory.createComputedPropertyName(factory.createPrefixUnaryExpression(SyntaxKind.MinusToken, factory.createNumericLiteral(-name))); + } + return createPropertyNameNodeForIdentifierOrLiteral(name, getEmitScriptTarget(compilerOptions), singleQuote, stringNamed, isMethod); + } + if (nameType.flags & TypeFlags.UniqueESSymbol) { + return factory.createComputedPropertyName(symbolToExpression((nameType as UniqueESSymbolType).symbol, context, SymbolFlags.Value)); + } + } + } + + function cloneNodeBuilderContext(context: NodeBuilderContext) { + // Make type parameters created within this context not consume the name outside this context + // The symbol serializer ends up creating many sibling scopes that all need "separate" contexts when + // it comes to naming things - within a normal `typeToTypeNode` call, the node builder only ever descends + // through the type tree, so the only cases where we could have used distinct sibling scopes was when there + // were multiple generic overloads with similar generated type parameter names + // The effect: + // When we write out + // export const x: (x: T) => T + // export const y: (x: T) => T + // we write it out like that, rather than as + // export const x: (x: T) => T + // export const y: (x: T_1) => T_1 + const oldMustCreateTypeParameterSymbolList = context.mustCreateTypeParameterSymbolList; + const oldMustCreateTypeParametersNamesLookups = context.mustCreateTypeParametersNamesLookups; + context.mustCreateTypeParameterSymbolList = true; + context.mustCreateTypeParametersNamesLookups = true; + const oldTypeParameterNames = context.typeParameterNames; + const oldTypeParameterNamesByText = context.typeParameterNamesByText; + const oldTypeParameterNamesByTextNextNameCount = context.typeParameterNamesByTextNextNameCount; + const oldTypeParameterSymbolList = context.typeParameterSymbolList; + return () => { + context.typeParameterNames = oldTypeParameterNames; + context.typeParameterNamesByText = oldTypeParameterNamesByText; + context.typeParameterNamesByTextNextNameCount = oldTypeParameterNamesByTextNextNameCount; + context.typeParameterSymbolList = oldTypeParameterSymbolList; + context.mustCreateTypeParameterSymbolList = oldMustCreateTypeParameterSymbolList; + context.mustCreateTypeParametersNamesLookups = oldMustCreateTypeParametersNamesLookups; + }; + } + + function getDeclarationWithTypeAnnotation(symbol: Symbol, enclosingDeclaration?: Node | undefined) { + return symbol.declarations && find(symbol.declarations, s => !!getNonlocalEffectiveTypeAnnotationNode(s) && (!enclosingDeclaration || !!findAncestor(s, n => n === enclosingDeclaration))); + } + + function existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing: TypeNode, type: Type) { + // In JS, you can say something like `Foo` and get a `Foo` implicitly - we don't want to preserve that original `Foo` in these cases, though. + if (!(getObjectFlags(type) & ObjectFlags.Reference)) return true; + if (!isTypeReferenceNode(existing)) return true; + // `type` is a reference type, and `existing` is a type reference node, but we still need to make sure they refer to the _same_ target type + // before we go comparing their type argument counts. + void getTypeFromTypeReference(existing); // call to ensure symbol is resolved + const symbol = getNodeLinks(existing).resolvedSymbol; + const existingTarget = symbol && getDeclaredTypeOfSymbol(symbol); + if (!existingTarget || existingTarget !== (type as TypeReference).target) return true; + return length(existing.typeArguments) >= getMinTypeArgumentCount((type as TypeReference).target.typeParameters); + } + + function getEnclosingDeclarationIgnoringFakeScope(enclosingDeclaration: Node) { + while (getNodeLinks(enclosingDeclaration).fakeScopeForSignatureDeclaration) { + enclosingDeclaration = enclosingDeclaration.parent; + } + return enclosingDeclaration; + } + + /** + * Unlike `typeToTypeNodeHelper`, this handles setting up the `AllowUniqueESSymbolType` flag + * so a `unique symbol` is returned when appropriate for the input symbol, rather than `typeof sym` + * @param context - The node builder context. Any reused nodes are checked to be pulled from within the scope of the context's enclosingDeclaration. + * @param declaration - The preferred declaration to pull existing type nodes from (the symbol will be used as a fallback to find any annotated declaration) + * @param type - The type to write; an existing annotation must match this type if it's used, otherwise this is the type serialized as a new type node + * @param symbol - The symbol is used both to find an existing annotation if declaration is not provided, and to determine if `unique symbol` should be printed + */ + function serializeTypeForDeclaration(context: NodeBuilderContext, declaration: Declaration | undefined, type: Type, symbol: Symbol) { + const addUndefined = declaration && (isParameter(declaration) || isJSDocParameterTag(declaration)) && requiresAddingImplicitUndefined(declaration); + const enclosingDeclaration = context.enclosingDeclaration; + const oldFlags = context.flags; + if (declaration && hasInferredType(declaration) && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) { + syntacticNodeBuilder.serializeTypeOfDeclaration(declaration, context); + } + context.flags |= NodeBuilderFlags.NoSyntacticPrinter; + if (enclosingDeclaration && (!isErrorType(type) || (context.flags & NodeBuilderFlags.AllowUnresolvedNames))) { + const declWithExistingAnnotation = declaration && getNonlocalEffectiveTypeAnnotationNode(declaration) + ? declaration + : getDeclarationWithTypeAnnotation(symbol); + if (declWithExistingAnnotation && !isFunctionLikeDeclaration(declWithExistingAnnotation) && !isGetAccessorDeclaration(declWithExistingAnnotation)) { + // try to reuse the existing annotation + const existing = getNonlocalEffectiveTypeAnnotationNode(declWithExistingAnnotation)!; + const result = !isTypePredicateNode(existing) && tryReuseExistingTypeNode(context, existing, type, declWithExistingAnnotation, addUndefined); + if (result) { + context.flags = oldFlags; + return result; + } + } + } + if ( + type.flags & TypeFlags.UniqueESSymbol && + type.symbol === symbol && (!context.enclosingDeclaration || some(symbol.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(context.enclosingDeclaration!))) + ) { + context.flags |= NodeBuilderFlags.AllowUniqueESSymbolType; + } + + const decl = declaration ?? symbol.valueDeclaration ?? symbol.declarations?.[0]; + const expr = decl && isDeclarationWithPossibleInnerTypeNodeReuse(decl) ? getPossibleTypeNodeReuseExpression(decl) : undefined; + + const result = expressionOrTypeToTypeNode(context, expr, type, addUndefined); + context.flags = oldFlags; + return result; + } + + function typeNodeIsEquivalentToType(annotatedDeclaration: Node | undefined, type: Type, typeFromTypeNode: Type) { + if (typeFromTypeNode === type) { + return true; + } + if (annotatedDeclaration && (isParameter(annotatedDeclaration) || isPropertySignature(annotatedDeclaration) || isPropertyDeclaration(annotatedDeclaration)) && annotatedDeclaration.questionToken) { + return getTypeWithFacts(type, TypeFacts.NEUndefined) === typeFromTypeNode; + } + return false; + } + + function serializeReturnTypeForSignature(context: NodeBuilderContext, signature: Signature) { + const suppressAny = context.flags & NodeBuilderFlags.SuppressAnyReturnType; + const flags = context.flags; + if (suppressAny) context.flags &= ~NodeBuilderFlags.SuppressAnyReturnType; // suppress only toplevel `any`s + let returnTypeNode: TypeNode | undefined; + const returnType = getReturnTypeOfSignature(signature); + if (returnType && !(suppressAny && isTypeAny(returnType))) { + if (signature.declaration && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) { + syntacticNodeBuilder.serializeReturnTypeForSignature(signature.declaration, context); + } + context.flags |= NodeBuilderFlags.NoSyntacticPrinter; + returnTypeNode = serializeReturnTypeForSignatureWorker(context, signature); + } + else if (!suppressAny) { + returnTypeNode = factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + context.flags = flags; + return returnTypeNode; + } + + function serializeReturnTypeForSignatureWorker(context: NodeBuilderContext, signature: Signature) { + const typePredicate = getTypePredicateOfSignature(signature); + const type = getReturnTypeOfSignature(signature); + if (context.enclosingDeclaration && (!isErrorType(type) || (context.flags & NodeBuilderFlags.AllowUnresolvedNames)) && signature.declaration && !nodeIsSynthesized(signature.declaration)) { + const annotation = signature.declaration && getNonlocalEffectiveReturnTypeAnnotationNode(signature.declaration); + // Default constructor signatures inherited from base classes return the derived class but have the base class declaration + // To ensure we don't serialize the wrong type we check that that return type of the signature corresponds to the declaration return type signature + if (annotation && getTypeFromTypeNode(context, annotation) === type) { + const result = tryReuseExistingTypeNodeHelper(context, annotation); + if (result) { + return result; + } + } + } + if (typePredicate) { + return typePredicateToTypePredicateNodeHelper(typePredicate, context); + } + const expr = signature.declaration && getPossibleTypeNodeReuseExpression(signature.declaration); + return expressionOrTypeToTypeNode(context, expr, type); + } + + function trackExistingEntityName(node: T, context: NodeBuilderContext) { + let introducesError = false; + const leftmost = getFirstIdentifier(node); + if (isInJSFile(node) && (isExportsIdentifier(leftmost) || isModuleExportsAccessExpression(leftmost.parent) || (isQualifiedName(leftmost.parent) && isModuleIdentifier(leftmost.parent.left) && isExportsIdentifier(leftmost.parent.right)))) { + introducesError = true; + return { introducesError, node }; + } + const meaning = getMeaningOfEntityNameReference(node); + let sym: Symbol | undefined; + if (isThisIdentifier(leftmost)) { + // `this` isn't a bindable identifier - skip resolution, find a relevant `this` symbol directly and avoid exhaustive scope traversal + sym = getSymbolOfDeclaration(getThisContainer(leftmost, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)); + if (isSymbolAccessible(sym, leftmost, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible) { + introducesError = true; + context.tracker.reportInaccessibleThisError(); + } + return { introducesError, node: attachSymbolToLeftmostIdentifier(node) as T }; + } + sym = resolveEntityName(leftmost, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true); + if ( + context.enclosingDeclaration && + !(sym && sym.flags & SymbolFlags.TypeParameter) + ) { + sym = getExportSymbolOfValueSymbolIfExported(sym); + // Some declarations may be transplanted to a new location. + // When this happens we need to make sure that the name has the same meaning at both locations + // We also check for the unknownSymbol because when we create a fake scope some parameters may actually not be usable + // either because they are the expanded rest parameter, + // or because they are the newly added parameters from the tuple, which might have different meanings in the original context + const symAtLocation = resolveEntityName(leftmost, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, context.enclosingDeclaration); + if ( + // Check for unusable parameters symbols + symAtLocation === unknownSymbol || + // If the symbol is not found, but was not found in the original scope either we probably have an error, don't reuse the node + (symAtLocation === undefined && sym !== undefined) || + // If the symbol is found both in declaration scope and in current scope then it shoudl point to the same reference + (symAtLocation && sym && !getSymbolIfSameReference(getExportSymbolOfValueSymbolIfExported(symAtLocation), sym)) + ) { + // In isolated declaration we will not do rest parameter expansion so there is no need to report on these. + if (symAtLocation !== unknownSymbol) { + context.tracker.reportInferenceFallback(node); + } + introducesError = true; + return { introducesError, node, sym }; + } + } + + if (sym) { + // If a parameter is resolvable in the current context it is also visible, so no need to go to symbol accesibility + if ( + sym.flags & SymbolFlags.FunctionScopedVariable + && sym.valueDeclaration + ) { + if (isPartOfParameterDeclaration(sym.valueDeclaration) || isJSDocParameterTag(sym.valueDeclaration)) { + return { introducesError, node: attachSymbolToLeftmostIdentifier(node) as T }; + } + } + if ( + !(sym.flags & SymbolFlags.TypeParameter) && // Type parameters are visible in the current context if they are are resolvable + !isDeclarationName(node) && + isSymbolAccessible(sym, context.enclosingDeclaration, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible + ) { + context.tracker.reportInferenceFallback(node); + introducesError = true; + } + else { + context.tracker.trackSymbol(sym, context.enclosingDeclaration, meaning); + } + return { introducesError, node: attachSymbolToLeftmostIdentifier(node) as T }; + } + + return { introducesError, node }; + + /** + * Attaches a `.symbol` member to an identifier, cloning it to do so, so symbol information + * is smuggled out for symbol display information. + */ + function attachSymbolToLeftmostIdentifier(node: Node): Node { + if (node === leftmost) { + const type = getDeclaredTypeOfSymbol(sym!); + const name = sym!.flags & SymbolFlags.TypeParameter ? typeParameterToName(type, context) : factory.cloneNode(node as Identifier); + name.symbol = sym!; // for quickinfo, which uses identifier symbol information + return setTextRange(context, setEmitFlags(name, EmitFlags.NoAsciiEscaping), node); + } + const updated = visitEachChildWorker(node, c => attachSymbolToLeftmostIdentifier(c), /*context*/ undefined); + if (updated !== node) { + setTextRange(context, updated, node); + } + return updated; + } + } + + function serializeTypeName(context: NodeBuilderContext, node: EntityName, isTypeOf?: boolean, typeArguments?: readonly TypeNode[]) { + const meaning = isTypeOf ? SymbolFlags.Value : SymbolFlags.Type; + const symbol = resolveEntityName(node, meaning, /*ignoreErrors*/ true); + if (!symbol) return undefined; + const resolvedSymbol = symbol.flags & SymbolFlags.Alias ? resolveAlias(symbol) : symbol; + if (isSymbolAccessible(symbol, context.enclosingDeclaration, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible) return undefined; + return symbolToTypeNode(resolvedSymbol, context, meaning, typeArguments); + } + + function canReuseTypeNode(context: NodeBuilderContext, existing: TypeNode) { + if (isInJSFile(existing)) { + if (isLiteralImportTypeNode(existing)) { + // Ensure resolvedSymbol is present + void getTypeFromImportTypeNode(existing); + const nodeSymbol = getNodeLinks(existing).resolvedSymbol; + return ( + !nodeSymbol || + !( + // The import type resolved using jsdoc fallback logic + (!existing.isTypeOf && !(nodeSymbol.flags & SymbolFlags.Type)) || + // The import type had type arguments autofilled by js fallback logic + !(length(existing.typeArguments) >= getMinTypeArgumentCount(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(nodeSymbol))) + ) + ); + } + } + if (isThisTypeNode(existing)) { + if (context.mapper === undefined) return true; + const type = getTypeFromTypeNode(context, existing, /*noMappedTypes*/ true); + return !!type; + } + if (isTypeReferenceNode(existing)) { + if (isConstTypeReference(existing)) return false; + const type = getTypeFromTypeReference(existing); + const symbol = getNodeLinks(existing).resolvedSymbol; + if (!symbol) return false; + if (symbol.flags & SymbolFlags.TypeParameter) { + const type = getDeclaredTypeOfSymbol(symbol); + if (context.mapper && getMappedType(type, context.mapper) !== type) { + return false; + } + } + if (isInJSDoc(existing)) { + return existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing, type) + && !getIntendedTypeFromJSDocTypeReference(existing) // We should probably allow the reuse of JSDoc reference types such as String Number etc + && (symbol.flags & SymbolFlags.Type); // JSDoc type annotations can reference values (meaning typeof value) as well as types. We only reuse type nodes + } + } + if ( + isTypeOperatorNode(existing) && + existing.operator === SyntaxKind.UniqueKeyword && + existing.type.kind === SyntaxKind.SymbolKeyword + ) { + const effectiveEnclosingContext = context.enclosingDeclaration && getEnclosingDeclarationIgnoringFakeScope(context.enclosingDeclaration); + return !!findAncestor(existing, n => n === effectiveEnclosingContext); + } + return true; + } + + function serializeExistingTypeNode(context: NodeBuilderContext, typeNode: TypeNode) { + const type = getTypeFromTypeNode(context, typeNode); + return typeToTypeNodeHelper(type, context); + } + + /** + * Do you mean to call this directly? You probably should use `tryReuseExistingTypeNode` instead, + * which performs sanity checking on the type before doing this. + */ + function tryReuseExistingTypeNodeHelper(context: NodeBuilderContext, existing: TypeNode) { + if (cancellationToken && cancellationToken.throwIfCancellationRequested) { + cancellationToken.throwIfCancellationRequested(); + } + let hadError = false; + const { finalizeBoundary, startRecoveryScope } = createRecoveryBoundary(); + const transformed = visitNode(existing, visitExistingNodeTreeSymbols, isTypeNode); + if (!finalizeBoundary()) { + return undefined; + } + context.approximateLength += existing.end - existing.pos; + return transformed; + + function visitExistingNodeTreeSymbols(node: Node): Node | undefined { + // If there was an error in a sibling node bail early, the result will be discarded anyway + if (hadError) return node; + const recover = startRecoveryScope(); + const onExitNewScope = isNewScopeNode(node) ? onEnterNewScope(node) : undefined; + const result = visitExistingNodeTreeSymbolsWorker(node); + onExitNewScope?.(); + + // If there was an error, maybe we can recover by serializing the actual type of the node + if (hadError) { + if (isTypeNode(node) && !isTypePredicateNode(node)) { + recover(); + return serializeExistingTypeNode(context, node); + } + return node; + } + // We want to clone the subtree, so when we mark it up with __pos and __end in quickfixes, + // we don't get odd behavior because of reused nodes. We also need to clone to _remove_ + // the position information if the node comes from a different file than the one the node builder + // is set to build for (even though we are reusing the node structure, the position information + // would make the printer print invalid spans for literals and identifiers, and the formatter would + // choke on the mismatched positonal spans between a parent and an injected child from another file). + return result ? setTextRange(context, result, node) : undefined; + } + + function createRecoveryBoundary() { + let trackedSymbols: TrackedSymbol[]; + let unreportedErrors: (() => void)[]; + const oldTracker = context.tracker; + const oldTrackedSymbols = context.trackedSymbols; + context.trackedSymbols = undefined; + const oldEncounteredError = context.encounteredError; + context.tracker = new SymbolTrackerImpl(context, { + ...oldTracker.inner, + reportCyclicStructureError() { + markError(() => oldTracker.reportCyclicStructureError()); + }, + reportInaccessibleThisError() { + markError(() => oldTracker.reportInaccessibleThisError()); + }, + reportInaccessibleUniqueSymbolError() { + markError(() => oldTracker.reportInaccessibleUniqueSymbolError()); + }, + reportLikelyUnsafeImportRequiredError(specifier) { + markError(() => oldTracker.reportLikelyUnsafeImportRequiredError(specifier)); + }, + reportNonSerializableProperty(name) { + markError(() => oldTracker.reportNonSerializableProperty(name)); + }, + trackSymbol(sym, decl, meaning) { + (trackedSymbols ??= []).push([sym, decl, meaning]); + return false; + }, + moduleResolverHost: context.tracker.moduleResolverHost, + }, context.tracker.moduleResolverHost); + + return { + startRecoveryScope, + finalizeBoundary, + }; + + function markError(unreportedError: () => void) { + hadError = true; + (unreportedErrors ??= []).push(unreportedError); + } + + function startRecoveryScope() { + const trackedSymbolsTop = trackedSymbols?.length ?? 0; + const unreportedErrorsTop = unreportedErrors?.length ?? 0; + return () => { + hadError = false; + // Reset the tracked symbols to before the error + if (trackedSymbols) { + trackedSymbols.length = trackedSymbolsTop; + } + if (unreportedErrors) { + unreportedErrors.length = unreportedErrorsTop; + } + }; + } + + function finalizeBoundary() { + context.tracker = oldTracker; + context.trackedSymbols = oldTrackedSymbols; + context.encounteredError = oldEncounteredError; + + unreportedErrors?.forEach(fn => fn()); + if (hadError) { + return false; + } + trackedSymbols?.forEach( + ([symbol, enclosingDeclaration, meaning]) => + context.tracker.trackSymbol( + symbol, + enclosingDeclaration, + meaning, + ), + ); + return true; + } + } + function onEnterNewScope(node: IntroducesNewScopeNode | ConditionalTypeNode) { + return enterNewScope(context, node, getParametersInScope(node), getTypeParametersInScope(node)); + } + + function tryVisitSimpleTypeNode(node: TypeNode): TypeNode | undefined { + const innerNode = skipTypeParentheses(node); + switch (innerNode.kind) { + case SyntaxKind.TypeReference: + return tryVisitTypeReference(innerNode as TypeReferenceNode); + case SyntaxKind.TypeQuery: + return tryVisitTypeQuery(innerNode as TypeQueryNode); + case SyntaxKind.IndexedAccessType: + return tryVisitIndexedAccess(innerNode as IndexedAccessTypeNode); + case SyntaxKind.TypeOperator: + const typeOperatorNode = innerNode as TypeOperatorNode; + if (typeOperatorNode.operator === SyntaxKind.KeyOfKeyword) { + return tryVisitKeyOf(typeOperatorNode); + } + } + return visitNode(node, visitExistingNodeTreeSymbols, isTypeNode); + } + + function tryVisitIndexedAccess(node: IndexedAccessTypeNode): TypeNode | undefined { + const resultObjectType = tryVisitSimpleTypeNode(node.objectType); + if (resultObjectType === undefined) { + return undefined; + } + return factory.updateIndexedAccessTypeNode(node, resultObjectType, visitNode(node.indexType, visitExistingNodeTreeSymbols, isTypeNode)!); + } + + function tryVisitKeyOf(node: TypeOperatorNode): TypeNode | undefined { + Debug.assertEqual(node.operator, SyntaxKind.KeyOfKeyword); + const type = tryVisitSimpleTypeNode(node.type); + if (type === undefined) { + return undefined; + } + return factory.updateTypeOperatorNode(node, type); + } + + function tryVisitTypeQuery(node: TypeQueryNode): TypeNode | undefined { + const { introducesError, node: exprName } = trackExistingEntityName(node.exprName, context); + if (!introducesError) { + return factory.updateTypeQueryNode( + node, + exprName, + visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode), + ); + } + + const serializedName = serializeTypeName(context, node.exprName, /*isTypeOf*/ true); + if (serializedName) { + return setTextRange(context, serializedName, node.exprName); + } + } + + function tryVisitTypeReference(node: TypeReferenceNode): TypeNode | undefined { + if (canReuseTypeNode(context, node)) { + const { introducesError, node: newName } = trackExistingEntityName(node.typeName, context); + const typeArguments = visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode); + + if (!introducesError) { + const updated = factory.updateTypeReferenceNode( + node, + newName, + typeArguments, + ); + return setTextRange(context, updated, node); + } + else { + const serializedName = serializeTypeName(context, node.typeName, /*isTypeOf*/ false, typeArguments); + if (serializedName) { + return setTextRange(context, serializedName, node.typeName); + } + } + } + } + + function visitExistingNodeTreeSymbolsWorker(node: Node): Node | undefined { + if (isJSDocTypeExpression(node)) { + // Unwrap JSDocTypeExpressions + return visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode); + } + // We don't _actually_ support jsdoc namepath types, emit `any` instead + if (isJSDocAllType(node) || node.kind === SyntaxKind.JSDocNamepathType) { + return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + if (isJSDocUnknownType(node)) { + return factory.createKeywordTypeNode(SyntaxKind.UnknownKeyword); + } + if (isJSDocNullableType(node)) { + return factory.createUnionTypeNode([visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)!, factory.createLiteralTypeNode(factory.createNull())]); + } + if (isJSDocOptionalType(node)) { + return factory.createUnionTypeNode([visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)!, factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); + } + if (isJSDocNonNullableType(node)) { + return visitNode(node.type, visitExistingNodeTreeSymbols); + } + if (isJSDocVariadicType(node)) { + return factory.createArrayTypeNode(visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)!); + } + if (isJSDocTypeLiteral(node)) { + return factory.createTypeLiteralNode(map(node.jsDocPropertyTags, t => { + const name = visitNode(isIdentifier(t.name) ? t.name : t.name.right, visitExistingNodeTreeSymbols, isIdentifier)!; + const typeViaParent = getTypeOfPropertyOfType(getTypeFromTypeNode(context, node), name.escapedText); + const overrideTypeNode = typeViaParent && t.typeExpression && getTypeFromTypeNode(context, t.typeExpression.type) !== typeViaParent ? typeToTypeNodeHelper(typeViaParent, context) : undefined; + + return factory.createPropertySignature( + /*modifiers*/ undefined, + name, + t.isBracketed || t.typeExpression && isJSDocOptionalType(t.typeExpression.type) ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + overrideTypeNode || (t.typeExpression && visitNode(t.typeExpression.type, visitExistingNodeTreeSymbols, isTypeNode)) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), + ); + })); + } + if (isTypeReferenceNode(node) && isIdentifier(node.typeName) && node.typeName.escapedText === "") { + return setOriginalNode(factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), node); + } + if ((isExpressionWithTypeArguments(node) || isTypeReferenceNode(node)) && isJSDocIndexSignature(node)) { + return factory.createTypeLiteralNode([factory.createIndexSignature( + /*modifiers*/ undefined, + [factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + "x", + /*questionToken*/ undefined, + visitNode(node.typeArguments![0], visitExistingNodeTreeSymbols, isTypeNode), + )], + visitNode(node.typeArguments![1], visitExistingNodeTreeSymbols, isTypeNode), + )]); + } + if (isJSDocFunctionType(node)) { + if (isJSDocConstructSignature(node)) { + let newTypeNode: TypeNode | undefined; + return factory.createConstructorTypeNode( + /*modifiers*/ undefined, + visitNodes(node.typeParameters, visitExistingNodeTreeSymbols, isTypeParameterDeclaration), + mapDefined(node.parameters, (p, i) => + p.name && isIdentifier(p.name) && p.name.escapedText === "new" ? (newTypeNode = p.type, undefined) : factory.createParameterDeclaration( + /*modifiers*/ undefined, + getEffectiveDotDotDotForParameter(p), + setTextRange(context, factory.createIdentifier(getNameForJSDocFunctionParameter(p, i)), p), + factory.cloneNode(p.questionToken), + visitNode(p.type, visitExistingNodeTreeSymbols, isTypeNode), + /*initializer*/ undefined, + )), + visitNode(newTypeNode || node.type, visitExistingNodeTreeSymbols, isTypeNode) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), + ); + } + else { + return factory.createFunctionTypeNode( + visitNodes(node.typeParameters, visitExistingNodeTreeSymbols, isTypeParameterDeclaration), + map(node.parameters, (p, i) => + factory.createParameterDeclaration( + /*modifiers*/ undefined, + getEffectiveDotDotDotForParameter(p), + setTextRange(context, factory.createIdentifier(getNameForJSDocFunctionParameter(p, i)), p), + factory.cloneNode(p.questionToken), + visitNode(p.type, visitExistingNodeTreeSymbols, isTypeNode), + /*initializer*/ undefined, + )), + visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), + ); + } + } + if (isThisTypeNode(node)) { + if (canReuseTypeNode(context, node)) { + return node; + } + hadError = true; + return node; + } + if (isTypeParameterDeclaration(node)) { + return factory.updateTypeParameterDeclaration( + node, + visitNodes(node.modifiers, visitExistingNodeTreeSymbols, isModifier), + setTextRange(context, typeParameterToName(getDeclaredTypeOfSymbol(getSymbolOfDeclaration(node)), context), node), + visitNode(node.constraint, visitExistingNodeTreeSymbols, isTypeNode), + visitNode(node.default, visitExistingNodeTreeSymbols, isTypeNode), + ); + } + + if (isIndexedAccessTypeNode(node)) { + const result = tryVisitIndexedAccess(node); + if (!result) { + hadError = true; + return node; + } + return result; + } + + if (isTypeReferenceNode(node)) { + const result = tryVisitTypeReference(node); + if (result) { + return result; + } + hadError = true; + return node; + } + if (isLiteralImportTypeNode(node)) { + const nodeSymbol = getNodeLinks(node).resolvedSymbol; + if ( + isInJSDoc(node) && + nodeSymbol && + ( + // The import type resolved using jsdoc fallback logic + (!node.isTypeOf && !(nodeSymbol.flags & SymbolFlags.Type)) || + // The import type had type arguments autofilled by js fallback logic + !(length(node.typeArguments) >= getMinTypeArgumentCount(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(nodeSymbol))) + ) + ) { + return setTextRange(context, typeToTypeNodeHelper(getTypeFromTypeNode(context, node), context), node); + } + return factory.updateImportTypeNode( + node, + factory.updateLiteralTypeNode(node.argument, rewriteModuleSpecifier(node, node.argument.literal)), + visitNode(node.attributes, visitExistingNodeTreeSymbols, isImportAttributes), + visitNode(node.qualifier, visitExistingNodeTreeSymbols, isEntityName), + visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode), + node.isTypeOf, + ); + } + if (isNamedDeclaration(node) && node.name.kind === SyntaxKind.ComputedPropertyName && !isLateBindableName(node.name)) { + if (!(context.flags & NodeBuilderFlags.AllowUnresolvedNames && hasDynamicName(node) && isEntityNameExpression(node.name.expression) && checkComputedPropertyName(node.name).flags & TypeFlags.Any)) { + return undefined; + } + } + if ( + (isFunctionLike(node) && !node.type) + || (isPropertyDeclaration(node) && !node.type && !node.initializer) + || (isPropertySignature(node) && !node.type && !node.initializer) + || (isParameter(node) && !node.type && !node.initializer) + ) { + let visited = visitEachChild(node, visitExistingNodeTreeSymbols); + if (visited === node) { + visited = setTextRange(context, factory.cloneNode(node), node); + } + (visited as Mutable).type = factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + if (isParameter(node)) { + (visited as Mutable).modifiers = undefined; + } + return visited; + } + if (isTypeQueryNode(node)) { + const result = tryVisitTypeQuery(node); + if (!result) { + hadError = true; + return node; + } + return result; + } + if (isComputedPropertyName(node) && isEntityNameExpression(node.expression)) { + const { node: result, introducesError } = trackExistingEntityName(node.expression, context); + if (!introducesError) { + return factory.updateComputedPropertyName(node, result); + } + else { + const type = getWidenedType(getRegularTypeOfExpression(node.expression)); + const computedPropertyNameType = typeToTypeNodeHelper(type, context); + let literal; + if (isLiteralTypeNode(computedPropertyNameType)) { + literal = computedPropertyNameType.literal; + } + else { + const evaluated = evaluateEntityNameExpression(node.expression); + const literalNode = typeof evaluated.value === "string" ? factory.createStringLiteral(evaluated.value, /*isSingleQuote*/ undefined) : + typeof evaluated.value === "number" ? factory.createNumericLiteral(evaluated.value, /*numericLiteralFlags*/ 0) : + undefined; + if (!literalNode) { + if (isImportTypeNode(computedPropertyNameType)) { + trackComputedName(node.expression, context.enclosingDeclaration, context); + } + return node; + } + literal = literalNode; + } + if (literal.kind === SyntaxKind.StringLiteral && isIdentifierText(literal.text, getEmitScriptTarget(compilerOptions))) { + return factory.createIdentifier(literal.text); + } + if (literal.kind === SyntaxKind.NumericLiteral && !literal.text.startsWith("-")) { + return literal; + } + return factory.updateComputedPropertyName(node, literal); + } + } + if (isTypePredicateNode(node)) { + let parameterName; + if (isIdentifier(node.parameterName)) { + const { node: result, introducesError } = trackExistingEntityName(node.parameterName, context); + // Should not usually happen the only case is when a type predicate comes from a JSDoc type annotation with it's own parameter symbol definition. + // /** @type {(v: unknown) => v is undefined} */ + // const isUndef = v => v === undefined; + hadError = hadError || introducesError; + parameterName = result; + } + else { + parameterName = factory.cloneNode(node.parameterName); + } + return factory.updateTypePredicateNode(node, factory.cloneNode(node.assertsModifier), parameterName, visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)); + } + + if (isTupleTypeNode(node) || isTypeLiteralNode(node) || isMappedTypeNode(node)) { + const visited = visitEachChild(node, visitExistingNodeTreeSymbols); + const clone = setTextRange(context, visited === node ? factory.cloneNode(node) : visited, node); + const flags = getEmitFlags(clone); + setEmitFlags(clone, flags | (context.flags & NodeBuilderFlags.MultilineObjectLiterals && isTypeLiteralNode(node) ? 0 : EmitFlags.SingleLine)); + return clone; + } + if (isStringLiteral(node) && !!(context.flags & NodeBuilderFlags.UseSingleQuotesForStringLiteralType) && !node.singleQuote) { + const clone = factory.cloneNode(node); + (clone as Mutable).singleQuote = true; + return clone; + } + if (isConditionalTypeNode(node)) { + const checkType = visitNode(node.checkType, visitExistingNodeTreeSymbols, isTypeNode)!; + + const disposeScope = onEnterNewScope(node); + const extendType = visitNode(node.extendsType, visitExistingNodeTreeSymbols, isTypeNode)!; + const trueType = visitNode(node.trueType, visitExistingNodeTreeSymbols, isTypeNode)!; + disposeScope(); + const falseType = visitNode(node.falseType, visitExistingNodeTreeSymbols, isTypeNode)!; + return factory.updateConditionalTypeNode( + node, + checkType, + extendType, + trueType, + falseType, + ); + } + + if (isTypeOperatorNode(node)) { + if (node.operator === SyntaxKind.UniqueKeyword && node.type.kind === SyntaxKind.SymbolKeyword) { + if (!canReuseTypeNode(context, node)) { + hadError = true; + return node; + } + } + else if (node.operator === SyntaxKind.KeyOfKeyword) { + const result = tryVisitKeyOf(node); + if (!result) { + hadError = true; + return node; + } + return result; + } + } + + return visitEachChild(node, visitExistingNodeTreeSymbols); + + function visitEachChild(node: T, visitor: Visitor): T; + function visitEachChild(node: T | undefined, visitor: Visitor): T | undefined; + function visitEachChild(node: T | undefined, visitor: Visitor): T | undefined { + const nonlocalNode = !context.enclosingFile || context.enclosingFile !== getSourceFileOfNode(node); + return visitEachChildWorker(node, visitor, /*context*/ undefined, nonlocalNode ? visitNodesWithoutCopyingPositions : undefined); + } + + function visitNodesWithoutCopyingPositions( + nodes: NodeArray | undefined, + visitor: Visitor, + test?: (node: Node) => boolean, + start?: number, + count?: number, + ): NodeArray | undefined { + let result = visitNodes(nodes, visitor, test, start, count); + if (result) { + if (result.pos !== -1 || result.end !== -1) { + if (result === nodes) { + result = factory.createNodeArray(nodes, nodes.hasTrailingComma); + } + setTextRangePosEnd(result, -1, -1); + } + } + return result; + } + + function getEffectiveDotDotDotForParameter(p: ParameterDeclaration) { + return p.dotDotDotToken || (p.type && isJSDocVariadicType(p.type) ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined); + } + + /** Note that `new:T` parameters are not handled, but should be before calling this function. */ + function getNameForJSDocFunctionParameter(p: ParameterDeclaration, index: number) { + return p.name && isIdentifier(p.name) && p.name.escapedText === "this" ? "this" + : getEffectiveDotDotDotForParameter(p) ? `args` + : `arg${index}`; + } + + function rewriteModuleSpecifier(parent: ImportTypeNode, lit: StringLiteral) { + if (context.bundled || context.enclosingFile !== getSourceFileOfNode(lit)) { + let name = lit.text; + const nodeSymbol = getNodeLinks(node).resolvedSymbol; + const meaning = parent.isTypeOf ? SymbolFlags.Value : SymbolFlags.Type; + const parentSymbol = nodeSymbol + && isSymbolAccessible(nodeSymbol, context.enclosingDeclaration, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility === SymbolAccessibility.Accessible + && lookupSymbolChain(nodeSymbol, context, meaning, /*yieldModuleSymbol*/ true)[0]; + if (parentSymbol && isExternalModuleSymbol(parentSymbol)) { + name = getSpecifierForModuleSymbol(parentSymbol, context); + } + else { + const targetFile = getExternalModuleFileFromDeclaration(parent); + if (targetFile) { + name = getSpecifierForModuleSymbol(targetFile.symbol, context); + } + } + if (name.includes("/node_modules/")) { + context.encounteredError = true; + if (context.tracker.reportLikelyUnsafeImportRequiredError) { + context.tracker.reportLikelyUnsafeImportRequiredError(name); + } + } + if (name !== lit.text) { + return setOriginalNode(factory.createStringLiteral(name), lit); + } + } + return visitNode(lit, visitExistingNodeTreeSymbols, isStringLiteral)!; + } + } + } + + function symbolTableToDeclarationStatements(symbolTable: SymbolTable, context: NodeBuilderContext): Statement[] { + const serializePropertySymbolForClass = makeSerializePropertySymbol(factory.createPropertyDeclaration, SyntaxKind.MethodDeclaration, /*useAccessors*/ true); + const serializePropertySymbolForInterfaceWorker = makeSerializePropertySymbol((mods, name, question, type) => factory.createPropertySignature(mods, name, question, type), SyntaxKind.MethodSignature, /*useAccessors*/ false); + + // TODO: Use `setOriginalNode` on original declaration names where possible so these declarations see some kind of + // declaration mapping + + // We save the enclosing declaration off here so it's not adjusted by well-meaning declaration + // emit codepaths which want to apply more specific contexts (so we can still refer to the root real declaration + // we're trying to emit from later on) + const enclosingDeclaration = context.enclosingDeclaration!; + let results: Statement[] = []; + const visitedSymbols = new Set(); + const deferredPrivatesStack: Map[] = []; + const oldcontext = context; + context = { + ...oldcontext, + usedSymbolNames: new Set(oldcontext.usedSymbolNames), + remappedSymbolNames: new Map(), + remappedSymbolReferences: new Map(oldcontext.remappedSymbolReferences?.entries()), + tracker: undefined!, + }; + const tracker: SymbolTracker = { + ...oldcontext.tracker.inner, + trackSymbol: (sym, decl, meaning) => { + if (context.remappedSymbolNames?.has(getSymbolId(sym))) return false; // If the context has a remapped name for the symbol, it *should* mean it's been made visible + const accessibleResult = isSymbolAccessible(sym, decl, meaning, /*shouldComputeAliasesToMakeVisible*/ false); + if (accessibleResult.accessibility === SymbolAccessibility.Accessible) { + // Lookup the root symbol of the chain of refs we'll use to access it and serialize it + const chain = lookupSymbolChainWorker(sym, context, meaning); + if (!(sym.flags & SymbolFlags.Property)) { + // Only include referenced privates in the same file. Weird JS aliases may expose privates + // from other files - assume JS transforms will make those available via expected means + const root = chain[0]; + const contextFile = getSourceFileOfNode(oldcontext.enclosingDeclaration); + if (some(root.declarations, d => getSourceFileOfNode(d) === contextFile)) { + includePrivateSymbol(root); + } + } + } + else if (oldcontext.tracker.inner?.trackSymbol) { + return oldcontext.tracker.inner.trackSymbol(sym, decl, meaning); + } + return false; + }, + }; + context.tracker = new SymbolTrackerImpl(context, tracker, oldcontext.tracker.moduleResolverHost); + forEachEntry(symbolTable, (symbol, name) => { + const baseName = unescapeLeadingUnderscores(name); + void getInternalSymbolName(symbol, baseName); // Called to cache values into `usedSymbolNames` and `remappedSymbolNames` + }); + let addingDeclare = !context.bundled; + const exportEquals = symbolTable.get(InternalSymbolName.ExportEquals); + if (exportEquals && symbolTable.size > 1 && exportEquals.flags & (SymbolFlags.Alias | SymbolFlags.Module)) { + symbolTable = createSymbolTable(); + // Remove extraneous elements from root symbol table (they'll be mixed back in when the target of the `export=` is looked up) + symbolTable.set(InternalSymbolName.ExportEquals, exportEquals); + } + + visitSymbolTable(symbolTable); + return mergeRedundantStatements(results); + + function isIdentifierAndNotUndefined(node: Node | undefined): node is Identifier { + return !!node && node.kind === SyntaxKind.Identifier; + } + + function getNamesOfDeclaration(statement: Statement): Identifier[] { + if (isVariableStatement(statement)) { + return filter(map(statement.declarationList.declarations, getNameOfDeclaration), isIdentifierAndNotUndefined); + } + return filter([getNameOfDeclaration(statement as DeclarationStatement)], isIdentifierAndNotUndefined); + } + + function flattenExportAssignedNamespace(statements: Statement[]) { + const exportAssignment = find(statements, isExportAssignment); + const nsIndex = findIndex(statements, isModuleDeclaration); + let ns = nsIndex !== -1 ? statements[nsIndex] as ModuleDeclaration : undefined; + if ( + ns && exportAssignment && exportAssignment.isExportEquals && + isIdentifier(exportAssignment.expression) && isIdentifier(ns.name) && idText(ns.name) === idText(exportAssignment.expression) && + ns.body && isModuleBlock(ns.body) + ) { + // Pass 0: Correct situations where a module has both an `export = ns` and multiple top-level exports by stripping the export modifiers from + // the top-level exports and exporting them in the targeted ns, as can occur when a js file has both typedefs and `module.export` assignments + const excessExports = filter(statements, s => !!(getEffectiveModifierFlags(s) & ModifierFlags.Export)); + const name = ns.name; + let body = ns.body; + if (length(excessExports)) { + ns = factory.updateModuleDeclaration( + ns, + ns.modifiers, + ns.name, + body = factory.updateModuleBlock( + body, + factory.createNodeArray([ + ...ns.body.statements, + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(map(flatMap(excessExports, e => getNamesOfDeclaration(e)), id => factory.createExportSpecifier(/*isTypeOnly*/ false, /*propertyName*/ undefined, id))), + /*moduleSpecifier*/ undefined, + ), + ]), + ), + ); + statements = [...statements.slice(0, nsIndex), ns, ...statements.slice(nsIndex + 1)]; + } + + // Pass 1: Flatten `export namespace _exports {} export = _exports;` so long as the `export=` only points at a single namespace declaration + if (!find(statements, s => s !== ns && nodeHasName(s, name))) { + results = []; + // If the namespace contains no export assignments or declarations, and no declarations flagged with `export`, then _everything_ is exported - + // to respect this as the top level, we need to add an `export` modifier to everything + const mixinExportFlag = !some(body.statements, s => hasSyntacticModifier(s, ModifierFlags.Export) || isExportAssignment(s) || isExportDeclaration(s)); + forEach(body.statements, s => { + addResult(s, mixinExportFlag ? ModifierFlags.Export : ModifierFlags.None); // Recalculates the ambient (and export, if applicable from above) flag + }); + statements = [...filter(statements, s => s !== ns && s !== exportAssignment), ...results]; + } + } + return statements; + } + + function mergeExportDeclarations(statements: Statement[]) { + // Pass 2: Combine all `export {}` declarations + const exports = filter(statements, d => isExportDeclaration(d) && !d.moduleSpecifier && !!d.exportClause && isNamedExports(d.exportClause)) as ExportDeclaration[]; + if (length(exports) > 1) { + const nonExports = filter(statements, d => !isExportDeclaration(d) || !!d.moduleSpecifier || !d.exportClause); + statements = [ + ...nonExports, + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(flatMap(exports, e => cast(e.exportClause, isNamedExports).elements)), + /*moduleSpecifier*/ undefined, + ), + ]; + } + // Pass 2b: Also combine all `export {} from "..."` declarations as needed + const reexports = filter(statements, d => isExportDeclaration(d) && !!d.moduleSpecifier && !!d.exportClause && isNamedExports(d.exportClause)) as ExportDeclaration[]; + if (length(reexports) > 1) { + const groups = group(reexports, decl => isStringLiteral(decl.moduleSpecifier!) ? ">" + decl.moduleSpecifier.text : ">"); + if (groups.length !== reexports.length) { + for (const group of groups) { + if (group.length > 1) { + // remove group members from statements and then merge group members and add back to statements + statements = [ + ...filter(statements, s => !group.includes(s as ExportDeclaration)), + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(flatMap(group, e => cast(e.exportClause, isNamedExports).elements)), + group[0].moduleSpecifier, + ), + ]; + } + } + } + } + return statements; + } + + function inlineExportModifiers(statements: Statement[]) { + // Pass 3: Move all `export {}`'s to `export` modifiers where possible + const index = findIndex(statements, d => isExportDeclaration(d) && !d.moduleSpecifier && !d.attributes && !!d.exportClause && isNamedExports(d.exportClause)); + if (index >= 0) { + const exportDecl = statements[index] as ExportDeclaration & { readonly exportClause: NamedExports; }; + const replacements = mapDefined(exportDecl.exportClause.elements, e => { + if (!e.propertyName && e.name.kind !== SyntaxKind.StringLiteral) { + // export {name} - look thru `statements` for `name`, and if all results can take an `export` modifier, do so and filter it + const name = e.name; + const indices = indicesOf(statements); + const associatedIndices = filter(indices, i => nodeHasName(statements[i], name)); + if (length(associatedIndices) && every(associatedIndices, i => canHaveExportModifier(statements[i]))) { + for (const index of associatedIndices) { + statements[index] = addExportModifier(statements[index] as Extract); + } + return undefined; + } + } + return e; + }); + if (!length(replacements)) { + // all clauses removed, remove the export declaration + orderedRemoveItemAt(statements, index); + } + else { + // some items filtered, others not - update the export declaration + statements[index] = factory.updateExportDeclaration( + exportDecl, + exportDecl.modifiers, + exportDecl.isTypeOnly, + factory.updateNamedExports( + exportDecl.exportClause, + replacements, + ), + exportDecl.moduleSpecifier, + exportDecl.attributes, + ); + } + } + return statements; + } + + function mergeRedundantStatements(statements: Statement[]) { + statements = flattenExportAssignedNamespace(statements); + statements = mergeExportDeclarations(statements); + statements = inlineExportModifiers(statements); + + // Not a cleanup, but as a final step: If there is a mix of `export` and non-`export` declarations, but no `export =` or `export {}` add a `export {};` so + // declaration privacy is respected. + if ( + enclosingDeclaration && + ((isSourceFile(enclosingDeclaration) && isExternalOrCommonJsModule(enclosingDeclaration)) || isModuleDeclaration(enclosingDeclaration)) && + (!some(statements, isExternalModuleIndicator) || (!hasScopeMarker(statements) && some(statements, needsScopeMarker))) + ) { + statements.push(createEmptyExports(factory)); + } + return statements; + } + + function addExportModifier(node: Extract) { + const flags = (getEffectiveModifierFlags(node) | ModifierFlags.Export) & ~ModifierFlags.Ambient; + return factory.replaceModifiers(node, flags); + } + + function removeExportModifier(node: Extract) { + const flags = getEffectiveModifierFlags(node) & ~ModifierFlags.Export; + return factory.replaceModifiers(node, flags); + } + + function visitSymbolTable(symbolTable: SymbolTable, suppressNewPrivateContext?: boolean, propertyAsAlias?: boolean) { + if (!suppressNewPrivateContext) { + deferredPrivatesStack.push(new Map()); + } + symbolTable.forEach((symbol: Symbol) => { + serializeSymbol(symbol, /*isPrivate*/ false, !!propertyAsAlias); + }); + if (!suppressNewPrivateContext) { + // deferredPrivates will be filled up by visiting the symbol table + // And will continue to iterate as elements are added while visited `deferredPrivates` + // (As that's how a map iterator is defined to work) + deferredPrivatesStack[deferredPrivatesStack.length - 1].forEach((symbol: Symbol) => { + serializeSymbol(symbol, /*isPrivate*/ true, !!propertyAsAlias); + }); + deferredPrivatesStack.pop(); + } + } + + function serializeSymbol(symbol: Symbol, isPrivate: boolean, propertyAsAlias: boolean): void { + void getPropertiesOfType(getTypeOfSymbol(symbol)); // resolve symbol's type and properties, which should trigger any required merges + // cache visited list based on merged symbol, since we want to use the unmerged top-level symbol, but + // still skip reserializing it if we encounter the merged product later on + const visitedSym = getMergedSymbol(symbol); + if (visitedSymbols.has(getSymbolId(visitedSym))) { + return; // Already printed + } + visitedSymbols.add(getSymbolId(visitedSym)); + // Only actually serialize symbols within the correct enclosing declaration, otherwise do nothing with the out-of-context symbol + const skipMembershipCheck = !isPrivate; // We only call this on exported symbols when we know they're in the correct scope + if (skipMembershipCheck || (!!length(symbol.declarations) && some(symbol.declarations, d => !!findAncestor(d, n => n === enclosingDeclaration)))) { + const scopeCleanup = cloneNodeBuilderContext(context); + serializeSymbolWorker(symbol, isPrivate, propertyAsAlias); + scopeCleanup(); + } + } + + // Synthesize declarations for a symbol - might be an Interface, a Class, a Namespace, a Type, a Variable (const, let, or var), an Alias + // or a merge of some number of those. + // An interesting challenge is ensuring that when classes merge with namespaces and interfaces, is keeping + // each symbol in only one of the representations + // Also, synthesizing a default export of some kind + // If it's an alias: emit `export default ref` + // If it's a property: emit `export default _default` with a `_default` prop + // If it's a class/interface/function: emit a class/interface/function with a `default` modifier + // These forms can merge, eg (`export default 12; export default interface A {}`) + function serializeSymbolWorker(symbol: Symbol, isPrivate: boolean, propertyAsAlias: boolean, escapedSymbolName = symbol.escapedName): void { + const symbolName = unescapeLeadingUnderscores(escapedSymbolName); + const isDefault = escapedSymbolName === InternalSymbolName.Default; + if (isPrivate && !(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier) && isStringANonContextualKeyword(symbolName) && !isDefault) { + // Oh no. We cannot use this symbol's name as it's name... It's likely some jsdoc had an invalid name like `export` or `default` :( + context.encounteredError = true; + // TODO: Issue error via symbol tracker? + return; // If we need to emit a private with a keyword name, we're done for, since something else will try to refer to it by that name + } + let needsPostExportDefault = isDefault && !!( + symbol.flags & SymbolFlags.ExportDoesNotSupportDefaultModifier + || (symbol.flags & SymbolFlags.Function && length(getPropertiesOfType(getTypeOfSymbol(symbol)))) + ) && !(symbol.flags & SymbolFlags.Alias); // An alias symbol should preclude needing to make an alias ourselves + let needsExportDeclaration = !needsPostExportDefault && !isPrivate && isStringANonContextualKeyword(symbolName) && !isDefault; + // `serializeVariableOrProperty` will handle adding the export declaration if it is run (since `getInternalSymbolName` will create the name mapping), so we need to ensuer we unset `needsExportDeclaration` if it is + if (needsPostExportDefault || needsExportDeclaration) { + isPrivate = true; + } + const modifierFlags = (!isPrivate ? ModifierFlags.Export : 0) | (isDefault && !needsPostExportDefault ? ModifierFlags.Default : 0); + const isConstMergedWithNS = symbol.flags & SymbolFlags.Module && + symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.FunctionScopedVariable | SymbolFlags.Property) && + escapedSymbolName !== InternalSymbolName.ExportEquals; + const isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol); + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method) || isConstMergedWithNSPrintableAsSignatureMerge) { + serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + if (symbol.flags & SymbolFlags.TypeAlias) { + serializeTypeAlias(symbol, symbolName, modifierFlags); + } + // Need to skip over export= symbols below - json source files get a single `Property` flagged + // symbol of name `export=` which needs to be handled like an alias. It's not great, but it is what it is. + if ( + symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.FunctionScopedVariable | SymbolFlags.Property | SymbolFlags.Accessor) + && escapedSymbolName !== InternalSymbolName.ExportEquals + && !(symbol.flags & SymbolFlags.Prototype) + && !(symbol.flags & SymbolFlags.Class) + && !(symbol.flags & SymbolFlags.Method) + && !isConstMergedWithNSPrintableAsSignatureMerge + ) { + if (propertyAsAlias) { + const createdExport = serializeMaybeAliasAssignment(symbol); + if (createdExport) { + needsExportDeclaration = false; + needsPostExportDefault = false; + } + } + else { + const type = getTypeOfSymbol(symbol); + const localName = getInternalSymbolName(symbol, symbolName); + if (type.symbol && type.symbol !== symbol && type.symbol.flags & SymbolFlags.Function && some(type.symbol.declarations, isFunctionExpressionOrArrowFunction) && (type.symbol.members?.size || type.symbol.exports?.size)) { + // assignment of a anonymous expando/class-like function, the func/ns/merge branch below won't trigger, + // and the assignment form has to reference the unreachable anonymous type so will error. + // Instead, serialize the type's symbol, but with the current symbol's name, rather than the anonymous one. + if (!context.remappedSymbolReferences) { + context.remappedSymbolReferences = new Map(); + } + context.remappedSymbolReferences.set(getSymbolId(type.symbol), symbol); // save name remapping as local name for target symbol + serializeSymbolWorker(type.symbol, isPrivate, propertyAsAlias, escapedSymbolName); + context.remappedSymbolReferences.delete(getSymbolId(type.symbol)); + } + else if (!(symbol.flags & SymbolFlags.Function) && isTypeRepresentableAsFunctionNamespaceMerge(type, symbol)) { + // If the type looks like a function declaration + ns could represent it, and it's type is sourced locally, rewrite it into a function declaration + ns + serializeAsFunctionNamespaceMerge(type, symbol, localName, modifierFlags); + } + else { + // A Class + Property merge is made for a `module.exports.Member = class {}`, and it doesn't serialize well as either a class _or_ a property symbol - in fact, _it behaves like an alias!_ + // `var` is `FunctionScopedVariable`, `const` and `let` are `BlockScopedVariable`, and `module.exports.thing =` is `Property` + const flags = !(symbol.flags & SymbolFlags.BlockScopedVariable) + ? symbol.parent?.valueDeclaration && isSourceFile(symbol.parent?.valueDeclaration) + ? NodeFlags.Const // exports are immutable in es6, which is what we emulate and check; so it's safe to mark all exports as `const` (there's no difference to consumers, but it allows unique symbol type declarations) + : undefined + : isConstantVariable(symbol) + ? NodeFlags.Const + : NodeFlags.Let; + const name = (needsPostExportDefault || !(symbol.flags & SymbolFlags.Property)) ? localName : getUnusedName(localName, symbol); + let textRange: Node | undefined = symbol.declarations && find(symbol.declarations, d => isVariableDeclaration(d)); + if (textRange && isVariableDeclarationList(textRange.parent) && textRange.parent.declarations.length === 1) { + textRange = textRange.parent.parent; + } + const propertyAccessRequire = symbol.declarations?.find(isPropertyAccessExpression); + if ( + propertyAccessRequire && isBinaryExpression(propertyAccessRequire.parent) && isIdentifier(propertyAccessRequire.parent.right) + && type.symbol?.valueDeclaration && isSourceFile(type.symbol.valueDeclaration) + ) { + const alias = localName === propertyAccessRequire.parent.right.escapedText ? undefined : propertyAccessRequire.parent.right; + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, alias, localName)]), + ), + ModifierFlags.None, + ); + context.tracker.trackSymbol(type.symbol, context.enclosingDeclaration, SymbolFlags.Value); + } + else { + const statement = setTextRange( + context, + factory.createVariableStatement( + /*modifiers*/ undefined, + factory.createVariableDeclarationList([ + factory.createVariableDeclaration(name, /*exclamationToken*/ undefined, serializeTypeForDeclaration(context, /*declaration*/ undefined, type, symbol)), + ], flags), + ), + textRange, + ); + addResult(statement, name !== localName ? modifierFlags & ~ModifierFlags.Export : modifierFlags); + if (name !== localName && !isPrivate) { + // We rename the variable declaration we generate for Property symbols since they may have a name which + // conflicts with a local declaration. For example, given input: + // ``` + // function g() {} + // module.exports.g = g + // ``` + // In such a situation, we have a local variable named `g`, and a separate exported variable named `g`. + // Naively, we would emit + // ``` + // function g() {} + // export const g: typeof g; + // ``` + // That's obviously incorrect - the `g` in the type annotation needs to refer to the local `g`, but + // the export declaration shadows it. + // To work around that, we instead write + // ``` + // function g() {} + // const g_1: typeof g; + // export { g_1 as g }; + // ``` + // To create an export named `g` that does _not_ shadow the local `g` + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, name, localName)]), + ), + ModifierFlags.None, + ); + needsExportDeclaration = false; + needsPostExportDefault = false; + } + } + } + } + } + if (symbol.flags & SymbolFlags.Enum) { + serializeEnum(symbol, symbolName, modifierFlags); + } + if (symbol.flags & SymbolFlags.Class) { + if ( + symbol.flags & SymbolFlags.Property + && symbol.valueDeclaration + && isBinaryExpression(symbol.valueDeclaration.parent) + && isClassExpression(symbol.valueDeclaration.parent.right) + ) { + // Looks like a `module.exports.Sub = class {}` - if we serialize `symbol` as a class, the result will have no members, + // since the classiness is actually from the target of the effective alias the symbol is. yes. A BlockScopedVariable|Class|Property + // _really_ acts like an Alias, and none of a BlockScopedVariable, Class, or Property. This is the travesty of JS binding today. + serializeAsAlias(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + else { + serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + } + if ((symbol.flags & (SymbolFlags.ValueModule | SymbolFlags.NamespaceModule) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) { + serializeModule(symbol, symbolName, modifierFlags); + } + // The class meaning serialization should handle serializing all interface members + if (symbol.flags & SymbolFlags.Interface && !(symbol.flags & SymbolFlags.Class)) { + serializeInterface(symbol, symbolName, modifierFlags); + } + if (symbol.flags & SymbolFlags.Alias) { + serializeAsAlias(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + if (symbol.flags & SymbolFlags.Property && symbol.escapedName === InternalSymbolName.ExportEquals) { + serializeMaybeAliasAssignment(symbol); + } + if (symbol.flags & SymbolFlags.ExportStar) { + // synthesize export * from "moduleReference" + // Straightforward - only one thing to do - make an export declaration + if (symbol.declarations) { + for (const node of symbol.declarations) { + const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!); + if (!resolvedModule) continue; + addResult(factory.createExportDeclaration(/*modifiers*/ undefined, /*isTypeOnly*/ (node as ExportDeclaration).isTypeOnly, /*exportClause*/ undefined, factory.createStringLiteral(getSpecifierForModuleSymbol(resolvedModule, context))), ModifierFlags.None); + } + } + } + if (needsPostExportDefault) { + addResult(factory.createExportAssignment(/*modifiers*/ undefined, /*isExportEquals*/ false, factory.createIdentifier(getInternalSymbolName(symbol, symbolName))), ModifierFlags.None); + } + else if (needsExportDeclaration) { + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, getInternalSymbolName(symbol, symbolName), symbolName)]), + ), + ModifierFlags.None, + ); + } + } + + function includePrivateSymbol(symbol: Symbol) { + if (some(symbol.declarations, isPartOfParameterDeclaration)) return; + Debug.assertIsDefined(deferredPrivatesStack[deferredPrivatesStack.length - 1]); + getUnusedName(unescapeLeadingUnderscores(symbol.escapedName), symbol); // Call to cache unique name for symbol + // Blanket moving (import) aliases into the root private context should work, since imports are not valid within namespaces + // (so they must have been in the root to begin with if they were real imports) cjs `require` aliases (an upcoming feature) + // will throw a wrench in this, since those may have been nested, but we'll need to synthesize them in the outer scope + // anyway, as that's the only place the import they translate to is valid. In such a case, we might need to use a unique name + // for the moved import; which hopefully the above `getUnusedName` call should produce. + const isExternalImportAlias = !!(symbol.flags & SymbolFlags.Alias) && !some(symbol.declarations, d => + !!findAncestor(d, isExportDeclaration) || + isNamespaceExport(d) || + (isImportEqualsDeclaration(d) && !isExternalModuleReference(d.moduleReference))); + deferredPrivatesStack[isExternalImportAlias ? 0 : (deferredPrivatesStack.length - 1)].set(getSymbolId(symbol), symbol); + } + + function isExportingScope(enclosingDeclaration: Node) { + return ((isSourceFile(enclosingDeclaration) && (isExternalOrCommonJsModule(enclosingDeclaration) || isJsonSourceFile(enclosingDeclaration))) || + (isAmbientModule(enclosingDeclaration) && !isGlobalScopeAugmentation(enclosingDeclaration))); + } + + // Prepends a `declare` and/or `export` modifier if the context requires it, and then adds `node` to `result` and returns `node` + function addResult(node: Statement, additionalModifierFlags: ModifierFlags) { + if (canHaveModifiers(node)) { + let newModifierFlags: ModifierFlags = ModifierFlags.None; + const enclosingDeclaration = context.enclosingDeclaration && + (isJSDocTypeAlias(context.enclosingDeclaration) ? getSourceFileOfNode(context.enclosingDeclaration) : context.enclosingDeclaration); + if ( + additionalModifierFlags & ModifierFlags.Export && + enclosingDeclaration && (isExportingScope(enclosingDeclaration) || isModuleDeclaration(enclosingDeclaration)) && + canHaveExportModifier(node) + ) { + // Classes, namespaces, variables, functions, interfaces, and types should all be `export`ed in a module context if not private + newModifierFlags |= ModifierFlags.Export; + } + if ( + addingDeclare && !(newModifierFlags & ModifierFlags.Export) && + (!enclosingDeclaration || !(enclosingDeclaration.flags & NodeFlags.Ambient)) && + (isEnumDeclaration(node) || isVariableStatement(node) || isFunctionDeclaration(node) || isClassDeclaration(node) || isModuleDeclaration(node)) + ) { + // Classes, namespaces, variables, enums, and functions all need `declare` modifiers to be valid in a declaration file top-level scope + newModifierFlags |= ModifierFlags.Ambient; + } + if ((additionalModifierFlags & ModifierFlags.Default) && (isClassDeclaration(node) || isInterfaceDeclaration(node) || isFunctionDeclaration(node))) { + newModifierFlags |= ModifierFlags.Default; + } + if (newModifierFlags) { + node = factory.replaceModifiers(node, newModifierFlags | getEffectiveModifierFlags(node)); + } + } + results.push(node); + } + + function serializeTypeAlias(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + const aliasType = getDeclaredTypeOfTypeAlias(symbol); + const typeParams = getSymbolLinks(symbol).typeParameters; + const typeParamDecls = map(typeParams, p => typeParameterToDeclaration(p, context)); + const jsdocAliasDecl = symbol.declarations?.find(isJSDocTypeAlias); + const commentText = getTextOfJSDocComment(jsdocAliasDecl ? jsdocAliasDecl.comment || jsdocAliasDecl.parent.comment : undefined); + const oldFlags = context.flags; + context.flags |= NodeBuilderFlags.InTypeAlias; + const oldEnclosingDecl = context.enclosingDeclaration; + context.enclosingDeclaration = jsdocAliasDecl; + const typeNode = jsdocAliasDecl && jsdocAliasDecl.typeExpression + && isJSDocTypeExpression(jsdocAliasDecl.typeExpression) + && tryReuseExistingNonParameterTypeNode(context, jsdocAliasDecl.typeExpression.type, aliasType, /*host*/ undefined) + || typeToTypeNodeHelper(aliasType, context); + addResult( + setSyntheticLeadingComments( + factory.createTypeAliasDeclaration(/*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, typeNode), + !commentText ? [] : [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }], + ), + modifierFlags, + ); + context.flags = oldFlags; + context.enclosingDeclaration = oldEnclosingDecl; + } + + function serializeInterface(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + const interfaceType = getDeclaredTypeOfClassOrInterface(symbol); + const localParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + const typeParamDecls = map(localParams, p => typeParameterToDeclaration(p, context)); + const baseTypes = getBaseTypes(interfaceType); + const baseType = length(baseTypes) ? getIntersectionType(baseTypes) : undefined; + const members = flatMap(getPropertiesOfType(interfaceType), p => serializePropertySymbolForInterface(p, baseType)); + const callSignatures = serializeSignatures(SignatureKind.Call, interfaceType, baseType, SyntaxKind.CallSignature) as CallSignatureDeclaration[]; + const constructSignatures = serializeSignatures(SignatureKind.Construct, interfaceType, baseType, SyntaxKind.ConstructSignature) as ConstructSignatureDeclaration[]; + const indexSignatures = serializeIndexSignatures(interfaceType, baseType); + + const heritageClauses = !length(baseTypes) ? undefined : [factory.createHeritageClause(SyntaxKind.ExtendsKeyword, mapDefined(baseTypes, b => trySerializeAsTypeReference(b, SymbolFlags.Value)))]; + addResult( + factory.createInterfaceDeclaration( + /*modifiers*/ undefined, + getInternalSymbolName(symbol, symbolName), + typeParamDecls, + heritageClauses, + [...indexSignatures, ...constructSignatures, ...callSignatures, ...members], + ), + modifierFlags, + ); + } + + function getNamespaceMembersForSerialization(symbol: Symbol) { + let exports = arrayFrom(getExportsOfSymbol(symbol).values()); + const merged = getMergedSymbol(symbol); + if (merged !== symbol) { + const membersSet = new Set(exports); + for (const exported of getExportsOfSymbol(merged).values()) { + if (!(getSymbolFlags(resolveSymbol(exported)) & SymbolFlags.Value)) { + membersSet.add(exported); + } + } + exports = arrayFrom(membersSet); + } + return filter(exports, m => isNamespaceMember(m) && isIdentifierText(m.escapedName as string, ScriptTarget.ESNext)); + } + + function isTypeOnlyNamespace(symbol: Symbol) { + return every(getNamespaceMembersForSerialization(symbol), m => !(getSymbolFlags(resolveSymbol(m)) & SymbolFlags.Value)); + } + + function serializeModule(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + const members = getNamespaceMembersForSerialization(symbol); + // Split NS members up by declaration - members whose parent symbol is the ns symbol vs those whose is not (but were added in later via merging) + const locationMap = arrayToMultiMap(members, m => m.parent && m.parent === symbol ? "real" : "merged"); + const realMembers = locationMap.get("real") || emptyArray; + const mergedMembers = locationMap.get("merged") || emptyArray; + // TODO: `suppressNewPrivateContext` is questionable -we need to simply be emitting privates in whatever scope they were declared in, rather + // than whatever scope we traverse to them in. That's a bit of a complex rewrite, since we're not _actually_ tracking privates at all in advance, + // so we don't even have placeholders to fill in. + if (length(realMembers)) { + const localName = getInternalSymbolName(symbol, symbolName); + serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (SymbolFlags.Function | SymbolFlags.Assignment))); + } + if (length(mergedMembers)) { + const containingFile = getSourceFileOfNode(context.enclosingDeclaration); + const localName = getInternalSymbolName(symbol, symbolName); + const nsBody = factory.createModuleBlock([factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(mapDefined(filter(mergedMembers, n => n.escapedName !== InternalSymbolName.ExportEquals), s => { + const name = unescapeLeadingUnderscores(s.escapedName); + const localName = getInternalSymbolName(s, name); + const aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s); + if (containingFile && (aliasDecl ? containingFile !== getSourceFileOfNode(aliasDecl) : !some(s.declarations, d => getSourceFileOfNode(d) === containingFile))) { + context.tracker?.reportNonlocalAugmentation?.(containingFile, symbol, s); + return undefined; + } + const target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true); + includePrivateSymbol(target || s); + const targetName = target ? getInternalSymbolName(target, unescapeLeadingUnderscores(target.escapedName)) : localName; + return factory.createExportSpecifier(/*isTypeOnly*/ false, name === targetName ? undefined : targetName, name); + })), + )]); + addResult( + factory.createModuleDeclaration( + /*modifiers*/ undefined, + factory.createIdentifier(localName), + nsBody, + NodeFlags.Namespace, + ), + ModifierFlags.None, + ); + } + } + + function serializeEnum(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + addResult( + factory.createEnumDeclaration( + factory.createModifiersFromModifierFlags(isConstEnumSymbol(symbol) ? ModifierFlags.Const : 0), + getInternalSymbolName(symbol, symbolName), + map(filter(getPropertiesOfType(getTypeOfSymbol(symbol)), p => !!(p.flags & SymbolFlags.EnumMember)), p => { + // TODO: Handle computed names + // I hate that to get the initialized value we need to walk back to the declarations here; but there's no + // other way to get the possible const value of an enum member that I'm aware of, as the value is cached + // _on the declaration_, not on the declaration's symbol... + const initializedValue = p.declarations && p.declarations[0] && isEnumMember(p.declarations[0]) ? getConstantValue(p.declarations[0]) : undefined; + return factory.createEnumMember( + unescapeLeadingUnderscores(p.escapedName), + initializedValue === undefined ? undefined : + typeof initializedValue === "string" ? factory.createStringLiteral(initializedValue) : + factory.createNumericLiteral(initializedValue), + ); + }), + ), + modifierFlags, + ); + } + + function serializeAsFunctionNamespaceMerge(type: Type, symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { + const signatures = getSignaturesOfType(type, SignatureKind.Call); + for (const sig of signatures) { + // Each overload becomes a separate function declaration, in order + const decl = signatureToSignatureDeclarationHelper(sig, SyntaxKind.FunctionDeclaration, context, { name: factory.createIdentifier(localName) }) as FunctionDeclaration; + addResult(setTextRange(context, decl, getSignatureTextRangeLocation(sig)), modifierFlags); + } + // Module symbol emit will take care of module-y members, provided it has exports + if (!(symbol.flags & (SymbolFlags.ValueModule | SymbolFlags.NamespaceModule) && !!symbol.exports && !!symbol.exports.size)) { + const props = filter(getPropertiesOfType(type), isNamespaceMember); + serializeAsNamespaceDeclaration(props, localName, modifierFlags, /*suppressNewPrivateContext*/ true); + } + } + + function getSignatureTextRangeLocation(signature: Signature) { + if (signature.declaration && signature.declaration.parent) { + if (isBinaryExpression(signature.declaration.parent) && getAssignmentDeclarationKind(signature.declaration.parent) === AssignmentDeclarationKind.Property) { + return signature.declaration.parent; + } + // for expressions assigned to `var`s, use the `var` as the text range + if (isVariableDeclaration(signature.declaration.parent) && signature.declaration.parent.parent) { + return signature.declaration.parent.parent; + } + } + return signature.declaration; + } + + function serializeAsNamespaceDeclaration(props: readonly Symbol[], localName: string, modifierFlags: ModifierFlags, suppressNewPrivateContext: boolean) { + if (length(props)) { + const localVsRemoteMap = arrayToMultiMap(props, p => !length(p.declarations) || some(p.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(context.enclosingDeclaration!)) ? "local" : "remote"); + const localProps = localVsRemoteMap.get("local") || emptyArray; + // handle remote props first - we need to make an `import` declaration that points at the module containing each remote + // prop in the outermost scope (TODO: a namespace within a namespace would need to be appropriately handled by this) + // Example: + // import Foo_1 = require("./exporter"); + // export namespace ns { + // import Foo = Foo_1.Foo; + // export { Foo }; + // export const c: number; + // } + // This is needed because in JS, statements like `const x = require("./f")` support both type and value lookup, even if they're + // normally just value lookup (so it functions kinda like an alias even when it's not an alias) + // _Usually_, we'll simply print the top-level as an alias instead of a `var` in such situations, however is is theoretically + // possible to encounter a situation where a type has members from both the current file and other files - in those situations, + // emit akin to the above would be needed. + + // Add a namespace + // Create namespace as non-synthetic so it is usable as an enclosing declaration + let fakespace = parseNodeFactory.createModuleDeclaration(/*modifiers*/ undefined, factory.createIdentifier(localName), factory.createModuleBlock([]), NodeFlags.Namespace); + setParent(fakespace, enclosingDeclaration as SourceFile | NamespaceDeclaration); + fakespace.locals = createSymbolTable(props); + fakespace.symbol = props[0].parent!; + + const oldResults = results; + results = []; + const oldAddingDeclare = addingDeclare; + addingDeclare = false; + const subcontext = { ...context, enclosingDeclaration: fakespace }; + const oldContext = context; + context = subcontext; + // TODO: implement handling for the localVsRemoteMap.get("remote") - should be difficult to trigger (see comment above), as only interesting cross-file js merges should make this possible + visitSymbolTable(createSymbolTable(localProps), suppressNewPrivateContext, /*propertyAsAlias*/ true); + context = oldContext; + addingDeclare = oldAddingDeclare; + const declarations = results; + results = oldResults; + // replace namespace with synthetic version + const defaultReplaced = map(declarations, d => + isExportAssignment(d) && !d.isExportEquals && isIdentifier(d.expression) ? factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, d.expression, factory.createIdentifier(InternalSymbolName.Default))]), + ) : d); + const exportModifierStripped = every(defaultReplaced, d => hasSyntacticModifier(d, ModifierFlags.Export)) ? map(defaultReplaced as Extract[], removeExportModifier) : defaultReplaced; + fakespace = factory.updateModuleDeclaration( + fakespace, + fakespace.modifiers, + fakespace.name, + factory.createModuleBlock(exportModifierStripped), + ); + addResult(fakespace, modifierFlags); // namespaces can never be default exported + } + } + + function isNamespaceMember(p: Symbol) { + return !!(p.flags & (SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias)) || + !(p.flags & SymbolFlags.Prototype || p.escapedName === "prototype" || p.valueDeclaration && isStatic(p.valueDeclaration) && isClassLike(p.valueDeclaration.parent)); + } + + function sanitizeJSDocImplements(clauses: readonly ExpressionWithTypeArguments[]): ExpressionWithTypeArguments[] | undefined { + const result = mapDefined(clauses, e => { + const oldEnclosing = context.enclosingDeclaration; + context.enclosingDeclaration = e; + let expr = e.expression; + if (isEntityNameExpression(expr)) { + if (isIdentifier(expr) && idText(expr) === "") { + return cleanup(/*result*/ undefined); // Empty heritage clause, should be an error, but prefer emitting no heritage clauses to reemitting the empty one + } + let introducesError: boolean; + ({ introducesError, node: expr } = trackExistingEntityName(expr, context)); + if (introducesError) { + return cleanup(/*result*/ undefined); + } + } + return cleanup(factory.createExpressionWithTypeArguments( + expr, + map(e.typeArguments, a => + tryReuseExistingNonParameterTypeNode(context, a, getTypeFromTypeNode(context, a)) + || typeToTypeNodeHelper(getTypeFromTypeNode(context, a), context)), + )); + + function cleanup(result: T): T { + context.enclosingDeclaration = oldEnclosing; + return result; + } + }); + if (result.length === clauses.length) { + return result; + } + return undefined; + } + + function serializeAsClass(symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { + const originalDecl = symbol.declarations?.find(isClassLike); + const oldEnclosing = context.enclosingDeclaration; + context.enclosingDeclaration = originalDecl || oldEnclosing; + const localParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + const typeParamDecls = map(localParams, p => typeParameterToDeclaration(p, context)); + const classType = getTypeWithThisArgument(getDeclaredTypeOfClassOrInterface(symbol)) as InterfaceType; + const baseTypes = getBaseTypes(classType); + const originalImplements = originalDecl && getEffectiveImplementsTypeNodes(originalDecl); + const implementsExpressions = originalImplements && sanitizeJSDocImplements(originalImplements) + || mapDefined(getImplementsTypes(classType), serializeImplementedType); + const staticType = getTypeOfSymbol(symbol); + const isClass = !!staticType.symbol?.valueDeclaration && isClassLike(staticType.symbol.valueDeclaration); + const staticBaseType = isClass + ? getBaseConstructorTypeOfClass(staticType as InterfaceType) + : anyType; + const heritageClauses = [ + ...!length(baseTypes) ? [] : [factory.createHeritageClause(SyntaxKind.ExtendsKeyword, map(baseTypes, b => serializeBaseType(b, staticBaseType, localName)))], + ...!length(implementsExpressions) ? [] : [factory.createHeritageClause(SyntaxKind.ImplementsKeyword, implementsExpressions)], + ]; + const symbolProps = getNonInheritedProperties(classType, baseTypes, getPropertiesOfType(classType)); + const publicSymbolProps = filter(symbolProps, s => { + // `valueDeclaration` could be undefined if inherited from + // a union/intersection base type, but inherited properties + // don't matter here. + const valueDecl = s.valueDeclaration; + return !!valueDecl && !(isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name)); + }); + const hasPrivateIdentifier = some(symbolProps, s => { + // `valueDeclaration` could be undefined if inherited from + // a union/intersection base type, but inherited properties + // don't matter here. + const valueDecl = s.valueDeclaration; + return !!valueDecl && isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name); + }); + // Boil down all private properties into a single one. + const privateProperties = hasPrivateIdentifier ? + [factory.createPropertyDeclaration( + /*modifiers*/ undefined, + factory.createPrivateIdentifier("#private"), + /*questionOrExclamationToken*/ undefined, + /*type*/ undefined, + /*initializer*/ undefined, + )] : + emptyArray; + const publicProperties = flatMap(publicSymbolProps, p => serializePropertySymbolForClass(p, /*isStatic*/ false, baseTypes[0])); + // Consider static members empty if symbol also has function or module meaning - function namespacey emit will handle statics + const staticMembers = flatMap( + filter(getPropertiesOfType(staticType), p => !(p.flags & SymbolFlags.Prototype) && p.escapedName !== "prototype" && !isNamespaceMember(p)), + p => serializePropertySymbolForClass(p, /*isStatic*/ true, staticBaseType), + ); + // When we encounter an `X.prototype.y` assignment in a JS file, we bind `X` as a class regardless as to whether + // the value is ever initialized with a class or function-like value. For cases where `X` could never be + // created via `new`, we will inject a `private constructor()` declaration to indicate it is not createable. + const isNonConstructableClassLikeInJsFile = !isClass && + !!symbol.valueDeclaration && + isInJSFile(symbol.valueDeclaration) && + !some(getSignaturesOfType(staticType, SignatureKind.Construct)); + const constructors = isNonConstructableClassLikeInJsFile ? + [factory.createConstructorDeclaration(factory.createModifiersFromModifierFlags(ModifierFlags.Private), [], /*body*/ undefined)] : + serializeSignatures(SignatureKind.Construct, staticType, staticBaseType, SyntaxKind.Constructor) as ConstructorDeclaration[]; + const indexSignatures = serializeIndexSignatures(classType, baseTypes[0]); + context.enclosingDeclaration = oldEnclosing; + addResult( + setTextRange( + context, + factory.createClassDeclaration( + /*modifiers*/ undefined, + localName, + typeParamDecls, + heritageClauses, + [...indexSignatures, ...staticMembers, ...constructors, ...publicProperties, ...privateProperties], + ), + symbol.declarations && filter(symbol.declarations, d => isClassDeclaration(d) || isClassExpression(d))[0], + ), + modifierFlags, + ); + } + + function getSomeTargetNameFromDeclarations(declarations: Declaration[] | undefined) { + return firstDefined(declarations, d => { + if (isImportSpecifier(d) || isExportSpecifier(d)) { + return moduleExportNameTextUnescaped(d.propertyName || d.name); + } + if (isBinaryExpression(d) || isExportAssignment(d)) { + const expression = isExportAssignment(d) ? d.expression : d.right; + if (isPropertyAccessExpression(expression)) { + return idText(expression.name); + } + } + if (isAliasSymbolDeclaration(d)) { + // This is... heuristic, at best. But it's probably better than always printing the name of the shorthand ambient module. + const name = getNameOfDeclaration(d); + if (name && isIdentifier(name)) { + return idText(name); + } + } + return undefined; + }); + } + + function serializeAsAlias(symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { + // synthesize an alias, eg `export { symbolName as Name }` + // need to mark the alias `symbol` points at + // as something we need to serialize as a private declaration as well + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + const target = getMergedSymbol(getTargetOfAliasDeclaration(node, /*dontRecursivelyResolve*/ true)); + if (!target) { + return; + } + // If `target` refers to a shorthand module symbol, the name we're trying to pull out isn;t recoverable from the target symbol + // In such a scenario, we must fall back to looking for an alias declaration on `symbol` and pulling the target name from that + let verbatimTargetName = isShorthandAmbientModuleSymbol(target) && getSomeTargetNameFromDeclarations(symbol.declarations) || unescapeLeadingUnderscores(target.escapedName); + if (verbatimTargetName === InternalSymbolName.ExportEquals && allowSyntheticDefaultImports) { + // target refers to an `export=` symbol that was hoisted into a synthetic default - rename here to match + verbatimTargetName = InternalSymbolName.Default; + } + const targetName = getInternalSymbolName(target, verbatimTargetName); + includePrivateSymbol(target); // the target may be within the same scope - attempt to serialize it first + switch (node.kind) { + case SyntaxKind.BindingElement: + if (node.parent?.parent?.kind === SyntaxKind.VariableDeclaration) { + // const { SomeClass } = require('./lib'); + const specifier = getSpecifierForModuleSymbol(target.parent || target, context); // './lib' + const { propertyName } = node as BindingElement; + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause( + /*isTypeOnly*/ false, + /*name*/ undefined, + factory.createNamedImports([factory.createImportSpecifier( + /*isTypeOnly*/ false, + propertyName && isIdentifier(propertyName) ? factory.createIdentifier(idText(propertyName)) : undefined, + factory.createIdentifier(localName), + )]), + ), + factory.createStringLiteral(specifier), + /*attributes*/ undefined, + ), + ModifierFlags.None, + ); + break; + } + // We don't know how to serialize this (nested?) binding element + Debug.failBadSyntaxKind(node.parent?.parent || node, "Unhandled binding element grandparent kind in declaration serialization"); + break; + case SyntaxKind.ShorthandPropertyAssignment: + if (node.parent?.parent?.kind === SyntaxKind.BinaryExpression) { + // module.exports = { SomeClass } + serializeExportSpecifier( + unescapeLeadingUnderscores(symbol.escapedName), + targetName, + ); + } + break; + case SyntaxKind.VariableDeclaration: + // commonjs require: const x = require('y') + if (isPropertyAccessExpression((node as VariableDeclaration).initializer!)) { + // const x = require('y').z + const initializer = (node as VariableDeclaration).initializer! as PropertyAccessExpression; // require('y').z + const uniqueName = factory.createUniqueName(localName); // _x + const specifier = getSpecifierForModuleSymbol(target.parent || target, context); // 'y' + // import _x = require('y'); + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + uniqueName, + factory.createExternalModuleReference(factory.createStringLiteral(specifier)), + ), + ModifierFlags.None, + ); + // import x = _x.z + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createIdentifier(localName), + factory.createQualifiedName(uniqueName, initializer.name as Identifier), + ), + modifierFlags, + ); + break; + } + // else fall through and treat commonjs require just like import= + case SyntaxKind.ImportEqualsDeclaration: + // This _specifically_ only exists to handle json declarations - where we make aliases, but since + // we emit no declarations for the json document, must not refer to it in the declarations + if (target.escapedName === InternalSymbolName.ExportEquals && some(target.declarations, d => isSourceFile(d) && isJsonSourceFile(d))) { + serializeMaybeAliasAssignment(symbol); + break; + } + // Could be a local `import localName = ns.member` or + // an external `import localName = require("whatever")` + const isLocalImport = !(target.flags & SymbolFlags.ValueModule) && !isVariableDeclaration(node); + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createIdentifier(localName), + isLocalImport + ? symbolToName(target, context, SymbolFlags.All, /*expectsIdentifier*/ false) + : factory.createExternalModuleReference(factory.createStringLiteral(getSpecifierForModuleSymbol(target, context))), + ), + isLocalImport ? modifierFlags : ModifierFlags.None, + ); + break; + case SyntaxKind.NamespaceExportDeclaration: + // export as namespace foo + // TODO: Not part of a file's local or export symbol tables + // Is bound into file.symbol.globalExports instead, which we don't currently traverse + addResult(factory.createNamespaceExportDeclaration(idText((node as NamespaceExportDeclaration).name)), ModifierFlags.None); + break; + case SyntaxKind.ImportClause: { + const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects + const specifier = context.bundled ? factory.createStringLiteral(generatedSpecifier) : (node as ImportClause).parent.moduleSpecifier; + const attributes = isImportDeclaration(node.parent) ? node.parent.attributes : undefined; + const isTypeOnly = isJSDocImportTag((node as ImportClause).parent); + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause(isTypeOnly, factory.createIdentifier(localName), /*namedBindings*/ undefined), + specifier, + attributes, + ), + ModifierFlags.None, + ); + break; + } + case SyntaxKind.NamespaceImport: { + const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects + const specifier = context.bundled ? factory.createStringLiteral(generatedSpecifier) : (node as NamespaceImport).parent.parent.moduleSpecifier; + const isTypeOnly = isJSDocImportTag((node as NamespaceImport).parent.parent); + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause(isTypeOnly, /*name*/ undefined, factory.createNamespaceImport(factory.createIdentifier(localName))), + specifier, + (node as ImportClause).parent.attributes, + ), + ModifierFlags.None, + ); + break; + } + case SyntaxKind.NamespaceExport: + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamespaceExport(factory.createIdentifier(localName)), + factory.createStringLiteral(getSpecifierForModuleSymbol(target, context)), + ), + ModifierFlags.None, + ); + break; + case SyntaxKind.ImportSpecifier: { + const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects + const specifier = context.bundled ? factory.createStringLiteral(generatedSpecifier) : (node as ImportSpecifier).parent.parent.parent.moduleSpecifier; + const isTypeOnly = isJSDocImportTag((node as ImportSpecifier).parent.parent.parent); + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause( + isTypeOnly, + /*name*/ undefined, + factory.createNamedImports([ + factory.createImportSpecifier( + /*isTypeOnly*/ false, + localName !== verbatimTargetName ? factory.createIdentifier(verbatimTargetName) : undefined, + factory.createIdentifier(localName), + ), + ]), + ), + specifier, + (node as ImportSpecifier).parent.parent.parent.attributes, + ), + ModifierFlags.None, + ); + break; + } + case SyntaxKind.ExportSpecifier: + // does not use localName because the symbol name in this case refers to the name in the exports table, + // which we must exactly preserve + const specifier = (node.parent.parent as ExportDeclaration).moduleSpecifier; + if (specifier) { + const propertyName = (node as ExportSpecifier).propertyName; + if (propertyName && moduleExportNameIsDefault(propertyName)) { + verbatimTargetName = InternalSymbolName.Default; + } + } + // targetName is only used when the target is local, as otherwise the target is an alias that points at + // another file + serializeExportSpecifier( + unescapeLeadingUnderscores(symbol.escapedName), + specifier ? verbatimTargetName : targetName, + specifier && isStringLiteralLike(specifier) ? factory.createStringLiteral(specifier.text) : undefined, + ); + break; + case SyntaxKind.ExportAssignment: + serializeMaybeAliasAssignment(symbol); + break; + case SyntaxKind.BinaryExpression: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + // Could be best encoded as though an export specifier or as though an export assignment + // If name is default or export=, do an export assignment + // Otherwise do an export specifier + if (symbol.escapedName === InternalSymbolName.Default || symbol.escapedName === InternalSymbolName.ExportEquals) { + serializeMaybeAliasAssignment(symbol); + } + else { + serializeExportSpecifier(localName, targetName); + } + break; + default: + return Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!"); + } + } + + function serializeExportSpecifier(localName: string, targetName: string, specifier?: Expression) { + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, localName !== targetName ? targetName : undefined, localName)]), + specifier, + ), + ModifierFlags.None, + ); + } + + /** + * Returns `true` if an export assignment or declaration was produced for the symbol + */ + function serializeMaybeAliasAssignment(symbol: Symbol): boolean { + if (symbol.flags & SymbolFlags.Prototype) { + return false; + } + const name = unescapeLeadingUnderscores(symbol.escapedName); + const isExportEquals = name === InternalSymbolName.ExportEquals; + const isDefault = name === InternalSymbolName.Default; + const isExportAssignmentCompatibleSymbolName = isExportEquals || isDefault; + // synthesize export = ref + // ref should refer to either be a locally scoped symbol which we need to emit, or + // a reference to another namespace/module which we may need to emit an `import` statement for + const aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol); + // serialize what the alias points to, preserve the declaration's initializer + const target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true); + // If the target resolves and resolves to a thing defined in this file, emit as an alias, otherwise emit as a const + if (target && length(target.declarations) && some(target.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(enclosingDeclaration))) { + // In case `target` refers to a namespace member, look at the declaration and serialize the leftmost symbol in it + // eg, `namespace A { export class B {} }; exports = A.B;` + // Technically, this is all that's required in the case where the assignment is an entity name expression + const expr = aliasDecl && ((isExportAssignment(aliasDecl) || isBinaryExpression(aliasDecl)) ? getExportAssignmentExpression(aliasDecl) : getPropertyAssignmentAliasLikeExpression(aliasDecl as ShorthandPropertyAssignment | PropertyAssignment | PropertyAccessExpression)); + const first = expr && isEntityNameExpression(expr) ? getFirstNonModuleExportsIdentifier(expr) : undefined; + const referenced = first && resolveEntityName(first, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, enclosingDeclaration); + if (referenced || target) { + includePrivateSymbol(referenced || target); + } + + // We disable the context's symbol tracker for the duration of this name serialization + // as, by virtue of being here, the name is required to print something, and we don't want to + // issue a visibility error on it. Only anonymous classes that an alias points at _would_ issue + // a visibility error here (as they're not visible within any scope), but we want to hoist them + // into the containing scope anyway, so we want to skip the visibility checks. + const prevDisableTrackSymbol = context.tracker.disableTrackSymbol; + context.tracker.disableTrackSymbol = true; + if (isExportAssignmentCompatibleSymbolName) { + results.push(factory.createExportAssignment( + /*modifiers*/ undefined, + isExportEquals, + symbolToExpression(target, context, SymbolFlags.All), + )); + } + else { + if (first === expr && first) { + // serialize as `export {target as name}` + serializeExportSpecifier(name, idText(first)); + } + else if (expr && isClassExpression(expr)) { + serializeExportSpecifier(name, getInternalSymbolName(target, symbolName(target))); + } + else { + // serialize as `import _Ref = t.arg.et; export { _Ref as name }` + const varName = getUnusedName(name, symbol); + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createIdentifier(varName), + symbolToName(target, context, SymbolFlags.All, /*expectsIdentifier*/ false), + ), + ModifierFlags.None, + ); + serializeExportSpecifier(name, varName); + } + } + context.tracker.disableTrackSymbol = prevDisableTrackSymbol; + return true; + } + else { + // serialize as an anonymous property declaration + const varName = getUnusedName(name, symbol); + // We have to use `getWidenedType` here since the object within a json file is unwidened within the file + // (Unwidened types can only exist in expression contexts and should never be serialized) + const typeToSerialize = getWidenedType(getTypeOfSymbol(getMergedSymbol(symbol))); + if (isTypeRepresentableAsFunctionNamespaceMerge(typeToSerialize, symbol)) { + // If there are no index signatures and `typeToSerialize` is an object type, emit as a namespace instead of a const + serializeAsFunctionNamespaceMerge(typeToSerialize, symbol, varName, isExportAssignmentCompatibleSymbolName ? ModifierFlags.None : ModifierFlags.Export); + } + else { + const flags = context.enclosingDeclaration?.kind === SyntaxKind.ModuleDeclaration && (!(symbol.flags & SymbolFlags.Accessor) || symbol.flags & SymbolFlags.SetAccessor) ? NodeFlags.Let : NodeFlags.Const; + const statement = factory.createVariableStatement( + /*modifiers*/ undefined, + factory.createVariableDeclarationList([ + factory.createVariableDeclaration(varName, /*exclamationToken*/ undefined, serializeTypeForDeclaration(context, /*declaration*/ undefined, typeToSerialize, symbol)), + ], flags), + ); + // Inlined JSON types exported with [module.]exports= will already emit an export=, so should use `declare`. + // Otherwise, the type itself should be exported. + addResult( + statement, + target && target.flags & SymbolFlags.Property && target.escapedName === InternalSymbolName.ExportEquals ? ModifierFlags.Ambient + : name === varName ? ModifierFlags.Export + : ModifierFlags.None, + ); + } + if (isExportAssignmentCompatibleSymbolName) { + results.push(factory.createExportAssignment( + /*modifiers*/ undefined, + isExportEquals, + factory.createIdentifier(varName), + )); + return true; + } + else if (name !== varName) { + serializeExportSpecifier(name, varName); + return true; + } + return false; + } + } + + function isTypeRepresentableAsFunctionNamespaceMerge(typeToSerialize: Type, hostSymbol: Symbol) { + // Only object types which are not constructable, or indexable, whose members all come from the + // context source file, and whose property names are all valid identifiers and not late-bound, _and_ + // whose input is not type annotated (if the input symbol has an annotation we can reuse, we should prefer it) + const ctxSrc = getSourceFileOfNode(context.enclosingDeclaration); + return getObjectFlags(typeToSerialize) & (ObjectFlags.Anonymous | ObjectFlags.Mapped) && + !some(typeToSerialize.symbol?.declarations, isTypeNode) && // If the type comes straight from a type node, we shouldn't try to break it up + !length(getIndexInfosOfType(typeToSerialize)) && + !isClassInstanceSide(typeToSerialize) && // While a class instance is potentially representable as a NS, prefer printing a reference to the instance type and serializing the class + !!(length(filter(getPropertiesOfType(typeToSerialize), isNamespaceMember)) || length(getSignaturesOfType(typeToSerialize, SignatureKind.Call))) && + !length(getSignaturesOfType(typeToSerialize, SignatureKind.Construct)) && // TODO: could probably serialize as function + ns + class, now that that's OK + !getDeclarationWithTypeAnnotation(hostSymbol, enclosingDeclaration) && + !(typeToSerialize.symbol && some(typeToSerialize.symbol.declarations, d => getSourceFileOfNode(d) !== ctxSrc)) && + !some(getPropertiesOfType(typeToSerialize), p => isLateBoundName(p.escapedName)) && + !some(getPropertiesOfType(typeToSerialize), p => some(p.declarations, d => getSourceFileOfNode(d) !== ctxSrc)) && + every(getPropertiesOfType(typeToSerialize), p => { + if (!isIdentifierText(symbolName(p), languageVersion)) { + return false; + } + if (!(p.flags & SymbolFlags.Accessor)) { + return true; + } + return getNonMissingTypeOfSymbol(p) === getWriteTypeOfSymbol(p); + }); + } + + function makeSerializePropertySymbol( + createProperty: ( + modifiers: readonly Modifier[] | undefined, + name: string | PropertyName, + questionOrExclamationToken: QuestionToken | undefined, + type: TypeNode | undefined, + initializer: Expression | undefined, + ) => T, + methodKind: SignatureDeclaration["kind"], + useAccessors: true, + ): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => T | AccessorDeclaration | (T | AccessorDeclaration)[]; + function makeSerializePropertySymbol( + createProperty: ( + modifiers: readonly Modifier[] | undefined, + name: string | PropertyName, + questionOrExclamationToken: QuestionToken | undefined, + type: TypeNode | undefined, + initializer: Expression | undefined, + ) => T, + methodKind: SignatureDeclaration["kind"], + useAccessors: false, + ): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => T | T[]; + function makeSerializePropertySymbol( + createProperty: ( + modifiers: readonly Modifier[] | undefined, + name: string | PropertyName, + questionOrExclamationToken: QuestionToken | undefined, + type: TypeNode | undefined, + initializer: Expression | undefined, + ) => T, + methodKind: SignatureDeclaration["kind"], + useAccessors: boolean, + ): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => T | AccessorDeclaration | (T | AccessorDeclaration)[] { + return function serializePropertySymbol(p: Symbol, isStatic: boolean, baseType: Type | undefined): T | AccessorDeclaration | (T | AccessorDeclaration)[] { + const modifierFlags = getDeclarationModifierFlagsFromSymbol(p); + const isPrivate = !!(modifierFlags & ModifierFlags.Private); + if (isStatic && (p.flags & (SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias))) { + // Only value-only-meaning symbols can be correctly encoded as class statics, type/namespace/alias meaning symbols + // need to be merged namespace members + return []; + } + if ( + p.flags & SymbolFlags.Prototype || p.escapedName === "constructor" || + (baseType && getPropertyOfType(baseType, p.escapedName) + && isReadonlySymbol(getPropertyOfType(baseType, p.escapedName)!) === isReadonlySymbol(p) + && (p.flags & SymbolFlags.Optional) === (getPropertyOfType(baseType, p.escapedName)!.flags & SymbolFlags.Optional) + && isTypeIdenticalTo(getTypeOfSymbol(p), getTypeOfPropertyOfType(baseType, p.escapedName)!)) + ) { + return []; + } + const flag = (modifierFlags & ~ModifierFlags.Async) | (isStatic ? ModifierFlags.Static : 0); + const name = getPropertyNameNodeForSymbol(p, context); + const firstPropertyLikeDecl = p.declarations?.find(or(isPropertyDeclaration, isAccessor, isVariableDeclaration, isPropertySignature, isBinaryExpression, isPropertyAccessExpression)); + if (p.flags & SymbolFlags.Accessor && useAccessors) { + const result: AccessorDeclaration[] = []; + if (p.flags & SymbolFlags.SetAccessor) { + const setter = p.declarations && forEach(p.declarations, d => { + if (d.kind === SyntaxKind.SetAccessor) { + return d as SetAccessorDeclaration; + } + if (isCallExpression(d) && isBindableObjectDefinePropertyCall(d)) { + return forEach(d.arguments[2].properties, propDecl => { + const id = getNameOfDeclaration(propDecl); + if (!!id && isIdentifier(id) && idText(id) === "set") { + return propDecl; + } + }); + } + }); + + Debug.assert(!!setter); + const paramSymbol = isFunctionLikeDeclaration(setter) ? getSignatureFromDeclaration(setter).parameters[0] : undefined; + + result.push(setTextRange( + context, + factory.createSetAccessorDeclaration( + factory.createModifiersFromModifierFlags(flag), + name, + [factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + paramSymbol ? parameterToParameterDeclarationName(paramSymbol, getEffectiveParameterDeclaration(paramSymbol), context) : "value", + /*questionToken*/ undefined, + isPrivate ? undefined : serializeTypeForDeclaration(context, /*declaration*/ undefined, getWriteTypeOfSymbol(p), p), + )], + /*body*/ undefined, + ), + p.declarations?.find(isSetAccessor) || firstPropertyLikeDecl, + )); + } + if (p.flags & SymbolFlags.GetAccessor) { + const isPrivate = modifierFlags & ModifierFlags.Private; + result.push(setTextRange( + context, + factory.createGetAccessorDeclaration( + factory.createModifiersFromModifierFlags(flag), + name, + [], + isPrivate ? undefined : serializeTypeForDeclaration(context, /*declaration*/ undefined, getTypeOfSymbol(p), p), + /*body*/ undefined, + ), + p.declarations?.find(isGetAccessor) || firstPropertyLikeDecl, + )); + } + return result; + } + // This is an else/if as accessors and properties can't merge in TS, but might in JS + // If this happens, we assume the accessor takes priority, as it imposes more constraints + else if (p.flags & (SymbolFlags.Property | SymbolFlags.Variable | SymbolFlags.Accessor)) { + return setTextRange( + context, + createProperty( + factory.createModifiersFromModifierFlags((isReadonlySymbol(p) ? ModifierFlags.Readonly : 0) | flag), + name, + p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + isPrivate ? undefined : serializeTypeForDeclaration(context, /*declaration*/ undefined, getWriteTypeOfSymbol(p), p), + // TODO: https://github.com/microsoft/TypeScript/pull/32372#discussion_r328386357 + // interface members can't have initializers, however class members _can_ + /*initializer*/ undefined, + ), + p.declarations?.find(or(isPropertyDeclaration, isVariableDeclaration)) || firstPropertyLikeDecl, + ); + } + if (p.flags & (SymbolFlags.Method | SymbolFlags.Function)) { + const type = getTypeOfSymbol(p); + const signatures = getSignaturesOfType(type, SignatureKind.Call); + if (flag & ModifierFlags.Private) { + return setTextRange( + context, + createProperty( + factory.createModifiersFromModifierFlags((isReadonlySymbol(p) ? ModifierFlags.Readonly : 0) | flag), + name, + p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + /*type*/ undefined, + /*initializer*/ undefined, + ), + p.declarations?.find(isFunctionLikeDeclaration) || signatures[0] && signatures[0].declaration || p.declarations && p.declarations[0], + ); + } + + const results = []; + for (const sig of signatures) { + // Each overload becomes a separate method declaration, in order + const decl = signatureToSignatureDeclarationHelper( + sig, + methodKind, + context, + { + name, + questionToken: p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + modifiers: flag ? factory.createModifiersFromModifierFlags(flag) : undefined, + }, + ); + const location = sig.declaration && isPrototypePropertyAssignment(sig.declaration.parent) ? sig.declaration.parent : sig.declaration; + results.push(setTextRange(context, decl, location)); + } + return results as unknown as T[]; + } + // The `Constructor`'s symbol isn't in the class's properties lists, obviously, since it's a signature on the static + return Debug.fail(`Unhandled class member kind! ${(p as any).__debugFlags || p.flags}`); + }; + } + + function serializePropertySymbolForInterface(p: Symbol, baseType: Type | undefined) { + return serializePropertySymbolForInterfaceWorker(p, /*isStatic*/ false, baseType); + } + + function serializeSignatures(kind: SignatureKind, input: Type, baseType: Type | undefined, outputKind: SignatureDeclaration["kind"]) { + const signatures = getSignaturesOfType(input, kind); + if (kind === SignatureKind.Construct) { + if (!baseType && every(signatures, s => length(s.parameters) === 0)) { + return []; // No base type, every constructor is empty - elide the extraneous `constructor()` + } + if (baseType) { + // If there is a base type, if every signature in the class is identical to a signature in the baseType, elide all the declarations + const baseSigs = getSignaturesOfType(baseType, SignatureKind.Construct); + if (!length(baseSigs) && every(signatures, s => length(s.parameters) === 0)) { + return []; // Base had no explicit signatures, if all our signatures are also implicit, return an empty list + } + if (baseSigs.length === signatures.length) { + let failed = false; + for (let i = 0; i < baseSigs.length; i++) { + if (!compareSignaturesIdentical(signatures[i], baseSigs[i], /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true, compareTypesIdentical)) { + failed = true; + break; + } + } + if (!failed) { + return []; // Every signature was identical - elide constructor list as it is inherited + } + } + } + let privateProtected: ModifierFlags = 0; + for (const s of signatures) { + if (s.declaration) { + privateProtected |= getSelectedEffectiveModifierFlags(s.declaration, ModifierFlags.Private | ModifierFlags.Protected); + } + } + if (privateProtected) { + return [setTextRange( + context, + factory.createConstructorDeclaration( + factory.createModifiersFromModifierFlags(privateProtected), + /*parameters*/ [], + /*body*/ undefined, + ), + signatures[0].declaration, + )]; + } + } + + const results = []; + for (const sig of signatures) { + // Each overload becomes a separate constructor declaration, in order + const decl = signatureToSignatureDeclarationHelper(sig, outputKind, context); + results.push(setTextRange(context, decl, sig.declaration)); + } + return results; + } + + function serializeIndexSignatures(input: Type, baseType: Type | undefined) { + const results: IndexSignatureDeclaration[] = []; + for (const info of getIndexInfosOfType(input)) { + if (baseType) { + const baseInfo = getIndexInfoOfType(baseType, info.keyType); + if (baseInfo) { + if (isTypeIdenticalTo(info.type, baseInfo.type)) { + continue; // elide identical index signatures + } + } + } + results.push(indexInfoToIndexSignatureDeclarationHelper(info, context, /*typeNode*/ undefined)); + } + return results; + } + + function serializeBaseType(t: Type, staticType: Type, rootName: string) { + const ref = trySerializeAsTypeReference(t, SymbolFlags.Value); + if (ref) { + return ref; + } + const tempName = getUnusedName(`${rootName}_base`); + const statement = factory.createVariableStatement( + /*modifiers*/ undefined, + factory.createVariableDeclarationList([ + factory.createVariableDeclaration(tempName, /*exclamationToken*/ undefined, typeToTypeNodeHelper(staticType, context)), + ], NodeFlags.Const), + ); + addResult(statement, ModifierFlags.None); + return factory.createExpressionWithTypeArguments(factory.createIdentifier(tempName), /*typeArguments*/ undefined); + } + + function trySerializeAsTypeReference(t: Type, flags: SymbolFlags) { + let typeArgs: TypeNode[] | undefined; + let reference: Expression | undefined; + + // We don't use `isValueSymbolAccessible` below. since that considers alternative containers (like modules) + // which we can't write out in a syntactically valid way as an expression + if ((t as TypeReference).target && isSymbolAccessibleByFlags((t as TypeReference).target.symbol, enclosingDeclaration, flags)) { + typeArgs = map(getTypeArguments(t as TypeReference), t => typeToTypeNodeHelper(t, context)); + reference = symbolToExpression((t as TypeReference).target.symbol, context, SymbolFlags.Type); + } + else if (t.symbol && isSymbolAccessibleByFlags(t.symbol, enclosingDeclaration, flags)) { + reference = symbolToExpression(t.symbol, context, SymbolFlags.Type); + } + if (reference) { + return factory.createExpressionWithTypeArguments(reference, typeArgs); + } + } + + function serializeImplementedType(t: Type) { + const ref = trySerializeAsTypeReference(t, SymbolFlags.Type); + if (ref) { + return ref; + } + if (t.symbol) { + return factory.createExpressionWithTypeArguments(symbolToExpression(t.symbol, context, SymbolFlags.Type), /*typeArguments*/ undefined); + } + } + + function getUnusedName(input: string, symbol?: Symbol): string { + const id = symbol ? getSymbolId(symbol) : undefined; + if (id) { + if (context.remappedSymbolNames!.has(id)) { + return context.remappedSymbolNames!.get(id)!; + } + } + if (symbol) { + input = getNameCandidateWorker(symbol, input); + } + let i = 0; + const original = input; + while (context.usedSymbolNames?.has(input)) { + i++; + input = `${original}_${i}`; + } + context.usedSymbolNames?.add(input); + if (id) { + context.remappedSymbolNames!.set(id, input); + } + return input; + } + + function getNameCandidateWorker(symbol: Symbol, localName: string) { + if (localName === InternalSymbolName.Default || localName === InternalSymbolName.Class || localName === InternalSymbolName.Function) { + const flags = context.flags; + context.flags |= NodeBuilderFlags.InInitialEntityName; + const nameCandidate = getNameOfSymbolAsWritten(symbol, context); + context.flags = flags; + localName = nameCandidate.length > 0 && isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? stripQuotes(nameCandidate) : nameCandidate; + } + if (localName === InternalSymbolName.Default) { + localName = "_default"; + } + else if (localName === InternalSymbolName.ExportEquals) { + localName = "_exports"; + } + localName = isIdentifierText(localName, languageVersion) && !isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_"); + return localName; + } + + function getInternalSymbolName(symbol: Symbol, localName: string) { + const id = getSymbolId(symbol); + if (context.remappedSymbolNames!.has(id)) { + return context.remappedSymbolNames!.get(id)!; + } + localName = getNameCandidateWorker(symbol, localName); + // The result of this is going to be used as the symbol's name - lock it in, so `getUnusedName` will also pick it up + context.remappedSymbolNames!.set(id, localName); + return localName; + } + } + } + + function typePredicateToString(typePredicate: TypePredicate, enclosingDeclaration?: Node, flags: TypeFormatFlags = TypeFormatFlags.UseAliasDefinedOutsideCurrentScope, writer?: EmitTextWriter): string { + return writer ? typePredicateToStringWorker(writer).getText() : usingSingleLineStringWriter(typePredicateToStringWorker); + + function typePredicateToStringWorker(writer: EmitTextWriter) { + const nodeBuilderFlags = toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.WriteTypeParametersInQualifiedName; + const predicate = nodeBuilder.typePredicateToTypePredicateNode(typePredicate, enclosingDeclaration, nodeBuilderFlags)!; // TODO: GH#18217 + const printer = createPrinterWithRemoveComments(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, predicate, /*sourceFile*/ sourceFile, writer); + return writer; + } + } + + function formatUnionTypes(types: readonly Type[]): Type[] { + const result: Type[] = []; + let flags = 0 as TypeFlags; + for (let i = 0; i < types.length; i++) { + const t = types[i]; + flags |= t.flags; + if (!(t.flags & TypeFlags.Nullable)) { + if (t.flags & (TypeFlags.BooleanLiteral | TypeFlags.EnumLike)) { + const baseType = t.flags & TypeFlags.BooleanLiteral ? booleanType : getBaseTypeOfEnumLikeType(t as LiteralType); + if (baseType.flags & TypeFlags.Union) { + const count = (baseType as UnionType).types.length; + if (i + count <= types.length && getRegularTypeOfLiteralType(types[i + count - 1]) === getRegularTypeOfLiteralType((baseType as UnionType).types[count - 1])) { + result.push(baseType); + i += count - 1; + continue; + } + } + } + result.push(t); + } + } + if (flags & TypeFlags.Null) result.push(nullType); + if (flags & TypeFlags.Undefined) result.push(undefinedType); + return result || types; + } + + function visibilityToString(flags: ModifierFlags): string { + if (flags === ModifierFlags.Private) { + return "private"; + } + if (flags === ModifierFlags.Protected) { + return "protected"; + } + return "public"; + } + + function getTypeAliasForTypeLiteral(type: Type): Symbol | undefined { + if (type.symbol && type.symbol.flags & SymbolFlags.TypeLiteral && type.symbol.declarations) { + const node = walkUpParenthesizedTypes(type.symbol.declarations[0].parent); + if (isTypeAliasDeclaration(node)) { + return getSymbolOfDeclaration(node); + } + } + return undefined; + } + + function isTopLevelInExternalModuleAugmentation(node: Node): boolean { + return node && node.parent && + node.parent.kind === SyntaxKind.ModuleBlock && + isExternalModuleAugmentation(node.parent.parent); + } + + function isDefaultBindingContext(location: Node) { + return location.kind === SyntaxKind.SourceFile || isAmbientModule(location); + } + + function getNameOfSymbolFromNameType(symbol: Symbol, context?: NodeBuilderContext) { + const nameType = getSymbolLinks(symbol).nameType; + if (nameType) { + if (nameType.flags & TypeFlags.StringOrNumberLiteral) { + const name = "" + (nameType as StringLiteralType | NumberLiteralType).value; + if (!isIdentifierText(name, getEmitScriptTarget(compilerOptions)) && !isNumericLiteralName(name)) { + return `"${escapeString(name, CharacterCodes.doubleQuote)}"`; + } + if (isNumericLiteralName(name) && startsWith(name, "-")) { + return `[${name}]`; + } + return name; + } + if (nameType.flags & TypeFlags.UniqueESSymbol) { + return `[${getNameOfSymbolAsWritten((nameType as UniqueESSymbolType).symbol, context)}]`; + } + } + } + + /** + * Gets a human-readable name for a symbol. + * Should *not* be used for the right-hand side of a `.` -- use `symbolName(symbol)` for that instead. + * + * Unlike `symbolName(symbol)`, this will include quotes if the name is from a string literal. + * It will also use a representation of a number as written instead of a decimal form, e.g. `0o11` instead of `9`. + */ + function getNameOfSymbolAsWritten(symbol: Symbol, context?: NodeBuilderContext): string { + if (context?.remappedSymbolReferences?.has(getSymbolId(symbol))) { + symbol = context.remappedSymbolReferences.get(getSymbolId(symbol))!; + } + if ( + context && symbol.escapedName === InternalSymbolName.Default && !(context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope) && + // If it's not the first part of an entity name, it must print as `default` + (!(context.flags & NodeBuilderFlags.InInitialEntityName) || + // if the symbol is synthesized, it will only be referenced externally it must print as `default` + !symbol.declarations || + // if not in the same binding context (source file, module declaration), it must print as `default` + (context.enclosingDeclaration && findAncestor(symbol.declarations[0], isDefaultBindingContext) !== findAncestor(context.enclosingDeclaration, isDefaultBindingContext))) + ) { + return "default"; + } + if (symbol.declarations && symbol.declarations.length) { + let declaration = firstDefined(symbol.declarations, d => getNameOfDeclaration(d) ? d : undefined); // Try using a declaration with a name, first + const name = declaration && getNameOfDeclaration(declaration); + if (declaration && name) { + if (isCallExpression(declaration) && isBindableObjectDefinePropertyCall(declaration)) { + return symbolName(symbol); + } + if (isComputedPropertyName(name) && !(getCheckFlags(symbol) & CheckFlags.Late)) { + const nameType = getSymbolLinks(symbol).nameType; + if (nameType && nameType.flags & TypeFlags.StringOrNumberLiteral) { + // Computed property name isn't late bound, but has a well-known name type - use name type to generate a symbol name + const result = getNameOfSymbolFromNameType(symbol, context); + if (result !== undefined) { + return result; + } + } + } + return declarationNameToString(name); + } + if (!declaration) { + declaration = symbol.declarations[0]; // Declaration may be nameless, but we'll try anyway + } + if (declaration.parent && declaration.parent.kind === SyntaxKind.VariableDeclaration) { + return declarationNameToString((declaration.parent as VariableDeclaration).name); + } + switch (declaration.kind) { + case SyntaxKind.ClassExpression: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + if (context && !context.encounteredError && !(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier)) { + context.encounteredError = true; + } + return declaration.kind === SyntaxKind.ClassExpression ? "(Anonymous class)" : "(Anonymous function)"; + } + } + const name = getNameOfSymbolFromNameType(symbol, context); + return name !== undefined ? name : symbolName(symbol); + } + + function isDeclarationVisible(node: Node): boolean { + if (node) { + const links = getNodeLinks(node); + if (links.isVisible === undefined) { + links.isVisible = !!determineIfDeclarationIsVisible(); + } + return links.isVisible; + } + + return false; + + function determineIfDeclarationIsVisible() { + switch (node.kind) { + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocEnumTag: + // Top-level jsdoc type aliases are considered exported + // First parent is comment node, second is hosting declaration or token; we only care about those tokens or declarations whose parent is a source file + return !!(node.parent && node.parent.parent && node.parent.parent.parent && isSourceFile(node.parent.parent.parent)); + case SyntaxKind.BindingElement: + return isDeclarationVisible(node.parent.parent); + case SyntaxKind.VariableDeclaration: + if ( + isBindingPattern((node as VariableDeclaration).name) && + !((node as VariableDeclaration).name as BindingPattern).elements.length + ) { + // If the binding pattern is empty, this variable declaration is not visible + return false; + } + // falls through + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.ImportEqualsDeclaration: + // external module augmentation is always visible + if (isExternalModuleAugmentation(node)) { + return true; + } + const parent = getDeclarationContainer(node); + // If the node is not exported or it is not ambient module element (except import declaration) + if ( + !(getCombinedModifierFlagsCached(node as Declaration) & ModifierFlags.Export) && + !(node.kind !== SyntaxKind.ImportEqualsDeclaration && parent.kind !== SyntaxKind.SourceFile && parent.flags & NodeFlags.Ambient) + ) { + return isGlobalSourceFile(parent); + } + // Exported members/ambient module elements (exception import declaration) are visible if parent is visible + return isDeclarationVisible(parent); + + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + if (hasEffectiveModifier(node, ModifierFlags.Private | ModifierFlags.Protected)) { + // Private/protected properties/methods are not visible + return false; + } + // Public properties/methods are visible if its parents are visible, so: + // falls through + + case SyntaxKind.Constructor: + case SyntaxKind.ConstructSignature: + case SyntaxKind.CallSignature: + case SyntaxKind.IndexSignature: + case SyntaxKind.Parameter: + case SyntaxKind.ModuleBlock: + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.TypeLiteral: + case SyntaxKind.TypeReference: + case SyntaxKind.ArrayType: + case SyntaxKind.TupleType: + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + case SyntaxKind.ParenthesizedType: + case SyntaxKind.NamedTupleMember: + return isDeclarationVisible(node.parent); + + // Default binding, import specifier and namespace import is visible + // only on demand so by default it is not visible + case SyntaxKind.ImportClause: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportSpecifier: + return false; + + // Type parameters are always visible + case SyntaxKind.TypeParameter: + + // Source file and namespace export are always visible + // falls through + case SyntaxKind.SourceFile: + case SyntaxKind.NamespaceExportDeclaration: + return true; + + // Export assignments do not create name bindings outside the module + case SyntaxKind.ExportAssignment: + return false; + + default: + return false; + } + } + } + + function collectLinkedAliases(node: ModuleExportName, setVisibility?: boolean): Node[] | undefined { + let exportSymbol: Symbol | undefined; + if (node.kind !== SyntaxKind.StringLiteral && node.parent && node.parent.kind === SyntaxKind.ExportAssignment) { + exportSymbol = resolveName(node, node, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + } + else if (node.parent.kind === SyntaxKind.ExportSpecifier) { + exportSymbol = getTargetOfExportSpecifier(node.parent as ExportSpecifier, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); + } + let result: Node[] | undefined; + let visited: Set | undefined; + if (exportSymbol) { + visited = new Set(); + visited.add(getSymbolId(exportSymbol)); + buildVisibleNodeList(exportSymbol.declarations); + } + return result; + + function buildVisibleNodeList(declarations: Declaration[] | undefined) { + forEach(declarations, declaration => { + const resultNode = getAnyImportSyntax(declaration) || declaration; + if (setVisibility) { + getNodeLinks(declaration).isVisible = true; + } + else { + result = result || []; + pushIfUnique(result, resultNode); + } + + if (isInternalModuleImportEqualsDeclaration(declaration)) { + // Add the referenced top container visible + const internalModuleReference = declaration.moduleReference as Identifier | QualifiedName; + const firstIdentifier = getFirstIdentifier(internalModuleReference); + const importSymbol = resolveName(declaration, firstIdentifier.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (importSymbol && visited) { + if (tryAddToSet(visited, getSymbolId(importSymbol))) { + buildVisibleNodeList(importSymbol.declarations); + } + } + } + }); + } + } + + /** + * Push an entry on the type resolution stack. If an entry with the given target and the given property name + * is already on the stack, and no entries in between already have a type, then a circularity has occurred. + * In this case, the result values of the existing entry and all entries pushed after it are changed to false, + * and the value false is returned. Otherwise, the new entry is just pushed onto the stack, and true is returned. + * In order to see if the same query has already been done before, the target object and the propertyName both + * must match the one passed in. + * + * @param target The symbol, type, or signature whose type is being queried + * @param propertyName The property name that should be used to query the target for its type + */ + function pushTypeResolution(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): boolean { + const resolutionCycleStartIndex = findResolutionCycleStartIndex(target, propertyName); + if (resolutionCycleStartIndex >= 0) { + // A cycle was found + const { length } = resolutionTargets; + for (let i = resolutionCycleStartIndex; i < length; i++) { + resolutionResults[i] = false; + } + return false; + } + resolutionTargets.push(target); + resolutionResults.push(/*items*/ true); + resolutionPropertyNames.push(propertyName); + return true; + } + + function findResolutionCycleStartIndex(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): number { + for (let i = resolutionTargets.length - 1; i >= resolutionStart; i--) { + if (resolutionTargetHasProperty(resolutionTargets[i], resolutionPropertyNames[i])) { + return -1; + } + if (resolutionTargets[i] === target && resolutionPropertyNames[i] === propertyName) { + return i; + } + } + return -1; + } + + function resolutionTargetHasProperty(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): boolean { + switch (propertyName) { + case TypeSystemPropertyName.Type: + return !!getSymbolLinks(target as Symbol).type; + case TypeSystemPropertyName.DeclaredType: + return !!getSymbolLinks(target as Symbol).declaredType; + case TypeSystemPropertyName.ResolvedBaseConstructorType: + return !!(target as InterfaceType).resolvedBaseConstructorType; + case TypeSystemPropertyName.ResolvedReturnType: + return !!(target as Signature).resolvedReturnType; + case TypeSystemPropertyName.ImmediateBaseConstraint: + return !!(target as Type).immediateBaseConstraint; + case TypeSystemPropertyName.ResolvedTypeArguments: + return !!(target as TypeReference).resolvedTypeArguments; + case TypeSystemPropertyName.ResolvedBaseTypes: + return !!(target as InterfaceType).baseTypesResolved; + case TypeSystemPropertyName.WriteType: + return !!getSymbolLinks(target as Symbol).writeType; + case TypeSystemPropertyName.ParameterInitializerContainsUndefined: + return getNodeLinks(target as ParameterDeclaration).parameterInitializerContainsUndefined !== undefined; + } + return Debug.assertNever(propertyName); + } + + /** + * Pop an entry from the type resolution stack and return its associated result value. The result value will + * be true if no circularities were detected, or false if a circularity was found. + */ + function popTypeResolution(): boolean { + resolutionTargets.pop(); + resolutionPropertyNames.pop(); + return resolutionResults.pop()!; + } + + function getDeclarationContainer(node: Node): Node { + return findAncestor(getRootDeclaration(node), node => { + switch (node.kind) { + case SyntaxKind.VariableDeclaration: + case SyntaxKind.VariableDeclarationList: + case SyntaxKind.ImportSpecifier: + case SyntaxKind.NamedImports: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportClause: + return false; + default: + return true; + } + })!.parent; + } + + function getTypeOfPrototypeProperty(prototype: Symbol): Type { + // TypeScript 1.0 spec (April 2014): 8.4 + // Every class automatically contains a static property member named 'prototype', + // the type of which is an instantiation of the class type with type Any supplied as a type argument for each type parameter. + // It is an error to explicitly declare a static property member with the name 'prototype'. + const classType = getDeclaredTypeOfSymbol(getParentOfSymbol(prototype)!) as InterfaceType; + return classType.typeParameters ? createTypeReference(classType as GenericType, map(classType.typeParameters, _ => anyType)) : classType; + } + + // Return the type of the given property in the given type, or undefined if no such property exists + function getTypeOfPropertyOfType(type: Type, name: __String): Type | undefined { + const prop = getPropertyOfType(type, name); + return prop ? getTypeOfSymbol(prop) : undefined; + } + + /** + * Return the type of the matching property or index signature in the given type, or undefined + * if no matching property or index signature exists. Add optionality to index signature types. + */ + function getTypeOfPropertyOrIndexSignatureOfType(type: Type, name: __String): Type | undefined { + let propType; + return getTypeOfPropertyOfType(type, name) || + (propType = getApplicableIndexInfoForName(type, name)?.type) && + addOptionality(propType, /*isProperty*/ true, /*isOptional*/ true); + } + + function isTypeAny(type: Type | undefined) { + return type && (type.flags & TypeFlags.Any) !== 0; + } + + function isErrorType(type: Type) { + // The only 'any' types that have alias symbols are those manufactured by getTypeFromTypeAliasReference for + // a reference to an unresolved symbol. We want those to behave like the errorType. + return type === errorType || !!(type.flags & TypeFlags.Any && type.aliasSymbol); + } + + // Return the type of a binding element parent. We check SymbolLinks first to see if a type has been + // assigned by contextual typing. + function getTypeForBindingElementParent(node: BindingElementGrandparent, checkMode: CheckMode) { + if (checkMode !== CheckMode.Normal) { + return getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ false, checkMode); + } + const symbol = getSymbolOfDeclaration(node); + return symbol && getSymbolLinks(symbol).type || getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ false, checkMode); + } + + function getRestType(source: Type, properties: PropertyName[], symbol: Symbol | undefined): Type { + source = filterType(source, t => !(t.flags & TypeFlags.Nullable)); + if (source.flags & TypeFlags.Never) { + return emptyObjectType; + } + if (source.flags & TypeFlags.Union) { + return mapType(source, t => getRestType(t, properties, symbol)); + } + + let omitKeyType = getUnionType(map(properties, getLiteralTypeFromPropertyName)); + + const spreadableProperties: Symbol[] = []; + const unspreadableToRestKeys: Type[] = []; + + for (const prop of getPropertiesOfType(source)) { + const literalTypeFromProperty = getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique); + if ( + !isTypeAssignableTo(literalTypeFromProperty, omitKeyType) + && !(getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) + && isSpreadableProperty(prop) + ) { + spreadableProperties.push(prop); + } + else { + unspreadableToRestKeys.push(literalTypeFromProperty); + } + } + + if (isGenericObjectType(source) || isGenericIndexType(omitKeyType)) { + if (unspreadableToRestKeys.length) { + // If the type we're spreading from has properties that cannot + // be spread into the rest type (e.g. getters, methods), ensure + // they are explicitly omitted, as they would in the non-generic case. + omitKeyType = getUnionType([omitKeyType, ...unspreadableToRestKeys]); + } + + if (omitKeyType.flags & TypeFlags.Never) { + return source; + } + + const omitTypeAlias = getGlobalOmitSymbol(); + if (!omitTypeAlias) { + return errorType; + } + return getTypeAliasInstantiation(omitTypeAlias, [source, omitKeyType]); + } + const members = createSymbolTable(); + for (const prop of spreadableProperties) { + members.set(prop.escapedName, getSpreadSymbol(prop, /*readonly*/ false)); + } + const result = createAnonymousType(symbol, members, emptyArray, emptyArray, getIndexInfosOfType(source)); + result.objectFlags |= ObjectFlags.ObjectRestType; + return result; + } + + function isGenericTypeWithUndefinedConstraint(type: Type) { + return !!(type.flags & TypeFlags.Instantiable) && maybeTypeOfKind(getBaseConstraintOfType(type) || unknownType, TypeFlags.Undefined); + } + + function getNonUndefinedType(type: Type) { + const typeOrConstraint = someType(type, isGenericTypeWithUndefinedConstraint) ? mapType(type, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOrType(t) : t) : type; + return getTypeWithFacts(typeOrConstraint, TypeFacts.NEUndefined); + } + + // Determine the control flow type associated with a destructuring declaration or assignment. The following + // forms of destructuring are possible: + // let { x } = obj; // BindingElement + // let [ x ] = obj; // BindingElement + // { x } = obj; // ShorthandPropertyAssignment + // { x: v } = obj; // PropertyAssignment + // [ x ] = obj; // Expression + // We construct a synthetic element access expression corresponding to 'obj.x' such that the control + // flow analyzer doesn't have to handle all the different syntactic forms. + function getFlowTypeOfDestructuring(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression, declaredType: Type) { + const reference = getSyntheticElementAccess(node); + return reference ? getFlowTypeOfReference(reference, declaredType) : declaredType; + } + + function getSyntheticElementAccess(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression): ElementAccessExpression | undefined { + const parentAccess = getParentElementAccess(node); + if (parentAccess && canHaveFlowNode(parentAccess) && parentAccess.flowNode) { + const propName = getDestructuringPropertyName(node); + if (propName) { + const literal = setTextRangeWorker(parseNodeFactory.createStringLiteral(propName), node); + const lhsExpr = isLeftHandSideExpression(parentAccess) ? parentAccess : parseNodeFactory.createParenthesizedExpression(parentAccess); + const result = setTextRangeWorker(parseNodeFactory.createElementAccessExpression(lhsExpr, literal), node); + setParent(literal, result); + setParent(result, node); + if (lhsExpr !== parentAccess) { + setParent(lhsExpr, result); + } + result.flowNode = parentAccess.flowNode; + return result; + } + } + } + + function getParentElementAccess(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression) { + const ancestor = node.parent.parent; + switch (ancestor.kind) { + case SyntaxKind.BindingElement: + case SyntaxKind.PropertyAssignment: + return getSyntheticElementAccess(ancestor as BindingElement | PropertyAssignment); + case SyntaxKind.ArrayLiteralExpression: + return getSyntheticElementAccess(node.parent as Expression); + case SyntaxKind.VariableDeclaration: + return (ancestor as VariableDeclaration).initializer; + case SyntaxKind.BinaryExpression: + return (ancestor as BinaryExpression).right; + } + } + + function getDestructuringPropertyName(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression) { + const parent = node.parent; + if (node.kind === SyntaxKind.BindingElement && parent.kind === SyntaxKind.ObjectBindingPattern) { + return getLiteralPropertyNameText((node as BindingElement).propertyName || (node as BindingElement).name as Identifier); + } + if (node.kind === SyntaxKind.PropertyAssignment || node.kind === SyntaxKind.ShorthandPropertyAssignment) { + return getLiteralPropertyNameText((node as PropertyAssignment | ShorthandPropertyAssignment).name); + } + return "" + ((parent as BindingPattern | ArrayLiteralExpression).elements as NodeArray).indexOf(node); + } + + function getLiteralPropertyNameText(name: PropertyName) { + const type = getLiteralTypeFromPropertyName(name); + return type.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral) ? "" + (type as StringLiteralType | NumberLiteralType).value : undefined; + } + + /** Return the inferred type for a binding element */ + function getTypeForBindingElement(declaration: BindingElement): Type | undefined { + const checkMode = declaration.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal; + const parentType = getTypeForBindingElementParent(declaration.parent.parent, checkMode); + return parentType && getBindingElementTypeFromParentType(declaration, parentType, /*noTupleBoundsCheck*/ false); + } + + function getBindingElementTypeFromParentType(declaration: BindingElement, parentType: Type, noTupleBoundsCheck: boolean): Type { + // If an any type was inferred for parent, infer that for the binding element + if (isTypeAny(parentType)) { + return parentType; + } + const pattern = declaration.parent; + // Relax null check on ambient destructuring parameters, since the parameters have no implementation and are just documentation + if (strictNullChecks && declaration.flags & NodeFlags.Ambient && isPartOfParameterDeclaration(declaration)) { + parentType = getNonNullableType(parentType); + } + // Filter `undefined` from the type we check against if the parent has an initializer and that initializer is not possibly `undefined` + else if (strictNullChecks && pattern.parent.initializer && !(hasTypeFacts(getTypeOfInitializer(pattern.parent.initializer), TypeFacts.EQUndefined))) { + parentType = getTypeWithFacts(parentType, TypeFacts.NEUndefined); + } + + let type: Type | undefined; + if (pattern.kind === SyntaxKind.ObjectBindingPattern) { + if (declaration.dotDotDotToken) { + parentType = getReducedType(parentType); + if (parentType.flags & TypeFlags.Unknown || !isValidSpreadType(parentType)) { + error(declaration, Diagnostics.Rest_types_may_only_be_created_from_object_types); + return errorType; + } + const literalMembers: PropertyName[] = []; + for (const element of pattern.elements) { + if (!element.dotDotDotToken) { + literalMembers.push(element.propertyName || element.name as Identifier); + } + } + type = getRestType(parentType, literalMembers, declaration.symbol); + } + else { + // Use explicitly specified property name ({ p: xxx } form), or otherwise the implied name ({ p } form) + const name = declaration.propertyName || declaration.name as Identifier; + const indexType = getLiteralTypeFromPropertyName(name); + const declaredType = getIndexedAccessType(parentType, indexType, AccessFlags.ExpressionPosition, name); + type = getFlowTypeOfDestructuring(declaration, declaredType); + } + } + else { + // This elementType will be used if the specific property corresponding to this index is not + // present (aka the tuple element property). This call also checks that the parentType is in + // fact an iterable or array (depending on target language). + const elementType = checkIteratedTypeOrElementType(IterationUse.Destructuring | (declaration.dotDotDotToken ? 0 : IterationUse.PossiblyOutOfBounds), parentType, undefinedType, pattern); + const index = pattern.elements.indexOf(declaration); + if (declaration.dotDotDotToken) { + // If the parent is a tuple type, the rest element has a tuple type of the + // remaining tuple element types. Otherwise, the rest element has an array type with same + // element type as the parent type. + const baseConstraint = mapType(parentType, t => t.flags & TypeFlags.InstantiableNonPrimitive ? getBaseConstraintOrType(t) : t); + type = everyType(baseConstraint, isTupleType) ? + mapType(baseConstraint, t => sliceTupleType(t as TupleTypeReference, index)) : + createArrayType(elementType); + } + else if (isArrayLikeType(parentType)) { + const indexType = getNumberLiteralType(index); + const accessFlags = AccessFlags.ExpressionPosition | (noTupleBoundsCheck || hasDefaultValue(declaration) ? AccessFlags.NoTupleBoundsCheck : 0); + const declaredType = getIndexedAccessTypeOrUndefined(parentType, indexType, accessFlags, declaration.name) || errorType; + type = getFlowTypeOfDestructuring(declaration, declaredType); + } + else { + type = elementType; + } + } + if (!declaration.initializer) { + return type; + } + if (getEffectiveTypeAnnotationNode(walkUpBindingElementsAndPatterns(declaration))) { + // In strict null checking mode, if a default value of a non-undefined type is specified, remove + // undefined from the final type. + return strictNullChecks && !(hasTypeFacts(checkDeclarationInitializer(declaration, CheckMode.Normal), TypeFacts.IsUndefined)) ? getNonUndefinedType(type) : type; + } + return widenTypeInferredFromInitializer(declaration, getUnionType([getNonUndefinedType(type), checkDeclarationInitializer(declaration, CheckMode.Normal)], UnionReduction.Subtype)); + } + + function getTypeForDeclarationFromJSDocComment(declaration: Node) { + const jsdocType = getJSDocType(declaration); + if (jsdocType) { + return getTypeFromTypeNode(jsdocType); + } + return undefined; + } + + function isNullOrUndefined(node: Expression) { + const expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + return expr.kind === SyntaxKind.NullKeyword || expr.kind === SyntaxKind.Identifier && getResolvedSymbol(expr as Identifier) === undefinedSymbol; + } + + function isEmptyArrayLiteral(node: Expression) { + const expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + return expr.kind === SyntaxKind.ArrayLiteralExpression && (expr as ArrayLiteralExpression).elements.length === 0; + } + + function addOptionality(type: Type, isProperty = false, isOptional = true): Type { + return strictNullChecks && isOptional ? getOptionalType(type, isProperty) : type; + } + + // Return the inferred type for a variable, parameter, or property declaration + function getTypeForVariableLikeDeclaration( + declaration: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement | JSDocPropertyLikeTag, + includeOptionality: boolean, + checkMode: CheckMode, + ): Type | undefined { + // A variable declared in a for..in statement is of type string, or of type keyof T when the + // right hand expression is of a type parameter type. + if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForInStatement) { + const indexType = getIndexType(getNonNullableTypeIfNeeded(checkExpression(declaration.parent.parent.expression, /*checkMode*/ checkMode))); + return indexType.flags & (TypeFlags.TypeParameter | TypeFlags.Index) ? getExtractStringType(indexType) : stringType; + } + + if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForOfStatement) { + // checkRightHandSideOfForOf will return undefined if the for-of expression type was + // missing properties/signatures required to get its iteratedType (like + // [Symbol.iterator] or next). This may be because we accessed properties from anyType, + // or it may have led to an error inside getElementTypeOfIterable. + const forOfStatement = declaration.parent.parent; + return checkRightHandSideOfForOf(forOfStatement) || anyType; + } + + if (isBindingPattern(declaration.parent)) { + return getTypeForBindingElement(declaration as BindingElement); + } + + const isProperty = (isPropertyDeclaration(declaration) && !hasAccessorModifier(declaration)) || isPropertySignature(declaration) || isJSDocPropertyTag(declaration); + const isOptional = includeOptionality && isOptionalDeclaration(declaration); + + // Use type from type annotation if one is present + const declaredType = tryGetTypeFromEffectiveTypeNode(declaration); + if (isCatchClauseVariableDeclarationOrBindingElement(declaration)) { + if (declaredType) { + // If the catch clause is explicitly annotated with any or unknown, accept it, otherwise error. + return isTypeAny(declaredType) || declaredType === unknownType ? declaredType : errorType; + } + // If the catch clause is not explicitly annotated, treat it as though it were explicitly + // annotated with unknown or any, depending on useUnknownInCatchVariables. + return useUnknownInCatchVariables ? unknownType : anyType; + } + if (declaredType) { + return addOptionality(declaredType, isProperty, isOptional); + } + + if ( + (noImplicitAny || isInJSFile(declaration)) && + isVariableDeclaration(declaration) && !isBindingPattern(declaration.name) && + !(getCombinedModifierFlagsCached(declaration) & ModifierFlags.Export) && !(declaration.flags & NodeFlags.Ambient) + ) { + // If --noImplicitAny is on or the declaration is in a Javascript file, + // use control flow tracked 'any' type for non-ambient, non-exported var or let variables with no + // initializer or a 'null' or 'undefined' initializer. + if (!(getCombinedNodeFlagsCached(declaration) & NodeFlags.Constant) && (!declaration.initializer || isNullOrUndefined(declaration.initializer))) { + return autoType; + } + // Use control flow tracked 'any[]' type for non-ambient, non-exported variables with an empty array + // literal initializer. + if (declaration.initializer && isEmptyArrayLiteral(declaration.initializer)) { + return autoArrayType; + } + } + + if (isParameter(declaration)) { + if (!declaration.symbol) { + // parameters of function types defined in JSDoc in TS files don't have symbols + return; + } + const func = declaration.parent as FunctionLikeDeclaration; + // For a parameter of a set accessor, use the type of the get accessor if one is present + if (func.kind === SyntaxKind.SetAccessor && hasBindableName(func)) { + const getter = getDeclarationOfKind(getSymbolOfDeclaration(declaration.parent), SyntaxKind.GetAccessor); + if (getter) { + const getterSignature = getSignatureFromDeclaration(getter); + const thisParameter = getAccessorThisParameter(func as AccessorDeclaration); + if (thisParameter && declaration === thisParameter) { + // Use the type from the *getter* + Debug.assert(!thisParameter.type); + return getTypeOfSymbol(getterSignature.thisParameter!); + } + return getReturnTypeOfSignature(getterSignature); + } + } + const parameterTypeOfTypeTag = getParameterTypeOfTypeTag(func, declaration); + if (parameterTypeOfTypeTag) return parameterTypeOfTypeTag; + // Use contextual parameter type if one is available + const type = declaration.symbol.escapedName === InternalSymbolName.This ? getContextualThisParameterType(func) : getContextuallyTypedParameterType(declaration); + if (type) { + return addOptionality(type, /*isProperty*/ false, isOptional); + } + } + + // Use the type of the initializer expression if one is present and the declaration is + // not a parameter of a contextually typed function + if (hasOnlyExpressionInitializer(declaration) && !!declaration.initializer) { + if (isInJSFile(declaration) && !isParameter(declaration)) { + const containerObjectType = getJSContainerObjectType(declaration, getSymbolOfDeclaration(declaration), getDeclaredExpandoInitializer(declaration)); + if (containerObjectType) { + return containerObjectType; + } + } + const type = widenTypeInferredFromInitializer(declaration, checkDeclarationInitializer(declaration, checkMode)); + return addOptionality(type, isProperty, isOptional); + } + + if (isPropertyDeclaration(declaration) && (noImplicitAny || isInJSFile(declaration))) { + // We have a property declaration with no type annotation or initializer, in noImplicitAny mode or a .js file. + // Use control flow analysis of this.xxx assignments in the constructor or static block to determine the type of the property. + if (!hasStaticModifier(declaration)) { + const constructor = findConstructorDeclaration(declaration.parent); + const type = constructor ? getFlowTypeInConstructor(declaration.symbol, constructor) : + getEffectiveModifierFlags(declaration) & ModifierFlags.Ambient ? getTypeOfPropertyInBaseClass(declaration.symbol) : + undefined; + return type && addOptionality(type, /*isProperty*/ true, isOptional); + } + else { + const staticBlocks = filter(declaration.parent.members, isClassStaticBlockDeclaration); + const type = staticBlocks.length ? getFlowTypeInStaticBlocks(declaration.symbol, staticBlocks) : + getEffectiveModifierFlags(declaration) & ModifierFlags.Ambient ? getTypeOfPropertyInBaseClass(declaration.symbol) : + undefined; + return type && addOptionality(type, /*isProperty*/ true, isOptional); + } + } + + if (isJsxAttribute(declaration)) { + // if JSX attribute doesn't have initializer, by default the attribute will have boolean value of true. + // I.e is sugar for + return trueType; + } + + // If the declaration specifies a binding pattern and is not a parameter of a contextually + // typed function, use the type implied by the binding pattern + if (isBindingPattern(declaration.name)) { + return getTypeFromBindingPattern(declaration.name, /*includePatternInType*/ false, /*reportErrors*/ true); + } + + // No type specified and nothing can be inferred + return undefined; + } + + function isConstructorDeclaredProperty(symbol: Symbol) { + // A property is considered a constructor declared property when all declaration sites are this.xxx assignments, + // when no declaration sites have JSDoc type annotations, and when at least one declaration site is in the body of + // a class constructor. + if (symbol.valueDeclaration && isBinaryExpression(symbol.valueDeclaration)) { + const links = getSymbolLinks(symbol); + if (links.isConstructorDeclaredProperty === undefined) { + links.isConstructorDeclaredProperty = false; + links.isConstructorDeclaredProperty = !!getDeclaringConstructor(symbol) && every(symbol.declarations, declaration => + isBinaryExpression(declaration) && + isPossiblyAliasedThisProperty(declaration) && + (declaration.left.kind !== SyntaxKind.ElementAccessExpression || isStringOrNumericLiteralLike((declaration.left as ElementAccessExpression).argumentExpression)) && + !getAnnotatedTypeForAssignmentDeclaration(/*declaredType*/ undefined, declaration, symbol, declaration)); + } + return links.isConstructorDeclaredProperty; + } + return false; + } + + function isAutoTypedProperty(symbol: Symbol) { + // A property is auto-typed when its declaration has no type annotation or initializer and we're in + // noImplicitAny mode or a .js file. + const declaration = symbol.valueDeclaration; + return declaration && isPropertyDeclaration(declaration) && !getEffectiveTypeAnnotationNode(declaration) && + !declaration.initializer && (noImplicitAny || isInJSFile(declaration)); + } + + function getDeclaringConstructor(symbol: Symbol) { + if (!symbol.declarations) { + return; + } + for (const declaration of symbol.declarations) { + const container = getThisContainer(declaration, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (container && (container.kind === SyntaxKind.Constructor || isJSConstructor(container))) { + return container as ConstructorDeclaration; + } + } + } + + /** Create a synthetic property access flow node after the last statement of the file */ + function getFlowTypeFromCommonJSExport(symbol: Symbol) { + const file = getSourceFileOfNode(symbol.declarations![0]); + const accessName = unescapeLeadingUnderscores(symbol.escapedName); + const areAllModuleExports = symbol.declarations!.every(d => isInJSFile(d) && isAccessExpression(d) && isModuleExportsAccessExpression(d.expression)); + const reference = areAllModuleExports + ? factory.createPropertyAccessExpression(factory.createPropertyAccessExpression(factory.createIdentifier("module"), factory.createIdentifier("exports")), accessName) + : factory.createPropertyAccessExpression(factory.createIdentifier("exports"), accessName); + if (areAllModuleExports) { + setParent((reference.expression as PropertyAccessExpression).expression, reference.expression); + } + setParent(reference.expression, reference); + setParent(reference, file); + reference.flowNode = file.endFlowNode; + return getFlowTypeOfReference(reference, autoType, undefinedType); + } + + function getFlowTypeInStaticBlocks(symbol: Symbol, staticBlocks: readonly ClassStaticBlockDeclaration[]) { + const accessName = startsWith(symbol.escapedName as string, "__#") + ? factory.createPrivateIdentifier((symbol.escapedName as string).split("@")[1]) + : unescapeLeadingUnderscores(symbol.escapedName); + for (const staticBlock of staticBlocks) { + const reference = factory.createPropertyAccessExpression(factory.createThis(), accessName); + setParent(reference.expression, reference); + setParent(reference, staticBlock); + reference.flowNode = staticBlock.returnFlowNode; + const flowType = getFlowTypeOfProperty(reference, symbol); + if (noImplicitAny && (flowType === autoType || flowType === autoArrayType)) { + error(symbol.valueDeclaration, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); + } + // We don't infer a type if assignments are only null or undefined. + if (everyType(flowType, isNullableType)) { + continue; + } + return convertAutoToAny(flowType); + } + } + + function getFlowTypeInConstructor(symbol: Symbol, constructor: ConstructorDeclaration) { + const accessName = startsWith(symbol.escapedName as string, "__#") + ? factory.createPrivateIdentifier((symbol.escapedName as string).split("@")[1]) + : unescapeLeadingUnderscores(symbol.escapedName); + const reference = factory.createPropertyAccessExpression(factory.createThis(), accessName); + setParent(reference.expression, reference); + setParent(reference, constructor); + reference.flowNode = constructor.returnFlowNode; + const flowType = getFlowTypeOfProperty(reference, symbol); + if (noImplicitAny && (flowType === autoType || flowType === autoArrayType)) { + error(symbol.valueDeclaration, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); + } + // We don't infer a type if assignments are only null or undefined. + return everyType(flowType, isNullableType) ? undefined : convertAutoToAny(flowType); + } + + function getFlowTypeOfProperty(reference: Node, prop: Symbol | undefined) { + const initialType = prop?.valueDeclaration + && (!isAutoTypedProperty(prop) || getEffectiveModifierFlags(prop.valueDeclaration) & ModifierFlags.Ambient) + && getTypeOfPropertyInBaseClass(prop) + || undefinedType; + return getFlowTypeOfReference(reference, autoType, initialType); + } + + function getWidenedTypeForAssignmentDeclaration(symbol: Symbol, resolvedSymbol?: Symbol) { + // function/class/{} initializers are themselves containers, so they won't merge in the same way as other initializers + const container = getAssignedExpandoInitializer(symbol.valueDeclaration); + if (container) { + const tag = isInJSFile(container) ? getJSDocTypeTag(container) : undefined; + if (tag && tag.typeExpression) { + return getTypeFromTypeNode(tag.typeExpression); + } + const containerObjectType = symbol.valueDeclaration && getJSContainerObjectType(symbol.valueDeclaration, symbol, container); + return containerObjectType || getWidenedLiteralType(checkExpressionCached(container)); + } + let type; + let definedInConstructor = false; + let definedInMethod = false; + // We use control flow analysis to determine the type of the property if the property qualifies as a constructor + // declared property and the resulting control flow type isn't just undefined or null. + if (isConstructorDeclaredProperty(symbol)) { + type = getFlowTypeInConstructor(symbol, getDeclaringConstructor(symbol)!); + } + if (!type) { + let types: Type[] | undefined; + if (symbol.declarations) { + let jsdocType: Type | undefined; + for (const declaration of symbol.declarations) { + const expression = (isBinaryExpression(declaration) || isCallExpression(declaration)) ? declaration : + isAccessExpression(declaration) ? isBinaryExpression(declaration.parent) ? declaration.parent : declaration : + undefined; + if (!expression) { + continue; // Non-assignment declaration merged in (eg, an Identifier to mark the thing as a namespace) - skip over it and pull type info from elsewhere + } + + const kind = isAccessExpression(expression) + ? getAssignmentDeclarationPropertyAccessKind(expression) + : getAssignmentDeclarationKind(expression); + if (kind === AssignmentDeclarationKind.ThisProperty || isBinaryExpression(expression) && isPossiblyAliasedThisProperty(expression, kind)) { + if (isDeclarationInConstructor(expression)) { + definedInConstructor = true; + } + else { + definedInMethod = true; + } + } + if (!isCallExpression(expression)) { + jsdocType = getAnnotatedTypeForAssignmentDeclaration(jsdocType, expression, symbol, declaration); + } + if (!jsdocType) { + (types || (types = [])).push((isBinaryExpression(expression) || isCallExpression(expression)) ? getInitializerTypeFromAssignmentDeclaration(symbol, resolvedSymbol, expression, kind) : neverType); + } + } + type = jsdocType; + } + if (!type) { + if (!length(types)) { + return errorType; // No types from any declarations :( + } + let constructorTypes = definedInConstructor && symbol.declarations ? getConstructorDefinedThisAssignmentTypes(types!, symbol.declarations) : undefined; + // use only the constructor types unless they were only assigned null | undefined (including widening variants) + if (definedInMethod) { + const propType = getTypeOfPropertyInBaseClass(symbol); + if (propType) { + (constructorTypes || (constructorTypes = [])).push(propType); + definedInConstructor = true; + } + } + const sourceTypes = some(constructorTypes, t => !!(t.flags & ~TypeFlags.Nullable)) ? constructorTypes : types; // TODO: GH#18217 + type = getUnionType(sourceTypes!); + } + } + const widened = getWidenedType(addOptionality(type, /*isProperty*/ false, definedInMethod && !definedInConstructor)); + if (symbol.valueDeclaration && isInJSFile(symbol.valueDeclaration) && filterType(widened, t => !!(t.flags & ~TypeFlags.Nullable)) === neverType) { + reportImplicitAny(symbol.valueDeclaration, anyType); + return anyType; + } + return widened; + } + + function getJSContainerObjectType(decl: Node, symbol: Symbol, init: Expression | undefined): Type | undefined { + if (!isInJSFile(decl) || !init || !isObjectLiteralExpression(init) || init.properties.length) { + return undefined; + } + const exports = createSymbolTable(); + while (isBinaryExpression(decl) || isPropertyAccessExpression(decl)) { + const s = getSymbolOfNode(decl); + if (s?.exports?.size) { + mergeSymbolTable(exports, s.exports); + } + decl = isBinaryExpression(decl) ? decl.parent : decl.parent.parent; + } + const s = getSymbolOfNode(decl); + if (s?.exports?.size) { + mergeSymbolTable(exports, s.exports); + } + const type = createAnonymousType(symbol, exports, emptyArray, emptyArray, emptyArray); + type.objectFlags |= ObjectFlags.JSLiteral; + return type; + } + + function getAnnotatedTypeForAssignmentDeclaration(declaredType: Type | undefined, expression: Expression, symbol: Symbol, declaration: Declaration) { + const typeNode = getEffectiveTypeAnnotationNode(expression.parent); + if (typeNode) { + const type = getWidenedType(getTypeFromTypeNode(typeNode)); + if (!declaredType) { + return type; + } + else if (!isErrorType(declaredType) && !isErrorType(type) && !isTypeIdenticalTo(declaredType, type)) { + errorNextVariableOrPropertyDeclarationMustHaveSameType(/*firstDeclaration*/ undefined, declaredType, declaration, type); + } + } + if (symbol.parent?.valueDeclaration) { + const possiblyAnnotatedSymbol = getFunctionExpressionParentSymbolOrSymbol(symbol.parent); + if (possiblyAnnotatedSymbol.valueDeclaration) { + const typeNode = getEffectiveTypeAnnotationNode(possiblyAnnotatedSymbol.valueDeclaration); + if (typeNode) { + const annotationSymbol = getPropertyOfType(getTypeFromTypeNode(typeNode), symbol.escapedName); + if (annotationSymbol) { + return getNonMissingTypeOfSymbol(annotationSymbol); + } + } + } + } + + return declaredType; + } + + /** If we don't have an explicit JSDoc type, get the type from the initializer. */ + function getInitializerTypeFromAssignmentDeclaration(symbol: Symbol, resolvedSymbol: Symbol | undefined, expression: BinaryExpression | CallExpression, kind: AssignmentDeclarationKind) { + if (isCallExpression(expression)) { + if (resolvedSymbol) { + return getTypeOfSymbol(resolvedSymbol); // This shouldn't happen except under some hopefully forbidden merges of export assignments and object define assignments + } + const objectLitType = checkExpressionCached((expression as BindableObjectDefinePropertyCall).arguments[2]); + const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String); + if (valueType) { + return valueType; + } + const getFunc = getTypeOfPropertyOfType(objectLitType, "get" as __String); + if (getFunc) { + const getSig = getSingleCallSignature(getFunc); + if (getSig) { + return getReturnTypeOfSignature(getSig); + } + } + const setFunc = getTypeOfPropertyOfType(objectLitType, "set" as __String); + if (setFunc) { + const setSig = getSingleCallSignature(setFunc); + if (setSig) { + return getTypeOfFirstParameterOfSignature(setSig); + } + } + return anyType; + } + if (containsSameNamedThisProperty(expression.left, expression.right)) { + return anyType; + } + const isDirectExport = kind === AssignmentDeclarationKind.ExportsProperty && (isPropertyAccessExpression(expression.left) || isElementAccessExpression(expression.left)) && (isModuleExportsAccessExpression(expression.left.expression) || (isIdentifier(expression.left.expression) && isExportsIdentifier(expression.left.expression))); + const type = resolvedSymbol ? getTypeOfSymbol(resolvedSymbol) + : isDirectExport ? getRegularTypeOfLiteralType(checkExpressionCached(expression.right)) + : getWidenedLiteralType(checkExpressionCached(expression.right)); + if ( + type.flags & TypeFlags.Object && + kind === AssignmentDeclarationKind.ModuleExports && + symbol.escapedName === InternalSymbolName.ExportEquals + ) { + const exportedType = resolveStructuredTypeMembers(type as ObjectType); + const members = createSymbolTable(); + copyEntries(exportedType.members, members); + const initialSize = members.size; + if (resolvedSymbol && !resolvedSymbol.exports) { + resolvedSymbol.exports = createSymbolTable(); + } + (resolvedSymbol || symbol).exports!.forEach((s, name) => { + const exportedMember = members.get(name)!; + if (exportedMember && exportedMember !== s && !(s.flags & SymbolFlags.Alias)) { + if (s.flags & SymbolFlags.Value && exportedMember.flags & SymbolFlags.Value) { + // If the member has an additional value-like declaration, union the types from the two declarations, + // but issue an error if they occurred in two different files. The purpose is to support a JS file with + // a pattern like: + // + // module.exports = { a: true }; + // module.exports.a = 3; + // + // but we may have a JS file with `module.exports = { a: true }` along with a TypeScript module augmentation + // declaring an `export const a: number`. In that case, we issue a duplicate identifier error, because + // it's unclear what that's supposed to mean, so it's probably a mistake. + if (s.valueDeclaration && exportedMember.valueDeclaration && getSourceFileOfNode(s.valueDeclaration) !== getSourceFileOfNode(exportedMember.valueDeclaration)) { + const unescapedName = unescapeLeadingUnderscores(s.escapedName); + const exportedMemberName = tryCast(exportedMember.valueDeclaration, isNamedDeclaration)?.name || exportedMember.valueDeclaration; + addRelatedInfo( + error(s.valueDeclaration, Diagnostics.Duplicate_identifier_0, unescapedName), + createDiagnosticForNode(exportedMemberName, Diagnostics._0_was_also_declared_here, unescapedName), + ); + addRelatedInfo( + error(exportedMemberName, Diagnostics.Duplicate_identifier_0, unescapedName), + createDiagnosticForNode(s.valueDeclaration, Diagnostics._0_was_also_declared_here, unescapedName), + ); + } + const union = createSymbol(s.flags | exportedMember.flags, name); + union.links.type = getUnionType([getTypeOfSymbol(s), getTypeOfSymbol(exportedMember)]); + union.valueDeclaration = exportedMember.valueDeclaration; + union.declarations = concatenate(exportedMember.declarations, s.declarations); + members.set(name, union); + } + else { + members.set(name, mergeSymbol(s, exportedMember)); + } + } + else { + members.set(name, s); + } + }); + const result = createAnonymousType( + initialSize !== members.size ? undefined : exportedType.symbol, // Only set the type's symbol if it looks to be the same as the original type + members, + exportedType.callSignatures, + exportedType.constructSignatures, + exportedType.indexInfos, + ); + if (initialSize === members.size) { + if (type.aliasSymbol) { + result.aliasSymbol = type.aliasSymbol; + result.aliasTypeArguments = type.aliasTypeArguments; + } + if (getObjectFlags(type) & ObjectFlags.Reference) { + result.aliasSymbol = (type as TypeReference).symbol; + const args = getTypeArguments(type as TypeReference); + result.aliasTypeArguments = length(args) ? args : undefined; + } + } + result.objectFlags |= getPropagatingFlagsOfTypes([type]) | getObjectFlags(type) & (ObjectFlags.JSLiteral | ObjectFlags.ArrayLiteral | ObjectFlags.ObjectLiteral); + if (result.symbol && result.symbol.flags & SymbolFlags.Class && type === getDeclaredTypeOfClassOrInterface(result.symbol)) { + result.objectFlags |= ObjectFlags.IsClassInstanceClone; // Propagate the knowledge that this type is equivalent to the symbol's class instance type + } + return result; + } + if (isEmptyArrayLiteralType(type)) { + reportImplicitAny(expression, anyArrayType); + return anyArrayType; + } + return type; + } + + function containsSameNamedThisProperty(thisProperty: Expression, expression: Expression) { + return isPropertyAccessExpression(thisProperty) + && thisProperty.expression.kind === SyntaxKind.ThisKeyword + && forEachChildRecursively(expression, n => isMatchingReference(thisProperty, n)); + } + + function isDeclarationInConstructor(expression: Expression) { + const thisContainer = getThisContainer(expression, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + // Properties defined in a constructor (or base constructor, or javascript constructor function) don't get undefined added. + // Function expressions that are assigned to the prototype count as methods. + return thisContainer.kind === SyntaxKind.Constructor || + thisContainer.kind === SyntaxKind.FunctionDeclaration || + (thisContainer.kind === SyntaxKind.FunctionExpression && !isPrototypePropertyAssignment(thisContainer.parent)); + } + + function getConstructorDefinedThisAssignmentTypes(types: Type[], declarations: Declaration[]): Type[] | undefined { + Debug.assert(types.length === declarations.length); + return types.filter((_, i) => { + const declaration = declarations[i]; + const expression = isBinaryExpression(declaration) ? declaration : + isBinaryExpression(declaration.parent) ? declaration.parent : undefined; + return expression && isDeclarationInConstructor(expression); + }); + } + + // Return the type implied by a binding pattern element. This is the type of the initializer of the element if + // one is present. Otherwise, if the element is itself a binding pattern, it is the type implied by the binding + // pattern. Otherwise, it is the type any. + function getTypeFromBindingElement(element: BindingElement, includePatternInType?: boolean, reportErrors?: boolean): Type { + if (element.initializer) { + // The type implied by a binding pattern is independent of context, so we check the initializer with no + // contextual type or, if the element itself is a binding pattern, with the type implied by that binding + // pattern. + const contextualType = isBindingPattern(element.name) ? getTypeFromBindingPattern(element.name, /*includePatternInType*/ true, /*reportErrors*/ false) : unknownType; + return addOptionality(widenTypeInferredFromInitializer(element, checkDeclarationInitializer(element, reportErrors ? CheckMode.Normal : CheckMode.Contextual, contextualType))); + } + if (isBindingPattern(element.name)) { + return getTypeFromBindingPattern(element.name, includePatternInType, reportErrors); + } + if (reportErrors && !declarationBelongsToPrivateAmbientMember(element)) { + reportImplicitAny(element, anyType); + } + // When we're including the pattern in the type (an indication we're obtaining a contextual type), we + // use a non-inferrable any type. Inference will never directly infer this type, but it is possible + // to infer a type that contains it, e.g. for a binding pattern like [foo] or { foo }. In such cases, + // widening of the binding pattern type substitutes a regular any for the non-inferrable any. + return includePatternInType ? nonInferrableAnyType : anyType; + } + + // Return the type implied by an object binding pattern + function getTypeFromObjectBindingPattern(pattern: ObjectBindingPattern, includePatternInType: boolean, reportErrors: boolean): Type { + const members = createSymbolTable(); + let stringIndexInfo: IndexInfo | undefined; + let objectFlags = ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + forEach(pattern.elements, e => { + const name = e.propertyName || e.name as Identifier; + if (e.dotDotDotToken) { + stringIndexInfo = createIndexInfo(stringType, anyType, /*isReadonly*/ false); + return; + } + + const exprType = getLiteralTypeFromPropertyName(name); + if (!isTypeUsableAsPropertyName(exprType)) { + // do not include computed properties in the implied type + objectFlags |= ObjectFlags.ObjectLiteralPatternWithComputedProperties; + return; + } + const text = getPropertyNameFromType(exprType); + const flags = SymbolFlags.Property | (e.initializer ? SymbolFlags.Optional : 0); + const symbol = createSymbol(flags, text); + symbol.links.type = getTypeFromBindingElement(e, includePatternInType, reportErrors); + symbol.links.bindingElement = e; + members.set(symbol.escapedName, symbol); + }); + const result = createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, stringIndexInfo ? [stringIndexInfo] : emptyArray); + result.objectFlags |= objectFlags; + if (includePatternInType) { + result.pattern = pattern; + result.objectFlags |= ObjectFlags.ContainsObjectOrArrayLiteral; + } + return result; + } + + // Return the type implied by an array binding pattern + function getTypeFromArrayBindingPattern(pattern: BindingPattern, includePatternInType: boolean, reportErrors: boolean): Type { + const elements = pattern.elements; + const lastElement = lastOrUndefined(elements); + const restElement = lastElement && lastElement.kind === SyntaxKind.BindingElement && lastElement.dotDotDotToken ? lastElement : undefined; + if (elements.length === 0 || elements.length === 1 && restElement) { + return languageVersion >= ScriptTarget.ES2015 ? createIterableType(anyType) : anyArrayType; + } + const elementTypes = map(elements, e => isOmittedExpression(e) ? anyType : getTypeFromBindingElement(e, includePatternInType, reportErrors)); + const minLength = findLastIndex(elements, e => !(e === restElement || isOmittedExpression(e) || hasDefaultValue(e)), elements.length - 1) + 1; + const elementFlags = map(elements, (e, i) => e === restElement ? ElementFlags.Rest : i >= minLength ? ElementFlags.Optional : ElementFlags.Required); + let result = createTupleType(elementTypes, elementFlags) as TypeReference; + if (includePatternInType) { + result = cloneTypeReference(result); + result.pattern = pattern; + result.objectFlags |= ObjectFlags.ContainsObjectOrArrayLiteral; + } + return result; + } + + // Return the type implied by a binding pattern. This is the type implied purely by the binding pattern itself + // and without regard to its context (i.e. without regard any type annotation or initializer associated with the + // declaration in which the binding pattern is contained). For example, the implied type of [x, y] is [any, any] + // and the implied type of { x, y: z = 1 } is { x: any; y: number; }. The type implied by a binding pattern is + // used as the contextual type of an initializer associated with the binding pattern. Also, for a destructuring + // parameter with no type annotation or initializer, the type implied by the binding pattern becomes the type of + // the parameter. + function getTypeFromBindingPattern(pattern: BindingPattern, includePatternInType = false, reportErrors = false): Type { + return pattern.kind === SyntaxKind.ObjectBindingPattern + ? getTypeFromObjectBindingPattern(pattern, includePatternInType, reportErrors) + : getTypeFromArrayBindingPattern(pattern, includePatternInType, reportErrors); + } + + // Return the type associated with a variable, parameter, or property declaration. In the simple case this is the type + // specified in a type annotation or inferred from an initializer. However, in the case of a destructuring declaration it + // is a bit more involved. For example: + // + // var [x, s = ""] = [1, "one"]; + // + // Here, the array literal [1, "one"] is contextually typed by the type [any, string], which is the implied type of the + // binding pattern [x, s = ""]. Because the contextual type is a tuple type, the resulting type of [1, "one"] is the + // tuple type [number, string]. Thus, the type inferred for 'x' is number and the type inferred for 's' is string. + function getWidenedTypeForVariableLikeDeclaration(declaration: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement | JSDocPropertyLikeTag, reportErrors?: boolean): Type { + return widenTypeForVariableLikeDeclaration(getTypeForVariableLikeDeclaration(declaration, /*includeOptionality*/ true, CheckMode.Normal), declaration, reportErrors); + } + + function getTypeFromImportAttributes(node: ImportAttributes): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const symbol = createSymbol(SymbolFlags.ObjectLiteral, InternalSymbolName.ImportAttributes); + const members = createSymbolTable(); + forEach(node.elements, attr => { + const member = createSymbol(SymbolFlags.Property, getNameFromImportAttribute(attr)); + member.parent = symbol; + member.links.type = checkImportAttribute(attr); + member.links.target = member; + members.set(member.escapedName, member); + }); + const type = createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + type.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.NonInferrableType; + links.resolvedType = type; + } + return links.resolvedType; + } + + function isGlobalSymbolConstructor(node: Node) { + const symbol = getSymbolOfNode(node); + const globalSymbol = getGlobalESSymbolConstructorTypeSymbol(/*reportErrors*/ false); + return globalSymbol && symbol && symbol === globalSymbol; + } + + function widenTypeForVariableLikeDeclaration(type: Type | undefined, declaration: any, reportErrors?: boolean) { + if (type) { + // TODO: If back compat with pre-3.0/4.0 libs isn't required, remove the following SymbolConstructor special case transforming `symbol` into `unique symbol` + if (type.flags & TypeFlags.ESSymbol && isGlobalSymbolConstructor(declaration.parent)) { + type = getESSymbolLikeTypeForNode(declaration); + } + if (reportErrors) { + reportErrorsFromWidening(declaration, type); + } + + // always widen a 'unique symbol' type if the type was created for a different declaration. + if (type.flags & TypeFlags.UniqueESSymbol && (isBindingElement(declaration) || !declaration.type) && type.symbol !== getSymbolOfDeclaration(declaration)) { + type = esSymbolType; + } + + return getWidenedType(type); + } + + // Rest parameters default to type any[], other parameters default to type any + type = isParameter(declaration) && declaration.dotDotDotToken ? anyArrayType : anyType; + + // Report implicit any errors unless this is a private property within an ambient declaration + if (reportErrors) { + if (!declarationBelongsToPrivateAmbientMember(declaration)) { + reportImplicitAny(declaration, type); + } + } + return type; + } + + function declarationBelongsToPrivateAmbientMember(declaration: VariableLikeDeclaration) { + const root = getRootDeclaration(declaration); + const memberDeclaration = root.kind === SyntaxKind.Parameter ? root.parent : root; + return isPrivateWithinAmbient(memberDeclaration); + } + + function tryGetTypeFromEffectiveTypeNode(node: Node) { + const typeNode = getEffectiveTypeAnnotationNode(node); + if (typeNode) { + return getTypeFromTypeNode(typeNode); + } + } + + function isParameterOfContextSensitiveSignature(symbol: Symbol) { + let decl = symbol.valueDeclaration; + if (!decl) { + return false; + } + if (isBindingElement(decl)) { + decl = walkUpBindingElementsAndPatterns(decl); + } + if (isParameter(decl)) { + return isContextSensitiveFunctionOrObjectLiteralMethod(decl.parent); + } + return false; + } + + function getTypeOfVariableOrParameterOrProperty(symbol: Symbol, checkMode?: CheckMode): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + const type = getTypeOfVariableOrParameterOrPropertyWorker(symbol, checkMode); + // For a contextually typed parameter it is possible that a type has already + // been assigned (in assignTypeToParameterAndFixTypeParameters), and we want + // to preserve this type. In fact, we need to _prefer_ that type, but it won't + // be assigned until contextual typing is complete, so we need to defer in + // cases where contextual typing may take place. + if (!links.type && !isParameterOfContextSensitiveSignature(symbol) && !checkMode) { + links.type = type; + } + return type; + } + return links.type; + } + + function getTypeOfVariableOrParameterOrPropertyWorker(symbol: Symbol, checkMode?: CheckMode): Type { + // Handle prototype property + if (symbol.flags & SymbolFlags.Prototype) { + return getTypeOfPrototypeProperty(symbol); + } + // CommonsJS require and module both have type any. + if (symbol === requireSymbol) { + return anyType; + } + if (symbol.flags & SymbolFlags.ModuleExports && symbol.valueDeclaration) { + const fileSymbol = getSymbolOfDeclaration(getSourceFileOfNode(symbol.valueDeclaration)); + const result = createSymbol(fileSymbol.flags, "exports" as __String); + result.declarations = fileSymbol.declarations ? fileSymbol.declarations.slice() : []; + result.parent = symbol; + result.links.target = fileSymbol; + if (fileSymbol.valueDeclaration) result.valueDeclaration = fileSymbol.valueDeclaration; + if (fileSymbol.members) result.members = new Map(fileSymbol.members); + if (fileSymbol.exports) result.exports = new Map(fileSymbol.exports); + const members = createSymbolTable(); + members.set("exports" as __String, result); + return createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + } + Debug.assertIsDefined(symbol.valueDeclaration); + const declaration = symbol.valueDeclaration; + // Handle export default expressions + if (isSourceFile(declaration) && isJsonSourceFile(declaration)) { + if (!declaration.statements.length) { + return emptyObjectType; + } + return getWidenedType(getWidenedLiteralType(checkExpression(declaration.statements[0].expression))); + } + if (isAccessor(declaration)) { + // Binding of certain patterns in JS code will occasionally mark symbols as both properties + // and accessors. Here we dispatch to accessor resolution if needed. + return getTypeOfAccessors(symbol); + } + + // Handle variable, parameter or property + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` + if (symbol.flags & SymbolFlags.ValueModule && !(symbol.flags & SymbolFlags.Assignment)) { + return getTypeOfFuncClassEnumModule(symbol); + } + + // When trying to get the *contextual* type of a binding element, it's possible to fall in a loop and therefore + // end up in a circularity-like situation. This is not a true circularity so we should not report such an error. + // For example, here the looping could happen when trying to get the type of `a` (binding element): + // + // const { a, b = a } = { a: 0 } + // + if (isBindingElement(declaration) && checkMode === CheckMode.Contextual) { + return errorType; + } + return reportCircularityError(symbol); + } + let type: Type; + if (declaration.kind === SyntaxKind.ExportAssignment) { + type = widenTypeForVariableLikeDeclaration(tryGetTypeFromEffectiveTypeNode(declaration) || checkExpressionCached((declaration as ExportAssignment).expression), declaration); + } + else if ( + isBinaryExpression(declaration) || + (isInJSFile(declaration) && + (isCallExpression(declaration) || (isPropertyAccessExpression(declaration) || isBindableStaticElementAccessExpression(declaration)) && isBinaryExpression(declaration.parent))) + ) { + type = getWidenedTypeForAssignmentDeclaration(symbol); + } + else if ( + isPropertyAccessExpression(declaration) + || isElementAccessExpression(declaration) + || isIdentifier(declaration) + || isStringLiteralLike(declaration) + || isNumericLiteral(declaration) + || isClassDeclaration(declaration) + || isFunctionDeclaration(declaration) + || (isMethodDeclaration(declaration) && !isObjectLiteralMethod(declaration)) + || isMethodSignature(declaration) + || isSourceFile(declaration) + ) { + // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.Enum | SymbolFlags.ValueModule)) { + return getTypeOfFuncClassEnumModule(symbol); + } + type = isBinaryExpression(declaration.parent) ? + getWidenedTypeForAssignmentDeclaration(symbol) : + tryGetTypeFromEffectiveTypeNode(declaration) || anyType; + } + else if (isPropertyAssignment(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkPropertyAssignment(declaration); + } + else if (isJsxAttribute(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkJsxAttribute(declaration); + } + else if (isShorthandPropertyAssignment(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkExpressionForMutableLocation(declaration.name, CheckMode.Normal); + } + else if (isObjectLiteralMethod(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkObjectLiteralMethod(declaration, CheckMode.Normal); + } + else if ( + isParameter(declaration) + || isPropertyDeclaration(declaration) + || isPropertySignature(declaration) + || isVariableDeclaration(declaration) + || isBindingElement(declaration) + || isJSDocPropertyLikeTag(declaration) + ) { + type = getWidenedTypeForVariableLikeDeclaration(declaration, /*reportErrors*/ true); + } + // getTypeOfSymbol dispatches some JS merges incorrectly because their symbol flags are not mutually exclusive. + // Re-dispatch based on valueDeclaration.kind instead. + else if (isEnumDeclaration(declaration)) { + type = getTypeOfFuncClassEnumModule(symbol); + } + else if (isEnumMember(declaration)) { + type = getTypeOfEnumMember(symbol); + } + else { + return Debug.fail("Unhandled declaration kind! " + Debug.formatSyntaxKind(declaration.kind) + " for " + Debug.formatSymbol(symbol)); + } + + if (!popTypeResolution()) { + // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` + if (symbol.flags & SymbolFlags.ValueModule && !(symbol.flags & SymbolFlags.Assignment)) { + return getTypeOfFuncClassEnumModule(symbol); + } + + // When trying to get the *contextual* type of a binding element, it's possible to fall in a loop and therefore + // end up in a circularity-like situation. This is not a true circularity so we should not report such an error. + // For example, here the looping could happen when trying to get the type of `a` (binding element): + // + // const { a, b = a } = { a: 0 } + // + if (isBindingElement(declaration) && checkMode === CheckMode.Contextual) { + return type; + } + return reportCircularityError(symbol); + } + return type; + } + + function getAnnotatedAccessorTypeNode(accessor: AccessorDeclaration | PropertyDeclaration | undefined): TypeNode | undefined { + if (accessor) { + switch (accessor.kind) { + case SyntaxKind.GetAccessor: + const getterTypeAnnotation = getEffectiveReturnTypeNode(accessor); + return getterTypeAnnotation; + case SyntaxKind.SetAccessor: + const setterTypeAnnotation = getEffectiveSetAccessorTypeAnnotationNode(accessor); + return setterTypeAnnotation; + case SyntaxKind.PropertyDeclaration: + Debug.assert(hasAccessorModifier(accessor)); + const accessorTypeAnnotation = getEffectiveTypeAnnotationNode(accessor); + return accessorTypeAnnotation; + } + } + return undefined; + } + + function getAnnotatedAccessorType(accessor: AccessorDeclaration | PropertyDeclaration | undefined): Type | undefined { + const node = getAnnotatedAccessorTypeNode(accessor); + return node && getTypeFromTypeNode(node); + } + + function getAnnotatedAccessorThisParameter(accessor: AccessorDeclaration): Symbol | undefined { + const parameter = getAccessorThisParameter(accessor); + return parameter && parameter.symbol; + } + + function getThisTypeOfDeclaration(declaration: SignatureDeclaration): Type | undefined { + return getThisTypeOfSignature(getSignatureFromDeclaration(declaration)); + } + + function getTypeOfAccessors(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + return errorType; + } + const getter = getDeclarationOfKind(symbol, SyntaxKind.GetAccessor); + const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor); + const accessor = tryCast(getDeclarationOfKind(symbol, SyntaxKind.PropertyDeclaration), isAutoAccessorPropertyDeclaration); + + // We try to resolve a getter type annotation, a setter type annotation, or a getter function + // body return type inference, in that order. + let type = getter && isInJSFile(getter) && getTypeForDeclarationFromJSDocComment(getter) || + getAnnotatedAccessorType(getter) || + getAnnotatedAccessorType(setter) || + getAnnotatedAccessorType(accessor) || + getter && getter.body && getReturnTypeFromBody(getter) || + accessor && accessor.initializer && getWidenedTypeForVariableLikeDeclaration(accessor, /*reportErrors*/ true); + if (!type) { + if (setter && !isPrivateWithinAmbient(setter)) { + errorOrSuggestion(noImplicitAny, setter, Diagnostics.Property_0_implicitly_has_type_any_because_its_set_accessor_lacks_a_parameter_type_annotation, symbolToString(symbol)); + } + else if (getter && !isPrivateWithinAmbient(getter)) { + errorOrSuggestion(noImplicitAny, getter, Diagnostics.Property_0_implicitly_has_type_any_because_its_get_accessor_lacks_a_return_type_annotation, symbolToString(symbol)); + } + else if (accessor && !isPrivateWithinAmbient(accessor)) { + errorOrSuggestion(noImplicitAny, accessor, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), "any"); + } + type = anyType; + } + if (!popTypeResolution()) { + if (getAnnotatedAccessorTypeNode(getter)) { + error(getter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + else if (getAnnotatedAccessorTypeNode(setter)) { + error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + else if (getAnnotatedAccessorTypeNode(accessor)) { + error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + else if (getter && noImplicitAny) { + error(getter, Diagnostics._0_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions, symbolToString(symbol)); + } + type = anyType; + } + links.type ??= type; + } + return links.type; + } + + function getWriteTypeOfAccessors(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.writeType) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.WriteType)) { + return errorType; + } + + const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor) + ?? tryCast(getDeclarationOfKind(symbol, SyntaxKind.PropertyDeclaration), isAutoAccessorPropertyDeclaration); + let writeType = getAnnotatedAccessorType(setter); + if (!popTypeResolution()) { + if (getAnnotatedAccessorTypeNode(setter)) { + error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + writeType = anyType; + } + // Absent an explicit setter type annotation we use the read type of the accessor. + links.writeType ??= writeType || getTypeOfAccessors(symbol); + } + return links.writeType; + } + + function getBaseTypeVariableOfClass(symbol: Symbol) { + const baseConstructorType = getBaseConstructorTypeOfClass(getDeclaredTypeOfClassOrInterface(symbol)); + return baseConstructorType.flags & TypeFlags.TypeVariable ? baseConstructorType : + baseConstructorType.flags & TypeFlags.Intersection ? find((baseConstructorType as IntersectionType).types, t => !!(t.flags & TypeFlags.TypeVariable)) : + undefined; + } + + function getTypeOfFuncClassEnumModule(symbol: Symbol): Type { + let links = getSymbolLinks(symbol); + const originalLinks = links; + if (!links.type) { + const expando = symbol.valueDeclaration && getSymbolOfExpando(symbol.valueDeclaration, /*allowDeclaration*/ false); + if (expando) { + const merged = mergeJSSymbols(symbol, expando); + if (merged) { + // note:we overwrite links because we just cloned the symbol + symbol = merged; + links = merged.links; + } + } + originalLinks.type = links.type = getTypeOfFuncClassEnumModuleWorker(symbol); + } + return links.type; + } + + function getTypeOfFuncClassEnumModuleWorker(symbol: Symbol): Type { + const declaration = symbol.valueDeclaration; + if (symbol.flags & SymbolFlags.Module && isShorthandAmbientModuleSymbol(symbol)) { + return anyType; + } + else if ( + declaration && (declaration.kind === SyntaxKind.BinaryExpression || + isAccessExpression(declaration) && + declaration.parent.kind === SyntaxKind.BinaryExpression) + ) { + return getWidenedTypeForAssignmentDeclaration(symbol); + } + else if (symbol.flags & SymbolFlags.ValueModule && declaration && isSourceFile(declaration) && declaration.commonJsModuleIndicator) { + const resolvedModule = resolveExternalModuleSymbol(symbol); + if (resolvedModule !== symbol) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + return errorType; + } + const exportEquals = getMergedSymbol(symbol.exports!.get(InternalSymbolName.ExportEquals)!); + const type = getWidenedTypeForAssignmentDeclaration(exportEquals, exportEquals === resolvedModule ? undefined : resolvedModule); + if (!popTypeResolution()) { + return reportCircularityError(symbol); + } + return type; + } + } + const type = createObjectType(ObjectFlags.Anonymous, symbol); + if (symbol.flags & SymbolFlags.Class) { + const baseTypeVariable = getBaseTypeVariableOfClass(symbol); + return baseTypeVariable ? getIntersectionType([type, baseTypeVariable]) : type; + } + else { + return strictNullChecks && symbol.flags & SymbolFlags.Optional ? getOptionalType(type, /*isProperty*/ true) : type; + } + } + + function getTypeOfEnumMember(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.type || (links.type = getDeclaredTypeOfEnumMember(symbol)); + } + + function getTypeOfAlias(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + return errorType; + } + const targetSymbol = resolveAlias(symbol); + const exportSymbol = symbol.declarations && getTargetOfAliasDeclaration(getDeclarationOfAliasSymbol(symbol)!, /*dontRecursivelyResolve*/ true); + const declaredType = firstDefined(exportSymbol?.declarations, d => isExportAssignment(d) ? tryGetTypeFromEffectiveTypeNode(d) : undefined); + + // It only makes sense to get the type of a value symbol. If the result of resolving + // the alias is not a value, then it has no type. To get the type associated with a + // type symbol, call getDeclaredTypeOfSymbol. + // This check is important because without it, a call to getTypeOfSymbol could end + // up recursively calling getTypeOfAlias, causing a stack overflow. + links.type ??= exportSymbol?.declarations && isDuplicatedCommonJSExport(exportSymbol.declarations) && symbol.declarations!.length ? getFlowTypeFromCommonJSExport(exportSymbol) + : isDuplicatedCommonJSExport(symbol.declarations) ? autoType + : declaredType ? declaredType + : getSymbolFlags(targetSymbol) & SymbolFlags.Value ? getTypeOfSymbol(targetSymbol) + : errorType; + + if (!popTypeResolution()) { + reportCircularityError(exportSymbol ?? symbol); + return links.type ??= errorType; + } + } + return links.type; + } + + function getTypeOfInstantiatedSymbol(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.type || (links.type = instantiateType(getTypeOfSymbol(links.target!), links.mapper)); + } + + function getWriteTypeOfInstantiatedSymbol(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.writeType || (links.writeType = instantiateType(getWriteTypeOfSymbol(links.target!), links.mapper)); + } + + function reportCircularityError(symbol: Symbol) { + const declaration = symbol.valueDeclaration; + // Check if variable has type annotation that circularly references the variable itself + if (declaration) { + if (getEffectiveTypeAnnotationNode(declaration)) { + error(symbol.valueDeclaration, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + return errorType; + } + // Check if variable has initializer that circularly references the variable itself + if (noImplicitAny && (declaration.kind !== SyntaxKind.Parameter || (declaration as HasInitializer).initializer)) { + error(symbol.valueDeclaration, Diagnostics._0_implicitly_has_type_any_because_it_does_not_have_a_type_annotation_and_is_referenced_directly_or_indirectly_in_its_own_initializer, symbolToString(symbol)); + } + } + else if (symbol.flags & SymbolFlags.Alias) { + const node = getDeclarationOfAliasSymbol(symbol); + if (node) { + error(node, Diagnostics.Circular_definition_of_import_alias_0, symbolToString(symbol)); + } + } + // Circularities could also result from parameters in function expressions that end up + // having themselves as contextual types following type argument inference. In those cases + // we have already reported an implicit any error so we don't report anything here. + return anyType; + } + + function getTypeOfSymbolWithDeferredType(symbol: Symbol) { + const links = getSymbolLinks(symbol); + if (!links.type) { + Debug.assertIsDefined(links.deferralParent); + Debug.assertIsDefined(links.deferralConstituents); + links.type = links.deferralParent.flags & TypeFlags.Union ? getUnionType(links.deferralConstituents) : getIntersectionType(links.deferralConstituents); + } + return links.type; + } + + function getWriteTypeOfSymbolWithDeferredType(symbol: Symbol): Type | undefined { + const links = getSymbolLinks(symbol); + if (!links.writeType && links.deferralWriteConstituents) { + Debug.assertIsDefined(links.deferralParent); + Debug.assertIsDefined(links.deferralConstituents); + links.writeType = links.deferralParent.flags & TypeFlags.Union ? getUnionType(links.deferralWriteConstituents) : getIntersectionType(links.deferralWriteConstituents); + } + return links.writeType; + } + + /** + * Distinct write types come only from set accessors, but synthetic union and intersection + * properties deriving from set accessors will either pre-compute or defer the union or + * intersection of the writeTypes of their constituents. + */ + function getWriteTypeOfSymbol(symbol: Symbol): Type { + const checkFlags = getCheckFlags(symbol); + if (symbol.flags & SymbolFlags.Property) { + return checkFlags & CheckFlags.SyntheticProperty ? + checkFlags & CheckFlags.DeferredType ? + getWriteTypeOfSymbolWithDeferredType(symbol) || getTypeOfSymbolWithDeferredType(symbol) : + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.SyntheticProperty + (symbol as TransientSymbol).links.writeType || (symbol as TransientSymbol).links.type! : + removeMissingType(getTypeOfSymbol(symbol), !!(symbol.flags & SymbolFlags.Optional)); + } + if (symbol.flags & SymbolFlags.Accessor) { + return checkFlags & CheckFlags.Instantiated ? + getWriteTypeOfInstantiatedSymbol(symbol) : + getWriteTypeOfAccessors(symbol); + } + return getTypeOfSymbol(symbol); + } + + function getTypeOfSymbol(symbol: Symbol, checkMode?: CheckMode): Type { + const checkFlags = getCheckFlags(symbol); + if (checkFlags & CheckFlags.DeferredType) { + return getTypeOfSymbolWithDeferredType(symbol); + } + if (checkFlags & CheckFlags.Instantiated) { + return getTypeOfInstantiatedSymbol(symbol); + } + if (checkFlags & CheckFlags.Mapped) { + return getTypeOfMappedSymbol(symbol as MappedSymbol); + } + if (checkFlags & CheckFlags.ReverseMapped) { + return getTypeOfReverseMappedSymbol(symbol as ReverseMappedSymbol); + } + if (symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property)) { + return getTypeOfVariableOrParameterOrProperty(symbol, checkMode); + } + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.Enum | SymbolFlags.ValueModule)) { + return getTypeOfFuncClassEnumModule(symbol); + } + if (symbol.flags & SymbolFlags.EnumMember) { + return getTypeOfEnumMember(symbol); + } + if (symbol.flags & SymbolFlags.Accessor) { + return getTypeOfAccessors(symbol); + } + if (symbol.flags & SymbolFlags.Alias) { + return getTypeOfAlias(symbol); + } + return errorType; + } + + function getNonMissingTypeOfSymbol(symbol: Symbol) { + return removeMissingType(getTypeOfSymbol(symbol), !!(symbol.flags & SymbolFlags.Optional)); + } + + function isReferenceToType(type: Type, target: Type) { + return type !== undefined + && target !== undefined + && (getObjectFlags(type) & ObjectFlags.Reference) !== 0 + && (type as TypeReference).target === target; + } + + function getTargetType(type: Type): Type { + return getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).target : type; + } + + // TODO: GH#18217 If `checkBase` is undefined, we should not call this because this will always return false. + function hasBaseType(type: Type, checkBase: Type | undefined) { + return check(type); + function check(type: Type): boolean { + if (getObjectFlags(type) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference)) { + const target = getTargetType(type) as InterfaceType; + return target === checkBase || some(getBaseTypes(target), check); + } + else if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, check); + } + return false; + } + } + + // Appends the type parameters given by a list of declarations to a set of type parameters and returns the resulting set. + // The function allocates a new array if the input type parameter set is undefined, but otherwise it modifies the set + // in-place and returns the same array. + function appendTypeParameters(typeParameters: TypeParameter[] | undefined, declarations: readonly TypeParameterDeclaration[]): TypeParameter[] | undefined { + for (const declaration of declarations) { + typeParameters = appendIfUnique(typeParameters, getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(declaration))); + } + return typeParameters; + } + + // Return the outer type parameters of a node or undefined if the node has no outer type parameters. + function getOuterTypeParameters(node: Node, includeThisTypes?: boolean): TypeParameter[] | undefined { + while (true) { + node = node.parent; // TODO: GH#18217 Use SourceFile kind check instead + if (node && isBinaryExpression(node)) { + // prototype assignments get the outer type parameters of their constructor function + const assignmentKind = getAssignmentDeclarationKind(node); + if (assignmentKind === AssignmentDeclarationKind.Prototype || assignmentKind === AssignmentDeclarationKind.PrototypeProperty) { + const symbol = getSymbolOfDeclaration(node.left as BindableStaticNameExpression | PropertyAssignment); + if (symbol && symbol.parent && !findAncestor(symbol.parent.valueDeclaration, d => node === d)) { + node = symbol.parent.valueDeclaration!; + } + } + } + if (!node) { + return undefined; + } + switch (node.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.CallSignature: + case SyntaxKind.ConstructSignature: + case SyntaxKind.MethodSignature: + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.JSDocFunctionType: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.JSDocTemplateTag: + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocEnumTag: + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.MappedType: + case SyntaxKind.ConditionalType: { + const outerTypeParameters = getOuterTypeParameters(node, includeThisTypes); + if (node.kind === SyntaxKind.MappedType) { + return append(outerTypeParameters, getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration((node as MappedTypeNode).typeParameter))); + } + else if (node.kind === SyntaxKind.ConditionalType) { + return concatenate(outerTypeParameters, getInferTypeParameters(node as ConditionalTypeNode)); + } + const outerAndOwnTypeParameters = appendTypeParameters(outerTypeParameters, getEffectiveTypeParameterDeclarations(node as DeclarationWithTypeParameters)); + const thisType = includeThisTypes && + (node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression || node.kind === SyntaxKind.InterfaceDeclaration || isJSConstructor(node)) && + getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node as ClassLikeDeclaration | InterfaceDeclaration)).thisType; + return thisType ? append(outerAndOwnTypeParameters, thisType) : outerAndOwnTypeParameters; + } + case SyntaxKind.JSDocParameterTag: + const paramSymbol = getParameterSymbolFromJSDoc(node as JSDocParameterTag); + if (paramSymbol) { + node = paramSymbol.valueDeclaration!; + } + break; + case SyntaxKind.JSDoc: { + const outerTypeParameters = getOuterTypeParameters(node, includeThisTypes); + return (node as JSDoc).tags + ? appendTypeParameters(outerTypeParameters, flatMap((node as JSDoc).tags, t => isJSDocTemplateTag(t) ? t.typeParameters : undefined)) + : outerTypeParameters; + } + } + } + } + + // The outer type parameters are those defined by enclosing generic classes, methods, or functions. + function getOuterTypeParametersOfClassOrInterface(symbol: Symbol): TypeParameter[] | undefined { + const declaration = (symbol.flags & SymbolFlags.Class || symbol.flags & SymbolFlags.Function) + ? symbol.valueDeclaration + : symbol.declarations?.find(decl => { + if (decl.kind === SyntaxKind.InterfaceDeclaration) { + return true; + } + if (decl.kind !== SyntaxKind.VariableDeclaration) { + return false; + } + const initializer = (decl as VariableDeclaration).initializer; + return !!initializer && (initializer.kind === SyntaxKind.FunctionExpression || initializer.kind === SyntaxKind.ArrowFunction); + })!; + Debug.assert(!!declaration, "Class was missing valueDeclaration -OR- non-class had no interface declarations"); + return getOuterTypeParameters(declaration); + } + + // The local type parameters are the combined set of type parameters from all declarations of the class, + // interface, or type alias. + function getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol: Symbol): TypeParameter[] | undefined { + if (!symbol.declarations) { + return; + } + let result: TypeParameter[] | undefined; + for (const node of symbol.declarations) { + if ( + node.kind === SyntaxKind.InterfaceDeclaration || + node.kind === SyntaxKind.ClassDeclaration || + node.kind === SyntaxKind.ClassExpression || + isJSConstructor(node) || + isTypeAlias(node) + ) { + const declaration = node as InterfaceDeclaration | TypeAliasDeclaration | JSDocTypedefTag | JSDocCallbackTag; + result = appendTypeParameters(result, getEffectiveTypeParameterDeclarations(declaration)); + } + } + return result; + } + + // The full set of type parameters for a generic class or interface type consists of its outer type parameters plus + // its locally declared type parameters. + function getTypeParametersOfClassOrInterface(symbol: Symbol): TypeParameter[] | undefined { + return concatenate(getOuterTypeParametersOfClassOrInterface(symbol), getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol)); + } + + // A type is a mixin constructor if it has a single construct signature taking no type parameters and a single + // rest parameter of type any[]. + function isMixinConstructorType(type: Type) { + const signatures = getSignaturesOfType(type, SignatureKind.Construct); + if (signatures.length === 1) { + const s = signatures[0]; + if (!s.typeParameters && s.parameters.length === 1 && signatureHasRestParameter(s)) { + const paramType = getTypeOfParameter(s.parameters[0]); + return isTypeAny(paramType) || getElementTypeOfArrayType(paramType) === anyType; + } + } + return false; + } + + function isConstructorType(type: Type): boolean { + if (getSignaturesOfType(type, SignatureKind.Construct).length > 0) { + return true; + } + if (type.flags & TypeFlags.TypeVariable) { + const constraint = getBaseConstraintOfType(type); + return !!constraint && isMixinConstructorType(constraint); + } + return false; + } + + function getBaseTypeNodeOfClass(type: InterfaceType): ExpressionWithTypeArguments | undefined { + const decl = getClassLikeDeclarationOfSymbol(type.symbol); + return decl && getEffectiveBaseTypeNode(decl); + } + + function getConstructorsForTypeArguments(type: Type, typeArgumentNodes: readonly TypeNode[] | undefined, location: Node): readonly Signature[] { + const typeArgCount = length(typeArgumentNodes); + const isJavascript = isInJSFile(location); + return filter(getSignaturesOfType(type, SignatureKind.Construct), sig => (isJavascript || typeArgCount >= getMinTypeArgumentCount(sig.typeParameters)) && typeArgCount <= length(sig.typeParameters)); + } + + function getInstantiatedConstructorsForTypeArguments(type: Type, typeArgumentNodes: readonly TypeNode[] | undefined, location: Node): readonly Signature[] { + const signatures = getConstructorsForTypeArguments(type, typeArgumentNodes, location); + const typeArguments = map(typeArgumentNodes, getTypeFromTypeNode); + return sameMap(signatures, sig => some(sig.typeParameters) ? getSignatureInstantiation(sig, typeArguments, isInJSFile(location)) : sig); + } + + /** + * The base constructor of a class can resolve to + * * undefinedType if the class has no extends clause, + * * errorType if an error occurred during resolution of the extends expression, + * * nullType if the extends expression is the null value, + * * anyType if the extends expression has type any, or + * * an object type with at least one construct signature. + */ + function getBaseConstructorTypeOfClass(type: InterfaceType): Type { + if (!type.resolvedBaseConstructorType) { + const decl = getClassLikeDeclarationOfSymbol(type.symbol); + const extended = decl && getEffectiveBaseTypeNode(decl); + const baseTypeNode = getBaseTypeNodeOfClass(type); + if (!baseTypeNode) { + return type.resolvedBaseConstructorType = undefinedType; + } + if (!pushTypeResolution(type, TypeSystemPropertyName.ResolvedBaseConstructorType)) { + return errorType; + } + const baseConstructorType = checkExpression(baseTypeNode.expression); + if (extended && baseTypeNode !== extended) { + Debug.assert(!extended.typeArguments); // Because this is in a JS file, and baseTypeNode is in an @extends tag + checkExpression(extended.expression); + } + if (baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection)) { + // Resolving the members of a class requires us to resolve the base class of that class. + // We force resolution here such that we catch circularities now. + resolveStructuredTypeMembers(baseConstructorType as ObjectType); + } + if (!popTypeResolution()) { + error(type.symbol.valueDeclaration, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_base_expression, symbolToString(type.symbol)); + return type.resolvedBaseConstructorType ??= errorType; + } + if (!(baseConstructorType.flags & TypeFlags.Any) && baseConstructorType !== nullWideningType && !isConstructorType(baseConstructorType)) { + const err = error(baseTypeNode.expression, Diagnostics.Type_0_is_not_a_constructor_function_type, typeToString(baseConstructorType)); + if (baseConstructorType.flags & TypeFlags.TypeParameter) { + const constraint = getConstraintFromTypeParameter(baseConstructorType); + let ctorReturn: Type = unknownType; + if (constraint) { + const ctorSig = getSignaturesOfType(constraint, SignatureKind.Construct); + if (ctorSig[0]) { + ctorReturn = getReturnTypeOfSignature(ctorSig[0]); + } + } + if (baseConstructorType.symbol.declarations) { + addRelatedInfo(err, createDiagnosticForNode(baseConstructorType.symbol.declarations[0], Diagnostics.Did_you_mean_for_0_to_be_constrained_to_type_new_args_Colon_any_1, symbolToString(baseConstructorType.symbol), typeToString(ctorReturn))); + } + } + return type.resolvedBaseConstructorType ??= errorType; + } + type.resolvedBaseConstructorType ??= baseConstructorType; + } + return type.resolvedBaseConstructorType; + } + + function getImplementsTypes(type: InterfaceType): BaseType[] { + let resolvedImplementsTypes: BaseType[] = emptyArray; + if (type.symbol.declarations) { + for (const declaration of type.symbol.declarations) { + const implementsTypeNodes = getEffectiveImplementsTypeNodes(declaration as ClassLikeDeclaration); + if (!implementsTypeNodes) continue; + for (const node of implementsTypeNodes) { + const implementsType = getTypeFromTypeNode(node); + if (!isErrorType(implementsType)) { + if (resolvedImplementsTypes === emptyArray) { + resolvedImplementsTypes = [implementsType as ObjectType]; + } + else { + resolvedImplementsTypes.push(implementsType); + } + } + } + } + } + return resolvedImplementsTypes; + } + + function reportCircularBaseType(node: Node, type: Type) { + error(node, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType)); + } + + function getBaseTypes(type: InterfaceType): BaseType[] { + if (!type.baseTypesResolved) { + if (pushTypeResolution(type, TypeSystemPropertyName.ResolvedBaseTypes)) { + if (type.objectFlags & ObjectFlags.Tuple) { + type.resolvedBaseTypes = [getTupleBaseType(type as TupleType)]; + } + else if (type.symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { + if (type.symbol.flags & SymbolFlags.Class) { + resolveBaseTypesOfClass(type); + } + if (type.symbol.flags & SymbolFlags.Interface) { + resolveBaseTypesOfInterface(type); + } + } + else { + Debug.fail("type must be class or interface"); + } + if (!popTypeResolution() && type.symbol.declarations) { + for (const declaration of type.symbol.declarations) { + if (declaration.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.InterfaceDeclaration) { + reportCircularBaseType(declaration, type); + } + } + } + } + type.baseTypesResolved = true; + } + return type.resolvedBaseTypes; + } + + function getTupleBaseType(type: TupleType) { + const elementTypes = sameMap(type.typeParameters, (t, i) => type.elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t); + return createArrayType(getUnionType(elementTypes || emptyArray), type.readonly); + } + + function resolveBaseTypesOfClass(type: InterfaceType) { + type.resolvedBaseTypes = resolvingEmptyArray; + const baseConstructorType = getApparentType(getBaseConstructorTypeOfClass(type)); + if (!(baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Any))) { + return type.resolvedBaseTypes = emptyArray; + } + const baseTypeNode = getBaseTypeNodeOfClass(type)!; + let baseType: Type; + const originalBaseType = baseConstructorType.symbol ? getDeclaredTypeOfSymbol(baseConstructorType.symbol) : undefined; + if ( + baseConstructorType.symbol && baseConstructorType.symbol.flags & SymbolFlags.Class && + areAllOuterTypeParametersApplied(originalBaseType!) + ) { + // When base constructor type is a class with no captured type arguments we know that the constructors all have the same type parameters as the + // class and all return the instance type of the class. There is no need for further checks and we can apply the + // type arguments in the same manner as a type reference to get the same error reporting experience. + baseType = getTypeFromClassOrInterfaceReference(baseTypeNode, baseConstructorType.symbol); + } + else if (baseConstructorType.flags & TypeFlags.Any) { + baseType = baseConstructorType; + } + else { + // The class derives from a "class-like" constructor function, check that we have at least one construct signature + // with a matching number of type parameters and use the return type of the first instantiated signature. Elsewhere + // we check that all instantiated signatures return the same type. + const constructors = getInstantiatedConstructorsForTypeArguments(baseConstructorType, baseTypeNode.typeArguments, baseTypeNode); + if (!constructors.length) { + error(baseTypeNode.expression, Diagnostics.No_base_constructor_has_the_specified_number_of_type_arguments); + return type.resolvedBaseTypes = emptyArray; + } + baseType = getReturnTypeOfSignature(constructors[0]); + } + + if (isErrorType(baseType)) { + return type.resolvedBaseTypes = emptyArray; + } + const reducedBaseType = getReducedType(baseType); + if (!isValidBaseType(reducedBaseType)) { + const elaboration = elaborateNeverIntersection(/*errorInfo*/ undefined, baseType); + const diagnostic = chainDiagnosticMessages(elaboration, Diagnostics.Base_constructor_return_type_0_is_not_an_object_type_or_intersection_of_object_types_with_statically_known_members, typeToString(reducedBaseType)); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(baseTypeNode.expression), baseTypeNode.expression, diagnostic)); + return type.resolvedBaseTypes = emptyArray; + } + if (type === reducedBaseType || hasBaseType(reducedBaseType, type)) { + error(type.symbol.valueDeclaration, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType)); + return type.resolvedBaseTypes = emptyArray; + } + if (type.resolvedBaseTypes === resolvingEmptyArray) { + // Circular reference, likely through instantiation of default parameters + // (otherwise there'd be an error from hasBaseType) - this is fine, but `.members` should be reset + // as `getIndexedAccessType` via `instantiateType` via `getTypeFromClassOrInterfaceReference` forces a + // partial instantiation of the members without the base types fully resolved + type.members = undefined; + } + return type.resolvedBaseTypes = [reducedBaseType]; + } + + function areAllOuterTypeParametersApplied(type: Type): boolean { // TODO: GH#18217 Shouldn't this take an InterfaceType? + // An unapplied type parameter has its symbol still the same as the matching argument symbol. + // Since parameters are applied outer-to-inner, only the last outer parameter needs to be checked. + const outerTypeParameters = (type as InterfaceType).outerTypeParameters; + if (outerTypeParameters) { + const last = outerTypeParameters.length - 1; + const typeArguments = getTypeArguments(type as TypeReference); + return outerTypeParameters[last].symbol !== typeArguments[last].symbol; + } + return true; + } + + // A valid base type is `any`, an object type or intersection of object types. + function isValidBaseType(type: Type): type is BaseType { + if (type.flags & TypeFlags.TypeParameter) { + const constraint = getBaseConstraintOfType(type); + if (constraint) { + return isValidBaseType(constraint); + } + } + // TODO: Given that we allow type parmeters here now, is this `!isGenericMappedType(type)` check really needed? + // There's no reason a `T` should be allowed while a `Readonly` should not. + return !!(type.flags & (TypeFlags.Object | TypeFlags.NonPrimitive | TypeFlags.Any) && !isGenericMappedType(type) || + type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, isValidBaseType)); + } + + function resolveBaseTypesOfInterface(type: InterfaceType): void { + type.resolvedBaseTypes = type.resolvedBaseTypes || emptyArray; + if (type.symbol.declarations) { + for (const declaration of type.symbol.declarations) { + if (declaration.kind === SyntaxKind.InterfaceDeclaration && getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration)) { + for (const node of getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration)!) { + const baseType = getReducedType(getTypeFromTypeNode(node)); + if (!isErrorType(baseType)) { + if (isValidBaseType(baseType)) { + if (type !== baseType && !hasBaseType(baseType, type)) { + if (type.resolvedBaseTypes === emptyArray) { + type.resolvedBaseTypes = [baseType as ObjectType]; + } + else { + type.resolvedBaseTypes.push(baseType); + } + } + else { + reportCircularBaseType(declaration, type); + } + } + else { + error(node, Diagnostics.An_interface_can_only_extend_an_object_type_or_intersection_of_object_types_with_statically_known_members); + } + } + } + } + } + } + } + + /** + * Returns true if the interface given by the symbol is free of "this" references. + * + * Specifically, the result is true if the interface itself contains no references + * to "this" in its body, if all base types are interfaces, + * and if none of the base interfaces have a "this" type. + */ + function isThislessInterface(symbol: Symbol): boolean { + if (!symbol.declarations) { + return true; + } + for (const declaration of symbol.declarations) { + if (declaration.kind === SyntaxKind.InterfaceDeclaration) { + if (declaration.flags & NodeFlags.ContainsThis) { + return false; + } + const baseTypeNodes = getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration); + if (baseTypeNodes) { + for (const node of baseTypeNodes) { + if (isEntityNameExpression(node.expression)) { + const baseSymbol = resolveEntityName(node.expression, SymbolFlags.Type, /*ignoreErrors*/ true); + if (!baseSymbol || !(baseSymbol.flags & SymbolFlags.Interface) || getDeclaredTypeOfClassOrInterface(baseSymbol).thisType) { + return false; + } + } + } + } + } + } + return true; + } + + function getDeclaredTypeOfClassOrInterface(symbol: Symbol): InterfaceType { + let links = getSymbolLinks(symbol); + const originalLinks = links; + if (!links.declaredType) { + const kind = symbol.flags & SymbolFlags.Class ? ObjectFlags.Class : ObjectFlags.Interface; + const merged = mergeJSSymbols(symbol, symbol.valueDeclaration && getAssignedClassSymbol(symbol.valueDeclaration)); + if (merged) { + // note:we overwrite links because we just cloned the symbol + symbol = merged; + links = merged.links; + } + + const type = originalLinks.declaredType = links.declaredType = createObjectType(kind, symbol) as InterfaceType; + const outerTypeParameters = getOuterTypeParametersOfClassOrInterface(symbol); + const localTypeParameters = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + // A class or interface is generic if it has type parameters or a "this" type. We always give classes a "this" type + // because it is not feasible to analyze all members to determine if the "this" type escapes the class (in particular, + // property types inferred from initializers and method return types inferred from return statements are very hard + // to exhaustively analyze). We give interfaces a "this" type if we can't definitely determine that they are free of + // "this" references. + if (outerTypeParameters || localTypeParameters || kind === ObjectFlags.Class || !isThislessInterface(symbol)) { + type.objectFlags |= ObjectFlags.Reference; + type.typeParameters = concatenate(outerTypeParameters, localTypeParameters); + type.outerTypeParameters = outerTypeParameters; + type.localTypeParameters = localTypeParameters; + (type as GenericType).instantiations = new Map(); + (type as GenericType).instantiations.set(getTypeListId(type.typeParameters), type as GenericType); + (type as GenericType).target = type as GenericType; + (type as GenericType).resolvedTypeArguments = type.typeParameters; + type.thisType = createTypeParameter(symbol); + type.thisType.isThisType = true; + type.thisType.constraint = type; + } + } + return links.declaredType as InterfaceType; + } + + function getDeclaredTypeOfTypeAlias(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.declaredType) { + // Note that we use the links object as the target here because the symbol object is used as the unique + // identity for resolution of the 'type' property in SymbolLinks. + if (!pushTypeResolution(symbol, TypeSystemPropertyName.DeclaredType)) { + return errorType; + } + + const declaration = Debug.checkDefined(symbol.declarations?.find(isTypeAlias), "Type alias symbol with no valid declaration found"); + const typeNode = isJSDocTypeAlias(declaration) ? declaration.typeExpression : declaration.type; + // If typeNode is missing, we will error in checkJSDocTypedefTag. + let type = typeNode ? getTypeFromTypeNode(typeNode) : errorType; + + if (popTypeResolution()) { + const typeParameters = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + if (typeParameters) { + // Initialize the instantiation cache for generic type aliases. The declared type corresponds to + // an instantiation of the type alias with the type parameters supplied as type arguments. + links.typeParameters = typeParameters; + links.instantiations = new Map(); + links.instantiations.set(getTypeListId(typeParameters), type); + } + } + else { + type = errorType; + if (declaration.kind === SyntaxKind.JSDocEnumTag) { + error(declaration.typeExpression.type, Diagnostics.Type_alias_0_circularly_references_itself, symbolToString(symbol)); + } + else { + error(isNamedDeclaration(declaration) ? declaration.name || declaration : declaration, Diagnostics.Type_alias_0_circularly_references_itself, symbolToString(symbol)); + } + } + links.declaredType ??= type; + } + return links.declaredType; + } + + function getBaseTypeOfEnumLikeType(type: Type) { + return type.flags & TypeFlags.EnumLike && type.symbol.flags & SymbolFlags.EnumMember ? getDeclaredTypeOfSymbol(getParentOfSymbol(type.symbol)!) : type; + } + + function getDeclaredTypeOfEnum(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.declaredType) { + const memberTypeList: Type[] = []; + if (symbol.declarations) { + for (const declaration of symbol.declarations) { + if (declaration.kind === SyntaxKind.EnumDeclaration) { + for (const member of (declaration as EnumDeclaration).members) { + if (hasBindableName(member)) { + const memberSymbol = getSymbolOfDeclaration(member); + const value = getEnumMemberValue(member).value; + const memberType = getFreshTypeOfLiteralType( + value !== undefined ? + getEnumLiteralType(value, getSymbolId(symbol), memberSymbol) : + createComputedEnumType(memberSymbol), + ); + getSymbolLinks(memberSymbol).declaredType = memberType; + memberTypeList.push(getRegularTypeOfLiteralType(memberType)); + } + } + } + } + } + const enumType = memberTypeList.length ? + getUnionType(memberTypeList, UnionReduction.Literal, symbol, /*aliasTypeArguments*/ undefined) : + createComputedEnumType(symbol); + if (enumType.flags & TypeFlags.Union) { + enumType.flags |= TypeFlags.EnumLiteral; + enumType.symbol = symbol; + } + links.declaredType = enumType; + } + return links.declaredType; + } + + function createComputedEnumType(symbol: Symbol) { + const regularType = createTypeWithSymbol(TypeFlags.Enum, symbol) as EnumType; + const freshType = createTypeWithSymbol(TypeFlags.Enum, symbol) as EnumType; + regularType.regularType = regularType; + regularType.freshType = freshType; + freshType.regularType = regularType; + freshType.freshType = freshType; + return regularType; + } + + function getDeclaredTypeOfEnumMember(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.declaredType) { + const enumType = getDeclaredTypeOfEnum(getParentOfSymbol(symbol)!); + if (!links.declaredType) { + links.declaredType = enumType; + } + } + return links.declaredType; + } + + function getDeclaredTypeOfTypeParameter(symbol: Symbol): TypeParameter { + const links = getSymbolLinks(symbol); + return links.declaredType || (links.declaredType = createTypeParameter(symbol)); + } + + function getDeclaredTypeOfAlias(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.declaredType || (links.declaredType = getDeclaredTypeOfSymbol(resolveAlias(symbol))); + } + + function getDeclaredTypeOfSymbol(symbol: Symbol): Type { + return tryGetDeclaredTypeOfSymbol(symbol) || errorType; + } + + function tryGetDeclaredTypeOfSymbol(symbol: Symbol): Type | undefined { + if (symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { + return getDeclaredTypeOfClassOrInterface(symbol); + } + if (symbol.flags & SymbolFlags.TypeAlias) { + return getDeclaredTypeOfTypeAlias(symbol); + } + if (symbol.flags & SymbolFlags.TypeParameter) { + return getDeclaredTypeOfTypeParameter(symbol); + } + if (symbol.flags & SymbolFlags.Enum) { + return getDeclaredTypeOfEnum(symbol); + } + if (symbol.flags & SymbolFlags.EnumMember) { + return getDeclaredTypeOfEnumMember(symbol); + } + if (symbol.flags & SymbolFlags.Alias) { + return getDeclaredTypeOfAlias(symbol); + } + return undefined; + } + + /** + * A type is free of this references if it's the any, string, number, boolean, symbol, or void keyword, a string + * literal type, an array with an element type that is free of this references, or a type reference that is + * free of this references. + */ + function isThislessType(node: TypeNode): boolean { + switch (node.kind) { + case SyntaxKind.AnyKeyword: + case SyntaxKind.UnknownKeyword: + case SyntaxKind.StringKeyword: + case SyntaxKind.NumberKeyword: + case SyntaxKind.BigIntKeyword: + case SyntaxKind.BooleanKeyword: + case SyntaxKind.SymbolKeyword: + case SyntaxKind.ObjectKeyword: + case SyntaxKind.VoidKeyword: + case SyntaxKind.UndefinedKeyword: + case SyntaxKind.NeverKeyword: + case SyntaxKind.LiteralType: + return true; + case SyntaxKind.ArrayType: + return isThislessType((node as ArrayTypeNode).elementType); + case SyntaxKind.TypeReference: + return !(node as TypeReferenceNode).typeArguments || (node as TypeReferenceNode).typeArguments!.every(isThislessType); + } + return false; + } + + /** A type parameter is thisless if its constraint is thisless, or if it has no constraint. */ + function isThislessTypeParameter(node: TypeParameterDeclaration) { + const constraint = getEffectiveConstraintOfTypeParameter(node); + return !constraint || isThislessType(constraint); + } + + /** + * A variable-like declaration is free of this references if it has a type annotation + * that is thisless, or if it has no type annotation and no initializer (and is thus of type any). + */ + function isThislessVariableLikeDeclaration(node: VariableLikeDeclaration): boolean { + const typeNode = getEffectiveTypeAnnotationNode(node); + return typeNode ? isThislessType(typeNode) : !hasInitializer(node); + } + + /** + * A function-like declaration is considered free of `this` references if it has a return type + * annotation that is free of this references and if each parameter is thisless and if + * each type parameter (if present) is thisless. + */ + function isThislessFunctionLikeDeclaration(node: FunctionLikeDeclaration): boolean { + const returnType = getEffectiveReturnTypeNode(node); + const typeParameters = getEffectiveTypeParameterDeclarations(node); + return (node.kind === SyntaxKind.Constructor || (!!returnType && isThislessType(returnType))) && + node.parameters.every(isThislessVariableLikeDeclaration) && + typeParameters.every(isThislessTypeParameter); + } + + /** + * Returns true if the class or interface member given by the symbol is free of "this" references. The + * function may return false for symbols that are actually free of "this" references because it is not + * feasible to perform a complete analysis in all cases. In particular, property members with types + * inferred from their initializers and function members with inferred return types are conservatively + * assumed not to be free of "this" references. + */ + function isThisless(symbol: Symbol): boolean { + if (symbol.declarations && symbol.declarations.length === 1) { + const declaration = symbol.declarations[0]; + if (declaration) { + switch (declaration.kind) { + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + return isThislessVariableLikeDeclaration(declaration as VariableLikeDeclaration); + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + case SyntaxKind.Constructor: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return isThislessFunctionLikeDeclaration(declaration as FunctionLikeDeclaration | AccessorDeclaration); + } + } + } + return false; + } + + // The mappingThisOnly flag indicates that the only type parameter being mapped is "this". When the flag is true, + // we check symbols to see if we can quickly conclude they are free of "this" references, thus needing no instantiation. + function createInstantiatedSymbolTable(symbols: Symbol[], mapper: TypeMapper, mappingThisOnly: boolean): SymbolTable { + const result = createSymbolTable(); + for (const symbol of symbols) { + result.set(symbol.escapedName, mappingThisOnly && isThisless(symbol) ? symbol : instantiateSymbol(symbol, mapper)); + } + return result; + } + + function addInheritedMembers(symbols: SymbolTable, baseSymbols: Symbol[]) { + for (const base of baseSymbols) { + if (isStaticPrivateIdentifierProperty(base)) { + continue; + } + const derived = symbols.get(base.escapedName); + if ( + !derived + // non-constructor/static-block assignment declarations are ignored here; they're not treated as overrides + || derived.valueDeclaration + && isBinaryExpression(derived.valueDeclaration) + && !isConstructorDeclaredProperty(derived) + && !getContainingClassStaticBlock(derived.valueDeclaration) + ) { + symbols.set(base.escapedName, base); + symbols.set(base.escapedName, base); + } + } + } + + function isStaticPrivateIdentifierProperty(s: Symbol): boolean { + return !!s.valueDeclaration && isPrivateIdentifierClassElementDeclaration(s.valueDeclaration) && isStatic(s.valueDeclaration); + } + + function resolveDeclaredMembers(type: InterfaceType): InterfaceTypeWithDeclaredMembers { + if (!(type as InterfaceTypeWithDeclaredMembers).declaredProperties) { + const symbol = type.symbol; + const members = getMembersOfSymbol(symbol); + (type as InterfaceTypeWithDeclaredMembers).declaredProperties = getNamedMembers(members); + // Start with signatures at empty array in case of recursive types + (type as InterfaceTypeWithDeclaredMembers).declaredCallSignatures = emptyArray; + (type as InterfaceTypeWithDeclaredMembers).declaredConstructSignatures = emptyArray; + (type as InterfaceTypeWithDeclaredMembers).declaredIndexInfos = emptyArray; + + (type as InterfaceTypeWithDeclaredMembers).declaredCallSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.Call)); + (type as InterfaceTypeWithDeclaredMembers).declaredConstructSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.New)); + (type as InterfaceTypeWithDeclaredMembers).declaredIndexInfos = getIndexInfosOfSymbol(symbol); + } + return type as InterfaceTypeWithDeclaredMembers; + } + + /** + * Indicates whether a declaration name is definitely late-bindable. + * A declaration name is only late-bindable if: + * - It is a `ComputedPropertyName`. + * - Its expression is an `Identifier` or either a `PropertyAccessExpression` an + * `ElementAccessExpression` consisting only of these same three types of nodes. + * - The type of its expression is a string or numeric literal type, or is a `unique symbol` type. + */ + function isLateBindableName(node: DeclarationName): node is LateBoundName { + if (!isComputedPropertyName(node) && !isElementAccessExpression(node)) { + return false; + } + const expr = isComputedPropertyName(node) ? node.expression : node.argumentExpression; + return isEntityNameExpression(expr) + && isTypeUsableAsPropertyName(isComputedPropertyName(node) ? checkComputedPropertyName(node) : checkExpressionCached(expr)); + } + + function isLateBoundName(name: __String): boolean { + return (name as string).charCodeAt(0) === CharacterCodes._ && + (name as string).charCodeAt(1) === CharacterCodes._ && + (name as string).charCodeAt(2) === CharacterCodes.at; + } + + /** + * Indicates whether a declaration has a late-bindable dynamic name. + */ + function hasLateBindableName(node: Declaration): node is LateBoundDeclaration | LateBoundBinaryExpressionDeclaration { + const name = getNameOfDeclaration(node); + return !!name && isLateBindableName(name); + } + + /** + * Indicates whether a declaration has an early-bound name or a dynamic name that can be late-bound. + */ + function hasBindableName(node: Declaration) { + return !hasDynamicName(node) || hasLateBindableName(node); + } + + /** + * Indicates whether a declaration name is a dynamic name that cannot be late-bound. + */ + function isNonBindableDynamicName(node: DeclarationName) { + return isDynamicName(node) && !isLateBindableName(node); + } + + /** + * Adds a declaration to a late-bound dynamic member. This performs the same function for + * late-bound members that `addDeclarationToSymbol` in binder.ts performs for early-bound + * members. + */ + function addDeclarationToLateBoundSymbol(symbol: Symbol, member: LateBoundDeclaration | BinaryExpression, symbolFlags: SymbolFlags) { + Debug.assert(!!(getCheckFlags(symbol) & CheckFlags.Late), "Expected a late-bound symbol."); + symbol.flags |= symbolFlags; + getSymbolLinks(member.symbol).lateSymbol = symbol; + if (!symbol.declarations) { + symbol.declarations = [member]; + } + else if (!member.symbol.isReplaceableByMethod) { + symbol.declarations.push(member); + } + if (symbolFlags & SymbolFlags.Value) { + if (!symbol.valueDeclaration || symbol.valueDeclaration.kind !== member.kind) { + symbol.valueDeclaration = member; + } + } + } + + /** + * Performs late-binding of a dynamic member. This performs the same function for + * late-bound members that `declareSymbol` in binder.ts performs for early-bound + * members. + * + * If a symbol is a dynamic name from a computed property, we perform an additional "late" + * binding phase to attempt to resolve the name for the symbol from the type of the computed + * property's expression. If the type of the expression is a string-literal, numeric-literal, + * or unique symbol type, we can use that type as the name of the symbol. + * + * For example, given: + * + * const x = Symbol(); + * + * interface I { + * [x]: number; + * } + * + * The binder gives the property `[x]: number` a special symbol with the name "__computed". + * In the late-binding phase we can type-check the expression `x` and see that it has a + * unique symbol type which we can then use as the name of the member. This allows users + * to define custom symbols that can be used in the members of an object type. + * + * @param parent The containing symbol for the member. + * @param earlySymbols The early-bound symbols of the parent. + * @param lateSymbols The late-bound symbols of the parent. + * @param decl The member to bind. + */ + function lateBindMember(parent: Symbol, earlySymbols: SymbolTable | undefined, lateSymbols: Map<__String, TransientSymbol>, decl: LateBoundDeclaration | LateBoundBinaryExpressionDeclaration) { + Debug.assert(!!decl.symbol, "The member is expected to have a symbol."); + const links = getNodeLinks(decl); + if (!links.resolvedSymbol) { + // In the event we attempt to resolve the late-bound name of this member recursively, + // fall back to the early-bound name of this member. + links.resolvedSymbol = decl.symbol; + const declName = isBinaryExpression(decl) ? decl.left : decl.name; + const type = isElementAccessExpression(declName) ? checkExpressionCached(declName.argumentExpression) : checkComputedPropertyName(declName); + if (isTypeUsableAsPropertyName(type)) { + const memberName = getPropertyNameFromType(type); + const symbolFlags = decl.symbol.flags; + + // Get or add a late-bound symbol for the member. This allows us to merge late-bound accessor declarations. + let lateSymbol = lateSymbols.get(memberName); + if (!lateSymbol) lateSymbols.set(memberName, lateSymbol = createSymbol(SymbolFlags.None, memberName, CheckFlags.Late)); + + // Report an error if there's a symbol declaration with the same name and conflicting flags. + const earlySymbol = earlySymbols && earlySymbols.get(memberName); + // Duplicate property declarations of classes are checked in checkClassForDuplicateDeclarations. + if (!(parent.flags & SymbolFlags.Class) && lateSymbol.flags & getExcludedSymbolFlags(symbolFlags)) { + // If we have an existing early-bound member, combine its declarations so that we can + // report an error at each declaration. + const declarations = earlySymbol ? concatenate(earlySymbol.declarations, lateSymbol.declarations) : lateSymbol.declarations; + const name = !(type.flags & TypeFlags.UniqueESSymbol) && unescapeLeadingUnderscores(memberName) || declarationNameToString(declName); + forEach(declarations, declaration => error(getNameOfDeclaration(declaration) || declaration, Diagnostics.Property_0_was_also_declared_here, name)); + error(declName || decl, Diagnostics.Duplicate_property_0, name); + lateSymbol = createSymbol(SymbolFlags.None, memberName, CheckFlags.Late); + } + lateSymbol.links.nameType = type; + addDeclarationToLateBoundSymbol(lateSymbol, decl, symbolFlags); + if (lateSymbol.parent) { + Debug.assert(lateSymbol.parent === parent, "Existing symbol parent should match new one"); + } + else { + lateSymbol.parent = parent; + } + return links.resolvedSymbol = lateSymbol; + } + } + return links.resolvedSymbol; + } + + function getResolvedMembersOrExportsOfSymbol(symbol: Symbol, resolutionKind: MembersOrExportsResolutionKind): Map<__String, Symbol> { + const links = getSymbolLinks(symbol); + if (!links[resolutionKind]) { + const isStatic = resolutionKind === MembersOrExportsResolutionKind.resolvedExports; + const earlySymbols = !isStatic ? symbol.members : + symbol.flags & SymbolFlags.Module ? getExportsOfModuleWorker(symbol).exports : + symbol.exports; + + // In the event we recursively resolve the members/exports of the symbol, we + // set the initial value of resolvedMembers/resolvedExports to the early-bound + // members/exports of the symbol. + links[resolutionKind] = earlySymbols || emptySymbols; + + // fill in any as-yet-unresolved late-bound members. + const lateSymbols = createSymbolTable() as Map<__String, TransientSymbol>; + for (const decl of symbol.declarations || emptyArray) { + const members = getMembersOfDeclaration(decl); + if (members) { + for (const member of members) { + if (isStatic === hasStaticModifier(member)) { + if (hasLateBindableName(member)) { + lateBindMember(symbol, earlySymbols, lateSymbols, member); + } + } + } + } + } + const assignments = getFunctionExpressionParentSymbolOrSymbol(symbol).assignmentDeclarationMembers; + + if (assignments) { + const decls = arrayFrom(assignments.values()); + for (const member of decls) { + const assignmentKind = getAssignmentDeclarationKind(member as BinaryExpression | CallExpression); + const isInstanceMember = assignmentKind === AssignmentDeclarationKind.PrototypeProperty + || isBinaryExpression(member) && isPossiblyAliasedThisProperty(member, assignmentKind) + || assignmentKind === AssignmentDeclarationKind.ObjectDefinePrototypeProperty + || assignmentKind === AssignmentDeclarationKind.Prototype; // A straight `Prototype` assignment probably can never have a computed name + if (isStatic === !isInstanceMember) { + if (hasLateBindableName(member)) { + lateBindMember(symbol, earlySymbols, lateSymbols, member); + } + } + } + } + + let resolved = combineSymbolTables(earlySymbols, lateSymbols); + if (symbol.flags & SymbolFlags.Transient && links.cjsExportMerged && symbol.declarations) { + for (const decl of symbol.declarations) { + const original = getSymbolLinks(decl.symbol)[resolutionKind]; + if (!resolved) { + resolved = original; + continue; + } + if (!original) continue; + original.forEach((s, name) => { + const existing = resolved!.get(name); + if (!existing) resolved!.set(name, s); + else if (existing === s) return; + else resolved!.set(name, mergeSymbol(existing, s)); + }); + } + } + links[resolutionKind] = resolved || emptySymbols; + } + + return links[resolutionKind]!; + } + + /** + * Gets a SymbolTable containing both the early- and late-bound members of a symbol. + * + * For a description of late-binding, see `lateBindMember`. + */ + function getMembersOfSymbol(symbol: Symbol) { + return symbol.flags & SymbolFlags.LateBindingContainer + ? getResolvedMembersOrExportsOfSymbol(symbol, MembersOrExportsResolutionKind.resolvedMembers) + : symbol.members || emptySymbols; + } + + /** + * If a symbol is the dynamic name of the member of an object type, get the late-bound + * symbol of the member. + * + * For a description of late-binding, see `lateBindMember`. + */ + function getLateBoundSymbol(symbol: Symbol): Symbol { + if (symbol.flags & SymbolFlags.ClassMember && symbol.escapedName === InternalSymbolName.Computed) { + const links = getSymbolLinks(symbol); + if (!links.lateSymbol && some(symbol.declarations, hasLateBindableName)) { + // force late binding of members/exports. This will set the late-bound symbol + const parent = getMergedSymbol(symbol.parent)!; + if (some(symbol.declarations, hasStaticModifier)) { + getExportsOfSymbol(parent); + } + else { + getMembersOfSymbol(parent); + } + } + return links.lateSymbol || (links.lateSymbol = symbol); + } + return symbol; + } + + function getTypeWithThisArgument(type: Type, thisArgument?: Type, needApparentType?: boolean): Type { + if (getObjectFlags(type) & ObjectFlags.Reference) { + const target = (type as TypeReference).target; + const typeArguments = getTypeArguments(type as TypeReference); + return length(target.typeParameters) === length(typeArguments) ? createTypeReference(target, concatenate(typeArguments, [thisArgument || target.thisType!])) : type; + } + else if (type.flags & TypeFlags.Intersection) { + const types = sameMap((type as IntersectionType).types, t => getTypeWithThisArgument(t, thisArgument, needApparentType)); + return types !== (type as IntersectionType).types ? getIntersectionType(types) : type; + } + return needApparentType ? getApparentType(type) : type; + } + + function resolveObjectTypeMembers(type: ObjectType, source: InterfaceTypeWithDeclaredMembers, typeParameters: readonly TypeParameter[], typeArguments: readonly Type[]) { + let mapper: TypeMapper | undefined; + let members: SymbolTable; + let callSignatures: readonly Signature[]; + let constructSignatures: readonly Signature[]; + let indexInfos: readonly IndexInfo[]; + if (rangeEquals(typeParameters, typeArguments, 0, typeParameters.length)) { + members = source.symbol ? getMembersOfSymbol(source.symbol) : createSymbolTable(source.declaredProperties); + callSignatures = source.declaredCallSignatures; + constructSignatures = source.declaredConstructSignatures; + indexInfos = source.declaredIndexInfos; + } + else { + mapper = createTypeMapper(typeParameters, typeArguments); + members = createInstantiatedSymbolTable(source.declaredProperties, mapper, /*mappingThisOnly*/ typeParameters.length === 1); + callSignatures = instantiateSignatures(source.declaredCallSignatures, mapper); + constructSignatures = instantiateSignatures(source.declaredConstructSignatures, mapper); + indexInfos = instantiateIndexInfos(source.declaredIndexInfos, mapper); + } + const baseTypes = getBaseTypes(source); + if (baseTypes.length) { + if (source.symbol && members === getMembersOfSymbol(source.symbol)) { + const symbolTable = createSymbolTable(source.declaredProperties); + // copy index signature symbol as well (for quickinfo) + const sourceIndex = getIndexSymbol(source.symbol); + if (sourceIndex) { + symbolTable.set(InternalSymbolName.Index, sourceIndex); + } + members = symbolTable; + } + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + const thisArgument = lastOrUndefined(typeArguments); + for (const baseType of baseTypes) { + const instantiatedBaseType = thisArgument ? getTypeWithThisArgument(instantiateType(baseType, mapper), thisArgument) : baseType; + addInheritedMembers(members, getPropertiesOfType(instantiatedBaseType)); + callSignatures = concatenate(callSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Call)); + constructSignatures = concatenate(constructSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Construct)); + const inheritedIndexInfos = instantiatedBaseType !== anyType ? getIndexInfosOfType(instantiatedBaseType) : [createIndexInfo(stringType, anyType, /*isReadonly*/ false)]; + indexInfos = concatenate(indexInfos, filter(inheritedIndexInfos, info => !findIndexInfo(indexInfos, info.keyType))); + } + } + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + } + + function resolveClassOrInterfaceMembers(type: InterfaceType): void { + resolveObjectTypeMembers(type, resolveDeclaredMembers(type), emptyArray, emptyArray); + } + + function resolveTypeReferenceMembers(type: TypeReference): void { + const source = resolveDeclaredMembers(type.target); + const typeParameters = concatenate(source.typeParameters!, [source.thisType!]); + const typeArguments = getTypeArguments(type); + const paddedTypeArguments = typeArguments.length === typeParameters.length ? typeArguments : concatenate(typeArguments, [type]); + resolveObjectTypeMembers(type, source, typeParameters, paddedTypeArguments); + } + + function createSignature( + declaration: SignatureDeclaration | JSDocSignature | undefined, + typeParameters: readonly TypeParameter[] | undefined, + thisParameter: Symbol | undefined, + parameters: readonly Symbol[], + resolvedReturnType: Type | undefined, + resolvedTypePredicate: TypePredicate | undefined, + minArgumentCount: number, + flags: SignatureFlags, + ): Signature { + const sig = new Signature(checker, flags); + sig.declaration = declaration; + sig.typeParameters = typeParameters; + sig.parameters = parameters; + sig.thisParameter = thisParameter; + sig.resolvedReturnType = resolvedReturnType; + sig.resolvedTypePredicate = resolvedTypePredicate; + sig.minArgumentCount = minArgumentCount; + sig.resolvedMinArgumentCount = undefined; + sig.target = undefined; + sig.mapper = undefined; + sig.compositeSignatures = undefined; + sig.compositeKind = undefined; + return sig; + } + + function cloneSignature(sig: Signature): Signature { + const result = createSignature(sig.declaration, sig.typeParameters, sig.thisParameter, sig.parameters, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, sig.minArgumentCount, sig.flags & SignatureFlags.PropagatingFlags); + result.target = sig.target; + result.mapper = sig.mapper; + result.compositeSignatures = sig.compositeSignatures; + result.compositeKind = sig.compositeKind; + return result; + } + + function createUnionSignature(signature: Signature, unionSignatures: Signature[]) { + const result = cloneSignature(signature); + result.compositeSignatures = unionSignatures; + result.compositeKind = TypeFlags.Union; + result.target = undefined; + result.mapper = undefined; + return result; + } + + function getOptionalCallSignature(signature: Signature, callChainFlags: SignatureFlags): Signature { + if ((signature.flags & SignatureFlags.CallChainFlags) === callChainFlags) { + return signature; + } + if (!signature.optionalCallSignatureCache) { + signature.optionalCallSignatureCache = {}; + } + const key = callChainFlags === SignatureFlags.IsInnerCallChain ? "inner" : "outer"; + return signature.optionalCallSignatureCache[key] + || (signature.optionalCallSignatureCache[key] = createOptionalCallSignature(signature, callChainFlags)); + } + + function createOptionalCallSignature(signature: Signature, callChainFlags: SignatureFlags) { + Debug.assert(callChainFlags === SignatureFlags.IsInnerCallChain || callChainFlags === SignatureFlags.IsOuterCallChain, "An optional call signature can either be for an inner call chain or an outer call chain, but not both."); + const result = cloneSignature(signature); + result.flags |= callChainFlags; + return result; + } + + function getExpandedParameters(sig: Signature, skipUnionExpanding?: boolean): readonly (readonly Symbol[])[] { + if (signatureHasRestParameter(sig)) { + const restIndex = sig.parameters.length - 1; + const restName = sig.parameters[restIndex].escapedName; + const restType = getTypeOfSymbol(sig.parameters[restIndex]); + if (isTupleType(restType)) { + return [expandSignatureParametersWithTupleMembers(restType, restIndex, restName)]; + } + else if (!skipUnionExpanding && restType.flags & TypeFlags.Union && every((restType as UnionType).types, isTupleType)) { + return map((restType as UnionType).types, t => expandSignatureParametersWithTupleMembers(t as TupleTypeReference, restIndex, restName)); + } + } + return [sig.parameters]; + + function expandSignatureParametersWithTupleMembers(restType: TupleTypeReference, restIndex: number, restName: __String) { + const elementTypes = getTypeArguments(restType); + const associatedNames = getUniqAssociatedNamesFromTupleType(restType, restName); + const restParams = map(elementTypes, (t, i) => { + // Lookup the label from the individual tuple passed in before falling back to the signature `rest` parameter name + const name = associatedNames && associatedNames[i] ? associatedNames[i] : + getParameterNameAtPosition(sig, restIndex + i, restType); + const flags = restType.target.elementFlags[i]; + const checkFlags = flags & ElementFlags.Variable ? CheckFlags.RestParameter : + flags & ElementFlags.Optional ? CheckFlags.OptionalParameter : 0; + const symbol = createSymbol(SymbolFlags.FunctionScopedVariable, name, checkFlags); + symbol.links.type = flags & ElementFlags.Rest ? createArrayType(t) : t; + return symbol; + }); + return concatenate(sig.parameters.slice(0, restIndex), restParams); + } + + function getUniqAssociatedNamesFromTupleType(type: TupleTypeReference, restName: __String) { + const associatedNamesMap = new Map<__String, number>(); + return map(type.target.labeledElementDeclarations, (labeledElement, i) => { + const name = getTupleElementLabel(labeledElement, i, restName); + const prevCounter = associatedNamesMap.get(name); + if (prevCounter === undefined) { + associatedNamesMap.set(name, 1); + return name; + } + else { + associatedNamesMap.set(name, prevCounter + 1); + return `${name}_${prevCounter}` as __String; + } + }); + } + } + + function getDefaultConstructSignatures(classType: InterfaceType): Signature[] { + const baseConstructorType = getBaseConstructorTypeOfClass(classType); + const baseSignatures = getSignaturesOfType(baseConstructorType, SignatureKind.Construct); + const declaration = getClassLikeDeclarationOfSymbol(classType.symbol); + const isAbstract = !!declaration && hasSyntacticModifier(declaration, ModifierFlags.Abstract); + if (baseSignatures.length === 0) { + return [createSignature(/*declaration*/ undefined, classType.localTypeParameters, /*thisParameter*/ undefined, emptyArray, classType, /*resolvedTypePredicate*/ undefined, 0, isAbstract ? SignatureFlags.Abstract : SignatureFlags.None)]; + } + const baseTypeNode = getBaseTypeNodeOfClass(classType)!; + const isJavaScript = isInJSFile(baseTypeNode); + const typeArguments = typeArgumentsFromTypeReferenceNode(baseTypeNode); + const typeArgCount = length(typeArguments); + const result: Signature[] = []; + for (const baseSig of baseSignatures) { + const minTypeArgumentCount = getMinTypeArgumentCount(baseSig.typeParameters); + const typeParamCount = length(baseSig.typeParameters); + if (isJavaScript || typeArgCount >= minTypeArgumentCount && typeArgCount <= typeParamCount) { + const sig = typeParamCount ? createSignatureInstantiation(baseSig, fillMissingTypeArguments(typeArguments, baseSig.typeParameters, minTypeArgumentCount, isJavaScript)) : cloneSignature(baseSig); + sig.typeParameters = classType.localTypeParameters; + sig.resolvedReturnType = classType; + sig.flags = isAbstract ? sig.flags | SignatureFlags.Abstract : sig.flags & ~SignatureFlags.Abstract; + result.push(sig); + } + } + return result; + } + + function findMatchingSignature(signatureList: readonly Signature[], signature: Signature, partialMatch: boolean, ignoreThisTypes: boolean, ignoreReturnTypes: boolean): Signature | undefined { + for (const s of signatureList) { + if (compareSignaturesIdentical(s, signature, partialMatch, ignoreThisTypes, ignoreReturnTypes, partialMatch ? compareTypesSubtypeOf : compareTypesIdentical)) { + return s; + } + } + } + + function findMatchingSignatures(signatureLists: readonly (readonly Signature[])[], signature: Signature, listIndex: number): Signature[] | undefined { + if (signature.typeParameters) { + // We require an exact match for generic signatures, so we only return signatures from the first + // signature list and only if they have exact matches in the other signature lists. + if (listIndex > 0) { + return undefined; + } + for (let i = 1; i < signatureLists.length; i++) { + if (!findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false)) { + return undefined; + } + } + return [signature]; + } + let result: Signature[] | undefined; + for (let i = 0; i < signatureLists.length; i++) { + // Allow matching non-generic signatures to have excess parameters (as a fallback if exact parameter match is not found) and different return types. + // Prefer matching this types if possible. + const match = i === listIndex + ? signature + : findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true) + || findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ true, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true); + if (!match) { + return undefined; + } + result = appendIfUnique(result, match); + } + return result; + } + + // The signatures of a union type are those signatures that are present in each of the constituent types. + // Generic signatures must match exactly, but non-generic signatures are allowed to have extra optional + // parameters and may differ in return types. When signatures differ in return types, the resulting return + // type is the union of the constituent return types. + function getUnionSignatures(signatureLists: readonly (readonly Signature[])[]): Signature[] { + let result: Signature[] | undefined; + let indexWithLengthOverOne: number | undefined; + for (let i = 0; i < signatureLists.length; i++) { + if (signatureLists[i].length === 0) return emptyArray; + if (signatureLists[i].length > 1) { + indexWithLengthOverOne = indexWithLengthOverOne === undefined ? i : -1; // -1 is a signal there are multiple overload sets + } + for (const signature of signatureLists[i]) { + // Only process signatures with parameter lists that aren't already in the result list + if (!result || !findMatchingSignature(result, signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true)) { + const unionSignatures = findMatchingSignatures(signatureLists, signature, i); + if (unionSignatures) { + let s = signature; + // Union the result types when more than one signature matches + if (unionSignatures.length > 1) { + let thisParameter = signature.thisParameter; + const firstThisParameterOfUnionSignatures = forEach(unionSignatures, sig => sig.thisParameter); + if (firstThisParameterOfUnionSignatures) { + const thisType = getIntersectionType(mapDefined(unionSignatures, sig => sig.thisParameter && getTypeOfSymbol(sig.thisParameter))); + thisParameter = createSymbolWithType(firstThisParameterOfUnionSignatures, thisType); + } + s = createUnionSignature(signature, unionSignatures); + s.thisParameter = thisParameter; + } + (result || (result = [])).push(s); + } + } + } + } + if (!length(result) && indexWithLengthOverOne !== -1) { + // No sufficiently similar signature existed to subsume all the other signatures in the union - time to see if we can make a single + // signature that handles all over them. We only do this when there are overloads in only one constituent. + // (Overloads are conditional in nature and having overloads in multiple constituents would necessitate making a power set of + // signatures from the type, whose ordering would be non-obvious) + const masterList = signatureLists[indexWithLengthOverOne !== undefined ? indexWithLengthOverOne : 0]; + let results: Signature[] | undefined = masterList.slice(); + for (const signatures of signatureLists) { + if (signatures !== masterList) { + const signature = signatures[0]; + Debug.assert(!!signature, "getUnionSignatures bails early on empty signature lists and should not have empty lists on second pass"); + results = !!signature.typeParameters && some(results, s => !!s.typeParameters && !compareTypeParametersIdentical(signature.typeParameters, s.typeParameters)) ? undefined : map(results, sig => combineSignaturesOfUnionMembers(sig, signature)); + if (!results) { + break; + } + } + } + result = results; + } + return result || emptyArray; + } + + function compareTypeParametersIdentical(sourceParams: readonly TypeParameter[] | undefined, targetParams: readonly TypeParameter[] | undefined): boolean { + if (length(sourceParams) !== length(targetParams)) { + return false; + } + if (!sourceParams || !targetParams) { + return true; + } + + const mapper = createTypeMapper(targetParams, sourceParams); + for (let i = 0; i < sourceParams.length; i++) { + const source = sourceParams[i]; + const target = targetParams[i]; + if (source === target) continue; + // We instantiate the target type parameter constraints into the source types so we can recognize `` as the same as `` + if (!isTypeIdenticalTo(getConstraintFromTypeParameter(source) || unknownType, instantiateType(getConstraintFromTypeParameter(target) || unknownType, mapper))) return false; + // We don't compare defaults - we just use the type parameter defaults from the first signature that seems to match. + // It might make sense to combine these defaults in the future, but doing so intelligently requires knowing + // if the parameter is used covariantly or contravariantly (so we intersect if it's used like a parameter or union if used like a return type) + // and, since it's just an inference _default_, just picking one arbitrarily works OK. + } + + return true; + } + + function combineUnionThisParam(left: Symbol | undefined, right: Symbol | undefined, mapper: TypeMapper | undefined): Symbol | undefined { + if (!left || !right) { + return left || right; + } + // A signature `this` type might be a read or a write position... It's very possible that it should be invariant + // and we should refuse to merge signatures if there are `this` types and they do not match. However, so as to be + // permissive when calling, for now, we'll intersect the `this` types just like we do for param types in union signatures. + const thisType = getIntersectionType([getTypeOfSymbol(left), instantiateType(getTypeOfSymbol(right), mapper)]); + return createSymbolWithType(left, thisType); + } + + function combineUnionParameters(left: Signature, right: Signature, mapper: TypeMapper | undefined) { + const leftCount = getParameterCount(left); + const rightCount = getParameterCount(right); + const longest = leftCount >= rightCount ? left : right; + const shorter = longest === left ? right : left; + const longestCount = longest === left ? leftCount : rightCount; + const eitherHasEffectiveRest = hasEffectiveRestParameter(left) || hasEffectiveRestParameter(right); + const needsExtraRestElement = eitherHasEffectiveRest && !hasEffectiveRestParameter(longest); + const params = new Array(longestCount + (needsExtraRestElement ? 1 : 0)); + for (let i = 0; i < longestCount; i++) { + let longestParamType = tryGetTypeAtPosition(longest, i)!; + if (longest === right) { + longestParamType = instantiateType(longestParamType, mapper); + } + let shorterParamType = tryGetTypeAtPosition(shorter, i) || unknownType; + if (shorter === right) { + shorterParamType = instantiateType(shorterParamType, mapper); + } + const unionParamType = getIntersectionType([longestParamType, shorterParamType]); + const isRestParam = eitherHasEffectiveRest && !needsExtraRestElement && i === (longestCount - 1); + const isOptional = i >= getMinArgumentCount(longest) && i >= getMinArgumentCount(shorter); + const leftName = i >= leftCount ? undefined : getParameterNameAtPosition(left, i); + const rightName = i >= rightCount ? undefined : getParameterNameAtPosition(right, i); + + const paramName = leftName === rightName ? leftName : + !leftName ? rightName : + !rightName ? leftName : + undefined; + const paramSymbol = createSymbol( + SymbolFlags.FunctionScopedVariable | (isOptional && !isRestParam ? SymbolFlags.Optional : 0), + paramName || `arg${i}` as __String, + isRestParam ? CheckFlags.RestParameter : isOptional ? CheckFlags.OptionalParameter : 0, + ); + paramSymbol.links.type = isRestParam ? createArrayType(unionParamType) : unionParamType; + params[i] = paramSymbol; + } + if (needsExtraRestElement) { + const restParamSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "args" as __String, CheckFlags.RestParameter); + restParamSymbol.links.type = createArrayType(getTypeAtPosition(shorter, longestCount)); + if (shorter === right) { + restParamSymbol.links.type = instantiateType(restParamSymbol.links.type, mapper); + } + params[longestCount] = restParamSymbol; + } + return params; + } + + function combineSignaturesOfUnionMembers(left: Signature, right: Signature): Signature { + const typeParams = left.typeParameters || right.typeParameters; + let paramMapper: TypeMapper | undefined; + if (left.typeParameters && right.typeParameters) { + paramMapper = createTypeMapper(right.typeParameters, left.typeParameters); + // We just use the type parameter defaults from the first signature + } + const declaration = left.declaration; + const params = combineUnionParameters(left, right, paramMapper); + const thisParam = combineUnionThisParam(left.thisParameter, right.thisParameter, paramMapper); + const minArgCount = Math.max(left.minArgumentCount, right.minArgumentCount); + const result = createSignature( + declaration, + typeParams, + thisParam, + params, + /*resolvedReturnType*/ undefined, + /*resolvedTypePredicate*/ undefined, + minArgCount, + (left.flags | right.flags) & SignatureFlags.PropagatingFlags, + ); + result.compositeKind = TypeFlags.Union; + result.compositeSignatures = concatenate(left.compositeKind !== TypeFlags.Intersection && left.compositeSignatures || [left], [right]); + if (paramMapper) { + result.mapper = left.compositeKind !== TypeFlags.Intersection && left.mapper && left.compositeSignatures ? combineTypeMappers(left.mapper, paramMapper) : paramMapper; + } + else if (left.compositeKind !== TypeFlags.Intersection && left.mapper && left.compositeSignatures) { + result.mapper = left.mapper; + } + return result; + } + + function getUnionIndexInfos(types: readonly Type[]): IndexInfo[] { + const sourceInfos = getIndexInfosOfType(types[0]); + if (sourceInfos) { + const result = []; + for (const info of sourceInfos) { + const indexType = info.keyType; + if (every(types, t => !!getIndexInfoOfType(t, indexType))) { + result.push(createIndexInfo(indexType, getUnionType(map(types, t => getIndexTypeOfType(t, indexType)!)), some(types, t => getIndexInfoOfType(t, indexType)!.isReadonly))); + } + } + return result; + } + return emptyArray; + } + + function resolveUnionTypeMembers(type: UnionType) { + // The members and properties collections are empty for union types. To get all properties of a union + // type use getPropertiesOfType (only the language service uses this). + const callSignatures = getUnionSignatures(map(type.types, t => t === globalFunctionType ? [unknownSignature] : getSignaturesOfType(t, SignatureKind.Call))); + const constructSignatures = getUnionSignatures(map(type.types, t => getSignaturesOfType(t, SignatureKind.Construct))); + const indexInfos = getUnionIndexInfos(type.types); + setStructuredTypeMembers(type, emptySymbols, callSignatures, constructSignatures, indexInfos); + } + + function intersectTypes(type1: Type, type2: Type): Type; + function intersectTypes(type1: Type | undefined, type2: Type | undefined): Type | undefined; + function intersectTypes(type1: Type | undefined, type2: Type | undefined): Type | undefined { + return !type1 ? type2 : !type2 ? type1 : getIntersectionType([type1, type2]); + } + + function findMixins(types: readonly Type[]): readonly boolean[] { + const constructorTypeCount = countWhere(types, t => getSignaturesOfType(t, SignatureKind.Construct).length > 0); + const mixinFlags = map(types, isMixinConstructorType); + if (constructorTypeCount > 0 && constructorTypeCount === countWhere(mixinFlags, b => b)) { + const firstMixinIndex = mixinFlags.indexOf(/*searchElement*/ true); + mixinFlags[firstMixinIndex] = false; + } + return mixinFlags; + } + + function includeMixinType(type: Type, types: readonly Type[], mixinFlags: readonly boolean[], index: number): Type { + const mixedTypes: Type[] = []; + for (let i = 0; i < types.length; i++) { + if (i === index) { + mixedTypes.push(type); + } + else if (mixinFlags[i]) { + mixedTypes.push(getReturnTypeOfSignature(getSignaturesOfType(types[i], SignatureKind.Construct)[0])); + } + } + return getIntersectionType(mixedTypes); + } + + function resolveIntersectionTypeMembers(type: IntersectionType) { + // The members and properties collections are empty for intersection types. To get all properties of an + // intersection type use getPropertiesOfType (only the language service uses this). + let callSignatures: Signature[] | undefined; + let constructSignatures: Signature[] | undefined; + let indexInfos: IndexInfo[] | undefined; + const types = type.types; + const mixinFlags = findMixins(types); + const mixinCount = countWhere(mixinFlags, b => b); + for (let i = 0; i < types.length; i++) { + const t = type.types[i]; + // When an intersection type contains mixin constructor types, the construct signatures from + // those types are discarded and their return types are mixed into the return types of all + // other construct signatures in the intersection type. For example, the intersection type + // '{ new(...args: any[]) => A } & { new(s: string) => B }' has a single construct signature + // 'new(s: string) => A & B'. + if (!mixinFlags[i]) { + let signatures = getSignaturesOfType(t, SignatureKind.Construct); + if (signatures.length && mixinCount > 0) { + signatures = map(signatures, s => { + const clone = cloneSignature(s); + clone.resolvedReturnType = includeMixinType(getReturnTypeOfSignature(s), types, mixinFlags, i); + return clone; + }); + } + constructSignatures = appendSignatures(constructSignatures, signatures); + } + callSignatures = appendSignatures(callSignatures, getSignaturesOfType(t, SignatureKind.Call)); + indexInfos = reduceLeft(getIndexInfosOfType(t), (infos, newInfo) => appendIndexInfo(infos, newInfo, /*union*/ false), indexInfos); + } + setStructuredTypeMembers(type, emptySymbols, callSignatures || emptyArray, constructSignatures || emptyArray, indexInfos || emptyArray); + } + + function appendSignatures(signatures: Signature[] | undefined, newSignatures: readonly Signature[]) { + for (const sig of newSignatures) { + if (!signatures || every(signatures, s => !compareSignaturesIdentical(s, sig, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false, compareTypesIdentical))) { + signatures = append(signatures, sig); + } + } + return signatures; + } + + function appendIndexInfo(indexInfos: IndexInfo[] | undefined, newInfo: IndexInfo, union: boolean) { + if (indexInfos) { + for (let i = 0; i < indexInfos.length; i++) { + const info = indexInfos[i]; + if (info.keyType === newInfo.keyType) { + indexInfos[i] = createIndexInfo(info.keyType, union ? getUnionType([info.type, newInfo.type]) : getIntersectionType([info.type, newInfo.type]), union ? info.isReadonly || newInfo.isReadonly : info.isReadonly && newInfo.isReadonly); + return indexInfos; + } + } + } + return append(indexInfos, newInfo); + } + + /** + * Converts an AnonymousType to a ResolvedType. + */ + function resolveAnonymousTypeMembers(type: AnonymousType) { + if (type.target) { + setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); + const members = createInstantiatedSymbolTable(getPropertiesOfObjectType(type.target), type.mapper!, /*mappingThisOnly*/ false); + const callSignatures = instantiateSignatures(getSignaturesOfType(type.target, SignatureKind.Call), type.mapper!); + const constructSignatures = instantiateSignatures(getSignaturesOfType(type.target, SignatureKind.Construct), type.mapper!); + const indexInfos = instantiateIndexInfos(getIndexInfosOfType(type.target), type.mapper!); + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + return; + } + const symbol = getMergedSymbol(type.symbol); + if (symbol.flags & SymbolFlags.TypeLiteral) { + setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); + const members = getMembersOfSymbol(symbol); + const callSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.Call)); + const constructSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.New)); + const indexInfos = getIndexInfosOfSymbol(symbol); + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + return; + } + // Combinations of function, class, enum and module + let members = getExportsOfSymbol(symbol); + let indexInfos: IndexInfo[] | undefined; + if (symbol === globalThisSymbol) { + const varsOnly = new Map<__String, Symbol>(); + members.forEach(p => { + if (!(p.flags & SymbolFlags.BlockScoped) && !(p.flags & SymbolFlags.ValueModule && p.declarations?.length && every(p.declarations, isAmbientModule))) { + varsOnly.set(p.escapedName, p); + } + }); + members = varsOnly; + } + let baseConstructorIndexInfo: IndexInfo | undefined; + setStructuredTypeMembers(type, members, emptyArray, emptyArray, emptyArray); + if (symbol.flags & SymbolFlags.Class) { + const classType = getDeclaredTypeOfClassOrInterface(symbol); + const baseConstructorType = getBaseConstructorTypeOfClass(classType); + if (baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.TypeVariable)) { + members = createSymbolTable(getNamedOrIndexSignatureMembers(members)); + addInheritedMembers(members, getPropertiesOfType(baseConstructorType)); + } + else if (baseConstructorType === anyType) { + baseConstructorIndexInfo = createIndexInfo(stringType, anyType, /*isReadonly*/ false); + } + } + + const indexSymbol = getIndexSymbolFromSymbolTable(members); + if (indexSymbol) { + indexInfos = getIndexInfosOfIndexSymbol(indexSymbol); + } + else { + if (baseConstructorIndexInfo) { + indexInfos = append(indexInfos, baseConstructorIndexInfo); + } + if ( + symbol.flags & SymbolFlags.Enum && (getDeclaredTypeOfSymbol(symbol).flags & TypeFlags.Enum || + some(type.properties, prop => !!(getTypeOfSymbol(prop).flags & TypeFlags.NumberLike))) + ) { + indexInfos = append(indexInfos, enumNumberIndexInfo); + } + } + setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos || emptyArray); + // We resolve the members before computing the signatures because a signature may use + // typeof with a qualified name expression that circularly references the type we are + // in the process of resolving (see issue #6072). The temporarily empty signature list + // will never be observed because a qualified name can't reference signatures. + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method)) { + type.callSignatures = getSignaturesOfSymbol(symbol); + } + // And likewise for construct signatures for classes + if (symbol.flags & SymbolFlags.Class) { + const classType = getDeclaredTypeOfClassOrInterface(symbol); + let constructSignatures = symbol.members ? getSignaturesOfSymbol(symbol.members.get(InternalSymbolName.Constructor)) : emptyArray; + if (symbol.flags & SymbolFlags.Function) { + constructSignatures = addRange( + constructSignatures.slice(), + mapDefined( + type.callSignatures, + sig => + isJSConstructor(sig.declaration) ? + createSignature(sig.declaration, sig.typeParameters, sig.thisParameter, sig.parameters, classType, /*resolvedTypePredicate*/ undefined, sig.minArgumentCount, sig.flags & SignatureFlags.PropagatingFlags) : + undefined, + ), + ); + } + if (!constructSignatures.length) { + constructSignatures = getDefaultConstructSignatures(classType); + } + type.constructSignatures = constructSignatures; + } + } + + type ReplaceableIndexedAccessType = IndexedAccessType & { objectType: TypeParameter; indexType: TypeParameter; }; + function replaceIndexedAccess(instantiable: Type, type: ReplaceableIndexedAccessType, replacement: Type) { + // map type.indexType to 0 + // map type.objectType to `[TReplacement]` + // thus making the indexed access `[TReplacement][0]` or `TReplacement` + return instantiateType(instantiable, createTypeMapper([type.indexType, type.objectType], [getNumberLiteralType(0), createTupleType([replacement])])); + } + + // If the original mapped type had an intersection constraint we extract its components, + // and we make an attempt to do so even if the intersection has been reduced to a union. + // This entire process allows us to possibly retrieve the filtering type literals. + // e.g. { [K in keyof U & ("a" | "b") ] } -> "a" | "b" + function getLimitedConstraint(type: ReverseMappedType) { + const constraint = getConstraintTypeFromMappedType(type.mappedType); + if (!(constraint.flags & TypeFlags.Union || constraint.flags & TypeFlags.Intersection)) { + return; + } + const origin = (constraint.flags & TypeFlags.Union) ? (constraint as UnionType).origin : (constraint as IntersectionType); + if (!origin || !(origin.flags & TypeFlags.Intersection)) { + return; + } + const limitedConstraint = getIntersectionType((origin as IntersectionType).types.filter(t => t !== type.constraintType)); + return limitedConstraint !== neverType ? limitedConstraint : undefined; + } + + function resolveReverseMappedTypeMembers(type: ReverseMappedType) { + const indexInfo = getIndexInfoOfType(type.source, stringType); + const modifiers = getMappedTypeModifiers(type.mappedType); + const readonlyMask = modifiers & MappedTypeModifiers.IncludeReadonly ? false : true; + const optionalMask = modifiers & MappedTypeModifiers.IncludeOptional ? 0 : SymbolFlags.Optional; + const indexInfos = indexInfo ? [createIndexInfo(stringType, inferReverseMappedType(indexInfo.type, type.mappedType, type.constraintType) || unknownType, readonlyMask && indexInfo.isReadonly)] : emptyArray; + const members = createSymbolTable(); + const limitedConstraint = getLimitedConstraint(type); + for (const prop of getPropertiesOfType(type.source)) { + // In case of a reverse mapped type with an intersection constraint, if we were able to + // extract the filtering type literals we skip those properties that are not assignable to them, + // because the extra properties wouldn't get through the application of the mapped type anyway + if (limitedConstraint) { + const propertyNameType = getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique); + if (!isTypeAssignableTo(propertyNameType, limitedConstraint)) { + continue; + } + } + const checkFlags = CheckFlags.ReverseMapped | (readonlyMask && isReadonlySymbol(prop) ? CheckFlags.Readonly : 0); + const inferredProp = createSymbol(SymbolFlags.Property | prop.flags & optionalMask, prop.escapedName, checkFlags) as ReverseMappedSymbol; + inferredProp.declarations = prop.declarations; + inferredProp.links.nameType = getSymbolLinks(prop).nameType; + inferredProp.links.propertyType = getTypeOfSymbol(prop); + if ( + type.constraintType.type.flags & TypeFlags.IndexedAccess + && (type.constraintType.type as IndexedAccessType).objectType.flags & TypeFlags.TypeParameter + && (type.constraintType.type as IndexedAccessType).indexType.flags & TypeFlags.TypeParameter + ) { + // A reverse mapping of `{[K in keyof T[K_1]]: T[K_1]}` is the same as that of `{[K in keyof T]: T}`, since all we care about is + // inferring to the "type parameter" (or indexed access) shared by the constraint and template. So, to reduce the number of + // type identities produced, we simplify such indexed access occurences + const newTypeParam = (type.constraintType.type as IndexedAccessType).objectType; + const newMappedType = replaceIndexedAccess(type.mappedType, type.constraintType.type as ReplaceableIndexedAccessType, newTypeParam); + inferredProp.links.mappedType = newMappedType as MappedType; + inferredProp.links.constraintType = getIndexType(newTypeParam) as IndexType; + } + else { + inferredProp.links.mappedType = type.mappedType; + inferredProp.links.constraintType = type.constraintType; + } + members.set(prop.escapedName, inferredProp); + } + setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos); + } + + // Return the lower bound of the key type in a mapped type. Intuitively, the lower + // bound includes those keys that are known to always be present, for example because + // because of constraints on type parameters (e.g. 'keyof T' for a constrained T). + function getLowerBoundOfKeyType(type: Type): Type { + if (type.flags & TypeFlags.Index) { + const t = getApparentType((type as IndexType).type); + return isGenericTupleType(t) ? getKnownKeysOfTupleType(t) : getIndexType(t); + } + if (type.flags & TypeFlags.Conditional) { + if ((type as ConditionalType).root.isDistributive) { + const checkType = (type as ConditionalType).checkType; + const constraint = getLowerBoundOfKeyType(checkType); + if (constraint !== checkType) { + return getConditionalTypeInstantiation(type as ConditionalType, prependTypeMapping((type as ConditionalType).root.checkType, constraint, (type as ConditionalType).mapper), /*forConstraint*/ false); + } + } + return type; + } + if (type.flags & TypeFlags.Union) { + return mapType(type as UnionType, getLowerBoundOfKeyType, /*noReductions*/ true); + } + if (type.flags & TypeFlags.Intersection) { + // Similarly to getTypeFromIntersectionTypeNode, we preserve the special string & {}, number & {}, + // and bigint & {} intersections that are used to prevent subtype reduction in union types. + const types = (type as IntersectionType).types; + if (types.length === 2 && !!(types[0].flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt)) && types[1] === emptyTypeLiteralType) { + return type; + } + return getIntersectionType(sameMap((type as UnionType).types, getLowerBoundOfKeyType)); + } + return type; + } + + function getIsLateCheckFlag(s: Symbol): CheckFlags { + return getCheckFlags(s) & CheckFlags.Late; + } + + function forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(type: Type, include: TypeFlags, stringsOnly: boolean, cb: (keyType: Type) => void) { + for (const prop of getPropertiesOfType(type)) { + cb(getLiteralTypeFromProperty(prop, include)); + } + if (type.flags & TypeFlags.Any) { + cb(stringType); + } + else { + for (const info of getIndexInfosOfType(type)) { + if (!stringsOnly || info.keyType.flags & (TypeFlags.String | TypeFlags.TemplateLiteral)) { + cb(info.keyType); + } + } + } + } + + /** Resolve the members of a mapped type { [P in K]: T } */ + function resolveMappedTypeMembers(type: MappedType) { + const members: SymbolTable = createSymbolTable(); + let indexInfos: IndexInfo[] | undefined; + // Resolve upfront such that recursive references see an empty object type. + setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); + // In { [P in K]: T }, we refer to P as the type parameter type, K as the constraint type, + // and T as the template type. + const typeParameter = getTypeParameterFromMappedType(type); + const constraintType = getConstraintTypeFromMappedType(type); + const mappedType = (type.target as MappedType) || type; + const nameType = getNameTypeFromMappedType(mappedType); + const shouldLinkPropDeclarations = getMappedTypeNameTypeKind(mappedType) !== MappedTypeNameTypeKind.Remapping; + const templateType = getTemplateTypeFromMappedType(mappedType); + const modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T' + const templateModifiers = getMappedTypeModifiers(type); + const include = TypeFlags.StringOrNumberLiteralOrUnique; + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // We have a { [P in keyof T]: X } + forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(modifiersType, include, /*stringsOnly*/ false, addMemberForKeyType); + } + else { + forEachType(getLowerBoundOfKeyType(constraintType), addMemberForKeyType); + } + setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos || emptyArray); + + function addMemberForKeyType(keyType: Type) { + const propNameType = nameType ? instantiateType(nameType, appendTypeMapping(type.mapper, typeParameter, keyType)) : keyType; + forEachType(propNameType, t => addMemberForKeyTypeWorker(keyType, t)); + } + + function addMemberForKeyTypeWorker(keyType: Type, propNameType: Type) { + // If the current iteration type constituent is a string literal type, create a property. + // Otherwise, for type string create a string index signature. + if (isTypeUsableAsPropertyName(propNameType)) { + const propName = getPropertyNameFromType(propNameType); + // String enum members from separate enums with identical values + // are distinct types with the same property name. Make the resulting + // property symbol's name type be the union of those enum member types. + const existingProp = members.get(propName) as MappedSymbol | undefined; + if (existingProp) { + existingProp.links.nameType = getUnionType([existingProp.links.nameType!, propNameType]); + existingProp.links.keyType = getUnionType([existingProp.links.keyType, keyType]); + } + else { + const modifiersProp = isTypeUsableAsPropertyName(keyType) ? getPropertyOfType(modifiersType, getPropertyNameFromType(keyType)) : undefined; + const isOptional = !!(templateModifiers & MappedTypeModifiers.IncludeOptional || + !(templateModifiers & MappedTypeModifiers.ExcludeOptional) && modifiersProp && modifiersProp.flags & SymbolFlags.Optional); + const isReadonly = !!(templateModifiers & MappedTypeModifiers.IncludeReadonly || + !(templateModifiers & MappedTypeModifiers.ExcludeReadonly) && modifiersProp && isReadonlySymbol(modifiersProp)); + const stripOptional = strictNullChecks && !isOptional && modifiersProp && modifiersProp.flags & SymbolFlags.Optional; + const lateFlag: CheckFlags = modifiersProp ? getIsLateCheckFlag(modifiersProp) : 0; + const prop = createSymbol(SymbolFlags.Property | (isOptional ? SymbolFlags.Optional : 0), propName, lateFlag | CheckFlags.Mapped | (isReadonly ? CheckFlags.Readonly : 0) | (stripOptional ? CheckFlags.StripOptional : 0)) as MappedSymbol; + prop.links.mappedType = type; + prop.links.nameType = propNameType; + prop.links.keyType = keyType; + if (modifiersProp) { + prop.links.syntheticOrigin = modifiersProp; + prop.declarations = shouldLinkPropDeclarations ? modifiersProp.declarations : undefined; + } + members.set(propName, prop); + } + } + else if (isValidIndexKeyType(propNameType) || propNameType.flags & (TypeFlags.Any | TypeFlags.Enum)) { + const indexKeyType = propNameType.flags & (TypeFlags.Any | TypeFlags.String) ? stringType : + propNameType.flags & (TypeFlags.Number | TypeFlags.Enum) ? numberType : + propNameType; + const propType = instantiateType(templateType, appendTypeMapping(type.mapper, typeParameter, keyType)); + const modifiersIndexInfo = getApplicableIndexInfo(modifiersType, propNameType); + const isReadonly = !!(templateModifiers & MappedTypeModifiers.IncludeReadonly || + !(templateModifiers & MappedTypeModifiers.ExcludeReadonly) && modifiersIndexInfo?.isReadonly); + const indexInfo = createIndexInfo(indexKeyType, propType, isReadonly); + indexInfos = appendIndexInfo(indexInfos, indexInfo, /*union*/ true); + } + } + } + + function getTypeOfMappedSymbol(symbol: MappedSymbol) { + if (!symbol.links.type) { + const mappedType = symbol.links.mappedType; + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + mappedType.containsError = true; + return errorType; + } + const templateType = getTemplateTypeFromMappedType(mappedType.target as MappedType || mappedType); + const mapper = appendTypeMapping(mappedType.mapper, getTypeParameterFromMappedType(mappedType), symbol.links.keyType); + const propType = instantiateType(templateType, mapper); + // When creating an optional property in strictNullChecks mode, if 'undefined' isn't assignable to the + // type, we include 'undefined' in the type. Similarly, when creating a non-optional property in strictNullChecks + // mode, if the underlying property is optional we remove 'undefined' from the type. + let type = strictNullChecks && symbol.flags & SymbolFlags.Optional && !maybeTypeOfKind(propType, TypeFlags.Undefined | TypeFlags.Void) ? getOptionalType(propType, /*isProperty*/ true) : + symbol.links.checkFlags & CheckFlags.StripOptional ? removeMissingOrUndefinedType(propType) : + propType; + if (!popTypeResolution()) { + error(currentNode, Diagnostics.Type_of_property_0_circularly_references_itself_in_mapped_type_1, symbolToString(symbol), typeToString(mappedType)); + type = errorType; + } + symbol.links.type ??= type; + } + return symbol.links.type; + } + + function getTypeParameterFromMappedType(type: MappedType) { + return type.typeParameter || + (type.typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(type.declaration.typeParameter))); + } + + function getConstraintTypeFromMappedType(type: MappedType) { + return type.constraintType || + (type.constraintType = getConstraintOfTypeParameter(getTypeParameterFromMappedType(type)) || errorType); + } + + function getNameTypeFromMappedType(type: MappedType) { + return type.declaration.nameType ? + type.nameType || (type.nameType = instantiateType(getTypeFromTypeNode(type.declaration.nameType), type.mapper)) : + undefined; + } + + function getTemplateTypeFromMappedType(type: MappedType) { + return type.templateType || + (type.templateType = type.declaration.type ? + instantiateType(addOptionality(getTypeFromTypeNode(type.declaration.type), /*isProperty*/ true, !!(getMappedTypeModifiers(type) & MappedTypeModifiers.IncludeOptional)), type.mapper) : + errorType); + } + + function getConstraintDeclarationForMappedType(type: MappedType) { + return getEffectiveConstraintOfTypeParameter(type.declaration.typeParameter); + } + + function isMappedTypeWithKeyofConstraintDeclaration(type: MappedType) { + const constraintDeclaration = getConstraintDeclarationForMappedType(type)!; // TODO: GH#18217 + return constraintDeclaration.kind === SyntaxKind.TypeOperator && + (constraintDeclaration as TypeOperatorNode).operator === SyntaxKind.KeyOfKeyword; + } + + function getModifiersTypeFromMappedType(type: MappedType) { + if (!type.modifiersType) { + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // If the constraint declaration is a 'keyof T' node, the modifiers type is T. We check + // AST nodes here because, when T is a non-generic type, the logic below eagerly resolves + // 'keyof T' to a literal union type and we can't recover T from that type. + type.modifiersType = instantiateType(getTypeFromTypeNode((getConstraintDeclarationForMappedType(type) as TypeOperatorNode).type), type.mapper); + } + else { + // Otherwise, get the declared constraint type, and if the constraint type is a type parameter, + // get the constraint of that type parameter. If the resulting type is an indexed type 'keyof T', + // the modifiers type is T. Otherwise, the modifiers type is unknown. + const declaredType = getTypeFromMappedTypeNode(type.declaration) as MappedType; + const constraint = getConstraintTypeFromMappedType(declaredType); + const extendedConstraint = constraint && constraint.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(constraint as TypeParameter) : constraint; + type.modifiersType = extendedConstraint && extendedConstraint.flags & TypeFlags.Index ? instantiateType((extendedConstraint as IndexType).type, type.mapper) : unknownType; + } + } + return type.modifiersType; + } + + function getMappedTypeModifiers(type: MappedType): MappedTypeModifiers { + const declaration = type.declaration; + return (declaration.readonlyToken ? declaration.readonlyToken.kind === SyntaxKind.MinusToken ? MappedTypeModifiers.ExcludeReadonly : MappedTypeModifiers.IncludeReadonly : 0) | + (declaration.questionToken ? declaration.questionToken.kind === SyntaxKind.MinusToken ? MappedTypeModifiers.ExcludeOptional : MappedTypeModifiers.IncludeOptional : 0); + } + + // Return -1, 0, or 1, where -1 means optionality is stripped (i.e. -?), 0 means optionality is unchanged, and 1 means + // optionality is added (i.e. +?). + function getMappedTypeOptionality(type: MappedType): number { + const modifiers = getMappedTypeModifiers(type); + return modifiers & MappedTypeModifiers.ExcludeOptional ? -1 : modifiers & MappedTypeModifiers.IncludeOptional ? 1 : 0; + } + + // Return -1, 0, or 1, for stripped, unchanged, or added optionality respectively. When a homomorphic mapped type doesn't + // modify optionality, recursively consult the optionality of the type being mapped over to see if it strips or adds optionality. + // For intersections, return -1 or 1 when all constituents strip or add optionality, otherwise return 0. + function getCombinedMappedTypeOptionality(type: Type): number { + if (getObjectFlags(type) & ObjectFlags.Mapped) { + return getMappedTypeOptionality(type as MappedType) || getCombinedMappedTypeOptionality(getModifiersTypeFromMappedType(type as MappedType)); + } + if (type.flags & TypeFlags.Intersection) { + const optionality = getCombinedMappedTypeOptionality((type as IntersectionType).types[0]); + return every((type as IntersectionType).types, (t, i) => i === 0 || getCombinedMappedTypeOptionality(t) === optionality) ? optionality : 0; + } + return 0; + } + + function isPartialMappedType(type: Type) { + return !!(getObjectFlags(type) & ObjectFlags.Mapped && getMappedTypeModifiers(type as MappedType) & MappedTypeModifiers.IncludeOptional); + } + + function isGenericMappedType(type: Type): type is MappedType { + if (getObjectFlags(type) & ObjectFlags.Mapped) { + const constraint = getConstraintTypeFromMappedType(type as MappedType); + if (isGenericIndexType(constraint)) { + return true; + } + // A mapped type is generic if the 'as' clause references generic types other than the iteration type. + // To determine this, we substitute the constraint type (that we now know isn't generic) for the iteration + // type and check whether the resulting type is generic. + const nameType = getNameTypeFromMappedType(type as MappedType); + if (nameType && isGenericIndexType(instantiateType(nameType, makeUnaryTypeMapper(getTypeParameterFromMappedType(type as MappedType), constraint)))) { + return true; + } + } + return false; + } + + function getMappedTypeNameTypeKind(type: MappedType): MappedTypeNameTypeKind { + const nameType = getNameTypeFromMappedType(type); + if (!nameType) { + return MappedTypeNameTypeKind.None; + } + return isTypeAssignableTo(nameType, getTypeParameterFromMappedType(type)) ? MappedTypeNameTypeKind.Filtering : MappedTypeNameTypeKind.Remapping; + } + + function resolveStructuredTypeMembers(type: StructuredType): ResolvedType { + if (!(type as ResolvedType).members) { + if (type.flags & TypeFlags.Object) { + if ((type as ObjectType).objectFlags & ObjectFlags.Reference) { + resolveTypeReferenceMembers(type as TypeReference); + } + else if ((type as ObjectType).objectFlags & ObjectFlags.ClassOrInterface) { + resolveClassOrInterfaceMembers(type as InterfaceType); + } + else if ((type as ReverseMappedType).objectFlags & ObjectFlags.ReverseMapped) { + resolveReverseMappedTypeMembers(type as ReverseMappedType); + } + else if ((type as ObjectType).objectFlags & ObjectFlags.Anonymous) { + resolveAnonymousTypeMembers(type as AnonymousType); + } + else if ((type as MappedType).objectFlags & ObjectFlags.Mapped) { + resolveMappedTypeMembers(type as MappedType); + } + else { + Debug.fail("Unhandled object type " + Debug.formatObjectFlags(type.objectFlags)); + } + } + else if (type.flags & TypeFlags.Union) { + resolveUnionTypeMembers(type as UnionType); + } + else if (type.flags & TypeFlags.Intersection) { + resolveIntersectionTypeMembers(type as IntersectionType); + } + else { + Debug.fail("Unhandled type " + Debug.formatTypeFlags(type.flags)); + } + } + return type as ResolvedType; + } + + /** Return properties of an object type or an empty array for other types */ + function getPropertiesOfObjectType(type: Type): Symbol[] { + if (type.flags & TypeFlags.Object) { + return resolveStructuredTypeMembers(type as ObjectType).properties; + } + return emptyArray; + } + + /** If the given type is an object type and that type has a property by the given name, + * return the symbol for that property. Otherwise return undefined. + */ + function getPropertyOfObjectType(type: Type, name: __String): Symbol | undefined { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + const symbol = resolved.members.get(name); + if (symbol && symbolIsValue(symbol)) { + return symbol; + } + } + } + + function getPropertiesOfUnionOrIntersectionType(type: UnionOrIntersectionType): Symbol[] { + if (!type.resolvedProperties) { + const members = createSymbolTable(); + for (const current of type.types) { + for (const prop of getPropertiesOfType(current)) { + if (!members.has(prop.escapedName)) { + const combinedProp = getPropertyOfUnionOrIntersectionType(type, prop.escapedName, /*skipObjectFunctionPropertyAugment*/ !!(type.flags & TypeFlags.Intersection)); + if (combinedProp) { + members.set(prop.escapedName, combinedProp); + } + } + } + // The properties of a union type are those that are present in all constituent types, so + // we only need to check the properties of the first type without index signature + if (type.flags & TypeFlags.Union && getIndexInfosOfType(current).length === 0) { + break; + } + } + type.resolvedProperties = getNamedMembers(members); + } + return type.resolvedProperties; + } + + function getPropertiesOfType(type: Type): Symbol[] { + type = getReducedApparentType(type); + return type.flags & TypeFlags.UnionOrIntersection ? + getPropertiesOfUnionOrIntersectionType(type as UnionType) : + getPropertiesOfObjectType(type); + } + + function forEachPropertyOfType(type: Type, action: (symbol: Symbol, escapedName: __String) => void): void { + type = getReducedApparentType(type); + if (type.flags & TypeFlags.StructuredType) { + resolveStructuredTypeMembers(type as StructuredType).members.forEach((symbol, escapedName) => { + if (isNamedMember(symbol, escapedName)) { + action(symbol, escapedName); + } + }); + } + } + + function isTypeInvalidDueToUnionDiscriminant(contextualType: Type, obj: ObjectLiteralExpression | JsxAttributes): boolean { + const list = obj.properties as NodeArray; + return list.some(property => { + const nameType = property.name && (isJsxNamespacedName(property.name) ? getStringLiteralType(getTextOfJsxAttributeName(property.name)) : getLiteralTypeFromPropertyName(property.name)); + const name = nameType && isTypeUsableAsPropertyName(nameType) ? getPropertyNameFromType(nameType) : undefined; + const expected = name === undefined ? undefined : getTypeOfPropertyOfType(contextualType, name); + return !!expected && isLiteralType(expected) && !isTypeAssignableTo(getTypeOfNode(property), expected); + }); + } + + function getAllPossiblePropertiesOfTypes(types: readonly Type[]): Symbol[] { + const unionType = getUnionType(types); + if (!(unionType.flags & TypeFlags.Union)) { + return getAugmentedPropertiesOfType(unionType); + } + + const props = createSymbolTable(); + for (const memberType of types) { + for (const { escapedName } of getAugmentedPropertiesOfType(memberType)) { + if (!props.has(escapedName)) { + const prop = createUnionOrIntersectionProperty(unionType as UnionType, escapedName); + // May be undefined if the property is private + if (prop) props.set(escapedName, prop); + } + } + } + return arrayFrom(props.values()); + } + + function getConstraintOfType(type: InstantiableType | UnionOrIntersectionType): Type | undefined { + return type.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(type as TypeParameter) : + type.flags & TypeFlags.IndexedAccess ? getConstraintOfIndexedAccess(type as IndexedAccessType) : + type.flags & TypeFlags.Conditional ? getConstraintOfConditionalType(type as ConditionalType) : + getBaseConstraintOfType(type); + } + + function getConstraintOfTypeParameter(typeParameter: TypeParameter): Type | undefined { + return hasNonCircularBaseConstraint(typeParameter) ? getConstraintFromTypeParameter(typeParameter) : undefined; + } + + function isConstMappedType(type: MappedType, depth: number): boolean { + const typeVariable = getHomomorphicTypeVariable(type); + return !!typeVariable && isConstTypeVariable(typeVariable, depth); + } + + function isConstTypeVariable(type: Type | undefined, depth = 0): boolean { + return depth < 5 && !!(type && ( + type.flags & TypeFlags.TypeParameter && some((type as TypeParameter).symbol?.declarations, d => hasSyntacticModifier(d, ModifierFlags.Const)) || + type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, t => isConstTypeVariable(t, depth)) || + type.flags & TypeFlags.IndexedAccess && isConstTypeVariable((type as IndexedAccessType).objectType, depth + 1) || + type.flags & TypeFlags.Conditional && isConstTypeVariable(getConstraintOfConditionalType(type as ConditionalType), depth + 1) || + type.flags & TypeFlags.Substitution && isConstTypeVariable((type as SubstitutionType).baseType, depth) || + getObjectFlags(type) & ObjectFlags.Mapped && isConstMappedType(type as MappedType, depth) || + isGenericTupleType(type) && findIndex(getElementTypes(type), (t, i) => !!(type.target.elementFlags[i] & ElementFlags.Variadic) && isConstTypeVariable(t, depth)) >= 0 + )); + } + + function getConstraintOfIndexedAccess(type: IndexedAccessType) { + return hasNonCircularBaseConstraint(type) ? getConstraintFromIndexedAccess(type) : undefined; + } + + function getSimplifiedTypeOrConstraint(type: Type) { + const simplified = getSimplifiedType(type, /*writing*/ false); + return simplified !== type ? simplified : getConstraintOfType(type); + } + + function getConstraintFromIndexedAccess(type: IndexedAccessType) { + if (isMappedTypeGenericIndexedAccess(type)) { + // For indexed access types of the form { [P in K]: E }[X], where K is non-generic and X is generic, + // we substitute an instantiation of E where P is replaced with X. + return substituteIndexedMappedType(type.objectType as MappedType, type.indexType); + } + const indexConstraint = getSimplifiedTypeOrConstraint(type.indexType); + if (indexConstraint && indexConstraint !== type.indexType) { + const indexedAccess = getIndexedAccessTypeOrUndefined(type.objectType, indexConstraint, type.accessFlags); + if (indexedAccess) { + return indexedAccess; + } + } + const objectConstraint = getSimplifiedTypeOrConstraint(type.objectType); + if (objectConstraint && objectConstraint !== type.objectType) { + return getIndexedAccessTypeOrUndefined(objectConstraint, type.indexType, type.accessFlags); + } + return undefined; + } + + function getDefaultConstraintOfConditionalType(type: ConditionalType) { + if (!type.resolvedDefaultConstraint) { + // An `any` branch of a conditional type would normally be viral - specifically, without special handling here, + // a conditional type with a single branch of type `any` would be assignable to anything, since it's constraint would simplify to + // just `any`. This result is _usually_ unwanted - so instead here we elide an `any` branch from the constraint type, + // in effect treating `any` like `never` rather than `unknown` in this location. + const trueConstraint = getInferredTrueTypeFromConditionalType(type); + const falseConstraint = getFalseTypeFromConditionalType(type); + type.resolvedDefaultConstraint = isTypeAny(trueConstraint) ? falseConstraint : isTypeAny(falseConstraint) ? trueConstraint : getUnionType([trueConstraint, falseConstraint]); + } + return type.resolvedDefaultConstraint; + } + + function getConstraintOfDistributiveConditionalType(type: ConditionalType): Type | undefined { + if (type.resolvedConstraintOfDistributive !== undefined) { + return type.resolvedConstraintOfDistributive || undefined; + } + + // Check if we have a conditional type of the form 'T extends U ? X : Y', where T is a constrained + // type parameter. If so, create an instantiation of the conditional type where T is replaced + // with its constraint. We do this because if the constraint is a union type it will be distributed + // over the conditional type and possibly reduced. For example, 'T extends undefined ? never : T' + // removes 'undefined' from T. + // We skip returning a distributive constraint for a restrictive instantiation of a conditional type + // as the constraint for all type params (check type included) have been replace with `unknown`, which + // is going to produce even more false positive/negative results than the distribute constraint already does. + // Please note: the distributive constraint is a kludge for emulating what a negated type could to do filter + // a union - once negated types exist and are applied to the conditional false branch, this "constraint" + // likely doesn't need to exist. + if (type.root.isDistributive && type.restrictiveInstantiation !== type) { + const simplified = getSimplifiedType(type.checkType, /*writing*/ false); + const constraint = simplified === type.checkType ? getConstraintOfType(simplified) : simplified; + if (constraint && constraint !== type.checkType) { + const instantiated = getConditionalTypeInstantiation(type, prependTypeMapping(type.root.checkType, constraint, type.mapper), /*forConstraint*/ true); + if (!(instantiated.flags & TypeFlags.Never)) { + type.resolvedConstraintOfDistributive = instantiated; + return instantiated; + } + } + } + type.resolvedConstraintOfDistributive = false; + return undefined; + } + + function getConstraintFromConditionalType(type: ConditionalType) { + return getConstraintOfDistributiveConditionalType(type) || getDefaultConstraintOfConditionalType(type); + } + + function getConstraintOfConditionalType(type: ConditionalType) { + return hasNonCircularBaseConstraint(type) ? getConstraintFromConditionalType(type) : undefined; + } + + function getEffectiveConstraintOfIntersection(types: readonly Type[], targetIsUnion: boolean) { + let constraints: Type[] | undefined; + let hasDisjointDomainType = false; + for (const t of types) { + if (t.flags & TypeFlags.Instantiable) { + // We keep following constraints as long as we have an instantiable type that is known + // not to be circular or infinite (hence we stop on index access types). + let constraint = getConstraintOfType(t); + while (constraint && constraint.flags & (TypeFlags.TypeParameter | TypeFlags.Index | TypeFlags.Conditional)) { + constraint = getConstraintOfType(constraint); + } + if (constraint) { + constraints = append(constraints, constraint); + if (targetIsUnion) { + constraints = append(constraints, t); + } + } + } + else if (t.flags & TypeFlags.DisjointDomains || isEmptyAnonymousObjectType(t)) { + hasDisjointDomainType = true; + } + } + // If the target is a union type or if we are intersecting with types belonging to one of the + // disjoint domains, we may end up producing a constraint that hasn't been examined before. + if (constraints && (targetIsUnion || hasDisjointDomainType)) { + if (hasDisjointDomainType) { + // We add any types belong to one of the disjoint domains because they might cause the final + // intersection operation to reduce the union constraints. + for (const t of types) { + if (t.flags & TypeFlags.DisjointDomains || isEmptyAnonymousObjectType(t)) { + constraints = append(constraints, t); + } + } + } + // The source types were normalized; ensure the result is normalized too. + return getNormalizedType(getIntersectionType(constraints, IntersectionFlags.NoConstraintReduction), /*writing*/ false); + } + return undefined; + } + + function getBaseConstraintOfType(type: Type): Type | undefined { + if (type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.UnionOrIntersection | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || isGenericTupleType(type)) { + const constraint = getResolvedBaseConstraint(type as InstantiableType | UnionOrIntersectionType); + return constraint !== noConstraintType && constraint !== circularConstraintType ? constraint : undefined; + } + return type.flags & TypeFlags.Index ? stringNumberSymbolType : undefined; + } + + /** + * This is similar to `getBaseConstraintOfType` except it returns the input type if there's no base constraint, instead of `undefined` + * It also doesn't map indexes to `string`, as where this is used this would be unneeded (and likely undesirable) + */ + function getBaseConstraintOrType(type: Type) { + return getBaseConstraintOfType(type) || type; + } + + function hasNonCircularBaseConstraint(type: InstantiableType): boolean { + return getResolvedBaseConstraint(type) !== circularConstraintType; + } + + /** + * Return the resolved base constraint of a type variable. The noConstraintType singleton is returned if the + * type variable has no constraint, and the circularConstraintType singleton is returned if the constraint + * circularly references the type variable. + */ + function getResolvedBaseConstraint(type: InstantiableType | UnionOrIntersectionType): Type { + if (type.resolvedBaseConstraint) { + return type.resolvedBaseConstraint; + } + const stack: object[] = []; + return type.resolvedBaseConstraint = getImmediateBaseConstraint(type); + + function getImmediateBaseConstraint(t: Type): Type { + if (!t.immediateBaseConstraint) { + if (!pushTypeResolution(t, TypeSystemPropertyName.ImmediateBaseConstraint)) { + return circularConstraintType; + } + let result; + // We always explore at least 10 levels of nested constraints. Thereafter, we continue to explore + // up to 50 levels of nested constraints provided there are no "deeply nested" types on the stack + // (i.e. no types for which five instantiations have been recorded on the stack). If we reach 50 + // levels of nesting, we are presumably exploring a repeating pattern with a long cycle that hasn't + // yet triggered the deeply nested limiter. We have no test cases that actually get to 50 levels of + // nesting, so it is effectively just a safety stop. + const identity = getRecursionIdentity(t); + if (stack.length < 10 || stack.length < 50 && !contains(stack, identity)) { + stack.push(identity); + result = computeBaseConstraint(getSimplifiedType(t, /*writing*/ false)); + stack.pop(); + } + if (!popTypeResolution()) { + if (t.flags & TypeFlags.TypeParameter) { + const errorNode = getConstraintDeclaration(t as TypeParameter); + if (errorNode) { + const diagnostic = error(errorNode, Diagnostics.Type_parameter_0_has_a_circular_constraint, typeToString(t)); + if (currentNode && !isNodeDescendantOf(errorNode, currentNode) && !isNodeDescendantOf(currentNode, errorNode)) { + addRelatedInfo(diagnostic, createDiagnosticForNode(currentNode, Diagnostics.Circularity_originates_in_type_at_this_location)); + } + } + } + result = circularConstraintType; + } + t.immediateBaseConstraint ??= result || noConstraintType; + } + return t.immediateBaseConstraint; + } + + function getBaseConstraint(t: Type): Type | undefined { + const c = getImmediateBaseConstraint(t); + return c !== noConstraintType && c !== circularConstraintType ? c : undefined; + } + + function computeBaseConstraint(t: Type): Type | undefined { + if (t.flags & TypeFlags.TypeParameter) { + const constraint = getConstraintFromTypeParameter(t as TypeParameter); + return (t as TypeParameter).isThisType || !constraint ? + constraint : + getBaseConstraint(constraint); + } + if (t.flags & TypeFlags.UnionOrIntersection) { + const types = (t as UnionOrIntersectionType).types; + const baseTypes: Type[] = []; + let different = false; + for (const type of types) { + const baseType = getBaseConstraint(type); + if (baseType) { + if (baseType !== type) { + different = true; + } + baseTypes.push(baseType); + } + else { + different = true; + } + } + if (!different) { + return t; + } + return t.flags & TypeFlags.Union && baseTypes.length === types.length ? getUnionType(baseTypes) : + t.flags & TypeFlags.Intersection && baseTypes.length ? getIntersectionType(baseTypes) : + undefined; + } + if (t.flags & TypeFlags.Index) { + return stringNumberSymbolType; + } + if (t.flags & TypeFlags.TemplateLiteral) { + const types = (t as TemplateLiteralType).types; + const constraints = mapDefined(types, getBaseConstraint); + return constraints.length === types.length ? getTemplateLiteralType((t as TemplateLiteralType).texts, constraints) : stringType; + } + if (t.flags & TypeFlags.StringMapping) { + const constraint = getBaseConstraint((t as StringMappingType).type); + return constraint && constraint !== (t as StringMappingType).type ? getStringMappingType((t as StringMappingType).symbol, constraint) : stringType; + } + if (t.flags & TypeFlags.IndexedAccess) { + if (isMappedTypeGenericIndexedAccess(t)) { + // For indexed access types of the form { [P in K]: E }[X], where K is non-generic and X is generic, + // we substitute an instantiation of E where P is replaced with X. + return getBaseConstraint(substituteIndexedMappedType((t as IndexedAccessType).objectType as MappedType, (t as IndexedAccessType).indexType)); + } + const baseObjectType = getBaseConstraint((t as IndexedAccessType).objectType); + const baseIndexType = getBaseConstraint((t as IndexedAccessType).indexType); + const baseIndexedAccess = baseObjectType && baseIndexType && getIndexedAccessTypeOrUndefined(baseObjectType, baseIndexType, (t as IndexedAccessType).accessFlags); + return baseIndexedAccess && getBaseConstraint(baseIndexedAccess); + } + if (t.flags & TypeFlags.Conditional) { + const constraint = getConstraintFromConditionalType(t as ConditionalType); + return constraint && getBaseConstraint(constraint); + } + if (t.flags & TypeFlags.Substitution) { + return getBaseConstraint(getSubstitutionIntersection(t as SubstitutionType)); + } + if (isGenericTupleType(t)) { + // We substitute constraints for variadic elements only when the constraints are array types or + // non-variadic tuple types as we want to avoid further (possibly unbounded) recursion. + const newElements = map(getElementTypes(t), (v, i) => { + const constraint = v.flags & TypeFlags.TypeParameter && t.target.elementFlags[i] & ElementFlags.Variadic && getBaseConstraint(v) || v; + return constraint !== v && everyType(constraint, c => isArrayOrTupleType(c) && !isGenericTupleType(c)) ? constraint : v; + }); + return createTupleType(newElements, t.target.elementFlags, t.target.readonly, t.target.labeledElementDeclarations); + } + return t; + } + } + + function getApparentTypeOfIntersectionType(type: IntersectionType, thisArgument: Type) { + if (type === thisArgument) { + return type.resolvedApparentType || (type.resolvedApparentType = getTypeWithThisArgument(type, thisArgument, /*needApparentType*/ true)); + } + const key = `I${getTypeId(type)},${getTypeId(thisArgument)}`; + return getCachedType(key) ?? setCachedType(key, getTypeWithThisArgument(type, thisArgument, /*needApparentType*/ true)); + } + + function getResolvedTypeParameterDefault(typeParameter: TypeParameter): Type | undefined { + if (!typeParameter.default) { + if (typeParameter.target) { + const targetDefault = getResolvedTypeParameterDefault(typeParameter.target); + typeParameter.default = targetDefault ? instantiateType(targetDefault, typeParameter.mapper) : noConstraintType; + } + else { + // To block recursion, set the initial value to the resolvingDefaultType. + typeParameter.default = resolvingDefaultType; + const defaultDeclaration = typeParameter.symbol && forEach(typeParameter.symbol.declarations, decl => isTypeParameterDeclaration(decl) && decl.default); + const defaultType = defaultDeclaration ? getTypeFromTypeNode(defaultDeclaration) : noConstraintType; + if (typeParameter.default === resolvingDefaultType) { + // If we have not been called recursively, set the correct default type. + typeParameter.default = defaultType; + } + } + } + else if (typeParameter.default === resolvingDefaultType) { + // If we are called recursively for this type parameter, mark the default as circular. + typeParameter.default = circularConstraintType; + } + return typeParameter.default; + } + + /** + * Gets the default type for a type parameter. + * + * If the type parameter is the result of an instantiation, this gets the instantiated + * default type of its target. If the type parameter has no default type or the default is + * circular, `undefined` is returned. + */ + function getDefaultFromTypeParameter(typeParameter: TypeParameter): Type | undefined { + const defaultType = getResolvedTypeParameterDefault(typeParameter); + return defaultType !== noConstraintType && defaultType !== circularConstraintType ? defaultType : undefined; + } + + function hasNonCircularTypeParameterDefault(typeParameter: TypeParameter) { + return getResolvedTypeParameterDefault(typeParameter) !== circularConstraintType; + } + + /** + * Indicates whether the declaration of a typeParameter has a default type. + */ + function hasTypeParameterDefault(typeParameter: TypeParameter): boolean { + return !!(typeParameter.symbol && forEach(typeParameter.symbol.declarations, decl => isTypeParameterDeclaration(decl) && decl.default)); + } + + function getApparentTypeOfMappedType(type: MappedType) { + return type.resolvedApparentType || (type.resolvedApparentType = getResolvedApparentTypeOfMappedType(type)); + } + + function getResolvedApparentTypeOfMappedType(type: MappedType): Type { + const target = (type.target ?? type) as MappedType; + const typeVariable = getHomomorphicTypeVariable(target); + if (typeVariable && !target.declaration.nameType) { + // We have a homomorphic mapped type or an instantiation of a homomorphic mapped type, i.e. a type + // of the form { [P in keyof T]: X }. Obtain the modifiers type (the T of the keyof T), and if it is + // another generic mapped type, recursively obtain its apparent type. Otherwise, obtain its base + // constraint. Then, if every constituent of the base constraint is an array or tuple type, apply + // this mapped type to the base constraint. It is safe to recurse when the modifiers type is a + // mapped type because we protect again circular constraints in getTypeFromMappedTypeNode. + const modifiersType = getModifiersTypeFromMappedType(type); + const baseConstraint = isGenericMappedType(modifiersType) ? getApparentTypeOfMappedType(modifiersType) : getBaseConstraintOfType(modifiersType); + if (baseConstraint && everyType(baseConstraint, t => isArrayOrTupleType(t) || isArrayOrTupleOrIntersection(t))) { + return instantiateType(target, prependTypeMapping(typeVariable, baseConstraint, type.mapper)); + } + } + return type; + } + + function isArrayOrTupleOrIntersection(type: Type) { + return !!(type.flags & TypeFlags.Intersection) && every((type as IntersectionType).types, isArrayOrTupleType); + } + + function isMappedTypeGenericIndexedAccess(type: Type) { + let objectType; + return !!(type.flags & TypeFlags.IndexedAccess && getObjectFlags(objectType = (type as IndexedAccessType).objectType) & ObjectFlags.Mapped && + !isGenericMappedType(objectType) && isGenericIndexType((type as IndexedAccessType).indexType) && + !(getMappedTypeModifiers(objectType as MappedType) & MappedTypeModifiers.ExcludeOptional) && !(objectType as MappedType).declaration.nameType); + } + + /** + * For a type parameter, return the base constraint of the type parameter. For the string, number, + * boolean, and symbol primitive types, return the corresponding object types. Otherwise return the + * type itself. + */ + function getApparentType(type: Type): Type { + const t = type.flags & TypeFlags.Instantiable ? getBaseConstraintOfType(type) || unknownType : type; + const objectFlags = getObjectFlags(t); + return objectFlags & ObjectFlags.Mapped ? getApparentTypeOfMappedType(t as MappedType) : + objectFlags & ObjectFlags.Reference && t !== type ? getTypeWithThisArgument(t, type) : + t.flags & TypeFlags.Intersection ? getApparentTypeOfIntersectionType(t as IntersectionType, type) : + t.flags & TypeFlags.StringLike ? globalStringType : + t.flags & TypeFlags.NumberLike ? globalNumberType : + t.flags & TypeFlags.BigIntLike ? getGlobalBigIntType() : + t.flags & TypeFlags.BooleanLike ? globalBooleanType : + t.flags & TypeFlags.ESSymbolLike ? getGlobalESSymbolType() : + t.flags & TypeFlags.NonPrimitive ? emptyObjectType : + t.flags & TypeFlags.Index ? stringNumberSymbolType : + t.flags & TypeFlags.Unknown && !strictNullChecks ? emptyObjectType : + t; + } + + function getReducedApparentType(type: Type): Type { + // Since getApparentType may return a non-reduced union or intersection type, we need to perform + // type reduction both before and after obtaining the apparent type. For example, given a type parameter + // 'T extends A | B', the type 'T & X' becomes 'A & X | B & X' after obtaining the apparent type, and + // that type may need further reduction to remove empty intersections. + return getReducedType(getApparentType(getReducedType(type))); + } + + function createUnionOrIntersectionProperty(containingType: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { + let singleProp: Symbol | undefined; + let propSet: Map | undefined; + let indexTypes: Type[] | undefined; + const isUnion = containingType.flags & TypeFlags.Union; + // Flags we want to propagate to the result if they exist in all source symbols + let optionalFlag: SymbolFlags | undefined; + let syntheticFlag = CheckFlags.SyntheticMethod; + let checkFlags = isUnion ? 0 : CheckFlags.Readonly; + let mergedInstantiations = false; + for (const current of containingType.types) { + const type = getApparentType(current); + if (!(isErrorType(type) || type.flags & TypeFlags.Never)) { + const prop = getPropertyOfType(type, name, skipObjectFunctionPropertyAugment); + const modifiers = prop ? getDeclarationModifierFlagsFromSymbol(prop) : 0; + if (prop) { + if (prop.flags & SymbolFlags.ClassMember) { + optionalFlag ??= isUnion ? SymbolFlags.None : SymbolFlags.Optional; + if (isUnion) { + optionalFlag |= prop.flags & SymbolFlags.Optional; + } + else { + optionalFlag &= prop.flags; + } + } + if (!singleProp) { + singleProp = prop; + } + else if (prop !== singleProp) { + const isInstantiation = (getTargetSymbol(prop) || prop) === (getTargetSymbol(singleProp) || singleProp); + // If the symbols are instances of one another with identical types - consider the symbols + // equivalent and just use the first one, which thus allows us to avoid eliding private + // members when intersecting a (this-)instantiations of a class with its raw base or another instance + if (isInstantiation && compareProperties(singleProp, prop, (a, b) => a === b ? Ternary.True : Ternary.False) === Ternary.True) { + // If we merged instantiations of a generic type, we replicate the symbol parent resetting behavior we used + // to do when we recorded multiple distinct symbols so that we still get, eg, `Array.length` printed + // back and not `Array.length` when we're looking at a `.length` access on a `string[] | number[]` + mergedInstantiations = !!singleProp.parent && !!length(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(singleProp.parent)); + } + else { + if (!propSet) { + propSet = new Map(); + propSet.set(getSymbolId(singleProp), singleProp); + } + const id = getSymbolId(prop); + if (!propSet.has(id)) { + propSet.set(id, prop); + } + } + } + if (isUnion && isReadonlySymbol(prop)) { + checkFlags |= CheckFlags.Readonly; + } + else if (!isUnion && !isReadonlySymbol(prop)) { + checkFlags &= ~CheckFlags.Readonly; + } + checkFlags |= (!(modifiers & ModifierFlags.NonPublicAccessibilityModifier) ? CheckFlags.ContainsPublic : 0) | + (modifiers & ModifierFlags.Protected ? CheckFlags.ContainsProtected : 0) | + (modifiers & ModifierFlags.Private ? CheckFlags.ContainsPrivate : 0) | + (modifiers & ModifierFlags.Static ? CheckFlags.ContainsStatic : 0); + if (!isPrototypeProperty(prop)) { + syntheticFlag = CheckFlags.SyntheticProperty; + } + } + else if (isUnion) { + const indexInfo = !isLateBoundName(name) && getApplicableIndexInfoForName(type, name); + if (indexInfo) { + checkFlags |= CheckFlags.WritePartial | (indexInfo.isReadonly ? CheckFlags.Readonly : 0); + indexTypes = append(indexTypes, isTupleType(type) ? getRestTypeOfTupleType(type) || undefinedType : indexInfo.type); + } + else if (isObjectLiteralType(type) && !(getObjectFlags(type) & ObjectFlags.ContainsSpread)) { + checkFlags |= CheckFlags.WritePartial; + indexTypes = append(indexTypes, undefinedType); + } + else { + checkFlags |= CheckFlags.ReadPartial; + } + } + } + } + if ( + !singleProp || + isUnion && + (propSet || checkFlags & CheckFlags.Partial) && + checkFlags & (CheckFlags.ContainsPrivate | CheckFlags.ContainsProtected) && + !(propSet && getCommonDeclarationsOfSymbols(propSet.values())) + ) { + // No property was found, or, in a union, a property has a private or protected declaration in one + // constituent, but is missing or has a different declaration in another constituent. + return undefined; + } + if (!propSet && !(checkFlags & CheckFlags.ReadPartial) && !indexTypes) { + if (mergedInstantiations) { + // No symbol from a union/intersection should have a `.parent` set (since unions/intersections don't act as symbol parents) + // Unless that parent is "reconstituted" from the "first value declaration" on the symbol (which is likely different than its instantiated parent!) + // They also have a `.containingType` set, which affects some services endpoints behavior, like `getRootSymbol` + const links = tryCast(singleProp, isTransientSymbol)?.links; + const clone = createSymbolWithType(singleProp, links?.type); + clone.parent = singleProp.valueDeclaration?.symbol?.parent; + clone.links.containingType = containingType; + clone.links.mapper = links?.mapper; + clone.links.writeType = getWriteTypeOfSymbol(singleProp); + return clone; + } + else { + return singleProp; + } + } + const props = propSet ? arrayFrom(propSet.values()) : [singleProp]; + let declarations: Declaration[] | undefined; + let firstType: Type | undefined; + let nameType: Type | undefined; + const propTypes: Type[] = []; + let writeTypes: Type[] | undefined; + let firstValueDeclaration: Declaration | undefined; + let hasNonUniformValueDeclaration = false; + for (const prop of props) { + if (!firstValueDeclaration) { + firstValueDeclaration = prop.valueDeclaration; + } + else if (prop.valueDeclaration && prop.valueDeclaration !== firstValueDeclaration) { + hasNonUniformValueDeclaration = true; + } + declarations = addRange(declarations, prop.declarations); + const type = getTypeOfSymbol(prop); + if (!firstType) { + firstType = type; + nameType = getSymbolLinks(prop).nameType; + } + const writeType = getWriteTypeOfSymbol(prop); + if (writeTypes || writeType !== type) { + writeTypes = append(!writeTypes ? propTypes.slice() : writeTypes, writeType); + } + if (type !== firstType) { + checkFlags |= CheckFlags.HasNonUniformType; + } + if (isLiteralType(type) || isPatternLiteralType(type)) { + checkFlags |= CheckFlags.HasLiteralType; + } + if (type.flags & TypeFlags.Never && type !== uniqueLiteralType) { + checkFlags |= CheckFlags.HasNeverType; + } + propTypes.push(type); + } + addRange(propTypes, indexTypes); + const result = createSymbol(SymbolFlags.Property | (optionalFlag ?? 0), name, syntheticFlag | checkFlags); + result.links.containingType = containingType; + if (!hasNonUniformValueDeclaration && firstValueDeclaration) { + result.valueDeclaration = firstValueDeclaration; + + // Inherit information about parent type. + if (firstValueDeclaration.symbol.parent) { + result.parent = firstValueDeclaration.symbol.parent; + } + } + + result.declarations = declarations; + result.links.nameType = nameType; + if (propTypes.length > 2) { + // When `propTypes` has the potential to explode in size when normalized, defer normalization until absolutely needed + result.links.checkFlags |= CheckFlags.DeferredType; + result.links.deferralParent = containingType; + result.links.deferralConstituents = propTypes; + result.links.deferralWriteConstituents = writeTypes; + } + else { + result.links.type = isUnion ? getUnionType(propTypes) : getIntersectionType(propTypes); + if (writeTypes) { + result.links.writeType = isUnion ? getUnionType(writeTypes) : getIntersectionType(writeTypes); + } + } + return result; + } + + // Return the symbol for a given property in a union or intersection type, or undefined if the property + // does not exist in any constituent type. Note that the returned property may only be present in some + // constituents, in which case the isPartial flag is set when the containing type is union type. We need + // these partial properties when identifying discriminant properties, but otherwise they are filtered out + // and do not appear to be present in the union type. + function getUnionOrIntersectionProperty(type: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { + let property = skipObjectFunctionPropertyAugment ? + type.propertyCacheWithoutObjectFunctionPropertyAugment?.get(name) : + type.propertyCache?.get(name); + if (!property) { + property = createUnionOrIntersectionProperty(type, name, skipObjectFunctionPropertyAugment); + if (property) { + const properties = skipObjectFunctionPropertyAugment ? + type.propertyCacheWithoutObjectFunctionPropertyAugment ||= createSymbolTable() : + type.propertyCache ||= createSymbolTable(); + properties.set(name, property); + // Propagate an entry from the non-augmented cache to the augmented cache unless the property is partial. + if (skipObjectFunctionPropertyAugment && !(getCheckFlags(property) & CheckFlags.Partial) && !type.propertyCache?.get(name)) { + const properties = type.propertyCache ||= createSymbolTable(); + properties.set(name, property); + } + } + } + return property; + } + + function getCommonDeclarationsOfSymbols(symbols: Iterable) { + let commonDeclarations: Set | undefined; + for (const symbol of symbols) { + if (!symbol.declarations) { + return undefined; + } + if (!commonDeclarations) { + commonDeclarations = new Set(symbol.declarations); + continue; + } + commonDeclarations.forEach(declaration => { + if (!contains(symbol.declarations, declaration)) { + commonDeclarations!.delete(declaration); + } + }); + if (commonDeclarations.size === 0) { + return undefined; + } + } + return commonDeclarations; + } + + function getPropertyOfUnionOrIntersectionType(type: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { + const property = getUnionOrIntersectionProperty(type, name, skipObjectFunctionPropertyAugment); + // We need to filter out partial properties in union types + return property && !(getCheckFlags(property) & CheckFlags.ReadPartial) ? property : undefined; + } + + /** + * Return the reduced form of the given type. For a union type, it is a union of the normalized constituent types. + * For an intersection of types containing one or more mututally exclusive discriminant properties, it is 'never'. + * For all other types, it is simply the type itself. Discriminant properties are considered mutually exclusive when + * no constituent property has type 'never', but the intersection of the constituent property types is 'never'. + */ + function getReducedType(type: Type): Type { + if (type.flags & TypeFlags.Union && (type as UnionType).objectFlags & ObjectFlags.ContainsIntersections) { + return (type as UnionType).resolvedReducedType || ((type as UnionType).resolvedReducedType = getReducedUnionType(type as UnionType)); + } + else if (type.flags & TypeFlags.Intersection) { + if (!((type as IntersectionType).objectFlags & ObjectFlags.IsNeverIntersectionComputed)) { + (type as IntersectionType).objectFlags |= ObjectFlags.IsNeverIntersectionComputed | + (some(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isNeverReducedProperty) ? ObjectFlags.IsNeverIntersection : 0); + } + return (type as IntersectionType).objectFlags & ObjectFlags.IsNeverIntersection ? neverType : type; + } + return type; + } + + function getReducedUnionType(unionType: UnionType) { + const reducedTypes = sameMap(unionType.types, getReducedType); + if (reducedTypes === unionType.types) { + return unionType; + } + const reduced = getUnionType(reducedTypes); + if (reduced.flags & TypeFlags.Union) { + (reduced as UnionType).resolvedReducedType = reduced; + } + return reduced; + } + + function isNeverReducedProperty(prop: Symbol) { + return isDiscriminantWithNeverType(prop) || isConflictingPrivateProperty(prop); + } + + function isDiscriminantWithNeverType(prop: Symbol) { + // Return true for a synthetic non-optional property with non-uniform types, where at least one is + // a literal type and none is never, that reduces to never. + return !(prop.flags & SymbolFlags.Optional) && + (getCheckFlags(prop) & (CheckFlags.Discriminant | CheckFlags.HasNeverType)) === CheckFlags.Discriminant && + !!(getTypeOfSymbol(prop).flags & TypeFlags.Never); + } + + function isConflictingPrivateProperty(prop: Symbol) { + // Return true for a synthetic property with multiple declarations, at least one of which is private. + return !prop.valueDeclaration && !!(getCheckFlags(prop) & CheckFlags.ContainsPrivate); + } + + /** + * A union type which is reducible upon instantiation (meaning some members are removed under certain instantiations) + * must be kept generic, as that instantiation information needs to flow through the type system. By replacing all + * type parameters in the union with a special never type that is treated as a literal in `getReducedType`, we can cause + * the `getReducedType` logic to reduce the resulting type if possible (since only intersections with conflicting + * literal-typed properties are reducible). + */ + function isGenericReducibleType(type: Type): boolean { + return !!(type.flags & TypeFlags.Union && (type as UnionType).objectFlags & ObjectFlags.ContainsIntersections && some((type as UnionType).types, isGenericReducibleType) || + type.flags & TypeFlags.Intersection && isReducibleIntersection(type as IntersectionType)); + } + + function isReducibleIntersection(type: IntersectionType) { + const uniqueFilled = type.uniqueLiteralFilledInstantiation || (type.uniqueLiteralFilledInstantiation = instantiateType(type, uniqueLiteralMapper)); + return getReducedType(uniqueFilled) !== uniqueFilled; + } + + function elaborateNeverIntersection(errorInfo: DiagnosticMessageChain | undefined, type: Type) { + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsNeverIntersection) { + const neverProp = find(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isDiscriminantWithNeverType); + if (neverProp) { + return chainDiagnosticMessages(errorInfo, Diagnostics.The_intersection_0_was_reduced_to_never_because_property_1_has_conflicting_types_in_some_constituents, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.NoTypeReduction), symbolToString(neverProp)); + } + const privateProp = find(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isConflictingPrivateProperty); + if (privateProp) { + return chainDiagnosticMessages(errorInfo, Diagnostics.The_intersection_0_was_reduced_to_never_because_property_1_exists_in_multiple_constituents_and_is_private_in_some, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.NoTypeReduction), symbolToString(privateProp)); + } + } + return errorInfo; + } + + /** + * Return the symbol for the property with the given name in the given type. Creates synthetic union properties when + * necessary, maps primitive types and type parameters are to their apparent types, and augments with properties from + * Object and Function as appropriate. + * + * @param type a type to look up property from + * @param name a name of property to look up in a given type + */ + function getPropertyOfType(type: Type, name: __String, skipObjectFunctionPropertyAugment?: boolean, includeTypeOnlyMembers?: boolean): Symbol | undefined { + type = getReducedApparentType(type); + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + const symbol = resolved.members.get(name); + if (symbol && !includeTypeOnlyMembers && type.symbol?.flags & SymbolFlags.ValueModule && getSymbolLinks(type.symbol).typeOnlyExportStarMap?.has(name)) { + // If this is the type of a module, `resolved.members.get(name)` might have effectively skipped over + // an `export type * from './foo'`, leaving `symbolIsValue` unable to see that the symbol is being + // viewed through a type-only export. + return undefined; + } + if (symbol && symbolIsValue(symbol, includeTypeOnlyMembers)) { + return symbol; + } + if (skipObjectFunctionPropertyAugment) return undefined; + const functionType = resolved === anyFunctionType ? globalFunctionType : + resolved.callSignatures.length ? globalCallableFunctionType : + resolved.constructSignatures.length ? globalNewableFunctionType : + undefined; + if (functionType) { + const symbol = getPropertyOfObjectType(functionType, name); + if (symbol) { + return symbol; + } + } + return getPropertyOfObjectType(globalObjectType, name); + } + if (type.flags & TypeFlags.Intersection) { + const prop = getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, /*skipObjectFunctionPropertyAugment*/ true); + if (prop) { + return prop; + } + if (!skipObjectFunctionPropertyAugment) { + return getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, skipObjectFunctionPropertyAugment); + } + return undefined; + } + if (type.flags & TypeFlags.Union) { + return getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, skipObjectFunctionPropertyAugment); + } + return undefined; + } + + function getSignaturesOfStructuredType(type: Type, kind: SignatureKind): readonly Signature[] { + if (type.flags & TypeFlags.StructuredType) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + return kind === SignatureKind.Call ? resolved.callSignatures : resolved.constructSignatures; + } + return emptyArray; + } + + /** + * Return the signatures of the given kind in the given type. Creates synthetic union signatures when necessary and + * maps primitive types and type parameters are to their apparent types. + */ + function getSignaturesOfType(type: Type, kind: SignatureKind): readonly Signature[] { + const result = getSignaturesOfStructuredType(getReducedApparentType(type), kind); + if (kind === SignatureKind.Call && !length(result) && type.flags & TypeFlags.Union) { + if ((type as UnionType).arrayFallbackSignatures) { + return (type as UnionType).arrayFallbackSignatures!; + } + // If the union is all different instantiations of a member of the global array type... + let memberName: __String; + if (everyType(type, t => !!t.symbol?.parent && isArrayOrTupleSymbol(t.symbol.parent) && (!memberName ? (memberName = t.symbol.escapedName, true) : memberName === t.symbol.escapedName))) { + // Transform the type from `(A[] | B[])["member"]` to `(A | B)[]["member"]` (since we pretend array is covariant anyway) + const arrayArg = mapType(type, t => getMappedType((isReadonlyArraySymbol(t.symbol.parent) ? globalReadonlyArrayType : globalArrayType).typeParameters![0], (t as AnonymousType).mapper!)); + const arrayType = createArrayType(arrayArg, someType(type, t => isReadonlyArraySymbol(t.symbol.parent))); + return (type as UnionType).arrayFallbackSignatures = getSignaturesOfType(getTypeOfPropertyOfType(arrayType, memberName!)!, kind); + } + (type as UnionType).arrayFallbackSignatures = result; + } + return result; + } + + function isArrayOrTupleSymbol(symbol: Symbol | undefined) { + if (!symbol || !globalArrayType.symbol || !globalReadonlyArrayType.symbol) { + return false; + } + return !!getSymbolIfSameReference(symbol, globalArrayType.symbol) || !!getSymbolIfSameReference(symbol, globalReadonlyArrayType.symbol); + } + + function isReadonlyArraySymbol(symbol: Symbol | undefined) { + if (!symbol || !globalReadonlyArrayType.symbol) { + return false; + } + return !!getSymbolIfSameReference(symbol, globalReadonlyArrayType.symbol); + } + + function findIndexInfo(indexInfos: readonly IndexInfo[], keyType: Type) { + return find(indexInfos, info => info.keyType === keyType); + } + + function findApplicableIndexInfo(indexInfos: readonly IndexInfo[], keyType: Type) { + // Index signatures for type 'string' are considered only when no other index signatures apply. + let stringIndexInfo: IndexInfo | undefined; + let applicableInfo: IndexInfo | undefined; + let applicableInfos: IndexInfo[] | undefined; + for (const info of indexInfos) { + if (info.keyType === stringType) { + stringIndexInfo = info; + } + else if (isApplicableIndexType(keyType, info.keyType)) { + if (!applicableInfo) { + applicableInfo = info; + } + else { + (applicableInfos || (applicableInfos = [applicableInfo])).push(info); + } + } + } + // When more than one index signature is applicable we create a synthetic IndexInfo. Instead of computing + // the intersected key type, we just use unknownType for the key type as nothing actually depends on the + // keyType property of the returned IndexInfo. + return applicableInfos ? createIndexInfo(unknownType, getIntersectionType(map(applicableInfos, info => info.type)), reduceLeft(applicableInfos, (isReadonly, info) => isReadonly && info.isReadonly, /*initial*/ true)) : + applicableInfo ? applicableInfo : + stringIndexInfo && isApplicableIndexType(keyType, stringType) ? stringIndexInfo : + undefined; + } + + function isApplicableIndexType(source: Type, target: Type): boolean { + // A 'string' index signature applies to types assignable to 'string' or 'number', and a 'number' index + // signature applies to types assignable to 'number', `${number}` and numeric string literal types. + return isTypeAssignableTo(source, target) || + target === stringType && isTypeAssignableTo(source, numberType) || + target === numberType && (source === numericStringType || !!(source.flags & TypeFlags.StringLiteral) && isNumericLiteralName((source as StringLiteralType).value)); + } + + function getIndexInfosOfStructuredType(type: Type): readonly IndexInfo[] { + if (type.flags & TypeFlags.StructuredType) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + return resolved.indexInfos; + } + return emptyArray; + } + + function getIndexInfosOfType(type: Type): readonly IndexInfo[] { + return getIndexInfosOfStructuredType(getReducedApparentType(type)); + } + + // Return the indexing info of the given kind in the given type. Creates synthetic union index types when necessary and + // maps primitive types and type parameters are to their apparent types. + function getIndexInfoOfType(type: Type, keyType: Type): IndexInfo | undefined { + return findIndexInfo(getIndexInfosOfType(type), keyType); + } + + // Return the index type of the given kind in the given type. Creates synthetic union index types when necessary and + // maps primitive types and type parameters are to their apparent types. + function getIndexTypeOfType(type: Type, keyType: Type): Type | undefined { + return getIndexInfoOfType(type, keyType)?.type; + } + + function getApplicableIndexInfos(type: Type, keyType: Type): IndexInfo[] { + return getIndexInfosOfType(type).filter(info => isApplicableIndexType(keyType, info.keyType)); + } + + function getApplicableIndexInfo(type: Type, keyType: Type): IndexInfo | undefined { + return findApplicableIndexInfo(getIndexInfosOfType(type), keyType); + } + + function getApplicableIndexInfoForName(type: Type, name: __String): IndexInfo | undefined { + return getApplicableIndexInfo(type, isLateBoundName(name) ? esSymbolType : getStringLiteralType(unescapeLeadingUnderscores(name))); + } + + // Return list of type parameters with duplicates removed (duplicate identifier errors are generated in the actual + // type checking functions). + function getTypeParametersFromDeclaration(declaration: DeclarationWithTypeParameters): readonly TypeParameter[] | undefined { + let result: TypeParameter[] | undefined; + for (const node of getEffectiveTypeParameterDeclarations(declaration)) { + result = appendIfUnique(result, getDeclaredTypeOfTypeParameter(node.symbol)); + } + return result?.length ? result + : isFunctionDeclaration(declaration) ? getSignatureOfTypeTag(declaration)?.typeParameters + : undefined; + } + + function symbolsToArray(symbols: SymbolTable): Symbol[] { + const result: Symbol[] = []; + symbols.forEach((symbol, id) => { + if (!isReservedMemberName(id)) { + result.push(symbol); + } + }); + return result; + } + + function tryFindAmbientModule(moduleName: string, withAugmentations: boolean) { + if (isExternalModuleNameRelative(moduleName)) { + return undefined; + } + const symbol = getSymbol(globals, '"' + moduleName + '"' as __String, SymbolFlags.ValueModule); + // merged symbol is module declaration symbol combined with all augmentations + return symbol && withAugmentations ? getMergedSymbol(symbol) : symbol; + } + + function hasEffectiveQuestionToken(node: ParameterDeclaration | JSDocParameterTag | JSDocPropertyTag) { + return hasQuestionToken(node) || isOptionalJSDocPropertyLikeTag(node) || isParameter(node) && isJSDocOptionalParameter(node); + } + + function isOptionalParameter(node: ParameterDeclaration | JSDocParameterTag | JSDocPropertyTag) { + if (hasEffectiveQuestionToken(node)) { + return true; + } + if (!isParameter(node)) { + return false; + } + if (node.initializer) { + const signature = getSignatureFromDeclaration(node.parent); + const parameterIndex = node.parent.parameters.indexOf(node); + Debug.assert(parameterIndex >= 0); + // Only consider syntactic or instantiated parameters as optional, not `void` parameters as this function is used + // in grammar checks and checking for `void` too early results in parameter types widening too early + // and causes some noImplicitAny errors to be lost. + return parameterIndex >= getMinArgumentCount(signature, MinArgumentCountFlags.StrongArityForUntypedJS | MinArgumentCountFlags.VoidIsNonOptional); + } + const iife = getImmediatelyInvokedFunctionExpression(node.parent); + if (iife) { + return !node.type && + !node.dotDotDotToken && + node.parent.parameters.indexOf(node) >= getEffectiveCallArguments(iife).length; + } + + return false; + } + + function isOptionalPropertyDeclaration(node: Declaration) { + return isPropertyDeclaration(node) && !hasAccessorModifier(node) && node.questionToken; + } + + function createTypePredicate(kind: TypePredicateKind, parameterName: string | undefined, parameterIndex: number | undefined, type: Type | undefined): TypePredicate { + return { kind, parameterName, parameterIndex, type } as TypePredicate; + } + + /** + * Gets the minimum number of type arguments needed to satisfy all non-optional type + * parameters. + */ + function getMinTypeArgumentCount(typeParameters: readonly TypeParameter[] | undefined): number { + let minTypeArgumentCount = 0; + if (typeParameters) { + for (let i = 0; i < typeParameters.length; i++) { + if (!hasTypeParameterDefault(typeParameters[i])) { + minTypeArgumentCount = i + 1; + } + } + } + return minTypeArgumentCount; + } + + /** + * Fill in default types for unsupplied type arguments. If `typeArguments` is undefined + * when a default type is supplied, a new array will be created and returned. + * + * @param typeArguments The supplied type arguments. + * @param typeParameters The requested type parameters. + * @param minTypeArgumentCount The minimum number of required type arguments. + */ + function fillMissingTypeArguments(typeArguments: readonly Type[], typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean): Type[]; + function fillMissingTypeArguments(typeArguments: readonly Type[] | undefined, typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean): Type[] | undefined; + function fillMissingTypeArguments(typeArguments: readonly Type[] | undefined, typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean) { + const numTypeParameters = length(typeParameters); + if (!numTypeParameters) { + return []; + } + const numTypeArguments = length(typeArguments); + if (isJavaScriptImplicitAny || (numTypeArguments >= minTypeArgumentCount && numTypeArguments <= numTypeParameters)) { + const result = typeArguments ? typeArguments.slice() : []; + // Map invalid forward references in default types to the error type + for (let i = numTypeArguments; i < numTypeParameters; i++) { + result[i] = errorType; + } + const baseDefaultType = getDefaultTypeArgumentType(isJavaScriptImplicitAny); + for (let i = numTypeArguments; i < numTypeParameters; i++) { + let defaultType = getDefaultFromTypeParameter(typeParameters![i]); + if (isJavaScriptImplicitAny && defaultType && (isTypeIdenticalTo(defaultType, unknownType) || isTypeIdenticalTo(defaultType, emptyObjectType))) { + defaultType = anyType; + } + result[i] = defaultType ? instantiateType(defaultType, createTypeMapper(typeParameters!, result)) : baseDefaultType; + } + result.length = typeParameters!.length; + return result; + } + return typeArguments && typeArguments.slice(); + } + + function getSignatureFromDeclaration(declaration: SignatureDeclaration | JSDocSignature): Signature { + const links = getNodeLinks(declaration); + if (!links.resolvedSignature) { + const parameters: Symbol[] = []; + let flags = SignatureFlags.None; + let minArgumentCount = 0; + let thisParameter: Symbol | undefined; + let thisTag: JSDocThisTag | undefined = isInJSFile(declaration) ? getJSDocThisTag(declaration) : undefined; + let hasThisParameter = false; + const iife = getImmediatelyInvokedFunctionExpression(declaration); + const isJSConstructSignature = isJSDocConstructSignature(declaration); + const isUntypedSignatureInJSFile = !iife && + isInJSFile(declaration) && + isValueSignatureDeclaration(declaration) && + !hasJSDocParameterTags(declaration) && + !getJSDocType(declaration); + if (isUntypedSignatureInJSFile) { + flags |= SignatureFlags.IsUntypedSignatureInJSFile; + } + + // If this is a JSDoc construct signature, then skip the first parameter in the + // parameter list. The first parameter represents the return type of the construct + // signature. + for (let i = isJSConstructSignature ? 1 : 0; i < declaration.parameters.length; i++) { + const param = declaration.parameters[i]; + if (isInJSFile(param) && isJSDocThisTag(param)) { + thisTag = param; + continue; + } + + let paramSymbol = param.symbol; + const type = isJSDocParameterTag(param) ? (param.typeExpression && param.typeExpression.type) : param.type; + // Include parameter symbol instead of property symbol in the signature + if (paramSymbol && !!(paramSymbol.flags & SymbolFlags.Property) && !isBindingPattern(param.name)) { + const resolvedSymbol = resolveName(param, paramSymbol.escapedName, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + paramSymbol = resolvedSymbol!; + } + if (i === 0 && paramSymbol.escapedName === InternalSymbolName.This) { + hasThisParameter = true; + thisParameter = param.symbol; + } + else { + parameters.push(paramSymbol); + } + + if (type && type.kind === SyntaxKind.LiteralType) { + flags |= SignatureFlags.HasLiteralTypes; + } + + // Record a new minimum argument count if this is not an optional parameter + const isOptionalParameter = hasEffectiveQuestionToken(param) || + isParameter(param) && param.initializer || isRestParameter(param) || + iife && parameters.length > iife.arguments.length && !type; + if (!isOptionalParameter) { + minArgumentCount = parameters.length; + } + } + + // If only one accessor includes a this-type annotation, the other behaves as if it had the same type annotation + if ( + (declaration.kind === SyntaxKind.GetAccessor || declaration.kind === SyntaxKind.SetAccessor) && + hasBindableName(declaration) && + (!hasThisParameter || !thisParameter) + ) { + const otherKind = declaration.kind === SyntaxKind.GetAccessor ? SyntaxKind.SetAccessor : SyntaxKind.GetAccessor; + const other = getDeclarationOfKind(getSymbolOfDeclaration(declaration), otherKind); + if (other) { + thisParameter = getAnnotatedAccessorThisParameter(other); + } + } + + if (thisTag && thisTag.typeExpression) { + thisParameter = createSymbolWithType(createSymbol(SymbolFlags.FunctionScopedVariable, InternalSymbolName.This), getTypeFromTypeNode(thisTag.typeExpression)); + } + + const hostDeclaration = isJSDocSignature(declaration) ? getEffectiveJSDocHost(declaration) : declaration; + const classType = hostDeclaration && isConstructorDeclaration(hostDeclaration) ? + getDeclaredTypeOfClassOrInterface(getMergedSymbol((hostDeclaration.parent as ClassDeclaration).symbol)) + : undefined; + const typeParameters = classType ? classType.localTypeParameters : getTypeParametersFromDeclaration(declaration); + if (hasRestParameter(declaration) || isInJSFile(declaration) && maybeAddJsSyntheticRestParameter(declaration, parameters)) { + flags |= SignatureFlags.HasRestParameter; + } + if ( + isConstructorTypeNode(declaration) && hasSyntacticModifier(declaration, ModifierFlags.Abstract) || + isConstructorDeclaration(declaration) && hasSyntacticModifier(declaration.parent, ModifierFlags.Abstract) + ) { + flags |= SignatureFlags.Abstract; + } + links.resolvedSignature = createSignature(declaration, typeParameters, thisParameter, parameters, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, minArgumentCount, flags); + } + return links.resolvedSignature; + } + + /** + * A JS function gets a synthetic rest parameter if it references `arguments` AND: + * 1. It has no parameters but at least one `@param` with a type that starts with `...` + * OR + * 2. It has at least one parameter, and the last parameter has a matching `@param` with a type that starts with `...` + */ + function maybeAddJsSyntheticRestParameter(declaration: SignatureDeclaration | JSDocSignature, parameters: Symbol[]): boolean { + if (isJSDocSignature(declaration) || !containsArgumentsReference(declaration)) { + return false; + } + const lastParam = lastOrUndefined(declaration.parameters); + const lastParamTags = lastParam ? getJSDocParameterTags(lastParam) : getJSDocTags(declaration).filter(isJSDocParameterTag); + const lastParamVariadicType = firstDefined(lastParamTags, p => p.typeExpression && isJSDocVariadicType(p.typeExpression.type) ? p.typeExpression.type : undefined); + + const syntheticArgsSymbol = createSymbol(SymbolFlags.Variable, "args" as __String, CheckFlags.RestParameter); + if (lastParamVariadicType) { + // Parameter has effective annotation, lock in type + syntheticArgsSymbol.links.type = createArrayType(getTypeFromTypeNode(lastParamVariadicType.type)); + } + else { + // Parameter has no annotation + // By using a `DeferredType` symbol, we allow the type of this rest arg to be overriden by contextual type assignment so long as its type hasn't been + // cached by `getTypeOfSymbol` yet. + syntheticArgsSymbol.links.checkFlags |= CheckFlags.DeferredType; + syntheticArgsSymbol.links.deferralParent = neverType; + syntheticArgsSymbol.links.deferralConstituents = [anyArrayType]; + syntheticArgsSymbol.links.deferralWriteConstituents = [anyArrayType]; + } + if (lastParamVariadicType) { + // Replace the last parameter with a rest parameter. + parameters.pop(); + } + parameters.push(syntheticArgsSymbol); + return true; + } + + function getSignatureOfTypeTag(node: SignatureDeclaration | JSDocSignature) { + // should be attached to a function declaration or expression + if (!(isInJSFile(node) && isFunctionLikeDeclaration(node))) return undefined; + const typeTag = getJSDocTypeTag(node); + return typeTag?.typeExpression && getSingleCallSignature(getTypeFromTypeNode(typeTag.typeExpression)); + } + + function getParameterTypeOfTypeTag(func: FunctionLikeDeclaration, parameter: ParameterDeclaration) { + const signature = getSignatureOfTypeTag(func); + if (!signature) return undefined; + const pos = func.parameters.indexOf(parameter); + return parameter.dotDotDotToken ? getRestTypeAtPosition(signature, pos) : getTypeAtPosition(signature, pos); + } + + function getReturnTypeOfTypeTag(node: SignatureDeclaration | JSDocSignature) { + const signature = getSignatureOfTypeTag(node); + return signature && getReturnTypeOfSignature(signature); + } + + function containsArgumentsReference(declaration: SignatureDeclaration): boolean { + const links = getNodeLinks(declaration); + if (links.containsArgumentsReference === undefined) { + if (links.flags & NodeCheckFlags.CaptureArguments) { + links.containsArgumentsReference = true; + } + else { + links.containsArgumentsReference = traverse((declaration as FunctionLikeDeclaration).body!); + } + } + return links.containsArgumentsReference; + + function traverse(node: Node): boolean { + if (!node) return false; + switch (node.kind) { + case SyntaxKind.Identifier: + return (node as Identifier).escapedText === argumentsSymbol.escapedName && getReferencedValueSymbol(node as Identifier) === argumentsSymbol; + + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return (node as NamedDeclaration).name!.kind === SyntaxKind.ComputedPropertyName + && traverse((node as NamedDeclaration).name!); + + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + return traverse((node as PropertyAccessExpression | ElementAccessExpression).expression); + + case SyntaxKind.PropertyAssignment: + return traverse((node as PropertyAssignment).initializer); + + default: + return !nodeStartsNewLexicalEnvironment(node) && !isPartOfTypeNode(node) && !!forEachChild(node, traverse); + } + } + } + + function getSignaturesOfSymbol(symbol: Symbol | undefined): Signature[] { + if (!symbol || !symbol.declarations) return emptyArray; + const result: Signature[] = []; + for (let i = 0; i < symbol.declarations.length; i++) { + const decl = symbol.declarations[i]; + if (!isFunctionLike(decl)) continue; + // Don't include signature if node is the implementation of an overloaded function. A node is considered + // an implementation node if it has a body and the previous node is of the same kind and immediately + // precedes the implementation node (i.e. has the same parent and ends where the implementation starts). + if (i > 0 && (decl as FunctionLikeDeclaration).body) { + const previous = symbol.declarations[i - 1]; + if (decl.parent === previous.parent && decl.kind === previous.kind && decl.pos === previous.end) { + continue; + } + } + if (isInJSFile(decl) && decl.jsDoc) { + const tags = getJSDocOverloadTags(decl); + if (length(tags)) { + for (const tag of tags) { + const jsDocSignature = tag.typeExpression; + if (jsDocSignature.type === undefined && !isConstructorDeclaration(decl)) { + reportImplicitAny(jsDocSignature, anyType); + } + result.push(getSignatureFromDeclaration(jsDocSignature)); + } + continue; + } + } + // If this is a function or method declaration, get the signature from the @type tag for the sake of optional parameters. + // Exclude contextually-typed kinds because we already apply the @type tag to the context, plus applying it here to the initializer would supress checks that the two are compatible. + result.push( + (!isFunctionExpressionOrArrowFunction(decl) && + !isObjectLiteralMethod(decl) && + getSignatureOfTypeTag(decl)) || + getSignatureFromDeclaration(decl), + ); + } + return result; + } + + function resolveExternalModuleTypeByLiteral(name: StringLiteral) { + const moduleSym = resolveExternalModuleName(name, name); + if (moduleSym) { + const resolvedModuleSymbol = resolveExternalModuleSymbol(moduleSym); + if (resolvedModuleSymbol) { + return getTypeOfSymbol(resolvedModuleSymbol); + } + } + + return anyType; + } + + function getThisTypeOfSignature(signature: Signature): Type | undefined { + if (signature.thisParameter) { + return getTypeOfSymbol(signature.thisParameter); + } + } + + function getTypePredicateOfSignature(signature: Signature): TypePredicate | undefined { + if (!signature.resolvedTypePredicate) { + if (signature.target) { + const targetTypePredicate = getTypePredicateOfSignature(signature.target); + signature.resolvedTypePredicate = targetTypePredicate ? instantiateTypePredicate(targetTypePredicate, signature.mapper!) : noTypePredicate; + } + else if (signature.compositeSignatures) { + signature.resolvedTypePredicate = getUnionOrIntersectionTypePredicate(signature.compositeSignatures, signature.compositeKind) || noTypePredicate; + } + else { + const type = signature.declaration && getEffectiveReturnTypeNode(signature.declaration); + let jsdocPredicate: TypePredicate | undefined; + if (!type) { + const jsdocSignature = getSignatureOfTypeTag(signature.declaration!); + if (jsdocSignature && signature !== jsdocSignature) { + jsdocPredicate = getTypePredicateOfSignature(jsdocSignature); + } + } + if (type || jsdocPredicate) { + signature.resolvedTypePredicate = type && isTypePredicateNode(type) ? + createTypePredicateFromTypePredicateNode(type, signature) : + jsdocPredicate || noTypePredicate; + } + else if (signature.declaration && isFunctionLikeDeclaration(signature.declaration) && (!signature.resolvedReturnType || signature.resolvedReturnType.flags & TypeFlags.Boolean) && getParameterCount(signature) > 0) { + const { declaration } = signature; + signature.resolvedTypePredicate = noTypePredicate; // avoid infinite loop + signature.resolvedTypePredicate = getTypePredicateFromBody(declaration) || noTypePredicate; + } + else { + signature.resolvedTypePredicate = noTypePredicate; + } + } + Debug.assert(!!signature.resolvedTypePredicate); + } + return signature.resolvedTypePredicate === noTypePredicate ? undefined : signature.resolvedTypePredicate; + } + + function createTypePredicateFromTypePredicateNode(node: TypePredicateNode, signature: Signature): TypePredicate { + const parameterName = node.parameterName; + const type = node.type && getTypeFromTypeNode(node.type); + return parameterName.kind === SyntaxKind.ThisType ? + createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsThis : TypePredicateKind.This, /*parameterName*/ undefined, /*parameterIndex*/ undefined, type) : + createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsIdentifier : TypePredicateKind.Identifier, parameterName.escapedText as string, findIndex(signature.parameters, p => p.escapedName === parameterName.escapedText), type); + } + + function getUnionOrIntersectionType(types: Type[], kind: TypeFlags | undefined, unionReduction?: UnionReduction) { + return kind !== TypeFlags.Intersection ? getUnionType(types, unionReduction) : getIntersectionType(types); + } + + function getReturnTypeOfSignature(signature: Signature): Type { + if (!signature.resolvedReturnType) { + if (!pushTypeResolution(signature, TypeSystemPropertyName.ResolvedReturnType)) { + return errorType; + } + let type = signature.target ? instantiateType(getReturnTypeOfSignature(signature.target), signature.mapper) : + signature.compositeSignatures ? instantiateType(getUnionOrIntersectionType(map(signature.compositeSignatures, getReturnTypeOfSignature), signature.compositeKind, UnionReduction.Subtype), signature.mapper) : + getReturnTypeFromAnnotation(signature.declaration!) || + (nodeIsMissing((signature.declaration as FunctionLikeDeclaration).body) ? anyType : getReturnTypeFromBody(signature.declaration as FunctionLikeDeclaration)); + if (signature.flags & SignatureFlags.IsInnerCallChain) { + type = addOptionalTypeMarker(type); + } + else if (signature.flags & SignatureFlags.IsOuterCallChain) { + type = getOptionalType(type); + } + if (!popTypeResolution()) { + if (signature.declaration) { + const typeNode = getEffectiveReturnTypeNode(signature.declaration); + if (typeNode) { + error(typeNode, Diagnostics.Return_type_annotation_circularly_references_itself); + } + else if (noImplicitAny) { + const declaration = signature.declaration as Declaration; + const name = getNameOfDeclaration(declaration); + if (name) { + error(name, Diagnostics._0_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions, declarationNameToString(name)); + } + else { + error(declaration, Diagnostics.Function_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions); + } + } + } + type = anyType; + } + signature.resolvedReturnType ??= type; + } + return signature.resolvedReturnType; + } + + function getReturnTypeFromAnnotation(declaration: SignatureDeclaration | JSDocSignature) { + if (declaration.kind === SyntaxKind.Constructor) { + return getDeclaredTypeOfClassOrInterface(getMergedSymbol((declaration.parent as ClassDeclaration).symbol)); + } + const typeNode = getEffectiveReturnTypeNode(declaration); + if (isJSDocSignature(declaration)) { + const root = getJSDocRoot(declaration); + if (root && isConstructorDeclaration(root.parent) && !typeNode) { + return getDeclaredTypeOfClassOrInterface(getMergedSymbol((root.parent.parent as ClassDeclaration).symbol)); + } + } + if (isJSDocConstructSignature(declaration)) { + return getTypeFromTypeNode((declaration.parameters[0] as ParameterDeclaration).type!); // TODO: GH#18217 + } + if (typeNode) { + return getTypeFromTypeNode(typeNode); + } + if (declaration.kind === SyntaxKind.GetAccessor && hasBindableName(declaration)) { + const jsDocType = isInJSFile(declaration) && getTypeForDeclarationFromJSDocComment(declaration); + if (jsDocType) { + return jsDocType; + } + const setter = getDeclarationOfKind(getSymbolOfDeclaration(declaration), SyntaxKind.SetAccessor); + const setterType = getAnnotatedAccessorType(setter); + if (setterType) { + return setterType; + } + } + return getReturnTypeOfTypeTag(declaration); + } + + function isResolvingReturnTypeOfSignature(signature: Signature): boolean { + return signature.compositeSignatures && some(signature.compositeSignatures, isResolvingReturnTypeOfSignature) || + !signature.resolvedReturnType && findResolutionCycleStartIndex(signature, TypeSystemPropertyName.ResolvedReturnType) >= 0; + } + + function getRestTypeOfSignature(signature: Signature): Type { + return tryGetRestTypeOfSignature(signature) || anyType; + } + + function tryGetRestTypeOfSignature(signature: Signature): Type | undefined { + if (signatureHasRestParameter(signature)) { + const sigRestType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + const restType = isTupleType(sigRestType) ? getRestTypeOfTupleType(sigRestType) : sigRestType; + return restType && getIndexTypeOfType(restType, numberType); + } + return undefined; + } + + function getSignatureInstantiation(signature: Signature, typeArguments: readonly Type[] | undefined, isJavascript: boolean, inferredTypeParameters?: readonly TypeParameter[]): Signature { + const instantiatedSignature = getSignatureInstantiationWithoutFillingInTypeArguments(signature, fillMissingTypeArguments(typeArguments, signature.typeParameters, getMinTypeArgumentCount(signature.typeParameters), isJavascript)); + if (inferredTypeParameters) { + const returnSignature = getSingleCallOrConstructSignature(getReturnTypeOfSignature(instantiatedSignature)); + if (returnSignature) { + const newReturnSignature = cloneSignature(returnSignature); + newReturnSignature.typeParameters = inferredTypeParameters; + const newInstantiatedSignature = cloneSignature(instantiatedSignature); + newInstantiatedSignature.resolvedReturnType = getOrCreateTypeFromSignature(newReturnSignature); + return newInstantiatedSignature; + } + } + return instantiatedSignature; + } + + function getSignatureInstantiationWithoutFillingInTypeArguments(signature: Signature, typeArguments: readonly Type[] | undefined): Signature { + const instantiations = signature.instantiations || (signature.instantiations = new Map()); + const id = getTypeListId(typeArguments); + let instantiation = instantiations.get(id); + if (!instantiation) { + instantiations.set(id, instantiation = createSignatureInstantiation(signature, typeArguments)); + } + return instantiation; + } + + function createSignatureInstantiation(signature: Signature, typeArguments: readonly Type[] | undefined): Signature { + return instantiateSignature(signature, createSignatureTypeMapper(signature, typeArguments), /*eraseTypeParameters*/ true); + } + + function createSignatureTypeMapper(signature: Signature, typeArguments: readonly Type[] | undefined): TypeMapper { + return createTypeMapper(signature.typeParameters!, typeArguments); + } + + function getErasedSignature(signature: Signature): Signature { + return signature.typeParameters ? + signature.erasedSignatureCache || (signature.erasedSignatureCache = createErasedSignature(signature)) : + signature; + } + + function createErasedSignature(signature: Signature) { + // Create an instantiation of the signature where all type arguments are the any type. + return instantiateSignature(signature, createTypeEraser(signature.typeParameters!), /*eraseTypeParameters*/ true); + } + + function getCanonicalSignature(signature: Signature): Signature { + return signature.typeParameters ? + signature.canonicalSignatureCache || (signature.canonicalSignatureCache = createCanonicalSignature(signature)) : + signature; + } + + function createCanonicalSignature(signature: Signature) { + // Create an instantiation of the signature where each unconstrained type parameter is replaced with + // its original. When a generic class or interface is instantiated, each generic method in the class or + // interface is instantiated with a fresh set of cloned type parameters (which we need to handle scenarios + // where different generations of the same type parameter are in scope). This leads to a lot of new type + // identities, and potentially a lot of work comparing those identities, so here we create an instantiation + // that uses the original type identities for all unconstrained type parameters. + return getSignatureInstantiation( + signature, + map(signature.typeParameters, tp => tp.target && !getConstraintOfTypeParameter(tp.target) ? tp.target : tp), + isInJSFile(signature.declaration), + ); + } + + function getImplementationSignature(signature: Signature) { + return signature.typeParameters ? + signature.implementationSignatureCache ||= createImplementationSignature(signature) : + signature; + } + + function createImplementationSignature(signature: Signature) { + return signature.typeParameters ? instantiateSignature(signature, createTypeMapper([], [])) : signature; + } + + function getBaseSignature(signature: Signature) { + const typeParameters = signature.typeParameters; + if (typeParameters) { + if (signature.baseSignatureCache) { + return signature.baseSignatureCache; + } + const typeEraser = createTypeEraser(typeParameters); + const baseConstraintMapper = createTypeMapper(typeParameters, map(typeParameters, tp => getConstraintOfTypeParameter(tp) || unknownType)); + let baseConstraints: readonly Type[] = map(typeParameters, tp => instantiateType(tp, baseConstraintMapper) || unknownType); + // Run N type params thru the immediate constraint mapper up to N times + // This way any noncircular interdependent type parameters are definitely resolved to their external dependencies + for (let i = 0; i < typeParameters.length - 1; i++) { + baseConstraints = instantiateTypes(baseConstraints, baseConstraintMapper); + } + // and then apply a type eraser to remove any remaining circularly dependent type parameters + baseConstraints = instantiateTypes(baseConstraints, typeEraser); + return signature.baseSignatureCache = instantiateSignature(signature, createTypeMapper(typeParameters, baseConstraints), /*eraseTypeParameters*/ true); + } + return signature; + } + + function getOrCreateTypeFromSignature(signature: Signature, outerTypeParameters?: TypeParameter[]): ObjectType { + // There are two ways to declare a construct signature, one is by declaring a class constructor + // using the constructor keyword, and the other is declaring a bare construct signature in an + // object type literal or interface (using the new keyword). Each way of declaring a constructor + // will result in a different declaration kind. + if (!signature.isolatedSignatureType) { + const kind = signature.declaration?.kind; + + // If declaration is undefined, it is likely to be the signature of the default constructor. + const isConstructor = kind === undefined || kind === SyntaxKind.Constructor || kind === SyntaxKind.ConstructSignature || kind === SyntaxKind.ConstructorType; + + // The type must have a symbol with a `Function` flag and a declaration in order to be correctly flagged as possibly containing + // type variables by `couldContainTypeVariables` + const type = createObjectType(ObjectFlags.Anonymous | ObjectFlags.SingleSignatureType, createSymbol(SymbolFlags.Function, InternalSymbolName.Function)) as SingleSignatureType; + if (signature.declaration && !nodeIsSynthesized(signature.declaration)) { // skip synthetic declarations - keeping those around could be bad, since they lack a parent pointer + type.symbol.declarations = [signature.declaration]; + type.symbol.valueDeclaration = signature.declaration; + } + outerTypeParameters ||= signature.declaration && getOuterTypeParameters(signature.declaration, /*includeThisTypes*/ true); + type.outerTypeParameters = outerTypeParameters; + + type.members = emptySymbols; + type.properties = emptyArray; + type.callSignatures = !isConstructor ? [signature] : emptyArray; + type.constructSignatures = isConstructor ? [signature] : emptyArray; + type.indexInfos = emptyArray; + signature.isolatedSignatureType = type; + } + + return signature.isolatedSignatureType; + } + + function getIndexSymbol(symbol: Symbol): Symbol | undefined { + return symbol.members ? getIndexSymbolFromSymbolTable(symbol.members) : undefined; + } + + function getIndexSymbolFromSymbolTable(symbolTable: SymbolTable): Symbol | undefined { + return symbolTable.get(InternalSymbolName.Index); + } + + function createIndexInfo(keyType: Type, type: Type, isReadonly: boolean, declaration?: IndexSignatureDeclaration): IndexInfo { + return { keyType, type, isReadonly, declaration }; + } + + function getIndexInfosOfSymbol(symbol: Symbol): IndexInfo[] { + const indexSymbol = getIndexSymbol(symbol); + return indexSymbol ? getIndexInfosOfIndexSymbol(indexSymbol) : emptyArray; + } + + function getIndexInfosOfIndexSymbol(indexSymbol: Symbol): IndexInfo[] { + if (indexSymbol.declarations) { + const indexInfos: IndexInfo[] = []; + for (const declaration of (indexSymbol.declarations as IndexSignatureDeclaration[])) { + if (declaration.parameters.length === 1) { + const parameter = declaration.parameters[0]; + if (parameter.type) { + forEachType(getTypeFromTypeNode(parameter.type), keyType => { + if (isValidIndexKeyType(keyType) && !findIndexInfo(indexInfos, keyType)) { + indexInfos.push(createIndexInfo(keyType, declaration.type ? getTypeFromTypeNode(declaration.type) : anyType, hasEffectiveModifier(declaration, ModifierFlags.Readonly), declaration)); + } + }); + } + } + } + return indexInfos; + } + return emptyArray; + } + + function isValidIndexKeyType(type: Type): boolean { + return !!(type.flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.ESSymbol)) || isPatternLiteralType(type) || + !!(type.flags & TypeFlags.Intersection) && !isGenericType(type) && some((type as IntersectionType).types, isValidIndexKeyType); + } + + function getConstraintDeclaration(type: TypeParameter): TypeNode | undefined { + return mapDefined(filter(type.symbol && type.symbol.declarations, isTypeParameterDeclaration), getEffectiveConstraintOfTypeParameter)[0]; + } + + function getInferredTypeParameterConstraint(typeParameter: TypeParameter, omitTypeReferences?: boolean) { + let inferences: Type[] | undefined; + if (typeParameter.symbol?.declarations) { + for (const declaration of typeParameter.symbol.declarations) { + if (declaration.parent.kind === SyntaxKind.InferType) { + // When an 'infer T' declaration is immediately contained in a type reference node + // (such as 'Foo'), T's constraint is inferred from the constraint of the + // corresponding type parameter in 'Foo'. When multiple 'infer T' declarations are + // present, we form an intersection of the inferred constraint types. + const [childTypeParameter = declaration.parent, grandParent] = walkUpParenthesizedTypesAndGetParentAndChild(declaration.parent.parent); + if (grandParent.kind === SyntaxKind.TypeReference && !omitTypeReferences) { + const typeReference = grandParent as TypeReferenceNode; + const typeParameters = getTypeParametersForTypeReferenceOrImport(typeReference); + if (typeParameters) { + const index = typeReference.typeArguments!.indexOf(childTypeParameter as TypeNode); + if (index < typeParameters.length) { + const declaredConstraint = getConstraintOfTypeParameter(typeParameters[index]); + if (declaredConstraint) { + // Type parameter constraints can reference other type parameters so + // constraints need to be instantiated. If instantiation produces the + // type parameter itself, we discard that inference. For example, in + // type Foo = [T, U]; + // type Bar = T extends Foo ? Foo : T; + // the instantiated constraint for U is X, so we discard that inference. + const mapper = makeDeferredTypeMapper( + typeParameters, + typeParameters.map((_, index) => () => { + return getEffectiveTypeArgumentAtIndex(typeReference, typeParameters, index); + }), + ); + const constraint = instantiateType(declaredConstraint, mapper); + if (constraint !== typeParameter) { + inferences = append(inferences, constraint); + } + } + } + } + } + // When an 'infer T' declaration is immediately contained in a rest parameter declaration, a rest type + // or a named rest tuple element, we infer an 'unknown[]' constraint. + else if ( + grandParent.kind === SyntaxKind.Parameter && (grandParent as ParameterDeclaration).dotDotDotToken || + grandParent.kind === SyntaxKind.RestType || + grandParent.kind === SyntaxKind.NamedTupleMember && (grandParent as NamedTupleMember).dotDotDotToken + ) { + inferences = append(inferences, createArrayType(unknownType)); + } + // When an 'infer T' declaration is immediately contained in a string template type, we infer a 'string' + // constraint. + else if (grandParent.kind === SyntaxKind.TemplateLiteralTypeSpan) { + inferences = append(inferences, stringType); + } + // When an 'infer T' declaration is in the constraint position of a mapped type, we infer a 'keyof any' + // constraint. + else if (grandParent.kind === SyntaxKind.TypeParameter && grandParent.parent.kind === SyntaxKind.MappedType) { + inferences = append(inferences, stringNumberSymbolType); + } + // When an 'infer T' declaration is the template of a mapped type, and that mapped type is the extends + // clause of a conditional whose check type is also a mapped type, give it a constraint equal to the template + // of the check type's mapped type + else if ( + grandParent.kind === SyntaxKind.MappedType && (grandParent as MappedTypeNode).type && + skipParentheses((grandParent as MappedTypeNode).type!) === declaration.parent && grandParent.parent.kind === SyntaxKind.ConditionalType && + (grandParent.parent as ConditionalTypeNode).extendsType === grandParent && (grandParent.parent as ConditionalTypeNode).checkType.kind === SyntaxKind.MappedType && + ((grandParent.parent as ConditionalTypeNode).checkType as MappedTypeNode).type + ) { + const checkMappedType = (grandParent.parent as ConditionalTypeNode).checkType as MappedTypeNode; + const nodeType = getTypeFromTypeNode(checkMappedType.type!); + inferences = append(inferences, instantiateType(nodeType, makeUnaryTypeMapper(getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(checkMappedType.typeParameter)), checkMappedType.typeParameter.constraint ? getTypeFromTypeNode(checkMappedType.typeParameter.constraint) : stringNumberSymbolType))); + } + } + } + } + return inferences && getIntersectionType(inferences); + } + + /** This is a worker function. Use getConstraintOfTypeParameter which guards against circular constraints. */ + function getConstraintFromTypeParameter(typeParameter: TypeParameter): Type | undefined { + if (!typeParameter.constraint) { + if (typeParameter.target) { + const targetConstraint = getConstraintOfTypeParameter(typeParameter.target); + typeParameter.constraint = targetConstraint ? instantiateType(targetConstraint, typeParameter.mapper) : noConstraintType; + } + else { + const constraintDeclaration = getConstraintDeclaration(typeParameter); + if (!constraintDeclaration) { + typeParameter.constraint = getInferredTypeParameterConstraint(typeParameter) || noConstraintType; + } + else { + let type = getTypeFromTypeNode(constraintDeclaration); + if (type.flags & TypeFlags.Any && !isErrorType(type)) { // Allow errorType to propegate to keep downstream errors suppressed + // use stringNumberSymbolType as the base constraint for mapped type key constraints (unknown isn;t assignable to that, but `any` was), + // use unknown otherwise + type = constraintDeclaration.parent.parent.kind === SyntaxKind.MappedType ? stringNumberSymbolType : unknownType; + } + typeParameter.constraint = type; + } + } + } + return typeParameter.constraint === noConstraintType ? undefined : typeParameter.constraint; + } + + function getParentSymbolOfTypeParameter(typeParameter: TypeParameter): Symbol | undefined { + const tp = getDeclarationOfKind(typeParameter.symbol, SyntaxKind.TypeParameter)!; + const host = isJSDocTemplateTag(tp.parent) ? getEffectiveContainerForJSDocTemplateTag(tp.parent) : tp.parent; + return host && getSymbolOfNode(host); + } + + function getTypeListId(types: readonly Type[] | undefined) { + let result = ""; + if (types) { + const length = types.length; + let i = 0; + while (i < length) { + const startId = types[i].id; + let count = 1; + while (i + count < length && types[i + count].id === startId + count) { + count++; + } + if (result.length) { + result += ","; + } + result += startId; + if (count > 1) { + result += ":" + count; + } + i += count; + } + } + return result; + } + + function getAliasId(aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { + return aliasSymbol ? `@${getSymbolId(aliasSymbol)}` + (aliasTypeArguments ? `:${getTypeListId(aliasTypeArguments)}` : "") : ""; + } + + // This function is used to propagate certain flags when creating new object type references and union types. + // It is only necessary to do so if a constituent type might be the undefined type, the null type, the type + // of an object literal or a non-inferrable type. This is because there are operations in the type checker + // that care about the presence of such types at arbitrary depth in a containing type. + function getPropagatingFlagsOfTypes(types: readonly Type[], excludeKinds?: TypeFlags): ObjectFlags { + let result: ObjectFlags = 0; + for (const type of types) { + if (excludeKinds === undefined || !(type.flags & excludeKinds)) { + result |= getObjectFlags(type); + } + } + return result & ObjectFlags.PropagatingFlags; + } + + function tryCreateTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined): Type { + if (some(typeArguments) && target === emptyGenericType) { + return unknownType; + } + + return createTypeReference(target, typeArguments); + } + + function createTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined): TypeReference { + const id = getTypeListId(typeArguments); + let type = target.instantiations.get(id); + if (!type) { + type = createObjectType(ObjectFlags.Reference, target.symbol) as TypeReference; + target.instantiations.set(id, type); + type.objectFlags |= typeArguments ? getPropagatingFlagsOfTypes(typeArguments) : 0; + type.target = target; + type.resolvedTypeArguments = typeArguments; + } + return type; + } + + function cloneTypeReference(source: TypeReference): TypeReference { + const type = createTypeWithSymbol(source.flags, source.symbol) as TypeReference; + type.objectFlags = source.objectFlags; + type.target = source.target; + type.resolvedTypeArguments = source.resolvedTypeArguments; + return type; + } + + function createDeferredTypeReference(target: GenericType, node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, mapper?: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): DeferredTypeReference { + if (!aliasSymbol) { + aliasSymbol = getAliasSymbolForTypeNode(node); + const localAliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); + aliasTypeArguments = mapper ? instantiateTypes(localAliasTypeArguments, mapper) : localAliasTypeArguments; + } + const type = createObjectType(ObjectFlags.Reference, target.symbol) as DeferredTypeReference; + type.target = target; + type.node = node; + type.mapper = mapper; + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = aliasTypeArguments; + return type; + } + + function getTypeArguments(type: TypeReference): readonly Type[] { + if (!type.resolvedTypeArguments) { + if (!pushTypeResolution(type, TypeSystemPropertyName.ResolvedTypeArguments)) { + return type.target.localTypeParameters?.map(() => errorType) || emptyArray; + } + const node = type.node; + const typeArguments = !node ? emptyArray : + node.kind === SyntaxKind.TypeReference ? concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters!)) : + node.kind === SyntaxKind.ArrayType ? [getTypeFromTypeNode(node.elementType)] : + map(node.elements, getTypeFromTypeNode); + if (popTypeResolution()) { + type.resolvedTypeArguments ??= type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments; + } + else { + type.resolvedTypeArguments ??= type.target.localTypeParameters?.map(() => errorType) || emptyArray; + error( + type.node || currentNode, + type.target.symbol ? Diagnostics.Type_arguments_for_0_circularly_reference_themselves : Diagnostics.Tuple_type_arguments_circularly_reference_themselves, + type.target.symbol && symbolToString(type.target.symbol), + ); + } + } + return type.resolvedTypeArguments; + } + + function getTypeReferenceArity(type: TypeReference): number { + return length(type.target.typeParameters); + } + + /** + * Get type from type-reference that reference to class or interface + */ + function getTypeFromClassOrInterfaceReference(node: NodeWithTypeArguments, symbol: Symbol): Type { + const type = getDeclaredTypeOfSymbol(getMergedSymbol(symbol)) as InterfaceType; + const typeParameters = type.localTypeParameters; + if (typeParameters) { + const numTypeArguments = length(node.typeArguments); + const minTypeArgumentCount = getMinTypeArgumentCount(typeParameters); + const isJs = isInJSFile(node); + const isJsImplicitAny = !noImplicitAny && isJs; + if (!isJsImplicitAny && (numTypeArguments < minTypeArgumentCount || numTypeArguments > typeParameters.length)) { + const missingAugmentsTag = isJs && isExpressionWithTypeArguments(node) && !isJSDocAugmentsTag(node.parent); + const diag = minTypeArgumentCount === typeParameters.length ? + missingAugmentsTag ? + Diagnostics.Expected_0_type_arguments_provide_these_with_an_extends_tag : + Diagnostics.Generic_type_0_requires_1_type_argument_s : + missingAugmentsTag ? + Diagnostics.Expected_0_1_type_arguments_provide_these_with_an_extends_tag : + Diagnostics.Generic_type_0_requires_between_1_and_2_type_arguments; + + const typeStr = typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType); + error(node, diag, typeStr, minTypeArgumentCount, typeParameters.length); + if (!isJs) { + // TODO: Adopt same permissive behavior in TS as in JS to reduce follow-on editing experience failures (requires editing fillMissingTypeArguments) + return errorType; + } + } + if (node.kind === SyntaxKind.TypeReference && isDeferredTypeReferenceNode(node as TypeReferenceNode, length(node.typeArguments) !== typeParameters.length)) { + return createDeferredTypeReference(type as GenericType, node as TypeReferenceNode, /*mapper*/ undefined); + } + // In a type reference, the outer type parameters of the referenced class or interface are automatically + // supplied as type arguments and the type reference only specifies arguments for the local type parameters + // of the class or interface. + const typeArguments = concatenate(type.outerTypeParameters, fillMissingTypeArguments(typeArgumentsFromTypeReferenceNode(node), typeParameters, minTypeArgumentCount, isJs)); + return createTypeReference(type as GenericType, typeArguments); + } + return checkNoTypeArguments(node, symbol) ? type : errorType; + } + + function getTypeAliasInstantiation(symbol: Symbol, typeArguments: readonly Type[] | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + const type = getDeclaredTypeOfSymbol(symbol); + if (type === intrinsicMarkerType) { + const typeKind = intrinsicTypeKinds.get(symbol.escapedName as string); + if (typeKind !== undefined && typeArguments && typeArguments.length === 1) { + return typeKind === IntrinsicTypeKind.NoInfer ? getNoInferType(typeArguments[0]) : getStringMappingType(symbol, typeArguments[0]); + } + } + const links = getSymbolLinks(symbol); + const typeParameters = links.typeParameters!; + const id = getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments); + let instantiation = links.instantiations!.get(id); + if (!instantiation) { + links.instantiations!.set(id, instantiation = instantiateTypeWithAlias(type, createTypeMapper(typeParameters, fillMissingTypeArguments(typeArguments, typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(symbol.valueDeclaration))), aliasSymbol, aliasTypeArguments)); + } + return instantiation; + } + + /** + * Get type from reference to type alias. When a type alias is generic, the declared type of the type alias may include + * references to the type parameters of the alias. We replace those with the actual type arguments by instantiating the + * declared type. Instantiations are cached using the type identities of the type arguments as the key. + */ + function getTypeFromTypeAliasReference(node: NodeWithTypeArguments, symbol: Symbol): Type { + if (getCheckFlags(symbol) & CheckFlags.Unresolved) { + const typeArguments = typeArgumentsFromTypeReferenceNode(node); + const id = getAliasId(symbol, typeArguments); + let errorType = errorTypes.get(id); + if (!errorType) { + errorType = createIntrinsicType(TypeFlags.Any, "error", /*objectFlags*/ undefined, `alias ${id}`); + errorType.aliasSymbol = symbol; + errorType.aliasTypeArguments = typeArguments; + errorTypes.set(id, errorType); + } + return errorType; + } + const type = getDeclaredTypeOfSymbol(symbol); + const typeParameters = getSymbolLinks(symbol).typeParameters; + if (typeParameters) { + const numTypeArguments = length(node.typeArguments); + const minTypeArgumentCount = getMinTypeArgumentCount(typeParameters); + if (numTypeArguments < minTypeArgumentCount || numTypeArguments > typeParameters.length) { + error( + node, + minTypeArgumentCount === typeParameters.length ? + Diagnostics.Generic_type_0_requires_1_type_argument_s : + Diagnostics.Generic_type_0_requires_between_1_and_2_type_arguments, + symbolToString(symbol), + minTypeArgumentCount, + typeParameters.length, + ); + return errorType; + } + // We refrain from associating a local type alias with an instantiation of a top-level type alias + // because the local alias may end up being referenced in an inferred return type where it is not + // accessible--which in turn may lead to a large structural expansion of the type when generating + // a .d.ts file. See #43622 for an example. + const aliasSymbol = getAliasSymbolForTypeNode(node); + let newAliasSymbol = aliasSymbol && (isLocalTypeAlias(symbol) || !isLocalTypeAlias(aliasSymbol)) ? aliasSymbol : undefined; + let aliasTypeArguments: Type[] | undefined; + if (newAliasSymbol) { + aliasTypeArguments = getTypeArgumentsForAliasSymbol(newAliasSymbol); + } + else if (isTypeReferenceType(node)) { + const aliasSymbol = resolveTypeReferenceName(node, SymbolFlags.Alias, /*ignoreErrors*/ true); + // refers to an alias import/export/reexport - by making sure we use the target as an aliasSymbol, + // we ensure the exported symbol is used to refer to the type when it's reserialized later + if (aliasSymbol && aliasSymbol !== unknownSymbol) { + const resolved = resolveAlias(aliasSymbol); + if (resolved && resolved.flags & SymbolFlags.TypeAlias) { + newAliasSymbol = resolved; + aliasTypeArguments = typeArgumentsFromTypeReferenceNode(node) || (typeParameters ? [] : undefined); + } + } + } + return getTypeAliasInstantiation(symbol, typeArgumentsFromTypeReferenceNode(node), newAliasSymbol, aliasTypeArguments); + } + return checkNoTypeArguments(node, symbol) ? type : errorType; + } + + function isLocalTypeAlias(symbol: Symbol) { + const declaration = symbol.declarations?.find(isTypeAlias); + return !!(declaration && getContainingFunction(declaration)); + } + + function getTypeReferenceName(node: TypeReferenceType): EntityNameOrEntityNameExpression | undefined { + switch (node.kind) { + case SyntaxKind.TypeReference: + return node.typeName; + case SyntaxKind.ExpressionWithTypeArguments: + // We only support expressions that are simple qualified names. For other + // expressions this produces undefined. + const expr = node.expression; + if (isEntityNameExpression(expr)) { + return expr; + } + // fall through; + } + + return undefined; + } + + function getSymbolPath(symbol: Symbol): string { + return symbol.parent ? `${getSymbolPath(symbol.parent)}.${symbol.escapedName}` : symbol.escapedName as string; + } + + function getUnresolvedSymbolForEntityName(name: EntityNameOrEntityNameExpression) { + const identifier = name.kind === SyntaxKind.QualifiedName ? name.right : + name.kind === SyntaxKind.PropertyAccessExpression ? name.name : + name; + const text = identifier.escapedText; + if (text) { + const parentSymbol = name.kind === SyntaxKind.QualifiedName ? getUnresolvedSymbolForEntityName(name.left) : + name.kind === SyntaxKind.PropertyAccessExpression ? getUnresolvedSymbolForEntityName(name.expression) : + undefined; + const path = parentSymbol ? `${getSymbolPath(parentSymbol)}.${text}` : text as string; + let result = unresolvedSymbols.get(path); + if (!result) { + unresolvedSymbols.set(path, result = createSymbol(SymbolFlags.TypeAlias, text, CheckFlags.Unresolved)); + result.parent = parentSymbol; + result.links.declaredType = unresolvedType; + } + return result; + } + return unknownSymbol; + } + + function resolveTypeReferenceName(typeReference: TypeReferenceType, meaning: SymbolFlags, ignoreErrors?: boolean) { + const name = getTypeReferenceName(typeReference); + if (!name) { + return unknownSymbol; + } + const symbol = resolveEntityName(name, meaning, ignoreErrors); + return symbol && symbol !== unknownSymbol ? symbol : + ignoreErrors ? unknownSymbol : getUnresolvedSymbolForEntityName(name); + } + + function getTypeReferenceType(node: NodeWithTypeArguments, symbol: Symbol): Type { + if (symbol === unknownSymbol) { + return errorType; + } + symbol = getExpandoSymbol(symbol) || symbol; + if (symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { + return getTypeFromClassOrInterfaceReference(node, symbol); + } + if (symbol.flags & SymbolFlags.TypeAlias) { + return getTypeFromTypeAliasReference(node, symbol); + } + // Get type from reference to named type that cannot be generic (enum or type parameter) + const res = tryGetDeclaredTypeOfSymbol(symbol); + if (res) { + return checkNoTypeArguments(node, symbol) ? getRegularTypeOfLiteralType(res) : errorType; + } + if (symbol.flags & SymbolFlags.Value && isJSDocTypeReference(node)) { + const jsdocType = getTypeFromJSDocValueReference(node, symbol); + if (jsdocType) { + return jsdocType; + } + else { + // Resolve the type reference as a Type for the purpose of reporting errors. + resolveTypeReferenceName(node, SymbolFlags.Type); + return getTypeOfSymbol(symbol); + } + } + return errorType; + } + + /** + * A JSdoc TypeReference may be to a value, but resolve it as a type anyway. + * Example: import('./b').ConstructorFunction + */ + function getTypeFromJSDocValueReference(node: NodeWithTypeArguments, symbol: Symbol): Type | undefined { + const links = getNodeLinks(node); + if (!links.resolvedJSDocType) { + const valueType = getTypeOfSymbol(symbol); + let typeType = valueType; + if (symbol.valueDeclaration) { + const isImportTypeWithQualifier = node.kind === SyntaxKind.ImportType && (node as ImportTypeNode).qualifier; + // valueType might not have a symbol, eg, {import('./b').STRING_LITERAL} + if (valueType.symbol && valueType.symbol !== symbol && isImportTypeWithQualifier) { + typeType = getTypeReferenceType(node, valueType.symbol); + } + } + links.resolvedJSDocType = typeType; + } + return links.resolvedJSDocType; + } + + function getNoInferType(type: Type) { + return isNoInferTargetType(type) ? getOrCreateSubstitutionType(type, unknownType) : type; + } + + function isNoInferTargetType(type: Type): boolean { + // This is effectively a more conservative and predictable form of couldContainTypeVariables. We want to + // preserve NoInfer only for types that could contain type variables, but we don't want to exhaustively + // examine all object type members. + return !!(type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, isNoInferTargetType) || + type.flags & TypeFlags.Substitution && !isNoInferType(type) && isNoInferTargetType((type as SubstitutionType).baseType) || + type.flags & TypeFlags.Object && !isEmptyAnonymousObjectType(type) || + type.flags & (TypeFlags.Instantiable & ~TypeFlags.Substitution) && !isPatternLiteralType(type)); + } + + function isNoInferType(type: Type) { + // A NoInfer type is represented as a substitution type with a TypeFlags.Unknown constraint. + return !!(type.flags & TypeFlags.Substitution && (type as SubstitutionType).constraint.flags & TypeFlags.Unknown); + } + + function getSubstitutionType(baseType: Type, constraint: Type) { + return constraint.flags & TypeFlags.AnyOrUnknown || constraint === baseType || baseType.flags & TypeFlags.Any ? + baseType : + getOrCreateSubstitutionType(baseType, constraint); + } + + function getOrCreateSubstitutionType(baseType: Type, constraint: Type) { + const id = `${getTypeId(baseType)}>${getTypeId(constraint)}`; + const cached = substitutionTypes.get(id); + if (cached) { + return cached; + } + const result = createType(TypeFlags.Substitution) as SubstitutionType; + result.baseType = baseType; + result.constraint = constraint; + substitutionTypes.set(id, result); + return result; + } + + function getSubstitutionIntersection(substitutionType: SubstitutionType) { + return isNoInferType(substitutionType) ? substitutionType.baseType : getIntersectionType([substitutionType.constraint, substitutionType.baseType]); + } + + function isUnaryTupleTypeNode(node: TypeNode) { + return node.kind === SyntaxKind.TupleType && (node as TupleTypeNode).elements.length === 1; + } + + function getImpliedConstraint(type: Type, checkNode: TypeNode, extendsNode: TypeNode): Type | undefined { + return isUnaryTupleTypeNode(checkNode) && isUnaryTupleTypeNode(extendsNode) ? getImpliedConstraint(type, (checkNode as TupleTypeNode).elements[0], (extendsNode as TupleTypeNode).elements[0]) : + getActualTypeVariable(getTypeFromTypeNode(checkNode)) === getActualTypeVariable(type) ? getTypeFromTypeNode(extendsNode) : + undefined; + } + + function getConditionalFlowTypeOfType(type: Type, node: Node) { + let constraints: Type[] | undefined; + let covariant = true; + while (node && !isStatement(node) && node.kind !== SyntaxKind.JSDoc) { + const parent = node.parent; + // only consider variance flipped by parameter locations - `keyof` types would usually be considered variance inverting, but + // often get used in indexed accesses where they behave sortof invariantly, but our checking is lax + if (parent.kind === SyntaxKind.Parameter) { + covariant = !covariant; + } + // Always substitute on type parameters, regardless of variance, since even + // in contravariant positions, they may rely on substituted constraints to be valid + if ((covariant || type.flags & TypeFlags.TypeVariable) && parent.kind === SyntaxKind.ConditionalType && node === (parent as ConditionalTypeNode).trueType) { + const constraint = getImpliedConstraint(type, (parent as ConditionalTypeNode).checkType, (parent as ConditionalTypeNode).extendsType); + if (constraint) { + constraints = append(constraints, constraint); + } + } + // Given a homomorphic mapped type { [K in keyof T]: XXX }, where T is constrained to an array or tuple type, in the + // template type XXX, K has an added constraint of number | `${number}`. + else if (type.flags & TypeFlags.TypeParameter && parent.kind === SyntaxKind.MappedType && !(parent as MappedTypeNode).nameType && node === (parent as MappedTypeNode).type) { + const mappedType = getTypeFromTypeNode(parent as TypeNode) as MappedType; + if (getTypeParameterFromMappedType(mappedType) === getActualTypeVariable(type)) { + const typeParameter = getHomomorphicTypeVariable(mappedType); + if (typeParameter) { + const constraint = getConstraintOfTypeParameter(typeParameter); + if (constraint && everyType(constraint, isArrayOrTupleType)) { + constraints = append(constraints, getUnionType([numberType, numericStringType])); + } + } + } + } + node = parent; + } + return constraints ? getSubstitutionType(type, getIntersectionType(constraints)) : type; + } + + function isJSDocTypeReference(node: Node): node is TypeReferenceNode { + return !!(node.flags & NodeFlags.JSDoc) && (node.kind === SyntaxKind.TypeReference || node.kind === SyntaxKind.ImportType); + } + + function checkNoTypeArguments(node: NodeWithTypeArguments, symbol?: Symbol) { + if (node.typeArguments) { + error(node, Diagnostics.Type_0_is_not_generic, symbol ? symbolToString(symbol) : (node as TypeReferenceNode).typeName ? declarationNameToString((node as TypeReferenceNode).typeName) : anon); + return false; + } + return true; + } + + function getIntendedTypeFromJSDocTypeReference(node: TypeReferenceNode): Type | undefined { + if (isIdentifier(node.typeName)) { + const typeArgs = node.typeArguments; + switch (node.typeName.escapedText) { + case "String": + checkNoTypeArguments(node); + return stringType; + case "Number": + checkNoTypeArguments(node); + return numberType; + case "Boolean": + checkNoTypeArguments(node); + return booleanType; + case "Void": + checkNoTypeArguments(node); + return voidType; + case "Undefined": + checkNoTypeArguments(node); + return undefinedType; + case "Null": + checkNoTypeArguments(node); + return nullType; + case "Function": + case "function": + checkNoTypeArguments(node); + return globalFunctionType; + case "array": + return (!typeArgs || !typeArgs.length) && !noImplicitAny ? anyArrayType : undefined; + case "promise": + return (!typeArgs || !typeArgs.length) && !noImplicitAny ? createPromiseType(anyType) : undefined; + case "Object": + if (typeArgs && typeArgs.length === 2) { + if (isJSDocIndexSignature(node)) { + const indexed = getTypeFromTypeNode(typeArgs[0]); + const target = getTypeFromTypeNode(typeArgs[1]); + const indexInfo = indexed === stringType || indexed === numberType ? [createIndexInfo(indexed, target, /*isReadonly*/ false)] : emptyArray; + return createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, indexInfo); + } + return anyType; + } + checkNoTypeArguments(node); + return !noImplicitAny ? anyType : undefined; + } + } + } + + function getTypeFromJSDocNullableTypeNode(node: JSDocNullableType) { + const type = getTypeFromTypeNode(node.type); + return strictNullChecks ? getNullableType(type, TypeFlags.Null) : type; + } + + function getTypeFromTypeReference(node: TypeReferenceType): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + // handle LS queries on the `const` in `x as const` by resolving to the type of `x` + if (isConstTypeReference(node) && isAssertionExpression(node.parent)) { + links.resolvedSymbol = unknownSymbol; + return links.resolvedType = checkExpressionCached(node.parent.expression); + } + let symbol: Symbol | undefined; + let type: Type | undefined; + const meaning = SymbolFlags.Type; + if (isJSDocTypeReference(node)) { + type = getIntendedTypeFromJSDocTypeReference(node); + if (!type) { + symbol = resolveTypeReferenceName(node, meaning, /*ignoreErrors*/ true); + if (symbol === unknownSymbol) { + symbol = resolveTypeReferenceName(node, meaning | SymbolFlags.Value); + } + else { + resolveTypeReferenceName(node, meaning); // Resolve again to mark errors, if any + } + type = getTypeReferenceType(node, symbol); + } + } + if (!type) { + symbol = resolveTypeReferenceName(node, meaning); + type = getTypeReferenceType(node, symbol); + } + // Cache both the resolved symbol and the resolved type. The resolved symbol is needed when we check the + // type reference in checkTypeReferenceNode. + links.resolvedSymbol = symbol; + links.resolvedType = type; + } + return links.resolvedType; + } + + function typeArgumentsFromTypeReferenceNode(node: NodeWithTypeArguments): Type[] | undefined { + return map(node.typeArguments, getTypeFromTypeNode); + } + + function getTypeFromTypeQueryNode(node: TypeQueryNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + // TypeScript 1.0 spec (April 2014): 3.6.3 + // The expression is processed as an identifier expression (section 4.3) + // or property access expression(section 4.10), + // the widened type(section 3.9) of which becomes the result. + const type = checkExpressionWithTypeArguments(node); + links.resolvedType = getRegularTypeOfLiteralType(getWidenedType(type)); + } + return links.resolvedType; + } + + function getTypeOfGlobalSymbol(symbol: Symbol | undefined, arity: number): ObjectType { + function getTypeDeclaration(symbol: Symbol): Declaration | undefined { + const declarations = symbol.declarations; + if (declarations) { + for (const declaration of declarations) { + switch (declaration.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.EnumDeclaration: + return declaration; + } + } + } + } + + if (!symbol) { + return arity ? emptyGenericType : emptyObjectType; + } + const type = getDeclaredTypeOfSymbol(symbol); + if (!(type.flags & TypeFlags.Object)) { + error(getTypeDeclaration(symbol), Diagnostics.Global_type_0_must_be_a_class_or_interface_type, symbolName(symbol)); + return arity ? emptyGenericType : emptyObjectType; + } + if (length((type as InterfaceType).typeParameters) !== arity) { + error(getTypeDeclaration(symbol), Diagnostics.Global_type_0_must_have_1_type_parameter_s, symbolName(symbol), arity); + return arity ? emptyGenericType : emptyObjectType; + } + return type as ObjectType; + } + + function getGlobalValueSymbol(name: __String, reportErrors: boolean): Symbol | undefined { + return getGlobalSymbol(name, SymbolFlags.Value, reportErrors ? Diagnostics.Cannot_find_global_value_0 : undefined); + } + + function getGlobalTypeSymbol(name: __String, reportErrors: boolean): Symbol | undefined { + return getGlobalSymbol(name, SymbolFlags.Type, reportErrors ? Diagnostics.Cannot_find_global_type_0 : undefined); + } + + function getGlobalTypeAliasSymbol(name: __String, arity: number, reportErrors: boolean): Symbol | undefined { + const symbol = getGlobalSymbol(name, SymbolFlags.Type, reportErrors ? Diagnostics.Cannot_find_global_type_0 : undefined); + if (symbol) { + // Resolve the declared type of the symbol. This resolves type parameters for the type + // alias so that we can check arity. + getDeclaredTypeOfSymbol(symbol); + if (length(getSymbolLinks(symbol).typeParameters) !== arity) { + const decl = symbol.declarations && find(symbol.declarations, isTypeAliasDeclaration); + error(decl, Diagnostics.Global_type_0_must_have_1_type_parameter_s, symbolName(symbol), arity); + return undefined; + } + } + return symbol; + } + + function getGlobalSymbol(name: __String, meaning: SymbolFlags, diagnostic: DiagnosticMessage | undefined): Symbol | undefined { + // Don't track references for global symbols anyway, so value if `isReference` is arbitrary + return resolveName(/*location*/ undefined, name, meaning, diagnostic, /*isUse*/ false, /*excludeGlobals*/ false); + } + + function getGlobalType(name: __String, arity: 0, reportErrors: true): ObjectType; + function getGlobalType(name: __String, arity: 0, reportErrors: boolean): ObjectType | undefined; + function getGlobalType(name: __String, arity: number, reportErrors: true): GenericType; + function getGlobalType(name: __String, arity: number, reportErrors: boolean): GenericType | undefined; + function getGlobalType(name: __String, arity: number, reportErrors: boolean): ObjectType | undefined { + const symbol = getGlobalTypeSymbol(name, reportErrors); + return symbol || reportErrors ? getTypeOfGlobalSymbol(symbol, arity) : undefined; + } + + function getGlobalTypedPropertyDescriptorType() { + // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times + return deferredGlobalTypedPropertyDescriptorType ||= getGlobalType("TypedPropertyDescriptor" as __String, /*arity*/ 1, /*reportErrors*/ true) || emptyGenericType; + } + + function getGlobalTemplateStringsArrayType() { + // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times + return deferredGlobalTemplateStringsArrayType ||= getGlobalType("TemplateStringsArray" as __String, /*arity*/ 0, /*reportErrors*/ true) || emptyObjectType; + } + + function getGlobalImportMetaType() { + // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times + return deferredGlobalImportMetaType ||= getGlobalType("ImportMeta" as __String, /*arity*/ 0, /*reportErrors*/ true) || emptyObjectType; + } + + function getGlobalImportMetaExpressionType() { + if (!deferredGlobalImportMetaExpressionType) { + // Create a synthetic type `ImportMetaExpression { meta: MetaProperty }` + const symbol = createSymbol(SymbolFlags.None, "ImportMetaExpression" as __String); + const importMetaType = getGlobalImportMetaType(); + + const metaPropertySymbol = createSymbol(SymbolFlags.Property, "meta" as __String, CheckFlags.Readonly); + metaPropertySymbol.parent = symbol; + metaPropertySymbol.links.type = importMetaType; + + const members = createSymbolTable([metaPropertySymbol]); + symbol.members = members; + + deferredGlobalImportMetaExpressionType = createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + } + return deferredGlobalImportMetaExpressionType; + } + + function getGlobalImportCallOptionsType(reportErrors: boolean) { + return (deferredGlobalImportCallOptionsType ||= getGlobalType("ImportCallOptions" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalImportAttributesType(reportErrors: boolean) { + return (deferredGlobalImportAttributesType ||= getGlobalType("ImportAttributes" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalESSymbolConstructorSymbol(reportErrors: boolean): Symbol | undefined { + return deferredGlobalESSymbolConstructorSymbol ||= getGlobalValueSymbol("Symbol" as __String, reportErrors); + } + + function getGlobalESSymbolConstructorTypeSymbol(reportErrors: boolean): Symbol | undefined { + return deferredGlobalESSymbolConstructorTypeSymbol ||= getGlobalTypeSymbol("SymbolConstructor" as __String, reportErrors); + } + + function getGlobalESSymbolType() { + return (deferredGlobalESSymbolType ||= getGlobalType("Symbol" as __String, /*arity*/ 0, /*reportErrors*/ false)) || emptyObjectType; + } + + function getGlobalPromiseType(reportErrors: boolean) { + return (deferredGlobalPromiseType ||= getGlobalType("Promise" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalPromiseLikeType(reportErrors: boolean) { + return (deferredGlobalPromiseLikeType ||= getGlobalType("PromiseLike" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalPromiseConstructorSymbol(reportErrors: boolean): Symbol | undefined { + return deferredGlobalPromiseConstructorSymbol ||= getGlobalValueSymbol("Promise" as __String, reportErrors); + } + + function getGlobalPromiseConstructorLikeType(reportErrors: boolean) { + return (deferredGlobalPromiseConstructorLikeType ||= getGlobalType("PromiseConstructorLike" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalAsyncIterableType(reportErrors: boolean) { + return (deferredGlobalAsyncIterableType ||= getGlobalType("AsyncIterable" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalAsyncIteratorType(reportErrors: boolean) { + return (deferredGlobalAsyncIteratorType ||= getGlobalType("AsyncIterator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalAsyncIterableIteratorType(reportErrors: boolean) { + return (deferredGlobalAsyncIterableIteratorType ||= getGlobalType("AsyncIterableIterator" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalAsyncGeneratorType(reportErrors: boolean) { + return (deferredGlobalAsyncGeneratorType ||= getGlobalType("AsyncGenerator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalIterableType(reportErrors: boolean) { + return (deferredGlobalIterableType ||= getGlobalType("Iterable" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalIteratorType(reportErrors: boolean) { + return (deferredGlobalIteratorType ||= getGlobalType("Iterator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalIterableIteratorType(reportErrors: boolean) { + return (deferredGlobalIterableIteratorType ||= getGlobalType("IterableIterator" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalGeneratorType(reportErrors: boolean) { + return (deferredGlobalGeneratorType ||= getGlobalType("Generator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalIteratorYieldResultType(reportErrors: boolean) { + return (deferredGlobalIteratorYieldResultType ||= getGlobalType("IteratorYieldResult" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalIteratorReturnResultType(reportErrors: boolean) { + return (deferredGlobalIteratorReturnResultType ||= getGlobalType("IteratorReturnResult" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalDisposableType(reportErrors: boolean) { + return (deferredGlobalDisposableType ||= getGlobalType("Disposable" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalAsyncDisposableType(reportErrors: boolean) { + return (deferredGlobalAsyncDisposableType ||= getGlobalType("AsyncDisposable" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalTypeOrUndefined(name: __String, arity = 0): ObjectType | undefined { + const symbol = getGlobalSymbol(name, SymbolFlags.Type, /*diagnostic*/ undefined); + return symbol && getTypeOfGlobalSymbol(symbol, arity) as GenericType; + } + + function getGlobalExtractSymbol(): Symbol | undefined { + // We always report an error, so cache a result in the event we could not resolve the symbol to prevent reporting it multiple times + deferredGlobalExtractSymbol ||= getGlobalTypeAliasSymbol("Extract" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; + return deferredGlobalExtractSymbol === unknownSymbol ? undefined : deferredGlobalExtractSymbol; + } + + function getGlobalOmitSymbol(): Symbol | undefined { + // We always report an error, so cache a result in the event we could not resolve the symbol to prevent reporting it multiple times + deferredGlobalOmitSymbol ||= getGlobalTypeAliasSymbol("Omit" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; + return deferredGlobalOmitSymbol === unknownSymbol ? undefined : deferredGlobalOmitSymbol; + } + + function getGlobalAwaitedSymbol(reportErrors: boolean): Symbol | undefined { + // Only cache `unknownSymbol` if we are reporting errors so that we don't report the error more than once. + deferredGlobalAwaitedSymbol ||= getGlobalTypeAliasSymbol("Awaited" as __String, /*arity*/ 1, reportErrors) || (reportErrors ? unknownSymbol : undefined); + return deferredGlobalAwaitedSymbol === unknownSymbol ? undefined : deferredGlobalAwaitedSymbol; + } + + function getGlobalBigIntType() { + return (deferredGlobalBigIntType ||= getGlobalType("BigInt" as __String, /*arity*/ 0, /*reportErrors*/ false)) || emptyObjectType; + } + + function getGlobalClassDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassDecoratorContextType ??= getGlobalType("ClassDecoratorContext" as __String, /*arity*/ 1, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassMethodDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassMethodDecoratorContextType ??= getGlobalType("ClassMethodDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassGetterDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassGetterDecoratorContextType ??= getGlobalType("ClassGetterDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassSetterDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassSetterDecoratorContextType ??= getGlobalType("ClassSetterDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassAccessorDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassAccessorDecoratorContextType ??= getGlobalType("ClassAccessorDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassAccessorDecoratorTargetType(reportErrors: boolean) { + return (deferredGlobalClassAccessorDecoratorTargetType ??= getGlobalType("ClassAccessorDecoratorTarget" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassAccessorDecoratorResultType(reportErrors: boolean) { + return (deferredGlobalClassAccessorDecoratorResultType ??= getGlobalType("ClassAccessorDecoratorResult" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassFieldDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassFieldDecoratorContextType ??= getGlobalType("ClassFieldDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalNaNSymbol(): Symbol | undefined { + return (deferredGlobalNaNSymbol ||= getGlobalValueSymbol("NaN" as __String, /*reportErrors*/ false)); + } + + function getGlobalRecordSymbol(): Symbol | undefined { + deferredGlobalRecordSymbol ||= getGlobalTypeAliasSymbol("Record" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; + return deferredGlobalRecordSymbol === unknownSymbol ? undefined : deferredGlobalRecordSymbol; + } + + /** + * Instantiates a global type that is generic with some element type, and returns that instantiation. + */ + function createTypeFromGenericGlobalType(genericGlobalType: GenericType, typeArguments: readonly Type[]): ObjectType { + return genericGlobalType !== emptyGenericType ? createTypeReference(genericGlobalType, typeArguments) : emptyObjectType; + } + + function createTypedPropertyDescriptorType(propertyType: Type): Type { + return createTypeFromGenericGlobalType(getGlobalTypedPropertyDescriptorType(), [propertyType]); + } + + function createIterableType(iteratedType: Type): Type { + return createTypeFromGenericGlobalType(getGlobalIterableType(/*reportErrors*/ true), [iteratedType]); + } + + function createArrayType(elementType: Type, readonly?: boolean): ObjectType { + return createTypeFromGenericGlobalType(readonly ? globalReadonlyArrayType : globalArrayType, [elementType]); + } + + function getTupleElementFlags(node: TypeNode) { + switch (node.kind) { + case SyntaxKind.OptionalType: + return ElementFlags.Optional; + case SyntaxKind.RestType: + return getRestTypeElementFlags(node as RestTypeNode); + case SyntaxKind.NamedTupleMember: + return (node as NamedTupleMember).questionToken ? ElementFlags.Optional : + (node as NamedTupleMember).dotDotDotToken ? getRestTypeElementFlags(node as NamedTupleMember) : + ElementFlags.Required; + default: + return ElementFlags.Required; + } + } + + function getRestTypeElementFlags(node: RestTypeNode | NamedTupleMember) { + return getArrayElementTypeNode(node.type) ? ElementFlags.Rest : ElementFlags.Variadic; + } + + function getArrayOrTupleTargetType(node: ArrayTypeNode | TupleTypeNode): GenericType { + const readonly = isReadonlyTypeOperator(node.parent); + const elementType = getArrayElementTypeNode(node); + if (elementType) { + return readonly ? globalReadonlyArrayType : globalArrayType; + } + const elementFlags = map((node as TupleTypeNode).elements, getTupleElementFlags); + return getTupleTargetType(elementFlags, readonly, map((node as TupleTypeNode).elements, memberIfLabeledElementDeclaration)); + } + + function memberIfLabeledElementDeclaration(member: Node): NamedTupleMember | ParameterDeclaration | undefined { + return isNamedTupleMember(member) || isParameter(member) ? member : undefined; + } + + // Return true if the given type reference node is directly aliased or if it needs to be deferred + // because it is possibly contained in a circular chain of eagerly resolved types. + function isDeferredTypeReferenceNode(node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, hasDefaultTypeArguments?: boolean) { + return !!getAliasSymbolForTypeNode(node) || isResolvedByTypeAlias(node) && ( + node.kind === SyntaxKind.ArrayType ? mayResolveTypeAlias(node.elementType) : + node.kind === SyntaxKind.TupleType ? some(node.elements, mayResolveTypeAlias) : + hasDefaultTypeArguments || some(node.typeArguments, mayResolveTypeAlias) + ); + } + + // Return true when the given node is transitively contained in type constructs that eagerly + // resolve their constituent types. We include SyntaxKind.TypeReference because type arguments + // of type aliases are eagerly resolved. + function isResolvedByTypeAlias(node: Node): boolean { + const parent = node.parent; + switch (parent.kind) { + case SyntaxKind.ParenthesizedType: + case SyntaxKind.NamedTupleMember: + case SyntaxKind.TypeReference: + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + case SyntaxKind.IndexedAccessType: + case SyntaxKind.ConditionalType: + case SyntaxKind.TypeOperator: + case SyntaxKind.ArrayType: + case SyntaxKind.TupleType: + return isResolvedByTypeAlias(parent); + case SyntaxKind.TypeAliasDeclaration: + return true; + } + return false; + } + + // Return true if resolving the given node (i.e. getTypeFromTypeNode) possibly causes resolution + // of a type alias. + function mayResolveTypeAlias(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.TypeReference: + return isJSDocTypeReference(node) || !!(resolveTypeReferenceName(node as TypeReferenceNode, SymbolFlags.Type).flags & SymbolFlags.TypeAlias); + case SyntaxKind.TypeQuery: + return true; + case SyntaxKind.TypeOperator: + return (node as TypeOperatorNode).operator !== SyntaxKind.UniqueKeyword && mayResolveTypeAlias((node as TypeOperatorNode).type); + case SyntaxKind.ParenthesizedType: + case SyntaxKind.OptionalType: + case SyntaxKind.NamedTupleMember: + case SyntaxKind.JSDocOptionalType: + case SyntaxKind.JSDocNullableType: + case SyntaxKind.JSDocNonNullableType: + case SyntaxKind.JSDocTypeExpression: + return mayResolveTypeAlias((node as ParenthesizedTypeNode | OptionalTypeNode | JSDocTypeReferencingNode | NamedTupleMember).type); + case SyntaxKind.RestType: + return (node as RestTypeNode).type.kind !== SyntaxKind.ArrayType || mayResolveTypeAlias(((node as RestTypeNode).type as ArrayTypeNode).elementType); + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + return some((node as UnionOrIntersectionTypeNode).types, mayResolveTypeAlias); + case SyntaxKind.IndexedAccessType: + return mayResolveTypeAlias((node as IndexedAccessTypeNode).objectType) || mayResolveTypeAlias((node as IndexedAccessTypeNode).indexType); + case SyntaxKind.ConditionalType: + return mayResolveTypeAlias((node as ConditionalTypeNode).checkType) || mayResolveTypeAlias((node as ConditionalTypeNode).extendsType) || + mayResolveTypeAlias((node as ConditionalTypeNode).trueType) || mayResolveTypeAlias((node as ConditionalTypeNode).falseType); + } + return false; + } + + function getTypeFromArrayOrTupleTypeNode(node: ArrayTypeNode | TupleTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const target = getArrayOrTupleTargetType(node); + if (target === emptyGenericType) { + links.resolvedType = emptyObjectType; + } + else if (!(node.kind === SyntaxKind.TupleType && some(node.elements, e => !!(getTupleElementFlags(e) & ElementFlags.Variadic))) && isDeferredTypeReferenceNode(node)) { + links.resolvedType = node.kind === SyntaxKind.TupleType && node.elements.length === 0 ? target : + createDeferredTypeReference(target, node, /*mapper*/ undefined); + } + else { + const elementTypes = node.kind === SyntaxKind.ArrayType ? [getTypeFromTypeNode(node.elementType)] : map(node.elements, getTypeFromTypeNode); + links.resolvedType = createNormalizedTypeReference(target, elementTypes); + } + } + return links.resolvedType; + } + + function isReadonlyTypeOperator(node: Node) { + return isTypeOperatorNode(node) && node.operator === SyntaxKind.ReadonlyKeyword; + } + + function createTupleType(elementTypes: readonly Type[], elementFlags?: readonly ElementFlags[], readonly = false, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration | undefined)[] = []) { + const tupleTarget = getTupleTargetType(elementFlags || map(elementTypes, _ => ElementFlags.Required), readonly, namedMemberDeclarations); + return tupleTarget === emptyGenericType ? emptyObjectType : + elementTypes.length ? createNormalizedTypeReference(tupleTarget, elementTypes) : + tupleTarget; + } + + function getTupleTargetType(elementFlags: readonly ElementFlags[], readonly: boolean, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration | undefined)[]): GenericType { + if (elementFlags.length === 1 && elementFlags[0] & ElementFlags.Rest) { + // [...X[]] is equivalent to just X[] + return readonly ? globalReadonlyArrayType : globalArrayType; + } + const key = map(elementFlags, f => f & ElementFlags.Required ? "#" : f & ElementFlags.Optional ? "?" : f & ElementFlags.Rest ? "." : "*").join() + + (readonly ? "R" : "") + + (some(namedMemberDeclarations, node => !!node) ? "," + map(namedMemberDeclarations, node => node ? getNodeId(node) : "_").join(",") : ""); + let type = tupleTypes.get(key); + if (!type) { + tupleTypes.set(key, type = createTupleTargetType(elementFlags, readonly, namedMemberDeclarations)); + } + return type; + } + + // We represent tuple types as type references to synthesized generic interface types created by + // this function. The types are of the form: + // + // interface Tuple extends Array { 0: T0, 1: T1, 2: T2, ... } + // + // Note that the generic type created by this function has no symbol associated with it. The same + // is true for each of the synthesized type parameters. + function createTupleTargetType(elementFlags: readonly ElementFlags[], readonly: boolean, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration | undefined)[]): TupleType { + const arity = elementFlags.length; + const minLength = countWhere(elementFlags, f => !!(f & (ElementFlags.Required | ElementFlags.Variadic))); + let typeParameters: TypeParameter[] | undefined; + const properties: Symbol[] = []; + let combinedFlags = 0 as ElementFlags; + if (arity) { + typeParameters = new Array(arity); + for (let i = 0; i < arity; i++) { + const typeParameter = typeParameters[i] = createTypeParameter(); + const flags = elementFlags[i]; + combinedFlags |= flags; + if (!(combinedFlags & ElementFlags.Variable)) { + const property = createSymbol(SymbolFlags.Property | (flags & ElementFlags.Optional ? SymbolFlags.Optional : 0), "" + i as __String, readonly ? CheckFlags.Readonly : 0); + property.links.tupleLabelDeclaration = namedMemberDeclarations?.[i]; + property.links.type = typeParameter; + properties.push(property); + } + } + } + const fixedLength = properties.length; + const lengthSymbol = createSymbol(SymbolFlags.Property, "length" as __String, readonly ? CheckFlags.Readonly : 0); + if (combinedFlags & ElementFlags.Variable) { + lengthSymbol.links.type = numberType; + } + else { + const literalTypes = []; + for (let i = minLength; i <= arity; i++) literalTypes.push(getNumberLiteralType(i)); + lengthSymbol.links.type = getUnionType(literalTypes); + } + properties.push(lengthSymbol); + const type = createObjectType(ObjectFlags.Tuple | ObjectFlags.Reference) as TupleType & InterfaceTypeWithDeclaredMembers; + type.typeParameters = typeParameters; + type.outerTypeParameters = undefined; + type.localTypeParameters = typeParameters; + type.instantiations = new Map(); + type.instantiations.set(getTypeListId(type.typeParameters), type as GenericType); + type.target = type as GenericType; + type.resolvedTypeArguments = type.typeParameters; + type.thisType = createTypeParameter(); + type.thisType.isThisType = true; + type.thisType.constraint = type; + type.declaredProperties = properties; + type.declaredCallSignatures = emptyArray; + type.declaredConstructSignatures = emptyArray; + type.declaredIndexInfos = emptyArray; + type.elementFlags = elementFlags; + type.minLength = minLength; + type.fixedLength = fixedLength; + type.hasRestElement = !!(combinedFlags & ElementFlags.Variable); + type.combinedFlags = combinedFlags; + type.readonly = readonly; + type.labeledElementDeclarations = namedMemberDeclarations; + return type; + } + + function createNormalizedTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined) { + return target.objectFlags & ObjectFlags.Tuple ? createNormalizedTupleType(target as TupleType, typeArguments!) : createTypeReference(target, typeArguments); + } + + function createNormalizedTupleType(target: TupleType, elementTypes: readonly Type[]): Type { + if (!(target.combinedFlags & ElementFlags.NonRequired)) { + // No need to normalize when we only have regular required elements + return createTypeReference(target, elementTypes); + } + if (target.combinedFlags & ElementFlags.Variadic) { + // Transform [A, ...(X | Y | Z)] into [A, ...X] | [A, ...Y] | [A, ...Z] + const unionIndex = findIndex(elementTypes, (t, i) => !!(target.elementFlags[i] & ElementFlags.Variadic && t.flags & (TypeFlags.Never | TypeFlags.Union))); + if (unionIndex >= 0) { + return checkCrossProductUnion(map(elementTypes, (t, i) => target.elementFlags[i] & ElementFlags.Variadic ? t : unknownType)) ? + mapType(elementTypes[unionIndex], t => createNormalizedTupleType(target, replaceElement(elementTypes, unionIndex, t))) : + errorType; + } + } + // We have optional, rest, or variadic elements that may need normalizing. Normalization ensures that all variadic + // elements are generic and that the tuple type has one of the following layouts, disregarding variadic elements: + // (1) Zero or more required elements, followed by zero or more optional elements, followed by zero or one rest element. + // (2) Zero or more required elements, followed by a rest element, followed by zero or more required elements. + // In either layout, zero or more generic variadic elements may be present at any location. + const expandedTypes: Type[] = []; + const expandedFlags: ElementFlags[] = []; + const expandedDeclarations: (NamedTupleMember | ParameterDeclaration | undefined)[] = []; + let lastRequiredIndex = -1; + let firstRestIndex = -1; + let lastOptionalOrRestIndex = -1; + for (let i = 0; i < elementTypes.length; i++) { + const type = elementTypes[i]; + const flags = target.elementFlags[i]; + if (flags & ElementFlags.Variadic) { + if (type.flags & TypeFlags.Any) { + addElement(type, ElementFlags.Rest, target.labeledElementDeclarations?.[i]); + } + else if (type.flags & TypeFlags.InstantiableNonPrimitive || isGenericMappedType(type)) { + // Generic variadic elements stay as they are. + addElement(type, ElementFlags.Variadic, target.labeledElementDeclarations?.[i]); + } + else if (isTupleType(type)) { + const elements = getElementTypes(type); + if (elements.length + expandedTypes.length >= 10_000) { + error( + currentNode, + isPartOfTypeNode(currentNode!) + ? Diagnostics.Type_produces_a_tuple_type_that_is_too_large_to_represent + : Diagnostics.Expression_produces_a_tuple_type_that_is_too_large_to_represent, + ); + return errorType; + } + // Spread variadic elements with tuple types into the resulting tuple. + forEach(elements, (t, n) => addElement(t, type.target.elementFlags[n], type.target.labeledElementDeclarations?.[n])); + } + else { + // Treat everything else as an array type and create a rest element. + addElement(isArrayLikeType(type) && getIndexTypeOfType(type, numberType) || errorType, ElementFlags.Rest, target.labeledElementDeclarations?.[i]); + } + } + else { + // Copy other element kinds with no change. + addElement(type, flags, target.labeledElementDeclarations?.[i]); + } + } + // Turn optional elements preceding the last required element into required elements + for (let i = 0; i < lastRequiredIndex; i++) { + if (expandedFlags[i] & ElementFlags.Optional) expandedFlags[i] = ElementFlags.Required; + } + if (firstRestIndex >= 0 && firstRestIndex < lastOptionalOrRestIndex) { + // Turn elements between first rest and last optional/rest into a single rest element + expandedTypes[firstRestIndex] = getUnionType(sameMap(expandedTypes.slice(firstRestIndex, lastOptionalOrRestIndex + 1), (t, i) => expandedFlags[firstRestIndex + i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t)); + expandedTypes.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); + expandedFlags.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); + expandedDeclarations.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); + } + const tupleTarget = getTupleTargetType(expandedFlags, target.readonly, expandedDeclarations); + return tupleTarget === emptyGenericType ? emptyObjectType : + expandedFlags.length ? createTypeReference(tupleTarget, expandedTypes) : + tupleTarget; + + function addElement(type: Type, flags: ElementFlags, declaration: NamedTupleMember | ParameterDeclaration | undefined) { + if (flags & ElementFlags.Required) { + lastRequiredIndex = expandedFlags.length; + } + if (flags & ElementFlags.Rest && firstRestIndex < 0) { + firstRestIndex = expandedFlags.length; + } + if (flags & (ElementFlags.Optional | ElementFlags.Rest)) { + lastOptionalOrRestIndex = expandedFlags.length; + } + expandedTypes.push(flags & ElementFlags.Optional ? addOptionality(type, /*isProperty*/ true) : type); + expandedFlags.push(flags); + expandedDeclarations.push(declaration); + } + } + + function sliceTupleType(type: TupleTypeReference, index: number, endSkipCount = 0) { + const target = type.target; + const endIndex = getTypeReferenceArity(type) - endSkipCount; + return index > target.fixedLength ? getRestArrayTypeOfTupleType(type) || createTupleType(emptyArray) : + createTupleType(getTypeArguments(type).slice(index, endIndex), target.elementFlags.slice(index, endIndex), /*readonly*/ false, target.labeledElementDeclarations && target.labeledElementDeclarations.slice(index, endIndex)); + } + + function getKnownKeysOfTupleType(type: TupleTypeReference) { + return getUnionType(append(arrayOf(type.target.fixedLength, i => getStringLiteralType("" + i)), getIndexType(type.target.readonly ? globalReadonlyArrayType : globalArrayType))); + } + + // Return count of starting consecutive tuple elements of the given kind(s) + function getStartElementCount(type: TupleType, flags: ElementFlags) { + const index = findIndex(type.elementFlags, f => !(f & flags)); + return index >= 0 ? index : type.elementFlags.length; + } + + // Return count of ending consecutive tuple elements of the given kind(s) + function getEndElementCount(type: TupleType, flags: ElementFlags) { + return type.elementFlags.length - findLastIndex(type.elementFlags, f => !(f & flags)) - 1; + } + + function getTotalFixedElementCount(type: TupleType) { + return type.fixedLength + getEndElementCount(type, ElementFlags.Fixed); + } + + function getElementTypes(type: TupleTypeReference): readonly Type[] { + const typeArguments = getTypeArguments(type); + const arity = getTypeReferenceArity(type); + return typeArguments.length === arity ? typeArguments : typeArguments.slice(0, arity); + } + + function getTypeFromOptionalTypeNode(node: OptionalTypeNode): Type { + return addOptionality(getTypeFromTypeNode(node.type), /*isProperty*/ true); + } + + function getTypeId(type: Type): TypeId { + return type.id; + } + + function containsType(types: readonly Type[], type: Type): boolean { + return binarySearch(types, type, getTypeId, compareValues) >= 0; + } + + function insertType(types: Type[], type: Type): boolean { + const index = binarySearch(types, type, getTypeId, compareValues); + if (index < 0) { + types.splice(~index, 0, type); + return true; + } + return false; + } + + function addTypeToUnion(typeSet: Type[], includes: TypeFlags, type: Type) { + const flags = type.flags; + // We ignore 'never' types in unions + if (!(flags & TypeFlags.Never)) { + includes |= flags & TypeFlags.IncludesMask; + if (flags & TypeFlags.Instantiable) includes |= TypeFlags.IncludesInstantiable; + if (flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) includes |= TypeFlags.IncludesConstrainedTypeVariable; + if (type === wildcardType) includes |= TypeFlags.IncludesWildcard; + if (isErrorType(type)) includes |= TypeFlags.IncludesError; + if (!strictNullChecks && flags & TypeFlags.Nullable) { + if (!(getObjectFlags(type) & ObjectFlags.ContainsWideningType)) includes |= TypeFlags.IncludesNonWideningType; + } + else { + const len = typeSet.length; + const index = len && type.id > typeSet[len - 1].id ? ~len : binarySearch(typeSet, type, getTypeId, compareValues); + if (index < 0) { + typeSet.splice(~index, 0, type); + } + } + } + return includes; + } + + // Add the given types to the given type set. Order is preserved, duplicates are removed, + // and nested types of the given kind are flattened into the set. + function addTypesToUnion(typeSet: Type[], includes: TypeFlags, types: readonly Type[]): TypeFlags { + let lastType: Type | undefined; + for (const type of types) { + // We skip the type if it is the same as the last type we processed. This simple test particularly + // saves a lot of work for large lists of the same union type, such as when resolving `Record[A]`, + // where A and B are large union types. + if (type !== lastType) { + includes = type.flags & TypeFlags.Union ? + addTypesToUnion(typeSet, includes | (isNamedUnionType(type) ? TypeFlags.Union : 0), (type as UnionType).types) : + addTypeToUnion(typeSet, includes, type); + lastType = type; + } + } + return includes; + } + + function removeSubtypes(types: Type[], hasObjectTypes: boolean): Type[] | undefined { + // [] and [T] immediately reduce to [] and [T] respectively + if (types.length < 2) { + return types; + } + + const id = getTypeListId(types); + const match = subtypeReductionCache.get(id); + if (match) { + return match; + } + + // We assume that redundant primitive types have already been removed from the types array and that there + // are no any and unknown types in the array. Thus, the only possible supertypes for primitive types are empty + // object types, and if none of those are present we can exclude primitive types from the subtype check. + const hasEmptyObject = hasObjectTypes && some(types, t => !!(t.flags & TypeFlags.Object) && !isGenericMappedType(t) && isEmptyResolvedType(resolveStructuredTypeMembers(t as ObjectType))); + const len = types.length; + let i = len; + let count = 0; + while (i > 0) { + i--; + const source = types[i]; + if (hasEmptyObject || source.flags & TypeFlags.StructuredOrInstantiable) { + // A type parameter with a union constraint may be a subtype of some union, but not a subtype of the + // individual constituents of that union. For example, `T extends A | B` is a subtype of `A | B`, but not + // a subtype of just `A` or just `B`. When we encounter such a type parameter, we therefore check if the + // type parameter is a subtype of a union of all the other types. + if (source.flags & TypeFlags.TypeParameter && getBaseConstraintOrType(source).flags & TypeFlags.Union) { + if (isTypeRelatedTo(source, getUnionType(map(types, t => t === source ? neverType : t)), strictSubtypeRelation)) { + orderedRemoveItemAt(types, i); + } + continue; + } + // Find the first property with a unit type, if any. When constituents have a property by the same name + // but of a different unit type, we can quickly disqualify them from subtype checks. This helps subtype + // reduction of large discriminated union types. + const keyProperty = source.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive) ? + find(getPropertiesOfType(source), p => isUnitType(getTypeOfSymbol(p))) : + undefined; + const keyPropertyType = keyProperty && getRegularTypeOfLiteralType(getTypeOfSymbol(keyProperty)); + for (const target of types) { + if (source !== target) { + if (count === 100000) { + // After 100000 subtype checks we estimate the remaining amount of work by assuming the + // same ratio of checks per element. If the estimated number of remaining type checks is + // greater than 1M we deem the union type too complex to represent. This for example + // caps union types at 1000 unique object types. + const estimatedCount = (count / (len - i)) * len; + if (estimatedCount > 1000000) { + tracing?.instant(tracing.Phase.CheckTypes, "removeSubtypes_DepthLimit", { typeIds: types.map(t => t.id) }); + error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent); + return undefined; + } + } + count++; + if (keyProperty && target.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive)) { + const t = getTypeOfPropertyOfType(target, keyProperty.escapedName); + if (t && isUnitType(t) && getRegularTypeOfLiteralType(t) !== keyPropertyType) { + continue; + } + } + if ( + isTypeRelatedTo(source, target, strictSubtypeRelation) && ( + !(getObjectFlags(getTargetType(source)) & ObjectFlags.Class) || + !(getObjectFlags(getTargetType(target)) & ObjectFlags.Class) || + isTypeDerivedFrom(source, target) + ) + ) { + orderedRemoveItemAt(types, i); + break; + } + } + } + } + } + subtypeReductionCache.set(id, types); + return types; + } + + function removeRedundantLiteralTypes(types: Type[], includes: TypeFlags, reduceVoidUndefined: boolean) { + let i = types.length; + while (i > 0) { + i--; + const t = types[i]; + const flags = t.flags; + const remove = flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && includes & TypeFlags.String || + flags & TypeFlags.NumberLiteral && includes & TypeFlags.Number || + flags & TypeFlags.BigIntLiteral && includes & TypeFlags.BigInt || + flags & TypeFlags.UniqueESSymbol && includes & TypeFlags.ESSymbol || + reduceVoidUndefined && flags & TypeFlags.Undefined && includes & TypeFlags.Void || + isFreshLiteralType(t) && containsType(types, (t as LiteralType).regularType); + if (remove) { + orderedRemoveItemAt(types, i); + } + } + } + + function removeStringLiteralsMatchedByTemplateLiterals(types: Type[]) { + const templates = filter(types, isPatternLiteralType) as (TemplateLiteralType | StringMappingType)[]; + if (templates.length) { + let i = types.length; + while (i > 0) { + i--; + const t = types[i]; + if (t.flags & TypeFlags.StringLiteral && some(templates, template => isTypeMatchedByTemplateLiteralOrStringMapping(t, template))) { + orderedRemoveItemAt(types, i); + } + } + } + } + + function isTypeMatchedByTemplateLiteralOrStringMapping(type: Type, template: TemplateLiteralType | StringMappingType) { + return template.flags & TypeFlags.TemplateLiteral ? + isTypeMatchedByTemplateLiteralType(type, template as TemplateLiteralType) : + isMemberOfStringMapping(type, template); + } + + function removeConstrainedTypeVariables(types: Type[]) { + const typeVariables: TypeVariable[] = []; + // First collect a list of the type variables occurring in constraining intersections. + for (const type of types) { + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) { + const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1; + pushIfUnique(typeVariables, (type as IntersectionType).types[index]); + } + } + // For each type variable, check if the constraining intersections for that type variable fully + // cover the constraint of the type variable; if so, remove the constraining intersections and + // substitute the type variable. + for (const typeVariable of typeVariables) { + const primitives: Type[] = []; + // First collect the primitive types from the constraining intersections. + for (const type of types) { + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) { + const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1; + if ((type as IntersectionType).types[index] === typeVariable) { + insertType(primitives, (type as IntersectionType).types[1 - index]); + } + } + } + // If every constituent in the type variable's constraint is covered by an intersection of the type + // variable and that constituent, remove those intersections and substitute the type variable. + const constraint = getBaseConstraintOfType(typeVariable)!; + if (everyType(constraint, t => containsType(primitives, t))) { + let i = types.length; + while (i > 0) { + i--; + const type = types[i]; + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) { + const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1; + if ((type as IntersectionType).types[index] === typeVariable && containsType(primitives, (type as IntersectionType).types[1 - index])) { + orderedRemoveItemAt(types, i); + } + } + } + insertType(types, typeVariable); + } + } + } + + function isNamedUnionType(type: Type) { + return !!(type.flags & TypeFlags.Union && (type.aliasSymbol || (type as UnionType).origin)); + } + + function addNamedUnions(namedUnions: Type[], types: readonly Type[]) { + for (const t of types) { + if (t.flags & TypeFlags.Union) { + const origin = (t as UnionType).origin; + if (t.aliasSymbol || origin && !(origin.flags & TypeFlags.Union)) { + pushIfUnique(namedUnions, t); + } + else if (origin && origin.flags & TypeFlags.Union) { + addNamedUnions(namedUnions, (origin as UnionType).types); + } + } + } + } + + function createOriginUnionOrIntersectionType(flags: TypeFlags, types: Type[]) { + const result = createOriginType(flags) as UnionOrIntersectionType; + result.types = types; + return result; + } + + // We sort and deduplicate the constituent types based on object identity. If the subtypeReduction + // flag is specified we also reduce the constituent type set to only include types that aren't subtypes + // of other types. Subtype reduction is expensive for large union types and is possible only when union + // types are known not to circularly reference themselves (as is the case with union types created by + // expression constructs such as array literals and the || and ?: operators). Named types can + // circularly reference themselves and therefore cannot be subtype reduced during their declaration. + // For example, "type Item = string | (() => Item" is a named type that circularly references itself. + function getUnionType(types: readonly Type[], unionReduction: UnionReduction = UnionReduction.Literal, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[], origin?: Type): Type { + if (types.length === 0) { + return neverType; + } + if (types.length === 1) { + return types[0]; + } + // We optimize for the common case of unioning a union type with some other type (such as `undefined`). + if (types.length === 2 && !origin && (types[0].flags & TypeFlags.Union || types[1].flags & TypeFlags.Union)) { + const infix = unionReduction === UnionReduction.None ? "N" : unionReduction === UnionReduction.Subtype ? "S" : "L"; + const index = types[0].id < types[1].id ? 0 : 1; + const id = types[index].id + infix + types[1 - index].id + getAliasId(aliasSymbol, aliasTypeArguments); + let type = unionOfUnionTypes.get(id); + if (!type) { + type = getUnionTypeWorker(types, unionReduction, aliasSymbol, aliasTypeArguments, /*origin*/ undefined); + unionOfUnionTypes.set(id, type); + } + return type; + } + return getUnionTypeWorker(types, unionReduction, aliasSymbol, aliasTypeArguments, origin); + } + + function getUnionTypeWorker(types: readonly Type[], unionReduction: UnionReduction, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined, origin: Type | undefined): Type { + let typeSet: Type[] | undefined = []; + const includes = addTypesToUnion(typeSet, 0 as TypeFlags, types); + if (unionReduction !== UnionReduction.None) { + if (includes & TypeFlags.AnyOrUnknown) { + return includes & TypeFlags.Any ? + includes & TypeFlags.IncludesWildcard ? wildcardType : + includes & TypeFlags.IncludesError ? errorType : anyType : + unknownType; + } + if (includes & TypeFlags.Undefined) { + // If type set contains both undefinedType and missingType, remove missingType + if (typeSet.length >= 2 && typeSet[0] === undefinedType && typeSet[1] === missingType) { + orderedRemoveItemAt(typeSet, 1); + } + } + if (includes & (TypeFlags.Enum | TypeFlags.Literal | TypeFlags.UniqueESSymbol | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || includes & TypeFlags.Void && includes & TypeFlags.Undefined) { + removeRedundantLiteralTypes(typeSet, includes, !!(unionReduction & UnionReduction.Subtype)); + } + if (includes & TypeFlags.StringLiteral && includes & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping)) { + removeStringLiteralsMatchedByTemplateLiterals(typeSet); + } + if (includes & TypeFlags.IncludesConstrainedTypeVariable) { + removeConstrainedTypeVariables(typeSet); + } + if (unionReduction === UnionReduction.Subtype) { + typeSet = removeSubtypes(typeSet, !!(includes & TypeFlags.Object)); + if (!typeSet) { + return errorType; + } + } + if (typeSet.length === 0) { + return includes & TypeFlags.Null ? includes & TypeFlags.IncludesNonWideningType ? nullType : nullWideningType : + includes & TypeFlags.Undefined ? includes & TypeFlags.IncludesNonWideningType ? undefinedType : undefinedWideningType : + neverType; + } + } + if (!origin && includes & TypeFlags.Union) { + const namedUnions: Type[] = []; + addNamedUnions(namedUnions, types); + const reducedTypes: Type[] = []; + for (const t of typeSet) { + if (!some(namedUnions, union => containsType((union as UnionType).types, t))) { + reducedTypes.push(t); + } + } + if (!aliasSymbol && namedUnions.length === 1 && reducedTypes.length === 0) { + return namedUnions[0]; + } + // We create a denormalized origin type only when the union was created from one or more named unions + // (unions with alias symbols or origins) and when there is no overlap between those named unions. + const namedTypesCount = reduceLeft(namedUnions, (sum, union) => sum + (union as UnionType).types.length, 0); + if (namedTypesCount + reducedTypes.length === typeSet.length) { + for (const t of namedUnions) { + insertType(reducedTypes, t); + } + origin = createOriginUnionOrIntersectionType(TypeFlags.Union, reducedTypes); + } + } + const objectFlags = (includes & TypeFlags.NotPrimitiveUnion ? 0 : ObjectFlags.PrimitiveUnion) | + (includes & TypeFlags.Intersection ? ObjectFlags.ContainsIntersections : 0); + return getUnionTypeFromSortedList(typeSet, objectFlags, aliasSymbol, aliasTypeArguments, origin); + } + + function getUnionOrIntersectionTypePredicate(signatures: readonly Signature[], kind: TypeFlags | undefined): TypePredicate | undefined { + let last: TypePredicate | undefined; + const types: Type[] = []; + for (const sig of signatures) { + const pred = getTypePredicateOfSignature(sig); + if (pred) { + // Constituent type predicates must all have matching kinds. We don't create composite type predicates for assertions. + if (pred.kind !== TypePredicateKind.This && pred.kind !== TypePredicateKind.Identifier || last && !typePredicateKindsMatch(last, pred)) { + return undefined; + } + last = pred; + types.push(pred.type); + } + else { + // In composite union signatures we permit and ignore signatures with a return type `false`. + const returnType = kind !== TypeFlags.Intersection ? getReturnTypeOfSignature(sig) : undefined; + if (returnType !== falseType && returnType !== regularFalseType) { + return undefined; + } + } + } + if (!last) { + return undefined; + } + const compositeType = getUnionOrIntersectionType(types, kind); + return createTypePredicate(last.kind, last.parameterName, last.parameterIndex, compositeType); + } + + function typePredicateKindsMatch(a: TypePredicate, b: TypePredicate): boolean { + return a.kind === b.kind && a.parameterIndex === b.parameterIndex; + } + + // This function assumes the constituent type list is sorted and deduplicated. + function getUnionTypeFromSortedList(types: Type[], precomputedObjectFlags: ObjectFlags, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[], origin?: Type): Type { + if (types.length === 0) { + return neverType; + } + if (types.length === 1) { + return types[0]; + } + const typeKey = !origin ? getTypeListId(types) : + origin.flags & TypeFlags.Union ? `|${getTypeListId((origin as UnionType).types)}` : + origin.flags & TypeFlags.Intersection ? `&${getTypeListId((origin as IntersectionType).types)}` : + `#${(origin as IndexType).type.id}|${getTypeListId(types)}`; // origin type id alone is insufficient, as `keyof x` may resolve to multiple WIP values while `x` is still resolving + const id = typeKey + getAliasId(aliasSymbol, aliasTypeArguments); + let type = unionTypes.get(id); + if (!type) { + type = createType(TypeFlags.Union) as UnionType; + type.objectFlags = precomputedObjectFlags | getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable); + type.types = types; + type.origin = origin; + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = aliasTypeArguments; + if (types.length === 2 && types[0].flags & TypeFlags.BooleanLiteral && types[1].flags & TypeFlags.BooleanLiteral) { + type.flags |= TypeFlags.Boolean; + (type as UnionType & IntrinsicType).intrinsicName = "boolean"; + } + unionTypes.set(id, type); + } + return type; + } + + function getTypeFromUnionTypeNode(node: UnionTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const aliasSymbol = getAliasSymbolForTypeNode(node); + links.resolvedType = getUnionType(map(node.types, getTypeFromTypeNode), UnionReduction.Literal, aliasSymbol, getTypeArgumentsForAliasSymbol(aliasSymbol)); + } + return links.resolvedType; + } + + function addTypeToIntersection(typeSet: Map, includes: TypeFlags, type: Type) { + const flags = type.flags; + if (flags & TypeFlags.Intersection) { + return addTypesToIntersection(typeSet, includes, (type as IntersectionType).types); + } + if (isEmptyAnonymousObjectType(type)) { + if (!(includes & TypeFlags.IncludesEmptyObject)) { + includes |= TypeFlags.IncludesEmptyObject; + typeSet.set(type.id.toString(), type); + } + } + else { + if (flags & TypeFlags.AnyOrUnknown) { + if (type === wildcardType) includes |= TypeFlags.IncludesWildcard; + if (isErrorType(type)) includes |= TypeFlags.IncludesError; + } + else if (strictNullChecks || !(flags & TypeFlags.Nullable)) { + if (type === missingType) { + includes |= TypeFlags.IncludesMissingType; + type = undefinedType; + } + if (!typeSet.has(type.id.toString())) { + if (type.flags & TypeFlags.Unit && includes & TypeFlags.Unit) { + // We have seen two distinct unit types which means we should reduce to an + // empty intersection. Adding TypeFlags.NonPrimitive causes that to happen. + includes |= TypeFlags.NonPrimitive; + } + typeSet.set(type.id.toString(), type); + } + } + includes |= flags & TypeFlags.IncludesMask; + } + return includes; + } + + // Add the given types to the given type set. Order is preserved, freshness is removed from literal + // types, duplicates are removed, and nested types of the given kind are flattened into the set. + function addTypesToIntersection(typeSet: Map, includes: TypeFlags, types: readonly Type[]) { + for (const type of types) { + includes = addTypeToIntersection(typeSet, includes, getRegularTypeOfLiteralType(type)); + } + return includes; + } + + function removeRedundantSupertypes(types: Type[], includes: TypeFlags) { + let i = types.length; + while (i > 0) { + i--; + const t = types[i]; + const remove = t.flags & TypeFlags.String && includes & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || + t.flags & TypeFlags.Number && includes & TypeFlags.NumberLiteral || + t.flags & TypeFlags.BigInt && includes & TypeFlags.BigIntLiteral || + t.flags & TypeFlags.ESSymbol && includes & TypeFlags.UniqueESSymbol || + t.flags & TypeFlags.Void && includes & TypeFlags.Undefined || + isEmptyAnonymousObjectType(t) && includes & TypeFlags.DefinitelyNonNullable; + if (remove) { + orderedRemoveItemAt(types, i); + } + } + } + + // Check that the given type has a match in every union. A given type is matched by + // an identical type, and a literal type is additionally matched by its corresponding + // primitive type. + function eachUnionContains(unionTypes: UnionType[], type: Type) { + for (const u of unionTypes) { + if (!containsType(u.types, type)) { + const primitive = type.flags & TypeFlags.StringLiteral ? stringType : + type.flags & (TypeFlags.Enum | TypeFlags.NumberLiteral) ? numberType : + type.flags & TypeFlags.BigIntLiteral ? bigintType : + type.flags & TypeFlags.UniqueESSymbol ? esSymbolType : + undefined; + if (!primitive || !containsType(u.types, primitive)) { + return false; + } + } + } + return true; + } + + /** + * Returns true if the intersection of the template literals and string literals is the empty set, + * for example `get${string}` & "setX", and should reduce to never. + */ + function extractRedundantTemplateLiterals(types: Type[]): boolean { + let i = types.length; + const literals = filter(types, t => !!(t.flags & TypeFlags.StringLiteral)); + while (i > 0) { + i--; + const t = types[i]; + if (!(t.flags & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping))) continue; + for (const t2 of literals) { + if (isTypeSubtypeOf(t2, t)) { + // For example, `get${T}` & "getX" is just "getX", and Lowercase & "foo" is just "foo" + orderedRemoveItemAt(types, i); + break; + } + else if (isPatternLiteralType(t)) { + return true; + } + } + } + return false; + } + + function removeFromEach(types: Type[], flag: TypeFlags) { + for (let i = 0; i < types.length; i++) { + types[i] = filterType(types[i], t => !(t.flags & flag)); + } + } + + // If the given list of types contains more than one union of primitive types, replace the + // first with a union containing an intersection of those primitive types, then remove the + // other unions and return true. Otherwise, do nothing and return false. + function intersectUnionsOfPrimitiveTypes(types: Type[]) { + let unionTypes: UnionType[] | undefined; + const index = findIndex(types, t => !!(getObjectFlags(t) & ObjectFlags.PrimitiveUnion)); + if (index < 0) { + return false; + } + let i = index + 1; + // Remove all but the first union of primitive types and collect them in + // the unionTypes array. + while (i < types.length) { + const t = types[i]; + if (getObjectFlags(t) & ObjectFlags.PrimitiveUnion) { + (unionTypes || (unionTypes = [types[index] as UnionType])).push(t as UnionType); + orderedRemoveItemAt(types, i); + } + else { + i++; + } + } + // Return false if there was only one union of primitive types + if (!unionTypes) { + return false; + } + // We have more than one union of primitive types, now intersect them. For each + // type in each union we check if the type is matched in every union and if so + // we include it in the result. + const checked: Type[] = []; + const result: Type[] = []; + for (const u of unionTypes) { + for (const t of u.types) { + if (insertType(checked, t)) { + if (eachUnionContains(unionTypes, t)) { + insertType(result, t); + } + } + } + } + // Finally replace the first union with the result + types[index] = getUnionTypeFromSortedList(result, ObjectFlags.PrimitiveUnion); + return true; + } + + function createIntersectionType(types: Type[], objectFlags: ObjectFlags, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]) { + const result = createType(TypeFlags.Intersection) as IntersectionType; + result.objectFlags = objectFlags | getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable); + result.types = types; + result.aliasSymbol = aliasSymbol; + result.aliasTypeArguments = aliasTypeArguments; + return result; + } + + // We normalize combinations of intersection and union types based on the distributive property of the '&' + // operator. Specifically, because X & (A | B) is equivalent to X & A | X & B, we can transform intersection + // types with union type constituents into equivalent union types with intersection type constituents and + // effectively ensure that union types are always at the top level in type representations. + // + // We do not perform structural deduplication on intersection types. Intersection types are created only by the & + // type operator and we can't reduce those because we want to support recursive intersection types. For example, + // a type alias of the form "type List = T & { next: List }" cannot be reduced during its declaration. + // Also, unlike union types, the order of the constituent types is preserved in order that overload resolution + // for intersections of types with signatures can be deterministic. + function getIntersectionType(types: readonly Type[], flags = IntersectionFlags.None, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + const typeMembershipMap = new Map(); + const includes = addTypesToIntersection(typeMembershipMap, 0 as TypeFlags, types); + const typeSet: Type[] = arrayFrom(typeMembershipMap.values()); + let objectFlags = ObjectFlags.None; + // An intersection type is considered empty if it contains + // the type never, or + // more than one unit type or, + // an object type and a nullable type (null or undefined), or + // a string-like type and a type known to be non-string-like, or + // a number-like type and a type known to be non-number-like, or + // a symbol-like type and a type known to be non-symbol-like, or + // a void-like type and a type known to be non-void-like, or + // a non-primitive type and a type known to be primitive. + if (includes & TypeFlags.Never) { + return contains(typeSet, silentNeverType) ? silentNeverType : neverType; + } + if ( + strictNullChecks && includes & TypeFlags.Nullable && includes & (TypeFlags.Object | TypeFlags.NonPrimitive | TypeFlags.IncludesEmptyObject) || + includes & TypeFlags.NonPrimitive && includes & (TypeFlags.DisjointDomains & ~TypeFlags.NonPrimitive) || + includes & TypeFlags.StringLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.StringLike) || + includes & TypeFlags.NumberLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.NumberLike) || + includes & TypeFlags.BigIntLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.BigIntLike) || + includes & TypeFlags.ESSymbolLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.ESSymbolLike) || + includes & TypeFlags.VoidLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.VoidLike) + ) { + return neverType; + } + if (includes & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && includes & TypeFlags.StringLiteral && extractRedundantTemplateLiterals(typeSet)) { + return neverType; + } + if (includes & TypeFlags.Any) { + return includes & TypeFlags.IncludesWildcard ? wildcardType : includes & TypeFlags.IncludesError ? errorType : anyType; + } + if (!strictNullChecks && includes & TypeFlags.Nullable) { + return includes & TypeFlags.IncludesEmptyObject ? neverType : includes & TypeFlags.Undefined ? undefinedType : nullType; + } + if ( + includes & TypeFlags.String && includes & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || + includes & TypeFlags.Number && includes & TypeFlags.NumberLiteral || + includes & TypeFlags.BigInt && includes & TypeFlags.BigIntLiteral || + includes & TypeFlags.ESSymbol && includes & TypeFlags.UniqueESSymbol || + includes & TypeFlags.Void && includes & TypeFlags.Undefined || + includes & TypeFlags.IncludesEmptyObject && includes & TypeFlags.DefinitelyNonNullable + ) { + if (!(flags & IntersectionFlags.NoSupertypeReduction)) removeRedundantSupertypes(typeSet, includes); + } + if (includes & TypeFlags.IncludesMissingType) { + typeSet[typeSet.indexOf(undefinedType)] = missingType; + } + if (typeSet.length === 0) { + return unknownType; + } + if (typeSet.length === 1) { + return typeSet[0]; + } + if (typeSet.length === 2 && !(flags & IntersectionFlags.NoConstraintReduction)) { + const typeVarIndex = typeSet[0].flags & TypeFlags.TypeVariable ? 0 : 1; + const typeVariable = typeSet[typeVarIndex]; + const primitiveType = typeSet[1 - typeVarIndex]; + if ( + typeVariable.flags & TypeFlags.TypeVariable && + (primitiveType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive) && !isGenericStringLikeType(primitiveType) || includes & TypeFlags.IncludesEmptyObject) + ) { + // We have an intersection T & P or P & T, where T is a type variable and P is a primitive type, the object type, or {}. + const constraint = getBaseConstraintOfType(typeVariable); + // Check that T's constraint is similarly composed of primitive types, the object type, or {}. + if (constraint && everyType(constraint, t => !!(t.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive)) || isEmptyAnonymousObjectType(t))) { + // If T's constraint is a subtype of P, simply return T. For example, given `T extends "a" | "b"`, + // the intersection `T & string` reduces to just T. + if (isTypeStrictSubtypeOf(constraint, primitiveType)) { + return typeVariable; + } + if (!(constraint.flags & TypeFlags.Union && someType(constraint, c => isTypeStrictSubtypeOf(c, primitiveType)))) { + // No constituent of T's constraint is a subtype of P. If P is also not a subtype of T's constraint, + // then the constraint and P are unrelated, and the intersection reduces to never. For example, given + // `T extends "a" | "b"`, the intersection `T & number` reduces to never. + if (!isTypeStrictSubtypeOf(primitiveType, constraint)) { + return neverType; + } + } + // Some constituent of T's constraint is a subtype of P, or P is a subtype of T's constraint. Thus, + // the intersection further constrains the type variable. For example, given `T extends string | number`, + // the intersection `T & "a"` is marked as a constrained type variable. Likewise, given `T extends "a" | 1`, + // the intersection `T & number` is marked as a constrained type variable. + objectFlags = ObjectFlags.IsConstrainedTypeVariable; + } + } + } + const id = getTypeListId(typeSet) + (flags & IntersectionFlags.NoConstraintReduction ? "*" : getAliasId(aliasSymbol, aliasTypeArguments)); + let result = intersectionTypes.get(id); + if (!result) { + if (includes & TypeFlags.Union) { + if (intersectUnionsOfPrimitiveTypes(typeSet)) { + // When the intersection creates a reduced set (which might mean that *all* union types have + // disappeared), we restart the operation to get a new set of combined flags. Once we have + // reduced we'll never reduce again, so this occurs at most once. + result = getIntersectionType(typeSet, flags, aliasSymbol, aliasTypeArguments); + } + else if (every(typeSet, t => !!(t.flags & TypeFlags.Union && (t as UnionType).types[0].flags & TypeFlags.Undefined))) { + const containedUndefinedType = some(typeSet, containsMissingType) ? missingType : undefinedType; + removeFromEach(typeSet, TypeFlags.Undefined); + result = getUnionType([getIntersectionType(typeSet, flags), containedUndefinedType], UnionReduction.Literal, aliasSymbol, aliasTypeArguments); + } + else if (every(typeSet, t => !!(t.flags & TypeFlags.Union && ((t as UnionType).types[0].flags & TypeFlags.Null || (t as UnionType).types[1].flags & TypeFlags.Null)))) { + removeFromEach(typeSet, TypeFlags.Null); + result = getUnionType([getIntersectionType(typeSet, flags), nullType], UnionReduction.Literal, aliasSymbol, aliasTypeArguments); + } + else if (typeSet.length >= 4) { + // When we have four or more constituents, some of which are unions, we employ a "divide and conquer" strategy + // where A & B & C & D is processed as (A & B) & (C & D). Since intersections of unions often produce far smaller + // unions of intersections than the full cartesian product (due to some intersections becoming `never`), this can + // dramatically reduce the overall work. + const middle = Math.floor(typeSet.length / 2); + result = getIntersectionType([getIntersectionType(typeSet.slice(0, middle), flags), getIntersectionType(typeSet.slice(middle), flags)], flags, aliasSymbol, aliasTypeArguments); + } + else { + // We are attempting to construct a type of the form X & (A | B) & (C | D). Transform this into a type of + // the form X & A & C | X & A & D | X & B & C | X & B & D. If the estimated size of the resulting union type + // exceeds 100000 constituents, report an error. + if (!checkCrossProductUnion(typeSet)) { + return errorType; + } + const constituents = getCrossProductIntersections(typeSet, flags); + // We attach a denormalized origin type when at least one constituent of the cross-product union is an + // intersection (i.e. when the intersection didn't just reduce one or more unions to smaller unions) and + // the denormalized origin has fewer constituents than the union itself. + const origin = some(constituents, t => !!(t.flags & TypeFlags.Intersection)) && getConstituentCountOfTypes(constituents) > getConstituentCountOfTypes(typeSet) ? createOriginUnionOrIntersectionType(TypeFlags.Intersection, typeSet) : undefined; + result = getUnionType(constituents, UnionReduction.Literal, aliasSymbol, aliasTypeArguments, origin); + } + } + else { + result = createIntersectionType(typeSet, objectFlags, aliasSymbol, aliasTypeArguments); + } + intersectionTypes.set(id, result); + } + return result; + } + + function getCrossProductUnionSize(types: readonly Type[]) { + return reduceLeft(types, (n, t) => t.flags & TypeFlags.Union ? n * (t as UnionType).types.length : t.flags & TypeFlags.Never ? 0 : n, 1); + } + + function checkCrossProductUnion(types: readonly Type[]) { + const size = getCrossProductUnionSize(types); + if (size >= 100000) { + tracing?.instant(tracing.Phase.CheckTypes, "checkCrossProductUnion_DepthLimit", { typeIds: types.map(t => t.id), size }); + error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent); + return false; + } + return true; + } + + function getCrossProductIntersections(types: readonly Type[], flags: IntersectionFlags) { + const count = getCrossProductUnionSize(types); + const intersections: Type[] = []; + for (let i = 0; i < count; i++) { + const constituents = types.slice(); + let n = i; + for (let j = types.length - 1; j >= 0; j--) { + if (types[j].flags & TypeFlags.Union) { + const sourceTypes = (types[j] as UnionType).types; + const length = sourceTypes.length; + constituents[j] = sourceTypes[n % length]; + n = Math.floor(n / length); + } + } + const t = getIntersectionType(constituents, flags); + if (!(t.flags & TypeFlags.Never)) intersections.push(t); + } + return intersections; + } + + function getConstituentCount(type: Type): number { + return !(type.flags & TypeFlags.UnionOrIntersection) || type.aliasSymbol ? 1 : + type.flags & TypeFlags.Union && (type as UnionType).origin ? getConstituentCount((type as UnionType).origin!) : + getConstituentCountOfTypes((type as UnionOrIntersectionType).types); + } + + function getConstituentCountOfTypes(types: Type[]): number { + return reduceLeft(types, (n, t) => n + getConstituentCount(t), 0); + } + + function getTypeFromIntersectionTypeNode(node: IntersectionTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const aliasSymbol = getAliasSymbolForTypeNode(node); + const types = map(node.types, getTypeFromTypeNode); + // We perform no supertype reduction for X & {} or {} & X, where X is one of string, number, bigint, + // or a pattern literal template type. This enables union types like "a" | "b" | string & {} or + // "aa" | "ab" | `a${string}` which preserve the literal types for purposes of statement completion. + const emptyIndex = types.length === 2 ? types.indexOf(emptyTypeLiteralType) : -1; + const t = emptyIndex >= 0 ? types[1 - emptyIndex] : unknownType; + const noSupertypeReduction = !!(t.flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt) || t.flags & TypeFlags.TemplateLiteral && isPatternLiteralType(t)); + links.resolvedType = getIntersectionType(types, noSupertypeReduction ? IntersectionFlags.NoSupertypeReduction : 0, aliasSymbol, getTypeArgumentsForAliasSymbol(aliasSymbol)); + } + return links.resolvedType; + } + + function createIndexType(type: InstantiableType | UnionOrIntersectionType, indexFlags: IndexFlags) { + const result = createType(TypeFlags.Index) as IndexType; + result.type = type; + result.indexFlags = indexFlags; + return result; + } + + function createOriginIndexType(type: InstantiableType | UnionOrIntersectionType) { + const result = createOriginType(TypeFlags.Index) as IndexType; + result.type = type; + return result; + } + + function getIndexTypeForGenericType(type: InstantiableType | UnionOrIntersectionType, indexFlags: IndexFlags) { + return indexFlags & IndexFlags.StringsOnly ? + type.resolvedStringIndexType || (type.resolvedStringIndexType = createIndexType(type, IndexFlags.StringsOnly)) : + type.resolvedIndexType || (type.resolvedIndexType = createIndexType(type, IndexFlags.None)); + } + + /** + * This roughly mirrors `resolveMappedTypeMembers` in the nongeneric case, except only reports a union of the keys calculated, + * rather than manufacturing the properties. We can't just fetch the `constraintType` since that would ignore mappings + * and mapping the `constraintType` directly ignores how mapped types map _properties_ and not keys (thus ignoring subtype + * reduction in the constraintType) when possible. + * @param noIndexSignatures Indicates if _string_ index signatures should be elided. (other index signatures are always reported) + */ + function getIndexTypeForMappedType(type: MappedType, indexFlags: IndexFlags) { + const typeParameter = getTypeParameterFromMappedType(type); + const constraintType = getConstraintTypeFromMappedType(type); + const nameType = getNameTypeFromMappedType(type.target as MappedType || type); + if (!nameType && !(indexFlags & IndexFlags.NoIndexSignatures)) { + // no mapping and no filtering required, just quickly bail to returning the constraint in the common case + return constraintType; + } + const keyTypes: Type[] = []; + // Calling getApparentType on the `T` of a `keyof T` in the constraint type of a generic mapped type can + // trigger a circularity. For example, `T extends { [P in keyof T & string as Captitalize

]: any }` is + // a circular definition. For this reason, we only eagerly manifest the keys if the constraint is non-generic. + if (isGenericIndexType(constraintType)) { + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // We have a generic index and a homomorphic mapping (but a distributive key remapping) - we need to defer + // the whole `keyof whatever` for later since it's not safe to resolve the shape of modifier type. + return getIndexTypeForGenericType(type, indexFlags); + } + // Include the generic component in the resulting type. + forEachType(constraintType, addMemberForKeyType); + } + else if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + const modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T' + forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(modifiersType, TypeFlags.StringOrNumberLiteralOrUnique, !!(indexFlags & IndexFlags.StringsOnly), addMemberForKeyType); + } + else { + forEachType(getLowerBoundOfKeyType(constraintType), addMemberForKeyType); + } + // We had to pick apart the constraintType to potentially map/filter it - compare the final resulting list with the + // original constraintType, so we can return the union that preserves aliases/origin data if possible. + const result = indexFlags & IndexFlags.NoIndexSignatures ? filterType(getUnionType(keyTypes), t => !(t.flags & (TypeFlags.Any | TypeFlags.String))) : getUnionType(keyTypes); + if (result.flags & TypeFlags.Union && constraintType.flags & TypeFlags.Union && getTypeListId((result as UnionType).types) === getTypeListId((constraintType as UnionType).types)) { + return constraintType; + } + return result; + + function addMemberForKeyType(keyType: Type) { + const propNameType = nameType ? instantiateType(nameType, appendTypeMapping(type.mapper, typeParameter, keyType)) : keyType; + // `keyof` currently always returns `string | number` for concrete `string` index signatures - the below ternary keeps that behavior for mapped types + // See `getLiteralTypeFromProperties` where there's a similar ternary to cause the same behavior. + keyTypes.push(propNameType === stringType ? stringOrNumberType : propNameType); + } + } + + // Ordinarily we reduce a keyof M, where M is a mapped type { [P in K as N

) + const { expression } = node as JsxExpression; + return !!expression && isContextSensitive(expression); + } + } + + return false; + } + + function isContextSensitiveFunctionLikeDeclaration(node: FunctionLikeDeclaration): boolean { + return hasContextSensitiveParameters(node) || hasContextSensitiveReturnExpression(node); + } + + function hasContextSensitiveReturnExpression(node: FunctionLikeDeclaration) { + if (node.typeParameters || getEffectiveReturnTypeNode(node) || !node.body) { + return false; + } + if (node.body.kind !== SyntaxKind.Block) { + return isContextSensitive(node.body); + } + return !!forEachReturnStatement(node.body as Block, statement => !!statement.expression && isContextSensitive(statement.expression)); + } + + function isContextSensitiveFunctionOrObjectLiteralMethod(func: Node): func is FunctionExpression | ArrowFunction | MethodDeclaration { + return (isFunctionExpressionOrArrowFunction(func) || isObjectLiteralMethod(func)) && + isContextSensitiveFunctionLikeDeclaration(func); + } + + function getTypeWithoutSignatures(type: Type): Type { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + if (resolved.constructSignatures.length || resolved.callSignatures.length) { + const result = createObjectType(ObjectFlags.Anonymous, type.symbol); + result.members = resolved.members; + result.properties = resolved.properties; + result.callSignatures = emptyArray; + result.constructSignatures = emptyArray; + result.indexInfos = emptyArray; + return result; + } + } + else if (type.flags & TypeFlags.Intersection) { + return getIntersectionType(map((type as IntersectionType).types, getTypeWithoutSignatures)); + } + return type; + } + + // TYPE CHECKING + + function isTypeIdenticalTo(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, identityRelation); + } + + function compareTypesIdentical(source: Type, target: Type): Ternary { + return isTypeRelatedTo(source, target, identityRelation) ? Ternary.True : Ternary.False; + } + + function compareTypesAssignable(source: Type, target: Type): Ternary { + return isTypeRelatedTo(source, target, assignableRelation) ? Ternary.True : Ternary.False; + } + + function compareTypesSubtypeOf(source: Type, target: Type): Ternary { + return isTypeRelatedTo(source, target, subtypeRelation) ? Ternary.True : Ternary.False; + } + + function isTypeSubtypeOf(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, subtypeRelation); + } + + function isTypeStrictSubtypeOf(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, strictSubtypeRelation); + } + + function isTypeAssignableTo(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, assignableRelation); + } + + // An object type S is considered to be derived from an object type T if + // S is a union type and every constituent of S is derived from T, + // T is a union type and S is derived from at least one constituent of T, or + // S is an intersection type and some constituent of S is derived from T, or + // S is a type variable with a base constraint that is derived from T, or + // T is {} and S is an object-like type (ensuring {} is less derived than Object), or + // T is one of the global types Object and Function and S is a subtype of T, or + // T occurs directly or indirectly in an 'extends' clause of S. + // Note that this check ignores type parameters and only considers the + // inheritance hierarchy. + function isTypeDerivedFrom(source: Type, target: Type): boolean { + return source.flags & TypeFlags.Union ? every((source as UnionType).types, t => isTypeDerivedFrom(t, target)) : + target.flags & TypeFlags.Union ? some((target as UnionType).types, t => isTypeDerivedFrom(source, t)) : + source.flags & TypeFlags.Intersection ? some((source as IntersectionType).types, t => isTypeDerivedFrom(t, target)) : + source.flags & TypeFlags.InstantiableNonPrimitive ? isTypeDerivedFrom(getBaseConstraintOfType(source) || unknownType, target) : + isEmptyAnonymousObjectType(target) ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) : + target === globalObjectType ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) && !isEmptyAnonymousObjectType(source) : + target === globalFunctionType ? !!(source.flags & TypeFlags.Object) && isFunctionObjectType(source as ObjectType) : + hasBaseType(source, getTargetType(target)) || (isArrayType(target) && !isReadonlyArrayType(target) && isTypeDerivedFrom(source, globalReadonlyArrayType)); + } + + /** + * This is *not* a bi-directional relationship. + * If one needs to check both directions for comparability, use a second call to this function or 'checkTypeComparableTo'. + * + * A type S is comparable to a type T if some (but not necessarily all) of the possible values of S are also possible values of T. + * It is used to check following cases: + * - the types of the left and right sides of equality/inequality operators (`===`, `!==`, `==`, `!=`). + * - the types of `case` clause expressions and their respective `switch` expressions. + * - the type of an expression in a type assertion with the type being asserted. + */ + function isTypeComparableTo(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, comparableRelation); + } + + function areTypesComparable(type1: Type, type2: Type): boolean { + return isTypeComparableTo(type1, type2) || isTypeComparableTo(type2, type1); + } + + function checkTypeAssignableTo(source: Type, target: Type, errorNode: Node | undefined, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined, errorOutputObject?: { errors?: Diagnostic[]; }): boolean { + return checkTypeRelatedTo(source, target, assignableRelation, errorNode, headMessage, containingMessageChain, errorOutputObject); + } + + /** + * Like `checkTypeAssignableTo`, but if it would issue an error, instead performs structural comparisons of the types using the given expression node to + * attempt to issue more specific errors on, for example, specific object literal properties or tuple members. + */ + function checkTypeAssignableToAndOptionallyElaborate(source: Type, target: Type, errorNode: Node | undefined, expr: Expression | undefined, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined): boolean { + return checkTypeRelatedToAndOptionallyElaborate(source, target, assignableRelation, errorNode, expr, headMessage, containingMessageChain, /*errorOutputContainer*/ undefined); + } + + function checkTypeRelatedToAndOptionallyElaborate( + source: Type, + target: Type, + relation: Map, + errorNode: Node | undefined, + expr: Expression | undefined, + headMessage: DiagnosticMessage | undefined, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + if (isTypeRelatedTo(source, target, relation)) return true; + if (!errorNode || !elaborateError(expr, source, target, relation, headMessage, containingMessageChain, errorOutputContainer)) { + return checkTypeRelatedTo(source, target, relation, errorNode, headMessage, containingMessageChain, errorOutputContainer); + } + return false; + } + + function isOrHasGenericConditional(type: Type): boolean { + return !!(type.flags & TypeFlags.Conditional || (type.flags & TypeFlags.Intersection && some((type as IntersectionType).types, isOrHasGenericConditional))); + } + + function elaborateError( + node: Expression | undefined, + source: Type, + target: Type, + relation: Map, + headMessage: DiagnosticMessage | undefined, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + if (!node || isOrHasGenericConditional(target)) return false; + if ( + !checkTypeRelatedTo(source, target, relation, /*errorNode*/ undefined) + && elaborateDidYouMeanToCallOrConstruct(node, source, target, relation, headMessage, containingMessageChain, errorOutputContainer) + ) { + return true; + } + switch (node.kind) { + case SyntaxKind.AsExpression: + if (!isConstAssertion(node)) { + break; + } + // fallthrough + case SyntaxKind.JsxExpression: + case SyntaxKind.ParenthesizedExpression: + return elaborateError((node as AsExpression | ParenthesizedExpression | JsxExpression).expression, source, target, relation, headMessage, containingMessageChain, errorOutputContainer); + case SyntaxKind.BinaryExpression: + switch ((node as BinaryExpression).operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.CommaToken: + return elaborateError((node as BinaryExpression).right, source, target, relation, headMessage, containingMessageChain, errorOutputContainer); + } + break; + case SyntaxKind.ObjectLiteralExpression: + return elaborateObjectLiteral(node as ObjectLiteralExpression, source, target, relation, containingMessageChain, errorOutputContainer); + case SyntaxKind.ArrayLiteralExpression: + return elaborateArrayLiteral(node as ArrayLiteralExpression, source, target, relation, containingMessageChain, errorOutputContainer); + case SyntaxKind.JsxAttributes: + return elaborateJsxComponents(node as JsxAttributes, source, target, relation, containingMessageChain, errorOutputContainer); + case SyntaxKind.ArrowFunction: + return elaborateArrowFunction(node as ArrowFunction, source, target, relation, containingMessageChain, errorOutputContainer); + } + return false; + } + + function elaborateDidYouMeanToCallOrConstruct( + node: Expression, + source: Type, + target: Type, + relation: Map, + headMessage: DiagnosticMessage | undefined, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + const callSignatures = getSignaturesOfType(source, SignatureKind.Call); + const constructSignatures = getSignaturesOfType(source, SignatureKind.Construct); + for (const signatures of [constructSignatures, callSignatures]) { + if ( + some(signatures, s => { + const returnType = getReturnTypeOfSignature(s); + return !(returnType.flags & (TypeFlags.Any | TypeFlags.Never)) && checkTypeRelatedTo(returnType, target, relation, /*errorNode*/ undefined); + }) + ) { + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + checkTypeAssignableTo(source, target, node, headMessage, containingMessageChain, resultObj); + const diagnostic = resultObj.errors![resultObj.errors!.length - 1]; + addRelatedInfo( + diagnostic, + createDiagnosticForNode( + node, + signatures === constructSignatures ? Diagnostics.Did_you_mean_to_use_new_with_this_expression : Diagnostics.Did_you_mean_to_call_this_expression, + ), + ); + return true; + } + } + return false; + } + + function elaborateArrowFunction( + node: ArrowFunction, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + // Don't elaborate blocks + if (isBlock(node.body)) { + return false; + } + // Or functions with annotated parameter types + if (some(node.parameters, hasType)) { + return false; + } + const sourceSig = getSingleCallSignature(source); + if (!sourceSig) { + return false; + } + const targetSignatures = getSignaturesOfType(target, SignatureKind.Call); + if (!length(targetSignatures)) { + return false; + } + const returnExpression = node.body; + const sourceReturn = getReturnTypeOfSignature(sourceSig); + const targetReturn = getUnionType(map(targetSignatures, getReturnTypeOfSignature)); + if (!checkTypeRelatedTo(sourceReturn, targetReturn, relation, /*errorNode*/ undefined)) { + const elaborated = returnExpression && elaborateError(returnExpression, sourceReturn, targetReturn, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); + if (elaborated) { + return elaborated; + } + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + checkTypeRelatedTo(sourceReturn, targetReturn, relation, returnExpression, /*headMessage*/ undefined, containingMessageChain, resultObj); + if (resultObj.errors) { + if (target.symbol && length(target.symbol.declarations)) { + addRelatedInfo( + resultObj.errors[resultObj.errors.length - 1], + createDiagnosticForNode( + target.symbol.declarations![0], + Diagnostics.The_expected_type_comes_from_the_return_type_of_this_signature, + ), + ); + } + if ( + (getFunctionFlags(node) & FunctionFlags.Async) === 0 + // exclude cases where source itself is promisy - this way we don't make a suggestion when relating + // an IPromise and a Promise that are slightly different + && !getTypeOfPropertyOfType(sourceReturn, "then" as __String) + && checkTypeRelatedTo(createPromiseType(sourceReturn), targetReturn, relation, /*errorNode*/ undefined) + ) { + addRelatedInfo( + resultObj.errors[resultObj.errors.length - 1], + createDiagnosticForNode( + node, + Diagnostics.Did_you_mean_to_mark_this_function_as_async, + ), + ); + } + return true; + } + } + return false; + } + + function getBestMatchIndexedAccessTypeOrUndefined(source: Type, target: Type, nameType: Type) { + const idx = getIndexedAccessTypeOrUndefined(target, nameType); + if (idx) { + return idx; + } + if (target.flags & TypeFlags.Union) { + const best = getBestMatchingType(source, target as UnionType); + if (best) { + return getIndexedAccessTypeOrUndefined(best, nameType); + } + } + } + + function checkExpressionForMutableLocationWithContextualType(next: Expression, sourcePropType: Type) { + pushContextualType(next, sourcePropType, /*isCache*/ false); + const result = checkExpressionForMutableLocation(next, CheckMode.Contextual); + popContextualType(); + return result; + } + + type ElaborationIterator = IterableIterator<{ errorNode: Node; innerExpression: Expression | undefined; nameType: Type; errorMessage?: DiagnosticMessage | undefined; }>; + /** + * For every element returned from the iterator, checks that element to issue an error on a property of that element's type + * If that element would issue an error, we first attempt to dive into that element's inner expression and issue a more specific error by recuring into `elaborateError` + * Otherwise, we issue an error on _every_ element which fail the assignability check + */ + function elaborateElementwise( + iterator: ElaborationIterator, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + // Assignability failure - check each prop individually, and if that fails, fall back on the bad error span + let reportedError = false; + for (const value of iterator) { + const { errorNode: prop, innerExpression: next, nameType, errorMessage } = value; + let targetPropType = getBestMatchIndexedAccessTypeOrUndefined(source, target, nameType); + if (!targetPropType || targetPropType.flags & TypeFlags.IndexedAccess) continue; // Don't elaborate on indexes on generic variables + let sourcePropType = getIndexedAccessTypeOrUndefined(source, nameType); + if (!sourcePropType) continue; + const propName = getPropertyNameFromIndex(nameType, /*accessNode*/ undefined); + if (!checkTypeRelatedTo(sourcePropType, targetPropType, relation, /*errorNode*/ undefined)) { + const elaborated = next && elaborateError(next, sourcePropType, targetPropType, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); + reportedError = true; + if (!elaborated) { + // Issue error on the prop itself, since the prop couldn't elaborate the error + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + // Use the expression type, if available + const specificSource = next ? checkExpressionForMutableLocationWithContextualType(next, sourcePropType) : sourcePropType; + if (exactOptionalPropertyTypes && isExactOptionalPropertyMismatch(specificSource, targetPropType)) { + const diag = createDiagnosticForNode(prop, Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target, typeToString(specificSource), typeToString(targetPropType)); + diagnostics.add(diag); + resultObj.errors = [diag]; + } + else { + const targetIsOptional = !!(propName && (getPropertyOfType(target, propName) || unknownSymbol).flags & SymbolFlags.Optional); + const sourceIsOptional = !!(propName && (getPropertyOfType(source, propName) || unknownSymbol).flags & SymbolFlags.Optional); + targetPropType = removeMissingType(targetPropType, targetIsOptional); + sourcePropType = removeMissingType(sourcePropType, targetIsOptional && sourceIsOptional); + const result = checkTypeRelatedTo(specificSource, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + if (result && specificSource !== sourcePropType) { + // If for whatever reason the expression type doesn't yield an error, make sure we still issue an error on the sourcePropType + checkTypeRelatedTo(sourcePropType, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + } + } + if (resultObj.errors) { + const reportedDiag = resultObj.errors[resultObj.errors.length - 1]; + const propertyName = isTypeUsableAsPropertyName(nameType) ? getPropertyNameFromType(nameType) : undefined; + const targetProp = propertyName !== undefined ? getPropertyOfType(target, propertyName) : undefined; + + let issuedElaboration = false; + if (!targetProp) { + const indexInfo = getApplicableIndexInfo(target, nameType); + if (indexInfo && indexInfo.declaration && !getSourceFileOfNode(indexInfo.declaration).hasNoDefaultLib) { + issuedElaboration = true; + addRelatedInfo(reportedDiag, createDiagnosticForNode(indexInfo.declaration, Diagnostics.The_expected_type_comes_from_this_index_signature)); + } + } + + if (!issuedElaboration && (targetProp && length(targetProp.declarations) || target.symbol && length(target.symbol.declarations))) { + const targetNode = targetProp && length(targetProp.declarations) ? targetProp.declarations![0] : target.symbol.declarations![0]; + if (!getSourceFileOfNode(targetNode).hasNoDefaultLib) { + addRelatedInfo( + reportedDiag, + createDiagnosticForNode( + targetNode, + Diagnostics.The_expected_type_comes_from_property_0_which_is_declared_here_on_type_1, + propertyName && !(nameType.flags & TypeFlags.UniqueESSymbol) ? unescapeLeadingUnderscores(propertyName) : typeToString(nameType), + typeToString(target), + ), + ); + } + } + } + } + } + } + return reportedError; + } + + /** + * Assumes `target` type is assignable to the `Iterable` type, if `Iterable` is defined, + * or that it's an array or tuple-like type, if `Iterable` is not defined. + */ + function elaborateIterableOrArrayLikeTargetElementwise( + iterator: ElaborationIterator, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + const tupleOrArrayLikeTargetParts = filterType(target, isArrayOrTupleLikeType); + const nonTupleOrArrayLikeTargetParts = filterType(target, t => !isArrayOrTupleLikeType(t)); + // If `nonTupleOrArrayLikeTargetParts` is not `never`, then that should mean `Iterable` is defined. + const iterationType = nonTupleOrArrayLikeTargetParts !== neverType + ? getIterationTypeOfIterable(IterationUse.ForOf, IterationTypeKind.Yield, nonTupleOrArrayLikeTargetParts, /*errorNode*/ undefined) + : undefined; + + let reportedError = false; + for (let status = iterator.next(); !status.done; status = iterator.next()) { + const { errorNode: prop, innerExpression: next, nameType, errorMessage } = status.value; + let targetPropType = iterationType; + const targetIndexedPropType = tupleOrArrayLikeTargetParts !== neverType ? getBestMatchIndexedAccessTypeOrUndefined(source, tupleOrArrayLikeTargetParts, nameType) : undefined; + if (targetIndexedPropType && !(targetIndexedPropType.flags & TypeFlags.IndexedAccess)) { // Don't elaborate on indexes on generic variables + targetPropType = iterationType ? getUnionType([iterationType, targetIndexedPropType]) : targetIndexedPropType; + } + if (!targetPropType) continue; + let sourcePropType = getIndexedAccessTypeOrUndefined(source, nameType); + if (!sourcePropType) continue; + const propName = getPropertyNameFromIndex(nameType, /*accessNode*/ undefined); + if (!checkTypeRelatedTo(sourcePropType, targetPropType, relation, /*errorNode*/ undefined)) { + const elaborated = next && elaborateError(next, sourcePropType, targetPropType, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); + reportedError = true; + if (!elaborated) { + // Issue error on the prop itself, since the prop couldn't elaborate the error + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + // Use the expression type, if available + const specificSource = next ? checkExpressionForMutableLocationWithContextualType(next, sourcePropType) : sourcePropType; + if (exactOptionalPropertyTypes && isExactOptionalPropertyMismatch(specificSource, targetPropType)) { + const diag = createDiagnosticForNode(prop, Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target, typeToString(specificSource), typeToString(targetPropType)); + diagnostics.add(diag); + resultObj.errors = [diag]; + } + else { + const targetIsOptional = !!(propName && (getPropertyOfType(tupleOrArrayLikeTargetParts, propName) || unknownSymbol).flags & SymbolFlags.Optional); + const sourceIsOptional = !!(propName && (getPropertyOfType(source, propName) || unknownSymbol).flags & SymbolFlags.Optional); + targetPropType = removeMissingType(targetPropType, targetIsOptional); + sourcePropType = removeMissingType(sourcePropType, targetIsOptional && sourceIsOptional); + const result = checkTypeRelatedTo(specificSource, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + if (result && specificSource !== sourcePropType) { + // If for whatever reason the expression type doesn't yield an error, make sure we still issue an error on the sourcePropType + checkTypeRelatedTo(sourcePropType, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + } + } + } + } + } + return reportedError; + } + + function* generateJsxAttributes(node: JsxAttributes): ElaborationIterator { + if (!length(node.properties)) return; + for (const prop of node.properties) { + if (isJsxSpreadAttribute(prop) || isHyphenatedJsxName(getTextOfJsxAttributeName(prop.name))) continue; + yield { errorNode: prop.name, innerExpression: prop.initializer, nameType: getStringLiteralType(getTextOfJsxAttributeName(prop.name)) }; + } + } + + function* generateJsxChildren(node: JsxElement, getInvalidTextDiagnostic: () => DiagnosticMessage): ElaborationIterator { + if (!length(node.children)) return; + let memberOffset = 0; + for (let i = 0; i < node.children.length; i++) { + const child = node.children[i]; + const nameType = getNumberLiteralType(i - memberOffset); + const elem = getElaborationElementForJsxChild(child, nameType, getInvalidTextDiagnostic); + if (elem) { + yield elem; + } + else { + memberOffset++; + } + } + } + + function getElaborationElementForJsxChild(child: JsxChild, nameType: LiteralType, getInvalidTextDiagnostic: () => DiagnosticMessage) { + switch (child.kind) { + case SyntaxKind.JsxExpression: + // child is of the type of the expression + return { errorNode: child, innerExpression: child.expression, nameType }; + case SyntaxKind.JsxText: + if (child.containsOnlyTriviaWhiteSpaces) { + break; // Whitespace only jsx text isn't real jsx text + } + // child is a string + return { errorNode: child, innerExpression: undefined, nameType, errorMessage: getInvalidTextDiagnostic() }; + case SyntaxKind.JsxElement: + case SyntaxKind.JsxSelfClosingElement: + case SyntaxKind.JsxFragment: + // child is of type JSX.Element + return { errorNode: child, innerExpression: child, nameType }; + default: + return Debug.assertNever(child, "Found invalid jsx child"); + } + } + + function elaborateJsxComponents( + node: JsxAttributes, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + let result = elaborateElementwise(generateJsxAttributes(node), source, target, relation, containingMessageChain, errorOutputContainer); + let invalidTextDiagnostic: DiagnosticMessage | undefined; + if (isJsxOpeningElement(node.parent) && isJsxElement(node.parent.parent)) { + const containingElement = node.parent.parent; + const childPropName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + const childrenPropName = childPropName === undefined ? "children" : unescapeLeadingUnderscores(childPropName); + const childrenNameType = getStringLiteralType(childrenPropName); + const childrenTargetType = getIndexedAccessType(target, childrenNameType); + const validChildren = getSemanticJsxChildren(containingElement.children); + if (!length(validChildren)) { + return result; + } + const moreThanOneRealChildren = length(validChildren) > 1; + let arrayLikeTargetParts: Type; + let nonArrayLikeTargetParts: Type; + const iterableType = getGlobalIterableType(/*reportErrors*/ false); + if (iterableType !== emptyGenericType) { + const anyIterable = createIterableType(anyType); + arrayLikeTargetParts = filterType(childrenTargetType, t => isTypeAssignableTo(t, anyIterable)); + nonArrayLikeTargetParts = filterType(childrenTargetType, t => !isTypeAssignableTo(t, anyIterable)); + } + else { + arrayLikeTargetParts = filterType(childrenTargetType, isArrayOrTupleLikeType); + nonArrayLikeTargetParts = filterType(childrenTargetType, t => !isArrayOrTupleLikeType(t)); + } + if (moreThanOneRealChildren) { + if (arrayLikeTargetParts !== neverType) { + const realSource = createTupleType(checkJsxChildren(containingElement, CheckMode.Normal)); + const children = generateJsxChildren(containingElement, getInvalidTextualChildDiagnostic); + result = elaborateIterableOrArrayLikeTargetElementwise(children, realSource, arrayLikeTargetParts, relation, containingMessageChain, errorOutputContainer) || result; + } + else if (!isTypeRelatedTo(getIndexedAccessType(source, childrenNameType), childrenTargetType, relation)) { + // arity mismatch + result = true; + const diag = error( + containingElement.openingElement.tagName, + Diagnostics.This_JSX_tag_s_0_prop_expects_a_single_child_of_type_1_but_multiple_children_were_provided, + childrenPropName, + typeToString(childrenTargetType), + ); + if (errorOutputContainer && errorOutputContainer.skipLogging) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + } + } + else { + if (nonArrayLikeTargetParts !== neverType) { + const child = validChildren[0]; + const elem = getElaborationElementForJsxChild(child, childrenNameType, getInvalidTextualChildDiagnostic); + if (elem) { + result = elaborateElementwise( + (function* () { + yield elem; + })(), + source, + target, + relation, + containingMessageChain, + errorOutputContainer, + ) || result; + } + } + else if (!isTypeRelatedTo(getIndexedAccessType(source, childrenNameType), childrenTargetType, relation)) { + // arity mismatch + result = true; + const diag = error( + containingElement.openingElement.tagName, + Diagnostics.This_JSX_tag_s_0_prop_expects_type_1_which_requires_multiple_children_but_only_a_single_child_was_provided, + childrenPropName, + typeToString(childrenTargetType), + ); + if (errorOutputContainer && errorOutputContainer.skipLogging) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + } + } + } + return result; + + function getInvalidTextualChildDiagnostic() { + if (!invalidTextDiagnostic) { + const tagNameText = getTextOfNode(node.parent.tagName); + const childPropName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + const childrenPropName = childPropName === undefined ? "children" : unescapeLeadingUnderscores(childPropName); + const childrenTargetType = getIndexedAccessType(target, getStringLiteralType(childrenPropName)); + const diagnostic = Diagnostics._0_components_don_t_accept_text_as_child_elements_Text_in_JSX_has_the_type_string_but_the_expected_type_of_1_is_2; + invalidTextDiagnostic = { ...diagnostic, key: "!!ALREADY FORMATTED!!", message: formatMessage(diagnostic, tagNameText, childrenPropName, typeToString(childrenTargetType)) }; + } + return invalidTextDiagnostic; + } + } + + function* generateLimitedTupleElements(node: ArrayLiteralExpression, target: Type): ElaborationIterator { + const len = length(node.elements); + if (!len) return; + for (let i = 0; i < len; i++) { + // Skip elements which do not exist in the target - a length error on the tuple overall is likely better than an error on a mismatched index signature + if (isTupleLikeType(target) && !getPropertyOfType(target, ("" + i) as __String)) continue; + const elem = node.elements[i]; + if (isOmittedExpression(elem)) continue; + const nameType = getNumberLiteralType(i); + const checkNode = getEffectiveCheckNode(elem); + yield { errorNode: checkNode, innerExpression: checkNode, nameType }; + } + } + + function elaborateArrayLiteral( + node: ArrayLiteralExpression, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + if (target.flags & (TypeFlags.Primitive | TypeFlags.Never)) return false; + if (isTupleLikeType(source)) { + return elaborateElementwise(generateLimitedTupleElements(node, target), source, target, relation, containingMessageChain, errorOutputContainer); + } + // recreate a tuple from the elements, if possible + // Since we're re-doing the expression type, we need to reapply the contextual type + pushContextualType(node, target, /*isCache*/ false); + const tupleizedType = checkArrayLiteral(node, CheckMode.Contextual, /*forceTuple*/ true); + popContextualType(); + if (isTupleLikeType(tupleizedType)) { + return elaborateElementwise(generateLimitedTupleElements(node, target), tupleizedType, target, relation, containingMessageChain, errorOutputContainer); + } + return false; + } + + function* generateObjectLiteralElements(node: ObjectLiteralExpression): ElaborationIterator { + if (!length(node.properties)) return; + for (const prop of node.properties) { + if (isSpreadAssignment(prop)) continue; + const type = getLiteralTypeFromProperty(getSymbolOfDeclaration(prop), TypeFlags.StringOrNumberLiteralOrUnique); + if (!type || (type.flags & TypeFlags.Never)) { + continue; + } + switch (prop.kind) { + case SyntaxKind.SetAccessor: + case SyntaxKind.GetAccessor: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.ShorthandPropertyAssignment: + yield { errorNode: prop.name, innerExpression: undefined, nameType: type }; + break; + case SyntaxKind.PropertyAssignment: + yield { errorNode: prop.name, innerExpression: prop.initializer, nameType: type, errorMessage: isComputedNonLiteralName(prop.name) ? Diagnostics.Type_of_computed_property_s_value_is_0_which_is_not_assignable_to_type_1 : undefined }; + break; + default: + Debug.assertNever(prop); + } + } + } + + function elaborateObjectLiteral( + node: ObjectLiteralExpression, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + if (target.flags & (TypeFlags.Primitive | TypeFlags.Never)) return false; + return elaborateElementwise(generateObjectLiteralElements(node), source, target, relation, containingMessageChain, errorOutputContainer); + } + + /** + * This is *not* a bi-directional relationship. + * If one needs to check both directions for comparability, use a second call to this function or 'isTypeComparableTo'. + */ + function checkTypeComparableTo(source: Type, target: Type, errorNode: Node, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined): boolean { + return checkTypeRelatedTo(source, target, comparableRelation, errorNode, headMessage, containingMessageChain); + } + + function isSignatureAssignableTo(source: Signature, target: Signature, ignoreReturnTypes: boolean): boolean { + return compareSignaturesRelated(source, target, ignoreReturnTypes ? SignatureCheckMode.IgnoreReturnTypes : SignatureCheckMode.None, /*reportErrors*/ false, /*errorReporter*/ undefined, /*incompatibleErrorReporter*/ undefined, compareTypesAssignable, /*reportUnreliableMarkers*/ undefined) !== Ternary.False; + } + + type ErrorReporter = (message: DiagnosticMessage, ...args: DiagnosticArguments) => void; + + /** + * Returns true if `s` is `(...args: A) => R` where `A` is `any`, `any[]`, `never`, or `never[]`, and `R` is `any` or `unknown`. + */ + function isTopSignature(s: Signature) { + if (!s.typeParameters && (!s.thisParameter || isTypeAny(getTypeOfParameter(s.thisParameter))) && s.parameters.length === 1 && signatureHasRestParameter(s)) { + const paramType = getTypeOfParameter(s.parameters[0]); + const restType = isArrayType(paramType) ? getTypeArguments(paramType)[0] : paramType; + return !!(restType.flags & (TypeFlags.Any | TypeFlags.Never) && getReturnTypeOfSignature(s).flags & TypeFlags.AnyOrUnknown); + } + return false; + } + + /** + * See signatureRelatedTo, compareSignaturesIdentical + */ + function compareSignaturesRelated(source: Signature, target: Signature, checkMode: SignatureCheckMode, reportErrors: boolean, errorReporter: ErrorReporter | undefined, incompatibleErrorReporter: ((source: Type, target: Type) => void) | undefined, compareTypes: TypeComparer, reportUnreliableMarkers: TypeMapper | undefined): Ternary { + // TODO (drosen): De-duplicate code between related functions. + if (source === target) { + return Ternary.True; + } + + if (!(checkMode & SignatureCheckMode.StrictTopSignature && isTopSignature(source)) && isTopSignature(target)) { + return Ternary.True; + } + if (checkMode & SignatureCheckMode.StrictTopSignature && isTopSignature(source) && !isTopSignature(target)) { + return Ternary.False; + } + + const targetCount = getParameterCount(target); + const sourceHasMoreParameters = !hasEffectiveRestParameter(target) && + (checkMode & SignatureCheckMode.StrictArity ? hasEffectiveRestParameter(source) || getParameterCount(source) > targetCount : getMinArgumentCount(source) > targetCount); + if (sourceHasMoreParameters) { + if (reportErrors && !(checkMode & SignatureCheckMode.StrictArity)) { + // the second condition should be redundant, because there is no error reporting when comparing signatures by strict arity + // since it is only done for subtype reduction + errorReporter!(Diagnostics.Target_signature_provides_too_few_arguments_Expected_0_or_more_but_got_1, getMinArgumentCount(source), targetCount); + } + return Ternary.False; + } + + if (source.typeParameters && source.typeParameters !== target.typeParameters) { + target = getCanonicalSignature(target); + source = instantiateSignatureInContextOf(source, target, /*inferenceContext*/ undefined, compareTypes); + } + + const sourceCount = getParameterCount(source); + const sourceRestType = getNonArrayRestType(source); + const targetRestType = getNonArrayRestType(target); + if (sourceRestType || targetRestType) { + void instantiateType(sourceRestType || targetRestType, reportUnreliableMarkers); + } + + const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown; + const strictVariance = !(checkMode & SignatureCheckMode.Callback) && strictFunctionTypes && kind !== SyntaxKind.MethodDeclaration && + kind !== SyntaxKind.MethodSignature && kind !== SyntaxKind.Constructor; + let result = Ternary.True; + + const sourceThisType = getThisTypeOfSignature(source); + if (sourceThisType && sourceThisType !== voidType) { + const targetThisType = getThisTypeOfSignature(target); + if (targetThisType) { + // void sources are assignable to anything. + const related = !strictVariance && compareTypes(sourceThisType, targetThisType, /*reportErrors*/ false) + || compareTypes(targetThisType, sourceThisType, reportErrors); + if (!related) { + if (reportErrors) { + errorReporter!(Diagnostics.The_this_types_of_each_signature_are_incompatible); + } + return Ternary.False; + } + result &= related; + } + } + + const paramCount = sourceRestType || targetRestType ? Math.min(sourceCount, targetCount) : Math.max(sourceCount, targetCount); + const restIndex = sourceRestType || targetRestType ? paramCount - 1 : -1; + + for (let i = 0; i < paramCount; i++) { + const sourceType = i === restIndex ? getRestOrAnyTypeAtPosition(source, i) : tryGetTypeAtPosition(source, i); + const targetType = i === restIndex ? getRestOrAnyTypeAtPosition(target, i) : tryGetTypeAtPosition(target, i); + if (sourceType && targetType && (sourceType !== targetType || checkMode & SignatureCheckMode.StrictArity)) { + // In order to ensure that any generic type Foo is at least co-variant with respect to T no matter + // how Foo uses T, we need to relate parameters bi-variantly (given that parameters are input positions, + // they naturally relate only contra-variantly). However, if the source and target parameters both have + // function types with a single call signature, we know we are relating two callback parameters. In + // that case it is sufficient to only relate the parameters of the signatures co-variantly because, + // similar to return values, callback parameters are output positions. This means that a Promise, + // where T is used only in callback parameter positions, will be co-variant (as opposed to bi-variant) + // with respect to T. + const sourceSig = checkMode & SignatureCheckMode.Callback || isInstantiatedGenericParameter(source, i) ? undefined : getSingleCallSignature(getNonNullableType(sourceType)); + const targetSig = checkMode & SignatureCheckMode.Callback || isInstantiatedGenericParameter(target, i) ? undefined : getSingleCallSignature(getNonNullableType(targetType)); + const callbacks = sourceSig && targetSig && !getTypePredicateOfSignature(sourceSig) && !getTypePredicateOfSignature(targetSig) && + getTypeFacts(sourceType, TypeFacts.IsUndefinedOrNull) === getTypeFacts(targetType, TypeFacts.IsUndefinedOrNull); + let related = callbacks ? + compareSignaturesRelated(targetSig, sourceSig, (checkMode & SignatureCheckMode.StrictArity) | (strictVariance ? SignatureCheckMode.StrictCallback : SignatureCheckMode.BivariantCallback), reportErrors, errorReporter, incompatibleErrorReporter, compareTypes, reportUnreliableMarkers) : + !(checkMode & SignatureCheckMode.Callback) && !strictVariance && compareTypes(sourceType, targetType, /*reportErrors*/ false) || compareTypes(targetType, sourceType, reportErrors); + // With strict arity, (x: number | undefined) => void is a subtype of (x?: number | undefined) => void + if (related && checkMode & SignatureCheckMode.StrictArity && i >= getMinArgumentCount(source) && i < getMinArgumentCount(target) && compareTypes(sourceType, targetType, /*reportErrors*/ false)) { + related = Ternary.False; + } + if (!related) { + if (reportErrors) { + errorReporter!(Diagnostics.Types_of_parameters_0_and_1_are_incompatible, unescapeLeadingUnderscores(getParameterNameAtPosition(source, i)), unescapeLeadingUnderscores(getParameterNameAtPosition(target, i))); + } + return Ternary.False; + } + result &= related; + } + } + + if (!(checkMode & SignatureCheckMode.IgnoreReturnTypes)) { + // If a signature resolution is already in-flight, skip issuing a circularity error + // here and just use the `any` type directly + const targetReturnType = isResolvingReturnTypeOfSignature(target) ? anyType + : target.declaration && isJSConstructor(target.declaration) ? getDeclaredTypeOfClassOrInterface(getMergedSymbol(target.declaration.symbol)) + : getReturnTypeOfSignature(target); + if (targetReturnType === voidType || targetReturnType === anyType) { + return result; + } + const sourceReturnType = isResolvingReturnTypeOfSignature(source) ? anyType + : source.declaration && isJSConstructor(source.declaration) ? getDeclaredTypeOfClassOrInterface(getMergedSymbol(source.declaration.symbol)) + : getReturnTypeOfSignature(source); + + // The following block preserves behavior forbidding boolean returning functions from being assignable to type guard returning functions + const targetTypePredicate = getTypePredicateOfSignature(target); + if (targetTypePredicate) { + const sourceTypePredicate = getTypePredicateOfSignature(source); + if (sourceTypePredicate) { + result &= compareTypePredicateRelatedTo(sourceTypePredicate, targetTypePredicate, reportErrors, errorReporter, compareTypes); + } + else if (isIdentifierTypePredicate(targetTypePredicate) || isThisTypePredicate(targetTypePredicate)) { + if (reportErrors) { + errorReporter!(Diagnostics.Signature_0_must_be_a_type_predicate, signatureToString(source)); + } + return Ternary.False; + } + } + else { + // When relating callback signatures, we still need to relate return types bi-variantly as otherwise + // the containing type wouldn't be co-variant. For example, interface Foo { add(cb: () => T): void } + // wouldn't be co-variant for T without this rule. + result &= checkMode & SignatureCheckMode.BivariantCallback && compareTypes(targetReturnType, sourceReturnType, /*reportErrors*/ false) || + compareTypes(sourceReturnType, targetReturnType, reportErrors); + if (!result && reportErrors && incompatibleErrorReporter) { + incompatibleErrorReporter(sourceReturnType, targetReturnType); + } + } + } + + return result; + } + + function compareTypePredicateRelatedTo( + source: TypePredicate, + target: TypePredicate, + reportErrors: boolean, + errorReporter: ErrorReporter | undefined, + compareTypes: (s: Type, t: Type, reportErrors?: boolean) => Ternary, + ): Ternary { + if (source.kind !== target.kind) { + if (reportErrors) { + errorReporter!(Diagnostics.A_this_based_type_guard_is_not_compatible_with_a_parameter_based_type_guard); + errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); + } + return Ternary.False; + } + + if (source.kind === TypePredicateKind.Identifier || source.kind === TypePredicateKind.AssertsIdentifier) { + if (source.parameterIndex !== (target as IdentifierTypePredicate).parameterIndex) { + if (reportErrors) { + errorReporter!(Diagnostics.Parameter_0_is_not_in_the_same_position_as_parameter_1, source.parameterName, (target as IdentifierTypePredicate).parameterName); + errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); + } + return Ternary.False; + } + } + + const related = source.type === target.type ? Ternary.True : + source.type && target.type ? compareTypes(source.type, target.type, reportErrors) : + Ternary.False; + if (related === Ternary.False && reportErrors) { + errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); + } + return related; + } + + function isImplementationCompatibleWithOverload(implementation: Signature, overload: Signature): boolean { + const erasedSource = getErasedSignature(implementation); + const erasedTarget = getErasedSignature(overload); + + // First see if the return types are compatible in either direction. + const sourceReturnType = getReturnTypeOfSignature(erasedSource); + const targetReturnType = getReturnTypeOfSignature(erasedTarget); + if ( + targetReturnType === voidType + || isTypeRelatedTo(targetReturnType, sourceReturnType, assignableRelation) + || isTypeRelatedTo(sourceReturnType, targetReturnType, assignableRelation) + ) { + return isSignatureAssignableTo(erasedSource, erasedTarget, /*ignoreReturnTypes*/ true); + } + + return false; + } + + function isEmptyResolvedType(t: ResolvedType) { + return t !== anyFunctionType && + t.properties.length === 0 && + t.callSignatures.length === 0 && + t.constructSignatures.length === 0 && + t.indexInfos.length === 0; + } + + function isEmptyObjectType(type: Type): boolean { + return type.flags & TypeFlags.Object ? !isGenericMappedType(type) && isEmptyResolvedType(resolveStructuredTypeMembers(type as ObjectType)) : + type.flags & TypeFlags.NonPrimitive ? true : + type.flags & TypeFlags.Union ? some((type as UnionType).types, isEmptyObjectType) : + type.flags & TypeFlags.Intersection ? every((type as UnionType).types, isEmptyObjectType) : + false; + } + + function isEmptyAnonymousObjectType(type: Type) { + return !!(getObjectFlags(type) & ObjectFlags.Anonymous && ( + (type as ResolvedType).members && isEmptyResolvedType(type as ResolvedType) || + type.symbol && type.symbol.flags & SymbolFlags.TypeLiteral && getMembersOfSymbol(type.symbol).size === 0 + )); + } + + function isUnknownLikeUnionType(type: Type) { + if (strictNullChecks && type.flags & TypeFlags.Union) { + if (!((type as UnionType).objectFlags & ObjectFlags.IsUnknownLikeUnionComputed)) { + const types = (type as UnionType).types; + (type as UnionType).objectFlags |= ObjectFlags.IsUnknownLikeUnionComputed | (types.length >= 3 && types[0].flags & TypeFlags.Undefined && + types[1].flags & TypeFlags.Null && some(types, isEmptyAnonymousObjectType) ? ObjectFlags.IsUnknownLikeUnion : 0); + } + return !!((type as UnionType).objectFlags & ObjectFlags.IsUnknownLikeUnion); + } + return false; + } + + function containsUndefinedType(type: Type) { + return !!((type.flags & TypeFlags.Union ? (type as UnionType).types[0] : type).flags & TypeFlags.Undefined); + } + + function isStringIndexSignatureOnlyType(type: Type): boolean { + return type.flags & TypeFlags.Object && !isGenericMappedType(type) && getPropertiesOfType(type).length === 0 && getIndexInfosOfType(type).length === 1 && !!getIndexInfoOfType(type, stringType) || + type.flags & TypeFlags.UnionOrIntersection && every((type as UnionOrIntersectionType).types, isStringIndexSignatureOnlyType) || + false; + } + + function isEnumTypeRelatedTo(source: Symbol, target: Symbol, errorReporter?: ErrorReporter) { + const sourceSymbol = source.flags & SymbolFlags.EnumMember ? getParentOfSymbol(source)! : source; + const targetSymbol = target.flags & SymbolFlags.EnumMember ? getParentOfSymbol(target)! : target; + if (sourceSymbol === targetSymbol) { + return true; + } + if (sourceSymbol.escapedName !== targetSymbol.escapedName || !(sourceSymbol.flags & SymbolFlags.RegularEnum) || !(targetSymbol.flags & SymbolFlags.RegularEnum)) { + return false; + } + const id = getSymbolId(sourceSymbol) + "," + getSymbolId(targetSymbol); + const entry = enumRelation.get(id); + if (entry !== undefined && !(!(entry & RelationComparisonResult.Reported) && entry & RelationComparisonResult.Failed && errorReporter)) { + return !!(entry & RelationComparisonResult.Succeeded); + } + const targetEnumType = getTypeOfSymbol(targetSymbol); + for (const sourceProperty of getPropertiesOfType(getTypeOfSymbol(sourceSymbol))) { + if (sourceProperty.flags & SymbolFlags.EnumMember) { + const targetProperty = getPropertyOfType(targetEnumType, sourceProperty.escapedName); + if (!targetProperty || !(targetProperty.flags & SymbolFlags.EnumMember)) { + if (errorReporter) { + errorReporter(Diagnostics.Property_0_is_missing_in_type_1, symbolName(sourceProperty), typeToString(getDeclaredTypeOfSymbol(targetSymbol), /*enclosingDeclaration*/ undefined, TypeFormatFlags.UseFullyQualifiedType)); + enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); + } + else { + enumRelation.set(id, RelationComparisonResult.Failed); + } + return false; + } + const sourceValue = getEnumMemberValue(getDeclarationOfKind(sourceProperty, SyntaxKind.EnumMember)!).value; + const targetValue = getEnumMemberValue(getDeclarationOfKind(targetProperty, SyntaxKind.EnumMember)!).value; + if (sourceValue !== targetValue) { + const sourceIsString = typeof sourceValue === "string"; + const targetIsString = typeof targetValue === "string"; + + // If we have 2 enums with *known* values that differ, they are incompatible. + if (sourceValue !== undefined && targetValue !== undefined) { + if (!errorReporter) { + enumRelation.set(id, RelationComparisonResult.Failed); + } + else { + const escapedSource = sourceIsString ? `"${escapeString(sourceValue)}"` : sourceValue; + const escapedTarget = targetIsString ? `"${escapeString(targetValue)}"` : targetValue; + errorReporter(Diagnostics.Each_declaration_of_0_1_differs_in_its_value_where_2_was_expected_but_3_was_given, symbolName(targetSymbol), symbolName(targetProperty), escapedTarget, escapedSource); + enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); + } + return false; + } + + // At this point we know that at least one of the values is 'undefined'. + // This may mean that we have an opaque member from an ambient enum declaration, + // or that we were not able to calculate it (which is basically an error). + // + // Either way, we can assume that it's numeric. + // If the other is a string, we have a mismatch in types. + if (sourceIsString || targetIsString) { + if (!errorReporter) { + enumRelation.set(id, RelationComparisonResult.Failed); + } + else { + const knownStringValue = sourceValue ?? targetValue; + Debug.assert(typeof knownStringValue === "string"); + const escapedValue = `"${escapeString(knownStringValue)}"`; + errorReporter(Diagnostics.One_value_of_0_1_is_the_string_2_and_the_other_is_assumed_to_be_an_unknown_numeric_value, symbolName(targetSymbol), symbolName(targetProperty), escapedValue); + enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); + } + return false; + } + } + } + } + enumRelation.set(id, RelationComparisonResult.Succeeded); + return true; + } + + function isSimpleTypeRelatedTo(source: Type, target: Type, relation: Map, errorReporter?: ErrorReporter) { + const s = source.flags; + const t = target.flags; + if (t & TypeFlags.Any || s & TypeFlags.Never || source === wildcardType) return true; + if (t & TypeFlags.Unknown && !(relation === strictSubtypeRelation && s & TypeFlags.Any)) return true; + if (t & TypeFlags.Never) return false; + if (s & TypeFlags.StringLike && t & TypeFlags.String) return true; + if ( + s & TypeFlags.StringLiteral && s & TypeFlags.EnumLiteral && + t & TypeFlags.StringLiteral && !(t & TypeFlags.EnumLiteral) && + (source as StringLiteralType).value === (target as StringLiteralType).value + ) return true; + if (s & TypeFlags.NumberLike && t & TypeFlags.Number) return true; + if ( + s & TypeFlags.NumberLiteral && s & TypeFlags.EnumLiteral && + t & TypeFlags.NumberLiteral && !(t & TypeFlags.EnumLiteral) && + (source as NumberLiteralType).value === (target as NumberLiteralType).value + ) return true; + if (s & TypeFlags.BigIntLike && t & TypeFlags.BigInt) return true; + if (s & TypeFlags.BooleanLike && t & TypeFlags.Boolean) return true; + if (s & TypeFlags.ESSymbolLike && t & TypeFlags.ESSymbol) return true; + if ( + s & TypeFlags.Enum && t & TypeFlags.Enum && source.symbol.escapedName === target.symbol.escapedName && + isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter) + ) return true; + if (s & TypeFlags.EnumLiteral && t & TypeFlags.EnumLiteral) { + if (s & TypeFlags.Union && t & TypeFlags.Union && isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter)) return true; + if ( + s & TypeFlags.Literal && t & TypeFlags.Literal && (source as LiteralType).value === (target as LiteralType).value && + isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter) + ) return true; + } + // In non-strictNullChecks mode, `undefined` and `null` are assignable to anything except `never`. + // Since unions and intersections may reduce to `never`, we exclude them here. + if (s & TypeFlags.Undefined && (!strictNullChecks && !(t & TypeFlags.UnionOrIntersection) || t & (TypeFlags.Undefined | TypeFlags.Void))) return true; + if (s & TypeFlags.Null && (!strictNullChecks && !(t & TypeFlags.UnionOrIntersection) || t & TypeFlags.Null)) return true; + if (s & TypeFlags.Object && t & TypeFlags.NonPrimitive && !(relation === strictSubtypeRelation && isEmptyAnonymousObjectType(source) && !(getObjectFlags(source) & ObjectFlags.FreshLiteral))) return true; + if (relation === assignableRelation || relation === comparableRelation) { + if (s & TypeFlags.Any) return true; + // Type number is assignable to any computed numeric enum type or any numeric enum literal type, and + // a numeric literal type is assignable any computed numeric enum type or any numeric enum literal type + // with a matching value. These rules exist such that enums can be used for bit-flag purposes. + if (s & TypeFlags.Number && (t & TypeFlags.Enum || t & TypeFlags.NumberLiteral && t & TypeFlags.EnumLiteral)) return true; + if ( + s & TypeFlags.NumberLiteral && !(s & TypeFlags.EnumLiteral) && (t & TypeFlags.Enum || + t & TypeFlags.NumberLiteral && t & TypeFlags.EnumLiteral && + (source as NumberLiteralType).value === (target as NumberLiteralType).value) + ) return true; + // Anything is assignable to a union containing undefined, null, and {} + if (isUnknownLikeUnionType(target)) return true; + } + return false; + } + + function isTypeRelatedTo(source: Type, target: Type, relation: Map) { + if (isFreshLiteralType(source)) { + source = (source as FreshableType).regularType; + } + if (isFreshLiteralType(target)) { + target = (target as FreshableType).regularType; + } + if (source === target) { + return true; + } + if (relation !== identityRelation) { + if (relation === comparableRelation && !(target.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(target, source, relation) || isSimpleTypeRelatedTo(source, target, relation)) { + return true; + } + } + else if (!((source.flags | target.flags) & (TypeFlags.UnionOrIntersection | TypeFlags.IndexedAccess | TypeFlags.Conditional | TypeFlags.Substitution))) { + // We have excluded types that may simplify to other forms, so types must have identical flags + if (source.flags !== target.flags) return false; + if (source.flags & TypeFlags.Singleton) return true; + } + if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) { + const related = relation.get(getRelationKey(source, target, IntersectionState.None, relation, /*ignoreConstraints*/ false)); + if (related !== undefined) { + return !!(related & RelationComparisonResult.Succeeded); + } + } + if (source.flags & TypeFlags.StructuredOrInstantiable || target.flags & TypeFlags.StructuredOrInstantiable) { + return checkTypeRelatedTo(source, target, relation, /*errorNode*/ undefined); + } + return false; + } + + function isIgnoredJsxProperty(source: Type, sourceProp: Symbol) { + return getObjectFlags(source) & ObjectFlags.JsxAttributes && isHyphenatedJsxName(sourceProp.escapedName); + } + + function getNormalizedType(type: Type, writing: boolean): Type { + while (true) { + const t = isFreshLiteralType(type) ? (type as FreshableType).regularType : + isGenericTupleType(type) ? getNormalizedTupleType(type, writing) : + getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).node ? createTypeReference((type as TypeReference).target, getTypeArguments(type as TypeReference)) : getSingleBaseForNonAugmentingSubtype(type) || type : + type.flags & TypeFlags.UnionOrIntersection ? getNormalizedUnionOrIntersectionType(type as UnionOrIntersectionType, writing) : + type.flags & TypeFlags.Substitution ? writing ? (type as SubstitutionType).baseType : getSubstitutionIntersection(type as SubstitutionType) : + type.flags & TypeFlags.Simplifiable ? getSimplifiedType(type, writing) : + type; + if (t === type) return t; + type = t; + } + } + + function getNormalizedUnionOrIntersectionType(type: UnionOrIntersectionType, writing: boolean) { + const reduced = getReducedType(type); + if (reduced !== type) { + return reduced; + } + if (type.flags & TypeFlags.Intersection && shouldNormalizeIntersection(type as IntersectionType)) { + // Normalization handles cases like + // Partial[K] & ({} | null) ==> + // Partial[K] & {} | Partial[K} & null ==> + // (T[K] | undefined) & {} | (T[K] | undefined) & null ==> + // T[K] & {} | undefined & {} | T[K] & null | undefined & null ==> + // T[K] & {} | T[K] & null + const normalizedTypes = sameMap(type.types, t => getNormalizedType(t, writing)); + if (normalizedTypes !== type.types) { + return getIntersectionType(normalizedTypes); + } + } + return type; + } + + function shouldNormalizeIntersection(type: IntersectionType) { + let hasInstantiable = false; + let hasNullableOrEmpty = false; + for (const t of type.types) { + hasInstantiable ||= !!(t.flags & TypeFlags.Instantiable); + hasNullableOrEmpty ||= !!(t.flags & TypeFlags.Nullable) || isEmptyAnonymousObjectType(t); + if (hasInstantiable && hasNullableOrEmpty) return true; + } + return false; + } + + function getNormalizedTupleType(type: TupleTypeReference, writing: boolean): Type { + const elements = getElementTypes(type); + const normalizedElements = sameMap(elements, t => t.flags & TypeFlags.Simplifiable ? getSimplifiedType(t, writing) : t); + return elements !== normalizedElements ? createNormalizedTupleType(type.target, normalizedElements) : type; + } + + /** + * Checks if 'source' is related to 'target' (e.g.: is a assignable to). + * @param source The left-hand-side of the relation. + * @param target The right-hand-side of the relation. + * @param relation The relation considered. One of 'identityRelation', 'subtypeRelation', 'assignableRelation', or 'comparableRelation'. + * Used as both to determine which checks are performed and as a cache of previously computed results. + * @param errorNode The suggested node upon which all errors will be reported, if defined. This may or may not be the actual node used. + * @param headMessage If the error chain should be prepended by a head message, then headMessage will be used. + * @param containingMessageChain A chain of errors to prepend any new errors found. + * @param errorOutputContainer Return the diagnostic. Do not log if 'skipLogging' is truthy. + */ + function checkTypeRelatedTo( + source: Type, + target: Type, + relation: Map, + errorNode: Node | undefined, + headMessage?: DiagnosticMessage, + containingMessageChain?: () => DiagnosticMessageChain | undefined, + errorOutputContainer?: { errors?: Diagnostic[]; skipLogging?: boolean; }, + ): boolean { + let errorInfo: DiagnosticMessageChain | undefined; + let relatedInfo: [DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined; + let maybeKeys: string[]; + let maybeKeysSet: Set; + let sourceStack: Type[]; + let targetStack: Type[]; + let maybeCount = 0; + let sourceDepth = 0; + let targetDepth = 0; + let expandingFlags = ExpandingFlags.None; + let overflow = false; + let overrideNextErrorInfo = 0; // How many `reportRelationError` calls should be skipped in the elaboration pyramid + let skipParentCounter = 0; // How many errors should be skipped 'above' in the elaboration pyramid + let lastSkippedInfo: [Type, Type] | undefined; + let incompatibleStack: DiagnosticAndArguments[] | undefined; + // In Node.js, the maximum number of elements in a map is 2^24. We limit the number of entries an invocation + // of checkTypeRelatedTo can add to a relation to 1/8th of its remaining capacity. + let relationCount = (16_000_000 - relation.size) >> 3; + + Debug.assert(relation !== identityRelation || !errorNode, "no error reporting in identity checking"); + + const result = isRelatedTo(source, target, RecursionFlags.Both, /*reportErrors*/ !!errorNode, headMessage); + if (incompatibleStack) { + reportIncompatibleStack(); + } + if (overflow) { + // Record this relation as having failed such that we don't attempt the overflowing operation again. + const id = getRelationKey(source, target, /*intersectionState*/ IntersectionState.None, relation, /*ignoreConstraints*/ false); + relation.set(id, RelationComparisonResult.Reported | RelationComparisonResult.Failed); + tracing?.instant(tracing.Phase.CheckTypes, "checkTypeRelatedTo_DepthLimit", { sourceId: source.id, targetId: target.id, depth: sourceDepth, targetDepth }); + const message = relationCount <= 0 ? + Diagnostics.Excessive_complexity_comparing_types_0_and_1 : + Diagnostics.Excessive_stack_depth_comparing_types_0_and_1; + const diag = error(errorNode || currentNode, message, typeToString(source), typeToString(target)); + if (errorOutputContainer) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + } + else if (errorInfo) { + if (containingMessageChain) { + const chain = containingMessageChain(); + if (chain) { + concatenateDiagnosticMessageChains(chain, errorInfo); + errorInfo = chain; + } + } + + let relatedInformation: DiagnosticRelatedInformation[] | undefined; + // Check if we should issue an extra diagnostic to produce a quickfix for a slightly incorrect import statement + if (headMessage && errorNode && !result && source.symbol) { + const links = getSymbolLinks(source.symbol); + if (links.originatingImport && !isImportCall(links.originatingImport)) { + const helpfulRetry = checkTypeRelatedTo(getTypeOfSymbol(links.target!), target, relation, /*errorNode*/ undefined); + if (helpfulRetry) { + // Likely an incorrect import. Issue a helpful diagnostic to produce a quickfix to change the import + const diag = createDiagnosticForNode(links.originatingImport, Diagnostics.Type_originates_at_this_import_A_namespace_style_import_cannot_be_called_or_constructed_and_will_cause_a_failure_at_runtime_Consider_using_a_default_import_or_import_require_here_instead); + relatedInformation = append(relatedInformation, diag); // Cause the error to appear with the error that triggered it + } + } + } + const diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorNode!), errorNode!, errorInfo, relatedInformation); + if (relatedInfo) { + addRelatedInfo(diag, ...relatedInfo); + } + if (errorOutputContainer) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + if (!errorOutputContainer || !errorOutputContainer.skipLogging) { + diagnostics.add(diag); + } + } + if (errorNode && errorOutputContainer && errorOutputContainer.skipLogging && result === Ternary.False) { + Debug.assert(!!errorOutputContainer.errors, "missed opportunity to interact with error."); + } + + return result !== Ternary.False; + + function resetErrorInfo(saved: ReturnType) { + errorInfo = saved.errorInfo; + lastSkippedInfo = saved.lastSkippedInfo; + incompatibleStack = saved.incompatibleStack; + overrideNextErrorInfo = saved.overrideNextErrorInfo; + skipParentCounter = saved.skipParentCounter; + relatedInfo = saved.relatedInfo; + } + + function captureErrorCalculationState() { + return { + errorInfo, + lastSkippedInfo, + incompatibleStack: incompatibleStack?.slice(), + overrideNextErrorInfo, + skipParentCounter, + relatedInfo: relatedInfo?.slice() as [DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined, + }; + } + + function reportIncompatibleError(message: DiagnosticMessage, ...args: DiagnosticArguments) { + overrideNextErrorInfo++; // Suppress the next relation error + lastSkippedInfo = undefined; // Reset skipped info cache + (incompatibleStack ||= []).push([message, ...args]); + } + + function reportIncompatibleStack() { + const stack = incompatibleStack || []; + incompatibleStack = undefined; + const info = lastSkippedInfo; + lastSkippedInfo = undefined; + if (stack.length === 1) { + reportError(...stack[0]); + if (info) { + // Actually do the last relation error + reportRelationError(/*message*/ undefined, ...info); + } + return; + } + // The first error will be the innermost, while the last will be the outermost - so by popping off the end, + // we can build from left to right + let path = ""; + const secondaryRootErrors: DiagnosticAndArguments[] = []; + while (stack.length) { + const [msg, ...args] = stack.pop()!; + switch (msg.code) { + case Diagnostics.Types_of_property_0_are_incompatible.code: { + // Parenthesize a `new` if there is one + if (path.indexOf("new ") === 0) { + path = `(${path})`; + } + const str = "" + args[0]; + // If leading, just print back the arg (irrespective of if it's a valid identifier) + if (path.length === 0) { + path = `${str}`; + } + // Otherwise write a dotted name if possible + else if (isIdentifierText(str, getEmitScriptTarget(compilerOptions))) { + path = `${path}.${str}`; + } + // Failing that, check if the name is already a computed name + else if (str[0] === "[" && str[str.length - 1] === "]") { + path = `${path}${str}`; + } + // And finally write out a computed name as a last resort + else { + path = `${path}[${str}]`; + } + break; + } + case Diagnostics.Call_signature_return_types_0_and_1_are_incompatible.code: + case Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code: + case Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code: + case Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code: { + if (path.length === 0) { + // Don't flatten signature compatability errors at the start of a chain - instead prefer + // to unify (the with no arguments bit is excessive for printback) and print them back + let mappedMsg = msg; + if (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) { + mappedMsg = Diagnostics.Call_signature_return_types_0_and_1_are_incompatible; + } + else if (msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) { + mappedMsg = Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible; + } + secondaryRootErrors.unshift([mappedMsg, args[0], args[1]]); + } + else { + const prefix = (msg.code === Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code || + msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) + ? "new " + : ""; + const params = (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code || + msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) + ? "" + : "..."; + path = `${prefix}${path}(${params})`; + } + break; + } + case Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target.code: { + secondaryRootErrors.unshift([Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target, args[0], args[1]]); + break; + } + case Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target.code: { + secondaryRootErrors.unshift([Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target, args[0], args[1], args[2]]); + break; + } + default: + return Debug.fail(`Unhandled Diagnostic: ${msg.code}`); + } + } + if (path) { + reportError( + path[path.length - 1] === ")" + ? Diagnostics.The_types_returned_by_0_are_incompatible_between_these_types + : Diagnostics.The_types_of_0_are_incompatible_between_these_types, + path, + ); + } + else { + // Remove the innermost secondary error as it will duplicate the error already reported by `reportRelationError` on entry + secondaryRootErrors.shift(); + } + for (const [msg, ...args] of secondaryRootErrors) { + const originalValue = msg.elidedInCompatabilityPyramid; + msg.elidedInCompatabilityPyramid = false; // Temporarily override elision to ensure error is reported + reportError(msg, ...args); + msg.elidedInCompatabilityPyramid = originalValue; + } + if (info) { + // Actually do the last relation error + reportRelationError(/*message*/ undefined, ...info); + } + } + + function reportError(message: DiagnosticMessage, ...args: DiagnosticArguments): void { + Debug.assert(!!errorNode); + if (incompatibleStack) reportIncompatibleStack(); + if (message.elidedInCompatabilityPyramid) return; + if (skipParentCounter === 0) { + errorInfo = chainDiagnosticMessages(errorInfo, message, ...args); + } + else { + skipParentCounter--; + } + } + + function reportParentSkippedError(message: DiagnosticMessage, ...args: DiagnosticArguments): void { + reportError(message, ...args); + skipParentCounter++; + } + + function associateRelatedInfo(info: DiagnosticRelatedInformation) { + Debug.assert(!!errorInfo); + if (!relatedInfo) { + relatedInfo = [info]; + } + else { + relatedInfo.push(info); + } + } + + function reportRelationError(message: DiagnosticMessage | undefined, source: Type, target: Type) { + if (incompatibleStack) reportIncompatibleStack(); + const [sourceType, targetType] = getTypeNamesForErrorDisplay(source, target); + let generalizedSource = source; + let generalizedSourceType = sourceType; + + if (isLiteralType(source) && !typeCouldHaveTopLevelSingletonTypes(target)) { + generalizedSource = getBaseTypeOfLiteralType(source); + Debug.assert(!isTypeAssignableTo(generalizedSource, target), "generalized source shouldn't be assignable"); + generalizedSourceType = getTypeNameForErrorDisplay(generalizedSource); + } + + // If `target` is of indexed access type (And `source` it is not), we use the object type of `target` for better error reporting + const targetFlags = target.flags & TypeFlags.IndexedAccess && !(source.flags & TypeFlags.IndexedAccess) ? + (target as IndexedAccessType).objectType.flags : + target.flags; + + if (targetFlags & TypeFlags.TypeParameter && target !== markerSuperTypeForCheck && target !== markerSubTypeForCheck) { + const constraint = getBaseConstraintOfType(target); + let needsOriginalSource; + if (constraint && (isTypeAssignableTo(generalizedSource, constraint) || (needsOriginalSource = isTypeAssignableTo(source, constraint)))) { + reportError( + Diagnostics._0_is_assignable_to_the_constraint_of_type_1_but_1_could_be_instantiated_with_a_different_subtype_of_constraint_2, + needsOriginalSource ? sourceType : generalizedSourceType, + targetType, + typeToString(constraint), + ); + } + else { + errorInfo = undefined; + reportError( + Diagnostics._0_could_be_instantiated_with_an_arbitrary_type_which_could_be_unrelated_to_1, + targetType, + generalizedSourceType, + ); + } + } + + if (!message) { + if (relation === comparableRelation) { + message = Diagnostics.Type_0_is_not_comparable_to_type_1; + } + else if (sourceType === targetType) { + message = Diagnostics.Type_0_is_not_assignable_to_type_1_Two_different_types_with_this_name_exist_but_they_are_unrelated; + } + else if (exactOptionalPropertyTypes && getExactOptionalUnassignableProperties(source, target).length) { + message = Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties; + } + else { + if (source.flags & TypeFlags.StringLiteral && target.flags & TypeFlags.Union) { + const suggestedType = getSuggestedTypeForNonexistentStringLiteralType(source as StringLiteralType, target as UnionType); + if (suggestedType) { + reportError(Diagnostics.Type_0_is_not_assignable_to_type_1_Did_you_mean_2, generalizedSourceType, targetType, typeToString(suggestedType)); + return; + } + } + message = Diagnostics.Type_0_is_not_assignable_to_type_1; + } + } + else if ( + message === Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1 + && exactOptionalPropertyTypes + && getExactOptionalUnassignableProperties(source, target).length + ) { + message = Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties; + } + + reportError(message, generalizedSourceType, targetType); + } + + function tryElaborateErrorsForPrimitivesAndObjects(source: Type, target: Type) { + const sourceType = symbolValueDeclarationIsContextSensitive(source.symbol) ? typeToString(source, source.symbol.valueDeclaration) : typeToString(source); + const targetType = symbolValueDeclarationIsContextSensitive(target.symbol) ? typeToString(target, target.symbol.valueDeclaration) : typeToString(target); + + if ( + (globalStringType === source && stringType === target) || + (globalNumberType === source && numberType === target) || + (globalBooleanType === source && booleanType === target) || + (getGlobalESSymbolType() === source && esSymbolType === target) + ) { + reportError(Diagnostics._0_is_a_primitive_but_1_is_a_wrapper_object_Prefer_using_0_when_possible, targetType, sourceType); + } + } + + /** + * Try and elaborate array and tuple errors. Returns false + * if we have found an elaboration, or we should ignore + * any other elaborations when relating the `source` and + * `target` types. + */ + function tryElaborateArrayLikeErrors(source: Type, target: Type, reportErrors: boolean): boolean { + /** + * The spec for elaboration is: + * - If the source is a readonly tuple and the target is a mutable array or tuple, elaborate on mutability and skip property elaborations. + * - If the source is a tuple then skip property elaborations if the target is an array or tuple. + * - If the source is a readonly array and the target is a mutable array or tuple, elaborate on mutability and skip property elaborations. + * - If the source an array then skip property elaborations if the target is a tuple. + */ + if (isTupleType(source)) { + if (source.target.readonly && isMutableArrayOrTuple(target)) { + if (reportErrors) { + reportError(Diagnostics.The_type_0_is_readonly_and_cannot_be_assigned_to_the_mutable_type_1, typeToString(source), typeToString(target)); + } + return false; + } + return isArrayOrTupleType(target); + } + if (isReadonlyArrayType(source) && isMutableArrayOrTuple(target)) { + if (reportErrors) { + reportError(Diagnostics.The_type_0_is_readonly_and_cannot_be_assigned_to_the_mutable_type_1, typeToString(source), typeToString(target)); + } + return false; + } + if (isTupleType(target)) { + return isArrayType(source); + } + return true; + } + + function isRelatedToWorker(source: Type, target: Type, reportErrors?: boolean) { + return isRelatedTo(source, target, RecursionFlags.Both, reportErrors); + } + + /** + * Compare two types and return + * * Ternary.True if they are related with no assumptions, + * * Ternary.Maybe if they are related with assumptions of other relationships, or + * * Ternary.False if they are not related. + */ + function isRelatedTo(originalSource: Type, originalTarget: Type, recursionFlags: RecursionFlags = RecursionFlags.Both, reportErrors = false, headMessage?: DiagnosticMessage, intersectionState = IntersectionState.None): Ternary { + if (originalSource === originalTarget) return Ternary.True; + + // Before normalization: if `source` is type an object type, and `target` is primitive, + // skip all the checks we don't need and just return `isSimpleTypeRelatedTo` result + if (originalSource.flags & TypeFlags.Object && originalTarget.flags & TypeFlags.Primitive) { + if ( + relation === comparableRelation && !(originalTarget.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(originalTarget, originalSource, relation) || + isSimpleTypeRelatedTo(originalSource, originalTarget, relation, reportErrors ? reportError : undefined) + ) { + return Ternary.True; + } + if (reportErrors) { + reportErrorResults(originalSource, originalTarget, originalSource, originalTarget, headMessage); + } + return Ternary.False; + } + + // Normalize the source and target types: Turn fresh literal types into regular literal types, + // turn deferred type references into regular type references, simplify indexed access and + // conditional types, and resolve substitution types to either the substitution (on the source + // side) or the type variable (on the target side). + const source = getNormalizedType(originalSource, /*writing*/ false); + let target = getNormalizedType(originalTarget, /*writing*/ true); + + if (source === target) return Ternary.True; + + if (relation === identityRelation) { + if (source.flags !== target.flags) return Ternary.False; + if (source.flags & TypeFlags.Singleton) return Ternary.True; + traceUnionsOrIntersectionsTooLarge(source, target); + return recursiveTypeRelatedTo(source, target, /*reportErrors*/ false, IntersectionState.None, recursionFlags); + } + + // We fastpath comparing a type parameter to exactly its constraint, as this is _super_ common, + // and otherwise, for type parameters in large unions, causes us to need to compare the union to itself, + // as we break down the _target_ union first, _then_ get the source constraint - so for every + // member of the target, we attempt to find a match in the source. This avoids that in cases where + // the target is exactly the constraint. + if (source.flags & TypeFlags.TypeParameter && getConstraintOfType(source) === target) { + return Ternary.True; + } + + // See if we're relating a definitely non-nullable type to a union that includes null and/or undefined + // plus a single non-nullable type. If so, remove null and/or undefined from the target type. + if (source.flags & TypeFlags.DefinitelyNonNullable && target.flags & TypeFlags.Union) { + const types = (target as UnionType).types; + const candidate = types.length === 2 && types[0].flags & TypeFlags.Nullable ? types[1] : + types.length === 3 && types[0].flags & TypeFlags.Nullable && types[1].flags & TypeFlags.Nullable ? types[2] : + undefined; + if (candidate && !(candidate.flags & TypeFlags.Nullable)) { + target = getNormalizedType(candidate, /*writing*/ true); + if (source === target) return Ternary.True; + } + } + + if ( + relation === comparableRelation && !(target.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(target, source, relation) || + isSimpleTypeRelatedTo(source, target, relation, reportErrors ? reportError : undefined) + ) return Ternary.True; + + if (source.flags & TypeFlags.StructuredOrInstantiable || target.flags & TypeFlags.StructuredOrInstantiable) { + const isPerformingExcessPropertyChecks = !(intersectionState & IntersectionState.Target) && (isObjectLiteralType(source) && getObjectFlags(source) & ObjectFlags.FreshLiteral); + if (isPerformingExcessPropertyChecks) { + if (hasExcessProperties(source as FreshObjectLiteralType, target, reportErrors)) { + if (reportErrors) { + reportRelationError(headMessage, source, originalTarget.aliasSymbol ? originalTarget : target); + } + return Ternary.False; + } + } + + const isPerformingCommonPropertyChecks = (relation !== comparableRelation || isUnitType(source)) && + !(intersectionState & IntersectionState.Target) && + source.flags & (TypeFlags.Primitive | TypeFlags.Object | TypeFlags.Intersection) && source !== globalObjectType && + target.flags & (TypeFlags.Object | TypeFlags.Intersection) && isWeakType(target) && + (getPropertiesOfType(source).length > 0 || typeHasCallOrConstructSignatures(source)); + const isComparingJsxAttributes = !!(getObjectFlags(source) & ObjectFlags.JsxAttributes); + if (isPerformingCommonPropertyChecks && !hasCommonProperties(source, target, isComparingJsxAttributes)) { + if (reportErrors) { + const sourceString = typeToString(originalSource.aliasSymbol ? originalSource : source); + const targetString = typeToString(originalTarget.aliasSymbol ? originalTarget : target); + const calls = getSignaturesOfType(source, SignatureKind.Call); + const constructs = getSignaturesOfType(source, SignatureKind.Construct); + if ( + calls.length > 0 && isRelatedTo(getReturnTypeOfSignature(calls[0]), target, RecursionFlags.Source, /*reportErrors*/ false) || + constructs.length > 0 && isRelatedTo(getReturnTypeOfSignature(constructs[0]), target, RecursionFlags.Source, /*reportErrors*/ false) + ) { + reportError(Diagnostics.Value_of_type_0_has_no_properties_in_common_with_type_1_Did_you_mean_to_call_it, sourceString, targetString); + } + else { + reportError(Diagnostics.Type_0_has_no_properties_in_common_with_type_1, sourceString, targetString); + } + } + return Ternary.False; + } + + traceUnionsOrIntersectionsTooLarge(source, target); + + const skipCaching = source.flags & TypeFlags.Union && (source as UnionType).types.length < 4 && !(target.flags & TypeFlags.Union) || + target.flags & TypeFlags.Union && (target as UnionType).types.length < 4 && !(source.flags & TypeFlags.StructuredOrInstantiable); + const result = skipCaching ? + unionOrIntersectionRelatedTo(source, target, reportErrors, intersectionState) : + recursiveTypeRelatedTo(source, target, reportErrors, intersectionState, recursionFlags); + if (result) { + return result; + } + } + + if (reportErrors) { + reportErrorResults(originalSource, originalTarget, source, target, headMessage); + } + return Ternary.False; + } + + function reportErrorResults(originalSource: Type, originalTarget: Type, source: Type, target: Type, headMessage: DiagnosticMessage | undefined) { + const sourceHasBase = !!getSingleBaseForNonAugmentingSubtype(originalSource); + const targetHasBase = !!getSingleBaseForNonAugmentingSubtype(originalTarget); + source = (originalSource.aliasSymbol || sourceHasBase) ? originalSource : source; + target = (originalTarget.aliasSymbol || targetHasBase) ? originalTarget : target; + let maybeSuppress = overrideNextErrorInfo > 0; + if (maybeSuppress) { + overrideNextErrorInfo--; + } + if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) { + const currentError = errorInfo; + tryElaborateArrayLikeErrors(source, target, /*reportErrors*/ true); + if (errorInfo !== currentError) { + maybeSuppress = !!errorInfo; + } + } + if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Primitive) { + tryElaborateErrorsForPrimitivesAndObjects(source, target); + } + else if (source.symbol && source.flags & TypeFlags.Object && globalObjectType === source) { + reportError(Diagnostics.The_Object_type_is_assignable_to_very_few_other_types_Did_you_mean_to_use_the_any_type_instead); + } + else if (getObjectFlags(source) & ObjectFlags.JsxAttributes && target.flags & TypeFlags.Intersection) { + const targetTypes = (target as IntersectionType).types; + const intrinsicAttributes = getJsxType(JsxNames.IntrinsicAttributes, errorNode); + const intrinsicClassAttributes = getJsxType(JsxNames.IntrinsicClassAttributes, errorNode); + if ( + !isErrorType(intrinsicAttributes) && !isErrorType(intrinsicClassAttributes) && + (contains(targetTypes, intrinsicAttributes) || contains(targetTypes, intrinsicClassAttributes)) + ) { + // do not report top error + return; + } + } + else { + errorInfo = elaborateNeverIntersection(errorInfo, originalTarget); + } + // Used by, eg, missing property checking to replace the top-level message with a more informative one. + if (!headMessage && maybeSuppress) { + // We suppress a call to `reportRelationError` or not depending on the state of the type checker, so + // we call `reportRelationError` here and then undo its effects to figure out what would be the diagnostic + // if we hadn't supress it, and save that as a canonical diagnostic for deduplication purposes. + const savedErrorState = captureErrorCalculationState(); + reportRelationError(headMessage, source, target); + let canonical; + if (errorInfo && errorInfo !== savedErrorState.errorInfo) { + canonical = { code: errorInfo.code, messageText: errorInfo.messageText }; + } + resetErrorInfo(savedErrorState); + if (canonical && errorInfo) { + errorInfo.canonicalHead = canonical; + } + + lastSkippedInfo = [source, target]; + return; + } + reportRelationError(headMessage, source, target); + if (source.flags & TypeFlags.TypeParameter && source.symbol?.declarations?.[0] && !getConstraintOfType(source as TypeVariable)) { + const syntheticParam = cloneTypeParameter(source as TypeParameter); + syntheticParam.constraint = instantiateType(target, makeUnaryTypeMapper(source, syntheticParam)); + if (hasNonCircularBaseConstraint(syntheticParam)) { + const targetConstraintString = typeToString(target, source.symbol.declarations[0]); + associateRelatedInfo(createDiagnosticForNode(source.symbol.declarations[0], Diagnostics.This_type_parameter_might_need_an_extends_0_constraint, targetConstraintString)); + } + } + } + + function traceUnionsOrIntersectionsTooLarge(source: Type, target: Type): void { + if (!tracing) { + return; + } + + if ((source.flags & TypeFlags.UnionOrIntersection) && (target.flags & TypeFlags.UnionOrIntersection)) { + const sourceUnionOrIntersection = source as UnionOrIntersectionType; + const targetUnionOrIntersection = target as UnionOrIntersectionType; + + if (sourceUnionOrIntersection.objectFlags & targetUnionOrIntersection.objectFlags & ObjectFlags.PrimitiveUnion) { + // There's a fast path for comparing primitive unions + return; + } + + const sourceSize = sourceUnionOrIntersection.types.length; + const targetSize = targetUnionOrIntersection.types.length; + if (sourceSize * targetSize > 1E6) { + tracing.instant(tracing.Phase.CheckTypes, "traceUnionsOrIntersectionsTooLarge_DepthLimit", { + sourceId: source.id, + sourceSize, + targetId: target.id, + targetSize, + pos: errorNode?.pos, + end: errorNode?.end, + }); + } + } + } + + function getTypeOfPropertyInTypes(types: Type[], name: __String) { + const appendPropType = (propTypes: Type[] | undefined, type: Type) => { + type = getApparentType(type); + const prop = type.flags & TypeFlags.UnionOrIntersection ? getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name) : getPropertyOfObjectType(type, name); + const propType = prop && getTypeOfSymbol(prop) || getApplicableIndexInfoForName(type, name)?.type || undefinedType; + return append(propTypes, propType); + }; + return getUnionType(reduceLeft(types, appendPropType, /*initial*/ undefined) || emptyArray); + } + + function hasExcessProperties(source: FreshObjectLiteralType, target: Type, reportErrors: boolean): boolean { + if (!isExcessPropertyCheckTarget(target) || !noImplicitAny && getObjectFlags(target) & ObjectFlags.JSLiteral) { + return false; // Disable excess property checks on JS literals to simulate having an implicit "index signature" - but only outside of noImplicitAny + } + const isComparingJsxAttributes = !!(getObjectFlags(source) & ObjectFlags.JsxAttributes); + if ( + (relation === assignableRelation || relation === comparableRelation) && + (isTypeSubsetOf(globalObjectType, target) || (!isComparingJsxAttributes && isEmptyObjectType(target))) + ) { + return false; + } + let reducedTarget = target; + let checkTypes: Type[] | undefined; + if (target.flags & TypeFlags.Union) { + reducedTarget = findMatchingDiscriminantType(source, target as UnionType, isRelatedTo) || filterPrimitivesIfContainsNonPrimitive(target as UnionType); + checkTypes = reducedTarget.flags & TypeFlags.Union ? (reducedTarget as UnionType).types : [reducedTarget]; + } + for (const prop of getPropertiesOfType(source)) { + if (shouldCheckAsExcessProperty(prop, source.symbol) && !isIgnoredJsxProperty(source, prop)) { + if (!isKnownProperty(reducedTarget, prop.escapedName, isComparingJsxAttributes)) { + if (reportErrors) { + // Report error in terms of object types in the target as those are the only ones + // we check in isKnownProperty. + const errorTarget = filterType(reducedTarget, isExcessPropertyCheckTarget); + // We know *exactly* where things went wrong when comparing the types. + // Use this property as the error node as this will be more helpful in + // reasoning about what went wrong. + if (!errorNode) return Debug.fail(); + if (isJsxAttributes(errorNode) || isJsxOpeningLikeElement(errorNode) || isJsxOpeningLikeElement(errorNode.parent)) { + // JsxAttributes has an object-literal flag and undergo same type-assignablity check as normal object-literal. + // However, using an object-literal error message will be very confusing to the users so we give different a message. + if (prop.valueDeclaration && isJsxAttribute(prop.valueDeclaration) && getSourceFileOfNode(errorNode) === getSourceFileOfNode(prop.valueDeclaration.name)) { + // Note that extraneous children (as in `extra`) don't pass this check, + // since `children` is a SyntaxKind.PropertySignature instead of a SyntaxKind.JsxAttribute. + errorNode = prop.valueDeclaration.name; + } + const propName = symbolToString(prop); + const suggestionSymbol = getSuggestedSymbolForNonexistentJSXAttribute(propName, errorTarget); + const suggestion = suggestionSymbol ? symbolToString(suggestionSymbol) : undefined; + if (suggestion) { + reportError(Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2, propName, typeToString(errorTarget), suggestion); + } + else { + reportError(Diagnostics.Property_0_does_not_exist_on_type_1, propName, typeToString(errorTarget)); + } + } + else { + // use the property's value declaration if the property is assigned inside the literal itself + const objectLiteralDeclaration = source.symbol?.declarations && firstOrUndefined(source.symbol.declarations); + let suggestion: string | undefined; + if (prop.valueDeclaration && findAncestor(prop.valueDeclaration, d => d === objectLiteralDeclaration) && getSourceFileOfNode(objectLiteralDeclaration) === getSourceFileOfNode(errorNode)) { + const propDeclaration = prop.valueDeclaration as ObjectLiteralElementLike; + Debug.assertNode(propDeclaration, isObjectLiteralElementLike); + + const name = propDeclaration.name!; + errorNode = name; + + if (isIdentifier(name)) { + suggestion = getSuggestionForNonexistentProperty(name, errorTarget); + } + } + if (suggestion !== undefined) { + reportParentSkippedError(Diagnostics.Object_literal_may_only_specify_known_properties_but_0_does_not_exist_in_type_1_Did_you_mean_to_write_2, symbolToString(prop), typeToString(errorTarget), suggestion); + } + else { + reportParentSkippedError(Diagnostics.Object_literal_may_only_specify_known_properties_and_0_does_not_exist_in_type_1, symbolToString(prop), typeToString(errorTarget)); + } + } + } + return true; + } + if (checkTypes && !isRelatedTo(getTypeOfSymbol(prop), getTypeOfPropertyInTypes(checkTypes, prop.escapedName), RecursionFlags.Both, reportErrors)) { + if (reportErrors) { + reportIncompatibleError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(prop)); + } + return true; + } + } + } + return false; + } + + function shouldCheckAsExcessProperty(prop: Symbol, container: Symbol) { + return prop.valueDeclaration && container.valueDeclaration && prop.valueDeclaration.parent === container.valueDeclaration; + } + + function unionOrIntersectionRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + // Note that these checks are specifically ordered to produce correct results. In particular, + // we need to deconstruct unions before intersections (because unions are always at the top), + // and we need to handle "each" relations before "some" relations for the same kind of type. + if (source.flags & TypeFlags.Union) { + if (target.flags & TypeFlags.Union) { + // Intersections of union types are normalized into unions of intersection types, and such normalized + // unions can get very large and expensive to relate. The following fast path checks if the source union + // originated in an intersection. If so, and if that intersection contains the target type, then we know + // the result to be true (for any two types A and B, A & B is related to both A and B). + const sourceOrigin = (source as UnionType).origin; + if (sourceOrigin && sourceOrigin.flags & TypeFlags.Intersection && target.aliasSymbol && contains((sourceOrigin as IntersectionType).types, target)) { + return Ternary.True; + } + // Similarly, in unions of unions the we preserve the original list of unions. This original list is often + // much shorter than the normalized result, so we scan it in the following fast path. + const targetOrigin = (target as UnionType).origin; + if (targetOrigin && targetOrigin.flags & TypeFlags.Union && source.aliasSymbol && contains((targetOrigin as UnionType).types, source)) { + return Ternary.True; + } + } + return relation === comparableRelation ? + someTypeRelatedToType(source as UnionType, target, reportErrors && !(source.flags & TypeFlags.Primitive), intersectionState) : + eachTypeRelatedToType(source as UnionType, target, reportErrors && !(source.flags & TypeFlags.Primitive), intersectionState); + } + if (target.flags & TypeFlags.Union) { + return typeRelatedToSomeType(getRegularTypeOfObjectLiteral(source), target as UnionType, reportErrors && !(source.flags & TypeFlags.Primitive) && !(target.flags & TypeFlags.Primitive), intersectionState); + } + if (target.flags & TypeFlags.Intersection) { + return typeRelatedToEachType(source, target as IntersectionType, reportErrors, IntersectionState.Target); + } + // Source is an intersection. For the comparable relation, if the target is a primitive type we hoist the + // constraints of all non-primitive types in the source into a new intersection. We do this because the + // intersection may further constrain the constraints of the non-primitive types. For example, given a type + // parameter 'T extends 1 | 2', the intersection 'T & 1' should be reduced to '1' such that it doesn't + // appear to be comparable to '2'. + if (relation === comparableRelation && target.flags & TypeFlags.Primitive) { + const constraints = sameMap((source as IntersectionType).types, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOfType(t) || unknownType : t); + if (constraints !== (source as IntersectionType).types) { + source = getIntersectionType(constraints); + if (source.flags & TypeFlags.Never) { + return Ternary.False; + } + if (!(source.flags & TypeFlags.Intersection)) { + return isRelatedTo(source, target, RecursionFlags.Source, /*reportErrors*/ false) || + isRelatedTo(target, source, RecursionFlags.Source, /*reportErrors*/ false); + } + } + } + // Check to see if any constituents of the intersection are immediately related to the target. + // Don't report errors though. Elaborating on whether a source constituent is related to the target is + // not actually useful and leads to some confusing error messages. Instead, we rely on the caller + // checking whether the full intersection viewed as an object is related to the target. + return someTypeRelatedToType(source as IntersectionType, target, /*reportErrors*/ false, IntersectionState.Source); + } + + function eachTypeRelatedToSomeType(source: UnionOrIntersectionType, target: UnionOrIntersectionType): Ternary { + let result = Ternary.True; + const sourceTypes = source.types; + for (const sourceType of sourceTypes) { + const related = typeRelatedToSomeType(sourceType, target, /*reportErrors*/ false, IntersectionState.None); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function typeRelatedToSomeType(source: Type, target: UnionOrIntersectionType, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const targetTypes = target.types; + if (target.flags & TypeFlags.Union) { + if (containsType(targetTypes, source)) { + return Ternary.True; + } + if ( + relation !== comparableRelation && getObjectFlags(target) & ObjectFlags.PrimitiveUnion && !(source.flags & TypeFlags.EnumLiteral) && ( + source.flags & (TypeFlags.StringLiteral | TypeFlags.BooleanLiteral | TypeFlags.BigIntLiteral) || + (relation === subtypeRelation || relation === strictSubtypeRelation) && source.flags & TypeFlags.NumberLiteral + ) + ) { + // When relating a literal type to a union of primitive types, we know the relation is false unless + // the union contains the base primitive type or the literal type in one of its fresh/regular forms. + // We exclude numeric literals for non-subtype relations because numeric literals are assignable to + // numeric enum literals with the same value. Similarly, we exclude enum literal types because + // identically named enum types are related (see isEnumTypeRelatedTo). We exclude the comparable + // relation in entirety because it needs to be checked in both directions. + const alternateForm = source === (source as StringLiteralType).regularType ? (source as StringLiteralType).freshType : (source as StringLiteralType).regularType; + const primitive = source.flags & TypeFlags.StringLiteral ? stringType : + source.flags & TypeFlags.NumberLiteral ? numberType : + source.flags & TypeFlags.BigIntLiteral ? bigintType : + undefined; + return primitive && containsType(targetTypes, primitive) || alternateForm && containsType(targetTypes, alternateForm) ? Ternary.True : Ternary.False; + } + const match = getMatchingUnionConstituentForType(target as UnionType, source); + if (match) { + const related = isRelatedTo(source, match, RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (related) { + return related; + } + } + } + for (const type of targetTypes) { + const related = isRelatedTo(source, type, RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (related) { + return related; + } + } + if (reportErrors) { + // Elaborate only if we can find a best matching type in the target union + const bestMatchingType = getBestMatchingType(source, target, isRelatedTo); + if (bestMatchingType) { + isRelatedTo(source, bestMatchingType, RecursionFlags.Target, /*reportErrors*/ true, /*headMessage*/ undefined, intersectionState); + } + } + return Ternary.False; + } + + function typeRelatedToEachType(source: Type, target: IntersectionType, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + let result = Ternary.True; + const targetTypes = target.types; + for (const targetType of targetTypes) { + const related = isRelatedTo(source, targetType, RecursionFlags.Target, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function someTypeRelatedToType(source: UnionOrIntersectionType, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const sourceTypes = source.types; + if (source.flags & TypeFlags.Union && containsType(sourceTypes, target)) { + return Ternary.True; + } + const len = sourceTypes.length; + for (let i = 0; i < len; i++) { + const related = isRelatedTo(sourceTypes[i], target, RecursionFlags.Source, reportErrors && i === len - 1, /*headMessage*/ undefined, intersectionState); + if (related) { + return related; + } + } + return Ternary.False; + } + + function getUndefinedStrippedTargetIfNeeded(source: Type, target: Type) { + if ( + source.flags & TypeFlags.Union && target.flags & TypeFlags.Union && + !((source as UnionType).types[0].flags & TypeFlags.Undefined) && (target as UnionType).types[0].flags & TypeFlags.Undefined + ) { + return extractTypesOfKind(target, ~TypeFlags.Undefined); + } + return target; + } + + function eachTypeRelatedToType(source: UnionOrIntersectionType, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + let result = Ternary.True; + const sourceTypes = source.types; + // We strip `undefined` from the target if the `source` trivially doesn't contain it for our correspondence-checking fastpath + // since `undefined` is frequently added by optionality and would otherwise spoil a potentially useful correspondence + const undefinedStrippedTarget = getUndefinedStrippedTargetIfNeeded(source, target as UnionType); + for (let i = 0; i < sourceTypes.length; i++) { + const sourceType = sourceTypes[i]; + if (undefinedStrippedTarget.flags & TypeFlags.Union && sourceTypes.length >= (undefinedStrippedTarget as UnionType).types.length && sourceTypes.length % (undefinedStrippedTarget as UnionType).types.length === 0) { + // many unions are mappings of one another; in such cases, simply comparing members at the same index can shortcut the comparison + // such unions will have identical lengths, and their corresponding elements will match up. Another common scenario is where a large + // union has a union of objects intersected with it. In such cases, if the input was, eg `("a" | "b" | "c") & (string | boolean | {} | {whatever})`, + // the result will have the structure `"a" | "b" | "c" | "a" & {} | "b" & {} | "c" & {} | "a" & {whatever} | "b" & {whatever} | "c" & {whatever}` + // - the resulting union has a length which is a multiple of the original union, and the elements correspond modulo the length of the original union + const related = isRelatedTo(sourceType, (undefinedStrippedTarget as UnionType).types[i % (undefinedStrippedTarget as UnionType).types.length], RecursionFlags.Both, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (related) { + result &= related; + continue; + } + } + const related = isRelatedTo(sourceType, target, RecursionFlags.Source, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function typeArgumentsRelatedTo(sources: readonly Type[] = emptyArray, targets: readonly Type[] = emptyArray, variances: readonly VarianceFlags[] = emptyArray, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + if (sources.length !== targets.length && relation === identityRelation) { + return Ternary.False; + } + const length = sources.length <= targets.length ? sources.length : targets.length; + let result = Ternary.True; + for (let i = 0; i < length; i++) { + // When variance information isn't available we default to covariance. This happens + // in the process of computing variance information for recursive types and when + // comparing 'this' type arguments. + const varianceFlags = i < variances.length ? variances[i] : VarianceFlags.Covariant; + const variance = varianceFlags & VarianceFlags.VarianceMask; + // We ignore arguments for independent type parameters (because they're never witnessed). + if (variance !== VarianceFlags.Independent) { + const s = sources[i]; + const t = targets[i]; + let related = Ternary.True; + if (varianceFlags & VarianceFlags.Unmeasurable) { + // Even an `Unmeasurable` variance works out without a structural check if the source and target are _identical_. + // We can't simply assume invariance, because `Unmeasurable` marks nonlinear relations, for example, a relation tained by + // the `-?` modifier in a mapped type (where, no matter how the inputs are related, the outputs still might not be) + related = relation === identityRelation ? isRelatedTo(s, t, RecursionFlags.Both, /*reportErrors*/ false) : compareTypesIdentical(s, t); + } + else if (variance === VarianceFlags.Covariant) { + related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + else if (variance === VarianceFlags.Contravariant) { + related = isRelatedTo(t, s, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + else if (variance === VarianceFlags.Bivariant) { + // In the bivariant case we first compare contravariantly without reporting + // errors. Then, if that doesn't succeed, we compare covariantly with error + // reporting. Thus, error elaboration will be based on the the covariant check, + // which is generally easier to reason about. + related = isRelatedTo(t, s, RecursionFlags.Both, /*reportErrors*/ false); + if (!related) { + related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + } + else { + // In the invariant case we first compare covariantly, and only when that + // succeeds do we proceed to compare contravariantly. Thus, error elaboration + // will typically be based on the covariant check. + related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (related) { + related &= isRelatedTo(t, s, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + } + if (!related) { + return Ternary.False; + } + result &= related; + } + } + return result; + } + + // Determine if possibly recursive types are related. First, check if the result is already available in the global cache. + // Second, check if we have already started a comparison of the given two types in which case we assume the result to be true. + // Third, check if both types are part of deeply nested chains of generic type instantiations and if so assume the types are + // equal and infinitely expanding. Fourth, if we have reached a depth of 100 nested comparisons, assume we have runaway recursion + // and issue an error. Otherwise, actually compare the structure of the two types. + function recursiveTypeRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState, recursionFlags: RecursionFlags): Ternary { + if (overflow) { + return Ternary.False; + } + const id = getRelationKey(source, target, intersectionState, relation, /*ignoreConstraints*/ false); + const entry = relation.get(id); + if (entry !== undefined) { + if (reportErrors && entry & RelationComparisonResult.Failed && !(entry & RelationComparisonResult.Reported)) { + // We are elaborating errors and the cached result is an unreported failure. The result will be reported + // as a failure, and should be updated as a reported failure by the bottom of this function. + } + else { + if (outofbandVarianceMarkerHandler) { + // We're in the middle of variance checking - integrate any unmeasurable/unreliable flags from this cached component + const saved = entry & RelationComparisonResult.ReportsMask; + if (saved & RelationComparisonResult.ReportsUnmeasurable) { + instantiateType(source, reportUnmeasurableMapper); + } + if (saved & RelationComparisonResult.ReportsUnreliable) { + instantiateType(source, reportUnreliableMapper); + } + } + return entry & RelationComparisonResult.Succeeded ? Ternary.True : Ternary.False; + } + } + if (relationCount <= 0) { + overflow = true; + return Ternary.False; + } + if (!maybeKeys) { + maybeKeys = []; + maybeKeysSet = new Set(); + sourceStack = []; + targetStack = []; + } + else { + // If source and target are already being compared, consider them related with assumptions + if (maybeKeysSet.has(id)) { + return Ternary.Maybe; + } + + // A key that starts with "*" is an indication that we have type references that reference constrained + // type parameters. For such keys we also check against the key we would have gotten if all type parameters + // were unconstrained. + const broadestEquivalentId = id.startsWith("*") ? getRelationKey(source, target, intersectionState, relation, /*ignoreConstraints*/ true) : undefined; + if (broadestEquivalentId && maybeKeysSet.has(broadestEquivalentId)) { + return Ternary.Maybe; + } + + if (sourceDepth === 100 || targetDepth === 100) { + overflow = true; + return Ternary.False; + } + } + const maybeStart = maybeCount; + maybeKeys[maybeCount] = id; + maybeKeysSet.add(id); + maybeCount++; + const saveExpandingFlags = expandingFlags; + if (recursionFlags & RecursionFlags.Source) { + sourceStack[sourceDepth] = source; + sourceDepth++; + if (!(expandingFlags & ExpandingFlags.Source) && isDeeplyNestedType(source, sourceStack, sourceDepth)) expandingFlags |= ExpandingFlags.Source; + } + if (recursionFlags & RecursionFlags.Target) { + targetStack[targetDepth] = target; + targetDepth++; + if (!(expandingFlags & ExpandingFlags.Target) && isDeeplyNestedType(target, targetStack, targetDepth)) expandingFlags |= ExpandingFlags.Target; + } + let originalHandler: typeof outofbandVarianceMarkerHandler; + let propagatingVarianceFlags = 0 as RelationComparisonResult; + if (outofbandVarianceMarkerHandler) { + originalHandler = outofbandVarianceMarkerHandler; + outofbandVarianceMarkerHandler = onlyUnreliable => { + propagatingVarianceFlags |= onlyUnreliable ? RelationComparisonResult.ReportsUnreliable : RelationComparisonResult.ReportsUnmeasurable; + return originalHandler!(onlyUnreliable); + }; + } + + let result: Ternary; + if (expandingFlags === ExpandingFlags.Both) { + tracing?.instant(tracing.Phase.CheckTypes, "recursiveTypeRelatedTo_DepthLimit", { + sourceId: source.id, + sourceIdStack: sourceStack.map(t => t.id), + targetId: target.id, + targetIdStack: targetStack.map(t => t.id), + depth: sourceDepth, + targetDepth, + }); + result = Ternary.Maybe; + } + else { + tracing?.push(tracing.Phase.CheckTypes, "structuredTypeRelatedTo", { sourceId: source.id, targetId: target.id }); + result = structuredTypeRelatedTo(source, target, reportErrors, intersectionState); + tracing?.pop(); + } + + if (outofbandVarianceMarkerHandler) { + outofbandVarianceMarkerHandler = originalHandler; + } + if (recursionFlags & RecursionFlags.Source) { + sourceDepth--; + } + if (recursionFlags & RecursionFlags.Target) { + targetDepth--; + } + expandingFlags = saveExpandingFlags; + if (result) { + if (result === Ternary.True || (sourceDepth === 0 && targetDepth === 0)) { + if (result === Ternary.True || result === Ternary.Maybe) { + // If result is definitely true, record all maybe keys as having succeeded. Also, record Ternary.Maybe + // results as having succeeded once we reach depth 0, but never record Ternary.Unknown results. + resetMaybeStack(/*markAllAsSucceeded*/ true); + } + else { + resetMaybeStack(/*markAllAsSucceeded*/ false); + } + } + // Note: it's intentional that we don't reset in the else case; + // we leave them on the stack such that when we hit depth zero + // above, we can report all of them as successful. + } + else { + // A false result goes straight into global cache (when something is false under + // assumptions it will also be false without assumptions) + relation.set(id, (reportErrors ? RelationComparisonResult.Reported : 0) | RelationComparisonResult.Failed | propagatingVarianceFlags); + relationCount--; + resetMaybeStack(/*markAllAsSucceeded*/ false); + } + return result; + + function resetMaybeStack(markAllAsSucceeded: boolean) { + for (let i = maybeStart; i < maybeCount; i++) { + maybeKeysSet.delete(maybeKeys[i]); + if (markAllAsSucceeded) { + relation.set(maybeKeys[i], RelationComparisonResult.Succeeded | propagatingVarianceFlags); + relationCount--; + } + } + maybeCount = maybeStart; + } + } + + function structuredTypeRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const saveErrorInfo = captureErrorCalculationState(); + let result = structuredTypeRelatedToWorker(source, target, reportErrors, intersectionState, saveErrorInfo); + if (relation !== identityRelation) { + // The combined constraint of an intersection type is the intersection of the constraints of + // the constituents. When an intersection type contains instantiable types with union type + // constraints, there are situations where we need to examine the combined constraint. One is + // when the target is a union type. Another is when the intersection contains types belonging + // to one of the disjoint domains. For example, given type variables T and U, each with the + // constraint 'string | number', the combined constraint of 'T & U' is 'string | number' and + // we need to check this constraint against a union on the target side. Also, given a type + // variable V constrained to 'string | number', 'V & number' has a combined constraint of + // 'string & number | number & number' which reduces to just 'number'. + // This also handles type parameters, as a type parameter with a union constraint compared against a union + // needs to have its constraint hoisted into an intersection with said type parameter, this way + // the type param can be compared with itself in the target (with the influence of its constraint to match other parts) + // For example, if `T extends 1 | 2` and `U extends 2 | 3` and we compare `T & U` to `T & U & (1 | 2 | 3)` + if (!result && (source.flags & TypeFlags.Intersection || source.flags & TypeFlags.TypeParameter && target.flags & TypeFlags.Union)) { + const constraint = getEffectiveConstraintOfIntersection(source.flags & TypeFlags.Intersection ? (source as IntersectionType).types : [source], !!(target.flags & TypeFlags.Union)); + if (constraint && everyType(constraint, c => c !== source)) { // Skip comparison if expansion contains the source itself + // TODO: Stack errors so we get a pyramid for the "normal" comparison above, _and_ a second for this + result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + } + } + // When the target is an intersection we need an extra property check in order to detect nested excess + // properties and nested weak types. The following are motivating examples that all should be errors, but + // aren't without this extra property check: + // + // let obj: { a: { x: string } } & { c: number } = { a: { x: 'hello', y: 2 }, c: 5 }; // Nested excess property + // + // declare let wrong: { a: { y: string } }; + // let weak: { a?: { x?: number } } & { c?: string } = wrong; // Nested weak object type + // + if ( + result && !(intersectionState & IntersectionState.Target) && target.flags & TypeFlags.Intersection && + !isGenericObjectType(target) && source.flags & (TypeFlags.Object | TypeFlags.Intersection) + ) { + result &= propertiesRelatedTo(source, target, reportErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ false, IntersectionState.None); + if (result && isObjectLiteralType(source) && getObjectFlags(source) & ObjectFlags.FreshLiteral) { + result &= indexSignaturesRelatedTo(source, target, /*sourceIsPrimitive*/ false, reportErrors, IntersectionState.None); + } + } + // When the source is an intersection we need an extra check of any optional properties in the target to + // detect possible mismatched property types. For example: + // + // function foo(x: { a?: string }, y: T & { a: boolean }) { + // x = y; // Mismatched property in source intersection + // } + // + else if ( + result && isNonGenericObjectType(target) && !isArrayOrTupleType(target) && + source.flags & TypeFlags.Intersection && getApparentType(source).flags & TypeFlags.StructuredType && + !some((source as IntersectionType).types, t => t === target || !!(getObjectFlags(t) & ObjectFlags.NonInferrableType)) + ) { + result &= propertiesRelatedTo(source, target, reportErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ true, intersectionState); + } + } + if (result) { + resetErrorInfo(saveErrorInfo); + } + return result; + } + + function getApparentMappedTypeKeys(nameType: Type, targetType: MappedType) { + const modifiersType = getApparentType(getModifiersTypeFromMappedType(targetType)); + const mappedKeys: Type[] = []; + forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType( + modifiersType, + TypeFlags.StringOrNumberLiteralOrUnique, + /*stringsOnly*/ false, + t => void mappedKeys.push(instantiateType(nameType, appendTypeMapping(targetType.mapper, getTypeParameterFromMappedType(targetType), t))), + ); + return getUnionType(mappedKeys); + } + + function structuredTypeRelatedToWorker(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState, saveErrorInfo: ReturnType): Ternary { + let result: Ternary; + let originalErrorInfo: DiagnosticMessageChain | undefined; + let varianceCheckFailed = false; + let sourceFlags = source.flags; + const targetFlags = target.flags; + if (relation === identityRelation) { + // We've already checked that source.flags and target.flags are identical + if (sourceFlags & TypeFlags.UnionOrIntersection) { + let result = eachTypeRelatedToSomeType(source as UnionOrIntersectionType, target as UnionOrIntersectionType); + if (result) { + result &= eachTypeRelatedToSomeType(target as UnionOrIntersectionType, source as UnionOrIntersectionType); + } + return result; + } + if (sourceFlags & TypeFlags.Index) { + return isRelatedTo((source as IndexType).type, (target as IndexType).type, RecursionFlags.Both, /*reportErrors*/ false); + } + if (sourceFlags & TypeFlags.IndexedAccess) { + if (result = isRelatedTo((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType, RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + } + if (sourceFlags & TypeFlags.Conditional) { + if ((source as ConditionalType).root.isDistributive === (target as ConditionalType).root.isDistributive) { + if (result = isRelatedTo((source as ConditionalType).checkType, (target as ConditionalType).checkType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo((source as ConditionalType).extendsType, (target as ConditionalType).extendsType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo(getTrueTypeFromConditionalType(source as ConditionalType), getTrueTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + } + } + } + } + if (sourceFlags & TypeFlags.Substitution) { + if (result = isRelatedTo((source as SubstitutionType).baseType, (target as SubstitutionType).baseType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo((source as SubstitutionType).constraint, (target as SubstitutionType).constraint, RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + } + if (!(sourceFlags & TypeFlags.Object)) { + return Ternary.False; + } + } + else if (sourceFlags & TypeFlags.UnionOrIntersection || targetFlags & TypeFlags.UnionOrIntersection) { + if (result = unionOrIntersectionRelatedTo(source, target, reportErrors, intersectionState)) { + return result; + } + // The ordered decomposition above doesn't handle all cases. Specifically, we also need to handle: + // Source is instantiable (e.g. source has union or intersection constraint). + // Source is an object, target is a union (e.g. { a, b: boolean } <=> { a, b: true } | { a, b: false }). + // Source is an intersection, target is an object (e.g. { a } & { b } <=> { a, b }). + // Source is an intersection, target is a union (e.g. { a } & { b: boolean } <=> { a, b: true } | { a, b: false }). + // Source is an intersection, target instantiable (e.g. string & { tag } <=> T["a"] constrained to string & { tag }). + if ( + !(sourceFlags & TypeFlags.Instantiable || + sourceFlags & TypeFlags.Object && targetFlags & TypeFlags.Union || + sourceFlags & TypeFlags.Intersection && targetFlags & (TypeFlags.Object | TypeFlags.Union | TypeFlags.Instantiable)) + ) { + return Ternary.False; + } + } + + // We limit alias variance probing to only object and conditional types since their alias behavior + // is more predictable than other, interned types, which may or may not have an alias depending on + // the order in which things were checked. + if ( + sourceFlags & (TypeFlags.Object | TypeFlags.Conditional) && source.aliasSymbol && source.aliasTypeArguments && + source.aliasSymbol === target.aliasSymbol && !(isMarkerType(source) || isMarkerType(target)) + ) { + const variances = getAliasVariances(source.aliasSymbol); + if (variances === emptyArray) { + return Ternary.Unknown; + } + const params = getSymbolLinks(source.aliasSymbol).typeParameters!; + const minParams = getMinTypeArgumentCount(params); + const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + const varianceResult = relateVariances(sourceTypes, targetTypes, variances, intersectionState); + if (varianceResult !== undefined) { + return varianceResult; + } + } + + // For a generic type T and a type U that is assignable to T, [...U] is assignable to T, U is assignable to readonly [...T], + // and U is assignable to [...T] when U is constrained to a mutable array or tuple type. + if ( + isSingleElementGenericTupleType(source) && !source.target.readonly && (result = isRelatedTo(getTypeArguments(source)[0], target, RecursionFlags.Source)) || + isSingleElementGenericTupleType(target) && (target.target.readonly || isMutableArrayOrTuple(getBaseConstraintOfType(source) || source)) && (result = isRelatedTo(source, getTypeArguments(target)[0], RecursionFlags.Target)) + ) { + return result; + } + + if (targetFlags & TypeFlags.TypeParameter) { + // A source type { [P in Q]: X } is related to a target type T if keyof T is related to Q and X is related to T[Q]. + if (getObjectFlags(source) & ObjectFlags.Mapped && !(source as MappedType).declaration.nameType && isRelatedTo(getIndexType(target), getConstraintTypeFromMappedType(source as MappedType), RecursionFlags.Both)) { + if (!(getMappedTypeModifiers(source as MappedType) & MappedTypeModifiers.IncludeOptional)) { + const templateType = getTemplateTypeFromMappedType(source as MappedType); + const indexedAccessType = getIndexedAccessType(target, getTypeParameterFromMappedType(source as MappedType)); + if (result = isRelatedTo(templateType, indexedAccessType, RecursionFlags.Both, reportErrors)) { + return result; + } + } + } + if (relation === comparableRelation && sourceFlags & TypeFlags.TypeParameter) { + // This is a carve-out in comparability to essentially forbid comparing a type parameter + // with another type parameter unless one extends the other. (Remember: comparability is mostly bidirectional!) + let constraint = getConstraintOfTypeParameter(source); + if (constraint) { + while (constraint && someType(constraint, c => !!(c.flags & TypeFlags.TypeParameter))) { + if (result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false)) { + return result; + } + constraint = getConstraintOfTypeParameter(constraint); + } + } + return Ternary.False; + } + } + else if (targetFlags & TypeFlags.Index) { + const targetType = (target as IndexType).type; + // A keyof S is related to a keyof T if T is related to S. + if (sourceFlags & TypeFlags.Index) { + if (result = isRelatedTo(targetType, (source as IndexType).type, RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + if (isTupleType(targetType)) { + // An index type can have a tuple type target when the tuple type contains variadic elements. + // Check if the source is related to the known keys of the tuple type. + if (result = isRelatedTo(source, getKnownKeysOfTupleType(targetType), RecursionFlags.Target, reportErrors)) { + return result; + } + } + else { + // A type S is assignable to keyof T if S is assignable to keyof C, where C is the + // simplified form of T or, if T doesn't simplify, the constraint of T. + const constraint = getSimplifiedTypeOrConstraint(targetType); + if (constraint) { + // We require Ternary.True here such that circular constraints don't cause + // false positives. For example, given 'T extends { [K in keyof T]: string }', + // 'keyof T' has itself as its constraint and produces a Ternary.Maybe when + // related to other types. + if (isRelatedTo(source, getIndexType(constraint, (target as IndexType).indexFlags | IndexFlags.NoReducibleCheck), RecursionFlags.Target, reportErrors) === Ternary.True) { + return Ternary.True; + } + } + else if (isGenericMappedType(targetType)) { + // generic mapped types that don't simplify or have a constraint still have a very simple set of keys we can compare against + // - their nameType or constraintType. + // In many ways, this comparison is a deferred version of what `getIndexTypeForMappedType` does to actually resolve the keys for _non_-generic types + + const nameType = getNameTypeFromMappedType(targetType); + const constraintType = getConstraintTypeFromMappedType(targetType); + let targetKeys; + if (nameType && isMappedTypeWithKeyofConstraintDeclaration(targetType)) { + // we need to get the apparent mappings and union them with the generic mappings, since some properties may be + // missing from the `constraintType` which will otherwise be mapped in the object + const mappedKeys = getApparentMappedTypeKeys(nameType, targetType); + // We still need to include the non-apparent (and thus still generic) keys in the target side of the comparison (in case they're in the source side) + targetKeys = getUnionType([mappedKeys, nameType]); + } + else { + targetKeys = nameType || constraintType; + } + if (isRelatedTo(source, targetKeys, RecursionFlags.Target, reportErrors) === Ternary.True) { + return Ternary.True; + } + } + } + } + else if (targetFlags & TypeFlags.IndexedAccess) { + if (sourceFlags & TypeFlags.IndexedAccess) { + // Relate components directly before falling back to constraint relationships + // A type S[K] is related to a type T[J] if S is related to T and K is related to J. + if (result = isRelatedTo((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType, RecursionFlags.Both, reportErrors)) { + result &= isRelatedTo((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType, RecursionFlags.Both, reportErrors); + } + if (result) { + return result; + } + if (reportErrors) { + originalErrorInfo = errorInfo; + } + } + // A type S is related to a type T[K] if S is related to C, where C is the base + // constraint of T[K] for writing. + if (relation === assignableRelation || relation === comparableRelation) { + const objectType = (target as IndexedAccessType).objectType; + const indexType = (target as IndexedAccessType).indexType; + const baseObjectType = getBaseConstraintOfType(objectType) || objectType; + const baseIndexType = getBaseConstraintOfType(indexType) || indexType; + if (!isGenericObjectType(baseObjectType) && !isGenericIndexType(baseIndexType)) { + const accessFlags = AccessFlags.Writing | (baseObjectType !== objectType ? AccessFlags.NoIndexSignatures : 0); + const constraint = getIndexedAccessTypeOrUndefined(baseObjectType, baseIndexType, accessFlags); + if (constraint) { + if (reportErrors && originalErrorInfo) { + // create a new chain for the constraint error + resetErrorInfo(saveErrorInfo); + } + if (result = isRelatedTo(source, constraint, RecursionFlags.Target, reportErrors, /*headMessage*/ undefined, intersectionState)) { + return result; + } + // prefer the shorter chain of the constraint comparison chain, and the direct comparison chain + if (reportErrors && originalErrorInfo && errorInfo) { + errorInfo = countMessageChainBreadth([originalErrorInfo]) <= countMessageChainBreadth([errorInfo]) ? originalErrorInfo : errorInfo; + } + } + } + } + if (reportErrors) { + originalErrorInfo = undefined; + } + } + else if (isGenericMappedType(target) && relation !== identityRelation) { + // Check if source type `S` is related to target type `{ [P in Q]: T }` or `{ [P in Q as R]: T}`. + const keysRemapped = !!target.declaration.nameType; + const templateType = getTemplateTypeFromMappedType(target); + const modifiers = getMappedTypeModifiers(target); + if (!(modifiers & MappedTypeModifiers.ExcludeOptional)) { + // If the mapped type has shape `{ [P in Q]: T[P] }`, + // source `S` is related to target if `T` = `S`, i.e. `S` is related to `{ [P in Q]: S[P] }`. + if ( + !keysRemapped && templateType.flags & TypeFlags.IndexedAccess && (templateType as IndexedAccessType).objectType === source && + (templateType as IndexedAccessType).indexType === getTypeParameterFromMappedType(target) + ) { + return Ternary.True; + } + if (!isGenericMappedType(source)) { + // If target has shape `{ [P in Q as R]: T}`, then its keys have type `R`. + // If target has shape `{ [P in Q]: T }`, then its keys have type `Q`. + const targetKeys = keysRemapped ? getNameTypeFromMappedType(target)! : getConstraintTypeFromMappedType(target); + // Type of the keys of source type `S`, i.e. `keyof S`. + const sourceKeys = getIndexType(source, IndexFlags.NoIndexSignatures); + const includeOptional = modifiers & MappedTypeModifiers.IncludeOptional; + const filteredByApplicability = includeOptional ? intersectTypes(targetKeys, sourceKeys) : undefined; + // A source type `S` is related to a target type `{ [P in Q]: T }` if `Q` is related to `keyof S` and `S[Q]` is related to `T`. + // A source type `S` is related to a target type `{ [P in Q as R]: T }` if `R` is related to `keyof S` and `S[R]` is related to `T. + // A source type `S` is related to a target type `{ [P in Q]?: T }` if some constituent `Q'` of `Q` is related to `keyof S` and `S[Q']` is related to `T`. + // A source type `S` is related to a target type `{ [P in Q as R]?: T }` if some constituent `R'` of `R` is related to `keyof S` and `S[R']` is related to `T`. + if ( + includeOptional + ? !(filteredByApplicability!.flags & TypeFlags.Never) + : isRelatedTo(targetKeys, sourceKeys, RecursionFlags.Both) + ) { + const templateType = getTemplateTypeFromMappedType(target); + const typeParameter = getTypeParameterFromMappedType(target); + + // Fastpath: When the template type has the form `Obj[P]` where `P` is the mapped type parameter, directly compare source `S` with `Obj` + // to avoid creating the (potentially very large) number of new intermediate types made by manufacturing `S[P]`. + const nonNullComponent = extractTypesOfKind(templateType, ~TypeFlags.Nullable); + if (!keysRemapped && nonNullComponent.flags & TypeFlags.IndexedAccess && (nonNullComponent as IndexedAccessType).indexType === typeParameter) { + if (result = isRelatedTo(source, (nonNullComponent as IndexedAccessType).objectType, RecursionFlags.Target, reportErrors)) { + return result; + } + } + else { + // We need to compare the type of a property on the source type `S` to the type of the same property on the target type, + // so we need to construct an indexing type representing a property, and then use indexing type to index the source type for comparison. + + // If the target type has shape `{ [P in Q]: T }`, then a property of the target has type `P`. + // If the target type has shape `{ [P in Q]?: T }`, then a property of the target has type `P`, + // but the property is optional, so we only want to compare properties `P` that are common between `keyof S` and `Q`. + // If the target type has shape `{ [P in Q as R]: T }`, then a property of the target has type `R`. + // If the target type has shape `{ [P in Q as R]?: T }`, then a property of the target has type `R`, + // but the property is optional, so we only want to compare properties `R` that are common between `keyof S` and `R`. + const indexingType = keysRemapped + ? (filteredByApplicability || targetKeys) + : filteredByApplicability + ? getIntersectionType([filteredByApplicability, typeParameter]) + : typeParameter; + const indexedAccessType = getIndexedAccessType(source, indexingType); + // Compare `S[indexingType]` to `T`, where `T` is the type of a property of the target type. + if (result = isRelatedTo(indexedAccessType, templateType, RecursionFlags.Both, reportErrors)) { + return result; + } + } + } + originalErrorInfo = errorInfo; + resetErrorInfo(saveErrorInfo); + } + } + } + else if (targetFlags & TypeFlags.Conditional) { + // If we reach 10 levels of nesting for the same conditional type, assume it is an infinitely expanding recursive + // conditional type and bail out with a Ternary.Maybe result. + if (isDeeplyNestedType(target, targetStack, targetDepth, 10)) { + return Ternary.Maybe; + } + const c = target as ConditionalType; + // We check for a relationship to a conditional type target only when the conditional type has no + // 'infer' positions, is not distributive or is distributive but doesn't reference the check type + // parameter in either of the result types, and the source isn't an instantiation of the same + // conditional type (as happens when computing variance). + if (!c.root.inferTypeParameters && !isDistributionDependent(c.root) && !(source.flags & TypeFlags.Conditional && (source as ConditionalType).root === c.root)) { + // Check if the conditional is always true or always false but still deferred for distribution purposes. + const skipTrue = !isTypeAssignableTo(getPermissiveInstantiation(c.checkType), getPermissiveInstantiation(c.extendsType)); + const skipFalse = !skipTrue && isTypeAssignableTo(getRestrictiveInstantiation(c.checkType), getRestrictiveInstantiation(c.extendsType)); + // TODO: Find a nice way to include potential conditional type breakdowns in error output, if they seem good (they usually don't) + if (result = skipTrue ? Ternary.True : isRelatedTo(source, getTrueTypeFromConditionalType(c), RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState)) { + result &= skipFalse ? Ternary.True : isRelatedTo(source, getFalseTypeFromConditionalType(c), RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (result) { + return result; + } + } + } + } + else if (targetFlags & TypeFlags.TemplateLiteral) { + if (sourceFlags & TypeFlags.TemplateLiteral) { + if (relation === comparableRelation) { + return templateLiteralTypesDefinitelyUnrelated(source as TemplateLiteralType, target as TemplateLiteralType) ? Ternary.False : Ternary.True; + } + // Report unreliable variance for type variables referenced in template literal type placeholders. + // For example, `foo-${number}` is related to `foo-${string}` even though number isn't related to string. + instantiateType(source, reportUnreliableMapper); + } + if (isTypeMatchedByTemplateLiteralType(source, target as TemplateLiteralType)) { + return Ternary.True; + } + } + else if (target.flags & TypeFlags.StringMapping) { + if (!(source.flags & TypeFlags.StringMapping)) { + if (isMemberOfStringMapping(source, target)) { + return Ternary.True; + } + } + } + + if (sourceFlags & TypeFlags.TypeVariable) { + // IndexedAccess comparisons are handled above in the `targetFlags & TypeFlage.IndexedAccess` branch + if (!(sourceFlags & TypeFlags.IndexedAccess && targetFlags & TypeFlags.IndexedAccess)) { + const constraint = getConstraintOfType(source as TypeVariable) || unknownType; + // hi-speed no-this-instantiation check (less accurate, but avoids costly `this`-instantiation when the constraint will suffice), see #28231 for report on why this is needed + if (result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState)) { + return result; + } + // slower, fuller, this-instantiated check (necessary when comparing raw `this` types from base classes), see `subclassWithPolymorphicThisIsAssignable.ts` test for example + else if (result = isRelatedTo(getTypeWithThisArgument(constraint, source), target, RecursionFlags.Source, reportErrors && constraint !== unknownType && !(targetFlags & sourceFlags & TypeFlags.TypeParameter), /*headMessage*/ undefined, intersectionState)) { + return result; + } + if (isMappedTypeGenericIndexedAccess(source)) { + // For an indexed access type { [P in K]: E}[X], above we have already explored an instantiation of E with X + // substituted for P. We also want to explore type { [P in K]: E }[C], where C is the constraint of X. + const indexConstraint = getConstraintOfType((source as IndexedAccessType).indexType); + if (indexConstraint) { + if (result = isRelatedTo(getIndexedAccessType((source as IndexedAccessType).objectType, indexConstraint), target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + } + } + } + else if (sourceFlags & TypeFlags.Index) { + const isDeferredMappedIndex = shouldDeferIndexType((source as IndexType).type, (source as IndexType).indexFlags) && getObjectFlags((source as IndexType).type) & ObjectFlags.Mapped; + if (result = isRelatedTo(stringNumberSymbolType, target, RecursionFlags.Source, reportErrors && !isDeferredMappedIndex)) { + return result; + } + if (isDeferredMappedIndex) { + const mappedType = (source as IndexType).type as MappedType; + const nameType = getNameTypeFromMappedType(mappedType); + // Unlike on the target side, on the source side we do *not* include the generic part of the `nameType`, since that comes from a + // (potentially anonymous) mapped type local type parameter, so that'd never assign outside the mapped type body, but we still want to + // allow assignments of index types of identical (or similar enough) mapped types. + // eg, `keyof {[X in keyof A]: Obj[X]}` should be assignable to `keyof {[Y in keyof A]: Tup[Y]}` because both map over the same set of keys (`keyof A`). + // Without this source-side breakdown, a `keyof {[X in keyof A]: Obj[X]}` style type won't be assignable to anything except itself, which is much too strict. + const sourceMappedKeys = nameType && isMappedTypeWithKeyofConstraintDeclaration(mappedType) ? getApparentMappedTypeKeys(nameType, mappedType) : (nameType || getConstraintTypeFromMappedType(mappedType)); + if (result = isRelatedTo(sourceMappedKeys, target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + } + else if (sourceFlags & TypeFlags.TemplateLiteral && !(targetFlags & TypeFlags.Object)) { + if (!(targetFlags & TypeFlags.TemplateLiteral)) { + const constraint = getBaseConstraintOfType(source); + if (constraint && constraint !== source && (result = isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors))) { + return result; + } + } + } + else if (sourceFlags & TypeFlags.StringMapping) { + if (targetFlags & TypeFlags.StringMapping) { + if ((source as StringMappingType).symbol !== (target as StringMappingType).symbol) { + return Ternary.False; + } + if (result = isRelatedTo((source as StringMappingType).type, (target as StringMappingType).type, RecursionFlags.Both, reportErrors)) { + return result; + } + } + else { + const constraint = getBaseConstraintOfType(source); + if (constraint && (result = isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors))) { + return result; + } + } + } + else if (sourceFlags & TypeFlags.Conditional) { + // If we reach 10 levels of nesting for the same conditional type, assume it is an infinitely expanding recursive + // conditional type and bail out with a Ternary.Maybe result. + if (isDeeplyNestedType(source, sourceStack, sourceDepth, 10)) { + return Ternary.Maybe; + } + if (targetFlags & TypeFlags.Conditional) { + // Two conditional types 'T1 extends U1 ? X1 : Y1' and 'T2 extends U2 ? X2 : Y2' are related if + // one of T1 and T2 is related to the other, U1 and U2 are identical types, X1 is related to X2, + // and Y1 is related to Y2. + const sourceParams = (source as ConditionalType).root.inferTypeParameters; + let sourceExtends = (source as ConditionalType).extendsType; + let mapper: TypeMapper | undefined; + if (sourceParams) { + // If the source has infer type parameters, we instantiate them in the context of the target + const ctx = createInferenceContext(sourceParams, /*signature*/ undefined, InferenceFlags.None, isRelatedToWorker); + inferTypes(ctx.inferences, (target as ConditionalType).extendsType, sourceExtends, InferencePriority.NoConstraints | InferencePriority.AlwaysStrict); + sourceExtends = instantiateType(sourceExtends, ctx.mapper); + mapper = ctx.mapper; + } + if ( + isTypeIdenticalTo(sourceExtends, (target as ConditionalType).extendsType) && + (isRelatedTo((source as ConditionalType).checkType, (target as ConditionalType).checkType, RecursionFlags.Both) || isRelatedTo((target as ConditionalType).checkType, (source as ConditionalType).checkType, RecursionFlags.Both)) + ) { + if (result = isRelatedTo(instantiateType(getTrueTypeFromConditionalType(source as ConditionalType), mapper), getTrueTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, reportErrors)) { + result &= isRelatedTo(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, reportErrors); + } + if (result) { + return result; + } + } + } + // conditionals can be related to one another via normal constraint, as, eg, `A extends B ? O : never` should be assignable to `O` + // when `O` is a conditional (`never` is trivially assignable to `O`, as is `O`!). + const defaultConstraint = getDefaultConstraintOfConditionalType(source as ConditionalType); + if (defaultConstraint) { + if (result = isRelatedTo(defaultConstraint, target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + // conditionals aren't related to one another via distributive constraint as it is much too inaccurate and allows way + // more assignments than are desirable (since it maps the source check type to its constraint, it loses information). + const distributiveConstraint = !(targetFlags & TypeFlags.Conditional) && hasNonCircularBaseConstraint(source) ? getConstraintOfDistributiveConditionalType(source as ConditionalType) : undefined; + if (distributiveConstraint) { + resetErrorInfo(saveErrorInfo); + if (result = isRelatedTo(distributiveConstraint, target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + } + else { + // An empty object type is related to any mapped type that includes a '?' modifier. + if (relation !== subtypeRelation && relation !== strictSubtypeRelation && isPartialMappedType(target) && isEmptyObjectType(source)) { + return Ternary.True; + } + if (isGenericMappedType(target)) { + if (isGenericMappedType(source)) { + if (result = mappedTypeRelatedTo(source, target, reportErrors)) { + return result; + } + } + return Ternary.False; + } + const sourceIsPrimitive = !!(sourceFlags & TypeFlags.Primitive); + if (relation !== identityRelation) { + source = getApparentType(source); + sourceFlags = source.flags; + } + else if (isGenericMappedType(source)) { + return Ternary.False; + } + if ( + getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (source as TypeReference).target === (target as TypeReference).target && + !isTupleType(source) && !(isMarkerType(source) || isMarkerType(target)) + ) { + // When strictNullChecks is disabled, the element type of the empty array literal is undefinedWideningType, + // and an empty array literal wouldn't be assignable to a `never[]` without this check. + if (isEmptyArrayLiteralType(source)) { + return Ternary.True; + } + // We have type references to the same generic type, and the type references are not marker + // type references (which are intended by be compared structurally). Obtain the variance + // information for the type parameters and relate the type arguments accordingly. + const variances = getVariances((source as TypeReference).target); + // We return Ternary.Maybe for a recursive invocation of getVariances (signalled by emptyArray). This + // effectively means we measure variance only from type parameter occurrences that aren't nested in + // recursive instantiations of the generic type. + if (variances === emptyArray) { + return Ternary.Unknown; + } + const varianceResult = relateVariances(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), variances, intersectionState); + if (varianceResult !== undefined) { + return varianceResult; + } + } + else if (isReadonlyArrayType(target) ? everyType(source, isArrayOrTupleType) : isArrayType(target) && everyType(source, t => isTupleType(t) && !t.target.readonly)) { + if (relation !== identityRelation) { + return isRelatedTo(getIndexTypeOfType(source, numberType) || anyType, getIndexTypeOfType(target, numberType) || anyType, RecursionFlags.Both, reportErrors); + } + else { + // By flags alone, we know that the `target` is a readonly array while the source is a normal array or tuple + // or `target` is an array and source is a tuple - in both cases the types cannot be identical, by construction + return Ternary.False; + } + } + else if (isGenericTupleType(source) && isTupleType(target) && !isGenericTupleType(target)) { + const constraint = getBaseConstraintOrType(source); + if (constraint !== source) { + return isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors); + } + } + // A fresh empty object type is never a subtype of a non-empty object type. This ensures fresh({}) <: { [x: string]: xxx } + // but not vice-versa. Without this rule, those types would be mutual subtypes. + else if ((relation === subtypeRelation || relation === strictSubtypeRelation) && isEmptyObjectType(target) && getObjectFlags(target) & ObjectFlags.FreshLiteral && !isEmptyObjectType(source)) { + return Ternary.False; + } + // Even if relationship doesn't hold for unions, intersections, or generic type references, + // it may hold in a structural comparison. + // In a check of the form X = A & B, we will have previously checked if A relates to X or B relates + // to X. Failing both of those we want to check if the aggregation of A and B's members structurally + // relates to X. Thus, we include intersection types on the source side here. + if (sourceFlags & (TypeFlags.Object | TypeFlags.Intersection) && targetFlags & TypeFlags.Object) { + // Report structural errors only if we haven't reported any errors yet + const reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo.errorInfo && !sourceIsPrimitive; + result = propertiesRelatedTo(source, target, reportStructuralErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ false, intersectionState); + if (result) { + result &= signaturesRelatedTo(source, target, SignatureKind.Call, reportStructuralErrors, intersectionState); + if (result) { + result &= signaturesRelatedTo(source, target, SignatureKind.Construct, reportStructuralErrors, intersectionState); + if (result) { + result &= indexSignaturesRelatedTo(source, target, sourceIsPrimitive, reportStructuralErrors, intersectionState); + } + } + } + if (varianceCheckFailed && result) { + errorInfo = originalErrorInfo || errorInfo || saveErrorInfo.errorInfo; // Use variance error (there is no structural one) and return false + } + else if (result) { + return result; + } + } + // If S is an object type and T is a discriminated union, S may be related to T if + // there exists a constituent of T for every combination of the discriminants of S + // with respect to T. We do not report errors here, as we will use the existing + // error result from checking each constituent of the union. + if (sourceFlags & (TypeFlags.Object | TypeFlags.Intersection) && targetFlags & TypeFlags.Union) { + const objectOnlyTarget = extractTypesOfKind(target, TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Substitution); + if (objectOnlyTarget.flags & TypeFlags.Union) { + const result = typeRelatedToDiscriminatedType(source, objectOnlyTarget as UnionType); + if (result) { + return result; + } + } + } + } + return Ternary.False; + + function countMessageChainBreadth(info: DiagnosticMessageChain[] | undefined): number { + if (!info) return 0; + return reduceLeft(info, (value, chain) => value + 1 + countMessageChainBreadth(chain.next), 0); + } + + function relateVariances(sourceTypeArguments: readonly Type[] | undefined, targetTypeArguments: readonly Type[] | undefined, variances: VarianceFlags[], intersectionState: IntersectionState) { + if (result = typeArgumentsRelatedTo(sourceTypeArguments, targetTypeArguments, variances, reportErrors, intersectionState)) { + return result; + } + if (some(variances, v => !!(v & VarianceFlags.AllowsStructuralFallback))) { + // If some type parameter was `Unmeasurable` or `Unreliable`, and we couldn't pass by assuming it was identical, then we + // have to allow a structural fallback check + // We elide the variance-based error elaborations, since those might not be too helpful, since we'll potentially + // be assuming identity of the type parameter. + originalErrorInfo = undefined; + resetErrorInfo(saveErrorInfo); + return undefined; + } + const allowStructuralFallback = targetTypeArguments && hasCovariantVoidArgument(targetTypeArguments, variances); + varianceCheckFailed = !allowStructuralFallback; + // The type arguments did not relate appropriately, but it may be because we have no variance + // information (in which case typeArgumentsRelatedTo defaulted to covariance for all type + // arguments). It might also be the case that the target type has a 'void' type argument for + // a covariant type parameter that is only used in return positions within the generic type + // (in which case any type argument is permitted on the source side). In those cases we proceed + // with a structural comparison. Otherwise, we know for certain the instantiations aren't + // related and we can return here. + if (variances !== emptyArray && !allowStructuralFallback) { + // In some cases generic types that are covariant in regular type checking mode become + // invariant in --strictFunctionTypes mode because one or more type parameters are used in + // both co- and contravariant positions. In order to make it easier to diagnose *why* such + // types are invariant, if any of the type parameters are invariant we reset the reported + // errors and instead force a structural comparison (which will include elaborations that + // reveal the reason). + // We can switch on `reportErrors` here, since varianceCheckFailed guarantees we return `False`, + // we can return `False` early here to skip calculating the structural error message we don't need. + if (varianceCheckFailed && !(reportErrors && some(variances, v => (v & VarianceFlags.VarianceMask) === VarianceFlags.Invariant))) { + return Ternary.False; + } + // We remember the original error information so we can restore it in case the structural + // comparison unexpectedly succeeds. This can happen when the structural comparison result + // is a Ternary.Maybe for example caused by the recursion depth limiter. + originalErrorInfo = errorInfo; + resetErrorInfo(saveErrorInfo); + } + } + } + + // A type [P in S]: X is related to a type [Q in T]: Y if T is related to S and X' is + // related to Y, where X' is an instantiation of X in which P is replaced with Q. Notice + // that S and T are contra-variant whereas X and Y are co-variant. + function mappedTypeRelatedTo(source: MappedType, target: MappedType, reportErrors: boolean): Ternary { + const modifiersRelated = relation === comparableRelation || (relation === identityRelation ? getMappedTypeModifiers(source) === getMappedTypeModifiers(target) : + getCombinedMappedTypeOptionality(source) <= getCombinedMappedTypeOptionality(target)); + if (modifiersRelated) { + let result: Ternary; + const targetConstraint = getConstraintTypeFromMappedType(target); + const sourceConstraint = instantiateType(getConstraintTypeFromMappedType(source), getCombinedMappedTypeOptionality(source) < 0 ? reportUnmeasurableMapper : reportUnreliableMapper); + if (result = isRelatedTo(targetConstraint, sourceConstraint, RecursionFlags.Both, reportErrors)) { + const mapper = createTypeMapper([getTypeParameterFromMappedType(source)], [getTypeParameterFromMappedType(target)]); + if (instantiateType(getNameTypeFromMappedType(source), mapper) === instantiateType(getNameTypeFromMappedType(target), mapper)) { + return result & isRelatedTo(instantiateType(getTemplateTypeFromMappedType(source), mapper), getTemplateTypeFromMappedType(target), RecursionFlags.Both, reportErrors); + } + } + } + return Ternary.False; + } + + function typeRelatedToDiscriminatedType(source: Type, target: UnionType) { + // 1. Generate the combinations of discriminant properties & types 'source' can satisfy. + // a. If the number of combinations is above a set limit, the comparison is too complex. + // 2. Filter 'target' to the subset of types whose discriminants exist in the matrix. + // a. If 'target' does not satisfy all discriminants in the matrix, 'source' is not related. + // 3. For each type in the filtered 'target', determine if all non-discriminant properties of + // 'target' are related to a property in 'source'. + // + // NOTE: See ~/tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithDiscriminatedUnion.ts + // for examples. + + const sourceProperties = getPropertiesOfType(source); + const sourcePropertiesFiltered = findDiscriminantProperties(sourceProperties, target); + if (!sourcePropertiesFiltered) return Ternary.False; + + // Though we could compute the number of combinations as we generate + // the matrix, this would incur additional memory overhead due to + // array allocations. To reduce this overhead, we first compute + // the number of combinations to ensure we will not surpass our + // fixed limit before incurring the cost of any allocations: + let numCombinations = 1; + for (const sourceProperty of sourcePropertiesFiltered) { + numCombinations *= countTypes(getNonMissingTypeOfSymbol(sourceProperty)); + if (numCombinations > 25) { + // We've reached the complexity limit. + tracing?.instant(tracing.Phase.CheckTypes, "typeRelatedToDiscriminatedType_DepthLimit", { sourceId: source.id, targetId: target.id, numCombinations }); + return Ternary.False; + } + } + + // Compute the set of types for each discriminant property. + const sourceDiscriminantTypes: Type[][] = new Array(sourcePropertiesFiltered.length); + const excludedProperties = new Set<__String>(); + for (let i = 0; i < sourcePropertiesFiltered.length; i++) { + const sourceProperty = sourcePropertiesFiltered[i]; + const sourcePropertyType = getNonMissingTypeOfSymbol(sourceProperty); + sourceDiscriminantTypes[i] = sourcePropertyType.flags & TypeFlags.Union + ? (sourcePropertyType as UnionType).types + : [sourcePropertyType]; + excludedProperties.add(sourceProperty.escapedName); + } + + // Match each combination of the cartesian product of discriminant properties to one or more + // constituents of 'target'. If any combination does not have a match then 'source' is not relatable. + const discriminantCombinations = cartesianProduct(sourceDiscriminantTypes); + const matchingTypes: Type[] = []; + for (const combination of discriminantCombinations) { + let hasMatch = false; + outer: + for (const type of target.types) { + for (let i = 0; i < sourcePropertiesFiltered.length; i++) { + const sourceProperty = sourcePropertiesFiltered[i]; + const targetProperty = getPropertyOfType(type, sourceProperty.escapedName); + if (!targetProperty) continue outer; + if (sourceProperty === targetProperty) continue; + // We compare the source property to the target in the context of a single discriminant type. + const related = propertyRelatedTo(source, target, sourceProperty, targetProperty, _ => combination[i], /*reportErrors*/ false, IntersectionState.None, /*skipOptional*/ strictNullChecks || relation === comparableRelation); + // If the target property could not be found, or if the properties were not related, + // then this constituent is not a match. + if (!related) { + continue outer; + } + } + pushIfUnique(matchingTypes, type, equateValues); + hasMatch = true; + } + if (!hasMatch) { + // We failed to match any type for this combination. + return Ternary.False; + } + } + + // Compare the remaining non-discriminant properties of each match. + let result = Ternary.True; + for (const type of matchingTypes) { + result &= propertiesRelatedTo(source, type, /*reportErrors*/ false, excludedProperties, /*optionalsOnly*/ false, IntersectionState.None); + if (result) { + result &= signaturesRelatedTo(source, type, SignatureKind.Call, /*reportErrors*/ false, IntersectionState.None); + if (result) { + result &= signaturesRelatedTo(source, type, SignatureKind.Construct, /*reportErrors*/ false, IntersectionState.None); + if (result && !(isTupleType(source) && isTupleType(type))) { + // Comparing numeric index types when both `source` and `type` are tuples is unnecessary as the + // element types should be sufficiently covered by `propertiesRelatedTo`. It also causes problems + // with index type assignability as the types for the excluded discriminants are still included + // in the index type. + result &= indexSignaturesRelatedTo(source, type, /*sourceIsPrimitive*/ false, /*reportErrors*/ false, IntersectionState.None); + } + } + } + if (!result) { + return result; + } + } + return result; + } + + function excludeProperties(properties: Symbol[], excludedProperties: Set<__String> | undefined) { + if (!excludedProperties || properties.length === 0) return properties; + let result: Symbol[] | undefined; + for (let i = 0; i < properties.length; i++) { + if (!excludedProperties.has(properties[i].escapedName)) { + if (result) { + result.push(properties[i]); + } + } + else if (!result) { + result = properties.slice(0, i); + } + } + return result || properties; + } + + function isPropertySymbolTypeRelated(sourceProp: Symbol, targetProp: Symbol, getTypeOfSourceProperty: (sym: Symbol) => Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const targetIsOptional = strictNullChecks && !!(getCheckFlags(targetProp) & CheckFlags.Partial); + const effectiveTarget = addOptionality(getNonMissingTypeOfSymbol(targetProp), /*isProperty*/ false, targetIsOptional); + const effectiveSource = getTypeOfSourceProperty(sourceProp); + return isRelatedTo(effectiveSource, effectiveTarget, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + + function propertyRelatedTo(source: Type, target: Type, sourceProp: Symbol, targetProp: Symbol, getTypeOfSourceProperty: (sym: Symbol) => Type, reportErrors: boolean, intersectionState: IntersectionState, skipOptional: boolean): Ternary { + const sourcePropFlags = getDeclarationModifierFlagsFromSymbol(sourceProp); + const targetPropFlags = getDeclarationModifierFlagsFromSymbol(targetProp); + if (sourcePropFlags & ModifierFlags.Private || targetPropFlags & ModifierFlags.Private) { + if (sourceProp.valueDeclaration !== targetProp.valueDeclaration) { + if (reportErrors) { + if (sourcePropFlags & ModifierFlags.Private && targetPropFlags & ModifierFlags.Private) { + reportError(Diagnostics.Types_have_separate_declarations_of_a_private_property_0, symbolToString(targetProp)); + } + else { + reportError(Diagnostics.Property_0_is_private_in_type_1_but_not_in_type_2, symbolToString(targetProp), typeToString(sourcePropFlags & ModifierFlags.Private ? source : target), typeToString(sourcePropFlags & ModifierFlags.Private ? target : source)); + } + } + return Ternary.False; + } + } + else if (targetPropFlags & ModifierFlags.Protected) { + if (!isValidOverrideOf(sourceProp, targetProp)) { + if (reportErrors) { + reportError(Diagnostics.Property_0_is_protected_but_type_1_is_not_a_class_derived_from_2, symbolToString(targetProp), typeToString(getDeclaringClass(sourceProp) || source), typeToString(getDeclaringClass(targetProp) || target)); + } + return Ternary.False; + } + } + else if (sourcePropFlags & ModifierFlags.Protected) { + if (reportErrors) { + reportError(Diagnostics.Property_0_is_protected_in_type_1_but_public_in_type_2, symbolToString(targetProp), typeToString(source), typeToString(target)); + } + return Ternary.False; + } + + // Ensure {readonly a: whatever} is not a subtype of {a: whatever}, + // while {a: whatever} is a subtype of {readonly a: whatever}. + // This ensures the subtype relationship is ordered, and preventing declaration order + // from deciding which type "wins" in union subtype reduction. + // They're still assignable to one another, since `readonly` doesn't affect assignability. + // This is only applied during the strictSubtypeRelation -- currently used in subtype reduction + if ( + relation === strictSubtypeRelation && + isReadonlySymbol(sourceProp) && !isReadonlySymbol(targetProp) + ) { + return Ternary.False; + } + // If the target comes from a partial union prop, allow `undefined` in the target type + const related = isPropertySymbolTypeRelated(sourceProp, targetProp, getTypeOfSourceProperty, reportErrors, intersectionState); + if (!related) { + if (reportErrors) { + reportIncompatibleError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(targetProp)); + } + return Ternary.False; + } + // When checking for comparability, be more lenient with optional properties. + if (!skipOptional && sourceProp.flags & SymbolFlags.Optional && targetProp.flags & SymbolFlags.ClassMember && !(targetProp.flags & SymbolFlags.Optional)) { + // TypeScript 1.0 spec (April 2014): 3.8.3 + // S is a subtype of a type T, and T is a supertype of S if ... + // S' and T are object types and, for each member M in T.. + // M is a property and S' contains a property N where + // if M is a required property, N is also a required property + // (M - property in T) + // (N - property in S) + if (reportErrors) { + reportError(Diagnostics.Property_0_is_optional_in_type_1_but_required_in_type_2, symbolToString(targetProp), typeToString(source), typeToString(target)); + } + return Ternary.False; + } + return related; + } + + function reportUnmatchedProperty(source: Type, target: Type, unmatchedProperty: Symbol, requireOptionalProperties: boolean) { + let shouldSkipElaboration = false; + // give specific error in case where private names have the same description + if ( + unmatchedProperty.valueDeclaration + && isNamedDeclaration(unmatchedProperty.valueDeclaration) + && isPrivateIdentifier(unmatchedProperty.valueDeclaration.name) + && source.symbol + && source.symbol.flags & SymbolFlags.Class + ) { + const privateIdentifierDescription = unmatchedProperty.valueDeclaration.name.escapedText; + const symbolTableKey = getSymbolNameForPrivateIdentifier(source.symbol, privateIdentifierDescription); + if (symbolTableKey && getPropertyOfType(source, symbolTableKey)) { + const sourceName = factory.getDeclarationName(source.symbol.valueDeclaration); + const targetName = factory.getDeclarationName(target.symbol.valueDeclaration); + reportError( + Diagnostics.Property_0_in_type_1_refers_to_a_different_member_that_cannot_be_accessed_from_within_type_2, + diagnosticName(privateIdentifierDescription), + diagnosticName(sourceName.escapedText === "" ? anon : sourceName), + diagnosticName(targetName.escapedText === "" ? anon : targetName), + ); + return; + } + } + const props = arrayFrom(getUnmatchedProperties(source, target, requireOptionalProperties, /*matchDiscriminantProperties*/ false)); + if ( + !headMessage || (headMessage.code !== Diagnostics.Class_0_incorrectly_implements_interface_1.code && + headMessage.code !== Diagnostics.Class_0_incorrectly_implements_class_1_Did_you_mean_to_extend_1_and_inherit_its_members_as_a_subclass.code) + ) { + shouldSkipElaboration = true; // Retain top-level error for interface implementing issues, otherwise omit it + } + if (props.length === 1) { + const propName = symbolToString(unmatchedProperty, /*enclosingDeclaration*/ undefined, SymbolFlags.None, SymbolFormatFlags.AllowAnyNodeKind | SymbolFormatFlags.WriteComputedProps); + reportError(Diagnostics.Property_0_is_missing_in_type_1_but_required_in_type_2, propName, ...getTypeNamesForErrorDisplay(source, target)); + if (length(unmatchedProperty.declarations)) { + associateRelatedInfo(createDiagnosticForNode(unmatchedProperty.declarations![0], Diagnostics._0_is_declared_here, propName)); + } + if (shouldSkipElaboration && errorInfo) { + overrideNextErrorInfo++; + } + } + else if (tryElaborateArrayLikeErrors(source, target, /*reportErrors*/ false)) { + if (props.length > 5) { // arbitrary cutoff for too-long list form + reportError(Diagnostics.Type_0_is_missing_the_following_properties_from_type_1_Colon_2_and_3_more, typeToString(source), typeToString(target), map(props.slice(0, 4), p => symbolToString(p)).join(", "), props.length - 4); + } + else { + reportError(Diagnostics.Type_0_is_missing_the_following_properties_from_type_1_Colon_2, typeToString(source), typeToString(target), map(props, p => symbolToString(p)).join(", ")); + } + if (shouldSkipElaboration && errorInfo) { + overrideNextErrorInfo++; + } + } + // No array like or unmatched property error - just issue top level error (errorInfo = undefined) + } + + function propertiesRelatedTo(source: Type, target: Type, reportErrors: boolean, excludedProperties: Set<__String> | undefined, optionalsOnly: boolean, intersectionState: IntersectionState): Ternary { + if (relation === identityRelation) { + return propertiesIdenticalTo(source, target, excludedProperties); + } + let result = Ternary.True; + if (isTupleType(target)) { + if (isArrayOrTupleType(source)) { + if (!target.target.readonly && (isReadonlyArrayType(source) || isTupleType(source) && source.target.readonly)) { + return Ternary.False; + } + const sourceArity = getTypeReferenceArity(source); + const targetArity = getTypeReferenceArity(target); + const sourceRestFlag = isTupleType(source) ? source.target.combinedFlags & ElementFlags.Rest : ElementFlags.Rest; + const targetHasRestElement = !!(target.target.combinedFlags & ElementFlags.Variable); + const sourceMinLength = isTupleType(source) ? source.target.minLength : 0; + const targetMinLength = target.target.minLength; + if (!sourceRestFlag && sourceArity < targetMinLength) { + if (reportErrors) { + reportError(Diagnostics.Source_has_0_element_s_but_target_requires_1, sourceArity, targetMinLength); + } + return Ternary.False; + } + if (!targetHasRestElement && targetArity < sourceMinLength) { + if (reportErrors) { + reportError(Diagnostics.Source_has_0_element_s_but_target_allows_only_1, sourceMinLength, targetArity); + } + return Ternary.False; + } + if (!targetHasRestElement && (sourceRestFlag || targetArity < sourceArity)) { + if (reportErrors) { + if (sourceMinLength < targetMinLength) { + reportError(Diagnostics.Target_requires_0_element_s_but_source_may_have_fewer, targetMinLength); + } + else { + reportError(Diagnostics.Target_allows_only_0_element_s_but_source_may_have_more, targetArity); + } + } + return Ternary.False; + } + const sourceTypeArguments = getTypeArguments(source); + const targetTypeArguments = getTypeArguments(target); + const targetStartCount = getStartElementCount(target.target, ElementFlags.NonRest); + const targetEndCount = getEndElementCount(target.target, ElementFlags.NonRest); + let canExcludeDiscriminants = !!excludedProperties; + for (let sourcePosition = 0; sourcePosition < sourceArity; sourcePosition++) { + const sourceFlags = isTupleType(source) ? source.target.elementFlags[sourcePosition] : ElementFlags.Rest; + const sourcePositionFromEnd = sourceArity - 1 - sourcePosition; + + const targetPosition = targetHasRestElement && sourcePosition >= targetStartCount + ? targetArity - 1 - Math.min(sourcePositionFromEnd, targetEndCount) + : sourcePosition; + + const targetFlags = target.target.elementFlags[targetPosition]; + + if (targetFlags & ElementFlags.Variadic && !(sourceFlags & ElementFlags.Variadic)) { + if (reportErrors) { + reportError(Diagnostics.Source_provides_no_match_for_variadic_element_at_position_0_in_target, targetPosition); + } + return Ternary.False; + } + if (sourceFlags & ElementFlags.Variadic && !(targetFlags & ElementFlags.Variable)) { + if (reportErrors) { + reportError(Diagnostics.Variadic_element_at_position_0_in_source_does_not_match_element_at_position_1_in_target, sourcePosition, targetPosition); + } + return Ternary.False; + } + if (targetFlags & ElementFlags.Required && !(sourceFlags & ElementFlags.Required)) { + if (reportErrors) { + reportError(Diagnostics.Source_provides_no_match_for_required_element_at_position_0_in_target, targetPosition); + } + return Ternary.False; + } + // We can only exclude discriminant properties if we have not yet encountered a variable-length element. + if (canExcludeDiscriminants) { + if (sourceFlags & ElementFlags.Variable || targetFlags & ElementFlags.Variable) { + canExcludeDiscriminants = false; + } + if (canExcludeDiscriminants && excludedProperties?.has(("" + sourcePosition) as __String)) { + continue; + } + } + + const sourceType = removeMissingType(sourceTypeArguments[sourcePosition], !!(sourceFlags & targetFlags & ElementFlags.Optional)); + const targetType = targetTypeArguments[targetPosition]; + + const targetCheckType = sourceFlags & ElementFlags.Variadic && targetFlags & ElementFlags.Rest ? createArrayType(targetType) : + removeMissingType(targetType, !!(targetFlags & ElementFlags.Optional)); + const related = isRelatedTo(sourceType, targetCheckType, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + if (reportErrors && (targetArity > 1 || sourceArity > 1)) { + if (targetHasRestElement && sourcePosition >= targetStartCount && sourcePositionFromEnd >= targetEndCount && targetStartCount !== sourceArity - targetEndCount - 1) { + reportIncompatibleError(Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target, targetStartCount, sourceArity - targetEndCount - 1, targetPosition); + } + else { + reportIncompatibleError(Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target, sourcePosition, targetPosition); + } + } + return Ternary.False; + } + result &= related; + } + return result; + } + if (target.target.combinedFlags & ElementFlags.Variable) { + return Ternary.False; + } + } + const requireOptionalProperties = (relation === subtypeRelation || relation === strictSubtypeRelation) && !isObjectLiteralType(source) && !isEmptyArrayLiteralType(source) && !isTupleType(source); + const unmatchedProperty = getUnmatchedProperty(source, target, requireOptionalProperties, /*matchDiscriminantProperties*/ false); + if (unmatchedProperty) { + if (reportErrors && shouldReportUnmatchedPropertyError(source, target)) { + reportUnmatchedProperty(source, target, unmatchedProperty, requireOptionalProperties); + } + return Ternary.False; + } + if (isObjectLiteralType(target)) { + for (const sourceProp of excludeProperties(getPropertiesOfType(source), excludedProperties)) { + if (!getPropertyOfObjectType(target, sourceProp.escapedName)) { + const sourceType = getTypeOfSymbol(sourceProp); + if (!(sourceType.flags & TypeFlags.Undefined)) { + if (reportErrors) { + reportError(Diagnostics.Property_0_does_not_exist_on_type_1, symbolToString(sourceProp), typeToString(target)); + } + return Ternary.False; + } + } + } + } + // We only call this for union target types when we're attempting to do excess property checking - in those cases, we want to get _all possible props_ + // from the target union, across all members + const properties = getPropertiesOfType(target); + const numericNamesOnly = isTupleType(source) && isTupleType(target); + for (const targetProp of excludeProperties(properties, excludedProperties)) { + const name = targetProp.escapedName; + if (!(targetProp.flags & SymbolFlags.Prototype) && (!numericNamesOnly || isNumericLiteralName(name) || name === "length") && (!optionalsOnly || targetProp.flags & SymbolFlags.Optional)) { + const sourceProp = getPropertyOfType(source, name); + if (sourceProp && sourceProp !== targetProp) { + const related = propertyRelatedTo(source, target, sourceProp, targetProp, getNonMissingTypeOfSymbol, reportErrors, intersectionState, relation === comparableRelation); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + } + return result; + } + + function propertiesIdenticalTo(source: Type, target: Type, excludedProperties: Set<__String> | undefined): Ternary { + if (!(source.flags & TypeFlags.Object && target.flags & TypeFlags.Object)) { + return Ternary.False; + } + const sourceProperties = excludeProperties(getPropertiesOfObjectType(source), excludedProperties); + const targetProperties = excludeProperties(getPropertiesOfObjectType(target), excludedProperties); + if (sourceProperties.length !== targetProperties.length) { + return Ternary.False; + } + let result = Ternary.True; + for (const sourceProp of sourceProperties) { + const targetProp = getPropertyOfObjectType(target, sourceProp.escapedName); + if (!targetProp) { + return Ternary.False; + } + const related = compareProperties(sourceProp, targetProp, isRelatedTo); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function signaturesRelatedTo(source: Type, target: Type, kind: SignatureKind, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + if (relation === identityRelation) { + return signaturesIdenticalTo(source, target, kind); + } + if (target === anyFunctionType || source === anyFunctionType) { + return Ternary.True; + } + + const sourceIsJSConstructor = source.symbol && isJSConstructor(source.symbol.valueDeclaration); + const targetIsJSConstructor = target.symbol && isJSConstructor(target.symbol.valueDeclaration); + + const sourceSignatures = getSignaturesOfType( + source, + (sourceIsJSConstructor && kind === SignatureKind.Construct) ? + SignatureKind.Call : kind, + ); + const targetSignatures = getSignaturesOfType( + target, + (targetIsJSConstructor && kind === SignatureKind.Construct) ? + SignatureKind.Call : kind, + ); + + if (kind === SignatureKind.Construct && sourceSignatures.length && targetSignatures.length) { + const sourceIsAbstract = !!(sourceSignatures[0].flags & SignatureFlags.Abstract); + const targetIsAbstract = !!(targetSignatures[0].flags & SignatureFlags.Abstract); + if (sourceIsAbstract && !targetIsAbstract) { + // An abstract constructor type is not assignable to a non-abstract constructor type + // as it would otherwise be possible to new an abstract class. Note that the assignability + // check we perform for an extends clause excludes construct signatures from the target, + // so this check never proceeds. + if (reportErrors) { + reportError(Diagnostics.Cannot_assign_an_abstract_constructor_type_to_a_non_abstract_constructor_type); + } + return Ternary.False; + } + if (!constructorVisibilitiesAreCompatible(sourceSignatures[0], targetSignatures[0], reportErrors)) { + return Ternary.False; + } + } + + let result = Ternary.True; + const incompatibleReporter = kind === SignatureKind.Construct ? reportIncompatibleConstructSignatureReturn : reportIncompatibleCallSignatureReturn; + const sourceObjectFlags = getObjectFlags(source); + const targetObjectFlags = getObjectFlags(target); + if ( + sourceObjectFlags & ObjectFlags.Instantiated && targetObjectFlags & ObjectFlags.Instantiated && source.symbol === target.symbol || + sourceObjectFlags & ObjectFlags.Reference && targetObjectFlags & ObjectFlags.Reference && (source as TypeReference).target === (target as TypeReference).target + ) { + // We have instantiations of the same anonymous type (which typically will be the type of a + // method). Simply do a pairwise comparison of the signatures in the two signature lists instead + // of the much more expensive N * M comparison matrix we explore below. We erase type parameters + // as they are known to always be the same. + Debug.assertEqual(sourceSignatures.length, targetSignatures.length); + for (let i = 0; i < targetSignatures.length; i++) { + const related = signatureRelatedTo(sourceSignatures[i], targetSignatures[i], /*erase*/ true, reportErrors, intersectionState, incompatibleReporter(sourceSignatures[i], targetSignatures[i])); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + else if (sourceSignatures.length === 1 && targetSignatures.length === 1) { + // For simple functions (functions with a single signature) we only erase type parameters for + // the comparable relation. Otherwise, if the source signature is generic, we instantiate it + // in the context of the target signature before checking the relationship. Ideally we'd do + // this regardless of the number of signatures, but the potential costs are prohibitive due + // to the quadratic nature of the logic below. + const eraseGenerics = relation === comparableRelation; + const sourceSignature = first(sourceSignatures); + const targetSignature = first(targetSignatures); + result = signatureRelatedTo(sourceSignature, targetSignature, eraseGenerics, reportErrors, intersectionState, incompatibleReporter(sourceSignature, targetSignature)); + if ( + !result && reportErrors && kind === SignatureKind.Construct && (sourceObjectFlags & targetObjectFlags) && + (targetSignature.declaration?.kind === SyntaxKind.Constructor || sourceSignature.declaration?.kind === SyntaxKind.Constructor) + ) { + const constructSignatureToString = (signature: Signature) => signatureToString(signature, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrowStyleSignature, kind); + reportError(Diagnostics.Type_0_is_not_assignable_to_type_1, constructSignatureToString(sourceSignature), constructSignatureToString(targetSignature)); + reportError(Diagnostics.Types_of_construct_signatures_are_incompatible); + return result; + } + } + else { + outer: + for (const t of targetSignatures) { + const saveErrorInfo = captureErrorCalculationState(); + // Only elaborate errors from the first failure + let shouldElaborateErrors = reportErrors; + for (const s of sourceSignatures) { + const related = signatureRelatedTo(s, t, /*erase*/ true, shouldElaborateErrors, intersectionState, incompatibleReporter(s, t)); + if (related) { + result &= related; + resetErrorInfo(saveErrorInfo); + continue outer; + } + shouldElaborateErrors = false; + } + if (shouldElaborateErrors) { + reportError(Diagnostics.Type_0_provides_no_match_for_the_signature_1, typeToString(source), signatureToString(t, /*enclosingDeclaration*/ undefined, /*flags*/ undefined, kind)); + } + return Ternary.False; + } + } + return result; + } + + function shouldReportUnmatchedPropertyError(source: Type, target: Type): boolean { + const typeCallSignatures = getSignaturesOfStructuredType(source, SignatureKind.Call); + const typeConstructSignatures = getSignaturesOfStructuredType(source, SignatureKind.Construct); + const typeProperties = getPropertiesOfObjectType(source); + if ((typeCallSignatures.length || typeConstructSignatures.length) && !typeProperties.length) { + if ( + (getSignaturesOfType(target, SignatureKind.Call).length && typeCallSignatures.length) || + (getSignaturesOfType(target, SignatureKind.Construct).length && typeConstructSignatures.length) + ) { + return true; // target has similar signature kinds to source, still focus on the unmatched property + } + return false; + } + return true; + } + + function reportIncompatibleCallSignatureReturn(siga: Signature, sigb: Signature) { + if (siga.parameters.length === 0 && sigb.parameters.length === 0) { + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target)); + } + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target)); + } + + function reportIncompatibleConstructSignatureReturn(siga: Signature, sigb: Signature) { + if (siga.parameters.length === 0 && sigb.parameters.length === 0) { + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target)); + } + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target)); + } + + /** + * See signatureAssignableTo, compareSignaturesIdentical + */ + function signatureRelatedTo(source: Signature, target: Signature, erase: boolean, reportErrors: boolean, intersectionState: IntersectionState, incompatibleReporter: (source: Type, target: Type) => void): Ternary { + const checkMode = relation === subtypeRelation ? SignatureCheckMode.StrictTopSignature : + relation === strictSubtypeRelation ? SignatureCheckMode.StrictTopSignature | SignatureCheckMode.StrictArity : + SignatureCheckMode.None; + return compareSignaturesRelated(erase ? getErasedSignature(source) : source, erase ? getErasedSignature(target) : target, checkMode, reportErrors, reportError, incompatibleReporter, isRelatedToWorker, reportUnreliableMapper); + function isRelatedToWorker(source: Type, target: Type, reportErrors?: boolean) { + return isRelatedTo(source, target, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + } + + function signaturesIdenticalTo(source: Type, target: Type, kind: SignatureKind): Ternary { + const sourceSignatures = getSignaturesOfType(source, kind); + const targetSignatures = getSignaturesOfType(target, kind); + if (sourceSignatures.length !== targetSignatures.length) { + return Ternary.False; + } + let result = Ternary.True; + for (let i = 0; i < sourceSignatures.length; i++) { + const related = compareSignaturesIdentical(sourceSignatures[i], targetSignatures[i], /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false, isRelatedTo); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function membersRelatedToIndexInfo(source: Type, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + let result = Ternary.True; + const keyType = targetInfo.keyType; + const props = source.flags & TypeFlags.Intersection ? getPropertiesOfUnionOrIntersectionType(source as IntersectionType) : getPropertiesOfObjectType(source); + for (const prop of props) { + // Skip over ignored JSX and symbol-named members + if (isIgnoredJsxProperty(source, prop)) { + continue; + } + if (isApplicableIndexType(getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique), keyType)) { + const propType = getNonMissingTypeOfSymbol(prop); + const type = exactOptionalPropertyTypes || propType.flags & TypeFlags.Undefined || keyType === numberType || !(prop.flags & SymbolFlags.Optional) + ? propType + : getTypeWithFacts(propType, TypeFacts.NEUndefined); + const related = isRelatedTo(type, targetInfo.type, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + if (reportErrors) { + reportError(Diagnostics.Property_0_is_incompatible_with_index_signature, symbolToString(prop)); + } + return Ternary.False; + } + result &= related; + } + } + for (const info of getIndexInfosOfType(source)) { + if (isApplicableIndexType(info.keyType, keyType)) { + const related = indexInfoRelatedTo(info, targetInfo, reportErrors, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + return result; + } + + function indexInfoRelatedTo(sourceInfo: IndexInfo, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState) { + const related = isRelatedTo(sourceInfo.type, targetInfo.type, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related && reportErrors) { + if (sourceInfo.keyType === targetInfo.keyType) { + reportError(Diagnostics._0_index_signatures_are_incompatible, typeToString(sourceInfo.keyType)); + } + else { + reportError(Diagnostics._0_and_1_index_signatures_are_incompatible, typeToString(sourceInfo.keyType), typeToString(targetInfo.keyType)); + } + } + return related; + } + + function indexSignaturesRelatedTo(source: Type, target: Type, sourceIsPrimitive: boolean, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + if (relation === identityRelation) { + return indexSignaturesIdenticalTo(source, target); + } + const indexInfos = getIndexInfosOfType(target); + const targetHasStringIndex = some(indexInfos, info => info.keyType === stringType); + let result = Ternary.True; + for (const targetInfo of indexInfos) { + const related = relation !== strictSubtypeRelation && !sourceIsPrimitive && targetHasStringIndex && targetInfo.type.flags & TypeFlags.Any ? Ternary.True : + isGenericMappedType(source) && targetHasStringIndex ? isRelatedTo(getTemplateTypeFromMappedType(source), targetInfo.type, RecursionFlags.Both, reportErrors) : + typeRelatedToIndexInfo(source, targetInfo, reportErrors, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function typeRelatedToIndexInfo(source: Type, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const sourceInfo = getApplicableIndexInfo(source, targetInfo.keyType); + if (sourceInfo) { + return indexInfoRelatedTo(sourceInfo, targetInfo, reportErrors, intersectionState); + } + // Intersection constituents are never considered to have an inferred index signature. Also, in the strict subtype relation, + // only fresh object literals are considered to have inferred index signatures. This ensures { [x: string]: xxx } <: {} but + // not vice-versa. Without this rule, those types would be mutual strict subtypes. + if (!(intersectionState & IntersectionState.Source) && (relation !== strictSubtypeRelation || getObjectFlags(source) & ObjectFlags.FreshLiteral) && isObjectTypeWithInferableIndex(source)) { + return membersRelatedToIndexInfo(source, targetInfo, reportErrors, intersectionState); + } + if (reportErrors) { + reportError(Diagnostics.Index_signature_for_type_0_is_missing_in_type_1, typeToString(targetInfo.keyType), typeToString(source)); + } + return Ternary.False; + } + + function indexSignaturesIdenticalTo(source: Type, target: Type): Ternary { + const sourceInfos = getIndexInfosOfType(source); + const targetInfos = getIndexInfosOfType(target); + if (sourceInfos.length !== targetInfos.length) { + return Ternary.False; + } + for (const targetInfo of targetInfos) { + const sourceInfo = getIndexInfoOfType(source, targetInfo.keyType); + if (!(sourceInfo && isRelatedTo(sourceInfo.type, targetInfo.type, RecursionFlags.Both) && sourceInfo.isReadonly === targetInfo.isReadonly)) { + return Ternary.False; + } + } + return Ternary.True; + } + + function constructorVisibilitiesAreCompatible(sourceSignature: Signature, targetSignature: Signature, reportErrors: boolean) { + if (!sourceSignature.declaration || !targetSignature.declaration) { + return true; + } + + const sourceAccessibility = getSelectedEffectiveModifierFlags(sourceSignature.declaration, ModifierFlags.NonPublicAccessibilityModifier); + const targetAccessibility = getSelectedEffectiveModifierFlags(targetSignature.declaration, ModifierFlags.NonPublicAccessibilityModifier); + + // A public, protected and private signature is assignable to a private signature. + if (targetAccessibility === ModifierFlags.Private) { + return true; + } + + // A public and protected signature is assignable to a protected signature. + if (targetAccessibility === ModifierFlags.Protected && sourceAccessibility !== ModifierFlags.Private) { + return true; + } + + // Only a public signature is assignable to public signature. + if (targetAccessibility !== ModifierFlags.Protected && !sourceAccessibility) { + return true; + } + + if (reportErrors) { + reportError(Diagnostics.Cannot_assign_a_0_constructor_type_to_a_1_constructor_type, visibilityToString(sourceAccessibility), visibilityToString(targetAccessibility)); + } + + return false; + } + } + + function typeCouldHaveTopLevelSingletonTypes(type: Type): boolean { + // Okay, yes, 'boolean' is a union of 'true | false', but that's not useful + // in error reporting scenarios. If you need to use this function but that detail matters, + // feel free to add a flag. + if (type.flags & TypeFlags.Boolean) { + return false; + } + + if (type.flags & TypeFlags.UnionOrIntersection) { + return !!forEach((type as IntersectionType).types, typeCouldHaveTopLevelSingletonTypes); + } + + if (type.flags & TypeFlags.Instantiable) { + const constraint = getConstraintOfType(type); + if (constraint && constraint !== type) { + return typeCouldHaveTopLevelSingletonTypes(constraint); + } + } + + return isUnitType(type) || !!(type.flags & TypeFlags.TemplateLiteral) || !!(type.flags & TypeFlags.StringMapping); + } + + function getExactOptionalUnassignableProperties(source: Type, target: Type) { + if (isTupleType(source) && isTupleType(target)) return emptyArray; + return getPropertiesOfType(target) + .filter(targetProp => isExactOptionalPropertyMismatch(getTypeOfPropertyOfType(source, targetProp.escapedName), getTypeOfSymbol(targetProp))); + } + + function isExactOptionalPropertyMismatch(source: Type | undefined, target: Type | undefined) { + return !!source && !!target && maybeTypeOfKind(source, TypeFlags.Undefined) && !!containsMissingType(target); + } + + function getExactOptionalProperties(type: Type) { + return getPropertiesOfType(type).filter(targetProp => containsMissingType(getTypeOfSymbol(targetProp))); + } + + function getBestMatchingType(source: Type, target: UnionOrIntersectionType, isRelatedTo = compareTypesAssignable) { + return findMatchingDiscriminantType(source, target, isRelatedTo) || + findMatchingTypeReferenceOrTypeAliasReference(source, target) || + findBestTypeForObjectLiteral(source, target) || + findBestTypeForInvokable(source, target) || + findMostOverlappyType(source, target); + } + + function discriminateTypeByDiscriminableItems(target: UnionType, discriminators: (readonly [() => Type, __String])[], related: (source: Type, target: Type) => boolean | Ternary) { + const types = target.types; + const include: Ternary[] = types.map(t => t.flags & TypeFlags.Primitive ? Ternary.False : Ternary.True); + for (const [getDiscriminatingType, propertyName] of discriminators) { + // If the remaining target types include at least one with a matching discriminant, eliminate those that + // have non-matching discriminants. This ensures that we ignore erroneous discriminators and gradually + // refine the target set without eliminating every constituent (which would lead to `never`). + let matched = false; + for (let i = 0; i < types.length; i++) { + if (include[i]) { + const targetType = getTypeOfPropertyOrIndexSignatureOfType(types[i], propertyName); + if (targetType && related(getDiscriminatingType(), targetType)) { + matched = true; + } + else { + include[i] = Ternary.Maybe; + } + } + } + // Turn each Ternary.Maybe into Ternary.False if there was a match. Otherwise, revert to Ternary.True. + for (let i = 0; i < types.length; i++) { + if (include[i] === Ternary.Maybe) { + include[i] = matched ? Ternary.False : Ternary.True; + } + } + } + const filtered = contains(include, Ternary.False) ? getUnionType(types.filter((_, i) => include[i]), UnionReduction.None) : target; + return filtered.flags & TypeFlags.Never ? target : filtered; + } + + /** + * A type is 'weak' if it is an object type with at least one optional property + * and no required properties, call/construct signatures or index signatures + */ + function isWeakType(type: Type): boolean { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + return resolved.callSignatures.length === 0 && resolved.constructSignatures.length === 0 && resolved.indexInfos.length === 0 && + resolved.properties.length > 0 && every(resolved.properties, p => !!(p.flags & SymbolFlags.Optional)); + } + if (type.flags & TypeFlags.Substitution) { + return isWeakType((type as SubstitutionType).baseType); + } + if (type.flags & TypeFlags.Intersection) { + return every((type as IntersectionType).types, isWeakType); + } + return false; + } + + function hasCommonProperties(source: Type, target: Type, isComparingJsxAttributes: boolean) { + for (const prop of getPropertiesOfType(source)) { + if (isKnownProperty(target, prop.escapedName, isComparingJsxAttributes)) { + return true; + } + } + return false; + } + + function getVariances(type: GenericType): VarianceFlags[] { + // Arrays and tuples are known to be covariant, no need to spend time computing this. + return type === globalArrayType || type === globalReadonlyArrayType || type.objectFlags & ObjectFlags.Tuple ? + arrayVariances : + getVariancesWorker(type.symbol, type.typeParameters); + } + + function getAliasVariances(symbol: Symbol) { + return getVariancesWorker(symbol, getSymbolLinks(symbol).typeParameters); + } + + // Return an array containing the variance of each type parameter. The variance is effectively + // a digest of the type comparisons that occur for each type argument when instantiations of the + // generic type are structurally compared. We infer the variance information by comparing + // instantiations of the generic type for type arguments with known relations. The function + // returns the emptyArray singleton when invoked recursively for the given generic type. + function getVariancesWorker(symbol: Symbol, typeParameters: readonly TypeParameter[] = emptyArray): VarianceFlags[] { + const links = getSymbolLinks(symbol); + if (!links.variances) { + tracing?.push(tracing.Phase.CheckTypes, "getVariancesWorker", { arity: typeParameters.length, id: getTypeId(getDeclaredTypeOfSymbol(symbol)) }); + const oldVarianceComputation = inVarianceComputation; + const saveResolutionStart = resolutionStart; + if (!inVarianceComputation) { + inVarianceComputation = true; + resolutionStart = resolutionTargets.length; + } + links.variances = emptyArray; + const variances = []; + for (const tp of typeParameters) { + const modifiers = getTypeParameterModifiers(tp); + let variance = modifiers & ModifierFlags.Out ? + modifiers & ModifierFlags.In ? VarianceFlags.Invariant : VarianceFlags.Covariant : + modifiers & ModifierFlags.In ? VarianceFlags.Contravariant : undefined; + if (variance === undefined) { + let unmeasurable = false; + let unreliable = false; + const oldHandler = outofbandVarianceMarkerHandler; + outofbandVarianceMarkerHandler = onlyUnreliable => onlyUnreliable ? unreliable = true : unmeasurable = true; + // We first compare instantiations where the type parameter is replaced with + // marker types that have a known subtype relationship. From this we can infer + // invariance, covariance, contravariance or bivariance. + const typeWithSuper = createMarkerType(symbol, tp, markerSuperType); + const typeWithSub = createMarkerType(symbol, tp, markerSubType); + variance = (isTypeAssignableTo(typeWithSub, typeWithSuper) ? VarianceFlags.Covariant : 0) | + (isTypeAssignableTo(typeWithSuper, typeWithSub) ? VarianceFlags.Contravariant : 0); + // If the instantiations appear to be related bivariantly it may be because the + // type parameter is independent (i.e. it isn't witnessed anywhere in the generic + // type). To determine this we compare instantiations where the type parameter is + // replaced with marker types that are known to be unrelated. + if (variance === VarianceFlags.Bivariant && isTypeAssignableTo(createMarkerType(symbol, tp, markerOtherType), typeWithSuper)) { + variance = VarianceFlags.Independent; + } + outofbandVarianceMarkerHandler = oldHandler; + if (unmeasurable || unreliable) { + if (unmeasurable) { + variance |= VarianceFlags.Unmeasurable; + } + if (unreliable) { + variance |= VarianceFlags.Unreliable; + } + } + } + variances.push(variance); + } + if (!oldVarianceComputation) { + inVarianceComputation = false; + resolutionStart = saveResolutionStart; + } + links.variances = variances; + tracing?.pop({ variances: variances.map(Debug.formatVariance) }); + } + return links.variances; + } + + function createMarkerType(symbol: Symbol, source: TypeParameter, target: Type) { + const mapper = makeUnaryTypeMapper(source, target); + const type = getDeclaredTypeOfSymbol(symbol); + if (isErrorType(type)) { + return type; + } + const result = symbol.flags & SymbolFlags.TypeAlias ? + getTypeAliasInstantiation(symbol, instantiateTypes(getSymbolLinks(symbol).typeParameters!, mapper)) : + createTypeReference(type as GenericType, instantiateTypes((type as GenericType).typeParameters, mapper)); + markerTypes.add(getTypeId(result)); + return result; + } + + function isMarkerType(type: Type) { + return markerTypes.has(getTypeId(type)); + } + + function getTypeParameterModifiers(tp: TypeParameter): ModifierFlags { + return reduceLeft(tp.symbol?.declarations, (modifiers, d) => modifiers | getEffectiveModifierFlags(d), ModifierFlags.None) & (ModifierFlags.In | ModifierFlags.Out | ModifierFlags.Const); + } + + // Return true if the given type reference has a 'void' type argument for a covariant type parameter. + // See comment at call in recursiveTypeRelatedTo for when this case matters. + function hasCovariantVoidArgument(typeArguments: readonly Type[], variances: VarianceFlags[]): boolean { + for (let i = 0; i < variances.length; i++) { + if ((variances[i] & VarianceFlags.VarianceMask) === VarianceFlags.Covariant && typeArguments[i].flags & TypeFlags.Void) { + return true; + } + } + return false; + } + + function isUnconstrainedTypeParameter(type: Type) { + return type.flags & TypeFlags.TypeParameter && !getConstraintOfTypeParameter(type as TypeParameter); + } + + function isNonDeferredTypeReference(type: Type): type is TypeReference { + return !!(getObjectFlags(type) & ObjectFlags.Reference) && !(type as TypeReference).node; + } + + function isTypeReferenceWithGenericArguments(type: Type): boolean { + return isNonDeferredTypeReference(type) && some(getTypeArguments(type), t => !!(t.flags & TypeFlags.TypeParameter) || isTypeReferenceWithGenericArguments(t)); + } + + function getGenericTypeReferenceRelationKey(source: TypeReference, target: TypeReference, postFix: string, ignoreConstraints: boolean) { + const typeParameters: Type[] = []; + let constraintMarker = ""; + const sourceId = getTypeReferenceId(source, 0); + const targetId = getTypeReferenceId(target, 0); + return `${constraintMarker}${sourceId},${targetId}${postFix}`; + // getTypeReferenceId(A) returns "111=0-12=1" + // where A.id=111 and number.id=12 + function getTypeReferenceId(type: TypeReference, depth = 0) { + let result = "" + type.target.id; + for (const t of getTypeArguments(type)) { + if (t.flags & TypeFlags.TypeParameter) { + if (ignoreConstraints || isUnconstrainedTypeParameter(t)) { + let index = typeParameters.indexOf(t); + if (index < 0) { + index = typeParameters.length; + typeParameters.push(t); + } + result += "=" + index; + continue; + } + // We mark type references that reference constrained type parameters such that we know to obtain + // and look for a "broadest equivalent key" in the cache. + constraintMarker = "*"; + } + else if (depth < 4 && isTypeReferenceWithGenericArguments(t)) { + result += "<" + getTypeReferenceId(t as TypeReference, depth + 1) + ">"; + continue; + } + result += "-" + t.id; + } + return result; + } + } + + /** + * To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters. + * For other cases, the types ids are used. + */ + function getRelationKey(source: Type, target: Type, intersectionState: IntersectionState, relation: Map, ignoreConstraints: boolean) { + if (relation === identityRelation && source.id > target.id) { + const temp = source; + source = target; + target = temp; + } + const postFix = intersectionState ? ":" + intersectionState : ""; + return isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target) ? + getGenericTypeReferenceRelationKey(source as TypeReference, target as TypeReference, postFix, ignoreConstraints) : + `${source.id},${target.id}${postFix}`; + } + + // Invoke the callback for each underlying property symbol of the given symbol and return the first + // value that isn't undefined. + function forEachProperty(prop: Symbol, callback: (p: Symbol) => T): T | undefined { + if (getCheckFlags(prop) & CheckFlags.Synthetic) { + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.Synthetic + for (const t of (prop as TransientSymbol).links.containingType!.types) { + const p = getPropertyOfType(t, prop.escapedName); + const result = p && forEachProperty(p, callback); + if (result) { + return result; + } + } + return undefined; + } + return callback(prop); + } + + // Return the declaring class type of a property or undefined if property not declared in class + function getDeclaringClass(prop: Symbol) { + return prop.parent && prop.parent.flags & SymbolFlags.Class ? getDeclaredTypeOfSymbol(getParentOfSymbol(prop)!) as InterfaceType : undefined; + } + + // Return the inherited type of the given property or undefined if property doesn't exist in a base class. + function getTypeOfPropertyInBaseClass(property: Symbol) { + const classType = getDeclaringClass(property); + const baseClassType = classType && getBaseTypes(classType)[0]; + return baseClassType && getTypeOfPropertyOfType(baseClassType, property.escapedName); + } + + // Return true if some underlying source property is declared in a class that derives + // from the given base class. + function isPropertyInClassDerivedFrom(prop: Symbol, baseClass: Type | undefined) { + return forEachProperty(prop, sp => { + const sourceClass = getDeclaringClass(sp); + return sourceClass ? hasBaseType(sourceClass, baseClass) : false; + }); + } + + // Return true if source property is a valid override of protected parts of target property. + function isValidOverrideOf(sourceProp: Symbol, targetProp: Symbol) { + return !forEachProperty(targetProp, tp => + getDeclarationModifierFlagsFromSymbol(tp) & ModifierFlags.Protected ? + !isPropertyInClassDerivedFrom(sourceProp, getDeclaringClass(tp)) : false); + } + + // Return true if the given class derives from each of the declaring classes of the protected + // constituents of the given property. + function isClassDerivedFromDeclaringClasses(checkClass: T, prop: Symbol, writing: boolean) { + return forEachProperty(prop, p => + getDeclarationModifierFlagsFromSymbol(p, writing) & ModifierFlags.Protected ? + !hasBaseType(checkClass, getDeclaringClass(p)) : false) ? undefined : checkClass; + } + + // Return true if the given type is deeply nested. We consider this to be the case when the given stack contains + // maxDepth or more occurrences of types with the same recursion identity as the given type. The recursion identity + // provides a shared identity for type instantiations that repeat in some (possibly infinite) pattern. For example, + // in `type Deep = { next: Deep> }`, repeatedly referencing the `next` property leads to an infinite + // sequence of ever deeper instantiations with the same recursion identity (in this case the symbol associated with + // the object type literal). + // A homomorphic mapped type is considered deeply nested if its target type is deeply nested, and an intersection is + // considered deeply nested if any constituent of the intersection is deeply nested. + // It is possible, though highly unlikely, for the deeply nested check to be true in a situation where a chain of + // instantiations is not infinitely expanding. Effectively, we will generate a false positive when two types are + // structurally equal to at least maxDepth levels, but unequal at some level beyond that. + function isDeeplyNestedType(type: Type, stack: Type[], depth: number, maxDepth = 3): boolean { + if (depth >= maxDepth) { + if ((getObjectFlags(type) & ObjectFlags.InstantiatedMapped) === ObjectFlags.InstantiatedMapped) { + type = getMappedTargetWithSymbol(type); + } + if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, t => isDeeplyNestedType(t, stack, depth, maxDepth)); + } + const identity = getRecursionIdentity(type); + let count = 0; + let lastTypeId = 0; + for (let i = 0; i < depth; i++) { + const t = stack[i]; + if (hasMatchingRecursionIdentity(t, identity)) { + // We only count occurrences with a higher type id than the previous occurrence, since higher + // type ids are an indicator of newer instantiations caused by recursion. + if (t.id >= lastTypeId) { + count++; + if (count >= maxDepth) { + return true; + } + } + lastTypeId = t.id; + } + } + } + return false; + } + + // Unwrap nested homomorphic mapped types and return the deepest target type that has a symbol. This better + // preserves unique type identities for mapped types applied to explicitly written object literals. For example + // in `Mapped<{ x: Mapped<{ x: Mapped<{ x: string }>}>}>`, each of the mapped type applications will have a + // unique recursion identity (that of their target object type literal) and thus avoid appearing deeply nested. + function getMappedTargetWithSymbol(type: Type) { + let target; + while ( + (getObjectFlags(type) & ObjectFlags.InstantiatedMapped) === ObjectFlags.InstantiatedMapped && + (target = getModifiersTypeFromMappedType(type as MappedType)) && + (target.symbol || target.flags & TypeFlags.Intersection && some((target as IntersectionType).types, t => !!t.symbol)) + ) { + type = target; + } + return type; + } + + function hasMatchingRecursionIdentity(type: Type, identity: object): boolean { + if ((getObjectFlags(type) & ObjectFlags.InstantiatedMapped) === ObjectFlags.InstantiatedMapped) { + type = getMappedTargetWithSymbol(type); + } + if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, t => hasMatchingRecursionIdentity(t, identity)); + } + return getRecursionIdentity(type) === identity; + } + + // The recursion identity of a type is an object identity that is shared among multiple instantiations of the type. + // We track recursion identities in order to identify deeply nested and possibly infinite type instantiations with + // the same origin. For example, when type parameters are in scope in an object type such as { x: T }, all + // instantiations of that type have the same recursion identity. The default recursion identity is the object + // identity of the type, meaning that every type is unique. Generally, types with constituents that could circularly + // reference the type have a recursion identity that differs from the object identity. + function getRecursionIdentity(type: Type): object { + // Object and array literals are known not to contain recursive references and don't need a recursion identity. + if (type.flags & TypeFlags.Object && !isObjectOrArrayLiteralType(type)) { + if (getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).node) { + // Deferred type references are tracked through their associated AST node. This gives us finer + // granularity than using their associated target because each manifest type reference has a + // unique AST node. + return (type as TypeReference).node!; + } + if (type.symbol && !(getObjectFlags(type) & ObjectFlags.Anonymous && type.symbol.flags & SymbolFlags.Class)) { + // We track object types that have a symbol by that symbol (representing the origin of the type), but + // exclude the static side of a class since it shares its symbol with the instance side. + return type.symbol; + } + if (isTupleType(type)) { + return type.target; + } + } + if (type.flags & TypeFlags.TypeParameter) { + // We use the symbol of the type parameter such that all "fresh" instantiations of that type parameter + // have the same recursion identity. + return type.symbol; + } + if (type.flags & TypeFlags.IndexedAccess) { + // Identity is the leftmost object type in a chain of indexed accesses, eg, in A[P1][P2][P3] it is A. + do { + type = (type as IndexedAccessType).objectType; + } + while (type.flags & TypeFlags.IndexedAccess); + return type; + } + if (type.flags & TypeFlags.Conditional) { + // The root object represents the origin of the conditional type + return (type as ConditionalType).root; + } + return type; + } + + function isPropertyIdenticalTo(sourceProp: Symbol, targetProp: Symbol): boolean { + return compareProperties(sourceProp, targetProp, compareTypesIdentical) !== Ternary.False; + } + + function compareProperties(sourceProp: Symbol, targetProp: Symbol, compareTypes: (source: Type, target: Type) => Ternary): Ternary { + // Two members are considered identical when + // - they are public properties with identical names, optionality, and types, + // - they are private or protected properties originating in the same declaration and having identical types + if (sourceProp === targetProp) { + return Ternary.True; + } + const sourcePropAccessibility = getDeclarationModifierFlagsFromSymbol(sourceProp) & ModifierFlags.NonPublicAccessibilityModifier; + const targetPropAccessibility = getDeclarationModifierFlagsFromSymbol(targetProp) & ModifierFlags.NonPublicAccessibilityModifier; + if (sourcePropAccessibility !== targetPropAccessibility) { + return Ternary.False; + } + if (sourcePropAccessibility) { + if (getTargetSymbol(sourceProp) !== getTargetSymbol(targetProp)) { + return Ternary.False; + } + } + else { + if ((sourceProp.flags & SymbolFlags.Optional) !== (targetProp.flags & SymbolFlags.Optional)) { + return Ternary.False; + } + } + if (isReadonlySymbol(sourceProp) !== isReadonlySymbol(targetProp)) { + return Ternary.False; + } + return compareTypes(getTypeOfSymbol(sourceProp), getTypeOfSymbol(targetProp)); + } + + function isMatchingSignature(source: Signature, target: Signature, partialMatch: boolean) { + const sourceParameterCount = getParameterCount(source); + const targetParameterCount = getParameterCount(target); + const sourceMinArgumentCount = getMinArgumentCount(source); + const targetMinArgumentCount = getMinArgumentCount(target); + const sourceHasRestParameter = hasEffectiveRestParameter(source); + const targetHasRestParameter = hasEffectiveRestParameter(target); + // A source signature matches a target signature if the two signatures have the same number of required, + // optional, and rest parameters. + if ( + sourceParameterCount === targetParameterCount && + sourceMinArgumentCount === targetMinArgumentCount && + sourceHasRestParameter === targetHasRestParameter + ) { + return true; + } + // A source signature partially matches a target signature if the target signature has no fewer required + // parameters + if (partialMatch && sourceMinArgumentCount <= targetMinArgumentCount) { + return true; + } + return false; + } + + /** + * See signatureRelatedTo, compareSignaturesIdentical + */ + function compareSignaturesIdentical(source: Signature, target: Signature, partialMatch: boolean, ignoreThisTypes: boolean, ignoreReturnTypes: boolean, compareTypes: (s: Type, t: Type) => Ternary): Ternary { + // TODO (drosen): De-duplicate code between related functions. + if (source === target) { + return Ternary.True; + } + if (!(isMatchingSignature(source, target, partialMatch))) { + return Ternary.False; + } + // Check that the two signatures have the same number of type parameters. + if (length(source.typeParameters) !== length(target.typeParameters)) { + return Ternary.False; + } + // Check that type parameter constraints and defaults match. If they do, instantiate the source + // signature with the type parameters of the target signature and continue the comparison. + if (target.typeParameters) { + const mapper = createTypeMapper(source.typeParameters!, target.typeParameters); + for (let i = 0; i < target.typeParameters.length; i++) { + const s = source.typeParameters![i]; + const t = target.typeParameters[i]; + if ( + !(s === t || compareTypes(instantiateType(getConstraintFromTypeParameter(s), mapper) || unknownType, getConstraintFromTypeParameter(t) || unknownType) && + compareTypes(instantiateType(getDefaultFromTypeParameter(s), mapper) || unknownType, getDefaultFromTypeParameter(t) || unknownType)) + ) { + return Ternary.False; + } + } + source = instantiateSignature(source, mapper, /*eraseTypeParameters*/ true); + } + let result = Ternary.True; + if (!ignoreThisTypes) { + const sourceThisType = getThisTypeOfSignature(source); + if (sourceThisType) { + const targetThisType = getThisTypeOfSignature(target); + if (targetThisType) { + const related = compareTypes(sourceThisType, targetThisType); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + } + const targetLen = getParameterCount(target); + for (let i = 0; i < targetLen; i++) { + const s = getTypeAtPosition(source, i); + const t = getTypeAtPosition(target, i); + const related = compareTypes(t, s); + if (!related) { + return Ternary.False; + } + result &= related; + } + if (!ignoreReturnTypes) { + const sourceTypePredicate = getTypePredicateOfSignature(source); + const targetTypePredicate = getTypePredicateOfSignature(target); + result &= sourceTypePredicate || targetTypePredicate ? + compareTypePredicatesIdentical(sourceTypePredicate, targetTypePredicate, compareTypes) : + compareTypes(getReturnTypeOfSignature(source), getReturnTypeOfSignature(target)); + } + return result; + } + + function compareTypePredicatesIdentical(source: TypePredicate | undefined, target: TypePredicate | undefined, compareTypes: (s: Type, t: Type) => Ternary): Ternary { + return !(source && target && typePredicateKindsMatch(source, target)) ? Ternary.False : + source.type === target.type ? Ternary.True : + source.type && target.type ? compareTypes(source.type, target.type) : + Ternary.False; + } + + function literalTypesWithSameBaseType(types: Type[]): boolean { + let commonBaseType: Type | undefined; + for (const t of types) { + if (!(t.flags & TypeFlags.Never)) { + const baseType = getBaseTypeOfLiteralType(t); + commonBaseType ??= baseType; + if (baseType === t || baseType !== commonBaseType) { + return false; + } + } + } + return true; + } + + function getCombinedTypeFlags(types: Type[]): TypeFlags { + return reduceLeft(types, (flags, t) => flags | (t.flags & TypeFlags.Union ? getCombinedTypeFlags((t as UnionType).types) : t.flags), 0 as TypeFlags); + } + + function getCommonSupertype(types: Type[]): Type { + if (types.length === 1) { + return types[0]; + } + // Remove nullable types from each of the candidates. + const primaryTypes = strictNullChecks ? sameMap(types, t => filterType(t, u => !(u.flags & TypeFlags.Nullable))) : types; + // When the candidate types are all literal types with the same base type, return a union + // of those literal types. Otherwise, return the leftmost type for which no type to the + // right is a supertype. + const superTypeOrUnion = literalTypesWithSameBaseType(primaryTypes) ? + getUnionType(primaryTypes) : + reduceLeft(primaryTypes, (s, t) => isTypeSubtypeOf(s, t) ? t : s)!; + // Add any nullable types that occurred in the candidates back to the result. + return primaryTypes === types ? superTypeOrUnion : getNullableType(superTypeOrUnion, getCombinedTypeFlags(types) & TypeFlags.Nullable); + } + + // Return the leftmost type for which no type to the right is a subtype. + function getCommonSubtype(types: Type[]) { + return reduceLeft(types, (s, t) => isTypeSubtypeOf(t, s) ? t : s)!; + } + + function isArrayType(type: Type): type is TypeReference { + return !!(getObjectFlags(type) & ObjectFlags.Reference) && ((type as TypeReference).target === globalArrayType || (type as TypeReference).target === globalReadonlyArrayType); + } + + function isReadonlyArrayType(type: Type): boolean { + return !!(getObjectFlags(type) & ObjectFlags.Reference) && (type as TypeReference).target === globalReadonlyArrayType; + } + + function isArrayOrTupleType(type: Type): type is TypeReference { + return isArrayType(type) || isTupleType(type); + } + + function isMutableArrayOrTuple(type: Type): boolean { + return isArrayType(type) && !isReadonlyArrayType(type) || isTupleType(type) && !type.target.readonly; + } + + function getElementTypeOfArrayType(type: Type): Type | undefined { + return isArrayType(type) ? getTypeArguments(type)[0] : undefined; + } + + function isArrayLikeType(type: Type): boolean { + // A type is array-like if it is a reference to the global Array or global ReadonlyArray type, + // or if it is not the undefined or null type and if it is assignable to ReadonlyArray + return isArrayType(type) || !(type.flags & TypeFlags.Nullable) && isTypeAssignableTo(type, anyReadonlyArrayType); + } + + function isMutableArrayLikeType(type: Type): boolean { + // A type is mutable-array-like if it is a reference to the global Array type, or if it is not the + // any, undefined or null type and if it is assignable to Array + return isMutableArrayOrTuple(type) || !(type.flags & (TypeFlags.Any | TypeFlags.Nullable)) && isTypeAssignableTo(type, anyArrayType); + } + + function getSingleBaseForNonAugmentingSubtype(type: Type) { + if (!(getObjectFlags(type) & ObjectFlags.Reference) || !(getObjectFlags((type as TypeReference).target) & ObjectFlags.ClassOrInterface)) { + return undefined; + } + if (getObjectFlags(type) & ObjectFlags.IdenticalBaseTypeCalculated) { + return getObjectFlags(type) & ObjectFlags.IdenticalBaseTypeExists ? (type as TypeReference).cachedEquivalentBaseType : undefined; + } + (type as TypeReference).objectFlags |= ObjectFlags.IdenticalBaseTypeCalculated; + const target = (type as TypeReference).target as InterfaceType; + if (getObjectFlags(target) & ObjectFlags.Class) { + const baseTypeNode = getBaseTypeNodeOfClass(target); + // A base type expression may circularly reference the class itself (e.g. as an argument to function call), so we only + // check for base types specified as simple qualified names. + if (baseTypeNode && baseTypeNode.expression.kind !== SyntaxKind.Identifier && baseTypeNode.expression.kind !== SyntaxKind.PropertyAccessExpression) { + return undefined; + } + } + const bases = getBaseTypes(target); + if (bases.length !== 1) { + return undefined; + } + if (getMembersOfSymbol(type.symbol).size) { + return undefined; // If the interface has any members, they may subtype members in the base, so we should do a full structural comparison + } + let instantiatedBase = !length(target.typeParameters) ? bases[0] : instantiateType(bases[0], createTypeMapper(target.typeParameters!, getTypeArguments(type as TypeReference).slice(0, target.typeParameters!.length))); + if (length(getTypeArguments(type as TypeReference)) > length(target.typeParameters)) { + instantiatedBase = getTypeWithThisArgument(instantiatedBase, last(getTypeArguments(type as TypeReference))); + } + (type as TypeReference).objectFlags |= ObjectFlags.IdenticalBaseTypeExists; + return (type as TypeReference).cachedEquivalentBaseType = instantiatedBase; + } + + function isEmptyLiteralType(type: Type): boolean { + return strictNullChecks ? type === implicitNeverType : type === undefinedWideningType; + } + + function isEmptyArrayLiteralType(type: Type): boolean { + const elementType = getElementTypeOfArrayType(type); + return !!elementType && isEmptyLiteralType(elementType); + } + + function isTupleLikeType(type: Type): boolean { + let lengthType; + return isTupleType(type) || + !!getPropertyOfType(type, "0" as __String) || + isArrayLikeType(type) && !!(lengthType = getTypeOfPropertyOfType(type, "length" as __String)) && everyType(lengthType, t => !!(t.flags & TypeFlags.NumberLiteral)); + } + + function isArrayOrTupleLikeType(type: Type): boolean { + return isArrayLikeType(type) || isTupleLikeType(type); + } + + function getTupleElementType(type: Type, index: number) { + const propType = getTypeOfPropertyOfType(type, "" + index as __String); + if (propType) { + return propType; + } + if (everyType(type, isTupleType)) { + return getTupleElementTypeOutOfStartCount(type, index, compilerOptions.noUncheckedIndexedAccess ? undefinedType : undefined); + } + return undefined; + } + + function isNeitherUnitTypeNorNever(type: Type): boolean { + return !(type.flags & (TypeFlags.Unit | TypeFlags.Never)); + } + + function isUnitType(type: Type): boolean { + return !!(type.flags & TypeFlags.Unit); + } + + function isUnitLikeType(type: Type): boolean { + // Intersections that reduce to 'never' (e.g. 'T & null' where 'T extends {}') are not unit types. + const t = getBaseConstraintOrType(type); + // Scan intersections such that tagged literal types are considered unit types. + return t.flags & TypeFlags.Intersection ? some((t as IntersectionType).types, isUnitType) : isUnitType(t); + } + + function extractUnitType(type: Type) { + return type.flags & TypeFlags.Intersection ? find((type as IntersectionType).types, isUnitType) || type : type; + } + + function isLiteralType(type: Type): boolean { + return type.flags & TypeFlags.Boolean ? true : + type.flags & TypeFlags.Union ? type.flags & TypeFlags.EnumLiteral ? true : every((type as UnionType).types, isUnitType) : + isUnitType(type); + } + + function getBaseTypeOfLiteralType(type: Type): Type { + return type.flags & TypeFlags.EnumLike ? getBaseTypeOfEnumLikeType(type as LiteralType) : + type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? stringType : + type.flags & TypeFlags.NumberLiteral ? numberType : + type.flags & TypeFlags.BigIntLiteral ? bigintType : + type.flags & TypeFlags.BooleanLiteral ? booleanType : + type.flags & TypeFlags.Union ? getBaseTypeOfLiteralTypeUnion(type as UnionType) : + type; + } + + function getBaseTypeOfLiteralTypeUnion(type: UnionType) { + const key = `B${getTypeId(type)}`; + return getCachedType(key) ?? setCachedType(key, mapType(type, getBaseTypeOfLiteralType)); + } + + // This like getBaseTypeOfLiteralType, but instead treats enum literals as strings/numbers instead + // of returning their enum base type (which depends on the types of other literals in the enum). + function getBaseTypeOfLiteralTypeForComparison(type: Type): Type { + return type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? stringType : + type.flags & (TypeFlags.NumberLiteral | TypeFlags.Enum) ? numberType : + type.flags & TypeFlags.BigIntLiteral ? bigintType : + type.flags & TypeFlags.BooleanLiteral ? booleanType : + type.flags & TypeFlags.Union ? mapType(type, getBaseTypeOfLiteralTypeForComparison) : + type; + } + + function getWidenedLiteralType(type: Type): Type { + return type.flags & TypeFlags.EnumLike && isFreshLiteralType(type) ? getBaseTypeOfEnumLikeType(type as LiteralType) : + type.flags & TypeFlags.StringLiteral && isFreshLiteralType(type) ? stringType : + type.flags & TypeFlags.NumberLiteral && isFreshLiteralType(type) ? numberType : + type.flags & TypeFlags.BigIntLiteral && isFreshLiteralType(type) ? bigintType : + type.flags & TypeFlags.BooleanLiteral && isFreshLiteralType(type) ? booleanType : + type.flags & TypeFlags.Union ? mapType(type as UnionType, getWidenedLiteralType) : + type; + } + + function getWidenedUniqueESSymbolType(type: Type): Type { + return type.flags & TypeFlags.UniqueESSymbol ? esSymbolType : + type.flags & TypeFlags.Union ? mapType(type as UnionType, getWidenedUniqueESSymbolType) : + type; + } + + function getWidenedLiteralLikeTypeForContextualType(type: Type, contextualType: Type | undefined) { + if (!isLiteralOfContextualType(type, contextualType)) { + type = getWidenedUniqueESSymbolType(getWidenedLiteralType(type)); + } + return getRegularTypeOfLiteralType(type); + } + + function getWidenedLiteralLikeTypeForContextualReturnTypeIfNeeded(type: Type | undefined, contextualSignatureReturnType: Type | undefined, isAsync: boolean) { + if (type && isUnitType(type)) { + const contextualType = !contextualSignatureReturnType ? undefined : + isAsync ? getPromisedTypeOfPromise(contextualSignatureReturnType) : + contextualSignatureReturnType; + type = getWidenedLiteralLikeTypeForContextualType(type, contextualType); + } + return type; + } + + function getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(type: Type | undefined, contextualSignatureReturnType: Type | undefined, kind: IterationTypeKind, isAsyncGenerator: boolean) { + if (type && isUnitType(type)) { + const contextualType = !contextualSignatureReturnType ? undefined : + getIterationTypeOfGeneratorFunctionReturnType(kind, contextualSignatureReturnType, isAsyncGenerator); + type = getWidenedLiteralLikeTypeForContextualType(type, contextualType); + } + return type; + } + + /** + * Check if a Type was written as a tuple type literal. + * Prefer using isTupleLikeType() unless the use of `elementTypes`/`getTypeArguments` is required. + */ + function isTupleType(type: Type): type is TupleTypeReference { + return !!(getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).target.objectFlags & ObjectFlags.Tuple); + } + + function isGenericTupleType(type: Type): type is TupleTypeReference { + return isTupleType(type) && !!(type.target.combinedFlags & ElementFlags.Variadic); + } + + function isSingleElementGenericTupleType(type: Type): type is TupleTypeReference { + return isGenericTupleType(type) && type.target.elementFlags.length === 1; + } + + function getRestTypeOfTupleType(type: TupleTypeReference) { + return getElementTypeOfSliceOfTupleType(type, type.target.fixedLength); + } + + function getTupleElementTypeOutOfStartCount(type: Type, index: number, undefinedOrMissingType: Type | undefined) { + return mapType(type, t => { + const tupleType = t as TupleTypeReference; + const restType = getRestTypeOfTupleType(tupleType); + if (!restType) { + return undefinedType; + } + if (undefinedOrMissingType && index >= getTotalFixedElementCount(tupleType.target)) { + return getUnionType([restType, undefinedOrMissingType]); + } + return restType; + }); + } + + function getRestArrayTypeOfTupleType(type: TupleTypeReference) { + const restType = getRestTypeOfTupleType(type); + return restType && createArrayType(restType); + } + + function getElementTypeOfSliceOfTupleType(type: TupleTypeReference, index: number, endSkipCount = 0, writing = false, noReductions = false) { + const length = getTypeReferenceArity(type) - endSkipCount; + if (index < length) { + const typeArguments = getTypeArguments(type); + const elementTypes: Type[] = []; + for (let i = index; i < length; i++) { + const t = typeArguments[i]; + elementTypes.push(type.target.elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t); + } + return writing ? getIntersectionType(elementTypes) : getUnionType(elementTypes, noReductions ? UnionReduction.None : UnionReduction.Literal); + } + return undefined; + } + + function isTupleTypeStructureMatching(t1: TupleTypeReference, t2: TupleTypeReference) { + return getTypeReferenceArity(t1) === getTypeReferenceArity(t2) && + every(t1.target.elementFlags, (f, i) => (f & ElementFlags.Variable) === (t2.target.elementFlags[i] & ElementFlags.Variable)); + } + + function isZeroBigInt({ value }: BigIntLiteralType) { + return value.base10Value === "0"; + } + + function removeDefinitelyFalsyTypes(type: Type): Type { + return filterType(type, t => hasTypeFacts(t, TypeFacts.Truthy)); + } + + function extractDefinitelyFalsyTypes(type: Type): Type { + return mapType(type, getDefinitelyFalsyPartOfType); + } + + function getDefinitelyFalsyPartOfType(type: Type): Type { + return type.flags & TypeFlags.String ? emptyStringType : + type.flags & TypeFlags.Number ? zeroType : + type.flags & TypeFlags.BigInt ? zeroBigIntType : + type === regularFalseType || + type === falseType || + type.flags & (TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Null | TypeFlags.AnyOrUnknown) || + type.flags & TypeFlags.StringLiteral && (type as StringLiteralType).value === "" || + type.flags & TypeFlags.NumberLiteral && (type as NumberLiteralType).value === 0 || + type.flags & TypeFlags.BigIntLiteral && isZeroBigInt(type as BigIntLiteralType) ? type : + neverType; + } + + /** + * Add undefined or null or both to a type if they are missing. + * @param type - type to add undefined and/or null to if not present + * @param flags - Either TypeFlags.Undefined or TypeFlags.Null, or both + */ + function getNullableType(type: Type, flags: TypeFlags): Type { + const missing = (flags & ~type.flags) & (TypeFlags.Undefined | TypeFlags.Null); + return missing === 0 ? type : + missing === TypeFlags.Undefined ? getUnionType([type, undefinedType]) : + missing === TypeFlags.Null ? getUnionType([type, nullType]) : + getUnionType([type, undefinedType, nullType]); + } + + function getOptionalType(type: Type, isProperty = false): Type { + Debug.assert(strictNullChecks); + const missingOrUndefined = isProperty ? undefinedOrMissingType : undefinedType; + return type === missingOrUndefined || type.flags & TypeFlags.Union && (type as UnionType).types[0] === missingOrUndefined ? type : getUnionType([type, missingOrUndefined]); + } + + function getGlobalNonNullableTypeInstantiation(type: Type) { + if (!deferredGlobalNonNullableTypeAlias) { + deferredGlobalNonNullableTypeAlias = getGlobalSymbol("NonNullable" as __String, SymbolFlags.TypeAlias, /*diagnostic*/ undefined) || unknownSymbol; + } + return deferredGlobalNonNullableTypeAlias !== unknownSymbol ? + getTypeAliasInstantiation(deferredGlobalNonNullableTypeAlias, [type]) : + getIntersectionType([type, emptyObjectType]); + } + + function getNonNullableType(type: Type): Type { + return strictNullChecks ? getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; + } + + function addOptionalTypeMarker(type: Type) { + return strictNullChecks ? getUnionType([type, optionalType]) : type; + } + + function removeOptionalTypeMarker(type: Type): Type { + return strictNullChecks ? removeType(type, optionalType) : type; + } + + function propagateOptionalTypeMarker(type: Type, node: OptionalChain, wasOptional: boolean) { + return wasOptional ? isOutermostOptionalChain(node) ? getOptionalType(type) : addOptionalTypeMarker(type) : type; + } + + function getOptionalExpressionType(exprType: Type, expression: Expression) { + return isExpressionOfOptionalChainRoot(expression) ? getNonNullableType(exprType) : + isOptionalChain(expression) ? removeOptionalTypeMarker(exprType) : + exprType; + } + + function removeMissingType(type: Type, isOptional: boolean) { + return exactOptionalPropertyTypes && isOptional ? removeType(type, missingType) : type; + } + + function containsMissingType(type: Type) { + return type === missingType || !!(type.flags & TypeFlags.Union) && (type as UnionType).types[0] === missingType; + } + + function removeMissingOrUndefinedType(type: Type): Type { + return exactOptionalPropertyTypes ? removeType(type, missingType) : getTypeWithFacts(type, TypeFacts.NEUndefined); + } + + /** + * Is source potentially coercible to target type under `==`. + * Assumes that `source` is a constituent of a union, hence + * the boolean literal flag on the LHS, but not on the RHS. + * + * This does not fully replicate the semantics of `==`. The + * intention is to catch cases that are clearly not right. + * + * Comparing (string | number) to number should not remove the + * string element. + * + * Comparing (string | number) to 1 will remove the string + * element, though this is not sound. This is a pragmatic + * choice. + * + * @see narrowTypeByEquality + * + * @param source + * @param target + */ + function isCoercibleUnderDoubleEquals(source: Type, target: Type): boolean { + return ((source.flags & (TypeFlags.Number | TypeFlags.String | TypeFlags.BooleanLiteral)) !== 0) + && ((target.flags & (TypeFlags.Number | TypeFlags.String | TypeFlags.Boolean)) !== 0); + } + + /** + * Return true if type was inferred from an object literal, written as an object type literal, or is the shape of a module + * with no call or construct signatures. + */ + function isObjectTypeWithInferableIndex(type: Type): boolean { + const objectFlags = getObjectFlags(type); + return type.flags & TypeFlags.Intersection + ? every((type as IntersectionType).types, isObjectTypeWithInferableIndex) + : !!( + type.symbol + && (type.symbol.flags & (SymbolFlags.ObjectLiteral | SymbolFlags.TypeLiteral | SymbolFlags.Enum | SymbolFlags.ValueModule)) !== 0 + && !(type.symbol.flags & SymbolFlags.Class) + && !typeHasCallOrConstructSignatures(type) + ) || !!( + objectFlags & ObjectFlags.ObjectRestType + ) || !!(objectFlags & ObjectFlags.ReverseMapped && isObjectTypeWithInferableIndex((type as ReverseMappedType).source)); + } + + function createSymbolWithType(source: Symbol, type: Type | undefined) { + const symbol = createSymbol(source.flags, source.escapedName, getCheckFlags(source) & CheckFlags.Readonly); + symbol.declarations = source.declarations; + symbol.parent = source.parent; + symbol.links.type = type; + symbol.links.target = source; + if (source.valueDeclaration) { + symbol.valueDeclaration = source.valueDeclaration; + } + const nameType = getSymbolLinks(source).nameType; + if (nameType) { + symbol.links.nameType = nameType; + } + return symbol; + } + + function transformTypeOfMembers(type: Type, f: (propertyType: Type) => Type) { + const members = createSymbolTable(); + for (const property of getPropertiesOfObjectType(type)) { + const original = getTypeOfSymbol(property); + const updated = f(original); + members.set(property.escapedName, updated === original ? property : createSymbolWithType(property, updated)); + } + return members; + } + + /** + * If the the provided object literal is subject to the excess properties check, + * create a new that is exempt. Recursively mark object literal members as exempt. + * Leave signatures alone since they are not subject to the check. + */ + function getRegularTypeOfObjectLiteral(type: Type): Type { + if (!(isObjectLiteralType(type) && getObjectFlags(type) & ObjectFlags.FreshLiteral)) { + return type; + } + const regularType = (type as FreshObjectLiteralType).regularType; + if (regularType) { + return regularType; + } + + const resolved = type as ResolvedType; + const members = transformTypeOfMembers(type, getRegularTypeOfObjectLiteral); + const regularNew = createAnonymousType(resolved.symbol, members, resolved.callSignatures, resolved.constructSignatures, resolved.indexInfos); + regularNew.flags = resolved.flags; + regularNew.objectFlags |= resolved.objectFlags & ~ObjectFlags.FreshLiteral; + (type as FreshObjectLiteralType).regularType = regularNew; + return regularNew; + } + + function createWideningContext(parent: WideningContext | undefined, propertyName: __String | undefined, siblings: Type[] | undefined): WideningContext { + return { parent, propertyName, siblings, resolvedProperties: undefined }; + } + + function getSiblingsOfContext(context: WideningContext): Type[] { + if (!context.siblings) { + const siblings: Type[] = []; + for (const type of getSiblingsOfContext(context.parent!)) { + if (isObjectLiteralType(type)) { + const prop = getPropertyOfObjectType(type, context.propertyName!); + if (prop) { + forEachType(getTypeOfSymbol(prop), t => { + siblings.push(t); + }); + } + } + } + context.siblings = siblings; + } + return context.siblings; + } + + function getPropertiesOfContext(context: WideningContext): Symbol[] { + if (!context.resolvedProperties) { + const names = new Map<__String, Symbol>(); + for (const t of getSiblingsOfContext(context)) { + if (isObjectLiteralType(t) && !(getObjectFlags(t) & ObjectFlags.ContainsSpread)) { + for (const prop of getPropertiesOfType(t)) { + names.set(prop.escapedName, prop); + } + } + } + context.resolvedProperties = arrayFrom(names.values()); + } + return context.resolvedProperties; + } + + function getWidenedProperty(prop: Symbol, context: WideningContext | undefined): Symbol { + if (!(prop.flags & SymbolFlags.Property)) { + // Since get accessors already widen their return value there is no need to + // widen accessor based properties here. + return prop; + } + const original = getTypeOfSymbol(prop); + const propContext = context && createWideningContext(context, prop.escapedName, /*siblings*/ undefined); + const widened = getWidenedTypeWithContext(original, propContext); + return widened === original ? prop : createSymbolWithType(prop, widened); + } + + function getUndefinedProperty(prop: Symbol) { + const cached = undefinedProperties.get(prop.escapedName); + if (cached) { + return cached; + } + const result = createSymbolWithType(prop, undefinedOrMissingType); + result.flags |= SymbolFlags.Optional; + undefinedProperties.set(prop.escapedName, result); + return result; + } + + function getWidenedTypeOfObjectLiteral(type: Type, context: WideningContext | undefined): Type { + const members = createSymbolTable(); + for (const prop of getPropertiesOfObjectType(type)) { + members.set(prop.escapedName, getWidenedProperty(prop, context)); + } + if (context) { + for (const prop of getPropertiesOfContext(context)) { + if (!members.has(prop.escapedName)) { + members.set(prop.escapedName, getUndefinedProperty(prop)); + } + } + } + const result = createAnonymousType(type.symbol, members, emptyArray, emptyArray, sameMap(getIndexInfosOfType(type), info => createIndexInfo(info.keyType, getWidenedType(info.type), info.isReadonly))); + result.objectFlags |= getObjectFlags(type) & (ObjectFlags.JSLiteral | ObjectFlags.NonInferrableType); // Retain js literal flag through widening + return result; + } + + function getWidenedType(type: Type) { + return getWidenedTypeWithContext(type, /*context*/ undefined); + } + + function getWidenedTypeWithContext(type: Type, context: WideningContext | undefined): Type { + if (getObjectFlags(type) & ObjectFlags.RequiresWidening) { + if (context === undefined && type.widened) { + return type.widened; + } + let result: Type | undefined; + if (type.flags & (TypeFlags.Any | TypeFlags.Nullable)) { + result = anyType; + } + else if (isObjectLiteralType(type)) { + result = getWidenedTypeOfObjectLiteral(type, context); + } + else if (type.flags & TypeFlags.Union) { + const unionContext = context || createWideningContext(/*parent*/ undefined, /*propertyName*/ undefined, (type as UnionType).types); + const widenedTypes = sameMap((type as UnionType).types, t => t.flags & TypeFlags.Nullable ? t : getWidenedTypeWithContext(t, unionContext)); + // Widening an empty object literal transitions from a highly restrictive type to + // a highly inclusive one. For that reason we perform subtype reduction here if the + // union includes empty object types (e.g. reducing {} | string to just {}). + result = getUnionType(widenedTypes, some(widenedTypes, isEmptyObjectType) ? UnionReduction.Subtype : UnionReduction.Literal); + } + else if (type.flags & TypeFlags.Intersection) { + result = getIntersectionType(sameMap((type as IntersectionType).types, getWidenedType)); + } + else if (isArrayOrTupleType(type)) { + result = createTypeReference(type.target, sameMap(getTypeArguments(type), getWidenedType)); + } + if (result && context === undefined) { + type.widened = result; + } + return result || type; + } + return type; + } + + /** + * Reports implicit any errors that occur as a result of widening 'null' and 'undefined' + * to 'any'. A call to reportWideningErrorsInType is normally accompanied by a call to + * getWidenedType. But in some cases getWidenedType is called without reporting errors + * (type argument inference is an example). + * + * The return value indicates whether an error was in fact reported. The particular circumstances + * are on a best effort basis. Currently, if the null or undefined that causes widening is inside + * an object literal property (arbitrarily deeply), this function reports an error. If no error is + * reported, reportImplicitAnyError is a suitable fallback to report a general error. + */ + function reportWideningErrorsInType(type: Type): boolean { + let errorReported = false; + if (getObjectFlags(type) & ObjectFlags.ContainsWideningType) { + if (type.flags & TypeFlags.Union) { + if (some((type as UnionType).types, isEmptyObjectType)) { + errorReported = true; + } + else { + for (const t of (type as UnionType).types) { + errorReported ||= reportWideningErrorsInType(t); + } + } + } + else if (isArrayOrTupleType(type)) { + for (const t of getTypeArguments(type)) { + errorReported ||= reportWideningErrorsInType(t); + } + } + else if (isObjectLiteralType(type)) { + for (const p of getPropertiesOfObjectType(type)) { + const t = getTypeOfSymbol(p); + if (getObjectFlags(t) & ObjectFlags.ContainsWideningType) { + errorReported = reportWideningErrorsInType(t); + if (!errorReported) { + // we need to account for property types coming from object literal type normalization in unions + const valueDeclaration = p.declarations?.find(d => d.symbol.valueDeclaration?.parent === type.symbol.valueDeclaration); + if (valueDeclaration) { + error(valueDeclaration, Diagnostics.Object_literal_s_property_0_implicitly_has_an_1_type, symbolToString(p), typeToString(getWidenedType(t))); + errorReported = true; + } + } + } + } + } + } + return errorReported; + } + + function reportImplicitAny(declaration: Declaration, type: Type, wideningKind?: WideningKind) { + const typeAsString = typeToString(getWidenedType(type)); + if (isInJSFile(declaration) && !isCheckJsEnabledForFile(getSourceFileOfNode(declaration), compilerOptions)) { + // Only report implicit any errors/suggestions in TS and ts-check JS files + return; + } + let diagnostic: DiagnosticMessage; + switch (declaration.kind) { + case SyntaxKind.BinaryExpression: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + diagnostic = noImplicitAny ? Diagnostics.Member_0_implicitly_has_an_1_type : Diagnostics.Member_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; + break; + case SyntaxKind.Parameter: + const param = declaration as ParameterDeclaration; + if (isIdentifier(param.name)) { + const originalKeywordKind = identifierToKeywordKind(param.name); + if ( + (isCallSignatureDeclaration(param.parent) || isMethodSignature(param.parent) || isFunctionTypeNode(param.parent)) && + param.parent.parameters.includes(param) && + (resolveName(param, param.name.escapedText, SymbolFlags.Type, /*nameNotFoundMessage*/ undefined, /*isUse*/ true) || + originalKeywordKind && isTypeNodeKind(originalKeywordKind)) + ) { + const newName = "arg" + param.parent.parameters.indexOf(param); + const typeName = declarationNameToString(param.name) + (param.dotDotDotToken ? "[]" : ""); + errorOrSuggestion(noImplicitAny, declaration, Diagnostics.Parameter_has_a_name_but_no_type_Did_you_mean_0_Colon_1, newName, typeName); + return; + } + } + diagnostic = (declaration as ParameterDeclaration).dotDotDotToken ? + noImplicitAny ? Diagnostics.Rest_parameter_0_implicitly_has_an_any_type : Diagnostics.Rest_parameter_0_implicitly_has_an_any_type_but_a_better_type_may_be_inferred_from_usage : + noImplicitAny ? Diagnostics.Parameter_0_implicitly_has_an_1_type : Diagnostics.Parameter_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; + break; + case SyntaxKind.BindingElement: + diagnostic = Diagnostics.Binding_element_0_implicitly_has_an_1_type; + if (!noImplicitAny) { + // Don't issue a suggestion for binding elements since the codefix doesn't yet support them. + return; + } + break; + case SyntaxKind.JSDocFunctionType: + error(declaration, Diagnostics.Function_type_which_lacks_return_type_annotation_implicitly_has_an_0_return_type, typeAsString); + return; + case SyntaxKind.JSDocSignature: + if (noImplicitAny && isJSDocOverloadTag(declaration.parent)) { + error(declaration.parent.tagName, Diagnostics.This_overload_implicitly_returns_the_type_0_because_it_lacks_a_return_type_annotation, typeAsString); + } + return; + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + if (noImplicitAny && !(declaration as NamedDeclaration).name) { + if (wideningKind === WideningKind.GeneratorYield) { + error(declaration, Diagnostics.Generator_implicitly_has_yield_type_0_because_it_does_not_yield_any_values_Consider_supplying_a_return_type_annotation, typeAsString); + } + else { + error(declaration, Diagnostics.Function_expression_which_lacks_return_type_annotation_implicitly_has_an_0_return_type, typeAsString); + } + return; + } + diagnostic = !noImplicitAny ? Diagnostics._0_implicitly_has_an_1_return_type_but_a_better_type_may_be_inferred_from_usage : + wideningKind === WideningKind.GeneratorYield ? Diagnostics._0_which_lacks_return_type_annotation_implicitly_has_an_1_yield_type : + Diagnostics._0_which_lacks_return_type_annotation_implicitly_has_an_1_return_type; + break; + case SyntaxKind.MappedType: + if (noImplicitAny) { + error(declaration, Diagnostics.Mapped_object_type_implicitly_has_an_any_template_type); + } + return; + default: + diagnostic = noImplicitAny ? Diagnostics.Variable_0_implicitly_has_an_1_type : Diagnostics.Variable_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; + } + errorOrSuggestion(noImplicitAny, declaration, diagnostic, declarationNameToString(getNameOfDeclaration(declaration)), typeAsString); + } + + function reportErrorsFromWidening(declaration: Declaration, type: Type, wideningKind?: WideningKind) { + addLazyDiagnostic(() => { + if (noImplicitAny && getObjectFlags(type) & ObjectFlags.ContainsWideningType && (!wideningKind || !getContextualSignatureForFunctionLikeDeclaration(declaration as FunctionLikeDeclaration))) { + // Report implicit any error within type if possible, otherwise report error on declaration + if (!reportWideningErrorsInType(type)) { + reportImplicitAny(declaration, type, wideningKind); + } + } + }); + } + + function applyToParameterTypes(source: Signature, target: Signature, callback: (s: Type, t: Type) => void) { + const sourceCount = getParameterCount(source); + const targetCount = getParameterCount(target); + const sourceRestType = getEffectiveRestType(source); + const targetRestType = getEffectiveRestType(target); + const targetNonRestCount = targetRestType ? targetCount - 1 : targetCount; + const paramCount = sourceRestType ? targetNonRestCount : Math.min(sourceCount, targetNonRestCount); + const sourceThisType = getThisTypeOfSignature(source); + if (sourceThisType) { + const targetThisType = getThisTypeOfSignature(target); + if (targetThisType) { + callback(sourceThisType, targetThisType); + } + } + for (let i = 0; i < paramCount; i++) { + callback(getTypeAtPosition(source, i), getTypeAtPosition(target, i)); + } + if (targetRestType) { + callback(getRestTypeAtPosition(source, paramCount, /*readonly*/ isConstTypeVariable(targetRestType) && !someType(targetRestType, isMutableArrayLikeType)), targetRestType); + } + } + + function applyToReturnTypes(source: Signature, target: Signature, callback: (s: Type, t: Type) => void) { + const targetTypePredicate = getTypePredicateOfSignature(target); + if (targetTypePredicate) { + const sourceTypePredicate = getTypePredicateOfSignature(source); + if (sourceTypePredicate && typePredicateKindsMatch(sourceTypePredicate, targetTypePredicate) && sourceTypePredicate.type && targetTypePredicate.type) { + callback(sourceTypePredicate.type, targetTypePredicate.type); + return; + } + } + const targetReturnType = getReturnTypeOfSignature(target); + if (couldContainTypeVariables(targetReturnType)) { + callback(getReturnTypeOfSignature(source), targetReturnType); + } + } + + function createInferenceContext(typeParameters: readonly TypeParameter[], signature: Signature | undefined, flags: InferenceFlags, compareTypes?: TypeComparer): InferenceContext { + return createInferenceContextWorker(typeParameters.map(createInferenceInfo), signature, flags, compareTypes || compareTypesAssignable); + } + + function cloneInferenceContext(context: T, extraFlags: InferenceFlags = 0): InferenceContext | T & undefined { + return context && createInferenceContextWorker(map(context.inferences, cloneInferenceInfo), context.signature, context.flags | extraFlags, context.compareTypes); + } + + function createInferenceContextWorker(inferences: InferenceInfo[], signature: Signature | undefined, flags: InferenceFlags, compareTypes: TypeComparer): InferenceContext { + const context: InferenceContext = { + inferences, + signature, + flags, + compareTypes, + mapper: reportUnmeasurableMapper, // initialize to a noop mapper so the context object is available, but the underlying object shape is right upon construction + nonFixingMapper: reportUnmeasurableMapper, + }; + context.mapper = makeFixingMapperForContext(context); + context.nonFixingMapper = makeNonFixingMapperForContext(context); + return context; + } + + function makeFixingMapperForContext(context: InferenceContext) { + return makeDeferredTypeMapper( + map(context.inferences, i => i.typeParameter), + map(context.inferences, (inference, i) => () => { + if (!inference.isFixed) { + // Before we commit to a particular inference (and thus lock out any further inferences), + // we infer from any intra-expression inference sites we have collected. + inferFromIntraExpressionSites(context); + clearCachedInferences(context.inferences); + inference.isFixed = true; + } + return getInferredType(context, i); + }), + ); + } + + function makeNonFixingMapperForContext(context: InferenceContext) { + return makeDeferredTypeMapper( + map(context.inferences, i => i.typeParameter), + map(context.inferences, (_, i) => () => { + return getInferredType(context, i); + }), + ); + } + + function clearCachedInferences(inferences: InferenceInfo[]) { + for (const inference of inferences) { + if (!inference.isFixed) { + inference.inferredType = undefined; + } + } + } + + function addIntraExpressionInferenceSite(context: InferenceContext, node: Expression | MethodDeclaration, type: Type) { + (context.intraExpressionInferenceSites ??= []).push({ node, type }); + } + + // We collect intra-expression inference sites within object and array literals to handle cases where + // inferred types flow between context sensitive element expressions. For example: + // + // declare function foo(arg: [(n: number) => T, (x: T) => void]): void; + // foo([_a => 0, n => n.toFixed()]); + // + // Above, both arrow functions in the tuple argument are context sensitive, thus both are omitted from the + // pass that collects inferences from the non-context sensitive parts of the arguments. In the subsequent + // pass where nothing is omitted, we need to commit to an inference for T in order to contextually type the + // parameter in the second arrow function, but we want to first infer from the return type of the first + // arrow function. This happens automatically when the arrow functions are discrete arguments (because we + // infer from each argument before processing the next), but when the arrow functions are elements of an + // object or array literal, we need to perform intra-expression inferences early. + function inferFromIntraExpressionSites(context: InferenceContext) { + if (context.intraExpressionInferenceSites) { + for (const { node, type } of context.intraExpressionInferenceSites) { + const contextualType = node.kind === SyntaxKind.MethodDeclaration ? + getContextualTypeForObjectLiteralMethod(node as MethodDeclaration, ContextFlags.NoConstraints) : + getContextualType(node, ContextFlags.NoConstraints); + if (contextualType) { + inferTypes(context.inferences, type, contextualType); + } + } + context.intraExpressionInferenceSites = undefined; + } + } + + function createInferenceInfo(typeParameter: TypeParameter): InferenceInfo { + return { + typeParameter, + candidates: undefined, + contraCandidates: undefined, + inferredType: undefined, + priority: undefined, + topLevel: true, + isFixed: false, + impliedArity: undefined, + }; + } + + function cloneInferenceInfo(inference: InferenceInfo): InferenceInfo { + return { + typeParameter: inference.typeParameter, + candidates: inference.candidates && inference.candidates.slice(), + contraCandidates: inference.contraCandidates && inference.contraCandidates.slice(), + inferredType: inference.inferredType, + priority: inference.priority, + topLevel: inference.topLevel, + isFixed: inference.isFixed, + impliedArity: inference.impliedArity, + }; + } + + function cloneInferredPartOfContext(context: InferenceContext): InferenceContext | undefined { + const inferences = filter(context.inferences, hasInferenceCandidates); + return inferences.length ? + createInferenceContextWorker(map(inferences, cloneInferenceInfo), context.signature, context.flags, context.compareTypes) : + undefined; + } + + function getMapperFromContext(context: T): TypeMapper | T & undefined { + return context && context.mapper; + } + + // Return true if the given type could possibly reference a type parameter for which + // we perform type inference (i.e. a type parameter of a generic function). We cache + // results for union and intersection types for performance reasons. + function couldContainTypeVariables(type: Type): boolean { + const objectFlags = getObjectFlags(type); + if (objectFlags & ObjectFlags.CouldContainTypeVariablesComputed) { + return !!(objectFlags & ObjectFlags.CouldContainTypeVariables); + } + const result = !!(type.flags & TypeFlags.Instantiable || + type.flags & TypeFlags.Object && !isNonGenericTopLevelType(type) && ( + objectFlags & ObjectFlags.Reference && ((type as TypeReference).node || some(getTypeArguments(type as TypeReference), couldContainTypeVariables)) || + objectFlags & ObjectFlags.SingleSignatureType && !!length((type as SingleSignatureType).outerTypeParameters) || + objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral) && type.symbol.declarations || + objectFlags & (ObjectFlags.Mapped | ObjectFlags.ReverseMapped | ObjectFlags.ObjectRestType | ObjectFlags.InstantiationExpressionType) + ) || + type.flags & TypeFlags.UnionOrIntersection && !(type.flags & TypeFlags.EnumLiteral) && !isNonGenericTopLevelType(type) && some((type as UnionOrIntersectionType).types, couldContainTypeVariables)); + if (type.flags & TypeFlags.ObjectFlagsType) { + (type as ObjectFlagsType).objectFlags |= ObjectFlags.CouldContainTypeVariablesComputed | (result ? ObjectFlags.CouldContainTypeVariables : 0); + } + return result; + } + + function isNonGenericTopLevelType(type: Type) { + if (type.aliasSymbol && !type.aliasTypeArguments) { + const declaration = getDeclarationOfKind(type.aliasSymbol, SyntaxKind.TypeAliasDeclaration); + return !!(declaration && findAncestor(declaration.parent, n => n.kind === SyntaxKind.SourceFile ? true : n.kind === SyntaxKind.ModuleDeclaration ? false : "quit")); + } + return false; + } + + function isTypeParameterAtTopLevel(type: Type, tp: TypeParameter, depth = 0): boolean { + return !!(type === tp || + type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, t => isTypeParameterAtTopLevel(t, tp, depth)) || + depth < 3 && type.flags & TypeFlags.Conditional && ( + isTypeParameterAtTopLevel(getTrueTypeFromConditionalType(type as ConditionalType), tp, depth + 1) || + isTypeParameterAtTopLevel(getFalseTypeFromConditionalType(type as ConditionalType), tp, depth + 1) + )); + } + + function isTypeParameterAtTopLevelInReturnType(signature: Signature, typeParameter: TypeParameter) { + const typePredicate = getTypePredicateOfSignature(signature); + return typePredicate ? !!typePredicate.type && isTypeParameterAtTopLevel(typePredicate.type, typeParameter) : + isTypeParameterAtTopLevel(getReturnTypeOfSignature(signature), typeParameter); + } + + /** Create an object with properties named in the string literal type. Every property has type `any` */ + function createEmptyObjectTypeFromStringLiteral(type: Type) { + const members = createSymbolTable(); + forEachType(type, t => { + if (!(t.flags & TypeFlags.StringLiteral)) { + return; + } + const name = escapeLeadingUnderscores((t as StringLiteralType).value); + const literalProp = createSymbol(SymbolFlags.Property, name); + literalProp.links.type = anyType; + if (t.symbol) { + literalProp.declarations = t.symbol.declarations; + literalProp.valueDeclaration = t.symbol.valueDeclaration; + } + members.set(name, literalProp); + }); + const indexInfos = type.flags & TypeFlags.String ? [createIndexInfo(stringType, emptyObjectType, /*isReadonly*/ false)] : emptyArray; + return createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, indexInfos); + } + + /** + * Infer a suitable input type for a homomorphic mapped type { [P in keyof T]: X }. We construct + * an object type with the same set of properties as the source type, where the type of each + * property is computed by inferring from the source property type to X for the type + * variable T[P] (i.e. we treat the type T[P] as the type variable we're inferring for). + */ + function inferTypeForHomomorphicMappedType(source: Type, target: MappedType, constraint: IndexType): Type | undefined { + const cacheKey = source.id + "," + target.id + "," + constraint.id; + if (reverseMappedCache.has(cacheKey)) { + return reverseMappedCache.get(cacheKey); + } + const type = createReverseMappedType(source, target, constraint); + reverseMappedCache.set(cacheKey, type); + return type; + } + + // We consider a type to be partially inferable if it isn't marked non-inferable or if it is + // an object literal type with at least one property of an inferable type. For example, an object + // literal { a: 123, b: x => true } is marked non-inferable because it contains a context sensitive + // arrow function, but is considered partially inferable because property 'a' has an inferable type. + function isPartiallyInferableType(type: Type): boolean { + return !(getObjectFlags(type) & ObjectFlags.NonInferrableType) || + isObjectLiteralType(type) && some(getPropertiesOfType(type), prop => isPartiallyInferableType(getTypeOfSymbol(prop))) || + isTupleType(type) && some(getElementTypes(type), isPartiallyInferableType); + } + + function createReverseMappedType(source: Type, target: MappedType, constraint: IndexType) { + // We consider a source type reverse mappable if it has a string index signature or if + // it has one or more properties and is of a partially inferable type. + if (!(getIndexInfoOfType(source, stringType) || getPropertiesOfType(source).length !== 0 && isPartiallyInferableType(source))) { + return undefined; + } + // For arrays and tuples we infer new arrays and tuples where the reverse mapping has been + // applied to the element type(s). + if (isArrayType(source)) { + const elementType = inferReverseMappedType(getTypeArguments(source)[0], target, constraint); + if (!elementType) { + return undefined; + } + return createArrayType(elementType, isReadonlyArrayType(source)); + } + if (isTupleType(source)) { + const elementTypes = map(getElementTypes(source), t => inferReverseMappedType(t, target, constraint)); + if (!every(elementTypes, (t): t is Type => !!t)) { + return undefined; + } + const elementFlags = getMappedTypeModifiers(target) & MappedTypeModifiers.IncludeOptional ? + sameMap(source.target.elementFlags, f => f & ElementFlags.Optional ? ElementFlags.Required : f) : + source.target.elementFlags; + return createTupleType(elementTypes, elementFlags, source.target.readonly, source.target.labeledElementDeclarations); + } + // For all other object types we infer a new object type where the reverse mapping has been + // applied to the type of each property. + const reversed = createObjectType(ObjectFlags.ReverseMapped | ObjectFlags.Anonymous, /*symbol*/ undefined) as ReverseMappedType; + reversed.source = source; + reversed.mappedType = target; + reversed.constraintType = constraint; + return reversed; + } + + function getTypeOfReverseMappedSymbol(symbol: ReverseMappedSymbol): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + links.type = inferReverseMappedType(symbol.links.propertyType, symbol.links.mappedType, symbol.links.constraintType) || unknownType; + } + return links.type; + } + + function inferReverseMappedTypeWorker(sourceType: Type, target: MappedType, constraint: IndexType): Type { + const typeParameter = getIndexedAccessType(constraint.type, getTypeParameterFromMappedType(target)) as TypeParameter; + const templateType = getTemplateTypeFromMappedType(target); + const inference = createInferenceInfo(typeParameter); + inferTypes([inference], sourceType, templateType); + return getTypeFromInference(inference) || unknownType; + } + + function inferReverseMappedType(source: Type, target: MappedType, constraint: IndexType): Type | undefined { + const cacheKey = source.id + "," + target.id + "," + constraint.id; + if (reverseMappedCache.has(cacheKey)) { + return reverseMappedCache.get(cacheKey) || unknownType; + } + reverseMappedSourceStack.push(source); + reverseMappedTargetStack.push(target); + const saveExpandingFlags = reverseExpandingFlags; + if (isDeeplyNestedType(source, reverseMappedSourceStack, reverseMappedSourceStack.length, 2)) reverseExpandingFlags |= ExpandingFlags.Source; + if (isDeeplyNestedType(target, reverseMappedTargetStack, reverseMappedTargetStack.length, 2)) reverseExpandingFlags |= ExpandingFlags.Target; + let type; + if (reverseExpandingFlags !== ExpandingFlags.Both) { + type = inferReverseMappedTypeWorker(source, target, constraint); + } + reverseMappedSourceStack.pop(); + reverseMappedTargetStack.pop(); + reverseExpandingFlags = saveExpandingFlags; + reverseMappedCache.set(cacheKey, type); + return type; + } + + function* getUnmatchedProperties(source: Type, target: Type, requireOptionalProperties: boolean, matchDiscriminantProperties: boolean): IterableIterator { + const properties = getPropertiesOfType(target); + for (const targetProp of properties) { + // TODO: remove this when we support static private identifier fields and find other solutions to get privateNamesAndStaticFields test to pass + if (isStaticPrivateIdentifierProperty(targetProp)) { + continue; + } + if (requireOptionalProperties || !(targetProp.flags & SymbolFlags.Optional || getCheckFlags(targetProp) & CheckFlags.Partial)) { + const sourceProp = getPropertyOfType(source, targetProp.escapedName); + if (!sourceProp) { + yield targetProp; + } + else if (matchDiscriminantProperties) { + const targetType = getTypeOfSymbol(targetProp); + if (targetType.flags & TypeFlags.Unit) { + const sourceType = getTypeOfSymbol(sourceProp); + if (!(sourceType.flags & TypeFlags.Any || getRegularTypeOfLiteralType(sourceType) === getRegularTypeOfLiteralType(targetType))) { + yield targetProp; + } + } + } + } + } + } + + function getUnmatchedProperty(source: Type, target: Type, requireOptionalProperties: boolean, matchDiscriminantProperties: boolean): Symbol | undefined { + return firstOrUndefinedIterator(getUnmatchedProperties(source, target, requireOptionalProperties, matchDiscriminantProperties)); + } + + function tupleTypesDefinitelyUnrelated(source: TupleTypeReference, target: TupleTypeReference) { + return !(target.target.combinedFlags & ElementFlags.Variadic) && target.target.minLength > source.target.minLength || + !(target.target.combinedFlags & ElementFlags.Variable) && (!!(source.target.combinedFlags & ElementFlags.Variable) || target.target.fixedLength < source.target.fixedLength); + } + + function typesDefinitelyUnrelated(source: Type, target: Type) { + // Two tuple types with incompatible arities are definitely unrelated. + // Two object types that each have a property that is unmatched in the other are definitely unrelated. + return isTupleType(source) && isTupleType(target) ? tupleTypesDefinitelyUnrelated(source, target) : + !!getUnmatchedProperty(source, target, /*requireOptionalProperties*/ false, /*matchDiscriminantProperties*/ true) && + !!getUnmatchedProperty(target, source, /*requireOptionalProperties*/ false, /*matchDiscriminantProperties*/ false); + } + + function getTypeFromInference(inference: InferenceInfo) { + return inference.candidates ? getUnionType(inference.candidates, UnionReduction.Subtype) : + inference.contraCandidates ? getIntersectionType(inference.contraCandidates) : + undefined; + } + + function hasSkipDirectInferenceFlag(node: Node) { + return !!getNodeLinks(node).skipDirectInference; + } + + function isFromInferenceBlockedSource(type: Type) { + return !!(type.symbol && some(type.symbol.declarations, hasSkipDirectInferenceFlag)); + } + + function templateLiteralTypesDefinitelyUnrelated(source: TemplateLiteralType, target: TemplateLiteralType) { + // Two template literal types with diffences in their starting or ending text spans are definitely unrelated. + const sourceStart = source.texts[0]; + const targetStart = target.texts[0]; + const sourceEnd = source.texts[source.texts.length - 1]; + const targetEnd = target.texts[target.texts.length - 1]; + const startLen = Math.min(sourceStart.length, targetStart.length); + const endLen = Math.min(sourceEnd.length, targetEnd.length); + return sourceStart.slice(0, startLen) !== targetStart.slice(0, startLen) || + sourceEnd.slice(sourceEnd.length - endLen) !== targetEnd.slice(targetEnd.length - endLen); + } + + /** + * Tests whether the provided string can be parsed as a number. + * @param s The string to test. + * @param roundTripOnly Indicates the resulting number matches the input when converted back to a string. + */ + function isValidNumberString(s: string, roundTripOnly: boolean): boolean { + if (s === "") return false; + const n = +s; + return isFinite(n) && (!roundTripOnly || "" + n === s); + } + + /** + * @param text a valid bigint string excluding a trailing `n`, but including a possible prefix `-`. Use `isValidBigIntString(text, roundTripOnly)` before calling this function. + */ + function parseBigIntLiteralType(text: string) { + return getBigIntLiteralType(parseValidBigInt(text)); + } + + function isMemberOfStringMapping(source: Type, target: Type): boolean { + if (target.flags & TypeFlags.Any) { + return true; + } + if (target.flags & (TypeFlags.String | TypeFlags.TemplateLiteral)) { + return isTypeAssignableTo(source, target); + } + if (target.flags & TypeFlags.StringMapping) { + // We need to see whether applying the same mappings of the target + // onto the source would produce an identical type *and* that + // it's compatible with the inner-most non-string-mapped type. + // + // The intuition here is that if same mappings don't affect the source at all, + // and the source is compatible with the unmapped target, then they must + // still reside in the same domain. + const mappingStack = []; + while (target.flags & TypeFlags.StringMapping) { + mappingStack.unshift(target.symbol); + target = (target as StringMappingType).type; + } + const mappedSource = reduceLeft(mappingStack, (memo, value) => getStringMappingType(value, memo), source); + return mappedSource === source && isMemberOfStringMapping(source, target); + } + return false; + } + + function isValidTypeForTemplateLiteralPlaceholder(source: Type, target: Type): boolean { + if (target.flags & TypeFlags.Intersection) { + return every((target as IntersectionType).types, t => t === emptyTypeLiteralType || isValidTypeForTemplateLiteralPlaceholder(source, t)); + } + if (target.flags & TypeFlags.String || isTypeAssignableTo(source, target)) { + return true; + } + if (source.flags & TypeFlags.StringLiteral) { + const value = (source as StringLiteralType).value; + return !!(target.flags & TypeFlags.Number && isValidNumberString(value, /*roundTripOnly*/ false) || + target.flags & TypeFlags.BigInt && isValidBigIntString(value, /*roundTripOnly*/ false) || + target.flags & (TypeFlags.BooleanLiteral | TypeFlags.Nullable) && value === (target as IntrinsicType).intrinsicName || + target.flags & TypeFlags.StringMapping && isMemberOfStringMapping(getStringLiteralType(value), target) || + target.flags & TypeFlags.TemplateLiteral && isTypeMatchedByTemplateLiteralType(source, target as TemplateLiteralType)); + } + if (source.flags & TypeFlags.TemplateLiteral) { + const texts = (source as TemplateLiteralType).texts; + return texts.length === 2 && texts[0] === "" && texts[1] === "" && isTypeAssignableTo((source as TemplateLiteralType).types[0], target); + } + return false; + } + + function inferTypesFromTemplateLiteralType(source: Type, target: TemplateLiteralType): Type[] | undefined { + return source.flags & TypeFlags.StringLiteral ? inferFromLiteralPartsToTemplateLiteral([(source as StringLiteralType).value], emptyArray, target) : + source.flags & TypeFlags.TemplateLiteral ? + arraysEqual((source as TemplateLiteralType).texts, target.texts) ? map((source as TemplateLiteralType).types, (s, i) => { + return isTypeAssignableTo(getBaseConstraintOrType(s), getBaseConstraintOrType(target.types[i])) ? s : getStringLikeTypeForType(s); + }) : + inferFromLiteralPartsToTemplateLiteral((source as TemplateLiteralType).texts, (source as TemplateLiteralType).types, target) : + undefined; + } + + function isTypeMatchedByTemplateLiteralType(source: Type, target: TemplateLiteralType): boolean { + const inferences = inferTypesFromTemplateLiteralType(source, target); + return !!inferences && every(inferences, (r, i) => isValidTypeForTemplateLiteralPlaceholder(r, target.types[i])); + } + + function getStringLikeTypeForType(type: Type) { + return type.flags & (TypeFlags.Any | TypeFlags.StringLike) ? type : getTemplateLiteralType(["", ""], [type]); + } + + // This function infers from the text parts and type parts of a source literal to a target template literal. The number + // of text parts is always one more than the number of type parts, and a source string literal is treated as a source + // with one text part and zero type parts. The function returns an array of inferred string or template literal types + // corresponding to the placeholders in the target template literal, or undefined if the source doesn't match the target. + // + // We first check that the starting source text part matches the starting target text part, and that the ending source + // text part ends matches the ending target text part. We then iterate through the remaining target text parts, finding + // a match for each in the source and inferring string or template literal types created from the segments of the source + // that occur between the matches. During this iteration, seg holds the index of the current text part in the sourceTexts + // array and pos holds the current character position in the current text part. + // + // Consider inference from type `<<${string}>.<${number}-${number}>>` to type `<${string}.${string}>`, i.e. + // sourceTexts = ['<<', '>.<', '-', '>>'] + // sourceTypes = [string, number, number] + // target.texts = ['<', '.', '>'] + // We first match '<' in the target to the start of '<<' in the source and '>' in the target to the end of '>>' in + // the source. The first match for the '.' in target occurs at character 1 in the source text part at index 1, and thus + // the first inference is the template literal type `<${string}>`. The remainder of the source makes up the second + // inference, the template literal type `<${number}-${number}>`. + function inferFromLiteralPartsToTemplateLiteral(sourceTexts: readonly string[], sourceTypes: readonly Type[], target: TemplateLiteralType): Type[] | undefined { + const lastSourceIndex = sourceTexts.length - 1; + const sourceStartText = sourceTexts[0]; + const sourceEndText = sourceTexts[lastSourceIndex]; + const targetTexts = target.texts; + const lastTargetIndex = targetTexts.length - 1; + const targetStartText = targetTexts[0]; + const targetEndText = targetTexts[lastTargetIndex]; + if ( + lastSourceIndex === 0 && sourceStartText.length < targetStartText.length + targetEndText.length || + !sourceStartText.startsWith(targetStartText) || !sourceEndText.endsWith(targetEndText) + ) return undefined; + const remainingEndText = sourceEndText.slice(0, sourceEndText.length - targetEndText.length); + const matches: Type[] = []; + let seg = 0; + let pos = targetStartText.length; + for (let i = 1; i < lastTargetIndex; i++) { + const delim = targetTexts[i]; + if (delim.length > 0) { + let s = seg; + let p = pos; + while (true) { + p = getSourceText(s).indexOf(delim, p); + if (p >= 0) break; + s++; + if (s === sourceTexts.length) return undefined; + p = 0; + } + addMatch(s, p); + pos += delim.length; + } + else if (pos < getSourceText(seg).length) { + addMatch(seg, pos + 1); + } + else if (seg < lastSourceIndex) { + addMatch(seg + 1, 0); + } + else { + return undefined; + } + } + addMatch(lastSourceIndex, getSourceText(lastSourceIndex).length); + return matches; + function getSourceText(index: number) { + return index < lastSourceIndex ? sourceTexts[index] : remainingEndText; + } + function addMatch(s: number, p: number) { + const matchType = s === seg ? + getStringLiteralType(getSourceText(s).slice(pos, p)) : + getTemplateLiteralType( + [sourceTexts[seg].slice(pos), ...sourceTexts.slice(seg + 1, s), getSourceText(s).slice(0, p)], + sourceTypes.slice(seg, s), + ); + matches.push(matchType); + seg = s; + pos = p; + } + } + + /** + * @returns `true` if `type` has the shape `[T[0]]` where `T` is `typeParameter` + */ + function isTupleOfSelf(typeParameter: TypeParameter, type: Type) { + return isTupleType(type) && getTupleElementType(type, 0) === getIndexedAccessType(typeParameter, getNumberLiteralType(0)) && !getTypeOfPropertyOfType(type, "1" as __String); + } + + function inferTypes(inferences: InferenceInfo[], originalSource: Type, originalTarget: Type, priority = InferencePriority.None, contravariant = false) { + let bivariant = false; + let propagationType: Type; + let inferencePriority: number = InferencePriority.MaxValue; + let visited: Map; + let sourceStack: Type[]; + let targetStack: Type[]; + let expandingFlags = ExpandingFlags.None; + inferFromTypes(originalSource, originalTarget); + + function inferFromTypes(source: Type, target: Type): void { + if (!couldContainTypeVariables(target) || isNoInferType(target)) { + return; + } + if (source === wildcardType || source === blockedStringType) { + // We are inferring from an 'any' type. We want to infer this type for every type parameter + // referenced in the target type, so we record it as the propagation type and infer from the + // target to itself. Then, as we find candidates we substitute the propagation type. + const savePropagationType = propagationType; + propagationType = source; + inferFromTypes(target, target); + propagationType = savePropagationType; + return; + } + if (source.aliasSymbol && source.aliasSymbol === target.aliasSymbol) { + if (source.aliasTypeArguments) { + // Source and target are types originating in the same generic type alias declaration. + // Simply infer from source type arguments to target type arguments, with defaults applied. + const params = getSymbolLinks(source.aliasSymbol).typeParameters!; + const minParams = getMinTypeArgumentCount(params); + const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + inferFromTypeArguments(sourceTypes, targetTypes!, getAliasVariances(source.aliasSymbol)); + } + // And if there weren't any type arguments, there's no reason to run inference as the types must be the same. + return; + } + if (source === target && source.flags & TypeFlags.UnionOrIntersection) { + // When source and target are the same union or intersection type, just relate each constituent + // type to itself. + for (const t of (source as UnionOrIntersectionType).types) { + inferFromTypes(t, t); + } + return; + } + if (target.flags & TypeFlags.Union) { + // First, infer between identically matching source and target constituents and remove the + // matching types. + const [tempSources, tempTargets] = inferFromMatchingTypes(source.flags & TypeFlags.Union ? (source as UnionType).types : [source], (target as UnionType).types, isTypeOrBaseIdenticalTo); + // Next, infer between closely matching source and target constituents and remove + // the matching types. Types closely match when they are instantiations of the same + // object type or instantiations of the same type alias. + const [sources, targets] = inferFromMatchingTypes(tempSources, tempTargets, isTypeCloselyMatchedBy); + if (targets.length === 0) { + return; + } + target = getUnionType(targets); + if (sources.length === 0) { + // All source constituents have been matched and there is nothing further to infer from. + // However, simply making no inferences is undesirable because it could ultimately mean + // inferring a type parameter constraint. Instead, make a lower priority inference from + // the full source to whatever remains in the target. For example, when inferring from + // string to 'string | T', make a lower priority inference of string for T. + inferWithPriority(source, target, InferencePriority.NakedTypeVariable); + return; + } + source = getUnionType(sources); + } + else if (target.flags & TypeFlags.Intersection && !every((target as IntersectionType).types, isNonGenericObjectType)) { + // We reduce intersection types unless they're simple combinations of object types. For example, + // when inferring from 'string[] & { extra: any }' to 'string[] & T' we want to remove string[] and + // infer { extra: any } for T. But when inferring to 'string[] & Iterable' we want to keep the + // string[] on the source side and infer string for T. + if (!(source.flags & TypeFlags.Union)) { + // Infer between identically matching source and target constituents and remove the matching types. + const [sources, targets] = inferFromMatchingTypes(source.flags & TypeFlags.Intersection ? (source as IntersectionType).types : [source], (target as IntersectionType).types, isTypeIdenticalTo); + if (sources.length === 0 || targets.length === 0) { + return; + } + source = getIntersectionType(sources); + target = getIntersectionType(targets); + } + } + if (target.flags & (TypeFlags.IndexedAccess | TypeFlags.Substitution)) { + if (isNoInferType(target)) { + return; + } + target = getActualTypeVariable(target); + } + if (target.flags & TypeFlags.TypeVariable) { + // Skip inference if the source is "blocked", which is used by the language service to + // prevent inference on nodes currently being edited. + if (isFromInferenceBlockedSource(source)) { + return; + } + const inference = getInferenceInfoForType(target); + if (inference) { + // If target is a type parameter, make an inference, unless the source type contains + // a "non-inferrable" type. Types with this flag set are markers used to prevent inference. + // + // For example: + // - anyFunctionType is a wildcard type that's used to avoid contextually typing functions; + // it's internal, so should not be exposed to the user by adding it as a candidate. + // - autoType (and autoArrayType) is a special "any" used in control flow; like anyFunctionType, + // it's internal and should not be observable. + // - silentNeverType is returned by getInferredType when instantiating a generic function for + // inference (and a type variable has no mapping). + // + // This flag is infectious; if we produce Box (where never is silentNeverType), Box is + // also non-inferrable. + // + // As a special case, also ignore nonInferrableAnyType, which is a special form of the any type + // used as a stand-in for binding elements when they are being inferred. + if (getObjectFlags(source) & ObjectFlags.NonInferrableType || source === nonInferrableAnyType) { + return; + } + if (!inference.isFixed) { + const candidate = propagationType || source; + if (candidate === blockedStringType) { + return; + } + if (inference.priority === undefined || priority < inference.priority) { + inference.candidates = undefined; + inference.contraCandidates = undefined; + inference.topLevel = true; + inference.priority = priority; + } + if (priority === inference.priority) { + // Inferring A to [A[0]] is a zero information inference (it guarantees A becomes its constraint), but oft arises from generic argument list inferences + // By discarding it early, we can allow more fruitful results to be used instead. + if (isTupleOfSelf(inference.typeParameter, candidate)) { + return; + } + // We make contravariant inferences only if we are in a pure contravariant position, + // i.e. only if we have not descended into a bivariant position. + if (contravariant && !bivariant) { + if (!contains(inference.contraCandidates, candidate)) { + inference.contraCandidates = append(inference.contraCandidates, candidate); + clearCachedInferences(inferences); + } + } + else if (!contains(inference.candidates, candidate)) { + inference.candidates = append(inference.candidates, candidate); + clearCachedInferences(inferences); + } + } + if (!(priority & InferencePriority.ReturnType) && target.flags & TypeFlags.TypeParameter && inference.topLevel && !isTypeParameterAtTopLevel(originalTarget, target as TypeParameter)) { + inference.topLevel = false; + clearCachedInferences(inferences); + } + } + inferencePriority = Math.min(inferencePriority, priority); + return; + } + // Infer to the simplified version of an indexed access, if possible, to (hopefully) expose more bare type parameters to the inference engine + const simplified = getSimplifiedType(target, /*writing*/ false); + if (simplified !== target) { + inferFromTypes(source, simplified); + } + else if (target.flags & TypeFlags.IndexedAccess) { + const indexType = getSimplifiedType((target as IndexedAccessType).indexType, /*writing*/ false); + // Generally simplifications of instantiable indexes are avoided to keep relationship checking correct, however if our target is an access, we can consider + // that key of that access to be "instantiated", since we're looking to find the infernce goal in any way we can. + if (indexType.flags & TypeFlags.Instantiable) { + const simplified = distributeIndexOverObjectType(getSimplifiedType((target as IndexedAccessType).objectType, /*writing*/ false), indexType, /*writing*/ false); + if (simplified && simplified !== target) { + inferFromTypes(source, simplified); + } + } + } + } + if ( + getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && ( + (source as TypeReference).target === (target as TypeReference).target || isArrayType(source) && isArrayType(target) + ) && + !((source as TypeReference).node && (target as TypeReference).node) + ) { + // If source and target are references to the same generic type, infer from type arguments + inferFromTypeArguments(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), getVariances((source as TypeReference).target)); + } + else if (source.flags & TypeFlags.Index && target.flags & TypeFlags.Index) { + inferFromContravariantTypes((source as IndexType).type, (target as IndexType).type); + } + else if ((isLiteralType(source) || source.flags & TypeFlags.String) && target.flags & TypeFlags.Index) { + const empty = createEmptyObjectTypeFromStringLiteral(source); + inferFromContravariantTypesWithPriority(empty, (target as IndexType).type, InferencePriority.LiteralKeyof); + } + else if (source.flags & TypeFlags.IndexedAccess && target.flags & TypeFlags.IndexedAccess) { + inferFromTypes((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType); + inferFromTypes((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType); + } + else if (source.flags & TypeFlags.StringMapping && target.flags & TypeFlags.StringMapping) { + if ((source as StringMappingType).symbol === (target as StringMappingType).symbol) { + inferFromTypes((source as StringMappingType).type, (target as StringMappingType).type); + } + } + else if (source.flags & TypeFlags.Substitution) { + inferFromTypes((source as SubstitutionType).baseType, target); + inferWithPriority(getSubstitutionIntersection(source as SubstitutionType), target, InferencePriority.SubstituteSource); // Make substitute inference at a lower priority + } + else if (target.flags & TypeFlags.Conditional) { + invokeOnce(source, target as ConditionalType, inferToConditionalType); + } + else if (target.flags & TypeFlags.UnionOrIntersection) { + inferToMultipleTypes(source, (target as UnionOrIntersectionType).types, target.flags); + } + else if (source.flags & TypeFlags.Union) { + // Source is a union or intersection type, infer from each constituent type + const sourceTypes = (source as UnionOrIntersectionType).types; + for (const sourceType of sourceTypes) { + inferFromTypes(sourceType, target); + } + } + else if (target.flags & TypeFlags.TemplateLiteral) { + inferToTemplateLiteralType(source, target as TemplateLiteralType); + } + else { + source = getReducedType(source); + if (isGenericMappedType(source) && isGenericMappedType(target)) { + invokeOnce(source, target, inferFromGenericMappedTypes); + } + if (!(priority & InferencePriority.NoConstraints && source.flags & (TypeFlags.Intersection | TypeFlags.Instantiable))) { + const apparentSource = getApparentType(source); + // getApparentType can return _any_ type, since an indexed access or conditional may simplify to any other type. + // If that occurs and it doesn't simplify to an object or intersection, we'll need to restart `inferFromTypes` + // with the simplified source. + if (apparentSource !== source && !(apparentSource.flags & (TypeFlags.Object | TypeFlags.Intersection))) { + return inferFromTypes(apparentSource, target); + } + source = apparentSource; + } + if (source.flags & (TypeFlags.Object | TypeFlags.Intersection)) { + invokeOnce(source, target, inferFromObjectTypes); + } + } + } + + function inferWithPriority(source: Type, target: Type, newPriority: InferencePriority) { + const savePriority = priority; + priority |= newPriority; + inferFromTypes(source, target); + priority = savePriority; + } + + function inferFromContravariantTypesWithPriority(source: Type, target: Type, newPriority: InferencePriority) { + const savePriority = priority; + priority |= newPriority; + inferFromContravariantTypes(source, target); + priority = savePriority; + } + + function inferToMultipleTypesWithPriority(source: Type, targets: Type[], targetFlags: TypeFlags, newPriority: InferencePriority) { + const savePriority = priority; + priority |= newPriority; + inferToMultipleTypes(source, targets, targetFlags); + priority = savePriority; + } + + // Ensure an inference action is performed only once for the given source and target types. + // This includes two things: + // Avoiding inferring between the same pair of source and target types, + // and avoiding circularly inferring between source and target types. + // For an example of the last, consider if we are inferring between source type + // `type Deep = { next: Deep> }` and target type `type Loop = { next: Loop }`. + // We would then infer between the types of the `next` property: `Deep>` = `{ next: Deep>> }` and `Loop` = `{ next: Loop }`. + // We will then infer again between the types of the `next` property: + // `Deep>>` and `Loop`, and so on, such that we would be forever inferring + // between instantiations of the same types `Deep` and `Loop`. + // In particular, we would be inferring from increasingly deep instantiations of `Deep` to `Loop`, + // such that we would go on inferring forever, even though we would never infer + // between the same pair of types. + function invokeOnce(source: Source, target: Target, action: (source: Source, target: Target) => void) { + const key = source.id + "," + target.id; + const status = visited && visited.get(key); + if (status !== undefined) { + inferencePriority = Math.min(inferencePriority, status); + return; + } + (visited || (visited = new Map())).set(key, InferencePriority.Circularity); + const saveInferencePriority = inferencePriority; + inferencePriority = InferencePriority.MaxValue; + // We stop inferring and report a circularity if we encounter duplicate recursion identities on both + // the source side and the target side. + const saveExpandingFlags = expandingFlags; + (sourceStack ??= []).push(source); + (targetStack ??= []).push(target); + if (isDeeplyNestedType(source, sourceStack, sourceStack.length, 2)) expandingFlags |= ExpandingFlags.Source; + if (isDeeplyNestedType(target, targetStack, targetStack.length, 2)) expandingFlags |= ExpandingFlags.Target; + if (expandingFlags !== ExpandingFlags.Both) { + action(source, target); + } + else { + inferencePriority = InferencePriority.Circularity; + } + targetStack.pop(); + sourceStack.pop(); + expandingFlags = saveExpandingFlags; + visited.set(key, inferencePriority); + inferencePriority = Math.min(inferencePriority, saveInferencePriority); + } + + function inferFromMatchingTypes(sources: Type[], targets: Type[], matches: (s: Type, t: Type) => boolean): [Type[], Type[]] { + let matchedSources: Type[] | undefined; + let matchedTargets: Type[] | undefined; + for (const t of targets) { + for (const s of sources) { + if (matches(s, t)) { + inferFromTypes(s, t); + matchedSources = appendIfUnique(matchedSources, s); + matchedTargets = appendIfUnique(matchedTargets, t); + } + } + } + return [ + matchedSources ? filter(sources, t => !contains(matchedSources, t)) : sources, + matchedTargets ? filter(targets, t => !contains(matchedTargets, t)) : targets, + ]; + } + + function inferFromTypeArguments(sourceTypes: readonly Type[], targetTypes: readonly Type[], variances: readonly VarianceFlags[]) { + const count = sourceTypes.length < targetTypes.length ? sourceTypes.length : targetTypes.length; + for (let i = 0; i < count; i++) { + if (i < variances.length && (variances[i] & VarianceFlags.VarianceMask) === VarianceFlags.Contravariant) { + inferFromContravariantTypes(sourceTypes[i], targetTypes[i]); + } + else { + inferFromTypes(sourceTypes[i], targetTypes[i]); + } + } + } + + function inferFromContravariantTypes(source: Type, target: Type) { + contravariant = !contravariant; + inferFromTypes(source, target); + contravariant = !contravariant; + } + + function inferFromContravariantTypesIfStrictFunctionTypes(source: Type, target: Type) { + if (strictFunctionTypes || priority & InferencePriority.AlwaysStrict) { + inferFromContravariantTypes(source, target); + } + else { + inferFromTypes(source, target); + } + } + + function getInferenceInfoForType(type: Type) { + if (type.flags & TypeFlags.TypeVariable) { + for (const inference of inferences) { + if (type === inference.typeParameter) { + return inference; + } + } + } + return undefined; + } + + function getSingleTypeVariableFromIntersectionTypes(types: Type[]) { + let typeVariable: Type | undefined; + for (const type of types) { + const t = type.flags & TypeFlags.Intersection && find((type as IntersectionType).types, t => !!getInferenceInfoForType(t)); + if (!t || typeVariable && t !== typeVariable) { + return undefined; + } + typeVariable = t; + } + return typeVariable; + } + + function inferToMultipleTypes(source: Type, targets: Type[], targetFlags: TypeFlags) { + let typeVariableCount = 0; + if (targetFlags & TypeFlags.Union) { + let nakedTypeVariable: Type | undefined; + const sources = source.flags & TypeFlags.Union ? (source as UnionType).types : [source]; + const matched = new Array(sources.length); + let inferenceCircularity = false; + // First infer to types that are not naked type variables. For each source type we + // track whether inferences were made from that particular type to some target with + // equal priority (i.e. of equal quality) to what we would infer for a naked type + // parameter. + for (const t of targets) { + if (getInferenceInfoForType(t)) { + nakedTypeVariable = t; + typeVariableCount++; + } + else { + for (let i = 0; i < sources.length; i++) { + const saveInferencePriority = inferencePriority; + inferencePriority = InferencePriority.MaxValue; + inferFromTypes(sources[i], t); + if (inferencePriority === priority) matched[i] = true; + inferenceCircularity = inferenceCircularity || inferencePriority === InferencePriority.Circularity; + inferencePriority = Math.min(inferencePriority, saveInferencePriority); + } + } + } + if (typeVariableCount === 0) { + // If every target is an intersection of types containing a single naked type variable, + // make a lower priority inference to that type variable. This handles inferring from + // 'A | B' to 'T & (X | Y)' where we want to infer 'A | B' for T. + const intersectionTypeVariable = getSingleTypeVariableFromIntersectionTypes(targets); + if (intersectionTypeVariable) { + inferWithPriority(source, intersectionTypeVariable, InferencePriority.NakedTypeVariable); + } + return; + } + // If the target has a single naked type variable and no inference circularities were + // encountered above (meaning we explored the types fully), create a union of the source + // types from which no inferences have been made so far and infer from that union to the + // naked type variable. + if (typeVariableCount === 1 && !inferenceCircularity) { + const unmatched = flatMap(sources, (s, i) => matched[i] ? undefined : s); + if (unmatched.length) { + inferFromTypes(getUnionType(unmatched), nakedTypeVariable!); + return; + } + } + } + else { + // We infer from types that are not naked type variables first so that inferences we + // make from nested naked type variables and given slightly higher priority by virtue + // of being first in the candidates array. + for (const t of targets) { + if (getInferenceInfoForType(t)) { + typeVariableCount++; + } + else { + inferFromTypes(source, t); + } + } + } + // Inferences directly to naked type variables are given lower priority as they are + // less specific. For example, when inferring from Promise to T | Promise, + // we want to infer string for T, not Promise | string. For intersection types + // we only infer to single naked type variables. + if (targetFlags & TypeFlags.Intersection ? typeVariableCount === 1 : typeVariableCount > 0) { + for (const t of targets) { + if (getInferenceInfoForType(t)) { + inferWithPriority(source, t, InferencePriority.NakedTypeVariable); + } + } + } + } + + function inferToMappedType(source: Type, target: MappedType, constraintType: Type): boolean { + if ((constraintType.flags & TypeFlags.Union) || (constraintType.flags & TypeFlags.Intersection)) { + let result = false; + for (const type of (constraintType as (UnionType | IntersectionType)).types) { + result = inferToMappedType(source, target, type) || result; + } + return result; + } + if (constraintType.flags & TypeFlags.Index) { + // We're inferring from some source type S to a homomorphic mapped type { [P in keyof T]: X }, + // where T is a type variable. Use inferTypeForHomomorphicMappedType to infer a suitable source + // type and then make a secondary inference from that type to T. We make a secondary inference + // such that direct inferences to T get priority over inferences to Partial, for example. + const inference = getInferenceInfoForType((constraintType as IndexType).type); + if (inference && !inference.isFixed && !isFromInferenceBlockedSource(source)) { + const inferredType = inferTypeForHomomorphicMappedType(source, target, constraintType as IndexType); + if (inferredType) { + // We assign a lower priority to inferences made from types containing non-inferrable + // types because we may only have a partial result (i.e. we may have failed to make + // reverse inferences for some properties). + inferWithPriority( + inferredType, + inference.typeParameter, + getObjectFlags(source) & ObjectFlags.NonInferrableType ? + InferencePriority.PartialHomomorphicMappedType : + InferencePriority.HomomorphicMappedType, + ); + } + } + return true; + } + if (constraintType.flags & TypeFlags.TypeParameter) { + // We're inferring from some source type S to a mapped type { [P in K]: X }, where K is a type + // parameter. First infer from 'keyof S' to K. + inferWithPriority(getIndexType(source, /*indexFlags*/ !!source.pattern ? IndexFlags.NoIndexSignatures : IndexFlags.None), constraintType, InferencePriority.MappedTypeConstraint); + // If K is constrained to a type C, also infer to C. Thus, for a mapped type { [P in K]: X }, + // where K extends keyof T, we make the same inferences as for a homomorphic mapped type + // { [P in keyof T]: X }. This enables us to make meaningful inferences when the target is a + // Pick. + const extendedConstraint = getConstraintOfType(constraintType); + if (extendedConstraint && inferToMappedType(source, target, extendedConstraint)) { + return true; + } + // If no inferences can be made to K's constraint, infer from a union of the property types + // in the source to the template type X. + const propTypes = map(getPropertiesOfType(source), getTypeOfSymbol); + const indexTypes = map(getIndexInfosOfType(source), info => info !== enumNumberIndexInfo ? info.type : neverType); + inferFromTypes(getUnionType(concatenate(propTypes, indexTypes)), getTemplateTypeFromMappedType(target)); + return true; + } + return false; + } + + function inferToConditionalType(source: Type, target: ConditionalType) { + if (source.flags & TypeFlags.Conditional) { + inferFromTypes((source as ConditionalType).checkType, target.checkType); + inferFromTypes((source as ConditionalType).extendsType, target.extendsType); + inferFromTypes(getTrueTypeFromConditionalType(source as ConditionalType), getTrueTypeFromConditionalType(target)); + inferFromTypes(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target)); + } + else { + const targetTypes = [getTrueTypeFromConditionalType(target), getFalseTypeFromConditionalType(target)]; + inferToMultipleTypesWithPriority(source, targetTypes, target.flags, contravariant ? InferencePriority.ContravariantConditional : 0); + } + } + + function inferToTemplateLiteralType(source: Type, target: TemplateLiteralType) { + const matches = inferTypesFromTemplateLiteralType(source, target); + const types = target.types; + // When the target template literal contains only placeholders (meaning that inference is intended to extract + // single characters and remainder strings) and inference fails to produce matches, we want to infer 'never' for + // each placeholder such that instantiation with the inferred value(s) produces 'never', a type for which an + // assignment check will fail. If we make no inferences, we'll likely end up with the constraint 'string' which, + // upon instantiation, would collapse all the placeholders to just 'string', and an assignment check might + // succeed. That would be a pointless and confusing outcome. + if (matches || every(target.texts, s => s.length === 0)) { + for (let i = 0; i < types.length; i++) { + const source = matches ? matches[i] : neverType; + const target = types[i]; + + // If we are inferring from a string literal type to a type variable whose constraint includes one of the + // allowed template literal placeholder types, infer from a literal type corresponding to the constraint. + if (source.flags & TypeFlags.StringLiteral && target.flags & TypeFlags.TypeVariable) { + const inferenceContext = getInferenceInfoForType(target); + const constraint = inferenceContext ? getBaseConstraintOfType(inferenceContext.typeParameter) : undefined; + if (constraint && !isTypeAny(constraint)) { + const constraintTypes = constraint.flags & TypeFlags.Union ? (constraint as UnionType).types : [constraint]; + let allTypeFlags: TypeFlags = reduceLeft(constraintTypes, (flags, t) => flags | t.flags, 0 as TypeFlags); + + // If the constraint contains `string`, we don't need to look for a more preferred type + if (!(allTypeFlags & TypeFlags.String)) { + const str = (source as StringLiteralType).value; + + // If the type contains `number` or a number literal and the string isn't a valid number, exclude numbers + if (allTypeFlags & TypeFlags.NumberLike && !isValidNumberString(str, /*roundTripOnly*/ true)) { + allTypeFlags &= ~TypeFlags.NumberLike; + } + + // If the type contains `bigint` or a bigint literal and the string isn't a valid bigint, exclude bigints + if (allTypeFlags & TypeFlags.BigIntLike && !isValidBigIntString(str, /*roundTripOnly*/ true)) { + allTypeFlags &= ~TypeFlags.BigIntLike; + } + + // for each type in the constraint, find the highest priority matching type + const matchingType = reduceLeft(constraintTypes, (left, right) => + !(right.flags & allTypeFlags) ? left : + left.flags & TypeFlags.String ? left : right.flags & TypeFlags.String ? source : + left.flags & TypeFlags.TemplateLiteral ? left : right.flags & TypeFlags.TemplateLiteral && isTypeMatchedByTemplateLiteralType(source, right as TemplateLiteralType) ? source : + left.flags & TypeFlags.StringMapping ? left : right.flags & TypeFlags.StringMapping && str === applyStringMapping(right.symbol, str) ? source : + left.flags & TypeFlags.StringLiteral ? left : right.flags & TypeFlags.StringLiteral && (right as StringLiteralType).value === str ? right : + left.flags & TypeFlags.Number ? left : right.flags & TypeFlags.Number ? getNumberLiteralType(+str) : + left.flags & TypeFlags.Enum ? left : right.flags & TypeFlags.Enum ? getNumberLiteralType(+str) : + left.flags & TypeFlags.NumberLiteral ? left : right.flags & TypeFlags.NumberLiteral && (right as NumberLiteralType).value === +str ? right : + left.flags & TypeFlags.BigInt ? left : right.flags & TypeFlags.BigInt ? parseBigIntLiteralType(str) : + left.flags & TypeFlags.BigIntLiteral ? left : right.flags & TypeFlags.BigIntLiteral && pseudoBigIntToString((right as BigIntLiteralType).value) === str ? right : + left.flags & TypeFlags.Boolean ? left : right.flags & TypeFlags.Boolean ? str === "true" ? trueType : str === "false" ? falseType : booleanType : + left.flags & TypeFlags.BooleanLiteral ? left : right.flags & TypeFlags.BooleanLiteral && (right as IntrinsicType).intrinsicName === str ? right : + left.flags & TypeFlags.Undefined ? left : right.flags & TypeFlags.Undefined && (right as IntrinsicType).intrinsicName === str ? right : + left.flags & TypeFlags.Null ? left : right.flags & TypeFlags.Null && (right as IntrinsicType).intrinsicName === str ? right : + left, neverType as Type); + + if (!(matchingType.flags & TypeFlags.Never)) { + inferFromTypes(matchingType, target); + continue; + } + } + } + } + + inferFromTypes(source, target); + } + } + } + + function inferFromGenericMappedTypes(source: MappedType, target: MappedType) { + // The source and target types are generic types { [P in S]: X } and { [P in T]: Y }, so we infer + // from S to T and from X to Y. + inferFromTypes(getConstraintTypeFromMappedType(source), getConstraintTypeFromMappedType(target)); + inferFromTypes(getTemplateTypeFromMappedType(source), getTemplateTypeFromMappedType(target)); + const sourceNameType = getNameTypeFromMappedType(source); + const targetNameType = getNameTypeFromMappedType(target); + if (sourceNameType && targetNameType) inferFromTypes(sourceNameType, targetNameType); + } + + function inferFromObjectTypes(source: Type, target: Type) { + if ( + getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && ( + (source as TypeReference).target === (target as TypeReference).target || isArrayType(source) && isArrayType(target) + ) + ) { + // If source and target are references to the same generic type, infer from type arguments + inferFromTypeArguments(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), getVariances((source as TypeReference).target)); + return; + } + if (isGenericMappedType(source) && isGenericMappedType(target)) { + inferFromGenericMappedTypes(source, target); + } + if (getObjectFlags(target) & ObjectFlags.Mapped && !(target as MappedType).declaration.nameType) { + const constraintType = getConstraintTypeFromMappedType(target as MappedType); + if (inferToMappedType(source, target as MappedType, constraintType)) { + return; + } + } + // Infer from the members of source and target only if the two types are possibly related + if (!typesDefinitelyUnrelated(source, target)) { + if (isArrayOrTupleType(source)) { + if (isTupleType(target)) { + const sourceArity = getTypeReferenceArity(source); + const targetArity = getTypeReferenceArity(target); + const elementTypes = getTypeArguments(target); + const elementFlags = target.target.elementFlags; + // When source and target are tuple types with the same structure (fixed, variadic, and rest are matched + // to the same kind in each position), simply infer between the element types. + if (isTupleType(source) && isTupleTypeStructureMatching(source, target)) { + for (let i = 0; i < targetArity; i++) { + inferFromTypes(getTypeArguments(source)[i], elementTypes[i]); + } + return; + } + const startLength = isTupleType(source) ? Math.min(source.target.fixedLength, target.target.fixedLength) : 0; + const endLength = Math.min(isTupleType(source) ? getEndElementCount(source.target, ElementFlags.Fixed) : 0, target.target.combinedFlags & ElementFlags.Variable ? getEndElementCount(target.target, ElementFlags.Fixed) : 0); + // Infer between starting fixed elements. + for (let i = 0; i < startLength; i++) { + inferFromTypes(getTypeArguments(source)[i], elementTypes[i]); + } + if (!isTupleType(source) || sourceArity - startLength - endLength === 1 && source.target.elementFlags[startLength] & ElementFlags.Rest) { + // Single rest element remains in source, infer from that to every element in target + const restType = getTypeArguments(source)[startLength]; + for (let i = startLength; i < targetArity - endLength; i++) { + inferFromTypes(elementFlags[i] & ElementFlags.Variadic ? createArrayType(restType) : restType, elementTypes[i]); + } + } + else { + const middleLength = targetArity - startLength - endLength; + if (middleLength === 2) { + if (elementFlags[startLength] & elementFlags[startLength + 1] & ElementFlags.Variadic) { + // Middle of target is [...T, ...U] and source is tuple type + const targetInfo = getInferenceInfoForType(elementTypes[startLength]); + if (targetInfo && targetInfo.impliedArity !== undefined) { + // Infer slices from source based on implied arity of T. + inferFromTypes(sliceTupleType(source, startLength, endLength + sourceArity - targetInfo.impliedArity), elementTypes[startLength]); + inferFromTypes(sliceTupleType(source, startLength + targetInfo.impliedArity, endLength), elementTypes[startLength + 1]); + } + } + else if (elementFlags[startLength] & ElementFlags.Variadic && elementFlags[startLength + 1] & ElementFlags.Rest) { + // Middle of target is [...T, ...rest] and source is tuple type + // if T is constrained by a fixed-size tuple we might be able to use its arity to infer T + const param = getInferenceInfoForType(elementTypes[startLength])?.typeParameter; + const constraint = param && getBaseConstraintOfType(param); + if (constraint && isTupleType(constraint) && !(constraint.target.combinedFlags & ElementFlags.Variable)) { + const impliedArity = constraint.target.fixedLength; + inferFromTypes(sliceTupleType(source, startLength, sourceArity - (startLength + impliedArity)), elementTypes[startLength]); + inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength + impliedArity, endLength)!, elementTypes[startLength + 1]); + } + } + else if (elementFlags[startLength] & ElementFlags.Rest && elementFlags[startLength + 1] & ElementFlags.Variadic) { + // Middle of target is [...rest, ...T] and source is tuple type + // if T is constrained by a fixed-size tuple we might be able to use its arity to infer T + const param = getInferenceInfoForType(elementTypes[startLength + 1])?.typeParameter; + const constraint = param && getBaseConstraintOfType(param); + if (constraint && isTupleType(constraint) && !(constraint.target.combinedFlags & ElementFlags.Variable)) { + const impliedArity = constraint.target.fixedLength; + const endIndex = sourceArity - getEndElementCount(target.target, ElementFlags.Fixed); + const startIndex = endIndex - impliedArity; + const trailingSlice = createTupleType(getTypeArguments(source).slice(startIndex, endIndex), source.target.elementFlags.slice(startIndex, endIndex), /*readonly*/ false, source.target.labeledElementDeclarations && source.target.labeledElementDeclarations.slice(startIndex, endIndex)); + + inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength, endLength + impliedArity)!, elementTypes[startLength]); + inferFromTypes(trailingSlice, elementTypes[startLength + 1]); + } + } + } + else if (middleLength === 1 && elementFlags[startLength] & ElementFlags.Variadic) { + // Middle of target is exactly one variadic element. Infer the slice between the fixed parts in the source. + // If target ends in optional element(s), make a lower priority a speculative inference. + const endsInOptional = target.target.elementFlags[targetArity - 1] & ElementFlags.Optional; + const sourceSlice = sliceTupleType(source, startLength, endLength); + inferWithPriority(sourceSlice, elementTypes[startLength], endsInOptional ? InferencePriority.SpeculativeTuple : 0); + } + else if (middleLength === 1 && elementFlags[startLength] & ElementFlags.Rest) { + // Middle of target is exactly one rest element. If middle of source is not empty, infer union of middle element types. + const restType = getElementTypeOfSliceOfTupleType(source, startLength, endLength); + if (restType) { + inferFromTypes(restType, elementTypes[startLength]); + } + } + } + // Infer between ending fixed elements + for (let i = 0; i < endLength; i++) { + inferFromTypes(getTypeArguments(source)[sourceArity - i - 1], elementTypes[targetArity - i - 1]); + } + return; + } + if (isArrayType(target)) { + inferFromIndexTypes(source, target); + return; + } + } + inferFromProperties(source, target); + inferFromSignatures(source, target, SignatureKind.Call); + inferFromSignatures(source, target, SignatureKind.Construct); + inferFromIndexTypes(source, target); + } + } + + function inferFromProperties(source: Type, target: Type) { + const properties = getPropertiesOfObjectType(target); + for (const targetProp of properties) { + const sourceProp = getPropertyOfType(source, targetProp.escapedName); + if (sourceProp && !some(sourceProp.declarations, hasSkipDirectInferenceFlag)) { + inferFromTypes( + removeMissingType(getTypeOfSymbol(sourceProp), !!(sourceProp.flags & SymbolFlags.Optional)), + removeMissingType(getTypeOfSymbol(targetProp), !!(targetProp.flags & SymbolFlags.Optional)), + ); + } + } + } + + function inferFromSignatures(source: Type, target: Type, kind: SignatureKind) { + const sourceSignatures = getSignaturesOfType(source, kind); + const sourceLen = sourceSignatures.length; + if (sourceLen > 0) { + // We match source and target signatures from the bottom up, and if the source has fewer signatures + // than the target, we infer from the first source signature to the excess target signatures. + const targetSignatures = getSignaturesOfType(target, kind); + const targetLen = targetSignatures.length; + for (let i = 0; i < targetLen; i++) { + const sourceIndex = Math.max(sourceLen - targetLen + i, 0); + inferFromSignature(getBaseSignature(sourceSignatures[sourceIndex]), getErasedSignature(targetSignatures[i])); + } + } + } + + function inferFromSignature(source: Signature, target: Signature) { + if (!(source.flags & SignatureFlags.IsNonInferrable)) { + const saveBivariant = bivariant; + const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown; + // Once we descend into a bivariant signature we remain bivariant for all nested inferences + bivariant = bivariant || kind === SyntaxKind.MethodDeclaration || kind === SyntaxKind.MethodSignature || kind === SyntaxKind.Constructor; + applyToParameterTypes(source, target, inferFromContravariantTypesIfStrictFunctionTypes); + bivariant = saveBivariant; + } + applyToReturnTypes(source, target, inferFromTypes); + } + + function inferFromIndexTypes(source: Type, target: Type) { + // Inferences across mapped type index signatures are pretty much the same a inferences to homomorphic variables + const priority = (getObjectFlags(source) & getObjectFlags(target) & ObjectFlags.Mapped) ? InferencePriority.HomomorphicMappedType : 0; + const indexInfos = getIndexInfosOfType(target); + if (isObjectTypeWithInferableIndex(source)) { + for (const targetInfo of indexInfos) { + const propTypes: Type[] = []; + for (const prop of getPropertiesOfType(source)) { + if (isApplicableIndexType(getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique), targetInfo.keyType)) { + const propType = getTypeOfSymbol(prop); + propTypes.push(prop.flags & SymbolFlags.Optional ? removeMissingOrUndefinedType(propType) : propType); + } + } + for (const info of getIndexInfosOfType(source)) { + if (isApplicableIndexType(info.keyType, targetInfo.keyType)) { + propTypes.push(info.type); + } + } + if (propTypes.length) { + inferWithPriority(getUnionType(propTypes), targetInfo.type, priority); + } + } + } + for (const targetInfo of indexInfos) { + const sourceInfo = getApplicableIndexInfo(source, targetInfo.keyType); + if (sourceInfo) { + inferWithPriority(sourceInfo.type, targetInfo.type, priority); + } + } + } + } + + function isTypeOrBaseIdenticalTo(s: Type, t: Type) { + return t === missingType ? s === t : + (isTypeIdenticalTo(s, t) || !!(t.flags & TypeFlags.String && s.flags & TypeFlags.StringLiteral || t.flags & TypeFlags.Number && s.flags & TypeFlags.NumberLiteral)); + } + + function isTypeCloselyMatchedBy(s: Type, t: Type) { + return !!(s.flags & TypeFlags.Object && t.flags & TypeFlags.Object && s.symbol && s.symbol === t.symbol || + s.aliasSymbol && s.aliasTypeArguments && s.aliasSymbol === t.aliasSymbol); + } + + function hasPrimitiveConstraint(type: TypeParameter): boolean { + const constraint = getConstraintOfTypeParameter(type); + return !!constraint && maybeTypeOfKind(constraint.flags & TypeFlags.Conditional ? getDefaultConstraintOfConditionalType(constraint as ConditionalType) : constraint, TypeFlags.Primitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping); + } + + function isObjectLiteralType(type: Type) { + return !!(getObjectFlags(type) & ObjectFlags.ObjectLiteral); + } + + function isObjectOrArrayLiteralType(type: Type) { + return !!(getObjectFlags(type) & (ObjectFlags.ObjectLiteral | ObjectFlags.ArrayLiteral)); + } + + function unionObjectAndArrayLiteralCandidates(candidates: Type[]): Type[] { + if (candidates.length > 1) { + const objectLiterals = filter(candidates, isObjectOrArrayLiteralType); + if (objectLiterals.length) { + const literalsType = getUnionType(objectLiterals, UnionReduction.Subtype); + return concatenate(filter(candidates, t => !isObjectOrArrayLiteralType(t)), [literalsType]); + } + } + return candidates; + } + + function getContravariantInference(inference: InferenceInfo) { + return inference.priority! & InferencePriority.PriorityImpliesCombination ? getIntersectionType(inference.contraCandidates!) : getCommonSubtype(inference.contraCandidates!); + } + + function getCovariantInference(inference: InferenceInfo, signature: Signature) { + // Extract all object and array literal types and replace them with a single widened and normalized type. + const candidates = unionObjectAndArrayLiteralCandidates(inference.candidates!); + // We widen inferred literal types if + // all inferences were made to top-level occurrences of the type parameter, and + // the type parameter has no constraint or its constraint includes no primitive or literal types, and + // the type parameter was fixed during inference or does not occur at top-level in the return type. + const primitiveConstraint = hasPrimitiveConstraint(inference.typeParameter) || isConstTypeVariable(inference.typeParameter); + const widenLiteralTypes = !primitiveConstraint && inference.topLevel && + (inference.isFixed || !isTypeParameterAtTopLevelInReturnType(signature, inference.typeParameter)); + const baseCandidates = primitiveConstraint ? sameMap(candidates, getRegularTypeOfLiteralType) : + widenLiteralTypes ? sameMap(candidates, getWidenedLiteralType) : + candidates; + // If all inferences were made from a position that implies a combined result, infer a union type. + // Otherwise, infer a common supertype. + const unwidenedType = inference.priority! & InferencePriority.PriorityImpliesCombination ? + getUnionType(baseCandidates, UnionReduction.Subtype) : + getCommonSupertype(baseCandidates); + return getWidenedType(unwidenedType); + } + + function getInferredType(context: InferenceContext, index: number): Type { + const inference = context.inferences[index]; + if (!inference.inferredType) { + let inferredType: Type | undefined; + let fallbackType: Type | undefined; + if (context.signature) { + const inferredCovariantType = inference.candidates ? getCovariantInference(inference, context.signature) : undefined; + const inferredContravariantType = inference.contraCandidates ? getContravariantInference(inference) : undefined; + if (inferredCovariantType || inferredContravariantType) { + // If we have both co- and contra-variant inferences, we prefer the co-variant inference if it is not 'never', + // all co-variant inferences are assignable to it (i.e. it isn't one of a conflicting set of candidates), it is + // assignable to some contra-variant inference, and no other type parameter is constrained to this type parameter + // and has inferences that would conflict. Otherwise, we prefer the contra-variant inference. + // Similarly ignore co-variant `any` inference when both are available as almost everything is assignable to it + // and it would spoil the overall inference. + const preferCovariantType = inferredCovariantType && (!inferredContravariantType || + !(inferredCovariantType.flags & (TypeFlags.Never | TypeFlags.Any)) && + some(inference.contraCandidates, t => isTypeAssignableTo(inferredCovariantType, t)) && + every(context.inferences, other => + other !== inference && getConstraintOfTypeParameter(other.typeParameter) !== inference.typeParameter || + every(other.candidates, t => isTypeAssignableTo(t, inferredCovariantType)))); + inferredType = preferCovariantType ? inferredCovariantType : inferredContravariantType; + fallbackType = preferCovariantType ? inferredContravariantType : inferredCovariantType; + } + else if (context.flags & InferenceFlags.NoDefault) { + // We use silentNeverType as the wildcard that signals no inferences. + inferredType = silentNeverType; + } + else { + // Infer either the default or the empty object type when no inferences were + // made. It is important to remember that in this case, inference still + // succeeds, meaning there is no error for not having inference candidates. An + // inference error only occurs when there are *conflicting* candidates, i.e. + // candidates with no common supertype. + const defaultType = getDefaultFromTypeParameter(inference.typeParameter); + if (defaultType) { + // Instantiate the default type. Any forward reference to a type + // parameter should be instantiated to the empty object type. + inferredType = instantiateType(defaultType, mergeTypeMappers(createBackreferenceMapper(context, index), context.nonFixingMapper)); + } + } + } + else { + inferredType = getTypeFromInference(inference); + } + + inference.inferredType = inferredType || getDefaultTypeArgumentType(!!(context.flags & InferenceFlags.AnyDefault)); + + const constraint = getConstraintOfTypeParameter(inference.typeParameter); + if (constraint) { + const instantiatedConstraint = instantiateType(constraint, context.nonFixingMapper); + if (!inferredType || !context.compareTypes(inferredType, getTypeWithThisArgument(instantiatedConstraint, inferredType))) { + // If the fallback type satisfies the constraint, we pick it. Otherwise, we pick the constraint. + inference.inferredType = fallbackType && context.compareTypes(fallbackType, getTypeWithThisArgument(instantiatedConstraint, fallbackType)) ? fallbackType : instantiatedConstraint; + } + } + } + + return inference.inferredType; + } + + function getDefaultTypeArgumentType(isInJavaScriptFile: boolean): Type { + return isInJavaScriptFile ? anyType : unknownType; + } + + function getInferredTypes(context: InferenceContext): Type[] { + const result: Type[] = []; + for (let i = 0; i < context.inferences.length; i++) { + result.push(getInferredType(context, i)); + } + return result; + } + + // EXPRESSION TYPE CHECKING + + function getCannotFindNameDiagnosticForName(node: Identifier): DiagnosticMessage { + switch (node.escapedText) { + case "document": + case "console": + return Diagnostics.Cannot_find_name_0_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_include_dom; + case "$": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_jQuery_Try_npm_i_save_dev_types_Slashjquery_and_then_add_jquery_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_jQuery_Try_npm_i_save_dev_types_Slashjquery; + case "describe": + case "suite": + case "it": + case "test": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_a_test_runner_Try_npm_i_save_dev_types_Slashjest_or_npm_i_save_dev_types_Slashmocha_and_then_add_jest_or_mocha_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_a_test_runner_Try_npm_i_save_dev_types_Slashjest_or_npm_i_save_dev_types_Slashmocha; + case "process": + case "require": + case "Buffer": + case "module": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_node_Try_npm_i_save_dev_types_Slashnode_and_then_add_node_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_node_Try_npm_i_save_dev_types_Slashnode; + case "Bun": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_Bun_Try_npm_i_save_dev_types_Slashbun_and_then_add_bun_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_Bun_Try_npm_i_save_dev_types_Slashbun; + case "Map": + case "Set": + case "Promise": + case "Symbol": + case "WeakMap": + case "WeakSet": + case "Iterator": + case "AsyncIterator": + case "SharedArrayBuffer": + case "Atomics": + case "AsyncIterable": + case "AsyncIterableIterator": + case "AsyncGenerator": + case "AsyncGeneratorFunction": + case "BigInt": + case "Reflect": + case "BigInt64Array": + case "BigUint64Array": + return Diagnostics.Cannot_find_name_0_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_1_or_later; + case "await": + if (isCallExpression(node.parent)) { + return Diagnostics.Cannot_find_name_0_Did_you_mean_to_write_this_in_an_async_function; + } + // falls through + default: + if (node.parent.kind === SyntaxKind.ShorthandPropertyAssignment) { + return Diagnostics.No_value_exists_in_scope_for_the_shorthand_property_0_Either_declare_one_or_provide_an_initializer; + } + else { + return Diagnostics.Cannot_find_name_0; + } + } + } + + function getResolvedSymbol(node: Identifier): Symbol { + const links = getNodeLinks(node); + if (!links.resolvedSymbol) { + links.resolvedSymbol = !nodeIsMissing(node) && + resolveName( + node, + node, + SymbolFlags.Value | SymbolFlags.ExportValue, + getCannotFindNameDiagnosticForName(node), + !isWriteOnlyAccess(node), + /*excludeGlobals*/ false, + ) || unknownSymbol; + } + return links.resolvedSymbol; + } + + function isInAmbientOrTypeNode(node: Node): boolean { + return !!(node.flags & NodeFlags.Ambient || findAncestor(node, n => isInterfaceDeclaration(n) || isTypeAliasDeclaration(n) || isTypeLiteralNode(n))); + } + + // Return the flow cache key for a "dotted name" (i.e. a sequence of identifiers + // separated by dots). The key consists of the id of the symbol referenced by the + // leftmost identifier followed by zero or more property names separated by dots. + // The result is undefined if the reference isn't a dotted name. + function getFlowCacheKey(node: Node, declaredType: Type, initialType: Type, flowContainer: Node | undefined): string | undefined { + switch (node.kind) { + case SyntaxKind.Identifier: + if (!isThisInTypeQuery(node)) { + const symbol = getResolvedSymbol(node as Identifier); + return symbol !== unknownSymbol ? `${flowContainer ? getNodeId(flowContainer) : "-1"}|${getTypeId(declaredType)}|${getTypeId(initialType)}|${getSymbolId(symbol)}` : undefined; + } + // falls through + case SyntaxKind.ThisKeyword: + return `0|${flowContainer ? getNodeId(flowContainer) : "-1"}|${getTypeId(declaredType)}|${getTypeId(initialType)}`; + case SyntaxKind.NonNullExpression: + case SyntaxKind.ParenthesizedExpression: + return getFlowCacheKey((node as NonNullExpression | ParenthesizedExpression).expression, declaredType, initialType, flowContainer); + case SyntaxKind.QualifiedName: + const left = getFlowCacheKey((node as QualifiedName).left, declaredType, initialType, flowContainer); + return left && `${left}.${(node as QualifiedName).right.escapedText}`; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + const propName = getAccessedPropertyName(node as AccessExpression); + if (propName !== undefined) { + const key = getFlowCacheKey((node as AccessExpression).expression, declaredType, initialType, flowContainer); + return key && `${key}.${propName}`; + } + if (isElementAccessExpression(node) && isIdentifier(node.argumentExpression)) { + const symbol = getResolvedSymbol(node.argumentExpression); + if (isConstantVariable(symbol) || isParameterOrMutableLocalVariable(symbol) && !isSymbolAssigned(symbol)) { + const key = getFlowCacheKey((node as AccessExpression).expression, declaredType, initialType, flowContainer); + return key && `${key}.@${getSymbolId(symbol)}`; + } + } + break; + case SyntaxKind.ObjectBindingPattern: + case SyntaxKind.ArrayBindingPattern: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + // Handle pseudo-references originating in getNarrowedTypeOfSymbol. + return `${getNodeId(node)}#${getTypeId(declaredType)}`; + } + return undefined; + } + + function isMatchingReference(source: Node, target: Node): boolean { + switch (target.kind) { + case SyntaxKind.ParenthesizedExpression: + case SyntaxKind.NonNullExpression: + return isMatchingReference(source, (target as NonNullExpression | ParenthesizedExpression).expression); + case SyntaxKind.BinaryExpression: + return (isAssignmentExpression(target) && isMatchingReference(source, target.left)) || + (isBinaryExpression(target) && target.operatorToken.kind === SyntaxKind.CommaToken && isMatchingReference(source, target.right)); + } + switch (source.kind) { + case SyntaxKind.MetaProperty: + return target.kind === SyntaxKind.MetaProperty + && (source as MetaProperty).keywordToken === (target as MetaProperty).keywordToken + && (source as MetaProperty).name.escapedText === (target as MetaProperty).name.escapedText; + case SyntaxKind.Identifier: + case SyntaxKind.PrivateIdentifier: + return isThisInTypeQuery(source) ? + target.kind === SyntaxKind.ThisKeyword : + target.kind === SyntaxKind.Identifier && getResolvedSymbol(source as Identifier) === getResolvedSymbol(target as Identifier) || + (isVariableDeclaration(target) || isBindingElement(target)) && + getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(source as Identifier)) === getSymbolOfDeclaration(target); + case SyntaxKind.ThisKeyword: + return target.kind === SyntaxKind.ThisKeyword; + case SyntaxKind.SuperKeyword: + return target.kind === SyntaxKind.SuperKeyword; + case SyntaxKind.NonNullExpression: + case SyntaxKind.ParenthesizedExpression: + return isMatchingReference((source as NonNullExpression | ParenthesizedExpression).expression, target); + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + const sourcePropertyName = getAccessedPropertyName(source as AccessExpression); + if (sourcePropertyName !== undefined) { + const targetPropertyName = isAccessExpression(target) ? getAccessedPropertyName(target) : undefined; + if (targetPropertyName !== undefined) { + return targetPropertyName === sourcePropertyName && isMatchingReference((source as AccessExpression).expression, (target as AccessExpression).expression); + } + } + if (isElementAccessExpression(source) && isElementAccessExpression(target) && isIdentifier(source.argumentExpression) && isIdentifier(target.argumentExpression)) { + const symbol = getResolvedSymbol(source.argumentExpression); + if (symbol === getResolvedSymbol(target.argumentExpression) && (isConstantVariable(symbol) || isParameterOrMutableLocalVariable(symbol) && !isSymbolAssigned(symbol))) { + return isMatchingReference(source.expression, target.expression); + } + } + break; + case SyntaxKind.QualifiedName: + return isAccessExpression(target) && + (source as QualifiedName).right.escapedText === getAccessedPropertyName(target) && + isMatchingReference((source as QualifiedName).left, target.expression); + case SyntaxKind.BinaryExpression: + return (isBinaryExpression(source) && source.operatorToken.kind === SyntaxKind.CommaToken && isMatchingReference(source.right, target)); + } + return false; + } + + function getAccessedPropertyName(access: AccessExpression | BindingElement | ParameterDeclaration): __String | undefined { + if (isPropertyAccessExpression(access)) { + return access.name.escapedText; + } + if (isElementAccessExpression(access)) { + return tryGetElementAccessExpressionName(access); + } + if (isBindingElement(access)) { + const name = getDestructuringPropertyName(access); + return name ? escapeLeadingUnderscores(name) : undefined; + } + if (isParameter(access)) { + return ("" + access.parent.parameters.indexOf(access)) as __String; + } + return undefined; + } + + function tryGetNameFromType(type: Type) { + return type.flags & TypeFlags.UniqueESSymbol ? (type as UniqueESSymbolType).escapedName : + type.flags & TypeFlags.StringOrNumberLiteral ? escapeLeadingUnderscores("" + (type as StringLiteralType | NumberLiteralType).value) : undefined; + } + + function tryGetElementAccessExpressionName(node: ElementAccessExpression) { + return isStringOrNumericLiteralLike(node.argumentExpression) ? escapeLeadingUnderscores(node.argumentExpression.text) : + isEntityNameExpression(node.argumentExpression) ? tryGetNameFromEntityNameExpression(node.argumentExpression) : undefined; + } + + function tryGetNameFromEntityNameExpression(node: EntityNameOrEntityNameExpression) { + const symbol = resolveEntityName(node, SymbolFlags.Value, /*ignoreErrors*/ true); + if (!symbol || !(isConstantVariable(symbol) || (symbol.flags & SymbolFlags.EnumMember))) return undefined; + + const declaration = symbol.valueDeclaration; + if (declaration === undefined) return undefined; + + const type = tryGetTypeFromEffectiveTypeNode(declaration); + if (type) { + const name = tryGetNameFromType(type); + if (name !== undefined) { + return name; + } + } + if (hasOnlyExpressionInitializer(declaration) && isBlockScopedNameDeclaredBeforeUse(declaration, node)) { + const initializer = getEffectiveInitializer(declaration); + if (initializer) { + const initializerType = isBindingPattern(declaration.parent) ? getTypeForBindingElement(declaration as BindingElement) : getTypeOfExpression(initializer); + return initializerType && tryGetNameFromType(initializerType); + } + if (isEnumMember(declaration)) { + return getTextOfPropertyName(declaration.name); + } + } + return undefined; + } + + function containsMatchingReference(source: Node, target: Node) { + while (isAccessExpression(source)) { + source = source.expression; + if (isMatchingReference(source, target)) { + return true; + } + } + return false; + } + + function optionalChainContainsReference(source: Node, target: Node) { + while (isOptionalChain(source)) { + source = source.expression; + if (isMatchingReference(source, target)) { + return true; + } + } + return false; + } + + function isDiscriminantProperty(type: Type | undefined, name: __String) { + if (type && type.flags & TypeFlags.Union) { + const prop = getUnionOrIntersectionProperty(type as UnionType, name); + if (prop && getCheckFlags(prop) & CheckFlags.SyntheticProperty) { + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.SyntheticProperty + if ((prop as TransientSymbol).links.isDiscriminantProperty === undefined) { + (prop as TransientSymbol).links.isDiscriminantProperty = ((prop as TransientSymbol).links.checkFlags & CheckFlags.Discriminant) === CheckFlags.Discriminant && + !isGenericType(getTypeOfSymbol(prop)); + } + return !!(prop as TransientSymbol).links.isDiscriminantProperty; + } + } + return false; + } + + function findDiscriminantProperties(sourceProperties: Symbol[], target: Type): Symbol[] | undefined { + let result: Symbol[] | undefined; + for (const sourceProperty of sourceProperties) { + if (isDiscriminantProperty(target, sourceProperty.escapedName)) { + if (result) { + result.push(sourceProperty); + continue; + } + result = [sourceProperty]; + } + } + return result; + } + + // Given a set of constituent types and a property name, create and return a map keyed by the literal + // types of the property by that name in each constituent type. No map is returned if some key property + // has a non-literal type or if less than 10 or less than 50% of the constituents have a unique key. + // Entries with duplicate keys have unknownType as the value. + function mapTypesByKeyProperty(types: Type[], name: __String) { + const map = new Map(); + let count = 0; + for (const type of types) { + if (type.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive)) { + const discriminant = getTypeOfPropertyOfType(type, name); + if (discriminant) { + if (!isLiteralType(discriminant)) { + return undefined; + } + let duplicate = false; + forEachType(discriminant, t => { + const id = getTypeId(getRegularTypeOfLiteralType(t)); + const existing = map.get(id); + if (!existing) { + map.set(id, type); + } + else if (existing !== unknownType) { + map.set(id, unknownType); + duplicate = true; + } + }); + if (!duplicate) count++; + } + } + } + return count >= 10 && count * 2 >= types.length ? map : undefined; + } + + // Return the name of a discriminant property for which it was possible and feasible to construct a map of + // constituent types keyed by the literal types of the property by that name in each constituent type. + function getKeyPropertyName(unionType: UnionType): __String | undefined { + const types = unionType.types; + // We only construct maps for unions with many non-primitive constituents. + if ( + types.length < 10 || getObjectFlags(unionType) & ObjectFlags.PrimitiveUnion || + countWhere(types, t => !!(t.flags & (TypeFlags.Object | TypeFlags.InstantiableNonPrimitive))) < 10 + ) { + return undefined; + } + if (unionType.keyPropertyName === undefined) { + // The candidate key property name is the name of the first property with a unit type in one of the + // constituent types. + const keyPropertyName = forEach(types, t => + t.flags & (TypeFlags.Object | TypeFlags.InstantiableNonPrimitive) ? + forEach(getPropertiesOfType(t), p => isUnitType(getTypeOfSymbol(p)) ? p.escapedName : undefined) : + undefined); + const mapByKeyProperty = keyPropertyName && mapTypesByKeyProperty(types, keyPropertyName); + unionType.keyPropertyName = mapByKeyProperty ? keyPropertyName : "" as __String; + unionType.constituentMap = mapByKeyProperty; + } + return (unionType.keyPropertyName as string).length ? unionType.keyPropertyName : undefined; + } + + // Given a union type for which getKeyPropertyName returned a non-undefined result, return the constituent + // that corresponds to the given key type for that property name. + function getConstituentTypeForKeyType(unionType: UnionType, keyType: Type) { + const result = unionType.constituentMap?.get(getTypeId(getRegularTypeOfLiteralType(keyType))); + return result !== unknownType ? result : undefined; + } + + function getMatchingUnionConstituentForType(unionType: UnionType, type: Type) { + const keyPropertyName = getKeyPropertyName(unionType); + const propType = keyPropertyName && getTypeOfPropertyOfType(type, keyPropertyName); + return propType && getConstituentTypeForKeyType(unionType, propType); + } + + function getMatchingUnionConstituentForObjectLiteral(unionType: UnionType, node: ObjectLiteralExpression) { + const keyPropertyName = getKeyPropertyName(unionType); + const propNode = keyPropertyName && find(node.properties, p => + p.symbol && p.kind === SyntaxKind.PropertyAssignment && + p.symbol.escapedName === keyPropertyName && isPossiblyDiscriminantValue(p.initializer)); + const propType = propNode && getContextFreeTypeOfExpression((propNode as PropertyAssignment).initializer); + return propType && getConstituentTypeForKeyType(unionType, propType); + } + + function isOrContainsMatchingReference(source: Node, target: Node) { + return isMatchingReference(source, target) || containsMatchingReference(source, target); + } + + function hasMatchingArgument(expression: CallExpression | NewExpression, reference: Node) { + if (expression.arguments) { + for (const argument of expression.arguments) { + if (isOrContainsMatchingReference(reference, argument) || optionalChainContainsReference(argument, reference)) { + return true; + } + } + } + if ( + expression.expression.kind === SyntaxKind.PropertyAccessExpression && + isOrContainsMatchingReference(reference, (expression.expression as PropertyAccessExpression).expression) + ) { + return true; + } + return false; + } + + function getFlowNodeId(flow: FlowNode): number { + if (flow.id <= 0) { + flow.id = nextFlowId; + nextFlowId++; + } + return flow.id; + } + + function typeMaybeAssignableTo(source: Type, target: Type) { + if (!(source.flags & TypeFlags.Union)) { + return isTypeAssignableTo(source, target); + } + for (const t of (source as UnionType).types) { + if (isTypeAssignableTo(t, target)) { + return true; + } + } + return false; + } + + // Remove those constituent types of declaredType to which no constituent type of assignedType is assignable. + // For example, when a variable of type number | string | boolean is assigned a value of type number | boolean, + // we remove type string. + function getAssignmentReducedType(declaredType: UnionType, assignedType: Type) { + if (declaredType === assignedType) { + return declaredType; + } + if (assignedType.flags & TypeFlags.Never) { + return assignedType; + } + const key = `A${getTypeId(declaredType)},${getTypeId(assignedType)}`; + return getCachedType(key) ?? setCachedType(key, getAssignmentReducedTypeWorker(declaredType, assignedType)); + } + + function getAssignmentReducedTypeWorker(declaredType: UnionType, assignedType: Type) { + const filteredType = filterType(declaredType, t => typeMaybeAssignableTo(assignedType, t)); + // Ensure that we narrow to fresh types if the assignment is a fresh boolean literal type. + const reducedType = assignedType.flags & TypeFlags.BooleanLiteral && isFreshLiteralType(assignedType) ? mapType(filteredType, getFreshTypeOfLiteralType) : filteredType; + // Our crude heuristic produces an invalid result in some cases: see GH#26130. + // For now, when that happens, we give up and don't narrow at all. (This also + // means we'll never narrow for erroneous assignments where the assigned type + // is not assignable to the declared type.) + return isTypeAssignableTo(assignedType, reducedType) ? reducedType : declaredType; + } + + function isFunctionObjectType(type: ObjectType): boolean { + // We do a quick check for a "bind" property before performing the more expensive subtype + // check. This gives us a quicker out in the common case where an object type is not a function. + const resolved = resolveStructuredTypeMembers(type); + return !!(resolved.callSignatures.length || resolved.constructSignatures.length || + resolved.members.get("bind" as __String) && isTypeSubtypeOf(type, globalFunctionType)); + } + + function getTypeFacts(type: Type, mask: TypeFacts): TypeFacts { + return getTypeFactsWorker(type, mask) & mask; + } + + function hasTypeFacts(type: Type, mask: TypeFacts): boolean { + return getTypeFacts(type, mask) !== 0; + } + + function getTypeFactsWorker(type: Type, callerOnlyNeeds: TypeFacts): TypeFacts { + if (type.flags & (TypeFlags.Intersection | TypeFlags.Instantiable)) { + type = getBaseConstraintOfType(type) || unknownType; + } + const flags = type.flags; + if (flags & (TypeFlags.String | TypeFlags.StringMapping)) { + return strictNullChecks ? TypeFacts.StringStrictFacts : TypeFacts.StringFacts; + } + if (flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral)) { + const isEmpty = flags & TypeFlags.StringLiteral && (type as StringLiteralType).value === ""; + return strictNullChecks ? + isEmpty ? TypeFacts.EmptyStringStrictFacts : TypeFacts.NonEmptyStringStrictFacts : + isEmpty ? TypeFacts.EmptyStringFacts : TypeFacts.NonEmptyStringFacts; + } + if (flags & (TypeFlags.Number | TypeFlags.Enum)) { + return strictNullChecks ? TypeFacts.NumberStrictFacts : TypeFacts.NumberFacts; + } + if (flags & TypeFlags.NumberLiteral) { + const isZero = (type as NumberLiteralType).value === 0; + return strictNullChecks ? + isZero ? TypeFacts.ZeroNumberStrictFacts : TypeFacts.NonZeroNumberStrictFacts : + isZero ? TypeFacts.ZeroNumberFacts : TypeFacts.NonZeroNumberFacts; + } + if (flags & TypeFlags.BigInt) { + return strictNullChecks ? TypeFacts.BigIntStrictFacts : TypeFacts.BigIntFacts; + } + if (flags & TypeFlags.BigIntLiteral) { + const isZero = isZeroBigInt(type as BigIntLiteralType); + return strictNullChecks ? + isZero ? TypeFacts.ZeroBigIntStrictFacts : TypeFacts.NonZeroBigIntStrictFacts : + isZero ? TypeFacts.ZeroBigIntFacts : TypeFacts.NonZeroBigIntFacts; + } + if (flags & TypeFlags.Boolean) { + return strictNullChecks ? TypeFacts.BooleanStrictFacts : TypeFacts.BooleanFacts; + } + if (flags & TypeFlags.BooleanLike) { + return strictNullChecks ? + (type === falseType || type === regularFalseType) ? TypeFacts.FalseStrictFacts : TypeFacts.TrueStrictFacts : + (type === falseType || type === regularFalseType) ? TypeFacts.FalseFacts : TypeFacts.TrueFacts; + } + if (flags & TypeFlags.Object) { + const possibleFacts = strictNullChecks + ? TypeFacts.EmptyObjectStrictFacts | TypeFacts.FunctionStrictFacts | TypeFacts.ObjectStrictFacts + : TypeFacts.EmptyObjectFacts | TypeFacts.FunctionFacts | TypeFacts.ObjectFacts; + + if ((callerOnlyNeeds & possibleFacts) === 0) { + // If the caller doesn't care about any of the facts that we could possibly produce, + // return zero so we can skip resolving members. + return 0; + } + + return getObjectFlags(type) & ObjectFlags.Anonymous && isEmptyObjectType(type as ObjectType) ? + strictNullChecks ? TypeFacts.EmptyObjectStrictFacts : TypeFacts.EmptyObjectFacts : + isFunctionObjectType(type as ObjectType) ? + strictNullChecks ? TypeFacts.FunctionStrictFacts : TypeFacts.FunctionFacts : + strictNullChecks ? TypeFacts.ObjectStrictFacts : TypeFacts.ObjectFacts; + } + if (flags & TypeFlags.Void) { + return TypeFacts.VoidFacts; + } + if (flags & TypeFlags.Undefined) { + return TypeFacts.UndefinedFacts; + } + if (flags & TypeFlags.Null) { + return TypeFacts.NullFacts; + } + if (flags & TypeFlags.ESSymbolLike) { + return strictNullChecks ? TypeFacts.SymbolStrictFacts : TypeFacts.SymbolFacts; + } + if (flags & TypeFlags.NonPrimitive) { + return strictNullChecks ? TypeFacts.ObjectStrictFacts : TypeFacts.ObjectFacts; + } + if (flags & TypeFlags.Never) { + return TypeFacts.None; + } + if (flags & TypeFlags.Union) { + return reduceLeft((type as UnionType).types, (facts, t) => facts | getTypeFactsWorker(t, callerOnlyNeeds), TypeFacts.None); + } + if (flags & TypeFlags.Intersection) { + return getIntersectionTypeFacts(type as IntersectionType, callerOnlyNeeds); + } + return TypeFacts.UnknownFacts; + } + + function getIntersectionTypeFacts(type: IntersectionType, callerOnlyNeeds: TypeFacts): TypeFacts { + // When an intersection contains a primitive type we ignore object type constituents as they are + // presumably type tags. For example, in string & { __kind__: "name" } we ignore the object type. + const ignoreObjects = maybeTypeOfKind(type, TypeFlags.Primitive); + // When computing the type facts of an intersection type, certain type facts are computed as `and` + // and others are computed as `or`. + let oredFacts = TypeFacts.None; + let andedFacts = TypeFacts.All; + for (const t of type.types) { + if (!(ignoreObjects && t.flags & TypeFlags.Object)) { + const f = getTypeFactsWorker(t, callerOnlyNeeds); + oredFacts |= f; + andedFacts &= f; + } + } + return oredFacts & TypeFacts.OrFactsMask | andedFacts & TypeFacts.AndFactsMask; + } + + function getTypeWithFacts(type: Type, include: TypeFacts) { + return filterType(type, t => hasTypeFacts(t, include)); + } + + // This function is similar to getTypeWithFacts, except that in strictNullChecks mode it replaces type + // unknown with the union {} | null | undefined (and reduces that accordingly), and it intersects remaining + // instantiable types with {}, {} | null, or {} | undefined in order to remove null and/or undefined. + function getAdjustedTypeWithFacts(type: Type, facts: TypeFacts) { + const reduced = recombineUnknownType(getTypeWithFacts(strictNullChecks && type.flags & TypeFlags.Unknown ? unknownUnionType : type, facts)); + if (strictNullChecks) { + switch (facts) { + case TypeFacts.NEUndefined: + return removeNullableByIntersection(reduced, TypeFacts.EQUndefined, TypeFacts.EQNull, TypeFacts.IsNull, nullType); + case TypeFacts.NENull: + return removeNullableByIntersection(reduced, TypeFacts.EQNull, TypeFacts.EQUndefined, TypeFacts.IsUndefined, undefinedType); + case TypeFacts.NEUndefinedOrNull: + case TypeFacts.Truthy: + return mapType(reduced, t => hasTypeFacts(t, TypeFacts.EQUndefinedOrNull) ? getGlobalNonNullableTypeInstantiation(t) : t); + } + } + return reduced; + } + + function removeNullableByIntersection(type: Type, targetFacts: TypeFacts, otherFacts: TypeFacts, otherIncludesFacts: TypeFacts, otherType: Type) { + const facts = getTypeFacts(type, TypeFacts.EQUndefined | TypeFacts.EQNull | TypeFacts.IsUndefined | TypeFacts.IsNull); + // Simply return the type if it never compares equal to the target nullable. + if (!(facts & targetFacts)) { + return type; + } + // By default we intersect with a union of {} and the opposite nullable. + const emptyAndOtherUnion = getUnionType([emptyObjectType, otherType]); + // For each constituent type that can compare equal to the target nullable, intersect with the above union + // if the type doesn't already include the opppsite nullable and the constituent can compare equal to the + // opposite nullable; otherwise, just intersect with {}. + return mapType(type, t => hasTypeFacts(t, targetFacts) ? getIntersectionType([t, !(facts & otherIncludesFacts) && hasTypeFacts(t, otherFacts) ? emptyAndOtherUnion : emptyObjectType]) : t); + } + + function recombineUnknownType(type: Type) { + return type === unknownUnionType ? unknownType : type; + } + + function getTypeWithDefault(type: Type, defaultExpression: Expression) { + return defaultExpression ? + getUnionType([getNonUndefinedType(type), getTypeOfExpression(defaultExpression)]) : + type; + } + + function getTypeOfDestructuredProperty(type: Type, name: PropertyName) { + const nameType = getLiteralTypeFromPropertyName(name); + if (!isTypeUsableAsPropertyName(nameType)) return errorType; + const text = getPropertyNameFromType(nameType); + return getTypeOfPropertyOfType(type, text) || includeUndefinedInIndexSignature(getApplicableIndexInfoForName(type, text)?.type) || errorType; + } + + function getTypeOfDestructuredArrayElement(type: Type, index: number) { + return everyType(type, isTupleLikeType) && getTupleElementType(type, index) || + includeUndefinedInIndexSignature(checkIteratedTypeOrElementType(IterationUse.Destructuring, type, undefinedType, /*errorNode*/ undefined)) || + errorType; + } + + function includeUndefinedInIndexSignature(type: Type | undefined): Type | undefined { + if (!type) return type; + return compilerOptions.noUncheckedIndexedAccess ? + getUnionType([type, missingType]) : + type; + } + + function getTypeOfDestructuredSpreadExpression(type: Type) { + return createArrayType(checkIteratedTypeOrElementType(IterationUse.Destructuring, type, undefinedType, /*errorNode*/ undefined) || errorType); + } + + function getAssignedTypeOfBinaryExpression(node: BinaryExpression): Type { + const isDestructuringDefaultAssignment = node.parent.kind === SyntaxKind.ArrayLiteralExpression && isDestructuringAssignmentTarget(node.parent) || + node.parent.kind === SyntaxKind.PropertyAssignment && isDestructuringAssignmentTarget(node.parent.parent); + return isDestructuringDefaultAssignment ? + getTypeWithDefault(getAssignedType(node), node.right) : + getTypeOfExpression(node.right); + } + + function isDestructuringAssignmentTarget(parent: Node) { + return parent.parent.kind === SyntaxKind.BinaryExpression && (parent.parent as BinaryExpression).left === parent || + parent.parent.kind === SyntaxKind.ForOfStatement && (parent.parent as ForOfStatement).initializer === parent; + } + + function getAssignedTypeOfArrayLiteralElement(node: ArrayLiteralExpression, element: Expression): Type { + return getTypeOfDestructuredArrayElement(getAssignedType(node), node.elements.indexOf(element)); + } + + function getAssignedTypeOfSpreadExpression(node: SpreadElement): Type { + return getTypeOfDestructuredSpreadExpression(getAssignedType(node.parent as ArrayLiteralExpression)); + } + + function getAssignedTypeOfPropertyAssignment(node: PropertyAssignment | ShorthandPropertyAssignment): Type { + return getTypeOfDestructuredProperty(getAssignedType(node.parent), node.name); + } + + function getAssignedTypeOfShorthandPropertyAssignment(node: ShorthandPropertyAssignment): Type { + return getTypeWithDefault(getAssignedTypeOfPropertyAssignment(node), node.objectAssignmentInitializer!); + } + + function getAssignedType(node: Expression): Type { + const { parent } = node; + switch (parent.kind) { + case SyntaxKind.ForInStatement: + return stringType; + case SyntaxKind.ForOfStatement: + return checkRightHandSideOfForOf(parent as ForOfStatement) || errorType; + case SyntaxKind.BinaryExpression: + return getAssignedTypeOfBinaryExpression(parent as BinaryExpression); + case SyntaxKind.DeleteExpression: + return undefinedType; + case SyntaxKind.ArrayLiteralExpression: + return getAssignedTypeOfArrayLiteralElement(parent as ArrayLiteralExpression, node); + case SyntaxKind.SpreadElement: + return getAssignedTypeOfSpreadExpression(parent as SpreadElement); + case SyntaxKind.PropertyAssignment: + return getAssignedTypeOfPropertyAssignment(parent as PropertyAssignment); + case SyntaxKind.ShorthandPropertyAssignment: + return getAssignedTypeOfShorthandPropertyAssignment(parent as ShorthandPropertyAssignment); + } + return errorType; + } + + function getInitialTypeOfBindingElement(node: BindingElement): Type { + const pattern = node.parent; + const parentType = getInitialType(pattern.parent as VariableDeclaration | BindingElement); + const type = pattern.kind === SyntaxKind.ObjectBindingPattern ? + getTypeOfDestructuredProperty(parentType, node.propertyName || node.name as Identifier) : + !node.dotDotDotToken ? + getTypeOfDestructuredArrayElement(parentType, pattern.elements.indexOf(node)) : + getTypeOfDestructuredSpreadExpression(parentType); + return getTypeWithDefault(type, node.initializer!); + } + + function getTypeOfInitializer(node: Expression) { + // Return the cached type if one is available. If the type of the variable was inferred + // from its initializer, we'll already have cached the type. Otherwise we compute it now + // without caching such that transient types are reflected. + const links = getNodeLinks(node); + return links.resolvedType || getTypeOfExpression(node); + } + + function getInitialTypeOfVariableDeclaration(node: VariableDeclaration) { + if (node.initializer) { + return getTypeOfInitializer(node.initializer); + } + if (node.parent.parent.kind === SyntaxKind.ForInStatement) { + return stringType; + } + if (node.parent.parent.kind === SyntaxKind.ForOfStatement) { + return checkRightHandSideOfForOf(node.parent.parent) || errorType; + } + return errorType; + } + + function getInitialType(node: VariableDeclaration | BindingElement) { + return node.kind === SyntaxKind.VariableDeclaration ? + getInitialTypeOfVariableDeclaration(node) : + getInitialTypeOfBindingElement(node); + } + + function isEmptyArrayAssignment(node: VariableDeclaration | BindingElement | Expression) { + return node.kind === SyntaxKind.VariableDeclaration && (node as VariableDeclaration).initializer && + isEmptyArrayLiteral((node as VariableDeclaration).initializer!) || + node.kind !== SyntaxKind.BindingElement && node.parent.kind === SyntaxKind.BinaryExpression && + isEmptyArrayLiteral((node.parent as BinaryExpression).right); + } + + function getReferenceCandidate(node: Expression): Expression { + switch (node.kind) { + case SyntaxKind.ParenthesizedExpression: + return getReferenceCandidate((node as ParenthesizedExpression).expression); + case SyntaxKind.BinaryExpression: + switch ((node as BinaryExpression).operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.BarBarEqualsToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: + case SyntaxKind.QuestionQuestionEqualsToken: + return getReferenceCandidate((node as BinaryExpression).left); + case SyntaxKind.CommaToken: + return getReferenceCandidate((node as BinaryExpression).right); + } + } + return node; + } + + function getReferenceRoot(node: Node): Node { + const { parent } = node; + return parent.kind === SyntaxKind.ParenthesizedExpression || + parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken && (parent as BinaryExpression).left === node || + parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.CommaToken && (parent as BinaryExpression).right === node ? + getReferenceRoot(parent) : node; + } + + function getTypeOfSwitchClause(clause: CaseClause | DefaultClause) { + if (clause.kind === SyntaxKind.CaseClause) { + return getRegularTypeOfLiteralType(getTypeOfExpression(clause.expression)); + } + return neverType; + } + + function getSwitchClauseTypes(switchStatement: SwitchStatement): Type[] { + const links = getNodeLinks(switchStatement); + if (!links.switchTypes) { + links.switchTypes = []; + for (const clause of switchStatement.caseBlock.clauses) { + links.switchTypes.push(getTypeOfSwitchClause(clause)); + } + } + return links.switchTypes; + } + + // Get the type names from all cases in a switch on `typeof`. The default clause and/or duplicate type names are + // represented as undefined. Return undefined if one or more case clause expressions are not string literals. + function getSwitchClauseTypeOfWitnesses(switchStatement: SwitchStatement): (string | undefined)[] | undefined { + if (some(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.CaseClause && !isStringLiteralLike(clause.expression))) { + return undefined; + } + const witnesses: (string | undefined)[] = []; + for (const clause of switchStatement.caseBlock.clauses) { + const text = clause.kind === SyntaxKind.CaseClause ? (clause.expression as StringLiteralLike).text : undefined; + witnesses.push(text && !contains(witnesses, text) ? text : undefined); + } + return witnesses; + } + + function eachTypeContainedIn(source: Type, types: Type[]) { + return source.flags & TypeFlags.Union ? !forEach((source as UnionType).types, t => !contains(types, t)) : contains(types, source); + } + + function isTypeSubsetOf(source: Type, target: Type) { + return !!(source === target || source.flags & TypeFlags.Never || target.flags & TypeFlags.Union && isTypeSubsetOfUnion(source, target as UnionType)); + } + + function isTypeSubsetOfUnion(source: Type, target: UnionType) { + if (source.flags & TypeFlags.Union) { + for (const t of (source as UnionType).types) { + if (!containsType(target.types, t)) { + return false; + } + } + return true; + } + if (source.flags & TypeFlags.EnumLike && getBaseTypeOfEnumLikeType(source as LiteralType) === target) { + return true; + } + return containsType(target.types, source); + } + + function forEachType(type: Type, f: (t: Type) => T | undefined): T | undefined { + return type.flags & TypeFlags.Union ? forEach((type as UnionType).types, f) : f(type); + } + + function someType(type: Type, f: (t: Type) => boolean): boolean { + return type.flags & TypeFlags.Union ? some((type as UnionType).types, f) : f(type); + } + + function everyType(type: Type, f: (t: Type) => boolean): boolean { + return type.flags & TypeFlags.Union ? every((type as UnionType).types, f) : f(type); + } + + function everyContainedType(type: Type, f: (t: Type) => boolean): boolean { + return type.flags & TypeFlags.UnionOrIntersection ? every((type as UnionOrIntersectionType).types, f) : f(type); + } + + function filterType(type: Type, f: (t: Type) => boolean): Type { + if (type.flags & TypeFlags.Union) { + const types = (type as UnionType).types; + const filtered = filter(types, f); + if (filtered === types) { + return type; + } + const origin = (type as UnionType).origin; + let newOrigin: Type | undefined; + if (origin && origin.flags & TypeFlags.Union) { + // If the origin type is a (denormalized) union type, filter its non-union constituents. If that ends + // up removing a smaller number of types than in the normalized constituent set (meaning some of the + // filtered types are within nested unions in the origin), then we can't construct a new origin type. + // Otherwise, if we have exactly one type left in the origin set, return that as the filtered type. + // Otherwise, construct a new filtered origin type. + const originTypes = (origin as UnionType).types; + const originFiltered = filter(originTypes, t => !!(t.flags & TypeFlags.Union) || f(t)); + if (originTypes.length - originFiltered.length === types.length - filtered.length) { + if (originFiltered.length === 1) { + return originFiltered[0]; + } + newOrigin = createOriginUnionOrIntersectionType(TypeFlags.Union, originFiltered); + } + } + // filtering could remove intersections so `ContainsIntersections` might be forwarded "incorrectly" + // it is purely an optimization hint so there is no harm in accidentally forwarding it + return getUnionTypeFromSortedList(filtered, (type as UnionType).objectFlags & (ObjectFlags.PrimitiveUnion | ObjectFlags.ContainsIntersections), /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined, newOrigin); + } + return type.flags & TypeFlags.Never || f(type) ? type : neverType; + } + + function removeType(type: Type, targetType: Type) { + return filterType(type, t => t !== targetType); + } + + function countTypes(type: Type) { + return type.flags & TypeFlags.Union ? (type as UnionType).types.length : 1; + } + + // Apply a mapping function to a type and return the resulting type. If the source type + // is a union type, the mapping function is applied to each constituent type and a union + // of the resulting types is returned. + function mapType(type: Type, mapper: (t: Type) => Type, noReductions?: boolean): Type; + function mapType(type: Type, mapper: (t: Type) => Type | undefined, noReductions?: boolean): Type | undefined; + function mapType(type: Type, mapper: (t: Type) => Type | undefined, noReductions?: boolean): Type | undefined { + if (type.flags & TypeFlags.Never) { + return type; + } + if (!(type.flags & TypeFlags.Union)) { + return mapper(type); + } + const origin = (type as UnionType).origin; + const types = origin && origin.flags & TypeFlags.Union ? (origin as UnionType).types : (type as UnionType).types; + let mappedTypes: Type[] | undefined; + let changed = false; + for (const t of types) { + const mapped = t.flags & TypeFlags.Union ? mapType(t, mapper, noReductions) : mapper(t); + changed ||= t !== mapped; + if (mapped) { + if (!mappedTypes) { + mappedTypes = [mapped]; + } + else { + mappedTypes.push(mapped); + } + } + } + return changed ? mappedTypes && getUnionType(mappedTypes, noReductions ? UnionReduction.None : UnionReduction.Literal) : type; + } + + function mapTypeWithAlias(type: Type, mapper: (t: Type) => Type, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { + return type.flags & TypeFlags.Union && aliasSymbol ? + getUnionType(map((type as UnionType).types, mapper), UnionReduction.Literal, aliasSymbol, aliasTypeArguments) : + mapType(type, mapper); + } + + function extractTypesOfKind(type: Type, kind: TypeFlags) { + return filterType(type, t => (t.flags & kind) !== 0); + } + + // Return a new type in which occurrences of the string, number and bigint primitives and placeholder template + // literal types in typeWithPrimitives have been replaced with occurrences of compatible and more specific types + // from typeWithLiterals. This is essentially a limited form of intersection between the two types. We avoid a + // true intersection because it is more costly and, when applied to union types, generates a large number of + // types we don't actually care about. + function replacePrimitivesWithLiterals(typeWithPrimitives: Type, typeWithLiterals: Type) { + if ( + maybeTypeOfKind(typeWithPrimitives, TypeFlags.String | TypeFlags.TemplateLiteral | TypeFlags.Number | TypeFlags.BigInt) && + maybeTypeOfKind(typeWithLiterals, TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping | TypeFlags.NumberLiteral | TypeFlags.BigIntLiteral) + ) { + return mapType(typeWithPrimitives, t => + t.flags & TypeFlags.String ? extractTypesOfKind(typeWithLiterals, TypeFlags.String | TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) : + isPatternLiteralType(t) && !maybeTypeOfKind(typeWithLiterals, TypeFlags.String | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? extractTypesOfKind(typeWithLiterals, TypeFlags.StringLiteral) : + t.flags & TypeFlags.Number ? extractTypesOfKind(typeWithLiterals, TypeFlags.Number | TypeFlags.NumberLiteral) : + t.flags & TypeFlags.BigInt ? extractTypesOfKind(typeWithLiterals, TypeFlags.BigInt | TypeFlags.BigIntLiteral) : t); + } + return typeWithPrimitives; + } + + function isIncomplete(flowType: FlowType) { + return flowType.flags === 0; + } + + function getTypeFromFlowType(flowType: FlowType) { + return flowType.flags === 0 ? flowType.type : flowType as Type; + } + + function createFlowType(type: Type, incomplete: boolean): FlowType { + return incomplete ? { flags: 0, type: type.flags & TypeFlags.Never ? silentNeverType : type } : type; + } + + // An evolving array type tracks the element types that have so far been seen in an + // 'x.push(value)' or 'x[n] = value' operation along the control flow graph. Evolving + // array types are ultimately converted into manifest array types (using getFinalArrayType) + // and never escape the getFlowTypeOfReference function. + function createEvolvingArrayType(elementType: Type): EvolvingArrayType { + const result = createObjectType(ObjectFlags.EvolvingArray) as EvolvingArrayType; + result.elementType = elementType; + return result; + } + + function getEvolvingArrayType(elementType: Type): EvolvingArrayType { + return evolvingArrayTypes[elementType.id] || (evolvingArrayTypes[elementType.id] = createEvolvingArrayType(elementType)); + } + + // When adding evolving array element types we do not perform subtype reduction. Instead, + // we defer subtype reduction until the evolving array type is finalized into a manifest + // array type. + function addEvolvingArrayElementType(evolvingArrayType: EvolvingArrayType, node: Expression): EvolvingArrayType { + const elementType = getRegularTypeOfObjectLiteral(getBaseTypeOfLiteralType(getContextFreeTypeOfExpression(node))); + return isTypeSubsetOf(elementType, evolvingArrayType.elementType) ? evolvingArrayType : getEvolvingArrayType(getUnionType([evolvingArrayType.elementType, elementType])); + } + + function createFinalArrayType(elementType: Type) { + return elementType.flags & TypeFlags.Never ? + autoArrayType : + createArrayType( + elementType.flags & TypeFlags.Union ? + getUnionType((elementType as UnionType).types, UnionReduction.Subtype) : + elementType, + ); + } + + // We perform subtype reduction upon obtaining the final array type from an evolving array type. + function getFinalArrayType(evolvingArrayType: EvolvingArrayType): Type { + return evolvingArrayType.finalArrayType || (evolvingArrayType.finalArrayType = createFinalArrayType(evolvingArrayType.elementType)); + } + + function finalizeEvolvingArrayType(type: Type): Type { + return getObjectFlags(type) & ObjectFlags.EvolvingArray ? getFinalArrayType(type as EvolvingArrayType) : type; + } + + function getElementTypeOfEvolvingArrayType(type: Type) { + return getObjectFlags(type) & ObjectFlags.EvolvingArray ? (type as EvolvingArrayType).elementType : neverType; + } + + function isEvolvingArrayTypeList(types: Type[]) { + let hasEvolvingArrayType = false; + for (const t of types) { + if (!(t.flags & TypeFlags.Never)) { + if (!(getObjectFlags(t) & ObjectFlags.EvolvingArray)) { + return false; + } + hasEvolvingArrayType = true; + } + } + return hasEvolvingArrayType; + } + + // Return true if the given node is 'x' in an 'x.length', x.push(value)', 'x.unshift(value)' or + // 'x[n] = value' operation, where 'n' is an expression of type any, undefined, or a number-like type. + function isEvolvingArrayOperationTarget(node: Node) { + const root = getReferenceRoot(node); + const parent = root.parent; + const isLengthPushOrUnshift = isPropertyAccessExpression(parent) && ( + parent.name.escapedText === "length" || + parent.parent.kind === SyntaxKind.CallExpression + && isIdentifier(parent.name) + && isPushOrUnshiftIdentifier(parent.name) + ); + const isElementAssignment = parent.kind === SyntaxKind.ElementAccessExpression && + (parent as ElementAccessExpression).expression === root && + parent.parent.kind === SyntaxKind.BinaryExpression && + (parent.parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken && + (parent.parent as BinaryExpression).left === parent && + !isAssignmentTarget(parent.parent) && + isTypeAssignableToKind(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression), TypeFlags.NumberLike); + return isLengthPushOrUnshift || isElementAssignment; + } + + function isDeclarationWithExplicitTypeAnnotation(node: Declaration) { + return (isVariableDeclaration(node) || isPropertyDeclaration(node) || isPropertySignature(node) || isParameter(node)) && + !!(getEffectiveTypeAnnotationNode(node) || + isInJSFile(node) && hasInitializer(node) && node.initializer && isFunctionExpressionOrArrowFunction(node.initializer) && getEffectiveReturnTypeNode(node.initializer)); + } + + function getExplicitTypeOfSymbol(symbol: Symbol, diagnostic?: Diagnostic) { + symbol = resolveSymbol(symbol); + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.ValueModule)) { + return getTypeOfSymbol(symbol); + } + if (symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property)) { + if (getCheckFlags(symbol) & CheckFlags.Mapped) { + const origin = (symbol as MappedSymbol).links.syntheticOrigin; + if (origin && getExplicitTypeOfSymbol(origin)) { + return getTypeOfSymbol(symbol); + } + } + const declaration = symbol.valueDeclaration; + if (declaration) { + if (isDeclarationWithExplicitTypeAnnotation(declaration)) { + return getTypeOfSymbol(symbol); + } + if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForOfStatement) { + const statement = declaration.parent.parent; + const expressionType = getTypeOfDottedName(statement.expression, /*diagnostic*/ undefined); + if (expressionType) { + const use = statement.awaitModifier ? IterationUse.ForAwaitOf : IterationUse.ForOf; + return checkIteratedTypeOrElementType(use, expressionType, undefinedType, /*errorNode*/ undefined); + } + } + if (diagnostic) { + addRelatedInfo(diagnostic, createDiagnosticForNode(declaration, Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol))); + } + } + } + } + + // We require the dotted function name in an assertion expression to be comprised of identifiers + // that reference function, method, class or value module symbols; or variable, property or + // parameter symbols with declarations that have explicit type annotations. Such references are + // resolvable with no possibility of triggering circularities in control flow analysis. + function getTypeOfDottedName(node: Expression, diagnostic: Diagnostic | undefined): Type | undefined { + if (!(node.flags & NodeFlags.InWithStatement)) { + switch (node.kind) { + case SyntaxKind.Identifier: + const symbol = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(node as Identifier)); + return getExplicitTypeOfSymbol(symbol, diagnostic); + case SyntaxKind.ThisKeyword: + return getExplicitThisType(node); + case SyntaxKind.SuperKeyword: + return checkSuperExpression(node); + case SyntaxKind.PropertyAccessExpression: { + const type = getTypeOfDottedName((node as PropertyAccessExpression).expression, diagnostic); + if (type) { + const name = (node as PropertyAccessExpression).name; + let prop: Symbol | undefined; + if (isPrivateIdentifier(name)) { + if (!type.symbol) { + return undefined; + } + prop = getPropertyOfType(type, getSymbolNameForPrivateIdentifier(type.symbol, name.escapedText)); + } + else { + prop = getPropertyOfType(type, name.escapedText); + } + return prop && getExplicitTypeOfSymbol(prop, diagnostic); + } + return undefined; + } + case SyntaxKind.ParenthesizedExpression: + return getTypeOfDottedName((node as ParenthesizedExpression).expression, diagnostic); + } + } + } + + function getEffectsSignature(node: CallExpression | InstanceofExpression) { + const links = getNodeLinks(node); + let signature = links.effectsSignature; + if (signature === undefined) { + // A call expression parented by an expression statement is a potential assertion. Other call + // expressions are potential type predicate function calls. In order to avoid triggering + // circularities in control flow analysis, we use getTypeOfDottedName when resolving the call + // target expression of an assertion. + let funcType: Type | undefined; + if (isBinaryExpression(node)) { + const rightType = checkNonNullExpression(node.right); + funcType = getSymbolHasInstanceMethodOfObjectType(rightType); + } + else if (node.parent.kind === SyntaxKind.ExpressionStatement) { + funcType = getTypeOfDottedName(node.expression, /*diagnostic*/ undefined); + } + else if (node.expression.kind !== SyntaxKind.SuperKeyword) { + if (isOptionalChain(node)) { + funcType = checkNonNullType( + getOptionalExpressionType(checkExpression(node.expression), node.expression), + node.expression, + ); + } + else { + funcType = checkNonNullExpression(node.expression); + } + } + const signatures = getSignaturesOfType(funcType && getApparentType(funcType) || unknownType, SignatureKind.Call); + const candidate = signatures.length === 1 && !signatures[0].typeParameters ? signatures[0] : + some(signatures, hasTypePredicateOrNeverReturnType) ? getResolvedSignature(node) : + undefined; + signature = links.effectsSignature = candidate && hasTypePredicateOrNeverReturnType(candidate) ? candidate : unknownSignature; + } + return signature === unknownSignature ? undefined : signature; + } + + function hasTypePredicateOrNeverReturnType(signature: Signature) { + return !!(getTypePredicateOfSignature(signature) || + signature.declaration && (getReturnTypeFromAnnotation(signature.declaration) || unknownType).flags & TypeFlags.Never); + } + + function getTypePredicateArgument(predicate: TypePredicate, callExpression: CallExpression) { + if (predicate.kind === TypePredicateKind.Identifier || predicate.kind === TypePredicateKind.AssertsIdentifier) { + return callExpression.arguments[predicate.parameterIndex]; + } + const invokedExpression = skipParentheses(callExpression.expression); + return isAccessExpression(invokedExpression) ? skipParentheses(invokedExpression.expression) : undefined; + } + + function reportFlowControlError(node: Node) { + const block = findAncestor(node, isFunctionOrModuleBlock) as Block | ModuleBlock | SourceFile; + const sourceFile = getSourceFileOfNode(node); + const span = getSpanOfTokenAtPosition(sourceFile, block.statements.pos); + diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.The_containing_function_or_module_body_is_too_large_for_control_flow_analysis)); + } + + function isReachableFlowNode(flow: FlowNode) { + const result = isReachableFlowNodeWorker(flow, /*noCacheCheck*/ false); + lastFlowNode = flow; + lastFlowNodeReachable = result; + return result; + } + + function isFalseExpression(expr: Expression): boolean { + const node = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + return node.kind === SyntaxKind.FalseKeyword || node.kind === SyntaxKind.BinaryExpression && ( + (node as BinaryExpression).operatorToken.kind === SyntaxKind.AmpersandAmpersandToken && (isFalseExpression((node as BinaryExpression).left) || isFalseExpression((node as BinaryExpression).right)) || + (node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken && isFalseExpression((node as BinaryExpression).left) && isFalseExpression((node as BinaryExpression).right) + ); + } + + function isReachableFlowNodeWorker(flow: FlowNode, noCacheCheck: boolean): boolean { + while (true) { + if (flow === lastFlowNode) { + return lastFlowNodeReachable; + } + const flags = flow.flags; + if (flags & FlowFlags.Shared) { + if (!noCacheCheck) { + const id = getFlowNodeId(flow); + const reachable = flowNodeReachable[id]; + return reachable !== undefined ? reachable : (flowNodeReachable[id] = isReachableFlowNodeWorker(flow, /*noCacheCheck*/ true)); + } + noCacheCheck = false; + } + if (flags & (FlowFlags.Assignment | FlowFlags.Condition | FlowFlags.ArrayMutation)) { + flow = (flow as FlowAssignment | FlowCondition | FlowArrayMutation).antecedent; + } + else if (flags & FlowFlags.Call) { + const signature = getEffectsSignature((flow as FlowCall).node); + if (signature) { + const predicate = getTypePredicateOfSignature(signature); + if (predicate && predicate.kind === TypePredicateKind.AssertsIdentifier && !predicate.type) { + const predicateArgument = (flow as FlowCall).node.arguments[predicate.parameterIndex]; + if (predicateArgument && isFalseExpression(predicateArgument)) { + return false; + } + } + if (getReturnTypeOfSignature(signature).flags & TypeFlags.Never) { + return false; + } + } + flow = (flow as FlowCall).antecedent; + } + else if (flags & FlowFlags.BranchLabel) { + // A branching point is reachable if any branch is reachable. + return some((flow as FlowLabel).antecedent, f => isReachableFlowNodeWorker(f, /*noCacheCheck*/ false)); + } + else if (flags & FlowFlags.LoopLabel) { + const antecedents = (flow as FlowLabel).antecedent; + if (antecedents === undefined || antecedents.length === 0) { + return false; + } + // A loop is reachable if the control flow path that leads to the top is reachable. + flow = antecedents[0]; + } + else if (flags & FlowFlags.SwitchClause) { + // The control flow path representing an unmatched value in a switch statement with + // no default clause is unreachable if the switch statement is exhaustive. + const data = (flow as FlowSwitchClause).node; + if (data.clauseStart === data.clauseEnd && isExhaustiveSwitchStatement(data.switchStatement)) { + return false; + } + flow = (flow as FlowSwitchClause).antecedent; + } + else if (flags & FlowFlags.ReduceLabel) { + // Cache is unreliable once we start adjusting labels + lastFlowNode = undefined; + const target = (flow as FlowReduceLabel).node.target; + const saveAntecedents = target.antecedent; + target.antecedent = (flow as FlowReduceLabel).node.antecedents; + const result = isReachableFlowNodeWorker((flow as FlowReduceLabel).antecedent, /*noCacheCheck*/ false); + target.antecedent = saveAntecedents; + return result; + } + else { + return !(flags & FlowFlags.Unreachable); + } + } + } + + // Return true if the given flow node is preceded by a 'super(...)' call in every possible code path + // leading to the node. + function isPostSuperFlowNode(flow: FlowNode, noCacheCheck: boolean): boolean { + while (true) { + const flags = flow.flags; + if (flags & FlowFlags.Shared) { + if (!noCacheCheck) { + const id = getFlowNodeId(flow); + const postSuper = flowNodePostSuper[id]; + return postSuper !== undefined ? postSuper : (flowNodePostSuper[id] = isPostSuperFlowNode(flow, /*noCacheCheck*/ true)); + } + noCacheCheck = false; + } + if (flags & (FlowFlags.Assignment | FlowFlags.Condition | FlowFlags.ArrayMutation | FlowFlags.SwitchClause)) { + flow = (flow as FlowAssignment | FlowCondition | FlowArrayMutation | FlowSwitchClause).antecedent; + } + else if (flags & FlowFlags.Call) { + if ((flow as FlowCall).node.expression.kind === SyntaxKind.SuperKeyword) { + return true; + } + flow = (flow as FlowCall).antecedent; + } + else if (flags & FlowFlags.BranchLabel) { + // A branching point is post-super if every branch is post-super. + return every((flow as FlowLabel).antecedent, f => isPostSuperFlowNode(f, /*noCacheCheck*/ false)); + } + else if (flags & FlowFlags.LoopLabel) { + // A loop is post-super if the control flow path that leads to the top is post-super. + flow = (flow as FlowLabel).antecedent![0]; + } + else if (flags & FlowFlags.ReduceLabel) { + const target = (flow as FlowReduceLabel).node.target; + const saveAntecedents = target.antecedent; + target.antecedent = (flow as FlowReduceLabel).node.antecedents; + const result = isPostSuperFlowNode((flow as FlowReduceLabel).antecedent, /*noCacheCheck*/ false); + target.antecedent = saveAntecedents; + return result; + } + else { + // Unreachable nodes are considered post-super to silence errors + return !!(flags & FlowFlags.Unreachable); + } + } + } + + function isConstantReference(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.ThisKeyword: + return true; + case SyntaxKind.Identifier: + if (!isThisInTypeQuery(node)) { + const symbol = getResolvedSymbol(node as Identifier); + return isConstantVariable(symbol) + || isParameterOrMutableLocalVariable(symbol) && !isSymbolAssigned(symbol) + || !!symbol.valueDeclaration && isFunctionExpression(symbol.valueDeclaration); + } + break; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + // The resolvedSymbol property is initialized by checkPropertyAccess or checkElementAccess before we get here. + return isConstantReference((node as AccessExpression).expression) && isReadonlySymbol(getNodeLinks(node).resolvedSymbol || unknownSymbol); + case SyntaxKind.ObjectBindingPattern: + case SyntaxKind.ArrayBindingPattern: + const rootDeclaration = getRootDeclaration(node.parent); + return isParameter(rootDeclaration) || isCatchClauseVariableDeclaration(rootDeclaration) + ? !isSomeSymbolAssigned(rootDeclaration) + : isVariableDeclaration(rootDeclaration) && isVarConstLike(rootDeclaration); + } + return false; + } + + function getFlowTypeOfReference(reference: Node, declaredType: Type, initialType = declaredType, flowContainer?: Node, flowNode = tryCast(reference, canHaveFlowNode)?.flowNode) { + let key: string | undefined; + let isKeySet = false; + let flowDepth = 0; + if (flowAnalysisDisabled) { + return errorType; + } + if (!flowNode) { + return declaredType; + } + flowInvocationCount++; + const sharedFlowStart = sharedFlowCount; + const evolvedType = getTypeFromFlowType(getTypeAtFlowNode(flowNode)); + sharedFlowCount = sharedFlowStart; + // When the reference is 'x' in an 'x.length', 'x.push(value)', 'x.unshift(value)' or x[n] = value' operation, + // we give type 'any[]' to 'x' instead of using the type determined by control flow analysis such that operations + // on empty arrays are possible without implicit any errors and new element types can be inferred without + // type mismatch errors. + const resultType = getObjectFlags(evolvedType) & ObjectFlags.EvolvingArray && isEvolvingArrayOperationTarget(reference) ? autoArrayType : finalizeEvolvingArrayType(evolvedType); + if (resultType === unreachableNeverType || reference.parent && reference.parent.kind === SyntaxKind.NonNullExpression && !(resultType.flags & TypeFlags.Never) && getTypeWithFacts(resultType, TypeFacts.NEUndefinedOrNull).flags & TypeFlags.Never) { + return declaredType; + } + return resultType; + + function getOrSetCacheKey() { + if (isKeySet) { + return key; + } + isKeySet = true; + return key = getFlowCacheKey(reference, declaredType, initialType, flowContainer); + } + + function getTypeAtFlowNode(flow: FlowNode): FlowType { + if (flowDepth === 2000) { + // We have made 2000 recursive invocations. To avoid overflowing the call stack we report an error + // and disable further control flow analysis in the containing function or module body. + tracing?.instant(tracing.Phase.CheckTypes, "getTypeAtFlowNode_DepthLimit", { flowId: flow.id }); + flowAnalysisDisabled = true; + reportFlowControlError(reference); + return errorType; + } + flowDepth++; + let sharedFlow: FlowNode | undefined; + while (true) { + const flags = flow.flags; + if (flags & FlowFlags.Shared) { + // We cache results of flow type resolution for shared nodes that were previously visited in + // the same getFlowTypeOfReference invocation. A node is considered shared when it is the + // antecedent of more than one node. + for (let i = sharedFlowStart; i < sharedFlowCount; i++) { + if (sharedFlowNodes[i] === flow) { + flowDepth--; + return sharedFlowTypes[i]; + } + } + sharedFlow = flow; + } + let type: FlowType | undefined; + if (flags & FlowFlags.Assignment) { + type = getTypeAtFlowAssignment(flow as FlowAssignment); + if (!type) { + flow = (flow as FlowAssignment).antecedent; + continue; + } + } + else if (flags & FlowFlags.Call) { + type = getTypeAtFlowCall(flow as FlowCall); + if (!type) { + flow = (flow as FlowCall).antecedent; + continue; + } + } + else if (flags & FlowFlags.Condition) { + type = getTypeAtFlowCondition(flow as FlowCondition); + } + else if (flags & FlowFlags.SwitchClause) { + type = getTypeAtSwitchClause(flow as FlowSwitchClause); + } + else if (flags & FlowFlags.Label) { + if ((flow as FlowLabel).antecedent!.length === 1) { + flow = (flow as FlowLabel).antecedent![0]; + continue; + } + type = flags & FlowFlags.BranchLabel ? + getTypeAtFlowBranchLabel(flow as FlowLabel) : + getTypeAtFlowLoopLabel(flow as FlowLabel); + } + else if (flags & FlowFlags.ArrayMutation) { + type = getTypeAtFlowArrayMutation(flow as FlowArrayMutation); + if (!type) { + flow = (flow as FlowArrayMutation).antecedent; + continue; + } + } + else if (flags & FlowFlags.ReduceLabel) { + const target = (flow as FlowReduceLabel).node.target; + const saveAntecedents = target.antecedent; + target.antecedent = (flow as FlowReduceLabel).node.antecedents; + type = getTypeAtFlowNode((flow as FlowReduceLabel).antecedent); + target.antecedent = saveAntecedents; + } + else if (flags & FlowFlags.Start) { + // Check if we should continue with the control flow of the containing function. + const container = (flow as FlowStart).node; + if ( + container && container !== flowContainer && + reference.kind !== SyntaxKind.PropertyAccessExpression && + reference.kind !== SyntaxKind.ElementAccessExpression && + !(reference.kind === SyntaxKind.ThisKeyword && container.kind !== SyntaxKind.ArrowFunction) + ) { + flow = container.flowNode!; + continue; + } + // At the top of the flow we have the initial type. + type = initialType; + } + else { + // Unreachable code errors are reported in the binding phase. Here we + // simply return the non-auto declared type to reduce follow-on errors. + type = convertAutoToAny(declaredType); + } + if (sharedFlow) { + // Record visited node and the associated type in the cache. + sharedFlowNodes[sharedFlowCount] = sharedFlow; + sharedFlowTypes[sharedFlowCount] = type; + sharedFlowCount++; + } + flowDepth--; + return type; + } + } + + function getInitialOrAssignedType(flow: FlowAssignment) { + const node = flow.node; + return getNarrowableTypeForReference( + node.kind === SyntaxKind.VariableDeclaration || node.kind === SyntaxKind.BindingElement ? + getInitialType(node as VariableDeclaration | BindingElement) : + getAssignedType(node), + reference, + ); + } + + function getTypeAtFlowAssignment(flow: FlowAssignment) { + const node = flow.node; + // Assignments only narrow the computed type if the declared type is a union type. Thus, we + // only need to evaluate the assigned type if the declared type is a union type. + if (isMatchingReference(reference, node)) { + if (!isReachableFlowNode(flow)) { + return unreachableNeverType; + } + if (getAssignmentTargetKind(node) === AssignmentKind.Compound) { + const flowType = getTypeAtFlowNode(flow.antecedent); + return createFlowType(getBaseTypeOfLiteralType(getTypeFromFlowType(flowType)), isIncomplete(flowType)); + } + if (declaredType === autoType || declaredType === autoArrayType) { + if (isEmptyArrayAssignment(node)) { + return getEvolvingArrayType(neverType); + } + const assignedType = getWidenedLiteralType(getInitialOrAssignedType(flow)); + return isTypeAssignableTo(assignedType, declaredType) ? assignedType : anyArrayType; + } + const t = isInCompoundLikeAssignment(node) ? getBaseTypeOfLiteralType(declaredType) : declaredType; + if (t.flags & TypeFlags.Union) { + return getAssignmentReducedType(t as UnionType, getInitialOrAssignedType(flow)); + } + return t; + } + // We didn't have a direct match. However, if the reference is a dotted name, this + // may be an assignment to a left hand part of the reference. For example, for a + // reference 'x.y.z', we may be at an assignment to 'x.y' or 'x'. In that case, + // return the declared type. + if (containsMatchingReference(reference, node)) { + if (!isReachableFlowNode(flow)) { + return unreachableNeverType; + } + // A matching dotted name might also be an expando property on a function *expression*, + // in which case we continue control flow analysis back to the function's declaration + if (isVariableDeclaration(node) && (isInJSFile(node) || isVarConstLike(node))) { + const init = getDeclaredExpandoInitializer(node); + if (init && (init.kind === SyntaxKind.FunctionExpression || init.kind === SyntaxKind.ArrowFunction)) { + return getTypeAtFlowNode(flow.antecedent); + } + } + return declaredType; + } + // for (const _ in ref) acts as a nonnull on ref + if ( + isVariableDeclaration(node) && + node.parent.parent.kind === SyntaxKind.ForInStatement && + (isMatchingReference(reference, node.parent.parent.expression) || optionalChainContainsReference(node.parent.parent.expression, reference)) + ) { + return getNonNullableTypeIfNeeded(finalizeEvolvingArrayType(getTypeFromFlowType(getTypeAtFlowNode(flow.antecedent)))); + } + // Assignment doesn't affect reference + return undefined; + } + + function narrowTypeByAssertion(type: Type, expr: Expression): Type { + const node = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + if (node.kind === SyntaxKind.FalseKeyword) { + return unreachableNeverType; + } + if (node.kind === SyntaxKind.BinaryExpression) { + if ((node as BinaryExpression).operatorToken.kind === SyntaxKind.AmpersandAmpersandToken) { + return narrowTypeByAssertion(narrowTypeByAssertion(type, (node as BinaryExpression).left), (node as BinaryExpression).right); + } + if ((node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken) { + return getUnionType([narrowTypeByAssertion(type, (node as BinaryExpression).left), narrowTypeByAssertion(type, (node as BinaryExpression).right)]); + } + } + return narrowType(type, node, /*assumeTrue*/ true); + } + + function getTypeAtFlowCall(flow: FlowCall): FlowType | undefined { + const signature = getEffectsSignature(flow.node); + if (signature) { + const predicate = getTypePredicateOfSignature(signature); + if (predicate && (predicate.kind === TypePredicateKind.AssertsThis || predicate.kind === TypePredicateKind.AssertsIdentifier)) { + const flowType = getTypeAtFlowNode(flow.antecedent); + const type = finalizeEvolvingArrayType(getTypeFromFlowType(flowType)); + const narrowedType = predicate.type ? narrowTypeByTypePredicate(type, predicate, flow.node, /*assumeTrue*/ true) : + predicate.kind === TypePredicateKind.AssertsIdentifier && predicate.parameterIndex >= 0 && predicate.parameterIndex < flow.node.arguments.length ? narrowTypeByAssertion(type, flow.node.arguments[predicate.parameterIndex]) : + type; + return narrowedType === type ? flowType : createFlowType(narrowedType, isIncomplete(flowType)); + } + if (getReturnTypeOfSignature(signature).flags & TypeFlags.Never) { + return unreachableNeverType; + } + } + return undefined; + } + + function getTypeAtFlowArrayMutation(flow: FlowArrayMutation): FlowType | undefined { + if (declaredType === autoType || declaredType === autoArrayType) { + const node = flow.node; + const expr = node.kind === SyntaxKind.CallExpression ? + (node.expression as PropertyAccessExpression).expression : + (node.left as ElementAccessExpression).expression; + if (isMatchingReference(reference, getReferenceCandidate(expr))) { + const flowType = getTypeAtFlowNode(flow.antecedent); + const type = getTypeFromFlowType(flowType); + if (getObjectFlags(type) & ObjectFlags.EvolvingArray) { + let evolvedType = type as EvolvingArrayType; + if (node.kind === SyntaxKind.CallExpression) { + for (const arg of node.arguments) { + evolvedType = addEvolvingArrayElementType(evolvedType, arg); + } + } + else { + // We must get the context free expression type so as to not recur in an uncached fashion on the LHS (which causes exponential blowup in compile time) + const indexType = getContextFreeTypeOfExpression((node.left as ElementAccessExpression).argumentExpression); + if (isTypeAssignableToKind(indexType, TypeFlags.NumberLike)) { + evolvedType = addEvolvingArrayElementType(evolvedType, node.right); + } + } + return evolvedType === type ? flowType : createFlowType(evolvedType, isIncomplete(flowType)); + } + return flowType; + } + } + return undefined; + } + + function getTypeAtFlowCondition(flow: FlowCondition): FlowType { + const flowType = getTypeAtFlowNode(flow.antecedent); + const type = getTypeFromFlowType(flowType); + if (type.flags & TypeFlags.Never) { + return flowType; + } + // If we have an antecedent type (meaning we're reachable in some way), we first + // attempt to narrow the antecedent type. If that produces the never type, and if + // the antecedent type is incomplete (i.e. a transient type in a loop), then we + // take the type guard as an indication that control *could* reach here once we + // have the complete type. We proceed by switching to the silent never type which + // doesn't report errors when operators are applied to it. Note that this is the + // *only* place a silent never type is ever generated. + const assumeTrue = (flow.flags & FlowFlags.TrueCondition) !== 0; + const nonEvolvingType = finalizeEvolvingArrayType(type); + const narrowedType = narrowType(nonEvolvingType, flow.node, assumeTrue); + if (narrowedType === nonEvolvingType) { + return flowType; + } + return createFlowType(narrowedType, isIncomplete(flowType)); + } + + function getTypeAtSwitchClause(flow: FlowSwitchClause): FlowType { + const expr = skipParentheses(flow.node.switchStatement.expression); + const flowType = getTypeAtFlowNode(flow.antecedent); + let type = getTypeFromFlowType(flowType); + if (isMatchingReference(reference, expr)) { + type = narrowTypeBySwitchOnDiscriminant(type, flow.node); + } + else if (expr.kind === SyntaxKind.TypeOfExpression && isMatchingReference(reference, (expr as TypeOfExpression).expression)) { + type = narrowTypeBySwitchOnTypeOf(type, flow.node); + } + else if (expr.kind === SyntaxKind.TrueKeyword) { + type = narrowTypeBySwitchOnTrue(type, flow.node); + } + else { + if (strictNullChecks) { + if (optionalChainContainsReference(expr, reference)) { + type = narrowTypeBySwitchOptionalChainContainment(type, flow.node, t => !(t.flags & (TypeFlags.Undefined | TypeFlags.Never))); + } + else if (expr.kind === SyntaxKind.TypeOfExpression && optionalChainContainsReference((expr as TypeOfExpression).expression, reference)) { + type = narrowTypeBySwitchOptionalChainContainment(type, flow.node, t => !(t.flags & TypeFlags.Never || t.flags & TypeFlags.StringLiteral && (t as StringLiteralType).value === "undefined")); + } + } + const access = getDiscriminantPropertyAccess(expr, type); + if (access) { + type = narrowTypeBySwitchOnDiscriminantProperty(type, access, flow.node); + } + } + return createFlowType(type, isIncomplete(flowType)); + } + + function getTypeAtFlowBranchLabel(flow: FlowLabel): FlowType { + const antecedentTypes: Type[] = []; + let subtypeReduction = false; + let seenIncomplete = false; + let bypassFlow: FlowSwitchClause | undefined; + for (const antecedent of flow.antecedent!) { + if (!bypassFlow && antecedent.flags & FlowFlags.SwitchClause && (antecedent as FlowSwitchClause).node.clauseStart === (antecedent as FlowSwitchClause).node.clauseEnd) { + // The antecedent is the bypass branch of a potentially exhaustive switch statement. + bypassFlow = antecedent as FlowSwitchClause; + continue; + } + const flowType = getTypeAtFlowNode(antecedent); + const type = getTypeFromFlowType(flowType); + // If the type at a particular antecedent path is the declared type and the + // reference is known to always be assigned (i.e. when declared and initial types + // are the same), there is no reason to process more antecedents since the only + // possible outcome is subtypes that will be removed in the final union type anyway. + if (type === declaredType && declaredType === initialType) { + return type; + } + pushIfUnique(antecedentTypes, type); + // If an antecedent type is not a subset of the declared type, we need to perform + // subtype reduction. This happens when a "foreign" type is injected into the control + // flow using the instanceof operator or a user defined type predicate. + if (!isTypeSubsetOf(type, initialType)) { + subtypeReduction = true; + } + if (isIncomplete(flowType)) { + seenIncomplete = true; + } + } + if (bypassFlow) { + const flowType = getTypeAtFlowNode(bypassFlow); + const type = getTypeFromFlowType(flowType); + // If the bypass flow contributes a type we haven't seen yet and the switch statement + // isn't exhaustive, process the bypass flow type. Since exhaustiveness checks increase + // the risk of circularities, we only want to perform them when they make a difference. + if (!(type.flags & TypeFlags.Never) && !contains(antecedentTypes, type) && !isExhaustiveSwitchStatement(bypassFlow.node.switchStatement)) { + if (type === declaredType && declaredType === initialType) { + return type; + } + antecedentTypes.push(type); + if (!isTypeSubsetOf(type, initialType)) { + subtypeReduction = true; + } + if (isIncomplete(flowType)) { + seenIncomplete = true; + } + } + } + return createFlowType(getUnionOrEvolvingArrayType(antecedentTypes, subtypeReduction ? UnionReduction.Subtype : UnionReduction.Literal), seenIncomplete); + } + + function getTypeAtFlowLoopLabel(flow: FlowLabel): FlowType { + // If we have previously computed the control flow type for the reference at + // this flow loop junction, return the cached type. + const id = getFlowNodeId(flow); + const cache = flowLoopCaches[id] || (flowLoopCaches[id] = new Map()); + const key = getOrSetCacheKey(); + if (!key) { + // No cache key is generated when binding patterns are in unnarrowable situations + return declaredType; + } + const cached = cache.get(key); + if (cached) { + return cached; + } + // If this flow loop junction and reference are already being processed, return + // the union of the types computed for each branch so far, marked as incomplete. + // It is possible to see an empty array in cases where loops are nested and the + // back edge of the outer loop reaches an inner loop that is already being analyzed. + // In such cases we restart the analysis of the inner loop, which will then see + // a non-empty in-process array for the outer loop and eventually terminate because + // the first antecedent of a loop junction is always the non-looping control flow + // path that leads to the top. + for (let i = flowLoopStart; i < flowLoopCount; i++) { + if (flowLoopNodes[i] === flow && flowLoopKeys[i] === key && flowLoopTypes[i].length) { + return createFlowType(getUnionOrEvolvingArrayType(flowLoopTypes[i], UnionReduction.Literal), /*incomplete*/ true); + } + } + // Add the flow loop junction and reference to the in-process stack and analyze + // each antecedent code path. + const antecedentTypes: Type[] = []; + let subtypeReduction = false; + let firstAntecedentType: FlowType | undefined; + for (const antecedent of flow.antecedent!) { + let flowType; + if (!firstAntecedentType) { + // The first antecedent of a loop junction is always the non-looping control + // flow path that leads to the top. + flowType = firstAntecedentType = getTypeAtFlowNode(antecedent); + } + else { + // All but the first antecedent are the looping control flow paths that lead + // back to the loop junction. We track these on the flow loop stack. + flowLoopNodes[flowLoopCount] = flow; + flowLoopKeys[flowLoopCount] = key; + flowLoopTypes[flowLoopCount] = antecedentTypes; + flowLoopCount++; + const saveFlowTypeCache = flowTypeCache; + flowTypeCache = undefined; + flowType = getTypeAtFlowNode(antecedent); + flowTypeCache = saveFlowTypeCache; + flowLoopCount--; + // If we see a value appear in the cache it is a sign that control flow analysis + // was restarted and completed by checkExpressionCached. We can simply pick up + // the resulting type and bail out. + const cached = cache.get(key); + if (cached) { + return cached; + } + } + const type = getTypeFromFlowType(flowType); + pushIfUnique(antecedentTypes, type); + // If an antecedent type is not a subset of the declared type, we need to perform + // subtype reduction. This happens when a "foreign" type is injected into the control + // flow using the instanceof operator or a user defined type predicate. + if (!isTypeSubsetOf(type, initialType)) { + subtypeReduction = true; + } + // If the type at a particular antecedent path is the declared type there is no + // reason to process more antecedents since the only possible outcome is subtypes + // that will be removed in the final union type anyway. + if (type === declaredType) { + break; + } + } + // The result is incomplete if the first antecedent (the non-looping control flow path) + // is incomplete. + const result = getUnionOrEvolvingArrayType(antecedentTypes, subtypeReduction ? UnionReduction.Subtype : UnionReduction.Literal); + if (isIncomplete(firstAntecedentType!)) { + return createFlowType(result, /*incomplete*/ true); + } + cache.set(key, result); + return result; + } + + // At flow control branch or loop junctions, if the type along every antecedent code path + // is an evolving array type, we construct a combined evolving array type. Otherwise we + // finalize all evolving array types. + function getUnionOrEvolvingArrayType(types: Type[], subtypeReduction: UnionReduction) { + if (isEvolvingArrayTypeList(types)) { + return getEvolvingArrayType(getUnionType(map(types, getElementTypeOfEvolvingArrayType))); + } + const result = recombineUnknownType(getUnionType(sameMap(types, finalizeEvolvingArrayType), subtypeReduction)); + if (result !== declaredType && result.flags & declaredType.flags & TypeFlags.Union && arraysEqual((result as UnionType).types, (declaredType as UnionType).types)) { + return declaredType; + } + return result; + } + + function getCandidateDiscriminantPropertyAccess(expr: Expression) { + if (isBindingPattern(reference) || isFunctionExpressionOrArrowFunction(reference) || isObjectLiteralMethod(reference)) { + // When the reference is a binding pattern or function or arrow expression, we are narrowing a pesudo-reference in + // getNarrowedTypeOfSymbol. An identifier for a destructuring variable declared in the same binding pattern or + // parameter declared in the same parameter list is a candidate. + if (isIdentifier(expr)) { + const symbol = getResolvedSymbol(expr); + const declaration = symbol.valueDeclaration; + if (declaration && (isBindingElement(declaration) || isParameter(declaration)) && reference === declaration.parent && !declaration.initializer && !declaration.dotDotDotToken) { + return declaration; + } + } + } + else if (isAccessExpression(expr)) { + // An access expression is a candidate if the reference matches the left hand expression. + if (isMatchingReference(reference, expr.expression)) { + return expr; + } + } + else if (isIdentifier(expr)) { + const symbol = getResolvedSymbol(expr); + if (isConstantVariable(symbol)) { + const declaration = symbol.valueDeclaration!; + // Given 'const x = obj.kind', allow 'x' as an alias for 'obj.kind' + if ( + isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && isAccessExpression(declaration.initializer) && + isMatchingReference(reference, declaration.initializer.expression) + ) { + return declaration.initializer; + } + // Given 'const { kind: x } = obj', allow 'x' as an alias for 'obj.kind' + if (isBindingElement(declaration) && !declaration.initializer) { + const parent = declaration.parent.parent; + if ( + isVariableDeclaration(parent) && !parent.type && parent.initializer && (isIdentifier(parent.initializer) || isAccessExpression(parent.initializer)) && + isMatchingReference(reference, parent.initializer) + ) { + return declaration; + } + } + } + } + return undefined; + } + + function getDiscriminantPropertyAccess(expr: Expression, computedType: Type) { + // As long as the computed type is a subset of the declared type, we use the full declared type to detect + // a discriminant property. In cases where the computed type isn't a subset, e.g because of a preceding type + // predicate narrowing, we use the actual computed type. + if (declaredType.flags & TypeFlags.Union || computedType.flags & TypeFlags.Union) { + const access = getCandidateDiscriminantPropertyAccess(expr); + if (access) { + const name = getAccessedPropertyName(access); + if (name) { + const type = declaredType.flags & TypeFlags.Union && isTypeSubsetOf(computedType, declaredType) ? declaredType : computedType; + if (isDiscriminantProperty(type, name)) { + return access; + } + } + } + } + return undefined; + } + + function narrowTypeByDiscriminant(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, narrowType: (t: Type) => Type): Type { + const propName = getAccessedPropertyName(access); + if (propName === undefined) { + return type; + } + const optionalChain = isOptionalChain(access); + const removeNullable = strictNullChecks && (optionalChain || isNonNullAccess(access)) && maybeTypeOfKind(type, TypeFlags.Nullable); + let propType = getTypeOfPropertyOfType(removeNullable ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type, propName); + if (!propType) { + return type; + } + propType = removeNullable && optionalChain ? getOptionalType(propType) : propType; + const narrowedPropType = narrowType(propType); + return filterType(type, t => { + const discriminantType = getTypeOfPropertyOrIndexSignatureOfType(t, propName) || unknownType; + return !(discriminantType.flags & TypeFlags.Never) && !(narrowedPropType.flags & TypeFlags.Never) && areTypesComparable(narrowedPropType, discriminantType); + }); + } + + function narrowTypeByDiscriminantProperty(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, operator: SyntaxKind, value: Expression, assumeTrue: boolean) { + if ((operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) && type.flags & TypeFlags.Union) { + const keyPropertyName = getKeyPropertyName(type as UnionType); + if (keyPropertyName && keyPropertyName === getAccessedPropertyName(access)) { + const candidate = getConstituentTypeForKeyType(type as UnionType, getTypeOfExpression(value)); + if (candidate) { + return operator === (assumeTrue ? SyntaxKind.EqualsEqualsEqualsToken : SyntaxKind.ExclamationEqualsEqualsToken) ? candidate : + isUnitType(getTypeOfPropertyOfType(candidate, keyPropertyName) || unknownType) ? removeType(type, candidate) : + type; + } + } + } + return narrowTypeByDiscriminant(type, access, t => narrowTypeByEquality(t, operator, value, assumeTrue)); + } + + function narrowTypeBySwitchOnDiscriminantProperty(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, data: FlowSwitchClauseData) { + if (data.clauseStart < data.clauseEnd && type.flags & TypeFlags.Union && getKeyPropertyName(type as UnionType) === getAccessedPropertyName(access)) { + const clauseTypes = getSwitchClauseTypes(data.switchStatement).slice(data.clauseStart, data.clauseEnd); + const candidate = getUnionType(map(clauseTypes, t => getConstituentTypeForKeyType(type as UnionType, t) || unknownType)); + if (candidate !== unknownType) { + return candidate; + } + } + return narrowTypeByDiscriminant(type, access, t => narrowTypeBySwitchOnDiscriminant(t, data)); + } + + function narrowTypeByTruthiness(type: Type, expr: Expression, assumeTrue: boolean): Type { + if (isMatchingReference(reference, expr)) { + return getAdjustedTypeWithFacts(type, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy); + } + if (strictNullChecks && assumeTrue && optionalChainContainsReference(expr, reference)) { + type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + const access = getDiscriminantPropertyAccess(expr, type); + if (access) { + return narrowTypeByDiscriminant(type, access, t => getTypeWithFacts(t, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy)); + } + return type; + } + + function isTypePresencePossible(type: Type, propName: __String, assumeTrue: boolean) { + const prop = getPropertyOfType(type, propName); + return prop ? + !!(prop.flags & SymbolFlags.Optional || getCheckFlags(prop) & CheckFlags.Partial) || assumeTrue : + !!getApplicableIndexInfoForName(type, propName) || !assumeTrue; + } + + function narrowTypeByInKeyword(type: Type, nameType: StringLiteralType | NumberLiteralType | UniqueESSymbolType, assumeTrue: boolean) { + const name = getPropertyNameFromType(nameType); + const isKnownProperty = someType(type, t => isTypePresencePossible(t, name, /*assumeTrue*/ true)); + if (isKnownProperty) { + // If the check is for a known property (i.e. a property declared in some constituent of + // the target type), we filter the target type by presence of absence of the property. + return filterType(type, t => isTypePresencePossible(t, name, assumeTrue)); + } + if (assumeTrue) { + // If the check is for an unknown property, we intersect the target type with `Record`, + // where X is the name of the property. + const recordSymbol = getGlobalRecordSymbol(); + if (recordSymbol) { + return getIntersectionType([type, getTypeAliasInstantiation(recordSymbol, [nameType, unknownType])]); + } + } + return type; + } + + function narrowTypeByBooleanComparison(type: Type, expr: Expression, bool: BooleanLiteral, operator: BinaryOperator, assumeTrue: boolean): Type { + assumeTrue = (assumeTrue !== (bool.kind === SyntaxKind.TrueKeyword)) !== (operator !== SyntaxKind.ExclamationEqualsEqualsToken && operator !== SyntaxKind.ExclamationEqualsToken); + return narrowType(type, expr, assumeTrue); + } + + function narrowTypeByBinaryExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type { + switch (expr.operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.BarBarEqualsToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: + case SyntaxKind.QuestionQuestionEqualsToken: + return narrowTypeByTruthiness(narrowType(type, expr.right, assumeTrue), expr.left, assumeTrue); + case SyntaxKind.EqualsEqualsToken: + case SyntaxKind.ExclamationEqualsToken: + case SyntaxKind.EqualsEqualsEqualsToken: + case SyntaxKind.ExclamationEqualsEqualsToken: + const operator = expr.operatorToken.kind; + const left = getReferenceCandidate(expr.left); + const right = getReferenceCandidate(expr.right); + if (left.kind === SyntaxKind.TypeOfExpression && isStringLiteralLike(right)) { + return narrowTypeByTypeof(type, left as TypeOfExpression, operator, right, assumeTrue); + } + if (right.kind === SyntaxKind.TypeOfExpression && isStringLiteralLike(left)) { + return narrowTypeByTypeof(type, right as TypeOfExpression, operator, left, assumeTrue); + } + if (isMatchingReference(reference, left)) { + return narrowTypeByEquality(type, operator, right, assumeTrue); + } + if (isMatchingReference(reference, right)) { + return narrowTypeByEquality(type, operator, left, assumeTrue); + } + if (strictNullChecks) { + if (optionalChainContainsReference(left, reference)) { + type = narrowTypeByOptionalChainContainment(type, operator, right, assumeTrue); + } + else if (optionalChainContainsReference(right, reference)) { + type = narrowTypeByOptionalChainContainment(type, operator, left, assumeTrue); + } + } + const leftAccess = getDiscriminantPropertyAccess(left, type); + if (leftAccess) { + return narrowTypeByDiscriminantProperty(type, leftAccess, operator, right, assumeTrue); + } + const rightAccess = getDiscriminantPropertyAccess(right, type); + if (rightAccess) { + return narrowTypeByDiscriminantProperty(type, rightAccess, operator, left, assumeTrue); + } + if (isMatchingConstructorReference(left)) { + return narrowTypeByConstructor(type, operator, right, assumeTrue); + } + if (isMatchingConstructorReference(right)) { + return narrowTypeByConstructor(type, operator, left, assumeTrue); + } + if (isBooleanLiteral(right) && !isAccessExpression(left)) { + return narrowTypeByBooleanComparison(type, left, right, operator, assumeTrue); + } + if (isBooleanLiteral(left) && !isAccessExpression(right)) { + return narrowTypeByBooleanComparison(type, right, left, operator, assumeTrue); + } + break; + case SyntaxKind.InstanceOfKeyword: + return narrowTypeByInstanceof(type, expr as InstanceofExpression, assumeTrue); + case SyntaxKind.InKeyword: + if (isPrivateIdentifier(expr.left)) { + return narrowTypeByPrivateIdentifierInInExpression(type, expr, assumeTrue); + } + const target = getReferenceCandidate(expr.right); + if (containsMissingType(type) && isAccessExpression(reference) && isMatchingReference(reference.expression, target)) { + const leftType = getTypeOfExpression(expr.left); + if (isTypeUsableAsPropertyName(leftType) && getAccessedPropertyName(reference) === getPropertyNameFromType(leftType)) { + return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined); + } + } + if (isMatchingReference(reference, target)) { + const leftType = getTypeOfExpression(expr.left); + if (isTypeUsableAsPropertyName(leftType)) { + return narrowTypeByInKeyword(type, leftType, assumeTrue); + } + } + break; + case SyntaxKind.CommaToken: + return narrowType(type, expr.right, assumeTrue); + // Ordinarily we won't see && and || expressions in control flow analysis because the Binder breaks those + // expressions down to individual conditional control flows. However, we may encounter them when analyzing + // aliased conditional expressions. + case SyntaxKind.AmpersandAmpersandToken: + return assumeTrue ? + narrowType(narrowType(type, expr.left, /*assumeTrue*/ true), expr.right, /*assumeTrue*/ true) : + getUnionType([narrowType(type, expr.left, /*assumeTrue*/ false), narrowType(type, expr.right, /*assumeTrue*/ false)]); + case SyntaxKind.BarBarToken: + return assumeTrue ? + getUnionType([narrowType(type, expr.left, /*assumeTrue*/ true), narrowType(type, expr.right, /*assumeTrue*/ true)]) : + narrowType(narrowType(type, expr.left, /*assumeTrue*/ false), expr.right, /*assumeTrue*/ false); + } + return type; + } + + function narrowTypeByPrivateIdentifierInInExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type { + const target = getReferenceCandidate(expr.right); + if (!isMatchingReference(reference, target)) { + return type; + } + + Debug.assertNode(expr.left, isPrivateIdentifier); + const symbol = getSymbolForPrivateIdentifierExpression(expr.left); + if (symbol === undefined) { + return type; + } + const classSymbol = symbol.parent!; + const targetType = hasStaticModifier(Debug.checkDefined(symbol.valueDeclaration, "should always have a declaration")) + ? getTypeOfSymbol(classSymbol) as InterfaceType + : getDeclaredTypeOfSymbol(classSymbol); + return getNarrowedType(type, targetType, assumeTrue, /*checkDerived*/ true); + } + + function narrowTypeByOptionalChainContainment(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type { + // We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows: + // When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch. + // When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch. + // When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch. + // When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch. + // When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch. + // When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch. + // When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch. + // When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch. + const equalsOperator = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken; + const nullableFlags = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken ? TypeFlags.Nullable : TypeFlags.Undefined; + const valueType = getTypeOfExpression(value); + // Note that we include any and unknown in the exclusion test because their domain includes null and undefined. + const removeNullable = equalsOperator !== assumeTrue && everyType(valueType, t => !!(t.flags & nullableFlags)) || + equalsOperator === assumeTrue && everyType(valueType, t => !(t.flags & (TypeFlags.AnyOrUnknown | nullableFlags))); + return removeNullable ? getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; + } + + function narrowTypeByEquality(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type { + if (type.flags & TypeFlags.Any) { + return type; + } + if (operator === SyntaxKind.ExclamationEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) { + assumeTrue = !assumeTrue; + } + const valueType = getTypeOfExpression(value); + const doubleEquals = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken; + if (valueType.flags & TypeFlags.Nullable) { + if (!strictNullChecks) { + return type; + } + const facts = doubleEquals ? + assumeTrue ? TypeFacts.EQUndefinedOrNull : TypeFacts.NEUndefinedOrNull : + valueType.flags & TypeFlags.Null ? + assumeTrue ? TypeFacts.EQNull : TypeFacts.NENull : + assumeTrue ? TypeFacts.EQUndefined : TypeFacts.NEUndefined; + return getAdjustedTypeWithFacts(type, facts); + } + if (assumeTrue) { + if (!doubleEquals && (type.flags & TypeFlags.Unknown || someType(type, isEmptyAnonymousObjectType))) { + if (valueType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive) || isEmptyAnonymousObjectType(valueType)) { + return valueType; + } + if (valueType.flags & TypeFlags.Object) { + return nonPrimitiveType; + } + } + const filteredType = filterType(type, t => areTypesComparable(t, valueType) || doubleEquals && isCoercibleUnderDoubleEquals(t, valueType)); + return replacePrimitivesWithLiterals(filteredType, valueType); + } + if (isUnitType(valueType)) { + return filterType(type, t => !(isUnitLikeType(t) && areTypesComparable(t, valueType))); + } + return type; + } + + function narrowTypeByTypeof(type: Type, typeOfExpr: TypeOfExpression, operator: SyntaxKind, literal: LiteralExpression, assumeTrue: boolean): Type { + // We have '==', '!=', '===', or !==' operator with 'typeof xxx' and string literal operands + if (operator === SyntaxKind.ExclamationEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) { + assumeTrue = !assumeTrue; + } + const target = getReferenceCandidate(typeOfExpr.expression); + if (!isMatchingReference(reference, target)) { + if (strictNullChecks && optionalChainContainsReference(target, reference) && assumeTrue === (literal.text !== "undefined")) { + type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + const propertyAccess = getDiscriminantPropertyAccess(target, type); + if (propertyAccess) { + return narrowTypeByDiscriminant(type, propertyAccess, t => narrowTypeByLiteralExpression(t, literal, assumeTrue)); + } + return type; + } + return narrowTypeByLiteralExpression(type, literal, assumeTrue); + } + + function narrowTypeByLiteralExpression(type: Type, literal: LiteralExpression, assumeTrue: boolean) { + return assumeTrue ? + narrowTypeByTypeName(type, literal.text) : + getAdjustedTypeWithFacts(type, typeofNEFacts.get(literal.text) || TypeFacts.TypeofNEHostObject); + } + + function narrowTypeBySwitchOptionalChainContainment(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData, clauseCheck: (type: Type) => boolean) { + const everyClauseChecks = clauseStart !== clauseEnd && every(getSwitchClauseTypes(switchStatement).slice(clauseStart, clauseEnd), clauseCheck); + return everyClauseChecks ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; + } + + function narrowTypeBySwitchOnDiscriminant(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData) { + // We only narrow if all case expressions specify + // values with unit types, except for the case where + // `type` is unknown. In this instance we map object + // types to the nonPrimitive type and narrow with that. + const switchTypes = getSwitchClauseTypes(switchStatement); + if (!switchTypes.length) { + return type; + } + const clauseTypes = switchTypes.slice(clauseStart, clauseEnd); + const hasDefaultClause = clauseStart === clauseEnd || contains(clauseTypes, neverType); + if ((type.flags & TypeFlags.Unknown) && !hasDefaultClause) { + let groundClauseTypes: Type[] | undefined; + for (let i = 0; i < clauseTypes.length; i += 1) { + const t = clauseTypes[i]; + if (t.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive)) { + if (groundClauseTypes !== undefined) { + groundClauseTypes.push(t); + } + } + else if (t.flags & TypeFlags.Object) { + if (groundClauseTypes === undefined) { + groundClauseTypes = clauseTypes.slice(0, i); + } + groundClauseTypes.push(nonPrimitiveType); + } + else { + return type; + } + } + return getUnionType(groundClauseTypes === undefined ? clauseTypes : groundClauseTypes); + } + const discriminantType = getUnionType(clauseTypes); + const caseType = discriminantType.flags & TypeFlags.Never ? neverType : + replacePrimitivesWithLiterals(filterType(type, t => areTypesComparable(discriminantType, t)), discriminantType); + if (!hasDefaultClause) { + return caseType; + } + const defaultType = filterType(type, t => !(isUnitLikeType(t) && contains(switchTypes, t.flags & TypeFlags.Undefined ? undefinedType : getRegularTypeOfLiteralType(extractUnitType(t))))); + return caseType.flags & TypeFlags.Never ? defaultType : getUnionType([caseType, defaultType]); + } + + function narrowTypeByTypeName(type: Type, typeName: string) { + switch (typeName) { + case "string": + return narrowTypeByTypeFacts(type, stringType, TypeFacts.TypeofEQString); + case "number": + return narrowTypeByTypeFacts(type, numberType, TypeFacts.TypeofEQNumber); + case "bigint": + return narrowTypeByTypeFacts(type, bigintType, TypeFacts.TypeofEQBigInt); + case "boolean": + return narrowTypeByTypeFacts(type, booleanType, TypeFacts.TypeofEQBoolean); + case "symbol": + return narrowTypeByTypeFacts(type, esSymbolType, TypeFacts.TypeofEQSymbol); + case "object": + return type.flags & TypeFlags.Any ? type : getUnionType([narrowTypeByTypeFacts(type, nonPrimitiveType, TypeFacts.TypeofEQObject), narrowTypeByTypeFacts(type, nullType, TypeFacts.EQNull)]); + case "function": + return type.flags & TypeFlags.Any ? type : narrowTypeByTypeFacts(type, globalFunctionType, TypeFacts.TypeofEQFunction); + case "undefined": + return narrowTypeByTypeFacts(type, undefinedType, TypeFacts.EQUndefined); + } + return narrowTypeByTypeFacts(type, nonPrimitiveType, TypeFacts.TypeofEQHostObject); + } + + function narrowTypeByTypeFacts(type: Type, impliedType: Type, facts: TypeFacts) { + return mapType(type, t => + // We first check if a constituent is a subtype of the implied type. If so, we either keep or eliminate + // the constituent based on its type facts. We use the strict subtype relation because it treats `object` + // as a subtype of `{}`, and we need the type facts check because function types are subtypes of `object`, + // but are classified as "function" according to `typeof`. + isTypeRelatedTo(t, impliedType, strictSubtypeRelation) ? hasTypeFacts(t, facts) ? t : neverType : + // We next check if the consituent is a supertype of the implied type. If so, we substitute the implied + // type. This handles top types like `unknown` and `{}`, and supertypes like `{ toString(): string }`. + isTypeSubtypeOf(impliedType, t) ? impliedType : + // Neither the constituent nor the implied type is a subtype of the other, however their domains may still + // overlap. For example, an unconstrained type parameter and type `string`. If the type facts indicate + // possible overlap, we form an intersection. Otherwise, we eliminate the constituent. + hasTypeFacts(t, facts) ? getIntersectionType([t, impliedType]) : + neverType); + } + + function narrowTypeBySwitchOnTypeOf(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData): Type { + const witnesses = getSwitchClauseTypeOfWitnesses(switchStatement); + if (!witnesses) { + return type; + } + // Equal start and end denotes implicit fallthrough; undefined marks explicit default clause. + const defaultIndex = findIndex(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.DefaultClause); + const hasDefaultClause = clauseStart === clauseEnd || (defaultIndex >= clauseStart && defaultIndex < clauseEnd); + if (hasDefaultClause) { + // In the default clause we filter constituents down to those that are not-equal to all handled cases. + const notEqualFacts = getNotEqualFactsFromTypeofSwitch(clauseStart, clauseEnd, witnesses); + return filterType(type, t => getTypeFacts(t, notEqualFacts) === notEqualFacts); + } + // In the non-default cause we create a union of the type narrowed by each of the listed cases. + const clauseWitnesses = witnesses.slice(clauseStart, clauseEnd); + return getUnionType(map(clauseWitnesses, text => text ? narrowTypeByTypeName(type, text) : neverType)); + } + + function narrowTypeBySwitchOnTrue(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData): Type { + const defaultIndex = findIndex(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.DefaultClause); + const hasDefaultClause = clauseStart === clauseEnd || (defaultIndex >= clauseStart && defaultIndex < clauseEnd); + + // First, narrow away all of the cases that preceded this set of cases. + for (let i = 0; i < clauseStart; i++) { + const clause = switchStatement.caseBlock.clauses[i]; + if (clause.kind === SyntaxKind.CaseClause) { + type = narrowType(type, clause.expression, /*assumeTrue*/ false); + } + } + + // If our current set has a default, then none the other cases were hit either. + // There's no point in narrowing by the the other cases in the set, since we can + // get here through other paths. + if (hasDefaultClause) { + for (let i = clauseEnd; i < switchStatement.caseBlock.clauses.length; i++) { + const clause = switchStatement.caseBlock.clauses[i]; + if (clause.kind === SyntaxKind.CaseClause) { + type = narrowType(type, clause.expression, /*assumeTrue*/ false); + } + } + return type; + } + + // Now, narrow based on the cases in this set. + const clauses = switchStatement.caseBlock.clauses.slice(clauseStart, clauseEnd); + return getUnionType(map(clauses, clause => clause.kind === SyntaxKind.CaseClause ? narrowType(type, clause.expression, /*assumeTrue*/ true) : neverType)); + } + + function isMatchingConstructorReference(expr: Expression) { + return (isPropertyAccessExpression(expr) && idText(expr.name) === "constructor" || + isElementAccessExpression(expr) && isStringLiteralLike(expr.argumentExpression) && expr.argumentExpression.text === "constructor") && + isMatchingReference(reference, expr.expression); + } + + function narrowTypeByConstructor(type: Type, operator: SyntaxKind, identifier: Expression, assumeTrue: boolean): Type { + // Do not narrow when checking inequality. + if (assumeTrue ? (operator !== SyntaxKind.EqualsEqualsToken && operator !== SyntaxKind.EqualsEqualsEqualsToken) : (operator !== SyntaxKind.ExclamationEqualsToken && operator !== SyntaxKind.ExclamationEqualsEqualsToken)) { + return type; + } + + // Get the type of the constructor identifier expression, if it is not a function then do not narrow. + const identifierType = getTypeOfExpression(identifier); + if (!isFunctionType(identifierType) && !isConstructorType(identifierType)) { + return type; + } + + // Get the prototype property of the type identifier so we can find out its type. + const prototypeProperty = getPropertyOfType(identifierType, "prototype" as __String); + if (!prototypeProperty) { + return type; + } + + // Get the type of the prototype, if it is undefined, or the global `Object` or `Function` types then do not narrow. + const prototypeType = getTypeOfSymbol(prototypeProperty); + const candidate = !isTypeAny(prototypeType) ? prototypeType : undefined; + if (!candidate || candidate === globalObjectType || candidate === globalFunctionType) { + return type; + } + + // If the type that is being narrowed is `any` then just return the `candidate` type since every type is a subtype of `any`. + if (isTypeAny(type)) { + return candidate; + } + + // Filter out types that are not considered to be "constructed by" the `candidate` type. + return filterType(type, t => isConstructedBy(t, candidate)); + + function isConstructedBy(source: Type, target: Type) { + // If either the source or target type are a class type then we need to check that they are the same exact type. + // This is because you may have a class `A` that defines some set of properties, and another class `B` + // that defines the same set of properties as class `A`, in that case they are structurally the same + // type, but when you do something like `instanceOfA.constructor === B` it will return false. + if ( + source.flags & TypeFlags.Object && getObjectFlags(source) & ObjectFlags.Class || + target.flags & TypeFlags.Object && getObjectFlags(target) & ObjectFlags.Class + ) { + return source.symbol === target.symbol; + } + + // For all other types just check that the `source` type is a subtype of the `target` type. + return isTypeSubtypeOf(source, target); + } + } + + function narrowTypeByInstanceof(type: Type, expr: InstanceofExpression, assumeTrue: boolean): Type { + const left = getReferenceCandidate(expr.left); + if (!isMatchingReference(reference, left)) { + if (assumeTrue && strictNullChecks && optionalChainContainsReference(left, reference)) { + return getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + return type; + } + const right = expr.right; + const rightType = getTypeOfExpression(right); + if (!isTypeDerivedFrom(rightType, globalObjectType)) { + return type; + } + + // if the right-hand side has an object type with a custom `[Symbol.hasInstance]` method, and that method + // has a type predicate, use the type predicate to perform narrowing. This allows normal `object` types to + // participate in `instanceof`, as per Step 2 of https://tc39.es/ecma262/#sec-instanceofoperator. + const signature = getEffectsSignature(expr); + const predicate = signature && getTypePredicateOfSignature(signature); + if (predicate && predicate.kind === TypePredicateKind.Identifier && predicate.parameterIndex === 0) { + return getNarrowedType(type, predicate.type, assumeTrue, /*checkDerived*/ true); + } + if (!isTypeDerivedFrom(rightType, globalFunctionType)) { + return type; + } + const instanceType = mapType(rightType, getInstanceType); + // Don't narrow from `any` if the target type is exactly `Object` or `Function`, and narrow + // in the false branch only if the target is a non-empty object type. + if ( + isTypeAny(type) && (instanceType === globalObjectType || instanceType === globalFunctionType) || + !assumeTrue && !(instanceType.flags & TypeFlags.Object && !isEmptyAnonymousObjectType(instanceType)) + ) { + return type; + } + return getNarrowedType(type, instanceType, assumeTrue, /*checkDerived*/ true); + } + + function getInstanceType(constructorType: Type) { + const prototypePropertyType = getTypeOfPropertyOfType(constructorType, "prototype" as __String); + if (prototypePropertyType && !isTypeAny(prototypePropertyType)) { + return prototypePropertyType; + } + const constructSignatures = getSignaturesOfType(constructorType, SignatureKind.Construct); + if (constructSignatures.length) { + return getUnionType(map(constructSignatures, signature => getReturnTypeOfSignature(getErasedSignature(signature)))); + } + // We use the empty object type to indicate we don't know the type of objects created by + // this constructor function. + return emptyObjectType; + } + + function getNarrowedType(type: Type, candidate: Type, assumeTrue: boolean, checkDerived: boolean): Type { + const key = type.flags & TypeFlags.Union ? `N${getTypeId(type)},${getTypeId(candidate)},${(assumeTrue ? 1 : 0) | (checkDerived ? 2 : 0)}` : undefined; + return getCachedType(key) ?? setCachedType(key, getNarrowedTypeWorker(type, candidate, assumeTrue, checkDerived)); + } + + function getNarrowedTypeWorker(type: Type, candidate: Type, assumeTrue: boolean, checkDerived: boolean) { + if (!assumeTrue) { + if (type === candidate) { + return neverType; + } + if (checkDerived) { + return filterType(type, t => !isTypeDerivedFrom(t, candidate)); + } + const trueType = getNarrowedType(type, candidate, /*assumeTrue*/ true, /*checkDerived*/ false); + return filterType(type, t => !isTypeSubsetOf(t, trueType)); + } + if (type.flags & TypeFlags.AnyOrUnknown) { + return candidate; + } + if (type === candidate) { + return candidate; + } + + // We first attempt to filter the current type, narrowing constituents as appropriate and removing + // constituents that are unrelated to the candidate. + const isRelated = checkDerived ? isTypeDerivedFrom : isTypeSubtypeOf; + const keyPropertyName = type.flags & TypeFlags.Union ? getKeyPropertyName(type as UnionType) : undefined; + const narrowedType = mapType(candidate, c => { + // If a discriminant property is available, use that to reduce the type. + const discriminant = keyPropertyName && getTypeOfPropertyOfType(c, keyPropertyName); + const matching = discriminant && getConstituentTypeForKeyType(type as UnionType, discriminant); + // For each constituent t in the current type, if t and and c are directly related, pick the most + // specific of the two. When t and c are related in both directions, we prefer c for type predicates + // because that is the asserted type, but t for `instanceof` because generics aren't reflected in + // prototype object types. + const directlyRelated = mapType( + matching || type, + checkDerived ? + t => isTypeDerivedFrom(t, c) ? t : isTypeDerivedFrom(c, t) ? c : neverType : + t => isTypeStrictSubtypeOf(t, c) ? t : isTypeStrictSubtypeOf(c, t) ? c : isTypeSubtypeOf(t, c) ? t : isTypeSubtypeOf(c, t) ? c : neverType, + ); + // If no constituents are directly related, create intersections for any generic constituents that + // are related by constraint. + return directlyRelated.flags & TypeFlags.Never ? + mapType(type, t => maybeTypeOfKind(t, TypeFlags.Instantiable) && isRelated(c, getBaseConstraintOfType(t) || unknownType) ? getIntersectionType([t, c]) : neverType) : + directlyRelated; + }); + // If filtering produced a non-empty type, return that. Otherwise, pick the most specific of the two + // based on assignability, or as a last resort produce an intersection. + return !(narrowedType.flags & TypeFlags.Never) ? narrowedType : + isTypeSubtypeOf(candidate, type) ? candidate : + isTypeAssignableTo(type, candidate) ? type : + isTypeAssignableTo(candidate, type) ? candidate : + getIntersectionType([type, candidate]); + } + + function narrowTypeByCallExpression(type: Type, callExpression: CallExpression, assumeTrue: boolean): Type { + if (hasMatchingArgument(callExpression, reference)) { + const signature = assumeTrue || !isCallChain(callExpression) ? getEffectsSignature(callExpression) : undefined; + const predicate = signature && getTypePredicateOfSignature(signature); + if (predicate && (predicate.kind === TypePredicateKind.This || predicate.kind === TypePredicateKind.Identifier)) { + return narrowTypeByTypePredicate(type, predicate, callExpression, assumeTrue); + } + } + if (containsMissingType(type) && isAccessExpression(reference) && isPropertyAccessExpression(callExpression.expression)) { + const callAccess = callExpression.expression; + if ( + isMatchingReference(reference.expression, getReferenceCandidate(callAccess.expression)) && + isIdentifier(callAccess.name) && callAccess.name.escapedText === "hasOwnProperty" && callExpression.arguments.length === 1 + ) { + const argument = callExpression.arguments[0]; + if (isStringLiteralLike(argument) && getAccessedPropertyName(reference) === escapeLeadingUnderscores(argument.text)) { + return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined); + } + } + } + return type; + } + + function narrowTypeByTypePredicate(type: Type, predicate: TypePredicate, callExpression: CallExpression, assumeTrue: boolean): Type { + // Don't narrow from 'any' if the predicate type is exactly 'Object' or 'Function' + if (predicate.type && !(isTypeAny(type) && (predicate.type === globalObjectType || predicate.type === globalFunctionType))) { + const predicateArgument = getTypePredicateArgument(predicate, callExpression); + if (predicateArgument) { + if (isMatchingReference(reference, predicateArgument)) { + return getNarrowedType(type, predicate.type, assumeTrue, /*checkDerived*/ false); + } + if ( + strictNullChecks && optionalChainContainsReference(predicateArgument, reference) && + ( + assumeTrue && !(hasTypeFacts(predicate.type, TypeFacts.EQUndefined)) || + !assumeTrue && everyType(predicate.type, isNullableType) + ) + ) { + type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + const access = getDiscriminantPropertyAccess(predicateArgument, type); + if (access) { + return narrowTypeByDiscriminant(type, access, t => getNarrowedType(t, predicate.type!, assumeTrue, /*checkDerived*/ false)); + } + } + } + return type; + } + + // Narrow the given type based on the given expression having the assumed boolean value. The returned type + // will be a subtype or the same type as the argument. + function narrowType(type: Type, expr: Expression, assumeTrue: boolean): Type { + // for `a?.b`, we emulate a synthetic `a !== null && a !== undefined` condition for `a` + if ( + isExpressionOfOptionalChainRoot(expr) || + isBinaryExpression(expr.parent) && (expr.parent.operatorToken.kind === SyntaxKind.QuestionQuestionToken || expr.parent.operatorToken.kind === SyntaxKind.QuestionQuestionEqualsToken) && expr.parent.left === expr + ) { + return narrowTypeByOptionality(type, expr, assumeTrue); + } + switch (expr.kind) { + case SyntaxKind.Identifier: + // When narrowing a reference to a const variable, non-assigned parameter, or readonly property, we inline + // up to five levels of aliased conditional expressions that are themselves declared as const variables. + if (!isMatchingReference(reference, expr) && inlineLevel < 5) { + const symbol = getResolvedSymbol(expr as Identifier); + if (isConstantVariable(symbol)) { + const declaration = symbol.valueDeclaration; + if (declaration && isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && isConstantReference(reference)) { + inlineLevel++; + const result = narrowType(type, declaration.initializer, assumeTrue); + inlineLevel--; + return result; + } + } + } + // falls through + case SyntaxKind.ThisKeyword: + case SyntaxKind.SuperKeyword: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + return narrowTypeByTruthiness(type, expr, assumeTrue); + case SyntaxKind.CallExpression: + return narrowTypeByCallExpression(type, expr as CallExpression, assumeTrue); + case SyntaxKind.ParenthesizedExpression: + case SyntaxKind.NonNullExpression: + return narrowType(type, (expr as ParenthesizedExpression | NonNullExpression).expression, assumeTrue); + case SyntaxKind.BinaryExpression: + return narrowTypeByBinaryExpression(type, expr as BinaryExpression, assumeTrue); + case SyntaxKind.PrefixUnaryExpression: + if ((expr as PrefixUnaryExpression).operator === SyntaxKind.ExclamationToken) { + return narrowType(type, (expr as PrefixUnaryExpression).operand, !assumeTrue); + } + break; + } + return type; + } + + function narrowTypeByOptionality(type: Type, expr: Expression, assumePresent: boolean): Type { + if (isMatchingReference(reference, expr)) { + return getAdjustedTypeWithFacts(type, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull); + } + const access = getDiscriminantPropertyAccess(expr, type); + if (access) { + return narrowTypeByDiscriminant(type, access, t => getTypeWithFacts(t, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull)); + } + return type; + } + } + + function getTypeOfSymbolAtLocation(symbol: Symbol, location: Node) { + symbol = getExportSymbolOfValueSymbolIfExported(symbol); + + // If we have an identifier or a property access at the given location, if the location is + // an dotted name expression, and if the location is not an assignment target, obtain the type + // of the expression (which will reflect control flow analysis). If the expression indeed + // resolved to the given symbol, return the narrowed type. + if (location.kind === SyntaxKind.Identifier || location.kind === SyntaxKind.PrivateIdentifier) { + if (isRightSideOfQualifiedNameOrPropertyAccess(location)) { + location = location.parent; + } + if (isExpressionNode(location) && (!isAssignmentTarget(location) || isWriteAccess(location))) { + const type = removeOptionalTypeMarker( + isWriteAccess(location) && location.kind === SyntaxKind.PropertyAccessExpression ? + checkPropertyAccessExpression(location as PropertyAccessExpression, /*checkMode*/ undefined, /*writeOnly*/ true) : + getTypeOfExpression(location as Expression), + ); + if (getExportSymbolOfValueSymbolIfExported(getNodeLinks(location).resolvedSymbol) === symbol) { + return type; + } + } + } + if (isDeclarationName(location) && isSetAccessor(location.parent) && getAnnotatedAccessorTypeNode(location.parent)) { + return getWriteTypeOfAccessors(location.parent.symbol); + } + // The location isn't a reference to the given symbol, meaning we're being asked + // a hypothetical question of what type the symbol would have if there was a reference + // to it at the given location. Since we have no control flow information for the + // hypothetical reference (control flow information is created and attached by the + // binder), we simply return the declared type of the symbol. + return isRightSideOfAccessExpression(location) && isWriteAccess(location.parent) ? getWriteTypeOfSymbol(symbol) : getNonMissingTypeOfSymbol(symbol); + } + + function getControlFlowContainer(node: Node): Node { + return findAncestor(node.parent, node => + isFunctionLike(node) && !getImmediatelyInvokedFunctionExpression(node) || + node.kind === SyntaxKind.ModuleBlock || + node.kind === SyntaxKind.SourceFile || + node.kind === SyntaxKind.PropertyDeclaration)!; + } + + // Check if a parameter or catch variable is assigned anywhere + function isSymbolAssigned(symbol: Symbol) { + return !isPastLastAssignment(symbol, /*location*/ undefined); + } + + // Return true if there are no assignments to the given symbol or if the given location + // is past the last assignment to the symbol. + function isPastLastAssignment(symbol: Symbol, location: Node | undefined) { + const parent = findAncestor(symbol.valueDeclaration, isFunctionOrSourceFile); + if (!parent) { + return false; + } + const links = getNodeLinks(parent); + if (!(links.flags & NodeCheckFlags.AssignmentsMarked)) { + links.flags |= NodeCheckFlags.AssignmentsMarked; + if (!hasParentWithAssignmentsMarked(parent)) { + markNodeAssignments(parent); + } + } + return !symbol.lastAssignmentPos || location && symbol.lastAssignmentPos < location.pos; + } + + // Check if a parameter or catch variable (or their bindings elements) is assigned anywhere + function isSomeSymbolAssigned(rootDeclaration: Node) { + Debug.assert(isVariableDeclaration(rootDeclaration) || isParameter(rootDeclaration)); + return isSomeSymbolAssignedWorker(rootDeclaration.name); + } + + function isSomeSymbolAssignedWorker(node: BindingName): boolean { + if (node.kind === SyntaxKind.Identifier) { + return isSymbolAssigned(getSymbolOfDeclaration(node.parent as Declaration)); + } + + return some(node.elements, e => e.kind !== SyntaxKind.OmittedExpression && isSomeSymbolAssignedWorker(e.name)); + } + + function hasParentWithAssignmentsMarked(node: Node) { + return !!findAncestor(node.parent, node => isFunctionOrSourceFile(node) && !!(getNodeLinks(node).flags & NodeCheckFlags.AssignmentsMarked)); + } + + function isFunctionOrSourceFile(node: Node) { + return isFunctionLikeDeclaration(node) || isSourceFile(node); + } + + // For all assignments within the given root node, record the last assignment source position for all + // referenced parameters and mutable local variables. When assignments occur in nested functions or + // references occur in export specifiers, record Number.MAX_VALUE as the assignment position. When + // assignments occur in compound statements, record the ending source position of the compound statement + // as the assignment position (this is more conservative than full control flow analysis, but requires + // only a single walk over the AST). + function markNodeAssignments(node: Node) { + switch (node.kind) { + case SyntaxKind.Identifier: + if (isAssignmentTarget(node)) { + const symbol = getResolvedSymbol(node as Identifier); + if (isParameterOrMutableLocalVariable(symbol) && symbol.lastAssignmentPos !== Number.MAX_VALUE) { + const referencingFunction = findAncestor(node, isFunctionOrSourceFile); + const declaringFunction = findAncestor(symbol.valueDeclaration, isFunctionOrSourceFile); + symbol.lastAssignmentPos = referencingFunction === declaringFunction ? extendAssignmentPosition(node, symbol.valueDeclaration!) : Number.MAX_VALUE; + } + } + return; + case SyntaxKind.ExportSpecifier: + const exportDeclaration = (node as ExportSpecifier).parent.parent; + const name = (node as ExportSpecifier).propertyName || (node as ExportSpecifier).name; + if (!(node as ExportSpecifier).isTypeOnly && !exportDeclaration.isTypeOnly && !exportDeclaration.moduleSpecifier && name.kind !== SyntaxKind.StringLiteral) { + const symbol = resolveEntityName(name, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ true); + if (symbol && isParameterOrMutableLocalVariable(symbol)) { + symbol.lastAssignmentPos = Number.MAX_VALUE; + } + } + return; + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.EnumDeclaration: + return; + } + if (isTypeNode(node)) { + return; + } + forEachChild(node, markNodeAssignments); + } + + // Extend the position of the given assignment target node to the end of any intervening variable statement, + // expression statement, compound statement, or class declaration occurring between the node and the given + // declaration node. + function extendAssignmentPosition(node: Node, declaration: Declaration) { + let pos = node.pos; + while (node && node.pos > declaration.pos) { + switch (node.kind) { + case SyntaxKind.VariableStatement: + case SyntaxKind.ExpressionStatement: + case SyntaxKind.IfStatement: + case SyntaxKind.DoStatement: + case SyntaxKind.WhileStatement: + case SyntaxKind.ForStatement: + case SyntaxKind.ForInStatement: + case SyntaxKind.ForOfStatement: + case SyntaxKind.WithStatement: + case SyntaxKind.SwitchStatement: + case SyntaxKind.TryStatement: + case SyntaxKind.ClassDeclaration: + pos = node.end; + } + node = node.parent; + } + return pos; + } + + function isConstantVariable(symbol: Symbol) { + return symbol.flags & SymbolFlags.Variable && (getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Constant) !== 0; + } + + function isParameterOrMutableLocalVariable(symbol: Symbol) { + // Return true if symbol is a parameter, a catch clause variable, or a mutable local variable + const declaration = symbol.valueDeclaration && getRootDeclaration(symbol.valueDeclaration); + return !!declaration && ( + isParameter(declaration) || + isVariableDeclaration(declaration) && (isCatchClause(declaration.parent) || isMutableLocalVariableDeclaration(declaration)) + ); + } + + function isMutableLocalVariableDeclaration(declaration: VariableDeclaration) { + // Return true if symbol is a non-exported and non-global `let` variable + return !!(declaration.parent.flags & NodeFlags.Let) && !( + getCombinedModifierFlags(declaration) & ModifierFlags.Export || + declaration.parent.parent.kind === SyntaxKind.VariableStatement && isGlobalSourceFile(declaration.parent.parent.parent) + ); + } + + function parameterInitializerContainsUndefined(declaration: ParameterDeclaration): boolean { + const links = getNodeLinks(declaration); + + if (links.parameterInitializerContainsUndefined === undefined) { + if (!pushTypeResolution(declaration, TypeSystemPropertyName.ParameterInitializerContainsUndefined)) { + reportCircularityError(declaration.symbol); + return true; + } + + const containsUndefined = !!(hasTypeFacts(checkDeclarationInitializer(declaration, CheckMode.Normal), TypeFacts.IsUndefined)); + + if (!popTypeResolution()) { + reportCircularityError(declaration.symbol); + return true; + } + + links.parameterInitializerContainsUndefined ??= containsUndefined; + } + + return links.parameterInitializerContainsUndefined; + } + + /** remove undefined from the annotated type of a parameter when there is an initializer (that doesn't include undefined) */ + function removeOptionalityFromDeclaredType(declaredType: Type, declaration: VariableLikeDeclaration): Type { + const removeUndefined = strictNullChecks && + declaration.kind === SyntaxKind.Parameter && + declaration.initializer && + hasTypeFacts(declaredType, TypeFacts.IsUndefined) && + !parameterInitializerContainsUndefined(declaration); + + return removeUndefined ? getTypeWithFacts(declaredType, TypeFacts.NEUndefined) : declaredType; + } + + function isConstraintPosition(type: Type, node: Node) { + const parent = node.parent; + // In an element access obj[x], we consider obj to be in a constraint position, except when obj is of + // a generic type without a nullable constraint and x is a generic type. This is because when both obj + // and x are of generic types T and K, we want the resulting type to be T[K]. + return parent.kind === SyntaxKind.PropertyAccessExpression || + parent.kind === SyntaxKind.QualifiedName || + parent.kind === SyntaxKind.CallExpression && (parent as CallExpression).expression === node || + parent.kind === SyntaxKind.NewExpression && (parent as NewExpression).expression === node || + parent.kind === SyntaxKind.ElementAccessExpression && (parent as ElementAccessExpression).expression === node && + !(someType(type, isGenericTypeWithoutNullableConstraint) && isGenericIndexType(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression))); + } + + function isGenericTypeWithUnionConstraint(type: Type): boolean { + return type.flags & TypeFlags.Intersection ? + some((type as IntersectionType).types, isGenericTypeWithUnionConstraint) : + !!(type.flags & TypeFlags.Instantiable && getBaseConstraintOrType(type).flags & (TypeFlags.Nullable | TypeFlags.Union)); + } + + function isGenericTypeWithoutNullableConstraint(type: Type): boolean { + return type.flags & TypeFlags.Intersection ? + some((type as IntersectionType).types, isGenericTypeWithoutNullableConstraint) : + !!(type.flags & TypeFlags.Instantiable && !maybeTypeOfKind(getBaseConstraintOrType(type), TypeFlags.Nullable)); + } + + function hasContextualTypeWithNoGenericTypes(node: Node, checkMode: CheckMode | undefined) { + // Computing the contextual type for a child of a JSX element involves resolving the type of the + // element's tag name, so we exclude that here to avoid circularities. + // If check mode has `CheckMode.RestBindingElement`, we skip binding pattern contextual types, + // as we want the type of a rest element to be generic when possible. + const contextualType = (isIdentifier(node) || isPropertyAccessExpression(node) || isElementAccessExpression(node)) && + !((isJsxOpeningElement(node.parent) || isJsxSelfClosingElement(node.parent)) && node.parent.tagName === node) && + (checkMode && checkMode & CheckMode.RestBindingElement ? + getContextualType(node, ContextFlags.SkipBindingPatterns) + : getContextualType(node, /*contextFlags*/ undefined)); + return contextualType && !isGenericType(contextualType); + } + + function getNarrowableTypeForReference(type: Type, reference: Node, checkMode?: CheckMode) { + if (isNoInferType(type)) { + type = (type as SubstitutionType).baseType; + } + // When the type of a reference is or contains an instantiable type with a union type constraint, and + // when the reference is in a constraint position (where it is known we'll obtain the apparent type) or + // has a contextual type containing no top-level instantiables (meaning constraints will determine + // assignability), we substitute constraints for all instantiables in the type of the reference to give + // control flow analysis an opportunity to narrow it further. For example, for a reference of a type + // parameter type 'T extends string | undefined' with a contextual type 'string', we substitute + // 'string | undefined' to give control flow analysis the opportunity to narrow to type 'string'. + const substituteConstraints = !(checkMode && checkMode & CheckMode.Inferential) && + someType(type, isGenericTypeWithUnionConstraint) && + (isConstraintPosition(type, reference) || hasContextualTypeWithNoGenericTypes(reference, checkMode)); + return substituteConstraints ? mapType(type, getBaseConstraintOrType) : type; + } + + function isExportOrExportExpression(location: Node) { + return !!findAncestor(location, n => { + const parent = n.parent; + if (parent === undefined) { + return "quit"; + } + if (isExportAssignment(parent)) { + return parent.expression === n && isEntityNameExpression(n); + } + if (isExportSpecifier(parent)) { + return parent.name === n || parent.propertyName === n; + } + return false; + }); + } + + /** + * This function marks all the imports the given location refers to as `.referenced` in `NodeLinks` (transitively through local import aliases). + * (This corresponds to not getting elided in JS emit.) + * It can be called on *most* nodes in the AST with `ReferenceHint.Unspecified` and will filter its inputs, but care should be taken to avoid calling it on the RHS of an `import =` or specifiers in a `import {} from "..."`, + * unless you *really* want to *definitely* mark those as referenced. + * These shouldn't be directly marked, and should only get marked transitively by the internals of this function. + * + * @param location The location to mark js import refernces for + * @param hint The kind of reference `location` has already been checked to be + * @param propSymbol The optional symbol of the property we're looking up - this is used for property accesses when `const enum`s do not count as references (no `isolatedModules`, no `preserveConstEnums` + export). It will be calculated if not provided. + * @param parentType The optional type of the parent of the LHS of the property access - this will be recalculated if not provided (but is costly). + */ + function markLinkedReferences(location: PropertyAccessExpression | QualifiedName, hint: ReferenceHint.Property, propSymbol: Symbol | undefined, parentType: Type): void; + function markLinkedReferences(location: Identifier, hint: ReferenceHint.Identifier): void; + function markLinkedReferences(location: ExportAssignment, hint: ReferenceHint.ExportAssignment): void; + function markLinkedReferences(location: JsxOpeningLikeElement | JsxOpeningFragment, hint: ReferenceHint.Jsx): void; + function markLinkedReferences(location: FunctionLikeDeclaration | MethodSignature, hint: ReferenceHint.AsyncFunction): void; + function markLinkedReferences(location: ImportEqualsDeclaration, hint: ReferenceHint.ExportImportEquals): void; + function markLinkedReferences(location: ExportSpecifier, hint: ReferenceHint.ExportSpecifier): void; + function markLinkedReferences(location: HasDecorators, hint: ReferenceHint.Decorator): void; + function markLinkedReferences(location: Node, hint: ReferenceHint.Unspecified, propSymbol?: Symbol, parentType?: Type): void; + function markLinkedReferences(location: Node, hint: ReferenceHint, propSymbol?: Symbol, parentType?: Type) { + if (!canCollectSymbolAliasAccessabilityData) { + return; + } + if (location.flags & NodeFlags.Ambient) { + return; // References within types and declaration files are never going to contribute to retaining a JS import + } + switch (hint) { + case ReferenceHint.Identifier: + return markIdentifierAliasReferenced(location as Identifier); + case ReferenceHint.Property: + return markPropertyAliasReferenced(location as PropertyAccessExpression | QualifiedName, propSymbol, parentType); + case ReferenceHint.ExportAssignment: + return markExportAssignmentAliasReferenced(location as ExportAssignment); + case ReferenceHint.Jsx: + return markJsxAliasReferenced(location as JsxOpeningLikeElement | JsxOpeningFragment); + case ReferenceHint.AsyncFunction: + return markAsyncFunctionAliasReferenced(location as FunctionLikeDeclaration | MethodSignature); + case ReferenceHint.ExportImportEquals: + return markImportEqualsAliasReferenced(location as ImportEqualsDeclaration); + case ReferenceHint.ExportSpecifier: + return markExportSpecifierAliasReferenced(location as ExportSpecifier); + case ReferenceHint.Decorator: + return markDecoratorAliasReferenced(location as HasDecorators); + case ReferenceHint.Unspecified: { + // Identifiers in expression contexts are emitted, so we need to follow their referenced aliases and mark them as used + // Some non-expression identifiers are also treated as expression identifiers for this purpose, eg, `a` in `b = {a}` or `q` in `import r = q` + // This is the exception, rather than the rule - most non-expression identifiers are declaration names. + if (isIdentifier(location) && (isExpressionNode(location) || isShorthandPropertyAssignment(location.parent) || (isImportEqualsDeclaration(location.parent) && location.parent.moduleReference === location)) && shouldMarkIdentifierAliasReferenced(location)) { + if (isPropertyAccessOrQualifiedName(location.parent)) { + const left = isPropertyAccessExpression(location.parent) ? location.parent.expression : location.parent.left; + if (left !== location) return; // Only mark the LHS (the RHS is a property lookup) + } + markIdentifierAliasReferenced(location); + return; + } + if (isPropertyAccessOrQualifiedName(location)) { + let topProp: Node | undefined = location; + while (isPropertyAccessOrQualifiedName(topProp)) { + if (isPartOfTypeNode(topProp)) return; + topProp = topProp.parent; + } + return markPropertyAliasReferenced(location); + } + if (isExportAssignment(location)) { + return markExportAssignmentAliasReferenced(location); + } + if (isJsxOpeningLikeElement(location) || isJsxOpeningFragment(location)) { + return markJsxAliasReferenced(location); + } + if (isImportEqualsDeclaration(location)) { + if (isInternalModuleImportEqualsDeclaration(location) || checkExternalImportOrExportDeclaration(location)) { + return markImportEqualsAliasReferenced(location); + } + return; + } + if (isExportSpecifier(location)) { + return markExportSpecifierAliasReferenced(location); + } + if (isFunctionLikeDeclaration(location) || isMethodSignature(location)) { + markAsyncFunctionAliasReferenced(location); + // Might be decorated, fall through to decorator final case + } + if (!compilerOptions.emitDecoratorMetadata) { + return; + } + if (!canHaveDecorators(location) || !hasDecorators(location) || !location.modifiers || !nodeCanBeDecorated(legacyDecorators, location, location.parent, location.parent.parent)) { + return; + } + + return markDecoratorAliasReferenced(location); + } + default: + Debug.assertNever(hint, `Unhandled reference hint: ${hint}`); + } + } + + function markIdentifierAliasReferenced(location: Identifier) { + const symbol = getResolvedSymbol(location); + if (symbol && symbol !== argumentsSymbol && symbol !== unknownSymbol && !isThisInTypeQuery(location)) { + markAliasReferenced(symbol, location); + } + } + + function markPropertyAliasReferenced(location: PropertyAccessExpression | QualifiedName, propSymbol?: Symbol, parentType?: Type) { + const left = isPropertyAccessExpression(location) ? location.expression : location.left; + if (isThisIdentifier(left) || !isIdentifier(left)) { + return; + } + const parentSymbol = getResolvedSymbol(left); + if (!parentSymbol || parentSymbol === unknownSymbol) { + return; + } + // In `Foo.Bar.Baz`, 'Foo' is not referenced if 'Bar' is a const enum or a module containing only const enums. + // `Foo` is also not referenced in `enum FooCopy { Bar = Foo.Bar }`, because the enum member value gets inlined + // here even if `Foo` is not a const enum. + // + // The exceptions are: + // 1. if 'isolatedModules' is enabled, because the const enum value will not be inlined, and + // 2. if 'preserveConstEnums' is enabled and the expression is itself an export, e.g. `export = Foo.Bar.Baz`. + // + // The property lookup is deferred as much as possible, in as many situations as possible, to avoid alias marking + // pulling on types/symbols it doesn't strictly need to. + if (getIsolatedModules(compilerOptions) || (shouldPreserveConstEnums(compilerOptions) && isExportOrExportExpression(location))) { + markAliasReferenced(parentSymbol, location); + return; + } + // Hereafter, this relies on type checking - but every check prior to this only used symbol information + const leftType = parentType || checkExpressionCached(left); + if (isTypeAny(leftType) || leftType === silentNeverType) { + markAliasReferenced(parentSymbol, location); + return; + } + let prop = propSymbol; + if (!prop && !parentType) { + const right = isPropertyAccessExpression(location) ? location.name : location.right; + const lexicallyScopedSymbol = isPrivateIdentifier(right) && lookupSymbolForPrivateIdentifierDeclaration(right.escapedText, right); + const assignmentKind = getAssignmentTargetKind(location); + const apparentType = getApparentType(assignmentKind !== AssignmentKind.None || isMethodAccessForCall(location) ? getWidenedType(leftType) : leftType); + prop = isPrivateIdentifier(right) ? lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(apparentType, lexicallyScopedSymbol) || undefined : getPropertyOfType(apparentType, right.escapedText); + } + if ( + !(prop && (isConstEnumOrConstEnumOnlyModule(prop) || prop.flags & SymbolFlags.EnumMember && location.parent.kind === SyntaxKind.EnumMember)) + ) { + markAliasReferenced(parentSymbol, location); + } + return; + } + + function markExportAssignmentAliasReferenced(location: ExportAssignment) { + if (isIdentifier(location.expression)) { + const id = location.expression; + const sym = getExportSymbolOfValueSymbolIfExported(resolveEntityName(id, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location)); + if (sym) { + markAliasReferenced(sym, id); + } + } + } + + function markJsxAliasReferenced(node: JsxOpeningLikeElement | JsxOpeningFragment) { + if (!getJsxNamespaceContainerForImplicitImport(node)) { + // The reactNamespace/jsxFactory's root symbol should be marked as 'used' so we don't incorrectly elide its import. + // And if there is no reactNamespace/jsxFactory's symbol in scope when targeting React emit, we should issue an error. + const jsxFactoryRefErr = diagnostics && compilerOptions.jsx === JsxEmit.React ? Diagnostics.Cannot_find_name_0 : undefined; + const jsxFactoryNamespace = getJsxNamespace(node); + const jsxFactoryLocation = isJsxOpeningLikeElement(node) ? node.tagName : node; + + // allow null as jsxFragmentFactory + let jsxFactorySym: Symbol | undefined; + if (!(isJsxOpeningFragment(node) && jsxFactoryNamespace === "null")) { + jsxFactorySym = resolveName(jsxFactoryLocation, jsxFactoryNamespace, SymbolFlags.Value, jsxFactoryRefErr, /*isUse*/ true); + } + + if (jsxFactorySym) { + // Mark local symbol as referenced here because it might not have been marked + // if jsx emit was not jsxFactory as there wont be error being emitted + jsxFactorySym.isReferenced = SymbolFlags.All; + + // If react/jsxFactory symbol is alias, mark it as refereced + if (canCollectSymbolAliasAccessabilityData && jsxFactorySym.flags & SymbolFlags.Alias && !getTypeOnlyAliasDeclaration(jsxFactorySym)) { + markAliasSymbolAsReferenced(jsxFactorySym); + } + } + + // For JsxFragment, mark jsx pragma as referenced via resolveName + if (isJsxOpeningFragment(node)) { + const file = getSourceFileOfNode(node); + const localJsxNamespace = getLocalJsxNamespace(file); + if (localJsxNamespace) { + resolveName(jsxFactoryLocation, localJsxNamespace, SymbolFlags.Value, jsxFactoryRefErr, /*isUse*/ true); + } + } + } + return; + } + + function markAsyncFunctionAliasReferenced(location: FunctionLikeDeclaration | MethodSignature) { + if (languageVersion < ScriptTarget.ES2015) { + if (getFunctionFlags(location) & FunctionFlags.Async) { + const returnTypeNode = getEffectiveReturnTypeNode(location); + markTypeNodeAsReferenced(returnTypeNode); + } + } + } + + function markImportEqualsAliasReferenced(location: ImportEqualsDeclaration) { + if (hasSyntacticModifier(location, ModifierFlags.Export)) { + markExportAsReferenced(location); + } + } + + function markExportSpecifierAliasReferenced(location: ExportSpecifier) { + if (!location.parent.parent.moduleSpecifier && !location.isTypeOnly && !location.parent.parent.isTypeOnly) { + const exportedName = location.propertyName || location.name; + if (exportedName.kind === SyntaxKind.StringLiteral) { + return; // Skip for invalid syntax like this: export { "x" } + } + const symbol = resolveName(exportedName, exportedName.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (symbol && (symbol === undefinedSymbol || symbol === globalThisSymbol || symbol.declarations && isGlobalSourceFile(getDeclarationContainer(symbol.declarations[0])))) { + // Do nothing, non-local symbol + } + else { + const target = symbol && (symbol.flags & SymbolFlags.Alias ? resolveAlias(symbol) : symbol); + if (!target || getSymbolFlags(target) & SymbolFlags.Value) { + markExportAsReferenced(location); // marks export as used + markIdentifierAliasReferenced(exportedName); // marks target of export as used + } + } + return; + } + } + + function markDecoratorAliasReferenced(node: HasDecorators) { + if (compilerOptions.emitDecoratorMetadata) { + const firstDecorator = find(node.modifiers, isDecorator); + if (!firstDecorator) { + return; + } + + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Metadata); + + // we only need to perform these checks if we are emitting serialized type metadata for the target of a decorator. + switch (node.kind) { + case SyntaxKind.ClassDeclaration: + const constructor = getFirstConstructorWithBody(node); + if (constructor) { + for (const parameter of constructor.parameters) { + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); + } + } + break; + + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + const otherKind = node.kind === SyntaxKind.GetAccessor ? SyntaxKind.SetAccessor : SyntaxKind.GetAccessor; + const otherAccessor = getDeclarationOfKind(getSymbolOfDeclaration(node), otherKind); + markDecoratorMedataDataTypeNodeAsReferenced(getAnnotatedAccessorTypeNode(node) || otherAccessor && getAnnotatedAccessorTypeNode(otherAccessor)); + break; + case SyntaxKind.MethodDeclaration: + for (const parameter of node.parameters) { + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); + } + + markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveReturnTypeNode(node)); + break; + + case SyntaxKind.PropertyDeclaration: + markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveTypeAnnotationNode(node)); + break; + + case SyntaxKind.Parameter: + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(node)); + const containingSignature = node.parent; + for (const parameter of containingSignature.parameters) { + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); + } + markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveReturnTypeNode(containingSignature)); + break; + } + } + } + + function markAliasReferenced(symbol: Symbol, location: Node) { + if (!canCollectSymbolAliasAccessabilityData) { + return; + } + if (isNonLocalAlias(symbol, /*excludes*/ SymbolFlags.Value) && !isInTypeQuery(location)) { + const target = resolveAlias(symbol); + if (getSymbolFlags(symbol, /*excludeTypeOnlyMeanings*/ true) & (SymbolFlags.Value | SymbolFlags.ExportValue)) { + // An alias resolving to a const enum cannot be elided if (1) 'isolatedModules' is enabled + // (because the const enum value will not be inlined), or if (2) the alias is an export + // of a const enum declaration that will be preserved. + if ( + getIsolatedModules(compilerOptions) || + shouldPreserveConstEnums(compilerOptions) && isExportOrExportExpression(location) || + !isConstEnumOrConstEnumOnlyModule(getExportSymbolOfValueSymbolIfExported(target)) + ) { + markAliasSymbolAsReferenced(symbol); + } + } + } + } + + // When an alias symbol is referenced, we need to mark the entity it references as referenced and in turn repeat that until + // we reach a non-alias or an exported entity (which is always considered referenced). We do this by checking the target of + // the alias as an expression (which recursively takes us back here if the target references another alias). + function markAliasSymbolAsReferenced(symbol: Symbol) { + Debug.assert(canCollectSymbolAliasAccessabilityData); + const links = getSymbolLinks(symbol); + if (!links.referenced) { + links.referenced = true; + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + // We defer checking of the reference of an `import =` until the import itself is referenced, + // This way a chain of imports can be elided if ultimately the final input is only used in a type + // position. + if (isInternalModuleImportEqualsDeclaration(node)) { + if (getSymbolFlags(resolveSymbol(symbol)) & SymbolFlags.Value) { + // import foo = + const left = getFirstIdentifier(node.moduleReference as EntityNameExpression); + markIdentifierAliasReferenced(left); + } + } + } + } + + function markExportAsReferenced(node: ImportEqualsDeclaration | ExportSpecifier) { + const symbol = getSymbolOfDeclaration(node); + const target = resolveAlias(symbol); + if (target) { + const markAlias = target === unknownSymbol || + ((getSymbolFlags(symbol, /*excludeTypeOnlyMeanings*/ true) & SymbolFlags.Value) && !isConstEnumOrConstEnumOnlyModule(target)); + + if (markAlias) { + markAliasSymbolAsReferenced(symbol); + } + } + } + + function markEntityNameOrEntityExpressionAsReference(typeName: EntityNameOrEntityNameExpression | undefined, forDecoratorMetadata: boolean) { + if (!typeName) return; + + const rootName = getFirstIdentifier(typeName); + const meaning = (typeName.kind === SyntaxKind.Identifier ? SymbolFlags.Type : SymbolFlags.Namespace) | SymbolFlags.Alias; + const rootSymbol = resolveName(rootName, rootName.escapedText, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (rootSymbol && rootSymbol.flags & SymbolFlags.Alias) { + if ( + canCollectSymbolAliasAccessabilityData + && symbolIsValue(rootSymbol) + && !isConstEnumOrConstEnumOnlyModule(resolveAlias(rootSymbol)) + && !getTypeOnlyAliasDeclaration(rootSymbol) + ) { + markAliasSymbolAsReferenced(rootSymbol); + } + else if ( + forDecoratorMetadata + && getIsolatedModules(compilerOptions) + && getEmitModuleKind(compilerOptions) >= ModuleKind.ES2015 + && !symbolIsValue(rootSymbol) + && !some(rootSymbol.declarations, isTypeOnlyImportOrExportDeclaration) + ) { + const diag = error(typeName, Diagnostics.A_type_referenced_in_a_decorated_signature_must_be_imported_with_import_type_or_a_namespace_import_when_isolatedModules_and_emitDecoratorMetadata_are_enabled); + const aliasDeclaration = find(rootSymbol.declarations || emptyArray, isAliasSymbolDeclaration); + if (aliasDeclaration) { + addRelatedInfo(diag, createDiagnosticForNode(aliasDeclaration, Diagnostics._0_was_imported_here, idText(rootName))); + } + } + } + } + + /** + * If a TypeNode can be resolved to a value symbol imported from an external module, it is + * marked as referenced to prevent import elision. + */ + function markTypeNodeAsReferenced(node: TypeNode | undefined) { + markEntityNameOrEntityExpressionAsReference(node && getEntityNameFromTypeNode(node), /*forDecoratorMetadata*/ false); + } + + /** + * This function marks the type used for metadata decorator as referenced if it is import + * from external module. + * This is different from markTypeNodeAsReferenced because it tries to simplify type nodes in + * union and intersection type + * @param node + */ + function markDecoratorMedataDataTypeNodeAsReferenced(node: TypeNode | undefined): void { + const entityName = getEntityNameForDecoratorMetadata(node); + if (entityName && isEntityName(entityName)) { + markEntityNameOrEntityExpressionAsReference(entityName, /*forDecoratorMetadata*/ true); + } + } + + function getNarrowedTypeOfSymbol(symbol: Symbol, location: Identifier, checkMode?: CheckMode) { + const type = getTypeOfSymbol(symbol, checkMode); + const declaration = symbol.valueDeclaration; + if (declaration) { + // If we have a non-rest binding element with no initializer declared as a const variable or a const-like + // parameter (a parameter for which there are no assignments in the function body), and if the parent type + // for the destructuring is a union type, one or more of the binding elements may represent discriminant + // properties, and we want the effects of conditional checks on such discriminants to affect the types of + // other binding elements from the same destructuring. Consider: + // + // type Action = + // | { kind: 'A', payload: number } + // | { kind: 'B', payload: string }; + // + // function f({ kind, payload }: Action) { + // if (kind === 'A') { + // payload.toFixed(); + // } + // if (kind === 'B') { + // payload.toUpperCase(); + // } + // } + // + // Above, we want the conditional checks on 'kind' to affect the type of 'payload'. To facilitate this, we use + // the binding pattern AST instance for '{ kind, payload }' as a pseudo-reference and narrow this reference + // as if it occurred in the specified location. We then recompute the narrowed binding element type by + // destructuring from the narrowed parent type. + if (isBindingElement(declaration) && !declaration.initializer && !declaration.dotDotDotToken && declaration.parent.elements.length >= 2) { + const parent = declaration.parent.parent; + const rootDeclaration = getRootDeclaration(parent); + if (rootDeclaration.kind === SyntaxKind.VariableDeclaration && getCombinedNodeFlagsCached(rootDeclaration) & NodeFlags.Constant || rootDeclaration.kind === SyntaxKind.Parameter) { + const links = getNodeLinks(parent); + if (!(links.flags & NodeCheckFlags.InCheckIdentifier)) { + links.flags |= NodeCheckFlags.InCheckIdentifier; + const parentType = getTypeForBindingElementParent(parent, CheckMode.Normal); + const parentTypeConstraint = parentType && mapType(parentType, getBaseConstraintOrType); + links.flags &= ~NodeCheckFlags.InCheckIdentifier; + if (parentTypeConstraint && parentTypeConstraint.flags & TypeFlags.Union && !(rootDeclaration.kind === SyntaxKind.Parameter && isSomeSymbolAssigned(rootDeclaration))) { + const pattern = declaration.parent; + const narrowedType = getFlowTypeOfReference(pattern, parentTypeConstraint, parentTypeConstraint, /*flowContainer*/ undefined, location.flowNode); + if (narrowedType.flags & TypeFlags.Never) { + return neverType; + } + // Destructurings are validated against the parent type elsewhere. Here we disable tuple bounds + // checks because the narrowed type may have lower arity than the full parent type. For example, + // for the declaration [x, y]: [1, 2] | [3], we may have narrowed the parent type to just [3]. + return getBindingElementTypeFromParentType(declaration, narrowedType, /*noTupleBoundsCheck*/ true); + } + } + } + } + // If we have a const-like parameter with no type annotation or initializer, and if the parameter is contextually + // typed by a signature with a single rest parameter of a union of tuple types, one or more of the parameters may + // represent discriminant tuple elements, and we want the effects of conditional checks on such discriminants to + // affect the types of other parameters in the same parameter list. Consider: + // + // type Action = [kind: 'A', payload: number] | [kind: 'B', payload: string]; + // + // const f: (...args: Action) => void = (kind, payload) => { + // if (kind === 'A') { + // payload.toFixed(); + // } + // if (kind === 'B') { + // payload.toUpperCase(); + // } + // } + // + // Above, we want the conditional checks on 'kind' to affect the type of 'payload'. To facilitate this, we use + // the arrow function AST node for '(kind, payload) => ...' as a pseudo-reference and narrow this reference as + // if it occurred in the specified location. We then recompute the narrowed parameter type by indexing into the + // narrowed tuple type. + if (isParameter(declaration) && !declaration.type && !declaration.initializer && !declaration.dotDotDotToken) { + const func = declaration.parent; + if (func.parameters.length >= 2 && isContextSensitiveFunctionOrObjectLiteralMethod(func)) { + const contextualSignature = getContextualSignature(func); + if (contextualSignature && contextualSignature.parameters.length === 1 && signatureHasRestParameter(contextualSignature)) { + const restType = getReducedApparentType(instantiateType(getTypeOfSymbol(contextualSignature.parameters[0]), getInferenceContext(func)?.nonFixingMapper)); + if (restType.flags & TypeFlags.Union && everyType(restType, isTupleType) && !some(func.parameters, isSomeSymbolAssigned)) { + const narrowedType = getFlowTypeOfReference(func, restType, restType, /*flowContainer*/ undefined, location.flowNode); + const index = func.parameters.indexOf(declaration) - (getThisParameter(func) ? 1 : 0); + return getIndexedAccessType(narrowedType, getNumberLiteralType(index)); + } + } + } + } + } + return type; + } + + /** + * This part of `checkIdentifier` is kept seperate from the rest, so `NodeCheckFlags` (and related diagnostics) can be lazily calculated + * without calculating the flow type of the identifier. + */ + function checkIdentifierCalculateNodeCheckFlags(node: Identifier, symbol: Symbol) { + if (isThisInTypeQuery(node)) return; + + // As noted in ECMAScript 6 language spec, arrow functions never have an arguments objects. + // Although in down-level emit of arrow function, we emit it using function expression which means that + // arguments objects will be bound to the inner object; emitting arrow function natively in ES6, arguments objects + // will be bound to non-arrow function that contain this arrow function. This results in inconsistent behavior. + // To avoid that we will give an error to users if they use arguments objects in arrow function so that they + // can explicitly bound arguments objects + if (symbol === argumentsSymbol) { + if (isInPropertyInitializerOrClassStaticBlock(node)) { + error(node, Diagnostics.arguments_cannot_be_referenced_in_property_initializers); + return; + } + + let container = getContainingFunction(node); + if (container) { + if (languageVersion < ScriptTarget.ES2015) { + if (container.kind === SyntaxKind.ArrowFunction) { + error(node, Diagnostics.The_arguments_object_cannot_be_referenced_in_an_arrow_function_in_ES5_Consider_using_a_standard_function_expression); + } + else if (hasSyntacticModifier(container, ModifierFlags.Async)) { + error(node, Diagnostics.The_arguments_object_cannot_be_referenced_in_an_async_function_or_method_in_ES5_Consider_using_a_standard_function_or_method); + } + } + + getNodeLinks(container).flags |= NodeCheckFlags.CaptureArguments; + while (container && isArrowFunction(container)) { + container = getContainingFunction(container); + if (container) { + getNodeLinks(container).flags |= NodeCheckFlags.CaptureArguments; + } + } + } + return; + } + + const localOrExportSymbol = getExportSymbolOfValueSymbolIfExported(symbol); + const targetSymbol = resolveAliasWithDeprecationCheck(localOrExportSymbol, node); + if (isDeprecatedSymbol(targetSymbol) && isUncalledFunctionReference(node, targetSymbol) && targetSymbol.declarations) { + addDeprecatedSuggestion(node, targetSymbol.declarations, node.escapedText as string); + } + + const declaration = localOrExportSymbol.valueDeclaration; + if (declaration && localOrExportSymbol.flags & SymbolFlags.Class) { + // When we downlevel classes we may emit some code outside of the class body. Due to the fact the + // class name is double-bound, we must ensure we mark references to the class name so that we can + // emit an alias to the class later. + if (isClassLike(declaration) && declaration.name !== node) { + let container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + while (container.kind !== SyntaxKind.SourceFile && container.parent !== declaration) { + container = getThisContainer(container, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + } + + if (container.kind !== SyntaxKind.SourceFile) { + getNodeLinks(declaration).flags |= NodeCheckFlags.ContainsConstructorReference; + getNodeLinks(container).flags |= NodeCheckFlags.ContainsConstructorReference; + getNodeLinks(node).flags |= NodeCheckFlags.ConstructorReference; + } + } + } + + checkNestedBlockScopedBinding(node, symbol); + } + + function checkIdentifier(node: Identifier, checkMode: CheckMode | undefined): Type { + if (isThisInTypeQuery(node)) { + return checkThisExpression(node); + } + + const symbol = getResolvedSymbol(node); + if (symbol === unknownSymbol) { + return errorType; + } + + checkIdentifierCalculateNodeCheckFlags(node, symbol); + + if (symbol === argumentsSymbol) { + if (isInPropertyInitializerOrClassStaticBlock(node)) { + return errorType; + } + return getTypeOfSymbol(symbol); + } + + if (shouldMarkIdentifierAliasReferenced(node)) { + markLinkedReferences(node, ReferenceHint.Identifier); + } + + const localOrExportSymbol = getExportSymbolOfValueSymbolIfExported(symbol); + let declaration = localOrExportSymbol.valueDeclaration; + + let type = getNarrowedTypeOfSymbol(localOrExportSymbol, node, checkMode); + const assignmentKind = getAssignmentTargetKind(node); + + if (assignmentKind) { + if ( + !(localOrExportSymbol.flags & SymbolFlags.Variable) && + !(isInJSFile(node) && localOrExportSymbol.flags & SymbolFlags.ValueModule) + ) { + const assignmentError = localOrExportSymbol.flags & SymbolFlags.Enum ? Diagnostics.Cannot_assign_to_0_because_it_is_an_enum + : localOrExportSymbol.flags & SymbolFlags.Class ? Diagnostics.Cannot_assign_to_0_because_it_is_a_class + : localOrExportSymbol.flags & SymbolFlags.Module ? Diagnostics.Cannot_assign_to_0_because_it_is_a_namespace + : localOrExportSymbol.flags & SymbolFlags.Function ? Diagnostics.Cannot_assign_to_0_because_it_is_a_function + : localOrExportSymbol.flags & SymbolFlags.Alias ? Diagnostics.Cannot_assign_to_0_because_it_is_an_import + : Diagnostics.Cannot_assign_to_0_because_it_is_not_a_variable; + + error(node, assignmentError, symbolToString(symbol)); + return errorType; + } + if (isReadonlySymbol(localOrExportSymbol)) { + if (localOrExportSymbol.flags & SymbolFlags.Variable) { + error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant, symbolToString(symbol)); + } + else { + error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(symbol)); + } + return errorType; + } + } + + const isAlias = localOrExportSymbol.flags & SymbolFlags.Alias; + + // We only narrow variables and parameters occurring in a non-assignment position. For all other + // entities we simply return the declared type. + if (localOrExportSymbol.flags & SymbolFlags.Variable) { + if (assignmentKind === AssignmentKind.Definite) { + return isInCompoundLikeAssignment(node) ? getBaseTypeOfLiteralType(type) : type; + } + } + else if (isAlias) { + declaration = getDeclarationOfAliasSymbol(symbol); + } + else { + return type; + } + + if (!declaration) { + return type; + } + + type = getNarrowableTypeForReference(type, node, checkMode); + + // The declaration container is the innermost function that encloses the declaration of the variable + // or parameter. The flow container is the innermost function starting with which we analyze the control + // flow graph to determine the control flow based type. + const isParameter = getRootDeclaration(declaration).kind === SyntaxKind.Parameter; + const declarationContainer = getControlFlowContainer(declaration); + let flowContainer = getControlFlowContainer(node); + const isOuterVariable = flowContainer !== declarationContainer; + const isSpreadDestructuringAssignmentTarget = node.parent && node.parent.parent && isSpreadAssignment(node.parent) && isDestructuringAssignmentTarget(node.parent.parent); + const isModuleExports = symbol.flags & SymbolFlags.ModuleExports; + const typeIsAutomatic = type === autoType || type === autoArrayType; + const isAutomaticTypeInNonNull = typeIsAutomatic && node.parent.kind === SyntaxKind.NonNullExpression; + // When the control flow originates in a function expression, arrow function, method, or accessor, and + // we are referencing a closed-over const variable or parameter or mutable local variable past its last + // assignment, we extend the origin of the control flow analysis to include the immediately enclosing + // control flow container. + while ( + flowContainer !== declarationContainer && ( + flowContainer.kind === SyntaxKind.FunctionExpression || + flowContainer.kind === SyntaxKind.ArrowFunction || + isObjectLiteralOrClassExpressionMethodOrAccessor(flowContainer) + ) && ( + isConstantVariable(localOrExportSymbol) && type !== autoArrayType || + isParameterOrMutableLocalVariable(localOrExportSymbol) && isPastLastAssignment(localOrExportSymbol, node) + ) + ) { + flowContainer = getControlFlowContainer(flowContainer); + } + // We only look for uninitialized variables in strict null checking mode, and only when we can analyze + // the entire control flow graph from the variable's declaration (i.e. when the flow container and + // declaration container are the same). + const assumeInitialized = isParameter || isAlias || isOuterVariable || isSpreadDestructuringAssignmentTarget || isModuleExports || isSameScopedBindingElement(node, declaration) || + type !== autoType && type !== autoArrayType && (!strictNullChecks || (type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void)) !== 0 || + isInTypeQuery(node) || isInAmbientOrTypeNode(node) || node.parent.kind === SyntaxKind.ExportSpecifier) || + node.parent.kind === SyntaxKind.NonNullExpression || + declaration.kind === SyntaxKind.VariableDeclaration && (declaration as VariableDeclaration).exclamationToken || + declaration.flags & NodeFlags.Ambient; + const initialType = isAutomaticTypeInNonNull ? undefinedType : + assumeInitialized ? (isParameter ? removeOptionalityFromDeclaredType(type, declaration as VariableLikeDeclaration) : type) : + typeIsAutomatic ? undefinedType : getOptionalType(type); + const flowType = isAutomaticTypeInNonNull ? getNonNullableType(getFlowTypeOfReference(node, type, initialType, flowContainer)) : + getFlowTypeOfReference(node, type, initialType, flowContainer); + // A variable is considered uninitialized when it is possible to analyze the entire control flow graph + // from declaration to use, and when the variable's declared type doesn't include undefined but the + // control flow based type does include undefined. + if (!isEvolvingArrayOperationTarget(node) && (type === autoType || type === autoArrayType)) { + if (flowType === autoType || flowType === autoArrayType) { + if (noImplicitAny) { + error(getNameOfDeclaration(declaration), Diagnostics.Variable_0_implicitly_has_type_1_in_some_locations_where_its_type_cannot_be_determined, symbolToString(symbol), typeToString(flowType)); + error(node, Diagnostics.Variable_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); + } + return convertAutoToAny(flowType); + } + } + else if (!assumeInitialized && !containsUndefinedType(type) && containsUndefinedType(flowType)) { + error(node, Diagnostics.Variable_0_is_used_before_being_assigned, symbolToString(symbol)); + // Return the declared type to reduce follow-on errors + return type; + } + return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType; + } + + function isSameScopedBindingElement(node: Identifier, declaration: Declaration) { + if (isBindingElement(declaration)) { + const bindingElement = findAncestor(node, isBindingElement); + return bindingElement && getRootDeclaration(bindingElement) === getRootDeclaration(declaration); + } + } + + function shouldMarkIdentifierAliasReferenced(node: Identifier): boolean { + const parent = node.parent; + if (parent) { + // A property access expression LHS? checkPropertyAccessExpression will handle that. + if (isPropertyAccessExpression(parent) && parent.expression === node) { + return false; + } + // Next two check for an identifier inside a type only export. + if (isExportSpecifier(parent) && parent.isTypeOnly) { + return false; + } + const greatGrandparent = parent.parent?.parent; + if (greatGrandparent && isExportDeclaration(greatGrandparent) && greatGrandparent.isTypeOnly) { + return false; + } + } + return true; + } + + function isInsideFunctionOrInstancePropertyInitializer(node: Node, threshold: Node): boolean { + return !!findAncestor(node, n => + n === threshold ? "quit" : isFunctionLike(n) || ( + n.parent && isPropertyDeclaration(n.parent) && !hasStaticModifier(n.parent) && n.parent.initializer === n + )); + } + + function getPartOfForStatementContainingNode(node: Node, container: ForStatement) { + return findAncestor(node, n => n === container ? "quit" : n === container.initializer || n === container.condition || n === container.incrementor || n === container.statement); + } + + function getEnclosingIterationStatement(node: Node): Node | undefined { + return findAncestor(node, n => (!n || nodeStartsNewLexicalEnvironment(n)) ? "quit" : isIterationStatement(n, /*lookInLabeledStatements*/ false)); + } + + function checkNestedBlockScopedBinding(node: Identifier, symbol: Symbol): void { + if ( + languageVersion >= ScriptTarget.ES2015 || + (symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.Class)) === 0 || + !symbol.valueDeclaration || + isSourceFile(symbol.valueDeclaration) || + symbol.valueDeclaration.parent.kind === SyntaxKind.CatchClause + ) { + return; + } + + // 1. walk from the use site up to the declaration and check + // if there is anything function like between declaration and use-site (is binding/class is captured in function). + // 2. walk from the declaration up to the boundary of lexical environment and check + // if there is an iteration statement in between declaration and boundary (is binding/class declared inside iteration statement) + + const container = getEnclosingBlockScopeContainer(symbol.valueDeclaration); + const isCaptured = isInsideFunctionOrInstancePropertyInitializer(node, container); + + const enclosingIterationStatement = getEnclosingIterationStatement(container); + if (enclosingIterationStatement) { + if (isCaptured) { + // mark iteration statement as containing block-scoped binding captured in some function + let capturesBlockScopeBindingInLoopBody = true; + if (isForStatement(container)) { + const varDeclList = getAncestor(symbol.valueDeclaration, SyntaxKind.VariableDeclarationList); + if (varDeclList && varDeclList.parent === container) { + const part = getPartOfForStatementContainingNode(node.parent, container); + if (part) { + const links = getNodeLinks(part); + links.flags |= NodeCheckFlags.ContainsCapturedBlockScopeBinding; + + const capturedBindings = links.capturedBlockScopeBindings || (links.capturedBlockScopeBindings = []); + pushIfUnique(capturedBindings, symbol); + + if (part === container.initializer) { + capturesBlockScopeBindingInLoopBody = false; // Initializer is outside of loop body + } + } + } + } + if (capturesBlockScopeBindingInLoopBody) { + getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; + } + } + + // mark variables that are declared in loop initializer and reassigned inside the body of ForStatement. + // if body of ForStatement will be converted to function then we'll need a extra machinery to propagate reassigned values back. + if (isForStatement(container)) { + const varDeclList = getAncestor(symbol.valueDeclaration, SyntaxKind.VariableDeclarationList); + if (varDeclList && varDeclList.parent === container && isAssignedInBodyOfForStatement(node, container)) { + getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.NeedsLoopOutParameter; + } + } + + // set 'declared inside loop' bit on the block-scoped binding + getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + } + + if (isCaptured) { + getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.CapturedBlockScopedBinding; + } + } + + function isBindingCapturedByNode(node: Node, decl: VariableDeclaration | BindingElement) { + const links = getNodeLinks(node); + return !!links && contains(links.capturedBlockScopeBindings, getSymbolOfDeclaration(decl)); + } + + function isAssignedInBodyOfForStatement(node: Identifier, container: ForStatement): boolean { + // skip parenthesized nodes + let current: Node = node; + while (current.parent.kind === SyntaxKind.ParenthesizedExpression) { + current = current.parent; + } + + // check if node is used as LHS in some assignment expression + let isAssigned = false; + if (isAssignmentTarget(current)) { + isAssigned = true; + } + else if ((current.parent.kind === SyntaxKind.PrefixUnaryExpression || current.parent.kind === SyntaxKind.PostfixUnaryExpression)) { + const expr = current.parent as PrefixUnaryExpression | PostfixUnaryExpression; + isAssigned = expr.operator === SyntaxKind.PlusPlusToken || expr.operator === SyntaxKind.MinusMinusToken; + } + + if (!isAssigned) { + return false; + } + + // at this point we know that node is the target of assignment + // now check that modification happens inside the statement part of the ForStatement + return !!findAncestor(current, n => n === container ? "quit" : n === container.statement); + } + + function captureLexicalThis(node: Node, container: Node): void { + getNodeLinks(node).flags |= NodeCheckFlags.LexicalThis; + if (container.kind === SyntaxKind.PropertyDeclaration || container.kind === SyntaxKind.Constructor) { + const classNode = container.parent; + getNodeLinks(classNode).flags |= NodeCheckFlags.CaptureThis; + } + else { + getNodeLinks(container).flags |= NodeCheckFlags.CaptureThis; + } + } + + function findFirstSuperCall(node: Node): SuperCall | undefined { + return isSuperCall(node) ? node : + isFunctionLike(node) ? undefined : + forEachChild(node, findFirstSuperCall); + } + + /** + * Check if the given class-declaration extends null then return true. + * Otherwise, return false + * @param classDecl a class declaration to check if it extends null + */ + function classDeclarationExtendsNull(classDecl: ClassLikeDeclaration): boolean { + const classSymbol = getSymbolOfDeclaration(classDecl); + const classInstanceType = getDeclaredTypeOfSymbol(classSymbol) as InterfaceType; + const baseConstructorType = getBaseConstructorTypeOfClass(classInstanceType); + + return baseConstructorType === nullWideningType; + } + + function checkThisBeforeSuper(node: Node, container: Node, diagnosticMessage: DiagnosticMessage) { + const containingClassDecl = container.parent as ClassDeclaration; + const baseTypeNode = getClassExtendsHeritageElement(containingClassDecl); + + // If a containing class does not have extends clause or the class extends null + // skip checking whether super statement is called before "this" accessing. + if (baseTypeNode && !classDeclarationExtendsNull(containingClassDecl)) { + if (canHaveFlowNode(node) && node.flowNode && !isPostSuperFlowNode(node.flowNode, /*noCacheCheck*/ false)) { + error(node, diagnosticMessage); + } + } + } + + function checkThisInStaticClassFieldInitializerInDecoratedClass(thisExpression: Node, container: Node) { + if ( + isPropertyDeclaration(container) && hasStaticModifier(container) && legacyDecorators && + container.initializer && textRangeContainsPositionInclusive(container.initializer, thisExpression.pos) && hasDecorators(container.parent) + ) { + error(thisExpression, Diagnostics.Cannot_use_this_in_a_static_property_initializer_of_a_decorated_class); + } + } + + function checkThisExpression(node: Node): Type { + const isNodeInTypeQuery = isInTypeQuery(node); + // Stop at the first arrow function so that we can + // tell whether 'this' needs to be captured. + let container = getThisContainer(node, /*includeArrowFunctions*/ true, /*includeClassComputedPropertyName*/ true); + let capturedByArrowFunction = false; + let thisInComputedPropertyName = false; + + if (container.kind === SyntaxKind.Constructor) { + checkThisBeforeSuper(node, container, Diagnostics.super_must_be_called_before_accessing_this_in_the_constructor_of_a_derived_class); + } + + while (true) { + // Now skip arrow functions to get the "real" owner of 'this'. + if (container.kind === SyntaxKind.ArrowFunction) { + container = getThisContainer(container, /*includeArrowFunctions*/ false, !thisInComputedPropertyName); + capturedByArrowFunction = true; + } + + if (container.kind === SyntaxKind.ComputedPropertyName) { + container = getThisContainer(container, !capturedByArrowFunction, /*includeClassComputedPropertyName*/ false); + thisInComputedPropertyName = true; + continue; + } + + break; + } + + checkThisInStaticClassFieldInitializerInDecoratedClass(node, container); + if (thisInComputedPropertyName) { + error(node, Diagnostics.this_cannot_be_referenced_in_a_computed_property_name); + } + else { + switch (container.kind) { + case SyntaxKind.ModuleDeclaration: + error(node, Diagnostics.this_cannot_be_referenced_in_a_module_or_namespace_body); + // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks + break; + case SyntaxKind.EnumDeclaration: + error(node, Diagnostics.this_cannot_be_referenced_in_current_location); + // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks + break; + } + } + + // When targeting es6, mark that we'll need to capture `this` in its lexically bound scope. + if (!isNodeInTypeQuery && capturedByArrowFunction && languageVersion < ScriptTarget.ES2015) { + captureLexicalThis(node, container); + } + + const type = tryGetThisTypeAt(node, /*includeGlobalThis*/ true, container); + if (noImplicitThis) { + const globalThisType = getTypeOfSymbol(globalThisSymbol); + if (type === globalThisType && capturedByArrowFunction) { + error(node, Diagnostics.The_containing_arrow_function_captures_the_global_value_of_this); + } + else if (!type) { + // With noImplicitThis, functions may not reference 'this' if it has type 'any' + const diag = error(node, Diagnostics.this_implicitly_has_type_any_because_it_does_not_have_a_type_annotation); + if (!isSourceFile(container)) { + const outsideThis = tryGetThisTypeAt(container); + if (outsideThis && outsideThis !== globalThisType) { + addRelatedInfo(diag, createDiagnosticForNode(container, Diagnostics.An_outer_value_of_this_is_shadowed_by_this_container)); + } + } + } + } + return type || anyType; + } + + function tryGetThisTypeAt(node: Node, includeGlobalThis = true, container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)): Type | undefined { + const isInJS = isInJSFile(node); + if ( + isFunctionLike(container) && + (!isInParameterInitializerBeforeContainingFunction(node) || getThisParameter(container)) + ) { + let thisType = getThisTypeOfDeclaration(container) || isInJS && getTypeForThisExpressionFromJSDoc(container); + // Note: a parameter initializer should refer to class-this unless function-this is explicitly annotated. + // If this is a function in a JS file, it might be a class method. + if (!thisType) { + const className = getClassNameFromPrototypeMethod(container); + if (isInJS && className) { + const classSymbol = checkExpression(className).symbol; + if (classSymbol && classSymbol.members && (classSymbol.flags & SymbolFlags.Function)) { + thisType = (getDeclaredTypeOfSymbol(classSymbol) as InterfaceType).thisType; + } + } + else if (isJSConstructor(container)) { + thisType = (getDeclaredTypeOfSymbol(getMergedSymbol(container.symbol)) as InterfaceType).thisType; + } + thisType ||= getContextualThisParameterType(container); + } + + if (thisType) { + return getFlowTypeOfReference(node, thisType); + } + } + + if (isClassLike(container.parent)) { + const symbol = getSymbolOfDeclaration(container.parent); + const type = isStatic(container) ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!; + return getFlowTypeOfReference(node, type); + } + + if (isSourceFile(container)) { + // look up in the source file's locals or exports + if (container.commonJsModuleIndicator) { + const fileSymbol = getSymbolOfDeclaration(container); + return fileSymbol && getTypeOfSymbol(fileSymbol); + } + else if (container.externalModuleIndicator) { + // TODO: Maybe issue a better error than 'object is possibly undefined' + return undefinedType; + } + else if (includeGlobalThis) { + return getTypeOfSymbol(globalThisSymbol); + } + } + } + + function getExplicitThisType(node: Expression) { + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (isFunctionLike(container)) { + const signature = getSignatureFromDeclaration(container); + if (signature.thisParameter) { + return getExplicitTypeOfSymbol(signature.thisParameter); + } + } + if (isClassLike(container.parent)) { + const symbol = getSymbolOfDeclaration(container.parent); + return isStatic(container) ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!; + } + } + + function getClassNameFromPrototypeMethod(container: Node) { + // Check if it's the RHS of a x.prototype.y = function [name]() { .... } + if ( + container.kind === SyntaxKind.FunctionExpression && + isBinaryExpression(container.parent) && + getAssignmentDeclarationKind(container.parent) === AssignmentDeclarationKind.PrototypeProperty + ) { + // Get the 'x' of 'x.prototype.y = container' + return ((container.parent // x.prototype.y = container + .left as PropertyAccessExpression) // x.prototype.y + .expression as PropertyAccessExpression) // x.prototype + .expression; // x + } + // x.prototype = { method() { } } + else if ( + container.kind === SyntaxKind.MethodDeclaration && + container.parent.kind === SyntaxKind.ObjectLiteralExpression && + isBinaryExpression(container.parent.parent) && + getAssignmentDeclarationKind(container.parent.parent) === AssignmentDeclarationKind.Prototype + ) { + return (container.parent.parent.left as PropertyAccessExpression).expression; + } + // x.prototype = { method: function() { } } + else if ( + container.kind === SyntaxKind.FunctionExpression && + container.parent.kind === SyntaxKind.PropertyAssignment && + container.parent.parent.kind === SyntaxKind.ObjectLiteralExpression && + isBinaryExpression(container.parent.parent.parent) && + getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.Prototype + ) { + return (container.parent.parent.parent.left as PropertyAccessExpression).expression; + } + // Object.defineProperty(x, "method", { value: function() { } }); + // Object.defineProperty(x, "method", { set: (x: () => void) => void }); + // Object.defineProperty(x, "method", { get: () => function() { }) }); + else if ( + container.kind === SyntaxKind.FunctionExpression && + isPropertyAssignment(container.parent) && + isIdentifier(container.parent.name) && + (container.parent.name.escapedText === "value" || container.parent.name.escapedText === "get" || container.parent.name.escapedText === "set") && + isObjectLiteralExpression(container.parent.parent) && + isCallExpression(container.parent.parent.parent) && + container.parent.parent.parent.arguments[2] === container.parent.parent && + getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty + ) { + return (container.parent.parent.parent.arguments[0] as PropertyAccessExpression).expression; + } + // Object.defineProperty(x, "method", { value() { } }); + // Object.defineProperty(x, "method", { set(x: () => void) {} }); + // Object.defineProperty(x, "method", { get() { return () => {} } }); + else if ( + isMethodDeclaration(container) && + isIdentifier(container.name) && + (container.name.escapedText === "value" || container.name.escapedText === "get" || container.name.escapedText === "set") && + isObjectLiteralExpression(container.parent) && + isCallExpression(container.parent.parent) && + container.parent.parent.arguments[2] === container.parent && + getAssignmentDeclarationKind(container.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty + ) { + return (container.parent.parent.arguments[0] as PropertyAccessExpression).expression; + } + } + + function getTypeForThisExpressionFromJSDoc(node: SignatureDeclaration) { + const thisTag = getJSDocThisTag(node); + if (thisTag && thisTag.typeExpression) { + return getTypeFromTypeNode(thisTag.typeExpression); + } + const signature = getSignatureOfTypeTag(node); + if (signature) { + return getThisTypeOfSignature(signature); + } + } + + function isInConstructorArgumentInitializer(node: Node, constructorDecl: Node): boolean { + return !!findAncestor(node, n => isFunctionLikeDeclaration(n) ? "quit" : n.kind === SyntaxKind.Parameter && n.parent === constructorDecl); + } + + function checkSuperExpression(node: Node): Type { + const isCallExpression = node.parent.kind === SyntaxKind.CallExpression && (node.parent as CallExpression).expression === node; + + const immediateContainer = getSuperContainer(node, /*stopOnFunctions*/ true); + let container = immediateContainer; + let needToCaptureLexicalThis = false; + let inAsyncFunction = false; + + // adjust the container reference in case if super is used inside arrow functions with arbitrarily deep nesting + if (!isCallExpression) { + while (container && container.kind === SyntaxKind.ArrowFunction) { + if (hasSyntacticModifier(container, ModifierFlags.Async)) inAsyncFunction = true; + container = getSuperContainer(container, /*stopOnFunctions*/ true); + needToCaptureLexicalThis = languageVersion < ScriptTarget.ES2015; + } + if (container && hasSyntacticModifier(container, ModifierFlags.Async)) inAsyncFunction = true; + } + + let nodeCheckFlag: NodeCheckFlags = 0; + + if (!container || !isLegalUsageOfSuperExpression(container)) { + // issue more specific error if super is used in computed property name + // class A { foo() { return "1" }} + // class B { + // [super.foo()]() {} + // } + const current = findAncestor(node, n => n === container ? "quit" : n.kind === SyntaxKind.ComputedPropertyName); + if (current && current.kind === SyntaxKind.ComputedPropertyName) { + error(node, Diagnostics.super_cannot_be_referenced_in_a_computed_property_name); + } + else if (isCallExpression) { + error(node, Diagnostics.Super_calls_are_not_permitted_outside_constructors_or_in_nested_functions_inside_constructors); + } + else if (!container || !container.parent || !(isClassLike(container.parent) || container.parent.kind === SyntaxKind.ObjectLiteralExpression)) { + error(node, Diagnostics.super_can_only_be_referenced_in_members_of_derived_classes_or_object_literal_expressions); + } + else { + error(node, Diagnostics.super_property_access_is_permitted_only_in_a_constructor_member_function_or_member_accessor_of_a_derived_class); + } + return errorType; + } + + if (!isCallExpression && immediateContainer!.kind === SyntaxKind.Constructor) { + checkThisBeforeSuper(node, container, Diagnostics.super_must_be_called_before_accessing_a_property_of_super_in_the_constructor_of_a_derived_class); + } + + if (isStatic(container) || isCallExpression) { + nodeCheckFlag = NodeCheckFlags.SuperStatic; + if ( + !isCallExpression && + languageVersion >= ScriptTarget.ES2015 && languageVersion <= ScriptTarget.ES2021 && + (isPropertyDeclaration(container) || isClassStaticBlockDeclaration(container)) + ) { + // for `super.x` or `super[x]` in a static initializer, mark all enclosing + // block scope containers so that we can report potential collisions with + // `Reflect`. + forEachEnclosingBlockScopeContainer(node.parent, current => { + if (!isSourceFile(current) || isExternalOrCommonJsModule(current)) { + getNodeLinks(current).flags |= NodeCheckFlags.ContainsSuperPropertyInStaticInitializer; + } + }); + } + } + else { + nodeCheckFlag = NodeCheckFlags.SuperInstance; + } + + getNodeLinks(node).flags |= nodeCheckFlag; + + // Due to how we emit async functions, we need to specialize the emit for an async method that contains a `super` reference. + // This is due to the fact that we emit the body of an async function inside of a generator function. As generator + // functions cannot reference `super`, we emit a helper inside of the method body, but outside of the generator. This helper + // uses an arrow function, which is permitted to reference `super`. + // + // There are two primary ways we can access `super` from within an async method. The first is getting the value of a property + // or indexed access on super, either as part of a right-hand-side expression or call expression. The second is when setting the value + // of a property or indexed access, either as part of an assignment expression or destructuring assignment. + // + // The simplest case is reading a value, in which case we will emit something like the following: + // + // // ts + // ... + // async asyncMethod() { + // let x = await super.asyncMethod(); + // return x; + // } + // ... + // + // // js + // ... + // asyncMethod() { + // const _super = Object.create(null, { + // asyncMethod: { get: () => super.asyncMethod }, + // }); + // return __awaiter(this, arguments, Promise, function *() { + // let x = yield _super.asyncMethod.call(this); + // return x; + // }); + // } + // ... + // + // The more complex case is when we wish to assign a value, especially as part of a destructuring assignment. As both cases + // are legal in ES6, but also likely less frequent, we only emit setters if there is an assignment: + // + // // ts + // ... + // async asyncMethod(ar: Promise) { + // [super.a, super.b] = await ar; + // } + // ... + // + // // js + // ... + // asyncMethod(ar) { + // const _super = Object.create(null, { + // a: { get: () => super.a, set: (v) => super.a = v }, + // b: { get: () => super.b, set: (v) => super.b = v } + // }; + // return __awaiter(this, arguments, Promise, function *() { + // [_super.a, _super.b] = yield ar; + // }); + // } + // ... + // + // Creating an object that has getter and setters instead of just an accessor function is required for destructuring assignments + // as a call expression cannot be used as the target of a destructuring assignment while a property access can. + // + // For element access expressions (`super[x]`), we emit a generic helper that forwards the element access in both situations. + if (container.kind === SyntaxKind.MethodDeclaration && inAsyncFunction) { + if (isSuperProperty(node.parent) && isAssignmentTarget(node.parent)) { + getNodeLinks(container).flags |= NodeCheckFlags.MethodWithSuperPropertyAssignmentInAsync; + } + else { + getNodeLinks(container).flags |= NodeCheckFlags.MethodWithSuperPropertyAccessInAsync; + } + } + + if (needToCaptureLexicalThis) { + // call expressions are allowed only in constructors so they should always capture correct 'this' + // super property access expressions can also appear in arrow functions - + // in this case they should also use correct lexical this + captureLexicalThis(node.parent, container); + } + + if (container.parent.kind === SyntaxKind.ObjectLiteralExpression) { + if (languageVersion < ScriptTarget.ES2015) { + error(node, Diagnostics.super_is_only_allowed_in_members_of_object_literal_expressions_when_option_target_is_ES2015_or_higher); + return errorType; + } + else { + // for object literal assume that type of 'super' is 'any' + return anyType; + } + } + + // at this point the only legal case for parent is ClassLikeDeclaration + const classLikeDeclaration = container.parent as ClassLikeDeclaration; + if (!getClassExtendsHeritageElement(classLikeDeclaration)) { + error(node, Diagnostics.super_can_only_be_referenced_in_a_derived_class); + return errorType; + } + + if (classDeclarationExtendsNull(classLikeDeclaration)) { + return isCallExpression ? errorType : nullWideningType; + } + + const classType = getDeclaredTypeOfSymbol(getSymbolOfDeclaration(classLikeDeclaration)) as InterfaceType; + const baseClassType = classType && getBaseTypes(classType)[0]; + if (!baseClassType) { + return errorType; + } + + if (container.kind === SyntaxKind.Constructor && isInConstructorArgumentInitializer(node, container)) { + // issue custom error message for super property access in constructor arguments (to be aligned with old compiler) + error(node, Diagnostics.super_cannot_be_referenced_in_constructor_arguments); + return errorType; + } + + return nodeCheckFlag === NodeCheckFlags.SuperStatic + ? getBaseConstructorTypeOfClass(classType) + : getTypeWithThisArgument(baseClassType, classType.thisType); + + function isLegalUsageOfSuperExpression(container: Node): boolean { + if (isCallExpression) { + // TS 1.0 SPEC (April 2014): 4.8.1 + // Super calls are only permitted in constructors of derived classes + return container.kind === SyntaxKind.Constructor; + } + else { + // TS 1.0 SPEC (April 2014) + // 'super' property access is allowed + // - In a constructor, instance member function, instance member accessor, or instance member variable initializer where this references a derived class instance + // - In a static member function or static member accessor + + // topmost container must be something that is directly nested in the class declaration\object literal expression + if (isClassLike(container.parent) || container.parent.kind === SyntaxKind.ObjectLiteralExpression) { + if (isStatic(container)) { + return container.kind === SyntaxKind.MethodDeclaration || + container.kind === SyntaxKind.MethodSignature || + container.kind === SyntaxKind.GetAccessor || + container.kind === SyntaxKind.SetAccessor || + container.kind === SyntaxKind.PropertyDeclaration || + container.kind === SyntaxKind.ClassStaticBlockDeclaration; + } + else { + return container.kind === SyntaxKind.MethodDeclaration || + container.kind === SyntaxKind.MethodSignature || + container.kind === SyntaxKind.GetAccessor || + container.kind === SyntaxKind.SetAccessor || + container.kind === SyntaxKind.PropertyDeclaration || + container.kind === SyntaxKind.PropertySignature || + container.kind === SyntaxKind.Constructor; + } + } + } + + return false; + } + } + + function getContainingObjectLiteral(func: SignatureDeclaration): ObjectLiteralExpression | undefined { + return (func.kind === SyntaxKind.MethodDeclaration || + func.kind === SyntaxKind.GetAccessor || + func.kind === SyntaxKind.SetAccessor) && func.parent.kind === SyntaxKind.ObjectLiteralExpression ? func.parent : + func.kind === SyntaxKind.FunctionExpression && func.parent.kind === SyntaxKind.PropertyAssignment ? func.parent.parent as ObjectLiteralExpression : + undefined; + } + + function getThisTypeArgument(type: Type): Type | undefined { + return getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).target === globalThisType ? getTypeArguments(type as TypeReference)[0] : undefined; + } + + function getThisTypeFromContextualType(type: Type): Type | undefined { + return mapType(type, t => { + return t.flags & TypeFlags.Intersection ? forEach((t as IntersectionType).types, getThisTypeArgument) : getThisTypeArgument(t); + }); + } + + function getThisTypeOfObjectLiteralFromContextualType(containingLiteral: ObjectLiteralExpression, contextualType: Type | undefined) { + let literal = containingLiteral; + let type = contextualType; + while (type) { + const thisType = getThisTypeFromContextualType(type); + if (thisType) { + return thisType; + } + if (literal.parent.kind !== SyntaxKind.PropertyAssignment) { + break; + } + literal = literal.parent.parent as ObjectLiteralExpression; + type = getApparentTypeOfContextualType(literal, /*contextFlags*/ undefined); + } + } + + function getContextualThisParameterType(func: SignatureDeclaration): Type | undefined { + if (func.kind === SyntaxKind.ArrowFunction) { + return undefined; + } + if (isContextSensitiveFunctionOrObjectLiteralMethod(func)) { + const contextualSignature = getContextualSignature(func); + if (contextualSignature) { + const thisParameter = contextualSignature.thisParameter; + if (thisParameter) { + return getTypeOfSymbol(thisParameter); + } + } + } + const inJs = isInJSFile(func); + if (noImplicitThis || inJs) { + const containingLiteral = getContainingObjectLiteral(func); + if (containingLiteral) { + // We have an object literal method. Check if the containing object literal has a contextual type + // that includes a ThisType. If so, T is the contextual type for 'this'. We continue looking in + // any directly enclosing object literals. + const contextualType = getApparentTypeOfContextualType(containingLiteral, /*contextFlags*/ undefined); + const thisType = getThisTypeOfObjectLiteralFromContextualType(containingLiteral, contextualType); + if (thisType) { + return instantiateType(thisType, getMapperFromContext(getInferenceContext(containingLiteral))); + } + // There was no contextual ThisType for the containing object literal, so the contextual type + // for 'this' is the non-null form of the contextual type for the containing object literal or + // the type of the object literal itself. + return getWidenedType(contextualType ? getNonNullableType(contextualType) : checkExpressionCached(containingLiteral)); + } + // In an assignment of the form 'obj.xxx = function(...)' or 'obj[xxx] = function(...)', the + // contextual type for 'this' is 'obj'. + const parent = walkUpParenthesizedExpressions(func.parent); + if (isAssignmentExpression(parent)) { + const target = parent.left; + if (isAccessExpression(target)) { + const { expression } = target; + // Don't contextually type `this` as `exports` in `exports.Point = function(x, y) { this.x = x; this.y = y; }` + if (inJs && isIdentifier(expression)) { + const sourceFile = getSourceFileOfNode(parent); + if (sourceFile.commonJsModuleIndicator && getResolvedSymbol(expression) === sourceFile.symbol) { + return undefined; + } + } + + return getWidenedType(checkExpressionCached(expression)); + } + } + } + return undefined; + } + + // Return contextual type of parameter or undefined if no contextual type is available + function getContextuallyTypedParameterType(parameter: ParameterDeclaration): Type | undefined { + const func = parameter.parent; + if (!isContextSensitiveFunctionOrObjectLiteralMethod(func)) { + return undefined; + } + const iife = getImmediatelyInvokedFunctionExpression(func); + if (iife && iife.arguments) { + const args = getEffectiveCallArguments(iife); + const indexOfParameter = func.parameters.indexOf(parameter); + if (parameter.dotDotDotToken) { + return getSpreadArgumentType(args, indexOfParameter, args.length, anyType, /*context*/ undefined, CheckMode.Normal); + } + const links = getNodeLinks(iife); + const cached = links.resolvedSignature; + links.resolvedSignature = anySignature; + const type = indexOfParameter < args.length ? + getWidenedLiteralType(checkExpression(args[indexOfParameter])) : + parameter.initializer ? undefined : undefinedWideningType; + links.resolvedSignature = cached; + return type; + } + const contextualSignature = getContextualSignature(func); + if (contextualSignature) { + const index = func.parameters.indexOf(parameter) - (getThisParameter(func) ? 1 : 0); + return parameter.dotDotDotToken && lastOrUndefined(func.parameters) === parameter ? + getRestTypeAtPosition(contextualSignature, index) : + tryGetTypeAtPosition(contextualSignature, index); + } + } + + function getContextualTypeForVariableLikeDeclaration(declaration: VariableLikeDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + const typeNode = getEffectiveTypeAnnotationNode(declaration) || (isInJSFile(declaration) ? tryGetJSDocSatisfiesTypeNode(declaration) : undefined); + if (typeNode) { + return getTypeFromTypeNode(typeNode); + } + switch (declaration.kind) { + case SyntaxKind.Parameter: + return getContextuallyTypedParameterType(declaration); + case SyntaxKind.BindingElement: + return getContextualTypeForBindingElement(declaration, contextFlags); + case SyntaxKind.PropertyDeclaration: + if (isStatic(declaration)) { + return getContextualTypeForStaticPropertyDeclaration(declaration, contextFlags); + } + // By default, do nothing and return undefined - only the above cases have context implied by a parent + } + } + + function getContextualTypeForBindingElement(declaration: BindingElement, contextFlags: ContextFlags | undefined): Type | undefined { + const parent = declaration.parent.parent; + const name = declaration.propertyName || declaration.name; + const parentType = getContextualTypeForVariableLikeDeclaration(parent, contextFlags) || + parent.kind !== SyntaxKind.BindingElement && parent.initializer && checkDeclarationInitializer(parent, declaration.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal); + if (!parentType || isBindingPattern(name) || isComputedNonLiteralName(name)) return undefined; + if (parent.name.kind === SyntaxKind.ArrayBindingPattern) { + const index = indexOfNode(declaration.parent.elements, declaration); + if (index < 0) return undefined; + return getContextualTypeForElementExpression(parentType, index); + } + const nameType = getLiteralTypeFromPropertyName(name); + if (isTypeUsableAsPropertyName(nameType)) { + const text = getPropertyNameFromType(nameType); + return getTypeOfPropertyOfType(parentType, text); + } + } + + function getContextualTypeForStaticPropertyDeclaration(declaration: PropertyDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + const parentType = isExpression(declaration.parent) && getContextualType(declaration.parent, contextFlags); + if (!parentType) return undefined; + return getTypeOfPropertyOfContextualType(parentType, getSymbolOfDeclaration(declaration).escapedName); + } + + // In a variable, parameter or property declaration with a type annotation, + // the contextual type of an initializer expression is the type of the variable, parameter or property. + // Otherwise, in a parameter declaration of a contextually typed function expression, + // the contextual type of an initializer expression is the contextual type of the parameter. + // Otherwise, in a variable or parameter declaration with a binding pattern name, + // the contextual type of an initializer expression is the type implied by the binding pattern. + // Otherwise, in a binding pattern inside a variable or parameter declaration, + // the contextual type of an initializer expression is the type annotation of the containing declaration, if present. + function getContextualTypeForInitializerExpression(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const declaration = node.parent as VariableLikeDeclaration; + if (hasInitializer(declaration) && node === declaration.initializer) { + const result = getContextualTypeForVariableLikeDeclaration(declaration, contextFlags); + if (result) { + return result; + } + if (!(contextFlags! & ContextFlags.SkipBindingPatterns) && isBindingPattern(declaration.name) && declaration.name.elements.length > 0) { + return getTypeFromBindingPattern(declaration.name, /*includePatternInType*/ true, /*reportErrors*/ false); + } + } + return undefined; + } + + function getContextualTypeForReturnExpression(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const func = getContainingFunction(node); + if (func) { + let contextualReturnType = getContextualReturnType(func, contextFlags); + if (contextualReturnType) { + const functionFlags = getFunctionFlags(func); + if (functionFlags & FunctionFlags.Generator) { // Generator or AsyncGenerator function + const isAsyncGenerator = (functionFlags & FunctionFlags.Async) !== 0; + if (contextualReturnType.flags & TypeFlags.Union) { + contextualReturnType = filterType(contextualReturnType, type => !!getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, type, isAsyncGenerator)); + } + const iterationReturnType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, contextualReturnType, (functionFlags & FunctionFlags.Async) !== 0); + if (!iterationReturnType) { + return undefined; + } + contextualReturnType = iterationReturnType; + // falls through to unwrap Promise for AsyncGenerators + } + + if (functionFlags & FunctionFlags.Async) { // Async function or AsyncGenerator function + // Get the awaited type without the `Awaited` alias + const contextualAwaitedType = mapType(contextualReturnType, getAwaitedTypeNoAlias); + return contextualAwaitedType && getUnionType([contextualAwaitedType, createPromiseLikeType(contextualAwaitedType)]); + } + + return contextualReturnType; // Regular function or Generator function + } + } + return undefined; + } + + function getContextualTypeForAwaitOperand(node: AwaitExpression, contextFlags: ContextFlags | undefined): Type | undefined { + const contextualType = getContextualType(node, contextFlags); + if (contextualType) { + const contextualAwaitedType = getAwaitedTypeNoAlias(contextualType); + return contextualAwaitedType && getUnionType([contextualAwaitedType, createPromiseLikeType(contextualAwaitedType)]); + } + return undefined; + } + + function getContextualTypeForYieldOperand(node: YieldExpression, contextFlags: ContextFlags | undefined): Type | undefined { + const func = getContainingFunction(node); + if (func) { + const functionFlags = getFunctionFlags(func); + let contextualReturnType = getContextualReturnType(func, contextFlags); + if (contextualReturnType) { + const isAsyncGenerator = (functionFlags & FunctionFlags.Async) !== 0; + if (!node.asteriskToken && contextualReturnType.flags & TypeFlags.Union) { + contextualReturnType = filterType(contextualReturnType, type => !!getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, type, isAsyncGenerator)); + } + if (node.asteriskToken) { + const iterationTypes = getIterationTypesOfGeneratorFunctionReturnType(contextualReturnType, isAsyncGenerator); + const yieldType = iterationTypes?.yieldType ?? silentNeverType; + const returnType = getContextualType(node, contextFlags) ?? silentNeverType; + const nextType = iterationTypes?.nextType ?? unknownType; + const generatorType = createGeneratorType(yieldType, returnType, nextType, /*isAsyncGenerator*/ false); + if (isAsyncGenerator) { + const asyncGeneratorType = createGeneratorType(yieldType, returnType, nextType, /*isAsyncGenerator*/ true); + return getUnionType([generatorType, asyncGeneratorType]); + } + return generatorType; + } + return getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Yield, contextualReturnType, isAsyncGenerator); + } + } + + return undefined; + } + + function isInParameterInitializerBeforeContainingFunction(node: Node) { + let inBindingInitializer = false; + while (node.parent && !isFunctionLike(node.parent)) { + if (isParameter(node.parent) && (inBindingInitializer || node.parent.initializer === node)) { + return true; + } + if (isBindingElement(node.parent) && node.parent.initializer === node) { + inBindingInitializer = true; + } + + node = node.parent; + } + + return false; + } + + function getContextualIterationType(kind: IterationTypeKind, functionDecl: SignatureDeclaration): Type | undefined { + const isAsync = !!(getFunctionFlags(functionDecl) & FunctionFlags.Async); + const contextualReturnType = getContextualReturnType(functionDecl, /*contextFlags*/ undefined); + if (contextualReturnType) { + return getIterationTypeOfGeneratorFunctionReturnType(kind, contextualReturnType, isAsync) + || undefined; + } + + return undefined; + } + + function getContextualReturnType(functionDecl: SignatureDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + // If the containing function has a return type annotation, is a constructor, or is a get accessor whose + // corresponding set accessor has a type annotation, return statements in the function are contextually typed + const returnType = getReturnTypeFromAnnotation(functionDecl); + if (returnType) { + return returnType; + } + // Otherwise, if the containing function is contextually typed by a function type with exactly one call signature + // and that call signature is non-generic, return statements are contextually typed by the return type of the signature + const signature = getContextualSignatureForFunctionLikeDeclaration(functionDecl as FunctionExpression); + if (signature && !isResolvingReturnTypeOfSignature(signature)) { + const returnType = getReturnTypeOfSignature(signature); + const functionFlags = getFunctionFlags(functionDecl); + if (functionFlags & FunctionFlags.Generator) { + return filterType(returnType, t => { + return !!(t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.InstantiableNonPrimitive)) || checkGeneratorInstantiationAssignabilityToReturnType(t, functionFlags, /*errorNode*/ undefined); + }); + } + if (functionFlags & FunctionFlags.Async) { + return filterType(returnType, t => { + return !!(t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.InstantiableNonPrimitive)) || !!getAwaitedTypeOfPromise(t); + }); + } + return returnType; + } + const iife = getImmediatelyInvokedFunctionExpression(functionDecl); + if (iife) { + return getContextualType(iife, contextFlags); + } + return undefined; + } + + // In a typed function call, an argument or substitution expression is contextually typed by the type of the corresponding parameter. + function getContextualTypeForArgument(callTarget: CallLikeExpression, arg: Expression): Type | undefined { + const args = getEffectiveCallArguments(callTarget); + const argIndex = args.indexOf(arg); // -1 for e.g. the expression of a CallExpression, or the tag of a TaggedTemplateExpression + return argIndex === -1 ? undefined : getContextualTypeForArgumentAtIndex(callTarget, argIndex); + } + + function getContextualTypeForArgumentAtIndex(callTarget: CallLikeExpression, argIndex: number): Type { + if (isImportCall(callTarget)) { + return argIndex === 0 ? stringType : + argIndex === 1 ? getGlobalImportCallOptionsType(/*reportErrors*/ false) : + anyType; + } + + // If we're already in the process of resolving the given signature, don't resolve again as + // that could cause infinite recursion. Instead, return anySignature. + const signature = getNodeLinks(callTarget).resolvedSignature === resolvingSignature ? resolvingSignature : getResolvedSignature(callTarget); + + if (isJsxOpeningLikeElement(callTarget) && argIndex === 0) { + return getEffectiveFirstArgumentForJsxSignature(signature, callTarget); + } + const restIndex = signature.parameters.length - 1; + return signatureHasRestParameter(signature) && argIndex >= restIndex ? + getIndexedAccessType(getTypeOfSymbol(signature.parameters[restIndex]), getNumberLiteralType(argIndex - restIndex), AccessFlags.Contextual) : + getTypeAtPosition(signature, argIndex); + } + + function getContextualTypeForDecorator(decorator: Decorator): Type | undefined { + const signature = getDecoratorCallSignature(decorator); + return signature ? getOrCreateTypeFromSignature(signature) : undefined; + } + + function getContextualTypeForSubstitutionExpression(template: TemplateExpression, substitutionExpression: Expression) { + if (template.parent.kind === SyntaxKind.TaggedTemplateExpression) { + return getContextualTypeForArgument(template.parent as TaggedTemplateExpression, substitutionExpression); + } + + return undefined; + } + + function getContextualTypeForBinaryOperand(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const binaryExpression = node.parent as BinaryExpression; + const { left, operatorToken, right } = binaryExpression; + switch (operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: + case SyntaxKind.BarBarEqualsToken: + case SyntaxKind.QuestionQuestionEqualsToken: + return node === right ? getContextualTypeForAssignmentDeclaration(binaryExpression) : undefined; + case SyntaxKind.BarBarToken: + case SyntaxKind.QuestionQuestionToken: + // When an || expression has a contextual type, the operands are contextually typed by that type, except + // when that type originates in a binding pattern, the right operand is contextually typed by the type of + // the left operand. When an || expression has no contextual type, the right operand is contextually typed + // by the type of the left operand, except for the special case of Javascript declarations of the form + // `namespace.prop = namespace.prop || {}`. + const type = getContextualType(binaryExpression, contextFlags); + return node === right && (type && type.pattern || !type && !isDefaultedExpandoInitializer(binaryExpression)) ? + getTypeOfExpression(left) : type; + case SyntaxKind.AmpersandAmpersandToken: + case SyntaxKind.CommaToken: + return node === right ? getContextualType(binaryExpression, contextFlags) : undefined; + default: + return undefined; + } + } + + /** + * Try to find a resolved symbol for an expression without also resolving its type, as + * getSymbolAtLocation would (as that could be reentrant into contextual typing) + */ + function getSymbolForExpression(e: Expression) { + if (canHaveSymbol(e) && e.symbol) { + return e.symbol; + } + if (isIdentifier(e)) { + return getResolvedSymbol(e); + } + if (isPropertyAccessExpression(e)) { + const lhsType = getTypeOfExpression(e.expression); + return isPrivateIdentifier(e.name) ? tryGetPrivateIdentifierPropertyOfType(lhsType, e.name) : getPropertyOfType(lhsType, e.name.escapedText); + } + if (isElementAccessExpression(e)) { + const propType = checkExpressionCached(e.argumentExpression); + if (!isTypeUsableAsPropertyName(propType)) { + return undefined; + } + const lhsType = getTypeOfExpression(e.expression); + return getPropertyOfType(lhsType, getPropertyNameFromType(propType)); + } + return undefined; + + function tryGetPrivateIdentifierPropertyOfType(type: Type, id: PrivateIdentifier) { + const lexicallyScopedSymbol = lookupSymbolForPrivateIdentifierDeclaration(id.escapedText, id); + return lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(type, lexicallyScopedSymbol); + } + } + + // In an assignment expression, the right operand is contextually typed by the type of the left operand. + // Don't do this for assignment declarations unless there is a type tag on the assignment, to avoid circularity from checking the right operand. + function getContextualTypeForAssignmentDeclaration(binaryExpression: BinaryExpression): Type | undefined { + const kind = getAssignmentDeclarationKind(binaryExpression); + switch (kind) { + case AssignmentDeclarationKind.None: + case AssignmentDeclarationKind.ThisProperty: + const lhsSymbol = getSymbolForExpression(binaryExpression.left); + const decl = lhsSymbol && lhsSymbol.valueDeclaration; + // Unannotated, uninitialized property declarations have a type implied by their usage in the constructor. + // We avoid calling back into `getTypeOfExpression` and reentering contextual typing to avoid a bogus circularity error in that case. + if (decl && (isPropertyDeclaration(decl) || isPropertySignature(decl))) { + const overallAnnotation = getEffectiveTypeAnnotationNode(decl); + return (overallAnnotation && instantiateType(getTypeFromTypeNode(overallAnnotation), getSymbolLinks(lhsSymbol).mapper)) || + (isPropertyDeclaration(decl) ? decl.initializer && getTypeOfExpression(binaryExpression.left) : undefined); + } + if (kind === AssignmentDeclarationKind.None) { + return getTypeOfExpression(binaryExpression.left); + } + return getContextualTypeForThisPropertyAssignment(binaryExpression); + case AssignmentDeclarationKind.Property: + if (isPossiblyAliasedThisProperty(binaryExpression, kind)) { + return getContextualTypeForThisPropertyAssignment(binaryExpression); + } + // If `binaryExpression.left` was assigned a symbol, then this is a new declaration; otherwise it is an assignment to an existing declaration. + // See `bindStaticPropertyAssignment` in `binder.ts`. + else if (!canHaveSymbol(binaryExpression.left) || !binaryExpression.left.symbol) { + return getTypeOfExpression(binaryExpression.left); + } + else { + const decl = binaryExpression.left.symbol.valueDeclaration; + if (!decl) { + return undefined; + } + const lhs = cast(binaryExpression.left, isAccessExpression); + const overallAnnotation = getEffectiveTypeAnnotationNode(decl); + if (overallAnnotation) { + return getTypeFromTypeNode(overallAnnotation); + } + else if (isIdentifier(lhs.expression)) { + const id = lhs.expression; + const parentSymbol = resolveName(id, id.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (parentSymbol) { + const annotated = parentSymbol.valueDeclaration && getEffectiveTypeAnnotationNode(parentSymbol.valueDeclaration); + if (annotated) { + const nameStr = getElementOrPropertyAccessName(lhs); + if (nameStr !== undefined) { + return getTypeOfPropertyOfContextualType(getTypeFromTypeNode(annotated), nameStr); + } + } + return undefined; + } + } + return isInJSFile(decl) || decl === binaryExpression.left ? undefined : getTypeOfExpression(binaryExpression.left); + } + case AssignmentDeclarationKind.ExportsProperty: + case AssignmentDeclarationKind.Prototype: + case AssignmentDeclarationKind.PrototypeProperty: + case AssignmentDeclarationKind.ModuleExports: + let valueDeclaration: Declaration | undefined; + if (kind !== AssignmentDeclarationKind.ModuleExports) { + valueDeclaration = canHaveSymbol(binaryExpression.left) ? binaryExpression.left.symbol?.valueDeclaration : undefined; + } + valueDeclaration ||= binaryExpression.symbol?.valueDeclaration; + const annotated = valueDeclaration && getEffectiveTypeAnnotationNode(valueDeclaration); + return annotated ? getTypeFromTypeNode(annotated) : undefined; + case AssignmentDeclarationKind.ObjectDefinePropertyValue: + case AssignmentDeclarationKind.ObjectDefinePropertyExports: + case AssignmentDeclarationKind.ObjectDefinePrototypeProperty: + return Debug.fail("Does not apply"); + default: + return Debug.assertNever(kind); + } + } + + function isPossiblyAliasedThisProperty(declaration: BinaryExpression, kind = getAssignmentDeclarationKind(declaration)) { + if (kind === AssignmentDeclarationKind.ThisProperty) { + return true; + } + if (!isInJSFile(declaration) || kind !== AssignmentDeclarationKind.Property || !isIdentifier((declaration.left as AccessExpression).expression)) { + return false; + } + const name = ((declaration.left as AccessExpression).expression as Identifier).escapedText; + const symbol = resolveName(declaration.left, name, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true, /*excludeGlobals*/ true); + return isThisInitializedDeclaration(symbol?.valueDeclaration); + } + + function getContextualTypeForThisPropertyAssignment(binaryExpression: BinaryExpression): Type | undefined { + if (!binaryExpression.symbol) return getTypeOfExpression(binaryExpression.left); + if (binaryExpression.symbol.valueDeclaration) { + const annotated = getEffectiveTypeAnnotationNode(binaryExpression.symbol.valueDeclaration); + if (annotated) { + const type = getTypeFromTypeNode(annotated); + if (type) { + return type; + } + } + } + const thisAccess = cast(binaryExpression.left, isAccessExpression); + if (!isObjectLiteralMethod(getThisContainer(thisAccess.expression, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false))) { + return undefined; + } + const thisType = checkThisExpression(thisAccess.expression); + const nameStr = getElementOrPropertyAccessName(thisAccess); + return nameStr !== undefined && getTypeOfPropertyOfContextualType(thisType, nameStr) || undefined; + } + + function isCircularMappedProperty(symbol: Symbol) { + return !!(getCheckFlags(symbol) & CheckFlags.Mapped && !(symbol as MappedSymbol).links.type && findResolutionCycleStartIndex(symbol, TypeSystemPropertyName.Type) >= 0); + } + + function getTypeOfPropertyOfContextualType(type: Type, name: __String, nameType?: Type) { + return mapType(type, t => { + if (isGenericMappedType(t) && !t.declaration.nameType) { + const constraint = getConstraintTypeFromMappedType(t); + const constraintOfConstraint = getBaseConstraintOfType(constraint) || constraint; + const propertyNameType = nameType || getStringLiteralType(unescapeLeadingUnderscores(name)); + if (isTypeAssignableTo(propertyNameType, constraintOfConstraint)) { + return substituteIndexedMappedType(t, propertyNameType); + } + } + else if (t.flags & TypeFlags.StructuredType) { + const prop = getPropertyOfType(t, name); + if (prop) { + return isCircularMappedProperty(prop) ? undefined : removeMissingType(getTypeOfSymbol(prop), !!(prop.flags & SymbolFlags.Optional)); + } + if (isTupleType(t) && isNumericLiteralName(name) && +name >= 0) { + const restType = getElementTypeOfSliceOfTupleType(t, t.target.fixedLength, /*endSkipCount*/ 0, /*writing*/ false, /*noReductions*/ true); + if (restType) { + return restType; + } + } + return findApplicableIndexInfo(getIndexInfosOfStructuredType(t), nameType || getStringLiteralType(unescapeLeadingUnderscores(name)))?.type; + } + return undefined; + }, /*noReductions*/ true); + } + + // In an object literal contextually typed by a type T, the contextual type of a property assignment is the type of + // the matching property in T, if one exists. Otherwise, it is the type of the numeric index signature in T, if one + // exists. Otherwise, it is the type of the string index signature in T, if one exists. + function getContextualTypeForObjectLiteralMethod(node: MethodDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + Debug.assert(isObjectLiteralMethod(node)); + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return undefined; + } + return getContextualTypeForObjectLiteralElement(node, contextFlags); + } + + function getContextualTypeForObjectLiteralElement(element: ObjectLiteralElementLike, contextFlags: ContextFlags | undefined) { + const objectLiteral = element.parent as ObjectLiteralExpression; + const propertyAssignmentType = isPropertyAssignment(element) && getContextualTypeForVariableLikeDeclaration(element, contextFlags); + if (propertyAssignmentType) { + return propertyAssignmentType; + } + const type = getApparentTypeOfContextualType(objectLiteral, contextFlags); + if (type) { + if (hasBindableName(element)) { + // For a (non-symbol) computed property, there is no reason to look up the name + // in the type. It will just be "__computed", which does not appear in any + // SymbolTable. + const symbol = getSymbolOfDeclaration(element); + return getTypeOfPropertyOfContextualType(type, symbol.escapedName, getSymbolLinks(symbol).nameType); + } + if (hasDynamicName(element)) { + const name = getNameOfDeclaration(element); + if (name && isComputedPropertyName(name)) { + const exprType = checkExpression(name.expression); + const propType = isTypeUsableAsPropertyName(exprType) && getTypeOfPropertyOfContextualType(type, getPropertyNameFromType(exprType)); + if (propType) { + return propType; + } + } + } + if (element.name) { + const nameType = getLiteralTypeFromPropertyName(element.name); + // We avoid calling getApplicableIndexInfo here because it performs potentially expensive intersection reduction. + return mapType(type, t => findApplicableIndexInfo(getIndexInfosOfStructuredType(t), nameType)?.type, /*noReductions*/ true); + } + } + return undefined; + } + + function getSpreadIndices(elements: readonly Node[]) { + let first, last; + for (let i = 0; i < elements.length; i++) { + if (isSpreadElement(elements[i])) { + first ??= i; + last = i; + } + } + return { first, last }; + } + + function getContextualTypeForElementExpression(type: Type | undefined, index: number, length?: number, firstSpreadIndex?: number, lastSpreadIndex?: number): Type | undefined { + return type && mapType(type, t => { + if (isTupleType(t)) { + // If index is before any spread element and within the fixed part of the contextual tuple type, return + // the type of the contextual tuple element. + if ((firstSpreadIndex === undefined || index < firstSpreadIndex) && index < t.target.fixedLength) { + return removeMissingType(getTypeArguments(t)[index], !!(t.target.elementFlags[index] && ElementFlags.Optional)); + } + // When the length is known and the index is after all spread elements we compute the offset from the element + // to the end and the number of ending fixed elements in the contextual tuple type. + const offset = length !== undefined && (lastSpreadIndex === undefined || index > lastSpreadIndex) ? length - index : 0; + const fixedEndLength = offset > 0 && (t.target.combinedFlags & ElementFlags.Variable) ? getEndElementCount(t.target, ElementFlags.Fixed) : 0; + // If the offset is within the ending fixed part of the contextual tuple type, return the type of the contextual + // tuple element. + if (offset > 0 && offset <= fixedEndLength) { + return getTypeArguments(t)[getTypeReferenceArity(t) - offset]; + } + // Return a union of the possible contextual element types with no subtype reduction. + return getElementTypeOfSliceOfTupleType(t, firstSpreadIndex === undefined ? t.target.fixedLength : Math.min(t.target.fixedLength, firstSpreadIndex), length === undefined || lastSpreadIndex === undefined ? fixedEndLength : Math.min(fixedEndLength, length - lastSpreadIndex), /*writing*/ false, /*noReductions*/ true); + } + // If element index is known and a contextual property with that name exists, return it. Otherwise return the + // iterated or element type of the contextual type. + return (!firstSpreadIndex || index < firstSpreadIndex) && getTypeOfPropertyOfContextualType(t, "" + index as __String) || + getIteratedTypeOrElementType(IterationUse.Element, t, undefinedType, /*errorNode*/ undefined, /*checkAssignability*/ false); + }, /*noReductions*/ true); + } + + // In a contextually typed conditional expression, the true/false expressions are contextually typed by the same type. + function getContextualTypeForConditionalOperand(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const conditional = node.parent as ConditionalExpression; + return node === conditional.whenTrue || node === conditional.whenFalse ? getContextualType(conditional, contextFlags) : undefined; + } + + function getContextualTypeForChildJsxExpression(node: JsxElement, child: JsxChild, contextFlags: ContextFlags | undefined) { + const attributesType = getApparentTypeOfContextualType(node.openingElement.attributes, contextFlags); + // JSX expression is in children of JSX Element, we will look for an "children" attribute (we get the name from JSX.ElementAttributesProperty) + const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + if (!(attributesType && !isTypeAny(attributesType) && jsxChildrenPropertyName && jsxChildrenPropertyName !== "")) { + return undefined; + } + const realChildren = getSemanticJsxChildren(node.children); + const childIndex = realChildren.indexOf(child); + const childFieldType = getTypeOfPropertyOfContextualType(attributesType, jsxChildrenPropertyName); + return childFieldType && (realChildren.length === 1 ? childFieldType : mapType(childFieldType, t => { + if (isArrayLikeType(t)) { + return getIndexedAccessType(t, getNumberLiteralType(childIndex)); + } + else { + return t; + } + }, /*noReductions*/ true)); + } + + function getContextualTypeForJsxExpression(node: JsxExpression, contextFlags: ContextFlags | undefined): Type | undefined { + const exprParent = node.parent; + return isJsxAttributeLike(exprParent) + ? getContextualType(node, contextFlags) + : isJsxElement(exprParent) + ? getContextualTypeForChildJsxExpression(exprParent, node, contextFlags) + : undefined; + } + + function getContextualTypeForJsxAttribute(attribute: JsxAttribute | JsxSpreadAttribute, contextFlags: ContextFlags | undefined): Type | undefined { + // When we trying to resolve JsxOpeningLikeElement as a stateless function element, we will already give its attributes a contextual type + // which is a type of the parameter of the signature we are trying out. + // If there is no contextual type (e.g. we are trying to resolve stateful component), get attributes type from resolving element's tagName + if (isJsxAttribute(attribute)) { + const attributesType = getApparentTypeOfContextualType(attribute.parent, contextFlags); + if (!attributesType || isTypeAny(attributesType)) { + return undefined; + } + return getTypeOfPropertyOfContextualType(attributesType, getEscapedTextOfJsxAttributeName(attribute.name)); + } + else { + return getContextualType(attribute.parent, contextFlags); + } + } + + // Return true if the given expression is possibly a discriminant value. We limit the kinds of + // expressions we check to those that don't depend on their contextual type in order not to cause + // recursive (and possibly infinite) invocations of getContextualType. + function isPossiblyDiscriminantValue(node: Expression): boolean { + switch (node.kind) { + case SyntaxKind.StringLiteral: + case SyntaxKind.NumericLiteral: + case SyntaxKind.BigIntLiteral: + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.TemplateExpression: + case SyntaxKind.TrueKeyword: + case SyntaxKind.FalseKeyword: + case SyntaxKind.NullKeyword: + case SyntaxKind.Identifier: + case SyntaxKind.UndefinedKeyword: + return true; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ParenthesizedExpression: + return isPossiblyDiscriminantValue((node as PropertyAccessExpression | ParenthesizedExpression).expression); + case SyntaxKind.JsxExpression: + return !(node as JsxExpression).expression || isPossiblyDiscriminantValue((node as JsxExpression).expression!); + } + return false; + } + + function discriminateContextualTypeByObjectMembers(node: ObjectLiteralExpression, contextualType: UnionType) { + const key = `D${getNodeId(node)},${getTypeId(contextualType)}`; + return getCachedType(key) ?? setCachedType( + key, + getMatchingUnionConstituentForObjectLiteral(contextualType, node) ?? discriminateTypeByDiscriminableItems( + contextualType, + concatenate( + map( + filter(node.properties, (p): p is PropertyAssignment | ShorthandPropertyAssignment => { + if (!p.symbol) { + return false; + } + if (p.kind === SyntaxKind.PropertyAssignment) { + return isPossiblyDiscriminantValue(p.initializer) && isDiscriminantProperty(contextualType, p.symbol.escapedName); + } + if (p.kind === SyntaxKind.ShorthandPropertyAssignment) { + return isDiscriminantProperty(contextualType, p.symbol.escapedName); + } + return false; + }), + prop => ([() => getContextFreeTypeOfExpression(prop.kind === SyntaxKind.PropertyAssignment ? prop.initializer : prop.name), prop.symbol.escapedName] as const), + ), + map( + filter(getPropertiesOfType(contextualType), s => !!(s.flags & SymbolFlags.Optional) && !!node?.symbol?.members && !node.symbol.members.has(s.escapedName) && isDiscriminantProperty(contextualType, s.escapedName)), + s => [() => undefinedType, s.escapedName] as const, + ), + ), + isTypeAssignableTo, + ), + ); + } + + function discriminateContextualTypeByJSXAttributes(node: JsxAttributes, contextualType: UnionType) { + const key = `D${getNodeId(node)},${getTypeId(contextualType)}`; + const cached = getCachedType(key); + if (cached) return cached; + const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + return setCachedType( + key, + discriminateTypeByDiscriminableItems( + contextualType, + concatenate( + map( + filter(node.properties, p => !!p.symbol && p.kind === SyntaxKind.JsxAttribute && isDiscriminantProperty(contextualType, p.symbol.escapedName) && (!p.initializer || isPossiblyDiscriminantValue(p.initializer))), + prop => ([!(prop as JsxAttribute).initializer ? (() => trueType) : (() => getContextFreeTypeOfExpression((prop as JsxAttribute).initializer!)), prop.symbol.escapedName] as const), + ), + map( + filter(getPropertiesOfType(contextualType), s => { + if (!(s.flags & SymbolFlags.Optional) || !node?.symbol?.members) { + return false; + } + const element = node.parent.parent; + if (s.escapedName === jsxChildrenPropertyName && isJsxElement(element) && getSemanticJsxChildren(element.children).length) { + return false; + } + return !node.symbol.members.has(s.escapedName) && isDiscriminantProperty(contextualType, s.escapedName); + }), + s => [() => undefinedType, s.escapedName] as const, + ), + ), + isTypeAssignableTo, + ), + ); + } + + // Return the contextual type for a given expression node. During overload resolution, a contextual type may temporarily + // be "pushed" onto a node using the contextualType property. + function getApparentTypeOfContextualType(node: Expression | MethodDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + const contextualType = isObjectLiteralMethod(node) ? + getContextualTypeForObjectLiteralMethod(node, contextFlags) : + getContextualType(node, contextFlags); + const instantiatedType = instantiateContextualType(contextualType, node, contextFlags); + if (instantiatedType && !(contextFlags && contextFlags & ContextFlags.NoConstraints && instantiatedType.flags & TypeFlags.TypeVariable)) { + const apparentType = mapType( + instantiatedType, + // When obtaining apparent type of *contextual* type we don't want to get apparent type of mapped types. + // That would evaluate mapped types with array or tuple type constraints too eagerly + // and thus it would prevent `getTypeOfPropertyOfContextualType` from obtaining per-position contextual type for elements of array literal expressions. + // Apparent type of other mapped types is already the mapped type itself so we can just avoid calling `getApparentType` here for all mapped types. + t => getObjectFlags(t) & ObjectFlags.Mapped ? t : getApparentType(t), + /*noReductions*/ true, + ); + return apparentType.flags & TypeFlags.Union && isObjectLiteralExpression(node) ? discriminateContextualTypeByObjectMembers(node, apparentType as UnionType) : + apparentType.flags & TypeFlags.Union && isJsxAttributes(node) ? discriminateContextualTypeByJSXAttributes(node, apparentType as UnionType) : + apparentType; + } + } + + // If the given contextual type contains instantiable types and if a mapper representing + // return type inferences is available, instantiate those types using that mapper. + function instantiateContextualType(contextualType: Type | undefined, node: Node, contextFlags: ContextFlags | undefined): Type | undefined { + if (contextualType && maybeTypeOfKind(contextualType, TypeFlags.Instantiable)) { + const inferenceContext = getInferenceContext(node); + // If no inferences have been made, and none of the type parameters for which we are inferring + // specify default types, nothing is gained from instantiating as type parameters would just be + // replaced with their constraints similar to the apparent type. + if (inferenceContext && contextFlags! & ContextFlags.Signature && some(inferenceContext.inferences, hasInferenceCandidatesOrDefault)) { + // For contextual signatures we incorporate all inferences made so far, e.g. from return + // types as well as arguments to the left in a function call. + return instantiateInstantiableTypes(contextualType, inferenceContext.nonFixingMapper); + } + if (inferenceContext?.returnMapper) { + // For other purposes (e.g. determining whether to produce literal types) we only + // incorporate inferences made from the return type in a function call. We remove + // the 'boolean' type from the contextual type such that contextually typed boolean + // literals actually end up widening to 'boolean' (see #48363). + const type = instantiateInstantiableTypes(contextualType, inferenceContext.returnMapper); + return type.flags & TypeFlags.Union && containsType((type as UnionType).types, regularFalseType) && containsType((type as UnionType).types, regularTrueType) ? + filterType(type, t => t !== regularFalseType && t !== regularTrueType) : + type; + } + } + return contextualType; + } + + // This function is similar to instantiateType, except that (a) it only instantiates types that + // are classified as instantiable (i.e. it doesn't instantiate object types), and (b) it performs + // no reductions on instantiated union types. + function instantiateInstantiableTypes(type: Type, mapper: TypeMapper): Type { + if (type.flags & TypeFlags.Instantiable) { + return instantiateType(type, mapper); + } + if (type.flags & TypeFlags.Union) { + return getUnionType(map((type as UnionType).types, t => instantiateInstantiableTypes(t, mapper)), UnionReduction.None); + } + if (type.flags & TypeFlags.Intersection) { + return getIntersectionType(map((type as IntersectionType).types, t => instantiateInstantiableTypes(t, mapper))); + } + return type; + } + + /** + * Whoa! Do you really want to use this function? + * + * Unless you're trying to get the *non-apparent* type for a + * value-literal type or you're authoring relevant portions of this algorithm, + * you probably meant to use 'getApparentTypeOfContextualType'. + * Otherwise this may not be very useful. + * + * In cases where you *are* working on this function, you should understand + * when it is appropriate to use 'getContextualType' and 'getApparentTypeOfContextualType'. + * + * - Use 'getContextualType' when you are simply going to propagate the result to the expression. + * - Use 'getApparentTypeOfContextualType' when you're going to need the members of the type. + * + * @param node the expression whose contextual type will be returned. + * @returns the contextual type of an expression. + */ + function getContextualType(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return undefined; + } + // Cached contextual types are obtained with no ContextFlags, so we can only consult them for + // requests with no ContextFlags. + const index = findContextualNode(node, /*includeCaches*/ !contextFlags); + if (index >= 0) { + return contextualTypes[index]; + } + const { parent } = node; + switch (parent.kind) { + case SyntaxKind.VariableDeclaration: + case SyntaxKind.Parameter: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + case SyntaxKind.BindingElement: + return getContextualTypeForInitializerExpression(node, contextFlags); + case SyntaxKind.ArrowFunction: + case SyntaxKind.ReturnStatement: + return getContextualTypeForReturnExpression(node, contextFlags); + case SyntaxKind.YieldExpression: + return getContextualTypeForYieldOperand(parent as YieldExpression, contextFlags); + case SyntaxKind.AwaitExpression: + return getContextualTypeForAwaitOperand(parent as AwaitExpression, contextFlags); + case SyntaxKind.CallExpression: + case SyntaxKind.NewExpression: + return getContextualTypeForArgument(parent as CallExpression | NewExpression | Decorator, node); + case SyntaxKind.Decorator: + return getContextualTypeForDecorator(parent as Decorator); + case SyntaxKind.TypeAssertionExpression: + case SyntaxKind.AsExpression: + return isConstTypeReference((parent as AssertionExpression).type) ? getContextualType(parent as AssertionExpression, contextFlags) : getTypeFromTypeNode((parent as AssertionExpression).type); + case SyntaxKind.BinaryExpression: + return getContextualTypeForBinaryOperand(node, contextFlags); + case SyntaxKind.PropertyAssignment: + case SyntaxKind.ShorthandPropertyAssignment: + return getContextualTypeForObjectLiteralElement(parent as PropertyAssignment | ShorthandPropertyAssignment, contextFlags); + case SyntaxKind.SpreadAssignment: + return getContextualType(parent.parent as ObjectLiteralExpression, contextFlags); + case SyntaxKind.ArrayLiteralExpression: { + const arrayLiteral = parent as ArrayLiteralExpression; + const type = getApparentTypeOfContextualType(arrayLiteral, contextFlags); + const elementIndex = indexOfNode(arrayLiteral.elements, node); + const spreadIndices = getNodeLinks(arrayLiteral).spreadIndices ??= getSpreadIndices(arrayLiteral.elements); + return getContextualTypeForElementExpression(type, elementIndex, arrayLiteral.elements.length, spreadIndices.first, spreadIndices.last); + } + case SyntaxKind.ConditionalExpression: + return getContextualTypeForConditionalOperand(node, contextFlags); + case SyntaxKind.TemplateSpan: + Debug.assert(parent.parent.kind === SyntaxKind.TemplateExpression); + return getContextualTypeForSubstitutionExpression(parent.parent as TemplateExpression, node); + case SyntaxKind.ParenthesizedExpression: { + if (isInJSFile(parent)) { + if (isJSDocSatisfiesExpression(parent)) { + return getTypeFromTypeNode(getJSDocSatisfiesExpressionType(parent)); + } + // Like in `checkParenthesizedExpression`, an `/** @type {xyz} */` comment before a parenthesized expression acts as a type cast. + const typeTag = getJSDocTypeTag(parent); + if (typeTag && !isConstTypeReference(typeTag.typeExpression.type)) { + return getTypeFromTypeNode(typeTag.typeExpression.type); + } + } + return getContextualType(parent as ParenthesizedExpression, contextFlags); + } + case SyntaxKind.NonNullExpression: + return getContextualType(parent as NonNullExpression, contextFlags); + case SyntaxKind.SatisfiesExpression: + return getTypeFromTypeNode((parent as SatisfiesExpression).type); + case SyntaxKind.ExportAssignment: + return tryGetTypeFromEffectiveTypeNode(parent as ExportAssignment); + case SyntaxKind.JsxExpression: + return getContextualTypeForJsxExpression(parent as JsxExpression, contextFlags); + case SyntaxKind.JsxAttribute: + case SyntaxKind.JsxSpreadAttribute: + return getContextualTypeForJsxAttribute(parent as JsxAttribute | JsxSpreadAttribute, contextFlags); + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.JsxSelfClosingElement: + return getContextualJsxElementAttributesType(parent as JsxOpeningLikeElement, contextFlags); + case SyntaxKind.ImportAttribute: + return getContextualImportAttributeType(parent as ImportAttribute); + } + return undefined; + } + + function pushCachedContextualType(node: Expression) { + pushContextualType(node, getContextualType(node, /*contextFlags*/ undefined), /*isCache*/ true); + } + + function pushContextualType(node: Expression, type: Type | undefined, isCache: boolean) { + contextualTypeNodes[contextualTypeCount] = node; + contextualTypes[contextualTypeCount] = type; + contextualIsCache[contextualTypeCount] = isCache; + contextualTypeCount++; + } + + function popContextualType() { + contextualTypeCount--; + } + + function findContextualNode(node: Node, includeCaches: boolean) { + for (let i = contextualTypeCount - 1; i >= 0; i--) { + if (node === contextualTypeNodes[i] && (includeCaches || !contextualIsCache[i])) { + return i; + } + } + return -1; + } + + function pushInferenceContext(node: Node, inferenceContext: InferenceContext | undefined) { + inferenceContextNodes[inferenceContextCount] = node; + inferenceContexts[inferenceContextCount] = inferenceContext; + inferenceContextCount++; + } + + function popInferenceContext() { + inferenceContextCount--; + } + + function getInferenceContext(node: Node) { + for (let i = inferenceContextCount - 1; i >= 0; i--) { + if (isNodeDescendantOf(node, inferenceContextNodes[i])) { + return inferenceContexts[i]; + } + } + } + + function getContextualImportAttributeType(node: ImportAttribute) { + return getTypeOfPropertyOfContextualType(getGlobalImportAttributesType(/*reportErrors*/ false), getNameFromImportAttribute(node)); + } + + function getContextualJsxElementAttributesType(node: JsxOpeningLikeElement, contextFlags: ContextFlags | undefined) { + if (isJsxOpeningElement(node) && contextFlags !== ContextFlags.Completions) { + const index = findContextualNode(node.parent, /*includeCaches*/ !contextFlags); + if (index >= 0) { + // Contextually applied type is moved from attributes up to the outer jsx attributes so when walking up from the children they get hit + // _However_ to hit them from the _attributes_ we must look for them here; otherwise we'll used the declared type + // (as below) instead! + return contextualTypes[index]; + } + } + return getContextualTypeForArgumentAtIndex(node, 0); + } + + function getEffectiveFirstArgumentForJsxSignature(signature: Signature, node: JsxOpeningLikeElement) { + return getJsxReferenceKind(node) !== JsxReferenceKind.Component + ? getJsxPropsTypeFromCallSignature(signature, node) + : getJsxPropsTypeFromClassType(signature, node); + } + + function getJsxPropsTypeFromCallSignature(sig: Signature, context: JsxOpeningLikeElement) { + let propsType = getTypeOfFirstParameterOfSignatureWithFallback(sig, unknownType); + propsType = getJsxManagedAttributesFromLocatedAttributes(context, getJsxNamespaceAt(context), propsType); + const intrinsicAttribs = getJsxType(JsxNames.IntrinsicAttributes, context); + if (!isErrorType(intrinsicAttribs)) { + propsType = intersectTypes(intrinsicAttribs, propsType); + } + return propsType; + } + + function getJsxPropsTypeForSignatureFromMember(sig: Signature, forcedLookupLocation: __String) { + if (sig.compositeSignatures) { + // JSX Elements using the legacy `props`-field based lookup (eg, react class components) need to treat the `props` member as an input + // instead of an output position when resolving the signature. We need to go back to the input signatures of the composite signature, + // get the type of `props` on each return type individually, and then _intersect them_, rather than union them (as would normally occur + // for a union signature). It's an unfortunate quirk of looking in the output of the signature for the type we want to use for the input. + // The default behavior of `getTypeOfFirstParameterOfSignatureWithFallback` when no `props` member name is defined is much more sane. + const results: Type[] = []; + for (const signature of sig.compositeSignatures) { + const instance = getReturnTypeOfSignature(signature); + if (isTypeAny(instance)) { + return instance; + } + const propType = getTypeOfPropertyOfType(instance, forcedLookupLocation); + if (!propType) { + return; + } + results.push(propType); + } + return getIntersectionType(results); // Same result for both union and intersection signatures + } + const instanceType = getReturnTypeOfSignature(sig); + return isTypeAny(instanceType) ? instanceType : getTypeOfPropertyOfType(instanceType, forcedLookupLocation); + } + + function getStaticTypeOfReferencedJsxConstructor(context: JsxOpeningLikeElement) { + if (isJsxIntrinsicTagName(context.tagName)) { + const result = getIntrinsicAttributesTypeFromJsxOpeningLikeElement(context); + const fakeSignature = createSignatureForJSXIntrinsic(context, result); + return getOrCreateTypeFromSignature(fakeSignature); + } + const tagType = checkExpressionCached(context.tagName); + if (tagType.flags & TypeFlags.StringLiteral) { + const result = getIntrinsicAttributesTypeFromStringLiteralType(tagType as StringLiteralType, context); + if (!result) { + return errorType; + } + const fakeSignature = createSignatureForJSXIntrinsic(context, result); + return getOrCreateTypeFromSignature(fakeSignature); + } + return tagType; + } + + function getJsxManagedAttributesFromLocatedAttributes(context: JsxOpeningLikeElement, ns: Symbol, attributesType: Type) { + const managedSym = getJsxLibraryManagedAttributes(ns); + if (managedSym) { + const ctorType = getStaticTypeOfReferencedJsxConstructor(context); + const result = instantiateAliasOrInterfaceWithDefaults(managedSym, isInJSFile(context), ctorType, attributesType); + if (result) { + return result; + } + } + return attributesType; + } + + function getJsxPropsTypeFromClassType(sig: Signature, context: JsxOpeningLikeElement) { + const ns = getJsxNamespaceAt(context); + const forcedLookupLocation = getJsxElementPropertiesName(ns); + let attributesType = forcedLookupLocation === undefined + // If there is no type ElementAttributesProperty, return the type of the first parameter of the signature, which should be the props type + ? getTypeOfFirstParameterOfSignatureWithFallback(sig, unknownType) + : forcedLookupLocation === "" + // If there is no e.g. 'props' member in ElementAttributesProperty, use the element class type instead + ? getReturnTypeOfSignature(sig) + // Otherwise get the type of the property on the signature return type + : getJsxPropsTypeForSignatureFromMember(sig, forcedLookupLocation); + + if (!attributesType) { + // There is no property named 'props' on this instance type + if (!!forcedLookupLocation && !!length(context.attributes.properties)) { + error(context, Diagnostics.JSX_element_class_does_not_support_attributes_because_it_does_not_have_a_0_property, unescapeLeadingUnderscores(forcedLookupLocation)); + } + return unknownType; + } + + attributesType = getJsxManagedAttributesFromLocatedAttributes(context, ns, attributesType); + + if (isTypeAny(attributesType)) { + // Props is of type 'any' or unknown + return attributesType; + } + else { + // Normal case -- add in IntrinsicClassElements and IntrinsicElements + let apparentAttributesType = attributesType; + const intrinsicClassAttribs = getJsxType(JsxNames.IntrinsicClassAttributes, context); + if (!isErrorType(intrinsicClassAttribs)) { + const typeParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(intrinsicClassAttribs.symbol); + const hostClassType = getReturnTypeOfSignature(sig); + let libraryManagedAttributeType: Type; + if (typeParams) { + // apply JSX.IntrinsicClassElements + const inferredArgs = fillMissingTypeArguments([hostClassType], typeParams, getMinTypeArgumentCount(typeParams), isInJSFile(context)); + libraryManagedAttributeType = instantiateType(intrinsicClassAttribs, createTypeMapper(typeParams, inferredArgs)); + } + // or JSX.IntrinsicClassElements has no generics. + else libraryManagedAttributeType = intrinsicClassAttribs; + apparentAttributesType = intersectTypes(libraryManagedAttributeType, apparentAttributesType); + } + + const intrinsicAttribs = getJsxType(JsxNames.IntrinsicAttributes, context); + if (!isErrorType(intrinsicAttribs)) { + apparentAttributesType = intersectTypes(intrinsicAttribs, apparentAttributesType); + } + + return apparentAttributesType; + } + } + + function getIntersectedSignatures(signatures: readonly Signature[]) { + return getStrictOptionValue(compilerOptions, "noImplicitAny") + ? reduceLeft( + signatures, + (left: Signature | undefined, right) => + left === right || !left ? left + : compareTypeParametersIdentical(left.typeParameters, right!.typeParameters) ? combineSignaturesOfIntersectionMembers(left, right!) + : undefined, + ) + : undefined; + } + + function combineIntersectionThisParam(left: Symbol | undefined, right: Symbol | undefined, mapper: TypeMapper | undefined): Symbol | undefined { + if (!left || !right) { + return left || right; + } + // A signature `this` type might be a read or a write position... It's very possible that it should be invariant + // and we should refuse to merge signatures if there are `this` types and they do not match. However, so as to be + // pessimistic when contextual typing, for now, we'll union the `this` types. + const thisType = getUnionType([getTypeOfSymbol(left), instantiateType(getTypeOfSymbol(right), mapper)]); + return createSymbolWithType(left, thisType); + } + + function combineIntersectionParameters(left: Signature, right: Signature, mapper: TypeMapper | undefined) { + const leftCount = getParameterCount(left); + const rightCount = getParameterCount(right); + const longest = leftCount >= rightCount ? left : right; + const shorter = longest === left ? right : left; + const longestCount = longest === left ? leftCount : rightCount; + const eitherHasEffectiveRest = hasEffectiveRestParameter(left) || hasEffectiveRestParameter(right); + const needsExtraRestElement = eitherHasEffectiveRest && !hasEffectiveRestParameter(longest); + const params = new Array(longestCount + (needsExtraRestElement ? 1 : 0)); + for (let i = 0; i < longestCount; i++) { + let longestParamType = tryGetTypeAtPosition(longest, i)!; + if (longest === right) { + longestParamType = instantiateType(longestParamType, mapper); + } + let shorterParamType = tryGetTypeAtPosition(shorter, i) || unknownType; + if (shorter === right) { + shorterParamType = instantiateType(shorterParamType, mapper); + } + const unionParamType = getUnionType([longestParamType, shorterParamType]); + const isRestParam = eitherHasEffectiveRest && !needsExtraRestElement && i === (longestCount - 1); + const isOptional = i >= getMinArgumentCount(longest) && i >= getMinArgumentCount(shorter); + const leftName = i >= leftCount ? undefined : getParameterNameAtPosition(left, i); + const rightName = i >= rightCount ? undefined : getParameterNameAtPosition(right, i); + + const paramName = leftName === rightName ? leftName : + !leftName ? rightName : + !rightName ? leftName : + undefined; + const paramSymbol = createSymbol( + SymbolFlags.FunctionScopedVariable | (isOptional && !isRestParam ? SymbolFlags.Optional : 0), + paramName || `arg${i}` as __String, + ); + paramSymbol.links.type = isRestParam ? createArrayType(unionParamType) : unionParamType; + params[i] = paramSymbol; + } + if (needsExtraRestElement) { + const restParamSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "args" as __String); + restParamSymbol.links.type = createArrayType(getTypeAtPosition(shorter, longestCount)); + if (shorter === right) { + restParamSymbol.links.type = instantiateType(restParamSymbol.links.type, mapper); + } + params[longestCount] = restParamSymbol; + } + return params; + } + + function combineSignaturesOfIntersectionMembers(left: Signature, right: Signature): Signature { + const typeParams = left.typeParameters || right.typeParameters; + let paramMapper: TypeMapper | undefined; + if (left.typeParameters && right.typeParameters) { + paramMapper = createTypeMapper(right.typeParameters, left.typeParameters); + // We just use the type parameter defaults from the first signature + } + const declaration = left.declaration; + const params = combineIntersectionParameters(left, right, paramMapper); + const thisParam = combineIntersectionThisParam(left.thisParameter, right.thisParameter, paramMapper); + const minArgCount = Math.max(left.minArgumentCount, right.minArgumentCount); + const result = createSignature( + declaration, + typeParams, + thisParam, + params, + /*resolvedReturnType*/ undefined, + /*resolvedTypePredicate*/ undefined, + minArgCount, + (left.flags | right.flags) & SignatureFlags.PropagatingFlags, + ); + result.compositeKind = TypeFlags.Intersection; + result.compositeSignatures = concatenate(left.compositeKind === TypeFlags.Intersection && left.compositeSignatures || [left], [right]); + if (paramMapper) { + result.mapper = left.compositeKind === TypeFlags.Intersection && left.mapper && left.compositeSignatures ? combineTypeMappers(left.mapper, paramMapper) : paramMapper; + } + return result; + } + + // If the given type is an object or union type with a single signature, and if that signature has at + // least as many parameters as the given function, return the signature. Otherwise return undefined. + function getContextualCallSignature(type: Type, node: SignatureDeclaration): Signature | undefined { + const signatures = getSignaturesOfType(type, SignatureKind.Call); + const applicableByArity = filter(signatures, s => !isAritySmaller(s, node)); + return applicableByArity.length === 1 ? applicableByArity[0] : getIntersectedSignatures(applicableByArity); + } + + /** If the contextual signature has fewer parameters than the function expression, do not use it */ + function isAritySmaller(signature: Signature, target: SignatureDeclaration) { + let targetParameterCount = 0; + for (; targetParameterCount < target.parameters.length; targetParameterCount++) { + const param = target.parameters[targetParameterCount]; + if (param.initializer || param.questionToken || param.dotDotDotToken || isJSDocOptionalParameter(param)) { + break; + } + } + if (target.parameters.length && parameterIsThisKeyword(target.parameters[0])) { + targetParameterCount--; + } + return !hasEffectiveRestParameter(signature) && getParameterCount(signature) < targetParameterCount; + } + + function getContextualSignatureForFunctionLikeDeclaration(node: FunctionLikeDeclaration): Signature | undefined { + // Only function expressions, arrow functions, and object literal methods are contextually typed. + return isFunctionExpressionOrArrowFunction(node) || isObjectLiteralMethod(node) + ? getContextualSignature(node as FunctionExpression) + : undefined; + } + + // Return the contextual signature for a given expression node. A contextual type provides a + // contextual signature if it has a single call signature and if that call signature is non-generic. + // If the contextual type is a union type, get the signature from each type possible and if they are + // all identical ignoring their return type, the result is same signature but with return type as + // union type of return types from these signatures + function getContextualSignature(node: FunctionExpression | ArrowFunction | MethodDeclaration): Signature | undefined { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + const typeTagSignature = getSignatureOfTypeTag(node); + if (typeTagSignature) { + return typeTagSignature; + } + const type = getApparentTypeOfContextualType(node, ContextFlags.Signature); + if (!type) { + return undefined; + } + if (!(type.flags & TypeFlags.Union)) { + return getContextualCallSignature(type, node); + } + let signatureList: Signature[] | undefined; + const types = (type as UnionType).types; + for (const current of types) { + const signature = getContextualCallSignature(current, node); + if (signature) { + if (!signatureList) { + // This signature will contribute to contextual union signature + signatureList = [signature]; + } + else if (!compareSignaturesIdentical(signatureList[0], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ true, /*ignoreReturnTypes*/ true, compareTypesIdentical)) { + // Signatures aren't identical, do not use + return undefined; + } + else { + // Use this signature for contextual union signature + signatureList.push(signature); + } + } + } + // Result is union of signatures collected (return type is union of return types of this signature set) + if (signatureList) { + return signatureList.length === 1 ? signatureList[0] : createUnionSignature(signatureList[0], signatureList); + } + } + + function checkGrammarRegularExpressionLiteral(node: RegularExpressionLiteral) { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile) && !node.isUnterminated) { + let lastError: DiagnosticWithLocation | undefined; + scanner ??= createScanner(ScriptTarget.ESNext, /*skipTrivia*/ true); + scanner.setScriptTarget(sourceFile.languageVersion); + scanner.setLanguageVariant(sourceFile.languageVariant); + scanner.setOnError((message, length, arg0) => { + // For providing spelling suggestions + const start = scanner!.getTokenEnd(); + if (message.category === DiagnosticCategory.Message && lastError && start === lastError.start && length === lastError.length) { + const error = createDetachedDiagnostic(sourceFile.fileName, sourceFile.text, start, length, message, arg0); + addRelatedInfo(lastError, error); + } + else if (!lastError || start !== lastError.start) { + lastError = createFileDiagnostic(sourceFile, start, length, message, arg0); + diagnostics.add(lastError); + } + }); + scanner.setText(sourceFile.text, node.pos, node.end - node.pos); + try { + scanner.scan(); + Debug.assert(scanner.reScanSlashToken(/*reportErrors*/ true) === SyntaxKind.RegularExpressionLiteral, "Expected scanner to rescan RegularExpressionLiteral"); + return !!lastError; + } + finally { + scanner.setText(""); + scanner.setOnError(/*onError*/ undefined); + } + } + return false; + } + + function checkRegularExpressionLiteral(node: RegularExpressionLiteral) { + const nodeLinks = getNodeLinks(node); + if (!(nodeLinks.flags & NodeCheckFlags.TypeChecked)) { + nodeLinks.flags |= NodeCheckFlags.TypeChecked; + addLazyDiagnostic(() => checkGrammarRegularExpressionLiteral(node)); + } + return globalRegExpType; + } + + function checkSpreadExpression(node: SpreadElement, checkMode?: CheckMode): Type { + if (languageVersion < LanguageFeatureMinimumTarget.SpreadElements) { + checkExternalEmitHelpers(node, compilerOptions.downlevelIteration ? ExternalEmitHelpers.SpreadIncludes : ExternalEmitHelpers.SpreadArray); + } + + const arrayOrIterableType = checkExpression(node.expression, checkMode); + return checkIteratedTypeOrElementType(IterationUse.Spread, arrayOrIterableType, undefinedType, node.expression); + } + + function checkSyntheticExpression(node: SyntheticExpression): Type { + return node.isSpread ? getIndexedAccessType(node.type, numberType) : node.type; + } + + function hasDefaultValue(node: BindingElement | Expression): boolean { + return (node.kind === SyntaxKind.BindingElement && !!(node as BindingElement).initializer) || + (node.kind === SyntaxKind.BinaryExpression && (node as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken); + } + + function isSpreadIntoCallOrNew(node: ArrayLiteralExpression) { + const parent = walkUpParenthesizedExpressions(node.parent); + return isSpreadElement(parent) && isCallOrNewExpression(parent.parent); + } + + function checkArrayLiteral(node: ArrayLiteralExpression, checkMode: CheckMode | undefined, forceTuple: boolean | undefined): Type { + const elements = node.elements; + const elementCount = elements.length; + const elementTypes: Type[] = []; + const elementFlags: ElementFlags[] = []; + pushCachedContextualType(node); + const inDestructuringPattern = isAssignmentTarget(node); + const inConstContext = isConstContext(node); + const contextualType = getApparentTypeOfContextualType(node, /*contextFlags*/ undefined); + const inTupleContext = isSpreadIntoCallOrNew(node) || !!contextualType && someType(contextualType, t => isTupleLikeType(t) || isGenericMappedType(t) && !t.nameType && !!getHomomorphicTypeVariable(t.target as MappedType || t)); + + let hasOmittedExpression = false; + for (let i = 0; i < elementCount; i++) { + const e = elements[i]; + if (e.kind === SyntaxKind.SpreadElement) { + if (languageVersion < LanguageFeatureMinimumTarget.SpreadElements) { + checkExternalEmitHelpers(e, compilerOptions.downlevelIteration ? ExternalEmitHelpers.SpreadIncludes : ExternalEmitHelpers.SpreadArray); + } + const spreadType = checkExpression((e as SpreadElement).expression, checkMode, forceTuple); + if (isArrayLikeType(spreadType)) { + elementTypes.push(spreadType); + elementFlags.push(ElementFlags.Variadic); + } + else if (inDestructuringPattern) { + // Given the following situation: + // var c: {}; + // [...c] = ["", 0]; + // + // c is represented in the tree as a spread element in an array literal. + // But c really functions as a rest element, and its purpose is to provide + // a contextual type for the right hand side of the assignment. Therefore, + // instead of calling checkExpression on "...c", which will give an error + // if c is not iterable/array-like, we need to act as if we are trying to + // get the contextual element type from it. So we do something similar to + // getContextualTypeForElementExpression, which will crucially not error + // if there is no index type / iterated type. + const restElementType = getIndexTypeOfType(spreadType, numberType) || + getIteratedTypeOrElementType(IterationUse.Destructuring, spreadType, undefinedType, /*errorNode*/ undefined, /*checkAssignability*/ false) || + unknownType; + elementTypes.push(restElementType); + elementFlags.push(ElementFlags.Rest); + } + else { + elementTypes.push(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, (e as SpreadElement).expression)); + elementFlags.push(ElementFlags.Rest); + } + } + else if (exactOptionalPropertyTypes && e.kind === SyntaxKind.OmittedExpression) { + hasOmittedExpression = true; + elementTypes.push(undefinedOrMissingType); + elementFlags.push(ElementFlags.Optional); + } + else { + const type = checkExpressionForMutableLocation(e, checkMode, forceTuple); + elementTypes.push(addOptionality(type, /*isProperty*/ true, hasOmittedExpression)); + elementFlags.push(hasOmittedExpression ? ElementFlags.Optional : ElementFlags.Required); + if (inTupleContext && checkMode && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && isContextSensitive(e)) { + const inferenceContext = getInferenceContext(node); + Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context + addIntraExpressionInferenceSite(inferenceContext, e, type); + } + } + } + popContextualType(); + if (inDestructuringPattern) { + return createTupleType(elementTypes, elementFlags); + } + if (forceTuple || inConstContext || inTupleContext) { + return createArrayLiteralType(createTupleType(elementTypes, elementFlags, /*readonly*/ inConstContext && !(contextualType && someType(contextualType, isMutableArrayLikeType)))); + } + return createArrayLiteralType(createArrayType( + elementTypes.length ? + getUnionType(sameMap(elementTypes, (t, i) => elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessTypeOrUndefined(t, numberType) || anyType : t), UnionReduction.Subtype) : + strictNullChecks ? implicitNeverType : undefinedWideningType, + inConstContext, + )); + } + + function createArrayLiteralType(type: Type) { + if (!(getObjectFlags(type) & ObjectFlags.Reference)) { + return type; + } + let literalType = (type as TypeReference).literalType; + if (!literalType) { + literalType = (type as TypeReference).literalType = cloneTypeReference(type as TypeReference); + literalType.objectFlags |= ObjectFlags.ArrayLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + } + return literalType; + } + + function isNumericName(name: DeclarationName): boolean { + switch (name.kind) { + case SyntaxKind.ComputedPropertyName: + return isNumericComputedName(name); + case SyntaxKind.Identifier: + return isNumericLiteralName(name.escapedText); + case SyntaxKind.NumericLiteral: + case SyntaxKind.StringLiteral: + return isNumericLiteralName(name.text); + default: + return false; + } + } + + function isNumericComputedName(name: ComputedPropertyName): boolean { + // It seems odd to consider an expression of type Any to result in a numeric name, + // but this behavior is consistent with checkIndexedAccess + return isTypeAssignableToKind(checkComputedPropertyName(name), TypeFlags.NumberLike); + } + + function checkComputedPropertyName(node: ComputedPropertyName): Type { + const links = getNodeLinks(node.expression); + if (!links.resolvedType) { + if ( + (isTypeLiteralNode(node.parent.parent) || isClassLike(node.parent.parent) || isInterfaceDeclaration(node.parent.parent)) + && isBinaryExpression(node.expression) && node.expression.operatorToken.kind === SyntaxKind.InKeyword + && node.parent.kind !== SyntaxKind.GetAccessor && node.parent.kind !== SyntaxKind.SetAccessor + ) { + return links.resolvedType = errorType; + } + links.resolvedType = checkExpression(node.expression); + // The computed property name of a non-static class field within a loop must be stored in a block-scoped binding. + // (It needs to be bound at class evaluation time.) + if (isPropertyDeclaration(node.parent) && !hasStaticModifier(node.parent) && isClassExpression(node.parent.parent)) { + const container = getEnclosingBlockScopeContainer(node.parent.parent); + const enclosingIterationStatement = getEnclosingIterationStatement(container); + if (enclosingIterationStatement) { + // The computed field name will use a block scoped binding which can be unique for each iteration of the loop. + getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; + // The generated variable which stores the computed field name must be block-scoped. + getNodeLinks(node).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + // The generated variable which stores the class must be block-scoped. + getNodeLinks(node.parent.parent).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + } + } + // This will allow types number, string, symbol or any. It will also allow enums, the unknown + // type, and any union of these types (like string | number). + if ( + links.resolvedType.flags & TypeFlags.Nullable || + !isTypeAssignableToKind(links.resolvedType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike) && + !isTypeAssignableTo(links.resolvedType, stringNumberSymbolType) + ) { + error(node, Diagnostics.A_computed_property_name_must_be_of_type_string_number_symbol_or_any); + } + } + + return links.resolvedType; + } + + function isSymbolWithNumericName(symbol: Symbol) { + const firstDecl = symbol.declarations?.[0]; + return isNumericLiteralName(symbol.escapedName) || (firstDecl && isNamedDeclaration(firstDecl) && isNumericName(firstDecl.name)); + } + + function isSymbolWithSymbolName(symbol: Symbol) { + const firstDecl = symbol.declarations?.[0]; + return isKnownSymbol(symbol) || (firstDecl && isNamedDeclaration(firstDecl) && isComputedPropertyName(firstDecl.name) && + isTypeAssignableToKind(checkComputedPropertyName(firstDecl.name), TypeFlags.ESSymbol)); + } + + function getObjectLiteralIndexInfo(node: ObjectLiteralExpression, offset: number, properties: Symbol[], keyType: Type): IndexInfo { + const propTypes: Type[] = []; + for (let i = offset; i < properties.length; i++) { + const prop = properties[i]; + if ( + keyType === stringType && !isSymbolWithSymbolName(prop) || + keyType === numberType && isSymbolWithNumericName(prop) || + keyType === esSymbolType && isSymbolWithSymbolName(prop) + ) { + propTypes.push(getTypeOfSymbol(properties[i])); + } + } + const unionType = propTypes.length ? getUnionType(propTypes, UnionReduction.Subtype) : undefinedType; + return createIndexInfo(keyType, unionType, isConstContext(node)); + } + + function getImmediateAliasedSymbol(symbol: Symbol): Symbol | undefined { + Debug.assert((symbol.flags & SymbolFlags.Alias) !== 0, "Should only get Alias here."); + const links = getSymbolLinks(symbol); + if (!links.immediateTarget) { + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + links.immediateTarget = getTargetOfAliasDeclaration(node, /*dontRecursivelyResolve*/ true); + } + + return links.immediateTarget; + } + + function checkObjectLiteral(node: ObjectLiteralExpression, checkMode: CheckMode = CheckMode.Normal): Type { + const inDestructuringPattern = isAssignmentTarget(node); + // Grammar checking + checkGrammarObjectLiteralExpression(node, inDestructuringPattern); + + const allPropertiesTable = strictNullChecks ? createSymbolTable() : undefined; + let propertiesTable = createSymbolTable(); + let propertiesArray: Symbol[] = []; + let spread: Type = emptyObjectType; + + pushCachedContextualType(node); + const contextualType = getApparentTypeOfContextualType(node, /*contextFlags*/ undefined); + const contextualTypeHasPattern = contextualType && contextualType.pattern && + (contextualType.pattern.kind === SyntaxKind.ObjectBindingPattern || contextualType.pattern.kind === SyntaxKind.ObjectLiteralExpression); + const inConstContext = isConstContext(node); + const checkFlags = inConstContext ? CheckFlags.Readonly : 0; + const isInJavascript = isInJSFile(node) && !isInJsonFile(node); + const enumTag = isInJavascript ? getJSDocEnumTag(node) : undefined; + const isJSObjectLiteral = !contextualType && isInJavascript && !enumTag; + let objectFlags: ObjectFlags = ObjectFlags.FreshLiteral; + let patternWithComputedProperties = false; + let hasComputedStringProperty = false; + let hasComputedNumberProperty = false; + let hasComputedSymbolProperty = false; + + // Spreads may cause an early bail; ensure computed names are always checked (this is cached) + // As otherwise they may not be checked until exports for the type at this position are retrieved, + // which may never occur. + for (const elem of node.properties) { + if (elem.name && isComputedPropertyName(elem.name)) { + checkComputedPropertyName(elem.name); + } + } + + let offset = 0; + for (const memberDecl of node.properties) { + let member = getSymbolOfDeclaration(memberDecl); + const computedNameType = memberDecl.name && memberDecl.name.kind === SyntaxKind.ComputedPropertyName ? + checkComputedPropertyName(memberDecl.name) : undefined; + if ( + memberDecl.kind === SyntaxKind.PropertyAssignment || + memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment || + isObjectLiteralMethod(memberDecl) + ) { + let type = memberDecl.kind === SyntaxKind.PropertyAssignment ? checkPropertyAssignment(memberDecl, checkMode) : + // avoid resolving the left side of the ShorthandPropertyAssignment outside of the destructuring + // for error recovery purposes. For example, if a user wrote `{ a = 100 }` instead of `{ a: 100 }`. + // we don't want to say "could not find 'a'". + memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment ? checkExpressionForMutableLocation(!inDestructuringPattern && memberDecl.objectAssignmentInitializer ? memberDecl.objectAssignmentInitializer : memberDecl.name, checkMode) : + checkObjectLiteralMethod(memberDecl, checkMode); + if (isInJavascript) { + const jsDocType = getTypeForDeclarationFromJSDocComment(memberDecl); + if (jsDocType) { + checkTypeAssignableTo(type, jsDocType, memberDecl); + type = jsDocType; + } + else if (enumTag && enumTag.typeExpression) { + checkTypeAssignableTo(type, getTypeFromTypeNode(enumTag.typeExpression), memberDecl); + } + } + objectFlags |= getObjectFlags(type) & ObjectFlags.PropagatingFlags; + const nameType = computedNameType && isTypeUsableAsPropertyName(computedNameType) ? computedNameType : undefined; + const prop = nameType ? + createSymbol(SymbolFlags.Property | member.flags, getPropertyNameFromType(nameType), checkFlags | CheckFlags.Late) : + createSymbol(SymbolFlags.Property | member.flags, member.escapedName, checkFlags); + if (nameType) { + prop.links.nameType = nameType; + } + + if (inDestructuringPattern) { + // If object literal is an assignment pattern and if the assignment pattern specifies a default value + // for the property, make the property optional. + const isOptional = (memberDecl.kind === SyntaxKind.PropertyAssignment && hasDefaultValue(memberDecl.initializer)) || + (memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment && memberDecl.objectAssignmentInitializer); + if (isOptional) { + prop.flags |= SymbolFlags.Optional; + } + } + else if (contextualTypeHasPattern && !(getObjectFlags(contextualType) & ObjectFlags.ObjectLiteralPatternWithComputedProperties)) { + // If object literal is contextually typed by the implied type of a binding pattern, and if the + // binding pattern specifies a default value for the property, make the property optional. + const impliedProp = getPropertyOfType(contextualType, member.escapedName); + if (impliedProp) { + prop.flags |= impliedProp.flags & SymbolFlags.Optional; + } + else if (!getIndexInfoOfType(contextualType, stringType)) { + error(memberDecl.name, Diagnostics.Object_literal_may_only_specify_known_properties_and_0_does_not_exist_in_type_1, symbolToString(member), typeToString(contextualType)); + } + } + + prop.declarations = member.declarations; + prop.parent = member.parent; + if (member.valueDeclaration) { + prop.valueDeclaration = member.valueDeclaration; + } + + prop.links.type = type; + prop.links.target = member; + member = prop; + allPropertiesTable?.set(prop.escapedName, prop); + + if ( + contextualType && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && + (memberDecl.kind === SyntaxKind.PropertyAssignment || memberDecl.kind === SyntaxKind.MethodDeclaration) && isContextSensitive(memberDecl) + ) { + const inferenceContext = getInferenceContext(node); + Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context + const inferenceNode = memberDecl.kind === SyntaxKind.PropertyAssignment ? memberDecl.initializer : memberDecl; + addIntraExpressionInferenceSite(inferenceContext, inferenceNode, type); + } + } + else if (memberDecl.kind === SyntaxKind.SpreadAssignment) { + if (languageVersion < LanguageFeatureMinimumTarget.ObjectAssign) { + checkExternalEmitHelpers(memberDecl, ExternalEmitHelpers.Assign); + } + if (propertiesArray.length > 0) { + spread = getSpreadType(spread, createObjectLiteralType(), node.symbol, objectFlags, inConstContext); + propertiesArray = []; + propertiesTable = createSymbolTable(); + hasComputedStringProperty = false; + hasComputedNumberProperty = false; + hasComputedSymbolProperty = false; + } + const type = getReducedType(checkExpression(memberDecl.expression, checkMode & CheckMode.Inferential)); + if (isValidSpreadType(type)) { + const mergedType = tryMergeUnionOfObjectTypeAndEmptyObject(type, inConstContext); + if (allPropertiesTable) { + checkSpreadPropOverrides(mergedType, allPropertiesTable, memberDecl); + } + offset = propertiesArray.length; + if (isErrorType(spread)) { + continue; + } + spread = getSpreadType(spread, mergedType, node.symbol, objectFlags, inConstContext); + } + else { + error(memberDecl, Diagnostics.Spread_types_may_only_be_created_from_object_types); + spread = errorType; + } + continue; + } + else { + // TypeScript 1.0 spec (April 2014) + // A get accessor declaration is processed in the same manner as + // an ordinary function declaration(section 6.1) with no parameters. + // A set accessor declaration is processed in the same manner + // as an ordinary function declaration with a single parameter and a Void return type. + Debug.assert(memberDecl.kind === SyntaxKind.GetAccessor || memberDecl.kind === SyntaxKind.SetAccessor); + checkNodeDeferred(memberDecl); + } + + if (computedNameType && !(computedNameType.flags & TypeFlags.StringOrNumberLiteralOrUnique)) { + if (isTypeAssignableTo(computedNameType, stringNumberSymbolType)) { + if (isTypeAssignableTo(computedNameType, numberType)) { + hasComputedNumberProperty = true; + } + else if (isTypeAssignableTo(computedNameType, esSymbolType)) { + hasComputedSymbolProperty = true; + } + else { + hasComputedStringProperty = true; + } + if (inDestructuringPattern) { + patternWithComputedProperties = true; + } + } + } + else { + propertiesTable.set(member.escapedName, member); + } + propertiesArray.push(member); + } + popContextualType(); + + // If object literal is contextually typed by the implied type of a binding pattern, augment the result + // type with those properties for which the binding pattern specifies a default value. + // If the object literal is spread into another object literal, skip this step and let the top-level object + // literal handle it instead. Note that this might require full traversal to the root pattern's parent + // as it's the guaranteed to be the common ancestor of the pattern node and the current object node. + // It's not possible to check if the immediate parent node is a spread assignment + // since the type flows in non-obvious ways through conditional expressions, IIFEs and more. + if (contextualTypeHasPattern) { + const rootPatternParent = findAncestor(contextualType.pattern!.parent, n => + n.kind === SyntaxKind.VariableDeclaration || + n.kind === SyntaxKind.BinaryExpression || + n.kind === SyntaxKind.Parameter); + const spreadOrOutsideRootObject = findAncestor(node, n => + n === rootPatternParent || + n.kind === SyntaxKind.SpreadAssignment)!; + + if (spreadOrOutsideRootObject.kind !== SyntaxKind.SpreadAssignment) { + for (const prop of getPropertiesOfType(contextualType)) { + if (!propertiesTable.get(prop.escapedName) && !getPropertyOfType(spread, prop.escapedName)) { + if (!(prop.flags & SymbolFlags.Optional)) { + error(prop.valueDeclaration || tryCast(prop, isTransientSymbol)?.links.bindingElement, Diagnostics.Initializer_provides_no_value_for_this_binding_element_and_the_binding_element_has_no_default_value); + } + propertiesTable.set(prop.escapedName, prop); + propertiesArray.push(prop); + } + } + } + } + + if (isErrorType(spread)) { + return errorType; + } + + if (spread !== emptyObjectType) { + if (propertiesArray.length > 0) { + spread = getSpreadType(spread, createObjectLiteralType(), node.symbol, objectFlags, inConstContext); + propertiesArray = []; + propertiesTable = createSymbolTable(); + hasComputedStringProperty = false; + hasComputedNumberProperty = false; + } + // remap the raw emptyObjectType fed in at the top into a fresh empty object literal type, unique to this use site + return mapType(spread, t => t === emptyObjectType ? createObjectLiteralType() : t); + } + + return createObjectLiteralType(); + + function createObjectLiteralType() { + const indexInfos = []; + if (hasComputedStringProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, stringType)); + if (hasComputedNumberProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, numberType)); + if (hasComputedSymbolProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, esSymbolType)); + const result = createAnonymousType(node.symbol, propertiesTable, emptyArray, emptyArray, indexInfos); + result.objectFlags |= objectFlags | ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + if (isJSObjectLiteral) { + result.objectFlags |= ObjectFlags.JSLiteral; + } + if (patternWithComputedProperties) { + result.objectFlags |= ObjectFlags.ObjectLiteralPatternWithComputedProperties; + } + if (inDestructuringPattern) { + result.pattern = node; + } + return result; + } + } + + function isValidSpreadType(type: Type): boolean { + const t = removeDefinitelyFalsyTypes(mapType(type, getBaseConstraintOrType)); + return !!(t.flags & (TypeFlags.Any | TypeFlags.NonPrimitive | TypeFlags.Object | TypeFlags.InstantiableNonPrimitive) || + t.flags & TypeFlags.UnionOrIntersection && every((t as UnionOrIntersectionType).types, isValidSpreadType)); + } + + function checkJsxSelfClosingElementDeferred(node: JsxSelfClosingElement) { + checkJsxOpeningLikeElementOrOpeningFragment(node); + } + + function checkJsxSelfClosingElement(node: JsxSelfClosingElement, _checkMode: CheckMode | undefined): Type { + checkNodeDeferred(node); + return getJsxElementTypeAt(node) || anyType; + } + + function checkJsxElementDeferred(node: JsxElement) { + // Check attributes + checkJsxOpeningLikeElementOrOpeningFragment(node.openingElement); + + // Perform resolution on the closing tag so that rename/go to definition/etc work + if (isJsxIntrinsicTagName(node.closingElement.tagName)) { + getIntrinsicTagSymbol(node.closingElement); + } + else { + checkExpression(node.closingElement.tagName); + } + + checkJsxChildren(node); + } + + function checkJsxElement(node: JsxElement, _checkMode: CheckMode | undefined): Type { + checkNodeDeferred(node); + + return getJsxElementTypeAt(node) || anyType; + } + + function checkJsxFragment(node: JsxFragment): Type { + checkJsxOpeningLikeElementOrOpeningFragment(node.openingFragment); + + // by default, jsx:'react' will use jsxFactory = React.createElement and jsxFragmentFactory = React.Fragment + // if jsxFactory compiler option is provided, ensure jsxFragmentFactory compiler option or @jsxFrag pragma is provided too + const nodeSourceFile = getSourceFileOfNode(node); + if ( + getJSXTransformEnabled(compilerOptions) && (compilerOptions.jsxFactory || nodeSourceFile.pragmas.has("jsx")) + && !compilerOptions.jsxFragmentFactory && !nodeSourceFile.pragmas.has("jsxfrag") + ) { + error( + node, + compilerOptions.jsxFactory + ? Diagnostics.The_jsxFragmentFactory_compiler_option_must_be_provided_to_use_JSX_fragments_with_the_jsxFactory_compiler_option + : Diagnostics.An_jsxFrag_pragma_is_required_when_using_an_jsx_pragma_with_JSX_fragments, + ); + } + + checkJsxChildren(node); + return getJsxElementTypeAt(node) || anyType; + } + + function isHyphenatedJsxName(name: string | __String) { + return (name as string).includes("-"); + } + + /** + * Returns true iff React would emit this tag name as a string rather than an identifier or qualified name + */ + function isJsxIntrinsicTagName(tagName: Node): tagName is Identifier | JsxNamespacedName { + return isIdentifier(tagName) && isIntrinsicJsxName(tagName.escapedText) || isJsxNamespacedName(tagName); + } + + function checkJsxAttribute(node: JsxAttribute, checkMode?: CheckMode) { + return node.initializer + ? checkExpressionForMutableLocation(node.initializer, checkMode) + : trueType; // is sugar for + } + + /** + * Get attributes type of the JSX opening-like element. The result is from resolving "attributes" property of the opening-like element. + * + * @param openingLikeElement a JSX opening-like element + * @param filter a function to remove attributes that will not participate in checking whether attributes are assignable + * @return an anonymous type (similar to the one returned by checkObjectLiteral) in which its properties are attributes property. + * @remarks Because this function calls getSpreadType, it needs to use the same checks as checkObjectLiteral, + * which also calls getSpreadType. + */ + function createJsxAttributesTypeFromAttributesProperty(openingLikeElement: JsxOpeningLikeElement, checkMode: CheckMode = CheckMode.Normal) { + const attributes = openingLikeElement.attributes; + const contextualType = getContextualType(attributes, ContextFlags.None); + const allAttributesTable = strictNullChecks ? createSymbolTable() : undefined; + let attributesTable = createSymbolTable(); + let spread: Type = emptyJsxObjectType; + let hasSpreadAnyType = false; + let typeToIntersect: Type | undefined; + let explicitlySpecifyChildrenAttribute = false; + let objectFlags: ObjectFlags = ObjectFlags.JsxAttributes; + const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(openingLikeElement)); + + for (const attributeDecl of attributes.properties) { + const member = attributeDecl.symbol; + if (isJsxAttribute(attributeDecl)) { + const exprType = checkJsxAttribute(attributeDecl, checkMode); + objectFlags |= getObjectFlags(exprType) & ObjectFlags.PropagatingFlags; + + const attributeSymbol = createSymbol(SymbolFlags.Property | member.flags, member.escapedName); + attributeSymbol.declarations = member.declarations; + attributeSymbol.parent = member.parent; + if (member.valueDeclaration) { + attributeSymbol.valueDeclaration = member.valueDeclaration; + } + attributeSymbol.links.type = exprType; + attributeSymbol.links.target = member; + attributesTable.set(attributeSymbol.escapedName, attributeSymbol); + allAttributesTable?.set(attributeSymbol.escapedName, attributeSymbol); + if (getEscapedTextOfJsxAttributeName(attributeDecl.name) === jsxChildrenPropertyName) { + explicitlySpecifyChildrenAttribute = true; + } + if (contextualType) { + const prop = getPropertyOfType(contextualType, member.escapedName); + if (prop && prop.declarations && isDeprecatedSymbol(prop) && isIdentifier(attributeDecl.name)) { + addDeprecatedSuggestion(attributeDecl.name, prop.declarations, attributeDecl.name.escapedText as string); + } + } + if (contextualType && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && isContextSensitive(attributeDecl)) { + const inferenceContext = getInferenceContext(attributes); + Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context + const inferenceNode = (attributeDecl.initializer as JsxExpression).expression!; + addIntraExpressionInferenceSite(inferenceContext, inferenceNode, exprType); + } + } + else { + Debug.assert(attributeDecl.kind === SyntaxKind.JsxSpreadAttribute); + if (attributesTable.size > 0) { + spread = getSpreadType(spread, createJsxAttributesType(), attributes.symbol, objectFlags, /*readonly*/ false); + attributesTable = createSymbolTable(); + } + const exprType = getReducedType(checkExpression(attributeDecl.expression, checkMode & CheckMode.Inferential)); + if (isTypeAny(exprType)) { + hasSpreadAnyType = true; + } + if (isValidSpreadType(exprType)) { + spread = getSpreadType(spread, exprType, attributes.symbol, objectFlags, /*readonly*/ false); + if (allAttributesTable) { + checkSpreadPropOverrides(exprType, allAttributesTable, attributeDecl); + } + } + else { + error(attributeDecl.expression, Diagnostics.Spread_types_may_only_be_created_from_object_types); + typeToIntersect = typeToIntersect ? getIntersectionType([typeToIntersect, exprType]) : exprType; + } + } + } + + if (!hasSpreadAnyType) { + if (attributesTable.size > 0) { + spread = getSpreadType(spread, createJsxAttributesType(), attributes.symbol, objectFlags, /*readonly*/ false); + } + } + + // Handle children attribute + const parent = openingLikeElement.parent.kind === SyntaxKind.JsxElement ? openingLikeElement.parent as JsxElement : undefined; + // We have to check that openingElement of the parent is the one we are visiting as this may not be true for selfClosingElement + if (parent && parent.openingElement === openingLikeElement && getSemanticJsxChildren(parent.children).length > 0) { + const childrenTypes: Type[] = checkJsxChildren(parent, checkMode); + + if (!hasSpreadAnyType && jsxChildrenPropertyName && jsxChildrenPropertyName !== "") { + // Error if there is a attribute named "children" explicitly specified and children element. + // This is because children element will overwrite the value from attributes. + // Note: we will not warn "children" attribute overwritten if "children" attribute is specified in object spread. + if (explicitlySpecifyChildrenAttribute) { + error(attributes, Diagnostics._0_are_specified_twice_The_attribute_named_0_will_be_overwritten, unescapeLeadingUnderscores(jsxChildrenPropertyName)); + } + + const contextualType = getApparentTypeOfContextualType(openingLikeElement.attributes, /*contextFlags*/ undefined); + const childrenContextualType = contextualType && getTypeOfPropertyOfContextualType(contextualType, jsxChildrenPropertyName); + // If there are children in the body of JSX element, create dummy attribute "children" with the union of children types so that it will pass the attribute checking process + const childrenPropSymbol = createSymbol(SymbolFlags.Property, jsxChildrenPropertyName); + childrenPropSymbol.links.type = childrenTypes.length === 1 ? childrenTypes[0] : + childrenContextualType && someType(childrenContextualType, isTupleLikeType) ? createTupleType(childrenTypes) : + createArrayType(getUnionType(childrenTypes)); + // Fake up a property declaration for the children + childrenPropSymbol.valueDeclaration = factory.createPropertySignature(/*modifiers*/ undefined, unescapeLeadingUnderscores(jsxChildrenPropertyName), /*questionToken*/ undefined, /*type*/ undefined); + setParent(childrenPropSymbol.valueDeclaration, attributes); + childrenPropSymbol.valueDeclaration.symbol = childrenPropSymbol; + const childPropMap = createSymbolTable(); + childPropMap.set(jsxChildrenPropertyName, childrenPropSymbol); + spread = getSpreadType(spread, createAnonymousType(attributes.symbol, childPropMap, emptyArray, emptyArray, emptyArray), attributes.symbol, objectFlags, /*readonly*/ false); + } + } + + if (hasSpreadAnyType) { + return anyType; + } + if (typeToIntersect && spread !== emptyJsxObjectType) { + return getIntersectionType([typeToIntersect, spread]); + } + return typeToIntersect || (spread === emptyJsxObjectType ? createJsxAttributesType() : spread); + + /** + * Create anonymous type from given attributes symbol table. + * @param symbol a symbol of JsxAttributes containing attributes corresponding to attributesTable + * @param attributesTable a symbol table of attributes property + */ + function createJsxAttributesType() { + objectFlags |= ObjectFlags.FreshLiteral; + const result = createAnonymousType(attributes.symbol, attributesTable, emptyArray, emptyArray, emptyArray); + result.objectFlags |= objectFlags | ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + return result; + } + } + + function checkJsxChildren(node: JsxElement | JsxFragment, checkMode?: CheckMode) { + const childrenTypes: Type[] = []; + for (const child of node.children) { + // In React, JSX text that contains only whitespaces will be ignored so we don't want to type-check that + // because then type of children property will have constituent of string type. + if (child.kind === SyntaxKind.JsxText) { + if (!child.containsOnlyTriviaWhiteSpaces) { + childrenTypes.push(stringType); + } + } + else if (child.kind === SyntaxKind.JsxExpression && !child.expression) { + continue; // empty jsx expressions don't *really* count as present children + } + else { + childrenTypes.push(checkExpressionForMutableLocation(child, checkMode)); + } + } + return childrenTypes; + } + + function checkSpreadPropOverrides(type: Type, props: SymbolTable, spread: SpreadAssignment | JsxSpreadAttribute) { + for (const right of getPropertiesOfType(type)) { + if (!(right.flags & SymbolFlags.Optional)) { + const left = props.get(right.escapedName); + if (left) { + const diagnostic = error(left.valueDeclaration, Diagnostics._0_is_specified_more_than_once_so_this_usage_will_be_overwritten, unescapeLeadingUnderscores(left.escapedName)); + addRelatedInfo(diagnostic, createDiagnosticForNode(spread, Diagnostics.This_spread_always_overwrites_this_property)); + } + } + } + } + + /** + * Check attributes property of opening-like element. This function is called during chooseOverload to get call signature of a JSX opening-like element. + * (See "checkApplicableSignatureForJsxOpeningLikeElement" for how the function is used) + * @param node a JSXAttributes to be resolved of its type + */ + function checkJsxAttributes(node: JsxAttributes, checkMode: CheckMode | undefined) { + return createJsxAttributesTypeFromAttributesProperty(node.parent, checkMode); + } + + function getJsxType(name: __String, location: Node | undefined) { + const namespace = getJsxNamespaceAt(location); + const exports = namespace && getExportsOfSymbol(namespace); + const typeSymbol = exports && getSymbol(exports, name, SymbolFlags.Type); + return typeSymbol ? getDeclaredTypeOfSymbol(typeSymbol) : errorType; + } + + /** + * Looks up an intrinsic tag name and returns a symbol that either points to an intrinsic + * property (in which case nodeLinks.jsxFlags will be IntrinsicNamedElement) or an intrinsic + * string index signature (in which case nodeLinks.jsxFlags will be IntrinsicIndexedElement). + * May also return unknownSymbol if both of these lookups fail. + */ + function getIntrinsicTagSymbol(node: JsxOpeningLikeElement | JsxClosingElement): Symbol { + const links = getNodeLinks(node); + if (!links.resolvedSymbol) { + const intrinsicElementsType = getJsxType(JsxNames.IntrinsicElements, node); + if (!isErrorType(intrinsicElementsType)) { + // Property case + if (!isIdentifier(node.tagName) && !isJsxNamespacedName(node.tagName)) return Debug.fail(); + const propName = isJsxNamespacedName(node.tagName) ? getEscapedTextOfJsxNamespacedName(node.tagName) : node.tagName.escapedText; + const intrinsicProp = getPropertyOfType(intrinsicElementsType, propName); + if (intrinsicProp) { + links.jsxFlags |= JsxFlags.IntrinsicNamedElement; + return links.resolvedSymbol = intrinsicProp; + } + + // Intrinsic string indexer case + const indexSymbol = getApplicableIndexSymbol(intrinsicElementsType, getStringLiteralType(unescapeLeadingUnderscores(propName))); + if (indexSymbol) { + links.jsxFlags |= JsxFlags.IntrinsicIndexedElement; + return links.resolvedSymbol = indexSymbol; + } + + if (getTypeOfPropertyOrIndexSignatureOfType(intrinsicElementsType, propName)) { + links.jsxFlags |= JsxFlags.IntrinsicIndexedElement; + return links.resolvedSymbol = intrinsicElementsType.symbol; + } + + // Wasn't found + error(node, Diagnostics.Property_0_does_not_exist_on_type_1, intrinsicTagNameToString(node.tagName), "JSX." + JsxNames.IntrinsicElements); + return links.resolvedSymbol = unknownSymbol; + } + else { + if (noImplicitAny) { + error(node, Diagnostics.JSX_element_implicitly_has_type_any_because_no_interface_JSX_0_exists, unescapeLeadingUnderscores(JsxNames.IntrinsicElements)); + } + return links.resolvedSymbol = unknownSymbol; + } + } + return links.resolvedSymbol; + } + + function getJsxNamespaceContainerForImplicitImport(location: Node | undefined): Symbol | undefined { + const file = location && getSourceFileOfNode(location); + const links = file && getNodeLinks(file); + if (links && links.jsxImplicitImportContainer === false) { + return undefined; + } + if (links && links.jsxImplicitImportContainer) { + return links.jsxImplicitImportContainer; + } + const runtimeImportSpecifier = getJSXRuntimeImport(getJSXImplicitImportBase(compilerOptions, file), compilerOptions); + if (!runtimeImportSpecifier) { + return undefined; + } + const isClassic = getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic; + const errorMessage = isClassic + ? Diagnostics.Cannot_find_module_0_Did_you_mean_to_set_the_moduleResolution_option_to_nodenext_or_to_add_aliases_to_the_paths_option + : Diagnostics.Cannot_find_module_0_or_its_corresponding_type_declarations; + const specifier = getJSXRuntimeImportSpecifier(file, runtimeImportSpecifier); + const mod = resolveExternalModule(specifier || location!, runtimeImportSpecifier, errorMessage, location!); + const result = mod && mod !== unknownSymbol ? getMergedSymbol(resolveSymbol(mod)) : undefined; + if (links) { + links.jsxImplicitImportContainer = result || false; + } + return result; + } + + function getJsxNamespaceAt(location: Node | undefined): Symbol { + const links = location && getNodeLinks(location); + if (links && links.jsxNamespace) { + return links.jsxNamespace; + } + if (!links || links.jsxNamespace !== false) { + let resolvedNamespace = getJsxNamespaceContainerForImplicitImport(location); + + if (!resolvedNamespace || resolvedNamespace === unknownSymbol) { + const namespaceName = getJsxNamespace(location); + resolvedNamespace = resolveName(location, namespaceName, SymbolFlags.Namespace, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + } + + if (resolvedNamespace) { + const candidate = resolveSymbol(getSymbol(getExportsOfSymbol(resolveSymbol(resolvedNamespace)), JsxNames.JSX, SymbolFlags.Namespace)); + if (candidate && candidate !== unknownSymbol) { + if (links) { + links.jsxNamespace = candidate; + } + return candidate; + } + } + if (links) { + links.jsxNamespace = false; + } + } + // JSX global fallback + const s = resolveSymbol(getGlobalSymbol(JsxNames.JSX, SymbolFlags.Namespace, /*diagnostic*/ undefined)); + if (s === unknownSymbol) { + return undefined!; // TODO: GH#18217 + } + return s!; // TODO: GH#18217 + } + + /** + * Look into JSX namespace and then look for container with matching name as nameOfAttribPropContainer. + * Get a single property from that container if existed. Report an error if there are more than one property. + * + * @param nameOfAttribPropContainer a string of value JsxNames.ElementAttributesPropertyNameContainer or JsxNames.ElementChildrenAttributeNameContainer + * if other string is given or the container doesn't exist, return undefined. + */ + function getNameFromJsxElementAttributesContainer(nameOfAttribPropContainer: __String, jsxNamespace: Symbol): __String | undefined { + // JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute [symbol] + const jsxElementAttribPropInterfaceSym = jsxNamespace && getSymbol(jsxNamespace.exports!, nameOfAttribPropContainer, SymbolFlags.Type); + // JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute [type] + const jsxElementAttribPropInterfaceType = jsxElementAttribPropInterfaceSym && getDeclaredTypeOfSymbol(jsxElementAttribPropInterfaceSym); + // The properties of JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute + const propertiesOfJsxElementAttribPropInterface = jsxElementAttribPropInterfaceType && getPropertiesOfType(jsxElementAttribPropInterfaceType); + if (propertiesOfJsxElementAttribPropInterface) { + // Element Attributes has zero properties, so the element attributes type will be the class instance type + if (propertiesOfJsxElementAttribPropInterface.length === 0) { + return "" as __String; + } + // Element Attributes has one property, so the element attributes type will be the type of the corresponding + // property of the class instance type + else if (propertiesOfJsxElementAttribPropInterface.length === 1) { + return propertiesOfJsxElementAttribPropInterface[0].escapedName; + } + else if (propertiesOfJsxElementAttribPropInterface.length > 1 && jsxElementAttribPropInterfaceSym.declarations) { + // More than one property on ElementAttributesProperty is an error + error(jsxElementAttribPropInterfaceSym.declarations[0], Diagnostics.The_global_type_JSX_0_may_not_have_more_than_one_property, unescapeLeadingUnderscores(nameOfAttribPropContainer)); + } + } + return undefined; + } + + function getJsxLibraryManagedAttributes(jsxNamespace: Symbol) { + // JSX.LibraryManagedAttributes [symbol] + return jsxNamespace && getSymbol(jsxNamespace.exports!, JsxNames.LibraryManagedAttributes, SymbolFlags.Type); + } + + function getJsxElementTypeSymbol(jsxNamespace: Symbol) { + // JSX.ElementType [symbol] + return jsxNamespace && getSymbol(jsxNamespace.exports!, JsxNames.ElementType, SymbolFlags.Type); + } + + /// e.g. "props" for React.d.ts, + /// or 'undefined' if ElementAttributesProperty doesn't exist (which means all + /// non-intrinsic elements' attributes type is 'any'), + /// or '' if it has 0 properties (which means every + /// non-intrinsic elements' attributes type is the element instance type) + function getJsxElementPropertiesName(jsxNamespace: Symbol) { + return getNameFromJsxElementAttributesContainer(JsxNames.ElementAttributesPropertyNameContainer, jsxNamespace); + } + + function getJsxElementChildrenPropertyName(jsxNamespace: Symbol): __String | undefined { + return getNameFromJsxElementAttributesContainer(JsxNames.ElementChildrenAttributeNameContainer, jsxNamespace); + } + + function getUninstantiatedJsxSignaturesOfType(elementType: Type, caller: JsxOpeningLikeElement): readonly Signature[] { + if (elementType.flags & TypeFlags.String) { + return [anySignature]; + } + else if (elementType.flags & TypeFlags.StringLiteral) { + const intrinsicType = getIntrinsicAttributesTypeFromStringLiteralType(elementType as StringLiteralType, caller); + if (!intrinsicType) { + error(caller, Diagnostics.Property_0_does_not_exist_on_type_1, (elementType as StringLiteralType).value, "JSX." + JsxNames.IntrinsicElements); + return emptyArray; + } + else { + const fakeSignature = createSignatureForJSXIntrinsic(caller, intrinsicType); + return [fakeSignature]; + } + } + const apparentElemType = getApparentType(elementType); + // Resolve the signatures, preferring constructor + let signatures = getSignaturesOfType(apparentElemType, SignatureKind.Construct); + if (signatures.length === 0) { + // No construct signatures, try call signatures + signatures = getSignaturesOfType(apparentElemType, SignatureKind.Call); + } + if (signatures.length === 0 && apparentElemType.flags & TypeFlags.Union) { + // If each member has some combination of new/call signatures; make a union signature list for those + signatures = getUnionSignatures(map((apparentElemType as UnionType).types, t => getUninstantiatedJsxSignaturesOfType(t, caller))); + } + return signatures; + } + + function getIntrinsicAttributesTypeFromStringLiteralType(type: StringLiteralType, location: Node): Type | undefined { + // If the elemType is a stringLiteral type, we can then provide a check to make sure that the string literal type is one of the Jsx intrinsic element type + // For example: + // var CustomTag: "h1" = "h1"; + // Hello World + const intrinsicElementsType = getJsxType(JsxNames.IntrinsicElements, location); + if (!isErrorType(intrinsicElementsType)) { + const stringLiteralTypeName = type.value; + const intrinsicProp = getPropertyOfType(intrinsicElementsType, escapeLeadingUnderscores(stringLiteralTypeName)); + if (intrinsicProp) { + return getTypeOfSymbol(intrinsicProp); + } + const indexSignatureType = getIndexTypeOfType(intrinsicElementsType, stringType); + if (indexSignatureType) { + return indexSignatureType; + } + return undefined; + } + // If we need to report an error, we already done so here. So just return any to prevent any more error downstream + return anyType; + } + + function checkJsxReturnAssignableToAppropriateBound(refKind: JsxReferenceKind, elemInstanceType: Type, openingLikeElement: JsxOpeningLikeElement) { + if (refKind === JsxReferenceKind.Function) { + const sfcReturnConstraint = getJsxStatelessElementTypeAt(openingLikeElement); + if (sfcReturnConstraint) { + checkTypeRelatedTo(elemInstanceType, sfcReturnConstraint, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_return_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); + } + } + else if (refKind === JsxReferenceKind.Component) { + const classConstraint = getJsxElementClassTypeAt(openingLikeElement); + if (classConstraint) { + // Issue an error if this return type isn't assignable to JSX.ElementClass, failing that + checkTypeRelatedTo(elemInstanceType, classConstraint, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_instance_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); + } + } + else { // Mixed + const sfcReturnConstraint = getJsxStatelessElementTypeAt(openingLikeElement); + const classConstraint = getJsxElementClassTypeAt(openingLikeElement); + if (!sfcReturnConstraint || !classConstraint) { + return; + } + const combined = getUnionType([sfcReturnConstraint, classConstraint]); + checkTypeRelatedTo(elemInstanceType, combined, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_element_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); + } + + function generateInitialErrorChain(): DiagnosticMessageChain { + const componentName = getTextOfNode(openingLikeElement.tagName); + return chainDiagnosticMessages(/*details*/ undefined, Diagnostics._0_cannot_be_used_as_a_JSX_component, componentName); + } + } + + /** + * Get attributes type of the given intrinsic opening-like Jsx element by resolving the tag name. + * The function is intended to be called from a function which has checked that the opening element is an intrinsic element. + * @param node an intrinsic JSX opening-like element + */ + function getIntrinsicAttributesTypeFromJsxOpeningLikeElement(node: JsxOpeningLikeElement): Type { + Debug.assert(isJsxIntrinsicTagName(node.tagName)); + const links = getNodeLinks(node); + if (!links.resolvedJsxElementAttributesType) { + const symbol = getIntrinsicTagSymbol(node); + if (links.jsxFlags & JsxFlags.IntrinsicNamedElement) { + return links.resolvedJsxElementAttributesType = getTypeOfSymbol(symbol) || errorType; + } + else if (links.jsxFlags & JsxFlags.IntrinsicIndexedElement) { + const propName = isJsxNamespacedName(node.tagName) ? getEscapedTextOfJsxNamespacedName(node.tagName) : node.tagName.escapedText; + return links.resolvedJsxElementAttributesType = getApplicableIndexInfoForName(getJsxType(JsxNames.IntrinsicElements, node), propName)?.type || errorType; + } + else { + return links.resolvedJsxElementAttributesType = errorType; + } + } + return links.resolvedJsxElementAttributesType; + } + + function getJsxElementClassTypeAt(location: Node): Type | undefined { + const type = getJsxType(JsxNames.ElementClass, location); + if (isErrorType(type)) return undefined; + return type; + } + + function getJsxElementTypeAt(location: Node): Type { + return getJsxType(JsxNames.Element, location); + } + + function getJsxStatelessElementTypeAt(location: Node): Type | undefined { + const jsxElementType = getJsxElementTypeAt(location); + if (jsxElementType) { + return getUnionType([jsxElementType, nullType]); + } + } + + function getJsxElementTypeTypeAt(location: Node): Type | undefined { + const ns = getJsxNamespaceAt(location); + if (!ns) return undefined; + const sym = getJsxElementTypeSymbol(ns); + if (!sym) return undefined; + const type = instantiateAliasOrInterfaceWithDefaults(sym, isInJSFile(location)); + if (!type || isErrorType(type)) return undefined; + return type; + } + + function instantiateAliasOrInterfaceWithDefaults(managedSym: Symbol, inJs: boolean, ...typeArguments: Type[]) { + const declaredManagedType = getDeclaredTypeOfSymbol(managedSym); // fetches interface type, or initializes symbol links type parmaeters + if (managedSym.flags & SymbolFlags.TypeAlias) { + const params = getSymbolLinks(managedSym).typeParameters; + if (length(params) >= typeArguments.length) { + const args = fillMissingTypeArguments(typeArguments, params, typeArguments.length, inJs); + return length(args) === 0 ? declaredManagedType : getTypeAliasInstantiation(managedSym, args); + } + } + if (length((declaredManagedType as GenericType).typeParameters) >= typeArguments.length) { + const args = fillMissingTypeArguments(typeArguments, (declaredManagedType as GenericType).typeParameters, typeArguments.length, inJs); + return createTypeReference(declaredManagedType as GenericType, args); + } + return undefined; + } + + /** + * Returns all the properties of the Jsx.IntrinsicElements interface + */ + function getJsxIntrinsicTagNamesAt(location: Node): Symbol[] { + const intrinsics = getJsxType(JsxNames.IntrinsicElements, location); + return intrinsics ? getPropertiesOfType(intrinsics) : emptyArray; + } + + function checkJsxPreconditions(errorNode: Node) { + // Preconditions for using JSX + if ((compilerOptions.jsx || JsxEmit.None) === JsxEmit.None) { + error(errorNode, Diagnostics.Cannot_use_JSX_unless_the_jsx_flag_is_provided); + } + + if (getJsxElementTypeAt(errorNode) === undefined) { + if (noImplicitAny) { + error(errorNode, Diagnostics.JSX_element_implicitly_has_type_any_because_the_global_type_JSX_Element_does_not_exist); + } + } + } + + function checkJsxOpeningLikeElementOrOpeningFragment(node: JsxOpeningLikeElement | JsxOpeningFragment) { + const isNodeOpeningLikeElement = isJsxOpeningLikeElement(node); + + if (isNodeOpeningLikeElement) { + checkGrammarJsxElement(node); + } + + checkJsxPreconditions(node); + + markLinkedReferences(node, ReferenceHint.Jsx); + + if (isNodeOpeningLikeElement) { + const jsxOpeningLikeNode = node; + const sig = getResolvedSignature(jsxOpeningLikeNode); + checkDeprecatedSignature(sig, node); + + const elementTypeConstraint = getJsxElementTypeTypeAt(jsxOpeningLikeNode); + if (elementTypeConstraint !== undefined) { + const tagName = jsxOpeningLikeNode.tagName; + const tagType = isJsxIntrinsicTagName(tagName) + ? getStringLiteralType(intrinsicTagNameToString(tagName)) + : checkExpression(tagName); + checkTypeRelatedTo(tagType, elementTypeConstraint, assignableRelation, tagName, Diagnostics.Its_type_0_is_not_a_valid_JSX_element_type, () => { + const componentName = getTextOfNode(tagName); + return chainDiagnosticMessages(/*details*/ undefined, Diagnostics._0_cannot_be_used_as_a_JSX_component, componentName); + }); + } + else { + checkJsxReturnAssignableToAppropriateBound(getJsxReferenceKind(jsxOpeningLikeNode), getReturnTypeOfSignature(sig), jsxOpeningLikeNode); + } + } + } + + /** + * Check if a property with the given name is known anywhere in the given type. In an object type, a property + * is considered known if + * 1. the object type is empty and the check is for assignability, or + * 2. if the object type has index signatures, or + * 3. if the property is actually declared in the object type + * (this means that 'toString', for example, is not usually a known property). + * 4. In a union or intersection type, + * a property is considered known if it is known in any constituent type. + * @param targetType a type to search a given name in + * @param name a property name to search + * @param isComparingJsxAttributes a boolean flag indicating whether we are searching in JsxAttributesType + */ + function isKnownProperty(targetType: Type, name: __String, isComparingJsxAttributes: boolean): boolean { + if (targetType.flags & TypeFlags.Object) { + // For backwards compatibility a symbol-named property is satisfied by a string index signature. This + // is incorrect and inconsistent with element access expressions, where it is an error, so eventually + // we should remove this exception. + if ( + getPropertyOfObjectType(targetType, name) || + getApplicableIndexInfoForName(targetType, name) || + isLateBoundName(name) && getIndexInfoOfType(targetType, stringType) || + isComparingJsxAttributes && isHyphenatedJsxName(name) + ) { + // For JSXAttributes, if the attribute has a hyphenated name, consider that the attribute to be known. + return true; + } + } + if (targetType.flags & TypeFlags.Substitution) { + return isKnownProperty((targetType as SubstitutionType).baseType, name, isComparingJsxAttributes); + } + if (targetType.flags & TypeFlags.UnionOrIntersection && isExcessPropertyCheckTarget(targetType)) { + for (const t of (targetType as UnionOrIntersectionType).types) { + if (isKnownProperty(t, name, isComparingJsxAttributes)) { + return true; + } + } + } + return false; + } + + function isExcessPropertyCheckTarget(type: Type): boolean { + return !!(type.flags & TypeFlags.Object && !(getObjectFlags(type) & ObjectFlags.ObjectLiteralPatternWithComputedProperties) || + type.flags & TypeFlags.NonPrimitive || + type.flags & TypeFlags.Substitution && isExcessPropertyCheckTarget((type as SubstitutionType).baseType) || + type.flags & TypeFlags.Union && some((type as UnionType).types, isExcessPropertyCheckTarget) || + type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, isExcessPropertyCheckTarget)); + } + + function checkJsxExpression(node: JsxExpression, checkMode?: CheckMode) { + checkGrammarJsxExpression(node); + if (node.expression) { + const type = checkExpression(node.expression, checkMode); + if (node.dotDotDotToken && type !== anyType && !isArrayType(type)) { + error(node, Diagnostics.JSX_spread_child_must_be_an_array_type); + } + return type; + } + else { + return errorType; + } + } + + function getDeclarationNodeFlagsFromSymbol(s: Symbol): NodeFlags { + return s.valueDeclaration ? getCombinedNodeFlagsCached(s.valueDeclaration) : 0; + } + + /** + * Return whether this symbol is a member of a prototype somewhere + * Note that this is not tracked well within the compiler, so the answer may be incorrect. + */ + function isPrototypeProperty(symbol: Symbol) { + if (symbol.flags & SymbolFlags.Method || getCheckFlags(symbol) & CheckFlags.SyntheticMethod) { + return true; + } + if (isInJSFile(symbol.valueDeclaration)) { + const parent = symbol.valueDeclaration!.parent; + return parent && isBinaryExpression(parent) && + getAssignmentDeclarationKind(parent) === AssignmentDeclarationKind.PrototypeProperty; + } + } + + /** + * Check whether the requested property access is valid. + * Returns true if node is a valid property access, and false otherwise. + * @param node The node to be checked. + * @param isSuper True if the access is from `super.`. + * @param type The type of the object whose property is being accessed. (Not the type of the property.) + * @param prop The symbol for the property being accessed. + */ + function checkPropertyAccessibility( + node: PropertyAccessExpression | QualifiedName | PropertyAccessExpression | VariableDeclaration | ParameterDeclaration | ImportTypeNode | PropertyAssignment | ShorthandPropertyAssignment | BindingElement, + isSuper: boolean, + writing: boolean, + type: Type, + prop: Symbol, + reportError = true, + ): boolean { + const errorNode = !reportError ? undefined : + node.kind === SyntaxKind.QualifiedName ? node.right : + node.kind === SyntaxKind.ImportType ? node : + node.kind === SyntaxKind.BindingElement && node.propertyName ? node.propertyName : node.name; + + return checkPropertyAccessibilityAtLocation(node, isSuper, writing, type, prop, errorNode); + } + + /** + * Check whether the requested property can be accessed at the requested location. + * Returns true if node is a valid property access, and false otherwise. + * @param location The location node where we want to check if the property is accessible. + * @param isSuper True if the access is from `super.`. + * @param writing True if this is a write property access, false if it is a read property access. + * @param containingType The type of the object whose property is being accessed. (Not the type of the property.) + * @param prop The symbol for the property being accessed. + * @param errorNode The node where we should report an invalid property access error, or undefined if we should not report errors. + */ + function checkPropertyAccessibilityAtLocation(location: Node, isSuper: boolean, writing: boolean, containingType: Type, prop: Symbol, errorNode?: Node): boolean { + const flags = getDeclarationModifierFlagsFromSymbol(prop, writing); + + if (isSuper) { + // TS 1.0 spec (April 2014): 4.8.2 + // - In a constructor, instance member function, instance member accessor, or + // instance member variable initializer where this references a derived class instance, + // a super property access is permitted and must specify a public instance member function of the base class. + // - In a static member function or static member accessor + // where this references the constructor function object of a derived class, + // a super property access is permitted and must specify a public static member function of the base class. + if (languageVersion < ScriptTarget.ES2015) { + if (symbolHasNonMethodDeclaration(prop)) { + if (errorNode) { + error(errorNode, Diagnostics.Only_public_and_protected_methods_of_the_base_class_are_accessible_via_the_super_keyword); + } + return false; + } + } + if (flags & ModifierFlags.Abstract) { + // A method cannot be accessed in a super property access if the method is abstract. + // This error could mask a private property access error. But, a member + // cannot simultaneously be private and abstract, so this will trigger an + // additional error elsewhere. + if (errorNode) { + error(errorNode, Diagnostics.Abstract_method_0_in_class_1_cannot_be_accessed_via_super_expression, symbolToString(prop), typeToString(getDeclaringClass(prop)!)); + } + return false; + } + // A class field cannot be accessed via super.* from a derived class. + // This is true for both [[Set]] (old) and [[Define]] (ES spec) semantics. + if (!(flags & ModifierFlags.Static) && prop.declarations?.some(isClassInstanceProperty)) { + if (errorNode) { + error(errorNode, Diagnostics.Class_field_0_defined_by_the_parent_class_is_not_accessible_in_the_child_class_via_super, symbolToString(prop)); + } + return false; + } + } + + // Referencing abstract properties within their own constructors is not allowed + if ( + (flags & ModifierFlags.Abstract) && symbolHasNonMethodDeclaration(prop) && + (isThisProperty(location) || isThisInitializedObjectBindingExpression(location) || isObjectBindingPattern(location.parent) && isThisInitializedDeclaration(location.parent.parent)) + ) { + const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(getParentOfSymbol(prop)!); + if (declaringClassDeclaration && isNodeUsedDuringClassInitialization(location)) { + if (errorNode) { + error(errorNode, Diagnostics.Abstract_property_0_in_class_1_cannot_be_accessed_in_the_constructor, symbolToString(prop), getTextOfIdentifierOrLiteral(declaringClassDeclaration.name!)); + } + return false; + } + } + + // Public properties are otherwise accessible. + if (!(flags & ModifierFlags.NonPublicAccessibilityModifier)) { + return true; + } + + // Property is known to be private or protected at this point + + // Private property is accessible if the property is within the declaring class + if (flags & ModifierFlags.Private) { + const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(getParentOfSymbol(prop)!)!; + if (!isNodeWithinClass(location, declaringClassDeclaration)) { + if (errorNode) { + error(errorNode, Diagnostics.Property_0_is_private_and_only_accessible_within_class_1, symbolToString(prop), typeToString(getDeclaringClass(prop)!)); + } + return false; + } + return true; + } + + // Property is known to be protected at this point + + // All protected properties of a supertype are accessible in a super access + if (isSuper) { + return true; + } + + // Find the first enclosing class that has the declaring classes of the protected constituents + // of the property as base classes + let enclosingClass = forEachEnclosingClass(location, enclosingDeclaration => { + const enclosingClass = getDeclaredTypeOfSymbol(getSymbolOfDeclaration(enclosingDeclaration)) as InterfaceType; + return isClassDerivedFromDeclaringClasses(enclosingClass, prop, writing); + }); + // A protected property is accessible if the property is within the declaring class or classes derived from it + if (!enclosingClass) { + // allow PropertyAccessibility if context is in function with this parameter + // static member access is disallowed + enclosingClass = getEnclosingClassFromThisParameter(location); + enclosingClass = enclosingClass && isClassDerivedFromDeclaringClasses(enclosingClass, prop, writing); + if (flags & ModifierFlags.Static || !enclosingClass) { + if (errorNode) { + error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_within_class_1_and_its_subclasses, symbolToString(prop), typeToString(getDeclaringClass(prop) || containingType)); + } + return false; + } + } + // No further restrictions for static properties + if (flags & ModifierFlags.Static) { + return true; + } + if (containingType.flags & TypeFlags.TypeParameter) { + // get the original type -- represented as the type constraint of the 'this' type + containingType = (containingType as TypeParameter).isThisType ? getConstraintOfTypeParameter(containingType as TypeParameter)! : getBaseConstraintOfType(containingType as TypeParameter)!; // TODO: GH#18217 Use a different variable that's allowed to be undefined + } + if (!containingType || !hasBaseType(containingType, enclosingClass)) { + if (errorNode) { + error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_through_an_instance_of_class_1_This_is_an_instance_of_class_2, symbolToString(prop), typeToString(enclosingClass), typeToString(containingType)); + } + return false; + } + return true; + } + + function getEnclosingClassFromThisParameter(node: Node): InterfaceType | undefined { + const thisParameter = getThisParameterFromNodeContext(node); + let thisType = thisParameter?.type && getTypeFromTypeNode(thisParameter.type); + if (thisType && thisType.flags & TypeFlags.TypeParameter) { + thisType = getConstraintOfTypeParameter(thisType as TypeParameter); + } + if (thisType && getObjectFlags(thisType) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference)) { + return getTargetType(thisType) as InterfaceType; + } + return undefined; + } + + function getThisParameterFromNodeContext(node: Node) { + const thisContainer = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + return thisContainer && isFunctionLike(thisContainer) ? getThisParameter(thisContainer) : undefined; + } + + function symbolHasNonMethodDeclaration(symbol: Symbol) { + return !!forEachProperty(symbol, prop => !(prop.flags & SymbolFlags.Method)); + } + + function checkNonNullExpression(node: Expression | QualifiedName) { + return checkNonNullType(checkExpression(node), node); + } + + function isNullableType(type: Type) { + return hasTypeFacts(type, TypeFacts.IsUndefinedOrNull); + } + + function getNonNullableTypeIfNeeded(type: Type) { + return isNullableType(type) ? getNonNullableType(type) : type; + } + + function reportObjectPossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) { + const nodeText = isEntityNameExpression(node) ? entityNameToString(node) : undefined; + if (node.kind === SyntaxKind.NullKeyword) { + error(node, Diagnostics.The_value_0_cannot_be_used_here, "null"); + return; + } + if (nodeText !== undefined && nodeText.length < 100) { + if (isIdentifier(node) && nodeText === "undefined") { + error(node, Diagnostics.The_value_0_cannot_be_used_here, "undefined"); + return; + } + error( + node, + facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? + Diagnostics._0_is_possibly_null_or_undefined : + Diagnostics._0_is_possibly_undefined : + Diagnostics._0_is_possibly_null, + nodeText, + ); + } + else { + error( + node, + facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? + Diagnostics.Object_is_possibly_null_or_undefined : + Diagnostics.Object_is_possibly_undefined : + Diagnostics.Object_is_possibly_null, + ); + } + } + + function reportCannotInvokePossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) { + error( + node, + facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? + Diagnostics.Cannot_invoke_an_object_which_is_possibly_null_or_undefined : + Diagnostics.Cannot_invoke_an_object_which_is_possibly_undefined : + Diagnostics.Cannot_invoke_an_object_which_is_possibly_null, + ); + } + + function checkNonNullTypeWithReporter( + type: Type, + node: Node, + reportError: (node: Node, facts: TypeFacts) => void, + ): Type { + if (strictNullChecks && type.flags & TypeFlags.Unknown) { + if (isEntityNameExpression(node)) { + const nodeText = entityNameToString(node); + if (nodeText.length < 100) { + error(node, Diagnostics._0_is_of_type_unknown, nodeText); + return errorType; + } + } + error(node, Diagnostics.Object_is_of_type_unknown); + return errorType; + } + const facts = getTypeFacts(type, TypeFacts.IsUndefinedOrNull); + if (facts & TypeFacts.IsUndefinedOrNull) { + reportError(node, facts); + const t = getNonNullableType(type); + return t.flags & (TypeFlags.Nullable | TypeFlags.Never) ? errorType : t; + } + return type; + } + + function checkNonNullType(type: Type, node: Node) { + return checkNonNullTypeWithReporter(type, node, reportObjectPossiblyNullOrUndefinedError); + } + + function checkNonNullNonVoidType(type: Type, node: Node): Type { + const nonNullType = checkNonNullType(type, node); + if (nonNullType.flags & TypeFlags.Void) { + if (isEntityNameExpression(node)) { + const nodeText = entityNameToString(node); + if (isIdentifier(node) && nodeText === "undefined") { + error(node, Diagnostics.The_value_0_cannot_be_used_here, nodeText); + return nonNullType; + } + if (nodeText.length < 100) { + error(node, Diagnostics._0_is_possibly_undefined, nodeText); + return nonNullType; + } + } + error(node, Diagnostics.Object_is_possibly_undefined); + } + return nonNullType; + } + + function checkPropertyAccessExpression(node: PropertyAccessExpression, checkMode: CheckMode | undefined, writeOnly?: boolean) { + return node.flags & NodeFlags.OptionalChain ? checkPropertyAccessChain(node as PropertyAccessChain, checkMode) : + checkPropertyAccessExpressionOrQualifiedName(node, node.expression, checkNonNullExpression(node.expression), node.name, checkMode, writeOnly); + } + + function checkPropertyAccessChain(node: PropertyAccessChain, checkMode: CheckMode | undefined) { + const leftType = checkExpression(node.expression); + const nonOptionalType = getOptionalExpressionType(leftType, node.expression); + return propagateOptionalTypeMarker(checkPropertyAccessExpressionOrQualifiedName(node, node.expression, checkNonNullType(nonOptionalType, node.expression), node.name, checkMode), node, nonOptionalType !== leftType); + } + + function checkQualifiedName(node: QualifiedName, checkMode: CheckMode | undefined) { + const leftType = isPartOfTypeQuery(node) && isThisIdentifier(node.left) ? checkNonNullType(checkThisExpression(node.left), node.left) : checkNonNullExpression(node.left); + return checkPropertyAccessExpressionOrQualifiedName(node, node.left, leftType, node.right, checkMode); + } + + function isMethodAccessForCall(node: Node) { + while (node.parent.kind === SyntaxKind.ParenthesizedExpression) { + node = node.parent; + } + return isCallOrNewExpression(node.parent) && node.parent.expression === node; + } + + // Lookup the private identifier lexically. + function lookupSymbolForPrivateIdentifierDeclaration(propName: __String, location: Node): Symbol | undefined { + for (let containingClass = getContainingClassExcludingClassDecorators(location); !!containingClass; containingClass = getContainingClass(containingClass)) { + const { symbol } = containingClass; + const name = getSymbolNameForPrivateIdentifier(symbol, propName); + const prop = (symbol.members && symbol.members.get(name)) || (symbol.exports && symbol.exports.get(name)); + if (prop) { + return prop; + } + } + } + + function checkGrammarPrivateIdentifierExpression(privId: PrivateIdentifier): boolean { + if (!getContainingClass(privId)) { + return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + + if (!isForInStatement(privId.parent)) { + if (!isExpressionNode(privId)) { + return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_only_allowed_in_class_bodies_and_may_only_be_used_as_part_of_a_class_member_declaration_property_access_or_on_the_left_hand_side_of_an_in_expression); + } + + const isInOperation = isBinaryExpression(privId.parent) && privId.parent.operatorToken.kind === SyntaxKind.InKeyword; + if (!getSymbolForPrivateIdentifierExpression(privId) && !isInOperation) { + return grammarErrorOnNode(privId, Diagnostics.Cannot_find_name_0, idText(privId)); + } + } + + return false; + } + + function checkPrivateIdentifierExpression(privId: PrivateIdentifier): Type { + checkGrammarPrivateIdentifierExpression(privId); + const symbol = getSymbolForPrivateIdentifierExpression(privId); + if (symbol) { + markPropertyAsReferenced(symbol, /*nodeForCheckWriteOnly*/ undefined, /*isSelfTypeAccess*/ false); + } + return anyType; + } + + function getSymbolForPrivateIdentifierExpression(privId: PrivateIdentifier): Symbol | undefined { + if (!isExpressionNode(privId)) { + return undefined; + } + + const links = getNodeLinks(privId); + if (links.resolvedSymbol === undefined) { + links.resolvedSymbol = lookupSymbolForPrivateIdentifierDeclaration(privId.escapedText, privId); + } + return links.resolvedSymbol; + } + + function getPrivateIdentifierPropertyOfType(leftType: Type, lexicallyScopedIdentifier: Symbol): Symbol | undefined { + return getPropertyOfType(leftType, lexicallyScopedIdentifier.escapedName); + } + + function checkPrivateIdentifierPropertyAccess(leftType: Type, right: PrivateIdentifier, lexicallyScopedIdentifier: Symbol | undefined): boolean { + // Either the identifier could not be looked up in the lexical scope OR the lexically scoped identifier did not exist on the type. + // Find a private identifier with the same description on the type. + let propertyOnType: Symbol | undefined; + const properties = getPropertiesOfType(leftType); + if (properties) { + forEach(properties, (symbol: Symbol) => { + const decl = symbol.valueDeclaration; + if (decl && isNamedDeclaration(decl) && isPrivateIdentifier(decl.name) && decl.name.escapedText === right.escapedText) { + propertyOnType = symbol; + return true; + } + }); + } + const diagName = diagnosticName(right); + if (propertyOnType) { + const typeValueDecl = Debug.checkDefined(propertyOnType.valueDeclaration); + const typeClass = Debug.checkDefined(getContainingClass(typeValueDecl)); + // We found a private identifier property with the same description. + // Either: + // - There is a lexically scoped private identifier AND it shadows the one we found on the type. + // - It is an attempt to access the private identifier outside of the class. + if (lexicallyScopedIdentifier?.valueDeclaration) { + const lexicalValueDecl = lexicallyScopedIdentifier.valueDeclaration; + const lexicalClass = getContainingClass(lexicalValueDecl); + Debug.assert(!!lexicalClass); + if (findAncestor(lexicalClass, n => typeClass === n)) { + const diagnostic = error( + right, + Diagnostics.The_property_0_cannot_be_accessed_on_type_1_within_this_class_because_it_is_shadowed_by_another_private_identifier_with_the_same_spelling, + diagName, + typeToString(leftType), + ); + + addRelatedInfo( + diagnostic, + createDiagnosticForNode( + lexicalValueDecl, + Diagnostics.The_shadowing_declaration_of_0_is_defined_here, + diagName, + ), + createDiagnosticForNode( + typeValueDecl, + Diagnostics.The_declaration_of_0_that_you_probably_intended_to_use_is_defined_here, + diagName, + ), + ); + return true; + } + } + error( + right, + Diagnostics.Property_0_is_not_accessible_outside_class_1_because_it_has_a_private_identifier, + diagName, + diagnosticName(typeClass.name || anon), + ); + return true; + } + return false; + } + + function isThisPropertyAccessInConstructor(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol) { + return (isConstructorDeclaredProperty(prop) || isThisProperty(node) && isAutoTypedProperty(prop)) + && getThisContainer(node, /*includeArrowFunctions*/ true, /*includeClassComputedPropertyName*/ false) === getDeclaringConstructor(prop); + } + + function checkPropertyAccessExpressionOrQualifiedName(node: PropertyAccessExpression | QualifiedName, left: Expression | QualifiedName, leftType: Type, right: Identifier | PrivateIdentifier, checkMode: CheckMode | undefined, writeOnly?: boolean) { + const parentSymbol = getNodeLinks(left).resolvedSymbol; + const assignmentKind = getAssignmentTargetKind(node); + const apparentType = getApparentType(assignmentKind !== AssignmentKind.None || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType); + const isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType; + let prop: Symbol | undefined; + if (isPrivateIdentifier(right)) { + if ( + languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators || + !useDefineForClassFields + ) { + if (assignmentKind !== AssignmentKind.None) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ClassPrivateFieldSet); + } + if (assignmentKind !== AssignmentKind.Definite) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ClassPrivateFieldGet); + } + } + + const lexicallyScopedSymbol = lookupSymbolForPrivateIdentifierDeclaration(right.escapedText, right); + if (assignmentKind && lexicallyScopedSymbol && lexicallyScopedSymbol.valueDeclaration && isMethodDeclaration(lexicallyScopedSymbol.valueDeclaration)) { + grammarErrorOnNode(right, Diagnostics.Cannot_assign_to_private_method_0_Private_methods_are_not_writable, idText(right)); + } + if (isAnyLike) { + if (lexicallyScopedSymbol) { + return isErrorType(apparentType) ? errorType : apparentType; + } + if (getContainingClassExcludingClassDecorators(right) === undefined) { + grammarErrorOnNode(right, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + return anyType; + } + } + + prop = lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(leftType, lexicallyScopedSymbol); + if (prop === undefined) { + // Check for private-identifier-specific shadowing and lexical-scoping errors. + if (checkPrivateIdentifierPropertyAccess(leftType, right, lexicallyScopedSymbol)) { + return errorType; + } + const containingClass = getContainingClassExcludingClassDecorators(right); + if (containingClass && isPlainJsFile(getSourceFileOfNode(containingClass), compilerOptions.checkJs)) { + grammarErrorOnNode(right, Diagnostics.Private_field_0_must_be_declared_in_an_enclosing_class, idText(right)); + } + } + else { + const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); + if (isSetonlyAccessor && assignmentKind !== AssignmentKind.Definite) { + error(node, Diagnostics.Private_accessor_was_defined_without_a_getter); + } + } + } + else { + if (isAnyLike) { + if (isIdentifier(left) && parentSymbol) { + markLinkedReferences(node, ReferenceHint.Property, /*propSymbol*/ undefined, leftType); + } + return isErrorType(apparentType) ? errorType : apparentType; + } + prop = getPropertyOfType(apparentType, right.escapedText, /*skipObjectFunctionPropertyAugment*/ isConstEnumObjectType(apparentType), /*includeTypeOnlyMembers*/ node.kind === SyntaxKind.QualifiedName); + } + markLinkedReferences(node, ReferenceHint.Property, prop, leftType); + + let propType: Type; + if (!prop) { + const indexInfo = !isPrivateIdentifier(right) && (assignmentKind === AssignmentKind.None || !isGenericObjectType(leftType) || isThisTypeParameter(leftType)) ? + getApplicableIndexInfoForName(apparentType, right.escapedText) : undefined; + if (!(indexInfo && indexInfo.type)) { + const isUncheckedJS = isUncheckedJSSuggestion(node, leftType.symbol, /*excludeClasses*/ true); + if (!isUncheckedJS && isJSLiteralType(leftType)) { + return anyType; + } + if (leftType.symbol === globalThisSymbol) { + if (globalThisSymbol.exports!.has(right.escapedText) && (globalThisSymbol.exports!.get(right.escapedText)!.flags & SymbolFlags.BlockScoped)) { + error(right, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(right.escapedText), typeToString(leftType)); + } + else if (noImplicitAny) { + error(right, Diagnostics.Element_implicitly_has_an_any_type_because_type_0_has_no_index_signature, typeToString(leftType)); + } + return anyType; + } + if (right.escapedText && !checkAndReportErrorForExtendingInterface(node)) { + reportNonexistentProperty(right, isThisTypeParameter(leftType) ? apparentType : leftType, isUncheckedJS); + } + return errorType; + } + if (indexInfo.isReadonly && (isAssignmentTarget(node) || isDeleteTarget(node))) { + error(node, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(apparentType)); + } + + propType = indexInfo.type; + if (compilerOptions.noUncheckedIndexedAccess && getAssignmentTargetKind(node) !== AssignmentKind.Definite) { + propType = getUnionType([propType, missingType]); + } + if (compilerOptions.noPropertyAccessFromIndexSignature && isPropertyAccessExpression(node)) { + error(right, Diagnostics.Property_0_comes_from_an_index_signature_so_it_must_be_accessed_with_0, unescapeLeadingUnderscores(right.escapedText)); + } + if (indexInfo.declaration && isDeprecatedDeclaration(indexInfo.declaration)) { + addDeprecatedSuggestion(right, [indexInfo.declaration], right.escapedText as string); + } + } + else { + const targetPropSymbol = resolveAliasWithDeprecationCheck(prop, right); + if (isDeprecatedSymbol(targetPropSymbol) && isUncalledFunctionReference(node, targetPropSymbol) && targetPropSymbol.declarations) { + addDeprecatedSuggestion(right, targetPropSymbol.declarations, right.escapedText as string); + } + checkPropertyNotUsedBeforeDeclaration(prop, node, right); + markPropertyAsReferenced(prop, node, isSelfTypeAccess(left, parentSymbol)); + getNodeLinks(node).resolvedSymbol = prop; + checkPropertyAccessibility(node, left.kind === SyntaxKind.SuperKeyword, isWriteAccess(node), apparentType, prop); + if (isAssignmentToReadonlyEntity(node as Expression, prop, assignmentKind)) { + error(right, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, idText(right)); + return errorType; + } + + propType = isThisPropertyAccessInConstructor(node, prop) ? autoType : writeOnly || isWriteOnlyAccess(node) ? getWriteTypeOfSymbol(prop) : getTypeOfSymbol(prop); + } + + return getFlowTypeOfAccessExpression(node, prop, propType, right, checkMode); + } + + /** + * Determines whether a did-you-mean error should be a suggestion in an unchecked JS file. + * Only applies to unchecked JS files without checkJS, // @ts-check or // @ts-nocheck + * It does not suggest when the suggestion: + * - Is from a global file that is different from the reference file, or + * - (optionally) Is a class, or is a this.x property access expression + */ + function isUncheckedJSSuggestion(node: Node | undefined, suggestion: Symbol | undefined, excludeClasses: boolean): boolean { + const file = getSourceFileOfNode(node); + if (file) { + if (compilerOptions.checkJs === undefined && file.checkJsDirective === undefined && (file.scriptKind === ScriptKind.JS || file.scriptKind === ScriptKind.JSX)) { + const declarationFile = forEach(suggestion?.declarations, getSourceFileOfNode); + const suggestionHasNoExtendsOrDecorators = !suggestion?.valueDeclaration + || !isClassLike(suggestion.valueDeclaration) + || suggestion.valueDeclaration.heritageClauses?.length + || classOrConstructorParameterIsDecorated(/*useLegacyDecorators*/ false, suggestion.valueDeclaration); + return !(file !== declarationFile && !!declarationFile && isGlobalSourceFile(declarationFile)) + && !(excludeClasses && suggestion && suggestion.flags & SymbolFlags.Class && suggestionHasNoExtendsOrDecorators) + && !(!!node && excludeClasses && isPropertyAccessExpression(node) && node.expression.kind === SyntaxKind.ThisKeyword && suggestionHasNoExtendsOrDecorators); + } + } + return false; + } + + function getFlowTypeOfAccessExpression(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol | undefined, propType: Type, errorNode: Node, checkMode: CheckMode | undefined) { + // Only compute control flow type if this is a property access expression that isn't an + // assignment target, and the referenced property was declared as a variable, property, + // accessor, or optional method. + const assignmentKind = getAssignmentTargetKind(node); + if (assignmentKind === AssignmentKind.Definite) { + return removeMissingType(propType, !!(prop && prop.flags & SymbolFlags.Optional)); + } + if ( + prop && + !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) + && !(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union) + && !isDuplicatedCommonJSExport(prop.declarations) + ) { + return propType; + } + if (propType === autoType) { + return getFlowTypeOfProperty(node, prop); + } + propType = getNarrowableTypeForReference(propType, node, checkMode); + // If strict null checks and strict property initialization checks are enabled, if we have + // a this.xxx property access, if the property is an instance property without an initializer, + // and if we are in a constructor of the same class as the property declaration, assume that + // the property is uninitialized at the top of the control flow. + let assumeUninitialized = false; + if (strictNullChecks && strictPropertyInitialization && isAccessExpression(node) && node.expression.kind === SyntaxKind.ThisKeyword) { + const declaration = prop && prop.valueDeclaration; + if (declaration && isPropertyWithoutInitializer(declaration)) { + if (!isStatic(declaration)) { + const flowContainer = getControlFlowContainer(node); + if (flowContainer.kind === SyntaxKind.Constructor && flowContainer.parent === declaration.parent && !(declaration.flags & NodeFlags.Ambient)) { + assumeUninitialized = true; + } + } + } + } + else if ( + strictNullChecks && prop && prop.valueDeclaration && + isPropertyAccessExpression(prop.valueDeclaration) && + getAssignmentDeclarationPropertyAccessKind(prop.valueDeclaration) && + getControlFlowContainer(node) === getControlFlowContainer(prop.valueDeclaration) + ) { + assumeUninitialized = true; + } + const flowType = getFlowTypeOfReference(node, propType, assumeUninitialized ? getOptionalType(propType) : propType); + if (assumeUninitialized && !containsUndefinedType(propType) && containsUndefinedType(flowType)) { + error(errorNode, Diagnostics.Property_0_is_used_before_being_assigned, symbolToString(prop!)); // TODO: GH#18217 + // Return the declared type to reduce follow-on errors + return propType; + } + return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType; + } + + function checkPropertyNotUsedBeforeDeclaration(prop: Symbol, node: PropertyAccessExpression | QualifiedName, right: Identifier | PrivateIdentifier): void { + const { valueDeclaration } = prop; + if (!valueDeclaration || getSourceFileOfNode(node).isDeclarationFile) { + return; + } + + let diagnosticMessage; + const declarationName = idText(right); + if ( + isInPropertyInitializerOrClassStaticBlock(node) + && !isOptionalPropertyDeclaration(valueDeclaration) + && !(isAccessExpression(node) && isAccessExpression(node.expression)) + && !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right) + && !(isMethodDeclaration(valueDeclaration) && getCombinedModifierFlagsCached(valueDeclaration) & ModifierFlags.Static) + && (useDefineForClassFields || !isPropertyDeclaredInAncestorClass(prop)) + ) { + diagnosticMessage = error(right, Diagnostics.Property_0_is_used_before_its_initialization, declarationName); + } + else if ( + valueDeclaration.kind === SyntaxKind.ClassDeclaration && + node.parent.kind !== SyntaxKind.TypeReference && + !(valueDeclaration.flags & NodeFlags.Ambient) && + !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right) + ) { + diagnosticMessage = error(right, Diagnostics.Class_0_used_before_its_declaration, declarationName); + } + + if (diagnosticMessage) { + addRelatedInfo(diagnosticMessage, createDiagnosticForNode(valueDeclaration, Diagnostics._0_is_declared_here, declarationName)); + } + } + + function isInPropertyInitializerOrClassStaticBlock(node: Node): boolean { + return !!findAncestor(node, node => { + switch (node.kind) { + case SyntaxKind.PropertyDeclaration: + return true; + case SyntaxKind.PropertyAssignment: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.SpreadAssignment: + case SyntaxKind.ComputedPropertyName: + case SyntaxKind.TemplateSpan: + case SyntaxKind.JsxExpression: + case SyntaxKind.JsxAttribute: + case SyntaxKind.JsxAttributes: + case SyntaxKind.JsxSpreadAttribute: + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.ExpressionWithTypeArguments: + case SyntaxKind.HeritageClause: + return false; + case SyntaxKind.ArrowFunction: + case SyntaxKind.ExpressionStatement: + return isBlock(node.parent) && isClassStaticBlockDeclaration(node.parent.parent) ? true : "quit"; + default: + return isExpressionNode(node) ? false : "quit"; + } + }); + } + + /** + * It's possible that "prop.valueDeclaration" is a local declaration, but the property was also declared in a superclass. + * In that case we won't consider it used before its declaration, because it gets its value from the superclass' declaration. + */ + function isPropertyDeclaredInAncestorClass(prop: Symbol): boolean { + if (!(prop.parent!.flags & SymbolFlags.Class)) { + return false; + } + let classType: InterfaceType | undefined = getTypeOfSymbol(prop.parent!) as InterfaceType; + while (true) { + classType = classType.symbol && getSuperClass(classType) as InterfaceType | undefined; + if (!classType) { + return false; + } + const superProperty = getPropertyOfType(classType, prop.escapedName); + if (superProperty && superProperty.valueDeclaration) { + return true; + } + } + } + + function getSuperClass(classType: InterfaceType): Type | undefined { + const x = getBaseTypes(classType); + if (x.length === 0) { + return undefined; + } + return getIntersectionType(x); + } + + function reportNonexistentProperty(propNode: Identifier | PrivateIdentifier, containingType: Type, isUncheckedJS: boolean) { + let errorInfo: DiagnosticMessageChain | undefined; + let relatedInfo: Diagnostic | undefined; + if (!isPrivateIdentifier(propNode) && containingType.flags & TypeFlags.Union && !(containingType.flags & TypeFlags.Primitive)) { + for (const subtype of (containingType as UnionType).types) { + if (!getPropertyOfType(subtype, propNode.escapedText) && !getApplicableIndexInfoForName(subtype, propNode.escapedText)) { + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1, declarationNameToString(propNode), typeToString(subtype)); + break; + } + } + } + if (typeHasStaticProperty(propNode.escapedText, containingType)) { + const propName = declarationNameToString(propNode); + const typeName = typeToString(containingType); + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_to_access_the_static_member_2_instead, propName, typeName, typeName + "." + propName); + } + else { + const promisedType = getPromisedTypeOfPromise(containingType); + if (promisedType && getPropertyOfType(promisedType, propNode.escapedText)) { + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1, declarationNameToString(propNode), typeToString(containingType)); + relatedInfo = createDiagnosticForNode(propNode, Diagnostics.Did_you_forget_to_use_await); + } + else { + const missingProperty = declarationNameToString(propNode); + const container = typeToString(containingType); + const libSuggestion = getSuggestedLibForNonExistentProperty(missingProperty, containingType); + if (libSuggestion !== undefined) { + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_2_or_later, missingProperty, container, libSuggestion); + } + else { + const suggestion = getSuggestedSymbolForNonexistentProperty(propNode, containingType); + if (suggestion !== undefined) { + const suggestedName = symbolName(suggestion); + const message = isUncheckedJS ? Diagnostics.Property_0_may_not_exist_on_type_1_Did_you_mean_2 : Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2; + errorInfo = chainDiagnosticMessages(errorInfo, message, missingProperty, container, suggestedName); + relatedInfo = suggestion.valueDeclaration && createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestedName); + } + else { + const diagnostic = containerSeemsToBeEmptyDomElement(containingType) + ? Diagnostics.Property_0_does_not_exist_on_type_1_Try_changing_the_lib_compiler_option_to_include_dom + : Diagnostics.Property_0_does_not_exist_on_type_1; + errorInfo = chainDiagnosticMessages(elaborateNeverIntersection(errorInfo, containingType), diagnostic, missingProperty, container); + } + } + } + } + const resultDiagnostic = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(propNode), propNode, errorInfo); + if (relatedInfo) { + addRelatedInfo(resultDiagnostic, relatedInfo); + } + addErrorOrSuggestion(!isUncheckedJS || errorInfo.code !== Diagnostics.Property_0_may_not_exist_on_type_1_Did_you_mean_2.code, resultDiagnostic); + } + + function containerSeemsToBeEmptyDomElement(containingType: Type) { + return (compilerOptions.lib && !compilerOptions.lib.includes("dom")) && + everyContainedType(containingType, type => type.symbol && /^(EventTarget|Node|((HTML[a-zA-Z]*)?Element))$/.test(unescapeLeadingUnderscores(type.symbol.escapedName))) && + isEmptyObjectType(containingType); + } + + function typeHasStaticProperty(propName: __String, containingType: Type): boolean { + const prop = containingType.symbol && getPropertyOfType(getTypeOfSymbol(containingType.symbol), propName); + return prop !== undefined && !!prop.valueDeclaration && isStatic(prop.valueDeclaration); + } + + function getSuggestedLibForNonExistentName(name: __String | Identifier) { + const missingName = diagnosticName(name); + const allFeatures = getScriptTargetFeatures(); + const typeFeatures = allFeatures.get(missingName); + return typeFeatures && firstIterator(typeFeatures.keys()); + } + + function getSuggestedLibForNonExistentProperty(missingProperty: string, containingType: Type) { + const container = getApparentType(containingType).symbol; + if (!container) { + return undefined; + } + const containingTypeName = symbolName(container); + const allFeatures = getScriptTargetFeatures(); + const typeFeatures = allFeatures.get(containingTypeName); + if (typeFeatures) { + for (const [libTarget, featuresOfType] of typeFeatures) { + if (contains(featuresOfType, missingProperty)) { + return libTarget; + } + } + } + } + + function getSuggestedSymbolForNonexistentClassMember(name: string, baseType: Type): Symbol | undefined { + return getSpellingSuggestionForName(name, getPropertiesOfType(baseType), SymbolFlags.ClassMember); + } + + function getSuggestedSymbolForNonexistentProperty(name: Identifier | PrivateIdentifier | string, containingType: Type): Symbol | undefined { + let props = getPropertiesOfType(containingType); + if (typeof name !== "string") { + const parent = name.parent; + if (isPropertyAccessExpression(parent)) { + props = filter(props, prop => isValidPropertyAccessForCompletions(parent, containingType, prop)); + } + name = idText(name); + } + return getSpellingSuggestionForName(name, props, SymbolFlags.Value); + } + + function getSuggestedSymbolForNonexistentJSXAttribute(name: Identifier | PrivateIdentifier | string, containingType: Type): Symbol | undefined { + const strName = isString(name) ? name : idText(name); + const properties = getPropertiesOfType(containingType); + const jsxSpecific = strName === "for" ? find(properties, x => symbolName(x) === "htmlFor") + : strName === "class" ? find(properties, x => symbolName(x) === "className") + : undefined; + return jsxSpecific ?? getSpellingSuggestionForName(strName, properties, SymbolFlags.Value); + } + + function getSuggestionForNonexistentProperty(name: Identifier | PrivateIdentifier | string, containingType: Type): string | undefined { + const suggestion = getSuggestedSymbolForNonexistentProperty(name, containingType); + return suggestion && symbolName(suggestion); + } + + function getSuggestionForSymbolNameLookup(symbols: SymbolTable, name: __String, meaning: SymbolFlags) { + const symbol = getSymbol(symbols, name, meaning); + // Sometimes the symbol is found when location is a return type of a function: `typeof x` and `x` is declared in the body of the function + // So the table *contains* `x` but `x` isn't actually in scope. + // However, resolveNameHelper will continue and call this callback again, so we'll eventually get a correct suggestion. + if (symbol) return symbol; + let candidates: Symbol[]; + if (symbols === globals) { + const primitives = mapDefined( + ["string", "number", "boolean", "object", "bigint", "symbol"], + s => symbols.has((s.charAt(0).toUpperCase() + s.slice(1)) as __String) + ? createSymbol(SymbolFlags.TypeAlias, s as __String) as Symbol + : undefined, + ); + candidates = primitives.concat(arrayFrom(symbols.values())); + } + else { + candidates = arrayFrom(symbols.values()); + } + return getSpellingSuggestionForName(unescapeLeadingUnderscores(name), candidates, meaning); + } + function getSuggestedSymbolForNonexistentSymbol(location: Node | undefined, outerName: __String, meaning: SymbolFlags): Symbol | undefined { + Debug.assert(outerName !== undefined, "outername should always be defined"); + const result = resolveNameForSymbolSuggestion(location, outerName, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false, /*excludeGlobals*/ false); + return result; + } + + function getSuggestedSymbolForNonexistentModule(name: Identifier, targetModule: Symbol): Symbol | undefined { + return targetModule.exports && getSpellingSuggestionForName(idText(name), getExportsOfModuleAsArray(targetModule), SymbolFlags.ModuleMember); + } + + function getSuggestionForNonexistentIndexSignature(objectType: Type, expr: ElementAccessExpression, keyedType: Type): string | undefined { + // check if object type has setter or getter + function hasProp(name: "set" | "get") { + const prop = getPropertyOfObjectType(objectType, name as __String); + if (prop) { + const s = getSingleCallSignature(getTypeOfSymbol(prop)); + return !!s && getMinArgumentCount(s) >= 1 && isTypeAssignableTo(keyedType, getTypeAtPosition(s, 0)); + } + return false; + } + + const suggestedMethod = isAssignmentTarget(expr) ? "set" : "get"; + if (!hasProp(suggestedMethod)) { + return undefined; + } + + let suggestion = tryGetPropertyAccessOrIdentifierToString(expr.expression); + if (suggestion === undefined) { + suggestion = suggestedMethod; + } + else { + suggestion += "." + suggestedMethod; + } + + return suggestion; + } + + function getSuggestedTypeForNonexistentStringLiteralType(source: StringLiteralType, target: UnionType): StringLiteralType | undefined { + const candidates = target.types.filter((type): type is StringLiteralType => !!(type.flags & TypeFlags.StringLiteral)); + return getSpellingSuggestion(source.value, candidates, type => type.value); + } + + /** + * Given a name and a list of symbols whose names are *not* equal to the name, return a spelling suggestion if there is one that is close enough. + * Names less than length 3 only check for case-insensitive equality, not levenshtein distance. + * + * If there is a candidate that's the same except for case, return that. + * If there is a candidate that's within one edit of the name, return that. + * Otherwise, return the candidate with the smallest Levenshtein distance, + * except for candidates: + * * With no name + * * Whose meaning doesn't match the `meaning` parameter. + * * Whose length differs from the target name by more than 0.34 of the length of the name. + * * Whose levenshtein distance is more than 0.4 of the length of the name + * (0.4 allows 1 substitution/transposition for every 5 characters, + * and 1 insertion/deletion at 3 characters) + */ + function getSpellingSuggestionForName(name: string, symbols: Symbol[], meaning: SymbolFlags): Symbol | undefined { + return getSpellingSuggestion(name, symbols, getCandidateName); + + function getCandidateName(candidate: Symbol) { + const candidateName = symbolName(candidate); + if (startsWith(candidateName, '"')) { + return undefined; + } + + if (candidate.flags & meaning) { + return candidateName; + } + + if (candidate.flags & SymbolFlags.Alias) { + const alias = tryResolveAlias(candidate); + if (alias && alias.flags & meaning) { + return candidateName; + } + } + + return undefined; + } + } + + function markPropertyAsReferenced(prop: Symbol, nodeForCheckWriteOnly: Node | undefined, isSelfTypeAccess: boolean) { + const valueDeclaration = prop && (prop.flags & SymbolFlags.ClassMember) && prop.valueDeclaration; + if (!valueDeclaration) { + return; + } + const hasPrivateModifier = hasEffectiveModifier(valueDeclaration, ModifierFlags.Private); + const hasPrivateIdentifier = prop.valueDeclaration && isNamedDeclaration(prop.valueDeclaration) && isPrivateIdentifier(prop.valueDeclaration.name); + if (!hasPrivateModifier && !hasPrivateIdentifier) { + return; + } + if (nodeForCheckWriteOnly && isWriteOnlyAccess(nodeForCheckWriteOnly) && !(prop.flags & SymbolFlags.SetAccessor)) { + return; + } + if (isSelfTypeAccess) { + // Find any FunctionLikeDeclaration because those create a new 'this' binding. But this should only matter for methods (or getters/setters). + const containingMethod = findAncestor(nodeForCheckWriteOnly, isFunctionLikeDeclaration); + if (containingMethod && containingMethod.symbol === prop) { + return; + } + } + + (getCheckFlags(prop) & CheckFlags.Instantiated ? getSymbolLinks(prop).target : prop)!.isReferenced = SymbolFlags.All; + } + + function isSelfTypeAccess(name: Expression | QualifiedName, parent: Symbol | undefined) { + return name.kind === SyntaxKind.ThisKeyword + || !!parent && isEntityNameExpression(name) && parent === getResolvedSymbol(getFirstIdentifier(name)); + } + + function isValidPropertyAccess(node: PropertyAccessExpression | QualifiedName | ImportTypeNode, propertyName: __String): boolean { + switch (node.kind) { + case SyntaxKind.PropertyAccessExpression: + return isValidPropertyAccessWithType(node, node.expression.kind === SyntaxKind.SuperKeyword, propertyName, getWidenedType(checkExpression(node.expression))); + case SyntaxKind.QualifiedName: + return isValidPropertyAccessWithType(node, /*isSuper*/ false, propertyName, getWidenedType(checkExpression(node.left))); + case SyntaxKind.ImportType: + return isValidPropertyAccessWithType(node, /*isSuper*/ false, propertyName, getTypeFromTypeNode(node)); + } + } + + /** + * Checks if an existing property access is valid for completions purposes. + * @param node a property access-like node where we want to check if we can access a property. + * This node does not need to be an access of the property we are checking. + * e.g. in completions, this node will often be an incomplete property access node, as in `foo.`. + * Besides providing a location (i.e. scope) used to check property accessibility, we use this node for + * computing whether this is a `super` property access. + * @param type the type whose property we are checking. + * @param property the accessed property's symbol. + */ + function isValidPropertyAccessForCompletions(node: PropertyAccessExpression | ImportTypeNode | QualifiedName, type: Type, property: Symbol): boolean { + return isPropertyAccessible(node, node.kind === SyntaxKind.PropertyAccessExpression && node.expression.kind === SyntaxKind.SuperKeyword, /*isWrite*/ false, type, property); + // Previously we validated the 'this' type of methods but this adversely affected performance. See #31377 for more context. + } + + function isValidPropertyAccessWithType( + node: PropertyAccessExpression | QualifiedName | ImportTypeNode, + isSuper: boolean, + propertyName: __String, + type: Type, + ): boolean { + // Short-circuiting for improved performance. + if (isTypeAny(type)) { + return true; + } + + const prop = getPropertyOfType(type, propertyName); + return !!prop && isPropertyAccessible(node, isSuper, /*isWrite*/ false, type, prop); + } + + /** + * Checks if a property can be accessed in a location. + * The location is given by the `node` parameter. + * The node does not need to be a property access. + * @param node location where to check property accessibility + * @param isSuper whether to consider this a `super` property access, e.g. `super.foo`. + * @param isWrite whether this is a write access, e.g. `++foo.x`. + * @param containingType type where the property comes from. + * @param property property symbol. + */ + function isPropertyAccessible( + node: Node, + isSuper: boolean, + isWrite: boolean, + containingType: Type, + property: Symbol, + ): boolean { + // Short-circuiting for improved performance. + if (isTypeAny(containingType)) { + return true; + } + + // A #private property access in an optional chain is an error dealt with by the parser. + // The checker does not check for it, so we need to do our own check here. + if (property.valueDeclaration && isPrivateIdentifierClassElementDeclaration(property.valueDeclaration)) { + const declClass = getContainingClass(property.valueDeclaration); + return !isOptionalChain(node) && !!findAncestor(node, parent => parent === declClass); + } + + return checkPropertyAccessibilityAtLocation(node, isSuper, isWrite, containingType, property); + } + + /** + * Return the symbol of the for-in variable declared or referenced by the given for-in statement. + */ + function getForInVariableSymbol(node: ForInStatement): Symbol | undefined { + const initializer = node.initializer; + if (initializer.kind === SyntaxKind.VariableDeclarationList) { + const variable = (initializer as VariableDeclarationList).declarations[0]; + if (variable && !isBindingPattern(variable.name)) { + return getSymbolOfDeclaration(variable); + } + } + else if (initializer.kind === SyntaxKind.Identifier) { + return getResolvedSymbol(initializer as Identifier); + } + return undefined; + } + + /** + * Return true if the given type is considered to have numeric property names. + */ + function hasNumericPropertyNames(type: Type) { + return getIndexInfosOfType(type).length === 1 && !!getIndexInfoOfType(type, numberType); + } + + /** + * Return true if given node is an expression consisting of an identifier (possibly parenthesized) + * that references a for-in variable for an object with numeric property names. + */ + function isForInVariableForNumericPropertyNames(expr: Expression) { + const e = skipParentheses(expr); + if (e.kind === SyntaxKind.Identifier) { + const symbol = getResolvedSymbol(e as Identifier); + if (symbol.flags & SymbolFlags.Variable) { + let child: Node = expr; + let node = expr.parent; + while (node) { + if ( + node.kind === SyntaxKind.ForInStatement && + child === (node as ForInStatement).statement && + getForInVariableSymbol(node as ForInStatement) === symbol && + hasNumericPropertyNames(getTypeOfExpression((node as ForInStatement).expression)) + ) { + return true; + } + child = node; + node = node.parent; + } + } + } + return false; + } + + function checkIndexedAccess(node: ElementAccessExpression, checkMode: CheckMode | undefined): Type { + return node.flags & NodeFlags.OptionalChain ? checkElementAccessChain(node as ElementAccessChain, checkMode) : + checkElementAccessExpression(node, checkNonNullExpression(node.expression), checkMode); + } + + function checkElementAccessChain(node: ElementAccessChain, checkMode: CheckMode | undefined) { + const exprType = checkExpression(node.expression); + const nonOptionalType = getOptionalExpressionType(exprType, node.expression); + return propagateOptionalTypeMarker(checkElementAccessExpression(node, checkNonNullType(nonOptionalType, node.expression), checkMode), node, nonOptionalType !== exprType); + } + + function checkElementAccessExpression(node: ElementAccessExpression, exprType: Type, checkMode: CheckMode | undefined): Type { + const objectType = getAssignmentTargetKind(node) !== AssignmentKind.None || isMethodAccessForCall(node) ? getWidenedType(exprType) : exprType; + const indexExpression = node.argumentExpression; + const indexType = checkExpression(indexExpression); + + if (isErrorType(objectType) || objectType === silentNeverType) { + return objectType; + } + + if (isConstEnumObjectType(objectType) && !isStringLiteralLike(indexExpression)) { + error(indexExpression, Diagnostics.A_const_enum_member_can_only_be_accessed_using_a_string_literal); + return errorType; + } + + const effectiveIndexType = isForInVariableForNumericPropertyNames(indexExpression) ? numberType : indexType; + const assignmentTargetKind = getAssignmentTargetKind(node); + let accessFlags: AccessFlags; + if (assignmentTargetKind === AssignmentKind.None) { + accessFlags = AccessFlags.ExpressionPosition; + } + else { + accessFlags = AccessFlags.Writing | (isGenericObjectType(objectType) && !isThisTypeParameter(objectType) ? AccessFlags.NoIndexSignatures : 0); + if (assignmentTargetKind === AssignmentKind.Compound) { + accessFlags |= AccessFlags.ExpressionPosition; + } + } + const indexedAccessType = getIndexedAccessTypeOrUndefined(objectType, effectiveIndexType, accessFlags, node) || errorType; + return checkIndexedAccessIndexType(getFlowTypeOfAccessExpression(node, getNodeLinks(node).resolvedSymbol, indexedAccessType, indexExpression, checkMode), node); + } + + function callLikeExpressionMayHaveTypeArguments(node: CallLikeExpression): node is CallExpression | NewExpression | TaggedTemplateExpression | JsxOpeningElement { + return isCallOrNewExpression(node) || isTaggedTemplateExpression(node) || isJsxOpeningLikeElement(node); + } + + function resolveUntypedCall(node: CallLikeExpression): Signature { + if (callLikeExpressionMayHaveTypeArguments(node)) { + // Check type arguments even though we will give an error that untyped calls may not accept type arguments. + // This gets us diagnostics for the type arguments and marks them as referenced. + forEach(node.typeArguments, checkSourceElement); + } + + if (node.kind === SyntaxKind.TaggedTemplateExpression) { + checkExpression(node.template); + } + else if (isJsxOpeningLikeElement(node)) { + checkExpression(node.attributes); + } + else if (isBinaryExpression(node)) { + checkExpression(node.left); + } + else if (isCallOrNewExpression(node)) { + forEach(node.arguments, argument => { + checkExpression(argument); + }); + } + return anySignature; + } + + function resolveErrorCall(node: CallLikeExpression): Signature { + resolveUntypedCall(node); + return unknownSignature; + } + + // Re-order candidate signatures into the result array. Assumes the result array to be empty. + // The candidate list orders groups in reverse, but within a group signatures are kept in declaration order + // A nit here is that we reorder only signatures that belong to the same symbol, + // so order how inherited signatures are processed is still preserved. + // interface A { (x: string): void } + // interface B extends A { (x: 'foo'): string } + // const b: B; + // b('foo') // <- here overloads should be processed as [(x:'foo'): string, (x: string): void] + function reorderCandidates(signatures: readonly Signature[], result: Signature[], callChainFlags: SignatureFlags): void { + let lastParent: Node | undefined; + let lastSymbol: Symbol | undefined; + let cutoffIndex = 0; + let index: number | undefined; + let specializedIndex = -1; + let spliceIndex: number; + Debug.assert(!result.length); + for (const signature of signatures) { + const symbol = signature.declaration && getSymbolOfDeclaration(signature.declaration); + const parent = signature.declaration && signature.declaration.parent; + if (!lastSymbol || symbol === lastSymbol) { + if (lastParent && parent === lastParent) { + index = index! + 1; + } + else { + lastParent = parent; + index = cutoffIndex; + } + } + else { + // current declaration belongs to a different symbol + // set cutoffIndex so re-orderings in the future won't change result set from 0 to cutoffIndex + index = cutoffIndex = result.length; + lastParent = parent; + } + lastSymbol = symbol; + + // specialized signatures always need to be placed before non-specialized signatures regardless + // of the cutoff position; see GH#1133 + if (signatureHasLiteralTypes(signature)) { + specializedIndex++; + spliceIndex = specializedIndex; + // The cutoff index always needs to be greater than or equal to the specialized signature index + // in order to prevent non-specialized signatures from being added before a specialized + // signature. + cutoffIndex++; + } + else { + spliceIndex = index; + } + + result.splice(spliceIndex, 0, callChainFlags ? getOptionalCallSignature(signature, callChainFlags) : signature); + } + } + + function isSpreadArgument(arg: Expression | undefined): arg is Expression { + return !!arg && (arg.kind === SyntaxKind.SpreadElement || arg.kind === SyntaxKind.SyntheticExpression && (arg as SyntheticExpression).isSpread); + } + + function getSpreadArgumentIndex(args: readonly Expression[]): number { + return findIndex(args, isSpreadArgument); + } + + function acceptsVoid(t: Type): boolean { + return !!(t.flags & TypeFlags.Void); + } + + function acceptsVoidUndefinedUnknownOrAny(t: Type): boolean { + return !!(t.flags & (TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Unknown | TypeFlags.Any)); + } + + function hasCorrectArity(node: CallLikeExpression, args: readonly Expression[], signature: Signature, signatureHelpTrailingComma = false) { + let argCount: number; + let callIsIncomplete = false; // In incomplete call we want to be lenient when we have too few arguments + let effectiveParameterCount = getParameterCount(signature); + let effectiveMinimumArguments = getMinArgumentCount(signature); + + if (node.kind === SyntaxKind.TaggedTemplateExpression) { + argCount = args.length; + if (node.template.kind === SyntaxKind.TemplateExpression) { + // If a tagged template expression lacks a tail literal, the call is incomplete. + // Specifically, a template only can end in a TemplateTail or a Missing literal. + const lastSpan = last(node.template.templateSpans); // we should always have at least one span. + callIsIncomplete = nodeIsMissing(lastSpan.literal) || !!lastSpan.literal.isUnterminated; + } + else { + // If the template didn't end in a backtick, or its beginning occurred right prior to EOF, + // then this might actually turn out to be a TemplateHead in the future; + // so we consider the call to be incomplete. + const templateLiteral = node.template as LiteralExpression; + Debug.assert(templateLiteral.kind === SyntaxKind.NoSubstitutionTemplateLiteral); + callIsIncomplete = !!templateLiteral.isUnterminated; + } + } + else if (node.kind === SyntaxKind.Decorator) { + argCount = getDecoratorArgumentCount(node, signature); + } + else if (node.kind === SyntaxKind.BinaryExpression) { + argCount = 1; + } + else if (isJsxOpeningLikeElement(node)) { + callIsIncomplete = node.attributes.end === node.end; + if (callIsIncomplete) { + return true; + } + argCount = effectiveMinimumArguments === 0 ? args.length : 1; + effectiveParameterCount = args.length === 0 ? effectiveParameterCount : 1; // class may have argumentless ctor functions - still resolve ctor and compare vs props member type + effectiveMinimumArguments = Math.min(effectiveMinimumArguments, 1); // sfc may specify context argument - handled by framework and not typechecked + } + else if (!node.arguments) { + // This only happens when we have something of the form: 'new C' + Debug.assert(node.kind === SyntaxKind.NewExpression); + return getMinArgumentCount(signature) === 0; + } + else { + argCount = signatureHelpTrailingComma ? args.length + 1 : args.length; + + // If we are missing the close parenthesis, the call is incomplete. + callIsIncomplete = node.arguments.end === node.end; + + // If a spread argument is present, check that it corresponds to a rest parameter or at least that it's in the valid range. + const spreadArgIndex = getSpreadArgumentIndex(args); + if (spreadArgIndex >= 0) { + return spreadArgIndex >= getMinArgumentCount(signature) && (hasEffectiveRestParameter(signature) || spreadArgIndex < getParameterCount(signature)); + } + } + + // Too many arguments implies incorrect arity. + if (!hasEffectiveRestParameter(signature) && argCount > effectiveParameterCount) { + return false; + } + + // If the call is incomplete, we should skip the lower bound check. + // JSX signatures can have extra parameters provided by the library which we don't check + if (callIsIncomplete || argCount >= effectiveMinimumArguments) { + return true; + } + for (let i = argCount; i < effectiveMinimumArguments; i++) { + const type = getTypeAtPosition(signature, i); + if (filterType(type, isInJSFile(node) && !strictNullChecks ? acceptsVoidUndefinedUnknownOrAny : acceptsVoid).flags & TypeFlags.Never) { + return false; + } + } + return true; + } + + function hasCorrectTypeArgumentArity(signature: Signature, typeArguments: NodeArray | undefined) { + // If the user supplied type arguments, but the number of type arguments does not match + // the declared number of type parameters, the call has an incorrect arity. + const numTypeParameters = length(signature.typeParameters); + const minTypeArgumentCount = getMinTypeArgumentCount(signature.typeParameters); + return !some(typeArguments) || + (typeArguments.length >= minTypeArgumentCount && typeArguments.length <= numTypeParameters); + } + + function isInstantiatedGenericParameter(signature: Signature, pos: number) { + let type; + return !!(signature.target && (type = tryGetTypeAtPosition(signature.target, pos)) && isGenericType(type)); + } + + // If type has a single call signature and no other members, return that signature. Otherwise, return undefined. + function getSingleCallSignature(type: Type): Signature | undefined { + return getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ false); + } + + function getSingleCallOrConstructSignature(type: Type): Signature | undefined { + return getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ false) || + getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ false); + } + + function getSingleSignature(type: Type, kind: SignatureKind, allowMembers: boolean): Signature | undefined { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + if (allowMembers || resolved.properties.length === 0 && resolved.indexInfos.length === 0) { + if (kind === SignatureKind.Call && resolved.callSignatures.length === 1 && resolved.constructSignatures.length === 0) { + return resolved.callSignatures[0]; + } + if (kind === SignatureKind.Construct && resolved.constructSignatures.length === 1 && resolved.callSignatures.length === 0) { + return resolved.constructSignatures[0]; + } + } + } + return undefined; + } + + // Instantiate a generic signature in the context of a non-generic signature (section 3.8.5 in TypeScript spec) + function instantiateSignatureInContextOf(signature: Signature, contextualSignature: Signature, inferenceContext?: InferenceContext, compareTypes?: TypeComparer): Signature { + const context = createInferenceContext(signature.typeParameters!, signature, InferenceFlags.None, compareTypes); + // We clone the inferenceContext to avoid fixing. For example, when the source signature is (x: T) => T[] and + // the contextual signature is (...args: A) => B, we want to infer the element type of A's constraint (say 'any') + // for T but leave it possible to later infer '[any]' back to A. + const restType = getEffectiveRestType(contextualSignature); + const mapper = inferenceContext && (restType && restType.flags & TypeFlags.TypeParameter ? inferenceContext.nonFixingMapper : inferenceContext.mapper); + const sourceSignature = mapper ? instantiateSignature(contextualSignature, mapper) : contextualSignature; + applyToParameterTypes(sourceSignature, signature, (source, target) => { + // Type parameters from outer context referenced by source type are fixed by instantiation of the source type + inferTypes(context.inferences, source, target); + }); + if (!inferenceContext) { + applyToReturnTypes(contextualSignature, signature, (source, target) => { + inferTypes(context.inferences, source, target, InferencePriority.ReturnType); + }); + } + return getSignatureInstantiation(signature, getInferredTypes(context), isInJSFile(contextualSignature.declaration)); + } + + function inferJsxTypeArguments(node: JsxOpeningLikeElement, signature: Signature, checkMode: CheckMode, context: InferenceContext): Type[] { + const paramType = getEffectiveFirstArgumentForJsxSignature(signature, node); + const checkAttrType = checkExpressionWithContextualType(node.attributes, paramType, context, checkMode); + inferTypes(context.inferences, checkAttrType, paramType); + return getInferredTypes(context); + } + + function getThisArgumentType(thisArgumentNode: Expression | undefined) { + if (!thisArgumentNode) { + return voidType; + } + const thisArgumentType = checkExpression(thisArgumentNode); + return isRightSideOfInstanceofExpression(thisArgumentNode) ? thisArgumentType : + isOptionalChainRoot(thisArgumentNode.parent) ? getNonNullableType(thisArgumentType) : + isOptionalChain(thisArgumentNode.parent) ? removeOptionalTypeMarker(thisArgumentType) : + thisArgumentType; + } + + function inferTypeArguments(node: CallLikeExpression, signature: Signature, args: readonly Expression[], checkMode: CheckMode, context: InferenceContext): Type[] { + if (isJsxOpeningLikeElement(node)) { + return inferJsxTypeArguments(node, signature, checkMode, context); + } + + // If a contextual type is available, infer from that type to the return type of the call expression. For + // example, given a 'function wrap(cb: (x: T) => U): (x: T) => U' and a call expression + // 'let f: (x: string) => number = wrap(s => s.length)', we infer from the declared type of 'f' to the + // return type of 'wrap'. + if (node.kind !== SyntaxKind.Decorator && node.kind !== SyntaxKind.BinaryExpression) { + const skipBindingPatterns = every(signature.typeParameters, p => !!getDefaultFromTypeParameter(p)); + const contextualType = getContextualType(node, skipBindingPatterns ? ContextFlags.SkipBindingPatterns : ContextFlags.None); + if (contextualType) { + const inferenceTargetType = getReturnTypeOfSignature(signature); + if (couldContainTypeVariables(inferenceTargetType)) { + const outerContext = getInferenceContext(node); + const isFromBindingPattern = !skipBindingPatterns && getContextualType(node, ContextFlags.SkipBindingPatterns) !== contextualType; + // A return type inference from a binding pattern can be used in instantiating the contextual + // type of an argument later in inference, but cannot stand on its own as the final return type. + // It is incorporated into `context.returnMapper` which is used in `instantiateContextualType`, + // but doesn't need to go into `context.inferences`. This allows a an array binding pattern to + // produce a tuple for `T` in + // declare function f(cb: () => T): T; + // const [e1, e2, e3] = f(() => [1, "hi", true]); + // but does not produce any inference for `T` in + // declare function f(): T; + // const [e1, e2, e3] = f(); + if (!isFromBindingPattern) { + // We clone the inference context to avoid disturbing a resolution in progress for an + // outer call expression. Effectively we just want a snapshot of whatever has been + // inferred for any outer call expression so far. + const outerMapper = getMapperFromContext(cloneInferenceContext(outerContext, InferenceFlags.NoDefault)); + const instantiatedType = instantiateType(contextualType, outerMapper); + // If the contextual type is a generic function type with a single call signature, we + // instantiate the type with its own type parameters and type arguments. This ensures that + // the type parameters are not erased to type any during type inference such that they can + // be inferred as actual types from the contextual type. For example: + // declare function arrayMap(f: (x: T) => U): (a: T[]) => U[]; + // const boxElements: (a: A[]) => { value: A }[] = arrayMap(value => ({ value })); + // Above, the type of the 'value' parameter is inferred to be 'A'. + const contextualSignature = getSingleCallSignature(instantiatedType); + const inferenceSourceType = contextualSignature && contextualSignature.typeParameters ? + getOrCreateTypeFromSignature(getSignatureInstantiationWithoutFillingInTypeArguments(contextualSignature, contextualSignature.typeParameters)) : + instantiatedType; + // Inferences made from return types have lower priority than all other inferences. + inferTypes(context.inferences, inferenceSourceType, inferenceTargetType, InferencePriority.ReturnType); + } + // Create a type mapper for instantiating generic contextual types using the inferences made + // from the return type. We need a separate inference pass here because (a) instantiation of + // the source type uses the outer context's return mapper (which excludes inferences made from + // outer arguments), and (b) we don't want any further inferences going into this context. + const returnContext = createInferenceContext(signature.typeParameters!, signature, context.flags); + const returnSourceType = instantiateType(contextualType, outerContext && outerContext.returnMapper); + inferTypes(returnContext.inferences, returnSourceType, inferenceTargetType); + context.returnMapper = some(returnContext.inferences, hasInferenceCandidates) ? getMapperFromContext(cloneInferredPartOfContext(returnContext)) : undefined; + } + } + } + + const restType = getNonArrayRestType(signature); + const argCount = restType ? Math.min(getParameterCount(signature) - 1, args.length) : args.length; + if (restType && restType.flags & TypeFlags.TypeParameter) { + const info = find(context.inferences, info => info.typeParameter === restType); + if (info) { + info.impliedArity = findIndex(args, isSpreadArgument, argCount) < 0 ? args.length - argCount : undefined; + } + } + + const thisType = getThisTypeOfSignature(signature); + if (thisType && couldContainTypeVariables(thisType)) { + const thisArgumentNode = getThisArgumentOfCall(node); + inferTypes(context.inferences, getThisArgumentType(thisArgumentNode), thisType); + } + + for (let i = 0; i < argCount; i++) { + const arg = args[i]; + if (arg.kind !== SyntaxKind.OmittedExpression) { + const paramType = getTypeAtPosition(signature, i); + if (couldContainTypeVariables(paramType)) { + const argType = checkExpressionWithContextualType(arg, paramType, context, checkMode); + inferTypes(context.inferences, argType, paramType); + } + } + } + + if (restType && couldContainTypeVariables(restType)) { + const spreadType = getSpreadArgumentType(args, argCount, args.length, restType, context, checkMode); + inferTypes(context.inferences, spreadType, restType); + } + + return getInferredTypes(context); + } + + function getMutableArrayOrTupleType(type: Type) { + return type.flags & TypeFlags.Union ? mapType(type, getMutableArrayOrTupleType) : + type.flags & TypeFlags.Any || isMutableArrayOrTuple(getBaseConstraintOfType(type) || type) ? type : + isTupleType(type) ? createTupleType(getElementTypes(type), type.target.elementFlags, /*readonly*/ false, type.target.labeledElementDeclarations) : + createTupleType([type], [ElementFlags.Variadic]); + } + + function getSpreadArgumentType(args: readonly Expression[], index: number, argCount: number, restType: Type, context: InferenceContext | undefined, checkMode: CheckMode) { + const inConstContext = isConstTypeVariable(restType); + + if (index >= argCount - 1) { + const arg = args[argCount - 1]; + if (isSpreadArgument(arg)) { + // We are inferring from a spread expression in the last argument position, i.e. both the parameter + // and the argument are ...x forms. + const spreadType = arg.kind === SyntaxKind.SyntheticExpression ? (arg as SyntheticExpression).type : + checkExpressionWithContextualType((arg as SpreadElement).expression, restType, context, checkMode); + + if (isArrayLikeType(spreadType)) { + return getMutableArrayOrTupleType(spreadType); + } + + return createArrayType(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, arg.kind === SyntaxKind.SpreadElement ? (arg as SpreadElement).expression : arg), inConstContext); + } + } + const types = []; + const flags = []; + const names = []; + for (let i = index; i < argCount; i++) { + const arg = args[i]; + if (isSpreadArgument(arg)) { + const spreadType = arg.kind === SyntaxKind.SyntheticExpression ? (arg as SyntheticExpression).type : checkExpression((arg as SpreadElement).expression); + if (isArrayLikeType(spreadType)) { + types.push(spreadType); + flags.push(ElementFlags.Variadic); + } + else { + types.push(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, arg.kind === SyntaxKind.SpreadElement ? (arg as SpreadElement).expression : arg)); + flags.push(ElementFlags.Rest); + } + } + else { + const contextualType = isTupleType(restType) ? + getContextualTypeForElementExpression(restType, i - index, argCount - index) || unknownType : + getIndexedAccessType(restType, getNumberLiteralType(i - index), AccessFlags.Contextual); + const argType = checkExpressionWithContextualType(arg, contextualType, context, checkMode); + const hasPrimitiveContextualType = inConstContext || maybeTypeOfKind(contextualType, TypeFlags.Primitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping); + types.push(hasPrimitiveContextualType ? getRegularTypeOfLiteralType(argType) : getWidenedLiteralType(argType)); + flags.push(ElementFlags.Required); + } + if (arg.kind === SyntaxKind.SyntheticExpression && (arg as SyntheticExpression).tupleNameSource) { + names.push((arg as SyntheticExpression).tupleNameSource!); + } + else { + names.push(undefined); + } + } + return createTupleType(types, flags, inConstContext && !someType(restType, isMutableArrayLikeType), names); + } + + function checkTypeArguments(signature: Signature, typeArgumentNodes: readonly TypeNode[], reportErrors: boolean, headMessage?: DiagnosticMessage): Type[] | undefined { + const isJavascript = isInJSFile(signature.declaration); + const typeParameters = signature.typeParameters!; + const typeArgumentTypes = fillMissingTypeArguments(map(typeArgumentNodes, getTypeFromTypeNode), typeParameters, getMinTypeArgumentCount(typeParameters), isJavascript); + let mapper: TypeMapper | undefined; + for (let i = 0; i < typeArgumentNodes.length; i++) { + Debug.assert(typeParameters[i] !== undefined, "Should not call checkTypeArguments with too many type arguments"); + const constraint = getConstraintOfTypeParameter(typeParameters[i]); + if (constraint) { + const errorInfo = reportErrors && headMessage ? (() => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Type_0_does_not_satisfy_the_constraint_1)) : undefined; + const typeArgumentHeadMessage = headMessage || Diagnostics.Type_0_does_not_satisfy_the_constraint_1; + if (!mapper) { + mapper = createTypeMapper(typeParameters, typeArgumentTypes); + } + const typeArgument = typeArgumentTypes[i]; + if ( + !checkTypeAssignableTo( + typeArgument, + getTypeWithThisArgument(instantiateType(constraint, mapper), typeArgument), + reportErrors ? typeArgumentNodes[i] : undefined, + typeArgumentHeadMessage, + errorInfo, + ) + ) { + return undefined; + } + } + } + return typeArgumentTypes; + } + + function getJsxReferenceKind(node: JsxOpeningLikeElement): JsxReferenceKind { + if (isJsxIntrinsicTagName(node.tagName)) { + return JsxReferenceKind.Mixed; + } + const tagType = getApparentType(checkExpression(node.tagName)); + if (length(getSignaturesOfType(tagType, SignatureKind.Construct))) { + return JsxReferenceKind.Component; + } + if (length(getSignaturesOfType(tagType, SignatureKind.Call))) { + return JsxReferenceKind.Function; + } + return JsxReferenceKind.Mixed; + } + + /** + * Check if the given signature can possibly be a signature called by the JSX opening-like element. + * @param node a JSX opening-like element we are trying to figure its call signature + * @param signature a candidate signature we are trying whether it is a call signature + * @param relation a relationship to check parameter and argument type + */ + function checkApplicableSignatureForJsxOpeningLikeElement( + node: JsxOpeningLikeElement, + signature: Signature, + relation: Map, + checkMode: CheckMode, + reportErrors: boolean, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; }, + ) { + // Stateless function components can have maximum of three arguments: "props", "context", and "updater". + // However "context" and "updater" are implicit and can't be specify by users. Only the first parameter, props, + // can be specified by users through attributes property. + const paramType = getEffectiveFirstArgumentForJsxSignature(signature, node); + const attributesType = checkExpressionWithContextualType(node.attributes, paramType, /*inferenceContext*/ undefined, checkMode); + const checkAttributesType = checkMode & CheckMode.SkipContextSensitive ? getRegularTypeOfObjectLiteral(attributesType) : attributesType; + return checkTagNameDoesNotExpectTooManyArguments() && checkTypeRelatedToAndOptionallyElaborate( + checkAttributesType, + paramType, + relation, + reportErrors ? node.tagName : undefined, + node.attributes, + /*headMessage*/ undefined, + containingMessageChain, + errorOutputContainer, + ); + + function checkTagNameDoesNotExpectTooManyArguments(): boolean { + if (getJsxNamespaceContainerForImplicitImport(node)) { + return true; // factory is implicitly jsx/jsxdev - assume it fits the bill, since we don't strongly look for the jsx/jsxs/jsxDEV factory APIs anywhere else (at least not yet) + } + const tagType = (isJsxOpeningElement(node) || isJsxSelfClosingElement(node)) && !(isJsxIntrinsicTagName(node.tagName) || isJsxNamespacedName(node.tagName)) ? checkExpression(node.tagName) : undefined; + if (!tagType) { + return true; + } + const tagCallSignatures = getSignaturesOfType(tagType, SignatureKind.Call); + if (!length(tagCallSignatures)) { + return true; + } + const factory = getJsxFactoryEntity(node); + if (!factory) { + return true; + } + const factorySymbol = resolveEntityName(factory, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ false, node); + if (!factorySymbol) { + return true; + } + + const factoryType = getTypeOfSymbol(factorySymbol); + const callSignatures = getSignaturesOfType(factoryType, SignatureKind.Call); + if (!length(callSignatures)) { + return true; + } + + let hasFirstParamSignatures = false; + let maxParamCount = 0; + // Check that _some_ first parameter expects a FC-like thing, and that some overload of the SFC expects an acceptable number of arguments + for (const sig of callSignatures) { + const firstparam = getTypeAtPosition(sig, 0); + const signaturesOfParam = getSignaturesOfType(firstparam, SignatureKind.Call); + if (!length(signaturesOfParam)) continue; + for (const paramSig of signaturesOfParam) { + hasFirstParamSignatures = true; + if (hasEffectiveRestParameter(paramSig)) { + return true; // some signature has a rest param, so function components can have an arbitrary number of arguments + } + const paramCount = getParameterCount(paramSig); + if (paramCount > maxParamCount) { + maxParamCount = paramCount; + } + } + } + if (!hasFirstParamSignatures) { + // Not a single signature had a first parameter which expected a signature - for back compat, and + // to guard against generic factories which won't have signatures directly, do not error + return true; + } + let absoluteMinArgCount = Infinity; + for (const tagSig of tagCallSignatures) { + const tagRequiredArgCount = getMinArgumentCount(tagSig); + if (tagRequiredArgCount < absoluteMinArgCount) { + absoluteMinArgCount = tagRequiredArgCount; + } + } + if (absoluteMinArgCount <= maxParamCount) { + return true; // some signature accepts the number of arguments the function component provides + } + + if (reportErrors) { + const diag = createDiagnosticForNode(node.tagName, Diagnostics.Tag_0_expects_at_least_1_arguments_but_the_JSX_factory_2_provides_at_most_3, entityNameToString(node.tagName), absoluteMinArgCount, entityNameToString(factory), maxParamCount); + const tagNameDeclaration = getSymbolAtLocation(node.tagName)?.valueDeclaration; + if (tagNameDeclaration) { + addRelatedInfo(diag, createDiagnosticForNode(tagNameDeclaration, Diagnostics._0_is_declared_here, entityNameToString(node.tagName))); + } + if (errorOutputContainer && errorOutputContainer.skipLogging) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + if (!errorOutputContainer.skipLogging) { + diagnostics.add(diag); + } + } + return false; + } + } + + function getEffectiveCheckNode(argument: Expression): Expression { + argument = skipParentheses(argument); + return isSatisfiesExpression(argument) ? skipParentheses(argument.expression) : argument; + } + + function getSignatureApplicabilityError( + node: CallLikeExpression, + args: readonly Expression[], + signature: Signature, + relation: Map, + checkMode: CheckMode, + reportErrors: boolean, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + inferenceContext: InferenceContext | undefined, + ): readonly Diagnostic[] | undefined { + const errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } = { errors: undefined, skipLogging: true }; + if (isJsxOpeningLikeElement(node)) { + if (!checkApplicableSignatureForJsxOpeningLikeElement(node, signature, relation, checkMode, reportErrors, containingMessageChain, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "jsx should have errors when reporting errors"); + return errorOutputContainer.errors || emptyArray; + } + return undefined; + } + const thisType = getThisTypeOfSignature(signature); + if (thisType && thisType !== voidType && !(isNewExpression(node) || isCallExpression(node) && isSuperProperty(node.expression))) { + // If the called expression is not of the form `x.f` or `x["f"]`, then sourceType = voidType + // If the signature's 'this' type is voidType, then the check is skipped -- anything is compatible. + // If the expression is a new expression or super call expression, then the check is skipped. + const thisArgumentNode = getThisArgumentOfCall(node); + const thisArgumentType = getThisArgumentType(thisArgumentNode); + const errorNode = reportErrors ? (thisArgumentNode || node) : undefined; + const headMessage = Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1; + if (!checkTypeRelatedTo(thisArgumentType, thisType, relation, errorNode, headMessage, containingMessageChain, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "this parameter should have errors when reporting errors"); + return errorOutputContainer.errors || emptyArray; + } + } + const headMessage = Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1; + const restType = getNonArrayRestType(signature); + const argCount = restType ? Math.min(getParameterCount(signature) - 1, args.length) : args.length; + for (let i = 0; i < argCount; i++) { + const arg = args[i]; + if (arg.kind !== SyntaxKind.OmittedExpression) { + const paramType = getTypeAtPosition(signature, i); + const argType = checkExpressionWithContextualType(arg, paramType, /*inferenceContext*/ undefined, checkMode); + // If one or more arguments are still excluded (as indicated by CheckMode.SkipContextSensitive), + // we obtain the regular type of any object literal arguments because we may not have inferred complete + // parameter types yet and therefore excess property checks may yield false positives (see #17041). + const regularArgType = checkMode & CheckMode.SkipContextSensitive ? getRegularTypeOfObjectLiteral(argType) : argType; + // If this was inferred under a given inference context, we may need to instantiate the expression type to finish resolving + // the type variables in the expression. + const checkArgType = inferenceContext ? instantiateType(regularArgType, inferenceContext.nonFixingMapper) : regularArgType; + const effectiveCheckArgumentNode = getEffectiveCheckNode(arg); + if (!checkTypeRelatedToAndOptionallyElaborate(checkArgType, paramType, relation, reportErrors ? effectiveCheckArgumentNode : undefined, effectiveCheckArgumentNode, headMessage, containingMessageChain, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "parameter should have errors when reporting errors"); + maybeAddMissingAwaitInfo(arg, checkArgType, paramType); + return errorOutputContainer.errors || emptyArray; + } + } + } + if (restType) { + const spreadType = getSpreadArgumentType(args, argCount, args.length, restType, /*context*/ undefined, checkMode); + const restArgCount = args.length - argCount; + const errorNode = !reportErrors ? undefined : + restArgCount === 0 ? node : + restArgCount === 1 ? getEffectiveCheckNode(args[argCount]) : + setTextRangePosEnd(createSyntheticExpression(node, spreadType), args[argCount].pos, args[args.length - 1].end); + if (!checkTypeRelatedTo(spreadType, restType, relation, errorNode, headMessage, /*containingMessageChain*/ undefined, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "rest parameter should have errors when reporting errors"); + maybeAddMissingAwaitInfo(errorNode, spreadType, restType); + return errorOutputContainer.errors || emptyArray; + } + } + return undefined; + + function maybeAddMissingAwaitInfo(errorNode: Node | undefined, source: Type, target: Type) { + if (errorNode && reportErrors && errorOutputContainer.errors && errorOutputContainer.errors.length) { + // Bail if target is Promise-like---something else is wrong + if (getAwaitedTypeOfPromise(target)) { + return; + } + const awaitedTypeOfSource = getAwaitedTypeOfPromise(source); + if (awaitedTypeOfSource && isTypeRelatedTo(awaitedTypeOfSource, target, relation)) { + addRelatedInfo(errorOutputContainer.errors[0], createDiagnosticForNode(errorNode, Diagnostics.Did_you_forget_to_use_await)); + } + } + } + } + + /** + * Returns the this argument in calls like x.f(...) and x[f](...). Undefined otherwise. + */ + function getThisArgumentOfCall(node: CallLikeExpression): Expression | undefined { + if (node.kind === SyntaxKind.BinaryExpression) { + return node.right; + } + + const expression = node.kind === SyntaxKind.CallExpression ? node.expression : + node.kind === SyntaxKind.TaggedTemplateExpression ? node.tag : + node.kind === SyntaxKind.Decorator && !legacyDecorators ? node.expression : + undefined; + if (expression) { + const callee = skipOuterExpressions(expression); + if (isAccessExpression(callee)) { + return callee.expression; + } + } + } + + function createSyntheticExpression(parent: Node, type: Type, isSpread?: boolean, tupleNameSource?: ParameterDeclaration | NamedTupleMember) { + const result = parseNodeFactory.createSyntheticExpression(type, isSpread, tupleNameSource); + setTextRangeWorker(result, parent); + setParent(result, parent); + return result; + } + + /** + * Returns the effective arguments for an expression that works like a function invocation. + */ + function getEffectiveCallArguments(node: CallLikeExpression): readonly Expression[] { + if (node.kind === SyntaxKind.TaggedTemplateExpression) { + const template = node.template; + const args: Expression[] = [createSyntheticExpression(template, getGlobalTemplateStringsArrayType())]; + if (template.kind === SyntaxKind.TemplateExpression) { + forEach(template.templateSpans, span => { + args.push(span.expression); + }); + } + return args; + } + if (node.kind === SyntaxKind.Decorator) { + return getEffectiveDecoratorArguments(node); + } + if (node.kind === SyntaxKind.BinaryExpression) { + return [node.left]; + } + if (isJsxOpeningLikeElement(node)) { + return node.attributes.properties.length > 0 || (isJsxOpeningElement(node) && node.parent.children.length > 0) ? [node.attributes] : emptyArray; + } + const args = node.arguments || emptyArray; + const spreadIndex = getSpreadArgumentIndex(args); + if (spreadIndex >= 0) { + // Create synthetic arguments from spreads of tuple types. + const effectiveArgs = args.slice(0, spreadIndex); + for (let i = spreadIndex; i < args.length; i++) { + const arg = args[i]; + // We can call checkExpressionCached because spread expressions never have a contextual type. + const spreadType = arg.kind === SyntaxKind.SpreadElement && (flowLoopCount ? checkExpression((arg as SpreadElement).expression) : checkExpressionCached((arg as SpreadElement).expression)); + if (spreadType && isTupleType(spreadType)) { + forEach(getElementTypes(spreadType), (t, i) => { + const flags = spreadType.target.elementFlags[i]; + const syntheticArg = createSyntheticExpression(arg, flags & ElementFlags.Rest ? createArrayType(t) : t, !!(flags & ElementFlags.Variable), spreadType.target.labeledElementDeclarations?.[i]); + effectiveArgs.push(syntheticArg); + }); + } + else { + effectiveArgs.push(arg); + } + } + return effectiveArgs; + } + return args; + } + + /** + * Returns the synthetic argument list for a decorator invocation. + */ + function getEffectiveDecoratorArguments(node: Decorator): readonly Expression[] { + const expr = node.expression; + const signature = getDecoratorCallSignature(node); + if (signature) { + const args: Expression[] = []; + for (const param of signature.parameters) { + const type = getTypeOfSymbol(param); + args.push(createSyntheticExpression(expr, type)); + } + return args; + } + return Debug.fail(); + } + + /** + * Returns the argument count for a decorator node that works like a function invocation. + */ + function getDecoratorArgumentCount(node: Decorator, signature: Signature) { + return compilerOptions.experimentalDecorators ? + getLegacyDecoratorArgumentCount(node, signature) : + // Allow the runtime to oversupply arguments to an ES decorator as long as there's at least one parameter. + Math.min(Math.max(getParameterCount(signature), 1), 2); + } + + /** + * Returns the argument count for a decorator node that works like a function invocation. + */ + function getLegacyDecoratorArgumentCount(node: Decorator, signature: Signature) { + switch (node.parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + return 1; + case SyntaxKind.PropertyDeclaration: + return hasAccessorModifier(node.parent) ? 3 : 2; + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + // For decorators with only two parameters we supply only two arguments + return signature.parameters.length <= 2 ? 2 : 3; + case SyntaxKind.Parameter: + return 3; + default: + return Debug.fail(); + } + } + + function getDiagnosticSpanForCallNode(node: CallExpression) { + const sourceFile = getSourceFileOfNode(node); + const { start, length } = getErrorSpanForNode(sourceFile, isPropertyAccessExpression(node.expression) ? node.expression.name : node.expression); + return { start, length, sourceFile }; + } + + function getDiagnosticForCallNode(node: CallLikeExpression, message: DiagnosticMessage | DiagnosticMessageChain, ...args: DiagnosticArguments): DiagnosticWithLocation { + if (isCallExpression(node)) { + const { sourceFile, start, length } = getDiagnosticSpanForCallNode(node); + if ("message" in message) { // eslint-disable-line local/no-in-operator + return createFileDiagnostic(sourceFile, start, length, message, ...args); + } + return createDiagnosticForFileFromMessageChain(sourceFile, message); + } + else { + if ("message" in message) { // eslint-disable-line local/no-in-operator + return createDiagnosticForNode(node, message, ...args); + } + return createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node), node, message); + } + } + + function getErrorNodeForCallNode(callLike: CallLikeExpression): Node { + if (isCallOrNewExpression(callLike)) { + return isPropertyAccessExpression(callLike.expression) ? callLike.expression.name : callLike.expression; + } + if (isTaggedTemplateExpression(callLike)) { + return isPropertyAccessExpression(callLike.tag) ? callLike.tag.name : callLike.tag; + } + if (isJsxOpeningLikeElement(callLike)) { + return callLike.tagName; + } + return callLike; + } + + function isPromiseResolveArityError(node: CallLikeExpression) { + if (!isCallExpression(node) || !isIdentifier(node.expression)) return false; + + const symbol = resolveName(node.expression, node.expression.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + const decl = symbol?.valueDeclaration; + if (!decl || !isParameter(decl) || !isFunctionExpressionOrArrowFunction(decl.parent) || !isNewExpression(decl.parent.parent) || !isIdentifier(decl.parent.parent.expression)) { + return false; + } + + const globalPromiseSymbol = getGlobalPromiseConstructorSymbol(/*reportErrors*/ false); + if (!globalPromiseSymbol) return false; + + const constructorSymbol = getSymbolAtLocation(decl.parent.parent.expression, /*ignoreErrors*/ true); + return constructorSymbol === globalPromiseSymbol; + } + + function getArgumentArityError(node: CallLikeExpression, signatures: readonly Signature[], args: readonly Expression[], headMessage?: DiagnosticMessage) { + const spreadIndex = getSpreadArgumentIndex(args); + if (spreadIndex > -1) { + return createDiagnosticForNode(args[spreadIndex], Diagnostics.A_spread_argument_must_either_have_a_tuple_type_or_be_passed_to_a_rest_parameter); + } + let min = Number.POSITIVE_INFINITY; // smallest parameter count + let max = Number.NEGATIVE_INFINITY; // largest parameter count + let maxBelow = Number.NEGATIVE_INFINITY; // largest parameter count that is smaller than the number of arguments + let minAbove = Number.POSITIVE_INFINITY; // smallest parameter count that is larger than the number of arguments + + let closestSignature: Signature | undefined; + for (const sig of signatures) { + const minParameter = getMinArgumentCount(sig); + const maxParameter = getParameterCount(sig); + // smallest/largest parameter counts + if (minParameter < min) { + min = minParameter; + closestSignature = sig; + } + max = Math.max(max, maxParameter); + // shortest parameter count *longer than the call*/longest parameter count *shorter than the call* + if (minParameter < args.length && minParameter > maxBelow) maxBelow = minParameter; + if (args.length < maxParameter && maxParameter < minAbove) minAbove = maxParameter; + } + const hasRestParameter = some(signatures, hasEffectiveRestParameter); + const parameterRange = hasRestParameter ? min + : min < max ? min + "-" + max + : min; + const isVoidPromiseError = !hasRestParameter && parameterRange === 1 && args.length === 0 && isPromiseResolveArityError(node); + if (isVoidPromiseError && isInJSFile(node)) { + return getDiagnosticForCallNode(node, Diagnostics.Expected_1_argument_but_got_0_new_Promise_needs_a_JSDoc_hint_to_produce_a_resolve_that_can_be_called_without_arguments); + } + const error = isDecorator(node) ? + hasRestParameter ? Diagnostics.The_runtime_will_invoke_the_decorator_with_1_arguments_but_the_decorator_expects_at_least_0 : + Diagnostics.The_runtime_will_invoke_the_decorator_with_1_arguments_but_the_decorator_expects_0 : + hasRestParameter ? Diagnostics.Expected_at_least_0_arguments_but_got_1 : + isVoidPromiseError ? Diagnostics.Expected_0_arguments_but_got_1_Did_you_forget_to_include_void_in_your_type_argument_to_Promise : + Diagnostics.Expected_0_arguments_but_got_1; + + if (min < args.length && args.length < max) { + // between min and max, but with no matching overload + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_overload_expects_0_arguments_but_overloads_do_exist_that_expect_either_1_or_2_arguments, args.length, maxBelow, minAbove); + chain = chainDiagnosticMessages(chain, headMessage); + return getDiagnosticForCallNode(node, chain); + } + return getDiagnosticForCallNode(node, Diagnostics.No_overload_expects_0_arguments_but_overloads_do_exist_that_expect_either_1_or_2_arguments, args.length, maxBelow, minAbove); + } + else if (args.length < min) { + // too short: put the error span on the call expression, not any of the args + let diagnostic: Diagnostic; + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, error, parameterRange, args.length); + chain = chainDiagnosticMessages(chain, headMessage); + diagnostic = getDiagnosticForCallNode(node, chain); + } + else { + diagnostic = getDiagnosticForCallNode(node, error, parameterRange, args.length); + } + const parameter = closestSignature?.declaration?.parameters[closestSignature.thisParameter ? args.length + 1 : args.length]; + if (parameter) { + const messageAndArgs: DiagnosticAndArguments = isBindingPattern(parameter.name) ? [Diagnostics.An_argument_matching_this_binding_pattern_was_not_provided] + : isRestParameter(parameter) ? [Diagnostics.Arguments_for_the_rest_parameter_0_were_not_provided, idText(getFirstIdentifier(parameter.name))] + : [Diagnostics.An_argument_for_0_was_not_provided, !parameter.name ? args.length : idText(getFirstIdentifier(parameter.name))]; + const parameterError = createDiagnosticForNode(parameter, ...messageAndArgs); + return addRelatedInfo(diagnostic, parameterError); + } + return diagnostic; + } + else { + // too long; error goes on the excess parameters + const errorSpan = factory.createNodeArray(args.slice(max)); + const pos = first(errorSpan).pos; + let end = last(errorSpan).end; + if (end === pos) { + end++; + } + setTextRangePosEnd(errorSpan, pos, end); + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, error, parameterRange, args.length); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), errorSpan, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), errorSpan, error, parameterRange, args.length); + } + } + + function getTypeArgumentArityError(node: Node, signatures: readonly Signature[], typeArguments: NodeArray, headMessage?: DiagnosticMessage) { + const argCount = typeArguments.length; + // No overloads exist + if (signatures.length === 1) { + const sig = signatures[0]; + const min = getMinTypeArgumentCount(sig.typeParameters); + const max = length(sig.typeParameters); + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Expected_0_type_arguments_but_got_1, min < max ? min + "-" + max : min, argCount); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Expected_0_type_arguments_but_got_1, min < max ? min + "-" + max : min, argCount); + } + // Overloads exist + let belowArgCount = -Infinity; + let aboveArgCount = Infinity; + for (const sig of signatures) { + const min = getMinTypeArgumentCount(sig.typeParameters); + const max = length(sig.typeParameters); + if (min > argCount) { + aboveArgCount = Math.min(aboveArgCount, min); + } + else if (max < argCount) { + belowArgCount = Math.max(belowArgCount, max); + } + } + if (belowArgCount !== -Infinity && aboveArgCount !== Infinity) { + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_overload_expects_0_type_arguments_but_overloads_do_exist_that_expect_either_1_or_2_type_arguments, argCount, belowArgCount, aboveArgCount); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.No_overload_expects_0_type_arguments_but_overloads_do_exist_that_expect_either_1_or_2_type_arguments, argCount, belowArgCount, aboveArgCount); + } + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Expected_0_type_arguments_but_got_1, belowArgCount === -Infinity ? aboveArgCount : belowArgCount, argCount); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Expected_0_type_arguments_but_got_1, belowArgCount === -Infinity ? aboveArgCount : belowArgCount, argCount); + } + + function resolveCall(node: CallLikeExpression, signatures: readonly Signature[], candidatesOutArray: Signature[] | undefined, checkMode: CheckMode, callChainFlags: SignatureFlags, headMessage?: DiagnosticMessage): Signature { + const isTaggedTemplate = node.kind === SyntaxKind.TaggedTemplateExpression; + const isDecorator = node.kind === SyntaxKind.Decorator; + const isJsxOpeningOrSelfClosingElement = isJsxOpeningLikeElement(node); + const isInstanceof = node.kind === SyntaxKind.BinaryExpression; + const reportErrors = !isInferencePartiallyBlocked && !candidatesOutArray; + + let typeArguments: NodeArray | undefined; + + if (!isDecorator && !isInstanceof && !isSuperCall(node)) { + typeArguments = (node as CallExpression).typeArguments; + + // We already perform checking on the type arguments on the class declaration itself. + if (isTaggedTemplate || isJsxOpeningOrSelfClosingElement || (node as CallExpression).expression.kind !== SyntaxKind.SuperKeyword) { + forEach(typeArguments, checkSourceElement); + } + } + + const candidates = candidatesOutArray || []; + // reorderCandidates fills up the candidates array directly + reorderCandidates(signatures, candidates, callChainFlags); + Debug.assert(candidates.length, "Revert #54442 and add a testcase with whatever triggered this"); + + const args = getEffectiveCallArguments(node); + + // The excludeArgument array contains true for each context sensitive argument (an argument + // is context sensitive it is susceptible to a one-time permanent contextual typing). + // + // The idea is that we will perform type argument inference & assignability checking once + // without using the susceptible parameters that are functions, and once more for those + // parameters, contextually typing each as we go along. + // + // For a tagged template, then the first argument be 'undefined' if necessary because it + // represents a TemplateStringsArray. + // + // For a decorator, no arguments are susceptible to contextual typing due to the fact + // decorators are applied to a declaration by the emitter, and not to an expression. + const isSingleNonGenericCandidate = candidates.length === 1 && !candidates[0].typeParameters; + let argCheckMode = !isDecorator && !isSingleNonGenericCandidate && some(args, isContextSensitive) ? CheckMode.SkipContextSensitive : CheckMode.Normal; + + // The following variables are captured and modified by calls to chooseOverload. + // If overload resolution or type argument inference fails, we want to report the + // best error possible. The best error is one which says that an argument was not + // assignable to a parameter. This implies that everything else about the overload + // was fine. So if there is any overload that is only incorrect because of an + // argument, we will report an error on that one. + // + // function foo(s: string): void; + // function foo(n: number): void; // Report argument error on this overload + // function foo(): void; + // foo(true); + // + // If none of the overloads even made it that far, there are two possibilities. + // There was a problem with type arguments for some overload, in which case + // report an error on that. Or none of the overloads even had correct arity, + // in which case give an arity error. + // + // function foo(x: T): void; // Report type argument error + // function foo(): void; + // foo(0); + // + let candidatesForArgumentError: Signature[] | undefined; + let candidateForArgumentArityError: Signature | undefined; + let candidateForTypeArgumentError: Signature | undefined; + let result: Signature | undefined; + + // If we are in signature help, a trailing comma indicates that we intend to provide another argument, + // so we will only accept overloads with arity at least 1 higher than the current number of provided arguments. + const signatureHelpTrailingComma = !!(checkMode & CheckMode.IsForSignatureHelp) && node.kind === SyntaxKind.CallExpression && node.arguments.hasTrailingComma; + + // Section 4.12.1: + // if the candidate list contains one or more signatures for which the type of each argument + // expression is a subtype of each corresponding parameter type, the return type of the first + // of those signatures becomes the return type of the function call. + // Otherwise, the return type of the first signature in the candidate list becomes the return + // type of the function call. + // + // Whether the call is an error is determined by assignability of the arguments. The subtype pass + // is just important for choosing the best signature. So in the case where there is only one + // signature, the subtype pass is useless. So skipping it is an optimization. + if (candidates.length > 1) { + result = chooseOverload(candidates, subtypeRelation, isSingleNonGenericCandidate, signatureHelpTrailingComma); + } + if (!result) { + result = chooseOverload(candidates, assignableRelation, isSingleNonGenericCandidate, signatureHelpTrailingComma); + } + if (result) { + return result; + } + + result = getCandidateForOverloadFailure(node, candidates, args, !!candidatesOutArray, checkMode); + // Preemptively cache the result; getResolvedSignature will do this after we return, but + // we need to ensure that the result is present for the error checks below so that if + // this signature is encountered again, we handle the circularity (rather than producing a + // different result which may produce no errors and assert). Callers of getResolvedSignature + // don't hit this issue because they only observe this result after it's had a chance to + // be cached, but the error reporting code below executes before getResolvedSignature sets + // resolvedSignature. + getNodeLinks(node).resolvedSignature = result; + + // No signatures were applicable. Now report errors based on the last applicable signature with + // no arguments excluded from assignability checks. + // If candidate is undefined, it means that no candidates had a suitable arity. In that case, + // skip the checkApplicableSignature check. + if (reportErrors) { + // If the call expression is a synthetic call to a `[Symbol.hasInstance]` method then we will produce a head + // message when reporting diagnostics that explains how we got to `right[Symbol.hasInstance](left)` from + // `left instanceof right`, as it pertains to "Argument" related messages reported for the call. + if (!headMessage && isInstanceof) { + headMessage = Diagnostics.The_left_hand_side_of_an_instanceof_expression_must_be_assignable_to_the_first_argument_of_the_right_hand_side_s_Symbol_hasInstance_method; + } + if (candidatesForArgumentError) { + if (candidatesForArgumentError.length === 1 || candidatesForArgumentError.length > 3) { + const last = candidatesForArgumentError[candidatesForArgumentError.length - 1]; + let chain: DiagnosticMessageChain | undefined; + if (candidatesForArgumentError.length > 3) { + chain = chainDiagnosticMessages(chain, Diagnostics.The_last_overload_gave_the_following_error); + chain = chainDiagnosticMessages(chain, Diagnostics.No_overload_matches_this_call); + } + if (headMessage) { + chain = chainDiagnosticMessages(chain, headMessage); + } + const diags = getSignatureApplicabilityError(node, args, last, assignableRelation, CheckMode.Normal, /*reportErrors*/ true, () => chain, /*inferenceContext*/ undefined); + if (diags) { + for (const d of diags) { + if (last.declaration && candidatesForArgumentError.length > 3) { + addRelatedInfo(d, createDiagnosticForNode(last.declaration, Diagnostics.The_last_overload_is_declared_here)); + } + addImplementationSuccessElaboration(last, d); + diagnostics.add(d); + } + } + else { + Debug.fail("No error for last overload signature"); + } + } + else { + const allDiagnostics: (readonly DiagnosticRelatedInformation[])[] = []; + let max = 0; + let min = Number.MAX_VALUE; + let minIndex = 0; + let i = 0; + for (const c of candidatesForArgumentError) { + const chain = () => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Overload_0_of_1_2_gave_the_following_error, i + 1, candidates.length, signatureToString(c)); + const diags = getSignatureApplicabilityError(node, args, c, assignableRelation, CheckMode.Normal, /*reportErrors*/ true, chain, /*inferenceContext*/ undefined); + if (diags) { + if (diags.length <= min) { + min = diags.length; + minIndex = i; + } + max = Math.max(max, diags.length); + allDiagnostics.push(diags); + } + else { + Debug.fail("No error for 3 or fewer overload signatures"); + } + i++; + } + + const diags = max > 1 ? allDiagnostics[minIndex] : flatten(allDiagnostics); + Debug.assert(diags.length > 0, "No errors reported for 3 or fewer overload signatures"); + let chain = chainDiagnosticMessages( + map(diags, createDiagnosticMessageChainFromDiagnostic), + Diagnostics.No_overload_matches_this_call, + ); + if (headMessage) { + chain = chainDiagnosticMessages(chain, headMessage); + } + // The below is a spread to guarantee we get a new (mutable) array - our `flatMap` helper tries to do "smart" optimizations where it reuses input + // arrays and the emptyArray singleton where possible, which is decidedly not what we want while we're still constructing this diagnostic + const related = [...flatMap(diags, d => (d as Diagnostic).relatedInformation) as DiagnosticRelatedInformation[]]; + let diag: Diagnostic; + if (every(diags, d => d.start === diags[0].start && d.length === diags[0].length && d.file === diags[0].file)) { + const { file, start, length } = diags[0]; + diag = { file, start, length, code: chain.code, category: chain.category, messageText: chain, relatedInformation: related }; + } + else { + diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node), getErrorNodeForCallNode(node), chain, related); + } + addImplementationSuccessElaboration(candidatesForArgumentError[0], diag); + diagnostics.add(diag); + } + } + else if (candidateForArgumentArityError) { + diagnostics.add(getArgumentArityError(node, [candidateForArgumentArityError], args, headMessage)); + } + else if (candidateForTypeArgumentError) { + checkTypeArguments(candidateForTypeArgumentError, (node as CallExpression | TaggedTemplateExpression | JsxOpeningLikeElement).typeArguments!, /*reportErrors*/ true, headMessage); + } + else { + const signaturesWithCorrectTypeArgumentArity = filter(signatures, s => hasCorrectTypeArgumentArity(s, typeArguments)); + if (signaturesWithCorrectTypeArgumentArity.length === 0) { + diagnostics.add(getTypeArgumentArityError(node, signatures, typeArguments!, headMessage)); + } + else { + diagnostics.add(getArgumentArityError(node, signaturesWithCorrectTypeArgumentArity, args, headMessage)); + } + } + } + + return result; + + function addImplementationSuccessElaboration(failed: Signature, diagnostic: Diagnostic) { + const oldCandidatesForArgumentError = candidatesForArgumentError; + const oldCandidateForArgumentArityError = candidateForArgumentArityError; + const oldCandidateForTypeArgumentError = candidateForTypeArgumentError; + + const failedSignatureDeclarations = failed.declaration?.symbol?.declarations || emptyArray; + const isOverload = failedSignatureDeclarations.length > 1; + const implDecl = isOverload ? find(failedSignatureDeclarations, d => isFunctionLikeDeclaration(d) && nodeIsPresent(d.body)) : undefined; + if (implDecl) { + const candidate = getSignatureFromDeclaration(implDecl as FunctionLikeDeclaration); + const isSingleNonGenericCandidate = !candidate.typeParameters; + if (chooseOverload([candidate], assignableRelation, isSingleNonGenericCandidate)) { + addRelatedInfo(diagnostic, createDiagnosticForNode(implDecl, Diagnostics.The_call_would_have_succeeded_against_this_implementation_but_implementation_signatures_of_overloads_are_not_externally_visible)); + } + } + + candidatesForArgumentError = oldCandidatesForArgumentError; + candidateForArgumentArityError = oldCandidateForArgumentArityError; + candidateForTypeArgumentError = oldCandidateForTypeArgumentError; + } + + function chooseOverload(candidates: Signature[], relation: Map, isSingleNonGenericCandidate: boolean, signatureHelpTrailingComma = false) { + candidatesForArgumentError = undefined; + candidateForArgumentArityError = undefined; + candidateForTypeArgumentError = undefined; + + if (isSingleNonGenericCandidate) { + const candidate = candidates[0]; + if (some(typeArguments) || !hasCorrectArity(node, args, candidate, signatureHelpTrailingComma)) { + return undefined; + } + if (getSignatureApplicabilityError(node, args, candidate, relation, CheckMode.Normal, /*reportErrors*/ false, /*containingMessageChain*/ undefined, /*inferenceContext*/ undefined)) { + candidatesForArgumentError = [candidate]; + return undefined; + } + return candidate; + } + + for (let candidateIndex = 0; candidateIndex < candidates.length; candidateIndex++) { + let candidate = candidates[candidateIndex]; + if (!hasCorrectTypeArgumentArity(candidate, typeArguments) || !hasCorrectArity(node, args, candidate, signatureHelpTrailingComma)) { + continue; + } + + let checkCandidate: Signature; + let inferenceContext: InferenceContext | undefined; + + if (candidate.typeParameters) { + // If we are *inside the body of candidate*, we need to create a clone of `candidate` with differing type parameter identities, + // so our inference results for this call doesn't pollute expression types referencing the outer type parameter! + const paramLocation = candidate.typeParameters[0].symbol.declarations?.[0]?.parent; + const candidateParameterContext = paramLocation || (candidate.declaration && isConstructorDeclaration(candidate.declaration) ? candidate.declaration.parent : candidate.declaration); + if (candidateParameterContext && findAncestor(node, a => a === candidateParameterContext)) { + candidate = getImplementationSignature(candidate); + } + let typeArgumentTypes: readonly Type[] | undefined; + if (some(typeArguments)) { + typeArgumentTypes = checkTypeArguments(candidate, typeArguments, /*reportErrors*/ false); + if (!typeArgumentTypes) { + candidateForTypeArgumentError = candidate; + continue; + } + } + else { + inferenceContext = createInferenceContext(candidate.typeParameters!, candidate, /*flags*/ isInJSFile(node) ? InferenceFlags.AnyDefault : InferenceFlags.None); + // The resulting type arguments are instantiated with the inference context mapper, as the inferred types may still contain references to the inference context's + // type variables via contextual projection. These are kept generic until all inferences are locked in, so the dependencies expressed can pass constraint checks. + typeArgumentTypes = instantiateTypes(inferTypeArguments(node, candidate, args, argCheckMode | CheckMode.SkipGenericFunctions, inferenceContext), inferenceContext.nonFixingMapper); + argCheckMode |= inferenceContext.flags & InferenceFlags.SkippedGenericFunction ? CheckMode.SkipGenericFunctions : CheckMode.Normal; + } + checkCandidate = getSignatureInstantiation(candidate, typeArgumentTypes, isInJSFile(candidate.declaration), inferenceContext && inferenceContext.inferredTypeParameters); + // If the original signature has a generic rest type, instantiation may produce a + // signature with different arity and we need to perform another arity check. + if (getNonArrayRestType(candidate) && !hasCorrectArity(node, args, checkCandidate, signatureHelpTrailingComma)) { + candidateForArgumentArityError = checkCandidate; + continue; + } + } + else { + checkCandidate = candidate; + } + if (getSignatureApplicabilityError(node, args, checkCandidate, relation, argCheckMode, /*reportErrors*/ false, /*containingMessageChain*/ undefined, inferenceContext)) { + // Give preference to error candidates that have no rest parameters (as they are more specific) + (candidatesForArgumentError || (candidatesForArgumentError = [])).push(checkCandidate); + continue; + } + if (argCheckMode) { + // If one or more context sensitive arguments were excluded, we start including + // them now (and keeping do so for any subsequent candidates) and perform a second + // round of type inference and applicability checking for this particular candidate. + argCheckMode = CheckMode.Normal; + if (inferenceContext) { + const typeArgumentTypes = instantiateTypes(inferTypeArguments(node, candidate, args, argCheckMode, inferenceContext), inferenceContext.mapper); + checkCandidate = getSignatureInstantiation(candidate, typeArgumentTypes, isInJSFile(candidate.declaration), inferenceContext.inferredTypeParameters); + // If the original signature has a generic rest type, instantiation may produce a + // signature with different arity and we need to perform another arity check. + if (getNonArrayRestType(candidate) && !hasCorrectArity(node, args, checkCandidate, signatureHelpTrailingComma)) { + candidateForArgumentArityError = checkCandidate; + continue; + } + } + if (getSignatureApplicabilityError(node, args, checkCandidate, relation, argCheckMode, /*reportErrors*/ false, /*containingMessageChain*/ undefined, inferenceContext)) { + // Give preference to error candidates that have no rest parameters (as they are more specific) + (candidatesForArgumentError || (candidatesForArgumentError = [])).push(checkCandidate); + continue; + } + } + candidates[candidateIndex] = checkCandidate; + return checkCandidate; + } + + return undefined; + } + } + + // No signature was applicable. We have already reported the errors for the invalid signature. + function getCandidateForOverloadFailure( + node: CallLikeExpression, + candidates: Signature[], + args: readonly Expression[], + hasCandidatesOutArray: boolean, + checkMode: CheckMode, + ): Signature { + Debug.assert(candidates.length > 0); // Else should not have called this. + checkNodeDeferred(node); + // Normally we will combine overloads. Skip this if they have type parameters since that's hard to combine. + // Don't do this if there is a `candidatesOutArray`, + // because then we want the chosen best candidate to be one of the overloads, not a combination. + return hasCandidatesOutArray || candidates.length === 1 || candidates.some(c => !!c.typeParameters) + ? pickLongestCandidateSignature(node, candidates, args, checkMode) + : createUnionOfSignaturesForOverloadFailure(candidates); + } + + function createUnionOfSignaturesForOverloadFailure(candidates: readonly Signature[]): Signature { + const thisParameters = mapDefined(candidates, c => c.thisParameter); + let thisParameter: Symbol | undefined; + if (thisParameters.length) { + thisParameter = createCombinedSymbolFromTypes(thisParameters, thisParameters.map(getTypeOfParameter)); + } + const { min: minArgumentCount, max: maxNonRestParam } = minAndMax(candidates, getNumNonRestParameters); + const parameters: Symbol[] = []; + for (let i = 0; i < maxNonRestParam; i++) { + const symbols = mapDefined(candidates, s => + signatureHasRestParameter(s) ? + i < s.parameters.length - 1 ? s.parameters[i] : last(s.parameters) : + i < s.parameters.length ? s.parameters[i] : undefined); + Debug.assert(symbols.length !== 0); + parameters.push(createCombinedSymbolFromTypes(symbols, mapDefined(candidates, candidate => tryGetTypeAtPosition(candidate, i)))); + } + const restParameterSymbols = mapDefined(candidates, c => signatureHasRestParameter(c) ? last(c.parameters) : undefined); + let flags = SignatureFlags.IsSignatureCandidateForOverloadFailure; + if (restParameterSymbols.length !== 0) { + const type = createArrayType(getUnionType(mapDefined(candidates, tryGetRestTypeOfSignature), UnionReduction.Subtype)); + parameters.push(createCombinedSymbolForOverloadFailure(restParameterSymbols, type)); + flags |= SignatureFlags.HasRestParameter; + } + if (candidates.some(signatureHasLiteralTypes)) { + flags |= SignatureFlags.HasLiteralTypes; + } + return createSignature( + candidates[0].declaration, + /*typeParameters*/ undefined, // Before calling this we tested for `!candidates.some(c => !!c.typeParameters)`. + thisParameter, + parameters, + /*resolvedReturnType*/ getIntersectionType(candidates.map(getReturnTypeOfSignature)), + /*resolvedTypePredicate*/ undefined, + minArgumentCount, + flags, + ); + } + + function getNumNonRestParameters(signature: Signature): number { + const numParams = signature.parameters.length; + return signatureHasRestParameter(signature) ? numParams - 1 : numParams; + } + + function createCombinedSymbolFromTypes(sources: readonly Symbol[], types: Type[]): Symbol { + return createCombinedSymbolForOverloadFailure(sources, getUnionType(types, UnionReduction.Subtype)); + } + + function createCombinedSymbolForOverloadFailure(sources: readonly Symbol[], type: Type): Symbol { + // This function is currently only used for erroneous overloads, so it's good enough to just use the first source. + return createSymbolWithType(first(sources), type); + } + + function pickLongestCandidateSignature(node: CallLikeExpression, candidates: Signature[], args: readonly Expression[], checkMode: CheckMode): Signature { + // Pick the longest signature. This way we can get a contextual type for cases like: + // declare function f(a: { xa: number; xb: number; }, b: number); + // f({ | + // Also, use explicitly-supplied type arguments if they are provided, so we can get a contextual signature in cases like: + // declare function f(k: keyof T); + // f(" + const bestIndex = getLongestCandidateIndex(candidates, apparentArgumentCount === undefined ? args.length : apparentArgumentCount); + const candidate = candidates[bestIndex]; + const { typeParameters } = candidate; + if (!typeParameters) { + return candidate; + } + + const typeArgumentNodes: readonly TypeNode[] | undefined = callLikeExpressionMayHaveTypeArguments(node) ? node.typeArguments : undefined; + const instantiated = typeArgumentNodes + ? createSignatureInstantiation(candidate, getTypeArgumentsFromNodes(typeArgumentNodes, typeParameters, isInJSFile(node))) + : inferSignatureInstantiationForOverloadFailure(node, typeParameters, candidate, args, checkMode); + candidates[bestIndex] = instantiated; + return instantiated; + } + + function getTypeArgumentsFromNodes(typeArgumentNodes: readonly TypeNode[], typeParameters: readonly TypeParameter[], isJs: boolean): readonly Type[] { + const typeArguments = typeArgumentNodes.map(getTypeOfNode); + while (typeArguments.length > typeParameters.length) { + typeArguments.pop(); + } + while (typeArguments.length < typeParameters.length) { + typeArguments.push(getDefaultFromTypeParameter(typeParameters[typeArguments.length]) || getConstraintOfTypeParameter(typeParameters[typeArguments.length]) || getDefaultTypeArgumentType(isJs)); + } + return typeArguments; + } + + function inferSignatureInstantiationForOverloadFailure(node: CallLikeExpression, typeParameters: readonly TypeParameter[], candidate: Signature, args: readonly Expression[], checkMode: CheckMode): Signature { + const inferenceContext = createInferenceContext(typeParameters, candidate, /*flags*/ isInJSFile(node) ? InferenceFlags.AnyDefault : InferenceFlags.None); + const typeArgumentTypes = inferTypeArguments(node, candidate, args, checkMode | CheckMode.SkipContextSensitive | CheckMode.SkipGenericFunctions, inferenceContext); + return createSignatureInstantiation(candidate, typeArgumentTypes); + } + + function getLongestCandidateIndex(candidates: Signature[], argsCount: number): number { + let maxParamsIndex = -1; + let maxParams = -1; + + for (let i = 0; i < candidates.length; i++) { + const candidate = candidates[i]; + const paramCount = getParameterCount(candidate); + if (hasEffectiveRestParameter(candidate) || paramCount >= argsCount) { + return i; + } + if (paramCount > maxParams) { + maxParams = paramCount; + maxParamsIndex = i; + } + } + + return maxParamsIndex; + } + + function resolveCallExpression(node: CallExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + if (node.expression.kind === SyntaxKind.SuperKeyword) { + const superType = checkSuperExpression(node.expression); + if (isTypeAny(superType)) { + for (const arg of node.arguments) { + checkExpression(arg); // Still visit arguments so they get marked for visibility, etc + } + return anySignature; + } + if (!isErrorType(superType)) { + // In super call, the candidate signatures are the matching arity signatures of the base constructor function instantiated + // with the type arguments specified in the extends clause. + const baseTypeNode = getEffectiveBaseTypeNode(getContainingClass(node)!); + if (baseTypeNode) { + const baseConstructors = getInstantiatedConstructorsForTypeArguments(superType, baseTypeNode.typeArguments, baseTypeNode); + return resolveCall(node, baseConstructors, candidatesOutArray, checkMode, SignatureFlags.None); + } + } + return resolveUntypedCall(node); + } + + let callChainFlags: SignatureFlags; + let funcType = checkExpression(node.expression); + if (isCallChain(node)) { + const nonOptionalType = getOptionalExpressionType(funcType, node.expression); + callChainFlags = nonOptionalType === funcType ? SignatureFlags.None : + isOutermostOptionalChain(node) ? SignatureFlags.IsOuterCallChain : + SignatureFlags.IsInnerCallChain; + funcType = nonOptionalType; + } + else { + callChainFlags = SignatureFlags.None; + } + + funcType = checkNonNullTypeWithReporter( + funcType, + node.expression, + reportCannotInvokePossiblyNullOrUndefinedError, + ); + + if (funcType === silentNeverType) { + return silentNeverSignature; + } + + const apparentType = getApparentType(funcType); + if (isErrorType(apparentType)) { + // Another error has already been reported + return resolveErrorCall(node); + } + + // Technically, this signatures list may be incomplete. We are taking the apparent type, + // but we are not including call signatures that may have been added to the Object or + // Function interface, since they have none by default. This is a bit of a leap of faith + // that the user will not add any. + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; + + // TS 1.0 Spec: 4.12 + // In an untyped function call no TypeArgs are permitted, Args can be any argument list, no contextual + // types are provided for the argument expressions, and the result is always of type Any. + if (isUntypedFunctionCall(funcType, apparentType, callSignatures.length, numConstructSignatures)) { + // The unknownType indicates that an error already occurred (and was reported). No + // need to report another error in this case. + if (!isErrorType(funcType) && node.typeArguments) { + error(node, Diagnostics.Untyped_function_calls_may_not_accept_type_arguments); + } + return resolveUntypedCall(node); + } + // If FuncExpr's apparent type(section 3.8.1) is a function type, the call is a typed function call. + // TypeScript employs overload resolution in typed function calls in order to support functions + // with multiple call signatures. + if (!callSignatures.length) { + if (numConstructSignatures) { + error(node, Diagnostics.Value_of_type_0_is_not_callable_Did_you_mean_to_include_new, typeToString(funcType)); + } + else { + let relatedInformation: DiagnosticRelatedInformation | undefined; + if (node.arguments.length === 1) { + const text = getSourceFileOfNode(node).text; + if (isLineBreak(text.charCodeAt(skipTrivia(text, node.expression.end, /*stopAfterLineBreak*/ true) - 1))) { + relatedInformation = createDiagnosticForNode(node.expression, Diagnostics.Are_you_missing_a_semicolon); + } + } + invocationError(node.expression, apparentType, SignatureKind.Call, relatedInformation); + } + return resolveErrorCall(node); + } + // When a call to a generic function is an argument to an outer call to a generic function for which + // inference is in process, we have a choice to make. If the inner call relies on inferences made from + // its contextual type to its return type, deferring the inner call processing allows the best possible + // contextual type to accumulate. But if the outer call relies on inferences made from the return type of + // the inner call, the inner call should be processed early. There's no sure way to know which choice is + // right (only a full unification algorithm can determine that), so we resort to the following heuristic: + // If no type arguments are specified in the inner call and at least one call signature is generic and + // returns a function type, we choose to defer processing. This narrowly permits function composition + // operators to flow inferences through return types, but otherwise processes calls right away. We + // use the resolvingSignature singleton to indicate that we deferred processing. This result will be + // propagated out and eventually turned into silentNeverType (a type that is assignable to anything and + // from which we never make inferences). + if (checkMode & CheckMode.SkipGenericFunctions && !node.typeArguments && callSignatures.some(isGenericFunctionReturningFunction)) { + skippedGenericFunction(node, checkMode); + return resolvingSignature; + } + // If the function is explicitly marked with `@class`, then it must be constructed. + if (callSignatures.some(sig => isInJSFile(sig.declaration) && !!getJSDocClassTag(sig.declaration!))) { + error(node, Diagnostics.Value_of_type_0_is_not_callable_Did_you_mean_to_include_new, typeToString(funcType)); + return resolveErrorCall(node); + } + + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, callChainFlags); + } + + function isGenericFunctionReturningFunction(signature: Signature) { + return !!(signature.typeParameters && isFunctionType(getReturnTypeOfSignature(signature))); + } + + /** + * TS 1.0 spec: 4.12 + * If FuncExpr is of type Any, or of an object type that has no call or construct signatures + * but is a subtype of the Function interface, the call is an untyped function call. + */ + function isUntypedFunctionCall(funcType: Type, apparentFuncType: Type, numCallSignatures: number, numConstructSignatures: number): boolean { + // We exclude union types because we may have a union of function types that happen to have no common signatures. + return isTypeAny(funcType) || isTypeAny(apparentFuncType) && !!(funcType.flags & TypeFlags.TypeParameter) || + !numCallSignatures && !numConstructSignatures && !(apparentFuncType.flags & TypeFlags.Union) && !(getReducedType(apparentFuncType).flags & TypeFlags.Never) && isTypeAssignableTo(funcType, globalFunctionType); + } + + function resolveNewExpression(node: NewExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + let expressionType = checkNonNullExpression(node.expression); + if (expressionType === silentNeverType) { + return silentNeverSignature; + } + + // If expressionType's apparent type(section 3.8.1) is an object type with one or + // more construct signatures, the expression is processed in the same manner as a + // function call, but using the construct signatures as the initial set of candidate + // signatures for overload resolution. The result type of the function call becomes + // the result type of the operation. + expressionType = getApparentType(expressionType); + if (isErrorType(expressionType)) { + // Another error has already been reported + return resolveErrorCall(node); + } + + // TS 1.0 spec: 4.11 + // If expressionType is of type Any, Args can be any argument + // list and the result of the operation is of type Any. + if (isTypeAny(expressionType)) { + if (node.typeArguments) { + error(node, Diagnostics.Untyped_function_calls_may_not_accept_type_arguments); + } + return resolveUntypedCall(node); + } + + // Technically, this signatures list may be incomplete. We are taking the apparent type, + // but we are not including construct signatures that may have been added to the Object or + // Function interface, since they have none by default. This is a bit of a leap of faith + // that the user will not add any. + const constructSignatures = getSignaturesOfType(expressionType, SignatureKind.Construct); + if (constructSignatures.length) { + if (!isConstructorAccessible(node, constructSignatures[0])) { + return resolveErrorCall(node); + } + // If the expression is a class of abstract type, or an abstract construct signature, + // then it cannot be instantiated. + // In the case of a merged class-module or class-interface declaration, + // only the class declaration node will have the Abstract flag set. + if (someSignature(constructSignatures, signature => !!(signature.flags & SignatureFlags.Abstract))) { + error(node, Diagnostics.Cannot_create_an_instance_of_an_abstract_class); + return resolveErrorCall(node); + } + const valueDecl = expressionType.symbol && getClassLikeDeclarationOfSymbol(expressionType.symbol); + if (valueDecl && hasSyntacticModifier(valueDecl, ModifierFlags.Abstract)) { + error(node, Diagnostics.Cannot_create_an_instance_of_an_abstract_class); + return resolveErrorCall(node); + } + + return resolveCall(node, constructSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + + // If expressionType's apparent type is an object type with no construct signatures but + // one or more call signatures, the expression is processed as a function call. A compile-time + // error occurs if the result of the function call is not Void. The type of the result of the + // operation is Any. It is an error to have a Void this type. + const callSignatures = getSignaturesOfType(expressionType, SignatureKind.Call); + if (callSignatures.length) { + const signature = resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + if (!noImplicitAny) { + if (signature.declaration && !isJSConstructor(signature.declaration) && getReturnTypeOfSignature(signature) !== voidType) { + error(node, Diagnostics.Only_a_void_function_can_be_called_with_the_new_keyword); + } + if (getThisTypeOfSignature(signature) === voidType) { + error(node, Diagnostics.A_function_that_is_called_with_the_new_keyword_cannot_have_a_this_type_that_is_void); + } + } + return signature; + } + + invocationError(node.expression, expressionType, SignatureKind.Construct); + return resolveErrorCall(node); + } + + function someSignature(signatures: Signature | readonly Signature[], f: (s: Signature) => boolean): boolean { + if (isArray(signatures)) { + return some(signatures, signature => someSignature(signature, f)); + } + return signatures.compositeKind === TypeFlags.Union ? some(signatures.compositeSignatures, f) : f(signatures); + } + + function typeHasProtectedAccessibleBase(target: Symbol, type: InterfaceType): boolean { + const baseTypes = getBaseTypes(type); + if (!length(baseTypes)) { + return false; + } + const firstBase = baseTypes[0]; + if (firstBase.flags & TypeFlags.Intersection) { + const types = (firstBase as IntersectionType).types; + const mixinFlags = findMixins(types); + let i = 0; + for (const intersectionMember of (firstBase as IntersectionType).types) { + // We want to ignore mixin ctors + if (!mixinFlags[i]) { + if (getObjectFlags(intersectionMember) & (ObjectFlags.Class | ObjectFlags.Interface)) { + if (intersectionMember.symbol === target) { + return true; + } + if (typeHasProtectedAccessibleBase(target, intersectionMember as InterfaceType)) { + return true; + } + } + } + i++; + } + return false; + } + if (firstBase.symbol === target) { + return true; + } + return typeHasProtectedAccessibleBase(target, firstBase as InterfaceType); + } + + function isConstructorAccessible(node: NewExpression, signature: Signature) { + if (!signature || !signature.declaration) { + return true; + } + + const declaration = signature.declaration; + const modifiers = getSelectedEffectiveModifierFlags(declaration, ModifierFlags.NonPublicAccessibilityModifier); + + // (1) Public constructors and (2) constructor functions are always accessible. + if (!modifiers || declaration.kind !== SyntaxKind.Constructor) { + return true; + } + + const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(declaration.parent.symbol)!; + const declaringClass = getDeclaredTypeOfSymbol(declaration.parent.symbol) as InterfaceType; + + // A private or protected constructor can only be instantiated within its own class (or a subclass, for protected) + if (!isNodeWithinClass(node, declaringClassDeclaration)) { + const containingClass = getContainingClass(node); + if (containingClass && modifiers & ModifierFlags.Protected) { + const containingType = getTypeOfNode(containingClass); + if (typeHasProtectedAccessibleBase(declaration.parent.symbol, containingType as InterfaceType)) { + return true; + } + } + if (modifiers & ModifierFlags.Private) { + error(node, Diagnostics.Constructor_of_class_0_is_private_and_only_accessible_within_the_class_declaration, typeToString(declaringClass)); + } + if (modifiers & ModifierFlags.Protected) { + error(node, Diagnostics.Constructor_of_class_0_is_protected_and_only_accessible_within_the_class_declaration, typeToString(declaringClass)); + } + return false; + } + + return true; + } + + function invocationErrorDetails(errorTarget: Node, apparentType: Type, kind: SignatureKind): { messageChain: DiagnosticMessageChain; relatedMessage: DiagnosticMessage | undefined; } { + let errorInfo: DiagnosticMessageChain | undefined; + const isCall = kind === SignatureKind.Call; + const awaitedType = getAwaitedType(apparentType); + const maybeMissingAwait = awaitedType && getSignaturesOfType(awaitedType, kind).length > 0; + if (apparentType.flags & TypeFlags.Union) { + const types = (apparentType as UnionType).types; + let hasSignatures = false; + for (const constituent of types) { + const signatures = getSignaturesOfType(constituent, kind); + if (signatures.length !== 0) { + hasSignatures = true; + if (errorInfo) { + // Bail early if we already have an error, no chance of "No constituent of type is callable" + break; + } + } + else { + // Error on the first non callable constituent only + if (!errorInfo) { + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Type_0_has_no_call_signatures : + Diagnostics.Type_0_has_no_construct_signatures, + typeToString(constituent), + ); + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Not_all_constituents_of_type_0_are_callable : + Diagnostics.Not_all_constituents_of_type_0_are_constructable, + typeToString(apparentType), + ); + } + if (hasSignatures) { + // Bail early if we already found a siganture, no chance of "No constituent of type is callable" + break; + } + } + } + if (!hasSignatures) { + errorInfo = chainDiagnosticMessages( + /*details*/ undefined, + isCall ? + Diagnostics.No_constituent_of_type_0_is_callable : + Diagnostics.No_constituent_of_type_0_is_constructable, + typeToString(apparentType), + ); + } + if (!errorInfo) { + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Each_member_of_the_union_type_0_has_signatures_but_none_of_those_signatures_are_compatible_with_each_other : + Diagnostics.Each_member_of_the_union_type_0_has_construct_signatures_but_none_of_those_signatures_are_compatible_with_each_other, + typeToString(apparentType), + ); + } + } + else { + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Type_0_has_no_call_signatures : + Diagnostics.Type_0_has_no_construct_signatures, + typeToString(apparentType), + ); + } + + let headMessage = isCall ? Diagnostics.This_expression_is_not_callable : Diagnostics.This_expression_is_not_constructable; + + // Diagnose get accessors incorrectly called as functions + if (isCallExpression(errorTarget.parent) && errorTarget.parent.arguments.length === 0) { + const { resolvedSymbol } = getNodeLinks(errorTarget); + if (resolvedSymbol && resolvedSymbol.flags & SymbolFlags.GetAccessor) { + headMessage = Diagnostics.This_expression_is_not_callable_because_it_is_a_get_accessor_Did_you_mean_to_use_it_without; + } + } + + return { + messageChain: chainDiagnosticMessages(errorInfo, headMessage), + relatedMessage: maybeMissingAwait ? Diagnostics.Did_you_forget_to_use_await : undefined, + }; + } + function invocationError(errorTarget: Node, apparentType: Type, kind: SignatureKind, relatedInformation?: DiagnosticRelatedInformation) { + const { messageChain, relatedMessage: relatedInfo } = invocationErrorDetails(errorTarget, apparentType, kind); + const diagnostic = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorTarget), errorTarget, messageChain); + if (relatedInfo) { + addRelatedInfo(diagnostic, createDiagnosticForNode(errorTarget, relatedInfo)); + } + if (isCallExpression(errorTarget.parent)) { + const { start, length } = getDiagnosticSpanForCallNode(errorTarget.parent); + diagnostic.start = start; + diagnostic.length = length; + } + diagnostics.add(diagnostic); + invocationErrorRecovery(apparentType, kind, relatedInformation ? addRelatedInfo(diagnostic, relatedInformation) : diagnostic); + } + + function invocationErrorRecovery(apparentType: Type, kind: SignatureKind, diagnostic: Diagnostic) { + if (!apparentType.symbol) { + return; + } + const importNode = getSymbolLinks(apparentType.symbol).originatingImport; + // Create a diagnostic on the originating import if possible onto which we can attach a quickfix + // An import call expression cannot be rewritten into another form to correct the error - the only solution is to use `.default` at the use-site + if (importNode && !isImportCall(importNode)) { + const sigs = getSignaturesOfType(getTypeOfSymbol(getSymbolLinks(apparentType.symbol).target!), kind); + if (!sigs || !sigs.length) return; + + addRelatedInfo(diagnostic, createDiagnosticForNode(importNode, Diagnostics.Type_originates_at_this_import_A_namespace_style_import_cannot_be_called_or_constructed_and_will_cause_a_failure_at_runtime_Consider_using_a_default_import_or_import_require_here_instead)); + } + } + + function resolveTaggedTemplateExpression(node: TaggedTemplateExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + const tagType = checkExpression(node.tag); + const apparentType = getApparentType(tagType); + + if (isErrorType(apparentType)) { + // Another error has already been reported + return resolveErrorCall(node); + } + + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; + + if (isUntypedFunctionCall(tagType, apparentType, callSignatures.length, numConstructSignatures)) { + return resolveUntypedCall(node); + } + + if (!callSignatures.length) { + if (isArrayLiteralExpression(node.parent)) { + const diagnostic = createDiagnosticForNode(node.tag, Diagnostics.It_is_likely_that_you_are_missing_a_comma_to_separate_these_two_template_expressions_They_form_a_tagged_template_expression_which_cannot_be_invoked); + diagnostics.add(diagnostic); + return resolveErrorCall(node); + } + + invocationError(node.tag, apparentType, SignatureKind.Call); + return resolveErrorCall(node); + } + + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + + /** + * Gets the localized diagnostic head message to use for errors when resolving a decorator as a call expression. + */ + function getDiagnosticHeadMessageForDecoratorResolution(node: Decorator) { + switch (node.parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + return Diagnostics.Unable_to_resolve_signature_of_class_decorator_when_called_as_an_expression; + + case SyntaxKind.Parameter: + return Diagnostics.Unable_to_resolve_signature_of_parameter_decorator_when_called_as_an_expression; + + case SyntaxKind.PropertyDeclaration: + return Diagnostics.Unable_to_resolve_signature_of_property_decorator_when_called_as_an_expression; + + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return Diagnostics.Unable_to_resolve_signature_of_method_decorator_when_called_as_an_expression; + + default: + return Debug.fail(); + } + } + + /** + * Resolves a decorator as if it were a call expression. + */ + function resolveDecorator(node: Decorator, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + const funcType = checkExpression(node.expression); + const apparentType = getApparentType(funcType); + if (isErrorType(apparentType)) { + return resolveErrorCall(node); + } + + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; + if (isUntypedFunctionCall(funcType, apparentType, callSignatures.length, numConstructSignatures)) { + return resolveUntypedCall(node); + } + + if (isPotentiallyUncalledDecorator(node, callSignatures) && !isParenthesizedExpression(node.expression)) { + const nodeStr = getTextOfNode(node.expression, /*includeTrivia*/ false); + error(node, Diagnostics._0_accepts_too_few_arguments_to_be_used_as_a_decorator_here_Did_you_mean_to_call_it_first_and_write_0, nodeStr); + return resolveErrorCall(node); + } + + const headMessage = getDiagnosticHeadMessageForDecoratorResolution(node); + if (!callSignatures.length) { + const errorDetails = invocationErrorDetails(node.expression, apparentType, SignatureKind.Call); + const messageChain = chainDiagnosticMessages(errorDetails.messageChain, headMessage); + const diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node.expression), node.expression, messageChain); + if (errorDetails.relatedMessage) { + addRelatedInfo(diag, createDiagnosticForNode(node.expression, errorDetails.relatedMessage)); + } + diagnostics.add(diag); + invocationErrorRecovery(apparentType, SignatureKind.Call, diag); + return resolveErrorCall(node); + } + + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None, headMessage); + } + + function createSignatureForJSXIntrinsic(node: JsxOpeningLikeElement, result: Type): Signature { + const namespace = getJsxNamespaceAt(node); + const exports = namespace && getExportsOfSymbol(namespace); + // We fake up a SFC signature for each intrinsic, however a more specific per-element signature drawn from the JSX declaration + // file would probably be preferable. + const typeSymbol = exports && getSymbol(exports, JsxNames.Element, SymbolFlags.Type); + const returnNode = typeSymbol && nodeBuilder.symbolToEntityName(typeSymbol, SymbolFlags.Type, node); + const declaration = factory.createFunctionTypeNode(/*typeParameters*/ undefined, [factory.createParameterDeclaration(/*modifiers*/ undefined, /*dotDotDotToken*/ undefined, "props", /*questionToken*/ undefined, nodeBuilder.typeToTypeNode(result, node))], returnNode ? factory.createTypeReferenceNode(returnNode, /*typeArguments*/ undefined) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword)); + const parameterSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "props" as __String); + parameterSymbol.links.type = result; + return createSignature( + declaration, + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [parameterSymbol], + typeSymbol ? getDeclaredTypeOfSymbol(typeSymbol) : errorType, + /*resolvedTypePredicate*/ undefined, + 1, + SignatureFlags.None, + ); + } + + function resolveJsxOpeningLikeElement(node: JsxOpeningLikeElement, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + if (isJsxIntrinsicTagName(node.tagName)) { + const result = getIntrinsicAttributesTypeFromJsxOpeningLikeElement(node); + const fakeSignature = createSignatureForJSXIntrinsic(node, result); + checkTypeAssignableToAndOptionallyElaborate(checkExpressionWithContextualType(node.attributes, getEffectiveFirstArgumentForJsxSignature(fakeSignature, node), /*inferenceContext*/ undefined, CheckMode.Normal), result, node.tagName, node.attributes); + if (length(node.typeArguments)) { + forEach(node.typeArguments, checkSourceElement); + diagnostics.add(createDiagnosticForNodeArray(getSourceFileOfNode(node), node.typeArguments!, Diagnostics.Expected_0_type_arguments_but_got_1, 0, length(node.typeArguments))); + } + return fakeSignature; + } + const exprTypes = checkExpression(node.tagName); + const apparentType = getApparentType(exprTypes); + if (isErrorType(apparentType)) { + return resolveErrorCall(node); + } + + const signatures = getUninstantiatedJsxSignaturesOfType(exprTypes, node); + if (isUntypedFunctionCall(exprTypes, apparentType, signatures.length, /*constructSignatures*/ 0)) { + return resolveUntypedCall(node); + } + + if (signatures.length === 0) { + // We found no signatures at all, which is an error + error(node.tagName, Diagnostics.JSX_element_type_0_does_not_have_any_construct_or_call_signatures, getTextOfNode(node.tagName)); + return resolveErrorCall(node); + } + + return resolveCall(node, signatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + + function resolveInstanceofExpression(node: InstanceofExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + // if rightType is an object type with a custom `[Symbol.hasInstance]` method, then it is potentially + // valid on the right-hand side of the `instanceof` operator. This allows normal `object` types to + // participate in `instanceof`, as per Step 2 of https://tc39.es/ecma262/#sec-instanceofoperator. + const rightType = checkExpression(node.right); + if (!isTypeAny(rightType)) { + const hasInstanceMethodType = getSymbolHasInstanceMethodOfObjectType(rightType); + if (hasInstanceMethodType) { + const apparentType = getApparentType(hasInstanceMethodType); + if (isErrorType(apparentType)) { + return resolveErrorCall(node); + } + + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const constructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct); + if (isUntypedFunctionCall(hasInstanceMethodType, apparentType, callSignatures.length, constructSignatures.length)) { + return resolveUntypedCall(node); + } + + if (callSignatures.length) { + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + } + // NOTE: do not raise error if right is unknown as related error was already reported + else if (!(typeHasCallOrConstructSignatures(rightType) || isTypeSubtypeOf(rightType, globalFunctionType))) { + error(node.right, Diagnostics.The_right_hand_side_of_an_instanceof_expression_must_be_either_of_type_any_a_class_function_or_other_type_assignable_to_the_Function_interface_type_or_an_object_type_with_a_Symbol_hasInstance_method); + return resolveErrorCall(node); + } + } + // fall back to a default signature + return anySignature; + } + + /** + * Sometimes, we have a decorator that could accept zero arguments, + * but is receiving too many arguments as part of the decorator invocation. + * In those cases, a user may have meant to *call* the expression before using it as a decorator. + */ + function isPotentiallyUncalledDecorator(decorator: Decorator, signatures: readonly Signature[]) { + return signatures.length && every(signatures, signature => + signature.minArgumentCount === 0 && + !signatureHasRestParameter(signature) && + signature.parameters.length < getDecoratorArgumentCount(decorator, signature)); + } + + function resolveSignature(node: CallLikeExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + switch (node.kind) { + case SyntaxKind.CallExpression: + return resolveCallExpression(node, candidatesOutArray, checkMode); + case SyntaxKind.NewExpression: + return resolveNewExpression(node, candidatesOutArray, checkMode); + case SyntaxKind.TaggedTemplateExpression: + return resolveTaggedTemplateExpression(node, candidatesOutArray, checkMode); + case SyntaxKind.Decorator: + return resolveDecorator(node, candidatesOutArray, checkMode); + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.JsxSelfClosingElement: + return resolveJsxOpeningLikeElement(node, candidatesOutArray, checkMode); + case SyntaxKind.BinaryExpression: + return resolveInstanceofExpression(node, candidatesOutArray, checkMode); + } + Debug.assertNever(node, "Branch in 'resolveSignature' should be unreachable."); + } + + /** + * Resolve a signature of a given call-like expression. + * @param node a call-like expression to try resolve a signature for + * @param candidatesOutArray an array of signature to be filled in by the function. It is passed by signature help in the language service; + * the function will fill it up with appropriate candidate signatures + * @return a signature of the call-like expression or undefined if one can't be found + */ + function getResolvedSignature(node: CallLikeExpression, candidatesOutArray?: Signature[] | undefined, checkMode?: CheckMode): Signature { + const links = getNodeLinks(node); + // If getResolvedSignature has already been called, we will have cached the resolvedSignature. + // However, it is possible that either candidatesOutArray was not passed in the first time, + // or that a different candidatesOutArray was passed in. Therefore, we need to redo the work + // to correctly fill the candidatesOutArray. + const cached = links.resolvedSignature; + if (cached && cached !== resolvingSignature && !candidatesOutArray) { + return cached; + } + const saveResolutionStart = resolutionStart; + if (!cached) { + // If we haven't already done so, temporarily reset the resolution stack. This allows us to + // handle "inverted" situations where, for example, an API client asks for the type of a symbol + // containined in a function call argument whose contextual type depends on the symbol itself + // through resolution of the containing function call. By resetting the resolution stack we'll + // retry the symbol type resolution with the resolvingSignature marker in place to suppress + // the contextual type circularity. + resolutionStart = resolutionTargets.length; + } + links.resolvedSignature = resolvingSignature; + let result = resolveSignature(node, candidatesOutArray, checkMode || CheckMode.Normal); + resolutionStart = saveResolutionStart; + // When CheckMode.SkipGenericFunctions is set we use resolvingSignature to indicate that call + // resolution should be deferred. + if (result !== resolvingSignature) { + // if the signature resolution originated on a node that itself depends on the contextual type + // then it's possible that the resolved signature might not be the same as the one that would be computed in source order + // since resolving such signature leads to resolving the potential outer signature, its arguments and thus the very same signature + // it's possible that this inner resolution sets the resolvedSignature first. + // In such a case we ignore the local result and reuse the correct one that was cached. + if (links.resolvedSignature !== resolvingSignature) { + result = links.resolvedSignature; + } + // If signature resolution originated in control flow type analysis (for example to compute the + // assigned type in a flow assignment) we don't cache the result as it may be based on temporary + // types from the control flow analysis. + links.resolvedSignature = flowLoopStart === flowLoopCount ? result : cached; + } + return result; + } + + /** + * Indicates whether a declaration can be treated as a constructor in a JavaScript + * file. + */ + function isJSConstructor(node: Node | undefined): node is FunctionDeclaration | FunctionExpression { + if (!node || !isInJSFile(node)) { + return false; + } + const func = isFunctionDeclaration(node) || isFunctionExpression(node) ? node : + (isVariableDeclaration(node) || isPropertyAssignment(node)) && node.initializer && isFunctionExpression(node.initializer) ? node.initializer : + undefined; + if (func) { + // If the node has a @class or @constructor tag, treat it like a constructor. + if (getJSDocClassTag(node)) return true; + + // If the node is a property of an object literal. + if (isPropertyAssignment(walkUpParenthesizedExpressions(func.parent))) return false; + + // If the symbol of the node has members, treat it like a constructor. + const symbol = getSymbolOfDeclaration(func); + return !!symbol?.members?.size; + } + return false; + } + + function mergeJSSymbols(target: Symbol, source: Symbol | undefined) { + if (source) { + const links = getSymbolLinks(source); + if (!links.inferredClassSymbol || !links.inferredClassSymbol.has(getSymbolId(target))) { + const inferred = isTransientSymbol(target) ? target : cloneSymbol(target); + inferred.exports = inferred.exports || createSymbolTable(); + inferred.members = inferred.members || createSymbolTable(); + inferred.flags |= source.flags & SymbolFlags.Class; + if (source.exports?.size) { + mergeSymbolTable(inferred.exports, source.exports); + } + if (source.members?.size) { + mergeSymbolTable(inferred.members, source.members); + } + (links.inferredClassSymbol || (links.inferredClassSymbol = new Map())).set(getSymbolId(inferred), inferred); + return inferred; + } + return links.inferredClassSymbol.get(getSymbolId(target)); + } + } + + function getAssignedClassSymbol(decl: Declaration): Symbol | undefined { + const assignmentSymbol = decl && getSymbolOfExpando(decl, /*allowDeclaration*/ true); + const prototype = assignmentSymbol?.exports?.get("prototype" as __String); + const init = prototype?.valueDeclaration && getAssignedJSPrototype(prototype.valueDeclaration); + return init ? getSymbolOfDeclaration(init) : undefined; + } + + function getSymbolOfExpando(node: Node, allowDeclaration: boolean): Symbol | undefined { + if (!node.parent) { + return undefined; + } + let name: Expression | BindingName | undefined; + let decl: Node | undefined; + if (isVariableDeclaration(node.parent) && node.parent.initializer === node) { + if (!isInJSFile(node) && !(isVarConstLike(node.parent) && isFunctionLikeDeclaration(node))) { + return undefined; + } + name = node.parent.name; + decl = node.parent; + } + else if (isBinaryExpression(node.parent)) { + const parentNode = node.parent; + const parentNodeOperator = node.parent.operatorToken.kind; + if (parentNodeOperator === SyntaxKind.EqualsToken && (allowDeclaration || parentNode.right === node)) { + name = parentNode.left; + decl = name; + } + else if (parentNodeOperator === SyntaxKind.BarBarToken || parentNodeOperator === SyntaxKind.QuestionQuestionToken) { + if (isVariableDeclaration(parentNode.parent) && parentNode.parent.initializer === parentNode) { + name = parentNode.parent.name; + decl = parentNode.parent; + } + else if (isBinaryExpression(parentNode.parent) && parentNode.parent.operatorToken.kind === SyntaxKind.EqualsToken && (allowDeclaration || parentNode.parent.right === parentNode)) { + name = parentNode.parent.left; + decl = name; + } + + if (!name || !isBindableStaticNameExpression(name) || !isSameEntityName(name, parentNode.left)) { + return undefined; + } + } + } + else if (allowDeclaration && isFunctionDeclaration(node)) { + name = node.name; + decl = node; + } + + if (!decl || !name || (!allowDeclaration && !getExpandoInitializer(node, isPrototypeAccess(name)))) { + return undefined; + } + return getSymbolOfNode(decl); + } + + function getAssignedJSPrototype(node: Node) { + if (!node.parent) { + return false; + } + let parent: Node = node.parent; + while (parent && parent.kind === SyntaxKind.PropertyAccessExpression) { + parent = parent.parent; + } + if (parent && isBinaryExpression(parent) && isPrototypeAccess(parent.left) && parent.operatorToken.kind === SyntaxKind.EqualsToken) { + const right = getInitializerOfBinaryExpression(parent); + return isObjectLiteralExpression(right) && right; + } + } + + /** + * Syntactically and semantically checks a call or new expression. + * @param node The call/new expression to be checked. + * @returns On success, the expression's signature's return type. On failure, anyType. + */ + function checkCallExpression(node: CallExpression | NewExpression, checkMode?: CheckMode): Type { + checkGrammarTypeArguments(node, node.typeArguments); + + const signature = getResolvedSignature(node, /*candidatesOutArray*/ undefined, checkMode); + if (signature === resolvingSignature) { + // CheckMode.SkipGenericFunctions is enabled and this is a call to a generic function that + // returns a function type. We defer checking and return silentNeverType. + return silentNeverType; + } + + checkDeprecatedSignature(signature, node); + + if (node.expression.kind === SyntaxKind.SuperKeyword) { + return voidType; + } + + if (node.kind === SyntaxKind.NewExpression) { + const declaration = signature.declaration; + + if ( + declaration && + declaration.kind !== SyntaxKind.Constructor && + declaration.kind !== SyntaxKind.ConstructSignature && + declaration.kind !== SyntaxKind.ConstructorType && + !(isJSDocSignature(declaration) && getJSDocRoot(declaration)?.parent?.kind === SyntaxKind.Constructor) && + !isJSDocConstructSignature(declaration) && + !isJSConstructor(declaration) + ) { + // When resolved signature is a call signature (and not a construct signature) the result type is any + if (noImplicitAny) { + error(node, Diagnostics.new_expression_whose_target_lacks_a_construct_signature_implicitly_has_an_any_type); + } + return anyType; + } + } + + // In JavaScript files, calls to any identifier 'require' are treated as external module imports + if (isInJSFile(node) && isCommonJsRequire(node)) { + return resolveExternalModuleTypeByLiteral(node.arguments![0] as StringLiteral); + } + + const returnType = getReturnTypeOfSignature(signature); + // Treat any call to the global 'Symbol' function that is part of a const variable or readonly property + // as a fresh unique symbol literal type. + if (returnType.flags & TypeFlags.ESSymbolLike && isSymbolOrSymbolForCall(node)) { + return getESSymbolLikeTypeForNode(walkUpParenthesizedExpressions(node.parent)); + } + if ( + node.kind === SyntaxKind.CallExpression && !node.questionDotToken && node.parent.kind === SyntaxKind.ExpressionStatement && + returnType.flags & TypeFlags.Void && getTypePredicateOfSignature(signature) + ) { + if (!isDottedName(node.expression)) { + error(node.expression, Diagnostics.Assertions_require_the_call_target_to_be_an_identifier_or_qualified_name); + } + else if (!getEffectsSignature(node)) { + const diagnostic = error(node.expression, Diagnostics.Assertions_require_every_name_in_the_call_target_to_be_declared_with_an_explicit_type_annotation); + getTypeOfDottedName(node.expression, diagnostic); + } + } + + if (isInJSFile(node)) { + const jsSymbol = getSymbolOfExpando(node, /*allowDeclaration*/ false); + if (jsSymbol?.exports?.size) { + const jsAssignmentType = createAnonymousType(jsSymbol, jsSymbol.exports, emptyArray, emptyArray, emptyArray); + jsAssignmentType.objectFlags |= ObjectFlags.JSLiteral; + return getIntersectionType([returnType, jsAssignmentType]); + } + } + + return returnType; + } + + function checkDeprecatedSignature(signature: Signature, node: CallLikeExpression) { + if (signature.flags & SignatureFlags.IsSignatureCandidateForOverloadFailure) return; + if (signature.declaration && signature.declaration.flags & NodeFlags.Deprecated) { + const suggestionNode = getDeprecatedSuggestionNode(node); + const name = tryGetPropertyAccessOrIdentifierToString(getInvokedExpression(node)); + addDeprecatedSuggestionWithSignature(suggestionNode, signature.declaration, name, signatureToString(signature)); + } + } + + function getDeprecatedSuggestionNode(node: Node): Node { + node = skipParentheses(node); + switch (node.kind) { + case SyntaxKind.CallExpression: + case SyntaxKind.Decorator: + case SyntaxKind.NewExpression: + return getDeprecatedSuggestionNode((node as Decorator | CallExpression | NewExpression).expression); + case SyntaxKind.TaggedTemplateExpression: + return getDeprecatedSuggestionNode((node as TaggedTemplateExpression).tag); + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.JsxSelfClosingElement: + return getDeprecatedSuggestionNode((node as JsxOpeningLikeElement).tagName); + case SyntaxKind.ElementAccessExpression: + return (node as ElementAccessExpression).argumentExpression; + case SyntaxKind.PropertyAccessExpression: + return (node as PropertyAccessExpression).name; + case SyntaxKind.TypeReference: + const typeReference = node as TypeReferenceNode; + return isQualifiedName(typeReference.typeName) ? typeReference.typeName.right : typeReference; + default: + return node; + } + } + + function isSymbolOrSymbolForCall(node: Node) { + if (!isCallExpression(node)) return false; + let left = node.expression; + if (isPropertyAccessExpression(left) && left.name.escapedText === "for") { + left = left.expression; + } + if (!isIdentifier(left) || left.escapedText !== "Symbol") { + return false; + } + + // make sure `Symbol` is the global symbol + const globalESSymbol = getGlobalESSymbolConstructorSymbol(/*reportErrors*/ false); + if (!globalESSymbol) { + return false; + } + + return globalESSymbol === resolveName(left, "Symbol" as __String, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + } + + function checkImportCallExpression(node: ImportCall): Type { + // Check grammar of dynamic import + checkGrammarImportCallExpression(node); + + if (node.arguments.length === 0) { + return createPromiseReturnType(node, anyType); + } + + const specifier = node.arguments[0]; + const specifierType = checkExpressionCached(specifier); + const optionsType = node.arguments.length > 1 ? checkExpressionCached(node.arguments[1]) : undefined; + // Even though multiple arguments is grammatically incorrect, type-check extra arguments for completion + for (let i = 2; i < node.arguments.length; ++i) { + checkExpressionCached(node.arguments[i]); + } + + if (specifierType.flags & TypeFlags.Undefined || specifierType.flags & TypeFlags.Null || !isTypeAssignableTo(specifierType, stringType)) { + error(specifier, Diagnostics.Dynamic_import_s_specifier_must_be_of_type_string_but_here_has_type_0, typeToString(specifierType)); + } + + if (optionsType) { + const importCallOptionsType = getGlobalImportCallOptionsType(/*reportErrors*/ true); + if (importCallOptionsType !== emptyObjectType) { + checkTypeAssignableTo(optionsType, getNullableType(importCallOptionsType, TypeFlags.Undefined), node.arguments[1]); + } + } + + // resolveExternalModuleName will return undefined if the moduleReferenceExpression is not a string literal + const moduleSymbol = resolveExternalModuleName(node, specifier); + if (moduleSymbol) { + const esModuleSymbol = resolveESModuleSymbol(moduleSymbol, specifier, /*dontResolveAlias*/ true, /*suppressInteropError*/ false); + if (esModuleSymbol) { + return createPromiseReturnType( + node, + getTypeWithSyntheticDefaultOnly(getTypeOfSymbol(esModuleSymbol), esModuleSymbol, moduleSymbol, specifier) || + getTypeWithSyntheticDefaultImportType(getTypeOfSymbol(esModuleSymbol), esModuleSymbol, moduleSymbol, specifier), + ); + } + } + return createPromiseReturnType(node, anyType); + } + + function createDefaultPropertyWrapperForModule(symbol: Symbol, originalSymbol: Symbol | undefined, anonymousSymbol?: Symbol | undefined) { + const memberTable = createSymbolTable(); + const newSymbol = createSymbol(SymbolFlags.Alias, InternalSymbolName.Default); + newSymbol.parent = originalSymbol; + newSymbol.links.nameType = getStringLiteralType("default"); + newSymbol.links.aliasTarget = resolveSymbol(symbol); + memberTable.set(InternalSymbolName.Default, newSymbol); + return createAnonymousType(anonymousSymbol, memberTable, emptyArray, emptyArray, emptyArray); + } + + function getTypeWithSyntheticDefaultOnly(type: Type, symbol: Symbol, originalSymbol: Symbol, moduleSpecifier: Expression) { + const hasDefaultOnly = isOnlyImportedAsDefault(moduleSpecifier); + if (hasDefaultOnly && type && !isErrorType(type)) { + const synthType = type as SyntheticDefaultModuleType; + if (!synthType.defaultOnlyType) { + const type = createDefaultPropertyWrapperForModule(symbol, originalSymbol); + synthType.defaultOnlyType = type; + } + return synthType.defaultOnlyType; + } + return undefined; + } + + function getTypeWithSyntheticDefaultImportType(type: Type, symbol: Symbol, originalSymbol: Symbol, moduleSpecifier: Expression): Type { + if (allowSyntheticDefaultImports && type && !isErrorType(type)) { + const synthType = type as SyntheticDefaultModuleType; + if (!synthType.syntheticType) { + const file = originalSymbol.declarations?.find(isSourceFile); + const hasSyntheticDefault = canHaveSyntheticDefault(file, originalSymbol, /*dontResolveAlias*/ false, moduleSpecifier); + if (hasSyntheticDefault) { + const anonymousSymbol = createSymbol(SymbolFlags.TypeLiteral, InternalSymbolName.Type); + const defaultContainingObject = createDefaultPropertyWrapperForModule(symbol, originalSymbol, anonymousSymbol); + anonymousSymbol.links.type = defaultContainingObject; + synthType.syntheticType = isValidSpreadType(type) ? getSpreadType(type, defaultContainingObject, anonymousSymbol, /*objectFlags*/ 0, /*readonly*/ false) : defaultContainingObject; + } + else { + synthType.syntheticType = type; + } + } + return synthType.syntheticType; + } + return type; + } + + function isCommonJsRequire(node: Node): boolean { + if (!isRequireCall(node, /*requireStringLiteralLikeArgument*/ true)) { + return false; + } + + // Make sure require is not a local function + if (!isIdentifier(node.expression)) return Debug.fail(); + const resolvedRequire = resolveName(node.expression, node.expression.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true)!; // TODO: GH#18217 + if (resolvedRequire === requireSymbol) { + return true; + } + // project includes symbol named 'require' - make sure that it is ambient and local non-alias + if (resolvedRequire.flags & SymbolFlags.Alias) { + return false; + } + + const targetDeclarationKind = resolvedRequire.flags & SymbolFlags.Function + ? SyntaxKind.FunctionDeclaration + : resolvedRequire.flags & SymbolFlags.Variable + ? SyntaxKind.VariableDeclaration + : SyntaxKind.Unknown; + if (targetDeclarationKind !== SyntaxKind.Unknown) { + const decl = getDeclarationOfKind(resolvedRequire, targetDeclarationKind)!; + // function/variable declaration should be ambient + return !!decl && !!(decl.flags & NodeFlags.Ambient); + } + return false; + } + + function checkTaggedTemplateExpression(node: TaggedTemplateExpression): Type { + if (!checkGrammarTaggedTemplateChain(node)) checkGrammarTypeArguments(node, node.typeArguments); + if (languageVersion < LanguageFeatureMinimumTarget.TaggedTemplates) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.MakeTemplateObject); + } + const signature = getResolvedSignature(node); + checkDeprecatedSignature(signature, node); + return getReturnTypeOfSignature(signature); + } + + function checkAssertion(node: AssertionExpression, checkMode: CheckMode | undefined) { + if (node.kind === SyntaxKind.TypeAssertionExpression) { + const file = getSourceFileOfNode(node); + if (file && fileExtensionIsOneOf(file.fileName, [Extension.Cts, Extension.Mts])) { + grammarErrorOnNode(node, Diagnostics.This_syntax_is_reserved_in_files_with_the_mts_or_cts_extension_Use_an_as_expression_instead); + } + } + return checkAssertionWorker(node, checkMode); + } + + function isValidConstAssertionArgument(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.StringLiteral: + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.NumericLiteral: + case SyntaxKind.BigIntLiteral: + case SyntaxKind.TrueKeyword: + case SyntaxKind.FalseKeyword: + case SyntaxKind.ArrayLiteralExpression: + case SyntaxKind.ObjectLiteralExpression: + case SyntaxKind.TemplateExpression: + return true; + case SyntaxKind.ParenthesizedExpression: + return isValidConstAssertionArgument((node as ParenthesizedExpression).expression); + case SyntaxKind.PrefixUnaryExpression: + const op = (node as PrefixUnaryExpression).operator; + const arg = (node as PrefixUnaryExpression).operand; + return op === SyntaxKind.MinusToken && (arg.kind === SyntaxKind.NumericLiteral || arg.kind === SyntaxKind.BigIntLiteral) || + op === SyntaxKind.PlusToken && arg.kind === SyntaxKind.NumericLiteral; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + const expr = skipParentheses((node as PropertyAccessExpression | ElementAccessExpression).expression); + const symbol = isEntityNameExpression(expr) ? resolveEntityName(expr, SymbolFlags.Value, /*ignoreErrors*/ true) : undefined; + return !!(symbol && symbol.flags & SymbolFlags.Enum); + } + return false; + } + + function checkAssertionWorker(node: JSDocTypeAssertion | AssertionExpression, checkMode: CheckMode | undefined) { + const { type, expression } = getAssertionTypeAndExpression(node); + const exprType = checkExpression(expression, checkMode); + if (isConstTypeReference(type)) { + if (!isValidConstAssertionArgument(expression)) { + error(expression, Diagnostics.A_const_assertions_can_only_be_applied_to_references_to_enum_members_or_string_number_boolean_array_or_object_literals); + } + return getRegularTypeOfLiteralType(exprType); + } + const links = getNodeLinks(node); + links.assertionExpressionType = exprType; + checkSourceElement(type); + checkNodeDeferred(node); + return getTypeFromTypeNode(type); + } + + function getAssertionTypeAndExpression(node: JSDocTypeAssertion | AssertionExpression) { + let type: TypeNode; + let expression: Expression; + switch (node.kind) { + case SyntaxKind.AsExpression: + case SyntaxKind.TypeAssertionExpression: + type = node.type; + expression = node.expression; + break; + case SyntaxKind.ParenthesizedExpression: + type = getJSDocTypeAssertionType(node); + expression = node.expression; + break; + } + + return { type, expression }; + } + + function checkAssertionDeferred(node: JSDocTypeAssertion | AssertionExpression) { + const { type } = getAssertionTypeAndExpression(node); + const errNode = isParenthesizedExpression(node) ? type : node; + const links = getNodeLinks(node); + Debug.assertIsDefined(links.assertionExpressionType); + const exprType = getRegularTypeOfObjectLiteral(getBaseTypeOfLiteralType(links.assertionExpressionType)); + const targetType = getTypeFromTypeNode(type); + if (!isErrorType(targetType)) { + addLazyDiagnostic(() => { + const widenedType = getWidenedType(exprType); + if (!isTypeComparableTo(targetType, widenedType)) { + checkTypeComparableTo(exprType, targetType, errNode, Diagnostics.Conversion_of_type_0_to_type_1_may_be_a_mistake_because_neither_type_sufficiently_overlaps_with_the_other_If_this_was_intentional_convert_the_expression_to_unknown_first); + } + }); + } + } + + function checkNonNullChain(node: NonNullChain) { + const leftType = checkExpression(node.expression); + const nonOptionalType = getOptionalExpressionType(leftType, node.expression); + return propagateOptionalTypeMarker(getNonNullableType(nonOptionalType), node, nonOptionalType !== leftType); + } + + function checkNonNullAssertion(node: NonNullExpression) { + return node.flags & NodeFlags.OptionalChain ? checkNonNullChain(node as NonNullChain) : + getNonNullableType(checkExpression(node.expression)); + } + + function checkExpressionWithTypeArguments(node: ExpressionWithTypeArguments | TypeQueryNode) { + checkGrammarExpressionWithTypeArguments(node); + forEach(node.typeArguments, checkSourceElement); + if (node.kind === SyntaxKind.ExpressionWithTypeArguments) { + const parent = walkUpParenthesizedExpressions(node.parent); + if (parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.InstanceOfKeyword && isNodeDescendantOf(node, (parent as BinaryExpression).right)) { + error(node, Diagnostics.The_right_hand_side_of_an_instanceof_expression_must_not_be_an_instantiation_expression); + } + } + const exprType = node.kind === SyntaxKind.ExpressionWithTypeArguments ? checkExpression(node.expression) : + isThisIdentifier(node.exprName) ? checkThisExpression(node.exprName) : + checkExpression(node.exprName); + return getInstantiationExpressionType(exprType, node); + } + + function getInstantiationExpressionType(exprType: Type, node: NodeWithTypeArguments) { + const typeArguments = node.typeArguments; + if (exprType === silentNeverType || isErrorType(exprType) || !some(typeArguments)) { + return exprType; + } + let hasSomeApplicableSignature = false; + let nonApplicableType: Type | undefined; + const result = getInstantiatedType(exprType); + const errorType = hasSomeApplicableSignature ? nonApplicableType : exprType; + if (errorType) { + diagnostics.add(createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Type_0_has_no_signatures_for_which_the_type_argument_list_is_applicable, typeToString(errorType))); + } + return result; + + function getInstantiatedType(type: Type): Type { + let hasSignatures = false; + let hasApplicableSignature = false; + const result = getInstantiatedTypePart(type); + hasSomeApplicableSignature ||= hasApplicableSignature; + if (hasSignatures && !hasApplicableSignature) { + nonApplicableType ??= type; + } + return result; + + function getInstantiatedTypePart(type: Type): Type { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + const callSignatures = getInstantiatedSignatures(resolved.callSignatures); + const constructSignatures = getInstantiatedSignatures(resolved.constructSignatures); + hasSignatures ||= resolved.callSignatures.length !== 0 || resolved.constructSignatures.length !== 0; + hasApplicableSignature ||= callSignatures.length !== 0 || constructSignatures.length !== 0; + if (callSignatures !== resolved.callSignatures || constructSignatures !== resolved.constructSignatures) { + const result = createAnonymousType(createSymbol(SymbolFlags.None, InternalSymbolName.InstantiationExpression), resolved.members, callSignatures, constructSignatures, resolved.indexInfos) as ResolvedType & InstantiationExpressionType; + result.objectFlags |= ObjectFlags.InstantiationExpressionType; + result.node = node; + return result; + } + } + else if (type.flags & TypeFlags.InstantiableNonPrimitive) { + const constraint = getBaseConstraintOfType(type); + if (constraint) { + const instantiated = getInstantiatedTypePart(constraint); + if (instantiated !== constraint) { + return instantiated; + } + } + } + else if (type.flags & TypeFlags.Union) { + return mapType(type, getInstantiatedType); + } + else if (type.flags & TypeFlags.Intersection) { + return getIntersectionType(sameMap((type as IntersectionType).types, getInstantiatedTypePart)); + } + return type; + } + } + + function getInstantiatedSignatures(signatures: readonly Signature[]) { + const applicableSignatures = filter(signatures, sig => !!sig.typeParameters && hasCorrectTypeArgumentArity(sig, typeArguments)); + return sameMap(applicableSignatures, sig => { + const typeArgumentTypes = checkTypeArguments(sig, typeArguments!, /*reportErrors*/ true); + return typeArgumentTypes ? getSignatureInstantiation(sig, typeArgumentTypes, isInJSFile(sig.declaration)) : sig; + }); + } + } + + function checkSatisfiesExpression(node: SatisfiesExpression) { + checkSourceElement(node.type); + return checkSatisfiesExpressionWorker(node.expression, node.type); + } + + function checkSatisfiesExpressionWorker(expression: Expression, target: TypeNode, checkMode?: CheckMode) { + const exprType = checkExpression(expression, checkMode); + const targetType = getTypeFromTypeNode(target); + if (isErrorType(targetType)) { + return targetType; + } + const errorNode = findAncestor(target.parent, n => n.kind === SyntaxKind.SatisfiesExpression || n.kind === SyntaxKind.JSDocSatisfiesTag); + checkTypeAssignableToAndOptionallyElaborate(exprType, targetType, errorNode, expression, Diagnostics.Type_0_does_not_satisfy_the_expected_type_1); + return exprType; + } + + function checkMetaProperty(node: MetaProperty): Type { + checkGrammarMetaProperty(node); + + if (node.keywordToken === SyntaxKind.NewKeyword) { + return checkNewTargetMetaProperty(node); + } + + if (node.keywordToken === SyntaxKind.ImportKeyword) { + return checkImportMetaProperty(node); + } + + return Debug.assertNever(node.keywordToken); + } + + function checkMetaPropertyKeyword(node: MetaProperty): Type { + switch (node.keywordToken) { + case SyntaxKind.ImportKeyword: + return getGlobalImportMetaExpressionType(); + case SyntaxKind.NewKeyword: + const type = checkNewTargetMetaProperty(node); + return isErrorType(type) ? errorType : createNewTargetExpressionType(type); + default: + Debug.assertNever(node.keywordToken); + } + } + + function checkNewTargetMetaProperty(node: MetaProperty) { + const container = getNewTargetContainer(node); + if (!container) { + error(node, Diagnostics.Meta_property_0_is_only_allowed_in_the_body_of_a_function_declaration_function_expression_or_constructor, "new.target"); + return errorType; + } + else if (container.kind === SyntaxKind.Constructor) { + const symbol = getSymbolOfDeclaration(container.parent); + return getTypeOfSymbol(symbol); + } + else { + const symbol = getSymbolOfDeclaration(container); + return getTypeOfSymbol(symbol); + } + } + + function checkImportMetaProperty(node: MetaProperty) { + if (moduleKind === ModuleKind.Node16 || moduleKind === ModuleKind.NodeNext) { + if (getSourceFileOfNode(node).impliedNodeFormat !== ModuleKind.ESNext) { + error(node, Diagnostics.The_import_meta_meta_property_is_not_allowed_in_files_which_will_build_into_CommonJS_output); + } + } + else if (moduleKind < ModuleKind.ES2020 && moduleKind !== ModuleKind.System) { + error(node, Diagnostics.The_import_meta_meta_property_is_only_allowed_when_the_module_option_is_es2020_es2022_esnext_system_node16_or_nodenext); + } + const file = getSourceFileOfNode(node); + Debug.assert(!!(file.flags & NodeFlags.PossiblyContainsImportMeta), "Containing file is missing import meta node flag."); + return node.name.escapedText === "meta" ? getGlobalImportMetaType() : errorType; + } + + function getTypeOfParameter(symbol: Symbol) { + const declaration = symbol.valueDeclaration; + return addOptionality( + getTypeOfSymbol(symbol), + /*isProperty*/ false, + /*isOptional*/ !!declaration && (hasInitializer(declaration) || isOptionalDeclaration(declaration)), + ); + } + + function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember): __String; + function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember | undefined, index: number, restParameterName?: __String): __String; + function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember | undefined, index?: number, restParameterName = "arg" as __String) { + if (!d) { + return `${restParameterName}_${index}` as __String; + } + Debug.assert(isIdentifier(d.name)); // Parameter declarations could be binding patterns, but we only allow identifier names + return d.name.escapedText; + } + + function getParameterNameAtPosition(signature: Signature, pos: number, overrideRestType?: Type) { + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + return signature.parameters[pos].escapedName; + } + const restParameter = signature.parameters[paramCount] || unknownSymbol; + const restType = overrideRestType || getTypeOfSymbol(restParameter); + if (isTupleType(restType)) { + const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; + const index = pos - paramCount; + return getTupleElementLabel(associatedNames?.[index], index, restParameter.escapedName); + } + return restParameter.escapedName; + } + + function getParameterIdentifierInfoAtPosition(signature: Signature, pos: number): { parameter: Identifier; parameterName: __String; isRestParameter: boolean; } | undefined { + if (signature.declaration?.kind === SyntaxKind.JSDocFunctionType) { + return undefined; + } + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + const param = signature.parameters[pos]; + const paramIdent = getParameterDeclarationIdentifier(param); + return paramIdent ? { + parameter: paramIdent, + parameterName: param.escapedName, + isRestParameter: false, + } : undefined; + } + + const restParameter = signature.parameters[paramCount] || unknownSymbol; + const restIdent = getParameterDeclarationIdentifier(restParameter); + if (!restIdent) { + return undefined; + } + + const restType = getTypeOfSymbol(restParameter); + if (isTupleType(restType)) { + const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; + const index = pos - paramCount; + const associatedName = associatedNames?.[index]; + const isRestTupleElement = !!associatedName?.dotDotDotToken; + + if (associatedName) { + Debug.assert(isIdentifier(associatedName.name)); + return { parameter: associatedName.name, parameterName: associatedName.name.escapedText, isRestParameter: isRestTupleElement }; + } + + return undefined; + } + + if (pos === paramCount) { + return { parameter: restIdent, parameterName: restParameter.escapedName, isRestParameter: true }; + } + return undefined; + } + + function getParameterDeclarationIdentifier(symbol: Symbol) { + return symbol.valueDeclaration && isParameter(symbol.valueDeclaration) && isIdentifier(symbol.valueDeclaration.name) && symbol.valueDeclaration.name; + } + function isValidDeclarationForTupleLabel(d: Declaration): d is NamedTupleMember | (ParameterDeclaration & { name: Identifier; }) { + return d.kind === SyntaxKind.NamedTupleMember || (isParameter(d) && d.name && isIdentifier(d.name)); + } + + function getNameableDeclarationAtPosition(signature: Signature, pos: number) { + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + const decl = signature.parameters[pos].valueDeclaration; + return decl && isValidDeclarationForTupleLabel(decl) ? decl : undefined; + } + const restParameter = signature.parameters[paramCount] || unknownSymbol; + const restType = getTypeOfSymbol(restParameter); + if (isTupleType(restType)) { + const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; + const index = pos - paramCount; + return associatedNames && associatedNames[index]; + } + return restParameter.valueDeclaration && isValidDeclarationForTupleLabel(restParameter.valueDeclaration) ? restParameter.valueDeclaration : undefined; + } + + function getTypeAtPosition(signature: Signature, pos: number): Type { + return tryGetTypeAtPosition(signature, pos) || anyType; + } + + function tryGetTypeAtPosition(signature: Signature, pos: number): Type | undefined { + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + return getTypeOfParameter(signature.parameters[pos]); + } + if (signatureHasRestParameter(signature)) { + // We want to return the value undefined for an out of bounds parameter position, + // so we need to check bounds here before calling getIndexedAccessType (which + // otherwise would return the type 'undefined'). + const restType = getTypeOfSymbol(signature.parameters[paramCount]); + const index = pos - paramCount; + if (!isTupleType(restType) || restType.target.combinedFlags & ElementFlags.Variable || index < restType.target.fixedLength) { + return getIndexedAccessType(restType, getNumberLiteralType(index)); + } + } + return undefined; + } + + function getRestTypeAtPosition(source: Signature, pos: number, readonly?: boolean): Type { + const parameterCount = getParameterCount(source); + const minArgumentCount = getMinArgumentCount(source); + const restType = getEffectiveRestType(source); + if (restType && pos >= parameterCount - 1) { + return pos === parameterCount - 1 ? restType : createArrayType(getIndexedAccessType(restType, numberType)); + } + const types = []; + const flags = []; + const names = []; + for (let i = pos; i < parameterCount; i++) { + if (!restType || i < parameterCount - 1) { + types.push(getTypeAtPosition(source, i)); + flags.push(i < minArgumentCount ? ElementFlags.Required : ElementFlags.Optional); + } + else { + types.push(restType); + flags.push(ElementFlags.Variadic); + } + names.push(getNameableDeclarationAtPosition(source, i)); + } + return createTupleType(types, flags, readonly, names); + } + + // Return the rest type at the given position, transforming `any[]` into just `any`. We do this because + // in signatures we want `any[]` in a rest position to be compatible with anything, but `any[]` isn't + // assignable to tuple types with required elements. + function getRestOrAnyTypeAtPosition(source: Signature, pos: number): Type { + const restType = getRestTypeAtPosition(source, pos); + const elementType = restType && getElementTypeOfArrayType(restType); + return elementType && isTypeAny(elementType) ? anyType : restType; + } + + // Return the number of parameters in a signature. The rest parameter, if present, counts as one + // parameter. For example, the parameter count of (x: number, y: number, ...z: string[]) is 3 and + // the parameter count of (x: number, ...args: [number, ...string[], boolean])) is also 3. In the + // latter example, the effective rest type is [...string[], boolean]. + function getParameterCount(signature: Signature) { + const length = signature.parameters.length; + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[length - 1]); + if (isTupleType(restType)) { + return length + restType.target.fixedLength - (restType.target.combinedFlags & ElementFlags.Variable ? 0 : 1); + } + } + return length; + } + + function getMinArgumentCount(signature: Signature, flags?: MinArgumentCountFlags) { + const strongArityForUntypedJS = flags! & MinArgumentCountFlags.StrongArityForUntypedJS; + const voidIsNonOptional = flags! & MinArgumentCountFlags.VoidIsNonOptional; + if (voidIsNonOptional || signature.resolvedMinArgumentCount === undefined) { + let minArgumentCount: number | undefined; + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + if (isTupleType(restType)) { + const firstOptionalIndex = findIndex(restType.target.elementFlags, f => !(f & ElementFlags.Required)); + const requiredCount = firstOptionalIndex < 0 ? restType.target.fixedLength : firstOptionalIndex; + if (requiredCount > 0) { + minArgumentCount = signature.parameters.length - 1 + requiredCount; + } + } + } + if (minArgumentCount === undefined) { + if (!strongArityForUntypedJS && signature.flags & SignatureFlags.IsUntypedSignatureInJSFile) { + return 0; + } + minArgumentCount = signature.minArgumentCount; + } + if (voidIsNonOptional) { + return minArgumentCount; + } + for (let i = minArgumentCount - 1; i >= 0; i--) { + const type = getTypeAtPosition(signature, i); + if (filterType(type, acceptsVoid).flags & TypeFlags.Never) { + break; + } + minArgumentCount = i; + } + signature.resolvedMinArgumentCount = minArgumentCount; + } + return signature.resolvedMinArgumentCount; + } + + function hasEffectiveRestParameter(signature: Signature) { + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + return !isTupleType(restType) || !!(restType.target.combinedFlags & ElementFlags.Variable); + } + return false; + } + + function getEffectiveRestType(signature: Signature) { + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + if (!isTupleType(restType)) { + return isTypeAny(restType) ? anyArrayType : restType; + } + if (restType.target.combinedFlags & ElementFlags.Variable) { + return sliceTupleType(restType, restType.target.fixedLength); + } + } + return undefined; + } + + function getNonArrayRestType(signature: Signature) { + const restType = getEffectiveRestType(signature); + return restType && !isArrayType(restType) && !isTypeAny(restType) ? restType : undefined; + } + + function getTypeOfFirstParameterOfSignature(signature: Signature) { + return getTypeOfFirstParameterOfSignatureWithFallback(signature, neverType); + } + + function getTypeOfFirstParameterOfSignatureWithFallback(signature: Signature, fallbackType: Type) { + return signature.parameters.length > 0 ? getTypeAtPosition(signature, 0) : fallbackType; + } + + function inferFromAnnotatedParameters(signature: Signature, context: Signature, inferenceContext: InferenceContext) { + const len = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + for (let i = 0; i < len; i++) { + const declaration = signature.parameters[i].valueDeclaration as ParameterDeclaration; + const typeNode = getEffectiveTypeAnnotationNode(declaration); + if (typeNode) { + const source = addOptionality(getTypeFromTypeNode(typeNode), /*isProperty*/ false, isOptionalDeclaration(declaration)); + const target = getTypeAtPosition(context, i); + inferTypes(inferenceContext.inferences, source, target); + } + } + } + + function assignContextualParameterTypes(signature: Signature, context: Signature) { + if (context.typeParameters) { + if (!signature.typeParameters) { + signature.typeParameters = context.typeParameters; + } + else { + return; // This signature has already has a contextual inference performed and cached on it! + } + } + if (context.thisParameter) { + const parameter = signature.thisParameter; + if (!parameter || parameter.valueDeclaration && !(parameter.valueDeclaration as ParameterDeclaration).type) { + if (!parameter) { + signature.thisParameter = createSymbolWithType(context.thisParameter, /*type*/ undefined); + } + assignParameterType(signature.thisParameter!, getTypeOfSymbol(context.thisParameter)); + } + } + const len = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + for (let i = 0; i < len; i++) { + const parameter = signature.parameters[i]; + const declaration = parameter.valueDeclaration as ParameterDeclaration; + if (!getEffectiveTypeAnnotationNode(declaration)) { + let type = tryGetTypeAtPosition(context, i); + if (type && declaration.initializer) { + let initializerType = checkDeclarationInitializer(declaration, CheckMode.Normal); + if (!isTypeAssignableTo(initializerType, type) && isTypeAssignableTo(type, initializerType = widenTypeInferredFromInitializer(declaration, initializerType))) { + type = initializerType; + } + } + assignParameterType(parameter, type); + } + } + if (signatureHasRestParameter(signature)) { + // parameter might be a transient symbol generated by use of `arguments` in the function body. + const parameter = last(signature.parameters); + if ( + parameter.valueDeclaration + ? !getEffectiveTypeAnnotationNode(parameter.valueDeclaration as ParameterDeclaration) + // a declarationless parameter may still have a `.type` already set by its construction logic + // (which may pull a type from a jsdoc) - only allow fixing on `DeferredType` parameters with a fallback type + : !!(getCheckFlags(parameter) & CheckFlags.DeferredType) + ) { + const contextualParameterType = getRestTypeAtPosition(context, len); + assignParameterType(parameter, contextualParameterType); + } + } + } + + function assignNonContextualParameterTypes(signature: Signature) { + if (signature.thisParameter) { + assignParameterType(signature.thisParameter); + } + for (const parameter of signature.parameters) { + assignParameterType(parameter); + } + } + + function assignParameterType(parameter: Symbol, contextualType?: Type) { + const links = getSymbolLinks(parameter); + if (!links.type) { + const declaration = parameter.valueDeclaration as ParameterDeclaration | undefined; + links.type = addOptionality( + contextualType || (declaration ? getWidenedTypeForVariableLikeDeclaration(declaration, /*reportErrors*/ true) : getTypeOfSymbol(parameter)), + /*isProperty*/ false, + /*isOptional*/ !!declaration && !declaration.initializer && isOptionalDeclaration(declaration), + ); + if (declaration && declaration.name.kind !== SyntaxKind.Identifier) { + // if inference didn't come up with anything but unknown, fall back to the binding pattern if present. + if (links.type === unknownType) { + links.type = getTypeFromBindingPattern(declaration.name); + } + assignBindingElementTypes(declaration.name, links.type); + } + } + else if (contextualType) { + Debug.assertEqual(links.type, contextualType, "Parameter symbol already has a cached type which differs from newly assigned type"); + } + } + + // When contextual typing assigns a type to a parameter that contains a binding pattern, we also need to push + // the destructured type into the contained binding elements. + function assignBindingElementTypes(pattern: BindingPattern, parentType: Type) { + for (const element of pattern.elements) { + if (!isOmittedExpression(element)) { + const type = getBindingElementTypeFromParentType(element, parentType, /*noTupleBoundsCheck*/ false); + if (element.name.kind === SyntaxKind.Identifier) { + getSymbolLinks(getSymbolOfDeclaration(element)).type = type; + } + else { + assignBindingElementTypes(element.name, type); + } + } + } + } + + function createClassDecoratorContextType(classType: Type) { + return tryCreateTypeReference(getGlobalClassDecoratorContextType(/*reportErrors*/ true), [classType]); + } + + function createClassMethodDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassMethodDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassGetterDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassGetterDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassSetterDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassSetterDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassAccessorDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassAccessorDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassFieldDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassFieldDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + /** + * Gets a type like `{ name: "foo", private: false, static: true }` that is used to provided member-specific + * details that will be intersected with a decorator context type. + */ + function getClassMemberDecoratorContextOverrideType(nameType: Type, isPrivate: boolean, isStatic: boolean) { + const key = `${isPrivate ? "p" : "P"}${isStatic ? "s" : "S"}${nameType.id}` as const; + let overrideType = decoratorContextOverrideTypeCache.get(key); + if (!overrideType) { + const members = createSymbolTable(); + members.set("name" as __String, createProperty("name" as __String, nameType)); + members.set("private" as __String, createProperty("private" as __String, isPrivate ? trueType : falseType)); + members.set("static" as __String, createProperty("static" as __String, isStatic ? trueType : falseType)); + overrideType = createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, emptyArray); + decoratorContextOverrideTypeCache.set(key, overrideType); + } + return overrideType; + } + + function createClassMemberDecoratorContextTypeForNode(node: MethodDeclaration | AccessorDeclaration | PropertyDeclaration, thisType: Type, valueType: Type) { + const isStatic = hasStaticModifier(node); + const isPrivate = isPrivateIdentifier(node.name); + const nameType = isPrivate ? getStringLiteralType(idText(node.name)) : getLiteralTypeFromPropertyName(node.name); + const contextType = isMethodDeclaration(node) ? createClassMethodDecoratorContextType(thisType, valueType) : + isGetAccessorDeclaration(node) ? createClassGetterDecoratorContextType(thisType, valueType) : + isSetAccessorDeclaration(node) ? createClassSetterDecoratorContextType(thisType, valueType) : + isAutoAccessorPropertyDeclaration(node) ? createClassAccessorDecoratorContextType(thisType, valueType) : + isPropertyDeclaration(node) ? createClassFieldDecoratorContextType(thisType, valueType) : + Debug.failBadSyntaxKind(node); + const overrideType = getClassMemberDecoratorContextOverrideType(nameType, isPrivate, isStatic); + return getIntersectionType([contextType, overrideType]); + } + + function createClassAccessorDecoratorTargetType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassAccessorDecoratorTargetType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassAccessorDecoratorResultType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassAccessorDecoratorResultType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassFieldDecoratorInitializerMutatorType(thisType: Type, valueType: Type) { + const thisParam = createParameter("this" as __String, thisType); + const valueParam = createParameter("value" as __String, valueType); + return createFunctionType(/*typeParameters*/ undefined, thisParam, [valueParam], valueType, /*typePredicate*/ undefined, 1); + } + + /** + * Creates a call signature for an ES Decorator. This method is used by the semantics of + * `getESDecoratorCallSignature`, which you should probably be using instead. + */ + function createESDecoratorCallSignature(targetType: Type, contextType: Type, nonOptionalReturnType: Type) { + const targetParam = createParameter("target" as __String, targetType); + const contextParam = createParameter("context" as __String, contextType); + const returnType = getUnionType([nonOptionalReturnType, voidType]); + return createCallSignature(/*typeParameters*/ undefined, /*thisParameter*/ undefined, [targetParam, contextParam], returnType); + } + + /** + * Gets a call signature that should be used when resolving `decorator` as a call. This does not use the value + * of the decorator itself, but instead uses the declaration on which it is placed along with its relative + * position amongst other decorators on the same declaration to determine the applicable signature. The + * resulting signature can be used for call resolution, inference, and contextual typing. + */ + function getESDecoratorCallSignature(decorator: Decorator) { + // We are considering a future change that would allow the type of a decorator to affect the type of the + // class and its members, such as a `@Stringify` decorator changing the type of a `number` field to `string`, or + // a `@Callable` decorator adding a call signature to a `class`. The type arguments for the various context + // types may eventually change to reflect such mutations. + // + // In some cases we describe such potential mutations as coming from a "prior decorator application". It is + // important to note that, while decorators are *evaluated* left to right, they are *applied* right to left + // to preserve f ৹ g -> f(g(x)) application order. In these cases, a "prior" decorator usually means the + // next decorator following this one in document order. + // + // The "original type" of a class or member is the type it was declared as, or the type we infer from + // initializers, before _any_ decorators are applied. + // + // The type of a class or member that is a result of a prior decorator application represents the + // "current type", i.e., the type for the declaration at the time the decorator is _applied_. + // + // The type of a class or member that is the result of the application of *all* relevant decorators is the + // "final type". + // + // Any decorator that allows mutation or replacement will also refer to an "input type" and an + // "output type". The "input type" corresponds to the "current type" of the declaration, while the + // "output type" will become either the "input type/current type" for a subsequent decorator application, + // or the "final type" for the decorated declaration. + // + // It is important to understand decorator application order as it relates to how the "current", "input", + // "output", and "final" types will be determined: + // + // @E2 @E1 class SomeClass { + // @A2 @A1 static f() {} + // @B2 @B1 g() {} + // @C2 @C1 static x; + // @D2 @D1 y; + // } + // + // Per [the specification][1], decorators are applied in the following order: + // + // 1. For each static method (incl. get/set methods and `accessor` fields), in document order: + // a. Apply each decorator for that method, in reverse order (`A1`, `A2`). + // 2. For each instance method (incl. get/set methods and `accessor` fields), in document order: + // a. Apply each decorator for that method, in reverse order (`B1`, `B2`). + // 3. For each static field (excl. auto-accessors), in document order: + // a. Apply each decorator for that field, in reverse order (`C1`, `C2`). + // 4. For each instance field (excl. auto-accessors), in document order: + // a. Apply each decorator for that field, in reverse order (`D1`, `D2`). + // 5. Apply each decorator for the class, in reverse order (`E1`, `E2`). + // + // As a result, "current" types at each decorator application are as follows: + // - For `A1`, the "current" types of the class and method are their "original" types. + // - For `A2`, the "current type" of the method is the "output type" of `A1`, and the "current type" of the + // class is the type of `SomeClass` where `f` is the "output type" of `A1`. This becomes the "final type" + // of `f`. + // - For `B1`, the "current type" of the method is its "original type", and the "current type" of the class + // is the type of `SomeClass` where `f` now has its "final type". + // - etc. + // + // [1]: https://arai-a.github.io/ecma262-compare/?pr=2417&id=sec-runtime-semantics-classdefinitionevaluation + // + // This seems complicated at first glance, but is not unlike our existing inference for functions: + // + // declare function pipe( + // original: Original, + // a1: (input: Original, context: Context) => A1, + // a2: (input: A1, context: Context) => A2, + // b1: (input: A2, context: Context) => B1, + // b2: (input: B1, context: Context) => B2, + // c1: (input: B2, context: Context) => C1, + // c2: (input: C1, context: Context) => C2, + // d1: (input: C2, context: Context) => D1, + // d2: (input: D1, context: Context) => D2, + // e1: (input: D2, context: Context) => E1, + // e2: (input: E1, context: Context) => E2, + // ): E2; + + // When a decorator is applied, it is passed two arguments: "target", which is a value representing the + // thing being decorated (constructors for classes, functions for methods/accessors, `undefined` for fields, + // and a `{ get, set }` object for auto-accessors), and "context", which is an object that provides + // reflection information about the decorated element, as well as the ability to add additional "extra" + // initializers. In most cases, the "target" argument corresponds to the "input type" in some way, and the + // return value similarly corresponds to the "output type" (though if the "output type" is `void` or + // `undefined` then the "output type" is the "input type"). + + const { parent } = decorator; + const links = getNodeLinks(parent); + if (!links.decoratorSignature) { + links.decoratorSignature = anySignature; + switch (parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: { + // Class decorators have a `context` of `ClassDecoratorContext`, where the `Class` type + // argument will be the "final type" of the class after all decorators are applied. + + const node = parent as ClassDeclaration | ClassExpression; + const targetType = getTypeOfSymbol(getSymbolOfDeclaration(node)); + const contextType = createClassDecoratorContextType(targetType); + links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, targetType); + break; + } + + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: { + const node = parent as MethodDeclaration | GetAccessorDeclaration | SetAccessorDeclaration; + if (!isClassLike(node.parent)) break; + + // Method decorators have a `context` of `ClassMethodDecoratorContext`, where the + // `Value` type argument corresponds to the "final type" of the method. + // + // Getter decorators have a `context` of `ClassGetterDecoratorContext`, where the + // `Value` type argument corresponds to the "final type" of the value returned by the getter. + // + // Setter decorators have a `context` of `ClassSetterDecoratorContext`, where the + // `Value` type argument corresponds to the "final type" of the parameter of the setter. + // + // In all three cases, the `This` type argument is the "final type" of either the class or + // instance, depending on whether the member was `static`. + + const valueType = isMethodDeclaration(node) ? getOrCreateTypeFromSignature(getSignatureFromDeclaration(node)) : + getTypeOfNode(node); + + const thisType = hasStaticModifier(node) ? + getTypeOfSymbol(getSymbolOfDeclaration(node.parent)) : + getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node.parent)); + + // We wrap the "input type", if necessary, to match the decoration target. For getters this is + // something like `() => inputType`, for setters it's `(value: inputType) => void` and for + // methods it is just the input type. + const targetType = isGetAccessorDeclaration(node) ? createGetterFunctionType(valueType) : + isSetAccessorDeclaration(node) ? createSetterFunctionType(valueType) : + valueType; + + const contextType = createClassMemberDecoratorContextTypeForNode(node, thisType, valueType); + + // We also wrap the "output type", as needed. + const returnType = isGetAccessorDeclaration(node) ? createGetterFunctionType(valueType) : + isSetAccessorDeclaration(node) ? createSetterFunctionType(valueType) : + valueType; + + links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, returnType); + break; + } + + case SyntaxKind.PropertyDeclaration: { + const node = parent as PropertyDeclaration; + if (!isClassLike(node.parent)) break; + + // Field decorators have a `context` of `ClassFieldDecoratorContext` and + // auto-accessor decorators have a `context` of `ClassAccessorDecoratorContext. In + // both cases, the `This` type argument is the "final type" of either the class or instance, + // depending on whether the member was `static`, and the `Value` type argument corresponds to + // the "final type" of the value stored in the field. + + const valueType = getTypeOfNode(node); + const thisType = hasStaticModifier(node) ? + getTypeOfSymbol(getSymbolOfDeclaration(node.parent)) : + getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node.parent)); + + // The `target` of an auto-accessor decorator is a `{ get, set }` object, representing the + // runtime-generated getter and setter that are added to the class/prototype. The `target` of a + // regular field decorator is always `undefined` as it isn't installed until it is initialized. + const targetType = hasAccessorModifier(node) ? createClassAccessorDecoratorTargetType(thisType, valueType) : + undefinedType; + + const contextType = createClassMemberDecoratorContextTypeForNode(node, thisType, valueType); + + // We wrap the "output type" depending on the declaration. For auto-accessors, we wrap the + // "output type" in a `ClassAccessorDecoratorResult` type, which allows for + // mutation of the runtime-generated getter and setter, as well as the injection of an + // initializer mutator. For regular fields, we wrap the "output type" in an initializer mutator. + const returnType = hasAccessorModifier(node) ? createClassAccessorDecoratorResultType(thisType, valueType) : + createClassFieldDecoratorInitializerMutatorType(thisType, valueType); + + links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, returnType); + break; + } + } + } + return links.decoratorSignature === anySignature ? undefined : links.decoratorSignature; + } + + function getLegacyDecoratorCallSignature(decorator: Decorator) { + const { parent } = decorator; + const links = getNodeLinks(parent); + if (!links.decoratorSignature) { + links.decoratorSignature = anySignature; + switch (parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: { + const node = parent as ClassDeclaration | ClassExpression; + // For a class decorator, the `target` is the type of the class (e.g. the + // "static" or "constructor" side of the class). + const targetType = getTypeOfSymbol(getSymbolOfDeclaration(node)); + const targetParam = createParameter("target" as __String, targetType); + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam], + getUnionType([targetType, voidType]), + ); + break; + } + case SyntaxKind.Parameter: { + const node = parent as ParameterDeclaration; + if ( + !isConstructorDeclaration(node.parent) && + !(isMethodDeclaration(node.parent) || isSetAccessorDeclaration(node.parent) && isClassLike(node.parent.parent)) + ) { + break; + } + + if (getThisParameter(node.parent) === node) { + break; + } + + const index = getThisParameter(node.parent) ? + node.parent.parameters.indexOf(node) - 1 : + node.parent.parameters.indexOf(node); + Debug.assert(index >= 0); + + // A parameter declaration decorator will have three arguments (see `ParameterDecorator` in + // core.d.ts). + + const targetType = isConstructorDeclaration(node.parent) ? getTypeOfSymbol(getSymbolOfDeclaration(node.parent.parent)) : + getParentTypeOfClassElement(node.parent); + + const keyType = isConstructorDeclaration(node.parent) ? undefinedType : + getClassElementPropertyKeyType(node.parent); + + const indexType = getNumberLiteralType(index); + + const targetParam = createParameter("target" as __String, targetType); + const keyParam = createParameter("propertyKey" as __String, keyType); + const indexParam = createParameter("parameterIndex" as __String, indexType); + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam, keyParam, indexParam], + voidType, + ); + break; + } + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.PropertyDeclaration: { + const node = parent as MethodDeclaration | AccessorDeclaration | PropertyDeclaration; + if (!isClassLike(node.parent)) break; + + // A method or accessor declaration decorator will have either two or three arguments (see + // `PropertyDecorator` and `MethodDecorator` in core.d.ts). + + const targetType = getParentTypeOfClassElement(node); + const targetParam = createParameter("target" as __String, targetType); + + const keyType = getClassElementPropertyKeyType(node); + const keyParam = createParameter("propertyKey" as __String, keyType); + + const returnType = isPropertyDeclaration(node) ? voidType : + createTypedPropertyDescriptorType(getTypeOfNode(node)); + + const hasPropDesc = !isPropertyDeclaration(parent) || hasAccessorModifier(parent); + if (hasPropDesc) { + const descriptorType = createTypedPropertyDescriptorType(getTypeOfNode(node)); + const descriptorParam = createParameter("descriptor" as __String, descriptorType); + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam, keyParam, descriptorParam], + getUnionType([returnType, voidType]), + ); + } + else { + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam, keyParam], + getUnionType([returnType, voidType]), + ); + } + break; + } + } + } + return links.decoratorSignature === anySignature ? undefined : links.decoratorSignature; + } + + function getDecoratorCallSignature(decorator: Decorator) { + return legacyDecorators ? getLegacyDecoratorCallSignature(decorator) : + getESDecoratorCallSignature(decorator); + } + + function createPromiseType(promisedType: Type): Type { + // creates a `Promise` type where `T` is the promisedType argument + const globalPromiseType = getGlobalPromiseType(/*reportErrors*/ true); + if (globalPromiseType !== emptyGenericType) { + // if the promised type is itself a promise, get the underlying type; otherwise, fallback to the promised type + // Unwrap an `Awaited` to `T` to improve inference. + promisedType = getAwaitedTypeNoAlias(unwrapAwaitedType(promisedType)) || unknownType; + return createTypeReference(globalPromiseType, [promisedType]); + } + + return unknownType; + } + + function createPromiseLikeType(promisedType: Type): Type { + // creates a `PromiseLike` type where `T` is the promisedType argument + const globalPromiseLikeType = getGlobalPromiseLikeType(/*reportErrors*/ true); + if (globalPromiseLikeType !== emptyGenericType) { + // if the promised type is itself a promise, get the underlying type; otherwise, fallback to the promised type + // Unwrap an `Awaited` to `T` to improve inference. + promisedType = getAwaitedTypeNoAlias(unwrapAwaitedType(promisedType)) || unknownType; + return createTypeReference(globalPromiseLikeType, [promisedType]); + } + + return unknownType; + } + + function createPromiseReturnType(func: FunctionLikeDeclaration | ImportCall, promisedType: Type) { + const promiseType = createPromiseType(promisedType); + if (promiseType === unknownType) { + error( + func, + isImportCall(func) ? + Diagnostics.A_dynamic_import_call_returns_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option : + Diagnostics.An_async_function_or_method_must_return_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option, + ); + return errorType; + } + else if (!getGlobalPromiseConstructorSymbol(/*reportErrors*/ true)) { + error( + func, + isImportCall(func) ? + Diagnostics.A_dynamic_import_call_in_ES5_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option : + Diagnostics.An_async_function_or_method_in_ES5_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option, + ); + } + + return promiseType; + } + + function createNewTargetExpressionType(targetType: Type): Type { + // Create a synthetic type `NewTargetExpression { target: TargetType; }` + const symbol = createSymbol(SymbolFlags.None, "NewTargetExpression" as __String); + + const targetPropertySymbol = createSymbol(SymbolFlags.Property, "target" as __String, CheckFlags.Readonly); + targetPropertySymbol.parent = symbol; + targetPropertySymbol.links.type = targetType; + + const members = createSymbolTable([targetPropertySymbol]); + symbol.members = members; + return createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + } + + function getReturnTypeFromBody(func: FunctionLikeDeclaration, checkMode?: CheckMode): Type { + if (!func.body) { + return errorType; + } + + const functionFlags = getFunctionFlags(func); + const isAsync = (functionFlags & FunctionFlags.Async) !== 0; + const isGenerator = (functionFlags & FunctionFlags.Generator) !== 0; + + let returnType: Type | undefined; + let yieldType: Type | undefined; + let nextType: Type | undefined; + let fallbackReturnType: Type = voidType; + if (func.body.kind !== SyntaxKind.Block) { // Async or normal arrow function + returnType = checkExpressionCached(func.body, checkMode && checkMode & ~CheckMode.SkipGenericFunctions); + if (isAsync) { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so the + // return type of the body should be unwrapped to its awaited type, which we will wrap in + // the native Promise type later in this function. + returnType = unwrapAwaitedType(checkAwaitedType(returnType, /*withAlias*/ false, /*errorNode*/ func, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member)); + } + } + else if (isGenerator) { // Generator or AsyncGenerator function + const returnTypes = checkAndAggregateReturnExpressionTypes(func, checkMode); + if (!returnTypes) { + fallbackReturnType = neverType; + } + else if (returnTypes.length > 0) { + returnType = getUnionType(returnTypes, UnionReduction.Subtype); + } + const { yieldTypes, nextTypes } = checkAndAggregateYieldOperandTypes(func, checkMode); + yieldType = some(yieldTypes) ? getUnionType(yieldTypes, UnionReduction.Subtype) : undefined; + nextType = some(nextTypes) ? getIntersectionType(nextTypes) : undefined; + } + else { // Async or normal function + const types = checkAndAggregateReturnExpressionTypes(func, checkMode); + if (!types) { + // For an async function, the return type will not be never, but rather a Promise for never. + return functionFlags & FunctionFlags.Async + ? createPromiseReturnType(func, neverType) // Async function + : neverType; // Normal function + } + if (types.length === 0) { + // For an async function, the return type will not be void/undefined, but rather a Promise for void/undefined. + const contextualReturnType = getContextualReturnType(func, /*contextFlags*/ undefined); + const returnType = contextualReturnType && (unwrapReturnType(contextualReturnType, functionFlags) || voidType).flags & TypeFlags.Undefined ? undefinedType : voidType; + return functionFlags & FunctionFlags.Async ? createPromiseReturnType(func, returnType) : // Async function + returnType; // Normal function + } + + // Return a union of the return expression types. + returnType = getUnionType(types, UnionReduction.Subtype); + } + + if (returnType || yieldType || nextType) { + if (yieldType) reportErrorsFromWidening(func, yieldType, WideningKind.GeneratorYield); + if (returnType) reportErrorsFromWidening(func, returnType, WideningKind.FunctionReturn); + if (nextType) reportErrorsFromWidening(func, nextType, WideningKind.GeneratorNext); + if ( + returnType && isUnitType(returnType) || + yieldType && isUnitType(yieldType) || + nextType && isUnitType(nextType) + ) { + const contextualSignature = getContextualSignatureForFunctionLikeDeclaration(func); + const contextualType = !contextualSignature ? undefined : + contextualSignature === getSignatureFromDeclaration(func) ? isGenerator ? undefined : returnType : + instantiateContextualType(getReturnTypeOfSignature(contextualSignature), func, /*contextFlags*/ undefined); + if (isGenerator) { + yieldType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(yieldType, contextualType, IterationTypeKind.Yield, isAsync); + returnType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(returnType, contextualType, IterationTypeKind.Return, isAsync); + nextType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(nextType, contextualType, IterationTypeKind.Next, isAsync); + } + else { + returnType = getWidenedLiteralLikeTypeForContextualReturnTypeIfNeeded(returnType, contextualType, isAsync); + } + } + + if (yieldType) yieldType = getWidenedType(yieldType); + if (returnType) returnType = getWidenedType(returnType); + if (nextType) nextType = getWidenedType(nextType); + } + + if (isGenerator) { + return createGeneratorType( + yieldType || neverType, + returnType || fallbackReturnType, + nextType || getContextualIterationType(IterationTypeKind.Next, func) || unknownType, + isAsync, + ); + } + else { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so the + // return type of the body is awaited type of the body, wrapped in a native Promise type. + return isAsync + ? createPromiseType(returnType || fallbackReturnType) + : returnType || fallbackReturnType; + } + } + + function createGeneratorType(yieldType: Type, returnType: Type, nextType: Type, isAsyncGenerator: boolean) { + const resolver = isAsyncGenerator ? asyncIterationTypesResolver : syncIterationTypesResolver; + const globalGeneratorType = resolver.getGlobalGeneratorType(/*reportErrors*/ false); + yieldType = resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || unknownType; + returnType = resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || unknownType; + nextType = resolver.resolveIterationType(nextType, /*errorNode*/ undefined) || unknownType; + if (globalGeneratorType === emptyGenericType) { + // Fall back to the global IterableIterator if returnType is assignable to the expected return iteration + // type of IterableIterator, and the expected next iteration type of IterableIterator is assignable to + // nextType. + const globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false); + const iterationTypes = globalType !== emptyGenericType ? getIterationTypesOfGlobalIterableType(globalType, resolver) : undefined; + const iterableIteratorReturnType = iterationTypes ? iterationTypes.returnType : anyType; + const iterableIteratorNextType = iterationTypes ? iterationTypes.nextType : undefinedType; + if ( + isTypeAssignableTo(returnType, iterableIteratorReturnType) && + isTypeAssignableTo(iterableIteratorNextType, nextType) + ) { + if (globalType !== emptyGenericType) { + return createTypeFromGenericGlobalType(globalType, [yieldType]); + } + + // The global IterableIterator type doesn't exist, so report an error + resolver.getGlobalIterableIteratorType(/*reportErrors*/ true); + return emptyObjectType; + } + + // The global Generator type doesn't exist, so report an error + resolver.getGlobalGeneratorType(/*reportErrors*/ true); + return emptyObjectType; + } + + return createTypeFromGenericGlobalType(globalGeneratorType, [yieldType, returnType, nextType]); + } + + function checkAndAggregateYieldOperandTypes(func: FunctionLikeDeclaration, checkMode: CheckMode | undefined) { + const yieldTypes: Type[] = []; + const nextTypes: Type[] = []; + const isAsync = (getFunctionFlags(func) & FunctionFlags.Async) !== 0; + forEachYieldExpression(func.body as Block, yieldExpression => { + const yieldExpressionType = yieldExpression.expression ? checkExpression(yieldExpression.expression, checkMode) : undefinedWideningType; + pushIfUnique(yieldTypes, getYieldedTypeOfYieldExpression(yieldExpression, yieldExpressionType, anyType, isAsync)); + let nextType: Type | undefined; + if (yieldExpression.asteriskToken) { + const iterationTypes = getIterationTypesOfIterable( + yieldExpressionType, + isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar, + yieldExpression.expression, + ); + nextType = iterationTypes && iterationTypes.nextType; + } + else { + nextType = getContextualType(yieldExpression, /*contextFlags*/ undefined); + } + if (nextType) pushIfUnique(nextTypes, nextType); + }); + return { yieldTypes, nextTypes }; + } + + function getYieldedTypeOfYieldExpression(node: YieldExpression, expressionType: Type, sentType: Type, isAsync: boolean): Type | undefined { + const errorNode = node.expression || node; + // A `yield*` expression effectively yields everything that its operand yields + const yieldedType = node.asteriskToken ? checkIteratedTypeOrElementType(isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar, expressionType, sentType, errorNode) : expressionType; + return !isAsync ? yieldedType : getAwaitedType( + yieldedType, + errorNode, + node.asteriskToken + ? Diagnostics.Type_of_iterated_elements_of_a_yield_Asterisk_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member + : Diagnostics.Type_of_yield_operand_in_an_async_generator_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member, + ); + } + + // Return the combined not-equal type facts for all cases except those between the start and end indices. + function getNotEqualFactsFromTypeofSwitch(start: number, end: number, witnesses: (string | undefined)[]): TypeFacts { + let facts: TypeFacts = TypeFacts.None; + for (let i = 0; i < witnesses.length; i++) { + const witness = i < start || i >= end ? witnesses[i] : undefined; + facts |= witness !== undefined ? typeofNEFacts.get(witness) || TypeFacts.TypeofNEHostObject : 0; + } + return facts; + } + + function isExhaustiveSwitchStatement(node: SwitchStatement): boolean { + const links = getNodeLinks(node); + if (links.isExhaustive === undefined) { + links.isExhaustive = 0; // Indicate resolution is in process + const exhaustive = computeExhaustiveSwitchStatement(node); + if (links.isExhaustive === 0) { + links.isExhaustive = exhaustive; + } + } + else if (links.isExhaustive === 0) { + links.isExhaustive = false; // Resolve circularity to false + } + return links.isExhaustive; + } + + function computeExhaustiveSwitchStatement(node: SwitchStatement): boolean { + if (node.expression.kind === SyntaxKind.TypeOfExpression) { + const witnesses = getSwitchClauseTypeOfWitnesses(node); + if (!witnesses) { + return false; + } + const operandConstraint = getBaseConstraintOrType(checkExpressionCached((node.expression as TypeOfExpression).expression)); + // Get the not-equal flags for all handled cases. + const notEqualFacts = getNotEqualFactsFromTypeofSwitch(0, 0, witnesses); + if (operandConstraint.flags & TypeFlags.AnyOrUnknown) { + // We special case the top types to be exhaustive when all cases are handled. + return (TypeFacts.AllTypeofNE & notEqualFacts) === TypeFacts.AllTypeofNE; + } + // A missing not-equal flag indicates that the type wasn't handled by some case. + return !someType(operandConstraint, t => getTypeFacts(t, notEqualFacts) === notEqualFacts); + } + const type = checkExpressionCached(node.expression); + if (!isLiteralType(type)) { + return false; + } + const switchTypes = getSwitchClauseTypes(node); + if (!switchTypes.length || some(switchTypes, isNeitherUnitTypeNorNever)) { + return false; + } + return eachTypeContainedIn(mapType(type, getRegularTypeOfLiteralType), switchTypes); + } + + function functionHasImplicitReturn(func: FunctionLikeDeclaration) { + return func.endFlowNode && isReachableFlowNode(func.endFlowNode); + } + + /** NOTE: Return value of `[]` means a different thing than `undefined`. `[]` means func returns `void`, `undefined` means it returns `never`. */ + function checkAndAggregateReturnExpressionTypes(func: FunctionLikeDeclaration, checkMode: CheckMode | undefined): Type[] | undefined { + const functionFlags = getFunctionFlags(func); + const aggregatedTypes: Type[] = []; + let hasReturnWithNoExpression = functionHasImplicitReturn(func); + let hasReturnOfTypeNever = false; + forEachReturnStatement(func.body as Block, returnStatement => { + let expr = returnStatement.expression; + if (expr) { + expr = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + // Bare calls to this same function don't contribute to inference + // and `return await` is also safe to unwrap here + if (functionFlags & FunctionFlags.Async && expr.kind === SyntaxKind.AwaitExpression) { + expr = skipParentheses((expr as AwaitExpression).expression, /*excludeJSDocTypeAssertions*/ true); + } + if ( + expr.kind === SyntaxKind.CallExpression && + (expr as CallExpression).expression.kind === SyntaxKind.Identifier && + checkExpressionCached((expr as CallExpression).expression).symbol === getMergedSymbol(func.symbol) && + (!isFunctionExpressionOrArrowFunction(func.symbol.valueDeclaration!) || isConstantReference((expr as CallExpression).expression)) + ) { + hasReturnOfTypeNever = true; + return; + } + + let type = checkExpressionCached(expr, checkMode && checkMode & ~CheckMode.SkipGenericFunctions); + if (functionFlags & FunctionFlags.Async) { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so the + // return type of the body should be unwrapped to its awaited type, which should be wrapped in + // the native Promise type by the caller. + type = unwrapAwaitedType(checkAwaitedType(type, /*withAlias*/ false, func, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member)); + } + if (type.flags & TypeFlags.Never) { + hasReturnOfTypeNever = true; + } + pushIfUnique(aggregatedTypes, type); + } + else { + hasReturnWithNoExpression = true; + } + }); + if (aggregatedTypes.length === 0 && !hasReturnWithNoExpression && (hasReturnOfTypeNever || mayReturnNever(func))) { + return undefined; + } + if ( + strictNullChecks && aggregatedTypes.length && hasReturnWithNoExpression && + !(isJSConstructor(func) && aggregatedTypes.some(t => t.symbol === func.symbol)) + ) { + // Javascript "callable constructors", containing eg `if (!(this instanceof A)) return new A()` should not add undefined + pushIfUnique(aggregatedTypes, undefinedType); + } + return aggregatedTypes; + } + function mayReturnNever(func: FunctionLikeDeclaration): boolean { + switch (func.kind) { + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + return true; + case SyntaxKind.MethodDeclaration: + return func.parent.kind === SyntaxKind.ObjectLiteralExpression; + default: + return false; + } + } + + function getTypePredicateFromBody(func: FunctionLikeDeclaration): TypePredicate | undefined { + switch (func.kind) { + case SyntaxKind.Constructor: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return undefined; + } + const functionFlags = getFunctionFlags(func); + if (functionFlags !== FunctionFlags.Normal) return undefined; + + // Only attempt to infer a type predicate if there's exactly one return. + let singleReturn: Expression | undefined; + if (func.body && func.body.kind !== SyntaxKind.Block) { + singleReturn = func.body; // arrow function + } + else { + const bailedEarly = forEachReturnStatement(func.body as Block, returnStatement => { + if (singleReturn || !returnStatement.expression) return true; + singleReturn = returnStatement.expression; + }); + if (bailedEarly || !singleReturn || functionHasImplicitReturn(func)) return undefined; + } + return checkIfExpressionRefinesAnyParameter(func, singleReturn); + } + + function checkIfExpressionRefinesAnyParameter(func: FunctionLikeDeclaration, expr: Expression): TypePredicate | undefined { + expr = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + const returnType = checkExpressionCached(expr); + if (!(returnType.flags & TypeFlags.Boolean)) return undefined; + + return forEach(func.parameters, (param, i) => { + const initType = getTypeOfSymbol(param.symbol); + if (!initType || initType.flags & TypeFlags.Boolean || !isIdentifier(param.name) || isSymbolAssigned(param.symbol) || isRestParameter(param)) { + // Refining "x: boolean" to "x is true" or "x is false" isn't useful. + return; + } + const trueType = checkIfExpressionRefinesParameter(func, expr, param, initType); + if (trueType) { + return createTypePredicate(TypePredicateKind.Identifier, unescapeLeadingUnderscores(param.name.escapedText), i, trueType); + } + }); + } + + function checkIfExpressionRefinesParameter(func: FunctionLikeDeclaration, expr: Expression, param: ParameterDeclaration, initType: Type): Type | undefined { + const antecedent = (expr as Expression & { flowNode?: FlowNode; }).flowNode || + expr.parent.kind === SyntaxKind.ReturnStatement && (expr.parent as ReturnStatement).flowNode || + createFlowNode(FlowFlags.Start, /*node*/ undefined, /*antecedent*/ undefined); + const trueCondition = createFlowNode(FlowFlags.TrueCondition, expr, antecedent); + + const trueType = getFlowTypeOfReference(param.name, initType, initType, func, trueCondition); + if (trueType === initType) return undefined; + + // "x is T" means that x is T if and only if it returns true. If it returns false then x is not T. + // This means that if the function is called with an argument of type trueType, there can't be anything left in the `else` branch. It must reduce to `never`. + const falseCondition = createFlowNode(FlowFlags.FalseCondition, expr, antecedent); + const falseSubtype = getFlowTypeOfReference(param.name, initType, trueType, func, falseCondition); + return falseSubtype.flags & TypeFlags.Never ? trueType : undefined; + } + + /** + * TypeScript Specification 1.0 (6.3) - July 2014 + * An explicitly typed function whose return type isn't the Void type, + * the Any type, or a union type containing the Void or Any type as a constituent + * must have at least one return statement somewhere in its body. + * An exception to this rule is if the function implementation consists of a single 'throw' statement. + * + * @param returnType - return type of the function, can be undefined if return type is not explicitly specified + */ + function checkAllCodePathsInNonVoidFunctionReturnOrThrow(func: FunctionLikeDeclaration | MethodSignature, returnType: Type | undefined) { + addLazyDiagnostic(checkAllCodePathsInNonVoidFunctionReturnOrThrowDiagnostics); + return; + + function checkAllCodePathsInNonVoidFunctionReturnOrThrowDiagnostics(): void { + const functionFlags = getFunctionFlags(func); + const type = returnType && unwrapReturnType(returnType, functionFlags); + + // Functions with an explicitly specified return type that includes `void` or is exactly `any` or `undefined` don't + // need any return statements. + if (type && (maybeTypeOfKind(type, TypeFlags.Void) || type.flags & (TypeFlags.Any | TypeFlags.Undefined))) { + return; + } + + // If all we have is a function signature, or an arrow function with an expression body, then there is nothing to check. + // also if HasImplicitReturn flag is not set this means that all codepaths in function body end with return or throw + if (func.kind === SyntaxKind.MethodSignature || nodeIsMissing(func.body) || func.body!.kind !== SyntaxKind.Block || !functionHasImplicitReturn(func)) { + return; + } + + const hasExplicitReturn = func.flags & NodeFlags.HasExplicitReturn; + const errorNode = getEffectiveReturnTypeNode(func) || func; + + if (type && type.flags & TypeFlags.Never) { + error(errorNode, Diagnostics.A_function_returning_never_cannot_have_a_reachable_end_point); + } + else if (type && !hasExplicitReturn) { + // minimal check: function has syntactic return type annotation and no explicit return statements in the body + // this function does not conform to the specification. + error(errorNode, Diagnostics.A_function_whose_declared_type_is_neither_undefined_void_nor_any_must_return_a_value); + } + else if (type && strictNullChecks && !isTypeAssignableTo(undefinedType, type)) { + error(errorNode, Diagnostics.Function_lacks_ending_return_statement_and_return_type_does_not_include_undefined); + } + else if (compilerOptions.noImplicitReturns) { + if (!type) { + // If return type annotation is omitted check if function has any explicit return statements. + // If it does not have any - its inferred return type is void - don't do any checks. + // Otherwise get inferred return type from function body and report error only if it is not void / anytype + if (!hasExplicitReturn) { + return; + } + const inferredReturnType = getReturnTypeOfSignature(getSignatureFromDeclaration(func)); + if (isUnwrappedReturnTypeUndefinedVoidOrAny(func, inferredReturnType)) { + return; + } + } + error(errorNode, Diagnostics.Not_all_code_paths_return_a_value); + } + } + } + + function checkFunctionExpressionOrObjectLiteralMethod(node: FunctionExpression | ArrowFunction | MethodDeclaration, checkMode?: CheckMode): Type { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + checkNodeDeferred(node); + + if (isFunctionExpression(node)) { + checkCollisionsForDeclarationName(node, node.name); + } + + // The identityMapper object is used to indicate that function expressions are wildcards + if (checkMode && checkMode & CheckMode.SkipContextSensitive && isContextSensitive(node)) { + // Skip parameters, return signature with return type that retains noncontextual parts so inferences can still be drawn in an early stage + if (!getEffectiveReturnTypeNode(node) && !hasContextSensitiveParameters(node)) { + // Return plain anyFunctionType if there is no possibility we'll make inferences from the return type + const contextualSignature = getContextualSignature(node); + if (contextualSignature && couldContainTypeVariables(getReturnTypeOfSignature(contextualSignature))) { + const links = getNodeLinks(node); + if (links.contextFreeType) { + return links.contextFreeType; + } + const returnType = getReturnTypeFromBody(node, checkMode); + const returnOnlySignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, returnType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.IsNonInferrable); + const returnOnlyType = createAnonymousType(node.symbol, emptySymbols, [returnOnlySignature], emptyArray, emptyArray); + returnOnlyType.objectFlags |= ObjectFlags.NonInferrableType; + return links.contextFreeType = returnOnlyType; + } + } + return anyFunctionType; + } + + // Grammar checking + const hasGrammarError = checkGrammarFunctionLikeDeclaration(node); + if (!hasGrammarError && node.kind === SyntaxKind.FunctionExpression) { + checkGrammarForGenerator(node); + } + + contextuallyCheckFunctionExpressionOrObjectLiteralMethod(node, checkMode); + + return getTypeOfSymbol(getSymbolOfDeclaration(node)); + } + + function contextuallyCheckFunctionExpressionOrObjectLiteralMethod(node: FunctionExpression | ArrowFunction | MethodDeclaration, checkMode?: CheckMode) { + const links = getNodeLinks(node); + // Check if function expression is contextually typed and assign parameter types if so. + if (!(links.flags & NodeCheckFlags.ContextChecked)) { + const contextualSignature = getContextualSignature(node); + // If a type check is started at a function expression that is an argument of a function call, obtaining the + // contextual type may recursively get back to here during overload resolution of the call. If so, we will have + // already assigned contextual types. + if (!(links.flags & NodeCheckFlags.ContextChecked)) { + links.flags |= NodeCheckFlags.ContextChecked; + const signature = firstOrUndefined(getSignaturesOfType(getTypeOfSymbol(getSymbolOfDeclaration(node)), SignatureKind.Call)); + if (!signature) { + return; + } + if (isContextSensitive(node)) { + if (contextualSignature) { + const inferenceContext = getInferenceContext(node); + let instantiatedContextualSignature: Signature | undefined; + if (checkMode && checkMode & CheckMode.Inferential) { + inferFromAnnotatedParameters(signature, contextualSignature, inferenceContext!); + const restType = getEffectiveRestType(contextualSignature); + if (restType && restType.flags & TypeFlags.TypeParameter) { + instantiatedContextualSignature = instantiateSignature(contextualSignature, inferenceContext!.nonFixingMapper); + } + } + instantiatedContextualSignature ||= inferenceContext ? + instantiateSignature(contextualSignature, inferenceContext.mapper) : contextualSignature; + assignContextualParameterTypes(signature, instantiatedContextualSignature); + } + else { + // Force resolution of all parameter types such that the absence of a contextual type is consistently reflected. + assignNonContextualParameterTypes(signature); + } + } + else if (contextualSignature && !node.typeParameters && contextualSignature.parameters.length > node.parameters.length) { + const inferenceContext = getInferenceContext(node); + if (checkMode && checkMode & CheckMode.Inferential) { + inferFromAnnotatedParameters(signature, contextualSignature, inferenceContext!); + } + } + if (contextualSignature && !getReturnTypeFromAnnotation(node) && !signature.resolvedReturnType) { + const returnType = getReturnTypeFromBody(node, checkMode); + if (!signature.resolvedReturnType) { + signature.resolvedReturnType = returnType; + } + } + checkSignatureDeclaration(node); + } + } + } + + function checkFunctionExpressionOrObjectLiteralMethodDeferred(node: ArrowFunction | FunctionExpression | MethodDeclaration) { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + + const functionFlags = getFunctionFlags(node); + const returnType = getReturnTypeFromAnnotation(node); + checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType); + + if (node.body) { + if (!getEffectiveReturnTypeNode(node)) { + // There are some checks that are only performed in getReturnTypeFromBody, that may produce errors + // we need. An example is the noImplicitAny errors resulting from widening the return expression + // of a function. Because checking of function expression bodies is deferred, there was never an + // appropriate time to do this during the main walk of the file (see the comment at the top of + // checkFunctionExpressionBodies). So it must be done now. + getReturnTypeOfSignature(getSignatureFromDeclaration(node)); + } + + if (node.body.kind === SyntaxKind.Block) { + checkSourceElement(node.body); + } + else { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so we + // should not be checking assignability of a promise to the return type. Instead, we need to + // check assignability of the awaited type of the expression body against the promised type of + // its return type annotation. + const exprType = checkExpression(node.body); + const returnOrPromisedType = returnType && unwrapReturnType(returnType, functionFlags); + if (returnOrPromisedType) { + const effectiveCheckNode = getEffectiveCheckNode(node.body); + if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async) { // Async function + const awaitedType = checkAwaitedType(exprType, /*withAlias*/ false, effectiveCheckNode, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); + checkTypeAssignableToAndOptionallyElaborate(awaitedType, returnOrPromisedType, effectiveCheckNode, effectiveCheckNode); + } + else { // Normal function + checkTypeAssignableToAndOptionallyElaborate(exprType, returnOrPromisedType, effectiveCheckNode, effectiveCheckNode); + } + } + } + } + } + + function checkArithmeticOperandType(operand: Node, type: Type, diagnostic: DiagnosticMessage, isAwaitValid = false): boolean { + if (!isTypeAssignableTo(type, numberOrBigIntType)) { + const awaitedType = isAwaitValid && getAwaitedTypeOfPromise(type); + errorAndMaybeSuggestAwait( + operand, + !!awaitedType && isTypeAssignableTo(awaitedType, numberOrBigIntType), + diagnostic, + ); + return false; + } + return true; + } + + function isReadonlyAssignmentDeclaration(d: Declaration) { + if (!isCallExpression(d)) { + return false; + } + if (!isBindableObjectDefinePropertyCall(d)) { + return false; + } + const objectLitType = checkExpressionCached(d.arguments[2]); + const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String); + if (valueType) { + const writableProp = getPropertyOfType(objectLitType, "writable" as __String); + const writableType = writableProp && getTypeOfSymbol(writableProp); + if (!writableType || writableType === falseType || writableType === regularFalseType) { + return true; + } + // We include this definition whereupon we walk back and check the type at the declaration because + // The usual definition of `Object.defineProperty` will _not_ cause literal types to be preserved in the + // argument types, should the type be contextualized by the call itself. + if (writableProp && writableProp.valueDeclaration && isPropertyAssignment(writableProp.valueDeclaration)) { + const initializer = writableProp.valueDeclaration.initializer; + const rawOriginalType = checkExpression(initializer); + if (rawOriginalType === falseType || rawOriginalType === regularFalseType) { + return true; + } + } + return false; + } + const setProp = getPropertyOfType(objectLitType, "set" as __String); + return !setProp; + } + + function isReadonlySymbol(symbol: Symbol): boolean { + // The following symbols are considered read-only: + // Properties with a 'readonly' modifier + // Variables declared with 'const' + // Get accessors without matching set accessors + // Enum members + // Object.defineProperty assignments with writable false or no setter + // Unions and intersections of the above (unions and intersections eagerly set isReadonly on creation) + return !!(getCheckFlags(symbol) & CheckFlags.Readonly || + symbol.flags & SymbolFlags.Property && getDeclarationModifierFlagsFromSymbol(symbol) & ModifierFlags.Readonly || + symbol.flags & SymbolFlags.Variable && getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Constant || + symbol.flags & SymbolFlags.Accessor && !(symbol.flags & SymbolFlags.SetAccessor) || + symbol.flags & SymbolFlags.EnumMember || + some(symbol.declarations, isReadonlyAssignmentDeclaration)); + } + + function isAssignmentToReadonlyEntity(expr: Expression, symbol: Symbol, assignmentKind: AssignmentKind) { + if (assignmentKind === AssignmentKind.None) { + // no assigment means it doesn't matter whether the entity is readonly + return false; + } + if (isReadonlySymbol(symbol)) { + // Allow assignments to readonly properties within constructors of the same class declaration. + if ( + symbol.flags & SymbolFlags.Property && + isAccessExpression(expr) && + expr.expression.kind === SyntaxKind.ThisKeyword + ) { + // Look for if this is the constructor for the class that `symbol` is a property of. + const ctor = getContainingFunction(expr); + if (!(ctor && (ctor.kind === SyntaxKind.Constructor || isJSConstructor(ctor)))) { + return true; + } + if (symbol.valueDeclaration) { + const isAssignmentDeclaration = isBinaryExpression(symbol.valueDeclaration); + const isLocalPropertyDeclaration = ctor.parent === symbol.valueDeclaration.parent; + const isLocalParameterProperty = ctor === symbol.valueDeclaration.parent; + const isLocalThisPropertyAssignment = isAssignmentDeclaration && symbol.parent?.valueDeclaration === ctor.parent; + const isLocalThisPropertyAssignmentConstructorFunction = isAssignmentDeclaration && symbol.parent?.valueDeclaration === ctor; + const isWriteableSymbol = isLocalPropertyDeclaration + || isLocalParameterProperty + || isLocalThisPropertyAssignment + || isLocalThisPropertyAssignmentConstructorFunction; + return !isWriteableSymbol; + } + } + return true; + } + if (isAccessExpression(expr)) { + // references through namespace import should be readonly + const node = skipParentheses(expr.expression); + if (node.kind === SyntaxKind.Identifier) { + const symbol = getNodeLinks(node).resolvedSymbol!; + if (symbol.flags & SymbolFlags.Alias) { + const declaration = getDeclarationOfAliasSymbol(symbol); + return !!declaration && declaration.kind === SyntaxKind.NamespaceImport; + } + } + } + return false; + } + + function checkReferenceExpression(expr: Expression, invalidReferenceMessage: DiagnosticMessage, invalidOptionalChainMessage: DiagnosticMessage): boolean { + // References are combinations of identifiers, parentheses, and property accesses. + const node = skipOuterExpressions(expr, OuterExpressionKinds.Assertions | OuterExpressionKinds.Parentheses); + if (node.kind !== SyntaxKind.Identifier && !isAccessExpression(node)) { + error(expr, invalidReferenceMessage); + return false; + } + if (node.flags & NodeFlags.OptionalChain) { + error(expr, invalidOptionalChainMessage); + return false; + } + return true; + } + + function checkDeleteExpression(node: DeleteExpression): Type { + checkExpression(node.expression); + const expr = skipParentheses(node.expression); + if (!isAccessExpression(expr)) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_must_be_a_property_reference); + return booleanType; + } + if (isPropertyAccessExpression(expr) && isPrivateIdentifier(expr.name)) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_cannot_be_a_private_identifier); + } + const links = getNodeLinks(expr); + const symbol = getExportSymbolOfValueSymbolIfExported(links.resolvedSymbol); + if (symbol) { + if (isReadonlySymbol(symbol)) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_cannot_be_a_read_only_property); + } + else { + checkDeleteExpressionMustBeOptional(expr, symbol); + } + } + return booleanType; + } + + function checkDeleteExpressionMustBeOptional(expr: AccessExpression, symbol: Symbol) { + const type = getTypeOfSymbol(symbol); + if ( + strictNullChecks && + !(type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Never)) && + !(exactOptionalPropertyTypes ? symbol.flags & SymbolFlags.Optional : hasTypeFacts(type, TypeFacts.IsUndefined)) + ) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_must_be_optional); + } + } + + function checkTypeOfExpression(node: TypeOfExpression): Type { + checkExpression(node.expression); + return typeofType; + } + + function checkVoidExpression(node: VoidExpression): Type { + checkNodeDeferred(node); + return undefinedWideningType; + } + + function checkAwaitGrammar(node: AwaitExpression | VariableDeclarationList): boolean { + // Grammar checking + let hasError = false; + const container = getContainingFunctionOrClassStaticBlock(node); + if (container && isClassStaticBlockDeclaration(container)) { + // NOTE: We report this regardless as to whether there are parse diagnostics. + const message = isAwaitExpression(node) ? Diagnostics.await_expression_cannot_be_used_inside_a_class_static_block : + Diagnostics.await_using_statements_cannot_be_used_inside_a_class_static_block; + error(node, message); + hasError = true; + } + else if (!(node.flags & NodeFlags.AwaitContext)) { + if (isInTopLevelContext(node)) { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + let span: TextSpan | undefined; + if (!isEffectiveExternalModule(sourceFile, compilerOptions)) { + span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); + const message = isAwaitExpression(node) ? Diagnostics.await_expressions_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module : + Diagnostics.await_using_statements_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module; + const diagnostic = createFileDiagnostic(sourceFile, span.start, span.length, message); + diagnostics.add(diagnostic); + hasError = true; + } + switch (moduleKind) { + case ModuleKind.Node16: + case ModuleKind.NodeNext: + if (sourceFile.impliedNodeFormat === ModuleKind.CommonJS) { + span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); + diagnostics.add( + createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.The_current_file_is_a_CommonJS_module_and_cannot_use_await_at_the_top_level), + ); + hasError = true; + break; + } + // fallthrough + case ModuleKind.ES2022: + case ModuleKind.ESNext: + case ModuleKind.Preserve: + case ModuleKind.System: + if (languageVersion >= ScriptTarget.ES2017) { + break; + } + // fallthrough + default: + span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); + const message = isAwaitExpression(node) ? Diagnostics.Top_level_await_expressions_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_nodenext_or_preserve_and_the_target_option_is_set_to_es2017_or_higher : + Diagnostics.Top_level_await_using_statements_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_nodenext_or_preserve_and_the_target_option_is_set_to_es2017_or_higher; + diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, message)); + hasError = true; + break; + } + } + } + else { + // use of 'await' in non-async function + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + const span = getSpanOfTokenAtPosition(sourceFile, node.pos); + const message = isAwaitExpression(node) ? Diagnostics.await_expressions_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules : + Diagnostics.await_using_statements_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules; + const diagnostic = createFileDiagnostic(sourceFile, span.start, span.length, message); + if (container && container.kind !== SyntaxKind.Constructor && (getFunctionFlags(container) & FunctionFlags.Async) === 0) { + const relatedInfo = createDiagnosticForNode(container, Diagnostics.Did_you_mean_to_mark_this_function_as_async); + addRelatedInfo(diagnostic, relatedInfo); + } + diagnostics.add(diagnostic); + hasError = true; + } + } + } + + if (isAwaitExpression(node) && isInParameterInitializerBeforeContainingFunction(node)) { + // NOTE: We report this regardless as to whether there are parse diagnostics. + error(node, Diagnostics.await_expressions_cannot_be_used_in_a_parameter_initializer); + hasError = true; + } + + return hasError; + } + + function checkAwaitExpression(node: AwaitExpression): Type { + addLazyDiagnostic(() => checkAwaitGrammar(node)); + + const operandType = checkExpression(node.expression); + const awaitedType = checkAwaitedType(operandType, /*withAlias*/ true, node, Diagnostics.Type_of_await_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); + if (awaitedType === operandType && !isErrorType(awaitedType) && !(operandType.flags & TypeFlags.AnyOrUnknown)) { + addErrorOrSuggestion(/*isError*/ false, createDiagnosticForNode(node, Diagnostics.await_has_no_effect_on_the_type_of_this_expression)); + } + return awaitedType; + } + + function checkPrefixUnaryExpression(node: PrefixUnaryExpression): Type { + const operandType = checkExpression(node.operand); + if (operandType === silentNeverType) { + return silentNeverType; + } + switch (node.operand.kind) { + case SyntaxKind.NumericLiteral: + switch (node.operator) { + case SyntaxKind.MinusToken: + return getFreshTypeOfLiteralType(getNumberLiteralType(-(node.operand as NumericLiteral).text)); + case SyntaxKind.PlusToken: + return getFreshTypeOfLiteralType(getNumberLiteralType(+(node.operand as NumericLiteral).text)); + } + break; + case SyntaxKind.BigIntLiteral: + if (node.operator === SyntaxKind.MinusToken) { + return getFreshTypeOfLiteralType(getBigIntLiteralType({ + negative: true, + base10Value: parsePseudoBigInt((node.operand as BigIntLiteral).text), + })); + } + } + switch (node.operator) { + case SyntaxKind.PlusToken: + case SyntaxKind.MinusToken: + case SyntaxKind.TildeToken: + checkNonNullType(operandType, node.operand); + if (maybeTypeOfKindConsideringBaseConstraint(operandType, TypeFlags.ESSymbolLike)) { + error(node.operand, Diagnostics.The_0_operator_cannot_be_applied_to_type_symbol, tokenToString(node.operator)); + } + if (node.operator === SyntaxKind.PlusToken) { + if (maybeTypeOfKindConsideringBaseConstraint(operandType, TypeFlags.BigIntLike)) { + error(node.operand, Diagnostics.Operator_0_cannot_be_applied_to_type_1, tokenToString(node.operator), typeToString(getBaseTypeOfLiteralType(operandType))); + } + return numberType; + } + return getUnaryResultType(operandType); + case SyntaxKind.ExclamationToken: + checkTruthinessOfType(operandType, node.operand); + const facts = getTypeFacts(operandType, TypeFacts.Truthy | TypeFacts.Falsy); + return facts === TypeFacts.Truthy ? falseType : + facts === TypeFacts.Falsy ? trueType : + booleanType; + case SyntaxKind.PlusPlusToken: + case SyntaxKind.MinusMinusToken: + const ok = checkArithmeticOperandType(node.operand, checkNonNullType(operandType, node.operand), Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type); + if (ok) { + // run check only if former checks succeeded to avoid reporting cascading errors + checkReferenceExpression( + node.operand, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access, + ); + } + return getUnaryResultType(operandType); + } + return errorType; + } + + function checkPostfixUnaryExpression(node: PostfixUnaryExpression): Type { + const operandType = checkExpression(node.operand); + if (operandType === silentNeverType) { + return silentNeverType; + } + const ok = checkArithmeticOperandType( + node.operand, + checkNonNullType(operandType, node.operand), + Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type, + ); + if (ok) { + // run check only if former checks succeeded to avoid reporting cascading errors + checkReferenceExpression( + node.operand, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access, + ); + } + return getUnaryResultType(operandType); + } + + function getUnaryResultType(operandType: Type): Type { + if (maybeTypeOfKind(operandType, TypeFlags.BigIntLike)) { + return isTypeAssignableToKind(operandType, TypeFlags.AnyOrUnknown) || maybeTypeOfKind(operandType, TypeFlags.NumberLike) + ? numberOrBigIntType + : bigintType; + } + // If it's not a bigint type, implicit coercion will result in a number + return numberType; + } + + function maybeTypeOfKindConsideringBaseConstraint(type: Type, kind: TypeFlags): boolean { + if (maybeTypeOfKind(type, kind)) { + return true; + } + + const baseConstraint = getBaseConstraintOrType(type); + return !!baseConstraint && maybeTypeOfKind(baseConstraint, kind); + } + + // Return true if type might be of the given kind. A union or intersection type might be of a given + // kind if at least one constituent type is of the given kind. + function maybeTypeOfKind(type: Type, kind: TypeFlags): boolean { + if (type.flags & kind) { + return true; + } + if (type.flags & TypeFlags.UnionOrIntersection) { + const types = (type as UnionOrIntersectionType).types; + for (const t of types) { + if (maybeTypeOfKind(t, kind)) { + return true; + } + } + } + return false; + } + + function isTypeAssignableToKind(source: Type, kind: TypeFlags, strict?: boolean): boolean { + if (source.flags & kind) { + return true; + } + if (strict && source.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Null)) { + return false; + } + return !!(kind & TypeFlags.NumberLike) && isTypeAssignableTo(source, numberType) || + !!(kind & TypeFlags.BigIntLike) && isTypeAssignableTo(source, bigintType) || + !!(kind & TypeFlags.StringLike) && isTypeAssignableTo(source, stringType) || + !!(kind & TypeFlags.BooleanLike) && isTypeAssignableTo(source, booleanType) || + !!(kind & TypeFlags.Void) && isTypeAssignableTo(source, voidType) || + !!(kind & TypeFlags.Never) && isTypeAssignableTo(source, neverType) || + !!(kind & TypeFlags.Null) && isTypeAssignableTo(source, nullType) || + !!(kind & TypeFlags.Undefined) && isTypeAssignableTo(source, undefinedType) || + !!(kind & TypeFlags.ESSymbol) && isTypeAssignableTo(source, esSymbolType) || + !!(kind & TypeFlags.NonPrimitive) && isTypeAssignableTo(source, nonPrimitiveType); + } + + function allTypesAssignableToKind(source: Type, kind: TypeFlags, strict?: boolean): boolean { + return source.flags & TypeFlags.Union ? + every((source as UnionType).types, subType => allTypesAssignableToKind(subType, kind, strict)) : + isTypeAssignableToKind(source, kind, strict); + } + + function isConstEnumObjectType(type: Type): boolean { + return !!(getObjectFlags(type) & ObjectFlags.Anonymous) && !!type.symbol && isConstEnumSymbol(type.symbol); + } + + function isConstEnumSymbol(symbol: Symbol): boolean { + return (symbol.flags & SymbolFlags.ConstEnum) !== 0; + } + + /** + * Get the type of the `[Symbol.hasInstance]` method of an object type. + */ + function getSymbolHasInstanceMethodOfObjectType(type: Type) { + const hasInstancePropertyName = getPropertyNameForKnownSymbolName("hasInstance"); + if (allTypesAssignableToKind(type, TypeFlags.NonPrimitive)) { + const hasInstanceProperty = getPropertyOfType(type, hasInstancePropertyName); + if (hasInstanceProperty) { + const hasInstancePropertyType = getTypeOfSymbol(hasInstanceProperty); + if (hasInstancePropertyType && getSignaturesOfType(hasInstancePropertyType, SignatureKind.Call).length !== 0) { + return hasInstancePropertyType; + } + } + } + } + + function checkInstanceOfExpression(left: Expression, right: Expression, leftType: Type, rightType: Type, checkMode?: CheckMode): Type { + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + + // TypeScript 1.0 spec (April 2014): 4.15.4 + // The instanceof operator requires the left operand to be of type Any, an object type, or a type parameter type, + // and the right operand to be of type Any, a subtype of the 'Function' interface type, or have a call or construct signature. + // The result is always of the Boolean primitive type. + // NOTE: do not raise error if leftType is unknown as related error was already reported + if ( + !isTypeAny(leftType) && + allTypesAssignableToKind(leftType, TypeFlags.Primitive) + ) { + error(left, Diagnostics.The_left_hand_side_of_an_instanceof_expression_must_be_of_type_any_an_object_type_or_a_type_parameter); + } + + Debug.assert(isInstanceOfExpression(left.parent)); + const signature = getResolvedSignature(left.parent, /*candidatesOutArray*/ undefined, checkMode); + if (signature === resolvingSignature) { + // CheckMode.SkipGenericFunctions is enabled and this is a call to a generic function that + // returns a function type. We defer checking and return silentNeverType. + return silentNeverType; + } + + // If rightType has a `[Symbol.hasInstance]` method that is not `(value: unknown) => boolean`, we + // must check the expression as if it were a call to `right[Symbol.hasInstance](left)`. The call to + // `getResolvedSignature`, below, will check that leftType is assignable to the type of the first + // parameter. + const returnType = getReturnTypeOfSignature(signature); + + // We also verify that the return type of the `[Symbol.hasInstance]` method is assignable to + // `boolean`. According to the spec, the runtime will actually perform `ToBoolean` on the result, + // but this is more type-safe. + checkTypeAssignableTo(returnType, booleanType, right, Diagnostics.An_object_s_Symbol_hasInstance_method_must_return_a_boolean_value_for_it_to_be_used_on_the_right_hand_side_of_an_instanceof_expression); + + return booleanType; + } + + function hasEmptyObjectIntersection(type: Type): boolean { + return someType(type, t => t === unknownEmptyObjectType || !!(t.flags & TypeFlags.Intersection) && isEmptyAnonymousObjectType(getBaseConstraintOrType(t))); + } + + function checkInExpression(left: Expression, right: Expression, leftType: Type, rightType: Type): Type { + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + if (isPrivateIdentifier(left)) { + if ( + languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators || + !useDefineForClassFields + ) { + checkExternalEmitHelpers(left, ExternalEmitHelpers.ClassPrivateFieldIn); + } + // Unlike in 'checkPrivateIdentifierExpression' we now have access to the RHS type + // which provides us with the opportunity to emit more detailed errors + if (!getNodeLinks(left).resolvedSymbol && getContainingClass(left)) { + const isUncheckedJS = isUncheckedJSSuggestion(left, rightType.symbol, /*excludeClasses*/ true); + reportNonexistentProperty(left, rightType, isUncheckedJS); + } + } + else { + // The type of the lef operand must be assignable to string, number, or symbol. + checkTypeAssignableTo(checkNonNullType(leftType, left), stringNumberSymbolType, left); + } + // The type of the right operand must be assignable to 'object'. + if (checkTypeAssignableTo(checkNonNullType(rightType, right), nonPrimitiveType, right)) { + // The {} type is assignable to the object type, yet {} might represent a primitive type. Here we + // detect and error on {} that results from narrowing the unknown type, as well as intersections + // that include {} (we know that the other types in such intersections are assignable to object + // since we already checked for that). + if (hasEmptyObjectIntersection(rightType)) { + error(right, Diagnostics.Type_0_may_represent_a_primitive_value_which_is_not_permitted_as_the_right_operand_of_the_in_operator, typeToString(rightType)); + } + } + // The result is always of the Boolean primitive type. + return booleanType; + } + + function checkObjectLiteralAssignment(node: ObjectLiteralExpression, sourceType: Type, rightIsThis?: boolean): Type { + const properties = node.properties; + if (strictNullChecks && properties.length === 0) { + return checkNonNullType(sourceType, node); + } + for (let i = 0; i < properties.length; i++) { + checkObjectLiteralDestructuringPropertyAssignment(node, sourceType, i, properties, rightIsThis); + } + return sourceType; + } + + /** Note: If property cannot be a SpreadAssignment, then allProperties does not need to be provided */ + function checkObjectLiteralDestructuringPropertyAssignment(node: ObjectLiteralExpression, objectLiteralType: Type, propertyIndex: number, allProperties?: NodeArray, rightIsThis = false) { + const properties = node.properties; + const property = properties[propertyIndex]; + if (property.kind === SyntaxKind.PropertyAssignment || property.kind === SyntaxKind.ShorthandPropertyAssignment) { + const name = property.name; + const exprType = getLiteralTypeFromPropertyName(name); + if (isTypeUsableAsPropertyName(exprType)) { + const text = getPropertyNameFromType(exprType); + const prop = getPropertyOfType(objectLiteralType, text); + if (prop) { + markPropertyAsReferenced(prop, property, rightIsThis); + checkPropertyAccessibility(property, /*isSuper*/ false, /*writing*/ true, objectLiteralType, prop); + } + } + const elementType = getIndexedAccessType(objectLiteralType, exprType, AccessFlags.ExpressionPosition, name); + const type = getFlowTypeOfDestructuring(property, elementType); + return checkDestructuringAssignment(property.kind === SyntaxKind.ShorthandPropertyAssignment ? property : property.initializer, type); + } + else if (property.kind === SyntaxKind.SpreadAssignment) { + if (propertyIndex < properties.length - 1) { + error(property, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); + } + else { + if (languageVersion < LanguageFeatureMinimumTarget.ObjectSpreadRest) { + checkExternalEmitHelpers(property, ExternalEmitHelpers.Rest); + } + const nonRestNames: PropertyName[] = []; + if (allProperties) { + for (const otherProperty of allProperties) { + if (!isSpreadAssignment(otherProperty)) { + nonRestNames.push(otherProperty.name); + } + } + } + const type = getRestType(objectLiteralType, nonRestNames, objectLiteralType.symbol); + checkGrammarForDisallowedTrailingComma(allProperties, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + return checkDestructuringAssignment(property.expression, type); + } + } + else { + error(property, Diagnostics.Property_assignment_expected); + } + } + + function checkArrayLiteralAssignment(node: ArrayLiteralExpression, sourceType: Type, checkMode?: CheckMode): Type { + const elements = node.elements; + if (languageVersion < LanguageFeatureMinimumTarget.DestructuringAssignment && compilerOptions.downlevelIteration) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Read); + } + // This elementType will be used if the specific property corresponding to this index is not + // present (aka the tuple element property). This call also checks that the parentType is in + // fact an iterable or array (depending on target language). + const possiblyOutOfBoundsType = checkIteratedTypeOrElementType(IterationUse.Destructuring | IterationUse.PossiblyOutOfBounds, sourceType, undefinedType, node) || errorType; + let inBoundsType: Type | undefined = compilerOptions.noUncheckedIndexedAccess ? undefined : possiblyOutOfBoundsType; + for (let i = 0; i < elements.length; i++) { + let type = possiblyOutOfBoundsType; + if (node.elements[i].kind === SyntaxKind.SpreadElement) { + type = inBoundsType = inBoundsType ?? (checkIteratedTypeOrElementType(IterationUse.Destructuring, sourceType, undefinedType, node) || errorType); + } + checkArrayLiteralDestructuringElementAssignment(node, sourceType, i, type, checkMode); + } + return sourceType; + } + + function checkArrayLiteralDestructuringElementAssignment(node: ArrayLiteralExpression, sourceType: Type, elementIndex: number, elementType: Type, checkMode?: CheckMode) { + const elements = node.elements; + const element = elements[elementIndex]; + if (element.kind !== SyntaxKind.OmittedExpression) { + if (element.kind !== SyntaxKind.SpreadElement) { + const indexType = getNumberLiteralType(elementIndex); + if (isArrayLikeType(sourceType)) { + // We create a synthetic expression so that getIndexedAccessType doesn't get confused + // when the element is a SyntaxKind.ElementAccessExpression. + const accessFlags = AccessFlags.ExpressionPosition | (hasDefaultValue(element) ? AccessFlags.NoTupleBoundsCheck : 0); + const elementType = getIndexedAccessTypeOrUndefined(sourceType, indexType, accessFlags, createSyntheticExpression(element, indexType)) || errorType; + const assignedType = hasDefaultValue(element) ? getTypeWithFacts(elementType, TypeFacts.NEUndefined) : elementType; + const type = getFlowTypeOfDestructuring(element, assignedType); + return checkDestructuringAssignment(element, type, checkMode); + } + return checkDestructuringAssignment(element, elementType, checkMode); + } + if (elementIndex < elements.length - 1) { + error(element, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); + } + else { + const restExpression = (element as SpreadElement).expression; + if (restExpression.kind === SyntaxKind.BinaryExpression && (restExpression as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) { + error((restExpression as BinaryExpression).operatorToken, Diagnostics.A_rest_element_cannot_have_an_initializer); + } + else { + checkGrammarForDisallowedTrailingComma(node.elements, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + const type = everyType(sourceType, isTupleType) ? + mapType(sourceType, t => sliceTupleType(t as TupleTypeReference, elementIndex)) : + createArrayType(elementType); + return checkDestructuringAssignment(restExpression, type, checkMode); + } + } + } + return undefined; + } + + function checkDestructuringAssignment(exprOrAssignment: Expression | ShorthandPropertyAssignment, sourceType: Type, checkMode?: CheckMode, rightIsThis?: boolean): Type { + let target: Expression; + if (exprOrAssignment.kind === SyntaxKind.ShorthandPropertyAssignment) { + const prop = exprOrAssignment as ShorthandPropertyAssignment; + if (prop.objectAssignmentInitializer) { + // In strict null checking mode, if a default value of a non-undefined type is specified, remove + // undefined from the final type. + if ( + strictNullChecks && + !(hasTypeFacts(checkExpression(prop.objectAssignmentInitializer), TypeFacts.IsUndefined)) + ) { + sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined); + } + checkBinaryLikeExpression(prop.name, prop.equalsToken!, prop.objectAssignmentInitializer, checkMode); + } + target = (exprOrAssignment as ShorthandPropertyAssignment).name; + } + else { + target = exprOrAssignment; + } + + if (target.kind === SyntaxKind.BinaryExpression && (target as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) { + checkBinaryExpression(target as BinaryExpression, checkMode); + target = (target as BinaryExpression).left; + // A default value is specified, so remove undefined from the final type. + if (strictNullChecks) { + sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined); + } + } + if (target.kind === SyntaxKind.ObjectLiteralExpression) { + return checkObjectLiteralAssignment(target as ObjectLiteralExpression, sourceType, rightIsThis); + } + if (target.kind === SyntaxKind.ArrayLiteralExpression) { + return checkArrayLiteralAssignment(target as ArrayLiteralExpression, sourceType, checkMode); + } + return checkReferenceAssignment(target, sourceType, checkMode); + } + + function checkReferenceAssignment(target: Expression, sourceType: Type, checkMode?: CheckMode): Type { + const targetType = checkExpression(target, checkMode); + const error = target.parent.kind === SyntaxKind.SpreadAssignment ? + Diagnostics.The_target_of_an_object_rest_assignment_must_be_a_variable_or_a_property_access : + Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access; + const optionalError = target.parent.kind === SyntaxKind.SpreadAssignment ? + Diagnostics.The_target_of_an_object_rest_assignment_may_not_be_an_optional_property_access : + Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access; + if (checkReferenceExpression(target, error, optionalError)) { + checkTypeAssignableToAndOptionallyElaborate(sourceType, targetType, target, target); + } + if (isPrivateIdentifierPropertyAccessExpression(target)) { + // NOTE: we do not limit this to LanguageFeatureTargets.PrivateNames as some other feature downleveling still requires this. + checkExternalEmitHelpers(target.parent, ExternalEmitHelpers.ClassPrivateFieldSet); + } + return sourceType; + } + + /** + * This is a *shallow* check: An expression is side-effect-free if the + * evaluation of the expression *itself* cannot produce side effects. + * For example, x++ / 3 is side-effect free because the / operator + * does not have side effects. + * The intent is to "smell test" an expression for correctness in positions where + * its value is discarded (e.g. the left side of the comma operator). + */ + function isSideEffectFree(node: Node): boolean { + node = skipParentheses(node); + switch (node.kind) { + case SyntaxKind.Identifier: + case SyntaxKind.StringLiteral: + case SyntaxKind.RegularExpressionLiteral: + case SyntaxKind.TaggedTemplateExpression: + case SyntaxKind.TemplateExpression: + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.NumericLiteral: + case SyntaxKind.BigIntLiteral: + case SyntaxKind.TrueKeyword: + case SyntaxKind.FalseKeyword: + case SyntaxKind.NullKeyword: + case SyntaxKind.UndefinedKeyword: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ClassExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.ArrayLiteralExpression: + case SyntaxKind.ObjectLiteralExpression: + case SyntaxKind.TypeOfExpression: + case SyntaxKind.NonNullExpression: + case SyntaxKind.JsxSelfClosingElement: + case SyntaxKind.JsxElement: + return true; + + case SyntaxKind.ConditionalExpression: + return isSideEffectFree((node as ConditionalExpression).whenTrue) && + isSideEffectFree((node as ConditionalExpression).whenFalse); + + case SyntaxKind.BinaryExpression: + if (isAssignmentOperator((node as BinaryExpression).operatorToken.kind)) { + return false; + } + return isSideEffectFree((node as BinaryExpression).left) && + isSideEffectFree((node as BinaryExpression).right); + + case SyntaxKind.PrefixUnaryExpression: + case SyntaxKind.PostfixUnaryExpression: + // Unary operators ~, !, +, and - have no side effects. + // The rest do. + switch ((node as PrefixUnaryExpression).operator) { + case SyntaxKind.ExclamationToken: + case SyntaxKind.PlusToken: + case SyntaxKind.MinusToken: + case SyntaxKind.TildeToken: + return true; + } + return false; + + // Some forms listed here for clarity + case SyntaxKind.VoidExpression: // Explicit opt-out + case SyntaxKind.TypeAssertionExpression: // Not SEF, but can produce useful type warnings + case SyntaxKind.AsExpression: // Not SEF, but can produce useful type warnings + default: + return false; + } + } + + function isTypeEqualityComparableTo(source: Type, target: Type) { + return (target.flags & TypeFlags.Nullable) !== 0 || isTypeComparableTo(source, target); + } + + function createCheckBinaryExpression() { + interface WorkArea { + readonly checkMode: CheckMode | undefined; + skip: boolean; + stackIndex: number; + /** + * Holds the types from the left-side of an expression from [0..stackIndex]. + * Holds the type of the result at stackIndex+1. This allows us to reuse existing stack entries + * and avoid storing an extra property on the object (i.e., `lastResult`). + */ + typeStack: (Type | undefined)[]; + } + + const trampoline = createBinaryExpressionTrampoline(onEnter, onLeft, onOperator, onRight, onExit, foldState); + + return (node: BinaryExpression, checkMode: CheckMode | undefined) => { + const result = trampoline(node, checkMode); + Debug.assertIsDefined(result); + return result; + }; + + function onEnter(node: BinaryExpression, state: WorkArea | undefined, checkMode: CheckMode | undefined) { + if (state) { + state.stackIndex++; + state.skip = false; + setLeftType(state, /*type*/ undefined); + setLastResult(state, /*type*/ undefined); + } + else { + state = { + checkMode, + skip: false, + stackIndex: 0, + typeStack: [undefined, undefined], + }; + } + + if (isInJSFile(node) && getAssignedExpandoInitializer(node)) { + state.skip = true; + setLastResult(state, checkExpression(node.right, checkMode)); + return state; + } + + checkGrammarNullishCoalesceWithLogicalExpression(node); + + const operator = node.operatorToken.kind; + if (operator === SyntaxKind.EqualsToken && (node.left.kind === SyntaxKind.ObjectLiteralExpression || node.left.kind === SyntaxKind.ArrayLiteralExpression)) { + state.skip = true; + setLastResult(state, checkDestructuringAssignment(node.left, checkExpression(node.right, checkMode), checkMode, node.right.kind === SyntaxKind.ThisKeyword)); + return state; + } + + return state; + } + + function onLeft(left: Expression, state: WorkArea, _node: BinaryExpression) { + if (!state.skip) { + return maybeCheckExpression(state, left); + } + } + + function onOperator(operatorToken: BinaryOperatorToken, state: WorkArea, node: BinaryExpression) { + if (!state.skip) { + const leftType = getLastResult(state); + Debug.assertIsDefined(leftType); + setLeftType(state, leftType); + setLastResult(state, /*type*/ undefined); + const operator = operatorToken.kind; + if (isLogicalOrCoalescingBinaryOperator(operator)) { + let parent = node.parent; + while (parent.kind === SyntaxKind.ParenthesizedExpression || isLogicalOrCoalescingBinaryExpression(parent)) { + parent = parent.parent; + } + if (operator === SyntaxKind.AmpersandAmpersandToken || isIfStatement(parent)) { + checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(node.left, leftType, isIfStatement(parent) ? parent.thenStatement : undefined); + } + checkTruthinessOfType(leftType, node.left); + } + } + } + + function onRight(right: Expression, state: WorkArea, _node: BinaryExpression) { + if (!state.skip) { + return maybeCheckExpression(state, right); + } + } + + function onExit(node: BinaryExpression, state: WorkArea): Type | undefined { + let result: Type | undefined; + if (state.skip) { + result = getLastResult(state); + } + else { + const leftType = getLeftType(state); + Debug.assertIsDefined(leftType); + + const rightType = getLastResult(state); + Debug.assertIsDefined(rightType); + + result = checkBinaryLikeExpressionWorker(node.left, node.operatorToken, node.right, leftType, rightType, state.checkMode, node); + } + + state.skip = false; + setLeftType(state, /*type*/ undefined); + setLastResult(state, /*type*/ undefined); + state.stackIndex--; + return result; + } + + function foldState(state: WorkArea, result: Type | undefined, _side: "left" | "right") { + setLastResult(state, result); + return state; + } + + function maybeCheckExpression(state: WorkArea, node: Expression): BinaryExpression | undefined { + if (isBinaryExpression(node)) { + return node; + } + setLastResult(state, checkExpression(node, state.checkMode)); + } + + function getLeftType(state: WorkArea) { + return state.typeStack[state.stackIndex]; + } + + function setLeftType(state: WorkArea, type: Type | undefined) { + state.typeStack[state.stackIndex] = type; + } + + function getLastResult(state: WorkArea) { + return state.typeStack[state.stackIndex + 1]; + } + + function setLastResult(state: WorkArea, type: Type | undefined) { + // To reduce overhead, reuse the next stack entry to store the + // last result. This avoids the overhead of an additional property + // on `WorkArea` and reuses empty stack entries as we walk back up + // the stack. + state.typeStack[state.stackIndex + 1] = type; + } + } + + function checkGrammarNullishCoalesceWithLogicalExpression(node: BinaryExpression) { + const { left, operatorToken, right } = node; + if (operatorToken.kind === SyntaxKind.QuestionQuestionToken) { + if (isBinaryExpression(left) && (left.operatorToken.kind === SyntaxKind.BarBarToken || left.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken)) { + grammarErrorOnNode(left, Diagnostics._0_and_1_operations_cannot_be_mixed_without_parentheses, tokenToString(left.operatorToken.kind), tokenToString(operatorToken.kind)); + } + if (isBinaryExpression(right) && (right.operatorToken.kind === SyntaxKind.BarBarToken || right.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken)) { + grammarErrorOnNode(right, Diagnostics._0_and_1_operations_cannot_be_mixed_without_parentheses, tokenToString(right.operatorToken.kind), tokenToString(operatorToken.kind)); + } + } + } + + // Note that this and `checkBinaryExpression` above should behave mostly the same, except this elides some + // expression-wide checks and does not use a work stack to fold nested binary expressions into the same callstack frame + function checkBinaryLikeExpression(left: Expression, operatorToken: BinaryOperatorToken, right: Expression, checkMode?: CheckMode, errorNode?: Node): Type { + const operator = operatorToken.kind; + if (operator === SyntaxKind.EqualsToken && (left.kind === SyntaxKind.ObjectLiteralExpression || left.kind === SyntaxKind.ArrayLiteralExpression)) { + return checkDestructuringAssignment(left, checkExpression(right, checkMode), checkMode, right.kind === SyntaxKind.ThisKeyword); + } + let leftType: Type; + if (isLogicalOrCoalescingBinaryOperator(operator)) { + leftType = checkTruthinessExpression(left, checkMode); + } + else { + leftType = checkExpression(left, checkMode); + } + + const rightType = checkExpression(right, checkMode); + return checkBinaryLikeExpressionWorker(left, operatorToken, right, leftType, rightType, checkMode, errorNode); + } + + function checkBinaryLikeExpressionWorker( + left: Expression, + operatorToken: BinaryOperatorToken, + right: Expression, + leftType: Type, + rightType: Type, + checkMode?: CheckMode, + errorNode?: Node, + ): Type { + const operator = operatorToken.kind; + switch (operator) { + case SyntaxKind.AsteriskToken: + case SyntaxKind.AsteriskAsteriskToken: + case SyntaxKind.AsteriskEqualsToken: + case SyntaxKind.AsteriskAsteriskEqualsToken: + case SyntaxKind.SlashToken: + case SyntaxKind.SlashEqualsToken: + case SyntaxKind.PercentToken: + case SyntaxKind.PercentEqualsToken: + case SyntaxKind.MinusToken: + case SyntaxKind.MinusEqualsToken: + case SyntaxKind.LessThanLessThanToken: + case SyntaxKind.LessThanLessThanEqualsToken: + case SyntaxKind.GreaterThanGreaterThanToken: + case SyntaxKind.GreaterThanGreaterThanEqualsToken: + case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: + case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken: + case SyntaxKind.BarToken: + case SyntaxKind.BarEqualsToken: + case SyntaxKind.CaretToken: + case SyntaxKind.CaretEqualsToken: + case SyntaxKind.AmpersandToken: + case SyntaxKind.AmpersandEqualsToken: + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + + leftType = checkNonNullType(leftType, left); + rightType = checkNonNullType(rightType, right); + + let suggestedOperator: PunctuationSyntaxKind | undefined; + // if a user tries to apply a bitwise operator to 2 boolean operands + // try and return them a helpful suggestion + if ( + (leftType.flags & TypeFlags.BooleanLike) && + (rightType.flags & TypeFlags.BooleanLike) && + (suggestedOperator = getSuggestedBooleanOperator(operatorToken.kind)) !== undefined + ) { + error(errorNode || operatorToken, Diagnostics.The_0_operator_is_not_allowed_for_boolean_types_Consider_using_1_instead, tokenToString(operatorToken.kind), tokenToString(suggestedOperator)); + return numberType; + } + else { + // otherwise just check each operand separately and report errors as normal + const leftOk = checkArithmeticOperandType(left, leftType, Diagnostics.The_left_hand_side_of_an_arithmetic_operation_must_be_of_type_any_number_bigint_or_an_enum_type, /*isAwaitValid*/ true); + const rightOk = checkArithmeticOperandType(right, rightType, Diagnostics.The_right_hand_side_of_an_arithmetic_operation_must_be_of_type_any_number_bigint_or_an_enum_type, /*isAwaitValid*/ true); + let resultType: Type; + // If both are any or unknown, allow operation; assume it will resolve to number + if ( + (isTypeAssignableToKind(leftType, TypeFlags.AnyOrUnknown) && isTypeAssignableToKind(rightType, TypeFlags.AnyOrUnknown)) || + // Or, if neither could be bigint, implicit coercion results in a number result + !(maybeTypeOfKind(leftType, TypeFlags.BigIntLike) || maybeTypeOfKind(rightType, TypeFlags.BigIntLike)) + ) { + resultType = numberType; + } + // At least one is assignable to bigint, so check that both are + else if (bothAreBigIntLike(leftType, rightType)) { + switch (operator) { + case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: + case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken: + reportOperatorError(); + break; + case SyntaxKind.AsteriskAsteriskToken: + case SyntaxKind.AsteriskAsteriskEqualsToken: + if (languageVersion < ScriptTarget.ES2016) { + error(errorNode, Diagnostics.Exponentiation_cannot_be_performed_on_bigint_values_unless_the_target_option_is_set_to_es2016_or_later); + } + } + resultType = bigintType; + } + // Exactly one of leftType/rightType is assignable to bigint + else { + reportOperatorError(bothAreBigIntLike); + resultType = errorType; + } + if (leftOk && rightOk) { + checkAssignmentOperator(resultType); + } + return resultType; + } + case SyntaxKind.PlusToken: + case SyntaxKind.PlusEqualsToken: + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + + if (!isTypeAssignableToKind(leftType, TypeFlags.StringLike) && !isTypeAssignableToKind(rightType, TypeFlags.StringLike)) { + leftType = checkNonNullType(leftType, left); + rightType = checkNonNullType(rightType, right); + } + + let resultType: Type | undefined; + if (isTypeAssignableToKind(leftType, TypeFlags.NumberLike, /*strict*/ true) && isTypeAssignableToKind(rightType, TypeFlags.NumberLike, /*strict*/ true)) { + // Operands of an enum type are treated as having the primitive type Number. + // If both operands are of the Number primitive type, the result is of the Number primitive type. + resultType = numberType; + } + else if (isTypeAssignableToKind(leftType, TypeFlags.BigIntLike, /*strict*/ true) && isTypeAssignableToKind(rightType, TypeFlags.BigIntLike, /*strict*/ true)) { + // If both operands are of the BigInt primitive type, the result is of the BigInt primitive type. + resultType = bigintType; + } + else if (isTypeAssignableToKind(leftType, TypeFlags.StringLike, /*strict*/ true) || isTypeAssignableToKind(rightType, TypeFlags.StringLike, /*strict*/ true)) { + // If one or both operands are of the String primitive type, the result is of the String primitive type. + resultType = stringType; + } + else if (isTypeAny(leftType) || isTypeAny(rightType)) { + // Otherwise, the result is of type Any. + // NOTE: unknown type here denotes error type. Old compiler treated this case as any type so do we. + resultType = isErrorType(leftType) || isErrorType(rightType) ? errorType : anyType; + } + + // Symbols are not allowed at all in arithmetic expressions + if (resultType && !checkForDisallowedESSymbolOperand(operator)) { + return resultType; + } + + if (!resultType) { + // Types that have a reasonably good chance of being a valid operand type. + // If both types have an awaited type of one of these, we'll assume the user + // might be missing an await without doing an exhaustive check that inserting + // await(s) will actually be a completely valid binary expression. + const closeEnoughKind = TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.AnyOrUnknown; + reportOperatorError((left, right) => + isTypeAssignableToKind(left, closeEnoughKind) && + isTypeAssignableToKind(right, closeEnoughKind) + ); + return anyType; + } + + if (operator === SyntaxKind.PlusEqualsToken) { + checkAssignmentOperator(resultType); + } + return resultType; + case SyntaxKind.LessThanToken: + case SyntaxKind.GreaterThanToken: + case SyntaxKind.LessThanEqualsToken: + case SyntaxKind.GreaterThanEqualsToken: + if (checkForDisallowedESSymbolOperand(operator)) { + leftType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(leftType, left)); + rightType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(rightType, right)); + reportOperatorErrorUnless((left, right) => { + if (isTypeAny(left) || isTypeAny(right)) { + return true; + } + const leftAssignableToNumber = isTypeAssignableTo(left, numberOrBigIntType); + const rightAssignableToNumber = isTypeAssignableTo(right, numberOrBigIntType); + return leftAssignableToNumber && rightAssignableToNumber || + !leftAssignableToNumber && !rightAssignableToNumber && areTypesComparable(left, right); + }); + } + return booleanType; + case SyntaxKind.EqualsEqualsToken: + case SyntaxKind.ExclamationEqualsToken: + case SyntaxKind.EqualsEqualsEqualsToken: + case SyntaxKind.ExclamationEqualsEqualsToken: + // We suppress errors in CheckMode.TypeOnly (meaning the invocation came from getTypeOfExpression). During + // control flow analysis it is possible for operands to temporarily have narrower types, and those narrower + // types may cause the operands to not be comparable. We don't want such errors reported (see #46475). + if (!(checkMode && checkMode & CheckMode.TypeOnly)) { + if ( + (isLiteralExpressionOfObject(left) || isLiteralExpressionOfObject(right)) && + // only report for === and !== in JS, not == or != + (!isInJSFile(left) || (operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken)) + ) { + const eqType = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken; + error(errorNode, Diagnostics.This_condition_will_always_return_0_since_JavaScript_compares_objects_by_reference_not_value, eqType ? "false" : "true"); + } + checkNaNEquality(errorNode, operator, left, right); + reportOperatorErrorUnless((left, right) => isTypeEqualityComparableTo(left, right) || isTypeEqualityComparableTo(right, left)); + } + return booleanType; + case SyntaxKind.InstanceOfKeyword: + return checkInstanceOfExpression(left, right, leftType, rightType, checkMode); + case SyntaxKind.InKeyword: + return checkInExpression(left, right, leftType, rightType); + case SyntaxKind.AmpersandAmpersandToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: { + const resultType = hasTypeFacts(leftType, TypeFacts.Truthy) ? + getUnionType([extractDefinitelyFalsyTypes(strictNullChecks ? leftType : getBaseTypeOfLiteralType(rightType)), rightType]) : + leftType; + if (operator === SyntaxKind.AmpersandAmpersandEqualsToken) { + checkAssignmentOperator(rightType); + } + return resultType; + } + case SyntaxKind.BarBarToken: + case SyntaxKind.BarBarEqualsToken: { + const resultType = hasTypeFacts(leftType, TypeFacts.Falsy) ? + getUnionType([getNonNullableType(removeDefinitelyFalsyTypes(leftType)), rightType], UnionReduction.Subtype) : + leftType; + if (operator === SyntaxKind.BarBarEqualsToken) { + checkAssignmentOperator(rightType); + } + return resultType; + } + case SyntaxKind.QuestionQuestionToken: + case SyntaxKind.QuestionQuestionEqualsToken: { + const resultType = hasTypeFacts(leftType, TypeFacts.EQUndefinedOrNull) ? + getUnionType([getNonNullableType(leftType), rightType], UnionReduction.Subtype) : + leftType; + if (operator === SyntaxKind.QuestionQuestionEqualsToken) { + checkAssignmentOperator(rightType); + } + return resultType; + } + case SyntaxKind.EqualsToken: + const declKind = isBinaryExpression(left.parent) ? getAssignmentDeclarationKind(left.parent) : AssignmentDeclarationKind.None; + checkAssignmentDeclaration(declKind, rightType); + if (isAssignmentDeclaration(declKind)) { + if ( + !(rightType.flags & TypeFlags.Object) || + declKind !== AssignmentDeclarationKind.ModuleExports && + declKind !== AssignmentDeclarationKind.Prototype && + !isEmptyObjectType(rightType) && + !isFunctionObjectType(rightType as ObjectType) && + !(getObjectFlags(rightType) & ObjectFlags.Class) + ) { + // don't check assignability of module.exports=, C.prototype=, or expando types because they will necessarily be incomplete + checkAssignmentOperator(rightType); + } + return leftType; + } + else { + checkAssignmentOperator(rightType); + return rightType; + } + case SyntaxKind.CommaToken: + if (!compilerOptions.allowUnreachableCode && isSideEffectFree(left) && !isIndirectCall(left.parent as BinaryExpression)) { + const sf = getSourceFileOfNode(left); + const sourceText = sf.text; + const start = skipTrivia(sourceText, left.pos); + const isInDiag2657 = sf.parseDiagnostics.some(diag => { + if (diag.code !== Diagnostics.JSX_expressions_must_have_one_parent_element.code) return false; + return textSpanContainsPosition(diag, start); + }); + if (!isInDiag2657) error(left, Diagnostics.Left_side_of_comma_operator_is_unused_and_has_no_side_effects); + } + return rightType; + + default: + return Debug.fail(); + } + + function bothAreBigIntLike(left: Type, right: Type): boolean { + return isTypeAssignableToKind(left, TypeFlags.BigIntLike) && isTypeAssignableToKind(right, TypeFlags.BigIntLike); + } + + function checkAssignmentDeclaration(kind: AssignmentDeclarationKind, rightType: Type) { + if (kind === AssignmentDeclarationKind.ModuleExports) { + for (const prop of getPropertiesOfObjectType(rightType)) { + const propType = getTypeOfSymbol(prop); + if (propType.symbol && propType.symbol.flags & SymbolFlags.Class) { + const name = prop.escapedName; + const symbol = resolveName(prop.valueDeclaration, name, SymbolFlags.Type, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (symbol?.declarations && symbol.declarations.some(isJSDocTypedefTag)) { + addDuplicateDeclarationErrorsForSymbols(symbol, Diagnostics.Duplicate_identifier_0, unescapeLeadingUnderscores(name), prop); + addDuplicateDeclarationErrorsForSymbols(prop, Diagnostics.Duplicate_identifier_0, unescapeLeadingUnderscores(name), symbol); + } + } + } + } + } + + // Return true for "indirect calls", (i.e. `(0, x.f)(...)` or `(0, eval)(...)`), which prevents passing `this`. + function isIndirectCall(node: BinaryExpression): boolean { + return node.parent.kind === SyntaxKind.ParenthesizedExpression && + isNumericLiteral(node.left) && + node.left.text === "0" && + (isCallExpression(node.parent.parent) && node.parent.parent.expression === node.parent || node.parent.parent.kind === SyntaxKind.TaggedTemplateExpression) && + // special-case for "eval" because it's the only non-access case where an indirect call actually affects behavior. + (isAccessExpression(node.right) || isIdentifier(node.right) && node.right.escapedText === "eval"); + } + + // Return true if there was no error, false if there was an error. + function checkForDisallowedESSymbolOperand(operator: PunctuationSyntaxKind): boolean { + const offendingSymbolOperand = maybeTypeOfKindConsideringBaseConstraint(leftType, TypeFlags.ESSymbolLike) ? left : + maybeTypeOfKindConsideringBaseConstraint(rightType, TypeFlags.ESSymbolLike) ? right : + undefined; + + if (offendingSymbolOperand) { + error(offendingSymbolOperand, Diagnostics.The_0_operator_cannot_be_applied_to_type_symbol, tokenToString(operator)); + return false; + } + + return true; + } + + function getSuggestedBooleanOperator(operator: SyntaxKind): PunctuationSyntaxKind | undefined { + switch (operator) { + case SyntaxKind.BarToken: + case SyntaxKind.BarEqualsToken: + return SyntaxKind.BarBarToken; + case SyntaxKind.CaretToken: + case SyntaxKind.CaretEqualsToken: + return SyntaxKind.ExclamationEqualsEqualsToken; + case SyntaxKind.AmpersandToken: + case SyntaxKind.AmpersandEqualsToken: + return SyntaxKind.AmpersandAmpersandToken; + default: + return undefined; + } + } + + function checkAssignmentOperator(valueType: Type): void { + if (isAssignmentOperator(operator)) { + addLazyDiagnostic(checkAssignmentOperatorWorker); + } + + function checkAssignmentOperatorWorker() { + let assigneeType = leftType; + + // getters can be a subtype of setters, so to check for assignability we use the setter's type instead + if (isCompoundAssignment(operatorToken.kind) && left.kind === SyntaxKind.PropertyAccessExpression) { + assigneeType = checkPropertyAccessExpression(left as PropertyAccessExpression, /*checkMode*/ undefined, /*writeOnly*/ true); + } + + // TypeScript 1.0 spec (April 2014): 4.17 + // An assignment of the form + // VarExpr = ValueExpr + // requires VarExpr to be classified as a reference + // A compound assignment furthermore requires VarExpr to be classified as a reference (section 4.1) + // and the type of the non-compound operation to be assignable to the type of VarExpr. + + if (checkReferenceExpression(left, Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access, Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access)) { + let headMessage: DiagnosticMessage | undefined; + if (exactOptionalPropertyTypes && isPropertyAccessExpression(left) && maybeTypeOfKind(valueType, TypeFlags.Undefined)) { + const target = getTypeOfPropertyOfType(getTypeOfExpression(left.expression), left.name.escapedText); + if (isExactOptionalPropertyMismatch(valueType, target)) { + headMessage = Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target; + } + } + // to avoid cascading errors check assignability only if 'isReference' check succeeded and no errors were reported + checkTypeAssignableToAndOptionallyElaborate(valueType, assigneeType, left, right, headMessage); + } + } + } + + function isAssignmentDeclaration(kind: AssignmentDeclarationKind) { + switch (kind) { + case AssignmentDeclarationKind.ModuleExports: + return true; + case AssignmentDeclarationKind.ExportsProperty: + case AssignmentDeclarationKind.Property: + case AssignmentDeclarationKind.Prototype: + case AssignmentDeclarationKind.PrototypeProperty: + case AssignmentDeclarationKind.ThisProperty: + const symbol = getSymbolOfNode(left); + const init = getAssignedExpandoInitializer(right); + return !!init && isObjectLiteralExpression(init) && + !!symbol?.exports?.size; + default: + return false; + } + } + + /** + * Returns true if an error is reported + */ + function reportOperatorErrorUnless(typesAreCompatible: (left: Type, right: Type) => boolean): boolean { + if (!typesAreCompatible(leftType, rightType)) { + reportOperatorError(typesAreCompatible); + return true; + } + return false; + } + + function reportOperatorError(isRelated?: (left: Type, right: Type) => boolean) { + let wouldWorkWithAwait = false; + const errNode = errorNode || operatorToken; + if (isRelated) { + const awaitedLeftType = getAwaitedTypeNoAlias(leftType); + const awaitedRightType = getAwaitedTypeNoAlias(rightType); + wouldWorkWithAwait = !(awaitedLeftType === leftType && awaitedRightType === rightType) + && !!(awaitedLeftType && awaitedRightType) + && isRelated(awaitedLeftType, awaitedRightType); + } + + let effectiveLeft = leftType; + let effectiveRight = rightType; + if (!wouldWorkWithAwait && isRelated) { + [effectiveLeft, effectiveRight] = getBaseTypesIfUnrelated(leftType, rightType, isRelated); + } + const [leftStr, rightStr] = getTypeNamesForErrorDisplay(effectiveLeft, effectiveRight); + if (!tryGiveBetterPrimaryError(errNode, wouldWorkWithAwait, leftStr, rightStr)) { + errorAndMaybeSuggestAwait( + errNode, + wouldWorkWithAwait, + Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2, + tokenToString(operatorToken.kind), + leftStr, + rightStr, + ); + } + } + + function tryGiveBetterPrimaryError(errNode: Node, maybeMissingAwait: boolean, leftStr: string, rightStr: string) { + switch (operatorToken.kind) { + case SyntaxKind.EqualsEqualsEqualsToken: + case SyntaxKind.EqualsEqualsToken: + case SyntaxKind.ExclamationEqualsEqualsToken: + case SyntaxKind.ExclamationEqualsToken: + return errorAndMaybeSuggestAwait( + errNode, + maybeMissingAwait, + Diagnostics.This_comparison_appears_to_be_unintentional_because_the_types_0_and_1_have_no_overlap, + leftStr, + rightStr, + ); + default: + return undefined; + } + } + + function checkNaNEquality(errorNode: Node | undefined, operator: SyntaxKind, left: Expression, right: Expression) { + const isLeftNaN = isGlobalNaN(skipParentheses(left)); + const isRightNaN = isGlobalNaN(skipParentheses(right)); + if (isLeftNaN || isRightNaN) { + const err = error(errorNode, Diagnostics.This_condition_will_always_return_0, tokenToString(operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.EqualsEqualsToken ? SyntaxKind.FalseKeyword : SyntaxKind.TrueKeyword)); + if (isLeftNaN && isRightNaN) return; + const operatorString = operator === SyntaxKind.ExclamationEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken ? tokenToString(SyntaxKind.ExclamationToken) : ""; + const location = isLeftNaN ? right : left; + const expression = skipParentheses(location); + addRelatedInfo(err, createDiagnosticForNode(location, Diagnostics.Did_you_mean_0, `${operatorString}Number.isNaN(${isEntityNameExpression(expression) ? entityNameToString(expression) : "..."})`)); + } + } + + function isGlobalNaN(expr: Expression): boolean { + if (isIdentifier(expr) && expr.escapedText === "NaN") { + const globalNaNSymbol = getGlobalNaNSymbol(); + return !!globalNaNSymbol && globalNaNSymbol === getResolvedSymbol(expr); + } + return false; + } + } + + function getBaseTypesIfUnrelated(leftType: Type, rightType: Type, isRelated: (left: Type, right: Type) => boolean): [Type, Type] { + let effectiveLeft = leftType; + let effectiveRight = rightType; + const leftBase = getBaseTypeOfLiteralType(leftType); + const rightBase = getBaseTypeOfLiteralType(rightType); + if (!isRelated(leftBase, rightBase)) { + effectiveLeft = leftBase; + effectiveRight = rightBase; + } + return [effectiveLeft, effectiveRight]; + } + + function checkYieldExpression(node: YieldExpression): Type { + addLazyDiagnostic(checkYieldExpressionGrammar); + + const func = getContainingFunction(node); + if (!func) return anyType; + const functionFlags = getFunctionFlags(func); + + if (!(functionFlags & FunctionFlags.Generator)) { + // If the user's code is syntactically correct, the func should always have a star. After all, we are in a yield context. + return anyType; + } + + const isAsync = (functionFlags & FunctionFlags.Async) !== 0; + if (node.asteriskToken) { + // Async generator functions prior to ES2018 require the __await, __asyncDelegator, + // and __asyncValues helpers + if (isAsync && languageVersion < LanguageFeatureMinimumTarget.AsyncGenerators) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.AsyncDelegatorIncludes); + } + + // Generator functions prior to ES2015 require the __values helper + if (!isAsync && languageVersion < LanguageFeatureMinimumTarget.Generators && compilerOptions.downlevelIteration) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Values); + } + } + + // There is no point in doing an assignability check if the function + // has no explicit return type because the return type is directly computed + // from the yield expressions. + let returnType = getReturnTypeFromAnnotation(func); + if (returnType && returnType.flags & TypeFlags.Union) { + returnType = filterType(returnType, t => checkGeneratorInstantiationAssignabilityToReturnType(t, functionFlags, /*errorNode*/ undefined)); + } + const iterationTypes = returnType && getIterationTypesOfGeneratorFunctionReturnType(returnType, isAsync); + const signatureYieldType = iterationTypes && iterationTypes.yieldType || anyType; + const signatureNextType = iterationTypes && iterationTypes.nextType || anyType; + const resolvedSignatureNextType = isAsync ? getAwaitedType(signatureNextType) || anyType : signatureNextType; + const yieldExpressionType = node.expression ? checkExpression(node.expression) : undefinedWideningType; + const yieldedType = getYieldedTypeOfYieldExpression(node, yieldExpressionType, resolvedSignatureNextType, isAsync); + if (returnType && yieldedType) { + checkTypeAssignableToAndOptionallyElaborate(yieldedType, signatureYieldType, node.expression || node, node.expression); + } + + if (node.asteriskToken) { + const use = isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar; + return getIterationTypeOfIterable(use, IterationTypeKind.Return, yieldExpressionType, node.expression) + || anyType; + } + else if (returnType) { + return getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Next, returnType, isAsync) + || anyType; + } + let type = getContextualIterationType(IterationTypeKind.Next, func); + if (!type) { + type = anyType; + addLazyDiagnostic(() => { + if (noImplicitAny && !expressionResultIsUnused(node)) { + const contextualType = getContextualType(node, /*contextFlags*/ undefined); + if (!contextualType || isTypeAny(contextualType)) { + error(node, Diagnostics.yield_expression_implicitly_results_in_an_any_type_because_its_containing_generator_lacks_a_return_type_annotation); + } + } + }); + } + return type; + + function checkYieldExpressionGrammar() { + if (!(node.flags & NodeFlags.YieldContext)) { + grammarErrorOnFirstToken(node, Diagnostics.A_yield_expression_is_only_allowed_in_a_generator_body); + } + + if (isInParameterInitializerBeforeContainingFunction(node)) { + error(node, Diagnostics.yield_expressions_cannot_be_used_in_a_parameter_initializer); + } + } + } + + function checkConditionalExpression(node: ConditionalExpression, checkMode?: CheckMode): Type { + const type = checkTruthinessExpression(node.condition, checkMode); + checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(node.condition, type, node.whenTrue); + const type1 = checkExpression(node.whenTrue, checkMode); + const type2 = checkExpression(node.whenFalse, checkMode); + return getUnionType([type1, type2], UnionReduction.Subtype); + } + + function isTemplateLiteralContext(node: Node): boolean { + const parent = node.parent; + return isParenthesizedExpression(parent) && isTemplateLiteralContext(parent) || + isElementAccessExpression(parent) && parent.argumentExpression === node; + } + + function checkTemplateExpression(node: TemplateExpression): Type { + const texts = [node.head.text]; + const types = []; + for (const span of node.templateSpans) { + const type = checkExpression(span.expression); + if (maybeTypeOfKindConsideringBaseConstraint(type, TypeFlags.ESSymbolLike)) { + error(span.expression, Diagnostics.Implicit_conversion_of_a_symbol_to_a_string_will_fail_at_runtime_Consider_wrapping_this_expression_in_String); + } + texts.push(span.literal.text); + types.push(isTypeAssignableTo(type, templateConstraintType) ? type : stringType); + } + const evaluated = node.parent.kind !== SyntaxKind.TaggedTemplateExpression && evaluate(node).value; + if (evaluated) { + return getFreshTypeOfLiteralType(getStringLiteralType(evaluated)); + } + if (isConstContext(node) || isTemplateLiteralContext(node) || someType(getContextualType(node, /*contextFlags*/ undefined) || unknownType, isTemplateLiteralContextualType)) { + return getTemplateLiteralType(texts, types); + } + return stringType; + } + + function isTemplateLiteralContextualType(type: Type): boolean { + return !!(type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral) || + type.flags & TypeFlags.InstantiableNonPrimitive && maybeTypeOfKind(getBaseConstraintOfType(type) || unknownType, TypeFlags.StringLike)); + } + + function getContextNode(node: Expression): Expression { + if (isJsxAttributes(node) && !isJsxSelfClosingElement(node.parent)) { + return node.parent.parent; // Needs to be the root JsxElement, so it encompasses the attributes _and_ the children (which are essentially part of the attributes) + } + return node; + } + + function checkExpressionWithContextualType(node: Expression, contextualType: Type, inferenceContext: InferenceContext | undefined, checkMode: CheckMode): Type { + const contextNode = getContextNode(node); + pushContextualType(contextNode, contextualType, /*isCache*/ false); + pushInferenceContext(contextNode, inferenceContext); + const type = checkExpression(node, checkMode | CheckMode.Contextual | (inferenceContext ? CheckMode.Inferential : 0)); + // In CheckMode.Inferential we collect intra-expression inference sites to process before fixing any type + // parameters. This information is no longer needed after the call to checkExpression. + if (inferenceContext && inferenceContext.intraExpressionInferenceSites) { + inferenceContext.intraExpressionInferenceSites = undefined; + } + // We strip literal freshness when an appropriate contextual type is present such that contextually typed + // literals always preserve their literal types (otherwise they might widen during type inference). An alternative + // here would be to not mark contextually typed literals as fresh in the first place. + const result = maybeTypeOfKind(type, TypeFlags.Literal) && isLiteralOfContextualType(type, instantiateContextualType(contextualType, node, /*contextFlags*/ undefined)) ? + getRegularTypeOfLiteralType(type) : type; + popInferenceContext(); + popContextualType(); + return result; + } + + function checkExpressionCached(node: Expression | QualifiedName, checkMode?: CheckMode): Type { + if (checkMode) { + return checkExpression(node, checkMode); + } + const links = getNodeLinks(node); + if (!links.resolvedType) { + // When computing a type that we're going to cache, we need to ignore any ongoing control flow + // analysis because variables may have transient types in indeterminable states. Moving flowLoopStart + // to the top of the stack ensures all transient types are computed from a known point. + const saveFlowLoopStart = flowLoopStart; + const saveFlowTypeCache = flowTypeCache; + flowLoopStart = flowLoopCount; + flowTypeCache = undefined; + links.resolvedType = checkExpression(node, checkMode); + flowTypeCache = saveFlowTypeCache; + flowLoopStart = saveFlowLoopStart; + } + return links.resolvedType; + } + + function isTypeAssertion(node: Expression) { + node = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + return node.kind === SyntaxKind.TypeAssertionExpression || + node.kind === SyntaxKind.AsExpression || + isJSDocTypeAssertion(node); + } + + function checkDeclarationInitializer( + declaration: HasExpressionInitializer, + checkMode: CheckMode, + contextualType?: Type | undefined, + ) { + const initializer = getEffectiveInitializer(declaration)!; + if (isInJSFile(declaration)) { + const typeNode = tryGetJSDocSatisfiesTypeNode(declaration); + if (typeNode) { + return checkSatisfiesExpressionWorker(initializer, typeNode, checkMode); + } + } + const type = getQuickTypeOfExpression(initializer) || + (contextualType ? + checkExpressionWithContextualType(initializer, contextualType, /*inferenceContext*/ undefined, checkMode || CheckMode.Normal) + : checkExpressionCached(initializer, checkMode)); + return isParameter(declaration) && declaration.name.kind === SyntaxKind.ArrayBindingPattern && + isTupleType(type) && !(type.target.combinedFlags & ElementFlags.Variable) && getTypeReferenceArity(type) < declaration.name.elements.length ? + padTupleType(type, declaration.name) : type; + } + + function padTupleType(type: TupleTypeReference, pattern: ArrayBindingPattern) { + const patternElements = pattern.elements; + const elementTypes = getElementTypes(type).slice(); + const elementFlags = type.target.elementFlags.slice(); + for (let i = getTypeReferenceArity(type); i < patternElements.length; i++) { + const e = patternElements[i]; + if (i < patternElements.length - 1 || !(e.kind === SyntaxKind.BindingElement && e.dotDotDotToken)) { + elementTypes.push(!isOmittedExpression(e) && hasDefaultValue(e) ? getTypeFromBindingElement(e, /*includePatternInType*/ false, /*reportErrors*/ false) : anyType); + elementFlags.push(ElementFlags.Optional); + if (!isOmittedExpression(e) && !hasDefaultValue(e)) { + reportImplicitAny(e, anyType); + } + } + } + return createTupleType(elementTypes, elementFlags, type.target.readonly); + } + + function widenTypeInferredFromInitializer(declaration: HasExpressionInitializer, type: Type) { + const widened = getCombinedNodeFlagsCached(declaration) & NodeFlags.Constant || isDeclarationReadonly(declaration) ? type : getWidenedLiteralType(type); + if (isInJSFile(declaration)) { + if (isEmptyLiteralType(widened)) { + reportImplicitAny(declaration, anyType); + return anyType; + } + else if (isEmptyArrayLiteralType(widened)) { + reportImplicitAny(declaration, anyArrayType); + return anyArrayType; + } + } + return widened; + } + + function isLiteralOfContextualType(candidateType: Type, contextualType: Type | undefined): boolean { + if (contextualType) { + if (contextualType.flags & TypeFlags.UnionOrIntersection) { + const types = (contextualType as UnionType).types; + return some(types, t => isLiteralOfContextualType(candidateType, t)); + } + if (contextualType.flags & TypeFlags.InstantiableNonPrimitive) { + // If the contextual type is a type variable constrained to a primitive type, consider + // this a literal context for literals of that primitive type. For example, given a + // type parameter 'T extends string', infer string literal types for T. + const constraint = getBaseConstraintOfType(contextualType) || unknownType; + return maybeTypeOfKind(constraint, TypeFlags.String) && maybeTypeOfKind(candidateType, TypeFlags.StringLiteral) || + maybeTypeOfKind(constraint, TypeFlags.Number) && maybeTypeOfKind(candidateType, TypeFlags.NumberLiteral) || + maybeTypeOfKind(constraint, TypeFlags.BigInt) && maybeTypeOfKind(candidateType, TypeFlags.BigIntLiteral) || + maybeTypeOfKind(constraint, TypeFlags.ESSymbol) && maybeTypeOfKind(candidateType, TypeFlags.UniqueESSymbol) || + isLiteralOfContextualType(candidateType, constraint); + } + // If the contextual type is a literal of a particular primitive type, we consider this a + // literal context for all literals of that primitive type. + return !!(contextualType.flags & (TypeFlags.StringLiteral | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && maybeTypeOfKind(candidateType, TypeFlags.StringLiteral) || + contextualType.flags & TypeFlags.NumberLiteral && maybeTypeOfKind(candidateType, TypeFlags.NumberLiteral) || + contextualType.flags & TypeFlags.BigIntLiteral && maybeTypeOfKind(candidateType, TypeFlags.BigIntLiteral) || + contextualType.flags & TypeFlags.BooleanLiteral && maybeTypeOfKind(candidateType, TypeFlags.BooleanLiteral) || + contextualType.flags & TypeFlags.UniqueESSymbol && maybeTypeOfKind(candidateType, TypeFlags.UniqueESSymbol)); + } + return false; + } + + function isConstContext(node: Expression): boolean { + const parent = node.parent; + return isAssertionExpression(parent) && isConstTypeReference(parent.type) || + isJSDocTypeAssertion(parent) && isConstTypeReference(getJSDocTypeAssertionType(parent)) || + isValidConstAssertionArgument(node) && isConstTypeVariable(getContextualType(node, ContextFlags.None)) || + (isParenthesizedExpression(parent) || isArrayLiteralExpression(parent) || isSpreadElement(parent)) && isConstContext(parent) || + (isPropertyAssignment(parent) || isShorthandPropertyAssignment(parent) || isTemplateSpan(parent)) && isConstContext(parent.parent); + } + + function checkExpressionForMutableLocation(node: Expression, checkMode: CheckMode | undefined, forceTuple?: boolean): Type { + const type = checkExpression(node, checkMode, forceTuple); + return isConstContext(node) || isCommonJsExportedExpression(node) ? getRegularTypeOfLiteralType(type) : + isTypeAssertion(node) ? type : + getWidenedLiteralLikeTypeForContextualType(type, instantiateContextualType(getContextualType(node, /*contextFlags*/ undefined), node, /*contextFlags*/ undefined)); + } + + function checkPropertyAssignment(node: PropertyAssignment, checkMode?: CheckMode): Type { + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + } + + return checkExpressionForMutableLocation(node.initializer, checkMode); + } + + function checkObjectLiteralMethod(node: MethodDeclaration, checkMode?: CheckMode): Type { + // Grammar checking + checkGrammarMethod(node); + + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + } + + const uninstantiatedType = checkFunctionExpressionOrObjectLiteralMethod(node, checkMode); + return instantiateTypeWithSingleGenericCallSignature(node, uninstantiatedType, checkMode); + } + + function instantiateTypeWithSingleGenericCallSignature(node: Expression | MethodDeclaration | QualifiedName, type: Type, checkMode?: CheckMode) { + if (checkMode && checkMode & (CheckMode.Inferential | CheckMode.SkipGenericFunctions)) { + const callSignature = getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ true); + const constructSignature = getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ true); + const signature = callSignature || constructSignature; + if (signature && signature.typeParameters) { + const contextualType = getApparentTypeOfContextualType(node as Expression, ContextFlags.NoConstraints); + if (contextualType) { + const contextualSignature = getSingleSignature(getNonNullableType(contextualType), callSignature ? SignatureKind.Call : SignatureKind.Construct, /*allowMembers*/ false); + if (contextualSignature && !contextualSignature.typeParameters) { + if (checkMode & CheckMode.SkipGenericFunctions) { + skippedGenericFunction(node, checkMode); + return anyFunctionType; + } + const context = getInferenceContext(node)!; + // We have an expression that is an argument of a generic function for which we are performing + // type argument inference. The expression is of a function type with a single generic call + // signature and a contextual function type with a single non-generic call signature. Now check + // if the outer function returns a function type with a single non-generic call signature and + // if some of the outer function type parameters have no inferences so far. If so, we can + // potentially add inferred type parameters to the outer function return type. + const returnType = context.signature && getReturnTypeOfSignature(context.signature); + const returnSignature = returnType && getSingleCallOrConstructSignature(returnType); + if (returnSignature && !returnSignature.typeParameters && !every(context.inferences, hasInferenceCandidates)) { + // Instantiate the signature with its own type parameters as type arguments, possibly + // renaming the type parameters to ensure they have unique names. + const uniqueTypeParameters = getUniqueTypeParameters(context, signature.typeParameters); + const instantiatedSignature = getSignatureInstantiationWithoutFillingInTypeArguments(signature, uniqueTypeParameters); + // Infer from the parameters of the instantiated signature to the parameters of the + // contextual signature starting with an empty set of inference candidates. + const inferences = map(context.inferences, info => createInferenceInfo(info.typeParameter)); + applyToParameterTypes(instantiatedSignature, contextualSignature, (source, target) => { + inferTypes(inferences, source, target, /*priority*/ 0, /*contravariant*/ true); + }); + if (some(inferences, hasInferenceCandidates)) { + // We have inference candidates, indicating that one or more type parameters are referenced + // in the parameter types of the contextual signature. Now also infer from the return type. + applyToReturnTypes(instantiatedSignature, contextualSignature, (source, target) => { + inferTypes(inferences, source, target); + }); + // If the type parameters for which we produced candidates do not have any inferences yet, + // we adopt the new inference candidates and add the type parameters of the expression type + // to the set of inferred type parameters for the outer function return type. + if (!hasOverlappingInferences(context.inferences, inferences)) { + mergeInferences(context.inferences, inferences); + context.inferredTypeParameters = concatenate(context.inferredTypeParameters, uniqueTypeParameters); + return getOrCreateTypeFromSignature(instantiatedSignature); + } + } + } + // TODO: The signature may reference any outer inference contexts, but we map pop off and then apply new inference contexts, and thus get different inferred types. + // That this is cached on the *first* such attempt is not currently an issue, since expression types *also* get cached on the first pass. If we ever properly speculate, though, + // the cached "isolatedSignatureType" signature field absolutely needs to be included in the list of speculative caches. + return getOrCreateTypeFromSignature(instantiateSignatureInContextOf(signature, contextualSignature, context), flatMap(inferenceContexts, c => c && map(c.inferences, i => i.typeParameter)).slice()); + } + } + } + } + return type; + } + + function skippedGenericFunction(node: Node, checkMode: CheckMode) { + if (checkMode & CheckMode.Inferential) { + // We have skipped a generic function during inferential typing. Obtain the inference context and + // indicate this has occurred such that we know a second pass of inference is be needed. + const context = getInferenceContext(node)!; + context.flags |= InferenceFlags.SkippedGenericFunction; + } + } + + function hasInferenceCandidates(info: InferenceInfo) { + return !!(info.candidates || info.contraCandidates); + } + + function hasInferenceCandidatesOrDefault(info: InferenceInfo) { + return !!(info.candidates || info.contraCandidates || hasTypeParameterDefault(info.typeParameter)); + } + + function hasOverlappingInferences(a: InferenceInfo[], b: InferenceInfo[]) { + for (let i = 0; i < a.length; i++) { + if (hasInferenceCandidates(a[i]) && hasInferenceCandidates(b[i])) { + return true; + } + } + return false; + } + + function mergeInferences(target: InferenceInfo[], source: InferenceInfo[]) { + for (let i = 0; i < target.length; i++) { + if (!hasInferenceCandidates(target[i]) && hasInferenceCandidates(source[i])) { + target[i] = source[i]; + } + } + } + + function getUniqueTypeParameters(context: InferenceContext, typeParameters: readonly TypeParameter[]): readonly TypeParameter[] { + const result: TypeParameter[] = []; + let oldTypeParameters: TypeParameter[] | undefined; + let newTypeParameters: TypeParameter[] | undefined; + for (const tp of typeParameters) { + const name = tp.symbol.escapedName; + if (hasTypeParameterByName(context.inferredTypeParameters, name) || hasTypeParameterByName(result, name)) { + const newName = getUniqueTypeParameterName(concatenate(context.inferredTypeParameters, result), name); + const symbol = createSymbol(SymbolFlags.TypeParameter, newName); + const newTypeParameter = createTypeParameter(symbol); + newTypeParameter.target = tp; + oldTypeParameters = append(oldTypeParameters, tp); + newTypeParameters = append(newTypeParameters, newTypeParameter); + result.push(newTypeParameter); + } + else { + result.push(tp); + } + } + if (newTypeParameters) { + const mapper = createTypeMapper(oldTypeParameters!, newTypeParameters); + for (const tp of newTypeParameters) { + tp.mapper = mapper; + } + } + return result; + } + + function hasTypeParameterByName(typeParameters: readonly TypeParameter[] | undefined, name: __String) { + return some(typeParameters, tp => tp.symbol.escapedName === name); + } + + function getUniqueTypeParameterName(typeParameters: readonly TypeParameter[], baseName: __String) { + let len = (baseName as string).length; + while (len > 1 && (baseName as string).charCodeAt(len - 1) >= CharacterCodes._0 && (baseName as string).charCodeAt(len - 1) <= CharacterCodes._9) len--; + const s = (baseName as string).slice(0, len); + for (let index = 1; true; index++) { + const augmentedName = s + index as __String; + if (!hasTypeParameterByName(typeParameters, augmentedName)) { + return augmentedName; + } + } + } + + function getReturnTypeOfSingleNonGenericCallSignature(funcType: Type) { + const signature = getSingleCallSignature(funcType); + if (signature && !signature.typeParameters) { + return getReturnTypeOfSignature(signature); + } + } + + function getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr: CallChain) { + const funcType = checkExpression(expr.expression); + const nonOptionalType = getOptionalExpressionType(funcType, expr.expression); + const returnType = getReturnTypeOfSingleNonGenericCallSignature(funcType); + return returnType && propagateOptionalTypeMarker(returnType, expr, nonOptionalType !== funcType); + } + + /** + * Returns the type of an expression. Unlike checkExpression, this function is simply concerned + * with computing the type and may not fully check all contained sub-expressions for errors. + */ + function getTypeOfExpression(node: Expression) { + // Don't bother caching types that require no flow analysis and are quick to compute. + const quickType = getQuickTypeOfExpression(node); + if (quickType) { + return quickType; + } + // If a type has been cached for the node, return it. + if (node.flags & NodeFlags.TypeCached && flowTypeCache) { + const cachedType = flowTypeCache[getNodeId(node)]; + if (cachedType) { + return cachedType; + } + } + const startInvocationCount = flowInvocationCount; + const type = checkExpression(node, CheckMode.TypeOnly); + // If control flow analysis was required to determine the type, it is worth caching. + if (flowInvocationCount !== startInvocationCount) { + const cache = flowTypeCache || (flowTypeCache = []); + cache[getNodeId(node)] = type; + setNodeFlags(node, node.flags | NodeFlags.TypeCached); + } + return type; + } + + function getQuickTypeOfExpression(node: Expression): Type | undefined { + let expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + if (isJSDocTypeAssertion(expr)) { + const type = getJSDocTypeAssertionType(expr); + if (!isConstTypeReference(type)) { + return getTypeFromTypeNode(type); + } + } + expr = skipParentheses(node); + if (isAwaitExpression(expr)) { + const type = getQuickTypeOfExpression(expr.expression); + return type ? getAwaitedType(type) : undefined; + } + // Optimize for the common case of a call to a function with a single non-generic call + // signature where we can just fetch the return type without checking the arguments. + if (isCallExpression(expr) && expr.expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(expr, /*requireStringLiteralLikeArgument*/ true) && !isSymbolOrSymbolForCall(expr)) { + return isCallChain(expr) ? getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr) : + getReturnTypeOfSingleNonGenericCallSignature(checkNonNullExpression(expr.expression)); + } + else if (isAssertionExpression(expr) && !isConstTypeReference(expr.type)) { + return getTypeFromTypeNode((expr as TypeAssertion).type); + } + else if (isLiteralExpression(node) || isBooleanLiteral(node)) { + return checkExpression(node); + } + return undefined; + } + + /** + * Returns the type of an expression. Unlike checkExpression, this function is simply concerned + * with computing the type and may not fully check all contained sub-expressions for errors. + * It is intended for uses where you know there is no contextual type, + * and requesting the contextual type might cause a circularity or other bad behaviour. + * It sets the contextual type of the node to any before calling getTypeOfExpression. + */ + function getContextFreeTypeOfExpression(node: Expression) { + const links = getNodeLinks(node); + if (links.contextFreeType) { + return links.contextFreeType; + } + pushContextualType(node, anyType, /*isCache*/ false); + const type = links.contextFreeType = checkExpression(node, CheckMode.SkipContextSensitive); + popContextualType(); + return type; + } + + function checkExpression(node: Expression | QualifiedName, checkMode?: CheckMode, forceTuple?: boolean): Type { + tracing?.push(tracing.Phase.Check, "checkExpression", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); + const saveCurrentNode = currentNode; + currentNode = node; + instantiationCount = 0; + const uninstantiatedType = checkExpressionWorker(node, checkMode, forceTuple); + const type = instantiateTypeWithSingleGenericCallSignature(node, uninstantiatedType, checkMode); + if (isConstEnumObjectType(type)) { + checkConstEnumAccess(node, type); + } + currentNode = saveCurrentNode; + tracing?.pop(); + return type; + } + + function checkConstEnumAccess(node: Expression | QualifiedName, type: Type) { + // enum object type for const enums are only permitted in: + // - 'left' in property access + // - 'object' in indexed access + // - target in rhs of import statement + const ok = (node.parent.kind === SyntaxKind.PropertyAccessExpression && (node.parent as PropertyAccessExpression).expression === node) || + (node.parent.kind === SyntaxKind.ElementAccessExpression && (node.parent as ElementAccessExpression).expression === node) || + ((node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.QualifiedName) && isInRightSideOfImportOrExportAssignment(node as Identifier) || + (node.parent.kind === SyntaxKind.TypeQuery && (node.parent as TypeQueryNode).exprName === node)) || + (node.parent.kind === SyntaxKind.ExportSpecifier); // We allow reexporting const enums + + if (!ok) { + error(node, Diagnostics.const_enums_can_only_be_used_in_property_or_index_access_expressions_or_the_right_hand_side_of_an_import_declaration_or_export_assignment_or_type_query); + } + + if (getIsolatedModules(compilerOptions)) { + Debug.assert(!!(type.symbol.flags & SymbolFlags.ConstEnum)); + const constEnumDeclaration = type.symbol.valueDeclaration as EnumDeclaration; + const redirect = host.getRedirectReferenceForResolutionFromSourceOfProject(getSourceFileOfNode(constEnumDeclaration).resolvedPath); + if (constEnumDeclaration.flags & NodeFlags.Ambient && !isValidTypeOnlyAliasUseSite(node) && (!redirect || !shouldPreserveConstEnums(redirect.commandLine.options))) { + error(node, Diagnostics.Cannot_access_ambient_const_enums_when_0_is_enabled, isolatedModulesLikeFlagName); + } + } + } + + function checkParenthesizedExpression(node: ParenthesizedExpression, checkMode?: CheckMode): Type { + if (hasJSDocNodes(node)) { + if (isJSDocSatisfiesExpression(node)) { + return checkSatisfiesExpressionWorker(node.expression, getJSDocSatisfiesExpressionType(node), checkMode); + } + if (isJSDocTypeAssertion(node)) { + return checkAssertionWorker(node, checkMode); + } + } + return checkExpression(node.expression, checkMode); + } + + function checkExpressionWorker(node: Expression | QualifiedName, checkMode: CheckMode | undefined, forceTuple?: boolean): Type { + const kind = node.kind; + if (cancellationToken) { + // Only bother checking on a few construct kinds. We don't want to be excessively + // hitting the cancellation token on every node we check. + switch (kind) { + case SyntaxKind.ClassExpression: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + cancellationToken.throwIfCancellationRequested(); + } + } + switch (kind) { + case SyntaxKind.Identifier: + return checkIdentifier(node as Identifier, checkMode); + case SyntaxKind.PrivateIdentifier: + return checkPrivateIdentifierExpression(node as PrivateIdentifier); + case SyntaxKind.ThisKeyword: + return checkThisExpression(node); + case SyntaxKind.SuperKeyword: + return checkSuperExpression(node); + case SyntaxKind.NullKeyword: + return nullWideningType; + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.StringLiteral: + return hasSkipDirectInferenceFlag(node) ? + blockedStringType : + getFreshTypeOfLiteralType(getStringLiteralType((node as StringLiteralLike).text)); + case SyntaxKind.NumericLiteral: + checkGrammarNumericLiteral(node as NumericLiteral); + return getFreshTypeOfLiteralType(getNumberLiteralType(+(node as NumericLiteral).text)); + case SyntaxKind.BigIntLiteral: + checkGrammarBigIntLiteral(node as BigIntLiteral); + return getFreshTypeOfLiteralType(getBigIntLiteralType({ + negative: false, + base10Value: parsePseudoBigInt((node as BigIntLiteral).text), + })); + case SyntaxKind.TrueKeyword: + return trueType; + case SyntaxKind.FalseKeyword: + return falseType; + case SyntaxKind.TemplateExpression: + return checkTemplateExpression(node as TemplateExpression); + case SyntaxKind.RegularExpressionLiteral: + return checkRegularExpressionLiteral(node as RegularExpressionLiteral); + case SyntaxKind.ArrayLiteralExpression: + return checkArrayLiteral(node as ArrayLiteralExpression, checkMode, forceTuple); + case SyntaxKind.ObjectLiteralExpression: + return checkObjectLiteral(node as ObjectLiteralExpression, checkMode); + case SyntaxKind.PropertyAccessExpression: + return checkPropertyAccessExpression(node as PropertyAccessExpression, checkMode); + case SyntaxKind.QualifiedName: + return checkQualifiedName(node as QualifiedName, checkMode); + case SyntaxKind.ElementAccessExpression: + return checkIndexedAccess(node as ElementAccessExpression, checkMode); + case SyntaxKind.CallExpression: + if ((node as CallExpression).expression.kind === SyntaxKind.ImportKeyword) { + return checkImportCallExpression(node as ImportCall); + } + // falls through + case SyntaxKind.NewExpression: + return checkCallExpression(node as CallExpression, checkMode); + case SyntaxKind.TaggedTemplateExpression: + return checkTaggedTemplateExpression(node as TaggedTemplateExpression); + case SyntaxKind.ParenthesizedExpression: + return checkParenthesizedExpression(node as ParenthesizedExpression, checkMode); + case SyntaxKind.ClassExpression: + return checkClassExpression(node as ClassExpression); + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + return checkFunctionExpressionOrObjectLiteralMethod(node as FunctionExpression | ArrowFunction, checkMode); + case SyntaxKind.TypeOfExpression: + return checkTypeOfExpression(node as TypeOfExpression); + case SyntaxKind.TypeAssertionExpression: + case SyntaxKind.AsExpression: + return checkAssertion(node as AssertionExpression, checkMode); + case SyntaxKind.NonNullExpression: + return checkNonNullAssertion(node as NonNullExpression); + case SyntaxKind.ExpressionWithTypeArguments: + return checkExpressionWithTypeArguments(node as ExpressionWithTypeArguments); + case SyntaxKind.SatisfiesExpression: + return checkSatisfiesExpression(node as SatisfiesExpression); + case SyntaxKind.MetaProperty: + return checkMetaProperty(node as MetaProperty); + case SyntaxKind.DeleteExpression: + return checkDeleteExpression(node as DeleteExpression); + case SyntaxKind.VoidExpression: + return checkVoidExpression(node as VoidExpression); + case SyntaxKind.AwaitExpression: + return checkAwaitExpression(node as AwaitExpression); + case SyntaxKind.PrefixUnaryExpression: + return checkPrefixUnaryExpression(node as PrefixUnaryExpression); + case SyntaxKind.PostfixUnaryExpression: + return checkPostfixUnaryExpression(node as PostfixUnaryExpression); + case SyntaxKind.BinaryExpression: + return checkBinaryExpression(node as BinaryExpression, checkMode); + case SyntaxKind.ConditionalExpression: + return checkConditionalExpression(node as ConditionalExpression, checkMode); + case SyntaxKind.SpreadElement: + return checkSpreadExpression(node as SpreadElement, checkMode); + case SyntaxKind.OmittedExpression: + return undefinedWideningType; + case SyntaxKind.YieldExpression: + return checkYieldExpression(node as YieldExpression); + case SyntaxKind.SyntheticExpression: + return checkSyntheticExpression(node as SyntheticExpression); + case SyntaxKind.JsxExpression: + return checkJsxExpression(node as JsxExpression, checkMode); + case SyntaxKind.JsxElement: + return checkJsxElement(node as JsxElement, checkMode); + case SyntaxKind.JsxSelfClosingElement: + return checkJsxSelfClosingElement(node as JsxSelfClosingElement, checkMode); + case SyntaxKind.JsxFragment: + return checkJsxFragment(node as JsxFragment); + case SyntaxKind.JsxAttributes: + return checkJsxAttributes(node as JsxAttributes, checkMode); + case SyntaxKind.JsxOpeningElement: + Debug.fail("Shouldn't ever directly check a JsxOpeningElement"); + } + return errorType; + } + + // DECLARATION AND STATEMENT TYPE CHECKING + + function checkTypeParameter(node: TypeParameterDeclaration) { + // Grammar Checking + checkGrammarModifiers(node); + if (node.expression) { + grammarErrorOnFirstToken(node.expression, Diagnostics.Type_expected); + } + + checkSourceElement(node.constraint); + checkSourceElement(node.default); + const typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node)); + // Resolve base constraint to reveal circularity errors + getBaseConstraintOfType(typeParameter); + if (!hasNonCircularTypeParameterDefault(typeParameter)) { + error(node.default, Diagnostics.Type_parameter_0_has_a_circular_default, typeToString(typeParameter)); + } + const constraintType = getConstraintOfTypeParameter(typeParameter); + const defaultType = getDefaultFromTypeParameter(typeParameter); + if (constraintType && defaultType) { + checkTypeAssignableTo(defaultType, getTypeWithThisArgument(instantiateType(constraintType, makeUnaryTypeMapper(typeParameter, defaultType)), defaultType), node.default, Diagnostics.Type_0_does_not_satisfy_the_constraint_1); + } + checkNodeDeferred(node); + addLazyDiagnostic(() => checkTypeNameIsReserved(node.name, Diagnostics.Type_parameter_name_cannot_be_0)); + } + + function checkTypeParameterDeferred(node: TypeParameterDeclaration) { + if (isInterfaceDeclaration(node.parent) || isClassLike(node.parent) || isTypeAliasDeclaration(node.parent)) { + const typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node)); + const modifiers = getTypeParameterModifiers(typeParameter) & (ModifierFlags.In | ModifierFlags.Out); + if (modifiers) { + const symbol = getSymbolOfDeclaration(node.parent); + if (isTypeAliasDeclaration(node.parent) && !(getObjectFlags(getDeclaredTypeOfSymbol(symbol)) & (ObjectFlags.Reference | ObjectFlags.Anonymous | ObjectFlags.Mapped))) { + error(node, Diagnostics.Variance_annotations_are_only_supported_in_type_aliases_for_object_function_constructor_and_mapped_types); + } + else if (modifiers === ModifierFlags.In || modifiers === ModifierFlags.Out) { + tracing?.push(tracing.Phase.CheckTypes, "checkTypeParameterDeferred", { parent: getTypeId(getDeclaredTypeOfSymbol(symbol)), id: getTypeId(typeParameter) }); + const source = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSubTypeForCheck : markerSuperTypeForCheck); + const target = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSuperTypeForCheck : markerSubTypeForCheck); + const saveVarianceTypeParameter = typeParameter; + varianceTypeParameter = typeParameter; + checkTypeAssignableTo(source, target, node, Diagnostics.Type_0_is_not_assignable_to_type_1_as_implied_by_variance_annotation); + varianceTypeParameter = saveVarianceTypeParameter; + tracing?.pop(); + } + } + } + } + + function checkParameter(node: ParameterDeclaration) { + // Grammar checking + // It is a SyntaxError if the Identifier "eval" or the Identifier "arguments" occurs as the + // Identifier in a PropertySetParameterList of a PropertyAssignment that is contained in strict code + // or if its FunctionBody is strict code(11.1.5). + checkGrammarModifiers(node); + + checkVariableLikeDeclaration(node); + const func = getContainingFunction(node)!; + if (hasSyntacticModifier(node, ModifierFlags.ParameterPropertyModifier)) { + if (!(func.kind === SyntaxKind.Constructor && nodeIsPresent(func.body))) { + error(node, Diagnostics.A_parameter_property_is_only_allowed_in_a_constructor_implementation); + } + if (func.kind === SyntaxKind.Constructor && isIdentifier(node.name) && node.name.escapedText === "constructor") { + error(node.name, Diagnostics.constructor_cannot_be_used_as_a_parameter_property_name); + } + } + if (!node.initializer && isOptionalDeclaration(node) && isBindingPattern(node.name) && (func as FunctionLikeDeclaration).body) { + error(node, Diagnostics.A_binding_pattern_parameter_cannot_be_optional_in_an_implementation_signature); + } + if (node.name && isIdentifier(node.name) && (node.name.escapedText === "this" || node.name.escapedText === "new")) { + if (func.parameters.indexOf(node) !== 0) { + error(node, Diagnostics.A_0_parameter_must_be_the_first_parameter, node.name.escapedText as string); + } + if (func.kind === SyntaxKind.Constructor || func.kind === SyntaxKind.ConstructSignature || func.kind === SyntaxKind.ConstructorType) { + error(node, Diagnostics.A_constructor_cannot_have_a_this_parameter); + } + if (func.kind === SyntaxKind.ArrowFunction) { + error(node, Diagnostics.An_arrow_function_cannot_have_a_this_parameter); + } + if (func.kind === SyntaxKind.GetAccessor || func.kind === SyntaxKind.SetAccessor) { + error(node, Diagnostics.get_and_set_accessors_cannot_declare_this_parameters); + } + } + + // Only check rest parameter type if it's not a binding pattern. Since binding patterns are + // not allowed in a rest parameter, we already have an error from checkGrammarParameterList. + if (node.dotDotDotToken && !isBindingPattern(node.name) && !isTypeAssignableTo(getReducedType(getTypeOfSymbol(node.symbol)), anyReadonlyArrayType)) { + error(node, Diagnostics.A_rest_parameter_must_be_of_an_array_type); + } + } + + function checkTypePredicate(node: TypePredicateNode): void { + const parent = getTypePredicateParent(node); + if (!parent) { + // The parent must not be valid. + error(node, Diagnostics.A_type_predicate_is_only_allowed_in_return_type_position_for_functions_and_methods); + return; + } + + const signature = getSignatureFromDeclaration(parent); + const typePredicate = getTypePredicateOfSignature(signature); + if (!typePredicate) { + return; + } + + checkSourceElement(node.type); + + const { parameterName } = node; + if (typePredicate.kind === TypePredicateKind.This || typePredicate.kind === TypePredicateKind.AssertsThis) { + getTypeFromThisTypeNode(parameterName as ThisTypeNode); + } + else { + if (typePredicate.parameterIndex >= 0) { + if (signatureHasRestParameter(signature) && typePredicate.parameterIndex === signature.parameters.length - 1) { + error(parameterName, Diagnostics.A_type_predicate_cannot_reference_a_rest_parameter); + } + else { + if (typePredicate.type) { + const leadingError = () => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.A_type_predicate_s_type_must_be_assignable_to_its_parameter_s_type); + checkTypeAssignableTo(typePredicate.type, getTypeOfSymbol(signature.parameters[typePredicate.parameterIndex]), node.type, /*headMessage*/ undefined, leadingError); + } + } + } + else if (parameterName) { + let hasReportedError = false; + for (const { name } of parent.parameters) { + if ( + isBindingPattern(name) && + checkIfTypePredicateVariableIsDeclaredInBindingPattern(name, parameterName, typePredicate.parameterName) + ) { + hasReportedError = true; + break; + } + } + if (!hasReportedError) { + error(node.parameterName, Diagnostics.Cannot_find_parameter_0, typePredicate.parameterName); + } + } + } + } + + function getTypePredicateParent(node: Node): SignatureDeclaration | undefined { + switch (node.parent.kind) { + case SyntaxKind.ArrowFunction: + case SyntaxKind.CallSignature: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.FunctionType: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + const parent = node.parent as SignatureDeclaration; + if (node === parent.type) { + return parent; + } + } + } + + function checkIfTypePredicateVariableIsDeclaredInBindingPattern( + pattern: BindingPattern, + predicateVariableNode: Node, + predicateVariableName: string, + ) { + for (const element of pattern.elements) { + if (isOmittedExpression(element)) { + continue; + } + + const name = element.name; + if (name.kind === SyntaxKind.Identifier && name.escapedText === predicateVariableName) { + error(predicateVariableNode, Diagnostics.A_type_predicate_cannot_reference_element_0_in_a_binding_pattern, predicateVariableName); + return true; + } + else if (name.kind === SyntaxKind.ArrayBindingPattern || name.kind === SyntaxKind.ObjectBindingPattern) { + if ( + checkIfTypePredicateVariableIsDeclaredInBindingPattern( + name, + predicateVariableNode, + predicateVariableName, + ) + ) { + return true; + } + } + } + } + + function checkSignatureDeclaration(node: SignatureDeclaration) { + // Grammar checking + if (node.kind === SyntaxKind.IndexSignature) { + checkGrammarIndexSignature(node); + } + // TODO (yuisu): Remove this check in else-if when SyntaxKind.Construct is moved and ambient context is handled + else if ( + node.kind === SyntaxKind.FunctionType || node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.ConstructorType || + node.kind === SyntaxKind.CallSignature || node.kind === SyntaxKind.Constructor || + node.kind === SyntaxKind.ConstructSignature + ) { + checkGrammarFunctionLikeDeclaration(node as FunctionLikeDeclaration); + } + + const functionFlags = getFunctionFlags(node as FunctionLikeDeclaration); + if (!(functionFlags & FunctionFlags.Invalid)) { + // Async generators prior to ES2018 require the __await and __asyncGenerator helpers + if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.AsyncGenerator && languageVersion < LanguageFeatureMinimumTarget.AsyncGenerators) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.AsyncGeneratorIncludes); + } + + // Async functions prior to ES2017 require the __awaiter helper + if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async && languageVersion < LanguageFeatureMinimumTarget.AsyncFunctions) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Awaiter); + } + + // Generator functions, Async functions, and Async Generator functions prior to + // ES2015 require the __generator helper + if ((functionFlags & FunctionFlags.AsyncGenerator) !== FunctionFlags.Normal && languageVersion < LanguageFeatureMinimumTarget.Generators) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Generator); + } + } + + checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); + checkUnmatchedJSDocParameters(node); + + forEach(node.parameters, checkParameter); + + // TODO(rbuckton): Should we start checking JSDoc types? + if (node.type) { + checkSourceElement(node.type); + } + + addLazyDiagnostic(checkSignatureDeclarationDiagnostics); + + function checkSignatureDeclarationDiagnostics() { + checkCollisionWithArgumentsInGeneratedCode(node); + + let returnTypeNode = getEffectiveReturnTypeNode(node); + let returnTypeErrorLocation = returnTypeNode; + + if (isInJSFile(node)) { + const typeTag = getJSDocTypeTag(node); + if (typeTag && typeTag.typeExpression && isTypeReferenceNode(typeTag.typeExpression.type)) { + const signature = getSingleCallSignature(getTypeFromTypeNode(typeTag.typeExpression)); + if (signature && signature.declaration) { + returnTypeNode = getEffectiveReturnTypeNode(signature.declaration); + returnTypeErrorLocation = typeTag.typeExpression.type; + } + } + } + + if (noImplicitAny && !returnTypeNode) { + switch (node.kind) { + case SyntaxKind.ConstructSignature: + error(node, Diagnostics.Construct_signature_which_lacks_return_type_annotation_implicitly_has_an_any_return_type); + break; + case SyntaxKind.CallSignature: + error(node, Diagnostics.Call_signature_which_lacks_return_type_annotation_implicitly_has_an_any_return_type); + break; + } + } + + if (returnTypeNode && returnTypeErrorLocation) { + const functionFlags = getFunctionFlags(node as FunctionDeclaration); + if ((functionFlags & (FunctionFlags.Invalid | FunctionFlags.Generator)) === FunctionFlags.Generator) { + const returnType = getTypeFromTypeNode(returnTypeNode); + if (returnType === voidType) { + error(returnTypeErrorLocation, Diagnostics.A_generator_cannot_have_a_void_type_annotation); + } + else { + checkGeneratorInstantiationAssignabilityToReturnType(returnType, functionFlags, returnTypeErrorLocation); + } + } + else if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async) { + checkAsyncFunctionReturnType(node as FunctionLikeDeclaration, returnTypeNode, returnTypeErrorLocation); + } + } + if (node.kind !== SyntaxKind.IndexSignature && node.kind !== SyntaxKind.JSDocFunctionType) { + registerForUnusedIdentifiersCheck(node); + } + } + } + + function checkGeneratorInstantiationAssignabilityToReturnType(returnType: Type, functionFlags: FunctionFlags, errorNode?: TypeNode) { + // Naively, one could check that Generator is assignable to the return type annotation. + // However, that would not catch the error in the following case. + // + // interface BadGenerator extends Iterable, Iterator { } + // function* g(): BadGenerator { } // Iterable and Iterator have different types! + // + const generatorYieldType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Yield, returnType, (functionFlags & FunctionFlags.Async) !== 0) || anyType; + const generatorReturnType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, returnType, (functionFlags & FunctionFlags.Async) !== 0) || generatorYieldType; + const generatorNextType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Next, returnType, (functionFlags & FunctionFlags.Async) !== 0) || unknownType; + const generatorInstantiation = createGeneratorType(generatorYieldType, generatorReturnType, generatorNextType, !!(functionFlags & FunctionFlags.Async)); + + return checkTypeAssignableTo(generatorInstantiation, returnType, errorNode); + } + + function checkClassForDuplicateDeclarations(node: ClassLikeDeclaration) { + const instanceNames = new Map<__String, DeclarationMeaning>(); + const staticNames = new Map<__String, DeclarationMeaning>(); + // instance and static private identifiers share the same scope + const privateIdentifiers = new Map<__String, DeclarationMeaning>(); + for (const member of node.members) { + if (member.kind === SyntaxKind.Constructor) { + for (const param of (member as ConstructorDeclaration).parameters) { + if (isParameterPropertyDeclaration(param, member) && !isBindingPattern(param.name)) { + addName(instanceNames, param.name, param.name.escapedText, DeclarationMeaning.GetOrSetAccessor); + } + } + } + else { + const isStaticMember = isStatic(member); + const name = member.name; + if (!name) { + continue; + } + const isPrivate = isPrivateIdentifier(name); + const privateStaticFlags = isPrivate && isStaticMember ? DeclarationMeaning.PrivateStatic : 0; + const names = isPrivate ? privateIdentifiers : + isStaticMember ? staticNames : + instanceNames; + + const memberName = name && getEffectivePropertyNameForPropertyNameNode(name); + if (memberName) { + switch (member.kind) { + case SyntaxKind.GetAccessor: + addName(names, name, memberName, DeclarationMeaning.GetAccessor | privateStaticFlags); + break; + + case SyntaxKind.SetAccessor: + addName(names, name, memberName, DeclarationMeaning.SetAccessor | privateStaticFlags); + break; + + case SyntaxKind.PropertyDeclaration: + addName(names, name, memberName, DeclarationMeaning.GetOrSetAccessor | privateStaticFlags); + break; + + case SyntaxKind.MethodDeclaration: + addName(names, name, memberName, DeclarationMeaning.Method | privateStaticFlags); + break; + } + } + } + } + + function addName(names: Map<__String, DeclarationMeaning>, location: Node, name: __String, meaning: DeclarationMeaning) { + const prev = names.get(name); + if (prev) { + // For private identifiers, do not allow mixing of static and instance members with the same name + if ((prev & DeclarationMeaning.PrivateStatic) !== (meaning & DeclarationMeaning.PrivateStatic)) { + error(location, Diagnostics.Duplicate_identifier_0_Static_and_instance_elements_cannot_share_the_same_private_name, getTextOfNode(location)); + } + else { + const prevIsMethod = !!(prev & DeclarationMeaning.Method); + const isMethod = !!(meaning & DeclarationMeaning.Method); + if (prevIsMethod || isMethod) { + if (prevIsMethod !== isMethod) { + error(location, Diagnostics.Duplicate_identifier_0, getTextOfNode(location)); + } + // If this is a method/method duplication is might be an overload, so this will be handled when overloads are considered + } + else if (prev & meaning & ~DeclarationMeaning.PrivateStatic) { + error(location, Diagnostics.Duplicate_identifier_0, getTextOfNode(location)); + } + else { + names.set(name, prev | meaning); + } + } + } + else { + names.set(name, meaning); + } + } + } + + /** + * Static members being set on a constructor function may conflict with built-in properties + * of Function. Esp. in ECMAScript 5 there are non-configurable and non-writable + * built-in properties. This check issues a transpile error when a class has a static + * member with the same name as a non-writable built-in property. + * + * @see http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.3 + * @see http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.5 + * @see http://www.ecma-international.org/ecma-262/6.0/#sec-properties-of-the-function-constructor + * @see http://www.ecma-international.org/ecma-262/6.0/#sec-function-instances + */ + function checkClassForStaticPropertyNameConflicts(node: ClassLikeDeclaration) { + for (const member of node.members) { + const memberNameNode = member.name; + const isStaticMember = isStatic(member); + if (isStaticMember && memberNameNode) { + const memberName = getEffectivePropertyNameForPropertyNameNode(memberNameNode); + switch (memberName) { + case "name": + case "length": + case "caller": + case "arguments": + if (useDefineForClassFields) { + break; + } + // fall through + case "prototype": + const message = Diagnostics.Static_property_0_conflicts_with_built_in_property_Function_0_of_constructor_function_1; + const className = getNameOfSymbolAsWritten(getSymbolOfDeclaration(node)); + error(memberNameNode, message, memberName, className); + break; + } + } + } + } + + function checkObjectTypeForDuplicateDeclarations(node: TypeLiteralNode | InterfaceDeclaration) { + const names = new Map(); + for (const member of node.members) { + if (member.kind === SyntaxKind.PropertySignature) { + let memberName: string; + const name = member.name!; + switch (name.kind) { + case SyntaxKind.StringLiteral: + case SyntaxKind.NumericLiteral: + memberName = name.text; + break; + case SyntaxKind.Identifier: + memberName = idText(name); + break; + default: + continue; + } + + if (names.get(memberName)) { + error(getNameOfDeclaration(member.symbol.valueDeclaration), Diagnostics.Duplicate_identifier_0, memberName); + error(member.name, Diagnostics.Duplicate_identifier_0, memberName); + } + else { + names.set(memberName, true); + } + } + } + } + + function checkTypeForDuplicateIndexSignatures(node: ClassLikeDeclaration | InterfaceDeclaration | TypeLiteralNode) { + if (node.kind === SyntaxKind.InterfaceDeclaration) { + const nodeSymbol = getSymbolOfDeclaration(node); + // in case of merging interface declaration it is possible that we'll enter this check procedure several times for every declaration + // to prevent this run check only for the first declaration of a given kind + if (nodeSymbol.declarations && nodeSymbol.declarations.length > 0 && nodeSymbol.declarations[0] !== node) { + return; + } + } + + // TypeScript 1.0 spec (April 2014) + // 3.7.4: An object type can contain at most one string index signature and one numeric index signature. + // 8.5: A class declaration can have at most one string index member declaration and one numeric index member declaration + const indexSymbol = getIndexSymbol(getSymbolOfDeclaration(node)); + if (indexSymbol?.declarations) { + const indexSignatureMap = new Map(); + for (const declaration of (indexSymbol.declarations as IndexSignatureDeclaration[])) { + if (declaration.parameters.length === 1 && declaration.parameters[0].type) { + forEachType(getTypeFromTypeNode(declaration.parameters[0].type), type => { + const entry = indexSignatureMap.get(getTypeId(type)); + if (entry) { + entry.declarations.push(declaration); + } + else { + indexSignatureMap.set(getTypeId(type), { type, declarations: [declaration] }); + } + }); + } + } + indexSignatureMap.forEach(entry => { + if (entry.declarations.length > 1) { + for (const declaration of entry.declarations) { + error(declaration, Diagnostics.Duplicate_index_signature_for_type_0, typeToString(entry.type)); + } + } + }); + } + } + + function checkPropertyDeclaration(node: PropertyDeclaration | PropertySignature) { + // Grammar checking + if (!checkGrammarModifiers(node) && !checkGrammarProperty(node)) checkGrammarComputedPropertyName(node.name); + checkVariableLikeDeclaration(node); + + setNodeLinksForPrivateIdentifierScope(node); + + // property signatures already report "initializer not allowed in ambient context" elsewhere + if (hasSyntacticModifier(node, ModifierFlags.Abstract) && node.kind === SyntaxKind.PropertyDeclaration && node.initializer) { + error(node, Diagnostics.Property_0_cannot_have_an_initializer_because_it_is_marked_abstract, declarationNameToString(node.name)); + } + } + + function checkPropertySignature(node: PropertySignature) { + if (isPrivateIdentifier(node.name)) { + error(node, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + return checkPropertyDeclaration(node); + } + + function checkMethodDeclaration(node: MethodDeclaration | MethodSignature) { + // Grammar checking + if (!checkGrammarMethod(node)) checkGrammarComputedPropertyName(node.name); + + if (isMethodDeclaration(node) && node.asteriskToken && isIdentifier(node.name) && idText(node.name) === "constructor") { + error(node.name, Diagnostics.Class_constructor_may_not_be_a_generator); + } + + // Grammar checking for modifiers is done inside the function checkGrammarFunctionLikeDeclaration + checkFunctionOrMethodDeclaration(node); + + // method signatures already report "implementation not allowed in ambient context" elsewhere + if (hasSyntacticModifier(node, ModifierFlags.Abstract) && node.kind === SyntaxKind.MethodDeclaration && node.body) { + error(node, Diagnostics.Method_0_cannot_have_an_implementation_because_it_is_marked_abstract, declarationNameToString(node.name)); + } + + // Private named methods are only allowed in class declarations + if (isPrivateIdentifier(node.name) && !getContainingClass(node)) { + error(node, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + + setNodeLinksForPrivateIdentifierScope(node); + } + + function setNodeLinksForPrivateIdentifierScope(node: PropertyDeclaration | PropertySignature | MethodDeclaration | MethodSignature | AccessorDeclaration) { + if (isPrivateIdentifier(node.name)) { + if ( + languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators || + !useDefineForClassFields + ) { + for (let lexicalScope = getEnclosingBlockScopeContainer(node); !!lexicalScope; lexicalScope = getEnclosingBlockScopeContainer(lexicalScope)) { + getNodeLinks(lexicalScope).flags |= NodeCheckFlags.ContainsClassWithPrivateIdentifiers; + } + + // If this is a private element in a class expression inside the body of a loop, + // then we must use a block-scoped binding to store the additional variables required + // to transform private elements. + if (isClassExpression(node.parent)) { + const enclosingIterationStatement = getEnclosingIterationStatement(node.parent); + if (enclosingIterationStatement) { + getNodeLinks(node.name).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; + } + } + } + } + } + + function checkClassStaticBlockDeclaration(node: ClassStaticBlockDeclaration) { + checkGrammarModifiers(node); + + forEachChild(node, checkSourceElement); + } + + function checkConstructorDeclaration(node: ConstructorDeclaration) { + // Grammar check on signature of constructor and modifier of the constructor is done in checkSignatureDeclaration function. + checkSignatureDeclaration(node); + // Grammar check for checking only related to constructorDeclaration + if (!checkGrammarConstructorTypeParameters(node)) checkGrammarConstructorTypeAnnotation(node); + + checkSourceElement(node.body); + + const symbol = getSymbolOfDeclaration(node); + const firstDeclaration = getDeclarationOfKind(symbol, node.kind); + + // Only type check the symbol once + if (node === firstDeclaration) { + checkFunctionOrConstructorSymbol(symbol); + } + + // exit early in the case of signature - super checks are not relevant to them + if (nodeIsMissing(node.body)) { + return; + } + + addLazyDiagnostic(checkConstructorDeclarationDiagnostics); + + return; + + function isInstancePropertyWithInitializerOrPrivateIdentifierProperty(n: Node): boolean { + if (isPrivateIdentifierClassElementDeclaration(n)) { + return true; + } + return n.kind === SyntaxKind.PropertyDeclaration && + !isStatic(n) && + !!(n as PropertyDeclaration).initializer; + } + + function checkConstructorDeclarationDiagnostics() { + // TS 1.0 spec (April 2014): 8.3.2 + // Constructors of classes with no extends clause may not contain super calls, whereas + // constructors of derived classes must contain at least one super call somewhere in their function body. + const containingClassDecl = node.parent; + if (getClassExtendsHeritageElement(containingClassDecl)) { + captureLexicalThis(node.parent, containingClassDecl); + const classExtendsNull = classDeclarationExtendsNull(containingClassDecl); + const superCall = findFirstSuperCall(node.body!); + if (superCall) { + if (classExtendsNull) { + error(superCall, Diagnostics.A_constructor_cannot_contain_a_super_call_when_its_class_extends_null); + } + + // A super call must be root-level in a constructor if both of the following are true: + // - The containing class is a derived class. + // - The constructor declares parameter properties + // or the containing class declares instance member variables with initializers. + + const superCallShouldBeRootLevel = !emitStandardClassFields && + (some(node.parent.members, isInstancePropertyWithInitializerOrPrivateIdentifierProperty) || + some(node.parameters, p => hasSyntacticModifier(p, ModifierFlags.ParameterPropertyModifier))); + + if (superCallShouldBeRootLevel) { + // Until we have better flow analysis, it is an error to place the super call within any kind of block or conditional + // See GH #8277 + if (!superCallIsRootLevelInConstructor(superCall, node.body!)) { + error(superCall, Diagnostics.A_super_call_must_be_a_root_level_statement_within_a_constructor_of_a_derived_class_that_contains_initialized_properties_parameter_properties_or_private_identifiers); + } + // Skip past any prologue directives to check statements for referring to 'super' or 'this' before a super call + else { + let superCallStatement: ExpressionStatement | undefined; + + for (const statement of node.body!.statements) { + if (isExpressionStatement(statement) && isSuperCall(skipOuterExpressions(statement.expression))) { + superCallStatement = statement; + break; + } + if (nodeImmediatelyReferencesSuperOrThis(statement)) { + break; + } + } + + // Until we have better flow analysis, it is an error to place the super call within any kind of block or conditional + // See GH #8277 + if (superCallStatement === undefined) { + error(node, Diagnostics.A_super_call_must_be_the_first_statement_in_the_constructor_to_refer_to_super_or_this_when_a_derived_class_contains_initialized_properties_parameter_properties_or_private_identifiers); + } + } + } + } + else if (!classExtendsNull) { + error(node, Diagnostics.Constructors_for_derived_classes_must_contain_a_super_call); + } + } + } + } + + function superCallIsRootLevelInConstructor(superCall: Node, body: Block) { + const superCallParent = walkUpParenthesizedExpressions(superCall.parent); + return isExpressionStatement(superCallParent) && superCallParent.parent === body; + } + + function nodeImmediatelyReferencesSuperOrThis(node: Node): boolean { + if (node.kind === SyntaxKind.SuperKeyword || node.kind === SyntaxKind.ThisKeyword) { + return true; + } + + if (isThisContainerOrFunctionBlock(node)) { + return false; + } + + return !!forEachChild(node, nodeImmediatelyReferencesSuperOrThis); + } + + function checkAccessorDeclaration(node: AccessorDeclaration) { + if (isIdentifier(node.name) && idText(node.name) === "constructor" && isClassLike(node.parent)) { + error(node.name, Diagnostics.Class_constructor_may_not_be_an_accessor); + } + addLazyDiagnostic(checkAccessorDeclarationDiagnostics); + checkSourceElement(node.body); + setNodeLinksForPrivateIdentifierScope(node); + + function checkAccessorDeclarationDiagnostics() { + // Grammar checking accessors + if (!checkGrammarFunctionLikeDeclaration(node) && !checkGrammarAccessor(node)) checkGrammarComputedPropertyName(node.name); + + checkDecorators(node); + checkSignatureDeclaration(node); + if (node.kind === SyntaxKind.GetAccessor) { + if (!(node.flags & NodeFlags.Ambient) && nodeIsPresent(node.body) && (node.flags & NodeFlags.HasImplicitReturn)) { + if (!(node.flags & NodeFlags.HasExplicitReturn)) { + error(node.name, Diagnostics.A_get_accessor_must_return_a_value); + } + } + } + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + } + + if (hasBindableName(node)) { + // TypeScript 1.0 spec (April 2014): 8.4.3 + // Accessors for the same member name must specify the same accessibility. + const symbol = getSymbolOfDeclaration(node); + const getter = getDeclarationOfKind(symbol, SyntaxKind.GetAccessor); + const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor); + if (getter && setter && !(getNodeCheckFlags(getter) & NodeCheckFlags.TypeChecked)) { + getNodeLinks(getter).flags |= NodeCheckFlags.TypeChecked; + const getterFlags = getEffectiveModifierFlags(getter); + const setterFlags = getEffectiveModifierFlags(setter); + if ((getterFlags & ModifierFlags.Abstract) !== (setterFlags & ModifierFlags.Abstract)) { + error(getter.name, Diagnostics.Accessors_must_both_be_abstract_or_non_abstract); + error(setter.name, Diagnostics.Accessors_must_both_be_abstract_or_non_abstract); + } + if ( + ((getterFlags & ModifierFlags.Protected) && !(setterFlags & (ModifierFlags.Protected | ModifierFlags.Private))) || + ((getterFlags & ModifierFlags.Private) && !(setterFlags & ModifierFlags.Private)) + ) { + error(getter.name, Diagnostics.A_get_accessor_must_be_at_least_as_accessible_as_the_setter); + error(setter.name, Diagnostics.A_get_accessor_must_be_at_least_as_accessible_as_the_setter); + } + } + } + const returnType = getTypeOfAccessors(getSymbolOfDeclaration(node)); + if (node.kind === SyntaxKind.GetAccessor) { + checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType); + } + } + } + + function checkMissingDeclaration(node: Node) { + checkDecorators(node); + } + + function getEffectiveTypeArgumentAtIndex(node: TypeReferenceNode | ExpressionWithTypeArguments, typeParameters: readonly TypeParameter[], index: number): Type { + if (node.typeArguments && index < node.typeArguments.length) { + return getTypeFromTypeNode(node.typeArguments[index]); + } + return getEffectiveTypeArguments(node, typeParameters)[index]; + } + + function getEffectiveTypeArguments(node: TypeReferenceNode | ExpressionWithTypeArguments | NodeWithTypeArguments, typeParameters: readonly TypeParameter[]): Type[] { + return fillMissingTypeArguments(map(node.typeArguments!, getTypeFromTypeNode), typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(node)); + } + + function checkTypeArgumentConstraints(node: TypeReferenceNode | ExpressionWithTypeArguments | NodeWithTypeArguments, typeParameters: readonly TypeParameter[]): boolean { + let typeArguments: Type[] | undefined; + let mapper: TypeMapper | undefined; + let result = true; + for (let i = 0; i < typeParameters.length; i++) { + const constraint = getConstraintOfTypeParameter(typeParameters[i]); + if (constraint) { + if (!typeArguments) { + typeArguments = getEffectiveTypeArguments(node, typeParameters); + mapper = createTypeMapper(typeParameters, typeArguments); + } + result = result && checkTypeAssignableTo( + typeArguments[i], + instantiateType(constraint, mapper), + node.typeArguments![i], + Diagnostics.Type_0_does_not_satisfy_the_constraint_1, + ); + } + } + return result; + } + + function getTypeParametersForTypeAndSymbol(type: Type, symbol: Symbol) { + if (!isErrorType(type)) { + return symbol.flags & SymbolFlags.TypeAlias && getSymbolLinks(symbol).typeParameters || + (getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).target.localTypeParameters : undefined); + } + return undefined; + } + + function getTypeParametersForTypeReferenceOrImport(node: TypeReferenceNode | ExpressionWithTypeArguments | ImportTypeNode) { + const type = getTypeFromTypeNode(node); + if (!isErrorType(type)) { + const symbol = getNodeLinks(node).resolvedSymbol; + if (symbol) { + return getTypeParametersForTypeAndSymbol(type, symbol); + } + } + return undefined; + } + + function checkTypeReferenceNode(node: TypeReferenceNode | ExpressionWithTypeArguments) { + checkGrammarTypeArguments(node, node.typeArguments); + if (node.kind === SyntaxKind.TypeReference && !isInJSFile(node) && !isInJSDoc(node) && node.typeArguments && node.typeName.end !== node.typeArguments.pos) { + // If there was a token between the type name and the type arguments, check if it was a DotToken + const sourceFile = getSourceFileOfNode(node); + if (scanTokenAtPosition(sourceFile, node.typeName.end) === SyntaxKind.DotToken) { + grammarErrorAtPos(node, skipTrivia(sourceFile.text, node.typeName.end), 1, Diagnostics.JSDoc_types_can_only_be_used_inside_documentation_comments); + } + } + forEach(node.typeArguments, checkSourceElement); + checkTypeReferenceOrImport(node); + } + + function checkTypeReferenceOrImport(node: TypeReferenceNode | ExpressionWithTypeArguments | ImportTypeNode) { + const type = getTypeFromTypeNode(node); + if (!isErrorType(type)) { + if (node.typeArguments) { + addLazyDiagnostic(() => { + const typeParameters = getTypeParametersForTypeReferenceOrImport(node); + if (typeParameters) { + checkTypeArgumentConstraints(node, typeParameters); + } + }); + } + const symbol = getNodeLinks(node).resolvedSymbol; + if (symbol) { + if (some(symbol.declarations, d => isTypeDeclaration(d) && !!(d.flags & NodeFlags.Deprecated))) { + addDeprecatedSuggestion( + getDeprecatedSuggestionNode(node), + symbol.declarations!, + symbol.escapedName as string, + ); + } + } + } + } + + function getTypeArgumentConstraint(node: TypeNode): Type | undefined { + const typeReferenceNode = tryCast(node.parent, isTypeReferenceType); + if (!typeReferenceNode) return undefined; + const typeParameters = getTypeParametersForTypeReferenceOrImport(typeReferenceNode); + if (!typeParameters) return undefined; + const constraint = getConstraintOfTypeParameter(typeParameters[typeReferenceNode.typeArguments!.indexOf(node)]); + return constraint && instantiateType(constraint, createTypeMapper(typeParameters, getEffectiveTypeArguments(typeReferenceNode, typeParameters))); + } + + function checkTypeQuery(node: TypeQueryNode) { + getTypeFromTypeQueryNode(node); + } + + function checkTypeLiteral(node: TypeLiteralNode) { + forEach(node.members, checkSourceElement); + addLazyDiagnostic(checkTypeLiteralDiagnostics); + + function checkTypeLiteralDiagnostics() { + const type = getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node); + checkIndexConstraints(type, type.symbol); + checkTypeForDuplicateIndexSignatures(node); + checkObjectTypeForDuplicateDeclarations(node); + } + } + + function checkArrayType(node: ArrayTypeNode) { + checkSourceElement(node.elementType); + } + + function checkTupleType(node: TupleTypeNode) { + let seenOptionalElement = false; + let seenRestElement = false; + for (const e of node.elements) { + let flags = getTupleElementFlags(e); + if (flags & ElementFlags.Variadic) { + const type = getTypeFromTypeNode((e as RestTypeNode | NamedTupleMember).type); + if (!isArrayLikeType(type)) { + error(e, Diagnostics.A_rest_element_type_must_be_an_array_type); + break; + } + if (isArrayType(type) || isTupleType(type) && type.target.combinedFlags & ElementFlags.Rest) { + flags |= ElementFlags.Rest; + } + } + if (flags & ElementFlags.Rest) { + if (seenRestElement) { + grammarErrorOnNode(e, Diagnostics.A_rest_element_cannot_follow_another_rest_element); + break; + } + seenRestElement = true; + } + else if (flags & ElementFlags.Optional) { + if (seenRestElement) { + grammarErrorOnNode(e, Diagnostics.An_optional_element_cannot_follow_a_rest_element); + break; + } + seenOptionalElement = true; + } + else if (flags & ElementFlags.Required && seenOptionalElement) { + grammarErrorOnNode(e, Diagnostics.A_required_element_cannot_follow_an_optional_element); + break; + } + } + forEach(node.elements, checkSourceElement); + getTypeFromTypeNode(node); + } + + function checkUnionOrIntersectionType(node: UnionOrIntersectionTypeNode) { + forEach(node.types, checkSourceElement); + getTypeFromTypeNode(node); + } + + function checkIndexedAccessIndexType(type: Type, accessNode: IndexedAccessTypeNode | ElementAccessExpression) { + if (!(type.flags & TypeFlags.IndexedAccess)) { + return type; + } + // Check if the index type is assignable to 'keyof T' for the object type. + const objectType = (type as IndexedAccessType).objectType; + const indexType = (type as IndexedAccessType).indexType; + // skip index type deferral on remapping mapped types + const objectIndexType = isGenericMappedType(objectType) && getMappedTypeNameTypeKind(objectType) === MappedTypeNameTypeKind.Remapping + ? getIndexTypeForMappedType(objectType, IndexFlags.None) + : getIndexType(objectType, IndexFlags.None); + const hasNumberIndexInfo = !!getIndexInfoOfType(objectType, numberType); + if (everyType(indexType, t => isTypeAssignableTo(t, objectIndexType) || hasNumberIndexInfo && isApplicableIndexType(t, numberType))) { + if ( + accessNode.kind === SyntaxKind.ElementAccessExpression && isAssignmentTarget(accessNode) && + getObjectFlags(objectType) & ObjectFlags.Mapped && getMappedTypeModifiers(objectType as MappedType) & MappedTypeModifiers.IncludeReadonly + ) { + error(accessNode, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType)); + } + return type; + } + if (isGenericObjectType(objectType)) { + const propertyName = getPropertyNameFromIndex(indexType, accessNode); + if (propertyName) { + const propertySymbol = forEachType(getApparentType(objectType), t => getPropertyOfType(t, propertyName)); + if (propertySymbol && getDeclarationModifierFlagsFromSymbol(propertySymbol) & ModifierFlags.NonPublicAccessibilityModifier) { + error(accessNode, Diagnostics.Private_or_protected_member_0_cannot_be_accessed_on_a_type_parameter, unescapeLeadingUnderscores(propertyName)); + return errorType; + } + } + } + error(accessNode, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(objectType)); + return errorType; + } + + function checkIndexedAccessType(node: IndexedAccessTypeNode) { + checkSourceElement(node.objectType); + checkSourceElement(node.indexType); + checkIndexedAccessIndexType(getTypeFromIndexedAccessTypeNode(node), node); + } + + function checkMappedType(node: MappedTypeNode) { + checkGrammarMappedType(node); + checkSourceElement(node.typeParameter); + checkSourceElement(node.nameType); + checkSourceElement(node.type); + + if (!node.type) { + reportImplicitAny(node, anyType); + } + + const type = getTypeFromMappedTypeNode(node) as MappedType; + const nameType = getNameTypeFromMappedType(type); + if (nameType) { + checkTypeAssignableTo(nameType, stringNumberSymbolType, node.nameType); + } + else { + const constraintType = getConstraintTypeFromMappedType(type); + checkTypeAssignableTo(constraintType, stringNumberSymbolType, getEffectiveConstraintOfTypeParameter(node.typeParameter)); + } + } + + function checkGrammarMappedType(node: MappedTypeNode) { + if (node.members?.length) { + return grammarErrorOnNode(node.members[0], Diagnostics.A_mapped_type_may_not_declare_properties_or_methods); + } + } + + function checkThisType(node: ThisTypeNode) { + getTypeFromThisTypeNode(node); + } + + function checkTypeOperator(node: TypeOperatorNode) { + checkGrammarTypeOperatorNode(node); + checkSourceElement(node.type); + } + + function checkConditionalType(node: ConditionalTypeNode) { + forEachChild(node, checkSourceElement); + } + + function checkInferType(node: InferTypeNode) { + if (!findAncestor(node, n => n.parent && n.parent.kind === SyntaxKind.ConditionalType && (n.parent as ConditionalTypeNode).extendsType === n)) { + grammarErrorOnNode(node, Diagnostics.infer_declarations_are_only_permitted_in_the_extends_clause_of_a_conditional_type); + } + checkSourceElement(node.typeParameter); + const symbol = getSymbolOfDeclaration(node.typeParameter); + if (symbol.declarations && symbol.declarations.length > 1) { + const links = getSymbolLinks(symbol); + if (!links.typeParametersChecked) { + links.typeParametersChecked = true; + const typeParameter = getDeclaredTypeOfTypeParameter(symbol); + const declarations: TypeParameterDeclaration[] = getDeclarationsOfKind(symbol, SyntaxKind.TypeParameter); + if (!areTypeParametersIdentical(declarations, [typeParameter], decl => [decl])) { + // Report an error on every conflicting declaration. + const name = symbolToString(symbol); + for (const declaration of declarations) { + error(declaration.name, Diagnostics.All_declarations_of_0_must_have_identical_constraints, name); + } + } + } + } + registerForUnusedIdentifiersCheck(node); + } + + function checkTemplateLiteralType(node: TemplateLiteralTypeNode) { + for (const span of node.templateSpans) { + checkSourceElement(span.type); + const type = getTypeFromTypeNode(span.type); + checkTypeAssignableTo(type, templateConstraintType, span.type); + } + getTypeFromTypeNode(node); + } + + function checkImportType(node: ImportTypeNode) { + checkSourceElement(node.argument); + + if (node.attributes) { + getResolutionModeOverride(node.attributes, grammarErrorOnNode); + } + checkTypeReferenceOrImport(node); + } + + function checkNamedTupleMember(node: NamedTupleMember) { + if (node.dotDotDotToken && node.questionToken) { + grammarErrorOnNode(node, Diagnostics.A_tuple_member_cannot_be_both_optional_and_rest); + } + if (node.type.kind === SyntaxKind.OptionalType) { + grammarErrorOnNode(node.type, Diagnostics.A_labeled_tuple_element_is_declared_as_optional_with_a_question_mark_after_the_name_and_before_the_colon_rather_than_after_the_type); + } + if (node.type.kind === SyntaxKind.RestType) { + grammarErrorOnNode(node.type, Diagnostics.A_labeled_tuple_element_is_declared_as_rest_with_a_before_the_name_rather_than_before_the_type); + } + checkSourceElement(node.type); + getTypeFromTypeNode(node); + } + + function isPrivateWithinAmbient(node: Node): boolean { + return (hasEffectiveModifier(node, ModifierFlags.Private) || isPrivateIdentifierClassElementDeclaration(node)) && !!(node.flags & NodeFlags.Ambient); + } + + function getEffectiveDeclarationFlags(n: Declaration, flagsToCheck: ModifierFlags): ModifierFlags { + let flags = getCombinedModifierFlagsCached(n); + + // children of classes (even ambient classes) should not be marked as ambient or export + // because those flags have no useful semantics there. + if ( + n.parent.kind !== SyntaxKind.InterfaceDeclaration && + n.parent.kind !== SyntaxKind.ClassDeclaration && + n.parent.kind !== SyntaxKind.ClassExpression && + n.flags & NodeFlags.Ambient + ) { + const container = getEnclosingContainer(n); + if ((container && container.flags & NodeFlags.ExportContext) && !(flags & ModifierFlags.Ambient) && !(isModuleBlock(n.parent) && isModuleDeclaration(n.parent.parent) && isGlobalScopeAugmentation(n.parent.parent))) { + // It is nested in an ambient export context, which means it is automatically exported + flags |= ModifierFlags.Export; + } + flags |= ModifierFlags.Ambient; + } + + return flags & flagsToCheck; + } + + function checkFunctionOrConstructorSymbol(symbol: Symbol): void { + addLazyDiagnostic(() => checkFunctionOrConstructorSymbolWorker(symbol)); + } + + function checkFunctionOrConstructorSymbolWorker(symbol: Symbol): void { + function getCanonicalOverload(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined): Declaration { + // Consider the canonical set of flags to be the flags of the bodyDeclaration or the first declaration + // Error on all deviations from this canonical set of flags + // The caveat is that if some overloads are defined in lib.d.ts, we don't want to + // report the errors on those. To achieve this, we will say that the implementation is + // the canonical signature only if it is in the same container as the first overload + const implementationSharesContainerWithFirstOverload = implementation !== undefined && implementation.parent === overloads[0].parent; + return implementationSharesContainerWithFirstOverload ? implementation : overloads[0]; + } + + function checkFlagAgreementBetweenOverloads(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined, flagsToCheck: ModifierFlags, someOverloadFlags: ModifierFlags, allOverloadFlags: ModifierFlags): void { + // Error if some overloads have a flag that is not shared by all overloads. To find the + // deviations, we XOR someOverloadFlags with allOverloadFlags + const someButNotAllOverloadFlags = someOverloadFlags ^ allOverloadFlags; + if (someButNotAllOverloadFlags !== 0) { + const canonicalFlags = getEffectiveDeclarationFlags(getCanonicalOverload(overloads, implementation), flagsToCheck); + forEach(overloads, o => { + const deviation = getEffectiveDeclarationFlags(o, flagsToCheck) ^ canonicalFlags; + if (deviation & ModifierFlags.Export) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_exported_or_non_exported); + } + else if (deviation & ModifierFlags.Ambient) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_ambient_or_non_ambient); + } + else if (deviation & (ModifierFlags.Private | ModifierFlags.Protected)) { + error(getNameOfDeclaration(o) || o, Diagnostics.Overload_signatures_must_all_be_public_private_or_protected); + } + else if (deviation & ModifierFlags.Abstract) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_abstract_or_non_abstract); + } + }); + } + } + + function checkQuestionTokenAgreementBetweenOverloads(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined, someHaveQuestionToken: boolean, allHaveQuestionToken: boolean): void { + if (someHaveQuestionToken !== allHaveQuestionToken) { + const canonicalHasQuestionToken = hasQuestionToken(getCanonicalOverload(overloads, implementation)); + forEach(overloads, o => { + const deviation = hasQuestionToken(o) !== canonicalHasQuestionToken; + if (deviation) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_optional_or_required); + } + }); + } + } + + const flagsToCheck: ModifierFlags = ModifierFlags.Export | ModifierFlags.Ambient | ModifierFlags.Private | ModifierFlags.Protected | ModifierFlags.Abstract; + let someNodeFlags: ModifierFlags = ModifierFlags.None; + let allNodeFlags = flagsToCheck; + let someHaveQuestionToken = false; + let allHaveQuestionToken = true; + let hasOverloads = false; + let bodyDeclaration: FunctionLikeDeclaration | undefined; + let lastSeenNonAmbientDeclaration: FunctionLikeDeclaration | undefined; + let previousDeclaration: SignatureDeclaration | undefined; + + const declarations = symbol.declarations; + const isConstructor = (symbol.flags & SymbolFlags.Constructor) !== 0; + + function reportImplementationExpectedError(node: SignatureDeclaration): void { + if (node.name && nodeIsMissing(node.name)) { + return; + } + + let seen = false; + const subsequentNode = forEachChild(node.parent, c => { + if (seen) { + return c; + } + else { + seen = c === node; + } + }); + // We may be here because of some extra nodes between overloads that could not be parsed into a valid node. + // In this case the subsequent node is not really consecutive (.pos !== node.end), and we must ignore it here. + if (subsequentNode && subsequentNode.pos === node.end) { + if (subsequentNode.kind === node.kind) { + const errorNode: Node = (subsequentNode as FunctionLikeDeclaration).name || subsequentNode; + const subsequentName = (subsequentNode as FunctionLikeDeclaration).name; + if ( + node.name && subsequentName && ( + // both are private identifiers + isPrivateIdentifier(node.name) && isPrivateIdentifier(subsequentName) && node.name.escapedText === subsequentName.escapedText || + // Both are computed property names + isComputedPropertyName(node.name) && isComputedPropertyName(subsequentName) && isTypeIdenticalTo(checkComputedPropertyName(node.name), checkComputedPropertyName(subsequentName)) || + // Both are literal property names that are the same. + isPropertyNameLiteral(node.name) && isPropertyNameLiteral(subsequentName) && + getEscapedTextOfIdentifierOrLiteral(node.name) === getEscapedTextOfIdentifierOrLiteral(subsequentName) + ) + ) { + const reportError = (node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature) && + isStatic(node) !== isStatic(subsequentNode); + // we can get here in two cases + // 1. mixed static and instance class members + // 2. something with the same name was defined before the set of overloads that prevents them from merging + // here we'll report error only for the first case since for second we should already report error in binder + if (reportError) { + const diagnostic = isStatic(node) ? Diagnostics.Function_overload_must_be_static : Diagnostics.Function_overload_must_not_be_static; + error(errorNode, diagnostic); + } + return; + } + if (nodeIsPresent((subsequentNode as FunctionLikeDeclaration).body)) { + error(errorNode, Diagnostics.Function_implementation_name_must_be_0, declarationNameToString(node.name)); + return; + } + } + } + const errorNode: Node = node.name || node; + if (isConstructor) { + error(errorNode, Diagnostics.Constructor_implementation_is_missing); + } + else { + // Report different errors regarding non-consecutive blocks of declarations depending on whether + // the node in question is abstract. + if (hasSyntacticModifier(node, ModifierFlags.Abstract)) { + error(errorNode, Diagnostics.All_declarations_of_an_abstract_method_must_be_consecutive); + } + else { + error(errorNode, Diagnostics.Function_implementation_is_missing_or_not_immediately_following_the_declaration); + } + } + } + + let duplicateFunctionDeclaration = false; + let multipleConstructorImplementation = false; + let hasNonAmbientClass = false; + const functionDeclarations = [] as Declaration[]; + if (declarations) { + for (const current of declarations) { + const node = current as SignatureDeclaration | ClassDeclaration | ClassExpression; + const inAmbientContext = node.flags & NodeFlags.Ambient; + const inAmbientContextOrInterface = node.parent && (node.parent.kind === SyntaxKind.InterfaceDeclaration || node.parent.kind === SyntaxKind.TypeLiteral) || inAmbientContext; + if (inAmbientContextOrInterface) { + // check if declarations are consecutive only if they are non-ambient + // 1. ambient declarations can be interleaved + // i.e. this is legal + // declare function foo(); + // declare function bar(); + // declare function foo(); + // 2. mixing ambient and non-ambient declarations is a separate error that will be reported - do not want to report an extra one + previousDeclaration = undefined; + } + + if ((node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression) && !inAmbientContext) { + hasNonAmbientClass = true; + } + + if (node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature || node.kind === SyntaxKind.Constructor) { + functionDeclarations.push(node); + const currentNodeFlags = getEffectiveDeclarationFlags(node, flagsToCheck); + someNodeFlags |= currentNodeFlags; + allNodeFlags &= currentNodeFlags; + someHaveQuestionToken = someHaveQuestionToken || hasQuestionToken(node); + allHaveQuestionToken = allHaveQuestionToken && hasQuestionToken(node); + const bodyIsPresent = nodeIsPresent((node as FunctionLikeDeclaration).body); + + if (bodyIsPresent && bodyDeclaration) { + if (isConstructor) { + multipleConstructorImplementation = true; + } + else { + duplicateFunctionDeclaration = true; + } + } + else if (previousDeclaration?.parent === node.parent && previousDeclaration.end !== node.pos) { + reportImplementationExpectedError(previousDeclaration); + } + + if (bodyIsPresent) { + if (!bodyDeclaration) { + bodyDeclaration = node as FunctionLikeDeclaration; + } + } + else { + hasOverloads = true; + } + + previousDeclaration = node; + + if (!inAmbientContextOrInterface) { + lastSeenNonAmbientDeclaration = node as FunctionLikeDeclaration; + } + } + if (isInJSFile(current) && isFunctionLike(current) && current.jsDoc) { + hasOverloads = length(getJSDocOverloadTags(current)) > 0; + } + } + } + + if (multipleConstructorImplementation) { + forEach(functionDeclarations, declaration => { + error(declaration, Diagnostics.Multiple_constructor_implementations_are_not_allowed); + }); + } + + if (duplicateFunctionDeclaration) { + forEach(functionDeclarations, declaration => { + error(getNameOfDeclaration(declaration) || declaration, Diagnostics.Duplicate_function_implementation); + }); + } + + if (hasNonAmbientClass && !isConstructor && symbol.flags & SymbolFlags.Function && declarations) { + const relatedDiagnostics = filter(declarations, d => d.kind === SyntaxKind.ClassDeclaration) + .map(d => createDiagnosticForNode(d, Diagnostics.Consider_adding_a_declare_modifier_to_this_class)); + + forEach(declarations, declaration => { + const diagnostic = declaration.kind === SyntaxKind.ClassDeclaration + ? Diagnostics.Class_declaration_cannot_implement_overload_list_for_0 + : declaration.kind === SyntaxKind.FunctionDeclaration + ? Diagnostics.Function_with_bodies_can_only_merge_with_classes_that_are_ambient + : undefined; + if (diagnostic) { + addRelatedInfo( + error(getNameOfDeclaration(declaration) || declaration, diagnostic, symbolName(symbol)), + ...relatedDiagnostics, + ); + } + }); + } + + // Abstract methods can't have an implementation -- in particular, they don't need one. + if ( + lastSeenNonAmbientDeclaration && !lastSeenNonAmbientDeclaration.body && + !hasSyntacticModifier(lastSeenNonAmbientDeclaration, ModifierFlags.Abstract) && !lastSeenNonAmbientDeclaration.questionToken + ) { + reportImplementationExpectedError(lastSeenNonAmbientDeclaration); + } + + if (hasOverloads) { + if (declarations) { + checkFlagAgreementBetweenOverloads(declarations, bodyDeclaration, flagsToCheck, someNodeFlags, allNodeFlags); + checkQuestionTokenAgreementBetweenOverloads(declarations, bodyDeclaration, someHaveQuestionToken, allHaveQuestionToken); + } + + if (bodyDeclaration) { + const signatures = getSignaturesOfSymbol(symbol); + const bodySignature = getSignatureFromDeclaration(bodyDeclaration); + for (const signature of signatures) { + if (!isImplementationCompatibleWithOverload(bodySignature, signature)) { + const errorNode = signature.declaration && isJSDocSignature(signature.declaration) + ? (signature.declaration.parent as JSDocOverloadTag | JSDocCallbackTag).tagName + : signature.declaration; + addRelatedInfo( + error(errorNode, Diagnostics.This_overload_signature_is_not_compatible_with_its_implementation_signature), + createDiagnosticForNode(bodyDeclaration, Diagnostics.The_implementation_signature_is_declared_here), + ); + break; + } + } + } + } + } + + function checkExportsOnMergedDeclarations(node: Declaration): void { + addLazyDiagnostic(() => checkExportsOnMergedDeclarationsWorker(node)); + } + + function checkExportsOnMergedDeclarationsWorker(node: Declaration): void { + // if localSymbol is defined on node then node itself is exported - check is required + let symbol = node.localSymbol; + if (!symbol) { + // local symbol is undefined => this declaration is non-exported. + // however symbol might contain other declarations that are exported + symbol = getSymbolOfDeclaration(node)!; + if (!symbol.exportSymbol) { + // this is a pure local symbol (all declarations are non-exported) - no need to check anything + return; + } + } + + // run the check only for the first declaration in the list + if (getDeclarationOfKind(symbol, node.kind) !== node) { + return; + } + + let exportedDeclarationSpaces = DeclarationSpaces.None; + let nonExportedDeclarationSpaces = DeclarationSpaces.None; + let defaultExportedDeclarationSpaces = DeclarationSpaces.None; + for (const d of symbol.declarations!) { + const declarationSpaces = getDeclarationSpaces(d); + const effectiveDeclarationFlags = getEffectiveDeclarationFlags(d, ModifierFlags.Export | ModifierFlags.Default); + + if (effectiveDeclarationFlags & ModifierFlags.Export) { + if (effectiveDeclarationFlags & ModifierFlags.Default) { + defaultExportedDeclarationSpaces |= declarationSpaces; + } + else { + exportedDeclarationSpaces |= declarationSpaces; + } + } + else { + nonExportedDeclarationSpaces |= declarationSpaces; + } + } + + // Spaces for anything not declared a 'default export'. + const nonDefaultExportedDeclarationSpaces = exportedDeclarationSpaces | nonExportedDeclarationSpaces; + + const commonDeclarationSpacesForExportsAndLocals = exportedDeclarationSpaces & nonExportedDeclarationSpaces; + const commonDeclarationSpacesForDefaultAndNonDefault = defaultExportedDeclarationSpaces & nonDefaultExportedDeclarationSpaces; + + if (commonDeclarationSpacesForExportsAndLocals || commonDeclarationSpacesForDefaultAndNonDefault) { + // declaration spaces for exported and non-exported declarations intersect + for (const d of symbol.declarations!) { + const declarationSpaces = getDeclarationSpaces(d); + + const name = getNameOfDeclaration(d); + // Only error on the declarations that contributed to the intersecting spaces. + if (declarationSpaces & commonDeclarationSpacesForDefaultAndNonDefault) { + error(name, Diagnostics.Merged_declaration_0_cannot_include_a_default_export_declaration_Consider_adding_a_separate_export_default_0_declaration_instead, declarationNameToString(name)); + } + else if (declarationSpaces & commonDeclarationSpacesForExportsAndLocals) { + error(name, Diagnostics.Individual_declarations_in_merged_declaration_0_must_be_all_exported_or_all_local, declarationNameToString(name)); + } + } + } + + function getDeclarationSpaces(decl: Declaration): DeclarationSpaces { + let d = decl as Node; + switch (d.kind) { + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + + // A jsdoc typedef and callback are, by definition, type aliases. + // falls through + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.JSDocEnumTag: + return DeclarationSpaces.ExportType; + case SyntaxKind.ModuleDeclaration: + return isAmbientModule(d as ModuleDeclaration) || getModuleInstanceState(d as ModuleDeclaration) !== ModuleInstanceState.NonInstantiated + ? DeclarationSpaces.ExportNamespace | DeclarationSpaces.ExportValue + : DeclarationSpaces.ExportNamespace; + case SyntaxKind.ClassDeclaration: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.EnumMember: + return DeclarationSpaces.ExportType | DeclarationSpaces.ExportValue; + case SyntaxKind.SourceFile: + return DeclarationSpaces.ExportType | DeclarationSpaces.ExportValue | DeclarationSpaces.ExportNamespace; + case SyntaxKind.ExportAssignment: + case SyntaxKind.BinaryExpression: + const node = d as ExportAssignment | BinaryExpression; + const expression = isExportAssignment(node) ? node.expression : node.right; + // Export assigned entity name expressions act as aliases and should fall through, otherwise they export values + if (!isEntityNameExpression(expression)) { + return DeclarationSpaces.ExportValue; + } + d = expression; + + // The below options all declare an Alias, which is allowed to merge with other values within the importing module. + // falls through + case SyntaxKind.ImportEqualsDeclaration: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportClause: + let result = DeclarationSpaces.None; + const target = resolveAlias(getSymbolOfDeclaration(d as ImportEqualsDeclaration | NamespaceImport | ImportClause | ExportAssignment | BinaryExpression)); + forEach(target.declarations, d => { + result |= getDeclarationSpaces(d); + }); + return result; + case SyntaxKind.VariableDeclaration: + case SyntaxKind.BindingElement: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.ImportSpecifier: // https://github.com/Microsoft/TypeScript/pull/7591 + case SyntaxKind.Identifier: // https://github.com/microsoft/TypeScript/issues/36098 + // Identifiers are used as declarations of assignment declarations whose parents may be + // SyntaxKind.CallExpression - `Object.defineProperty(thing, "aField", {value: 42});` + // SyntaxKind.ElementAccessExpression - `thing["aField"] = 42;` or `thing["aField"];` (with a doc comment on it) + // or SyntaxKind.PropertyAccessExpression - `thing.aField = 42;` + // all of which are pretty much always values, or at least imply a value meaning. + // It may be apprpriate to treat these as aliases in the future. + return DeclarationSpaces.ExportValue; + case SyntaxKind.MethodSignature: + case SyntaxKind.PropertySignature: + return DeclarationSpaces.ExportType; + default: + return Debug.failBadSyntaxKind(d); + } + } + } + + function getAwaitedTypeOfPromise(type: Type, errorNode?: Node, diagnosticMessage?: DiagnosticMessage, ...args: DiagnosticArguments): Type | undefined { + const promisedType = getPromisedTypeOfPromise(type, errorNode); + return promisedType && getAwaitedType(promisedType, errorNode, diagnosticMessage, ...args); + } + + /** + * Gets the "promised type" of a promise. + * @param type The type of the promise. + * @remarks The "promised type" of a type is the type of the "value" parameter of the "onfulfilled" callback. + */ + function getPromisedTypeOfPromise(type: Type, errorNode?: Node, thisTypeForErrorOut?: { value?: Type; }): Type | undefined { + // + // { // type + // then( // thenFunction + // onfulfilled: ( // onfulfilledParameterType + // value: T // valueParameterType + // ) => any + // ): any; + // } + // + + if (isTypeAny(type)) { + return undefined; + } + + const typeAsPromise = type as PromiseOrAwaitableType; + if (typeAsPromise.promisedTypeOfPromise) { + return typeAsPromise.promisedTypeOfPromise; + } + + if (isReferenceToType(type, getGlobalPromiseType(/*reportErrors*/ false))) { + return typeAsPromise.promisedTypeOfPromise = getTypeArguments(type as GenericType)[0]; + } + + // primitives with a `{ then() }` won't be unwrapped/adopted. + if (allTypesAssignableToKind(getBaseConstraintOrType(type), TypeFlags.Primitive | TypeFlags.Never)) { + return undefined; + } + + const thenFunction = getTypeOfPropertyOfType(type, "then" as __String)!; // TODO: GH#18217 + if (isTypeAny(thenFunction)) { + return undefined; + } + + const thenSignatures = thenFunction ? getSignaturesOfType(thenFunction, SignatureKind.Call) : emptyArray; + if (thenSignatures.length === 0) { + if (errorNode) { + error(errorNode, Diagnostics.A_promise_must_have_a_then_method); + } + return undefined; + } + + let thisTypeForError: Type | undefined; + let candidates: Signature[] | undefined; + for (const thenSignature of thenSignatures) { + const thisType = getThisTypeOfSignature(thenSignature); + if (thisType && thisType !== voidType && !isTypeRelatedTo(type, thisType, subtypeRelation)) { + thisTypeForError = thisType; + } + else { + candidates = append(candidates, thenSignature); + } + } + + if (!candidates) { + Debug.assertIsDefined(thisTypeForError); + if (thisTypeForErrorOut) { + thisTypeForErrorOut.value = thisTypeForError; + } + if (errorNode) { + error(errorNode, Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1, typeToString(type), typeToString(thisTypeForError)); + } + return undefined; + } + + const onfulfilledParameterType = getTypeWithFacts(getUnionType(map(candidates, getTypeOfFirstParameterOfSignature)), TypeFacts.NEUndefinedOrNull); + if (isTypeAny(onfulfilledParameterType)) { + return undefined; + } + + const onfulfilledParameterSignatures = getSignaturesOfType(onfulfilledParameterType, SignatureKind.Call); + if (onfulfilledParameterSignatures.length === 0) { + if (errorNode) { + error(errorNode, Diagnostics.The_first_parameter_of_the_then_method_of_a_promise_must_be_a_callback); + } + return undefined; + } + + return typeAsPromise.promisedTypeOfPromise = getUnionType(map(onfulfilledParameterSignatures, getTypeOfFirstParameterOfSignature), UnionReduction.Subtype); + } + + /** + * Gets the "awaited type" of a type. + * @param type The type to await. + * @param withAlias When `true`, wraps the "awaited type" in `Awaited` if needed. + * @remarks The "awaited type" of an expression is its "promised type" if the expression is a + * Promise-like type; otherwise, it is the type of the expression. This is used to reflect + * The runtime behavior of the `await` keyword. + */ + function checkAwaitedType(type: Type, withAlias: boolean, errorNode: Node, diagnosticMessage: DiagnosticMessage, ...args: DiagnosticArguments): Type { + const awaitedType = withAlias ? + getAwaitedType(type, errorNode, diagnosticMessage, ...args) : + getAwaitedTypeNoAlias(type, errorNode, diagnosticMessage, ...args); + return awaitedType || errorType; + } + + /** + * Determines whether a type is an object with a callable `then` member. + */ + function isThenableType(type: Type): boolean { + if (allTypesAssignableToKind(getBaseConstraintOrType(type), TypeFlags.Primitive | TypeFlags.Never)) { + // primitive types cannot be considered "thenable" since they are not objects. + return false; + } + + const thenFunction = getTypeOfPropertyOfType(type, "then" as __String); + return !!thenFunction && getSignaturesOfType(getTypeWithFacts(thenFunction, TypeFacts.NEUndefinedOrNull), SignatureKind.Call).length > 0; + } + + interface AwaitedTypeInstantiation extends Type { + _awaitedTypeBrand: never; + aliasSymbol: Symbol; + aliasTypeArguments: readonly Type[]; + } + + function isAwaitedTypeInstantiation(type: Type): type is AwaitedTypeInstantiation { + if (type.flags & TypeFlags.Conditional) { + const awaitedSymbol = getGlobalAwaitedSymbol(/*reportErrors*/ false); + return !!awaitedSymbol && type.aliasSymbol === awaitedSymbol && type.aliasTypeArguments?.length === 1; + } + return false; + } + + /** + * For a generic `Awaited`, gets `T`. + */ + function unwrapAwaitedType(type: Type) { + return type.flags & TypeFlags.Union ? mapType(type, unwrapAwaitedType) : + isAwaitedTypeInstantiation(type) ? type.aliasTypeArguments[0] : + type; + } + + function isAwaitedTypeNeeded(type: Type) { + // If this is already an `Awaited`, we shouldn't wrap it. This helps to avoid `Awaited>` in higher-order. + if (isTypeAny(type) || isAwaitedTypeInstantiation(type)) { + return false; + } + + // We only need `Awaited` if `T` contains possibly non-primitive types. + if (isGenericObjectType(type)) { + const baseConstraint = getBaseConstraintOfType(type); + // We only need `Awaited` if `T` is a type variable that has no base constraint, or the base constraint of `T` is `any`, `unknown`, `{}`, `object`, + // or is promise-like. + if ( + baseConstraint ? + baseConstraint.flags & TypeFlags.AnyOrUnknown || isEmptyObjectType(baseConstraint) || someType(baseConstraint, isThenableType) : + maybeTypeOfKind(type, TypeFlags.TypeVariable) + ) { + return true; + } + } + + return false; + } + + function tryCreateAwaitedType(type: Type): Type | undefined { + // Nothing to do if `Awaited` doesn't exist + const awaitedSymbol = getGlobalAwaitedSymbol(/*reportErrors*/ true); + if (awaitedSymbol) { + // Unwrap unions that may contain `Awaited`, otherwise its possible to manufacture an `Awaited | U>` where + // an `Awaited` would suffice. + return getTypeAliasInstantiation(awaitedSymbol, [unwrapAwaitedType(type)]); + } + + return undefined; + } + + function createAwaitedTypeIfNeeded(type: Type): Type { + // We wrap type `T` in `Awaited` based on the following conditions: + // - `T` is not already an `Awaited`, and + // - `T` is generic, and + // - One of the following applies: + // - `T` has no base constraint, or + // - The base constraint of `T` is `any`, `unknown`, `object`, or `{}`, or + // - The base constraint of `T` is an object type with a callable `then` method. + + if (isAwaitedTypeNeeded(type)) { + return tryCreateAwaitedType(type) ?? type; + } + + Debug.assert(isAwaitedTypeInstantiation(type) || getPromisedTypeOfPromise(type) === undefined, "type provided should not be a non-generic 'promise'-like."); + return type; + } + + /** + * Gets the "awaited type" of a type. + * + * The "awaited type" of an expression is its "promised type" if the expression is a + * Promise-like type; otherwise, it is the type of the expression. If the "promised + * type" is itself a Promise-like, the "promised type" is recursively unwrapped until a + * non-promise type is found. + * + * This is used to reflect the runtime behavior of the `await` keyword. + */ + function getAwaitedType(type: Type, errorNode?: Node, diagnosticMessage?: DiagnosticMessage, ...args: DiagnosticArguments): Type | undefined { + const awaitedType = getAwaitedTypeNoAlias(type, errorNode, diagnosticMessage, ...args); + return awaitedType && createAwaitedTypeIfNeeded(awaitedType); + } + + /** + * Gets the "awaited type" of a type without introducing an `Awaited` wrapper. + * + * @see {@link getAwaitedType} + */ + function getAwaitedTypeNoAlias(type: Type, errorNode?: Node, diagnosticMessage?: DiagnosticMessage, ...args: DiagnosticArguments): Type | undefined { + if (isTypeAny(type)) { + return type; + } + + // If this is already an `Awaited`, just return it. This avoids `Awaited>` in higher-order + if (isAwaitedTypeInstantiation(type)) { + return type; + } + + // If we've already cached an awaited type, return a possible `Awaited` for it. + const typeAsAwaitable = type as PromiseOrAwaitableType; + if (typeAsAwaitable.awaitedTypeOfType) { + return typeAsAwaitable.awaitedTypeOfType; + } + + // For a union, get a union of the awaited types of each constituent. + if (type.flags & TypeFlags.Union) { + if (awaitedTypeStack.lastIndexOf(type.id) >= 0) { + if (errorNode) { + error(errorNode, Diagnostics.Type_is_referenced_directly_or_indirectly_in_the_fulfillment_callback_of_its_own_then_method); + } + return undefined; + } + + const mapper = errorNode ? (constituentType: Type) => getAwaitedTypeNoAlias(constituentType, errorNode, diagnosticMessage, ...args) : getAwaitedTypeNoAlias; + + awaitedTypeStack.push(type.id); + const mapped = mapType(type, mapper); + awaitedTypeStack.pop(); + + return typeAsAwaitable.awaitedTypeOfType = mapped; + } + + // If `type` is generic and should be wrapped in `Awaited`, return it. + if (isAwaitedTypeNeeded(type)) { + return typeAsAwaitable.awaitedTypeOfType = type; + } + + const thisTypeForErrorOut: { value: Type | undefined; } = { value: undefined }; + const promisedType = getPromisedTypeOfPromise(type, /*errorNode*/ undefined, thisTypeForErrorOut); + if (promisedType) { + if (type.id === promisedType.id || awaitedTypeStack.lastIndexOf(promisedType.id) >= 0) { + // Verify that we don't have a bad actor in the form of a promise whose + // promised type is the same as the promise type, or a mutually recursive + // promise. If so, we return undefined as we cannot guess the shape. If this + // were the actual case in the JavaScript, this Promise would never resolve. + // + // An example of a bad actor with a singly-recursive promise type might + // be: + // + // interface BadPromise { + // then( + // onfulfilled: (value: BadPromise) => any, + // onrejected: (error: any) => any): BadPromise; + // } + // + // The above interface will pass the PromiseLike check, and return a + // promised type of `BadPromise`. Since this is a self reference, we + // don't want to keep recursing ad infinitum. + // + // An example of a bad actor in the form of a mutually-recursive + // promise type might be: + // + // interface BadPromiseA { + // then( + // onfulfilled: (value: BadPromiseB) => any, + // onrejected: (error: any) => any): BadPromiseB; + // } + // + // interface BadPromiseB { + // then( + // onfulfilled: (value: BadPromiseA) => any, + // onrejected: (error: any) => any): BadPromiseA; + // } + // + if (errorNode) { + error(errorNode, Diagnostics.Type_is_referenced_directly_or_indirectly_in_the_fulfillment_callback_of_its_own_then_method); + } + return undefined; + } + + // Keep track of the type we're about to unwrap to avoid bad recursive promise types. + // See the comments above for more information. + awaitedTypeStack.push(type.id); + const awaitedType = getAwaitedTypeNoAlias(promisedType, errorNode, diagnosticMessage, ...args); + awaitedTypeStack.pop(); + + if (!awaitedType) { + return undefined; + } + + return typeAsAwaitable.awaitedTypeOfType = awaitedType; + } + + // The type was not a promise, so it could not be unwrapped any further. + // As long as the type does not have a callable "then" property, it is + // safe to return the type; otherwise, an error is reported and we return + // undefined. + // + // An example of a non-promise "thenable" might be: + // + // await { then(): void {} } + // + // The "thenable" does not match the minimal definition for a promise. When + // a Promise/A+-compatible or ES6 promise tries to adopt this value, the promise + // will never settle. We treat this as an error to help flag an early indicator + // of a runtime problem. If the user wants to return this value from an async + // function, they would need to wrap it in some other value. If they want it to + // be treated as a promise, they can cast to . + if (isThenableType(type)) { + if (errorNode) { + Debug.assertIsDefined(diagnosticMessage); + let chain: DiagnosticMessageChain | undefined; + if (thisTypeForErrorOut.value) { + chain = chainDiagnosticMessages(chain, Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1, typeToString(type), typeToString(thisTypeForErrorOut.value)); + } + chain = chainDiagnosticMessages(chain, diagnosticMessage, ...args); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorNode), errorNode, chain)); + } + return undefined; + } + + return typeAsAwaitable.awaitedTypeOfType = type; + } + + /** + * Checks the return type of an async function to ensure it is a compatible + * Promise implementation. + * + * This checks that an async function has a valid Promise-compatible return type. + * An async function has a valid Promise-compatible return type if the resolved value + * of the return type has a construct signature that takes in an `initializer` function + * that in turn supplies a `resolve` function as one of its arguments and results in an + * object with a callable `then` signature. + * + * @param node The signature to check + */ + function checkAsyncFunctionReturnType(node: FunctionLikeDeclaration | MethodSignature, returnTypeNode: TypeNode, returnTypeErrorLocation: TypeNode) { + // As part of our emit for an async function, we will need to emit the entity name of + // the return type annotation as an expression. To meet the necessary runtime semantics + // for __awaiter, we must also check that the type of the declaration (e.g. the static + // side or "constructor" of the promise type) is compatible `PromiseConstructorLike`. + // + // An example might be (from lib.es6.d.ts): + // + // interface Promise { ... } + // interface PromiseConstructor { + // new (...): Promise; + // } + // declare var Promise: PromiseConstructor; + // + // When an async function declares a return type annotation of `Promise`, we + // need to get the type of the `Promise` variable declaration above, which would + // be `PromiseConstructor`. + // + // The same case applies to a class: + // + // declare class Promise { + // constructor(...); + // then(...): Promise; + // } + // + const returnType = getTypeFromTypeNode(returnTypeNode); + if (languageVersion >= ScriptTarget.ES2015) { + if (isErrorType(returnType)) { + return; + } + const globalPromiseType = getGlobalPromiseType(/*reportErrors*/ true); + if (globalPromiseType !== emptyGenericType && !isReferenceToType(returnType, globalPromiseType)) { + // The promise type was not a valid type reference to the global promise type, so we + // report an error and return the unknown type. + reportErrorForInvalidReturnType(Diagnostics.The_return_type_of_an_async_function_or_method_must_be_the_global_Promise_T_type_Did_you_mean_to_write_Promise_0, returnTypeNode, returnTypeErrorLocation, typeToString(getAwaitedTypeNoAlias(returnType) || voidType)); + return; + } + } + else { + // Always mark the type node as referenced if it points to a value + markLinkedReferences(node, ReferenceHint.AsyncFunction); + if (isErrorType(returnType)) { + return; + } + + const promiseConstructorName = getEntityNameFromTypeNode(returnTypeNode); + if (promiseConstructorName === undefined) { + reportErrorForInvalidReturnType(Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_because_it_does_not_refer_to_a_Promise_compatible_constructor_value, returnTypeNode, returnTypeErrorLocation, typeToString(returnType)); + return; + } + + const promiseConstructorSymbol = resolveEntityName(promiseConstructorName, SymbolFlags.Value, /*ignoreErrors*/ true); + const promiseConstructorType = promiseConstructorSymbol ? getTypeOfSymbol(promiseConstructorSymbol) : errorType; + if (isErrorType(promiseConstructorType)) { + if (promiseConstructorName.kind === SyntaxKind.Identifier && promiseConstructorName.escapedText === "Promise" && getTargetType(returnType) === getGlobalPromiseType(/*reportErrors*/ false)) { + error(returnTypeErrorLocation, Diagnostics.An_async_function_or_method_in_ES5_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option); + } + else { + reportErrorForInvalidReturnType(Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_because_it_does_not_refer_to_a_Promise_compatible_constructor_value, returnTypeNode, returnTypeErrorLocation, entityNameToString(promiseConstructorName)); + } + return; + } + + const globalPromiseConstructorLikeType = getGlobalPromiseConstructorLikeType(/*reportErrors*/ true); + if (globalPromiseConstructorLikeType === emptyObjectType) { + // If we couldn't resolve the global PromiseConstructorLike type we cannot verify + // compatibility with __awaiter. + reportErrorForInvalidReturnType(Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_because_it_does_not_refer_to_a_Promise_compatible_constructor_value, returnTypeNode, returnTypeErrorLocation, entityNameToString(promiseConstructorName)); + return; + } + + const headMessage = Diagnostics.Type_0_is_not_a_valid_async_function_return_type_in_ES5_because_it_does_not_refer_to_a_Promise_compatible_constructor_value; + const errorInfo = () => returnTypeNode === returnTypeErrorLocation ? undefined : chainDiagnosticMessages(/*details*/ undefined, Diagnostics.The_return_type_of_an_async_function_or_method_must_be_the_global_Promise_T_type); + if (!checkTypeAssignableTo(promiseConstructorType, globalPromiseConstructorLikeType, returnTypeErrorLocation, headMessage, errorInfo)) { + return; + } + + // Verify there is no local declaration that could collide with the promise constructor. + const rootName = promiseConstructorName && getFirstIdentifier(promiseConstructorName); + const collidingSymbol = getSymbol(node.locals!, rootName.escapedText, SymbolFlags.Value); + if (collidingSymbol) { + error(collidingSymbol.valueDeclaration, Diagnostics.Duplicate_identifier_0_Compiler_uses_declaration_1_to_support_async_functions, idText(rootName), entityNameToString(promiseConstructorName)); + return; + } + } + + checkAwaitedType(returnType, /*withAlias*/ false, node, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); + + function reportErrorForInvalidReturnType(message: DiagnosticMessage, returnTypeNode: TypeNode, returnTypeErrorLocation: TypeNode, typeName: string) { + if (returnTypeNode === returnTypeErrorLocation) { + error(returnTypeErrorLocation, message, typeName); + } + else { + const diag = error(returnTypeErrorLocation, Diagnostics.The_return_type_of_an_async_function_or_method_must_be_the_global_Promise_T_type); + addRelatedInfo(diag, createDiagnosticForNode(returnTypeNode, message, typeName)); + } + } + } + + function checkGrammarDecorator(decorator: Decorator): boolean { + const sourceFile = getSourceFileOfNode(decorator); + if (!hasParseDiagnostics(sourceFile)) { + let node: Expression = decorator.expression; + + // DecoratorParenthesizedExpression : + // `(` Expression `)` + + if (isParenthesizedExpression(node)) { + return false; + } + + let canHaveCallExpression = true; + let errorNode: Node | undefined; + while (true) { + // Allow TS syntax such as non-null assertions and instantiation expressions + if (isExpressionWithTypeArguments(node) || isNonNullExpression(node)) { + node = node.expression; + continue; + } + + // DecoratorCallExpression : + // DecoratorMemberExpression Arguments + + if (isCallExpression(node)) { + if (!canHaveCallExpression) { + errorNode = node; + } + if (node.questionDotToken) { + // Even if we already have an error node, error at the `?.` token since it appears earlier. + errorNode = node.questionDotToken; + } + node = node.expression; + canHaveCallExpression = false; + continue; + } + + // DecoratorMemberExpression : + // IdentifierReference + // DecoratorMemberExpression `.` IdentifierName + // DecoratorMemberExpression `.` PrivateIdentifier + + if (isPropertyAccessExpression(node)) { + if (node.questionDotToken) { + // Even if we already have an error node, error at the `?.` token since it appears earlier. + errorNode = node.questionDotToken; + } + node = node.expression; + canHaveCallExpression = false; + continue; + } + + if (!isIdentifier(node)) { + // Even if we already have an error node, error at this node since it appears earlier. + errorNode = node; + } + + break; + } + + if (errorNode) { + addRelatedInfo( + error(decorator.expression, Diagnostics.Expression_must_be_enclosed_in_parentheses_to_be_used_as_a_decorator), + createDiagnosticForNode(errorNode, Diagnostics.Invalid_syntax_in_decorator), + ); + return true; + } + } + + return false; + } + + /** Check a decorator */ + function checkDecorator(node: Decorator): void { + checkGrammarDecorator(node); + + const signature = getResolvedSignature(node); + checkDeprecatedSignature(signature, node); + const returnType = getReturnTypeOfSignature(signature); + if (returnType.flags & TypeFlags.Any) { + return; + } + + // if we fail to get a signature and return type here, we will have already reported a grammar error in `checkDecorators`. + const decoratorSignature = getDecoratorCallSignature(node); + if (!decoratorSignature?.resolvedReturnType) return; + + let headMessage: DiagnosticMessage; + const expectedReturnType = decoratorSignature.resolvedReturnType; + switch (node.parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + headMessage = Diagnostics.Decorator_function_return_type_0_is_not_assignable_to_type_1; + break; + + case SyntaxKind.PropertyDeclaration: + if (!legacyDecorators) { + headMessage = Diagnostics.Decorator_function_return_type_0_is_not_assignable_to_type_1; + break; + } + // falls through + + case SyntaxKind.Parameter: + headMessage = Diagnostics.Decorator_function_return_type_is_0_but_is_expected_to_be_void_or_any; + break; + + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + headMessage = Diagnostics.Decorator_function_return_type_0_is_not_assignable_to_type_1; + break; + + default: + return Debug.failBadSyntaxKind(node.parent); + } + + checkTypeAssignableTo(returnType, expectedReturnType, node.expression, headMessage); + } + + /** + * Creates a synthetic `Signature` corresponding to a call signature. + */ + function createCallSignature( + typeParameters: readonly TypeParameter[] | undefined, + thisParameter: Symbol | undefined, + parameters: readonly Symbol[], + returnType: Type, + typePredicate?: TypePredicate, + minArgumentCount: number = parameters.length, + flags: SignatureFlags = SignatureFlags.None, + ) { + const decl = factory.createFunctionTypeNode(/*typeParameters*/ undefined, emptyArray, factory.createKeywordTypeNode(SyntaxKind.AnyKeyword)); + return createSignature(decl, typeParameters, thisParameter, parameters, returnType, typePredicate, minArgumentCount, flags); + } + + /** + * Creates a synthetic `FunctionType` + */ + function createFunctionType( + typeParameters: readonly TypeParameter[] | undefined, + thisParameter: Symbol | undefined, + parameters: readonly Symbol[], + returnType: Type, + typePredicate?: TypePredicate, + minArgumentCount?: number, + flags?: SignatureFlags, + ) { + const signature = createCallSignature(typeParameters, thisParameter, parameters, returnType, typePredicate, minArgumentCount, flags); + return getOrCreateTypeFromSignature(signature); + } + + function createGetterFunctionType(type: Type) { + return createFunctionType(/*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, type); + } + + function createSetterFunctionType(type: Type) { + const valueParam = createParameter("value" as __String, type); + return createFunctionType(/*typeParameters*/ undefined, /*thisParameter*/ undefined, [valueParam], voidType); + } + + function getEntityNameForDecoratorMetadata(node: TypeNode | undefined): EntityName | undefined { + if (node) { + switch (node.kind) { + case SyntaxKind.IntersectionType: + case SyntaxKind.UnionType: + return getEntityNameForDecoratorMetadataFromTypeList((node as UnionOrIntersectionTypeNode).types); + + case SyntaxKind.ConditionalType: + return getEntityNameForDecoratorMetadataFromTypeList([(node as ConditionalTypeNode).trueType, (node as ConditionalTypeNode).falseType]); + + case SyntaxKind.ParenthesizedType: + case SyntaxKind.NamedTupleMember: + return getEntityNameForDecoratorMetadata((node as ParenthesizedTypeNode).type); + + case SyntaxKind.TypeReference: + return (node as TypeReferenceNode).typeName; + } + } + } + + function getEntityNameForDecoratorMetadataFromTypeList(types: readonly TypeNode[]): EntityName | undefined { + let commonEntityName: EntityName | undefined; + for (let typeNode of types) { + while (typeNode.kind === SyntaxKind.ParenthesizedType || typeNode.kind === SyntaxKind.NamedTupleMember) { + typeNode = (typeNode as ParenthesizedTypeNode | NamedTupleMember).type; // Skip parens if need be + } + if (typeNode.kind === SyntaxKind.NeverKeyword) { + continue; // Always elide `never` from the union/intersection if possible + } + if (!strictNullChecks && (typeNode.kind === SyntaxKind.LiteralType && (typeNode as LiteralTypeNode).literal.kind === SyntaxKind.NullKeyword || typeNode.kind === SyntaxKind.UndefinedKeyword)) { + continue; // Elide null and undefined from unions for metadata, just like what we did prior to the implementation of strict null checks + } + const individualEntityName = getEntityNameForDecoratorMetadata(typeNode); + if (!individualEntityName) { + // Individual is something like string number + // So it would be serialized to either that type or object + // Safe to return here + return undefined; + } + + if (commonEntityName) { + // Note this is in sync with the transformation that happens for type node. + // Keep this in sync with serializeUnionOrIntersectionType + // Verify if they refer to same entity and is identifier + // return undefined if they dont match because we would emit object + if ( + !isIdentifier(commonEntityName) || + !isIdentifier(individualEntityName) || + commonEntityName.escapedText !== individualEntityName.escapedText + ) { + return undefined; + } + } + else { + commonEntityName = individualEntityName; + } + } + return commonEntityName; + } + + function getParameterTypeNodeForDecoratorCheck(node: ParameterDeclaration): TypeNode | undefined { + const typeNode = getEffectiveTypeAnnotationNode(node); + return isRestParameter(node) ? getRestParameterElementType(typeNode) : typeNode; + } + + /** Check the decorators of a node */ + function checkDecorators(node: Node): void { + // skip this check for nodes that cannot have decorators. These should have already had an error reported by + // checkGrammarModifiers. + if (!canHaveDecorators(node) || !hasDecorators(node) || !node.modifiers || !nodeCanBeDecorated(legacyDecorators, node, node.parent, node.parent.parent)) { + return; + } + + const firstDecorator = find(node.modifiers, isDecorator); + if (!firstDecorator) { + return; + } + + if (legacyDecorators) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Decorate); + if (node.kind === SyntaxKind.Parameter) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Param); + } + } + else if (languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.ESDecorateAndRunInitializers); + if (isClassDeclaration(node)) { + if (!node.name) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.SetFunctionName); + } + else { + const member = getFirstTransformableStaticClassElement(node); + if (member) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.SetFunctionName); + } + } + } + else if (!isClassExpression(node)) { + if (isPrivateIdentifier(node.name) && (isMethodDeclaration(node) || isAccessor(node) || isAutoAccessorPropertyDeclaration(node))) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.SetFunctionName); + } + if (isComputedPropertyName(node.name)) { + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.PropKey); + } + } + } + + markLinkedReferences(node, ReferenceHint.Decorator); + + for (const modifier of node.modifiers) { + if (isDecorator(modifier)) { + checkDecorator(modifier); + } + } + } + + function checkFunctionDeclaration(node: FunctionDeclaration): void { + addLazyDiagnostic(checkFunctionDeclarationDiagnostics); + + function checkFunctionDeclarationDiagnostics() { + checkFunctionOrMethodDeclaration(node); + checkGrammarForGenerator(node); + checkCollisionsForDeclarationName(node, node.name); + } + } + + function checkJSDocTypeAliasTag(node: JSDocTypedefTag | JSDocCallbackTag) { + if (!node.typeExpression) { + // If the node had `@property` tags, `typeExpression` would have been set to the first property tag. + error(node.name, Diagnostics.JSDoc_typedef_tag_should_either_have_a_type_annotation_or_be_followed_by_property_or_member_tags); + } + + if (node.name) { + checkTypeNameIsReserved(node.name, Diagnostics.Type_alias_name_cannot_be_0); + } + checkSourceElement(node.typeExpression); + checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); + } + + function checkJSDocTemplateTag(node: JSDocTemplateTag): void { + checkSourceElement(node.constraint); + for (const tp of node.typeParameters) { + checkSourceElement(tp); + } + } + + function checkJSDocTypeTag(node: JSDocTypeTag) { + checkSourceElement(node.typeExpression); + } + + function checkJSDocSatisfiesTag(node: JSDocSatisfiesTag) { + checkSourceElement(node.typeExpression); + const host = getEffectiveJSDocHost(node); + if (host) { + const tags = getAllJSDocTags(host, isJSDocSatisfiesTag); + if (length(tags) > 1) { + for (let i = 1; i < length(tags); i++) { + const tagName = tags[i].tagName; + error(tagName, Diagnostics._0_tag_already_specified, idText(tagName)); + } + } + } + } + + function checkJSDocLinkLikeTag(node: JSDocLink | JSDocLinkCode | JSDocLinkPlain) { + if (node.name) { + resolveJSDocMemberName(node.name, /*ignoreErrors*/ true); + } + } + + function checkJSDocParameterTag(node: JSDocParameterTag) { + checkSourceElement(node.typeExpression); + } + + function checkJSDocPropertyTag(node: JSDocPropertyTag) { + checkSourceElement(node.typeExpression); + } + + function checkJSDocFunctionType(node: JSDocFunctionType): void { + addLazyDiagnostic(checkJSDocFunctionTypeImplicitAny); + checkSignatureDeclaration(node); + + function checkJSDocFunctionTypeImplicitAny() { + if (!node.type && !isJSDocConstructSignature(node)) { + reportImplicitAny(node, anyType); + } + } + } + + function checkJSDocThisTag(node: JSDocThisTag) { + const host = getEffectiveJSDocHost(node); + if (host && isArrowFunction(host)) { + error(node.tagName, Diagnostics.An_arrow_function_cannot_have_a_this_parameter); + } + } + + function checkJSDocImportTag(node: JSDocImportTag) { + checkImportAttributes(node); + } + + function checkJSDocImplementsTag(node: JSDocImplementsTag): void { + const classLike = getEffectiveJSDocHost(node); + if (!classLike || !isClassDeclaration(classLike) && !isClassExpression(classLike)) { + error(classLike, Diagnostics.JSDoc_0_is_not_attached_to_a_class, idText(node.tagName)); + } + } + + function checkJSDocAugmentsTag(node: JSDocAugmentsTag): void { + const classLike = getEffectiveJSDocHost(node); + if (!classLike || !isClassDeclaration(classLike) && !isClassExpression(classLike)) { + error(classLike, Diagnostics.JSDoc_0_is_not_attached_to_a_class, idText(node.tagName)); + return; + } + + const augmentsTags = getJSDocTags(classLike).filter(isJSDocAugmentsTag); + Debug.assert(augmentsTags.length > 0); + if (augmentsTags.length > 1) { + error(augmentsTags[1], Diagnostics.Class_declarations_cannot_have_more_than_one_augments_or_extends_tag); + } + + const name = getIdentifierFromEntityNameExpression(node.class.expression); + const extend = getClassExtendsHeritageElement(classLike); + if (extend) { + const className = getIdentifierFromEntityNameExpression(extend.expression); + if (className && name.escapedText !== className.escapedText) { + error(name, Diagnostics.JSDoc_0_1_does_not_match_the_extends_2_clause, idText(node.tagName), idText(name), idText(className)); + } + } + } + + function checkJSDocAccessibilityModifiers(node: JSDocPublicTag | JSDocProtectedTag | JSDocPrivateTag): void { + const host = getJSDocHost(node); + if (host && isPrivateIdentifierClassElementDeclaration(host)) { + error(node, Diagnostics.An_accessibility_modifier_cannot_be_used_with_a_private_identifier); + } + } + + function getIdentifierFromEntityNameExpression(node: Identifier | PropertyAccessExpression): Identifier | PrivateIdentifier; + function getIdentifierFromEntityNameExpression(node: Expression): Identifier | PrivateIdentifier | undefined; + function getIdentifierFromEntityNameExpression(node: Expression): Identifier | PrivateIdentifier | undefined { + switch (node.kind) { + case SyntaxKind.Identifier: + return node as Identifier; + case SyntaxKind.PropertyAccessExpression: + return (node as PropertyAccessExpression).name; + default: + return undefined; + } + } + + function checkFunctionOrMethodDeclaration(node: FunctionDeclaration | MethodDeclaration | MethodSignature): void { + checkDecorators(node); + checkSignatureDeclaration(node); + const functionFlags = getFunctionFlags(node); + + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name && node.name.kind === SyntaxKind.ComputedPropertyName) { + // This check will account for methods in class/interface declarations, + // as well as accessors in classes/object literals + checkComputedPropertyName(node.name); + } + + if (hasBindableName(node)) { + // first we want to check the local symbol that contain this declaration + // - if node.localSymbol !== undefined - this is current declaration is exported and localSymbol points to the local symbol + // - if node.localSymbol === undefined - this node is non-exported so we can just pick the result of getSymbolOfNode + const symbol = getSymbolOfDeclaration(node); + const localSymbol = node.localSymbol || symbol; + + // Since the javascript won't do semantic analysis like typescript, + // if the javascript file comes before the typescript file and both contain same name functions, + // checkFunctionOrConstructorSymbol wouldn't be called if we didnt ignore javascript function. + const firstDeclaration = localSymbol.declarations?.find( + // Get first non javascript function declaration + declaration => declaration.kind === node.kind && !(declaration.flags & NodeFlags.JavaScriptFile), + ); + + // Only type check the symbol once + if (node === firstDeclaration) { + checkFunctionOrConstructorSymbol(localSymbol); + } + + if (symbol.parent) { + // run check on export symbol to check that modifiers agree across all exported declarations + checkFunctionOrConstructorSymbol(symbol); + } + } + + const body = node.kind === SyntaxKind.MethodSignature ? undefined : node.body; + checkSourceElement(body); + checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, getReturnTypeFromAnnotation(node)); + + addLazyDiagnostic(checkFunctionOrMethodDeclarationDiagnostics); + + // A js function declaration can have a @type tag instead of a return type node, but that type must have a call signature + if (isInJSFile(node)) { + const typeTag = getJSDocTypeTag(node); + if (typeTag && typeTag.typeExpression && !getContextualCallSignature(getTypeFromTypeNode(typeTag.typeExpression), node)) { + error(typeTag.typeExpression.type, Diagnostics.The_type_of_a_function_declaration_must_match_the_function_s_signature); + } + } + + function checkFunctionOrMethodDeclarationDiagnostics() { + if (!getEffectiveReturnTypeNode(node)) { + // Report an implicit any error if there is no body, no explicit return type, and node is not a private method + // in an ambient context + if (nodeIsMissing(body) && !isPrivateWithinAmbient(node)) { + reportImplicitAny(node, anyType); + } + + if (functionFlags & FunctionFlags.Generator && nodeIsPresent(body)) { + // A generator with a body and no type annotation can still cause errors. It can error if the + // yielded values have no common supertype, or it can give an implicit any error if it has no + // yielded values. The only way to trigger these errors is to try checking its return type. + getReturnTypeOfSignature(getSignatureFromDeclaration(node)); + } + } + } + } + + function registerForUnusedIdentifiersCheck(node: PotentiallyUnusedIdentifier): void { + addLazyDiagnostic(registerForUnusedIdentifiersCheckDiagnostics); + + function registerForUnusedIdentifiersCheckDiagnostics() { + // May be in a call such as getTypeOfNode that happened to call this. But potentiallyUnusedIdentifiers is only defined in the scope of `checkSourceFile`. + const sourceFile = getSourceFileOfNode(node); + let potentiallyUnusedIdentifiers = allPotentiallyUnusedIdentifiers.get(sourceFile.path); + if (!potentiallyUnusedIdentifiers) { + potentiallyUnusedIdentifiers = []; + allPotentiallyUnusedIdentifiers.set(sourceFile.path, potentiallyUnusedIdentifiers); + } + // TODO: GH#22580 + // Debug.assert(addToSeen(seenPotentiallyUnusedIdentifiers, getNodeId(node)), "Adding potentially-unused identifier twice"); + potentiallyUnusedIdentifiers.push(node); + } + } + + type PotentiallyUnusedIdentifier = SourceFile | ModuleDeclaration | ClassLikeDeclaration | InterfaceDeclaration | Block | CaseBlock | ForStatement | ForInStatement | ForOfStatement | Exclude | TypeAliasDeclaration | InferTypeNode; + + function checkUnusedIdentifiers(potentiallyUnusedIdentifiers: readonly PotentiallyUnusedIdentifier[], addDiagnostic: AddUnusedDiagnostic) { + for (const node of potentiallyUnusedIdentifiers) { + switch (node.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + checkUnusedClassMembers(node, addDiagnostic); + checkUnusedTypeParameters(node, addDiagnostic); + break; + case SyntaxKind.SourceFile: + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.Block: + case SyntaxKind.CaseBlock: + case SyntaxKind.ForStatement: + case SyntaxKind.ForInStatement: + case SyntaxKind.ForOfStatement: + checkUnusedLocalsAndParameters(node, addDiagnostic); + break; + case SyntaxKind.Constructor: + case SyntaxKind.FunctionExpression: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + if (node.body) { // Don't report unused parameters in overloads + checkUnusedLocalsAndParameters(node, addDiagnostic); + } + checkUnusedTypeParameters(node, addDiagnostic); + break; + case SyntaxKind.MethodSignature: + case SyntaxKind.CallSignature: + case SyntaxKind.ConstructSignature: + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.InterfaceDeclaration: + checkUnusedTypeParameters(node, addDiagnostic); + break; + case SyntaxKind.InferType: + checkUnusedInferTypeParameter(node, addDiagnostic); + break; + default: + Debug.assertNever(node, "Node should not have been registered for unused identifiers check"); + } + } + } + + function errorUnusedLocal(declaration: Declaration, name: string, addDiagnostic: AddUnusedDiagnostic) { + const node = getNameOfDeclaration(declaration) || declaration; + const message = isTypeDeclaration(declaration) ? Diagnostics._0_is_declared_but_never_used : Diagnostics._0_is_declared_but_its_value_is_never_read; + addDiagnostic(declaration, UnusedKind.Local, createDiagnosticForNode(node, message, name)); + } + + function isIdentifierThatStartsWithUnderscore(node: Node) { + return isIdentifier(node) && idText(node).charCodeAt(0) === CharacterCodes._; + } + + function checkUnusedClassMembers(node: ClassDeclaration | ClassExpression, addDiagnostic: AddUnusedDiagnostic): void { + for (const member of node.members) { + switch (member.kind) { + case SyntaxKind.MethodDeclaration: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + if (member.kind === SyntaxKind.SetAccessor && member.symbol.flags & SymbolFlags.GetAccessor) { + // Already would have reported an error on the getter. + break; + } + const symbol = getSymbolOfDeclaration(member); + if ( + !symbol.isReferenced + && (hasEffectiveModifier(member, ModifierFlags.Private) || isNamedDeclaration(member) && isPrivateIdentifier(member.name)) + && !(member.flags & NodeFlags.Ambient) + ) { + addDiagnostic(member, UnusedKind.Local, createDiagnosticForNode(member.name!, Diagnostics._0_is_declared_but_its_value_is_never_read, symbolToString(symbol))); + } + break; + case SyntaxKind.Constructor: + for (const parameter of (member as ConstructorDeclaration).parameters) { + if (!parameter.symbol.isReferenced && hasSyntacticModifier(parameter, ModifierFlags.Private)) { + addDiagnostic(parameter, UnusedKind.Local, createDiagnosticForNode(parameter.name, Diagnostics.Property_0_is_declared_but_its_value_is_never_read, symbolName(parameter.symbol))); + } + } + break; + case SyntaxKind.IndexSignature: + case SyntaxKind.SemicolonClassElement: + case SyntaxKind.ClassStaticBlockDeclaration: + // Can't be private + break; + default: + Debug.fail("Unexpected class member"); + } + } + } + + function checkUnusedInferTypeParameter(node: InferTypeNode, addDiagnostic: AddUnusedDiagnostic): void { + const { typeParameter } = node; + if (isTypeParameterUnused(typeParameter)) { + addDiagnostic(node, UnusedKind.Parameter, createDiagnosticForNode(node, Diagnostics._0_is_declared_but_its_value_is_never_read, idText(typeParameter.name))); + } + } + + function checkUnusedTypeParameters(node: ClassLikeDeclaration | SignatureDeclaration | InterfaceDeclaration | TypeAliasDeclaration, addDiagnostic: AddUnusedDiagnostic): void { + // Only report errors on the last declaration for the type parameter container; + // this ensures that all uses have been accounted for. + const declarations = getSymbolOfDeclaration(node).declarations; + if (!declarations || last(declarations) !== node) return; + + const typeParameters = getEffectiveTypeParameterDeclarations(node); + const seenParentsWithEveryUnused = new Set(); + + for (const typeParameter of typeParameters) { + if (!isTypeParameterUnused(typeParameter)) continue; + + const name = idText(typeParameter.name); + const { parent } = typeParameter; + if (parent.kind !== SyntaxKind.InferType && parent.typeParameters!.every(isTypeParameterUnused)) { + if (tryAddToSet(seenParentsWithEveryUnused, parent)) { + const sourceFile = getSourceFileOfNode(parent); + const range = isJSDocTemplateTag(parent) + // Whole @template tag + ? rangeOfNode(parent) + // Include the `<>` in the error message + : rangeOfTypeParameters(sourceFile, parent.typeParameters!); + const only = parent.typeParameters!.length === 1; + // TODO: following line is possible reason for bug #41974, unusedTypeParameters_TemplateTag + const messageAndArg: DiagnosticAndArguments = only + ? [Diagnostics._0_is_declared_but_its_value_is_never_read, name] + : [Diagnostics.All_type_parameters_are_unused]; + addDiagnostic(typeParameter, UnusedKind.Parameter, createFileDiagnostic(sourceFile, range.pos, range.end - range.pos, ...messageAndArg)); + } + } + else { + // TODO: following line is possible reason for bug #41974, unusedTypeParameters_TemplateTag + addDiagnostic(typeParameter, UnusedKind.Parameter, createDiagnosticForNode(typeParameter, Diagnostics._0_is_declared_but_its_value_is_never_read, name)); + } + } + } + function isTypeParameterUnused(typeParameter: TypeParameterDeclaration): boolean { + return !(getMergedSymbol(typeParameter.symbol).isReferenced! & SymbolFlags.TypeParameter) && !isIdentifierThatStartsWithUnderscore(typeParameter.name); + } + + function addToGroup(map: Map, key: K, value: V, getKey: (key: K) => number | string): void { + const keyString = String(getKey(key)); + const group = map.get(keyString); + if (group) { + group[1].push(value); + } + else { + map.set(keyString, [key, [value]]); + } + } + + function tryGetRootParameterDeclaration(node: Node): ParameterDeclaration | undefined { + return tryCast(getRootDeclaration(node), isParameter); + } + + function isValidUnusedLocalDeclaration(declaration: Declaration): boolean { + if (isBindingElement(declaration)) { + if (isObjectBindingPattern(declaration.parent)) { + /** + * ignore starts with underscore names _ + * const { a: _a } = { a: 1 } + */ + return !!(declaration.propertyName && isIdentifierThatStartsWithUnderscore(declaration.name)); + } + return isIdentifierThatStartsWithUnderscore(declaration.name); + } + return isAmbientModule(declaration) || + (isVariableDeclaration(declaration) && isForInOrOfStatement(declaration.parent.parent) || isImportedDeclaration(declaration)) && isIdentifierThatStartsWithUnderscore(declaration.name!); + } + + function checkUnusedLocalsAndParameters(nodeWithLocals: HasLocals, addDiagnostic: AddUnusedDiagnostic): void { + // Ideally we could use the ImportClause directly as a key, but must wait until we have full ES6 maps. So must store key along with value. + const unusedImports = new Map(); + const unusedDestructures = new Map(); + const unusedVariables = new Map(); + nodeWithLocals.locals!.forEach(local => { + // If it's purely a type parameter, ignore, will be checked in `checkUnusedTypeParameters`. + // If it's a type parameter merged with a parameter, check if the parameter-side is used. + if (local.flags & SymbolFlags.TypeParameter ? !(local.flags & SymbolFlags.Variable && !(local.isReferenced! & SymbolFlags.Variable)) : local.isReferenced || local.exportSymbol) { + return; + } + + if (local.declarations) { + for (const declaration of local.declarations) { + if (isValidUnusedLocalDeclaration(declaration)) { + continue; + } + + if (isImportedDeclaration(declaration)) { + addToGroup(unusedImports, importClauseFromImported(declaration), declaration, getNodeId); + } + else if (isBindingElement(declaration) && isObjectBindingPattern(declaration.parent)) { + // In `{ a, ...b }, `a` is considered used since it removes a property from `b`. `b` may still be unused though. + const lastElement = last(declaration.parent.elements); + if (declaration === lastElement || !last(declaration.parent.elements).dotDotDotToken) { + addToGroup(unusedDestructures, declaration.parent, declaration, getNodeId); + } + } + else if (isVariableDeclaration(declaration)) { + const blockScopeKind = getCombinedNodeFlagsCached(declaration) & NodeFlags.BlockScoped; + const name = getNameOfDeclaration(declaration); + if (blockScopeKind !== NodeFlags.Using && blockScopeKind !== NodeFlags.AwaitUsing || !name || !isIdentifierThatStartsWithUnderscore(name)) { + addToGroup(unusedVariables, declaration.parent, declaration, getNodeId); + } + } + else { + const parameter = local.valueDeclaration && tryGetRootParameterDeclaration(local.valueDeclaration); + const name = local.valueDeclaration && getNameOfDeclaration(local.valueDeclaration); + if (parameter && name) { + if (!isParameterPropertyDeclaration(parameter, parameter.parent) && !parameterIsThisKeyword(parameter) && !isIdentifierThatStartsWithUnderscore(name)) { + if (isBindingElement(declaration) && isArrayBindingPattern(declaration.parent)) { + addToGroup(unusedDestructures, declaration.parent, declaration, getNodeId); + } + else { + addDiagnostic(parameter, UnusedKind.Parameter, createDiagnosticForNode(name, Diagnostics._0_is_declared_but_its_value_is_never_read, symbolName(local))); + } + } + } + else { + errorUnusedLocal(declaration, symbolName(local), addDiagnostic); + } + } + } + } + }); + unusedImports.forEach(([importClause, unuseds]) => { + const importDecl = importClause.parent; + const nDeclarations = (importClause.name ? 1 : 0) + + (importClause.namedBindings ? + (importClause.namedBindings.kind === SyntaxKind.NamespaceImport ? 1 : importClause.namedBindings.elements.length) + : 0); + if (nDeclarations === unuseds.length) { + addDiagnostic( + importDecl, + UnusedKind.Local, + unuseds.length === 1 + ? createDiagnosticForNode(importDecl, Diagnostics._0_is_declared_but_its_value_is_never_read, idText(first(unuseds).name!)) + : createDiagnosticForNode(importDecl, Diagnostics.All_imports_in_import_declaration_are_unused), + ); + } + else { + for (const unused of unuseds) errorUnusedLocal(unused, idText(unused.name!), addDiagnostic); + } + }); + unusedDestructures.forEach(([bindingPattern, bindingElements]) => { + const kind = tryGetRootParameterDeclaration(bindingPattern.parent) ? UnusedKind.Parameter : UnusedKind.Local; + if (bindingPattern.elements.length === bindingElements.length) { + if (bindingElements.length === 1 && bindingPattern.parent.kind === SyntaxKind.VariableDeclaration && bindingPattern.parent.parent.kind === SyntaxKind.VariableDeclarationList) { + addToGroup(unusedVariables, bindingPattern.parent.parent, bindingPattern.parent, getNodeId); + } + else { + addDiagnostic( + bindingPattern, + kind, + bindingElements.length === 1 + ? createDiagnosticForNode(bindingPattern, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(first(bindingElements).name)) + : createDiagnosticForNode(bindingPattern, Diagnostics.All_destructured_elements_are_unused), + ); + } + } + else { + for (const e of bindingElements) { + addDiagnostic(e, kind, createDiagnosticForNode(e, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(e.name))); + } + } + }); + unusedVariables.forEach(([declarationList, declarations]) => { + if (declarationList.declarations.length === declarations.length) { + addDiagnostic( + declarationList, + UnusedKind.Local, + declarations.length === 1 + ? createDiagnosticForNode(first(declarations).name, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(first(declarations).name)) + : createDiagnosticForNode(declarationList.parent.kind === SyntaxKind.VariableStatement ? declarationList.parent : declarationList, Diagnostics.All_variables_are_unused), + ); + } + else { + for (const decl of declarations) { + addDiagnostic(decl, UnusedKind.Local, createDiagnosticForNode(decl, Diagnostics._0_is_declared_but_its_value_is_never_read, bindingNameText(decl.name))); + } + } + }); + } + + function checkPotentialUncheckedRenamedBindingElementsInTypes() { + for (const node of potentialUnusedRenamedBindingElementsInTypes) { + if (!getSymbolOfDeclaration(node)?.isReferenced) { + const wrappingDeclaration = walkUpBindingElementsAndPatterns(node); + Debug.assert(isPartOfParameterDeclaration(wrappingDeclaration), "Only parameter declaration should be checked here"); + const diagnostic = createDiagnosticForNode(node.name, Diagnostics._0_is_an_unused_renaming_of_1_Did_you_intend_to_use_it_as_a_type_annotation, declarationNameToString(node.name), declarationNameToString(node.propertyName)); + if (!wrappingDeclaration.type) { + // entire parameter does not have type annotation, suggest adding an annotation + addRelatedInfo( + diagnostic, + createFileDiagnostic(getSourceFileOfNode(wrappingDeclaration), wrappingDeclaration.end, 1, Diagnostics.We_can_only_write_a_type_for_0_by_adding_a_type_for_the_entire_parameter_here, declarationNameToString(node.propertyName)), + ); + } + diagnostics.add(diagnostic); + } + } + } + + function bindingNameText(name: BindingName): string { + switch (name.kind) { + case SyntaxKind.Identifier: + return idText(name); + case SyntaxKind.ArrayBindingPattern: + case SyntaxKind.ObjectBindingPattern: + return bindingNameText(cast(first(name.elements), isBindingElement).name); + default: + return Debug.assertNever(name); + } + } + + type ImportedDeclaration = ImportClause | ImportSpecifier | NamespaceImport; + function isImportedDeclaration(node: Node): node is ImportedDeclaration { + return node.kind === SyntaxKind.ImportClause || node.kind === SyntaxKind.ImportSpecifier || node.kind === SyntaxKind.NamespaceImport; + } + function importClauseFromImported(decl: ImportedDeclaration): ImportClause { + return decl.kind === SyntaxKind.ImportClause ? decl : decl.kind === SyntaxKind.NamespaceImport ? decl.parent : decl.parent.parent; + } + + function checkBlock(node: Block) { + // Grammar checking for SyntaxKind.Block + if (node.kind === SyntaxKind.Block) { + checkGrammarStatementInAmbientContext(node); + } + if (isFunctionOrModuleBlock(node)) { + const saveFlowAnalysisDisabled = flowAnalysisDisabled; + forEach(node.statements, checkSourceElement); + flowAnalysisDisabled = saveFlowAnalysisDisabled; + } + else { + forEach(node.statements, checkSourceElement); + } + if (node.locals) { + registerForUnusedIdentifiersCheck(node); + } + } + + function checkCollisionWithArgumentsInGeneratedCode(node: SignatureDeclaration) { + // no rest parameters \ declaration context \ overload - no codegen impact + if (languageVersion >= ScriptTarget.ES2015 || !hasRestParameter(node) || node.flags & NodeFlags.Ambient || nodeIsMissing((node as FunctionLikeDeclaration).body)) { + return; + } + + forEach(node.parameters, p => { + if (p.name && !isBindingPattern(p.name) && p.name.escapedText === argumentsSymbol.escapedName) { + errorSkippedOn("noEmit", p, Diagnostics.Duplicate_identifier_arguments_Compiler_uses_arguments_to_initialize_rest_parameters); + } + }); + } + + /** + * Checks whether an {@link Identifier}, in the context of another {@link Node}, would collide with a runtime value + * of {@link name} in an outer scope. This is used to check for collisions for downlevel transformations that + * require names like `Object`, `Promise`, `Reflect`, `require`, `exports`, etc. + */ + function needCollisionCheckForIdentifier(node: Node, identifier: Identifier | undefined, name: string): boolean { + if (identifier?.escapedText !== name) { + return false; + } + + if ( + node.kind === SyntaxKind.PropertyDeclaration || + node.kind === SyntaxKind.PropertySignature || + node.kind === SyntaxKind.MethodDeclaration || + node.kind === SyntaxKind.MethodSignature || + node.kind === SyntaxKind.GetAccessor || + node.kind === SyntaxKind.SetAccessor || + node.kind === SyntaxKind.PropertyAssignment + ) { + // it is ok to have member named '_super', '_this', `Promise`, etc. - member access is always qualified + return false; + } + + if (node.flags & NodeFlags.Ambient) { + // ambient context - no codegen impact + return false; + } + + if (isImportClause(node) || isImportEqualsDeclaration(node) || isImportSpecifier(node)) { + // type-only imports do not require collision checks against runtime values. + if (isTypeOnlyImportOrExportDeclaration(node)) { + return false; + } + } + + const root = getRootDeclaration(node); + if (isParameter(root) && nodeIsMissing((root.parent as FunctionLikeDeclaration).body)) { + // just an overload - no codegen impact + return false; + } + + return true; + } + + // this function will run after checking the source file so 'CaptureThis' is correct for all nodes + function checkIfThisIsCapturedInEnclosingScope(node: Node): void { + findAncestor(node, current => { + if (getNodeCheckFlags(current) & NodeCheckFlags.CaptureThis) { + const isDeclaration = node.kind !== SyntaxKind.Identifier; + if (isDeclaration) { + error(getNameOfDeclaration(node as Declaration), Diagnostics.Duplicate_identifier_this_Compiler_uses_variable_declaration_this_to_capture_this_reference); + } + else { + error(node, Diagnostics.Expression_resolves_to_variable_declaration_this_that_compiler_uses_to_capture_this_reference); + } + return true; + } + return false; + }); + } + + function checkIfNewTargetIsCapturedInEnclosingScope(node: Node): void { + findAncestor(node, current => { + if (getNodeCheckFlags(current) & NodeCheckFlags.CaptureNewTarget) { + const isDeclaration = node.kind !== SyntaxKind.Identifier; + if (isDeclaration) { + error(getNameOfDeclaration(node as Declaration), Diagnostics.Duplicate_identifier_newTarget_Compiler_uses_variable_declaration_newTarget_to_capture_new_target_meta_property_reference); + } + else { + error(node, Diagnostics.Expression_resolves_to_variable_declaration_newTarget_that_compiler_uses_to_capture_new_target_meta_property_reference); + } + return true; + } + return false; + }); + } + + function checkCollisionWithRequireExportsInGeneratedCode(node: Node, name: Identifier | undefined) { + // No need to check for require or exports for ES6 modules and later + if (moduleKind >= ModuleKind.ES2015 && !(moduleKind >= ModuleKind.Node16 && getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS)) { + return; + } + + if (!name || !needCollisionCheckForIdentifier(node, name, "require") && !needCollisionCheckForIdentifier(node, name, "exports")) { + return; + } + + // Uninstantiated modules shouldnt do this check + if (isModuleDeclaration(node) && getModuleInstanceState(node) !== ModuleInstanceState.Instantiated) { + return; + } + + // In case of variable declaration, node.parent is variable statement so look at the variable statement's parent + const parent = getDeclarationContainer(node); + if (parent.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(parent as SourceFile)) { + // If the declaration happens to be in external module, report error that require and exports are reserved keywords + errorSkippedOn("noEmit", name, Diagnostics.Duplicate_identifier_0_Compiler_reserves_name_1_in_top_level_scope_of_a_module, declarationNameToString(name), declarationNameToString(name)); + } + } + + function checkCollisionWithGlobalPromiseInGeneratedCode(node: Node, name: Identifier | undefined): void { + if (!name || languageVersion >= ScriptTarget.ES2017 || !needCollisionCheckForIdentifier(node, name, "Promise")) { + return; + } + + // Uninstantiated modules shouldnt do this check + if (isModuleDeclaration(node) && getModuleInstanceState(node) !== ModuleInstanceState.Instantiated) { + return; + } + + // In case of variable declaration, node.parent is variable statement so look at the variable statement's parent + const parent = getDeclarationContainer(node); + if (parent.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(parent as SourceFile) && parent.flags & NodeFlags.HasAsyncFunctions) { + // If the declaration happens to be in external module, report error that Promise is a reserved identifier. + errorSkippedOn("noEmit", name, Diagnostics.Duplicate_identifier_0_Compiler_reserves_name_1_in_top_level_scope_of_a_module_containing_async_functions, declarationNameToString(name), declarationNameToString(name)); + } + } + + function recordPotentialCollisionWithWeakMapSetInGeneratedCode(node: Node, name: Identifier): void { + if ( + languageVersion <= ScriptTarget.ES2021 + && (needCollisionCheckForIdentifier(node, name, "WeakMap") || needCollisionCheckForIdentifier(node, name, "WeakSet")) + ) { + potentialWeakMapSetCollisions.push(node); + } + } + + function checkWeakMapSetCollision(node: Node) { + const enclosingBlockScope = getEnclosingBlockScopeContainer(node); + if (getNodeCheckFlags(enclosingBlockScope) & NodeCheckFlags.ContainsClassWithPrivateIdentifiers) { + Debug.assert(isNamedDeclaration(node) && isIdentifier(node.name) && typeof node.name.escapedText === "string", "The target of a WeakMap/WeakSet collision check should be an identifier"); + errorSkippedOn("noEmit", node, Diagnostics.Compiler_reserves_name_0_when_emitting_private_identifier_downlevel, node.name.escapedText); + } + } + + function recordPotentialCollisionWithReflectInGeneratedCode(node: Node, name: Identifier | undefined): void { + if ( + name && languageVersion >= ScriptTarget.ES2015 && languageVersion <= ScriptTarget.ES2021 + && needCollisionCheckForIdentifier(node, name, "Reflect") + ) { + potentialReflectCollisions.push(node); + } + } + + function checkReflectCollision(node: Node) { + let hasCollision = false; + if (isClassExpression(node)) { + // ClassExpression names don't contribute to their containers, but do matter for any of their block-scoped members. + for (const member of node.members) { + if (getNodeCheckFlags(member) & NodeCheckFlags.ContainsSuperPropertyInStaticInitializer) { + hasCollision = true; + break; + } + } + } + else if (isFunctionExpression(node)) { + // FunctionExpression names don't contribute to their containers, but do matter for their contents + if (getNodeCheckFlags(node) & NodeCheckFlags.ContainsSuperPropertyInStaticInitializer) { + hasCollision = true; + } + } + else { + const container = getEnclosingBlockScopeContainer(node); + if (container && getNodeCheckFlags(container) & NodeCheckFlags.ContainsSuperPropertyInStaticInitializer) { + hasCollision = true; + } + } + if (hasCollision) { + Debug.assert(isNamedDeclaration(node) && isIdentifier(node.name), "The target of a Reflect collision check should be an identifier"); + errorSkippedOn("noEmit", node, Diagnostics.Duplicate_identifier_0_Compiler_reserves_name_1_when_emitting_super_references_in_static_initializers, declarationNameToString(node.name), "Reflect"); + } + } + + function checkCollisionsForDeclarationName(node: Node, name: Identifier | undefined) { + if (!name) return; + checkCollisionWithRequireExportsInGeneratedCode(node, name); + checkCollisionWithGlobalPromiseInGeneratedCode(node, name); + recordPotentialCollisionWithWeakMapSetInGeneratedCode(node, name); + recordPotentialCollisionWithReflectInGeneratedCode(node, name); + if (isClassLike(node)) { + checkTypeNameIsReserved(name, Diagnostics.Class_name_cannot_be_0); + if (!(node.flags & NodeFlags.Ambient)) { + checkClassNameCollisionWithObject(name); + } + } + else if (isEnumDeclaration(node)) { + checkTypeNameIsReserved(name, Diagnostics.Enum_name_cannot_be_0); + } + } + + function checkVarDeclaredNamesNotShadowed(node: VariableDeclaration | BindingElement) { + // - ScriptBody : StatementList + // It is a Syntax Error if any element of the LexicallyDeclaredNames of StatementList + // also occurs in the VarDeclaredNames of StatementList. + + // - Block : { StatementList } + // It is a Syntax Error if any element of the LexicallyDeclaredNames of StatementList + // also occurs in the VarDeclaredNames of StatementList. + + // Variable declarations are hoisted to the top of their function scope. They can shadow + // block scoped declarations, which bind tighter. this will not be flagged as duplicate definition + // by the binder as the declaration scope is different. + // A non-initialized declaration is a no-op as the block declaration will resolve before the var + // declaration. the problem is if the declaration has an initializer. this will act as a write to the + // block declared value. this is fine for let, but not const. + // Only consider declarations with initializers, uninitialized const declarations will not + // step on a let/const variable. + // Do not consider const and const declarations, as duplicate block-scoped declarations + // are handled by the binder. + // We are only looking for const declarations that step on let\const declarations from a + // different scope. e.g.: + // { + // const x = 0; // localDeclarationSymbol obtained after name resolution will correspond to this declaration + // const x = 0; // symbol for this declaration will be 'symbol' + // } + + // skip block-scoped variables and parameters + if ((getCombinedNodeFlagsCached(node) & NodeFlags.BlockScoped) !== 0 || isPartOfParameterDeclaration(node)) { + return; + } + + // NOTE: in ES6 spec initializer is required in variable declarations where name is binding pattern + // so we'll always treat binding elements as initialized + + const symbol = getSymbolOfDeclaration(node); + if (symbol.flags & SymbolFlags.FunctionScopedVariable) { + if (!isIdentifier(node.name)) return Debug.fail(); + const localDeclarationSymbol = resolveName(node, node.name.escapedText, SymbolFlags.Variable, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if ( + localDeclarationSymbol && + localDeclarationSymbol !== symbol && + localDeclarationSymbol.flags & SymbolFlags.BlockScopedVariable + ) { + if (getDeclarationNodeFlagsFromSymbol(localDeclarationSymbol) & NodeFlags.BlockScoped) { + const varDeclList = getAncestor(localDeclarationSymbol.valueDeclaration, SyntaxKind.VariableDeclarationList)!; + const container = varDeclList.parent.kind === SyntaxKind.VariableStatement && varDeclList.parent.parent + ? varDeclList.parent.parent + : undefined; + + // names of block-scoped and function scoped variables can collide only + // if block scoped variable is defined in the function\module\source file scope (because of variable hoisting) + const namesShareScope = container && + (container.kind === SyntaxKind.Block && isFunctionLike(container.parent) || + container.kind === SyntaxKind.ModuleBlock || + container.kind === SyntaxKind.ModuleDeclaration || + container.kind === SyntaxKind.SourceFile); + + // here we know that function scoped variable is "shadowed" by block scoped one + // a var declatation can't hoist past a lexical declaration and it results in a SyntaxError at runtime + if (!namesShareScope) { + const name = symbolToString(localDeclarationSymbol); + error(node, Diagnostics.Cannot_initialize_outer_scoped_variable_0_in_the_same_scope_as_block_scoped_declaration_1, name, name); + } + } + } + } + } + + function convertAutoToAny(type: Type) { + return type === autoType ? anyType : type === autoArrayType ? anyArrayType : type; + } + + // Check variable, parameter, or property declaration + function checkVariableLikeDeclaration(node: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement) { + checkDecorators(node); + if (!isBindingElement(node)) { + checkSourceElement(node.type); + } + + // JSDoc `function(string, string): string` syntax results in parameters with no name + if (!node.name) { + return; + } + + // For a computed property, just check the initializer and exit + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + if (hasOnlyExpressionInitializer(node) && node.initializer) { + checkExpressionCached(node.initializer); + } + } + + if (isBindingElement(node)) { + if ( + node.propertyName && + isIdentifier(node.name) && + isPartOfParameterDeclaration(node) && + nodeIsMissing((getContainingFunction(node) as FunctionLikeDeclaration).body) + ) { + // type F = ({a: string}) => void; + // ^^^^^^ + // variable renaming in function type notation is confusing, + // so we forbid it even if noUnusedLocals is not enabled + potentialUnusedRenamedBindingElementsInTypes.push(node); + return; + } + + if (isObjectBindingPattern(node.parent) && node.dotDotDotToken && languageVersion < LanguageFeatureMinimumTarget.ObjectSpreadRest) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Rest); + } + // check computed properties inside property names of binding elements + if (node.propertyName && node.propertyName.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.propertyName); + } + + // check private/protected variable access + const parent = node.parent.parent; + const parentCheckMode = node.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal; + const parentType = getTypeForBindingElementParent(parent, parentCheckMode); + const name = node.propertyName || node.name; + if (parentType && !isBindingPattern(name)) { + const exprType = getLiteralTypeFromPropertyName(name); + if (isTypeUsableAsPropertyName(exprType)) { + const nameText = getPropertyNameFromType(exprType); + const property = getPropertyOfType(parentType, nameText); + if (property) { + markPropertyAsReferenced(property, /*nodeForCheckWriteOnly*/ undefined, /*isSelfTypeAccess*/ false); // A destructuring is never a write-only reference. + checkPropertyAccessibility(node, !!parent.initializer && parent.initializer.kind === SyntaxKind.SuperKeyword, /*writing*/ false, parentType, property); + } + } + } + } + + // For a binding pattern, check contained binding elements + if (isBindingPattern(node.name)) { + if (node.name.kind === SyntaxKind.ArrayBindingPattern && languageVersion < LanguageFeatureMinimumTarget.BindingPatterns && compilerOptions.downlevelIteration) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Read); + } + + forEach(node.name.elements, checkSourceElement); + } + // For a parameter declaration with an initializer, error and exit if the containing function doesn't have a body + if (node.initializer && isPartOfParameterDeclaration(node) && nodeIsMissing((getContainingFunction(node) as FunctionLikeDeclaration).body)) { + error(node, Diagnostics.A_parameter_initializer_is_only_allowed_in_a_function_or_constructor_implementation); + return; + } + // For a binding pattern, validate the initializer and exit + if (isBindingPattern(node.name)) { + if (isInAmbientOrTypeNode(node)) { + return; + } + const needCheckInitializer = hasOnlyExpressionInitializer(node) && node.initializer && node.parent.parent.kind !== SyntaxKind.ForInStatement; + const needCheckWidenedType = !some(node.name.elements, not(isOmittedExpression)); + if (needCheckInitializer || needCheckWidenedType) { + // Don't validate for-in initializer as it is already an error + const widenedType = getWidenedTypeForVariableLikeDeclaration(node); + if (needCheckInitializer) { + const initializerType = checkExpressionCached(node.initializer); + if (strictNullChecks && needCheckWidenedType) { + checkNonNullNonVoidType(initializerType, node); + } + else { + checkTypeAssignableToAndOptionallyElaborate(initializerType, getWidenedTypeForVariableLikeDeclaration(node), node, node.initializer); + } + } + // check the binding pattern with empty elements + if (needCheckWidenedType) { + if (isArrayBindingPattern(node.name)) { + checkIteratedTypeOrElementType(IterationUse.Destructuring, widenedType, undefinedType, node); + } + else if (strictNullChecks) { + checkNonNullNonVoidType(widenedType, node); + } + } + } + return; + } + // For a commonjs `const x = require`, validate the alias and exit + const symbol = getSymbolOfDeclaration(node); + if (symbol.flags & SymbolFlags.Alias && (isVariableDeclarationInitializedToBareOrAccessedRequire(node) || isBindingElementOfBareOrAccessedRequire(node))) { + checkAliasSymbol(node); + return; + } + + const type = convertAutoToAny(getTypeOfSymbol(symbol)); + if (node === symbol.valueDeclaration) { + // Node is the primary declaration of the symbol, just validate the initializer + // Don't validate for-in initializer as it is already an error + const initializer = hasOnlyExpressionInitializer(node) && getEffectiveInitializer(node); + if (initializer) { + const isJSObjectLiteralInitializer = isInJSFile(node) && + isObjectLiteralExpression(initializer) && + (initializer.properties.length === 0 || isPrototypeAccess(node.name)) && + !!symbol.exports?.size; + if (!isJSObjectLiteralInitializer && node.parent.parent.kind !== SyntaxKind.ForInStatement) { + const initializerType = checkExpressionCached(initializer); + checkTypeAssignableToAndOptionallyElaborate(initializerType, type, node, initializer, /*headMessage*/ undefined); + const blockScopeKind = getCombinedNodeFlagsCached(node) & NodeFlags.BlockScoped; + if (blockScopeKind === NodeFlags.AwaitUsing) { + const globalAsyncDisposableType = getGlobalAsyncDisposableType(/*reportErrors*/ true); + const globalDisposableType = getGlobalDisposableType(/*reportErrors*/ true); + if (globalAsyncDisposableType !== emptyObjectType && globalDisposableType !== emptyObjectType) { + const optionalDisposableType = getUnionType([globalAsyncDisposableType, globalDisposableType, nullType, undefinedType]); + checkTypeAssignableTo(initializerType, optionalDisposableType, initializer, Diagnostics.The_initializer_of_an_await_using_declaration_must_be_either_an_object_with_a_Symbol_asyncDispose_or_Symbol_dispose_method_or_be_null_or_undefined); + } + } + else if (blockScopeKind === NodeFlags.Using) { + const globalDisposableType = getGlobalDisposableType(/*reportErrors*/ true); + if (globalDisposableType !== emptyObjectType) { + const optionalDisposableType = getUnionType([globalDisposableType, nullType, undefinedType]); + checkTypeAssignableTo(initializerType, optionalDisposableType, initializer, Diagnostics.The_initializer_of_a_using_declaration_must_be_either_an_object_with_a_Symbol_dispose_method_or_be_null_or_undefined); + } + } + } + } + if (symbol.declarations && symbol.declarations.length > 1) { + if (some(symbol.declarations, d => d !== node && isVariableLike(d) && !areDeclarationFlagsIdentical(d, node))) { + error(node.name, Diagnostics.All_declarations_of_0_must_have_identical_modifiers, declarationNameToString(node.name)); + } + } + } + else { + // Node is a secondary declaration, check that type is identical to primary declaration and check that + // initializer is consistent with type associated with the node + const declarationType = convertAutoToAny(getWidenedTypeForVariableLikeDeclaration(node)); + + if ( + !isErrorType(type) && !isErrorType(declarationType) && + !isTypeIdenticalTo(type, declarationType) && + !(symbol.flags & SymbolFlags.Assignment) + ) { + errorNextVariableOrPropertyDeclarationMustHaveSameType(symbol.valueDeclaration, type, node, declarationType); + } + if (hasOnlyExpressionInitializer(node) && node.initializer) { + checkTypeAssignableToAndOptionallyElaborate(checkExpressionCached(node.initializer), declarationType, node, node.initializer, /*headMessage*/ undefined); + } + if (symbol.valueDeclaration && !areDeclarationFlagsIdentical(node, symbol.valueDeclaration)) { + error(node.name, Diagnostics.All_declarations_of_0_must_have_identical_modifiers, declarationNameToString(node.name)); + } + } + if (node.kind !== SyntaxKind.PropertyDeclaration && node.kind !== SyntaxKind.PropertySignature) { + // We know we don't have a binding pattern or computed name here + checkExportsOnMergedDeclarations(node); + if (node.kind === SyntaxKind.VariableDeclaration || node.kind === SyntaxKind.BindingElement) { + checkVarDeclaredNamesNotShadowed(node); + } + checkCollisionsForDeclarationName(node, node.name); + } + } + + function errorNextVariableOrPropertyDeclarationMustHaveSameType(firstDeclaration: Declaration | undefined, firstType: Type, nextDeclaration: Declaration, nextType: Type): void { + const nextDeclarationName = getNameOfDeclaration(nextDeclaration); + const message = nextDeclaration.kind === SyntaxKind.PropertyDeclaration || nextDeclaration.kind === SyntaxKind.PropertySignature + ? Diagnostics.Subsequent_property_declarations_must_have_the_same_type_Property_0_must_be_of_type_1_but_here_has_type_2 + : Diagnostics.Subsequent_variable_declarations_must_have_the_same_type_Variable_0_must_be_of_type_1_but_here_has_type_2; + const declName = declarationNameToString(nextDeclarationName); + const err = error( + nextDeclarationName, + message, + declName, + typeToString(firstType), + typeToString(nextType), + ); + if (firstDeclaration) { + addRelatedInfo(err, createDiagnosticForNode(firstDeclaration, Diagnostics._0_was_also_declared_here, declName)); + } + } + + function areDeclarationFlagsIdentical(left: Declaration, right: Declaration) { + if ( + (left.kind === SyntaxKind.Parameter && right.kind === SyntaxKind.VariableDeclaration) || + (left.kind === SyntaxKind.VariableDeclaration && right.kind === SyntaxKind.Parameter) + ) { + // Differences in optionality between parameters and variables are allowed. + return true; + } + + if (hasQuestionToken(left) !== hasQuestionToken(right)) { + return false; + } + + const interestingFlags = ModifierFlags.Private | + ModifierFlags.Protected | + ModifierFlags.Async | + ModifierFlags.Abstract | + ModifierFlags.Readonly | + ModifierFlags.Static; + + return getSelectedEffectiveModifierFlags(left, interestingFlags) === getSelectedEffectiveModifierFlags(right, interestingFlags); + } + + function checkVariableDeclaration(node: VariableDeclaration) { + tracing?.push(tracing.Phase.Check, "checkVariableDeclaration", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); + checkGrammarVariableDeclaration(node); + checkVariableLikeDeclaration(node); + tracing?.pop(); + } + + function checkBindingElement(node: BindingElement) { + checkGrammarBindingElement(node); + return checkVariableLikeDeclaration(node); + } + + function checkVariableDeclarationList(node: VariableDeclarationList) { + const blockScopeKind = getCombinedNodeFlags(node) & NodeFlags.BlockScoped; + if ((blockScopeKind === NodeFlags.Using || blockScopeKind === NodeFlags.AwaitUsing) && languageVersion < LanguageFeatureMinimumTarget.UsingAndAwaitUsing) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.AddDisposableResourceAndDisposeResources); + } + + forEach(node.declarations, checkSourceElement); + } + + function checkVariableStatement(node: VariableStatement) { + // Grammar checking + if (!checkGrammarModifiers(node) && !checkGrammarVariableDeclarationList(node.declarationList)) checkGrammarForDisallowedBlockScopedVariableStatement(node); + checkVariableDeclarationList(node.declarationList); + } + + function checkExpressionStatement(node: ExpressionStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + checkExpression(node.expression); + } + + function checkIfStatement(node: IfStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + const type = checkTruthinessExpression(node.expression); + checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(node.expression, type, node.thenStatement); + checkSourceElement(node.thenStatement); + + if (node.thenStatement.kind === SyntaxKind.EmptyStatement) { + error(node.thenStatement, Diagnostics.The_body_of_an_if_statement_cannot_be_the_empty_statement); + } + + checkSourceElement(node.elseStatement); + } + + function checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(condExpr: Expression, condType: Type, body?: Statement | Expression) { + if (!strictNullChecks) return; + bothHelper(condExpr, body); + + function bothHelper(condExpr: Expression, body: Expression | Statement | undefined) { + condExpr = skipParentheses(condExpr); + + helper(condExpr, body); + + while (isBinaryExpression(condExpr) && (condExpr.operatorToken.kind === SyntaxKind.BarBarToken || condExpr.operatorToken.kind === SyntaxKind.QuestionQuestionToken)) { + condExpr = skipParentheses(condExpr.left); + helper(condExpr, body); + } + } + + function helper(condExpr: Expression, body: Expression | Statement | undefined) { + const location = isLogicalOrCoalescingBinaryExpression(condExpr) ? skipParentheses(condExpr.right) : condExpr; + if (isModuleExportsAccessExpression(location)) { + return; + } + if (isLogicalOrCoalescingBinaryExpression(location)) { + bothHelper(location, body); + return; + } + const type = location === condExpr ? condType : checkTruthinessExpression(location); + if (type.flags & TypeFlags.EnumLiteral && isPropertyAccessExpression(location) && (getNodeLinks(location.expression).resolvedSymbol ?? unknownSymbol).flags & SymbolFlags.Enum) { + // EnumLiteral type at condition with known value is always truthy or always falsy, likely an error + error(location, Diagnostics.This_condition_will_always_return_0, !!(type as LiteralType).value ? "true" : "false"); + return; + } + const isPropertyExpressionCast = isPropertyAccessExpression(location) && isTypeAssertion(location.expression); + if (!hasTypeFacts(type, TypeFacts.Truthy) || isPropertyExpressionCast) return; + + // While it technically should be invalid for any known-truthy value + // to be tested, we de-scope to functions and Promises unreferenced in + // the block as a heuristic to identify the most common bugs. There + // are too many false positives for values sourced from type + // definitions without strictNullChecks otherwise. + const callSignatures = getSignaturesOfType(type, SignatureKind.Call); + const isPromise = !!getAwaitedTypeOfPromise(type); + if (callSignatures.length === 0 && !isPromise) { + return; + } + + const testedNode = isIdentifier(location) ? location + : isPropertyAccessExpression(location) ? location.name + : undefined; + const testedSymbol = testedNode && getSymbolAtLocation(testedNode); + if (!testedSymbol && !isPromise) { + return; + } + + const isUsed = testedSymbol && isBinaryExpression(condExpr.parent) && isSymbolUsedInBinaryExpressionChain(condExpr.parent, testedSymbol) + || testedSymbol && body && isSymbolUsedInConditionBody(condExpr, body, testedNode, testedSymbol); + if (!isUsed) { + if (isPromise) { + errorAndMaybeSuggestAwait( + location, + /*maybeMissingAwait*/ true, + Diagnostics.This_condition_will_always_return_true_since_this_0_is_always_defined, + getTypeNameForErrorDisplay(type), + ); + } + else { + error(location, Diagnostics.This_condition_will_always_return_true_since_this_function_is_always_defined_Did_you_mean_to_call_it_instead); + } + } + } + } + + function isSymbolUsedInConditionBody(expr: Expression, body: Statement | Expression, testedNode: Node, testedSymbol: Symbol): boolean { + return !!forEachChild(body, function check(childNode): boolean | undefined { + if (isIdentifier(childNode)) { + const childSymbol = getSymbolAtLocation(childNode); + if (childSymbol && childSymbol === testedSymbol) { + // If the test was a simple identifier, the above check is sufficient + if (isIdentifier(expr) || isIdentifier(testedNode) && isBinaryExpression(testedNode.parent)) { + return true; + } + // Otherwise we need to ensure the symbol is called on the same target + let testedExpression = testedNode.parent; + let childExpression = childNode.parent; + while (testedExpression && childExpression) { + if ( + isIdentifier(testedExpression) && isIdentifier(childExpression) || + testedExpression.kind === SyntaxKind.ThisKeyword && childExpression.kind === SyntaxKind.ThisKeyword + ) { + return getSymbolAtLocation(testedExpression) === getSymbolAtLocation(childExpression); + } + else if (isPropertyAccessExpression(testedExpression) && isPropertyAccessExpression(childExpression)) { + if (getSymbolAtLocation(testedExpression.name) !== getSymbolAtLocation(childExpression.name)) { + return false; + } + childExpression = childExpression.expression; + testedExpression = testedExpression.expression; + } + else if (isCallExpression(testedExpression) && isCallExpression(childExpression)) { + childExpression = childExpression.expression; + testedExpression = testedExpression.expression; + } + else { + return false; + } + } + } + } + return forEachChild(childNode, check); + }); + } + + function isSymbolUsedInBinaryExpressionChain(node: Node, testedSymbol: Symbol): boolean { + while (isBinaryExpression(node) && node.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken) { + const isUsed = forEachChild(node.right, function visit(child): boolean | undefined { + if (isIdentifier(child)) { + const symbol = getSymbolAtLocation(child); + if (symbol && symbol === testedSymbol) { + return true; + } + } + return forEachChild(child, visit); + }); + if (isUsed) { + return true; + } + node = node.parent; + } + return false; + } + + function checkDoStatement(node: DoStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + checkSourceElement(node.statement); + checkTruthinessExpression(node.expression); + } + + function checkWhileStatement(node: WhileStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + checkTruthinessExpression(node.expression); + checkSourceElement(node.statement); + } + + function checkTruthinessOfType(type: Type, node: Node) { + if (type.flags & TypeFlags.Void) { + error(node, Diagnostics.An_expression_of_type_void_cannot_be_tested_for_truthiness); + } + return type; + } + + function checkTruthinessExpression(node: Expression, checkMode?: CheckMode) { + return checkTruthinessOfType(checkExpression(node, checkMode), node); + } + + function checkForStatement(node: ForStatement) { + // Grammar checking + if (!checkGrammarStatementInAmbientContext(node)) { + if (node.initializer && node.initializer.kind === SyntaxKind.VariableDeclarationList) { + checkGrammarVariableDeclarationList(node.initializer as VariableDeclarationList); + } + } + + if (node.initializer) { + if (node.initializer.kind === SyntaxKind.VariableDeclarationList) { + checkVariableDeclarationList(node.initializer as VariableDeclarationList); + } + else { + checkExpression(node.initializer); + } + } + + if (node.condition) checkTruthinessExpression(node.condition); + if (node.incrementor) checkExpression(node.incrementor); + checkSourceElement(node.statement); + if (node.locals) { + registerForUnusedIdentifiersCheck(node); + } + } + + function checkForOfStatement(node: ForOfStatement): void { + checkGrammarForInOrForOfStatement(node); + + const container = getContainingFunctionOrClassStaticBlock(node); + if (node.awaitModifier) { + if (container && isClassStaticBlockDeclaration(container)) { + grammarErrorOnNode(node.awaitModifier, Diagnostics.for_await_loops_cannot_be_used_inside_a_class_static_block); + } + else { + const functionFlags = getFunctionFlags(container); + if ((functionFlags & (FunctionFlags.Invalid | FunctionFlags.Async)) === FunctionFlags.Async && languageVersion < LanguageFeatureMinimumTarget.ForAwaitOf) { + // for..await..of in an async function or async generator function prior to ESNext requires the __asyncValues helper + checkExternalEmitHelpers(node, ExternalEmitHelpers.ForAwaitOfIncludes); + } + } + } + else if (compilerOptions.downlevelIteration && languageVersion < LanguageFeatureMinimumTarget.ForOf) { + // for..of prior to ES2015 requires the __values helper when downlevelIteration is enabled + checkExternalEmitHelpers(node, ExternalEmitHelpers.ForOfIncludes); + } + + // Check the LHS and RHS + // If the LHS is a declaration, just check it as a variable declaration, which will in turn check the RHS + // via checkRightHandSideOfForOf. + // If the LHS is an expression, check the LHS, as a destructuring assignment or as a reference. + // Then check that the RHS is assignable to it. + if (node.initializer.kind === SyntaxKind.VariableDeclarationList) { + checkVariableDeclarationList(node.initializer as VariableDeclarationList); + } + else { + const varExpr = node.initializer; + const iteratedType = checkRightHandSideOfForOf(node); + + // There may be a destructuring assignment on the left side + if (varExpr.kind === SyntaxKind.ArrayLiteralExpression || varExpr.kind === SyntaxKind.ObjectLiteralExpression) { + // iteratedType may be undefined. In this case, we still want to check the structure of + // varExpr, in particular making sure it's a valid LeftHandSideExpression. But we'd like + // to short circuit the type relation checking as much as possible, so we pass the unknownType. + checkDestructuringAssignment(varExpr, iteratedType || errorType); + } + else { + const leftType = checkExpression(varExpr); + checkReferenceExpression( + varExpr, + Diagnostics.The_left_hand_side_of_a_for_of_statement_must_be_a_variable_or_a_property_access, + Diagnostics.The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access, + ); + + // iteratedType will be undefined if the rightType was missing properties/signatures + // required to get its iteratedType (like [Symbol.iterator] or next). This may be + // because we accessed properties from anyType, or it may have led to an error inside + // getElementTypeOfIterable. + if (iteratedType) { + checkTypeAssignableToAndOptionallyElaborate(iteratedType, leftType, varExpr, node.expression); + } + } + } + + checkSourceElement(node.statement); + if (node.locals) { + registerForUnusedIdentifiersCheck(node); + } + } + + function checkForInStatement(node: ForInStatement) { + // Grammar checking + checkGrammarForInOrForOfStatement(node); + + const rightType = getNonNullableTypeIfNeeded(checkExpression(node.expression)); + // TypeScript 1.0 spec (April 2014): 5.4 + // In a 'for-in' statement of the form + // for (let VarDecl in Expr) Statement + // VarDecl must be a variable declaration without a type annotation that declares a variable of type Any, + // and Expr must be an expression of type Any, an object type, or a type parameter type. + if (node.initializer.kind === SyntaxKind.VariableDeclarationList) { + const variable = (node.initializer as VariableDeclarationList).declarations[0]; + if (variable && isBindingPattern(variable.name)) { + error(variable.name, Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_a_destructuring_pattern); + } + checkVariableDeclarationList(node.initializer as VariableDeclarationList); + } + else { + // In a 'for-in' statement of the form + // for (Var in Expr) Statement + // Var must be an expression classified as a reference of type Any or the String primitive type, + // and Expr must be an expression of type Any, an object type, or a type parameter type. + const varExpr = node.initializer; + const leftType = checkExpression(varExpr); + if (varExpr.kind === SyntaxKind.ArrayLiteralExpression || varExpr.kind === SyntaxKind.ObjectLiteralExpression) { + error(varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_a_destructuring_pattern); + } + else if (!isTypeAssignableTo(getIndexTypeOrString(rightType), leftType)) { + error(varExpr, Diagnostics.The_left_hand_side_of_a_for_in_statement_must_be_of_type_string_or_any); + } + else { + // run check only former check succeeded to avoid cascading errors + checkReferenceExpression( + varExpr, + Diagnostics.The_left_hand_side_of_a_for_in_statement_must_be_a_variable_or_a_property_access, + Diagnostics.The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access, + ); + } + } + + // unknownType is returned i.e. if node.expression is identifier whose name cannot be resolved + // in this case error about missing name is already reported - do not report extra one + if (rightType === neverType || !isTypeAssignableToKind(rightType, TypeFlags.NonPrimitive | TypeFlags.InstantiableNonPrimitive)) { + error(node.expression, Diagnostics.The_right_hand_side_of_a_for_in_statement_must_be_of_type_any_an_object_type_or_a_type_parameter_but_here_has_type_0, typeToString(rightType)); + } + + checkSourceElement(node.statement); + if (node.locals) { + registerForUnusedIdentifiersCheck(node); + } + } + + function checkRightHandSideOfForOf(statement: ForOfStatement): Type { + const use = statement.awaitModifier ? IterationUse.ForAwaitOf : IterationUse.ForOf; + return checkIteratedTypeOrElementType(use, checkNonNullExpression(statement.expression), undefinedType, statement.expression); + } + + function checkIteratedTypeOrElementType(use: IterationUse, inputType: Type, sentType: Type, errorNode: Node | undefined): Type { + if (isTypeAny(inputType)) { + return inputType; + } + return getIteratedTypeOrElementType(use, inputType, sentType, errorNode, /*checkAssignability*/ true) || anyType; + } + + /** + * When consuming an iterable type in a for..of, spread, or iterator destructuring assignment + * we want to get the iterated type of an iterable for ES2015 or later, or the iterated type + * of a iterable (if defined globally) or element type of an array like for ES2015 or earlier. + */ + function getIteratedTypeOrElementType(use: IterationUse, inputType: Type, sentType: Type, errorNode: Node | undefined, checkAssignability: boolean): Type | undefined { + const allowAsyncIterables = (use & IterationUse.AllowsAsyncIterablesFlag) !== 0; + if (inputType === neverType) { + if (errorNode) { + reportTypeNotIterableError(errorNode, inputType, allowAsyncIterables); + } + return undefined; + } + + const uplevelIteration = languageVersion >= ScriptTarget.ES2015; + const downlevelIteration = !uplevelIteration && compilerOptions.downlevelIteration; + const possibleOutOfBounds = compilerOptions.noUncheckedIndexedAccess && !!(use & IterationUse.PossiblyOutOfBounds); + + // Get the iterated type of an `Iterable` or `IterableIterator` only in ES2015 + // or higher, when inside of an async generator or for-await-if, or when + // downlevelIteration is requested. + if (uplevelIteration || downlevelIteration || allowAsyncIterables) { + // We only report errors for an invalid iterable type in ES2015 or higher. + const iterationTypes = getIterationTypesOfIterable(inputType, use, uplevelIteration ? errorNode : undefined); + if (checkAssignability) { + if (iterationTypes) { + const diagnostic = use & IterationUse.ForOfFlag ? Diagnostics.Cannot_iterate_value_because_the_next_method_of_its_iterator_expects_type_1_but_for_of_will_always_send_0 : + use & IterationUse.SpreadFlag ? Diagnostics.Cannot_iterate_value_because_the_next_method_of_its_iterator_expects_type_1_but_array_spread_will_always_send_0 : + use & IterationUse.DestructuringFlag ? Diagnostics.Cannot_iterate_value_because_the_next_method_of_its_iterator_expects_type_1_but_array_destructuring_will_always_send_0 : + use & IterationUse.YieldStarFlag ? Diagnostics.Cannot_delegate_iteration_to_value_because_the_next_method_of_its_iterator_expects_type_1_but_the_containing_generator_will_always_send_0 : + undefined; + if (diagnostic) { + checkTypeAssignableTo(sentType, iterationTypes.nextType, errorNode, diagnostic); + } + } + } + if (iterationTypes || uplevelIteration) { + return possibleOutOfBounds ? includeUndefinedInIndexSignature(iterationTypes && iterationTypes.yieldType) : (iterationTypes && iterationTypes.yieldType); + } + } + + let arrayType = inputType; + let hasStringConstituent = false; + + // If strings are permitted, remove any string-like constituents from the array type. + // This allows us to find other non-string element types from an array unioned with + // a string. + if (use & IterationUse.AllowsStringInputFlag) { + if (arrayType.flags & TypeFlags.Union) { + // After we remove all types that are StringLike, we will know if there was a string constituent + // based on whether the result of filter is a new array. + const arrayTypes = (inputType as UnionType).types; + const filteredTypes = filter(arrayTypes, t => !(t.flags & TypeFlags.StringLike)); + if (filteredTypes !== arrayTypes) { + arrayType = getUnionType(filteredTypes, UnionReduction.Subtype); + } + } + else if (arrayType.flags & TypeFlags.StringLike) { + arrayType = neverType; + } + + hasStringConstituent = arrayType !== inputType; + if (hasStringConstituent) { + // Now that we've removed all the StringLike types, if no constituents remain, then the entire + // arrayOrStringType was a string. + if (arrayType.flags & TypeFlags.Never) { + return possibleOutOfBounds ? includeUndefinedInIndexSignature(stringType) : stringType; + } + } + } + + if (!isArrayLikeType(arrayType)) { + if (errorNode) { + // Which error we report depends on whether we allow strings or if there was a + // string constituent. For example, if the input type is number | string, we + // want to say that number is not an array type. But if the input was just + // number and string input is allowed, we want to say that number is not an + // array type or a string type. + const allowsStrings = !!(use & IterationUse.AllowsStringInputFlag) && !hasStringConstituent; + const [defaultDiagnostic, maybeMissingAwait] = getIterationDiagnosticDetails(allowsStrings, downlevelIteration); + errorAndMaybeSuggestAwait( + errorNode, + maybeMissingAwait && !!getAwaitedTypeOfPromise(arrayType), + defaultDiagnostic, + typeToString(arrayType), + ); + } + return hasStringConstituent ? possibleOutOfBounds ? includeUndefinedInIndexSignature(stringType) : stringType : undefined; + } + + const arrayElementType = getIndexTypeOfType(arrayType, numberType); + if (hasStringConstituent && arrayElementType) { + // This is just an optimization for the case where arrayOrStringType is string | string[] + if (arrayElementType.flags & TypeFlags.StringLike && !compilerOptions.noUncheckedIndexedAccess) { + return stringType; + } + + return getUnionType(possibleOutOfBounds ? [arrayElementType, stringType, undefinedType] : [arrayElementType, stringType], UnionReduction.Subtype); + } + + return (use & IterationUse.PossiblyOutOfBounds) ? includeUndefinedInIndexSignature(arrayElementType) : arrayElementType; + + function getIterationDiagnosticDetails(allowsStrings: boolean, downlevelIteration: boolean | undefined): [error: DiagnosticMessage, maybeMissingAwait: boolean] { + if (downlevelIteration) { + return allowsStrings + ? [Diagnostics.Type_0_is_not_an_array_type_or_a_string_type_or_does_not_have_a_Symbol_iterator_method_that_returns_an_iterator, true] + : [Diagnostics.Type_0_is_not_an_array_type_or_does_not_have_a_Symbol_iterator_method_that_returns_an_iterator, true]; + } + + const yieldType = getIterationTypeOfIterable(use, IterationTypeKind.Yield, inputType, /*errorNode*/ undefined); + + if (yieldType) { + return [Diagnostics.Type_0_can_only_be_iterated_through_when_using_the_downlevelIteration_flag_or_with_a_target_of_es2015_or_higher, false]; + } + + if (isES2015OrLaterIterable(inputType.symbol?.escapedName)) { + return [Diagnostics.Type_0_can_only_be_iterated_through_when_using_the_downlevelIteration_flag_or_with_a_target_of_es2015_or_higher, true]; + } + + return allowsStrings + ? [Diagnostics.Type_0_is_not_an_array_type_or_a_string_type, true] + : [Diagnostics.Type_0_is_not_an_array_type, true]; + } + } + + function isES2015OrLaterIterable(n: __String) { + switch (n) { + case "Float32Array": + case "Float64Array": + case "Int16Array": + case "Int32Array": + case "Int8Array": + case "NodeList": + case "Uint16Array": + case "Uint32Array": + case "Uint8Array": + case "Uint8ClampedArray": + return true; + } + return false; + } + + /** + * Gets the requested "iteration type" from an `Iterable`-like or `AsyncIterable`-like type. + */ + function getIterationTypeOfIterable(use: IterationUse, typeKind: IterationTypeKind, inputType: Type, errorNode: Node | undefined): Type | undefined { + if (isTypeAny(inputType)) { + return undefined; + } + + const iterationTypes = getIterationTypesOfIterable(inputType, use, errorNode); + return iterationTypes && iterationTypes[getIterationTypesKeyFromIterationTypeKind(typeKind)]; + } + + function createIterationTypes(yieldType: Type = neverType, returnType: Type = neverType, nextType: Type = unknownType): IterationTypes { + // `yieldType` and `returnType` are defaulted to `neverType` they each will be combined + // via `getUnionType` when merging iteration types. `nextType` is defined as `unknownType` + // as it is combined via `getIntersectionType` when merging iteration types. + + // Use the cache only for intrinsic types to keep it small as they are likely to be + // more frequently created (i.e. `Iterator`). Iteration types + // are also cached on the type they are requested for, so we shouldn't need to maintain + // the cache for less-frequently used types. + if ( + yieldType.flags & TypeFlags.Intrinsic && + returnType.flags & (TypeFlags.Any | TypeFlags.Never | TypeFlags.Unknown | TypeFlags.Void | TypeFlags.Undefined) && + nextType.flags & (TypeFlags.Any | TypeFlags.Never | TypeFlags.Unknown | TypeFlags.Void | TypeFlags.Undefined) + ) { + const id = getTypeListId([yieldType, returnType, nextType]); + let iterationTypes = iterationTypesCache.get(id); + if (!iterationTypes) { + iterationTypes = { yieldType, returnType, nextType }; + iterationTypesCache.set(id, iterationTypes); + } + return iterationTypes; + } + return { yieldType, returnType, nextType }; + } + + /** + * Combines multiple `IterationTypes` records. + * + * If `array` is empty or all elements are missing or are references to `noIterationTypes`, + * then `noIterationTypes` is returned. Otherwise, an `IterationTypes` record is returned + * for the combined iteration types. + */ + function combineIterationTypes(array: (IterationTypes | undefined)[]) { + let yieldTypes: Type[] | undefined; + let returnTypes: Type[] | undefined; + let nextTypes: Type[] | undefined; + for (const iterationTypes of array) { + if (iterationTypes === undefined || iterationTypes === noIterationTypes) { + continue; + } + if (iterationTypes === anyIterationTypes) { + return anyIterationTypes; + } + yieldTypes = append(yieldTypes, iterationTypes.yieldType); + returnTypes = append(returnTypes, iterationTypes.returnType); + nextTypes = append(nextTypes, iterationTypes.nextType); + } + if (yieldTypes || returnTypes || nextTypes) { + return createIterationTypes( + yieldTypes && getUnionType(yieldTypes), + returnTypes && getUnionType(returnTypes), + nextTypes && getIntersectionType(nextTypes), + ); + } + return noIterationTypes; + } + + function getCachedIterationTypes(type: Type, cacheKey: MatchingKeys) { + return (type as IterableOrIteratorType)[cacheKey]; + } + + function setCachedIterationTypes(type: Type, cacheKey: MatchingKeys, cachedTypes: IterationTypes) { + return (type as IterableOrIteratorType)[cacheKey] = cachedTypes; + } + + /** + * Gets the *yield*, *return*, and *next* types from an `Iterable`-like or `AsyncIterable`-like type. + * + * At every level that involves analyzing return types of signatures, we union the return types of all the signatures. + * + * Another thing to note is that at any step of this process, we could run into a dead end, + * meaning either the property is missing, or we run into the anyType. If either of these things + * happens, we return `undefined` to signal that we could not find the iteration type. If a property + * is missing, and the previous step did not result in `any`, then we also give an error if the + * caller requested it. Then the caller can decide what to do in the case where there is no iterated + * type. + * + * For a **for-of** statement, `yield*` (in a normal generator), spread, array + * destructuring, or normal generator we will only ever look for a `[Symbol.iterator]()` + * method. + * + * For an async generator we will only ever look at the `[Symbol.asyncIterator]()` method. + * + * For a **for-await-of** statement or a `yield*` in an async generator we will look for + * the `[Symbol.asyncIterator]()` method first, and then the `[Symbol.iterator]()` method. + */ + function getIterationTypesOfIterable(type: Type, use: IterationUse, errorNode: Node | undefined) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + if (!(type.flags & TypeFlags.Union)) { + const errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined = errorNode ? { errors: undefined } : undefined; + const iterationTypes = getIterationTypesOfIterableWorker(type, use, errorNode, errorOutputContainer); + if (iterationTypes === noIterationTypes) { + if (errorNode) { + const rootDiag = reportTypeNotIterableError(errorNode, type, !!(use & IterationUse.AllowsAsyncIterablesFlag)); + if (errorOutputContainer?.errors) { + addRelatedInfo(rootDiag, ...errorOutputContainer.errors); + } + } + return undefined; + } + else if (errorOutputContainer?.errors?.length) { + for (const diag of errorOutputContainer.errors) { + diagnostics.add(diag); + } + } + return iterationTypes; + } + + const cacheKey = use & IterationUse.AllowsAsyncIterablesFlag ? "iterationTypesOfAsyncIterable" : "iterationTypesOfIterable"; + const cachedTypes = getCachedIterationTypes(type, cacheKey); + if (cachedTypes) return cachedTypes === noIterationTypes ? undefined : cachedTypes; + + let allIterationTypes: IterationTypes[] | undefined; + for (const constituent of (type as UnionType).types) { + const errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined = errorNode ? { errors: undefined } : undefined; + const iterationTypes = getIterationTypesOfIterableWorker(constituent, use, errorNode, errorOutputContainer); + if (iterationTypes === noIterationTypes) { + if (errorNode) { + const rootDiag = reportTypeNotIterableError(errorNode, type, !!(use & IterationUse.AllowsAsyncIterablesFlag)); + if (errorOutputContainer?.errors) { + addRelatedInfo(rootDiag, ...errorOutputContainer.errors); + } + } + setCachedIterationTypes(type, cacheKey, noIterationTypes); + return undefined; + } + else if (errorOutputContainer?.errors?.length) { + for (const diag of errorOutputContainer.errors) { + diagnostics.add(diag); + } + } + + allIterationTypes = append(allIterationTypes, iterationTypes); + } + + const iterationTypes = allIterationTypes ? combineIterationTypes(allIterationTypes) : noIterationTypes; + setCachedIterationTypes(type, cacheKey, iterationTypes); + return iterationTypes === noIterationTypes ? undefined : iterationTypes; + } + + function getAsyncFromSyncIterationTypes(iterationTypes: IterationTypes, errorNode: Node | undefined) { + if (iterationTypes === noIterationTypes) return noIterationTypes; + if (iterationTypes === anyIterationTypes) return anyIterationTypes; + const { yieldType, returnType, nextType } = iterationTypes; + // if we're requesting diagnostics, report errors for a missing `Awaited`. + if (errorNode) { + getGlobalAwaitedSymbol(/*reportErrors*/ true); + } + return createIterationTypes( + getAwaitedType(yieldType, errorNode) || anyType, + getAwaitedType(returnType, errorNode) || anyType, + nextType, + ); + } + + /** + * Gets the *yield*, *return*, and *next* types from a non-union type. + * + * If we are unable to find the *yield*, *return*, and *next* types, `noIterationTypes` is + * returned to indicate to the caller that it should report an error. Otherwise, an + * `IterationTypes` record is returned. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterable` instead. + */ + function getIterationTypesOfIterableWorker(type: Type, use: IterationUse, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + // If we are reporting errors and encounter a cached `noIterationTypes`, we should ignore the cached value and continue as if nothing was cached. + // In addition, we should not cache any new results for this call. + let noCache = false; + + if (use & IterationUse.AllowsAsyncIterablesFlag) { + const iterationTypes = getIterationTypesOfIterableCached(type, asyncIterationTypesResolver) || + getIterationTypesOfIterableFast(type, asyncIterationTypesResolver); + if (iterationTypes) { + if (iterationTypes === noIterationTypes && errorNode) { + // ignore the cached value + noCache = true; + } + else { + return use & IterationUse.ForOfFlag ? + getAsyncFromSyncIterationTypes(iterationTypes, errorNode) : + iterationTypes; + } + } + } + + if (use & IterationUse.AllowsSyncIterablesFlag) { + let iterationTypes = getIterationTypesOfIterableCached(type, syncIterationTypesResolver) || + getIterationTypesOfIterableFast(type, syncIterationTypesResolver); + if (iterationTypes) { + if (iterationTypes === noIterationTypes && errorNode) { + // ignore the cached value + noCache = true; + } + else { + if (use & IterationUse.AllowsAsyncIterablesFlag) { + // for a sync iterable in an async context, only use the cached types if they are valid. + if (iterationTypes !== noIterationTypes) { + iterationTypes = getAsyncFromSyncIterationTypes(iterationTypes, errorNode); + return noCache ? iterationTypes : setCachedIterationTypes(type, "iterationTypesOfAsyncIterable", iterationTypes); + } + } + else { + return iterationTypes; + } + } + } + } + + if (use & IterationUse.AllowsAsyncIterablesFlag) { + const iterationTypes = getIterationTypesOfIterableSlow(type, asyncIterationTypesResolver, errorNode, errorOutputContainer, noCache); + if (iterationTypes !== noIterationTypes) { + return iterationTypes; + } + } + + if (use & IterationUse.AllowsSyncIterablesFlag) { + let iterationTypes = getIterationTypesOfIterableSlow(type, syncIterationTypesResolver, errorNode, errorOutputContainer, noCache); + if (iterationTypes !== noIterationTypes) { + if (use & IterationUse.AllowsAsyncIterablesFlag) { + iterationTypes = getAsyncFromSyncIterationTypes(iterationTypes, errorNode); + return noCache ? iterationTypes : setCachedIterationTypes(type, "iterationTypesOfAsyncIterable", iterationTypes); + } + else { + return iterationTypes; + } + } + } + + return noIterationTypes; + } + + /** + * Gets the *yield*, *return*, and *next* types of an `Iterable`-like or + * `AsyncIterable`-like type from the cache. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterable` instead. + */ + function getIterationTypesOfIterableCached(type: Type, resolver: IterationTypesResolver) { + return getCachedIterationTypes(type, resolver.iterableCacheKey); + } + + function getIterationTypesOfGlobalIterableType(globalType: Type, resolver: IterationTypesResolver) { + const globalIterationTypes = getIterationTypesOfIterableCached(globalType, resolver) || + getIterationTypesOfIterableSlow(globalType, resolver, /*errorNode*/ undefined, /*errorOutputContainer*/ undefined, /*noCache*/ false); + return globalIterationTypes === noIterationTypes ? defaultIterationTypes : globalIterationTypes; + } + + /** + * Gets the *yield*, *return*, and *next* types of an `Iterable`-like or `AsyncIterable`-like + * type from from common heuristics. + * + * If we previously analyzed this type and found no iteration types, `noIterationTypes` is + * returned. If we found iteration types, an `IterationTypes` record is returned. + * Otherwise, we return `undefined` to indicate to the caller it should perform a more + * exhaustive analysis. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterable` instead. + */ + function getIterationTypesOfIterableFast(type: Type, resolver: IterationTypesResolver) { + // As an optimization, if the type is an instantiation of one of the following global types, then + // just grab its related type argument: + // - `Iterable` or `AsyncIterable` + // - `IterableIterator` or `AsyncIterableIterator` + let globalType: Type; + if ( + isReferenceToType(type, globalType = resolver.getGlobalIterableType(/*reportErrors*/ false)) || + isReferenceToType(type, globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false)) + ) { + const [yieldType] = getTypeArguments(type as GenericType); + // The "return" and "next" types of `Iterable` and `IterableIterator` are defined by the + // iteration types of their `[Symbol.iterator]()` method. The same is true for their async cousins. + // While we define these as `any` and `undefined` in our libs by default, a custom lib *could* use + // different definitions. + const { returnType, nextType } = getIterationTypesOfGlobalIterableType(globalType, resolver); + return setCachedIterationTypes(type, resolver.iterableCacheKey, createIterationTypes(resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || yieldType, resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || returnType, nextType)); + } + + // As an optimization, if the type is an instantiation of the following global type, then + // just grab its related type arguments: + // - `Generator` or `AsyncGenerator` + if (isReferenceToType(type, resolver.getGlobalGeneratorType(/*reportErrors*/ false))) { + const [yieldType, returnType, nextType] = getTypeArguments(type as GenericType); + return setCachedIterationTypes(type, resolver.iterableCacheKey, createIterationTypes(resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || yieldType, resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || returnType, nextType)); + } + } + + function getPropertyNameForKnownSymbolName(symbolName: string): __String { + const ctorType = getGlobalESSymbolConstructorSymbol(/*reportErrors*/ false); + const uniqueType = ctorType && getTypeOfPropertyOfType(getTypeOfSymbol(ctorType), escapeLeadingUnderscores(symbolName)); + return uniqueType && isTypeUsableAsPropertyName(uniqueType) ? getPropertyNameFromType(uniqueType) : `__@${symbolName}` as __String; + } + + /** + * Gets the *yield*, *return*, and *next* types of an `Iterable`-like or `AsyncIterable`-like + * type from its members. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, `noIterationTypes` is returned. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterable` instead. + */ + function getIterationTypesOfIterableSlow(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined, noCache: boolean) { + const method = getPropertyOfType(type, getPropertyNameForKnownSymbolName(resolver.iteratorSymbolName)); + const methodType = method && !(method.flags & SymbolFlags.Optional) ? getTypeOfSymbol(method) : undefined; + if (isTypeAny(methodType)) { + return noCache ? anyIterationTypes : setCachedIterationTypes(type, resolver.iterableCacheKey, anyIterationTypes); + } + + const signatures = methodType ? getSignaturesOfType(methodType, SignatureKind.Call) : undefined; + if (!some(signatures)) { + return noCache ? noIterationTypes : setCachedIterationTypes(type, resolver.iterableCacheKey, noIterationTypes); + } + + const iteratorType = getIntersectionType(map(signatures, getReturnTypeOfSignature)); + const iterationTypes = getIterationTypesOfIteratorWorker(iteratorType, resolver, errorNode, errorOutputContainer, noCache) ?? noIterationTypes; + return noCache ? iterationTypes : setCachedIterationTypes(type, resolver.iterableCacheKey, iterationTypes); + } + + function reportTypeNotIterableError(errorNode: Node, type: Type, allowAsyncIterables: boolean): Diagnostic { + const message = allowAsyncIterables + ? Diagnostics.Type_0_must_have_a_Symbol_asyncIterator_method_that_returns_an_async_iterator + : Diagnostics.Type_0_must_have_a_Symbol_iterator_method_that_returns_an_iterator; + const suggestAwait = + // for (const x of Promise<...>) or [...Promise<...>] + !!getAwaitedTypeOfPromise(type) + // for (const x of AsyncIterable<...>) + || ( + !allowAsyncIterables && + isForOfStatement(errorNode.parent) && + errorNode.parent.expression === errorNode && + getGlobalAsyncIterableType(/*reportErrors*/ false) !== emptyGenericType && + isTypeAssignableTo(type, getGlobalAsyncIterableType(/*reportErrors*/ false)) + ); + return errorAndMaybeSuggestAwait(errorNode, suggestAwait, message, typeToString(type)); + } + + /** + * Gets the *yield*, *return*, and *next* types from an `Iterator`-like or `AsyncIterator`-like type. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, `undefined` is returned. + */ + function getIterationTypesOfIterator(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined) { + return getIterationTypesOfIteratorWorker(type, resolver, errorNode, errorOutputContainer, /*noCache*/ false); + } + + /** + * Gets the *yield*, *return*, and *next* types from an `Iterator`-like or `AsyncIterator`-like type. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, `undefined` is returned. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterator` instead. + */ + function getIterationTypesOfIteratorWorker(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined, noCache: boolean) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + let iterationTypes = getIterationTypesOfIteratorCached(type, resolver) || + getIterationTypesOfIteratorFast(type, resolver); + + if (iterationTypes === noIterationTypes && errorNode) { + iterationTypes = undefined; + noCache = true; + } + + iterationTypes ??= getIterationTypesOfIteratorSlow(type, resolver, errorNode, errorOutputContainer, noCache); + return iterationTypes === noIterationTypes ? undefined : iterationTypes; + } + + /** + * Gets the iteration types of an `Iterator`-like or `AsyncIterator`-like type from the + * cache. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterator` instead. + */ + function getIterationTypesOfIteratorCached(type: Type, resolver: IterationTypesResolver) { + return getCachedIterationTypes(type, resolver.iteratorCacheKey); + } + + /** + * Gets the iteration types of an `Iterator`-like or `AsyncIterator`-like type from the + * cache or from common heuristics. + * + * If we previously analyzed this type and found no iteration types, `noIterationTypes` is + * returned. If we found iteration types, an `IterationTypes` record is returned. + * Otherwise, we return `undefined` to indicate to the caller it should perform a more + * exhaustive analysis. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterator` instead. + */ + function getIterationTypesOfIteratorFast(type: Type, resolver: IterationTypesResolver) { + // As an optimization, if the type is an instantiation of one of the following global types, + // then just grab its related type argument: + // - `IterableIterator` or `AsyncIterableIterator` + // - `Iterator` or `AsyncIterator` + // - `Generator` or `AsyncGenerator` + const globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false); + if (isReferenceToType(type, globalType)) { + const [yieldType] = getTypeArguments(type as GenericType); + // The "return" and "next" types of `IterableIterator` and `AsyncIterableIterator` are defined by the + // iteration types of their `next`, `return`, and `throw` methods. While we define these as `any` + // and `undefined` in our libs by default, a custom lib *could* use different definitions. + const globalIterationTypes = getIterationTypesOfIteratorCached(globalType, resolver) || + getIterationTypesOfIteratorSlow(globalType, resolver, /*errorNode*/ undefined, /*errorOutputContainer*/ undefined, /*noCache*/ false); + const { returnType, nextType } = globalIterationTypes === noIterationTypes ? defaultIterationTypes : globalIterationTypes; + return setCachedIterationTypes(type, resolver.iteratorCacheKey, createIterationTypes(yieldType, returnType, nextType)); + } + if ( + isReferenceToType(type, resolver.getGlobalIteratorType(/*reportErrors*/ false)) || + isReferenceToType(type, resolver.getGlobalGeneratorType(/*reportErrors*/ false)) + ) { + const [yieldType, returnType, nextType] = getTypeArguments(type as GenericType); + return setCachedIterationTypes(type, resolver.iteratorCacheKey, createIterationTypes(yieldType, returnType, nextType)); + } + } + + function isIteratorResult(type: Type, kind: IterationTypeKind.Yield | IterationTypeKind.Return) { + // From https://tc39.github.io/ecma262/#sec-iteratorresult-interface: + // > [done] is the result status of an iterator `next` method call. If the end of the iterator was reached `done` is `true`. + // > If the end was not reached `done` is `false` and a value is available. + // > If a `done` property (either own or inherited) does not exist, it is consider to have the value `false`. + const doneType = getTypeOfPropertyOfType(type, "done" as __String) || falseType; + return isTypeAssignableTo(kind === IterationTypeKind.Yield ? falseType : trueType, doneType); + } + + function isYieldIteratorResult(type: Type) { + return isIteratorResult(type, IterationTypeKind.Yield); + } + + function isReturnIteratorResult(type: Type) { + return isIteratorResult(type, IterationTypeKind.Return); + } + + /** + * Gets the *yield* and *return* types of an `IteratorResult`-like type. + * + * If we are unable to determine a *yield* or a *return* type, `noIterationTypes` is + * returned to indicate to the caller that it should handle the error. Otherwise, an + * `IterationTypes` record is returned. + */ + function getIterationTypesOfIteratorResult(type: Type) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + const cachedTypes = getCachedIterationTypes(type, "iterationTypesOfIteratorResult"); + if (cachedTypes) { + return cachedTypes; + } + + // As an optimization, if the type is an instantiation of one of the global `IteratorYieldResult` + // or `IteratorReturnResult` types, then just grab its type argument. + if (isReferenceToType(type, getGlobalIteratorYieldResultType(/*reportErrors*/ false))) { + const yieldType = getTypeArguments(type as GenericType)[0]; + return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", createIterationTypes(yieldType, /*returnType*/ undefined, /*nextType*/ undefined)); + } + if (isReferenceToType(type, getGlobalIteratorReturnResultType(/*reportErrors*/ false))) { + const returnType = getTypeArguments(type as GenericType)[0]; + return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", createIterationTypes(/*yieldType*/ undefined, returnType, /*nextType*/ undefined)); + } + + // Choose any constituents that can produce the requested iteration type. + const yieldIteratorResult = filterType(type, isYieldIteratorResult); + const yieldType = yieldIteratorResult !== neverType ? getTypeOfPropertyOfType(yieldIteratorResult, "value" as __String) : undefined; + + const returnIteratorResult = filterType(type, isReturnIteratorResult); + const returnType = returnIteratorResult !== neverType ? getTypeOfPropertyOfType(returnIteratorResult, "value" as __String) : undefined; + + if (!yieldType && !returnType) { + return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", noIterationTypes); + } + + // From https://tc39.github.io/ecma262/#sec-iteratorresult-interface + // > ... If the iterator does not have a return value, `value` is `undefined`. In that case, the + // > `value` property may be absent from the conforming object if it does not inherit an explicit + // > `value` property. + return setCachedIterationTypes(type, "iterationTypesOfIteratorResult", createIterationTypes(yieldType, returnType || voidType, /*nextType*/ undefined)); + } + + /** + * Gets the *yield*, *return*, and *next* types of a the `next()`, `return()`, or + * `throw()` method of an `Iterator`-like or `AsyncIterator`-like type. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, we return `undefined`. + */ + function getIterationTypesOfMethod(type: Type, resolver: IterationTypesResolver, methodName: "next" | "return" | "throw", errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined): IterationTypes | undefined { + const method = getPropertyOfType(type, methodName as __String); + + // Ignore 'return' or 'throw' if they are missing. + if (!method && methodName !== "next") { + return undefined; + } + + const methodType = method && !(methodName === "next" && (method.flags & SymbolFlags.Optional)) + ? methodName === "next" ? getTypeOfSymbol(method) : getTypeWithFacts(getTypeOfSymbol(method), TypeFacts.NEUndefinedOrNull) + : undefined; + + if (isTypeAny(methodType)) { + // `return()` and `throw()` don't provide a *next* type. + return methodName === "next" ? anyIterationTypes : anyIterationTypesExceptNext; + } + + // Both async and non-async iterators *must* have a `next` method. + const methodSignatures = methodType ? getSignaturesOfType(methodType, SignatureKind.Call) : emptyArray; + if (methodSignatures.length === 0) { + if (errorNode) { + const diagnostic = methodName === "next" + ? resolver.mustHaveANextMethodDiagnostic + : resolver.mustBeAMethodDiagnostic; + if (errorOutputContainer) { + errorOutputContainer.errors ??= []; + errorOutputContainer.errors.push(createDiagnosticForNode(errorNode, diagnostic, methodName)); + } + else { + error(errorNode, diagnostic, methodName); + } + } + return methodName === "next" ? noIterationTypes : undefined; + } + + // If the method signature comes exclusively from the global iterator or generator type, + // create iteration types from its type arguments like `getIterationTypesOfIteratorFast` + // does (so as to remove `undefined` from the next and return types). We arrive here when + // a contextual type for a generator was not a direct reference to one of those global types, + // but looking up `methodType` referred to one of them (and nothing else). E.g., in + // `interface SpecialIterator extends Iterator {}`, `SpecialIterator` is not a + // reference to `Iterator`, but its `next` member derives exclusively from `Iterator`. + if (methodType?.symbol && methodSignatures.length === 1) { + const globalGeneratorType = resolver.getGlobalGeneratorType(/*reportErrors*/ false); + const globalIteratorType = resolver.getGlobalIteratorType(/*reportErrors*/ false); + const isGeneratorMethod = globalGeneratorType.symbol?.members?.get(methodName as __String) === methodType.symbol; + const isIteratorMethod = !isGeneratorMethod && globalIteratorType.symbol?.members?.get(methodName as __String) === methodType.symbol; + if (isGeneratorMethod || isIteratorMethod) { + const globalType = isGeneratorMethod ? globalGeneratorType : globalIteratorType; + const { mapper } = methodType as AnonymousType; + return createIterationTypes( + getMappedType(globalType.typeParameters![0], mapper!), + getMappedType(globalType.typeParameters![1], mapper!), + methodName === "next" ? getMappedType(globalType.typeParameters![2], mapper!) : undefined, + ); + } + } + + // Extract the first parameter and return type of each signature. + let methodParameterTypes: Type[] | undefined; + let methodReturnTypes: Type[] | undefined; + for (const signature of methodSignatures) { + if (methodName !== "throw" && some(signature.parameters)) { + methodParameterTypes = append(methodParameterTypes, getTypeAtPosition(signature, 0)); + } + methodReturnTypes = append(methodReturnTypes, getReturnTypeOfSignature(signature)); + } + + // Resolve the *next* or *return* type from the first parameter of a `next()` or + // `return()` method, respectively. + let returnTypes: Type[] | undefined; + let nextType: Type | undefined; + if (methodName !== "throw") { + const methodParameterType = methodParameterTypes ? getUnionType(methodParameterTypes) : unknownType; + if (methodName === "next") { + // The value of `next(value)` is *not* awaited by async generators + nextType = methodParameterType; + } + else if (methodName === "return") { + // The value of `return(value)` *is* awaited by async generators + const resolvedMethodParameterType = resolver.resolveIterationType(methodParameterType, errorNode) || anyType; + returnTypes = append(returnTypes, resolvedMethodParameterType); + } + } + + // Resolve the *yield* and *return* types from the return type of the method (i.e. `IteratorResult`) + let yieldType: Type; + const methodReturnType = methodReturnTypes ? getIntersectionType(methodReturnTypes) : neverType; + const resolvedMethodReturnType = resolver.resolveIterationType(methodReturnType, errorNode) || anyType; + const iterationTypes = getIterationTypesOfIteratorResult(resolvedMethodReturnType); + if (iterationTypes === noIterationTypes) { + if (errorNode) { + if (errorOutputContainer) { + errorOutputContainer.errors ??= []; + errorOutputContainer.errors.push(createDiagnosticForNode(errorNode, resolver.mustHaveAValueDiagnostic, methodName)); + } + else { + error(errorNode, resolver.mustHaveAValueDiagnostic, methodName); + } + } + yieldType = anyType; + returnTypes = append(returnTypes, anyType); + } + else { + yieldType = iterationTypes.yieldType; + returnTypes = append(returnTypes, iterationTypes.returnType); + } + + return createIterationTypes(yieldType, getUnionType(returnTypes), nextType); + } + + /** + * Gets the *yield*, *return*, and *next* types of an `Iterator`-like or `AsyncIterator`-like + * type from its members. + * + * If we successfully found the *yield*, *return*, and *next* types, an `IterationTypes` + * record is returned. Otherwise, `noIterationTypes` is returned. + * + * NOTE: You probably don't want to call this directly and should be calling + * `getIterationTypesOfIterator` instead. + */ + function getIterationTypesOfIteratorSlow(type: Type, resolver: IterationTypesResolver, errorNode: Node | undefined, errorOutputContainer: { errors: Diagnostic[] | undefined; } | undefined, noCache: boolean) { + const iterationTypes = combineIterationTypes([ + getIterationTypesOfMethod(type, resolver, "next", errorNode, errorOutputContainer), + getIterationTypesOfMethod(type, resolver, "return", errorNode, errorOutputContainer), + getIterationTypesOfMethod(type, resolver, "throw", errorNode, errorOutputContainer), + ]); + return noCache ? iterationTypes : setCachedIterationTypes(type, resolver.iteratorCacheKey, iterationTypes); + } + + /** + * Gets the requested "iteration type" from a type that is either `Iterable`-like, `Iterator`-like, + * `IterableIterator`-like, or `Generator`-like (for a non-async generator); or `AsyncIterable`-like, + * `AsyncIterator`-like, `AsyncIterableIterator`-like, or `AsyncGenerator`-like (for an async generator). + */ + function getIterationTypeOfGeneratorFunctionReturnType(kind: IterationTypeKind, returnType: Type, isAsyncGenerator: boolean): Type | undefined { + if (isTypeAny(returnType)) { + return undefined; + } + + const iterationTypes = getIterationTypesOfGeneratorFunctionReturnType(returnType, isAsyncGenerator); + return iterationTypes && iterationTypes[getIterationTypesKeyFromIterationTypeKind(kind)]; + } + + function getIterationTypesOfGeneratorFunctionReturnType(type: Type, isAsyncGenerator: boolean) { + if (isTypeAny(type)) { + return anyIterationTypes; + } + + const use = isAsyncGenerator ? IterationUse.AsyncGeneratorReturnType : IterationUse.GeneratorReturnType; + const resolver = isAsyncGenerator ? asyncIterationTypesResolver : syncIterationTypesResolver; + return getIterationTypesOfIterable(type, use, /*errorNode*/ undefined) || + getIterationTypesOfIterator(type, resolver, /*errorNode*/ undefined, /*errorOutputContainer*/ undefined); + } + + function checkBreakOrContinueStatement(node: BreakOrContinueStatement) { + // Grammar checking + if (!checkGrammarStatementInAmbientContext(node)) checkGrammarBreakOrContinueStatement(node); + + // TODO: Check that target label is valid + } + + function unwrapReturnType(returnType: Type, functionFlags: FunctionFlags) { + const isGenerator = !!(functionFlags & FunctionFlags.Generator); + const isAsync = !!(functionFlags & FunctionFlags.Async); + if (isGenerator) { + const returnIterationType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, returnType, isAsync); + if (!returnIterationType) { + return errorType; + } + return isAsync ? getAwaitedTypeNoAlias(unwrapAwaitedType(returnIterationType)) : returnIterationType; + } + return isAsync ? getAwaitedTypeNoAlias(returnType) || errorType : returnType; + } + + function isUnwrappedReturnTypeUndefinedVoidOrAny(func: SignatureDeclaration, returnType: Type): boolean { + const type = unwrapReturnType(returnType, getFunctionFlags(func)); + return !!(type && (maybeTypeOfKind(type, TypeFlags.Void) || type.flags & (TypeFlags.Any | TypeFlags.Undefined))); + } + + function checkReturnStatement(node: ReturnStatement) { + // Grammar checking + if (checkGrammarStatementInAmbientContext(node)) { + return; + } + + const container = getContainingFunctionOrClassStaticBlock(node); + if (container && isClassStaticBlockDeclaration(container)) { + grammarErrorOnFirstToken(node, Diagnostics.A_return_statement_cannot_be_used_inside_a_class_static_block); + return; + } + + if (!container) { + grammarErrorOnFirstToken(node, Diagnostics.A_return_statement_can_only_be_used_within_a_function_body); + return; + } + + const signature = getSignatureFromDeclaration(container); + const returnType = getReturnTypeOfSignature(signature); + const functionFlags = getFunctionFlags(container); + if (strictNullChecks || node.expression || returnType.flags & TypeFlags.Never) { + const exprType = node.expression ? checkExpressionCached(node.expression) : undefinedType; + if (container.kind === SyntaxKind.SetAccessor) { + if (node.expression) { + error(node, Diagnostics.Setters_cannot_return_a_value); + } + } + else if (container.kind === SyntaxKind.Constructor) { + if (node.expression && !checkTypeAssignableToAndOptionallyElaborate(exprType, returnType, node, node.expression)) { + error(node, Diagnostics.Return_type_of_constructor_signature_must_be_assignable_to_the_instance_type_of_the_class); + } + } + else if (getReturnTypeFromAnnotation(container)) { + const unwrappedReturnType = unwrapReturnType(returnType, functionFlags) ?? returnType; + const unwrappedExprType = functionFlags & FunctionFlags.Async + ? checkAwaitedType(exprType, /*withAlias*/ false, node, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member) + : exprType; + if (unwrappedReturnType) { + // If the function has a return type, but promisedType is + // undefined, an error will be reported in checkAsyncFunctionReturnType + // so we don't need to report one here. + checkTypeAssignableToAndOptionallyElaborate(unwrappedExprType, unwrappedReturnType, node, node.expression); + } + } + } + else if (container.kind !== SyntaxKind.Constructor && compilerOptions.noImplicitReturns && !isUnwrappedReturnTypeUndefinedVoidOrAny(container, returnType)) { + // The function has a return type, but the return statement doesn't have an expression. + error(node, Diagnostics.Not_all_code_paths_return_a_value); + } + } + + function checkWithStatement(node: WithStatement) { + // Grammar checking for withStatement + if (!checkGrammarStatementInAmbientContext(node)) { + if (node.flags & NodeFlags.AwaitContext) { + grammarErrorOnFirstToken(node, Diagnostics.with_statements_are_not_allowed_in_an_async_function_block); + } + } + + checkExpression(node.expression); + + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + const start = getSpanOfTokenAtPosition(sourceFile, node.pos).start; + const end = node.statement.pos; + grammarErrorAtPos(sourceFile, start, end - start, Diagnostics.The_with_statement_is_not_supported_All_symbols_in_a_with_block_will_have_type_any); + } + } + + function checkSwitchStatement(node: SwitchStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + let firstDefaultClause: CaseOrDefaultClause; + let hasDuplicateDefaultClause = false; + + const expressionType = checkExpression(node.expression); + + forEach(node.caseBlock.clauses, clause => { + // Grammar check for duplicate default clauses, skip if we already report duplicate default clause + if (clause.kind === SyntaxKind.DefaultClause && !hasDuplicateDefaultClause) { + if (firstDefaultClause === undefined) { + firstDefaultClause = clause; + } + else { + grammarErrorOnNode(clause, Diagnostics.A_default_clause_cannot_appear_more_than_once_in_a_switch_statement); + hasDuplicateDefaultClause = true; + } + } + + if (clause.kind === SyntaxKind.CaseClause) { + addLazyDiagnostic(createLazyCaseClauseDiagnostics(clause)); + } + forEach(clause.statements, checkSourceElement); + if (compilerOptions.noFallthroughCasesInSwitch && clause.fallthroughFlowNode && isReachableFlowNode(clause.fallthroughFlowNode)) { + error(clause, Diagnostics.Fallthrough_case_in_switch); + } + + function createLazyCaseClauseDiagnostics(clause: CaseClause) { + return () => { + // TypeScript 1.0 spec (April 2014): 5.9 + // In a 'switch' statement, each 'case' expression must be of a type that is comparable + // to or from the type of the 'switch' expression. + const caseType = checkExpression(clause.expression); + + if (!isTypeEqualityComparableTo(expressionType, caseType)) { + // expressionType is not comparable to caseType, try the reversed check and report errors if it fails + checkTypeComparableTo(caseType, expressionType, clause.expression, /*headMessage*/ undefined); + } + }; + } + }); + if (node.caseBlock.locals) { + registerForUnusedIdentifiersCheck(node.caseBlock); + } + } + + function checkLabeledStatement(node: LabeledStatement) { + // Grammar checking + if (!checkGrammarStatementInAmbientContext(node)) { + findAncestor(node.parent, current => { + if (isFunctionLike(current)) { + return "quit"; + } + if (current.kind === SyntaxKind.LabeledStatement && (current as LabeledStatement).label.escapedText === node.label.escapedText) { + grammarErrorOnNode(node.label, Diagnostics.Duplicate_label_0, getTextOfNode(node.label)); + return true; + } + return false; + }); + } + + // ensure that label is unique + checkSourceElement(node.statement); + } + + function checkThrowStatement(node: ThrowStatement) { + // Grammar checking + if (!checkGrammarStatementInAmbientContext(node)) { + if (isIdentifier(node.expression) && !node.expression.escapedText) { + grammarErrorAfterFirstToken(node, Diagnostics.Line_break_not_permitted_here); + } + } + + if (node.expression) { + checkExpression(node.expression); + } + } + + function checkTryStatement(node: TryStatement) { + // Grammar checking + checkGrammarStatementInAmbientContext(node); + + checkBlock(node.tryBlock); + const catchClause = node.catchClause; + if (catchClause) { + // Grammar checking + if (catchClause.variableDeclaration) { + const declaration = catchClause.variableDeclaration; + checkVariableLikeDeclaration(declaration); + const typeNode = getEffectiveTypeAnnotationNode(declaration); + if (typeNode) { + const type = getTypeFromTypeNode(typeNode); + if (type && !(type.flags & TypeFlags.AnyOrUnknown)) { + grammarErrorOnFirstToken(typeNode, Diagnostics.Catch_clause_variable_type_annotation_must_be_any_or_unknown_if_specified); + } + } + else if (declaration.initializer) { + grammarErrorOnFirstToken(declaration.initializer, Diagnostics.Catch_clause_variable_cannot_have_an_initializer); + } + else { + const blockLocals = catchClause.block.locals; + if (blockLocals) { + forEachKey(catchClause.locals!, caughtName => { + const blockLocal = blockLocals.get(caughtName); + if (blockLocal?.valueDeclaration && (blockLocal.flags & SymbolFlags.BlockScopedVariable) !== 0) { + grammarErrorOnNode(blockLocal.valueDeclaration, Diagnostics.Cannot_redeclare_identifier_0_in_catch_clause, unescapeLeadingUnderscores(caughtName)); + } + }); + } + } + } + + checkBlock(catchClause.block); + } + + if (node.finallyBlock) { + checkBlock(node.finallyBlock); + } + } + + function checkIndexConstraints(type: Type, symbol: Symbol, isStaticIndex?: boolean) { + const indexInfos = getIndexInfosOfType(type); + if (indexInfos.length === 0) { + return; + } + for (const prop of getPropertiesOfObjectType(type)) { + if (!(isStaticIndex && prop.flags & SymbolFlags.Prototype)) { + checkIndexConstraintForProperty(type, prop, getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique, /*includeNonPublic*/ true), getNonMissingTypeOfSymbol(prop)); + } + } + const typeDeclaration = symbol.valueDeclaration; + if (typeDeclaration && isClassLike(typeDeclaration)) { + for (const member of typeDeclaration.members) { + // Only process instance properties with computed names here. Static properties cannot be in conflict with indexers, + // and properties with literal names were already checked. + if (!isStatic(member) && !hasBindableName(member)) { + const symbol = getSymbolOfDeclaration(member); + checkIndexConstraintForProperty(type, symbol, getTypeOfExpression((member as DynamicNamedDeclaration).name.expression), getNonMissingTypeOfSymbol(symbol)); + } + } + } + if (indexInfos.length > 1) { + for (const info of indexInfos) { + checkIndexConstraintForIndexSignature(type, info); + } + } + } + + function checkIndexConstraintForProperty(type: Type, prop: Symbol, propNameType: Type, propType: Type) { + const declaration = prop.valueDeclaration; + const name = getNameOfDeclaration(declaration); + if (name && isPrivateIdentifier(name)) { + return; + } + const indexInfos = getApplicableIndexInfos(type, propNameType); + const interfaceDeclaration = getObjectFlags(type) & ObjectFlags.Interface ? getDeclarationOfKind(type.symbol, SyntaxKind.InterfaceDeclaration) : undefined; + const propDeclaration = declaration && declaration.kind === SyntaxKind.BinaryExpression || + name && name.kind === SyntaxKind.ComputedPropertyName ? declaration : undefined; + const localPropDeclaration = getParentOfSymbol(prop) === type.symbol ? declaration : undefined; + for (const info of indexInfos) { + const localIndexDeclaration = info.declaration && getParentOfSymbol(getSymbolOfDeclaration(info.declaration)) === type.symbol ? info.declaration : undefined; + // We check only when (a) the property is declared in the containing type, or (b) the applicable index signature is declared + // in the containing type, or (c) the containing type is an interface and no base interface contains both the property and + // the index signature (i.e. property and index signature are declared in separate inherited interfaces). + const errorNode = localPropDeclaration || localIndexDeclaration || + (interfaceDeclaration && !some(getBaseTypes(type as InterfaceType), base => !!getPropertyOfObjectType(base, prop.escapedName) && !!getIndexTypeOfType(base, info.keyType)) ? interfaceDeclaration : undefined); + if (errorNode && !isTypeAssignableTo(propType, info.type)) { + const diagnostic = createError(errorNode, Diagnostics.Property_0_of_type_1_is_not_assignable_to_2_index_type_3, symbolToString(prop), typeToString(propType), typeToString(info.keyType), typeToString(info.type)); + if (propDeclaration && errorNode !== propDeclaration) { + addRelatedInfo(diagnostic, createDiagnosticForNode(propDeclaration, Diagnostics._0_is_declared_here, symbolToString(prop))); + } + diagnostics.add(diagnostic); + } + } + } + + function checkIndexConstraintForIndexSignature(type: Type, checkInfo: IndexInfo) { + const declaration = checkInfo.declaration; + const indexInfos = getApplicableIndexInfos(type, checkInfo.keyType); + const interfaceDeclaration = getObjectFlags(type) & ObjectFlags.Interface ? getDeclarationOfKind(type.symbol, SyntaxKind.InterfaceDeclaration) : undefined; + const localCheckDeclaration = declaration && getParentOfSymbol(getSymbolOfDeclaration(declaration)) === type.symbol ? declaration : undefined; + for (const info of indexInfos) { + if (info === checkInfo) continue; + const localIndexDeclaration = info.declaration && getParentOfSymbol(getSymbolOfDeclaration(info.declaration)) === type.symbol ? info.declaration : undefined; + // We check only when (a) the check index signature is declared in the containing type, or (b) the applicable index + // signature is declared in the containing type, or (c) the containing type is an interface and no base interface contains + // both index signatures (i.e. the index signatures are declared in separate inherited interfaces). + const errorNode = localCheckDeclaration || localIndexDeclaration || + (interfaceDeclaration && !some(getBaseTypes(type as InterfaceType), base => !!getIndexInfoOfType(base, checkInfo.keyType) && !!getIndexTypeOfType(base, info.keyType)) ? interfaceDeclaration : undefined); + if (errorNode && !isTypeAssignableTo(checkInfo.type, info.type)) { + error(errorNode, Diagnostics._0_index_type_1_is_not_assignable_to_2_index_type_3, typeToString(checkInfo.keyType), typeToString(checkInfo.type), typeToString(info.keyType), typeToString(info.type)); + } + } + } + + function checkTypeNameIsReserved(name: Identifier, message: DiagnosticMessage): void { + // TS 1.0 spec (April 2014): 3.6.1 + // The predefined type keywords are reserved and cannot be used as names of user defined types. + switch (name.escapedText) { + case "any": + case "unknown": + case "never": + case "number": + case "bigint": + case "boolean": + case "string": + case "symbol": + case "void": + case "object": + case "undefined": + error(name, message, name.escapedText as string); + } + } + + /** + * The name cannot be used as 'Object' of user defined types with special target. + */ + function checkClassNameCollisionWithObject(name: Identifier): void { + if ( + languageVersion >= ScriptTarget.ES5 && name.escapedText === "Object" + && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(name).impliedNodeFormat === ModuleKind.CommonJS) + ) { + error(name, Diagnostics.Class_name_cannot_be_Object_when_targeting_ES5_with_module_0, ModuleKind[moduleKind]); // https://github.com/Microsoft/TypeScript/issues/17494 + } + } + + function checkUnmatchedJSDocParameters(node: SignatureDeclaration) { + const jsdocParameters = filter(getJSDocTags(node), isJSDocParameterTag); + if (!length(jsdocParameters)) return; + + const isJs = isInJSFile(node); + const parameters = new Set<__String>(); + const excludedParameters = new Set(); + forEach(node.parameters, ({ name }, index) => { + if (isIdentifier(name)) { + parameters.add(name.escapedText); + } + if (isBindingPattern(name)) { + excludedParameters.add(index); + } + }); + + const containsArguments = containsArgumentsReference(node); + if (containsArguments) { + const lastJSDocParamIndex = jsdocParameters.length - 1; + const lastJSDocParam = jsdocParameters[lastJSDocParamIndex]; + if ( + isJs && lastJSDocParam && isIdentifier(lastJSDocParam.name) && lastJSDocParam.typeExpression && + lastJSDocParam.typeExpression.type && !parameters.has(lastJSDocParam.name.escapedText) && !excludedParameters.has(lastJSDocParamIndex) && !isArrayType(getTypeFromTypeNode(lastJSDocParam.typeExpression.type)) + ) { + error(lastJSDocParam.name, Diagnostics.JSDoc_param_tag_has_name_0_but_there_is_no_parameter_with_that_name_It_would_match_arguments_if_it_had_an_array_type, idText(lastJSDocParam.name)); + } + } + else { + forEach(jsdocParameters, ({ name, isNameFirst }, index) => { + if (excludedParameters.has(index) || isIdentifier(name) && parameters.has(name.escapedText)) { + return; + } + if (isQualifiedName(name)) { + if (isJs) { + error(name, Diagnostics.Qualified_name_0_is_not_allowed_without_a_leading_param_object_1, entityNameToString(name), entityNameToString(name.left)); + } + } + else { + if (!isNameFirst) { + errorOrSuggestion(isJs, name, Diagnostics.JSDoc_param_tag_has_name_0_but_there_is_no_parameter_with_that_name, idText(name)); + } + } + }); + } + } + + /** + * Check each type parameter and check that type parameters have no duplicate type parameter declarations + */ + function checkTypeParameters(typeParameterDeclarations: readonly TypeParameterDeclaration[] | undefined) { + let seenDefault = false; + if (typeParameterDeclarations) { + for (let i = 0; i < typeParameterDeclarations.length; i++) { + const node = typeParameterDeclarations[i]; + checkTypeParameter(node); + + addLazyDiagnostic(createCheckTypeParameterDiagnostic(node, i)); + } + } + + function createCheckTypeParameterDiagnostic(node: TypeParameterDeclaration, i: number) { + return () => { + if (node.default) { + seenDefault = true; + checkTypeParametersNotReferenced(node.default, typeParameterDeclarations!, i); + } + else if (seenDefault) { + error(node, Diagnostics.Required_type_parameters_may_not_follow_optional_type_parameters); + } + for (let j = 0; j < i; j++) { + if (typeParameterDeclarations![j].symbol === node.symbol) { + error(node.name, Diagnostics.Duplicate_identifier_0, declarationNameToString(node.name)); + } + } + }; + } + } + + /** Check that type parameter defaults only reference previously declared type parameters */ + function checkTypeParametersNotReferenced(root: TypeNode, typeParameters: readonly TypeParameterDeclaration[], index: number) { + visit(root); + function visit(node: Node) { + if (node.kind === SyntaxKind.TypeReference) { + const type = getTypeFromTypeReference(node as TypeReferenceNode); + if (type.flags & TypeFlags.TypeParameter) { + for (let i = index; i < typeParameters.length; i++) { + if (type.symbol === getSymbolOfDeclaration(typeParameters[i])) { + error(node, Diagnostics.Type_parameter_defaults_can_only_reference_previously_declared_type_parameters); + } + } + } + } + forEachChild(node, visit); + } + } + + /** Check that type parameter lists are identical across multiple declarations */ + function checkTypeParameterListsIdentical(symbol: Symbol) { + if (symbol.declarations && symbol.declarations.length === 1) { + return; + } + + const links = getSymbolLinks(symbol); + if (!links.typeParametersChecked) { + links.typeParametersChecked = true; + const declarations = getClassOrInterfaceDeclarationsOfSymbol(symbol); + if (!declarations || declarations.length <= 1) { + return; + } + + const type = getDeclaredTypeOfSymbol(symbol) as InterfaceType; + if (!areTypeParametersIdentical(declarations, type.localTypeParameters!, getEffectiveTypeParameterDeclarations)) { + // Report an error on every conflicting declaration. + const name = symbolToString(symbol); + for (const declaration of declarations) { + error(declaration.name, Diagnostics.All_declarations_of_0_must_have_identical_type_parameters, name); + } + } + } + } + + function areTypeParametersIdentical(declarations: readonly T[], targetParameters: TypeParameter[], getTypeParameterDeclarations: (node: T) => readonly TypeParameterDeclaration[]) { + const maxTypeArgumentCount = length(targetParameters); + const minTypeArgumentCount = getMinTypeArgumentCount(targetParameters); + + for (const declaration of declarations) { + // If this declaration has too few or too many type parameters, we report an error + const sourceParameters = getTypeParameterDeclarations(declaration); + const numTypeParameters = sourceParameters.length; + if (numTypeParameters < minTypeArgumentCount || numTypeParameters > maxTypeArgumentCount) { + return false; + } + + for (let i = 0; i < numTypeParameters; i++) { + const source = sourceParameters[i]; + const target = targetParameters[i]; + + // If the type parameter node does not have the same as the resolved type + // parameter at this position, we report an error. + if (source.name.escapedText !== target.symbol.escapedName) { + return false; + } + + // If the type parameter node does not have an identical constraint as the resolved + // type parameter at this position, we report an error. + const constraint = getEffectiveConstraintOfTypeParameter(source); + const sourceConstraint = constraint && getTypeFromTypeNode(constraint); + const targetConstraint = getConstraintOfTypeParameter(target); + // relax check if later interface augmentation has no constraint, it's more broad and is OK to merge with + // a more constrained interface (this could be generalized to a full hierarchy check, but that's maybe overkill) + if (sourceConstraint && targetConstraint && !isTypeIdenticalTo(sourceConstraint, targetConstraint)) { + return false; + } + + // If the type parameter node has a default and it is not identical to the default + // for the type parameter at this position, we report an error. + const sourceDefault = source.default && getTypeFromTypeNode(source.default); + const targetDefault = getDefaultFromTypeParameter(target); + if (sourceDefault && targetDefault && !isTypeIdenticalTo(sourceDefault, targetDefault)) { + return false; + } + } + } + + return true; + } + + function getFirstTransformableStaticClassElement(node: ClassLikeDeclaration) { + const willTransformStaticElementsOfDecoratedClass = !legacyDecorators && languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators && + classOrConstructorParameterIsDecorated(/*useLegacyDecorators*/ false, node); + const willTransformPrivateElementsOrClassStaticBlocks = languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators; + const willTransformInitializers = !emitStandardClassFields; + if (willTransformStaticElementsOfDecoratedClass || willTransformPrivateElementsOrClassStaticBlocks) { + for (const member of node.members) { + if (willTransformStaticElementsOfDecoratedClass && classElementOrClassElementParameterIsDecorated(/*useLegacyDecorators*/ false, member, node)) { + return firstOrUndefined(getDecorators(node)) ?? node; + } + else if (willTransformPrivateElementsOrClassStaticBlocks) { + if (isClassStaticBlockDeclaration(member)) { + return member; + } + else if (isStatic(member)) { + if ( + isPrivateIdentifierClassElementDeclaration(member) || + willTransformInitializers && isInitializedProperty(member) + ) { + return member; + } + } + } + } + } + } + + function checkClassExpressionExternalHelpers(node: ClassExpression) { + if (node.name) return; + + const parent = walkUpOuterExpressions(node); + if (!isNamedEvaluationSource(parent)) return; + + const willTransformESDecorators = !legacyDecorators && languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators; + let location: Node | undefined; + if (willTransformESDecorators && classOrConstructorParameterIsDecorated(/*useLegacyDecorators*/ false, node)) { + location = firstOrUndefined(getDecorators(node)) ?? node; + } + else { + location = getFirstTransformableStaticClassElement(node); + } + + if (location) { + checkExternalEmitHelpers(location, ExternalEmitHelpers.SetFunctionName); + if ((isPropertyAssignment(parent) || isPropertyDeclaration(parent) || isBindingElement(parent)) && isComputedPropertyName(parent.name)) { + checkExternalEmitHelpers(location, ExternalEmitHelpers.PropKey); + } + } + } + + function checkClassExpression(node: ClassExpression): Type { + checkClassLikeDeclaration(node); + checkNodeDeferred(node); + checkClassExpressionExternalHelpers(node); + return getTypeOfSymbol(getSymbolOfDeclaration(node)); + } + + function checkClassExpressionDeferred(node: ClassExpression) { + forEach(node.members, checkSourceElement); + registerForUnusedIdentifiersCheck(node); + } + + function checkClassDeclaration(node: ClassDeclaration) { + const firstDecorator = find(node.modifiers, isDecorator); + if (legacyDecorators && firstDecorator && some(node.members, p => hasStaticModifier(p) && isPrivateIdentifierClassElementDeclaration(p))) { + grammarErrorOnNode(firstDecorator, Diagnostics.Class_decorators_can_t_be_used_with_static_private_identifier_Consider_removing_the_experimental_decorator); + } + if (!node.name && !hasSyntacticModifier(node, ModifierFlags.Default)) { + grammarErrorOnFirstToken(node, Diagnostics.A_class_declaration_without_the_default_modifier_must_have_a_name); + } + checkClassLikeDeclaration(node); + forEach(node.members, checkSourceElement); + + registerForUnusedIdentifiersCheck(node); + } + + function checkClassLikeDeclaration(node: ClassLikeDeclaration) { + checkGrammarClassLikeDeclaration(node); + checkDecorators(node); + checkCollisionsForDeclarationName(node, node.name); + checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); + checkExportsOnMergedDeclarations(node); + const symbol = getSymbolOfDeclaration(node); + const type = getDeclaredTypeOfSymbol(symbol) as InterfaceType; + const typeWithThis = getTypeWithThisArgument(type); + const staticType = getTypeOfSymbol(symbol) as ObjectType; + checkTypeParameterListsIdentical(symbol); + checkFunctionOrConstructorSymbol(symbol); + checkClassForDuplicateDeclarations(node); + + // Only check for reserved static identifiers on non-ambient context. + const nodeInAmbientContext = !!(node.flags & NodeFlags.Ambient); + if (!nodeInAmbientContext) { + checkClassForStaticPropertyNameConflicts(node); + } + + const baseTypeNode = getEffectiveBaseTypeNode(node); + if (baseTypeNode) { + forEach(baseTypeNode.typeArguments, checkSourceElement); + if (languageVersion < LanguageFeatureMinimumTarget.Classes) { + checkExternalEmitHelpers(baseTypeNode.parent, ExternalEmitHelpers.Extends); + } + // check both @extends and extends if both are specified. + const extendsNode = getClassExtendsHeritageElement(node); + if (extendsNode && extendsNode !== baseTypeNode) { + checkExpression(extendsNode.expression); + } + + const baseTypes = getBaseTypes(type); + if (baseTypes.length) { + addLazyDiagnostic(() => { + const baseType = baseTypes[0]; + const baseConstructorType = getBaseConstructorTypeOfClass(type); + const staticBaseType = getApparentType(baseConstructorType); + checkBaseTypeAccessibility(staticBaseType, baseTypeNode); + checkSourceElement(baseTypeNode.expression); + if (some(baseTypeNode.typeArguments)) { + forEach(baseTypeNode.typeArguments, checkSourceElement); + for (const constructor of getConstructorsForTypeArguments(staticBaseType, baseTypeNode.typeArguments, baseTypeNode)) { + if (!checkTypeArgumentConstraints(baseTypeNode, constructor.typeParameters!)) { + break; + } + } + } + const baseWithThis = getTypeWithThisArgument(baseType, type.thisType); + if (!checkTypeAssignableTo(typeWithThis, baseWithThis, /*errorNode*/ undefined)) { + issueMemberSpecificError(node, typeWithThis, baseWithThis, Diagnostics.Class_0_incorrectly_extends_base_class_1); + } + else { + // Report static side error only when instance type is assignable + checkTypeAssignableTo(staticType, getTypeWithoutSignatures(staticBaseType), node.name || node, Diagnostics.Class_static_side_0_incorrectly_extends_base_class_static_side_1); + } + if (baseConstructorType.flags & TypeFlags.TypeVariable) { + if (!isMixinConstructorType(staticType)) { + error(node.name || node, Diagnostics.A_mixin_class_must_have_a_constructor_with_a_single_rest_parameter_of_type_any); + } + else { + const constructSignatures = getSignaturesOfType(baseConstructorType, SignatureKind.Construct); + if (constructSignatures.some(signature => signature.flags & SignatureFlags.Abstract) && !hasSyntacticModifier(node, ModifierFlags.Abstract)) { + error(node.name || node, Diagnostics.A_mixin_class_that_extends_from_a_type_variable_containing_an_abstract_construct_signature_must_also_be_declared_abstract); + } + } + } + + if (!(staticBaseType.symbol && staticBaseType.symbol.flags & SymbolFlags.Class) && !(baseConstructorType.flags & TypeFlags.TypeVariable)) { + // When the static base type is a "class-like" constructor function (but not actually a class), we verify + // that all instantiated base constructor signatures return the same type. + const constructors = getInstantiatedConstructorsForTypeArguments(staticBaseType, baseTypeNode.typeArguments, baseTypeNode); + if (forEach(constructors, sig => !isJSConstructor(sig.declaration) && !isTypeIdenticalTo(getReturnTypeOfSignature(sig), baseType))) { + error(baseTypeNode.expression, Diagnostics.Base_constructors_must_all_have_the_same_return_type); + } + } + checkKindsOfPropertyMemberOverrides(type, baseType); + }); + } + } + + checkMembersForOverrideModifier(node, type, typeWithThis, staticType); + + const implementedTypeNodes = getEffectiveImplementsTypeNodes(node); + if (implementedTypeNodes) { + for (const typeRefNode of implementedTypeNodes) { + if (!isEntityNameExpression(typeRefNode.expression) || isOptionalChain(typeRefNode.expression)) { + error(typeRefNode.expression, Diagnostics.A_class_can_only_implement_an_identifier_Slashqualified_name_with_optional_type_arguments); + } + checkTypeReferenceNode(typeRefNode); + addLazyDiagnostic(createImplementsDiagnostics(typeRefNode)); + } + } + + addLazyDiagnostic(() => { + checkIndexConstraints(type, symbol); + checkIndexConstraints(staticType, symbol, /*isStaticIndex*/ true); + checkTypeForDuplicateIndexSignatures(node); + checkPropertyInitialization(node); + }); + + function createImplementsDiagnostics(typeRefNode: ExpressionWithTypeArguments) { + return () => { + const t = getReducedType(getTypeFromTypeNode(typeRefNode)); + if (!isErrorType(t)) { + if (isValidBaseType(t)) { + const genericDiag = t.symbol && t.symbol.flags & SymbolFlags.Class ? + Diagnostics.Class_0_incorrectly_implements_class_1_Did_you_mean_to_extend_1_and_inherit_its_members_as_a_subclass : + Diagnostics.Class_0_incorrectly_implements_interface_1; + const baseWithThis = getTypeWithThisArgument(t, type.thisType); + if (!checkTypeAssignableTo(typeWithThis, baseWithThis, /*errorNode*/ undefined)) { + issueMemberSpecificError(node, typeWithThis, baseWithThis, genericDiag); + } + } + else { + error(typeRefNode, Diagnostics.A_class_can_only_implement_an_object_type_or_intersection_of_object_types_with_statically_known_members); + } + } + }; + } + } + + function checkMembersForOverrideModifier(node: ClassLikeDeclaration, type: InterfaceType, typeWithThis: Type, staticType: ObjectType) { + const baseTypeNode = getEffectiveBaseTypeNode(node); + const baseTypes = baseTypeNode && getBaseTypes(type); + const baseWithThis = baseTypes?.length ? getTypeWithThisArgument(first(baseTypes), type.thisType) : undefined; + const baseStaticType = getBaseConstructorTypeOfClass(type); + + for (const member of node.members) { + if (hasAmbientModifier(member)) { + continue; + } + + if (isConstructorDeclaration(member)) { + forEach(member.parameters, param => { + if (isParameterPropertyDeclaration(param, member)) { + checkExistingMemberForOverrideModifier( + node, + staticType, + baseStaticType, + baseWithThis, + type, + typeWithThis, + param, + /*memberIsParameterProperty*/ true, + ); + } + }); + } + checkExistingMemberForOverrideModifier( + node, + staticType, + baseStaticType, + baseWithThis, + type, + typeWithThis, + member, + /*memberIsParameterProperty*/ false, + ); + } + } + + /** + * @param member Existing member node to be checked. + * Note: `member` cannot be a synthetic node. + */ + function checkExistingMemberForOverrideModifier( + node: ClassLikeDeclaration, + staticType: ObjectType, + baseStaticType: Type, + baseWithThis: Type | undefined, + type: InterfaceType, + typeWithThis: Type, + member: ClassElement | ParameterPropertyDeclaration, + memberIsParameterProperty: boolean, + reportErrors = true, + ): MemberOverrideStatus { + const declaredProp = member.name + && getSymbolAtLocation(member.name) + || getSymbolAtLocation(member); + if (!declaredProp) { + return MemberOverrideStatus.Ok; + } + + return checkMemberForOverrideModifier( + node, + staticType, + baseStaticType, + baseWithThis, + type, + typeWithThis, + hasOverrideModifier(member), + hasAbstractModifier(member), + isStatic(member), + memberIsParameterProperty, + declaredProp, + reportErrors ? member : undefined, + ); + } + + /** + * Checks a class member declaration for either a missing or an invalid `override` modifier. + * Note: this function can be used for speculative checking, + * i.e. checking a member that does not yet exist in the program. + * An example of that would be to call this function in a completions scenario, + * when offering a method declaration as completion. + * @param errorNode The node where we should report an error, or undefined if we should not report errors. + */ + function checkMemberForOverrideModifier( + node: ClassLikeDeclaration, + staticType: ObjectType, + baseStaticType: Type, + baseWithThis: Type | undefined, + type: InterfaceType, + typeWithThis: Type, + memberHasOverrideModifier: boolean, + memberHasAbstractModifier: boolean, + memberIsStatic: boolean, + memberIsParameterProperty: boolean, + member: Symbol, + errorNode?: Node, + ): MemberOverrideStatus { + const isJs = isInJSFile(node); + const nodeInAmbientContext = !!(node.flags & NodeFlags.Ambient); + if (baseWithThis && (memberHasOverrideModifier || compilerOptions.noImplicitOverride)) { + const thisType = memberIsStatic ? staticType : typeWithThis; + const baseType = memberIsStatic ? baseStaticType : baseWithThis; + const prop = getPropertyOfType(thisType, member.escapedName); + const baseProp = getPropertyOfType(baseType, member.escapedName); + + const baseClassName = typeToString(baseWithThis); + if (prop && !baseProp && memberHasOverrideModifier) { + if (errorNode) { + const suggestion = getSuggestedSymbolForNonexistentClassMember(symbolName(member), baseType); // Again, using symbol name: note that's different from `symbol.escapedName` + suggestion ? + error( + errorNode, + isJs ? + Diagnostics.This_member_cannot_have_a_JSDoc_comment_with_an_override_tag_because_it_is_not_declared_in_the_base_class_0_Did_you_mean_1 : + Diagnostics.This_member_cannot_have_an_override_modifier_because_it_is_not_declared_in_the_base_class_0_Did_you_mean_1, + baseClassName, + symbolToString(suggestion), + ) : + error( + errorNode, + isJs ? + Diagnostics.This_member_cannot_have_a_JSDoc_comment_with_an_override_tag_because_it_is_not_declared_in_the_base_class_0 : + Diagnostics.This_member_cannot_have_an_override_modifier_because_it_is_not_declared_in_the_base_class_0, + baseClassName, + ); + } + return MemberOverrideStatus.HasInvalidOverride; + } + else if (prop && baseProp?.declarations && compilerOptions.noImplicitOverride && !nodeInAmbientContext) { + const baseHasAbstract = some(baseProp.declarations, hasAbstractModifier); + if (memberHasOverrideModifier) { + return MemberOverrideStatus.Ok; + } + + if (!baseHasAbstract) { + if (errorNode) { + const diag = memberIsParameterProperty ? + isJs ? + Diagnostics.This_parameter_property_must_have_a_JSDoc_comment_with_an_override_tag_because_it_overrides_a_member_in_the_base_class_0 : + Diagnostics.This_parameter_property_must_have_an_override_modifier_because_it_overrides_a_member_in_base_class_0 : + isJs ? + Diagnostics.This_member_must_have_a_JSDoc_comment_with_an_override_tag_because_it_overrides_a_member_in_the_base_class_0 : + Diagnostics.This_member_must_have_an_override_modifier_because_it_overrides_a_member_in_the_base_class_0; + error(errorNode, diag, baseClassName); + } + return MemberOverrideStatus.NeedsOverride; + } + else if (memberHasAbstractModifier && baseHasAbstract) { + if (errorNode) { + error(errorNode, Diagnostics.This_member_must_have_an_override_modifier_because_it_overrides_an_abstract_method_that_is_declared_in_the_base_class_0, baseClassName); + } + return MemberOverrideStatus.NeedsOverride; + } + } + } + else if (memberHasOverrideModifier) { + if (errorNode) { + const className = typeToString(type); + error( + errorNode, + isJs ? + Diagnostics.This_member_cannot_have_a_JSDoc_comment_with_an_override_tag_because_its_containing_class_0_does_not_extend_another_class : + Diagnostics.This_member_cannot_have_an_override_modifier_because_its_containing_class_0_does_not_extend_another_class, + className, + ); + } + return MemberOverrideStatus.HasInvalidOverride; + } + + return MemberOverrideStatus.Ok; + } + + function issueMemberSpecificError(node: ClassLikeDeclaration, typeWithThis: Type, baseWithThis: Type, broadDiag: DiagnosticMessage) { + // iterate over all implemented properties and issue errors on each one which isn't compatible, rather than the class as a whole, if possible + let issuedMemberError = false; + for (const member of node.members) { + if (isStatic(member)) { + continue; + } + const declaredProp = member.name && getSymbolAtLocation(member.name) || getSymbolAtLocation(member); + if (declaredProp) { + const prop = getPropertyOfType(typeWithThis, declaredProp.escapedName); + const baseProp = getPropertyOfType(baseWithThis, declaredProp.escapedName); + if (prop && baseProp) { + const rootChain = () => + chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.Property_0_in_type_1_is_not_assignable_to_the_same_property_in_base_type_2, + symbolToString(declaredProp), + typeToString(typeWithThis), + typeToString(baseWithThis), + ); + if (!checkTypeAssignableTo(getTypeOfSymbol(prop), getTypeOfSymbol(baseProp), member.name || member, /*headMessage*/ undefined, rootChain)) { + issuedMemberError = true; + } + } + } + } + if (!issuedMemberError) { + // check again with diagnostics to generate a less-specific error + checkTypeAssignableTo(typeWithThis, baseWithThis, node.name || node, broadDiag); + } + } + + function checkBaseTypeAccessibility(type: Type, node: ExpressionWithTypeArguments) { + const signatures = getSignaturesOfType(type, SignatureKind.Construct); + if (signatures.length) { + const declaration = signatures[0].declaration; + if (declaration && hasEffectiveModifier(declaration, ModifierFlags.Private)) { + const typeClassDeclaration = getClassLikeDeclarationOfSymbol(type.symbol)!; + if (!isNodeWithinClass(node, typeClassDeclaration)) { + error(node, Diagnostics.Cannot_extend_a_class_0_Class_constructor_is_marked_as_private, getFullyQualifiedName(type.symbol)); + } + } + } + } + + /** + * Checks a member declaration node to see if has a missing or invalid `override` modifier. + * @param node Class-like node where the member is declared. + * @param member Member declaration node. + * @param memberSymbol Member symbol. + * Note: `member` can be a synthetic node without a parent. + */ + function getMemberOverrideModifierStatus(node: ClassLikeDeclaration, member: ClassElement, memberSymbol: Symbol): MemberOverrideStatus { + if (!member.name) { + return MemberOverrideStatus.Ok; + } + + const classSymbol = getSymbolOfDeclaration(node); + const type = getDeclaredTypeOfSymbol(classSymbol) as InterfaceType; + const typeWithThis = getTypeWithThisArgument(type); + const staticType = getTypeOfSymbol(classSymbol) as ObjectType; + + const baseTypeNode = getEffectiveBaseTypeNode(node); + const baseTypes = baseTypeNode && getBaseTypes(type); + const baseWithThis = baseTypes?.length ? getTypeWithThisArgument(first(baseTypes), type.thisType) : undefined; + const baseStaticType = getBaseConstructorTypeOfClass(type); + + const memberHasOverrideModifier = member.parent + ? hasOverrideModifier(member) + : hasSyntacticModifier(member, ModifierFlags.Override); + + return checkMemberForOverrideModifier( + node, + staticType, + baseStaticType, + baseWithThis, + type, + typeWithThis, + memberHasOverrideModifier, + hasAbstractModifier(member), + isStatic(member), + /*memberIsParameterProperty*/ false, + memberSymbol, + ); + } + + function getTargetSymbol(s: Symbol) { + // if symbol is instantiated its flags are not copied from the 'target' + // so we'll need to get back original 'target' symbol to work with correct set of flags + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols have CheckFlags.Instantiated + return getCheckFlags(s) & CheckFlags.Instantiated ? (s as TransientSymbol).links.target! : s; + } + + function getClassOrInterfaceDeclarationsOfSymbol(symbol: Symbol) { + return filter(symbol.declarations, (d: Declaration): d is ClassDeclaration | InterfaceDeclaration => d.kind === SyntaxKind.ClassDeclaration || d.kind === SyntaxKind.InterfaceDeclaration); + } + + function checkKindsOfPropertyMemberOverrides(type: InterfaceType, baseType: BaseType): void { + // TypeScript 1.0 spec (April 2014): 8.2.3 + // A derived class inherits all members from its base class it doesn't override. + // Inheritance means that a derived class implicitly contains all non - overridden members of the base class. + // Both public and private property members are inherited, but only public property members can be overridden. + // A property member in a derived class is said to override a property member in a base class + // when the derived class property member has the same name and kind(instance or static) + // as the base class property member. + // The type of an overriding property member must be assignable(section 3.8.4) + // to the type of the overridden property member, or otherwise a compile - time error occurs. + // Base class instance member functions can be overridden by derived class instance member functions, + // but not by other kinds of members. + // Base class instance member variables and accessors can be overridden by + // derived class instance member variables and accessors, but not by other kinds of members. + + // NOTE: assignability is checked in checkClassDeclaration + const baseProperties = getPropertiesOfType(baseType); + + interface MemberInfo { + missedProperties: string[]; + baseTypeName: string; + typeName: string; + } + const notImplementedInfo = new Map(); + + basePropertyCheck: for (const baseProperty of baseProperties) { + const base = getTargetSymbol(baseProperty); + + if (base.flags & SymbolFlags.Prototype) { + continue; + } + const baseSymbol = getPropertyOfObjectType(type, base.escapedName); + if (!baseSymbol) { + continue; + } + const derived = getTargetSymbol(baseSymbol); + const baseDeclarationFlags = getDeclarationModifierFlagsFromSymbol(base); + + Debug.assert(!!derived, "derived should point to something, even if it is the base class' declaration."); + + // In order to resolve whether the inherited method was overridden in the base class or not, + // we compare the Symbols obtained. Since getTargetSymbol returns the symbol on the *uninstantiated* + // type declaration, derived and base resolve to the same symbol even in the case of generic classes. + if (derived === base) { + // derived class inherits base without override/redeclaration + const derivedClassDecl = getClassLikeDeclarationOfSymbol(type.symbol)!; + + // It is an error to inherit an abstract member without implementing it or being declared abstract. + // If there is no declaration for the derived class (as in the case of class expressions), + // then the class cannot be declared abstract. + if (baseDeclarationFlags & ModifierFlags.Abstract && (!derivedClassDecl || !hasSyntacticModifier(derivedClassDecl, ModifierFlags.Abstract))) { + // Searches other base types for a declaration that would satisfy the inherited abstract member. + // (The class may have more than one base type via declaration merging with an interface with the + // same name.) + for (const otherBaseType of getBaseTypes(type)) { + if (otherBaseType === baseType) continue; + const baseSymbol = getPropertyOfObjectType(otherBaseType, base.escapedName); + const derivedElsewhere = baseSymbol && getTargetSymbol(baseSymbol); + if (derivedElsewhere && derivedElsewhere !== base) { + continue basePropertyCheck; + } + } + const baseTypeName = typeToString(baseType); + const typeName = typeToString(type); + const basePropertyName = symbolToString(baseProperty); + const missedProperties = append(notImplementedInfo.get(derivedClassDecl)?.missedProperties, basePropertyName); + notImplementedInfo.set(derivedClassDecl, { baseTypeName, typeName, missedProperties }); + } + } + else { + // derived overrides base. + const derivedDeclarationFlags = getDeclarationModifierFlagsFromSymbol(derived); + if (baseDeclarationFlags & ModifierFlags.Private || derivedDeclarationFlags & ModifierFlags.Private) { + // either base or derived property is private - not override, skip it + continue; + } + + let errorMessage: DiagnosticMessage; + const basePropertyFlags = base.flags & SymbolFlags.PropertyOrAccessor; + const derivedPropertyFlags = derived.flags & SymbolFlags.PropertyOrAccessor; + if (basePropertyFlags && derivedPropertyFlags) { + // property/accessor is overridden with property/accessor + if ( + (getCheckFlags(base) & CheckFlags.Synthetic + ? base.declarations?.some(d => isPropertyAbstractOrInterface(d, baseDeclarationFlags)) + : base.declarations?.every(d => isPropertyAbstractOrInterface(d, baseDeclarationFlags))) + || getCheckFlags(base) & CheckFlags.Mapped + || derived.valueDeclaration && isBinaryExpression(derived.valueDeclaration) + ) { + // when the base property is abstract or from an interface, base/derived flags don't need to match + // for intersection properties, this must be true of *any* of the declarations, for others it must be true of *all* + // same when the derived property is from an assignment + continue; + } + + const overriddenInstanceProperty = basePropertyFlags !== SymbolFlags.Property && derivedPropertyFlags === SymbolFlags.Property; + const overriddenInstanceAccessor = basePropertyFlags === SymbolFlags.Property && derivedPropertyFlags !== SymbolFlags.Property; + if (overriddenInstanceProperty || overriddenInstanceAccessor) { + const errorMessage = overriddenInstanceProperty ? + Diagnostics._0_is_defined_as_an_accessor_in_class_1_but_is_overridden_here_in_2_as_an_instance_property : + Diagnostics._0_is_defined_as_a_property_in_class_1_but_is_overridden_here_in_2_as_an_accessor; + error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, symbolToString(base), typeToString(baseType), typeToString(type)); + } + else if (useDefineForClassFields) { + const uninitialized = derived.declarations?.find(d => d.kind === SyntaxKind.PropertyDeclaration && !(d as PropertyDeclaration).initializer); + if ( + uninitialized + && !(derived.flags & SymbolFlags.Transient) + && !(baseDeclarationFlags & ModifierFlags.Abstract) + && !(derivedDeclarationFlags & ModifierFlags.Abstract) + && !derived.declarations?.some(d => !!(d.flags & NodeFlags.Ambient)) + ) { + const constructor = findConstructorDeclaration(getClassLikeDeclarationOfSymbol(type.symbol)!); + const propName = (uninitialized as PropertyDeclaration).name; + if ( + (uninitialized as PropertyDeclaration).exclamationToken + || !constructor + || !isIdentifier(propName) + || !strictNullChecks + || !isPropertyInitializedInConstructor(propName, type, constructor) + ) { + const errorMessage = Diagnostics.Property_0_will_overwrite_the_base_property_in_1_If_this_is_intentional_add_an_initializer_Otherwise_add_a_declare_modifier_or_remove_the_redundant_declaration; + error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, symbolToString(base), typeToString(baseType)); + } + } + } + + // correct case + continue; + } + else if (isPrototypeProperty(base)) { + if (isPrototypeProperty(derived) || derived.flags & SymbolFlags.Property) { + // method is overridden with method or property -- correct case + continue; + } + else { + Debug.assert(!!(derived.flags & SymbolFlags.Accessor)); + errorMessage = Diagnostics.Class_0_defines_instance_member_function_1_but_extended_class_2_defines_it_as_instance_member_accessor; + } + } + else if (base.flags & SymbolFlags.Accessor) { + errorMessage = Diagnostics.Class_0_defines_instance_member_accessor_1_but_extended_class_2_defines_it_as_instance_member_function; + } + else { + errorMessage = Diagnostics.Class_0_defines_instance_member_property_1_but_extended_class_2_defines_it_as_instance_member_function; + } + + error(getNameOfDeclaration(derived.valueDeclaration) || derived.valueDeclaration, errorMessage, typeToString(baseType), symbolToString(base), typeToString(type)); + } + } + + for (const [errorNode, memberInfo] of notImplementedInfo) { + if (length(memberInfo.missedProperties) === 1) { + if (isClassExpression(errorNode)) { + error(errorNode, Diagnostics.Non_abstract_class_expression_does_not_implement_inherited_abstract_member_0_from_class_1, first(memberInfo.missedProperties), memberInfo.baseTypeName); + } + else { + error(errorNode, Diagnostics.Non_abstract_class_0_does_not_implement_inherited_abstract_member_1_from_class_2, memberInfo.typeName, first(memberInfo.missedProperties), memberInfo.baseTypeName); + } + } + else if (length(memberInfo.missedProperties) > 5) { + const missedProperties = map(memberInfo.missedProperties.slice(0, 4), prop => `'${prop}'`).join(", "); + const remainingMissedProperties = length(memberInfo.missedProperties) - 4; + if (isClassExpression(errorNode)) { + error(errorNode, Diagnostics.Non_abstract_class_expression_is_missing_implementations_for_the_following_members_of_0_Colon_1_and_2_more, memberInfo.baseTypeName, missedProperties, remainingMissedProperties); + } + else { + error(errorNode, Diagnostics.Non_abstract_class_0_is_missing_implementations_for_the_following_members_of_1_Colon_2_and_3_more, memberInfo.typeName, memberInfo.baseTypeName, missedProperties, remainingMissedProperties); + } + } + else { + const missedProperties = map(memberInfo.missedProperties, prop => `'${prop}'`).join(", "); + if (isClassExpression(errorNode)) { + error(errorNode, Diagnostics.Non_abstract_class_expression_is_missing_implementations_for_the_following_members_of_0_Colon_1, memberInfo.baseTypeName, missedProperties); + } + else { + error(errorNode, Diagnostics.Non_abstract_class_0_is_missing_implementations_for_the_following_members_of_1_Colon_2, memberInfo.typeName, memberInfo.baseTypeName, missedProperties); + } + } + } + } + + function isPropertyAbstractOrInterface(declaration: Declaration, baseDeclarationFlags: ModifierFlags) { + return baseDeclarationFlags & ModifierFlags.Abstract && (!isPropertyDeclaration(declaration) || !declaration.initializer) + || isInterfaceDeclaration(declaration.parent); + } + + function getNonInheritedProperties(type: InterfaceType, baseTypes: BaseType[], properties: Symbol[]) { + if (!length(baseTypes)) { + return properties; + } + const seen = new Map<__String, Symbol>(); + forEach(properties, p => { + seen.set(p.escapedName, p); + }); + + for (const base of baseTypes) { + const properties = getPropertiesOfType(getTypeWithThisArgument(base, type.thisType)); + for (const prop of properties) { + const existing = seen.get(prop.escapedName); + if (existing && prop.parent === existing.parent) { + seen.delete(prop.escapedName); + } + } + } + + return arrayFrom(seen.values()); + } + + function checkInheritedPropertiesAreIdentical(type: InterfaceType, typeNode: Node): boolean { + const baseTypes = getBaseTypes(type); + if (baseTypes.length < 2) { + return true; + } + + interface InheritanceInfoMap { + prop: Symbol; + containingType: Type; + } + const seen = new Map<__String, InheritanceInfoMap>(); + forEach(resolveDeclaredMembers(type).declaredProperties, p => { + seen.set(p.escapedName, { prop: p, containingType: type }); + }); + let ok = true; + + for (const base of baseTypes) { + const properties = getPropertiesOfType(getTypeWithThisArgument(base, type.thisType)); + for (const prop of properties) { + const existing = seen.get(prop.escapedName); + if (!existing) { + seen.set(prop.escapedName, { prop, containingType: base }); + } + else { + const isInheritedProperty = existing.containingType !== type; + if (isInheritedProperty && !isPropertyIdenticalTo(existing.prop, prop)) { + ok = false; + + const typeName1 = typeToString(existing.containingType); + const typeName2 = typeToString(base); + + let errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Named_property_0_of_types_1_and_2_are_not_identical, symbolToString(prop), typeName1, typeName2); + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Interface_0_cannot_simultaneously_extend_types_1_and_2, typeToString(type), typeName1, typeName2); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(typeNode), typeNode, errorInfo)); + } + } + } + } + + return ok; + } + + function checkPropertyInitialization(node: ClassLikeDeclaration) { + if (!strictNullChecks || !strictPropertyInitialization || node.flags & NodeFlags.Ambient) { + return; + } + const constructor = findConstructorDeclaration(node); + for (const member of node.members) { + if (getEffectiveModifierFlags(member) & ModifierFlags.Ambient) { + continue; + } + if (!isStatic(member) && isPropertyWithoutInitializer(member)) { + const propName = (member as PropertyDeclaration).name; + if (isIdentifier(propName) || isPrivateIdentifier(propName) || isComputedPropertyName(propName)) { + const type = getTypeOfSymbol(getSymbolOfDeclaration(member)); + if (!(type.flags & TypeFlags.AnyOrUnknown || containsUndefinedType(type))) { + if (!constructor || !isPropertyInitializedInConstructor(propName, type, constructor)) { + error(member.name, Diagnostics.Property_0_has_no_initializer_and_is_not_definitely_assigned_in_the_constructor, declarationNameToString(propName)); + } + } + } + } + } + } + + function isPropertyWithoutInitializer(node: Node) { + return node.kind === SyntaxKind.PropertyDeclaration && + !hasAbstractModifier(node) && + !(node as PropertyDeclaration).exclamationToken && + !(node as PropertyDeclaration).initializer; + } + + function isPropertyInitializedInStaticBlocks(propName: Identifier | PrivateIdentifier, propType: Type, staticBlocks: readonly ClassStaticBlockDeclaration[], startPos: number, endPos: number) { + for (const staticBlock of staticBlocks) { + // static block must be within the provided range as they are evaluated in document order (unlike constructors) + if (staticBlock.pos >= startPos && staticBlock.pos <= endPos) { + const reference = factory.createPropertyAccessExpression(factory.createThis(), propName); + setParent(reference.expression, reference); + setParent(reference, staticBlock); + reference.flowNode = staticBlock.returnFlowNode; + const flowType = getFlowTypeOfReference(reference, propType, getOptionalType(propType)); + if (!containsUndefinedType(flowType)) { + return true; + } + } + } + return false; + } + + function isPropertyInitializedInConstructor(propName: Identifier | PrivateIdentifier | ComputedPropertyName, propType: Type, constructor: ConstructorDeclaration) { + const reference = isComputedPropertyName(propName) + ? factory.createElementAccessExpression(factory.createThis(), propName.expression) + : factory.createPropertyAccessExpression(factory.createThis(), propName); + setParent(reference.expression, reference); + setParent(reference, constructor); + reference.flowNode = constructor.returnFlowNode; + const flowType = getFlowTypeOfReference(reference, propType, getOptionalType(propType)); + return !containsUndefinedType(flowType); + } + + function checkInterfaceDeclaration(node: InterfaceDeclaration) { + // Grammar checking + if (!checkGrammarModifiers(node)) checkGrammarInterfaceDeclaration(node); + + checkTypeParameters(node.typeParameters); + addLazyDiagnostic(() => { + checkTypeNameIsReserved(node.name, Diagnostics.Interface_name_cannot_be_0); + + checkExportsOnMergedDeclarations(node); + const symbol = getSymbolOfDeclaration(node); + checkTypeParameterListsIdentical(symbol); + + // Only check this symbol once + const firstInterfaceDecl = getDeclarationOfKind(symbol, SyntaxKind.InterfaceDeclaration); + if (node === firstInterfaceDecl) { + const type = getDeclaredTypeOfSymbol(symbol) as InterfaceType; + const typeWithThis = getTypeWithThisArgument(type); + // run subsequent checks only if first set succeeded + if (checkInheritedPropertiesAreIdentical(type, node.name)) { + for (const baseType of getBaseTypes(type)) { + checkTypeAssignableTo(typeWithThis, getTypeWithThisArgument(baseType, type.thisType), node.name, Diagnostics.Interface_0_incorrectly_extends_interface_1); + } + checkIndexConstraints(type, symbol); + } + } + checkObjectTypeForDuplicateDeclarations(node); + }); + forEach(getInterfaceBaseTypeNodes(node), heritageElement => { + if (!isEntityNameExpression(heritageElement.expression) || isOptionalChain(heritageElement.expression)) { + error(heritageElement.expression, Diagnostics.An_interface_can_only_extend_an_identifier_Slashqualified_name_with_optional_type_arguments); + } + checkTypeReferenceNode(heritageElement); + }); + + forEach(node.members, checkSourceElement); + + addLazyDiagnostic(() => { + checkTypeForDuplicateIndexSignatures(node); + registerForUnusedIdentifiersCheck(node); + }); + } + + function checkTypeAliasDeclaration(node: TypeAliasDeclaration) { + // Grammar checking + checkGrammarModifiers(node); + checkTypeNameIsReserved(node.name, Diagnostics.Type_alias_name_cannot_be_0); + checkExportsOnMergedDeclarations(node); + checkTypeParameters(node.typeParameters); + if (node.type.kind === SyntaxKind.IntrinsicKeyword) { + if (!intrinsicTypeKinds.has(node.name.escapedText as string) || length(node.typeParameters) !== 1) { + error(node.type, Diagnostics.The_intrinsic_keyword_can_only_be_used_to_declare_compiler_provided_intrinsic_types); + } + } + else { + checkSourceElement(node.type); + registerForUnusedIdentifiersCheck(node); + } + } + + function computeEnumMemberValues(node: EnumDeclaration) { + const nodeLinks = getNodeLinks(node); + if (!(nodeLinks.flags & NodeCheckFlags.EnumValuesComputed)) { + nodeLinks.flags |= NodeCheckFlags.EnumValuesComputed; + let autoValue: number | undefined = 0; + let previous: EnumMember | undefined; + for (const member of node.members) { + const result = computeEnumMemberValue(member, autoValue, previous); + getNodeLinks(member).enumMemberValue = result; + autoValue = typeof result.value === "number" ? result.value + 1 : undefined; + previous = member; + } + } + } + + function computeEnumMemberValue(member: EnumMember, autoValue: number | undefined, previous: EnumMember | undefined): EvaluatorResult { + if (isComputedNonLiteralName(member.name)) { + error(member.name, Diagnostics.Computed_property_names_are_not_allowed_in_enums); + } + else { + const text = getTextOfPropertyName(member.name); + if (isNumericLiteralName(text) && !isInfinityOrNaNString(text)) { + error(member.name, Diagnostics.An_enum_member_cannot_have_a_numeric_name); + } + } + if (member.initializer) { + return computeConstantEnumMemberValue(member); + } + // In ambient non-const numeric enum declarations, enum members without initializers are + // considered computed members (as opposed to having auto-incremented values). + if (member.parent.flags & NodeFlags.Ambient && !isEnumConst(member.parent)) { + return evaluatorResult(/*value*/ undefined); + } + // If the member declaration specifies no value, the member is considered a constant enum member. + // If the member is the first member in the enum declaration, it is assigned the value zero. + // Otherwise, it is assigned the value of the immediately preceding member plus one, and an error + // occurs if the immediately preceding member is not a constant enum member. + if (autoValue === undefined) { + error(member.name, Diagnostics.Enum_member_must_have_initializer); + return evaluatorResult(/*value*/ undefined); + } + if (getIsolatedModules(compilerOptions) && previous?.initializer) { + const prevValue = getEnumMemberValue(previous); + if (!(typeof prevValue.value === "number" && !prevValue.resolvedOtherFiles)) { + error( + member.name, + Diagnostics.Enum_member_following_a_non_literal_numeric_member_must_have_an_initializer_when_isolatedModules_is_enabled, + ); + } + } + return evaluatorResult(autoValue); + } + + function computeConstantEnumMemberValue(member: EnumMember): EvaluatorResult { + const isConstEnum = isEnumConst(member.parent); + const initializer = member.initializer!; + const result = evaluate(initializer, member); + if (result.value !== undefined) { + if (isConstEnum && typeof result.value === "number" && !isFinite(result.value)) { + error( + initializer, + isNaN(result.value) ? + Diagnostics.const_enum_member_initializer_was_evaluated_to_disallowed_value_NaN : + Diagnostics.const_enum_member_initializer_was_evaluated_to_a_non_finite_value, + ); + } + else if (getIsolatedModules(compilerOptions) && typeof result.value === "string" && !result.isSyntacticallyString) { + error( + initializer, + Diagnostics._0_has_a_string_type_but_must_have_syntactically_recognizable_string_syntax_when_isolatedModules_is_enabled, + `${idText(member.parent.name)}.${getTextOfPropertyName(member.name)}`, + ); + } + } + else if (isConstEnum) { + error(initializer, Diagnostics.const_enum_member_initializers_must_be_constant_expressions); + } + else if (member.parent.flags & NodeFlags.Ambient) { + error(initializer, Diagnostics.In_ambient_enum_declarations_member_initializer_must_be_constant_expression); + } + else { + checkTypeAssignableTo(checkExpression(initializer), numberType, initializer, Diagnostics.Type_0_is_not_assignable_to_type_1_as_required_for_computed_enum_member_values); + } + return result; + } + + function evaluateEntityNameExpression(expr: EntityNameExpression, location?: Declaration) { + const symbol = resolveEntityName(expr, SymbolFlags.Value, /*ignoreErrors*/ true); + if (!symbol) return evaluatorResult(/*value*/ undefined); + + if (expr.kind === SyntaxKind.Identifier) { + const identifier = expr; + if (isInfinityOrNaNString(identifier.escapedText) && (symbol === getGlobalSymbol(identifier.escapedText, SymbolFlags.Value, /*diagnostic*/ undefined))) { + // Technically we resolved a global lib file here, but the decision to treat this as numeric + // is more predicated on the fact that the single-file resolution *didn't* resolve to a + // different meaning of `Infinity` or `NaN`. Transpilers handle this no problem. + return evaluatorResult(+(identifier.escapedText), /*isSyntacticallyString*/ false); + } + } + + if (symbol.flags & SymbolFlags.EnumMember) { + return location ? evaluateEnumMember(expr, symbol, location) : getEnumMemberValue(symbol.valueDeclaration as EnumMember); + } + if (isConstantVariable(symbol)) { + const declaration = symbol.valueDeclaration; + if (declaration && isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && (!location || declaration !== location && isBlockScopedNameDeclaredBeforeUse(declaration, location))) { + const result = evaluate(declaration.initializer, declaration); + if (location && getSourceFileOfNode(location) !== getSourceFileOfNode(declaration)) { + return evaluatorResult( + result.value, + /*isSyntacticallyString*/ false, + /*resolvedOtherFiles*/ true, + /*hasExternalReferences*/ true, + ); + } + return evaluatorResult(result.value, result.isSyntacticallyString, result.resolvedOtherFiles, /*hasExternalReferences*/ true); + } + } + return evaluatorResult(/*value*/ undefined); + } + + function evaluateElementAccessExpression(expr: ElementAccessExpression, location?: Declaration) { + const root = expr.expression; + if (isEntityNameExpression(root) && isStringLiteralLike(expr.argumentExpression)) { + const rootSymbol = resolveEntityName(root, SymbolFlags.Value, /*ignoreErrors*/ true); + if (rootSymbol && rootSymbol.flags & SymbolFlags.Enum) { + const name = escapeLeadingUnderscores(expr.argumentExpression.text); + const member = rootSymbol.exports!.get(name); + if (member) { + Debug.assert(getSourceFileOfNode(member.valueDeclaration) === getSourceFileOfNode(rootSymbol.valueDeclaration)); + return location ? evaluateEnumMember(expr, member, location) : getEnumMemberValue(member.valueDeclaration as EnumMember); + } + } + } + return evaluatorResult(/*value*/ undefined); + } + + function evaluateEnumMember(expr: Expression, symbol: Symbol, location: Declaration) { + const declaration = symbol.valueDeclaration; + if (!declaration || declaration === location) { + error(expr, Diagnostics.Property_0_is_used_before_being_assigned, symbolToString(symbol)); + return evaluatorResult(/*value*/ undefined); + } + if (!isBlockScopedNameDeclaredBeforeUse(declaration, location)) { + error(expr, Diagnostics.A_member_initializer_in_a_enum_declaration_cannot_reference_members_declared_after_it_including_members_defined_in_other_enums); + return evaluatorResult(/*value*/ 0); + } + const value = getEnumMemberValue(declaration as EnumMember); + if (location.parent !== declaration.parent) { + return evaluatorResult(value.value, value.isSyntacticallyString, value.resolvedOtherFiles, /*hasExternalReferences*/ true); + } + return value; + } + + function checkEnumDeclaration(node: EnumDeclaration) { + addLazyDiagnostic(() => checkEnumDeclarationWorker(node)); + } + + function checkEnumDeclarationWorker(node: EnumDeclaration) { + // Grammar checking + checkGrammarModifiers(node); + + checkCollisionsForDeclarationName(node, node.name); + checkExportsOnMergedDeclarations(node); + node.members.forEach(checkEnumMember); + + computeEnumMemberValues(node); + + // Spec 2014 - Section 9.3: + // It isn't possible for one enum declaration to continue the automatic numbering sequence of another, + // and when an enum type has multiple declarations, only one declaration is permitted to omit a value + // for the first member. + // + // Only perform this check once per symbol + const enumSymbol = getSymbolOfDeclaration(node); + const firstDeclaration = getDeclarationOfKind(enumSymbol, node.kind); + if (node === firstDeclaration) { + if (enumSymbol.declarations && enumSymbol.declarations.length > 1) { + const enumIsConst = isEnumConst(node); + // check that const is placed\omitted on all enum declarations + forEach(enumSymbol.declarations, decl => { + if (isEnumDeclaration(decl) && isEnumConst(decl) !== enumIsConst) { + error(getNameOfDeclaration(decl), Diagnostics.Enum_declarations_must_all_be_const_or_non_const); + } + }); + } + + let seenEnumMissingInitialInitializer = false; + forEach(enumSymbol.declarations, declaration => { + // return true if we hit a violation of the rule, false otherwise + if (declaration.kind !== SyntaxKind.EnumDeclaration) { + return false; + } + + const enumDeclaration = declaration as EnumDeclaration; + if (!enumDeclaration.members.length) { + return false; + } + + const firstEnumMember = enumDeclaration.members[0]; + if (!firstEnumMember.initializer) { + if (seenEnumMissingInitialInitializer) { + error(firstEnumMember.name, Diagnostics.In_an_enum_with_multiple_declarations_only_one_declaration_can_omit_an_initializer_for_its_first_enum_element); + } + else { + seenEnumMissingInitialInitializer = true; + } + } + }); + } + } + + function checkEnumMember(node: EnumMember) { + if (isPrivateIdentifier(node.name)) { + error(node, Diagnostics.An_enum_member_cannot_be_named_with_a_private_identifier); + } + if (node.initializer) { + checkExpression(node.initializer); + } + } + + function getFirstNonAmbientClassOrFunctionDeclaration(symbol: Symbol): Declaration | undefined { + const declarations = symbol.declarations; + if (declarations) { + for (const declaration of declarations) { + if ( + (declaration.kind === SyntaxKind.ClassDeclaration || + (declaration.kind === SyntaxKind.FunctionDeclaration && nodeIsPresent((declaration as FunctionLikeDeclaration).body))) && + !(declaration.flags & NodeFlags.Ambient) + ) { + return declaration; + } + } + } + return undefined; + } + + function inSameLexicalScope(node1: Node, node2: Node) { + const container1 = getEnclosingBlockScopeContainer(node1); + const container2 = getEnclosingBlockScopeContainer(node2); + if (isGlobalSourceFile(container1)) { + return isGlobalSourceFile(container2); + } + else if (isGlobalSourceFile(container2)) { + return false; + } + else { + return container1 === container2; + } + } + + function checkModuleDeclaration(node: ModuleDeclaration) { + if (node.body) { + checkSourceElement(node.body); + if (!isGlobalScopeAugmentation(node)) { + registerForUnusedIdentifiersCheck(node); + } + } + + addLazyDiagnostic(checkModuleDeclarationDiagnostics); + + function checkModuleDeclarationDiagnostics() { + // Grammar checking + const isGlobalAugmentation = isGlobalScopeAugmentation(node); + const inAmbientContext = node.flags & NodeFlags.Ambient; + if (isGlobalAugmentation && !inAmbientContext) { + error(node.name, Diagnostics.Augmentations_for_the_global_scope_should_have_declare_modifier_unless_they_appear_in_already_ambient_context); + } + + const isAmbientExternalModule: boolean = isAmbientModule(node); + const contextErrorMessage = isAmbientExternalModule + ? Diagnostics.An_ambient_module_declaration_is_only_allowed_at_the_top_level_in_a_file + : Diagnostics.A_namespace_declaration_is_only_allowed_at_the_top_level_of_a_namespace_or_module; + if (checkGrammarModuleElementContext(node, contextErrorMessage)) { + // If we hit a module declaration in an illegal context, just bail out to avoid cascading errors. + return; + } + + if (!checkGrammarModifiers(node)) { + if (!inAmbientContext && node.name.kind === SyntaxKind.StringLiteral) { + grammarErrorOnNode(node.name, Diagnostics.Only_ambient_modules_can_use_quoted_names); + } + } + + if (isIdentifier(node.name)) { + checkCollisionsForDeclarationName(node, node.name); + } + + checkExportsOnMergedDeclarations(node); + const symbol = getSymbolOfDeclaration(node); + + // The following checks only apply on a non-ambient instantiated module declaration. + if ( + symbol.flags & SymbolFlags.ValueModule + && !inAmbientContext + && isInstantiatedModule(node, shouldPreserveConstEnums(compilerOptions)) + ) { + if (getIsolatedModules(compilerOptions) && !getSourceFileOfNode(node).externalModuleIndicator) { + // This could be loosened a little if needed. The only problem we are trying to avoid is unqualified + // references to namespace members declared in other files. But use of namespaces is discouraged anyway, + // so for now we will just not allow them in scripts, which is the only place they can merge cross-file. + error(node.name, Diagnostics.Namespaces_are_not_allowed_in_global_script_files_when_0_is_enabled_If_this_file_is_not_intended_to_be_a_global_script_set_moduleDetection_to_force_or_add_an_empty_export_statement, isolatedModulesLikeFlagName); + } + if (symbol.declarations?.length! > 1) { + const firstNonAmbientClassOrFunc = getFirstNonAmbientClassOrFunctionDeclaration(symbol); + if (firstNonAmbientClassOrFunc) { + if (getSourceFileOfNode(node) !== getSourceFileOfNode(firstNonAmbientClassOrFunc)) { + error(node.name, Diagnostics.A_namespace_declaration_cannot_be_in_a_different_file_from_a_class_or_function_with_which_it_is_merged); + } + else if (node.pos < firstNonAmbientClassOrFunc.pos) { + error(node.name, Diagnostics.A_namespace_declaration_cannot_be_located_prior_to_a_class_or_function_with_which_it_is_merged); + } + } + + // if the module merges with a class declaration in the same lexical scope, + // we need to track this to ensure the correct emit. + const mergedClass = getDeclarationOfKind(symbol, SyntaxKind.ClassDeclaration); + if ( + mergedClass && + inSameLexicalScope(node, mergedClass) + ) { + getNodeLinks(node).flags |= NodeCheckFlags.LexicalModuleMergesWithClass; + } + } + if ( + compilerOptions.verbatimModuleSyntax && + node.parent.kind === SyntaxKind.SourceFile && + (moduleKind === ModuleKind.CommonJS || node.parent.impliedNodeFormat === ModuleKind.CommonJS) + ) { + const exportModifier = node.modifiers?.find(m => m.kind === SyntaxKind.ExportKeyword); + if (exportModifier) { + error(exportModifier, Diagnostics.A_top_level_export_modifier_cannot_be_used_on_value_declarations_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + } + } + + if (isAmbientExternalModule) { + if (isExternalModuleAugmentation(node)) { + // body of the augmentation should be checked for consistency only if augmentation was applied to its target (either global scope or module) + // otherwise we'll be swamped in cascading errors. + // We can detect if augmentation was applied using following rules: + // - augmentation for a global scope is always applied + // - augmentation for some external module is applied if symbol for augmentation is merged (it was combined with target module). + const checkBody = isGlobalAugmentation || (getSymbolOfDeclaration(node).flags & SymbolFlags.Transient); + if (checkBody && node.body) { + for (const statement of node.body.statements) { + checkModuleAugmentationElement(statement, isGlobalAugmentation); + } + } + } + else if (isGlobalSourceFile(node.parent)) { + if (isGlobalAugmentation) { + error(node.name, Diagnostics.Augmentations_for_the_global_scope_can_only_be_directly_nested_in_external_modules_or_ambient_module_declarations); + } + else if (isExternalModuleNameRelative(getTextOfIdentifierOrLiteral(node.name))) { + error(node.name, Diagnostics.Ambient_module_declaration_cannot_specify_relative_module_name); + } + } + else { + if (isGlobalAugmentation) { + error(node.name, Diagnostics.Augmentations_for_the_global_scope_can_only_be_directly_nested_in_external_modules_or_ambient_module_declarations); + } + else { + // Node is not an augmentation and is not located on the script level. + // This means that this is declaration of ambient module that is located in other module or namespace which is prohibited. + error(node.name, Diagnostics.Ambient_modules_cannot_be_nested_in_other_modules_or_namespaces); + } + } + } + } + } + + function checkModuleAugmentationElement(node: Node, isGlobalAugmentation: boolean): void { + switch (node.kind) { + case SyntaxKind.VariableStatement: + // error each individual name in variable statement instead of marking the entire variable statement + for (const decl of (node as VariableStatement).declarationList.declarations) { + checkModuleAugmentationElement(decl, isGlobalAugmentation); + } + break; + case SyntaxKind.ExportAssignment: + case SyntaxKind.ExportDeclaration: + grammarErrorOnFirstToken(node, Diagnostics.Exports_and_export_assignments_are_not_permitted_in_module_augmentations); + break; + case SyntaxKind.ImportEqualsDeclaration: + case SyntaxKind.ImportDeclaration: + grammarErrorOnFirstToken(node, Diagnostics.Imports_are_not_permitted_in_module_augmentations_Consider_moving_them_to_the_enclosing_external_module); + break; + case SyntaxKind.BindingElement: + case SyntaxKind.VariableDeclaration: + const name = (node as VariableDeclaration | BindingElement).name; + if (isBindingPattern(name)) { + for (const el of name.elements) { + // mark individual names in binding pattern + checkModuleAugmentationElement(el, isGlobalAugmentation); + } + break; + } + // falls through + case SyntaxKind.ClassDeclaration: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.TypeAliasDeclaration: + if (isGlobalAugmentation) { + return; + } + break; + } + } + + function getFirstNonModuleExportsIdentifier(node: EntityNameOrEntityNameExpression): Identifier { + switch (node.kind) { + case SyntaxKind.Identifier: + return node; + case SyntaxKind.QualifiedName: + do { + node = node.left; + } + while (node.kind !== SyntaxKind.Identifier); + return node; + case SyntaxKind.PropertyAccessExpression: + do { + if (isModuleExportsAccessExpression(node.expression) && !isPrivateIdentifier(node.name)) { + return node.name; + } + node = node.expression; + } + while (node.kind !== SyntaxKind.Identifier); + return node; + } + } + + function checkExternalImportOrExportDeclaration(node: ImportDeclaration | ImportEqualsDeclaration | ExportDeclaration): boolean { + const moduleName = getExternalModuleName(node); + if (!moduleName || nodeIsMissing(moduleName)) { + // Should be a parse error. + return false; + } + if (!isStringLiteral(moduleName)) { + error(moduleName, Diagnostics.String_literal_expected); + return false; + } + const inAmbientExternalModule = node.parent.kind === SyntaxKind.ModuleBlock && isAmbientModule(node.parent.parent); + if (node.parent.kind !== SyntaxKind.SourceFile && !inAmbientExternalModule) { + error( + moduleName, + node.kind === SyntaxKind.ExportDeclaration ? + Diagnostics.Export_declarations_are_not_permitted_in_a_namespace : + Diagnostics.Import_declarations_in_a_namespace_cannot_reference_a_module, + ); + return false; + } + if (inAmbientExternalModule && isExternalModuleNameRelative(moduleName.text)) { + // we have already reported errors on top level imports/exports in external module augmentations in checkModuleDeclaration + // no need to do this again. + if (!isTopLevelInExternalModuleAugmentation(node)) { + // TypeScript 1.0 spec (April 2013): 12.1.6 + // An ExternalImportDeclaration in an AmbientExternalModuleDeclaration may reference + // other external modules only through top - level external module names. + // Relative external module names are not permitted. + error(node, Diagnostics.Import_or_export_declaration_in_an_ambient_module_declaration_cannot_reference_module_through_relative_module_name); + return false; + } + } + if (!isImportEqualsDeclaration(node) && node.attributes) { + const diagnostic = node.attributes.token === SyntaxKind.WithKeyword ? Diagnostics.Import_attribute_values_must_be_string_literal_expressions : Diagnostics.Import_assertion_values_must_be_string_literal_expressions; + let hasError = false; + for (const attr of node.attributes.elements) { + if (!isStringLiteral(attr.value)) { + hasError = true; + error(attr.value, diagnostic); + } + } + return !hasError; + } + return true; + } + + function checkModuleExportName(name: ModuleExportName | undefined, allowStringLiteral = true) { + if (name === undefined || name.kind !== SyntaxKind.StringLiteral) { + return; + } + if (!allowStringLiteral) { + grammarErrorOnNode(name, Diagnostics.Identifier_expected); + } + else if (moduleKind === ModuleKind.ES2015 || moduleKind === ModuleKind.ES2020) { + grammarErrorOnNode(name, Diagnostics.String_literal_import_and_export_names_are_not_supported_when_the_module_flag_is_set_to_es2015_or_es2020); + } + } + + function checkAliasSymbol(node: AliasDeclarationNode) { + let symbol = getSymbolOfDeclaration(node); + const target = resolveAlias(symbol); + + if (target !== unknownSymbol) { + // For external modules, `symbol` represents the local symbol for an alias. + // This local symbol will merge any other local declarations (excluding other aliases) + // and symbol.flags will contains combined representation for all merged declaration. + // Based on symbol.flags we can compute a set of excluded meanings (meaning that resolved alias should not have, + // otherwise it will conflict with some local declaration). Note that in addition to normal flags we include matching SymbolFlags.Export* + // in order to prevent collisions with declarations that were exported from the current module (they still contribute to local names). + symbol = getMergedSymbol(symbol.exportSymbol || symbol); + + // A type-only import/export will already have a grammar error in a JS file, so no need to issue more errors within + if (isInJSFile(node) && !(target.flags & SymbolFlags.Value) && !isTypeOnlyImportOrExportDeclaration(node)) { + const errorNode = isImportOrExportSpecifier(node) ? node.propertyName || node.name : + isNamedDeclaration(node) ? node.name : + node; + + Debug.assert(node.kind !== SyntaxKind.NamespaceExport); + if (node.kind === SyntaxKind.ExportSpecifier) { + const diag = error(errorNode, Diagnostics.Types_cannot_appear_in_export_declarations_in_JavaScript_files); + const alreadyExportedSymbol = getSourceFileOfNode(node).symbol?.exports?.get(moduleExportNameTextEscaped(node.propertyName || node.name)); + if (alreadyExportedSymbol === target) { + const exportingDeclaration = alreadyExportedSymbol.declarations?.find(isJSDocNode); + if (exportingDeclaration) { + addRelatedInfo( + diag, + createDiagnosticForNode( + exportingDeclaration, + Diagnostics._0_is_automatically_exported_here, + unescapeLeadingUnderscores(alreadyExportedSymbol.escapedName), + ), + ); + } + } + } + else { + Debug.assert(node.kind !== SyntaxKind.VariableDeclaration); + const importDeclaration = findAncestor(node, or(isImportDeclaration, isImportEqualsDeclaration)); + const moduleSpecifier = (importDeclaration && tryGetModuleSpecifierFromDeclaration(importDeclaration)?.text) ?? "..."; + const importedIdentifier = unescapeLeadingUnderscores(isIdentifier(errorNode) ? errorNode.escapedText : symbol.escapedName); + error( + errorNode, + Diagnostics._0_is_a_type_and_cannot_be_imported_in_JavaScript_files_Use_1_in_a_JSDoc_type_annotation, + importedIdentifier, + `import("${moduleSpecifier}").${importedIdentifier}`, + ); + } + return; + } + + const targetFlags = getSymbolFlags(target); + const excludedMeanings = (symbol.flags & (SymbolFlags.Value | SymbolFlags.ExportValue) ? SymbolFlags.Value : 0) | + (symbol.flags & SymbolFlags.Type ? SymbolFlags.Type : 0) | + (symbol.flags & SymbolFlags.Namespace ? SymbolFlags.Namespace : 0); + if (targetFlags & excludedMeanings) { + const message = node.kind === SyntaxKind.ExportSpecifier ? + Diagnostics.Export_declaration_conflicts_with_exported_declaration_of_0 : + Diagnostics.Import_declaration_conflicts_with_local_declaration_of_0; + error(node, message, symbolToString(symbol)); + } + else if (node.kind !== SyntaxKind.ExportSpecifier) { + // Look at 'compilerOptions.isolatedModules' and not 'getIsolatedModules(...)' (which considers 'verbatimModuleSyntax') + // here because 'verbatimModuleSyntax' will already have an error for importing a type without 'import type'. + const appearsValueyToTranspiler = compilerOptions.isolatedModules && !findAncestor(node, isTypeOnlyImportOrExportDeclaration); + if (appearsValueyToTranspiler && symbol.flags & (SymbolFlags.Value | SymbolFlags.ExportValue)) { + error( + node, + Diagnostics.Import_0_conflicts_with_local_value_so_must_be_declared_with_a_type_only_import_when_isolatedModules_is_enabled, + symbolToString(symbol), + isolatedModulesLikeFlagName, + ); + } + } + + if ( + getIsolatedModules(compilerOptions) + && !isTypeOnlyImportOrExportDeclaration(node) + && !(node.flags & NodeFlags.Ambient) + ) { + const typeOnlyAlias = getTypeOnlyAliasDeclaration(symbol); + const isType = !(targetFlags & SymbolFlags.Value); + if (isType || typeOnlyAlias) { + switch (node.kind) { + case SyntaxKind.ImportClause: + case SyntaxKind.ImportSpecifier: + case SyntaxKind.ImportEqualsDeclaration: { + if (compilerOptions.verbatimModuleSyntax) { + Debug.assertIsDefined(node.name, "An ImportClause with a symbol should have a name"); + const message = compilerOptions.verbatimModuleSyntax && isInternalModuleImportEqualsDeclaration(node) + ? Diagnostics.An_import_alias_cannot_resolve_to_a_type_or_type_only_declaration_when_verbatimModuleSyntax_is_enabled + : isType + ? Diagnostics._0_is_a_type_and_must_be_imported_using_a_type_only_import_when_verbatimModuleSyntax_is_enabled + : Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_imported_using_a_type_only_import_when_verbatimModuleSyntax_is_enabled; + const name = moduleExportNameTextUnescaped(node.kind === SyntaxKind.ImportSpecifier ? node.propertyName || node.name : node.name); + addTypeOnlyDeclarationRelatedInfo( + error(node, message, name), + isType ? undefined : typeOnlyAlias, + name, + ); + } + if (isType && node.kind === SyntaxKind.ImportEqualsDeclaration && hasEffectiveModifier(node, ModifierFlags.Export)) { + error(node, Diagnostics.Cannot_use_export_import_on_a_type_or_type_only_namespace_when_0_is_enabled, isolatedModulesLikeFlagName); + } + break; + } + case SyntaxKind.ExportSpecifier: { + // Don't allow re-exporting an export that will be elided when `--isolatedModules` is set. + // The exception is that `import type { A } from './a'; export { A }` is allowed + // because single-file analysis can determine that the export should be dropped. + if (compilerOptions.verbatimModuleSyntax || getSourceFileOfNode(typeOnlyAlias) !== getSourceFileOfNode(node)) { + const name = moduleExportNameTextUnescaped(node.propertyName || node.name); + const diagnostic = isType + ? error(node, Diagnostics.Re_exporting_a_type_when_0_is_enabled_requires_using_export_type, isolatedModulesLikeFlagName) + : error(node, Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_re_exported_using_a_type_only_re_export_when_1_is_enabled, name, isolatedModulesLikeFlagName); + addTypeOnlyDeclarationRelatedInfo(diagnostic, isType ? undefined : typeOnlyAlias, name); + break; + } + } + } + } + + if ( + compilerOptions.verbatimModuleSyntax && + node.kind !== SyntaxKind.ImportEqualsDeclaration && + !isInJSFile(node) && + (moduleKind === ModuleKind.CommonJS || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) + ) { + error(node, Diagnostics.ESM_syntax_is_not_allowed_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + } + + if (isImportSpecifier(node)) { + const targetSymbol = resolveAliasWithDeprecationCheck(symbol, node); + if (isDeprecatedSymbol(targetSymbol) && targetSymbol.declarations) { + addDeprecatedSuggestion(node, targetSymbol.declarations, targetSymbol.escapedName as string); + } + } + } + } + + function resolveAliasWithDeprecationCheck(symbol: Symbol, location: Node) { + if (!(symbol.flags & SymbolFlags.Alias) || isDeprecatedSymbol(symbol) || !getDeclarationOfAliasSymbol(symbol)) { + return symbol; + } + + const targetSymbol = resolveAlias(symbol); + if (targetSymbol === unknownSymbol) return targetSymbol; + + while (symbol.flags & SymbolFlags.Alias) { + const target = getImmediateAliasedSymbol(symbol); + if (target) { + if (target === targetSymbol) break; + if (target.declarations && length(target.declarations)) { + if (isDeprecatedSymbol(target)) { + addDeprecatedSuggestion(location, target.declarations, target.escapedName as string); + break; + } + else { + if (symbol === targetSymbol) break; + symbol = target; + } + } + } + else { + break; + } + } + return targetSymbol; + } + + function checkImportBinding(node: ImportEqualsDeclaration | ImportClause | NamespaceImport | ImportSpecifier) { + checkCollisionsForDeclarationName(node, node.name); + checkAliasSymbol(node); + if (node.kind === SyntaxKind.ImportSpecifier) { + checkModuleExportName(node.propertyName); + if ( + moduleExportNameIsDefault(node.propertyName || node.name) && + getESModuleInterop(compilerOptions) && + moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) + ) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportDefault); + } + } + } + + function checkImportAttributes(declaration: ImportDeclaration | ExportDeclaration | JSDocImportTag) { + const node = declaration.attributes; + if (node) { + const importAttributesType = getGlobalImportAttributesType(/*reportErrors*/ true); + if (importAttributesType !== emptyObjectType) { + checkTypeAssignableTo(getTypeFromImportAttributes(node), getNullableType(importAttributesType, TypeFlags.Undefined), node); + } + + const validForTypeAttributes = isExclusivelyTypeOnlyImportOrExport(declaration); + const override = getResolutionModeOverride(node, validForTypeAttributes ? grammarErrorOnNode : undefined); + const isImportAttributes = declaration.attributes.token === SyntaxKind.WithKeyword; + if (validForTypeAttributes && override) { + return; // Other grammar checks do not apply to type-only imports with resolution mode assertions + } + + const mode = (moduleKind === ModuleKind.NodeNext) && declaration.moduleSpecifier && getUsageModeForExpression(declaration.moduleSpecifier); + if (mode !== ModuleKind.ESNext && moduleKind !== ModuleKind.ESNext && moduleKind !== ModuleKind.Preserve) { + const message = isImportAttributes + ? moduleKind === ModuleKind.NodeNext + ? Diagnostics.Import_attributes_are_not_allowed_on_statements_that_compile_to_CommonJS_require_calls + : Diagnostics.Import_attributes_are_only_supported_when_the_module_option_is_set_to_esnext_nodenext_or_preserve + : moduleKind === ModuleKind.NodeNext + ? Diagnostics.Import_assertions_are_not_allowed_on_statements_that_compile_to_CommonJS_require_calls + : Diagnostics.Import_assertions_are_only_supported_when_the_module_option_is_set_to_esnext_nodenext_or_preserve; + return grammarErrorOnNode(node, message); + } + + const isTypeOnly = isJSDocImportTag(declaration) || (isImportDeclaration(declaration) ? declaration.importClause?.isTypeOnly : declaration.isTypeOnly); + if (isTypeOnly) { + return grammarErrorOnNode(node, isImportAttributes ? Diagnostics.Import_attributes_cannot_be_used_with_type_only_imports_or_exports : Diagnostics.Import_assertions_cannot_be_used_with_type_only_imports_or_exports); + } + + if (override) { + return grammarErrorOnNode(node, Diagnostics.resolution_mode_can_only_be_set_for_type_only_imports); + } + } + } + + function checkImportAttribute(node: ImportAttribute) { + return getRegularTypeOfLiteralType(checkExpressionCached(node.value)); + } + + function checkImportDeclaration(node: ImportDeclaration) { + if (checkGrammarModuleElementContext(node, isInJSFile(node) ? Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_module : Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_namespace_or_module)) { + // If we hit an import declaration in an illegal context, just bail out to avoid cascading errors. + return; + } + if (!checkGrammarModifiers(node) && node.modifiers) { + grammarErrorOnFirstToken(node, Diagnostics.An_import_declaration_cannot_have_modifiers); + } + if (checkExternalImportOrExportDeclaration(node)) { + const importClause = node.importClause; + if (importClause && !checkGrammarImportClause(importClause)) { + if (importClause.name) { + checkImportBinding(importClause); + } + if (importClause.namedBindings) { + if (importClause.namedBindings.kind === SyntaxKind.NamespaceImport) { + checkImportBinding(importClause.namedBindings); + if (moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) && getESModuleInterop(compilerOptions)) { + // import * as ns from "foo"; + checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportStar); + } + } + else { + const moduleExisted = resolveExternalModuleName(node, node.moduleSpecifier); + if (moduleExisted) { + forEach(importClause.namedBindings.elements, checkImportBinding); + } + } + } + } + } + checkImportAttributes(node); + } + + function checkImportEqualsDeclaration(node: ImportEqualsDeclaration) { + if (checkGrammarModuleElementContext(node, isInJSFile(node) ? Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_module : Diagnostics.An_import_declaration_can_only_be_used_at_the_top_level_of_a_namespace_or_module)) { + // If we hit an import declaration in an illegal context, just bail out to avoid cascading errors. + return; + } + + checkGrammarModifiers(node); + if (isInternalModuleImportEqualsDeclaration(node) || checkExternalImportOrExportDeclaration(node)) { + checkImportBinding(node); + markLinkedReferences(node, ReferenceHint.ExportImportEquals); + if (node.moduleReference.kind !== SyntaxKind.ExternalModuleReference) { + const target = resolveAlias(getSymbolOfDeclaration(node)); + if (target !== unknownSymbol) { + const targetFlags = getSymbolFlags(target); + if (targetFlags & SymbolFlags.Value) { + // Target is a value symbol, check that it is not hidden by a local declaration with the same name + const moduleName = getFirstIdentifier(node.moduleReference); + if (!(resolveEntityName(moduleName, SymbolFlags.Value | SymbolFlags.Namespace)!.flags & SymbolFlags.Namespace)) { + error(moduleName, Diagnostics.Module_0_is_hidden_by_a_local_declaration_with_the_same_name, declarationNameToString(moduleName)); + } + } + if (targetFlags & SymbolFlags.Type) { + checkTypeNameIsReserved(node.name, Diagnostics.Import_name_cannot_be_0); + } + } + if (node.isTypeOnly) { + grammarErrorOnNode(node, Diagnostics.An_import_alias_cannot_use_import_type); + } + } + else { + if (moduleKind >= ModuleKind.ES2015 && moduleKind !== ModuleKind.Preserve && getSourceFileOfNode(node).impliedNodeFormat === undefined && !node.isTypeOnly && !(node.flags & NodeFlags.Ambient)) { + // Import equals declaration is deprecated in es6 or above + grammarErrorOnNode(node, Diagnostics.Import_assignment_cannot_be_used_when_targeting_ECMAScript_modules_Consider_using_import_Asterisk_as_ns_from_mod_import_a_from_mod_import_d_from_mod_or_another_module_format_instead); + } + } + } + } + + function checkExportDeclaration(node: ExportDeclaration) { + if (checkGrammarModuleElementContext(node, isInJSFile(node) ? Diagnostics.An_export_declaration_can_only_be_used_at_the_top_level_of_a_module : Diagnostics.An_export_declaration_can_only_be_used_at_the_top_level_of_a_namespace_or_module)) { + // If we hit an export in an illegal context, just bail out to avoid cascading errors. + return; + } + + if (!checkGrammarModifiers(node) && hasSyntacticModifiers(node)) { + grammarErrorOnFirstToken(node, Diagnostics.An_export_declaration_cannot_have_modifiers); + } + + checkGrammarExportDeclaration(node); + if (!node.moduleSpecifier || checkExternalImportOrExportDeclaration(node)) { + if (node.exportClause && !isNamespaceExport(node.exportClause)) { + // export { x, y } + // export { x, y } from "foo" + forEach(node.exportClause.elements, checkExportSpecifier); + const inAmbientExternalModule = node.parent.kind === SyntaxKind.ModuleBlock && isAmbientModule(node.parent.parent); + const inAmbientNamespaceDeclaration = !inAmbientExternalModule && node.parent.kind === SyntaxKind.ModuleBlock && + !node.moduleSpecifier && node.flags & NodeFlags.Ambient; + if (node.parent.kind !== SyntaxKind.SourceFile && !inAmbientExternalModule && !inAmbientNamespaceDeclaration) { + error(node, Diagnostics.Export_declarations_are_not_permitted_in_a_namespace); + } + } + else { + // export * from "foo" + // export * as ns from "foo"; + const moduleSymbol = resolveExternalModuleName(node, node.moduleSpecifier!); + if (moduleSymbol && hasExportAssignmentSymbol(moduleSymbol)) { + error(node.moduleSpecifier, Diagnostics.Module_0_uses_export_and_cannot_be_used_with_export_Asterisk, symbolToString(moduleSymbol)); + } + else if (node.exportClause) { + checkAliasSymbol(node.exportClause); + checkModuleExportName(node.exportClause.name); + } + if (moduleKind !== ModuleKind.System && (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS)) { + if (node.exportClause) { + // export * as ns from "foo"; + // For ES2015 modules, we emit it as a pair of `import * as a_1 ...; export { a_1 as ns }` and don't need the helper. + // We only use the helper here when in esModuleInterop + if (getESModuleInterop(compilerOptions)) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportStar); + } + } + else { + // export * from "foo" + checkExternalEmitHelpers(node, ExternalEmitHelpers.ExportStar); + } + } + } + } + checkImportAttributes(node); + } + + function checkGrammarExportDeclaration(node: ExportDeclaration): boolean { + if (node.isTypeOnly && node.exportClause?.kind === SyntaxKind.NamedExports) { + return checkGrammarNamedImportsOrExports(node.exportClause); + } + return false; + } + + function checkGrammarModuleElementContext(node: Statement, errorMessage: DiagnosticMessage): boolean { + const isInAppropriateContext = node.parent.kind === SyntaxKind.SourceFile || node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.ModuleDeclaration; + if (!isInAppropriateContext) { + grammarErrorOnFirstToken(node, errorMessage); + } + return !isInAppropriateContext; + } + + function checkExportSpecifier(node: ExportSpecifier) { + checkAliasSymbol(node); + const hasModuleSpecifier = node.parent.parent.moduleSpecifier !== undefined; + checkModuleExportName(node.propertyName, hasModuleSpecifier); + checkModuleExportName(node.name); + if (getEmitDeclarations(compilerOptions)) { + collectLinkedAliases(node.propertyName || node.name, /*setVisibility*/ true); + } + if (!hasModuleSpecifier) { + const exportedName = node.propertyName || node.name; + if (exportedName.kind === SyntaxKind.StringLiteral) { + return; // Skip for invalid syntax like this: export { "x" } + } + // find immediate value referenced by exported name (SymbolFlags.Alias is set so we don't chase down aliases) + const symbol = resolveName(exportedName, exportedName.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (symbol && (symbol === undefinedSymbol || symbol === globalThisSymbol || symbol.declarations && isGlobalSourceFile(getDeclarationContainer(symbol.declarations[0])))) { + error(exportedName, Diagnostics.Cannot_export_0_Only_local_declarations_can_be_exported_from_a_module, idText(exportedName)); + } + else { + markLinkedReferences(node, ReferenceHint.ExportSpecifier); + } + } + else { + if ( + getESModuleInterop(compilerOptions) && + moduleKind !== ModuleKind.System && + (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) && + moduleExportNameIsDefault(node.propertyName || node.name) + ) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ImportDefault); + } + } + } + + function checkExportAssignment(node: ExportAssignment) { + const illegalContextMessage = node.isExportEquals + ? Diagnostics.An_export_assignment_must_be_at_the_top_level_of_a_file_or_module_declaration + : Diagnostics.A_default_export_must_be_at_the_top_level_of_a_file_or_module_declaration; + if (checkGrammarModuleElementContext(node, illegalContextMessage)) { + // If we hit an export assignment in an illegal context, just bail out to avoid cascading errors. + return; + } + + const container = node.parent.kind === SyntaxKind.SourceFile ? node.parent : node.parent.parent as ModuleDeclaration; + if (container.kind === SyntaxKind.ModuleDeclaration && !isAmbientModule(container)) { + if (node.isExportEquals) { + error(node, Diagnostics.An_export_assignment_cannot_be_used_in_a_namespace); + } + else { + error(node, Diagnostics.A_default_export_can_only_be_used_in_an_ECMAScript_style_module); + } + + return; + } + // Grammar checking + if (!checkGrammarModifiers(node) && hasEffectiveModifiers(node)) { + grammarErrorOnFirstToken(node, Diagnostics.An_export_assignment_cannot_have_modifiers); + } + + const typeAnnotationNode = getEffectiveTypeAnnotationNode(node); + if (typeAnnotationNode) { + checkTypeAssignableTo(checkExpressionCached(node.expression), getTypeFromTypeNode(typeAnnotationNode), node.expression); + } + + const isIllegalExportDefaultInCJS = !node.isExportEquals && + !(node.flags & NodeFlags.Ambient) && + compilerOptions.verbatimModuleSyntax && + (moduleKind === ModuleKind.CommonJS || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS); + + if (node.expression.kind === SyntaxKind.Identifier) { + const id = node.expression as Identifier; + const sym = getExportSymbolOfValueSymbolIfExported(resolveEntityName(id, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, node)); + if (sym) { + markLinkedReferences(node, ReferenceHint.ExportAssignment); + const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(sym, SymbolFlags.Value); + // If not a value, we're interpreting the identifier as a type export, along the lines of (`export { Id as default }`) + if (getSymbolFlags(sym) & SymbolFlags.Value) { + // However if it is a value, we need to check it's being used correctly + checkExpressionCached(id); + if (!isIllegalExportDefaultInCJS && !(node.flags & NodeFlags.Ambient) && compilerOptions.verbatimModuleSyntax && typeOnlyDeclaration) { + error( + id, + node.isExportEquals + ? Diagnostics.An_export_declaration_must_reference_a_real_value_when_verbatimModuleSyntax_is_enabled_but_0_resolves_to_a_type_only_declaration + : Diagnostics.An_export_default_must_reference_a_real_value_when_verbatimModuleSyntax_is_enabled_but_0_resolves_to_a_type_only_declaration, + idText(id), + ); + } + } + else if (!isIllegalExportDefaultInCJS && !(node.flags & NodeFlags.Ambient) && compilerOptions.verbatimModuleSyntax) { + error( + id, + node.isExportEquals + ? Diagnostics.An_export_declaration_must_reference_a_value_when_verbatimModuleSyntax_is_enabled_but_0_only_refers_to_a_type + : Diagnostics.An_export_default_must_reference_a_value_when_verbatimModuleSyntax_is_enabled_but_0_only_refers_to_a_type, + idText(id), + ); + } + + if (!isIllegalExportDefaultInCJS && !(node.flags & NodeFlags.Ambient) && getIsolatedModules(compilerOptions) && !(sym.flags & SymbolFlags.Value)) { + const nonLocalMeanings = getSymbolFlags(sym, /*excludeTypeOnlyMeanings*/ false, /*excludeLocalMeanings*/ true); + if ( + sym.flags & SymbolFlags.Alias + && nonLocalMeanings & SymbolFlags.Type + && !(nonLocalMeanings & SymbolFlags.Value) + && (!typeOnlyDeclaration || getSourceFileOfNode(typeOnlyDeclaration) !== getSourceFileOfNode(node)) + ) { + // import { SomeType } from "./someModule"; + // export default SomeType; OR + // export = SomeType; + error( + id, + node.isExportEquals ? + Diagnostics._0_resolves_to_a_type_and_must_be_marked_type_only_in_this_file_before_re_exporting_when_1_is_enabled_Consider_using_import_type_where_0_is_imported + : Diagnostics._0_resolves_to_a_type_and_must_be_marked_type_only_in_this_file_before_re_exporting_when_1_is_enabled_Consider_using_export_type_0_as_default, + idText(id), + isolatedModulesLikeFlagName, + ); + } + else if (typeOnlyDeclaration && getSourceFileOfNode(typeOnlyDeclaration) !== getSourceFileOfNode(node)) { + // import { SomeTypeOnlyValue } from "./someModule"; + // export default SomeTypeOnlyValue; OR + // export = SomeTypeOnlyValue; + addTypeOnlyDeclarationRelatedInfo( + error( + id, + node.isExportEquals ? + Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_marked_type_only_in_this_file_before_re_exporting_when_1_is_enabled_Consider_using_import_type_where_0_is_imported + : Diagnostics._0_resolves_to_a_type_only_declaration_and_must_be_marked_type_only_in_this_file_before_re_exporting_when_1_is_enabled_Consider_using_export_type_0_as_default, + idText(id), + isolatedModulesLikeFlagName, + ), + typeOnlyDeclaration, + idText(id), + ); + } + } + } + else { + checkExpressionCached(id); // doesn't resolve, check as expression to mark as error + } + + if (getEmitDeclarations(compilerOptions)) { + collectLinkedAliases(id, /*setVisibility*/ true); + } + } + else { + checkExpressionCached(node.expression); + } + + if (isIllegalExportDefaultInCJS) { + error(node, Diagnostics.ESM_syntax_is_not_allowed_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + + checkExternalModuleExports(container); + + if ((node.flags & NodeFlags.Ambient) && !isEntityNameExpression(node.expression)) { + grammarErrorOnNode(node.expression, Diagnostics.The_expression_of_an_export_assignment_must_be_an_identifier_or_qualified_name_in_an_ambient_context); + } + + if (node.isExportEquals) { + // Forbid export= in esm implementation files, and esm mode declaration files + if ( + moduleKind >= ModuleKind.ES2015 && + moduleKind !== ModuleKind.Preserve && + ((node.flags & NodeFlags.Ambient && getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.ESNext) || + (!(node.flags & NodeFlags.Ambient) && getSourceFileOfNode(node).impliedNodeFormat !== ModuleKind.CommonJS)) + ) { + // export assignment is not supported in es6 modules + grammarErrorOnNode(node, Diagnostics.Export_assignment_cannot_be_used_when_targeting_ECMAScript_modules_Consider_using_export_default_or_another_module_format_instead); + } + else if (moduleKind === ModuleKind.System && !(node.flags & NodeFlags.Ambient)) { + // system modules does not support export assignment + grammarErrorOnNode(node, Diagnostics.Export_assignment_is_not_supported_when_module_flag_is_system); + } + } + } + + function hasExportedMembers(moduleSymbol: Symbol) { + return forEachEntry(moduleSymbol.exports!, (_, id) => id !== "export="); + } + + function checkExternalModuleExports(node: SourceFile | ModuleDeclaration) { + const moduleSymbol = getSymbolOfDeclaration(node); + const links = getSymbolLinks(moduleSymbol); + if (!links.exportsChecked) { + const exportEqualsSymbol = moduleSymbol.exports!.get("export=" as __String); + if (exportEqualsSymbol && hasExportedMembers(moduleSymbol)) { + const declaration = getDeclarationOfAliasSymbol(exportEqualsSymbol) || exportEqualsSymbol.valueDeclaration; + if (declaration && !isTopLevelInExternalModuleAugmentation(declaration) && !isInJSFile(declaration)) { + error(declaration, Diagnostics.An_export_assignment_cannot_be_used_in_a_module_with_other_exported_elements); + } + } + // Checks for export * conflicts + const exports = getExportsOfModule(moduleSymbol); + if (exports) { + exports.forEach(({ declarations, flags }, id) => { + if (id === "__export") { + return; + } + // ECMA262: 15.2.1.1 It is a Syntax Error if the ExportedNames of ModuleItemList contains any duplicate entries. + // (TS Exceptions: namespaces, function overloads, enums, and interfaces) + if (flags & (SymbolFlags.Namespace | SymbolFlags.Enum)) { + return; + } + const exportedDeclarationsCount = countWhere(declarations, and(isNotOverloadAndNotAccessor, not(isInterfaceDeclaration))); + if (flags & SymbolFlags.TypeAlias && exportedDeclarationsCount <= 2) { + // it is legal to merge type alias with other values + // so count should be either 1 (just type alias) or 2 (type alias + merged value) + return; + } + if (exportedDeclarationsCount > 1) { + if (!isDuplicatedCommonJSExport(declarations)) { + for (const declaration of declarations!) { + if (isNotOverload(declaration)) { + diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Cannot_redeclare_exported_variable_0, unescapeLeadingUnderscores(id))); + } + } + } + } + }); + } + links.exportsChecked = true; + } + } + + function isDuplicatedCommonJSExport(declarations: Declaration[] | undefined) { + return declarations + && declarations.length > 1 + && declarations.every(d => isInJSFile(d) && isAccessExpression(d) && (isExportsIdentifier(d.expression) || isModuleExportsAccessExpression(d.expression))); + } + + function checkSourceElement(node: Node | undefined): void { + if (node) { + const saveCurrentNode = currentNode; + currentNode = node; + instantiationCount = 0; + checkSourceElementWorker(node); + currentNode = saveCurrentNode; + } + } + + function checkSourceElementWorker(node: Node): void { + if (getNodeCheckFlags(node) & NodeCheckFlags.PartiallyTypeChecked) { + return; + } + + if (canHaveJSDoc(node)) { + forEach(node.jsDoc, ({ comment, tags }) => { + checkJSDocCommentWorker(comment); + forEach(tags, tag => { + checkJSDocCommentWorker(tag.comment); + if (isInJSFile(node)) { + checkSourceElement(tag); + } + }); + }); + } + + const kind = node.kind; + if (cancellationToken) { + // Only bother checking on a few construct kinds. We don't want to be excessively + // hitting the cancellation token on every node we check. + switch (kind) { + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.FunctionDeclaration: + cancellationToken.throwIfCancellationRequested(); + } + } + if (kind >= SyntaxKind.FirstStatement && kind <= SyntaxKind.LastStatement && canHaveFlowNode(node) && node.flowNode && !isReachableFlowNode(node.flowNode)) { + errorOrSuggestion(compilerOptions.allowUnreachableCode === false, node, Diagnostics.Unreachable_code_detected); + } + + // If editing this, keep `isSourceElement` in utilities up to date. + switch (kind) { + case SyntaxKind.TypeParameter: + return checkTypeParameter(node as TypeParameterDeclaration); + case SyntaxKind.Parameter: + return checkParameter(node as ParameterDeclaration); + case SyntaxKind.PropertyDeclaration: + return checkPropertyDeclaration(node as PropertyDeclaration); + case SyntaxKind.PropertySignature: + return checkPropertySignature(node as PropertySignature); + case SyntaxKind.ConstructorType: + case SyntaxKind.FunctionType: + case SyntaxKind.CallSignature: + case SyntaxKind.ConstructSignature: + case SyntaxKind.IndexSignature: + return checkSignatureDeclaration(node as SignatureDeclaration); + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + return checkMethodDeclaration(node as MethodDeclaration | MethodSignature); + case SyntaxKind.ClassStaticBlockDeclaration: + return checkClassStaticBlockDeclaration(node as ClassStaticBlockDeclaration); + case SyntaxKind.Constructor: + return checkConstructorDeclaration(node as ConstructorDeclaration); + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return checkAccessorDeclaration(node as AccessorDeclaration); + case SyntaxKind.TypeReference: + return checkTypeReferenceNode(node as TypeReferenceNode); + case SyntaxKind.TypePredicate: + return checkTypePredicate(node as TypePredicateNode); + case SyntaxKind.TypeQuery: + return checkTypeQuery(node as TypeQueryNode); + case SyntaxKind.TypeLiteral: + return checkTypeLiteral(node as TypeLiteralNode); + case SyntaxKind.ArrayType: + return checkArrayType(node as ArrayTypeNode); + case SyntaxKind.TupleType: + return checkTupleType(node as TupleTypeNode); + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + return checkUnionOrIntersectionType(node as UnionOrIntersectionTypeNode); + case SyntaxKind.ParenthesizedType: + case SyntaxKind.OptionalType: + case SyntaxKind.RestType: + return checkSourceElement((node as ParenthesizedTypeNode | OptionalTypeNode | RestTypeNode).type); + case SyntaxKind.ThisType: + return checkThisType(node as ThisTypeNode); + case SyntaxKind.TypeOperator: + return checkTypeOperator(node as TypeOperatorNode); + case SyntaxKind.ConditionalType: + return checkConditionalType(node as ConditionalTypeNode); + case SyntaxKind.InferType: + return checkInferType(node as InferTypeNode); + case SyntaxKind.TemplateLiteralType: + return checkTemplateLiteralType(node as TemplateLiteralTypeNode); + case SyntaxKind.ImportType: + return checkImportType(node as ImportTypeNode); + case SyntaxKind.NamedTupleMember: + return checkNamedTupleMember(node as NamedTupleMember); + case SyntaxKind.JSDocAugmentsTag: + return checkJSDocAugmentsTag(node as JSDocAugmentsTag); + case SyntaxKind.JSDocImplementsTag: + return checkJSDocImplementsTag(node as JSDocImplementsTag); + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.JSDocEnumTag: + return checkJSDocTypeAliasTag(node as JSDocTypedefTag); + case SyntaxKind.JSDocTemplateTag: + return checkJSDocTemplateTag(node as JSDocTemplateTag); + case SyntaxKind.JSDocTypeTag: + return checkJSDocTypeTag(node as JSDocTypeTag); + case SyntaxKind.JSDocLink: + case SyntaxKind.JSDocLinkCode: + case SyntaxKind.JSDocLinkPlain: + return checkJSDocLinkLikeTag(node as JSDocLink | JSDocLinkCode | JSDocLinkPlain); + case SyntaxKind.JSDocParameterTag: + return checkJSDocParameterTag(node as JSDocParameterTag); + case SyntaxKind.JSDocPropertyTag: + return checkJSDocPropertyTag(node as JSDocPropertyTag); + case SyntaxKind.JSDocFunctionType: + checkJSDocFunctionType(node as JSDocFunctionType); + // falls through + case SyntaxKind.JSDocNonNullableType: + case SyntaxKind.JSDocNullableType: + case SyntaxKind.JSDocAllType: + case SyntaxKind.JSDocUnknownType: + case SyntaxKind.JSDocTypeLiteral: + checkJSDocTypeIsInJsFile(node); + forEachChild(node, checkSourceElement); + return; + case SyntaxKind.JSDocVariadicType: + checkJSDocVariadicType(node as JSDocVariadicType); + return; + case SyntaxKind.JSDocTypeExpression: + return checkSourceElement((node as JSDocTypeExpression).type); + case SyntaxKind.JSDocPublicTag: + case SyntaxKind.JSDocProtectedTag: + case SyntaxKind.JSDocPrivateTag: + return checkJSDocAccessibilityModifiers(node as JSDocPublicTag | JSDocProtectedTag | JSDocPrivateTag); + case SyntaxKind.JSDocSatisfiesTag: + return checkJSDocSatisfiesTag(node as JSDocSatisfiesTag); + case SyntaxKind.JSDocThisTag: + return checkJSDocThisTag(node as JSDocThisTag); + case SyntaxKind.JSDocImportTag: + return checkJSDocImportTag(node as JSDocImportTag); + case SyntaxKind.IndexedAccessType: + return checkIndexedAccessType(node as IndexedAccessTypeNode); + case SyntaxKind.MappedType: + return checkMappedType(node as MappedTypeNode); + case SyntaxKind.FunctionDeclaration: + return checkFunctionDeclaration(node as FunctionDeclaration); + case SyntaxKind.Block: + case SyntaxKind.ModuleBlock: + return checkBlock(node as Block); + case SyntaxKind.VariableStatement: + return checkVariableStatement(node as VariableStatement); + case SyntaxKind.ExpressionStatement: + return checkExpressionStatement(node as ExpressionStatement); + case SyntaxKind.IfStatement: + return checkIfStatement(node as IfStatement); + case SyntaxKind.DoStatement: + return checkDoStatement(node as DoStatement); + case SyntaxKind.WhileStatement: + return checkWhileStatement(node as WhileStatement); + case SyntaxKind.ForStatement: + return checkForStatement(node as ForStatement); + case SyntaxKind.ForInStatement: + return checkForInStatement(node as ForInStatement); + case SyntaxKind.ForOfStatement: + return checkForOfStatement(node as ForOfStatement); + case SyntaxKind.ContinueStatement: + case SyntaxKind.BreakStatement: + return checkBreakOrContinueStatement(node as BreakOrContinueStatement); + case SyntaxKind.ReturnStatement: + return checkReturnStatement(node as ReturnStatement); + case SyntaxKind.WithStatement: + return checkWithStatement(node as WithStatement); + case SyntaxKind.SwitchStatement: + return checkSwitchStatement(node as SwitchStatement); + case SyntaxKind.LabeledStatement: + return checkLabeledStatement(node as LabeledStatement); + case SyntaxKind.ThrowStatement: + return checkThrowStatement(node as ThrowStatement); + case SyntaxKind.TryStatement: + return checkTryStatement(node as TryStatement); + case SyntaxKind.VariableDeclaration: + return checkVariableDeclaration(node as VariableDeclaration); + case SyntaxKind.BindingElement: + return checkBindingElement(node as BindingElement); + case SyntaxKind.ClassDeclaration: + return checkClassDeclaration(node as ClassDeclaration); + case SyntaxKind.InterfaceDeclaration: + return checkInterfaceDeclaration(node as InterfaceDeclaration); + case SyntaxKind.TypeAliasDeclaration: + return checkTypeAliasDeclaration(node as TypeAliasDeclaration); + case SyntaxKind.EnumDeclaration: + return checkEnumDeclaration(node as EnumDeclaration); + case SyntaxKind.ModuleDeclaration: + return checkModuleDeclaration(node as ModuleDeclaration); + case SyntaxKind.ImportDeclaration: + return checkImportDeclaration(node as ImportDeclaration); + case SyntaxKind.ImportEqualsDeclaration: + return checkImportEqualsDeclaration(node as ImportEqualsDeclaration); + case SyntaxKind.ExportDeclaration: + return checkExportDeclaration(node as ExportDeclaration); + case SyntaxKind.ExportAssignment: + return checkExportAssignment(node as ExportAssignment); + case SyntaxKind.EmptyStatement: + case SyntaxKind.DebuggerStatement: + checkGrammarStatementInAmbientContext(node); + return; + case SyntaxKind.MissingDeclaration: + return checkMissingDeclaration(node); + } + } + + function checkJSDocCommentWorker(node: string | readonly JSDocComment[] | undefined) { + if (isArray(node)) { + forEach(node, tag => { + if (isJSDocLinkLike(tag)) { + checkSourceElement(tag); + } + }); + } + } + + function checkJSDocTypeIsInJsFile(node: Node): void { + if (!isInJSFile(node)) { + if (isJSDocNonNullableType(node) || isJSDocNullableType(node)) { + const token = tokenToString(isJSDocNonNullableType(node) ? SyntaxKind.ExclamationToken : SyntaxKind.QuestionToken); + const diagnostic = node.postfix + ? Diagnostics._0_at_the_end_of_a_type_is_not_valid_TypeScript_syntax_Did_you_mean_to_write_1 + : Diagnostics._0_at_the_start_of_a_type_is_not_valid_TypeScript_syntax_Did_you_mean_to_write_1; + const typeNode = node.type; + const type = getTypeFromTypeNode(typeNode); + grammarErrorOnNode( + node, + diagnostic, + token, + typeToString( + isJSDocNullableType(node) && !(type === neverType || type === voidType) + ? getUnionType(append([type, undefinedType], node.postfix ? undefined : nullType)) : type, + ), + ); + } + else { + grammarErrorOnNode(node, Diagnostics.JSDoc_types_can_only_be_used_inside_documentation_comments); + } + } + } + + function checkJSDocVariadicType(node: JSDocVariadicType): void { + checkJSDocTypeIsInJsFile(node); + checkSourceElement(node.type); + + // Only legal location is in the *last* parameter tag or last parameter of a JSDoc function. + const { parent } = node; + if (isParameter(parent) && isJSDocFunctionType(parent.parent)) { + if (last(parent.parent.parameters) !== parent) { + error(node, Diagnostics.A_rest_parameter_must_be_last_in_a_parameter_list); + } + return; + } + + if (!isJSDocTypeExpression(parent)) { + error(node, Diagnostics.JSDoc_may_only_appear_in_the_last_parameter_of_a_signature); + } + + const paramTag = node.parent.parent; + if (!isJSDocParameterTag(paramTag)) { + error(node, Diagnostics.JSDoc_may_only_appear_in_the_last_parameter_of_a_signature); + return; + } + + const param = getParameterSymbolFromJSDoc(paramTag); + if (!param) { + // We will error in `checkJSDocParameterTag`. + return; + } + + const host = getHostSignatureFromJSDoc(paramTag); + if (!host || last(host.parameters).symbol !== param) { + error(node, Diagnostics.A_rest_parameter_must_be_last_in_a_parameter_list); + } + } + + function getTypeFromJSDocVariadicType(node: JSDocVariadicType): Type { + const type = getTypeFromTypeNode(node.type); + const { parent } = node; + const paramTag = node.parent.parent; + if (isJSDocTypeExpression(node.parent) && isJSDocParameterTag(paramTag)) { + // Else we will add a diagnostic, see `checkJSDocVariadicType`. + const host = getHostSignatureFromJSDoc(paramTag); + const isCallbackTag = isJSDocCallbackTag(paramTag.parent.parent); + if (host || isCallbackTag) { + /* + Only return an array type if the corresponding parameter is marked as a rest parameter, or if there are no parameters. + So in the following situation we will not create an array type: + /** @param {...number} a * / + function f(a) {} + Because `a` will just be of type `number | undefined`. A synthetic `...args` will also be added, which *will* get an array type. + */ + const lastParamDeclaration = isCallbackTag + ? lastOrUndefined((paramTag.parent.parent as unknown as JSDocCallbackTag).typeExpression.parameters) + : lastOrUndefined(host!.parameters); + const symbol = getParameterSymbolFromJSDoc(paramTag); + if ( + !lastParamDeclaration || + symbol && lastParamDeclaration.symbol === symbol && isRestParameter(lastParamDeclaration) + ) { + return createArrayType(type); + } + } + } + if (isParameter(parent) && isJSDocFunctionType(parent.parent)) { + return createArrayType(type); + } + return addOptionality(type); + } + + // Function and class expression bodies are checked after all statements in the enclosing body. This is + // to ensure constructs like the following are permitted: + // const foo = function () { + // const s = foo(); + // return "hello"; + // } + // Here, performing a full type check of the body of the function expression whilst in the process of + // determining the type of foo would cause foo to be given type any because of the recursive reference. + // Delaying the type check of the body ensures foo has been assigned a type. + function checkNodeDeferred(node: Node) { + const enclosingFile = getSourceFileOfNode(node); + const links = getNodeLinks(enclosingFile); + if (!(links.flags & NodeCheckFlags.TypeChecked)) { + links.deferredNodes ||= new Set(); + links.deferredNodes.add(node); + } + else { + Debug.assert(!links.deferredNodes, "A type-checked file should have no deferred nodes."); + } + } + + function checkDeferredNodes(context: SourceFile) { + const links = getNodeLinks(context); + if (links.deferredNodes) { + links.deferredNodes.forEach(checkDeferredNode); + } + links.deferredNodes = undefined; + } + + function checkDeferredNode(node: Node) { + tracing?.push(tracing.Phase.Check, "checkDeferredNode", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); + const saveCurrentNode = currentNode; + currentNode = node; + instantiationCount = 0; + switch (node.kind) { + case SyntaxKind.CallExpression: + case SyntaxKind.NewExpression: + case SyntaxKind.TaggedTemplateExpression: + case SyntaxKind.Decorator: + case SyntaxKind.JsxOpeningElement: + // These node kinds are deferred checked when overload resolution fails + // To save on work, we ensure the arguments are checked just once, in + // a deferred way + resolveUntypedCall(node as CallLikeExpression); + break; + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + checkFunctionExpressionOrObjectLiteralMethodDeferred(node as FunctionExpression); + break; + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + checkAccessorDeclaration(node as AccessorDeclaration); + break; + case SyntaxKind.ClassExpression: + checkClassExpressionDeferred(node as ClassExpression); + break; + case SyntaxKind.TypeParameter: + checkTypeParameterDeferred(node as TypeParameterDeclaration); + break; + case SyntaxKind.JsxSelfClosingElement: + checkJsxSelfClosingElementDeferred(node as JsxSelfClosingElement); + break; + case SyntaxKind.JsxElement: + checkJsxElementDeferred(node as JsxElement); + break; + case SyntaxKind.TypeAssertionExpression: + case SyntaxKind.AsExpression: + case SyntaxKind.ParenthesizedExpression: + checkAssertionDeferred(node as AssertionExpression | JSDocTypeAssertion); + break; + case SyntaxKind.VoidExpression: + checkExpression((node as VoidExpression).expression); + break; + case SyntaxKind.BinaryExpression: + if (isInstanceOfExpression(node)) { + resolveUntypedCall(node); + } + break; + } + currentNode = saveCurrentNode; + tracing?.pop(); + } + + function checkSourceFile(node: SourceFile, nodesToCheck: Node[] | undefined) { + tracing?.push(tracing.Phase.Check, nodesToCheck ? "checkSourceFileNodes" : "checkSourceFile", { path: node.path }, /*separateBeginAndEnd*/ true); + const beforeMark = nodesToCheck ? "beforeCheckNodes" : "beforeCheck"; + const afterMark = nodesToCheck ? "afterCheckNodes" : "afterCheck"; + performance.mark(beforeMark); + nodesToCheck ? checkSourceFileNodesWorker(node, nodesToCheck) : checkSourceFileWorker(node); + performance.mark(afterMark); + performance.measure("Check", beforeMark, afterMark); + tracing?.pop(); + } + + function unusedIsError(kind: UnusedKind, isAmbient: boolean): boolean { + if (isAmbient) { + return false; + } + switch (kind) { + case UnusedKind.Local: + return !!compilerOptions.noUnusedLocals; + case UnusedKind.Parameter: + return !!compilerOptions.noUnusedParameters; + default: + return Debug.assertNever(kind); + } + } + + function getPotentiallyUnusedIdentifiers(sourceFile: SourceFile): readonly PotentiallyUnusedIdentifier[] { + return allPotentiallyUnusedIdentifiers.get(sourceFile.path) || emptyArray; + } + + // Fully type check a source file and collect the relevant diagnostics. + function checkSourceFileWorker(node: SourceFile) { + const links = getNodeLinks(node); + if (!(links.flags & NodeCheckFlags.TypeChecked)) { + if (skipTypeChecking(node, compilerOptions, host)) { + return; + } + + // Grammar checking + checkGrammarSourceFile(node); + + clear(potentialThisCollisions); + clear(potentialNewTargetCollisions); + clear(potentialWeakMapSetCollisions); + clear(potentialReflectCollisions); + clear(potentialUnusedRenamedBindingElementsInTypes); + + if (links.flags & NodeCheckFlags.PartiallyTypeChecked) { + potentialThisCollisions = links.potentialThisCollisions!; + potentialNewTargetCollisions = links.potentialNewTargetCollisions!; + potentialWeakMapSetCollisions = links.potentialWeakMapSetCollisions!; + potentialReflectCollisions = links.potentialReflectCollisions!; + potentialUnusedRenamedBindingElementsInTypes = links.potentialUnusedRenamedBindingElementsInTypes!; + } + + forEach(node.statements, checkSourceElement); + checkSourceElement(node.endOfFileToken); + + checkDeferredNodes(node); + + if (isExternalOrCommonJsModule(node)) { + registerForUnusedIdentifiersCheck(node); + } + + addLazyDiagnostic(() => { + // This relies on the results of other lazy diagnostics, so must be computed after them + if (!node.isDeclarationFile && (compilerOptions.noUnusedLocals || compilerOptions.noUnusedParameters)) { + checkUnusedIdentifiers(getPotentiallyUnusedIdentifiers(node), (containingNode, kind, diag) => { + if (!containsParseError(containingNode) && unusedIsError(kind, !!(containingNode.flags & NodeFlags.Ambient))) { + diagnostics.add(diag); + } + }); + } + if (!node.isDeclarationFile) { + checkPotentialUncheckedRenamedBindingElementsInTypes(); + } + }); + + if (isExternalOrCommonJsModule(node)) { + checkExternalModuleExports(node); + } + + if (potentialThisCollisions.length) { + forEach(potentialThisCollisions, checkIfThisIsCapturedInEnclosingScope); + clear(potentialThisCollisions); + } + + if (potentialNewTargetCollisions.length) { + forEach(potentialNewTargetCollisions, checkIfNewTargetIsCapturedInEnclosingScope); + clear(potentialNewTargetCollisions); + } + + if (potentialWeakMapSetCollisions.length) { + forEach(potentialWeakMapSetCollisions, checkWeakMapSetCollision); + clear(potentialWeakMapSetCollisions); + } + + if (potentialReflectCollisions.length) { + forEach(potentialReflectCollisions, checkReflectCollision); + clear(potentialReflectCollisions); + } + + links.flags |= NodeCheckFlags.TypeChecked; + } + } + + function checkSourceFileNodesWorker(file: SourceFile, nodes: readonly Node[]) { + const links = getNodeLinks(file); + if (!(links.flags & NodeCheckFlags.TypeChecked)) { + if (skipTypeChecking(file, compilerOptions, host)) { + return; + } + + // Grammar checking + checkGrammarSourceFile(file); + + clear(potentialThisCollisions); + clear(potentialNewTargetCollisions); + clear(potentialWeakMapSetCollisions); + clear(potentialReflectCollisions); + clear(potentialUnusedRenamedBindingElementsInTypes); + + forEach(nodes, checkSourceElement); + + checkDeferredNodes(file); + + (links.potentialThisCollisions || (links.potentialThisCollisions = [])).push(...potentialThisCollisions); + (links.potentialNewTargetCollisions || (links.potentialNewTargetCollisions = [])).push(...potentialNewTargetCollisions); + (links.potentialWeakMapSetCollisions || (links.potentialWeakMapSetCollisions = [])).push(...potentialWeakMapSetCollisions); + (links.potentialReflectCollisions || (links.potentialReflectCollisions = [])).push(...potentialReflectCollisions); + (links.potentialUnusedRenamedBindingElementsInTypes || (links.potentialUnusedRenamedBindingElementsInTypes = [])).push( + ...potentialUnusedRenamedBindingElementsInTypes, + ); + + links.flags |= NodeCheckFlags.PartiallyTypeChecked; + for (const node of nodes) { + const nodeLinks = getNodeLinks(node); + nodeLinks.flags |= NodeCheckFlags.PartiallyTypeChecked; + } + } + } + + function getDiagnostics(sourceFile: SourceFile, ct: CancellationToken, nodesToCheck?: Node[]): Diagnostic[] { + try { + // Record the cancellation token so it can be checked later on during checkSourceElement. + // Do this in a finally block so we can ensure that it gets reset back to nothing after + // this call is done. + cancellationToken = ct; + return getDiagnosticsWorker(sourceFile, nodesToCheck); + } + finally { + cancellationToken = undefined; + } + } + + function ensurePendingDiagnosticWorkComplete() { + // Invoke any existing lazy diagnostics to add them, clear the backlog of diagnostics + for (const cb of deferredDiagnosticsCallbacks) { + cb(); + } + deferredDiagnosticsCallbacks = []; + } + + function checkSourceFileWithEagerDiagnostics(sourceFile: SourceFile, nodesToCheck?: Node[]) { + ensurePendingDiagnosticWorkComplete(); + // then setup diagnostics for immediate invocation (as we are about to collect them, and + // this avoids the overhead of longer-lived callbacks we don't need to allocate) + // This also serves to make the shift to possibly lazy diagnostics transparent to serial command-line scenarios + // (as in those cases, all the diagnostics will still be computed as the appropriate place in the tree, + // thus much more likely retaining the same union ordering as before we had lazy diagnostics) + const oldAddLazyDiagnostics = addLazyDiagnostic; + addLazyDiagnostic = cb => cb(); + checkSourceFile(sourceFile, nodesToCheck); + addLazyDiagnostic = oldAddLazyDiagnostics; + } + + function getDiagnosticsWorker(sourceFile: SourceFile, nodesToCheck: Node[] | undefined): Diagnostic[] { + if (sourceFile) { + ensurePendingDiagnosticWorkComplete(); + // Some global diagnostics are deferred until they are needed and + // may not be reported in the first call to getGlobalDiagnostics. + // We should catch these changes and report them. + const previousGlobalDiagnostics = diagnostics.getGlobalDiagnostics(); + const previousGlobalDiagnosticsSize = previousGlobalDiagnostics.length; + + checkSourceFileWithEagerDiagnostics(sourceFile, nodesToCheck); + const semanticDiagnostics = diagnostics.getDiagnostics(sourceFile.fileName); + if (nodesToCheck) { + // No need to get global diagnostics. + return semanticDiagnostics; + } + const currentGlobalDiagnostics = diagnostics.getGlobalDiagnostics(); + if (currentGlobalDiagnostics !== previousGlobalDiagnostics) { + // If the arrays are not the same reference, new diagnostics were added. + const deferredGlobalDiagnostics = relativeComplement(previousGlobalDiagnostics, currentGlobalDiagnostics, compareDiagnostics); + return concatenate(deferredGlobalDiagnostics, semanticDiagnostics); + } + else if (previousGlobalDiagnosticsSize === 0 && currentGlobalDiagnostics.length > 0) { + // If the arrays are the same reference, but the length has changed, a single + // new diagnostic was added as DiagnosticCollection attempts to reuse the + // same array. + return concatenate(currentGlobalDiagnostics, semanticDiagnostics); + } + + return semanticDiagnostics; + } + + // Global diagnostics are always added when a file is not provided to + // getDiagnostics + forEach(host.getSourceFiles(), file => checkSourceFileWithEagerDiagnostics(file)); + return diagnostics.getDiagnostics(); + } + + function getGlobalDiagnostics(): Diagnostic[] { + ensurePendingDiagnosticWorkComplete(); + return diagnostics.getGlobalDiagnostics(); + } + + // Language service support + + function getSymbolsInScope(location: Node, meaning: SymbolFlags): Symbol[] { + if (location.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return []; + } + + const symbols = createSymbolTable(); + let isStaticSymbol = false; + + populateSymbols(); + + symbols.delete(InternalSymbolName.This); // Not a symbol, a keyword + return symbolsToArray(symbols); + + function populateSymbols() { + while (location) { + if (canHaveLocals(location) && location.locals && !isGlobalSourceFile(location)) { + copySymbols(location.locals, meaning); + } + + switch (location.kind) { + case SyntaxKind.SourceFile: + if (!isExternalModule(location as SourceFile)) break; + // falls through + case SyntaxKind.ModuleDeclaration: + copyLocallyVisibleExportSymbols(getSymbolOfDeclaration(location as ModuleDeclaration | SourceFile).exports!, meaning & SymbolFlags.ModuleMember); + break; + case SyntaxKind.EnumDeclaration: + copySymbols(getSymbolOfDeclaration(location as EnumDeclaration).exports!, meaning & SymbolFlags.EnumMember); + break; + case SyntaxKind.ClassExpression: + const className = (location as ClassExpression).name; + if (className) { + copySymbol((location as ClassExpression).symbol, meaning); + } + + // this fall-through is necessary because we would like to handle + // type parameter inside class expression similar to how we handle it in classDeclaration and interface Declaration. + // falls through + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + // If we didn't come from static member of class or interface, + // add the type parameters into the symbol table + // (type parameters of classDeclaration/classExpression and interface are in member property of the symbol. + // Note: that the memberFlags come from previous iteration. + if (!isStaticSymbol) { + copySymbols(getMembersOfSymbol(getSymbolOfDeclaration(location as ClassDeclaration | InterfaceDeclaration)), meaning & SymbolFlags.Type); + } + break; + case SyntaxKind.FunctionExpression: + const funcName = (location as FunctionExpression).name; + if (funcName) { + copySymbol((location as FunctionExpression).symbol, meaning); + } + break; + } + + if (introducesArgumentsExoticObject(location)) { + copySymbol(argumentsSymbol, meaning); + } + + isStaticSymbol = isStatic(location); + location = location.parent; + } + + copySymbols(globals, meaning); + } + + /** + * Copy the given symbol into symbol tables if the symbol has the given meaning + * and it doesn't already existed in the symbol table + * @param key a key for storing in symbol table; if undefined, use symbol.name + * @param symbol the symbol to be added into symbol table + * @param meaning meaning of symbol to filter by before adding to symbol table + */ + function copySymbol(symbol: Symbol, meaning: SymbolFlags): void { + if (getCombinedLocalAndExportSymbolFlags(symbol) & meaning) { + const id = symbol.escapedName; + // We will copy all symbol regardless of its reserved name because + // symbolsToArray will check whether the key is a reserved name and + // it will not copy symbol with reserved name to the array + if (!symbols.has(id)) { + symbols.set(id, symbol); + } + } + } + + function copySymbols(source: SymbolTable, meaning: SymbolFlags): void { + if (meaning) { + source.forEach(symbol => { + copySymbol(symbol, meaning); + }); + } + } + + function copyLocallyVisibleExportSymbols(source: SymbolTable, meaning: SymbolFlags): void { + if (meaning) { + source.forEach(symbol => { + // Similar condition as in `resolveNameHelper` + if (!getDeclarationOfKind(symbol, SyntaxKind.ExportSpecifier) && !getDeclarationOfKind(symbol, SyntaxKind.NamespaceExport) && symbol.escapedName !== InternalSymbolName.Default) { + copySymbol(symbol, meaning); + } + }); + } + } + } + + function isTypeDeclarationName(name: Node): boolean { + return name.kind === SyntaxKind.Identifier && + isTypeDeclaration(name.parent) && + getNameOfDeclaration(name.parent) === name; + } + + // True if the given identifier is part of a type reference + function isTypeReferenceIdentifier(node: EntityName): boolean { + while (node.parent.kind === SyntaxKind.QualifiedName) { + node = node.parent as QualifiedName; + } + + return node.parent.kind === SyntaxKind.TypeReference; + } + + function isInNameOfExpressionWithTypeArguments(node: Node): boolean { + while (node.parent.kind === SyntaxKind.PropertyAccessExpression) { + node = node.parent; + } + + return node.parent.kind === SyntaxKind.ExpressionWithTypeArguments; + } + + function forEachEnclosingClass(node: Node, callback: (node: ClassLikeDeclaration) => T | undefined): T | undefined { + let result: T | undefined; + let containingClass = getContainingClass(node); + while (containingClass) { + if (result = callback(containingClass)) break; + containingClass = getContainingClass(containingClass); + } + + return result; + } + + function isNodeUsedDuringClassInitialization(node: Node) { + return !!findAncestor(node, element => { + if (isConstructorDeclaration(element) && nodeIsPresent(element.body) || isPropertyDeclaration(element)) { + return true; + } + else if (isClassLike(element) || isFunctionLikeDeclaration(element)) { + return "quit"; + } + + return false; + }); + } + + function isNodeWithinClass(node: Node, classDeclaration: ClassLikeDeclaration) { + return !!forEachEnclosingClass(node, n => n === classDeclaration); + } + + function getLeftSideOfImportEqualsOrExportAssignment(nodeOnRightSide: EntityName): ImportEqualsDeclaration | ExportAssignment | undefined { + while (nodeOnRightSide.parent.kind === SyntaxKind.QualifiedName) { + nodeOnRightSide = nodeOnRightSide.parent as QualifiedName; + } + + if (nodeOnRightSide.parent.kind === SyntaxKind.ImportEqualsDeclaration) { + return (nodeOnRightSide.parent as ImportEqualsDeclaration).moduleReference === nodeOnRightSide ? nodeOnRightSide.parent as ImportEqualsDeclaration : undefined; + } + + if (nodeOnRightSide.parent.kind === SyntaxKind.ExportAssignment) { + return (nodeOnRightSide.parent as ExportAssignment).expression === nodeOnRightSide as Node ? nodeOnRightSide.parent as ExportAssignment : undefined; + } + + return undefined; + } + + function isInRightSideOfImportOrExportAssignment(node: EntityName) { + return getLeftSideOfImportEqualsOrExportAssignment(node) !== undefined; + } + + function getSpecialPropertyAssignmentSymbolFromEntityName(entityName: EntityName | PropertyAccessExpression) { + const specialPropertyAssignmentKind = getAssignmentDeclarationKind(entityName.parent.parent as BinaryExpression); + switch (specialPropertyAssignmentKind) { + case AssignmentDeclarationKind.ExportsProperty: + case AssignmentDeclarationKind.PrototypeProperty: + return getSymbolOfNode(entityName.parent); + case AssignmentDeclarationKind.Property: + if (isPropertyAccessExpression(entityName.parent) && getLeftmostAccessExpression(entityName.parent) === entityName) { + return undefined; + } + // falls through + case AssignmentDeclarationKind.ThisProperty: + case AssignmentDeclarationKind.ModuleExports: + return getSymbolOfDeclaration(entityName.parent.parent as BinaryExpression); + } + } + + function isImportTypeQualifierPart(node: EntityName): ImportTypeNode | undefined { + let parent = node.parent; + while (isQualifiedName(parent)) { + node = parent; + parent = parent.parent; + } + if (parent && parent.kind === SyntaxKind.ImportType && (parent as ImportTypeNode).qualifier === node) { + return parent as ImportTypeNode; + } + return undefined; + } + + function isThisPropertyAndThisTyped(node: PropertyAccessExpression) { + if (node.expression.kind === SyntaxKind.ThisKeyword) { + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (isFunctionLike(container)) { + const containingLiteral = getContainingObjectLiteral(container); + if (containingLiteral) { + const contextualType = getApparentTypeOfContextualType(containingLiteral, /*contextFlags*/ undefined); + const type = getThisTypeOfObjectLiteralFromContextualType(containingLiteral, contextualType); + return type && !isTypeAny(type); + } + } + } + } + + function getSymbolOfNameOrPropertyAccessExpression(name: EntityName | PrivateIdentifier | PropertyAccessExpression | JSDocMemberName): Symbol | undefined { + if (isDeclarationName(name)) { + return getSymbolOfNode(name.parent); + } + + if ( + isInJSFile(name) && + name.parent.kind === SyntaxKind.PropertyAccessExpression && + name.parent === (name.parent.parent as BinaryExpression).left + ) { + // Check if this is a special property assignment + if (!isPrivateIdentifier(name) && !isJSDocMemberName(name) && !isThisPropertyAndThisTyped(name.parent as PropertyAccessExpression)) { + const specialPropertyAssignmentSymbol = getSpecialPropertyAssignmentSymbolFromEntityName(name); + if (specialPropertyAssignmentSymbol) { + return specialPropertyAssignmentSymbol; + } + } + } + + if (name.parent.kind === SyntaxKind.ExportAssignment && isEntityNameExpression(name)) { + // Even an entity name expression that doesn't resolve as an entityname may still typecheck as a property access expression + const success = resolveEntityName(name, /*all meanings*/ SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*ignoreErrors*/ true); + if (success && success !== unknownSymbol) { + return success; + } + } + else if (isEntityName(name) && isInRightSideOfImportOrExportAssignment(name)) { + // Since we already checked for ExportAssignment, this really could only be an Import + const importEqualsDeclaration = getAncestor(name, SyntaxKind.ImportEqualsDeclaration); + Debug.assert(importEqualsDeclaration !== undefined); + return getSymbolOfPartOfRightHandSideOfImportEquals(name, /*dontResolveAlias*/ true); + } + + if (isEntityName(name)) { + const possibleImportNode = isImportTypeQualifierPart(name); + if (possibleImportNode) { + getTypeFromTypeNode(possibleImportNode); + const sym = getNodeLinks(name).resolvedSymbol; + return sym === unknownSymbol ? undefined : sym; + } + } + + while (isRightSideOfQualifiedNameOrPropertyAccessOrJSDocMemberName(name)) { + name = name.parent as QualifiedName | PropertyAccessEntityNameExpression | JSDocMemberName; + } + + if (isInNameOfExpressionWithTypeArguments(name)) { + let meaning = SymbolFlags.None; + if (name.parent.kind === SyntaxKind.ExpressionWithTypeArguments) { + // An 'ExpressionWithTypeArguments' may appear in type space (interface Foo extends Bar), + // value space (return foo), or both(class Foo extends Bar); ensure the meaning matches. + meaning = isPartOfTypeNode(name) ? SymbolFlags.Type : SymbolFlags.Value; + + // In a class 'extends' clause we are also looking for a value. + if (isExpressionWithTypeArgumentsInClassExtendsClause(name.parent)) { + meaning |= SymbolFlags.Value; + } + } + else { + meaning = SymbolFlags.Namespace; + } + + meaning |= SymbolFlags.Alias; + const entityNameSymbol = isEntityNameExpression(name) ? resolveEntityName(name, meaning, /*ignoreErrors*/ true) : undefined; + if (entityNameSymbol) { + return entityNameSymbol; + } + } + + if (name.parent.kind === SyntaxKind.JSDocParameterTag) { + return getParameterSymbolFromJSDoc(name.parent as JSDocParameterTag); + } + + if (name.parent.kind === SyntaxKind.TypeParameter && name.parent.parent.kind === SyntaxKind.JSDocTemplateTag) { + Debug.assert(!isInJSFile(name)); // Otherwise `isDeclarationName` would have been true. + const typeParameter = getTypeParameterFromJsDoc(name.parent as TypeParameterDeclaration & { parent: JSDocTemplateTag; }); + return typeParameter && typeParameter.symbol; + } + + if (isExpressionNode(name)) { + if (nodeIsMissing(name)) { + // Missing entity name. + return undefined; + } + + const isJSDoc = findAncestor(name, or(isJSDocLinkLike, isJSDocNameReference, isJSDocMemberName)); + const meaning = isJSDoc ? SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Value : SymbolFlags.Value; + if (name.kind === SyntaxKind.Identifier) { + if (isJSXTagName(name) && isJsxIntrinsicTagName(name)) { + const symbol = getIntrinsicTagSymbol(name.parent as JsxOpeningLikeElement); + return symbol === unknownSymbol ? undefined : symbol; + } + const result = resolveEntityName(name, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, getHostSignatureFromJSDoc(name)); + if (!result && isJSDoc) { + const container = findAncestor(name, or(isClassLike, isInterfaceDeclaration)); + if (container) { + return resolveJSDocMemberName(name, /*ignoreErrors*/ true, getSymbolOfDeclaration(container)); + } + } + if (result && isJSDoc) { + const container = getJSDocHost(name); + if (container && isEnumMember(container) && container === result.valueDeclaration) { + return resolveEntityName(name, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, getSourceFileOfNode(container)) || result; + } + } + return result; + } + else if (isPrivateIdentifier(name)) { + return getSymbolForPrivateIdentifierExpression(name); + } + else if (name.kind === SyntaxKind.PropertyAccessExpression || name.kind === SyntaxKind.QualifiedName) { + const links = getNodeLinks(name); + if (links.resolvedSymbol) { + return links.resolvedSymbol; + } + + if (name.kind === SyntaxKind.PropertyAccessExpression) { + checkPropertyAccessExpression(name, CheckMode.Normal); + if (!links.resolvedSymbol) { + links.resolvedSymbol = getApplicableIndexSymbol(checkExpressionCached(name.expression), getLiteralTypeFromPropertyName(name.name)); + } + } + else { + checkQualifiedName(name, CheckMode.Normal); + } + if (!links.resolvedSymbol && isJSDoc && isQualifiedName(name)) { + return resolveJSDocMemberName(name); + } + return links.resolvedSymbol; + } + else if (isJSDocMemberName(name)) { + return resolveJSDocMemberName(name); + } + } + else if (isTypeReferenceIdentifier(name as EntityName)) { + const meaning = name.parent.kind === SyntaxKind.TypeReference ? SymbolFlags.Type : SymbolFlags.Namespace; + const symbol = resolveEntityName(name as EntityName, meaning, /*ignoreErrors*/ false, /*dontResolveAlias*/ true); + return symbol && symbol !== unknownSymbol ? symbol : getUnresolvedSymbolForEntityName(name as EntityName); + } + if (name.parent.kind === SyntaxKind.TypePredicate) { + return resolveEntityName(name as Identifier, /*meaning*/ SymbolFlags.FunctionScopedVariable); + } + + return undefined; + } + + function getApplicableIndexSymbol(type: Type, keyType: Type) { + const infos = getApplicableIndexInfos(type, keyType); + if (infos.length && (type as ObjectType).members) { + const symbol = getIndexSymbolFromSymbolTable(resolveStructuredTypeMembers(type as ObjectType).members); + if (infos === getIndexInfosOfType(type)) { + return symbol; + } + else if (symbol) { + const symbolLinks = getSymbolLinks(symbol); + const declarationList = mapDefined(infos, i => i.declaration); + const nodeListId = map(declarationList, getNodeId).join(","); + if (!symbolLinks.filteredIndexSymbolCache) { + symbolLinks.filteredIndexSymbolCache = new Map(); + } + if (symbolLinks.filteredIndexSymbolCache.has(nodeListId)) { + return symbolLinks.filteredIndexSymbolCache.get(nodeListId)!; + } + else { + const copy = createSymbol(SymbolFlags.Signature, InternalSymbolName.Index); + copy.declarations = mapDefined(infos, i => i.declaration); + copy.parent = type.aliasSymbol ? type.aliasSymbol : type.symbol ? type.symbol : getSymbolAtLocation(copy.declarations[0].parent); + symbolLinks.filteredIndexSymbolCache.set(nodeListId, copy); + return copy; + } + } + } + } + + /** + * Recursively resolve entity names and jsdoc instance references: + * 1. K#m as K.prototype.m for a class (or other value) K + * 2. K.m as K.prototype.m + * 3. I.m as I.m for a type I, or any other I.m that fails to resolve in (1) or (2) + * + * For unqualified names, a container K may be provided as a second argument. + */ + function resolveJSDocMemberName(name: EntityName | JSDocMemberName, ignoreErrors?: boolean, container?: Symbol): Symbol | undefined { + if (isEntityName(name)) { + // resolve static values first + const meaning = SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Value; + let symbol = resolveEntityName(name, meaning, ignoreErrors, /*dontResolveAlias*/ true, getHostSignatureFromJSDoc(name)); + if (!symbol && isIdentifier(name) && container) { + symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(container), name.escapedText, meaning)); + } + if (symbol) { + return symbol; + } + } + const left = isIdentifier(name) ? container : resolveJSDocMemberName(name.left, ignoreErrors, container); + const right = isIdentifier(name) ? name.escapedText : name.right.escapedText; + if (left) { + const proto = left.flags & SymbolFlags.Value && getPropertyOfType(getTypeOfSymbol(left), "prototype" as __String); + const t = proto ? getTypeOfSymbol(proto) : getDeclaredTypeOfSymbol(left); + return getPropertyOfType(t, right); + } + } + + function getSymbolAtLocation(node: Node, ignoreErrors?: boolean): Symbol | undefined { + if (isSourceFile(node)) { + return isExternalModule(node) ? getMergedSymbol(node.symbol) : undefined; + } + const { parent } = node; + const grandParent = parent.parent; + + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return undefined; + } + + if (isDeclarationNameOrImportPropertyName(node)) { + // This is a declaration, call getSymbolOfNode + const parentSymbol = getSymbolOfDeclaration(parent as Declaration); + return isImportOrExportSpecifier(node.parent) && node.parent.propertyName === node + ? getImmediateAliasedSymbol(parentSymbol) + : parentSymbol; + } + else if (isLiteralComputedPropertyDeclarationName(node)) { + return getSymbolOfDeclaration(parent.parent as Declaration); + } + + if (node.kind === SyntaxKind.Identifier) { + if (isInRightSideOfImportOrExportAssignment(node as Identifier)) { + return getSymbolOfNameOrPropertyAccessExpression(node as Identifier); + } + else if ( + parent.kind === SyntaxKind.BindingElement && + grandParent.kind === SyntaxKind.ObjectBindingPattern && + node === (parent as BindingElement).propertyName + ) { + const typeOfPattern = getTypeOfNode(grandParent); + const propertyDeclaration = getPropertyOfType(typeOfPattern, (node as Identifier).escapedText); + + if (propertyDeclaration) { + return propertyDeclaration; + } + } + else if (isMetaProperty(parent) && parent.name === node) { + if (parent.keywordToken === SyntaxKind.NewKeyword && idText(node as Identifier) === "target") { + // `target` in `new.target` + return checkNewTargetMetaProperty(parent).symbol; + } + // The `meta` in `import.meta` could be given `getTypeOfNode(parent).symbol` (the `ImportMeta` interface symbol), but + // we have a fake expression type made for other reasons already, whose transient `meta` + // member should more exactly be the kind of (declarationless) symbol we want. + // (See #44364 and #45031 for relevant implementation PRs) + if (parent.keywordToken === SyntaxKind.ImportKeyword && idText(node as Identifier) === "meta") { + return getGlobalImportMetaExpressionType().members!.get("meta" as __String); + } + // no other meta properties are valid syntax, thus no others should have symbols + return undefined; + } + } + + switch (node.kind) { + case SyntaxKind.Identifier: + case SyntaxKind.PrivateIdentifier: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.QualifiedName: + if (!isThisInTypeQuery(node)) { + return getSymbolOfNameOrPropertyAccessExpression(node as EntityName | PrivateIdentifier | PropertyAccessExpression); + } + // falls through + + case SyntaxKind.ThisKeyword: + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (isFunctionLike(container)) { + const sig = getSignatureFromDeclaration(container); + if (sig.thisParameter) { + return sig.thisParameter; + } + } + if (isInExpressionContext(node)) { + return checkExpression(node as Expression).symbol; + } + // falls through + + case SyntaxKind.ThisType: + return getTypeFromThisTypeNode(node as ThisExpression | ThisTypeNode).symbol; + + case SyntaxKind.SuperKeyword: + return checkExpression(node as Expression).symbol; + + case SyntaxKind.ConstructorKeyword: + // constructor keyword for an overload, should take us to the definition if it exist + const constructorDeclaration = node.parent; + if (constructorDeclaration && constructorDeclaration.kind === SyntaxKind.Constructor) { + return (constructorDeclaration.parent as ClassDeclaration).symbol; + } + return undefined; + + case SyntaxKind.StringLiteral: + case SyntaxKind.NoSubstitutionTemplateLiteral: + // 1). import x = require("./mo/*gotToDefinitionHere*/d") + // 2). External module name in an import declaration + // 3). Dynamic import call or require in javascript + // 4). type A = import("./f/*gotToDefinitionHere*/oo") + if ( + (isExternalModuleImportEqualsDeclaration(node.parent.parent) && getExternalModuleImportEqualsDeclarationExpression(node.parent.parent) === node) || + ((node.parent.kind === SyntaxKind.ImportDeclaration || node.parent.kind === SyntaxKind.ExportDeclaration) && (node.parent as ImportDeclaration).moduleSpecifier === node) || + (isInJSFile(node) && isJSDocImportTag(node.parent) && node.parent.moduleSpecifier === node) || + ((isInJSFile(node) && isRequireCall(node.parent, /*requireStringLiteralLikeArgument*/ false)) || isImportCall(node.parent)) || + (isLiteralTypeNode(node.parent) && isLiteralImportTypeNode(node.parent.parent) && node.parent.parent.argument === node.parent) + ) { + return resolveExternalModuleName(node, node as LiteralExpression, ignoreErrors); + } + if (isCallExpression(parent) && isBindableObjectDefinePropertyCall(parent) && parent.arguments[1] === node) { + return getSymbolOfDeclaration(parent); + } + // falls through + + case SyntaxKind.NumericLiteral: + // index access + const objectType = isElementAccessExpression(parent) + ? parent.argumentExpression === node ? getTypeOfExpression(parent.expression) : undefined + : isLiteralTypeNode(parent) && isIndexedAccessTypeNode(grandParent) + ? getTypeFromTypeNode(grandParent.objectType) + : undefined; + return objectType && getPropertyOfType(objectType, escapeLeadingUnderscores((node as StringLiteral | NumericLiteral).text)); + + case SyntaxKind.DefaultKeyword: + case SyntaxKind.FunctionKeyword: + case SyntaxKind.EqualsGreaterThanToken: + case SyntaxKind.ClassKeyword: + return getSymbolOfNode(node.parent); + case SyntaxKind.ImportType: + return isLiteralImportTypeNode(node) ? getSymbolAtLocation(node.argument.literal, ignoreErrors) : undefined; + + case SyntaxKind.ExportKeyword: + return isExportAssignment(node.parent) ? Debug.checkDefined(node.parent.symbol) : undefined; + + case SyntaxKind.ImportKeyword: + case SyntaxKind.NewKeyword: + return isMetaProperty(node.parent) ? checkMetaPropertyKeyword(node.parent).symbol : undefined; + case SyntaxKind.InstanceOfKeyword: + if (isBinaryExpression(node.parent)) { + const type = getTypeOfExpression(node.parent.right); + const hasInstanceMethodType = getSymbolHasInstanceMethodOfObjectType(type); + return hasInstanceMethodType?.symbol ?? type.symbol; + } + return undefined; + case SyntaxKind.MetaProperty: + return checkExpression(node as Expression).symbol; + case SyntaxKind.JsxNamespacedName: + if (isJSXTagName(node) && isJsxIntrinsicTagName(node)) { + const symbol = getIntrinsicTagSymbol(node.parent as JsxOpeningLikeElement); + return symbol === unknownSymbol ? undefined : symbol; + } + // falls through + + default: + return undefined; + } + } + + function getIndexInfosAtLocation(node: Node): readonly IndexInfo[] | undefined { + if (isIdentifier(node) && isPropertyAccessExpression(node.parent) && node.parent.name === node) { + const keyType = getLiteralTypeFromPropertyName(node); + const objectType = getTypeOfExpression(node.parent.expression); + const objectTypes = objectType.flags & TypeFlags.Union ? (objectType as UnionType).types : [objectType]; + return flatMap(objectTypes, t => filter(getIndexInfosOfType(t), info => isApplicableIndexType(keyType, info.keyType))); + } + return undefined; + } + + function getShorthandAssignmentValueSymbol(location: Node | undefined): Symbol | undefined { + if (location && location.kind === SyntaxKind.ShorthandPropertyAssignment) { + return resolveEntityName((location as ShorthandPropertyAssignment).name, SymbolFlags.Value | SymbolFlags.Alias); + } + return undefined; + } + + /** Returns the target of an export specifier without following aliases */ + function getExportSpecifierLocalTargetSymbol(node: ExportSpecifier | Identifier): Symbol | undefined { + if (isExportSpecifier(node)) { + const name = node.propertyName || node.name; + return node.parent.parent.moduleSpecifier ? + getExternalModuleMember(node.parent.parent, node) : + name.kind === SyntaxKind.StringLiteral ? undefined : // Skip for invalid syntax like this: export { "x" } + resolveEntityName(name, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); + } + else { + return resolveEntityName(node, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); + } + } + + function getTypeOfNode(node: Node): Type { + if (isSourceFile(node) && !isExternalModule(node)) { + return errorType; + } + + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return errorType; + } + + const classDecl = tryGetClassImplementingOrExtendingExpressionWithTypeArguments(node); + const classType = classDecl && getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(classDecl.class)); + if (isPartOfTypeNode(node)) { + const typeFromTypeNode = getTypeFromTypeNode(node as TypeNode); + return classType ? getTypeWithThisArgument(typeFromTypeNode, classType.thisType) : typeFromTypeNode; + } + + if (isExpressionNode(node)) { + return getRegularTypeOfExpression(node as Expression); + } + + if (classType && !classDecl.isImplements) { + // A SyntaxKind.ExpressionWithTypeArguments is considered a type node, except when it occurs in the + // extends clause of a class. We handle that case here. + const baseType = firstOrUndefined(getBaseTypes(classType)); + return baseType ? getTypeWithThisArgument(baseType, classType.thisType) : errorType; + } + + if (isTypeDeclaration(node)) { + // In this case, we call getSymbolOfNode instead of getSymbolAtLocation because it is a declaration + const symbol = getSymbolOfDeclaration(node); + return getDeclaredTypeOfSymbol(symbol); + } + + if (isTypeDeclarationName(node)) { + const symbol = getSymbolAtLocation(node); + return symbol ? getDeclaredTypeOfSymbol(symbol) : errorType; + } + + if (isBindingElement(node)) { + return getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ true, CheckMode.Normal) || errorType; + } + + if (isDeclaration(node)) { + // In this case, we call getSymbolOfNode instead of getSymbolAtLocation because it is a declaration + const symbol = getSymbolOfDeclaration(node); + return symbol ? getTypeOfSymbol(symbol) : errorType; + } + + if (isDeclarationNameOrImportPropertyName(node)) { + const symbol = getSymbolAtLocation(node); + if (symbol) { + return getTypeOfSymbol(symbol); + } + return errorType; + } + + if (isBindingPattern(node)) { + return getTypeForVariableLikeDeclaration(node.parent, /*includeOptionality*/ true, CheckMode.Normal) || errorType; + } + + if (isInRightSideOfImportOrExportAssignment(node as Identifier)) { + const symbol = getSymbolAtLocation(node); + if (symbol) { + const declaredType = getDeclaredTypeOfSymbol(symbol); + return !isErrorType(declaredType) ? declaredType : getTypeOfSymbol(symbol); + } + } + + if (isMetaProperty(node.parent) && node.parent.keywordToken === node.kind) { + return checkMetaPropertyKeyword(node.parent); + } + + if (isImportAttributes(node)) { + return getGlobalImportAttributesType(/*reportErrors*/ false); + } + + return errorType; + } + + // Gets the type of object literal or array literal of destructuring assignment. + // { a } from + // for ( { a } of elems) { + // } + // [ a ] from + // [a] = [ some array ...] + function getTypeOfAssignmentPattern(expr: AssignmentPattern): Type | undefined { + Debug.assert(expr.kind === SyntaxKind.ObjectLiteralExpression || expr.kind === SyntaxKind.ArrayLiteralExpression); + // If this is from "for of" + // for ( { a } of elems) { + // } + if (expr.parent.kind === SyntaxKind.ForOfStatement) { + const iteratedType = checkRightHandSideOfForOf(expr.parent as ForOfStatement); + return checkDestructuringAssignment(expr, iteratedType || errorType); + } + // If this is from "for" initializer + // for ({a } = elems[0];.....) { } + if (expr.parent.kind === SyntaxKind.BinaryExpression) { + const iteratedType = getTypeOfExpression((expr.parent as BinaryExpression).right); + return checkDestructuringAssignment(expr, iteratedType || errorType); + } + // If this is from nested object binding pattern + // for ({ skills: { primary, secondary } } = multiRobot, i = 0; i < 1; i++) { + if (expr.parent.kind === SyntaxKind.PropertyAssignment) { + const node = cast(expr.parent.parent, isObjectLiteralExpression); + const typeOfParentObjectLiteral = getTypeOfAssignmentPattern(node) || errorType; + const propertyIndex = indexOfNode(node.properties, expr.parent); + return checkObjectLiteralDestructuringPropertyAssignment(node, typeOfParentObjectLiteral, propertyIndex); + } + // Array literal assignment - array destructuring pattern + const node = cast(expr.parent, isArrayLiteralExpression); + // [{ property1: p1, property2 }] = elems; + const typeOfArrayLiteral = getTypeOfAssignmentPattern(node) || errorType; + const elementType = checkIteratedTypeOrElementType(IterationUse.Destructuring, typeOfArrayLiteral, undefinedType, expr.parent) || errorType; + return checkArrayLiteralDestructuringElementAssignment(node, typeOfArrayLiteral, node.elements.indexOf(expr), elementType); + } + + // Gets the property symbol corresponding to the property in destructuring assignment + // 'property1' from + // for ( { property1: a } of elems) { + // } + // 'property1' at location 'a' from: + // [a] = [ property1, property2 ] + function getPropertySymbolOfDestructuringAssignment(location: Identifier) { + // Get the type of the object or array literal and then look for property of given name in the type + const typeOfObjectLiteral = getTypeOfAssignmentPattern(cast(location.parent.parent, isAssignmentPattern)); + return typeOfObjectLiteral && getPropertyOfType(typeOfObjectLiteral, location.escapedText); + } + + function getRegularTypeOfExpression(expr: Expression): Type { + if (isRightSideOfQualifiedNameOrPropertyAccess(expr)) { + expr = expr.parent as Expression; + } + return getRegularTypeOfLiteralType(getTypeOfExpression(expr)); + } + + /** + * Gets either the static or instance type of a class element, based on + * whether the element is declared as "static". + */ + function getParentTypeOfClassElement(node: ClassElement) { + const classSymbol = getSymbolOfNode(node.parent)!; + return isStatic(node) + ? getTypeOfSymbol(classSymbol) + : getDeclaredTypeOfSymbol(classSymbol); + } + + function getClassElementPropertyKeyType(element: ClassElement) { + const name = element.name!; + switch (name.kind) { + case SyntaxKind.Identifier: + return getStringLiteralType(idText(name)); + case SyntaxKind.NumericLiteral: + case SyntaxKind.StringLiteral: + return getStringLiteralType(name.text); + case SyntaxKind.ComputedPropertyName: + const nameType = checkComputedPropertyName(name); + return isTypeAssignableToKind(nameType, TypeFlags.ESSymbolLike) ? nameType : stringType; + default: + return Debug.fail("Unsupported property name."); + } + } + + // Return the list of properties of the given type, augmented with properties from Function + // if the type has call or construct signatures + function getAugmentedPropertiesOfType(type: Type): Symbol[] { + type = getApparentType(type); + const propsByName = createSymbolTable(getPropertiesOfType(type)); + const functionType = getSignaturesOfType(type, SignatureKind.Call).length ? globalCallableFunctionType : + getSignaturesOfType(type, SignatureKind.Construct).length ? globalNewableFunctionType : + undefined; + if (functionType) { + forEach(getPropertiesOfType(functionType), p => { + if (!propsByName.has(p.escapedName)) { + propsByName.set(p.escapedName, p); + } + }); + } + return getNamedMembers(propsByName); + } + + function typeHasCallOrConstructSignatures(type: Type): boolean { + return getSignaturesOfType(type, SignatureKind.Call).length !== 0 || getSignaturesOfType(type, SignatureKind.Construct).length !== 0; + } + + function getRootSymbols(symbol: Symbol): readonly Symbol[] { + const roots = getImmediateRootSymbols(symbol); + return roots ? flatMap(roots, getRootSymbols) : [symbol]; + } + function getImmediateRootSymbols(symbol: Symbol): readonly Symbol[] | undefined { + if (getCheckFlags(symbol) & CheckFlags.Synthetic) { + return mapDefined(getSymbolLinks(symbol).containingType!.types, type => getPropertyOfType(type, symbol.escapedName)); + } + else if (symbol.flags & SymbolFlags.Transient) { + const { links: { leftSpread, rightSpread, syntheticOrigin } } = symbol as TransientSymbol; + return leftSpread ? [leftSpread, rightSpread!] + : syntheticOrigin ? [syntheticOrigin] + : singleElementArray(tryGetTarget(symbol)); + } + return undefined; + } + function tryGetTarget(symbol: Symbol): Symbol | undefined { + let target: Symbol | undefined; + let next: Symbol | undefined = symbol; + while (next = getSymbolLinks(next).target) { + target = next; + } + return target; + } + + // Emitter support + + function isArgumentsLocalBinding(nodeIn: Identifier): boolean { + // Note: does not handle isShorthandPropertyAssignment (and probably a few more) + if (isGeneratedIdentifier(nodeIn)) return false; + const node = getParseTreeNode(nodeIn, isIdentifier); + if (!node) return false; + const parent = node.parent; + if (!parent) return false; + const isPropertyName = (isPropertyAccessExpression(parent) + || isPropertyAssignment(parent)) + && parent.name === node; + return !isPropertyName && getReferencedValueSymbol(node) === argumentsSymbol; + } + + function isNameOfModuleOrEnumDeclaration(node: Identifier) { + return isModuleOrEnumDeclaration(node.parent) && node === node.parent.name; + } + + // When resolved as an expression identifier, if the given node references an exported entity, return the declaration + // node of the exported entity's container. Otherwise, return undefined. + function getReferencedExportContainer(nodeIn: Identifier, prefixLocals?: boolean): SourceFile | ModuleDeclaration | EnumDeclaration | undefined { + const node = getParseTreeNode(nodeIn, isIdentifier); + if (node) { + // When resolving the export container for the name of a module or enum + // declaration, we need to start resolution at the declaration's container. + // Otherwise, we could incorrectly resolve the export container as the + // declaration if it contains an exported member with the same name. + let symbol = getReferencedValueSymbol(node, /*startInDeclarationContainer*/ isNameOfModuleOrEnumDeclaration(node)); + if (symbol) { + if (symbol.flags & SymbolFlags.ExportValue) { + // If we reference an exported entity within the same module declaration, then whether + // we prefix depends on the kind of entity. SymbolFlags.ExportHasLocal encompasses all the + // kinds that we do NOT prefix. + const exportSymbol = getMergedSymbol(symbol.exportSymbol!); + if (!prefixLocals && exportSymbol.flags & SymbolFlags.ExportHasLocal && !(exportSymbol.flags & SymbolFlags.Variable)) { + return undefined; + } + symbol = exportSymbol; + } + const parentSymbol = getParentOfSymbol(symbol); + if (parentSymbol) { + if (parentSymbol.flags & SymbolFlags.ValueModule && parentSymbol.valueDeclaration?.kind === SyntaxKind.SourceFile) { + const symbolFile = parentSymbol.valueDeclaration as SourceFile; + const referenceFile = getSourceFileOfNode(node); + // If `node` accesses an export and that export isn't in the same file, then symbol is a namespace export, so return undefined. + const symbolIsUmdExport = symbolFile !== referenceFile; + return symbolIsUmdExport ? undefined : symbolFile; + } + return findAncestor(node.parent, (n): n is ModuleDeclaration | EnumDeclaration => isModuleOrEnumDeclaration(n) && getSymbolOfDeclaration(n) === parentSymbol); + } + } + } + } + + // When resolved as an expression identifier, if the given node references an import, return the declaration of + // that import. Otherwise, return undefined. + function getReferencedImportDeclaration(nodeIn: Identifier): Declaration | undefined { + const specifier = getIdentifierGeneratedImportReference(nodeIn); + if (specifier) { + return specifier; + } + const node = getParseTreeNode(nodeIn, isIdentifier); + if (node) { + const symbol = getReferencedValueOrAliasSymbol(node); + + // We should only get the declaration of an alias if there isn't a local value + // declaration for the symbol + if (isNonLocalAlias(symbol, /*excludes*/ SymbolFlags.Value) && !getTypeOnlyAliasDeclaration(symbol, SymbolFlags.Value)) { + return getDeclarationOfAliasSymbol(symbol); + } + } + + return undefined; + } + + function isSymbolOfDestructuredElementOfCatchBinding(symbol: Symbol) { + return symbol.valueDeclaration + && isBindingElement(symbol.valueDeclaration) + && walkUpBindingElementsAndPatterns(symbol.valueDeclaration).parent.kind === SyntaxKind.CatchClause; + } + + function isSymbolOfDeclarationWithCollidingName(symbol: Symbol): boolean { + if (symbol.flags & SymbolFlags.BlockScoped && symbol.valueDeclaration && !isSourceFile(symbol.valueDeclaration)) { + const links = getSymbolLinks(symbol); + if (links.isDeclarationWithCollidingName === undefined) { + const container = getEnclosingBlockScopeContainer(symbol.valueDeclaration); + if (isStatementWithLocals(container) || isSymbolOfDestructuredElementOfCatchBinding(symbol)) { + if (resolveName(container.parent, symbol.escapedName, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)) { + // redeclaration - always should be renamed + links.isDeclarationWithCollidingName = true; + } + else if (hasNodeCheckFlag(symbol.valueDeclaration, NodeCheckFlags.CapturedBlockScopedBinding)) { + // binding is captured in the function + // should be renamed if: + // - binding is not top level - top level bindings never collide with anything + // AND + // - binding is not declared in loop, should be renamed to avoid name reuse across siblings + // let a, b + // { let x = 1; a = () => x; } + // { let x = 100; b = () => x; } + // console.log(a()); // should print '1' + // console.log(b()); // should print '100' + // OR + // - binding is declared inside loop but not in inside initializer of iteration statement or directly inside loop body + // * variables from initializer are passed to rewritten loop body as parameters so they are not captured directly + // * variables that are declared immediately in loop body will become top level variable after loop is rewritten and thus + // they will not collide with anything + const isDeclaredInLoop = hasNodeCheckFlag(symbol.valueDeclaration, NodeCheckFlags.BlockScopedBindingInLoop); + const inLoopInitializer = isIterationStatement(container, /*lookInLabeledStatements*/ false); + const inLoopBodyBlock = container.kind === SyntaxKind.Block && isIterationStatement(container.parent, /*lookInLabeledStatements*/ false); + + links.isDeclarationWithCollidingName = !isBlockScopedContainerTopLevel(container) && (!isDeclaredInLoop || (!inLoopInitializer && !inLoopBodyBlock)); + } + else { + links.isDeclarationWithCollidingName = false; + } + } + } + return links.isDeclarationWithCollidingName!; + } + return false; + } + + // When resolved as an expression identifier, if the given node references a nested block scoped entity with + // a name that either hides an existing name or might hide it when compiled downlevel, + // return the declaration of that entity. Otherwise, return undefined. + function getReferencedDeclarationWithCollidingName(nodeIn: Identifier): Declaration | undefined { + if (!isGeneratedIdentifier(nodeIn)) { + const node = getParseTreeNode(nodeIn, isIdentifier); + if (node) { + const symbol = getReferencedValueSymbol(node); + if (symbol && isSymbolOfDeclarationWithCollidingName(symbol)) { + return symbol.valueDeclaration; + } + } + } + + return undefined; + } + + // Return true if the given node is a declaration of a nested block scoped entity with a name that either hides an + // existing name or might hide a name when compiled downlevel + function isDeclarationWithCollidingName(nodeIn: Declaration): boolean { + const node = getParseTreeNode(nodeIn, isDeclaration); + if (node) { + const symbol = getSymbolOfDeclaration(node); + if (symbol) { + return isSymbolOfDeclarationWithCollidingName(symbol); + } + } + + return false; + } + + function isValueAliasDeclaration(node: Node): boolean { + Debug.assert(canCollectSymbolAliasAccessabilityData); + switch (node.kind) { + case SyntaxKind.ImportEqualsDeclaration: + return isAliasResolvedToValue(getSymbolOfDeclaration(node as ImportEqualsDeclaration)); + case SyntaxKind.ImportClause: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportSpecifier: + case SyntaxKind.ExportSpecifier: + const symbol = getSymbolOfDeclaration(node as ImportClause | NamespaceImport | ImportSpecifier | ExportSpecifier); + return !!symbol && isAliasResolvedToValue(symbol, /*excludeTypeOnlyValues*/ true); + case SyntaxKind.ExportDeclaration: + const exportClause = (node as ExportDeclaration).exportClause; + return !!exportClause && ( + isNamespaceExport(exportClause) || + some(exportClause.elements, isValueAliasDeclaration) + ); + case SyntaxKind.ExportAssignment: + return (node as ExportAssignment).expression && (node as ExportAssignment).expression.kind === SyntaxKind.Identifier ? + isAliasResolvedToValue(getSymbolOfDeclaration(node as ExportAssignment), /*excludeTypeOnlyValues*/ true) : + true; + } + return false; + } + + function isTopLevelValueImportEqualsWithEntityName(nodeIn: ImportEqualsDeclaration): boolean { + const node = getParseTreeNode(nodeIn, isImportEqualsDeclaration); + if (node === undefined || node.parent.kind !== SyntaxKind.SourceFile || !isInternalModuleImportEqualsDeclaration(node)) { + // parent is not source file or it is not reference to internal module + return false; + } + + const isValue = isAliasResolvedToValue(getSymbolOfDeclaration(node)); + return isValue && node.moduleReference && !nodeIsMissing(node.moduleReference); + } + + function isAliasResolvedToValue(symbol: Symbol | undefined, excludeTypeOnlyValues?: boolean): boolean { + if (!symbol) { + return false; + } + const container = getSourceFileOfNode(symbol.valueDeclaration); + const fileSymbol = container && getSymbolOfDeclaration(container); + // Ensures cjs export assignment is setup, since this symbol may point at, and merge with, the file itself. + // If we don't, the merge may not have yet occured, and the flags check below will be missing flags that + // are added as a result of the merge. + void resolveExternalModuleSymbol(fileSymbol); + const target = getExportSymbolOfValueSymbolIfExported(resolveAlias(symbol)); + if (target === unknownSymbol) { + return !excludeTypeOnlyValues || !getTypeOnlyAliasDeclaration(symbol); + } + // const enums and modules that contain only const enums are not considered values from the emit perspective + // unless 'preserveConstEnums' option is set to true + return !!(getSymbolFlags(symbol, excludeTypeOnlyValues, /*excludeLocalMeanings*/ true) & SymbolFlags.Value) && + (shouldPreserveConstEnums(compilerOptions) || !isConstEnumOrConstEnumOnlyModule(target)); + } + + function isConstEnumOrConstEnumOnlyModule(s: Symbol): boolean { + return isConstEnumSymbol(s) || !!s.constEnumOnlyModule; + } + + function isReferencedAliasDeclaration(node: Node, checkChildren?: boolean): boolean { + Debug.assert(canCollectSymbolAliasAccessabilityData); + if (isAliasSymbolDeclaration(node)) { + const symbol = getSymbolOfDeclaration(node as Declaration); + const links = symbol && getSymbolLinks(symbol); + if (links?.referenced) { + return true; + } + const target = getSymbolLinks(symbol).aliasTarget; + if ( + target && getEffectiveModifierFlags(node) & ModifierFlags.Export && + getSymbolFlags(target) & SymbolFlags.Value && + (shouldPreserveConstEnums(compilerOptions) || !isConstEnumOrConstEnumOnlyModule(target)) + ) { + // An `export import ... =` of a value symbol is always considered referenced + return true; + } + } + + if (checkChildren) { + return !!forEachChild(node, node => isReferencedAliasDeclaration(node, checkChildren)); + } + return false; + } + + function isImplementationOfOverload(node: SignatureDeclaration) { + if (nodeIsPresent((node as FunctionLikeDeclaration).body)) { + if (isGetAccessor(node) || isSetAccessor(node)) return false; // Get or set accessors can never be overload implementations, but can have up to 2 signatures + const symbol = getSymbolOfDeclaration(node); + const signaturesOfSymbol = getSignaturesOfSymbol(symbol); + // If this function body corresponds to function with multiple signature, it is implementation of overload + // e.g.: function foo(a: string): string; + // function foo(a: number): number; + // function foo(a: any) { // This is implementation of the overloads + // return a; + // } + return signaturesOfSymbol.length > 1 || + // If there is single signature for the symbol, it is overload if that signature isn't coming from the node + // e.g.: function foo(a: string): string; + // function foo(a: any) { // This is implementation of the overloads + // return a; + // } + (signaturesOfSymbol.length === 1 && signaturesOfSymbol[0].declaration !== node); + } + return false; + } + + function declaredParameterTypeContainsUndefined(parameter: ParameterDeclaration | JSDocParameterTag) { + const typeNode = getNonlocalEffectiveTypeAnnotationNode(parameter); + if (!typeNode) return false; + const type = getTypeFromTypeNode(typeNode); + return containsUndefinedType(type); + } + function requiresAddingImplicitUndefined(parameter: ParameterDeclaration | JSDocParameterTag) { + return (isRequiredInitializedParameter(parameter) || isOptionalUninitializedParameterProperty(parameter)) && !declaredParameterTypeContainsUndefined(parameter); + } + + function isRequiredInitializedParameter(parameter: ParameterDeclaration | JSDocParameterTag): boolean { + return !!strictNullChecks && + !isOptionalParameter(parameter) && + !isJSDocParameterTag(parameter) && + !!parameter.initializer && + !hasSyntacticModifier(parameter, ModifierFlags.ParameterPropertyModifier); + } + + function isOptionalUninitializedParameterProperty(parameter: ParameterDeclaration | JSDocParameterTag) { + return strictNullChecks && + isOptionalParameter(parameter) && + (isJSDocParameterTag(parameter) || !parameter.initializer) && + hasSyntacticModifier(parameter, ModifierFlags.ParameterPropertyModifier); + } + + function isExpandoFunctionDeclaration(node: Declaration): boolean { + const declaration = getParseTreeNode(node, (n): n is FunctionDeclaration | VariableDeclaration => isFunctionDeclaration(n) || isVariableDeclaration(n)); + if (!declaration) { + return false; + } + let symbol: Symbol | undefined; + if (isVariableDeclaration(declaration)) { + if (declaration.type || (!isInJSFile(declaration) && !isVarConstLike(declaration))) { + return false; + } + const initializer = getDeclaredExpandoInitializer(declaration); + if (!initializer || !canHaveSymbol(initializer)) { + return false; + } + symbol = getSymbolOfDeclaration(initializer); + } + else { + symbol = getSymbolOfDeclaration(declaration); + } + if (!symbol || !(symbol.flags & SymbolFlags.Function | SymbolFlags.Variable)) { + return false; + } + return !!forEachEntry(getExportsOfSymbol(symbol), p => p.flags & SymbolFlags.Value && isExpandoPropertyDeclaration(p.valueDeclaration)); + } + + function getPropertiesOfContainerFunction(node: Declaration): Symbol[] { + const declaration = getParseTreeNode(node, isFunctionDeclaration); + if (!declaration) { + return emptyArray; + } + const symbol = getSymbolOfDeclaration(declaration); + return symbol && getPropertiesOfType(getTypeOfSymbol(symbol)) || emptyArray; + } + + function getNodeCheckFlags(node: Node): NodeCheckFlags { + const nodeId = node.id || 0; + if (nodeId < 0 || nodeId >= nodeLinks.length) return 0; + return nodeLinks[nodeId]?.flags || 0; + } + + function hasNodeCheckFlag(node: Node, flag: LazyNodeCheckFlags) { + calculateNodeCheckFlagWorker(node, flag); + return !!(getNodeCheckFlags(node) & flag); + } + + function calculateNodeCheckFlagWorker(node: Node, flag: LazyNodeCheckFlags) { + if (!compilerOptions.noCheck && canIncludeBindAndCheckDiagnostics(getSourceFileOfNode(node), compilerOptions)) { + // Unless noCheck is passed, assume calculation of node check flags has been done eagerly. + // This saves needing to mark up where in the eager traversal certain results are "done", + // just to reconcile the eager and lazy results. This wouldn't be hard if an eager typecheck + // was actually an in-order traversal, but it isn't - some nodes are deferred, and so don't + // have these node check flags calculated until that deferral is completed. As an example, + // in concept, we could consider a class that we've called `checkSourceElement` on as having had + // these flags calculated, but since the method bodies are deferred, we actually can't set the + // flags as having been calculated until that deferral is completed. + // The downside to this either/or approach to eager or lazy calculation is that we can't combine + // a partial eager traversal and lazy calculation for the missing bits, and there's a bit of + // overlap in functionality. This isn't a huge loss for any usecases today, but would be nice + // alongside language service partial file checking and editor-triggered emit. + return; + } + const links = getNodeLinks(node); + if (links.calculatedFlags & flag) { + return; + } + // This is only the set of `NodeCheckFlags` our emitter actually looks for, not all of them + switch (flag) { + case NodeCheckFlags.SuperInstance: + case NodeCheckFlags.SuperStatic: + return checkSingleSuperExpression(node); + case NodeCheckFlags.MethodWithSuperPropertyAccessInAsync: + case NodeCheckFlags.MethodWithSuperPropertyAssignmentInAsync: + case NodeCheckFlags.ContainsSuperPropertyInStaticInitializer: + return checkChildSuperExpressions(node); + case NodeCheckFlags.CaptureArguments: + case NodeCheckFlags.ContainsCapturedBlockScopeBinding: + case NodeCheckFlags.NeedsLoopOutParameter: + case NodeCheckFlags.ContainsConstructorReference: + return checkChildIdentifiers(node); + case NodeCheckFlags.ConstructorReference: + return checkSingleIdentifier(node); + case NodeCheckFlags.LoopWithCapturedBlockScopedBinding: + case NodeCheckFlags.BlockScopedBindingInLoop: + case NodeCheckFlags.CapturedBlockScopedBinding: + return checkContainingBlockScopeBindingUses(node); + default: + return Debug.assertNever(flag, `Unhandled node check flag calculation: ${Debug.formatNodeCheckFlags(flag)}`); + } + + function forEachNodeRecursively(root: Node, cb: (node: Node, parent: Node) => T | "skip" | undefined): T | undefined { + const rootResult = cb(root, root.parent); + if (rootResult === "skip") return undefined; + if (rootResult) return rootResult; + return forEachChildRecursively(root, cb); + } + + function checkSuperExpressions(node: Node) { + const links = getNodeLinks(node); + if (links.calculatedFlags & flag) return "skip"; + links.calculatedFlags |= NodeCheckFlags.MethodWithSuperPropertyAccessInAsync | NodeCheckFlags.MethodWithSuperPropertyAssignmentInAsync | NodeCheckFlags.ContainsSuperPropertyInStaticInitializer; + checkSingleSuperExpression(node); + return undefined; + } + + function checkChildSuperExpressions(node: Node) { + forEachNodeRecursively(node, checkSuperExpressions); + } + + function checkSingleSuperExpression(node: Node) { + const nodeLinks = getNodeLinks(node); // This is called on sub-nodes of the original input, make sure we set `calculatedFlags` on the correct node + nodeLinks.calculatedFlags |= NodeCheckFlags.SuperInstance | NodeCheckFlags.SuperStatic; // Yes, we set this on non-applicable nodes, so we can entirely skip the traversal on future calls + if (node.kind === SyntaxKind.SuperKeyword) { + checkSuperExpression(node); + } + } + + function checkIdentifiers(node: Node) { + const links = getNodeLinks(node); + if (links.calculatedFlags & flag) return "skip"; + links.calculatedFlags |= NodeCheckFlags.CaptureArguments | NodeCheckFlags.ContainsCapturedBlockScopeBinding | NodeCheckFlags.NeedsLoopOutParameter | NodeCheckFlags.ContainsConstructorReference; + checkSingleIdentifier(node); + return undefined; + } + + function checkChildIdentifiers(node: Node) { + forEachNodeRecursively(node, checkIdentifiers); + } + + function checkSingleIdentifier(node: Node) { + const nodeLinks = getNodeLinks(node); + nodeLinks.calculatedFlags |= NodeCheckFlags.ConstructorReference | NodeCheckFlags.CapturedBlockScopedBinding | NodeCheckFlags.BlockScopedBindingInLoop; + if (isIdentifier(node) && isExpressionNode(node) && !(isPropertyAccessExpression(node.parent) && node.parent.name === node)) { + const s = getSymbolAtLocation(node, /*ignoreErrors*/ true); + if (s && s !== unknownSymbol) { + checkIdentifierCalculateNodeCheckFlags(node, s); + } + } + } + + function checkBlockScopeBindings(node: Node) { + const links = getNodeLinks(node); + if (links.calculatedFlags & flag) return "skip"; + links.calculatedFlags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding | NodeCheckFlags.BlockScopedBindingInLoop | NodeCheckFlags.CapturedBlockScopedBinding; + checkSingleBlockScopeBinding(node); + return undefined; + } + + function checkContainingBlockScopeBindingUses(node: Node) { + const scope = getEnclosingBlockScopeContainer(isDeclarationName(node) ? node.parent : node); + forEachNodeRecursively(scope, checkBlockScopeBindings); + } + + function checkSingleBlockScopeBinding(node: Node) { + checkSingleIdentifier(node); + if (isComputedPropertyName(node)) { + checkComputedPropertyName(node); + } + if (isPrivateIdentifier(node) && isClassElement(node.parent)) { + setNodeLinksForPrivateIdentifierScope(node.parent as PropertyDeclaration | PropertySignature | MethodDeclaration | MethodSignature | AccessorDeclaration); + } + } + } + + function getEnumMemberValue(node: EnumMember): EvaluatorResult { + computeEnumMemberValues(node.parent); + return getNodeLinks(node).enumMemberValue ?? evaluatorResult(/*value*/ undefined); + } + + function canHaveConstantValue(node: Node): node is EnumMember | AccessExpression { + switch (node.kind) { + case SyntaxKind.EnumMember: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + return true; + } + return false; + } + + function getConstantValue(node: EnumMember | AccessExpression): string | number | undefined { + if (node.kind === SyntaxKind.EnumMember) { + return getEnumMemberValue(node).value; + } + + if (!getNodeLinks(node).resolvedSymbol) { + void checkExpressionCached(node); // ensure cached resolved symbol is set + } + const symbol = getNodeLinks(node).resolvedSymbol || (isEntityNameExpression(node) ? resolveEntityName(node, SymbolFlags.Value, /*ignoreErrors*/ true) : undefined); + if (symbol && (symbol.flags & SymbolFlags.EnumMember)) { + // inline property\index accesses only for const enums + const member = symbol.valueDeclaration as EnumMember; + if (isEnumConst(member.parent)) { + return getEnumMemberValue(member).value; + } + } + + return undefined; + } + + function isFunctionType(type: Type): boolean { + return !!(type.flags & TypeFlags.Object) && getSignaturesOfType(type, SignatureKind.Call).length > 0; + } + + function getTypeReferenceSerializationKind(typeNameIn: EntityName, location?: Node): TypeReferenceSerializationKind { + // ensure both `typeName` and `location` are parse tree nodes. + const typeName = getParseTreeNode(typeNameIn, isEntityName); + if (!typeName) return TypeReferenceSerializationKind.Unknown; + + if (location) { + location = getParseTreeNode(location); + if (!location) return TypeReferenceSerializationKind.Unknown; + } + + // Resolve the symbol as a value to ensure the type can be reached at runtime during emit. + let isTypeOnly = false; + if (isQualifiedName(typeName)) { + const rootValueSymbol = resolveEntityName(getFirstIdentifier(typeName), SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location); + isTypeOnly = !!rootValueSymbol?.declarations?.every(isTypeOnlyImportOrExportDeclaration); + } + const valueSymbol = resolveEntityName(typeName, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location); + const resolvedValueSymbol = valueSymbol && valueSymbol.flags & SymbolFlags.Alias ? resolveAlias(valueSymbol) : valueSymbol; + isTypeOnly ||= !!(valueSymbol && getTypeOnlyAliasDeclaration(valueSymbol, SymbolFlags.Value)); + + // Resolve the symbol as a type so that we can provide a more useful hint for the type serializer. + const typeSymbol = resolveEntityName(typeName, SymbolFlags.Type, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location); + const resolvedTypeSymbol = typeSymbol && typeSymbol.flags & SymbolFlags.Alias ? resolveAlias(typeSymbol) : typeSymbol; + + // In case the value symbol can't be resolved (e.g. because of missing declarations), use type symbol for reachability check. + if (!valueSymbol) { + isTypeOnly ||= !!(typeSymbol && getTypeOnlyAliasDeclaration(typeSymbol, SymbolFlags.Type)); + } + + if (resolvedValueSymbol && resolvedValueSymbol === resolvedTypeSymbol) { + const globalPromiseSymbol = getGlobalPromiseConstructorSymbol(/*reportErrors*/ false); + if (globalPromiseSymbol && resolvedValueSymbol === globalPromiseSymbol) { + return TypeReferenceSerializationKind.Promise; + } + + const constructorType = getTypeOfSymbol(resolvedValueSymbol); + if (constructorType && isConstructorType(constructorType)) { + return isTypeOnly ? TypeReferenceSerializationKind.TypeWithCallSignature : TypeReferenceSerializationKind.TypeWithConstructSignatureAndValue; + } + } + + // We might not be able to resolve type symbol so use unknown type in that case (eg error case) + if (!resolvedTypeSymbol) { + return isTypeOnly ? TypeReferenceSerializationKind.ObjectType : TypeReferenceSerializationKind.Unknown; + } + const type = getDeclaredTypeOfSymbol(resolvedTypeSymbol); + if (isErrorType(type)) { + return isTypeOnly ? TypeReferenceSerializationKind.ObjectType : TypeReferenceSerializationKind.Unknown; + } + else if (type.flags & TypeFlags.AnyOrUnknown) { + return TypeReferenceSerializationKind.ObjectType; + } + else if (isTypeAssignableToKind(type, TypeFlags.Void | TypeFlags.Nullable | TypeFlags.Never)) { + return TypeReferenceSerializationKind.VoidNullableOrNeverType; + } + else if (isTypeAssignableToKind(type, TypeFlags.BooleanLike)) { + return TypeReferenceSerializationKind.BooleanType; + } + else if (isTypeAssignableToKind(type, TypeFlags.NumberLike)) { + return TypeReferenceSerializationKind.NumberLikeType; + } + else if (isTypeAssignableToKind(type, TypeFlags.BigIntLike)) { + return TypeReferenceSerializationKind.BigIntLikeType; + } + else if (isTypeAssignableToKind(type, TypeFlags.StringLike)) { + return TypeReferenceSerializationKind.StringLikeType; + } + else if (isTupleType(type)) { + return TypeReferenceSerializationKind.ArrayLikeType; + } + else if (isTypeAssignableToKind(type, TypeFlags.ESSymbolLike)) { + return TypeReferenceSerializationKind.ESSymbolType; + } + else if (isFunctionType(type)) { + return TypeReferenceSerializationKind.TypeWithCallSignature; + } + else if (isArrayType(type)) { + return TypeReferenceSerializationKind.ArrayLikeType; + } + else { + return TypeReferenceSerializationKind.ObjectType; + } + } + + function createTypeOfDeclaration(declarationIn: AccessorDeclaration | VariableLikeDeclaration | PropertyAccessExpression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) { + const declaration = getParseTreeNode(declarationIn, isVariableLikeOrAccessor); + if (!declaration) { + return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode; + } + // Get type of the symbol if this is the valid symbol otherwise get type at location + const symbol = getSymbolOfDeclaration(declaration); + const type = symbol && !(symbol.flags & (SymbolFlags.TypeLiteral | SymbolFlags.Signature)) + ? getWidenedLiteralType(getTypeOfSymbol(symbol)) + : errorType; + + return nodeBuilder.serializeTypeForDeclaration(declaration, type, symbol, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker); + } + + type DeclarationWithPotentialInnerNodeReuse = + | SignatureDeclaration + | JSDocSignature + | AccessorDeclaration + | VariableLikeDeclaration + | PropertyAccessExpression + | ExportAssignment; + + function isDeclarationWithPossibleInnerTypeNodeReuse(declaration: Declaration): declaration is DeclarationWithPotentialInnerNodeReuse { + return isFunctionLike(declaration) || isExportAssignment(declaration) || isVariableLike(declaration); + } + + function getAllAccessorDeclarationsForDeclaration(accessor: AccessorDeclaration): AllAccessorDeclarations { + accessor = getParseTreeNode(accessor, isGetOrSetAccessorDeclaration)!; // TODO: GH#18217 + const otherKind = accessor.kind === SyntaxKind.SetAccessor ? SyntaxKind.GetAccessor : SyntaxKind.SetAccessor; + const otherAccessor = getDeclarationOfKind(getSymbolOfDeclaration(accessor), otherKind); + const firstAccessor = otherAccessor && (otherAccessor.pos < accessor.pos) ? otherAccessor : accessor; + const secondAccessor = otherAccessor && (otherAccessor.pos < accessor.pos) ? accessor : otherAccessor; + const setAccessor = accessor.kind === SyntaxKind.SetAccessor ? accessor : otherAccessor as SetAccessorDeclaration; + const getAccessor = accessor.kind === SyntaxKind.GetAccessor ? accessor : otherAccessor as GetAccessorDeclaration; + return { + firstAccessor, + secondAccessor, + setAccessor, + getAccessor, + }; + } + + function getPossibleTypeNodeReuseExpression(declaration: DeclarationWithPotentialInnerNodeReuse) { + return isFunctionLike(declaration) && !isSetAccessor(declaration) + ? getSingleReturnExpression(declaration) + : isExportAssignment(declaration) + ? declaration.expression + : !!(declaration as HasInitializer).initializer + ? (declaration as HasInitializer & typeof declaration).initializer + : isParameter(declaration) && isSetAccessor(declaration.parent) + ? getSingleReturnExpression(getAllAccessorDeclarationsForDeclaration(declaration.parent).getAccessor) + : undefined; + } + + function getSingleReturnExpression(declaration: SignatureDeclaration | undefined): Expression | undefined { + let candidateExpr: Expression | undefined; + if (declaration && !nodeIsMissing((declaration as FunctionLikeDeclaration).body)) { + if (getFunctionFlags(declaration) & FunctionFlags.AsyncGenerator) return undefined; + const body = (declaration as FunctionLikeDeclaration).body; + if (body && isBlock(body)) { + forEachReturnStatement(body, s => { + if (!candidateExpr) { + candidateExpr = s.expression; + } + else { + candidateExpr = undefined; + return true; + } + }); + } + else { + candidateExpr = body; + } + } + return candidateExpr; + } + + function createReturnTypeOfSignatureDeclaration(signatureDeclarationIn: SignatureDeclaration, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) { + const signatureDeclaration = getParseTreeNode(signatureDeclarationIn, isFunctionLike); + if (!signatureDeclaration) { + return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode; + } + return nodeBuilder.serializeReturnTypeForSignature(getSignatureFromDeclaration(signatureDeclaration), enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker); + } + + function createTypeOfExpression(exprIn: Expression, enclosingDeclaration: Node, flags: NodeBuilderFlags, tracker: SymbolTracker) { + const expr = getParseTreeNode(exprIn, isExpression); + if (!expr) { + return factory.createToken(SyntaxKind.AnyKeyword) as KeywordTypeNode; + } + const type = getWidenedType(getRegularTypeOfExpression(expr)); + return nodeBuilder.expressionOrTypeToTypeNode(expr, type, /*addUndefined*/ undefined, enclosingDeclaration, flags | NodeBuilderFlags.MultilineObjectLiterals, tracker); + } + + function hasGlobalName(name: string): boolean { + return globals.has(escapeLeadingUnderscores(name)); + } + + function getReferencedValueSymbol(reference: Identifier, startInDeclarationContainer?: boolean): Symbol | undefined { + const resolvedSymbol = getNodeLinks(reference).resolvedSymbol; + if (resolvedSymbol) { + return resolvedSymbol; + } + + let location: Node = reference; + if (startInDeclarationContainer) { + // When resolving the name of a declaration as a value, we need to start resolution + // at a point outside of the declaration. + const parent = reference.parent; + if (isDeclaration(parent) && reference === parent.name) { + location = getDeclarationContainer(parent); + } + } + + return resolveName(location, reference.escapedText, SymbolFlags.Value | SymbolFlags.ExportValue | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + } + + /** + * Get either a value-meaning symbol or an alias symbol. + * Unlike `getReferencedValueSymbol`, if the cached resolved symbol is the unknown symbol, + * we call `resolveName` to find a symbol. + * This is because when caching the resolved symbol, we only consider value symbols, but here + * we want to also get an alias symbol if one exists. + */ + function getReferencedValueOrAliasSymbol(reference: Identifier): Symbol | undefined { + const resolvedSymbol = getNodeLinks(reference).resolvedSymbol; + if (resolvedSymbol && resolvedSymbol !== unknownSymbol) { + return resolvedSymbol; + } + + return resolveName( + reference, + reference.escapedText, + SymbolFlags.Value | SymbolFlags.ExportValue | SymbolFlags.Alias, + /*nameNotFoundMessage*/ undefined, + /*isUse*/ true, + /*excludeGlobals*/ undefined, + ); + } + + function getReferencedValueDeclaration(referenceIn: Identifier): Declaration | undefined { + if (!isGeneratedIdentifier(referenceIn)) { + const reference = getParseTreeNode(referenceIn, isIdentifier); + if (reference) { + const symbol = getReferencedValueSymbol(reference); + if (symbol) { + return getExportSymbolOfValueSymbolIfExported(symbol).valueDeclaration; + } + } + } + + return undefined; + } + + function getReferencedValueDeclarations(referenceIn: Identifier): Declaration[] | undefined { + if (!isGeneratedIdentifier(referenceIn)) { + const reference = getParseTreeNode(referenceIn, isIdentifier); + if (reference) { + const symbol = getReferencedValueSymbol(reference); + if (symbol) { + return filter(getExportSymbolOfValueSymbolIfExported(symbol).declarations, declaration => { + switch (declaration.kind) { + case SyntaxKind.VariableDeclaration: + case SyntaxKind.Parameter: + case SyntaxKind.BindingElement: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertyAssignment: + case SyntaxKind.ShorthandPropertyAssignment: + case SyntaxKind.EnumMember: + case SyntaxKind.ObjectLiteralExpression: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.ModuleDeclaration: + return true; + } + return false; + }); + } + } + } + + return undefined; + } + + function isLiteralConstDeclaration(node: VariableDeclaration | PropertyDeclaration | PropertySignature | ParameterDeclaration): boolean { + if (isDeclarationReadonly(node) || isVariableDeclaration(node) && isVarConstLike(node)) { + return isFreshLiteralType(getTypeOfSymbol(getSymbolOfDeclaration(node))); + } + return false; + } + + function literalTypeToNode(type: FreshableType, enclosing: Node, tracker: SymbolTracker): Expression { + const enumResult = type.flags & TypeFlags.EnumLike ? nodeBuilder.symbolToExpression(type.symbol, SymbolFlags.Value, enclosing, /*flags*/ undefined, tracker) + : type === trueType ? factory.createTrue() : type === falseType && factory.createFalse(); + if (enumResult) return enumResult; + const literalValue = (type as LiteralType).value; + return typeof literalValue === "object" ? factory.createBigIntLiteral(literalValue) : + typeof literalValue === "string" ? factory.createStringLiteral(literalValue) : + literalValue < 0 ? factory.createPrefixUnaryExpression(SyntaxKind.MinusToken, factory.createNumericLiteral(-literalValue)) : + factory.createNumericLiteral(literalValue); + } + + function createLiteralConstValue(node: VariableDeclaration | PropertyDeclaration | PropertySignature | ParameterDeclaration, tracker: SymbolTracker) { + const type = getTypeOfSymbol(getSymbolOfDeclaration(node)); + return literalTypeToNode(type as FreshableType, node, tracker); + } + + function getJsxFactoryEntity(location: Node): EntityName | undefined { + return location ? (getJsxNamespace(location), (getSourceFileOfNode(location).localJsxFactory || _jsxFactoryEntity)) : _jsxFactoryEntity; + } + + function getJsxFragmentFactoryEntity(location: Node): EntityName | undefined { + if (location) { + const file = getSourceFileOfNode(location); + if (file) { + if (file.localJsxFragmentFactory) { + return file.localJsxFragmentFactory; + } + const jsxFragPragmas = file.pragmas.get("jsxfrag"); + const jsxFragPragma = isArray(jsxFragPragmas) ? jsxFragPragmas[0] : jsxFragPragmas; + if (jsxFragPragma) { + file.localJsxFragmentFactory = parseIsolatedEntityName(jsxFragPragma.arguments.factory, languageVersion); + return file.localJsxFragmentFactory; + } + } + } + + if (compilerOptions.jsxFragmentFactory) { + return parseIsolatedEntityName(compilerOptions.jsxFragmentFactory, languageVersion); + } + } + + function getNonlocalEffectiveTypeAnnotationNode(node: Node) { + const direct = getEffectiveTypeAnnotationNode(node); + if (direct) { + return direct; + } + if (node.kind === SyntaxKind.Parameter && node.parent.kind === SyntaxKind.SetAccessor) { + const other = getAllAccessorDeclarationsForDeclaration(node.parent as SetAccessorDeclaration).getAccessor; + if (other) { + return getEffectiveReturnTypeNode(other); + } + } + return undefined; + } + + function getNonlocalEffectiveReturnTypeAnnotationNode(node: SignatureDeclaration | JSDocSignature) { + const direct = getEffectiveReturnTypeNode(node); + if (direct) { + return direct; + } + if (node.kind === SyntaxKind.GetAccessor) { + const other = getAllAccessorDeclarationsForDeclaration(node).setAccessor; + if (other) { + const param = getSetAccessorValueParameter(other); + if (param) { + return getEffectiveTypeAnnotationNode(param); + } + } + } + return undefined; + } + + function createResolver(): EmitResolver { + return { + getReferencedExportContainer, + getReferencedImportDeclaration, + getReferencedDeclarationWithCollidingName, + isDeclarationWithCollidingName, + isValueAliasDeclaration: nodeIn => { + const node = getParseTreeNode(nodeIn); + // Synthesized nodes are always treated like values. + return node && canCollectSymbolAliasAccessabilityData ? isValueAliasDeclaration(node) : true; + }, + hasGlobalName, + isReferencedAliasDeclaration: (nodeIn, checkChildren?) => { + const node = getParseTreeNode(nodeIn); + // Synthesized nodes are always treated as referenced. + return node && canCollectSymbolAliasAccessabilityData ? isReferencedAliasDeclaration(node, checkChildren) : true; + }, + hasNodeCheckFlag: (nodeIn, flag) => { + const node = getParseTreeNode(nodeIn); + if (!node) return false; + return hasNodeCheckFlag(node, flag); + }, + isTopLevelValueImportEqualsWithEntityName, + isDeclarationVisible, + isImplementationOfOverload, + requiresAddingImplicitUndefined, + isExpandoFunctionDeclaration, + getPropertiesOfContainerFunction, + createTypeOfDeclaration, + createReturnTypeOfSignatureDeclaration, + createTypeOfExpression, + createLiteralConstValue, + isSymbolAccessible, + isEntityNameVisible, + getConstantValue: nodeIn => { + const node = getParseTreeNode(nodeIn, canHaveConstantValue); + return node ? getConstantValue(node) : undefined; + }, + getEnumMemberValue: nodeIn => { + const node = getParseTreeNode(nodeIn, isEnumMember); + return node ? getEnumMemberValue(node) : undefined; + }, + collectLinkedAliases, + markLinkedReferences: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node && markLinkedReferences(node, ReferenceHint.Unspecified); + }, + getReferencedValueDeclaration, + getReferencedValueDeclarations, + getTypeReferenceSerializationKind, + isOptionalParameter, + isArgumentsLocalBinding, + getExternalModuleFileFromDeclaration: nodeIn => { + const node = getParseTreeNode(nodeIn, hasPossibleExternalModuleReference); + return node && getExternalModuleFileFromDeclaration(node); + }, + isLiteralConstDeclaration, + isLateBound: (nodeIn: Declaration): nodeIn is LateBoundDeclaration => { + const node = getParseTreeNode(nodeIn, isDeclaration); + const symbol = node && getSymbolOfDeclaration(node); + return !!(symbol && getCheckFlags(symbol) & CheckFlags.Late); + }, + getJsxFactoryEntity, + getJsxFragmentFactoryEntity, + isBindingCapturedByNode: (node, decl) => { + const parseNode = getParseTreeNode(node); + const parseDecl = getParseTreeNode(decl); + return !!parseNode && !!parseDecl && (isVariableDeclaration(parseDecl) || isBindingElement(parseDecl)) && isBindingCapturedByNode(parseNode, parseDecl); + }, + getDeclarationStatementsForSourceFile: (node, flags, tracker) => { + const n = getParseTreeNode(node) as SourceFile; + Debug.assert(n && n.kind === SyntaxKind.SourceFile, "Non-sourcefile node passed into getDeclarationsForSourceFile"); + const sym = getSymbolOfDeclaration(node); + if (!sym) { + return !node.locals ? [] : nodeBuilder.symbolTableToDeclarationStatements(node.locals, node, flags, tracker); + } + resolveExternalModuleSymbol(sym); // ensures cjs export assignment is setup + return !sym.exports ? [] : nodeBuilder.symbolTableToDeclarationStatements(sym.exports, node, flags, tracker); + }, + isImportRequiredByAugmentation, + isDefinitelyReferenceToGlobalSymbolObject, + }; + + function isImportRequiredByAugmentation(node: ImportDeclaration) { + const file = getSourceFileOfNode(node); + if (!file.symbol) return false; + const importTarget = getExternalModuleFileFromDeclaration(node); + if (!importTarget) return false; + if (importTarget === file) return false; + const exports = getExportsOfModule(file.symbol); + for (const s of arrayFrom(exports.values())) { + if (s.mergeId) { + const merged = getMergedSymbol(s); + if (merged.declarations) { + for (const d of merged.declarations) { + const declFile = getSourceFileOfNode(d); + if (declFile === importTarget) { + return true; + } + } + } + } + } + return false; + } + } + + function getExternalModuleFileFromDeclaration(declaration: AnyImportOrReExport | ModuleDeclaration | ImportTypeNode | ImportCall): SourceFile | undefined { + const specifier = declaration.kind === SyntaxKind.ModuleDeclaration ? tryCast(declaration.name, isStringLiteral) : getExternalModuleName(declaration); + const moduleSymbol = resolveExternalModuleNameWorker(specifier!, specifier!, /*moduleNotFoundError*/ undefined); // TODO: GH#18217 + if (!moduleSymbol) { + return undefined; + } + return getDeclarationOfKind(moduleSymbol, SyntaxKind.SourceFile); + } + + function initializeTypeChecker() { + // Bind all source files and propagate errors + for (const file of host.getSourceFiles()) { + bindSourceFile(file, compilerOptions); + } + + amalgamatedDuplicates = new Map(); + + // Initialize global symbol table + let augmentations: (readonly (StringLiteral | Identifier)[])[] | undefined; + for (const file of host.getSourceFiles()) { + if (file.redirectInfo) { + continue; + } + if (!isExternalOrCommonJsModule(file)) { + // It is an error for a non-external-module (i.e. script) to declare its own `globalThis`. + const fileGlobalThisSymbol = file.locals!.get("globalThis" as __String); + if (fileGlobalThisSymbol?.declarations) { + for (const declaration of fileGlobalThisSymbol.declarations) { + diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Declaration_name_conflicts_with_built_in_global_identifier_0, "globalThis")); + } + } + mergeSymbolTable(globals, file.locals!); + } + if (file.jsGlobalAugmentations) { + mergeSymbolTable(globals, file.jsGlobalAugmentations); + } + if (file.patternAmbientModules && file.patternAmbientModules.length) { + patternAmbientModules = concatenate(patternAmbientModules, file.patternAmbientModules); + } + if (file.moduleAugmentations.length) { + (augmentations || (augmentations = [])).push(file.moduleAugmentations); + } + if (file.symbol && file.symbol.globalExports) { + // Merge in UMD exports with first-in-wins semantics (see #9771) + const source = file.symbol.globalExports; + source.forEach((sourceSymbol, id) => { + if (!globals.has(id)) { + globals.set(id, sourceSymbol); + } + }); + } + } + + // We do global augmentations separately from module augmentations (and before creating global types) because they + // 1. Affect global types. We won't have the correct global types until global augmentations are merged. Also, + // 2. Module augmentation instantiation requires creating the type of a module, which, in turn, can require + // checking for an export or property on the module (if export=) which, in turn, can fall back to the + // apparent type of the module - either globalObjectType or globalFunctionType - which wouldn't exist if we + // did module augmentations prior to finalizing the global types. + if (augmentations) { + // merge _global_ module augmentations. + // this needs to be done after global symbol table is initialized to make sure that all ambient modules are indexed + for (const list of augmentations) { + for (const augmentation of list) { + if (!isGlobalScopeAugmentation(augmentation.parent as ModuleDeclaration)) continue; + mergeModuleAugmentation(augmentation); + } + } + } + + addUndefinedToGlobalsOrErrorOnRedeclaration(); + + getSymbolLinks(undefinedSymbol).type = undefinedWideningType; + getSymbolLinks(argumentsSymbol).type = getGlobalType("IArguments" as __String, /*arity*/ 0, /*reportErrors*/ true); + getSymbolLinks(unknownSymbol).type = errorType; + getSymbolLinks(globalThisSymbol).type = createObjectType(ObjectFlags.Anonymous, globalThisSymbol); + + // Initialize special types + globalArrayType = getGlobalType("Array" as __String, /*arity*/ 1, /*reportErrors*/ true); + globalObjectType = getGlobalType("Object" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalFunctionType = getGlobalType("Function" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalCallableFunctionType = strictBindCallApply && getGlobalType("CallableFunction" as __String, /*arity*/ 0, /*reportErrors*/ true) || globalFunctionType; + globalNewableFunctionType = strictBindCallApply && getGlobalType("NewableFunction" as __String, /*arity*/ 0, /*reportErrors*/ true) || globalFunctionType; + globalStringType = getGlobalType("String" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalNumberType = getGlobalType("Number" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalBooleanType = getGlobalType("Boolean" as __String, /*arity*/ 0, /*reportErrors*/ true); + globalRegExpType = getGlobalType("RegExp" as __String, /*arity*/ 0, /*reportErrors*/ true); + anyArrayType = createArrayType(anyType); + + autoArrayType = createArrayType(autoType); + if (autoArrayType === emptyObjectType) { + // autoArrayType is used as a marker, so even if global Array type is not defined, it needs to be a unique type + autoArrayType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + } + + globalReadonlyArrayType = getGlobalTypeOrUndefined("ReadonlyArray" as __String, /*arity*/ 1) as GenericType || globalArrayType; + anyReadonlyArrayType = globalReadonlyArrayType ? createTypeFromGenericGlobalType(globalReadonlyArrayType, [anyType]) : anyArrayType; + globalThisType = getGlobalTypeOrUndefined("ThisType" as __String, /*arity*/ 1) as GenericType; + + if (augmentations) { + // merge _nonglobal_ module augmentations. + // this needs to be done after global symbol table is initialized to make sure that all ambient modules are indexed + for (const list of augmentations) { + for (const augmentation of list) { + if (isGlobalScopeAugmentation(augmentation.parent as ModuleDeclaration)) continue; + mergeModuleAugmentation(augmentation); + } + } + } + + amalgamatedDuplicates.forEach(({ firstFile, secondFile, conflictingSymbols }) => { + // If not many things conflict, issue individual errors + if (conflictingSymbols.size < 8) { + conflictingSymbols.forEach(({ isBlockScoped, firstFileLocations, secondFileLocations }, symbolName) => { + const message = isBlockScoped ? Diagnostics.Cannot_redeclare_block_scoped_variable_0 : Diagnostics.Duplicate_identifier_0; + for (const node of firstFileLocations) { + addDuplicateDeclarationError(node, message, symbolName, secondFileLocations); + } + for (const node of secondFileLocations) { + addDuplicateDeclarationError(node, message, symbolName, firstFileLocations); + } + }); + } + else { + // Otherwise issue top-level error since the files appear very identical in terms of what they contain + const list = arrayFrom(conflictingSymbols.keys()).join(", "); + diagnostics.add(addRelatedInfo( + createDiagnosticForNode(firstFile, Diagnostics.Definitions_of_the_following_identifiers_conflict_with_those_in_another_file_Colon_0, list), + createDiagnosticForNode(secondFile, Diagnostics.Conflicts_are_in_this_file), + )); + diagnostics.add(addRelatedInfo( + createDiagnosticForNode(secondFile, Diagnostics.Definitions_of_the_following_identifiers_conflict_with_those_in_another_file_Colon_0, list), + createDiagnosticForNode(firstFile, Diagnostics.Conflicts_are_in_this_file), + )); + } + }); + amalgamatedDuplicates = undefined; + } + + function checkExternalEmitHelpers(location: Node, helpers: ExternalEmitHelpers) { + if (compilerOptions.importHelpers) { + const sourceFile = getSourceFileOfNode(location); + if (isEffectiveExternalModule(sourceFile, compilerOptions) && !(location.flags & NodeFlags.Ambient)) { + const helpersModule = resolveHelpersModule(sourceFile, location); + if (helpersModule !== unknownSymbol) { + const links = getSymbolLinks(helpersModule); + links.requestedExternalEmitHelpers ??= 0 as ExternalEmitHelpers; + if ((links.requestedExternalEmitHelpers & helpers) !== helpers) { + const uncheckedHelpers = helpers & ~links.requestedExternalEmitHelpers; + for (let helper = ExternalEmitHelpers.FirstEmitHelper; helper <= ExternalEmitHelpers.LastEmitHelper; helper <<= 1) { + if (uncheckedHelpers & helper) { + for (const name of getHelperNames(helper)) { + const symbol = resolveSymbol(getSymbol(getExportsOfModule(helpersModule), escapeLeadingUnderscores(name), SymbolFlags.Value)); + if (!symbol) { + error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_which_does_not_exist_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name); + } + else if (helper & ExternalEmitHelpers.ClassPrivateFieldGet) { + if (!some(getSignaturesOfSymbol(symbol), signature => getParameterCount(signature) > 3)) { + error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_with_2_parameters_which_is_not_compatible_with_the_one_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name, 4); + } + } + else if (helper & ExternalEmitHelpers.ClassPrivateFieldSet) { + if (!some(getSignaturesOfSymbol(symbol), signature => getParameterCount(signature) > 4)) { + error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_with_2_parameters_which_is_not_compatible_with_the_one_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name, 5); + } + } + else if (helper & ExternalEmitHelpers.SpreadArray) { + if (!some(getSignaturesOfSymbol(symbol), signature => getParameterCount(signature) > 2)) { + error(location, Diagnostics.This_syntax_requires_an_imported_helper_named_1_with_2_parameters_which_is_not_compatible_with_the_one_in_0_Consider_upgrading_your_version_of_0, externalHelpersModuleNameText, name, 3); + } + } + } + } + } + } + links.requestedExternalEmitHelpers |= helpers; + } + } + } + } + + function getHelperNames(helper: ExternalEmitHelpers) { + switch (helper) { + case ExternalEmitHelpers.Extends: + return ["__extends"]; + case ExternalEmitHelpers.Assign: + return ["__assign"]; + case ExternalEmitHelpers.Rest: + return ["__rest"]; + case ExternalEmitHelpers.Decorate: + return legacyDecorators ? ["__decorate"] : ["__esDecorate", "__runInitializers"]; + case ExternalEmitHelpers.Metadata: + return ["__metadata"]; + case ExternalEmitHelpers.Param: + return ["__param"]; + case ExternalEmitHelpers.Awaiter: + return ["__awaiter"]; + case ExternalEmitHelpers.Generator: + return ["__generator"]; + case ExternalEmitHelpers.Values: + return ["__values"]; + case ExternalEmitHelpers.Read: + return ["__read"]; + case ExternalEmitHelpers.SpreadArray: + return ["__spreadArray"]; + case ExternalEmitHelpers.Await: + return ["__await"]; + case ExternalEmitHelpers.AsyncGenerator: + return ["__asyncGenerator"]; + case ExternalEmitHelpers.AsyncDelegator: + return ["__asyncDelegator"]; + case ExternalEmitHelpers.AsyncValues: + return ["__asyncValues"]; + case ExternalEmitHelpers.ExportStar: + return ["__exportStar"]; + case ExternalEmitHelpers.ImportStar: + return ["__importStar"]; + case ExternalEmitHelpers.ImportDefault: + return ["__importDefault"]; + case ExternalEmitHelpers.MakeTemplateObject: + return ["__makeTemplateObject"]; + case ExternalEmitHelpers.ClassPrivateFieldGet: + return ["__classPrivateFieldGet"]; + case ExternalEmitHelpers.ClassPrivateFieldSet: + return ["__classPrivateFieldSet"]; + case ExternalEmitHelpers.ClassPrivateFieldIn: + return ["__classPrivateFieldIn"]; + case ExternalEmitHelpers.SetFunctionName: + return ["__setFunctionName"]; + case ExternalEmitHelpers.PropKey: + return ["__propKey"]; + case ExternalEmitHelpers.AddDisposableResourceAndDisposeResources: + return ["__addDisposableResource", "__disposeResources"]; + default: + return Debug.fail("Unrecognized helper"); + } + } + + function resolveHelpersModule(file: SourceFile, errorNode: Node) { + const links = getNodeLinks(file); + if (!links.externalHelpersModule) { + links.externalHelpersModule = resolveExternalModule(getImportHelpersImportSpecifier(file), externalHelpersModuleNameText, Diagnostics.This_syntax_requires_an_imported_helper_but_module_0_cannot_be_found, errorNode) || unknownSymbol; + } + return links.externalHelpersModule; + } + + // GRAMMAR CHECKING + + function checkGrammarModifiers(node: HasModifiers | HasDecorators | HasIllegalModifiers | HasIllegalDecorators): boolean { + const quickResult = reportObviousDecoratorErrors(node) || reportObviousModifierErrors(node); + if (quickResult !== undefined) { + return quickResult; + } + + if (isParameter(node) && parameterIsThisKeyword(node)) { + return grammarErrorOnFirstToken(node, Diagnostics.Neither_decorators_nor_modifiers_may_be_applied_to_this_parameters); + } + + const blockScopeKind = isVariableStatement(node) ? node.declarationList.flags & NodeFlags.BlockScoped : NodeFlags.None; + let lastStatic: Node | undefined, lastDeclare: Node | undefined, lastAsync: Node | undefined, lastOverride: Node | undefined, firstDecorator: Decorator | undefined; + let flags = ModifierFlags.None; + let sawExportBeforeDecorators = false; + // We parse decorators and modifiers in four contiguous chunks: + // [...leadingDecorators, ...leadingModifiers, ...trailingDecorators, ...trailingModifiers]. It is an error to + // have both leading and trailing decorators. + let hasLeadingDecorators = false; + for (const modifier of (node as HasModifiers).modifiers!) { + if (isDecorator(modifier)) { + if (!nodeCanBeDecorated(legacyDecorators, node, node.parent, node.parent.parent)) { + if (node.kind === SyntaxKind.MethodDeclaration && !nodeIsPresent(node.body)) { + return grammarErrorOnFirstToken(node, Diagnostics.A_decorator_can_only_decorate_a_method_implementation_not_an_overload); + } + else { + return grammarErrorOnFirstToken(node, Diagnostics.Decorators_are_not_valid_here); + } + } + else if (legacyDecorators && (node.kind === SyntaxKind.GetAccessor || node.kind === SyntaxKind.SetAccessor)) { + const accessors = getAllAccessorDeclarationsForDeclaration(node as AccessorDeclaration); + if (hasDecorators(accessors.firstAccessor) && node === accessors.secondAccessor) { + return grammarErrorOnFirstToken(node, Diagnostics.Decorators_cannot_be_applied_to_multiple_get_Slashset_accessors_of_the_same_name); + } + } + + // if we've seen any modifiers aside from `export`, `default`, or another decorator, then this is an invalid position + if (flags & ~(ModifierFlags.ExportDefault | ModifierFlags.Decorator)) { + return grammarErrorOnNode(modifier, Diagnostics.Decorators_are_not_valid_here); + } + + // if we've already seen leading decorators and leading modifiers, then trailing decorators are an invalid position + if (hasLeadingDecorators && flags & ModifierFlags.Modifier) { + Debug.assertIsDefined(firstDecorator); + const sourceFile = getSourceFileOfNode(modifier); + if (!hasParseDiagnostics(sourceFile)) { + addRelatedInfo( + error(modifier, Diagnostics.Decorators_may_not_appear_after_export_or_export_default_if_they_also_appear_before_export), + createDiagnosticForNode(firstDecorator, Diagnostics.Decorator_used_before_export_here), + ); + return true; + } + return false; + } + + flags |= ModifierFlags.Decorator; + + // if we have not yet seen a modifier, then these are leading decorators + if (!(flags & ModifierFlags.Modifier)) { + hasLeadingDecorators = true; + } + else if (flags & ModifierFlags.Export) { + sawExportBeforeDecorators = true; + } + + firstDecorator ??= modifier; + } + else { + if (modifier.kind !== SyntaxKind.ReadonlyKeyword) { + if (node.kind === SyntaxKind.PropertySignature || node.kind === SyntaxKind.MethodSignature) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_type_member, tokenToString(modifier.kind)); + } + if (node.kind === SyntaxKind.IndexSignature && (modifier.kind !== SyntaxKind.StaticKeyword || !isClassLike(node.parent))) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_an_index_signature, tokenToString(modifier.kind)); + } + } + if (modifier.kind !== SyntaxKind.InKeyword && modifier.kind !== SyntaxKind.OutKeyword && modifier.kind !== SyntaxKind.ConstKeyword) { + if (node.kind === SyntaxKind.TypeParameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_type_parameter, tokenToString(modifier.kind)); + } + } + switch (modifier.kind) { + case SyntaxKind.ConstKeyword: { + if (node.kind !== SyntaxKind.EnumDeclaration && node.kind !== SyntaxKind.TypeParameter) { + return grammarErrorOnNode(node, Diagnostics.A_class_member_cannot_have_the_0_keyword, tokenToString(SyntaxKind.ConstKeyword)); + } + const parent = (isJSDocTemplateTag(node.parent) && getEffectiveJSDocHost(node.parent)) || node.parent; + if ( + node.kind === SyntaxKind.TypeParameter && !(isFunctionLikeDeclaration(parent) || isClassLike(parent) || isFunctionTypeNode(parent) || + isConstructorTypeNode(parent) || isCallSignatureDeclaration(parent) || isConstructSignatureDeclaration(parent) || isMethodSignature(parent)) + ) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_can_only_appear_on_a_type_parameter_of_a_function_method_or_class, tokenToString(modifier.kind)); + } + break; + } + case SyntaxKind.OverrideKeyword: + // If node.kind === SyntaxKind.Parameter, checkParameter reports an error if it's not a parameter property. + if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "override"); + } + else if (flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "override", "declare"); + } + else if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "override", "readonly"); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "override", "accessor"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "override", "async"); + } + flags |= ModifierFlags.Override; + lastOverride = modifier; + break; + + case SyntaxKind.PublicKeyword: + case SyntaxKind.ProtectedKeyword: + case SyntaxKind.PrivateKeyword: + const text = visibilityToString(modifierToFlag(modifier.kind)); + + if (flags & ModifierFlags.AccessibilityModifier) { + return grammarErrorOnNode(modifier, Diagnostics.Accessibility_modifier_already_seen); + } + else if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "override"); + } + else if (flags & ModifierFlags.Static) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "static"); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "accessor"); + } + else if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "readonly"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "async"); + } + else if (node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_module_or_namespace_element, text); + } + else if (flags & ModifierFlags.Abstract) { + if (modifier.kind === SyntaxKind.PrivateKeyword) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, text, "abstract"); + } + else { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, text, "abstract"); + } + } + else if (isPrivateIdentifierClassElementDeclaration(node)) { + return grammarErrorOnNode(modifier, Diagnostics.An_accessibility_modifier_cannot_be_used_with_a_private_identifier); + } + flags |= modifierToFlag(modifier.kind); + break; + + case SyntaxKind.StaticKeyword: + if (flags & ModifierFlags.Static) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "static"); + } + else if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "readonly"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "async"); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "accessor"); + } + else if (node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_module_or_namespace_element, "static"); + } + else if (node.kind === SyntaxKind.Parameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "static"); + } + else if (flags & ModifierFlags.Abstract) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "static", "abstract"); + } + else if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "static", "override"); + } + flags |= ModifierFlags.Static; + lastStatic = modifier; + break; + + case SyntaxKind.AccessorKeyword: + if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "accessor"); + } + else if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "accessor", "readonly"); + } + else if (flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "accessor", "declare"); + } + else if (node.kind !== SyntaxKind.PropertyDeclaration) { + return grammarErrorOnNode(modifier, Diagnostics.accessor_modifier_can_only_appear_on_a_property_declaration); + } + + flags |= ModifierFlags.Accessor; + break; + + case SyntaxKind.ReadonlyKeyword: + if (flags & ModifierFlags.Readonly) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "readonly"); + } + else if (node.kind !== SyntaxKind.PropertyDeclaration && node.kind !== SyntaxKind.PropertySignature && node.kind !== SyntaxKind.IndexSignature && node.kind !== SyntaxKind.Parameter) { + // If node.kind === SyntaxKind.Parameter, checkParameter reports an error if it's not a parameter property. + return grammarErrorOnNode(modifier, Diagnostics.readonly_modifier_can_only_appear_on_a_property_declaration_or_index_signature); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "readonly", "accessor"); + } + flags |= ModifierFlags.Readonly; + break; + + case SyntaxKind.ExportKeyword: + if ( + compilerOptions.verbatimModuleSyntax && + !(node.flags & NodeFlags.Ambient) && + node.kind !== SyntaxKind.TypeAliasDeclaration && + node.kind !== SyntaxKind.InterfaceDeclaration && + // ModuleDeclaration needs to be checked that it is uninstantiated later + node.kind !== SyntaxKind.ModuleDeclaration && + node.parent.kind === SyntaxKind.SourceFile && + (moduleKind === ModuleKind.CommonJS || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) + ) { + return grammarErrorOnNode(modifier, Diagnostics.A_top_level_export_modifier_cannot_be_used_on_value_declarations_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + if (flags & ModifierFlags.Export) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "export"); + } + else if (flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "declare"); + } + else if (flags & ModifierFlags.Abstract) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "abstract"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "async"); + } + else if (isClassLike(node.parent)) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_class_elements_of_this_kind, "export"); + } + else if (node.kind === SyntaxKind.Parameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "export"); + } + else if (blockScopeKind === NodeFlags.Using) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_using_declaration, "export"); + } + else if (blockScopeKind === NodeFlags.AwaitUsing) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_an_await_using_declaration, "export"); + } + flags |= ModifierFlags.Export; + break; + case SyntaxKind.DefaultKeyword: + const container = node.parent.kind === SyntaxKind.SourceFile ? node.parent : node.parent.parent; + if (container.kind === SyntaxKind.ModuleDeclaration && !isAmbientModule(container)) { + return grammarErrorOnNode(modifier, Diagnostics.A_default_export_can_only_be_used_in_an_ECMAScript_style_module); + } + else if (blockScopeKind === NodeFlags.Using) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_using_declaration, "default"); + } + else if (blockScopeKind === NodeFlags.AwaitUsing) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_an_await_using_declaration, "default"); + } + else if (!(flags & ModifierFlags.Export)) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "export", "default"); + } + else if (sawExportBeforeDecorators) { + return grammarErrorOnNode(firstDecorator!, Diagnostics.Decorators_are_not_valid_here); + } + + flags |= ModifierFlags.Default; + break; + case SyntaxKind.DeclareKeyword: + if (flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "declare"); + } + else if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_in_an_ambient_context, "async"); + } + else if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_in_an_ambient_context, "override"); + } + else if (isClassLike(node.parent) && !isPropertyDeclaration(node)) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_class_elements_of_this_kind, "declare"); + } + else if (node.kind === SyntaxKind.Parameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "declare"); + } + else if (blockScopeKind === NodeFlags.Using) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_using_declaration, "declare"); + } + else if (blockScopeKind === NodeFlags.AwaitUsing) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_an_await_using_declaration, "declare"); + } + else if ((node.parent.flags & NodeFlags.Ambient) && node.parent.kind === SyntaxKind.ModuleBlock) { + return grammarErrorOnNode(modifier, Diagnostics.A_declare_modifier_cannot_be_used_in_an_already_ambient_context); + } + else if (isPrivateIdentifierClassElementDeclaration(node)) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_a_private_identifier, "declare"); + } + else if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "declare", "accessor"); + } + flags |= ModifierFlags.Ambient; + lastDeclare = modifier; + break; + + case SyntaxKind.AbstractKeyword: + if (flags & ModifierFlags.Abstract) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "abstract"); + } + if ( + node.kind !== SyntaxKind.ClassDeclaration && + node.kind !== SyntaxKind.ConstructorType + ) { + if ( + node.kind !== SyntaxKind.MethodDeclaration && + node.kind !== SyntaxKind.PropertyDeclaration && + node.kind !== SyntaxKind.GetAccessor && + node.kind !== SyntaxKind.SetAccessor + ) { + return grammarErrorOnNode(modifier, Diagnostics.abstract_modifier_can_only_appear_on_a_class_method_or_property_declaration); + } + if (!(node.parent.kind === SyntaxKind.ClassDeclaration && hasSyntacticModifier(node.parent, ModifierFlags.Abstract))) { + const message = node.kind === SyntaxKind.PropertyDeclaration + ? Diagnostics.Abstract_properties_can_only_appear_within_an_abstract_class + : Diagnostics.Abstract_methods_can_only_appear_within_an_abstract_class; + return grammarErrorOnNode(modifier, message); + } + if (flags & ModifierFlags.Static) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "static", "abstract"); + } + if (flags & ModifierFlags.Private) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "private", "abstract"); + } + if (flags & ModifierFlags.Async && lastAsync) { + return grammarErrorOnNode(lastAsync, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "async", "abstract"); + } + if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "abstract", "override"); + } + if (flags & ModifierFlags.Accessor) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "abstract", "accessor"); + } + } + if (isNamedDeclaration(node) && node.name.kind === SyntaxKind.PrivateIdentifier) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_a_private_identifier, "abstract"); + } + + flags |= ModifierFlags.Abstract; + break; + + case SyntaxKind.AsyncKeyword: + if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, "async"); + } + else if (flags & ModifierFlags.Ambient || node.parent.flags & NodeFlags.Ambient) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_in_an_ambient_context, "async"); + } + else if (node.kind === SyntaxKind.Parameter) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_appear_on_a_parameter, "async"); + } + if (flags & ModifierFlags.Abstract) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_cannot_be_used_with_1_modifier, "async", "abstract"); + } + flags |= ModifierFlags.Async; + lastAsync = modifier; + break; + + case SyntaxKind.InKeyword: + case SyntaxKind.OutKeyword: { + const inOutFlag = modifier.kind === SyntaxKind.InKeyword ? ModifierFlags.In : ModifierFlags.Out; + const inOutText = modifier.kind === SyntaxKind.InKeyword ? "in" : "out"; + const parent = isJSDocTemplateTag(node.parent) && (getEffectiveJSDocHost(node.parent) || find(getJSDocRoot(node.parent)?.tags, isJSDocTypedefTag)) || node.parent; + if (node.kind !== SyntaxKind.TypeParameter || parent && !(isInterfaceDeclaration(parent) || isClassLike(parent) || isTypeAliasDeclaration(parent) || isJSDocTypedefTag(parent))) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_can_only_appear_on_a_type_parameter_of_a_class_interface_or_type_alias, inOutText); + } + if (flags & inOutFlag) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_already_seen, inOutText); + } + if (inOutFlag & ModifierFlags.In && flags & ModifierFlags.Out) { + return grammarErrorOnNode(modifier, Diagnostics._0_modifier_must_precede_1_modifier, "in", "out"); + } + flags |= inOutFlag; + break; + } + } + } + } + + if (node.kind === SyntaxKind.Constructor) { + if (flags & ModifierFlags.Static) { + return grammarErrorOnNode(lastStatic!, Diagnostics._0_modifier_cannot_appear_on_a_constructor_declaration, "static"); + } + if (flags & ModifierFlags.Override) { + return grammarErrorOnNode(lastOverride!, Diagnostics._0_modifier_cannot_appear_on_a_constructor_declaration, "override"); // TODO: GH#18217 + } + if (flags & ModifierFlags.Async) { + return grammarErrorOnNode(lastAsync!, Diagnostics._0_modifier_cannot_appear_on_a_constructor_declaration, "async"); + } + return false; + } + else if ((node.kind === SyntaxKind.ImportDeclaration || node.kind === SyntaxKind.ImportEqualsDeclaration) && flags & ModifierFlags.Ambient) { + return grammarErrorOnNode(lastDeclare!, Diagnostics.A_0_modifier_cannot_be_used_with_an_import_declaration, "declare"); + } + else if (node.kind === SyntaxKind.Parameter && (flags & ModifierFlags.ParameterPropertyModifier) && isBindingPattern(node.name)) { + return grammarErrorOnNode(node, Diagnostics.A_parameter_property_may_not_be_declared_using_a_binding_pattern); + } + else if (node.kind === SyntaxKind.Parameter && (flags & ModifierFlags.ParameterPropertyModifier) && node.dotDotDotToken) { + return grammarErrorOnNode(node, Diagnostics.A_parameter_property_cannot_be_declared_using_a_rest_parameter); + } + if (flags & ModifierFlags.Async) { + return checkGrammarAsyncModifier(node, lastAsync!); + } + return false; + } + + /** + * true | false: Early return this value from checkGrammarModifiers. + * undefined: Need to do full checking on the modifiers. + */ + function reportObviousModifierErrors(node: HasModifiers | HasIllegalModifiers): boolean | undefined { + if (!node.modifiers) return false; + + const modifier = findFirstIllegalModifier(node); + return modifier && grammarErrorOnFirstToken(modifier, Diagnostics.Modifiers_cannot_appear_here); + } + + function findFirstModifierExcept(node: HasModifiers, allowedModifier: SyntaxKind): Modifier | undefined { + const modifier = find(node.modifiers, isModifier); + return modifier && modifier.kind !== allowedModifier ? modifier : undefined; + } + + function findFirstIllegalModifier(node: HasModifiers | HasIllegalModifiers): Modifier | undefined { + switch (node.kind) { + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.Constructor: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + case SyntaxKind.IndexSignature: + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.ImportDeclaration: + case SyntaxKind.ImportEqualsDeclaration: + case SyntaxKind.ExportDeclaration: + case SyntaxKind.ExportAssignment: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.Parameter: + case SyntaxKind.TypeParameter: + return undefined; + case SyntaxKind.ClassStaticBlockDeclaration: + case SyntaxKind.PropertyAssignment: + case SyntaxKind.ShorthandPropertyAssignment: + case SyntaxKind.NamespaceExportDeclaration: + case SyntaxKind.MissingDeclaration: + return find(node.modifiers, isModifier); + default: + if (node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { + return undefined; + } + switch (node.kind) { + case SyntaxKind.FunctionDeclaration: + return findFirstModifierExcept(node, SyntaxKind.AsyncKeyword); + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ConstructorType: + return findFirstModifierExcept(node, SyntaxKind.AbstractKeyword); + case SyntaxKind.ClassExpression: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + return find(node.modifiers, isModifier); + case SyntaxKind.VariableStatement: + return node.declarationList.flags & NodeFlags.Using ? + findFirstModifierExcept(node, SyntaxKind.AwaitKeyword) : + find(node.modifiers, isModifier); + case SyntaxKind.EnumDeclaration: + return findFirstModifierExcept(node, SyntaxKind.ConstKeyword); + default: + Debug.assertNever(node); + } + } + } + + function reportObviousDecoratorErrors(node: HasModifiers | HasDecorators | HasIllegalModifiers | HasIllegalDecorators) { + const decorator = findFirstIllegalDecorator(node); + return decorator && grammarErrorOnFirstToken(decorator, Diagnostics.Decorators_are_not_valid_here); + } + + function findFirstIllegalDecorator(node: HasModifiers | HasDecorators | HasIllegalModifiers | HasIllegalDecorators): Decorator | undefined { + return canHaveIllegalDecorators(node) ? find(node.modifiers, isDecorator) : undefined; + } + + function checkGrammarAsyncModifier(node: Node, asyncModifier: Node): boolean { + switch (node.kind) { + case SyntaxKind.MethodDeclaration: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + return false; + } + + return grammarErrorOnNode(asyncModifier, Diagnostics._0_modifier_cannot_be_used_here, "async"); + } + + function checkGrammarForDisallowedTrailingComma(list: NodeArray | undefined, diag = Diagnostics.Trailing_comma_not_allowed): boolean { + if (list && list.hasTrailingComma) { + return grammarErrorAtPos(list[0], list.end - ",".length, ",".length, diag); + } + return false; + } + + function checkGrammarTypeParameterList(typeParameters: NodeArray | undefined, file: SourceFile): boolean { + if (typeParameters && typeParameters.length === 0) { + const start = typeParameters.pos - "<".length; + const end = skipTrivia(file.text, typeParameters.end) + ">".length; + return grammarErrorAtPos(file, start, end - start, Diagnostics.Type_parameter_list_cannot_be_empty); + } + return false; + } + + function checkGrammarParameterList(parameters: NodeArray) { + let seenOptionalParameter = false; + const parameterCount = parameters.length; + + for (let i = 0; i < parameterCount; i++) { + const parameter = parameters[i]; + if (parameter.dotDotDotToken) { + if (i !== (parameterCount - 1)) { + return grammarErrorOnNode(parameter.dotDotDotToken, Diagnostics.A_rest_parameter_must_be_last_in_a_parameter_list); + } + if (!(parameter.flags & NodeFlags.Ambient)) { // Allow `...foo,` in ambient declarations; see GH#23070 + checkGrammarForDisallowedTrailingComma(parameters, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + } + + if (parameter.questionToken) { + return grammarErrorOnNode(parameter.questionToken, Diagnostics.A_rest_parameter_cannot_be_optional); + } + + if (parameter.initializer) { + return grammarErrorOnNode(parameter.name, Diagnostics.A_rest_parameter_cannot_have_an_initializer); + } + } + else if (hasEffectiveQuestionToken(parameter)) { + seenOptionalParameter = true; + if (parameter.questionToken && parameter.initializer) { + return grammarErrorOnNode(parameter.name, Diagnostics.Parameter_cannot_have_question_mark_and_initializer); + } + } + else if (seenOptionalParameter && !parameter.initializer) { + return grammarErrorOnNode(parameter.name, Diagnostics.A_required_parameter_cannot_follow_an_optional_parameter); + } + } + } + + function getNonSimpleParameters(parameters: readonly ParameterDeclaration[]): readonly ParameterDeclaration[] { + return filter(parameters, parameter => !!parameter.initializer || isBindingPattern(parameter.name) || isRestParameter(parameter)); + } + + function checkGrammarForUseStrictSimpleParameterList(node: FunctionLikeDeclaration): boolean { + if (languageVersion >= ScriptTarget.ES2016) { + const useStrictDirective = node.body && isBlock(node.body) && findUseStrictPrologue(node.body.statements); + if (useStrictDirective) { + const nonSimpleParameters = getNonSimpleParameters(node.parameters); + if (length(nonSimpleParameters)) { + forEach(nonSimpleParameters, parameter => { + addRelatedInfo( + error(parameter, Diagnostics.This_parameter_is_not_allowed_with_use_strict_directive), + createDiagnosticForNode(useStrictDirective, Diagnostics.use_strict_directive_used_here), + ); + }); + + const diagnostics = nonSimpleParameters.map((parameter, index) => ( + index === 0 ? createDiagnosticForNode(parameter, Diagnostics.Non_simple_parameter_declared_here) : createDiagnosticForNode(parameter, Diagnostics.and_here) + )) as [DiagnosticWithLocation, ...DiagnosticWithLocation[]]; + addRelatedInfo(error(useStrictDirective, Diagnostics.use_strict_directive_cannot_be_used_with_non_simple_parameter_list), ...diagnostics); + return true; + } + } + } + return false; + } + + function checkGrammarFunctionLikeDeclaration(node: FunctionLikeDeclaration | MethodSignature): boolean { + // Prevent cascading error by short-circuit + const file = getSourceFileOfNode(node); + return checkGrammarModifiers(node) || + checkGrammarTypeParameterList(node.typeParameters, file) || + checkGrammarParameterList(node.parameters) || + checkGrammarArrowFunction(node, file) || + (isFunctionLikeDeclaration(node) && checkGrammarForUseStrictSimpleParameterList(node)); + } + + function checkGrammarClassLikeDeclaration(node: ClassLikeDeclaration): boolean { + const file = getSourceFileOfNode(node); + return checkGrammarClassDeclarationHeritageClauses(node) || + checkGrammarTypeParameterList(node.typeParameters, file); + } + + function checkGrammarArrowFunction(node: Node, file: SourceFile): boolean { + if (!isArrowFunction(node)) { + return false; + } + + if (node.typeParameters && !(length(node.typeParameters) > 1 || node.typeParameters.hasTrailingComma || node.typeParameters[0].constraint)) { + if (file && fileExtensionIsOneOf(file.fileName, [Extension.Mts, Extension.Cts])) { + grammarErrorOnNode(node.typeParameters[0], Diagnostics.This_syntax_is_reserved_in_files_with_the_mts_or_cts_extension_Add_a_trailing_comma_or_explicit_constraint); + } + } + + const { equalsGreaterThanToken } = node; + const startLine = getLineAndCharacterOfPosition(file, equalsGreaterThanToken.pos).line; + const endLine = getLineAndCharacterOfPosition(file, equalsGreaterThanToken.end).line; + return startLine !== endLine && grammarErrorOnNode(equalsGreaterThanToken, Diagnostics.Line_terminator_not_permitted_before_arrow); + } + + function checkGrammarIndexSignatureParameters(node: SignatureDeclaration): boolean { + const parameter = node.parameters[0]; + if (node.parameters.length !== 1) { + if (parameter) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_must_have_exactly_one_parameter); + } + else { + return grammarErrorOnNode(node, Diagnostics.An_index_signature_must_have_exactly_one_parameter); + } + } + checkGrammarForDisallowedTrailingComma(node.parameters, Diagnostics.An_index_signature_cannot_have_a_trailing_comma); + if (parameter.dotDotDotToken) { + return grammarErrorOnNode(parameter.dotDotDotToken, Diagnostics.An_index_signature_cannot_have_a_rest_parameter); + } + if (hasEffectiveModifiers(parameter)) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_cannot_have_an_accessibility_modifier); + } + if (parameter.questionToken) { + return grammarErrorOnNode(parameter.questionToken, Diagnostics.An_index_signature_parameter_cannot_have_a_question_mark); + } + if (parameter.initializer) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_cannot_have_an_initializer); + } + if (!parameter.type) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_must_have_a_type_annotation); + } + const type = getTypeFromTypeNode(parameter.type); + if (someType(type, t => !!(t.flags & TypeFlags.StringOrNumberLiteralOrUnique)) || isGenericType(type)) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_type_cannot_be_a_literal_type_or_generic_type_Consider_using_a_mapped_object_type_instead); + } + if (!everyType(type, isValidIndexKeyType)) { + return grammarErrorOnNode(parameter.name, Diagnostics.An_index_signature_parameter_type_must_be_string_number_symbol_or_a_template_literal_type); + } + if (!node.type) { + return grammarErrorOnNode(node, Diagnostics.An_index_signature_must_have_a_type_annotation); + } + return false; + } + + function checkGrammarIndexSignature(node: IndexSignatureDeclaration) { + // Prevent cascading error by short-circuit + return checkGrammarModifiers(node) || checkGrammarIndexSignatureParameters(node); + } + + function checkGrammarForAtLeastOneTypeArgument(node: Node, typeArguments: NodeArray | undefined): boolean { + if (typeArguments && typeArguments.length === 0) { + const sourceFile = getSourceFileOfNode(node); + const start = typeArguments.pos - "<".length; + const end = skipTrivia(sourceFile.text, typeArguments.end) + ">".length; + return grammarErrorAtPos(sourceFile, start, end - start, Diagnostics.Type_argument_list_cannot_be_empty); + } + return false; + } + + function checkGrammarTypeArguments(node: Node, typeArguments: NodeArray | undefined): boolean { + return checkGrammarForDisallowedTrailingComma(typeArguments) || + checkGrammarForAtLeastOneTypeArgument(node, typeArguments); + } + + function checkGrammarTaggedTemplateChain(node: TaggedTemplateExpression): boolean { + if (node.questionDotToken || node.flags & NodeFlags.OptionalChain) { + return grammarErrorOnNode(node.template, Diagnostics.Tagged_template_expressions_are_not_permitted_in_an_optional_chain); + } + return false; + } + + function checkGrammarHeritageClause(node: HeritageClause): boolean { + const types = node.types; + if (checkGrammarForDisallowedTrailingComma(types)) { + return true; + } + if (types && types.length === 0) { + const listType = tokenToString(node.token); + return grammarErrorAtPos(node, types.pos, 0, Diagnostics._0_list_cannot_be_empty, listType); + } + return some(types, checkGrammarExpressionWithTypeArguments); + } + + function checkGrammarExpressionWithTypeArguments(node: ExpressionWithTypeArguments | TypeQueryNode) { + if (isExpressionWithTypeArguments(node) && isImportKeyword(node.expression) && node.typeArguments) { + return grammarErrorOnNode(node, Diagnostics.This_use_of_import_is_invalid_import_calls_can_be_written_but_they_must_have_parentheses_and_cannot_have_type_arguments); + } + return checkGrammarTypeArguments(node, node.typeArguments); + } + + function checkGrammarClassDeclarationHeritageClauses(node: ClassLikeDeclaration) { + let seenExtendsClause = false; + let seenImplementsClause = false; + + if (!checkGrammarModifiers(node) && node.heritageClauses) { + for (const heritageClause of node.heritageClauses) { + if (heritageClause.token === SyntaxKind.ExtendsKeyword) { + if (seenExtendsClause) { + return grammarErrorOnFirstToken(heritageClause, Diagnostics.extends_clause_already_seen); + } + + if (seenImplementsClause) { + return grammarErrorOnFirstToken(heritageClause, Diagnostics.extends_clause_must_precede_implements_clause); + } + + if (heritageClause.types.length > 1) { + return grammarErrorOnFirstToken(heritageClause.types[1], Diagnostics.Classes_can_only_extend_a_single_class); + } + + seenExtendsClause = true; + } + else { + Debug.assert(heritageClause.token === SyntaxKind.ImplementsKeyword); + if (seenImplementsClause) { + return grammarErrorOnFirstToken(heritageClause, Diagnostics.implements_clause_already_seen); + } + + seenImplementsClause = true; + } + + // Grammar checking heritageClause inside class declaration + checkGrammarHeritageClause(heritageClause); + } + } + } + + function checkGrammarInterfaceDeclaration(node: InterfaceDeclaration) { + let seenExtendsClause = false; + + if (node.heritageClauses) { + for (const heritageClause of node.heritageClauses) { + if (heritageClause.token === SyntaxKind.ExtendsKeyword) { + if (seenExtendsClause) { + return grammarErrorOnFirstToken(heritageClause, Diagnostics.extends_clause_already_seen); + } + + seenExtendsClause = true; + } + else { + Debug.assert(heritageClause.token === SyntaxKind.ImplementsKeyword); + return grammarErrorOnFirstToken(heritageClause, Diagnostics.Interface_declaration_cannot_have_implements_clause); + } + + // Grammar checking heritageClause inside class declaration + checkGrammarHeritageClause(heritageClause); + } + } + return false; + } + + function checkGrammarComputedPropertyName(node: Node): boolean { + // If node is not a computedPropertyName, just skip the grammar checking + if (node.kind !== SyntaxKind.ComputedPropertyName) { + return false; + } + + const computedPropertyName = node as ComputedPropertyName; + if (computedPropertyName.expression.kind === SyntaxKind.BinaryExpression && (computedPropertyName.expression as BinaryExpression).operatorToken.kind === SyntaxKind.CommaToken) { + return grammarErrorOnNode(computedPropertyName.expression, Diagnostics.A_comma_expression_is_not_allowed_in_a_computed_property_name); + } + return false; + } + + function checkGrammarForGenerator(node: FunctionLikeDeclaration) { + if (node.asteriskToken) { + Debug.assert( + node.kind === SyntaxKind.FunctionDeclaration || + node.kind === SyntaxKind.FunctionExpression || + node.kind === SyntaxKind.MethodDeclaration, + ); + if (node.flags & NodeFlags.Ambient) { + return grammarErrorOnNode(node.asteriskToken, Diagnostics.Generators_are_not_allowed_in_an_ambient_context); + } + if (!node.body) { + return grammarErrorOnNode(node.asteriskToken, Diagnostics.An_overload_signature_cannot_be_declared_as_a_generator); + } + } + } + + function checkGrammarForInvalidQuestionMark(questionToken: QuestionToken | undefined, message: DiagnosticMessage): boolean { + return !!questionToken && grammarErrorOnNode(questionToken, message); + } + + function checkGrammarForInvalidExclamationToken(exclamationToken: ExclamationToken | undefined, message: DiagnosticMessage): boolean { + return !!exclamationToken && grammarErrorOnNode(exclamationToken, message); + } + + function checkGrammarObjectLiteralExpression(node: ObjectLiteralExpression, inDestructuring: boolean) { + const seen = new Map<__String, DeclarationMeaning>(); + + for (const prop of node.properties) { + if (prop.kind === SyntaxKind.SpreadAssignment) { + if (inDestructuring) { + // a rest property cannot be destructured any further + const expression = skipParentheses(prop.expression); + if (isArrayLiteralExpression(expression) || isObjectLiteralExpression(expression)) { + return grammarErrorOnNode(prop.expression, Diagnostics.A_rest_element_cannot_contain_a_binding_pattern); + } + } + continue; + } + const name = prop.name; + if (name.kind === SyntaxKind.ComputedPropertyName) { + // If the name is not a ComputedPropertyName, the grammar checking will skip it + checkGrammarComputedPropertyName(name); + } + + if (prop.kind === SyntaxKind.ShorthandPropertyAssignment && !inDestructuring && prop.objectAssignmentInitializer) { + // having objectAssignmentInitializer is only valid in ObjectAssignmentPattern + // outside of destructuring it is a syntax error + grammarErrorOnNode(prop.equalsToken!, Diagnostics.Did_you_mean_to_use_a_Colon_An_can_only_follow_a_property_name_when_the_containing_object_literal_is_part_of_a_destructuring_pattern); + } + + if (name.kind === SyntaxKind.PrivateIdentifier) { + grammarErrorOnNode(name, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + + // Modifiers are never allowed on properties except for 'async' on a method declaration + if (canHaveModifiers(prop) && prop.modifiers) { + for (const mod of prop.modifiers) { + if (isModifier(mod) && (mod.kind !== SyntaxKind.AsyncKeyword || prop.kind !== SyntaxKind.MethodDeclaration)) { + grammarErrorOnNode(mod, Diagnostics._0_modifier_cannot_be_used_here, getTextOfNode(mod)); + } + } + } + else if (canHaveIllegalModifiers(prop) && prop.modifiers) { + for (const mod of prop.modifiers) { + if (isModifier(mod)) { + grammarErrorOnNode(mod, Diagnostics._0_modifier_cannot_be_used_here, getTextOfNode(mod)); + } + } + } + + // ECMA-262 11.1.5 Object Initializer + // If previous is not undefined then throw a SyntaxError exception if any of the following conditions are true + // a.This production is contained in strict code and IsDataDescriptor(previous) is true and + // IsDataDescriptor(propId.descriptor) is true. + // b.IsDataDescriptor(previous) is true and IsAccessorDescriptor(propId.descriptor) is true. + // c.IsAccessorDescriptor(previous) is true and IsDataDescriptor(propId.descriptor) is true. + // d.IsAccessorDescriptor(previous) is true and IsAccessorDescriptor(propId.descriptor) is true + // and either both previous and propId.descriptor have[[Get]] fields or both previous and propId.descriptor have[[Set]] fields + let currentKind: DeclarationMeaning; + switch (prop.kind) { + case SyntaxKind.ShorthandPropertyAssignment: + case SyntaxKind.PropertyAssignment: + // Grammar checking for computedPropertyName and shorthandPropertyAssignment + checkGrammarForInvalidExclamationToken(prop.exclamationToken, Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context); + checkGrammarForInvalidQuestionMark(prop.questionToken, Diagnostics.An_object_member_cannot_be_declared_optional); + if (name.kind === SyntaxKind.NumericLiteral) { + checkGrammarNumericLiteral(name); + } + currentKind = DeclarationMeaning.PropertyAssignment; + break; + case SyntaxKind.MethodDeclaration: + currentKind = DeclarationMeaning.Method; + break; + case SyntaxKind.GetAccessor: + currentKind = DeclarationMeaning.GetAccessor; + break; + case SyntaxKind.SetAccessor: + currentKind = DeclarationMeaning.SetAccessor; + break; + default: + Debug.assertNever(prop, "Unexpected syntax kind:" + (prop as Node).kind); + } + + if (!inDestructuring) { + const effectiveName = getEffectivePropertyNameForPropertyNameNode(name); + if (effectiveName === undefined) { + continue; + } + + const existingKind = seen.get(effectiveName); + if (!existingKind) { + seen.set(effectiveName, currentKind); + } + else { + if ((currentKind & DeclarationMeaning.Method) && (existingKind & DeclarationMeaning.Method)) { + grammarErrorOnNode(name, Diagnostics.Duplicate_identifier_0, getTextOfNode(name)); + } + else if ((currentKind & DeclarationMeaning.PropertyAssignment) && (existingKind & DeclarationMeaning.PropertyAssignment)) { + grammarErrorOnNode(name, Diagnostics.An_object_literal_cannot_have_multiple_properties_with_the_same_name, getTextOfNode(name)); + } + else if ((currentKind & DeclarationMeaning.GetOrSetAccessor) && (existingKind & DeclarationMeaning.GetOrSetAccessor)) { + if (existingKind !== DeclarationMeaning.GetOrSetAccessor && currentKind !== existingKind) { + seen.set(effectiveName, currentKind | existingKind); + } + else { + return grammarErrorOnNode(name, Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name); + } + } + else { + return grammarErrorOnNode(name, Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name); + } + } + } + } + } + + function checkGrammarJsxElement(node: JsxOpeningLikeElement) { + checkGrammarJsxName(node.tagName); + checkGrammarTypeArguments(node, node.typeArguments); + const seen = new Map<__String, boolean>(); + + for (const attr of node.attributes.properties) { + if (attr.kind === SyntaxKind.JsxSpreadAttribute) { + continue; + } + + const { name, initializer } = attr; + const escapedText = getEscapedTextOfJsxAttributeName(name); + if (!seen.get(escapedText)) { + seen.set(escapedText, true); + } + else { + return grammarErrorOnNode(name, Diagnostics.JSX_elements_cannot_have_multiple_attributes_with_the_same_name); + } + + if (initializer && initializer.kind === SyntaxKind.JsxExpression && !initializer.expression) { + return grammarErrorOnNode(initializer, Diagnostics.JSX_attributes_must_only_be_assigned_a_non_empty_expression); + } + } + } + + function checkGrammarJsxName(node: JsxTagNameExpression) { + if (isPropertyAccessExpression(node) && isJsxNamespacedName(node.expression)) { + return grammarErrorOnNode(node.expression, Diagnostics.JSX_property_access_expressions_cannot_include_JSX_namespace_names); + } + if (isJsxNamespacedName(node) && getJSXTransformEnabled(compilerOptions) && !isIntrinsicJsxName(node.namespace.escapedText)) { + return grammarErrorOnNode(node, Diagnostics.React_components_cannot_include_JSX_namespace_names); + } + } + + function checkGrammarJsxExpression(node: JsxExpression) { + if (node.expression && isCommaSequence(node.expression)) { + return grammarErrorOnNode(node.expression, Diagnostics.JSX_expressions_may_not_use_the_comma_operator_Did_you_mean_to_write_an_array); + } + } + + function checkGrammarForInOrForOfStatement(forInOrOfStatement: ForInOrOfStatement): boolean { + if (checkGrammarStatementInAmbientContext(forInOrOfStatement)) { + return true; + } + + if (forInOrOfStatement.kind === SyntaxKind.ForOfStatement && forInOrOfStatement.awaitModifier) { + if (!(forInOrOfStatement.flags & NodeFlags.AwaitContext)) { + const sourceFile = getSourceFileOfNode(forInOrOfStatement); + if (isInTopLevelContext(forInOrOfStatement)) { + if (!hasParseDiagnostics(sourceFile)) { + if (!isEffectiveExternalModule(sourceFile, compilerOptions)) { + diagnostics.add(createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.for_await_loops_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module)); + } + switch (moduleKind) { + case ModuleKind.Node16: + case ModuleKind.NodeNext: + if (sourceFile.impliedNodeFormat === ModuleKind.CommonJS) { + diagnostics.add( + createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.The_current_file_is_a_CommonJS_module_and_cannot_use_await_at_the_top_level), + ); + break; + } + // fallthrough + case ModuleKind.ES2022: + case ModuleKind.ESNext: + case ModuleKind.System: + if (languageVersion >= ScriptTarget.ES2017) { + break; + } + // fallthrough + default: + diagnostics.add( + createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.Top_level_for_await_loops_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_nodenext_or_preserve_and_the_target_option_is_set_to_es2017_or_higher), + ); + break; + } + } + } + else { + // use of 'for-await-of' in non-async function + if (!hasParseDiagnostics(sourceFile)) { + const diagnostic = createDiagnosticForNode(forInOrOfStatement.awaitModifier, Diagnostics.for_await_loops_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules); + const func = getContainingFunction(forInOrOfStatement); + if (func && func.kind !== SyntaxKind.Constructor) { + Debug.assert((getFunctionFlags(func) & FunctionFlags.Async) === 0, "Enclosing function should never be an async function."); + const relatedInfo = createDiagnosticForNode(func, Diagnostics.Did_you_mean_to_mark_this_function_as_async); + addRelatedInfo(diagnostic, relatedInfo); + } + diagnostics.add(diagnostic); + return true; + } + } + } + } + + if ( + isForOfStatement(forInOrOfStatement) && !(forInOrOfStatement.flags & NodeFlags.AwaitContext) && + isIdentifier(forInOrOfStatement.initializer) && forInOrOfStatement.initializer.escapedText === "async" + ) { + grammarErrorOnNode(forInOrOfStatement.initializer, Diagnostics.The_left_hand_side_of_a_for_of_statement_may_not_be_async); + return false; + } + + if (forInOrOfStatement.initializer.kind === SyntaxKind.VariableDeclarationList) { + const variableList = forInOrOfStatement.initializer as VariableDeclarationList; + if (!checkGrammarVariableDeclarationList(variableList)) { + const declarations = variableList.declarations; + + // declarations.length can be zero if there is an error in variable declaration in for-of or for-in + // See http://www.ecma-international.org/ecma-262/6.0/#sec-for-in-and-for-of-statements for details + // For example: + // var let = 10; + // for (let of [1,2,3]) {} // this is invalid ES6 syntax + // for (let in [1,2,3]) {} // this is invalid ES6 syntax + // We will then want to skip on grammar checking on variableList declaration + if (!declarations.length) { + return false; + } + + if (declarations.length > 1) { + const diagnostic = forInOrOfStatement.kind === SyntaxKind.ForInStatement + ? Diagnostics.Only_a_single_variable_declaration_is_allowed_in_a_for_in_statement + : Diagnostics.Only_a_single_variable_declaration_is_allowed_in_a_for_of_statement; + return grammarErrorOnFirstToken(variableList.declarations[1], diagnostic); + } + const firstDeclaration = declarations[0]; + + if (firstDeclaration.initializer) { + const diagnostic = forInOrOfStatement.kind === SyntaxKind.ForInStatement + ? Diagnostics.The_variable_declaration_of_a_for_in_statement_cannot_have_an_initializer + : Diagnostics.The_variable_declaration_of_a_for_of_statement_cannot_have_an_initializer; + return grammarErrorOnNode(firstDeclaration.name, diagnostic); + } + if (firstDeclaration.type) { + const diagnostic = forInOrOfStatement.kind === SyntaxKind.ForInStatement + ? Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_use_a_type_annotation + : Diagnostics.The_left_hand_side_of_a_for_of_statement_cannot_use_a_type_annotation; + return grammarErrorOnNode(firstDeclaration, diagnostic); + } + } + } + + return false; + } + + function checkGrammarAccessor(accessor: AccessorDeclaration): boolean { + if (!(accessor.flags & NodeFlags.Ambient) && (accessor.parent.kind !== SyntaxKind.TypeLiteral) && (accessor.parent.kind !== SyntaxKind.InterfaceDeclaration)) { + if (languageVersion < ScriptTarget.ES2015 && isPrivateIdentifier(accessor.name)) { + return grammarErrorOnNode(accessor.name, Diagnostics.Private_identifiers_are_only_available_when_targeting_ECMAScript_2015_and_higher); + } + if (accessor.body === undefined && !hasSyntacticModifier(accessor, ModifierFlags.Abstract)) { + return grammarErrorAtPos(accessor, accessor.end - 1, ";".length, Diagnostics._0_expected, "{"); + } + } + if (accessor.body) { + if (hasSyntacticModifier(accessor, ModifierFlags.Abstract)) { + return grammarErrorOnNode(accessor, Diagnostics.An_abstract_accessor_cannot_have_an_implementation); + } + if (accessor.parent.kind === SyntaxKind.TypeLiteral || accessor.parent.kind === SyntaxKind.InterfaceDeclaration) { + return grammarErrorOnNode(accessor.body, Diagnostics.An_implementation_cannot_be_declared_in_ambient_contexts); + } + } + if (accessor.typeParameters) { + return grammarErrorOnNode(accessor.name, Diagnostics.An_accessor_cannot_have_type_parameters); + } + if (!doesAccessorHaveCorrectParameterCount(accessor)) { + return grammarErrorOnNode( + accessor.name, + accessor.kind === SyntaxKind.GetAccessor ? + Diagnostics.A_get_accessor_cannot_have_parameters : + Diagnostics.A_set_accessor_must_have_exactly_one_parameter, + ); + } + if (accessor.kind === SyntaxKind.SetAccessor) { + if (accessor.type) { + return grammarErrorOnNode(accessor.name, Diagnostics.A_set_accessor_cannot_have_a_return_type_annotation); + } + const parameter = Debug.checkDefined(getSetAccessorValueParameter(accessor), "Return value does not match parameter count assertion."); + if (parameter.dotDotDotToken) { + return grammarErrorOnNode(parameter.dotDotDotToken, Diagnostics.A_set_accessor_cannot_have_rest_parameter); + } + if (parameter.questionToken) { + return grammarErrorOnNode(parameter.questionToken, Diagnostics.A_set_accessor_cannot_have_an_optional_parameter); + } + if (parameter.initializer) { + return grammarErrorOnNode(accessor.name, Diagnostics.A_set_accessor_parameter_cannot_have_an_initializer); + } + } + return false; + } + + /** Does the accessor have the right number of parameters? + * A get accessor has no parameters or a single `this` parameter. + * A set accessor has one parameter or a `this` parameter and one more parameter. + */ + function doesAccessorHaveCorrectParameterCount(accessor: AccessorDeclaration) { + return getAccessorThisParameter(accessor) || accessor.parameters.length === (accessor.kind === SyntaxKind.GetAccessor ? 0 : 1); + } + + function getAccessorThisParameter(accessor: AccessorDeclaration): ParameterDeclaration | undefined { + if (accessor.parameters.length === (accessor.kind === SyntaxKind.GetAccessor ? 1 : 2)) { + return getThisParameter(accessor); + } + } + + function checkGrammarTypeOperatorNode(node: TypeOperatorNode) { + if (node.operator === SyntaxKind.UniqueKeyword) { + if (node.type.kind !== SyntaxKind.SymbolKeyword) { + return grammarErrorOnNode(node.type, Diagnostics._0_expected, tokenToString(SyntaxKind.SymbolKeyword)); + } + let parent = walkUpParenthesizedTypes(node.parent); + if (isInJSFile(parent) && isJSDocTypeExpression(parent)) { + const host = getJSDocHost(parent); + if (host) { + parent = getSingleVariableOfVariableStatement(host) || host; + } + } + switch (parent.kind) { + case SyntaxKind.VariableDeclaration: + const decl = parent as VariableDeclaration; + if (decl.name.kind !== SyntaxKind.Identifier) { + return grammarErrorOnNode(node, Diagnostics.unique_symbol_types_may_not_be_used_on_a_variable_declaration_with_a_binding_name); + } + if (!isVariableDeclarationInVariableStatement(decl)) { + return grammarErrorOnNode(node, Diagnostics.unique_symbol_types_are_only_allowed_on_variables_in_a_variable_statement); + } + if (!(decl.parent.flags & NodeFlags.Const)) { + return grammarErrorOnNode((parent as VariableDeclaration).name, Diagnostics.A_variable_whose_type_is_a_unique_symbol_type_must_be_const); + } + break; + + case SyntaxKind.PropertyDeclaration: + if ( + !isStatic(parent) || + !hasEffectiveReadonlyModifier(parent) + ) { + return grammarErrorOnNode((parent as PropertyDeclaration).name, Diagnostics.A_property_of_a_class_whose_type_is_a_unique_symbol_type_must_be_both_static_and_readonly); + } + break; + + case SyntaxKind.PropertySignature: + if (!hasSyntacticModifier(parent, ModifierFlags.Readonly)) { + return grammarErrorOnNode((parent as PropertySignature).name, Diagnostics.A_property_of_an_interface_or_type_literal_whose_type_is_a_unique_symbol_type_must_be_readonly); + } + break; + + default: + return grammarErrorOnNode(node, Diagnostics.unique_symbol_types_are_not_allowed_here); + } + } + else if (node.operator === SyntaxKind.ReadonlyKeyword) { + if (node.type.kind !== SyntaxKind.ArrayType && node.type.kind !== SyntaxKind.TupleType) { + return grammarErrorOnFirstToken(node, Diagnostics.readonly_type_modifier_is_only_permitted_on_array_and_tuple_literal_types, tokenToString(SyntaxKind.SymbolKeyword)); + } + } + } + + function checkGrammarForInvalidDynamicName(node: DeclarationName, message: DiagnosticMessage) { + if (isNonBindableDynamicName(node)) { + return grammarErrorOnNode(node, message); + } + } + + function checkGrammarMethod(node: MethodDeclaration | MethodSignature) { + if (checkGrammarFunctionLikeDeclaration(node)) { + return true; + } + + if (node.kind === SyntaxKind.MethodDeclaration) { + if (node.parent.kind === SyntaxKind.ObjectLiteralExpression) { + // We only disallow modifier on a method declaration if it is a property of object-literal-expression + if (node.modifiers && !(node.modifiers.length === 1 && first(node.modifiers).kind === SyntaxKind.AsyncKeyword)) { + return grammarErrorOnFirstToken(node, Diagnostics.Modifiers_cannot_appear_here); + } + else if (checkGrammarForInvalidQuestionMark(node.questionToken, Diagnostics.An_object_member_cannot_be_declared_optional)) { + return true; + } + else if (checkGrammarForInvalidExclamationToken(node.exclamationToken, Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context)) { + return true; + } + else if (node.body === undefined) { + return grammarErrorAtPos(node, node.end - 1, ";".length, Diagnostics._0_expected, "{"); + } + } + if (checkGrammarForGenerator(node)) { + return true; + } + } + + if (isClassLike(node.parent)) { + if (languageVersion < ScriptTarget.ES2015 && isPrivateIdentifier(node.name)) { + return grammarErrorOnNode(node.name, Diagnostics.Private_identifiers_are_only_available_when_targeting_ECMAScript_2015_and_higher); + } + // Technically, computed properties in ambient contexts is disallowed + // for property declarations and accessors too, not just methods. + // However, property declarations disallow computed names in general, + // and accessors are not allowed in ambient contexts in general, + // so this error only really matters for methods. + if (node.flags & NodeFlags.Ambient) { + return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_an_ambient_context_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); + } + else if (node.kind === SyntaxKind.MethodDeclaration && !node.body) { + return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_method_overload_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); + } + } + else if (node.parent.kind === SyntaxKind.InterfaceDeclaration) { + return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_an_interface_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); + } + else if (node.parent.kind === SyntaxKind.TypeLiteral) { + return checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_type_literal_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type); + } + } + + function checkGrammarBreakOrContinueStatement(node: BreakOrContinueStatement): boolean { + let current: Node = node; + while (current) { + if (isFunctionLikeOrClassStaticBlockDeclaration(current)) { + return grammarErrorOnNode(node, Diagnostics.Jump_target_cannot_cross_function_boundary); + } + + switch (current.kind) { + case SyntaxKind.LabeledStatement: + if (node.label && (current as LabeledStatement).label.escapedText === node.label.escapedText) { + // found matching label - verify that label usage is correct + // continue can only target labels that are on iteration statements + const isMisplacedContinueLabel = node.kind === SyntaxKind.ContinueStatement + && !isIterationStatement((current as LabeledStatement).statement, /*lookInLabeledStatements*/ true); + + if (isMisplacedContinueLabel) { + return grammarErrorOnNode(node, Diagnostics.A_continue_statement_can_only_jump_to_a_label_of_an_enclosing_iteration_statement); + } + + return false; + } + break; + case SyntaxKind.SwitchStatement: + if (node.kind === SyntaxKind.BreakStatement && !node.label) { + // unlabeled break within switch statement - ok + return false; + } + break; + default: + if (isIterationStatement(current, /*lookInLabeledStatements*/ false) && !node.label) { + // unlabeled break or continue within iteration statement - ok + return false; + } + break; + } + + current = current.parent; + } + + if (node.label) { + const message = node.kind === SyntaxKind.BreakStatement + ? Diagnostics.A_break_statement_can_only_jump_to_a_label_of_an_enclosing_statement + : Diagnostics.A_continue_statement_can_only_jump_to_a_label_of_an_enclosing_iteration_statement; + + return grammarErrorOnNode(node, message); + } + else { + const message = node.kind === SyntaxKind.BreakStatement + ? Diagnostics.A_break_statement_can_only_be_used_within_an_enclosing_iteration_or_switch_statement + : Diagnostics.A_continue_statement_can_only_be_used_within_an_enclosing_iteration_statement; + return grammarErrorOnNode(node, message); + } + } + + function checkGrammarBindingElement(node: BindingElement) { + if (node.dotDotDotToken) { + const elements = node.parent.elements; + if (node !== last(elements)) { + return grammarErrorOnNode(node, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); + } + checkGrammarForDisallowedTrailingComma(elements, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + + if (node.propertyName) { + return grammarErrorOnNode(node.name, Diagnostics.A_rest_element_cannot_have_a_property_name); + } + } + + if (node.dotDotDotToken && node.initializer) { + // Error on equals token which immediately precedes the initializer + return grammarErrorAtPos(node, node.initializer.pos - 1, 1, Diagnostics.A_rest_element_cannot_have_an_initializer); + } + } + + function isStringOrNumberLiteralExpression(expr: Expression) { + return isStringOrNumericLiteralLike(expr) || + expr.kind === SyntaxKind.PrefixUnaryExpression && (expr as PrefixUnaryExpression).operator === SyntaxKind.MinusToken && + (expr as PrefixUnaryExpression).operand.kind === SyntaxKind.NumericLiteral; + } + + function isBigIntLiteralExpression(expr: Expression) { + return expr.kind === SyntaxKind.BigIntLiteral || + expr.kind === SyntaxKind.PrefixUnaryExpression && (expr as PrefixUnaryExpression).operator === SyntaxKind.MinusToken && + (expr as PrefixUnaryExpression).operand.kind === SyntaxKind.BigIntLiteral; + } + + function isSimpleLiteralEnumReference(expr: Expression) { + if ( + (isPropertyAccessExpression(expr) || (isElementAccessExpression(expr) && isStringOrNumberLiteralExpression(expr.argumentExpression))) && + isEntityNameExpression(expr.expression) + ) { + return !!(checkExpressionCached(expr).flags & TypeFlags.EnumLike); + } + } + + function checkAmbientInitializer(node: VariableDeclaration | PropertyDeclaration | PropertySignature) { + const initializer = node.initializer; + if (initializer) { + const isInvalidInitializer = !( + isStringOrNumberLiteralExpression(initializer) || + isSimpleLiteralEnumReference(initializer) || + initializer.kind === SyntaxKind.TrueKeyword || initializer.kind === SyntaxKind.FalseKeyword || + isBigIntLiteralExpression(initializer) + ); + const isConstOrReadonly = isDeclarationReadonly(node) || isVariableDeclaration(node) && (isVarConstLike(node)); + if (isConstOrReadonly && !node.type) { + if (isInvalidInitializer) { + return grammarErrorOnNode(initializer, Diagnostics.A_const_initializer_in_an_ambient_context_must_be_a_string_or_numeric_literal_or_literal_enum_reference); + } + } + else { + return grammarErrorOnNode(initializer, Diagnostics.Initializers_are_not_allowed_in_ambient_contexts); + } + } + } + + function checkGrammarVariableDeclaration(node: VariableDeclaration) { + const nodeFlags = getCombinedNodeFlagsCached(node); + const blockScopeKind = nodeFlags & NodeFlags.BlockScoped; + if (isBindingPattern(node.name)) { + switch (blockScopeKind) { + case NodeFlags.AwaitUsing: + return grammarErrorOnNode(node, Diagnostics._0_declarations_may_not_have_binding_patterns, "await using"); + case NodeFlags.Using: + return grammarErrorOnNode(node, Diagnostics._0_declarations_may_not_have_binding_patterns, "using"); + } + } + + if (node.parent.parent.kind !== SyntaxKind.ForInStatement && node.parent.parent.kind !== SyntaxKind.ForOfStatement) { + if (nodeFlags & NodeFlags.Ambient) { + checkAmbientInitializer(node); + } + else if (!node.initializer) { + if (isBindingPattern(node.name) && !isBindingPattern(node.parent)) { + return grammarErrorOnNode(node, Diagnostics.A_destructuring_declaration_must_have_an_initializer); + } + switch (blockScopeKind) { + case NodeFlags.AwaitUsing: + return grammarErrorOnNode(node, Diagnostics._0_declarations_must_be_initialized, "await using"); + case NodeFlags.Using: + return grammarErrorOnNode(node, Diagnostics._0_declarations_must_be_initialized, "using"); + case NodeFlags.Const: + return grammarErrorOnNode(node, Diagnostics._0_declarations_must_be_initialized, "const"); + } + } + } + + if (node.exclamationToken && (node.parent.parent.kind !== SyntaxKind.VariableStatement || !node.type || node.initializer || nodeFlags & NodeFlags.Ambient)) { + const message = node.initializer + ? Diagnostics.Declarations_with_initializers_cannot_also_have_definite_assignment_assertions + : !node.type + ? Diagnostics.Declarations_with_definite_assignment_assertions_must_also_have_type_annotations + : Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context; + return grammarErrorOnNode(node.exclamationToken, message); + } + + if ( + (moduleKind < ModuleKind.ES2015 || getSourceFileOfNode(node).impliedNodeFormat === ModuleKind.CommonJS) && moduleKind !== ModuleKind.System && + !(node.parent.parent.flags & NodeFlags.Ambient) && hasSyntacticModifier(node.parent.parent, ModifierFlags.Export) + ) { + checkESModuleMarker(node.name); + } + + // 1. LexicalDeclaration : LetOrConst BindingList ; + // It is a Syntax Error if the BoundNames of BindingList contains "let". + // 2. ForDeclaration: ForDeclaration : LetOrConst ForBinding + // It is a Syntax Error if the BoundNames of ForDeclaration contains "let". + + // It is a SyntaxError if a VariableDeclaration or VariableDeclarationNoIn occurs within strict code + // and its Identifier is eval or arguments + return !!blockScopeKind && checkGrammarNameInLetOrConstDeclarations(node.name); + } + + function checkESModuleMarker(name: Identifier | BindingPattern): boolean { + if (name.kind === SyntaxKind.Identifier) { + if (idText(name) === "__esModule") { + return grammarErrorOnNodeSkippedOn("noEmit", name, Diagnostics.Identifier_expected_esModule_is_reserved_as_an_exported_marker_when_transforming_ECMAScript_modules); + } + } + else { + const elements = name.elements; + for (const element of elements) { + if (!isOmittedExpression(element)) { + return checkESModuleMarker(element.name); + } + } + } + return false; + } + + function checkGrammarNameInLetOrConstDeclarations(name: Identifier | BindingPattern): boolean { + if (name.kind === SyntaxKind.Identifier) { + if (name.escapedText === "let") { + return grammarErrorOnNode(name, Diagnostics.let_is_not_allowed_to_be_used_as_a_name_in_let_or_const_declarations); + } + } + else { + const elements = name.elements; + for (const element of elements) { + if (!isOmittedExpression(element)) { + checkGrammarNameInLetOrConstDeclarations(element.name); + } + } + } + return false; + } + + function checkGrammarVariableDeclarationList(declarationList: VariableDeclarationList): boolean { + const declarations = declarationList.declarations; + if (checkGrammarForDisallowedTrailingComma(declarationList.declarations)) { + return true; + } + + if (!declarationList.declarations.length) { + return grammarErrorAtPos(declarationList, declarations.pos, declarations.end - declarations.pos, Diagnostics.Variable_declaration_list_cannot_be_empty); + } + + const blockScopeFlags = declarationList.flags & NodeFlags.BlockScoped; + if ((blockScopeFlags === NodeFlags.Using || blockScopeFlags === NodeFlags.AwaitUsing) && isForInStatement(declarationList.parent)) { + return grammarErrorOnNode( + declarationList, + blockScopeFlags === NodeFlags.Using ? + Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_a_using_declaration : + Diagnostics.The_left_hand_side_of_a_for_in_statement_cannot_be_an_await_using_declaration, + ); + } + + if (blockScopeFlags === NodeFlags.AwaitUsing) { + return checkAwaitGrammar(declarationList); + } + + return false; + } + + function allowLetAndConstDeclarations(parent: Node): boolean { + switch (parent.kind) { + case SyntaxKind.IfStatement: + case SyntaxKind.DoStatement: + case SyntaxKind.WhileStatement: + case SyntaxKind.WithStatement: + case SyntaxKind.ForStatement: + case SyntaxKind.ForInStatement: + case SyntaxKind.ForOfStatement: + return false; + case SyntaxKind.LabeledStatement: + return allowLetAndConstDeclarations(parent.parent); + } + + return true; + } + + function checkGrammarForDisallowedBlockScopedVariableStatement(node: VariableStatement) { + if (!allowLetAndConstDeclarations(node.parent)) { + const blockScopeKind = getCombinedNodeFlagsCached(node.declarationList) & NodeFlags.BlockScoped; + if (blockScopeKind) { + const keyword = blockScopeKind === NodeFlags.Let ? "let" : + blockScopeKind === NodeFlags.Const ? "const" : + blockScopeKind === NodeFlags.Using ? "using" : + blockScopeKind === NodeFlags.AwaitUsing ? "await using" : + Debug.fail("Unknown BlockScope flag"); + return grammarErrorOnNode(node, Diagnostics._0_declarations_can_only_be_declared_inside_a_block, keyword); + } + } + } + + function checkGrammarMetaProperty(node: MetaProperty) { + const escapedText = node.name.escapedText; + switch (node.keywordToken) { + case SyntaxKind.NewKeyword: + if (escapedText !== "target") { + return grammarErrorOnNode(node.name, Diagnostics._0_is_not_a_valid_meta_property_for_keyword_1_Did_you_mean_2, unescapeLeadingUnderscores(node.name.escapedText), tokenToString(node.keywordToken), "target"); + } + break; + case SyntaxKind.ImportKeyword: + if (escapedText !== "meta") { + return grammarErrorOnNode(node.name, Diagnostics._0_is_not_a_valid_meta_property_for_keyword_1_Did_you_mean_2, unescapeLeadingUnderscores(node.name.escapedText), tokenToString(node.keywordToken), "meta"); + } + break; + } + } + + function hasParseDiagnostics(sourceFile: SourceFile): boolean { + return sourceFile.parseDiagnostics.length > 0; + } + + function grammarErrorOnFirstToken(node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + const span = getSpanOfTokenAtPosition(sourceFile, node.pos); + diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, message, ...args)); + return true; + } + return false; + } + + function grammarErrorAtPos(nodeForSourceFile: Node, start: number, length: number, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(nodeForSourceFile); + if (!hasParseDiagnostics(sourceFile)) { + diagnostics.add(createFileDiagnostic(sourceFile, start, length, message, ...args)); + return true; + } + return false; + } + + function grammarErrorOnNodeSkippedOn(key: keyof CompilerOptions, node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + errorSkippedOn(key, node, message, ...args); + return true; + } + return false; + } + + function grammarErrorOnNode(node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + diagnostics.add(createDiagnosticForNode(node, message, ...args)); + return true; + } + return false; + } + + function checkGrammarConstructorTypeParameters(node: ConstructorDeclaration) { + const jsdocTypeParameters = isInJSFile(node) ? getJSDocTypeParameterDeclarations(node) : undefined; + const range = node.typeParameters || jsdocTypeParameters && firstOrUndefined(jsdocTypeParameters); + if (range) { + const pos = range.pos === range.end ? range.pos : skipTrivia(getSourceFileOfNode(node).text, range.pos); + return grammarErrorAtPos(node, pos, range.end - pos, Diagnostics.Type_parameters_cannot_appear_on_a_constructor_declaration); + } + } + + function checkGrammarConstructorTypeAnnotation(node: ConstructorDeclaration) { + const type = node.type || getEffectiveReturnTypeNode(node); + if (type) { + return grammarErrorOnNode(type, Diagnostics.Type_annotation_cannot_appear_on_a_constructor_declaration); + } + } + + function checkGrammarProperty(node: PropertyDeclaration | PropertySignature) { + if (isComputedPropertyName(node.name) && isBinaryExpression(node.name.expression) && node.name.expression.operatorToken.kind === SyntaxKind.InKeyword) { + return grammarErrorOnNode(node.parent.members[0], Diagnostics.A_mapped_type_may_not_declare_properties_or_methods); + } + if (isClassLike(node.parent)) { + if (isStringLiteral(node.name) && node.name.text === "constructor") { + return grammarErrorOnNode(node.name, Diagnostics.Classes_may_not_have_a_field_named_constructor); + } + if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_class_property_declaration_must_have_a_simple_literal_type_or_a_unique_symbol_type)) { + return true; + } + if (languageVersion < ScriptTarget.ES2015 && isPrivateIdentifier(node.name)) { + return grammarErrorOnNode(node.name, Diagnostics.Private_identifiers_are_only_available_when_targeting_ECMAScript_2015_and_higher); + } + if (languageVersion < ScriptTarget.ES2015 && isAutoAccessorPropertyDeclaration(node)) { + return grammarErrorOnNode(node.name, Diagnostics.Properties_with_the_accessor_modifier_are_only_available_when_targeting_ECMAScript_2015_and_higher); + } + if (isAutoAccessorPropertyDeclaration(node) && checkGrammarForInvalidQuestionMark(node.questionToken, Diagnostics.An_accessor_property_cannot_be_declared_optional)) { + return true; + } + } + else if (node.parent.kind === SyntaxKind.InterfaceDeclaration) { + if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_an_interface_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type)) { + return true; + } + + // Interfaces cannot contain property declarations + Debug.assertNode(node, isPropertySignature); + if (node.initializer) { + return grammarErrorOnNode(node.initializer, Diagnostics.An_interface_property_cannot_have_an_initializer); + } + } + else if (isTypeLiteralNode(node.parent)) { + if (checkGrammarForInvalidDynamicName(node.name, Diagnostics.A_computed_property_name_in_a_type_literal_must_refer_to_an_expression_whose_type_is_a_literal_type_or_a_unique_symbol_type)) { + return true; + } + // Type literals cannot contain property declarations + Debug.assertNode(node, isPropertySignature); + if (node.initializer) { + return grammarErrorOnNode(node.initializer, Diagnostics.A_type_literal_property_cannot_have_an_initializer); + } + } + + if (node.flags & NodeFlags.Ambient) { + checkAmbientInitializer(node); + } + + if ( + isPropertyDeclaration(node) && node.exclamationToken && (!isClassLike(node.parent) || !node.type || node.initializer || + node.flags & NodeFlags.Ambient || isStatic(node) || hasAbstractModifier(node)) + ) { + const message = node.initializer + ? Diagnostics.Declarations_with_initializers_cannot_also_have_definite_assignment_assertions + : !node.type + ? Diagnostics.Declarations_with_definite_assignment_assertions_must_also_have_type_annotations + : Diagnostics.A_definite_assignment_assertion_is_not_permitted_in_this_context; + return grammarErrorOnNode(node.exclamationToken, message); + } + } + + function checkGrammarTopLevelElementForRequiredDeclareModifier(node: Node): boolean { + // A declare modifier is required for any top level .d.ts declaration except export=, export default, export as namespace + // interfaces and imports categories: + // + // DeclarationElement: + // ExportAssignment + // export_opt InterfaceDeclaration + // export_opt TypeAliasDeclaration + // export_opt ImportDeclaration + // export_opt ExternalImportDeclaration + // export_opt AmbientDeclaration + // + // TODO: The spec needs to be amended to reflect this grammar. + if ( + node.kind === SyntaxKind.InterfaceDeclaration || + node.kind === SyntaxKind.TypeAliasDeclaration || + node.kind === SyntaxKind.ImportDeclaration || + node.kind === SyntaxKind.ImportEqualsDeclaration || + node.kind === SyntaxKind.ExportDeclaration || + node.kind === SyntaxKind.ExportAssignment || + node.kind === SyntaxKind.NamespaceExportDeclaration || + hasSyntacticModifier(node, ModifierFlags.Ambient | ModifierFlags.Export | ModifierFlags.Default) + ) { + return false; + } + + return grammarErrorOnFirstToken(node, Diagnostics.Top_level_declarations_in_d_ts_files_must_start_with_either_a_declare_or_export_modifier); + } + + function checkGrammarTopLevelElementsForRequiredDeclareModifier(file: SourceFile): boolean { + for (const decl of file.statements) { + if (isDeclaration(decl) || decl.kind === SyntaxKind.VariableStatement) { + if (checkGrammarTopLevelElementForRequiredDeclareModifier(decl)) { + return true; + } + } + } + return false; + } + + function checkGrammarSourceFile(node: SourceFile): boolean { + return !!(node.flags & NodeFlags.Ambient) && checkGrammarTopLevelElementsForRequiredDeclareModifier(node); + } + + function checkGrammarStatementInAmbientContext(node: Node): boolean { + if (node.flags & NodeFlags.Ambient) { + // Find containing block which is either Block, ModuleBlock, SourceFile + const links = getNodeLinks(node); + if (!links.hasReportedStatementInAmbientContext && (isFunctionLike(node.parent) || isAccessor(node.parent))) { + return getNodeLinks(node).hasReportedStatementInAmbientContext = grammarErrorOnFirstToken(node, Diagnostics.An_implementation_cannot_be_declared_in_ambient_contexts); + } + + // We are either parented by another statement, or some sort of block. + // If we're in a block, we only want to really report an error once + // to prevent noisiness. So use a bit on the block to indicate if + // this has already been reported, and don't report if it has. + // + if (node.parent.kind === SyntaxKind.Block || node.parent.kind === SyntaxKind.ModuleBlock || node.parent.kind === SyntaxKind.SourceFile) { + const links = getNodeLinks(node.parent); + // Check if the containing block ever report this error + if (!links.hasReportedStatementInAmbientContext) { + return links.hasReportedStatementInAmbientContext = grammarErrorOnFirstToken(node, Diagnostics.Statements_are_not_allowed_in_ambient_contexts); + } + } + else { + // We must be parented by a statement. If so, there's no need + // to report the error as our parent will have already done it. + // Debug.assert(isStatement(node.parent)); + } + } + return false; + } + + function checkGrammarNumericLiteral(node: NumericLiteral) { + // Realism (size) checking + // We should test against `getTextOfNode(node)` rather than `node.text`, because `node.text` for large numeric literals can contain "." + // e.g. `node.text` for numeric literal `1100000000000000000000` is `1.1e21`. + const isFractional = getTextOfNode(node).includes("."); + const isScientific = node.numericLiteralFlags & TokenFlags.Scientific; + + // Scientific notation (e.g. 2e54 and 1e00000000010) can't be converted to bigint + // Fractional numbers (e.g. 9000000000000000.001) are inherently imprecise anyway + if (isFractional || isScientific) { + return; + } + + // Here `node` is guaranteed to be a numeric literal representing an integer. + // We need to judge whether the integer `node` represents is <= 2 ** 53 - 1, which can be accomplished by comparing to `value` defined below because: + // 1) when `node` represents an integer <= 2 ** 53 - 1, `node.text` is its exact string representation and thus `value` precisely represents the integer. + // 2) otherwise, although `node.text` may be imprecise string representation, its mathematical value and consequently `value` cannot be less than 2 ** 53, + // thus the result of the predicate won't be affected. + const value = +node.text; + if (value <= 2 ** 53 - 1) { + return; + } + + addErrorOrSuggestion(/*isError*/ false, createDiagnosticForNode(node, Diagnostics.Numeric_literals_with_absolute_values_equal_to_2_53_or_greater_are_too_large_to_be_represented_accurately_as_integers)); + } + + function checkGrammarBigIntLiteral(node: BigIntLiteral): boolean { + const literalType = isLiteralTypeNode(node.parent) || + isPrefixUnaryExpression(node.parent) && isLiteralTypeNode(node.parent.parent); + if (!literalType) { + if (languageVersion < ScriptTarget.ES2020) { + if (grammarErrorOnNode(node, Diagnostics.BigInt_literals_are_not_available_when_targeting_lower_than_ES2020)) { + return true; + } + } + } + return false; + } + + function grammarErrorAfterFirstToken(node: Node, message: DiagnosticMessage, ...args: DiagnosticArguments): boolean { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + const span = getSpanOfTokenAtPosition(sourceFile, node.pos); + diagnostics.add(createFileDiagnostic(sourceFile, textSpanEnd(span), /*length*/ 0, message, ...args)); + return true; + } + return false; + } + + function getAmbientModules(): Symbol[] { + if (!ambientModulesCache) { + ambientModulesCache = []; + globals.forEach((global, sym) => { + // No need to `unescapeLeadingUnderscores`, an escaped symbol is never an ambient module. + if (ambientModuleSymbolRegex.test(sym as string)) { + ambientModulesCache!.push(global); + } + }); + } + return ambientModulesCache; + } + + function checkGrammarImportClause(node: ImportClause): boolean { + if (node.isTypeOnly && node.name && node.namedBindings) { + return grammarErrorOnNode(node, Diagnostics.A_type_only_import_can_specify_a_default_import_or_named_bindings_but_not_both); + } + if (node.isTypeOnly && node.namedBindings?.kind === SyntaxKind.NamedImports) { + return checkGrammarNamedImportsOrExports(node.namedBindings); + } + return false; + } + + function checkGrammarNamedImportsOrExports(namedBindings: NamedImportsOrExports): boolean { + return !!forEach(namedBindings.elements, specifier => { + if (specifier.isTypeOnly) { + return grammarErrorOnFirstToken( + specifier, + specifier.kind === SyntaxKind.ImportSpecifier + ? Diagnostics.The_type_modifier_cannot_be_used_on_a_named_import_when_import_type_is_used_on_its_import_statement + : Diagnostics.The_type_modifier_cannot_be_used_on_a_named_export_when_export_type_is_used_on_its_export_statement, + ); + } + }); + } + + function checkGrammarImportCallExpression(node: ImportCall): boolean { + if (compilerOptions.verbatimModuleSyntax && moduleKind === ModuleKind.CommonJS) { + return grammarErrorOnNode(node, Diagnostics.ESM_syntax_is_not_allowed_in_a_CommonJS_module_when_verbatimModuleSyntax_is_enabled); + } + + if (moduleKind === ModuleKind.ES2015) { + return grammarErrorOnNode(node, Diagnostics.Dynamic_imports_are_only_supported_when_the_module_flag_is_set_to_es2020_es2022_esnext_commonjs_amd_system_umd_node16_or_nodenext); + } + + if (node.typeArguments) { + return grammarErrorOnNode(node, Diagnostics.This_use_of_import_is_invalid_import_calls_can_be_written_but_they_must_have_parentheses_and_cannot_have_type_arguments); + } + + const nodeArguments = node.arguments; + if (moduleKind !== ModuleKind.ESNext && moduleKind !== ModuleKind.NodeNext && moduleKind !== ModuleKind.Node16) { + // We are allowed trailing comma after proposal-import-assertions. + checkGrammarForDisallowedTrailingComma(nodeArguments); + + if (nodeArguments.length > 1) { + const importAttributesArgument = nodeArguments[1]; + return grammarErrorOnNode(importAttributesArgument, Diagnostics.Dynamic_imports_only_support_a_second_argument_when_the_module_option_is_set_to_esnext_node16_or_nodenext); + } + } + + if (nodeArguments.length === 0 || nodeArguments.length > 2) { + return grammarErrorOnNode(node, Diagnostics.Dynamic_imports_can_only_accept_a_module_specifier_and_an_optional_set_of_attributes_as_arguments); + } + + // see: parseArgumentOrArrayLiteralElement...we use this function which parse arguments of callExpression to parse specifier for dynamic import. + // parseArgumentOrArrayLiteralElement allows spread element to be in an argument list which is not allowed as specifier in dynamic import. + const spreadElement = find(nodeArguments, isSpreadElement); + if (spreadElement) { + return grammarErrorOnNode(spreadElement, Diagnostics.Argument_of_dynamic_import_cannot_be_spread_element); + } + return false; + } + + function findMatchingTypeReferenceOrTypeAliasReference(source: Type, unionTarget: UnionOrIntersectionType) { + const sourceObjectFlags = getObjectFlags(source); + if (sourceObjectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous) && unionTarget.flags & TypeFlags.Union) { + return find(unionTarget.types, target => { + if (target.flags & TypeFlags.Object) { + const overlapObjFlags = sourceObjectFlags & getObjectFlags(target); + if (overlapObjFlags & ObjectFlags.Reference) { + return (source as TypeReference).target === (target as TypeReference).target; + } + if (overlapObjFlags & ObjectFlags.Anonymous) { + return !!(source as AnonymousType).aliasSymbol && (source as AnonymousType).aliasSymbol === (target as AnonymousType).aliasSymbol; + } + } + return false; + }); + } + } + + function findBestTypeForObjectLiteral(source: Type, unionTarget: UnionOrIntersectionType) { + if (getObjectFlags(source) & ObjectFlags.ObjectLiteral && someType(unionTarget, isArrayLikeType)) { + return find(unionTarget.types, t => !isArrayLikeType(t)); + } + } + + function findBestTypeForInvokable(source: Type, unionTarget: UnionOrIntersectionType) { + let signatureKind = SignatureKind.Call; + const hasSignatures = getSignaturesOfType(source, signatureKind).length > 0 || + (signatureKind = SignatureKind.Construct, getSignaturesOfType(source, signatureKind).length > 0); + if (hasSignatures) { + return find(unionTarget.types, t => getSignaturesOfType(t, signatureKind).length > 0); + } + } + + function findMostOverlappyType(source: Type, unionTarget: UnionOrIntersectionType) { + let bestMatch: Type | undefined; + if (!(source.flags & (TypeFlags.Primitive | TypeFlags.InstantiablePrimitive))) { + let matchingCount = 0; + for (const target of unionTarget.types) { + if (!(target.flags & (TypeFlags.Primitive | TypeFlags.InstantiablePrimitive))) { + const overlap = getIntersectionType([getIndexType(source), getIndexType(target)]); + if (overlap.flags & TypeFlags.Index) { + // perfect overlap of keys + return target; + } + else if (isUnitType(overlap) || overlap.flags & TypeFlags.Union) { + // We only want to account for literal types otherwise. + // If we have a union of index types, it seems likely that we + // needed to elaborate between two generic mapped types anyway. + const len = overlap.flags & TypeFlags.Union ? countWhere((overlap as UnionType).types, isUnitType) : 1; + if (len >= matchingCount) { + bestMatch = target; + matchingCount = len; + } + } + } + } + } + return bestMatch; + } + + function filterPrimitivesIfContainsNonPrimitive(type: UnionType) { + if (maybeTypeOfKind(type, TypeFlags.NonPrimitive)) { + const result = filterType(type, t => !(t.flags & TypeFlags.Primitive)); + if (!(result.flags & TypeFlags.Never)) { + return result; + } + } + return type; + } + + // Keep this up-to-date with the same logic within `getApparentTypeOfContextualType`, since they should behave similarly + function findMatchingDiscriminantType(source: Type, target: Type, isRelatedTo: (source: Type, target: Type) => Ternary) { + if (target.flags & TypeFlags.Union && source.flags & (TypeFlags.Intersection | TypeFlags.Object)) { + const match = getMatchingUnionConstituentForType(target as UnionType, source); + if (match) { + return match; + } + const sourceProperties = getPropertiesOfType(source); + if (sourceProperties) { + const sourcePropertiesFiltered = findDiscriminantProperties(sourceProperties, target); + if (sourcePropertiesFiltered) { + const discriminated = discriminateTypeByDiscriminableItems(target as UnionType, map(sourcePropertiesFiltered, p => ([() => getTypeOfSymbol(p), p.escapedName] as [() => Type, __String])), isRelatedTo); + if (discriminated !== target) { + return discriminated; + } + } + } + } + return undefined; + } + + function getEffectivePropertyNameForPropertyNameNode(node: PropertyName) { + const name = getPropertyNameForPropertyNameNode(node); + return name ? name : + isComputedPropertyName(node) ? tryGetNameFromType(getTypeOfExpression(node.expression)) : undefined; + } + + function getCombinedModifierFlagsCached(node: Declaration) { + // we hold onto the last node and result to speed up repeated lookups against the same node. + if (lastGetCombinedModifierFlagsNode === node) { + return lastGetCombinedModifierFlagsResult; + } + + lastGetCombinedModifierFlagsNode = node; + lastGetCombinedModifierFlagsResult = getCombinedModifierFlags(node); + return lastGetCombinedModifierFlagsResult; + } + + function getCombinedNodeFlagsCached(node: Node) { + // we hold onto the last node and result to speed up repeated lookups against the same node. + if (lastGetCombinedNodeFlagsNode === node) { + return lastGetCombinedNodeFlagsResult; + } + lastGetCombinedNodeFlagsNode = node; + lastGetCombinedNodeFlagsResult = getCombinedNodeFlags(node); + return lastGetCombinedNodeFlagsResult; + } + + function isVarConstLike(node: VariableDeclaration | VariableDeclarationList) { + const blockScopeKind = getCombinedNodeFlagsCached(node) & NodeFlags.BlockScoped; + return blockScopeKind === NodeFlags.Const || + blockScopeKind === NodeFlags.Using || + blockScopeKind === NodeFlags.AwaitUsing; + } + + function getJSXRuntimeImportSpecifier(file: SourceFile | undefined, specifierText: string) { + // Synthesized JSX import is either first or after tslib + const jsxImportIndex = compilerOptions.importHelpers ? 1 : 0; + const specifier = file?.imports[jsxImportIndex]; + if (specifier) { + Debug.assert(nodeIsSynthesized(specifier) && specifier.text === specifierText, `Expected sourceFile.imports[${jsxImportIndex}] to be the synthesized JSX runtime import`); + } + return specifier; + } + + function getImportHelpersImportSpecifier(file: SourceFile) { + Debug.assert(compilerOptions.importHelpers, "Expected importHelpers to be enabled"); + const specifier = file.imports[0]; + Debug.assert(specifier && nodeIsSynthesized(specifier) && specifier.text === "tslib", `Expected sourceFile.imports[0] to be the synthesized tslib import`); + return specifier; + } +} + +function isNotAccessor(declaration: Declaration): boolean { + // Accessors check for their own matching duplicates, and in contexts where they are valid, there are already duplicate identifier checks + return !isAccessor(declaration); +} + +function isNotOverload(declaration: Declaration): boolean { + return (declaration.kind !== SyntaxKind.FunctionDeclaration && declaration.kind !== SyntaxKind.MethodDeclaration) || + !!(declaration as FunctionDeclaration).body; +} + +/** Like 'isDeclarationName', but returns true for LHS of `import { x as y }` or `export { x as y }`. */ +function isDeclarationNameOrImportPropertyName(name: Node): boolean { + switch (name.parent.kind) { + case SyntaxKind.ImportSpecifier: + case SyntaxKind.ExportSpecifier: + return isIdentifier(name) || name.kind === SyntaxKind.StringLiteral; + default: + return isDeclarationName(name); + } +} + +namespace JsxNames { + export const JSX = "JSX" as __String; + export const IntrinsicElements = "IntrinsicElements" as __String; + export const ElementClass = "ElementClass" as __String; + export const ElementAttributesPropertyNameContainer = "ElementAttributesProperty" as __String; // TODO: Deprecate and remove support + export const ElementChildrenAttributeNameContainer = "ElementChildrenAttribute" as __String; + export const Element = "Element" as __String; + export const ElementType = "ElementType" as __String; + export const IntrinsicAttributes = "IntrinsicAttributes" as __String; + export const IntrinsicClassAttributes = "IntrinsicClassAttributes" as __String; + export const LibraryManagedAttributes = "LibraryManagedAttributes" as __String; +} + +function getIterationTypesKeyFromIterationTypeKind(typeKind: IterationTypeKind) { + switch (typeKind) { + case IterationTypeKind.Yield: + return "yieldType"; + case IterationTypeKind.Return: + return "returnType"; + case IterationTypeKind.Next: + return "nextType"; + } +} + +/** @internal */ +export function signatureHasRestParameter(s: Signature) { + return !!(s.flags & SignatureFlags.HasRestParameter); +} + +/** @internal */ +export function signatureHasLiteralTypes(s: Signature) { + return !!(s.flags & SignatureFlags.HasLiteralTypes); +} + +function createBasicNodeBuilderModuleSpecifierResolutionHost(host: TypeCheckerHost): ModuleSpecifierResolutionHost { + return { + getCommonSourceDirectory: !!(host as Program).getCommonSourceDirectory ? () => (host as Program).getCommonSourceDirectory() : () => "", + getCurrentDirectory: () => host.getCurrentDirectory(), + getSymlinkCache: maybeBind(host, host.getSymlinkCache), + getPackageJsonInfoCache: () => host.getPackageJsonInfoCache?.(), + useCaseSensitiveFileNames: maybeBind(host, host.useCaseSensitiveFileNames), + redirectTargetsMap: host.redirectTargetsMap, + getProjectReferenceRedirect: fileName => host.getProjectReferenceRedirect(fileName), + isSourceOfProjectReferenceRedirect: fileName => host.isSourceOfProjectReferenceRedirect(fileName), + fileExists: fileName => host.fileExists(fileName), + getFileIncludeReasons: () => host.getFileIncludeReasons(), + readFile: host.readFile ? (fileName => host.readFile!(fileName)) : undefined, + }; +} + +interface NodeBuilderContext { + enclosingDeclaration: Node | undefined; + /** + * `enclosingFile` is generated from the initial `enclosingDeclaration` and + * is used to ensure text ranges for generated nodes are not set based on nodes from outside + * the original input's containing file. Checking the `enclosingDeclaration` at the time of + * `setTextRange` is not sufficient, as the `enclosingDeclaration` is modified by the node builder + * as it decends into some types as a shortcut to making certain scopes visible, and may be modified + * into a declaration in a different file from the original input `enclosingDeclaration`! + */ + enclosingFile: SourceFile | undefined; + flags: NodeBuilderFlags; + tracker: SymbolTrackerImpl; + + // State + encounteredError: boolean; + reportedDiagnostic: boolean; + trackedSymbols: TrackedSymbol[] | undefined; + visitedTypes: Set | undefined; + symbolDepth: Map | undefined; + inferTypeParameters: TypeParameter[] | undefined; + approximateLength: number; + truncating: boolean; + mustCreateTypeParameterSymbolList: boolean; + typeParameterSymbolList: Set | undefined; + mustCreateTypeParametersNamesLookups: boolean; + typeParameterNames: Map | undefined; + typeParameterNamesByText: Set | undefined; + typeParameterNamesByTextNextNameCount: Map | undefined; + usedSymbolNames: Set | undefined; + remappedSymbolNames: Map | undefined; + remappedSymbolReferences: Map | undefined; + reverseMappedStack: ReverseMappedSymbol[] | undefined; + bundled: boolean; + mapper: TypeMapper | undefined; +} + +class SymbolTrackerImpl implements SymbolTracker { + moduleResolverHost: ModuleSpecifierResolutionHost & { getCommonSourceDirectory(): string; } | undefined = undefined; + context: NodeBuilderContext; + + readonly inner: SymbolTracker | undefined = undefined; + readonly canTrackSymbol: boolean; + disableTrackSymbol = false; + + constructor(context: NodeBuilderContext, tracker: SymbolTracker | undefined, moduleResolverHost: ModuleSpecifierResolutionHost & { getCommonSourceDirectory(): string; } | undefined) { + while (tracker instanceof SymbolTrackerImpl) { + tracker = tracker.inner; + } + + this.inner = tracker; + this.moduleResolverHost = moduleResolverHost; + this.context = context; + this.canTrackSymbol = !!this.inner?.trackSymbol; + } + + trackSymbol(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags): boolean { + if (this.inner?.trackSymbol && !this.disableTrackSymbol) { + if (this.inner.trackSymbol(symbol, enclosingDeclaration, meaning)) { + this.onDiagnosticReported(); + return true; + } + // Skip recording type parameters as they dont contribute to late painted statements + if (!(symbol.flags & SymbolFlags.TypeParameter)) (this.context.trackedSymbols ??= []).push([symbol, enclosingDeclaration, meaning]); + } + return false; + } + + reportInaccessibleThisError(): void { + if (this.inner?.reportInaccessibleThisError) { + this.onDiagnosticReported(); + this.inner.reportInaccessibleThisError(); + } + } + + reportPrivateInBaseOfClassExpression(propertyName: string): void { + if (this.inner?.reportPrivateInBaseOfClassExpression) { + this.onDiagnosticReported(); + this.inner.reportPrivateInBaseOfClassExpression(propertyName); + } + } + + reportInaccessibleUniqueSymbolError(): void { + if (this.inner?.reportInaccessibleUniqueSymbolError) { + this.onDiagnosticReported(); + this.inner.reportInaccessibleUniqueSymbolError(); + } + } + + reportCyclicStructureError(): void { + if (this.inner?.reportCyclicStructureError) { + this.onDiagnosticReported(); + this.inner.reportCyclicStructureError(); + } + } + + reportLikelyUnsafeImportRequiredError(specifier: string): void { + if (this.inner?.reportLikelyUnsafeImportRequiredError) { + this.onDiagnosticReported(); + this.inner.reportLikelyUnsafeImportRequiredError(specifier); + } + } + + reportTruncationError(): void { + if (this.inner?.reportTruncationError) { + this.onDiagnosticReported(); + this.inner.reportTruncationError(); + } + } + + reportNonlocalAugmentation(containingFile: SourceFile, parentSymbol: Symbol, augmentingSymbol: Symbol): void { + if (this.inner?.reportNonlocalAugmentation) { + this.onDiagnosticReported(); + this.inner.reportNonlocalAugmentation(containingFile, parentSymbol, augmentingSymbol); + } + } + + reportNonSerializableProperty(propertyName: string): void { + if (this.inner?.reportNonSerializableProperty) { + this.onDiagnosticReported(); + this.inner.reportNonSerializableProperty(propertyName); + } + } + + private onDiagnosticReported() { + this.context.reportedDiagnostic = true; + } + + reportInferenceFallback(node: Node): void { + if (this.inner?.reportInferenceFallback) { + this.inner.reportInferenceFallback(node); + } + } +} +import { + __String, + AccessExpression, + AccessFlags, + AccessorDeclaration, + addRange, + addRelatedInfo, + addSyntheticLeadingComment, + AliasDeclarationNode, + AllAccessorDeclarations, + AmbientModuleDeclaration, + and, + AnonymousType, + AnyImportOrJsDocImport, + AnyImportOrReExport, + append, + appendIfUnique, + ArrayBindingPattern, + arrayFrom, + arrayIsHomogeneous, + ArrayLiteralExpression, + arrayOf, + arraysEqual, + arrayToMultiMap, + ArrayTypeNode, + ArrowFunction, + AsExpression, + AssertionExpression, + AssignmentDeclarationKind, + AssignmentKind, + AssignmentPattern, + AwaitExpression, + BaseType, + BigIntLiteral, + BigIntLiteralType, + BinaryExpression, + BinaryOperator, + BinaryOperatorToken, + binarySearch, + BindableObjectDefinePropertyCall, + BindableStaticNameExpression, + BindingElement, + BindingElementGrandparent, + BindingName, + BindingPattern, + bindSourceFile, + Block, + BooleanLiteral, + BreakOrContinueStatement, + CallChain, + CallExpression, + CallLikeExpression, + CallSignatureDeclaration, + CancellationToken, + canHaveDecorators, + canHaveExportModifier, + canHaveFlowNode, + canHaveIllegalDecorators, + canHaveIllegalModifiers, + canHaveJSDoc, + canHaveLocals, + canHaveModifiers, + canHaveSymbol, + canIncludeBindAndCheckDiagnostics, + canUsePropertyAccess, + cartesianProduct, + CaseBlock, + CaseClause, + CaseOrDefaultClause, + cast, + chainDiagnosticMessages, + CharacterCodes, + CheckFlags, + ClassDeclaration, + ClassElement, + classElementOrClassElementParameterIsDecorated, + ClassExpression, + ClassLikeDeclaration, + classOrConstructorParameterIsDecorated, + ClassStaticBlockDeclaration, + clear, + combinePaths, + compareDiagnostics, + comparePaths, + compareValues, + Comparison, + CompilerOptions, + ComputedPropertyName, + concatenate, + concatenateDiagnosticMessageChains, + ConditionalExpression, + ConditionalRoot, + ConditionalType, + ConditionalTypeNode, + ConstructorDeclaration, + ConstructorTypeNode, + ConstructSignatureDeclaration, + contains, + containsParseError, + ContextFlags, + copyEntries, + countWhere, + createBinaryExpressionTrampoline, + createCompilerDiagnostic, + createDetachedDiagnostic, + createDiagnosticCollection, + createDiagnosticForFileFromMessageChain, + createDiagnosticForNode, + createDiagnosticForNodeArray, + createDiagnosticForNodeArrayFromMessageChain, + createDiagnosticForNodeFromMessageChain, + createDiagnosticMessageChainFromDiagnostic, + createEmptyExports, + createEvaluator, + createFileDiagnostic, + createFlowNode, + createGetSymbolWalker, + createModeAwareCacheKey, + createModuleNotFoundChain, + createMultiMap, + createNameResolver, + createPrinterWithDefaults, + createPrinterWithRemoveComments, + createPrinterWithRemoveCommentsNeverAsciiEscape, + createPrinterWithRemoveCommentsOmitTrailingSemicolon, + createPropertyNameNodeForIdentifierOrLiteral, + createScanner, + createSymbolTable, + createSyntacticTypeNodeBuilder, + createTextWriter, + Debug, + Declaration, + DeclarationName, + declarationNameToString, + DeclarationStatement, + DeclarationWithTypeParameterChildren, + DeclarationWithTypeParameters, + Decorator, + deduplicate, + DefaultClause, + defaultMaximumTruncationLength, + DeferredTypeReference, + DeleteExpression, + Diagnostic, + DiagnosticAndArguments, + DiagnosticArguments, + DiagnosticCategory, + DiagnosticMessage, + DiagnosticMessageChain, + DiagnosticRelatedInformation, + Diagnostics, + DiagnosticWithLocation, + DoStatement, + DynamicNamedDeclaration, + ElementAccessChain, + ElementAccessExpression, + ElementFlags, + EmitFlags, + EmitHint, + emitModuleKindIsNonNodeESM, + EmitResolver, + EmitTextWriter, + emptyArray, + endsWith, + EntityName, + EntityNameExpression, + EntityNameOrEntityNameExpression, + entityNameToString, + EnumDeclaration, + EnumMember, + EnumType, + equateValues, + escapeLeadingUnderscores, + escapeString, + EvaluatorResult, + evaluatorResult, + every, + EvolvingArrayType, + ExclamationToken, + ExportAssignment, + exportAssignmentIsAlias, + ExportDeclaration, + ExportSpecifier, + Expression, + expressionResultIsUnused, + ExpressionStatement, + ExpressionWithTypeArguments, + Extension, + ExternalEmitHelpers, + externalHelpersModuleNameText, + factory, + fileExtensionIs, + fileExtensionIsOneOf, + filter, + find, + findAncestor, + findBestPatternMatch, + findConstructorDeclaration, + findIndex, + findLast, + findLastIndex, + findUseStrictPrologue, + first, + firstDefined, + firstIterator, + firstOrUndefined, + firstOrUndefinedIterator, + flatMap, + flatten, + FlowArrayMutation, + FlowAssignment, + FlowCall, + FlowCondition, + FlowFlags, + FlowLabel, + FlowNode, + FlowReduceLabel, + FlowStart, + FlowSwitchClause, + FlowSwitchClauseData, + FlowType, + forEach, + forEachChild, + forEachChildRecursively, + forEachEnclosingBlockScopeContainer, + forEachEntry, + forEachKey, + forEachReturnStatement, + forEachYieldExpression, + ForInOrOfStatement, + ForInStatement, + formatMessage, + ForOfStatement, + ForStatement, + FreshableIntrinsicType, + FreshableType, + FreshObjectLiteralType, + FunctionDeclaration, + FunctionExpression, + FunctionFlags, + FunctionLikeDeclaration, + FunctionOrConstructorTypeNode, + FunctionTypeNode, + GenericType, + GetAccessorDeclaration, + getAliasDeclarationFromName, + getAllJSDocTags, + getAllowSyntheticDefaultImports, + getAncestor, + getAssignedExpandoInitializer, + getAssignmentDeclarationKind, + getAssignmentDeclarationPropertyAccessKind, + getAssignmentTargetKind, + getCanonicalDiagnostic, + getCheckFlags, + getClassExtendsHeritageElement, + getClassLikeDeclarationOfSymbol, + getCombinedLocalAndExportSymbolFlags, + getCombinedModifierFlags, + getCombinedNodeFlags, + getContainingClass, + getContainingClassExcludingClassDecorators, + getContainingClassStaticBlock, + getContainingFunction, + getContainingFunctionOrClassStaticBlock, + getDeclarationModifierFlagsFromSymbol, + getDeclarationOfKind, + getDeclarationsOfKind, + getDeclaredExpandoInitializer, + getDecorators, + getDirectoryPath, + getEffectiveBaseTypeNode, + getEffectiveConstraintOfTypeParameter, + getEffectiveContainerForJSDocTemplateTag, + getEffectiveImplementsTypeNodes, + getEffectiveInitializer, + getEffectiveJSDocHost, + getEffectiveModifierFlags, + getEffectiveReturnTypeNode, + getEffectiveSetAccessorTypeAnnotationNode, + getEffectiveTypeAnnotationNode, + getEffectiveTypeParameterDeclarations, + getElementOrPropertyAccessName, + getEmitDeclarations, + getEmitFlags, + getEmitModuleKind, + getEmitModuleResolutionKind, + getEmitScriptTarget, + getEmitStandardClassFields, + getEnclosingBlockScopeContainer, + getEnclosingContainer, + getEntityNameFromTypeNode, + getErrorSpanForNode, + getEscapedTextOfIdentifierOrLiteral, + getEscapedTextOfJsxAttributeName, + getEscapedTextOfJsxNamespacedName, + getESModuleInterop, + getExpandoInitializer, + getExportAssignmentExpression, + getExternalModuleImportEqualsDeclarationExpression, + getExternalModuleName, + getExternalModuleRequireArgument, + getFirstConstructorWithBody, + getFirstIdentifier, + getFunctionFlags, + getHostSignatureFromJSDoc, + getIdentifierGeneratedImportReference, + getIdentifierTypeArguments, + getImmediatelyInvokedFunctionExpression, + getInitializerOfBinaryExpression, + getInterfaceBaseTypeNodes, + getInvokedExpression, + getIsolatedModules, + getJSDocClassTag, + getJSDocDeprecatedTag, + getJSDocEnumTag, + getJSDocHost, + getJSDocOverloadTags, + getJSDocParameterTags, + getJSDocRoot, + getJSDocSatisfiesExpressionType, + getJSDocTags, + getJSDocThisTag, + getJSDocType, + getJSDocTypeAssertionType, + getJSDocTypeParameterDeclarations, + getJSDocTypeTag, + getJSXImplicitImportBase, + getJSXRuntimeImport, + getJSXTransformEnabled, + getLeftmostAccessExpression, + getLineAndCharacterOfPosition, + getMembersOfDeclaration, + getModifiers, + getModuleInstanceState, + getNameFromImportAttribute, + getNameFromIndexInfo, + getNameOfDeclaration, + getNameOfExpando, + getNamespaceDeclarationNode, + getNewTargetContainer, + getNonAugmentationDeclaration, + getNormalizedAbsolutePath, + getObjectFlags, + getOriginalNode, + getOrUpdate, + getParameterSymbolFromJSDoc, + getParseTreeNode, + getPropertyAssignmentAliasLikeExpression, + getPropertyNameForPropertyNameNode, + getPropertyNameFromType, + getResolutionDiagnostic, + getResolutionModeOverride, + getResolveJsonModule, + getRestParameterElementType, + getRootDeclaration, + getScriptTargetFeatures, + getSelectedEffectiveModifierFlags, + getSemanticJsxChildren, + getSetAccessorValueParameter, + getSingleVariableOfVariableStatement, + getSourceFileOfModule, + getSourceFileOfNode, + getSpanOfTokenAtPosition, + getSpellingSuggestion, + getStrictOptionValue, + getSuperContainer, + getSymbolNameForPrivateIdentifier, + getTextOfIdentifierOrLiteral, + getTextOfJSDocComment, + getTextOfJsxAttributeName, + getTextOfNode, + getTextOfPropertyName, + getThisContainer, + getThisParameter, + getTrailingSemicolonDeferringWriter, + getTypeParameterFromJsDoc, + getUseDefineForClassFields, + group, + hasAbstractModifier, + hasAccessorModifier, + hasAmbientModifier, + hasContextSensitiveParameters, + HasDecorators, + hasDecorators, + hasDynamicName, + hasEffectiveModifier, + hasEffectiveModifiers, + hasEffectiveReadonlyModifier, + HasExpressionInitializer, + hasExtension, + HasIllegalDecorators, + HasIllegalModifiers, + hasInferredType, + HasInitializer, + hasInitializer, + hasJSDocNodes, + hasJSDocParameterTags, + hasJsonModuleEmitEnabled, + HasLocals, + HasModifiers, + hasOnlyExpressionInitializer, + hasOverrideModifier, + hasPossibleExternalModuleReference, + hasQuestionToken, + hasResolutionModeOverride, + hasRestParameter, + hasScopeMarker, + hasStaticModifier, + hasSyntacticModifier, + hasSyntacticModifiers, + hasType, + HeritageClause, + Identifier, + identifierToKeywordKind, + IdentifierTypePredicate, + idText, + IfStatement, + ImportAttribute, + ImportAttributes, + ImportCall, + ImportClause, + ImportDeclaration, + ImportEqualsDeclaration, + ImportOrExportSpecifier, + ImportSpecifier, + ImportTypeNode, + IndexedAccessType, + IndexedAccessTypeNode, + IndexFlags, + IndexInfo, + IndexKind, + indexOfNode, + IndexSignatureDeclaration, + IndexType, + indicesOf, + InferenceContext, + InferenceFlags, + InferenceInfo, + InferencePriority, + InferTypeNode, + InstanceofExpression, + InstantiableType, + InstantiationExpressionType, + InterfaceDeclaration, + InterfaceType, + InterfaceTypeWithDeclaredMembers, + InternalSymbolName, + IntersectionFlags, + IntersectionType, + IntersectionTypeNode, + intrinsicTagNameToString, + IntrinsicType, + introducesArgumentsExoticObject, + isAccessExpression, + isAccessor, + isAliasableExpression, + isAmbientModule, + isArray, + isArrayBindingPattern, + isArrayLiteralExpression, + isArrowFunction, + isAssertionExpression, + isAssignmentDeclaration, + isAssignmentExpression, + isAssignmentOperator, + isAssignmentPattern, + isAssignmentTarget, + isAutoAccessorPropertyDeclaration, + isAwaitExpression, + isBinaryExpression, + isBindableObjectDefinePropertyCall, + isBindableStaticElementAccessExpression, + isBindableStaticNameExpression, + isBindingElement, + isBindingElementOfBareOrAccessedRequire, + isBindingPattern, + isBlock, + isBlockOrCatchScoped, + isBlockScopedContainerTopLevel, + isBooleanLiteral, + isCallChain, + isCallExpression, + isCallLikeExpression, + isCallLikeOrFunctionLikeExpression, + isCallOrNewExpression, + isCallSignatureDeclaration, + isCatchClause, + isCatchClauseVariableDeclaration, + isCatchClauseVariableDeclarationOrBindingElement, + isCheckJsEnabledForFile, + isClassDeclaration, + isClassElement, + isClassExpression, + isClassInstanceProperty, + isClassLike, + isClassStaticBlockDeclaration, + isCommaSequence, + isCommonJsExportedExpression, + isCommonJsExportPropertyAssignment, + isCompoundAssignment, + isComputedNonLiteralName, + isComputedPropertyName, + isConditionalTypeNode, + isConstAssertion, + isConstructorDeclaration, + isConstructorTypeNode, + isConstructSignatureDeclaration, + isConstTypeReference, + isDeclaration, + isDeclarationFileName, + isDeclarationName, + isDeclarationReadonly, + isDecorator, + isDefaultedExpandoInitializer, + isDeleteTarget, + isDottedName, + isDynamicName, + isEffectiveExternalModule, + isElementAccessExpression, + isEntityName, + isEntityNameExpression, + isEnumConst, + isEnumDeclaration, + isEnumMember, + isExclusivelyTypeOnlyImportOrExport, + isExpandoPropertyDeclaration, + isExportAssignment, + isExportDeclaration, + isExportsIdentifier, + isExportSpecifier, + isExpression, + isExpressionNode, + isExpressionOfOptionalChainRoot, + isExpressionStatement, + isExpressionWithTypeArguments, + isExpressionWithTypeArgumentsInClassExtendsClause, + isExternalModule, + isExternalModuleAugmentation, + isExternalModuleImportEqualsDeclaration, + isExternalModuleIndicator, + isExternalModuleNameRelative, + isExternalModuleReference, + isExternalModuleSymbol, + isExternalOrCommonJsModule, + isForInOrOfStatement, + isForInStatement, + isForOfStatement, + isForStatement, + isFunctionDeclaration, + isFunctionExpression, + isFunctionExpressionOrArrowFunction, + isFunctionLike, + isFunctionLikeDeclaration, + isFunctionLikeOrClassStaticBlockDeclaration, + isFunctionOrModuleBlock, + isFunctionTypeNode, + isGeneratedIdentifier, + isGetAccessor, + isGetAccessorDeclaration, + isGetOrSetAccessorDeclaration, + isGlobalScopeAugmentation, + isGlobalSourceFile, + isHeritageClause, + isIdentifier, + isIdentifierText, + isIdentifierTypePredicate, + isIdentifierTypeReference, + isIfStatement, + isImportAttributes, + isImportCall, + isImportClause, + isImportDeclaration, + isImportEqualsDeclaration, + isImportKeyword, + isImportOrExportSpecifier, + isImportSpecifier, + isImportTypeNode, + isInCompoundLikeAssignment, + isIndexedAccessTypeNode, + isInExpressionContext, + isInfinityOrNaNString, + isInitializedProperty, + isInJSDoc, + isInJSFile, + isInJsonFile, + isInstanceOfExpression, + isInterfaceDeclaration, + isInternalModuleImportEqualsDeclaration, + isInTopLevelContext, + isIntrinsicJsxName, + isInTypeQuery, + isIterationStatement, + isJSDocAllType, + isJSDocAugmentsTag, + isJSDocCallbackTag, + isJSDocConstructSignature, + isJSDocFunctionType, + isJSDocImportTag, + isJSDocIndexSignature, + isJSDocLinkLike, + isJSDocMemberName, + isJSDocNameReference, + isJSDocNode, + isJSDocNonNullableType, + isJSDocNullableType, + isJSDocOptionalParameter, + isJSDocOptionalType, + isJSDocOverloadTag, + isJSDocParameterTag, + isJSDocPropertyLikeTag, + isJSDocPropertyTag, + isJSDocSatisfiesExpression, + isJSDocSatisfiesTag, + isJSDocSignature, + isJSDocTemplateTag, + isJSDocThisTag, + isJSDocTypeAlias, + isJSDocTypeAssertion, + isJSDocTypedefTag, + isJSDocTypeExpression, + isJSDocTypeLiteral, + isJSDocUnknownType, + isJSDocVariadicType, + isJsonSourceFile, + isJsxAttribute, + isJsxAttributeLike, + isJsxAttributes, + isJsxElement, + isJsxNamespacedName, + isJsxOpeningElement, + isJsxOpeningFragment, + isJsxOpeningLikeElement, + isJsxSelfClosingElement, + isJsxSpreadAttribute, + isJSXTagName, + isKnownSymbol, + isLateVisibilityPaintedStatement, + isLeftHandSideExpression, + isLineBreak, + isLiteralComputedPropertyDeclarationName, + isLiteralExpression, + isLiteralExpressionOfObject, + isLiteralImportTypeNode, + isLiteralTypeNode, + isLogicalOrCoalescingBinaryExpression, + isLogicalOrCoalescingBinaryOperator, + isMappedTypeNode, + isMetaProperty, + isMethodDeclaration, + isMethodSignature, + isModifier, + isModuleBlock, + isModuleDeclaration, + isModuleExportsAccessExpression, + isModuleIdentifier, + isModuleOrEnumDeclaration, + isModuleWithStringLiteralName, + isNamedDeclaration, + isNamedEvaluationSource, + isNamedExports, + isNamedTupleMember, + isNamespaceExport, + isNamespaceExportDeclaration, + isNamespaceReexportDeclaration, + isNewExpression, + isNodeDescendantOf, + isNonNullAccess, + isNonNullExpression, + isNumericLiteral, + isNumericLiteralName, + isObjectBindingPattern, + isObjectLiteralElementLike, + isObjectLiteralExpression, + isObjectLiteralMethod, + isObjectLiteralOrClassExpressionMethodOrAccessor, + isOmittedExpression, + isOptionalChain, + isOptionalChainRoot, + isOptionalDeclaration, + isOptionalJSDocPropertyLikeTag, + isOptionalTypeNode, + isOutermostOptionalChain, + isParameter, + isParameterPropertyDeclaration, + isParenthesizedExpression, + isParenthesizedTypeNode, + isPartOfParameterDeclaration, + isPartOfTypeNode, + isPartOfTypeQuery, + isPlainJsFile, + isPrefixUnaryExpression, + isPrivateIdentifier, + isPrivateIdentifierClassElementDeclaration, + isPrivateIdentifierPropertyAccessExpression, + isPropertyAccessEntityNameExpression, + isPropertyAccessExpression, + isPropertyAccessOrQualifiedName, + isPropertyAccessOrQualifiedNameOrImportTypeNode, + isPropertyAssignment, + isPropertyDeclaration, + isPropertyName, + isPropertyNameLiteral, + isPropertySignature, + isPrototypeAccess, + isPrototypePropertyAssignment, + isPushOrUnshiftIdentifier, + isQualifiedName, + isRequireCall, + isRestParameter, + isRestTypeNode, + isRightSideOfAccessExpression, + isRightSideOfInstanceofExpression, + isRightSideOfQualifiedNameOrPropertyAccess, + isRightSideOfQualifiedNameOrPropertyAccessOrJSDocMemberName, + isSameEntityName, + isSatisfiesExpression, + isSetAccessor, + isSetAccessorDeclaration, + isShorthandAmbientModuleSymbol, + isShorthandPropertyAssignment, + isSingleOrDoubleQuote, + isSourceFile, + isSourceFileJS, + isSpreadAssignment, + isSpreadElement, + isStatement, + isStatementWithLocals, + isStatic, + isString, + isStringANonContextualKeyword, + isStringLiteral, + isStringLiteralLike, + isStringOrNumericLiteralLike, + isSuperCall, + isSuperProperty, + isTaggedTemplateExpression, + isTemplateSpan, + isThisContainerOrFunctionBlock, + isThisIdentifier, + isThisInitializedDeclaration, + isThisInitializedObjectBindingExpression, + isThisInTypeQuery, + isThisProperty, + isThisTypeNode, + isThisTypeParameter, + isThisTypePredicate, + isTransientSymbol, + isTupleTypeNode, + isTypeAlias, + isTypeAliasDeclaration, + isTypeDeclaration, + isTypeLiteralNode, + isTypeNode, + isTypeNodeKind, + isTypeOfExpression, + isTypeOnlyImportDeclaration, + isTypeOnlyImportOrExportDeclaration, + isTypeOperatorNode, + isTypeParameterDeclaration, + isTypePredicateNode, + isTypeQueryNode, + isTypeReferenceNode, + isTypeReferenceType, + isTypeUsableAsPropertyName, + isUMDExportSymbol, + isValidBigIntString, + isValidESSymbolDeclaration, + isValidTypeOnlyAliasUseSite, + isValueSignatureDeclaration, + isVariableDeclaration, + isVariableDeclarationInitializedToBareOrAccessedRequire, + isVariableDeclarationInVariableStatement, + isVariableDeclarationList, + isVariableLike, + isVariableLikeOrAccessor, + isVariableStatement, + isWriteAccess, + isWriteOnlyAccess, + IterableOrIteratorType, + IterationTypes, + JSDoc, + JSDocAugmentsTag, + JSDocCallbackTag, + JSDocComment, + JSDocFunctionType, + JSDocImplementsTag, + JSDocImportTag, + JSDocLink, + JSDocLinkCode, + JSDocLinkPlain, + JSDocMemberName, + JSDocNullableType, + JSDocOptionalType, + JSDocOverloadTag, + JSDocParameterTag, + JSDocPrivateTag, + JSDocPropertyLikeTag, + JSDocPropertyTag, + JSDocProtectedTag, + JSDocPublicTag, + JSDocSatisfiesTag, + JSDocSignature, + JSDocTemplateTag, + JSDocThisTag, + JSDocTypeAssertion, + JSDocTypedefTag, + JSDocTypeExpression, + JSDocTypeLiteral, + JSDocTypeReferencingNode, + JSDocTypeTag, + JSDocVariadicType, + JsxAttribute, + JsxAttributeLike, + JsxAttributeName, + JsxAttributes, + JsxAttributeValue, + JsxChild, + JsxClosingElement, + JsxElement, + JsxEmit, + JsxExpression, + JsxFlags, + JsxFragment, + JsxNamespacedName, + JsxOpeningElement, + JsxOpeningFragment, + JsxOpeningLikeElement, + JsxReferenceKind, + JsxSelfClosingElement, + JsxSpreadAttribute, + JsxTagNameExpression, + KeywordTypeNode, + LabeledStatement, + LanguageFeatureMinimumTarget, + last, + lastOrUndefined, + LateBoundBinaryExpressionDeclaration, + LateBoundDeclaration, + LateBoundName, + LateVisibilityPaintedStatement, + LazyNodeCheckFlags, + length, + LiteralExpression, + LiteralType, + LiteralTypeNode, + map, + mapDefined, + MappedSymbol, + MappedType, + MappedTypeNode, + MatchingKeys, + maybeBind, + MemberOverrideStatus, + MetaProperty, + MethodDeclaration, + MethodSignature, + minAndMax, + MinusToken, + Modifier, + ModifierFlags, + modifiersToFlags, + modifierToFlag, + ModuleBlock, + ModuleDeclaration, + ModuleExportName, + moduleExportNameIsDefault, + moduleExportNameTextEscaped, + moduleExportNameTextUnescaped, + ModuleInstanceState, + ModuleKind, + ModuleResolutionKind, + ModuleSpecifierResolutionHost, + Mutable, + NamedDeclaration, + NamedExports, + NamedImportsOrExports, + NamedTupleMember, + NamespaceDeclaration, + NamespaceExport, + NamespaceExportDeclaration, + NamespaceImport, + needsScopeMarker, + NewExpression, + Node, + NodeArray, + NodeBuilderFlags, + nodeCanBeDecorated, + NodeCheckFlags, + NodeFlags, + nodeHasName, + nodeIsMissing, + nodeIsPresent, + nodeIsSynthesized, + NodeLinks, + nodeStartsNewLexicalEnvironment, + NodeWithTypeArguments, + NonNullChain, + NonNullExpression, + not, + noTruncationMaximumTruncationLength, + NumberLiteralType, + NumericLiteral, + objectAllocator, + ObjectBindingPattern, + ObjectFlags, + ObjectFlagsType, + ObjectLiteralElementLike, + ObjectLiteralExpression, + ObjectType, + OptionalChain, + OptionalTypeNode, + or, + orderedRemoveItemAt, + OuterExpressionKinds, + ParameterDeclaration, + parameterIsThisKeyword, + ParameterPropertyDeclaration, + ParenthesizedExpression, + ParenthesizedTypeNode, + parseIsolatedEntityName, + parseNodeFactory, + parsePseudoBigInt, + parseValidBigInt, + Path, + pathIsRelative, + PatternAmbientModule, + PlusToken, + PostfixUnaryExpression, + PrefixUnaryExpression, + PrivateIdentifier, + Program, + PromiseOrAwaitableType, + PropertyAccessChain, + PropertyAccessEntityNameExpression, + PropertyAccessExpression, + PropertyAssignment, + PropertyDeclaration, + PropertyName, + PropertySignature, + PseudoBigInt, + pseudoBigIntToString, + PunctuationSyntaxKind, + pushIfUnique, + QualifiedName, + QuestionToken, + rangeEquals, + rangeOfNode, + rangeOfTypeParameters, + ReadonlyKeyword, + reduceLeft, + RegularExpressionLiteral, + RelationComparisonResult, + relativeComplement, + removeExtension, + removePrefix, + replaceElement, + resolutionExtensionIsTSOrJson, + ResolutionMode, + ResolvedModuleFull, + ResolvedType, + resolvingEmptyArray, + RestTypeNode, + ReturnStatement, + ReverseMappedSymbol, + ReverseMappedType, + sameMap, + SatisfiesExpression, + Scanner, + scanTokenAtPosition, + ScriptKind, + ScriptTarget, + SetAccessorDeclaration, + setCommentRange as setCommentRangeWorker, + setEmitFlags, + setIdentifierTypeArguments, + setNodeFlags, + setOriginalNode, + setParent, + setSyntheticLeadingComments, + setTextRange as setTextRangeWorker, + setTextRangePosEnd, + setValueDeclaration, + ShorthandPropertyAssignment, + shouldAllowImportingTsExtension, + shouldPreserveConstEnums, + Signature, + SignatureDeclaration, + SignatureFlags, + SignatureKind, + singleElementArray, + SingleSignatureType, + skipOuterExpressions, + skipParentheses, + skipTrivia, + skipTypeChecking, + skipTypeParentheses, + some, + SourceFile, + SpreadAssignment, + SpreadElement, + startsWith, + Statement, + StringLiteral, + StringLiteralLike, + StringLiteralType, + StringMappingType, + stripQuotes, + StructuredType, + SubstitutionType, + SuperCall, + SwitchStatement, + Symbol, + SymbolAccessibility, + SymbolAccessibilityResult, + SymbolFlags, + SymbolFormatFlags, + SymbolId, + SymbolLinks, + symbolName, + SymbolTable, + SymbolTracker, + SymbolVisibilityResult, + SyntaxKind, + SyntheticDefaultModuleType, + SyntheticExpression, + TaggedTemplateExpression, + TemplateExpression, + TemplateLiteralType, + TemplateLiteralTypeNode, + Ternary, + textRangeContainsPositionInclusive, + TextSpan, + textSpanContainsPosition, + textSpanEnd, + ThisExpression, + ThisTypeNode, + ThrowStatement, + TokenFlags, + tokenToString, + tracing, + TracingNode, + TrackedSymbol, + TransientSymbol, + TransientSymbolLinks, + tryAddToSet, + tryCast, + tryExtractTSExtension, + tryGetClassImplementingOrExtendingExpressionWithTypeArguments, + tryGetExtensionFromPath, + tryGetJSDocSatisfiesTypeNode, + tryGetModuleSpecifierFromDeclaration, + tryGetPropertyAccessOrIdentifierToString, + TryStatement, + TupleType, + TupleTypeNode, + TupleTypeReference, + Type, + TypeAliasDeclaration, + TypeAssertion, + TypeChecker, + TypeCheckerHost, + TypeComparer, + TypeElement, + TypeFlags, + TypeFormatFlags, + TypeId, + TypeLiteralNode, + TypeMapKind, + TypeMapper, + TypeNode, + TypeNodeSyntaxKind, + TypeOfExpression, + TypeOnlyAliasDeclaration, + TypeOnlyCompatibleAliasDeclaration, + TypeOperatorNode, + TypeParameter, + TypeParameterDeclaration, + TypePredicate, + TypePredicateKind, + TypePredicateNode, + TypeQueryNode, + TypeReference, + TypeReferenceNode, + TypeReferenceSerializationKind, + TypeReferenceType, + TypeVariable, + unescapeLeadingUnderscores, + UnionOrIntersectionType, + UnionOrIntersectionTypeNode, + UnionReduction, + UnionType, + UnionTypeNode, + UniqueESSymbolType, + usingSingleLineStringWriter, + VariableDeclaration, + VariableDeclarationList, + VariableLikeDeclaration, + VariableStatement, + VarianceFlags, + visitEachChild as visitEachChildWorker, + visitNode, + visitNodes, + Visitor, + VisitResult, + VoidExpression, + walkUpBindingElementsAndPatterns, + walkUpOuterExpressions, + walkUpParenthesizedExpressions, + walkUpParenthesizedTypes, + walkUpParenthesizedTypesAndGetParentAndChild, + WhileStatement, + WideningContext, + WithStatement, + YieldExpression, +} from "./_namespaces/ts.js"; +import * as moduleSpecifiers from "./_namespaces/ts.moduleSpecifiers.js"; +import * as performance from "./_namespaces/ts.performance.js"; + +const ambientModuleSymbolRegex = /^".+"$/; +const anon = "(anonymous)" as __String & string; + +const enum ReferenceHint { + Unspecified, + Identifier, + Property, + ExportAssignment, + Jsx, + AsyncFunction, + ExportImportEquals, + ExportSpecifier, + Decorator, +} + +let nextSymbolId = 1; +let nextNodeId = 1; +let nextMergeId = 1; +let nextFlowId = 1; + +const enum IterationUse { + AllowsSyncIterablesFlag = 1 << 0, + AllowsAsyncIterablesFlag = 1 << 1, + AllowsStringInputFlag = 1 << 2, + ForOfFlag = 1 << 3, + YieldStarFlag = 1 << 4, + SpreadFlag = 1 << 5, + DestructuringFlag = 1 << 6, + PossiblyOutOfBounds = 1 << 7, + + // Spread, Destructuring, Array element assignment + Element = AllowsSyncIterablesFlag, + Spread = AllowsSyncIterablesFlag | SpreadFlag, + Destructuring = AllowsSyncIterablesFlag | DestructuringFlag, + + ForOf = AllowsSyncIterablesFlag | AllowsStringInputFlag | ForOfFlag, + ForAwaitOf = AllowsSyncIterablesFlag | AllowsAsyncIterablesFlag | AllowsStringInputFlag | ForOfFlag, + + YieldStar = AllowsSyncIterablesFlag | YieldStarFlag, + AsyncYieldStar = AllowsSyncIterablesFlag | AllowsAsyncIterablesFlag | YieldStarFlag, + + GeneratorReturnType = AllowsSyncIterablesFlag, + AsyncGeneratorReturnType = AllowsAsyncIterablesFlag, +} + +const enum IterationTypeKind { + Yield, + Return, + Next, +} + +interface IterationTypesResolver { + iterableCacheKey: "iterationTypesOfAsyncIterable" | "iterationTypesOfIterable"; + iteratorCacheKey: "iterationTypesOfAsyncIterator" | "iterationTypesOfIterator"; + iteratorSymbolName: "asyncIterator" | "iterator"; + getGlobalIteratorType: (reportErrors: boolean) => GenericType; + getGlobalIterableType: (reportErrors: boolean) => GenericType; + getGlobalIterableIteratorType: (reportErrors: boolean) => GenericType; + getGlobalGeneratorType: (reportErrors: boolean) => GenericType; + resolveIterationType: (type: Type, errorNode: Node | undefined) => Type | undefined; + mustHaveANextMethodDiagnostic: DiagnosticMessage; + mustBeAMethodDiagnostic: DiagnosticMessage; + mustHaveAValueDiagnostic: DiagnosticMessage; +} + +const enum WideningKind { + Normal, + FunctionReturn, + GeneratorNext, + GeneratorYield, +} + +// dprint-ignore +/** @internal */ +export const enum TypeFacts { + None = 0, + TypeofEQString = 1 << 0, // typeof x === "string" + TypeofEQNumber = 1 << 1, // typeof x === "number" + TypeofEQBigInt = 1 << 2, // typeof x === "bigint" + TypeofEQBoolean = 1 << 3, // typeof x === "boolean" + TypeofEQSymbol = 1 << 4, // typeof x === "symbol" + TypeofEQObject = 1 << 5, // typeof x === "object" + TypeofEQFunction = 1 << 6, // typeof x === "function" + TypeofEQHostObject = 1 << 7, // typeof x === "xxx" + TypeofNEString = 1 << 8, // typeof x !== "string" + TypeofNENumber = 1 << 9, // typeof x !== "number" + TypeofNEBigInt = 1 << 10, // typeof x !== "bigint" + TypeofNEBoolean = 1 << 11, // typeof x !== "boolean" + TypeofNESymbol = 1 << 12, // typeof x !== "symbol" + TypeofNEObject = 1 << 13, // typeof x !== "object" + TypeofNEFunction = 1 << 14, // typeof x !== "function" + TypeofNEHostObject = 1 << 15, // typeof x !== "xxx" + EQUndefined = 1 << 16, // x === undefined + EQNull = 1 << 17, // x === null + EQUndefinedOrNull = 1 << 18, // x === undefined / x === null + NEUndefined = 1 << 19, // x !== undefined + NENull = 1 << 20, // x !== null + NEUndefinedOrNull = 1 << 21, // x != undefined / x != null + Truthy = 1 << 22, // x + Falsy = 1 << 23, // !x + IsUndefined = 1 << 24, // Contains undefined or intersection with undefined + IsNull = 1 << 25, // Contains null or intersection with null + IsUndefinedOrNull = IsUndefined | IsNull, + All = (1 << 27) - 1, + // The following members encode facts about particular kinds of types for use in the getTypeFacts function. + // The presence of a particular fact means that the given test is true for some (and possibly all) values + // of that kind of type. + BaseStringStrictFacts = TypeofEQString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseStringFacts = BaseStringStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + StringStrictFacts = BaseStringStrictFacts | Truthy | Falsy, + StringFacts = BaseStringFacts | Truthy, + EmptyStringStrictFacts = BaseStringStrictFacts | Falsy, + EmptyStringFacts = BaseStringFacts, + NonEmptyStringStrictFacts = BaseStringStrictFacts | Truthy, + NonEmptyStringFacts = BaseStringFacts | Truthy, + BaseNumberStrictFacts = TypeofEQNumber | TypeofNEString | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseNumberFacts = BaseNumberStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + NumberStrictFacts = BaseNumberStrictFacts | Truthy | Falsy, + NumberFacts = BaseNumberFacts | Truthy, + ZeroNumberStrictFacts = BaseNumberStrictFacts | Falsy, + ZeroNumberFacts = BaseNumberFacts, + NonZeroNumberStrictFacts = BaseNumberStrictFacts | Truthy, + NonZeroNumberFacts = BaseNumberFacts | Truthy, + BaseBigIntStrictFacts = TypeofEQBigInt | TypeofNEString | TypeofNENumber | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseBigIntFacts = BaseBigIntStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + BigIntStrictFacts = BaseBigIntStrictFacts | Truthy | Falsy, + BigIntFacts = BaseBigIntFacts | Truthy, + ZeroBigIntStrictFacts = BaseBigIntStrictFacts | Falsy, + ZeroBigIntFacts = BaseBigIntFacts, + NonZeroBigIntStrictFacts = BaseBigIntStrictFacts | Truthy, + NonZeroBigIntFacts = BaseBigIntFacts | Truthy, + BaseBooleanStrictFacts = TypeofEQBoolean | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull, + BaseBooleanFacts = BaseBooleanStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + BooleanStrictFacts = BaseBooleanStrictFacts | Truthy | Falsy, + BooleanFacts = BaseBooleanFacts | Truthy, + FalseStrictFacts = BaseBooleanStrictFacts | Falsy, + FalseFacts = BaseBooleanFacts, + TrueStrictFacts = BaseBooleanStrictFacts | Truthy, + TrueFacts = BaseBooleanFacts | Truthy, + SymbolStrictFacts = TypeofEQSymbol | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | NEUndefined | NENull | NEUndefinedOrNull | Truthy, + SymbolFacts = SymbolStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + ObjectStrictFacts = TypeofEQObject | TypeofEQHostObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEFunction | NEUndefined | NENull | NEUndefinedOrNull | Truthy, + ObjectFacts = ObjectStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + FunctionStrictFacts = TypeofEQFunction | TypeofEQHostObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | NEUndefined | NENull | NEUndefinedOrNull | Truthy, + FunctionFacts = FunctionStrictFacts | EQUndefined | EQNull | EQUndefinedOrNull | Falsy, + VoidFacts = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | EQUndefined | EQUndefinedOrNull | NENull | Falsy, + UndefinedFacts = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | TypeofNEHostObject | EQUndefined | EQUndefinedOrNull | NENull | Falsy | IsUndefined, + NullFacts = TypeofEQObject | TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEFunction | TypeofNEHostObject | EQNull | EQUndefinedOrNull | NEUndefined | Falsy | IsNull, + EmptyObjectStrictFacts = All & ~(EQUndefined | EQNull | EQUndefinedOrNull | IsUndefinedOrNull), + EmptyObjectFacts = All & ~IsUndefinedOrNull, + UnknownFacts = All & ~IsUndefinedOrNull, + AllTypeofNE = TypeofNEString | TypeofNENumber | TypeofNEBigInt | TypeofNEBoolean | TypeofNESymbol | TypeofNEObject | TypeofNEFunction | NEUndefined, + // Masks + OrFactsMask = TypeofEQFunction | TypeofNEObject, + AndFactsMask = All & ~OrFactsMask, +} + +const typeofNEFacts: ReadonlyMap = new Map(Object.entries({ + string: TypeFacts.TypeofNEString, + number: TypeFacts.TypeofNENumber, + bigint: TypeFacts.TypeofNEBigInt, + boolean: TypeFacts.TypeofNEBoolean, + symbol: TypeFacts.TypeofNESymbol, + undefined: TypeFacts.NEUndefined, + object: TypeFacts.TypeofNEObject, + function: TypeFacts.TypeofNEFunction, +})); + +type TypeSystemEntity = Node | Symbol | Type | Signature; + +const enum TypeSystemPropertyName { + Type, + ResolvedBaseConstructorType, + DeclaredType, + ResolvedReturnType, + ImmediateBaseConstraint, + ResolvedTypeArguments, + ResolvedBaseTypes, + WriteType, + ParameterInitializerContainsUndefined, +} + +// dprint-ignore +/** @internal */ +export const enum CheckMode { + Normal = 0, // Normal type checking + Contextual = 1 << 0, // Explicitly assigned contextual type, therefore not cacheable + Inferential = 1 << 1, // Inferential typing + SkipContextSensitive = 1 << 2, // Skip context sensitive function expressions + SkipGenericFunctions = 1 << 3, // Skip single signature generic functions + IsForSignatureHelp = 1 << 4, // Call resolution for purposes of signature help + RestBindingElement = 1 << 5, // Checking a type that is going to be used to determine the type of a rest binding element + // e.g. in `const { a, ...rest } = foo`, when checking the type of `foo` to determine the type of `rest`, + // we need to preserve generic types instead of substituting them for constraints + TypeOnly = 1 << 6, // Called from getTypeOfExpression, diagnostics may be omitted +} + +/** @internal */ +export const enum SignatureCheckMode { + None = 0, + BivariantCallback = 1 << 0, + StrictCallback = 1 << 1, + IgnoreReturnTypes = 1 << 2, + StrictArity = 1 << 3, + StrictTopSignature = 1 << 4, + Callback = BivariantCallback | StrictCallback, +} + +const enum IntersectionState { + None = 0, + Source = 1 << 0, // Source type is a constituent of an outer intersection + Target = 1 << 1, // Target type is a constituent of an outer intersection +} + +const enum RecursionFlags { + None = 0, + Source = 1 << 0, + Target = 1 << 1, + Both = Source | Target, +} + +const enum MappedTypeModifiers { + IncludeReadonly = 1 << 0, + ExcludeReadonly = 1 << 1, + IncludeOptional = 1 << 2, + ExcludeOptional = 1 << 3, +} + +const enum MappedTypeNameTypeKind { + None, + Filtering, + Remapping, +} + +const enum ExpandingFlags { + None = 0, + Source = 1, + Target = 1 << 1, + Both = Source | Target, +} + +const enum MembersOrExportsResolutionKind { + resolvedExports = "resolvedExports", + resolvedMembers = "resolvedMembers", +} + +const enum UnusedKind { + Local, + Parameter, +} + +/** @param containingNode Node to check for parse error */ +type AddUnusedDiagnostic = (containingNode: Node, type: UnusedKind, diagnostic: DiagnosticWithLocation) => void; + +const isNotOverloadAndNotAccessor = and(isNotOverload, isNotAccessor); + +const enum DeclarationMeaning { + GetAccessor = 1, + SetAccessor = 2, + PropertyAssignment = 4, + Method = 8, + PrivateStatic = 16, + GetOrSetAccessor = GetAccessor | SetAccessor, + PropertyAssignmentOrMethod = PropertyAssignment | Method, +} + +const enum DeclarationSpaces { + None = 0, + ExportValue = 1 << 0, + ExportType = 1 << 1, + ExportNamespace = 1 << 2, +} + +const enum MinArgumentCountFlags { + None = 0, + StrongArityForUntypedJS = 1 << 0, + VoidIsNonOptional = 1 << 1, +} + +const enum IntrinsicTypeKind { + Uppercase, + Lowercase, + Capitalize, + Uncapitalize, + NoInfer, +} + +const intrinsicTypeKinds: ReadonlyMap = new Map(Object.entries({ + Uppercase: IntrinsicTypeKind.Uppercase, + Lowercase: IntrinsicTypeKind.Lowercase, + Capitalize: IntrinsicTypeKind.Capitalize, + Uncapitalize: IntrinsicTypeKind.Uncapitalize, + NoInfer: IntrinsicTypeKind.NoInfer, +})); + +const SymbolLinks = class implements SymbolLinks { + declare _symbolLinksBrand: any; +}; + +function NodeLinks(this: NodeLinks) { + this.flags = NodeCheckFlags.None; +} + +/** @internal */ +export function getNodeId(node: Node): number { + if (!node.id) { + node.id = nextNodeId; + nextNodeId++; + } + return node.id; +} + +/** @internal */ +export function getSymbolId(symbol: Symbol): SymbolId { + if (!symbol.id) { + symbol.id = nextSymbolId; + nextSymbolId++; + } + + return symbol.id; +} + +/** @internal */ +export function isInstantiatedModule(node: ModuleDeclaration, preserveConstEnums: boolean) { + const moduleState = getModuleInstanceState(node); + return moduleState === ModuleInstanceState.Instantiated || + (preserveConstEnums && moduleState === ModuleInstanceState.ConstEnumOnly); +} + +/** @internal */ +export function createTypeChecker(host: TypeCheckerHost): TypeChecker { + // Why var? It avoids TDZ checks in the runtime which can be costly. + // See: https://github.com/microsoft/TypeScript/issues/52924 + /* eslint-disable no-var */ + var deferredDiagnosticsCallbacks: (() => void)[] = []; + + var addLazyDiagnostic = (arg: () => void) => { + deferredDiagnosticsCallbacks.push(arg); + }; + + // Cancellation that controls whether or not we can cancel in the middle of type checking. + // In general cancelling is *not* safe for the type checker. We might be in the middle of + // computing something, and we will leave our internals in an inconsistent state. Callers + // who set the cancellation token should catch if a cancellation exception occurs, and + // should throw away and create a new TypeChecker. + // + // Currently we only support setting the cancellation token when getting diagnostics. This + // is because diagnostics can be quite expensive, and we want to allow hosts to bail out if + // they no longer need the information (for example, if the user started editing again). + var cancellationToken: CancellationToken | undefined; + + var scanner: Scanner | undefined; + + var Symbol = objectAllocator.getSymbolConstructor(); + var Type = objectAllocator.getTypeConstructor(); + var Signature = objectAllocator.getSignatureConstructor(); + + var typeCount = 0; + var symbolCount = 0; + var totalInstantiationCount = 0; + var instantiationCount = 0; + var instantiationDepth = 0; + var inlineLevel = 0; + var currentNode: Node | undefined; + var varianceTypeParameter: TypeParameter | undefined; + var isInferencePartiallyBlocked = false; + + var emptySymbols = createSymbolTable(); + var arrayVariances = [VarianceFlags.Covariant]; + + var compilerOptions = host.getCompilerOptions(); + var languageVersion = getEmitScriptTarget(compilerOptions); + var moduleKind = getEmitModuleKind(compilerOptions); + var legacyDecorators = !!compilerOptions.experimentalDecorators; + var useDefineForClassFields = getUseDefineForClassFields(compilerOptions); + var emitStandardClassFields = getEmitStandardClassFields(compilerOptions); + var allowSyntheticDefaultImports = getAllowSyntheticDefaultImports(compilerOptions); + var strictNullChecks = getStrictOptionValue(compilerOptions, "strictNullChecks"); + var strictFunctionTypes = getStrictOptionValue(compilerOptions, "strictFunctionTypes"); + var strictBindCallApply = getStrictOptionValue(compilerOptions, "strictBindCallApply"); + var strictPropertyInitialization = getStrictOptionValue(compilerOptions, "strictPropertyInitialization"); + var noImplicitAny = getStrictOptionValue(compilerOptions, "noImplicitAny"); + var noImplicitThis = getStrictOptionValue(compilerOptions, "noImplicitThis"); + var useUnknownInCatchVariables = getStrictOptionValue(compilerOptions, "useUnknownInCatchVariables"); + var exactOptionalPropertyTypes = compilerOptions.exactOptionalPropertyTypes; + + var checkBinaryExpression = createCheckBinaryExpression(); + var emitResolver = createResolver(); + var nodeBuilder = createNodeBuilder(); + var syntacticNodeBuilder = createSyntacticTypeNodeBuilder(compilerOptions, { + isEntityNameVisible, + isExpandoFunctionDeclaration, + getAllAccessorDeclarations: getAllAccessorDeclarationsForDeclaration, + requiresAddingImplicitUndefined, + isUndefinedIdentifierExpression(node: Identifier) { + Debug.assert(isExpressionNode(node)); + return getSymbolAtLocation(node) === undefinedSymbol; + }, + isDefinitelyReferenceToGlobalSymbolObject, + }); + var evaluate = createEvaluator({ + evaluateElementAccessExpression, + evaluateEntityNameExpression, + }); + + var globals = createSymbolTable(); + var undefinedSymbol = createSymbol(SymbolFlags.Property, "undefined" as __String); + undefinedSymbol.declarations = []; + + var globalThisSymbol = createSymbol(SymbolFlags.Module, "globalThis" as __String, CheckFlags.Readonly); + globalThisSymbol.exports = globals; + globalThisSymbol.declarations = []; + globals.set(globalThisSymbol.escapedName, globalThisSymbol); + + var argumentsSymbol = createSymbol(SymbolFlags.Property, "arguments" as __String); + var requireSymbol = createSymbol(SymbolFlags.Property, "require" as __String); + var isolatedModulesLikeFlagName = compilerOptions.verbatimModuleSyntax ? "verbatimModuleSyntax" : "isolatedModules"; + var canCollectSymbolAliasAccessabilityData = !compilerOptions.verbatimModuleSyntax; + + /** This will be set during calls to `getResolvedSignature` where services determines an apparent number of arguments greater than what is actually provided. */ + var apparentArgumentCount: number | undefined; + + var lastGetCombinedNodeFlagsNode: Node | undefined; + var lastGetCombinedNodeFlagsResult = NodeFlags.None; + var lastGetCombinedModifierFlagsNode: Declaration | undefined; + var lastGetCombinedModifierFlagsResult = ModifierFlags.None; + var resolveName = createNameResolver({ + compilerOptions, + requireSymbol, + argumentsSymbol, + globals, + getSymbolOfDeclaration, + error, + getRequiresScopeChangeCache, + setRequiresScopeChangeCache, + lookup: getSymbol, + onPropertyWithInvalidInitializer: checkAndReportErrorForInvalidInitializer, + onFailedToResolveSymbol, + onSuccessfullyResolvedSymbol, + }); + + var resolveNameForSymbolSuggestion = createNameResolver({ + compilerOptions, + requireSymbol, + argumentsSymbol, + globals, + getSymbolOfDeclaration, + error, + getRequiresScopeChangeCache, + setRequiresScopeChangeCache, + lookup: getSuggestionForSymbolNameLookup, + }); + // for public members that accept a Node or one of its subtypes, we must guard against + // synthetic nodes created during transformations by calling `getParseTreeNode`. + // for most of these, we perform the guard only on `checker` to avoid any possible + // extra cost of calling `getParseTreeNode` when calling these functions from inside the + // checker. + const checker: TypeChecker = { + getNodeCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.nodeCount, 0), + getIdentifierCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.identifierCount, 0), + getSymbolCount: () => reduceLeft(host.getSourceFiles(), (n, s) => n + s.symbolCount, symbolCount), + getTypeCount: () => typeCount, + getInstantiationCount: () => totalInstantiationCount, + getRelationCacheSizes: () => ({ + assignable: assignableRelation.size, + identity: identityRelation.size, + subtype: subtypeRelation.size, + strictSubtype: strictSubtypeRelation.size, + }), + isUndefinedSymbol: symbol => symbol === undefinedSymbol, + isArgumentsSymbol: symbol => symbol === argumentsSymbol, + isUnknownSymbol: symbol => symbol === unknownSymbol, + getMergedSymbol, + symbolIsValue, + getDiagnostics, + getGlobalDiagnostics, + getRecursionIdentity, + getUnmatchedProperties, + getTypeOfSymbolAtLocation: (symbol, locationIn) => { + const location = getParseTreeNode(locationIn); + return location ? getTypeOfSymbolAtLocation(symbol, location) : errorType; + }, + getTypeOfSymbol, + getSymbolsOfParameterPropertyDeclaration: (parameterIn, parameterName) => { + const parameter = getParseTreeNode(parameterIn, isParameter); + if (parameter === undefined) return Debug.fail("Cannot get symbols of a synthetic parameter that cannot be resolved to a parse-tree node."); + Debug.assert(isParameterPropertyDeclaration(parameter, parameter.parent)); + return getSymbolsOfParameterPropertyDeclaration(parameter, escapeLeadingUnderscores(parameterName)); + }, + getDeclaredTypeOfSymbol, + getPropertiesOfType, + getPropertyOfType: (type, name) => getPropertyOfType(type, escapeLeadingUnderscores(name)), + getPrivateIdentifierPropertyOfType: (leftType: Type, name: string, location: Node) => { + const node = getParseTreeNode(location); + if (!node) { + return undefined; + } + const propName = escapeLeadingUnderscores(name); + const lexicallyScopedIdentifier = lookupSymbolForPrivateIdentifierDeclaration(propName, node); + return lexicallyScopedIdentifier ? getPrivateIdentifierPropertyOfType(leftType, lexicallyScopedIdentifier) : undefined; + }, + getTypeOfPropertyOfType: (type, name) => getTypeOfPropertyOfType(type, escapeLeadingUnderscores(name)), + getIndexInfoOfType: (type, kind) => getIndexInfoOfType(type, kind === IndexKind.String ? stringType : numberType), + getIndexInfosOfType, + getIndexInfosOfIndexSymbol, + getSignaturesOfType, + getIndexTypeOfType: (type, kind) => getIndexTypeOfType(type, kind === IndexKind.String ? stringType : numberType), + getIndexType: type => getIndexType(type), + getBaseTypes, + getBaseTypeOfLiteralType, + getWidenedType, + getWidenedLiteralType, + getTypeFromTypeNode: nodeIn => { + const node = getParseTreeNode(nodeIn, isTypeNode); + return node ? getTypeFromTypeNode(node) : errorType; + }, + getParameterType: getTypeAtPosition, + getParameterIdentifierInfoAtPosition, + getPromisedTypeOfPromise, + getAwaitedType: type => getAwaitedType(type), + getReturnTypeOfSignature, + isNullableType, + getNullableType, + getNonNullableType, + getNonOptionalType: removeOptionalTypeMarker, + getTypeArguments, + typeToTypeNode: nodeBuilder.typeToTypeNode, + indexInfoToIndexSignatureDeclaration: nodeBuilder.indexInfoToIndexSignatureDeclaration, + signatureToSignatureDeclaration: nodeBuilder.signatureToSignatureDeclaration, + symbolToEntityName: nodeBuilder.symbolToEntityName, + symbolToExpression: nodeBuilder.symbolToExpression, + symbolToNode: nodeBuilder.symbolToNode, + symbolToTypeParameterDeclarations: nodeBuilder.symbolToTypeParameterDeclarations, + symbolToParameterDeclaration: nodeBuilder.symbolToParameterDeclaration, + typeParameterToDeclaration: nodeBuilder.typeParameterToDeclaration, + getSymbolsInScope: (locationIn, meaning) => { + const location = getParseTreeNode(locationIn); + return location ? getSymbolsInScope(location, meaning) : []; + }, + getSymbolAtLocation: nodeIn => { + const node = getParseTreeNode(nodeIn); + // set ignoreErrors: true because any lookups invoked by the API shouldn't cause any new errors + return node ? getSymbolAtLocation(node, /*ignoreErrors*/ true) : undefined; + }, + getIndexInfosAtLocation: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node ? getIndexInfosAtLocation(node) : undefined; + }, + getShorthandAssignmentValueSymbol: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node ? getShorthandAssignmentValueSymbol(node) : undefined; + }, + getExportSpecifierLocalTargetSymbol: nodeIn => { + const node = getParseTreeNode(nodeIn, isExportSpecifier); + return node ? getExportSpecifierLocalTargetSymbol(node) : undefined; + }, + getExportSymbolOfSymbol(symbol) { + return getMergedSymbol(symbol.exportSymbol || symbol); + }, + getTypeAtLocation: nodeIn => { + const node = getParseTreeNode(nodeIn); + return node ? getTypeOfNode(node) : errorType; + }, + getTypeOfAssignmentPattern: nodeIn => { + const node = getParseTreeNode(nodeIn, isAssignmentPattern); + return node && getTypeOfAssignmentPattern(node) || errorType; + }, + getPropertySymbolOfDestructuringAssignment: locationIn => { + const location = getParseTreeNode(locationIn, isIdentifier); + return location ? getPropertySymbolOfDestructuringAssignment(location) : undefined; + }, + signatureToString: (signature, enclosingDeclaration, flags, kind) => { + return signatureToString(signature, getParseTreeNode(enclosingDeclaration), flags, kind); + }, + typeToString: (type, enclosingDeclaration, flags) => { + return typeToString(type, getParseTreeNode(enclosingDeclaration), flags); + }, + symbolToString: (symbol, enclosingDeclaration, meaning, flags) => { + return symbolToString(symbol, getParseTreeNode(enclosingDeclaration), meaning, flags); + }, + typePredicateToString: (predicate, enclosingDeclaration, flags) => { + return typePredicateToString(predicate, getParseTreeNode(enclosingDeclaration), flags); + }, + writeSignature: (signature, enclosingDeclaration, flags, kind, writer) => { + return signatureToString(signature, getParseTreeNode(enclosingDeclaration), flags, kind, writer); + }, + writeType: (type, enclosingDeclaration, flags, writer) => { + return typeToString(type, getParseTreeNode(enclosingDeclaration), flags, writer); + }, + writeSymbol: (symbol, enclosingDeclaration, meaning, flags, writer) => { + return symbolToString(symbol, getParseTreeNode(enclosingDeclaration), meaning, flags, writer); + }, + writeTypePredicate: (predicate, enclosingDeclaration, flags, writer) => { + return typePredicateToString(predicate, getParseTreeNode(enclosingDeclaration), flags, writer); + }, + getAugmentedPropertiesOfType, + getRootSymbols, + getSymbolOfExpando, + getContextualType: (nodeIn: Expression, contextFlags?: ContextFlags) => { + const node = getParseTreeNode(nodeIn, isExpression); + if (!node) { + return undefined; + } + if (contextFlags! & ContextFlags.Completions) { + return runWithInferenceBlockedFromSourceNode(node, () => getContextualType(node, contextFlags)); + } + return getContextualType(node, contextFlags); + }, + getContextualTypeForObjectLiteralElement: nodeIn => { + const node = getParseTreeNode(nodeIn, isObjectLiteralElementLike); + return node ? getContextualTypeForObjectLiteralElement(node, /*contextFlags*/ undefined) : undefined; + }, + getContextualTypeForArgumentAtIndex: (nodeIn, argIndex) => { + const node = getParseTreeNode(nodeIn, isCallLikeExpression); + return node && getContextualTypeForArgumentAtIndex(node, argIndex); + }, + getContextualTypeForJsxAttribute: nodeIn => { + const node = getParseTreeNode(nodeIn, isJsxAttributeLike); + return node && getContextualTypeForJsxAttribute(node, /*contextFlags*/ undefined); + }, + isContextSensitive, + getTypeOfPropertyOfContextualType, + getFullyQualifiedName, + getResolvedSignature: (node, candidatesOutArray, argumentCount) => getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.Normal), + getCandidateSignaturesForStringLiteralCompletions, + getResolvedSignatureForSignatureHelp: (node, candidatesOutArray, argumentCount) => runWithoutResolvedSignatureCaching(node, () => getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.IsForSignatureHelp)), + getExpandedParameters, + hasEffectiveRestParameter, + containsArgumentsReference, + getConstantValue: nodeIn => { + const node = getParseTreeNode(nodeIn, canHaveConstantValue); + return node ? getConstantValue(node) : undefined; + }, + isValidPropertyAccess: (nodeIn, propertyName) => { + const node = getParseTreeNode(nodeIn, isPropertyAccessOrQualifiedNameOrImportTypeNode); + return !!node && isValidPropertyAccess(node, escapeLeadingUnderscores(propertyName)); + }, + isValidPropertyAccessForCompletions: (nodeIn, type, property) => { + const node = getParseTreeNode(nodeIn, isPropertyAccessExpression); + return !!node && isValidPropertyAccessForCompletions(node, type, property); + }, + getSignatureFromDeclaration: declarationIn => { + const declaration = getParseTreeNode(declarationIn, isFunctionLike); + return declaration ? getSignatureFromDeclaration(declaration) : undefined; + }, + isImplementationOfOverload: nodeIn => { + const node = getParseTreeNode(nodeIn, isFunctionLike); + return node ? isImplementationOfOverload(node) : undefined; + }, + getImmediateAliasedSymbol, + getAliasedSymbol: resolveAlias, + getEmitResolver, + requiresAddingImplicitUndefined, + getExportsOfModule: getExportsOfModuleAsArray, + getExportsAndPropertiesOfModule, + forEachExportAndPropertyOfModule, + getSymbolWalker: createGetSymbolWalker( + getRestTypeOfSignature, + getTypePredicateOfSignature, + getReturnTypeOfSignature, + getBaseTypes, + resolveStructuredTypeMembers, + getTypeOfSymbol, + getResolvedSymbol, + getConstraintOfTypeParameter, + getFirstIdentifier, + getTypeArguments, + ), + getAmbientModules, + getJsxIntrinsicTagNamesAt, + isOptionalParameter: nodeIn => { + const node = getParseTreeNode(nodeIn, isParameter); + return node ? isOptionalParameter(node) : false; + }, + tryGetMemberInModuleExports: (name, symbol) => tryGetMemberInModuleExports(escapeLeadingUnderscores(name), symbol), + tryGetMemberInModuleExportsAndProperties: (name, symbol) => tryGetMemberInModuleExportsAndProperties(escapeLeadingUnderscores(name), symbol), + tryFindAmbientModule: moduleName => tryFindAmbientModule(moduleName, /*withAugmentations*/ true), + tryFindAmbientModuleWithoutAugmentations: moduleName => { + // we deliberately exclude augmentations + // since we are only interested in declarations of the module itself + return tryFindAmbientModule(moduleName, /*withAugmentations*/ false); + }, + getApparentType, + getUnionType, + isTypeAssignableTo, + createAnonymousType, + createSignature, + createSymbol, + createIndexInfo, + getAnyType: () => anyType, + getStringType: () => stringType, + getStringLiteralType, + getNumberType: () => numberType, + getNumberLiteralType, + getBigIntType: () => bigintType, + getBigIntLiteralType, + createPromiseType, + createArrayType, + getElementTypeOfArrayType, + getBooleanType: () => booleanType, + getFalseType: (fresh?) => fresh ? falseType : regularFalseType, + getTrueType: (fresh?) => fresh ? trueType : regularTrueType, + getVoidType: () => voidType, + getUndefinedType: () => undefinedType, + getNullType: () => nullType, + getESSymbolType: () => esSymbolType, + getNeverType: () => neverType, + getOptionalType: () => optionalType, + getPromiseType: () => getGlobalPromiseType(/*reportErrors*/ false), + getPromiseLikeType: () => getGlobalPromiseLikeType(/*reportErrors*/ false), + getAsyncIterableType: () => { + const type = getGlobalAsyncIterableType(/*reportErrors*/ false); + if (type === emptyGenericType) return undefined; + return type; + }, + isSymbolAccessible, + isArrayType, + isTupleType, + isArrayLikeType, + isEmptyAnonymousObjectType, + isTypeInvalidDueToUnionDiscriminant, + getExactOptionalProperties, + getAllPossiblePropertiesOfTypes, + getSuggestedSymbolForNonexistentProperty, + getSuggestedSymbolForNonexistentJSXAttribute, + getSuggestedSymbolForNonexistentSymbol: (location, name, meaning) => getSuggestedSymbolForNonexistentSymbol(location, escapeLeadingUnderscores(name), meaning), + getSuggestedSymbolForNonexistentModule, + getSuggestedSymbolForNonexistentClassMember, + getBaseConstraintOfType, + getDefaultFromTypeParameter: type => type && type.flags & TypeFlags.TypeParameter ? getDefaultFromTypeParameter(type as TypeParameter) : undefined, + resolveName(name, location, meaning, excludeGlobals) { + return resolveName(location, escapeLeadingUnderscores(name), meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false, excludeGlobals); + }, + getJsxNamespace: n => unescapeLeadingUnderscores(getJsxNamespace(n)), + getJsxFragmentFactory: n => { + const jsxFragmentFactory = getJsxFragmentFactoryEntity(n); + return jsxFragmentFactory && unescapeLeadingUnderscores(getFirstIdentifier(jsxFragmentFactory).escapedText); + }, + getAccessibleSymbolChain, + getTypePredicateOfSignature, + resolveExternalModuleName: moduleSpecifierIn => { + const moduleSpecifier = getParseTreeNode(moduleSpecifierIn, isExpression); + return moduleSpecifier && resolveExternalModuleName(moduleSpecifier, moduleSpecifier, /*ignoreErrors*/ true); + }, + resolveExternalModuleSymbol, + tryGetThisTypeAt: (nodeIn, includeGlobalThis, container) => { + const node = getParseTreeNode(nodeIn); + return node && tryGetThisTypeAt(node, includeGlobalThis, container); + }, + getTypeArgumentConstraint: nodeIn => { + const node = getParseTreeNode(nodeIn, isTypeNode); + return node && getTypeArgumentConstraint(node); + }, + getSuggestionDiagnostics: (fileIn, ct) => { + const file = getParseTreeNode(fileIn, isSourceFile) || Debug.fail("Could not determine parsed source file."); + if (skipTypeChecking(file, compilerOptions, host)) { + return emptyArray; + } + + let diagnostics: DiagnosticWithLocation[] | undefined; + try { + // Record the cancellation token so it can be checked later on during checkSourceElement. + // Do this in a finally block so we can ensure that it gets reset back to nothing after + // this call is done. + cancellationToken = ct; + + // Ensure file is type checked, with _eager_ diagnostic production, so identifiers are registered as potentially unused + checkSourceFileWithEagerDiagnostics(file); + Debug.assert(!!(getNodeLinks(file).flags & NodeCheckFlags.TypeChecked)); + + diagnostics = addRange(diagnostics, suggestionDiagnostics.getDiagnostics(file.fileName)); + checkUnusedIdentifiers(getPotentiallyUnusedIdentifiers(file), (containingNode, kind, diag) => { + if (!containsParseError(containingNode) && !unusedIsError(kind, !!(containingNode.flags & NodeFlags.Ambient))) { + (diagnostics || (diagnostics = [])).push({ ...diag, category: DiagnosticCategory.Suggestion }); + } + }); + + return diagnostics || emptyArray; + } + finally { + cancellationToken = undefined; + } + }, + + runWithCancellationToken: (token, callback) => { + try { + cancellationToken = token; + return callback(checker); + } + finally { + cancellationToken = undefined; + } + }, + + getLocalTypeParametersOfClassOrInterfaceOrTypeAlias, + isDeclarationVisible, + isPropertyAccessible, + getTypeOnlyAliasDeclaration, + getMemberOverrideModifierStatus, + isTypeParameterPossiblyReferenced, + typeHasCallOrConstructSignatures, + getSymbolFlags, + }; + + function getCandidateSignaturesForStringLiteralCompletions(call: CallLikeExpression, editingArgument: Node) { + const candidatesSet = new Set(); + const candidates: Signature[] = []; + + // first, get candidates when inference is blocked from the source node. + runWithInferenceBlockedFromSourceNode(editingArgument, () => getResolvedSignatureWorker(call, candidates, /*argumentCount*/ undefined, CheckMode.Normal)); + for (const candidate of candidates) { + candidatesSet.add(candidate); + } + + // reset candidates for second pass + candidates.length = 0; + + // next, get candidates where the source node is considered for inference. + runWithoutResolvedSignatureCaching(editingArgument, () => getResolvedSignatureWorker(call, candidates, /*argumentCount*/ undefined, CheckMode.Normal)); + for (const candidate of candidates) { + candidatesSet.add(candidate); + } + + return arrayFrom(candidatesSet); + } + + function runWithoutResolvedSignatureCaching(node: Node | undefined, fn: () => T): T { + node = findAncestor(node, isCallLikeOrFunctionLikeExpression); + if (node) { + const cachedResolvedSignatures = []; + const cachedTypes = []; + while (node) { + const nodeLinks = getNodeLinks(node); + cachedResolvedSignatures.push([nodeLinks, nodeLinks.resolvedSignature] as const); + nodeLinks.resolvedSignature = undefined; + if (isFunctionExpressionOrArrowFunction(node)) { + const symbolLinks = getSymbolLinks(getSymbolOfDeclaration(node)); + const type = symbolLinks.type; + cachedTypes.push([symbolLinks, type] as const); + symbolLinks.type = undefined; + } + node = findAncestor(node.parent, isCallLikeOrFunctionLikeExpression); + } + const result = fn(); + for (const [nodeLinks, resolvedSignature] of cachedResolvedSignatures) { + nodeLinks.resolvedSignature = resolvedSignature; + } + for (const [symbolLinks, type] of cachedTypes) { + symbolLinks.type = type; + } + return result; + } + return fn(); + } + + function runWithInferenceBlockedFromSourceNode(node: Node | undefined, fn: () => T): T { + const containingCall = findAncestor(node, isCallLikeExpression); + if (containingCall) { + let toMarkSkip = node!; + do { + getNodeLinks(toMarkSkip).skipDirectInference = true; + toMarkSkip = toMarkSkip.parent; + } + while (toMarkSkip && toMarkSkip !== containingCall); + } + + isInferencePartiallyBlocked = true; + const result = runWithoutResolvedSignatureCaching(node, fn); + isInferencePartiallyBlocked = false; + + if (containingCall) { + let toMarkSkip = node!; + do { + getNodeLinks(toMarkSkip).skipDirectInference = undefined; + toMarkSkip = toMarkSkip.parent; + } + while (toMarkSkip && toMarkSkip !== containingCall); + } + return result; + } + + function getResolvedSignatureWorker(nodeIn: CallLikeExpression, candidatesOutArray: Signature[] | undefined, argumentCount: number | undefined, checkMode: CheckMode): Signature | undefined { + const node = getParseTreeNode(nodeIn, isCallLikeExpression); + apparentArgumentCount = argumentCount; + const res = !node ? undefined : getResolvedSignature(node, candidatesOutArray, checkMode); + apparentArgumentCount = undefined; + return res; + } + + var tupleTypes = new Map(); + var unionTypes = new Map(); + var unionOfUnionTypes = new Map(); + var intersectionTypes = new Map(); + var stringLiteralTypes = new Map(); + var numberLiteralTypes = new Map(); + var bigIntLiteralTypes = new Map(); + var enumLiteralTypes = new Map(); + var indexedAccessTypes = new Map(); + var templateLiteralTypes = new Map(); + var stringMappingTypes = new Map(); + var substitutionTypes = new Map(); + var subtypeReductionCache = new Map(); + var decoratorContextOverrideTypeCache = new Map(); + var cachedTypes = new Map(); + var evolvingArrayTypes: EvolvingArrayType[] = []; + var undefinedProperties: SymbolTable = new Map(); + var markerTypes = new Set(); + + var unknownSymbol = createSymbol(SymbolFlags.Property, "unknown" as __String); + var resolvingSymbol = createSymbol(0, InternalSymbolName.Resolving); + var unresolvedSymbols = new Map(); + var errorTypes = new Map(); + + // We specifically create the `undefined` and `null` types before any other types that can occur in + // unions such that they are given low type IDs and occur first in the sorted list of union constituents. + // We can then just examine the first constituent(s) of a union to check for their presence. + + var seenIntrinsicNames = new Set(); + + var anyType = createIntrinsicType(TypeFlags.Any, "any"); + var autoType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.NonInferrableType, "auto"); + var wildcardType = createIntrinsicType(TypeFlags.Any, "any", /*objectFlags*/ undefined, "wildcard"); + var blockedStringType = createIntrinsicType(TypeFlags.Any, "any", /*objectFlags*/ undefined, "blocked string"); + var errorType = createIntrinsicType(TypeFlags.Any, "error"); + var unresolvedType = createIntrinsicType(TypeFlags.Any, "unresolved"); + var nonInferrableAnyType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.ContainsWideningType, "non-inferrable"); + var intrinsicMarkerType = createIntrinsicType(TypeFlags.Any, "intrinsic"); + var unknownType = createIntrinsicType(TypeFlags.Unknown, "unknown"); + var undefinedType = createIntrinsicType(TypeFlags.Undefined, "undefined"); + var undefinedWideningType = strictNullChecks ? undefinedType : createIntrinsicType(TypeFlags.Undefined, "undefined", ObjectFlags.ContainsWideningType, "widening"); + var missingType = createIntrinsicType(TypeFlags.Undefined, "undefined", /*objectFlags*/ undefined, "missing"); + var undefinedOrMissingType = exactOptionalPropertyTypes ? missingType : undefinedType; + var optionalType = createIntrinsicType(TypeFlags.Undefined, "undefined", /*objectFlags*/ undefined, "optional"); + var nullType = createIntrinsicType(TypeFlags.Null, "null"); + var nullWideningType = strictNullChecks ? nullType : createIntrinsicType(TypeFlags.Null, "null", ObjectFlags.ContainsWideningType, "widening"); + var stringType = createIntrinsicType(TypeFlags.String, "string"); + var numberType = createIntrinsicType(TypeFlags.Number, "number"); + var bigintType = createIntrinsicType(TypeFlags.BigInt, "bigint"); + var falseType = createIntrinsicType(TypeFlags.BooleanLiteral, "false", /*objectFlags*/ undefined, "fresh") as FreshableIntrinsicType; + var regularFalseType = createIntrinsicType(TypeFlags.BooleanLiteral, "false") as FreshableIntrinsicType; + var trueType = createIntrinsicType(TypeFlags.BooleanLiteral, "true", /*objectFlags*/ undefined, "fresh") as FreshableIntrinsicType; + var regularTrueType = createIntrinsicType(TypeFlags.BooleanLiteral, "true") as FreshableIntrinsicType; + trueType.regularType = regularTrueType; + trueType.freshType = trueType; + regularTrueType.regularType = regularTrueType; + regularTrueType.freshType = trueType; + falseType.regularType = regularFalseType; + falseType.freshType = falseType; + regularFalseType.regularType = regularFalseType; + regularFalseType.freshType = falseType; + var booleanType = getUnionType([regularFalseType, regularTrueType]); + var esSymbolType = createIntrinsicType(TypeFlags.ESSymbol, "symbol"); + var voidType = createIntrinsicType(TypeFlags.Void, "void"); + var neverType = createIntrinsicType(TypeFlags.Never, "never"); + var silentNeverType = createIntrinsicType(TypeFlags.Never, "never", ObjectFlags.NonInferrableType, "silent"); + var implicitNeverType = createIntrinsicType(TypeFlags.Never, "never", /*objectFlags*/ undefined, "implicit"); + var unreachableNeverType = createIntrinsicType(TypeFlags.Never, "never", /*objectFlags*/ undefined, "unreachable"); + var nonPrimitiveType = createIntrinsicType(TypeFlags.NonPrimitive, "object"); + var stringOrNumberType = getUnionType([stringType, numberType]); + var stringNumberSymbolType = getUnionType([stringType, numberType, esSymbolType]); + var numberOrBigIntType = getUnionType([numberType, bigintType]); + var templateConstraintType = getUnionType([stringType, numberType, booleanType, bigintType, nullType, undefinedType]) as UnionType; + var numericStringType = getTemplateLiteralType(["", ""], [numberType]); // The `${number}` type + + var restrictiveMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? getRestrictiveTypeParameter(t as TypeParameter) : t, () => "(restrictive mapper)"); + var permissiveMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? wildcardType : t, () => "(permissive mapper)"); + var uniqueLiteralType = createIntrinsicType(TypeFlags.Never, "never", /*objectFlags*/ undefined, "unique literal"); // `uniqueLiteralType` is a special `never` flagged by union reduction to behave as a literal + var uniqueLiteralMapper: TypeMapper = makeFunctionTypeMapper(t => t.flags & TypeFlags.TypeParameter ? uniqueLiteralType : t, () => "(unique literal mapper)"); // replace all type parameters with the unique literal type (disregarding constraints) + var outofbandVarianceMarkerHandler: ((onlyUnreliable: boolean) => void) | undefined; + var reportUnreliableMapper = makeFunctionTypeMapper(t => { + if (outofbandVarianceMarkerHandler && (t === markerSuperType || t === markerSubType || t === markerOtherType)) { + outofbandVarianceMarkerHandler(/*onlyUnreliable*/ true); + } + return t; + }, () => "(unmeasurable reporter)"); + var reportUnmeasurableMapper = makeFunctionTypeMapper(t => { + if (outofbandVarianceMarkerHandler && (t === markerSuperType || t === markerSubType || t === markerOtherType)) { + outofbandVarianceMarkerHandler(/*onlyUnreliable*/ false); + } + return t; + }, () => "(unreliable reporter)"); + + var emptyObjectType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var emptyJsxObjectType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + emptyJsxObjectType.objectFlags |= ObjectFlags.JsxAttributes; + + var emptyTypeLiteralSymbol = createSymbol(SymbolFlags.TypeLiteral, InternalSymbolName.Type); + emptyTypeLiteralSymbol.members = createSymbolTable(); + var emptyTypeLiteralType = createAnonymousType(emptyTypeLiteralSymbol, emptySymbols, emptyArray, emptyArray, emptyArray); + + var unknownEmptyObjectType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var unknownUnionType = strictNullChecks ? getUnionType([undefinedType, nullType, unknownEmptyObjectType]) : unknownType; + + var emptyGenericType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray) as ObjectType as GenericType; + emptyGenericType.instantiations = new Map(); + + var anyFunctionType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + // The anyFunctionType contains the anyFunctionType by definition. The flag is further propagated + // in getPropagatingFlagsOfTypes, and it is checked in inferFromTypes. + anyFunctionType.objectFlags |= ObjectFlags.NonInferrableType; + + var noConstraintType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var circularConstraintType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + var resolvingDefaultType = createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, emptyArray); + + var markerSuperType = createTypeParameter(); + var markerSubType = createTypeParameter(); + markerSubType.constraint = markerSuperType; + var markerOtherType = createTypeParameter(); + + var markerSuperTypeForCheck = createTypeParameter(); + var markerSubTypeForCheck = createTypeParameter(); + markerSubTypeForCheck.constraint = markerSuperTypeForCheck; + + var noTypePredicate = createTypePredicate(TypePredicateKind.Identifier, "<>", 0, anyType); + + var anySignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, anyType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + var unknownSignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, errorType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + var resolvingSignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, anyType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + var silentNeverSignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, silentNeverType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.None); + + var enumNumberIndexInfo = createIndexInfo(numberType, stringType, /*isReadonly*/ true); + + var iterationTypesCache = new Map(); // cache for common IterationTypes instances + var noIterationTypes: IterationTypes = { + get yieldType(): Type { + return Debug.fail("Not supported"); + }, + get returnType(): Type { + return Debug.fail("Not supported"); + }, + get nextType(): Type { + return Debug.fail("Not supported"); + }, + }; + + var anyIterationTypes = createIterationTypes(anyType, anyType, anyType); + var anyIterationTypesExceptNext = createIterationTypes(anyType, anyType, unknownType); + var defaultIterationTypes = createIterationTypes(neverType, anyType, undefinedType); // default iteration types for `Iterator`. + + var asyncIterationTypesResolver: IterationTypesResolver = { + iterableCacheKey: "iterationTypesOfAsyncIterable", + iteratorCacheKey: "iterationTypesOfAsyncIterator", + iteratorSymbolName: "asyncIterator", + getGlobalIteratorType: getGlobalAsyncIteratorType, + getGlobalIterableType: getGlobalAsyncIterableType, + getGlobalIterableIteratorType: getGlobalAsyncIterableIteratorType, + getGlobalGeneratorType: getGlobalAsyncGeneratorType, + resolveIterationType: (type, errorNode) => getAwaitedType(type, errorNode, Diagnostics.Type_of_await_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member), + mustHaveANextMethodDiagnostic: Diagnostics.An_async_iterator_must_have_a_next_method, + mustBeAMethodDiagnostic: Diagnostics.The_0_property_of_an_async_iterator_must_be_a_method, + mustHaveAValueDiagnostic: Diagnostics.The_type_returned_by_the_0_method_of_an_async_iterator_must_be_a_promise_for_a_type_with_a_value_property, + }; + + var syncIterationTypesResolver: IterationTypesResolver = { + iterableCacheKey: "iterationTypesOfIterable", + iteratorCacheKey: "iterationTypesOfIterator", + iteratorSymbolName: "iterator", + getGlobalIteratorType, + getGlobalIterableType, + getGlobalIterableIteratorType, + getGlobalGeneratorType, + resolveIterationType: (type, _errorNode) => type, + mustHaveANextMethodDiagnostic: Diagnostics.An_iterator_must_have_a_next_method, + mustBeAMethodDiagnostic: Diagnostics.The_0_property_of_an_iterator_must_be_a_method, + mustHaveAValueDiagnostic: Diagnostics.The_type_returned_by_the_0_method_of_an_iterator_must_have_a_value_property, + }; + + interface DuplicateInfoForSymbol { + readonly firstFileLocations: Declaration[]; + readonly secondFileLocations: Declaration[]; + readonly isBlockScoped: boolean; + } + interface DuplicateInfoForFiles { + readonly firstFile: SourceFile; + readonly secondFile: SourceFile; + /** Key is symbol name. */ + readonly conflictingSymbols: Map; + } + /** Key is "/path/to/a.ts|/path/to/b.ts". */ + var amalgamatedDuplicates: Map | undefined; + var reverseMappedCache = new Map(); + var ambientModulesCache: Symbol[] | undefined; + /** + * List of every ambient module with a "*" wildcard. + * Unlike other ambient modules, these can't be stored in `globals` because symbol tables only deal with exact matches. + * This is only used if there is no exact match. + */ + var patternAmbientModules: PatternAmbientModule[]; + var patternAmbientModuleAugmentations: Map | undefined; + + var globalObjectType: ObjectType; + var globalFunctionType: ObjectType; + var globalCallableFunctionType: ObjectType; + var globalNewableFunctionType: ObjectType; + var globalArrayType: GenericType; + var globalReadonlyArrayType: GenericType; + var globalStringType: ObjectType; + var globalNumberType: ObjectType; + var globalBooleanType: ObjectType; + var globalRegExpType: ObjectType; + var globalThisType: GenericType; + var anyArrayType: Type; + var autoArrayType: Type; + var anyReadonlyArrayType: Type; + var deferredGlobalNonNullableTypeAlias: Symbol; + + // The library files are only loaded when the feature is used. + // This allows users to just specify library files they want to used through --lib + // and they will not get an error from not having unrelated library files + var deferredGlobalESSymbolConstructorSymbol: Symbol | undefined; + var deferredGlobalESSymbolConstructorTypeSymbol: Symbol | undefined; + var deferredGlobalESSymbolType: ObjectType | undefined; + var deferredGlobalTypedPropertyDescriptorType: GenericType; + var deferredGlobalPromiseType: GenericType | undefined; + var deferredGlobalPromiseLikeType: GenericType | undefined; + var deferredGlobalPromiseConstructorSymbol: Symbol | undefined; + var deferredGlobalPromiseConstructorLikeType: ObjectType | undefined; + var deferredGlobalIterableType: GenericType | undefined; + var deferredGlobalIteratorType: GenericType | undefined; + var deferredGlobalIterableIteratorType: GenericType | undefined; + var deferredGlobalGeneratorType: GenericType | undefined; + var deferredGlobalIteratorYieldResultType: GenericType | undefined; + var deferredGlobalIteratorReturnResultType: GenericType | undefined; + var deferredGlobalAsyncIterableType: GenericType | undefined; + var deferredGlobalAsyncIteratorType: GenericType | undefined; + var deferredGlobalAsyncIterableIteratorType: GenericType | undefined; + var deferredGlobalAsyncGeneratorType: GenericType | undefined; + var deferredGlobalTemplateStringsArrayType: ObjectType | undefined; + var deferredGlobalImportMetaType: ObjectType; + var deferredGlobalImportMetaExpressionType: ObjectType; + var deferredGlobalImportCallOptionsType: ObjectType | undefined; + var deferredGlobalImportAttributesType: ObjectType | undefined; + var deferredGlobalDisposableType: ObjectType | undefined; + var deferredGlobalAsyncDisposableType: ObjectType | undefined; + var deferredGlobalExtractSymbol: Symbol | undefined; + var deferredGlobalOmitSymbol: Symbol | undefined; + var deferredGlobalAwaitedSymbol: Symbol | undefined; + var deferredGlobalBigIntType: ObjectType | undefined; + var deferredGlobalNaNSymbol: Symbol | undefined; + var deferredGlobalRecordSymbol: Symbol | undefined; + var deferredGlobalClassDecoratorContextType: GenericType | undefined; + var deferredGlobalClassMethodDecoratorContextType: GenericType | undefined; + var deferredGlobalClassGetterDecoratorContextType: GenericType | undefined; + var deferredGlobalClassSetterDecoratorContextType: GenericType | undefined; + var deferredGlobalClassAccessorDecoratorContextType: GenericType | undefined; + var deferredGlobalClassAccessorDecoratorTargetType: GenericType | undefined; + var deferredGlobalClassAccessorDecoratorResultType: GenericType | undefined; + var deferredGlobalClassFieldDecoratorContextType: GenericType | undefined; + + var allPotentiallyUnusedIdentifiers = new Map(); // key is file name + + var flowLoopStart = 0; + var flowLoopCount = 0; + var sharedFlowCount = 0; + var flowAnalysisDisabled = false; + var flowInvocationCount = 0; + var lastFlowNode: FlowNode | undefined; + var lastFlowNodeReachable: boolean; + var flowTypeCache: Type[] | undefined; + + var contextualTypeNodes: Node[] = []; + var contextualTypes: (Type | undefined)[] = []; + var contextualIsCache: boolean[] = []; + var contextualTypeCount = 0; + + var inferenceContextNodes: Node[] = []; + var inferenceContexts: (InferenceContext | undefined)[] = []; + var inferenceContextCount = 0; + + var emptyStringType = getStringLiteralType(""); + var zeroType = getNumberLiteralType(0); + var zeroBigIntType = getBigIntLiteralType({ negative: false, base10Value: "0" }); + + var resolutionTargets: TypeSystemEntity[] = []; + var resolutionResults: boolean[] = []; + var resolutionPropertyNames: TypeSystemPropertyName[] = []; + var resolutionStart = 0; + var inVarianceComputation = false; + + var suggestionCount = 0; + var maximumSuggestionCount = 10; + var mergedSymbols: Symbol[] = []; + var symbolLinks: SymbolLinks[] = []; + var nodeLinks: NodeLinks[] = []; + var flowLoopCaches: Map[] = []; + var flowLoopNodes: FlowNode[] = []; + var flowLoopKeys: string[] = []; + var flowLoopTypes: Type[][] = []; + var sharedFlowNodes: FlowNode[] = []; + var sharedFlowTypes: FlowType[] = []; + var flowNodeReachable: (boolean | undefined)[] = []; + var flowNodePostSuper: (boolean | undefined)[] = []; + var potentialThisCollisions: Node[] = []; + var potentialNewTargetCollisions: Node[] = []; + var potentialWeakMapSetCollisions: Node[] = []; + var potentialReflectCollisions: Node[] = []; + var potentialUnusedRenamedBindingElementsInTypes: BindingElement[] = []; + var awaitedTypeStack: number[] = []; + var reverseMappedSourceStack: Type[] = []; + var reverseMappedTargetStack: Type[] = []; + var reverseExpandingFlags = ExpandingFlags.None; + + var diagnostics = createDiagnosticCollection(); + var suggestionDiagnostics = createDiagnosticCollection(); + + var typeofType = createTypeofType(); + + var _jsxNamespace: __String; + var _jsxFactoryEntity: EntityName | undefined; + + var subtypeRelation = new Map(); + var strictSubtypeRelation = new Map(); + var assignableRelation = new Map(); + var comparableRelation = new Map(); + var identityRelation = new Map(); + var enumRelation = new Map(); + + // Extensions suggested for path imports when module resolution is node16 or higher. + // The first element of each tuple is the extension a file has. + // The second element of each tuple is the extension that should be used in a path import. + // e.g. if we want to import file `foo.mts`, we should write `import {} from "./foo.mjs". + var suggestedExtensions: [string, string][] = [ + [".mts", ".mjs"], + [".ts", ".js"], + [".cts", ".cjs"], + [".mjs", ".mjs"], + [".js", ".js"], + [".cjs", ".cjs"], + [".tsx", compilerOptions.jsx === JsxEmit.Preserve ? ".jsx" : ".js"], + [".jsx", ".jsx"], + [".json", ".json"], + ]; + /* eslint-enable no-var */ + + initializeTypeChecker(); + + return checker; + + function isDefinitelyReferenceToGlobalSymbolObject(node: Node): boolean { + if (!isPropertyAccessExpression(node)) return false; + if (!isIdentifier(node.name)) return false; + if (!isPropertyAccessExpression(node.expression) && !isIdentifier(node.expression)) return false; + if (isIdentifier(node.expression)) { + // Exactly `Symbol.something` and `Symbol` either does not resolve or definitely resolves to the global Symbol + return idText(node.expression) === "Symbol" && getResolvedSymbol(node.expression) === (getGlobalSymbol("Symbol" as __String, SymbolFlags.Value | SymbolFlags.ExportValue, /*diagnostic*/ undefined) || unknownSymbol); + } + if (!isIdentifier(node.expression.expression)) return false; + // Exactly `globalThis.Symbol.something` and `globalThis` resolves to the global `globalThis` + return idText(node.expression.name) === "Symbol" && idText(node.expression.expression) === "globalThis" && getResolvedSymbol(node.expression.expression) === globalThisSymbol; + } + + function getCachedType(key: string | undefined) { + return key ? cachedTypes.get(key) : undefined; + } + + function setCachedType(key: string | undefined, type: Type) { + if (key) cachedTypes.set(key, type); + return type; + } + + function getJsxNamespace(location: Node | undefined): __String { + if (location) { + const file = getSourceFileOfNode(location); + if (file) { + if (isJsxOpeningFragment(location)) { + if (file.localJsxFragmentNamespace) { + return file.localJsxFragmentNamespace; + } + const jsxFragmentPragma = file.pragmas.get("jsxfrag"); + if (jsxFragmentPragma) { + const chosenPragma = isArray(jsxFragmentPragma) ? jsxFragmentPragma[0] : jsxFragmentPragma; + file.localJsxFragmentFactory = parseIsolatedEntityName(chosenPragma.arguments.factory, languageVersion); + visitNode(file.localJsxFragmentFactory, markAsSynthetic, isEntityName); + if (file.localJsxFragmentFactory) { + return file.localJsxFragmentNamespace = getFirstIdentifier(file.localJsxFragmentFactory).escapedText; + } + } + const entity = getJsxFragmentFactoryEntity(location); + if (entity) { + file.localJsxFragmentFactory = entity; + return file.localJsxFragmentNamespace = getFirstIdentifier(entity).escapedText; + } + } + else { + const localJsxNamespace = getLocalJsxNamespace(file); + if (localJsxNamespace) { + return file.localJsxNamespace = localJsxNamespace; + } + } + } + } + if (!_jsxNamespace) { + _jsxNamespace = "React" as __String; + if (compilerOptions.jsxFactory) { + _jsxFactoryEntity = parseIsolatedEntityName(compilerOptions.jsxFactory, languageVersion); + visitNode(_jsxFactoryEntity, markAsSynthetic); + if (_jsxFactoryEntity) { + _jsxNamespace = getFirstIdentifier(_jsxFactoryEntity).escapedText; + } + } + else if (compilerOptions.reactNamespace) { + _jsxNamespace = escapeLeadingUnderscores(compilerOptions.reactNamespace); + } + } + if (!_jsxFactoryEntity) { + _jsxFactoryEntity = factory.createQualifiedName(factory.createIdentifier(unescapeLeadingUnderscores(_jsxNamespace)), "createElement"); + } + return _jsxNamespace; + } + + function getLocalJsxNamespace(file: SourceFile): __String | undefined { + if (file.localJsxNamespace) { + return file.localJsxNamespace; + } + const jsxPragma = file.pragmas.get("jsx"); + if (jsxPragma) { + const chosenPragma = isArray(jsxPragma) ? jsxPragma[0] : jsxPragma; + file.localJsxFactory = parseIsolatedEntityName(chosenPragma.arguments.factory, languageVersion); + visitNode(file.localJsxFactory, markAsSynthetic, isEntityName); + if (file.localJsxFactory) { + return file.localJsxNamespace = getFirstIdentifier(file.localJsxFactory).escapedText; + } + } + } + + function markAsSynthetic(node: T): VisitResult { + setTextRangePosEnd(node, -1, -1); + return visitEachChildWorker(node, markAsSynthetic, /*context*/ undefined); + } + + function getEmitResolver(sourceFile: SourceFile, cancellationToken: CancellationToken, skipDiagnostics?: boolean) { + // Ensure we have all the type information in place for this file so that all the + // emitter questions of this resolver will return the right information. + if (!skipDiagnostics) getDiagnostics(sourceFile, cancellationToken); + return emitResolver; + } + + function lookupOrIssueError(location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + const diagnostic = location + ? createDiagnosticForNode(location, message, ...args) + : createCompilerDiagnostic(message, ...args); + const existing = diagnostics.lookup(diagnostic); + if (existing) { + return existing; + } + else { + diagnostics.add(diagnostic); + return diagnostic; + } + } + + function errorSkippedOn(key: keyof CompilerOptions, location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + const diagnostic = error(location, message, ...args); + diagnostic.skippedOn = key; + return diagnostic; + } + + function createError(location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + return location + ? createDiagnosticForNode(location, message, ...args) + : createCompilerDiagnostic(message, ...args); + } + + function error(location: Node | undefined, message: DiagnosticMessage, ...args: DiagnosticArguments): Diagnostic { + const diagnostic = createError(location, message, ...args); + diagnostics.add(diagnostic); + return diagnostic; + } + + function addErrorOrSuggestion(isError: boolean, diagnostic: Diagnostic) { + if (isError) { + diagnostics.add(diagnostic); + } + else { + suggestionDiagnostics.add({ ...diagnostic, category: DiagnosticCategory.Suggestion }); + } + } + function errorOrSuggestion(isError: boolean, location: Node, message: DiagnosticMessage | DiagnosticMessageChain, ...args: DiagnosticArguments): void { + // Pseudo-synthesized input node + if (location.pos < 0 || location.end < 0) { + if (!isError) { + return; // Drop suggestions (we have no span to suggest on) + } + // Issue errors globally + const file = getSourceFileOfNode(location); + addErrorOrSuggestion(isError, "message" in message ? createFileDiagnostic(file, 0, 0, message, ...args) : createDiagnosticForFileFromMessageChain(file, message)); // eslint-disable-line local/no-in-operator + return; + } + addErrorOrSuggestion(isError, "message" in message ? createDiagnosticForNode(location, message, ...args) : createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(location), location, message)); // eslint-disable-line local/no-in-operator + } + + function errorAndMaybeSuggestAwait( + location: Node, + maybeMissingAwait: boolean, + message: DiagnosticMessage, + ...args: DiagnosticArguments + ): Diagnostic { + const diagnostic = error(location, message, ...args); + if (maybeMissingAwait) { + const related = createDiagnosticForNode(location, Diagnostics.Did_you_forget_to_use_await); + addRelatedInfo(diagnostic, related); + } + return diagnostic; + } + + function addDeprecatedSuggestionWorker(declarations: Node | Node[], diagnostic: DiagnosticWithLocation) { + const deprecatedTag = Array.isArray(declarations) ? forEach(declarations, getJSDocDeprecatedTag) : getJSDocDeprecatedTag(declarations); + if (deprecatedTag) { + addRelatedInfo( + diagnostic, + createDiagnosticForNode(deprecatedTag, Diagnostics.The_declaration_was_marked_as_deprecated_here), + ); + } + // We call `addRelatedInfo()` before adding the diagnostic to prevent duplicates. + suggestionDiagnostics.add(diagnostic); + return diagnostic; + } + + function isDeprecatedSymbol(symbol: Symbol) { + const parentSymbol = getParentOfSymbol(symbol); + if (parentSymbol && length(symbol.declarations) > 1) { + return parentSymbol.flags & SymbolFlags.Interface ? some(symbol.declarations, isDeprecatedDeclaration) : every(symbol.declarations, isDeprecatedDeclaration); + } + return !!symbol.valueDeclaration && isDeprecatedDeclaration(symbol.valueDeclaration) + || length(symbol.declarations) && every(symbol.declarations, isDeprecatedDeclaration); + } + + function isDeprecatedDeclaration(declaration: Declaration) { + return !!(getCombinedNodeFlagsCached(declaration) & NodeFlags.Deprecated); + } + + function addDeprecatedSuggestion(location: Node, declarations: Node[], deprecatedEntity: string) { + const diagnostic = createDiagnosticForNode(location, Diagnostics._0_is_deprecated, deprecatedEntity); + return addDeprecatedSuggestionWorker(declarations, diagnostic); + } + + function addDeprecatedSuggestionWithSignature(location: Node, declaration: Node, deprecatedEntity: string | undefined, signatureString: string) { + const diagnostic = deprecatedEntity + ? createDiagnosticForNode(location, Diagnostics.The_signature_0_of_1_is_deprecated, signatureString, deprecatedEntity) + : createDiagnosticForNode(location, Diagnostics._0_is_deprecated, signatureString); + return addDeprecatedSuggestionWorker(declaration, diagnostic); + } + + function createSymbol(flags: SymbolFlags, name: __String, checkFlags?: CheckFlags) { + symbolCount++; + const symbol = new Symbol(flags | SymbolFlags.Transient, name) as TransientSymbol; + symbol.links = new SymbolLinks() as TransientSymbolLinks; + symbol.links.checkFlags = checkFlags || CheckFlags.None; + return symbol; + } + + function createParameter(name: __String, type: Type) { + const symbol = createSymbol(SymbolFlags.FunctionScopedVariable, name); + symbol.links.type = type; + return symbol; + } + + function createProperty(name: __String, type: Type) { + const symbol = createSymbol(SymbolFlags.Property, name); + symbol.links.type = type; + return symbol; + } + + function getExcludedSymbolFlags(flags: SymbolFlags): SymbolFlags { + let result: SymbolFlags = 0; + if (flags & SymbolFlags.BlockScopedVariable) result |= SymbolFlags.BlockScopedVariableExcludes; + if (flags & SymbolFlags.FunctionScopedVariable) result |= SymbolFlags.FunctionScopedVariableExcludes; + if (flags & SymbolFlags.Property) result |= SymbolFlags.PropertyExcludes; + if (flags & SymbolFlags.EnumMember) result |= SymbolFlags.EnumMemberExcludes; + if (flags & SymbolFlags.Function) result |= SymbolFlags.FunctionExcludes; + if (flags & SymbolFlags.Class) result |= SymbolFlags.ClassExcludes; + if (flags & SymbolFlags.Interface) result |= SymbolFlags.InterfaceExcludes; + if (flags & SymbolFlags.RegularEnum) result |= SymbolFlags.RegularEnumExcludes; + if (flags & SymbolFlags.ConstEnum) result |= SymbolFlags.ConstEnumExcludes; + if (flags & SymbolFlags.ValueModule) result |= SymbolFlags.ValueModuleExcludes; + if (flags & SymbolFlags.Method) result |= SymbolFlags.MethodExcludes; + if (flags & SymbolFlags.GetAccessor) result |= SymbolFlags.GetAccessorExcludes; + if (flags & SymbolFlags.SetAccessor) result |= SymbolFlags.SetAccessorExcludes; + if (flags & SymbolFlags.TypeParameter) result |= SymbolFlags.TypeParameterExcludes; + if (flags & SymbolFlags.TypeAlias) result |= SymbolFlags.TypeAliasExcludes; + if (flags & SymbolFlags.Alias) result |= SymbolFlags.AliasExcludes; + return result; + } + + function recordMergedSymbol(target: Symbol, source: Symbol) { + if (!source.mergeId) { + source.mergeId = nextMergeId; + nextMergeId++; + } + mergedSymbols[source.mergeId] = target; + } + + function cloneSymbol(symbol: Symbol): TransientSymbol { + const result = createSymbol(symbol.flags, symbol.escapedName); + result.declarations = symbol.declarations ? symbol.declarations.slice() : []; + result.parent = symbol.parent; + if (symbol.valueDeclaration) result.valueDeclaration = symbol.valueDeclaration; + if (symbol.constEnumOnlyModule) result.constEnumOnlyModule = true; + if (symbol.members) result.members = new Map(symbol.members); + if (symbol.exports) result.exports = new Map(symbol.exports); + recordMergedSymbol(result, symbol); + return result; + } + + /** + * Note: if target is transient, then it is mutable, and mergeSymbol with both mutate and return it. + * If target is not transient, mergeSymbol will produce a transient clone, mutate that and return it. + */ + function mergeSymbol(target: Symbol, source: Symbol, unidirectional = false): Symbol { + if ( + !(target.flags & getExcludedSymbolFlags(source.flags)) || + (source.flags | target.flags) & SymbolFlags.Assignment + ) { + if (source === target) { + // This can happen when an export assigned namespace exports something also erroneously exported at the top level + // See `declarationFileNoCrashOnExtraExportModifier` for an example + return target; + } + if (!(target.flags & SymbolFlags.Transient)) { + const resolvedTarget = resolveSymbol(target); + if (resolvedTarget === unknownSymbol) { + return source; + } + if ( + !(resolvedTarget.flags & getExcludedSymbolFlags(source.flags)) || + (source.flags | resolvedTarget.flags) & SymbolFlags.Assignment + ) { + target = cloneSymbol(resolvedTarget); + } + else { + reportMergeSymbolError(target, source); + return source; + } + } + // Javascript static-property-assignment declarations always merge, even though they are also values + if (source.flags & SymbolFlags.ValueModule && target.flags & SymbolFlags.ValueModule && target.constEnumOnlyModule && !source.constEnumOnlyModule) { + // reset flag when merging instantiated module into value module that has only const enums + target.constEnumOnlyModule = false; + } + target.flags |= source.flags; + if (source.valueDeclaration) { + setValueDeclaration(target, source.valueDeclaration); + } + addRange(target.declarations, source.declarations); + if (source.members) { + if (!target.members) target.members = createSymbolTable(); + mergeSymbolTable(target.members, source.members, unidirectional); + } + if (source.exports) { + if (!target.exports) target.exports = createSymbolTable(); + mergeSymbolTable(target.exports, source.exports, unidirectional); + } + if (!unidirectional) { + recordMergedSymbol(target, source); + } + } + else if (target.flags & SymbolFlags.NamespaceModule) { + // Do not report an error when merging `var globalThis` with the built-in `globalThis`, + // as we will already report a "Declaration name conflicts..." error, and this error + // won't make much sense. + if (target !== globalThisSymbol) { + error( + source.declarations && getNameOfDeclaration(source.declarations[0]), + Diagnostics.Cannot_augment_module_0_with_value_exports_because_it_resolves_to_a_non_module_entity, + symbolToString(target), + ); + } + } + else { + reportMergeSymbolError(target, source); + } + return target; + + function reportMergeSymbolError(target: Symbol, source: Symbol) { + const isEitherEnum = !!(target.flags & SymbolFlags.Enum || source.flags & SymbolFlags.Enum); + const isEitherBlockScoped = !!(target.flags & SymbolFlags.BlockScopedVariable || source.flags & SymbolFlags.BlockScopedVariable); + const message = isEitherEnum ? Diagnostics.Enum_declarations_can_only_merge_with_namespace_or_other_enum_declarations + : isEitherBlockScoped ? Diagnostics.Cannot_redeclare_block_scoped_variable_0 + : Diagnostics.Duplicate_identifier_0; + const sourceSymbolFile = source.declarations && getSourceFileOfNode(source.declarations[0]); + const targetSymbolFile = target.declarations && getSourceFileOfNode(target.declarations[0]); + + const isSourcePlainJs = isPlainJsFile(sourceSymbolFile, compilerOptions.checkJs); + const isTargetPlainJs = isPlainJsFile(targetSymbolFile, compilerOptions.checkJs); + const symbolName = symbolToString(source); + + // Collect top-level duplicate identifier errors into one mapping, so we can then merge their diagnostics if there are a bunch + if (sourceSymbolFile && targetSymbolFile && amalgamatedDuplicates && !isEitherEnum && sourceSymbolFile !== targetSymbolFile) { + const firstFile = comparePaths(sourceSymbolFile.path, targetSymbolFile.path) === Comparison.LessThan ? sourceSymbolFile : targetSymbolFile; + const secondFile = firstFile === sourceSymbolFile ? targetSymbolFile : sourceSymbolFile; + const filesDuplicates = getOrUpdate(amalgamatedDuplicates, `${firstFile.path}|${secondFile.path}`, (): DuplicateInfoForFiles => ({ firstFile, secondFile, conflictingSymbols: new Map() })); + const conflictingSymbolInfo = getOrUpdate(filesDuplicates.conflictingSymbols, symbolName, (): DuplicateInfoForSymbol => ({ isBlockScoped: isEitherBlockScoped, firstFileLocations: [], secondFileLocations: [] })); + if (!isSourcePlainJs) addDuplicateLocations(conflictingSymbolInfo.firstFileLocations, source); + if (!isTargetPlainJs) addDuplicateLocations(conflictingSymbolInfo.secondFileLocations, target); + } + else { + if (!isSourcePlainJs) addDuplicateDeclarationErrorsForSymbols(source, message, symbolName, target); + if (!isTargetPlainJs) addDuplicateDeclarationErrorsForSymbols(target, message, symbolName, source); + } + } + + function addDuplicateLocations(locs: Declaration[], symbol: Symbol): void { + if (symbol.declarations) { + for (const decl of symbol.declarations) { + pushIfUnique(locs, decl); + } + } + } + } + + function addDuplicateDeclarationErrorsForSymbols(target: Symbol, message: DiagnosticMessage, symbolName: string, source: Symbol) { + forEach(target.declarations, node => { + addDuplicateDeclarationError(node, message, symbolName, source.declarations); + }); + } + + function addDuplicateDeclarationError(node: Declaration, message: DiagnosticMessage, symbolName: string, relatedNodes: readonly Declaration[] | undefined) { + const errorNode = (getExpandoInitializer(node, /*isPrototypeAssignment*/ false) ? getNameOfExpando(node) : getNameOfDeclaration(node)) || node; + const err = lookupOrIssueError(errorNode, message, symbolName); + for (const relatedNode of relatedNodes || emptyArray) { + const adjustedNode = (getExpandoInitializer(relatedNode, /*isPrototypeAssignment*/ false) ? getNameOfExpando(relatedNode) : getNameOfDeclaration(relatedNode)) || relatedNode; + if (adjustedNode === errorNode) continue; + err.relatedInformation = err.relatedInformation || []; + const leadingMessage = createDiagnosticForNode(adjustedNode, Diagnostics._0_was_also_declared_here, symbolName); + const followOnMessage = createDiagnosticForNode(adjustedNode, Diagnostics.and_here); + if (length(err.relatedInformation) >= 5 || some(err.relatedInformation, r => compareDiagnostics(r, followOnMessage) === Comparison.EqualTo || compareDiagnostics(r, leadingMessage) === Comparison.EqualTo)) continue; + addRelatedInfo(err, !length(err.relatedInformation) ? leadingMessage : followOnMessage); + } + } + + function combineSymbolTables(first: SymbolTable | undefined, second: SymbolTable | undefined): SymbolTable | undefined { + if (!first?.size) return second; + if (!second?.size) return first; + const combined = createSymbolTable(); + mergeSymbolTable(combined, first); + mergeSymbolTable(combined, second); + return combined; + } + + function mergeSymbolTable(target: SymbolTable, source: SymbolTable, unidirectional = false) { + source.forEach((sourceSymbol, id) => { + const targetSymbol = target.get(id); + target.set(id, targetSymbol ? mergeSymbol(targetSymbol, sourceSymbol, unidirectional) : getMergedSymbol(sourceSymbol)); + }); + } + + function mergeModuleAugmentation(moduleName: StringLiteral | Identifier): void { + const moduleAugmentation = moduleName.parent as ModuleDeclaration; + if (moduleAugmentation.symbol.declarations?.[0] !== moduleAugmentation) { + // this is a combined symbol for multiple augmentations within the same file. + // its symbol already has accumulated information for all declarations + // so we need to add it just once - do the work only for first declaration + Debug.assert(moduleAugmentation.symbol.declarations!.length > 1); + return; + } + + if (isGlobalScopeAugmentation(moduleAugmentation)) { + mergeSymbolTable(globals, moduleAugmentation.symbol.exports!); + } + else { + // find a module that about to be augmented + // do not validate names of augmentations that are defined in ambient context + const moduleNotFoundError = !(moduleName.parent.parent.flags & NodeFlags.Ambient) + ? Diagnostics.Invalid_module_name_in_augmentation_module_0_cannot_be_found + : undefined; + let mainModule = resolveExternalModuleNameWorker(moduleName, moduleName, moduleNotFoundError, /*isForAugmentation*/ true); + if (!mainModule) { + return; + } + // obtain item referenced by 'export=' + mainModule = resolveExternalModuleSymbol(mainModule); + if (mainModule.flags & SymbolFlags.Namespace) { + // If we're merging an augmentation to a pattern ambient module, we want to + // perform the merge unidirectionally from the augmentation ('a.foo') to + // the pattern ('*.foo'), so that 'getMergedSymbol()' on a.foo gives you + // all the exports both from the pattern and from the augmentation, but + // 'getMergedSymbol()' on *.foo only gives you exports from *.foo. + if (some(patternAmbientModules, module => mainModule === module.symbol)) { + const merged = mergeSymbol(moduleAugmentation.symbol, mainModule, /*unidirectional*/ true); + if (!patternAmbientModuleAugmentations) { + patternAmbientModuleAugmentations = new Map(); + } + // moduleName will be a StringLiteral since this is not `declare global`. + patternAmbientModuleAugmentations.set((moduleName as StringLiteral).text, merged); + } + else { + if (mainModule.exports?.get(InternalSymbolName.ExportStar) && moduleAugmentation.symbol.exports?.size) { + // We may need to merge the module augmentation's exports into the target symbols of the resolved exports + const resolvedExports = getResolvedMembersOrExportsOfSymbol(mainModule, MembersOrExportsResolutionKind.resolvedExports); + for (const [key, value] of arrayFrom(moduleAugmentation.symbol.exports.entries())) { + if (resolvedExports.has(key) && !mainModule.exports.has(key)) { + mergeSymbol(resolvedExports.get(key)!, value); + } + } + } + mergeSymbol(mainModule, moduleAugmentation.symbol); + } + } + else { + // moduleName will be a StringLiteral since this is not `declare global`. + error(moduleName, Diagnostics.Cannot_augment_module_0_because_it_resolves_to_a_non_module_entity, (moduleName as StringLiteral).text); + } + } + } + + function addUndefinedToGlobalsOrErrorOnRedeclaration() { + const name = undefinedSymbol.escapedName; + const targetSymbol = globals.get(name); + if (targetSymbol) { + forEach(targetSymbol.declarations, declaration => { + // checkTypeNameIsReserved will have added better diagnostics for type declarations. + if (!isTypeDeclaration(declaration)) { + diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Declaration_name_conflicts_with_built_in_global_identifier_0, unescapeLeadingUnderscores(name))); + } + }); + } + else { + globals.set(name, undefinedSymbol); + } + } + + function getSymbolLinks(symbol: Symbol): SymbolLinks { + if (symbol.flags & SymbolFlags.Transient) return (symbol as TransientSymbol).links; + const id = getSymbolId(symbol); + return symbolLinks[id] ??= new SymbolLinks(); + } + + function getNodeLinks(node: Node): NodeLinks { + const nodeId = getNodeId(node); + return nodeLinks[nodeId] || (nodeLinks[nodeId] = new (NodeLinks as any)()); + } + + function getSymbol(symbols: SymbolTable, name: __String, meaning: SymbolFlags): Symbol | undefined { + if (meaning) { + const symbol = getMergedSymbol(symbols.get(name)); + if (symbol) { + if (symbol.flags & meaning) { + return symbol; + } + if (symbol.flags & SymbolFlags.Alias) { + const targetFlags = getSymbolFlags(symbol); + // `targetFlags` will be `SymbolFlags.All` if an error occurred in alias resolution; this avoids cascading errors + if (targetFlags & meaning) { + return symbol; + } + } + } + } + // return undefined if we can't find a symbol. + } + + /** + * Get symbols that represent parameter-property-declaration as parameter and as property declaration + * @param parameter a parameterDeclaration node + * @param parameterName a name of the parameter to get the symbols for. + * @return a tuple of two symbols + */ + function getSymbolsOfParameterPropertyDeclaration(parameter: ParameterPropertyDeclaration, parameterName: __String): [Symbol, Symbol] { + const constructorDeclaration = parameter.parent; + const classDeclaration = parameter.parent.parent; + + const parameterSymbol = getSymbol(constructorDeclaration.locals!, parameterName, SymbolFlags.Value); + const propertySymbol = getSymbol(getMembersOfSymbol(classDeclaration.symbol), parameterName, SymbolFlags.Value); + + if (parameterSymbol && propertySymbol) { + return [parameterSymbol, propertySymbol]; + } + + return Debug.fail("There should exist two symbols, one as property declaration and one as parameter declaration"); + } + + function isBlockScopedNameDeclaredBeforeUse(declaration: Declaration, usage: Node): boolean { + const declarationFile = getSourceFileOfNode(declaration); + const useFile = getSourceFileOfNode(usage); + const declContainer = getEnclosingBlockScopeContainer(declaration); + if (declarationFile !== useFile) { + if ( + (moduleKind && (declarationFile.externalModuleIndicator || useFile.externalModuleIndicator)) || + (!compilerOptions.outFile) || + isInTypeQuery(usage) || + declaration.flags & NodeFlags.Ambient + ) { + // nodes are in different files and order cannot be determined + return true; + } + // declaration is after usage + // can be legal if usage is deferred (i.e. inside function or in initializer of instance property) + if (isUsedInFunctionOrInstanceProperty(usage, declaration)) { + return true; + } + const sourceFiles = host.getSourceFiles(); + return sourceFiles.indexOf(declarationFile) <= sourceFiles.indexOf(useFile); + } + + // deferred usage in a type context is always OK regardless of the usage position: + if (!!(usage.flags & NodeFlags.JSDoc) || isInTypeQuery(usage) || isInAmbientOrTypeNode(usage)) { + return true; + } + + if (declaration.pos <= usage.pos && !(isPropertyDeclaration(declaration) && isThisProperty(usage.parent) && !declaration.initializer && !declaration.exclamationToken)) { + // declaration is before usage + if (declaration.kind === SyntaxKind.BindingElement) { + // still might be illegal if declaration and usage are both binding elements (eg var [a = b, b = b] = [1, 2]) + const errorBindingElement = getAncestor(usage, SyntaxKind.BindingElement) as BindingElement; + if (errorBindingElement) { + return findAncestor(errorBindingElement, isBindingElement) !== findAncestor(declaration, isBindingElement) || + declaration.pos < errorBindingElement.pos; + } + // or it might be illegal if usage happens before parent variable is declared (eg var [a] = a) + return isBlockScopedNameDeclaredBeforeUse(getAncestor(declaration, SyntaxKind.VariableDeclaration) as Declaration, usage); + } + else if (declaration.kind === SyntaxKind.VariableDeclaration) { + // still might be illegal if usage is in the initializer of the variable declaration (eg var a = a) + return !isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration as VariableDeclaration, usage); + } + else if (isClassLike(declaration)) { + // still might be illegal if the usage is within a computed property name in the class (eg class A { static p = "a"; [A.p]() {} }) + // or when used within a decorator in the class (e.g. `@dec(A.x) class A { static x = "x" }`), + // except when used in a function that is not an IIFE (e.g., `@dec(() => A.x) class A { ... }`) + const container = findAncestor(usage, n => + n === declaration ? "quit" : + isComputedPropertyName(n) ? n.parent.parent === declaration : + !legacyDecorators && isDecorator(n) && (n.parent === declaration || + isMethodDeclaration(n.parent) && n.parent.parent === declaration || + isGetOrSetAccessorDeclaration(n.parent) && n.parent.parent === declaration || + isPropertyDeclaration(n.parent) && n.parent.parent === declaration || + isParameter(n.parent) && n.parent.parent.parent === declaration)); + if (!container) { + return true; + } + if (!legacyDecorators && isDecorator(container)) { + return !!findAncestor(usage, n => n === container ? "quit" : isFunctionLike(n) && !getImmediatelyInvokedFunctionExpression(n)); + } + return false; + } + else if (isPropertyDeclaration(declaration)) { + // still might be illegal if a self-referencing property initializer (eg private x = this.x) + return !isPropertyImmediatelyReferencedWithinDeclaration(declaration, usage, /*stopAtAnyPropertyDeclaration*/ false); + } + else if (isParameterPropertyDeclaration(declaration, declaration.parent)) { + // foo = this.bar is illegal in emitStandardClassFields when bar is a parameter property + return !(emitStandardClassFields + && getContainingClass(declaration) === getContainingClass(usage) + && isUsedInFunctionOrInstanceProperty(usage, declaration)); + } + return true; + } + + // declaration is after usage, but it can still be legal if usage is deferred: + // 1. inside an export specifier + // 2. inside a function + // 3. inside an instance property initializer, a reference to a non-instance property + // (except when emitStandardClassFields: true and the reference is to a parameter property) + // 4. inside a static property initializer, a reference to a static method in the same class + // 5. inside a TS export= declaration (since we will move the export statement during emit to avoid TDZ) + if (usage.parent.kind === SyntaxKind.ExportSpecifier || (usage.parent.kind === SyntaxKind.ExportAssignment && (usage.parent as ExportAssignment).isExportEquals)) { + // export specifiers do not use the variable, they only make it available for use + return true; + } + // When resolving symbols for exports, the `usage` location passed in can be the export site directly + if (usage.kind === SyntaxKind.ExportAssignment && (usage as ExportAssignment).isExportEquals) { + return true; + } + + if (isUsedInFunctionOrInstanceProperty(usage, declaration)) { + if ( + emitStandardClassFields + && getContainingClass(declaration) + && (isPropertyDeclaration(declaration) || isParameterPropertyDeclaration(declaration, declaration.parent)) + ) { + return !isPropertyImmediatelyReferencedWithinDeclaration(declaration, usage, /*stopAtAnyPropertyDeclaration*/ true); + } + else { + return true; + } + } + return false; + + function isImmediatelyUsedInInitializerOfBlockScopedVariable(declaration: VariableDeclaration, usage: Node): boolean { + switch (declaration.parent.parent.kind) { + case SyntaxKind.VariableStatement: + case SyntaxKind.ForStatement: + case SyntaxKind.ForOfStatement: + // variable statement/for/for-of statement case, + // use site should not be inside variable declaration (initializer of declaration or binding element) + if (isSameScopeDescendentOf(usage, declaration, declContainer)) { + return true; + } + break; + } + + // ForIn/ForOf case - use site should not be used in expression part + const grandparent = declaration.parent.parent; + return isForInOrOfStatement(grandparent) && isSameScopeDescendentOf(usage, grandparent.expression, declContainer); + } + + function isUsedInFunctionOrInstanceProperty(usage: Node, declaration: Node): boolean { + return !!findAncestor(usage, current => { + if (current === declContainer) { + return "quit"; + } + if (isFunctionLike(current)) { + return true; + } + if (isClassStaticBlockDeclaration(current)) { + return declaration.pos < usage.pos; + } + + const propertyDeclaration = tryCast(current.parent, isPropertyDeclaration); + if (propertyDeclaration) { + const initializerOfProperty = propertyDeclaration.initializer === current; + if (initializerOfProperty) { + if (isStatic(current.parent)) { + if (declaration.kind === SyntaxKind.MethodDeclaration) { + return true; + } + if (isPropertyDeclaration(declaration) && getContainingClass(usage) === getContainingClass(declaration)) { + const propName = declaration.name; + if (isIdentifier(propName) || isPrivateIdentifier(propName)) { + const type = getTypeOfSymbol(getSymbolOfDeclaration(declaration)); + const staticBlocks = filter(declaration.parent.members, isClassStaticBlockDeclaration); + if (isPropertyInitializedInStaticBlocks(propName, type, staticBlocks, declaration.parent.pos, current.pos)) { + return true; + } + } + } + } + else { + const isDeclarationInstanceProperty = declaration.kind === SyntaxKind.PropertyDeclaration && !isStatic(declaration); + if (!isDeclarationInstanceProperty || getContainingClass(usage) !== getContainingClass(declaration)) { + return true; + } + } + } + } + return false; + }); + } + + /** stopAtAnyPropertyDeclaration is used for detecting ES-standard class field use-before-def errors */ + function isPropertyImmediatelyReferencedWithinDeclaration(declaration: PropertyDeclaration | ParameterPropertyDeclaration, usage: Node, stopAtAnyPropertyDeclaration: boolean) { + // always legal if usage is after declaration + if (usage.end > declaration.end) { + return false; + } + + // still might be legal if usage is deferred (e.g. x: any = () => this.x) + // otherwise illegal if immediately referenced within the declaration (e.g. x: any = this.x) + const ancestorChangingReferenceScope = findAncestor(usage, (node: Node) => { + if (node === declaration) { + return "quit"; + } + + switch (node.kind) { + case SyntaxKind.ArrowFunction: + return true; + case SyntaxKind.PropertyDeclaration: + // even when stopping at any property declaration, they need to come from the same class + return stopAtAnyPropertyDeclaration && + (isPropertyDeclaration(declaration) && node.parent === declaration.parent + || isParameterPropertyDeclaration(declaration, declaration.parent) && node.parent === declaration.parent.parent) + ? "quit" : true; + case SyntaxKind.Block: + switch (node.parent.kind) { + case SyntaxKind.GetAccessor: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.SetAccessor: + return true; + default: + return false; + } + default: + return false; + } + }); + + return ancestorChangingReferenceScope === undefined; + } + } + + function getRequiresScopeChangeCache(node: FunctionLikeDeclaration) { + return getNodeLinks(node).declarationRequiresScopeChange; + } + function setRequiresScopeChangeCache(node: FunctionLikeDeclaration, value: boolean) { + getNodeLinks(node).declarationRequiresScopeChange = value; + } + // The invalid initializer error is needed in two situation: + // 1. When result is undefined, after checking for a missing "this." + // 2. When result is defined + function checkAndReportErrorForInvalidInitializer(errorLocation: Node | undefined, name: __String, propertyWithInvalidInitializer: PropertyDeclaration, result: Symbol | undefined) { + if (!emitStandardClassFields) { + if (errorLocation && !result && checkAndReportErrorForMissingPrefix(errorLocation, name, name)) { + return true; + } + // We have a match, but the reference occurred within a property initializer and the identifier also binds + // to a local variable in the constructor where the code will be emitted. Note that this is actually allowed + // with emitStandardClassFields because the scope semantics are different. + error( + errorLocation, + errorLocation && propertyWithInvalidInitializer.type && textRangeContainsPositionInclusive(propertyWithInvalidInitializer.type, errorLocation.pos) + ? Diagnostics.Type_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor + : Diagnostics.Initializer_of_instance_member_variable_0_cannot_reference_identifier_1_declared_in_the_constructor, + declarationNameToString(propertyWithInvalidInitializer.name), + diagnosticName(name), + ); + return true; + } + return false; + } + function onFailedToResolveSymbol( + errorLocation: Node | undefined, + nameArg: __String | Identifier, + meaning: SymbolFlags, + nameNotFoundMessage: DiagnosticMessage, + ) { + const name = isString(nameArg) ? nameArg : (nameArg as Identifier).escapedText; + addLazyDiagnostic(() => { + if ( + !errorLocation || + errorLocation.parent.kind !== SyntaxKind.JSDocLink && + !checkAndReportErrorForMissingPrefix(errorLocation, name, nameArg) && + !checkAndReportErrorForExtendingInterface(errorLocation) && + !checkAndReportErrorForUsingTypeAsNamespace(errorLocation, name, meaning) && + !checkAndReportErrorForExportingPrimitiveType(errorLocation, name) && + !checkAndReportErrorForUsingNamespaceAsTypeOrValue(errorLocation, name, meaning) && + !checkAndReportErrorForUsingTypeAsValue(errorLocation, name, meaning) && + !checkAndReportErrorForUsingValueAsType(errorLocation, name, meaning) + ) { + let suggestion: Symbol | undefined; + let suggestedLib: string | undefined; + // Report missing lib first + if (nameArg) { + suggestedLib = getSuggestedLibForNonExistentName(nameArg); + if (suggestedLib) { + error(errorLocation, nameNotFoundMessage, diagnosticName(nameArg), suggestedLib); + } + } + // then spelling suggestions + if (!suggestedLib && suggestionCount < maximumSuggestionCount) { + suggestion = getSuggestedSymbolForNonexistentSymbol(errorLocation, name, meaning); + const isGlobalScopeAugmentationDeclaration = suggestion?.valueDeclaration && isAmbientModule(suggestion.valueDeclaration) && isGlobalScopeAugmentation(suggestion.valueDeclaration); + if (isGlobalScopeAugmentationDeclaration) { + suggestion = undefined; + } + if (suggestion) { + const suggestionName = symbolToString(suggestion); + const isUncheckedJS = isUncheckedJSSuggestion(errorLocation, suggestion, /*excludeClasses*/ false); + const message = meaning === SymbolFlags.Namespace || + nameArg && typeof nameArg !== "string" && nodeIsSynthesized(nameArg) ? + Diagnostics.Cannot_find_namespace_0_Did_you_mean_1 + : isUncheckedJS ? Diagnostics.Could_not_find_name_0_Did_you_mean_1 + : Diagnostics.Cannot_find_name_0_Did_you_mean_1; + const diagnostic = createError(errorLocation, message, diagnosticName(nameArg), suggestionName); + diagnostic.canonicalHead = getCanonicalDiagnostic(nameNotFoundMessage, diagnosticName(nameArg)); + addErrorOrSuggestion(!isUncheckedJS, diagnostic); + if (suggestion.valueDeclaration) { + addRelatedInfo( + diagnostic, + createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestionName), + ); + } + } + } + // And then fall back to unspecified "not found" + if (!suggestion && !suggestedLib && nameArg) { + error(errorLocation, nameNotFoundMessage, diagnosticName(nameArg)); + } + suggestionCount++; + } + }); + } + + function onSuccessfullyResolvedSymbol( + errorLocation: Node | undefined, + result: Symbol, + meaning: SymbolFlags, + lastLocation: Node | undefined, + associatedDeclarationForContainingInitializerOrBindingName: ParameterDeclaration | BindingElement | undefined, + withinDeferredContext: boolean, + ) { + addLazyDiagnostic(() => { + const name = result.escapedName; + const isInExternalModule = lastLocation && isSourceFile(lastLocation) && isExternalOrCommonJsModule(lastLocation); + // Only check for block-scoped variable if we have an error location and are looking for the + // name with variable meaning + // For example, + // declare module foo { + // interface bar {} + // } + // const foo/*1*/: foo/*2*/.bar; + // The foo at /*1*/ and /*2*/ will share same symbol with two meanings: + // block-scoped variable and namespace module. However, only when we + // try to resolve name in /*1*/ which is used in variable position, + // we want to check for block-scoped + if ( + errorLocation && + (meaning & SymbolFlags.BlockScopedVariable || + ((meaning & SymbolFlags.Class || meaning & SymbolFlags.Enum) && (meaning & SymbolFlags.Value) === SymbolFlags.Value)) + ) { + const exportOrLocalSymbol = getExportSymbolOfValueSymbolIfExported(result); + if (exportOrLocalSymbol.flags & SymbolFlags.BlockScopedVariable || exportOrLocalSymbol.flags & SymbolFlags.Class || exportOrLocalSymbol.flags & SymbolFlags.Enum) { + checkResolvedBlockScopedVariable(exportOrLocalSymbol, errorLocation); + } + } + + // If we're in an external module, we can't reference value symbols created from UMD export declarations + if (isInExternalModule && (meaning & SymbolFlags.Value) === SymbolFlags.Value && !(errorLocation!.flags & NodeFlags.JSDoc)) { + const merged = getMergedSymbol(result); + if (length(merged.declarations) && every(merged.declarations, d => isNamespaceExportDeclaration(d) || isSourceFile(d) && !!d.symbol.globalExports)) { + errorOrSuggestion(!compilerOptions.allowUmdGlobalAccess, errorLocation!, Diagnostics._0_refers_to_a_UMD_global_but_the_current_file_is_a_module_Consider_adding_an_import_instead, unescapeLeadingUnderscores(name)); + } + } + + // If we're in a parameter initializer or binding name, we can't reference the values of the parameter whose initializer we're within or parameters to the right + if (associatedDeclarationForContainingInitializerOrBindingName && !withinDeferredContext && (meaning & SymbolFlags.Value) === SymbolFlags.Value) { + const candidate = getMergedSymbol(getLateBoundSymbol(result)); + const root = getRootDeclaration(associatedDeclarationForContainingInitializerOrBindingName) as ParameterDeclaration; + // A parameter initializer or binding pattern initializer within a parameter cannot refer to itself + if (candidate === getSymbolOfDeclaration(associatedDeclarationForContainingInitializerOrBindingName)) { + error(errorLocation, Diagnostics.Parameter_0_cannot_reference_itself, declarationNameToString(associatedDeclarationForContainingInitializerOrBindingName.name)); + } + // And it cannot refer to any declarations which come after it + else if (candidate.valueDeclaration && candidate.valueDeclaration.pos > associatedDeclarationForContainingInitializerOrBindingName.pos && root.parent.locals && getSymbol(root.parent.locals, candidate.escapedName, meaning) === candidate) { + error(errorLocation, Diagnostics.Parameter_0_cannot_reference_identifier_1_declared_after_it, declarationNameToString(associatedDeclarationForContainingInitializerOrBindingName.name), declarationNameToString(errorLocation as Identifier)); + } + } + if (errorLocation && meaning & SymbolFlags.Value && result.flags & SymbolFlags.Alias && !(result.flags & SymbolFlags.Value) && !isValidTypeOnlyAliasUseSite(errorLocation)) { + const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(result, SymbolFlags.Value); + if (typeOnlyDeclaration) { + const message = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration || typeOnlyDeclaration.kind === SyntaxKind.NamespaceExport + ? Diagnostics._0_cannot_be_used_as_a_value_because_it_was_exported_using_export_type + : Diagnostics._0_cannot_be_used_as_a_value_because_it_was_imported_using_import_type; + const unescapedName = unescapeLeadingUnderscores(name); + addTypeOnlyDeclarationRelatedInfo( + error(errorLocation, message, unescapedName), + typeOnlyDeclaration, + unescapedName, + ); + } + } + + // Look at 'compilerOptions.isolatedModules' and not 'getIsolatedModules(...)' (which considers 'verbatimModuleSyntax') + // here because 'verbatimModuleSyntax' will already have an error for importing a type without 'import type'. + if (compilerOptions.isolatedModules && result && isInExternalModule && (meaning & SymbolFlags.Value) === SymbolFlags.Value) { + const isGlobal = getSymbol(globals, name, meaning) === result; + const nonValueSymbol = isGlobal && isSourceFile(lastLocation) && lastLocation.locals && getSymbol(lastLocation.locals, name, ~SymbolFlags.Value); + if (nonValueSymbol) { + const importDecl = nonValueSymbol.declarations?.find(d => d.kind === SyntaxKind.ImportSpecifier || d.kind === SyntaxKind.ImportClause || d.kind === SyntaxKind.NamespaceImport || d.kind === SyntaxKind.ImportEqualsDeclaration); + if (importDecl && !isTypeOnlyImportDeclaration(importDecl)) { + error(importDecl, Diagnostics.Import_0_conflicts_with_global_value_used_in_this_file_so_must_be_declared_with_a_type_only_import_when_isolatedModules_is_enabled, unescapeLeadingUnderscores(name)); + } + } + } + }); + } + + function addTypeOnlyDeclarationRelatedInfo(diagnostic: Diagnostic, typeOnlyDeclaration: TypeOnlyCompatibleAliasDeclaration | undefined, unescapedName: string) { + if (!typeOnlyDeclaration) return diagnostic; + return addRelatedInfo( + diagnostic, + createDiagnosticForNode( + typeOnlyDeclaration, + typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration || typeOnlyDeclaration.kind === SyntaxKind.NamespaceExport + ? Diagnostics._0_was_exported_here + : Diagnostics._0_was_imported_here, + unescapedName, + ), + ); + } + + function diagnosticName(nameArg: __String | Identifier | PrivateIdentifier) { + return isString(nameArg) ? unescapeLeadingUnderscores(nameArg as __String) : declarationNameToString(nameArg as Identifier); + } + + function checkAndReportErrorForMissingPrefix(errorLocation: Node, name: __String, nameArg: __String | Identifier): boolean { + if (!isIdentifier(errorLocation) || errorLocation.escapedText !== name || isTypeReferenceIdentifier(errorLocation) || isInTypeQuery(errorLocation)) { + return false; + } + + const container = getThisContainer(errorLocation, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + let location: Node = container; + while (location) { + if (isClassLike(location.parent)) { + const classSymbol = getSymbolOfDeclaration(location.parent); + if (!classSymbol) { + break; + } + + // Check to see if a static member exists. + const constructorType = getTypeOfSymbol(classSymbol); + if (getPropertyOfType(constructorType, name)) { + error(errorLocation, Diagnostics.Cannot_find_name_0_Did_you_mean_the_static_member_1_0, diagnosticName(nameArg), symbolToString(classSymbol)); + return true; + } + + // No static member is present. + // Check if we're in an instance method and look for a relevant instance member. + if (location === container && !isStatic(location)) { + const instanceType = (getDeclaredTypeOfSymbol(classSymbol) as InterfaceType).thisType!; // TODO: GH#18217 + if (getPropertyOfType(instanceType, name)) { + error(errorLocation, Diagnostics.Cannot_find_name_0_Did_you_mean_the_instance_member_this_0, diagnosticName(nameArg)); + return true; + } + } + } + + location = location.parent; + } + return false; + } + + function checkAndReportErrorForExtendingInterface(errorLocation: Node): boolean { + const expression = getEntityNameForExtendingInterface(errorLocation); + if (expression && resolveEntityName(expression, SymbolFlags.Interface, /*ignoreErrors*/ true)) { + error(errorLocation, Diagnostics.Cannot_extend_an_interface_0_Did_you_mean_implements, getTextOfNode(expression)); + return true; + } + return false; + } + /** + * Climbs up parents to an ExpressionWithTypeArguments, and returns its expression, + * but returns undefined if that expression is not an EntityNameExpression. + */ + function getEntityNameForExtendingInterface(node: Node): EntityNameExpression | undefined { + switch (node.kind) { + case SyntaxKind.Identifier: + case SyntaxKind.PropertyAccessExpression: + return node.parent ? getEntityNameForExtendingInterface(node.parent) : undefined; + case SyntaxKind.ExpressionWithTypeArguments: + if (isEntityNameExpression((node as ExpressionWithTypeArguments).expression)) { + return (node as ExpressionWithTypeArguments).expression as EntityNameExpression; + } + // falls through + default: + return undefined; + } + } + + function checkAndReportErrorForUsingTypeAsNamespace(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + const namespaceMeaning = SymbolFlags.Namespace | (isInJSFile(errorLocation) ? SymbolFlags.Value : 0); + if (meaning === namespaceMeaning) { + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Type & ~namespaceMeaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + const parent = errorLocation.parent; + if (symbol) { + if (isQualifiedName(parent)) { + Debug.assert(parent.left === errorLocation, "Should only be resolving left side of qualified name as a namespace"); + const propName = parent.right.escapedText; + const propType = getPropertyOfType(getDeclaredTypeOfSymbol(symbol), propName); + if (propType) { + error( + parent, + Diagnostics.Cannot_access_0_1_because_0_is_a_type_but_not_a_namespace_Did_you_mean_to_retrieve_the_type_of_the_property_1_in_0_with_0_1, + unescapeLeadingUnderscores(name), + unescapeLeadingUnderscores(propName), + ); + return true; + } + } + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_namespace_here, unescapeLeadingUnderscores(name)); + return true; + } + } + + return false; + } + + function checkAndReportErrorForUsingValueAsType(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + if (meaning & (SymbolFlags.Type & ~SymbolFlags.Namespace)) { + const symbol = resolveSymbol(resolveName(errorLocation, name, ~SymbolFlags.Type & SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + if (symbol && !(symbol.flags & SymbolFlags.Namespace)) { + error(errorLocation, Diagnostics._0_refers_to_a_value_but_is_being_used_as_a_type_here_Did_you_mean_typeof_0, unescapeLeadingUnderscores(name)); + return true; + } + } + return false; + } + + function isPrimitiveTypeName(name: __String) { + return name === "any" || name === "string" || name === "number" || name === "boolean" || name === "never" || name === "unknown"; + } + + function checkAndReportErrorForExportingPrimitiveType(errorLocation: Node, name: __String): boolean { + if (isPrimitiveTypeName(name) && errorLocation.parent.kind === SyntaxKind.ExportSpecifier) { + error(errorLocation, Diagnostics.Cannot_export_0_Only_local_declarations_can_be_exported_from_a_module, name as string); + return true; + } + return false; + } + + function checkAndReportErrorForUsingTypeAsValue(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + if (meaning & SymbolFlags.Value) { + if (isPrimitiveTypeName(name)) { + const grandparent = errorLocation.parent.parent; + if (grandparent && grandparent.parent && isHeritageClause(grandparent)) { + const heritageKind = grandparent.token; + const containerKind = grandparent.parent.kind; + if (containerKind === SyntaxKind.InterfaceDeclaration && heritageKind === SyntaxKind.ExtendsKeyword) { + error(errorLocation, Diagnostics.An_interface_cannot_extend_a_primitive_type_like_0_It_can_only_extend_other_named_object_types, unescapeLeadingUnderscores(name)); + } + else if (containerKind === SyntaxKind.ClassDeclaration && heritageKind === SyntaxKind.ExtendsKeyword) { + error(errorLocation, Diagnostics.A_class_cannot_extend_a_primitive_type_like_0_Classes_can_only_extend_constructable_values, unescapeLeadingUnderscores(name)); + } + else if (containerKind === SyntaxKind.ClassDeclaration && heritageKind === SyntaxKind.ImplementsKeyword) { + error(errorLocation, Diagnostics.A_class_cannot_implement_a_primitive_type_like_0_It_can_only_implement_other_named_object_types, unescapeLeadingUnderscores(name)); + } + } + else { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here, unescapeLeadingUnderscores(name)); + } + return true; + } + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Type & ~SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + const allFlags = symbol && getSymbolFlags(symbol); + if (symbol && allFlags !== undefined && !(allFlags & SymbolFlags.Value)) { + const rawName = unescapeLeadingUnderscores(name); + if (isES2015OrLaterConstructorName(name)) { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_es2015_or_later, rawName); + } + else if (maybeMappedType(errorLocation, symbol)) { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here_Did_you_mean_to_use_1_in_0, rawName, rawName === "K" ? "P" : "K"); + } + else { + error(errorLocation, Diagnostics._0_only_refers_to_a_type_but_is_being_used_as_a_value_here, rawName); + } + return true; + } + } + return false; + } + + function maybeMappedType(node: Node, symbol: Symbol) { + const container = findAncestor(node.parent, n => isComputedPropertyName(n) || isPropertySignature(n) ? false : isTypeLiteralNode(n) || "quit") as TypeLiteralNode | undefined; + if (container && container.members.length === 1) { + const type = getDeclaredTypeOfSymbol(symbol); + return !!(type.flags & TypeFlags.Union) && allTypesAssignableToKind(type, TypeFlags.StringOrNumberLiteral, /*strict*/ true); + } + return false; + } + + function isES2015OrLaterConstructorName(n: __String) { + switch (n) { + case "Promise": + case "Symbol": + case "Map": + case "WeakMap": + case "Set": + case "WeakSet": + return true; + } + return false; + } + + function checkAndReportErrorForUsingNamespaceAsTypeOrValue(errorLocation: Node, name: __String, meaning: SymbolFlags): boolean { + if (meaning & (SymbolFlags.Value & ~SymbolFlags.Type)) { + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.NamespaceModule, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + if (symbol) { + error( + errorLocation, + Diagnostics.Cannot_use_namespace_0_as_a_value, + unescapeLeadingUnderscores(name), + ); + return true; + } + } + else if (meaning & (SymbolFlags.Type & ~SymbolFlags.Value)) { + const symbol = resolveSymbol(resolveName(errorLocation, name, SymbolFlags.Module, /*nameNotFoundMessage*/ undefined, /*isUse*/ false)); + if (symbol) { + error(errorLocation, Diagnostics.Cannot_use_namespace_0_as_a_type, unescapeLeadingUnderscores(name)); + return true; + } + } + return false; + } + + function checkResolvedBlockScopedVariable(result: Symbol, errorLocation: Node): void { + Debug.assert(!!(result.flags & SymbolFlags.BlockScopedVariable || result.flags & SymbolFlags.Class || result.flags & SymbolFlags.Enum)); + if (result.flags & (SymbolFlags.Function | SymbolFlags.FunctionScopedVariable | SymbolFlags.Assignment) && result.flags & SymbolFlags.Class) { + // constructor functions aren't block scoped + return; + } + // Block-scoped variables cannot be used before their definition + const declaration = result.declarations?.find( + d => isBlockOrCatchScoped(d) || isClassLike(d) || (d.kind === SyntaxKind.EnumDeclaration), + ); + + if (declaration === undefined) return Debug.fail("checkResolvedBlockScopedVariable could not find block-scoped declaration"); + + if (!(declaration.flags & NodeFlags.Ambient) && !isBlockScopedNameDeclaredBeforeUse(declaration, errorLocation)) { + let diagnosticMessage; + const declarationName = declarationNameToString(getNameOfDeclaration(declaration)); + if (result.flags & SymbolFlags.BlockScopedVariable) { + diagnosticMessage = error(errorLocation, Diagnostics.Block_scoped_variable_0_used_before_its_declaration, declarationName); + } + else if (result.flags & SymbolFlags.Class) { + diagnosticMessage = error(errorLocation, Diagnostics.Class_0_used_before_its_declaration, declarationName); + } + else if (result.flags & SymbolFlags.RegularEnum) { + diagnosticMessage = error(errorLocation, Diagnostics.Enum_0_used_before_its_declaration, declarationName); + } + else { + Debug.assert(!!(result.flags & SymbolFlags.ConstEnum)); + if (getIsolatedModules(compilerOptions)) { + diagnosticMessage = error(errorLocation, Diagnostics.Enum_0_used_before_its_declaration, declarationName); + } + } + + if (diagnosticMessage) { + addRelatedInfo(diagnosticMessage, createDiagnosticForNode(declaration, Diagnostics._0_is_declared_here, declarationName)); + } + } + } + + /* Starting from 'initial' node walk up the parent chain until 'stopAt' node is reached. + * If at any point current node is equal to 'parent' node - return true. + * If current node is an IIFE, continue walking up. + * Return false if 'stopAt' node is reached or isFunctionLike(current) === true. + */ + function isSameScopeDescendentOf(initial: Node, parent: Node | undefined, stopAt: Node): boolean { + return !!parent && !!findAncestor(initial, n => + n === parent + || (n === stopAt || isFunctionLike(n) && (!getImmediatelyInvokedFunctionExpression(n) || (getFunctionFlags(n) & FunctionFlags.AsyncGenerator)) ? "quit" : false)); + } + + function getAnyImportSyntax(node: Node): AnyImportOrJsDocImport | undefined { + switch (node.kind) { + case SyntaxKind.ImportEqualsDeclaration: + return node as ImportEqualsDeclaration; + case SyntaxKind.ImportClause: + return (node as ImportClause).parent; + case SyntaxKind.NamespaceImport: + return (node as NamespaceImport).parent.parent; + case SyntaxKind.ImportSpecifier: + return (node as ImportSpecifier).parent.parent.parent; + default: + return undefined; + } + } + + function getDeclarationOfAliasSymbol(symbol: Symbol): Declaration | undefined { + return symbol.declarations && findLast(symbol.declarations, isAliasSymbolDeclaration); + } + + /** + * An alias symbol is created by one of the following declarations: + * import = ... + * import from ... + * import * as from ... + * import { x as } from ... + * export { x as } from ... + * export * as ns from ... + * export = + * export default + * module.exports = + * {} + * {name: } + * const { x } = require ... + */ + function isAliasSymbolDeclaration(node: Node): boolean { + return node.kind === SyntaxKind.ImportEqualsDeclaration + || node.kind === SyntaxKind.NamespaceExportDeclaration + || node.kind === SyntaxKind.ImportClause && !!(node as ImportClause).name + || node.kind === SyntaxKind.NamespaceImport + || node.kind === SyntaxKind.NamespaceExport + || node.kind === SyntaxKind.ImportSpecifier + || node.kind === SyntaxKind.ExportSpecifier + || node.kind === SyntaxKind.ExportAssignment && exportAssignmentIsAlias(node as ExportAssignment) + || isBinaryExpression(node) && getAssignmentDeclarationKind(node) === AssignmentDeclarationKind.ModuleExports && exportAssignmentIsAlias(node) + || isAccessExpression(node) + && isBinaryExpression(node.parent) + && node.parent.left === node + && node.parent.operatorToken.kind === SyntaxKind.EqualsToken + && isAliasableOrJsExpression(node.parent.right) + || node.kind === SyntaxKind.ShorthandPropertyAssignment + || node.kind === SyntaxKind.PropertyAssignment && isAliasableOrJsExpression((node as PropertyAssignment).initializer) + || node.kind === SyntaxKind.VariableDeclaration && isVariableDeclarationInitializedToBareOrAccessedRequire(node) + || node.kind === SyntaxKind.BindingElement && isVariableDeclarationInitializedToBareOrAccessedRequire(node.parent.parent); + } + + function isAliasableOrJsExpression(e: Expression) { + return isAliasableExpression(e) || isFunctionExpression(e) && isJSConstructor(e); + } + + function getTargetOfImportEqualsDeclaration(node: ImportEqualsDeclaration | VariableDeclaration, dontResolveAlias: boolean): Symbol | undefined { + const commonJSPropertyAccess = getCommonJSPropertyAccess(node); + if (commonJSPropertyAccess) { + const name = (getLeftmostAccessExpression(commonJSPropertyAccess.expression) as CallExpression).arguments[0] as StringLiteral; + return isIdentifier(commonJSPropertyAccess.name) + ? resolveSymbol(getPropertyOfType(resolveExternalModuleTypeByLiteral(name), commonJSPropertyAccess.name.escapedText)) + : undefined; + } + if (isVariableDeclaration(node) || node.moduleReference.kind === SyntaxKind.ExternalModuleReference) { + const immediate = resolveExternalModuleName( + node, + getExternalModuleRequireArgument(node) || getExternalModuleImportEqualsDeclarationExpression(node), + ); + const resolved = resolveExternalModuleSymbol(immediate); + markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); + return resolved; + } + const resolved = getSymbolOfPartOfRightHandSideOfImportEquals(node.moduleReference, dontResolveAlias); + checkAndReportErrorForResolvingImportAliasToTypeOnlySymbol(node, resolved); + return resolved; + } + + function checkAndReportErrorForResolvingImportAliasToTypeOnlySymbol(node: ImportEqualsDeclaration, resolved: Symbol | undefined) { + if (markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false) && !node.isTypeOnly) { + const typeOnlyDeclaration = getTypeOnlyAliasDeclaration(getSymbolOfDeclaration(node))!; + const isExport = typeOnlyDeclaration.kind === SyntaxKind.ExportSpecifier || typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration; + const message = isExport + ? Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_exported_using_export_type + : Diagnostics.An_import_alias_cannot_reference_a_declaration_that_was_imported_using_import_type; + const relatedMessage = isExport + ? Diagnostics._0_was_exported_here + : Diagnostics._0_was_imported_here; + + // TODO: how to get name for export *? + const name = typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration ? "*" : moduleExportNameTextUnescaped(typeOnlyDeclaration.name); + addRelatedInfo(error(node.moduleReference, message), createDiagnosticForNode(typeOnlyDeclaration, relatedMessage, name)); + } + } + + function resolveExportByName(moduleSymbol: Symbol, name: __String, sourceNode: TypeOnlyCompatibleAliasDeclaration | undefined, dontResolveAlias: boolean) { + const exportValue = moduleSymbol.exports!.get(InternalSymbolName.ExportEquals); + const exportSymbol = exportValue + ? getPropertyOfType(getTypeOfSymbol(exportValue), name, /*skipObjectFunctionPropertyAugment*/ true) + : moduleSymbol.exports!.get(name); + const resolved = resolveSymbol(exportSymbol, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(sourceNode, exportSymbol, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function isSyntacticDefault(node: Node) { + return ((isExportAssignment(node) && !node.isExportEquals) + || hasSyntacticModifier(node, ModifierFlags.Default) + || isExportSpecifier(node) + || isNamespaceExport(node)); + } + + function getUsageModeForExpression(usage: Expression) { + return isStringLiteralLike(usage) ? host.getModeForUsageLocation(getSourceFileOfNode(usage), usage) : undefined; + } + + function isESMFormatImportImportingCommonjsFormatFile(usageMode: ResolutionMode, targetMode: ResolutionMode) { + return usageMode === ModuleKind.ESNext && targetMode === ModuleKind.CommonJS; + } + + function isOnlyImportedAsDefault(usage: Expression) { + const usageMode = getUsageModeForExpression(usage); + return usageMode === ModuleKind.ESNext && endsWith((usage as StringLiteralLike).text, Extension.Json); + } + + function canHaveSyntheticDefault(file: SourceFile | undefined, moduleSymbol: Symbol, dontResolveAlias: boolean, usage: Expression) { + const usageMode = file && getUsageModeForExpression(usage); + if (file && usageMode !== undefined && ModuleKind.Node16 <= moduleKind && moduleKind <= ModuleKind.NodeNext) { + const result = isESMFormatImportImportingCommonjsFormatFile(usageMode, file.impliedNodeFormat); + if (usageMode === ModuleKind.ESNext || result) { + return result; + } + // fallthrough on cjs usages so we imply defaults for interop'd imports, too + } + if (!allowSyntheticDefaultImports) { + return false; + } + // Declaration files (and ambient modules) + if (!file || file.isDeclarationFile) { + // Definitely cannot have a synthetic default if they have a syntactic default member specified + const defaultExportSymbol = resolveExportByName(moduleSymbol, InternalSymbolName.Default, /*sourceNode*/ undefined, /*dontResolveAlias*/ true); // Dont resolve alias because we want the immediately exported symbol's declaration + if (defaultExportSymbol && some(defaultExportSymbol.declarations, isSyntacticDefault)) { + return false; + } + // It _might_ still be incorrect to assume there is no __esModule marker on the import at runtime, even if there is no `default` member + // So we check a bit more, + if (resolveExportByName(moduleSymbol, escapeLeadingUnderscores("__esModule"), /*sourceNode*/ undefined, dontResolveAlias)) { + // If there is an `__esModule` specified in the declaration (meaning someone explicitly added it or wrote it in their code), + // it definitely is a module and does not have a synthetic default + return false; + } + // There are _many_ declaration files not written with esmodules in mind that still get compiled into a format with __esModule set + // Meaning there may be no default at runtime - however to be on the permissive side, we allow access to a synthetic default member + // as there is no marker to indicate if the accompanying JS has `__esModule` or not, or is even native esm + return true; + } + // TypeScript files never have a synthetic default (as they are always emitted with an __esModule marker) _unless_ they contain an export= statement + if (!isSourceFileJS(file)) { + return hasExportAssignmentSymbol(moduleSymbol); + } + // JS files have a synthetic default if they do not contain ES2015+ module syntax (export = is not valid in js) _and_ do not have an __esModule marker + return typeof file.externalModuleIndicator !== "object" && !resolveExportByName(moduleSymbol, escapeLeadingUnderscores("__esModule"), /*sourceNode*/ undefined, dontResolveAlias); + } + + function getTargetOfImportClause(node: ImportClause, dontResolveAlias: boolean): Symbol | undefined { + const moduleSymbol = resolveExternalModuleName(node, node.parent.moduleSpecifier); + if (moduleSymbol) { + return getTargetofModuleDefault(moduleSymbol, node, dontResolveAlias); + } + } + + function getTargetofModuleDefault(moduleSymbol: Symbol, node: ImportClause | ImportOrExportSpecifier, dontResolveAlias: boolean) { + let exportDefaultSymbol: Symbol | undefined; + if (isShorthandAmbientModuleSymbol(moduleSymbol)) { + exportDefaultSymbol = moduleSymbol; + } + else { + exportDefaultSymbol = resolveExportByName(moduleSymbol, InternalSymbolName.Default, node, dontResolveAlias); + } + + const file = moduleSymbol.declarations?.find(isSourceFile); + const specifier = getModuleSpecifierForImportOrExport(node); + if (!specifier) { + return exportDefaultSymbol; + } + const hasDefaultOnly = isOnlyImportedAsDefault(specifier); + const hasSyntheticDefault = canHaveSyntheticDefault(file, moduleSymbol, dontResolveAlias, specifier); + if (!exportDefaultSymbol && !hasSyntheticDefault && !hasDefaultOnly) { + if (hasExportAssignmentSymbol(moduleSymbol) && !allowSyntheticDefaultImports) { + const compilerOptionName = moduleKind >= ModuleKind.ES2015 ? "allowSyntheticDefaultImports" : "esModuleInterop"; + const exportEqualsSymbol = moduleSymbol.exports!.get(InternalSymbolName.ExportEquals); + const exportAssignment = exportEqualsSymbol!.valueDeclaration; + const err = error(node.name, Diagnostics.Module_0_can_only_be_default_imported_using_the_1_flag, symbolToString(moduleSymbol), compilerOptionName); + + if (exportAssignment) { + addRelatedInfo( + err, + createDiagnosticForNode( + exportAssignment, + Diagnostics.This_module_is_declared_with_export_and_can_only_be_used_with_a_default_import_when_using_the_0_flag, + compilerOptionName, + ), + ); + } + } + else if (isImportClause(node)) { + reportNonDefaultExport(moduleSymbol, node); + } + else { + errorNoModuleMemberSymbol(moduleSymbol, moduleSymbol, node, isImportOrExportSpecifier(node) && node.propertyName || node.name); + } + } + else if (hasSyntheticDefault || hasDefaultOnly) { + // per emit behavior, a synthetic default overrides a "real" .default member if `__esModule` is not present + const resolved = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias) || resolveSymbol(moduleSymbol, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, moduleSymbol, resolved, /*overwriteEmpty*/ false); + return resolved; + } + markSymbolOfAliasDeclarationIfTypeOnly(node, exportDefaultSymbol, /*finalTarget*/ undefined, /*overwriteEmpty*/ false); + return exportDefaultSymbol; + } + + function getModuleSpecifierForImportOrExport(node: ImportEqualsDeclaration | ImportClause | NamespaceImport | ImportOrExportSpecifier): Expression | undefined { + switch (node.kind) { + case SyntaxKind.ImportClause: + return node.parent.moduleSpecifier; + case SyntaxKind.ImportEqualsDeclaration: + return isExternalModuleReference(node.moduleReference) ? node.moduleReference.expression : undefined; + case SyntaxKind.NamespaceImport: + return node.parent.parent.moduleSpecifier; + case SyntaxKind.ImportSpecifier: + return node.parent.parent.parent.moduleSpecifier; + case SyntaxKind.ExportSpecifier: + return node.parent.parent.moduleSpecifier; + default: + return Debug.assertNever(node); + } + } + + function reportNonDefaultExport(moduleSymbol: Symbol, node: ImportClause) { + if (moduleSymbol.exports?.has(node.symbol.escapedName)) { + error( + node.name, + Diagnostics.Module_0_has_no_default_export_Did_you_mean_to_use_import_1_from_0_instead, + symbolToString(moduleSymbol), + symbolToString(node.symbol), + ); + } + else { + const diagnostic = error(node.name, Diagnostics.Module_0_has_no_default_export, symbolToString(moduleSymbol)); + const exportStar = moduleSymbol.exports?.get(InternalSymbolName.ExportStar); + if (exportStar) { + const defaultExport = exportStar.declarations?.find(decl => + !!( + isExportDeclaration(decl) && decl.moduleSpecifier && + resolveExternalModuleName(decl, decl.moduleSpecifier)?.exports?.has(InternalSymbolName.Default) + ) + ); + if (defaultExport) { + addRelatedInfo(diagnostic, createDiagnosticForNode(defaultExport, Diagnostics.export_Asterisk_does_not_re_export_a_default)); + } + } + } + } + + function getTargetOfNamespaceImport(node: NamespaceImport, dontResolveAlias: boolean): Symbol | undefined { + const moduleSpecifier = node.parent.parent.moduleSpecifier; + const immediate = resolveExternalModuleName(node, moduleSpecifier); + const resolved = resolveESModuleSymbol(immediate, moduleSpecifier, dontResolveAlias, /*suppressInteropError*/ false); + markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getTargetOfNamespaceExport(node: NamespaceExport, dontResolveAlias: boolean): Symbol | undefined { + const moduleSpecifier = node.parent.moduleSpecifier; + const immediate = moduleSpecifier && resolveExternalModuleName(node, moduleSpecifier); + const resolved = moduleSpecifier && resolveESModuleSymbol(immediate, moduleSpecifier, dontResolveAlias, /*suppressInteropError*/ false); + markSymbolOfAliasDeclarationIfTypeOnly(node, immediate, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + // This function creates a synthetic symbol that combines the value side of one symbol with the + // type/namespace side of another symbol. Consider this example: + // + // declare module graphics { + // interface Point { + // x: number; + // y: number; + // } + // } + // declare var graphics: { + // Point: new (x: number, y: number) => graphics.Point; + // } + // declare module "graphics" { + // export = graphics; + // } + // + // An 'import { Point } from "graphics"' needs to create a symbol that combines the value side 'Point' + // property with the type/namespace side interface 'Point'. + function combineValueAndTypeSymbols(valueSymbol: Symbol, typeSymbol: Symbol): Symbol { + if (valueSymbol === unknownSymbol && typeSymbol === unknownSymbol) { + return unknownSymbol; + } + if (valueSymbol.flags & (SymbolFlags.Type | SymbolFlags.Namespace)) { + return valueSymbol; + } + const result = createSymbol(valueSymbol.flags | typeSymbol.flags, valueSymbol.escapedName); + Debug.assert(valueSymbol.declarations || typeSymbol.declarations); + result.declarations = deduplicate(concatenate(valueSymbol.declarations!, typeSymbol.declarations), equateValues); + result.parent = valueSymbol.parent || typeSymbol.parent; + if (valueSymbol.valueDeclaration) result.valueDeclaration = valueSymbol.valueDeclaration; + if (typeSymbol.members) result.members = new Map(typeSymbol.members); + if (valueSymbol.exports) result.exports = new Map(valueSymbol.exports); + return result; + } + + function getExportOfModule(symbol: Symbol, nameText: __String, specifier: Declaration, dontResolveAlias: boolean): Symbol | undefined { + if (symbol.flags & SymbolFlags.Module) { + const exportSymbol = getExportsOfSymbol(symbol).get(nameText); + const resolved = resolveSymbol(exportSymbol, dontResolveAlias); + const exportStarDeclaration = getSymbolLinks(symbol).typeOnlyExportStarMap?.get(nameText); + markSymbolOfAliasDeclarationIfTypeOnly(specifier, exportSymbol, resolved, /*overwriteEmpty*/ false, exportStarDeclaration, nameText); + return resolved; + } + } + + function getPropertyOfVariable(symbol: Symbol, name: __String): Symbol | undefined { + if (symbol.flags & SymbolFlags.Variable) { + const typeAnnotation = (symbol.valueDeclaration as VariableDeclaration).type; + if (typeAnnotation) { + return resolveSymbol(getPropertyOfType(getTypeFromTypeNode(typeAnnotation), name)); + } + } + } + + function getExternalModuleMember(node: ImportDeclaration | ExportDeclaration | VariableDeclaration | JSDocImportTag, specifier: ImportOrExportSpecifier | BindingElement | PropertyAccessExpression, dontResolveAlias = false): Symbol | undefined { + const moduleSpecifier = getExternalModuleRequireArgument(node) || (node as ImportDeclaration | ExportDeclaration | JSDocImportTag).moduleSpecifier!; + const moduleSymbol = resolveExternalModuleName(node, moduleSpecifier)!; // TODO: GH#18217 + const name = !isPropertyAccessExpression(specifier) && specifier.propertyName || specifier.name; + if (!isIdentifier(name) && name.kind !== SyntaxKind.StringLiteral) { + return undefined; + } + const nameText = moduleExportNameTextEscaped(name); + const suppressInteropError = nameText === InternalSymbolName.Default && allowSyntheticDefaultImports; + const targetSymbol = resolveESModuleSymbol(moduleSymbol, moduleSpecifier, /*dontResolveAlias*/ false, suppressInteropError); + if (targetSymbol) { + // Note: The empty string is a valid module export name: + // + // import { "" as foo } from "./foo"; + // export { foo as "" }; + // + if (nameText || name.kind === SyntaxKind.StringLiteral) { + if (isShorthandAmbientModuleSymbol(moduleSymbol)) { + return moduleSymbol; + } + + let symbolFromVariable: Symbol | undefined; + // First check if module was specified with "export=". If so, get the member from the resolved type + if (moduleSymbol && moduleSymbol.exports && moduleSymbol.exports.get(InternalSymbolName.ExportEquals)) { + symbolFromVariable = getPropertyOfType(getTypeOfSymbol(targetSymbol), nameText, /*skipObjectFunctionPropertyAugment*/ true); + } + else { + symbolFromVariable = getPropertyOfVariable(targetSymbol, nameText); + } + // if symbolFromVariable is export - get its final target + symbolFromVariable = resolveSymbol(symbolFromVariable, dontResolveAlias); + + let symbolFromModule = getExportOfModule(targetSymbol, nameText, specifier, dontResolveAlias); + if (symbolFromModule === undefined && nameText === InternalSymbolName.Default) { + const file = moduleSymbol.declarations?.find(isSourceFile); + if (isOnlyImportedAsDefault(moduleSpecifier) || canHaveSyntheticDefault(file, moduleSymbol, dontResolveAlias, moduleSpecifier)) { + symbolFromModule = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias) || resolveSymbol(moduleSymbol, dontResolveAlias); + } + } + + const symbol = symbolFromModule && symbolFromVariable && symbolFromModule !== symbolFromVariable ? + combineValueAndTypeSymbols(symbolFromVariable, symbolFromModule) : + symbolFromModule || symbolFromVariable; + if (!symbol) { + errorNoModuleMemberSymbol(moduleSymbol, targetSymbol, node, name); + } + return symbol; + } + } + } + + function errorNoModuleMemberSymbol(moduleSymbol: Symbol, targetSymbol: Symbol, node: Node, name: ModuleExportName) { + const moduleName = getFullyQualifiedName(moduleSymbol, node); + const declarationName = declarationNameToString(name); + const suggestion = isIdentifier(name) ? getSuggestedSymbolForNonexistentModule(name, targetSymbol) : undefined; + if (suggestion !== undefined) { + const suggestionName = symbolToString(suggestion); + const diagnostic = error(name, Diagnostics._0_has_no_exported_member_named_1_Did_you_mean_2, moduleName, declarationName, suggestionName); + if (suggestion.valueDeclaration) { + addRelatedInfo(diagnostic, createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestionName)); + } + } + else { + if (moduleSymbol.exports?.has(InternalSymbolName.Default)) { + error( + name, + Diagnostics.Module_0_has_no_exported_member_1_Did_you_mean_to_use_import_1_from_0_instead, + moduleName, + declarationName, + ); + } + else { + reportNonExportedMember(node, name, declarationName, moduleSymbol, moduleName); + } + } + } + + function reportNonExportedMember(node: Node, name: ModuleExportName, declarationName: string, moduleSymbol: Symbol, moduleName: string): void { + const localSymbol = tryCast(moduleSymbol.valueDeclaration, canHaveLocals)?.locals?.get(moduleExportNameTextEscaped(name)); + const exports = moduleSymbol.exports; + if (localSymbol) { + const exportedEqualsSymbol = exports?.get(InternalSymbolName.ExportEquals); + if (exportedEqualsSymbol) { + getSymbolIfSameReference(exportedEqualsSymbol, localSymbol) ? reportInvalidImportEqualsExportMember(node, name, declarationName, moduleName) : + error(name, Diagnostics.Module_0_has_no_exported_member_1, moduleName, declarationName); + } + else { + const exportedSymbol = exports ? find(symbolsToArray(exports), symbol => !!getSymbolIfSameReference(symbol, localSymbol)) : undefined; + const diagnostic = exportedSymbol ? error(name, Diagnostics.Module_0_declares_1_locally_but_it_is_exported_as_2, moduleName, declarationName, symbolToString(exportedSymbol)) : + error(name, Diagnostics.Module_0_declares_1_locally_but_it_is_not_exported, moduleName, declarationName); + if (localSymbol.declarations) { + addRelatedInfo(diagnostic, ...map(localSymbol.declarations, (decl, index) => createDiagnosticForNode(decl, index === 0 ? Diagnostics._0_is_declared_here : Diagnostics.and_here, declarationName))); + } + } + } + else { + error(name, Diagnostics.Module_0_has_no_exported_member_1, moduleName, declarationName); + } + } + + function reportInvalidImportEqualsExportMember(node: Node, name: ModuleExportName, declarationName: string, moduleName: string) { + if (moduleKind >= ModuleKind.ES2015) { + const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_a_default_import : + Diagnostics._0_can_only_be_imported_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; + error(name, message, declarationName); + } + else { + if (isInJSFile(node)) { + const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_a_require_call_or_by_using_a_default_import : + Diagnostics._0_can_only_be_imported_by_using_a_require_call_or_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; + error(name, message, declarationName); + } + else { + const message = getESModuleInterop(compilerOptions) ? Diagnostics._0_can_only_be_imported_by_using_import_1_require_2_or_a_default_import : + Diagnostics._0_can_only_be_imported_by_using_import_1_require_2_or_by_turning_on_the_esModuleInterop_flag_and_using_a_default_import; + error(name, message, declarationName, declarationName, moduleName); + } + } + } + + function getTargetOfImportSpecifier(node: ImportSpecifier | BindingElement, dontResolveAlias: boolean): Symbol | undefined { + if (isImportSpecifier(node) && moduleExportNameIsDefault(node.propertyName || node.name)) { + const specifier = getModuleSpecifierForImportOrExport(node); + const moduleSymbol = specifier && resolveExternalModuleName(node, specifier); + if (moduleSymbol) { + return getTargetofModuleDefault(moduleSymbol, node, dontResolveAlias); + } + } + const root = isBindingElement(node) ? getRootDeclaration(node) as VariableDeclaration : node.parent.parent.parent; + const commonJSPropertyAccess = getCommonJSPropertyAccess(root); + const resolved = getExternalModuleMember(root, commonJSPropertyAccess || node, dontResolveAlias); + const name = node.propertyName || node.name; + if (commonJSPropertyAccess && resolved && isIdentifier(name)) { + return resolveSymbol(getPropertyOfType(getTypeOfSymbol(resolved), name.escapedText), dontResolveAlias); + } + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getCommonJSPropertyAccess(node: Node) { + if (isVariableDeclaration(node) && node.initializer && isPropertyAccessExpression(node.initializer)) { + return node.initializer; + } + } + + function getTargetOfNamespaceExportDeclaration(node: NamespaceExportDeclaration, dontResolveAlias: boolean): Symbol | undefined { + if (canHaveSymbol(node.parent)) { + const resolved = resolveExternalModuleSymbol(node.parent.symbol, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + } + + function getTargetOfExportSpecifier(node: ExportSpecifier, meaning: SymbolFlags, dontResolveAlias?: boolean) { + const name = node.propertyName || node.name; + if (moduleExportNameIsDefault(name)) { + const specifier = getModuleSpecifierForImportOrExport(node); + const moduleSymbol = specifier && resolveExternalModuleName(node, specifier); + if (moduleSymbol) { + return getTargetofModuleDefault(moduleSymbol, node, !!dontResolveAlias); + } + } + const resolved = node.parent.parent.moduleSpecifier ? + getExternalModuleMember(node.parent.parent, node, dontResolveAlias) : + name.kind === SyntaxKind.StringLiteral ? undefined : // Skip for invalid syntax like this: export { "x" } + resolveEntityName(name, meaning, /*ignoreErrors*/ false, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getTargetOfExportAssignment(node: ExportAssignment | BinaryExpression, dontResolveAlias: boolean): Symbol | undefined { + const expression = isExportAssignment(node) ? node.expression : node.right; + const resolved = getTargetOfAliasLikeExpression(expression, dontResolveAlias); + markSymbolOfAliasDeclarationIfTypeOnly(node, /*immediateTarget*/ undefined, resolved, /*overwriteEmpty*/ false); + return resolved; + } + + function getTargetOfAliasLikeExpression(expression: Expression, dontResolveAlias: boolean) { + if (isClassExpression(expression)) { + return checkExpressionCached(expression).symbol; + } + if (!isEntityName(expression) && !isEntityNameExpression(expression)) { + return undefined; + } + const aliasLike = resolveEntityName(expression, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ true, dontResolveAlias); + if (aliasLike) { + return aliasLike; + } + checkExpressionCached(expression); + return getNodeLinks(expression).resolvedSymbol; + } + + function getTargetOfAccessExpression(node: AccessExpression, dontRecursivelyResolve: boolean): Symbol | undefined { + if (!(isBinaryExpression(node.parent) && node.parent.left === node && node.parent.operatorToken.kind === SyntaxKind.EqualsToken)) { + return undefined; + } + + return getTargetOfAliasLikeExpression(node.parent.right, dontRecursivelyResolve); + } + + function getTargetOfAliasDeclaration(node: Declaration, dontRecursivelyResolve = false): Symbol | undefined { + switch (node.kind) { + case SyntaxKind.ImportEqualsDeclaration: + case SyntaxKind.VariableDeclaration: + return getTargetOfImportEqualsDeclaration(node as ImportEqualsDeclaration | VariableDeclaration, dontRecursivelyResolve); + case SyntaxKind.ImportClause: + return getTargetOfImportClause(node as ImportClause, dontRecursivelyResolve); + case SyntaxKind.NamespaceImport: + return getTargetOfNamespaceImport(node as NamespaceImport, dontRecursivelyResolve); + case SyntaxKind.NamespaceExport: + return getTargetOfNamespaceExport(node as NamespaceExport, dontRecursivelyResolve); + case SyntaxKind.ImportSpecifier: + case SyntaxKind.BindingElement: + return getTargetOfImportSpecifier(node as ImportSpecifier | BindingElement, dontRecursivelyResolve); + case SyntaxKind.ExportSpecifier: + return getTargetOfExportSpecifier(node as ExportSpecifier, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, dontRecursivelyResolve); + case SyntaxKind.ExportAssignment: + case SyntaxKind.BinaryExpression: + return getTargetOfExportAssignment(node as ExportAssignment | BinaryExpression, dontRecursivelyResolve); + case SyntaxKind.NamespaceExportDeclaration: + return getTargetOfNamespaceExportDeclaration(node as NamespaceExportDeclaration, dontRecursivelyResolve); + case SyntaxKind.ShorthandPropertyAssignment: + return resolveEntityName((node as ShorthandPropertyAssignment).name, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ true, dontRecursivelyResolve); + case SyntaxKind.PropertyAssignment: + return getTargetOfAliasLikeExpression((node as PropertyAssignment).initializer, dontRecursivelyResolve); + case SyntaxKind.ElementAccessExpression: + case SyntaxKind.PropertyAccessExpression: + return getTargetOfAccessExpression(node as AccessExpression, dontRecursivelyResolve); + default: + return Debug.fail(); + } + } + + /** + * Indicates that a symbol is an alias that does not merge with a local declaration. + * OR Is a JSContainer which may merge an alias with a local declaration + */ + function isNonLocalAlias(symbol: Symbol | undefined, excludes = SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace): symbol is Symbol { + if (!symbol) return false; + return (symbol.flags & (SymbolFlags.Alias | excludes)) === SymbolFlags.Alias || !!(symbol.flags & SymbolFlags.Alias && symbol.flags & SymbolFlags.Assignment); + } + + function resolveSymbol(symbol: Symbol, dontResolveAlias?: boolean): Symbol; + function resolveSymbol(symbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined; + function resolveSymbol(symbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined { + return !dontResolveAlias && isNonLocalAlias(symbol) ? resolveAlias(symbol) : symbol; + } + + function resolveAlias(symbol: Symbol): Symbol { + Debug.assert((symbol.flags & SymbolFlags.Alias) !== 0, "Should only get Alias here."); + const links = getSymbolLinks(symbol); + if (!links.aliasTarget) { + links.aliasTarget = resolvingSymbol; + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + const target = getTargetOfAliasDeclaration(node); + if (links.aliasTarget === resolvingSymbol) { + links.aliasTarget = target || unknownSymbol; + } + else { + error(node, Diagnostics.Circular_definition_of_import_alias_0, symbolToString(symbol)); + } + } + else if (links.aliasTarget === resolvingSymbol) { + links.aliasTarget = unknownSymbol; + } + return links.aliasTarget; + } + + function tryResolveAlias(symbol: Symbol): Symbol | undefined { + const links = getSymbolLinks(symbol); + if (links.aliasTarget !== resolvingSymbol) { + return resolveAlias(symbol); + } + + return undefined; + } + + /** + * Gets combined flags of a `symbol` and all alias targets it resolves to. `resolveAlias` + * is typically recursive over chains of aliases, but stops mid-chain if an alias is merged + * with another exported symbol, e.g. + * ```ts + * // a.ts + * export const a = 0; + * // b.ts + * export { a } from "./a"; + * export type a = number; + * // c.ts + * import { a } from "./b"; + * ``` + * Calling `resolveAlias` on the `a` in c.ts would stop at the merged symbol exported + * from b.ts, even though there is still more alias to resolve. Consequently, if we were + * trying to determine if the `a` in c.ts has a value meaning, looking at the flags on + * the local symbol and on the symbol returned by `resolveAlias` is not enough. + * @returns SymbolFlags.All if `symbol` is an alias that ultimately resolves to `unknown`; + * combined flags of all alias targets otherwise. + */ + function getSymbolFlags(symbol: Symbol, excludeTypeOnlyMeanings?: boolean, excludeLocalMeanings?: boolean): SymbolFlags { + const typeOnlyDeclaration = excludeTypeOnlyMeanings && getTypeOnlyAliasDeclaration(symbol); + const typeOnlyDeclarationIsExportStar = typeOnlyDeclaration && isExportDeclaration(typeOnlyDeclaration); + const typeOnlyResolution = typeOnlyDeclaration && ( + typeOnlyDeclarationIsExportStar + ? resolveExternalModuleName(typeOnlyDeclaration.moduleSpecifier, typeOnlyDeclaration.moduleSpecifier, /*ignoreErrors*/ true) + : resolveAlias(typeOnlyDeclaration.symbol) + ); + const typeOnlyExportStarTargets = typeOnlyDeclarationIsExportStar && typeOnlyResolution ? getExportsOfModule(typeOnlyResolution) : undefined; + let flags = excludeLocalMeanings ? SymbolFlags.None : symbol.flags; + let seenSymbols; + while (symbol.flags & SymbolFlags.Alias) { + const target = getExportSymbolOfValueSymbolIfExported(resolveAlias(symbol)); + if ( + !typeOnlyDeclarationIsExportStar && target === typeOnlyResolution || + typeOnlyExportStarTargets?.get(target.escapedName) === target + ) { + break; + } + if (target === unknownSymbol) { + return SymbolFlags.All; + } + + // Optimizations - try to avoid creating or adding to + // `seenSymbols` if possible + if (target === symbol || seenSymbols?.has(target)) { + break; + } + if (target.flags & SymbolFlags.Alias) { + if (seenSymbols) { + seenSymbols.add(target); + } + else { + seenSymbols = new Set([symbol, target]); + } + } + flags |= target.flags; + symbol = target; + } + return flags; + } + + /** + * Marks a symbol as type-only if its declaration is syntactically type-only. + * If it is not itself marked type-only, but resolves to a type-only alias + * somewhere in its resolution chain, save a reference to the type-only alias declaration + * so the alias _not_ marked type-only can be identified as _transitively_ type-only. + * + * This function is called on each alias declaration that could be type-only or resolve to + * another type-only alias during `resolveAlias`, so that later, when an alias is used in a + * JS-emitting expression, we can quickly determine if that symbol is effectively type-only + * and issue an error if so. + * + * @param aliasDeclaration The alias declaration not marked as type-only + * @param immediateTarget The symbol to which the alias declaration immediately resolves + * @param finalTarget The symbol to which the alias declaration ultimately resolves + * @param overwriteEmpty Checks `resolvesToSymbol` for type-only declarations even if `aliasDeclaration` + * has already been marked as not resolving to a type-only alias. Used when recursively resolving qualified + * names of import aliases, e.g. `import C = a.b.C`. If namespace `a` is not found to be type-only, the + * import declaration will initially be marked as not resolving to a type-only symbol. But, namespace `b` + * must still be checked for a type-only marker, overwriting the previous negative result if found. + */ + function markSymbolOfAliasDeclarationIfTypeOnly( + aliasDeclaration: Declaration | undefined, + immediateTarget: Symbol | undefined, + finalTarget: Symbol | undefined, + overwriteEmpty: boolean, + exportStarDeclaration?: ExportDeclaration & { readonly isTypeOnly: true; readonly moduleSpecifier: Expression; }, + exportStarName?: __String, + ): boolean { + if (!aliasDeclaration || isPropertyAccessExpression(aliasDeclaration)) return false; + + // If the declaration itself is type-only, mark it and return. + // No need to check what it resolves to. + const sourceSymbol = getSymbolOfDeclaration(aliasDeclaration); + if (isTypeOnlyImportOrExportDeclaration(aliasDeclaration)) { + const links = getSymbolLinks(sourceSymbol); + links.typeOnlyDeclaration = aliasDeclaration; + return true; + } + if (exportStarDeclaration) { + const links = getSymbolLinks(sourceSymbol); + links.typeOnlyDeclaration = exportStarDeclaration; + if (sourceSymbol.escapedName !== exportStarName) { + links.typeOnlyExportStarName = exportStarName; + } + return true; + } + + const links = getSymbolLinks(sourceSymbol); + return markSymbolOfAliasDeclarationIfTypeOnlyWorker(links, immediateTarget, overwriteEmpty) + || markSymbolOfAliasDeclarationIfTypeOnlyWorker(links, finalTarget, overwriteEmpty); + } + + function markSymbolOfAliasDeclarationIfTypeOnlyWorker(aliasDeclarationLinks: SymbolLinks, target: Symbol | undefined, overwriteEmpty: boolean): boolean { + if (target && (aliasDeclarationLinks.typeOnlyDeclaration === undefined || overwriteEmpty && aliasDeclarationLinks.typeOnlyDeclaration === false)) { + const exportSymbol = target.exports?.get(InternalSymbolName.ExportEquals) ?? target; + const typeOnly = exportSymbol.declarations && find(exportSymbol.declarations, isTypeOnlyImportOrExportDeclaration); + aliasDeclarationLinks.typeOnlyDeclaration = typeOnly ?? getSymbolLinks(exportSymbol).typeOnlyDeclaration ?? false; + } + return !!aliasDeclarationLinks.typeOnlyDeclaration; + } + + /** Indicates that a symbol directly or indirectly resolves to a type-only import or export. */ + function getTypeOnlyAliasDeclaration(symbol: Symbol, include?: SymbolFlags): TypeOnlyAliasDeclaration | undefined { + if (!(symbol.flags & SymbolFlags.Alias)) { + return undefined; + } + const links = getSymbolLinks(symbol); + if (links.typeOnlyDeclaration === undefined) { + // We need to set a WIP value here to prevent reentrancy during `getImmediateAliasedSymbol` which, paradoxically, can depend on this + links.typeOnlyDeclaration = false; + const resolved = resolveSymbol(symbol); // do this before the `resolveImmediate` below, as it uses a different circularity cache and we might hide a circularity error if we blindly get the immediate alias first + // While usually the alias will have been marked during the pass by the full typecheck, we may still need to calculate the alias declaration now + markSymbolOfAliasDeclarationIfTypeOnly(symbol.declarations?.[0], getDeclarationOfAliasSymbol(symbol) && getImmediateAliasedSymbol(symbol), resolved, /*overwriteEmpty*/ true); + } + if (include === undefined) { + return links.typeOnlyDeclaration || undefined; + } + if (links.typeOnlyDeclaration) { + const resolved = links.typeOnlyDeclaration.kind === SyntaxKind.ExportDeclaration + ? resolveSymbol(getExportsOfModule(links.typeOnlyDeclaration.symbol.parent!).get(links.typeOnlyExportStarName || symbol.escapedName))! + : resolveAlias(links.typeOnlyDeclaration.symbol); + return getSymbolFlags(resolved) & include ? links.typeOnlyDeclaration : undefined; + } + return undefined; + } + + // This function is only for imports with entity names + function getSymbolOfPartOfRightHandSideOfImportEquals(entityName: EntityName, dontResolveAlias?: boolean): Symbol | undefined { + // There are three things we might try to look for. In the following examples, + // the search term is enclosed in |...|: + // + // import a = |b|; // Namespace + // import a = |b.c|; // Value, type, namespace + // import a = |b.c|.d; // Namespace + if (entityName.kind === SyntaxKind.Identifier && isRightSideOfQualifiedNameOrPropertyAccess(entityName)) { + entityName = entityName.parent as QualifiedName; + } + // Check for case 1 and 3 in the above example + if (entityName.kind === SyntaxKind.Identifier || entityName.parent.kind === SyntaxKind.QualifiedName) { + return resolveEntityName(entityName, SymbolFlags.Namespace, /*ignoreErrors*/ false, dontResolveAlias); + } + else { + // Case 2 in above example + // entityName.kind could be a QualifiedName or a Missing identifier + Debug.assert(entityName.parent.kind === SyntaxKind.ImportEqualsDeclaration); + return resolveEntityName(entityName, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*ignoreErrors*/ false, dontResolveAlias); + } + } + + function getFullyQualifiedName(symbol: Symbol, containingLocation?: Node): string { + return symbol.parent ? getFullyQualifiedName(symbol.parent, containingLocation) + "." + symbolToString(symbol) : symbolToString(symbol, containingLocation, /*meaning*/ undefined, SymbolFormatFlags.DoNotIncludeSymbolChain | SymbolFormatFlags.AllowAnyNodeKind); + } + + function getContainingQualifiedNameNode(node: QualifiedName) { + while (isQualifiedName(node.parent)) { + node = node.parent; + } + return node; + } + + function tryGetQualifiedNameAsValue(node: QualifiedName) { + let left: Identifier | QualifiedName = getFirstIdentifier(node); + let symbol = resolveName(left, left, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (!symbol) { + return undefined; + } + while (isQualifiedName(left.parent)) { + const type = getTypeOfSymbol(symbol); + symbol = getPropertyOfType(type, left.parent.right.escapedText); + if (!symbol) { + return undefined; + } + left = left.parent; + } + return symbol; + } + + /** + * Resolves a qualified name and any involved aliases. + */ + function resolveEntityName(name: EntityNameOrEntityNameExpression, meaning: SymbolFlags, ignoreErrors?: boolean, dontResolveAlias?: boolean, location?: Node): Symbol | undefined { + if (nodeIsMissing(name)) { + return undefined; + } + + const namespaceMeaning = SymbolFlags.Namespace | (isInJSFile(name) ? meaning & SymbolFlags.Value : 0); + let symbol: Symbol | undefined; + if (name.kind === SyntaxKind.Identifier) { + const message = meaning === namespaceMeaning || nodeIsSynthesized(name) ? Diagnostics.Cannot_find_namespace_0 : getCannotFindNameDiagnosticForName(getFirstIdentifier(name)); + const symbolFromJSPrototype = isInJSFile(name) && !nodeIsSynthesized(name) ? resolveEntityNameFromAssignmentDeclaration(name, meaning) : undefined; + symbol = getMergedSymbol(resolveName(location || name, name, meaning, ignoreErrors || symbolFromJSPrototype ? undefined : message, /*isUse*/ true, /*excludeGlobals*/ false)); + if (!symbol) { + return getMergedSymbol(symbolFromJSPrototype); + } + } + else if (name.kind === SyntaxKind.QualifiedName || name.kind === SyntaxKind.PropertyAccessExpression) { + const left = name.kind === SyntaxKind.QualifiedName ? name.left : name.expression; + const right = name.kind === SyntaxKind.QualifiedName ? name.right : name.name; + let namespace = resolveEntityName(left, namespaceMeaning, ignoreErrors, /*dontResolveAlias*/ false, location); + if (!namespace || nodeIsMissing(right)) { + return undefined; + } + else if (namespace === unknownSymbol) { + return namespace; + } + if ( + namespace.valueDeclaration && + isInJSFile(namespace.valueDeclaration) && + getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Bundler && + isVariableDeclaration(namespace.valueDeclaration) && + namespace.valueDeclaration.initializer && + isCommonJsRequire(namespace.valueDeclaration.initializer) + ) { + const moduleName = (namespace.valueDeclaration.initializer as CallExpression).arguments[0] as StringLiteral; + const moduleSym = resolveExternalModuleName(moduleName, moduleName); + if (moduleSym) { + const resolvedModuleSymbol = resolveExternalModuleSymbol(moduleSym); + if (resolvedModuleSymbol) { + namespace = resolvedModuleSymbol; + } + } + } + symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(namespace), right.escapedText, meaning)); + if (!symbol && (namespace.flags & SymbolFlags.Alias)) { + // `namespace` can be resolved further if there was a symbol merge with a re-export + symbol = getMergedSymbol(getSymbol(getExportsOfSymbol(resolveAlias(namespace)), right.escapedText, meaning)); + } + if (!symbol) { + if (!ignoreErrors) { + const namespaceName = getFullyQualifiedName(namespace); + const declarationName = declarationNameToString(right); + const suggestionForNonexistentModule = getSuggestedSymbolForNonexistentModule(right, namespace); + if (suggestionForNonexistentModule) { + error(right, Diagnostics._0_has_no_exported_member_named_1_Did_you_mean_2, namespaceName, declarationName, symbolToString(suggestionForNonexistentModule)); + return undefined; + } + + const containingQualifiedName = isQualifiedName(name) && getContainingQualifiedNameNode(name); + const canSuggestTypeof = globalObjectType // <-- can't pull on types if global types aren't initialized yet + && (meaning & SymbolFlags.Type) + && containingQualifiedName + && !isTypeOfExpression(containingQualifiedName.parent) + && tryGetQualifiedNameAsValue(containingQualifiedName); + if (canSuggestTypeof) { + error( + containingQualifiedName, + Diagnostics._0_refers_to_a_value_but_is_being_used_as_a_type_here_Did_you_mean_typeof_0, + entityNameToString(containingQualifiedName), + ); + return undefined; + } + + if (meaning & SymbolFlags.Namespace && isQualifiedName(name.parent)) { + const exportedTypeSymbol = getMergedSymbol(getSymbol(getExportsOfSymbol(namespace), right.escapedText, SymbolFlags.Type)); + if (exportedTypeSymbol) { + error( + name.parent.right, + Diagnostics.Cannot_access_0_1_because_0_is_a_type_but_not_a_namespace_Did_you_mean_to_retrieve_the_type_of_the_property_1_in_0_with_0_1, + symbolToString(exportedTypeSymbol), + unescapeLeadingUnderscores(name.parent.right.escapedText), + ); + return undefined; + } + } + + error(right, Diagnostics.Namespace_0_has_no_exported_member_1, namespaceName, declarationName); + } + return undefined; + } + } + else { + Debug.assertNever(name, "Unknown entity name kind."); + } + if (!nodeIsSynthesized(name) && isEntityName(name) && (symbol.flags & SymbolFlags.Alias || name.parent.kind === SyntaxKind.ExportAssignment)) { + markSymbolOfAliasDeclarationIfTypeOnly(getAliasDeclarationFromName(name), symbol, /*finalTarget*/ undefined, /*overwriteEmpty*/ true); + } + return (symbol.flags & meaning) || dontResolveAlias ? symbol : resolveAlias(symbol); + } + + /** + * 1. For prototype-property methods like `A.prototype.m = function () ...`, try to resolve names in the scope of `A` too. + * Note that prototype-property assignment to locations outside the current file (eg globals) doesn't work, so + * name resolution won't work either. + * 2. For property assignments like `{ x: function f () { } }`, try to resolve names in the scope of `f` too. + */ + function resolveEntityNameFromAssignmentDeclaration(name: Identifier, meaning: SymbolFlags) { + if (isJSDocTypeReference(name.parent)) { + const secondaryLocation = getAssignmentDeclarationLocation(name.parent); + if (secondaryLocation) { + return resolveName(secondaryLocation, name, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + } + } + } + + function getAssignmentDeclarationLocation(node: TypeReferenceNode): Node | undefined { + const typeAlias = findAncestor(node, node => !(isJSDocNode(node) || node.flags & NodeFlags.JSDoc) ? "quit" : isJSDocTypeAlias(node)); + if (typeAlias) { + return; + } + const host = getJSDocHost(node); + if (host && isExpressionStatement(host) && isPrototypePropertyAssignment(host.expression)) { + // /** @param {K} p */ X.prototype.m = function () { } <-- look for K on X's declaration + const symbol = getSymbolOfDeclaration(host.expression.left); + if (symbol) { + return getDeclarationOfJSPrototypeContainer(symbol); + } + } + if (host && isFunctionExpression(host) && isPrototypePropertyAssignment(host.parent) && isExpressionStatement(host.parent.parent)) { + // X.prototype.m = /** @param {K} p */ function () { } <-- look for K on X's declaration + const symbol = getSymbolOfDeclaration(host.parent.left); + if (symbol) { + return getDeclarationOfJSPrototypeContainer(symbol); + } + } + if ( + host && (isObjectLiteralMethod(host) || isPropertyAssignment(host)) && + isBinaryExpression(host.parent.parent) && + getAssignmentDeclarationKind(host.parent.parent) === AssignmentDeclarationKind.Prototype + ) { + // X.prototype = { /** @param {K} p */m() { } } <-- look for K on X's declaration + const symbol = getSymbolOfDeclaration(host.parent.parent.left as BindableStaticNameExpression); + if (symbol) { + return getDeclarationOfJSPrototypeContainer(symbol); + } + } + const sig = getEffectiveJSDocHost(node); + if (sig && isFunctionLike(sig)) { + const symbol = getSymbolOfDeclaration(sig); + return symbol && symbol.valueDeclaration; + } + } + + function getDeclarationOfJSPrototypeContainer(symbol: Symbol) { + const decl = symbol.parent!.valueDeclaration; + if (!decl) { + return undefined; + } + const initializer = isAssignmentDeclaration(decl) ? getAssignedExpandoInitializer(decl) : + hasOnlyExpressionInitializer(decl) ? getDeclaredExpandoInitializer(decl) : + undefined; + return initializer || decl; + } + + /** + * Get the real symbol of a declaration with an expando initializer. + * + * Normally, declarations have an associated symbol, but when a declaration has an expando + * initializer, the expando's symbol is the one that has all the members merged into it. + */ + function getExpandoSymbol(symbol: Symbol): Symbol | undefined { + const decl = symbol.valueDeclaration; + if (!decl || !isInJSFile(decl) || symbol.flags & SymbolFlags.TypeAlias || getExpandoInitializer(decl, /*isPrototypeAssignment*/ false)) { + return undefined; + } + const init = isVariableDeclaration(decl) ? getDeclaredExpandoInitializer(decl) : getAssignedExpandoInitializer(decl); + if (init) { + const initSymbol = getSymbolOfNode(init); + if (initSymbol) { + return mergeJSSymbols(initSymbol, symbol); + } + } + } + + function resolveExternalModuleName(location: Node, moduleReferenceExpression: Expression, ignoreErrors?: boolean): Symbol | undefined { + const isClassic = getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic; + const errorMessage = isClassic ? + Diagnostics.Cannot_find_module_0_Did_you_mean_to_set_the_moduleResolution_option_to_nodenext_or_to_add_aliases_to_the_paths_option + : Diagnostics.Cannot_find_module_0_or_its_corresponding_type_declarations; + return resolveExternalModuleNameWorker(location, moduleReferenceExpression, ignoreErrors ? undefined : errorMessage); + } + + function resolveExternalModuleNameWorker(location: Node, moduleReferenceExpression: Expression, moduleNotFoundError: DiagnosticMessage | undefined, isForAugmentation = false): Symbol | undefined { + return isStringLiteralLike(moduleReferenceExpression) + ? resolveExternalModule(location, moduleReferenceExpression.text, moduleNotFoundError, moduleReferenceExpression, isForAugmentation) + : undefined; + } + + function resolveExternalModule(location: Node, moduleReference: string, moduleNotFoundError: DiagnosticMessage | undefined, errorNode: Node, isForAugmentation = false): Symbol | undefined { + if (startsWith(moduleReference, "@types/")) { + const diag = Diagnostics.Cannot_import_type_declaration_files_Consider_importing_0_instead_of_1; + const withoutAtTypePrefix = removePrefix(moduleReference, "@types/"); + error(errorNode, diag, withoutAtTypePrefix, moduleReference); + } + + const ambientModule = tryFindAmbientModule(moduleReference, /*withAugmentations*/ true); + if (ambientModule) { + return ambientModule; + } + const currentSourceFile = getSourceFileOfNode(location); + const contextSpecifier = isStringLiteralLike(location) + ? location + : (isModuleDeclaration(location) ? location : location.parent && isModuleDeclaration(location.parent) && location.parent.name === location ? location.parent : undefined)?.name || + (isLiteralImportTypeNode(location) ? location : undefined)?.argument.literal || + (isInJSFile(location) && isJSDocImportTag(location) ? location.moduleSpecifier : undefined) || + (isVariableDeclaration(location) && location.initializer && isRequireCall(location.initializer, /*requireStringLiteralLikeArgument*/ true) ? location.initializer.arguments[0] : undefined) || + findAncestor(location, isImportCall)?.arguments[0] || + findAncestor(location, isImportDeclaration)?.moduleSpecifier || + findAncestor(location, isExternalModuleImportEqualsDeclaration)?.moduleReference.expression || + findAncestor(location, isExportDeclaration)?.moduleSpecifier; + const mode = contextSpecifier && isStringLiteralLike(contextSpecifier) ? host.getModeForUsageLocation(currentSourceFile, contextSpecifier) : currentSourceFile.impliedNodeFormat; + const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions); + const resolvedModule = host.getResolvedModule(currentSourceFile, moduleReference, mode)?.resolvedModule; + const resolutionDiagnostic = resolvedModule && getResolutionDiagnostic(compilerOptions, resolvedModule, currentSourceFile); + const sourceFile = resolvedModule + && (!resolutionDiagnostic || resolutionDiagnostic === Diagnostics.Module_0_was_resolved_to_1_but_jsx_is_not_set) + && host.getSourceFile(resolvedModule.resolvedFileName); + if (sourceFile) { + // If there's a resolutionDiagnostic we need to report it even if a sourceFile is found. + if (resolutionDiagnostic) { + error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName); + } + + if (resolvedModule.resolvedUsingTsExtension && isDeclarationFileName(moduleReference)) { + const importOrExport = findAncestor(location, isImportDeclaration)?.importClause || + findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)); + if (importOrExport && !importOrExport.isTypeOnly || findAncestor(location, isImportCall)) { + error( + errorNode, + Diagnostics.A_declaration_file_cannot_be_imported_without_import_type_Did_you_mean_to_import_an_implementation_file_0_instead, + getSuggestedImportSource(Debug.checkDefined(tryExtractTSExtension(moduleReference))), + ); + } + } + else if (resolvedModule.resolvedUsingTsExtension && !shouldAllowImportingTsExtension(compilerOptions, currentSourceFile.fileName)) { + const importOrExport = findAncestor(location, isImportDeclaration)?.importClause || + findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)); + if (!(importOrExport?.isTypeOnly || findAncestor(location, isImportTypeNode))) { + const tsExtension = Debug.checkDefined(tryExtractTSExtension(moduleReference)); + error(errorNode, Diagnostics.An_import_path_can_only_end_with_a_0_extension_when_allowImportingTsExtensions_is_enabled, tsExtension); + } + } + + if (sourceFile.symbol) { + if (resolvedModule.isExternalLibraryImport && !resolutionExtensionIsTSOrJson(resolvedModule.extension)) { + errorOnImplicitAnyModule(/*isError*/ false, errorNode, currentSourceFile, mode, resolvedModule, moduleReference); + } + if (moduleResolutionKind === ModuleResolutionKind.Node16 || moduleResolutionKind === ModuleResolutionKind.NodeNext) { + const isSyncImport = (currentSourceFile.impliedNodeFormat === ModuleKind.CommonJS && !findAncestor(location, isImportCall)) || !!findAncestor(location, isImportEqualsDeclaration); + const overrideHost = findAncestor(location, l => isImportTypeNode(l) || isExportDeclaration(l) || isImportDeclaration(l)) as ImportTypeNode | ImportDeclaration | ExportDeclaration | undefined; + // An override clause will take effect for type-only imports and import types, and allows importing the types across formats, regardless of + // normal mode restrictions + if (isSyncImport && sourceFile.impliedNodeFormat === ModuleKind.ESNext && !hasResolutionModeOverride(overrideHost)) { + if (findAncestor(location, isImportEqualsDeclaration)) { + // ImportEquals in a ESM file resolving to another ESM file + error(errorNode, Diagnostics.Module_0_cannot_be_imported_using_this_construct_The_specifier_only_resolves_to_an_ES_module_which_cannot_be_imported_with_require_Use_an_ECMAScript_import_instead, moduleReference); + } + else { + // CJS file resolving to an ESM file + let diagnosticDetails; + const ext = tryGetExtensionFromPath(currentSourceFile.fileName); + if (ext === Extension.Ts || ext === Extension.Js || ext === Extension.Tsx || ext === Extension.Jsx) { + const scope = currentSourceFile.packageJsonScope; + const targetExt = ext === Extension.Ts ? Extension.Mts : ext === Extension.Js ? Extension.Mjs : undefined; + if (scope && !scope.contents.packageJsonContent.type) { + if (targetExt) { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_add_the_field_type_Colon_module_to_1, + targetExt, + combinePaths(scope.packageDirectory, "package.json"), + ); + } + else { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_add_the_field_type_Colon_module_to_0, + combinePaths(scope.packageDirectory, "package.json"), + ); + } + } + else { + if (targetExt) { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_change_its_file_extension_to_0_or_create_a_local_package_json_file_with_type_Colon_module, + targetExt, + ); + } + else { + diagnosticDetails = chainDiagnosticMessages( + /*details*/ undefined, + Diagnostics.To_convert_this_file_to_an_ECMAScript_module_create_a_local_package_json_file_with_type_Colon_module, + ); + } + } + } + diagnostics.add(createDiagnosticForNodeFromMessageChain( + getSourceFileOfNode(errorNode), + errorNode, + chainDiagnosticMessages( + diagnosticDetails, + Diagnostics.The_current_file_is_a_CommonJS_module_whose_imports_will_produce_require_calls_however_the_referenced_file_is_an_ECMAScript_module_and_cannot_be_imported_with_require_Consider_writing_a_dynamic_import_0_call_instead, + moduleReference, + ), + )); + } + } + } + // merged symbol is module declaration symbol combined with all augmentations + return getMergedSymbol(sourceFile.symbol); + } + if (moduleNotFoundError) { + // report errors only if it was requested + error(errorNode, Diagnostics.File_0_is_not_a_module, sourceFile.fileName); + } + return undefined; + } + + if (patternAmbientModules) { + const pattern = findBestPatternMatch(patternAmbientModules, _ => _.pattern, moduleReference); + if (pattern) { + // If the module reference matched a pattern ambient module ('*.foo') but there's also a + // module augmentation by the specific name requested ('a.foo'), we store the merged symbol + // by the augmentation name ('a.foo'), because asking for *.foo should not give you exports + // from a.foo. + const augmentation = patternAmbientModuleAugmentations && patternAmbientModuleAugmentations.get(moduleReference); + if (augmentation) { + return getMergedSymbol(augmentation); + } + return getMergedSymbol(pattern.symbol); + } + } + + // May be an untyped module. If so, ignore resolutionDiagnostic. + if (resolvedModule && !resolutionExtensionIsTSOrJson(resolvedModule.extension) && resolutionDiagnostic === undefined || resolutionDiagnostic === Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type) { + if (isForAugmentation) { + const diag = Diagnostics.Invalid_module_name_in_augmentation_Module_0_resolves_to_an_untyped_module_at_1_which_cannot_be_augmented; + error(errorNode, diag, moduleReference, resolvedModule!.resolvedFileName); + } + else { + errorOnImplicitAnyModule(/*isError*/ noImplicitAny && !!moduleNotFoundError, errorNode, currentSourceFile, mode, resolvedModule!, moduleReference); + } + // Failed imports and untyped modules are both treated in an untyped manner; only difference is whether we give a diagnostic first. + return undefined; + } + + if (moduleNotFoundError) { + // See if this was possibly a projectReference redirect + if (resolvedModule) { + const redirect = host.getProjectReferenceRedirect(resolvedModule.resolvedFileName); + if (redirect) { + error(errorNode, Diagnostics.Output_file_0_has_not_been_built_from_source_file_1, redirect, resolvedModule.resolvedFileName); + return undefined; + } + } + + if (resolutionDiagnostic) { + error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName); + } + else { + const isExtensionlessRelativePathImport = pathIsRelative(moduleReference) && !hasExtension(moduleReference); + const resolutionIsNode16OrNext = moduleResolutionKind === ModuleResolutionKind.Node16 || + moduleResolutionKind === ModuleResolutionKind.NodeNext; + if ( + !getResolveJsonModule(compilerOptions) && + fileExtensionIs(moduleReference, Extension.Json) && + moduleResolutionKind !== ModuleResolutionKind.Classic && + hasJsonModuleEmitEnabled(compilerOptions) + ) { + error(errorNode, Diagnostics.Cannot_find_module_0_Consider_using_resolveJsonModule_to_import_module_with_json_extension, moduleReference); + } + else if (mode === ModuleKind.ESNext && resolutionIsNode16OrNext && isExtensionlessRelativePathImport) { + const absoluteRef = getNormalizedAbsolutePath(moduleReference, getDirectoryPath(currentSourceFile.path)); + const suggestedExt = suggestedExtensions.find(([actualExt, _importExt]) => host.fileExists(absoluteRef + actualExt))?.[1]; + if (suggestedExt) { + error(errorNode, Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_ECMAScript_imports_when_moduleResolution_is_node16_or_nodenext_Did_you_mean_0, moduleReference + suggestedExt); + } + else { + error(errorNode, Diagnostics.Relative_import_paths_need_explicit_file_extensions_in_ECMAScript_imports_when_moduleResolution_is_node16_or_nodenext_Consider_adding_an_extension_to_the_import_path); + } + } + else { + if (host.getResolvedModule(currentSourceFile, moduleReference, mode)?.alternateResult) { + const errorInfo = createModuleNotFoundChain(currentSourceFile, host, moduleReference, mode, moduleReference); + errorOrSuggestion(/*isError*/ true, errorNode, chainDiagnosticMessages(errorInfo, moduleNotFoundError, moduleReference)); + } + else { + error(errorNode, moduleNotFoundError, moduleReference); + } + } + } + } + return undefined; + + function getSuggestedImportSource(tsExtension: string) { + const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension); + /** + * Direct users to import source with .js extension if outputting an ES module. + * @see https://github.com/microsoft/TypeScript/issues/42151 + */ + if (emitModuleKindIsNonNodeESM(moduleKind) || mode === ModuleKind.ESNext) { + const preferTs = isDeclarationFileName(moduleReference) && shouldAllowImportingTsExtension(compilerOptions); + const ext = tsExtension === Extension.Mts || tsExtension === Extension.Dmts ? preferTs ? ".mts" : ".mjs" : + tsExtension === Extension.Cts || tsExtension === Extension.Dmts ? preferTs ? ".cts" : ".cjs" : + preferTs ? ".ts" : ".js"; + return importSourceWithoutExtension + ext; + } + return importSourceWithoutExtension; + } + } + + function errorOnImplicitAnyModule(isError: boolean, errorNode: Node, sourceFile: SourceFile, mode: ResolutionMode, { packageId, resolvedFileName }: ResolvedModuleFull, moduleReference: string): void { + let errorInfo: DiagnosticMessageChain | undefined; + if (!isExternalModuleNameRelative(moduleReference) && packageId) { + errorInfo = createModuleNotFoundChain(sourceFile, host, moduleReference, mode, packageId.name); + } + errorOrSuggestion( + isError, + errorNode, + chainDiagnosticMessages( + errorInfo, + Diagnostics.Could_not_find_a_declaration_file_for_module_0_1_implicitly_has_an_any_type, + moduleReference, + resolvedFileName, + ), + ); + } + + function resolveExternalModuleSymbol(moduleSymbol: Symbol, dontResolveAlias?: boolean): Symbol; + function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined; + function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined { + if (moduleSymbol?.exports) { + const exportEquals = resolveSymbol(moduleSymbol.exports.get(InternalSymbolName.ExportEquals), dontResolveAlias); + const exported = getCommonJsExportEquals(getMergedSymbol(exportEquals), getMergedSymbol(moduleSymbol)); + return getMergedSymbol(exported) || moduleSymbol; + } + return undefined; + } + + function getCommonJsExportEquals(exported: Symbol | undefined, moduleSymbol: Symbol): Symbol | undefined { + if (!exported || exported === unknownSymbol || exported === moduleSymbol || moduleSymbol.exports!.size === 1 || exported.flags & SymbolFlags.Alias) { + return exported; + } + const links = getSymbolLinks(exported); + if (links.cjsExportMerged) { + return links.cjsExportMerged; + } + const merged = exported.flags & SymbolFlags.Transient ? exported : cloneSymbol(exported); + merged.flags = merged.flags | SymbolFlags.ValueModule; + if (merged.exports === undefined) { + merged.exports = createSymbolTable(); + } + moduleSymbol.exports!.forEach((s, name) => { + if (name === InternalSymbolName.ExportEquals) return; + merged.exports!.set(name, merged.exports!.has(name) ? mergeSymbol(merged.exports!.get(name)!, s) : s); + }); + if (merged === exported) { + // We just mutated a symbol, reset any cached links we may have already set + // (Notably required to make late bound members appear) + getSymbolLinks(merged).resolvedExports = undefined; + getSymbolLinks(merged).resolvedMembers = undefined; + } + getSymbolLinks(merged).cjsExportMerged = merged; + return links.cjsExportMerged = merged; + } + + // An external module with an 'export =' declaration may be referenced as an ES6 module provided the 'export =' + // references a symbol that is at least declared as a module or a variable. The target of the 'export =' may + // combine other declarations with the module or variable (e.g. a class/module, function/module, interface/variable). + function resolveESModuleSymbol(moduleSymbol: Symbol | undefined, referencingLocation: Node, dontResolveAlias: boolean, suppressInteropError: boolean): Symbol | undefined { + const symbol = resolveExternalModuleSymbol(moduleSymbol, dontResolveAlias); + + if (!dontResolveAlias && symbol) { + if (!suppressInteropError && !(symbol.flags & (SymbolFlags.Module | SymbolFlags.Variable)) && !getDeclarationOfKind(symbol, SyntaxKind.SourceFile)) { + const compilerOptionName = moduleKind >= ModuleKind.ES2015 + ? "allowSyntheticDefaultImports" + : "esModuleInterop"; + + error(referencingLocation, Diagnostics.This_module_can_only_be_referenced_with_ECMAScript_imports_Slashexports_by_turning_on_the_0_flag_and_referencing_its_default_export, compilerOptionName); + + return symbol; + } + + const referenceParent = referencingLocation.parent; + if ( + (isImportDeclaration(referenceParent) && getNamespaceDeclarationNode(referenceParent)) || + isImportCall(referenceParent) + ) { + const reference = isImportCall(referenceParent) ? referenceParent.arguments[0] : referenceParent.moduleSpecifier; + const type = getTypeOfSymbol(symbol); + const defaultOnlyType = getTypeWithSyntheticDefaultOnly(type, symbol, moduleSymbol!, reference); + if (defaultOnlyType) { + return cloneTypeAsModuleType(symbol, defaultOnlyType, referenceParent); + } + + const targetFile = moduleSymbol?.declarations?.find(isSourceFile); + const isEsmCjsRef = targetFile && isESMFormatImportImportingCommonjsFormatFile(getUsageModeForExpression(reference), targetFile.impliedNodeFormat); + if (getESModuleInterop(compilerOptions) || isEsmCjsRef) { + let sigs = getSignaturesOfStructuredType(type, SignatureKind.Call); + if (!sigs || !sigs.length) { + sigs = getSignaturesOfStructuredType(type, SignatureKind.Construct); + } + if ( + (sigs && sigs.length) || + getPropertyOfType(type, InternalSymbolName.Default, /*skipObjectFunctionPropertyAugment*/ true) || + isEsmCjsRef + ) { + const moduleType = type.flags & TypeFlags.StructuredType + ? getTypeWithSyntheticDefaultImportType(type, symbol, moduleSymbol!, reference) + : createDefaultPropertyWrapperForModule(symbol, symbol.parent); + return cloneTypeAsModuleType(symbol, moduleType, referenceParent); + } + } + } + } + return symbol; + } + + /** + * Create a new symbol which has the module's type less the call and construct signatures + */ + function cloneTypeAsModuleType(symbol: Symbol, moduleType: Type, referenceParent: ImportDeclaration | ImportCall) { + const result = createSymbol(symbol.flags, symbol.escapedName); + result.declarations = symbol.declarations ? symbol.declarations.slice() : []; + result.parent = symbol.parent; + result.links.target = symbol; + result.links.originatingImport = referenceParent; + if (symbol.valueDeclaration) result.valueDeclaration = symbol.valueDeclaration; + if (symbol.constEnumOnlyModule) result.constEnumOnlyModule = true; + if (symbol.members) result.members = new Map(symbol.members); + if (symbol.exports) result.exports = new Map(symbol.exports); + const resolvedModuleType = resolveStructuredTypeMembers(moduleType as StructuredType); // Should already be resolved from the signature checks above + result.links.type = createAnonymousType(result, resolvedModuleType.members, emptyArray, emptyArray, resolvedModuleType.indexInfos); + return result; + } + + function hasExportAssignmentSymbol(moduleSymbol: Symbol): boolean { + return moduleSymbol.exports!.get(InternalSymbolName.ExportEquals) !== undefined; + } + + function getExportsOfModuleAsArray(moduleSymbol: Symbol): Symbol[] { + return symbolsToArray(getExportsOfModule(moduleSymbol)); + } + + function getExportsAndPropertiesOfModule(moduleSymbol: Symbol): Symbol[] { + const exports = getExportsOfModuleAsArray(moduleSymbol); + const exportEquals = resolveExternalModuleSymbol(moduleSymbol); + if (exportEquals !== moduleSymbol) { + const type = getTypeOfSymbol(exportEquals); + if (shouldTreatPropertiesOfExternalModuleAsExports(type)) { + addRange(exports, getPropertiesOfType(type)); + } + } + return exports; + } + + function forEachExportAndPropertyOfModule(moduleSymbol: Symbol, cb: (symbol: Symbol, key: __String) => void): void { + const exports = getExportsOfModule(moduleSymbol); + exports.forEach((symbol, key) => { + if (!isReservedMemberName(key)) { + cb(symbol, key); + } + }); + const exportEquals = resolveExternalModuleSymbol(moduleSymbol); + if (exportEquals !== moduleSymbol) { + const type = getTypeOfSymbol(exportEquals); + if (shouldTreatPropertiesOfExternalModuleAsExports(type)) { + forEachPropertyOfType(type, (symbol, escapedName) => { + cb(symbol, escapedName); + }); + } + } + } + + function tryGetMemberInModuleExports(memberName: __String, moduleSymbol: Symbol): Symbol | undefined { + const symbolTable = getExportsOfModule(moduleSymbol); + if (symbolTable) { + return symbolTable.get(memberName); + } + } + + function tryGetMemberInModuleExportsAndProperties(memberName: __String, moduleSymbol: Symbol): Symbol | undefined { + const symbol = tryGetMemberInModuleExports(memberName, moduleSymbol); + if (symbol) { + return symbol; + } + + const exportEquals = resolveExternalModuleSymbol(moduleSymbol); + if (exportEquals === moduleSymbol) { + return undefined; + } + + const type = getTypeOfSymbol(exportEquals); + return shouldTreatPropertiesOfExternalModuleAsExports(type) ? getPropertyOfType(type, memberName) : undefined; + } + + function shouldTreatPropertiesOfExternalModuleAsExports(resolvedExternalModuleType: Type) { + return !(resolvedExternalModuleType.flags & TypeFlags.Primitive || + getObjectFlags(resolvedExternalModuleType) & ObjectFlags.Class || + // `isArrayOrTupleLikeType` is too expensive to use in this auto-imports hot path + isArrayType(resolvedExternalModuleType) || + isTupleType(resolvedExternalModuleType)); + } + + function getExportsOfSymbol(symbol: Symbol): SymbolTable { + return symbol.flags & SymbolFlags.LateBindingContainer ? getResolvedMembersOrExportsOfSymbol(symbol, MembersOrExportsResolutionKind.resolvedExports) : + symbol.flags & SymbolFlags.Module ? getExportsOfModule(symbol) : + symbol.exports || emptySymbols; + } + + function getExportsOfModule(moduleSymbol: Symbol): SymbolTable { + const links = getSymbolLinks(moduleSymbol); + if (!links.resolvedExports) { + const { exports, typeOnlyExportStarMap } = getExportsOfModuleWorker(moduleSymbol); + links.resolvedExports = exports; + links.typeOnlyExportStarMap = typeOnlyExportStarMap; + } + return links.resolvedExports; + } + + interface ExportCollisionTracker { + specifierText: string; + exportsWithDuplicate?: ExportDeclaration[]; + } + + type ExportCollisionTrackerTable = Map<__String, ExportCollisionTracker>; + + /** + * Extends one symbol table with another while collecting information on name collisions for error message generation into the `lookupTable` argument + * Not passing `lookupTable` and `exportNode` disables this collection, and just extends the tables + */ + function extendExportSymbols(target: SymbolTable, source: SymbolTable | undefined, lookupTable?: ExportCollisionTrackerTable, exportNode?: ExportDeclaration) { + if (!source) return; + source.forEach((sourceSymbol, id) => { + if (id === InternalSymbolName.Default) return; + + const targetSymbol = target.get(id); + if (!targetSymbol) { + target.set(id, sourceSymbol); + if (lookupTable && exportNode) { + lookupTable.set(id, { + specifierText: getTextOfNode(exportNode.moduleSpecifier!), + }); + } + } + else if (lookupTable && exportNode && targetSymbol && resolveSymbol(targetSymbol) !== resolveSymbol(sourceSymbol)) { + const collisionTracker = lookupTable.get(id)!; + if (!collisionTracker.exportsWithDuplicate) { + collisionTracker.exportsWithDuplicate = [exportNode]; + } + else { + collisionTracker.exportsWithDuplicate.push(exportNode); + } + } + }); + } + + function getExportsOfModuleWorker(moduleSymbol: Symbol) { + const visitedSymbols: Symbol[] = []; + let typeOnlyExportStarMap: Map<__String, ExportDeclaration & { readonly isTypeOnly: true; readonly moduleSpecifier: Expression; }> | undefined; + const nonTypeOnlyNames = new Set<__String>(); + + // A module defined by an 'export=' consists of one export that needs to be resolved + moduleSymbol = resolveExternalModuleSymbol(moduleSymbol); + const exports = visit(moduleSymbol) || emptySymbols; + + if (typeOnlyExportStarMap) { + nonTypeOnlyNames.forEach(name => typeOnlyExportStarMap!.delete(name)); + } + + return { + exports, + typeOnlyExportStarMap, + }; + + // The ES6 spec permits export * declarations in a module to circularly reference the module itself. For example, + // module 'a' can 'export * from "b"' and 'b' can 'export * from "a"' without error. + function visit(symbol: Symbol | undefined, exportStar?: ExportDeclaration, isTypeOnly?: boolean): SymbolTable | undefined { + if (!isTypeOnly && symbol?.exports) { + // Add non-type-only names before checking if we've visited this module, + // because we might have visited it via an 'export type *', and visiting + // again with 'export *' will override the type-onlyness of its exports. + symbol.exports.forEach((_, name) => nonTypeOnlyNames.add(name)); + } + if (!(symbol && symbol.exports && pushIfUnique(visitedSymbols, symbol))) { + return; + } + const symbols = new Map(symbol.exports); + + // All export * declarations are collected in an __export symbol by the binder + const exportStars = symbol.exports.get(InternalSymbolName.ExportStar); + if (exportStars) { + const nestedSymbols = createSymbolTable(); + const lookupTable: ExportCollisionTrackerTable = new Map(); + if (exportStars.declarations) { + for (const node of exportStars.declarations) { + const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!); + const exportedSymbols = visit(resolvedModule, node as ExportDeclaration, isTypeOnly || (node as ExportDeclaration).isTypeOnly); + extendExportSymbols( + nestedSymbols, + exportedSymbols, + lookupTable, + node as ExportDeclaration, + ); + } + } + lookupTable.forEach(({ exportsWithDuplicate }, id) => { + // It's not an error if the file with multiple `export *`s with duplicate names exports a member with that name itself + if (id === "export=" || !(exportsWithDuplicate && exportsWithDuplicate.length) || symbols.has(id)) { + return; + } + for (const node of exportsWithDuplicate) { + diagnostics.add(createDiagnosticForNode( + node, + Diagnostics.Module_0_has_already_exported_a_member_named_1_Consider_explicitly_re_exporting_to_resolve_the_ambiguity, + lookupTable.get(id)!.specifierText, + unescapeLeadingUnderscores(id), + )); + } + }); + extendExportSymbols(symbols, nestedSymbols); + } + if (exportStar?.isTypeOnly) { + typeOnlyExportStarMap ??= new Map(); + symbols.forEach((_, escapedName) => + typeOnlyExportStarMap!.set( + escapedName, + exportStar as ExportDeclaration & { readonly isTypeOnly: true; readonly moduleSpecifier: Expression; }, + ) + ); + } + return symbols; + } + } + + function getMergedSymbol(symbol: Symbol): Symbol; + function getMergedSymbol(symbol: Symbol | undefined): Symbol | undefined; + function getMergedSymbol(symbol: Symbol | undefined): Symbol | undefined { + let merged: Symbol; + return symbol && symbol.mergeId && (merged = mergedSymbols[symbol.mergeId]) ? merged : symbol; + } + + function getSymbolOfDeclaration(node: Declaration): Symbol { + return getMergedSymbol(node.symbol && getLateBoundSymbol(node.symbol)); + } + + /** + * Get the merged symbol for a node. If you know the node is a `Declaration`, it is faster and more type safe to + * use use `getSymbolOfDeclaration` instead. + */ + function getSymbolOfNode(node: Node): Symbol | undefined { + return canHaveSymbol(node) ? getSymbolOfDeclaration(node) : undefined; + } + + function getParentOfSymbol(symbol: Symbol): Symbol | undefined { + return getMergedSymbol(symbol.parent && getLateBoundSymbol(symbol.parent)); + } + + function getFunctionExpressionParentSymbolOrSymbol(symbol: Symbol) { + return symbol.valueDeclaration?.kind === SyntaxKind.ArrowFunction || symbol.valueDeclaration?.kind === SyntaxKind.FunctionExpression + ? getSymbolOfNode(symbol.valueDeclaration.parent) || symbol + : symbol; + } + + function getAlternativeContainingModules(symbol: Symbol, enclosingDeclaration: Node): Symbol[] { + const containingFile = getSourceFileOfNode(enclosingDeclaration); + const id = getNodeId(containingFile); + const links = getSymbolLinks(symbol); + let results: Symbol[] | undefined; + if (links.extendedContainersByFile && (results = links.extendedContainersByFile.get(id))) { + return results; + } + if (containingFile && containingFile.imports) { + // Try to make an import using an import already in the enclosing file, if possible + for (const importRef of containingFile.imports) { + if (nodeIsSynthesized(importRef)) continue; // Synthetic names can't be resolved by `resolveExternalModuleName` - they'll cause a debug assert if they error + const resolvedModule = resolveExternalModuleName(enclosingDeclaration, importRef, /*ignoreErrors*/ true); + if (!resolvedModule) continue; + const ref = getAliasForSymbolInContainer(resolvedModule, symbol); + if (!ref) continue; + results = append(results, resolvedModule); + } + if (length(results)) { + (links.extendedContainersByFile || (links.extendedContainersByFile = new Map())).set(id, results!); + return results!; + } + } + if (links.extendedContainers) { + return links.extendedContainers; + } + // No results from files already being imported by this file - expand search (expensive, but not location-specific, so cached) + const otherFiles = host.getSourceFiles(); + for (const file of otherFiles) { + if (!isExternalModule(file)) continue; + const sym = getSymbolOfDeclaration(file); + const ref = getAliasForSymbolInContainer(sym, symbol); + if (!ref) continue; + results = append(results, sym); + } + return links.extendedContainers = results || emptyArray; + } + + /** + * Attempts to find the symbol corresponding to the container a symbol is in - usually this + * is just its' `.parent`, but for locals, this value is `undefined` + */ + function getContainersOfSymbol(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags): Symbol[] | undefined { + const container = getParentOfSymbol(symbol); + // Type parameters end up in the `members` lists but are not externally visible + if (container && !(symbol.flags & SymbolFlags.TypeParameter)) { + return getWithAlternativeContainers(container); + } + const candidates = mapDefined(symbol.declarations, d => { + if (!isAmbientModule(d) && d.parent) { + // direct children of a module + if (hasNonGlobalAugmentationExternalModuleSymbol(d.parent)) { + return getSymbolOfDeclaration(d.parent as Declaration); + } + // export ='d member of an ambient module + if (isModuleBlock(d.parent) && d.parent.parent && resolveExternalModuleSymbol(getSymbolOfDeclaration(d.parent.parent)) === symbol) { + return getSymbolOfDeclaration(d.parent.parent); + } + } + if (isClassExpression(d) && isBinaryExpression(d.parent) && d.parent.operatorToken.kind === SyntaxKind.EqualsToken && isAccessExpression(d.parent.left) && isEntityNameExpression(d.parent.left.expression)) { + if (isModuleExportsAccessExpression(d.parent.left) || isExportsIdentifier(d.parent.left.expression)) { + return getSymbolOfDeclaration(getSourceFileOfNode(d)); + } + checkExpressionCached(d.parent.left.expression); + return getNodeLinks(d.parent.left.expression).resolvedSymbol; + } + }); + if (!length(candidates)) { + return undefined; + } + const containers = mapDefined(candidates, candidate => getAliasForSymbolInContainer(candidate, symbol) ? candidate : undefined); + + let bestContainers: Symbol[] = []; + let alternativeContainers: Symbol[] = []; + + for (const container of containers) { + const [bestMatch, ...rest] = getWithAlternativeContainers(container); + bestContainers = append(bestContainers, bestMatch); + alternativeContainers = addRange(alternativeContainers, rest); + } + + return concatenate(bestContainers, alternativeContainers); + + function getWithAlternativeContainers(container: Symbol) { + const additionalContainers = mapDefined(container.declarations, fileSymbolIfFileSymbolExportEqualsContainer); + const reexportContainers = enclosingDeclaration && getAlternativeContainingModules(symbol, enclosingDeclaration); + const objectLiteralContainer = getVariableDeclarationOfObjectLiteral(container, meaning); + if ( + enclosingDeclaration && + container.flags & getQualifiedLeftMeaning(meaning) && + getAccessibleSymbolChain(container, enclosingDeclaration, SymbolFlags.Namespace, /*useOnlyExternalAliasing*/ false) + ) { + return append(concatenate(concatenate([container], additionalContainers), reexportContainers), objectLiteralContainer); // This order expresses a preference for the real container if it is in scope + } + // we potentially have a symbol which is a member of the instance side of something - look for a variable in scope with the container's type + // which may be acting like a namespace (eg, `Symbol` acts like a namespace when looking up `Symbol.toStringTag`) + const firstVariableMatch = !(container.flags & getQualifiedLeftMeaning(meaning)) + && container.flags & SymbolFlags.Type + && getDeclaredTypeOfSymbol(container).flags & TypeFlags.Object + && meaning === SymbolFlags.Value + ? forEachSymbolTableInScope(enclosingDeclaration, t => { + return forEachEntry(t, s => { + if (s.flags & getQualifiedLeftMeaning(meaning) && getTypeOfSymbol(s) === getDeclaredTypeOfSymbol(container)) { + return s; + } + }); + }) : undefined; + let res = firstVariableMatch ? [firstVariableMatch, ...additionalContainers, container] : [...additionalContainers, container]; + res = append(res, objectLiteralContainer); + res = addRange(res, reexportContainers); + return res; + } + + function fileSymbolIfFileSymbolExportEqualsContainer(d: Declaration) { + return container && getFileSymbolIfFileSymbolExportEqualsContainer(d, container); + } + } + + function getVariableDeclarationOfObjectLiteral(symbol: Symbol, meaning: SymbolFlags) { + // If we're trying to reference some object literal in, eg `var a = { x: 1 }`, the symbol for the literal, `__object`, is distinct + // from the symbol of the declaration it is being assigned to. Since we can use the declaration to refer to the literal, however, + // we'd like to make that connection here - potentially causing us to paint the declaration's visibility, and therefore the literal. + const firstDecl: Node | false = !!length(symbol.declarations) && first(symbol.declarations!); + if (meaning & SymbolFlags.Value && firstDecl && firstDecl.parent && isVariableDeclaration(firstDecl.parent)) { + if (isObjectLiteralExpression(firstDecl) && firstDecl === firstDecl.parent.initializer || isTypeLiteralNode(firstDecl) && firstDecl === firstDecl.parent.type) { + return getSymbolOfDeclaration(firstDecl.parent); + } + } + } + + function getFileSymbolIfFileSymbolExportEqualsContainer(d: Declaration, container: Symbol) { + const fileSymbol = getExternalModuleContainer(d); + const exported = fileSymbol && fileSymbol.exports && fileSymbol.exports.get(InternalSymbolName.ExportEquals); + return exported && getSymbolIfSameReference(exported, container) ? fileSymbol : undefined; + } + + function getAliasForSymbolInContainer(container: Symbol, symbol: Symbol) { + if (container === getParentOfSymbol(symbol)) { + // fast path, `symbol` is either already the alias or isn't aliased + return symbol; + } + // Check if container is a thing with an `export=` which points directly at `symbol`, and if so, return + // the container itself as the alias for the symbol + const exportEquals = container.exports && container.exports.get(InternalSymbolName.ExportEquals); + if (exportEquals && getSymbolIfSameReference(exportEquals, symbol)) { + return container; + } + const exports = getExportsOfSymbol(container); + const quick = exports.get(symbol.escapedName); + if (quick && getSymbolIfSameReference(quick, symbol)) { + return quick; + } + return forEachEntry(exports, exported => { + if (getSymbolIfSameReference(exported, symbol)) { + return exported; + } + }); + } + + /** + * Checks if two symbols, through aliasing and/or merging, refer to the same thing + */ + function getSymbolIfSameReference(s1: Symbol, s2: Symbol) { + if (getMergedSymbol(resolveSymbol(getMergedSymbol(s1))) === getMergedSymbol(resolveSymbol(getMergedSymbol(s2)))) { + return s1; + } + } + + function getExportSymbolOfValueSymbolIfExported(symbol: Symbol): Symbol; + function getExportSymbolOfValueSymbolIfExported(symbol: Symbol | undefined): Symbol | undefined; + function getExportSymbolOfValueSymbolIfExported(symbol: Symbol | undefined): Symbol | undefined { + return getMergedSymbol(symbol && (symbol.flags & SymbolFlags.ExportValue) !== 0 && symbol.exportSymbol || symbol); + } + + function symbolIsValue(symbol: Symbol, includeTypeOnlyMembers?: boolean): boolean { + return !!( + symbol.flags & SymbolFlags.Value || + symbol.flags & SymbolFlags.Alias && getSymbolFlags(symbol, !includeTypeOnlyMembers) & SymbolFlags.Value + ); + } + + function createType(flags: TypeFlags): Type { + const result = new Type(checker, flags); + typeCount++; + result.id = typeCount; + tracing?.recordType(result); + return result; + } + + function createTypeWithSymbol(flags: TypeFlags, symbol: Symbol): Type { + const result = createType(flags); + result.symbol = symbol; + return result; + } + + function createOriginType(flags: TypeFlags): Type { + return new Type(checker, flags); + } + + function createIntrinsicType(kind: TypeFlags, intrinsicName: string, objectFlags = ObjectFlags.None, debugIntrinsicName?: string): IntrinsicType { + checkIntrinsicName(intrinsicName, debugIntrinsicName); + const type = createType(kind) as IntrinsicType; + type.intrinsicName = intrinsicName; + type.debugIntrinsicName = debugIntrinsicName; + type.objectFlags = objectFlags | ObjectFlags.CouldContainTypeVariablesComputed | ObjectFlags.IsGenericTypeComputed | ObjectFlags.IsUnknownLikeUnionComputed | ObjectFlags.IsNeverIntersectionComputed; + return type; + } + + function checkIntrinsicName(name: string, debug: string | undefined) { + const key = `${name},${debug ?? ""}`; + if (seenIntrinsicNames.has(key)) { + Debug.fail(`Duplicate intrinsic type name ${name}${debug ? ` (${debug})` : ""}; you may need to pass a name to createIntrinsicType.`); + } + seenIntrinsicNames.add(key); + } + + function createObjectType(objectFlags: ObjectFlags, symbol?: Symbol): ObjectType { + const type = createTypeWithSymbol(TypeFlags.Object, symbol!) as ObjectType; + type.objectFlags = objectFlags; + type.members = undefined; + type.properties = undefined; + type.callSignatures = undefined; + type.constructSignatures = undefined; + type.indexInfos = undefined; + return type; + } + + function createTypeofType() { + return getUnionType(arrayFrom(typeofNEFacts.keys(), getStringLiteralType)); + } + + function createTypeParameter(symbol?: Symbol) { + return createTypeWithSymbol(TypeFlags.TypeParameter, symbol!) as TypeParameter; + } + + // A reserved member name starts with two underscores, but the third character cannot be an underscore, + // @, or #. A third underscore indicates an escaped form of an identifier that started + // with at least two underscores. The @ character indicates that the name is denoted by a well known ES + // Symbol instance and the # character indicates that the name is a PrivateIdentifier. + function isReservedMemberName(name: __String) { + return (name as string).charCodeAt(0) === CharacterCodes._ && + (name as string).charCodeAt(1) === CharacterCodes._ && + (name as string).charCodeAt(2) !== CharacterCodes._ && + (name as string).charCodeAt(2) !== CharacterCodes.at && + (name as string).charCodeAt(2) !== CharacterCodes.hash; + } + + function getNamedMembers(members: SymbolTable): Symbol[] { + let result: Symbol[] | undefined; + members.forEach((symbol, id) => { + if (isNamedMember(symbol, id)) { + (result || (result = [])).push(symbol); + } + }); + return result || emptyArray; + } + + function isNamedMember(member: Symbol, escapedName: __String) { + return !isReservedMemberName(escapedName) && symbolIsValue(member); + } + + function getNamedOrIndexSignatureMembers(members: SymbolTable): Symbol[] { + const result = getNamedMembers(members); + const index = getIndexSymbolFromSymbolTable(members); + return index ? concatenate(result, [index]) : result; + } + + function setStructuredTypeMembers(type: StructuredType, members: SymbolTable, callSignatures: readonly Signature[], constructSignatures: readonly Signature[], indexInfos: readonly IndexInfo[]): ResolvedType { + const resolved = type as ResolvedType; + resolved.members = members; + resolved.properties = emptyArray; + resolved.callSignatures = callSignatures; + resolved.constructSignatures = constructSignatures; + resolved.indexInfos = indexInfos; + // This can loop back to getPropertyOfType() which would crash if `callSignatures` & `constructSignatures` are not initialized. + if (members !== emptySymbols) resolved.properties = getNamedMembers(members); + return resolved; + } + + function createAnonymousType(symbol: Symbol | undefined, members: SymbolTable, callSignatures: readonly Signature[], constructSignatures: readonly Signature[], indexInfos: readonly IndexInfo[]): ResolvedType { + return setStructuredTypeMembers(createObjectType(ObjectFlags.Anonymous, symbol), members, callSignatures, constructSignatures, indexInfos); + } + + function getResolvedTypeWithoutAbstractConstructSignatures(type: ResolvedType) { + if (type.constructSignatures.length === 0) return type; + if (type.objectTypeWithoutAbstractConstructSignatures) return type.objectTypeWithoutAbstractConstructSignatures; + const constructSignatures = filter(type.constructSignatures, signature => !(signature.flags & SignatureFlags.Abstract)); + if (type.constructSignatures === constructSignatures) return type; + const typeCopy = createAnonymousType( + type.symbol, + type.members, + type.callSignatures, + some(constructSignatures) ? constructSignatures : emptyArray, + type.indexInfos, + ); + type.objectTypeWithoutAbstractConstructSignatures = typeCopy; + typeCopy.objectTypeWithoutAbstractConstructSignatures = typeCopy; + return typeCopy; + } + + function forEachSymbolTableInScope(enclosingDeclaration: Node | undefined, callback: (symbolTable: SymbolTable, ignoreQualification?: boolean, isLocalNameLookup?: boolean, scopeNode?: Node) => T): T { + let result: T; + for (let location = enclosingDeclaration; location; location = location.parent) { + // Locals of a source file are not in scope (because they get merged into the global symbol table) + if (canHaveLocals(location) && location.locals && !isGlobalSourceFile(location)) { + if (result = callback(location.locals, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true, location)) { + return result; + } + } + switch (location.kind) { + case SyntaxKind.SourceFile: + if (!isExternalOrCommonJsModule(location as SourceFile)) { + break; + } + // falls through + case SyntaxKind.ModuleDeclaration: + const sym = getSymbolOfDeclaration(location as ModuleDeclaration); + // `sym` may not have exports if this module declaration is backed by the symbol for a `const` that's being rewritten + // into a namespace - in such cases, it's best to just let the namespace appear empty (the const members couldn't have referred + // to one another anyway) + if (result = callback(sym?.exports || emptySymbols, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true, location)) { + return result; + } + break; + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + case SyntaxKind.InterfaceDeclaration: + // Type parameters are bound into `members` lists so they can merge across declarations + // This is troublesome, since in all other respects, they behave like locals :cries: + // TODO: the below is shared with similar code in `resolveName` - in fact, rephrasing all this symbol + // lookup logic in terms of `resolveName` would be nice + // The below is used to lookup type parameters within a class or interface, as they are added to the class/interface locals + // These can never be latebound, so the symbol's raw members are sufficient. `getMembersOfNode` cannot be used, as it would + // trigger resolving late-bound names, which we may already be in the process of doing while we're here! + let table: Map<__String, Symbol> | undefined; + // TODO: Should this filtered table be cached in some way? + (getSymbolOfDeclaration(location as ClassLikeDeclaration | InterfaceDeclaration).members || emptySymbols).forEach((memberSymbol, key) => { + if (memberSymbol.flags & (SymbolFlags.Type & ~SymbolFlags.Assignment)) { + (table || (table = createSymbolTable())).set(key, memberSymbol); + } + }); + if (table && (result = callback(table, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ false, location))) { + return result; + } + break; + } + } + + return callback(globals, /*ignoreQualification*/ undefined, /*isLocalNameLookup*/ true); + } + + function getQualifiedLeftMeaning(rightMeaning: SymbolFlags) { + // If we are looking in value space, the parent meaning is value, other wise it is namespace + return rightMeaning === SymbolFlags.Value ? SymbolFlags.Value : SymbolFlags.Namespace; + } + + function getAccessibleSymbolChain(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, useOnlyExternalAliasing: boolean, visitedSymbolTablesMap = new Map()): Symbol[] | undefined { + if (!(symbol && !isPropertyOrMethodDeclarationSymbol(symbol))) { + return undefined; + } + const links = getSymbolLinks(symbol); + const cache = (links.accessibleChainCache ||= new Map()); + // Go from enclosingDeclaration to the first scope we check, so the cache is keyed off the scope and thus shared more + const firstRelevantLocation = forEachSymbolTableInScope(enclosingDeclaration, (_, __, ___, node) => node); + const key = `${useOnlyExternalAliasing ? 0 : 1}|${firstRelevantLocation && getNodeId(firstRelevantLocation)}|${meaning}`; + if (cache.has(key)) { + return cache.get(key); + } + + const id = getSymbolId(symbol); + let visitedSymbolTables = visitedSymbolTablesMap.get(id); + if (!visitedSymbolTables) { + visitedSymbolTablesMap.set(id, visitedSymbolTables = []); + } + const result = forEachSymbolTableInScope(enclosingDeclaration, getAccessibleSymbolChainFromSymbolTable); + cache.set(key, result); + return result; + + /** + * @param {ignoreQualification} boolean Set when a symbol is being looked for through the exports of another symbol (meaning we have a route to qualify it already) + */ + function getAccessibleSymbolChainFromSymbolTable(symbols: SymbolTable, ignoreQualification?: boolean, isLocalNameLookup?: boolean): Symbol[] | undefined { + if (!pushIfUnique(visitedSymbolTables!, symbols)) { + return undefined; + } + + const result = trySymbolTable(symbols, ignoreQualification, isLocalNameLookup); + visitedSymbolTables!.pop(); + return result; + } + + function canQualifySymbol(symbolFromSymbolTable: Symbol, meaning: SymbolFlags) { + // If the symbol is equivalent and doesn't need further qualification, this symbol is accessible + return !needsQualification(symbolFromSymbolTable, enclosingDeclaration, meaning) || + // If symbol needs qualification, make sure that parent is accessible, if it is then this symbol is accessible too + !!getAccessibleSymbolChain(symbolFromSymbolTable.parent, enclosingDeclaration, getQualifiedLeftMeaning(meaning), useOnlyExternalAliasing, visitedSymbolTablesMap); + } + + function isAccessible(symbolFromSymbolTable: Symbol, resolvedAliasSymbol?: Symbol, ignoreQualification?: boolean) { + return (symbol === (resolvedAliasSymbol || symbolFromSymbolTable) || getMergedSymbol(symbol) === getMergedSymbol(resolvedAliasSymbol || symbolFromSymbolTable)) && + // if the symbolFromSymbolTable is not external module (it could be if it was determined as ambient external module and would be in globals table) + // and if symbolFromSymbolTable or alias resolution matches the symbol, + // check the symbol can be qualified, it is only then this symbol is accessible + !some(symbolFromSymbolTable.declarations, hasNonGlobalAugmentationExternalModuleSymbol) && + (ignoreQualification || canQualifySymbol(getMergedSymbol(symbolFromSymbolTable), meaning)); + } + + function trySymbolTable(symbols: SymbolTable, ignoreQualification: boolean | undefined, isLocalNameLookup: boolean | undefined): Symbol[] | undefined { + // If symbol is directly available by its name in the symbol table + if (isAccessible(symbols.get(symbol!.escapedName)!, /*resolvedAliasSymbol*/ undefined, ignoreQualification)) { + return [symbol!]; + } + + // Check if symbol is any of the aliases in scope + const result = forEachEntry(symbols, symbolFromSymbolTable => { + if ( + symbolFromSymbolTable.flags & SymbolFlags.Alias + && symbolFromSymbolTable.escapedName !== InternalSymbolName.ExportEquals + && symbolFromSymbolTable.escapedName !== InternalSymbolName.Default + && !(isUMDExportSymbol(symbolFromSymbolTable) && enclosingDeclaration && isExternalModule(getSourceFileOfNode(enclosingDeclaration))) + // If `!useOnlyExternalAliasing`, we can use any type of alias to get the name + && (!useOnlyExternalAliasing || some(symbolFromSymbolTable.declarations, isExternalModuleImportEqualsDeclaration)) + // If we're looking up a local name to reference directly, omit namespace reexports, otherwise when we're trawling through an export list to make a dotted name, we can keep it + && (isLocalNameLookup ? !some(symbolFromSymbolTable.declarations, isNamespaceReexportDeclaration) : true) + // While exports are generally considered to be in scope, export-specifier declared symbols are _not_ + // See similar comment in `resolveName` for details + && (ignoreQualification || !getDeclarationOfKind(symbolFromSymbolTable, SyntaxKind.ExportSpecifier)) + ) { + const resolvedImportedSymbol = resolveAlias(symbolFromSymbolTable); + const candidate = getCandidateListForSymbol(symbolFromSymbolTable, resolvedImportedSymbol, ignoreQualification); + if (candidate) { + return candidate; + } + } + if (symbolFromSymbolTable.escapedName === symbol!.escapedName && symbolFromSymbolTable.exportSymbol) { + if (isAccessible(getMergedSymbol(symbolFromSymbolTable.exportSymbol), /*resolvedAliasSymbol*/ undefined, ignoreQualification)) { + return [symbol!]; + } + } + }); + + // If there's no result and we're looking at the global symbol table, treat `globalThis` like an alias and try to lookup thru that + return result || (symbols === globals ? getCandidateListForSymbol(globalThisSymbol, globalThisSymbol, ignoreQualification) : undefined); + } + + function getCandidateListForSymbol(symbolFromSymbolTable: Symbol, resolvedImportedSymbol: Symbol, ignoreQualification: boolean | undefined) { + if (isAccessible(symbolFromSymbolTable, resolvedImportedSymbol, ignoreQualification)) { + return [symbolFromSymbolTable]; + } + + // Look in the exported members, if we can find accessibleSymbolChain, symbol is accessible using this chain + // but only if the symbolFromSymbolTable can be qualified + const candidateTable = getExportsOfSymbol(resolvedImportedSymbol); + const accessibleSymbolsFromExports = candidateTable && getAccessibleSymbolChainFromSymbolTable(candidateTable, /*ignoreQualification*/ true); + if (accessibleSymbolsFromExports && canQualifySymbol(symbolFromSymbolTable, getQualifiedLeftMeaning(meaning))) { + return [symbolFromSymbolTable].concat(accessibleSymbolsFromExports); + } + } + } + + function needsQualification(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags) { + let qualify = false; + forEachSymbolTableInScope(enclosingDeclaration, symbolTable => { + // If symbol of this name is not available in the symbol table we are ok + let symbolFromSymbolTable = getMergedSymbol(symbolTable.get(symbol.escapedName)); + if (!symbolFromSymbolTable) { + // Continue to the next symbol table + return false; + } + // If the symbol with this name is present it should refer to the symbol + if (symbolFromSymbolTable === symbol) { + // No need to qualify + return true; + } + + // Qualify if the symbol from symbol table has same meaning as expected + const shouldResolveAlias = symbolFromSymbolTable.flags & SymbolFlags.Alias && !getDeclarationOfKind(symbolFromSymbolTable, SyntaxKind.ExportSpecifier); + symbolFromSymbolTable = shouldResolveAlias ? resolveAlias(symbolFromSymbolTable) : symbolFromSymbolTable; + const flags = shouldResolveAlias ? getSymbolFlags(symbolFromSymbolTable) : symbolFromSymbolTable.flags; + if (flags & meaning) { + qualify = true; + return true; + } + + // Continue to the next symbol table + return false; + }); + + return qualify; + } + + function isPropertyOrMethodDeclarationSymbol(symbol: Symbol) { + if (symbol.declarations && symbol.declarations.length) { + for (const declaration of symbol.declarations) { + switch (declaration.kind) { + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + continue; + default: + return false; + } + } + return true; + } + return false; + } + + function isTypeSymbolAccessible(typeSymbol: Symbol, enclosingDeclaration: Node | undefined): boolean { + const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, SymbolFlags.Type, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ true); + return access.accessibility === SymbolAccessibility.Accessible; + } + + function isValueSymbolAccessible(typeSymbol: Symbol, enclosingDeclaration: Node | undefined): boolean { + const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, SymbolFlags.Value, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ true); + return access.accessibility === SymbolAccessibility.Accessible; + } + + function isSymbolAccessibleByFlags(typeSymbol: Symbol, enclosingDeclaration: Node | undefined, flags: SymbolFlags): boolean { + const access = isSymbolAccessibleWorker(typeSymbol, enclosingDeclaration, flags, /*shouldComputeAliasesToMakeVisible*/ false, /*allowModules*/ false); + return access.accessibility === SymbolAccessibility.Accessible; + } + + function isAnySymbolAccessible(symbols: Symbol[] | undefined, enclosingDeclaration: Node | undefined, initialSymbol: Symbol, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean, allowModules: boolean): SymbolAccessibilityResult | undefined { + if (!length(symbols)) return; + + let hadAccessibleChain: Symbol | undefined; + let earlyModuleBail = false; + for (const symbol of symbols!) { + // Symbol is accessible if it by itself is accessible + const accessibleSymbolChain = getAccessibleSymbolChain(symbol, enclosingDeclaration, meaning, /*useOnlyExternalAliasing*/ false); + if (accessibleSymbolChain) { + hadAccessibleChain = symbol; + const hasAccessibleDeclarations = hasVisibleDeclarations(accessibleSymbolChain[0], shouldComputeAliasesToMakeVisible); + if (hasAccessibleDeclarations) { + return hasAccessibleDeclarations; + } + } + if (allowModules) { + if (some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + if (shouldComputeAliasesToMakeVisible) { + earlyModuleBail = true; + // Generally speaking, we want to use the aliases that already exist to refer to a module, if present + // In order to do so, we need to find those aliases in order to retain them in declaration emit; so + // if we are in declaration emit, we cannot use the fast path for module visibility until we've exhausted + // all other visibility options (in order to capture the possible aliases used to reference the module) + continue; + } + // Any meaning of a module symbol is always accessible via an `import` type + return { + accessibility: SymbolAccessibility.Accessible, + }; + } + } + + // If we haven't got the accessible symbol, it doesn't mean the symbol is actually inaccessible. + // It could be a qualified symbol and hence verify the path + // e.g.: + // module m { + // export class c { + // } + // } + // const x: typeof m.c + // In the above example when we start with checking if typeof m.c symbol is accessible, + // we are going to see if c can be accessed in scope directly. + // But it can't, hence the accessible is going to be undefined, but that doesn't mean m.c is inaccessible + // It is accessible if the parent m is accessible because then m.c can be accessed through qualification + + const containers = getContainersOfSymbol(symbol, enclosingDeclaration, meaning); + const parentResult = isAnySymbolAccessible(containers, enclosingDeclaration, initialSymbol, initialSymbol === symbol ? getQualifiedLeftMeaning(meaning) : meaning, shouldComputeAliasesToMakeVisible, allowModules); + if (parentResult) { + return parentResult; + } + } + + if (earlyModuleBail) { + return { + accessibility: SymbolAccessibility.Accessible, + }; + } + + if (hadAccessibleChain) { + return { + accessibility: SymbolAccessibility.NotAccessible, + errorSymbolName: symbolToString(initialSymbol, enclosingDeclaration, meaning), + errorModuleName: hadAccessibleChain !== initialSymbol ? symbolToString(hadAccessibleChain, enclosingDeclaration, SymbolFlags.Namespace) : undefined, + }; + } + } + + /** + * Check if the given symbol in given enclosing declaration is accessible and mark all associated alias to be visible if requested + * + * @param symbol a Symbol to check if accessible + * @param enclosingDeclaration a Node containing reference to the symbol + * @param meaning a SymbolFlags to check if such meaning of the symbol is accessible + * @param shouldComputeAliasToMakeVisible a boolean value to indicate whether to return aliases to be mark visible in case the symbol is accessible + */ + function isSymbolAccessible(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean): SymbolAccessibilityResult { + return isSymbolAccessibleWorker(symbol, enclosingDeclaration, meaning, shouldComputeAliasesToMakeVisible, /*allowModules*/ true); + } + + function isSymbolAccessibleWorker(symbol: Symbol | undefined, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, shouldComputeAliasesToMakeVisible: boolean, allowModules: boolean): SymbolAccessibilityResult { + if (symbol && enclosingDeclaration) { + const result = isAnySymbolAccessible([symbol], enclosingDeclaration, symbol, meaning, shouldComputeAliasesToMakeVisible, allowModules); + if (result) { + return result; + } + + // This could be a symbol that is not exported in the external module + // or it could be a symbol from different external module that is not aliased and hence cannot be named + const symbolExternalModule = forEach(symbol.declarations, getExternalModuleContainer); + if (symbolExternalModule) { + const enclosingExternalModule = getExternalModuleContainer(enclosingDeclaration); + if (symbolExternalModule !== enclosingExternalModule) { + // name from different external module that is not visible + return { + accessibility: SymbolAccessibility.CannotBeNamed, + errorSymbolName: symbolToString(symbol, enclosingDeclaration, meaning), + errorModuleName: symbolToString(symbolExternalModule), + errorNode: isInJSFile(enclosingDeclaration) ? enclosingDeclaration : undefined, + }; + } + } + + // Just a local name that is not accessible + return { + accessibility: SymbolAccessibility.NotAccessible, + errorSymbolName: symbolToString(symbol, enclosingDeclaration, meaning), + }; + } + + return { accessibility: SymbolAccessibility.Accessible }; + } + + function getExternalModuleContainer(declaration: Node) { + const node = findAncestor(declaration, hasExternalModuleSymbol); + return node && getSymbolOfDeclaration(node as AmbientModuleDeclaration | SourceFile); + } + + function hasExternalModuleSymbol(declaration: Node) { + return isAmbientModule(declaration) || (declaration.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(declaration as SourceFile)); + } + + function hasNonGlobalAugmentationExternalModuleSymbol(declaration: Node) { + return isModuleWithStringLiteralName(declaration) || (declaration.kind === SyntaxKind.SourceFile && isExternalOrCommonJsModule(declaration as SourceFile)); + } + + function hasVisibleDeclarations(symbol: Symbol, shouldComputeAliasToMakeVisible: boolean): SymbolVisibilityResult | undefined { + let aliasesToMakeVisible: LateVisibilityPaintedStatement[] | undefined; + if (!every(filter(symbol.declarations, d => d.kind !== SyntaxKind.Identifier), getIsDeclarationVisible)) { + return undefined; + } + return { accessibility: SymbolAccessibility.Accessible, aliasesToMakeVisible }; + + function getIsDeclarationVisible(declaration: Declaration) { + if (!isDeclarationVisible(declaration)) { + // Mark the unexported alias as visible if its parent is visible + // because these kind of aliases can be used to name types in declaration file + + const anyImportSyntax = getAnyImportSyntax(declaration); + if ( + anyImportSyntax && + !hasSyntacticModifier(anyImportSyntax, ModifierFlags.Export) && // import clause without export + isDeclarationVisible(anyImportSyntax.parent) + ) { + return addVisibleAlias(declaration, anyImportSyntax); + } + else if ( + isVariableDeclaration(declaration) && isVariableStatement(declaration.parent.parent) && + !hasSyntacticModifier(declaration.parent.parent, ModifierFlags.Export) && // unexported variable statement + isDeclarationVisible(declaration.parent.parent.parent) + ) { + return addVisibleAlias(declaration, declaration.parent.parent); + } + else if ( + isLateVisibilityPaintedStatement(declaration) // unexported top-level statement + && !hasSyntacticModifier(declaration, ModifierFlags.Export) + && isDeclarationVisible(declaration.parent) + ) { + return addVisibleAlias(declaration, declaration); + } + else if (isBindingElement(declaration)) { + if ( + symbol.flags & SymbolFlags.Alias && isInJSFile(declaration) && declaration.parent?.parent // exported import-like top-level JS require statement + && isVariableDeclaration(declaration.parent.parent) + && declaration.parent.parent.parent?.parent && isVariableStatement(declaration.parent.parent.parent.parent) + && !hasSyntacticModifier(declaration.parent.parent.parent.parent, ModifierFlags.Export) + && declaration.parent.parent.parent.parent.parent // check if the thing containing the variable statement is visible (ie, the file) + && isDeclarationVisible(declaration.parent.parent.parent.parent.parent) + ) { + return addVisibleAlias(declaration, declaration.parent.parent.parent.parent); + } + else if (symbol.flags & SymbolFlags.BlockScopedVariable) { + const variableStatement = findAncestor(declaration, isVariableStatement)!; + if (hasSyntacticModifier(variableStatement, ModifierFlags.Export)) { + return true; + } + if (!isDeclarationVisible(variableStatement.parent)) { + return false; + } + return addVisibleAlias(declaration, variableStatement); + } + } + + // Declaration is not visible + return false; + } + + return true; + } + + function addVisibleAlias(declaration: Declaration, aliasingStatement: LateVisibilityPaintedStatement) { + // In function "buildTypeDisplay" where we decide whether to write type-alias or serialize types, + // we want to just check if type- alias is accessible or not but we don't care about emitting those alias at that time + // since we will do the emitting later in trackSymbol. + if (shouldComputeAliasToMakeVisible) { + getNodeLinks(declaration).isVisible = true; + aliasesToMakeVisible = appendIfUnique(aliasesToMakeVisible, aliasingStatement); + } + return true; + } + } + + function getMeaningOfEntityNameReference(entityName: EntityNameOrEntityNameExpression): SymbolFlags { + // get symbol of the first identifier of the entityName + let meaning: SymbolFlags; + if ( + entityName.parent.kind === SyntaxKind.TypeQuery || + entityName.parent.kind === SyntaxKind.ExpressionWithTypeArguments && !isPartOfTypeNode(entityName.parent) || + entityName.parent.kind === SyntaxKind.ComputedPropertyName || + entityName.parent.kind === SyntaxKind.TypePredicate && (entityName.parent as TypePredicateNode).parameterName === entityName + ) { + // Typeof value + meaning = SymbolFlags.Value | SymbolFlags.ExportValue; + } + else if ( + entityName.kind === SyntaxKind.QualifiedName || entityName.kind === SyntaxKind.PropertyAccessExpression || + entityName.parent.kind === SyntaxKind.ImportEqualsDeclaration || + (entityName.parent.kind === SyntaxKind.QualifiedName && (entityName.parent as QualifiedName).left === entityName) || + (entityName.parent.kind === SyntaxKind.PropertyAccessExpression && (entityName.parent as PropertyAccessExpression).expression === entityName) || + (entityName.parent.kind === SyntaxKind.ElementAccessExpression && (entityName.parent as ElementAccessExpression).expression === entityName) + ) { + // Left identifier from type reference or TypeAlias + // Entity name of the import declaration + meaning = SymbolFlags.Namespace; + } + else { + // Type Reference or TypeAlias entity = Identifier + meaning = SymbolFlags.Type; + } + return meaning; + } + + function isEntityNameVisible(entityName: EntityNameOrEntityNameExpression, enclosingDeclaration: Node, shouldComputeAliasToMakeVisible = true): SymbolVisibilityResult { + const meaning = getMeaningOfEntityNameReference(entityName); + const firstIdentifier = getFirstIdentifier(entityName); + const symbol = resolveName(enclosingDeclaration, firstIdentifier.escapedText, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (symbol && symbol.flags & SymbolFlags.TypeParameter && meaning & SymbolFlags.Type) { + return { accessibility: SymbolAccessibility.Accessible }; + } + if (!symbol && isThisIdentifier(firstIdentifier) && isSymbolAccessible(getSymbolOfDeclaration(getThisContainer(firstIdentifier, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)), firstIdentifier, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility === SymbolAccessibility.Accessible) { + return { accessibility: SymbolAccessibility.Accessible }; + } + + if (!symbol) { + return { + accessibility: SymbolAccessibility.NotResolved, + errorSymbolName: getTextOfNode(firstIdentifier), + errorNode: firstIdentifier, + }; + } + // Verify if the symbol is accessible + return hasVisibleDeclarations(symbol, shouldComputeAliasToMakeVisible) || { + accessibility: SymbolAccessibility.NotAccessible, + errorSymbolName: getTextOfNode(firstIdentifier), + errorNode: firstIdentifier, + }; + } + + function symbolToString(symbol: Symbol, enclosingDeclaration?: Node, meaning?: SymbolFlags, flags: SymbolFormatFlags = SymbolFormatFlags.AllowAnyNodeKind, writer?: EmitTextWriter): string { + let nodeFlags = NodeBuilderFlags.IgnoreErrors; + if (flags & SymbolFormatFlags.UseOnlyExternalAliasing) { + nodeFlags |= NodeBuilderFlags.UseOnlyExternalAliasing; + } + if (flags & SymbolFormatFlags.WriteTypeParametersOrArguments) { + nodeFlags |= NodeBuilderFlags.WriteTypeParametersInQualifiedName; + } + if (flags & SymbolFormatFlags.UseAliasDefinedOutsideCurrentScope) { + nodeFlags |= NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope; + } + if (flags & SymbolFormatFlags.DoNotIncludeSymbolChain) { + nodeFlags |= NodeBuilderFlags.DoNotIncludeSymbolChain; + } + if (flags & SymbolFormatFlags.WriteComputedProps) { + nodeFlags |= NodeBuilderFlags.WriteComputedProps; + } + const builder = flags & SymbolFormatFlags.AllowAnyNodeKind ? nodeBuilder.symbolToNode : nodeBuilder.symbolToEntityName; + return writer ? symbolToStringWorker(writer).getText() : usingSingleLineStringWriter(symbolToStringWorker); + + function symbolToStringWorker(writer: EmitTextWriter) { + const entity = builder(symbol, meaning!, enclosingDeclaration, nodeFlags)!; // TODO: GH#18217 + // add neverAsciiEscape for GH#39027 + const printer = enclosingDeclaration?.kind === SyntaxKind.SourceFile + ? createPrinterWithRemoveCommentsNeverAsciiEscape() + : createPrinterWithRemoveComments(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, entity, /*sourceFile*/ sourceFile, writer); + return writer; + } + } + + function signatureToString(signature: Signature, enclosingDeclaration?: Node, flags = TypeFormatFlags.None, kind?: SignatureKind, writer?: EmitTextWriter): string { + return writer ? signatureToStringWorker(writer).getText() : usingSingleLineStringWriter(signatureToStringWorker); + + function signatureToStringWorker(writer: EmitTextWriter) { + let sigOutput: SyntaxKind; + if (flags & TypeFormatFlags.WriteArrowStyleSignature) { + sigOutput = kind === SignatureKind.Construct ? SyntaxKind.ConstructorType : SyntaxKind.FunctionType; + } + else { + sigOutput = kind === SignatureKind.Construct ? SyntaxKind.ConstructSignature : SyntaxKind.CallSignature; + } + const sig = nodeBuilder.signatureToSignatureDeclaration(signature, sigOutput, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.WriteTypeParametersInQualifiedName); + const printer = createPrinterWithRemoveCommentsOmitTrailingSemicolon(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, sig!, /*sourceFile*/ sourceFile, getTrailingSemicolonDeferringWriter(writer)); // TODO: GH#18217 + return writer; + } + } + + function typeToString(type: Type, enclosingDeclaration?: Node, flags: TypeFormatFlags = TypeFormatFlags.AllowUniqueESSymbolType | TypeFormatFlags.UseAliasDefinedOutsideCurrentScope, writer: EmitTextWriter = createTextWriter("")): string { + const noTruncation = compilerOptions.noErrorTruncation || flags & TypeFormatFlags.NoTruncation; + const typeNode = nodeBuilder.typeToTypeNode(type, enclosingDeclaration, toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | (noTruncation ? NodeBuilderFlags.NoTruncation : 0)); + if (typeNode === undefined) return Debug.fail("should always get typenode"); + // The unresolved type gets a synthesized comment on `any` to hint to users that it's not a plain `any`. + // Otherwise, we always strip comments out. + const printer = type !== unresolvedType ? createPrinterWithRemoveComments() : createPrinterWithDefaults(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, typeNode, /*sourceFile*/ sourceFile, writer); + const result = writer.getText(); + + const maxLength = noTruncation ? noTruncationMaximumTruncationLength * 2 : defaultMaximumTruncationLength * 2; + if (maxLength && result && result.length >= maxLength) { + return result.substr(0, maxLength - "...".length) + "..."; + } + return result; + } + + function getTypeNamesForErrorDisplay(left: Type, right: Type): [string, string] { + let leftStr = symbolValueDeclarationIsContextSensitive(left.symbol) ? typeToString(left, left.symbol.valueDeclaration) : typeToString(left); + let rightStr = symbolValueDeclarationIsContextSensitive(right.symbol) ? typeToString(right, right.symbol.valueDeclaration) : typeToString(right); + if (leftStr === rightStr) { + leftStr = getTypeNameForErrorDisplay(left); + rightStr = getTypeNameForErrorDisplay(right); + } + return [leftStr, rightStr]; + } + + function getTypeNameForErrorDisplay(type: Type) { + return typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.UseFullyQualifiedType); + } + + function symbolValueDeclarationIsContextSensitive(symbol: Symbol): boolean { + return symbol && !!symbol.valueDeclaration && isExpression(symbol.valueDeclaration) && !isContextSensitive(symbol.valueDeclaration); + } + + function toNodeBuilderFlags(flags = TypeFormatFlags.None): NodeBuilderFlags { + return flags & TypeFormatFlags.NodeBuilderFlagsMask; + } + + function isClassInstanceSide(type: Type) { + return !!type.symbol && !!(type.symbol.flags & SymbolFlags.Class) && (type === getDeclaredTypeOfClassOrInterface(type.symbol) || (!!(type.flags & TypeFlags.Object) && !!(getObjectFlags(type) & ObjectFlags.IsClassInstanceClone))); + } + /** + * Same as getTypeFromTypeNode, but for use in createNodeBuilder + * Inside createNodeBuilder we shadow getTypeFromTypeNode to make sure anyone using this function will call the local version that does type mapping if appropriate + * This function is used to still be able to call the original getTypeFromTypeNode from the local scope version of getTypeFromTypeNode + */ + function getTypeFromTypeNodeWithoutContext(node: TypeNode) { + return getTypeFromTypeNode(node); + } + function createNodeBuilder() { + return { + typeToTypeNode: (type: Type, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeToTypeNodeHelper(type, context)), + typePredicateToTypePredicateNode: (typePredicate: TypePredicate, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typePredicateToTypePredicateNodeHelper(typePredicate, context)), + expressionOrTypeToTypeNode: (expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => expressionOrTypeToTypeNode(context, expr, type, addUndefined)), + serializeTypeForDeclaration: (declaration: Declaration, type: Type, symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => serializeTypeForDeclaration(context, declaration, type, symbol)), + serializeReturnTypeForSignature: (signature: Signature, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => serializeReturnTypeForSignature(context, signature)), + indexInfoToIndexSignatureDeclaration: (indexInfo: IndexInfo, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => indexInfoToIndexSignatureDeclarationHelper(indexInfo, context, /*typeNode*/ undefined)), + signatureToSignatureDeclaration: (signature: Signature, kind: SignatureDeclaration["kind"], enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => signatureToSignatureDeclarationHelper(signature, kind, context)), + symbolToEntityName: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToName(symbol, context, meaning, /*expectsIdentifier*/ false)), + symbolToExpression: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToExpression(symbol, context, meaning)), + symbolToTypeParameterDeclarations: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParametersToTypeParameterDeclarations(symbol, context)), + symbolToParameterDeclaration: (symbol: Symbol, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToParameterDeclaration(symbol, context)), + typeParameterToDeclaration: (parameter: TypeParameter, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => typeParameterToDeclaration(parameter, context)), + symbolTableToDeclarationStatements: (symbolTable: SymbolTable, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolTableToDeclarationStatements(symbolTable, context)), + symbolToNode: (symbol: Symbol, meaning: SymbolFlags, enclosingDeclaration?: Node, flags?: NodeBuilderFlags, tracker?: SymbolTracker) => withContext(enclosingDeclaration, flags, tracker, context => symbolToNode(symbol, context, meaning)), + }; + + function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes?: false): Type; + function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes: true): Type | undefined; + function getTypeFromTypeNode(context: NodeBuilderContext, node: TypeNode, noMappedTypes?: boolean): Type | undefined { + const type = getTypeFromTypeNodeWithoutContext(node); + if (!context.mapper) return type; + + const mappedType = instantiateType(type, context.mapper); + return noMappedTypes && mappedType !== type ? undefined : mappedType; + } + + /** + * Unlike the utilities `setTextRange`, this checks if the `location` we're trying to set on `range` is within the + * same file as the active context. If not, the range is not applied. This prevents us from copying ranges across files, + * which will confuse the node printer (as it assumes all node ranges are within the current file). + * Additionally, if `range` _isn't synthetic_, or isn't in the current file, it will _copy_ it to _remove_ its' position + * information. + * + * It also calls `setOriginalNode` to setup a `.original` pointer, since you basically *always* want these in the node builder. + */ + function setTextRange(context: NodeBuilderContext, range: T, location: Node | undefined): T { + if (!nodeIsSynthesized(range) || !(range.flags & NodeFlags.Synthesized) || !context.enclosingFile || context.enclosingFile !== getSourceFileOfNode(getOriginalNode(range))) { + range = factory.cloneNode(range); // if `range` is synthesized or originates in another file, copy it so it definitely has synthetic positions + } + if (range === location) return range; + if (!location) { + return range; + } + if (!context.enclosingFile || context.enclosingFile !== getSourceFileOfNode(getOriginalNode(location))) { + return setOriginalNode(range, location); // if `location` is from another file, only set/update original pointer, and not positions, since copying text across files isn't supported by the emitter + } + return setTextRangeWorker(setOriginalNode(range, location), location); + } + + /** + * Same as expressionOrTypeToTypeNodeHelper, but also checks if the expression can be syntactically typed. + */ + function expressionOrTypeToTypeNode(context: NodeBuilderContext, expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean) { + const oldFlags = context.flags; + if (expr && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) { + syntacticNodeBuilder.serializeTypeOfExpression(expr, context, addUndefined); + } + context.flags |= NodeBuilderFlags.NoSyntacticPrinter; + const result = expressionOrTypeToTypeNodeHelper(context, expr, type, addUndefined); + context.flags = oldFlags; + return result; + } + function expressionOrTypeToTypeNodeHelper(context: NodeBuilderContext, expr: Expression | JsxAttributeValue | undefined, type: Type, addUndefined?: boolean) { + if (expr) { + const typeNode = isAssertionExpression(expr) ? expr.type + : isJSDocTypeAssertion(expr) ? getJSDocTypeAssertionType(expr) + : undefined; + if (typeNode && !isConstTypeReference(typeNode)) { + const result = tryReuseExistingTypeNode(context, typeNode, type, expr.parent, addUndefined); + if (result) { + return result; + } + } + } + + if (addUndefined) { + type = getOptionalType(type); + } + + return typeToTypeNodeHelper(type, context); + } + + function tryReuseExistingTypeNode( + context: NodeBuilderContext, + typeNode: TypeNode, + type: Type, + host: Node, + addUndefined?: boolean, + ) { + const originalType = type; + if (addUndefined) { + type = getOptionalType(type); + } + const clone = tryReuseExistingNonParameterTypeNode(context, typeNode, type, host); + if (clone) { + if (addUndefined && !someType(getTypeFromTypeNode(context, typeNode), t => !!(t.flags & TypeFlags.Undefined))) { + return factory.createUnionTypeNode([clone, factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); + } + return clone; + } + if (addUndefined && originalType !== type) { + const cloneMissingUndefined = tryReuseExistingNonParameterTypeNode(context, typeNode, originalType, host); + if (cloneMissingUndefined) { + return factory.createUnionTypeNode([cloneMissingUndefined, factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); + } + } + return undefined; + } + + function tryReuseExistingNonParameterTypeNode( + context: NodeBuilderContext, + existing: TypeNode, + type: Type, + host = context.enclosingDeclaration, + annotationType = getTypeFromTypeNode(context, existing, /*noMappedTypes*/ true), + ) { + if (annotationType && typeNodeIsEquivalentToType(host, type, annotationType) && existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing, type)) { + const result = tryReuseExistingTypeNodeHelper(context, existing); + if (result) { + return result; + } + } + return undefined; + } + + function symbolToNode(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags) { + if (context.flags & NodeBuilderFlags.WriteComputedProps) { + if (symbol.valueDeclaration) { + const name = getNameOfDeclaration(symbol.valueDeclaration); + if (name && isComputedPropertyName(name)) return name; + } + const nameType = getSymbolLinks(symbol).nameType; + if (nameType && nameType.flags & (TypeFlags.EnumLiteral | TypeFlags.UniqueESSymbol)) { + context.enclosingDeclaration = nameType.symbol.valueDeclaration; + return factory.createComputedPropertyName(symbolToExpression(nameType.symbol, context, meaning)); + } + } + return symbolToExpression(symbol, context, meaning); + } + + function withContext(enclosingDeclaration: Node | undefined, flags: NodeBuilderFlags | undefined, tracker: SymbolTracker | undefined, cb: (context: NodeBuilderContext) => T): T | undefined { + const moduleResolverHost = tracker?.trackSymbol ? tracker.moduleResolverHost : + flags! & NodeBuilderFlags.DoNotIncludeSymbolChain ? createBasicNodeBuilderModuleSpecifierResolutionHost(host) : + undefined; + const context: NodeBuilderContext = { + enclosingDeclaration, + enclosingFile: enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration), + flags: flags || NodeBuilderFlags.None, + tracker: undefined!, + encounteredError: false, + reportedDiagnostic: false, + visitedTypes: undefined, + symbolDepth: undefined, + inferTypeParameters: undefined, + approximateLength: 0, + trackedSymbols: undefined, + bundled: !!compilerOptions.outFile && !!enclosingDeclaration && isExternalOrCommonJsModule(getSourceFileOfNode(enclosingDeclaration)), + truncating: false, + usedSymbolNames: undefined, + remappedSymbolNames: undefined, + remappedSymbolReferences: undefined, + reverseMappedStack: undefined, + mustCreateTypeParameterSymbolList: true, + typeParameterSymbolList: undefined, + mustCreateTypeParametersNamesLookups: true, + typeParameterNames: undefined, + typeParameterNamesByText: undefined, + typeParameterNamesByTextNextNameCount: undefined, + mapper: undefined, + }; + context.tracker = new SymbolTrackerImpl(context, tracker, moduleResolverHost); + const resultingNode = cb(context); + if (context.truncating && context.flags & NodeBuilderFlags.NoTruncation) { + context.tracker.reportTruncationError(); + } + return context.encounteredError ? undefined : resultingNode; + } + + function checkTruncationLength(context: NodeBuilderContext): boolean { + if (context.truncating) return context.truncating; + return context.truncating = context.approximateLength > ((context.flags & NodeBuilderFlags.NoTruncation) ? noTruncationMaximumTruncationLength : defaultMaximumTruncationLength); + } + + function typeToTypeNodeHelper(type: Type, context: NodeBuilderContext): TypeNode { + const savedFlags = context.flags; + const typeNode = typeToTypeNodeWorker(type, context); + context.flags = savedFlags; + return typeNode; + } + + function typeToTypeNodeWorker(type: Type, context: NodeBuilderContext): TypeNode { + if (cancellationToken && cancellationToken.throwIfCancellationRequested) { + cancellationToken.throwIfCancellationRequested(); + } + const inTypeAlias = context.flags & NodeBuilderFlags.InTypeAlias; + context.flags &= ~NodeBuilderFlags.InTypeAlias; + + if (!type) { + if (!(context.flags & NodeBuilderFlags.AllowEmptyUnionOrIntersection)) { + context.encounteredError = true; + return undefined!; // TODO: GH#18217 + } + context.approximateLength += 3; + return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + + if (!(context.flags & NodeBuilderFlags.NoTypeReduction)) { + type = getReducedType(type); + } + + if (type.flags & TypeFlags.Any) { + if (type.aliasSymbol) { + return factory.createTypeReferenceNode(symbolToEntityNameNode(type.aliasSymbol), mapToTypeNodes(type.aliasTypeArguments, context)); + } + if (type === unresolvedType) { + return addSyntheticLeadingComment(factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), SyntaxKind.MultiLineCommentTrivia, "unresolved"); + } + context.approximateLength += 3; + return factory.createKeywordTypeNode(type === intrinsicMarkerType ? SyntaxKind.IntrinsicKeyword : SyntaxKind.AnyKeyword); + } + if (type.flags & TypeFlags.Unknown) { + return factory.createKeywordTypeNode(SyntaxKind.UnknownKeyword); + } + if (type.flags & TypeFlags.String) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.StringKeyword); + } + if (type.flags & TypeFlags.Number) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.NumberKeyword); + } + if (type.flags & TypeFlags.BigInt) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.BigIntKeyword); + } + if (type.flags & TypeFlags.Boolean && !type.aliasSymbol) { + context.approximateLength += 7; + return factory.createKeywordTypeNode(SyntaxKind.BooleanKeyword); + } + if (type.flags & TypeFlags.EnumLike) { + if (type.symbol.flags & SymbolFlags.EnumMember) { + const parentSymbol = getParentOfSymbol(type.symbol)!; + const parentName = symbolToTypeNode(parentSymbol, context, SymbolFlags.Type); + if (getDeclaredTypeOfSymbol(parentSymbol) === type) { + return parentName; + } + const memberName = symbolName(type.symbol); + if (isIdentifierText(memberName, ScriptTarget.ES5)) { + return appendReferenceToType( + parentName as TypeReferenceNode | ImportTypeNode, + factory.createTypeReferenceNode(memberName, /*typeArguments*/ undefined), + ); + } + if (isImportTypeNode(parentName)) { + (parentName as any).isTypeOf = true; // mutably update, node is freshly manufactured anyhow + return factory.createIndexedAccessTypeNode(parentName, factory.createLiteralTypeNode(factory.createStringLiteral(memberName))); + } + else if (isTypeReferenceNode(parentName)) { + return factory.createIndexedAccessTypeNode(factory.createTypeQueryNode(parentName.typeName), factory.createLiteralTypeNode(factory.createStringLiteral(memberName))); + } + else { + return Debug.fail("Unhandled type node kind returned from `symbolToTypeNode`."); + } + } + return symbolToTypeNode(type.symbol, context, SymbolFlags.Type); + } + if (type.flags & TypeFlags.StringLiteral) { + context.approximateLength += (type as StringLiteralType).value.length + 2; + return factory.createLiteralTypeNode(setEmitFlags(factory.createStringLiteral((type as StringLiteralType).value, !!(context.flags & NodeBuilderFlags.UseSingleQuotesForStringLiteralType)), EmitFlags.NoAsciiEscaping)); + } + if (type.flags & TypeFlags.NumberLiteral) { + const value = (type as NumberLiteralType).value; + context.approximateLength += ("" + value).length; + return factory.createLiteralTypeNode(value < 0 ? factory.createPrefixUnaryExpression(SyntaxKind.MinusToken, factory.createNumericLiteral(-value)) : factory.createNumericLiteral(value)); + } + if (type.flags & TypeFlags.BigIntLiteral) { + context.approximateLength += (pseudoBigIntToString((type as BigIntLiteralType).value).length) + 1; + return factory.createLiteralTypeNode(factory.createBigIntLiteral((type as BigIntLiteralType).value)); + } + if (type.flags & TypeFlags.BooleanLiteral) { + context.approximateLength += (type as IntrinsicType).intrinsicName.length; + return factory.createLiteralTypeNode((type as IntrinsicType).intrinsicName === "true" ? factory.createTrue() : factory.createFalse()); + } + if (type.flags & TypeFlags.UniqueESSymbol) { + if (!(context.flags & NodeBuilderFlags.AllowUniqueESSymbolType)) { + if (isValueSymbolAccessible(type.symbol, context.enclosingDeclaration)) { + context.approximateLength += 6; + return symbolToTypeNode(type.symbol, context, SymbolFlags.Value); + } + if (context.tracker.reportInaccessibleUniqueSymbolError) { + context.tracker.reportInaccessibleUniqueSymbolError(); + } + } + context.approximateLength += 13; + return factory.createTypeOperatorNode(SyntaxKind.UniqueKeyword, factory.createKeywordTypeNode(SyntaxKind.SymbolKeyword)); + } + if (type.flags & TypeFlags.Void) { + context.approximateLength += 4; + return factory.createKeywordTypeNode(SyntaxKind.VoidKeyword); + } + if (type.flags & TypeFlags.Undefined) { + context.approximateLength += 9; + return factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword); + } + if (type.flags & TypeFlags.Null) { + context.approximateLength += 4; + return factory.createLiteralTypeNode(factory.createNull()); + } + if (type.flags & TypeFlags.Never) { + context.approximateLength += 5; + return factory.createKeywordTypeNode(SyntaxKind.NeverKeyword); + } + if (type.flags & TypeFlags.ESSymbol) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.SymbolKeyword); + } + if (type.flags & TypeFlags.NonPrimitive) { + context.approximateLength += 6; + return factory.createKeywordTypeNode(SyntaxKind.ObjectKeyword); + } + if (isThisTypeParameter(type)) { + if (context.flags & NodeBuilderFlags.InObjectTypeLiteral) { + if (!context.encounteredError && !(context.flags & NodeBuilderFlags.AllowThisInObjectLiteral)) { + context.encounteredError = true; + } + context.tracker.reportInaccessibleThisError?.(); + } + context.approximateLength += 4; + return factory.createThisTypeNode(); + } + + if (!inTypeAlias && type.aliasSymbol && (context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope || isTypeSymbolAccessible(type.aliasSymbol, context.enclosingDeclaration))) { + const typeArgumentNodes = mapToTypeNodes(type.aliasTypeArguments, context); + if (isReservedMemberName(type.aliasSymbol.escapedName) && !(type.aliasSymbol.flags & SymbolFlags.Class)) return factory.createTypeReferenceNode(factory.createIdentifier(""), typeArgumentNodes); + if (length(typeArgumentNodes) === 1 && type.aliasSymbol === globalArrayType.symbol) { + return factory.createArrayTypeNode(typeArgumentNodes![0]); + } + return symbolToTypeNode(type.aliasSymbol, context, SymbolFlags.Type, typeArgumentNodes); + } + + const objectFlags = getObjectFlags(type); + + if (objectFlags & ObjectFlags.Reference) { + Debug.assert(!!(type.flags & TypeFlags.Object)); + return (type as TypeReference).node ? visitAndTransformType(type as TypeReference, typeReferenceToTypeNode) : typeReferenceToTypeNode(type as TypeReference); + } + if (type.flags & TypeFlags.TypeParameter || objectFlags & ObjectFlags.ClassOrInterface) { + if (type.flags & TypeFlags.TypeParameter && contains(context.inferTypeParameters, type)) { + context.approximateLength += symbolName(type.symbol).length + 6; + let constraintNode: TypeNode | undefined; + const constraint = getConstraintOfTypeParameter(type as TypeParameter); + if (constraint) { + // If the infer type has a constraint that is not the same as the constraint + // we would have normally inferred based on context, we emit the constraint + // using `infer T extends ?`. We omit inferred constraints from type references + // as they may be elided. + const inferredConstraint = getInferredTypeParameterConstraint(type as TypeParameter, /*omitTypeReferences*/ true); + if (!(inferredConstraint && isTypeIdenticalTo(constraint, inferredConstraint))) { + context.approximateLength += 9; + constraintNode = constraint && typeToTypeNodeHelper(constraint, context); + } + } + return factory.createInferTypeNode(typeParameterToDeclarationWithConstraint(type as TypeParameter, context, constraintNode)); + } + if ( + context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && + type.flags & TypeFlags.TypeParameter + ) { + const name = typeParameterToName(type, context); + context.approximateLength += idText(name).length; + return factory.createTypeReferenceNode(factory.createIdentifier(idText(name)), /*typeArguments*/ undefined); + } + // Ignore constraint/default when creating a usage (as opposed to declaration) of a type parameter. + if (type.symbol) { + return symbolToTypeNode(type.symbol, context, SymbolFlags.Type); + } + const name = (type === markerSuperTypeForCheck || type === markerSubTypeForCheck) && varianceTypeParameter && varianceTypeParameter.symbol ? + (type === markerSubTypeForCheck ? "sub-" : "super-") + symbolName(varianceTypeParameter.symbol) : "?"; + return factory.createTypeReferenceNode(factory.createIdentifier(name), /*typeArguments*/ undefined); + } + if (type.flags & TypeFlags.Union && (type as UnionType).origin) { + type = (type as UnionType).origin!; + } + if (type.flags & (TypeFlags.Union | TypeFlags.Intersection)) { + const types = type.flags & TypeFlags.Union ? formatUnionTypes((type as UnionType).types) : (type as IntersectionType).types; + if (length(types) === 1) { + return typeToTypeNodeHelper(types[0], context); + } + const typeNodes = mapToTypeNodes(types, context, /*isBareList*/ true); + if (typeNodes && typeNodes.length > 0) { + return type.flags & TypeFlags.Union ? factory.createUnionTypeNode(typeNodes) : factory.createIntersectionTypeNode(typeNodes); + } + else { + if (!context.encounteredError && !(context.flags & NodeBuilderFlags.AllowEmptyUnionOrIntersection)) { + context.encounteredError = true; + } + return undefined!; // TODO: GH#18217 + } + } + if (objectFlags & (ObjectFlags.Anonymous | ObjectFlags.Mapped)) { + Debug.assert(!!(type.flags & TypeFlags.Object)); + // The type is an object literal type. + return createAnonymousTypeNode(type as ObjectType); + } + if (type.flags & TypeFlags.Index) { + const indexedType = (type as IndexType).type; + context.approximateLength += 6; + const indexTypeNode = typeToTypeNodeHelper(indexedType, context); + return factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, indexTypeNode); + } + if (type.flags & TypeFlags.TemplateLiteral) { + const texts = (type as TemplateLiteralType).texts; + const types = (type as TemplateLiteralType).types; + const templateHead = factory.createTemplateHead(texts[0]); + const templateSpans = factory.createNodeArray( + map(types, (t, i) => + factory.createTemplateLiteralTypeSpan( + typeToTypeNodeHelper(t, context), + (i < types.length - 1 ? factory.createTemplateMiddle : factory.createTemplateTail)(texts[i + 1]), + )), + ); + context.approximateLength += 2; + return factory.createTemplateLiteralType(templateHead, templateSpans); + } + if (type.flags & TypeFlags.StringMapping) { + const typeNode = typeToTypeNodeHelper((type as StringMappingType).type, context); + return symbolToTypeNode((type as StringMappingType).symbol, context, SymbolFlags.Type, [typeNode]); + } + if (type.flags & TypeFlags.IndexedAccess) { + const objectTypeNode = typeToTypeNodeHelper((type as IndexedAccessType).objectType, context); + const indexTypeNode = typeToTypeNodeHelper((type as IndexedAccessType).indexType, context); + context.approximateLength += 2; + return factory.createIndexedAccessTypeNode(objectTypeNode, indexTypeNode); + } + if (type.flags & TypeFlags.Conditional) { + return visitAndTransformType(type, type => conditionalTypeToTypeNode(type as ConditionalType)); + } + if (type.flags & TypeFlags.Substitution) { + const typeNode = typeToTypeNodeHelper((type as SubstitutionType).baseType, context); + const noInferSymbol = isNoInferType(type) && getGlobalTypeSymbol("NoInfer" as __String, /*reportErrors*/ false); + return noInferSymbol ? symbolToTypeNode(noInferSymbol, context, SymbolFlags.Type, [typeNode]) : typeNode; + } + + return Debug.fail("Should be unreachable."); + + function conditionalTypeToTypeNode(type: ConditionalType) { + const checkTypeNode = typeToTypeNodeHelper(type.checkType, context); + context.approximateLength += 15; + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && type.root.isDistributive && !(type.checkType.flags & TypeFlags.TypeParameter)) { + const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); + const name = typeParameterToName(newParam, context); + const newTypeVariable = factory.createTypeReferenceNode(name); + context.approximateLength += 37; // 15 each for two added conditionals, 7 for an added infer type + const newMapper = prependTypeMapping(type.root.checkType, newParam, type.mapper); + const saveInferTypeParameters = context.inferTypeParameters; + context.inferTypeParameters = type.root.inferTypeParameters; + const extendsTypeNode = typeToTypeNodeHelper(instantiateType(type.root.extendsType, newMapper), context); + context.inferTypeParameters = saveInferTypeParameters; + const trueTypeNode = typeToTypeNodeOrCircularityElision(instantiateType(getTypeFromTypeNode(context, type.root.node.trueType), newMapper)); + const falseTypeNode = typeToTypeNodeOrCircularityElision(instantiateType(getTypeFromTypeNode(context, type.root.node.falseType), newMapper)); + + // outermost conditional makes `T` a type parameter, allowing the inner conditionals to be distributive + // second conditional makes `T` have `T & checkType` substitution, so it is correctly usable as the checkType + // inner conditional runs the check the user provided on the check type (distributively) and returns the result + // checkType extends infer T ? T extends checkType ? T extends extendsType ? trueType : falseType : never : never; + // this is potentially simplifiable to + // checkType extends infer T ? T extends checkType & extendsType ? trueType : falseType : never; + // but that may confuse users who read the output more. + // On the other hand, + // checkType extends infer T extends checkType ? T extends extendsType ? trueType : falseType : never; + // may also work with `infer ... extends ...` in, but would produce declarations only compatible with the latest TS. + return factory.createConditionalTypeNode( + checkTypeNode, + factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable.typeName) as Identifier)), + factory.createConditionalTypeNode( + factory.createTypeReferenceNode(factory.cloneNode(name)), + typeToTypeNodeHelper(type.checkType, context), + factory.createConditionalTypeNode(newTypeVariable, extendsTypeNode, trueTypeNode, falseTypeNode), + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ), + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ); + } + const saveInferTypeParameters = context.inferTypeParameters; + context.inferTypeParameters = type.root.inferTypeParameters; + const extendsTypeNode = typeToTypeNodeHelper(type.extendsType, context); + context.inferTypeParameters = saveInferTypeParameters; + const trueTypeNode = typeToTypeNodeOrCircularityElision(getTrueTypeFromConditionalType(type)); + const falseTypeNode = typeToTypeNodeOrCircularityElision(getFalseTypeFromConditionalType(type)); + return factory.createConditionalTypeNode(checkTypeNode, extendsTypeNode, trueTypeNode, falseTypeNode); + } + + function typeToTypeNodeOrCircularityElision(type: Type) { + if (type.flags & TypeFlags.Union) { + if (context.visitedTypes?.has(getTypeId(type))) { + if (!(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier)) { + context.encounteredError = true; + context.tracker?.reportCyclicStructureError?.(); + } + return createElidedInformationPlaceholder(context); + } + return visitAndTransformType(type, type => typeToTypeNodeHelper(type, context)); + } + return typeToTypeNodeHelper(type, context); + } + + function isMappedTypeHomomorphic(type: MappedType) { + return !!getHomomorphicTypeVariable(type); + } + + function isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type: MappedType) { + return !!type.target && isMappedTypeHomomorphic(type.target as MappedType) && !isMappedTypeHomomorphic(type); + } + + function createMappedTypeNodeFromType(type: MappedType) { + Debug.assert(!!(type.flags & TypeFlags.Object)); + const readonlyToken = type.declaration.readonlyToken ? factory.createToken(type.declaration.readonlyToken.kind) as ReadonlyKeyword | PlusToken | MinusToken : undefined; + const questionToken = type.declaration.questionToken ? factory.createToken(type.declaration.questionToken.kind) as QuestionToken | PlusToken | MinusToken : undefined; + let appropriateConstraintTypeNode: TypeNode; + let newTypeVariable: TypeReferenceNode | undefined; + // If the mapped type isn't `keyof` constraint-declared, _but_ still has modifiers preserved, and its naive instantiation won't preserve modifiers because its constraint isn't `keyof` constrained, we have work to do + const needsModifierPreservingWrapper = !isMappedTypeWithKeyofConstraintDeclaration(type) + && !(getModifiersTypeFromMappedType(type).flags & TypeFlags.Unknown) + && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams + && !(getConstraintTypeFromMappedType(type).flags & TypeFlags.TypeParameter && getConstraintOfTypeParameter(getConstraintTypeFromMappedType(type))?.flags! & TypeFlags.Index); + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // We have a { [P in keyof T]: X } + // We do this to ensure we retain the toplevel keyof-ness of the type which may be lost due to keyof distribution during `getConstraintTypeFromMappedType` + if (isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type) && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { + const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); + const name = typeParameterToName(newParam, context); + newTypeVariable = factory.createTypeReferenceNode(name); + } + appropriateConstraintTypeNode = factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, newTypeVariable || typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context)); + } + else if (needsModifierPreservingWrapper) { + // So, step 1: new type variable + const newParam = createTypeParameter(createSymbol(SymbolFlags.TypeParameter, "T" as __String)); + const name = typeParameterToName(newParam, context); + newTypeVariable = factory.createTypeReferenceNode(name); + // step 2: make that new type variable itself the constraint node, making the mapped type `{[K in T_1]: Template}` + appropriateConstraintTypeNode = newTypeVariable; + } + else { + appropriateConstraintTypeNode = typeToTypeNodeHelper(getConstraintTypeFromMappedType(type), context); + } + const typeParameterNode = typeParameterToDeclarationWithConstraint(getTypeParameterFromMappedType(type), context, appropriateConstraintTypeNode); + const nameTypeNode = type.declaration.nameType ? typeToTypeNodeHelper(getNameTypeFromMappedType(type)!, context) : undefined; + const templateTypeNode = typeToTypeNodeHelper(removeMissingType(getTemplateTypeFromMappedType(type), !!(getMappedTypeModifiers(type) & MappedTypeModifiers.IncludeOptional)), context); + const mappedTypeNode = factory.createMappedTypeNode(readonlyToken, typeParameterNode, nameTypeNode, questionToken, templateTypeNode, /*members*/ undefined); + context.approximateLength += 10; + const result = setEmitFlags(mappedTypeNode, EmitFlags.SingleLine); + if (isHomomorphicMappedTypeWithNonHomomorphicInstantiation(type) && context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { + // homomorphic mapped type with a non-homomorphic naive inlining + // wrap it with a conditional like `SomeModifiersType extends infer U ? {..the mapped type...} : never` to ensure the resulting + // type stays homomorphic + const originalConstraint = instantiateType(getConstraintOfTypeParameter(getTypeFromTypeNode(context, (type.declaration.typeParameter.constraint! as TypeOperatorNode).type) as TypeParameter) || unknownType, type.mapper); + return factory.createConditionalTypeNode( + typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context), + factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable!.typeName) as Identifier, originalConstraint.flags & TypeFlags.Unknown ? undefined : typeToTypeNodeHelper(originalConstraint, context))), + result, + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ); + } + else if (needsModifierPreservingWrapper) { + // and step 3: once the mapped type is reconstructed, create a `ConstraintType extends infer T_1 extends keyof ModifiersType ? {[K in T_1]: Template} : never` + // subtly different from the `keyof` constraint case, by including the `keyof` constraint on the `infer` type parameter, it doesn't rely on the constraint type being itself + // constrained to a `keyof` type to preserve its modifier-preserving behavior. This is all basically because we preserve modifiers for a wider set of mapped types than + // just homomorphic ones. + return factory.createConditionalTypeNode( + typeToTypeNodeHelper(getConstraintTypeFromMappedType(type), context), + factory.createInferTypeNode(factory.createTypeParameterDeclaration(/*modifiers*/ undefined, factory.cloneNode(newTypeVariable!.typeName) as Identifier, factory.createTypeOperatorNode(SyntaxKind.KeyOfKeyword, typeToTypeNodeHelper(getModifiersTypeFromMappedType(type), context)))), + result, + factory.createKeywordTypeNode(SyntaxKind.NeverKeyword), + ); + } + return result; + } + + function createAnonymousTypeNode(type: ObjectType): TypeNode { + const typeId = type.id; + const symbol = type.symbol; + if (symbol) { + const isInstantiationExpressionType = !!(getObjectFlags(type) & ObjectFlags.InstantiationExpressionType); + if (isInstantiationExpressionType) { + const instantiationExpressionType = type as InstantiationExpressionType; + const existing = instantiationExpressionType.node; + if (isTypeQueryNode(existing)) { + const typeNode = tryReuseExistingNonParameterTypeNode(context, existing, type); + if (typeNode) { + return typeNode; + } + } + if (context.visitedTypes?.has(typeId)) { + return createElidedInformationPlaceholder(context); + } + return visitAndTransformType(type, createTypeNodeFromObjectType); + } + const isInstanceType = isClassInstanceSide(type) ? SymbolFlags.Type : SymbolFlags.Value; + if (isJSConstructor(symbol.valueDeclaration)) { + // Instance and static types share the same symbol; only add 'typeof' for the static side. + return symbolToTypeNode(symbol, context, isInstanceType); + } + // Always use 'typeof T' for type of class, enum, and module objects + else if ( + symbol.flags & SymbolFlags.Class + && !getBaseTypeVariableOfClass(symbol) + && !(symbol.valueDeclaration && isClassLike(symbol.valueDeclaration) && context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral && (!isClassDeclaration(symbol.valueDeclaration) || isSymbolAccessible(symbol, context.enclosingDeclaration, isInstanceType, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible)) || + symbol.flags & (SymbolFlags.Enum | SymbolFlags.ValueModule) || + shouldWriteTypeOfFunctionSymbol() + ) { + return symbolToTypeNode(symbol, context, isInstanceType); + } + else if (context.visitedTypes?.has(typeId)) { + // If type is an anonymous type literal in a type alias declaration, use type alias name + const typeAlias = getTypeAliasForTypeLiteral(type); + if (typeAlias) { + // The specified symbol flags need to be reinterpreted as type flags + return symbolToTypeNode(typeAlias, context, SymbolFlags.Type); + } + else { + return createElidedInformationPlaceholder(context); + } + } + else { + return visitAndTransformType(type, createTypeNodeFromObjectType); + } + } + else { + // Anonymous types without a symbol are never circular. + return createTypeNodeFromObjectType(type); + } + function shouldWriteTypeOfFunctionSymbol() { + const isStaticMethodSymbol = !!(symbol.flags & SymbolFlags.Method) && // typeof static method + some(symbol.declarations, declaration => isStatic(declaration)); + const isNonLocalFunctionSymbol = !!(symbol.flags & SymbolFlags.Function) && + (symbol.parent || // is exported function symbol + forEach(symbol.declarations, declaration => declaration.parent.kind === SyntaxKind.SourceFile || declaration.parent.kind === SyntaxKind.ModuleBlock)); + if (isStaticMethodSymbol || isNonLocalFunctionSymbol) { + // typeof is allowed only for static/non local functions + return (!!(context.flags & NodeBuilderFlags.UseTypeOfFunction) || (context.visitedTypes?.has(typeId))) && // it is type of the symbol uses itself recursively + (!(context.flags & NodeBuilderFlags.UseStructuralFallback) || isValueSymbolAccessible(symbol, context.enclosingDeclaration)); // And the build is going to succeed without visibility error or there is no structural fallback allowed + } + } + } + + function visitAndTransformType(type: T, transform: (type: T) => TypeNode) { + const typeId = type.id; + const isConstructorObject = getObjectFlags(type) & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & SymbolFlags.Class; + const id = getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference & T).node ? "N" + getNodeId((type as TypeReference & T).node!) : + type.flags & TypeFlags.Conditional ? "N" + getNodeId((type as ConditionalType & T).root.node) : + type.symbol ? (isConstructorObject ? "+" : "") + getSymbolId(type.symbol) : + undefined; + // Since instantiations of the same anonymous type have the same symbol, tracking symbols instead + // of types allows us to catch circular references to instantiations of the same anonymous type + if (!context.visitedTypes) { + context.visitedTypes = new Set(); + } + if (id && !context.symbolDepth) { + context.symbolDepth = new Map(); + } + + const links = context.enclosingDeclaration && getNodeLinks(context.enclosingDeclaration); + const key = `${getTypeId(type)}|${context.flags}`; + if (links) { + links.serializedTypes ||= new Map(); + } + const cachedResult = links?.serializedTypes?.get(key); + if (cachedResult) { + // TODO:: check if we instead store late painted statements associated with this? + cachedResult.trackedSymbols?.forEach( + ([symbol, enclosingDeclaration, meaning]) => + context.tracker.trackSymbol( + symbol, + enclosingDeclaration, + meaning, + ), + ); + if (cachedResult.truncating) { + context.truncating = true; + } + context.approximateLength += cachedResult.addedLength; + return deepCloneOrReuseNode(cachedResult.node); + } + + let depth: number | undefined; + if (id) { + depth = context.symbolDepth!.get(id) || 0; + if (depth > 10) { + return createElidedInformationPlaceholder(context); + } + context.symbolDepth!.set(id, depth + 1); + } + context.visitedTypes.add(typeId); + const prevTrackedSymbols = context.trackedSymbols; + context.trackedSymbols = undefined; + const startLength = context.approximateLength; + const result = transform(type); + const addedLength = context.approximateLength - startLength; + if (!context.reportedDiagnostic && !context.encounteredError) { + links?.serializedTypes?.set(key, { + node: result, + truncating: context.truncating, + addedLength, + trackedSymbols: context.trackedSymbols, + }); + } + context.visitedTypes.delete(typeId); + if (id) { + context.symbolDepth!.set(id, depth!); + } + context.trackedSymbols = prevTrackedSymbols; + return result; + + function deepCloneOrReuseNode(node: T): T { + if (!nodeIsSynthesized(node) && getParseTreeNode(node) === node) { + return node; + } + return setTextRange(context, factory.cloneNode(visitEachChildWorker(node, deepCloneOrReuseNode, /*context*/ undefined, deepCloneOrReuseNodes, deepCloneOrReuseNode)), node); + } + + function deepCloneOrReuseNodes( + nodes: NodeArray | undefined, + visitor: Visitor, + test?: (node: Node) => boolean, + start?: number, + count?: number, + ): NodeArray | undefined { + if (nodes && nodes.length === 0) { + // Ensure we explicitly make a copy of an empty array; visitNodes will not do this unless the array has elements, + // which can lead to us reusing the same empty NodeArray more than once within the same AST during type noding. + return setTextRangeWorker(factory.createNodeArray(/*elements*/ undefined, nodes.hasTrailingComma), nodes); + } + return visitNodes(nodes, visitor, test, start, count); + } + } + + function createTypeNodeFromObjectType(type: ObjectType): TypeNode { + if (isGenericMappedType(type) || (type as MappedType).containsError) { + return createMappedTypeNodeFromType(type as MappedType); + } + + const resolved = resolveStructuredTypeMembers(type); + if (!resolved.properties.length && !resolved.indexInfos.length) { + if (!resolved.callSignatures.length && !resolved.constructSignatures.length) { + context.approximateLength += 2; + return setEmitFlags(factory.createTypeLiteralNode(/*members*/ undefined), EmitFlags.SingleLine); + } + + if (resolved.callSignatures.length === 1 && !resolved.constructSignatures.length) { + const signature = resolved.callSignatures[0]; + const signatureNode = signatureToSignatureDeclarationHelper(signature, SyntaxKind.FunctionType, context) as FunctionTypeNode; + return signatureNode; + } + + if (resolved.constructSignatures.length === 1 && !resolved.callSignatures.length) { + const signature = resolved.constructSignatures[0]; + const signatureNode = signatureToSignatureDeclarationHelper(signature, SyntaxKind.ConstructorType, context) as ConstructorTypeNode; + return signatureNode; + } + } + + const abstractSignatures = filter(resolved.constructSignatures, signature => !!(signature.flags & SignatureFlags.Abstract)); + if (some(abstractSignatures)) { + const types = map(abstractSignatures, s => getOrCreateTypeFromSignature(s)); + // count the number of type elements excluding abstract constructors + const typeElementCount = resolved.callSignatures.length + + (resolved.constructSignatures.length - abstractSignatures.length) + + resolved.indexInfos.length + + // exclude `prototype` when writing a class expression as a type literal, as per + // the logic in `createTypeNodesFromResolvedType`. + (context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral ? + countWhere(resolved.properties, p => !(p.flags & SymbolFlags.Prototype)) : + length(resolved.properties)); + // don't include an empty object literal if there were no other static-side + // properties to write, i.e. `abstract class C { }` becomes `abstract new () => {}` + // and not `(abstract new () => {}) & {}` + if (typeElementCount) { + // create a copy of the object type without any abstract construct signatures. + types.push(getResolvedTypeWithoutAbstractConstructSignatures(resolved)); + } + return typeToTypeNodeHelper(getIntersectionType(types), context); + } + + const savedFlags = context.flags; + context.flags |= NodeBuilderFlags.InObjectTypeLiteral; + const members = createTypeNodesFromResolvedType(resolved); + context.flags = savedFlags; + const typeLiteralNode = factory.createTypeLiteralNode(members); + context.approximateLength += 2; + setEmitFlags(typeLiteralNode, (context.flags & NodeBuilderFlags.MultilineObjectLiterals) ? 0 : EmitFlags.SingleLine); + return typeLiteralNode; + } + + function typeReferenceToTypeNode(type: TypeReference) { + let typeArguments: readonly Type[] = getTypeArguments(type); + if (type.target === globalArrayType || type.target === globalReadonlyArrayType) { + if (context.flags & NodeBuilderFlags.WriteArrayAsGenericType) { + const typeArgumentNode = typeToTypeNodeHelper(typeArguments[0], context); + return factory.createTypeReferenceNode(type.target === globalArrayType ? "Array" : "ReadonlyArray", [typeArgumentNode]); + } + const elementType = typeToTypeNodeHelper(typeArguments[0], context); + const arrayType = factory.createArrayTypeNode(elementType); + return type.target === globalArrayType ? arrayType : factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, arrayType); + } + else if (type.target.objectFlags & ObjectFlags.Tuple) { + typeArguments = sameMap(typeArguments, (t, i) => removeMissingType(t, !!((type.target as TupleType).elementFlags[i] & ElementFlags.Optional))); + if (typeArguments.length > 0) { + const arity = getTypeReferenceArity(type); + const tupleConstituentNodes = mapToTypeNodes(typeArguments.slice(0, arity), context); + if (tupleConstituentNodes) { + const { labeledElementDeclarations } = type.target as TupleType; + for (let i = 0; i < tupleConstituentNodes.length; i++) { + const flags = (type.target as TupleType).elementFlags[i]; + const labeledElementDeclaration = labeledElementDeclarations?.[i]; + + if (labeledElementDeclaration) { + tupleConstituentNodes[i] = factory.createNamedTupleMember( + flags & ElementFlags.Variable ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined, + factory.createIdentifier(unescapeLeadingUnderscores(getTupleElementLabel(labeledElementDeclaration))), + flags & ElementFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + flags & ElementFlags.Rest ? factory.createArrayTypeNode(tupleConstituentNodes[i]) : + tupleConstituentNodes[i], + ); + } + else { + tupleConstituentNodes[i] = flags & ElementFlags.Variable ? factory.createRestTypeNode(flags & ElementFlags.Rest ? factory.createArrayTypeNode(tupleConstituentNodes[i]) : tupleConstituentNodes[i]) : + flags & ElementFlags.Optional ? factory.createOptionalTypeNode(tupleConstituentNodes[i]) : + tupleConstituentNodes[i]; + } + } + const tupleTypeNode = setEmitFlags(factory.createTupleTypeNode(tupleConstituentNodes), EmitFlags.SingleLine); + return (type.target as TupleType).readonly ? factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, tupleTypeNode) : tupleTypeNode; + } + } + if (context.encounteredError || (context.flags & NodeBuilderFlags.AllowEmptyTuple)) { + const tupleTypeNode = setEmitFlags(factory.createTupleTypeNode([]), EmitFlags.SingleLine); + return (type.target as TupleType).readonly ? factory.createTypeOperatorNode(SyntaxKind.ReadonlyKeyword, tupleTypeNode) : tupleTypeNode; + } + context.encounteredError = true; + return undefined!; // TODO: GH#18217 + } + else if ( + context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral && + type.symbol.valueDeclaration && + isClassLike(type.symbol.valueDeclaration) && + !isValueSymbolAccessible(type.symbol, context.enclosingDeclaration) + ) { + return createAnonymousTypeNode(type); + } + else { + const outerTypeParameters = type.target.outerTypeParameters; + let i = 0; + let resultType: TypeReferenceNode | ImportTypeNode | undefined; + if (outerTypeParameters) { + const length = outerTypeParameters.length; + while (i < length) { + // Find group of type arguments for type parameters with the same declaring container. + const start = i; + const parent = getParentSymbolOfTypeParameter(outerTypeParameters[i])!; + do { + i++; + } + while (i < length && getParentSymbolOfTypeParameter(outerTypeParameters[i]) === parent); + // When type parameters are their own type arguments for the whole group (i.e. we have + // the default outer type arguments), we don't show the group. + if (!rangeEquals(outerTypeParameters, typeArguments, start, i)) { + const typeArgumentSlice = mapToTypeNodes(typeArguments.slice(start, i), context); + const flags = context.flags; + context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences; + const ref = symbolToTypeNode(parent, context, SymbolFlags.Type, typeArgumentSlice) as TypeReferenceNode | ImportTypeNode; + context.flags = flags; + resultType = !resultType ? ref : appendReferenceToType(resultType, ref as TypeReferenceNode); + } + } + } + let typeArgumentNodes: readonly TypeNode[] | undefined; + if (typeArguments.length > 0) { + const typeParameterCount = (type.target.typeParameters || emptyArray).length; + typeArgumentNodes = mapToTypeNodes(typeArguments.slice(i, typeParameterCount), context); + } + const flags = context.flags; + context.flags |= NodeBuilderFlags.ForbidIndexedAccessSymbolReferences; + const finalRef = symbolToTypeNode(type.symbol, context, SymbolFlags.Type, typeArgumentNodes); + context.flags = flags; + return !resultType ? finalRef : appendReferenceToType(resultType, finalRef as TypeReferenceNode); + } + } + + function appendReferenceToType(root: TypeReferenceNode | ImportTypeNode, ref: TypeReferenceNode): TypeReferenceNode | ImportTypeNode { + if (isImportTypeNode(root)) { + // first shift type arguments + let typeArguments = root.typeArguments; + let qualifier = root.qualifier; + if (qualifier) { + if (isIdentifier(qualifier)) { + if (typeArguments !== getIdentifierTypeArguments(qualifier)) { + qualifier = setIdentifierTypeArguments(factory.cloneNode(qualifier), typeArguments); + } + } + else { + if (typeArguments !== getIdentifierTypeArguments(qualifier.right)) { + qualifier = factory.updateQualifiedName(qualifier, qualifier.left, setIdentifierTypeArguments(factory.cloneNode(qualifier.right), typeArguments)); + } + } + } + typeArguments = ref.typeArguments; + // then move qualifiers + const ids = getAccessStack(ref); + for (const id of ids) { + qualifier = qualifier ? factory.createQualifiedName(qualifier, id) : id; + } + return factory.updateImportTypeNode( + root, + root.argument, + root.attributes, + qualifier, + typeArguments, + root.isTypeOf, + ); + } + else { + // first shift type arguments + let typeArguments = root.typeArguments; + let typeName = root.typeName; + if (isIdentifier(typeName)) { + if (typeArguments !== getIdentifierTypeArguments(typeName)) { + typeName = setIdentifierTypeArguments(factory.cloneNode(typeName), typeArguments); + } + } + else { + if (typeArguments !== getIdentifierTypeArguments(typeName.right)) { + typeName = factory.updateQualifiedName(typeName, typeName.left, setIdentifierTypeArguments(factory.cloneNode(typeName.right), typeArguments)); + } + } + typeArguments = ref.typeArguments; + // then move qualifiers + const ids = getAccessStack(ref); + for (const id of ids) { + typeName = factory.createQualifiedName(typeName, id); + } + return factory.updateTypeReferenceNode( + root, + typeName, + typeArguments, + ); + } + } + + function getAccessStack(ref: TypeReferenceNode): Identifier[] { + let state = ref.typeName; + const ids = []; + while (!isIdentifier(state)) { + ids.unshift(state.right); + state = state.left; + } + ids.unshift(state); + return ids; + } + + function createTypeNodesFromResolvedType(resolvedType: ResolvedType): TypeElement[] | undefined { + if (checkTruncationLength(context)) { + return [factory.createPropertySignature(/*modifiers*/ undefined, "...", /*questionToken*/ undefined, /*type*/ undefined)]; + } + const typeElements: TypeElement[] = []; + for (const signature of resolvedType.callSignatures) { + typeElements.push(signatureToSignatureDeclarationHelper(signature, SyntaxKind.CallSignature, context) as CallSignatureDeclaration); + } + for (const signature of resolvedType.constructSignatures) { + if (signature.flags & SignatureFlags.Abstract) continue; + typeElements.push(signatureToSignatureDeclarationHelper(signature, SyntaxKind.ConstructSignature, context) as ConstructSignatureDeclaration); + } + for (const info of resolvedType.indexInfos) { + typeElements.push(indexInfoToIndexSignatureDeclarationHelper(info, context, resolvedType.objectFlags & ObjectFlags.ReverseMapped ? createElidedInformationPlaceholder(context) : undefined)); + } + + const properties = resolvedType.properties; + if (!properties) { + return typeElements; + } + + let i = 0; + for (const propertySymbol of properties) { + i++; + if (context.flags & NodeBuilderFlags.WriteClassExpressionAsTypeLiteral) { + if (propertySymbol.flags & SymbolFlags.Prototype) { + continue; + } + if (getDeclarationModifierFlagsFromSymbol(propertySymbol) & (ModifierFlags.Private | ModifierFlags.Protected) && context.tracker.reportPrivateInBaseOfClassExpression) { + context.tracker.reportPrivateInBaseOfClassExpression(unescapeLeadingUnderscores(propertySymbol.escapedName)); + } + } + if (checkTruncationLength(context) && (i + 2 < properties.length - 1)) { + typeElements.push(factory.createPropertySignature(/*modifiers*/ undefined, `... ${properties.length - i} more ...`, /*questionToken*/ undefined, /*type*/ undefined)); + addPropertyToElementList(properties[properties.length - 1], context, typeElements); + break; + } + addPropertyToElementList(propertySymbol, context, typeElements); + } + return typeElements.length ? typeElements : undefined; + } + } + + function createElidedInformationPlaceholder(context: NodeBuilderContext) { + context.approximateLength += 3; + if (!(context.flags & NodeBuilderFlags.NoTruncation)) { + return factory.createTypeReferenceNode(factory.createIdentifier("..."), /*typeArguments*/ undefined); + } + return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + + function shouldUsePlaceholderForProperty(propertySymbol: Symbol, context: NodeBuilderContext) { + // Use placeholders for reverse mapped types we've either already descended into, or which + // are nested reverse mappings within a mapping over a non-anonymous type. The later is a restriction mostly just to + // reduce the blowup in printback size from doing, eg, a deep reverse mapping over `Window`. + // Since anonymous types usually come from expressions, this allows us to preserve the output + // for deep mappings which likely come from expressions, while truncating those parts which + // come from mappings over library functions. + return !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped) + && ( + contains(context.reverseMappedStack, propertySymbol as ReverseMappedSymbol) + || ( + context.reverseMappedStack?.[0] + && !(getObjectFlags(last(context.reverseMappedStack).links.propertyType) & ObjectFlags.Anonymous) + ) + ); + } + + function addPropertyToElementList(propertySymbol: Symbol, context: NodeBuilderContext, typeElements: TypeElement[]) { + const propertyIsReverseMapped = !!(getCheckFlags(propertySymbol) & CheckFlags.ReverseMapped); + const propertyType = shouldUsePlaceholderForProperty(propertySymbol, context) ? + anyType : getNonMissingTypeOfSymbol(propertySymbol); + const saveEnclosingDeclaration = context.enclosingDeclaration; + context.enclosingDeclaration = undefined; + if (context.tracker.canTrackSymbol && isLateBoundName(propertySymbol.escapedName)) { + if (propertySymbol.declarations) { + const decl = first(propertySymbol.declarations); + if (hasLateBindableName(decl)) { + if (isBinaryExpression(decl)) { + const name = getNameOfDeclaration(decl); + if (name && isElementAccessExpression(name) && isPropertyAccessEntityNameExpression(name.argumentExpression)) { + trackComputedName(name.argumentExpression, saveEnclosingDeclaration, context); + } + } + else { + trackComputedName(decl.name.expression, saveEnclosingDeclaration, context); + } + } + } + else { + context.tracker.reportNonSerializableProperty(symbolToString(propertySymbol)); + } + } + context.enclosingDeclaration = propertySymbol.valueDeclaration || propertySymbol.declarations?.[0] || saveEnclosingDeclaration; + const propertyName = getPropertyNameNodeForSymbol(propertySymbol, context); + context.enclosingDeclaration = saveEnclosingDeclaration; + context.approximateLength += symbolName(propertySymbol).length + 1; + + if (propertySymbol.flags & SymbolFlags.Accessor) { + const writeType = getWriteTypeOfSymbol(propertySymbol); + if (propertyType !== writeType && !isErrorType(propertyType) && !isErrorType(writeType)) { + const getterDeclaration = getDeclarationOfKind(propertySymbol, SyntaxKind.GetAccessor)!; + const getterSignature = getSignatureFromDeclaration(getterDeclaration); + typeElements.push( + setCommentRange( + context, + signatureToSignatureDeclarationHelper(getterSignature, SyntaxKind.GetAccessor, context, { name: propertyName }) as GetAccessorDeclaration, + getterDeclaration, + ), + ); + const setterDeclaration = getDeclarationOfKind(propertySymbol, SyntaxKind.SetAccessor)!; + const setterSignature = getSignatureFromDeclaration(setterDeclaration); + typeElements.push( + setCommentRange( + context, + signatureToSignatureDeclarationHelper(setterSignature, SyntaxKind.SetAccessor, context, { name: propertyName }) as SetAccessorDeclaration, + setterDeclaration, + ), + ); + return; + } + } + + const optionalToken = propertySymbol.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined; + if (propertySymbol.flags & (SymbolFlags.Function | SymbolFlags.Method) && !getPropertiesOfObjectType(propertyType).length && !isReadonlySymbol(propertySymbol)) { + const signatures = getSignaturesOfType(filterType(propertyType, t => !(t.flags & TypeFlags.Undefined)), SignatureKind.Call); + for (const signature of signatures) { + const methodDeclaration = signatureToSignatureDeclarationHelper(signature, SyntaxKind.MethodSignature, context, { name: propertyName, questionToken: optionalToken }) as MethodSignature; + typeElements.push(preserveCommentsOn(methodDeclaration)); + } + if (signatures.length || !optionalToken) { + return; + } + } + let propertyTypeNode: TypeNode; + if (shouldUsePlaceholderForProperty(propertySymbol, context)) { + propertyTypeNode = createElidedInformationPlaceholder(context); + } + else { + if (propertyIsReverseMapped) { + context.reverseMappedStack ||= []; + context.reverseMappedStack.push(propertySymbol as ReverseMappedSymbol); + } + propertyTypeNode = propertyType ? serializeTypeForDeclaration(context, /*declaration*/ undefined, propertyType, propertySymbol) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + if (propertyIsReverseMapped) { + context.reverseMappedStack!.pop(); + } + } + + const modifiers = isReadonlySymbol(propertySymbol) ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined; + if (modifiers) { + context.approximateLength += 9; + } + const propertySignature = factory.createPropertySignature( + modifiers, + propertyName, + optionalToken, + propertyTypeNode, + ); + + typeElements.push(preserveCommentsOn(propertySignature)); + + function preserveCommentsOn(node: T) { + const jsdocPropertyTag = propertySymbol.declarations?.find((d): d is JSDocPropertyTag => d.kind === SyntaxKind.JSDocPropertyTag); + if (jsdocPropertyTag) { + const commentText = getTextOfJSDocComment(jsdocPropertyTag.comment); + if (commentText) { + setSyntheticLeadingComments(node, [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }]); + } + } + else if (propertySymbol.valueDeclaration) { + // Copy comments to node for declaration emit + setCommentRange(context, node, propertySymbol.valueDeclaration); + } + return node; + } + } + + function setCommentRange(context: NodeBuilderContext, node: T, range: Node): T { + if (context.enclosingFile && context.enclosingFile === getSourceFileOfNode(range)) { + // Copy comments to node for declaration emit + return setCommentRangeWorker(node, range); + } + return node; + } + + function mapToTypeNodes(types: readonly Type[] | undefined, context: NodeBuilderContext, isBareList?: boolean): TypeNode[] | undefined { + if (some(types)) { + if (checkTruncationLength(context)) { + if (!isBareList) { + return [factory.createTypeReferenceNode("...", /*typeArguments*/ undefined)]; + } + else if (types.length > 2) { + return [ + typeToTypeNodeHelper(types[0], context), + factory.createTypeReferenceNode(`... ${types.length - 2} more ...`, /*typeArguments*/ undefined), + typeToTypeNodeHelper(types[types.length - 1], context), + ]; + } + } + const mayHaveNameCollisions = !(context.flags & NodeBuilderFlags.UseFullyQualifiedType); + /** Map from type reference identifier text to [type, index in `result` where the type node is] */ + const seenNames = mayHaveNameCollisions ? createMultiMap<__String, [Type, number]>() : undefined; + const result: TypeNode[] = []; + let i = 0; + for (const type of types) { + i++; + if (checkTruncationLength(context) && (i + 2 < types.length - 1)) { + result.push(factory.createTypeReferenceNode(`... ${types.length - i} more ...`, /*typeArguments*/ undefined)); + const typeNode = typeToTypeNodeHelper(types[types.length - 1], context); + if (typeNode) { + result.push(typeNode); + } + break; + } + context.approximateLength += 2; // Account for whitespace + separator + const typeNode = typeToTypeNodeHelper(type, context); + if (typeNode) { + result.push(typeNode); + if (seenNames && isIdentifierTypeReference(typeNode)) { + seenNames.add(typeNode.typeName.escapedText, [type, result.length - 1]); + } + } + } + + if (seenNames) { + // To avoid printing types like `[Foo, Foo]` or `Bar & Bar` where + // occurrences of the same name actually come from different + // namespaces, go through the single-identifier type reference nodes + // we just generated, and see if any names were generated more than + // once while referring to different types. If so, regenerate the + // type node for each entry by that name with the + // `UseFullyQualifiedType` flag enabled. + const saveContextFlags = context.flags; + context.flags |= NodeBuilderFlags.UseFullyQualifiedType; + seenNames.forEach(types => { + if (!arrayIsHomogeneous(types, ([a], [b]) => typesAreSameReference(a, b))) { + for (const [type, resultIndex] of types) { + result[resultIndex] = typeToTypeNodeHelper(type, context); + } + } + }); + context.flags = saveContextFlags; + } + + return result; + } + } + + function typesAreSameReference(a: Type, b: Type): boolean { + return a === b + || !!a.symbol && a.symbol === b.symbol + || !!a.aliasSymbol && a.aliasSymbol === b.aliasSymbol; + } + + function indexInfoToIndexSignatureDeclarationHelper(indexInfo: IndexInfo, context: NodeBuilderContext, typeNode: TypeNode | undefined): IndexSignatureDeclaration { + const name = getNameFromIndexInfo(indexInfo) || "x"; + const indexerTypeNode = typeToTypeNodeHelper(indexInfo.keyType, context); + + const indexingParameter = factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + name, + /*questionToken*/ undefined, + indexerTypeNode, + /*initializer*/ undefined, + ); + if (!typeNode) { + typeNode = typeToTypeNodeHelper(indexInfo.type || anyType, context); + } + if (!indexInfo.type && !(context.flags & NodeBuilderFlags.AllowEmptyIndexInfoType)) { + context.encounteredError = true; + } + context.approximateLength += name.length + 4; + return factory.createIndexSignature( + indexInfo.isReadonly ? [factory.createToken(SyntaxKind.ReadonlyKeyword)] : undefined, + [indexingParameter], + typeNode, + ); + } + + interface SignatureToSignatureDeclarationOptions { + modifiers?: readonly Modifier[]; + name?: PropertyName; + questionToken?: QuestionToken; + } + + function signatureToSignatureDeclarationHelper(signature: Signature, kind: SignatureDeclaration["kind"], context: NodeBuilderContext, options?: SignatureToSignatureDeclarationOptions): SignatureDeclaration { + let typeParameters: TypeParameterDeclaration[] | undefined; + let typeArguments: TypeNode[] | undefined; + + const expandedParams = getExpandedParameters(signature, /*skipUnionExpanding*/ true)[0]; + const cleanup = enterNewScope(context, signature.declaration, expandedParams, signature.typeParameters, signature.parameters, signature.mapper); + context.approximateLength += 3; // Usually a signature contributes a few more characters than this, but 3 is the minimum + + if (context.flags & NodeBuilderFlags.WriteTypeArgumentsOfSignature && signature.target && signature.mapper && signature.target.typeParameters) { + typeArguments = signature.target.typeParameters.map(parameter => typeToTypeNodeHelper(instantiateType(parameter, signature.mapper), context)); + } + else { + typeParameters = signature.typeParameters && signature.typeParameters.map(parameter => typeParameterToDeclaration(parameter, context)); + } + + const flags = context.flags; + context.flags &= ~NodeBuilderFlags.SuppressAnyReturnType; // SuppressAnyReturnType should only apply to the signature `return` position + // If the expanded parameter list had a variadic in a non-trailing position, don't expand it + const parameters = (some(expandedParams, p => p !== expandedParams[expandedParams.length - 1] && !!(getCheckFlags(p) & CheckFlags.RestParameter)) ? signature.parameters : expandedParams).map(parameter => symbolToParameterDeclaration(parameter, context, kind === SyntaxKind.Constructor)); + const thisParameter = context.flags & NodeBuilderFlags.OmitThisParameter ? undefined : tryGetThisParameterDeclaration(signature, context); + if (thisParameter) { + parameters.unshift(thisParameter); + } + context.flags = flags; + + const returnTypeNode = serializeReturnTypeForSignature(context, signature); + + let modifiers = options?.modifiers; + if ((kind === SyntaxKind.ConstructorType) && signature.flags & SignatureFlags.Abstract) { + const flags = modifiersToFlags(modifiers); + modifiers = factory.createModifiersFromModifierFlags(flags | ModifierFlags.Abstract); + } + + const node = kind === SyntaxKind.CallSignature ? factory.createCallSignature(typeParameters, parameters, returnTypeNode) : + kind === SyntaxKind.ConstructSignature ? factory.createConstructSignature(typeParameters, parameters, returnTypeNode) : + kind === SyntaxKind.MethodSignature ? factory.createMethodSignature(modifiers, options?.name ?? factory.createIdentifier(""), options?.questionToken, typeParameters, parameters, returnTypeNode) : + kind === SyntaxKind.MethodDeclaration ? factory.createMethodDeclaration(modifiers, /*asteriskToken*/ undefined, options?.name ?? factory.createIdentifier(""), /*questionToken*/ undefined, typeParameters, parameters, returnTypeNode, /*body*/ undefined) : + kind === SyntaxKind.Constructor ? factory.createConstructorDeclaration(modifiers, parameters, /*body*/ undefined) : + kind === SyntaxKind.GetAccessor ? factory.createGetAccessorDeclaration(modifiers, options?.name ?? factory.createIdentifier(""), parameters, returnTypeNode, /*body*/ undefined) : + kind === SyntaxKind.SetAccessor ? factory.createSetAccessorDeclaration(modifiers, options?.name ?? factory.createIdentifier(""), parameters, /*body*/ undefined) : + kind === SyntaxKind.IndexSignature ? factory.createIndexSignature(modifiers, parameters, returnTypeNode) : + kind === SyntaxKind.JSDocFunctionType ? factory.createJSDocFunctionType(parameters, returnTypeNode) : + kind === SyntaxKind.FunctionType ? factory.createFunctionTypeNode(typeParameters, parameters, returnTypeNode ?? factory.createTypeReferenceNode(factory.createIdentifier(""))) : + kind === SyntaxKind.ConstructorType ? factory.createConstructorTypeNode(modifiers, typeParameters, parameters, returnTypeNode ?? factory.createTypeReferenceNode(factory.createIdentifier(""))) : + kind === SyntaxKind.FunctionDeclaration ? factory.createFunctionDeclaration(modifiers, /*asteriskToken*/ undefined, options?.name ? cast(options.name, isIdentifier) : factory.createIdentifier(""), typeParameters, parameters, returnTypeNode, /*body*/ undefined) : + kind === SyntaxKind.FunctionExpression ? factory.createFunctionExpression(modifiers, /*asteriskToken*/ undefined, options?.name ? cast(options.name, isIdentifier) : factory.createIdentifier(""), typeParameters, parameters, returnTypeNode, factory.createBlock([])) : + kind === SyntaxKind.ArrowFunction ? factory.createArrowFunction(modifiers, typeParameters, parameters, returnTypeNode, /*equalsGreaterThanToken*/ undefined, factory.createBlock([])) : + Debug.assertNever(kind); + + if (typeArguments) { + node.typeArguments = factory.createNodeArray(typeArguments); + } + if (signature.declaration?.kind === SyntaxKind.JSDocSignature && signature.declaration.parent.kind === SyntaxKind.JSDocOverloadTag) { + const comment = getTextOfNode(signature.declaration.parent.parent, /*includeTrivia*/ true).slice(2, -2).split(/\r\n|\n|\r/).map(line => line.replace(/^\s+/, " ")).join("\n"); + addSyntheticLeadingComment(node, SyntaxKind.MultiLineCommentTrivia, comment, /*hasTrailingNewLine*/ true); + } + + cleanup?.(); + return node; + } + + type IntroducesNewScopeNode = SignatureDeclaration | JSDocSignature | MappedTypeNode; + + function isNewScopeNode(node: Node): node is IntroducesNewScopeNode { + return isFunctionLike(node) + || isJSDocSignature(node) + || isMappedTypeNode(node); + } + + function getTypeParametersInScope(node: IntroducesNewScopeNode | ConditionalTypeNode) { + return isFunctionLike(node) || isJSDocSignature(node) ? getSignatureFromDeclaration(node).typeParameters : + isConditionalTypeNode(node) ? getInferTypeParameters(node) : + [getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node.typeParameter))]; + } + + function getParametersInScope(node: IntroducesNewScopeNode | ConditionalTypeNode) { + return isFunctionLike(node) || isJSDocSignature(node) ? getSignatureFromDeclaration(node).parameters : undefined; + } + + function enterNewScope( + context: NodeBuilderContext, + declaration: IntroducesNewScopeNode | ConditionalTypeNode | undefined, + expandedParams: readonly Symbol[] | undefined, + typeParameters: readonly TypeParameter[] | undefined, + originalParameters?: readonly Symbol[] | undefined, + mapper?: TypeMapper, + ) { + const cleanupContext = cloneNodeBuilderContext(context); + // For regular function/method declarations, the enclosing declaration will already be signature.declaration, + // so this is a no-op, but for arrow functions and function expressions, the enclosing declaration will be + // the declaration that the arrow function / function expression is assigned to. + // + // If the parameters or return type include "typeof globalThis.paramName", using the wrong scope will lead + // us to believe that we can emit "typeof paramName" instead, even though that would refer to the parameter, + // not the global. Make sure we are in the right scope by changing the enclosingDeclaration to the function. + // + // We can't use the declaration directly; it may be in another file and so we may lose access to symbols + // accessible to the current enclosing declaration, or gain access to symbols not accessible to the current + // enclosing declaration. To keep this chain accurate, insert a fake scope into the chain which makes the + // function's parameters visible. + let cleanupParams: (() => void) | undefined; + let cleanupTypeParams: (() => void) | undefined; + const oldEnclosingDecl = context.enclosingDeclaration; + const oldMapper = context.mapper; + if (mapper) { + context.mapper = mapper; + } + if (context.enclosingDeclaration && declaration) { + // As a performance optimization, reuse the same fake scope within this chain. + // This is especially needed when we are working on an excessively deep type; + // if we don't do this, then we spend all of our time adding more and more + // scopes that need to be searched in isSymbolAccessible later. Since all we + // really want to do is to mark certain names as unavailable, we can just keep + // all of the names we're introducing in one large table and push/pop from it as + // needed; isSymbolAccessible will walk upward and find the closest "fake" scope, + // which will conveniently report on any and all faked scopes in the chain. + // + // It'd likely be better to store this somewhere else for isSymbolAccessible, but + // since that API _only_ uses the enclosing declaration (and its parents), this is + // seems like the best way to inject names into that search process. + // + // Note that we only check the most immediate enclosingDeclaration; the only place we + // could potentially add another fake scope into the chain is right here, so we don't + // traverse all ancestors. + cleanupParams = !some(expandedParams) ? undefined : pushFakeScope( + "params", + add => { + if (!expandedParams) return; + for (let pIndex = 0; pIndex < expandedParams.length; pIndex++) { + const param = expandedParams[pIndex]; + const originalParam = originalParameters?.[pIndex]; + if (originalParameters && originalParam !== param) { + // Can't reference parameters that come from an expansion + add(param.escapedName, unknownSymbol); + // Can't reference the original expanded parameter either + if (originalParam) { + add(originalParam.escapedName, unknownSymbol); + } + } + else if ( + !forEach(param.declarations, d => { + if (isParameter(d) && isBindingPattern(d.name)) { + bindPattern(d.name); + return true; + } + return undefined; + function bindPattern(p: BindingPattern): void { + forEach(p.elements, e => { + switch (e.kind) { + case SyntaxKind.OmittedExpression: + return; + case SyntaxKind.BindingElement: + return bindElement(e); + default: + return Debug.assertNever(e); + } + }); + } + function bindElement(e: BindingElement): void { + if (isBindingPattern(e.name)) { + return bindPattern(e.name); + } + const symbol = getSymbolOfDeclaration(e); + add(symbol.escapedName, symbol); + } + }) + ) { + add(param.escapedName, param); + } + } + }, + ); + + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && some(typeParameters)) { + cleanupTypeParams = pushFakeScope( + "typeParams", + add => { + for (const typeParam of typeParameters ?? emptyArray) { + const typeParamName = typeParameterToName(typeParam, context).escapedText; + add(typeParamName, typeParam.symbol); + } + }, + ); + } + + function pushFakeScope(kind: "params" | "typeParams", addAll: (addSymbol: (name: __String, symbol: Symbol) => void) => void) { + // We only ever need to look two declarations upward. + Debug.assert(context.enclosingDeclaration); + let existingFakeScope: Node | undefined; + if (getNodeLinks(context.enclosingDeclaration).fakeScopeForSignatureDeclaration === kind) { + existingFakeScope = context.enclosingDeclaration; + } + else if (context.enclosingDeclaration.parent && getNodeLinks(context.enclosingDeclaration.parent).fakeScopeForSignatureDeclaration === kind) { + existingFakeScope = context.enclosingDeclaration.parent; + } + Debug.assertOptionalNode(existingFakeScope, isBlock); + + const locals = existingFakeScope?.locals ?? createSymbolTable(); + let newLocals: __String[] | undefined; + let oldLocals: { name: __String; oldSymbol: Symbol; }[] | undefined; + addAll((name, symbol) => { + // Add cleanup information only if we don't own the fake scope + if (existingFakeScope) { + const oldSymbol = locals.get(name); + if (!oldSymbol) { + newLocals = append(newLocals, name); + } + else { + oldLocals = append(oldLocals, { name, oldSymbol }); + } + } + locals.set(name, symbol); + }); + + if (!existingFakeScope) { + // Use a Block for this; the type of the node doesn't matter so long as it + // has locals, and this is cheaper/easier than using a function-ish Node. + const fakeScope = factory.createBlock(emptyArray); + getNodeLinks(fakeScope).fakeScopeForSignatureDeclaration = kind; + fakeScope.locals = locals; + + setParent(fakeScope, context.enclosingDeclaration); + context.enclosingDeclaration = fakeScope; + } + else { + // We did not create the current scope, so we have to clean it up + return function undo() { + forEach(newLocals, s => locals.delete(s)); + forEach(oldLocals, s => locals.set(s.name, s.oldSymbol)); + }; + } + } + } + + return () => { + cleanupParams?.(); + cleanupTypeParams?.(); + cleanupContext(); + context.enclosingDeclaration = oldEnclosingDecl; + context.mapper = oldMapper; + }; + } + + function tryGetThisParameterDeclaration(signature: Signature, context: NodeBuilderContext) { + if (signature.thisParameter) { + return symbolToParameterDeclaration(signature.thisParameter, context); + } + if (signature.declaration && isInJSFile(signature.declaration)) { + const thisTag = getJSDocThisTag(signature.declaration); + if (thisTag && thisTag.typeExpression) { + return factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + "this", + /*questionToken*/ undefined, + typeToTypeNodeHelper(getTypeFromTypeNode(context, thisTag.typeExpression), context), + ); + } + } + } + + function typeParameterToDeclarationWithConstraint(type: TypeParameter, context: NodeBuilderContext, constraintNode: TypeNode | undefined): TypeParameterDeclaration { + const savedContextFlags = context.flags; + context.flags &= ~NodeBuilderFlags.WriteTypeParametersInQualifiedName; // Avoids potential infinite loop when building for a claimspace with a generic + const modifiers = factory.createModifiersFromModifierFlags(getTypeParameterModifiers(type)); + const name = typeParameterToName(type, context); + const defaultParameter = getDefaultFromTypeParameter(type); + const defaultParameterNode = defaultParameter && typeToTypeNodeHelper(defaultParameter, context); + context.flags = savedContextFlags; + return factory.createTypeParameterDeclaration(modifiers, name, constraintNode, defaultParameterNode); + } + + function typeToTypeNodeHelperWithPossibleReusableTypeNode(type: Type, typeNode: TypeNode | undefined, context: NodeBuilderContext) { + return typeNode && tryReuseExistingNonParameterTypeNode(context, typeNode, type) || typeToTypeNodeHelper(type, context); + } + + function typeParameterToDeclaration(type: TypeParameter, context: NodeBuilderContext, constraint = getConstraintOfTypeParameter(type)): TypeParameterDeclaration { + const constraintNode = constraint && typeToTypeNodeHelperWithPossibleReusableTypeNode(constraint, getConstraintDeclaration(type), context); + return typeParameterToDeclarationWithConstraint(type, context, constraintNode); + } + + function typePredicateToTypePredicateNodeHelper(typePredicate: TypePredicate, context: NodeBuilderContext): TypePredicateNode { + const assertsModifier = typePredicate.kind === TypePredicateKind.AssertsThis || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? + factory.createToken(SyntaxKind.AssertsKeyword) : + undefined; + const parameterName = typePredicate.kind === TypePredicateKind.Identifier || typePredicate.kind === TypePredicateKind.AssertsIdentifier ? + setEmitFlags(factory.createIdentifier(typePredicate.parameterName), EmitFlags.NoAsciiEscaping) : + factory.createThisTypeNode(); + const typeNode = typePredicate.type && typeToTypeNodeHelper(typePredicate.type, context); + return factory.createTypePredicateNode(assertsModifier, parameterName, typeNode); + } + + function getEffectiveParameterDeclaration(parameterSymbol: Symbol): ParameterDeclaration | JSDocParameterTag | undefined { + const parameterDeclaration: ParameterDeclaration | JSDocParameterTag | undefined = getDeclarationOfKind(parameterSymbol, SyntaxKind.Parameter); + if (parameterDeclaration) { + return parameterDeclaration; + } + if (!isTransientSymbol(parameterSymbol)) { + return getDeclarationOfKind(parameterSymbol, SyntaxKind.JSDocParameterTag); + } + } + + function symbolToParameterDeclaration(parameterSymbol: Symbol, context: NodeBuilderContext, preserveModifierFlags?: boolean): ParameterDeclaration { + const parameterDeclaration = getEffectiveParameterDeclaration(parameterSymbol); + + const parameterType = getTypeOfSymbol(parameterSymbol); + const parameterTypeNode = serializeTypeForDeclaration(context, parameterDeclaration, parameterType, parameterSymbol); + + const modifiers = !(context.flags & NodeBuilderFlags.OmitParameterModifiers) && preserveModifierFlags && parameterDeclaration && canHaveModifiers(parameterDeclaration) ? map(getModifiers(parameterDeclaration), factory.cloneNode) : undefined; + const isRest = parameterDeclaration && isRestParameter(parameterDeclaration) || getCheckFlags(parameterSymbol) & CheckFlags.RestParameter; + const dotDotDotToken = isRest ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined; + const name = parameterToParameterDeclarationName(parameterSymbol, parameterDeclaration, context); + const isOptional = parameterDeclaration && isOptionalParameter(parameterDeclaration) || getCheckFlags(parameterSymbol) & CheckFlags.OptionalParameter; + const questionToken = isOptional ? factory.createToken(SyntaxKind.QuestionToken) : undefined; + const parameterNode = factory.createParameterDeclaration( + modifiers, + dotDotDotToken, + name, + questionToken, + parameterTypeNode, + /*initializer*/ undefined, + ); + context.approximateLength += symbolName(parameterSymbol).length + 3; + return parameterNode; + } + + function parameterToParameterDeclarationName(parameterSymbol: Symbol, parameterDeclaration: ParameterDeclaration | JSDocParameterTag | undefined, context: NodeBuilderContext) { + return parameterDeclaration ? parameterDeclaration.name ? + parameterDeclaration.name.kind === SyntaxKind.Identifier ? setEmitFlags(factory.cloneNode(parameterDeclaration.name), EmitFlags.NoAsciiEscaping) : + parameterDeclaration.name.kind === SyntaxKind.QualifiedName ? setEmitFlags(factory.cloneNode(parameterDeclaration.name.right), EmitFlags.NoAsciiEscaping) : + cloneBindingName(parameterDeclaration.name) : + symbolName(parameterSymbol) : + symbolName(parameterSymbol); + + function cloneBindingName(node: BindingName): BindingName { + return elideInitializerAndSetEmitFlags(node) as BindingName; + function elideInitializerAndSetEmitFlags(node: Node): Node { + if (context.tracker.canTrackSymbol && isComputedPropertyName(node) && isLateBindableName(node)) { + trackComputedName(node.expression, context.enclosingDeclaration, context); + } + let visited = visitEachChildWorker(node, elideInitializerAndSetEmitFlags, /*context*/ undefined, /*nodesVisitor*/ undefined, elideInitializerAndSetEmitFlags); + if (isBindingElement(visited)) { + visited = factory.updateBindingElement( + visited, + visited.dotDotDotToken, + visited.propertyName, + visited.name, + /*initializer*/ undefined, + ); + } + if (!nodeIsSynthesized(visited)) { + visited = factory.cloneNode(visited); + } + return setEmitFlags(visited, EmitFlags.SingleLine | EmitFlags.NoAsciiEscaping); + } + } + } + + function trackComputedName(accessExpression: EntityNameOrEntityNameExpression, enclosingDeclaration: Node | undefined, context: NodeBuilderContext) { + if (!context.tracker.canTrackSymbol) return; + // get symbol of the first identifier of the entityName + const firstIdentifier = getFirstIdentifier(accessExpression); + const name = resolveName(firstIdentifier, firstIdentifier.escapedText, SymbolFlags.Value | SymbolFlags.ExportValue, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (name) { + context.tracker.trackSymbol(name, enclosingDeclaration, SymbolFlags.Value); + } + } + + function lookupSymbolChain(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, yieldModuleSymbol?: boolean) { + context.tracker.trackSymbol(symbol, context.enclosingDeclaration, meaning); + return lookupSymbolChainWorker(symbol, context, meaning, yieldModuleSymbol); + } + + function lookupSymbolChainWorker(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, yieldModuleSymbol?: boolean) { + // Try to get qualified name if the symbol is not a type parameter and there is an enclosing declaration. + let chain: Symbol[]; + const isTypeParameter = symbol.flags & SymbolFlags.TypeParameter; + if (!isTypeParameter && (context.enclosingDeclaration || context.flags & NodeBuilderFlags.UseFullyQualifiedType) && !(context.flags & NodeBuilderFlags.DoNotIncludeSymbolChain)) { + chain = Debug.checkDefined(getSymbolChain(symbol, meaning, /*endOfChain*/ true)); + Debug.assert(chain && chain.length > 0); + } + else { + chain = [symbol]; + } + return chain; + + /** @param endOfChain Set to false for recursive calls; non-recursive calls should always output something. */ + function getSymbolChain(symbol: Symbol, meaning: SymbolFlags, endOfChain: boolean): Symbol[] | undefined { + let accessibleSymbolChain = getAccessibleSymbolChain(symbol, context.enclosingDeclaration, meaning, !!(context.flags & NodeBuilderFlags.UseOnlyExternalAliasing)); + let parentSpecifiers: (string | undefined)[]; + if ( + !accessibleSymbolChain || + needsQualification(accessibleSymbolChain[0], context.enclosingDeclaration, accessibleSymbolChain.length === 1 ? meaning : getQualifiedLeftMeaning(meaning)) + ) { + // Go up and add our parent. + const parents = getContainersOfSymbol(accessibleSymbolChain ? accessibleSymbolChain[0] : symbol, context.enclosingDeclaration, meaning); + if (length(parents)) { + parentSpecifiers = parents!.map(symbol => + some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol) + ? getSpecifierForModuleSymbol(symbol, context) + : undefined + ); + const indices = parents!.map((_, i) => i); + indices.sort(sortByBestName); + const sortedParents = indices.map(i => parents![i]); + for (const parent of sortedParents) { + const parentChain = getSymbolChain(parent, getQualifiedLeftMeaning(meaning), /*endOfChain*/ false); + if (parentChain) { + if ( + parent.exports && parent.exports.get(InternalSymbolName.ExportEquals) && + getSymbolIfSameReference(parent.exports.get(InternalSymbolName.ExportEquals)!, symbol) + ) { + // parentChain root _is_ symbol - symbol is a module export=, so it kinda looks like it's own parent + // No need to lookup an alias for the symbol in itself + accessibleSymbolChain = parentChain; + break; + } + accessibleSymbolChain = parentChain.concat(accessibleSymbolChain || [getAliasForSymbolInContainer(parent, symbol) || symbol]); + break; + } + } + } + } + + if (accessibleSymbolChain) { + return accessibleSymbolChain; + } + if ( + // If this is the last part of outputting the symbol, always output. The cases apply only to parent symbols. + endOfChain || + // If a parent symbol is an anonymous type, don't write it. + !(symbol.flags & (SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral)) + ) { + // If a parent symbol is an external module, don't write it. (We prefer just `x` vs `"foo/bar".x`.) + if (!endOfChain && !yieldModuleSymbol && !!forEach(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + return; + } + return [symbol]; + } + + function sortByBestName(a: number, b: number) { + const specifierA = parentSpecifiers[a]; + const specifierB = parentSpecifiers[b]; + if (specifierA && specifierB) { + const isBRelative = pathIsRelative(specifierB); + if (pathIsRelative(specifierA) === isBRelative) { + // Both relative or both non-relative, sort by number of parts + return moduleSpecifiers.countPathComponents(specifierA) - moduleSpecifiers.countPathComponents(specifierB); + } + if (isBRelative) { + // A is non-relative, B is relative: prefer A + return -1; + } + // A is relative, B is non-relative: prefer B + return 1; + } + return 0; + } + } + } + + function typeParametersToTypeParameterDeclarations(symbol: Symbol, context: NodeBuilderContext) { + let typeParameterNodes: NodeArray | undefined; + const targetSymbol = getTargetSymbol(symbol); + if (targetSymbol.flags & (SymbolFlags.Class | SymbolFlags.Interface | SymbolFlags.TypeAlias)) { + typeParameterNodes = factory.createNodeArray(map(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol), tp => typeParameterToDeclaration(tp, context))); + } + return typeParameterNodes; + } + + function lookupTypeParameterNodes(chain: Symbol[], index: number, context: NodeBuilderContext) { + Debug.assert(chain && 0 <= index && index < chain.length); + const symbol = chain[index]; + const symbolId = getSymbolId(symbol); + if (context.typeParameterSymbolList?.has(symbolId)) { + return undefined; + } + if (context.mustCreateTypeParameterSymbolList) { + context.mustCreateTypeParameterSymbolList = false; + context.typeParameterSymbolList = new Set(context.typeParameterSymbolList); + } + context.typeParameterSymbolList!.add(symbolId); + let typeParameterNodes: readonly TypeNode[] | readonly TypeParameterDeclaration[] | undefined; + if (context.flags & NodeBuilderFlags.WriteTypeParametersInQualifiedName && index < (chain.length - 1)) { + const parentSymbol = symbol; + const nextSymbol = chain[index + 1]; + if (getCheckFlags(nextSymbol) & CheckFlags.Instantiated) { + const params = getTypeParametersOfClassOrInterface( + parentSymbol.flags & SymbolFlags.Alias ? resolveAlias(parentSymbol) : parentSymbol, + ); + // NOTE: cast to TransientSymbol should be safe because only TransientSymbol can have CheckFlags.Instantiated + typeParameterNodes = mapToTypeNodes(map(params, t => getMappedType(t, (nextSymbol as TransientSymbol).links.mapper!)), context); + } + else { + typeParameterNodes = typeParametersToTypeParameterDeclarations(symbol, context); + } + } + return typeParameterNodes; + } + + /** + * Given A[B][C][D], finds A[B] + */ + function getTopmostIndexedAccessType(top: IndexedAccessTypeNode): IndexedAccessTypeNode { + if (isIndexedAccessTypeNode(top.objectType)) { + return getTopmostIndexedAccessType(top.objectType); + } + return top; + } + + function getSpecifierForModuleSymbol(symbol: Symbol, context: NodeBuilderContext, overrideImportMode?: ResolutionMode) { + let file = getDeclarationOfKind(symbol, SyntaxKind.SourceFile); + if (!file) { + const equivalentFileSymbol = firstDefined(symbol.declarations, d => getFileSymbolIfFileSymbolExportEqualsContainer(d, symbol)); + if (equivalentFileSymbol) { + file = getDeclarationOfKind(equivalentFileSymbol, SyntaxKind.SourceFile); + } + } + if (file && file.moduleName !== undefined) { + // Use the amd name if it is available + return file.moduleName; + } + if (!file) { + if (ambientModuleSymbolRegex.test(symbol.escapedName as string)) { + return (symbol.escapedName as string).substring(1, (symbol.escapedName as string).length - 1); + } + } + if (!context.enclosingFile || !context.tracker.moduleResolverHost) { + // If there's no context declaration, we can't lookup a non-ambient specifier, so we just use the symbol name + if (ambientModuleSymbolRegex.test(symbol.escapedName as string)) { + return (symbol.escapedName as string).substring(1, (symbol.escapedName as string).length - 1); + } + return getSourceFileOfNode(getNonAugmentationDeclaration(symbol)!).fileName; // A resolver may not be provided for baselines and errors - in those cases we use the fileName in full + } + const contextFile = context.enclosingFile; + const resolutionMode = overrideImportMode || contextFile?.impliedNodeFormat; + const cacheKey = createModeAwareCacheKey(contextFile.path, resolutionMode); + const links = getSymbolLinks(symbol); + let specifier = links.specifierCache && links.specifierCache.get(cacheKey); + if (!specifier) { + const isBundle = !!compilerOptions.outFile; + // For declaration bundles, we need to generate absolute paths relative to the common source dir for imports, + // just like how the declaration emitter does for the ambient module declarations - we can easily accomplish this + // using the `baseUrl` compiler option (which we would otherwise never use in declaration emit) and a non-relative + // specifier preference + const { moduleResolverHost } = context.tracker; + const specifierCompilerOptions = isBundle ? { ...compilerOptions, baseUrl: moduleResolverHost.getCommonSourceDirectory() } : compilerOptions; + specifier = first(moduleSpecifiers.getModuleSpecifiers( + symbol, + checker, + specifierCompilerOptions, + contextFile, + moduleResolverHost, + { + importModuleSpecifierPreference: isBundle ? "non-relative" : "project-relative", + importModuleSpecifierEnding: isBundle ? "minimal" + : resolutionMode === ModuleKind.ESNext ? "js" + : undefined, + }, + { overrideImportMode }, + )); + links.specifierCache ??= new Map(); + links.specifierCache.set(cacheKey, specifier); + } + return specifier; + } + + function symbolToEntityNameNode(symbol: Symbol): EntityName { + const identifier = factory.createIdentifier(unescapeLeadingUnderscores(symbol.escapedName)); + return symbol.parent ? factory.createQualifiedName(symbolToEntityNameNode(symbol.parent), identifier) : identifier; + } + + function symbolToTypeNode(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, overrideTypeArguments?: readonly TypeNode[]): TypeNode { + const chain = lookupSymbolChain(symbol, context, meaning, !(context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope)); // If we're using aliases outside the current scope, dont bother with the module + + const isTypeOf = meaning === SymbolFlags.Value; + if (some(chain[0].declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + // module is root, must use `ImportTypeNode` + const nonRootParts = chain.length > 1 ? createAccessFromSymbolChain(chain, chain.length - 1, 1) : undefined; + const typeParameterNodes = overrideTypeArguments || lookupTypeParameterNodes(chain, 0, context); + const contextFile = getSourceFileOfNode(getOriginalNode(context.enclosingDeclaration)); + const targetFile = getSourceFileOfModule(chain[0]); + let specifier: string | undefined; + let attributes: ImportAttributes | undefined; + if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) { + // An `import` type directed at an esm format file is only going to resolve in esm mode - set the esm mode assertion + if (targetFile?.impliedNodeFormat === ModuleKind.ESNext && targetFile.impliedNodeFormat !== contextFile?.impliedNodeFormat) { + specifier = getSpecifierForModuleSymbol(chain[0], context, ModuleKind.ESNext); + attributes = factory.createImportAttributes( + factory.createNodeArray([ + factory.createImportAttribute( + factory.createStringLiteral("resolution-mode"), + factory.createStringLiteral("import"), + ), + ]), + ); + } + } + if (!specifier) { + specifier = getSpecifierForModuleSymbol(chain[0], context); + } + if (!(context.flags & NodeBuilderFlags.AllowNodeModulesRelativePaths) && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Classic && specifier.includes("/node_modules/")) { + const oldSpecifier = specifier; + if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) { + // We might be able to write a portable import type using a mode override; try specifier generation again, but with a different mode set + const swappedMode = contextFile?.impliedNodeFormat === ModuleKind.ESNext ? ModuleKind.CommonJS : ModuleKind.ESNext; + specifier = getSpecifierForModuleSymbol(chain[0], context, swappedMode); + + if (specifier.includes("/node_modules/")) { + // Still unreachable :( + specifier = oldSpecifier; + } + else { + attributes = factory.createImportAttributes( + factory.createNodeArray([ + factory.createImportAttribute( + factory.createStringLiteral("resolution-mode"), + factory.createStringLiteral(swappedMode === ModuleKind.ESNext ? "import" : "require"), + ), + ]), + ); + } + } + + if (!attributes) { + // If ultimately we can only name the symbol with a reference that dives into a `node_modules` folder, we should error + // since declaration files with these kinds of references are liable to fail when published :( + context.encounteredError = true; + if (context.tracker.reportLikelyUnsafeImportRequiredError) { + context.tracker.reportLikelyUnsafeImportRequiredError(oldSpecifier); + } + } + } + const lit = factory.createLiteralTypeNode(factory.createStringLiteral(specifier)); + context.approximateLength += specifier.length + 10; // specifier + import("") + if (!nonRootParts || isEntityName(nonRootParts)) { + if (nonRootParts) { + const lastId = isIdentifier(nonRootParts) ? nonRootParts : nonRootParts.right; + setIdentifierTypeArguments(lastId, /*typeArguments*/ undefined); + } + return factory.createImportTypeNode(lit, attributes, nonRootParts as EntityName, typeParameterNodes as readonly TypeNode[], isTypeOf); + } + else { + const splitNode = getTopmostIndexedAccessType(nonRootParts); + const qualifier = (splitNode.objectType as TypeReferenceNode).typeName; + return factory.createIndexedAccessTypeNode(factory.createImportTypeNode(lit, attributes, qualifier, typeParameterNodes as readonly TypeNode[], isTypeOf), splitNode.indexType); + } + } + + const entityName = createAccessFromSymbolChain(chain, chain.length - 1, 0); + if (isIndexedAccessTypeNode(entityName)) { + return entityName; // Indexed accesses can never be `typeof` + } + if (isTypeOf) { + return factory.createTypeQueryNode(entityName); + } + else { + const lastId = isIdentifier(entityName) ? entityName : entityName.right; + const lastTypeArgs = getIdentifierTypeArguments(lastId); + setIdentifierTypeArguments(lastId, /*typeArguments*/ undefined); + return factory.createTypeReferenceNode(entityName, lastTypeArgs as NodeArray); + } + + function createAccessFromSymbolChain(chain: Symbol[], index: number, stopper: number): EntityName | IndexedAccessTypeNode { + const typeParameterNodes = index === (chain.length - 1) ? overrideTypeArguments : lookupTypeParameterNodes(chain, index, context); + const symbol = chain[index]; + const parent = chain[index - 1]; + + let symbolName: string | undefined; + if (index === 0) { + context.flags |= NodeBuilderFlags.InInitialEntityName; + symbolName = getNameOfSymbolAsWritten(symbol, context); + context.approximateLength += (symbolName ? symbolName.length : 0) + 1; + context.flags ^= NodeBuilderFlags.InInitialEntityName; + } + else { + if (parent && getExportsOfSymbol(parent)) { + const exports = getExportsOfSymbol(parent); + forEachEntry(exports, (ex, name) => { + if (getSymbolIfSameReference(ex, symbol) && !isLateBoundName(name) && name !== InternalSymbolName.ExportEquals) { + symbolName = unescapeLeadingUnderscores(name); + return true; + } + }); + } + } + + if (symbolName === undefined) { + const name = firstDefined(symbol.declarations, getNameOfDeclaration); + if (name && isComputedPropertyName(name) && isEntityName(name.expression)) { + const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); + if (isEntityName(LHS)) { + return factory.createIndexedAccessTypeNode(factory.createParenthesizedType(factory.createTypeQueryNode(LHS)), factory.createTypeQueryNode(name.expression)); + } + return LHS; + } + symbolName = getNameOfSymbolAsWritten(symbol, context); + } + context.approximateLength += symbolName.length + 1; + + if ( + !(context.flags & NodeBuilderFlags.ForbidIndexedAccessSymbolReferences) && parent && + getMembersOfSymbol(parent) && getMembersOfSymbol(parent).get(symbol.escapedName) && + getSymbolIfSameReference(getMembersOfSymbol(parent).get(symbol.escapedName)!, symbol) + ) { + // Should use an indexed access + const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); + if (isIndexedAccessTypeNode(LHS)) { + return factory.createIndexedAccessTypeNode(LHS, factory.createLiteralTypeNode(factory.createStringLiteral(symbolName))); + } + else { + return factory.createIndexedAccessTypeNode(factory.createTypeReferenceNode(LHS, typeParameterNodes as readonly TypeNode[]), factory.createLiteralTypeNode(factory.createStringLiteral(symbolName))); + } + } + + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + + if (index > stopper) { + const LHS = createAccessFromSymbolChain(chain, index - 1, stopper); + if (!isEntityName(LHS)) { + return Debug.fail("Impossible construct - an export of an indexed access cannot be reachable"); + } + return factory.createQualifiedName(LHS, identifier); + } + return identifier; + } + } + + function typeParameterShadowsOtherTypeParameterInScope(escapedName: __String, context: NodeBuilderContext, type: TypeParameter) { + const result = resolveName(context.enclosingDeclaration, escapedName, SymbolFlags.Type, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (result && result.flags & SymbolFlags.TypeParameter) { + return result !== type.symbol; + } + return false; + } + + function typeParameterToName(type: TypeParameter, context: NodeBuilderContext) { + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams && context.typeParameterNames) { + const cached = context.typeParameterNames.get(getTypeId(type)); + if (cached) { + return cached; + } + } + let result = symbolToName(type.symbol, context, SymbolFlags.Type, /*expectsIdentifier*/ true); + if (!(result.kind & SyntaxKind.Identifier)) { + return factory.createIdentifier("(Missing type parameter)"); + } + const decl = type.symbol?.declarations?.[0]; + if (decl && isTypeParameterDeclaration(decl)) { + result = setTextRange(context, result, decl.name); + } + if (context.flags & NodeBuilderFlags.GenerateNamesForShadowedTypeParams) { + const rawtext = result.escapedText as string; + let i = context.typeParameterNamesByTextNextNameCount?.get(rawtext) || 0; + let text = rawtext; + while (context.typeParameterNamesByText?.has(text) || typeParameterShadowsOtherTypeParameterInScope(text as __String, context, type)) { + i++; + text = `${rawtext}_${i}`; + } + if (text !== rawtext) { + const typeArguments = getIdentifierTypeArguments(result); + result = factory.createIdentifier(text); + setIdentifierTypeArguments(result, typeArguments); + } + if (context.mustCreateTypeParametersNamesLookups) { + context.mustCreateTypeParametersNamesLookups = false; + context.typeParameterNames = new Map(context.typeParameterNames); + context.typeParameterNamesByTextNextNameCount = new Map(context.typeParameterNamesByTextNextNameCount); + context.typeParameterNamesByText = new Set(context.typeParameterNamesByText); + } + // avoiding iterations of the above loop turns out to be worth it when `i` starts to get large, so we cache the max + // `i` we've used thus far, to save work later + context.typeParameterNamesByTextNextNameCount!.set(rawtext, i); + context.typeParameterNames!.set(getTypeId(type), result); + context.typeParameterNamesByText!.add(text); + } + return result; + } + + function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: true): Identifier; + function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: false): EntityName; + function symbolToName(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags, expectsIdentifier: boolean): EntityName { + const chain = lookupSymbolChain(symbol, context, meaning); + + if ( + expectsIdentifier && chain.length !== 1 + && !context.encounteredError + && !(context.flags & NodeBuilderFlags.AllowQualifiedNameInPlaceOfIdentifier) + ) { + context.encounteredError = true; + } + return createEntityNameFromSymbolChain(chain, chain.length - 1); + + function createEntityNameFromSymbolChain(chain: Symbol[], index: number): EntityName { + const typeParameterNodes = lookupTypeParameterNodes(chain, index, context); + const symbol = chain[index]; + + if (index === 0) { + context.flags |= NodeBuilderFlags.InInitialEntityName; + } + const symbolName = getNameOfSymbolAsWritten(symbol, context); + if (index === 0) { + context.flags ^= NodeBuilderFlags.InInitialEntityName; + } + + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + + return index > 0 ? factory.createQualifiedName(createEntityNameFromSymbolChain(chain, index - 1), identifier) : identifier; + } + } + + function symbolToExpression(symbol: Symbol, context: NodeBuilderContext, meaning: SymbolFlags) { + const chain = lookupSymbolChain(symbol, context, meaning); + + return createExpressionFromSymbolChain(chain, chain.length - 1); + + function createExpressionFromSymbolChain(chain: Symbol[], index: number): Expression { + const typeParameterNodes = lookupTypeParameterNodes(chain, index, context); + const symbol = chain[index]; + + if (index === 0) { + context.flags |= NodeBuilderFlags.InInitialEntityName; + } + let symbolName = getNameOfSymbolAsWritten(symbol, context); + if (index === 0) { + context.flags ^= NodeBuilderFlags.InInitialEntityName; + } + let firstChar = symbolName.charCodeAt(0); + + if (isSingleOrDoubleQuote(firstChar) && some(symbol.declarations, hasNonGlobalAugmentationExternalModuleSymbol)) { + return factory.createStringLiteral(getSpecifierForModuleSymbol(symbol, context)); + } + if (index === 0 || canUsePropertyAccess(symbolName, languageVersion)) { + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + + return index > 0 ? factory.createPropertyAccessExpression(createExpressionFromSymbolChain(chain, index - 1), identifier) : identifier; + } + else { + if (firstChar === CharacterCodes.openBracket) { + symbolName = symbolName.substring(1, symbolName.length - 1); + firstChar = symbolName.charCodeAt(0); + } + let expression: Expression | undefined; + if (isSingleOrDoubleQuote(firstChar) && !(symbol.flags & SymbolFlags.EnumMember)) { + expression = factory.createStringLiteral(stripQuotes(symbolName).replace(/\\./g, s => s.substring(1)), firstChar === CharacterCodes.singleQuote); + } + else if (("" + +symbolName) === symbolName) { + expression = factory.createNumericLiteral(+symbolName); + } + if (!expression) { + const identifier = setEmitFlags(factory.createIdentifier(symbolName), EmitFlags.NoAsciiEscaping); + if (typeParameterNodes) setIdentifierTypeArguments(identifier, factory.createNodeArray(typeParameterNodes)); + identifier.symbol = symbol; + expression = identifier; + } + return factory.createElementAccessExpression(createExpressionFromSymbolChain(chain, index - 1), expression); + } + } + } + + function isStringNamed(d: Declaration) { + const name = getNameOfDeclaration(d); + if (!name) { + return false; + } + if (isComputedPropertyName(name)) { + const type = checkExpression(name.expression); + return !!(type.flags & TypeFlags.StringLike); + } + if (isElementAccessExpression(name)) { + const type = checkExpression(name.argumentExpression); + return !!(type.flags & TypeFlags.StringLike); + } + return isStringLiteral(name); + } + + function isSingleQuotedStringNamed(d: Declaration) { + const name = getNameOfDeclaration(d); + return !!(name && isStringLiteral(name) && (name.singleQuote || !nodeIsSynthesized(name) && startsWith(getTextOfNode(name, /*includeTrivia*/ false), "'"))); + } + + function getPropertyNameNodeForSymbol(symbol: Symbol, context: NodeBuilderContext) { + const stringNamed = !!length(symbol.declarations) && every(symbol.declarations, isStringNamed); + const singleQuote = !!length(symbol.declarations) && every(symbol.declarations, isSingleQuotedStringNamed); + const isMethod = !!(symbol.flags & SymbolFlags.Method); + const fromNameType = getPropertyNameNodeForSymbolFromNameType(symbol, context, singleQuote, stringNamed, isMethod); + if (fromNameType) { + return fromNameType; + } + const rawName = unescapeLeadingUnderscores(symbol.escapedName); + return createPropertyNameNodeForIdentifierOrLiteral(rawName, getEmitScriptTarget(compilerOptions), singleQuote, stringNamed, isMethod); + } + + // See getNameForSymbolFromNameType for a stringy equivalent + function getPropertyNameNodeForSymbolFromNameType(symbol: Symbol, context: NodeBuilderContext, singleQuote: boolean, stringNamed: boolean, isMethod: boolean) { + const nameType = getSymbolLinks(symbol).nameType; + if (nameType) { + if (nameType.flags & TypeFlags.StringOrNumberLiteral) { + const name = "" + (nameType as StringLiteralType | NumberLiteralType).value; + if (!isIdentifierText(name, getEmitScriptTarget(compilerOptions)) && (stringNamed || !isNumericLiteralName(name))) { + return factory.createStringLiteral(name, !!singleQuote); + } + if (isNumericLiteralName(name) && startsWith(name, "-")) { + return factory.createComputedPropertyName(factory.createPrefixUnaryExpression(SyntaxKind.MinusToken, factory.createNumericLiteral(-name))); + } + return createPropertyNameNodeForIdentifierOrLiteral(name, getEmitScriptTarget(compilerOptions), singleQuote, stringNamed, isMethod); + } + if (nameType.flags & TypeFlags.UniqueESSymbol) { + return factory.createComputedPropertyName(symbolToExpression((nameType as UniqueESSymbolType).symbol, context, SymbolFlags.Value)); + } + } + } + + function cloneNodeBuilderContext(context: NodeBuilderContext) { + // Make type parameters created within this context not consume the name outside this context + // The symbol serializer ends up creating many sibling scopes that all need "separate" contexts when + // it comes to naming things - within a normal `typeToTypeNode` call, the node builder only ever descends + // through the type tree, so the only cases where we could have used distinct sibling scopes was when there + // were multiple generic overloads with similar generated type parameter names + // The effect: + // When we write out + // export const x: (x: T) => T + // export const y: (x: T) => T + // we write it out like that, rather than as + // export const x: (x: T) => T + // export const y: (x: T_1) => T_1 + const oldMustCreateTypeParameterSymbolList = context.mustCreateTypeParameterSymbolList; + const oldMustCreateTypeParametersNamesLookups = context.mustCreateTypeParametersNamesLookups; + context.mustCreateTypeParameterSymbolList = true; + context.mustCreateTypeParametersNamesLookups = true; + const oldTypeParameterNames = context.typeParameterNames; + const oldTypeParameterNamesByText = context.typeParameterNamesByText; + const oldTypeParameterNamesByTextNextNameCount = context.typeParameterNamesByTextNextNameCount; + const oldTypeParameterSymbolList = context.typeParameterSymbolList; + return () => { + context.typeParameterNames = oldTypeParameterNames; + context.typeParameterNamesByText = oldTypeParameterNamesByText; + context.typeParameterNamesByTextNextNameCount = oldTypeParameterNamesByTextNextNameCount; + context.typeParameterSymbolList = oldTypeParameterSymbolList; + context.mustCreateTypeParameterSymbolList = oldMustCreateTypeParameterSymbolList; + context.mustCreateTypeParametersNamesLookups = oldMustCreateTypeParametersNamesLookups; + }; + } + + function getDeclarationWithTypeAnnotation(symbol: Symbol, enclosingDeclaration?: Node | undefined) { + return symbol.declarations && find(symbol.declarations, s => !!getNonlocalEffectiveTypeAnnotationNode(s) && (!enclosingDeclaration || !!findAncestor(s, n => n === enclosingDeclaration))); + } + + function existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing: TypeNode, type: Type) { + // In JS, you can say something like `Foo` and get a `Foo` implicitly - we don't want to preserve that original `Foo` in these cases, though. + if (!(getObjectFlags(type) & ObjectFlags.Reference)) return true; + if (!isTypeReferenceNode(existing)) return true; + // `type` is a reference type, and `existing` is a type reference node, but we still need to make sure they refer to the _same_ target type + // before we go comparing their type argument counts. + void getTypeFromTypeReference(existing); // call to ensure symbol is resolved + const symbol = getNodeLinks(existing).resolvedSymbol; + const existingTarget = symbol && getDeclaredTypeOfSymbol(symbol); + if (!existingTarget || existingTarget !== (type as TypeReference).target) return true; + return length(existing.typeArguments) >= getMinTypeArgumentCount((type as TypeReference).target.typeParameters); + } + + function getEnclosingDeclarationIgnoringFakeScope(enclosingDeclaration: Node) { + while (getNodeLinks(enclosingDeclaration).fakeScopeForSignatureDeclaration) { + enclosingDeclaration = enclosingDeclaration.parent; + } + return enclosingDeclaration; + } + + /** + * Unlike `typeToTypeNodeHelper`, this handles setting up the `AllowUniqueESSymbolType` flag + * so a `unique symbol` is returned when appropriate for the input symbol, rather than `typeof sym` + * @param context - The node builder context. Any reused nodes are checked to be pulled from within the scope of the context's enclosingDeclaration. + * @param declaration - The preferred declaration to pull existing type nodes from (the symbol will be used as a fallback to find any annotated declaration) + * @param type - The type to write; an existing annotation must match this type if it's used, otherwise this is the type serialized as a new type node + * @param symbol - The symbol is used both to find an existing annotation if declaration is not provided, and to determine if `unique symbol` should be printed + */ + function serializeTypeForDeclaration(context: NodeBuilderContext, declaration: Declaration | undefined, type: Type, symbol: Symbol) { + const addUndefined = declaration && (isParameter(declaration) || isJSDocParameterTag(declaration)) && requiresAddingImplicitUndefined(declaration); + const enclosingDeclaration = context.enclosingDeclaration; + const oldFlags = context.flags; + if (declaration && hasInferredType(declaration) && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) { + syntacticNodeBuilder.serializeTypeOfDeclaration(declaration, context); + } + context.flags |= NodeBuilderFlags.NoSyntacticPrinter; + if (enclosingDeclaration && (!isErrorType(type) || (context.flags & NodeBuilderFlags.AllowUnresolvedNames))) { + const declWithExistingAnnotation = declaration && getNonlocalEffectiveTypeAnnotationNode(declaration) + ? declaration + : getDeclarationWithTypeAnnotation(symbol); + if (declWithExistingAnnotation && !isFunctionLikeDeclaration(declWithExistingAnnotation) && !isGetAccessorDeclaration(declWithExistingAnnotation)) { + // try to reuse the existing annotation + const existing = getNonlocalEffectiveTypeAnnotationNode(declWithExistingAnnotation)!; + const result = !isTypePredicateNode(existing) && tryReuseExistingTypeNode(context, existing, type, declWithExistingAnnotation, addUndefined); + if (result) { + context.flags = oldFlags; + return result; + } + } + } + if ( + type.flags & TypeFlags.UniqueESSymbol && + type.symbol === symbol && (!context.enclosingDeclaration || some(symbol.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(context.enclosingDeclaration!))) + ) { + context.flags |= NodeBuilderFlags.AllowUniqueESSymbolType; + } + + const decl = declaration ?? symbol.valueDeclaration ?? symbol.declarations?.[0]; + const expr = decl && isDeclarationWithPossibleInnerTypeNodeReuse(decl) ? getPossibleTypeNodeReuseExpression(decl) : undefined; + + const result = expressionOrTypeToTypeNode(context, expr, type, addUndefined); + context.flags = oldFlags; + return result; + } + + function typeNodeIsEquivalentToType(annotatedDeclaration: Node | undefined, type: Type, typeFromTypeNode: Type) { + if (typeFromTypeNode === type) { + return true; + } + if (annotatedDeclaration && (isParameter(annotatedDeclaration) || isPropertySignature(annotatedDeclaration) || isPropertyDeclaration(annotatedDeclaration)) && annotatedDeclaration.questionToken) { + return getTypeWithFacts(type, TypeFacts.NEUndefined) === typeFromTypeNode; + } + return false; + } + + function serializeReturnTypeForSignature(context: NodeBuilderContext, signature: Signature) { + const suppressAny = context.flags & NodeBuilderFlags.SuppressAnyReturnType; + const flags = context.flags; + if (suppressAny) context.flags &= ~NodeBuilderFlags.SuppressAnyReturnType; // suppress only toplevel `any`s + let returnTypeNode: TypeNode | undefined; + const returnType = getReturnTypeOfSignature(signature); + if (returnType && !(suppressAny && isTypeAny(returnType))) { + if (signature.declaration && !(context.flags & NodeBuilderFlags.NoSyntacticPrinter)) { + syntacticNodeBuilder.serializeReturnTypeForSignature(signature.declaration, context); + } + context.flags |= NodeBuilderFlags.NoSyntacticPrinter; + returnTypeNode = serializeReturnTypeForSignatureWorker(context, signature); + } + else if (!suppressAny) { + returnTypeNode = factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + context.flags = flags; + return returnTypeNode; + } + + function serializeReturnTypeForSignatureWorker(context: NodeBuilderContext, signature: Signature) { + const typePredicate = getTypePredicateOfSignature(signature); + const type = getReturnTypeOfSignature(signature); + if (context.enclosingDeclaration && (!isErrorType(type) || (context.flags & NodeBuilderFlags.AllowUnresolvedNames)) && signature.declaration && !nodeIsSynthesized(signature.declaration)) { + const annotation = signature.declaration && getNonlocalEffectiveReturnTypeAnnotationNode(signature.declaration); + // Default constructor signatures inherited from base classes return the derived class but have the base class declaration + // To ensure we don't serialize the wrong type we check that that return type of the signature corresponds to the declaration return type signature + if (annotation && getTypeFromTypeNode(context, annotation) === type) { + const result = tryReuseExistingTypeNodeHelper(context, annotation); + if (result) { + return result; + } + } + } + if (typePredicate) { + return typePredicateToTypePredicateNodeHelper(typePredicate, context); + } + const expr = signature.declaration && getPossibleTypeNodeReuseExpression(signature.declaration); + return expressionOrTypeToTypeNode(context, expr, type); + } + + function trackExistingEntityName(node: T, context: NodeBuilderContext) { + let introducesError = false; + const leftmost = getFirstIdentifier(node); + if (isInJSFile(node) && (isExportsIdentifier(leftmost) || isModuleExportsAccessExpression(leftmost.parent) || (isQualifiedName(leftmost.parent) && isModuleIdentifier(leftmost.parent.left) && isExportsIdentifier(leftmost.parent.right)))) { + introducesError = true; + return { introducesError, node }; + } + const meaning = getMeaningOfEntityNameReference(node); + let sym: Symbol | undefined; + if (isThisIdentifier(leftmost)) { + // `this` isn't a bindable identifier - skip resolution, find a relevant `this` symbol directly and avoid exhaustive scope traversal + sym = getSymbolOfDeclaration(getThisContainer(leftmost, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)); + if (isSymbolAccessible(sym, leftmost, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible) { + introducesError = true; + context.tracker.reportInaccessibleThisError(); + } + return { introducesError, node: attachSymbolToLeftmostIdentifier(node) as T }; + } + sym = resolveEntityName(leftmost, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true); + if ( + context.enclosingDeclaration && + !(sym && sym.flags & SymbolFlags.TypeParameter) + ) { + sym = getExportSymbolOfValueSymbolIfExported(sym); + // Some declarations may be transplanted to a new location. + // When this happens we need to make sure that the name has the same meaning at both locations + // We also check for the unknownSymbol because when we create a fake scope some parameters may actually not be usable + // either because they are the expanded rest parameter, + // or because they are the newly added parameters from the tuple, which might have different meanings in the original context + const symAtLocation = resolveEntityName(leftmost, meaning, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, context.enclosingDeclaration); + if ( + // Check for unusable parameters symbols + symAtLocation === unknownSymbol || + // If the symbol is not found, but was not found in the original scope either we probably have an error, don't reuse the node + (symAtLocation === undefined && sym !== undefined) || + // If the symbol is found both in declaration scope and in current scope then it shoudl point to the same reference + (symAtLocation && sym && !getSymbolIfSameReference(getExportSymbolOfValueSymbolIfExported(symAtLocation), sym)) + ) { + // In isolated declaration we will not do rest parameter expansion so there is no need to report on these. + if (symAtLocation !== unknownSymbol) { + context.tracker.reportInferenceFallback(node); + } + introducesError = true; + return { introducesError, node, sym }; + } + } + + if (sym) { + // If a parameter is resolvable in the current context it is also visible, so no need to go to symbol accesibility + if ( + sym.flags & SymbolFlags.FunctionScopedVariable + && sym.valueDeclaration + ) { + if (isPartOfParameterDeclaration(sym.valueDeclaration) || isJSDocParameterTag(sym.valueDeclaration)) { + return { introducesError, node: attachSymbolToLeftmostIdentifier(node) as T }; + } + } + if ( + !(sym.flags & SymbolFlags.TypeParameter) && // Type parameters are visible in the current context if they are are resolvable + !isDeclarationName(node) && + isSymbolAccessible(sym, context.enclosingDeclaration, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible + ) { + context.tracker.reportInferenceFallback(node); + introducesError = true; + } + else { + context.tracker.trackSymbol(sym, context.enclosingDeclaration, meaning); + } + return { introducesError, node: attachSymbolToLeftmostIdentifier(node) as T }; + } + + return { introducesError, node }; + + /** + * Attaches a `.symbol` member to an identifier, cloning it to do so, so symbol information + * is smuggled out for symbol display information. + */ + function attachSymbolToLeftmostIdentifier(node: Node): Node { + if (node === leftmost) { + const type = getDeclaredTypeOfSymbol(sym!); + const name = sym!.flags & SymbolFlags.TypeParameter ? typeParameterToName(type, context) : factory.cloneNode(node as Identifier); + name.symbol = sym!; // for quickinfo, which uses identifier symbol information + return setTextRange(context, setEmitFlags(name, EmitFlags.NoAsciiEscaping), node); + } + const updated = visitEachChildWorker(node, c => attachSymbolToLeftmostIdentifier(c), /*context*/ undefined); + if (updated !== node) { + setTextRange(context, updated, node); + } + return updated; + } + } + + function serializeTypeName(context: NodeBuilderContext, node: EntityName, isTypeOf?: boolean, typeArguments?: readonly TypeNode[]) { + const meaning = isTypeOf ? SymbolFlags.Value : SymbolFlags.Type; + const symbol = resolveEntityName(node, meaning, /*ignoreErrors*/ true); + if (!symbol) return undefined; + const resolvedSymbol = symbol.flags & SymbolFlags.Alias ? resolveAlias(symbol) : symbol; + if (isSymbolAccessible(symbol, context.enclosingDeclaration, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility !== SymbolAccessibility.Accessible) return undefined; + return symbolToTypeNode(resolvedSymbol, context, meaning, typeArguments); + } + + function canReuseTypeNode(context: NodeBuilderContext, existing: TypeNode) { + if (isInJSFile(existing)) { + if (isLiteralImportTypeNode(existing)) { + // Ensure resolvedSymbol is present + void getTypeFromImportTypeNode(existing); + const nodeSymbol = getNodeLinks(existing).resolvedSymbol; + return ( + !nodeSymbol || + !( + // The import type resolved using jsdoc fallback logic + (!existing.isTypeOf && !(nodeSymbol.flags & SymbolFlags.Type)) || + // The import type had type arguments autofilled by js fallback logic + !(length(existing.typeArguments) >= getMinTypeArgumentCount(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(nodeSymbol))) + ) + ); + } + } + if (isThisTypeNode(existing)) { + if (context.mapper === undefined) return true; + const type = getTypeFromTypeNode(context, existing, /*noMappedTypes*/ true); + return !!type; + } + if (isTypeReferenceNode(existing)) { + if (isConstTypeReference(existing)) return false; + const type = getTypeFromTypeReference(existing); + const symbol = getNodeLinks(existing).resolvedSymbol; + if (!symbol) return false; + if (symbol.flags & SymbolFlags.TypeParameter) { + const type = getDeclaredTypeOfSymbol(symbol); + if (context.mapper && getMappedType(type, context.mapper) !== type) { + return false; + } + } + if (isInJSDoc(existing)) { + return existingTypeNodeIsNotReferenceOrIsReferenceWithCompatibleTypeArgumentCount(existing, type) + && !getIntendedTypeFromJSDocTypeReference(existing) // We should probably allow the reuse of JSDoc reference types such as String Number etc + && (symbol.flags & SymbolFlags.Type); // JSDoc type annotations can reference values (meaning typeof value) as well as types. We only reuse type nodes + } + } + if ( + isTypeOperatorNode(existing) && + existing.operator === SyntaxKind.UniqueKeyword && + existing.type.kind === SyntaxKind.SymbolKeyword + ) { + const effectiveEnclosingContext = context.enclosingDeclaration && getEnclosingDeclarationIgnoringFakeScope(context.enclosingDeclaration); + return !!findAncestor(existing, n => n === effectiveEnclosingContext); + } + return true; + } + + function serializeExistingTypeNode(context: NodeBuilderContext, typeNode: TypeNode) { + const type = getTypeFromTypeNode(context, typeNode); + return typeToTypeNodeHelper(type, context); + } + + /** + * Do you mean to call this directly? You probably should use `tryReuseExistingTypeNode` instead, + * which performs sanity checking on the type before doing this. + */ + function tryReuseExistingTypeNodeHelper(context: NodeBuilderContext, existing: TypeNode) { + if (cancellationToken && cancellationToken.throwIfCancellationRequested) { + cancellationToken.throwIfCancellationRequested(); + } + let hadError = false; + const { finalizeBoundary, startRecoveryScope } = createRecoveryBoundary(); + const transformed = visitNode(existing, visitExistingNodeTreeSymbols, isTypeNode); + if (!finalizeBoundary()) { + return undefined; + } + context.approximateLength += existing.end - existing.pos; + return transformed; + + function visitExistingNodeTreeSymbols(node: Node): Node | undefined { + // If there was an error in a sibling node bail early, the result will be discarded anyway + if (hadError) return node; + const recover = startRecoveryScope(); + const onExitNewScope = isNewScopeNode(node) ? onEnterNewScope(node) : undefined; + const result = visitExistingNodeTreeSymbolsWorker(node); + onExitNewScope?.(); + + // If there was an error, maybe we can recover by serializing the actual type of the node + if (hadError) { + if (isTypeNode(node) && !isTypePredicateNode(node)) { + recover(); + return serializeExistingTypeNode(context, node); + } + return node; + } + // We want to clone the subtree, so when we mark it up with __pos and __end in quickfixes, + // we don't get odd behavior because of reused nodes. We also need to clone to _remove_ + // the position information if the node comes from a different file than the one the node builder + // is set to build for (even though we are reusing the node structure, the position information + // would make the printer print invalid spans for literals and identifiers, and the formatter would + // choke on the mismatched positonal spans between a parent and an injected child from another file). + return result ? setTextRange(context, result, node) : undefined; + } + + function createRecoveryBoundary() { + let trackedSymbols: TrackedSymbol[]; + let unreportedErrors: (() => void)[]; + const oldTracker = context.tracker; + const oldTrackedSymbols = context.trackedSymbols; + context.trackedSymbols = undefined; + const oldEncounteredError = context.encounteredError; + context.tracker = new SymbolTrackerImpl(context, { + ...oldTracker.inner, + reportCyclicStructureError() { + markError(() => oldTracker.reportCyclicStructureError()); + }, + reportInaccessibleThisError() { + markError(() => oldTracker.reportInaccessibleThisError()); + }, + reportInaccessibleUniqueSymbolError() { + markError(() => oldTracker.reportInaccessibleUniqueSymbolError()); + }, + reportLikelyUnsafeImportRequiredError(specifier) { + markError(() => oldTracker.reportLikelyUnsafeImportRequiredError(specifier)); + }, + reportNonSerializableProperty(name) { + markError(() => oldTracker.reportNonSerializableProperty(name)); + }, + trackSymbol(sym, decl, meaning) { + (trackedSymbols ??= []).push([sym, decl, meaning]); + return false; + }, + moduleResolverHost: context.tracker.moduleResolverHost, + }, context.tracker.moduleResolverHost); + + return { + startRecoveryScope, + finalizeBoundary, + }; + + function markError(unreportedError: () => void) { + hadError = true; + (unreportedErrors ??= []).push(unreportedError); + } + + function startRecoveryScope() { + const trackedSymbolsTop = trackedSymbols?.length ?? 0; + const unreportedErrorsTop = unreportedErrors?.length ?? 0; + return () => { + hadError = false; + // Reset the tracked symbols to before the error + if (trackedSymbols) { + trackedSymbols.length = trackedSymbolsTop; + } + if (unreportedErrors) { + unreportedErrors.length = unreportedErrorsTop; + } + }; + } + + function finalizeBoundary() { + context.tracker = oldTracker; + context.trackedSymbols = oldTrackedSymbols; + context.encounteredError = oldEncounteredError; + + unreportedErrors?.forEach(fn => fn()); + if (hadError) { + return false; + } + trackedSymbols?.forEach( + ([symbol, enclosingDeclaration, meaning]) => + context.tracker.trackSymbol( + symbol, + enclosingDeclaration, + meaning, + ), + ); + return true; + } + } + function onEnterNewScope(node: IntroducesNewScopeNode | ConditionalTypeNode) { + return enterNewScope(context, node, getParametersInScope(node), getTypeParametersInScope(node)); + } + + function tryVisitSimpleTypeNode(node: TypeNode): TypeNode | undefined { + const innerNode = skipTypeParentheses(node); + switch (innerNode.kind) { + case SyntaxKind.TypeReference: + return tryVisitTypeReference(innerNode as TypeReferenceNode); + case SyntaxKind.TypeQuery: + return tryVisitTypeQuery(innerNode as TypeQueryNode); + case SyntaxKind.IndexedAccessType: + return tryVisitIndexedAccess(innerNode as IndexedAccessTypeNode); + case SyntaxKind.TypeOperator: + const typeOperatorNode = innerNode as TypeOperatorNode; + if (typeOperatorNode.operator === SyntaxKind.KeyOfKeyword) { + return tryVisitKeyOf(typeOperatorNode); + } + } + return visitNode(node, visitExistingNodeTreeSymbols, isTypeNode); + } + + function tryVisitIndexedAccess(node: IndexedAccessTypeNode): TypeNode | undefined { + const resultObjectType = tryVisitSimpleTypeNode(node.objectType); + if (resultObjectType === undefined) { + return undefined; + } + return factory.updateIndexedAccessTypeNode(node, resultObjectType, visitNode(node.indexType, visitExistingNodeTreeSymbols, isTypeNode)!); + } + + function tryVisitKeyOf(node: TypeOperatorNode): TypeNode | undefined { + Debug.assertEqual(node.operator, SyntaxKind.KeyOfKeyword); + const type = tryVisitSimpleTypeNode(node.type); + if (type === undefined) { + return undefined; + } + return factory.updateTypeOperatorNode(node, type); + } + + function tryVisitTypeQuery(node: TypeQueryNode): TypeNode | undefined { + const { introducesError, node: exprName } = trackExistingEntityName(node.exprName, context); + if (!introducesError) { + return factory.updateTypeQueryNode( + node, + exprName, + visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode), + ); + } + + const serializedName = serializeTypeName(context, node.exprName, /*isTypeOf*/ true); + if (serializedName) { + return setTextRange(context, serializedName, node.exprName); + } + } + + function tryVisitTypeReference(node: TypeReferenceNode): TypeNode | undefined { + if (canReuseTypeNode(context, node)) { + const { introducesError, node: newName } = trackExistingEntityName(node.typeName, context); + const typeArguments = visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode); + + if (!introducesError) { + const updated = factory.updateTypeReferenceNode( + node, + newName, + typeArguments, + ); + return setTextRange(context, updated, node); + } + else { + const serializedName = serializeTypeName(context, node.typeName, /*isTypeOf*/ false, typeArguments); + if (serializedName) { + return setTextRange(context, serializedName, node.typeName); + } + } + } + } + + function visitExistingNodeTreeSymbolsWorker(node: Node): Node | undefined { + if (isJSDocTypeExpression(node)) { + // Unwrap JSDocTypeExpressions + return visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode); + } + // We don't _actually_ support jsdoc namepath types, emit `any` instead + if (isJSDocAllType(node) || node.kind === SyntaxKind.JSDocNamepathType) { + return factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + } + if (isJSDocUnknownType(node)) { + return factory.createKeywordTypeNode(SyntaxKind.UnknownKeyword); + } + if (isJSDocNullableType(node)) { + return factory.createUnionTypeNode([visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)!, factory.createLiteralTypeNode(factory.createNull())]); + } + if (isJSDocOptionalType(node)) { + return factory.createUnionTypeNode([visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)!, factory.createKeywordTypeNode(SyntaxKind.UndefinedKeyword)]); + } + if (isJSDocNonNullableType(node)) { + return visitNode(node.type, visitExistingNodeTreeSymbols); + } + if (isJSDocVariadicType(node)) { + return factory.createArrayTypeNode(visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)!); + } + if (isJSDocTypeLiteral(node)) { + return factory.createTypeLiteralNode(map(node.jsDocPropertyTags, t => { + const name = visitNode(isIdentifier(t.name) ? t.name : t.name.right, visitExistingNodeTreeSymbols, isIdentifier)!; + const typeViaParent = getTypeOfPropertyOfType(getTypeFromTypeNode(context, node), name.escapedText); + const overrideTypeNode = typeViaParent && t.typeExpression && getTypeFromTypeNode(context, t.typeExpression.type) !== typeViaParent ? typeToTypeNodeHelper(typeViaParent, context) : undefined; + + return factory.createPropertySignature( + /*modifiers*/ undefined, + name, + t.isBracketed || t.typeExpression && isJSDocOptionalType(t.typeExpression.type) ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + overrideTypeNode || (t.typeExpression && visitNode(t.typeExpression.type, visitExistingNodeTreeSymbols, isTypeNode)) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), + ); + })); + } + if (isTypeReferenceNode(node) && isIdentifier(node.typeName) && node.typeName.escapedText === "") { + return setOriginalNode(factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), node); + } + if ((isExpressionWithTypeArguments(node) || isTypeReferenceNode(node)) && isJSDocIndexSignature(node)) { + return factory.createTypeLiteralNode([factory.createIndexSignature( + /*modifiers*/ undefined, + [factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + "x", + /*questionToken*/ undefined, + visitNode(node.typeArguments![0], visitExistingNodeTreeSymbols, isTypeNode), + )], + visitNode(node.typeArguments![1], visitExistingNodeTreeSymbols, isTypeNode), + )]); + } + if (isJSDocFunctionType(node)) { + if (isJSDocConstructSignature(node)) { + let newTypeNode: TypeNode | undefined; + return factory.createConstructorTypeNode( + /*modifiers*/ undefined, + visitNodes(node.typeParameters, visitExistingNodeTreeSymbols, isTypeParameterDeclaration), + mapDefined(node.parameters, (p, i) => + p.name && isIdentifier(p.name) && p.name.escapedText === "new" ? (newTypeNode = p.type, undefined) : factory.createParameterDeclaration( + /*modifiers*/ undefined, + getEffectiveDotDotDotForParameter(p), + setTextRange(context, factory.createIdentifier(getNameForJSDocFunctionParameter(p, i)), p), + factory.cloneNode(p.questionToken), + visitNode(p.type, visitExistingNodeTreeSymbols, isTypeNode), + /*initializer*/ undefined, + )), + visitNode(newTypeNode || node.type, visitExistingNodeTreeSymbols, isTypeNode) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), + ); + } + else { + return factory.createFunctionTypeNode( + visitNodes(node.typeParameters, visitExistingNodeTreeSymbols, isTypeParameterDeclaration), + map(node.parameters, (p, i) => + factory.createParameterDeclaration( + /*modifiers*/ undefined, + getEffectiveDotDotDotForParameter(p), + setTextRange(context, factory.createIdentifier(getNameForJSDocFunctionParameter(p, i)), p), + factory.cloneNode(p.questionToken), + visitNode(p.type, visitExistingNodeTreeSymbols, isTypeNode), + /*initializer*/ undefined, + )), + visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode) || factory.createKeywordTypeNode(SyntaxKind.AnyKeyword), + ); + } + } + if (isThisTypeNode(node)) { + if (canReuseTypeNode(context, node)) { + return node; + } + hadError = true; + return node; + } + if (isTypeParameterDeclaration(node)) { + return factory.updateTypeParameterDeclaration( + node, + visitNodes(node.modifiers, visitExistingNodeTreeSymbols, isModifier), + setTextRange(context, typeParameterToName(getDeclaredTypeOfSymbol(getSymbolOfDeclaration(node)), context), node), + visitNode(node.constraint, visitExistingNodeTreeSymbols, isTypeNode), + visitNode(node.default, visitExistingNodeTreeSymbols, isTypeNode), + ); + } + + if (isIndexedAccessTypeNode(node)) { + const result = tryVisitIndexedAccess(node); + if (!result) { + hadError = true; + return node; + } + return result; + } + + if (isTypeReferenceNode(node)) { + const result = tryVisitTypeReference(node); + if (result) { + return result; + } + hadError = true; + return node; + } + if (isLiteralImportTypeNode(node)) { + const nodeSymbol = getNodeLinks(node).resolvedSymbol; + if ( + isInJSDoc(node) && + nodeSymbol && + ( + // The import type resolved using jsdoc fallback logic + (!node.isTypeOf && !(nodeSymbol.flags & SymbolFlags.Type)) || + // The import type had type arguments autofilled by js fallback logic + !(length(node.typeArguments) >= getMinTypeArgumentCount(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(nodeSymbol))) + ) + ) { + return setTextRange(context, typeToTypeNodeHelper(getTypeFromTypeNode(context, node), context), node); + } + return factory.updateImportTypeNode( + node, + factory.updateLiteralTypeNode(node.argument, rewriteModuleSpecifier(node, node.argument.literal)), + visitNode(node.attributes, visitExistingNodeTreeSymbols, isImportAttributes), + visitNode(node.qualifier, visitExistingNodeTreeSymbols, isEntityName), + visitNodes(node.typeArguments, visitExistingNodeTreeSymbols, isTypeNode), + node.isTypeOf, + ); + } + if (isNamedDeclaration(node) && node.name.kind === SyntaxKind.ComputedPropertyName && !isLateBindableName(node.name)) { + if (!(context.flags & NodeBuilderFlags.AllowUnresolvedNames && hasDynamicName(node) && isEntityNameExpression(node.name.expression) && checkComputedPropertyName(node.name).flags & TypeFlags.Any)) { + return undefined; + } + } + if ( + (isFunctionLike(node) && !node.type) + || (isPropertyDeclaration(node) && !node.type && !node.initializer) + || (isPropertySignature(node) && !node.type && !node.initializer) + || (isParameter(node) && !node.type && !node.initializer) + ) { + let visited = visitEachChild(node, visitExistingNodeTreeSymbols); + if (visited === node) { + visited = setTextRange(context, factory.cloneNode(node), node); + } + (visited as Mutable).type = factory.createKeywordTypeNode(SyntaxKind.AnyKeyword); + if (isParameter(node)) { + (visited as Mutable).modifiers = undefined; + } + return visited; + } + if (isTypeQueryNode(node)) { + const result = tryVisitTypeQuery(node); + if (!result) { + hadError = true; + return node; + } + return result; + } + if (isComputedPropertyName(node) && isEntityNameExpression(node.expression)) { + const { node: result, introducesError } = trackExistingEntityName(node.expression, context); + if (!introducesError) { + return factory.updateComputedPropertyName(node, result); + } + else { + const type = getWidenedType(getRegularTypeOfExpression(node.expression)); + const computedPropertyNameType = typeToTypeNodeHelper(type, context); + let literal; + if (isLiteralTypeNode(computedPropertyNameType)) { + literal = computedPropertyNameType.literal; + } + else { + const evaluated = evaluateEntityNameExpression(node.expression); + const literalNode = typeof evaluated.value === "string" ? factory.createStringLiteral(evaluated.value, /*isSingleQuote*/ undefined) : + typeof evaluated.value === "number" ? factory.createNumericLiteral(evaluated.value, /*numericLiteralFlags*/ 0) : + undefined; + if (!literalNode) { + if (isImportTypeNode(computedPropertyNameType)) { + trackComputedName(node.expression, context.enclosingDeclaration, context); + } + return node; + } + literal = literalNode; + } + if (literal.kind === SyntaxKind.StringLiteral && isIdentifierText(literal.text, getEmitScriptTarget(compilerOptions))) { + return factory.createIdentifier(literal.text); + } + if (literal.kind === SyntaxKind.NumericLiteral && !literal.text.startsWith("-")) { + return literal; + } + return factory.updateComputedPropertyName(node, literal); + } + } + if (isTypePredicateNode(node)) { + let parameterName; + if (isIdentifier(node.parameterName)) { + const { node: result, introducesError } = trackExistingEntityName(node.parameterName, context); + // Should not usually happen the only case is when a type predicate comes from a JSDoc type annotation with it's own parameter symbol definition. + // /** @type {(v: unknown) => v is undefined} */ + // const isUndef = v => v === undefined; + hadError = hadError || introducesError; + parameterName = result; + } + else { + parameterName = factory.cloneNode(node.parameterName); + } + return factory.updateTypePredicateNode(node, factory.cloneNode(node.assertsModifier), parameterName, visitNode(node.type, visitExistingNodeTreeSymbols, isTypeNode)); + } + + if (isTupleTypeNode(node) || isTypeLiteralNode(node) || isMappedTypeNode(node)) { + const visited = visitEachChild(node, visitExistingNodeTreeSymbols); + const clone = setTextRange(context, visited === node ? factory.cloneNode(node) : visited, node); + const flags = getEmitFlags(clone); + setEmitFlags(clone, flags | (context.flags & NodeBuilderFlags.MultilineObjectLiterals && isTypeLiteralNode(node) ? 0 : EmitFlags.SingleLine)); + return clone; + } + if (isStringLiteral(node) && !!(context.flags & NodeBuilderFlags.UseSingleQuotesForStringLiteralType) && !node.singleQuote) { + const clone = factory.cloneNode(node); + (clone as Mutable).singleQuote = true; + return clone; + } + if (isConditionalTypeNode(node)) { + const checkType = visitNode(node.checkType, visitExistingNodeTreeSymbols, isTypeNode)!; + + const disposeScope = onEnterNewScope(node); + const extendType = visitNode(node.extendsType, visitExistingNodeTreeSymbols, isTypeNode)!; + const trueType = visitNode(node.trueType, visitExistingNodeTreeSymbols, isTypeNode)!; + disposeScope(); + const falseType = visitNode(node.falseType, visitExistingNodeTreeSymbols, isTypeNode)!; + return factory.updateConditionalTypeNode( + node, + checkType, + extendType, + trueType, + falseType, + ); + } + + if (isTypeOperatorNode(node)) { + if (node.operator === SyntaxKind.UniqueKeyword && node.type.kind === SyntaxKind.SymbolKeyword) { + if (!canReuseTypeNode(context, node)) { + hadError = true; + return node; + } + } + else if (node.operator === SyntaxKind.KeyOfKeyword) { + const result = tryVisitKeyOf(node); + if (!result) { + hadError = true; + return node; + } + return result; + } + } + + return visitEachChild(node, visitExistingNodeTreeSymbols); + + function visitEachChild(node: T, visitor: Visitor): T; + function visitEachChild(node: T | undefined, visitor: Visitor): T | undefined; + function visitEachChild(node: T | undefined, visitor: Visitor): T | undefined { + const nonlocalNode = !context.enclosingFile || context.enclosingFile !== getSourceFileOfNode(node); + return visitEachChildWorker(node, visitor, /*context*/ undefined, nonlocalNode ? visitNodesWithoutCopyingPositions : undefined); + } + + function visitNodesWithoutCopyingPositions( + nodes: NodeArray | undefined, + visitor: Visitor, + test?: (node: Node) => boolean, + start?: number, + count?: number, + ): NodeArray | undefined { + let result = visitNodes(nodes, visitor, test, start, count); + if (result) { + if (result.pos !== -1 || result.end !== -1) { + if (result === nodes) { + result = factory.createNodeArray(nodes, nodes.hasTrailingComma); + } + setTextRangePosEnd(result, -1, -1); + } + } + return result; + } + + function getEffectiveDotDotDotForParameter(p: ParameterDeclaration) { + return p.dotDotDotToken || (p.type && isJSDocVariadicType(p.type) ? factory.createToken(SyntaxKind.DotDotDotToken) : undefined); + } + + /** Note that `new:T` parameters are not handled, but should be before calling this function. */ + function getNameForJSDocFunctionParameter(p: ParameterDeclaration, index: number) { + return p.name && isIdentifier(p.name) && p.name.escapedText === "this" ? "this" + : getEffectiveDotDotDotForParameter(p) ? `args` + : `arg${index}`; + } + + function rewriteModuleSpecifier(parent: ImportTypeNode, lit: StringLiteral) { + if (context.bundled || context.enclosingFile !== getSourceFileOfNode(lit)) { + let name = lit.text; + const nodeSymbol = getNodeLinks(node).resolvedSymbol; + const meaning = parent.isTypeOf ? SymbolFlags.Value : SymbolFlags.Type; + const parentSymbol = nodeSymbol + && isSymbolAccessible(nodeSymbol, context.enclosingDeclaration, meaning, /*shouldComputeAliasesToMakeVisible*/ false).accessibility === SymbolAccessibility.Accessible + && lookupSymbolChain(nodeSymbol, context, meaning, /*yieldModuleSymbol*/ true)[0]; + if (parentSymbol && isExternalModuleSymbol(parentSymbol)) { + name = getSpecifierForModuleSymbol(parentSymbol, context); + } + else { + const targetFile = getExternalModuleFileFromDeclaration(parent); + if (targetFile) { + name = getSpecifierForModuleSymbol(targetFile.symbol, context); + } + } + if (name.includes("/node_modules/")) { + context.encounteredError = true; + if (context.tracker.reportLikelyUnsafeImportRequiredError) { + context.tracker.reportLikelyUnsafeImportRequiredError(name); + } + } + if (name !== lit.text) { + return setOriginalNode(factory.createStringLiteral(name), lit); + } + } + return visitNode(lit, visitExistingNodeTreeSymbols, isStringLiteral)!; + } + } + } + + function symbolTableToDeclarationStatements(symbolTable: SymbolTable, context: NodeBuilderContext): Statement[] { + const serializePropertySymbolForClass = makeSerializePropertySymbol(factory.createPropertyDeclaration, SyntaxKind.MethodDeclaration, /*useAccessors*/ true); + const serializePropertySymbolForInterfaceWorker = makeSerializePropertySymbol((mods, name, question, type) => factory.createPropertySignature(mods, name, question, type), SyntaxKind.MethodSignature, /*useAccessors*/ false); + + // TODO: Use `setOriginalNode` on original declaration names where possible so these declarations see some kind of + // declaration mapping + + // We save the enclosing declaration off here so it's not adjusted by well-meaning declaration + // emit codepaths which want to apply more specific contexts (so we can still refer to the root real declaration + // we're trying to emit from later on) + const enclosingDeclaration = context.enclosingDeclaration!; + let results: Statement[] = []; + const visitedSymbols = new Set(); + const deferredPrivatesStack: Map[] = []; + const oldcontext = context; + context = { + ...oldcontext, + usedSymbolNames: new Set(oldcontext.usedSymbolNames), + remappedSymbolNames: new Map(), + remappedSymbolReferences: new Map(oldcontext.remappedSymbolReferences?.entries()), + tracker: undefined!, + }; + const tracker: SymbolTracker = { + ...oldcontext.tracker.inner, + trackSymbol: (sym, decl, meaning) => { + if (context.remappedSymbolNames?.has(getSymbolId(sym))) return false; // If the context has a remapped name for the symbol, it *should* mean it's been made visible + const accessibleResult = isSymbolAccessible(sym, decl, meaning, /*shouldComputeAliasesToMakeVisible*/ false); + if (accessibleResult.accessibility === SymbolAccessibility.Accessible) { + // Lookup the root symbol of the chain of refs we'll use to access it and serialize it + const chain = lookupSymbolChainWorker(sym, context, meaning); + if (!(sym.flags & SymbolFlags.Property)) { + // Only include referenced privates in the same file. Weird JS aliases may expose privates + // from other files - assume JS transforms will make those available via expected means + const root = chain[0]; + const contextFile = getSourceFileOfNode(oldcontext.enclosingDeclaration); + if (some(root.declarations, d => getSourceFileOfNode(d) === contextFile)) { + includePrivateSymbol(root); + } + } + } + else if (oldcontext.tracker.inner?.trackSymbol) { + return oldcontext.tracker.inner.trackSymbol(sym, decl, meaning); + } + return false; + }, + }; + context.tracker = new SymbolTrackerImpl(context, tracker, oldcontext.tracker.moduleResolverHost); + forEachEntry(symbolTable, (symbol, name) => { + const baseName = unescapeLeadingUnderscores(name); + void getInternalSymbolName(symbol, baseName); // Called to cache values into `usedSymbolNames` and `remappedSymbolNames` + }); + let addingDeclare = !context.bundled; + const exportEquals = symbolTable.get(InternalSymbolName.ExportEquals); + if (exportEquals && symbolTable.size > 1 && exportEquals.flags & (SymbolFlags.Alias | SymbolFlags.Module)) { + symbolTable = createSymbolTable(); + // Remove extraneous elements from root symbol table (they'll be mixed back in when the target of the `export=` is looked up) + symbolTable.set(InternalSymbolName.ExportEquals, exportEquals); + } + + visitSymbolTable(symbolTable); + return mergeRedundantStatements(results); + + function isIdentifierAndNotUndefined(node: Node | undefined): node is Identifier { + return !!node && node.kind === SyntaxKind.Identifier; + } + + function getNamesOfDeclaration(statement: Statement): Identifier[] { + if (isVariableStatement(statement)) { + return filter(map(statement.declarationList.declarations, getNameOfDeclaration), isIdentifierAndNotUndefined); + } + return filter([getNameOfDeclaration(statement as DeclarationStatement)], isIdentifierAndNotUndefined); + } + + function flattenExportAssignedNamespace(statements: Statement[]) { + const exportAssignment = find(statements, isExportAssignment); + const nsIndex = findIndex(statements, isModuleDeclaration); + let ns = nsIndex !== -1 ? statements[nsIndex] as ModuleDeclaration : undefined; + if ( + ns && exportAssignment && exportAssignment.isExportEquals && + isIdentifier(exportAssignment.expression) && isIdentifier(ns.name) && idText(ns.name) === idText(exportAssignment.expression) && + ns.body && isModuleBlock(ns.body) + ) { + // Pass 0: Correct situations where a module has both an `export = ns` and multiple top-level exports by stripping the export modifiers from + // the top-level exports and exporting them in the targeted ns, as can occur when a js file has both typedefs and `module.export` assignments + const excessExports = filter(statements, s => !!(getEffectiveModifierFlags(s) & ModifierFlags.Export)); + const name = ns.name; + let body = ns.body; + if (length(excessExports)) { + ns = factory.updateModuleDeclaration( + ns, + ns.modifiers, + ns.name, + body = factory.updateModuleBlock( + body, + factory.createNodeArray([ + ...ns.body.statements, + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(map(flatMap(excessExports, e => getNamesOfDeclaration(e)), id => factory.createExportSpecifier(/*isTypeOnly*/ false, /*propertyName*/ undefined, id))), + /*moduleSpecifier*/ undefined, + ), + ]), + ), + ); + statements = [...statements.slice(0, nsIndex), ns, ...statements.slice(nsIndex + 1)]; + } + + // Pass 1: Flatten `export namespace _exports {} export = _exports;` so long as the `export=` only points at a single namespace declaration + if (!find(statements, s => s !== ns && nodeHasName(s, name))) { + results = []; + // If the namespace contains no export assignments or declarations, and no declarations flagged with `export`, then _everything_ is exported - + // to respect this as the top level, we need to add an `export` modifier to everything + const mixinExportFlag = !some(body.statements, s => hasSyntacticModifier(s, ModifierFlags.Export) || isExportAssignment(s) || isExportDeclaration(s)); + forEach(body.statements, s => { + addResult(s, mixinExportFlag ? ModifierFlags.Export : ModifierFlags.None); // Recalculates the ambient (and export, if applicable from above) flag + }); + statements = [...filter(statements, s => s !== ns && s !== exportAssignment), ...results]; + } + } + return statements; + } + + function mergeExportDeclarations(statements: Statement[]) { + // Pass 2: Combine all `export {}` declarations + const exports = filter(statements, d => isExportDeclaration(d) && !d.moduleSpecifier && !!d.exportClause && isNamedExports(d.exportClause)) as ExportDeclaration[]; + if (length(exports) > 1) { + const nonExports = filter(statements, d => !isExportDeclaration(d) || !!d.moduleSpecifier || !d.exportClause); + statements = [ + ...nonExports, + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(flatMap(exports, e => cast(e.exportClause, isNamedExports).elements)), + /*moduleSpecifier*/ undefined, + ), + ]; + } + // Pass 2b: Also combine all `export {} from "..."` declarations as needed + const reexports = filter(statements, d => isExportDeclaration(d) && !!d.moduleSpecifier && !!d.exportClause && isNamedExports(d.exportClause)) as ExportDeclaration[]; + if (length(reexports) > 1) { + const groups = group(reexports, decl => isStringLiteral(decl.moduleSpecifier!) ? ">" + decl.moduleSpecifier.text : ">"); + if (groups.length !== reexports.length) { + for (const group of groups) { + if (group.length > 1) { + // remove group members from statements and then merge group members and add back to statements + statements = [ + ...filter(statements, s => !group.includes(s as ExportDeclaration)), + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(flatMap(group, e => cast(e.exportClause, isNamedExports).elements)), + group[0].moduleSpecifier, + ), + ]; + } + } + } + } + return statements; + } + + function inlineExportModifiers(statements: Statement[]) { + // Pass 3: Move all `export {}`'s to `export` modifiers where possible + const index = findIndex(statements, d => isExportDeclaration(d) && !d.moduleSpecifier && !d.attributes && !!d.exportClause && isNamedExports(d.exportClause)); + if (index >= 0) { + const exportDecl = statements[index] as ExportDeclaration & { readonly exportClause: NamedExports; }; + const replacements = mapDefined(exportDecl.exportClause.elements, e => { + if (!e.propertyName && e.name.kind !== SyntaxKind.StringLiteral) { + // export {name} - look thru `statements` for `name`, and if all results can take an `export` modifier, do so and filter it + const name = e.name; + const indices = indicesOf(statements); + const associatedIndices = filter(indices, i => nodeHasName(statements[i], name)); + if (length(associatedIndices) && every(associatedIndices, i => canHaveExportModifier(statements[i]))) { + for (const index of associatedIndices) { + statements[index] = addExportModifier(statements[index] as Extract); + } + return undefined; + } + } + return e; + }); + if (!length(replacements)) { + // all clauses removed, remove the export declaration + orderedRemoveItemAt(statements, index); + } + else { + // some items filtered, others not - update the export declaration + statements[index] = factory.updateExportDeclaration( + exportDecl, + exportDecl.modifiers, + exportDecl.isTypeOnly, + factory.updateNamedExports( + exportDecl.exportClause, + replacements, + ), + exportDecl.moduleSpecifier, + exportDecl.attributes, + ); + } + } + return statements; + } + + function mergeRedundantStatements(statements: Statement[]) { + statements = flattenExportAssignedNamespace(statements); + statements = mergeExportDeclarations(statements); + statements = inlineExportModifiers(statements); + + // Not a cleanup, but as a final step: If there is a mix of `export` and non-`export` declarations, but no `export =` or `export {}` add a `export {};` so + // declaration privacy is respected. + if ( + enclosingDeclaration && + ((isSourceFile(enclosingDeclaration) && isExternalOrCommonJsModule(enclosingDeclaration)) || isModuleDeclaration(enclosingDeclaration)) && + (!some(statements, isExternalModuleIndicator) || (!hasScopeMarker(statements) && some(statements, needsScopeMarker))) + ) { + statements.push(createEmptyExports(factory)); + } + return statements; + } + + function addExportModifier(node: Extract) { + const flags = (getEffectiveModifierFlags(node) | ModifierFlags.Export) & ~ModifierFlags.Ambient; + return factory.replaceModifiers(node, flags); + } + + function removeExportModifier(node: Extract) { + const flags = getEffectiveModifierFlags(node) & ~ModifierFlags.Export; + return factory.replaceModifiers(node, flags); + } + + function visitSymbolTable(symbolTable: SymbolTable, suppressNewPrivateContext?: boolean, propertyAsAlias?: boolean) { + if (!suppressNewPrivateContext) { + deferredPrivatesStack.push(new Map()); + } + symbolTable.forEach((symbol: Symbol) => { + serializeSymbol(symbol, /*isPrivate*/ false, !!propertyAsAlias); + }); + if (!suppressNewPrivateContext) { + // deferredPrivates will be filled up by visiting the symbol table + // And will continue to iterate as elements are added while visited `deferredPrivates` + // (As that's how a map iterator is defined to work) + deferredPrivatesStack[deferredPrivatesStack.length - 1].forEach((symbol: Symbol) => { + serializeSymbol(symbol, /*isPrivate*/ true, !!propertyAsAlias); + }); + deferredPrivatesStack.pop(); + } + } + + function serializeSymbol(symbol: Symbol, isPrivate: boolean, propertyAsAlias: boolean): void { + void getPropertiesOfType(getTypeOfSymbol(symbol)); // resolve symbol's type and properties, which should trigger any required merges + // cache visited list based on merged symbol, since we want to use the unmerged top-level symbol, but + // still skip reserializing it if we encounter the merged product later on + const visitedSym = getMergedSymbol(symbol); + if (visitedSymbols.has(getSymbolId(visitedSym))) { + return; // Already printed + } + visitedSymbols.add(getSymbolId(visitedSym)); + // Only actually serialize symbols within the correct enclosing declaration, otherwise do nothing with the out-of-context symbol + const skipMembershipCheck = !isPrivate; // We only call this on exported symbols when we know they're in the correct scope + if (skipMembershipCheck || (!!length(symbol.declarations) && some(symbol.declarations, d => !!findAncestor(d, n => n === enclosingDeclaration)))) { + const scopeCleanup = cloneNodeBuilderContext(context); + serializeSymbolWorker(symbol, isPrivate, propertyAsAlias); + scopeCleanup(); + } + } + + // Synthesize declarations for a symbol - might be an Interface, a Class, a Namespace, a Type, a Variable (const, let, or var), an Alias + // or a merge of some number of those. + // An interesting challenge is ensuring that when classes merge with namespaces and interfaces, is keeping + // each symbol in only one of the representations + // Also, synthesizing a default export of some kind + // If it's an alias: emit `export default ref` + // If it's a property: emit `export default _default` with a `_default` prop + // If it's a class/interface/function: emit a class/interface/function with a `default` modifier + // These forms can merge, eg (`export default 12; export default interface A {}`) + function serializeSymbolWorker(symbol: Symbol, isPrivate: boolean, propertyAsAlias: boolean, escapedSymbolName = symbol.escapedName): void { + const symbolName = unescapeLeadingUnderscores(escapedSymbolName); + const isDefault = escapedSymbolName === InternalSymbolName.Default; + if (isPrivate && !(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier) && isStringANonContextualKeyword(symbolName) && !isDefault) { + // Oh no. We cannot use this symbol's name as it's name... It's likely some jsdoc had an invalid name like `export` or `default` :( + context.encounteredError = true; + // TODO: Issue error via symbol tracker? + return; // If we need to emit a private with a keyword name, we're done for, since something else will try to refer to it by that name + } + let needsPostExportDefault = isDefault && !!( + symbol.flags & SymbolFlags.ExportDoesNotSupportDefaultModifier + || (symbol.flags & SymbolFlags.Function && length(getPropertiesOfType(getTypeOfSymbol(symbol)))) + ) && !(symbol.flags & SymbolFlags.Alias); // An alias symbol should preclude needing to make an alias ourselves + let needsExportDeclaration = !needsPostExportDefault && !isPrivate && isStringANonContextualKeyword(symbolName) && !isDefault; + // `serializeVariableOrProperty` will handle adding the export declaration if it is run (since `getInternalSymbolName` will create the name mapping), so we need to ensuer we unset `needsExportDeclaration` if it is + if (needsPostExportDefault || needsExportDeclaration) { + isPrivate = true; + } + const modifierFlags = (!isPrivate ? ModifierFlags.Export : 0) | (isDefault && !needsPostExportDefault ? ModifierFlags.Default : 0); + const isConstMergedWithNS = symbol.flags & SymbolFlags.Module && + symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.FunctionScopedVariable | SymbolFlags.Property) && + escapedSymbolName !== InternalSymbolName.ExportEquals; + const isConstMergedWithNSPrintableAsSignatureMerge = isConstMergedWithNS && isTypeRepresentableAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol); + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method) || isConstMergedWithNSPrintableAsSignatureMerge) { + serializeAsFunctionNamespaceMerge(getTypeOfSymbol(symbol), symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + if (symbol.flags & SymbolFlags.TypeAlias) { + serializeTypeAlias(symbol, symbolName, modifierFlags); + } + // Need to skip over export= symbols below - json source files get a single `Property` flagged + // symbol of name `export=` which needs to be handled like an alias. It's not great, but it is what it is. + if ( + symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.FunctionScopedVariable | SymbolFlags.Property | SymbolFlags.Accessor) + && escapedSymbolName !== InternalSymbolName.ExportEquals + && !(symbol.flags & SymbolFlags.Prototype) + && !(symbol.flags & SymbolFlags.Class) + && !(symbol.flags & SymbolFlags.Method) + && !isConstMergedWithNSPrintableAsSignatureMerge + ) { + if (propertyAsAlias) { + const createdExport = serializeMaybeAliasAssignment(symbol); + if (createdExport) { + needsExportDeclaration = false; + needsPostExportDefault = false; + } + } + else { + const type = getTypeOfSymbol(symbol); + const localName = getInternalSymbolName(symbol, symbolName); + if (type.symbol && type.symbol !== symbol && type.symbol.flags & SymbolFlags.Function && some(type.symbol.declarations, isFunctionExpressionOrArrowFunction) && (type.symbol.members?.size || type.symbol.exports?.size)) { + // assignment of a anonymous expando/class-like function, the func/ns/merge branch below won't trigger, + // and the assignment form has to reference the unreachable anonymous type so will error. + // Instead, serialize the type's symbol, but with the current symbol's name, rather than the anonymous one. + if (!context.remappedSymbolReferences) { + context.remappedSymbolReferences = new Map(); + } + context.remappedSymbolReferences.set(getSymbolId(type.symbol), symbol); // save name remapping as local name for target symbol + serializeSymbolWorker(type.symbol, isPrivate, propertyAsAlias, escapedSymbolName); + context.remappedSymbolReferences.delete(getSymbolId(type.symbol)); + } + else if (!(symbol.flags & SymbolFlags.Function) && isTypeRepresentableAsFunctionNamespaceMerge(type, symbol)) { + // If the type looks like a function declaration + ns could represent it, and it's type is sourced locally, rewrite it into a function declaration + ns + serializeAsFunctionNamespaceMerge(type, symbol, localName, modifierFlags); + } + else { + // A Class + Property merge is made for a `module.exports.Member = class {}`, and it doesn't serialize well as either a class _or_ a property symbol - in fact, _it behaves like an alias!_ + // `var` is `FunctionScopedVariable`, `const` and `let` are `BlockScopedVariable`, and `module.exports.thing =` is `Property` + const flags = !(symbol.flags & SymbolFlags.BlockScopedVariable) + ? symbol.parent?.valueDeclaration && isSourceFile(symbol.parent?.valueDeclaration) + ? NodeFlags.Const // exports are immutable in es6, which is what we emulate and check; so it's safe to mark all exports as `const` (there's no difference to consumers, but it allows unique symbol type declarations) + : undefined + : isConstantVariable(symbol) + ? NodeFlags.Const + : NodeFlags.Let; + const name = (needsPostExportDefault || !(symbol.flags & SymbolFlags.Property)) ? localName : getUnusedName(localName, symbol); + let textRange: Node | undefined = symbol.declarations && find(symbol.declarations, d => isVariableDeclaration(d)); + if (textRange && isVariableDeclarationList(textRange.parent) && textRange.parent.declarations.length === 1) { + textRange = textRange.parent.parent; + } + const propertyAccessRequire = symbol.declarations?.find(isPropertyAccessExpression); + if ( + propertyAccessRequire && isBinaryExpression(propertyAccessRequire.parent) && isIdentifier(propertyAccessRequire.parent.right) + && type.symbol?.valueDeclaration && isSourceFile(type.symbol.valueDeclaration) + ) { + const alias = localName === propertyAccessRequire.parent.right.escapedText ? undefined : propertyAccessRequire.parent.right; + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, alias, localName)]), + ), + ModifierFlags.None, + ); + context.tracker.trackSymbol(type.symbol, context.enclosingDeclaration, SymbolFlags.Value); + } + else { + const statement = setTextRange( + context, + factory.createVariableStatement( + /*modifiers*/ undefined, + factory.createVariableDeclarationList([ + factory.createVariableDeclaration(name, /*exclamationToken*/ undefined, serializeTypeForDeclaration(context, /*declaration*/ undefined, type, symbol)), + ], flags), + ), + textRange, + ); + addResult(statement, name !== localName ? modifierFlags & ~ModifierFlags.Export : modifierFlags); + if (name !== localName && !isPrivate) { + // We rename the variable declaration we generate for Property symbols since they may have a name which + // conflicts with a local declaration. For example, given input: + // ``` + // function g() {} + // module.exports.g = g + // ``` + // In such a situation, we have a local variable named `g`, and a separate exported variable named `g`. + // Naively, we would emit + // ``` + // function g() {} + // export const g: typeof g; + // ``` + // That's obviously incorrect - the `g` in the type annotation needs to refer to the local `g`, but + // the export declaration shadows it. + // To work around that, we instead write + // ``` + // function g() {} + // const g_1: typeof g; + // export { g_1 as g }; + // ``` + // To create an export named `g` that does _not_ shadow the local `g` + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, name, localName)]), + ), + ModifierFlags.None, + ); + needsExportDeclaration = false; + needsPostExportDefault = false; + } + } + } + } + } + if (symbol.flags & SymbolFlags.Enum) { + serializeEnum(symbol, symbolName, modifierFlags); + } + if (symbol.flags & SymbolFlags.Class) { + if ( + symbol.flags & SymbolFlags.Property + && symbol.valueDeclaration + && isBinaryExpression(symbol.valueDeclaration.parent) + && isClassExpression(symbol.valueDeclaration.parent.right) + ) { + // Looks like a `module.exports.Sub = class {}` - if we serialize `symbol` as a class, the result will have no members, + // since the classiness is actually from the target of the effective alias the symbol is. yes. A BlockScopedVariable|Class|Property + // _really_ acts like an Alias, and none of a BlockScopedVariable, Class, or Property. This is the travesty of JS binding today. + serializeAsAlias(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + else { + serializeAsClass(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + } + if ((symbol.flags & (SymbolFlags.ValueModule | SymbolFlags.NamespaceModule) && (!isConstMergedWithNS || isTypeOnlyNamespace(symbol))) || isConstMergedWithNSPrintableAsSignatureMerge) { + serializeModule(symbol, symbolName, modifierFlags); + } + // The class meaning serialization should handle serializing all interface members + if (symbol.flags & SymbolFlags.Interface && !(symbol.flags & SymbolFlags.Class)) { + serializeInterface(symbol, symbolName, modifierFlags); + } + if (symbol.flags & SymbolFlags.Alias) { + serializeAsAlias(symbol, getInternalSymbolName(symbol, symbolName), modifierFlags); + } + if (symbol.flags & SymbolFlags.Property && symbol.escapedName === InternalSymbolName.ExportEquals) { + serializeMaybeAliasAssignment(symbol); + } + if (symbol.flags & SymbolFlags.ExportStar) { + // synthesize export * from "moduleReference" + // Straightforward - only one thing to do - make an export declaration + if (symbol.declarations) { + for (const node of symbol.declarations) { + const resolvedModule = resolveExternalModuleName(node, (node as ExportDeclaration).moduleSpecifier!); + if (!resolvedModule) continue; + addResult(factory.createExportDeclaration(/*modifiers*/ undefined, /*isTypeOnly*/ (node as ExportDeclaration).isTypeOnly, /*exportClause*/ undefined, factory.createStringLiteral(getSpecifierForModuleSymbol(resolvedModule, context))), ModifierFlags.None); + } + } + } + if (needsPostExportDefault) { + addResult(factory.createExportAssignment(/*modifiers*/ undefined, /*isExportEquals*/ false, factory.createIdentifier(getInternalSymbolName(symbol, symbolName))), ModifierFlags.None); + } + else if (needsExportDeclaration) { + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, getInternalSymbolName(symbol, symbolName), symbolName)]), + ), + ModifierFlags.None, + ); + } + } + + function includePrivateSymbol(symbol: Symbol) { + if (some(symbol.declarations, isPartOfParameterDeclaration)) return; + Debug.assertIsDefined(deferredPrivatesStack[deferredPrivatesStack.length - 1]); + getUnusedName(unescapeLeadingUnderscores(symbol.escapedName), symbol); // Call to cache unique name for symbol + // Blanket moving (import) aliases into the root private context should work, since imports are not valid within namespaces + // (so they must have been in the root to begin with if they were real imports) cjs `require` aliases (an upcoming feature) + // will throw a wrench in this, since those may have been nested, but we'll need to synthesize them in the outer scope + // anyway, as that's the only place the import they translate to is valid. In such a case, we might need to use a unique name + // for the moved import; which hopefully the above `getUnusedName` call should produce. + const isExternalImportAlias = !!(symbol.flags & SymbolFlags.Alias) && !some(symbol.declarations, d => + !!findAncestor(d, isExportDeclaration) || + isNamespaceExport(d) || + (isImportEqualsDeclaration(d) && !isExternalModuleReference(d.moduleReference))); + deferredPrivatesStack[isExternalImportAlias ? 0 : (deferredPrivatesStack.length - 1)].set(getSymbolId(symbol), symbol); + } + + function isExportingScope(enclosingDeclaration: Node) { + return ((isSourceFile(enclosingDeclaration) && (isExternalOrCommonJsModule(enclosingDeclaration) || isJsonSourceFile(enclosingDeclaration))) || + (isAmbientModule(enclosingDeclaration) && !isGlobalScopeAugmentation(enclosingDeclaration))); + } + + // Prepends a `declare` and/or `export` modifier if the context requires it, and then adds `node` to `result` and returns `node` + function addResult(node: Statement, additionalModifierFlags: ModifierFlags) { + if (canHaveModifiers(node)) { + let newModifierFlags: ModifierFlags = ModifierFlags.None; + const enclosingDeclaration = context.enclosingDeclaration && + (isJSDocTypeAlias(context.enclosingDeclaration) ? getSourceFileOfNode(context.enclosingDeclaration) : context.enclosingDeclaration); + if ( + additionalModifierFlags & ModifierFlags.Export && + enclosingDeclaration && (isExportingScope(enclosingDeclaration) || isModuleDeclaration(enclosingDeclaration)) && + canHaveExportModifier(node) + ) { + // Classes, namespaces, variables, functions, interfaces, and types should all be `export`ed in a module context if not private + newModifierFlags |= ModifierFlags.Export; + } + if ( + addingDeclare && !(newModifierFlags & ModifierFlags.Export) && + (!enclosingDeclaration || !(enclosingDeclaration.flags & NodeFlags.Ambient)) && + (isEnumDeclaration(node) || isVariableStatement(node) || isFunctionDeclaration(node) || isClassDeclaration(node) || isModuleDeclaration(node)) + ) { + // Classes, namespaces, variables, enums, and functions all need `declare` modifiers to be valid in a declaration file top-level scope + newModifierFlags |= ModifierFlags.Ambient; + } + if ((additionalModifierFlags & ModifierFlags.Default) && (isClassDeclaration(node) || isInterfaceDeclaration(node) || isFunctionDeclaration(node))) { + newModifierFlags |= ModifierFlags.Default; + } + if (newModifierFlags) { + node = factory.replaceModifiers(node, newModifierFlags | getEffectiveModifierFlags(node)); + } + } + results.push(node); + } + + function serializeTypeAlias(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + const aliasType = getDeclaredTypeOfTypeAlias(symbol); + const typeParams = getSymbolLinks(symbol).typeParameters; + const typeParamDecls = map(typeParams, p => typeParameterToDeclaration(p, context)); + const jsdocAliasDecl = symbol.declarations?.find(isJSDocTypeAlias); + const commentText = getTextOfJSDocComment(jsdocAliasDecl ? jsdocAliasDecl.comment || jsdocAliasDecl.parent.comment : undefined); + const oldFlags = context.flags; + context.flags |= NodeBuilderFlags.InTypeAlias; + const oldEnclosingDecl = context.enclosingDeclaration; + context.enclosingDeclaration = jsdocAliasDecl; + const typeNode = jsdocAliasDecl && jsdocAliasDecl.typeExpression + && isJSDocTypeExpression(jsdocAliasDecl.typeExpression) + && tryReuseExistingNonParameterTypeNode(context, jsdocAliasDecl.typeExpression.type, aliasType, /*host*/ undefined) + || typeToTypeNodeHelper(aliasType, context); + addResult( + setSyntheticLeadingComments( + factory.createTypeAliasDeclaration(/*modifiers*/ undefined, getInternalSymbolName(symbol, symbolName), typeParamDecls, typeNode), + !commentText ? [] : [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }], + ), + modifierFlags, + ); + context.flags = oldFlags; + context.enclosingDeclaration = oldEnclosingDecl; + } + + function serializeInterface(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + const interfaceType = getDeclaredTypeOfClassOrInterface(symbol); + const localParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + const typeParamDecls = map(localParams, p => typeParameterToDeclaration(p, context)); + const baseTypes = getBaseTypes(interfaceType); + const baseType = length(baseTypes) ? getIntersectionType(baseTypes) : undefined; + const members = flatMap(getPropertiesOfType(interfaceType), p => serializePropertySymbolForInterface(p, baseType)); + const callSignatures = serializeSignatures(SignatureKind.Call, interfaceType, baseType, SyntaxKind.CallSignature) as CallSignatureDeclaration[]; + const constructSignatures = serializeSignatures(SignatureKind.Construct, interfaceType, baseType, SyntaxKind.ConstructSignature) as ConstructSignatureDeclaration[]; + const indexSignatures = serializeIndexSignatures(interfaceType, baseType); + + const heritageClauses = !length(baseTypes) ? undefined : [factory.createHeritageClause(SyntaxKind.ExtendsKeyword, mapDefined(baseTypes, b => trySerializeAsTypeReference(b, SymbolFlags.Value)))]; + addResult( + factory.createInterfaceDeclaration( + /*modifiers*/ undefined, + getInternalSymbolName(symbol, symbolName), + typeParamDecls, + heritageClauses, + [...indexSignatures, ...constructSignatures, ...callSignatures, ...members], + ), + modifierFlags, + ); + } + + function getNamespaceMembersForSerialization(symbol: Symbol) { + let exports = arrayFrom(getExportsOfSymbol(symbol).values()); + const merged = getMergedSymbol(symbol); + if (merged !== symbol) { + const membersSet = new Set(exports); + for (const exported of getExportsOfSymbol(merged).values()) { + if (!(getSymbolFlags(resolveSymbol(exported)) & SymbolFlags.Value)) { + membersSet.add(exported); + } + } + exports = arrayFrom(membersSet); + } + return filter(exports, m => isNamespaceMember(m) && isIdentifierText(m.escapedName as string, ScriptTarget.ESNext)); + } + + function isTypeOnlyNamespace(symbol: Symbol) { + return every(getNamespaceMembersForSerialization(symbol), m => !(getSymbolFlags(resolveSymbol(m)) & SymbolFlags.Value)); + } + + function serializeModule(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + const members = getNamespaceMembersForSerialization(symbol); + // Split NS members up by declaration - members whose parent symbol is the ns symbol vs those whose is not (but were added in later via merging) + const locationMap = arrayToMultiMap(members, m => m.parent && m.parent === symbol ? "real" : "merged"); + const realMembers = locationMap.get("real") || emptyArray; + const mergedMembers = locationMap.get("merged") || emptyArray; + // TODO: `suppressNewPrivateContext` is questionable -we need to simply be emitting privates in whatever scope they were declared in, rather + // than whatever scope we traverse to them in. That's a bit of a complex rewrite, since we're not _actually_ tracking privates at all in advance, + // so we don't even have placeholders to fill in. + if (length(realMembers)) { + const localName = getInternalSymbolName(symbol, symbolName); + serializeAsNamespaceDeclaration(realMembers, localName, modifierFlags, !!(symbol.flags & (SymbolFlags.Function | SymbolFlags.Assignment))); + } + if (length(mergedMembers)) { + const containingFile = getSourceFileOfNode(context.enclosingDeclaration); + const localName = getInternalSymbolName(symbol, symbolName); + const nsBody = factory.createModuleBlock([factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports(mapDefined(filter(mergedMembers, n => n.escapedName !== InternalSymbolName.ExportEquals), s => { + const name = unescapeLeadingUnderscores(s.escapedName); + const localName = getInternalSymbolName(s, name); + const aliasDecl = s.declarations && getDeclarationOfAliasSymbol(s); + if (containingFile && (aliasDecl ? containingFile !== getSourceFileOfNode(aliasDecl) : !some(s.declarations, d => getSourceFileOfNode(d) === containingFile))) { + context.tracker?.reportNonlocalAugmentation?.(containingFile, symbol, s); + return undefined; + } + const target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true); + includePrivateSymbol(target || s); + const targetName = target ? getInternalSymbolName(target, unescapeLeadingUnderscores(target.escapedName)) : localName; + return factory.createExportSpecifier(/*isTypeOnly*/ false, name === targetName ? undefined : targetName, name); + })), + )]); + addResult( + factory.createModuleDeclaration( + /*modifiers*/ undefined, + factory.createIdentifier(localName), + nsBody, + NodeFlags.Namespace, + ), + ModifierFlags.None, + ); + } + } + + function serializeEnum(symbol: Symbol, symbolName: string, modifierFlags: ModifierFlags) { + addResult( + factory.createEnumDeclaration( + factory.createModifiersFromModifierFlags(isConstEnumSymbol(symbol) ? ModifierFlags.Const : 0), + getInternalSymbolName(symbol, symbolName), + map(filter(getPropertiesOfType(getTypeOfSymbol(symbol)), p => !!(p.flags & SymbolFlags.EnumMember)), p => { + // TODO: Handle computed names + // I hate that to get the initialized value we need to walk back to the declarations here; but there's no + // other way to get the possible const value of an enum member that I'm aware of, as the value is cached + // _on the declaration_, not on the declaration's symbol... + const initializedValue = p.declarations && p.declarations[0] && isEnumMember(p.declarations[0]) ? getConstantValue(p.declarations[0]) : undefined; + return factory.createEnumMember( + unescapeLeadingUnderscores(p.escapedName), + initializedValue === undefined ? undefined : + typeof initializedValue === "string" ? factory.createStringLiteral(initializedValue) : + factory.createNumericLiteral(initializedValue), + ); + }), + ), + modifierFlags, + ); + } + + function serializeAsFunctionNamespaceMerge(type: Type, symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { + const signatures = getSignaturesOfType(type, SignatureKind.Call); + for (const sig of signatures) { + // Each overload becomes a separate function declaration, in order + const decl = signatureToSignatureDeclarationHelper(sig, SyntaxKind.FunctionDeclaration, context, { name: factory.createIdentifier(localName) }) as FunctionDeclaration; + addResult(setTextRange(context, decl, getSignatureTextRangeLocation(sig)), modifierFlags); + } + // Module symbol emit will take care of module-y members, provided it has exports + if (!(symbol.flags & (SymbolFlags.ValueModule | SymbolFlags.NamespaceModule) && !!symbol.exports && !!symbol.exports.size)) { + const props = filter(getPropertiesOfType(type), isNamespaceMember); + serializeAsNamespaceDeclaration(props, localName, modifierFlags, /*suppressNewPrivateContext*/ true); + } + } + + function getSignatureTextRangeLocation(signature: Signature) { + if (signature.declaration && signature.declaration.parent) { + if (isBinaryExpression(signature.declaration.parent) && getAssignmentDeclarationKind(signature.declaration.parent) === AssignmentDeclarationKind.Property) { + return signature.declaration.parent; + } + // for expressions assigned to `var`s, use the `var` as the text range + if (isVariableDeclaration(signature.declaration.parent) && signature.declaration.parent.parent) { + return signature.declaration.parent.parent; + } + } + return signature.declaration; + } + + function serializeAsNamespaceDeclaration(props: readonly Symbol[], localName: string, modifierFlags: ModifierFlags, suppressNewPrivateContext: boolean) { + if (length(props)) { + const localVsRemoteMap = arrayToMultiMap(props, p => !length(p.declarations) || some(p.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(context.enclosingDeclaration!)) ? "local" : "remote"); + const localProps = localVsRemoteMap.get("local") || emptyArray; + // handle remote props first - we need to make an `import` declaration that points at the module containing each remote + // prop in the outermost scope (TODO: a namespace within a namespace would need to be appropriately handled by this) + // Example: + // import Foo_1 = require("./exporter"); + // export namespace ns { + // import Foo = Foo_1.Foo; + // export { Foo }; + // export const c: number; + // } + // This is needed because in JS, statements like `const x = require("./f")` support both type and value lookup, even if they're + // normally just value lookup (so it functions kinda like an alias even when it's not an alias) + // _Usually_, we'll simply print the top-level as an alias instead of a `var` in such situations, however is is theoretically + // possible to encounter a situation where a type has members from both the current file and other files - in those situations, + // emit akin to the above would be needed. + + // Add a namespace + // Create namespace as non-synthetic so it is usable as an enclosing declaration + let fakespace = parseNodeFactory.createModuleDeclaration(/*modifiers*/ undefined, factory.createIdentifier(localName), factory.createModuleBlock([]), NodeFlags.Namespace); + setParent(fakespace, enclosingDeclaration as SourceFile | NamespaceDeclaration); + fakespace.locals = createSymbolTable(props); + fakespace.symbol = props[0].parent!; + + const oldResults = results; + results = []; + const oldAddingDeclare = addingDeclare; + addingDeclare = false; + const subcontext = { ...context, enclosingDeclaration: fakespace }; + const oldContext = context; + context = subcontext; + // TODO: implement handling for the localVsRemoteMap.get("remote") - should be difficult to trigger (see comment above), as only interesting cross-file js merges should make this possible + visitSymbolTable(createSymbolTable(localProps), suppressNewPrivateContext, /*propertyAsAlias*/ true); + context = oldContext; + addingDeclare = oldAddingDeclare; + const declarations = results; + results = oldResults; + // replace namespace with synthetic version + const defaultReplaced = map(declarations, d => + isExportAssignment(d) && !d.isExportEquals && isIdentifier(d.expression) ? factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, d.expression, factory.createIdentifier(InternalSymbolName.Default))]), + ) : d); + const exportModifierStripped = every(defaultReplaced, d => hasSyntacticModifier(d, ModifierFlags.Export)) ? map(defaultReplaced as Extract[], removeExportModifier) : defaultReplaced; + fakespace = factory.updateModuleDeclaration( + fakespace, + fakespace.modifiers, + fakespace.name, + factory.createModuleBlock(exportModifierStripped), + ); + addResult(fakespace, modifierFlags); // namespaces can never be default exported + } + } + + function isNamespaceMember(p: Symbol) { + return !!(p.flags & (SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias)) || + !(p.flags & SymbolFlags.Prototype || p.escapedName === "prototype" || p.valueDeclaration && isStatic(p.valueDeclaration) && isClassLike(p.valueDeclaration.parent)); + } + + function sanitizeJSDocImplements(clauses: readonly ExpressionWithTypeArguments[]): ExpressionWithTypeArguments[] | undefined { + const result = mapDefined(clauses, e => { + const oldEnclosing = context.enclosingDeclaration; + context.enclosingDeclaration = e; + let expr = e.expression; + if (isEntityNameExpression(expr)) { + if (isIdentifier(expr) && idText(expr) === "") { + return cleanup(/*result*/ undefined); // Empty heritage clause, should be an error, but prefer emitting no heritage clauses to reemitting the empty one + } + let introducesError: boolean; + ({ introducesError, node: expr } = trackExistingEntityName(expr, context)); + if (introducesError) { + return cleanup(/*result*/ undefined); + } + } + return cleanup(factory.createExpressionWithTypeArguments( + expr, + map(e.typeArguments, a => + tryReuseExistingNonParameterTypeNode(context, a, getTypeFromTypeNode(context, a)) + || typeToTypeNodeHelper(getTypeFromTypeNode(context, a), context)), + )); + + function cleanup(result: T): T { + context.enclosingDeclaration = oldEnclosing; + return result; + } + }); + if (result.length === clauses.length) { + return result; + } + return undefined; + } + + function serializeAsClass(symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { + const originalDecl = symbol.declarations?.find(isClassLike); + const oldEnclosing = context.enclosingDeclaration; + context.enclosingDeclaration = originalDecl || oldEnclosing; + const localParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + const typeParamDecls = map(localParams, p => typeParameterToDeclaration(p, context)); + const classType = getTypeWithThisArgument(getDeclaredTypeOfClassOrInterface(symbol)) as InterfaceType; + const baseTypes = getBaseTypes(classType); + const originalImplements = originalDecl && getEffectiveImplementsTypeNodes(originalDecl); + const implementsExpressions = originalImplements && sanitizeJSDocImplements(originalImplements) + || mapDefined(getImplementsTypes(classType), serializeImplementedType); + const staticType = getTypeOfSymbol(symbol); + const isClass = !!staticType.symbol?.valueDeclaration && isClassLike(staticType.symbol.valueDeclaration); + const staticBaseType = isClass + ? getBaseConstructorTypeOfClass(staticType as InterfaceType) + : anyType; + const heritageClauses = [ + ...!length(baseTypes) ? [] : [factory.createHeritageClause(SyntaxKind.ExtendsKeyword, map(baseTypes, b => serializeBaseType(b, staticBaseType, localName)))], + ...!length(implementsExpressions) ? [] : [factory.createHeritageClause(SyntaxKind.ImplementsKeyword, implementsExpressions)], + ]; + const symbolProps = getNonInheritedProperties(classType, baseTypes, getPropertiesOfType(classType)); + const publicSymbolProps = filter(symbolProps, s => { + // `valueDeclaration` could be undefined if inherited from + // a union/intersection base type, but inherited properties + // don't matter here. + const valueDecl = s.valueDeclaration; + return !!valueDecl && !(isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name)); + }); + const hasPrivateIdentifier = some(symbolProps, s => { + // `valueDeclaration` could be undefined if inherited from + // a union/intersection base type, but inherited properties + // don't matter here. + const valueDecl = s.valueDeclaration; + return !!valueDecl && isNamedDeclaration(valueDecl) && isPrivateIdentifier(valueDecl.name); + }); + // Boil down all private properties into a single one. + const privateProperties = hasPrivateIdentifier ? + [factory.createPropertyDeclaration( + /*modifiers*/ undefined, + factory.createPrivateIdentifier("#private"), + /*questionOrExclamationToken*/ undefined, + /*type*/ undefined, + /*initializer*/ undefined, + )] : + emptyArray; + const publicProperties = flatMap(publicSymbolProps, p => serializePropertySymbolForClass(p, /*isStatic*/ false, baseTypes[0])); + // Consider static members empty if symbol also has function or module meaning - function namespacey emit will handle statics + const staticMembers = flatMap( + filter(getPropertiesOfType(staticType), p => !(p.flags & SymbolFlags.Prototype) && p.escapedName !== "prototype" && !isNamespaceMember(p)), + p => serializePropertySymbolForClass(p, /*isStatic*/ true, staticBaseType), + ); + // When we encounter an `X.prototype.y` assignment in a JS file, we bind `X` as a class regardless as to whether + // the value is ever initialized with a class or function-like value. For cases where `X` could never be + // created via `new`, we will inject a `private constructor()` declaration to indicate it is not createable. + const isNonConstructableClassLikeInJsFile = !isClass && + !!symbol.valueDeclaration && + isInJSFile(symbol.valueDeclaration) && + !some(getSignaturesOfType(staticType, SignatureKind.Construct)); + const constructors = isNonConstructableClassLikeInJsFile ? + [factory.createConstructorDeclaration(factory.createModifiersFromModifierFlags(ModifierFlags.Private), [], /*body*/ undefined)] : + serializeSignatures(SignatureKind.Construct, staticType, staticBaseType, SyntaxKind.Constructor) as ConstructorDeclaration[]; + const indexSignatures = serializeIndexSignatures(classType, baseTypes[0]); + context.enclosingDeclaration = oldEnclosing; + addResult( + setTextRange( + context, + factory.createClassDeclaration( + /*modifiers*/ undefined, + localName, + typeParamDecls, + heritageClauses, + [...indexSignatures, ...staticMembers, ...constructors, ...publicProperties, ...privateProperties], + ), + symbol.declarations && filter(symbol.declarations, d => isClassDeclaration(d) || isClassExpression(d))[0], + ), + modifierFlags, + ); + } + + function getSomeTargetNameFromDeclarations(declarations: Declaration[] | undefined) { + return firstDefined(declarations, d => { + if (isImportSpecifier(d) || isExportSpecifier(d)) { + return moduleExportNameTextUnescaped(d.propertyName || d.name); + } + if (isBinaryExpression(d) || isExportAssignment(d)) { + const expression = isExportAssignment(d) ? d.expression : d.right; + if (isPropertyAccessExpression(expression)) { + return idText(expression.name); + } + } + if (isAliasSymbolDeclaration(d)) { + // This is... heuristic, at best. But it's probably better than always printing the name of the shorthand ambient module. + const name = getNameOfDeclaration(d); + if (name && isIdentifier(name)) { + return idText(name); + } + } + return undefined; + }); + } + + function serializeAsAlias(symbol: Symbol, localName: string, modifierFlags: ModifierFlags) { + // synthesize an alias, eg `export { symbolName as Name }` + // need to mark the alias `symbol` points at + // as something we need to serialize as a private declaration as well + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + const target = getMergedSymbol(getTargetOfAliasDeclaration(node, /*dontRecursivelyResolve*/ true)); + if (!target) { + return; + } + // If `target` refers to a shorthand module symbol, the name we're trying to pull out isn;t recoverable from the target symbol + // In such a scenario, we must fall back to looking for an alias declaration on `symbol` and pulling the target name from that + let verbatimTargetName = isShorthandAmbientModuleSymbol(target) && getSomeTargetNameFromDeclarations(symbol.declarations) || unescapeLeadingUnderscores(target.escapedName); + if (verbatimTargetName === InternalSymbolName.ExportEquals && allowSyntheticDefaultImports) { + // target refers to an `export=` symbol that was hoisted into a synthetic default - rename here to match + verbatimTargetName = InternalSymbolName.Default; + } + const targetName = getInternalSymbolName(target, verbatimTargetName); + includePrivateSymbol(target); // the target may be within the same scope - attempt to serialize it first + switch (node.kind) { + case SyntaxKind.BindingElement: + if (node.parent?.parent?.kind === SyntaxKind.VariableDeclaration) { + // const { SomeClass } = require('./lib'); + const specifier = getSpecifierForModuleSymbol(target.parent || target, context); // './lib' + const { propertyName } = node as BindingElement; + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause( + /*isTypeOnly*/ false, + /*name*/ undefined, + factory.createNamedImports([factory.createImportSpecifier( + /*isTypeOnly*/ false, + propertyName && isIdentifier(propertyName) ? factory.createIdentifier(idText(propertyName)) : undefined, + factory.createIdentifier(localName), + )]), + ), + factory.createStringLiteral(specifier), + /*attributes*/ undefined, + ), + ModifierFlags.None, + ); + break; + } + // We don't know how to serialize this (nested?) binding element + Debug.failBadSyntaxKind(node.parent?.parent || node, "Unhandled binding element grandparent kind in declaration serialization"); + break; + case SyntaxKind.ShorthandPropertyAssignment: + if (node.parent?.parent?.kind === SyntaxKind.BinaryExpression) { + // module.exports = { SomeClass } + serializeExportSpecifier( + unescapeLeadingUnderscores(symbol.escapedName), + targetName, + ); + } + break; + case SyntaxKind.VariableDeclaration: + // commonjs require: const x = require('y') + if (isPropertyAccessExpression((node as VariableDeclaration).initializer!)) { + // const x = require('y').z + const initializer = (node as VariableDeclaration).initializer! as PropertyAccessExpression; // require('y').z + const uniqueName = factory.createUniqueName(localName); // _x + const specifier = getSpecifierForModuleSymbol(target.parent || target, context); // 'y' + // import _x = require('y'); + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + uniqueName, + factory.createExternalModuleReference(factory.createStringLiteral(specifier)), + ), + ModifierFlags.None, + ); + // import x = _x.z + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createIdentifier(localName), + factory.createQualifiedName(uniqueName, initializer.name as Identifier), + ), + modifierFlags, + ); + break; + } + // else fall through and treat commonjs require just like import= + case SyntaxKind.ImportEqualsDeclaration: + // This _specifically_ only exists to handle json declarations - where we make aliases, but since + // we emit no declarations for the json document, must not refer to it in the declarations + if (target.escapedName === InternalSymbolName.ExportEquals && some(target.declarations, d => isSourceFile(d) && isJsonSourceFile(d))) { + serializeMaybeAliasAssignment(symbol); + break; + } + // Could be a local `import localName = ns.member` or + // an external `import localName = require("whatever")` + const isLocalImport = !(target.flags & SymbolFlags.ValueModule) && !isVariableDeclaration(node); + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createIdentifier(localName), + isLocalImport + ? symbolToName(target, context, SymbolFlags.All, /*expectsIdentifier*/ false) + : factory.createExternalModuleReference(factory.createStringLiteral(getSpecifierForModuleSymbol(target, context))), + ), + isLocalImport ? modifierFlags : ModifierFlags.None, + ); + break; + case SyntaxKind.NamespaceExportDeclaration: + // export as namespace foo + // TODO: Not part of a file's local or export symbol tables + // Is bound into file.symbol.globalExports instead, which we don't currently traverse + addResult(factory.createNamespaceExportDeclaration(idText((node as NamespaceExportDeclaration).name)), ModifierFlags.None); + break; + case SyntaxKind.ImportClause: { + const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects + const specifier = context.bundled ? factory.createStringLiteral(generatedSpecifier) : (node as ImportClause).parent.moduleSpecifier; + const attributes = isImportDeclaration(node.parent) ? node.parent.attributes : undefined; + const isTypeOnly = isJSDocImportTag((node as ImportClause).parent); + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause(isTypeOnly, factory.createIdentifier(localName), /*namedBindings*/ undefined), + specifier, + attributes, + ), + ModifierFlags.None, + ); + break; + } + case SyntaxKind.NamespaceImport: { + const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects + const specifier = context.bundled ? factory.createStringLiteral(generatedSpecifier) : (node as NamespaceImport).parent.parent.moduleSpecifier; + const isTypeOnly = isJSDocImportTag((node as NamespaceImport).parent.parent); + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause(isTypeOnly, /*name*/ undefined, factory.createNamespaceImport(factory.createIdentifier(localName))), + specifier, + (node as ImportClause).parent.attributes, + ), + ModifierFlags.None, + ); + break; + } + case SyntaxKind.NamespaceExport: + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamespaceExport(factory.createIdentifier(localName)), + factory.createStringLiteral(getSpecifierForModuleSymbol(target, context)), + ), + ModifierFlags.None, + ); + break; + case SyntaxKind.ImportSpecifier: { + const generatedSpecifier = getSpecifierForModuleSymbol(target.parent || target, context); // generate specifier (even though we're reusing and existing one) for ambient module reference include side effects + const specifier = context.bundled ? factory.createStringLiteral(generatedSpecifier) : (node as ImportSpecifier).parent.parent.parent.moduleSpecifier; + const isTypeOnly = isJSDocImportTag((node as ImportSpecifier).parent.parent.parent); + addResult( + factory.createImportDeclaration( + /*modifiers*/ undefined, + factory.createImportClause( + isTypeOnly, + /*name*/ undefined, + factory.createNamedImports([ + factory.createImportSpecifier( + /*isTypeOnly*/ false, + localName !== verbatimTargetName ? factory.createIdentifier(verbatimTargetName) : undefined, + factory.createIdentifier(localName), + ), + ]), + ), + specifier, + (node as ImportSpecifier).parent.parent.parent.attributes, + ), + ModifierFlags.None, + ); + break; + } + case SyntaxKind.ExportSpecifier: + // does not use localName because the symbol name in this case refers to the name in the exports table, + // which we must exactly preserve + const specifier = (node.parent.parent as ExportDeclaration).moduleSpecifier; + if (specifier) { + const propertyName = (node as ExportSpecifier).propertyName; + if (propertyName && moduleExportNameIsDefault(propertyName)) { + verbatimTargetName = InternalSymbolName.Default; + } + } + // targetName is only used when the target is local, as otherwise the target is an alias that points at + // another file + serializeExportSpecifier( + unescapeLeadingUnderscores(symbol.escapedName), + specifier ? verbatimTargetName : targetName, + specifier && isStringLiteralLike(specifier) ? factory.createStringLiteral(specifier.text) : undefined, + ); + break; + case SyntaxKind.ExportAssignment: + serializeMaybeAliasAssignment(symbol); + break; + case SyntaxKind.BinaryExpression: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + // Could be best encoded as though an export specifier or as though an export assignment + // If name is default or export=, do an export assignment + // Otherwise do an export specifier + if (symbol.escapedName === InternalSymbolName.Default || symbol.escapedName === InternalSymbolName.ExportEquals) { + serializeMaybeAliasAssignment(symbol); + } + else { + serializeExportSpecifier(localName, targetName); + } + break; + default: + return Debug.failBadSyntaxKind(node, "Unhandled alias declaration kind in symbol serializer!"); + } + } + + function serializeExportSpecifier(localName: string, targetName: string, specifier?: Expression) { + addResult( + factory.createExportDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, localName !== targetName ? targetName : undefined, localName)]), + specifier, + ), + ModifierFlags.None, + ); + } + + /** + * Returns `true` if an export assignment or declaration was produced for the symbol + */ + function serializeMaybeAliasAssignment(symbol: Symbol): boolean { + if (symbol.flags & SymbolFlags.Prototype) { + return false; + } + const name = unescapeLeadingUnderscores(symbol.escapedName); + const isExportEquals = name === InternalSymbolName.ExportEquals; + const isDefault = name === InternalSymbolName.Default; + const isExportAssignmentCompatibleSymbolName = isExportEquals || isDefault; + // synthesize export = ref + // ref should refer to either be a locally scoped symbol which we need to emit, or + // a reference to another namespace/module which we may need to emit an `import` statement for + const aliasDecl = symbol.declarations && getDeclarationOfAliasSymbol(symbol); + // serialize what the alias points to, preserve the declaration's initializer + const target = aliasDecl && getTargetOfAliasDeclaration(aliasDecl, /*dontRecursivelyResolve*/ true); + // If the target resolves and resolves to a thing defined in this file, emit as an alias, otherwise emit as a const + if (target && length(target.declarations) && some(target.declarations, d => getSourceFileOfNode(d) === getSourceFileOfNode(enclosingDeclaration))) { + // In case `target` refers to a namespace member, look at the declaration and serialize the leftmost symbol in it + // eg, `namespace A { export class B {} }; exports = A.B;` + // Technically, this is all that's required in the case where the assignment is an entity name expression + const expr = aliasDecl && ((isExportAssignment(aliasDecl) || isBinaryExpression(aliasDecl)) ? getExportAssignmentExpression(aliasDecl) : getPropertyAssignmentAliasLikeExpression(aliasDecl as ShorthandPropertyAssignment | PropertyAssignment | PropertyAccessExpression)); + const first = expr && isEntityNameExpression(expr) ? getFirstNonModuleExportsIdentifier(expr) : undefined; + const referenced = first && resolveEntityName(first, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, enclosingDeclaration); + if (referenced || target) { + includePrivateSymbol(referenced || target); + } + + // We disable the context's symbol tracker for the duration of this name serialization + // as, by virtue of being here, the name is required to print something, and we don't want to + // issue a visibility error on it. Only anonymous classes that an alias points at _would_ issue + // a visibility error here (as they're not visible within any scope), but we want to hoist them + // into the containing scope anyway, so we want to skip the visibility checks. + const prevDisableTrackSymbol = context.tracker.disableTrackSymbol; + context.tracker.disableTrackSymbol = true; + if (isExportAssignmentCompatibleSymbolName) { + results.push(factory.createExportAssignment( + /*modifiers*/ undefined, + isExportEquals, + symbolToExpression(target, context, SymbolFlags.All), + )); + } + else { + if (first === expr && first) { + // serialize as `export {target as name}` + serializeExportSpecifier(name, idText(first)); + } + else if (expr && isClassExpression(expr)) { + serializeExportSpecifier(name, getInternalSymbolName(target, symbolName(target))); + } + else { + // serialize as `import _Ref = t.arg.et; export { _Ref as name }` + const varName = getUnusedName(name, symbol); + addResult( + factory.createImportEqualsDeclaration( + /*modifiers*/ undefined, + /*isTypeOnly*/ false, + factory.createIdentifier(varName), + symbolToName(target, context, SymbolFlags.All, /*expectsIdentifier*/ false), + ), + ModifierFlags.None, + ); + serializeExportSpecifier(name, varName); + } + } + context.tracker.disableTrackSymbol = prevDisableTrackSymbol; + return true; + } + else { + // serialize as an anonymous property declaration + const varName = getUnusedName(name, symbol); + // We have to use `getWidenedType` here since the object within a json file is unwidened within the file + // (Unwidened types can only exist in expression contexts and should never be serialized) + const typeToSerialize = getWidenedType(getTypeOfSymbol(getMergedSymbol(symbol))); + if (isTypeRepresentableAsFunctionNamespaceMerge(typeToSerialize, symbol)) { + // If there are no index signatures and `typeToSerialize` is an object type, emit as a namespace instead of a const + serializeAsFunctionNamespaceMerge(typeToSerialize, symbol, varName, isExportAssignmentCompatibleSymbolName ? ModifierFlags.None : ModifierFlags.Export); + } + else { + const flags = context.enclosingDeclaration?.kind === SyntaxKind.ModuleDeclaration && (!(symbol.flags & SymbolFlags.Accessor) || symbol.flags & SymbolFlags.SetAccessor) ? NodeFlags.Let : NodeFlags.Const; + const statement = factory.createVariableStatement( + /*modifiers*/ undefined, + factory.createVariableDeclarationList([ + factory.createVariableDeclaration(varName, /*exclamationToken*/ undefined, serializeTypeForDeclaration(context, /*declaration*/ undefined, typeToSerialize, symbol)), + ], flags), + ); + // Inlined JSON types exported with [module.]exports= will already emit an export=, so should use `declare`. + // Otherwise, the type itself should be exported. + addResult( + statement, + target && target.flags & SymbolFlags.Property && target.escapedName === InternalSymbolName.ExportEquals ? ModifierFlags.Ambient + : name === varName ? ModifierFlags.Export + : ModifierFlags.None, + ); + } + if (isExportAssignmentCompatibleSymbolName) { + results.push(factory.createExportAssignment( + /*modifiers*/ undefined, + isExportEquals, + factory.createIdentifier(varName), + )); + return true; + } + else if (name !== varName) { + serializeExportSpecifier(name, varName); + return true; + } + return false; + } + } + + function isTypeRepresentableAsFunctionNamespaceMerge(typeToSerialize: Type, hostSymbol: Symbol) { + // Only object types which are not constructable, or indexable, whose members all come from the + // context source file, and whose property names are all valid identifiers and not late-bound, _and_ + // whose input is not type annotated (if the input symbol has an annotation we can reuse, we should prefer it) + const ctxSrc = getSourceFileOfNode(context.enclosingDeclaration); + return getObjectFlags(typeToSerialize) & (ObjectFlags.Anonymous | ObjectFlags.Mapped) && + !some(typeToSerialize.symbol?.declarations, isTypeNode) && // If the type comes straight from a type node, we shouldn't try to break it up + !length(getIndexInfosOfType(typeToSerialize)) && + !isClassInstanceSide(typeToSerialize) && // While a class instance is potentially representable as a NS, prefer printing a reference to the instance type and serializing the class + !!(length(filter(getPropertiesOfType(typeToSerialize), isNamespaceMember)) || length(getSignaturesOfType(typeToSerialize, SignatureKind.Call))) && + !length(getSignaturesOfType(typeToSerialize, SignatureKind.Construct)) && // TODO: could probably serialize as function + ns + class, now that that's OK + !getDeclarationWithTypeAnnotation(hostSymbol, enclosingDeclaration) && + !(typeToSerialize.symbol && some(typeToSerialize.symbol.declarations, d => getSourceFileOfNode(d) !== ctxSrc)) && + !some(getPropertiesOfType(typeToSerialize), p => isLateBoundName(p.escapedName)) && + !some(getPropertiesOfType(typeToSerialize), p => some(p.declarations, d => getSourceFileOfNode(d) !== ctxSrc)) && + every(getPropertiesOfType(typeToSerialize), p => { + if (!isIdentifierText(symbolName(p), languageVersion)) { + return false; + } + if (!(p.flags & SymbolFlags.Accessor)) { + return true; + } + return getNonMissingTypeOfSymbol(p) === getWriteTypeOfSymbol(p); + }); + } + + function makeSerializePropertySymbol( + createProperty: ( + modifiers: readonly Modifier[] | undefined, + name: string | PropertyName, + questionOrExclamationToken: QuestionToken | undefined, + type: TypeNode | undefined, + initializer: Expression | undefined, + ) => T, + methodKind: SignatureDeclaration["kind"], + useAccessors: true, + ): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => T | AccessorDeclaration | (T | AccessorDeclaration)[]; + function makeSerializePropertySymbol( + createProperty: ( + modifiers: readonly Modifier[] | undefined, + name: string | PropertyName, + questionOrExclamationToken: QuestionToken | undefined, + type: TypeNode | undefined, + initializer: Expression | undefined, + ) => T, + methodKind: SignatureDeclaration["kind"], + useAccessors: false, + ): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => T | T[]; + function makeSerializePropertySymbol( + createProperty: ( + modifiers: readonly Modifier[] | undefined, + name: string | PropertyName, + questionOrExclamationToken: QuestionToken | undefined, + type: TypeNode | undefined, + initializer: Expression | undefined, + ) => T, + methodKind: SignatureDeclaration["kind"], + useAccessors: boolean, + ): (p: Symbol, isStatic: boolean, baseType: Type | undefined) => T | AccessorDeclaration | (T | AccessorDeclaration)[] { + return function serializePropertySymbol(p: Symbol, isStatic: boolean, baseType: Type | undefined): T | AccessorDeclaration | (T | AccessorDeclaration)[] { + const modifierFlags = getDeclarationModifierFlagsFromSymbol(p); + const isPrivate = !!(modifierFlags & ModifierFlags.Private); + if (isStatic && (p.flags & (SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias))) { + // Only value-only-meaning symbols can be correctly encoded as class statics, type/namespace/alias meaning symbols + // need to be merged namespace members + return []; + } + if ( + p.flags & SymbolFlags.Prototype || p.escapedName === "constructor" || + (baseType && getPropertyOfType(baseType, p.escapedName) + && isReadonlySymbol(getPropertyOfType(baseType, p.escapedName)!) === isReadonlySymbol(p) + && (p.flags & SymbolFlags.Optional) === (getPropertyOfType(baseType, p.escapedName)!.flags & SymbolFlags.Optional) + && isTypeIdenticalTo(getTypeOfSymbol(p), getTypeOfPropertyOfType(baseType, p.escapedName)!)) + ) { + return []; + } + const flag = (modifierFlags & ~ModifierFlags.Async) | (isStatic ? ModifierFlags.Static : 0); + const name = getPropertyNameNodeForSymbol(p, context); + const firstPropertyLikeDecl = p.declarations?.find(or(isPropertyDeclaration, isAccessor, isVariableDeclaration, isPropertySignature, isBinaryExpression, isPropertyAccessExpression)); + if (p.flags & SymbolFlags.Accessor && useAccessors) { + const result: AccessorDeclaration[] = []; + if (p.flags & SymbolFlags.SetAccessor) { + const setter = p.declarations && forEach(p.declarations, d => { + if (d.kind === SyntaxKind.SetAccessor) { + return d as SetAccessorDeclaration; + } + if (isCallExpression(d) && isBindableObjectDefinePropertyCall(d)) { + return forEach(d.arguments[2].properties, propDecl => { + const id = getNameOfDeclaration(propDecl); + if (!!id && isIdentifier(id) && idText(id) === "set") { + return propDecl; + } + }); + } + }); + + Debug.assert(!!setter); + const paramSymbol = isFunctionLikeDeclaration(setter) ? getSignatureFromDeclaration(setter).parameters[0] : undefined; + + result.push(setTextRange( + context, + factory.createSetAccessorDeclaration( + factory.createModifiersFromModifierFlags(flag), + name, + [factory.createParameterDeclaration( + /*modifiers*/ undefined, + /*dotDotDotToken*/ undefined, + paramSymbol ? parameterToParameterDeclarationName(paramSymbol, getEffectiveParameterDeclaration(paramSymbol), context) : "value", + /*questionToken*/ undefined, + isPrivate ? undefined : serializeTypeForDeclaration(context, /*declaration*/ undefined, getWriteTypeOfSymbol(p), p), + )], + /*body*/ undefined, + ), + p.declarations?.find(isSetAccessor) || firstPropertyLikeDecl, + )); + } + if (p.flags & SymbolFlags.GetAccessor) { + const isPrivate = modifierFlags & ModifierFlags.Private; + result.push(setTextRange( + context, + factory.createGetAccessorDeclaration( + factory.createModifiersFromModifierFlags(flag), + name, + [], + isPrivate ? undefined : serializeTypeForDeclaration(context, /*declaration*/ undefined, getTypeOfSymbol(p), p), + /*body*/ undefined, + ), + p.declarations?.find(isGetAccessor) || firstPropertyLikeDecl, + )); + } + return result; + } + // This is an else/if as accessors and properties can't merge in TS, but might in JS + // If this happens, we assume the accessor takes priority, as it imposes more constraints + else if (p.flags & (SymbolFlags.Property | SymbolFlags.Variable | SymbolFlags.Accessor)) { + return setTextRange( + context, + createProperty( + factory.createModifiersFromModifierFlags((isReadonlySymbol(p) ? ModifierFlags.Readonly : 0) | flag), + name, + p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + isPrivate ? undefined : serializeTypeForDeclaration(context, /*declaration*/ undefined, getWriteTypeOfSymbol(p), p), + // TODO: https://github.com/microsoft/TypeScript/pull/32372#discussion_r328386357 + // interface members can't have initializers, however class members _can_ + /*initializer*/ undefined, + ), + p.declarations?.find(or(isPropertyDeclaration, isVariableDeclaration)) || firstPropertyLikeDecl, + ); + } + if (p.flags & (SymbolFlags.Method | SymbolFlags.Function)) { + const type = getTypeOfSymbol(p); + const signatures = getSignaturesOfType(type, SignatureKind.Call); + if (flag & ModifierFlags.Private) { + return setTextRange( + context, + createProperty( + factory.createModifiersFromModifierFlags((isReadonlySymbol(p) ? ModifierFlags.Readonly : 0) | flag), + name, + p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + /*type*/ undefined, + /*initializer*/ undefined, + ), + p.declarations?.find(isFunctionLikeDeclaration) || signatures[0] && signatures[0].declaration || p.declarations && p.declarations[0], + ); + } + + const results = []; + for (const sig of signatures) { + // Each overload becomes a separate method declaration, in order + const decl = signatureToSignatureDeclarationHelper( + sig, + methodKind, + context, + { + name, + questionToken: p.flags & SymbolFlags.Optional ? factory.createToken(SyntaxKind.QuestionToken) : undefined, + modifiers: flag ? factory.createModifiersFromModifierFlags(flag) : undefined, + }, + ); + const location = sig.declaration && isPrototypePropertyAssignment(sig.declaration.parent) ? sig.declaration.parent : sig.declaration; + results.push(setTextRange(context, decl, location)); + } + return results as unknown as T[]; + } + // The `Constructor`'s symbol isn't in the class's properties lists, obviously, since it's a signature on the static + return Debug.fail(`Unhandled class member kind! ${(p as any).__debugFlags || p.flags}`); + }; + } + + function serializePropertySymbolForInterface(p: Symbol, baseType: Type | undefined) { + return serializePropertySymbolForInterfaceWorker(p, /*isStatic*/ false, baseType); + } + + function serializeSignatures(kind: SignatureKind, input: Type, baseType: Type | undefined, outputKind: SignatureDeclaration["kind"]) { + const signatures = getSignaturesOfType(input, kind); + if (kind === SignatureKind.Construct) { + if (!baseType && every(signatures, s => length(s.parameters) === 0)) { + return []; // No base type, every constructor is empty - elide the extraneous `constructor()` + } + if (baseType) { + // If there is a base type, if every signature in the class is identical to a signature in the baseType, elide all the declarations + const baseSigs = getSignaturesOfType(baseType, SignatureKind.Construct); + if (!length(baseSigs) && every(signatures, s => length(s.parameters) === 0)) { + return []; // Base had no explicit signatures, if all our signatures are also implicit, return an empty list + } + if (baseSigs.length === signatures.length) { + let failed = false; + for (let i = 0; i < baseSigs.length; i++) { + if (!compareSignaturesIdentical(signatures[i], baseSigs[i], /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true, compareTypesIdentical)) { + failed = true; + break; + } + } + if (!failed) { + return []; // Every signature was identical - elide constructor list as it is inherited + } + } + } + let privateProtected: ModifierFlags = 0; + for (const s of signatures) { + if (s.declaration) { + privateProtected |= getSelectedEffectiveModifierFlags(s.declaration, ModifierFlags.Private | ModifierFlags.Protected); + } + } + if (privateProtected) { + return [setTextRange( + context, + factory.createConstructorDeclaration( + factory.createModifiersFromModifierFlags(privateProtected), + /*parameters*/ [], + /*body*/ undefined, + ), + signatures[0].declaration, + )]; + } + } + + const results = []; + for (const sig of signatures) { + // Each overload becomes a separate constructor declaration, in order + const decl = signatureToSignatureDeclarationHelper(sig, outputKind, context); + results.push(setTextRange(context, decl, sig.declaration)); + } + return results; + } + + function serializeIndexSignatures(input: Type, baseType: Type | undefined) { + const results: IndexSignatureDeclaration[] = []; + for (const info of getIndexInfosOfType(input)) { + if (baseType) { + const baseInfo = getIndexInfoOfType(baseType, info.keyType); + if (baseInfo) { + if (isTypeIdenticalTo(info.type, baseInfo.type)) { + continue; // elide identical index signatures + } + } + } + results.push(indexInfoToIndexSignatureDeclarationHelper(info, context, /*typeNode*/ undefined)); + } + return results; + } + + function serializeBaseType(t: Type, staticType: Type, rootName: string) { + const ref = trySerializeAsTypeReference(t, SymbolFlags.Value); + if (ref) { + return ref; + } + const tempName = getUnusedName(`${rootName}_base`); + const statement = factory.createVariableStatement( + /*modifiers*/ undefined, + factory.createVariableDeclarationList([ + factory.createVariableDeclaration(tempName, /*exclamationToken*/ undefined, typeToTypeNodeHelper(staticType, context)), + ], NodeFlags.Const), + ); + addResult(statement, ModifierFlags.None); + return factory.createExpressionWithTypeArguments(factory.createIdentifier(tempName), /*typeArguments*/ undefined); + } + + function trySerializeAsTypeReference(t: Type, flags: SymbolFlags) { + let typeArgs: TypeNode[] | undefined; + let reference: Expression | undefined; + + // We don't use `isValueSymbolAccessible` below. since that considers alternative containers (like modules) + // which we can't write out in a syntactically valid way as an expression + if ((t as TypeReference).target && isSymbolAccessibleByFlags((t as TypeReference).target.symbol, enclosingDeclaration, flags)) { + typeArgs = map(getTypeArguments(t as TypeReference), t => typeToTypeNodeHelper(t, context)); + reference = symbolToExpression((t as TypeReference).target.symbol, context, SymbolFlags.Type); + } + else if (t.symbol && isSymbolAccessibleByFlags(t.symbol, enclosingDeclaration, flags)) { + reference = symbolToExpression(t.symbol, context, SymbolFlags.Type); + } + if (reference) { + return factory.createExpressionWithTypeArguments(reference, typeArgs); + } + } + + function serializeImplementedType(t: Type) { + const ref = trySerializeAsTypeReference(t, SymbolFlags.Type); + if (ref) { + return ref; + } + if (t.symbol) { + return factory.createExpressionWithTypeArguments(symbolToExpression(t.symbol, context, SymbolFlags.Type), /*typeArguments*/ undefined); + } + } + + function getUnusedName(input: string, symbol?: Symbol): string { + const id = symbol ? getSymbolId(symbol) : undefined; + if (id) { + if (context.remappedSymbolNames!.has(id)) { + return context.remappedSymbolNames!.get(id)!; + } + } + if (symbol) { + input = getNameCandidateWorker(symbol, input); + } + let i = 0; + const original = input; + while (context.usedSymbolNames?.has(input)) { + i++; + input = `${original}_${i}`; + } + context.usedSymbolNames?.add(input); + if (id) { + context.remappedSymbolNames!.set(id, input); + } + return input; + } + + function getNameCandidateWorker(symbol: Symbol, localName: string) { + if (localName === InternalSymbolName.Default || localName === InternalSymbolName.Class || localName === InternalSymbolName.Function) { + const flags = context.flags; + context.flags |= NodeBuilderFlags.InInitialEntityName; + const nameCandidate = getNameOfSymbolAsWritten(symbol, context); + context.flags = flags; + localName = nameCandidate.length > 0 && isSingleOrDoubleQuote(nameCandidate.charCodeAt(0)) ? stripQuotes(nameCandidate) : nameCandidate; + } + if (localName === InternalSymbolName.Default) { + localName = "_default"; + } + else if (localName === InternalSymbolName.ExportEquals) { + localName = "_exports"; + } + localName = isIdentifierText(localName, languageVersion) && !isStringANonContextualKeyword(localName) ? localName : "_" + localName.replace(/[^a-zA-Z0-9]/g, "_"); + return localName; + } + + function getInternalSymbolName(symbol: Symbol, localName: string) { + const id = getSymbolId(symbol); + if (context.remappedSymbolNames!.has(id)) { + return context.remappedSymbolNames!.get(id)!; + } + localName = getNameCandidateWorker(symbol, localName); + // The result of this is going to be used as the symbol's name - lock it in, so `getUnusedName` will also pick it up + context.remappedSymbolNames!.set(id, localName); + return localName; + } + } + } + + function typePredicateToString(typePredicate: TypePredicate, enclosingDeclaration?: Node, flags: TypeFormatFlags = TypeFormatFlags.UseAliasDefinedOutsideCurrentScope, writer?: EmitTextWriter): string { + return writer ? typePredicateToStringWorker(writer).getText() : usingSingleLineStringWriter(typePredicateToStringWorker); + + function typePredicateToStringWorker(writer: EmitTextWriter) { + const nodeBuilderFlags = toNodeBuilderFlags(flags) | NodeBuilderFlags.IgnoreErrors | NodeBuilderFlags.WriteTypeParametersInQualifiedName; + const predicate = nodeBuilder.typePredicateToTypePredicateNode(typePredicate, enclosingDeclaration, nodeBuilderFlags)!; // TODO: GH#18217 + const printer = createPrinterWithRemoveComments(); + const sourceFile = enclosingDeclaration && getSourceFileOfNode(enclosingDeclaration); + printer.writeNode(EmitHint.Unspecified, predicate, /*sourceFile*/ sourceFile, writer); + return writer; + } + } + + function formatUnionTypes(types: readonly Type[]): Type[] { + const result: Type[] = []; + let flags = 0 as TypeFlags; + for (let i = 0; i < types.length; i++) { + const t = types[i]; + flags |= t.flags; + if (!(t.flags & TypeFlags.Nullable)) { + if (t.flags & (TypeFlags.BooleanLiteral | TypeFlags.EnumLike)) { + const baseType = t.flags & TypeFlags.BooleanLiteral ? booleanType : getBaseTypeOfEnumLikeType(t as LiteralType); + if (baseType.flags & TypeFlags.Union) { + const count = (baseType as UnionType).types.length; + if (i + count <= types.length && getRegularTypeOfLiteralType(types[i + count - 1]) === getRegularTypeOfLiteralType((baseType as UnionType).types[count - 1])) { + result.push(baseType); + i += count - 1; + continue; + } + } + } + result.push(t); + } + } + if (flags & TypeFlags.Null) result.push(nullType); + if (flags & TypeFlags.Undefined) result.push(undefinedType); + return result || types; + } + + function visibilityToString(flags: ModifierFlags): string { + if (flags === ModifierFlags.Private) { + return "private"; + } + if (flags === ModifierFlags.Protected) { + return "protected"; + } + return "public"; + } + + function getTypeAliasForTypeLiteral(type: Type): Symbol | undefined { + if (type.symbol && type.symbol.flags & SymbolFlags.TypeLiteral && type.symbol.declarations) { + const node = walkUpParenthesizedTypes(type.symbol.declarations[0].parent); + if (isTypeAliasDeclaration(node)) { + return getSymbolOfDeclaration(node); + } + } + return undefined; + } + + function isTopLevelInExternalModuleAugmentation(node: Node): boolean { + return node && node.parent && + node.parent.kind === SyntaxKind.ModuleBlock && + isExternalModuleAugmentation(node.parent.parent); + } + + function isDefaultBindingContext(location: Node) { + return location.kind === SyntaxKind.SourceFile || isAmbientModule(location); + } + + function getNameOfSymbolFromNameType(symbol: Symbol, context?: NodeBuilderContext) { + const nameType = getSymbolLinks(symbol).nameType; + if (nameType) { + if (nameType.flags & TypeFlags.StringOrNumberLiteral) { + const name = "" + (nameType as StringLiteralType | NumberLiteralType).value; + if (!isIdentifierText(name, getEmitScriptTarget(compilerOptions)) && !isNumericLiteralName(name)) { + return `"${escapeString(name, CharacterCodes.doubleQuote)}"`; + } + if (isNumericLiteralName(name) && startsWith(name, "-")) { + return `[${name}]`; + } + return name; + } + if (nameType.flags & TypeFlags.UniqueESSymbol) { + return `[${getNameOfSymbolAsWritten((nameType as UniqueESSymbolType).symbol, context)}]`; + } + } + } + + /** + * Gets a human-readable name for a symbol. + * Should *not* be used for the right-hand side of a `.` -- use `symbolName(symbol)` for that instead. + * + * Unlike `symbolName(symbol)`, this will include quotes if the name is from a string literal. + * It will also use a representation of a number as written instead of a decimal form, e.g. `0o11` instead of `9`. + */ + function getNameOfSymbolAsWritten(symbol: Symbol, context?: NodeBuilderContext): string { + if (context?.remappedSymbolReferences?.has(getSymbolId(symbol))) { + symbol = context.remappedSymbolReferences.get(getSymbolId(symbol))!; + } + if ( + context && symbol.escapedName === InternalSymbolName.Default && !(context.flags & NodeBuilderFlags.UseAliasDefinedOutsideCurrentScope) && + // If it's not the first part of an entity name, it must print as `default` + (!(context.flags & NodeBuilderFlags.InInitialEntityName) || + // if the symbol is synthesized, it will only be referenced externally it must print as `default` + !symbol.declarations || + // if not in the same binding context (source file, module declaration), it must print as `default` + (context.enclosingDeclaration && findAncestor(symbol.declarations[0], isDefaultBindingContext) !== findAncestor(context.enclosingDeclaration, isDefaultBindingContext))) + ) { + return "default"; + } + if (symbol.declarations && symbol.declarations.length) { + let declaration = firstDefined(symbol.declarations, d => getNameOfDeclaration(d) ? d : undefined); // Try using a declaration with a name, first + const name = declaration && getNameOfDeclaration(declaration); + if (declaration && name) { + if (isCallExpression(declaration) && isBindableObjectDefinePropertyCall(declaration)) { + return symbolName(symbol); + } + if (isComputedPropertyName(name) && !(getCheckFlags(symbol) & CheckFlags.Late)) { + const nameType = getSymbolLinks(symbol).nameType; + if (nameType && nameType.flags & TypeFlags.StringOrNumberLiteral) { + // Computed property name isn't late bound, but has a well-known name type - use name type to generate a symbol name + const result = getNameOfSymbolFromNameType(symbol, context); + if (result !== undefined) { + return result; + } + } + } + return declarationNameToString(name); + } + if (!declaration) { + declaration = symbol.declarations[0]; // Declaration may be nameless, but we'll try anyway + } + if (declaration.parent && declaration.parent.kind === SyntaxKind.VariableDeclaration) { + return declarationNameToString((declaration.parent as VariableDeclaration).name); + } + switch (declaration.kind) { + case SyntaxKind.ClassExpression: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + if (context && !context.encounteredError && !(context.flags & NodeBuilderFlags.AllowAnonymousIdentifier)) { + context.encounteredError = true; + } + return declaration.kind === SyntaxKind.ClassExpression ? "(Anonymous class)" : "(Anonymous function)"; + } + } + const name = getNameOfSymbolFromNameType(symbol, context); + return name !== undefined ? name : symbolName(symbol); + } + + function isDeclarationVisible(node: Node): boolean { + if (node) { + const links = getNodeLinks(node); + if (links.isVisible === undefined) { + links.isVisible = !!determineIfDeclarationIsVisible(); + } + return links.isVisible; + } + + return false; + + function determineIfDeclarationIsVisible() { + switch (node.kind) { + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocEnumTag: + // Top-level jsdoc type aliases are considered exported + // First parent is comment node, second is hosting declaration or token; we only care about those tokens or declarations whose parent is a source file + return !!(node.parent && node.parent.parent && node.parent.parent.parent && isSourceFile(node.parent.parent.parent)); + case SyntaxKind.BindingElement: + return isDeclarationVisible(node.parent.parent); + case SyntaxKind.VariableDeclaration: + if ( + isBindingPattern((node as VariableDeclaration).name) && + !((node as VariableDeclaration).name as BindingPattern).elements.length + ) { + // If the binding pattern is empty, this variable declaration is not visible + return false; + } + // falls through + case SyntaxKind.ModuleDeclaration: + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.ImportEqualsDeclaration: + // external module augmentation is always visible + if (isExternalModuleAugmentation(node)) { + return true; + } + const parent = getDeclarationContainer(node); + // If the node is not exported or it is not ambient module element (except import declaration) + if ( + !(getCombinedModifierFlagsCached(node as Declaration) & ModifierFlags.Export) && + !(node.kind !== SyntaxKind.ImportEqualsDeclaration && parent.kind !== SyntaxKind.SourceFile && parent.flags & NodeFlags.Ambient) + ) { + return isGlobalSourceFile(parent); + } + // Exported members/ambient module elements (exception import declaration) are visible if parent is visible + return isDeclarationVisible(parent); + + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + if (hasEffectiveModifier(node, ModifierFlags.Private | ModifierFlags.Protected)) { + // Private/protected properties/methods are not visible + return false; + } + // Public properties/methods are visible if its parents are visible, so: + // falls through + + case SyntaxKind.Constructor: + case SyntaxKind.ConstructSignature: + case SyntaxKind.CallSignature: + case SyntaxKind.IndexSignature: + case SyntaxKind.Parameter: + case SyntaxKind.ModuleBlock: + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.TypeLiteral: + case SyntaxKind.TypeReference: + case SyntaxKind.ArrayType: + case SyntaxKind.TupleType: + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + case SyntaxKind.ParenthesizedType: + case SyntaxKind.NamedTupleMember: + return isDeclarationVisible(node.parent); + + // Default binding, import specifier and namespace import is visible + // only on demand so by default it is not visible + case SyntaxKind.ImportClause: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportSpecifier: + return false; + + // Type parameters are always visible + case SyntaxKind.TypeParameter: + + // Source file and namespace export are always visible + // falls through + case SyntaxKind.SourceFile: + case SyntaxKind.NamespaceExportDeclaration: + return true; + + // Export assignments do not create name bindings outside the module + case SyntaxKind.ExportAssignment: + return false; + + default: + return false; + } + } + } + + function collectLinkedAliases(node: ModuleExportName, setVisibility?: boolean): Node[] | undefined { + let exportSymbol: Symbol | undefined; + if (node.kind !== SyntaxKind.StringLiteral && node.parent && node.parent.kind === SyntaxKind.ExportAssignment) { + exportSymbol = resolveName(node, node, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + } + else if (node.parent.kind === SyntaxKind.ExportSpecifier) { + exportSymbol = getTargetOfExportSpecifier(node.parent as ExportSpecifier, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias); + } + let result: Node[] | undefined; + let visited: Set | undefined; + if (exportSymbol) { + visited = new Set(); + visited.add(getSymbolId(exportSymbol)); + buildVisibleNodeList(exportSymbol.declarations); + } + return result; + + function buildVisibleNodeList(declarations: Declaration[] | undefined) { + forEach(declarations, declaration => { + const resultNode = getAnyImportSyntax(declaration) || declaration; + if (setVisibility) { + getNodeLinks(declaration).isVisible = true; + } + else { + result = result || []; + pushIfUnique(result, resultNode); + } + + if (isInternalModuleImportEqualsDeclaration(declaration)) { + // Add the referenced top container visible + const internalModuleReference = declaration.moduleReference as Identifier | QualifiedName; + const firstIdentifier = getFirstIdentifier(internalModuleReference); + const importSymbol = resolveName(declaration, firstIdentifier.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (importSymbol && visited) { + if (tryAddToSet(visited, getSymbolId(importSymbol))) { + buildVisibleNodeList(importSymbol.declarations); + } + } + } + }); + } + } + + /** + * Push an entry on the type resolution stack. If an entry with the given target and the given property name + * is already on the stack, and no entries in between already have a type, then a circularity has occurred. + * In this case, the result values of the existing entry and all entries pushed after it are changed to false, + * and the value false is returned. Otherwise, the new entry is just pushed onto the stack, and true is returned. + * In order to see if the same query has already been done before, the target object and the propertyName both + * must match the one passed in. + * + * @param target The symbol, type, or signature whose type is being queried + * @param propertyName The property name that should be used to query the target for its type + */ + function pushTypeResolution(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): boolean { + const resolutionCycleStartIndex = findResolutionCycleStartIndex(target, propertyName); + if (resolutionCycleStartIndex >= 0) { + // A cycle was found + const { length } = resolutionTargets; + for (let i = resolutionCycleStartIndex; i < length; i++) { + resolutionResults[i] = false; + } + return false; + } + resolutionTargets.push(target); + resolutionResults.push(/*items*/ true); + resolutionPropertyNames.push(propertyName); + return true; + } + + function findResolutionCycleStartIndex(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): number { + for (let i = resolutionTargets.length - 1; i >= resolutionStart; i--) { + if (resolutionTargetHasProperty(resolutionTargets[i], resolutionPropertyNames[i])) { + return -1; + } + if (resolutionTargets[i] === target && resolutionPropertyNames[i] === propertyName) { + return i; + } + } + return -1; + } + + function resolutionTargetHasProperty(target: TypeSystemEntity, propertyName: TypeSystemPropertyName): boolean { + switch (propertyName) { + case TypeSystemPropertyName.Type: + return !!getSymbolLinks(target as Symbol).type; + case TypeSystemPropertyName.DeclaredType: + return !!getSymbolLinks(target as Symbol).declaredType; + case TypeSystemPropertyName.ResolvedBaseConstructorType: + return !!(target as InterfaceType).resolvedBaseConstructorType; + case TypeSystemPropertyName.ResolvedReturnType: + return !!(target as Signature).resolvedReturnType; + case TypeSystemPropertyName.ImmediateBaseConstraint: + return !!(target as Type).immediateBaseConstraint; + case TypeSystemPropertyName.ResolvedTypeArguments: + return !!(target as TypeReference).resolvedTypeArguments; + case TypeSystemPropertyName.ResolvedBaseTypes: + return !!(target as InterfaceType).baseTypesResolved; + case TypeSystemPropertyName.WriteType: + return !!getSymbolLinks(target as Symbol).writeType; + case TypeSystemPropertyName.ParameterInitializerContainsUndefined: + return getNodeLinks(target as ParameterDeclaration).parameterInitializerContainsUndefined !== undefined; + } + return Debug.assertNever(propertyName); + } + + /** + * Pop an entry from the type resolution stack and return its associated result value. The result value will + * be true if no circularities were detected, or false if a circularity was found. + */ + function popTypeResolution(): boolean { + resolutionTargets.pop(); + resolutionPropertyNames.pop(); + return resolutionResults.pop()!; + } + + function getDeclarationContainer(node: Node): Node { + return findAncestor(getRootDeclaration(node), node => { + switch (node.kind) { + case SyntaxKind.VariableDeclaration: + case SyntaxKind.VariableDeclarationList: + case SyntaxKind.ImportSpecifier: + case SyntaxKind.NamedImports: + case SyntaxKind.NamespaceImport: + case SyntaxKind.ImportClause: + return false; + default: + return true; + } + })!.parent; + } + + function getTypeOfPrototypeProperty(prototype: Symbol): Type { + // TypeScript 1.0 spec (April 2014): 8.4 + // Every class automatically contains a static property member named 'prototype', + // the type of which is an instantiation of the class type with type Any supplied as a type argument for each type parameter. + // It is an error to explicitly declare a static property member with the name 'prototype'. + const classType = getDeclaredTypeOfSymbol(getParentOfSymbol(prototype)!) as InterfaceType; + return classType.typeParameters ? createTypeReference(classType as GenericType, map(classType.typeParameters, _ => anyType)) : classType; + } + + // Return the type of the given property in the given type, or undefined if no such property exists + function getTypeOfPropertyOfType(type: Type, name: __String): Type | undefined { + const prop = getPropertyOfType(type, name); + return prop ? getTypeOfSymbol(prop) : undefined; + } + + /** + * Return the type of the matching property or index signature in the given type, or undefined + * if no matching property or index signature exists. Add optionality to index signature types. + */ + function getTypeOfPropertyOrIndexSignatureOfType(type: Type, name: __String): Type | undefined { + let propType; + return getTypeOfPropertyOfType(type, name) || + (propType = getApplicableIndexInfoForName(type, name)?.type) && + addOptionality(propType, /*isProperty*/ true, /*isOptional*/ true); + } + + function isTypeAny(type: Type | undefined) { + return type && (type.flags & TypeFlags.Any) !== 0; + } + + function isErrorType(type: Type) { + // The only 'any' types that have alias symbols are those manufactured by getTypeFromTypeAliasReference for + // a reference to an unresolved symbol. We want those to behave like the errorType. + return type === errorType || !!(type.flags & TypeFlags.Any && type.aliasSymbol); + } + + // Return the type of a binding element parent. We check SymbolLinks first to see if a type has been + // assigned by contextual typing. + function getTypeForBindingElementParent(node: BindingElementGrandparent, checkMode: CheckMode) { + if (checkMode !== CheckMode.Normal) { + return getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ false, checkMode); + } + const symbol = getSymbolOfDeclaration(node); + return symbol && getSymbolLinks(symbol).type || getTypeForVariableLikeDeclaration(node, /*includeOptionality*/ false, checkMode); + } + + function getRestType(source: Type, properties: PropertyName[], symbol: Symbol | undefined): Type { + source = filterType(source, t => !(t.flags & TypeFlags.Nullable)); + if (source.flags & TypeFlags.Never) { + return emptyObjectType; + } + if (source.flags & TypeFlags.Union) { + return mapType(source, t => getRestType(t, properties, symbol)); + } + + let omitKeyType = getUnionType(map(properties, getLiteralTypeFromPropertyName)); + + const spreadableProperties: Symbol[] = []; + const unspreadableToRestKeys: Type[] = []; + + for (const prop of getPropertiesOfType(source)) { + const literalTypeFromProperty = getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique); + if ( + !isTypeAssignableTo(literalTypeFromProperty, omitKeyType) + && !(getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) + && isSpreadableProperty(prop) + ) { + spreadableProperties.push(prop); + } + else { + unspreadableToRestKeys.push(literalTypeFromProperty); + } + } + + if (isGenericObjectType(source) || isGenericIndexType(omitKeyType)) { + if (unspreadableToRestKeys.length) { + // If the type we're spreading from has properties that cannot + // be spread into the rest type (e.g. getters, methods), ensure + // they are explicitly omitted, as they would in the non-generic case. + omitKeyType = getUnionType([omitKeyType, ...unspreadableToRestKeys]); + } + + if (omitKeyType.flags & TypeFlags.Never) { + return source; + } + + const omitTypeAlias = getGlobalOmitSymbol(); + if (!omitTypeAlias) { + return errorType; + } + return getTypeAliasInstantiation(omitTypeAlias, [source, omitKeyType]); + } + const members = createSymbolTable(); + for (const prop of spreadableProperties) { + members.set(prop.escapedName, getSpreadSymbol(prop, /*readonly*/ false)); + } + const result = createAnonymousType(symbol, members, emptyArray, emptyArray, getIndexInfosOfType(source)); + result.objectFlags |= ObjectFlags.ObjectRestType; + return result; + } + + function isGenericTypeWithUndefinedConstraint(type: Type) { + return !!(type.flags & TypeFlags.Instantiable) && maybeTypeOfKind(getBaseConstraintOfType(type) || unknownType, TypeFlags.Undefined); + } + + function getNonUndefinedType(type: Type) { + const typeOrConstraint = someType(type, isGenericTypeWithUndefinedConstraint) ? mapType(type, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOrType(t) : t) : type; + return getTypeWithFacts(typeOrConstraint, TypeFacts.NEUndefined); + } + + // Determine the control flow type associated with a destructuring declaration or assignment. The following + // forms of destructuring are possible: + // let { x } = obj; // BindingElement + // let [ x ] = obj; // BindingElement + // { x } = obj; // ShorthandPropertyAssignment + // { x: v } = obj; // PropertyAssignment + // [ x ] = obj; // Expression + // We construct a synthetic element access expression corresponding to 'obj.x' such that the control + // flow analyzer doesn't have to handle all the different syntactic forms. + function getFlowTypeOfDestructuring(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression, declaredType: Type) { + const reference = getSyntheticElementAccess(node); + return reference ? getFlowTypeOfReference(reference, declaredType) : declaredType; + } + + function getSyntheticElementAccess(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression): ElementAccessExpression | undefined { + const parentAccess = getParentElementAccess(node); + if (parentAccess && canHaveFlowNode(parentAccess) && parentAccess.flowNode) { + const propName = getDestructuringPropertyName(node); + if (propName) { + const literal = setTextRangeWorker(parseNodeFactory.createStringLiteral(propName), node); + const lhsExpr = isLeftHandSideExpression(parentAccess) ? parentAccess : parseNodeFactory.createParenthesizedExpression(parentAccess); + const result = setTextRangeWorker(parseNodeFactory.createElementAccessExpression(lhsExpr, literal), node); + setParent(literal, result); + setParent(result, node); + if (lhsExpr !== parentAccess) { + setParent(lhsExpr, result); + } + result.flowNode = parentAccess.flowNode; + return result; + } + } + } + + function getParentElementAccess(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression) { + const ancestor = node.parent.parent; + switch (ancestor.kind) { + case SyntaxKind.BindingElement: + case SyntaxKind.PropertyAssignment: + return getSyntheticElementAccess(ancestor as BindingElement | PropertyAssignment); + case SyntaxKind.ArrayLiteralExpression: + return getSyntheticElementAccess(node.parent as Expression); + case SyntaxKind.VariableDeclaration: + return (ancestor as VariableDeclaration).initializer; + case SyntaxKind.BinaryExpression: + return (ancestor as BinaryExpression).right; + } + } + + function getDestructuringPropertyName(node: BindingElement | PropertyAssignment | ShorthandPropertyAssignment | Expression) { + const parent = node.parent; + if (node.kind === SyntaxKind.BindingElement && parent.kind === SyntaxKind.ObjectBindingPattern) { + return getLiteralPropertyNameText((node as BindingElement).propertyName || (node as BindingElement).name as Identifier); + } + if (node.kind === SyntaxKind.PropertyAssignment || node.kind === SyntaxKind.ShorthandPropertyAssignment) { + return getLiteralPropertyNameText((node as PropertyAssignment | ShorthandPropertyAssignment).name); + } + return "" + ((parent as BindingPattern | ArrayLiteralExpression).elements as NodeArray).indexOf(node); + } + + function getLiteralPropertyNameText(name: PropertyName) { + const type = getLiteralTypeFromPropertyName(name); + return type.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral) ? "" + (type as StringLiteralType | NumberLiteralType).value : undefined; + } + + /** Return the inferred type for a binding element */ + function getTypeForBindingElement(declaration: BindingElement): Type | undefined { + const checkMode = declaration.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal; + const parentType = getTypeForBindingElementParent(declaration.parent.parent, checkMode); + return parentType && getBindingElementTypeFromParentType(declaration, parentType, /*noTupleBoundsCheck*/ false); + } + + function getBindingElementTypeFromParentType(declaration: BindingElement, parentType: Type, noTupleBoundsCheck: boolean): Type { + // If an any type was inferred for parent, infer that for the binding element + if (isTypeAny(parentType)) { + return parentType; + } + const pattern = declaration.parent; + // Relax null check on ambient destructuring parameters, since the parameters have no implementation and are just documentation + if (strictNullChecks && declaration.flags & NodeFlags.Ambient && isPartOfParameterDeclaration(declaration)) { + parentType = getNonNullableType(parentType); + } + // Filter `undefined` from the type we check against if the parent has an initializer and that initializer is not possibly `undefined` + else if (strictNullChecks && pattern.parent.initializer && !(hasTypeFacts(getTypeOfInitializer(pattern.parent.initializer), TypeFacts.EQUndefined))) { + parentType = getTypeWithFacts(parentType, TypeFacts.NEUndefined); + } + + let type: Type | undefined; + if (pattern.kind === SyntaxKind.ObjectBindingPattern) { + if (declaration.dotDotDotToken) { + parentType = getReducedType(parentType); + if (parentType.flags & TypeFlags.Unknown || !isValidSpreadType(parentType)) { + error(declaration, Diagnostics.Rest_types_may_only_be_created_from_object_types); + return errorType; + } + const literalMembers: PropertyName[] = []; + for (const element of pattern.elements) { + if (!element.dotDotDotToken) { + literalMembers.push(element.propertyName || element.name as Identifier); + } + } + type = getRestType(parentType, literalMembers, declaration.symbol); + } + else { + // Use explicitly specified property name ({ p: xxx } form), or otherwise the implied name ({ p } form) + const name = declaration.propertyName || declaration.name as Identifier; + const indexType = getLiteralTypeFromPropertyName(name); + const declaredType = getIndexedAccessType(parentType, indexType, AccessFlags.ExpressionPosition, name); + type = getFlowTypeOfDestructuring(declaration, declaredType); + } + } + else { + // This elementType will be used if the specific property corresponding to this index is not + // present (aka the tuple element property). This call also checks that the parentType is in + // fact an iterable or array (depending on target language). + const elementType = checkIteratedTypeOrElementType(IterationUse.Destructuring | (declaration.dotDotDotToken ? 0 : IterationUse.PossiblyOutOfBounds), parentType, undefinedType, pattern); + const index = pattern.elements.indexOf(declaration); + if (declaration.dotDotDotToken) { + // If the parent is a tuple type, the rest element has a tuple type of the + // remaining tuple element types. Otherwise, the rest element has an array type with same + // element type as the parent type. + const baseConstraint = mapType(parentType, t => t.flags & TypeFlags.InstantiableNonPrimitive ? getBaseConstraintOrType(t) : t); + type = everyType(baseConstraint, isTupleType) ? + mapType(baseConstraint, t => sliceTupleType(t as TupleTypeReference, index)) : + createArrayType(elementType); + } + else if (isArrayLikeType(parentType)) { + const indexType = getNumberLiteralType(index); + const accessFlags = AccessFlags.ExpressionPosition | (noTupleBoundsCheck || hasDefaultValue(declaration) ? AccessFlags.NoTupleBoundsCheck : 0); + const declaredType = getIndexedAccessTypeOrUndefined(parentType, indexType, accessFlags, declaration.name) || errorType; + type = getFlowTypeOfDestructuring(declaration, declaredType); + } + else { + type = elementType; + } + } + if (!declaration.initializer) { + return type; + } + if (getEffectiveTypeAnnotationNode(walkUpBindingElementsAndPatterns(declaration))) { + // In strict null checking mode, if a default value of a non-undefined type is specified, remove + // undefined from the final type. + return strictNullChecks && !(hasTypeFacts(checkDeclarationInitializer(declaration, CheckMode.Normal), TypeFacts.IsUndefined)) ? getNonUndefinedType(type) : type; + } + return widenTypeInferredFromInitializer(declaration, getUnionType([getNonUndefinedType(type), checkDeclarationInitializer(declaration, CheckMode.Normal)], UnionReduction.Subtype)); + } + + function getTypeForDeclarationFromJSDocComment(declaration: Node) { + const jsdocType = getJSDocType(declaration); + if (jsdocType) { + return getTypeFromTypeNode(jsdocType); + } + return undefined; + } + + function isNullOrUndefined(node: Expression) { + const expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + return expr.kind === SyntaxKind.NullKeyword || expr.kind === SyntaxKind.Identifier && getResolvedSymbol(expr as Identifier) === undefinedSymbol; + } + + function isEmptyArrayLiteral(node: Expression) { + const expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + return expr.kind === SyntaxKind.ArrayLiteralExpression && (expr as ArrayLiteralExpression).elements.length === 0; + } + + function addOptionality(type: Type, isProperty = false, isOptional = true): Type { + return strictNullChecks && isOptional ? getOptionalType(type, isProperty) : type; + } + + // Return the inferred type for a variable, parameter, or property declaration + function getTypeForVariableLikeDeclaration( + declaration: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement | JSDocPropertyLikeTag, + includeOptionality: boolean, + checkMode: CheckMode, + ): Type | undefined { + // A variable declared in a for..in statement is of type string, or of type keyof T when the + // right hand expression is of a type parameter type. + if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForInStatement) { + const indexType = getIndexType(getNonNullableTypeIfNeeded(checkExpression(declaration.parent.parent.expression, /*checkMode*/ checkMode))); + return indexType.flags & (TypeFlags.TypeParameter | TypeFlags.Index) ? getExtractStringType(indexType) : stringType; + } + + if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForOfStatement) { + // checkRightHandSideOfForOf will return undefined if the for-of expression type was + // missing properties/signatures required to get its iteratedType (like + // [Symbol.iterator] or next). This may be because we accessed properties from anyType, + // or it may have led to an error inside getElementTypeOfIterable. + const forOfStatement = declaration.parent.parent; + return checkRightHandSideOfForOf(forOfStatement) || anyType; + } + + if (isBindingPattern(declaration.parent)) { + return getTypeForBindingElement(declaration as BindingElement); + } + + const isProperty = (isPropertyDeclaration(declaration) && !hasAccessorModifier(declaration)) || isPropertySignature(declaration) || isJSDocPropertyTag(declaration); + const isOptional = includeOptionality && isOptionalDeclaration(declaration); + + // Use type from type annotation if one is present + const declaredType = tryGetTypeFromEffectiveTypeNode(declaration); + if (isCatchClauseVariableDeclarationOrBindingElement(declaration)) { + if (declaredType) { + // If the catch clause is explicitly annotated with any or unknown, accept it, otherwise error. + return isTypeAny(declaredType) || declaredType === unknownType ? declaredType : errorType; + } + // If the catch clause is not explicitly annotated, treat it as though it were explicitly + // annotated with unknown or any, depending on useUnknownInCatchVariables. + return useUnknownInCatchVariables ? unknownType : anyType; + } + if (declaredType) { + return addOptionality(declaredType, isProperty, isOptional); + } + + if ( + (noImplicitAny || isInJSFile(declaration)) && + isVariableDeclaration(declaration) && !isBindingPattern(declaration.name) && + !(getCombinedModifierFlagsCached(declaration) & ModifierFlags.Export) && !(declaration.flags & NodeFlags.Ambient) + ) { + // If --noImplicitAny is on or the declaration is in a Javascript file, + // use control flow tracked 'any' type for non-ambient, non-exported var or let variables with no + // initializer or a 'null' or 'undefined' initializer. + if (!(getCombinedNodeFlagsCached(declaration) & NodeFlags.Constant) && (!declaration.initializer || isNullOrUndefined(declaration.initializer))) { + return autoType; + } + // Use control flow tracked 'any[]' type for non-ambient, non-exported variables with an empty array + // literal initializer. + if (declaration.initializer && isEmptyArrayLiteral(declaration.initializer)) { + return autoArrayType; + } + } + + if (isParameter(declaration)) { + if (!declaration.symbol) { + // parameters of function types defined in JSDoc in TS files don't have symbols + return; + } + const func = declaration.parent as FunctionLikeDeclaration; + // For a parameter of a set accessor, use the type of the get accessor if one is present + if (func.kind === SyntaxKind.SetAccessor && hasBindableName(func)) { + const getter = getDeclarationOfKind(getSymbolOfDeclaration(declaration.parent), SyntaxKind.GetAccessor); + if (getter) { + const getterSignature = getSignatureFromDeclaration(getter); + const thisParameter = getAccessorThisParameter(func as AccessorDeclaration); + if (thisParameter && declaration === thisParameter) { + // Use the type from the *getter* + Debug.assert(!thisParameter.type); + return getTypeOfSymbol(getterSignature.thisParameter!); + } + return getReturnTypeOfSignature(getterSignature); + } + } + const parameterTypeOfTypeTag = getParameterTypeOfTypeTag(func, declaration); + if (parameterTypeOfTypeTag) return parameterTypeOfTypeTag; + // Use contextual parameter type if one is available + const type = declaration.symbol.escapedName === InternalSymbolName.This ? getContextualThisParameterType(func) : getContextuallyTypedParameterType(declaration); + if (type) { + return addOptionality(type, /*isProperty*/ false, isOptional); + } + } + + // Use the type of the initializer expression if one is present and the declaration is + // not a parameter of a contextually typed function + if (hasOnlyExpressionInitializer(declaration) && !!declaration.initializer) { + if (isInJSFile(declaration) && !isParameter(declaration)) { + const containerObjectType = getJSContainerObjectType(declaration, getSymbolOfDeclaration(declaration), getDeclaredExpandoInitializer(declaration)); + if (containerObjectType) { + return containerObjectType; + } + } + const type = widenTypeInferredFromInitializer(declaration, checkDeclarationInitializer(declaration, checkMode)); + return addOptionality(type, isProperty, isOptional); + } + + if (isPropertyDeclaration(declaration) && (noImplicitAny || isInJSFile(declaration))) { + // We have a property declaration with no type annotation or initializer, in noImplicitAny mode or a .js file. + // Use control flow analysis of this.xxx assignments in the constructor or static block to determine the type of the property. + if (!hasStaticModifier(declaration)) { + const constructor = findConstructorDeclaration(declaration.parent); + const type = constructor ? getFlowTypeInConstructor(declaration.symbol, constructor) : + getEffectiveModifierFlags(declaration) & ModifierFlags.Ambient ? getTypeOfPropertyInBaseClass(declaration.symbol) : + undefined; + return type && addOptionality(type, /*isProperty*/ true, isOptional); + } + else { + const staticBlocks = filter(declaration.parent.members, isClassStaticBlockDeclaration); + const type = staticBlocks.length ? getFlowTypeInStaticBlocks(declaration.symbol, staticBlocks) : + getEffectiveModifierFlags(declaration) & ModifierFlags.Ambient ? getTypeOfPropertyInBaseClass(declaration.symbol) : + undefined; + return type && addOptionality(type, /*isProperty*/ true, isOptional); + } + } + + if (isJsxAttribute(declaration)) { + // if JSX attribute doesn't have initializer, by default the attribute will have boolean value of true. + // I.e is sugar for + return trueType; + } + + // If the declaration specifies a binding pattern and is not a parameter of a contextually + // typed function, use the type implied by the binding pattern + if (isBindingPattern(declaration.name)) { + return getTypeFromBindingPattern(declaration.name, /*includePatternInType*/ false, /*reportErrors*/ true); + } + + // No type specified and nothing can be inferred + return undefined; + } + + function isConstructorDeclaredProperty(symbol: Symbol) { + // A property is considered a constructor declared property when all declaration sites are this.xxx assignments, + // when no declaration sites have JSDoc type annotations, and when at least one declaration site is in the body of + // a class constructor. + if (symbol.valueDeclaration && isBinaryExpression(symbol.valueDeclaration)) { + const links = getSymbolLinks(symbol); + if (links.isConstructorDeclaredProperty === undefined) { + links.isConstructorDeclaredProperty = false; + links.isConstructorDeclaredProperty = !!getDeclaringConstructor(symbol) && every(symbol.declarations, declaration => + isBinaryExpression(declaration) && + isPossiblyAliasedThisProperty(declaration) && + (declaration.left.kind !== SyntaxKind.ElementAccessExpression || isStringOrNumericLiteralLike((declaration.left as ElementAccessExpression).argumentExpression)) && + !getAnnotatedTypeForAssignmentDeclaration(/*declaredType*/ undefined, declaration, symbol, declaration)); + } + return links.isConstructorDeclaredProperty; + } + return false; + } + + function isAutoTypedProperty(symbol: Symbol) { + // A property is auto-typed when its declaration has no type annotation or initializer and we're in + // noImplicitAny mode or a .js file. + const declaration = symbol.valueDeclaration; + return declaration && isPropertyDeclaration(declaration) && !getEffectiveTypeAnnotationNode(declaration) && + !declaration.initializer && (noImplicitAny || isInJSFile(declaration)); + } + + function getDeclaringConstructor(symbol: Symbol) { + if (!symbol.declarations) { + return; + } + for (const declaration of symbol.declarations) { + const container = getThisContainer(declaration, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (container && (container.kind === SyntaxKind.Constructor || isJSConstructor(container))) { + return container as ConstructorDeclaration; + } + } + } + + /** Create a synthetic property access flow node after the last statement of the file */ + function getFlowTypeFromCommonJSExport(symbol: Symbol) { + const file = getSourceFileOfNode(symbol.declarations![0]); + const accessName = unescapeLeadingUnderscores(symbol.escapedName); + const areAllModuleExports = symbol.declarations!.every(d => isInJSFile(d) && isAccessExpression(d) && isModuleExportsAccessExpression(d.expression)); + const reference = areAllModuleExports + ? factory.createPropertyAccessExpression(factory.createPropertyAccessExpression(factory.createIdentifier("module"), factory.createIdentifier("exports")), accessName) + : factory.createPropertyAccessExpression(factory.createIdentifier("exports"), accessName); + if (areAllModuleExports) { + setParent((reference.expression as PropertyAccessExpression).expression, reference.expression); + } + setParent(reference.expression, reference); + setParent(reference, file); + reference.flowNode = file.endFlowNode; + return getFlowTypeOfReference(reference, autoType, undefinedType); + } + + function getFlowTypeInStaticBlocks(symbol: Symbol, staticBlocks: readonly ClassStaticBlockDeclaration[]) { + const accessName = startsWith(symbol.escapedName as string, "__#") + ? factory.createPrivateIdentifier((symbol.escapedName as string).split("@")[1]) + : unescapeLeadingUnderscores(symbol.escapedName); + for (const staticBlock of staticBlocks) { + const reference = factory.createPropertyAccessExpression(factory.createThis(), accessName); + setParent(reference.expression, reference); + setParent(reference, staticBlock); + reference.flowNode = staticBlock.returnFlowNode; + const flowType = getFlowTypeOfProperty(reference, symbol); + if (noImplicitAny && (flowType === autoType || flowType === autoArrayType)) { + error(symbol.valueDeclaration, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); + } + // We don't infer a type if assignments are only null or undefined. + if (everyType(flowType, isNullableType)) { + continue; + } + return convertAutoToAny(flowType); + } + } + + function getFlowTypeInConstructor(symbol: Symbol, constructor: ConstructorDeclaration) { + const accessName = startsWith(symbol.escapedName as string, "__#") + ? factory.createPrivateIdentifier((symbol.escapedName as string).split("@")[1]) + : unescapeLeadingUnderscores(symbol.escapedName); + const reference = factory.createPropertyAccessExpression(factory.createThis(), accessName); + setParent(reference.expression, reference); + setParent(reference, constructor); + reference.flowNode = constructor.returnFlowNode; + const flowType = getFlowTypeOfProperty(reference, symbol); + if (noImplicitAny && (flowType === autoType || flowType === autoArrayType)) { + error(symbol.valueDeclaration, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); + } + // We don't infer a type if assignments are only null or undefined. + return everyType(flowType, isNullableType) ? undefined : convertAutoToAny(flowType); + } + + function getFlowTypeOfProperty(reference: Node, prop: Symbol | undefined) { + const initialType = prop?.valueDeclaration + && (!isAutoTypedProperty(prop) || getEffectiveModifierFlags(prop.valueDeclaration) & ModifierFlags.Ambient) + && getTypeOfPropertyInBaseClass(prop) + || undefinedType; + return getFlowTypeOfReference(reference, autoType, initialType); + } + + function getWidenedTypeForAssignmentDeclaration(symbol: Symbol, resolvedSymbol?: Symbol) { + // function/class/{} initializers are themselves containers, so they won't merge in the same way as other initializers + const container = getAssignedExpandoInitializer(symbol.valueDeclaration); + if (container) { + const tag = isInJSFile(container) ? getJSDocTypeTag(container) : undefined; + if (tag && tag.typeExpression) { + return getTypeFromTypeNode(tag.typeExpression); + } + const containerObjectType = symbol.valueDeclaration && getJSContainerObjectType(symbol.valueDeclaration, symbol, container); + return containerObjectType || getWidenedLiteralType(checkExpressionCached(container)); + } + let type; + let definedInConstructor = false; + let definedInMethod = false; + // We use control flow analysis to determine the type of the property if the property qualifies as a constructor + // declared property and the resulting control flow type isn't just undefined or null. + if (isConstructorDeclaredProperty(symbol)) { + type = getFlowTypeInConstructor(symbol, getDeclaringConstructor(symbol)!); + } + if (!type) { + let types: Type[] | undefined; + if (symbol.declarations) { + let jsdocType: Type | undefined; + for (const declaration of symbol.declarations) { + const expression = (isBinaryExpression(declaration) || isCallExpression(declaration)) ? declaration : + isAccessExpression(declaration) ? isBinaryExpression(declaration.parent) ? declaration.parent : declaration : + undefined; + if (!expression) { + continue; // Non-assignment declaration merged in (eg, an Identifier to mark the thing as a namespace) - skip over it and pull type info from elsewhere + } + + const kind = isAccessExpression(expression) + ? getAssignmentDeclarationPropertyAccessKind(expression) + : getAssignmentDeclarationKind(expression); + if (kind === AssignmentDeclarationKind.ThisProperty || isBinaryExpression(expression) && isPossiblyAliasedThisProperty(expression, kind)) { + if (isDeclarationInConstructor(expression)) { + definedInConstructor = true; + } + else { + definedInMethod = true; + } + } + if (!isCallExpression(expression)) { + jsdocType = getAnnotatedTypeForAssignmentDeclaration(jsdocType, expression, symbol, declaration); + } + if (!jsdocType) { + (types || (types = [])).push((isBinaryExpression(expression) || isCallExpression(expression)) ? getInitializerTypeFromAssignmentDeclaration(symbol, resolvedSymbol, expression, kind) : neverType); + } + } + type = jsdocType; + } + if (!type) { + if (!length(types)) { + return errorType; // No types from any declarations :( + } + let constructorTypes = definedInConstructor && symbol.declarations ? getConstructorDefinedThisAssignmentTypes(types!, symbol.declarations) : undefined; + // use only the constructor types unless they were only assigned null | undefined (including widening variants) + if (definedInMethod) { + const propType = getTypeOfPropertyInBaseClass(symbol); + if (propType) { + (constructorTypes || (constructorTypes = [])).push(propType); + definedInConstructor = true; + } + } + const sourceTypes = some(constructorTypes, t => !!(t.flags & ~TypeFlags.Nullable)) ? constructorTypes : types; // TODO: GH#18217 + type = getUnionType(sourceTypes!); + } + } + const widened = getWidenedType(addOptionality(type, /*isProperty*/ false, definedInMethod && !definedInConstructor)); + if (symbol.valueDeclaration && isInJSFile(symbol.valueDeclaration) && filterType(widened, t => !!(t.flags & ~TypeFlags.Nullable)) === neverType) { + reportImplicitAny(symbol.valueDeclaration, anyType); + return anyType; + } + return widened; + } + + function getJSContainerObjectType(decl: Node, symbol: Symbol, init: Expression | undefined): Type | undefined { + if (!isInJSFile(decl) || !init || !isObjectLiteralExpression(init) || init.properties.length) { + return undefined; + } + const exports = createSymbolTable(); + while (isBinaryExpression(decl) || isPropertyAccessExpression(decl)) { + const s = getSymbolOfNode(decl); + if (s?.exports?.size) { + mergeSymbolTable(exports, s.exports); + } + decl = isBinaryExpression(decl) ? decl.parent : decl.parent.parent; + } + const s = getSymbolOfNode(decl); + if (s?.exports?.size) { + mergeSymbolTable(exports, s.exports); + } + const type = createAnonymousType(symbol, exports, emptyArray, emptyArray, emptyArray); + type.objectFlags |= ObjectFlags.JSLiteral; + return type; + } + + function getAnnotatedTypeForAssignmentDeclaration(declaredType: Type | undefined, expression: Expression, symbol: Symbol, declaration: Declaration) { + const typeNode = getEffectiveTypeAnnotationNode(expression.parent); + if (typeNode) { + const type = getWidenedType(getTypeFromTypeNode(typeNode)); + if (!declaredType) { + return type; + } + else if (!isErrorType(declaredType) && !isErrorType(type) && !isTypeIdenticalTo(declaredType, type)) { + errorNextVariableOrPropertyDeclarationMustHaveSameType(/*firstDeclaration*/ undefined, declaredType, declaration, type); + } + } + if (symbol.parent?.valueDeclaration) { + const possiblyAnnotatedSymbol = getFunctionExpressionParentSymbolOrSymbol(symbol.parent); + if (possiblyAnnotatedSymbol.valueDeclaration) { + const typeNode = getEffectiveTypeAnnotationNode(possiblyAnnotatedSymbol.valueDeclaration); + if (typeNode) { + const annotationSymbol = getPropertyOfType(getTypeFromTypeNode(typeNode), symbol.escapedName); + if (annotationSymbol) { + return getNonMissingTypeOfSymbol(annotationSymbol); + } + } + } + } + + return declaredType; + } + + /** If we don't have an explicit JSDoc type, get the type from the initializer. */ + function getInitializerTypeFromAssignmentDeclaration(symbol: Symbol, resolvedSymbol: Symbol | undefined, expression: BinaryExpression | CallExpression, kind: AssignmentDeclarationKind) { + if (isCallExpression(expression)) { + if (resolvedSymbol) { + return getTypeOfSymbol(resolvedSymbol); // This shouldn't happen except under some hopefully forbidden merges of export assignments and object define assignments + } + const objectLitType = checkExpressionCached((expression as BindableObjectDefinePropertyCall).arguments[2]); + const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String); + if (valueType) { + return valueType; + } + const getFunc = getTypeOfPropertyOfType(objectLitType, "get" as __String); + if (getFunc) { + const getSig = getSingleCallSignature(getFunc); + if (getSig) { + return getReturnTypeOfSignature(getSig); + } + } + const setFunc = getTypeOfPropertyOfType(objectLitType, "set" as __String); + if (setFunc) { + const setSig = getSingleCallSignature(setFunc); + if (setSig) { + return getTypeOfFirstParameterOfSignature(setSig); + } + } + return anyType; + } + if (containsSameNamedThisProperty(expression.left, expression.right)) { + return anyType; + } + const isDirectExport = kind === AssignmentDeclarationKind.ExportsProperty && (isPropertyAccessExpression(expression.left) || isElementAccessExpression(expression.left)) && (isModuleExportsAccessExpression(expression.left.expression) || (isIdentifier(expression.left.expression) && isExportsIdentifier(expression.left.expression))); + const type = resolvedSymbol ? getTypeOfSymbol(resolvedSymbol) + : isDirectExport ? getRegularTypeOfLiteralType(checkExpressionCached(expression.right)) + : getWidenedLiteralType(checkExpressionCached(expression.right)); + if ( + type.flags & TypeFlags.Object && + kind === AssignmentDeclarationKind.ModuleExports && + symbol.escapedName === InternalSymbolName.ExportEquals + ) { + const exportedType = resolveStructuredTypeMembers(type as ObjectType); + const members = createSymbolTable(); + copyEntries(exportedType.members, members); + const initialSize = members.size; + if (resolvedSymbol && !resolvedSymbol.exports) { + resolvedSymbol.exports = createSymbolTable(); + } + (resolvedSymbol || symbol).exports!.forEach((s, name) => { + const exportedMember = members.get(name)!; + if (exportedMember && exportedMember !== s && !(s.flags & SymbolFlags.Alias)) { + if (s.flags & SymbolFlags.Value && exportedMember.flags & SymbolFlags.Value) { + // If the member has an additional value-like declaration, union the types from the two declarations, + // but issue an error if they occurred in two different files. The purpose is to support a JS file with + // a pattern like: + // + // module.exports = { a: true }; + // module.exports.a = 3; + // + // but we may have a JS file with `module.exports = { a: true }` along with a TypeScript module augmentation + // declaring an `export const a: number`. In that case, we issue a duplicate identifier error, because + // it's unclear what that's supposed to mean, so it's probably a mistake. + if (s.valueDeclaration && exportedMember.valueDeclaration && getSourceFileOfNode(s.valueDeclaration) !== getSourceFileOfNode(exportedMember.valueDeclaration)) { + const unescapedName = unescapeLeadingUnderscores(s.escapedName); + const exportedMemberName = tryCast(exportedMember.valueDeclaration, isNamedDeclaration)?.name || exportedMember.valueDeclaration; + addRelatedInfo( + error(s.valueDeclaration, Diagnostics.Duplicate_identifier_0, unescapedName), + createDiagnosticForNode(exportedMemberName, Diagnostics._0_was_also_declared_here, unescapedName), + ); + addRelatedInfo( + error(exportedMemberName, Diagnostics.Duplicate_identifier_0, unescapedName), + createDiagnosticForNode(s.valueDeclaration, Diagnostics._0_was_also_declared_here, unescapedName), + ); + } + const union = createSymbol(s.flags | exportedMember.flags, name); + union.links.type = getUnionType([getTypeOfSymbol(s), getTypeOfSymbol(exportedMember)]); + union.valueDeclaration = exportedMember.valueDeclaration; + union.declarations = concatenate(exportedMember.declarations, s.declarations); + members.set(name, union); + } + else { + members.set(name, mergeSymbol(s, exportedMember)); + } + } + else { + members.set(name, s); + } + }); + const result = createAnonymousType( + initialSize !== members.size ? undefined : exportedType.symbol, // Only set the type's symbol if it looks to be the same as the original type + members, + exportedType.callSignatures, + exportedType.constructSignatures, + exportedType.indexInfos, + ); + if (initialSize === members.size) { + if (type.aliasSymbol) { + result.aliasSymbol = type.aliasSymbol; + result.aliasTypeArguments = type.aliasTypeArguments; + } + if (getObjectFlags(type) & ObjectFlags.Reference) { + result.aliasSymbol = (type as TypeReference).symbol; + const args = getTypeArguments(type as TypeReference); + result.aliasTypeArguments = length(args) ? args : undefined; + } + } + result.objectFlags |= getPropagatingFlagsOfTypes([type]) | getObjectFlags(type) & (ObjectFlags.JSLiteral | ObjectFlags.ArrayLiteral | ObjectFlags.ObjectLiteral); + if (result.symbol && result.symbol.flags & SymbolFlags.Class && type === getDeclaredTypeOfClassOrInterface(result.symbol)) { + result.objectFlags |= ObjectFlags.IsClassInstanceClone; // Propagate the knowledge that this type is equivalent to the symbol's class instance type + } + return result; + } + if (isEmptyArrayLiteralType(type)) { + reportImplicitAny(expression, anyArrayType); + return anyArrayType; + } + return type; + } + + function containsSameNamedThisProperty(thisProperty: Expression, expression: Expression) { + return isPropertyAccessExpression(thisProperty) + && thisProperty.expression.kind === SyntaxKind.ThisKeyword + && forEachChildRecursively(expression, n => isMatchingReference(thisProperty, n)); + } + + function isDeclarationInConstructor(expression: Expression) { + const thisContainer = getThisContainer(expression, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + // Properties defined in a constructor (or base constructor, or javascript constructor function) don't get undefined added. + // Function expressions that are assigned to the prototype count as methods. + return thisContainer.kind === SyntaxKind.Constructor || + thisContainer.kind === SyntaxKind.FunctionDeclaration || + (thisContainer.kind === SyntaxKind.FunctionExpression && !isPrototypePropertyAssignment(thisContainer.parent)); + } + + function getConstructorDefinedThisAssignmentTypes(types: Type[], declarations: Declaration[]): Type[] | undefined { + Debug.assert(types.length === declarations.length); + return types.filter((_, i) => { + const declaration = declarations[i]; + const expression = isBinaryExpression(declaration) ? declaration : + isBinaryExpression(declaration.parent) ? declaration.parent : undefined; + return expression && isDeclarationInConstructor(expression); + }); + } + + // Return the type implied by a binding pattern element. This is the type of the initializer of the element if + // one is present. Otherwise, if the element is itself a binding pattern, it is the type implied by the binding + // pattern. Otherwise, it is the type any. + function getTypeFromBindingElement(element: BindingElement, includePatternInType?: boolean, reportErrors?: boolean): Type { + if (element.initializer) { + // The type implied by a binding pattern is independent of context, so we check the initializer with no + // contextual type or, if the element itself is a binding pattern, with the type implied by that binding + // pattern. + const contextualType = isBindingPattern(element.name) ? getTypeFromBindingPattern(element.name, /*includePatternInType*/ true, /*reportErrors*/ false) : unknownType; + return addOptionality(widenTypeInferredFromInitializer(element, checkDeclarationInitializer(element, reportErrors ? CheckMode.Normal : CheckMode.Contextual, contextualType))); + } + if (isBindingPattern(element.name)) { + return getTypeFromBindingPattern(element.name, includePatternInType, reportErrors); + } + if (reportErrors && !declarationBelongsToPrivateAmbientMember(element)) { + reportImplicitAny(element, anyType); + } + // When we're including the pattern in the type (an indication we're obtaining a contextual type), we + // use a non-inferrable any type. Inference will never directly infer this type, but it is possible + // to infer a type that contains it, e.g. for a binding pattern like [foo] or { foo }. In such cases, + // widening of the binding pattern type substitutes a regular any for the non-inferrable any. + return includePatternInType ? nonInferrableAnyType : anyType; + } + + // Return the type implied by an object binding pattern + function getTypeFromObjectBindingPattern(pattern: ObjectBindingPattern, includePatternInType: boolean, reportErrors: boolean): Type { + const members = createSymbolTable(); + let stringIndexInfo: IndexInfo | undefined; + let objectFlags = ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + forEach(pattern.elements, e => { + const name = e.propertyName || e.name as Identifier; + if (e.dotDotDotToken) { + stringIndexInfo = createIndexInfo(stringType, anyType, /*isReadonly*/ false); + return; + } + + const exprType = getLiteralTypeFromPropertyName(name); + if (!isTypeUsableAsPropertyName(exprType)) { + // do not include computed properties in the implied type + objectFlags |= ObjectFlags.ObjectLiteralPatternWithComputedProperties; + return; + } + const text = getPropertyNameFromType(exprType); + const flags = SymbolFlags.Property | (e.initializer ? SymbolFlags.Optional : 0); + const symbol = createSymbol(flags, text); + symbol.links.type = getTypeFromBindingElement(e, includePatternInType, reportErrors); + symbol.links.bindingElement = e; + members.set(symbol.escapedName, symbol); + }); + const result = createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, stringIndexInfo ? [stringIndexInfo] : emptyArray); + result.objectFlags |= objectFlags; + if (includePatternInType) { + result.pattern = pattern; + result.objectFlags |= ObjectFlags.ContainsObjectOrArrayLiteral; + } + return result; + } + + // Return the type implied by an array binding pattern + function getTypeFromArrayBindingPattern(pattern: BindingPattern, includePatternInType: boolean, reportErrors: boolean): Type { + const elements = pattern.elements; + const lastElement = lastOrUndefined(elements); + const restElement = lastElement && lastElement.kind === SyntaxKind.BindingElement && lastElement.dotDotDotToken ? lastElement : undefined; + if (elements.length === 0 || elements.length === 1 && restElement) { + return languageVersion >= ScriptTarget.ES2015 ? createIterableType(anyType) : anyArrayType; + } + const elementTypes = map(elements, e => isOmittedExpression(e) ? anyType : getTypeFromBindingElement(e, includePatternInType, reportErrors)); + const minLength = findLastIndex(elements, e => !(e === restElement || isOmittedExpression(e) || hasDefaultValue(e)), elements.length - 1) + 1; + const elementFlags = map(elements, (e, i) => e === restElement ? ElementFlags.Rest : i >= minLength ? ElementFlags.Optional : ElementFlags.Required); + let result = createTupleType(elementTypes, elementFlags) as TypeReference; + if (includePatternInType) { + result = cloneTypeReference(result); + result.pattern = pattern; + result.objectFlags |= ObjectFlags.ContainsObjectOrArrayLiteral; + } + return result; + } + + // Return the type implied by a binding pattern. This is the type implied purely by the binding pattern itself + // and without regard to its context (i.e. without regard any type annotation or initializer associated with the + // declaration in which the binding pattern is contained). For example, the implied type of [x, y] is [any, any] + // and the implied type of { x, y: z = 1 } is { x: any; y: number; }. The type implied by a binding pattern is + // used as the contextual type of an initializer associated with the binding pattern. Also, for a destructuring + // parameter with no type annotation or initializer, the type implied by the binding pattern becomes the type of + // the parameter. + function getTypeFromBindingPattern(pattern: BindingPattern, includePatternInType = false, reportErrors = false): Type { + return pattern.kind === SyntaxKind.ObjectBindingPattern + ? getTypeFromObjectBindingPattern(pattern, includePatternInType, reportErrors) + : getTypeFromArrayBindingPattern(pattern, includePatternInType, reportErrors); + } + + // Return the type associated with a variable, parameter, or property declaration. In the simple case this is the type + // specified in a type annotation or inferred from an initializer. However, in the case of a destructuring declaration it + // is a bit more involved. For example: + // + // var [x, s = ""] = [1, "one"]; + // + // Here, the array literal [1, "one"] is contextually typed by the type [any, string], which is the implied type of the + // binding pattern [x, s = ""]. Because the contextual type is a tuple type, the resulting type of [1, "one"] is the + // tuple type [number, string]. Thus, the type inferred for 'x' is number and the type inferred for 's' is string. + function getWidenedTypeForVariableLikeDeclaration(declaration: ParameterDeclaration | PropertyDeclaration | PropertySignature | VariableDeclaration | BindingElement | JSDocPropertyLikeTag, reportErrors?: boolean): Type { + return widenTypeForVariableLikeDeclaration(getTypeForVariableLikeDeclaration(declaration, /*includeOptionality*/ true, CheckMode.Normal), declaration, reportErrors); + } + + function getTypeFromImportAttributes(node: ImportAttributes): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const symbol = createSymbol(SymbolFlags.ObjectLiteral, InternalSymbolName.ImportAttributes); + const members = createSymbolTable(); + forEach(node.elements, attr => { + const member = createSymbol(SymbolFlags.Property, getNameFromImportAttribute(attr)); + member.parent = symbol; + member.links.type = checkImportAttribute(attr); + member.links.target = member; + members.set(member.escapedName, member); + }); + const type = createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + type.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.NonInferrableType; + links.resolvedType = type; + } + return links.resolvedType; + } + + function isGlobalSymbolConstructor(node: Node) { + const symbol = getSymbolOfNode(node); + const globalSymbol = getGlobalESSymbolConstructorTypeSymbol(/*reportErrors*/ false); + return globalSymbol && symbol && symbol === globalSymbol; + } + + function widenTypeForVariableLikeDeclaration(type: Type | undefined, declaration: any, reportErrors?: boolean) { + if (type) { + // TODO: If back compat with pre-3.0/4.0 libs isn't required, remove the following SymbolConstructor special case transforming `symbol` into `unique symbol` + if (type.flags & TypeFlags.ESSymbol && isGlobalSymbolConstructor(declaration.parent)) { + type = getESSymbolLikeTypeForNode(declaration); + } + if (reportErrors) { + reportErrorsFromWidening(declaration, type); + } + + // always widen a 'unique symbol' type if the type was created for a different declaration. + if (type.flags & TypeFlags.UniqueESSymbol && (isBindingElement(declaration) || !declaration.type) && type.symbol !== getSymbolOfDeclaration(declaration)) { + type = esSymbolType; + } + + return getWidenedType(type); + } + + // Rest parameters default to type any[], other parameters default to type any + type = isParameter(declaration) && declaration.dotDotDotToken ? anyArrayType : anyType; + + // Report implicit any errors unless this is a private property within an ambient declaration + if (reportErrors) { + if (!declarationBelongsToPrivateAmbientMember(declaration)) { + reportImplicitAny(declaration, type); + } + } + return type; + } + + function declarationBelongsToPrivateAmbientMember(declaration: VariableLikeDeclaration) { + const root = getRootDeclaration(declaration); + const memberDeclaration = root.kind === SyntaxKind.Parameter ? root.parent : root; + return isPrivateWithinAmbient(memberDeclaration); + } + + function tryGetTypeFromEffectiveTypeNode(node: Node) { + const typeNode = getEffectiveTypeAnnotationNode(node); + if (typeNode) { + return getTypeFromTypeNode(typeNode); + } + } + + function isParameterOfContextSensitiveSignature(symbol: Symbol) { + let decl = symbol.valueDeclaration; + if (!decl) { + return false; + } + if (isBindingElement(decl)) { + decl = walkUpBindingElementsAndPatterns(decl); + } + if (isParameter(decl)) { + return isContextSensitiveFunctionOrObjectLiteralMethod(decl.parent); + } + return false; + } + + function getTypeOfVariableOrParameterOrProperty(symbol: Symbol, checkMode?: CheckMode): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + const type = getTypeOfVariableOrParameterOrPropertyWorker(symbol, checkMode); + // For a contextually typed parameter it is possible that a type has already + // been assigned (in assignTypeToParameterAndFixTypeParameters), and we want + // to preserve this type. In fact, we need to _prefer_ that type, but it won't + // be assigned until contextual typing is complete, so we need to defer in + // cases where contextual typing may take place. + if (!links.type && !isParameterOfContextSensitiveSignature(symbol) && !checkMode) { + links.type = type; + } + return type; + } + return links.type; + } + + function getTypeOfVariableOrParameterOrPropertyWorker(symbol: Symbol, checkMode?: CheckMode): Type { + // Handle prototype property + if (symbol.flags & SymbolFlags.Prototype) { + return getTypeOfPrototypeProperty(symbol); + } + // CommonsJS require and module both have type any. + if (symbol === requireSymbol) { + return anyType; + } + if (symbol.flags & SymbolFlags.ModuleExports && symbol.valueDeclaration) { + const fileSymbol = getSymbolOfDeclaration(getSourceFileOfNode(symbol.valueDeclaration)); + const result = createSymbol(fileSymbol.flags, "exports" as __String); + result.declarations = fileSymbol.declarations ? fileSymbol.declarations.slice() : []; + result.parent = symbol; + result.links.target = fileSymbol; + if (fileSymbol.valueDeclaration) result.valueDeclaration = fileSymbol.valueDeclaration; + if (fileSymbol.members) result.members = new Map(fileSymbol.members); + if (fileSymbol.exports) result.exports = new Map(fileSymbol.exports); + const members = createSymbolTable(); + members.set("exports" as __String, result); + return createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + } + Debug.assertIsDefined(symbol.valueDeclaration); + const declaration = symbol.valueDeclaration; + // Handle export default expressions + if (isSourceFile(declaration) && isJsonSourceFile(declaration)) { + if (!declaration.statements.length) { + return emptyObjectType; + } + return getWidenedType(getWidenedLiteralType(checkExpression(declaration.statements[0].expression))); + } + if (isAccessor(declaration)) { + // Binding of certain patterns in JS code will occasionally mark symbols as both properties + // and accessors. Here we dispatch to accessor resolution if needed. + return getTypeOfAccessors(symbol); + } + + // Handle variable, parameter or property + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` + if (symbol.flags & SymbolFlags.ValueModule && !(symbol.flags & SymbolFlags.Assignment)) { + return getTypeOfFuncClassEnumModule(symbol); + } + + // When trying to get the *contextual* type of a binding element, it's possible to fall in a loop and therefore + // end up in a circularity-like situation. This is not a true circularity so we should not report such an error. + // For example, here the looping could happen when trying to get the type of `a` (binding element): + // + // const { a, b = a } = { a: 0 } + // + if (isBindingElement(declaration) && checkMode === CheckMode.Contextual) { + return errorType; + } + return reportCircularityError(symbol); + } + let type: Type; + if (declaration.kind === SyntaxKind.ExportAssignment) { + type = widenTypeForVariableLikeDeclaration(tryGetTypeFromEffectiveTypeNode(declaration) || checkExpressionCached((declaration as ExportAssignment).expression), declaration); + } + else if ( + isBinaryExpression(declaration) || + (isInJSFile(declaration) && + (isCallExpression(declaration) || (isPropertyAccessExpression(declaration) || isBindableStaticElementAccessExpression(declaration)) && isBinaryExpression(declaration.parent))) + ) { + type = getWidenedTypeForAssignmentDeclaration(symbol); + } + else if ( + isPropertyAccessExpression(declaration) + || isElementAccessExpression(declaration) + || isIdentifier(declaration) + || isStringLiteralLike(declaration) + || isNumericLiteral(declaration) + || isClassDeclaration(declaration) + || isFunctionDeclaration(declaration) + || (isMethodDeclaration(declaration) && !isObjectLiteralMethod(declaration)) + || isMethodSignature(declaration) + || isSourceFile(declaration) + ) { + // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.Enum | SymbolFlags.ValueModule)) { + return getTypeOfFuncClassEnumModule(symbol); + } + type = isBinaryExpression(declaration.parent) ? + getWidenedTypeForAssignmentDeclaration(symbol) : + tryGetTypeFromEffectiveTypeNode(declaration) || anyType; + } + else if (isPropertyAssignment(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkPropertyAssignment(declaration); + } + else if (isJsxAttribute(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkJsxAttribute(declaration); + } + else if (isShorthandPropertyAssignment(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkExpressionForMutableLocation(declaration.name, CheckMode.Normal); + } + else if (isObjectLiteralMethod(declaration)) { + type = tryGetTypeFromEffectiveTypeNode(declaration) || checkObjectLiteralMethod(declaration, CheckMode.Normal); + } + else if ( + isParameter(declaration) + || isPropertyDeclaration(declaration) + || isPropertySignature(declaration) + || isVariableDeclaration(declaration) + || isBindingElement(declaration) + || isJSDocPropertyLikeTag(declaration) + ) { + type = getWidenedTypeForVariableLikeDeclaration(declaration, /*reportErrors*/ true); + } + // getTypeOfSymbol dispatches some JS merges incorrectly because their symbol flags are not mutually exclusive. + // Re-dispatch based on valueDeclaration.kind instead. + else if (isEnumDeclaration(declaration)) { + type = getTypeOfFuncClassEnumModule(symbol); + } + else if (isEnumMember(declaration)) { + type = getTypeOfEnumMember(symbol); + } + else { + return Debug.fail("Unhandled declaration kind! " + Debug.formatSyntaxKind(declaration.kind) + " for " + Debug.formatSymbol(symbol)); + } + + if (!popTypeResolution()) { + // Symbol is property of some kind that is merged with something - should use `getTypeOfFuncClassEnumModule` and not `getTypeOfVariableOrParameterOrProperty` + if (symbol.flags & SymbolFlags.ValueModule && !(symbol.flags & SymbolFlags.Assignment)) { + return getTypeOfFuncClassEnumModule(symbol); + } + + // When trying to get the *contextual* type of a binding element, it's possible to fall in a loop and therefore + // end up in a circularity-like situation. This is not a true circularity so we should not report such an error. + // For example, here the looping could happen when trying to get the type of `a` (binding element): + // + // const { a, b = a } = { a: 0 } + // + if (isBindingElement(declaration) && checkMode === CheckMode.Contextual) { + return type; + } + return reportCircularityError(symbol); + } + return type; + } + + function getAnnotatedAccessorTypeNode(accessor: AccessorDeclaration | PropertyDeclaration | undefined): TypeNode | undefined { + if (accessor) { + switch (accessor.kind) { + case SyntaxKind.GetAccessor: + const getterTypeAnnotation = getEffectiveReturnTypeNode(accessor); + return getterTypeAnnotation; + case SyntaxKind.SetAccessor: + const setterTypeAnnotation = getEffectiveSetAccessorTypeAnnotationNode(accessor); + return setterTypeAnnotation; + case SyntaxKind.PropertyDeclaration: + Debug.assert(hasAccessorModifier(accessor)); + const accessorTypeAnnotation = getEffectiveTypeAnnotationNode(accessor); + return accessorTypeAnnotation; + } + } + return undefined; + } + + function getAnnotatedAccessorType(accessor: AccessorDeclaration | PropertyDeclaration | undefined): Type | undefined { + const node = getAnnotatedAccessorTypeNode(accessor); + return node && getTypeFromTypeNode(node); + } + + function getAnnotatedAccessorThisParameter(accessor: AccessorDeclaration): Symbol | undefined { + const parameter = getAccessorThisParameter(accessor); + return parameter && parameter.symbol; + } + + function getThisTypeOfDeclaration(declaration: SignatureDeclaration): Type | undefined { + return getThisTypeOfSignature(getSignatureFromDeclaration(declaration)); + } + + function getTypeOfAccessors(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + return errorType; + } + const getter = getDeclarationOfKind(symbol, SyntaxKind.GetAccessor); + const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor); + const accessor = tryCast(getDeclarationOfKind(symbol, SyntaxKind.PropertyDeclaration), isAutoAccessorPropertyDeclaration); + + // We try to resolve a getter type annotation, a setter type annotation, or a getter function + // body return type inference, in that order. + let type = getter && isInJSFile(getter) && getTypeForDeclarationFromJSDocComment(getter) || + getAnnotatedAccessorType(getter) || + getAnnotatedAccessorType(setter) || + getAnnotatedAccessorType(accessor) || + getter && getter.body && getReturnTypeFromBody(getter) || + accessor && accessor.initializer && getWidenedTypeForVariableLikeDeclaration(accessor, /*reportErrors*/ true); + if (!type) { + if (setter && !isPrivateWithinAmbient(setter)) { + errorOrSuggestion(noImplicitAny, setter, Diagnostics.Property_0_implicitly_has_type_any_because_its_set_accessor_lacks_a_parameter_type_annotation, symbolToString(symbol)); + } + else if (getter && !isPrivateWithinAmbient(getter)) { + errorOrSuggestion(noImplicitAny, getter, Diagnostics.Property_0_implicitly_has_type_any_because_its_get_accessor_lacks_a_return_type_annotation, symbolToString(symbol)); + } + else if (accessor && !isPrivateWithinAmbient(accessor)) { + errorOrSuggestion(noImplicitAny, accessor, Diagnostics.Member_0_implicitly_has_an_1_type, symbolToString(symbol), "any"); + } + type = anyType; + } + if (!popTypeResolution()) { + if (getAnnotatedAccessorTypeNode(getter)) { + error(getter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + else if (getAnnotatedAccessorTypeNode(setter)) { + error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + else if (getAnnotatedAccessorTypeNode(accessor)) { + error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + else if (getter && noImplicitAny) { + error(getter, Diagnostics._0_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions, symbolToString(symbol)); + } + type = anyType; + } + links.type ??= type; + } + return links.type; + } + + function getWriteTypeOfAccessors(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.writeType) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.WriteType)) { + return errorType; + } + + const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor) + ?? tryCast(getDeclarationOfKind(symbol, SyntaxKind.PropertyDeclaration), isAutoAccessorPropertyDeclaration); + let writeType = getAnnotatedAccessorType(setter); + if (!popTypeResolution()) { + if (getAnnotatedAccessorTypeNode(setter)) { + error(setter, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + } + writeType = anyType; + } + // Absent an explicit setter type annotation we use the read type of the accessor. + links.writeType ??= writeType || getTypeOfAccessors(symbol); + } + return links.writeType; + } + + function getBaseTypeVariableOfClass(symbol: Symbol) { + const baseConstructorType = getBaseConstructorTypeOfClass(getDeclaredTypeOfClassOrInterface(symbol)); + return baseConstructorType.flags & TypeFlags.TypeVariable ? baseConstructorType : + baseConstructorType.flags & TypeFlags.Intersection ? find((baseConstructorType as IntersectionType).types, t => !!(t.flags & TypeFlags.TypeVariable)) : + undefined; + } + + function getTypeOfFuncClassEnumModule(symbol: Symbol): Type { + let links = getSymbolLinks(symbol); + const originalLinks = links; + if (!links.type) { + const expando = symbol.valueDeclaration && getSymbolOfExpando(symbol.valueDeclaration, /*allowDeclaration*/ false); + if (expando) { + const merged = mergeJSSymbols(symbol, expando); + if (merged) { + // note:we overwrite links because we just cloned the symbol + symbol = merged; + links = merged.links; + } + } + originalLinks.type = links.type = getTypeOfFuncClassEnumModuleWorker(symbol); + } + return links.type; + } + + function getTypeOfFuncClassEnumModuleWorker(symbol: Symbol): Type { + const declaration = symbol.valueDeclaration; + if (symbol.flags & SymbolFlags.Module && isShorthandAmbientModuleSymbol(symbol)) { + return anyType; + } + else if ( + declaration && (declaration.kind === SyntaxKind.BinaryExpression || + isAccessExpression(declaration) && + declaration.parent.kind === SyntaxKind.BinaryExpression) + ) { + return getWidenedTypeForAssignmentDeclaration(symbol); + } + else if (symbol.flags & SymbolFlags.ValueModule && declaration && isSourceFile(declaration) && declaration.commonJsModuleIndicator) { + const resolvedModule = resolveExternalModuleSymbol(symbol); + if (resolvedModule !== symbol) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + return errorType; + } + const exportEquals = getMergedSymbol(symbol.exports!.get(InternalSymbolName.ExportEquals)!); + const type = getWidenedTypeForAssignmentDeclaration(exportEquals, exportEquals === resolvedModule ? undefined : resolvedModule); + if (!popTypeResolution()) { + return reportCircularityError(symbol); + } + return type; + } + } + const type = createObjectType(ObjectFlags.Anonymous, symbol); + if (symbol.flags & SymbolFlags.Class) { + const baseTypeVariable = getBaseTypeVariableOfClass(symbol); + return baseTypeVariable ? getIntersectionType([type, baseTypeVariable]) : type; + } + else { + return strictNullChecks && symbol.flags & SymbolFlags.Optional ? getOptionalType(type, /*isProperty*/ true) : type; + } + } + + function getTypeOfEnumMember(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.type || (links.type = getDeclaredTypeOfEnumMember(symbol)); + } + + function getTypeOfAlias(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + return errorType; + } + const targetSymbol = resolveAlias(symbol); + const exportSymbol = symbol.declarations && getTargetOfAliasDeclaration(getDeclarationOfAliasSymbol(symbol)!, /*dontRecursivelyResolve*/ true); + const declaredType = firstDefined(exportSymbol?.declarations, d => isExportAssignment(d) ? tryGetTypeFromEffectiveTypeNode(d) : undefined); + + // It only makes sense to get the type of a value symbol. If the result of resolving + // the alias is not a value, then it has no type. To get the type associated with a + // type symbol, call getDeclaredTypeOfSymbol. + // This check is important because without it, a call to getTypeOfSymbol could end + // up recursively calling getTypeOfAlias, causing a stack overflow. + links.type ??= exportSymbol?.declarations && isDuplicatedCommonJSExport(exportSymbol.declarations) && symbol.declarations!.length ? getFlowTypeFromCommonJSExport(exportSymbol) + : isDuplicatedCommonJSExport(symbol.declarations) ? autoType + : declaredType ? declaredType + : getSymbolFlags(targetSymbol) & SymbolFlags.Value ? getTypeOfSymbol(targetSymbol) + : errorType; + + if (!popTypeResolution()) { + reportCircularityError(exportSymbol ?? symbol); + return links.type ??= errorType; + } + } + return links.type; + } + + function getTypeOfInstantiatedSymbol(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.type || (links.type = instantiateType(getTypeOfSymbol(links.target!), links.mapper)); + } + + function getWriteTypeOfInstantiatedSymbol(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.writeType || (links.writeType = instantiateType(getWriteTypeOfSymbol(links.target!), links.mapper)); + } + + function reportCircularityError(symbol: Symbol) { + const declaration = symbol.valueDeclaration; + // Check if variable has type annotation that circularly references the variable itself + if (declaration) { + if (getEffectiveTypeAnnotationNode(declaration)) { + error(symbol.valueDeclaration, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_type_annotation, symbolToString(symbol)); + return errorType; + } + // Check if variable has initializer that circularly references the variable itself + if (noImplicitAny && (declaration.kind !== SyntaxKind.Parameter || (declaration as HasInitializer).initializer)) { + error(symbol.valueDeclaration, Diagnostics._0_implicitly_has_type_any_because_it_does_not_have_a_type_annotation_and_is_referenced_directly_or_indirectly_in_its_own_initializer, symbolToString(symbol)); + } + } + else if (symbol.flags & SymbolFlags.Alias) { + const node = getDeclarationOfAliasSymbol(symbol); + if (node) { + error(node, Diagnostics.Circular_definition_of_import_alias_0, symbolToString(symbol)); + } + } + // Circularities could also result from parameters in function expressions that end up + // having themselves as contextual types following type argument inference. In those cases + // we have already reported an implicit any error so we don't report anything here. + return anyType; + } + + function getTypeOfSymbolWithDeferredType(symbol: Symbol) { + const links = getSymbolLinks(symbol); + if (!links.type) { + Debug.assertIsDefined(links.deferralParent); + Debug.assertIsDefined(links.deferralConstituents); + links.type = links.deferralParent.flags & TypeFlags.Union ? getUnionType(links.deferralConstituents) : getIntersectionType(links.deferralConstituents); + } + return links.type; + } + + function getWriteTypeOfSymbolWithDeferredType(symbol: Symbol): Type | undefined { + const links = getSymbolLinks(symbol); + if (!links.writeType && links.deferralWriteConstituents) { + Debug.assertIsDefined(links.deferralParent); + Debug.assertIsDefined(links.deferralConstituents); + links.writeType = links.deferralParent.flags & TypeFlags.Union ? getUnionType(links.deferralWriteConstituents) : getIntersectionType(links.deferralWriteConstituents); + } + return links.writeType; + } + + /** + * Distinct write types come only from set accessors, but synthetic union and intersection + * properties deriving from set accessors will either pre-compute or defer the union or + * intersection of the writeTypes of their constituents. + */ + function getWriteTypeOfSymbol(symbol: Symbol): Type { + const checkFlags = getCheckFlags(symbol); + if (symbol.flags & SymbolFlags.Property) { + return checkFlags & CheckFlags.SyntheticProperty ? + checkFlags & CheckFlags.DeferredType ? + getWriteTypeOfSymbolWithDeferredType(symbol) || getTypeOfSymbolWithDeferredType(symbol) : + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.SyntheticProperty + (symbol as TransientSymbol).links.writeType || (symbol as TransientSymbol).links.type! : + removeMissingType(getTypeOfSymbol(symbol), !!(symbol.flags & SymbolFlags.Optional)); + } + if (symbol.flags & SymbolFlags.Accessor) { + return checkFlags & CheckFlags.Instantiated ? + getWriteTypeOfInstantiatedSymbol(symbol) : + getWriteTypeOfAccessors(symbol); + } + return getTypeOfSymbol(symbol); + } + + function getTypeOfSymbol(symbol: Symbol, checkMode?: CheckMode): Type { + const checkFlags = getCheckFlags(symbol); + if (checkFlags & CheckFlags.DeferredType) { + return getTypeOfSymbolWithDeferredType(symbol); + } + if (checkFlags & CheckFlags.Instantiated) { + return getTypeOfInstantiatedSymbol(symbol); + } + if (checkFlags & CheckFlags.Mapped) { + return getTypeOfMappedSymbol(symbol as MappedSymbol); + } + if (checkFlags & CheckFlags.ReverseMapped) { + return getTypeOfReverseMappedSymbol(symbol as ReverseMappedSymbol); + } + if (symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property)) { + return getTypeOfVariableOrParameterOrProperty(symbol, checkMode); + } + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.Enum | SymbolFlags.ValueModule)) { + return getTypeOfFuncClassEnumModule(symbol); + } + if (symbol.flags & SymbolFlags.EnumMember) { + return getTypeOfEnumMember(symbol); + } + if (symbol.flags & SymbolFlags.Accessor) { + return getTypeOfAccessors(symbol); + } + if (symbol.flags & SymbolFlags.Alias) { + return getTypeOfAlias(symbol); + } + return errorType; + } + + function getNonMissingTypeOfSymbol(symbol: Symbol) { + return removeMissingType(getTypeOfSymbol(symbol), !!(symbol.flags & SymbolFlags.Optional)); + } + + function isReferenceToType(type: Type, target: Type) { + return type !== undefined + && target !== undefined + && (getObjectFlags(type) & ObjectFlags.Reference) !== 0 + && (type as TypeReference).target === target; + } + + function getTargetType(type: Type): Type { + return getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).target : type; + } + + // TODO: GH#18217 If `checkBase` is undefined, we should not call this because this will always return false. + function hasBaseType(type: Type, checkBase: Type | undefined) { + return check(type); + function check(type: Type): boolean { + if (getObjectFlags(type) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference)) { + const target = getTargetType(type) as InterfaceType; + return target === checkBase || some(getBaseTypes(target), check); + } + else if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, check); + } + return false; + } + } + + // Appends the type parameters given by a list of declarations to a set of type parameters and returns the resulting set. + // The function allocates a new array if the input type parameter set is undefined, but otherwise it modifies the set + // in-place and returns the same array. + function appendTypeParameters(typeParameters: TypeParameter[] | undefined, declarations: readonly TypeParameterDeclaration[]): TypeParameter[] | undefined { + for (const declaration of declarations) { + typeParameters = appendIfUnique(typeParameters, getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(declaration))); + } + return typeParameters; + } + + // Return the outer type parameters of a node or undefined if the node has no outer type parameters. + function getOuterTypeParameters(node: Node, includeThisTypes?: boolean): TypeParameter[] | undefined { + while (true) { + node = node.parent; // TODO: GH#18217 Use SourceFile kind check instead + if (node && isBinaryExpression(node)) { + // prototype assignments get the outer type parameters of their constructor function + const assignmentKind = getAssignmentDeclarationKind(node); + if (assignmentKind === AssignmentDeclarationKind.Prototype || assignmentKind === AssignmentDeclarationKind.PrototypeProperty) { + const symbol = getSymbolOfDeclaration(node.left as BindableStaticNameExpression | PropertyAssignment); + if (symbol && symbol.parent && !findAncestor(symbol.parent.valueDeclaration, d => node === d)) { + node = symbol.parent.valueDeclaration!; + } + } + } + if (!node) { + return undefined; + } + switch (node.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.CallSignature: + case SyntaxKind.ConstructSignature: + case SyntaxKind.MethodSignature: + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.JSDocFunctionType: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.JSDocTemplateTag: + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocEnumTag: + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.MappedType: + case SyntaxKind.ConditionalType: { + const outerTypeParameters = getOuterTypeParameters(node, includeThisTypes); + if (node.kind === SyntaxKind.MappedType) { + return append(outerTypeParameters, getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration((node as MappedTypeNode).typeParameter))); + } + else if (node.kind === SyntaxKind.ConditionalType) { + return concatenate(outerTypeParameters, getInferTypeParameters(node as ConditionalTypeNode)); + } + const outerAndOwnTypeParameters = appendTypeParameters(outerTypeParameters, getEffectiveTypeParameterDeclarations(node as DeclarationWithTypeParameters)); + const thisType = includeThisTypes && + (node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression || node.kind === SyntaxKind.InterfaceDeclaration || isJSConstructor(node)) && + getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node as ClassLikeDeclaration | InterfaceDeclaration)).thisType; + return thisType ? append(outerAndOwnTypeParameters, thisType) : outerAndOwnTypeParameters; + } + case SyntaxKind.JSDocParameterTag: + const paramSymbol = getParameterSymbolFromJSDoc(node as JSDocParameterTag); + if (paramSymbol) { + node = paramSymbol.valueDeclaration!; + } + break; + case SyntaxKind.JSDoc: { + const outerTypeParameters = getOuterTypeParameters(node, includeThisTypes); + return (node as JSDoc).tags + ? appendTypeParameters(outerTypeParameters, flatMap((node as JSDoc).tags, t => isJSDocTemplateTag(t) ? t.typeParameters : undefined)) + : outerTypeParameters; + } + } + } + } + + // The outer type parameters are those defined by enclosing generic classes, methods, or functions. + function getOuterTypeParametersOfClassOrInterface(symbol: Symbol): TypeParameter[] | undefined { + const declaration = (symbol.flags & SymbolFlags.Class || symbol.flags & SymbolFlags.Function) + ? symbol.valueDeclaration + : symbol.declarations?.find(decl => { + if (decl.kind === SyntaxKind.InterfaceDeclaration) { + return true; + } + if (decl.kind !== SyntaxKind.VariableDeclaration) { + return false; + } + const initializer = (decl as VariableDeclaration).initializer; + return !!initializer && (initializer.kind === SyntaxKind.FunctionExpression || initializer.kind === SyntaxKind.ArrowFunction); + })!; + Debug.assert(!!declaration, "Class was missing valueDeclaration -OR- non-class had no interface declarations"); + return getOuterTypeParameters(declaration); + } + + // The local type parameters are the combined set of type parameters from all declarations of the class, + // interface, or type alias. + function getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol: Symbol): TypeParameter[] | undefined { + if (!symbol.declarations) { + return; + } + let result: TypeParameter[] | undefined; + for (const node of symbol.declarations) { + if ( + node.kind === SyntaxKind.InterfaceDeclaration || + node.kind === SyntaxKind.ClassDeclaration || + node.kind === SyntaxKind.ClassExpression || + isJSConstructor(node) || + isTypeAlias(node) + ) { + const declaration = node as InterfaceDeclaration | TypeAliasDeclaration | JSDocTypedefTag | JSDocCallbackTag; + result = appendTypeParameters(result, getEffectiveTypeParameterDeclarations(declaration)); + } + } + return result; + } + + // The full set of type parameters for a generic class or interface type consists of its outer type parameters plus + // its locally declared type parameters. + function getTypeParametersOfClassOrInterface(symbol: Symbol): TypeParameter[] | undefined { + return concatenate(getOuterTypeParametersOfClassOrInterface(symbol), getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol)); + } + + // A type is a mixin constructor if it has a single construct signature taking no type parameters and a single + // rest parameter of type any[]. + function isMixinConstructorType(type: Type) { + const signatures = getSignaturesOfType(type, SignatureKind.Construct); + if (signatures.length === 1) { + const s = signatures[0]; + if (!s.typeParameters && s.parameters.length === 1 && signatureHasRestParameter(s)) { + const paramType = getTypeOfParameter(s.parameters[0]); + return isTypeAny(paramType) || getElementTypeOfArrayType(paramType) === anyType; + } + } + return false; + } + + function isConstructorType(type: Type): boolean { + if (getSignaturesOfType(type, SignatureKind.Construct).length > 0) { + return true; + } + if (type.flags & TypeFlags.TypeVariable) { + const constraint = getBaseConstraintOfType(type); + return !!constraint && isMixinConstructorType(constraint); + } + return false; + } + + function getBaseTypeNodeOfClass(type: InterfaceType): ExpressionWithTypeArguments | undefined { + const decl = getClassLikeDeclarationOfSymbol(type.symbol); + return decl && getEffectiveBaseTypeNode(decl); + } + + function getConstructorsForTypeArguments(type: Type, typeArgumentNodes: readonly TypeNode[] | undefined, location: Node): readonly Signature[] { + const typeArgCount = length(typeArgumentNodes); + const isJavascript = isInJSFile(location); + return filter(getSignaturesOfType(type, SignatureKind.Construct), sig => (isJavascript || typeArgCount >= getMinTypeArgumentCount(sig.typeParameters)) && typeArgCount <= length(sig.typeParameters)); + } + + function getInstantiatedConstructorsForTypeArguments(type: Type, typeArgumentNodes: readonly TypeNode[] | undefined, location: Node): readonly Signature[] { + const signatures = getConstructorsForTypeArguments(type, typeArgumentNodes, location); + const typeArguments = map(typeArgumentNodes, getTypeFromTypeNode); + return sameMap(signatures, sig => some(sig.typeParameters) ? getSignatureInstantiation(sig, typeArguments, isInJSFile(location)) : sig); + } + + /** + * The base constructor of a class can resolve to + * * undefinedType if the class has no extends clause, + * * errorType if an error occurred during resolution of the extends expression, + * * nullType if the extends expression is the null value, + * * anyType if the extends expression has type any, or + * * an object type with at least one construct signature. + */ + function getBaseConstructorTypeOfClass(type: InterfaceType): Type { + if (!type.resolvedBaseConstructorType) { + const decl = getClassLikeDeclarationOfSymbol(type.symbol); + const extended = decl && getEffectiveBaseTypeNode(decl); + const baseTypeNode = getBaseTypeNodeOfClass(type); + if (!baseTypeNode) { + return type.resolvedBaseConstructorType = undefinedType; + } + if (!pushTypeResolution(type, TypeSystemPropertyName.ResolvedBaseConstructorType)) { + return errorType; + } + const baseConstructorType = checkExpression(baseTypeNode.expression); + if (extended && baseTypeNode !== extended) { + Debug.assert(!extended.typeArguments); // Because this is in a JS file, and baseTypeNode is in an @extends tag + checkExpression(extended.expression); + } + if (baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection)) { + // Resolving the members of a class requires us to resolve the base class of that class. + // We force resolution here such that we catch circularities now. + resolveStructuredTypeMembers(baseConstructorType as ObjectType); + } + if (!popTypeResolution()) { + error(type.symbol.valueDeclaration, Diagnostics._0_is_referenced_directly_or_indirectly_in_its_own_base_expression, symbolToString(type.symbol)); + return type.resolvedBaseConstructorType ??= errorType; + } + if (!(baseConstructorType.flags & TypeFlags.Any) && baseConstructorType !== nullWideningType && !isConstructorType(baseConstructorType)) { + const err = error(baseTypeNode.expression, Diagnostics.Type_0_is_not_a_constructor_function_type, typeToString(baseConstructorType)); + if (baseConstructorType.flags & TypeFlags.TypeParameter) { + const constraint = getConstraintFromTypeParameter(baseConstructorType); + let ctorReturn: Type = unknownType; + if (constraint) { + const ctorSig = getSignaturesOfType(constraint, SignatureKind.Construct); + if (ctorSig[0]) { + ctorReturn = getReturnTypeOfSignature(ctorSig[0]); + } + } + if (baseConstructorType.symbol.declarations) { + addRelatedInfo(err, createDiagnosticForNode(baseConstructorType.symbol.declarations[0], Diagnostics.Did_you_mean_for_0_to_be_constrained_to_type_new_args_Colon_any_1, symbolToString(baseConstructorType.symbol), typeToString(ctorReturn))); + } + } + return type.resolvedBaseConstructorType ??= errorType; + } + type.resolvedBaseConstructorType ??= baseConstructorType; + } + return type.resolvedBaseConstructorType; + } + + function getImplementsTypes(type: InterfaceType): BaseType[] { + let resolvedImplementsTypes: BaseType[] = emptyArray; + if (type.symbol.declarations) { + for (const declaration of type.symbol.declarations) { + const implementsTypeNodes = getEffectiveImplementsTypeNodes(declaration as ClassLikeDeclaration); + if (!implementsTypeNodes) continue; + for (const node of implementsTypeNodes) { + const implementsType = getTypeFromTypeNode(node); + if (!isErrorType(implementsType)) { + if (resolvedImplementsTypes === emptyArray) { + resolvedImplementsTypes = [implementsType as ObjectType]; + } + else { + resolvedImplementsTypes.push(implementsType); + } + } + } + } + } + return resolvedImplementsTypes; + } + + function reportCircularBaseType(node: Node, type: Type) { + error(node, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType)); + } + + function getBaseTypes(type: InterfaceType): BaseType[] { + if (!type.baseTypesResolved) { + if (pushTypeResolution(type, TypeSystemPropertyName.ResolvedBaseTypes)) { + if (type.objectFlags & ObjectFlags.Tuple) { + type.resolvedBaseTypes = [getTupleBaseType(type as TupleType)]; + } + else if (type.symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { + if (type.symbol.flags & SymbolFlags.Class) { + resolveBaseTypesOfClass(type); + } + if (type.symbol.flags & SymbolFlags.Interface) { + resolveBaseTypesOfInterface(type); + } + } + else { + Debug.fail("type must be class or interface"); + } + if (!popTypeResolution() && type.symbol.declarations) { + for (const declaration of type.symbol.declarations) { + if (declaration.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.InterfaceDeclaration) { + reportCircularBaseType(declaration, type); + } + } + } + } + type.baseTypesResolved = true; + } + return type.resolvedBaseTypes; + } + + function getTupleBaseType(type: TupleType) { + const elementTypes = sameMap(type.typeParameters, (t, i) => type.elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t); + return createArrayType(getUnionType(elementTypes || emptyArray), type.readonly); + } + + function resolveBaseTypesOfClass(type: InterfaceType) { + type.resolvedBaseTypes = resolvingEmptyArray; + const baseConstructorType = getApparentType(getBaseConstructorTypeOfClass(type)); + if (!(baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Any))) { + return type.resolvedBaseTypes = emptyArray; + } + const baseTypeNode = getBaseTypeNodeOfClass(type)!; + let baseType: Type; + const originalBaseType = baseConstructorType.symbol ? getDeclaredTypeOfSymbol(baseConstructorType.symbol) : undefined; + if ( + baseConstructorType.symbol && baseConstructorType.symbol.flags & SymbolFlags.Class && + areAllOuterTypeParametersApplied(originalBaseType!) + ) { + // When base constructor type is a class with no captured type arguments we know that the constructors all have the same type parameters as the + // class and all return the instance type of the class. There is no need for further checks and we can apply the + // type arguments in the same manner as a type reference to get the same error reporting experience. + baseType = getTypeFromClassOrInterfaceReference(baseTypeNode, baseConstructorType.symbol); + } + else if (baseConstructorType.flags & TypeFlags.Any) { + baseType = baseConstructorType; + } + else { + // The class derives from a "class-like" constructor function, check that we have at least one construct signature + // with a matching number of type parameters and use the return type of the first instantiated signature. Elsewhere + // we check that all instantiated signatures return the same type. + const constructors = getInstantiatedConstructorsForTypeArguments(baseConstructorType, baseTypeNode.typeArguments, baseTypeNode); + if (!constructors.length) { + error(baseTypeNode.expression, Diagnostics.No_base_constructor_has_the_specified_number_of_type_arguments); + return type.resolvedBaseTypes = emptyArray; + } + baseType = getReturnTypeOfSignature(constructors[0]); + } + + if (isErrorType(baseType)) { + return type.resolvedBaseTypes = emptyArray; + } + const reducedBaseType = getReducedType(baseType); + if (!isValidBaseType(reducedBaseType)) { + const elaboration = elaborateNeverIntersection(/*errorInfo*/ undefined, baseType); + const diagnostic = chainDiagnosticMessages(elaboration, Diagnostics.Base_constructor_return_type_0_is_not_an_object_type_or_intersection_of_object_types_with_statically_known_members, typeToString(reducedBaseType)); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(baseTypeNode.expression), baseTypeNode.expression, diagnostic)); + return type.resolvedBaseTypes = emptyArray; + } + if (type === reducedBaseType || hasBaseType(reducedBaseType, type)) { + error(type.symbol.valueDeclaration, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType)); + return type.resolvedBaseTypes = emptyArray; + } + if (type.resolvedBaseTypes === resolvingEmptyArray) { + // Circular reference, likely through instantiation of default parameters + // (otherwise there'd be an error from hasBaseType) - this is fine, but `.members` should be reset + // as `getIndexedAccessType` via `instantiateType` via `getTypeFromClassOrInterfaceReference` forces a + // partial instantiation of the members without the base types fully resolved + type.members = undefined; + } + return type.resolvedBaseTypes = [reducedBaseType]; + } + + function areAllOuterTypeParametersApplied(type: Type): boolean { // TODO: GH#18217 Shouldn't this take an InterfaceType? + // An unapplied type parameter has its symbol still the same as the matching argument symbol. + // Since parameters are applied outer-to-inner, only the last outer parameter needs to be checked. + const outerTypeParameters = (type as InterfaceType).outerTypeParameters; + if (outerTypeParameters) { + const last = outerTypeParameters.length - 1; + const typeArguments = getTypeArguments(type as TypeReference); + return outerTypeParameters[last].symbol !== typeArguments[last].symbol; + } + return true; + } + + // A valid base type is `any`, an object type or intersection of object types. + function isValidBaseType(type: Type): type is BaseType { + if (type.flags & TypeFlags.TypeParameter) { + const constraint = getBaseConstraintOfType(type); + if (constraint) { + return isValidBaseType(constraint); + } + } + // TODO: Given that we allow type parmeters here now, is this `!isGenericMappedType(type)` check really needed? + // There's no reason a `T` should be allowed while a `Readonly` should not. + return !!(type.flags & (TypeFlags.Object | TypeFlags.NonPrimitive | TypeFlags.Any) && !isGenericMappedType(type) || + type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, isValidBaseType)); + } + + function resolveBaseTypesOfInterface(type: InterfaceType): void { + type.resolvedBaseTypes = type.resolvedBaseTypes || emptyArray; + if (type.symbol.declarations) { + for (const declaration of type.symbol.declarations) { + if (declaration.kind === SyntaxKind.InterfaceDeclaration && getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration)) { + for (const node of getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration)!) { + const baseType = getReducedType(getTypeFromTypeNode(node)); + if (!isErrorType(baseType)) { + if (isValidBaseType(baseType)) { + if (type !== baseType && !hasBaseType(baseType, type)) { + if (type.resolvedBaseTypes === emptyArray) { + type.resolvedBaseTypes = [baseType as ObjectType]; + } + else { + type.resolvedBaseTypes.push(baseType); + } + } + else { + reportCircularBaseType(declaration, type); + } + } + else { + error(node, Diagnostics.An_interface_can_only_extend_an_object_type_or_intersection_of_object_types_with_statically_known_members); + } + } + } + } + } + } + } + + /** + * Returns true if the interface given by the symbol is free of "this" references. + * + * Specifically, the result is true if the interface itself contains no references + * to "this" in its body, if all base types are interfaces, + * and if none of the base interfaces have a "this" type. + */ + function isThislessInterface(symbol: Symbol): boolean { + if (!symbol.declarations) { + return true; + } + for (const declaration of symbol.declarations) { + if (declaration.kind === SyntaxKind.InterfaceDeclaration) { + if (declaration.flags & NodeFlags.ContainsThis) { + return false; + } + const baseTypeNodes = getInterfaceBaseTypeNodes(declaration as InterfaceDeclaration); + if (baseTypeNodes) { + for (const node of baseTypeNodes) { + if (isEntityNameExpression(node.expression)) { + const baseSymbol = resolveEntityName(node.expression, SymbolFlags.Type, /*ignoreErrors*/ true); + if (!baseSymbol || !(baseSymbol.flags & SymbolFlags.Interface) || getDeclaredTypeOfClassOrInterface(baseSymbol).thisType) { + return false; + } + } + } + } + } + } + return true; + } + + function getDeclaredTypeOfClassOrInterface(symbol: Symbol): InterfaceType { + let links = getSymbolLinks(symbol); + const originalLinks = links; + if (!links.declaredType) { + const kind = symbol.flags & SymbolFlags.Class ? ObjectFlags.Class : ObjectFlags.Interface; + const merged = mergeJSSymbols(symbol, symbol.valueDeclaration && getAssignedClassSymbol(symbol.valueDeclaration)); + if (merged) { + // note:we overwrite links because we just cloned the symbol + symbol = merged; + links = merged.links; + } + + const type = originalLinks.declaredType = links.declaredType = createObjectType(kind, symbol) as InterfaceType; + const outerTypeParameters = getOuterTypeParametersOfClassOrInterface(symbol); + const localTypeParameters = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + // A class or interface is generic if it has type parameters or a "this" type. We always give classes a "this" type + // because it is not feasible to analyze all members to determine if the "this" type escapes the class (in particular, + // property types inferred from initializers and method return types inferred from return statements are very hard + // to exhaustively analyze). We give interfaces a "this" type if we can't definitely determine that they are free of + // "this" references. + if (outerTypeParameters || localTypeParameters || kind === ObjectFlags.Class || !isThislessInterface(symbol)) { + type.objectFlags |= ObjectFlags.Reference; + type.typeParameters = concatenate(outerTypeParameters, localTypeParameters); + type.outerTypeParameters = outerTypeParameters; + type.localTypeParameters = localTypeParameters; + (type as GenericType).instantiations = new Map(); + (type as GenericType).instantiations.set(getTypeListId(type.typeParameters), type as GenericType); + (type as GenericType).target = type as GenericType; + (type as GenericType).resolvedTypeArguments = type.typeParameters; + type.thisType = createTypeParameter(symbol); + type.thisType.isThisType = true; + type.thisType.constraint = type; + } + } + return links.declaredType as InterfaceType; + } + + function getDeclaredTypeOfTypeAlias(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.declaredType) { + // Note that we use the links object as the target here because the symbol object is used as the unique + // identity for resolution of the 'type' property in SymbolLinks. + if (!pushTypeResolution(symbol, TypeSystemPropertyName.DeclaredType)) { + return errorType; + } + + const declaration = Debug.checkDefined(symbol.declarations?.find(isTypeAlias), "Type alias symbol with no valid declaration found"); + const typeNode = isJSDocTypeAlias(declaration) ? declaration.typeExpression : declaration.type; + // If typeNode is missing, we will error in checkJSDocTypedefTag. + let type = typeNode ? getTypeFromTypeNode(typeNode) : errorType; + + if (popTypeResolution()) { + const typeParameters = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol); + if (typeParameters) { + // Initialize the instantiation cache for generic type aliases. The declared type corresponds to + // an instantiation of the type alias with the type parameters supplied as type arguments. + links.typeParameters = typeParameters; + links.instantiations = new Map(); + links.instantiations.set(getTypeListId(typeParameters), type); + } + } + else { + type = errorType; + if (declaration.kind === SyntaxKind.JSDocEnumTag) { + error(declaration.typeExpression.type, Diagnostics.Type_alias_0_circularly_references_itself, symbolToString(symbol)); + } + else { + error(isNamedDeclaration(declaration) ? declaration.name || declaration : declaration, Diagnostics.Type_alias_0_circularly_references_itself, symbolToString(symbol)); + } + } + links.declaredType ??= type; + } + return links.declaredType; + } + + function getBaseTypeOfEnumLikeType(type: Type) { + return type.flags & TypeFlags.EnumLike && type.symbol.flags & SymbolFlags.EnumMember ? getDeclaredTypeOfSymbol(getParentOfSymbol(type.symbol)!) : type; + } + + function getDeclaredTypeOfEnum(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.declaredType) { + const memberTypeList: Type[] = []; + if (symbol.declarations) { + for (const declaration of symbol.declarations) { + if (declaration.kind === SyntaxKind.EnumDeclaration) { + for (const member of (declaration as EnumDeclaration).members) { + if (hasBindableName(member)) { + const memberSymbol = getSymbolOfDeclaration(member); + const value = getEnumMemberValue(member).value; + const memberType = getFreshTypeOfLiteralType( + value !== undefined ? + getEnumLiteralType(value, getSymbolId(symbol), memberSymbol) : + createComputedEnumType(memberSymbol), + ); + getSymbolLinks(memberSymbol).declaredType = memberType; + memberTypeList.push(getRegularTypeOfLiteralType(memberType)); + } + } + } + } + } + const enumType = memberTypeList.length ? + getUnionType(memberTypeList, UnionReduction.Literal, symbol, /*aliasTypeArguments*/ undefined) : + createComputedEnumType(symbol); + if (enumType.flags & TypeFlags.Union) { + enumType.flags |= TypeFlags.EnumLiteral; + enumType.symbol = symbol; + } + links.declaredType = enumType; + } + return links.declaredType; + } + + function createComputedEnumType(symbol: Symbol) { + const regularType = createTypeWithSymbol(TypeFlags.Enum, symbol) as EnumType; + const freshType = createTypeWithSymbol(TypeFlags.Enum, symbol) as EnumType; + regularType.regularType = regularType; + regularType.freshType = freshType; + freshType.regularType = regularType; + freshType.freshType = freshType; + return regularType; + } + + function getDeclaredTypeOfEnumMember(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + if (!links.declaredType) { + const enumType = getDeclaredTypeOfEnum(getParentOfSymbol(symbol)!); + if (!links.declaredType) { + links.declaredType = enumType; + } + } + return links.declaredType; + } + + function getDeclaredTypeOfTypeParameter(symbol: Symbol): TypeParameter { + const links = getSymbolLinks(symbol); + return links.declaredType || (links.declaredType = createTypeParameter(symbol)); + } + + function getDeclaredTypeOfAlias(symbol: Symbol): Type { + const links = getSymbolLinks(symbol); + return links.declaredType || (links.declaredType = getDeclaredTypeOfSymbol(resolveAlias(symbol))); + } + + function getDeclaredTypeOfSymbol(symbol: Symbol): Type { + return tryGetDeclaredTypeOfSymbol(symbol) || errorType; + } + + function tryGetDeclaredTypeOfSymbol(symbol: Symbol): Type | undefined { + if (symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { + return getDeclaredTypeOfClassOrInterface(symbol); + } + if (symbol.flags & SymbolFlags.TypeAlias) { + return getDeclaredTypeOfTypeAlias(symbol); + } + if (symbol.flags & SymbolFlags.TypeParameter) { + return getDeclaredTypeOfTypeParameter(symbol); + } + if (symbol.flags & SymbolFlags.Enum) { + return getDeclaredTypeOfEnum(symbol); + } + if (symbol.flags & SymbolFlags.EnumMember) { + return getDeclaredTypeOfEnumMember(symbol); + } + if (symbol.flags & SymbolFlags.Alias) { + return getDeclaredTypeOfAlias(symbol); + } + return undefined; + } + + /** + * A type is free of this references if it's the any, string, number, boolean, symbol, or void keyword, a string + * literal type, an array with an element type that is free of this references, or a type reference that is + * free of this references. + */ + function isThislessType(node: TypeNode): boolean { + switch (node.kind) { + case SyntaxKind.AnyKeyword: + case SyntaxKind.UnknownKeyword: + case SyntaxKind.StringKeyword: + case SyntaxKind.NumberKeyword: + case SyntaxKind.BigIntKeyword: + case SyntaxKind.BooleanKeyword: + case SyntaxKind.SymbolKeyword: + case SyntaxKind.ObjectKeyword: + case SyntaxKind.VoidKeyword: + case SyntaxKind.UndefinedKeyword: + case SyntaxKind.NeverKeyword: + case SyntaxKind.LiteralType: + return true; + case SyntaxKind.ArrayType: + return isThislessType((node as ArrayTypeNode).elementType); + case SyntaxKind.TypeReference: + return !(node as TypeReferenceNode).typeArguments || (node as TypeReferenceNode).typeArguments!.every(isThislessType); + } + return false; + } + + /** A type parameter is thisless if its constraint is thisless, or if it has no constraint. */ + function isThislessTypeParameter(node: TypeParameterDeclaration) { + const constraint = getEffectiveConstraintOfTypeParameter(node); + return !constraint || isThislessType(constraint); + } + + /** + * A variable-like declaration is free of this references if it has a type annotation + * that is thisless, or if it has no type annotation and no initializer (and is thus of type any). + */ + function isThislessVariableLikeDeclaration(node: VariableLikeDeclaration): boolean { + const typeNode = getEffectiveTypeAnnotationNode(node); + return typeNode ? isThislessType(typeNode) : !hasInitializer(node); + } + + /** + * A function-like declaration is considered free of `this` references if it has a return type + * annotation that is free of this references and if each parameter is thisless and if + * each type parameter (if present) is thisless. + */ + function isThislessFunctionLikeDeclaration(node: FunctionLikeDeclaration): boolean { + const returnType = getEffectiveReturnTypeNode(node); + const typeParameters = getEffectiveTypeParameterDeclarations(node); + return (node.kind === SyntaxKind.Constructor || (!!returnType && isThislessType(returnType))) && + node.parameters.every(isThislessVariableLikeDeclaration) && + typeParameters.every(isThislessTypeParameter); + } + + /** + * Returns true if the class or interface member given by the symbol is free of "this" references. The + * function may return false for symbols that are actually free of "this" references because it is not + * feasible to perform a complete analysis in all cases. In particular, property members with types + * inferred from their initializers and function members with inferred return types are conservatively + * assumed not to be free of "this" references. + */ + function isThisless(symbol: Symbol): boolean { + if (symbol.declarations && symbol.declarations.length === 1) { + const declaration = symbol.declarations[0]; + if (declaration) { + switch (declaration.kind) { + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + return isThislessVariableLikeDeclaration(declaration as VariableLikeDeclaration); + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + case SyntaxKind.Constructor: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return isThislessFunctionLikeDeclaration(declaration as FunctionLikeDeclaration | AccessorDeclaration); + } + } + } + return false; + } + + // The mappingThisOnly flag indicates that the only type parameter being mapped is "this". When the flag is true, + // we check symbols to see if we can quickly conclude they are free of "this" references, thus needing no instantiation. + function createInstantiatedSymbolTable(symbols: Symbol[], mapper: TypeMapper, mappingThisOnly: boolean): SymbolTable { + const result = createSymbolTable(); + for (const symbol of symbols) { + result.set(symbol.escapedName, mappingThisOnly && isThisless(symbol) ? symbol : instantiateSymbol(symbol, mapper)); + } + return result; + } + + function addInheritedMembers(symbols: SymbolTable, baseSymbols: Symbol[]) { + for (const base of baseSymbols) { + if (isStaticPrivateIdentifierProperty(base)) { + continue; + } + const derived = symbols.get(base.escapedName); + if ( + !derived + // non-constructor/static-block assignment declarations are ignored here; they're not treated as overrides + || derived.valueDeclaration + && isBinaryExpression(derived.valueDeclaration) + && !isConstructorDeclaredProperty(derived) + && !getContainingClassStaticBlock(derived.valueDeclaration) + ) { + symbols.set(base.escapedName, base); + symbols.set(base.escapedName, base); + } + } + } + + function isStaticPrivateIdentifierProperty(s: Symbol): boolean { + return !!s.valueDeclaration && isPrivateIdentifierClassElementDeclaration(s.valueDeclaration) && isStatic(s.valueDeclaration); + } + + function resolveDeclaredMembers(type: InterfaceType): InterfaceTypeWithDeclaredMembers { + if (!(type as InterfaceTypeWithDeclaredMembers).declaredProperties) { + const symbol = type.symbol; + const members = getMembersOfSymbol(symbol); + (type as InterfaceTypeWithDeclaredMembers).declaredProperties = getNamedMembers(members); + // Start with signatures at empty array in case of recursive types + (type as InterfaceTypeWithDeclaredMembers).declaredCallSignatures = emptyArray; + (type as InterfaceTypeWithDeclaredMembers).declaredConstructSignatures = emptyArray; + (type as InterfaceTypeWithDeclaredMembers).declaredIndexInfos = emptyArray; + + (type as InterfaceTypeWithDeclaredMembers).declaredCallSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.Call)); + (type as InterfaceTypeWithDeclaredMembers).declaredConstructSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.New)); + (type as InterfaceTypeWithDeclaredMembers).declaredIndexInfos = getIndexInfosOfSymbol(symbol); + } + return type as InterfaceTypeWithDeclaredMembers; + } + + /** + * Indicates whether a declaration name is definitely late-bindable. + * A declaration name is only late-bindable if: + * - It is a `ComputedPropertyName`. + * - Its expression is an `Identifier` or either a `PropertyAccessExpression` an + * `ElementAccessExpression` consisting only of these same three types of nodes. + * - The type of its expression is a string or numeric literal type, or is a `unique symbol` type. + */ + function isLateBindableName(node: DeclarationName): node is LateBoundName { + if (!isComputedPropertyName(node) && !isElementAccessExpression(node)) { + return false; + } + const expr = isComputedPropertyName(node) ? node.expression : node.argumentExpression; + return isEntityNameExpression(expr) + && isTypeUsableAsPropertyName(isComputedPropertyName(node) ? checkComputedPropertyName(node) : checkExpressionCached(expr)); + } + + function isLateBoundName(name: __String): boolean { + return (name as string).charCodeAt(0) === CharacterCodes._ && + (name as string).charCodeAt(1) === CharacterCodes._ && + (name as string).charCodeAt(2) === CharacterCodes.at; + } + + /** + * Indicates whether a declaration has a late-bindable dynamic name. + */ + function hasLateBindableName(node: Declaration): node is LateBoundDeclaration | LateBoundBinaryExpressionDeclaration { + const name = getNameOfDeclaration(node); + return !!name && isLateBindableName(name); + } + + /** + * Indicates whether a declaration has an early-bound name or a dynamic name that can be late-bound. + */ + function hasBindableName(node: Declaration) { + return !hasDynamicName(node) || hasLateBindableName(node); + } + + /** + * Indicates whether a declaration name is a dynamic name that cannot be late-bound. + */ + function isNonBindableDynamicName(node: DeclarationName) { + return isDynamicName(node) && !isLateBindableName(node); + } + + /** + * Adds a declaration to a late-bound dynamic member. This performs the same function for + * late-bound members that `addDeclarationToSymbol` in binder.ts performs for early-bound + * members. + */ + function addDeclarationToLateBoundSymbol(symbol: Symbol, member: LateBoundDeclaration | BinaryExpression, symbolFlags: SymbolFlags) { + Debug.assert(!!(getCheckFlags(symbol) & CheckFlags.Late), "Expected a late-bound symbol."); + symbol.flags |= symbolFlags; + getSymbolLinks(member.symbol).lateSymbol = symbol; + if (!symbol.declarations) { + symbol.declarations = [member]; + } + else if (!member.symbol.isReplaceableByMethod) { + symbol.declarations.push(member); + } + if (symbolFlags & SymbolFlags.Value) { + if (!symbol.valueDeclaration || symbol.valueDeclaration.kind !== member.kind) { + symbol.valueDeclaration = member; + } + } + } + + /** + * Performs late-binding of a dynamic member. This performs the same function for + * late-bound members that `declareSymbol` in binder.ts performs for early-bound + * members. + * + * If a symbol is a dynamic name from a computed property, we perform an additional "late" + * binding phase to attempt to resolve the name for the symbol from the type of the computed + * property's expression. If the type of the expression is a string-literal, numeric-literal, + * or unique symbol type, we can use that type as the name of the symbol. + * + * For example, given: + * + * const x = Symbol(); + * + * interface I { + * [x]: number; + * } + * + * The binder gives the property `[x]: number` a special symbol with the name "__computed". + * In the late-binding phase we can type-check the expression `x` and see that it has a + * unique symbol type which we can then use as the name of the member. This allows users + * to define custom symbols that can be used in the members of an object type. + * + * @param parent The containing symbol for the member. + * @param earlySymbols The early-bound symbols of the parent. + * @param lateSymbols The late-bound symbols of the parent. + * @param decl The member to bind. + */ + function lateBindMember(parent: Symbol, earlySymbols: SymbolTable | undefined, lateSymbols: Map<__String, TransientSymbol>, decl: LateBoundDeclaration | LateBoundBinaryExpressionDeclaration) { + Debug.assert(!!decl.symbol, "The member is expected to have a symbol."); + const links = getNodeLinks(decl); + if (!links.resolvedSymbol) { + // In the event we attempt to resolve the late-bound name of this member recursively, + // fall back to the early-bound name of this member. + links.resolvedSymbol = decl.symbol; + const declName = isBinaryExpression(decl) ? decl.left : decl.name; + const type = isElementAccessExpression(declName) ? checkExpressionCached(declName.argumentExpression) : checkComputedPropertyName(declName); + if (isTypeUsableAsPropertyName(type)) { + const memberName = getPropertyNameFromType(type); + const symbolFlags = decl.symbol.flags; + + // Get or add a late-bound symbol for the member. This allows us to merge late-bound accessor declarations. + let lateSymbol = lateSymbols.get(memberName); + if (!lateSymbol) lateSymbols.set(memberName, lateSymbol = createSymbol(SymbolFlags.None, memberName, CheckFlags.Late)); + + // Report an error if there's a symbol declaration with the same name and conflicting flags. + const earlySymbol = earlySymbols && earlySymbols.get(memberName); + // Duplicate property declarations of classes are checked in checkClassForDuplicateDeclarations. + if (!(parent.flags & SymbolFlags.Class) && lateSymbol.flags & getExcludedSymbolFlags(symbolFlags)) { + // If we have an existing early-bound member, combine its declarations so that we can + // report an error at each declaration. + const declarations = earlySymbol ? concatenate(earlySymbol.declarations, lateSymbol.declarations) : lateSymbol.declarations; + const name = !(type.flags & TypeFlags.UniqueESSymbol) && unescapeLeadingUnderscores(memberName) || declarationNameToString(declName); + forEach(declarations, declaration => error(getNameOfDeclaration(declaration) || declaration, Diagnostics.Property_0_was_also_declared_here, name)); + error(declName || decl, Diagnostics.Duplicate_property_0, name); + lateSymbol = createSymbol(SymbolFlags.None, memberName, CheckFlags.Late); + } + lateSymbol.links.nameType = type; + addDeclarationToLateBoundSymbol(lateSymbol, decl, symbolFlags); + if (lateSymbol.parent) { + Debug.assert(lateSymbol.parent === parent, "Existing symbol parent should match new one"); + } + else { + lateSymbol.parent = parent; + } + return links.resolvedSymbol = lateSymbol; + } + } + return links.resolvedSymbol; + } + + function getResolvedMembersOrExportsOfSymbol(symbol: Symbol, resolutionKind: MembersOrExportsResolutionKind): Map<__String, Symbol> { + const links = getSymbolLinks(symbol); + if (!links[resolutionKind]) { + const isStatic = resolutionKind === MembersOrExportsResolutionKind.resolvedExports; + const earlySymbols = !isStatic ? symbol.members : + symbol.flags & SymbolFlags.Module ? getExportsOfModuleWorker(symbol).exports : + symbol.exports; + + // In the event we recursively resolve the members/exports of the symbol, we + // set the initial value of resolvedMembers/resolvedExports to the early-bound + // members/exports of the symbol. + links[resolutionKind] = earlySymbols || emptySymbols; + + // fill in any as-yet-unresolved late-bound members. + const lateSymbols = createSymbolTable() as Map<__String, TransientSymbol>; + for (const decl of symbol.declarations || emptyArray) { + const members = getMembersOfDeclaration(decl); + if (members) { + for (const member of members) { + if (isStatic === hasStaticModifier(member)) { + if (hasLateBindableName(member)) { + lateBindMember(symbol, earlySymbols, lateSymbols, member); + } + } + } + } + } + const assignments = getFunctionExpressionParentSymbolOrSymbol(symbol).assignmentDeclarationMembers; + + if (assignments) { + const decls = arrayFrom(assignments.values()); + for (const member of decls) { + const assignmentKind = getAssignmentDeclarationKind(member as BinaryExpression | CallExpression); + const isInstanceMember = assignmentKind === AssignmentDeclarationKind.PrototypeProperty + || isBinaryExpression(member) && isPossiblyAliasedThisProperty(member, assignmentKind) + || assignmentKind === AssignmentDeclarationKind.ObjectDefinePrototypeProperty + || assignmentKind === AssignmentDeclarationKind.Prototype; // A straight `Prototype` assignment probably can never have a computed name + if (isStatic === !isInstanceMember) { + if (hasLateBindableName(member)) { + lateBindMember(symbol, earlySymbols, lateSymbols, member); + } + } + } + } + + let resolved = combineSymbolTables(earlySymbols, lateSymbols); + if (symbol.flags & SymbolFlags.Transient && links.cjsExportMerged && symbol.declarations) { + for (const decl of symbol.declarations) { + const original = getSymbolLinks(decl.symbol)[resolutionKind]; + if (!resolved) { + resolved = original; + continue; + } + if (!original) continue; + original.forEach((s, name) => { + const existing = resolved!.get(name); + if (!existing) resolved!.set(name, s); + else if (existing === s) return; + else resolved!.set(name, mergeSymbol(existing, s)); + }); + } + } + links[resolutionKind] = resolved || emptySymbols; + } + + return links[resolutionKind]!; + } + + /** + * Gets a SymbolTable containing both the early- and late-bound members of a symbol. + * + * For a description of late-binding, see `lateBindMember`. + */ + function getMembersOfSymbol(symbol: Symbol) { + return symbol.flags & SymbolFlags.LateBindingContainer + ? getResolvedMembersOrExportsOfSymbol(symbol, MembersOrExportsResolutionKind.resolvedMembers) + : symbol.members || emptySymbols; + } + + /** + * If a symbol is the dynamic name of the member of an object type, get the late-bound + * symbol of the member. + * + * For a description of late-binding, see `lateBindMember`. + */ + function getLateBoundSymbol(symbol: Symbol): Symbol { + if (symbol.flags & SymbolFlags.ClassMember && symbol.escapedName === InternalSymbolName.Computed) { + const links = getSymbolLinks(symbol); + if (!links.lateSymbol && some(symbol.declarations, hasLateBindableName)) { + // force late binding of members/exports. This will set the late-bound symbol + const parent = getMergedSymbol(symbol.parent)!; + if (some(symbol.declarations, hasStaticModifier)) { + getExportsOfSymbol(parent); + } + else { + getMembersOfSymbol(parent); + } + } + return links.lateSymbol || (links.lateSymbol = symbol); + } + return symbol; + } + + function getTypeWithThisArgument(type: Type, thisArgument?: Type, needApparentType?: boolean): Type { + if (getObjectFlags(type) & ObjectFlags.Reference) { + const target = (type as TypeReference).target; + const typeArguments = getTypeArguments(type as TypeReference); + return length(target.typeParameters) === length(typeArguments) ? createTypeReference(target, concatenate(typeArguments, [thisArgument || target.thisType!])) : type; + } + else if (type.flags & TypeFlags.Intersection) { + const types = sameMap((type as IntersectionType).types, t => getTypeWithThisArgument(t, thisArgument, needApparentType)); + return types !== (type as IntersectionType).types ? getIntersectionType(types) : type; + } + return needApparentType ? getApparentType(type) : type; + } + + function resolveObjectTypeMembers(type: ObjectType, source: InterfaceTypeWithDeclaredMembers, typeParameters: readonly TypeParameter[], typeArguments: readonly Type[]) { + let mapper: TypeMapper | undefined; + let members: SymbolTable; + let callSignatures: readonly Signature[]; + let constructSignatures: readonly Signature[]; + let indexInfos: readonly IndexInfo[]; + if (rangeEquals(typeParameters, typeArguments, 0, typeParameters.length)) { + members = source.symbol ? getMembersOfSymbol(source.symbol) : createSymbolTable(source.declaredProperties); + callSignatures = source.declaredCallSignatures; + constructSignatures = source.declaredConstructSignatures; + indexInfos = source.declaredIndexInfos; + } + else { + mapper = createTypeMapper(typeParameters, typeArguments); + members = createInstantiatedSymbolTable(source.declaredProperties, mapper, /*mappingThisOnly*/ typeParameters.length === 1); + callSignatures = instantiateSignatures(source.declaredCallSignatures, mapper); + constructSignatures = instantiateSignatures(source.declaredConstructSignatures, mapper); + indexInfos = instantiateIndexInfos(source.declaredIndexInfos, mapper); + } + const baseTypes = getBaseTypes(source); + if (baseTypes.length) { + if (source.symbol && members === getMembersOfSymbol(source.symbol)) { + const symbolTable = createSymbolTable(source.declaredProperties); + // copy index signature symbol as well (for quickinfo) + const sourceIndex = getIndexSymbol(source.symbol); + if (sourceIndex) { + symbolTable.set(InternalSymbolName.Index, sourceIndex); + } + members = symbolTable; + } + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + const thisArgument = lastOrUndefined(typeArguments); + for (const baseType of baseTypes) { + const instantiatedBaseType = thisArgument ? getTypeWithThisArgument(instantiateType(baseType, mapper), thisArgument) : baseType; + addInheritedMembers(members, getPropertiesOfType(instantiatedBaseType)); + callSignatures = concatenate(callSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Call)); + constructSignatures = concatenate(constructSignatures, getSignaturesOfType(instantiatedBaseType, SignatureKind.Construct)); + const inheritedIndexInfos = instantiatedBaseType !== anyType ? getIndexInfosOfType(instantiatedBaseType) : [createIndexInfo(stringType, anyType, /*isReadonly*/ false)]; + indexInfos = concatenate(indexInfos, filter(inheritedIndexInfos, info => !findIndexInfo(indexInfos, info.keyType))); + } + } + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + } + + function resolveClassOrInterfaceMembers(type: InterfaceType): void { + resolveObjectTypeMembers(type, resolveDeclaredMembers(type), emptyArray, emptyArray); + } + + function resolveTypeReferenceMembers(type: TypeReference): void { + const source = resolveDeclaredMembers(type.target); + const typeParameters = concatenate(source.typeParameters!, [source.thisType!]); + const typeArguments = getTypeArguments(type); + const paddedTypeArguments = typeArguments.length === typeParameters.length ? typeArguments : concatenate(typeArguments, [type]); + resolveObjectTypeMembers(type, source, typeParameters, paddedTypeArguments); + } + + function createSignature( + declaration: SignatureDeclaration | JSDocSignature | undefined, + typeParameters: readonly TypeParameter[] | undefined, + thisParameter: Symbol | undefined, + parameters: readonly Symbol[], + resolvedReturnType: Type | undefined, + resolvedTypePredicate: TypePredicate | undefined, + minArgumentCount: number, + flags: SignatureFlags, + ): Signature { + const sig = new Signature(checker, flags); + sig.declaration = declaration; + sig.typeParameters = typeParameters; + sig.parameters = parameters; + sig.thisParameter = thisParameter; + sig.resolvedReturnType = resolvedReturnType; + sig.resolvedTypePredicate = resolvedTypePredicate; + sig.minArgumentCount = minArgumentCount; + sig.resolvedMinArgumentCount = undefined; + sig.target = undefined; + sig.mapper = undefined; + sig.compositeSignatures = undefined; + sig.compositeKind = undefined; + return sig; + } + + function cloneSignature(sig: Signature): Signature { + const result = createSignature(sig.declaration, sig.typeParameters, sig.thisParameter, sig.parameters, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, sig.minArgumentCount, sig.flags & SignatureFlags.PropagatingFlags); + result.target = sig.target; + result.mapper = sig.mapper; + result.compositeSignatures = sig.compositeSignatures; + result.compositeKind = sig.compositeKind; + return result; + } + + function createUnionSignature(signature: Signature, unionSignatures: Signature[]) { + const result = cloneSignature(signature); + result.compositeSignatures = unionSignatures; + result.compositeKind = TypeFlags.Union; + result.target = undefined; + result.mapper = undefined; + return result; + } + + function getOptionalCallSignature(signature: Signature, callChainFlags: SignatureFlags): Signature { + if ((signature.flags & SignatureFlags.CallChainFlags) === callChainFlags) { + return signature; + } + if (!signature.optionalCallSignatureCache) { + signature.optionalCallSignatureCache = {}; + } + const key = callChainFlags === SignatureFlags.IsInnerCallChain ? "inner" : "outer"; + return signature.optionalCallSignatureCache[key] + || (signature.optionalCallSignatureCache[key] = createOptionalCallSignature(signature, callChainFlags)); + } + + function createOptionalCallSignature(signature: Signature, callChainFlags: SignatureFlags) { + Debug.assert(callChainFlags === SignatureFlags.IsInnerCallChain || callChainFlags === SignatureFlags.IsOuterCallChain, "An optional call signature can either be for an inner call chain or an outer call chain, but not both."); + const result = cloneSignature(signature); + result.flags |= callChainFlags; + return result; + } + + function getExpandedParameters(sig: Signature, skipUnionExpanding?: boolean): readonly (readonly Symbol[])[] { + if (signatureHasRestParameter(sig)) { + const restIndex = sig.parameters.length - 1; + const restName = sig.parameters[restIndex].escapedName; + const restType = getTypeOfSymbol(sig.parameters[restIndex]); + if (isTupleType(restType)) { + return [expandSignatureParametersWithTupleMembers(restType, restIndex, restName)]; + } + else if (!skipUnionExpanding && restType.flags & TypeFlags.Union && every((restType as UnionType).types, isTupleType)) { + return map((restType as UnionType).types, t => expandSignatureParametersWithTupleMembers(t as TupleTypeReference, restIndex, restName)); + } + } + return [sig.parameters]; + + function expandSignatureParametersWithTupleMembers(restType: TupleTypeReference, restIndex: number, restName: __String) { + const elementTypes = getTypeArguments(restType); + const associatedNames = getUniqAssociatedNamesFromTupleType(restType, restName); + const restParams = map(elementTypes, (t, i) => { + // Lookup the label from the individual tuple passed in before falling back to the signature `rest` parameter name + const name = associatedNames && associatedNames[i] ? associatedNames[i] : + getParameterNameAtPosition(sig, restIndex + i, restType); + const flags = restType.target.elementFlags[i]; + const checkFlags = flags & ElementFlags.Variable ? CheckFlags.RestParameter : + flags & ElementFlags.Optional ? CheckFlags.OptionalParameter : 0; + const symbol = createSymbol(SymbolFlags.FunctionScopedVariable, name, checkFlags); + symbol.links.type = flags & ElementFlags.Rest ? createArrayType(t) : t; + return symbol; + }); + return concatenate(sig.parameters.slice(0, restIndex), restParams); + } + + function getUniqAssociatedNamesFromTupleType(type: TupleTypeReference, restName: __String) { + const associatedNamesMap = new Map<__String, number>(); + return map(type.target.labeledElementDeclarations, (labeledElement, i) => { + const name = getTupleElementLabel(labeledElement, i, restName); + const prevCounter = associatedNamesMap.get(name); + if (prevCounter === undefined) { + associatedNamesMap.set(name, 1); + return name; + } + else { + associatedNamesMap.set(name, prevCounter + 1); + return `${name}_${prevCounter}` as __String; + } + }); + } + } + + function getDefaultConstructSignatures(classType: InterfaceType): Signature[] { + const baseConstructorType = getBaseConstructorTypeOfClass(classType); + const baseSignatures = getSignaturesOfType(baseConstructorType, SignatureKind.Construct); + const declaration = getClassLikeDeclarationOfSymbol(classType.symbol); + const isAbstract = !!declaration && hasSyntacticModifier(declaration, ModifierFlags.Abstract); + if (baseSignatures.length === 0) { + return [createSignature(/*declaration*/ undefined, classType.localTypeParameters, /*thisParameter*/ undefined, emptyArray, classType, /*resolvedTypePredicate*/ undefined, 0, isAbstract ? SignatureFlags.Abstract : SignatureFlags.None)]; + } + const baseTypeNode = getBaseTypeNodeOfClass(classType)!; + const isJavaScript = isInJSFile(baseTypeNode); + const typeArguments = typeArgumentsFromTypeReferenceNode(baseTypeNode); + const typeArgCount = length(typeArguments); + const result: Signature[] = []; + for (const baseSig of baseSignatures) { + const minTypeArgumentCount = getMinTypeArgumentCount(baseSig.typeParameters); + const typeParamCount = length(baseSig.typeParameters); + if (isJavaScript || typeArgCount >= minTypeArgumentCount && typeArgCount <= typeParamCount) { + const sig = typeParamCount ? createSignatureInstantiation(baseSig, fillMissingTypeArguments(typeArguments, baseSig.typeParameters, minTypeArgumentCount, isJavaScript)) : cloneSignature(baseSig); + sig.typeParameters = classType.localTypeParameters; + sig.resolvedReturnType = classType; + sig.flags = isAbstract ? sig.flags | SignatureFlags.Abstract : sig.flags & ~SignatureFlags.Abstract; + result.push(sig); + } + } + return result; + } + + function findMatchingSignature(signatureList: readonly Signature[], signature: Signature, partialMatch: boolean, ignoreThisTypes: boolean, ignoreReturnTypes: boolean): Signature | undefined { + for (const s of signatureList) { + if (compareSignaturesIdentical(s, signature, partialMatch, ignoreThisTypes, ignoreReturnTypes, partialMatch ? compareTypesSubtypeOf : compareTypesIdentical)) { + return s; + } + } + } + + function findMatchingSignatures(signatureLists: readonly (readonly Signature[])[], signature: Signature, listIndex: number): Signature[] | undefined { + if (signature.typeParameters) { + // We require an exact match for generic signatures, so we only return signatures from the first + // signature list and only if they have exact matches in the other signature lists. + if (listIndex > 0) { + return undefined; + } + for (let i = 1; i < signatureLists.length; i++) { + if (!findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false)) { + return undefined; + } + } + return [signature]; + } + let result: Signature[] | undefined; + for (let i = 0; i < signatureLists.length; i++) { + // Allow matching non-generic signatures to have excess parameters (as a fallback if exact parameter match is not found) and different return types. + // Prefer matching this types if possible. + const match = i === listIndex + ? signature + : findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true) + || findMatchingSignature(signatureLists[i], signature, /*partialMatch*/ true, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true); + if (!match) { + return undefined; + } + result = appendIfUnique(result, match); + } + return result; + } + + // The signatures of a union type are those signatures that are present in each of the constituent types. + // Generic signatures must match exactly, but non-generic signatures are allowed to have extra optional + // parameters and may differ in return types. When signatures differ in return types, the resulting return + // type is the union of the constituent return types. + function getUnionSignatures(signatureLists: readonly (readonly Signature[])[]): Signature[] { + let result: Signature[] | undefined; + let indexWithLengthOverOne: number | undefined; + for (let i = 0; i < signatureLists.length; i++) { + if (signatureLists[i].length === 0) return emptyArray; + if (signatureLists[i].length > 1) { + indexWithLengthOverOne = indexWithLengthOverOne === undefined ? i : -1; // -1 is a signal there are multiple overload sets + } + for (const signature of signatureLists[i]) { + // Only process signatures with parameter lists that aren't already in the result list + if (!result || !findMatchingSignature(result, signature, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ true)) { + const unionSignatures = findMatchingSignatures(signatureLists, signature, i); + if (unionSignatures) { + let s = signature; + // Union the result types when more than one signature matches + if (unionSignatures.length > 1) { + let thisParameter = signature.thisParameter; + const firstThisParameterOfUnionSignatures = forEach(unionSignatures, sig => sig.thisParameter); + if (firstThisParameterOfUnionSignatures) { + const thisType = getIntersectionType(mapDefined(unionSignatures, sig => sig.thisParameter && getTypeOfSymbol(sig.thisParameter))); + thisParameter = createSymbolWithType(firstThisParameterOfUnionSignatures, thisType); + } + s = createUnionSignature(signature, unionSignatures); + s.thisParameter = thisParameter; + } + (result || (result = [])).push(s); + } + } + } + } + if (!length(result) && indexWithLengthOverOne !== -1) { + // No sufficiently similar signature existed to subsume all the other signatures in the union - time to see if we can make a single + // signature that handles all over them. We only do this when there are overloads in only one constituent. + // (Overloads are conditional in nature and having overloads in multiple constituents would necessitate making a power set of + // signatures from the type, whose ordering would be non-obvious) + const masterList = signatureLists[indexWithLengthOverOne !== undefined ? indexWithLengthOverOne : 0]; + let results: Signature[] | undefined = masterList.slice(); + for (const signatures of signatureLists) { + if (signatures !== masterList) { + const signature = signatures[0]; + Debug.assert(!!signature, "getUnionSignatures bails early on empty signature lists and should not have empty lists on second pass"); + results = !!signature.typeParameters && some(results, s => !!s.typeParameters && !compareTypeParametersIdentical(signature.typeParameters, s.typeParameters)) ? undefined : map(results, sig => combineSignaturesOfUnionMembers(sig, signature)); + if (!results) { + break; + } + } + } + result = results; + } + return result || emptyArray; + } + + function compareTypeParametersIdentical(sourceParams: readonly TypeParameter[] | undefined, targetParams: readonly TypeParameter[] | undefined): boolean { + if (length(sourceParams) !== length(targetParams)) { + return false; + } + if (!sourceParams || !targetParams) { + return true; + } + + const mapper = createTypeMapper(targetParams, sourceParams); + for (let i = 0; i < sourceParams.length; i++) { + const source = sourceParams[i]; + const target = targetParams[i]; + if (source === target) continue; + // We instantiate the target type parameter constraints into the source types so we can recognize `` as the same as `` + if (!isTypeIdenticalTo(getConstraintFromTypeParameter(source) || unknownType, instantiateType(getConstraintFromTypeParameter(target) || unknownType, mapper))) return false; + // We don't compare defaults - we just use the type parameter defaults from the first signature that seems to match. + // It might make sense to combine these defaults in the future, but doing so intelligently requires knowing + // if the parameter is used covariantly or contravariantly (so we intersect if it's used like a parameter or union if used like a return type) + // and, since it's just an inference _default_, just picking one arbitrarily works OK. + } + + return true; + } + + function combineUnionThisParam(left: Symbol | undefined, right: Symbol | undefined, mapper: TypeMapper | undefined): Symbol | undefined { + if (!left || !right) { + return left || right; + } + // A signature `this` type might be a read or a write position... It's very possible that it should be invariant + // and we should refuse to merge signatures if there are `this` types and they do not match. However, so as to be + // permissive when calling, for now, we'll intersect the `this` types just like we do for param types in union signatures. + const thisType = getIntersectionType([getTypeOfSymbol(left), instantiateType(getTypeOfSymbol(right), mapper)]); + return createSymbolWithType(left, thisType); + } + + function combineUnionParameters(left: Signature, right: Signature, mapper: TypeMapper | undefined) { + const leftCount = getParameterCount(left); + const rightCount = getParameterCount(right); + const longest = leftCount >= rightCount ? left : right; + const shorter = longest === left ? right : left; + const longestCount = longest === left ? leftCount : rightCount; + const eitherHasEffectiveRest = hasEffectiveRestParameter(left) || hasEffectiveRestParameter(right); + const needsExtraRestElement = eitherHasEffectiveRest && !hasEffectiveRestParameter(longest); + const params = new Array(longestCount + (needsExtraRestElement ? 1 : 0)); + for (let i = 0; i < longestCount; i++) { + let longestParamType = tryGetTypeAtPosition(longest, i)!; + if (longest === right) { + longestParamType = instantiateType(longestParamType, mapper); + } + let shorterParamType = tryGetTypeAtPosition(shorter, i) || unknownType; + if (shorter === right) { + shorterParamType = instantiateType(shorterParamType, mapper); + } + const unionParamType = getIntersectionType([longestParamType, shorterParamType]); + const isRestParam = eitherHasEffectiveRest && !needsExtraRestElement && i === (longestCount - 1); + const isOptional = i >= getMinArgumentCount(longest) && i >= getMinArgumentCount(shorter); + const leftName = i >= leftCount ? undefined : getParameterNameAtPosition(left, i); + const rightName = i >= rightCount ? undefined : getParameterNameAtPosition(right, i); + + const paramName = leftName === rightName ? leftName : + !leftName ? rightName : + !rightName ? leftName : + undefined; + const paramSymbol = createSymbol( + SymbolFlags.FunctionScopedVariable | (isOptional && !isRestParam ? SymbolFlags.Optional : 0), + paramName || `arg${i}` as __String, + isRestParam ? CheckFlags.RestParameter : isOptional ? CheckFlags.OptionalParameter : 0, + ); + paramSymbol.links.type = isRestParam ? createArrayType(unionParamType) : unionParamType; + params[i] = paramSymbol; + } + if (needsExtraRestElement) { + const restParamSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "args" as __String, CheckFlags.RestParameter); + restParamSymbol.links.type = createArrayType(getTypeAtPosition(shorter, longestCount)); + if (shorter === right) { + restParamSymbol.links.type = instantiateType(restParamSymbol.links.type, mapper); + } + params[longestCount] = restParamSymbol; + } + return params; + } + + function combineSignaturesOfUnionMembers(left: Signature, right: Signature): Signature { + const typeParams = left.typeParameters || right.typeParameters; + let paramMapper: TypeMapper | undefined; + if (left.typeParameters && right.typeParameters) { + paramMapper = createTypeMapper(right.typeParameters, left.typeParameters); + // We just use the type parameter defaults from the first signature + } + const declaration = left.declaration; + const params = combineUnionParameters(left, right, paramMapper); + const thisParam = combineUnionThisParam(left.thisParameter, right.thisParameter, paramMapper); + const minArgCount = Math.max(left.minArgumentCount, right.minArgumentCount); + const result = createSignature( + declaration, + typeParams, + thisParam, + params, + /*resolvedReturnType*/ undefined, + /*resolvedTypePredicate*/ undefined, + minArgCount, + (left.flags | right.flags) & SignatureFlags.PropagatingFlags, + ); + result.compositeKind = TypeFlags.Union; + result.compositeSignatures = concatenate(left.compositeKind !== TypeFlags.Intersection && left.compositeSignatures || [left], [right]); + if (paramMapper) { + result.mapper = left.compositeKind !== TypeFlags.Intersection && left.mapper && left.compositeSignatures ? combineTypeMappers(left.mapper, paramMapper) : paramMapper; + } + else if (left.compositeKind !== TypeFlags.Intersection && left.mapper && left.compositeSignatures) { + result.mapper = left.mapper; + } + return result; + } + + function getUnionIndexInfos(types: readonly Type[]): IndexInfo[] { + const sourceInfos = getIndexInfosOfType(types[0]); + if (sourceInfos) { + const result = []; + for (const info of sourceInfos) { + const indexType = info.keyType; + if (every(types, t => !!getIndexInfoOfType(t, indexType))) { + result.push(createIndexInfo(indexType, getUnionType(map(types, t => getIndexTypeOfType(t, indexType)!)), some(types, t => getIndexInfoOfType(t, indexType)!.isReadonly))); + } + } + return result; + } + return emptyArray; + } + + function resolveUnionTypeMembers(type: UnionType) { + // The members and properties collections are empty for union types. To get all properties of a union + // type use getPropertiesOfType (only the language service uses this). + const callSignatures = getUnionSignatures(map(type.types, t => t === globalFunctionType ? [unknownSignature] : getSignaturesOfType(t, SignatureKind.Call))); + const constructSignatures = getUnionSignatures(map(type.types, t => getSignaturesOfType(t, SignatureKind.Construct))); + const indexInfos = getUnionIndexInfos(type.types); + setStructuredTypeMembers(type, emptySymbols, callSignatures, constructSignatures, indexInfos); + } + + function intersectTypes(type1: Type, type2: Type): Type; + function intersectTypes(type1: Type | undefined, type2: Type | undefined): Type | undefined; + function intersectTypes(type1: Type | undefined, type2: Type | undefined): Type | undefined { + return !type1 ? type2 : !type2 ? type1 : getIntersectionType([type1, type2]); + } + + function findMixins(types: readonly Type[]): readonly boolean[] { + const constructorTypeCount = countWhere(types, t => getSignaturesOfType(t, SignatureKind.Construct).length > 0); + const mixinFlags = map(types, isMixinConstructorType); + if (constructorTypeCount > 0 && constructorTypeCount === countWhere(mixinFlags, b => b)) { + const firstMixinIndex = mixinFlags.indexOf(/*searchElement*/ true); + mixinFlags[firstMixinIndex] = false; + } + return mixinFlags; + } + + function includeMixinType(type: Type, types: readonly Type[], mixinFlags: readonly boolean[], index: number): Type { + const mixedTypes: Type[] = []; + for (let i = 0; i < types.length; i++) { + if (i === index) { + mixedTypes.push(type); + } + else if (mixinFlags[i]) { + mixedTypes.push(getReturnTypeOfSignature(getSignaturesOfType(types[i], SignatureKind.Construct)[0])); + } + } + return getIntersectionType(mixedTypes); + } + + function resolveIntersectionTypeMembers(type: IntersectionType) { + // The members and properties collections are empty for intersection types. To get all properties of an + // intersection type use getPropertiesOfType (only the language service uses this). + let callSignatures: Signature[] | undefined; + let constructSignatures: Signature[] | undefined; + let indexInfos: IndexInfo[] | undefined; + const types = type.types; + const mixinFlags = findMixins(types); + const mixinCount = countWhere(mixinFlags, b => b); + for (let i = 0; i < types.length; i++) { + const t = type.types[i]; + // When an intersection type contains mixin constructor types, the construct signatures from + // those types are discarded and their return types are mixed into the return types of all + // other construct signatures in the intersection type. For example, the intersection type + // '{ new(...args: any[]) => A } & { new(s: string) => B }' has a single construct signature + // 'new(s: string) => A & B'. + if (!mixinFlags[i]) { + let signatures = getSignaturesOfType(t, SignatureKind.Construct); + if (signatures.length && mixinCount > 0) { + signatures = map(signatures, s => { + const clone = cloneSignature(s); + clone.resolvedReturnType = includeMixinType(getReturnTypeOfSignature(s), types, mixinFlags, i); + return clone; + }); + } + constructSignatures = appendSignatures(constructSignatures, signatures); + } + callSignatures = appendSignatures(callSignatures, getSignaturesOfType(t, SignatureKind.Call)); + indexInfos = reduceLeft(getIndexInfosOfType(t), (infos, newInfo) => appendIndexInfo(infos, newInfo, /*union*/ false), indexInfos); + } + setStructuredTypeMembers(type, emptySymbols, callSignatures || emptyArray, constructSignatures || emptyArray, indexInfos || emptyArray); + } + + function appendSignatures(signatures: Signature[] | undefined, newSignatures: readonly Signature[]) { + for (const sig of newSignatures) { + if (!signatures || every(signatures, s => !compareSignaturesIdentical(s, sig, /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false, compareTypesIdentical))) { + signatures = append(signatures, sig); + } + } + return signatures; + } + + function appendIndexInfo(indexInfos: IndexInfo[] | undefined, newInfo: IndexInfo, union: boolean) { + if (indexInfos) { + for (let i = 0; i < indexInfos.length; i++) { + const info = indexInfos[i]; + if (info.keyType === newInfo.keyType) { + indexInfos[i] = createIndexInfo(info.keyType, union ? getUnionType([info.type, newInfo.type]) : getIntersectionType([info.type, newInfo.type]), union ? info.isReadonly || newInfo.isReadonly : info.isReadonly && newInfo.isReadonly); + return indexInfos; + } + } + } + return append(indexInfos, newInfo); + } + + /** + * Converts an AnonymousType to a ResolvedType. + */ + function resolveAnonymousTypeMembers(type: AnonymousType) { + if (type.target) { + setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); + const members = createInstantiatedSymbolTable(getPropertiesOfObjectType(type.target), type.mapper!, /*mappingThisOnly*/ false); + const callSignatures = instantiateSignatures(getSignaturesOfType(type.target, SignatureKind.Call), type.mapper!); + const constructSignatures = instantiateSignatures(getSignaturesOfType(type.target, SignatureKind.Construct), type.mapper!); + const indexInfos = instantiateIndexInfos(getIndexInfosOfType(type.target), type.mapper!); + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + return; + } + const symbol = getMergedSymbol(type.symbol); + if (symbol.flags & SymbolFlags.TypeLiteral) { + setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); + const members = getMembersOfSymbol(symbol); + const callSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.Call)); + const constructSignatures = getSignaturesOfSymbol(members.get(InternalSymbolName.New)); + const indexInfos = getIndexInfosOfSymbol(symbol); + setStructuredTypeMembers(type, members, callSignatures, constructSignatures, indexInfos); + return; + } + // Combinations of function, class, enum and module + let members = getExportsOfSymbol(symbol); + let indexInfos: IndexInfo[] | undefined; + if (symbol === globalThisSymbol) { + const varsOnly = new Map<__String, Symbol>(); + members.forEach(p => { + if (!(p.flags & SymbolFlags.BlockScoped) && !(p.flags & SymbolFlags.ValueModule && p.declarations?.length && every(p.declarations, isAmbientModule))) { + varsOnly.set(p.escapedName, p); + } + }); + members = varsOnly; + } + let baseConstructorIndexInfo: IndexInfo | undefined; + setStructuredTypeMembers(type, members, emptyArray, emptyArray, emptyArray); + if (symbol.flags & SymbolFlags.Class) { + const classType = getDeclaredTypeOfClassOrInterface(symbol); + const baseConstructorType = getBaseConstructorTypeOfClass(classType); + if (baseConstructorType.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.TypeVariable)) { + members = createSymbolTable(getNamedOrIndexSignatureMembers(members)); + addInheritedMembers(members, getPropertiesOfType(baseConstructorType)); + } + else if (baseConstructorType === anyType) { + baseConstructorIndexInfo = createIndexInfo(stringType, anyType, /*isReadonly*/ false); + } + } + + const indexSymbol = getIndexSymbolFromSymbolTable(members); + if (indexSymbol) { + indexInfos = getIndexInfosOfIndexSymbol(indexSymbol); + } + else { + if (baseConstructorIndexInfo) { + indexInfos = append(indexInfos, baseConstructorIndexInfo); + } + if ( + symbol.flags & SymbolFlags.Enum && (getDeclaredTypeOfSymbol(symbol).flags & TypeFlags.Enum || + some(type.properties, prop => !!(getTypeOfSymbol(prop).flags & TypeFlags.NumberLike))) + ) { + indexInfos = append(indexInfos, enumNumberIndexInfo); + } + } + setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos || emptyArray); + // We resolve the members before computing the signatures because a signature may use + // typeof with a qualified name expression that circularly references the type we are + // in the process of resolving (see issue #6072). The temporarily empty signature list + // will never be observed because a qualified name can't reference signatures. + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method)) { + type.callSignatures = getSignaturesOfSymbol(symbol); + } + // And likewise for construct signatures for classes + if (symbol.flags & SymbolFlags.Class) { + const classType = getDeclaredTypeOfClassOrInterface(symbol); + let constructSignatures = symbol.members ? getSignaturesOfSymbol(symbol.members.get(InternalSymbolName.Constructor)) : emptyArray; + if (symbol.flags & SymbolFlags.Function) { + constructSignatures = addRange( + constructSignatures.slice(), + mapDefined( + type.callSignatures, + sig => + isJSConstructor(sig.declaration) ? + createSignature(sig.declaration, sig.typeParameters, sig.thisParameter, sig.parameters, classType, /*resolvedTypePredicate*/ undefined, sig.minArgumentCount, sig.flags & SignatureFlags.PropagatingFlags) : + undefined, + ), + ); + } + if (!constructSignatures.length) { + constructSignatures = getDefaultConstructSignatures(classType); + } + type.constructSignatures = constructSignatures; + } + } + + type ReplaceableIndexedAccessType = IndexedAccessType & { objectType: TypeParameter; indexType: TypeParameter; }; + function replaceIndexedAccess(instantiable: Type, type: ReplaceableIndexedAccessType, replacement: Type) { + // map type.indexType to 0 + // map type.objectType to `[TReplacement]` + // thus making the indexed access `[TReplacement][0]` or `TReplacement` + return instantiateType(instantiable, createTypeMapper([type.indexType, type.objectType], [getNumberLiteralType(0), createTupleType([replacement])])); + } + + // If the original mapped type had an intersection constraint we extract its components, + // and we make an attempt to do so even if the intersection has been reduced to a union. + // This entire process allows us to possibly retrieve the filtering type literals. + // e.g. { [K in keyof U & ("a" | "b") ] } -> "a" | "b" + function getLimitedConstraint(type: ReverseMappedType) { + const constraint = getConstraintTypeFromMappedType(type.mappedType); + if (!(constraint.flags & TypeFlags.Union || constraint.flags & TypeFlags.Intersection)) { + return; + } + const origin = (constraint.flags & TypeFlags.Union) ? (constraint as UnionType).origin : (constraint as IntersectionType); + if (!origin || !(origin.flags & TypeFlags.Intersection)) { + return; + } + const limitedConstraint = getIntersectionType((origin as IntersectionType).types.filter(t => t !== type.constraintType)); + return limitedConstraint !== neverType ? limitedConstraint : undefined; + } + + function resolveReverseMappedTypeMembers(type: ReverseMappedType) { + const indexInfo = getIndexInfoOfType(type.source, stringType); + const modifiers = getMappedTypeModifiers(type.mappedType); + const readonlyMask = modifiers & MappedTypeModifiers.IncludeReadonly ? false : true; + const optionalMask = modifiers & MappedTypeModifiers.IncludeOptional ? 0 : SymbolFlags.Optional; + const indexInfos = indexInfo ? [createIndexInfo(stringType, inferReverseMappedType(indexInfo.type, type.mappedType, type.constraintType) || unknownType, readonlyMask && indexInfo.isReadonly)] : emptyArray; + const members = createSymbolTable(); + const limitedConstraint = getLimitedConstraint(type); + for (const prop of getPropertiesOfType(type.source)) { + // In case of a reverse mapped type with an intersection constraint, if we were able to + // extract the filtering type literals we skip those properties that are not assignable to them, + // because the extra properties wouldn't get through the application of the mapped type anyway + if (limitedConstraint) { + const propertyNameType = getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique); + if (!isTypeAssignableTo(propertyNameType, limitedConstraint)) { + continue; + } + } + const checkFlags = CheckFlags.ReverseMapped | (readonlyMask && isReadonlySymbol(prop) ? CheckFlags.Readonly : 0); + const inferredProp = createSymbol(SymbolFlags.Property | prop.flags & optionalMask, prop.escapedName, checkFlags) as ReverseMappedSymbol; + inferredProp.declarations = prop.declarations; + inferredProp.links.nameType = getSymbolLinks(prop).nameType; + inferredProp.links.propertyType = getTypeOfSymbol(prop); + if ( + type.constraintType.type.flags & TypeFlags.IndexedAccess + && (type.constraintType.type as IndexedAccessType).objectType.flags & TypeFlags.TypeParameter + && (type.constraintType.type as IndexedAccessType).indexType.flags & TypeFlags.TypeParameter + ) { + // A reverse mapping of `{[K in keyof T[K_1]]: T[K_1]}` is the same as that of `{[K in keyof T]: T}`, since all we care about is + // inferring to the "type parameter" (or indexed access) shared by the constraint and template. So, to reduce the number of + // type identities produced, we simplify such indexed access occurences + const newTypeParam = (type.constraintType.type as IndexedAccessType).objectType; + const newMappedType = replaceIndexedAccess(type.mappedType, type.constraintType.type as ReplaceableIndexedAccessType, newTypeParam); + inferredProp.links.mappedType = newMappedType as MappedType; + inferredProp.links.constraintType = getIndexType(newTypeParam) as IndexType; + } + else { + inferredProp.links.mappedType = type.mappedType; + inferredProp.links.constraintType = type.constraintType; + } + members.set(prop.escapedName, inferredProp); + } + setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos); + } + + // Return the lower bound of the key type in a mapped type. Intuitively, the lower + // bound includes those keys that are known to always be present, for example because + // because of constraints on type parameters (e.g. 'keyof T' for a constrained T). + function getLowerBoundOfKeyType(type: Type): Type { + if (type.flags & TypeFlags.Index) { + const t = getApparentType((type as IndexType).type); + return isGenericTupleType(t) ? getKnownKeysOfTupleType(t) : getIndexType(t); + } + if (type.flags & TypeFlags.Conditional) { + if ((type as ConditionalType).root.isDistributive) { + const checkType = (type as ConditionalType).checkType; + const constraint = getLowerBoundOfKeyType(checkType); + if (constraint !== checkType) { + return getConditionalTypeInstantiation(type as ConditionalType, prependTypeMapping((type as ConditionalType).root.checkType, constraint, (type as ConditionalType).mapper), /*forConstraint*/ false); + } + } + return type; + } + if (type.flags & TypeFlags.Union) { + return mapType(type as UnionType, getLowerBoundOfKeyType, /*noReductions*/ true); + } + if (type.flags & TypeFlags.Intersection) { + // Similarly to getTypeFromIntersectionTypeNode, we preserve the special string & {}, number & {}, + // and bigint & {} intersections that are used to prevent subtype reduction in union types. + const types = (type as IntersectionType).types; + if (types.length === 2 && !!(types[0].flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt)) && types[1] === emptyTypeLiteralType) { + return type; + } + return getIntersectionType(sameMap((type as UnionType).types, getLowerBoundOfKeyType)); + } + return type; + } + + function getIsLateCheckFlag(s: Symbol): CheckFlags { + return getCheckFlags(s) & CheckFlags.Late; + } + + function forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(type: Type, include: TypeFlags, stringsOnly: boolean, cb: (keyType: Type) => void) { + for (const prop of getPropertiesOfType(type)) { + cb(getLiteralTypeFromProperty(prop, include)); + } + if (type.flags & TypeFlags.Any) { + cb(stringType); + } + else { + for (const info of getIndexInfosOfType(type)) { + if (!stringsOnly || info.keyType.flags & (TypeFlags.String | TypeFlags.TemplateLiteral)) { + cb(info.keyType); + } + } + } + } + + /** Resolve the members of a mapped type { [P in K]: T } */ + function resolveMappedTypeMembers(type: MappedType) { + const members: SymbolTable = createSymbolTable(); + let indexInfos: IndexInfo[] | undefined; + // Resolve upfront such that recursive references see an empty object type. + setStructuredTypeMembers(type, emptySymbols, emptyArray, emptyArray, emptyArray); + // In { [P in K]: T }, we refer to P as the type parameter type, K as the constraint type, + // and T as the template type. + const typeParameter = getTypeParameterFromMappedType(type); + const constraintType = getConstraintTypeFromMappedType(type); + const mappedType = (type.target as MappedType) || type; + const nameType = getNameTypeFromMappedType(mappedType); + const shouldLinkPropDeclarations = getMappedTypeNameTypeKind(mappedType) !== MappedTypeNameTypeKind.Remapping; + const templateType = getTemplateTypeFromMappedType(mappedType); + const modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T' + const templateModifiers = getMappedTypeModifiers(type); + const include = TypeFlags.StringOrNumberLiteralOrUnique; + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // We have a { [P in keyof T]: X } + forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(modifiersType, include, /*stringsOnly*/ false, addMemberForKeyType); + } + else { + forEachType(getLowerBoundOfKeyType(constraintType), addMemberForKeyType); + } + setStructuredTypeMembers(type, members, emptyArray, emptyArray, indexInfos || emptyArray); + + function addMemberForKeyType(keyType: Type) { + const propNameType = nameType ? instantiateType(nameType, appendTypeMapping(type.mapper, typeParameter, keyType)) : keyType; + forEachType(propNameType, t => addMemberForKeyTypeWorker(keyType, t)); + } + + function addMemberForKeyTypeWorker(keyType: Type, propNameType: Type) { + // If the current iteration type constituent is a string literal type, create a property. + // Otherwise, for type string create a string index signature. + if (isTypeUsableAsPropertyName(propNameType)) { + const propName = getPropertyNameFromType(propNameType); + // String enum members from separate enums with identical values + // are distinct types with the same property name. Make the resulting + // property symbol's name type be the union of those enum member types. + const existingProp = members.get(propName) as MappedSymbol | undefined; + if (existingProp) { + existingProp.links.nameType = getUnionType([existingProp.links.nameType!, propNameType]); + existingProp.links.keyType = getUnionType([existingProp.links.keyType, keyType]); + } + else { + const modifiersProp = isTypeUsableAsPropertyName(keyType) ? getPropertyOfType(modifiersType, getPropertyNameFromType(keyType)) : undefined; + const isOptional = !!(templateModifiers & MappedTypeModifiers.IncludeOptional || + !(templateModifiers & MappedTypeModifiers.ExcludeOptional) && modifiersProp && modifiersProp.flags & SymbolFlags.Optional); + const isReadonly = !!(templateModifiers & MappedTypeModifiers.IncludeReadonly || + !(templateModifiers & MappedTypeModifiers.ExcludeReadonly) && modifiersProp && isReadonlySymbol(modifiersProp)); + const stripOptional = strictNullChecks && !isOptional && modifiersProp && modifiersProp.flags & SymbolFlags.Optional; + const lateFlag: CheckFlags = modifiersProp ? getIsLateCheckFlag(modifiersProp) : 0; + const prop = createSymbol(SymbolFlags.Property | (isOptional ? SymbolFlags.Optional : 0), propName, lateFlag | CheckFlags.Mapped | (isReadonly ? CheckFlags.Readonly : 0) | (stripOptional ? CheckFlags.StripOptional : 0)) as MappedSymbol; + prop.links.mappedType = type; + prop.links.nameType = propNameType; + prop.links.keyType = keyType; + if (modifiersProp) { + prop.links.syntheticOrigin = modifiersProp; + prop.declarations = shouldLinkPropDeclarations ? modifiersProp.declarations : undefined; + } + members.set(propName, prop); + } + } + else if (isValidIndexKeyType(propNameType) || propNameType.flags & (TypeFlags.Any | TypeFlags.Enum)) { + const indexKeyType = propNameType.flags & (TypeFlags.Any | TypeFlags.String) ? stringType : + propNameType.flags & (TypeFlags.Number | TypeFlags.Enum) ? numberType : + propNameType; + const propType = instantiateType(templateType, appendTypeMapping(type.mapper, typeParameter, keyType)); + const modifiersIndexInfo = getApplicableIndexInfo(modifiersType, propNameType); + const isReadonly = !!(templateModifiers & MappedTypeModifiers.IncludeReadonly || + !(templateModifiers & MappedTypeModifiers.ExcludeReadonly) && modifiersIndexInfo?.isReadonly); + const indexInfo = createIndexInfo(indexKeyType, propType, isReadonly); + indexInfos = appendIndexInfo(indexInfos, indexInfo, /*union*/ true); + } + } + } + + function getTypeOfMappedSymbol(symbol: MappedSymbol) { + if (!symbol.links.type) { + const mappedType = symbol.links.mappedType; + if (!pushTypeResolution(symbol, TypeSystemPropertyName.Type)) { + mappedType.containsError = true; + return errorType; + } + const templateType = getTemplateTypeFromMappedType(mappedType.target as MappedType || mappedType); + const mapper = appendTypeMapping(mappedType.mapper, getTypeParameterFromMappedType(mappedType), symbol.links.keyType); + const propType = instantiateType(templateType, mapper); + // When creating an optional property in strictNullChecks mode, if 'undefined' isn't assignable to the + // type, we include 'undefined' in the type. Similarly, when creating a non-optional property in strictNullChecks + // mode, if the underlying property is optional we remove 'undefined' from the type. + let type = strictNullChecks && symbol.flags & SymbolFlags.Optional && !maybeTypeOfKind(propType, TypeFlags.Undefined | TypeFlags.Void) ? getOptionalType(propType, /*isProperty*/ true) : + symbol.links.checkFlags & CheckFlags.StripOptional ? removeMissingOrUndefinedType(propType) : + propType; + if (!popTypeResolution()) { + error(currentNode, Diagnostics.Type_of_property_0_circularly_references_itself_in_mapped_type_1, symbolToString(symbol), typeToString(mappedType)); + type = errorType; + } + symbol.links.type ??= type; + } + return symbol.links.type; + } + + function getTypeParameterFromMappedType(type: MappedType) { + return type.typeParameter || + (type.typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(type.declaration.typeParameter))); + } + + function getConstraintTypeFromMappedType(type: MappedType) { + return type.constraintType || + (type.constraintType = getConstraintOfTypeParameter(getTypeParameterFromMappedType(type)) || errorType); + } + + function getNameTypeFromMappedType(type: MappedType) { + return type.declaration.nameType ? + type.nameType || (type.nameType = instantiateType(getTypeFromTypeNode(type.declaration.nameType), type.mapper)) : + undefined; + } + + function getTemplateTypeFromMappedType(type: MappedType) { + return type.templateType || + (type.templateType = type.declaration.type ? + instantiateType(addOptionality(getTypeFromTypeNode(type.declaration.type), /*isProperty*/ true, !!(getMappedTypeModifiers(type) & MappedTypeModifiers.IncludeOptional)), type.mapper) : + errorType); + } + + function getConstraintDeclarationForMappedType(type: MappedType) { + return getEffectiveConstraintOfTypeParameter(type.declaration.typeParameter); + } + + function isMappedTypeWithKeyofConstraintDeclaration(type: MappedType) { + const constraintDeclaration = getConstraintDeclarationForMappedType(type)!; // TODO: GH#18217 + return constraintDeclaration.kind === SyntaxKind.TypeOperator && + (constraintDeclaration as TypeOperatorNode).operator === SyntaxKind.KeyOfKeyword; + } + + function getModifiersTypeFromMappedType(type: MappedType) { + if (!type.modifiersType) { + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // If the constraint declaration is a 'keyof T' node, the modifiers type is T. We check + // AST nodes here because, when T is a non-generic type, the logic below eagerly resolves + // 'keyof T' to a literal union type and we can't recover T from that type. + type.modifiersType = instantiateType(getTypeFromTypeNode((getConstraintDeclarationForMappedType(type) as TypeOperatorNode).type), type.mapper); + } + else { + // Otherwise, get the declared constraint type, and if the constraint type is a type parameter, + // get the constraint of that type parameter. If the resulting type is an indexed type 'keyof T', + // the modifiers type is T. Otherwise, the modifiers type is unknown. + const declaredType = getTypeFromMappedTypeNode(type.declaration) as MappedType; + const constraint = getConstraintTypeFromMappedType(declaredType); + const extendedConstraint = constraint && constraint.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(constraint as TypeParameter) : constraint; + type.modifiersType = extendedConstraint && extendedConstraint.flags & TypeFlags.Index ? instantiateType((extendedConstraint as IndexType).type, type.mapper) : unknownType; + } + } + return type.modifiersType; + } + + function getMappedTypeModifiers(type: MappedType): MappedTypeModifiers { + const declaration = type.declaration; + return (declaration.readonlyToken ? declaration.readonlyToken.kind === SyntaxKind.MinusToken ? MappedTypeModifiers.ExcludeReadonly : MappedTypeModifiers.IncludeReadonly : 0) | + (declaration.questionToken ? declaration.questionToken.kind === SyntaxKind.MinusToken ? MappedTypeModifiers.ExcludeOptional : MappedTypeModifiers.IncludeOptional : 0); + } + + // Return -1, 0, or 1, where -1 means optionality is stripped (i.e. -?), 0 means optionality is unchanged, and 1 means + // optionality is added (i.e. +?). + function getMappedTypeOptionality(type: MappedType): number { + const modifiers = getMappedTypeModifiers(type); + return modifiers & MappedTypeModifiers.ExcludeOptional ? -1 : modifiers & MappedTypeModifiers.IncludeOptional ? 1 : 0; + } + + // Return -1, 0, or 1, for stripped, unchanged, or added optionality respectively. When a homomorphic mapped type doesn't + // modify optionality, recursively consult the optionality of the type being mapped over to see if it strips or adds optionality. + // For intersections, return -1 or 1 when all constituents strip or add optionality, otherwise return 0. + function getCombinedMappedTypeOptionality(type: Type): number { + if (getObjectFlags(type) & ObjectFlags.Mapped) { + return getMappedTypeOptionality(type as MappedType) || getCombinedMappedTypeOptionality(getModifiersTypeFromMappedType(type as MappedType)); + } + if (type.flags & TypeFlags.Intersection) { + const optionality = getCombinedMappedTypeOptionality((type as IntersectionType).types[0]); + return every((type as IntersectionType).types, (t, i) => i === 0 || getCombinedMappedTypeOptionality(t) === optionality) ? optionality : 0; + } + return 0; + } + + function isPartialMappedType(type: Type) { + return !!(getObjectFlags(type) & ObjectFlags.Mapped && getMappedTypeModifiers(type as MappedType) & MappedTypeModifiers.IncludeOptional); + } + + function isGenericMappedType(type: Type): type is MappedType { + if (getObjectFlags(type) & ObjectFlags.Mapped) { + const constraint = getConstraintTypeFromMappedType(type as MappedType); + if (isGenericIndexType(constraint)) { + return true; + } + // A mapped type is generic if the 'as' clause references generic types other than the iteration type. + // To determine this, we substitute the constraint type (that we now know isn't generic) for the iteration + // type and check whether the resulting type is generic. + const nameType = getNameTypeFromMappedType(type as MappedType); + if (nameType && isGenericIndexType(instantiateType(nameType, makeUnaryTypeMapper(getTypeParameterFromMappedType(type as MappedType), constraint)))) { + return true; + } + } + return false; + } + + function getMappedTypeNameTypeKind(type: MappedType): MappedTypeNameTypeKind { + const nameType = getNameTypeFromMappedType(type); + if (!nameType) { + return MappedTypeNameTypeKind.None; + } + return isTypeAssignableTo(nameType, getTypeParameterFromMappedType(type)) ? MappedTypeNameTypeKind.Filtering : MappedTypeNameTypeKind.Remapping; + } + + function resolveStructuredTypeMembers(type: StructuredType): ResolvedType { + if (!(type as ResolvedType).members) { + if (type.flags & TypeFlags.Object) { + if ((type as ObjectType).objectFlags & ObjectFlags.Reference) { + resolveTypeReferenceMembers(type as TypeReference); + } + else if ((type as ObjectType).objectFlags & ObjectFlags.ClassOrInterface) { + resolveClassOrInterfaceMembers(type as InterfaceType); + } + else if ((type as ReverseMappedType).objectFlags & ObjectFlags.ReverseMapped) { + resolveReverseMappedTypeMembers(type as ReverseMappedType); + } + else if ((type as ObjectType).objectFlags & ObjectFlags.Anonymous) { + resolveAnonymousTypeMembers(type as AnonymousType); + } + else if ((type as MappedType).objectFlags & ObjectFlags.Mapped) { + resolveMappedTypeMembers(type as MappedType); + } + else { + Debug.fail("Unhandled object type " + Debug.formatObjectFlags(type.objectFlags)); + } + } + else if (type.flags & TypeFlags.Union) { + resolveUnionTypeMembers(type as UnionType); + } + else if (type.flags & TypeFlags.Intersection) { + resolveIntersectionTypeMembers(type as IntersectionType); + } + else { + Debug.fail("Unhandled type " + Debug.formatTypeFlags(type.flags)); + } + } + return type as ResolvedType; + } + + /** Return properties of an object type or an empty array for other types */ + function getPropertiesOfObjectType(type: Type): Symbol[] { + if (type.flags & TypeFlags.Object) { + return resolveStructuredTypeMembers(type as ObjectType).properties; + } + return emptyArray; + } + + /** If the given type is an object type and that type has a property by the given name, + * return the symbol for that property. Otherwise return undefined. + */ + function getPropertyOfObjectType(type: Type, name: __String): Symbol | undefined { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + const symbol = resolved.members.get(name); + if (symbol && symbolIsValue(symbol)) { + return symbol; + } + } + } + + function getPropertiesOfUnionOrIntersectionType(type: UnionOrIntersectionType): Symbol[] { + if (!type.resolvedProperties) { + const members = createSymbolTable(); + for (const current of type.types) { + for (const prop of getPropertiesOfType(current)) { + if (!members.has(prop.escapedName)) { + const combinedProp = getPropertyOfUnionOrIntersectionType(type, prop.escapedName, /*skipObjectFunctionPropertyAugment*/ !!(type.flags & TypeFlags.Intersection)); + if (combinedProp) { + members.set(prop.escapedName, combinedProp); + } + } + } + // The properties of a union type are those that are present in all constituent types, so + // we only need to check the properties of the first type without index signature + if (type.flags & TypeFlags.Union && getIndexInfosOfType(current).length === 0) { + break; + } + } + type.resolvedProperties = getNamedMembers(members); + } + return type.resolvedProperties; + } + + function getPropertiesOfType(type: Type): Symbol[] { + type = getReducedApparentType(type); + return type.flags & TypeFlags.UnionOrIntersection ? + getPropertiesOfUnionOrIntersectionType(type as UnionType) : + getPropertiesOfObjectType(type); + } + + function forEachPropertyOfType(type: Type, action: (symbol: Symbol, escapedName: __String) => void): void { + type = getReducedApparentType(type); + if (type.flags & TypeFlags.StructuredType) { + resolveStructuredTypeMembers(type as StructuredType).members.forEach((symbol, escapedName) => { + if (isNamedMember(symbol, escapedName)) { + action(symbol, escapedName); + } + }); + } + } + + function isTypeInvalidDueToUnionDiscriminant(contextualType: Type, obj: ObjectLiteralExpression | JsxAttributes): boolean { + const list = obj.properties as NodeArray; + return list.some(property => { + const nameType = property.name && (isJsxNamespacedName(property.name) ? getStringLiteralType(getTextOfJsxAttributeName(property.name)) : getLiteralTypeFromPropertyName(property.name)); + const name = nameType && isTypeUsableAsPropertyName(nameType) ? getPropertyNameFromType(nameType) : undefined; + const expected = name === undefined ? undefined : getTypeOfPropertyOfType(contextualType, name); + return !!expected && isLiteralType(expected) && !isTypeAssignableTo(getTypeOfNode(property), expected); + }); + } + + function getAllPossiblePropertiesOfTypes(types: readonly Type[]): Symbol[] { + const unionType = getUnionType(types); + if (!(unionType.flags & TypeFlags.Union)) { + return getAugmentedPropertiesOfType(unionType); + } + + const props = createSymbolTable(); + for (const memberType of types) { + for (const { escapedName } of getAugmentedPropertiesOfType(memberType)) { + if (!props.has(escapedName)) { + const prop = createUnionOrIntersectionProperty(unionType as UnionType, escapedName); + // May be undefined if the property is private + if (prop) props.set(escapedName, prop); + } + } + } + return arrayFrom(props.values()); + } + + function getConstraintOfType(type: InstantiableType | UnionOrIntersectionType): Type | undefined { + return type.flags & TypeFlags.TypeParameter ? getConstraintOfTypeParameter(type as TypeParameter) : + type.flags & TypeFlags.IndexedAccess ? getConstraintOfIndexedAccess(type as IndexedAccessType) : + type.flags & TypeFlags.Conditional ? getConstraintOfConditionalType(type as ConditionalType) : + getBaseConstraintOfType(type); + } + + function getConstraintOfTypeParameter(typeParameter: TypeParameter): Type | undefined { + return hasNonCircularBaseConstraint(typeParameter) ? getConstraintFromTypeParameter(typeParameter) : undefined; + } + + function isConstMappedType(type: MappedType, depth: number): boolean { + const typeVariable = getHomomorphicTypeVariable(type); + return !!typeVariable && isConstTypeVariable(typeVariable, depth); + } + + function isConstTypeVariable(type: Type | undefined, depth = 0): boolean { + return depth < 5 && !!(type && ( + type.flags & TypeFlags.TypeParameter && some((type as TypeParameter).symbol?.declarations, d => hasSyntacticModifier(d, ModifierFlags.Const)) || + type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, t => isConstTypeVariable(t, depth)) || + type.flags & TypeFlags.IndexedAccess && isConstTypeVariable((type as IndexedAccessType).objectType, depth + 1) || + type.flags & TypeFlags.Conditional && isConstTypeVariable(getConstraintOfConditionalType(type as ConditionalType), depth + 1) || + type.flags & TypeFlags.Substitution && isConstTypeVariable((type as SubstitutionType).baseType, depth) || + getObjectFlags(type) & ObjectFlags.Mapped && isConstMappedType(type as MappedType, depth) || + isGenericTupleType(type) && findIndex(getElementTypes(type), (t, i) => !!(type.target.elementFlags[i] & ElementFlags.Variadic) && isConstTypeVariable(t, depth)) >= 0 + )); + } + + function getConstraintOfIndexedAccess(type: IndexedAccessType) { + return hasNonCircularBaseConstraint(type) ? getConstraintFromIndexedAccess(type) : undefined; + } + + function getSimplifiedTypeOrConstraint(type: Type) { + const simplified = getSimplifiedType(type, /*writing*/ false); + return simplified !== type ? simplified : getConstraintOfType(type); + } + + function getConstraintFromIndexedAccess(type: IndexedAccessType) { + if (isMappedTypeGenericIndexedAccess(type)) { + // For indexed access types of the form { [P in K]: E }[X], where K is non-generic and X is generic, + // we substitute an instantiation of E where P is replaced with X. + return substituteIndexedMappedType(type.objectType as MappedType, type.indexType); + } + const indexConstraint = getSimplifiedTypeOrConstraint(type.indexType); + if (indexConstraint && indexConstraint !== type.indexType) { + const indexedAccess = getIndexedAccessTypeOrUndefined(type.objectType, indexConstraint, type.accessFlags); + if (indexedAccess) { + return indexedAccess; + } + } + const objectConstraint = getSimplifiedTypeOrConstraint(type.objectType); + if (objectConstraint && objectConstraint !== type.objectType) { + return getIndexedAccessTypeOrUndefined(objectConstraint, type.indexType, type.accessFlags); + } + return undefined; + } + + function getDefaultConstraintOfConditionalType(type: ConditionalType) { + if (!type.resolvedDefaultConstraint) { + // An `any` branch of a conditional type would normally be viral - specifically, without special handling here, + // a conditional type with a single branch of type `any` would be assignable to anything, since it's constraint would simplify to + // just `any`. This result is _usually_ unwanted - so instead here we elide an `any` branch from the constraint type, + // in effect treating `any` like `never` rather than `unknown` in this location. + const trueConstraint = getInferredTrueTypeFromConditionalType(type); + const falseConstraint = getFalseTypeFromConditionalType(type); + type.resolvedDefaultConstraint = isTypeAny(trueConstraint) ? falseConstraint : isTypeAny(falseConstraint) ? trueConstraint : getUnionType([trueConstraint, falseConstraint]); + } + return type.resolvedDefaultConstraint; + } + + function getConstraintOfDistributiveConditionalType(type: ConditionalType): Type | undefined { + if (type.resolvedConstraintOfDistributive !== undefined) { + return type.resolvedConstraintOfDistributive || undefined; + } + + // Check if we have a conditional type of the form 'T extends U ? X : Y', where T is a constrained + // type parameter. If so, create an instantiation of the conditional type where T is replaced + // with its constraint. We do this because if the constraint is a union type it will be distributed + // over the conditional type and possibly reduced. For example, 'T extends undefined ? never : T' + // removes 'undefined' from T. + // We skip returning a distributive constraint for a restrictive instantiation of a conditional type + // as the constraint for all type params (check type included) have been replace with `unknown`, which + // is going to produce even more false positive/negative results than the distribute constraint already does. + // Please note: the distributive constraint is a kludge for emulating what a negated type could to do filter + // a union - once negated types exist and are applied to the conditional false branch, this "constraint" + // likely doesn't need to exist. + if (type.root.isDistributive && type.restrictiveInstantiation !== type) { + const simplified = getSimplifiedType(type.checkType, /*writing*/ false); + const constraint = simplified === type.checkType ? getConstraintOfType(simplified) : simplified; + if (constraint && constraint !== type.checkType) { + const instantiated = getConditionalTypeInstantiation(type, prependTypeMapping(type.root.checkType, constraint, type.mapper), /*forConstraint*/ true); + if (!(instantiated.flags & TypeFlags.Never)) { + type.resolvedConstraintOfDistributive = instantiated; + return instantiated; + } + } + } + type.resolvedConstraintOfDistributive = false; + return undefined; + } + + function getConstraintFromConditionalType(type: ConditionalType) { + return getConstraintOfDistributiveConditionalType(type) || getDefaultConstraintOfConditionalType(type); + } + + function getConstraintOfConditionalType(type: ConditionalType) { + return hasNonCircularBaseConstraint(type) ? getConstraintFromConditionalType(type) : undefined; + } + + function getEffectiveConstraintOfIntersection(types: readonly Type[], targetIsUnion: boolean) { + let constraints: Type[] | undefined; + let hasDisjointDomainType = false; + for (const t of types) { + if (t.flags & TypeFlags.Instantiable) { + // We keep following constraints as long as we have an instantiable type that is known + // not to be circular or infinite (hence we stop on index access types). + let constraint = getConstraintOfType(t); + while (constraint && constraint.flags & (TypeFlags.TypeParameter | TypeFlags.Index | TypeFlags.Conditional)) { + constraint = getConstraintOfType(constraint); + } + if (constraint) { + constraints = append(constraints, constraint); + if (targetIsUnion) { + constraints = append(constraints, t); + } + } + } + else if (t.flags & TypeFlags.DisjointDomains || isEmptyAnonymousObjectType(t)) { + hasDisjointDomainType = true; + } + } + // If the target is a union type or if we are intersecting with types belonging to one of the + // disjoint domains, we may end up producing a constraint that hasn't been examined before. + if (constraints && (targetIsUnion || hasDisjointDomainType)) { + if (hasDisjointDomainType) { + // We add any types belong to one of the disjoint domains because they might cause the final + // intersection operation to reduce the union constraints. + for (const t of types) { + if (t.flags & TypeFlags.DisjointDomains || isEmptyAnonymousObjectType(t)) { + constraints = append(constraints, t); + } + } + } + // The source types were normalized; ensure the result is normalized too. + return getNormalizedType(getIntersectionType(constraints, IntersectionFlags.NoConstraintReduction), /*writing*/ false); + } + return undefined; + } + + function getBaseConstraintOfType(type: Type): Type | undefined { + if (type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.UnionOrIntersection | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || isGenericTupleType(type)) { + const constraint = getResolvedBaseConstraint(type as InstantiableType | UnionOrIntersectionType); + return constraint !== noConstraintType && constraint !== circularConstraintType ? constraint : undefined; + } + return type.flags & TypeFlags.Index ? stringNumberSymbolType : undefined; + } + + /** + * This is similar to `getBaseConstraintOfType` except it returns the input type if there's no base constraint, instead of `undefined` + * It also doesn't map indexes to `string`, as where this is used this would be unneeded (and likely undesirable) + */ + function getBaseConstraintOrType(type: Type) { + return getBaseConstraintOfType(type) || type; + } + + function hasNonCircularBaseConstraint(type: InstantiableType): boolean { + return getResolvedBaseConstraint(type) !== circularConstraintType; + } + + /** + * Return the resolved base constraint of a type variable. The noConstraintType singleton is returned if the + * type variable has no constraint, and the circularConstraintType singleton is returned if the constraint + * circularly references the type variable. + */ + function getResolvedBaseConstraint(type: InstantiableType | UnionOrIntersectionType): Type { + if (type.resolvedBaseConstraint) { + return type.resolvedBaseConstraint; + } + const stack: object[] = []; + return type.resolvedBaseConstraint = getImmediateBaseConstraint(type); + + function getImmediateBaseConstraint(t: Type): Type { + if (!t.immediateBaseConstraint) { + if (!pushTypeResolution(t, TypeSystemPropertyName.ImmediateBaseConstraint)) { + return circularConstraintType; + } + let result; + // We always explore at least 10 levels of nested constraints. Thereafter, we continue to explore + // up to 50 levels of nested constraints provided there are no "deeply nested" types on the stack + // (i.e. no types for which five instantiations have been recorded on the stack). If we reach 50 + // levels of nesting, we are presumably exploring a repeating pattern with a long cycle that hasn't + // yet triggered the deeply nested limiter. We have no test cases that actually get to 50 levels of + // nesting, so it is effectively just a safety stop. + const identity = getRecursionIdentity(t); + if (stack.length < 10 || stack.length < 50 && !contains(stack, identity)) { + stack.push(identity); + result = computeBaseConstraint(getSimplifiedType(t, /*writing*/ false)); + stack.pop(); + } + if (!popTypeResolution()) { + if (t.flags & TypeFlags.TypeParameter) { + const errorNode = getConstraintDeclaration(t as TypeParameter); + if (errorNode) { + const diagnostic = error(errorNode, Diagnostics.Type_parameter_0_has_a_circular_constraint, typeToString(t)); + if (currentNode && !isNodeDescendantOf(errorNode, currentNode) && !isNodeDescendantOf(currentNode, errorNode)) { + addRelatedInfo(diagnostic, createDiagnosticForNode(currentNode, Diagnostics.Circularity_originates_in_type_at_this_location)); + } + } + } + result = circularConstraintType; + } + t.immediateBaseConstraint ??= result || noConstraintType; + } + return t.immediateBaseConstraint; + } + + function getBaseConstraint(t: Type): Type | undefined { + const c = getImmediateBaseConstraint(t); + return c !== noConstraintType && c !== circularConstraintType ? c : undefined; + } + + function computeBaseConstraint(t: Type): Type | undefined { + if (t.flags & TypeFlags.TypeParameter) { + const constraint = getConstraintFromTypeParameter(t as TypeParameter); + return (t as TypeParameter).isThisType || !constraint ? + constraint : + getBaseConstraint(constraint); + } + if (t.flags & TypeFlags.UnionOrIntersection) { + const types = (t as UnionOrIntersectionType).types; + const baseTypes: Type[] = []; + let different = false; + for (const type of types) { + const baseType = getBaseConstraint(type); + if (baseType) { + if (baseType !== type) { + different = true; + } + baseTypes.push(baseType); + } + else { + different = true; + } + } + if (!different) { + return t; + } + return t.flags & TypeFlags.Union && baseTypes.length === types.length ? getUnionType(baseTypes) : + t.flags & TypeFlags.Intersection && baseTypes.length ? getIntersectionType(baseTypes) : + undefined; + } + if (t.flags & TypeFlags.Index) { + return stringNumberSymbolType; + } + if (t.flags & TypeFlags.TemplateLiteral) { + const types = (t as TemplateLiteralType).types; + const constraints = mapDefined(types, getBaseConstraint); + return constraints.length === types.length ? getTemplateLiteralType((t as TemplateLiteralType).texts, constraints) : stringType; + } + if (t.flags & TypeFlags.StringMapping) { + const constraint = getBaseConstraint((t as StringMappingType).type); + return constraint && constraint !== (t as StringMappingType).type ? getStringMappingType((t as StringMappingType).symbol, constraint) : stringType; + } + if (t.flags & TypeFlags.IndexedAccess) { + if (isMappedTypeGenericIndexedAccess(t)) { + // For indexed access types of the form { [P in K]: E }[X], where K is non-generic and X is generic, + // we substitute an instantiation of E where P is replaced with X. + return getBaseConstraint(substituteIndexedMappedType((t as IndexedAccessType).objectType as MappedType, (t as IndexedAccessType).indexType)); + } + const baseObjectType = getBaseConstraint((t as IndexedAccessType).objectType); + const baseIndexType = getBaseConstraint((t as IndexedAccessType).indexType); + const baseIndexedAccess = baseObjectType && baseIndexType && getIndexedAccessTypeOrUndefined(baseObjectType, baseIndexType, (t as IndexedAccessType).accessFlags); + return baseIndexedAccess && getBaseConstraint(baseIndexedAccess); + } + if (t.flags & TypeFlags.Conditional) { + const constraint = getConstraintFromConditionalType(t as ConditionalType); + return constraint && getBaseConstraint(constraint); + } + if (t.flags & TypeFlags.Substitution) { + return getBaseConstraint(getSubstitutionIntersection(t as SubstitutionType)); + } + if (isGenericTupleType(t)) { + // We substitute constraints for variadic elements only when the constraints are array types or + // non-variadic tuple types as we want to avoid further (possibly unbounded) recursion. + const newElements = map(getElementTypes(t), (v, i) => { + const constraint = v.flags & TypeFlags.TypeParameter && t.target.elementFlags[i] & ElementFlags.Variadic && getBaseConstraint(v) || v; + return constraint !== v && everyType(constraint, c => isArrayOrTupleType(c) && !isGenericTupleType(c)) ? constraint : v; + }); + return createTupleType(newElements, t.target.elementFlags, t.target.readonly, t.target.labeledElementDeclarations); + } + return t; + } + } + + function getApparentTypeOfIntersectionType(type: IntersectionType, thisArgument: Type) { + if (type === thisArgument) { + return type.resolvedApparentType || (type.resolvedApparentType = getTypeWithThisArgument(type, thisArgument, /*needApparentType*/ true)); + } + const key = `I${getTypeId(type)},${getTypeId(thisArgument)}`; + return getCachedType(key) ?? setCachedType(key, getTypeWithThisArgument(type, thisArgument, /*needApparentType*/ true)); + } + + function getResolvedTypeParameterDefault(typeParameter: TypeParameter): Type | undefined { + if (!typeParameter.default) { + if (typeParameter.target) { + const targetDefault = getResolvedTypeParameterDefault(typeParameter.target); + typeParameter.default = targetDefault ? instantiateType(targetDefault, typeParameter.mapper) : noConstraintType; + } + else { + // To block recursion, set the initial value to the resolvingDefaultType. + typeParameter.default = resolvingDefaultType; + const defaultDeclaration = typeParameter.symbol && forEach(typeParameter.symbol.declarations, decl => isTypeParameterDeclaration(decl) && decl.default); + const defaultType = defaultDeclaration ? getTypeFromTypeNode(defaultDeclaration) : noConstraintType; + if (typeParameter.default === resolvingDefaultType) { + // If we have not been called recursively, set the correct default type. + typeParameter.default = defaultType; + } + } + } + else if (typeParameter.default === resolvingDefaultType) { + // If we are called recursively for this type parameter, mark the default as circular. + typeParameter.default = circularConstraintType; + } + return typeParameter.default; + } + + /** + * Gets the default type for a type parameter. + * + * If the type parameter is the result of an instantiation, this gets the instantiated + * default type of its target. If the type parameter has no default type or the default is + * circular, `undefined` is returned. + */ + function getDefaultFromTypeParameter(typeParameter: TypeParameter): Type | undefined { + const defaultType = getResolvedTypeParameterDefault(typeParameter); + return defaultType !== noConstraintType && defaultType !== circularConstraintType ? defaultType : undefined; + } + + function hasNonCircularTypeParameterDefault(typeParameter: TypeParameter) { + return getResolvedTypeParameterDefault(typeParameter) !== circularConstraintType; + } + + /** + * Indicates whether the declaration of a typeParameter has a default type. + */ + function hasTypeParameterDefault(typeParameter: TypeParameter): boolean { + return !!(typeParameter.symbol && forEach(typeParameter.symbol.declarations, decl => isTypeParameterDeclaration(decl) && decl.default)); + } + + function getApparentTypeOfMappedType(type: MappedType) { + return type.resolvedApparentType || (type.resolvedApparentType = getResolvedApparentTypeOfMappedType(type)); + } + + function getResolvedApparentTypeOfMappedType(type: MappedType): Type { + const target = (type.target ?? type) as MappedType; + const typeVariable = getHomomorphicTypeVariable(target); + if (typeVariable && !target.declaration.nameType) { + // We have a homomorphic mapped type or an instantiation of a homomorphic mapped type, i.e. a type + // of the form { [P in keyof T]: X }. Obtain the modifiers type (the T of the keyof T), and if it is + // another generic mapped type, recursively obtain its apparent type. Otherwise, obtain its base + // constraint. Then, if every constituent of the base constraint is an array or tuple type, apply + // this mapped type to the base constraint. It is safe to recurse when the modifiers type is a + // mapped type because we protect again circular constraints in getTypeFromMappedTypeNode. + const modifiersType = getModifiersTypeFromMappedType(type); + const baseConstraint = isGenericMappedType(modifiersType) ? getApparentTypeOfMappedType(modifiersType) : getBaseConstraintOfType(modifiersType); + if (baseConstraint && everyType(baseConstraint, t => isArrayOrTupleType(t) || isArrayOrTupleOrIntersection(t))) { + return instantiateType(target, prependTypeMapping(typeVariable, baseConstraint, type.mapper)); + } + } + return type; + } + + function isArrayOrTupleOrIntersection(type: Type) { + return !!(type.flags & TypeFlags.Intersection) && every((type as IntersectionType).types, isArrayOrTupleType); + } + + function isMappedTypeGenericIndexedAccess(type: Type) { + let objectType; + return !!(type.flags & TypeFlags.IndexedAccess && getObjectFlags(objectType = (type as IndexedAccessType).objectType) & ObjectFlags.Mapped && + !isGenericMappedType(objectType) && isGenericIndexType((type as IndexedAccessType).indexType) && + !(getMappedTypeModifiers(objectType as MappedType) & MappedTypeModifiers.ExcludeOptional) && !(objectType as MappedType).declaration.nameType); + } + + /** + * For a type parameter, return the base constraint of the type parameter. For the string, number, + * boolean, and symbol primitive types, return the corresponding object types. Otherwise return the + * type itself. + */ + function getApparentType(type: Type): Type { + const t = type.flags & TypeFlags.Instantiable ? getBaseConstraintOfType(type) || unknownType : type; + const objectFlags = getObjectFlags(t); + return objectFlags & ObjectFlags.Mapped ? getApparentTypeOfMappedType(t as MappedType) : + objectFlags & ObjectFlags.Reference && t !== type ? getTypeWithThisArgument(t, type) : + t.flags & TypeFlags.Intersection ? getApparentTypeOfIntersectionType(t as IntersectionType, type) : + t.flags & TypeFlags.StringLike ? globalStringType : + t.flags & TypeFlags.NumberLike ? globalNumberType : + t.flags & TypeFlags.BigIntLike ? getGlobalBigIntType() : + t.flags & TypeFlags.BooleanLike ? globalBooleanType : + t.flags & TypeFlags.ESSymbolLike ? getGlobalESSymbolType() : + t.flags & TypeFlags.NonPrimitive ? emptyObjectType : + t.flags & TypeFlags.Index ? stringNumberSymbolType : + t.flags & TypeFlags.Unknown && !strictNullChecks ? emptyObjectType : + t; + } + + function getReducedApparentType(type: Type): Type { + // Since getApparentType may return a non-reduced union or intersection type, we need to perform + // type reduction both before and after obtaining the apparent type. For example, given a type parameter + // 'T extends A | B', the type 'T & X' becomes 'A & X | B & X' after obtaining the apparent type, and + // that type may need further reduction to remove empty intersections. + return getReducedType(getApparentType(getReducedType(type))); + } + + function createUnionOrIntersectionProperty(containingType: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { + let singleProp: Symbol | undefined; + let propSet: Map | undefined; + let indexTypes: Type[] | undefined; + const isUnion = containingType.flags & TypeFlags.Union; + // Flags we want to propagate to the result if they exist in all source symbols + let optionalFlag: SymbolFlags | undefined; + let syntheticFlag = CheckFlags.SyntheticMethod; + let checkFlags = isUnion ? 0 : CheckFlags.Readonly; + let mergedInstantiations = false; + for (const current of containingType.types) { + const type = getApparentType(current); + if (!(isErrorType(type) || type.flags & TypeFlags.Never)) { + const prop = getPropertyOfType(type, name, skipObjectFunctionPropertyAugment); + const modifiers = prop ? getDeclarationModifierFlagsFromSymbol(prop) : 0; + if (prop) { + if (prop.flags & SymbolFlags.ClassMember) { + optionalFlag ??= isUnion ? SymbolFlags.None : SymbolFlags.Optional; + if (isUnion) { + optionalFlag |= prop.flags & SymbolFlags.Optional; + } + else { + optionalFlag &= prop.flags; + } + } + if (!singleProp) { + singleProp = prop; + } + else if (prop !== singleProp) { + const isInstantiation = (getTargetSymbol(prop) || prop) === (getTargetSymbol(singleProp) || singleProp); + // If the symbols are instances of one another with identical types - consider the symbols + // equivalent and just use the first one, which thus allows us to avoid eliding private + // members when intersecting a (this-)instantiations of a class with its raw base or another instance + if (isInstantiation && compareProperties(singleProp, prop, (a, b) => a === b ? Ternary.True : Ternary.False) === Ternary.True) { + // If we merged instantiations of a generic type, we replicate the symbol parent resetting behavior we used + // to do when we recorded multiple distinct symbols so that we still get, eg, `Array.length` printed + // back and not `Array.length` when we're looking at a `.length` access on a `string[] | number[]` + mergedInstantiations = !!singleProp.parent && !!length(getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(singleProp.parent)); + } + else { + if (!propSet) { + propSet = new Map(); + propSet.set(getSymbolId(singleProp), singleProp); + } + const id = getSymbolId(prop); + if (!propSet.has(id)) { + propSet.set(id, prop); + } + } + } + if (isUnion && isReadonlySymbol(prop)) { + checkFlags |= CheckFlags.Readonly; + } + else if (!isUnion && !isReadonlySymbol(prop)) { + checkFlags &= ~CheckFlags.Readonly; + } + checkFlags |= (!(modifiers & ModifierFlags.NonPublicAccessibilityModifier) ? CheckFlags.ContainsPublic : 0) | + (modifiers & ModifierFlags.Protected ? CheckFlags.ContainsProtected : 0) | + (modifiers & ModifierFlags.Private ? CheckFlags.ContainsPrivate : 0) | + (modifiers & ModifierFlags.Static ? CheckFlags.ContainsStatic : 0); + if (!isPrototypeProperty(prop)) { + syntheticFlag = CheckFlags.SyntheticProperty; + } + } + else if (isUnion) { + const indexInfo = !isLateBoundName(name) && getApplicableIndexInfoForName(type, name); + if (indexInfo) { + checkFlags |= CheckFlags.WritePartial | (indexInfo.isReadonly ? CheckFlags.Readonly : 0); + indexTypes = append(indexTypes, isTupleType(type) ? getRestTypeOfTupleType(type) || undefinedType : indexInfo.type); + } + else if (isObjectLiteralType(type) && !(getObjectFlags(type) & ObjectFlags.ContainsSpread)) { + checkFlags |= CheckFlags.WritePartial; + indexTypes = append(indexTypes, undefinedType); + } + else { + checkFlags |= CheckFlags.ReadPartial; + } + } + } + } + if ( + !singleProp || + isUnion && + (propSet || checkFlags & CheckFlags.Partial) && + checkFlags & (CheckFlags.ContainsPrivate | CheckFlags.ContainsProtected) && + !(propSet && getCommonDeclarationsOfSymbols(propSet.values())) + ) { + // No property was found, or, in a union, a property has a private or protected declaration in one + // constituent, but is missing or has a different declaration in another constituent. + return undefined; + } + if (!propSet && !(checkFlags & CheckFlags.ReadPartial) && !indexTypes) { + if (mergedInstantiations) { + // No symbol from a union/intersection should have a `.parent` set (since unions/intersections don't act as symbol parents) + // Unless that parent is "reconstituted" from the "first value declaration" on the symbol (which is likely different than its instantiated parent!) + // They also have a `.containingType` set, which affects some services endpoints behavior, like `getRootSymbol` + const links = tryCast(singleProp, isTransientSymbol)?.links; + const clone = createSymbolWithType(singleProp, links?.type); + clone.parent = singleProp.valueDeclaration?.symbol?.parent; + clone.links.containingType = containingType; + clone.links.mapper = links?.mapper; + clone.links.writeType = getWriteTypeOfSymbol(singleProp); + return clone; + } + else { + return singleProp; + } + } + const props = propSet ? arrayFrom(propSet.values()) : [singleProp]; + let declarations: Declaration[] | undefined; + let firstType: Type | undefined; + let nameType: Type | undefined; + const propTypes: Type[] = []; + let writeTypes: Type[] | undefined; + let firstValueDeclaration: Declaration | undefined; + let hasNonUniformValueDeclaration = false; + for (const prop of props) { + if (!firstValueDeclaration) { + firstValueDeclaration = prop.valueDeclaration; + } + else if (prop.valueDeclaration && prop.valueDeclaration !== firstValueDeclaration) { + hasNonUniformValueDeclaration = true; + } + declarations = addRange(declarations, prop.declarations); + const type = getTypeOfSymbol(prop); + if (!firstType) { + firstType = type; + nameType = getSymbolLinks(prop).nameType; + } + const writeType = getWriteTypeOfSymbol(prop); + if (writeTypes || writeType !== type) { + writeTypes = append(!writeTypes ? propTypes.slice() : writeTypes, writeType); + } + if (type !== firstType) { + checkFlags |= CheckFlags.HasNonUniformType; + } + if (isLiteralType(type) || isPatternLiteralType(type)) { + checkFlags |= CheckFlags.HasLiteralType; + } + if (type.flags & TypeFlags.Never && type !== uniqueLiteralType) { + checkFlags |= CheckFlags.HasNeverType; + } + propTypes.push(type); + } + addRange(propTypes, indexTypes); + const result = createSymbol(SymbolFlags.Property | (optionalFlag ?? 0), name, syntheticFlag | checkFlags); + result.links.containingType = containingType; + if (!hasNonUniformValueDeclaration && firstValueDeclaration) { + result.valueDeclaration = firstValueDeclaration; + + // Inherit information about parent type. + if (firstValueDeclaration.symbol.parent) { + result.parent = firstValueDeclaration.symbol.parent; + } + } + + result.declarations = declarations; + result.links.nameType = nameType; + if (propTypes.length > 2) { + // When `propTypes` has the potential to explode in size when normalized, defer normalization until absolutely needed + result.links.checkFlags |= CheckFlags.DeferredType; + result.links.deferralParent = containingType; + result.links.deferralConstituents = propTypes; + result.links.deferralWriteConstituents = writeTypes; + } + else { + result.links.type = isUnion ? getUnionType(propTypes) : getIntersectionType(propTypes); + if (writeTypes) { + result.links.writeType = isUnion ? getUnionType(writeTypes) : getIntersectionType(writeTypes); + } + } + return result; + } + + // Return the symbol for a given property in a union or intersection type, or undefined if the property + // does not exist in any constituent type. Note that the returned property may only be present in some + // constituents, in which case the isPartial flag is set when the containing type is union type. We need + // these partial properties when identifying discriminant properties, but otherwise they are filtered out + // and do not appear to be present in the union type. + function getUnionOrIntersectionProperty(type: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { + let property = skipObjectFunctionPropertyAugment ? + type.propertyCacheWithoutObjectFunctionPropertyAugment?.get(name) : + type.propertyCache?.get(name); + if (!property) { + property = createUnionOrIntersectionProperty(type, name, skipObjectFunctionPropertyAugment); + if (property) { + const properties = skipObjectFunctionPropertyAugment ? + type.propertyCacheWithoutObjectFunctionPropertyAugment ||= createSymbolTable() : + type.propertyCache ||= createSymbolTable(); + properties.set(name, property); + // Propagate an entry from the non-augmented cache to the augmented cache unless the property is partial. + if (skipObjectFunctionPropertyAugment && !(getCheckFlags(property) & CheckFlags.Partial) && !type.propertyCache?.get(name)) { + const properties = type.propertyCache ||= createSymbolTable(); + properties.set(name, property); + } + } + } + return property; + } + + function getCommonDeclarationsOfSymbols(symbols: Iterable) { + let commonDeclarations: Set | undefined; + for (const symbol of symbols) { + if (!symbol.declarations) { + return undefined; + } + if (!commonDeclarations) { + commonDeclarations = new Set(symbol.declarations); + continue; + } + commonDeclarations.forEach(declaration => { + if (!contains(symbol.declarations, declaration)) { + commonDeclarations!.delete(declaration); + } + }); + if (commonDeclarations.size === 0) { + return undefined; + } + } + return commonDeclarations; + } + + function getPropertyOfUnionOrIntersectionType(type: UnionOrIntersectionType, name: __String, skipObjectFunctionPropertyAugment?: boolean): Symbol | undefined { + const property = getUnionOrIntersectionProperty(type, name, skipObjectFunctionPropertyAugment); + // We need to filter out partial properties in union types + return property && !(getCheckFlags(property) & CheckFlags.ReadPartial) ? property : undefined; + } + + /** + * Return the reduced form of the given type. For a union type, it is a union of the normalized constituent types. + * For an intersection of types containing one or more mututally exclusive discriminant properties, it is 'never'. + * For all other types, it is simply the type itself. Discriminant properties are considered mutually exclusive when + * no constituent property has type 'never', but the intersection of the constituent property types is 'never'. + */ + function getReducedType(type: Type): Type { + if (type.flags & TypeFlags.Union && (type as UnionType).objectFlags & ObjectFlags.ContainsIntersections) { + return (type as UnionType).resolvedReducedType || ((type as UnionType).resolvedReducedType = getReducedUnionType(type as UnionType)); + } + else if (type.flags & TypeFlags.Intersection) { + if (!((type as IntersectionType).objectFlags & ObjectFlags.IsNeverIntersectionComputed)) { + (type as IntersectionType).objectFlags |= ObjectFlags.IsNeverIntersectionComputed | + (some(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isNeverReducedProperty) ? ObjectFlags.IsNeverIntersection : 0); + } + return (type as IntersectionType).objectFlags & ObjectFlags.IsNeverIntersection ? neverType : type; + } + return type; + } + + function getReducedUnionType(unionType: UnionType) { + const reducedTypes = sameMap(unionType.types, getReducedType); + if (reducedTypes === unionType.types) { + return unionType; + } + const reduced = getUnionType(reducedTypes); + if (reduced.flags & TypeFlags.Union) { + (reduced as UnionType).resolvedReducedType = reduced; + } + return reduced; + } + + function isNeverReducedProperty(prop: Symbol) { + return isDiscriminantWithNeverType(prop) || isConflictingPrivateProperty(prop); + } + + function isDiscriminantWithNeverType(prop: Symbol) { + // Return true for a synthetic non-optional property with non-uniform types, where at least one is + // a literal type and none is never, that reduces to never. + return !(prop.flags & SymbolFlags.Optional) && + (getCheckFlags(prop) & (CheckFlags.Discriminant | CheckFlags.HasNeverType)) === CheckFlags.Discriminant && + !!(getTypeOfSymbol(prop).flags & TypeFlags.Never); + } + + function isConflictingPrivateProperty(prop: Symbol) { + // Return true for a synthetic property with multiple declarations, at least one of which is private. + return !prop.valueDeclaration && !!(getCheckFlags(prop) & CheckFlags.ContainsPrivate); + } + + /** + * A union type which is reducible upon instantiation (meaning some members are removed under certain instantiations) + * must be kept generic, as that instantiation information needs to flow through the type system. By replacing all + * type parameters in the union with a special never type that is treated as a literal in `getReducedType`, we can cause + * the `getReducedType` logic to reduce the resulting type if possible (since only intersections with conflicting + * literal-typed properties are reducible). + */ + function isGenericReducibleType(type: Type): boolean { + return !!(type.flags & TypeFlags.Union && (type as UnionType).objectFlags & ObjectFlags.ContainsIntersections && some((type as UnionType).types, isGenericReducibleType) || + type.flags & TypeFlags.Intersection && isReducibleIntersection(type as IntersectionType)); + } + + function isReducibleIntersection(type: IntersectionType) { + const uniqueFilled = type.uniqueLiteralFilledInstantiation || (type.uniqueLiteralFilledInstantiation = instantiateType(type, uniqueLiteralMapper)); + return getReducedType(uniqueFilled) !== uniqueFilled; + } + + function elaborateNeverIntersection(errorInfo: DiagnosticMessageChain | undefined, type: Type) { + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsNeverIntersection) { + const neverProp = find(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isDiscriminantWithNeverType); + if (neverProp) { + return chainDiagnosticMessages(errorInfo, Diagnostics.The_intersection_0_was_reduced_to_never_because_property_1_has_conflicting_types_in_some_constituents, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.NoTypeReduction), symbolToString(neverProp)); + } + const privateProp = find(getPropertiesOfUnionOrIntersectionType(type as IntersectionType), isConflictingPrivateProperty); + if (privateProp) { + return chainDiagnosticMessages(errorInfo, Diagnostics.The_intersection_0_was_reduced_to_never_because_property_1_exists_in_multiple_constituents_and_is_private_in_some, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.NoTypeReduction), symbolToString(privateProp)); + } + } + return errorInfo; + } + + /** + * Return the symbol for the property with the given name in the given type. Creates synthetic union properties when + * necessary, maps primitive types and type parameters are to their apparent types, and augments with properties from + * Object and Function as appropriate. + * + * @param type a type to look up property from + * @param name a name of property to look up in a given type + */ + function getPropertyOfType(type: Type, name: __String, skipObjectFunctionPropertyAugment?: boolean, includeTypeOnlyMembers?: boolean): Symbol | undefined { + type = getReducedApparentType(type); + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + const symbol = resolved.members.get(name); + if (symbol && !includeTypeOnlyMembers && type.symbol?.flags & SymbolFlags.ValueModule && getSymbolLinks(type.symbol).typeOnlyExportStarMap?.has(name)) { + // If this is the type of a module, `resolved.members.get(name)` might have effectively skipped over + // an `export type * from './foo'`, leaving `symbolIsValue` unable to see that the symbol is being + // viewed through a type-only export. + return undefined; + } + if (symbol && symbolIsValue(symbol, includeTypeOnlyMembers)) { + return symbol; + } + if (skipObjectFunctionPropertyAugment) return undefined; + const functionType = resolved === anyFunctionType ? globalFunctionType : + resolved.callSignatures.length ? globalCallableFunctionType : + resolved.constructSignatures.length ? globalNewableFunctionType : + undefined; + if (functionType) { + const symbol = getPropertyOfObjectType(functionType, name); + if (symbol) { + return symbol; + } + } + return getPropertyOfObjectType(globalObjectType, name); + } + if (type.flags & TypeFlags.Intersection) { + const prop = getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, /*skipObjectFunctionPropertyAugment*/ true); + if (prop) { + return prop; + } + if (!skipObjectFunctionPropertyAugment) { + return getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, skipObjectFunctionPropertyAugment); + } + return undefined; + } + if (type.flags & TypeFlags.Union) { + return getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name, skipObjectFunctionPropertyAugment); + } + return undefined; + } + + function getSignaturesOfStructuredType(type: Type, kind: SignatureKind): readonly Signature[] { + if (type.flags & TypeFlags.StructuredType) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + return kind === SignatureKind.Call ? resolved.callSignatures : resolved.constructSignatures; + } + return emptyArray; + } + + /** + * Return the signatures of the given kind in the given type. Creates synthetic union signatures when necessary and + * maps primitive types and type parameters are to their apparent types. + */ + function getSignaturesOfType(type: Type, kind: SignatureKind): readonly Signature[] { + const result = getSignaturesOfStructuredType(getReducedApparentType(type), kind); + if (kind === SignatureKind.Call && !length(result) && type.flags & TypeFlags.Union) { + if ((type as UnionType).arrayFallbackSignatures) { + return (type as UnionType).arrayFallbackSignatures!; + } + // If the union is all different instantiations of a member of the global array type... + let memberName: __String; + if (everyType(type, t => !!t.symbol?.parent && isArrayOrTupleSymbol(t.symbol.parent) && (!memberName ? (memberName = t.symbol.escapedName, true) : memberName === t.symbol.escapedName))) { + // Transform the type from `(A[] | B[])["member"]` to `(A | B)[]["member"]` (since we pretend array is covariant anyway) + const arrayArg = mapType(type, t => getMappedType((isReadonlyArraySymbol(t.symbol.parent) ? globalReadonlyArrayType : globalArrayType).typeParameters![0], (t as AnonymousType).mapper!)); + const arrayType = createArrayType(arrayArg, someType(type, t => isReadonlyArraySymbol(t.symbol.parent))); + return (type as UnionType).arrayFallbackSignatures = getSignaturesOfType(getTypeOfPropertyOfType(arrayType, memberName!)!, kind); + } + (type as UnionType).arrayFallbackSignatures = result; + } + return result; + } + + function isArrayOrTupleSymbol(symbol: Symbol | undefined) { + if (!symbol || !globalArrayType.symbol || !globalReadonlyArrayType.symbol) { + return false; + } + return !!getSymbolIfSameReference(symbol, globalArrayType.symbol) || !!getSymbolIfSameReference(symbol, globalReadonlyArrayType.symbol); + } + + function isReadonlyArraySymbol(symbol: Symbol | undefined) { + if (!symbol || !globalReadonlyArrayType.symbol) { + return false; + } + return !!getSymbolIfSameReference(symbol, globalReadonlyArrayType.symbol); + } + + function findIndexInfo(indexInfos: readonly IndexInfo[], keyType: Type) { + return find(indexInfos, info => info.keyType === keyType); + } + + function findApplicableIndexInfo(indexInfos: readonly IndexInfo[], keyType: Type) { + // Index signatures for type 'string' are considered only when no other index signatures apply. + let stringIndexInfo: IndexInfo | undefined; + let applicableInfo: IndexInfo | undefined; + let applicableInfos: IndexInfo[] | undefined; + for (const info of indexInfos) { + if (info.keyType === stringType) { + stringIndexInfo = info; + } + else if (isApplicableIndexType(keyType, info.keyType)) { + if (!applicableInfo) { + applicableInfo = info; + } + else { + (applicableInfos || (applicableInfos = [applicableInfo])).push(info); + } + } + } + // When more than one index signature is applicable we create a synthetic IndexInfo. Instead of computing + // the intersected key type, we just use unknownType for the key type as nothing actually depends on the + // keyType property of the returned IndexInfo. + return applicableInfos ? createIndexInfo(unknownType, getIntersectionType(map(applicableInfos, info => info.type)), reduceLeft(applicableInfos, (isReadonly, info) => isReadonly && info.isReadonly, /*initial*/ true)) : + applicableInfo ? applicableInfo : + stringIndexInfo && isApplicableIndexType(keyType, stringType) ? stringIndexInfo : + undefined; + } + + function isApplicableIndexType(source: Type, target: Type): boolean { + // A 'string' index signature applies to types assignable to 'string' or 'number', and a 'number' index + // signature applies to types assignable to 'number', `${number}` and numeric string literal types. + return isTypeAssignableTo(source, target) || + target === stringType && isTypeAssignableTo(source, numberType) || + target === numberType && (source === numericStringType || !!(source.flags & TypeFlags.StringLiteral) && isNumericLiteralName((source as StringLiteralType).value)); + } + + function getIndexInfosOfStructuredType(type: Type): readonly IndexInfo[] { + if (type.flags & TypeFlags.StructuredType) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + return resolved.indexInfos; + } + return emptyArray; + } + + function getIndexInfosOfType(type: Type): readonly IndexInfo[] { + return getIndexInfosOfStructuredType(getReducedApparentType(type)); + } + + // Return the indexing info of the given kind in the given type. Creates synthetic union index types when necessary and + // maps primitive types and type parameters are to their apparent types. + function getIndexInfoOfType(type: Type, keyType: Type): IndexInfo | undefined { + return findIndexInfo(getIndexInfosOfType(type), keyType); + } + + // Return the index type of the given kind in the given type. Creates synthetic union index types when necessary and + // maps primitive types and type parameters are to their apparent types. + function getIndexTypeOfType(type: Type, keyType: Type): Type | undefined { + return getIndexInfoOfType(type, keyType)?.type; + } + + function getApplicableIndexInfos(type: Type, keyType: Type): IndexInfo[] { + return getIndexInfosOfType(type).filter(info => isApplicableIndexType(keyType, info.keyType)); + } + + function getApplicableIndexInfo(type: Type, keyType: Type): IndexInfo | undefined { + return findApplicableIndexInfo(getIndexInfosOfType(type), keyType); + } + + function getApplicableIndexInfoForName(type: Type, name: __String): IndexInfo | undefined { + return getApplicableIndexInfo(type, isLateBoundName(name) ? esSymbolType : getStringLiteralType(unescapeLeadingUnderscores(name))); + } + + // Return list of type parameters with duplicates removed (duplicate identifier errors are generated in the actual + // type checking functions). + function getTypeParametersFromDeclaration(declaration: DeclarationWithTypeParameters): readonly TypeParameter[] | undefined { + let result: TypeParameter[] | undefined; + for (const node of getEffectiveTypeParameterDeclarations(declaration)) { + result = appendIfUnique(result, getDeclaredTypeOfTypeParameter(node.symbol)); + } + return result?.length ? result + : isFunctionDeclaration(declaration) ? getSignatureOfTypeTag(declaration)?.typeParameters + : undefined; + } + + function symbolsToArray(symbols: SymbolTable): Symbol[] { + const result: Symbol[] = []; + symbols.forEach((symbol, id) => { + if (!isReservedMemberName(id)) { + result.push(symbol); + } + }); + return result; + } + + function tryFindAmbientModule(moduleName: string, withAugmentations: boolean) { + if (isExternalModuleNameRelative(moduleName)) { + return undefined; + } + const symbol = getSymbol(globals, '"' + moduleName + '"' as __String, SymbolFlags.ValueModule); + // merged symbol is module declaration symbol combined with all augmentations + return symbol && withAugmentations ? getMergedSymbol(symbol) : symbol; + } + + function hasEffectiveQuestionToken(node: ParameterDeclaration | JSDocParameterTag | JSDocPropertyTag) { + return hasQuestionToken(node) || isOptionalJSDocPropertyLikeTag(node) || isParameter(node) && isJSDocOptionalParameter(node); + } + + function isOptionalParameter(node: ParameterDeclaration | JSDocParameterTag | JSDocPropertyTag) { + if (hasEffectiveQuestionToken(node)) { + return true; + } + if (!isParameter(node)) { + return false; + } + if (node.initializer) { + const signature = getSignatureFromDeclaration(node.parent); + const parameterIndex = node.parent.parameters.indexOf(node); + Debug.assert(parameterIndex >= 0); + // Only consider syntactic or instantiated parameters as optional, not `void` parameters as this function is used + // in grammar checks and checking for `void` too early results in parameter types widening too early + // and causes some noImplicitAny errors to be lost. + return parameterIndex >= getMinArgumentCount(signature, MinArgumentCountFlags.StrongArityForUntypedJS | MinArgumentCountFlags.VoidIsNonOptional); + } + const iife = getImmediatelyInvokedFunctionExpression(node.parent); + if (iife) { + return !node.type && + !node.dotDotDotToken && + node.parent.parameters.indexOf(node) >= getEffectiveCallArguments(iife).length; + } + + return false; + } + + function isOptionalPropertyDeclaration(node: Declaration) { + return isPropertyDeclaration(node) && !hasAccessorModifier(node) && node.questionToken; + } + + function createTypePredicate(kind: TypePredicateKind, parameterName: string | undefined, parameterIndex: number | undefined, type: Type | undefined): TypePredicate { + return { kind, parameterName, parameterIndex, type } as TypePredicate; + } + + /** + * Gets the minimum number of type arguments needed to satisfy all non-optional type + * parameters. + */ + function getMinTypeArgumentCount(typeParameters: readonly TypeParameter[] | undefined): number { + let minTypeArgumentCount = 0; + if (typeParameters) { + for (let i = 0; i < typeParameters.length; i++) { + if (!hasTypeParameterDefault(typeParameters[i])) { + minTypeArgumentCount = i + 1; + } + } + } + return minTypeArgumentCount; + } + + /** + * Fill in default types for unsupplied type arguments. If `typeArguments` is undefined + * when a default type is supplied, a new array will be created and returned. + * + * @param typeArguments The supplied type arguments. + * @param typeParameters The requested type parameters. + * @param minTypeArgumentCount The minimum number of required type arguments. + */ + function fillMissingTypeArguments(typeArguments: readonly Type[], typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean): Type[]; + function fillMissingTypeArguments(typeArguments: readonly Type[] | undefined, typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean): Type[] | undefined; + function fillMissingTypeArguments(typeArguments: readonly Type[] | undefined, typeParameters: readonly TypeParameter[] | undefined, minTypeArgumentCount: number, isJavaScriptImplicitAny: boolean) { + const numTypeParameters = length(typeParameters); + if (!numTypeParameters) { + return []; + } + const numTypeArguments = length(typeArguments); + if (isJavaScriptImplicitAny || (numTypeArguments >= minTypeArgumentCount && numTypeArguments <= numTypeParameters)) { + const result = typeArguments ? typeArguments.slice() : []; + // Map invalid forward references in default types to the error type + for (let i = numTypeArguments; i < numTypeParameters; i++) { + result[i] = errorType; + } + const baseDefaultType = getDefaultTypeArgumentType(isJavaScriptImplicitAny); + for (let i = numTypeArguments; i < numTypeParameters; i++) { + let defaultType = getDefaultFromTypeParameter(typeParameters![i]); + if (isJavaScriptImplicitAny && defaultType && (isTypeIdenticalTo(defaultType, unknownType) || isTypeIdenticalTo(defaultType, emptyObjectType))) { + defaultType = anyType; + } + result[i] = defaultType ? instantiateType(defaultType, createTypeMapper(typeParameters!, result)) : baseDefaultType; + } + result.length = typeParameters!.length; + return result; + } + return typeArguments && typeArguments.slice(); + } + + function getSignatureFromDeclaration(declaration: SignatureDeclaration | JSDocSignature): Signature { + const links = getNodeLinks(declaration); + if (!links.resolvedSignature) { + const parameters: Symbol[] = []; + let flags = SignatureFlags.None; + let minArgumentCount = 0; + let thisParameter: Symbol | undefined; + let thisTag: JSDocThisTag | undefined = isInJSFile(declaration) ? getJSDocThisTag(declaration) : undefined; + let hasThisParameter = false; + const iife = getImmediatelyInvokedFunctionExpression(declaration); + const isJSConstructSignature = isJSDocConstructSignature(declaration); + const isUntypedSignatureInJSFile = !iife && + isInJSFile(declaration) && + isValueSignatureDeclaration(declaration) && + !hasJSDocParameterTags(declaration) && + !getJSDocType(declaration); + if (isUntypedSignatureInJSFile) { + flags |= SignatureFlags.IsUntypedSignatureInJSFile; + } + + // If this is a JSDoc construct signature, then skip the first parameter in the + // parameter list. The first parameter represents the return type of the construct + // signature. + for (let i = isJSConstructSignature ? 1 : 0; i < declaration.parameters.length; i++) { + const param = declaration.parameters[i]; + if (isInJSFile(param) && isJSDocThisTag(param)) { + thisTag = param; + continue; + } + + let paramSymbol = param.symbol; + const type = isJSDocParameterTag(param) ? (param.typeExpression && param.typeExpression.type) : param.type; + // Include parameter symbol instead of property symbol in the signature + if (paramSymbol && !!(paramSymbol.flags & SymbolFlags.Property) && !isBindingPattern(param.name)) { + const resolvedSymbol = resolveName(param, paramSymbol.escapedName, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + paramSymbol = resolvedSymbol!; + } + if (i === 0 && paramSymbol.escapedName === InternalSymbolName.This) { + hasThisParameter = true; + thisParameter = param.symbol; + } + else { + parameters.push(paramSymbol); + } + + if (type && type.kind === SyntaxKind.LiteralType) { + flags |= SignatureFlags.HasLiteralTypes; + } + + // Record a new minimum argument count if this is not an optional parameter + const isOptionalParameter = hasEffectiveQuestionToken(param) || + isParameter(param) && param.initializer || isRestParameter(param) || + iife && parameters.length > iife.arguments.length && !type; + if (!isOptionalParameter) { + minArgumentCount = parameters.length; + } + } + + // If only one accessor includes a this-type annotation, the other behaves as if it had the same type annotation + if ( + (declaration.kind === SyntaxKind.GetAccessor || declaration.kind === SyntaxKind.SetAccessor) && + hasBindableName(declaration) && + (!hasThisParameter || !thisParameter) + ) { + const otherKind = declaration.kind === SyntaxKind.GetAccessor ? SyntaxKind.SetAccessor : SyntaxKind.GetAccessor; + const other = getDeclarationOfKind(getSymbolOfDeclaration(declaration), otherKind); + if (other) { + thisParameter = getAnnotatedAccessorThisParameter(other); + } + } + + if (thisTag && thisTag.typeExpression) { + thisParameter = createSymbolWithType(createSymbol(SymbolFlags.FunctionScopedVariable, InternalSymbolName.This), getTypeFromTypeNode(thisTag.typeExpression)); + } + + const hostDeclaration = isJSDocSignature(declaration) ? getEffectiveJSDocHost(declaration) : declaration; + const classType = hostDeclaration && isConstructorDeclaration(hostDeclaration) ? + getDeclaredTypeOfClassOrInterface(getMergedSymbol((hostDeclaration.parent as ClassDeclaration).symbol)) + : undefined; + const typeParameters = classType ? classType.localTypeParameters : getTypeParametersFromDeclaration(declaration); + if (hasRestParameter(declaration) || isInJSFile(declaration) && maybeAddJsSyntheticRestParameter(declaration, parameters)) { + flags |= SignatureFlags.HasRestParameter; + } + if ( + isConstructorTypeNode(declaration) && hasSyntacticModifier(declaration, ModifierFlags.Abstract) || + isConstructorDeclaration(declaration) && hasSyntacticModifier(declaration.parent, ModifierFlags.Abstract) + ) { + flags |= SignatureFlags.Abstract; + } + links.resolvedSignature = createSignature(declaration, typeParameters, thisParameter, parameters, /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, minArgumentCount, flags); + } + return links.resolvedSignature; + } + + /** + * A JS function gets a synthetic rest parameter if it references `arguments` AND: + * 1. It has no parameters but at least one `@param` with a type that starts with `...` + * OR + * 2. It has at least one parameter, and the last parameter has a matching `@param` with a type that starts with `...` + */ + function maybeAddJsSyntheticRestParameter(declaration: SignatureDeclaration | JSDocSignature, parameters: Symbol[]): boolean { + if (isJSDocSignature(declaration) || !containsArgumentsReference(declaration)) { + return false; + } + const lastParam = lastOrUndefined(declaration.parameters); + const lastParamTags = lastParam ? getJSDocParameterTags(lastParam) : getJSDocTags(declaration).filter(isJSDocParameterTag); + const lastParamVariadicType = firstDefined(lastParamTags, p => p.typeExpression && isJSDocVariadicType(p.typeExpression.type) ? p.typeExpression.type : undefined); + + const syntheticArgsSymbol = createSymbol(SymbolFlags.Variable, "args" as __String, CheckFlags.RestParameter); + if (lastParamVariadicType) { + // Parameter has effective annotation, lock in type + syntheticArgsSymbol.links.type = createArrayType(getTypeFromTypeNode(lastParamVariadicType.type)); + } + else { + // Parameter has no annotation + // By using a `DeferredType` symbol, we allow the type of this rest arg to be overriden by contextual type assignment so long as its type hasn't been + // cached by `getTypeOfSymbol` yet. + syntheticArgsSymbol.links.checkFlags |= CheckFlags.DeferredType; + syntheticArgsSymbol.links.deferralParent = neverType; + syntheticArgsSymbol.links.deferralConstituents = [anyArrayType]; + syntheticArgsSymbol.links.deferralWriteConstituents = [anyArrayType]; + } + if (lastParamVariadicType) { + // Replace the last parameter with a rest parameter. + parameters.pop(); + } + parameters.push(syntheticArgsSymbol); + return true; + } + + function getSignatureOfTypeTag(node: SignatureDeclaration | JSDocSignature) { + // should be attached to a function declaration or expression + if (!(isInJSFile(node) && isFunctionLikeDeclaration(node))) return undefined; + const typeTag = getJSDocTypeTag(node); + return typeTag?.typeExpression && getSingleCallSignature(getTypeFromTypeNode(typeTag.typeExpression)); + } + + function getParameterTypeOfTypeTag(func: FunctionLikeDeclaration, parameter: ParameterDeclaration) { + const signature = getSignatureOfTypeTag(func); + if (!signature) return undefined; + const pos = func.parameters.indexOf(parameter); + return parameter.dotDotDotToken ? getRestTypeAtPosition(signature, pos) : getTypeAtPosition(signature, pos); + } + + function getReturnTypeOfTypeTag(node: SignatureDeclaration | JSDocSignature) { + const signature = getSignatureOfTypeTag(node); + return signature && getReturnTypeOfSignature(signature); + } + + function containsArgumentsReference(declaration: SignatureDeclaration): boolean { + const links = getNodeLinks(declaration); + if (links.containsArgumentsReference === undefined) { + if (links.flags & NodeCheckFlags.CaptureArguments) { + links.containsArgumentsReference = true; + } + else { + links.containsArgumentsReference = traverse((declaration as FunctionLikeDeclaration).body!); + } + } + return links.containsArgumentsReference; + + function traverse(node: Node): boolean { + if (!node) return false; + switch (node.kind) { + case SyntaxKind.Identifier: + return (node as Identifier).escapedText === argumentsSymbol.escapedName && getReferencedValueSymbol(node as Identifier) === argumentsSymbol; + + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return (node as NamedDeclaration).name!.kind === SyntaxKind.ComputedPropertyName + && traverse((node as NamedDeclaration).name!); + + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + return traverse((node as PropertyAccessExpression | ElementAccessExpression).expression); + + case SyntaxKind.PropertyAssignment: + return traverse((node as PropertyAssignment).initializer); + + default: + return !nodeStartsNewLexicalEnvironment(node) && !isPartOfTypeNode(node) && !!forEachChild(node, traverse); + } + } + } + + function getSignaturesOfSymbol(symbol: Symbol | undefined): Signature[] { + if (!symbol || !symbol.declarations) return emptyArray; + const result: Signature[] = []; + for (let i = 0; i < symbol.declarations.length; i++) { + const decl = symbol.declarations[i]; + if (!isFunctionLike(decl)) continue; + // Don't include signature if node is the implementation of an overloaded function. A node is considered + // an implementation node if it has a body and the previous node is of the same kind and immediately + // precedes the implementation node (i.e. has the same parent and ends where the implementation starts). + if (i > 0 && (decl as FunctionLikeDeclaration).body) { + const previous = symbol.declarations[i - 1]; + if (decl.parent === previous.parent && decl.kind === previous.kind && decl.pos === previous.end) { + continue; + } + } + if (isInJSFile(decl) && decl.jsDoc) { + const tags = getJSDocOverloadTags(decl); + if (length(tags)) { + for (const tag of tags) { + const jsDocSignature = tag.typeExpression; + if (jsDocSignature.type === undefined && !isConstructorDeclaration(decl)) { + reportImplicitAny(jsDocSignature, anyType); + } + result.push(getSignatureFromDeclaration(jsDocSignature)); + } + continue; + } + } + // If this is a function or method declaration, get the signature from the @type tag for the sake of optional parameters. + // Exclude contextually-typed kinds because we already apply the @type tag to the context, plus applying it here to the initializer would supress checks that the two are compatible. + result.push( + (!isFunctionExpressionOrArrowFunction(decl) && + !isObjectLiteralMethod(decl) && + getSignatureOfTypeTag(decl)) || + getSignatureFromDeclaration(decl), + ); + } + return result; + } + + function resolveExternalModuleTypeByLiteral(name: StringLiteral) { + const moduleSym = resolveExternalModuleName(name, name); + if (moduleSym) { + const resolvedModuleSymbol = resolveExternalModuleSymbol(moduleSym); + if (resolvedModuleSymbol) { + return getTypeOfSymbol(resolvedModuleSymbol); + } + } + + return anyType; + } + + function getThisTypeOfSignature(signature: Signature): Type | undefined { + if (signature.thisParameter) { + return getTypeOfSymbol(signature.thisParameter); + } + } + + function getTypePredicateOfSignature(signature: Signature): TypePredicate | undefined { + if (!signature.resolvedTypePredicate) { + if (signature.target) { + const targetTypePredicate = getTypePredicateOfSignature(signature.target); + signature.resolvedTypePredicate = targetTypePredicate ? instantiateTypePredicate(targetTypePredicate, signature.mapper!) : noTypePredicate; + } + else if (signature.compositeSignatures) { + signature.resolvedTypePredicate = getUnionOrIntersectionTypePredicate(signature.compositeSignatures, signature.compositeKind) || noTypePredicate; + } + else { + const type = signature.declaration && getEffectiveReturnTypeNode(signature.declaration); + let jsdocPredicate: TypePredicate | undefined; + if (!type) { + const jsdocSignature = getSignatureOfTypeTag(signature.declaration!); + if (jsdocSignature && signature !== jsdocSignature) { + jsdocPredicate = getTypePredicateOfSignature(jsdocSignature); + } + } + if (type || jsdocPredicate) { + signature.resolvedTypePredicate = type && isTypePredicateNode(type) ? + createTypePredicateFromTypePredicateNode(type, signature) : + jsdocPredicate || noTypePredicate; + } + else if (signature.declaration && isFunctionLikeDeclaration(signature.declaration) && (!signature.resolvedReturnType || signature.resolvedReturnType.flags & TypeFlags.Boolean) && getParameterCount(signature) > 0) { + const { declaration } = signature; + signature.resolvedTypePredicate = noTypePredicate; // avoid infinite loop + signature.resolvedTypePredicate = getTypePredicateFromBody(declaration) || noTypePredicate; + } + else { + signature.resolvedTypePredicate = noTypePredicate; + } + } + Debug.assert(!!signature.resolvedTypePredicate); + } + return signature.resolvedTypePredicate === noTypePredicate ? undefined : signature.resolvedTypePredicate; + } + + function createTypePredicateFromTypePredicateNode(node: TypePredicateNode, signature: Signature): TypePredicate { + const parameterName = node.parameterName; + const type = node.type && getTypeFromTypeNode(node.type); + return parameterName.kind === SyntaxKind.ThisType ? + createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsThis : TypePredicateKind.This, /*parameterName*/ undefined, /*parameterIndex*/ undefined, type) : + createTypePredicate(node.assertsModifier ? TypePredicateKind.AssertsIdentifier : TypePredicateKind.Identifier, parameterName.escapedText as string, findIndex(signature.parameters, p => p.escapedName === parameterName.escapedText), type); + } + + function getUnionOrIntersectionType(types: Type[], kind: TypeFlags | undefined, unionReduction?: UnionReduction) { + return kind !== TypeFlags.Intersection ? getUnionType(types, unionReduction) : getIntersectionType(types); + } + + function getReturnTypeOfSignature(signature: Signature): Type { + if (!signature.resolvedReturnType) { + if (!pushTypeResolution(signature, TypeSystemPropertyName.ResolvedReturnType)) { + return errorType; + } + let type = signature.target ? instantiateType(getReturnTypeOfSignature(signature.target), signature.mapper) : + signature.compositeSignatures ? instantiateType(getUnionOrIntersectionType(map(signature.compositeSignatures, getReturnTypeOfSignature), signature.compositeKind, UnionReduction.Subtype), signature.mapper) : + getReturnTypeFromAnnotation(signature.declaration!) || + (nodeIsMissing((signature.declaration as FunctionLikeDeclaration).body) ? anyType : getReturnTypeFromBody(signature.declaration as FunctionLikeDeclaration)); + if (signature.flags & SignatureFlags.IsInnerCallChain) { + type = addOptionalTypeMarker(type); + } + else if (signature.flags & SignatureFlags.IsOuterCallChain) { + type = getOptionalType(type); + } + if (!popTypeResolution()) { + if (signature.declaration) { + const typeNode = getEffectiveReturnTypeNode(signature.declaration); + if (typeNode) { + error(typeNode, Diagnostics.Return_type_annotation_circularly_references_itself); + } + else if (noImplicitAny) { + const declaration = signature.declaration as Declaration; + const name = getNameOfDeclaration(declaration); + if (name) { + error(name, Diagnostics._0_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions, declarationNameToString(name)); + } + else { + error(declaration, Diagnostics.Function_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions); + } + } + } + type = anyType; + } + signature.resolvedReturnType ??= type; + } + return signature.resolvedReturnType; + } + + function getReturnTypeFromAnnotation(declaration: SignatureDeclaration | JSDocSignature) { + if (declaration.kind === SyntaxKind.Constructor) { + return getDeclaredTypeOfClassOrInterface(getMergedSymbol((declaration.parent as ClassDeclaration).symbol)); + } + const typeNode = getEffectiveReturnTypeNode(declaration); + if (isJSDocSignature(declaration)) { + const root = getJSDocRoot(declaration); + if (root && isConstructorDeclaration(root.parent) && !typeNode) { + return getDeclaredTypeOfClassOrInterface(getMergedSymbol((root.parent.parent as ClassDeclaration).symbol)); + } + } + if (isJSDocConstructSignature(declaration)) { + return getTypeFromTypeNode((declaration.parameters[0] as ParameterDeclaration).type!); // TODO: GH#18217 + } + if (typeNode) { + return getTypeFromTypeNode(typeNode); + } + if (declaration.kind === SyntaxKind.GetAccessor && hasBindableName(declaration)) { + const jsDocType = isInJSFile(declaration) && getTypeForDeclarationFromJSDocComment(declaration); + if (jsDocType) { + return jsDocType; + } + const setter = getDeclarationOfKind(getSymbolOfDeclaration(declaration), SyntaxKind.SetAccessor); + const setterType = getAnnotatedAccessorType(setter); + if (setterType) { + return setterType; + } + } + return getReturnTypeOfTypeTag(declaration); + } + + function isResolvingReturnTypeOfSignature(signature: Signature): boolean { + return signature.compositeSignatures && some(signature.compositeSignatures, isResolvingReturnTypeOfSignature) || + !signature.resolvedReturnType && findResolutionCycleStartIndex(signature, TypeSystemPropertyName.ResolvedReturnType) >= 0; + } + + function getRestTypeOfSignature(signature: Signature): Type { + return tryGetRestTypeOfSignature(signature) || anyType; + } + + function tryGetRestTypeOfSignature(signature: Signature): Type | undefined { + if (signatureHasRestParameter(signature)) { + const sigRestType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + const restType = isTupleType(sigRestType) ? getRestTypeOfTupleType(sigRestType) : sigRestType; + return restType && getIndexTypeOfType(restType, numberType); + } + return undefined; + } + + function getSignatureInstantiation(signature: Signature, typeArguments: readonly Type[] | undefined, isJavascript: boolean, inferredTypeParameters?: readonly TypeParameter[]): Signature { + const instantiatedSignature = getSignatureInstantiationWithoutFillingInTypeArguments(signature, fillMissingTypeArguments(typeArguments, signature.typeParameters, getMinTypeArgumentCount(signature.typeParameters), isJavascript)); + if (inferredTypeParameters) { + const returnSignature = getSingleCallOrConstructSignature(getReturnTypeOfSignature(instantiatedSignature)); + if (returnSignature) { + const newReturnSignature = cloneSignature(returnSignature); + newReturnSignature.typeParameters = inferredTypeParameters; + const newInstantiatedSignature = cloneSignature(instantiatedSignature); + newInstantiatedSignature.resolvedReturnType = getOrCreateTypeFromSignature(newReturnSignature); + return newInstantiatedSignature; + } + } + return instantiatedSignature; + } + + function getSignatureInstantiationWithoutFillingInTypeArguments(signature: Signature, typeArguments: readonly Type[] | undefined): Signature { + const instantiations = signature.instantiations || (signature.instantiations = new Map()); + const id = getTypeListId(typeArguments); + let instantiation = instantiations.get(id); + if (!instantiation) { + instantiations.set(id, instantiation = createSignatureInstantiation(signature, typeArguments)); + } + return instantiation; + } + + function createSignatureInstantiation(signature: Signature, typeArguments: readonly Type[] | undefined): Signature { + return instantiateSignature(signature, createSignatureTypeMapper(signature, typeArguments), /*eraseTypeParameters*/ true); + } + + function createSignatureTypeMapper(signature: Signature, typeArguments: readonly Type[] | undefined): TypeMapper { + return createTypeMapper(signature.typeParameters!, typeArguments); + } + + function getErasedSignature(signature: Signature): Signature { + return signature.typeParameters ? + signature.erasedSignatureCache || (signature.erasedSignatureCache = createErasedSignature(signature)) : + signature; + } + + function createErasedSignature(signature: Signature) { + // Create an instantiation of the signature where all type arguments are the any type. + return instantiateSignature(signature, createTypeEraser(signature.typeParameters!), /*eraseTypeParameters*/ true); + } + + function getCanonicalSignature(signature: Signature): Signature { + return signature.typeParameters ? + signature.canonicalSignatureCache || (signature.canonicalSignatureCache = createCanonicalSignature(signature)) : + signature; + } + + function createCanonicalSignature(signature: Signature) { + // Create an instantiation of the signature where each unconstrained type parameter is replaced with + // its original. When a generic class or interface is instantiated, each generic method in the class or + // interface is instantiated with a fresh set of cloned type parameters (which we need to handle scenarios + // where different generations of the same type parameter are in scope). This leads to a lot of new type + // identities, and potentially a lot of work comparing those identities, so here we create an instantiation + // that uses the original type identities for all unconstrained type parameters. + return getSignatureInstantiation( + signature, + map(signature.typeParameters, tp => tp.target && !getConstraintOfTypeParameter(tp.target) ? tp.target : tp), + isInJSFile(signature.declaration), + ); + } + + function getImplementationSignature(signature: Signature) { + return signature.typeParameters ? + signature.implementationSignatureCache ||= createImplementationSignature(signature) : + signature; + } + + function createImplementationSignature(signature: Signature) { + return signature.typeParameters ? instantiateSignature(signature, createTypeMapper([], [])) : signature; + } + + function getBaseSignature(signature: Signature) { + const typeParameters = signature.typeParameters; + if (typeParameters) { + if (signature.baseSignatureCache) { + return signature.baseSignatureCache; + } + const typeEraser = createTypeEraser(typeParameters); + const baseConstraintMapper = createTypeMapper(typeParameters, map(typeParameters, tp => getConstraintOfTypeParameter(tp) || unknownType)); + let baseConstraints: readonly Type[] = map(typeParameters, tp => instantiateType(tp, baseConstraintMapper) || unknownType); + // Run N type params thru the immediate constraint mapper up to N times + // This way any noncircular interdependent type parameters are definitely resolved to their external dependencies + for (let i = 0; i < typeParameters.length - 1; i++) { + baseConstraints = instantiateTypes(baseConstraints, baseConstraintMapper); + } + // and then apply a type eraser to remove any remaining circularly dependent type parameters + baseConstraints = instantiateTypes(baseConstraints, typeEraser); + return signature.baseSignatureCache = instantiateSignature(signature, createTypeMapper(typeParameters, baseConstraints), /*eraseTypeParameters*/ true); + } + return signature; + } + + function getOrCreateTypeFromSignature(signature: Signature, outerTypeParameters?: TypeParameter[]): ObjectType { + // There are two ways to declare a construct signature, one is by declaring a class constructor + // using the constructor keyword, and the other is declaring a bare construct signature in an + // object type literal or interface (using the new keyword). Each way of declaring a constructor + // will result in a different declaration kind. + if (!signature.isolatedSignatureType) { + const kind = signature.declaration?.kind; + + // If declaration is undefined, it is likely to be the signature of the default constructor. + const isConstructor = kind === undefined || kind === SyntaxKind.Constructor || kind === SyntaxKind.ConstructSignature || kind === SyntaxKind.ConstructorType; + + // The type must have a symbol with a `Function` flag and a declaration in order to be correctly flagged as possibly containing + // type variables by `couldContainTypeVariables` + const type = createObjectType(ObjectFlags.Anonymous | ObjectFlags.SingleSignatureType, createSymbol(SymbolFlags.Function, InternalSymbolName.Function)) as SingleSignatureType; + if (signature.declaration && !nodeIsSynthesized(signature.declaration)) { // skip synthetic declarations - keeping those around could be bad, since they lack a parent pointer + type.symbol.declarations = [signature.declaration]; + type.symbol.valueDeclaration = signature.declaration; + } + outerTypeParameters ||= signature.declaration && getOuterTypeParameters(signature.declaration, /*includeThisTypes*/ true); + type.outerTypeParameters = outerTypeParameters; + + type.members = emptySymbols; + type.properties = emptyArray; + type.callSignatures = !isConstructor ? [signature] : emptyArray; + type.constructSignatures = isConstructor ? [signature] : emptyArray; + type.indexInfos = emptyArray; + signature.isolatedSignatureType = type; + } + + return signature.isolatedSignatureType; + } + + function getIndexSymbol(symbol: Symbol): Symbol | undefined { + return symbol.members ? getIndexSymbolFromSymbolTable(symbol.members) : undefined; + } + + function getIndexSymbolFromSymbolTable(symbolTable: SymbolTable): Symbol | undefined { + return symbolTable.get(InternalSymbolName.Index); + } + + function createIndexInfo(keyType: Type, type: Type, isReadonly: boolean, declaration?: IndexSignatureDeclaration): IndexInfo { + return { keyType, type, isReadonly, declaration }; + } + + function getIndexInfosOfSymbol(symbol: Symbol): IndexInfo[] { + const indexSymbol = getIndexSymbol(symbol); + return indexSymbol ? getIndexInfosOfIndexSymbol(indexSymbol) : emptyArray; + } + + function getIndexInfosOfIndexSymbol(indexSymbol: Symbol): IndexInfo[] { + if (indexSymbol.declarations) { + const indexInfos: IndexInfo[] = []; + for (const declaration of (indexSymbol.declarations as IndexSignatureDeclaration[])) { + if (declaration.parameters.length === 1) { + const parameter = declaration.parameters[0]; + if (parameter.type) { + forEachType(getTypeFromTypeNode(parameter.type), keyType => { + if (isValidIndexKeyType(keyType) && !findIndexInfo(indexInfos, keyType)) { + indexInfos.push(createIndexInfo(keyType, declaration.type ? getTypeFromTypeNode(declaration.type) : anyType, hasEffectiveModifier(declaration, ModifierFlags.Readonly), declaration)); + } + }); + } + } + } + return indexInfos; + } + return emptyArray; + } + + function isValidIndexKeyType(type: Type): boolean { + return !!(type.flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.ESSymbol)) || isPatternLiteralType(type) || + !!(type.flags & TypeFlags.Intersection) && !isGenericType(type) && some((type as IntersectionType).types, isValidIndexKeyType); + } + + function getConstraintDeclaration(type: TypeParameter): TypeNode | undefined { + return mapDefined(filter(type.symbol && type.symbol.declarations, isTypeParameterDeclaration), getEffectiveConstraintOfTypeParameter)[0]; + } + + function getInferredTypeParameterConstraint(typeParameter: TypeParameter, omitTypeReferences?: boolean) { + let inferences: Type[] | undefined; + if (typeParameter.symbol?.declarations) { + for (const declaration of typeParameter.symbol.declarations) { + if (declaration.parent.kind === SyntaxKind.InferType) { + // When an 'infer T' declaration is immediately contained in a type reference node + // (such as 'Foo'), T's constraint is inferred from the constraint of the + // corresponding type parameter in 'Foo'. When multiple 'infer T' declarations are + // present, we form an intersection of the inferred constraint types. + const [childTypeParameter = declaration.parent, grandParent] = walkUpParenthesizedTypesAndGetParentAndChild(declaration.parent.parent); + if (grandParent.kind === SyntaxKind.TypeReference && !omitTypeReferences) { + const typeReference = grandParent as TypeReferenceNode; + const typeParameters = getTypeParametersForTypeReferenceOrImport(typeReference); + if (typeParameters) { + const index = typeReference.typeArguments!.indexOf(childTypeParameter as TypeNode); + if (index < typeParameters.length) { + const declaredConstraint = getConstraintOfTypeParameter(typeParameters[index]); + if (declaredConstraint) { + // Type parameter constraints can reference other type parameters so + // constraints need to be instantiated. If instantiation produces the + // type parameter itself, we discard that inference. For example, in + // type Foo = [T, U]; + // type Bar = T extends Foo ? Foo : T; + // the instantiated constraint for U is X, so we discard that inference. + const mapper = makeDeferredTypeMapper( + typeParameters, + typeParameters.map((_, index) => () => { + return getEffectiveTypeArgumentAtIndex(typeReference, typeParameters, index); + }), + ); + const constraint = instantiateType(declaredConstraint, mapper); + if (constraint !== typeParameter) { + inferences = append(inferences, constraint); + } + } + } + } + } + // When an 'infer T' declaration is immediately contained in a rest parameter declaration, a rest type + // or a named rest tuple element, we infer an 'unknown[]' constraint. + else if ( + grandParent.kind === SyntaxKind.Parameter && (grandParent as ParameterDeclaration).dotDotDotToken || + grandParent.kind === SyntaxKind.RestType || + grandParent.kind === SyntaxKind.NamedTupleMember && (grandParent as NamedTupleMember).dotDotDotToken + ) { + inferences = append(inferences, createArrayType(unknownType)); + } + // When an 'infer T' declaration is immediately contained in a string template type, we infer a 'string' + // constraint. + else if (grandParent.kind === SyntaxKind.TemplateLiteralTypeSpan) { + inferences = append(inferences, stringType); + } + // When an 'infer T' declaration is in the constraint position of a mapped type, we infer a 'keyof any' + // constraint. + else if (grandParent.kind === SyntaxKind.TypeParameter && grandParent.parent.kind === SyntaxKind.MappedType) { + inferences = append(inferences, stringNumberSymbolType); + } + // When an 'infer T' declaration is the template of a mapped type, and that mapped type is the extends + // clause of a conditional whose check type is also a mapped type, give it a constraint equal to the template + // of the check type's mapped type + else if ( + grandParent.kind === SyntaxKind.MappedType && (grandParent as MappedTypeNode).type && + skipParentheses((grandParent as MappedTypeNode).type!) === declaration.parent && grandParent.parent.kind === SyntaxKind.ConditionalType && + (grandParent.parent as ConditionalTypeNode).extendsType === grandParent && (grandParent.parent as ConditionalTypeNode).checkType.kind === SyntaxKind.MappedType && + ((grandParent.parent as ConditionalTypeNode).checkType as MappedTypeNode).type + ) { + const checkMappedType = (grandParent.parent as ConditionalTypeNode).checkType as MappedTypeNode; + const nodeType = getTypeFromTypeNode(checkMappedType.type!); + inferences = append(inferences, instantiateType(nodeType, makeUnaryTypeMapper(getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(checkMappedType.typeParameter)), checkMappedType.typeParameter.constraint ? getTypeFromTypeNode(checkMappedType.typeParameter.constraint) : stringNumberSymbolType))); + } + } + } + } + return inferences && getIntersectionType(inferences); + } + + /** This is a worker function. Use getConstraintOfTypeParameter which guards against circular constraints. */ + function getConstraintFromTypeParameter(typeParameter: TypeParameter): Type | undefined { + if (!typeParameter.constraint) { + if (typeParameter.target) { + const targetConstraint = getConstraintOfTypeParameter(typeParameter.target); + typeParameter.constraint = targetConstraint ? instantiateType(targetConstraint, typeParameter.mapper) : noConstraintType; + } + else { + const constraintDeclaration = getConstraintDeclaration(typeParameter); + if (!constraintDeclaration) { + typeParameter.constraint = getInferredTypeParameterConstraint(typeParameter) || noConstraintType; + } + else { + let type = getTypeFromTypeNode(constraintDeclaration); + if (type.flags & TypeFlags.Any && !isErrorType(type)) { // Allow errorType to propegate to keep downstream errors suppressed + // use stringNumberSymbolType as the base constraint for mapped type key constraints (unknown isn;t assignable to that, but `any` was), + // use unknown otherwise + type = constraintDeclaration.parent.parent.kind === SyntaxKind.MappedType ? stringNumberSymbolType : unknownType; + } + typeParameter.constraint = type; + } + } + } + return typeParameter.constraint === noConstraintType ? undefined : typeParameter.constraint; + } + + function getParentSymbolOfTypeParameter(typeParameter: TypeParameter): Symbol | undefined { + const tp = getDeclarationOfKind(typeParameter.symbol, SyntaxKind.TypeParameter)!; + const host = isJSDocTemplateTag(tp.parent) ? getEffectiveContainerForJSDocTemplateTag(tp.parent) : tp.parent; + return host && getSymbolOfNode(host); + } + + function getTypeListId(types: readonly Type[] | undefined) { + let result = ""; + if (types) { + const length = types.length; + let i = 0; + while (i < length) { + const startId = types[i].id; + let count = 1; + while (i + count < length && types[i + count].id === startId + count) { + count++; + } + if (result.length) { + result += ","; + } + result += startId; + if (count > 1) { + result += ":" + count; + } + i += count; + } + } + return result; + } + + function getAliasId(aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { + return aliasSymbol ? `@${getSymbolId(aliasSymbol)}` + (aliasTypeArguments ? `:${getTypeListId(aliasTypeArguments)}` : "") : ""; + } + + // This function is used to propagate certain flags when creating new object type references and union types. + // It is only necessary to do so if a constituent type might be the undefined type, the null type, the type + // of an object literal or a non-inferrable type. This is because there are operations in the type checker + // that care about the presence of such types at arbitrary depth in a containing type. + function getPropagatingFlagsOfTypes(types: readonly Type[], excludeKinds?: TypeFlags): ObjectFlags { + let result: ObjectFlags = 0; + for (const type of types) { + if (excludeKinds === undefined || !(type.flags & excludeKinds)) { + result |= getObjectFlags(type); + } + } + return result & ObjectFlags.PropagatingFlags; + } + + function tryCreateTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined): Type { + if (some(typeArguments) && target === emptyGenericType) { + return unknownType; + } + + return createTypeReference(target, typeArguments); + } + + function createTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined): TypeReference { + const id = getTypeListId(typeArguments); + let type = target.instantiations.get(id); + if (!type) { + type = createObjectType(ObjectFlags.Reference, target.symbol) as TypeReference; + target.instantiations.set(id, type); + type.objectFlags |= typeArguments ? getPropagatingFlagsOfTypes(typeArguments) : 0; + type.target = target; + type.resolvedTypeArguments = typeArguments; + } + return type; + } + + function cloneTypeReference(source: TypeReference): TypeReference { + const type = createTypeWithSymbol(source.flags, source.symbol) as TypeReference; + type.objectFlags = source.objectFlags; + type.target = source.target; + type.resolvedTypeArguments = source.resolvedTypeArguments; + return type; + } + + function createDeferredTypeReference(target: GenericType, node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, mapper?: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): DeferredTypeReference { + if (!aliasSymbol) { + aliasSymbol = getAliasSymbolForTypeNode(node); + const localAliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); + aliasTypeArguments = mapper ? instantiateTypes(localAliasTypeArguments, mapper) : localAliasTypeArguments; + } + const type = createObjectType(ObjectFlags.Reference, target.symbol) as DeferredTypeReference; + type.target = target; + type.node = node; + type.mapper = mapper; + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = aliasTypeArguments; + return type; + } + + function getTypeArguments(type: TypeReference): readonly Type[] { + if (!type.resolvedTypeArguments) { + if (!pushTypeResolution(type, TypeSystemPropertyName.ResolvedTypeArguments)) { + return type.target.localTypeParameters?.map(() => errorType) || emptyArray; + } + const node = type.node; + const typeArguments = !node ? emptyArray : + node.kind === SyntaxKind.TypeReference ? concatenate(type.target.outerTypeParameters, getEffectiveTypeArguments(node, type.target.localTypeParameters!)) : + node.kind === SyntaxKind.ArrayType ? [getTypeFromTypeNode(node.elementType)] : + map(node.elements, getTypeFromTypeNode); + if (popTypeResolution()) { + type.resolvedTypeArguments ??= type.mapper ? instantiateTypes(typeArguments, type.mapper) : typeArguments; + } + else { + type.resolvedTypeArguments ??= type.target.localTypeParameters?.map(() => errorType) || emptyArray; + error( + type.node || currentNode, + type.target.symbol ? Diagnostics.Type_arguments_for_0_circularly_reference_themselves : Diagnostics.Tuple_type_arguments_circularly_reference_themselves, + type.target.symbol && symbolToString(type.target.symbol), + ); + } + } + return type.resolvedTypeArguments; + } + + function getTypeReferenceArity(type: TypeReference): number { + return length(type.target.typeParameters); + } + + /** + * Get type from type-reference that reference to class or interface + */ + function getTypeFromClassOrInterfaceReference(node: NodeWithTypeArguments, symbol: Symbol): Type { + const type = getDeclaredTypeOfSymbol(getMergedSymbol(symbol)) as InterfaceType; + const typeParameters = type.localTypeParameters; + if (typeParameters) { + const numTypeArguments = length(node.typeArguments); + const minTypeArgumentCount = getMinTypeArgumentCount(typeParameters); + const isJs = isInJSFile(node); + const isJsImplicitAny = !noImplicitAny && isJs; + if (!isJsImplicitAny && (numTypeArguments < minTypeArgumentCount || numTypeArguments > typeParameters.length)) { + const missingAugmentsTag = isJs && isExpressionWithTypeArguments(node) && !isJSDocAugmentsTag(node.parent); + const diag = minTypeArgumentCount === typeParameters.length ? + missingAugmentsTag ? + Diagnostics.Expected_0_type_arguments_provide_these_with_an_extends_tag : + Diagnostics.Generic_type_0_requires_1_type_argument_s : + missingAugmentsTag ? + Diagnostics.Expected_0_1_type_arguments_provide_these_with_an_extends_tag : + Diagnostics.Generic_type_0_requires_between_1_and_2_type_arguments; + + const typeStr = typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType); + error(node, diag, typeStr, minTypeArgumentCount, typeParameters.length); + if (!isJs) { + // TODO: Adopt same permissive behavior in TS as in JS to reduce follow-on editing experience failures (requires editing fillMissingTypeArguments) + return errorType; + } + } + if (node.kind === SyntaxKind.TypeReference && isDeferredTypeReferenceNode(node as TypeReferenceNode, length(node.typeArguments) !== typeParameters.length)) { + return createDeferredTypeReference(type as GenericType, node as TypeReferenceNode, /*mapper*/ undefined); + } + // In a type reference, the outer type parameters of the referenced class or interface are automatically + // supplied as type arguments and the type reference only specifies arguments for the local type parameters + // of the class or interface. + const typeArguments = concatenate(type.outerTypeParameters, fillMissingTypeArguments(typeArgumentsFromTypeReferenceNode(node), typeParameters, minTypeArgumentCount, isJs)); + return createTypeReference(type as GenericType, typeArguments); + } + return checkNoTypeArguments(node, symbol) ? type : errorType; + } + + function getTypeAliasInstantiation(symbol: Symbol, typeArguments: readonly Type[] | undefined, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + const type = getDeclaredTypeOfSymbol(symbol); + if (type === intrinsicMarkerType) { + const typeKind = intrinsicTypeKinds.get(symbol.escapedName as string); + if (typeKind !== undefined && typeArguments && typeArguments.length === 1) { + return typeKind === IntrinsicTypeKind.NoInfer ? getNoInferType(typeArguments[0]) : getStringMappingType(symbol, typeArguments[0]); + } + } + const links = getSymbolLinks(symbol); + const typeParameters = links.typeParameters!; + const id = getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments); + let instantiation = links.instantiations!.get(id); + if (!instantiation) { + links.instantiations!.set(id, instantiation = instantiateTypeWithAlias(type, createTypeMapper(typeParameters, fillMissingTypeArguments(typeArguments, typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(symbol.valueDeclaration))), aliasSymbol, aliasTypeArguments)); + } + return instantiation; + } + + /** + * Get type from reference to type alias. When a type alias is generic, the declared type of the type alias may include + * references to the type parameters of the alias. We replace those with the actual type arguments by instantiating the + * declared type. Instantiations are cached using the type identities of the type arguments as the key. + */ + function getTypeFromTypeAliasReference(node: NodeWithTypeArguments, symbol: Symbol): Type { + if (getCheckFlags(symbol) & CheckFlags.Unresolved) { + const typeArguments = typeArgumentsFromTypeReferenceNode(node); + const id = getAliasId(symbol, typeArguments); + let errorType = errorTypes.get(id); + if (!errorType) { + errorType = createIntrinsicType(TypeFlags.Any, "error", /*objectFlags*/ undefined, `alias ${id}`); + errorType.aliasSymbol = symbol; + errorType.aliasTypeArguments = typeArguments; + errorTypes.set(id, errorType); + } + return errorType; + } + const type = getDeclaredTypeOfSymbol(symbol); + const typeParameters = getSymbolLinks(symbol).typeParameters; + if (typeParameters) { + const numTypeArguments = length(node.typeArguments); + const minTypeArgumentCount = getMinTypeArgumentCount(typeParameters); + if (numTypeArguments < minTypeArgumentCount || numTypeArguments > typeParameters.length) { + error( + node, + minTypeArgumentCount === typeParameters.length ? + Diagnostics.Generic_type_0_requires_1_type_argument_s : + Diagnostics.Generic_type_0_requires_between_1_and_2_type_arguments, + symbolToString(symbol), + minTypeArgumentCount, + typeParameters.length, + ); + return errorType; + } + // We refrain from associating a local type alias with an instantiation of a top-level type alias + // because the local alias may end up being referenced in an inferred return type where it is not + // accessible--which in turn may lead to a large structural expansion of the type when generating + // a .d.ts file. See #43622 for an example. + const aliasSymbol = getAliasSymbolForTypeNode(node); + let newAliasSymbol = aliasSymbol && (isLocalTypeAlias(symbol) || !isLocalTypeAlias(aliasSymbol)) ? aliasSymbol : undefined; + let aliasTypeArguments: Type[] | undefined; + if (newAliasSymbol) { + aliasTypeArguments = getTypeArgumentsForAliasSymbol(newAliasSymbol); + } + else if (isTypeReferenceType(node)) { + const aliasSymbol = resolveTypeReferenceName(node, SymbolFlags.Alias, /*ignoreErrors*/ true); + // refers to an alias import/export/reexport - by making sure we use the target as an aliasSymbol, + // we ensure the exported symbol is used to refer to the type when it's reserialized later + if (aliasSymbol && aliasSymbol !== unknownSymbol) { + const resolved = resolveAlias(aliasSymbol); + if (resolved && resolved.flags & SymbolFlags.TypeAlias) { + newAliasSymbol = resolved; + aliasTypeArguments = typeArgumentsFromTypeReferenceNode(node) || (typeParameters ? [] : undefined); + } + } + } + return getTypeAliasInstantiation(symbol, typeArgumentsFromTypeReferenceNode(node), newAliasSymbol, aliasTypeArguments); + } + return checkNoTypeArguments(node, symbol) ? type : errorType; + } + + function isLocalTypeAlias(symbol: Symbol) { + const declaration = symbol.declarations?.find(isTypeAlias); + return !!(declaration && getContainingFunction(declaration)); + } + + function getTypeReferenceName(node: TypeReferenceType): EntityNameOrEntityNameExpression | undefined { + switch (node.kind) { + case SyntaxKind.TypeReference: + return node.typeName; + case SyntaxKind.ExpressionWithTypeArguments: + // We only support expressions that are simple qualified names. For other + // expressions this produces undefined. + const expr = node.expression; + if (isEntityNameExpression(expr)) { + return expr; + } + // fall through; + } + + return undefined; + } + + function getSymbolPath(symbol: Symbol): string { + return symbol.parent ? `${getSymbolPath(symbol.parent)}.${symbol.escapedName}` : symbol.escapedName as string; + } + + function getUnresolvedSymbolForEntityName(name: EntityNameOrEntityNameExpression) { + const identifier = name.kind === SyntaxKind.QualifiedName ? name.right : + name.kind === SyntaxKind.PropertyAccessExpression ? name.name : + name; + const text = identifier.escapedText; + if (text) { + const parentSymbol = name.kind === SyntaxKind.QualifiedName ? getUnresolvedSymbolForEntityName(name.left) : + name.kind === SyntaxKind.PropertyAccessExpression ? getUnresolvedSymbolForEntityName(name.expression) : + undefined; + const path = parentSymbol ? `${getSymbolPath(parentSymbol)}.${text}` : text as string; + let result = unresolvedSymbols.get(path); + if (!result) { + unresolvedSymbols.set(path, result = createSymbol(SymbolFlags.TypeAlias, text, CheckFlags.Unresolved)); + result.parent = parentSymbol; + result.links.declaredType = unresolvedType; + } + return result; + } + return unknownSymbol; + } + + function resolveTypeReferenceName(typeReference: TypeReferenceType, meaning: SymbolFlags, ignoreErrors?: boolean) { + const name = getTypeReferenceName(typeReference); + if (!name) { + return unknownSymbol; + } + const symbol = resolveEntityName(name, meaning, ignoreErrors); + return symbol && symbol !== unknownSymbol ? symbol : + ignoreErrors ? unknownSymbol : getUnresolvedSymbolForEntityName(name); + } + + function getTypeReferenceType(node: NodeWithTypeArguments, symbol: Symbol): Type { + if (symbol === unknownSymbol) { + return errorType; + } + symbol = getExpandoSymbol(symbol) || symbol; + if (symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) { + return getTypeFromClassOrInterfaceReference(node, symbol); + } + if (symbol.flags & SymbolFlags.TypeAlias) { + return getTypeFromTypeAliasReference(node, symbol); + } + // Get type from reference to named type that cannot be generic (enum or type parameter) + const res = tryGetDeclaredTypeOfSymbol(symbol); + if (res) { + return checkNoTypeArguments(node, symbol) ? getRegularTypeOfLiteralType(res) : errorType; + } + if (symbol.flags & SymbolFlags.Value && isJSDocTypeReference(node)) { + const jsdocType = getTypeFromJSDocValueReference(node, symbol); + if (jsdocType) { + return jsdocType; + } + else { + // Resolve the type reference as a Type for the purpose of reporting errors. + resolveTypeReferenceName(node, SymbolFlags.Type); + return getTypeOfSymbol(symbol); + } + } + return errorType; + } + + /** + * A JSdoc TypeReference may be to a value, but resolve it as a type anyway. + * Example: import('./b').ConstructorFunction + */ + function getTypeFromJSDocValueReference(node: NodeWithTypeArguments, symbol: Symbol): Type | undefined { + const links = getNodeLinks(node); + if (!links.resolvedJSDocType) { + const valueType = getTypeOfSymbol(symbol); + let typeType = valueType; + if (symbol.valueDeclaration) { + const isImportTypeWithQualifier = node.kind === SyntaxKind.ImportType && (node as ImportTypeNode).qualifier; + // valueType might not have a symbol, eg, {import('./b').STRING_LITERAL} + if (valueType.symbol && valueType.symbol !== symbol && isImportTypeWithQualifier) { + typeType = getTypeReferenceType(node, valueType.symbol); + } + } + links.resolvedJSDocType = typeType; + } + return links.resolvedJSDocType; + } + + function getNoInferType(type: Type) { + return isNoInferTargetType(type) ? getOrCreateSubstitutionType(type, unknownType) : type; + } + + function isNoInferTargetType(type: Type): boolean { + // This is effectively a more conservative and predictable form of couldContainTypeVariables. We want to + // preserve NoInfer only for types that could contain type variables, but we don't want to exhaustively + // examine all object type members. + return !!(type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, isNoInferTargetType) || + type.flags & TypeFlags.Substitution && !isNoInferType(type) && isNoInferTargetType((type as SubstitutionType).baseType) || + type.flags & TypeFlags.Object && !isEmptyAnonymousObjectType(type) || + type.flags & (TypeFlags.Instantiable & ~TypeFlags.Substitution) && !isPatternLiteralType(type)); + } + + function isNoInferType(type: Type) { + // A NoInfer type is represented as a substitution type with a TypeFlags.Unknown constraint. + return !!(type.flags & TypeFlags.Substitution && (type as SubstitutionType).constraint.flags & TypeFlags.Unknown); + } + + function getSubstitutionType(baseType: Type, constraint: Type) { + return constraint.flags & TypeFlags.AnyOrUnknown || constraint === baseType || baseType.flags & TypeFlags.Any ? + baseType : + getOrCreateSubstitutionType(baseType, constraint); + } + + function getOrCreateSubstitutionType(baseType: Type, constraint: Type) { + const id = `${getTypeId(baseType)}>${getTypeId(constraint)}`; + const cached = substitutionTypes.get(id); + if (cached) { + return cached; + } + const result = createType(TypeFlags.Substitution) as SubstitutionType; + result.baseType = baseType; + result.constraint = constraint; + substitutionTypes.set(id, result); + return result; + } + + function getSubstitutionIntersection(substitutionType: SubstitutionType) { + return isNoInferType(substitutionType) ? substitutionType.baseType : getIntersectionType([substitutionType.constraint, substitutionType.baseType]); + } + + function isUnaryTupleTypeNode(node: TypeNode) { + return node.kind === SyntaxKind.TupleType && (node as TupleTypeNode).elements.length === 1; + } + + function getImpliedConstraint(type: Type, checkNode: TypeNode, extendsNode: TypeNode): Type | undefined { + return isUnaryTupleTypeNode(checkNode) && isUnaryTupleTypeNode(extendsNode) ? getImpliedConstraint(type, (checkNode as TupleTypeNode).elements[0], (extendsNode as TupleTypeNode).elements[0]) : + getActualTypeVariable(getTypeFromTypeNode(checkNode)) === getActualTypeVariable(type) ? getTypeFromTypeNode(extendsNode) : + undefined; + } + + function getConditionalFlowTypeOfType(type: Type, node: Node) { + let constraints: Type[] | undefined; + let covariant = true; + while (node && !isStatement(node) && node.kind !== SyntaxKind.JSDoc) { + const parent = node.parent; + // only consider variance flipped by parameter locations - `keyof` types would usually be considered variance inverting, but + // often get used in indexed accesses where they behave sortof invariantly, but our checking is lax + if (parent.kind === SyntaxKind.Parameter) { + covariant = !covariant; + } + // Always substitute on type parameters, regardless of variance, since even + // in contravariant positions, they may rely on substituted constraints to be valid + if ((covariant || type.flags & TypeFlags.TypeVariable) && parent.kind === SyntaxKind.ConditionalType && node === (parent as ConditionalTypeNode).trueType) { + const constraint = getImpliedConstraint(type, (parent as ConditionalTypeNode).checkType, (parent as ConditionalTypeNode).extendsType); + if (constraint) { + constraints = append(constraints, constraint); + } + } + // Given a homomorphic mapped type { [K in keyof T]: XXX }, where T is constrained to an array or tuple type, in the + // template type XXX, K has an added constraint of number | `${number}`. + else if (type.flags & TypeFlags.TypeParameter && parent.kind === SyntaxKind.MappedType && !(parent as MappedTypeNode).nameType && node === (parent as MappedTypeNode).type) { + const mappedType = getTypeFromTypeNode(parent as TypeNode) as MappedType; + if (getTypeParameterFromMappedType(mappedType) === getActualTypeVariable(type)) { + const typeParameter = getHomomorphicTypeVariable(mappedType); + if (typeParameter) { + const constraint = getConstraintOfTypeParameter(typeParameter); + if (constraint && everyType(constraint, isArrayOrTupleType)) { + constraints = append(constraints, getUnionType([numberType, numericStringType])); + } + } + } + } + node = parent; + } + return constraints ? getSubstitutionType(type, getIntersectionType(constraints)) : type; + } + + function isJSDocTypeReference(node: Node): node is TypeReferenceNode { + return !!(node.flags & NodeFlags.JSDoc) && (node.kind === SyntaxKind.TypeReference || node.kind === SyntaxKind.ImportType); + } + + function checkNoTypeArguments(node: NodeWithTypeArguments, symbol?: Symbol) { + if (node.typeArguments) { + error(node, Diagnostics.Type_0_is_not_generic, symbol ? symbolToString(symbol) : (node as TypeReferenceNode).typeName ? declarationNameToString((node as TypeReferenceNode).typeName) : anon); + return false; + } + return true; + } + + function getIntendedTypeFromJSDocTypeReference(node: TypeReferenceNode): Type | undefined { + if (isIdentifier(node.typeName)) { + const typeArgs = node.typeArguments; + switch (node.typeName.escapedText) { + case "String": + checkNoTypeArguments(node); + return stringType; + case "Number": + checkNoTypeArguments(node); + return numberType; + case "Boolean": + checkNoTypeArguments(node); + return booleanType; + case "Void": + checkNoTypeArguments(node); + return voidType; + case "Undefined": + checkNoTypeArguments(node); + return undefinedType; + case "Null": + checkNoTypeArguments(node); + return nullType; + case "Function": + case "function": + checkNoTypeArguments(node); + return globalFunctionType; + case "array": + return (!typeArgs || !typeArgs.length) && !noImplicitAny ? anyArrayType : undefined; + case "promise": + return (!typeArgs || !typeArgs.length) && !noImplicitAny ? createPromiseType(anyType) : undefined; + case "Object": + if (typeArgs && typeArgs.length === 2) { + if (isJSDocIndexSignature(node)) { + const indexed = getTypeFromTypeNode(typeArgs[0]); + const target = getTypeFromTypeNode(typeArgs[1]); + const indexInfo = indexed === stringType || indexed === numberType ? [createIndexInfo(indexed, target, /*isReadonly*/ false)] : emptyArray; + return createAnonymousType(/*symbol*/ undefined, emptySymbols, emptyArray, emptyArray, indexInfo); + } + return anyType; + } + checkNoTypeArguments(node); + return !noImplicitAny ? anyType : undefined; + } + } + } + + function getTypeFromJSDocNullableTypeNode(node: JSDocNullableType) { + const type = getTypeFromTypeNode(node.type); + return strictNullChecks ? getNullableType(type, TypeFlags.Null) : type; + } + + function getTypeFromTypeReference(node: TypeReferenceType): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + // handle LS queries on the `const` in `x as const` by resolving to the type of `x` + if (isConstTypeReference(node) && isAssertionExpression(node.parent)) { + links.resolvedSymbol = unknownSymbol; + return links.resolvedType = checkExpressionCached(node.parent.expression); + } + let symbol: Symbol | undefined; + let type: Type | undefined; + const meaning = SymbolFlags.Type; + if (isJSDocTypeReference(node)) { + type = getIntendedTypeFromJSDocTypeReference(node); + if (!type) { + symbol = resolveTypeReferenceName(node, meaning, /*ignoreErrors*/ true); + if (symbol === unknownSymbol) { + symbol = resolveTypeReferenceName(node, meaning | SymbolFlags.Value); + } + else { + resolveTypeReferenceName(node, meaning); // Resolve again to mark errors, if any + } + type = getTypeReferenceType(node, symbol); + } + } + if (!type) { + symbol = resolveTypeReferenceName(node, meaning); + type = getTypeReferenceType(node, symbol); + } + // Cache both the resolved symbol and the resolved type. The resolved symbol is needed when we check the + // type reference in checkTypeReferenceNode. + links.resolvedSymbol = symbol; + links.resolvedType = type; + } + return links.resolvedType; + } + + function typeArgumentsFromTypeReferenceNode(node: NodeWithTypeArguments): Type[] | undefined { + return map(node.typeArguments, getTypeFromTypeNode); + } + + function getTypeFromTypeQueryNode(node: TypeQueryNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + // TypeScript 1.0 spec (April 2014): 3.6.3 + // The expression is processed as an identifier expression (section 4.3) + // or property access expression(section 4.10), + // the widened type(section 3.9) of which becomes the result. + const type = checkExpressionWithTypeArguments(node); + links.resolvedType = getRegularTypeOfLiteralType(getWidenedType(type)); + } + return links.resolvedType; + } + + function getTypeOfGlobalSymbol(symbol: Symbol | undefined, arity: number): ObjectType { + function getTypeDeclaration(symbol: Symbol): Declaration | undefined { + const declarations = symbol.declarations; + if (declarations) { + for (const declaration of declarations) { + switch (declaration.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.EnumDeclaration: + return declaration; + } + } + } + } + + if (!symbol) { + return arity ? emptyGenericType : emptyObjectType; + } + const type = getDeclaredTypeOfSymbol(symbol); + if (!(type.flags & TypeFlags.Object)) { + error(getTypeDeclaration(symbol), Diagnostics.Global_type_0_must_be_a_class_or_interface_type, symbolName(symbol)); + return arity ? emptyGenericType : emptyObjectType; + } + if (length((type as InterfaceType).typeParameters) !== arity) { + error(getTypeDeclaration(symbol), Diagnostics.Global_type_0_must_have_1_type_parameter_s, symbolName(symbol), arity); + return arity ? emptyGenericType : emptyObjectType; + } + return type as ObjectType; + } + + function getGlobalValueSymbol(name: __String, reportErrors: boolean): Symbol | undefined { + return getGlobalSymbol(name, SymbolFlags.Value, reportErrors ? Diagnostics.Cannot_find_global_value_0 : undefined); + } + + function getGlobalTypeSymbol(name: __String, reportErrors: boolean): Symbol | undefined { + return getGlobalSymbol(name, SymbolFlags.Type, reportErrors ? Diagnostics.Cannot_find_global_type_0 : undefined); + } + + function getGlobalTypeAliasSymbol(name: __String, arity: number, reportErrors: boolean): Symbol | undefined { + const symbol = getGlobalSymbol(name, SymbolFlags.Type, reportErrors ? Diagnostics.Cannot_find_global_type_0 : undefined); + if (symbol) { + // Resolve the declared type of the symbol. This resolves type parameters for the type + // alias so that we can check arity. + getDeclaredTypeOfSymbol(symbol); + if (length(getSymbolLinks(symbol).typeParameters) !== arity) { + const decl = symbol.declarations && find(symbol.declarations, isTypeAliasDeclaration); + error(decl, Diagnostics.Global_type_0_must_have_1_type_parameter_s, symbolName(symbol), arity); + return undefined; + } + } + return symbol; + } + + function getGlobalSymbol(name: __String, meaning: SymbolFlags, diagnostic: DiagnosticMessage | undefined): Symbol | undefined { + // Don't track references for global symbols anyway, so value if `isReference` is arbitrary + return resolveName(/*location*/ undefined, name, meaning, diagnostic, /*isUse*/ false, /*excludeGlobals*/ false); + } + + function getGlobalType(name: __String, arity: 0, reportErrors: true): ObjectType; + function getGlobalType(name: __String, arity: 0, reportErrors: boolean): ObjectType | undefined; + function getGlobalType(name: __String, arity: number, reportErrors: true): GenericType; + function getGlobalType(name: __String, arity: number, reportErrors: boolean): GenericType | undefined; + function getGlobalType(name: __String, arity: number, reportErrors: boolean): ObjectType | undefined { + const symbol = getGlobalTypeSymbol(name, reportErrors); + return symbol || reportErrors ? getTypeOfGlobalSymbol(symbol, arity) : undefined; + } + + function getGlobalTypedPropertyDescriptorType() { + // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times + return deferredGlobalTypedPropertyDescriptorType ||= getGlobalType("TypedPropertyDescriptor" as __String, /*arity*/ 1, /*reportErrors*/ true) || emptyGenericType; + } + + function getGlobalTemplateStringsArrayType() { + // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times + return deferredGlobalTemplateStringsArrayType ||= getGlobalType("TemplateStringsArray" as __String, /*arity*/ 0, /*reportErrors*/ true) || emptyObjectType; + } + + function getGlobalImportMetaType() { + // We always report an error, so store a result in the event we could not resolve the symbol to prevent reporting it multiple times + return deferredGlobalImportMetaType ||= getGlobalType("ImportMeta" as __String, /*arity*/ 0, /*reportErrors*/ true) || emptyObjectType; + } + + function getGlobalImportMetaExpressionType() { + if (!deferredGlobalImportMetaExpressionType) { + // Create a synthetic type `ImportMetaExpression { meta: MetaProperty }` + const symbol = createSymbol(SymbolFlags.None, "ImportMetaExpression" as __String); + const importMetaType = getGlobalImportMetaType(); + + const metaPropertySymbol = createSymbol(SymbolFlags.Property, "meta" as __String, CheckFlags.Readonly); + metaPropertySymbol.parent = symbol; + metaPropertySymbol.links.type = importMetaType; + + const members = createSymbolTable([metaPropertySymbol]); + symbol.members = members; + + deferredGlobalImportMetaExpressionType = createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + } + return deferredGlobalImportMetaExpressionType; + } + + function getGlobalImportCallOptionsType(reportErrors: boolean) { + return (deferredGlobalImportCallOptionsType ||= getGlobalType("ImportCallOptions" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalImportAttributesType(reportErrors: boolean) { + return (deferredGlobalImportAttributesType ||= getGlobalType("ImportAttributes" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalESSymbolConstructorSymbol(reportErrors: boolean): Symbol | undefined { + return deferredGlobalESSymbolConstructorSymbol ||= getGlobalValueSymbol("Symbol" as __String, reportErrors); + } + + function getGlobalESSymbolConstructorTypeSymbol(reportErrors: boolean): Symbol | undefined { + return deferredGlobalESSymbolConstructorTypeSymbol ||= getGlobalTypeSymbol("SymbolConstructor" as __String, reportErrors); + } + + function getGlobalESSymbolType() { + return (deferredGlobalESSymbolType ||= getGlobalType("Symbol" as __String, /*arity*/ 0, /*reportErrors*/ false)) || emptyObjectType; + } + + function getGlobalPromiseType(reportErrors: boolean) { + return (deferredGlobalPromiseType ||= getGlobalType("Promise" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalPromiseLikeType(reportErrors: boolean) { + return (deferredGlobalPromiseLikeType ||= getGlobalType("PromiseLike" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalPromiseConstructorSymbol(reportErrors: boolean): Symbol | undefined { + return deferredGlobalPromiseConstructorSymbol ||= getGlobalValueSymbol("Promise" as __String, reportErrors); + } + + function getGlobalPromiseConstructorLikeType(reportErrors: boolean) { + return (deferredGlobalPromiseConstructorLikeType ||= getGlobalType("PromiseConstructorLike" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalAsyncIterableType(reportErrors: boolean) { + return (deferredGlobalAsyncIterableType ||= getGlobalType("AsyncIterable" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalAsyncIteratorType(reportErrors: boolean) { + return (deferredGlobalAsyncIteratorType ||= getGlobalType("AsyncIterator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalAsyncIterableIteratorType(reportErrors: boolean) { + return (deferredGlobalAsyncIterableIteratorType ||= getGlobalType("AsyncIterableIterator" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalAsyncGeneratorType(reportErrors: boolean) { + return (deferredGlobalAsyncGeneratorType ||= getGlobalType("AsyncGenerator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalIterableType(reportErrors: boolean) { + return (deferredGlobalIterableType ||= getGlobalType("Iterable" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalIteratorType(reportErrors: boolean) { + return (deferredGlobalIteratorType ||= getGlobalType("Iterator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalIterableIteratorType(reportErrors: boolean) { + return (deferredGlobalIterableIteratorType ||= getGlobalType("IterableIterator" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalGeneratorType(reportErrors: boolean) { + return (deferredGlobalGeneratorType ||= getGlobalType("Generator" as __String, /*arity*/ 3, reportErrors)) || emptyGenericType; + } + + function getGlobalIteratorYieldResultType(reportErrors: boolean) { + return (deferredGlobalIteratorYieldResultType ||= getGlobalType("IteratorYieldResult" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalIteratorReturnResultType(reportErrors: boolean) { + return (deferredGlobalIteratorReturnResultType ||= getGlobalType("IteratorReturnResult" as __String, /*arity*/ 1, reportErrors)) || emptyGenericType; + } + + function getGlobalDisposableType(reportErrors: boolean) { + return (deferredGlobalDisposableType ||= getGlobalType("Disposable" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalAsyncDisposableType(reportErrors: boolean) { + return (deferredGlobalAsyncDisposableType ||= getGlobalType("AsyncDisposable" as __String, /*arity*/ 0, reportErrors)) || emptyObjectType; + } + + function getGlobalTypeOrUndefined(name: __String, arity = 0): ObjectType | undefined { + const symbol = getGlobalSymbol(name, SymbolFlags.Type, /*diagnostic*/ undefined); + return symbol && getTypeOfGlobalSymbol(symbol, arity) as GenericType; + } + + function getGlobalExtractSymbol(): Symbol | undefined { + // We always report an error, so cache a result in the event we could not resolve the symbol to prevent reporting it multiple times + deferredGlobalExtractSymbol ||= getGlobalTypeAliasSymbol("Extract" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; + return deferredGlobalExtractSymbol === unknownSymbol ? undefined : deferredGlobalExtractSymbol; + } + + function getGlobalOmitSymbol(): Symbol | undefined { + // We always report an error, so cache a result in the event we could not resolve the symbol to prevent reporting it multiple times + deferredGlobalOmitSymbol ||= getGlobalTypeAliasSymbol("Omit" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; + return deferredGlobalOmitSymbol === unknownSymbol ? undefined : deferredGlobalOmitSymbol; + } + + function getGlobalAwaitedSymbol(reportErrors: boolean): Symbol | undefined { + // Only cache `unknownSymbol` if we are reporting errors so that we don't report the error more than once. + deferredGlobalAwaitedSymbol ||= getGlobalTypeAliasSymbol("Awaited" as __String, /*arity*/ 1, reportErrors) || (reportErrors ? unknownSymbol : undefined); + return deferredGlobalAwaitedSymbol === unknownSymbol ? undefined : deferredGlobalAwaitedSymbol; + } + + function getGlobalBigIntType() { + return (deferredGlobalBigIntType ||= getGlobalType("BigInt" as __String, /*arity*/ 0, /*reportErrors*/ false)) || emptyObjectType; + } + + function getGlobalClassDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassDecoratorContextType ??= getGlobalType("ClassDecoratorContext" as __String, /*arity*/ 1, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassMethodDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassMethodDecoratorContextType ??= getGlobalType("ClassMethodDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassGetterDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassGetterDecoratorContextType ??= getGlobalType("ClassGetterDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassSetterDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassSetterDecoratorContextType ??= getGlobalType("ClassSetterDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassAccessorDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassAccessorDecoratorContextType ??= getGlobalType("ClassAccessorDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassAccessorDecoratorTargetType(reportErrors: boolean) { + return (deferredGlobalClassAccessorDecoratorTargetType ??= getGlobalType("ClassAccessorDecoratorTarget" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassAccessorDecoratorResultType(reportErrors: boolean) { + return (deferredGlobalClassAccessorDecoratorResultType ??= getGlobalType("ClassAccessorDecoratorResult" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalClassFieldDecoratorContextType(reportErrors: boolean) { + return (deferredGlobalClassFieldDecoratorContextType ??= getGlobalType("ClassFieldDecoratorContext" as __String, /*arity*/ 2, reportErrors)) ?? emptyGenericType; + } + + function getGlobalNaNSymbol(): Symbol | undefined { + return (deferredGlobalNaNSymbol ||= getGlobalValueSymbol("NaN" as __String, /*reportErrors*/ false)); + } + + function getGlobalRecordSymbol(): Symbol | undefined { + deferredGlobalRecordSymbol ||= getGlobalTypeAliasSymbol("Record" as __String, /*arity*/ 2, /*reportErrors*/ true) || unknownSymbol; + return deferredGlobalRecordSymbol === unknownSymbol ? undefined : deferredGlobalRecordSymbol; + } + + /** + * Instantiates a global type that is generic with some element type, and returns that instantiation. + */ + function createTypeFromGenericGlobalType(genericGlobalType: GenericType, typeArguments: readonly Type[]): ObjectType { + return genericGlobalType !== emptyGenericType ? createTypeReference(genericGlobalType, typeArguments) : emptyObjectType; + } + + function createTypedPropertyDescriptorType(propertyType: Type): Type { + return createTypeFromGenericGlobalType(getGlobalTypedPropertyDescriptorType(), [propertyType]); + } + + function createIterableType(iteratedType: Type): Type { + return createTypeFromGenericGlobalType(getGlobalIterableType(/*reportErrors*/ true), [iteratedType]); + } + + function createArrayType(elementType: Type, readonly?: boolean): ObjectType { + return createTypeFromGenericGlobalType(readonly ? globalReadonlyArrayType : globalArrayType, [elementType]); + } + + function getTupleElementFlags(node: TypeNode) { + switch (node.kind) { + case SyntaxKind.OptionalType: + return ElementFlags.Optional; + case SyntaxKind.RestType: + return getRestTypeElementFlags(node as RestTypeNode); + case SyntaxKind.NamedTupleMember: + return (node as NamedTupleMember).questionToken ? ElementFlags.Optional : + (node as NamedTupleMember).dotDotDotToken ? getRestTypeElementFlags(node as NamedTupleMember) : + ElementFlags.Required; + default: + return ElementFlags.Required; + } + } + + function getRestTypeElementFlags(node: RestTypeNode | NamedTupleMember) { + return getArrayElementTypeNode(node.type) ? ElementFlags.Rest : ElementFlags.Variadic; + } + + function getArrayOrTupleTargetType(node: ArrayTypeNode | TupleTypeNode): GenericType { + const readonly = isReadonlyTypeOperator(node.parent); + const elementType = getArrayElementTypeNode(node); + if (elementType) { + return readonly ? globalReadonlyArrayType : globalArrayType; + } + const elementFlags = map((node as TupleTypeNode).elements, getTupleElementFlags); + return getTupleTargetType(elementFlags, readonly, map((node as TupleTypeNode).elements, memberIfLabeledElementDeclaration)); + } + + function memberIfLabeledElementDeclaration(member: Node): NamedTupleMember | ParameterDeclaration | undefined { + return isNamedTupleMember(member) || isParameter(member) ? member : undefined; + } + + // Return true if the given type reference node is directly aliased or if it needs to be deferred + // because it is possibly contained in a circular chain of eagerly resolved types. + function isDeferredTypeReferenceNode(node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, hasDefaultTypeArguments?: boolean) { + return !!getAliasSymbolForTypeNode(node) || isResolvedByTypeAlias(node) && ( + node.kind === SyntaxKind.ArrayType ? mayResolveTypeAlias(node.elementType) : + node.kind === SyntaxKind.TupleType ? some(node.elements, mayResolveTypeAlias) : + hasDefaultTypeArguments || some(node.typeArguments, mayResolveTypeAlias) + ); + } + + // Return true when the given node is transitively contained in type constructs that eagerly + // resolve their constituent types. We include SyntaxKind.TypeReference because type arguments + // of type aliases are eagerly resolved. + function isResolvedByTypeAlias(node: Node): boolean { + const parent = node.parent; + switch (parent.kind) { + case SyntaxKind.ParenthesizedType: + case SyntaxKind.NamedTupleMember: + case SyntaxKind.TypeReference: + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + case SyntaxKind.IndexedAccessType: + case SyntaxKind.ConditionalType: + case SyntaxKind.TypeOperator: + case SyntaxKind.ArrayType: + case SyntaxKind.TupleType: + return isResolvedByTypeAlias(parent); + case SyntaxKind.TypeAliasDeclaration: + return true; + } + return false; + } + + // Return true if resolving the given node (i.e. getTypeFromTypeNode) possibly causes resolution + // of a type alias. + function mayResolveTypeAlias(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.TypeReference: + return isJSDocTypeReference(node) || !!(resolveTypeReferenceName(node as TypeReferenceNode, SymbolFlags.Type).flags & SymbolFlags.TypeAlias); + case SyntaxKind.TypeQuery: + return true; + case SyntaxKind.TypeOperator: + return (node as TypeOperatorNode).operator !== SyntaxKind.UniqueKeyword && mayResolveTypeAlias((node as TypeOperatorNode).type); + case SyntaxKind.ParenthesizedType: + case SyntaxKind.OptionalType: + case SyntaxKind.NamedTupleMember: + case SyntaxKind.JSDocOptionalType: + case SyntaxKind.JSDocNullableType: + case SyntaxKind.JSDocNonNullableType: + case SyntaxKind.JSDocTypeExpression: + return mayResolveTypeAlias((node as ParenthesizedTypeNode | OptionalTypeNode | JSDocTypeReferencingNode | NamedTupleMember).type); + case SyntaxKind.RestType: + return (node as RestTypeNode).type.kind !== SyntaxKind.ArrayType || mayResolveTypeAlias(((node as RestTypeNode).type as ArrayTypeNode).elementType); + case SyntaxKind.UnionType: + case SyntaxKind.IntersectionType: + return some((node as UnionOrIntersectionTypeNode).types, mayResolveTypeAlias); + case SyntaxKind.IndexedAccessType: + return mayResolveTypeAlias((node as IndexedAccessTypeNode).objectType) || mayResolveTypeAlias((node as IndexedAccessTypeNode).indexType); + case SyntaxKind.ConditionalType: + return mayResolveTypeAlias((node as ConditionalTypeNode).checkType) || mayResolveTypeAlias((node as ConditionalTypeNode).extendsType) || + mayResolveTypeAlias((node as ConditionalTypeNode).trueType) || mayResolveTypeAlias((node as ConditionalTypeNode).falseType); + } + return false; + } + + function getTypeFromArrayOrTupleTypeNode(node: ArrayTypeNode | TupleTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const target = getArrayOrTupleTargetType(node); + if (target === emptyGenericType) { + links.resolvedType = emptyObjectType; + } + else if (!(node.kind === SyntaxKind.TupleType && some(node.elements, e => !!(getTupleElementFlags(e) & ElementFlags.Variadic))) && isDeferredTypeReferenceNode(node)) { + links.resolvedType = node.kind === SyntaxKind.TupleType && node.elements.length === 0 ? target : + createDeferredTypeReference(target, node, /*mapper*/ undefined); + } + else { + const elementTypes = node.kind === SyntaxKind.ArrayType ? [getTypeFromTypeNode(node.elementType)] : map(node.elements, getTypeFromTypeNode); + links.resolvedType = createNormalizedTypeReference(target, elementTypes); + } + } + return links.resolvedType; + } + + function isReadonlyTypeOperator(node: Node) { + return isTypeOperatorNode(node) && node.operator === SyntaxKind.ReadonlyKeyword; + } + + function createTupleType(elementTypes: readonly Type[], elementFlags?: readonly ElementFlags[], readonly = false, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration | undefined)[] = []) { + const tupleTarget = getTupleTargetType(elementFlags || map(elementTypes, _ => ElementFlags.Required), readonly, namedMemberDeclarations); + return tupleTarget === emptyGenericType ? emptyObjectType : + elementTypes.length ? createNormalizedTypeReference(tupleTarget, elementTypes) : + tupleTarget; + } + + function getTupleTargetType(elementFlags: readonly ElementFlags[], readonly: boolean, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration | undefined)[]): GenericType { + if (elementFlags.length === 1 && elementFlags[0] & ElementFlags.Rest) { + // [...X[]] is equivalent to just X[] + return readonly ? globalReadonlyArrayType : globalArrayType; + } + const key = map(elementFlags, f => f & ElementFlags.Required ? "#" : f & ElementFlags.Optional ? "?" : f & ElementFlags.Rest ? "." : "*").join() + + (readonly ? "R" : "") + + (some(namedMemberDeclarations, node => !!node) ? "," + map(namedMemberDeclarations, node => node ? getNodeId(node) : "_").join(",") : ""); + let type = tupleTypes.get(key); + if (!type) { + tupleTypes.set(key, type = createTupleTargetType(elementFlags, readonly, namedMemberDeclarations)); + } + return type; + } + + // We represent tuple types as type references to synthesized generic interface types created by + // this function. The types are of the form: + // + // interface Tuple extends Array { 0: T0, 1: T1, 2: T2, ... } + // + // Note that the generic type created by this function has no symbol associated with it. The same + // is true for each of the synthesized type parameters. + function createTupleTargetType(elementFlags: readonly ElementFlags[], readonly: boolean, namedMemberDeclarations: readonly (NamedTupleMember | ParameterDeclaration | undefined)[]): TupleType { + const arity = elementFlags.length; + const minLength = countWhere(elementFlags, f => !!(f & (ElementFlags.Required | ElementFlags.Variadic))); + let typeParameters: TypeParameter[] | undefined; + const properties: Symbol[] = []; + let combinedFlags = 0 as ElementFlags; + if (arity) { + typeParameters = new Array(arity); + for (let i = 0; i < arity; i++) { + const typeParameter = typeParameters[i] = createTypeParameter(); + const flags = elementFlags[i]; + combinedFlags |= flags; + if (!(combinedFlags & ElementFlags.Variable)) { + const property = createSymbol(SymbolFlags.Property | (flags & ElementFlags.Optional ? SymbolFlags.Optional : 0), "" + i as __String, readonly ? CheckFlags.Readonly : 0); + property.links.tupleLabelDeclaration = namedMemberDeclarations?.[i]; + property.links.type = typeParameter; + properties.push(property); + } + } + } + const fixedLength = properties.length; + const lengthSymbol = createSymbol(SymbolFlags.Property, "length" as __String, readonly ? CheckFlags.Readonly : 0); + if (combinedFlags & ElementFlags.Variable) { + lengthSymbol.links.type = numberType; + } + else { + const literalTypes = []; + for (let i = minLength; i <= arity; i++) literalTypes.push(getNumberLiteralType(i)); + lengthSymbol.links.type = getUnionType(literalTypes); + } + properties.push(lengthSymbol); + const type = createObjectType(ObjectFlags.Tuple | ObjectFlags.Reference) as TupleType & InterfaceTypeWithDeclaredMembers; + type.typeParameters = typeParameters; + type.outerTypeParameters = undefined; + type.localTypeParameters = typeParameters; + type.instantiations = new Map(); + type.instantiations.set(getTypeListId(type.typeParameters), type as GenericType); + type.target = type as GenericType; + type.resolvedTypeArguments = type.typeParameters; + type.thisType = createTypeParameter(); + type.thisType.isThisType = true; + type.thisType.constraint = type; + type.declaredProperties = properties; + type.declaredCallSignatures = emptyArray; + type.declaredConstructSignatures = emptyArray; + type.declaredIndexInfos = emptyArray; + type.elementFlags = elementFlags; + type.minLength = minLength; + type.fixedLength = fixedLength; + type.hasRestElement = !!(combinedFlags & ElementFlags.Variable); + type.combinedFlags = combinedFlags; + type.readonly = readonly; + type.labeledElementDeclarations = namedMemberDeclarations; + return type; + } + + function createNormalizedTypeReference(target: GenericType, typeArguments: readonly Type[] | undefined) { + return target.objectFlags & ObjectFlags.Tuple ? createNormalizedTupleType(target as TupleType, typeArguments!) : createTypeReference(target, typeArguments); + } + + function createNormalizedTupleType(target: TupleType, elementTypes: readonly Type[]): Type { + if (!(target.combinedFlags & ElementFlags.NonRequired)) { + // No need to normalize when we only have regular required elements + return createTypeReference(target, elementTypes); + } + if (target.combinedFlags & ElementFlags.Variadic) { + // Transform [A, ...(X | Y | Z)] into [A, ...X] | [A, ...Y] | [A, ...Z] + const unionIndex = findIndex(elementTypes, (t, i) => !!(target.elementFlags[i] & ElementFlags.Variadic && t.flags & (TypeFlags.Never | TypeFlags.Union))); + if (unionIndex >= 0) { + return checkCrossProductUnion(map(elementTypes, (t, i) => target.elementFlags[i] & ElementFlags.Variadic ? t : unknownType)) ? + mapType(elementTypes[unionIndex], t => createNormalizedTupleType(target, replaceElement(elementTypes, unionIndex, t))) : + errorType; + } + } + // We have optional, rest, or variadic elements that may need normalizing. Normalization ensures that all variadic + // elements are generic and that the tuple type has one of the following layouts, disregarding variadic elements: + // (1) Zero or more required elements, followed by zero or more optional elements, followed by zero or one rest element. + // (2) Zero or more required elements, followed by a rest element, followed by zero or more required elements. + // In either layout, zero or more generic variadic elements may be present at any location. + const expandedTypes: Type[] = []; + const expandedFlags: ElementFlags[] = []; + const expandedDeclarations: (NamedTupleMember | ParameterDeclaration | undefined)[] = []; + let lastRequiredIndex = -1; + let firstRestIndex = -1; + let lastOptionalOrRestIndex = -1; + for (let i = 0; i < elementTypes.length; i++) { + const type = elementTypes[i]; + const flags = target.elementFlags[i]; + if (flags & ElementFlags.Variadic) { + if (type.flags & TypeFlags.Any) { + addElement(type, ElementFlags.Rest, target.labeledElementDeclarations?.[i]); + } + else if (type.flags & TypeFlags.InstantiableNonPrimitive || isGenericMappedType(type)) { + // Generic variadic elements stay as they are. + addElement(type, ElementFlags.Variadic, target.labeledElementDeclarations?.[i]); + } + else if (isTupleType(type)) { + const elements = getElementTypes(type); + if (elements.length + expandedTypes.length >= 10_000) { + error( + currentNode, + isPartOfTypeNode(currentNode!) + ? Diagnostics.Type_produces_a_tuple_type_that_is_too_large_to_represent + : Diagnostics.Expression_produces_a_tuple_type_that_is_too_large_to_represent, + ); + return errorType; + } + // Spread variadic elements with tuple types into the resulting tuple. + forEach(elements, (t, n) => addElement(t, type.target.elementFlags[n], type.target.labeledElementDeclarations?.[n])); + } + else { + // Treat everything else as an array type and create a rest element. + addElement(isArrayLikeType(type) && getIndexTypeOfType(type, numberType) || errorType, ElementFlags.Rest, target.labeledElementDeclarations?.[i]); + } + } + else { + // Copy other element kinds with no change. + addElement(type, flags, target.labeledElementDeclarations?.[i]); + } + } + // Turn optional elements preceding the last required element into required elements + for (let i = 0; i < lastRequiredIndex; i++) { + if (expandedFlags[i] & ElementFlags.Optional) expandedFlags[i] = ElementFlags.Required; + } + if (firstRestIndex >= 0 && firstRestIndex < lastOptionalOrRestIndex) { + // Turn elements between first rest and last optional/rest into a single rest element + expandedTypes[firstRestIndex] = getUnionType(sameMap(expandedTypes.slice(firstRestIndex, lastOptionalOrRestIndex + 1), (t, i) => expandedFlags[firstRestIndex + i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t)); + expandedTypes.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); + expandedFlags.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); + expandedDeclarations.splice(firstRestIndex + 1, lastOptionalOrRestIndex - firstRestIndex); + } + const tupleTarget = getTupleTargetType(expandedFlags, target.readonly, expandedDeclarations); + return tupleTarget === emptyGenericType ? emptyObjectType : + expandedFlags.length ? createTypeReference(tupleTarget, expandedTypes) : + tupleTarget; + + function addElement(type: Type, flags: ElementFlags, declaration: NamedTupleMember | ParameterDeclaration | undefined) { + if (flags & ElementFlags.Required) { + lastRequiredIndex = expandedFlags.length; + } + if (flags & ElementFlags.Rest && firstRestIndex < 0) { + firstRestIndex = expandedFlags.length; + } + if (flags & (ElementFlags.Optional | ElementFlags.Rest)) { + lastOptionalOrRestIndex = expandedFlags.length; + } + expandedTypes.push(flags & ElementFlags.Optional ? addOptionality(type, /*isProperty*/ true) : type); + expandedFlags.push(flags); + expandedDeclarations.push(declaration); + } + } + + function sliceTupleType(type: TupleTypeReference, index: number, endSkipCount = 0) { + const target = type.target; + const endIndex = getTypeReferenceArity(type) - endSkipCount; + return index > target.fixedLength ? getRestArrayTypeOfTupleType(type) || createTupleType(emptyArray) : + createTupleType(getTypeArguments(type).slice(index, endIndex), target.elementFlags.slice(index, endIndex), /*readonly*/ false, target.labeledElementDeclarations && target.labeledElementDeclarations.slice(index, endIndex)); + } + + function getKnownKeysOfTupleType(type: TupleTypeReference) { + return getUnionType(append(arrayOf(type.target.fixedLength, i => getStringLiteralType("" + i)), getIndexType(type.target.readonly ? globalReadonlyArrayType : globalArrayType))); + } + + // Return count of starting consecutive tuple elements of the given kind(s) + function getStartElementCount(type: TupleType, flags: ElementFlags) { + const index = findIndex(type.elementFlags, f => !(f & flags)); + return index >= 0 ? index : type.elementFlags.length; + } + + // Return count of ending consecutive tuple elements of the given kind(s) + function getEndElementCount(type: TupleType, flags: ElementFlags) { + return type.elementFlags.length - findLastIndex(type.elementFlags, f => !(f & flags)) - 1; + } + + function getTotalFixedElementCount(type: TupleType) { + return type.fixedLength + getEndElementCount(type, ElementFlags.Fixed); + } + + function getElementTypes(type: TupleTypeReference): readonly Type[] { + const typeArguments = getTypeArguments(type); + const arity = getTypeReferenceArity(type); + return typeArguments.length === arity ? typeArguments : typeArguments.slice(0, arity); + } + + function getTypeFromOptionalTypeNode(node: OptionalTypeNode): Type { + return addOptionality(getTypeFromTypeNode(node.type), /*isProperty*/ true); + } + + function getTypeId(type: Type): TypeId { + return type.id; + } + + function containsType(types: readonly Type[], type: Type): boolean { + return binarySearch(types, type, getTypeId, compareValues) >= 0; + } + + function insertType(types: Type[], type: Type): boolean { + const index = binarySearch(types, type, getTypeId, compareValues); + if (index < 0) { + types.splice(~index, 0, type); + return true; + } + return false; + } + + function addTypeToUnion(typeSet: Type[], includes: TypeFlags, type: Type) { + const flags = type.flags; + // We ignore 'never' types in unions + if (!(flags & TypeFlags.Never)) { + includes |= flags & TypeFlags.IncludesMask; + if (flags & TypeFlags.Instantiable) includes |= TypeFlags.IncludesInstantiable; + if (flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) includes |= TypeFlags.IncludesConstrainedTypeVariable; + if (type === wildcardType) includes |= TypeFlags.IncludesWildcard; + if (isErrorType(type)) includes |= TypeFlags.IncludesError; + if (!strictNullChecks && flags & TypeFlags.Nullable) { + if (!(getObjectFlags(type) & ObjectFlags.ContainsWideningType)) includes |= TypeFlags.IncludesNonWideningType; + } + else { + const len = typeSet.length; + const index = len && type.id > typeSet[len - 1].id ? ~len : binarySearch(typeSet, type, getTypeId, compareValues); + if (index < 0) { + typeSet.splice(~index, 0, type); + } + } + } + return includes; + } + + // Add the given types to the given type set. Order is preserved, duplicates are removed, + // and nested types of the given kind are flattened into the set. + function addTypesToUnion(typeSet: Type[], includes: TypeFlags, types: readonly Type[]): TypeFlags { + let lastType: Type | undefined; + for (const type of types) { + // We skip the type if it is the same as the last type we processed. This simple test particularly + // saves a lot of work for large lists of the same union type, such as when resolving `Record[A]`, + // where A and B are large union types. + if (type !== lastType) { + includes = type.flags & TypeFlags.Union ? + addTypesToUnion(typeSet, includes | (isNamedUnionType(type) ? TypeFlags.Union : 0), (type as UnionType).types) : + addTypeToUnion(typeSet, includes, type); + lastType = type; + } + } + return includes; + } + + function removeSubtypes(types: Type[], hasObjectTypes: boolean): Type[] | undefined { + // [] and [T] immediately reduce to [] and [T] respectively + if (types.length < 2) { + return types; + } + + const id = getTypeListId(types); + const match = subtypeReductionCache.get(id); + if (match) { + return match; + } + + // We assume that redundant primitive types have already been removed from the types array and that there + // are no any and unknown types in the array. Thus, the only possible supertypes for primitive types are empty + // object types, and if none of those are present we can exclude primitive types from the subtype check. + const hasEmptyObject = hasObjectTypes && some(types, t => !!(t.flags & TypeFlags.Object) && !isGenericMappedType(t) && isEmptyResolvedType(resolveStructuredTypeMembers(t as ObjectType))); + const len = types.length; + let i = len; + let count = 0; + while (i > 0) { + i--; + const source = types[i]; + if (hasEmptyObject || source.flags & TypeFlags.StructuredOrInstantiable) { + // A type parameter with a union constraint may be a subtype of some union, but not a subtype of the + // individual constituents of that union. For example, `T extends A | B` is a subtype of `A | B`, but not + // a subtype of just `A` or just `B`. When we encounter such a type parameter, we therefore check if the + // type parameter is a subtype of a union of all the other types. + if (source.flags & TypeFlags.TypeParameter && getBaseConstraintOrType(source).flags & TypeFlags.Union) { + if (isTypeRelatedTo(source, getUnionType(map(types, t => t === source ? neverType : t)), strictSubtypeRelation)) { + orderedRemoveItemAt(types, i); + } + continue; + } + // Find the first property with a unit type, if any. When constituents have a property by the same name + // but of a different unit type, we can quickly disqualify them from subtype checks. This helps subtype + // reduction of large discriminated union types. + const keyProperty = source.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive) ? + find(getPropertiesOfType(source), p => isUnitType(getTypeOfSymbol(p))) : + undefined; + const keyPropertyType = keyProperty && getRegularTypeOfLiteralType(getTypeOfSymbol(keyProperty)); + for (const target of types) { + if (source !== target) { + if (count === 100000) { + // After 100000 subtype checks we estimate the remaining amount of work by assuming the + // same ratio of checks per element. If the estimated number of remaining type checks is + // greater than 1M we deem the union type too complex to represent. This for example + // caps union types at 1000 unique object types. + const estimatedCount = (count / (len - i)) * len; + if (estimatedCount > 1000000) { + tracing?.instant(tracing.Phase.CheckTypes, "removeSubtypes_DepthLimit", { typeIds: types.map(t => t.id) }); + error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent); + return undefined; + } + } + count++; + if (keyProperty && target.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive)) { + const t = getTypeOfPropertyOfType(target, keyProperty.escapedName); + if (t && isUnitType(t) && getRegularTypeOfLiteralType(t) !== keyPropertyType) { + continue; + } + } + if ( + isTypeRelatedTo(source, target, strictSubtypeRelation) && ( + !(getObjectFlags(getTargetType(source)) & ObjectFlags.Class) || + !(getObjectFlags(getTargetType(target)) & ObjectFlags.Class) || + isTypeDerivedFrom(source, target) + ) + ) { + orderedRemoveItemAt(types, i); + break; + } + } + } + } + } + subtypeReductionCache.set(id, types); + return types; + } + + function removeRedundantLiteralTypes(types: Type[], includes: TypeFlags, reduceVoidUndefined: boolean) { + let i = types.length; + while (i > 0) { + i--; + const t = types[i]; + const flags = t.flags; + const remove = flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && includes & TypeFlags.String || + flags & TypeFlags.NumberLiteral && includes & TypeFlags.Number || + flags & TypeFlags.BigIntLiteral && includes & TypeFlags.BigInt || + flags & TypeFlags.UniqueESSymbol && includes & TypeFlags.ESSymbol || + reduceVoidUndefined && flags & TypeFlags.Undefined && includes & TypeFlags.Void || + isFreshLiteralType(t) && containsType(types, (t as LiteralType).regularType); + if (remove) { + orderedRemoveItemAt(types, i); + } + } + } + + function removeStringLiteralsMatchedByTemplateLiterals(types: Type[]) { + const templates = filter(types, isPatternLiteralType) as (TemplateLiteralType | StringMappingType)[]; + if (templates.length) { + let i = types.length; + while (i > 0) { + i--; + const t = types[i]; + if (t.flags & TypeFlags.StringLiteral && some(templates, template => isTypeMatchedByTemplateLiteralOrStringMapping(t, template))) { + orderedRemoveItemAt(types, i); + } + } + } + } + + function isTypeMatchedByTemplateLiteralOrStringMapping(type: Type, template: TemplateLiteralType | StringMappingType) { + return template.flags & TypeFlags.TemplateLiteral ? + isTypeMatchedByTemplateLiteralType(type, template as TemplateLiteralType) : + isMemberOfStringMapping(type, template); + } + + function removeConstrainedTypeVariables(types: Type[]) { + const typeVariables: TypeVariable[] = []; + // First collect a list of the type variables occurring in constraining intersections. + for (const type of types) { + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) { + const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1; + pushIfUnique(typeVariables, (type as IntersectionType).types[index]); + } + } + // For each type variable, check if the constraining intersections for that type variable fully + // cover the constraint of the type variable; if so, remove the constraining intersections and + // substitute the type variable. + for (const typeVariable of typeVariables) { + const primitives: Type[] = []; + // First collect the primitive types from the constraining intersections. + for (const type of types) { + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) { + const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1; + if ((type as IntersectionType).types[index] === typeVariable) { + insertType(primitives, (type as IntersectionType).types[1 - index]); + } + } + } + // If every constituent in the type variable's constraint is covered by an intersection of the type + // variable and that constituent, remove those intersections and substitute the type variable. + const constraint = getBaseConstraintOfType(typeVariable)!; + if (everyType(constraint, t => containsType(primitives, t))) { + let i = types.length; + while (i > 0) { + i--; + const type = types[i]; + if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) { + const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1; + if ((type as IntersectionType).types[index] === typeVariable && containsType(primitives, (type as IntersectionType).types[1 - index])) { + orderedRemoveItemAt(types, i); + } + } + } + insertType(types, typeVariable); + } + } + } + + function isNamedUnionType(type: Type) { + return !!(type.flags & TypeFlags.Union && (type.aliasSymbol || (type as UnionType).origin)); + } + + function addNamedUnions(namedUnions: Type[], types: readonly Type[]) { + for (const t of types) { + if (t.flags & TypeFlags.Union) { + const origin = (t as UnionType).origin; + if (t.aliasSymbol || origin && !(origin.flags & TypeFlags.Union)) { + pushIfUnique(namedUnions, t); + } + else if (origin && origin.flags & TypeFlags.Union) { + addNamedUnions(namedUnions, (origin as UnionType).types); + } + } + } + } + + function createOriginUnionOrIntersectionType(flags: TypeFlags, types: Type[]) { + const result = createOriginType(flags) as UnionOrIntersectionType; + result.types = types; + return result; + } + + // We sort and deduplicate the constituent types based on object identity. If the subtypeReduction + // flag is specified we also reduce the constituent type set to only include types that aren't subtypes + // of other types. Subtype reduction is expensive for large union types and is possible only when union + // types are known not to circularly reference themselves (as is the case with union types created by + // expression constructs such as array literals and the || and ?: operators). Named types can + // circularly reference themselves and therefore cannot be subtype reduced during their declaration. + // For example, "type Item = string | (() => Item" is a named type that circularly references itself. + function getUnionType(types: readonly Type[], unionReduction: UnionReduction = UnionReduction.Literal, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[], origin?: Type): Type { + if (types.length === 0) { + return neverType; + } + if (types.length === 1) { + return types[0]; + } + // We optimize for the common case of unioning a union type with some other type (such as `undefined`). + if (types.length === 2 && !origin && (types[0].flags & TypeFlags.Union || types[1].flags & TypeFlags.Union)) { + const infix = unionReduction === UnionReduction.None ? "N" : unionReduction === UnionReduction.Subtype ? "S" : "L"; + const index = types[0].id < types[1].id ? 0 : 1; + const id = types[index].id + infix + types[1 - index].id + getAliasId(aliasSymbol, aliasTypeArguments); + let type = unionOfUnionTypes.get(id); + if (!type) { + type = getUnionTypeWorker(types, unionReduction, aliasSymbol, aliasTypeArguments, /*origin*/ undefined); + unionOfUnionTypes.set(id, type); + } + return type; + } + return getUnionTypeWorker(types, unionReduction, aliasSymbol, aliasTypeArguments, origin); + } + + function getUnionTypeWorker(types: readonly Type[], unionReduction: UnionReduction, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined, origin: Type | undefined): Type { + let typeSet: Type[] | undefined = []; + const includes = addTypesToUnion(typeSet, 0 as TypeFlags, types); + if (unionReduction !== UnionReduction.None) { + if (includes & TypeFlags.AnyOrUnknown) { + return includes & TypeFlags.Any ? + includes & TypeFlags.IncludesWildcard ? wildcardType : + includes & TypeFlags.IncludesError ? errorType : anyType : + unknownType; + } + if (includes & TypeFlags.Undefined) { + // If type set contains both undefinedType and missingType, remove missingType + if (typeSet.length >= 2 && typeSet[0] === undefinedType && typeSet[1] === missingType) { + orderedRemoveItemAt(typeSet, 1); + } + } + if (includes & (TypeFlags.Enum | TypeFlags.Literal | TypeFlags.UniqueESSymbol | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || includes & TypeFlags.Void && includes & TypeFlags.Undefined) { + removeRedundantLiteralTypes(typeSet, includes, !!(unionReduction & UnionReduction.Subtype)); + } + if (includes & TypeFlags.StringLiteral && includes & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping)) { + removeStringLiteralsMatchedByTemplateLiterals(typeSet); + } + if (includes & TypeFlags.IncludesConstrainedTypeVariable) { + removeConstrainedTypeVariables(typeSet); + } + if (unionReduction === UnionReduction.Subtype) { + typeSet = removeSubtypes(typeSet, !!(includes & TypeFlags.Object)); + if (!typeSet) { + return errorType; + } + } + if (typeSet.length === 0) { + return includes & TypeFlags.Null ? includes & TypeFlags.IncludesNonWideningType ? nullType : nullWideningType : + includes & TypeFlags.Undefined ? includes & TypeFlags.IncludesNonWideningType ? undefinedType : undefinedWideningType : + neverType; + } + } + if (!origin && includes & TypeFlags.Union) { + const namedUnions: Type[] = []; + addNamedUnions(namedUnions, types); + const reducedTypes: Type[] = []; + for (const t of typeSet) { + if (!some(namedUnions, union => containsType((union as UnionType).types, t))) { + reducedTypes.push(t); + } + } + if (!aliasSymbol && namedUnions.length === 1 && reducedTypes.length === 0) { + return namedUnions[0]; + } + // We create a denormalized origin type only when the union was created from one or more named unions + // (unions with alias symbols or origins) and when there is no overlap between those named unions. + const namedTypesCount = reduceLeft(namedUnions, (sum, union) => sum + (union as UnionType).types.length, 0); + if (namedTypesCount + reducedTypes.length === typeSet.length) { + for (const t of namedUnions) { + insertType(reducedTypes, t); + } + origin = createOriginUnionOrIntersectionType(TypeFlags.Union, reducedTypes); + } + } + const objectFlags = (includes & TypeFlags.NotPrimitiveUnion ? 0 : ObjectFlags.PrimitiveUnion) | + (includes & TypeFlags.Intersection ? ObjectFlags.ContainsIntersections : 0); + return getUnionTypeFromSortedList(typeSet, objectFlags, aliasSymbol, aliasTypeArguments, origin); + } + + function getUnionOrIntersectionTypePredicate(signatures: readonly Signature[], kind: TypeFlags | undefined): TypePredicate | undefined { + let last: TypePredicate | undefined; + const types: Type[] = []; + for (const sig of signatures) { + const pred = getTypePredicateOfSignature(sig); + if (pred) { + // Constituent type predicates must all have matching kinds. We don't create composite type predicates for assertions. + if (pred.kind !== TypePredicateKind.This && pred.kind !== TypePredicateKind.Identifier || last && !typePredicateKindsMatch(last, pred)) { + return undefined; + } + last = pred; + types.push(pred.type); + } + else { + // In composite union signatures we permit and ignore signatures with a return type `false`. + const returnType = kind !== TypeFlags.Intersection ? getReturnTypeOfSignature(sig) : undefined; + if (returnType !== falseType && returnType !== regularFalseType) { + return undefined; + } + } + } + if (!last) { + return undefined; + } + const compositeType = getUnionOrIntersectionType(types, kind); + return createTypePredicate(last.kind, last.parameterName, last.parameterIndex, compositeType); + } + + function typePredicateKindsMatch(a: TypePredicate, b: TypePredicate): boolean { + return a.kind === b.kind && a.parameterIndex === b.parameterIndex; + } + + // This function assumes the constituent type list is sorted and deduplicated. + function getUnionTypeFromSortedList(types: Type[], precomputedObjectFlags: ObjectFlags, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[], origin?: Type): Type { + if (types.length === 0) { + return neverType; + } + if (types.length === 1) { + return types[0]; + } + const typeKey = !origin ? getTypeListId(types) : + origin.flags & TypeFlags.Union ? `|${getTypeListId((origin as UnionType).types)}` : + origin.flags & TypeFlags.Intersection ? `&${getTypeListId((origin as IntersectionType).types)}` : + `#${(origin as IndexType).type.id}|${getTypeListId(types)}`; // origin type id alone is insufficient, as `keyof x` may resolve to multiple WIP values while `x` is still resolving + const id = typeKey + getAliasId(aliasSymbol, aliasTypeArguments); + let type = unionTypes.get(id); + if (!type) { + type = createType(TypeFlags.Union) as UnionType; + type.objectFlags = precomputedObjectFlags | getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable); + type.types = types; + type.origin = origin; + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = aliasTypeArguments; + if (types.length === 2 && types[0].flags & TypeFlags.BooleanLiteral && types[1].flags & TypeFlags.BooleanLiteral) { + type.flags |= TypeFlags.Boolean; + (type as UnionType & IntrinsicType).intrinsicName = "boolean"; + } + unionTypes.set(id, type); + } + return type; + } + + function getTypeFromUnionTypeNode(node: UnionTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const aliasSymbol = getAliasSymbolForTypeNode(node); + links.resolvedType = getUnionType(map(node.types, getTypeFromTypeNode), UnionReduction.Literal, aliasSymbol, getTypeArgumentsForAliasSymbol(aliasSymbol)); + } + return links.resolvedType; + } + + function addTypeToIntersection(typeSet: Map, includes: TypeFlags, type: Type) { + const flags = type.flags; + if (flags & TypeFlags.Intersection) { + return addTypesToIntersection(typeSet, includes, (type as IntersectionType).types); + } + if (isEmptyAnonymousObjectType(type)) { + if (!(includes & TypeFlags.IncludesEmptyObject)) { + includes |= TypeFlags.IncludesEmptyObject; + typeSet.set(type.id.toString(), type); + } + } + else { + if (flags & TypeFlags.AnyOrUnknown) { + if (type === wildcardType) includes |= TypeFlags.IncludesWildcard; + if (isErrorType(type)) includes |= TypeFlags.IncludesError; + } + else if (strictNullChecks || !(flags & TypeFlags.Nullable)) { + if (type === missingType) { + includes |= TypeFlags.IncludesMissingType; + type = undefinedType; + } + if (!typeSet.has(type.id.toString())) { + if (type.flags & TypeFlags.Unit && includes & TypeFlags.Unit) { + // We have seen two distinct unit types which means we should reduce to an + // empty intersection. Adding TypeFlags.NonPrimitive causes that to happen. + includes |= TypeFlags.NonPrimitive; + } + typeSet.set(type.id.toString(), type); + } + } + includes |= flags & TypeFlags.IncludesMask; + } + return includes; + } + + // Add the given types to the given type set. Order is preserved, freshness is removed from literal + // types, duplicates are removed, and nested types of the given kind are flattened into the set. + function addTypesToIntersection(typeSet: Map, includes: TypeFlags, types: readonly Type[]) { + for (const type of types) { + includes = addTypeToIntersection(typeSet, includes, getRegularTypeOfLiteralType(type)); + } + return includes; + } + + function removeRedundantSupertypes(types: Type[], includes: TypeFlags) { + let i = types.length; + while (i > 0) { + i--; + const t = types[i]; + const remove = t.flags & TypeFlags.String && includes & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || + t.flags & TypeFlags.Number && includes & TypeFlags.NumberLiteral || + t.flags & TypeFlags.BigInt && includes & TypeFlags.BigIntLiteral || + t.flags & TypeFlags.ESSymbol && includes & TypeFlags.UniqueESSymbol || + t.flags & TypeFlags.Void && includes & TypeFlags.Undefined || + isEmptyAnonymousObjectType(t) && includes & TypeFlags.DefinitelyNonNullable; + if (remove) { + orderedRemoveItemAt(types, i); + } + } + } + + // Check that the given type has a match in every union. A given type is matched by + // an identical type, and a literal type is additionally matched by its corresponding + // primitive type. + function eachUnionContains(unionTypes: UnionType[], type: Type) { + for (const u of unionTypes) { + if (!containsType(u.types, type)) { + const primitive = type.flags & TypeFlags.StringLiteral ? stringType : + type.flags & (TypeFlags.Enum | TypeFlags.NumberLiteral) ? numberType : + type.flags & TypeFlags.BigIntLiteral ? bigintType : + type.flags & TypeFlags.UniqueESSymbol ? esSymbolType : + undefined; + if (!primitive || !containsType(u.types, primitive)) { + return false; + } + } + } + return true; + } + + /** + * Returns true if the intersection of the template literals and string literals is the empty set, + * for example `get${string}` & "setX", and should reduce to never. + */ + function extractRedundantTemplateLiterals(types: Type[]): boolean { + let i = types.length; + const literals = filter(types, t => !!(t.flags & TypeFlags.StringLiteral)); + while (i > 0) { + i--; + const t = types[i]; + if (!(t.flags & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping))) continue; + for (const t2 of literals) { + if (isTypeSubtypeOf(t2, t)) { + // For example, `get${T}` & "getX" is just "getX", and Lowercase & "foo" is just "foo" + orderedRemoveItemAt(types, i); + break; + } + else if (isPatternLiteralType(t)) { + return true; + } + } + } + return false; + } + + function removeFromEach(types: Type[], flag: TypeFlags) { + for (let i = 0; i < types.length; i++) { + types[i] = filterType(types[i], t => !(t.flags & flag)); + } + } + + // If the given list of types contains more than one union of primitive types, replace the + // first with a union containing an intersection of those primitive types, then remove the + // other unions and return true. Otherwise, do nothing and return false. + function intersectUnionsOfPrimitiveTypes(types: Type[]) { + let unionTypes: UnionType[] | undefined; + const index = findIndex(types, t => !!(getObjectFlags(t) & ObjectFlags.PrimitiveUnion)); + if (index < 0) { + return false; + } + let i = index + 1; + // Remove all but the first union of primitive types and collect them in + // the unionTypes array. + while (i < types.length) { + const t = types[i]; + if (getObjectFlags(t) & ObjectFlags.PrimitiveUnion) { + (unionTypes || (unionTypes = [types[index] as UnionType])).push(t as UnionType); + orderedRemoveItemAt(types, i); + } + else { + i++; + } + } + // Return false if there was only one union of primitive types + if (!unionTypes) { + return false; + } + // We have more than one union of primitive types, now intersect them. For each + // type in each union we check if the type is matched in every union and if so + // we include it in the result. + const checked: Type[] = []; + const result: Type[] = []; + for (const u of unionTypes) { + for (const t of u.types) { + if (insertType(checked, t)) { + if (eachUnionContains(unionTypes, t)) { + insertType(result, t); + } + } + } + } + // Finally replace the first union with the result + types[index] = getUnionTypeFromSortedList(result, ObjectFlags.PrimitiveUnion); + return true; + } + + function createIntersectionType(types: Type[], objectFlags: ObjectFlags, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]) { + const result = createType(TypeFlags.Intersection) as IntersectionType; + result.objectFlags = objectFlags | getPropagatingFlagsOfTypes(types, /*excludeKinds*/ TypeFlags.Nullable); + result.types = types; + result.aliasSymbol = aliasSymbol; + result.aliasTypeArguments = aliasTypeArguments; + return result; + } + + // We normalize combinations of intersection and union types based on the distributive property of the '&' + // operator. Specifically, because X & (A | B) is equivalent to X & A | X & B, we can transform intersection + // types with union type constituents into equivalent union types with intersection type constituents and + // effectively ensure that union types are always at the top level in type representations. + // + // We do not perform structural deduplication on intersection types. Intersection types are created only by the & + // type operator and we can't reduce those because we want to support recursive intersection types. For example, + // a type alias of the form "type List = T & { next: List }" cannot be reduced during its declaration. + // Also, unlike union types, the order of the constituent types is preserved in order that overload resolution + // for intersections of types with signatures can be deterministic. + function getIntersectionType(types: readonly Type[], flags = IntersectionFlags.None, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + const typeMembershipMap = new Map(); + const includes = addTypesToIntersection(typeMembershipMap, 0 as TypeFlags, types); + const typeSet: Type[] = arrayFrom(typeMembershipMap.values()); + let objectFlags = ObjectFlags.None; + // An intersection type is considered empty if it contains + // the type never, or + // more than one unit type or, + // an object type and a nullable type (null or undefined), or + // a string-like type and a type known to be non-string-like, or + // a number-like type and a type known to be non-number-like, or + // a symbol-like type and a type known to be non-symbol-like, or + // a void-like type and a type known to be non-void-like, or + // a non-primitive type and a type known to be primitive. + if (includes & TypeFlags.Never) { + return contains(typeSet, silentNeverType) ? silentNeverType : neverType; + } + if ( + strictNullChecks && includes & TypeFlags.Nullable && includes & (TypeFlags.Object | TypeFlags.NonPrimitive | TypeFlags.IncludesEmptyObject) || + includes & TypeFlags.NonPrimitive && includes & (TypeFlags.DisjointDomains & ~TypeFlags.NonPrimitive) || + includes & TypeFlags.StringLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.StringLike) || + includes & TypeFlags.NumberLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.NumberLike) || + includes & TypeFlags.BigIntLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.BigIntLike) || + includes & TypeFlags.ESSymbolLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.ESSymbolLike) || + includes & TypeFlags.VoidLike && includes & (TypeFlags.DisjointDomains & ~TypeFlags.VoidLike) + ) { + return neverType; + } + if (includes & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && includes & TypeFlags.StringLiteral && extractRedundantTemplateLiterals(typeSet)) { + return neverType; + } + if (includes & TypeFlags.Any) { + return includes & TypeFlags.IncludesWildcard ? wildcardType : includes & TypeFlags.IncludesError ? errorType : anyType; + } + if (!strictNullChecks && includes & TypeFlags.Nullable) { + return includes & TypeFlags.IncludesEmptyObject ? neverType : includes & TypeFlags.Undefined ? undefinedType : nullType; + } + if ( + includes & TypeFlags.String && includes & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) || + includes & TypeFlags.Number && includes & TypeFlags.NumberLiteral || + includes & TypeFlags.BigInt && includes & TypeFlags.BigIntLiteral || + includes & TypeFlags.ESSymbol && includes & TypeFlags.UniqueESSymbol || + includes & TypeFlags.Void && includes & TypeFlags.Undefined || + includes & TypeFlags.IncludesEmptyObject && includes & TypeFlags.DefinitelyNonNullable + ) { + if (!(flags & IntersectionFlags.NoSupertypeReduction)) removeRedundantSupertypes(typeSet, includes); + } + if (includes & TypeFlags.IncludesMissingType) { + typeSet[typeSet.indexOf(undefinedType)] = missingType; + } + if (typeSet.length === 0) { + return unknownType; + } + if (typeSet.length === 1) { + return typeSet[0]; + } + if (typeSet.length === 2 && !(flags & IntersectionFlags.NoConstraintReduction)) { + const typeVarIndex = typeSet[0].flags & TypeFlags.TypeVariable ? 0 : 1; + const typeVariable = typeSet[typeVarIndex]; + const primitiveType = typeSet[1 - typeVarIndex]; + if ( + typeVariable.flags & TypeFlags.TypeVariable && + (primitiveType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive) && !isGenericStringLikeType(primitiveType) || includes & TypeFlags.IncludesEmptyObject) + ) { + // We have an intersection T & P or P & T, where T is a type variable and P is a primitive type, the object type, or {}. + const constraint = getBaseConstraintOfType(typeVariable); + // Check that T's constraint is similarly composed of primitive types, the object type, or {}. + if (constraint && everyType(constraint, t => !!(t.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive)) || isEmptyAnonymousObjectType(t))) { + // If T's constraint is a subtype of P, simply return T. For example, given `T extends "a" | "b"`, + // the intersection `T & string` reduces to just T. + if (isTypeStrictSubtypeOf(constraint, primitiveType)) { + return typeVariable; + } + if (!(constraint.flags & TypeFlags.Union && someType(constraint, c => isTypeStrictSubtypeOf(c, primitiveType)))) { + // No constituent of T's constraint is a subtype of P. If P is also not a subtype of T's constraint, + // then the constraint and P are unrelated, and the intersection reduces to never. For example, given + // `T extends "a" | "b"`, the intersection `T & number` reduces to never. + if (!isTypeStrictSubtypeOf(primitiveType, constraint)) { + return neverType; + } + } + // Some constituent of T's constraint is a subtype of P, or P is a subtype of T's constraint. Thus, + // the intersection further constrains the type variable. For example, given `T extends string | number`, + // the intersection `T & "a"` is marked as a constrained type variable. Likewise, given `T extends "a" | 1`, + // the intersection `T & number` is marked as a constrained type variable. + objectFlags = ObjectFlags.IsConstrainedTypeVariable; + } + } + } + const id = getTypeListId(typeSet) + (flags & IntersectionFlags.NoConstraintReduction ? "*" : getAliasId(aliasSymbol, aliasTypeArguments)); + let result = intersectionTypes.get(id); + if (!result) { + if (includes & TypeFlags.Union) { + if (intersectUnionsOfPrimitiveTypes(typeSet)) { + // When the intersection creates a reduced set (which might mean that *all* union types have + // disappeared), we restart the operation to get a new set of combined flags. Once we have + // reduced we'll never reduce again, so this occurs at most once. + result = getIntersectionType(typeSet, flags, aliasSymbol, aliasTypeArguments); + } + else if (every(typeSet, t => !!(t.flags & TypeFlags.Union && (t as UnionType).types[0].flags & TypeFlags.Undefined))) { + const containedUndefinedType = some(typeSet, containsMissingType) ? missingType : undefinedType; + removeFromEach(typeSet, TypeFlags.Undefined); + result = getUnionType([getIntersectionType(typeSet, flags), containedUndefinedType], UnionReduction.Literal, aliasSymbol, aliasTypeArguments); + } + else if (every(typeSet, t => !!(t.flags & TypeFlags.Union && ((t as UnionType).types[0].flags & TypeFlags.Null || (t as UnionType).types[1].flags & TypeFlags.Null)))) { + removeFromEach(typeSet, TypeFlags.Null); + result = getUnionType([getIntersectionType(typeSet, flags), nullType], UnionReduction.Literal, aliasSymbol, aliasTypeArguments); + } + else if (typeSet.length >= 4) { + // When we have four or more constituents, some of which are unions, we employ a "divide and conquer" strategy + // where A & B & C & D is processed as (A & B) & (C & D). Since intersections of unions often produce far smaller + // unions of intersections than the full cartesian product (due to some intersections becoming `never`), this can + // dramatically reduce the overall work. + const middle = Math.floor(typeSet.length / 2); + result = getIntersectionType([getIntersectionType(typeSet.slice(0, middle), flags), getIntersectionType(typeSet.slice(middle), flags)], flags, aliasSymbol, aliasTypeArguments); + } + else { + // We are attempting to construct a type of the form X & (A | B) & (C | D). Transform this into a type of + // the form X & A & C | X & A & D | X & B & C | X & B & D. If the estimated size of the resulting union type + // exceeds 100000 constituents, report an error. + if (!checkCrossProductUnion(typeSet)) { + return errorType; + } + const constituents = getCrossProductIntersections(typeSet, flags); + // We attach a denormalized origin type when at least one constituent of the cross-product union is an + // intersection (i.e. when the intersection didn't just reduce one or more unions to smaller unions) and + // the denormalized origin has fewer constituents than the union itself. + const origin = some(constituents, t => !!(t.flags & TypeFlags.Intersection)) && getConstituentCountOfTypes(constituents) > getConstituentCountOfTypes(typeSet) ? createOriginUnionOrIntersectionType(TypeFlags.Intersection, typeSet) : undefined; + result = getUnionType(constituents, UnionReduction.Literal, aliasSymbol, aliasTypeArguments, origin); + } + } + else { + result = createIntersectionType(typeSet, objectFlags, aliasSymbol, aliasTypeArguments); + } + intersectionTypes.set(id, result); + } + return result; + } + + function getCrossProductUnionSize(types: readonly Type[]) { + return reduceLeft(types, (n, t) => t.flags & TypeFlags.Union ? n * (t as UnionType).types.length : t.flags & TypeFlags.Never ? 0 : n, 1); + } + + function checkCrossProductUnion(types: readonly Type[]) { + const size = getCrossProductUnionSize(types); + if (size >= 100000) { + tracing?.instant(tracing.Phase.CheckTypes, "checkCrossProductUnion_DepthLimit", { typeIds: types.map(t => t.id), size }); + error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent); + return false; + } + return true; + } + + function getCrossProductIntersections(types: readonly Type[], flags: IntersectionFlags) { + const count = getCrossProductUnionSize(types); + const intersections: Type[] = []; + for (let i = 0; i < count; i++) { + const constituents = types.slice(); + let n = i; + for (let j = types.length - 1; j >= 0; j--) { + if (types[j].flags & TypeFlags.Union) { + const sourceTypes = (types[j] as UnionType).types; + const length = sourceTypes.length; + constituents[j] = sourceTypes[n % length]; + n = Math.floor(n / length); + } + } + const t = getIntersectionType(constituents, flags); + if (!(t.flags & TypeFlags.Never)) intersections.push(t); + } + return intersections; + } + + function getConstituentCount(type: Type): number { + return !(type.flags & TypeFlags.UnionOrIntersection) || type.aliasSymbol ? 1 : + type.flags & TypeFlags.Union && (type as UnionType).origin ? getConstituentCount((type as UnionType).origin!) : + getConstituentCountOfTypes((type as UnionOrIntersectionType).types); + } + + function getConstituentCountOfTypes(types: Type[]): number { + return reduceLeft(types, (n, t) => n + getConstituentCount(t), 0); + } + + function getTypeFromIntersectionTypeNode(node: IntersectionTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const aliasSymbol = getAliasSymbolForTypeNode(node); + const types = map(node.types, getTypeFromTypeNode); + // We perform no supertype reduction for X & {} or {} & X, where X is one of string, number, bigint, + // or a pattern literal template type. This enables union types like "a" | "b" | string & {} or + // "aa" | "ab" | `a${string}` which preserve the literal types for purposes of statement completion. + const emptyIndex = types.length === 2 ? types.indexOf(emptyTypeLiteralType) : -1; + const t = emptyIndex >= 0 ? types[1 - emptyIndex] : unknownType; + const noSupertypeReduction = !!(t.flags & (TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt) || t.flags & TypeFlags.TemplateLiteral && isPatternLiteralType(t)); + links.resolvedType = getIntersectionType(types, noSupertypeReduction ? IntersectionFlags.NoSupertypeReduction : 0, aliasSymbol, getTypeArgumentsForAliasSymbol(aliasSymbol)); + } + return links.resolvedType; + } + + function createIndexType(type: InstantiableType | UnionOrIntersectionType, indexFlags: IndexFlags) { + const result = createType(TypeFlags.Index) as IndexType; + result.type = type; + result.indexFlags = indexFlags; + return result; + } + + function createOriginIndexType(type: InstantiableType | UnionOrIntersectionType) { + const result = createOriginType(TypeFlags.Index) as IndexType; + result.type = type; + return result; + } + + function getIndexTypeForGenericType(type: InstantiableType | UnionOrIntersectionType, indexFlags: IndexFlags) { + return indexFlags & IndexFlags.StringsOnly ? + type.resolvedStringIndexType || (type.resolvedStringIndexType = createIndexType(type, IndexFlags.StringsOnly)) : + type.resolvedIndexType || (type.resolvedIndexType = createIndexType(type, IndexFlags.None)); + } + + /** + * This roughly mirrors `resolveMappedTypeMembers` in the nongeneric case, except only reports a union of the keys calculated, + * rather than manufacturing the properties. We can't just fetch the `constraintType` since that would ignore mappings + * and mapping the `constraintType` directly ignores how mapped types map _properties_ and not keys (thus ignoring subtype + * reduction in the constraintType) when possible. + * @param noIndexSignatures Indicates if _string_ index signatures should be elided. (other index signatures are always reported) + */ + function getIndexTypeForMappedType(type: MappedType, indexFlags: IndexFlags) { + const typeParameter = getTypeParameterFromMappedType(type); + const constraintType = getConstraintTypeFromMappedType(type); + const nameType = getNameTypeFromMappedType(type.target as MappedType || type); + if (!nameType && !(indexFlags & IndexFlags.NoIndexSignatures)) { + // no mapping and no filtering required, just quickly bail to returning the constraint in the common case + return constraintType; + } + const keyTypes: Type[] = []; + // Calling getApparentType on the `T` of a `keyof T` in the constraint type of a generic mapped type can + // trigger a circularity. For example, `T extends { [P in keyof T & string as Captitalize

]: any }` is + // a circular definition. For this reason, we only eagerly manifest the keys if the constraint is non-generic. + if (isGenericIndexType(constraintType)) { + if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + // We have a generic index and a homomorphic mapping (but a distributive key remapping) - we need to defer + // the whole `keyof whatever` for later since it's not safe to resolve the shape of modifier type. + return getIndexTypeForGenericType(type, indexFlags); + } + // Include the generic component in the resulting type. + forEachType(constraintType, addMemberForKeyType); + } + else if (isMappedTypeWithKeyofConstraintDeclaration(type)) { + const modifiersType = getApparentType(getModifiersTypeFromMappedType(type)); // The 'T' in 'keyof T' + forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType(modifiersType, TypeFlags.StringOrNumberLiteralOrUnique, !!(indexFlags & IndexFlags.StringsOnly), addMemberForKeyType); + } + else { + forEachType(getLowerBoundOfKeyType(constraintType), addMemberForKeyType); + } + // We had to pick apart the constraintType to potentially map/filter it - compare the final resulting list with the + // original constraintType, so we can return the union that preserves aliases/origin data if possible. + const result = indexFlags & IndexFlags.NoIndexSignatures ? filterType(getUnionType(keyTypes), t => !(t.flags & (TypeFlags.Any | TypeFlags.String))) : getUnionType(keyTypes); + if (result.flags & TypeFlags.Union && constraintType.flags & TypeFlags.Union && getTypeListId((result as UnionType).types) === getTypeListId((constraintType as UnionType).types)) { + return constraintType; + } + return result; + + function addMemberForKeyType(keyType: Type) { + const propNameType = nameType ? instantiateType(nameType, appendTypeMapping(type.mapper, typeParameter, keyType)) : keyType; + // `keyof` currently always returns `string | number` for concrete `string` index signatures - the below ternary keeps that behavior for mapped types + // See `getLiteralTypeFromProperties` where there's a similar ternary to cause the same behavior. + keyTypes.push(propNameType === stringType ? stringOrNumberType : propNameType); + } + } + + // Ordinarily we reduce a keyof M, where M is a mapped type { [P in K as N

) + const { expression } = node as JsxExpression; + return !!expression && isContextSensitive(expression); + } + } + + return false; + } + + function isContextSensitiveFunctionLikeDeclaration(node: FunctionLikeDeclaration): boolean { + return hasContextSensitiveParameters(node) || hasContextSensitiveReturnExpression(node); + } + + function hasContextSensitiveReturnExpression(node: FunctionLikeDeclaration) { + if (node.typeParameters || getEffectiveReturnTypeNode(node) || !node.body) { + return false; + } + if (node.body.kind !== SyntaxKind.Block) { + return isContextSensitive(node.body); + } + return !!forEachReturnStatement(node.body as Block, statement => !!statement.expression && isContextSensitive(statement.expression)); + } + + function isContextSensitiveFunctionOrObjectLiteralMethod(func: Node): func is FunctionExpression | ArrowFunction | MethodDeclaration { + return (isFunctionExpressionOrArrowFunction(func) || isObjectLiteralMethod(func)) && + isContextSensitiveFunctionLikeDeclaration(func); + } + + function getTypeWithoutSignatures(type: Type): Type { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + if (resolved.constructSignatures.length || resolved.callSignatures.length) { + const result = createObjectType(ObjectFlags.Anonymous, type.symbol); + result.members = resolved.members; + result.properties = resolved.properties; + result.callSignatures = emptyArray; + result.constructSignatures = emptyArray; + result.indexInfos = emptyArray; + return result; + } + } + else if (type.flags & TypeFlags.Intersection) { + return getIntersectionType(map((type as IntersectionType).types, getTypeWithoutSignatures)); + } + return type; + } + + // TYPE CHECKING + + function isTypeIdenticalTo(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, identityRelation); + } + + function compareTypesIdentical(source: Type, target: Type): Ternary { + return isTypeRelatedTo(source, target, identityRelation) ? Ternary.True : Ternary.False; + } + + function compareTypesAssignable(source: Type, target: Type): Ternary { + return isTypeRelatedTo(source, target, assignableRelation) ? Ternary.True : Ternary.False; + } + + function compareTypesSubtypeOf(source: Type, target: Type): Ternary { + return isTypeRelatedTo(source, target, subtypeRelation) ? Ternary.True : Ternary.False; + } + + function isTypeSubtypeOf(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, subtypeRelation); + } + + function isTypeStrictSubtypeOf(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, strictSubtypeRelation); + } + + function isTypeAssignableTo(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, assignableRelation); + } + + // An object type S is considered to be derived from an object type T if + // S is a union type and every constituent of S is derived from T, + // T is a union type and S is derived from at least one constituent of T, or + // S is an intersection type and some constituent of S is derived from T, or + // S is a type variable with a base constraint that is derived from T, or + // T is {} and S is an object-like type (ensuring {} is less derived than Object), or + // T is one of the global types Object and Function and S is a subtype of T, or + // T occurs directly or indirectly in an 'extends' clause of S. + // Note that this check ignores type parameters and only considers the + // inheritance hierarchy. + function isTypeDerivedFrom(source: Type, target: Type): boolean { + return source.flags & TypeFlags.Union ? every((source as UnionType).types, t => isTypeDerivedFrom(t, target)) : + target.flags & TypeFlags.Union ? some((target as UnionType).types, t => isTypeDerivedFrom(source, t)) : + source.flags & TypeFlags.Intersection ? some((source as IntersectionType).types, t => isTypeDerivedFrom(t, target)) : + source.flags & TypeFlags.InstantiableNonPrimitive ? isTypeDerivedFrom(getBaseConstraintOfType(source) || unknownType, target) : + isEmptyAnonymousObjectType(target) ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) : + target === globalObjectType ? !!(source.flags & (TypeFlags.Object | TypeFlags.NonPrimitive)) && !isEmptyAnonymousObjectType(source) : + target === globalFunctionType ? !!(source.flags & TypeFlags.Object) && isFunctionObjectType(source as ObjectType) : + hasBaseType(source, getTargetType(target)) || (isArrayType(target) && !isReadonlyArrayType(target) && isTypeDerivedFrom(source, globalReadonlyArrayType)); + } + + /** + * This is *not* a bi-directional relationship. + * If one needs to check both directions for comparability, use a second call to this function or 'checkTypeComparableTo'. + * + * A type S is comparable to a type T if some (but not necessarily all) of the possible values of S are also possible values of T. + * It is used to check following cases: + * - the types of the left and right sides of equality/inequality operators (`===`, `!==`, `==`, `!=`). + * - the types of `case` clause expressions and their respective `switch` expressions. + * - the type of an expression in a type assertion with the type being asserted. + */ + function isTypeComparableTo(source: Type, target: Type): boolean { + return isTypeRelatedTo(source, target, comparableRelation); + } + + function areTypesComparable(type1: Type, type2: Type): boolean { + return isTypeComparableTo(type1, type2) || isTypeComparableTo(type2, type1); + } + + function checkTypeAssignableTo(source: Type, target: Type, errorNode: Node | undefined, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined, errorOutputObject?: { errors?: Diagnostic[]; }): boolean { + return checkTypeRelatedTo(source, target, assignableRelation, errorNode, headMessage, containingMessageChain, errorOutputObject); + } + + /** + * Like `checkTypeAssignableTo`, but if it would issue an error, instead performs structural comparisons of the types using the given expression node to + * attempt to issue more specific errors on, for example, specific object literal properties or tuple members. + */ + function checkTypeAssignableToAndOptionallyElaborate(source: Type, target: Type, errorNode: Node | undefined, expr: Expression | undefined, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined): boolean { + return checkTypeRelatedToAndOptionallyElaborate(source, target, assignableRelation, errorNode, expr, headMessage, containingMessageChain, /*errorOutputContainer*/ undefined); + } + + function checkTypeRelatedToAndOptionallyElaborate( + source: Type, + target: Type, + relation: Map, + errorNode: Node | undefined, + expr: Expression | undefined, + headMessage: DiagnosticMessage | undefined, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + if (isTypeRelatedTo(source, target, relation)) return true; + if (!errorNode || !elaborateError(expr, source, target, relation, headMessage, containingMessageChain, errorOutputContainer)) { + return checkTypeRelatedTo(source, target, relation, errorNode, headMessage, containingMessageChain, errorOutputContainer); + } + return false; + } + + function isOrHasGenericConditional(type: Type): boolean { + return !!(type.flags & TypeFlags.Conditional || (type.flags & TypeFlags.Intersection && some((type as IntersectionType).types, isOrHasGenericConditional))); + } + + function elaborateError( + node: Expression | undefined, + source: Type, + target: Type, + relation: Map, + headMessage: DiagnosticMessage | undefined, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + if (!node || isOrHasGenericConditional(target)) return false; + if ( + !checkTypeRelatedTo(source, target, relation, /*errorNode*/ undefined) + && elaborateDidYouMeanToCallOrConstruct(node, source, target, relation, headMessage, containingMessageChain, errorOutputContainer) + ) { + return true; + } + switch (node.kind) { + case SyntaxKind.AsExpression: + if (!isConstAssertion(node)) { + break; + } + // fallthrough + case SyntaxKind.JsxExpression: + case SyntaxKind.ParenthesizedExpression: + return elaborateError((node as AsExpression | ParenthesizedExpression | JsxExpression).expression, source, target, relation, headMessage, containingMessageChain, errorOutputContainer); + case SyntaxKind.BinaryExpression: + switch ((node as BinaryExpression).operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.CommaToken: + return elaborateError((node as BinaryExpression).right, source, target, relation, headMessage, containingMessageChain, errorOutputContainer); + } + break; + case SyntaxKind.ObjectLiteralExpression: + return elaborateObjectLiteral(node as ObjectLiteralExpression, source, target, relation, containingMessageChain, errorOutputContainer); + case SyntaxKind.ArrayLiteralExpression: + return elaborateArrayLiteral(node as ArrayLiteralExpression, source, target, relation, containingMessageChain, errorOutputContainer); + case SyntaxKind.JsxAttributes: + return elaborateJsxComponents(node as JsxAttributes, source, target, relation, containingMessageChain, errorOutputContainer); + case SyntaxKind.ArrowFunction: + return elaborateArrowFunction(node as ArrowFunction, source, target, relation, containingMessageChain, errorOutputContainer); + } + return false; + } + + function elaborateDidYouMeanToCallOrConstruct( + node: Expression, + source: Type, + target: Type, + relation: Map, + headMessage: DiagnosticMessage | undefined, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + const callSignatures = getSignaturesOfType(source, SignatureKind.Call); + const constructSignatures = getSignaturesOfType(source, SignatureKind.Construct); + for (const signatures of [constructSignatures, callSignatures]) { + if ( + some(signatures, s => { + const returnType = getReturnTypeOfSignature(s); + return !(returnType.flags & (TypeFlags.Any | TypeFlags.Never)) && checkTypeRelatedTo(returnType, target, relation, /*errorNode*/ undefined); + }) + ) { + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + checkTypeAssignableTo(source, target, node, headMessage, containingMessageChain, resultObj); + const diagnostic = resultObj.errors![resultObj.errors!.length - 1]; + addRelatedInfo( + diagnostic, + createDiagnosticForNode( + node, + signatures === constructSignatures ? Diagnostics.Did_you_mean_to_use_new_with_this_expression : Diagnostics.Did_you_mean_to_call_this_expression, + ), + ); + return true; + } + } + return false; + } + + function elaborateArrowFunction( + node: ArrowFunction, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ): boolean { + // Don't elaborate blocks + if (isBlock(node.body)) { + return false; + } + // Or functions with annotated parameter types + if (some(node.parameters, hasType)) { + return false; + } + const sourceSig = getSingleCallSignature(source); + if (!sourceSig) { + return false; + } + const targetSignatures = getSignaturesOfType(target, SignatureKind.Call); + if (!length(targetSignatures)) { + return false; + } + const returnExpression = node.body; + const sourceReturn = getReturnTypeOfSignature(sourceSig); + const targetReturn = getUnionType(map(targetSignatures, getReturnTypeOfSignature)); + if (!checkTypeRelatedTo(sourceReturn, targetReturn, relation, /*errorNode*/ undefined)) { + const elaborated = returnExpression && elaborateError(returnExpression, sourceReturn, targetReturn, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); + if (elaborated) { + return elaborated; + } + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + checkTypeRelatedTo(sourceReturn, targetReturn, relation, returnExpression, /*headMessage*/ undefined, containingMessageChain, resultObj); + if (resultObj.errors) { + if (target.symbol && length(target.symbol.declarations)) { + addRelatedInfo( + resultObj.errors[resultObj.errors.length - 1], + createDiagnosticForNode( + target.symbol.declarations![0], + Diagnostics.The_expected_type_comes_from_the_return_type_of_this_signature, + ), + ); + } + if ( + (getFunctionFlags(node) & FunctionFlags.Async) === 0 + // exclude cases where source itself is promisy - this way we don't make a suggestion when relating + // an IPromise and a Promise that are slightly different + && !getTypeOfPropertyOfType(sourceReturn, "then" as __String) + && checkTypeRelatedTo(createPromiseType(sourceReturn), targetReturn, relation, /*errorNode*/ undefined) + ) { + addRelatedInfo( + resultObj.errors[resultObj.errors.length - 1], + createDiagnosticForNode( + node, + Diagnostics.Did_you_mean_to_mark_this_function_as_async, + ), + ); + } + return true; + } + } + return false; + } + + function getBestMatchIndexedAccessTypeOrUndefined(source: Type, target: Type, nameType: Type) { + const idx = getIndexedAccessTypeOrUndefined(target, nameType); + if (idx) { + return idx; + } + if (target.flags & TypeFlags.Union) { + const best = getBestMatchingType(source, target as UnionType); + if (best) { + return getIndexedAccessTypeOrUndefined(best, nameType); + } + } + } + + function checkExpressionForMutableLocationWithContextualType(next: Expression, sourcePropType: Type) { + pushContextualType(next, sourcePropType, /*isCache*/ false); + const result = checkExpressionForMutableLocation(next, CheckMode.Contextual); + popContextualType(); + return result; + } + + type ElaborationIterator = IterableIterator<{ errorNode: Node; innerExpression: Expression | undefined; nameType: Type; errorMessage?: DiagnosticMessage | undefined; }>; + /** + * For every element returned from the iterator, checks that element to issue an error on a property of that element's type + * If that element would issue an error, we first attempt to dive into that element's inner expression and issue a more specific error by recuring into `elaborateError` + * Otherwise, we issue an error on _every_ element which fail the assignability check + */ + function elaborateElementwise( + iterator: ElaborationIterator, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + // Assignability failure - check each prop individually, and if that fails, fall back on the bad error span + let reportedError = false; + for (const value of iterator) { + const { errorNode: prop, innerExpression: next, nameType, errorMessage } = value; + let targetPropType = getBestMatchIndexedAccessTypeOrUndefined(source, target, nameType); + if (!targetPropType || targetPropType.flags & TypeFlags.IndexedAccess) continue; // Don't elaborate on indexes on generic variables + let sourcePropType = getIndexedAccessTypeOrUndefined(source, nameType); + if (!sourcePropType) continue; + const propName = getPropertyNameFromIndex(nameType, /*accessNode*/ undefined); + if (!checkTypeRelatedTo(sourcePropType, targetPropType, relation, /*errorNode*/ undefined)) { + const elaborated = next && elaborateError(next, sourcePropType, targetPropType, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); + reportedError = true; + if (!elaborated) { + // Issue error on the prop itself, since the prop couldn't elaborate the error + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + // Use the expression type, if available + const specificSource = next ? checkExpressionForMutableLocationWithContextualType(next, sourcePropType) : sourcePropType; + if (exactOptionalPropertyTypes && isExactOptionalPropertyMismatch(specificSource, targetPropType)) { + const diag = createDiagnosticForNode(prop, Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target, typeToString(specificSource), typeToString(targetPropType)); + diagnostics.add(diag); + resultObj.errors = [diag]; + } + else { + const targetIsOptional = !!(propName && (getPropertyOfType(target, propName) || unknownSymbol).flags & SymbolFlags.Optional); + const sourceIsOptional = !!(propName && (getPropertyOfType(source, propName) || unknownSymbol).flags & SymbolFlags.Optional); + targetPropType = removeMissingType(targetPropType, targetIsOptional); + sourcePropType = removeMissingType(sourcePropType, targetIsOptional && sourceIsOptional); + const result = checkTypeRelatedTo(specificSource, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + if (result && specificSource !== sourcePropType) { + // If for whatever reason the expression type doesn't yield an error, make sure we still issue an error on the sourcePropType + checkTypeRelatedTo(sourcePropType, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + } + } + if (resultObj.errors) { + const reportedDiag = resultObj.errors[resultObj.errors.length - 1]; + const propertyName = isTypeUsableAsPropertyName(nameType) ? getPropertyNameFromType(nameType) : undefined; + const targetProp = propertyName !== undefined ? getPropertyOfType(target, propertyName) : undefined; + + let issuedElaboration = false; + if (!targetProp) { + const indexInfo = getApplicableIndexInfo(target, nameType); + if (indexInfo && indexInfo.declaration && !getSourceFileOfNode(indexInfo.declaration).hasNoDefaultLib) { + issuedElaboration = true; + addRelatedInfo(reportedDiag, createDiagnosticForNode(indexInfo.declaration, Diagnostics.The_expected_type_comes_from_this_index_signature)); + } + } + + if (!issuedElaboration && (targetProp && length(targetProp.declarations) || target.symbol && length(target.symbol.declarations))) { + const targetNode = targetProp && length(targetProp.declarations) ? targetProp.declarations![0] : target.symbol.declarations![0]; + if (!getSourceFileOfNode(targetNode).hasNoDefaultLib) { + addRelatedInfo( + reportedDiag, + createDiagnosticForNode( + targetNode, + Diagnostics.The_expected_type_comes_from_property_0_which_is_declared_here_on_type_1, + propertyName && !(nameType.flags & TypeFlags.UniqueESSymbol) ? unescapeLeadingUnderscores(propertyName) : typeToString(nameType), + typeToString(target), + ), + ); + } + } + } + } + } + } + return reportedError; + } + + /** + * Assumes `target` type is assignable to the `Iterable` type, if `Iterable` is defined, + * or that it's an array or tuple-like type, if `Iterable` is not defined. + */ + function elaborateIterableOrArrayLikeTargetElementwise( + iterator: ElaborationIterator, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + const tupleOrArrayLikeTargetParts = filterType(target, isArrayOrTupleLikeType); + const nonTupleOrArrayLikeTargetParts = filterType(target, t => !isArrayOrTupleLikeType(t)); + // If `nonTupleOrArrayLikeTargetParts` is not `never`, then that should mean `Iterable` is defined. + const iterationType = nonTupleOrArrayLikeTargetParts !== neverType + ? getIterationTypeOfIterable(IterationUse.ForOf, IterationTypeKind.Yield, nonTupleOrArrayLikeTargetParts, /*errorNode*/ undefined) + : undefined; + + let reportedError = false; + for (let status = iterator.next(); !status.done; status = iterator.next()) { + const { errorNode: prop, innerExpression: next, nameType, errorMessage } = status.value; + let targetPropType = iterationType; + const targetIndexedPropType = tupleOrArrayLikeTargetParts !== neverType ? getBestMatchIndexedAccessTypeOrUndefined(source, tupleOrArrayLikeTargetParts, nameType) : undefined; + if (targetIndexedPropType && !(targetIndexedPropType.flags & TypeFlags.IndexedAccess)) { // Don't elaborate on indexes on generic variables + targetPropType = iterationType ? getUnionType([iterationType, targetIndexedPropType]) : targetIndexedPropType; + } + if (!targetPropType) continue; + let sourcePropType = getIndexedAccessTypeOrUndefined(source, nameType); + if (!sourcePropType) continue; + const propName = getPropertyNameFromIndex(nameType, /*accessNode*/ undefined); + if (!checkTypeRelatedTo(sourcePropType, targetPropType, relation, /*errorNode*/ undefined)) { + const elaborated = next && elaborateError(next, sourcePropType, targetPropType, relation, /*headMessage*/ undefined, containingMessageChain, errorOutputContainer); + reportedError = true; + if (!elaborated) { + // Issue error on the prop itself, since the prop couldn't elaborate the error + const resultObj: { errors?: Diagnostic[]; } = errorOutputContainer || {}; + // Use the expression type, if available + const specificSource = next ? checkExpressionForMutableLocationWithContextualType(next, sourcePropType) : sourcePropType; + if (exactOptionalPropertyTypes && isExactOptionalPropertyMismatch(specificSource, targetPropType)) { + const diag = createDiagnosticForNode(prop, Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target, typeToString(specificSource), typeToString(targetPropType)); + diagnostics.add(diag); + resultObj.errors = [diag]; + } + else { + const targetIsOptional = !!(propName && (getPropertyOfType(tupleOrArrayLikeTargetParts, propName) || unknownSymbol).flags & SymbolFlags.Optional); + const sourceIsOptional = !!(propName && (getPropertyOfType(source, propName) || unknownSymbol).flags & SymbolFlags.Optional); + targetPropType = removeMissingType(targetPropType, targetIsOptional); + sourcePropType = removeMissingType(sourcePropType, targetIsOptional && sourceIsOptional); + const result = checkTypeRelatedTo(specificSource, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + if (result && specificSource !== sourcePropType) { + // If for whatever reason the expression type doesn't yield an error, make sure we still issue an error on the sourcePropType + checkTypeRelatedTo(sourcePropType, targetPropType, relation, prop, errorMessage, containingMessageChain, resultObj); + } + } + } + } + } + return reportedError; + } + + function* generateJsxAttributes(node: JsxAttributes): ElaborationIterator { + if (!length(node.properties)) return; + for (const prop of node.properties) { + if (isJsxSpreadAttribute(prop) || isHyphenatedJsxName(getTextOfJsxAttributeName(prop.name))) continue; + yield { errorNode: prop.name, innerExpression: prop.initializer, nameType: getStringLiteralType(getTextOfJsxAttributeName(prop.name)) }; + } + } + + function* generateJsxChildren(node: JsxElement, getInvalidTextDiagnostic: () => DiagnosticMessage): ElaborationIterator { + if (!length(node.children)) return; + let memberOffset = 0; + for (let i = 0; i < node.children.length; i++) { + const child = node.children[i]; + const nameType = getNumberLiteralType(i - memberOffset); + const elem = getElaborationElementForJsxChild(child, nameType, getInvalidTextDiagnostic); + if (elem) { + yield elem; + } + else { + memberOffset++; + } + } + } + + function getElaborationElementForJsxChild(child: JsxChild, nameType: LiteralType, getInvalidTextDiagnostic: () => DiagnosticMessage) { + switch (child.kind) { + case SyntaxKind.JsxExpression: + // child is of the type of the expression + return { errorNode: child, innerExpression: child.expression, nameType }; + case SyntaxKind.JsxText: + if (child.containsOnlyTriviaWhiteSpaces) { + break; // Whitespace only jsx text isn't real jsx text + } + // child is a string + return { errorNode: child, innerExpression: undefined, nameType, errorMessage: getInvalidTextDiagnostic() }; + case SyntaxKind.JsxElement: + case SyntaxKind.JsxSelfClosingElement: + case SyntaxKind.JsxFragment: + // child is of type JSX.Element + return { errorNode: child, innerExpression: child, nameType }; + default: + return Debug.assertNever(child, "Found invalid jsx child"); + } + } + + function elaborateJsxComponents( + node: JsxAttributes, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + let result = elaborateElementwise(generateJsxAttributes(node), source, target, relation, containingMessageChain, errorOutputContainer); + let invalidTextDiagnostic: DiagnosticMessage | undefined; + if (isJsxOpeningElement(node.parent) && isJsxElement(node.parent.parent)) { + const containingElement = node.parent.parent; + const childPropName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + const childrenPropName = childPropName === undefined ? "children" : unescapeLeadingUnderscores(childPropName); + const childrenNameType = getStringLiteralType(childrenPropName); + const childrenTargetType = getIndexedAccessType(target, childrenNameType); + const validChildren = getSemanticJsxChildren(containingElement.children); + if (!length(validChildren)) { + return result; + } + const moreThanOneRealChildren = length(validChildren) > 1; + let arrayLikeTargetParts: Type; + let nonArrayLikeTargetParts: Type; + const iterableType = getGlobalIterableType(/*reportErrors*/ false); + if (iterableType !== emptyGenericType) { + const anyIterable = createIterableType(anyType); + arrayLikeTargetParts = filterType(childrenTargetType, t => isTypeAssignableTo(t, anyIterable)); + nonArrayLikeTargetParts = filterType(childrenTargetType, t => !isTypeAssignableTo(t, anyIterable)); + } + else { + arrayLikeTargetParts = filterType(childrenTargetType, isArrayOrTupleLikeType); + nonArrayLikeTargetParts = filterType(childrenTargetType, t => !isArrayOrTupleLikeType(t)); + } + if (moreThanOneRealChildren) { + if (arrayLikeTargetParts !== neverType) { + const realSource = createTupleType(checkJsxChildren(containingElement, CheckMode.Normal)); + const children = generateJsxChildren(containingElement, getInvalidTextualChildDiagnostic); + result = elaborateIterableOrArrayLikeTargetElementwise(children, realSource, arrayLikeTargetParts, relation, containingMessageChain, errorOutputContainer) || result; + } + else if (!isTypeRelatedTo(getIndexedAccessType(source, childrenNameType), childrenTargetType, relation)) { + // arity mismatch + result = true; + const diag = error( + containingElement.openingElement.tagName, + Diagnostics.This_JSX_tag_s_0_prop_expects_a_single_child_of_type_1_but_multiple_children_were_provided, + childrenPropName, + typeToString(childrenTargetType), + ); + if (errorOutputContainer && errorOutputContainer.skipLogging) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + } + } + else { + if (nonArrayLikeTargetParts !== neverType) { + const child = validChildren[0]; + const elem = getElaborationElementForJsxChild(child, childrenNameType, getInvalidTextualChildDiagnostic); + if (elem) { + result = elaborateElementwise( + (function* () { + yield elem; + })(), + source, + target, + relation, + containingMessageChain, + errorOutputContainer, + ) || result; + } + } + else if (!isTypeRelatedTo(getIndexedAccessType(source, childrenNameType), childrenTargetType, relation)) { + // arity mismatch + result = true; + const diag = error( + containingElement.openingElement.tagName, + Diagnostics.This_JSX_tag_s_0_prop_expects_type_1_which_requires_multiple_children_but_only_a_single_child_was_provided, + childrenPropName, + typeToString(childrenTargetType), + ); + if (errorOutputContainer && errorOutputContainer.skipLogging) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + } + } + } + return result; + + function getInvalidTextualChildDiagnostic() { + if (!invalidTextDiagnostic) { + const tagNameText = getTextOfNode(node.parent.tagName); + const childPropName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + const childrenPropName = childPropName === undefined ? "children" : unescapeLeadingUnderscores(childPropName); + const childrenTargetType = getIndexedAccessType(target, getStringLiteralType(childrenPropName)); + const diagnostic = Diagnostics._0_components_don_t_accept_text_as_child_elements_Text_in_JSX_has_the_type_string_but_the_expected_type_of_1_is_2; + invalidTextDiagnostic = { ...diagnostic, key: "!!ALREADY FORMATTED!!", message: formatMessage(diagnostic, tagNameText, childrenPropName, typeToString(childrenTargetType)) }; + } + return invalidTextDiagnostic; + } + } + + function* generateLimitedTupleElements(node: ArrayLiteralExpression, target: Type): ElaborationIterator { + const len = length(node.elements); + if (!len) return; + for (let i = 0; i < len; i++) { + // Skip elements which do not exist in the target - a length error on the tuple overall is likely better than an error on a mismatched index signature + if (isTupleLikeType(target) && !getPropertyOfType(target, ("" + i) as __String)) continue; + const elem = node.elements[i]; + if (isOmittedExpression(elem)) continue; + const nameType = getNumberLiteralType(i); + const checkNode = getEffectiveCheckNode(elem); + yield { errorNode: checkNode, innerExpression: checkNode, nameType }; + } + } + + function elaborateArrayLiteral( + node: ArrayLiteralExpression, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + if (target.flags & (TypeFlags.Primitive | TypeFlags.Never)) return false; + if (isTupleLikeType(source)) { + return elaborateElementwise(generateLimitedTupleElements(node, target), source, target, relation, containingMessageChain, errorOutputContainer); + } + // recreate a tuple from the elements, if possible + // Since we're re-doing the expression type, we need to reapply the contextual type + pushContextualType(node, target, /*isCache*/ false); + const tupleizedType = checkArrayLiteral(node, CheckMode.Contextual, /*forceTuple*/ true); + popContextualType(); + if (isTupleLikeType(tupleizedType)) { + return elaborateElementwise(generateLimitedTupleElements(node, target), tupleizedType, target, relation, containingMessageChain, errorOutputContainer); + } + return false; + } + + function* generateObjectLiteralElements(node: ObjectLiteralExpression): ElaborationIterator { + if (!length(node.properties)) return; + for (const prop of node.properties) { + if (isSpreadAssignment(prop)) continue; + const type = getLiteralTypeFromProperty(getSymbolOfDeclaration(prop), TypeFlags.StringOrNumberLiteralOrUnique); + if (!type || (type.flags & TypeFlags.Never)) { + continue; + } + switch (prop.kind) { + case SyntaxKind.SetAccessor: + case SyntaxKind.GetAccessor: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.ShorthandPropertyAssignment: + yield { errorNode: prop.name, innerExpression: undefined, nameType: type }; + break; + case SyntaxKind.PropertyAssignment: + yield { errorNode: prop.name, innerExpression: prop.initializer, nameType: type, errorMessage: isComputedNonLiteralName(prop.name) ? Diagnostics.Type_of_computed_property_s_value_is_0_which_is_not_assignable_to_type_1 : undefined }; + break; + default: + Debug.assertNever(prop); + } + } + } + + function elaborateObjectLiteral( + node: ObjectLiteralExpression, + source: Type, + target: Type, + relation: Map, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } | undefined, + ) { + if (target.flags & (TypeFlags.Primitive | TypeFlags.Never)) return false; + return elaborateElementwise(generateObjectLiteralElements(node), source, target, relation, containingMessageChain, errorOutputContainer); + } + + /** + * This is *not* a bi-directional relationship. + * If one needs to check both directions for comparability, use a second call to this function or 'isTypeComparableTo'. + */ + function checkTypeComparableTo(source: Type, target: Type, errorNode: Node, headMessage?: DiagnosticMessage, containingMessageChain?: () => DiagnosticMessageChain | undefined): boolean { + return checkTypeRelatedTo(source, target, comparableRelation, errorNode, headMessage, containingMessageChain); + } + + function isSignatureAssignableTo(source: Signature, target: Signature, ignoreReturnTypes: boolean): boolean { + return compareSignaturesRelated(source, target, ignoreReturnTypes ? SignatureCheckMode.IgnoreReturnTypes : SignatureCheckMode.None, /*reportErrors*/ false, /*errorReporter*/ undefined, /*incompatibleErrorReporter*/ undefined, compareTypesAssignable, /*reportUnreliableMarkers*/ undefined) !== Ternary.False; + } + + type ErrorReporter = (message: DiagnosticMessage, ...args: DiagnosticArguments) => void; + + /** + * Returns true if `s` is `(...args: A) => R` where `A` is `any`, `any[]`, `never`, or `never[]`, and `R` is `any` or `unknown`. + */ + function isTopSignature(s: Signature) { + if (!s.typeParameters && (!s.thisParameter || isTypeAny(getTypeOfParameter(s.thisParameter))) && s.parameters.length === 1 && signatureHasRestParameter(s)) { + const paramType = getTypeOfParameter(s.parameters[0]); + const restType = isArrayType(paramType) ? getTypeArguments(paramType)[0] : paramType; + return !!(restType.flags & (TypeFlags.Any | TypeFlags.Never) && getReturnTypeOfSignature(s).flags & TypeFlags.AnyOrUnknown); + } + return false; + } + + /** + * See signatureRelatedTo, compareSignaturesIdentical + */ + function compareSignaturesRelated(source: Signature, target: Signature, checkMode: SignatureCheckMode, reportErrors: boolean, errorReporter: ErrorReporter | undefined, incompatibleErrorReporter: ((source: Type, target: Type) => void) | undefined, compareTypes: TypeComparer, reportUnreliableMarkers: TypeMapper | undefined): Ternary { + // TODO (drosen): De-duplicate code between related functions. + if (source === target) { + return Ternary.True; + } + + if (!(checkMode & SignatureCheckMode.StrictTopSignature && isTopSignature(source)) && isTopSignature(target)) { + return Ternary.True; + } + if (checkMode & SignatureCheckMode.StrictTopSignature && isTopSignature(source) && !isTopSignature(target)) { + return Ternary.False; + } + + const targetCount = getParameterCount(target); + const sourceHasMoreParameters = !hasEffectiveRestParameter(target) && + (checkMode & SignatureCheckMode.StrictArity ? hasEffectiveRestParameter(source) || getParameterCount(source) > targetCount : getMinArgumentCount(source) > targetCount); + if (sourceHasMoreParameters) { + if (reportErrors && !(checkMode & SignatureCheckMode.StrictArity)) { + // the second condition should be redundant, because there is no error reporting when comparing signatures by strict arity + // since it is only done for subtype reduction + errorReporter!(Diagnostics.Target_signature_provides_too_few_arguments_Expected_0_or_more_but_got_1, getMinArgumentCount(source), targetCount); + } + return Ternary.False; + } + + if (source.typeParameters && source.typeParameters !== target.typeParameters) { + target = getCanonicalSignature(target); + source = instantiateSignatureInContextOf(source, target, /*inferenceContext*/ undefined, compareTypes); + } + + const sourceCount = getParameterCount(source); + const sourceRestType = getNonArrayRestType(source); + const targetRestType = getNonArrayRestType(target); + if (sourceRestType || targetRestType) { + void instantiateType(sourceRestType || targetRestType, reportUnreliableMarkers); + } + + const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown; + const strictVariance = !(checkMode & SignatureCheckMode.Callback) && strictFunctionTypes && kind !== SyntaxKind.MethodDeclaration && + kind !== SyntaxKind.MethodSignature && kind !== SyntaxKind.Constructor; + let result = Ternary.True; + + const sourceThisType = getThisTypeOfSignature(source); + if (sourceThisType && sourceThisType !== voidType) { + const targetThisType = getThisTypeOfSignature(target); + if (targetThisType) { + // void sources are assignable to anything. + const related = !strictVariance && compareTypes(sourceThisType, targetThisType, /*reportErrors*/ false) + || compareTypes(targetThisType, sourceThisType, reportErrors); + if (!related) { + if (reportErrors) { + errorReporter!(Diagnostics.The_this_types_of_each_signature_are_incompatible); + } + return Ternary.False; + } + result &= related; + } + } + + const paramCount = sourceRestType || targetRestType ? Math.min(sourceCount, targetCount) : Math.max(sourceCount, targetCount); + const restIndex = sourceRestType || targetRestType ? paramCount - 1 : -1; + + for (let i = 0; i < paramCount; i++) { + const sourceType = i === restIndex ? getRestOrAnyTypeAtPosition(source, i) : tryGetTypeAtPosition(source, i); + const targetType = i === restIndex ? getRestOrAnyTypeAtPosition(target, i) : tryGetTypeAtPosition(target, i); + if (sourceType && targetType && (sourceType !== targetType || checkMode & SignatureCheckMode.StrictArity)) { + // In order to ensure that any generic type Foo is at least co-variant with respect to T no matter + // how Foo uses T, we need to relate parameters bi-variantly (given that parameters are input positions, + // they naturally relate only contra-variantly). However, if the source and target parameters both have + // function types with a single call signature, we know we are relating two callback parameters. In + // that case it is sufficient to only relate the parameters of the signatures co-variantly because, + // similar to return values, callback parameters are output positions. This means that a Promise, + // where T is used only in callback parameter positions, will be co-variant (as opposed to bi-variant) + // with respect to T. + const sourceSig = checkMode & SignatureCheckMode.Callback || isInstantiatedGenericParameter(source, i) ? undefined : getSingleCallSignature(getNonNullableType(sourceType)); + const targetSig = checkMode & SignatureCheckMode.Callback || isInstantiatedGenericParameter(target, i) ? undefined : getSingleCallSignature(getNonNullableType(targetType)); + const callbacks = sourceSig && targetSig && !getTypePredicateOfSignature(sourceSig) && !getTypePredicateOfSignature(targetSig) && + getTypeFacts(sourceType, TypeFacts.IsUndefinedOrNull) === getTypeFacts(targetType, TypeFacts.IsUndefinedOrNull); + let related = callbacks ? + compareSignaturesRelated(targetSig, sourceSig, (checkMode & SignatureCheckMode.StrictArity) | (strictVariance ? SignatureCheckMode.StrictCallback : SignatureCheckMode.BivariantCallback), reportErrors, errorReporter, incompatibleErrorReporter, compareTypes, reportUnreliableMarkers) : + !(checkMode & SignatureCheckMode.Callback) && !strictVariance && compareTypes(sourceType, targetType, /*reportErrors*/ false) || compareTypes(targetType, sourceType, reportErrors); + // With strict arity, (x: number | undefined) => void is a subtype of (x?: number | undefined) => void + if (related && checkMode & SignatureCheckMode.StrictArity && i >= getMinArgumentCount(source) && i < getMinArgumentCount(target) && compareTypes(sourceType, targetType, /*reportErrors*/ false)) { + related = Ternary.False; + } + if (!related) { + if (reportErrors) { + errorReporter!(Diagnostics.Types_of_parameters_0_and_1_are_incompatible, unescapeLeadingUnderscores(getParameterNameAtPosition(source, i)), unescapeLeadingUnderscores(getParameterNameAtPosition(target, i))); + } + return Ternary.False; + } + result &= related; + } + } + + if (!(checkMode & SignatureCheckMode.IgnoreReturnTypes)) { + // If a signature resolution is already in-flight, skip issuing a circularity error + // here and just use the `any` type directly + const targetReturnType = isResolvingReturnTypeOfSignature(target) ? anyType + : target.declaration && isJSConstructor(target.declaration) ? getDeclaredTypeOfClassOrInterface(getMergedSymbol(target.declaration.symbol)) + : getReturnTypeOfSignature(target); + if (targetReturnType === voidType || targetReturnType === anyType) { + return result; + } + const sourceReturnType = isResolvingReturnTypeOfSignature(source) ? anyType + : source.declaration && isJSConstructor(source.declaration) ? getDeclaredTypeOfClassOrInterface(getMergedSymbol(source.declaration.symbol)) + : getReturnTypeOfSignature(source); + + // The following block preserves behavior forbidding boolean returning functions from being assignable to type guard returning functions + const targetTypePredicate = getTypePredicateOfSignature(target); + if (targetTypePredicate) { + const sourceTypePredicate = getTypePredicateOfSignature(source); + if (sourceTypePredicate) { + result &= compareTypePredicateRelatedTo(sourceTypePredicate, targetTypePredicate, reportErrors, errorReporter, compareTypes); + } + else if (isIdentifierTypePredicate(targetTypePredicate) || isThisTypePredicate(targetTypePredicate)) { + if (reportErrors) { + errorReporter!(Diagnostics.Signature_0_must_be_a_type_predicate, signatureToString(source)); + } + return Ternary.False; + } + } + else { + // When relating callback signatures, we still need to relate return types bi-variantly as otherwise + // the containing type wouldn't be co-variant. For example, interface Foo { add(cb: () => T): void } + // wouldn't be co-variant for T without this rule. + result &= checkMode & SignatureCheckMode.BivariantCallback && compareTypes(targetReturnType, sourceReturnType, /*reportErrors*/ false) || + compareTypes(sourceReturnType, targetReturnType, reportErrors); + if (!result && reportErrors && incompatibleErrorReporter) { + incompatibleErrorReporter(sourceReturnType, targetReturnType); + } + } + } + + return result; + } + + function compareTypePredicateRelatedTo( + source: TypePredicate, + target: TypePredicate, + reportErrors: boolean, + errorReporter: ErrorReporter | undefined, + compareTypes: (s: Type, t: Type, reportErrors?: boolean) => Ternary, + ): Ternary { + if (source.kind !== target.kind) { + if (reportErrors) { + errorReporter!(Diagnostics.A_this_based_type_guard_is_not_compatible_with_a_parameter_based_type_guard); + errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); + } + return Ternary.False; + } + + if (source.kind === TypePredicateKind.Identifier || source.kind === TypePredicateKind.AssertsIdentifier) { + if (source.parameterIndex !== (target as IdentifierTypePredicate).parameterIndex) { + if (reportErrors) { + errorReporter!(Diagnostics.Parameter_0_is_not_in_the_same_position_as_parameter_1, source.parameterName, (target as IdentifierTypePredicate).parameterName); + errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); + } + return Ternary.False; + } + } + + const related = source.type === target.type ? Ternary.True : + source.type && target.type ? compareTypes(source.type, target.type, reportErrors) : + Ternary.False; + if (related === Ternary.False && reportErrors) { + errorReporter!(Diagnostics.Type_predicate_0_is_not_assignable_to_1, typePredicateToString(source), typePredicateToString(target)); + } + return related; + } + + function isImplementationCompatibleWithOverload(implementation: Signature, overload: Signature): boolean { + const erasedSource = getErasedSignature(implementation); + const erasedTarget = getErasedSignature(overload); + + // First see if the return types are compatible in either direction. + const sourceReturnType = getReturnTypeOfSignature(erasedSource); + const targetReturnType = getReturnTypeOfSignature(erasedTarget); + if ( + targetReturnType === voidType + || isTypeRelatedTo(targetReturnType, sourceReturnType, assignableRelation) + || isTypeRelatedTo(sourceReturnType, targetReturnType, assignableRelation) + ) { + return isSignatureAssignableTo(erasedSource, erasedTarget, /*ignoreReturnTypes*/ true); + } + + return false; + } + + function isEmptyResolvedType(t: ResolvedType) { + return t !== anyFunctionType && + t.properties.length === 0 && + t.callSignatures.length === 0 && + t.constructSignatures.length === 0 && + t.indexInfos.length === 0; + } + + function isEmptyObjectType(type: Type): boolean { + return type.flags & TypeFlags.Object ? !isGenericMappedType(type) && isEmptyResolvedType(resolveStructuredTypeMembers(type as ObjectType)) : + type.flags & TypeFlags.NonPrimitive ? true : + type.flags & TypeFlags.Union ? some((type as UnionType).types, isEmptyObjectType) : + type.flags & TypeFlags.Intersection ? every((type as UnionType).types, isEmptyObjectType) : + false; + } + + function isEmptyAnonymousObjectType(type: Type) { + return !!(getObjectFlags(type) & ObjectFlags.Anonymous && ( + (type as ResolvedType).members && isEmptyResolvedType(type as ResolvedType) || + type.symbol && type.symbol.flags & SymbolFlags.TypeLiteral && getMembersOfSymbol(type.symbol).size === 0 + )); + } + + function isUnknownLikeUnionType(type: Type) { + if (strictNullChecks && type.flags & TypeFlags.Union) { + if (!((type as UnionType).objectFlags & ObjectFlags.IsUnknownLikeUnionComputed)) { + const types = (type as UnionType).types; + (type as UnionType).objectFlags |= ObjectFlags.IsUnknownLikeUnionComputed | (types.length >= 3 && types[0].flags & TypeFlags.Undefined && + types[1].flags & TypeFlags.Null && some(types, isEmptyAnonymousObjectType) ? ObjectFlags.IsUnknownLikeUnion : 0); + } + return !!((type as UnionType).objectFlags & ObjectFlags.IsUnknownLikeUnion); + } + return false; + } + + function containsUndefinedType(type: Type) { + return !!((type.flags & TypeFlags.Union ? (type as UnionType).types[0] : type).flags & TypeFlags.Undefined); + } + + function isStringIndexSignatureOnlyType(type: Type): boolean { + return type.flags & TypeFlags.Object && !isGenericMappedType(type) && getPropertiesOfType(type).length === 0 && getIndexInfosOfType(type).length === 1 && !!getIndexInfoOfType(type, stringType) || + type.flags & TypeFlags.UnionOrIntersection && every((type as UnionOrIntersectionType).types, isStringIndexSignatureOnlyType) || + false; + } + + function isEnumTypeRelatedTo(source: Symbol, target: Symbol, errorReporter?: ErrorReporter) { + const sourceSymbol = source.flags & SymbolFlags.EnumMember ? getParentOfSymbol(source)! : source; + const targetSymbol = target.flags & SymbolFlags.EnumMember ? getParentOfSymbol(target)! : target; + if (sourceSymbol === targetSymbol) { + return true; + } + if (sourceSymbol.escapedName !== targetSymbol.escapedName || !(sourceSymbol.flags & SymbolFlags.RegularEnum) || !(targetSymbol.flags & SymbolFlags.RegularEnum)) { + return false; + } + const id = getSymbolId(sourceSymbol) + "," + getSymbolId(targetSymbol); + const entry = enumRelation.get(id); + if (entry !== undefined && !(!(entry & RelationComparisonResult.Reported) && entry & RelationComparisonResult.Failed && errorReporter)) { + return !!(entry & RelationComparisonResult.Succeeded); + } + const targetEnumType = getTypeOfSymbol(targetSymbol); + for (const sourceProperty of getPropertiesOfType(getTypeOfSymbol(sourceSymbol))) { + if (sourceProperty.flags & SymbolFlags.EnumMember) { + const targetProperty = getPropertyOfType(targetEnumType, sourceProperty.escapedName); + if (!targetProperty || !(targetProperty.flags & SymbolFlags.EnumMember)) { + if (errorReporter) { + errorReporter(Diagnostics.Property_0_is_missing_in_type_1, symbolName(sourceProperty), typeToString(getDeclaredTypeOfSymbol(targetSymbol), /*enclosingDeclaration*/ undefined, TypeFormatFlags.UseFullyQualifiedType)); + enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); + } + else { + enumRelation.set(id, RelationComparisonResult.Failed); + } + return false; + } + const sourceValue = getEnumMemberValue(getDeclarationOfKind(sourceProperty, SyntaxKind.EnumMember)!).value; + const targetValue = getEnumMemberValue(getDeclarationOfKind(targetProperty, SyntaxKind.EnumMember)!).value; + if (sourceValue !== targetValue) { + const sourceIsString = typeof sourceValue === "string"; + const targetIsString = typeof targetValue === "string"; + + // If we have 2 enums with *known* values that differ, they are incompatible. + if (sourceValue !== undefined && targetValue !== undefined) { + if (!errorReporter) { + enumRelation.set(id, RelationComparisonResult.Failed); + } + else { + const escapedSource = sourceIsString ? `"${escapeString(sourceValue)}"` : sourceValue; + const escapedTarget = targetIsString ? `"${escapeString(targetValue)}"` : targetValue; + errorReporter(Diagnostics.Each_declaration_of_0_1_differs_in_its_value_where_2_was_expected_but_3_was_given, symbolName(targetSymbol), symbolName(targetProperty), escapedTarget, escapedSource); + enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); + } + return false; + } + + // At this point we know that at least one of the values is 'undefined'. + // This may mean that we have an opaque member from an ambient enum declaration, + // or that we were not able to calculate it (which is basically an error). + // + // Either way, we can assume that it's numeric. + // If the other is a string, we have a mismatch in types. + if (sourceIsString || targetIsString) { + if (!errorReporter) { + enumRelation.set(id, RelationComparisonResult.Failed); + } + else { + const knownStringValue = sourceValue ?? targetValue; + Debug.assert(typeof knownStringValue === "string"); + const escapedValue = `"${escapeString(knownStringValue)}"`; + errorReporter(Diagnostics.One_value_of_0_1_is_the_string_2_and_the_other_is_assumed_to_be_an_unknown_numeric_value, symbolName(targetSymbol), symbolName(targetProperty), escapedValue); + enumRelation.set(id, RelationComparisonResult.Failed | RelationComparisonResult.Reported); + } + return false; + } + } + } + } + enumRelation.set(id, RelationComparisonResult.Succeeded); + return true; + } + + function isSimpleTypeRelatedTo(source: Type, target: Type, relation: Map, errorReporter?: ErrorReporter) { + const s = source.flags; + const t = target.flags; + if (t & TypeFlags.Any || s & TypeFlags.Never || source === wildcardType) return true; + if (t & TypeFlags.Unknown && !(relation === strictSubtypeRelation && s & TypeFlags.Any)) return true; + if (t & TypeFlags.Never) return false; + if (s & TypeFlags.StringLike && t & TypeFlags.String) return true; + if ( + s & TypeFlags.StringLiteral && s & TypeFlags.EnumLiteral && + t & TypeFlags.StringLiteral && !(t & TypeFlags.EnumLiteral) && + (source as StringLiteralType).value === (target as StringLiteralType).value + ) return true; + if (s & TypeFlags.NumberLike && t & TypeFlags.Number) return true; + if ( + s & TypeFlags.NumberLiteral && s & TypeFlags.EnumLiteral && + t & TypeFlags.NumberLiteral && !(t & TypeFlags.EnumLiteral) && + (source as NumberLiteralType).value === (target as NumberLiteralType).value + ) return true; + if (s & TypeFlags.BigIntLike && t & TypeFlags.BigInt) return true; + if (s & TypeFlags.BooleanLike && t & TypeFlags.Boolean) return true; + if (s & TypeFlags.ESSymbolLike && t & TypeFlags.ESSymbol) return true; + if ( + s & TypeFlags.Enum && t & TypeFlags.Enum && source.symbol.escapedName === target.symbol.escapedName && + isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter) + ) return true; + if (s & TypeFlags.EnumLiteral && t & TypeFlags.EnumLiteral) { + if (s & TypeFlags.Union && t & TypeFlags.Union && isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter)) return true; + if ( + s & TypeFlags.Literal && t & TypeFlags.Literal && (source as LiteralType).value === (target as LiteralType).value && + isEnumTypeRelatedTo(source.symbol, target.symbol, errorReporter) + ) return true; + } + // In non-strictNullChecks mode, `undefined` and `null` are assignable to anything except `never`. + // Since unions and intersections may reduce to `never`, we exclude them here. + if (s & TypeFlags.Undefined && (!strictNullChecks && !(t & TypeFlags.UnionOrIntersection) || t & (TypeFlags.Undefined | TypeFlags.Void))) return true; + if (s & TypeFlags.Null && (!strictNullChecks && !(t & TypeFlags.UnionOrIntersection) || t & TypeFlags.Null)) return true; + if (s & TypeFlags.Object && t & TypeFlags.NonPrimitive && !(relation === strictSubtypeRelation && isEmptyAnonymousObjectType(source) && !(getObjectFlags(source) & ObjectFlags.FreshLiteral))) return true; + if (relation === assignableRelation || relation === comparableRelation) { + if (s & TypeFlags.Any) return true; + // Type number is assignable to any computed numeric enum type or any numeric enum literal type, and + // a numeric literal type is assignable any computed numeric enum type or any numeric enum literal type + // with a matching value. These rules exist such that enums can be used for bit-flag purposes. + if (s & TypeFlags.Number && (t & TypeFlags.Enum || t & TypeFlags.NumberLiteral && t & TypeFlags.EnumLiteral)) return true; + if ( + s & TypeFlags.NumberLiteral && !(s & TypeFlags.EnumLiteral) && (t & TypeFlags.Enum || + t & TypeFlags.NumberLiteral && t & TypeFlags.EnumLiteral && + (source as NumberLiteralType).value === (target as NumberLiteralType).value) + ) return true; + // Anything is assignable to a union containing undefined, null, and {} + if (isUnknownLikeUnionType(target)) return true; + } + return false; + } + + function isTypeRelatedTo(source: Type, target: Type, relation: Map) { + if (isFreshLiteralType(source)) { + source = (source as FreshableType).regularType; + } + if (isFreshLiteralType(target)) { + target = (target as FreshableType).regularType; + } + if (source === target) { + return true; + } + if (relation !== identityRelation) { + if (relation === comparableRelation && !(target.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(target, source, relation) || isSimpleTypeRelatedTo(source, target, relation)) { + return true; + } + } + else if (!((source.flags | target.flags) & (TypeFlags.UnionOrIntersection | TypeFlags.IndexedAccess | TypeFlags.Conditional | TypeFlags.Substitution))) { + // We have excluded types that may simplify to other forms, so types must have identical flags + if (source.flags !== target.flags) return false; + if (source.flags & TypeFlags.Singleton) return true; + } + if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) { + const related = relation.get(getRelationKey(source, target, IntersectionState.None, relation, /*ignoreConstraints*/ false)); + if (related !== undefined) { + return !!(related & RelationComparisonResult.Succeeded); + } + } + if (source.flags & TypeFlags.StructuredOrInstantiable || target.flags & TypeFlags.StructuredOrInstantiable) { + return checkTypeRelatedTo(source, target, relation, /*errorNode*/ undefined); + } + return false; + } + + function isIgnoredJsxProperty(source: Type, sourceProp: Symbol) { + return getObjectFlags(source) & ObjectFlags.JsxAttributes && isHyphenatedJsxName(sourceProp.escapedName); + } + + function getNormalizedType(type: Type, writing: boolean): Type { + while (true) { + const t = isFreshLiteralType(type) ? (type as FreshableType).regularType : + isGenericTupleType(type) ? getNormalizedTupleType(type, writing) : + getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).node ? createTypeReference((type as TypeReference).target, getTypeArguments(type as TypeReference)) : getSingleBaseForNonAugmentingSubtype(type) || type : + type.flags & TypeFlags.UnionOrIntersection ? getNormalizedUnionOrIntersectionType(type as UnionOrIntersectionType, writing) : + type.flags & TypeFlags.Substitution ? writing ? (type as SubstitutionType).baseType : getSubstitutionIntersection(type as SubstitutionType) : + type.flags & TypeFlags.Simplifiable ? getSimplifiedType(type, writing) : + type; + if (t === type) return t; + type = t; + } + } + + function getNormalizedUnionOrIntersectionType(type: UnionOrIntersectionType, writing: boolean) { + const reduced = getReducedType(type); + if (reduced !== type) { + return reduced; + } + if (type.flags & TypeFlags.Intersection && shouldNormalizeIntersection(type as IntersectionType)) { + // Normalization handles cases like + // Partial[K] & ({} | null) ==> + // Partial[K] & {} | Partial[K} & null ==> + // (T[K] | undefined) & {} | (T[K] | undefined) & null ==> + // T[K] & {} | undefined & {} | T[K] & null | undefined & null ==> + // T[K] & {} | T[K] & null + const normalizedTypes = sameMap(type.types, t => getNormalizedType(t, writing)); + if (normalizedTypes !== type.types) { + return getIntersectionType(normalizedTypes); + } + } + return type; + } + + function shouldNormalizeIntersection(type: IntersectionType) { + let hasInstantiable = false; + let hasNullableOrEmpty = false; + for (const t of type.types) { + hasInstantiable ||= !!(t.flags & TypeFlags.Instantiable); + hasNullableOrEmpty ||= !!(t.flags & TypeFlags.Nullable) || isEmptyAnonymousObjectType(t); + if (hasInstantiable && hasNullableOrEmpty) return true; + } + return false; + } + + function getNormalizedTupleType(type: TupleTypeReference, writing: boolean): Type { + const elements = getElementTypes(type); + const normalizedElements = sameMap(elements, t => t.flags & TypeFlags.Simplifiable ? getSimplifiedType(t, writing) : t); + return elements !== normalizedElements ? createNormalizedTupleType(type.target, normalizedElements) : type; + } + + /** + * Checks if 'source' is related to 'target' (e.g.: is a assignable to). + * @param source The left-hand-side of the relation. + * @param target The right-hand-side of the relation. + * @param relation The relation considered. One of 'identityRelation', 'subtypeRelation', 'assignableRelation', or 'comparableRelation'. + * Used as both to determine which checks are performed and as a cache of previously computed results. + * @param errorNode The suggested node upon which all errors will be reported, if defined. This may or may not be the actual node used. + * @param headMessage If the error chain should be prepended by a head message, then headMessage will be used. + * @param containingMessageChain A chain of errors to prepend any new errors found. + * @param errorOutputContainer Return the diagnostic. Do not log if 'skipLogging' is truthy. + */ + function checkTypeRelatedTo( + source: Type, + target: Type, + relation: Map, + errorNode: Node | undefined, + headMessage?: DiagnosticMessage, + containingMessageChain?: () => DiagnosticMessageChain | undefined, + errorOutputContainer?: { errors?: Diagnostic[]; skipLogging?: boolean; }, + ): boolean { + let errorInfo: DiagnosticMessageChain | undefined; + let relatedInfo: [DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined; + let maybeKeys: string[]; + let maybeKeysSet: Set; + let sourceStack: Type[]; + let targetStack: Type[]; + let maybeCount = 0; + let sourceDepth = 0; + let targetDepth = 0; + let expandingFlags = ExpandingFlags.None; + let overflow = false; + let overrideNextErrorInfo = 0; // How many `reportRelationError` calls should be skipped in the elaboration pyramid + let skipParentCounter = 0; // How many errors should be skipped 'above' in the elaboration pyramid + let lastSkippedInfo: [Type, Type] | undefined; + let incompatibleStack: DiagnosticAndArguments[] | undefined; + // In Node.js, the maximum number of elements in a map is 2^24. We limit the number of entries an invocation + // of checkTypeRelatedTo can add to a relation to 1/8th of its remaining capacity. + let relationCount = (16_000_000 - relation.size) >> 3; + + Debug.assert(relation !== identityRelation || !errorNode, "no error reporting in identity checking"); + + const result = isRelatedTo(source, target, RecursionFlags.Both, /*reportErrors*/ !!errorNode, headMessage); + if (incompatibleStack) { + reportIncompatibleStack(); + } + if (overflow) { + // Record this relation as having failed such that we don't attempt the overflowing operation again. + const id = getRelationKey(source, target, /*intersectionState*/ IntersectionState.None, relation, /*ignoreConstraints*/ false); + relation.set(id, RelationComparisonResult.Reported | RelationComparisonResult.Failed); + tracing?.instant(tracing.Phase.CheckTypes, "checkTypeRelatedTo_DepthLimit", { sourceId: source.id, targetId: target.id, depth: sourceDepth, targetDepth }); + const message = relationCount <= 0 ? + Diagnostics.Excessive_complexity_comparing_types_0_and_1 : + Diagnostics.Excessive_stack_depth_comparing_types_0_and_1; + const diag = error(errorNode || currentNode, message, typeToString(source), typeToString(target)); + if (errorOutputContainer) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + } + else if (errorInfo) { + if (containingMessageChain) { + const chain = containingMessageChain(); + if (chain) { + concatenateDiagnosticMessageChains(chain, errorInfo); + errorInfo = chain; + } + } + + let relatedInformation: DiagnosticRelatedInformation[] | undefined; + // Check if we should issue an extra diagnostic to produce a quickfix for a slightly incorrect import statement + if (headMessage && errorNode && !result && source.symbol) { + const links = getSymbolLinks(source.symbol); + if (links.originatingImport && !isImportCall(links.originatingImport)) { + const helpfulRetry = checkTypeRelatedTo(getTypeOfSymbol(links.target!), target, relation, /*errorNode*/ undefined); + if (helpfulRetry) { + // Likely an incorrect import. Issue a helpful diagnostic to produce a quickfix to change the import + const diag = createDiagnosticForNode(links.originatingImport, Diagnostics.Type_originates_at_this_import_A_namespace_style_import_cannot_be_called_or_constructed_and_will_cause_a_failure_at_runtime_Consider_using_a_default_import_or_import_require_here_instead); + relatedInformation = append(relatedInformation, diag); // Cause the error to appear with the error that triggered it + } + } + } + const diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorNode!), errorNode!, errorInfo, relatedInformation); + if (relatedInfo) { + addRelatedInfo(diag, ...relatedInfo); + } + if (errorOutputContainer) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + if (!errorOutputContainer || !errorOutputContainer.skipLogging) { + diagnostics.add(diag); + } + } + if (errorNode && errorOutputContainer && errorOutputContainer.skipLogging && result === Ternary.False) { + Debug.assert(!!errorOutputContainer.errors, "missed opportunity to interact with error."); + } + + return result !== Ternary.False; + + function resetErrorInfo(saved: ReturnType) { + errorInfo = saved.errorInfo; + lastSkippedInfo = saved.lastSkippedInfo; + incompatibleStack = saved.incompatibleStack; + overrideNextErrorInfo = saved.overrideNextErrorInfo; + skipParentCounter = saved.skipParentCounter; + relatedInfo = saved.relatedInfo; + } + + function captureErrorCalculationState() { + return { + errorInfo, + lastSkippedInfo, + incompatibleStack: incompatibleStack?.slice(), + overrideNextErrorInfo, + skipParentCounter, + relatedInfo: relatedInfo?.slice() as [DiagnosticRelatedInformation, ...DiagnosticRelatedInformation[]] | undefined, + }; + } + + function reportIncompatibleError(message: DiagnosticMessage, ...args: DiagnosticArguments) { + overrideNextErrorInfo++; // Suppress the next relation error + lastSkippedInfo = undefined; // Reset skipped info cache + (incompatibleStack ||= []).push([message, ...args]); + } + + function reportIncompatibleStack() { + const stack = incompatibleStack || []; + incompatibleStack = undefined; + const info = lastSkippedInfo; + lastSkippedInfo = undefined; + if (stack.length === 1) { + reportError(...stack[0]); + if (info) { + // Actually do the last relation error + reportRelationError(/*message*/ undefined, ...info); + } + return; + } + // The first error will be the innermost, while the last will be the outermost - so by popping off the end, + // we can build from left to right + let path = ""; + const secondaryRootErrors: DiagnosticAndArguments[] = []; + while (stack.length) { + const [msg, ...args] = stack.pop()!; + switch (msg.code) { + case Diagnostics.Types_of_property_0_are_incompatible.code: { + // Parenthesize a `new` if there is one + if (path.indexOf("new ") === 0) { + path = `(${path})`; + } + const str = "" + args[0]; + // If leading, just print back the arg (irrespective of if it's a valid identifier) + if (path.length === 0) { + path = `${str}`; + } + // Otherwise write a dotted name if possible + else if (isIdentifierText(str, getEmitScriptTarget(compilerOptions))) { + path = `${path}.${str}`; + } + // Failing that, check if the name is already a computed name + else if (str[0] === "[" && str[str.length - 1] === "]") { + path = `${path}${str}`; + } + // And finally write out a computed name as a last resort + else { + path = `${path}[${str}]`; + } + break; + } + case Diagnostics.Call_signature_return_types_0_and_1_are_incompatible.code: + case Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code: + case Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code: + case Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code: { + if (path.length === 0) { + // Don't flatten signature compatability errors at the start of a chain - instead prefer + // to unify (the with no arguments bit is excessive for printback) and print them back + let mappedMsg = msg; + if (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) { + mappedMsg = Diagnostics.Call_signature_return_types_0_and_1_are_incompatible; + } + else if (msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) { + mappedMsg = Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible; + } + secondaryRootErrors.unshift([mappedMsg, args[0], args[1]]); + } + else { + const prefix = (msg.code === Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible.code || + msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) + ? "new " + : ""; + const params = (msg.code === Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code || + msg.code === Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1.code) + ? "" + : "..."; + path = `${prefix}${path}(${params})`; + } + break; + } + case Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target.code: { + secondaryRootErrors.unshift([Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target, args[0], args[1]]); + break; + } + case Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target.code: { + secondaryRootErrors.unshift([Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target, args[0], args[1], args[2]]); + break; + } + default: + return Debug.fail(`Unhandled Diagnostic: ${msg.code}`); + } + } + if (path) { + reportError( + path[path.length - 1] === ")" + ? Diagnostics.The_types_returned_by_0_are_incompatible_between_these_types + : Diagnostics.The_types_of_0_are_incompatible_between_these_types, + path, + ); + } + else { + // Remove the innermost secondary error as it will duplicate the error already reported by `reportRelationError` on entry + secondaryRootErrors.shift(); + } + for (const [msg, ...args] of secondaryRootErrors) { + const originalValue = msg.elidedInCompatabilityPyramid; + msg.elidedInCompatabilityPyramid = false; // Temporarily override elision to ensure error is reported + reportError(msg, ...args); + msg.elidedInCompatabilityPyramid = originalValue; + } + if (info) { + // Actually do the last relation error + reportRelationError(/*message*/ undefined, ...info); + } + } + + function reportError(message: DiagnosticMessage, ...args: DiagnosticArguments): void { + Debug.assert(!!errorNode); + if (incompatibleStack) reportIncompatibleStack(); + if (message.elidedInCompatabilityPyramid) return; + if (skipParentCounter === 0) { + errorInfo = chainDiagnosticMessages(errorInfo, message, ...args); + } + else { + skipParentCounter--; + } + } + + function reportParentSkippedError(message: DiagnosticMessage, ...args: DiagnosticArguments): void { + reportError(message, ...args); + skipParentCounter++; + } + + function associateRelatedInfo(info: DiagnosticRelatedInformation) { + Debug.assert(!!errorInfo); + if (!relatedInfo) { + relatedInfo = [info]; + } + else { + relatedInfo.push(info); + } + } + + function reportRelationError(message: DiagnosticMessage | undefined, source: Type, target: Type) { + if (incompatibleStack) reportIncompatibleStack(); + const [sourceType, targetType] = getTypeNamesForErrorDisplay(source, target); + let generalizedSource = source; + let generalizedSourceType = sourceType; + + if (isLiteralType(source) && !typeCouldHaveTopLevelSingletonTypes(target)) { + generalizedSource = getBaseTypeOfLiteralType(source); + Debug.assert(!isTypeAssignableTo(generalizedSource, target), "generalized source shouldn't be assignable"); + generalizedSourceType = getTypeNameForErrorDisplay(generalizedSource); + } + + // If `target` is of indexed access type (And `source` it is not), we use the object type of `target` for better error reporting + const targetFlags = target.flags & TypeFlags.IndexedAccess && !(source.flags & TypeFlags.IndexedAccess) ? + (target as IndexedAccessType).objectType.flags : + target.flags; + + if (targetFlags & TypeFlags.TypeParameter && target !== markerSuperTypeForCheck && target !== markerSubTypeForCheck) { + const constraint = getBaseConstraintOfType(target); + let needsOriginalSource; + if (constraint && (isTypeAssignableTo(generalizedSource, constraint) || (needsOriginalSource = isTypeAssignableTo(source, constraint)))) { + reportError( + Diagnostics._0_is_assignable_to_the_constraint_of_type_1_but_1_could_be_instantiated_with_a_different_subtype_of_constraint_2, + needsOriginalSource ? sourceType : generalizedSourceType, + targetType, + typeToString(constraint), + ); + } + else { + errorInfo = undefined; + reportError( + Diagnostics._0_could_be_instantiated_with_an_arbitrary_type_which_could_be_unrelated_to_1, + targetType, + generalizedSourceType, + ); + } + } + + if (!message) { + if (relation === comparableRelation) { + message = Diagnostics.Type_0_is_not_comparable_to_type_1; + } + else if (sourceType === targetType) { + message = Diagnostics.Type_0_is_not_assignable_to_type_1_Two_different_types_with_this_name_exist_but_they_are_unrelated; + } + else if (exactOptionalPropertyTypes && getExactOptionalUnassignableProperties(source, target).length) { + message = Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties; + } + else { + if (source.flags & TypeFlags.StringLiteral && target.flags & TypeFlags.Union) { + const suggestedType = getSuggestedTypeForNonexistentStringLiteralType(source as StringLiteralType, target as UnionType); + if (suggestedType) { + reportError(Diagnostics.Type_0_is_not_assignable_to_type_1_Did_you_mean_2, generalizedSourceType, targetType, typeToString(suggestedType)); + return; + } + } + message = Diagnostics.Type_0_is_not_assignable_to_type_1; + } + } + else if ( + message === Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1 + && exactOptionalPropertyTypes + && getExactOptionalUnassignableProperties(source, target).length + ) { + message = Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_types_of_the_target_s_properties; + } + + reportError(message, generalizedSourceType, targetType); + } + + function tryElaborateErrorsForPrimitivesAndObjects(source: Type, target: Type) { + const sourceType = symbolValueDeclarationIsContextSensitive(source.symbol) ? typeToString(source, source.symbol.valueDeclaration) : typeToString(source); + const targetType = symbolValueDeclarationIsContextSensitive(target.symbol) ? typeToString(target, target.symbol.valueDeclaration) : typeToString(target); + + if ( + (globalStringType === source && stringType === target) || + (globalNumberType === source && numberType === target) || + (globalBooleanType === source && booleanType === target) || + (getGlobalESSymbolType() === source && esSymbolType === target) + ) { + reportError(Diagnostics._0_is_a_primitive_but_1_is_a_wrapper_object_Prefer_using_0_when_possible, targetType, sourceType); + } + } + + /** + * Try and elaborate array and tuple errors. Returns false + * if we have found an elaboration, or we should ignore + * any other elaborations when relating the `source` and + * `target` types. + */ + function tryElaborateArrayLikeErrors(source: Type, target: Type, reportErrors: boolean): boolean { + /** + * The spec for elaboration is: + * - If the source is a readonly tuple and the target is a mutable array or tuple, elaborate on mutability and skip property elaborations. + * - If the source is a tuple then skip property elaborations if the target is an array or tuple. + * - If the source is a readonly array and the target is a mutable array or tuple, elaborate on mutability and skip property elaborations. + * - If the source an array then skip property elaborations if the target is a tuple. + */ + if (isTupleType(source)) { + if (source.target.readonly && isMutableArrayOrTuple(target)) { + if (reportErrors) { + reportError(Diagnostics.The_type_0_is_readonly_and_cannot_be_assigned_to_the_mutable_type_1, typeToString(source), typeToString(target)); + } + return false; + } + return isArrayOrTupleType(target); + } + if (isReadonlyArrayType(source) && isMutableArrayOrTuple(target)) { + if (reportErrors) { + reportError(Diagnostics.The_type_0_is_readonly_and_cannot_be_assigned_to_the_mutable_type_1, typeToString(source), typeToString(target)); + } + return false; + } + if (isTupleType(target)) { + return isArrayType(source); + } + return true; + } + + function isRelatedToWorker(source: Type, target: Type, reportErrors?: boolean) { + return isRelatedTo(source, target, RecursionFlags.Both, reportErrors); + } + + /** + * Compare two types and return + * * Ternary.True if they are related with no assumptions, + * * Ternary.Maybe if they are related with assumptions of other relationships, or + * * Ternary.False if they are not related. + */ + function isRelatedTo(originalSource: Type, originalTarget: Type, recursionFlags: RecursionFlags = RecursionFlags.Both, reportErrors = false, headMessage?: DiagnosticMessage, intersectionState = IntersectionState.None): Ternary { + if (originalSource === originalTarget) return Ternary.True; + + // Before normalization: if `source` is type an object type, and `target` is primitive, + // skip all the checks we don't need and just return `isSimpleTypeRelatedTo` result + if (originalSource.flags & TypeFlags.Object && originalTarget.flags & TypeFlags.Primitive) { + if ( + relation === comparableRelation && !(originalTarget.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(originalTarget, originalSource, relation) || + isSimpleTypeRelatedTo(originalSource, originalTarget, relation, reportErrors ? reportError : undefined) + ) { + return Ternary.True; + } + if (reportErrors) { + reportErrorResults(originalSource, originalTarget, originalSource, originalTarget, headMessage); + } + return Ternary.False; + } + + // Normalize the source and target types: Turn fresh literal types into regular literal types, + // turn deferred type references into regular type references, simplify indexed access and + // conditional types, and resolve substitution types to either the substitution (on the source + // side) or the type variable (on the target side). + const source = getNormalizedType(originalSource, /*writing*/ false); + let target = getNormalizedType(originalTarget, /*writing*/ true); + + if (source === target) return Ternary.True; + + if (relation === identityRelation) { + if (source.flags !== target.flags) return Ternary.False; + if (source.flags & TypeFlags.Singleton) return Ternary.True; + traceUnionsOrIntersectionsTooLarge(source, target); + return recursiveTypeRelatedTo(source, target, /*reportErrors*/ false, IntersectionState.None, recursionFlags); + } + + // We fastpath comparing a type parameter to exactly its constraint, as this is _super_ common, + // and otherwise, for type parameters in large unions, causes us to need to compare the union to itself, + // as we break down the _target_ union first, _then_ get the source constraint - so for every + // member of the target, we attempt to find a match in the source. This avoids that in cases where + // the target is exactly the constraint. + if (source.flags & TypeFlags.TypeParameter && getConstraintOfType(source) === target) { + return Ternary.True; + } + + // See if we're relating a definitely non-nullable type to a union that includes null and/or undefined + // plus a single non-nullable type. If so, remove null and/or undefined from the target type. + if (source.flags & TypeFlags.DefinitelyNonNullable && target.flags & TypeFlags.Union) { + const types = (target as UnionType).types; + const candidate = types.length === 2 && types[0].flags & TypeFlags.Nullable ? types[1] : + types.length === 3 && types[0].flags & TypeFlags.Nullable && types[1].flags & TypeFlags.Nullable ? types[2] : + undefined; + if (candidate && !(candidate.flags & TypeFlags.Nullable)) { + target = getNormalizedType(candidate, /*writing*/ true); + if (source === target) return Ternary.True; + } + } + + if ( + relation === comparableRelation && !(target.flags & TypeFlags.Never) && isSimpleTypeRelatedTo(target, source, relation) || + isSimpleTypeRelatedTo(source, target, relation, reportErrors ? reportError : undefined) + ) return Ternary.True; + + if (source.flags & TypeFlags.StructuredOrInstantiable || target.flags & TypeFlags.StructuredOrInstantiable) { + const isPerformingExcessPropertyChecks = !(intersectionState & IntersectionState.Target) && (isObjectLiteralType(source) && getObjectFlags(source) & ObjectFlags.FreshLiteral); + if (isPerformingExcessPropertyChecks) { + if (hasExcessProperties(source as FreshObjectLiteralType, target, reportErrors)) { + if (reportErrors) { + reportRelationError(headMessage, source, originalTarget.aliasSymbol ? originalTarget : target); + } + return Ternary.False; + } + } + + const isPerformingCommonPropertyChecks = (relation !== comparableRelation || isUnitType(source)) && + !(intersectionState & IntersectionState.Target) && + source.flags & (TypeFlags.Primitive | TypeFlags.Object | TypeFlags.Intersection) && source !== globalObjectType && + target.flags & (TypeFlags.Object | TypeFlags.Intersection) && isWeakType(target) && + (getPropertiesOfType(source).length > 0 || typeHasCallOrConstructSignatures(source)); + const isComparingJsxAttributes = !!(getObjectFlags(source) & ObjectFlags.JsxAttributes); + if (isPerformingCommonPropertyChecks && !hasCommonProperties(source, target, isComparingJsxAttributes)) { + if (reportErrors) { + const sourceString = typeToString(originalSource.aliasSymbol ? originalSource : source); + const targetString = typeToString(originalTarget.aliasSymbol ? originalTarget : target); + const calls = getSignaturesOfType(source, SignatureKind.Call); + const constructs = getSignaturesOfType(source, SignatureKind.Construct); + if ( + calls.length > 0 && isRelatedTo(getReturnTypeOfSignature(calls[0]), target, RecursionFlags.Source, /*reportErrors*/ false) || + constructs.length > 0 && isRelatedTo(getReturnTypeOfSignature(constructs[0]), target, RecursionFlags.Source, /*reportErrors*/ false) + ) { + reportError(Diagnostics.Value_of_type_0_has_no_properties_in_common_with_type_1_Did_you_mean_to_call_it, sourceString, targetString); + } + else { + reportError(Diagnostics.Type_0_has_no_properties_in_common_with_type_1, sourceString, targetString); + } + } + return Ternary.False; + } + + traceUnionsOrIntersectionsTooLarge(source, target); + + const skipCaching = source.flags & TypeFlags.Union && (source as UnionType).types.length < 4 && !(target.flags & TypeFlags.Union) || + target.flags & TypeFlags.Union && (target as UnionType).types.length < 4 && !(source.flags & TypeFlags.StructuredOrInstantiable); + const result = skipCaching ? + unionOrIntersectionRelatedTo(source, target, reportErrors, intersectionState) : + recursiveTypeRelatedTo(source, target, reportErrors, intersectionState, recursionFlags); + if (result) { + return result; + } + } + + if (reportErrors) { + reportErrorResults(originalSource, originalTarget, source, target, headMessage); + } + return Ternary.False; + } + + function reportErrorResults(originalSource: Type, originalTarget: Type, source: Type, target: Type, headMessage: DiagnosticMessage | undefined) { + const sourceHasBase = !!getSingleBaseForNonAugmentingSubtype(originalSource); + const targetHasBase = !!getSingleBaseForNonAugmentingSubtype(originalTarget); + source = (originalSource.aliasSymbol || sourceHasBase) ? originalSource : source; + target = (originalTarget.aliasSymbol || targetHasBase) ? originalTarget : target; + let maybeSuppress = overrideNextErrorInfo > 0; + if (maybeSuppress) { + overrideNextErrorInfo--; + } + if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Object) { + const currentError = errorInfo; + tryElaborateArrayLikeErrors(source, target, /*reportErrors*/ true); + if (errorInfo !== currentError) { + maybeSuppress = !!errorInfo; + } + } + if (source.flags & TypeFlags.Object && target.flags & TypeFlags.Primitive) { + tryElaborateErrorsForPrimitivesAndObjects(source, target); + } + else if (source.symbol && source.flags & TypeFlags.Object && globalObjectType === source) { + reportError(Diagnostics.The_Object_type_is_assignable_to_very_few_other_types_Did_you_mean_to_use_the_any_type_instead); + } + else if (getObjectFlags(source) & ObjectFlags.JsxAttributes && target.flags & TypeFlags.Intersection) { + const targetTypes = (target as IntersectionType).types; + const intrinsicAttributes = getJsxType(JsxNames.IntrinsicAttributes, errorNode); + const intrinsicClassAttributes = getJsxType(JsxNames.IntrinsicClassAttributes, errorNode); + if ( + !isErrorType(intrinsicAttributes) && !isErrorType(intrinsicClassAttributes) && + (contains(targetTypes, intrinsicAttributes) || contains(targetTypes, intrinsicClassAttributes)) + ) { + // do not report top error + return; + } + } + else { + errorInfo = elaborateNeverIntersection(errorInfo, originalTarget); + } + // Used by, eg, missing property checking to replace the top-level message with a more informative one. + if (!headMessage && maybeSuppress) { + // We suppress a call to `reportRelationError` or not depending on the state of the type checker, so + // we call `reportRelationError` here and then undo its effects to figure out what would be the diagnostic + // if we hadn't supress it, and save that as a canonical diagnostic for deduplication purposes. + const savedErrorState = captureErrorCalculationState(); + reportRelationError(headMessage, source, target); + let canonical; + if (errorInfo && errorInfo !== savedErrorState.errorInfo) { + canonical = { code: errorInfo.code, messageText: errorInfo.messageText }; + } + resetErrorInfo(savedErrorState); + if (canonical && errorInfo) { + errorInfo.canonicalHead = canonical; + } + + lastSkippedInfo = [source, target]; + return; + } + reportRelationError(headMessage, source, target); + if (source.flags & TypeFlags.TypeParameter && source.symbol?.declarations?.[0] && !getConstraintOfType(source as TypeVariable)) { + const syntheticParam = cloneTypeParameter(source as TypeParameter); + syntheticParam.constraint = instantiateType(target, makeUnaryTypeMapper(source, syntheticParam)); + if (hasNonCircularBaseConstraint(syntheticParam)) { + const targetConstraintString = typeToString(target, source.symbol.declarations[0]); + associateRelatedInfo(createDiagnosticForNode(source.symbol.declarations[0], Diagnostics.This_type_parameter_might_need_an_extends_0_constraint, targetConstraintString)); + } + } + } + + function traceUnionsOrIntersectionsTooLarge(source: Type, target: Type): void { + if (!tracing) { + return; + } + + if ((source.flags & TypeFlags.UnionOrIntersection) && (target.flags & TypeFlags.UnionOrIntersection)) { + const sourceUnionOrIntersection = source as UnionOrIntersectionType; + const targetUnionOrIntersection = target as UnionOrIntersectionType; + + if (sourceUnionOrIntersection.objectFlags & targetUnionOrIntersection.objectFlags & ObjectFlags.PrimitiveUnion) { + // There's a fast path for comparing primitive unions + return; + } + + const sourceSize = sourceUnionOrIntersection.types.length; + const targetSize = targetUnionOrIntersection.types.length; + if (sourceSize * targetSize > 1E6) { + tracing.instant(tracing.Phase.CheckTypes, "traceUnionsOrIntersectionsTooLarge_DepthLimit", { + sourceId: source.id, + sourceSize, + targetId: target.id, + targetSize, + pos: errorNode?.pos, + end: errorNode?.end, + }); + } + } + } + + function getTypeOfPropertyInTypes(types: Type[], name: __String) { + const appendPropType = (propTypes: Type[] | undefined, type: Type) => { + type = getApparentType(type); + const prop = type.flags & TypeFlags.UnionOrIntersection ? getPropertyOfUnionOrIntersectionType(type as UnionOrIntersectionType, name) : getPropertyOfObjectType(type, name); + const propType = prop && getTypeOfSymbol(prop) || getApplicableIndexInfoForName(type, name)?.type || undefinedType; + return append(propTypes, propType); + }; + return getUnionType(reduceLeft(types, appendPropType, /*initial*/ undefined) || emptyArray); + } + + function hasExcessProperties(source: FreshObjectLiteralType, target: Type, reportErrors: boolean): boolean { + if (!isExcessPropertyCheckTarget(target) || !noImplicitAny && getObjectFlags(target) & ObjectFlags.JSLiteral) { + return false; // Disable excess property checks on JS literals to simulate having an implicit "index signature" - but only outside of noImplicitAny + } + const isComparingJsxAttributes = !!(getObjectFlags(source) & ObjectFlags.JsxAttributes); + if ( + (relation === assignableRelation || relation === comparableRelation) && + (isTypeSubsetOf(globalObjectType, target) || (!isComparingJsxAttributes && isEmptyObjectType(target))) + ) { + return false; + } + let reducedTarget = target; + let checkTypes: Type[] | undefined; + if (target.flags & TypeFlags.Union) { + reducedTarget = findMatchingDiscriminantType(source, target as UnionType, isRelatedTo) || filterPrimitivesIfContainsNonPrimitive(target as UnionType); + checkTypes = reducedTarget.flags & TypeFlags.Union ? (reducedTarget as UnionType).types : [reducedTarget]; + } + for (const prop of getPropertiesOfType(source)) { + if (shouldCheckAsExcessProperty(prop, source.symbol) && !isIgnoredJsxProperty(source, prop)) { + if (!isKnownProperty(reducedTarget, prop.escapedName, isComparingJsxAttributes)) { + if (reportErrors) { + // Report error in terms of object types in the target as those are the only ones + // we check in isKnownProperty. + const errorTarget = filterType(reducedTarget, isExcessPropertyCheckTarget); + // We know *exactly* where things went wrong when comparing the types. + // Use this property as the error node as this will be more helpful in + // reasoning about what went wrong. + if (!errorNode) return Debug.fail(); + if (isJsxAttributes(errorNode) || isJsxOpeningLikeElement(errorNode) || isJsxOpeningLikeElement(errorNode.parent)) { + // JsxAttributes has an object-literal flag and undergo same type-assignablity check as normal object-literal. + // However, using an object-literal error message will be very confusing to the users so we give different a message. + if (prop.valueDeclaration && isJsxAttribute(prop.valueDeclaration) && getSourceFileOfNode(errorNode) === getSourceFileOfNode(prop.valueDeclaration.name)) { + // Note that extraneous children (as in `extra`) don't pass this check, + // since `children` is a SyntaxKind.PropertySignature instead of a SyntaxKind.JsxAttribute. + errorNode = prop.valueDeclaration.name; + } + const propName = symbolToString(prop); + const suggestionSymbol = getSuggestedSymbolForNonexistentJSXAttribute(propName, errorTarget); + const suggestion = suggestionSymbol ? symbolToString(suggestionSymbol) : undefined; + if (suggestion) { + reportError(Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2, propName, typeToString(errorTarget), suggestion); + } + else { + reportError(Diagnostics.Property_0_does_not_exist_on_type_1, propName, typeToString(errorTarget)); + } + } + else { + // use the property's value declaration if the property is assigned inside the literal itself + const objectLiteralDeclaration = source.symbol?.declarations && firstOrUndefined(source.symbol.declarations); + let suggestion: string | undefined; + if (prop.valueDeclaration && findAncestor(prop.valueDeclaration, d => d === objectLiteralDeclaration) && getSourceFileOfNode(objectLiteralDeclaration) === getSourceFileOfNode(errorNode)) { + const propDeclaration = prop.valueDeclaration as ObjectLiteralElementLike; + Debug.assertNode(propDeclaration, isObjectLiteralElementLike); + + const name = propDeclaration.name!; + errorNode = name; + + if (isIdentifier(name)) { + suggestion = getSuggestionForNonexistentProperty(name, errorTarget); + } + } + if (suggestion !== undefined) { + reportParentSkippedError(Diagnostics.Object_literal_may_only_specify_known_properties_but_0_does_not_exist_in_type_1_Did_you_mean_to_write_2, symbolToString(prop), typeToString(errorTarget), suggestion); + } + else { + reportParentSkippedError(Diagnostics.Object_literal_may_only_specify_known_properties_and_0_does_not_exist_in_type_1, symbolToString(prop), typeToString(errorTarget)); + } + } + } + return true; + } + if (checkTypes && !isRelatedTo(getTypeOfSymbol(prop), getTypeOfPropertyInTypes(checkTypes, prop.escapedName), RecursionFlags.Both, reportErrors)) { + if (reportErrors) { + reportIncompatibleError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(prop)); + } + return true; + } + } + } + return false; + } + + function shouldCheckAsExcessProperty(prop: Symbol, container: Symbol) { + return prop.valueDeclaration && container.valueDeclaration && prop.valueDeclaration.parent === container.valueDeclaration; + } + + function unionOrIntersectionRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + // Note that these checks are specifically ordered to produce correct results. In particular, + // we need to deconstruct unions before intersections (because unions are always at the top), + // and we need to handle "each" relations before "some" relations for the same kind of type. + if (source.flags & TypeFlags.Union) { + if (target.flags & TypeFlags.Union) { + // Intersections of union types are normalized into unions of intersection types, and such normalized + // unions can get very large and expensive to relate. The following fast path checks if the source union + // originated in an intersection. If so, and if that intersection contains the target type, then we know + // the result to be true (for any two types A and B, A & B is related to both A and B). + const sourceOrigin = (source as UnionType).origin; + if (sourceOrigin && sourceOrigin.flags & TypeFlags.Intersection && target.aliasSymbol && contains((sourceOrigin as IntersectionType).types, target)) { + return Ternary.True; + } + // Similarly, in unions of unions the we preserve the original list of unions. This original list is often + // much shorter than the normalized result, so we scan it in the following fast path. + const targetOrigin = (target as UnionType).origin; + if (targetOrigin && targetOrigin.flags & TypeFlags.Union && source.aliasSymbol && contains((targetOrigin as UnionType).types, source)) { + return Ternary.True; + } + } + return relation === comparableRelation ? + someTypeRelatedToType(source as UnionType, target, reportErrors && !(source.flags & TypeFlags.Primitive), intersectionState) : + eachTypeRelatedToType(source as UnionType, target, reportErrors && !(source.flags & TypeFlags.Primitive), intersectionState); + } + if (target.flags & TypeFlags.Union) { + return typeRelatedToSomeType(getRegularTypeOfObjectLiteral(source), target as UnionType, reportErrors && !(source.flags & TypeFlags.Primitive) && !(target.flags & TypeFlags.Primitive), intersectionState); + } + if (target.flags & TypeFlags.Intersection) { + return typeRelatedToEachType(source, target as IntersectionType, reportErrors, IntersectionState.Target); + } + // Source is an intersection. For the comparable relation, if the target is a primitive type we hoist the + // constraints of all non-primitive types in the source into a new intersection. We do this because the + // intersection may further constrain the constraints of the non-primitive types. For example, given a type + // parameter 'T extends 1 | 2', the intersection 'T & 1' should be reduced to '1' such that it doesn't + // appear to be comparable to '2'. + if (relation === comparableRelation && target.flags & TypeFlags.Primitive) { + const constraints = sameMap((source as IntersectionType).types, t => t.flags & TypeFlags.Instantiable ? getBaseConstraintOfType(t) || unknownType : t); + if (constraints !== (source as IntersectionType).types) { + source = getIntersectionType(constraints); + if (source.flags & TypeFlags.Never) { + return Ternary.False; + } + if (!(source.flags & TypeFlags.Intersection)) { + return isRelatedTo(source, target, RecursionFlags.Source, /*reportErrors*/ false) || + isRelatedTo(target, source, RecursionFlags.Source, /*reportErrors*/ false); + } + } + } + // Check to see if any constituents of the intersection are immediately related to the target. + // Don't report errors though. Elaborating on whether a source constituent is related to the target is + // not actually useful and leads to some confusing error messages. Instead, we rely on the caller + // checking whether the full intersection viewed as an object is related to the target. + return someTypeRelatedToType(source as IntersectionType, target, /*reportErrors*/ false, IntersectionState.Source); + } + + function eachTypeRelatedToSomeType(source: UnionOrIntersectionType, target: UnionOrIntersectionType): Ternary { + let result = Ternary.True; + const sourceTypes = source.types; + for (const sourceType of sourceTypes) { + const related = typeRelatedToSomeType(sourceType, target, /*reportErrors*/ false, IntersectionState.None); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function typeRelatedToSomeType(source: Type, target: UnionOrIntersectionType, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const targetTypes = target.types; + if (target.flags & TypeFlags.Union) { + if (containsType(targetTypes, source)) { + return Ternary.True; + } + if ( + relation !== comparableRelation && getObjectFlags(target) & ObjectFlags.PrimitiveUnion && !(source.flags & TypeFlags.EnumLiteral) && ( + source.flags & (TypeFlags.StringLiteral | TypeFlags.BooleanLiteral | TypeFlags.BigIntLiteral) || + (relation === subtypeRelation || relation === strictSubtypeRelation) && source.flags & TypeFlags.NumberLiteral + ) + ) { + // When relating a literal type to a union of primitive types, we know the relation is false unless + // the union contains the base primitive type or the literal type in one of its fresh/regular forms. + // We exclude numeric literals for non-subtype relations because numeric literals are assignable to + // numeric enum literals with the same value. Similarly, we exclude enum literal types because + // identically named enum types are related (see isEnumTypeRelatedTo). We exclude the comparable + // relation in entirety because it needs to be checked in both directions. + const alternateForm = source === (source as StringLiteralType).regularType ? (source as StringLiteralType).freshType : (source as StringLiteralType).regularType; + const primitive = source.flags & TypeFlags.StringLiteral ? stringType : + source.flags & TypeFlags.NumberLiteral ? numberType : + source.flags & TypeFlags.BigIntLiteral ? bigintType : + undefined; + return primitive && containsType(targetTypes, primitive) || alternateForm && containsType(targetTypes, alternateForm) ? Ternary.True : Ternary.False; + } + const match = getMatchingUnionConstituentForType(target as UnionType, source); + if (match) { + const related = isRelatedTo(source, match, RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (related) { + return related; + } + } + } + for (const type of targetTypes) { + const related = isRelatedTo(source, type, RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (related) { + return related; + } + } + if (reportErrors) { + // Elaborate only if we can find a best matching type in the target union + const bestMatchingType = getBestMatchingType(source, target, isRelatedTo); + if (bestMatchingType) { + isRelatedTo(source, bestMatchingType, RecursionFlags.Target, /*reportErrors*/ true, /*headMessage*/ undefined, intersectionState); + } + } + return Ternary.False; + } + + function typeRelatedToEachType(source: Type, target: IntersectionType, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + let result = Ternary.True; + const targetTypes = target.types; + for (const targetType of targetTypes) { + const related = isRelatedTo(source, targetType, RecursionFlags.Target, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function someTypeRelatedToType(source: UnionOrIntersectionType, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const sourceTypes = source.types; + if (source.flags & TypeFlags.Union && containsType(sourceTypes, target)) { + return Ternary.True; + } + const len = sourceTypes.length; + for (let i = 0; i < len; i++) { + const related = isRelatedTo(sourceTypes[i], target, RecursionFlags.Source, reportErrors && i === len - 1, /*headMessage*/ undefined, intersectionState); + if (related) { + return related; + } + } + return Ternary.False; + } + + function getUndefinedStrippedTargetIfNeeded(source: Type, target: Type) { + if ( + source.flags & TypeFlags.Union && target.flags & TypeFlags.Union && + !((source as UnionType).types[0].flags & TypeFlags.Undefined) && (target as UnionType).types[0].flags & TypeFlags.Undefined + ) { + return extractTypesOfKind(target, ~TypeFlags.Undefined); + } + return target; + } + + function eachTypeRelatedToType(source: UnionOrIntersectionType, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + let result = Ternary.True; + const sourceTypes = source.types; + // We strip `undefined` from the target if the `source` trivially doesn't contain it for our correspondence-checking fastpath + // since `undefined` is frequently added by optionality and would otherwise spoil a potentially useful correspondence + const undefinedStrippedTarget = getUndefinedStrippedTargetIfNeeded(source, target as UnionType); + for (let i = 0; i < sourceTypes.length; i++) { + const sourceType = sourceTypes[i]; + if (undefinedStrippedTarget.flags & TypeFlags.Union && sourceTypes.length >= (undefinedStrippedTarget as UnionType).types.length && sourceTypes.length % (undefinedStrippedTarget as UnionType).types.length === 0) { + // many unions are mappings of one another; in such cases, simply comparing members at the same index can shortcut the comparison + // such unions will have identical lengths, and their corresponding elements will match up. Another common scenario is where a large + // union has a union of objects intersected with it. In such cases, if the input was, eg `("a" | "b" | "c") & (string | boolean | {} | {whatever})`, + // the result will have the structure `"a" | "b" | "c" | "a" & {} | "b" & {} | "c" & {} | "a" & {whatever} | "b" & {whatever} | "c" & {whatever}` + // - the resulting union has a length which is a multiple of the original union, and the elements correspond modulo the length of the original union + const related = isRelatedTo(sourceType, (undefinedStrippedTarget as UnionType).types[i % (undefinedStrippedTarget as UnionType).types.length], RecursionFlags.Both, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (related) { + result &= related; + continue; + } + } + const related = isRelatedTo(sourceType, target, RecursionFlags.Source, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function typeArgumentsRelatedTo(sources: readonly Type[] = emptyArray, targets: readonly Type[] = emptyArray, variances: readonly VarianceFlags[] = emptyArray, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + if (sources.length !== targets.length && relation === identityRelation) { + return Ternary.False; + } + const length = sources.length <= targets.length ? sources.length : targets.length; + let result = Ternary.True; + for (let i = 0; i < length; i++) { + // When variance information isn't available we default to covariance. This happens + // in the process of computing variance information for recursive types and when + // comparing 'this' type arguments. + const varianceFlags = i < variances.length ? variances[i] : VarianceFlags.Covariant; + const variance = varianceFlags & VarianceFlags.VarianceMask; + // We ignore arguments for independent type parameters (because they're never witnessed). + if (variance !== VarianceFlags.Independent) { + const s = sources[i]; + const t = targets[i]; + let related = Ternary.True; + if (varianceFlags & VarianceFlags.Unmeasurable) { + // Even an `Unmeasurable` variance works out without a structural check if the source and target are _identical_. + // We can't simply assume invariance, because `Unmeasurable` marks nonlinear relations, for example, a relation tained by + // the `-?` modifier in a mapped type (where, no matter how the inputs are related, the outputs still might not be) + related = relation === identityRelation ? isRelatedTo(s, t, RecursionFlags.Both, /*reportErrors*/ false) : compareTypesIdentical(s, t); + } + else if (variance === VarianceFlags.Covariant) { + related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + else if (variance === VarianceFlags.Contravariant) { + related = isRelatedTo(t, s, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + else if (variance === VarianceFlags.Bivariant) { + // In the bivariant case we first compare contravariantly without reporting + // errors. Then, if that doesn't succeed, we compare covariantly with error + // reporting. Thus, error elaboration will be based on the the covariant check, + // which is generally easier to reason about. + related = isRelatedTo(t, s, RecursionFlags.Both, /*reportErrors*/ false); + if (!related) { + related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + } + else { + // In the invariant case we first compare covariantly, and only when that + // succeeds do we proceed to compare contravariantly. Thus, error elaboration + // will typically be based on the covariant check. + related = isRelatedTo(s, t, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (related) { + related &= isRelatedTo(t, s, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + } + if (!related) { + return Ternary.False; + } + result &= related; + } + } + return result; + } + + // Determine if possibly recursive types are related. First, check if the result is already available in the global cache. + // Second, check if we have already started a comparison of the given two types in which case we assume the result to be true. + // Third, check if both types are part of deeply nested chains of generic type instantiations and if so assume the types are + // equal and infinitely expanding. Fourth, if we have reached a depth of 100 nested comparisons, assume we have runaway recursion + // and issue an error. Otherwise, actually compare the structure of the two types. + function recursiveTypeRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState, recursionFlags: RecursionFlags): Ternary { + if (overflow) { + return Ternary.False; + } + const id = getRelationKey(source, target, intersectionState, relation, /*ignoreConstraints*/ false); + const entry = relation.get(id); + if (entry !== undefined) { + if (reportErrors && entry & RelationComparisonResult.Failed && !(entry & RelationComparisonResult.Reported)) { + // We are elaborating errors and the cached result is an unreported failure. The result will be reported + // as a failure, and should be updated as a reported failure by the bottom of this function. + } + else { + if (outofbandVarianceMarkerHandler) { + // We're in the middle of variance checking - integrate any unmeasurable/unreliable flags from this cached component + const saved = entry & RelationComparisonResult.ReportsMask; + if (saved & RelationComparisonResult.ReportsUnmeasurable) { + instantiateType(source, reportUnmeasurableMapper); + } + if (saved & RelationComparisonResult.ReportsUnreliable) { + instantiateType(source, reportUnreliableMapper); + } + } + return entry & RelationComparisonResult.Succeeded ? Ternary.True : Ternary.False; + } + } + if (relationCount <= 0) { + overflow = true; + return Ternary.False; + } + if (!maybeKeys) { + maybeKeys = []; + maybeKeysSet = new Set(); + sourceStack = []; + targetStack = []; + } + else { + // If source and target are already being compared, consider them related with assumptions + if (maybeKeysSet.has(id)) { + return Ternary.Maybe; + } + + // A key that starts with "*" is an indication that we have type references that reference constrained + // type parameters. For such keys we also check against the key we would have gotten if all type parameters + // were unconstrained. + const broadestEquivalentId = id.startsWith("*") ? getRelationKey(source, target, intersectionState, relation, /*ignoreConstraints*/ true) : undefined; + if (broadestEquivalentId && maybeKeysSet.has(broadestEquivalentId)) { + return Ternary.Maybe; + } + + if (sourceDepth === 100 || targetDepth === 100) { + overflow = true; + return Ternary.False; + } + } + const maybeStart = maybeCount; + maybeKeys[maybeCount] = id; + maybeKeysSet.add(id); + maybeCount++; + const saveExpandingFlags = expandingFlags; + if (recursionFlags & RecursionFlags.Source) { + sourceStack[sourceDepth] = source; + sourceDepth++; + if (!(expandingFlags & ExpandingFlags.Source) && isDeeplyNestedType(source, sourceStack, sourceDepth)) expandingFlags |= ExpandingFlags.Source; + } + if (recursionFlags & RecursionFlags.Target) { + targetStack[targetDepth] = target; + targetDepth++; + if (!(expandingFlags & ExpandingFlags.Target) && isDeeplyNestedType(target, targetStack, targetDepth)) expandingFlags |= ExpandingFlags.Target; + } + let originalHandler: typeof outofbandVarianceMarkerHandler; + let propagatingVarianceFlags = 0 as RelationComparisonResult; + if (outofbandVarianceMarkerHandler) { + originalHandler = outofbandVarianceMarkerHandler; + outofbandVarianceMarkerHandler = onlyUnreliable => { + propagatingVarianceFlags |= onlyUnreliable ? RelationComparisonResult.ReportsUnreliable : RelationComparisonResult.ReportsUnmeasurable; + return originalHandler!(onlyUnreliable); + }; + } + + let result: Ternary; + if (expandingFlags === ExpandingFlags.Both) { + tracing?.instant(tracing.Phase.CheckTypes, "recursiveTypeRelatedTo_DepthLimit", { + sourceId: source.id, + sourceIdStack: sourceStack.map(t => t.id), + targetId: target.id, + targetIdStack: targetStack.map(t => t.id), + depth: sourceDepth, + targetDepth, + }); + result = Ternary.Maybe; + } + else { + tracing?.push(tracing.Phase.CheckTypes, "structuredTypeRelatedTo", { sourceId: source.id, targetId: target.id }); + result = structuredTypeRelatedTo(source, target, reportErrors, intersectionState); + tracing?.pop(); + } + + if (outofbandVarianceMarkerHandler) { + outofbandVarianceMarkerHandler = originalHandler; + } + if (recursionFlags & RecursionFlags.Source) { + sourceDepth--; + } + if (recursionFlags & RecursionFlags.Target) { + targetDepth--; + } + expandingFlags = saveExpandingFlags; + if (result) { + if (result === Ternary.True || (sourceDepth === 0 && targetDepth === 0)) { + if (result === Ternary.True || result === Ternary.Maybe) { + // If result is definitely true, record all maybe keys as having succeeded. Also, record Ternary.Maybe + // results as having succeeded once we reach depth 0, but never record Ternary.Unknown results. + resetMaybeStack(/*markAllAsSucceeded*/ true); + } + else { + resetMaybeStack(/*markAllAsSucceeded*/ false); + } + } + // Note: it's intentional that we don't reset in the else case; + // we leave them on the stack such that when we hit depth zero + // above, we can report all of them as successful. + } + else { + // A false result goes straight into global cache (when something is false under + // assumptions it will also be false without assumptions) + relation.set(id, (reportErrors ? RelationComparisonResult.Reported : 0) | RelationComparisonResult.Failed | propagatingVarianceFlags); + relationCount--; + resetMaybeStack(/*markAllAsSucceeded*/ false); + } + return result; + + function resetMaybeStack(markAllAsSucceeded: boolean) { + for (let i = maybeStart; i < maybeCount; i++) { + maybeKeysSet.delete(maybeKeys[i]); + if (markAllAsSucceeded) { + relation.set(maybeKeys[i], RelationComparisonResult.Succeeded | propagatingVarianceFlags); + relationCount--; + } + } + maybeCount = maybeStart; + } + } + + function structuredTypeRelatedTo(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const saveErrorInfo = captureErrorCalculationState(); + let result = structuredTypeRelatedToWorker(source, target, reportErrors, intersectionState, saveErrorInfo); + if (relation !== identityRelation) { + // The combined constraint of an intersection type is the intersection of the constraints of + // the constituents. When an intersection type contains instantiable types with union type + // constraints, there are situations where we need to examine the combined constraint. One is + // when the target is a union type. Another is when the intersection contains types belonging + // to one of the disjoint domains. For example, given type variables T and U, each with the + // constraint 'string | number', the combined constraint of 'T & U' is 'string | number' and + // we need to check this constraint against a union on the target side. Also, given a type + // variable V constrained to 'string | number', 'V & number' has a combined constraint of + // 'string & number | number & number' which reduces to just 'number'. + // This also handles type parameters, as a type parameter with a union constraint compared against a union + // needs to have its constraint hoisted into an intersection with said type parameter, this way + // the type param can be compared with itself in the target (with the influence of its constraint to match other parts) + // For example, if `T extends 1 | 2` and `U extends 2 | 3` and we compare `T & U` to `T & U & (1 | 2 | 3)` + if (!result && (source.flags & TypeFlags.Intersection || source.flags & TypeFlags.TypeParameter && target.flags & TypeFlags.Union)) { + const constraint = getEffectiveConstraintOfIntersection(source.flags & TypeFlags.Intersection ? (source as IntersectionType).types : [source], !!(target.flags & TypeFlags.Union)); + if (constraint && everyType(constraint, c => c !== source)) { // Skip comparison if expansion contains the source itself + // TODO: Stack errors so we get a pyramid for the "normal" comparison above, _and_ a second for this + result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + } + } + // When the target is an intersection we need an extra property check in order to detect nested excess + // properties and nested weak types. The following are motivating examples that all should be errors, but + // aren't without this extra property check: + // + // let obj: { a: { x: string } } & { c: number } = { a: { x: 'hello', y: 2 }, c: 5 }; // Nested excess property + // + // declare let wrong: { a: { y: string } }; + // let weak: { a?: { x?: number } } & { c?: string } = wrong; // Nested weak object type + // + if ( + result && !(intersectionState & IntersectionState.Target) && target.flags & TypeFlags.Intersection && + !isGenericObjectType(target) && source.flags & (TypeFlags.Object | TypeFlags.Intersection) + ) { + result &= propertiesRelatedTo(source, target, reportErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ false, IntersectionState.None); + if (result && isObjectLiteralType(source) && getObjectFlags(source) & ObjectFlags.FreshLiteral) { + result &= indexSignaturesRelatedTo(source, target, /*sourceIsPrimitive*/ false, reportErrors, IntersectionState.None); + } + } + // When the source is an intersection we need an extra check of any optional properties in the target to + // detect possible mismatched property types. For example: + // + // function foo(x: { a?: string }, y: T & { a: boolean }) { + // x = y; // Mismatched property in source intersection + // } + // + else if ( + result && isNonGenericObjectType(target) && !isArrayOrTupleType(target) && + source.flags & TypeFlags.Intersection && getApparentType(source).flags & TypeFlags.StructuredType && + !some((source as IntersectionType).types, t => t === target || !!(getObjectFlags(t) & ObjectFlags.NonInferrableType)) + ) { + result &= propertiesRelatedTo(source, target, reportErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ true, intersectionState); + } + } + if (result) { + resetErrorInfo(saveErrorInfo); + } + return result; + } + + function getApparentMappedTypeKeys(nameType: Type, targetType: MappedType) { + const modifiersType = getApparentType(getModifiersTypeFromMappedType(targetType)); + const mappedKeys: Type[] = []; + forEachMappedTypePropertyKeyTypeAndIndexSignatureKeyType( + modifiersType, + TypeFlags.StringOrNumberLiteralOrUnique, + /*stringsOnly*/ false, + t => void mappedKeys.push(instantiateType(nameType, appendTypeMapping(targetType.mapper, getTypeParameterFromMappedType(targetType), t))), + ); + return getUnionType(mappedKeys); + } + + function structuredTypeRelatedToWorker(source: Type, target: Type, reportErrors: boolean, intersectionState: IntersectionState, saveErrorInfo: ReturnType): Ternary { + let result: Ternary; + let originalErrorInfo: DiagnosticMessageChain | undefined; + let varianceCheckFailed = false; + let sourceFlags = source.flags; + const targetFlags = target.flags; + if (relation === identityRelation) { + // We've already checked that source.flags and target.flags are identical + if (sourceFlags & TypeFlags.UnionOrIntersection) { + let result = eachTypeRelatedToSomeType(source as UnionOrIntersectionType, target as UnionOrIntersectionType); + if (result) { + result &= eachTypeRelatedToSomeType(target as UnionOrIntersectionType, source as UnionOrIntersectionType); + } + return result; + } + if (sourceFlags & TypeFlags.Index) { + return isRelatedTo((source as IndexType).type, (target as IndexType).type, RecursionFlags.Both, /*reportErrors*/ false); + } + if (sourceFlags & TypeFlags.IndexedAccess) { + if (result = isRelatedTo((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType, RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + } + if (sourceFlags & TypeFlags.Conditional) { + if ((source as ConditionalType).root.isDistributive === (target as ConditionalType).root.isDistributive) { + if (result = isRelatedTo((source as ConditionalType).checkType, (target as ConditionalType).checkType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo((source as ConditionalType).extendsType, (target as ConditionalType).extendsType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo(getTrueTypeFromConditionalType(source as ConditionalType), getTrueTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + } + } + } + } + if (sourceFlags & TypeFlags.Substitution) { + if (result = isRelatedTo((source as SubstitutionType).baseType, (target as SubstitutionType).baseType, RecursionFlags.Both, /*reportErrors*/ false)) { + if (result &= isRelatedTo((source as SubstitutionType).constraint, (target as SubstitutionType).constraint, RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + } + if (!(sourceFlags & TypeFlags.Object)) { + return Ternary.False; + } + } + else if (sourceFlags & TypeFlags.UnionOrIntersection || targetFlags & TypeFlags.UnionOrIntersection) { + if (result = unionOrIntersectionRelatedTo(source, target, reportErrors, intersectionState)) { + return result; + } + // The ordered decomposition above doesn't handle all cases. Specifically, we also need to handle: + // Source is instantiable (e.g. source has union or intersection constraint). + // Source is an object, target is a union (e.g. { a, b: boolean } <=> { a, b: true } | { a, b: false }). + // Source is an intersection, target is an object (e.g. { a } & { b } <=> { a, b }). + // Source is an intersection, target is a union (e.g. { a } & { b: boolean } <=> { a, b: true } | { a, b: false }). + // Source is an intersection, target instantiable (e.g. string & { tag } <=> T["a"] constrained to string & { tag }). + if ( + !(sourceFlags & TypeFlags.Instantiable || + sourceFlags & TypeFlags.Object && targetFlags & TypeFlags.Union || + sourceFlags & TypeFlags.Intersection && targetFlags & (TypeFlags.Object | TypeFlags.Union | TypeFlags.Instantiable)) + ) { + return Ternary.False; + } + } + + // We limit alias variance probing to only object and conditional types since their alias behavior + // is more predictable than other, interned types, which may or may not have an alias depending on + // the order in which things were checked. + if ( + sourceFlags & (TypeFlags.Object | TypeFlags.Conditional) && source.aliasSymbol && source.aliasTypeArguments && + source.aliasSymbol === target.aliasSymbol && !(isMarkerType(source) || isMarkerType(target)) + ) { + const variances = getAliasVariances(source.aliasSymbol); + if (variances === emptyArray) { + return Ternary.Unknown; + } + const params = getSymbolLinks(source.aliasSymbol).typeParameters!; + const minParams = getMinTypeArgumentCount(params); + const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + const varianceResult = relateVariances(sourceTypes, targetTypes, variances, intersectionState); + if (varianceResult !== undefined) { + return varianceResult; + } + } + + // For a generic type T and a type U that is assignable to T, [...U] is assignable to T, U is assignable to readonly [...T], + // and U is assignable to [...T] when U is constrained to a mutable array or tuple type. + if ( + isSingleElementGenericTupleType(source) && !source.target.readonly && (result = isRelatedTo(getTypeArguments(source)[0], target, RecursionFlags.Source)) || + isSingleElementGenericTupleType(target) && (target.target.readonly || isMutableArrayOrTuple(getBaseConstraintOfType(source) || source)) && (result = isRelatedTo(source, getTypeArguments(target)[0], RecursionFlags.Target)) + ) { + return result; + } + + if (targetFlags & TypeFlags.TypeParameter) { + // A source type { [P in Q]: X } is related to a target type T if keyof T is related to Q and X is related to T[Q]. + if (getObjectFlags(source) & ObjectFlags.Mapped && !(source as MappedType).declaration.nameType && isRelatedTo(getIndexType(target), getConstraintTypeFromMappedType(source as MappedType), RecursionFlags.Both)) { + if (!(getMappedTypeModifiers(source as MappedType) & MappedTypeModifiers.IncludeOptional)) { + const templateType = getTemplateTypeFromMappedType(source as MappedType); + const indexedAccessType = getIndexedAccessType(target, getTypeParameterFromMappedType(source as MappedType)); + if (result = isRelatedTo(templateType, indexedAccessType, RecursionFlags.Both, reportErrors)) { + return result; + } + } + } + if (relation === comparableRelation && sourceFlags & TypeFlags.TypeParameter) { + // This is a carve-out in comparability to essentially forbid comparing a type parameter + // with another type parameter unless one extends the other. (Remember: comparability is mostly bidirectional!) + let constraint = getConstraintOfTypeParameter(source); + if (constraint) { + while (constraint && someType(constraint, c => !!(c.flags & TypeFlags.TypeParameter))) { + if (result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false)) { + return result; + } + constraint = getConstraintOfTypeParameter(constraint); + } + } + return Ternary.False; + } + } + else if (targetFlags & TypeFlags.Index) { + const targetType = (target as IndexType).type; + // A keyof S is related to a keyof T if T is related to S. + if (sourceFlags & TypeFlags.Index) { + if (result = isRelatedTo(targetType, (source as IndexType).type, RecursionFlags.Both, /*reportErrors*/ false)) { + return result; + } + } + if (isTupleType(targetType)) { + // An index type can have a tuple type target when the tuple type contains variadic elements. + // Check if the source is related to the known keys of the tuple type. + if (result = isRelatedTo(source, getKnownKeysOfTupleType(targetType), RecursionFlags.Target, reportErrors)) { + return result; + } + } + else { + // A type S is assignable to keyof T if S is assignable to keyof C, where C is the + // simplified form of T or, if T doesn't simplify, the constraint of T. + const constraint = getSimplifiedTypeOrConstraint(targetType); + if (constraint) { + // We require Ternary.True here such that circular constraints don't cause + // false positives. For example, given 'T extends { [K in keyof T]: string }', + // 'keyof T' has itself as its constraint and produces a Ternary.Maybe when + // related to other types. + if (isRelatedTo(source, getIndexType(constraint, (target as IndexType).indexFlags | IndexFlags.NoReducibleCheck), RecursionFlags.Target, reportErrors) === Ternary.True) { + return Ternary.True; + } + } + else if (isGenericMappedType(targetType)) { + // generic mapped types that don't simplify or have a constraint still have a very simple set of keys we can compare against + // - their nameType or constraintType. + // In many ways, this comparison is a deferred version of what `getIndexTypeForMappedType` does to actually resolve the keys for _non_-generic types + + const nameType = getNameTypeFromMappedType(targetType); + const constraintType = getConstraintTypeFromMappedType(targetType); + let targetKeys; + if (nameType && isMappedTypeWithKeyofConstraintDeclaration(targetType)) { + // we need to get the apparent mappings and union them with the generic mappings, since some properties may be + // missing from the `constraintType` which will otherwise be mapped in the object + const mappedKeys = getApparentMappedTypeKeys(nameType, targetType); + // We still need to include the non-apparent (and thus still generic) keys in the target side of the comparison (in case they're in the source side) + targetKeys = getUnionType([mappedKeys, nameType]); + } + else { + targetKeys = nameType || constraintType; + } + if (isRelatedTo(source, targetKeys, RecursionFlags.Target, reportErrors) === Ternary.True) { + return Ternary.True; + } + } + } + } + else if (targetFlags & TypeFlags.IndexedAccess) { + if (sourceFlags & TypeFlags.IndexedAccess) { + // Relate components directly before falling back to constraint relationships + // A type S[K] is related to a type T[J] if S is related to T and K is related to J. + if (result = isRelatedTo((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType, RecursionFlags.Both, reportErrors)) { + result &= isRelatedTo((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType, RecursionFlags.Both, reportErrors); + } + if (result) { + return result; + } + if (reportErrors) { + originalErrorInfo = errorInfo; + } + } + // A type S is related to a type T[K] if S is related to C, where C is the base + // constraint of T[K] for writing. + if (relation === assignableRelation || relation === comparableRelation) { + const objectType = (target as IndexedAccessType).objectType; + const indexType = (target as IndexedAccessType).indexType; + const baseObjectType = getBaseConstraintOfType(objectType) || objectType; + const baseIndexType = getBaseConstraintOfType(indexType) || indexType; + if (!isGenericObjectType(baseObjectType) && !isGenericIndexType(baseIndexType)) { + const accessFlags = AccessFlags.Writing | (baseObjectType !== objectType ? AccessFlags.NoIndexSignatures : 0); + const constraint = getIndexedAccessTypeOrUndefined(baseObjectType, baseIndexType, accessFlags); + if (constraint) { + if (reportErrors && originalErrorInfo) { + // create a new chain for the constraint error + resetErrorInfo(saveErrorInfo); + } + if (result = isRelatedTo(source, constraint, RecursionFlags.Target, reportErrors, /*headMessage*/ undefined, intersectionState)) { + return result; + } + // prefer the shorter chain of the constraint comparison chain, and the direct comparison chain + if (reportErrors && originalErrorInfo && errorInfo) { + errorInfo = countMessageChainBreadth([originalErrorInfo]) <= countMessageChainBreadth([errorInfo]) ? originalErrorInfo : errorInfo; + } + } + } + } + if (reportErrors) { + originalErrorInfo = undefined; + } + } + else if (isGenericMappedType(target) && relation !== identityRelation) { + // Check if source type `S` is related to target type `{ [P in Q]: T }` or `{ [P in Q as R]: T}`. + const keysRemapped = !!target.declaration.nameType; + const templateType = getTemplateTypeFromMappedType(target); + const modifiers = getMappedTypeModifiers(target); + if (!(modifiers & MappedTypeModifiers.ExcludeOptional)) { + // If the mapped type has shape `{ [P in Q]: T[P] }`, + // source `S` is related to target if `T` = `S`, i.e. `S` is related to `{ [P in Q]: S[P] }`. + if ( + !keysRemapped && templateType.flags & TypeFlags.IndexedAccess && (templateType as IndexedAccessType).objectType === source && + (templateType as IndexedAccessType).indexType === getTypeParameterFromMappedType(target) + ) { + return Ternary.True; + } + if (!isGenericMappedType(source)) { + // If target has shape `{ [P in Q as R]: T}`, then its keys have type `R`. + // If target has shape `{ [P in Q]: T }`, then its keys have type `Q`. + const targetKeys = keysRemapped ? getNameTypeFromMappedType(target)! : getConstraintTypeFromMappedType(target); + // Type of the keys of source type `S`, i.e. `keyof S`. + const sourceKeys = getIndexType(source, IndexFlags.NoIndexSignatures); + const includeOptional = modifiers & MappedTypeModifiers.IncludeOptional; + const filteredByApplicability = includeOptional ? intersectTypes(targetKeys, sourceKeys) : undefined; + // A source type `S` is related to a target type `{ [P in Q]: T }` if `Q` is related to `keyof S` and `S[Q]` is related to `T`. + // A source type `S` is related to a target type `{ [P in Q as R]: T }` if `R` is related to `keyof S` and `S[R]` is related to `T. + // A source type `S` is related to a target type `{ [P in Q]?: T }` if some constituent `Q'` of `Q` is related to `keyof S` and `S[Q']` is related to `T`. + // A source type `S` is related to a target type `{ [P in Q as R]?: T }` if some constituent `R'` of `R` is related to `keyof S` and `S[R']` is related to `T`. + if ( + includeOptional + ? !(filteredByApplicability!.flags & TypeFlags.Never) + : isRelatedTo(targetKeys, sourceKeys, RecursionFlags.Both) + ) { + const templateType = getTemplateTypeFromMappedType(target); + const typeParameter = getTypeParameterFromMappedType(target); + + // Fastpath: When the template type has the form `Obj[P]` where `P` is the mapped type parameter, directly compare source `S` with `Obj` + // to avoid creating the (potentially very large) number of new intermediate types made by manufacturing `S[P]`. + const nonNullComponent = extractTypesOfKind(templateType, ~TypeFlags.Nullable); + if (!keysRemapped && nonNullComponent.flags & TypeFlags.IndexedAccess && (nonNullComponent as IndexedAccessType).indexType === typeParameter) { + if (result = isRelatedTo(source, (nonNullComponent as IndexedAccessType).objectType, RecursionFlags.Target, reportErrors)) { + return result; + } + } + else { + // We need to compare the type of a property on the source type `S` to the type of the same property on the target type, + // so we need to construct an indexing type representing a property, and then use indexing type to index the source type for comparison. + + // If the target type has shape `{ [P in Q]: T }`, then a property of the target has type `P`. + // If the target type has shape `{ [P in Q]?: T }`, then a property of the target has type `P`, + // but the property is optional, so we only want to compare properties `P` that are common between `keyof S` and `Q`. + // If the target type has shape `{ [P in Q as R]: T }`, then a property of the target has type `R`. + // If the target type has shape `{ [P in Q as R]?: T }`, then a property of the target has type `R`, + // but the property is optional, so we only want to compare properties `R` that are common between `keyof S` and `R`. + const indexingType = keysRemapped + ? (filteredByApplicability || targetKeys) + : filteredByApplicability + ? getIntersectionType([filteredByApplicability, typeParameter]) + : typeParameter; + const indexedAccessType = getIndexedAccessType(source, indexingType); + // Compare `S[indexingType]` to `T`, where `T` is the type of a property of the target type. + if (result = isRelatedTo(indexedAccessType, templateType, RecursionFlags.Both, reportErrors)) { + return result; + } + } + } + originalErrorInfo = errorInfo; + resetErrorInfo(saveErrorInfo); + } + } + } + else if (targetFlags & TypeFlags.Conditional) { + // If we reach 10 levels of nesting for the same conditional type, assume it is an infinitely expanding recursive + // conditional type and bail out with a Ternary.Maybe result. + if (isDeeplyNestedType(target, targetStack, targetDepth, 10)) { + return Ternary.Maybe; + } + const c = target as ConditionalType; + // We check for a relationship to a conditional type target only when the conditional type has no + // 'infer' positions, is not distributive or is distributive but doesn't reference the check type + // parameter in either of the result types, and the source isn't an instantiation of the same + // conditional type (as happens when computing variance). + if (!c.root.inferTypeParameters && !isDistributionDependent(c.root) && !(source.flags & TypeFlags.Conditional && (source as ConditionalType).root === c.root)) { + // Check if the conditional is always true or always false but still deferred for distribution purposes. + const skipTrue = !isTypeAssignableTo(getPermissiveInstantiation(c.checkType), getPermissiveInstantiation(c.extendsType)); + const skipFalse = !skipTrue && isTypeAssignableTo(getRestrictiveInstantiation(c.checkType), getRestrictiveInstantiation(c.extendsType)); + // TODO: Find a nice way to include potential conditional type breakdowns in error output, if they seem good (they usually don't) + if (result = skipTrue ? Ternary.True : isRelatedTo(source, getTrueTypeFromConditionalType(c), RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState)) { + result &= skipFalse ? Ternary.True : isRelatedTo(source, getFalseTypeFromConditionalType(c), RecursionFlags.Target, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState); + if (result) { + return result; + } + } + } + } + else if (targetFlags & TypeFlags.TemplateLiteral) { + if (sourceFlags & TypeFlags.TemplateLiteral) { + if (relation === comparableRelation) { + return templateLiteralTypesDefinitelyUnrelated(source as TemplateLiteralType, target as TemplateLiteralType) ? Ternary.False : Ternary.True; + } + // Report unreliable variance for type variables referenced in template literal type placeholders. + // For example, `foo-${number}` is related to `foo-${string}` even though number isn't related to string. + instantiateType(source, reportUnreliableMapper); + } + if (isTypeMatchedByTemplateLiteralType(source, target as TemplateLiteralType)) { + return Ternary.True; + } + } + else if (target.flags & TypeFlags.StringMapping) { + if (!(source.flags & TypeFlags.StringMapping)) { + if (isMemberOfStringMapping(source, target)) { + return Ternary.True; + } + } + } + + if (sourceFlags & TypeFlags.TypeVariable) { + // IndexedAccess comparisons are handled above in the `targetFlags & TypeFlage.IndexedAccess` branch + if (!(sourceFlags & TypeFlags.IndexedAccess && targetFlags & TypeFlags.IndexedAccess)) { + const constraint = getConstraintOfType(source as TypeVariable) || unknownType; + // hi-speed no-this-instantiation check (less accurate, but avoids costly `this`-instantiation when the constraint will suffice), see #28231 for report on why this is needed + if (result = isRelatedTo(constraint, target, RecursionFlags.Source, /*reportErrors*/ false, /*headMessage*/ undefined, intersectionState)) { + return result; + } + // slower, fuller, this-instantiated check (necessary when comparing raw `this` types from base classes), see `subclassWithPolymorphicThisIsAssignable.ts` test for example + else if (result = isRelatedTo(getTypeWithThisArgument(constraint, source), target, RecursionFlags.Source, reportErrors && constraint !== unknownType && !(targetFlags & sourceFlags & TypeFlags.TypeParameter), /*headMessage*/ undefined, intersectionState)) { + return result; + } + if (isMappedTypeGenericIndexedAccess(source)) { + // For an indexed access type { [P in K]: E}[X], above we have already explored an instantiation of E with X + // substituted for P. We also want to explore type { [P in K]: E }[C], where C is the constraint of X. + const indexConstraint = getConstraintOfType((source as IndexedAccessType).indexType); + if (indexConstraint) { + if (result = isRelatedTo(getIndexedAccessType((source as IndexedAccessType).objectType, indexConstraint), target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + } + } + } + else if (sourceFlags & TypeFlags.Index) { + const isDeferredMappedIndex = shouldDeferIndexType((source as IndexType).type, (source as IndexType).indexFlags) && getObjectFlags((source as IndexType).type) & ObjectFlags.Mapped; + if (result = isRelatedTo(stringNumberSymbolType, target, RecursionFlags.Source, reportErrors && !isDeferredMappedIndex)) { + return result; + } + if (isDeferredMappedIndex) { + const mappedType = (source as IndexType).type as MappedType; + const nameType = getNameTypeFromMappedType(mappedType); + // Unlike on the target side, on the source side we do *not* include the generic part of the `nameType`, since that comes from a + // (potentially anonymous) mapped type local type parameter, so that'd never assign outside the mapped type body, but we still want to + // allow assignments of index types of identical (or similar enough) mapped types. + // eg, `keyof {[X in keyof A]: Obj[X]}` should be assignable to `keyof {[Y in keyof A]: Tup[Y]}` because both map over the same set of keys (`keyof A`). + // Without this source-side breakdown, a `keyof {[X in keyof A]: Obj[X]}` style type won't be assignable to anything except itself, which is much too strict. + const sourceMappedKeys = nameType && isMappedTypeWithKeyofConstraintDeclaration(mappedType) ? getApparentMappedTypeKeys(nameType, mappedType) : (nameType || getConstraintTypeFromMappedType(mappedType)); + if (result = isRelatedTo(sourceMappedKeys, target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + } + else if (sourceFlags & TypeFlags.TemplateLiteral && !(targetFlags & TypeFlags.Object)) { + if (!(targetFlags & TypeFlags.TemplateLiteral)) { + const constraint = getBaseConstraintOfType(source); + if (constraint && constraint !== source && (result = isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors))) { + return result; + } + } + } + else if (sourceFlags & TypeFlags.StringMapping) { + if (targetFlags & TypeFlags.StringMapping) { + if ((source as StringMappingType).symbol !== (target as StringMappingType).symbol) { + return Ternary.False; + } + if (result = isRelatedTo((source as StringMappingType).type, (target as StringMappingType).type, RecursionFlags.Both, reportErrors)) { + return result; + } + } + else { + const constraint = getBaseConstraintOfType(source); + if (constraint && (result = isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors))) { + return result; + } + } + } + else if (sourceFlags & TypeFlags.Conditional) { + // If we reach 10 levels of nesting for the same conditional type, assume it is an infinitely expanding recursive + // conditional type and bail out with a Ternary.Maybe result. + if (isDeeplyNestedType(source, sourceStack, sourceDepth, 10)) { + return Ternary.Maybe; + } + if (targetFlags & TypeFlags.Conditional) { + // Two conditional types 'T1 extends U1 ? X1 : Y1' and 'T2 extends U2 ? X2 : Y2' are related if + // one of T1 and T2 is related to the other, U1 and U2 are identical types, X1 is related to X2, + // and Y1 is related to Y2. + const sourceParams = (source as ConditionalType).root.inferTypeParameters; + let sourceExtends = (source as ConditionalType).extendsType; + let mapper: TypeMapper | undefined; + if (sourceParams) { + // If the source has infer type parameters, we instantiate them in the context of the target + const ctx = createInferenceContext(sourceParams, /*signature*/ undefined, InferenceFlags.None, isRelatedToWorker); + inferTypes(ctx.inferences, (target as ConditionalType).extendsType, sourceExtends, InferencePriority.NoConstraints | InferencePriority.AlwaysStrict); + sourceExtends = instantiateType(sourceExtends, ctx.mapper); + mapper = ctx.mapper; + } + if ( + isTypeIdenticalTo(sourceExtends, (target as ConditionalType).extendsType) && + (isRelatedTo((source as ConditionalType).checkType, (target as ConditionalType).checkType, RecursionFlags.Both) || isRelatedTo((target as ConditionalType).checkType, (source as ConditionalType).checkType, RecursionFlags.Both)) + ) { + if (result = isRelatedTo(instantiateType(getTrueTypeFromConditionalType(source as ConditionalType), mapper), getTrueTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, reportErrors)) { + result &= isRelatedTo(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target as ConditionalType), RecursionFlags.Both, reportErrors); + } + if (result) { + return result; + } + } + } + // conditionals can be related to one another via normal constraint, as, eg, `A extends B ? O : never` should be assignable to `O` + // when `O` is a conditional (`never` is trivially assignable to `O`, as is `O`!). + const defaultConstraint = getDefaultConstraintOfConditionalType(source as ConditionalType); + if (defaultConstraint) { + if (result = isRelatedTo(defaultConstraint, target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + // conditionals aren't related to one another via distributive constraint as it is much too inaccurate and allows way + // more assignments than are desirable (since it maps the source check type to its constraint, it loses information). + const distributiveConstraint = !(targetFlags & TypeFlags.Conditional) && hasNonCircularBaseConstraint(source) ? getConstraintOfDistributiveConditionalType(source as ConditionalType) : undefined; + if (distributiveConstraint) { + resetErrorInfo(saveErrorInfo); + if (result = isRelatedTo(distributiveConstraint, target, RecursionFlags.Source, reportErrors)) { + return result; + } + } + } + else { + // An empty object type is related to any mapped type that includes a '?' modifier. + if (relation !== subtypeRelation && relation !== strictSubtypeRelation && isPartialMappedType(target) && isEmptyObjectType(source)) { + return Ternary.True; + } + if (isGenericMappedType(target)) { + if (isGenericMappedType(source)) { + if (result = mappedTypeRelatedTo(source, target, reportErrors)) { + return result; + } + } + return Ternary.False; + } + const sourceIsPrimitive = !!(sourceFlags & TypeFlags.Primitive); + if (relation !== identityRelation) { + source = getApparentType(source); + sourceFlags = source.flags; + } + else if (isGenericMappedType(source)) { + return Ternary.False; + } + if ( + getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && (source as TypeReference).target === (target as TypeReference).target && + !isTupleType(source) && !(isMarkerType(source) || isMarkerType(target)) + ) { + // When strictNullChecks is disabled, the element type of the empty array literal is undefinedWideningType, + // and an empty array literal wouldn't be assignable to a `never[]` without this check. + if (isEmptyArrayLiteralType(source)) { + return Ternary.True; + } + // We have type references to the same generic type, and the type references are not marker + // type references (which are intended by be compared structurally). Obtain the variance + // information for the type parameters and relate the type arguments accordingly. + const variances = getVariances((source as TypeReference).target); + // We return Ternary.Maybe for a recursive invocation of getVariances (signalled by emptyArray). This + // effectively means we measure variance only from type parameter occurrences that aren't nested in + // recursive instantiations of the generic type. + if (variances === emptyArray) { + return Ternary.Unknown; + } + const varianceResult = relateVariances(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), variances, intersectionState); + if (varianceResult !== undefined) { + return varianceResult; + } + } + else if (isReadonlyArrayType(target) ? everyType(source, isArrayOrTupleType) : isArrayType(target) && everyType(source, t => isTupleType(t) && !t.target.readonly)) { + if (relation !== identityRelation) { + return isRelatedTo(getIndexTypeOfType(source, numberType) || anyType, getIndexTypeOfType(target, numberType) || anyType, RecursionFlags.Both, reportErrors); + } + else { + // By flags alone, we know that the `target` is a readonly array while the source is a normal array or tuple + // or `target` is an array and source is a tuple - in both cases the types cannot be identical, by construction + return Ternary.False; + } + } + else if (isGenericTupleType(source) && isTupleType(target) && !isGenericTupleType(target)) { + const constraint = getBaseConstraintOrType(source); + if (constraint !== source) { + return isRelatedTo(constraint, target, RecursionFlags.Source, reportErrors); + } + } + // A fresh empty object type is never a subtype of a non-empty object type. This ensures fresh({}) <: { [x: string]: xxx } + // but not vice-versa. Without this rule, those types would be mutual subtypes. + else if ((relation === subtypeRelation || relation === strictSubtypeRelation) && isEmptyObjectType(target) && getObjectFlags(target) & ObjectFlags.FreshLiteral && !isEmptyObjectType(source)) { + return Ternary.False; + } + // Even if relationship doesn't hold for unions, intersections, or generic type references, + // it may hold in a structural comparison. + // In a check of the form X = A & B, we will have previously checked if A relates to X or B relates + // to X. Failing both of those we want to check if the aggregation of A and B's members structurally + // relates to X. Thus, we include intersection types on the source side here. + if (sourceFlags & (TypeFlags.Object | TypeFlags.Intersection) && targetFlags & TypeFlags.Object) { + // Report structural errors only if we haven't reported any errors yet + const reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo.errorInfo && !sourceIsPrimitive; + result = propertiesRelatedTo(source, target, reportStructuralErrors, /*excludedProperties*/ undefined, /*optionalsOnly*/ false, intersectionState); + if (result) { + result &= signaturesRelatedTo(source, target, SignatureKind.Call, reportStructuralErrors, intersectionState); + if (result) { + result &= signaturesRelatedTo(source, target, SignatureKind.Construct, reportStructuralErrors, intersectionState); + if (result) { + result &= indexSignaturesRelatedTo(source, target, sourceIsPrimitive, reportStructuralErrors, intersectionState); + } + } + } + if (varianceCheckFailed && result) { + errorInfo = originalErrorInfo || errorInfo || saveErrorInfo.errorInfo; // Use variance error (there is no structural one) and return false + } + else if (result) { + return result; + } + } + // If S is an object type and T is a discriminated union, S may be related to T if + // there exists a constituent of T for every combination of the discriminants of S + // with respect to T. We do not report errors here, as we will use the existing + // error result from checking each constituent of the union. + if (sourceFlags & (TypeFlags.Object | TypeFlags.Intersection) && targetFlags & TypeFlags.Union) { + const objectOnlyTarget = extractTypesOfKind(target, TypeFlags.Object | TypeFlags.Intersection | TypeFlags.Substitution); + if (objectOnlyTarget.flags & TypeFlags.Union) { + const result = typeRelatedToDiscriminatedType(source, objectOnlyTarget as UnionType); + if (result) { + return result; + } + } + } + } + return Ternary.False; + + function countMessageChainBreadth(info: DiagnosticMessageChain[] | undefined): number { + if (!info) return 0; + return reduceLeft(info, (value, chain) => value + 1 + countMessageChainBreadth(chain.next), 0); + } + + function relateVariances(sourceTypeArguments: readonly Type[] | undefined, targetTypeArguments: readonly Type[] | undefined, variances: VarianceFlags[], intersectionState: IntersectionState) { + if (result = typeArgumentsRelatedTo(sourceTypeArguments, targetTypeArguments, variances, reportErrors, intersectionState)) { + return result; + } + if (some(variances, v => !!(v & VarianceFlags.AllowsStructuralFallback))) { + // If some type parameter was `Unmeasurable` or `Unreliable`, and we couldn't pass by assuming it was identical, then we + // have to allow a structural fallback check + // We elide the variance-based error elaborations, since those might not be too helpful, since we'll potentially + // be assuming identity of the type parameter. + originalErrorInfo = undefined; + resetErrorInfo(saveErrorInfo); + return undefined; + } + const allowStructuralFallback = targetTypeArguments && hasCovariantVoidArgument(targetTypeArguments, variances); + varianceCheckFailed = !allowStructuralFallback; + // The type arguments did not relate appropriately, but it may be because we have no variance + // information (in which case typeArgumentsRelatedTo defaulted to covariance for all type + // arguments). It might also be the case that the target type has a 'void' type argument for + // a covariant type parameter that is only used in return positions within the generic type + // (in which case any type argument is permitted on the source side). In those cases we proceed + // with a structural comparison. Otherwise, we know for certain the instantiations aren't + // related and we can return here. + if (variances !== emptyArray && !allowStructuralFallback) { + // In some cases generic types that are covariant in regular type checking mode become + // invariant in --strictFunctionTypes mode because one or more type parameters are used in + // both co- and contravariant positions. In order to make it easier to diagnose *why* such + // types are invariant, if any of the type parameters are invariant we reset the reported + // errors and instead force a structural comparison (which will include elaborations that + // reveal the reason). + // We can switch on `reportErrors` here, since varianceCheckFailed guarantees we return `False`, + // we can return `False` early here to skip calculating the structural error message we don't need. + if (varianceCheckFailed && !(reportErrors && some(variances, v => (v & VarianceFlags.VarianceMask) === VarianceFlags.Invariant))) { + return Ternary.False; + } + // We remember the original error information so we can restore it in case the structural + // comparison unexpectedly succeeds. This can happen when the structural comparison result + // is a Ternary.Maybe for example caused by the recursion depth limiter. + originalErrorInfo = errorInfo; + resetErrorInfo(saveErrorInfo); + } + } + } + + // A type [P in S]: X is related to a type [Q in T]: Y if T is related to S and X' is + // related to Y, where X' is an instantiation of X in which P is replaced with Q. Notice + // that S and T are contra-variant whereas X and Y are co-variant. + function mappedTypeRelatedTo(source: MappedType, target: MappedType, reportErrors: boolean): Ternary { + const modifiersRelated = relation === comparableRelation || (relation === identityRelation ? getMappedTypeModifiers(source) === getMappedTypeModifiers(target) : + getCombinedMappedTypeOptionality(source) <= getCombinedMappedTypeOptionality(target)); + if (modifiersRelated) { + let result: Ternary; + const targetConstraint = getConstraintTypeFromMappedType(target); + const sourceConstraint = instantiateType(getConstraintTypeFromMappedType(source), getCombinedMappedTypeOptionality(source) < 0 ? reportUnmeasurableMapper : reportUnreliableMapper); + if (result = isRelatedTo(targetConstraint, sourceConstraint, RecursionFlags.Both, reportErrors)) { + const mapper = createTypeMapper([getTypeParameterFromMappedType(source)], [getTypeParameterFromMappedType(target)]); + if (instantiateType(getNameTypeFromMappedType(source), mapper) === instantiateType(getNameTypeFromMappedType(target), mapper)) { + return result & isRelatedTo(instantiateType(getTemplateTypeFromMappedType(source), mapper), getTemplateTypeFromMappedType(target), RecursionFlags.Both, reportErrors); + } + } + } + return Ternary.False; + } + + function typeRelatedToDiscriminatedType(source: Type, target: UnionType) { + // 1. Generate the combinations of discriminant properties & types 'source' can satisfy. + // a. If the number of combinations is above a set limit, the comparison is too complex. + // 2. Filter 'target' to the subset of types whose discriminants exist in the matrix. + // a. If 'target' does not satisfy all discriminants in the matrix, 'source' is not related. + // 3. For each type in the filtered 'target', determine if all non-discriminant properties of + // 'target' are related to a property in 'source'. + // + // NOTE: See ~/tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithDiscriminatedUnion.ts + // for examples. + + const sourceProperties = getPropertiesOfType(source); + const sourcePropertiesFiltered = findDiscriminantProperties(sourceProperties, target); + if (!sourcePropertiesFiltered) return Ternary.False; + + // Though we could compute the number of combinations as we generate + // the matrix, this would incur additional memory overhead due to + // array allocations. To reduce this overhead, we first compute + // the number of combinations to ensure we will not surpass our + // fixed limit before incurring the cost of any allocations: + let numCombinations = 1; + for (const sourceProperty of sourcePropertiesFiltered) { + numCombinations *= countTypes(getNonMissingTypeOfSymbol(sourceProperty)); + if (numCombinations > 25) { + // We've reached the complexity limit. + tracing?.instant(tracing.Phase.CheckTypes, "typeRelatedToDiscriminatedType_DepthLimit", { sourceId: source.id, targetId: target.id, numCombinations }); + return Ternary.False; + } + } + + // Compute the set of types for each discriminant property. + const sourceDiscriminantTypes: Type[][] = new Array(sourcePropertiesFiltered.length); + const excludedProperties = new Set<__String>(); + for (let i = 0; i < sourcePropertiesFiltered.length; i++) { + const sourceProperty = sourcePropertiesFiltered[i]; + const sourcePropertyType = getNonMissingTypeOfSymbol(sourceProperty); + sourceDiscriminantTypes[i] = sourcePropertyType.flags & TypeFlags.Union + ? (sourcePropertyType as UnionType).types + : [sourcePropertyType]; + excludedProperties.add(sourceProperty.escapedName); + } + + // Match each combination of the cartesian product of discriminant properties to one or more + // constituents of 'target'. If any combination does not have a match then 'source' is not relatable. + const discriminantCombinations = cartesianProduct(sourceDiscriminantTypes); + const matchingTypes: Type[] = []; + for (const combination of discriminantCombinations) { + let hasMatch = false; + outer: + for (const type of target.types) { + for (let i = 0; i < sourcePropertiesFiltered.length; i++) { + const sourceProperty = sourcePropertiesFiltered[i]; + const targetProperty = getPropertyOfType(type, sourceProperty.escapedName); + if (!targetProperty) continue outer; + if (sourceProperty === targetProperty) continue; + // We compare the source property to the target in the context of a single discriminant type. + const related = propertyRelatedTo(source, target, sourceProperty, targetProperty, _ => combination[i], /*reportErrors*/ false, IntersectionState.None, /*skipOptional*/ strictNullChecks || relation === comparableRelation); + // If the target property could not be found, or if the properties were not related, + // then this constituent is not a match. + if (!related) { + continue outer; + } + } + pushIfUnique(matchingTypes, type, equateValues); + hasMatch = true; + } + if (!hasMatch) { + // We failed to match any type for this combination. + return Ternary.False; + } + } + + // Compare the remaining non-discriminant properties of each match. + let result = Ternary.True; + for (const type of matchingTypes) { + result &= propertiesRelatedTo(source, type, /*reportErrors*/ false, excludedProperties, /*optionalsOnly*/ false, IntersectionState.None); + if (result) { + result &= signaturesRelatedTo(source, type, SignatureKind.Call, /*reportErrors*/ false, IntersectionState.None); + if (result) { + result &= signaturesRelatedTo(source, type, SignatureKind.Construct, /*reportErrors*/ false, IntersectionState.None); + if (result && !(isTupleType(source) && isTupleType(type))) { + // Comparing numeric index types when both `source` and `type` are tuples is unnecessary as the + // element types should be sufficiently covered by `propertiesRelatedTo`. It also causes problems + // with index type assignability as the types for the excluded discriminants are still included + // in the index type. + result &= indexSignaturesRelatedTo(source, type, /*sourceIsPrimitive*/ false, /*reportErrors*/ false, IntersectionState.None); + } + } + } + if (!result) { + return result; + } + } + return result; + } + + function excludeProperties(properties: Symbol[], excludedProperties: Set<__String> | undefined) { + if (!excludedProperties || properties.length === 0) return properties; + let result: Symbol[] | undefined; + for (let i = 0; i < properties.length; i++) { + if (!excludedProperties.has(properties[i].escapedName)) { + if (result) { + result.push(properties[i]); + } + } + else if (!result) { + result = properties.slice(0, i); + } + } + return result || properties; + } + + function isPropertySymbolTypeRelated(sourceProp: Symbol, targetProp: Symbol, getTypeOfSourceProperty: (sym: Symbol) => Type, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const targetIsOptional = strictNullChecks && !!(getCheckFlags(targetProp) & CheckFlags.Partial); + const effectiveTarget = addOptionality(getNonMissingTypeOfSymbol(targetProp), /*isProperty*/ false, targetIsOptional); + const effectiveSource = getTypeOfSourceProperty(sourceProp); + return isRelatedTo(effectiveSource, effectiveTarget, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + + function propertyRelatedTo(source: Type, target: Type, sourceProp: Symbol, targetProp: Symbol, getTypeOfSourceProperty: (sym: Symbol) => Type, reportErrors: boolean, intersectionState: IntersectionState, skipOptional: boolean): Ternary { + const sourcePropFlags = getDeclarationModifierFlagsFromSymbol(sourceProp); + const targetPropFlags = getDeclarationModifierFlagsFromSymbol(targetProp); + if (sourcePropFlags & ModifierFlags.Private || targetPropFlags & ModifierFlags.Private) { + if (sourceProp.valueDeclaration !== targetProp.valueDeclaration) { + if (reportErrors) { + if (sourcePropFlags & ModifierFlags.Private && targetPropFlags & ModifierFlags.Private) { + reportError(Diagnostics.Types_have_separate_declarations_of_a_private_property_0, symbolToString(targetProp)); + } + else { + reportError(Diagnostics.Property_0_is_private_in_type_1_but_not_in_type_2, symbolToString(targetProp), typeToString(sourcePropFlags & ModifierFlags.Private ? source : target), typeToString(sourcePropFlags & ModifierFlags.Private ? target : source)); + } + } + return Ternary.False; + } + } + else if (targetPropFlags & ModifierFlags.Protected) { + if (!isValidOverrideOf(sourceProp, targetProp)) { + if (reportErrors) { + reportError(Diagnostics.Property_0_is_protected_but_type_1_is_not_a_class_derived_from_2, symbolToString(targetProp), typeToString(getDeclaringClass(sourceProp) || source), typeToString(getDeclaringClass(targetProp) || target)); + } + return Ternary.False; + } + } + else if (sourcePropFlags & ModifierFlags.Protected) { + if (reportErrors) { + reportError(Diagnostics.Property_0_is_protected_in_type_1_but_public_in_type_2, symbolToString(targetProp), typeToString(source), typeToString(target)); + } + return Ternary.False; + } + + // Ensure {readonly a: whatever} is not a subtype of {a: whatever}, + // while {a: whatever} is a subtype of {readonly a: whatever}. + // This ensures the subtype relationship is ordered, and preventing declaration order + // from deciding which type "wins" in union subtype reduction. + // They're still assignable to one another, since `readonly` doesn't affect assignability. + // This is only applied during the strictSubtypeRelation -- currently used in subtype reduction + if ( + relation === strictSubtypeRelation && + isReadonlySymbol(sourceProp) && !isReadonlySymbol(targetProp) + ) { + return Ternary.False; + } + // If the target comes from a partial union prop, allow `undefined` in the target type + const related = isPropertySymbolTypeRelated(sourceProp, targetProp, getTypeOfSourceProperty, reportErrors, intersectionState); + if (!related) { + if (reportErrors) { + reportIncompatibleError(Diagnostics.Types_of_property_0_are_incompatible, symbolToString(targetProp)); + } + return Ternary.False; + } + // When checking for comparability, be more lenient with optional properties. + if (!skipOptional && sourceProp.flags & SymbolFlags.Optional && targetProp.flags & SymbolFlags.ClassMember && !(targetProp.flags & SymbolFlags.Optional)) { + // TypeScript 1.0 spec (April 2014): 3.8.3 + // S is a subtype of a type T, and T is a supertype of S if ... + // S' and T are object types and, for each member M in T.. + // M is a property and S' contains a property N where + // if M is a required property, N is also a required property + // (M - property in T) + // (N - property in S) + if (reportErrors) { + reportError(Diagnostics.Property_0_is_optional_in_type_1_but_required_in_type_2, symbolToString(targetProp), typeToString(source), typeToString(target)); + } + return Ternary.False; + } + return related; + } + + function reportUnmatchedProperty(source: Type, target: Type, unmatchedProperty: Symbol, requireOptionalProperties: boolean) { + let shouldSkipElaboration = false; + // give specific error in case where private names have the same description + if ( + unmatchedProperty.valueDeclaration + && isNamedDeclaration(unmatchedProperty.valueDeclaration) + && isPrivateIdentifier(unmatchedProperty.valueDeclaration.name) + && source.symbol + && source.symbol.flags & SymbolFlags.Class + ) { + const privateIdentifierDescription = unmatchedProperty.valueDeclaration.name.escapedText; + const symbolTableKey = getSymbolNameForPrivateIdentifier(source.symbol, privateIdentifierDescription); + if (symbolTableKey && getPropertyOfType(source, symbolTableKey)) { + const sourceName = factory.getDeclarationName(source.symbol.valueDeclaration); + const targetName = factory.getDeclarationName(target.symbol.valueDeclaration); + reportError( + Diagnostics.Property_0_in_type_1_refers_to_a_different_member_that_cannot_be_accessed_from_within_type_2, + diagnosticName(privateIdentifierDescription), + diagnosticName(sourceName.escapedText === "" ? anon : sourceName), + diagnosticName(targetName.escapedText === "" ? anon : targetName), + ); + return; + } + } + const props = arrayFrom(getUnmatchedProperties(source, target, requireOptionalProperties, /*matchDiscriminantProperties*/ false)); + if ( + !headMessage || (headMessage.code !== Diagnostics.Class_0_incorrectly_implements_interface_1.code && + headMessage.code !== Diagnostics.Class_0_incorrectly_implements_class_1_Did_you_mean_to_extend_1_and_inherit_its_members_as_a_subclass.code) + ) { + shouldSkipElaboration = true; // Retain top-level error for interface implementing issues, otherwise omit it + } + if (props.length === 1) { + const propName = symbolToString(unmatchedProperty, /*enclosingDeclaration*/ undefined, SymbolFlags.None, SymbolFormatFlags.AllowAnyNodeKind | SymbolFormatFlags.WriteComputedProps); + reportError(Diagnostics.Property_0_is_missing_in_type_1_but_required_in_type_2, propName, ...getTypeNamesForErrorDisplay(source, target)); + if (length(unmatchedProperty.declarations)) { + associateRelatedInfo(createDiagnosticForNode(unmatchedProperty.declarations![0], Diagnostics._0_is_declared_here, propName)); + } + if (shouldSkipElaboration && errorInfo) { + overrideNextErrorInfo++; + } + } + else if (tryElaborateArrayLikeErrors(source, target, /*reportErrors*/ false)) { + if (props.length > 5) { // arbitrary cutoff for too-long list form + reportError(Diagnostics.Type_0_is_missing_the_following_properties_from_type_1_Colon_2_and_3_more, typeToString(source), typeToString(target), map(props.slice(0, 4), p => symbolToString(p)).join(", "), props.length - 4); + } + else { + reportError(Diagnostics.Type_0_is_missing_the_following_properties_from_type_1_Colon_2, typeToString(source), typeToString(target), map(props, p => symbolToString(p)).join(", ")); + } + if (shouldSkipElaboration && errorInfo) { + overrideNextErrorInfo++; + } + } + // No array like or unmatched property error - just issue top level error (errorInfo = undefined) + } + + function propertiesRelatedTo(source: Type, target: Type, reportErrors: boolean, excludedProperties: Set<__String> | undefined, optionalsOnly: boolean, intersectionState: IntersectionState): Ternary { + if (relation === identityRelation) { + return propertiesIdenticalTo(source, target, excludedProperties); + } + let result = Ternary.True; + if (isTupleType(target)) { + if (isArrayOrTupleType(source)) { + if (!target.target.readonly && (isReadonlyArrayType(source) || isTupleType(source) && source.target.readonly)) { + return Ternary.False; + } + const sourceArity = getTypeReferenceArity(source); + const targetArity = getTypeReferenceArity(target); + const sourceRestFlag = isTupleType(source) ? source.target.combinedFlags & ElementFlags.Rest : ElementFlags.Rest; + const targetHasRestElement = !!(target.target.combinedFlags & ElementFlags.Variable); + const sourceMinLength = isTupleType(source) ? source.target.minLength : 0; + const targetMinLength = target.target.minLength; + if (!sourceRestFlag && sourceArity < targetMinLength) { + if (reportErrors) { + reportError(Diagnostics.Source_has_0_element_s_but_target_requires_1, sourceArity, targetMinLength); + } + return Ternary.False; + } + if (!targetHasRestElement && targetArity < sourceMinLength) { + if (reportErrors) { + reportError(Diagnostics.Source_has_0_element_s_but_target_allows_only_1, sourceMinLength, targetArity); + } + return Ternary.False; + } + if (!targetHasRestElement && (sourceRestFlag || targetArity < sourceArity)) { + if (reportErrors) { + if (sourceMinLength < targetMinLength) { + reportError(Diagnostics.Target_requires_0_element_s_but_source_may_have_fewer, targetMinLength); + } + else { + reportError(Diagnostics.Target_allows_only_0_element_s_but_source_may_have_more, targetArity); + } + } + return Ternary.False; + } + const sourceTypeArguments = getTypeArguments(source); + const targetTypeArguments = getTypeArguments(target); + const targetStartCount = getStartElementCount(target.target, ElementFlags.NonRest); + const targetEndCount = getEndElementCount(target.target, ElementFlags.NonRest); + let canExcludeDiscriminants = !!excludedProperties; + for (let sourcePosition = 0; sourcePosition < sourceArity; sourcePosition++) { + const sourceFlags = isTupleType(source) ? source.target.elementFlags[sourcePosition] : ElementFlags.Rest; + const sourcePositionFromEnd = sourceArity - 1 - sourcePosition; + + const targetPosition = targetHasRestElement && sourcePosition >= targetStartCount + ? targetArity - 1 - Math.min(sourcePositionFromEnd, targetEndCount) + : sourcePosition; + + const targetFlags = target.target.elementFlags[targetPosition]; + + if (targetFlags & ElementFlags.Variadic && !(sourceFlags & ElementFlags.Variadic)) { + if (reportErrors) { + reportError(Diagnostics.Source_provides_no_match_for_variadic_element_at_position_0_in_target, targetPosition); + } + return Ternary.False; + } + if (sourceFlags & ElementFlags.Variadic && !(targetFlags & ElementFlags.Variable)) { + if (reportErrors) { + reportError(Diagnostics.Variadic_element_at_position_0_in_source_does_not_match_element_at_position_1_in_target, sourcePosition, targetPosition); + } + return Ternary.False; + } + if (targetFlags & ElementFlags.Required && !(sourceFlags & ElementFlags.Required)) { + if (reportErrors) { + reportError(Diagnostics.Source_provides_no_match_for_required_element_at_position_0_in_target, targetPosition); + } + return Ternary.False; + } + // We can only exclude discriminant properties if we have not yet encountered a variable-length element. + if (canExcludeDiscriminants) { + if (sourceFlags & ElementFlags.Variable || targetFlags & ElementFlags.Variable) { + canExcludeDiscriminants = false; + } + if (canExcludeDiscriminants && excludedProperties?.has(("" + sourcePosition) as __String)) { + continue; + } + } + + const sourceType = removeMissingType(sourceTypeArguments[sourcePosition], !!(sourceFlags & targetFlags & ElementFlags.Optional)); + const targetType = targetTypeArguments[targetPosition]; + + const targetCheckType = sourceFlags & ElementFlags.Variadic && targetFlags & ElementFlags.Rest ? createArrayType(targetType) : + removeMissingType(targetType, !!(targetFlags & ElementFlags.Optional)); + const related = isRelatedTo(sourceType, targetCheckType, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + if (reportErrors && (targetArity > 1 || sourceArity > 1)) { + if (targetHasRestElement && sourcePosition >= targetStartCount && sourcePositionFromEnd >= targetEndCount && targetStartCount !== sourceArity - targetEndCount - 1) { + reportIncompatibleError(Diagnostics.Type_at_positions_0_through_1_in_source_is_not_compatible_with_type_at_position_2_in_target, targetStartCount, sourceArity - targetEndCount - 1, targetPosition); + } + else { + reportIncompatibleError(Diagnostics.Type_at_position_0_in_source_is_not_compatible_with_type_at_position_1_in_target, sourcePosition, targetPosition); + } + } + return Ternary.False; + } + result &= related; + } + return result; + } + if (target.target.combinedFlags & ElementFlags.Variable) { + return Ternary.False; + } + } + const requireOptionalProperties = (relation === subtypeRelation || relation === strictSubtypeRelation) && !isObjectLiteralType(source) && !isEmptyArrayLiteralType(source) && !isTupleType(source); + const unmatchedProperty = getUnmatchedProperty(source, target, requireOptionalProperties, /*matchDiscriminantProperties*/ false); + if (unmatchedProperty) { + if (reportErrors && shouldReportUnmatchedPropertyError(source, target)) { + reportUnmatchedProperty(source, target, unmatchedProperty, requireOptionalProperties); + } + return Ternary.False; + } + if (isObjectLiteralType(target)) { + for (const sourceProp of excludeProperties(getPropertiesOfType(source), excludedProperties)) { + if (!getPropertyOfObjectType(target, sourceProp.escapedName)) { + const sourceType = getTypeOfSymbol(sourceProp); + if (!(sourceType.flags & TypeFlags.Undefined)) { + if (reportErrors) { + reportError(Diagnostics.Property_0_does_not_exist_on_type_1, symbolToString(sourceProp), typeToString(target)); + } + return Ternary.False; + } + } + } + } + // We only call this for union target types when we're attempting to do excess property checking - in those cases, we want to get _all possible props_ + // from the target union, across all members + const properties = getPropertiesOfType(target); + const numericNamesOnly = isTupleType(source) && isTupleType(target); + for (const targetProp of excludeProperties(properties, excludedProperties)) { + const name = targetProp.escapedName; + if (!(targetProp.flags & SymbolFlags.Prototype) && (!numericNamesOnly || isNumericLiteralName(name) || name === "length") && (!optionalsOnly || targetProp.flags & SymbolFlags.Optional)) { + const sourceProp = getPropertyOfType(source, name); + if (sourceProp && sourceProp !== targetProp) { + const related = propertyRelatedTo(source, target, sourceProp, targetProp, getNonMissingTypeOfSymbol, reportErrors, intersectionState, relation === comparableRelation); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + } + return result; + } + + function propertiesIdenticalTo(source: Type, target: Type, excludedProperties: Set<__String> | undefined): Ternary { + if (!(source.flags & TypeFlags.Object && target.flags & TypeFlags.Object)) { + return Ternary.False; + } + const sourceProperties = excludeProperties(getPropertiesOfObjectType(source), excludedProperties); + const targetProperties = excludeProperties(getPropertiesOfObjectType(target), excludedProperties); + if (sourceProperties.length !== targetProperties.length) { + return Ternary.False; + } + let result = Ternary.True; + for (const sourceProp of sourceProperties) { + const targetProp = getPropertyOfObjectType(target, sourceProp.escapedName); + if (!targetProp) { + return Ternary.False; + } + const related = compareProperties(sourceProp, targetProp, isRelatedTo); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function signaturesRelatedTo(source: Type, target: Type, kind: SignatureKind, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + if (relation === identityRelation) { + return signaturesIdenticalTo(source, target, kind); + } + if (target === anyFunctionType || source === anyFunctionType) { + return Ternary.True; + } + + const sourceIsJSConstructor = source.symbol && isJSConstructor(source.symbol.valueDeclaration); + const targetIsJSConstructor = target.symbol && isJSConstructor(target.symbol.valueDeclaration); + + const sourceSignatures = getSignaturesOfType( + source, + (sourceIsJSConstructor && kind === SignatureKind.Construct) ? + SignatureKind.Call : kind, + ); + const targetSignatures = getSignaturesOfType( + target, + (targetIsJSConstructor && kind === SignatureKind.Construct) ? + SignatureKind.Call : kind, + ); + + if (kind === SignatureKind.Construct && sourceSignatures.length && targetSignatures.length) { + const sourceIsAbstract = !!(sourceSignatures[0].flags & SignatureFlags.Abstract); + const targetIsAbstract = !!(targetSignatures[0].flags & SignatureFlags.Abstract); + if (sourceIsAbstract && !targetIsAbstract) { + // An abstract constructor type is not assignable to a non-abstract constructor type + // as it would otherwise be possible to new an abstract class. Note that the assignability + // check we perform for an extends clause excludes construct signatures from the target, + // so this check never proceeds. + if (reportErrors) { + reportError(Diagnostics.Cannot_assign_an_abstract_constructor_type_to_a_non_abstract_constructor_type); + } + return Ternary.False; + } + if (!constructorVisibilitiesAreCompatible(sourceSignatures[0], targetSignatures[0], reportErrors)) { + return Ternary.False; + } + } + + let result = Ternary.True; + const incompatibleReporter = kind === SignatureKind.Construct ? reportIncompatibleConstructSignatureReturn : reportIncompatibleCallSignatureReturn; + const sourceObjectFlags = getObjectFlags(source); + const targetObjectFlags = getObjectFlags(target); + if ( + sourceObjectFlags & ObjectFlags.Instantiated && targetObjectFlags & ObjectFlags.Instantiated && source.symbol === target.symbol || + sourceObjectFlags & ObjectFlags.Reference && targetObjectFlags & ObjectFlags.Reference && (source as TypeReference).target === (target as TypeReference).target + ) { + // We have instantiations of the same anonymous type (which typically will be the type of a + // method). Simply do a pairwise comparison of the signatures in the two signature lists instead + // of the much more expensive N * M comparison matrix we explore below. We erase type parameters + // as they are known to always be the same. + Debug.assertEqual(sourceSignatures.length, targetSignatures.length); + for (let i = 0; i < targetSignatures.length; i++) { + const related = signatureRelatedTo(sourceSignatures[i], targetSignatures[i], /*erase*/ true, reportErrors, intersectionState, incompatibleReporter(sourceSignatures[i], targetSignatures[i])); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + else if (sourceSignatures.length === 1 && targetSignatures.length === 1) { + // For simple functions (functions with a single signature) we only erase type parameters for + // the comparable relation. Otherwise, if the source signature is generic, we instantiate it + // in the context of the target signature before checking the relationship. Ideally we'd do + // this regardless of the number of signatures, but the potential costs are prohibitive due + // to the quadratic nature of the logic below. + const eraseGenerics = relation === comparableRelation; + const sourceSignature = first(sourceSignatures); + const targetSignature = first(targetSignatures); + result = signatureRelatedTo(sourceSignature, targetSignature, eraseGenerics, reportErrors, intersectionState, incompatibleReporter(sourceSignature, targetSignature)); + if ( + !result && reportErrors && kind === SignatureKind.Construct && (sourceObjectFlags & targetObjectFlags) && + (targetSignature.declaration?.kind === SyntaxKind.Constructor || sourceSignature.declaration?.kind === SyntaxKind.Constructor) + ) { + const constructSignatureToString = (signature: Signature) => signatureToString(signature, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrowStyleSignature, kind); + reportError(Diagnostics.Type_0_is_not_assignable_to_type_1, constructSignatureToString(sourceSignature), constructSignatureToString(targetSignature)); + reportError(Diagnostics.Types_of_construct_signatures_are_incompatible); + return result; + } + } + else { + outer: + for (const t of targetSignatures) { + const saveErrorInfo = captureErrorCalculationState(); + // Only elaborate errors from the first failure + let shouldElaborateErrors = reportErrors; + for (const s of sourceSignatures) { + const related = signatureRelatedTo(s, t, /*erase*/ true, shouldElaborateErrors, intersectionState, incompatibleReporter(s, t)); + if (related) { + result &= related; + resetErrorInfo(saveErrorInfo); + continue outer; + } + shouldElaborateErrors = false; + } + if (shouldElaborateErrors) { + reportError(Diagnostics.Type_0_provides_no_match_for_the_signature_1, typeToString(source), signatureToString(t, /*enclosingDeclaration*/ undefined, /*flags*/ undefined, kind)); + } + return Ternary.False; + } + } + return result; + } + + function shouldReportUnmatchedPropertyError(source: Type, target: Type): boolean { + const typeCallSignatures = getSignaturesOfStructuredType(source, SignatureKind.Call); + const typeConstructSignatures = getSignaturesOfStructuredType(source, SignatureKind.Construct); + const typeProperties = getPropertiesOfObjectType(source); + if ((typeCallSignatures.length || typeConstructSignatures.length) && !typeProperties.length) { + if ( + (getSignaturesOfType(target, SignatureKind.Call).length && typeCallSignatures.length) || + (getSignaturesOfType(target, SignatureKind.Construct).length && typeConstructSignatures.length) + ) { + return true; // target has similar signature kinds to source, still focus on the unmatched property + } + return false; + } + return true; + } + + function reportIncompatibleCallSignatureReturn(siga: Signature, sigb: Signature) { + if (siga.parameters.length === 0 && sigb.parameters.length === 0) { + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target)); + } + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Call_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target)); + } + + function reportIncompatibleConstructSignatureReturn(siga: Signature, sigb: Signature) { + if (siga.parameters.length === 0 && sigb.parameters.length === 0) { + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signatures_with_no_arguments_have_incompatible_return_types_0_and_1, typeToString(source), typeToString(target)); + } + return (source: Type, target: Type) => reportIncompatibleError(Diagnostics.Construct_signature_return_types_0_and_1_are_incompatible, typeToString(source), typeToString(target)); + } + + /** + * See signatureAssignableTo, compareSignaturesIdentical + */ + function signatureRelatedTo(source: Signature, target: Signature, erase: boolean, reportErrors: boolean, intersectionState: IntersectionState, incompatibleReporter: (source: Type, target: Type) => void): Ternary { + const checkMode = relation === subtypeRelation ? SignatureCheckMode.StrictTopSignature : + relation === strictSubtypeRelation ? SignatureCheckMode.StrictTopSignature | SignatureCheckMode.StrictArity : + SignatureCheckMode.None; + return compareSignaturesRelated(erase ? getErasedSignature(source) : source, erase ? getErasedSignature(target) : target, checkMode, reportErrors, reportError, incompatibleReporter, isRelatedToWorker, reportUnreliableMapper); + function isRelatedToWorker(source: Type, target: Type, reportErrors?: boolean) { + return isRelatedTo(source, target, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + } + } + + function signaturesIdenticalTo(source: Type, target: Type, kind: SignatureKind): Ternary { + const sourceSignatures = getSignaturesOfType(source, kind); + const targetSignatures = getSignaturesOfType(target, kind); + if (sourceSignatures.length !== targetSignatures.length) { + return Ternary.False; + } + let result = Ternary.True; + for (let i = 0; i < sourceSignatures.length; i++) { + const related = compareSignaturesIdentical(sourceSignatures[i], targetSignatures[i], /*partialMatch*/ false, /*ignoreThisTypes*/ false, /*ignoreReturnTypes*/ false, isRelatedTo); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function membersRelatedToIndexInfo(source: Type, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + let result = Ternary.True; + const keyType = targetInfo.keyType; + const props = source.flags & TypeFlags.Intersection ? getPropertiesOfUnionOrIntersectionType(source as IntersectionType) : getPropertiesOfObjectType(source); + for (const prop of props) { + // Skip over ignored JSX and symbol-named members + if (isIgnoredJsxProperty(source, prop)) { + continue; + } + if (isApplicableIndexType(getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique), keyType)) { + const propType = getNonMissingTypeOfSymbol(prop); + const type = exactOptionalPropertyTypes || propType.flags & TypeFlags.Undefined || keyType === numberType || !(prop.flags & SymbolFlags.Optional) + ? propType + : getTypeWithFacts(propType, TypeFacts.NEUndefined); + const related = isRelatedTo(type, targetInfo.type, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related) { + if (reportErrors) { + reportError(Diagnostics.Property_0_is_incompatible_with_index_signature, symbolToString(prop)); + } + return Ternary.False; + } + result &= related; + } + } + for (const info of getIndexInfosOfType(source)) { + if (isApplicableIndexType(info.keyType, keyType)) { + const related = indexInfoRelatedTo(info, targetInfo, reportErrors, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + return result; + } + + function indexInfoRelatedTo(sourceInfo: IndexInfo, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState) { + const related = isRelatedTo(sourceInfo.type, targetInfo.type, RecursionFlags.Both, reportErrors, /*headMessage*/ undefined, intersectionState); + if (!related && reportErrors) { + if (sourceInfo.keyType === targetInfo.keyType) { + reportError(Diagnostics._0_index_signatures_are_incompatible, typeToString(sourceInfo.keyType)); + } + else { + reportError(Diagnostics._0_and_1_index_signatures_are_incompatible, typeToString(sourceInfo.keyType), typeToString(targetInfo.keyType)); + } + } + return related; + } + + function indexSignaturesRelatedTo(source: Type, target: Type, sourceIsPrimitive: boolean, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + if (relation === identityRelation) { + return indexSignaturesIdenticalTo(source, target); + } + const indexInfos = getIndexInfosOfType(target); + const targetHasStringIndex = some(indexInfos, info => info.keyType === stringType); + let result = Ternary.True; + for (const targetInfo of indexInfos) { + const related = relation !== strictSubtypeRelation && !sourceIsPrimitive && targetHasStringIndex && targetInfo.type.flags & TypeFlags.Any ? Ternary.True : + isGenericMappedType(source) && targetHasStringIndex ? isRelatedTo(getTemplateTypeFromMappedType(source), targetInfo.type, RecursionFlags.Both, reportErrors) : + typeRelatedToIndexInfo(source, targetInfo, reportErrors, intersectionState); + if (!related) { + return Ternary.False; + } + result &= related; + } + return result; + } + + function typeRelatedToIndexInfo(source: Type, targetInfo: IndexInfo, reportErrors: boolean, intersectionState: IntersectionState): Ternary { + const sourceInfo = getApplicableIndexInfo(source, targetInfo.keyType); + if (sourceInfo) { + return indexInfoRelatedTo(sourceInfo, targetInfo, reportErrors, intersectionState); + } + // Intersection constituents are never considered to have an inferred index signature. Also, in the strict subtype relation, + // only fresh object literals are considered to have inferred index signatures. This ensures { [x: string]: xxx } <: {} but + // not vice-versa. Without this rule, those types would be mutual strict subtypes. + if (!(intersectionState & IntersectionState.Source) && (relation !== strictSubtypeRelation || getObjectFlags(source) & ObjectFlags.FreshLiteral) && isObjectTypeWithInferableIndex(source)) { + return membersRelatedToIndexInfo(source, targetInfo, reportErrors, intersectionState); + } + if (reportErrors) { + reportError(Diagnostics.Index_signature_for_type_0_is_missing_in_type_1, typeToString(targetInfo.keyType), typeToString(source)); + } + return Ternary.False; + } + + function indexSignaturesIdenticalTo(source: Type, target: Type): Ternary { + const sourceInfos = getIndexInfosOfType(source); + const targetInfos = getIndexInfosOfType(target); + if (sourceInfos.length !== targetInfos.length) { + return Ternary.False; + } + for (const targetInfo of targetInfos) { + const sourceInfo = getIndexInfoOfType(source, targetInfo.keyType); + if (!(sourceInfo && isRelatedTo(sourceInfo.type, targetInfo.type, RecursionFlags.Both) && sourceInfo.isReadonly === targetInfo.isReadonly)) { + return Ternary.False; + } + } + return Ternary.True; + } + + function constructorVisibilitiesAreCompatible(sourceSignature: Signature, targetSignature: Signature, reportErrors: boolean) { + if (!sourceSignature.declaration || !targetSignature.declaration) { + return true; + } + + const sourceAccessibility = getSelectedEffectiveModifierFlags(sourceSignature.declaration, ModifierFlags.NonPublicAccessibilityModifier); + const targetAccessibility = getSelectedEffectiveModifierFlags(targetSignature.declaration, ModifierFlags.NonPublicAccessibilityModifier); + + // A public, protected and private signature is assignable to a private signature. + if (targetAccessibility === ModifierFlags.Private) { + return true; + } + + // A public and protected signature is assignable to a protected signature. + if (targetAccessibility === ModifierFlags.Protected && sourceAccessibility !== ModifierFlags.Private) { + return true; + } + + // Only a public signature is assignable to public signature. + if (targetAccessibility !== ModifierFlags.Protected && !sourceAccessibility) { + return true; + } + + if (reportErrors) { + reportError(Diagnostics.Cannot_assign_a_0_constructor_type_to_a_1_constructor_type, visibilityToString(sourceAccessibility), visibilityToString(targetAccessibility)); + } + + return false; + } + } + + function typeCouldHaveTopLevelSingletonTypes(type: Type): boolean { + // Okay, yes, 'boolean' is a union of 'true | false', but that's not useful + // in error reporting scenarios. If you need to use this function but that detail matters, + // feel free to add a flag. + if (type.flags & TypeFlags.Boolean) { + return false; + } + + if (type.flags & TypeFlags.UnionOrIntersection) { + return !!forEach((type as IntersectionType).types, typeCouldHaveTopLevelSingletonTypes); + } + + if (type.flags & TypeFlags.Instantiable) { + const constraint = getConstraintOfType(type); + if (constraint && constraint !== type) { + return typeCouldHaveTopLevelSingletonTypes(constraint); + } + } + + return isUnitType(type) || !!(type.flags & TypeFlags.TemplateLiteral) || !!(type.flags & TypeFlags.StringMapping); + } + + function getExactOptionalUnassignableProperties(source: Type, target: Type) { + if (isTupleType(source) && isTupleType(target)) return emptyArray; + return getPropertiesOfType(target) + .filter(targetProp => isExactOptionalPropertyMismatch(getTypeOfPropertyOfType(source, targetProp.escapedName), getTypeOfSymbol(targetProp))); + } + + function isExactOptionalPropertyMismatch(source: Type | undefined, target: Type | undefined) { + return !!source && !!target && maybeTypeOfKind(source, TypeFlags.Undefined) && !!containsMissingType(target); + } + + function getExactOptionalProperties(type: Type) { + return getPropertiesOfType(type).filter(targetProp => containsMissingType(getTypeOfSymbol(targetProp))); + } + + function getBestMatchingType(source: Type, target: UnionOrIntersectionType, isRelatedTo = compareTypesAssignable) { + return findMatchingDiscriminantType(source, target, isRelatedTo) || + findMatchingTypeReferenceOrTypeAliasReference(source, target) || + findBestTypeForObjectLiteral(source, target) || + findBestTypeForInvokable(source, target) || + findMostOverlappyType(source, target); + } + + function discriminateTypeByDiscriminableItems(target: UnionType, discriminators: (readonly [() => Type, __String])[], related: (source: Type, target: Type) => boolean | Ternary) { + const types = target.types; + const include: Ternary[] = types.map(t => t.flags & TypeFlags.Primitive ? Ternary.False : Ternary.True); + for (const [getDiscriminatingType, propertyName] of discriminators) { + // If the remaining target types include at least one with a matching discriminant, eliminate those that + // have non-matching discriminants. This ensures that we ignore erroneous discriminators and gradually + // refine the target set without eliminating every constituent (which would lead to `never`). + let matched = false; + for (let i = 0; i < types.length; i++) { + if (include[i]) { + const targetType = getTypeOfPropertyOrIndexSignatureOfType(types[i], propertyName); + if (targetType && related(getDiscriminatingType(), targetType)) { + matched = true; + } + else { + include[i] = Ternary.Maybe; + } + } + } + // Turn each Ternary.Maybe into Ternary.False if there was a match. Otherwise, revert to Ternary.True. + for (let i = 0; i < types.length; i++) { + if (include[i] === Ternary.Maybe) { + include[i] = matched ? Ternary.False : Ternary.True; + } + } + } + const filtered = contains(include, Ternary.False) ? getUnionType(types.filter((_, i) => include[i]), UnionReduction.None) : target; + return filtered.flags & TypeFlags.Never ? target : filtered; + } + + /** + * A type is 'weak' if it is an object type with at least one optional property + * and no required properties, call/construct signatures or index signatures + */ + function isWeakType(type: Type): boolean { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + return resolved.callSignatures.length === 0 && resolved.constructSignatures.length === 0 && resolved.indexInfos.length === 0 && + resolved.properties.length > 0 && every(resolved.properties, p => !!(p.flags & SymbolFlags.Optional)); + } + if (type.flags & TypeFlags.Substitution) { + return isWeakType((type as SubstitutionType).baseType); + } + if (type.flags & TypeFlags.Intersection) { + return every((type as IntersectionType).types, isWeakType); + } + return false; + } + + function hasCommonProperties(source: Type, target: Type, isComparingJsxAttributes: boolean) { + for (const prop of getPropertiesOfType(source)) { + if (isKnownProperty(target, prop.escapedName, isComparingJsxAttributes)) { + return true; + } + } + return false; + } + + function getVariances(type: GenericType): VarianceFlags[] { + // Arrays and tuples are known to be covariant, no need to spend time computing this. + return type === globalArrayType || type === globalReadonlyArrayType || type.objectFlags & ObjectFlags.Tuple ? + arrayVariances : + getVariancesWorker(type.symbol, type.typeParameters); + } + + function getAliasVariances(symbol: Symbol) { + return getVariancesWorker(symbol, getSymbolLinks(symbol).typeParameters); + } + + // Return an array containing the variance of each type parameter. The variance is effectively + // a digest of the type comparisons that occur for each type argument when instantiations of the + // generic type are structurally compared. We infer the variance information by comparing + // instantiations of the generic type for type arguments with known relations. The function + // returns the emptyArray singleton when invoked recursively for the given generic type. + function getVariancesWorker(symbol: Symbol, typeParameters: readonly TypeParameter[] = emptyArray): VarianceFlags[] { + const links = getSymbolLinks(symbol); + if (!links.variances) { + tracing?.push(tracing.Phase.CheckTypes, "getVariancesWorker", { arity: typeParameters.length, id: getTypeId(getDeclaredTypeOfSymbol(symbol)) }); + const oldVarianceComputation = inVarianceComputation; + const saveResolutionStart = resolutionStart; + if (!inVarianceComputation) { + inVarianceComputation = true; + resolutionStart = resolutionTargets.length; + } + links.variances = emptyArray; + const variances = []; + for (const tp of typeParameters) { + const modifiers = getTypeParameterModifiers(tp); + let variance = modifiers & ModifierFlags.Out ? + modifiers & ModifierFlags.In ? VarianceFlags.Invariant : VarianceFlags.Covariant : + modifiers & ModifierFlags.In ? VarianceFlags.Contravariant : undefined; + if (variance === undefined) { + let unmeasurable = false; + let unreliable = false; + const oldHandler = outofbandVarianceMarkerHandler; + outofbandVarianceMarkerHandler = onlyUnreliable => onlyUnreliable ? unreliable = true : unmeasurable = true; + // We first compare instantiations where the type parameter is replaced with + // marker types that have a known subtype relationship. From this we can infer + // invariance, covariance, contravariance or bivariance. + const typeWithSuper = createMarkerType(symbol, tp, markerSuperType); + const typeWithSub = createMarkerType(symbol, tp, markerSubType); + variance = (isTypeAssignableTo(typeWithSub, typeWithSuper) ? VarianceFlags.Covariant : 0) | + (isTypeAssignableTo(typeWithSuper, typeWithSub) ? VarianceFlags.Contravariant : 0); + // If the instantiations appear to be related bivariantly it may be because the + // type parameter is independent (i.e. it isn't witnessed anywhere in the generic + // type). To determine this we compare instantiations where the type parameter is + // replaced with marker types that are known to be unrelated. + if (variance === VarianceFlags.Bivariant && isTypeAssignableTo(createMarkerType(symbol, tp, markerOtherType), typeWithSuper)) { + variance = VarianceFlags.Independent; + } + outofbandVarianceMarkerHandler = oldHandler; + if (unmeasurable || unreliable) { + if (unmeasurable) { + variance |= VarianceFlags.Unmeasurable; + } + if (unreliable) { + variance |= VarianceFlags.Unreliable; + } + } + } + variances.push(variance); + } + if (!oldVarianceComputation) { + inVarianceComputation = false; + resolutionStart = saveResolutionStart; + } + links.variances = variances; + tracing?.pop({ variances: variances.map(Debug.formatVariance) }); + } + return links.variances; + } + + function createMarkerType(symbol: Symbol, source: TypeParameter, target: Type) { + const mapper = makeUnaryTypeMapper(source, target); + const type = getDeclaredTypeOfSymbol(symbol); + if (isErrorType(type)) { + return type; + } + const result = symbol.flags & SymbolFlags.TypeAlias ? + getTypeAliasInstantiation(symbol, instantiateTypes(getSymbolLinks(symbol).typeParameters!, mapper)) : + createTypeReference(type as GenericType, instantiateTypes((type as GenericType).typeParameters, mapper)); + markerTypes.add(getTypeId(result)); + return result; + } + + function isMarkerType(type: Type) { + return markerTypes.has(getTypeId(type)); + } + + function getTypeParameterModifiers(tp: TypeParameter): ModifierFlags { + return reduceLeft(tp.symbol?.declarations, (modifiers, d) => modifiers | getEffectiveModifierFlags(d), ModifierFlags.None) & (ModifierFlags.In | ModifierFlags.Out | ModifierFlags.Const); + } + + // Return true if the given type reference has a 'void' type argument for a covariant type parameter. + // See comment at call in recursiveTypeRelatedTo for when this case matters. + function hasCovariantVoidArgument(typeArguments: readonly Type[], variances: VarianceFlags[]): boolean { + for (let i = 0; i < variances.length; i++) { + if ((variances[i] & VarianceFlags.VarianceMask) === VarianceFlags.Covariant && typeArguments[i].flags & TypeFlags.Void) { + return true; + } + } + return false; + } + + function isUnconstrainedTypeParameter(type: Type) { + return type.flags & TypeFlags.TypeParameter && !getConstraintOfTypeParameter(type as TypeParameter); + } + + function isNonDeferredTypeReference(type: Type): type is TypeReference { + return !!(getObjectFlags(type) & ObjectFlags.Reference) && !(type as TypeReference).node; + } + + function isTypeReferenceWithGenericArguments(type: Type): boolean { + return isNonDeferredTypeReference(type) && some(getTypeArguments(type), t => !!(t.flags & TypeFlags.TypeParameter) || isTypeReferenceWithGenericArguments(t)); + } + + function getGenericTypeReferenceRelationKey(source: TypeReference, target: TypeReference, postFix: string, ignoreConstraints: boolean) { + const typeParameters: Type[] = []; + let constraintMarker = ""; + const sourceId = getTypeReferenceId(source, 0); + const targetId = getTypeReferenceId(target, 0); + return `${constraintMarker}${sourceId},${targetId}${postFix}`; + // getTypeReferenceId(A) returns "111=0-12=1" + // where A.id=111 and number.id=12 + function getTypeReferenceId(type: TypeReference, depth = 0) { + let result = "" + type.target.id; + for (const t of getTypeArguments(type)) { + if (t.flags & TypeFlags.TypeParameter) { + if (ignoreConstraints || isUnconstrainedTypeParameter(t)) { + let index = typeParameters.indexOf(t); + if (index < 0) { + index = typeParameters.length; + typeParameters.push(t); + } + result += "=" + index; + continue; + } + // We mark type references that reference constrained type parameters such that we know to obtain + // and look for a "broadest equivalent key" in the cache. + constraintMarker = "*"; + } + else if (depth < 4 && isTypeReferenceWithGenericArguments(t)) { + result += "<" + getTypeReferenceId(t as TypeReference, depth + 1) + ">"; + continue; + } + result += "-" + t.id; + } + return result; + } + } + + /** + * To improve caching, the relation key for two generic types uses the target's id plus ids of the type parameters. + * For other cases, the types ids are used. + */ + function getRelationKey(source: Type, target: Type, intersectionState: IntersectionState, relation: Map, ignoreConstraints: boolean) { + if (relation === identityRelation && source.id > target.id) { + const temp = source; + source = target; + target = temp; + } + const postFix = intersectionState ? ":" + intersectionState : ""; + return isTypeReferenceWithGenericArguments(source) && isTypeReferenceWithGenericArguments(target) ? + getGenericTypeReferenceRelationKey(source as TypeReference, target as TypeReference, postFix, ignoreConstraints) : + `${source.id},${target.id}${postFix}`; + } + + // Invoke the callback for each underlying property symbol of the given symbol and return the first + // value that isn't undefined. + function forEachProperty(prop: Symbol, callback: (p: Symbol) => T): T | undefined { + if (getCheckFlags(prop) & CheckFlags.Synthetic) { + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.Synthetic + for (const t of (prop as TransientSymbol).links.containingType!.types) { + const p = getPropertyOfType(t, prop.escapedName); + const result = p && forEachProperty(p, callback); + if (result) { + return result; + } + } + return undefined; + } + return callback(prop); + } + + // Return the declaring class type of a property or undefined if property not declared in class + function getDeclaringClass(prop: Symbol) { + return prop.parent && prop.parent.flags & SymbolFlags.Class ? getDeclaredTypeOfSymbol(getParentOfSymbol(prop)!) as InterfaceType : undefined; + } + + // Return the inherited type of the given property or undefined if property doesn't exist in a base class. + function getTypeOfPropertyInBaseClass(property: Symbol) { + const classType = getDeclaringClass(property); + const baseClassType = classType && getBaseTypes(classType)[0]; + return baseClassType && getTypeOfPropertyOfType(baseClassType, property.escapedName); + } + + // Return true if some underlying source property is declared in a class that derives + // from the given base class. + function isPropertyInClassDerivedFrom(prop: Symbol, baseClass: Type | undefined) { + return forEachProperty(prop, sp => { + const sourceClass = getDeclaringClass(sp); + return sourceClass ? hasBaseType(sourceClass, baseClass) : false; + }); + } + + // Return true if source property is a valid override of protected parts of target property. + function isValidOverrideOf(sourceProp: Symbol, targetProp: Symbol) { + return !forEachProperty(targetProp, tp => + getDeclarationModifierFlagsFromSymbol(tp) & ModifierFlags.Protected ? + !isPropertyInClassDerivedFrom(sourceProp, getDeclaringClass(tp)) : false); + } + + // Return true if the given class derives from each of the declaring classes of the protected + // constituents of the given property. + function isClassDerivedFromDeclaringClasses(checkClass: T, prop: Symbol, writing: boolean) { + return forEachProperty(prop, p => + getDeclarationModifierFlagsFromSymbol(p, writing) & ModifierFlags.Protected ? + !hasBaseType(checkClass, getDeclaringClass(p)) : false) ? undefined : checkClass; + } + + // Return true if the given type is deeply nested. We consider this to be the case when the given stack contains + // maxDepth or more occurrences of types with the same recursion identity as the given type. The recursion identity + // provides a shared identity for type instantiations that repeat in some (possibly infinite) pattern. For example, + // in `type Deep = { next: Deep> }`, repeatedly referencing the `next` property leads to an infinite + // sequence of ever deeper instantiations with the same recursion identity (in this case the symbol associated with + // the object type literal). + // A homomorphic mapped type is considered deeply nested if its target type is deeply nested, and an intersection is + // considered deeply nested if any constituent of the intersection is deeply nested. + // It is possible, though highly unlikely, for the deeply nested check to be true in a situation where a chain of + // instantiations is not infinitely expanding. Effectively, we will generate a false positive when two types are + // structurally equal to at least maxDepth levels, but unequal at some level beyond that. + function isDeeplyNestedType(type: Type, stack: Type[], depth: number, maxDepth = 3): boolean { + if (depth >= maxDepth) { + if ((getObjectFlags(type) & ObjectFlags.InstantiatedMapped) === ObjectFlags.InstantiatedMapped) { + type = getMappedTargetWithSymbol(type); + } + if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, t => isDeeplyNestedType(t, stack, depth, maxDepth)); + } + const identity = getRecursionIdentity(type); + let count = 0; + let lastTypeId = 0; + for (let i = 0; i < depth; i++) { + const t = stack[i]; + if (hasMatchingRecursionIdentity(t, identity)) { + // We only count occurrences with a higher type id than the previous occurrence, since higher + // type ids are an indicator of newer instantiations caused by recursion. + if (t.id >= lastTypeId) { + count++; + if (count >= maxDepth) { + return true; + } + } + lastTypeId = t.id; + } + } + } + return false; + } + + // Unwrap nested homomorphic mapped types and return the deepest target type that has a symbol. This better + // preserves unique type identities for mapped types applied to explicitly written object literals. For example + // in `Mapped<{ x: Mapped<{ x: Mapped<{ x: string }>}>}>`, each of the mapped type applications will have a + // unique recursion identity (that of their target object type literal) and thus avoid appearing deeply nested. + function getMappedTargetWithSymbol(type: Type) { + let target; + while ( + (getObjectFlags(type) & ObjectFlags.InstantiatedMapped) === ObjectFlags.InstantiatedMapped && + (target = getModifiersTypeFromMappedType(type as MappedType)) && + (target.symbol || target.flags & TypeFlags.Intersection && some((target as IntersectionType).types, t => !!t.symbol)) + ) { + type = target; + } + return type; + } + + function hasMatchingRecursionIdentity(type: Type, identity: object): boolean { + if ((getObjectFlags(type) & ObjectFlags.InstantiatedMapped) === ObjectFlags.InstantiatedMapped) { + type = getMappedTargetWithSymbol(type); + } + if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, t => hasMatchingRecursionIdentity(t, identity)); + } + return getRecursionIdentity(type) === identity; + } + + // The recursion identity of a type is an object identity that is shared among multiple instantiations of the type. + // We track recursion identities in order to identify deeply nested and possibly infinite type instantiations with + // the same origin. For example, when type parameters are in scope in an object type such as { x: T }, all + // instantiations of that type have the same recursion identity. The default recursion identity is the object + // identity of the type, meaning that every type is unique. Generally, types with constituents that could circularly + // reference the type have a recursion identity that differs from the object identity. + function getRecursionIdentity(type: Type): object { + // Object and array literals are known not to contain recursive references and don't need a recursion identity. + if (type.flags & TypeFlags.Object && !isObjectOrArrayLiteralType(type)) { + if (getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).node) { + // Deferred type references are tracked through their associated AST node. This gives us finer + // granularity than using their associated target because each manifest type reference has a + // unique AST node. + return (type as TypeReference).node!; + } + if (type.symbol && !(getObjectFlags(type) & ObjectFlags.Anonymous && type.symbol.flags & SymbolFlags.Class)) { + // We track object types that have a symbol by that symbol (representing the origin of the type), but + // exclude the static side of a class since it shares its symbol with the instance side. + return type.symbol; + } + if (isTupleType(type)) { + return type.target; + } + } + if (type.flags & TypeFlags.TypeParameter) { + // We use the symbol of the type parameter such that all "fresh" instantiations of that type parameter + // have the same recursion identity. + return type.symbol; + } + if (type.flags & TypeFlags.IndexedAccess) { + // Identity is the leftmost object type in a chain of indexed accesses, eg, in A[P1][P2][P3] it is A. + do { + type = (type as IndexedAccessType).objectType; + } + while (type.flags & TypeFlags.IndexedAccess); + return type; + } + if (type.flags & TypeFlags.Conditional) { + // The root object represents the origin of the conditional type + return (type as ConditionalType).root; + } + return type; + } + + function isPropertyIdenticalTo(sourceProp: Symbol, targetProp: Symbol): boolean { + return compareProperties(sourceProp, targetProp, compareTypesIdentical) !== Ternary.False; + } + + function compareProperties(sourceProp: Symbol, targetProp: Symbol, compareTypes: (source: Type, target: Type) => Ternary): Ternary { + // Two members are considered identical when + // - they are public properties with identical names, optionality, and types, + // - they are private or protected properties originating in the same declaration and having identical types + if (sourceProp === targetProp) { + return Ternary.True; + } + const sourcePropAccessibility = getDeclarationModifierFlagsFromSymbol(sourceProp) & ModifierFlags.NonPublicAccessibilityModifier; + const targetPropAccessibility = getDeclarationModifierFlagsFromSymbol(targetProp) & ModifierFlags.NonPublicAccessibilityModifier; + if (sourcePropAccessibility !== targetPropAccessibility) { + return Ternary.False; + } + if (sourcePropAccessibility) { + if (getTargetSymbol(sourceProp) !== getTargetSymbol(targetProp)) { + return Ternary.False; + } + } + else { + if ((sourceProp.flags & SymbolFlags.Optional) !== (targetProp.flags & SymbolFlags.Optional)) { + return Ternary.False; + } + } + if (isReadonlySymbol(sourceProp) !== isReadonlySymbol(targetProp)) { + return Ternary.False; + } + return compareTypes(getTypeOfSymbol(sourceProp), getTypeOfSymbol(targetProp)); + } + + function isMatchingSignature(source: Signature, target: Signature, partialMatch: boolean) { + const sourceParameterCount = getParameterCount(source); + const targetParameterCount = getParameterCount(target); + const sourceMinArgumentCount = getMinArgumentCount(source); + const targetMinArgumentCount = getMinArgumentCount(target); + const sourceHasRestParameter = hasEffectiveRestParameter(source); + const targetHasRestParameter = hasEffectiveRestParameter(target); + // A source signature matches a target signature if the two signatures have the same number of required, + // optional, and rest parameters. + if ( + sourceParameterCount === targetParameterCount && + sourceMinArgumentCount === targetMinArgumentCount && + sourceHasRestParameter === targetHasRestParameter + ) { + return true; + } + // A source signature partially matches a target signature if the target signature has no fewer required + // parameters + if (partialMatch && sourceMinArgumentCount <= targetMinArgumentCount) { + return true; + } + return false; + } + + /** + * See signatureRelatedTo, compareSignaturesIdentical + */ + function compareSignaturesIdentical(source: Signature, target: Signature, partialMatch: boolean, ignoreThisTypes: boolean, ignoreReturnTypes: boolean, compareTypes: (s: Type, t: Type) => Ternary): Ternary { + // TODO (drosen): De-duplicate code between related functions. + if (source === target) { + return Ternary.True; + } + if (!(isMatchingSignature(source, target, partialMatch))) { + return Ternary.False; + } + // Check that the two signatures have the same number of type parameters. + if (length(source.typeParameters) !== length(target.typeParameters)) { + return Ternary.False; + } + // Check that type parameter constraints and defaults match. If they do, instantiate the source + // signature with the type parameters of the target signature and continue the comparison. + if (target.typeParameters) { + const mapper = createTypeMapper(source.typeParameters!, target.typeParameters); + for (let i = 0; i < target.typeParameters.length; i++) { + const s = source.typeParameters![i]; + const t = target.typeParameters[i]; + if ( + !(s === t || compareTypes(instantiateType(getConstraintFromTypeParameter(s), mapper) || unknownType, getConstraintFromTypeParameter(t) || unknownType) && + compareTypes(instantiateType(getDefaultFromTypeParameter(s), mapper) || unknownType, getDefaultFromTypeParameter(t) || unknownType)) + ) { + return Ternary.False; + } + } + source = instantiateSignature(source, mapper, /*eraseTypeParameters*/ true); + } + let result = Ternary.True; + if (!ignoreThisTypes) { + const sourceThisType = getThisTypeOfSignature(source); + if (sourceThisType) { + const targetThisType = getThisTypeOfSignature(target); + if (targetThisType) { + const related = compareTypes(sourceThisType, targetThisType); + if (!related) { + return Ternary.False; + } + result &= related; + } + } + } + const targetLen = getParameterCount(target); + for (let i = 0; i < targetLen; i++) { + const s = getTypeAtPosition(source, i); + const t = getTypeAtPosition(target, i); + const related = compareTypes(t, s); + if (!related) { + return Ternary.False; + } + result &= related; + } + if (!ignoreReturnTypes) { + const sourceTypePredicate = getTypePredicateOfSignature(source); + const targetTypePredicate = getTypePredicateOfSignature(target); + result &= sourceTypePredicate || targetTypePredicate ? + compareTypePredicatesIdentical(sourceTypePredicate, targetTypePredicate, compareTypes) : + compareTypes(getReturnTypeOfSignature(source), getReturnTypeOfSignature(target)); + } + return result; + } + + function compareTypePredicatesIdentical(source: TypePredicate | undefined, target: TypePredicate | undefined, compareTypes: (s: Type, t: Type) => Ternary): Ternary { + return !(source && target && typePredicateKindsMatch(source, target)) ? Ternary.False : + source.type === target.type ? Ternary.True : + source.type && target.type ? compareTypes(source.type, target.type) : + Ternary.False; + } + + function literalTypesWithSameBaseType(types: Type[]): boolean { + let commonBaseType: Type | undefined; + for (const t of types) { + if (!(t.flags & TypeFlags.Never)) { + const baseType = getBaseTypeOfLiteralType(t); + commonBaseType ??= baseType; + if (baseType === t || baseType !== commonBaseType) { + return false; + } + } + } + return true; + } + + function getCombinedTypeFlags(types: Type[]): TypeFlags { + return reduceLeft(types, (flags, t) => flags | (t.flags & TypeFlags.Union ? getCombinedTypeFlags((t as UnionType).types) : t.flags), 0 as TypeFlags); + } + + function getCommonSupertype(types: Type[]): Type { + if (types.length === 1) { + return types[0]; + } + // Remove nullable types from each of the candidates. + const primaryTypes = strictNullChecks ? sameMap(types, t => filterType(t, u => !(u.flags & TypeFlags.Nullable))) : types; + // When the candidate types are all literal types with the same base type, return a union + // of those literal types. Otherwise, return the leftmost type for which no type to the + // right is a supertype. + const superTypeOrUnion = literalTypesWithSameBaseType(primaryTypes) ? + getUnionType(primaryTypes) : + reduceLeft(primaryTypes, (s, t) => isTypeSubtypeOf(s, t) ? t : s)!; + // Add any nullable types that occurred in the candidates back to the result. + return primaryTypes === types ? superTypeOrUnion : getNullableType(superTypeOrUnion, getCombinedTypeFlags(types) & TypeFlags.Nullable); + } + + // Return the leftmost type for which no type to the right is a subtype. + function getCommonSubtype(types: Type[]) { + return reduceLeft(types, (s, t) => isTypeSubtypeOf(t, s) ? t : s)!; + } + + function isArrayType(type: Type): type is TypeReference { + return !!(getObjectFlags(type) & ObjectFlags.Reference) && ((type as TypeReference).target === globalArrayType || (type as TypeReference).target === globalReadonlyArrayType); + } + + function isReadonlyArrayType(type: Type): boolean { + return !!(getObjectFlags(type) & ObjectFlags.Reference) && (type as TypeReference).target === globalReadonlyArrayType; + } + + function isArrayOrTupleType(type: Type): type is TypeReference { + return isArrayType(type) || isTupleType(type); + } + + function isMutableArrayOrTuple(type: Type): boolean { + return isArrayType(type) && !isReadonlyArrayType(type) || isTupleType(type) && !type.target.readonly; + } + + function getElementTypeOfArrayType(type: Type): Type | undefined { + return isArrayType(type) ? getTypeArguments(type)[0] : undefined; + } + + function isArrayLikeType(type: Type): boolean { + // A type is array-like if it is a reference to the global Array or global ReadonlyArray type, + // or if it is not the undefined or null type and if it is assignable to ReadonlyArray + return isArrayType(type) || !(type.flags & TypeFlags.Nullable) && isTypeAssignableTo(type, anyReadonlyArrayType); + } + + function isMutableArrayLikeType(type: Type): boolean { + // A type is mutable-array-like if it is a reference to the global Array type, or if it is not the + // any, undefined or null type and if it is assignable to Array + return isMutableArrayOrTuple(type) || !(type.flags & (TypeFlags.Any | TypeFlags.Nullable)) && isTypeAssignableTo(type, anyArrayType); + } + + function getSingleBaseForNonAugmentingSubtype(type: Type) { + if (!(getObjectFlags(type) & ObjectFlags.Reference) || !(getObjectFlags((type as TypeReference).target) & ObjectFlags.ClassOrInterface)) { + return undefined; + } + if (getObjectFlags(type) & ObjectFlags.IdenticalBaseTypeCalculated) { + return getObjectFlags(type) & ObjectFlags.IdenticalBaseTypeExists ? (type as TypeReference).cachedEquivalentBaseType : undefined; + } + (type as TypeReference).objectFlags |= ObjectFlags.IdenticalBaseTypeCalculated; + const target = (type as TypeReference).target as InterfaceType; + if (getObjectFlags(target) & ObjectFlags.Class) { + const baseTypeNode = getBaseTypeNodeOfClass(target); + // A base type expression may circularly reference the class itself (e.g. as an argument to function call), so we only + // check for base types specified as simple qualified names. + if (baseTypeNode && baseTypeNode.expression.kind !== SyntaxKind.Identifier && baseTypeNode.expression.kind !== SyntaxKind.PropertyAccessExpression) { + return undefined; + } + } + const bases = getBaseTypes(target); + if (bases.length !== 1) { + return undefined; + } + if (getMembersOfSymbol(type.symbol).size) { + return undefined; // If the interface has any members, they may subtype members in the base, so we should do a full structural comparison + } + let instantiatedBase = !length(target.typeParameters) ? bases[0] : instantiateType(bases[0], createTypeMapper(target.typeParameters!, getTypeArguments(type as TypeReference).slice(0, target.typeParameters!.length))); + if (length(getTypeArguments(type as TypeReference)) > length(target.typeParameters)) { + instantiatedBase = getTypeWithThisArgument(instantiatedBase, last(getTypeArguments(type as TypeReference))); + } + (type as TypeReference).objectFlags |= ObjectFlags.IdenticalBaseTypeExists; + return (type as TypeReference).cachedEquivalentBaseType = instantiatedBase; + } + + function isEmptyLiteralType(type: Type): boolean { + return strictNullChecks ? type === implicitNeverType : type === undefinedWideningType; + } + + function isEmptyArrayLiteralType(type: Type): boolean { + const elementType = getElementTypeOfArrayType(type); + return !!elementType && isEmptyLiteralType(elementType); + } + + function isTupleLikeType(type: Type): boolean { + let lengthType; + return isTupleType(type) || + !!getPropertyOfType(type, "0" as __String) || + isArrayLikeType(type) && !!(lengthType = getTypeOfPropertyOfType(type, "length" as __String)) && everyType(lengthType, t => !!(t.flags & TypeFlags.NumberLiteral)); + } + + function isArrayOrTupleLikeType(type: Type): boolean { + return isArrayLikeType(type) || isTupleLikeType(type); + } + + function getTupleElementType(type: Type, index: number) { + const propType = getTypeOfPropertyOfType(type, "" + index as __String); + if (propType) { + return propType; + } + if (everyType(type, isTupleType)) { + return getTupleElementTypeOutOfStartCount(type, index, compilerOptions.noUncheckedIndexedAccess ? undefinedType : undefined); + } + return undefined; + } + + function isNeitherUnitTypeNorNever(type: Type): boolean { + return !(type.flags & (TypeFlags.Unit | TypeFlags.Never)); + } + + function isUnitType(type: Type): boolean { + return !!(type.flags & TypeFlags.Unit); + } + + function isUnitLikeType(type: Type): boolean { + // Intersections that reduce to 'never' (e.g. 'T & null' where 'T extends {}') are not unit types. + const t = getBaseConstraintOrType(type); + // Scan intersections such that tagged literal types are considered unit types. + return t.flags & TypeFlags.Intersection ? some((t as IntersectionType).types, isUnitType) : isUnitType(t); + } + + function extractUnitType(type: Type) { + return type.flags & TypeFlags.Intersection ? find((type as IntersectionType).types, isUnitType) || type : type; + } + + function isLiteralType(type: Type): boolean { + return type.flags & TypeFlags.Boolean ? true : + type.flags & TypeFlags.Union ? type.flags & TypeFlags.EnumLiteral ? true : every((type as UnionType).types, isUnitType) : + isUnitType(type); + } + + function getBaseTypeOfLiteralType(type: Type): Type { + return type.flags & TypeFlags.EnumLike ? getBaseTypeOfEnumLikeType(type as LiteralType) : + type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? stringType : + type.flags & TypeFlags.NumberLiteral ? numberType : + type.flags & TypeFlags.BigIntLiteral ? bigintType : + type.flags & TypeFlags.BooleanLiteral ? booleanType : + type.flags & TypeFlags.Union ? getBaseTypeOfLiteralTypeUnion(type as UnionType) : + type; + } + + function getBaseTypeOfLiteralTypeUnion(type: UnionType) { + const key = `B${getTypeId(type)}`; + return getCachedType(key) ?? setCachedType(key, mapType(type, getBaseTypeOfLiteralType)); + } + + // This like getBaseTypeOfLiteralType, but instead treats enum literals as strings/numbers instead + // of returning their enum base type (which depends on the types of other literals in the enum). + function getBaseTypeOfLiteralTypeForComparison(type: Type): Type { + return type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? stringType : + type.flags & (TypeFlags.NumberLiteral | TypeFlags.Enum) ? numberType : + type.flags & TypeFlags.BigIntLiteral ? bigintType : + type.flags & TypeFlags.BooleanLiteral ? booleanType : + type.flags & TypeFlags.Union ? mapType(type, getBaseTypeOfLiteralTypeForComparison) : + type; + } + + function getWidenedLiteralType(type: Type): Type { + return type.flags & TypeFlags.EnumLike && isFreshLiteralType(type) ? getBaseTypeOfEnumLikeType(type as LiteralType) : + type.flags & TypeFlags.StringLiteral && isFreshLiteralType(type) ? stringType : + type.flags & TypeFlags.NumberLiteral && isFreshLiteralType(type) ? numberType : + type.flags & TypeFlags.BigIntLiteral && isFreshLiteralType(type) ? bigintType : + type.flags & TypeFlags.BooleanLiteral && isFreshLiteralType(type) ? booleanType : + type.flags & TypeFlags.Union ? mapType(type as UnionType, getWidenedLiteralType) : + type; + } + + function getWidenedUniqueESSymbolType(type: Type): Type { + return type.flags & TypeFlags.UniqueESSymbol ? esSymbolType : + type.flags & TypeFlags.Union ? mapType(type as UnionType, getWidenedUniqueESSymbolType) : + type; + } + + function getWidenedLiteralLikeTypeForContextualType(type: Type, contextualType: Type | undefined) { + if (!isLiteralOfContextualType(type, contextualType)) { + type = getWidenedUniqueESSymbolType(getWidenedLiteralType(type)); + } + return getRegularTypeOfLiteralType(type); + } + + function getWidenedLiteralLikeTypeForContextualReturnTypeIfNeeded(type: Type | undefined, contextualSignatureReturnType: Type | undefined, isAsync: boolean) { + if (type && isUnitType(type)) { + const contextualType = !contextualSignatureReturnType ? undefined : + isAsync ? getPromisedTypeOfPromise(contextualSignatureReturnType) : + contextualSignatureReturnType; + type = getWidenedLiteralLikeTypeForContextualType(type, contextualType); + } + return type; + } + + function getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(type: Type | undefined, contextualSignatureReturnType: Type | undefined, kind: IterationTypeKind, isAsyncGenerator: boolean) { + if (type && isUnitType(type)) { + const contextualType = !contextualSignatureReturnType ? undefined : + getIterationTypeOfGeneratorFunctionReturnType(kind, contextualSignatureReturnType, isAsyncGenerator); + type = getWidenedLiteralLikeTypeForContextualType(type, contextualType); + } + return type; + } + + /** + * Check if a Type was written as a tuple type literal. + * Prefer using isTupleLikeType() unless the use of `elementTypes`/`getTypeArguments` is required. + */ + function isTupleType(type: Type): type is TupleTypeReference { + return !!(getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).target.objectFlags & ObjectFlags.Tuple); + } + + function isGenericTupleType(type: Type): type is TupleTypeReference { + return isTupleType(type) && !!(type.target.combinedFlags & ElementFlags.Variadic); + } + + function isSingleElementGenericTupleType(type: Type): type is TupleTypeReference { + return isGenericTupleType(type) && type.target.elementFlags.length === 1; + } + + function getRestTypeOfTupleType(type: TupleTypeReference) { + return getElementTypeOfSliceOfTupleType(type, type.target.fixedLength); + } + + function getTupleElementTypeOutOfStartCount(type: Type, index: number, undefinedOrMissingType: Type | undefined) { + return mapType(type, t => { + const tupleType = t as TupleTypeReference; + const restType = getRestTypeOfTupleType(tupleType); + if (!restType) { + return undefinedType; + } + if (undefinedOrMissingType && index >= getTotalFixedElementCount(tupleType.target)) { + return getUnionType([restType, undefinedOrMissingType]); + } + return restType; + }); + } + + function getRestArrayTypeOfTupleType(type: TupleTypeReference) { + const restType = getRestTypeOfTupleType(type); + return restType && createArrayType(restType); + } + + function getElementTypeOfSliceOfTupleType(type: TupleTypeReference, index: number, endSkipCount = 0, writing = false, noReductions = false) { + const length = getTypeReferenceArity(type) - endSkipCount; + if (index < length) { + const typeArguments = getTypeArguments(type); + const elementTypes: Type[] = []; + for (let i = index; i < length; i++) { + const t = typeArguments[i]; + elementTypes.push(type.target.elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessType(t, numberType) : t); + } + return writing ? getIntersectionType(elementTypes) : getUnionType(elementTypes, noReductions ? UnionReduction.None : UnionReduction.Literal); + } + return undefined; + } + + function isTupleTypeStructureMatching(t1: TupleTypeReference, t2: TupleTypeReference) { + return getTypeReferenceArity(t1) === getTypeReferenceArity(t2) && + every(t1.target.elementFlags, (f, i) => (f & ElementFlags.Variable) === (t2.target.elementFlags[i] & ElementFlags.Variable)); + } + + function isZeroBigInt({ value }: BigIntLiteralType) { + return value.base10Value === "0"; + } + + function removeDefinitelyFalsyTypes(type: Type): Type { + return filterType(type, t => hasTypeFacts(t, TypeFacts.Truthy)); + } + + function extractDefinitelyFalsyTypes(type: Type): Type { + return mapType(type, getDefinitelyFalsyPartOfType); + } + + function getDefinitelyFalsyPartOfType(type: Type): Type { + return type.flags & TypeFlags.String ? emptyStringType : + type.flags & TypeFlags.Number ? zeroType : + type.flags & TypeFlags.BigInt ? zeroBigIntType : + type === regularFalseType || + type === falseType || + type.flags & (TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Null | TypeFlags.AnyOrUnknown) || + type.flags & TypeFlags.StringLiteral && (type as StringLiteralType).value === "" || + type.flags & TypeFlags.NumberLiteral && (type as NumberLiteralType).value === 0 || + type.flags & TypeFlags.BigIntLiteral && isZeroBigInt(type as BigIntLiteralType) ? type : + neverType; + } + + /** + * Add undefined or null or both to a type if they are missing. + * @param type - type to add undefined and/or null to if not present + * @param flags - Either TypeFlags.Undefined or TypeFlags.Null, or both + */ + function getNullableType(type: Type, flags: TypeFlags): Type { + const missing = (flags & ~type.flags) & (TypeFlags.Undefined | TypeFlags.Null); + return missing === 0 ? type : + missing === TypeFlags.Undefined ? getUnionType([type, undefinedType]) : + missing === TypeFlags.Null ? getUnionType([type, nullType]) : + getUnionType([type, undefinedType, nullType]); + } + + function getOptionalType(type: Type, isProperty = false): Type { + Debug.assert(strictNullChecks); + const missingOrUndefined = isProperty ? undefinedOrMissingType : undefinedType; + return type === missingOrUndefined || type.flags & TypeFlags.Union && (type as UnionType).types[0] === missingOrUndefined ? type : getUnionType([type, missingOrUndefined]); + } + + function getGlobalNonNullableTypeInstantiation(type: Type) { + if (!deferredGlobalNonNullableTypeAlias) { + deferredGlobalNonNullableTypeAlias = getGlobalSymbol("NonNullable" as __String, SymbolFlags.TypeAlias, /*diagnostic*/ undefined) || unknownSymbol; + } + return deferredGlobalNonNullableTypeAlias !== unknownSymbol ? + getTypeAliasInstantiation(deferredGlobalNonNullableTypeAlias, [type]) : + getIntersectionType([type, emptyObjectType]); + } + + function getNonNullableType(type: Type): Type { + return strictNullChecks ? getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; + } + + function addOptionalTypeMarker(type: Type) { + return strictNullChecks ? getUnionType([type, optionalType]) : type; + } + + function removeOptionalTypeMarker(type: Type): Type { + return strictNullChecks ? removeType(type, optionalType) : type; + } + + function propagateOptionalTypeMarker(type: Type, node: OptionalChain, wasOptional: boolean) { + return wasOptional ? isOutermostOptionalChain(node) ? getOptionalType(type) : addOptionalTypeMarker(type) : type; + } + + function getOptionalExpressionType(exprType: Type, expression: Expression) { + return isExpressionOfOptionalChainRoot(expression) ? getNonNullableType(exprType) : + isOptionalChain(expression) ? removeOptionalTypeMarker(exprType) : + exprType; + } + + function removeMissingType(type: Type, isOptional: boolean) { + return exactOptionalPropertyTypes && isOptional ? removeType(type, missingType) : type; + } + + function containsMissingType(type: Type) { + return type === missingType || !!(type.flags & TypeFlags.Union) && (type as UnionType).types[0] === missingType; + } + + function removeMissingOrUndefinedType(type: Type): Type { + return exactOptionalPropertyTypes ? removeType(type, missingType) : getTypeWithFacts(type, TypeFacts.NEUndefined); + } + + /** + * Is source potentially coercible to target type under `==`. + * Assumes that `source` is a constituent of a union, hence + * the boolean literal flag on the LHS, but not on the RHS. + * + * This does not fully replicate the semantics of `==`. The + * intention is to catch cases that are clearly not right. + * + * Comparing (string | number) to number should not remove the + * string element. + * + * Comparing (string | number) to 1 will remove the string + * element, though this is not sound. This is a pragmatic + * choice. + * + * @see narrowTypeByEquality + * + * @param source + * @param target + */ + function isCoercibleUnderDoubleEquals(source: Type, target: Type): boolean { + return ((source.flags & (TypeFlags.Number | TypeFlags.String | TypeFlags.BooleanLiteral)) !== 0) + && ((target.flags & (TypeFlags.Number | TypeFlags.String | TypeFlags.Boolean)) !== 0); + } + + /** + * Return true if type was inferred from an object literal, written as an object type literal, or is the shape of a module + * with no call or construct signatures. + */ + function isObjectTypeWithInferableIndex(type: Type): boolean { + const objectFlags = getObjectFlags(type); + return type.flags & TypeFlags.Intersection + ? every((type as IntersectionType).types, isObjectTypeWithInferableIndex) + : !!( + type.symbol + && (type.symbol.flags & (SymbolFlags.ObjectLiteral | SymbolFlags.TypeLiteral | SymbolFlags.Enum | SymbolFlags.ValueModule)) !== 0 + && !(type.symbol.flags & SymbolFlags.Class) + && !typeHasCallOrConstructSignatures(type) + ) || !!( + objectFlags & ObjectFlags.ObjectRestType + ) || !!(objectFlags & ObjectFlags.ReverseMapped && isObjectTypeWithInferableIndex((type as ReverseMappedType).source)); + } + + function createSymbolWithType(source: Symbol, type: Type | undefined) { + const symbol = createSymbol(source.flags, source.escapedName, getCheckFlags(source) & CheckFlags.Readonly); + symbol.declarations = source.declarations; + symbol.parent = source.parent; + symbol.links.type = type; + symbol.links.target = source; + if (source.valueDeclaration) { + symbol.valueDeclaration = source.valueDeclaration; + } + const nameType = getSymbolLinks(source).nameType; + if (nameType) { + symbol.links.nameType = nameType; + } + return symbol; + } + + function transformTypeOfMembers(type: Type, f: (propertyType: Type) => Type) { + const members = createSymbolTable(); + for (const property of getPropertiesOfObjectType(type)) { + const original = getTypeOfSymbol(property); + const updated = f(original); + members.set(property.escapedName, updated === original ? property : createSymbolWithType(property, updated)); + } + return members; + } + + /** + * If the the provided object literal is subject to the excess properties check, + * create a new that is exempt. Recursively mark object literal members as exempt. + * Leave signatures alone since they are not subject to the check. + */ + function getRegularTypeOfObjectLiteral(type: Type): Type { + if (!(isObjectLiteralType(type) && getObjectFlags(type) & ObjectFlags.FreshLiteral)) { + return type; + } + const regularType = (type as FreshObjectLiteralType).regularType; + if (regularType) { + return regularType; + } + + const resolved = type as ResolvedType; + const members = transformTypeOfMembers(type, getRegularTypeOfObjectLiteral); + const regularNew = createAnonymousType(resolved.symbol, members, resolved.callSignatures, resolved.constructSignatures, resolved.indexInfos); + regularNew.flags = resolved.flags; + regularNew.objectFlags |= resolved.objectFlags & ~ObjectFlags.FreshLiteral; + (type as FreshObjectLiteralType).regularType = regularNew; + return regularNew; + } + + function createWideningContext(parent: WideningContext | undefined, propertyName: __String | undefined, siblings: Type[] | undefined): WideningContext { + return { parent, propertyName, siblings, resolvedProperties: undefined }; + } + + function getSiblingsOfContext(context: WideningContext): Type[] { + if (!context.siblings) { + const siblings: Type[] = []; + for (const type of getSiblingsOfContext(context.parent!)) { + if (isObjectLiteralType(type)) { + const prop = getPropertyOfObjectType(type, context.propertyName!); + if (prop) { + forEachType(getTypeOfSymbol(prop), t => { + siblings.push(t); + }); + } + } + } + context.siblings = siblings; + } + return context.siblings; + } + + function getPropertiesOfContext(context: WideningContext): Symbol[] { + if (!context.resolvedProperties) { + const names = new Map<__String, Symbol>(); + for (const t of getSiblingsOfContext(context)) { + if (isObjectLiteralType(t) && !(getObjectFlags(t) & ObjectFlags.ContainsSpread)) { + for (const prop of getPropertiesOfType(t)) { + names.set(prop.escapedName, prop); + } + } + } + context.resolvedProperties = arrayFrom(names.values()); + } + return context.resolvedProperties; + } + + function getWidenedProperty(prop: Symbol, context: WideningContext | undefined): Symbol { + if (!(prop.flags & SymbolFlags.Property)) { + // Since get accessors already widen their return value there is no need to + // widen accessor based properties here. + return prop; + } + const original = getTypeOfSymbol(prop); + const propContext = context && createWideningContext(context, prop.escapedName, /*siblings*/ undefined); + const widened = getWidenedTypeWithContext(original, propContext); + return widened === original ? prop : createSymbolWithType(prop, widened); + } + + function getUndefinedProperty(prop: Symbol) { + const cached = undefinedProperties.get(prop.escapedName); + if (cached) { + return cached; + } + const result = createSymbolWithType(prop, undefinedOrMissingType); + result.flags |= SymbolFlags.Optional; + undefinedProperties.set(prop.escapedName, result); + return result; + } + + function getWidenedTypeOfObjectLiteral(type: Type, context: WideningContext | undefined): Type { + const members = createSymbolTable(); + for (const prop of getPropertiesOfObjectType(type)) { + members.set(prop.escapedName, getWidenedProperty(prop, context)); + } + if (context) { + for (const prop of getPropertiesOfContext(context)) { + if (!members.has(prop.escapedName)) { + members.set(prop.escapedName, getUndefinedProperty(prop)); + } + } + } + const result = createAnonymousType(type.symbol, members, emptyArray, emptyArray, sameMap(getIndexInfosOfType(type), info => createIndexInfo(info.keyType, getWidenedType(info.type), info.isReadonly))); + result.objectFlags |= getObjectFlags(type) & (ObjectFlags.JSLiteral | ObjectFlags.NonInferrableType); // Retain js literal flag through widening + return result; + } + + function getWidenedType(type: Type) { + return getWidenedTypeWithContext(type, /*context*/ undefined); + } + + function getWidenedTypeWithContext(type: Type, context: WideningContext | undefined): Type { + if (getObjectFlags(type) & ObjectFlags.RequiresWidening) { + if (context === undefined && type.widened) { + return type.widened; + } + let result: Type | undefined; + if (type.flags & (TypeFlags.Any | TypeFlags.Nullable)) { + result = anyType; + } + else if (isObjectLiteralType(type)) { + result = getWidenedTypeOfObjectLiteral(type, context); + } + else if (type.flags & TypeFlags.Union) { + const unionContext = context || createWideningContext(/*parent*/ undefined, /*propertyName*/ undefined, (type as UnionType).types); + const widenedTypes = sameMap((type as UnionType).types, t => t.flags & TypeFlags.Nullable ? t : getWidenedTypeWithContext(t, unionContext)); + // Widening an empty object literal transitions from a highly restrictive type to + // a highly inclusive one. For that reason we perform subtype reduction here if the + // union includes empty object types (e.g. reducing {} | string to just {}). + result = getUnionType(widenedTypes, some(widenedTypes, isEmptyObjectType) ? UnionReduction.Subtype : UnionReduction.Literal); + } + else if (type.flags & TypeFlags.Intersection) { + result = getIntersectionType(sameMap((type as IntersectionType).types, getWidenedType)); + } + else if (isArrayOrTupleType(type)) { + result = createTypeReference(type.target, sameMap(getTypeArguments(type), getWidenedType)); + } + if (result && context === undefined) { + type.widened = result; + } + return result || type; + } + return type; + } + + /** + * Reports implicit any errors that occur as a result of widening 'null' and 'undefined' + * to 'any'. A call to reportWideningErrorsInType is normally accompanied by a call to + * getWidenedType. But in some cases getWidenedType is called without reporting errors + * (type argument inference is an example). + * + * The return value indicates whether an error was in fact reported. The particular circumstances + * are on a best effort basis. Currently, if the null or undefined that causes widening is inside + * an object literal property (arbitrarily deeply), this function reports an error. If no error is + * reported, reportImplicitAnyError is a suitable fallback to report a general error. + */ + function reportWideningErrorsInType(type: Type): boolean { + let errorReported = false; + if (getObjectFlags(type) & ObjectFlags.ContainsWideningType) { + if (type.flags & TypeFlags.Union) { + if (some((type as UnionType).types, isEmptyObjectType)) { + errorReported = true; + } + else { + for (const t of (type as UnionType).types) { + errorReported ||= reportWideningErrorsInType(t); + } + } + } + else if (isArrayOrTupleType(type)) { + for (const t of getTypeArguments(type)) { + errorReported ||= reportWideningErrorsInType(t); + } + } + else if (isObjectLiteralType(type)) { + for (const p of getPropertiesOfObjectType(type)) { + const t = getTypeOfSymbol(p); + if (getObjectFlags(t) & ObjectFlags.ContainsWideningType) { + errorReported = reportWideningErrorsInType(t); + if (!errorReported) { + // we need to account for property types coming from object literal type normalization in unions + const valueDeclaration = p.declarations?.find(d => d.symbol.valueDeclaration?.parent === type.symbol.valueDeclaration); + if (valueDeclaration) { + error(valueDeclaration, Diagnostics.Object_literal_s_property_0_implicitly_has_an_1_type, symbolToString(p), typeToString(getWidenedType(t))); + errorReported = true; + } + } + } + } + } + } + return errorReported; + } + + function reportImplicitAny(declaration: Declaration, type: Type, wideningKind?: WideningKind) { + const typeAsString = typeToString(getWidenedType(type)); + if (isInJSFile(declaration) && !isCheckJsEnabledForFile(getSourceFileOfNode(declaration), compilerOptions)) { + // Only report implicit any errors/suggestions in TS and ts-check JS files + return; + } + let diagnostic: DiagnosticMessage; + switch (declaration.kind) { + case SyntaxKind.BinaryExpression: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + diagnostic = noImplicitAny ? Diagnostics.Member_0_implicitly_has_an_1_type : Diagnostics.Member_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; + break; + case SyntaxKind.Parameter: + const param = declaration as ParameterDeclaration; + if (isIdentifier(param.name)) { + const originalKeywordKind = identifierToKeywordKind(param.name); + if ( + (isCallSignatureDeclaration(param.parent) || isMethodSignature(param.parent) || isFunctionTypeNode(param.parent)) && + param.parent.parameters.includes(param) && + (resolveName(param, param.name.escapedText, SymbolFlags.Type, /*nameNotFoundMessage*/ undefined, /*isUse*/ true) || + originalKeywordKind && isTypeNodeKind(originalKeywordKind)) + ) { + const newName = "arg" + param.parent.parameters.indexOf(param); + const typeName = declarationNameToString(param.name) + (param.dotDotDotToken ? "[]" : ""); + errorOrSuggestion(noImplicitAny, declaration, Diagnostics.Parameter_has_a_name_but_no_type_Did_you_mean_0_Colon_1, newName, typeName); + return; + } + } + diagnostic = (declaration as ParameterDeclaration).dotDotDotToken ? + noImplicitAny ? Diagnostics.Rest_parameter_0_implicitly_has_an_any_type : Diagnostics.Rest_parameter_0_implicitly_has_an_any_type_but_a_better_type_may_be_inferred_from_usage : + noImplicitAny ? Diagnostics.Parameter_0_implicitly_has_an_1_type : Diagnostics.Parameter_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; + break; + case SyntaxKind.BindingElement: + diagnostic = Diagnostics.Binding_element_0_implicitly_has_an_1_type; + if (!noImplicitAny) { + // Don't issue a suggestion for binding elements since the codefix doesn't yet support them. + return; + } + break; + case SyntaxKind.JSDocFunctionType: + error(declaration, Diagnostics.Function_type_which_lacks_return_type_annotation_implicitly_has_an_0_return_type, typeAsString); + return; + case SyntaxKind.JSDocSignature: + if (noImplicitAny && isJSDocOverloadTag(declaration.parent)) { + error(declaration.parent.tagName, Diagnostics.This_overload_implicitly_returns_the_type_0_because_it_lacks_a_return_type_annotation, typeAsString); + } + return; + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + if (noImplicitAny && !(declaration as NamedDeclaration).name) { + if (wideningKind === WideningKind.GeneratorYield) { + error(declaration, Diagnostics.Generator_implicitly_has_yield_type_0_because_it_does_not_yield_any_values_Consider_supplying_a_return_type_annotation, typeAsString); + } + else { + error(declaration, Diagnostics.Function_expression_which_lacks_return_type_annotation_implicitly_has_an_0_return_type, typeAsString); + } + return; + } + diagnostic = !noImplicitAny ? Diagnostics._0_implicitly_has_an_1_return_type_but_a_better_type_may_be_inferred_from_usage : + wideningKind === WideningKind.GeneratorYield ? Diagnostics._0_which_lacks_return_type_annotation_implicitly_has_an_1_yield_type : + Diagnostics._0_which_lacks_return_type_annotation_implicitly_has_an_1_return_type; + break; + case SyntaxKind.MappedType: + if (noImplicitAny) { + error(declaration, Diagnostics.Mapped_object_type_implicitly_has_an_any_template_type); + } + return; + default: + diagnostic = noImplicitAny ? Diagnostics.Variable_0_implicitly_has_an_1_type : Diagnostics.Variable_0_implicitly_has_an_1_type_but_a_better_type_may_be_inferred_from_usage; + } + errorOrSuggestion(noImplicitAny, declaration, diagnostic, declarationNameToString(getNameOfDeclaration(declaration)), typeAsString); + } + + function reportErrorsFromWidening(declaration: Declaration, type: Type, wideningKind?: WideningKind) { + addLazyDiagnostic(() => { + if (noImplicitAny && getObjectFlags(type) & ObjectFlags.ContainsWideningType && (!wideningKind || !getContextualSignatureForFunctionLikeDeclaration(declaration as FunctionLikeDeclaration))) { + // Report implicit any error within type if possible, otherwise report error on declaration + if (!reportWideningErrorsInType(type)) { + reportImplicitAny(declaration, type, wideningKind); + } + } + }); + } + + function applyToParameterTypes(source: Signature, target: Signature, callback: (s: Type, t: Type) => void) { + const sourceCount = getParameterCount(source); + const targetCount = getParameterCount(target); + const sourceRestType = getEffectiveRestType(source); + const targetRestType = getEffectiveRestType(target); + const targetNonRestCount = targetRestType ? targetCount - 1 : targetCount; + const paramCount = sourceRestType ? targetNonRestCount : Math.min(sourceCount, targetNonRestCount); + const sourceThisType = getThisTypeOfSignature(source); + if (sourceThisType) { + const targetThisType = getThisTypeOfSignature(target); + if (targetThisType) { + callback(sourceThisType, targetThisType); + } + } + for (let i = 0; i < paramCount; i++) { + callback(getTypeAtPosition(source, i), getTypeAtPosition(target, i)); + } + if (targetRestType) { + callback(getRestTypeAtPosition(source, paramCount, /*readonly*/ isConstTypeVariable(targetRestType) && !someType(targetRestType, isMutableArrayLikeType)), targetRestType); + } + } + + function applyToReturnTypes(source: Signature, target: Signature, callback: (s: Type, t: Type) => void) { + const targetTypePredicate = getTypePredicateOfSignature(target); + if (targetTypePredicate) { + const sourceTypePredicate = getTypePredicateOfSignature(source); + if (sourceTypePredicate && typePredicateKindsMatch(sourceTypePredicate, targetTypePredicate) && sourceTypePredicate.type && targetTypePredicate.type) { + callback(sourceTypePredicate.type, targetTypePredicate.type); + return; + } + } + const targetReturnType = getReturnTypeOfSignature(target); + if (couldContainTypeVariables(targetReturnType)) { + callback(getReturnTypeOfSignature(source), targetReturnType); + } + } + + function createInferenceContext(typeParameters: readonly TypeParameter[], signature: Signature | undefined, flags: InferenceFlags, compareTypes?: TypeComparer): InferenceContext { + return createInferenceContextWorker(typeParameters.map(createInferenceInfo), signature, flags, compareTypes || compareTypesAssignable); + } + + function cloneInferenceContext(context: T, extraFlags: InferenceFlags = 0): InferenceContext | T & undefined { + return context && createInferenceContextWorker(map(context.inferences, cloneInferenceInfo), context.signature, context.flags | extraFlags, context.compareTypes); + } + + function createInferenceContextWorker(inferences: InferenceInfo[], signature: Signature | undefined, flags: InferenceFlags, compareTypes: TypeComparer): InferenceContext { + const context: InferenceContext = { + inferences, + signature, + flags, + compareTypes, + mapper: reportUnmeasurableMapper, // initialize to a noop mapper so the context object is available, but the underlying object shape is right upon construction + nonFixingMapper: reportUnmeasurableMapper, + }; + context.mapper = makeFixingMapperForContext(context); + context.nonFixingMapper = makeNonFixingMapperForContext(context); + return context; + } + + function makeFixingMapperForContext(context: InferenceContext) { + return makeDeferredTypeMapper( + map(context.inferences, i => i.typeParameter), + map(context.inferences, (inference, i) => () => { + if (!inference.isFixed) { + // Before we commit to a particular inference (and thus lock out any further inferences), + // we infer from any intra-expression inference sites we have collected. + inferFromIntraExpressionSites(context); + clearCachedInferences(context.inferences); + inference.isFixed = true; + } + return getInferredType(context, i); + }), + ); + } + + function makeNonFixingMapperForContext(context: InferenceContext) { + return makeDeferredTypeMapper( + map(context.inferences, i => i.typeParameter), + map(context.inferences, (_, i) => () => { + return getInferredType(context, i); + }), + ); + } + + function clearCachedInferences(inferences: InferenceInfo[]) { + for (const inference of inferences) { + if (!inference.isFixed) { + inference.inferredType = undefined; + } + } + } + + function addIntraExpressionInferenceSite(context: InferenceContext, node: Expression | MethodDeclaration, type: Type) { + (context.intraExpressionInferenceSites ??= []).push({ node, type }); + } + + // We collect intra-expression inference sites within object and array literals to handle cases where + // inferred types flow between context sensitive element expressions. For example: + // + // declare function foo(arg: [(n: number) => T, (x: T) => void]): void; + // foo([_a => 0, n => n.toFixed()]); + // + // Above, both arrow functions in the tuple argument are context sensitive, thus both are omitted from the + // pass that collects inferences from the non-context sensitive parts of the arguments. In the subsequent + // pass where nothing is omitted, we need to commit to an inference for T in order to contextually type the + // parameter in the second arrow function, but we want to first infer from the return type of the first + // arrow function. This happens automatically when the arrow functions are discrete arguments (because we + // infer from each argument before processing the next), but when the arrow functions are elements of an + // object or array literal, we need to perform intra-expression inferences early. + function inferFromIntraExpressionSites(context: InferenceContext) { + if (context.intraExpressionInferenceSites) { + for (const { node, type } of context.intraExpressionInferenceSites) { + const contextualType = node.kind === SyntaxKind.MethodDeclaration ? + getContextualTypeForObjectLiteralMethod(node as MethodDeclaration, ContextFlags.NoConstraints) : + getContextualType(node, ContextFlags.NoConstraints); + if (contextualType) { + inferTypes(context.inferences, type, contextualType); + } + } + context.intraExpressionInferenceSites = undefined; + } + } + + function createInferenceInfo(typeParameter: TypeParameter): InferenceInfo { + return { + typeParameter, + candidates: undefined, + contraCandidates: undefined, + inferredType: undefined, + priority: undefined, + topLevel: true, + isFixed: false, + impliedArity: undefined, + }; + } + + function cloneInferenceInfo(inference: InferenceInfo): InferenceInfo { + return { + typeParameter: inference.typeParameter, + candidates: inference.candidates && inference.candidates.slice(), + contraCandidates: inference.contraCandidates && inference.contraCandidates.slice(), + inferredType: inference.inferredType, + priority: inference.priority, + topLevel: inference.topLevel, + isFixed: inference.isFixed, + impliedArity: inference.impliedArity, + }; + } + + function cloneInferredPartOfContext(context: InferenceContext): InferenceContext | undefined { + const inferences = filter(context.inferences, hasInferenceCandidates); + return inferences.length ? + createInferenceContextWorker(map(inferences, cloneInferenceInfo), context.signature, context.flags, context.compareTypes) : + undefined; + } + + function getMapperFromContext(context: T): TypeMapper | T & undefined { + return context && context.mapper; + } + + // Return true if the given type could possibly reference a type parameter for which + // we perform type inference (i.e. a type parameter of a generic function). We cache + // results for union and intersection types for performance reasons. + function couldContainTypeVariables(type: Type): boolean { + const objectFlags = getObjectFlags(type); + if (objectFlags & ObjectFlags.CouldContainTypeVariablesComputed) { + return !!(objectFlags & ObjectFlags.CouldContainTypeVariables); + } + const result = !!(type.flags & TypeFlags.Instantiable || + type.flags & TypeFlags.Object && !isNonGenericTopLevelType(type) && ( + objectFlags & ObjectFlags.Reference && ((type as TypeReference).node || some(getTypeArguments(type as TypeReference), couldContainTypeVariables)) || + objectFlags & ObjectFlags.SingleSignatureType && !!length((type as SingleSignatureType).outerTypeParameters) || + objectFlags & ObjectFlags.Anonymous && type.symbol && type.symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.TypeLiteral | SymbolFlags.ObjectLiteral) && type.symbol.declarations || + objectFlags & (ObjectFlags.Mapped | ObjectFlags.ReverseMapped | ObjectFlags.ObjectRestType | ObjectFlags.InstantiationExpressionType) + ) || + type.flags & TypeFlags.UnionOrIntersection && !(type.flags & TypeFlags.EnumLiteral) && !isNonGenericTopLevelType(type) && some((type as UnionOrIntersectionType).types, couldContainTypeVariables)); + if (type.flags & TypeFlags.ObjectFlagsType) { + (type as ObjectFlagsType).objectFlags |= ObjectFlags.CouldContainTypeVariablesComputed | (result ? ObjectFlags.CouldContainTypeVariables : 0); + } + return result; + } + + function isNonGenericTopLevelType(type: Type) { + if (type.aliasSymbol && !type.aliasTypeArguments) { + const declaration = getDeclarationOfKind(type.aliasSymbol, SyntaxKind.TypeAliasDeclaration); + return !!(declaration && findAncestor(declaration.parent, n => n.kind === SyntaxKind.SourceFile ? true : n.kind === SyntaxKind.ModuleDeclaration ? false : "quit")); + } + return false; + } + + function isTypeParameterAtTopLevel(type: Type, tp: TypeParameter, depth = 0): boolean { + return !!(type === tp || + type.flags & TypeFlags.UnionOrIntersection && some((type as UnionOrIntersectionType).types, t => isTypeParameterAtTopLevel(t, tp, depth)) || + depth < 3 && type.flags & TypeFlags.Conditional && ( + isTypeParameterAtTopLevel(getTrueTypeFromConditionalType(type as ConditionalType), tp, depth + 1) || + isTypeParameterAtTopLevel(getFalseTypeFromConditionalType(type as ConditionalType), tp, depth + 1) + )); + } + + function isTypeParameterAtTopLevelInReturnType(signature: Signature, typeParameter: TypeParameter) { + const typePredicate = getTypePredicateOfSignature(signature); + return typePredicate ? !!typePredicate.type && isTypeParameterAtTopLevel(typePredicate.type, typeParameter) : + isTypeParameterAtTopLevel(getReturnTypeOfSignature(signature), typeParameter); + } + + /** Create an object with properties named in the string literal type. Every property has type `any` */ + function createEmptyObjectTypeFromStringLiteral(type: Type) { + const members = createSymbolTable(); + forEachType(type, t => { + if (!(t.flags & TypeFlags.StringLiteral)) { + return; + } + const name = escapeLeadingUnderscores((t as StringLiteralType).value); + const literalProp = createSymbol(SymbolFlags.Property, name); + literalProp.links.type = anyType; + if (t.symbol) { + literalProp.declarations = t.symbol.declarations; + literalProp.valueDeclaration = t.symbol.valueDeclaration; + } + members.set(name, literalProp); + }); + const indexInfos = type.flags & TypeFlags.String ? [createIndexInfo(stringType, emptyObjectType, /*isReadonly*/ false)] : emptyArray; + return createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, indexInfos); + } + + /** + * Infer a suitable input type for a homomorphic mapped type { [P in keyof T]: X }. We construct + * an object type with the same set of properties as the source type, where the type of each + * property is computed by inferring from the source property type to X for the type + * variable T[P] (i.e. we treat the type T[P] as the type variable we're inferring for). + */ + function inferTypeForHomomorphicMappedType(source: Type, target: MappedType, constraint: IndexType): Type | undefined { + const cacheKey = source.id + "," + target.id + "," + constraint.id; + if (reverseMappedCache.has(cacheKey)) { + return reverseMappedCache.get(cacheKey); + } + const type = createReverseMappedType(source, target, constraint); + reverseMappedCache.set(cacheKey, type); + return type; + } + + // We consider a type to be partially inferable if it isn't marked non-inferable or if it is + // an object literal type with at least one property of an inferable type. For example, an object + // literal { a: 123, b: x => true } is marked non-inferable because it contains a context sensitive + // arrow function, but is considered partially inferable because property 'a' has an inferable type. + function isPartiallyInferableType(type: Type): boolean { + return !(getObjectFlags(type) & ObjectFlags.NonInferrableType) || + isObjectLiteralType(type) && some(getPropertiesOfType(type), prop => isPartiallyInferableType(getTypeOfSymbol(prop))) || + isTupleType(type) && some(getElementTypes(type), isPartiallyInferableType); + } + + function createReverseMappedType(source: Type, target: MappedType, constraint: IndexType) { + // We consider a source type reverse mappable if it has a string index signature or if + // it has one or more properties and is of a partially inferable type. + if (!(getIndexInfoOfType(source, stringType) || getPropertiesOfType(source).length !== 0 && isPartiallyInferableType(source))) { + return undefined; + } + // For arrays and tuples we infer new arrays and tuples where the reverse mapping has been + // applied to the element type(s). + if (isArrayType(source)) { + const elementType = inferReverseMappedType(getTypeArguments(source)[0], target, constraint); + if (!elementType) { + return undefined; + } + return createArrayType(elementType, isReadonlyArrayType(source)); + } + if (isTupleType(source)) { + const elementTypes = map(getElementTypes(source), t => inferReverseMappedType(t, target, constraint)); + if (!every(elementTypes, (t): t is Type => !!t)) { + return undefined; + } + const elementFlags = getMappedTypeModifiers(target) & MappedTypeModifiers.IncludeOptional ? + sameMap(source.target.elementFlags, f => f & ElementFlags.Optional ? ElementFlags.Required : f) : + source.target.elementFlags; + return createTupleType(elementTypes, elementFlags, source.target.readonly, source.target.labeledElementDeclarations); + } + // For all other object types we infer a new object type where the reverse mapping has been + // applied to the type of each property. + const reversed = createObjectType(ObjectFlags.ReverseMapped | ObjectFlags.Anonymous, /*symbol*/ undefined) as ReverseMappedType; + reversed.source = source; + reversed.mappedType = target; + reversed.constraintType = constraint; + return reversed; + } + + function getTypeOfReverseMappedSymbol(symbol: ReverseMappedSymbol): Type { + const links = getSymbolLinks(symbol); + if (!links.type) { + links.type = inferReverseMappedType(symbol.links.propertyType, symbol.links.mappedType, symbol.links.constraintType) || unknownType; + } + return links.type; + } + + function inferReverseMappedTypeWorker(sourceType: Type, target: MappedType, constraint: IndexType): Type { + const typeParameter = getIndexedAccessType(constraint.type, getTypeParameterFromMappedType(target)) as TypeParameter; + const templateType = getTemplateTypeFromMappedType(target); + const inference = createInferenceInfo(typeParameter); + inferTypes([inference], sourceType, templateType); + return getTypeFromInference(inference) || unknownType; + } + + function inferReverseMappedType(source: Type, target: MappedType, constraint: IndexType): Type | undefined { + const cacheKey = source.id + "," + target.id + "," + constraint.id; + if (reverseMappedCache.has(cacheKey)) { + return reverseMappedCache.get(cacheKey) || unknownType; + } + reverseMappedSourceStack.push(source); + reverseMappedTargetStack.push(target); + const saveExpandingFlags = reverseExpandingFlags; + if (isDeeplyNestedType(source, reverseMappedSourceStack, reverseMappedSourceStack.length, 2)) reverseExpandingFlags |= ExpandingFlags.Source; + if (isDeeplyNestedType(target, reverseMappedTargetStack, reverseMappedTargetStack.length, 2)) reverseExpandingFlags |= ExpandingFlags.Target; + let type; + if (reverseExpandingFlags !== ExpandingFlags.Both) { + type = inferReverseMappedTypeWorker(source, target, constraint); + } + reverseMappedSourceStack.pop(); + reverseMappedTargetStack.pop(); + reverseExpandingFlags = saveExpandingFlags; + reverseMappedCache.set(cacheKey, type); + return type; + } + + function* getUnmatchedProperties(source: Type, target: Type, requireOptionalProperties: boolean, matchDiscriminantProperties: boolean): IterableIterator { + const properties = getPropertiesOfType(target); + for (const targetProp of properties) { + // TODO: remove this when we support static private identifier fields and find other solutions to get privateNamesAndStaticFields test to pass + if (isStaticPrivateIdentifierProperty(targetProp)) { + continue; + } + if (requireOptionalProperties || !(targetProp.flags & SymbolFlags.Optional || getCheckFlags(targetProp) & CheckFlags.Partial)) { + const sourceProp = getPropertyOfType(source, targetProp.escapedName); + if (!sourceProp) { + yield targetProp; + } + else if (matchDiscriminantProperties) { + const targetType = getTypeOfSymbol(targetProp); + if (targetType.flags & TypeFlags.Unit) { + const sourceType = getTypeOfSymbol(sourceProp); + if (!(sourceType.flags & TypeFlags.Any || getRegularTypeOfLiteralType(sourceType) === getRegularTypeOfLiteralType(targetType))) { + yield targetProp; + } + } + } + } + } + } + + function getUnmatchedProperty(source: Type, target: Type, requireOptionalProperties: boolean, matchDiscriminantProperties: boolean): Symbol | undefined { + return firstOrUndefinedIterator(getUnmatchedProperties(source, target, requireOptionalProperties, matchDiscriminantProperties)); + } + + function tupleTypesDefinitelyUnrelated(source: TupleTypeReference, target: TupleTypeReference) { + return !(target.target.combinedFlags & ElementFlags.Variadic) && target.target.minLength > source.target.minLength || + !(target.target.combinedFlags & ElementFlags.Variable) && (!!(source.target.combinedFlags & ElementFlags.Variable) || target.target.fixedLength < source.target.fixedLength); + } + + function typesDefinitelyUnrelated(source: Type, target: Type) { + // Two tuple types with incompatible arities are definitely unrelated. + // Two object types that each have a property that is unmatched in the other are definitely unrelated. + return isTupleType(source) && isTupleType(target) ? tupleTypesDefinitelyUnrelated(source, target) : + !!getUnmatchedProperty(source, target, /*requireOptionalProperties*/ false, /*matchDiscriminantProperties*/ true) && + !!getUnmatchedProperty(target, source, /*requireOptionalProperties*/ false, /*matchDiscriminantProperties*/ false); + } + + function getTypeFromInference(inference: InferenceInfo) { + return inference.candidates ? getUnionType(inference.candidates, UnionReduction.Subtype) : + inference.contraCandidates ? getIntersectionType(inference.contraCandidates) : + undefined; + } + + function hasSkipDirectInferenceFlag(node: Node) { + return !!getNodeLinks(node).skipDirectInference; + } + + function isFromInferenceBlockedSource(type: Type) { + return !!(type.symbol && some(type.symbol.declarations, hasSkipDirectInferenceFlag)); + } + + function templateLiteralTypesDefinitelyUnrelated(source: TemplateLiteralType, target: TemplateLiteralType) { + // Two template literal types with diffences in their starting or ending text spans are definitely unrelated. + const sourceStart = source.texts[0]; + const targetStart = target.texts[0]; + const sourceEnd = source.texts[source.texts.length - 1]; + const targetEnd = target.texts[target.texts.length - 1]; + const startLen = Math.min(sourceStart.length, targetStart.length); + const endLen = Math.min(sourceEnd.length, targetEnd.length); + return sourceStart.slice(0, startLen) !== targetStart.slice(0, startLen) || + sourceEnd.slice(sourceEnd.length - endLen) !== targetEnd.slice(targetEnd.length - endLen); + } + + /** + * Tests whether the provided string can be parsed as a number. + * @param s The string to test. + * @param roundTripOnly Indicates the resulting number matches the input when converted back to a string. + */ + function isValidNumberString(s: string, roundTripOnly: boolean): boolean { + if (s === "") return false; + const n = +s; + return isFinite(n) && (!roundTripOnly || "" + n === s); + } + + /** + * @param text a valid bigint string excluding a trailing `n`, but including a possible prefix `-`. Use `isValidBigIntString(text, roundTripOnly)` before calling this function. + */ + function parseBigIntLiteralType(text: string) { + return getBigIntLiteralType(parseValidBigInt(text)); + } + + function isMemberOfStringMapping(source: Type, target: Type): boolean { + if (target.flags & TypeFlags.Any) { + return true; + } + if (target.flags & (TypeFlags.String | TypeFlags.TemplateLiteral)) { + return isTypeAssignableTo(source, target); + } + if (target.flags & TypeFlags.StringMapping) { + // We need to see whether applying the same mappings of the target + // onto the source would produce an identical type *and* that + // it's compatible with the inner-most non-string-mapped type. + // + // The intuition here is that if same mappings don't affect the source at all, + // and the source is compatible with the unmapped target, then they must + // still reside in the same domain. + const mappingStack = []; + while (target.flags & TypeFlags.StringMapping) { + mappingStack.unshift(target.symbol); + target = (target as StringMappingType).type; + } + const mappedSource = reduceLeft(mappingStack, (memo, value) => getStringMappingType(value, memo), source); + return mappedSource === source && isMemberOfStringMapping(source, target); + } + return false; + } + + function isValidTypeForTemplateLiteralPlaceholder(source: Type, target: Type): boolean { + if (target.flags & TypeFlags.Intersection) { + return every((target as IntersectionType).types, t => t === emptyTypeLiteralType || isValidTypeForTemplateLiteralPlaceholder(source, t)); + } + if (target.flags & TypeFlags.String || isTypeAssignableTo(source, target)) { + return true; + } + if (source.flags & TypeFlags.StringLiteral) { + const value = (source as StringLiteralType).value; + return !!(target.flags & TypeFlags.Number && isValidNumberString(value, /*roundTripOnly*/ false) || + target.flags & TypeFlags.BigInt && isValidBigIntString(value, /*roundTripOnly*/ false) || + target.flags & (TypeFlags.BooleanLiteral | TypeFlags.Nullable) && value === (target as IntrinsicType).intrinsicName || + target.flags & TypeFlags.StringMapping && isMemberOfStringMapping(getStringLiteralType(value), target) || + target.flags & TypeFlags.TemplateLiteral && isTypeMatchedByTemplateLiteralType(source, target as TemplateLiteralType)); + } + if (source.flags & TypeFlags.TemplateLiteral) { + const texts = (source as TemplateLiteralType).texts; + return texts.length === 2 && texts[0] === "" && texts[1] === "" && isTypeAssignableTo((source as TemplateLiteralType).types[0], target); + } + return false; + } + + function inferTypesFromTemplateLiteralType(source: Type, target: TemplateLiteralType): Type[] | undefined { + return source.flags & TypeFlags.StringLiteral ? inferFromLiteralPartsToTemplateLiteral([(source as StringLiteralType).value], emptyArray, target) : + source.flags & TypeFlags.TemplateLiteral ? + arraysEqual((source as TemplateLiteralType).texts, target.texts) ? map((source as TemplateLiteralType).types, (s, i) => { + return isTypeAssignableTo(getBaseConstraintOrType(s), getBaseConstraintOrType(target.types[i])) ? s : getStringLikeTypeForType(s); + }) : + inferFromLiteralPartsToTemplateLiteral((source as TemplateLiteralType).texts, (source as TemplateLiteralType).types, target) : + undefined; + } + + function isTypeMatchedByTemplateLiteralType(source: Type, target: TemplateLiteralType): boolean { + const inferences = inferTypesFromTemplateLiteralType(source, target); + return !!inferences && every(inferences, (r, i) => isValidTypeForTemplateLiteralPlaceholder(r, target.types[i])); + } + + function getStringLikeTypeForType(type: Type) { + return type.flags & (TypeFlags.Any | TypeFlags.StringLike) ? type : getTemplateLiteralType(["", ""], [type]); + } + + // This function infers from the text parts and type parts of a source literal to a target template literal. The number + // of text parts is always one more than the number of type parts, and a source string literal is treated as a source + // with one text part and zero type parts. The function returns an array of inferred string or template literal types + // corresponding to the placeholders in the target template literal, or undefined if the source doesn't match the target. + // + // We first check that the starting source text part matches the starting target text part, and that the ending source + // text part ends matches the ending target text part. We then iterate through the remaining target text parts, finding + // a match for each in the source and inferring string or template literal types created from the segments of the source + // that occur between the matches. During this iteration, seg holds the index of the current text part in the sourceTexts + // array and pos holds the current character position in the current text part. + // + // Consider inference from type `<<${string}>.<${number}-${number}>>` to type `<${string}.${string}>`, i.e. + // sourceTexts = ['<<', '>.<', '-', '>>'] + // sourceTypes = [string, number, number] + // target.texts = ['<', '.', '>'] + // We first match '<' in the target to the start of '<<' in the source and '>' in the target to the end of '>>' in + // the source. The first match for the '.' in target occurs at character 1 in the source text part at index 1, and thus + // the first inference is the template literal type `<${string}>`. The remainder of the source makes up the second + // inference, the template literal type `<${number}-${number}>`. + function inferFromLiteralPartsToTemplateLiteral(sourceTexts: readonly string[], sourceTypes: readonly Type[], target: TemplateLiteralType): Type[] | undefined { + const lastSourceIndex = sourceTexts.length - 1; + const sourceStartText = sourceTexts[0]; + const sourceEndText = sourceTexts[lastSourceIndex]; + const targetTexts = target.texts; + const lastTargetIndex = targetTexts.length - 1; + const targetStartText = targetTexts[0]; + const targetEndText = targetTexts[lastTargetIndex]; + if ( + lastSourceIndex === 0 && sourceStartText.length < targetStartText.length + targetEndText.length || + !sourceStartText.startsWith(targetStartText) || !sourceEndText.endsWith(targetEndText) + ) return undefined; + const remainingEndText = sourceEndText.slice(0, sourceEndText.length - targetEndText.length); + const matches: Type[] = []; + let seg = 0; + let pos = targetStartText.length; + for (let i = 1; i < lastTargetIndex; i++) { + const delim = targetTexts[i]; + if (delim.length > 0) { + let s = seg; + let p = pos; + while (true) { + p = getSourceText(s).indexOf(delim, p); + if (p >= 0) break; + s++; + if (s === sourceTexts.length) return undefined; + p = 0; + } + addMatch(s, p); + pos += delim.length; + } + else if (pos < getSourceText(seg).length) { + addMatch(seg, pos + 1); + } + else if (seg < lastSourceIndex) { + addMatch(seg + 1, 0); + } + else { + return undefined; + } + } + addMatch(lastSourceIndex, getSourceText(lastSourceIndex).length); + return matches; + function getSourceText(index: number) { + return index < lastSourceIndex ? sourceTexts[index] : remainingEndText; + } + function addMatch(s: number, p: number) { + const matchType = s === seg ? + getStringLiteralType(getSourceText(s).slice(pos, p)) : + getTemplateLiteralType( + [sourceTexts[seg].slice(pos), ...sourceTexts.slice(seg + 1, s), getSourceText(s).slice(0, p)], + sourceTypes.slice(seg, s), + ); + matches.push(matchType); + seg = s; + pos = p; + } + } + + /** + * @returns `true` if `type` has the shape `[T[0]]` where `T` is `typeParameter` + */ + function isTupleOfSelf(typeParameter: TypeParameter, type: Type) { + return isTupleType(type) && getTupleElementType(type, 0) === getIndexedAccessType(typeParameter, getNumberLiteralType(0)) && !getTypeOfPropertyOfType(type, "1" as __String); + } + + function inferTypes(inferences: InferenceInfo[], originalSource: Type, originalTarget: Type, priority = InferencePriority.None, contravariant = false) { + let bivariant = false; + let propagationType: Type; + let inferencePriority: number = InferencePriority.MaxValue; + let visited: Map; + let sourceStack: Type[]; + let targetStack: Type[]; + let expandingFlags = ExpandingFlags.None; + inferFromTypes(originalSource, originalTarget); + + function inferFromTypes(source: Type, target: Type): void { + if (!couldContainTypeVariables(target) || isNoInferType(target)) { + return; + } + if (source === wildcardType || source === blockedStringType) { + // We are inferring from an 'any' type. We want to infer this type for every type parameter + // referenced in the target type, so we record it as the propagation type and infer from the + // target to itself. Then, as we find candidates we substitute the propagation type. + const savePropagationType = propagationType; + propagationType = source; + inferFromTypes(target, target); + propagationType = savePropagationType; + return; + } + if (source.aliasSymbol && source.aliasSymbol === target.aliasSymbol) { + if (source.aliasTypeArguments) { + // Source and target are types originating in the same generic type alias declaration. + // Simply infer from source type arguments to target type arguments, with defaults applied. + const params = getSymbolLinks(source.aliasSymbol).typeParameters!; + const minParams = getMinTypeArgumentCount(params); + const sourceTypes = fillMissingTypeArguments(source.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + const targetTypes = fillMissingTypeArguments(target.aliasTypeArguments, params, minParams, isInJSFile(source.aliasSymbol.valueDeclaration)); + inferFromTypeArguments(sourceTypes, targetTypes!, getAliasVariances(source.aliasSymbol)); + } + // And if there weren't any type arguments, there's no reason to run inference as the types must be the same. + return; + } + if (source === target && source.flags & TypeFlags.UnionOrIntersection) { + // When source and target are the same union or intersection type, just relate each constituent + // type to itself. + for (const t of (source as UnionOrIntersectionType).types) { + inferFromTypes(t, t); + } + return; + } + if (target.flags & TypeFlags.Union) { + // First, infer between identically matching source and target constituents and remove the + // matching types. + const [tempSources, tempTargets] = inferFromMatchingTypes(source.flags & TypeFlags.Union ? (source as UnionType).types : [source], (target as UnionType).types, isTypeOrBaseIdenticalTo); + // Next, infer between closely matching source and target constituents and remove + // the matching types. Types closely match when they are instantiations of the same + // object type or instantiations of the same type alias. + const [sources, targets] = inferFromMatchingTypes(tempSources, tempTargets, isTypeCloselyMatchedBy); + if (targets.length === 0) { + return; + } + target = getUnionType(targets); + if (sources.length === 0) { + // All source constituents have been matched and there is nothing further to infer from. + // However, simply making no inferences is undesirable because it could ultimately mean + // inferring a type parameter constraint. Instead, make a lower priority inference from + // the full source to whatever remains in the target. For example, when inferring from + // string to 'string | T', make a lower priority inference of string for T. + inferWithPriority(source, target, InferencePriority.NakedTypeVariable); + return; + } + source = getUnionType(sources); + } + else if (target.flags & TypeFlags.Intersection && !every((target as IntersectionType).types, isNonGenericObjectType)) { + // We reduce intersection types unless they're simple combinations of object types. For example, + // when inferring from 'string[] & { extra: any }' to 'string[] & T' we want to remove string[] and + // infer { extra: any } for T. But when inferring to 'string[] & Iterable' we want to keep the + // string[] on the source side and infer string for T. + if (!(source.flags & TypeFlags.Union)) { + // Infer between identically matching source and target constituents and remove the matching types. + const [sources, targets] = inferFromMatchingTypes(source.flags & TypeFlags.Intersection ? (source as IntersectionType).types : [source], (target as IntersectionType).types, isTypeIdenticalTo); + if (sources.length === 0 || targets.length === 0) { + return; + } + source = getIntersectionType(sources); + target = getIntersectionType(targets); + } + } + if (target.flags & (TypeFlags.IndexedAccess | TypeFlags.Substitution)) { + if (isNoInferType(target)) { + return; + } + target = getActualTypeVariable(target); + } + if (target.flags & TypeFlags.TypeVariable) { + // Skip inference if the source is "blocked", which is used by the language service to + // prevent inference on nodes currently being edited. + if (isFromInferenceBlockedSource(source)) { + return; + } + const inference = getInferenceInfoForType(target); + if (inference) { + // If target is a type parameter, make an inference, unless the source type contains + // a "non-inferrable" type. Types with this flag set are markers used to prevent inference. + // + // For example: + // - anyFunctionType is a wildcard type that's used to avoid contextually typing functions; + // it's internal, so should not be exposed to the user by adding it as a candidate. + // - autoType (and autoArrayType) is a special "any" used in control flow; like anyFunctionType, + // it's internal and should not be observable. + // - silentNeverType is returned by getInferredType when instantiating a generic function for + // inference (and a type variable has no mapping). + // + // This flag is infectious; if we produce Box (where never is silentNeverType), Box is + // also non-inferrable. + // + // As a special case, also ignore nonInferrableAnyType, which is a special form of the any type + // used as a stand-in for binding elements when they are being inferred. + if (getObjectFlags(source) & ObjectFlags.NonInferrableType || source === nonInferrableAnyType) { + return; + } + if (!inference.isFixed) { + const candidate = propagationType || source; + if (candidate === blockedStringType) { + return; + } + if (inference.priority === undefined || priority < inference.priority) { + inference.candidates = undefined; + inference.contraCandidates = undefined; + inference.topLevel = true; + inference.priority = priority; + } + if (priority === inference.priority) { + // Inferring A to [A[0]] is a zero information inference (it guarantees A becomes its constraint), but oft arises from generic argument list inferences + // By discarding it early, we can allow more fruitful results to be used instead. + if (isTupleOfSelf(inference.typeParameter, candidate)) { + return; + } + // We make contravariant inferences only if we are in a pure contravariant position, + // i.e. only if we have not descended into a bivariant position. + if (contravariant && !bivariant) { + if (!contains(inference.contraCandidates, candidate)) { + inference.contraCandidates = append(inference.contraCandidates, candidate); + clearCachedInferences(inferences); + } + } + else if (!contains(inference.candidates, candidate)) { + inference.candidates = append(inference.candidates, candidate); + clearCachedInferences(inferences); + } + } + if (!(priority & InferencePriority.ReturnType) && target.flags & TypeFlags.TypeParameter && inference.topLevel && !isTypeParameterAtTopLevel(originalTarget, target as TypeParameter)) { + inference.topLevel = false; + clearCachedInferences(inferences); + } + } + inferencePriority = Math.min(inferencePriority, priority); + return; + } + // Infer to the simplified version of an indexed access, if possible, to (hopefully) expose more bare type parameters to the inference engine + const simplified = getSimplifiedType(target, /*writing*/ false); + if (simplified !== target) { + inferFromTypes(source, simplified); + } + else if (target.flags & TypeFlags.IndexedAccess) { + const indexType = getSimplifiedType((target as IndexedAccessType).indexType, /*writing*/ false); + // Generally simplifications of instantiable indexes are avoided to keep relationship checking correct, however if our target is an access, we can consider + // that key of that access to be "instantiated", since we're looking to find the infernce goal in any way we can. + if (indexType.flags & TypeFlags.Instantiable) { + const simplified = distributeIndexOverObjectType(getSimplifiedType((target as IndexedAccessType).objectType, /*writing*/ false), indexType, /*writing*/ false); + if (simplified && simplified !== target) { + inferFromTypes(source, simplified); + } + } + } + } + if ( + getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && ( + (source as TypeReference).target === (target as TypeReference).target || isArrayType(source) && isArrayType(target) + ) && + !((source as TypeReference).node && (target as TypeReference).node) + ) { + // If source and target are references to the same generic type, infer from type arguments + inferFromTypeArguments(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), getVariances((source as TypeReference).target)); + } + else if (source.flags & TypeFlags.Index && target.flags & TypeFlags.Index) { + inferFromContravariantTypes((source as IndexType).type, (target as IndexType).type); + } + else if ((isLiteralType(source) || source.flags & TypeFlags.String) && target.flags & TypeFlags.Index) { + const empty = createEmptyObjectTypeFromStringLiteral(source); + inferFromContravariantTypesWithPriority(empty, (target as IndexType).type, InferencePriority.LiteralKeyof); + } + else if (source.flags & TypeFlags.IndexedAccess && target.flags & TypeFlags.IndexedAccess) { + inferFromTypes((source as IndexedAccessType).objectType, (target as IndexedAccessType).objectType); + inferFromTypes((source as IndexedAccessType).indexType, (target as IndexedAccessType).indexType); + } + else if (source.flags & TypeFlags.StringMapping && target.flags & TypeFlags.StringMapping) { + if ((source as StringMappingType).symbol === (target as StringMappingType).symbol) { + inferFromTypes((source as StringMappingType).type, (target as StringMappingType).type); + } + } + else if (source.flags & TypeFlags.Substitution) { + inferFromTypes((source as SubstitutionType).baseType, target); + inferWithPriority(getSubstitutionIntersection(source as SubstitutionType), target, InferencePriority.SubstituteSource); // Make substitute inference at a lower priority + } + else if (target.flags & TypeFlags.Conditional) { + invokeOnce(source, target as ConditionalType, inferToConditionalType); + } + else if (target.flags & TypeFlags.UnionOrIntersection) { + inferToMultipleTypes(source, (target as UnionOrIntersectionType).types, target.flags); + } + else if (source.flags & TypeFlags.Union) { + // Source is a union or intersection type, infer from each constituent type + const sourceTypes = (source as UnionOrIntersectionType).types; + for (const sourceType of sourceTypes) { + inferFromTypes(sourceType, target); + } + } + else if (target.flags & TypeFlags.TemplateLiteral) { + inferToTemplateLiteralType(source, target as TemplateLiteralType); + } + else { + source = getReducedType(source); + if (isGenericMappedType(source) && isGenericMappedType(target)) { + invokeOnce(source, target, inferFromGenericMappedTypes); + } + if (!(priority & InferencePriority.NoConstraints && source.flags & (TypeFlags.Intersection | TypeFlags.Instantiable))) { + const apparentSource = getApparentType(source); + // getApparentType can return _any_ type, since an indexed access or conditional may simplify to any other type. + // If that occurs and it doesn't simplify to an object or intersection, we'll need to restart `inferFromTypes` + // with the simplified source. + if (apparentSource !== source && !(apparentSource.flags & (TypeFlags.Object | TypeFlags.Intersection))) { + return inferFromTypes(apparentSource, target); + } + source = apparentSource; + } + if (source.flags & (TypeFlags.Object | TypeFlags.Intersection)) { + invokeOnce(source, target, inferFromObjectTypes); + } + } + } + + function inferWithPriority(source: Type, target: Type, newPriority: InferencePriority) { + const savePriority = priority; + priority |= newPriority; + inferFromTypes(source, target); + priority = savePriority; + } + + function inferFromContravariantTypesWithPriority(source: Type, target: Type, newPriority: InferencePriority) { + const savePriority = priority; + priority |= newPriority; + inferFromContravariantTypes(source, target); + priority = savePriority; + } + + function inferToMultipleTypesWithPriority(source: Type, targets: Type[], targetFlags: TypeFlags, newPriority: InferencePriority) { + const savePriority = priority; + priority |= newPriority; + inferToMultipleTypes(source, targets, targetFlags); + priority = savePriority; + } + + // Ensure an inference action is performed only once for the given source and target types. + // This includes two things: + // Avoiding inferring between the same pair of source and target types, + // and avoiding circularly inferring between source and target types. + // For an example of the last, consider if we are inferring between source type + // `type Deep = { next: Deep> }` and target type `type Loop = { next: Loop }`. + // We would then infer between the types of the `next` property: `Deep>` = `{ next: Deep>> }` and `Loop` = `{ next: Loop }`. + // We will then infer again between the types of the `next` property: + // `Deep>>` and `Loop`, and so on, such that we would be forever inferring + // between instantiations of the same types `Deep` and `Loop`. + // In particular, we would be inferring from increasingly deep instantiations of `Deep` to `Loop`, + // such that we would go on inferring forever, even though we would never infer + // between the same pair of types. + function invokeOnce(source: Source, target: Target, action: (source: Source, target: Target) => void) { + const key = source.id + "," + target.id; + const status = visited && visited.get(key); + if (status !== undefined) { + inferencePriority = Math.min(inferencePriority, status); + return; + } + (visited || (visited = new Map())).set(key, InferencePriority.Circularity); + const saveInferencePriority = inferencePriority; + inferencePriority = InferencePriority.MaxValue; + // We stop inferring and report a circularity if we encounter duplicate recursion identities on both + // the source side and the target side. + const saveExpandingFlags = expandingFlags; + (sourceStack ??= []).push(source); + (targetStack ??= []).push(target); + if (isDeeplyNestedType(source, sourceStack, sourceStack.length, 2)) expandingFlags |= ExpandingFlags.Source; + if (isDeeplyNestedType(target, targetStack, targetStack.length, 2)) expandingFlags |= ExpandingFlags.Target; + if (expandingFlags !== ExpandingFlags.Both) { + action(source, target); + } + else { + inferencePriority = InferencePriority.Circularity; + } + targetStack.pop(); + sourceStack.pop(); + expandingFlags = saveExpandingFlags; + visited.set(key, inferencePriority); + inferencePriority = Math.min(inferencePriority, saveInferencePriority); + } + + function inferFromMatchingTypes(sources: Type[], targets: Type[], matches: (s: Type, t: Type) => boolean): [Type[], Type[]] { + let matchedSources: Type[] | undefined; + let matchedTargets: Type[] | undefined; + for (const t of targets) { + for (const s of sources) { + if (matches(s, t)) { + inferFromTypes(s, t); + matchedSources = appendIfUnique(matchedSources, s); + matchedTargets = appendIfUnique(matchedTargets, t); + } + } + } + return [ + matchedSources ? filter(sources, t => !contains(matchedSources, t)) : sources, + matchedTargets ? filter(targets, t => !contains(matchedTargets, t)) : targets, + ]; + } + + function inferFromTypeArguments(sourceTypes: readonly Type[], targetTypes: readonly Type[], variances: readonly VarianceFlags[]) { + const count = sourceTypes.length < targetTypes.length ? sourceTypes.length : targetTypes.length; + for (let i = 0; i < count; i++) { + if (i < variances.length && (variances[i] & VarianceFlags.VarianceMask) === VarianceFlags.Contravariant) { + inferFromContravariantTypes(sourceTypes[i], targetTypes[i]); + } + else { + inferFromTypes(sourceTypes[i], targetTypes[i]); + } + } + } + + function inferFromContravariantTypes(source: Type, target: Type) { + contravariant = !contravariant; + inferFromTypes(source, target); + contravariant = !contravariant; + } + + function inferFromContravariantTypesIfStrictFunctionTypes(source: Type, target: Type) { + if (strictFunctionTypes || priority & InferencePriority.AlwaysStrict) { + inferFromContravariantTypes(source, target); + } + else { + inferFromTypes(source, target); + } + } + + function getInferenceInfoForType(type: Type) { + if (type.flags & TypeFlags.TypeVariable) { + for (const inference of inferences) { + if (type === inference.typeParameter) { + return inference; + } + } + } + return undefined; + } + + function getSingleTypeVariableFromIntersectionTypes(types: Type[]) { + let typeVariable: Type | undefined; + for (const type of types) { + const t = type.flags & TypeFlags.Intersection && find((type as IntersectionType).types, t => !!getInferenceInfoForType(t)); + if (!t || typeVariable && t !== typeVariable) { + return undefined; + } + typeVariable = t; + } + return typeVariable; + } + + function inferToMultipleTypes(source: Type, targets: Type[], targetFlags: TypeFlags) { + let typeVariableCount = 0; + if (targetFlags & TypeFlags.Union) { + let nakedTypeVariable: Type | undefined; + const sources = source.flags & TypeFlags.Union ? (source as UnionType).types : [source]; + const matched = new Array(sources.length); + let inferenceCircularity = false; + // First infer to types that are not naked type variables. For each source type we + // track whether inferences were made from that particular type to some target with + // equal priority (i.e. of equal quality) to what we would infer for a naked type + // parameter. + for (const t of targets) { + if (getInferenceInfoForType(t)) { + nakedTypeVariable = t; + typeVariableCount++; + } + else { + for (let i = 0; i < sources.length; i++) { + const saveInferencePriority = inferencePriority; + inferencePriority = InferencePriority.MaxValue; + inferFromTypes(sources[i], t); + if (inferencePriority === priority) matched[i] = true; + inferenceCircularity = inferenceCircularity || inferencePriority === InferencePriority.Circularity; + inferencePriority = Math.min(inferencePriority, saveInferencePriority); + } + } + } + if (typeVariableCount === 0) { + // If every target is an intersection of types containing a single naked type variable, + // make a lower priority inference to that type variable. This handles inferring from + // 'A | B' to 'T & (X | Y)' where we want to infer 'A | B' for T. + const intersectionTypeVariable = getSingleTypeVariableFromIntersectionTypes(targets); + if (intersectionTypeVariable) { + inferWithPriority(source, intersectionTypeVariable, InferencePriority.NakedTypeVariable); + } + return; + } + // If the target has a single naked type variable and no inference circularities were + // encountered above (meaning we explored the types fully), create a union of the source + // types from which no inferences have been made so far and infer from that union to the + // naked type variable. + if (typeVariableCount === 1 && !inferenceCircularity) { + const unmatched = flatMap(sources, (s, i) => matched[i] ? undefined : s); + if (unmatched.length) { + inferFromTypes(getUnionType(unmatched), nakedTypeVariable!); + return; + } + } + } + else { + // We infer from types that are not naked type variables first so that inferences we + // make from nested naked type variables and given slightly higher priority by virtue + // of being first in the candidates array. + for (const t of targets) { + if (getInferenceInfoForType(t)) { + typeVariableCount++; + } + else { + inferFromTypes(source, t); + } + } + } + // Inferences directly to naked type variables are given lower priority as they are + // less specific. For example, when inferring from Promise to T | Promise, + // we want to infer string for T, not Promise | string. For intersection types + // we only infer to single naked type variables. + if (targetFlags & TypeFlags.Intersection ? typeVariableCount === 1 : typeVariableCount > 0) { + for (const t of targets) { + if (getInferenceInfoForType(t)) { + inferWithPriority(source, t, InferencePriority.NakedTypeVariable); + } + } + } + } + + function inferToMappedType(source: Type, target: MappedType, constraintType: Type): boolean { + if ((constraintType.flags & TypeFlags.Union) || (constraintType.flags & TypeFlags.Intersection)) { + let result = false; + for (const type of (constraintType as (UnionType | IntersectionType)).types) { + result = inferToMappedType(source, target, type) || result; + } + return result; + } + if (constraintType.flags & TypeFlags.Index) { + // We're inferring from some source type S to a homomorphic mapped type { [P in keyof T]: X }, + // where T is a type variable. Use inferTypeForHomomorphicMappedType to infer a suitable source + // type and then make a secondary inference from that type to T. We make a secondary inference + // such that direct inferences to T get priority over inferences to Partial, for example. + const inference = getInferenceInfoForType((constraintType as IndexType).type); + if (inference && !inference.isFixed && !isFromInferenceBlockedSource(source)) { + const inferredType = inferTypeForHomomorphicMappedType(source, target, constraintType as IndexType); + if (inferredType) { + // We assign a lower priority to inferences made from types containing non-inferrable + // types because we may only have a partial result (i.e. we may have failed to make + // reverse inferences for some properties). + inferWithPriority( + inferredType, + inference.typeParameter, + getObjectFlags(source) & ObjectFlags.NonInferrableType ? + InferencePriority.PartialHomomorphicMappedType : + InferencePriority.HomomorphicMappedType, + ); + } + } + return true; + } + if (constraintType.flags & TypeFlags.TypeParameter) { + // We're inferring from some source type S to a mapped type { [P in K]: X }, where K is a type + // parameter. First infer from 'keyof S' to K. + inferWithPriority(getIndexType(source, /*indexFlags*/ !!source.pattern ? IndexFlags.NoIndexSignatures : IndexFlags.None), constraintType, InferencePriority.MappedTypeConstraint); + // If K is constrained to a type C, also infer to C. Thus, for a mapped type { [P in K]: X }, + // where K extends keyof T, we make the same inferences as for a homomorphic mapped type + // { [P in keyof T]: X }. This enables us to make meaningful inferences when the target is a + // Pick. + const extendedConstraint = getConstraintOfType(constraintType); + if (extendedConstraint && inferToMappedType(source, target, extendedConstraint)) { + return true; + } + // If no inferences can be made to K's constraint, infer from a union of the property types + // in the source to the template type X. + const propTypes = map(getPropertiesOfType(source), getTypeOfSymbol); + const indexTypes = map(getIndexInfosOfType(source), info => info !== enumNumberIndexInfo ? info.type : neverType); + inferFromTypes(getUnionType(concatenate(propTypes, indexTypes)), getTemplateTypeFromMappedType(target)); + return true; + } + return false; + } + + function inferToConditionalType(source: Type, target: ConditionalType) { + if (source.flags & TypeFlags.Conditional) { + inferFromTypes((source as ConditionalType).checkType, target.checkType); + inferFromTypes((source as ConditionalType).extendsType, target.extendsType); + inferFromTypes(getTrueTypeFromConditionalType(source as ConditionalType), getTrueTypeFromConditionalType(target)); + inferFromTypes(getFalseTypeFromConditionalType(source as ConditionalType), getFalseTypeFromConditionalType(target)); + } + else { + const targetTypes = [getTrueTypeFromConditionalType(target), getFalseTypeFromConditionalType(target)]; + inferToMultipleTypesWithPriority(source, targetTypes, target.flags, contravariant ? InferencePriority.ContravariantConditional : 0); + } + } + + function inferToTemplateLiteralType(source: Type, target: TemplateLiteralType) { + const matches = inferTypesFromTemplateLiteralType(source, target); + const types = target.types; + // When the target template literal contains only placeholders (meaning that inference is intended to extract + // single characters and remainder strings) and inference fails to produce matches, we want to infer 'never' for + // each placeholder such that instantiation with the inferred value(s) produces 'never', a type for which an + // assignment check will fail. If we make no inferences, we'll likely end up with the constraint 'string' which, + // upon instantiation, would collapse all the placeholders to just 'string', and an assignment check might + // succeed. That would be a pointless and confusing outcome. + if (matches || every(target.texts, s => s.length === 0)) { + for (let i = 0; i < types.length; i++) { + const source = matches ? matches[i] : neverType; + const target = types[i]; + + // If we are inferring from a string literal type to a type variable whose constraint includes one of the + // allowed template literal placeholder types, infer from a literal type corresponding to the constraint. + if (source.flags & TypeFlags.StringLiteral && target.flags & TypeFlags.TypeVariable) { + const inferenceContext = getInferenceInfoForType(target); + const constraint = inferenceContext ? getBaseConstraintOfType(inferenceContext.typeParameter) : undefined; + if (constraint && !isTypeAny(constraint)) { + const constraintTypes = constraint.flags & TypeFlags.Union ? (constraint as UnionType).types : [constraint]; + let allTypeFlags: TypeFlags = reduceLeft(constraintTypes, (flags, t) => flags | t.flags, 0 as TypeFlags); + + // If the constraint contains `string`, we don't need to look for a more preferred type + if (!(allTypeFlags & TypeFlags.String)) { + const str = (source as StringLiteralType).value; + + // If the type contains `number` or a number literal and the string isn't a valid number, exclude numbers + if (allTypeFlags & TypeFlags.NumberLike && !isValidNumberString(str, /*roundTripOnly*/ true)) { + allTypeFlags &= ~TypeFlags.NumberLike; + } + + // If the type contains `bigint` or a bigint literal and the string isn't a valid bigint, exclude bigints + if (allTypeFlags & TypeFlags.BigIntLike && !isValidBigIntString(str, /*roundTripOnly*/ true)) { + allTypeFlags &= ~TypeFlags.BigIntLike; + } + + // for each type in the constraint, find the highest priority matching type + const matchingType = reduceLeft(constraintTypes, (left, right) => + !(right.flags & allTypeFlags) ? left : + left.flags & TypeFlags.String ? left : right.flags & TypeFlags.String ? source : + left.flags & TypeFlags.TemplateLiteral ? left : right.flags & TypeFlags.TemplateLiteral && isTypeMatchedByTemplateLiteralType(source, right as TemplateLiteralType) ? source : + left.flags & TypeFlags.StringMapping ? left : right.flags & TypeFlags.StringMapping && str === applyStringMapping(right.symbol, str) ? source : + left.flags & TypeFlags.StringLiteral ? left : right.flags & TypeFlags.StringLiteral && (right as StringLiteralType).value === str ? right : + left.flags & TypeFlags.Number ? left : right.flags & TypeFlags.Number ? getNumberLiteralType(+str) : + left.flags & TypeFlags.Enum ? left : right.flags & TypeFlags.Enum ? getNumberLiteralType(+str) : + left.flags & TypeFlags.NumberLiteral ? left : right.flags & TypeFlags.NumberLiteral && (right as NumberLiteralType).value === +str ? right : + left.flags & TypeFlags.BigInt ? left : right.flags & TypeFlags.BigInt ? parseBigIntLiteralType(str) : + left.flags & TypeFlags.BigIntLiteral ? left : right.flags & TypeFlags.BigIntLiteral && pseudoBigIntToString((right as BigIntLiteralType).value) === str ? right : + left.flags & TypeFlags.Boolean ? left : right.flags & TypeFlags.Boolean ? str === "true" ? trueType : str === "false" ? falseType : booleanType : + left.flags & TypeFlags.BooleanLiteral ? left : right.flags & TypeFlags.BooleanLiteral && (right as IntrinsicType).intrinsicName === str ? right : + left.flags & TypeFlags.Undefined ? left : right.flags & TypeFlags.Undefined && (right as IntrinsicType).intrinsicName === str ? right : + left.flags & TypeFlags.Null ? left : right.flags & TypeFlags.Null && (right as IntrinsicType).intrinsicName === str ? right : + left, neverType as Type); + + if (!(matchingType.flags & TypeFlags.Never)) { + inferFromTypes(matchingType, target); + continue; + } + } + } + } + + inferFromTypes(source, target); + } + } + } + + function inferFromGenericMappedTypes(source: MappedType, target: MappedType) { + // The source and target types are generic types { [P in S]: X } and { [P in T]: Y }, so we infer + // from S to T and from X to Y. + inferFromTypes(getConstraintTypeFromMappedType(source), getConstraintTypeFromMappedType(target)); + inferFromTypes(getTemplateTypeFromMappedType(source), getTemplateTypeFromMappedType(target)); + const sourceNameType = getNameTypeFromMappedType(source); + const targetNameType = getNameTypeFromMappedType(target); + if (sourceNameType && targetNameType) inferFromTypes(sourceNameType, targetNameType); + } + + function inferFromObjectTypes(source: Type, target: Type) { + if ( + getObjectFlags(source) & ObjectFlags.Reference && getObjectFlags(target) & ObjectFlags.Reference && ( + (source as TypeReference).target === (target as TypeReference).target || isArrayType(source) && isArrayType(target) + ) + ) { + // If source and target are references to the same generic type, infer from type arguments + inferFromTypeArguments(getTypeArguments(source as TypeReference), getTypeArguments(target as TypeReference), getVariances((source as TypeReference).target)); + return; + } + if (isGenericMappedType(source) && isGenericMappedType(target)) { + inferFromGenericMappedTypes(source, target); + } + if (getObjectFlags(target) & ObjectFlags.Mapped && !(target as MappedType).declaration.nameType) { + const constraintType = getConstraintTypeFromMappedType(target as MappedType); + if (inferToMappedType(source, target as MappedType, constraintType)) { + return; + } + } + // Infer from the members of source and target only if the two types are possibly related + if (!typesDefinitelyUnrelated(source, target)) { + if (isArrayOrTupleType(source)) { + if (isTupleType(target)) { + const sourceArity = getTypeReferenceArity(source); + const targetArity = getTypeReferenceArity(target); + const elementTypes = getTypeArguments(target); + const elementFlags = target.target.elementFlags; + // When source and target are tuple types with the same structure (fixed, variadic, and rest are matched + // to the same kind in each position), simply infer between the element types. + if (isTupleType(source) && isTupleTypeStructureMatching(source, target)) { + for (let i = 0; i < targetArity; i++) { + inferFromTypes(getTypeArguments(source)[i], elementTypes[i]); + } + return; + } + const startLength = isTupleType(source) ? Math.min(source.target.fixedLength, target.target.fixedLength) : 0; + const endLength = Math.min(isTupleType(source) ? getEndElementCount(source.target, ElementFlags.Fixed) : 0, target.target.combinedFlags & ElementFlags.Variable ? getEndElementCount(target.target, ElementFlags.Fixed) : 0); + // Infer between starting fixed elements. + for (let i = 0; i < startLength; i++) { + inferFromTypes(getTypeArguments(source)[i], elementTypes[i]); + } + if (!isTupleType(source) || sourceArity - startLength - endLength === 1 && source.target.elementFlags[startLength] & ElementFlags.Rest) { + // Single rest element remains in source, infer from that to every element in target + const restType = getTypeArguments(source)[startLength]; + for (let i = startLength; i < targetArity - endLength; i++) { + inferFromTypes(elementFlags[i] & ElementFlags.Variadic ? createArrayType(restType) : restType, elementTypes[i]); + } + } + else { + const middleLength = targetArity - startLength - endLength; + if (middleLength === 2) { + if (elementFlags[startLength] & elementFlags[startLength + 1] & ElementFlags.Variadic) { + // Middle of target is [...T, ...U] and source is tuple type + const targetInfo = getInferenceInfoForType(elementTypes[startLength]); + if (targetInfo && targetInfo.impliedArity !== undefined) { + // Infer slices from source based on implied arity of T. + inferFromTypes(sliceTupleType(source, startLength, endLength + sourceArity - targetInfo.impliedArity), elementTypes[startLength]); + inferFromTypes(sliceTupleType(source, startLength + targetInfo.impliedArity, endLength), elementTypes[startLength + 1]); + } + } + else if (elementFlags[startLength] & ElementFlags.Variadic && elementFlags[startLength + 1] & ElementFlags.Rest) { + // Middle of target is [...T, ...rest] and source is tuple type + // if T is constrained by a fixed-size tuple we might be able to use its arity to infer T + const param = getInferenceInfoForType(elementTypes[startLength])?.typeParameter; + const constraint = param && getBaseConstraintOfType(param); + if (constraint && isTupleType(constraint) && !(constraint.target.combinedFlags & ElementFlags.Variable)) { + const impliedArity = constraint.target.fixedLength; + inferFromTypes(sliceTupleType(source, startLength, sourceArity - (startLength + impliedArity)), elementTypes[startLength]); + inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength + impliedArity, endLength)!, elementTypes[startLength + 1]); + } + } + else if (elementFlags[startLength] & ElementFlags.Rest && elementFlags[startLength + 1] & ElementFlags.Variadic) { + // Middle of target is [...rest, ...T] and source is tuple type + // if T is constrained by a fixed-size tuple we might be able to use its arity to infer T + const param = getInferenceInfoForType(elementTypes[startLength + 1])?.typeParameter; + const constraint = param && getBaseConstraintOfType(param); + if (constraint && isTupleType(constraint) && !(constraint.target.combinedFlags & ElementFlags.Variable)) { + const impliedArity = constraint.target.fixedLength; + const endIndex = sourceArity - getEndElementCount(target.target, ElementFlags.Fixed); + const startIndex = endIndex - impliedArity; + const trailingSlice = createTupleType(getTypeArguments(source).slice(startIndex, endIndex), source.target.elementFlags.slice(startIndex, endIndex), /*readonly*/ false, source.target.labeledElementDeclarations && source.target.labeledElementDeclarations.slice(startIndex, endIndex)); + + inferFromTypes(getElementTypeOfSliceOfTupleType(source, startLength, endLength + impliedArity)!, elementTypes[startLength]); + inferFromTypes(trailingSlice, elementTypes[startLength + 1]); + } + } + } + else if (middleLength === 1 && elementFlags[startLength] & ElementFlags.Variadic) { + // Middle of target is exactly one variadic element. Infer the slice between the fixed parts in the source. + // If target ends in optional element(s), make a lower priority a speculative inference. + const endsInOptional = target.target.elementFlags[targetArity - 1] & ElementFlags.Optional; + const sourceSlice = sliceTupleType(source, startLength, endLength); + inferWithPriority(sourceSlice, elementTypes[startLength], endsInOptional ? InferencePriority.SpeculativeTuple : 0); + } + else if (middleLength === 1 && elementFlags[startLength] & ElementFlags.Rest) { + // Middle of target is exactly one rest element. If middle of source is not empty, infer union of middle element types. + const restType = getElementTypeOfSliceOfTupleType(source, startLength, endLength); + if (restType) { + inferFromTypes(restType, elementTypes[startLength]); + } + } + } + // Infer between ending fixed elements + for (let i = 0; i < endLength; i++) { + inferFromTypes(getTypeArguments(source)[sourceArity - i - 1], elementTypes[targetArity - i - 1]); + } + return; + } + if (isArrayType(target)) { + inferFromIndexTypes(source, target); + return; + } + } + inferFromProperties(source, target); + inferFromSignatures(source, target, SignatureKind.Call); + inferFromSignatures(source, target, SignatureKind.Construct); + inferFromIndexTypes(source, target); + } + } + + function inferFromProperties(source: Type, target: Type) { + const properties = getPropertiesOfObjectType(target); + for (const targetProp of properties) { + const sourceProp = getPropertyOfType(source, targetProp.escapedName); + if (sourceProp && !some(sourceProp.declarations, hasSkipDirectInferenceFlag)) { + inferFromTypes( + removeMissingType(getTypeOfSymbol(sourceProp), !!(sourceProp.flags & SymbolFlags.Optional)), + removeMissingType(getTypeOfSymbol(targetProp), !!(targetProp.flags & SymbolFlags.Optional)), + ); + } + } + } + + function inferFromSignatures(source: Type, target: Type, kind: SignatureKind) { + const sourceSignatures = getSignaturesOfType(source, kind); + const sourceLen = sourceSignatures.length; + if (sourceLen > 0) { + // We match source and target signatures from the bottom up, and if the source has fewer signatures + // than the target, we infer from the first source signature to the excess target signatures. + const targetSignatures = getSignaturesOfType(target, kind); + const targetLen = targetSignatures.length; + for (let i = 0; i < targetLen; i++) { + const sourceIndex = Math.max(sourceLen - targetLen + i, 0); + inferFromSignature(getBaseSignature(sourceSignatures[sourceIndex]), getErasedSignature(targetSignatures[i])); + } + } + } + + function inferFromSignature(source: Signature, target: Signature) { + if (!(source.flags & SignatureFlags.IsNonInferrable)) { + const saveBivariant = bivariant; + const kind = target.declaration ? target.declaration.kind : SyntaxKind.Unknown; + // Once we descend into a bivariant signature we remain bivariant for all nested inferences + bivariant = bivariant || kind === SyntaxKind.MethodDeclaration || kind === SyntaxKind.MethodSignature || kind === SyntaxKind.Constructor; + applyToParameterTypes(source, target, inferFromContravariantTypesIfStrictFunctionTypes); + bivariant = saveBivariant; + } + applyToReturnTypes(source, target, inferFromTypes); + } + + function inferFromIndexTypes(source: Type, target: Type) { + // Inferences across mapped type index signatures are pretty much the same a inferences to homomorphic variables + const priority = (getObjectFlags(source) & getObjectFlags(target) & ObjectFlags.Mapped) ? InferencePriority.HomomorphicMappedType : 0; + const indexInfos = getIndexInfosOfType(target); + if (isObjectTypeWithInferableIndex(source)) { + for (const targetInfo of indexInfos) { + const propTypes: Type[] = []; + for (const prop of getPropertiesOfType(source)) { + if (isApplicableIndexType(getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique), targetInfo.keyType)) { + const propType = getTypeOfSymbol(prop); + propTypes.push(prop.flags & SymbolFlags.Optional ? removeMissingOrUndefinedType(propType) : propType); + } + } + for (const info of getIndexInfosOfType(source)) { + if (isApplicableIndexType(info.keyType, targetInfo.keyType)) { + propTypes.push(info.type); + } + } + if (propTypes.length) { + inferWithPriority(getUnionType(propTypes), targetInfo.type, priority); + } + } + } + for (const targetInfo of indexInfos) { + const sourceInfo = getApplicableIndexInfo(source, targetInfo.keyType); + if (sourceInfo) { + inferWithPriority(sourceInfo.type, targetInfo.type, priority); + } + } + } + } + + function isTypeOrBaseIdenticalTo(s: Type, t: Type) { + return t === missingType ? s === t : + (isTypeIdenticalTo(s, t) || !!(t.flags & TypeFlags.String && s.flags & TypeFlags.StringLiteral || t.flags & TypeFlags.Number && s.flags & TypeFlags.NumberLiteral)); + } + + function isTypeCloselyMatchedBy(s: Type, t: Type) { + return !!(s.flags & TypeFlags.Object && t.flags & TypeFlags.Object && s.symbol && s.symbol === t.symbol || + s.aliasSymbol && s.aliasTypeArguments && s.aliasSymbol === t.aliasSymbol); + } + + function hasPrimitiveConstraint(type: TypeParameter): boolean { + const constraint = getConstraintOfTypeParameter(type); + return !!constraint && maybeTypeOfKind(constraint.flags & TypeFlags.Conditional ? getDefaultConstraintOfConditionalType(constraint as ConditionalType) : constraint, TypeFlags.Primitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping); + } + + function isObjectLiteralType(type: Type) { + return !!(getObjectFlags(type) & ObjectFlags.ObjectLiteral); + } + + function isObjectOrArrayLiteralType(type: Type) { + return !!(getObjectFlags(type) & (ObjectFlags.ObjectLiteral | ObjectFlags.ArrayLiteral)); + } + + function unionObjectAndArrayLiteralCandidates(candidates: Type[]): Type[] { + if (candidates.length > 1) { + const objectLiterals = filter(candidates, isObjectOrArrayLiteralType); + if (objectLiterals.length) { + const literalsType = getUnionType(objectLiterals, UnionReduction.Subtype); + return concatenate(filter(candidates, t => !isObjectOrArrayLiteralType(t)), [literalsType]); + } + } + return candidates; + } + + function getContravariantInference(inference: InferenceInfo) { + return inference.priority! & InferencePriority.PriorityImpliesCombination ? getIntersectionType(inference.contraCandidates!) : getCommonSubtype(inference.contraCandidates!); + } + + function getCovariantInference(inference: InferenceInfo, signature: Signature) { + // Extract all object and array literal types and replace them with a single widened and normalized type. + const candidates = unionObjectAndArrayLiteralCandidates(inference.candidates!); + // We widen inferred literal types if + // all inferences were made to top-level occurrences of the type parameter, and + // the type parameter has no constraint or its constraint includes no primitive or literal types, and + // the type parameter was fixed during inference or does not occur at top-level in the return type. + const primitiveConstraint = hasPrimitiveConstraint(inference.typeParameter) || isConstTypeVariable(inference.typeParameter); + const widenLiteralTypes = !primitiveConstraint && inference.topLevel && + (inference.isFixed || !isTypeParameterAtTopLevelInReturnType(signature, inference.typeParameter)); + const baseCandidates = primitiveConstraint ? sameMap(candidates, getRegularTypeOfLiteralType) : + widenLiteralTypes ? sameMap(candidates, getWidenedLiteralType) : + candidates; + // If all inferences were made from a position that implies a combined result, infer a union type. + // Otherwise, infer a common supertype. + const unwidenedType = inference.priority! & InferencePriority.PriorityImpliesCombination ? + getUnionType(baseCandidates, UnionReduction.Subtype) : + getCommonSupertype(baseCandidates); + return getWidenedType(unwidenedType); + } + + function getInferredType(context: InferenceContext, index: number): Type { + const inference = context.inferences[index]; + if (!inference.inferredType) { + let inferredType: Type | undefined; + let fallbackType: Type | undefined; + if (context.signature) { + const inferredCovariantType = inference.candidates ? getCovariantInference(inference, context.signature) : undefined; + const inferredContravariantType = inference.contraCandidates ? getContravariantInference(inference) : undefined; + if (inferredCovariantType || inferredContravariantType) { + // If we have both co- and contra-variant inferences, we prefer the co-variant inference if it is not 'never', + // all co-variant inferences are assignable to it (i.e. it isn't one of a conflicting set of candidates), it is + // assignable to some contra-variant inference, and no other type parameter is constrained to this type parameter + // and has inferences that would conflict. Otherwise, we prefer the contra-variant inference. + // Similarly ignore co-variant `any` inference when both are available as almost everything is assignable to it + // and it would spoil the overall inference. + const preferCovariantType = inferredCovariantType && (!inferredContravariantType || + !(inferredCovariantType.flags & (TypeFlags.Never | TypeFlags.Any)) && + some(inference.contraCandidates, t => isTypeAssignableTo(inferredCovariantType, t)) && + every(context.inferences, other => + other !== inference && getConstraintOfTypeParameter(other.typeParameter) !== inference.typeParameter || + every(other.candidates, t => isTypeAssignableTo(t, inferredCovariantType)))); + inferredType = preferCovariantType ? inferredCovariantType : inferredContravariantType; + fallbackType = preferCovariantType ? inferredContravariantType : inferredCovariantType; + } + else if (context.flags & InferenceFlags.NoDefault) { + // We use silentNeverType as the wildcard that signals no inferences. + inferredType = silentNeverType; + } + else { + // Infer either the default or the empty object type when no inferences were + // made. It is important to remember that in this case, inference still + // succeeds, meaning there is no error for not having inference candidates. An + // inference error only occurs when there are *conflicting* candidates, i.e. + // candidates with no common supertype. + const defaultType = getDefaultFromTypeParameter(inference.typeParameter); + if (defaultType) { + // Instantiate the default type. Any forward reference to a type + // parameter should be instantiated to the empty object type. + inferredType = instantiateType(defaultType, mergeTypeMappers(createBackreferenceMapper(context, index), context.nonFixingMapper)); + } + } + } + else { + inferredType = getTypeFromInference(inference); + } + + inference.inferredType = inferredType || getDefaultTypeArgumentType(!!(context.flags & InferenceFlags.AnyDefault)); + + const constraint = getConstraintOfTypeParameter(inference.typeParameter); + if (constraint) { + const instantiatedConstraint = instantiateType(constraint, context.nonFixingMapper); + if (!inferredType || !context.compareTypes(inferredType, getTypeWithThisArgument(instantiatedConstraint, inferredType))) { + // If the fallback type satisfies the constraint, we pick it. Otherwise, we pick the constraint. + inference.inferredType = fallbackType && context.compareTypes(fallbackType, getTypeWithThisArgument(instantiatedConstraint, fallbackType)) ? fallbackType : instantiatedConstraint; + } + } + } + + return inference.inferredType; + } + + function getDefaultTypeArgumentType(isInJavaScriptFile: boolean): Type { + return isInJavaScriptFile ? anyType : unknownType; + } + + function getInferredTypes(context: InferenceContext): Type[] { + const result: Type[] = []; + for (let i = 0; i < context.inferences.length; i++) { + result.push(getInferredType(context, i)); + } + return result; + } + + // EXPRESSION TYPE CHECKING + + function getCannotFindNameDiagnosticForName(node: Identifier): DiagnosticMessage { + switch (node.escapedText) { + case "document": + case "console": + return Diagnostics.Cannot_find_name_0_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_include_dom; + case "$": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_jQuery_Try_npm_i_save_dev_types_Slashjquery_and_then_add_jquery_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_jQuery_Try_npm_i_save_dev_types_Slashjquery; + case "describe": + case "suite": + case "it": + case "test": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_a_test_runner_Try_npm_i_save_dev_types_Slashjest_or_npm_i_save_dev_types_Slashmocha_and_then_add_jest_or_mocha_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_a_test_runner_Try_npm_i_save_dev_types_Slashjest_or_npm_i_save_dev_types_Slashmocha; + case "process": + case "require": + case "Buffer": + case "module": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_node_Try_npm_i_save_dev_types_Slashnode_and_then_add_node_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_node_Try_npm_i_save_dev_types_Slashnode; + case "Bun": + return compilerOptions.types + ? Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_Bun_Try_npm_i_save_dev_types_Slashbun_and_then_add_bun_to_the_types_field_in_your_tsconfig + : Diagnostics.Cannot_find_name_0_Do_you_need_to_install_type_definitions_for_Bun_Try_npm_i_save_dev_types_Slashbun; + case "Map": + case "Set": + case "Promise": + case "Symbol": + case "WeakMap": + case "WeakSet": + case "Iterator": + case "AsyncIterator": + case "SharedArrayBuffer": + case "Atomics": + case "AsyncIterable": + case "AsyncIterableIterator": + case "AsyncGenerator": + case "AsyncGeneratorFunction": + case "BigInt": + case "Reflect": + case "BigInt64Array": + case "BigUint64Array": + return Diagnostics.Cannot_find_name_0_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_1_or_later; + case "await": + if (isCallExpression(node.parent)) { + return Diagnostics.Cannot_find_name_0_Did_you_mean_to_write_this_in_an_async_function; + } + // falls through + default: + if (node.parent.kind === SyntaxKind.ShorthandPropertyAssignment) { + return Diagnostics.No_value_exists_in_scope_for_the_shorthand_property_0_Either_declare_one_or_provide_an_initializer; + } + else { + return Diagnostics.Cannot_find_name_0; + } + } + } + + function getResolvedSymbol(node: Identifier): Symbol { + const links = getNodeLinks(node); + if (!links.resolvedSymbol) { + links.resolvedSymbol = !nodeIsMissing(node) && + resolveName( + node, + node, + SymbolFlags.Value | SymbolFlags.ExportValue, + getCannotFindNameDiagnosticForName(node), + !isWriteOnlyAccess(node), + /*excludeGlobals*/ false, + ) || unknownSymbol; + } + return links.resolvedSymbol; + } + + function isInAmbientOrTypeNode(node: Node): boolean { + return !!(node.flags & NodeFlags.Ambient || findAncestor(node, n => isInterfaceDeclaration(n) || isTypeAliasDeclaration(n) || isTypeLiteralNode(n))); + } + + // Return the flow cache key for a "dotted name" (i.e. a sequence of identifiers + // separated by dots). The key consists of the id of the symbol referenced by the + // leftmost identifier followed by zero or more property names separated by dots. + // The result is undefined if the reference isn't a dotted name. + function getFlowCacheKey(node: Node, declaredType: Type, initialType: Type, flowContainer: Node | undefined): string | undefined { + switch (node.kind) { + case SyntaxKind.Identifier: + if (!isThisInTypeQuery(node)) { + const symbol = getResolvedSymbol(node as Identifier); + return symbol !== unknownSymbol ? `${flowContainer ? getNodeId(flowContainer) : "-1"}|${getTypeId(declaredType)}|${getTypeId(initialType)}|${getSymbolId(symbol)}` : undefined; + } + // falls through + case SyntaxKind.ThisKeyword: + return `0|${flowContainer ? getNodeId(flowContainer) : "-1"}|${getTypeId(declaredType)}|${getTypeId(initialType)}`; + case SyntaxKind.NonNullExpression: + case SyntaxKind.ParenthesizedExpression: + return getFlowCacheKey((node as NonNullExpression | ParenthesizedExpression).expression, declaredType, initialType, flowContainer); + case SyntaxKind.QualifiedName: + const left = getFlowCacheKey((node as QualifiedName).left, declaredType, initialType, flowContainer); + return left && `${left}.${(node as QualifiedName).right.escapedText}`; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + const propName = getAccessedPropertyName(node as AccessExpression); + if (propName !== undefined) { + const key = getFlowCacheKey((node as AccessExpression).expression, declaredType, initialType, flowContainer); + return key && `${key}.${propName}`; + } + if (isElementAccessExpression(node) && isIdentifier(node.argumentExpression)) { + const symbol = getResolvedSymbol(node.argumentExpression); + if (isConstantVariable(symbol) || isParameterOrMutableLocalVariable(symbol) && !isSymbolAssigned(symbol)) { + const key = getFlowCacheKey((node as AccessExpression).expression, declaredType, initialType, flowContainer); + return key && `${key}.@${getSymbolId(symbol)}`; + } + } + break; + case SyntaxKind.ObjectBindingPattern: + case SyntaxKind.ArrayBindingPattern: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + // Handle pseudo-references originating in getNarrowedTypeOfSymbol. + return `${getNodeId(node)}#${getTypeId(declaredType)}`; + } + return undefined; + } + + function isMatchingReference(source: Node, target: Node): boolean { + switch (target.kind) { + case SyntaxKind.ParenthesizedExpression: + case SyntaxKind.NonNullExpression: + return isMatchingReference(source, (target as NonNullExpression | ParenthesizedExpression).expression); + case SyntaxKind.BinaryExpression: + return (isAssignmentExpression(target) && isMatchingReference(source, target.left)) || + (isBinaryExpression(target) && target.operatorToken.kind === SyntaxKind.CommaToken && isMatchingReference(source, target.right)); + } + switch (source.kind) { + case SyntaxKind.MetaProperty: + return target.kind === SyntaxKind.MetaProperty + && (source as MetaProperty).keywordToken === (target as MetaProperty).keywordToken + && (source as MetaProperty).name.escapedText === (target as MetaProperty).name.escapedText; + case SyntaxKind.Identifier: + case SyntaxKind.PrivateIdentifier: + return isThisInTypeQuery(source) ? + target.kind === SyntaxKind.ThisKeyword : + target.kind === SyntaxKind.Identifier && getResolvedSymbol(source as Identifier) === getResolvedSymbol(target as Identifier) || + (isVariableDeclaration(target) || isBindingElement(target)) && + getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(source as Identifier)) === getSymbolOfDeclaration(target); + case SyntaxKind.ThisKeyword: + return target.kind === SyntaxKind.ThisKeyword; + case SyntaxKind.SuperKeyword: + return target.kind === SyntaxKind.SuperKeyword; + case SyntaxKind.NonNullExpression: + case SyntaxKind.ParenthesizedExpression: + return isMatchingReference((source as NonNullExpression | ParenthesizedExpression).expression, target); + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + const sourcePropertyName = getAccessedPropertyName(source as AccessExpression); + if (sourcePropertyName !== undefined) { + const targetPropertyName = isAccessExpression(target) ? getAccessedPropertyName(target) : undefined; + if (targetPropertyName !== undefined) { + return targetPropertyName === sourcePropertyName && isMatchingReference((source as AccessExpression).expression, (target as AccessExpression).expression); + } + } + if (isElementAccessExpression(source) && isElementAccessExpression(target) && isIdentifier(source.argumentExpression) && isIdentifier(target.argumentExpression)) { + const symbol = getResolvedSymbol(source.argumentExpression); + if (symbol === getResolvedSymbol(target.argumentExpression) && (isConstantVariable(symbol) || isParameterOrMutableLocalVariable(symbol) && !isSymbolAssigned(symbol))) { + return isMatchingReference(source.expression, target.expression); + } + } + break; + case SyntaxKind.QualifiedName: + return isAccessExpression(target) && + (source as QualifiedName).right.escapedText === getAccessedPropertyName(target) && + isMatchingReference((source as QualifiedName).left, target.expression); + case SyntaxKind.BinaryExpression: + return (isBinaryExpression(source) && source.operatorToken.kind === SyntaxKind.CommaToken && isMatchingReference(source.right, target)); + } + return false; + } + + function getAccessedPropertyName(access: AccessExpression | BindingElement | ParameterDeclaration): __String | undefined { + if (isPropertyAccessExpression(access)) { + return access.name.escapedText; + } + if (isElementAccessExpression(access)) { + return tryGetElementAccessExpressionName(access); + } + if (isBindingElement(access)) { + const name = getDestructuringPropertyName(access); + return name ? escapeLeadingUnderscores(name) : undefined; + } + if (isParameter(access)) { + return ("" + access.parent.parameters.indexOf(access)) as __String; + } + return undefined; + } + + function tryGetNameFromType(type: Type) { + return type.flags & TypeFlags.UniqueESSymbol ? (type as UniqueESSymbolType).escapedName : + type.flags & TypeFlags.StringOrNumberLiteral ? escapeLeadingUnderscores("" + (type as StringLiteralType | NumberLiteralType).value) : undefined; + } + + function tryGetElementAccessExpressionName(node: ElementAccessExpression) { + return isStringOrNumericLiteralLike(node.argumentExpression) ? escapeLeadingUnderscores(node.argumentExpression.text) : + isEntityNameExpression(node.argumentExpression) ? tryGetNameFromEntityNameExpression(node.argumentExpression) : undefined; + } + + function tryGetNameFromEntityNameExpression(node: EntityNameOrEntityNameExpression) { + const symbol = resolveEntityName(node, SymbolFlags.Value, /*ignoreErrors*/ true); + if (!symbol || !(isConstantVariable(symbol) || (symbol.flags & SymbolFlags.EnumMember))) return undefined; + + const declaration = symbol.valueDeclaration; + if (declaration === undefined) return undefined; + + const type = tryGetTypeFromEffectiveTypeNode(declaration); + if (type) { + const name = tryGetNameFromType(type); + if (name !== undefined) { + return name; + } + } + if (hasOnlyExpressionInitializer(declaration) && isBlockScopedNameDeclaredBeforeUse(declaration, node)) { + const initializer = getEffectiveInitializer(declaration); + if (initializer) { + const initializerType = isBindingPattern(declaration.parent) ? getTypeForBindingElement(declaration as BindingElement) : getTypeOfExpression(initializer); + return initializerType && tryGetNameFromType(initializerType); + } + if (isEnumMember(declaration)) { + return getTextOfPropertyName(declaration.name); + } + } + return undefined; + } + + function containsMatchingReference(source: Node, target: Node) { + while (isAccessExpression(source)) { + source = source.expression; + if (isMatchingReference(source, target)) { + return true; + } + } + return false; + } + + function optionalChainContainsReference(source: Node, target: Node) { + while (isOptionalChain(source)) { + source = source.expression; + if (isMatchingReference(source, target)) { + return true; + } + } + return false; + } + + function isDiscriminantProperty(type: Type | undefined, name: __String) { + if (type && type.flags & TypeFlags.Union) { + const prop = getUnionOrIntersectionProperty(type as UnionType, name); + if (prop && getCheckFlags(prop) & CheckFlags.SyntheticProperty) { + // NOTE: cast to TransientSymbol should be safe because only TransientSymbols can have CheckFlags.SyntheticProperty + if ((prop as TransientSymbol).links.isDiscriminantProperty === undefined) { + (prop as TransientSymbol).links.isDiscriminantProperty = ((prop as TransientSymbol).links.checkFlags & CheckFlags.Discriminant) === CheckFlags.Discriminant && + !isGenericType(getTypeOfSymbol(prop)); + } + return !!(prop as TransientSymbol).links.isDiscriminantProperty; + } + } + return false; + } + + function findDiscriminantProperties(sourceProperties: Symbol[], target: Type): Symbol[] | undefined { + let result: Symbol[] | undefined; + for (const sourceProperty of sourceProperties) { + if (isDiscriminantProperty(target, sourceProperty.escapedName)) { + if (result) { + result.push(sourceProperty); + continue; + } + result = [sourceProperty]; + } + } + return result; + } + + // Given a set of constituent types and a property name, create and return a map keyed by the literal + // types of the property by that name in each constituent type. No map is returned if some key property + // has a non-literal type or if less than 10 or less than 50% of the constituents have a unique key. + // Entries with duplicate keys have unknownType as the value. + function mapTypesByKeyProperty(types: Type[], name: __String) { + const map = new Map(); + let count = 0; + for (const type of types) { + if (type.flags & (TypeFlags.Object | TypeFlags.Intersection | TypeFlags.InstantiableNonPrimitive)) { + const discriminant = getTypeOfPropertyOfType(type, name); + if (discriminant) { + if (!isLiteralType(discriminant)) { + return undefined; + } + let duplicate = false; + forEachType(discriminant, t => { + const id = getTypeId(getRegularTypeOfLiteralType(t)); + const existing = map.get(id); + if (!existing) { + map.set(id, type); + } + else if (existing !== unknownType) { + map.set(id, unknownType); + duplicate = true; + } + }); + if (!duplicate) count++; + } + } + } + return count >= 10 && count * 2 >= types.length ? map : undefined; + } + + // Return the name of a discriminant property for which it was possible and feasible to construct a map of + // constituent types keyed by the literal types of the property by that name in each constituent type. + function getKeyPropertyName(unionType: UnionType): __String | undefined { + const types = unionType.types; + // We only construct maps for unions with many non-primitive constituents. + if ( + types.length < 10 || getObjectFlags(unionType) & ObjectFlags.PrimitiveUnion || + countWhere(types, t => !!(t.flags & (TypeFlags.Object | TypeFlags.InstantiableNonPrimitive))) < 10 + ) { + return undefined; + } + if (unionType.keyPropertyName === undefined) { + // The candidate key property name is the name of the first property with a unit type in one of the + // constituent types. + const keyPropertyName = forEach(types, t => + t.flags & (TypeFlags.Object | TypeFlags.InstantiableNonPrimitive) ? + forEach(getPropertiesOfType(t), p => isUnitType(getTypeOfSymbol(p)) ? p.escapedName : undefined) : + undefined); + const mapByKeyProperty = keyPropertyName && mapTypesByKeyProperty(types, keyPropertyName); + unionType.keyPropertyName = mapByKeyProperty ? keyPropertyName : "" as __String; + unionType.constituentMap = mapByKeyProperty; + } + return (unionType.keyPropertyName as string).length ? unionType.keyPropertyName : undefined; + } + + // Given a union type for which getKeyPropertyName returned a non-undefined result, return the constituent + // that corresponds to the given key type for that property name. + function getConstituentTypeForKeyType(unionType: UnionType, keyType: Type) { + const result = unionType.constituentMap?.get(getTypeId(getRegularTypeOfLiteralType(keyType))); + return result !== unknownType ? result : undefined; + } + + function getMatchingUnionConstituentForType(unionType: UnionType, type: Type) { + const keyPropertyName = getKeyPropertyName(unionType); + const propType = keyPropertyName && getTypeOfPropertyOfType(type, keyPropertyName); + return propType && getConstituentTypeForKeyType(unionType, propType); + } + + function getMatchingUnionConstituentForObjectLiteral(unionType: UnionType, node: ObjectLiteralExpression) { + const keyPropertyName = getKeyPropertyName(unionType); + const propNode = keyPropertyName && find(node.properties, p => + p.symbol && p.kind === SyntaxKind.PropertyAssignment && + p.symbol.escapedName === keyPropertyName && isPossiblyDiscriminantValue(p.initializer)); + const propType = propNode && getContextFreeTypeOfExpression((propNode as PropertyAssignment).initializer); + return propType && getConstituentTypeForKeyType(unionType, propType); + } + + function isOrContainsMatchingReference(source: Node, target: Node) { + return isMatchingReference(source, target) || containsMatchingReference(source, target); + } + + function hasMatchingArgument(expression: CallExpression | NewExpression, reference: Node) { + if (expression.arguments) { + for (const argument of expression.arguments) { + if (isOrContainsMatchingReference(reference, argument) || optionalChainContainsReference(argument, reference)) { + return true; + } + } + } + if ( + expression.expression.kind === SyntaxKind.PropertyAccessExpression && + isOrContainsMatchingReference(reference, (expression.expression as PropertyAccessExpression).expression) + ) { + return true; + } + return false; + } + + function getFlowNodeId(flow: FlowNode): number { + if (flow.id <= 0) { + flow.id = nextFlowId; + nextFlowId++; + } + return flow.id; + } + + function typeMaybeAssignableTo(source: Type, target: Type) { + if (!(source.flags & TypeFlags.Union)) { + return isTypeAssignableTo(source, target); + } + for (const t of (source as UnionType).types) { + if (isTypeAssignableTo(t, target)) { + return true; + } + } + return false; + } + + // Remove those constituent types of declaredType to which no constituent type of assignedType is assignable. + // For example, when a variable of type number | string | boolean is assigned a value of type number | boolean, + // we remove type string. + function getAssignmentReducedType(declaredType: UnionType, assignedType: Type) { + if (declaredType === assignedType) { + return declaredType; + } + if (assignedType.flags & TypeFlags.Never) { + return assignedType; + } + const key = `A${getTypeId(declaredType)},${getTypeId(assignedType)}`; + return getCachedType(key) ?? setCachedType(key, getAssignmentReducedTypeWorker(declaredType, assignedType)); + } + + function getAssignmentReducedTypeWorker(declaredType: UnionType, assignedType: Type) { + const filteredType = filterType(declaredType, t => typeMaybeAssignableTo(assignedType, t)); + // Ensure that we narrow to fresh types if the assignment is a fresh boolean literal type. + const reducedType = assignedType.flags & TypeFlags.BooleanLiteral && isFreshLiteralType(assignedType) ? mapType(filteredType, getFreshTypeOfLiteralType) : filteredType; + // Our crude heuristic produces an invalid result in some cases: see GH#26130. + // For now, when that happens, we give up and don't narrow at all. (This also + // means we'll never narrow for erroneous assignments where the assigned type + // is not assignable to the declared type.) + return isTypeAssignableTo(assignedType, reducedType) ? reducedType : declaredType; + } + + function isFunctionObjectType(type: ObjectType): boolean { + // We do a quick check for a "bind" property before performing the more expensive subtype + // check. This gives us a quicker out in the common case where an object type is not a function. + const resolved = resolveStructuredTypeMembers(type); + return !!(resolved.callSignatures.length || resolved.constructSignatures.length || + resolved.members.get("bind" as __String) && isTypeSubtypeOf(type, globalFunctionType)); + } + + function getTypeFacts(type: Type, mask: TypeFacts): TypeFacts { + return getTypeFactsWorker(type, mask) & mask; + } + + function hasTypeFacts(type: Type, mask: TypeFacts): boolean { + return getTypeFacts(type, mask) !== 0; + } + + function getTypeFactsWorker(type: Type, callerOnlyNeeds: TypeFacts): TypeFacts { + if (type.flags & (TypeFlags.Intersection | TypeFlags.Instantiable)) { + type = getBaseConstraintOfType(type) || unknownType; + } + const flags = type.flags; + if (flags & (TypeFlags.String | TypeFlags.StringMapping)) { + return strictNullChecks ? TypeFacts.StringStrictFacts : TypeFacts.StringFacts; + } + if (flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral)) { + const isEmpty = flags & TypeFlags.StringLiteral && (type as StringLiteralType).value === ""; + return strictNullChecks ? + isEmpty ? TypeFacts.EmptyStringStrictFacts : TypeFacts.NonEmptyStringStrictFacts : + isEmpty ? TypeFacts.EmptyStringFacts : TypeFacts.NonEmptyStringFacts; + } + if (flags & (TypeFlags.Number | TypeFlags.Enum)) { + return strictNullChecks ? TypeFacts.NumberStrictFacts : TypeFacts.NumberFacts; + } + if (flags & TypeFlags.NumberLiteral) { + const isZero = (type as NumberLiteralType).value === 0; + return strictNullChecks ? + isZero ? TypeFacts.ZeroNumberStrictFacts : TypeFacts.NonZeroNumberStrictFacts : + isZero ? TypeFacts.ZeroNumberFacts : TypeFacts.NonZeroNumberFacts; + } + if (flags & TypeFlags.BigInt) { + return strictNullChecks ? TypeFacts.BigIntStrictFacts : TypeFacts.BigIntFacts; + } + if (flags & TypeFlags.BigIntLiteral) { + const isZero = isZeroBigInt(type as BigIntLiteralType); + return strictNullChecks ? + isZero ? TypeFacts.ZeroBigIntStrictFacts : TypeFacts.NonZeroBigIntStrictFacts : + isZero ? TypeFacts.ZeroBigIntFacts : TypeFacts.NonZeroBigIntFacts; + } + if (flags & TypeFlags.Boolean) { + return strictNullChecks ? TypeFacts.BooleanStrictFacts : TypeFacts.BooleanFacts; + } + if (flags & TypeFlags.BooleanLike) { + return strictNullChecks ? + (type === falseType || type === regularFalseType) ? TypeFacts.FalseStrictFacts : TypeFacts.TrueStrictFacts : + (type === falseType || type === regularFalseType) ? TypeFacts.FalseFacts : TypeFacts.TrueFacts; + } + if (flags & TypeFlags.Object) { + const possibleFacts = strictNullChecks + ? TypeFacts.EmptyObjectStrictFacts | TypeFacts.FunctionStrictFacts | TypeFacts.ObjectStrictFacts + : TypeFacts.EmptyObjectFacts | TypeFacts.FunctionFacts | TypeFacts.ObjectFacts; + + if ((callerOnlyNeeds & possibleFacts) === 0) { + // If the caller doesn't care about any of the facts that we could possibly produce, + // return zero so we can skip resolving members. + return 0; + } + + return getObjectFlags(type) & ObjectFlags.Anonymous && isEmptyObjectType(type as ObjectType) ? + strictNullChecks ? TypeFacts.EmptyObjectStrictFacts : TypeFacts.EmptyObjectFacts : + isFunctionObjectType(type as ObjectType) ? + strictNullChecks ? TypeFacts.FunctionStrictFacts : TypeFacts.FunctionFacts : + strictNullChecks ? TypeFacts.ObjectStrictFacts : TypeFacts.ObjectFacts; + } + if (flags & TypeFlags.Void) { + return TypeFacts.VoidFacts; + } + if (flags & TypeFlags.Undefined) { + return TypeFacts.UndefinedFacts; + } + if (flags & TypeFlags.Null) { + return TypeFacts.NullFacts; + } + if (flags & TypeFlags.ESSymbolLike) { + return strictNullChecks ? TypeFacts.SymbolStrictFacts : TypeFacts.SymbolFacts; + } + if (flags & TypeFlags.NonPrimitive) { + return strictNullChecks ? TypeFacts.ObjectStrictFacts : TypeFacts.ObjectFacts; + } + if (flags & TypeFlags.Never) { + return TypeFacts.None; + } + if (flags & TypeFlags.Union) { + return reduceLeft((type as UnionType).types, (facts, t) => facts | getTypeFactsWorker(t, callerOnlyNeeds), TypeFacts.None); + } + if (flags & TypeFlags.Intersection) { + return getIntersectionTypeFacts(type as IntersectionType, callerOnlyNeeds); + } + return TypeFacts.UnknownFacts; + } + + function getIntersectionTypeFacts(type: IntersectionType, callerOnlyNeeds: TypeFacts): TypeFacts { + // When an intersection contains a primitive type we ignore object type constituents as they are + // presumably type tags. For example, in string & { __kind__: "name" } we ignore the object type. + const ignoreObjects = maybeTypeOfKind(type, TypeFlags.Primitive); + // When computing the type facts of an intersection type, certain type facts are computed as `and` + // and others are computed as `or`. + let oredFacts = TypeFacts.None; + let andedFacts = TypeFacts.All; + for (const t of type.types) { + if (!(ignoreObjects && t.flags & TypeFlags.Object)) { + const f = getTypeFactsWorker(t, callerOnlyNeeds); + oredFacts |= f; + andedFacts &= f; + } + } + return oredFacts & TypeFacts.OrFactsMask | andedFacts & TypeFacts.AndFactsMask; + } + + function getTypeWithFacts(type: Type, include: TypeFacts) { + return filterType(type, t => hasTypeFacts(t, include)); + } + + // This function is similar to getTypeWithFacts, except that in strictNullChecks mode it replaces type + // unknown with the union {} | null | undefined (and reduces that accordingly), and it intersects remaining + // instantiable types with {}, {} | null, or {} | undefined in order to remove null and/or undefined. + function getAdjustedTypeWithFacts(type: Type, facts: TypeFacts) { + const reduced = recombineUnknownType(getTypeWithFacts(strictNullChecks && type.flags & TypeFlags.Unknown ? unknownUnionType : type, facts)); + if (strictNullChecks) { + switch (facts) { + case TypeFacts.NEUndefined: + return removeNullableByIntersection(reduced, TypeFacts.EQUndefined, TypeFacts.EQNull, TypeFacts.IsNull, nullType); + case TypeFacts.NENull: + return removeNullableByIntersection(reduced, TypeFacts.EQNull, TypeFacts.EQUndefined, TypeFacts.IsUndefined, undefinedType); + case TypeFacts.NEUndefinedOrNull: + case TypeFacts.Truthy: + return mapType(reduced, t => hasTypeFacts(t, TypeFacts.EQUndefinedOrNull) ? getGlobalNonNullableTypeInstantiation(t) : t); + } + } + return reduced; + } + + function removeNullableByIntersection(type: Type, targetFacts: TypeFacts, otherFacts: TypeFacts, otherIncludesFacts: TypeFacts, otherType: Type) { + const facts = getTypeFacts(type, TypeFacts.EQUndefined | TypeFacts.EQNull | TypeFacts.IsUndefined | TypeFacts.IsNull); + // Simply return the type if it never compares equal to the target nullable. + if (!(facts & targetFacts)) { + return type; + } + // By default we intersect with a union of {} and the opposite nullable. + const emptyAndOtherUnion = getUnionType([emptyObjectType, otherType]); + // For each constituent type that can compare equal to the target nullable, intersect with the above union + // if the type doesn't already include the opppsite nullable and the constituent can compare equal to the + // opposite nullable; otherwise, just intersect with {}. + return mapType(type, t => hasTypeFacts(t, targetFacts) ? getIntersectionType([t, !(facts & otherIncludesFacts) && hasTypeFacts(t, otherFacts) ? emptyAndOtherUnion : emptyObjectType]) : t); + } + + function recombineUnknownType(type: Type) { + return type === unknownUnionType ? unknownType : type; + } + + function getTypeWithDefault(type: Type, defaultExpression: Expression) { + return defaultExpression ? + getUnionType([getNonUndefinedType(type), getTypeOfExpression(defaultExpression)]) : + type; + } + + function getTypeOfDestructuredProperty(type: Type, name: PropertyName) { + const nameType = getLiteralTypeFromPropertyName(name); + if (!isTypeUsableAsPropertyName(nameType)) return errorType; + const text = getPropertyNameFromType(nameType); + return getTypeOfPropertyOfType(type, text) || includeUndefinedInIndexSignature(getApplicableIndexInfoForName(type, text)?.type) || errorType; + } + + function getTypeOfDestructuredArrayElement(type: Type, index: number) { + return everyType(type, isTupleLikeType) && getTupleElementType(type, index) || + includeUndefinedInIndexSignature(checkIteratedTypeOrElementType(IterationUse.Destructuring, type, undefinedType, /*errorNode*/ undefined)) || + errorType; + } + + function includeUndefinedInIndexSignature(type: Type | undefined): Type | undefined { + if (!type) return type; + return compilerOptions.noUncheckedIndexedAccess ? + getUnionType([type, missingType]) : + type; + } + + function getTypeOfDestructuredSpreadExpression(type: Type) { + return createArrayType(checkIteratedTypeOrElementType(IterationUse.Destructuring, type, undefinedType, /*errorNode*/ undefined) || errorType); + } + + function getAssignedTypeOfBinaryExpression(node: BinaryExpression): Type { + const isDestructuringDefaultAssignment = node.parent.kind === SyntaxKind.ArrayLiteralExpression && isDestructuringAssignmentTarget(node.parent) || + node.parent.kind === SyntaxKind.PropertyAssignment && isDestructuringAssignmentTarget(node.parent.parent); + return isDestructuringDefaultAssignment ? + getTypeWithDefault(getAssignedType(node), node.right) : + getTypeOfExpression(node.right); + } + + function isDestructuringAssignmentTarget(parent: Node) { + return parent.parent.kind === SyntaxKind.BinaryExpression && (parent.parent as BinaryExpression).left === parent || + parent.parent.kind === SyntaxKind.ForOfStatement && (parent.parent as ForOfStatement).initializer === parent; + } + + function getAssignedTypeOfArrayLiteralElement(node: ArrayLiteralExpression, element: Expression): Type { + return getTypeOfDestructuredArrayElement(getAssignedType(node), node.elements.indexOf(element)); + } + + function getAssignedTypeOfSpreadExpression(node: SpreadElement): Type { + return getTypeOfDestructuredSpreadExpression(getAssignedType(node.parent as ArrayLiteralExpression)); + } + + function getAssignedTypeOfPropertyAssignment(node: PropertyAssignment | ShorthandPropertyAssignment): Type { + return getTypeOfDestructuredProperty(getAssignedType(node.parent), node.name); + } + + function getAssignedTypeOfShorthandPropertyAssignment(node: ShorthandPropertyAssignment): Type { + return getTypeWithDefault(getAssignedTypeOfPropertyAssignment(node), node.objectAssignmentInitializer!); + } + + function getAssignedType(node: Expression): Type { + const { parent } = node; + switch (parent.kind) { + case SyntaxKind.ForInStatement: + return stringType; + case SyntaxKind.ForOfStatement: + return checkRightHandSideOfForOf(parent as ForOfStatement) || errorType; + case SyntaxKind.BinaryExpression: + return getAssignedTypeOfBinaryExpression(parent as BinaryExpression); + case SyntaxKind.DeleteExpression: + return undefinedType; + case SyntaxKind.ArrayLiteralExpression: + return getAssignedTypeOfArrayLiteralElement(parent as ArrayLiteralExpression, node); + case SyntaxKind.SpreadElement: + return getAssignedTypeOfSpreadExpression(parent as SpreadElement); + case SyntaxKind.PropertyAssignment: + return getAssignedTypeOfPropertyAssignment(parent as PropertyAssignment); + case SyntaxKind.ShorthandPropertyAssignment: + return getAssignedTypeOfShorthandPropertyAssignment(parent as ShorthandPropertyAssignment); + } + return errorType; + } + + function getInitialTypeOfBindingElement(node: BindingElement): Type { + const pattern = node.parent; + const parentType = getInitialType(pattern.parent as VariableDeclaration | BindingElement); + const type = pattern.kind === SyntaxKind.ObjectBindingPattern ? + getTypeOfDestructuredProperty(parentType, node.propertyName || node.name as Identifier) : + !node.dotDotDotToken ? + getTypeOfDestructuredArrayElement(parentType, pattern.elements.indexOf(node)) : + getTypeOfDestructuredSpreadExpression(parentType); + return getTypeWithDefault(type, node.initializer!); + } + + function getTypeOfInitializer(node: Expression) { + // Return the cached type if one is available. If the type of the variable was inferred + // from its initializer, we'll already have cached the type. Otherwise we compute it now + // without caching such that transient types are reflected. + const links = getNodeLinks(node); + return links.resolvedType || getTypeOfExpression(node); + } + + function getInitialTypeOfVariableDeclaration(node: VariableDeclaration) { + if (node.initializer) { + return getTypeOfInitializer(node.initializer); + } + if (node.parent.parent.kind === SyntaxKind.ForInStatement) { + return stringType; + } + if (node.parent.parent.kind === SyntaxKind.ForOfStatement) { + return checkRightHandSideOfForOf(node.parent.parent) || errorType; + } + return errorType; + } + + function getInitialType(node: VariableDeclaration | BindingElement) { + return node.kind === SyntaxKind.VariableDeclaration ? + getInitialTypeOfVariableDeclaration(node) : + getInitialTypeOfBindingElement(node); + } + + function isEmptyArrayAssignment(node: VariableDeclaration | BindingElement | Expression) { + return node.kind === SyntaxKind.VariableDeclaration && (node as VariableDeclaration).initializer && + isEmptyArrayLiteral((node as VariableDeclaration).initializer!) || + node.kind !== SyntaxKind.BindingElement && node.parent.kind === SyntaxKind.BinaryExpression && + isEmptyArrayLiteral((node.parent as BinaryExpression).right); + } + + function getReferenceCandidate(node: Expression): Expression { + switch (node.kind) { + case SyntaxKind.ParenthesizedExpression: + return getReferenceCandidate((node as ParenthesizedExpression).expression); + case SyntaxKind.BinaryExpression: + switch ((node as BinaryExpression).operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.BarBarEqualsToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: + case SyntaxKind.QuestionQuestionEqualsToken: + return getReferenceCandidate((node as BinaryExpression).left); + case SyntaxKind.CommaToken: + return getReferenceCandidate((node as BinaryExpression).right); + } + } + return node; + } + + function getReferenceRoot(node: Node): Node { + const { parent } = node; + return parent.kind === SyntaxKind.ParenthesizedExpression || + parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken && (parent as BinaryExpression).left === node || + parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.CommaToken && (parent as BinaryExpression).right === node ? + getReferenceRoot(parent) : node; + } + + function getTypeOfSwitchClause(clause: CaseClause | DefaultClause) { + if (clause.kind === SyntaxKind.CaseClause) { + return getRegularTypeOfLiteralType(getTypeOfExpression(clause.expression)); + } + return neverType; + } + + function getSwitchClauseTypes(switchStatement: SwitchStatement): Type[] { + const links = getNodeLinks(switchStatement); + if (!links.switchTypes) { + links.switchTypes = []; + for (const clause of switchStatement.caseBlock.clauses) { + links.switchTypes.push(getTypeOfSwitchClause(clause)); + } + } + return links.switchTypes; + } + + // Get the type names from all cases in a switch on `typeof`. The default clause and/or duplicate type names are + // represented as undefined. Return undefined if one or more case clause expressions are not string literals. + function getSwitchClauseTypeOfWitnesses(switchStatement: SwitchStatement): (string | undefined)[] | undefined { + if (some(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.CaseClause && !isStringLiteralLike(clause.expression))) { + return undefined; + } + const witnesses: (string | undefined)[] = []; + for (const clause of switchStatement.caseBlock.clauses) { + const text = clause.kind === SyntaxKind.CaseClause ? (clause.expression as StringLiteralLike).text : undefined; + witnesses.push(text && !contains(witnesses, text) ? text : undefined); + } + return witnesses; + } + + function eachTypeContainedIn(source: Type, types: Type[]) { + return source.flags & TypeFlags.Union ? !forEach((source as UnionType).types, t => !contains(types, t)) : contains(types, source); + } + + function isTypeSubsetOf(source: Type, target: Type) { + return !!(source === target || source.flags & TypeFlags.Never || target.flags & TypeFlags.Union && isTypeSubsetOfUnion(source, target as UnionType)); + } + + function isTypeSubsetOfUnion(source: Type, target: UnionType) { + if (source.flags & TypeFlags.Union) { + for (const t of (source as UnionType).types) { + if (!containsType(target.types, t)) { + return false; + } + } + return true; + } + if (source.flags & TypeFlags.EnumLike && getBaseTypeOfEnumLikeType(source as LiteralType) === target) { + return true; + } + return containsType(target.types, source); + } + + function forEachType(type: Type, f: (t: Type) => T | undefined): T | undefined { + return type.flags & TypeFlags.Union ? forEach((type as UnionType).types, f) : f(type); + } + + function someType(type: Type, f: (t: Type) => boolean): boolean { + return type.flags & TypeFlags.Union ? some((type as UnionType).types, f) : f(type); + } + + function everyType(type: Type, f: (t: Type) => boolean): boolean { + return type.flags & TypeFlags.Union ? every((type as UnionType).types, f) : f(type); + } + + function everyContainedType(type: Type, f: (t: Type) => boolean): boolean { + return type.flags & TypeFlags.UnionOrIntersection ? every((type as UnionOrIntersectionType).types, f) : f(type); + } + + function filterType(type: Type, f: (t: Type) => boolean): Type { + if (type.flags & TypeFlags.Union) { + const types = (type as UnionType).types; + const filtered = filter(types, f); + if (filtered === types) { + return type; + } + const origin = (type as UnionType).origin; + let newOrigin: Type | undefined; + if (origin && origin.flags & TypeFlags.Union) { + // If the origin type is a (denormalized) union type, filter its non-union constituents. If that ends + // up removing a smaller number of types than in the normalized constituent set (meaning some of the + // filtered types are within nested unions in the origin), then we can't construct a new origin type. + // Otherwise, if we have exactly one type left in the origin set, return that as the filtered type. + // Otherwise, construct a new filtered origin type. + const originTypes = (origin as UnionType).types; + const originFiltered = filter(originTypes, t => !!(t.flags & TypeFlags.Union) || f(t)); + if (originTypes.length - originFiltered.length === types.length - filtered.length) { + if (originFiltered.length === 1) { + return originFiltered[0]; + } + newOrigin = createOriginUnionOrIntersectionType(TypeFlags.Union, originFiltered); + } + } + // filtering could remove intersections so `ContainsIntersections` might be forwarded "incorrectly" + // it is purely an optimization hint so there is no harm in accidentally forwarding it + return getUnionTypeFromSortedList(filtered, (type as UnionType).objectFlags & (ObjectFlags.PrimitiveUnion | ObjectFlags.ContainsIntersections), /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined, newOrigin); + } + return type.flags & TypeFlags.Never || f(type) ? type : neverType; + } + + function removeType(type: Type, targetType: Type) { + return filterType(type, t => t !== targetType); + } + + function countTypes(type: Type) { + return type.flags & TypeFlags.Union ? (type as UnionType).types.length : 1; + } + + // Apply a mapping function to a type and return the resulting type. If the source type + // is a union type, the mapping function is applied to each constituent type and a union + // of the resulting types is returned. + function mapType(type: Type, mapper: (t: Type) => Type, noReductions?: boolean): Type; + function mapType(type: Type, mapper: (t: Type) => Type | undefined, noReductions?: boolean): Type | undefined; + function mapType(type: Type, mapper: (t: Type) => Type | undefined, noReductions?: boolean): Type | undefined { + if (type.flags & TypeFlags.Never) { + return type; + } + if (!(type.flags & TypeFlags.Union)) { + return mapper(type); + } + const origin = (type as UnionType).origin; + const types = origin && origin.flags & TypeFlags.Union ? (origin as UnionType).types : (type as UnionType).types; + let mappedTypes: Type[] | undefined; + let changed = false; + for (const t of types) { + const mapped = t.flags & TypeFlags.Union ? mapType(t, mapper, noReductions) : mapper(t); + changed ||= t !== mapped; + if (mapped) { + if (!mappedTypes) { + mappedTypes = [mapped]; + } + else { + mappedTypes.push(mapped); + } + } + } + return changed ? mappedTypes && getUnionType(mappedTypes, noReductions ? UnionReduction.None : UnionReduction.Literal) : type; + } + + function mapTypeWithAlias(type: Type, mapper: (t: Type) => Type, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { + return type.flags & TypeFlags.Union && aliasSymbol ? + getUnionType(map((type as UnionType).types, mapper), UnionReduction.Literal, aliasSymbol, aliasTypeArguments) : + mapType(type, mapper); + } + + function extractTypesOfKind(type: Type, kind: TypeFlags) { + return filterType(type, t => (t.flags & kind) !== 0); + } + + // Return a new type in which occurrences of the string, number and bigint primitives and placeholder template + // literal types in typeWithPrimitives have been replaced with occurrences of compatible and more specific types + // from typeWithLiterals. This is essentially a limited form of intersection between the two types. We avoid a + // true intersection because it is more costly and, when applied to union types, generates a large number of + // types we don't actually care about. + function replacePrimitivesWithLiterals(typeWithPrimitives: Type, typeWithLiterals: Type) { + if ( + maybeTypeOfKind(typeWithPrimitives, TypeFlags.String | TypeFlags.TemplateLiteral | TypeFlags.Number | TypeFlags.BigInt) && + maybeTypeOfKind(typeWithLiterals, TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping | TypeFlags.NumberLiteral | TypeFlags.BigIntLiteral) + ) { + return mapType(typeWithPrimitives, t => + t.flags & TypeFlags.String ? extractTypesOfKind(typeWithLiterals, TypeFlags.String | TypeFlags.StringLiteral | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) : + isPatternLiteralType(t) && !maybeTypeOfKind(typeWithLiterals, TypeFlags.String | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) ? extractTypesOfKind(typeWithLiterals, TypeFlags.StringLiteral) : + t.flags & TypeFlags.Number ? extractTypesOfKind(typeWithLiterals, TypeFlags.Number | TypeFlags.NumberLiteral) : + t.flags & TypeFlags.BigInt ? extractTypesOfKind(typeWithLiterals, TypeFlags.BigInt | TypeFlags.BigIntLiteral) : t); + } + return typeWithPrimitives; + } + + function isIncomplete(flowType: FlowType) { + return flowType.flags === 0; + } + + function getTypeFromFlowType(flowType: FlowType) { + return flowType.flags === 0 ? flowType.type : flowType as Type; + } + + function createFlowType(type: Type, incomplete: boolean): FlowType { + return incomplete ? { flags: 0, type: type.flags & TypeFlags.Never ? silentNeverType : type } : type; + } + + // An evolving array type tracks the element types that have so far been seen in an + // 'x.push(value)' or 'x[n] = value' operation along the control flow graph. Evolving + // array types are ultimately converted into manifest array types (using getFinalArrayType) + // and never escape the getFlowTypeOfReference function. + function createEvolvingArrayType(elementType: Type): EvolvingArrayType { + const result = createObjectType(ObjectFlags.EvolvingArray) as EvolvingArrayType; + result.elementType = elementType; + return result; + } + + function getEvolvingArrayType(elementType: Type): EvolvingArrayType { + return evolvingArrayTypes[elementType.id] || (evolvingArrayTypes[elementType.id] = createEvolvingArrayType(elementType)); + } + + // When adding evolving array element types we do not perform subtype reduction. Instead, + // we defer subtype reduction until the evolving array type is finalized into a manifest + // array type. + function addEvolvingArrayElementType(evolvingArrayType: EvolvingArrayType, node: Expression): EvolvingArrayType { + const elementType = getRegularTypeOfObjectLiteral(getBaseTypeOfLiteralType(getContextFreeTypeOfExpression(node))); + return isTypeSubsetOf(elementType, evolvingArrayType.elementType) ? evolvingArrayType : getEvolvingArrayType(getUnionType([evolvingArrayType.elementType, elementType])); + } + + function createFinalArrayType(elementType: Type) { + return elementType.flags & TypeFlags.Never ? + autoArrayType : + createArrayType( + elementType.flags & TypeFlags.Union ? + getUnionType((elementType as UnionType).types, UnionReduction.Subtype) : + elementType, + ); + } + + // We perform subtype reduction upon obtaining the final array type from an evolving array type. + function getFinalArrayType(evolvingArrayType: EvolvingArrayType): Type { + return evolvingArrayType.finalArrayType || (evolvingArrayType.finalArrayType = createFinalArrayType(evolvingArrayType.elementType)); + } + + function finalizeEvolvingArrayType(type: Type): Type { + return getObjectFlags(type) & ObjectFlags.EvolvingArray ? getFinalArrayType(type as EvolvingArrayType) : type; + } + + function getElementTypeOfEvolvingArrayType(type: Type) { + return getObjectFlags(type) & ObjectFlags.EvolvingArray ? (type as EvolvingArrayType).elementType : neverType; + } + + function isEvolvingArrayTypeList(types: Type[]) { + let hasEvolvingArrayType = false; + for (const t of types) { + if (!(t.flags & TypeFlags.Never)) { + if (!(getObjectFlags(t) & ObjectFlags.EvolvingArray)) { + return false; + } + hasEvolvingArrayType = true; + } + } + return hasEvolvingArrayType; + } + + // Return true if the given node is 'x' in an 'x.length', x.push(value)', 'x.unshift(value)' or + // 'x[n] = value' operation, where 'n' is an expression of type any, undefined, or a number-like type. + function isEvolvingArrayOperationTarget(node: Node) { + const root = getReferenceRoot(node); + const parent = root.parent; + const isLengthPushOrUnshift = isPropertyAccessExpression(parent) && ( + parent.name.escapedText === "length" || + parent.parent.kind === SyntaxKind.CallExpression + && isIdentifier(parent.name) + && isPushOrUnshiftIdentifier(parent.name) + ); + const isElementAssignment = parent.kind === SyntaxKind.ElementAccessExpression && + (parent as ElementAccessExpression).expression === root && + parent.parent.kind === SyntaxKind.BinaryExpression && + (parent.parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken && + (parent.parent as BinaryExpression).left === parent && + !isAssignmentTarget(parent.parent) && + isTypeAssignableToKind(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression), TypeFlags.NumberLike); + return isLengthPushOrUnshift || isElementAssignment; + } + + function isDeclarationWithExplicitTypeAnnotation(node: Declaration) { + return (isVariableDeclaration(node) || isPropertyDeclaration(node) || isPropertySignature(node) || isParameter(node)) && + !!(getEffectiveTypeAnnotationNode(node) || + isInJSFile(node) && hasInitializer(node) && node.initializer && isFunctionExpressionOrArrowFunction(node.initializer) && getEffectiveReturnTypeNode(node.initializer)); + } + + function getExplicitTypeOfSymbol(symbol: Symbol, diagnostic?: Diagnostic) { + symbol = resolveSymbol(symbol); + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method | SymbolFlags.Class | SymbolFlags.ValueModule)) { + return getTypeOfSymbol(symbol); + } + if (symbol.flags & (SymbolFlags.Variable | SymbolFlags.Property)) { + if (getCheckFlags(symbol) & CheckFlags.Mapped) { + const origin = (symbol as MappedSymbol).links.syntheticOrigin; + if (origin && getExplicitTypeOfSymbol(origin)) { + return getTypeOfSymbol(symbol); + } + } + const declaration = symbol.valueDeclaration; + if (declaration) { + if (isDeclarationWithExplicitTypeAnnotation(declaration)) { + return getTypeOfSymbol(symbol); + } + if (isVariableDeclaration(declaration) && declaration.parent.parent.kind === SyntaxKind.ForOfStatement) { + const statement = declaration.parent.parent; + const expressionType = getTypeOfDottedName(statement.expression, /*diagnostic*/ undefined); + if (expressionType) { + const use = statement.awaitModifier ? IterationUse.ForAwaitOf : IterationUse.ForOf; + return checkIteratedTypeOrElementType(use, expressionType, undefinedType, /*errorNode*/ undefined); + } + } + if (diagnostic) { + addRelatedInfo(diagnostic, createDiagnosticForNode(declaration, Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol))); + } + } + } + } + + // We require the dotted function name in an assertion expression to be comprised of identifiers + // that reference function, method, class or value module symbols; or variable, property or + // parameter symbols with declarations that have explicit type annotations. Such references are + // resolvable with no possibility of triggering circularities in control flow analysis. + function getTypeOfDottedName(node: Expression, diagnostic: Diagnostic | undefined): Type | undefined { + if (!(node.flags & NodeFlags.InWithStatement)) { + switch (node.kind) { + case SyntaxKind.Identifier: + const symbol = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(node as Identifier)); + return getExplicitTypeOfSymbol(symbol, diagnostic); + case SyntaxKind.ThisKeyword: + return getExplicitThisType(node); + case SyntaxKind.SuperKeyword: + return checkSuperExpression(node); + case SyntaxKind.PropertyAccessExpression: { + const type = getTypeOfDottedName((node as PropertyAccessExpression).expression, diagnostic); + if (type) { + const name = (node as PropertyAccessExpression).name; + let prop: Symbol | undefined; + if (isPrivateIdentifier(name)) { + if (!type.symbol) { + return undefined; + } + prop = getPropertyOfType(type, getSymbolNameForPrivateIdentifier(type.symbol, name.escapedText)); + } + else { + prop = getPropertyOfType(type, name.escapedText); + } + return prop && getExplicitTypeOfSymbol(prop, diagnostic); + } + return undefined; + } + case SyntaxKind.ParenthesizedExpression: + return getTypeOfDottedName((node as ParenthesizedExpression).expression, diagnostic); + } + } + } + + function getEffectsSignature(node: CallExpression | InstanceofExpression) { + const links = getNodeLinks(node); + let signature = links.effectsSignature; + if (signature === undefined) { + // A call expression parented by an expression statement is a potential assertion. Other call + // expressions are potential type predicate function calls. In order to avoid triggering + // circularities in control flow analysis, we use getTypeOfDottedName when resolving the call + // target expression of an assertion. + let funcType: Type | undefined; + if (isBinaryExpression(node)) { + const rightType = checkNonNullExpression(node.right); + funcType = getSymbolHasInstanceMethodOfObjectType(rightType); + } + else if (node.parent.kind === SyntaxKind.ExpressionStatement) { + funcType = getTypeOfDottedName(node.expression, /*diagnostic*/ undefined); + } + else if (node.expression.kind !== SyntaxKind.SuperKeyword) { + if (isOptionalChain(node)) { + funcType = checkNonNullType( + getOptionalExpressionType(checkExpression(node.expression), node.expression), + node.expression, + ); + } + else { + funcType = checkNonNullExpression(node.expression); + } + } + const signatures = getSignaturesOfType(funcType && getApparentType(funcType) || unknownType, SignatureKind.Call); + const candidate = signatures.length === 1 && !signatures[0].typeParameters ? signatures[0] : + some(signatures, hasTypePredicateOrNeverReturnType) ? getResolvedSignature(node) : + undefined; + signature = links.effectsSignature = candidate && hasTypePredicateOrNeverReturnType(candidate) ? candidate : unknownSignature; + } + return signature === unknownSignature ? undefined : signature; + } + + function hasTypePredicateOrNeverReturnType(signature: Signature) { + return !!(getTypePredicateOfSignature(signature) || + signature.declaration && (getReturnTypeFromAnnotation(signature.declaration) || unknownType).flags & TypeFlags.Never); + } + + function getTypePredicateArgument(predicate: TypePredicate, callExpression: CallExpression) { + if (predicate.kind === TypePredicateKind.Identifier || predicate.kind === TypePredicateKind.AssertsIdentifier) { + return callExpression.arguments[predicate.parameterIndex]; + } + const invokedExpression = skipParentheses(callExpression.expression); + return isAccessExpression(invokedExpression) ? skipParentheses(invokedExpression.expression) : undefined; + } + + function reportFlowControlError(node: Node) { + const block = findAncestor(node, isFunctionOrModuleBlock) as Block | ModuleBlock | SourceFile; + const sourceFile = getSourceFileOfNode(node); + const span = getSpanOfTokenAtPosition(sourceFile, block.statements.pos); + diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.The_containing_function_or_module_body_is_too_large_for_control_flow_analysis)); + } + + function isReachableFlowNode(flow: FlowNode) { + const result = isReachableFlowNodeWorker(flow, /*noCacheCheck*/ false); + lastFlowNode = flow; + lastFlowNodeReachable = result; + return result; + } + + function isFalseExpression(expr: Expression): boolean { + const node = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + return node.kind === SyntaxKind.FalseKeyword || node.kind === SyntaxKind.BinaryExpression && ( + (node as BinaryExpression).operatorToken.kind === SyntaxKind.AmpersandAmpersandToken && (isFalseExpression((node as BinaryExpression).left) || isFalseExpression((node as BinaryExpression).right)) || + (node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken && isFalseExpression((node as BinaryExpression).left) && isFalseExpression((node as BinaryExpression).right) + ); + } + + function isReachableFlowNodeWorker(flow: FlowNode, noCacheCheck: boolean): boolean { + while (true) { + if (flow === lastFlowNode) { + return lastFlowNodeReachable; + } + const flags = flow.flags; + if (flags & FlowFlags.Shared) { + if (!noCacheCheck) { + const id = getFlowNodeId(flow); + const reachable = flowNodeReachable[id]; + return reachable !== undefined ? reachable : (flowNodeReachable[id] = isReachableFlowNodeWorker(flow, /*noCacheCheck*/ true)); + } + noCacheCheck = false; + } + if (flags & (FlowFlags.Assignment | FlowFlags.Condition | FlowFlags.ArrayMutation)) { + flow = (flow as FlowAssignment | FlowCondition | FlowArrayMutation).antecedent; + } + else if (flags & FlowFlags.Call) { + const signature = getEffectsSignature((flow as FlowCall).node); + if (signature) { + const predicate = getTypePredicateOfSignature(signature); + if (predicate && predicate.kind === TypePredicateKind.AssertsIdentifier && !predicate.type) { + const predicateArgument = (flow as FlowCall).node.arguments[predicate.parameterIndex]; + if (predicateArgument && isFalseExpression(predicateArgument)) { + return false; + } + } + if (getReturnTypeOfSignature(signature).flags & TypeFlags.Never) { + return false; + } + } + flow = (flow as FlowCall).antecedent; + } + else if (flags & FlowFlags.BranchLabel) { + // A branching point is reachable if any branch is reachable. + return some((flow as FlowLabel).antecedent, f => isReachableFlowNodeWorker(f, /*noCacheCheck*/ false)); + } + else if (flags & FlowFlags.LoopLabel) { + const antecedents = (flow as FlowLabel).antecedent; + if (antecedents === undefined || antecedents.length === 0) { + return false; + } + // A loop is reachable if the control flow path that leads to the top is reachable. + flow = antecedents[0]; + } + else if (flags & FlowFlags.SwitchClause) { + // The control flow path representing an unmatched value in a switch statement with + // no default clause is unreachable if the switch statement is exhaustive. + const data = (flow as FlowSwitchClause).node; + if (data.clauseStart === data.clauseEnd && isExhaustiveSwitchStatement(data.switchStatement)) { + return false; + } + flow = (flow as FlowSwitchClause).antecedent; + } + else if (flags & FlowFlags.ReduceLabel) { + // Cache is unreliable once we start adjusting labels + lastFlowNode = undefined; + const target = (flow as FlowReduceLabel).node.target; + const saveAntecedents = target.antecedent; + target.antecedent = (flow as FlowReduceLabel).node.antecedents; + const result = isReachableFlowNodeWorker((flow as FlowReduceLabel).antecedent, /*noCacheCheck*/ false); + target.antecedent = saveAntecedents; + return result; + } + else { + return !(flags & FlowFlags.Unreachable); + } + } + } + + // Return true if the given flow node is preceded by a 'super(...)' call in every possible code path + // leading to the node. + function isPostSuperFlowNode(flow: FlowNode, noCacheCheck: boolean): boolean { + while (true) { + const flags = flow.flags; + if (flags & FlowFlags.Shared) { + if (!noCacheCheck) { + const id = getFlowNodeId(flow); + const postSuper = flowNodePostSuper[id]; + return postSuper !== undefined ? postSuper : (flowNodePostSuper[id] = isPostSuperFlowNode(flow, /*noCacheCheck*/ true)); + } + noCacheCheck = false; + } + if (flags & (FlowFlags.Assignment | FlowFlags.Condition | FlowFlags.ArrayMutation | FlowFlags.SwitchClause)) { + flow = (flow as FlowAssignment | FlowCondition | FlowArrayMutation | FlowSwitchClause).antecedent; + } + else if (flags & FlowFlags.Call) { + if ((flow as FlowCall).node.expression.kind === SyntaxKind.SuperKeyword) { + return true; + } + flow = (flow as FlowCall).antecedent; + } + else if (flags & FlowFlags.BranchLabel) { + // A branching point is post-super if every branch is post-super. + return every((flow as FlowLabel).antecedent, f => isPostSuperFlowNode(f, /*noCacheCheck*/ false)); + } + else if (flags & FlowFlags.LoopLabel) { + // A loop is post-super if the control flow path that leads to the top is post-super. + flow = (flow as FlowLabel).antecedent![0]; + } + else if (flags & FlowFlags.ReduceLabel) { + const target = (flow as FlowReduceLabel).node.target; + const saveAntecedents = target.antecedent; + target.antecedent = (flow as FlowReduceLabel).node.antecedents; + const result = isPostSuperFlowNode((flow as FlowReduceLabel).antecedent, /*noCacheCheck*/ false); + target.antecedent = saveAntecedents; + return result; + } + else { + // Unreachable nodes are considered post-super to silence errors + return !!(flags & FlowFlags.Unreachable); + } + } + } + + function isConstantReference(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.ThisKeyword: + return true; + case SyntaxKind.Identifier: + if (!isThisInTypeQuery(node)) { + const symbol = getResolvedSymbol(node as Identifier); + return isConstantVariable(symbol) + || isParameterOrMutableLocalVariable(symbol) && !isSymbolAssigned(symbol) + || !!symbol.valueDeclaration && isFunctionExpression(symbol.valueDeclaration); + } + break; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + // The resolvedSymbol property is initialized by checkPropertyAccess or checkElementAccess before we get here. + return isConstantReference((node as AccessExpression).expression) && isReadonlySymbol(getNodeLinks(node).resolvedSymbol || unknownSymbol); + case SyntaxKind.ObjectBindingPattern: + case SyntaxKind.ArrayBindingPattern: + const rootDeclaration = getRootDeclaration(node.parent); + return isParameter(rootDeclaration) || isCatchClauseVariableDeclaration(rootDeclaration) + ? !isSomeSymbolAssigned(rootDeclaration) + : isVariableDeclaration(rootDeclaration) && isVarConstLike(rootDeclaration); + } + return false; + } + + function getFlowTypeOfReference(reference: Node, declaredType: Type, initialType = declaredType, flowContainer?: Node, flowNode = tryCast(reference, canHaveFlowNode)?.flowNode) { + let key: string | undefined; + let isKeySet = false; + let flowDepth = 0; + if (flowAnalysisDisabled) { + return errorType; + } + if (!flowNode) { + return declaredType; + } + flowInvocationCount++; + const sharedFlowStart = sharedFlowCount; + const evolvedType = getTypeFromFlowType(getTypeAtFlowNode(flowNode)); + sharedFlowCount = sharedFlowStart; + // When the reference is 'x' in an 'x.length', 'x.push(value)', 'x.unshift(value)' or x[n] = value' operation, + // we give type 'any[]' to 'x' instead of using the type determined by control flow analysis such that operations + // on empty arrays are possible without implicit any errors and new element types can be inferred without + // type mismatch errors. + const resultType = getObjectFlags(evolvedType) & ObjectFlags.EvolvingArray && isEvolvingArrayOperationTarget(reference) ? autoArrayType : finalizeEvolvingArrayType(evolvedType); + if (resultType === unreachableNeverType || reference.parent && reference.parent.kind === SyntaxKind.NonNullExpression && !(resultType.flags & TypeFlags.Never) && getTypeWithFacts(resultType, TypeFacts.NEUndefinedOrNull).flags & TypeFlags.Never) { + return declaredType; + } + return resultType; + + function getOrSetCacheKey() { + if (isKeySet) { + return key; + } + isKeySet = true; + return key = getFlowCacheKey(reference, declaredType, initialType, flowContainer); + } + + function getTypeAtFlowNode(flow: FlowNode): FlowType { + if (flowDepth === 2000) { + // We have made 2000 recursive invocations. To avoid overflowing the call stack we report an error + // and disable further control flow analysis in the containing function or module body. + tracing?.instant(tracing.Phase.CheckTypes, "getTypeAtFlowNode_DepthLimit", { flowId: flow.id }); + flowAnalysisDisabled = true; + reportFlowControlError(reference); + return errorType; + } + flowDepth++; + let sharedFlow: FlowNode | undefined; + while (true) { + const flags = flow.flags; + if (flags & FlowFlags.Shared) { + // We cache results of flow type resolution for shared nodes that were previously visited in + // the same getFlowTypeOfReference invocation. A node is considered shared when it is the + // antecedent of more than one node. + for (let i = sharedFlowStart; i < sharedFlowCount; i++) { + if (sharedFlowNodes[i] === flow) { + flowDepth--; + return sharedFlowTypes[i]; + } + } + sharedFlow = flow; + } + let type: FlowType | undefined; + if (flags & FlowFlags.Assignment) { + type = getTypeAtFlowAssignment(flow as FlowAssignment); + if (!type) { + flow = (flow as FlowAssignment).antecedent; + continue; + } + } + else if (flags & FlowFlags.Call) { + type = getTypeAtFlowCall(flow as FlowCall); + if (!type) { + flow = (flow as FlowCall).antecedent; + continue; + } + } + else if (flags & FlowFlags.Condition) { + type = getTypeAtFlowCondition(flow as FlowCondition); + } + else if (flags & FlowFlags.SwitchClause) { + type = getTypeAtSwitchClause(flow as FlowSwitchClause); + } + else if (flags & FlowFlags.Label) { + if ((flow as FlowLabel).antecedent!.length === 1) { + flow = (flow as FlowLabel).antecedent![0]; + continue; + } + type = flags & FlowFlags.BranchLabel ? + getTypeAtFlowBranchLabel(flow as FlowLabel) : + getTypeAtFlowLoopLabel(flow as FlowLabel); + } + else if (flags & FlowFlags.ArrayMutation) { + type = getTypeAtFlowArrayMutation(flow as FlowArrayMutation); + if (!type) { + flow = (flow as FlowArrayMutation).antecedent; + continue; + } + } + else if (flags & FlowFlags.ReduceLabel) { + const target = (flow as FlowReduceLabel).node.target; + const saveAntecedents = target.antecedent; + target.antecedent = (flow as FlowReduceLabel).node.antecedents; + type = getTypeAtFlowNode((flow as FlowReduceLabel).antecedent); + target.antecedent = saveAntecedents; + } + else if (flags & FlowFlags.Start) { + // Check if we should continue with the control flow of the containing function. + const container = (flow as FlowStart).node; + if ( + container && container !== flowContainer && + reference.kind !== SyntaxKind.PropertyAccessExpression && + reference.kind !== SyntaxKind.ElementAccessExpression && + !(reference.kind === SyntaxKind.ThisKeyword && container.kind !== SyntaxKind.ArrowFunction) + ) { + flow = container.flowNode!; + continue; + } + // At the top of the flow we have the initial type. + type = initialType; + } + else { + // Unreachable code errors are reported in the binding phase. Here we + // simply return the non-auto declared type to reduce follow-on errors. + type = convertAutoToAny(declaredType); + } + if (sharedFlow) { + // Record visited node and the associated type in the cache. + sharedFlowNodes[sharedFlowCount] = sharedFlow; + sharedFlowTypes[sharedFlowCount] = type; + sharedFlowCount++; + } + flowDepth--; + return type; + } + } + + function getInitialOrAssignedType(flow: FlowAssignment) { + const node = flow.node; + return getNarrowableTypeForReference( + node.kind === SyntaxKind.VariableDeclaration || node.kind === SyntaxKind.BindingElement ? + getInitialType(node as VariableDeclaration | BindingElement) : + getAssignedType(node), + reference, + ); + } + + function getTypeAtFlowAssignment(flow: FlowAssignment) { + const node = flow.node; + // Assignments only narrow the computed type if the declared type is a union type. Thus, we + // only need to evaluate the assigned type if the declared type is a union type. + if (isMatchingReference(reference, node)) { + if (!isReachableFlowNode(flow)) { + return unreachableNeverType; + } + if (getAssignmentTargetKind(node) === AssignmentKind.Compound) { + const flowType = getTypeAtFlowNode(flow.antecedent); + return createFlowType(getBaseTypeOfLiteralType(getTypeFromFlowType(flowType)), isIncomplete(flowType)); + } + if (declaredType === autoType || declaredType === autoArrayType) { + if (isEmptyArrayAssignment(node)) { + return getEvolvingArrayType(neverType); + } + const assignedType = getWidenedLiteralType(getInitialOrAssignedType(flow)); + return isTypeAssignableTo(assignedType, declaredType) ? assignedType : anyArrayType; + } + const t = isInCompoundLikeAssignment(node) ? getBaseTypeOfLiteralType(declaredType) : declaredType; + if (t.flags & TypeFlags.Union) { + return getAssignmentReducedType(t as UnionType, getInitialOrAssignedType(flow)); + } + return t; + } + // We didn't have a direct match. However, if the reference is a dotted name, this + // may be an assignment to a left hand part of the reference. For example, for a + // reference 'x.y.z', we may be at an assignment to 'x.y' or 'x'. In that case, + // return the declared type. + if (containsMatchingReference(reference, node)) { + if (!isReachableFlowNode(flow)) { + return unreachableNeverType; + } + // A matching dotted name might also be an expando property on a function *expression*, + // in which case we continue control flow analysis back to the function's declaration + if (isVariableDeclaration(node) && (isInJSFile(node) || isVarConstLike(node))) { + const init = getDeclaredExpandoInitializer(node); + if (init && (init.kind === SyntaxKind.FunctionExpression || init.kind === SyntaxKind.ArrowFunction)) { + return getTypeAtFlowNode(flow.antecedent); + } + } + return declaredType; + } + // for (const _ in ref) acts as a nonnull on ref + if ( + isVariableDeclaration(node) && + node.parent.parent.kind === SyntaxKind.ForInStatement && + (isMatchingReference(reference, node.parent.parent.expression) || optionalChainContainsReference(node.parent.parent.expression, reference)) + ) { + return getNonNullableTypeIfNeeded(finalizeEvolvingArrayType(getTypeFromFlowType(getTypeAtFlowNode(flow.antecedent)))); + } + // Assignment doesn't affect reference + return undefined; + } + + function narrowTypeByAssertion(type: Type, expr: Expression): Type { + const node = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + if (node.kind === SyntaxKind.FalseKeyword) { + return unreachableNeverType; + } + if (node.kind === SyntaxKind.BinaryExpression) { + if ((node as BinaryExpression).operatorToken.kind === SyntaxKind.AmpersandAmpersandToken) { + return narrowTypeByAssertion(narrowTypeByAssertion(type, (node as BinaryExpression).left), (node as BinaryExpression).right); + } + if ((node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken) { + return getUnionType([narrowTypeByAssertion(type, (node as BinaryExpression).left), narrowTypeByAssertion(type, (node as BinaryExpression).right)]); + } + } + return narrowType(type, node, /*assumeTrue*/ true); + } + + function getTypeAtFlowCall(flow: FlowCall): FlowType | undefined { + const signature = getEffectsSignature(flow.node); + if (signature) { + const predicate = getTypePredicateOfSignature(signature); + if (predicate && (predicate.kind === TypePredicateKind.AssertsThis || predicate.kind === TypePredicateKind.AssertsIdentifier)) { + const flowType = getTypeAtFlowNode(flow.antecedent); + const type = finalizeEvolvingArrayType(getTypeFromFlowType(flowType)); + const narrowedType = predicate.type ? narrowTypeByTypePredicate(type, predicate, flow.node, /*assumeTrue*/ true) : + predicate.kind === TypePredicateKind.AssertsIdentifier && predicate.parameterIndex >= 0 && predicate.parameterIndex < flow.node.arguments.length ? narrowTypeByAssertion(type, flow.node.arguments[predicate.parameterIndex]) : + type; + return narrowedType === type ? flowType : createFlowType(narrowedType, isIncomplete(flowType)); + } + if (getReturnTypeOfSignature(signature).flags & TypeFlags.Never) { + return unreachableNeverType; + } + } + return undefined; + } + + function getTypeAtFlowArrayMutation(flow: FlowArrayMutation): FlowType | undefined { + if (declaredType === autoType || declaredType === autoArrayType) { + const node = flow.node; + const expr = node.kind === SyntaxKind.CallExpression ? + (node.expression as PropertyAccessExpression).expression : + (node.left as ElementAccessExpression).expression; + if (isMatchingReference(reference, getReferenceCandidate(expr))) { + const flowType = getTypeAtFlowNode(flow.antecedent); + const type = getTypeFromFlowType(flowType); + if (getObjectFlags(type) & ObjectFlags.EvolvingArray) { + let evolvedType = type as EvolvingArrayType; + if (node.kind === SyntaxKind.CallExpression) { + for (const arg of node.arguments) { + evolvedType = addEvolvingArrayElementType(evolvedType, arg); + } + } + else { + // We must get the context free expression type so as to not recur in an uncached fashion on the LHS (which causes exponential blowup in compile time) + const indexType = getContextFreeTypeOfExpression((node.left as ElementAccessExpression).argumentExpression); + if (isTypeAssignableToKind(indexType, TypeFlags.NumberLike)) { + evolvedType = addEvolvingArrayElementType(evolvedType, node.right); + } + } + return evolvedType === type ? flowType : createFlowType(evolvedType, isIncomplete(flowType)); + } + return flowType; + } + } + return undefined; + } + + function getTypeAtFlowCondition(flow: FlowCondition): FlowType { + const flowType = getTypeAtFlowNode(flow.antecedent); + const type = getTypeFromFlowType(flowType); + if (type.flags & TypeFlags.Never) { + return flowType; + } + // If we have an antecedent type (meaning we're reachable in some way), we first + // attempt to narrow the antecedent type. If that produces the never type, and if + // the antecedent type is incomplete (i.e. a transient type in a loop), then we + // take the type guard as an indication that control *could* reach here once we + // have the complete type. We proceed by switching to the silent never type which + // doesn't report errors when operators are applied to it. Note that this is the + // *only* place a silent never type is ever generated. + const assumeTrue = (flow.flags & FlowFlags.TrueCondition) !== 0; + const nonEvolvingType = finalizeEvolvingArrayType(type); + const narrowedType = narrowType(nonEvolvingType, flow.node, assumeTrue); + if (narrowedType === nonEvolvingType) { + return flowType; + } + return createFlowType(narrowedType, isIncomplete(flowType)); + } + + function getTypeAtSwitchClause(flow: FlowSwitchClause): FlowType { + const expr = skipParentheses(flow.node.switchStatement.expression); + const flowType = getTypeAtFlowNode(flow.antecedent); + let type = getTypeFromFlowType(flowType); + if (isMatchingReference(reference, expr)) { + type = narrowTypeBySwitchOnDiscriminant(type, flow.node); + } + else if (expr.kind === SyntaxKind.TypeOfExpression && isMatchingReference(reference, (expr as TypeOfExpression).expression)) { + type = narrowTypeBySwitchOnTypeOf(type, flow.node); + } + else if (expr.kind === SyntaxKind.TrueKeyword) { + type = narrowTypeBySwitchOnTrue(type, flow.node); + } + else { + if (strictNullChecks) { + if (optionalChainContainsReference(expr, reference)) { + type = narrowTypeBySwitchOptionalChainContainment(type, flow.node, t => !(t.flags & (TypeFlags.Undefined | TypeFlags.Never))); + } + else if (expr.kind === SyntaxKind.TypeOfExpression && optionalChainContainsReference((expr as TypeOfExpression).expression, reference)) { + type = narrowTypeBySwitchOptionalChainContainment(type, flow.node, t => !(t.flags & TypeFlags.Never || t.flags & TypeFlags.StringLiteral && (t as StringLiteralType).value === "undefined")); + } + } + const access = getDiscriminantPropertyAccess(expr, type); + if (access) { + type = narrowTypeBySwitchOnDiscriminantProperty(type, access, flow.node); + } + } + return createFlowType(type, isIncomplete(flowType)); + } + + function getTypeAtFlowBranchLabel(flow: FlowLabel): FlowType { + const antecedentTypes: Type[] = []; + let subtypeReduction = false; + let seenIncomplete = false; + let bypassFlow: FlowSwitchClause | undefined; + for (const antecedent of flow.antecedent!) { + if (!bypassFlow && antecedent.flags & FlowFlags.SwitchClause && (antecedent as FlowSwitchClause).node.clauseStart === (antecedent as FlowSwitchClause).node.clauseEnd) { + // The antecedent is the bypass branch of a potentially exhaustive switch statement. + bypassFlow = antecedent as FlowSwitchClause; + continue; + } + const flowType = getTypeAtFlowNode(antecedent); + const type = getTypeFromFlowType(flowType); + // If the type at a particular antecedent path is the declared type and the + // reference is known to always be assigned (i.e. when declared and initial types + // are the same), there is no reason to process more antecedents since the only + // possible outcome is subtypes that will be removed in the final union type anyway. + if (type === declaredType && declaredType === initialType) { + return type; + } + pushIfUnique(antecedentTypes, type); + // If an antecedent type is not a subset of the declared type, we need to perform + // subtype reduction. This happens when a "foreign" type is injected into the control + // flow using the instanceof operator or a user defined type predicate. + if (!isTypeSubsetOf(type, initialType)) { + subtypeReduction = true; + } + if (isIncomplete(flowType)) { + seenIncomplete = true; + } + } + if (bypassFlow) { + const flowType = getTypeAtFlowNode(bypassFlow); + const type = getTypeFromFlowType(flowType); + // If the bypass flow contributes a type we haven't seen yet and the switch statement + // isn't exhaustive, process the bypass flow type. Since exhaustiveness checks increase + // the risk of circularities, we only want to perform them when they make a difference. + if (!(type.flags & TypeFlags.Never) && !contains(antecedentTypes, type) && !isExhaustiveSwitchStatement(bypassFlow.node.switchStatement)) { + if (type === declaredType && declaredType === initialType) { + return type; + } + antecedentTypes.push(type); + if (!isTypeSubsetOf(type, initialType)) { + subtypeReduction = true; + } + if (isIncomplete(flowType)) { + seenIncomplete = true; + } + } + } + return createFlowType(getUnionOrEvolvingArrayType(antecedentTypes, subtypeReduction ? UnionReduction.Subtype : UnionReduction.Literal), seenIncomplete); + } + + function getTypeAtFlowLoopLabel(flow: FlowLabel): FlowType { + // If we have previously computed the control flow type for the reference at + // this flow loop junction, return the cached type. + const id = getFlowNodeId(flow); + const cache = flowLoopCaches[id] || (flowLoopCaches[id] = new Map()); + const key = getOrSetCacheKey(); + if (!key) { + // No cache key is generated when binding patterns are in unnarrowable situations + return declaredType; + } + const cached = cache.get(key); + if (cached) { + return cached; + } + // If this flow loop junction and reference are already being processed, return + // the union of the types computed for each branch so far, marked as incomplete. + // It is possible to see an empty array in cases where loops are nested and the + // back edge of the outer loop reaches an inner loop that is already being analyzed. + // In such cases we restart the analysis of the inner loop, which will then see + // a non-empty in-process array for the outer loop and eventually terminate because + // the first antecedent of a loop junction is always the non-looping control flow + // path that leads to the top. + for (let i = flowLoopStart; i < flowLoopCount; i++) { + if (flowLoopNodes[i] === flow && flowLoopKeys[i] === key && flowLoopTypes[i].length) { + return createFlowType(getUnionOrEvolvingArrayType(flowLoopTypes[i], UnionReduction.Literal), /*incomplete*/ true); + } + } + // Add the flow loop junction and reference to the in-process stack and analyze + // each antecedent code path. + const antecedentTypes: Type[] = []; + let subtypeReduction = false; + let firstAntecedentType: FlowType | undefined; + for (const antecedent of flow.antecedent!) { + let flowType; + if (!firstAntecedentType) { + // The first antecedent of a loop junction is always the non-looping control + // flow path that leads to the top. + flowType = firstAntecedentType = getTypeAtFlowNode(antecedent); + } + else { + // All but the first antecedent are the looping control flow paths that lead + // back to the loop junction. We track these on the flow loop stack. + flowLoopNodes[flowLoopCount] = flow; + flowLoopKeys[flowLoopCount] = key; + flowLoopTypes[flowLoopCount] = antecedentTypes; + flowLoopCount++; + const saveFlowTypeCache = flowTypeCache; + flowTypeCache = undefined; + flowType = getTypeAtFlowNode(antecedent); + flowTypeCache = saveFlowTypeCache; + flowLoopCount--; + // If we see a value appear in the cache it is a sign that control flow analysis + // was restarted and completed by checkExpressionCached. We can simply pick up + // the resulting type and bail out. + const cached = cache.get(key); + if (cached) { + return cached; + } + } + const type = getTypeFromFlowType(flowType); + pushIfUnique(antecedentTypes, type); + // If an antecedent type is not a subset of the declared type, we need to perform + // subtype reduction. This happens when a "foreign" type is injected into the control + // flow using the instanceof operator or a user defined type predicate. + if (!isTypeSubsetOf(type, initialType)) { + subtypeReduction = true; + } + // If the type at a particular antecedent path is the declared type there is no + // reason to process more antecedents since the only possible outcome is subtypes + // that will be removed in the final union type anyway. + if (type === declaredType) { + break; + } + } + // The result is incomplete if the first antecedent (the non-looping control flow path) + // is incomplete. + const result = getUnionOrEvolvingArrayType(antecedentTypes, subtypeReduction ? UnionReduction.Subtype : UnionReduction.Literal); + if (isIncomplete(firstAntecedentType!)) { + return createFlowType(result, /*incomplete*/ true); + } + cache.set(key, result); + return result; + } + + // At flow control branch or loop junctions, if the type along every antecedent code path + // is an evolving array type, we construct a combined evolving array type. Otherwise we + // finalize all evolving array types. + function getUnionOrEvolvingArrayType(types: Type[], subtypeReduction: UnionReduction) { + if (isEvolvingArrayTypeList(types)) { + return getEvolvingArrayType(getUnionType(map(types, getElementTypeOfEvolvingArrayType))); + } + const result = recombineUnknownType(getUnionType(sameMap(types, finalizeEvolvingArrayType), subtypeReduction)); + if (result !== declaredType && result.flags & declaredType.flags & TypeFlags.Union && arraysEqual((result as UnionType).types, (declaredType as UnionType).types)) { + return declaredType; + } + return result; + } + + function getCandidateDiscriminantPropertyAccess(expr: Expression) { + if (isBindingPattern(reference) || isFunctionExpressionOrArrowFunction(reference) || isObjectLiteralMethod(reference)) { + // When the reference is a binding pattern or function or arrow expression, we are narrowing a pesudo-reference in + // getNarrowedTypeOfSymbol. An identifier for a destructuring variable declared in the same binding pattern or + // parameter declared in the same parameter list is a candidate. + if (isIdentifier(expr)) { + const symbol = getResolvedSymbol(expr); + const declaration = symbol.valueDeclaration; + if (declaration && (isBindingElement(declaration) || isParameter(declaration)) && reference === declaration.parent && !declaration.initializer && !declaration.dotDotDotToken) { + return declaration; + } + } + } + else if (isAccessExpression(expr)) { + // An access expression is a candidate if the reference matches the left hand expression. + if (isMatchingReference(reference, expr.expression)) { + return expr; + } + } + else if (isIdentifier(expr)) { + const symbol = getResolvedSymbol(expr); + if (isConstantVariable(symbol)) { + const declaration = symbol.valueDeclaration!; + // Given 'const x = obj.kind', allow 'x' as an alias for 'obj.kind' + if ( + isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && isAccessExpression(declaration.initializer) && + isMatchingReference(reference, declaration.initializer.expression) + ) { + return declaration.initializer; + } + // Given 'const { kind: x } = obj', allow 'x' as an alias for 'obj.kind' + if (isBindingElement(declaration) && !declaration.initializer) { + const parent = declaration.parent.parent; + if ( + isVariableDeclaration(parent) && !parent.type && parent.initializer && (isIdentifier(parent.initializer) || isAccessExpression(parent.initializer)) && + isMatchingReference(reference, parent.initializer) + ) { + return declaration; + } + } + } + } + return undefined; + } + + function getDiscriminantPropertyAccess(expr: Expression, computedType: Type) { + // As long as the computed type is a subset of the declared type, we use the full declared type to detect + // a discriminant property. In cases where the computed type isn't a subset, e.g because of a preceding type + // predicate narrowing, we use the actual computed type. + if (declaredType.flags & TypeFlags.Union || computedType.flags & TypeFlags.Union) { + const access = getCandidateDiscriminantPropertyAccess(expr); + if (access) { + const name = getAccessedPropertyName(access); + if (name) { + const type = declaredType.flags & TypeFlags.Union && isTypeSubsetOf(computedType, declaredType) ? declaredType : computedType; + if (isDiscriminantProperty(type, name)) { + return access; + } + } + } + } + return undefined; + } + + function narrowTypeByDiscriminant(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, narrowType: (t: Type) => Type): Type { + const propName = getAccessedPropertyName(access); + if (propName === undefined) { + return type; + } + const optionalChain = isOptionalChain(access); + const removeNullable = strictNullChecks && (optionalChain || isNonNullAccess(access)) && maybeTypeOfKind(type, TypeFlags.Nullable); + let propType = getTypeOfPropertyOfType(removeNullable ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type, propName); + if (!propType) { + return type; + } + propType = removeNullable && optionalChain ? getOptionalType(propType) : propType; + const narrowedPropType = narrowType(propType); + return filterType(type, t => { + const discriminantType = getTypeOfPropertyOrIndexSignatureOfType(t, propName) || unknownType; + return !(discriminantType.flags & TypeFlags.Never) && !(narrowedPropType.flags & TypeFlags.Never) && areTypesComparable(narrowedPropType, discriminantType); + }); + } + + function narrowTypeByDiscriminantProperty(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, operator: SyntaxKind, value: Expression, assumeTrue: boolean) { + if ((operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) && type.flags & TypeFlags.Union) { + const keyPropertyName = getKeyPropertyName(type as UnionType); + if (keyPropertyName && keyPropertyName === getAccessedPropertyName(access)) { + const candidate = getConstituentTypeForKeyType(type as UnionType, getTypeOfExpression(value)); + if (candidate) { + return operator === (assumeTrue ? SyntaxKind.EqualsEqualsEqualsToken : SyntaxKind.ExclamationEqualsEqualsToken) ? candidate : + isUnitType(getTypeOfPropertyOfType(candidate, keyPropertyName) || unknownType) ? removeType(type, candidate) : + type; + } + } + } + return narrowTypeByDiscriminant(type, access, t => narrowTypeByEquality(t, operator, value, assumeTrue)); + } + + function narrowTypeBySwitchOnDiscriminantProperty(type: Type, access: AccessExpression | BindingElement | ParameterDeclaration, data: FlowSwitchClauseData) { + if (data.clauseStart < data.clauseEnd && type.flags & TypeFlags.Union && getKeyPropertyName(type as UnionType) === getAccessedPropertyName(access)) { + const clauseTypes = getSwitchClauseTypes(data.switchStatement).slice(data.clauseStart, data.clauseEnd); + const candidate = getUnionType(map(clauseTypes, t => getConstituentTypeForKeyType(type as UnionType, t) || unknownType)); + if (candidate !== unknownType) { + return candidate; + } + } + return narrowTypeByDiscriminant(type, access, t => narrowTypeBySwitchOnDiscriminant(t, data)); + } + + function narrowTypeByTruthiness(type: Type, expr: Expression, assumeTrue: boolean): Type { + if (isMatchingReference(reference, expr)) { + return getAdjustedTypeWithFacts(type, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy); + } + if (strictNullChecks && assumeTrue && optionalChainContainsReference(expr, reference)) { + type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + const access = getDiscriminantPropertyAccess(expr, type); + if (access) { + return narrowTypeByDiscriminant(type, access, t => getTypeWithFacts(t, assumeTrue ? TypeFacts.Truthy : TypeFacts.Falsy)); + } + return type; + } + + function isTypePresencePossible(type: Type, propName: __String, assumeTrue: boolean) { + const prop = getPropertyOfType(type, propName); + return prop ? + !!(prop.flags & SymbolFlags.Optional || getCheckFlags(prop) & CheckFlags.Partial) || assumeTrue : + !!getApplicableIndexInfoForName(type, propName) || !assumeTrue; + } + + function narrowTypeByInKeyword(type: Type, nameType: StringLiteralType | NumberLiteralType | UniqueESSymbolType, assumeTrue: boolean) { + const name = getPropertyNameFromType(nameType); + const isKnownProperty = someType(type, t => isTypePresencePossible(t, name, /*assumeTrue*/ true)); + if (isKnownProperty) { + // If the check is for a known property (i.e. a property declared in some constituent of + // the target type), we filter the target type by presence of absence of the property. + return filterType(type, t => isTypePresencePossible(t, name, assumeTrue)); + } + if (assumeTrue) { + // If the check is for an unknown property, we intersect the target type with `Record`, + // where X is the name of the property. + const recordSymbol = getGlobalRecordSymbol(); + if (recordSymbol) { + return getIntersectionType([type, getTypeAliasInstantiation(recordSymbol, [nameType, unknownType])]); + } + } + return type; + } + + function narrowTypeByBooleanComparison(type: Type, expr: Expression, bool: BooleanLiteral, operator: BinaryOperator, assumeTrue: boolean): Type { + assumeTrue = (assumeTrue !== (bool.kind === SyntaxKind.TrueKeyword)) !== (operator !== SyntaxKind.ExclamationEqualsEqualsToken && operator !== SyntaxKind.ExclamationEqualsToken); + return narrowType(type, expr, assumeTrue); + } + + function narrowTypeByBinaryExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type { + switch (expr.operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.BarBarEqualsToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: + case SyntaxKind.QuestionQuestionEqualsToken: + return narrowTypeByTruthiness(narrowType(type, expr.right, assumeTrue), expr.left, assumeTrue); + case SyntaxKind.EqualsEqualsToken: + case SyntaxKind.ExclamationEqualsToken: + case SyntaxKind.EqualsEqualsEqualsToken: + case SyntaxKind.ExclamationEqualsEqualsToken: + const operator = expr.operatorToken.kind; + const left = getReferenceCandidate(expr.left); + const right = getReferenceCandidate(expr.right); + if (left.kind === SyntaxKind.TypeOfExpression && isStringLiteralLike(right)) { + return narrowTypeByTypeof(type, left as TypeOfExpression, operator, right, assumeTrue); + } + if (right.kind === SyntaxKind.TypeOfExpression && isStringLiteralLike(left)) { + return narrowTypeByTypeof(type, right as TypeOfExpression, operator, left, assumeTrue); + } + if (isMatchingReference(reference, left)) { + return narrowTypeByEquality(type, operator, right, assumeTrue); + } + if (isMatchingReference(reference, right)) { + return narrowTypeByEquality(type, operator, left, assumeTrue); + } + if (strictNullChecks) { + if (optionalChainContainsReference(left, reference)) { + type = narrowTypeByOptionalChainContainment(type, operator, right, assumeTrue); + } + else if (optionalChainContainsReference(right, reference)) { + type = narrowTypeByOptionalChainContainment(type, operator, left, assumeTrue); + } + } + const leftAccess = getDiscriminantPropertyAccess(left, type); + if (leftAccess) { + return narrowTypeByDiscriminantProperty(type, leftAccess, operator, right, assumeTrue); + } + const rightAccess = getDiscriminantPropertyAccess(right, type); + if (rightAccess) { + return narrowTypeByDiscriminantProperty(type, rightAccess, operator, left, assumeTrue); + } + if (isMatchingConstructorReference(left)) { + return narrowTypeByConstructor(type, operator, right, assumeTrue); + } + if (isMatchingConstructorReference(right)) { + return narrowTypeByConstructor(type, operator, left, assumeTrue); + } + if (isBooleanLiteral(right) && !isAccessExpression(left)) { + return narrowTypeByBooleanComparison(type, left, right, operator, assumeTrue); + } + if (isBooleanLiteral(left) && !isAccessExpression(right)) { + return narrowTypeByBooleanComparison(type, right, left, operator, assumeTrue); + } + break; + case SyntaxKind.InstanceOfKeyword: + return narrowTypeByInstanceof(type, expr as InstanceofExpression, assumeTrue); + case SyntaxKind.InKeyword: + if (isPrivateIdentifier(expr.left)) { + return narrowTypeByPrivateIdentifierInInExpression(type, expr, assumeTrue); + } + const target = getReferenceCandidate(expr.right); + if (containsMissingType(type) && isAccessExpression(reference) && isMatchingReference(reference.expression, target)) { + const leftType = getTypeOfExpression(expr.left); + if (isTypeUsableAsPropertyName(leftType) && getAccessedPropertyName(reference) === getPropertyNameFromType(leftType)) { + return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined); + } + } + if (isMatchingReference(reference, target)) { + const leftType = getTypeOfExpression(expr.left); + if (isTypeUsableAsPropertyName(leftType)) { + return narrowTypeByInKeyword(type, leftType, assumeTrue); + } + } + break; + case SyntaxKind.CommaToken: + return narrowType(type, expr.right, assumeTrue); + // Ordinarily we won't see && and || expressions in control flow analysis because the Binder breaks those + // expressions down to individual conditional control flows. However, we may encounter them when analyzing + // aliased conditional expressions. + case SyntaxKind.AmpersandAmpersandToken: + return assumeTrue ? + narrowType(narrowType(type, expr.left, /*assumeTrue*/ true), expr.right, /*assumeTrue*/ true) : + getUnionType([narrowType(type, expr.left, /*assumeTrue*/ false), narrowType(type, expr.right, /*assumeTrue*/ false)]); + case SyntaxKind.BarBarToken: + return assumeTrue ? + getUnionType([narrowType(type, expr.left, /*assumeTrue*/ true), narrowType(type, expr.right, /*assumeTrue*/ true)]) : + narrowType(narrowType(type, expr.left, /*assumeTrue*/ false), expr.right, /*assumeTrue*/ false); + } + return type; + } + + function narrowTypeByPrivateIdentifierInInExpression(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type { + const target = getReferenceCandidate(expr.right); + if (!isMatchingReference(reference, target)) { + return type; + } + + Debug.assertNode(expr.left, isPrivateIdentifier); + const symbol = getSymbolForPrivateIdentifierExpression(expr.left); + if (symbol === undefined) { + return type; + } + const classSymbol = symbol.parent!; + const targetType = hasStaticModifier(Debug.checkDefined(symbol.valueDeclaration, "should always have a declaration")) + ? getTypeOfSymbol(classSymbol) as InterfaceType + : getDeclaredTypeOfSymbol(classSymbol); + return getNarrowedType(type, targetType, assumeTrue, /*checkDerived*/ true); + } + + function narrowTypeByOptionalChainContainment(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type { + // We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows: + // When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch. + // When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch. + // When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch. + // When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch. + // When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch. + // When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch. + // When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch. + // When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch. + const equalsOperator = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken; + const nullableFlags = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken ? TypeFlags.Nullable : TypeFlags.Undefined; + const valueType = getTypeOfExpression(value); + // Note that we include any and unknown in the exclusion test because their domain includes null and undefined. + const removeNullable = equalsOperator !== assumeTrue && everyType(valueType, t => !!(t.flags & nullableFlags)) || + equalsOperator === assumeTrue && everyType(valueType, t => !(t.flags & (TypeFlags.AnyOrUnknown | nullableFlags))); + return removeNullable ? getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; + } + + function narrowTypeByEquality(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type { + if (type.flags & TypeFlags.Any) { + return type; + } + if (operator === SyntaxKind.ExclamationEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) { + assumeTrue = !assumeTrue; + } + const valueType = getTypeOfExpression(value); + const doubleEquals = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken; + if (valueType.flags & TypeFlags.Nullable) { + if (!strictNullChecks) { + return type; + } + const facts = doubleEquals ? + assumeTrue ? TypeFacts.EQUndefinedOrNull : TypeFacts.NEUndefinedOrNull : + valueType.flags & TypeFlags.Null ? + assumeTrue ? TypeFacts.EQNull : TypeFacts.NENull : + assumeTrue ? TypeFacts.EQUndefined : TypeFacts.NEUndefined; + return getAdjustedTypeWithFacts(type, facts); + } + if (assumeTrue) { + if (!doubleEquals && (type.flags & TypeFlags.Unknown || someType(type, isEmptyAnonymousObjectType))) { + if (valueType.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive) || isEmptyAnonymousObjectType(valueType)) { + return valueType; + } + if (valueType.flags & TypeFlags.Object) { + return nonPrimitiveType; + } + } + const filteredType = filterType(type, t => areTypesComparable(t, valueType) || doubleEquals && isCoercibleUnderDoubleEquals(t, valueType)); + return replacePrimitivesWithLiterals(filteredType, valueType); + } + if (isUnitType(valueType)) { + return filterType(type, t => !(isUnitLikeType(t) && areTypesComparable(t, valueType))); + } + return type; + } + + function narrowTypeByTypeof(type: Type, typeOfExpr: TypeOfExpression, operator: SyntaxKind, literal: LiteralExpression, assumeTrue: boolean): Type { + // We have '==', '!=', '===', or !==' operator with 'typeof xxx' and string literal operands + if (operator === SyntaxKind.ExclamationEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) { + assumeTrue = !assumeTrue; + } + const target = getReferenceCandidate(typeOfExpr.expression); + if (!isMatchingReference(reference, target)) { + if (strictNullChecks && optionalChainContainsReference(target, reference) && assumeTrue === (literal.text !== "undefined")) { + type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + const propertyAccess = getDiscriminantPropertyAccess(target, type); + if (propertyAccess) { + return narrowTypeByDiscriminant(type, propertyAccess, t => narrowTypeByLiteralExpression(t, literal, assumeTrue)); + } + return type; + } + return narrowTypeByLiteralExpression(type, literal, assumeTrue); + } + + function narrowTypeByLiteralExpression(type: Type, literal: LiteralExpression, assumeTrue: boolean) { + return assumeTrue ? + narrowTypeByTypeName(type, literal.text) : + getAdjustedTypeWithFacts(type, typeofNEFacts.get(literal.text) || TypeFacts.TypeofNEHostObject); + } + + function narrowTypeBySwitchOptionalChainContainment(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData, clauseCheck: (type: Type) => boolean) { + const everyClauseChecks = clauseStart !== clauseEnd && every(getSwitchClauseTypes(switchStatement).slice(clauseStart, clauseEnd), clauseCheck); + return everyClauseChecks ? getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type; + } + + function narrowTypeBySwitchOnDiscriminant(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData) { + // We only narrow if all case expressions specify + // values with unit types, except for the case where + // `type` is unknown. In this instance we map object + // types to the nonPrimitive type and narrow with that. + const switchTypes = getSwitchClauseTypes(switchStatement); + if (!switchTypes.length) { + return type; + } + const clauseTypes = switchTypes.slice(clauseStart, clauseEnd); + const hasDefaultClause = clauseStart === clauseEnd || contains(clauseTypes, neverType); + if ((type.flags & TypeFlags.Unknown) && !hasDefaultClause) { + let groundClauseTypes: Type[] | undefined; + for (let i = 0; i < clauseTypes.length; i += 1) { + const t = clauseTypes[i]; + if (t.flags & (TypeFlags.Primitive | TypeFlags.NonPrimitive)) { + if (groundClauseTypes !== undefined) { + groundClauseTypes.push(t); + } + } + else if (t.flags & TypeFlags.Object) { + if (groundClauseTypes === undefined) { + groundClauseTypes = clauseTypes.slice(0, i); + } + groundClauseTypes.push(nonPrimitiveType); + } + else { + return type; + } + } + return getUnionType(groundClauseTypes === undefined ? clauseTypes : groundClauseTypes); + } + const discriminantType = getUnionType(clauseTypes); + const caseType = discriminantType.flags & TypeFlags.Never ? neverType : + replacePrimitivesWithLiterals(filterType(type, t => areTypesComparable(discriminantType, t)), discriminantType); + if (!hasDefaultClause) { + return caseType; + } + const defaultType = filterType(type, t => !(isUnitLikeType(t) && contains(switchTypes, t.flags & TypeFlags.Undefined ? undefinedType : getRegularTypeOfLiteralType(extractUnitType(t))))); + return caseType.flags & TypeFlags.Never ? defaultType : getUnionType([caseType, defaultType]); + } + + function narrowTypeByTypeName(type: Type, typeName: string) { + switch (typeName) { + case "string": + return narrowTypeByTypeFacts(type, stringType, TypeFacts.TypeofEQString); + case "number": + return narrowTypeByTypeFacts(type, numberType, TypeFacts.TypeofEQNumber); + case "bigint": + return narrowTypeByTypeFacts(type, bigintType, TypeFacts.TypeofEQBigInt); + case "boolean": + return narrowTypeByTypeFacts(type, booleanType, TypeFacts.TypeofEQBoolean); + case "symbol": + return narrowTypeByTypeFacts(type, esSymbolType, TypeFacts.TypeofEQSymbol); + case "object": + return type.flags & TypeFlags.Any ? type : getUnionType([narrowTypeByTypeFacts(type, nonPrimitiveType, TypeFacts.TypeofEQObject), narrowTypeByTypeFacts(type, nullType, TypeFacts.EQNull)]); + case "function": + return type.flags & TypeFlags.Any ? type : narrowTypeByTypeFacts(type, globalFunctionType, TypeFacts.TypeofEQFunction); + case "undefined": + return narrowTypeByTypeFacts(type, undefinedType, TypeFacts.EQUndefined); + } + return narrowTypeByTypeFacts(type, nonPrimitiveType, TypeFacts.TypeofEQHostObject); + } + + function narrowTypeByTypeFacts(type: Type, impliedType: Type, facts: TypeFacts) { + return mapType(type, t => + // We first check if a constituent is a subtype of the implied type. If so, we either keep or eliminate + // the constituent based on its type facts. We use the strict subtype relation because it treats `object` + // as a subtype of `{}`, and we need the type facts check because function types are subtypes of `object`, + // but are classified as "function" according to `typeof`. + isTypeRelatedTo(t, impliedType, strictSubtypeRelation) ? hasTypeFacts(t, facts) ? t : neverType : + // We next check if the consituent is a supertype of the implied type. If so, we substitute the implied + // type. This handles top types like `unknown` and `{}`, and supertypes like `{ toString(): string }`. + isTypeSubtypeOf(impliedType, t) ? impliedType : + // Neither the constituent nor the implied type is a subtype of the other, however their domains may still + // overlap. For example, an unconstrained type parameter and type `string`. If the type facts indicate + // possible overlap, we form an intersection. Otherwise, we eliminate the constituent. + hasTypeFacts(t, facts) ? getIntersectionType([t, impliedType]) : + neverType); + } + + function narrowTypeBySwitchOnTypeOf(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData): Type { + const witnesses = getSwitchClauseTypeOfWitnesses(switchStatement); + if (!witnesses) { + return type; + } + // Equal start and end denotes implicit fallthrough; undefined marks explicit default clause. + const defaultIndex = findIndex(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.DefaultClause); + const hasDefaultClause = clauseStart === clauseEnd || (defaultIndex >= clauseStart && defaultIndex < clauseEnd); + if (hasDefaultClause) { + // In the default clause we filter constituents down to those that are not-equal to all handled cases. + const notEqualFacts = getNotEqualFactsFromTypeofSwitch(clauseStart, clauseEnd, witnesses); + return filterType(type, t => getTypeFacts(t, notEqualFacts) === notEqualFacts); + } + // In the non-default cause we create a union of the type narrowed by each of the listed cases. + const clauseWitnesses = witnesses.slice(clauseStart, clauseEnd); + return getUnionType(map(clauseWitnesses, text => text ? narrowTypeByTypeName(type, text) : neverType)); + } + + function narrowTypeBySwitchOnTrue(type: Type, { switchStatement, clauseStart, clauseEnd }: FlowSwitchClauseData): Type { + const defaultIndex = findIndex(switchStatement.caseBlock.clauses, clause => clause.kind === SyntaxKind.DefaultClause); + const hasDefaultClause = clauseStart === clauseEnd || (defaultIndex >= clauseStart && defaultIndex < clauseEnd); + + // First, narrow away all of the cases that preceded this set of cases. + for (let i = 0; i < clauseStart; i++) { + const clause = switchStatement.caseBlock.clauses[i]; + if (clause.kind === SyntaxKind.CaseClause) { + type = narrowType(type, clause.expression, /*assumeTrue*/ false); + } + } + + // If our current set has a default, then none the other cases were hit either. + // There's no point in narrowing by the the other cases in the set, since we can + // get here through other paths. + if (hasDefaultClause) { + for (let i = clauseEnd; i < switchStatement.caseBlock.clauses.length; i++) { + const clause = switchStatement.caseBlock.clauses[i]; + if (clause.kind === SyntaxKind.CaseClause) { + type = narrowType(type, clause.expression, /*assumeTrue*/ false); + } + } + return type; + } + + // Now, narrow based on the cases in this set. + const clauses = switchStatement.caseBlock.clauses.slice(clauseStart, clauseEnd); + return getUnionType(map(clauses, clause => clause.kind === SyntaxKind.CaseClause ? narrowType(type, clause.expression, /*assumeTrue*/ true) : neverType)); + } + + function isMatchingConstructorReference(expr: Expression) { + return (isPropertyAccessExpression(expr) && idText(expr.name) === "constructor" || + isElementAccessExpression(expr) && isStringLiteralLike(expr.argumentExpression) && expr.argumentExpression.text === "constructor") && + isMatchingReference(reference, expr.expression); + } + + function narrowTypeByConstructor(type: Type, operator: SyntaxKind, identifier: Expression, assumeTrue: boolean): Type { + // Do not narrow when checking inequality. + if (assumeTrue ? (operator !== SyntaxKind.EqualsEqualsToken && operator !== SyntaxKind.EqualsEqualsEqualsToken) : (operator !== SyntaxKind.ExclamationEqualsToken && operator !== SyntaxKind.ExclamationEqualsEqualsToken)) { + return type; + } + + // Get the type of the constructor identifier expression, if it is not a function then do not narrow. + const identifierType = getTypeOfExpression(identifier); + if (!isFunctionType(identifierType) && !isConstructorType(identifierType)) { + return type; + } + + // Get the prototype property of the type identifier so we can find out its type. + const prototypeProperty = getPropertyOfType(identifierType, "prototype" as __String); + if (!prototypeProperty) { + return type; + } + + // Get the type of the prototype, if it is undefined, or the global `Object` or `Function` types then do not narrow. + const prototypeType = getTypeOfSymbol(prototypeProperty); + const candidate = !isTypeAny(prototypeType) ? prototypeType : undefined; + if (!candidate || candidate === globalObjectType || candidate === globalFunctionType) { + return type; + } + + // If the type that is being narrowed is `any` then just return the `candidate` type since every type is a subtype of `any`. + if (isTypeAny(type)) { + return candidate; + } + + // Filter out types that are not considered to be "constructed by" the `candidate` type. + return filterType(type, t => isConstructedBy(t, candidate)); + + function isConstructedBy(source: Type, target: Type) { + // If either the source or target type are a class type then we need to check that they are the same exact type. + // This is because you may have a class `A` that defines some set of properties, and another class `B` + // that defines the same set of properties as class `A`, in that case they are structurally the same + // type, but when you do something like `instanceOfA.constructor === B` it will return false. + if ( + source.flags & TypeFlags.Object && getObjectFlags(source) & ObjectFlags.Class || + target.flags & TypeFlags.Object && getObjectFlags(target) & ObjectFlags.Class + ) { + return source.symbol === target.symbol; + } + + // For all other types just check that the `source` type is a subtype of the `target` type. + return isTypeSubtypeOf(source, target); + } + } + + function narrowTypeByInstanceof(type: Type, expr: InstanceofExpression, assumeTrue: boolean): Type { + const left = getReferenceCandidate(expr.left); + if (!isMatchingReference(reference, left)) { + if (assumeTrue && strictNullChecks && optionalChainContainsReference(left, reference)) { + return getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + return type; + } + const right = expr.right; + const rightType = getTypeOfExpression(right); + if (!isTypeDerivedFrom(rightType, globalObjectType)) { + return type; + } + + // if the right-hand side has an object type with a custom `[Symbol.hasInstance]` method, and that method + // has a type predicate, use the type predicate to perform narrowing. This allows normal `object` types to + // participate in `instanceof`, as per Step 2 of https://tc39.es/ecma262/#sec-instanceofoperator. + const signature = getEffectsSignature(expr); + const predicate = signature && getTypePredicateOfSignature(signature); + if (predicate && predicate.kind === TypePredicateKind.Identifier && predicate.parameterIndex === 0) { + return getNarrowedType(type, predicate.type, assumeTrue, /*checkDerived*/ true); + } + if (!isTypeDerivedFrom(rightType, globalFunctionType)) { + return type; + } + const instanceType = mapType(rightType, getInstanceType); + // Don't narrow from `any` if the target type is exactly `Object` or `Function`, and narrow + // in the false branch only if the target is a non-empty object type. + if ( + isTypeAny(type) && (instanceType === globalObjectType || instanceType === globalFunctionType) || + !assumeTrue && !(instanceType.flags & TypeFlags.Object && !isEmptyAnonymousObjectType(instanceType)) + ) { + return type; + } + return getNarrowedType(type, instanceType, assumeTrue, /*checkDerived*/ true); + } + + function getInstanceType(constructorType: Type) { + const prototypePropertyType = getTypeOfPropertyOfType(constructorType, "prototype" as __String); + if (prototypePropertyType && !isTypeAny(prototypePropertyType)) { + return prototypePropertyType; + } + const constructSignatures = getSignaturesOfType(constructorType, SignatureKind.Construct); + if (constructSignatures.length) { + return getUnionType(map(constructSignatures, signature => getReturnTypeOfSignature(getErasedSignature(signature)))); + } + // We use the empty object type to indicate we don't know the type of objects created by + // this constructor function. + return emptyObjectType; + } + + function getNarrowedType(type: Type, candidate: Type, assumeTrue: boolean, checkDerived: boolean): Type { + const key = type.flags & TypeFlags.Union ? `N${getTypeId(type)},${getTypeId(candidate)},${(assumeTrue ? 1 : 0) | (checkDerived ? 2 : 0)}` : undefined; + return getCachedType(key) ?? setCachedType(key, getNarrowedTypeWorker(type, candidate, assumeTrue, checkDerived)); + } + + function getNarrowedTypeWorker(type: Type, candidate: Type, assumeTrue: boolean, checkDerived: boolean) { + if (!assumeTrue) { + if (type === candidate) { + return neverType; + } + if (checkDerived) { + return filterType(type, t => !isTypeDerivedFrom(t, candidate)); + } + const trueType = getNarrowedType(type, candidate, /*assumeTrue*/ true, /*checkDerived*/ false); + return filterType(type, t => !isTypeSubsetOf(t, trueType)); + } + if (type.flags & TypeFlags.AnyOrUnknown) { + return candidate; + } + if (type === candidate) { + return candidate; + } + + // We first attempt to filter the current type, narrowing constituents as appropriate and removing + // constituents that are unrelated to the candidate. + const isRelated = checkDerived ? isTypeDerivedFrom : isTypeSubtypeOf; + const keyPropertyName = type.flags & TypeFlags.Union ? getKeyPropertyName(type as UnionType) : undefined; + const narrowedType = mapType(candidate, c => { + // If a discriminant property is available, use that to reduce the type. + const discriminant = keyPropertyName && getTypeOfPropertyOfType(c, keyPropertyName); + const matching = discriminant && getConstituentTypeForKeyType(type as UnionType, discriminant); + // For each constituent t in the current type, if t and and c are directly related, pick the most + // specific of the two. When t and c are related in both directions, we prefer c for type predicates + // because that is the asserted type, but t for `instanceof` because generics aren't reflected in + // prototype object types. + const directlyRelated = mapType( + matching || type, + checkDerived ? + t => isTypeDerivedFrom(t, c) ? t : isTypeDerivedFrom(c, t) ? c : neverType : + t => isTypeStrictSubtypeOf(t, c) ? t : isTypeStrictSubtypeOf(c, t) ? c : isTypeSubtypeOf(t, c) ? t : isTypeSubtypeOf(c, t) ? c : neverType, + ); + // If no constituents are directly related, create intersections for any generic constituents that + // are related by constraint. + return directlyRelated.flags & TypeFlags.Never ? + mapType(type, t => maybeTypeOfKind(t, TypeFlags.Instantiable) && isRelated(c, getBaseConstraintOfType(t) || unknownType) ? getIntersectionType([t, c]) : neverType) : + directlyRelated; + }); + // If filtering produced a non-empty type, return that. Otherwise, pick the most specific of the two + // based on assignability, or as a last resort produce an intersection. + return !(narrowedType.flags & TypeFlags.Never) ? narrowedType : + isTypeSubtypeOf(candidate, type) ? candidate : + isTypeAssignableTo(type, candidate) ? type : + isTypeAssignableTo(candidate, type) ? candidate : + getIntersectionType([type, candidate]); + } + + function narrowTypeByCallExpression(type: Type, callExpression: CallExpression, assumeTrue: boolean): Type { + if (hasMatchingArgument(callExpression, reference)) { + const signature = assumeTrue || !isCallChain(callExpression) ? getEffectsSignature(callExpression) : undefined; + const predicate = signature && getTypePredicateOfSignature(signature); + if (predicate && (predicate.kind === TypePredicateKind.This || predicate.kind === TypePredicateKind.Identifier)) { + return narrowTypeByTypePredicate(type, predicate, callExpression, assumeTrue); + } + } + if (containsMissingType(type) && isAccessExpression(reference) && isPropertyAccessExpression(callExpression.expression)) { + const callAccess = callExpression.expression; + if ( + isMatchingReference(reference.expression, getReferenceCandidate(callAccess.expression)) && + isIdentifier(callAccess.name) && callAccess.name.escapedText === "hasOwnProperty" && callExpression.arguments.length === 1 + ) { + const argument = callExpression.arguments[0]; + if (isStringLiteralLike(argument) && getAccessedPropertyName(reference) === escapeLeadingUnderscores(argument.text)) { + return getTypeWithFacts(type, assumeTrue ? TypeFacts.NEUndefined : TypeFacts.EQUndefined); + } + } + } + return type; + } + + function narrowTypeByTypePredicate(type: Type, predicate: TypePredicate, callExpression: CallExpression, assumeTrue: boolean): Type { + // Don't narrow from 'any' if the predicate type is exactly 'Object' or 'Function' + if (predicate.type && !(isTypeAny(type) && (predicate.type === globalObjectType || predicate.type === globalFunctionType))) { + const predicateArgument = getTypePredicateArgument(predicate, callExpression); + if (predicateArgument) { + if (isMatchingReference(reference, predicateArgument)) { + return getNarrowedType(type, predicate.type, assumeTrue, /*checkDerived*/ false); + } + if ( + strictNullChecks && optionalChainContainsReference(predicateArgument, reference) && + ( + assumeTrue && !(hasTypeFacts(predicate.type, TypeFacts.EQUndefined)) || + !assumeTrue && everyType(predicate.type, isNullableType) + ) + ) { + type = getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull); + } + const access = getDiscriminantPropertyAccess(predicateArgument, type); + if (access) { + return narrowTypeByDiscriminant(type, access, t => getNarrowedType(t, predicate.type!, assumeTrue, /*checkDerived*/ false)); + } + } + } + return type; + } + + // Narrow the given type based on the given expression having the assumed boolean value. The returned type + // will be a subtype or the same type as the argument. + function narrowType(type: Type, expr: Expression, assumeTrue: boolean): Type { + // for `a?.b`, we emulate a synthetic `a !== null && a !== undefined` condition for `a` + if ( + isExpressionOfOptionalChainRoot(expr) || + isBinaryExpression(expr.parent) && (expr.parent.operatorToken.kind === SyntaxKind.QuestionQuestionToken || expr.parent.operatorToken.kind === SyntaxKind.QuestionQuestionEqualsToken) && expr.parent.left === expr + ) { + return narrowTypeByOptionality(type, expr, assumeTrue); + } + switch (expr.kind) { + case SyntaxKind.Identifier: + // When narrowing a reference to a const variable, non-assigned parameter, or readonly property, we inline + // up to five levels of aliased conditional expressions that are themselves declared as const variables. + if (!isMatchingReference(reference, expr) && inlineLevel < 5) { + const symbol = getResolvedSymbol(expr as Identifier); + if (isConstantVariable(symbol)) { + const declaration = symbol.valueDeclaration; + if (declaration && isVariableDeclaration(declaration) && !declaration.type && declaration.initializer && isConstantReference(reference)) { + inlineLevel++; + const result = narrowType(type, declaration.initializer, assumeTrue); + inlineLevel--; + return result; + } + } + } + // falls through + case SyntaxKind.ThisKeyword: + case SyntaxKind.SuperKeyword: + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + return narrowTypeByTruthiness(type, expr, assumeTrue); + case SyntaxKind.CallExpression: + return narrowTypeByCallExpression(type, expr as CallExpression, assumeTrue); + case SyntaxKind.ParenthesizedExpression: + case SyntaxKind.NonNullExpression: + return narrowType(type, (expr as ParenthesizedExpression | NonNullExpression).expression, assumeTrue); + case SyntaxKind.BinaryExpression: + return narrowTypeByBinaryExpression(type, expr as BinaryExpression, assumeTrue); + case SyntaxKind.PrefixUnaryExpression: + if ((expr as PrefixUnaryExpression).operator === SyntaxKind.ExclamationToken) { + return narrowType(type, (expr as PrefixUnaryExpression).operand, !assumeTrue); + } + break; + } + return type; + } + + function narrowTypeByOptionality(type: Type, expr: Expression, assumePresent: boolean): Type { + if (isMatchingReference(reference, expr)) { + return getAdjustedTypeWithFacts(type, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull); + } + const access = getDiscriminantPropertyAccess(expr, type); + if (access) { + return narrowTypeByDiscriminant(type, access, t => getTypeWithFacts(t, assumePresent ? TypeFacts.NEUndefinedOrNull : TypeFacts.EQUndefinedOrNull)); + } + return type; + } + } + + function getTypeOfSymbolAtLocation(symbol: Symbol, location: Node) { + symbol = getExportSymbolOfValueSymbolIfExported(symbol); + + // If we have an identifier or a property access at the given location, if the location is + // an dotted name expression, and if the location is not an assignment target, obtain the type + // of the expression (which will reflect control flow analysis). If the expression indeed + // resolved to the given symbol, return the narrowed type. + if (location.kind === SyntaxKind.Identifier || location.kind === SyntaxKind.PrivateIdentifier) { + if (isRightSideOfQualifiedNameOrPropertyAccess(location)) { + location = location.parent; + } + if (isExpressionNode(location) && (!isAssignmentTarget(location) || isWriteAccess(location))) { + const type = removeOptionalTypeMarker( + isWriteAccess(location) && location.kind === SyntaxKind.PropertyAccessExpression ? + checkPropertyAccessExpression(location as PropertyAccessExpression, /*checkMode*/ undefined, /*writeOnly*/ true) : + getTypeOfExpression(location as Expression), + ); + if (getExportSymbolOfValueSymbolIfExported(getNodeLinks(location).resolvedSymbol) === symbol) { + return type; + } + } + } + if (isDeclarationName(location) && isSetAccessor(location.parent) && getAnnotatedAccessorTypeNode(location.parent)) { + return getWriteTypeOfAccessors(location.parent.symbol); + } + // The location isn't a reference to the given symbol, meaning we're being asked + // a hypothetical question of what type the symbol would have if there was a reference + // to it at the given location. Since we have no control flow information for the + // hypothetical reference (control flow information is created and attached by the + // binder), we simply return the declared type of the symbol. + return isRightSideOfAccessExpression(location) && isWriteAccess(location.parent) ? getWriteTypeOfSymbol(symbol) : getNonMissingTypeOfSymbol(symbol); + } + + function getControlFlowContainer(node: Node): Node { + return findAncestor(node.parent, node => + isFunctionLike(node) && !getImmediatelyInvokedFunctionExpression(node) || + node.kind === SyntaxKind.ModuleBlock || + node.kind === SyntaxKind.SourceFile || + node.kind === SyntaxKind.PropertyDeclaration)!; + } + + // Check if a parameter or catch variable is assigned anywhere + function isSymbolAssigned(symbol: Symbol) { + return !isPastLastAssignment(symbol, /*location*/ undefined); + } + + // Return true if there are no assignments to the given symbol or if the given location + // is past the last assignment to the symbol. + function isPastLastAssignment(symbol: Symbol, location: Node | undefined) { + const parent = findAncestor(symbol.valueDeclaration, isFunctionOrSourceFile); + if (!parent) { + return false; + } + const links = getNodeLinks(parent); + if (!(links.flags & NodeCheckFlags.AssignmentsMarked)) { + links.flags |= NodeCheckFlags.AssignmentsMarked; + if (!hasParentWithAssignmentsMarked(parent)) { + markNodeAssignments(parent); + } + } + return !symbol.lastAssignmentPos || location && symbol.lastAssignmentPos < location.pos; + } + + // Check if a parameter or catch variable (or their bindings elements) is assigned anywhere + function isSomeSymbolAssigned(rootDeclaration: Node) { + Debug.assert(isVariableDeclaration(rootDeclaration) || isParameter(rootDeclaration)); + return isSomeSymbolAssignedWorker(rootDeclaration.name); + } + + function isSomeSymbolAssignedWorker(node: BindingName): boolean { + if (node.kind === SyntaxKind.Identifier) { + return isSymbolAssigned(getSymbolOfDeclaration(node.parent as Declaration)); + } + + return some(node.elements, e => e.kind !== SyntaxKind.OmittedExpression && isSomeSymbolAssignedWorker(e.name)); + } + + function hasParentWithAssignmentsMarked(node: Node) { + return !!findAncestor(node.parent, node => isFunctionOrSourceFile(node) && !!(getNodeLinks(node).flags & NodeCheckFlags.AssignmentsMarked)); + } + + function isFunctionOrSourceFile(node: Node) { + return isFunctionLikeDeclaration(node) || isSourceFile(node); + } + + // For all assignments within the given root node, record the last assignment source position for all + // referenced parameters and mutable local variables. When assignments occur in nested functions or + // references occur in export specifiers, record Number.MAX_VALUE as the assignment position. When + // assignments occur in compound statements, record the ending source position of the compound statement + // as the assignment position (this is more conservative than full control flow analysis, but requires + // only a single walk over the AST). + function markNodeAssignments(node: Node) { + switch (node.kind) { + case SyntaxKind.Identifier: + if (isAssignmentTarget(node)) { + const symbol = getResolvedSymbol(node as Identifier); + if (isParameterOrMutableLocalVariable(symbol) && symbol.lastAssignmentPos !== Number.MAX_VALUE) { + const referencingFunction = findAncestor(node, isFunctionOrSourceFile); + const declaringFunction = findAncestor(symbol.valueDeclaration, isFunctionOrSourceFile); + symbol.lastAssignmentPos = referencingFunction === declaringFunction ? extendAssignmentPosition(node, symbol.valueDeclaration!) : Number.MAX_VALUE; + } + } + return; + case SyntaxKind.ExportSpecifier: + const exportDeclaration = (node as ExportSpecifier).parent.parent; + const name = (node as ExportSpecifier).propertyName || (node as ExportSpecifier).name; + if (!(node as ExportSpecifier).isTypeOnly && !exportDeclaration.isTypeOnly && !exportDeclaration.moduleSpecifier && name.kind !== SyntaxKind.StringLiteral) { + const symbol = resolveEntityName(name, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ true); + if (symbol && isParameterOrMutableLocalVariable(symbol)) { + symbol.lastAssignmentPos = Number.MAX_VALUE; + } + } + return; + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + case SyntaxKind.EnumDeclaration: + return; + } + if (isTypeNode(node)) { + return; + } + forEachChild(node, markNodeAssignments); + } + + // Extend the position of the given assignment target node to the end of any intervening variable statement, + // expression statement, compound statement, or class declaration occurring between the node and the given + // declaration node. + function extendAssignmentPosition(node: Node, declaration: Declaration) { + let pos = node.pos; + while (node && node.pos > declaration.pos) { + switch (node.kind) { + case SyntaxKind.VariableStatement: + case SyntaxKind.ExpressionStatement: + case SyntaxKind.IfStatement: + case SyntaxKind.DoStatement: + case SyntaxKind.WhileStatement: + case SyntaxKind.ForStatement: + case SyntaxKind.ForInStatement: + case SyntaxKind.ForOfStatement: + case SyntaxKind.WithStatement: + case SyntaxKind.SwitchStatement: + case SyntaxKind.TryStatement: + case SyntaxKind.ClassDeclaration: + pos = node.end; + } + node = node.parent; + } + return pos; + } + + function isConstantVariable(symbol: Symbol) { + return symbol.flags & SymbolFlags.Variable && (getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Constant) !== 0; + } + + function isParameterOrMutableLocalVariable(symbol: Symbol) { + // Return true if symbol is a parameter, a catch clause variable, or a mutable local variable + const declaration = symbol.valueDeclaration && getRootDeclaration(symbol.valueDeclaration); + return !!declaration && ( + isParameter(declaration) || + isVariableDeclaration(declaration) && (isCatchClause(declaration.parent) || isMutableLocalVariableDeclaration(declaration)) + ); + } + + function isMutableLocalVariableDeclaration(declaration: VariableDeclaration) { + // Return true if symbol is a non-exported and non-global `let` variable + return !!(declaration.parent.flags & NodeFlags.Let) && !( + getCombinedModifierFlags(declaration) & ModifierFlags.Export || + declaration.parent.parent.kind === SyntaxKind.VariableStatement && isGlobalSourceFile(declaration.parent.parent.parent) + ); + } + + function parameterInitializerContainsUndefined(declaration: ParameterDeclaration): boolean { + const links = getNodeLinks(declaration); + + if (links.parameterInitializerContainsUndefined === undefined) { + if (!pushTypeResolution(declaration, TypeSystemPropertyName.ParameterInitializerContainsUndefined)) { + reportCircularityError(declaration.symbol); + return true; + } + + const containsUndefined = !!(hasTypeFacts(checkDeclarationInitializer(declaration, CheckMode.Normal), TypeFacts.IsUndefined)); + + if (!popTypeResolution()) { + reportCircularityError(declaration.symbol); + return true; + } + + links.parameterInitializerContainsUndefined ??= containsUndefined; + } + + return links.parameterInitializerContainsUndefined; + } + + /** remove undefined from the annotated type of a parameter when there is an initializer (that doesn't include undefined) */ + function removeOptionalityFromDeclaredType(declaredType: Type, declaration: VariableLikeDeclaration): Type { + const removeUndefined = strictNullChecks && + declaration.kind === SyntaxKind.Parameter && + declaration.initializer && + hasTypeFacts(declaredType, TypeFacts.IsUndefined) && + !parameterInitializerContainsUndefined(declaration); + + return removeUndefined ? getTypeWithFacts(declaredType, TypeFacts.NEUndefined) : declaredType; + } + + function isConstraintPosition(type: Type, node: Node) { + const parent = node.parent; + // In an element access obj[x], we consider obj to be in a constraint position, except when obj is of + // a generic type without a nullable constraint and x is a generic type. This is because when both obj + // and x are of generic types T and K, we want the resulting type to be T[K]. + return parent.kind === SyntaxKind.PropertyAccessExpression || + parent.kind === SyntaxKind.QualifiedName || + parent.kind === SyntaxKind.CallExpression && (parent as CallExpression).expression === node || + parent.kind === SyntaxKind.NewExpression && (parent as NewExpression).expression === node || + parent.kind === SyntaxKind.ElementAccessExpression && (parent as ElementAccessExpression).expression === node && + !(someType(type, isGenericTypeWithoutNullableConstraint) && isGenericIndexType(getTypeOfExpression((parent as ElementAccessExpression).argumentExpression))); + } + + function isGenericTypeWithUnionConstraint(type: Type): boolean { + return type.flags & TypeFlags.Intersection ? + some((type as IntersectionType).types, isGenericTypeWithUnionConstraint) : + !!(type.flags & TypeFlags.Instantiable && getBaseConstraintOrType(type).flags & (TypeFlags.Nullable | TypeFlags.Union)); + } + + function isGenericTypeWithoutNullableConstraint(type: Type): boolean { + return type.flags & TypeFlags.Intersection ? + some((type as IntersectionType).types, isGenericTypeWithoutNullableConstraint) : + !!(type.flags & TypeFlags.Instantiable && !maybeTypeOfKind(getBaseConstraintOrType(type), TypeFlags.Nullable)); + } + + function hasContextualTypeWithNoGenericTypes(node: Node, checkMode: CheckMode | undefined) { + // Computing the contextual type for a child of a JSX element involves resolving the type of the + // element's tag name, so we exclude that here to avoid circularities. + // If check mode has `CheckMode.RestBindingElement`, we skip binding pattern contextual types, + // as we want the type of a rest element to be generic when possible. + const contextualType = (isIdentifier(node) || isPropertyAccessExpression(node) || isElementAccessExpression(node)) && + !((isJsxOpeningElement(node.parent) || isJsxSelfClosingElement(node.parent)) && node.parent.tagName === node) && + (checkMode && checkMode & CheckMode.RestBindingElement ? + getContextualType(node, ContextFlags.SkipBindingPatterns) + : getContextualType(node, /*contextFlags*/ undefined)); + return contextualType && !isGenericType(contextualType); + } + + function getNarrowableTypeForReference(type: Type, reference: Node, checkMode?: CheckMode) { + if (isNoInferType(type)) { + type = (type as SubstitutionType).baseType; + } + // When the type of a reference is or contains an instantiable type with a union type constraint, and + // when the reference is in a constraint position (where it is known we'll obtain the apparent type) or + // has a contextual type containing no top-level instantiables (meaning constraints will determine + // assignability), we substitute constraints for all instantiables in the type of the reference to give + // control flow analysis an opportunity to narrow it further. For example, for a reference of a type + // parameter type 'T extends string | undefined' with a contextual type 'string', we substitute + // 'string | undefined' to give control flow analysis the opportunity to narrow to type 'string'. + const substituteConstraints = !(checkMode && checkMode & CheckMode.Inferential) && + someType(type, isGenericTypeWithUnionConstraint) && + (isConstraintPosition(type, reference) || hasContextualTypeWithNoGenericTypes(reference, checkMode)); + return substituteConstraints ? mapType(type, getBaseConstraintOrType) : type; + } + + function isExportOrExportExpression(location: Node) { + return !!findAncestor(location, n => { + const parent = n.parent; + if (parent === undefined) { + return "quit"; + } + if (isExportAssignment(parent)) { + return parent.expression === n && isEntityNameExpression(n); + } + if (isExportSpecifier(parent)) { + return parent.name === n || parent.propertyName === n; + } + return false; + }); + } + + /** + * This function marks all the imports the given location refers to as `.referenced` in `NodeLinks` (transitively through local import aliases). + * (This corresponds to not getting elided in JS emit.) + * It can be called on *most* nodes in the AST with `ReferenceHint.Unspecified` and will filter its inputs, but care should be taken to avoid calling it on the RHS of an `import =` or specifiers in a `import {} from "..."`, + * unless you *really* want to *definitely* mark those as referenced. + * These shouldn't be directly marked, and should only get marked transitively by the internals of this function. + * + * @param location The location to mark js import refernces for + * @param hint The kind of reference `location` has already been checked to be + * @param propSymbol The optional symbol of the property we're looking up - this is used for property accesses when `const enum`s do not count as references (no `isolatedModules`, no `preserveConstEnums` + export). It will be calculated if not provided. + * @param parentType The optional type of the parent of the LHS of the property access - this will be recalculated if not provided (but is costly). + */ + function markLinkedReferences(location: PropertyAccessExpression | QualifiedName, hint: ReferenceHint.Property, propSymbol: Symbol | undefined, parentType: Type): void; + function markLinkedReferences(location: Identifier, hint: ReferenceHint.Identifier): void; + function markLinkedReferences(location: ExportAssignment, hint: ReferenceHint.ExportAssignment): void; + function markLinkedReferences(location: JsxOpeningLikeElement | JsxOpeningFragment, hint: ReferenceHint.Jsx): void; + function markLinkedReferences(location: FunctionLikeDeclaration | MethodSignature, hint: ReferenceHint.AsyncFunction): void; + function markLinkedReferences(location: ImportEqualsDeclaration, hint: ReferenceHint.ExportImportEquals): void; + function markLinkedReferences(location: ExportSpecifier, hint: ReferenceHint.ExportSpecifier): void; + function markLinkedReferences(location: HasDecorators, hint: ReferenceHint.Decorator): void; + function markLinkedReferences(location: Node, hint: ReferenceHint.Unspecified, propSymbol?: Symbol, parentType?: Type): void; + function markLinkedReferences(location: Node, hint: ReferenceHint, propSymbol?: Symbol, parentType?: Type) { + if (!canCollectSymbolAliasAccessabilityData) { + return; + } + if (location.flags & NodeFlags.Ambient) { + return; // References within types and declaration files are never going to contribute to retaining a JS import + } + switch (hint) { + case ReferenceHint.Identifier: + return markIdentifierAliasReferenced(location as Identifier); + case ReferenceHint.Property: + return markPropertyAliasReferenced(location as PropertyAccessExpression | QualifiedName, propSymbol, parentType); + case ReferenceHint.ExportAssignment: + return markExportAssignmentAliasReferenced(location as ExportAssignment); + case ReferenceHint.Jsx: + return markJsxAliasReferenced(location as JsxOpeningLikeElement | JsxOpeningFragment); + case ReferenceHint.AsyncFunction: + return markAsyncFunctionAliasReferenced(location as FunctionLikeDeclaration | MethodSignature); + case ReferenceHint.ExportImportEquals: + return markImportEqualsAliasReferenced(location as ImportEqualsDeclaration); + case ReferenceHint.ExportSpecifier: + return markExportSpecifierAliasReferenced(location as ExportSpecifier); + case ReferenceHint.Decorator: + return markDecoratorAliasReferenced(location as HasDecorators); + case ReferenceHint.Unspecified: { + // Identifiers in expression contexts are emitted, so we need to follow their referenced aliases and mark them as used + // Some non-expression identifiers are also treated as expression identifiers for this purpose, eg, `a` in `b = {a}` or `q` in `import r = q` + // This is the exception, rather than the rule - most non-expression identifiers are declaration names. + if (isIdentifier(location) && (isExpressionNode(location) || isShorthandPropertyAssignment(location.parent) || (isImportEqualsDeclaration(location.parent) && location.parent.moduleReference === location)) && shouldMarkIdentifierAliasReferenced(location)) { + if (isPropertyAccessOrQualifiedName(location.parent)) { + const left = isPropertyAccessExpression(location.parent) ? location.parent.expression : location.parent.left; + if (left !== location) return; // Only mark the LHS (the RHS is a property lookup) + } + markIdentifierAliasReferenced(location); + return; + } + if (isPropertyAccessOrQualifiedName(location)) { + let topProp: Node | undefined = location; + while (isPropertyAccessOrQualifiedName(topProp)) { + if (isPartOfTypeNode(topProp)) return; + topProp = topProp.parent; + } + return markPropertyAliasReferenced(location); + } + if (isExportAssignment(location)) { + return markExportAssignmentAliasReferenced(location); + } + if (isJsxOpeningLikeElement(location) || isJsxOpeningFragment(location)) { + return markJsxAliasReferenced(location); + } + if (isImportEqualsDeclaration(location)) { + if (isInternalModuleImportEqualsDeclaration(location) || checkExternalImportOrExportDeclaration(location)) { + return markImportEqualsAliasReferenced(location); + } + return; + } + if (isExportSpecifier(location)) { + return markExportSpecifierAliasReferenced(location); + } + if (isFunctionLikeDeclaration(location) || isMethodSignature(location)) { + markAsyncFunctionAliasReferenced(location); + // Might be decorated, fall through to decorator final case + } + if (!compilerOptions.emitDecoratorMetadata) { + return; + } + if (!canHaveDecorators(location) || !hasDecorators(location) || !location.modifiers || !nodeCanBeDecorated(legacyDecorators, location, location.parent, location.parent.parent)) { + return; + } + + return markDecoratorAliasReferenced(location); + } + default: + Debug.assertNever(hint, `Unhandled reference hint: ${hint}`); + } + } + + function markIdentifierAliasReferenced(location: Identifier) { + const symbol = getResolvedSymbol(location); + if (symbol && symbol !== argumentsSymbol && symbol !== unknownSymbol && !isThisInTypeQuery(location)) { + markAliasReferenced(symbol, location); + } + } + + function markPropertyAliasReferenced(location: PropertyAccessExpression | QualifiedName, propSymbol?: Symbol, parentType?: Type) { + const left = isPropertyAccessExpression(location) ? location.expression : location.left; + if (isThisIdentifier(left) || !isIdentifier(left)) { + return; + } + const parentSymbol = getResolvedSymbol(left); + if (!parentSymbol || parentSymbol === unknownSymbol) { + return; + } + // In `Foo.Bar.Baz`, 'Foo' is not referenced if 'Bar' is a const enum or a module containing only const enums. + // `Foo` is also not referenced in `enum FooCopy { Bar = Foo.Bar }`, because the enum member value gets inlined + // here even if `Foo` is not a const enum. + // + // The exceptions are: + // 1. if 'isolatedModules' is enabled, because the const enum value will not be inlined, and + // 2. if 'preserveConstEnums' is enabled and the expression is itself an export, e.g. `export = Foo.Bar.Baz`. + // + // The property lookup is deferred as much as possible, in as many situations as possible, to avoid alias marking + // pulling on types/symbols it doesn't strictly need to. + if (getIsolatedModules(compilerOptions) || (shouldPreserveConstEnums(compilerOptions) && isExportOrExportExpression(location))) { + markAliasReferenced(parentSymbol, location); + return; + } + // Hereafter, this relies on type checking - but every check prior to this only used symbol information + const leftType = parentType || checkExpressionCached(left); + if (isTypeAny(leftType) || leftType === silentNeverType) { + markAliasReferenced(parentSymbol, location); + return; + } + let prop = propSymbol; + if (!prop && !parentType) { + const right = isPropertyAccessExpression(location) ? location.name : location.right; + const lexicallyScopedSymbol = isPrivateIdentifier(right) && lookupSymbolForPrivateIdentifierDeclaration(right.escapedText, right); + const assignmentKind = getAssignmentTargetKind(location); + const apparentType = getApparentType(assignmentKind !== AssignmentKind.None || isMethodAccessForCall(location) ? getWidenedType(leftType) : leftType); + prop = isPrivateIdentifier(right) ? lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(apparentType, lexicallyScopedSymbol) || undefined : getPropertyOfType(apparentType, right.escapedText); + } + if ( + !(prop && (isConstEnumOrConstEnumOnlyModule(prop) || prop.flags & SymbolFlags.EnumMember && location.parent.kind === SyntaxKind.EnumMember)) + ) { + markAliasReferenced(parentSymbol, location); + } + return; + } + + function markExportAssignmentAliasReferenced(location: ExportAssignment) { + if (isIdentifier(location.expression)) { + const id = location.expression; + const sym = getExportSymbolOfValueSymbolIfExported(resolveEntityName(id, SymbolFlags.All, /*ignoreErrors*/ true, /*dontResolveAlias*/ true, location)); + if (sym) { + markAliasReferenced(sym, id); + } + } + } + + function markJsxAliasReferenced(node: JsxOpeningLikeElement | JsxOpeningFragment) { + if (!getJsxNamespaceContainerForImplicitImport(node)) { + // The reactNamespace/jsxFactory's root symbol should be marked as 'used' so we don't incorrectly elide its import. + // And if there is no reactNamespace/jsxFactory's symbol in scope when targeting React emit, we should issue an error. + const jsxFactoryRefErr = diagnostics && compilerOptions.jsx === JsxEmit.React ? Diagnostics.Cannot_find_name_0 : undefined; + const jsxFactoryNamespace = getJsxNamespace(node); + const jsxFactoryLocation = isJsxOpeningLikeElement(node) ? node.tagName : node; + + // allow null as jsxFragmentFactory + let jsxFactorySym: Symbol | undefined; + if (!(isJsxOpeningFragment(node) && jsxFactoryNamespace === "null")) { + jsxFactorySym = resolveName(jsxFactoryLocation, jsxFactoryNamespace, SymbolFlags.Value, jsxFactoryRefErr, /*isUse*/ true); + } + + if (jsxFactorySym) { + // Mark local symbol as referenced here because it might not have been marked + // if jsx emit was not jsxFactory as there wont be error being emitted + jsxFactorySym.isReferenced = SymbolFlags.All; + + // If react/jsxFactory symbol is alias, mark it as refereced + if (canCollectSymbolAliasAccessabilityData && jsxFactorySym.flags & SymbolFlags.Alias && !getTypeOnlyAliasDeclaration(jsxFactorySym)) { + markAliasSymbolAsReferenced(jsxFactorySym); + } + } + + // For JsxFragment, mark jsx pragma as referenced via resolveName + if (isJsxOpeningFragment(node)) { + const file = getSourceFileOfNode(node); + const localJsxNamespace = getLocalJsxNamespace(file); + if (localJsxNamespace) { + resolveName(jsxFactoryLocation, localJsxNamespace, SymbolFlags.Value, jsxFactoryRefErr, /*isUse*/ true); + } + } + } + return; + } + + function markAsyncFunctionAliasReferenced(location: FunctionLikeDeclaration | MethodSignature) { + if (languageVersion < ScriptTarget.ES2015) { + if (getFunctionFlags(location) & FunctionFlags.Async) { + const returnTypeNode = getEffectiveReturnTypeNode(location); + markTypeNodeAsReferenced(returnTypeNode); + } + } + } + + function markImportEqualsAliasReferenced(location: ImportEqualsDeclaration) { + if (hasSyntacticModifier(location, ModifierFlags.Export)) { + markExportAsReferenced(location); + } + } + + function markExportSpecifierAliasReferenced(location: ExportSpecifier) { + if (!location.parent.parent.moduleSpecifier && !location.isTypeOnly && !location.parent.parent.isTypeOnly) { + const exportedName = location.propertyName || location.name; + if (exportedName.kind === SyntaxKind.StringLiteral) { + return; // Skip for invalid syntax like this: export { "x" } + } + const symbol = resolveName(exportedName, exportedName.escapedText, SymbolFlags.Value | SymbolFlags.Type | SymbolFlags.Namespace | SymbolFlags.Alias, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (symbol && (symbol === undefinedSymbol || symbol === globalThisSymbol || symbol.declarations && isGlobalSourceFile(getDeclarationContainer(symbol.declarations[0])))) { + // Do nothing, non-local symbol + } + else { + const target = symbol && (symbol.flags & SymbolFlags.Alias ? resolveAlias(symbol) : symbol); + if (!target || getSymbolFlags(target) & SymbolFlags.Value) { + markExportAsReferenced(location); // marks export as used + markIdentifierAliasReferenced(exportedName); // marks target of export as used + } + } + return; + } + } + + function markDecoratorAliasReferenced(node: HasDecorators) { + if (compilerOptions.emitDecoratorMetadata) { + const firstDecorator = find(node.modifiers, isDecorator); + if (!firstDecorator) { + return; + } + + checkExternalEmitHelpers(firstDecorator, ExternalEmitHelpers.Metadata); + + // we only need to perform these checks if we are emitting serialized type metadata for the target of a decorator. + switch (node.kind) { + case SyntaxKind.ClassDeclaration: + const constructor = getFirstConstructorWithBody(node); + if (constructor) { + for (const parameter of constructor.parameters) { + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); + } + } + break; + + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + const otherKind = node.kind === SyntaxKind.GetAccessor ? SyntaxKind.SetAccessor : SyntaxKind.GetAccessor; + const otherAccessor = getDeclarationOfKind(getSymbolOfDeclaration(node), otherKind); + markDecoratorMedataDataTypeNodeAsReferenced(getAnnotatedAccessorTypeNode(node) || otherAccessor && getAnnotatedAccessorTypeNode(otherAccessor)); + break; + case SyntaxKind.MethodDeclaration: + for (const parameter of node.parameters) { + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); + } + + markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveReturnTypeNode(node)); + break; + + case SyntaxKind.PropertyDeclaration: + markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveTypeAnnotationNode(node)); + break; + + case SyntaxKind.Parameter: + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(node)); + const containingSignature = node.parent; + for (const parameter of containingSignature.parameters) { + markDecoratorMedataDataTypeNodeAsReferenced(getParameterTypeNodeForDecoratorCheck(parameter)); + } + markDecoratorMedataDataTypeNodeAsReferenced(getEffectiveReturnTypeNode(containingSignature)); + break; + } + } + } + + function markAliasReferenced(symbol: Symbol, location: Node) { + if (!canCollectSymbolAliasAccessabilityData) { + return; + } + if (isNonLocalAlias(symbol, /*excludes*/ SymbolFlags.Value) && !isInTypeQuery(location)) { + const target = resolveAlias(symbol); + if (getSymbolFlags(symbol, /*excludeTypeOnlyMeanings*/ true) & (SymbolFlags.Value | SymbolFlags.ExportValue)) { + // An alias resolving to a const enum cannot be elided if (1) 'isolatedModules' is enabled + // (because the const enum value will not be inlined), or if (2) the alias is an export + // of a const enum declaration that will be preserved. + if ( + getIsolatedModules(compilerOptions) || + shouldPreserveConstEnums(compilerOptions) && isExportOrExportExpression(location) || + !isConstEnumOrConstEnumOnlyModule(getExportSymbolOfValueSymbolIfExported(target)) + ) { + markAliasSymbolAsReferenced(symbol); + } + } + } + } + + // When an alias symbol is referenced, we need to mark the entity it references as referenced and in turn repeat that until + // we reach a non-alias or an exported entity (which is always considered referenced). We do this by checking the target of + // the alias as an expression (which recursively takes us back here if the target references another alias). + function markAliasSymbolAsReferenced(symbol: Symbol) { + Debug.assert(canCollectSymbolAliasAccessabilityData); + const links = getSymbolLinks(symbol); + if (!links.referenced) { + links.referenced = true; + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + // We defer checking of the reference of an `import =` until the import itself is referenced, + // This way a chain of imports can be elided if ultimately the final input is only used in a type + // position. + if (isInternalModuleImportEqualsDeclaration(node)) { + if (getSymbolFlags(resolveSymbol(symbol)) & SymbolFlags.Value) { + // import foo = + const left = getFirstIdentifier(node.moduleReference as EntityNameExpression); + markIdentifierAliasReferenced(left); + } + } + } + } + + function markExportAsReferenced(node: ImportEqualsDeclaration | ExportSpecifier) { + const symbol = getSymbolOfDeclaration(node); + const target = resolveAlias(symbol); + if (target) { + const markAlias = target === unknownSymbol || + ((getSymbolFlags(symbol, /*excludeTypeOnlyMeanings*/ true) & SymbolFlags.Value) && !isConstEnumOrConstEnumOnlyModule(target)); + + if (markAlias) { + markAliasSymbolAsReferenced(symbol); + } + } + } + + function markEntityNameOrEntityExpressionAsReference(typeName: EntityNameOrEntityNameExpression | undefined, forDecoratorMetadata: boolean) { + if (!typeName) return; + + const rootName = getFirstIdentifier(typeName); + const meaning = (typeName.kind === SyntaxKind.Identifier ? SymbolFlags.Type : SymbolFlags.Namespace) | SymbolFlags.Alias; + const rootSymbol = resolveName(rootName, rootName.escapedText, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (rootSymbol && rootSymbol.flags & SymbolFlags.Alias) { + if ( + canCollectSymbolAliasAccessabilityData + && symbolIsValue(rootSymbol) + && !isConstEnumOrConstEnumOnlyModule(resolveAlias(rootSymbol)) + && !getTypeOnlyAliasDeclaration(rootSymbol) + ) { + markAliasSymbolAsReferenced(rootSymbol); + } + else if ( + forDecoratorMetadata + && getIsolatedModules(compilerOptions) + && getEmitModuleKind(compilerOptions) >= ModuleKind.ES2015 + && !symbolIsValue(rootSymbol) + && !some(rootSymbol.declarations, isTypeOnlyImportOrExportDeclaration) + ) { + const diag = error(typeName, Diagnostics.A_type_referenced_in_a_decorated_signature_must_be_imported_with_import_type_or_a_namespace_import_when_isolatedModules_and_emitDecoratorMetadata_are_enabled); + const aliasDeclaration = find(rootSymbol.declarations || emptyArray, isAliasSymbolDeclaration); + if (aliasDeclaration) { + addRelatedInfo(diag, createDiagnosticForNode(aliasDeclaration, Diagnostics._0_was_imported_here, idText(rootName))); + } + } + } + } + + /** + * If a TypeNode can be resolved to a value symbol imported from an external module, it is + * marked as referenced to prevent import elision. + */ + function markTypeNodeAsReferenced(node: TypeNode | undefined) { + markEntityNameOrEntityExpressionAsReference(node && getEntityNameFromTypeNode(node), /*forDecoratorMetadata*/ false); + } + + /** + * This function marks the type used for metadata decorator as referenced if it is import + * from external module. + * This is different from markTypeNodeAsReferenced because it tries to simplify type nodes in + * union and intersection type + * @param node + */ + function markDecoratorMedataDataTypeNodeAsReferenced(node: TypeNode | undefined): void { + const entityName = getEntityNameForDecoratorMetadata(node); + if (entityName && isEntityName(entityName)) { + markEntityNameOrEntityExpressionAsReference(entityName, /*forDecoratorMetadata*/ true); + } + } + + function getNarrowedTypeOfSymbol(symbol: Symbol, location: Identifier, checkMode?: CheckMode) { + const type = getTypeOfSymbol(symbol, checkMode); + const declaration = symbol.valueDeclaration; + if (declaration) { + // If we have a non-rest binding element with no initializer declared as a const variable or a const-like + // parameter (a parameter for which there are no assignments in the function body), and if the parent type + // for the destructuring is a union type, one or more of the binding elements may represent discriminant + // properties, and we want the effects of conditional checks on such discriminants to affect the types of + // other binding elements from the same destructuring. Consider: + // + // type Action = + // | { kind: 'A', payload: number } + // | { kind: 'B', payload: string }; + // + // function f({ kind, payload }: Action) { + // if (kind === 'A') { + // payload.toFixed(); + // } + // if (kind === 'B') { + // payload.toUpperCase(); + // } + // } + // + // Above, we want the conditional checks on 'kind' to affect the type of 'payload'. To facilitate this, we use + // the binding pattern AST instance for '{ kind, payload }' as a pseudo-reference and narrow this reference + // as if it occurred in the specified location. We then recompute the narrowed binding element type by + // destructuring from the narrowed parent type. + if (isBindingElement(declaration) && !declaration.initializer && !declaration.dotDotDotToken && declaration.parent.elements.length >= 2) { + const parent = declaration.parent.parent; + const rootDeclaration = getRootDeclaration(parent); + if (rootDeclaration.kind === SyntaxKind.VariableDeclaration && getCombinedNodeFlagsCached(rootDeclaration) & NodeFlags.Constant || rootDeclaration.kind === SyntaxKind.Parameter) { + const links = getNodeLinks(parent); + if (!(links.flags & NodeCheckFlags.InCheckIdentifier)) { + links.flags |= NodeCheckFlags.InCheckIdentifier; + const parentType = getTypeForBindingElementParent(parent, CheckMode.Normal); + const parentTypeConstraint = parentType && mapType(parentType, getBaseConstraintOrType); + links.flags &= ~NodeCheckFlags.InCheckIdentifier; + if (parentTypeConstraint && parentTypeConstraint.flags & TypeFlags.Union && !(rootDeclaration.kind === SyntaxKind.Parameter && isSomeSymbolAssigned(rootDeclaration))) { + const pattern = declaration.parent; + const narrowedType = getFlowTypeOfReference(pattern, parentTypeConstraint, parentTypeConstraint, /*flowContainer*/ undefined, location.flowNode); + if (narrowedType.flags & TypeFlags.Never) { + return neverType; + } + // Destructurings are validated against the parent type elsewhere. Here we disable tuple bounds + // checks because the narrowed type may have lower arity than the full parent type. For example, + // for the declaration [x, y]: [1, 2] | [3], we may have narrowed the parent type to just [3]. + return getBindingElementTypeFromParentType(declaration, narrowedType, /*noTupleBoundsCheck*/ true); + } + } + } + } + // If we have a const-like parameter with no type annotation or initializer, and if the parameter is contextually + // typed by a signature with a single rest parameter of a union of tuple types, one or more of the parameters may + // represent discriminant tuple elements, and we want the effects of conditional checks on such discriminants to + // affect the types of other parameters in the same parameter list. Consider: + // + // type Action = [kind: 'A', payload: number] | [kind: 'B', payload: string]; + // + // const f: (...args: Action) => void = (kind, payload) => { + // if (kind === 'A') { + // payload.toFixed(); + // } + // if (kind === 'B') { + // payload.toUpperCase(); + // } + // } + // + // Above, we want the conditional checks on 'kind' to affect the type of 'payload'. To facilitate this, we use + // the arrow function AST node for '(kind, payload) => ...' as a pseudo-reference and narrow this reference as + // if it occurred in the specified location. We then recompute the narrowed parameter type by indexing into the + // narrowed tuple type. + if (isParameter(declaration) && !declaration.type && !declaration.initializer && !declaration.dotDotDotToken) { + const func = declaration.parent; + if (func.parameters.length >= 2 && isContextSensitiveFunctionOrObjectLiteralMethod(func)) { + const contextualSignature = getContextualSignature(func); + if (contextualSignature && contextualSignature.parameters.length === 1 && signatureHasRestParameter(contextualSignature)) { + const restType = getReducedApparentType(instantiateType(getTypeOfSymbol(contextualSignature.parameters[0]), getInferenceContext(func)?.nonFixingMapper)); + if (restType.flags & TypeFlags.Union && everyType(restType, isTupleType) && !some(func.parameters, isSomeSymbolAssigned)) { + const narrowedType = getFlowTypeOfReference(func, restType, restType, /*flowContainer*/ undefined, location.flowNode); + const index = func.parameters.indexOf(declaration) - (getThisParameter(func) ? 1 : 0); + return getIndexedAccessType(narrowedType, getNumberLiteralType(index)); + } + } + } + } + } + return type; + } + + /** + * This part of `checkIdentifier` is kept seperate from the rest, so `NodeCheckFlags` (and related diagnostics) can be lazily calculated + * without calculating the flow type of the identifier. + */ + function checkIdentifierCalculateNodeCheckFlags(node: Identifier, symbol: Symbol) { + if (isThisInTypeQuery(node)) return; + + // As noted in ECMAScript 6 language spec, arrow functions never have an arguments objects. + // Although in down-level emit of arrow function, we emit it using function expression which means that + // arguments objects will be bound to the inner object; emitting arrow function natively in ES6, arguments objects + // will be bound to non-arrow function that contain this arrow function. This results in inconsistent behavior. + // To avoid that we will give an error to users if they use arguments objects in arrow function so that they + // can explicitly bound arguments objects + if (symbol === argumentsSymbol) { + if (isInPropertyInitializerOrClassStaticBlock(node)) { + error(node, Diagnostics.arguments_cannot_be_referenced_in_property_initializers); + return; + } + + let container = getContainingFunction(node); + if (container) { + if (languageVersion < ScriptTarget.ES2015) { + if (container.kind === SyntaxKind.ArrowFunction) { + error(node, Diagnostics.The_arguments_object_cannot_be_referenced_in_an_arrow_function_in_ES5_Consider_using_a_standard_function_expression); + } + else if (hasSyntacticModifier(container, ModifierFlags.Async)) { + error(node, Diagnostics.The_arguments_object_cannot_be_referenced_in_an_async_function_or_method_in_ES5_Consider_using_a_standard_function_or_method); + } + } + + getNodeLinks(container).flags |= NodeCheckFlags.CaptureArguments; + while (container && isArrowFunction(container)) { + container = getContainingFunction(container); + if (container) { + getNodeLinks(container).flags |= NodeCheckFlags.CaptureArguments; + } + } + } + return; + } + + const localOrExportSymbol = getExportSymbolOfValueSymbolIfExported(symbol); + const targetSymbol = resolveAliasWithDeprecationCheck(localOrExportSymbol, node); + if (isDeprecatedSymbol(targetSymbol) && isUncalledFunctionReference(node, targetSymbol) && targetSymbol.declarations) { + addDeprecatedSuggestion(node, targetSymbol.declarations, node.escapedText as string); + } + + const declaration = localOrExportSymbol.valueDeclaration; + if (declaration && localOrExportSymbol.flags & SymbolFlags.Class) { + // When we downlevel classes we may emit some code outside of the class body. Due to the fact the + // class name is double-bound, we must ensure we mark references to the class name so that we can + // emit an alias to the class later. + if (isClassLike(declaration) && declaration.name !== node) { + let container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + while (container.kind !== SyntaxKind.SourceFile && container.parent !== declaration) { + container = getThisContainer(container, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + } + + if (container.kind !== SyntaxKind.SourceFile) { + getNodeLinks(declaration).flags |= NodeCheckFlags.ContainsConstructorReference; + getNodeLinks(container).flags |= NodeCheckFlags.ContainsConstructorReference; + getNodeLinks(node).flags |= NodeCheckFlags.ConstructorReference; + } + } + } + + checkNestedBlockScopedBinding(node, symbol); + } + + function checkIdentifier(node: Identifier, checkMode: CheckMode | undefined): Type { + if (isThisInTypeQuery(node)) { + return checkThisExpression(node); + } + + const symbol = getResolvedSymbol(node); + if (symbol === unknownSymbol) { + return errorType; + } + + checkIdentifierCalculateNodeCheckFlags(node, symbol); + + if (symbol === argumentsSymbol) { + if (isInPropertyInitializerOrClassStaticBlock(node)) { + return errorType; + } + return getTypeOfSymbol(symbol); + } + + if (shouldMarkIdentifierAliasReferenced(node)) { + markLinkedReferences(node, ReferenceHint.Identifier); + } + + const localOrExportSymbol = getExportSymbolOfValueSymbolIfExported(symbol); + let declaration = localOrExportSymbol.valueDeclaration; + + let type = getNarrowedTypeOfSymbol(localOrExportSymbol, node, checkMode); + const assignmentKind = getAssignmentTargetKind(node); + + if (assignmentKind) { + if ( + !(localOrExportSymbol.flags & SymbolFlags.Variable) && + !(isInJSFile(node) && localOrExportSymbol.flags & SymbolFlags.ValueModule) + ) { + const assignmentError = localOrExportSymbol.flags & SymbolFlags.Enum ? Diagnostics.Cannot_assign_to_0_because_it_is_an_enum + : localOrExportSymbol.flags & SymbolFlags.Class ? Diagnostics.Cannot_assign_to_0_because_it_is_a_class + : localOrExportSymbol.flags & SymbolFlags.Module ? Diagnostics.Cannot_assign_to_0_because_it_is_a_namespace + : localOrExportSymbol.flags & SymbolFlags.Function ? Diagnostics.Cannot_assign_to_0_because_it_is_a_function + : localOrExportSymbol.flags & SymbolFlags.Alias ? Diagnostics.Cannot_assign_to_0_because_it_is_an_import + : Diagnostics.Cannot_assign_to_0_because_it_is_not_a_variable; + + error(node, assignmentError, symbolToString(symbol)); + return errorType; + } + if (isReadonlySymbol(localOrExportSymbol)) { + if (localOrExportSymbol.flags & SymbolFlags.Variable) { + error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant, symbolToString(symbol)); + } + else { + error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(symbol)); + } + return errorType; + } + } + + const isAlias = localOrExportSymbol.flags & SymbolFlags.Alias; + + // We only narrow variables and parameters occurring in a non-assignment position. For all other + // entities we simply return the declared type. + if (localOrExportSymbol.flags & SymbolFlags.Variable) { + if (assignmentKind === AssignmentKind.Definite) { + return isInCompoundLikeAssignment(node) ? getBaseTypeOfLiteralType(type) : type; + } + } + else if (isAlias) { + declaration = getDeclarationOfAliasSymbol(symbol); + } + else { + return type; + } + + if (!declaration) { + return type; + } + + type = getNarrowableTypeForReference(type, node, checkMode); + + // The declaration container is the innermost function that encloses the declaration of the variable + // or parameter. The flow container is the innermost function starting with which we analyze the control + // flow graph to determine the control flow based type. + const isParameter = getRootDeclaration(declaration).kind === SyntaxKind.Parameter; + const declarationContainer = getControlFlowContainer(declaration); + let flowContainer = getControlFlowContainer(node); + const isOuterVariable = flowContainer !== declarationContainer; + const isSpreadDestructuringAssignmentTarget = node.parent && node.parent.parent && isSpreadAssignment(node.parent) && isDestructuringAssignmentTarget(node.parent.parent); + const isModuleExports = symbol.flags & SymbolFlags.ModuleExports; + const typeIsAutomatic = type === autoType || type === autoArrayType; + const isAutomaticTypeInNonNull = typeIsAutomatic && node.parent.kind === SyntaxKind.NonNullExpression; + // When the control flow originates in a function expression, arrow function, method, or accessor, and + // we are referencing a closed-over const variable or parameter or mutable local variable past its last + // assignment, we extend the origin of the control flow analysis to include the immediately enclosing + // control flow container. + while ( + flowContainer !== declarationContainer && ( + flowContainer.kind === SyntaxKind.FunctionExpression || + flowContainer.kind === SyntaxKind.ArrowFunction || + isObjectLiteralOrClassExpressionMethodOrAccessor(flowContainer) + ) && ( + isConstantVariable(localOrExportSymbol) && type !== autoArrayType || + isParameterOrMutableLocalVariable(localOrExportSymbol) && isPastLastAssignment(localOrExportSymbol, node) + ) + ) { + flowContainer = getControlFlowContainer(flowContainer); + } + // We only look for uninitialized variables in strict null checking mode, and only when we can analyze + // the entire control flow graph from the variable's declaration (i.e. when the flow container and + // declaration container are the same). + const assumeInitialized = isParameter || isAlias || isOuterVariable || isSpreadDestructuringAssignmentTarget || isModuleExports || isSameScopedBindingElement(node, declaration) || + type !== autoType && type !== autoArrayType && (!strictNullChecks || (type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void)) !== 0 || + isInTypeQuery(node) || isInAmbientOrTypeNode(node) || node.parent.kind === SyntaxKind.ExportSpecifier) || + node.parent.kind === SyntaxKind.NonNullExpression || + declaration.kind === SyntaxKind.VariableDeclaration && (declaration as VariableDeclaration).exclamationToken || + declaration.flags & NodeFlags.Ambient; + const initialType = isAutomaticTypeInNonNull ? undefinedType : + assumeInitialized ? (isParameter ? removeOptionalityFromDeclaredType(type, declaration as VariableLikeDeclaration) : type) : + typeIsAutomatic ? undefinedType : getOptionalType(type); + const flowType = isAutomaticTypeInNonNull ? getNonNullableType(getFlowTypeOfReference(node, type, initialType, flowContainer)) : + getFlowTypeOfReference(node, type, initialType, flowContainer); + // A variable is considered uninitialized when it is possible to analyze the entire control flow graph + // from declaration to use, and when the variable's declared type doesn't include undefined but the + // control flow based type does include undefined. + if (!isEvolvingArrayOperationTarget(node) && (type === autoType || type === autoArrayType)) { + if (flowType === autoType || flowType === autoArrayType) { + if (noImplicitAny) { + error(getNameOfDeclaration(declaration), Diagnostics.Variable_0_implicitly_has_type_1_in_some_locations_where_its_type_cannot_be_determined, symbolToString(symbol), typeToString(flowType)); + error(node, Diagnostics.Variable_0_implicitly_has_an_1_type, symbolToString(symbol), typeToString(flowType)); + } + return convertAutoToAny(flowType); + } + } + else if (!assumeInitialized && !containsUndefinedType(type) && containsUndefinedType(flowType)) { + error(node, Diagnostics.Variable_0_is_used_before_being_assigned, symbolToString(symbol)); + // Return the declared type to reduce follow-on errors + return type; + } + return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType; + } + + function isSameScopedBindingElement(node: Identifier, declaration: Declaration) { + if (isBindingElement(declaration)) { + const bindingElement = findAncestor(node, isBindingElement); + return bindingElement && getRootDeclaration(bindingElement) === getRootDeclaration(declaration); + } + } + + function shouldMarkIdentifierAliasReferenced(node: Identifier): boolean { + const parent = node.parent; + if (parent) { + // A property access expression LHS? checkPropertyAccessExpression will handle that. + if (isPropertyAccessExpression(parent) && parent.expression === node) { + return false; + } + // Next two check for an identifier inside a type only export. + if (isExportSpecifier(parent) && parent.isTypeOnly) { + return false; + } + const greatGrandparent = parent.parent?.parent; + if (greatGrandparent && isExportDeclaration(greatGrandparent) && greatGrandparent.isTypeOnly) { + return false; + } + } + return true; + } + + function isInsideFunctionOrInstancePropertyInitializer(node: Node, threshold: Node): boolean { + return !!findAncestor(node, n => + n === threshold ? "quit" : isFunctionLike(n) || ( + n.parent && isPropertyDeclaration(n.parent) && !hasStaticModifier(n.parent) && n.parent.initializer === n + )); + } + + function getPartOfForStatementContainingNode(node: Node, container: ForStatement) { + return findAncestor(node, n => n === container ? "quit" : n === container.initializer || n === container.condition || n === container.incrementor || n === container.statement); + } + + function getEnclosingIterationStatement(node: Node): Node | undefined { + return findAncestor(node, n => (!n || nodeStartsNewLexicalEnvironment(n)) ? "quit" : isIterationStatement(n, /*lookInLabeledStatements*/ false)); + } + + function checkNestedBlockScopedBinding(node: Identifier, symbol: Symbol): void { + if ( + languageVersion >= ScriptTarget.ES2015 || + (symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.Class)) === 0 || + !symbol.valueDeclaration || + isSourceFile(symbol.valueDeclaration) || + symbol.valueDeclaration.parent.kind === SyntaxKind.CatchClause + ) { + return; + } + + // 1. walk from the use site up to the declaration and check + // if there is anything function like between declaration and use-site (is binding/class is captured in function). + // 2. walk from the declaration up to the boundary of lexical environment and check + // if there is an iteration statement in between declaration and boundary (is binding/class declared inside iteration statement) + + const container = getEnclosingBlockScopeContainer(symbol.valueDeclaration); + const isCaptured = isInsideFunctionOrInstancePropertyInitializer(node, container); + + const enclosingIterationStatement = getEnclosingIterationStatement(container); + if (enclosingIterationStatement) { + if (isCaptured) { + // mark iteration statement as containing block-scoped binding captured in some function + let capturesBlockScopeBindingInLoopBody = true; + if (isForStatement(container)) { + const varDeclList = getAncestor(symbol.valueDeclaration, SyntaxKind.VariableDeclarationList); + if (varDeclList && varDeclList.parent === container) { + const part = getPartOfForStatementContainingNode(node.parent, container); + if (part) { + const links = getNodeLinks(part); + links.flags |= NodeCheckFlags.ContainsCapturedBlockScopeBinding; + + const capturedBindings = links.capturedBlockScopeBindings || (links.capturedBlockScopeBindings = []); + pushIfUnique(capturedBindings, symbol); + + if (part === container.initializer) { + capturesBlockScopeBindingInLoopBody = false; // Initializer is outside of loop body + } + } + } + } + if (capturesBlockScopeBindingInLoopBody) { + getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; + } + } + + // mark variables that are declared in loop initializer and reassigned inside the body of ForStatement. + // if body of ForStatement will be converted to function then we'll need a extra machinery to propagate reassigned values back. + if (isForStatement(container)) { + const varDeclList = getAncestor(symbol.valueDeclaration, SyntaxKind.VariableDeclarationList); + if (varDeclList && varDeclList.parent === container && isAssignedInBodyOfForStatement(node, container)) { + getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.NeedsLoopOutParameter; + } + } + + // set 'declared inside loop' bit on the block-scoped binding + getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + } + + if (isCaptured) { + getNodeLinks(symbol.valueDeclaration).flags |= NodeCheckFlags.CapturedBlockScopedBinding; + } + } + + function isBindingCapturedByNode(node: Node, decl: VariableDeclaration | BindingElement) { + const links = getNodeLinks(node); + return !!links && contains(links.capturedBlockScopeBindings, getSymbolOfDeclaration(decl)); + } + + function isAssignedInBodyOfForStatement(node: Identifier, container: ForStatement): boolean { + // skip parenthesized nodes + let current: Node = node; + while (current.parent.kind === SyntaxKind.ParenthesizedExpression) { + current = current.parent; + } + + // check if node is used as LHS in some assignment expression + let isAssigned = false; + if (isAssignmentTarget(current)) { + isAssigned = true; + } + else if ((current.parent.kind === SyntaxKind.PrefixUnaryExpression || current.parent.kind === SyntaxKind.PostfixUnaryExpression)) { + const expr = current.parent as PrefixUnaryExpression | PostfixUnaryExpression; + isAssigned = expr.operator === SyntaxKind.PlusPlusToken || expr.operator === SyntaxKind.MinusMinusToken; + } + + if (!isAssigned) { + return false; + } + + // at this point we know that node is the target of assignment + // now check that modification happens inside the statement part of the ForStatement + return !!findAncestor(current, n => n === container ? "quit" : n === container.statement); + } + + function captureLexicalThis(node: Node, container: Node): void { + getNodeLinks(node).flags |= NodeCheckFlags.LexicalThis; + if (container.kind === SyntaxKind.PropertyDeclaration || container.kind === SyntaxKind.Constructor) { + const classNode = container.parent; + getNodeLinks(classNode).flags |= NodeCheckFlags.CaptureThis; + } + else { + getNodeLinks(container).flags |= NodeCheckFlags.CaptureThis; + } + } + + function findFirstSuperCall(node: Node): SuperCall | undefined { + return isSuperCall(node) ? node : + isFunctionLike(node) ? undefined : + forEachChild(node, findFirstSuperCall); + } + + /** + * Check if the given class-declaration extends null then return true. + * Otherwise, return false + * @param classDecl a class declaration to check if it extends null + */ + function classDeclarationExtendsNull(classDecl: ClassLikeDeclaration): boolean { + const classSymbol = getSymbolOfDeclaration(classDecl); + const classInstanceType = getDeclaredTypeOfSymbol(classSymbol) as InterfaceType; + const baseConstructorType = getBaseConstructorTypeOfClass(classInstanceType); + + return baseConstructorType === nullWideningType; + } + + function checkThisBeforeSuper(node: Node, container: Node, diagnosticMessage: DiagnosticMessage) { + const containingClassDecl = container.parent as ClassDeclaration; + const baseTypeNode = getClassExtendsHeritageElement(containingClassDecl); + + // If a containing class does not have extends clause or the class extends null + // skip checking whether super statement is called before "this" accessing. + if (baseTypeNode && !classDeclarationExtendsNull(containingClassDecl)) { + if (canHaveFlowNode(node) && node.flowNode && !isPostSuperFlowNode(node.flowNode, /*noCacheCheck*/ false)) { + error(node, diagnosticMessage); + } + } + } + + function checkThisInStaticClassFieldInitializerInDecoratedClass(thisExpression: Node, container: Node) { + if ( + isPropertyDeclaration(container) && hasStaticModifier(container) && legacyDecorators && + container.initializer && textRangeContainsPositionInclusive(container.initializer, thisExpression.pos) && hasDecorators(container.parent) + ) { + error(thisExpression, Diagnostics.Cannot_use_this_in_a_static_property_initializer_of_a_decorated_class); + } + } + + function checkThisExpression(node: Node): Type { + const isNodeInTypeQuery = isInTypeQuery(node); + // Stop at the first arrow function so that we can + // tell whether 'this' needs to be captured. + let container = getThisContainer(node, /*includeArrowFunctions*/ true, /*includeClassComputedPropertyName*/ true); + let capturedByArrowFunction = false; + let thisInComputedPropertyName = false; + + if (container.kind === SyntaxKind.Constructor) { + checkThisBeforeSuper(node, container, Diagnostics.super_must_be_called_before_accessing_this_in_the_constructor_of_a_derived_class); + } + + while (true) { + // Now skip arrow functions to get the "real" owner of 'this'. + if (container.kind === SyntaxKind.ArrowFunction) { + container = getThisContainer(container, /*includeArrowFunctions*/ false, !thisInComputedPropertyName); + capturedByArrowFunction = true; + } + + if (container.kind === SyntaxKind.ComputedPropertyName) { + container = getThisContainer(container, !capturedByArrowFunction, /*includeClassComputedPropertyName*/ false); + thisInComputedPropertyName = true; + continue; + } + + break; + } + + checkThisInStaticClassFieldInitializerInDecoratedClass(node, container); + if (thisInComputedPropertyName) { + error(node, Diagnostics.this_cannot_be_referenced_in_a_computed_property_name); + } + else { + switch (container.kind) { + case SyntaxKind.ModuleDeclaration: + error(node, Diagnostics.this_cannot_be_referenced_in_a_module_or_namespace_body); + // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks + break; + case SyntaxKind.EnumDeclaration: + error(node, Diagnostics.this_cannot_be_referenced_in_current_location); + // do not return here so in case if lexical this is captured - it will be reflected in flags on NodeLinks + break; + } + } + + // When targeting es6, mark that we'll need to capture `this` in its lexically bound scope. + if (!isNodeInTypeQuery && capturedByArrowFunction && languageVersion < ScriptTarget.ES2015) { + captureLexicalThis(node, container); + } + + const type = tryGetThisTypeAt(node, /*includeGlobalThis*/ true, container); + if (noImplicitThis) { + const globalThisType = getTypeOfSymbol(globalThisSymbol); + if (type === globalThisType && capturedByArrowFunction) { + error(node, Diagnostics.The_containing_arrow_function_captures_the_global_value_of_this); + } + else if (!type) { + // With noImplicitThis, functions may not reference 'this' if it has type 'any' + const diag = error(node, Diagnostics.this_implicitly_has_type_any_because_it_does_not_have_a_type_annotation); + if (!isSourceFile(container)) { + const outsideThis = tryGetThisTypeAt(container); + if (outsideThis && outsideThis !== globalThisType) { + addRelatedInfo(diag, createDiagnosticForNode(container, Diagnostics.An_outer_value_of_this_is_shadowed_by_this_container)); + } + } + } + } + return type || anyType; + } + + function tryGetThisTypeAt(node: Node, includeGlobalThis = true, container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false)): Type | undefined { + const isInJS = isInJSFile(node); + if ( + isFunctionLike(container) && + (!isInParameterInitializerBeforeContainingFunction(node) || getThisParameter(container)) + ) { + let thisType = getThisTypeOfDeclaration(container) || isInJS && getTypeForThisExpressionFromJSDoc(container); + // Note: a parameter initializer should refer to class-this unless function-this is explicitly annotated. + // If this is a function in a JS file, it might be a class method. + if (!thisType) { + const className = getClassNameFromPrototypeMethod(container); + if (isInJS && className) { + const classSymbol = checkExpression(className).symbol; + if (classSymbol && classSymbol.members && (classSymbol.flags & SymbolFlags.Function)) { + thisType = (getDeclaredTypeOfSymbol(classSymbol) as InterfaceType).thisType; + } + } + else if (isJSConstructor(container)) { + thisType = (getDeclaredTypeOfSymbol(getMergedSymbol(container.symbol)) as InterfaceType).thisType; + } + thisType ||= getContextualThisParameterType(container); + } + + if (thisType) { + return getFlowTypeOfReference(node, thisType); + } + } + + if (isClassLike(container.parent)) { + const symbol = getSymbolOfDeclaration(container.parent); + const type = isStatic(container) ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!; + return getFlowTypeOfReference(node, type); + } + + if (isSourceFile(container)) { + // look up in the source file's locals or exports + if (container.commonJsModuleIndicator) { + const fileSymbol = getSymbolOfDeclaration(container); + return fileSymbol && getTypeOfSymbol(fileSymbol); + } + else if (container.externalModuleIndicator) { + // TODO: Maybe issue a better error than 'object is possibly undefined' + return undefinedType; + } + else if (includeGlobalThis) { + return getTypeOfSymbol(globalThisSymbol); + } + } + } + + function getExplicitThisType(node: Expression) { + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + if (isFunctionLike(container)) { + const signature = getSignatureFromDeclaration(container); + if (signature.thisParameter) { + return getExplicitTypeOfSymbol(signature.thisParameter); + } + } + if (isClassLike(container.parent)) { + const symbol = getSymbolOfDeclaration(container.parent); + return isStatic(container) ? getTypeOfSymbol(symbol) : (getDeclaredTypeOfSymbol(symbol) as InterfaceType).thisType!; + } + } + + function getClassNameFromPrototypeMethod(container: Node) { + // Check if it's the RHS of a x.prototype.y = function [name]() { .... } + if ( + container.kind === SyntaxKind.FunctionExpression && + isBinaryExpression(container.parent) && + getAssignmentDeclarationKind(container.parent) === AssignmentDeclarationKind.PrototypeProperty + ) { + // Get the 'x' of 'x.prototype.y = container' + return ((container.parent // x.prototype.y = container + .left as PropertyAccessExpression) // x.prototype.y + .expression as PropertyAccessExpression) // x.prototype + .expression; // x + } + // x.prototype = { method() { } } + else if ( + container.kind === SyntaxKind.MethodDeclaration && + container.parent.kind === SyntaxKind.ObjectLiteralExpression && + isBinaryExpression(container.parent.parent) && + getAssignmentDeclarationKind(container.parent.parent) === AssignmentDeclarationKind.Prototype + ) { + return (container.parent.parent.left as PropertyAccessExpression).expression; + } + // x.prototype = { method: function() { } } + else if ( + container.kind === SyntaxKind.FunctionExpression && + container.parent.kind === SyntaxKind.PropertyAssignment && + container.parent.parent.kind === SyntaxKind.ObjectLiteralExpression && + isBinaryExpression(container.parent.parent.parent) && + getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.Prototype + ) { + return (container.parent.parent.parent.left as PropertyAccessExpression).expression; + } + // Object.defineProperty(x, "method", { value: function() { } }); + // Object.defineProperty(x, "method", { set: (x: () => void) => void }); + // Object.defineProperty(x, "method", { get: () => function() { }) }); + else if ( + container.kind === SyntaxKind.FunctionExpression && + isPropertyAssignment(container.parent) && + isIdentifier(container.parent.name) && + (container.parent.name.escapedText === "value" || container.parent.name.escapedText === "get" || container.parent.name.escapedText === "set") && + isObjectLiteralExpression(container.parent.parent) && + isCallExpression(container.parent.parent.parent) && + container.parent.parent.parent.arguments[2] === container.parent.parent && + getAssignmentDeclarationKind(container.parent.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty + ) { + return (container.parent.parent.parent.arguments[0] as PropertyAccessExpression).expression; + } + // Object.defineProperty(x, "method", { value() { } }); + // Object.defineProperty(x, "method", { set(x: () => void) {} }); + // Object.defineProperty(x, "method", { get() { return () => {} } }); + else if ( + isMethodDeclaration(container) && + isIdentifier(container.name) && + (container.name.escapedText === "value" || container.name.escapedText === "get" || container.name.escapedText === "set") && + isObjectLiteralExpression(container.parent) && + isCallExpression(container.parent.parent) && + container.parent.parent.arguments[2] === container.parent && + getAssignmentDeclarationKind(container.parent.parent) === AssignmentDeclarationKind.ObjectDefinePrototypeProperty + ) { + return (container.parent.parent.arguments[0] as PropertyAccessExpression).expression; + } + } + + function getTypeForThisExpressionFromJSDoc(node: SignatureDeclaration) { + const thisTag = getJSDocThisTag(node); + if (thisTag && thisTag.typeExpression) { + return getTypeFromTypeNode(thisTag.typeExpression); + } + const signature = getSignatureOfTypeTag(node); + if (signature) { + return getThisTypeOfSignature(signature); + } + } + + function isInConstructorArgumentInitializer(node: Node, constructorDecl: Node): boolean { + return !!findAncestor(node, n => isFunctionLikeDeclaration(n) ? "quit" : n.kind === SyntaxKind.Parameter && n.parent === constructorDecl); + } + + function checkSuperExpression(node: Node): Type { + const isCallExpression = node.parent.kind === SyntaxKind.CallExpression && (node.parent as CallExpression).expression === node; + + const immediateContainer = getSuperContainer(node, /*stopOnFunctions*/ true); + let container = immediateContainer; + let needToCaptureLexicalThis = false; + let inAsyncFunction = false; + + // adjust the container reference in case if super is used inside arrow functions with arbitrarily deep nesting + if (!isCallExpression) { + while (container && container.kind === SyntaxKind.ArrowFunction) { + if (hasSyntacticModifier(container, ModifierFlags.Async)) inAsyncFunction = true; + container = getSuperContainer(container, /*stopOnFunctions*/ true); + needToCaptureLexicalThis = languageVersion < ScriptTarget.ES2015; + } + if (container && hasSyntacticModifier(container, ModifierFlags.Async)) inAsyncFunction = true; + } + + let nodeCheckFlag: NodeCheckFlags = 0; + + if (!container || !isLegalUsageOfSuperExpression(container)) { + // issue more specific error if super is used in computed property name + // class A { foo() { return "1" }} + // class B { + // [super.foo()]() {} + // } + const current = findAncestor(node, n => n === container ? "quit" : n.kind === SyntaxKind.ComputedPropertyName); + if (current && current.kind === SyntaxKind.ComputedPropertyName) { + error(node, Diagnostics.super_cannot_be_referenced_in_a_computed_property_name); + } + else if (isCallExpression) { + error(node, Diagnostics.Super_calls_are_not_permitted_outside_constructors_or_in_nested_functions_inside_constructors); + } + else if (!container || !container.parent || !(isClassLike(container.parent) || container.parent.kind === SyntaxKind.ObjectLiteralExpression)) { + error(node, Diagnostics.super_can_only_be_referenced_in_members_of_derived_classes_or_object_literal_expressions); + } + else { + error(node, Diagnostics.super_property_access_is_permitted_only_in_a_constructor_member_function_or_member_accessor_of_a_derived_class); + } + return errorType; + } + + if (!isCallExpression && immediateContainer!.kind === SyntaxKind.Constructor) { + checkThisBeforeSuper(node, container, Diagnostics.super_must_be_called_before_accessing_a_property_of_super_in_the_constructor_of_a_derived_class); + } + + if (isStatic(container) || isCallExpression) { + nodeCheckFlag = NodeCheckFlags.SuperStatic; + if ( + !isCallExpression && + languageVersion >= ScriptTarget.ES2015 && languageVersion <= ScriptTarget.ES2021 && + (isPropertyDeclaration(container) || isClassStaticBlockDeclaration(container)) + ) { + // for `super.x` or `super[x]` in a static initializer, mark all enclosing + // block scope containers so that we can report potential collisions with + // `Reflect`. + forEachEnclosingBlockScopeContainer(node.parent, current => { + if (!isSourceFile(current) || isExternalOrCommonJsModule(current)) { + getNodeLinks(current).flags |= NodeCheckFlags.ContainsSuperPropertyInStaticInitializer; + } + }); + } + } + else { + nodeCheckFlag = NodeCheckFlags.SuperInstance; + } + + getNodeLinks(node).flags |= nodeCheckFlag; + + // Due to how we emit async functions, we need to specialize the emit for an async method that contains a `super` reference. + // This is due to the fact that we emit the body of an async function inside of a generator function. As generator + // functions cannot reference `super`, we emit a helper inside of the method body, but outside of the generator. This helper + // uses an arrow function, which is permitted to reference `super`. + // + // There are two primary ways we can access `super` from within an async method. The first is getting the value of a property + // or indexed access on super, either as part of a right-hand-side expression or call expression. The second is when setting the value + // of a property or indexed access, either as part of an assignment expression or destructuring assignment. + // + // The simplest case is reading a value, in which case we will emit something like the following: + // + // // ts + // ... + // async asyncMethod() { + // let x = await super.asyncMethod(); + // return x; + // } + // ... + // + // // js + // ... + // asyncMethod() { + // const _super = Object.create(null, { + // asyncMethod: { get: () => super.asyncMethod }, + // }); + // return __awaiter(this, arguments, Promise, function *() { + // let x = yield _super.asyncMethod.call(this); + // return x; + // }); + // } + // ... + // + // The more complex case is when we wish to assign a value, especially as part of a destructuring assignment. As both cases + // are legal in ES6, but also likely less frequent, we only emit setters if there is an assignment: + // + // // ts + // ... + // async asyncMethod(ar: Promise) { + // [super.a, super.b] = await ar; + // } + // ... + // + // // js + // ... + // asyncMethod(ar) { + // const _super = Object.create(null, { + // a: { get: () => super.a, set: (v) => super.a = v }, + // b: { get: () => super.b, set: (v) => super.b = v } + // }; + // return __awaiter(this, arguments, Promise, function *() { + // [_super.a, _super.b] = yield ar; + // }); + // } + // ... + // + // Creating an object that has getter and setters instead of just an accessor function is required for destructuring assignments + // as a call expression cannot be used as the target of a destructuring assignment while a property access can. + // + // For element access expressions (`super[x]`), we emit a generic helper that forwards the element access in both situations. + if (container.kind === SyntaxKind.MethodDeclaration && inAsyncFunction) { + if (isSuperProperty(node.parent) && isAssignmentTarget(node.parent)) { + getNodeLinks(container).flags |= NodeCheckFlags.MethodWithSuperPropertyAssignmentInAsync; + } + else { + getNodeLinks(container).flags |= NodeCheckFlags.MethodWithSuperPropertyAccessInAsync; + } + } + + if (needToCaptureLexicalThis) { + // call expressions are allowed only in constructors so they should always capture correct 'this' + // super property access expressions can also appear in arrow functions - + // in this case they should also use correct lexical this + captureLexicalThis(node.parent, container); + } + + if (container.parent.kind === SyntaxKind.ObjectLiteralExpression) { + if (languageVersion < ScriptTarget.ES2015) { + error(node, Diagnostics.super_is_only_allowed_in_members_of_object_literal_expressions_when_option_target_is_ES2015_or_higher); + return errorType; + } + else { + // for object literal assume that type of 'super' is 'any' + return anyType; + } + } + + // at this point the only legal case for parent is ClassLikeDeclaration + const classLikeDeclaration = container.parent as ClassLikeDeclaration; + if (!getClassExtendsHeritageElement(classLikeDeclaration)) { + error(node, Diagnostics.super_can_only_be_referenced_in_a_derived_class); + return errorType; + } + + if (classDeclarationExtendsNull(classLikeDeclaration)) { + return isCallExpression ? errorType : nullWideningType; + } + + const classType = getDeclaredTypeOfSymbol(getSymbolOfDeclaration(classLikeDeclaration)) as InterfaceType; + const baseClassType = classType && getBaseTypes(classType)[0]; + if (!baseClassType) { + return errorType; + } + + if (container.kind === SyntaxKind.Constructor && isInConstructorArgumentInitializer(node, container)) { + // issue custom error message for super property access in constructor arguments (to be aligned with old compiler) + error(node, Diagnostics.super_cannot_be_referenced_in_constructor_arguments); + return errorType; + } + + return nodeCheckFlag === NodeCheckFlags.SuperStatic + ? getBaseConstructorTypeOfClass(classType) + : getTypeWithThisArgument(baseClassType, classType.thisType); + + function isLegalUsageOfSuperExpression(container: Node): boolean { + if (isCallExpression) { + // TS 1.0 SPEC (April 2014): 4.8.1 + // Super calls are only permitted in constructors of derived classes + return container.kind === SyntaxKind.Constructor; + } + else { + // TS 1.0 SPEC (April 2014) + // 'super' property access is allowed + // - In a constructor, instance member function, instance member accessor, or instance member variable initializer where this references a derived class instance + // - In a static member function or static member accessor + + // topmost container must be something that is directly nested in the class declaration\object literal expression + if (isClassLike(container.parent) || container.parent.kind === SyntaxKind.ObjectLiteralExpression) { + if (isStatic(container)) { + return container.kind === SyntaxKind.MethodDeclaration || + container.kind === SyntaxKind.MethodSignature || + container.kind === SyntaxKind.GetAccessor || + container.kind === SyntaxKind.SetAccessor || + container.kind === SyntaxKind.PropertyDeclaration || + container.kind === SyntaxKind.ClassStaticBlockDeclaration; + } + else { + return container.kind === SyntaxKind.MethodDeclaration || + container.kind === SyntaxKind.MethodSignature || + container.kind === SyntaxKind.GetAccessor || + container.kind === SyntaxKind.SetAccessor || + container.kind === SyntaxKind.PropertyDeclaration || + container.kind === SyntaxKind.PropertySignature || + container.kind === SyntaxKind.Constructor; + } + } + } + + return false; + } + } + + function getContainingObjectLiteral(func: SignatureDeclaration): ObjectLiteralExpression | undefined { + return (func.kind === SyntaxKind.MethodDeclaration || + func.kind === SyntaxKind.GetAccessor || + func.kind === SyntaxKind.SetAccessor) && func.parent.kind === SyntaxKind.ObjectLiteralExpression ? func.parent : + func.kind === SyntaxKind.FunctionExpression && func.parent.kind === SyntaxKind.PropertyAssignment ? func.parent.parent as ObjectLiteralExpression : + undefined; + } + + function getThisTypeArgument(type: Type): Type | undefined { + return getObjectFlags(type) & ObjectFlags.Reference && (type as TypeReference).target === globalThisType ? getTypeArguments(type as TypeReference)[0] : undefined; + } + + function getThisTypeFromContextualType(type: Type): Type | undefined { + return mapType(type, t => { + return t.flags & TypeFlags.Intersection ? forEach((t as IntersectionType).types, getThisTypeArgument) : getThisTypeArgument(t); + }); + } + + function getThisTypeOfObjectLiteralFromContextualType(containingLiteral: ObjectLiteralExpression, contextualType: Type | undefined) { + let literal = containingLiteral; + let type = contextualType; + while (type) { + const thisType = getThisTypeFromContextualType(type); + if (thisType) { + return thisType; + } + if (literal.parent.kind !== SyntaxKind.PropertyAssignment) { + break; + } + literal = literal.parent.parent as ObjectLiteralExpression; + type = getApparentTypeOfContextualType(literal, /*contextFlags*/ undefined); + } + } + + function getContextualThisParameterType(func: SignatureDeclaration): Type | undefined { + if (func.kind === SyntaxKind.ArrowFunction) { + return undefined; + } + if (isContextSensitiveFunctionOrObjectLiteralMethod(func)) { + const contextualSignature = getContextualSignature(func); + if (contextualSignature) { + const thisParameter = contextualSignature.thisParameter; + if (thisParameter) { + return getTypeOfSymbol(thisParameter); + } + } + } + const inJs = isInJSFile(func); + if (noImplicitThis || inJs) { + const containingLiteral = getContainingObjectLiteral(func); + if (containingLiteral) { + // We have an object literal method. Check if the containing object literal has a contextual type + // that includes a ThisType. If so, T is the contextual type for 'this'. We continue looking in + // any directly enclosing object literals. + const contextualType = getApparentTypeOfContextualType(containingLiteral, /*contextFlags*/ undefined); + const thisType = getThisTypeOfObjectLiteralFromContextualType(containingLiteral, contextualType); + if (thisType) { + return instantiateType(thisType, getMapperFromContext(getInferenceContext(containingLiteral))); + } + // There was no contextual ThisType for the containing object literal, so the contextual type + // for 'this' is the non-null form of the contextual type for the containing object literal or + // the type of the object literal itself. + return getWidenedType(contextualType ? getNonNullableType(contextualType) : checkExpressionCached(containingLiteral)); + } + // In an assignment of the form 'obj.xxx = function(...)' or 'obj[xxx] = function(...)', the + // contextual type for 'this' is 'obj'. + const parent = walkUpParenthesizedExpressions(func.parent); + if (isAssignmentExpression(parent)) { + const target = parent.left; + if (isAccessExpression(target)) { + const { expression } = target; + // Don't contextually type `this` as `exports` in `exports.Point = function(x, y) { this.x = x; this.y = y; }` + if (inJs && isIdentifier(expression)) { + const sourceFile = getSourceFileOfNode(parent); + if (sourceFile.commonJsModuleIndicator && getResolvedSymbol(expression) === sourceFile.symbol) { + return undefined; + } + } + + return getWidenedType(checkExpressionCached(expression)); + } + } + } + return undefined; + } + + // Return contextual type of parameter or undefined if no contextual type is available + function getContextuallyTypedParameterType(parameter: ParameterDeclaration): Type | undefined { + const func = parameter.parent; + if (!isContextSensitiveFunctionOrObjectLiteralMethod(func)) { + return undefined; + } + const iife = getImmediatelyInvokedFunctionExpression(func); + if (iife && iife.arguments) { + const args = getEffectiveCallArguments(iife); + const indexOfParameter = func.parameters.indexOf(parameter); + if (parameter.dotDotDotToken) { + return getSpreadArgumentType(args, indexOfParameter, args.length, anyType, /*context*/ undefined, CheckMode.Normal); + } + const links = getNodeLinks(iife); + const cached = links.resolvedSignature; + links.resolvedSignature = anySignature; + const type = indexOfParameter < args.length ? + getWidenedLiteralType(checkExpression(args[indexOfParameter])) : + parameter.initializer ? undefined : undefinedWideningType; + links.resolvedSignature = cached; + return type; + } + const contextualSignature = getContextualSignature(func); + if (contextualSignature) { + const index = func.parameters.indexOf(parameter) - (getThisParameter(func) ? 1 : 0); + return parameter.dotDotDotToken && lastOrUndefined(func.parameters) === parameter ? + getRestTypeAtPosition(contextualSignature, index) : + tryGetTypeAtPosition(contextualSignature, index); + } + } + + function getContextualTypeForVariableLikeDeclaration(declaration: VariableLikeDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + const typeNode = getEffectiveTypeAnnotationNode(declaration) || (isInJSFile(declaration) ? tryGetJSDocSatisfiesTypeNode(declaration) : undefined); + if (typeNode) { + return getTypeFromTypeNode(typeNode); + } + switch (declaration.kind) { + case SyntaxKind.Parameter: + return getContextuallyTypedParameterType(declaration); + case SyntaxKind.BindingElement: + return getContextualTypeForBindingElement(declaration, contextFlags); + case SyntaxKind.PropertyDeclaration: + if (isStatic(declaration)) { + return getContextualTypeForStaticPropertyDeclaration(declaration, contextFlags); + } + // By default, do nothing and return undefined - only the above cases have context implied by a parent + } + } + + function getContextualTypeForBindingElement(declaration: BindingElement, contextFlags: ContextFlags | undefined): Type | undefined { + const parent = declaration.parent.parent; + const name = declaration.propertyName || declaration.name; + const parentType = getContextualTypeForVariableLikeDeclaration(parent, contextFlags) || + parent.kind !== SyntaxKind.BindingElement && parent.initializer && checkDeclarationInitializer(parent, declaration.dotDotDotToken ? CheckMode.RestBindingElement : CheckMode.Normal); + if (!parentType || isBindingPattern(name) || isComputedNonLiteralName(name)) return undefined; + if (parent.name.kind === SyntaxKind.ArrayBindingPattern) { + const index = indexOfNode(declaration.parent.elements, declaration); + if (index < 0) return undefined; + return getContextualTypeForElementExpression(parentType, index); + } + const nameType = getLiteralTypeFromPropertyName(name); + if (isTypeUsableAsPropertyName(nameType)) { + const text = getPropertyNameFromType(nameType); + return getTypeOfPropertyOfType(parentType, text); + } + } + + function getContextualTypeForStaticPropertyDeclaration(declaration: PropertyDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + const parentType = isExpression(declaration.parent) && getContextualType(declaration.parent, contextFlags); + if (!parentType) return undefined; + return getTypeOfPropertyOfContextualType(parentType, getSymbolOfDeclaration(declaration).escapedName); + } + + // In a variable, parameter or property declaration with a type annotation, + // the contextual type of an initializer expression is the type of the variable, parameter or property. + // Otherwise, in a parameter declaration of a contextually typed function expression, + // the contextual type of an initializer expression is the contextual type of the parameter. + // Otherwise, in a variable or parameter declaration with a binding pattern name, + // the contextual type of an initializer expression is the type implied by the binding pattern. + // Otherwise, in a binding pattern inside a variable or parameter declaration, + // the contextual type of an initializer expression is the type annotation of the containing declaration, if present. + function getContextualTypeForInitializerExpression(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const declaration = node.parent as VariableLikeDeclaration; + if (hasInitializer(declaration) && node === declaration.initializer) { + const result = getContextualTypeForVariableLikeDeclaration(declaration, contextFlags); + if (result) { + return result; + } + if (!(contextFlags! & ContextFlags.SkipBindingPatterns) && isBindingPattern(declaration.name) && declaration.name.elements.length > 0) { + return getTypeFromBindingPattern(declaration.name, /*includePatternInType*/ true, /*reportErrors*/ false); + } + } + return undefined; + } + + function getContextualTypeForReturnExpression(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const func = getContainingFunction(node); + if (func) { + let contextualReturnType = getContextualReturnType(func, contextFlags); + if (contextualReturnType) { + const functionFlags = getFunctionFlags(func); + if (functionFlags & FunctionFlags.Generator) { // Generator or AsyncGenerator function + const isAsyncGenerator = (functionFlags & FunctionFlags.Async) !== 0; + if (contextualReturnType.flags & TypeFlags.Union) { + contextualReturnType = filterType(contextualReturnType, type => !!getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, type, isAsyncGenerator)); + } + const iterationReturnType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, contextualReturnType, (functionFlags & FunctionFlags.Async) !== 0); + if (!iterationReturnType) { + return undefined; + } + contextualReturnType = iterationReturnType; + // falls through to unwrap Promise for AsyncGenerators + } + + if (functionFlags & FunctionFlags.Async) { // Async function or AsyncGenerator function + // Get the awaited type without the `Awaited` alias + const contextualAwaitedType = mapType(contextualReturnType, getAwaitedTypeNoAlias); + return contextualAwaitedType && getUnionType([contextualAwaitedType, createPromiseLikeType(contextualAwaitedType)]); + } + + return contextualReturnType; // Regular function or Generator function + } + } + return undefined; + } + + function getContextualTypeForAwaitOperand(node: AwaitExpression, contextFlags: ContextFlags | undefined): Type | undefined { + const contextualType = getContextualType(node, contextFlags); + if (contextualType) { + const contextualAwaitedType = getAwaitedTypeNoAlias(contextualType); + return contextualAwaitedType && getUnionType([contextualAwaitedType, createPromiseLikeType(contextualAwaitedType)]); + } + return undefined; + } + + function getContextualTypeForYieldOperand(node: YieldExpression, contextFlags: ContextFlags | undefined): Type | undefined { + const func = getContainingFunction(node); + if (func) { + const functionFlags = getFunctionFlags(func); + let contextualReturnType = getContextualReturnType(func, contextFlags); + if (contextualReturnType) { + const isAsyncGenerator = (functionFlags & FunctionFlags.Async) !== 0; + if (!node.asteriskToken && contextualReturnType.flags & TypeFlags.Union) { + contextualReturnType = filterType(contextualReturnType, type => !!getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, type, isAsyncGenerator)); + } + if (node.asteriskToken) { + const iterationTypes = getIterationTypesOfGeneratorFunctionReturnType(contextualReturnType, isAsyncGenerator); + const yieldType = iterationTypes?.yieldType ?? silentNeverType; + const returnType = getContextualType(node, contextFlags) ?? silentNeverType; + const nextType = iterationTypes?.nextType ?? unknownType; + const generatorType = createGeneratorType(yieldType, returnType, nextType, /*isAsyncGenerator*/ false); + if (isAsyncGenerator) { + const asyncGeneratorType = createGeneratorType(yieldType, returnType, nextType, /*isAsyncGenerator*/ true); + return getUnionType([generatorType, asyncGeneratorType]); + } + return generatorType; + } + return getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Yield, contextualReturnType, isAsyncGenerator); + } + } + + return undefined; + } + + function isInParameterInitializerBeforeContainingFunction(node: Node) { + let inBindingInitializer = false; + while (node.parent && !isFunctionLike(node.parent)) { + if (isParameter(node.parent) && (inBindingInitializer || node.parent.initializer === node)) { + return true; + } + if (isBindingElement(node.parent) && node.parent.initializer === node) { + inBindingInitializer = true; + } + + node = node.parent; + } + + return false; + } + + function getContextualIterationType(kind: IterationTypeKind, functionDecl: SignatureDeclaration): Type | undefined { + const isAsync = !!(getFunctionFlags(functionDecl) & FunctionFlags.Async); + const contextualReturnType = getContextualReturnType(functionDecl, /*contextFlags*/ undefined); + if (contextualReturnType) { + return getIterationTypeOfGeneratorFunctionReturnType(kind, contextualReturnType, isAsync) + || undefined; + } + + return undefined; + } + + function getContextualReturnType(functionDecl: SignatureDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + // If the containing function has a return type annotation, is a constructor, or is a get accessor whose + // corresponding set accessor has a type annotation, return statements in the function are contextually typed + const returnType = getReturnTypeFromAnnotation(functionDecl); + if (returnType) { + return returnType; + } + // Otherwise, if the containing function is contextually typed by a function type with exactly one call signature + // and that call signature is non-generic, return statements are contextually typed by the return type of the signature + const signature = getContextualSignatureForFunctionLikeDeclaration(functionDecl as FunctionExpression); + if (signature && !isResolvingReturnTypeOfSignature(signature)) { + const returnType = getReturnTypeOfSignature(signature); + const functionFlags = getFunctionFlags(functionDecl); + if (functionFlags & FunctionFlags.Generator) { + return filterType(returnType, t => { + return !!(t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.InstantiableNonPrimitive)) || checkGeneratorInstantiationAssignabilityToReturnType(t, functionFlags, /*errorNode*/ undefined); + }); + } + if (functionFlags & FunctionFlags.Async) { + return filterType(returnType, t => { + return !!(t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.InstantiableNonPrimitive)) || !!getAwaitedTypeOfPromise(t); + }); + } + return returnType; + } + const iife = getImmediatelyInvokedFunctionExpression(functionDecl); + if (iife) { + return getContextualType(iife, contextFlags); + } + return undefined; + } + + // In a typed function call, an argument or substitution expression is contextually typed by the type of the corresponding parameter. + function getContextualTypeForArgument(callTarget: CallLikeExpression, arg: Expression): Type | undefined { + const args = getEffectiveCallArguments(callTarget); + const argIndex = args.indexOf(arg); // -1 for e.g. the expression of a CallExpression, or the tag of a TaggedTemplateExpression + return argIndex === -1 ? undefined : getContextualTypeForArgumentAtIndex(callTarget, argIndex); + } + + function getContextualTypeForArgumentAtIndex(callTarget: CallLikeExpression, argIndex: number): Type { + if (isImportCall(callTarget)) { + return argIndex === 0 ? stringType : + argIndex === 1 ? getGlobalImportCallOptionsType(/*reportErrors*/ false) : + anyType; + } + + // If we're already in the process of resolving the given signature, don't resolve again as + // that could cause infinite recursion. Instead, return anySignature. + const signature = getNodeLinks(callTarget).resolvedSignature === resolvingSignature ? resolvingSignature : getResolvedSignature(callTarget); + + if (isJsxOpeningLikeElement(callTarget) && argIndex === 0) { + return getEffectiveFirstArgumentForJsxSignature(signature, callTarget); + } + const restIndex = signature.parameters.length - 1; + return signatureHasRestParameter(signature) && argIndex >= restIndex ? + getIndexedAccessType(getTypeOfSymbol(signature.parameters[restIndex]), getNumberLiteralType(argIndex - restIndex), AccessFlags.Contextual) : + getTypeAtPosition(signature, argIndex); + } + + function getContextualTypeForDecorator(decorator: Decorator): Type | undefined { + const signature = getDecoratorCallSignature(decorator); + return signature ? getOrCreateTypeFromSignature(signature) : undefined; + } + + function getContextualTypeForSubstitutionExpression(template: TemplateExpression, substitutionExpression: Expression) { + if (template.parent.kind === SyntaxKind.TaggedTemplateExpression) { + return getContextualTypeForArgument(template.parent as TaggedTemplateExpression, substitutionExpression); + } + + return undefined; + } + + function getContextualTypeForBinaryOperand(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const binaryExpression = node.parent as BinaryExpression; + const { left, operatorToken, right } = binaryExpression; + switch (operatorToken.kind) { + case SyntaxKind.EqualsToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: + case SyntaxKind.BarBarEqualsToken: + case SyntaxKind.QuestionQuestionEqualsToken: + return node === right ? getContextualTypeForAssignmentDeclaration(binaryExpression) : undefined; + case SyntaxKind.BarBarToken: + case SyntaxKind.QuestionQuestionToken: + // When an || expression has a contextual type, the operands are contextually typed by that type, except + // when that type originates in a binding pattern, the right operand is contextually typed by the type of + // the left operand. When an || expression has no contextual type, the right operand is contextually typed + // by the type of the left operand, except for the special case of Javascript declarations of the form + // `namespace.prop = namespace.prop || {}`. + const type = getContextualType(binaryExpression, contextFlags); + return node === right && (type && type.pattern || !type && !isDefaultedExpandoInitializer(binaryExpression)) ? + getTypeOfExpression(left) : type; + case SyntaxKind.AmpersandAmpersandToken: + case SyntaxKind.CommaToken: + return node === right ? getContextualType(binaryExpression, contextFlags) : undefined; + default: + return undefined; + } + } + + /** + * Try to find a resolved symbol for an expression without also resolving its type, as + * getSymbolAtLocation would (as that could be reentrant into contextual typing) + */ + function getSymbolForExpression(e: Expression) { + if (canHaveSymbol(e) && e.symbol) { + return e.symbol; + } + if (isIdentifier(e)) { + return getResolvedSymbol(e); + } + if (isPropertyAccessExpression(e)) { + const lhsType = getTypeOfExpression(e.expression); + return isPrivateIdentifier(e.name) ? tryGetPrivateIdentifierPropertyOfType(lhsType, e.name) : getPropertyOfType(lhsType, e.name.escapedText); + } + if (isElementAccessExpression(e)) { + const propType = checkExpressionCached(e.argumentExpression); + if (!isTypeUsableAsPropertyName(propType)) { + return undefined; + } + const lhsType = getTypeOfExpression(e.expression); + return getPropertyOfType(lhsType, getPropertyNameFromType(propType)); + } + return undefined; + + function tryGetPrivateIdentifierPropertyOfType(type: Type, id: PrivateIdentifier) { + const lexicallyScopedSymbol = lookupSymbolForPrivateIdentifierDeclaration(id.escapedText, id); + return lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(type, lexicallyScopedSymbol); + } + } + + // In an assignment expression, the right operand is contextually typed by the type of the left operand. + // Don't do this for assignment declarations unless there is a type tag on the assignment, to avoid circularity from checking the right operand. + function getContextualTypeForAssignmentDeclaration(binaryExpression: BinaryExpression): Type | undefined { + const kind = getAssignmentDeclarationKind(binaryExpression); + switch (kind) { + case AssignmentDeclarationKind.None: + case AssignmentDeclarationKind.ThisProperty: + const lhsSymbol = getSymbolForExpression(binaryExpression.left); + const decl = lhsSymbol && lhsSymbol.valueDeclaration; + // Unannotated, uninitialized property declarations have a type implied by their usage in the constructor. + // We avoid calling back into `getTypeOfExpression` and reentering contextual typing to avoid a bogus circularity error in that case. + if (decl && (isPropertyDeclaration(decl) || isPropertySignature(decl))) { + const overallAnnotation = getEffectiveTypeAnnotationNode(decl); + return (overallAnnotation && instantiateType(getTypeFromTypeNode(overallAnnotation), getSymbolLinks(lhsSymbol).mapper)) || + (isPropertyDeclaration(decl) ? decl.initializer && getTypeOfExpression(binaryExpression.left) : undefined); + } + if (kind === AssignmentDeclarationKind.None) { + return getTypeOfExpression(binaryExpression.left); + } + return getContextualTypeForThisPropertyAssignment(binaryExpression); + case AssignmentDeclarationKind.Property: + if (isPossiblyAliasedThisProperty(binaryExpression, kind)) { + return getContextualTypeForThisPropertyAssignment(binaryExpression); + } + // If `binaryExpression.left` was assigned a symbol, then this is a new declaration; otherwise it is an assignment to an existing declaration. + // See `bindStaticPropertyAssignment` in `binder.ts`. + else if (!canHaveSymbol(binaryExpression.left) || !binaryExpression.left.symbol) { + return getTypeOfExpression(binaryExpression.left); + } + else { + const decl = binaryExpression.left.symbol.valueDeclaration; + if (!decl) { + return undefined; + } + const lhs = cast(binaryExpression.left, isAccessExpression); + const overallAnnotation = getEffectiveTypeAnnotationNode(decl); + if (overallAnnotation) { + return getTypeFromTypeNode(overallAnnotation); + } + else if (isIdentifier(lhs.expression)) { + const id = lhs.expression; + const parentSymbol = resolveName(id, id.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true); + if (parentSymbol) { + const annotated = parentSymbol.valueDeclaration && getEffectiveTypeAnnotationNode(parentSymbol.valueDeclaration); + if (annotated) { + const nameStr = getElementOrPropertyAccessName(lhs); + if (nameStr !== undefined) { + return getTypeOfPropertyOfContextualType(getTypeFromTypeNode(annotated), nameStr); + } + } + return undefined; + } + } + return isInJSFile(decl) || decl === binaryExpression.left ? undefined : getTypeOfExpression(binaryExpression.left); + } + case AssignmentDeclarationKind.ExportsProperty: + case AssignmentDeclarationKind.Prototype: + case AssignmentDeclarationKind.PrototypeProperty: + case AssignmentDeclarationKind.ModuleExports: + let valueDeclaration: Declaration | undefined; + if (kind !== AssignmentDeclarationKind.ModuleExports) { + valueDeclaration = canHaveSymbol(binaryExpression.left) ? binaryExpression.left.symbol?.valueDeclaration : undefined; + } + valueDeclaration ||= binaryExpression.symbol?.valueDeclaration; + const annotated = valueDeclaration && getEffectiveTypeAnnotationNode(valueDeclaration); + return annotated ? getTypeFromTypeNode(annotated) : undefined; + case AssignmentDeclarationKind.ObjectDefinePropertyValue: + case AssignmentDeclarationKind.ObjectDefinePropertyExports: + case AssignmentDeclarationKind.ObjectDefinePrototypeProperty: + return Debug.fail("Does not apply"); + default: + return Debug.assertNever(kind); + } + } + + function isPossiblyAliasedThisProperty(declaration: BinaryExpression, kind = getAssignmentDeclarationKind(declaration)) { + if (kind === AssignmentDeclarationKind.ThisProperty) { + return true; + } + if (!isInJSFile(declaration) || kind !== AssignmentDeclarationKind.Property || !isIdentifier((declaration.left as AccessExpression).expression)) { + return false; + } + const name = ((declaration.left as AccessExpression).expression as Identifier).escapedText; + const symbol = resolveName(declaration.left, name, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true, /*excludeGlobals*/ true); + return isThisInitializedDeclaration(symbol?.valueDeclaration); + } + + function getContextualTypeForThisPropertyAssignment(binaryExpression: BinaryExpression): Type | undefined { + if (!binaryExpression.symbol) return getTypeOfExpression(binaryExpression.left); + if (binaryExpression.symbol.valueDeclaration) { + const annotated = getEffectiveTypeAnnotationNode(binaryExpression.symbol.valueDeclaration); + if (annotated) { + const type = getTypeFromTypeNode(annotated); + if (type) { + return type; + } + } + } + const thisAccess = cast(binaryExpression.left, isAccessExpression); + if (!isObjectLiteralMethod(getThisContainer(thisAccess.expression, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false))) { + return undefined; + } + const thisType = checkThisExpression(thisAccess.expression); + const nameStr = getElementOrPropertyAccessName(thisAccess); + return nameStr !== undefined && getTypeOfPropertyOfContextualType(thisType, nameStr) || undefined; + } + + function isCircularMappedProperty(symbol: Symbol) { + return !!(getCheckFlags(symbol) & CheckFlags.Mapped && !(symbol as MappedSymbol).links.type && findResolutionCycleStartIndex(symbol, TypeSystemPropertyName.Type) >= 0); + } + + function getTypeOfPropertyOfContextualType(type: Type, name: __String, nameType?: Type) { + return mapType(type, t => { + if (isGenericMappedType(t) && !t.declaration.nameType) { + const constraint = getConstraintTypeFromMappedType(t); + const constraintOfConstraint = getBaseConstraintOfType(constraint) || constraint; + const propertyNameType = nameType || getStringLiteralType(unescapeLeadingUnderscores(name)); + if (isTypeAssignableTo(propertyNameType, constraintOfConstraint)) { + return substituteIndexedMappedType(t, propertyNameType); + } + } + else if (t.flags & TypeFlags.StructuredType) { + const prop = getPropertyOfType(t, name); + if (prop) { + return isCircularMappedProperty(prop) ? undefined : removeMissingType(getTypeOfSymbol(prop), !!(prop.flags & SymbolFlags.Optional)); + } + if (isTupleType(t) && isNumericLiteralName(name) && +name >= 0) { + const restType = getElementTypeOfSliceOfTupleType(t, t.target.fixedLength, /*endSkipCount*/ 0, /*writing*/ false, /*noReductions*/ true); + if (restType) { + return restType; + } + } + return findApplicableIndexInfo(getIndexInfosOfStructuredType(t), nameType || getStringLiteralType(unescapeLeadingUnderscores(name)))?.type; + } + return undefined; + }, /*noReductions*/ true); + } + + // In an object literal contextually typed by a type T, the contextual type of a property assignment is the type of + // the matching property in T, if one exists. Otherwise, it is the type of the numeric index signature in T, if one + // exists. Otherwise, it is the type of the string index signature in T, if one exists. + function getContextualTypeForObjectLiteralMethod(node: MethodDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + Debug.assert(isObjectLiteralMethod(node)); + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return undefined; + } + return getContextualTypeForObjectLiteralElement(node, contextFlags); + } + + function getContextualTypeForObjectLiteralElement(element: ObjectLiteralElementLike, contextFlags: ContextFlags | undefined) { + const objectLiteral = element.parent as ObjectLiteralExpression; + const propertyAssignmentType = isPropertyAssignment(element) && getContextualTypeForVariableLikeDeclaration(element, contextFlags); + if (propertyAssignmentType) { + return propertyAssignmentType; + } + const type = getApparentTypeOfContextualType(objectLiteral, contextFlags); + if (type) { + if (hasBindableName(element)) { + // For a (non-symbol) computed property, there is no reason to look up the name + // in the type. It will just be "__computed", which does not appear in any + // SymbolTable. + const symbol = getSymbolOfDeclaration(element); + return getTypeOfPropertyOfContextualType(type, symbol.escapedName, getSymbolLinks(symbol).nameType); + } + if (hasDynamicName(element)) { + const name = getNameOfDeclaration(element); + if (name && isComputedPropertyName(name)) { + const exprType = checkExpression(name.expression); + const propType = isTypeUsableAsPropertyName(exprType) && getTypeOfPropertyOfContextualType(type, getPropertyNameFromType(exprType)); + if (propType) { + return propType; + } + } + } + if (element.name) { + const nameType = getLiteralTypeFromPropertyName(element.name); + // We avoid calling getApplicableIndexInfo here because it performs potentially expensive intersection reduction. + return mapType(type, t => findApplicableIndexInfo(getIndexInfosOfStructuredType(t), nameType)?.type, /*noReductions*/ true); + } + } + return undefined; + } + + function getSpreadIndices(elements: readonly Node[]) { + let first, last; + for (let i = 0; i < elements.length; i++) { + if (isSpreadElement(elements[i])) { + first ??= i; + last = i; + } + } + return { first, last }; + } + + function getContextualTypeForElementExpression(type: Type | undefined, index: number, length?: number, firstSpreadIndex?: number, lastSpreadIndex?: number): Type | undefined { + return type && mapType(type, t => { + if (isTupleType(t)) { + // If index is before any spread element and within the fixed part of the contextual tuple type, return + // the type of the contextual tuple element. + if ((firstSpreadIndex === undefined || index < firstSpreadIndex) && index < t.target.fixedLength) { + return removeMissingType(getTypeArguments(t)[index], !!(t.target.elementFlags[index] && ElementFlags.Optional)); + } + // When the length is known and the index is after all spread elements we compute the offset from the element + // to the end and the number of ending fixed elements in the contextual tuple type. + const offset = length !== undefined && (lastSpreadIndex === undefined || index > lastSpreadIndex) ? length - index : 0; + const fixedEndLength = offset > 0 && (t.target.combinedFlags & ElementFlags.Variable) ? getEndElementCount(t.target, ElementFlags.Fixed) : 0; + // If the offset is within the ending fixed part of the contextual tuple type, return the type of the contextual + // tuple element. + if (offset > 0 && offset <= fixedEndLength) { + return getTypeArguments(t)[getTypeReferenceArity(t) - offset]; + } + // Return a union of the possible contextual element types with no subtype reduction. + return getElementTypeOfSliceOfTupleType(t, firstSpreadIndex === undefined ? t.target.fixedLength : Math.min(t.target.fixedLength, firstSpreadIndex), length === undefined || lastSpreadIndex === undefined ? fixedEndLength : Math.min(fixedEndLength, length - lastSpreadIndex), /*writing*/ false, /*noReductions*/ true); + } + // If element index is known and a contextual property with that name exists, return it. Otherwise return the + // iterated or element type of the contextual type. + return (!firstSpreadIndex || index < firstSpreadIndex) && getTypeOfPropertyOfContextualType(t, "" + index as __String) || + getIteratedTypeOrElementType(IterationUse.Element, t, undefinedType, /*errorNode*/ undefined, /*checkAssignability*/ false); + }, /*noReductions*/ true); + } + + // In a contextually typed conditional expression, the true/false expressions are contextually typed by the same type. + function getContextualTypeForConditionalOperand(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + const conditional = node.parent as ConditionalExpression; + return node === conditional.whenTrue || node === conditional.whenFalse ? getContextualType(conditional, contextFlags) : undefined; + } + + function getContextualTypeForChildJsxExpression(node: JsxElement, child: JsxChild, contextFlags: ContextFlags | undefined) { + const attributesType = getApparentTypeOfContextualType(node.openingElement.attributes, contextFlags); + // JSX expression is in children of JSX Element, we will look for an "children" attribute (we get the name from JSX.ElementAttributesProperty) + const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + if (!(attributesType && !isTypeAny(attributesType) && jsxChildrenPropertyName && jsxChildrenPropertyName !== "")) { + return undefined; + } + const realChildren = getSemanticJsxChildren(node.children); + const childIndex = realChildren.indexOf(child); + const childFieldType = getTypeOfPropertyOfContextualType(attributesType, jsxChildrenPropertyName); + return childFieldType && (realChildren.length === 1 ? childFieldType : mapType(childFieldType, t => { + if (isArrayLikeType(t)) { + return getIndexedAccessType(t, getNumberLiteralType(childIndex)); + } + else { + return t; + } + }, /*noReductions*/ true)); + } + + function getContextualTypeForJsxExpression(node: JsxExpression, contextFlags: ContextFlags | undefined): Type | undefined { + const exprParent = node.parent; + return isJsxAttributeLike(exprParent) + ? getContextualType(node, contextFlags) + : isJsxElement(exprParent) + ? getContextualTypeForChildJsxExpression(exprParent, node, contextFlags) + : undefined; + } + + function getContextualTypeForJsxAttribute(attribute: JsxAttribute | JsxSpreadAttribute, contextFlags: ContextFlags | undefined): Type | undefined { + // When we trying to resolve JsxOpeningLikeElement as a stateless function element, we will already give its attributes a contextual type + // which is a type of the parameter of the signature we are trying out. + // If there is no contextual type (e.g. we are trying to resolve stateful component), get attributes type from resolving element's tagName + if (isJsxAttribute(attribute)) { + const attributesType = getApparentTypeOfContextualType(attribute.parent, contextFlags); + if (!attributesType || isTypeAny(attributesType)) { + return undefined; + } + return getTypeOfPropertyOfContextualType(attributesType, getEscapedTextOfJsxAttributeName(attribute.name)); + } + else { + return getContextualType(attribute.parent, contextFlags); + } + } + + // Return true if the given expression is possibly a discriminant value. We limit the kinds of + // expressions we check to those that don't depend on their contextual type in order not to cause + // recursive (and possibly infinite) invocations of getContextualType. + function isPossiblyDiscriminantValue(node: Expression): boolean { + switch (node.kind) { + case SyntaxKind.StringLiteral: + case SyntaxKind.NumericLiteral: + case SyntaxKind.BigIntLiteral: + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.TemplateExpression: + case SyntaxKind.TrueKeyword: + case SyntaxKind.FalseKeyword: + case SyntaxKind.NullKeyword: + case SyntaxKind.Identifier: + case SyntaxKind.UndefinedKeyword: + return true; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ParenthesizedExpression: + return isPossiblyDiscriminantValue((node as PropertyAccessExpression | ParenthesizedExpression).expression); + case SyntaxKind.JsxExpression: + return !(node as JsxExpression).expression || isPossiblyDiscriminantValue((node as JsxExpression).expression!); + } + return false; + } + + function discriminateContextualTypeByObjectMembers(node: ObjectLiteralExpression, contextualType: UnionType) { + const key = `D${getNodeId(node)},${getTypeId(contextualType)}`; + return getCachedType(key) ?? setCachedType( + key, + getMatchingUnionConstituentForObjectLiteral(contextualType, node) ?? discriminateTypeByDiscriminableItems( + contextualType, + concatenate( + map( + filter(node.properties, (p): p is PropertyAssignment | ShorthandPropertyAssignment => { + if (!p.symbol) { + return false; + } + if (p.kind === SyntaxKind.PropertyAssignment) { + return isPossiblyDiscriminantValue(p.initializer) && isDiscriminantProperty(contextualType, p.symbol.escapedName); + } + if (p.kind === SyntaxKind.ShorthandPropertyAssignment) { + return isDiscriminantProperty(contextualType, p.symbol.escapedName); + } + return false; + }), + prop => ([() => getContextFreeTypeOfExpression(prop.kind === SyntaxKind.PropertyAssignment ? prop.initializer : prop.name), prop.symbol.escapedName] as const), + ), + map( + filter(getPropertiesOfType(contextualType), s => !!(s.flags & SymbolFlags.Optional) && !!node?.symbol?.members && !node.symbol.members.has(s.escapedName) && isDiscriminantProperty(contextualType, s.escapedName)), + s => [() => undefinedType, s.escapedName] as const, + ), + ), + isTypeAssignableTo, + ), + ); + } + + function discriminateContextualTypeByJSXAttributes(node: JsxAttributes, contextualType: UnionType) { + const key = `D${getNodeId(node)},${getTypeId(contextualType)}`; + const cached = getCachedType(key); + if (cached) return cached; + const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(node)); + return setCachedType( + key, + discriminateTypeByDiscriminableItems( + contextualType, + concatenate( + map( + filter(node.properties, p => !!p.symbol && p.kind === SyntaxKind.JsxAttribute && isDiscriminantProperty(contextualType, p.symbol.escapedName) && (!p.initializer || isPossiblyDiscriminantValue(p.initializer))), + prop => ([!(prop as JsxAttribute).initializer ? (() => trueType) : (() => getContextFreeTypeOfExpression((prop as JsxAttribute).initializer!)), prop.symbol.escapedName] as const), + ), + map( + filter(getPropertiesOfType(contextualType), s => { + if (!(s.flags & SymbolFlags.Optional) || !node?.symbol?.members) { + return false; + } + const element = node.parent.parent; + if (s.escapedName === jsxChildrenPropertyName && isJsxElement(element) && getSemanticJsxChildren(element.children).length) { + return false; + } + return !node.symbol.members.has(s.escapedName) && isDiscriminantProperty(contextualType, s.escapedName); + }), + s => [() => undefinedType, s.escapedName] as const, + ), + ), + isTypeAssignableTo, + ), + ); + } + + // Return the contextual type for a given expression node. During overload resolution, a contextual type may temporarily + // be "pushed" onto a node using the contextualType property. + function getApparentTypeOfContextualType(node: Expression | MethodDeclaration, contextFlags: ContextFlags | undefined): Type | undefined { + const contextualType = isObjectLiteralMethod(node) ? + getContextualTypeForObjectLiteralMethod(node, contextFlags) : + getContextualType(node, contextFlags); + const instantiatedType = instantiateContextualType(contextualType, node, contextFlags); + if (instantiatedType && !(contextFlags && contextFlags & ContextFlags.NoConstraints && instantiatedType.flags & TypeFlags.TypeVariable)) { + const apparentType = mapType( + instantiatedType, + // When obtaining apparent type of *contextual* type we don't want to get apparent type of mapped types. + // That would evaluate mapped types with array or tuple type constraints too eagerly + // and thus it would prevent `getTypeOfPropertyOfContextualType` from obtaining per-position contextual type for elements of array literal expressions. + // Apparent type of other mapped types is already the mapped type itself so we can just avoid calling `getApparentType` here for all mapped types. + t => getObjectFlags(t) & ObjectFlags.Mapped ? t : getApparentType(t), + /*noReductions*/ true, + ); + return apparentType.flags & TypeFlags.Union && isObjectLiteralExpression(node) ? discriminateContextualTypeByObjectMembers(node, apparentType as UnionType) : + apparentType.flags & TypeFlags.Union && isJsxAttributes(node) ? discriminateContextualTypeByJSXAttributes(node, apparentType as UnionType) : + apparentType; + } + } + + // If the given contextual type contains instantiable types and if a mapper representing + // return type inferences is available, instantiate those types using that mapper. + function instantiateContextualType(contextualType: Type | undefined, node: Node, contextFlags: ContextFlags | undefined): Type | undefined { + if (contextualType && maybeTypeOfKind(contextualType, TypeFlags.Instantiable)) { + const inferenceContext = getInferenceContext(node); + // If no inferences have been made, and none of the type parameters for which we are inferring + // specify default types, nothing is gained from instantiating as type parameters would just be + // replaced with their constraints similar to the apparent type. + if (inferenceContext && contextFlags! & ContextFlags.Signature && some(inferenceContext.inferences, hasInferenceCandidatesOrDefault)) { + // For contextual signatures we incorporate all inferences made so far, e.g. from return + // types as well as arguments to the left in a function call. + return instantiateInstantiableTypes(contextualType, inferenceContext.nonFixingMapper); + } + if (inferenceContext?.returnMapper) { + // For other purposes (e.g. determining whether to produce literal types) we only + // incorporate inferences made from the return type in a function call. We remove + // the 'boolean' type from the contextual type such that contextually typed boolean + // literals actually end up widening to 'boolean' (see #48363). + const type = instantiateInstantiableTypes(contextualType, inferenceContext.returnMapper); + return type.flags & TypeFlags.Union && containsType((type as UnionType).types, regularFalseType) && containsType((type as UnionType).types, regularTrueType) ? + filterType(type, t => t !== regularFalseType && t !== regularTrueType) : + type; + } + } + return contextualType; + } + + // This function is similar to instantiateType, except that (a) it only instantiates types that + // are classified as instantiable (i.e. it doesn't instantiate object types), and (b) it performs + // no reductions on instantiated union types. + function instantiateInstantiableTypes(type: Type, mapper: TypeMapper): Type { + if (type.flags & TypeFlags.Instantiable) { + return instantiateType(type, mapper); + } + if (type.flags & TypeFlags.Union) { + return getUnionType(map((type as UnionType).types, t => instantiateInstantiableTypes(t, mapper)), UnionReduction.None); + } + if (type.flags & TypeFlags.Intersection) { + return getIntersectionType(map((type as IntersectionType).types, t => instantiateInstantiableTypes(t, mapper))); + } + return type; + } + + /** + * Whoa! Do you really want to use this function? + * + * Unless you're trying to get the *non-apparent* type for a + * value-literal type or you're authoring relevant portions of this algorithm, + * you probably meant to use 'getApparentTypeOfContextualType'. + * Otherwise this may not be very useful. + * + * In cases where you *are* working on this function, you should understand + * when it is appropriate to use 'getContextualType' and 'getApparentTypeOfContextualType'. + * + * - Use 'getContextualType' when you are simply going to propagate the result to the expression. + * - Use 'getApparentTypeOfContextualType' when you're going to need the members of the type. + * + * @param node the expression whose contextual type will be returned. + * @returns the contextual type of an expression. + */ + function getContextualType(node: Expression, contextFlags: ContextFlags | undefined): Type | undefined { + if (node.flags & NodeFlags.InWithStatement) { + // We cannot answer semantic questions within a with block, do not proceed any further + return undefined; + } + // Cached contextual types are obtained with no ContextFlags, so we can only consult them for + // requests with no ContextFlags. + const index = findContextualNode(node, /*includeCaches*/ !contextFlags); + if (index >= 0) { + return contextualTypes[index]; + } + const { parent } = node; + switch (parent.kind) { + case SyntaxKind.VariableDeclaration: + case SyntaxKind.Parameter: + case SyntaxKind.PropertyDeclaration: + case SyntaxKind.PropertySignature: + case SyntaxKind.BindingElement: + return getContextualTypeForInitializerExpression(node, contextFlags); + case SyntaxKind.ArrowFunction: + case SyntaxKind.ReturnStatement: + return getContextualTypeForReturnExpression(node, contextFlags); + case SyntaxKind.YieldExpression: + return getContextualTypeForYieldOperand(parent as YieldExpression, contextFlags); + case SyntaxKind.AwaitExpression: + return getContextualTypeForAwaitOperand(parent as AwaitExpression, contextFlags); + case SyntaxKind.CallExpression: + case SyntaxKind.NewExpression: + return getContextualTypeForArgument(parent as CallExpression | NewExpression | Decorator, node); + case SyntaxKind.Decorator: + return getContextualTypeForDecorator(parent as Decorator); + case SyntaxKind.TypeAssertionExpression: + case SyntaxKind.AsExpression: + return isConstTypeReference((parent as AssertionExpression).type) ? getContextualType(parent as AssertionExpression, contextFlags) : getTypeFromTypeNode((parent as AssertionExpression).type); + case SyntaxKind.BinaryExpression: + return getContextualTypeForBinaryOperand(node, contextFlags); + case SyntaxKind.PropertyAssignment: + case SyntaxKind.ShorthandPropertyAssignment: + return getContextualTypeForObjectLiteralElement(parent as PropertyAssignment | ShorthandPropertyAssignment, contextFlags); + case SyntaxKind.SpreadAssignment: + return getContextualType(parent.parent as ObjectLiteralExpression, contextFlags); + case SyntaxKind.ArrayLiteralExpression: { + const arrayLiteral = parent as ArrayLiteralExpression; + const type = getApparentTypeOfContextualType(arrayLiteral, contextFlags); + const elementIndex = indexOfNode(arrayLiteral.elements, node); + const spreadIndices = getNodeLinks(arrayLiteral).spreadIndices ??= getSpreadIndices(arrayLiteral.elements); + return getContextualTypeForElementExpression(type, elementIndex, arrayLiteral.elements.length, spreadIndices.first, spreadIndices.last); + } + case SyntaxKind.ConditionalExpression: + return getContextualTypeForConditionalOperand(node, contextFlags); + case SyntaxKind.TemplateSpan: + Debug.assert(parent.parent.kind === SyntaxKind.TemplateExpression); + return getContextualTypeForSubstitutionExpression(parent.parent as TemplateExpression, node); + case SyntaxKind.ParenthesizedExpression: { + if (isInJSFile(parent)) { + if (isJSDocSatisfiesExpression(parent)) { + return getTypeFromTypeNode(getJSDocSatisfiesExpressionType(parent)); + } + // Like in `checkParenthesizedExpression`, an `/** @type {xyz} */` comment before a parenthesized expression acts as a type cast. + const typeTag = getJSDocTypeTag(parent); + if (typeTag && !isConstTypeReference(typeTag.typeExpression.type)) { + return getTypeFromTypeNode(typeTag.typeExpression.type); + } + } + return getContextualType(parent as ParenthesizedExpression, contextFlags); + } + case SyntaxKind.NonNullExpression: + return getContextualType(parent as NonNullExpression, contextFlags); + case SyntaxKind.SatisfiesExpression: + return getTypeFromTypeNode((parent as SatisfiesExpression).type); + case SyntaxKind.ExportAssignment: + return tryGetTypeFromEffectiveTypeNode(parent as ExportAssignment); + case SyntaxKind.JsxExpression: + return getContextualTypeForJsxExpression(parent as JsxExpression, contextFlags); + case SyntaxKind.JsxAttribute: + case SyntaxKind.JsxSpreadAttribute: + return getContextualTypeForJsxAttribute(parent as JsxAttribute | JsxSpreadAttribute, contextFlags); + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.JsxSelfClosingElement: + return getContextualJsxElementAttributesType(parent as JsxOpeningLikeElement, contextFlags); + case SyntaxKind.ImportAttribute: + return getContextualImportAttributeType(parent as ImportAttribute); + } + return undefined; + } + + function pushCachedContextualType(node: Expression) { + pushContextualType(node, getContextualType(node, /*contextFlags*/ undefined), /*isCache*/ true); + } + + function pushContextualType(node: Expression, type: Type | undefined, isCache: boolean) { + contextualTypeNodes[contextualTypeCount] = node; + contextualTypes[contextualTypeCount] = type; + contextualIsCache[contextualTypeCount] = isCache; + contextualTypeCount++; + } + + function popContextualType() { + contextualTypeCount--; + } + + function findContextualNode(node: Node, includeCaches: boolean) { + for (let i = contextualTypeCount - 1; i >= 0; i--) { + if (node === contextualTypeNodes[i] && (includeCaches || !contextualIsCache[i])) { + return i; + } + } + return -1; + } + + function pushInferenceContext(node: Node, inferenceContext: InferenceContext | undefined) { + inferenceContextNodes[inferenceContextCount] = node; + inferenceContexts[inferenceContextCount] = inferenceContext; + inferenceContextCount++; + } + + function popInferenceContext() { + inferenceContextCount--; + } + + function getInferenceContext(node: Node) { + for (let i = inferenceContextCount - 1; i >= 0; i--) { + if (isNodeDescendantOf(node, inferenceContextNodes[i])) { + return inferenceContexts[i]; + } + } + } + + function getContextualImportAttributeType(node: ImportAttribute) { + return getTypeOfPropertyOfContextualType(getGlobalImportAttributesType(/*reportErrors*/ false), getNameFromImportAttribute(node)); + } + + function getContextualJsxElementAttributesType(node: JsxOpeningLikeElement, contextFlags: ContextFlags | undefined) { + if (isJsxOpeningElement(node) && contextFlags !== ContextFlags.Completions) { + const index = findContextualNode(node.parent, /*includeCaches*/ !contextFlags); + if (index >= 0) { + // Contextually applied type is moved from attributes up to the outer jsx attributes so when walking up from the children they get hit + // _However_ to hit them from the _attributes_ we must look for them here; otherwise we'll used the declared type + // (as below) instead! + return contextualTypes[index]; + } + } + return getContextualTypeForArgumentAtIndex(node, 0); + } + + function getEffectiveFirstArgumentForJsxSignature(signature: Signature, node: JsxOpeningLikeElement) { + return getJsxReferenceKind(node) !== JsxReferenceKind.Component + ? getJsxPropsTypeFromCallSignature(signature, node) + : getJsxPropsTypeFromClassType(signature, node); + } + + function getJsxPropsTypeFromCallSignature(sig: Signature, context: JsxOpeningLikeElement) { + let propsType = getTypeOfFirstParameterOfSignatureWithFallback(sig, unknownType); + propsType = getJsxManagedAttributesFromLocatedAttributes(context, getJsxNamespaceAt(context), propsType); + const intrinsicAttribs = getJsxType(JsxNames.IntrinsicAttributes, context); + if (!isErrorType(intrinsicAttribs)) { + propsType = intersectTypes(intrinsicAttribs, propsType); + } + return propsType; + } + + function getJsxPropsTypeForSignatureFromMember(sig: Signature, forcedLookupLocation: __String) { + if (sig.compositeSignatures) { + // JSX Elements using the legacy `props`-field based lookup (eg, react class components) need to treat the `props` member as an input + // instead of an output position when resolving the signature. We need to go back to the input signatures of the composite signature, + // get the type of `props` on each return type individually, and then _intersect them_, rather than union them (as would normally occur + // for a union signature). It's an unfortunate quirk of looking in the output of the signature for the type we want to use for the input. + // The default behavior of `getTypeOfFirstParameterOfSignatureWithFallback` when no `props` member name is defined is much more sane. + const results: Type[] = []; + for (const signature of sig.compositeSignatures) { + const instance = getReturnTypeOfSignature(signature); + if (isTypeAny(instance)) { + return instance; + } + const propType = getTypeOfPropertyOfType(instance, forcedLookupLocation); + if (!propType) { + return; + } + results.push(propType); + } + return getIntersectionType(results); // Same result for both union and intersection signatures + } + const instanceType = getReturnTypeOfSignature(sig); + return isTypeAny(instanceType) ? instanceType : getTypeOfPropertyOfType(instanceType, forcedLookupLocation); + } + + function getStaticTypeOfReferencedJsxConstructor(context: JsxOpeningLikeElement) { + if (isJsxIntrinsicTagName(context.tagName)) { + const result = getIntrinsicAttributesTypeFromJsxOpeningLikeElement(context); + const fakeSignature = createSignatureForJSXIntrinsic(context, result); + return getOrCreateTypeFromSignature(fakeSignature); + } + const tagType = checkExpressionCached(context.tagName); + if (tagType.flags & TypeFlags.StringLiteral) { + const result = getIntrinsicAttributesTypeFromStringLiteralType(tagType as StringLiteralType, context); + if (!result) { + return errorType; + } + const fakeSignature = createSignatureForJSXIntrinsic(context, result); + return getOrCreateTypeFromSignature(fakeSignature); + } + return tagType; + } + + function getJsxManagedAttributesFromLocatedAttributes(context: JsxOpeningLikeElement, ns: Symbol, attributesType: Type) { + const managedSym = getJsxLibraryManagedAttributes(ns); + if (managedSym) { + const ctorType = getStaticTypeOfReferencedJsxConstructor(context); + const result = instantiateAliasOrInterfaceWithDefaults(managedSym, isInJSFile(context), ctorType, attributesType); + if (result) { + return result; + } + } + return attributesType; + } + + function getJsxPropsTypeFromClassType(sig: Signature, context: JsxOpeningLikeElement) { + const ns = getJsxNamespaceAt(context); + const forcedLookupLocation = getJsxElementPropertiesName(ns); + let attributesType = forcedLookupLocation === undefined + // If there is no type ElementAttributesProperty, return the type of the first parameter of the signature, which should be the props type + ? getTypeOfFirstParameterOfSignatureWithFallback(sig, unknownType) + : forcedLookupLocation === "" + // If there is no e.g. 'props' member in ElementAttributesProperty, use the element class type instead + ? getReturnTypeOfSignature(sig) + // Otherwise get the type of the property on the signature return type + : getJsxPropsTypeForSignatureFromMember(sig, forcedLookupLocation); + + if (!attributesType) { + // There is no property named 'props' on this instance type + if (!!forcedLookupLocation && !!length(context.attributes.properties)) { + error(context, Diagnostics.JSX_element_class_does_not_support_attributes_because_it_does_not_have_a_0_property, unescapeLeadingUnderscores(forcedLookupLocation)); + } + return unknownType; + } + + attributesType = getJsxManagedAttributesFromLocatedAttributes(context, ns, attributesType); + + if (isTypeAny(attributesType)) { + // Props is of type 'any' or unknown + return attributesType; + } + else { + // Normal case -- add in IntrinsicClassElements and IntrinsicElements + let apparentAttributesType = attributesType; + const intrinsicClassAttribs = getJsxType(JsxNames.IntrinsicClassAttributes, context); + if (!isErrorType(intrinsicClassAttribs)) { + const typeParams = getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(intrinsicClassAttribs.symbol); + const hostClassType = getReturnTypeOfSignature(sig); + let libraryManagedAttributeType: Type; + if (typeParams) { + // apply JSX.IntrinsicClassElements + const inferredArgs = fillMissingTypeArguments([hostClassType], typeParams, getMinTypeArgumentCount(typeParams), isInJSFile(context)); + libraryManagedAttributeType = instantiateType(intrinsicClassAttribs, createTypeMapper(typeParams, inferredArgs)); + } + // or JSX.IntrinsicClassElements has no generics. + else libraryManagedAttributeType = intrinsicClassAttribs; + apparentAttributesType = intersectTypes(libraryManagedAttributeType, apparentAttributesType); + } + + const intrinsicAttribs = getJsxType(JsxNames.IntrinsicAttributes, context); + if (!isErrorType(intrinsicAttribs)) { + apparentAttributesType = intersectTypes(intrinsicAttribs, apparentAttributesType); + } + + return apparentAttributesType; + } + } + + function getIntersectedSignatures(signatures: readonly Signature[]) { + return getStrictOptionValue(compilerOptions, "noImplicitAny") + ? reduceLeft( + signatures, + (left: Signature | undefined, right) => + left === right || !left ? left + : compareTypeParametersIdentical(left.typeParameters, right!.typeParameters) ? combineSignaturesOfIntersectionMembers(left, right!) + : undefined, + ) + : undefined; + } + + function combineIntersectionThisParam(left: Symbol | undefined, right: Symbol | undefined, mapper: TypeMapper | undefined): Symbol | undefined { + if (!left || !right) { + return left || right; + } + // A signature `this` type might be a read or a write position... It's very possible that it should be invariant + // and we should refuse to merge signatures if there are `this` types and they do not match. However, so as to be + // pessimistic when contextual typing, for now, we'll union the `this` types. + const thisType = getUnionType([getTypeOfSymbol(left), instantiateType(getTypeOfSymbol(right), mapper)]); + return createSymbolWithType(left, thisType); + } + + function combineIntersectionParameters(left: Signature, right: Signature, mapper: TypeMapper | undefined) { + const leftCount = getParameterCount(left); + const rightCount = getParameterCount(right); + const longest = leftCount >= rightCount ? left : right; + const shorter = longest === left ? right : left; + const longestCount = longest === left ? leftCount : rightCount; + const eitherHasEffectiveRest = hasEffectiveRestParameter(left) || hasEffectiveRestParameter(right); + const needsExtraRestElement = eitherHasEffectiveRest && !hasEffectiveRestParameter(longest); + const params = new Array(longestCount + (needsExtraRestElement ? 1 : 0)); + for (let i = 0; i < longestCount; i++) { + let longestParamType = tryGetTypeAtPosition(longest, i)!; + if (longest === right) { + longestParamType = instantiateType(longestParamType, mapper); + } + let shorterParamType = tryGetTypeAtPosition(shorter, i) || unknownType; + if (shorter === right) { + shorterParamType = instantiateType(shorterParamType, mapper); + } + const unionParamType = getUnionType([longestParamType, shorterParamType]); + const isRestParam = eitherHasEffectiveRest && !needsExtraRestElement && i === (longestCount - 1); + const isOptional = i >= getMinArgumentCount(longest) && i >= getMinArgumentCount(shorter); + const leftName = i >= leftCount ? undefined : getParameterNameAtPosition(left, i); + const rightName = i >= rightCount ? undefined : getParameterNameAtPosition(right, i); + + const paramName = leftName === rightName ? leftName : + !leftName ? rightName : + !rightName ? leftName : + undefined; + const paramSymbol = createSymbol( + SymbolFlags.FunctionScopedVariable | (isOptional && !isRestParam ? SymbolFlags.Optional : 0), + paramName || `arg${i}` as __String, + ); + paramSymbol.links.type = isRestParam ? createArrayType(unionParamType) : unionParamType; + params[i] = paramSymbol; + } + if (needsExtraRestElement) { + const restParamSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "args" as __String); + restParamSymbol.links.type = createArrayType(getTypeAtPosition(shorter, longestCount)); + if (shorter === right) { + restParamSymbol.links.type = instantiateType(restParamSymbol.links.type, mapper); + } + params[longestCount] = restParamSymbol; + } + return params; + } + + function combineSignaturesOfIntersectionMembers(left: Signature, right: Signature): Signature { + const typeParams = left.typeParameters || right.typeParameters; + let paramMapper: TypeMapper | undefined; + if (left.typeParameters && right.typeParameters) { + paramMapper = createTypeMapper(right.typeParameters, left.typeParameters); + // We just use the type parameter defaults from the first signature + } + const declaration = left.declaration; + const params = combineIntersectionParameters(left, right, paramMapper); + const thisParam = combineIntersectionThisParam(left.thisParameter, right.thisParameter, paramMapper); + const minArgCount = Math.max(left.minArgumentCount, right.minArgumentCount); + const result = createSignature( + declaration, + typeParams, + thisParam, + params, + /*resolvedReturnType*/ undefined, + /*resolvedTypePredicate*/ undefined, + minArgCount, + (left.flags | right.flags) & SignatureFlags.PropagatingFlags, + ); + result.compositeKind = TypeFlags.Intersection; + result.compositeSignatures = concatenate(left.compositeKind === TypeFlags.Intersection && left.compositeSignatures || [left], [right]); + if (paramMapper) { + result.mapper = left.compositeKind === TypeFlags.Intersection && left.mapper && left.compositeSignatures ? combineTypeMappers(left.mapper, paramMapper) : paramMapper; + } + return result; + } + + // If the given type is an object or union type with a single signature, and if that signature has at + // least as many parameters as the given function, return the signature. Otherwise return undefined. + function getContextualCallSignature(type: Type, node: SignatureDeclaration): Signature | undefined { + const signatures = getSignaturesOfType(type, SignatureKind.Call); + const applicableByArity = filter(signatures, s => !isAritySmaller(s, node)); + return applicableByArity.length === 1 ? applicableByArity[0] : getIntersectedSignatures(applicableByArity); + } + + /** If the contextual signature has fewer parameters than the function expression, do not use it */ + function isAritySmaller(signature: Signature, target: SignatureDeclaration) { + let targetParameterCount = 0; + for (; targetParameterCount < target.parameters.length; targetParameterCount++) { + const param = target.parameters[targetParameterCount]; + if (param.initializer || param.questionToken || param.dotDotDotToken || isJSDocOptionalParameter(param)) { + break; + } + } + if (target.parameters.length && parameterIsThisKeyword(target.parameters[0])) { + targetParameterCount--; + } + return !hasEffectiveRestParameter(signature) && getParameterCount(signature) < targetParameterCount; + } + + function getContextualSignatureForFunctionLikeDeclaration(node: FunctionLikeDeclaration): Signature | undefined { + // Only function expressions, arrow functions, and object literal methods are contextually typed. + return isFunctionExpressionOrArrowFunction(node) || isObjectLiteralMethod(node) + ? getContextualSignature(node as FunctionExpression) + : undefined; + } + + // Return the contextual signature for a given expression node. A contextual type provides a + // contextual signature if it has a single call signature and if that call signature is non-generic. + // If the contextual type is a union type, get the signature from each type possible and if they are + // all identical ignoring their return type, the result is same signature but with return type as + // union type of return types from these signatures + function getContextualSignature(node: FunctionExpression | ArrowFunction | MethodDeclaration): Signature | undefined { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + const typeTagSignature = getSignatureOfTypeTag(node); + if (typeTagSignature) { + return typeTagSignature; + } + const type = getApparentTypeOfContextualType(node, ContextFlags.Signature); + if (!type) { + return undefined; + } + if (!(type.flags & TypeFlags.Union)) { + return getContextualCallSignature(type, node); + } + let signatureList: Signature[] | undefined; + const types = (type as UnionType).types; + for (const current of types) { + const signature = getContextualCallSignature(current, node); + if (signature) { + if (!signatureList) { + // This signature will contribute to contextual union signature + signatureList = [signature]; + } + else if (!compareSignaturesIdentical(signatureList[0], signature, /*partialMatch*/ false, /*ignoreThisTypes*/ true, /*ignoreReturnTypes*/ true, compareTypesIdentical)) { + // Signatures aren't identical, do not use + return undefined; + } + else { + // Use this signature for contextual union signature + signatureList.push(signature); + } + } + } + // Result is union of signatures collected (return type is union of return types of this signature set) + if (signatureList) { + return signatureList.length === 1 ? signatureList[0] : createUnionSignature(signatureList[0], signatureList); + } + } + + function checkGrammarRegularExpressionLiteral(node: RegularExpressionLiteral) { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile) && !node.isUnterminated) { + let lastError: DiagnosticWithLocation | undefined; + scanner ??= createScanner(ScriptTarget.ESNext, /*skipTrivia*/ true); + scanner.setScriptTarget(sourceFile.languageVersion); + scanner.setLanguageVariant(sourceFile.languageVariant); + scanner.setOnError((message, length, arg0) => { + // For providing spelling suggestions + const start = scanner!.getTokenEnd(); + if (message.category === DiagnosticCategory.Message && lastError && start === lastError.start && length === lastError.length) { + const error = createDetachedDiagnostic(sourceFile.fileName, sourceFile.text, start, length, message, arg0); + addRelatedInfo(lastError, error); + } + else if (!lastError || start !== lastError.start) { + lastError = createFileDiagnostic(sourceFile, start, length, message, arg0); + diagnostics.add(lastError); + } + }); + scanner.setText(sourceFile.text, node.pos, node.end - node.pos); + try { + scanner.scan(); + Debug.assert(scanner.reScanSlashToken(/*reportErrors*/ true) === SyntaxKind.RegularExpressionLiteral, "Expected scanner to rescan RegularExpressionLiteral"); + return !!lastError; + } + finally { + scanner.setText(""); + scanner.setOnError(/*onError*/ undefined); + } + } + return false; + } + + function checkRegularExpressionLiteral(node: RegularExpressionLiteral) { + const nodeLinks = getNodeLinks(node); + if (!(nodeLinks.flags & NodeCheckFlags.TypeChecked)) { + nodeLinks.flags |= NodeCheckFlags.TypeChecked; + addLazyDiagnostic(() => checkGrammarRegularExpressionLiteral(node)); + } + return globalRegExpType; + } + + function checkSpreadExpression(node: SpreadElement, checkMode?: CheckMode): Type { + if (languageVersion < LanguageFeatureMinimumTarget.SpreadElements) { + checkExternalEmitHelpers(node, compilerOptions.downlevelIteration ? ExternalEmitHelpers.SpreadIncludes : ExternalEmitHelpers.SpreadArray); + } + + const arrayOrIterableType = checkExpression(node.expression, checkMode); + return checkIteratedTypeOrElementType(IterationUse.Spread, arrayOrIterableType, undefinedType, node.expression); + } + + function checkSyntheticExpression(node: SyntheticExpression): Type { + return node.isSpread ? getIndexedAccessType(node.type, numberType) : node.type; + } + + function hasDefaultValue(node: BindingElement | Expression): boolean { + return (node.kind === SyntaxKind.BindingElement && !!(node as BindingElement).initializer) || + (node.kind === SyntaxKind.BinaryExpression && (node as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken); + } + + function isSpreadIntoCallOrNew(node: ArrayLiteralExpression) { + const parent = walkUpParenthesizedExpressions(node.parent); + return isSpreadElement(parent) && isCallOrNewExpression(parent.parent); + } + + function checkArrayLiteral(node: ArrayLiteralExpression, checkMode: CheckMode | undefined, forceTuple: boolean | undefined): Type { + const elements = node.elements; + const elementCount = elements.length; + const elementTypes: Type[] = []; + const elementFlags: ElementFlags[] = []; + pushCachedContextualType(node); + const inDestructuringPattern = isAssignmentTarget(node); + const inConstContext = isConstContext(node); + const contextualType = getApparentTypeOfContextualType(node, /*contextFlags*/ undefined); + const inTupleContext = isSpreadIntoCallOrNew(node) || !!contextualType && someType(contextualType, t => isTupleLikeType(t) || isGenericMappedType(t) && !t.nameType && !!getHomomorphicTypeVariable(t.target as MappedType || t)); + + let hasOmittedExpression = false; + for (let i = 0; i < elementCount; i++) { + const e = elements[i]; + if (e.kind === SyntaxKind.SpreadElement) { + if (languageVersion < LanguageFeatureMinimumTarget.SpreadElements) { + checkExternalEmitHelpers(e, compilerOptions.downlevelIteration ? ExternalEmitHelpers.SpreadIncludes : ExternalEmitHelpers.SpreadArray); + } + const spreadType = checkExpression((e as SpreadElement).expression, checkMode, forceTuple); + if (isArrayLikeType(spreadType)) { + elementTypes.push(spreadType); + elementFlags.push(ElementFlags.Variadic); + } + else if (inDestructuringPattern) { + // Given the following situation: + // var c: {}; + // [...c] = ["", 0]; + // + // c is represented in the tree as a spread element in an array literal. + // But c really functions as a rest element, and its purpose is to provide + // a contextual type for the right hand side of the assignment. Therefore, + // instead of calling checkExpression on "...c", which will give an error + // if c is not iterable/array-like, we need to act as if we are trying to + // get the contextual element type from it. So we do something similar to + // getContextualTypeForElementExpression, which will crucially not error + // if there is no index type / iterated type. + const restElementType = getIndexTypeOfType(spreadType, numberType) || + getIteratedTypeOrElementType(IterationUse.Destructuring, spreadType, undefinedType, /*errorNode*/ undefined, /*checkAssignability*/ false) || + unknownType; + elementTypes.push(restElementType); + elementFlags.push(ElementFlags.Rest); + } + else { + elementTypes.push(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, (e as SpreadElement).expression)); + elementFlags.push(ElementFlags.Rest); + } + } + else if (exactOptionalPropertyTypes && e.kind === SyntaxKind.OmittedExpression) { + hasOmittedExpression = true; + elementTypes.push(undefinedOrMissingType); + elementFlags.push(ElementFlags.Optional); + } + else { + const type = checkExpressionForMutableLocation(e, checkMode, forceTuple); + elementTypes.push(addOptionality(type, /*isProperty*/ true, hasOmittedExpression)); + elementFlags.push(hasOmittedExpression ? ElementFlags.Optional : ElementFlags.Required); + if (inTupleContext && checkMode && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && isContextSensitive(e)) { + const inferenceContext = getInferenceContext(node); + Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context + addIntraExpressionInferenceSite(inferenceContext, e, type); + } + } + } + popContextualType(); + if (inDestructuringPattern) { + return createTupleType(elementTypes, elementFlags); + } + if (forceTuple || inConstContext || inTupleContext) { + return createArrayLiteralType(createTupleType(elementTypes, elementFlags, /*readonly*/ inConstContext && !(contextualType && someType(contextualType, isMutableArrayLikeType)))); + } + return createArrayLiteralType(createArrayType( + elementTypes.length ? + getUnionType(sameMap(elementTypes, (t, i) => elementFlags[i] & ElementFlags.Variadic ? getIndexedAccessTypeOrUndefined(t, numberType) || anyType : t), UnionReduction.Subtype) : + strictNullChecks ? implicitNeverType : undefinedWideningType, + inConstContext, + )); + } + + function createArrayLiteralType(type: Type) { + if (!(getObjectFlags(type) & ObjectFlags.Reference)) { + return type; + } + let literalType = (type as TypeReference).literalType; + if (!literalType) { + literalType = (type as TypeReference).literalType = cloneTypeReference(type as TypeReference); + literalType.objectFlags |= ObjectFlags.ArrayLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + } + return literalType; + } + + function isNumericName(name: DeclarationName): boolean { + switch (name.kind) { + case SyntaxKind.ComputedPropertyName: + return isNumericComputedName(name); + case SyntaxKind.Identifier: + return isNumericLiteralName(name.escapedText); + case SyntaxKind.NumericLiteral: + case SyntaxKind.StringLiteral: + return isNumericLiteralName(name.text); + default: + return false; + } + } + + function isNumericComputedName(name: ComputedPropertyName): boolean { + // It seems odd to consider an expression of type Any to result in a numeric name, + // but this behavior is consistent with checkIndexedAccess + return isTypeAssignableToKind(checkComputedPropertyName(name), TypeFlags.NumberLike); + } + + function checkComputedPropertyName(node: ComputedPropertyName): Type { + const links = getNodeLinks(node.expression); + if (!links.resolvedType) { + if ( + (isTypeLiteralNode(node.parent.parent) || isClassLike(node.parent.parent) || isInterfaceDeclaration(node.parent.parent)) + && isBinaryExpression(node.expression) && node.expression.operatorToken.kind === SyntaxKind.InKeyword + && node.parent.kind !== SyntaxKind.GetAccessor && node.parent.kind !== SyntaxKind.SetAccessor + ) { + return links.resolvedType = errorType; + } + links.resolvedType = checkExpression(node.expression); + // The computed property name of a non-static class field within a loop must be stored in a block-scoped binding. + // (It needs to be bound at class evaluation time.) + if (isPropertyDeclaration(node.parent) && !hasStaticModifier(node.parent) && isClassExpression(node.parent.parent)) { + const container = getEnclosingBlockScopeContainer(node.parent.parent); + const enclosingIterationStatement = getEnclosingIterationStatement(container); + if (enclosingIterationStatement) { + // The computed field name will use a block scoped binding which can be unique for each iteration of the loop. + getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; + // The generated variable which stores the computed field name must be block-scoped. + getNodeLinks(node).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + // The generated variable which stores the class must be block-scoped. + getNodeLinks(node.parent.parent).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + } + } + // This will allow types number, string, symbol or any. It will also allow enums, the unknown + // type, and any union of these types (like string | number). + if ( + links.resolvedType.flags & TypeFlags.Nullable || + !isTypeAssignableToKind(links.resolvedType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike) && + !isTypeAssignableTo(links.resolvedType, stringNumberSymbolType) + ) { + error(node, Diagnostics.A_computed_property_name_must_be_of_type_string_number_symbol_or_any); + } + } + + return links.resolvedType; + } + + function isSymbolWithNumericName(symbol: Symbol) { + const firstDecl = symbol.declarations?.[0]; + return isNumericLiteralName(symbol.escapedName) || (firstDecl && isNamedDeclaration(firstDecl) && isNumericName(firstDecl.name)); + } + + function isSymbolWithSymbolName(symbol: Symbol) { + const firstDecl = symbol.declarations?.[0]; + return isKnownSymbol(symbol) || (firstDecl && isNamedDeclaration(firstDecl) && isComputedPropertyName(firstDecl.name) && + isTypeAssignableToKind(checkComputedPropertyName(firstDecl.name), TypeFlags.ESSymbol)); + } + + function getObjectLiteralIndexInfo(node: ObjectLiteralExpression, offset: number, properties: Symbol[], keyType: Type): IndexInfo { + const propTypes: Type[] = []; + for (let i = offset; i < properties.length; i++) { + const prop = properties[i]; + if ( + keyType === stringType && !isSymbolWithSymbolName(prop) || + keyType === numberType && isSymbolWithNumericName(prop) || + keyType === esSymbolType && isSymbolWithSymbolName(prop) + ) { + propTypes.push(getTypeOfSymbol(properties[i])); + } + } + const unionType = propTypes.length ? getUnionType(propTypes, UnionReduction.Subtype) : undefinedType; + return createIndexInfo(keyType, unionType, isConstContext(node)); + } + + function getImmediateAliasedSymbol(symbol: Symbol): Symbol | undefined { + Debug.assert((symbol.flags & SymbolFlags.Alias) !== 0, "Should only get Alias here."); + const links = getSymbolLinks(symbol); + if (!links.immediateTarget) { + const node = getDeclarationOfAliasSymbol(symbol); + if (!node) return Debug.fail(); + links.immediateTarget = getTargetOfAliasDeclaration(node, /*dontRecursivelyResolve*/ true); + } + + return links.immediateTarget; + } + + function checkObjectLiteral(node: ObjectLiteralExpression, checkMode: CheckMode = CheckMode.Normal): Type { + const inDestructuringPattern = isAssignmentTarget(node); + // Grammar checking + checkGrammarObjectLiteralExpression(node, inDestructuringPattern); + + const allPropertiesTable = strictNullChecks ? createSymbolTable() : undefined; + let propertiesTable = createSymbolTable(); + let propertiesArray: Symbol[] = []; + let spread: Type = emptyObjectType; + + pushCachedContextualType(node); + const contextualType = getApparentTypeOfContextualType(node, /*contextFlags*/ undefined); + const contextualTypeHasPattern = contextualType && contextualType.pattern && + (contextualType.pattern.kind === SyntaxKind.ObjectBindingPattern || contextualType.pattern.kind === SyntaxKind.ObjectLiteralExpression); + const inConstContext = isConstContext(node); + const checkFlags = inConstContext ? CheckFlags.Readonly : 0; + const isInJavascript = isInJSFile(node) && !isInJsonFile(node); + const enumTag = isInJavascript ? getJSDocEnumTag(node) : undefined; + const isJSObjectLiteral = !contextualType && isInJavascript && !enumTag; + let objectFlags: ObjectFlags = ObjectFlags.FreshLiteral; + let patternWithComputedProperties = false; + let hasComputedStringProperty = false; + let hasComputedNumberProperty = false; + let hasComputedSymbolProperty = false; + + // Spreads may cause an early bail; ensure computed names are always checked (this is cached) + // As otherwise they may not be checked until exports for the type at this position are retrieved, + // which may never occur. + for (const elem of node.properties) { + if (elem.name && isComputedPropertyName(elem.name)) { + checkComputedPropertyName(elem.name); + } + } + + let offset = 0; + for (const memberDecl of node.properties) { + let member = getSymbolOfDeclaration(memberDecl); + const computedNameType = memberDecl.name && memberDecl.name.kind === SyntaxKind.ComputedPropertyName ? + checkComputedPropertyName(memberDecl.name) : undefined; + if ( + memberDecl.kind === SyntaxKind.PropertyAssignment || + memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment || + isObjectLiteralMethod(memberDecl) + ) { + let type = memberDecl.kind === SyntaxKind.PropertyAssignment ? checkPropertyAssignment(memberDecl, checkMode) : + // avoid resolving the left side of the ShorthandPropertyAssignment outside of the destructuring + // for error recovery purposes. For example, if a user wrote `{ a = 100 }` instead of `{ a: 100 }`. + // we don't want to say "could not find 'a'". + memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment ? checkExpressionForMutableLocation(!inDestructuringPattern && memberDecl.objectAssignmentInitializer ? memberDecl.objectAssignmentInitializer : memberDecl.name, checkMode) : + checkObjectLiteralMethod(memberDecl, checkMode); + if (isInJavascript) { + const jsDocType = getTypeForDeclarationFromJSDocComment(memberDecl); + if (jsDocType) { + checkTypeAssignableTo(type, jsDocType, memberDecl); + type = jsDocType; + } + else if (enumTag && enumTag.typeExpression) { + checkTypeAssignableTo(type, getTypeFromTypeNode(enumTag.typeExpression), memberDecl); + } + } + objectFlags |= getObjectFlags(type) & ObjectFlags.PropagatingFlags; + const nameType = computedNameType && isTypeUsableAsPropertyName(computedNameType) ? computedNameType : undefined; + const prop = nameType ? + createSymbol(SymbolFlags.Property | member.flags, getPropertyNameFromType(nameType), checkFlags | CheckFlags.Late) : + createSymbol(SymbolFlags.Property | member.flags, member.escapedName, checkFlags); + if (nameType) { + prop.links.nameType = nameType; + } + + if (inDestructuringPattern) { + // If object literal is an assignment pattern and if the assignment pattern specifies a default value + // for the property, make the property optional. + const isOptional = (memberDecl.kind === SyntaxKind.PropertyAssignment && hasDefaultValue(memberDecl.initializer)) || + (memberDecl.kind === SyntaxKind.ShorthandPropertyAssignment && memberDecl.objectAssignmentInitializer); + if (isOptional) { + prop.flags |= SymbolFlags.Optional; + } + } + else if (contextualTypeHasPattern && !(getObjectFlags(contextualType) & ObjectFlags.ObjectLiteralPatternWithComputedProperties)) { + // If object literal is contextually typed by the implied type of a binding pattern, and if the + // binding pattern specifies a default value for the property, make the property optional. + const impliedProp = getPropertyOfType(contextualType, member.escapedName); + if (impliedProp) { + prop.flags |= impliedProp.flags & SymbolFlags.Optional; + } + else if (!getIndexInfoOfType(contextualType, stringType)) { + error(memberDecl.name, Diagnostics.Object_literal_may_only_specify_known_properties_and_0_does_not_exist_in_type_1, symbolToString(member), typeToString(contextualType)); + } + } + + prop.declarations = member.declarations; + prop.parent = member.parent; + if (member.valueDeclaration) { + prop.valueDeclaration = member.valueDeclaration; + } + + prop.links.type = type; + prop.links.target = member; + member = prop; + allPropertiesTable?.set(prop.escapedName, prop); + + if ( + contextualType && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && + (memberDecl.kind === SyntaxKind.PropertyAssignment || memberDecl.kind === SyntaxKind.MethodDeclaration) && isContextSensitive(memberDecl) + ) { + const inferenceContext = getInferenceContext(node); + Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context + const inferenceNode = memberDecl.kind === SyntaxKind.PropertyAssignment ? memberDecl.initializer : memberDecl; + addIntraExpressionInferenceSite(inferenceContext, inferenceNode, type); + } + } + else if (memberDecl.kind === SyntaxKind.SpreadAssignment) { + if (languageVersion < LanguageFeatureMinimumTarget.ObjectAssign) { + checkExternalEmitHelpers(memberDecl, ExternalEmitHelpers.Assign); + } + if (propertiesArray.length > 0) { + spread = getSpreadType(spread, createObjectLiteralType(), node.symbol, objectFlags, inConstContext); + propertiesArray = []; + propertiesTable = createSymbolTable(); + hasComputedStringProperty = false; + hasComputedNumberProperty = false; + hasComputedSymbolProperty = false; + } + const type = getReducedType(checkExpression(memberDecl.expression, checkMode & CheckMode.Inferential)); + if (isValidSpreadType(type)) { + const mergedType = tryMergeUnionOfObjectTypeAndEmptyObject(type, inConstContext); + if (allPropertiesTable) { + checkSpreadPropOverrides(mergedType, allPropertiesTable, memberDecl); + } + offset = propertiesArray.length; + if (isErrorType(spread)) { + continue; + } + spread = getSpreadType(spread, mergedType, node.symbol, objectFlags, inConstContext); + } + else { + error(memberDecl, Diagnostics.Spread_types_may_only_be_created_from_object_types); + spread = errorType; + } + continue; + } + else { + // TypeScript 1.0 spec (April 2014) + // A get accessor declaration is processed in the same manner as + // an ordinary function declaration(section 6.1) with no parameters. + // A set accessor declaration is processed in the same manner + // as an ordinary function declaration with a single parameter and a Void return type. + Debug.assert(memberDecl.kind === SyntaxKind.GetAccessor || memberDecl.kind === SyntaxKind.SetAccessor); + checkNodeDeferred(memberDecl); + } + + if (computedNameType && !(computedNameType.flags & TypeFlags.StringOrNumberLiteralOrUnique)) { + if (isTypeAssignableTo(computedNameType, stringNumberSymbolType)) { + if (isTypeAssignableTo(computedNameType, numberType)) { + hasComputedNumberProperty = true; + } + else if (isTypeAssignableTo(computedNameType, esSymbolType)) { + hasComputedSymbolProperty = true; + } + else { + hasComputedStringProperty = true; + } + if (inDestructuringPattern) { + patternWithComputedProperties = true; + } + } + } + else { + propertiesTable.set(member.escapedName, member); + } + propertiesArray.push(member); + } + popContextualType(); + + // If object literal is contextually typed by the implied type of a binding pattern, augment the result + // type with those properties for which the binding pattern specifies a default value. + // If the object literal is spread into another object literal, skip this step and let the top-level object + // literal handle it instead. Note that this might require full traversal to the root pattern's parent + // as it's the guaranteed to be the common ancestor of the pattern node and the current object node. + // It's not possible to check if the immediate parent node is a spread assignment + // since the type flows in non-obvious ways through conditional expressions, IIFEs and more. + if (contextualTypeHasPattern) { + const rootPatternParent = findAncestor(contextualType.pattern!.parent, n => + n.kind === SyntaxKind.VariableDeclaration || + n.kind === SyntaxKind.BinaryExpression || + n.kind === SyntaxKind.Parameter); + const spreadOrOutsideRootObject = findAncestor(node, n => + n === rootPatternParent || + n.kind === SyntaxKind.SpreadAssignment)!; + + if (spreadOrOutsideRootObject.kind !== SyntaxKind.SpreadAssignment) { + for (const prop of getPropertiesOfType(contextualType)) { + if (!propertiesTable.get(prop.escapedName) && !getPropertyOfType(spread, prop.escapedName)) { + if (!(prop.flags & SymbolFlags.Optional)) { + error(prop.valueDeclaration || tryCast(prop, isTransientSymbol)?.links.bindingElement, Diagnostics.Initializer_provides_no_value_for_this_binding_element_and_the_binding_element_has_no_default_value); + } + propertiesTable.set(prop.escapedName, prop); + propertiesArray.push(prop); + } + } + } + } + + if (isErrorType(spread)) { + return errorType; + } + + if (spread !== emptyObjectType) { + if (propertiesArray.length > 0) { + spread = getSpreadType(spread, createObjectLiteralType(), node.symbol, objectFlags, inConstContext); + propertiesArray = []; + propertiesTable = createSymbolTable(); + hasComputedStringProperty = false; + hasComputedNumberProperty = false; + } + // remap the raw emptyObjectType fed in at the top into a fresh empty object literal type, unique to this use site + return mapType(spread, t => t === emptyObjectType ? createObjectLiteralType() : t); + } + + return createObjectLiteralType(); + + function createObjectLiteralType() { + const indexInfos = []; + if (hasComputedStringProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, stringType)); + if (hasComputedNumberProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, numberType)); + if (hasComputedSymbolProperty) indexInfos.push(getObjectLiteralIndexInfo(node, offset, propertiesArray, esSymbolType)); + const result = createAnonymousType(node.symbol, propertiesTable, emptyArray, emptyArray, indexInfos); + result.objectFlags |= objectFlags | ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + if (isJSObjectLiteral) { + result.objectFlags |= ObjectFlags.JSLiteral; + } + if (patternWithComputedProperties) { + result.objectFlags |= ObjectFlags.ObjectLiteralPatternWithComputedProperties; + } + if (inDestructuringPattern) { + result.pattern = node; + } + return result; + } + } + + function isValidSpreadType(type: Type): boolean { + const t = removeDefinitelyFalsyTypes(mapType(type, getBaseConstraintOrType)); + return !!(t.flags & (TypeFlags.Any | TypeFlags.NonPrimitive | TypeFlags.Object | TypeFlags.InstantiableNonPrimitive) || + t.flags & TypeFlags.UnionOrIntersection && every((t as UnionOrIntersectionType).types, isValidSpreadType)); + } + + function checkJsxSelfClosingElementDeferred(node: JsxSelfClosingElement) { + checkJsxOpeningLikeElementOrOpeningFragment(node); + } + + function checkJsxSelfClosingElement(node: JsxSelfClosingElement, _checkMode: CheckMode | undefined): Type { + checkNodeDeferred(node); + return getJsxElementTypeAt(node) || anyType; + } + + function checkJsxElementDeferred(node: JsxElement) { + // Check attributes + checkJsxOpeningLikeElementOrOpeningFragment(node.openingElement); + + // Perform resolution on the closing tag so that rename/go to definition/etc work + if (isJsxIntrinsicTagName(node.closingElement.tagName)) { + getIntrinsicTagSymbol(node.closingElement); + } + else { + checkExpression(node.closingElement.tagName); + } + + checkJsxChildren(node); + } + + function checkJsxElement(node: JsxElement, _checkMode: CheckMode | undefined): Type { + checkNodeDeferred(node); + + return getJsxElementTypeAt(node) || anyType; + } + + function checkJsxFragment(node: JsxFragment): Type { + checkJsxOpeningLikeElementOrOpeningFragment(node.openingFragment); + + // by default, jsx:'react' will use jsxFactory = React.createElement and jsxFragmentFactory = React.Fragment + // if jsxFactory compiler option is provided, ensure jsxFragmentFactory compiler option or @jsxFrag pragma is provided too + const nodeSourceFile = getSourceFileOfNode(node); + if ( + getJSXTransformEnabled(compilerOptions) && (compilerOptions.jsxFactory || nodeSourceFile.pragmas.has("jsx")) + && !compilerOptions.jsxFragmentFactory && !nodeSourceFile.pragmas.has("jsxfrag") + ) { + error( + node, + compilerOptions.jsxFactory + ? Diagnostics.The_jsxFragmentFactory_compiler_option_must_be_provided_to_use_JSX_fragments_with_the_jsxFactory_compiler_option + : Diagnostics.An_jsxFrag_pragma_is_required_when_using_an_jsx_pragma_with_JSX_fragments, + ); + } + + checkJsxChildren(node); + return getJsxElementTypeAt(node) || anyType; + } + + function isHyphenatedJsxName(name: string | __String) { + return (name as string).includes("-"); + } + + /** + * Returns true iff React would emit this tag name as a string rather than an identifier or qualified name + */ + function isJsxIntrinsicTagName(tagName: Node): tagName is Identifier | JsxNamespacedName { + return isIdentifier(tagName) && isIntrinsicJsxName(tagName.escapedText) || isJsxNamespacedName(tagName); + } + + function checkJsxAttribute(node: JsxAttribute, checkMode?: CheckMode) { + return node.initializer + ? checkExpressionForMutableLocation(node.initializer, checkMode) + : trueType; // is sugar for + } + + /** + * Get attributes type of the JSX opening-like element. The result is from resolving "attributes" property of the opening-like element. + * + * @param openingLikeElement a JSX opening-like element + * @param filter a function to remove attributes that will not participate in checking whether attributes are assignable + * @return an anonymous type (similar to the one returned by checkObjectLiteral) in which its properties are attributes property. + * @remarks Because this function calls getSpreadType, it needs to use the same checks as checkObjectLiteral, + * which also calls getSpreadType. + */ + function createJsxAttributesTypeFromAttributesProperty(openingLikeElement: JsxOpeningLikeElement, checkMode: CheckMode = CheckMode.Normal) { + const attributes = openingLikeElement.attributes; + const contextualType = getContextualType(attributes, ContextFlags.None); + const allAttributesTable = strictNullChecks ? createSymbolTable() : undefined; + let attributesTable = createSymbolTable(); + let spread: Type = emptyJsxObjectType; + let hasSpreadAnyType = false; + let typeToIntersect: Type | undefined; + let explicitlySpecifyChildrenAttribute = false; + let objectFlags: ObjectFlags = ObjectFlags.JsxAttributes; + const jsxChildrenPropertyName = getJsxElementChildrenPropertyName(getJsxNamespaceAt(openingLikeElement)); + + for (const attributeDecl of attributes.properties) { + const member = attributeDecl.symbol; + if (isJsxAttribute(attributeDecl)) { + const exprType = checkJsxAttribute(attributeDecl, checkMode); + objectFlags |= getObjectFlags(exprType) & ObjectFlags.PropagatingFlags; + + const attributeSymbol = createSymbol(SymbolFlags.Property | member.flags, member.escapedName); + attributeSymbol.declarations = member.declarations; + attributeSymbol.parent = member.parent; + if (member.valueDeclaration) { + attributeSymbol.valueDeclaration = member.valueDeclaration; + } + attributeSymbol.links.type = exprType; + attributeSymbol.links.target = member; + attributesTable.set(attributeSymbol.escapedName, attributeSymbol); + allAttributesTable?.set(attributeSymbol.escapedName, attributeSymbol); + if (getEscapedTextOfJsxAttributeName(attributeDecl.name) === jsxChildrenPropertyName) { + explicitlySpecifyChildrenAttribute = true; + } + if (contextualType) { + const prop = getPropertyOfType(contextualType, member.escapedName); + if (prop && prop.declarations && isDeprecatedSymbol(prop) && isIdentifier(attributeDecl.name)) { + addDeprecatedSuggestion(attributeDecl.name, prop.declarations, attributeDecl.name.escapedText as string); + } + } + if (contextualType && checkMode & CheckMode.Inferential && !(checkMode & CheckMode.SkipContextSensitive) && isContextSensitive(attributeDecl)) { + const inferenceContext = getInferenceContext(attributes); + Debug.assert(inferenceContext); // In CheckMode.Inferential we should always have an inference context + const inferenceNode = (attributeDecl.initializer as JsxExpression).expression!; + addIntraExpressionInferenceSite(inferenceContext, inferenceNode, exprType); + } + } + else { + Debug.assert(attributeDecl.kind === SyntaxKind.JsxSpreadAttribute); + if (attributesTable.size > 0) { + spread = getSpreadType(spread, createJsxAttributesType(), attributes.symbol, objectFlags, /*readonly*/ false); + attributesTable = createSymbolTable(); + } + const exprType = getReducedType(checkExpression(attributeDecl.expression, checkMode & CheckMode.Inferential)); + if (isTypeAny(exprType)) { + hasSpreadAnyType = true; + } + if (isValidSpreadType(exprType)) { + spread = getSpreadType(spread, exprType, attributes.symbol, objectFlags, /*readonly*/ false); + if (allAttributesTable) { + checkSpreadPropOverrides(exprType, allAttributesTable, attributeDecl); + } + } + else { + error(attributeDecl.expression, Diagnostics.Spread_types_may_only_be_created_from_object_types); + typeToIntersect = typeToIntersect ? getIntersectionType([typeToIntersect, exprType]) : exprType; + } + } + } + + if (!hasSpreadAnyType) { + if (attributesTable.size > 0) { + spread = getSpreadType(spread, createJsxAttributesType(), attributes.symbol, objectFlags, /*readonly*/ false); + } + } + + // Handle children attribute + const parent = openingLikeElement.parent.kind === SyntaxKind.JsxElement ? openingLikeElement.parent as JsxElement : undefined; + // We have to check that openingElement of the parent is the one we are visiting as this may not be true for selfClosingElement + if (parent && parent.openingElement === openingLikeElement && getSemanticJsxChildren(parent.children).length > 0) { + const childrenTypes: Type[] = checkJsxChildren(parent, checkMode); + + if (!hasSpreadAnyType && jsxChildrenPropertyName && jsxChildrenPropertyName !== "") { + // Error if there is a attribute named "children" explicitly specified and children element. + // This is because children element will overwrite the value from attributes. + // Note: we will not warn "children" attribute overwritten if "children" attribute is specified in object spread. + if (explicitlySpecifyChildrenAttribute) { + error(attributes, Diagnostics._0_are_specified_twice_The_attribute_named_0_will_be_overwritten, unescapeLeadingUnderscores(jsxChildrenPropertyName)); + } + + const contextualType = getApparentTypeOfContextualType(openingLikeElement.attributes, /*contextFlags*/ undefined); + const childrenContextualType = contextualType && getTypeOfPropertyOfContextualType(contextualType, jsxChildrenPropertyName); + // If there are children in the body of JSX element, create dummy attribute "children" with the union of children types so that it will pass the attribute checking process + const childrenPropSymbol = createSymbol(SymbolFlags.Property, jsxChildrenPropertyName); + childrenPropSymbol.links.type = childrenTypes.length === 1 ? childrenTypes[0] : + childrenContextualType && someType(childrenContextualType, isTupleLikeType) ? createTupleType(childrenTypes) : + createArrayType(getUnionType(childrenTypes)); + // Fake up a property declaration for the children + childrenPropSymbol.valueDeclaration = factory.createPropertySignature(/*modifiers*/ undefined, unescapeLeadingUnderscores(jsxChildrenPropertyName), /*questionToken*/ undefined, /*type*/ undefined); + setParent(childrenPropSymbol.valueDeclaration, attributes); + childrenPropSymbol.valueDeclaration.symbol = childrenPropSymbol; + const childPropMap = createSymbolTable(); + childPropMap.set(jsxChildrenPropertyName, childrenPropSymbol); + spread = getSpreadType(spread, createAnonymousType(attributes.symbol, childPropMap, emptyArray, emptyArray, emptyArray), attributes.symbol, objectFlags, /*readonly*/ false); + } + } + + if (hasSpreadAnyType) { + return anyType; + } + if (typeToIntersect && spread !== emptyJsxObjectType) { + return getIntersectionType([typeToIntersect, spread]); + } + return typeToIntersect || (spread === emptyJsxObjectType ? createJsxAttributesType() : spread); + + /** + * Create anonymous type from given attributes symbol table. + * @param symbol a symbol of JsxAttributes containing attributes corresponding to attributesTable + * @param attributesTable a symbol table of attributes property + */ + function createJsxAttributesType() { + objectFlags |= ObjectFlags.FreshLiteral; + const result = createAnonymousType(attributes.symbol, attributesTable, emptyArray, emptyArray, emptyArray); + result.objectFlags |= objectFlags | ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + return result; + } + } + + function checkJsxChildren(node: JsxElement | JsxFragment, checkMode?: CheckMode) { + const childrenTypes: Type[] = []; + for (const child of node.children) { + // In React, JSX text that contains only whitespaces will be ignored so we don't want to type-check that + // because then type of children property will have constituent of string type. + if (child.kind === SyntaxKind.JsxText) { + if (!child.containsOnlyTriviaWhiteSpaces) { + childrenTypes.push(stringType); + } + } + else if (child.kind === SyntaxKind.JsxExpression && !child.expression) { + continue; // empty jsx expressions don't *really* count as present children + } + else { + childrenTypes.push(checkExpressionForMutableLocation(child, checkMode)); + } + } + return childrenTypes; + } + + function checkSpreadPropOverrides(type: Type, props: SymbolTable, spread: SpreadAssignment | JsxSpreadAttribute) { + for (const right of getPropertiesOfType(type)) { + if (!(right.flags & SymbolFlags.Optional)) { + const left = props.get(right.escapedName); + if (left) { + const diagnostic = error(left.valueDeclaration, Diagnostics._0_is_specified_more_than_once_so_this_usage_will_be_overwritten, unescapeLeadingUnderscores(left.escapedName)); + addRelatedInfo(diagnostic, createDiagnosticForNode(spread, Diagnostics.This_spread_always_overwrites_this_property)); + } + } + } + } + + /** + * Check attributes property of opening-like element. This function is called during chooseOverload to get call signature of a JSX opening-like element. + * (See "checkApplicableSignatureForJsxOpeningLikeElement" for how the function is used) + * @param node a JSXAttributes to be resolved of its type + */ + function checkJsxAttributes(node: JsxAttributes, checkMode: CheckMode | undefined) { + return createJsxAttributesTypeFromAttributesProperty(node.parent, checkMode); + } + + function getJsxType(name: __String, location: Node | undefined) { + const namespace = getJsxNamespaceAt(location); + const exports = namespace && getExportsOfSymbol(namespace); + const typeSymbol = exports && getSymbol(exports, name, SymbolFlags.Type); + return typeSymbol ? getDeclaredTypeOfSymbol(typeSymbol) : errorType; + } + + /** + * Looks up an intrinsic tag name and returns a symbol that either points to an intrinsic + * property (in which case nodeLinks.jsxFlags will be IntrinsicNamedElement) or an intrinsic + * string index signature (in which case nodeLinks.jsxFlags will be IntrinsicIndexedElement). + * May also return unknownSymbol if both of these lookups fail. + */ + function getIntrinsicTagSymbol(node: JsxOpeningLikeElement | JsxClosingElement): Symbol { + const links = getNodeLinks(node); + if (!links.resolvedSymbol) { + const intrinsicElementsType = getJsxType(JsxNames.IntrinsicElements, node); + if (!isErrorType(intrinsicElementsType)) { + // Property case + if (!isIdentifier(node.tagName) && !isJsxNamespacedName(node.tagName)) return Debug.fail(); + const propName = isJsxNamespacedName(node.tagName) ? getEscapedTextOfJsxNamespacedName(node.tagName) : node.tagName.escapedText; + const intrinsicProp = getPropertyOfType(intrinsicElementsType, propName); + if (intrinsicProp) { + links.jsxFlags |= JsxFlags.IntrinsicNamedElement; + return links.resolvedSymbol = intrinsicProp; + } + + // Intrinsic string indexer case + const indexSymbol = getApplicableIndexSymbol(intrinsicElementsType, getStringLiteralType(unescapeLeadingUnderscores(propName))); + if (indexSymbol) { + links.jsxFlags |= JsxFlags.IntrinsicIndexedElement; + return links.resolvedSymbol = indexSymbol; + } + + if (getTypeOfPropertyOrIndexSignatureOfType(intrinsicElementsType, propName)) { + links.jsxFlags |= JsxFlags.IntrinsicIndexedElement; + return links.resolvedSymbol = intrinsicElementsType.symbol; + } + + // Wasn't found + error(node, Diagnostics.Property_0_does_not_exist_on_type_1, intrinsicTagNameToString(node.tagName), "JSX." + JsxNames.IntrinsicElements); + return links.resolvedSymbol = unknownSymbol; + } + else { + if (noImplicitAny) { + error(node, Diagnostics.JSX_element_implicitly_has_type_any_because_no_interface_JSX_0_exists, unescapeLeadingUnderscores(JsxNames.IntrinsicElements)); + } + return links.resolvedSymbol = unknownSymbol; + } + } + return links.resolvedSymbol; + } + + function getJsxNamespaceContainerForImplicitImport(location: Node | undefined): Symbol | undefined { + const file = location && getSourceFileOfNode(location); + const links = file && getNodeLinks(file); + if (links && links.jsxImplicitImportContainer === false) { + return undefined; + } + if (links && links.jsxImplicitImportContainer) { + return links.jsxImplicitImportContainer; + } + const runtimeImportSpecifier = getJSXRuntimeImport(getJSXImplicitImportBase(compilerOptions, file), compilerOptions); + if (!runtimeImportSpecifier) { + return undefined; + } + const isClassic = getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic; + const errorMessage = isClassic + ? Diagnostics.Cannot_find_module_0_Did_you_mean_to_set_the_moduleResolution_option_to_nodenext_or_to_add_aliases_to_the_paths_option + : Diagnostics.Cannot_find_module_0_or_its_corresponding_type_declarations; + const specifier = getJSXRuntimeImportSpecifier(file, runtimeImportSpecifier); + const mod = resolveExternalModule(specifier || location!, runtimeImportSpecifier, errorMessage, location!); + const result = mod && mod !== unknownSymbol ? getMergedSymbol(resolveSymbol(mod)) : undefined; + if (links) { + links.jsxImplicitImportContainer = result || false; + } + return result; + } + + function getJsxNamespaceAt(location: Node | undefined): Symbol { + const links = location && getNodeLinks(location); + if (links && links.jsxNamespace) { + return links.jsxNamespace; + } + if (!links || links.jsxNamespace !== false) { + let resolvedNamespace = getJsxNamespaceContainerForImplicitImport(location); + + if (!resolvedNamespace || resolvedNamespace === unknownSymbol) { + const namespaceName = getJsxNamespace(location); + resolvedNamespace = resolveName(location, namespaceName, SymbolFlags.Namespace, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + } + + if (resolvedNamespace) { + const candidate = resolveSymbol(getSymbol(getExportsOfSymbol(resolveSymbol(resolvedNamespace)), JsxNames.JSX, SymbolFlags.Namespace)); + if (candidate && candidate !== unknownSymbol) { + if (links) { + links.jsxNamespace = candidate; + } + return candidate; + } + } + if (links) { + links.jsxNamespace = false; + } + } + // JSX global fallback + const s = resolveSymbol(getGlobalSymbol(JsxNames.JSX, SymbolFlags.Namespace, /*diagnostic*/ undefined)); + if (s === unknownSymbol) { + return undefined!; // TODO: GH#18217 + } + return s!; // TODO: GH#18217 + } + + /** + * Look into JSX namespace and then look for container with matching name as nameOfAttribPropContainer. + * Get a single property from that container if existed. Report an error if there are more than one property. + * + * @param nameOfAttribPropContainer a string of value JsxNames.ElementAttributesPropertyNameContainer or JsxNames.ElementChildrenAttributeNameContainer + * if other string is given or the container doesn't exist, return undefined. + */ + function getNameFromJsxElementAttributesContainer(nameOfAttribPropContainer: __String, jsxNamespace: Symbol): __String | undefined { + // JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute [symbol] + const jsxElementAttribPropInterfaceSym = jsxNamespace && getSymbol(jsxNamespace.exports!, nameOfAttribPropContainer, SymbolFlags.Type); + // JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute [type] + const jsxElementAttribPropInterfaceType = jsxElementAttribPropInterfaceSym && getDeclaredTypeOfSymbol(jsxElementAttribPropInterfaceSym); + // The properties of JSX.ElementAttributesProperty | JSX.ElementChildrenAttribute + const propertiesOfJsxElementAttribPropInterface = jsxElementAttribPropInterfaceType && getPropertiesOfType(jsxElementAttribPropInterfaceType); + if (propertiesOfJsxElementAttribPropInterface) { + // Element Attributes has zero properties, so the element attributes type will be the class instance type + if (propertiesOfJsxElementAttribPropInterface.length === 0) { + return "" as __String; + } + // Element Attributes has one property, so the element attributes type will be the type of the corresponding + // property of the class instance type + else if (propertiesOfJsxElementAttribPropInterface.length === 1) { + return propertiesOfJsxElementAttribPropInterface[0].escapedName; + } + else if (propertiesOfJsxElementAttribPropInterface.length > 1 && jsxElementAttribPropInterfaceSym.declarations) { + // More than one property on ElementAttributesProperty is an error + error(jsxElementAttribPropInterfaceSym.declarations[0], Diagnostics.The_global_type_JSX_0_may_not_have_more_than_one_property, unescapeLeadingUnderscores(nameOfAttribPropContainer)); + } + } + return undefined; + } + + function getJsxLibraryManagedAttributes(jsxNamespace: Symbol) { + // JSX.LibraryManagedAttributes [symbol] + return jsxNamespace && getSymbol(jsxNamespace.exports!, JsxNames.LibraryManagedAttributes, SymbolFlags.Type); + } + + function getJsxElementTypeSymbol(jsxNamespace: Symbol) { + // JSX.ElementType [symbol] + return jsxNamespace && getSymbol(jsxNamespace.exports!, JsxNames.ElementType, SymbolFlags.Type); + } + + /// e.g. "props" for React.d.ts, + /// or 'undefined' if ElementAttributesProperty doesn't exist (which means all + /// non-intrinsic elements' attributes type is 'any'), + /// or '' if it has 0 properties (which means every + /// non-intrinsic elements' attributes type is the element instance type) + function getJsxElementPropertiesName(jsxNamespace: Symbol) { + return getNameFromJsxElementAttributesContainer(JsxNames.ElementAttributesPropertyNameContainer, jsxNamespace); + } + + function getJsxElementChildrenPropertyName(jsxNamespace: Symbol): __String | undefined { + return getNameFromJsxElementAttributesContainer(JsxNames.ElementChildrenAttributeNameContainer, jsxNamespace); + } + + function getUninstantiatedJsxSignaturesOfType(elementType: Type, caller: JsxOpeningLikeElement): readonly Signature[] { + if (elementType.flags & TypeFlags.String) { + return [anySignature]; + } + else if (elementType.flags & TypeFlags.StringLiteral) { + const intrinsicType = getIntrinsicAttributesTypeFromStringLiteralType(elementType as StringLiteralType, caller); + if (!intrinsicType) { + error(caller, Diagnostics.Property_0_does_not_exist_on_type_1, (elementType as StringLiteralType).value, "JSX." + JsxNames.IntrinsicElements); + return emptyArray; + } + else { + const fakeSignature = createSignatureForJSXIntrinsic(caller, intrinsicType); + return [fakeSignature]; + } + } + const apparentElemType = getApparentType(elementType); + // Resolve the signatures, preferring constructor + let signatures = getSignaturesOfType(apparentElemType, SignatureKind.Construct); + if (signatures.length === 0) { + // No construct signatures, try call signatures + signatures = getSignaturesOfType(apparentElemType, SignatureKind.Call); + } + if (signatures.length === 0 && apparentElemType.flags & TypeFlags.Union) { + // If each member has some combination of new/call signatures; make a union signature list for those + signatures = getUnionSignatures(map((apparentElemType as UnionType).types, t => getUninstantiatedJsxSignaturesOfType(t, caller))); + } + return signatures; + } + + function getIntrinsicAttributesTypeFromStringLiteralType(type: StringLiteralType, location: Node): Type | undefined { + // If the elemType is a stringLiteral type, we can then provide a check to make sure that the string literal type is one of the Jsx intrinsic element type + // For example: + // var CustomTag: "h1" = "h1"; + // Hello World + const intrinsicElementsType = getJsxType(JsxNames.IntrinsicElements, location); + if (!isErrorType(intrinsicElementsType)) { + const stringLiteralTypeName = type.value; + const intrinsicProp = getPropertyOfType(intrinsicElementsType, escapeLeadingUnderscores(stringLiteralTypeName)); + if (intrinsicProp) { + return getTypeOfSymbol(intrinsicProp); + } + const indexSignatureType = getIndexTypeOfType(intrinsicElementsType, stringType); + if (indexSignatureType) { + return indexSignatureType; + } + return undefined; + } + // If we need to report an error, we already done so here. So just return any to prevent any more error downstream + return anyType; + } + + function checkJsxReturnAssignableToAppropriateBound(refKind: JsxReferenceKind, elemInstanceType: Type, openingLikeElement: JsxOpeningLikeElement) { + if (refKind === JsxReferenceKind.Function) { + const sfcReturnConstraint = getJsxStatelessElementTypeAt(openingLikeElement); + if (sfcReturnConstraint) { + checkTypeRelatedTo(elemInstanceType, sfcReturnConstraint, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_return_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); + } + } + else if (refKind === JsxReferenceKind.Component) { + const classConstraint = getJsxElementClassTypeAt(openingLikeElement); + if (classConstraint) { + // Issue an error if this return type isn't assignable to JSX.ElementClass, failing that + checkTypeRelatedTo(elemInstanceType, classConstraint, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_instance_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); + } + } + else { // Mixed + const sfcReturnConstraint = getJsxStatelessElementTypeAt(openingLikeElement); + const classConstraint = getJsxElementClassTypeAt(openingLikeElement); + if (!sfcReturnConstraint || !classConstraint) { + return; + } + const combined = getUnionType([sfcReturnConstraint, classConstraint]); + checkTypeRelatedTo(elemInstanceType, combined, assignableRelation, openingLikeElement.tagName, Diagnostics.Its_element_type_0_is_not_a_valid_JSX_element, generateInitialErrorChain); + } + + function generateInitialErrorChain(): DiagnosticMessageChain { + const componentName = getTextOfNode(openingLikeElement.tagName); + return chainDiagnosticMessages(/*details*/ undefined, Diagnostics._0_cannot_be_used_as_a_JSX_component, componentName); + } + } + + /** + * Get attributes type of the given intrinsic opening-like Jsx element by resolving the tag name. + * The function is intended to be called from a function which has checked that the opening element is an intrinsic element. + * @param node an intrinsic JSX opening-like element + */ + function getIntrinsicAttributesTypeFromJsxOpeningLikeElement(node: JsxOpeningLikeElement): Type { + Debug.assert(isJsxIntrinsicTagName(node.tagName)); + const links = getNodeLinks(node); + if (!links.resolvedJsxElementAttributesType) { + const symbol = getIntrinsicTagSymbol(node); + if (links.jsxFlags & JsxFlags.IntrinsicNamedElement) { + return links.resolvedJsxElementAttributesType = getTypeOfSymbol(symbol) || errorType; + } + else if (links.jsxFlags & JsxFlags.IntrinsicIndexedElement) { + const propName = isJsxNamespacedName(node.tagName) ? getEscapedTextOfJsxNamespacedName(node.tagName) : node.tagName.escapedText; + return links.resolvedJsxElementAttributesType = getApplicableIndexInfoForName(getJsxType(JsxNames.IntrinsicElements, node), propName)?.type || errorType; + } + else { + return links.resolvedJsxElementAttributesType = errorType; + } + } + return links.resolvedJsxElementAttributesType; + } + + function getJsxElementClassTypeAt(location: Node): Type | undefined { + const type = getJsxType(JsxNames.ElementClass, location); + if (isErrorType(type)) return undefined; + return type; + } + + function getJsxElementTypeAt(location: Node): Type { + return getJsxType(JsxNames.Element, location); + } + + function getJsxStatelessElementTypeAt(location: Node): Type | undefined { + const jsxElementType = getJsxElementTypeAt(location); + if (jsxElementType) { + return getUnionType([jsxElementType, nullType]); + } + } + + function getJsxElementTypeTypeAt(location: Node): Type | undefined { + const ns = getJsxNamespaceAt(location); + if (!ns) return undefined; + const sym = getJsxElementTypeSymbol(ns); + if (!sym) return undefined; + const type = instantiateAliasOrInterfaceWithDefaults(sym, isInJSFile(location)); + if (!type || isErrorType(type)) return undefined; + return type; + } + + function instantiateAliasOrInterfaceWithDefaults(managedSym: Symbol, inJs: boolean, ...typeArguments: Type[]) { + const declaredManagedType = getDeclaredTypeOfSymbol(managedSym); // fetches interface type, or initializes symbol links type parmaeters + if (managedSym.flags & SymbolFlags.TypeAlias) { + const params = getSymbolLinks(managedSym).typeParameters; + if (length(params) >= typeArguments.length) { + const args = fillMissingTypeArguments(typeArguments, params, typeArguments.length, inJs); + return length(args) === 0 ? declaredManagedType : getTypeAliasInstantiation(managedSym, args); + } + } + if (length((declaredManagedType as GenericType).typeParameters) >= typeArguments.length) { + const args = fillMissingTypeArguments(typeArguments, (declaredManagedType as GenericType).typeParameters, typeArguments.length, inJs); + return createTypeReference(declaredManagedType as GenericType, args); + } + return undefined; + } + + /** + * Returns all the properties of the Jsx.IntrinsicElements interface + */ + function getJsxIntrinsicTagNamesAt(location: Node): Symbol[] { + const intrinsics = getJsxType(JsxNames.IntrinsicElements, location); + return intrinsics ? getPropertiesOfType(intrinsics) : emptyArray; + } + + function checkJsxPreconditions(errorNode: Node) { + // Preconditions for using JSX + if ((compilerOptions.jsx || JsxEmit.None) === JsxEmit.None) { + error(errorNode, Diagnostics.Cannot_use_JSX_unless_the_jsx_flag_is_provided); + } + + if (getJsxElementTypeAt(errorNode) === undefined) { + if (noImplicitAny) { + error(errorNode, Diagnostics.JSX_element_implicitly_has_type_any_because_the_global_type_JSX_Element_does_not_exist); + } + } + } + + function checkJsxOpeningLikeElementOrOpeningFragment(node: JsxOpeningLikeElement | JsxOpeningFragment) { + const isNodeOpeningLikeElement = isJsxOpeningLikeElement(node); + + if (isNodeOpeningLikeElement) { + checkGrammarJsxElement(node); + } + + checkJsxPreconditions(node); + + markLinkedReferences(node, ReferenceHint.Jsx); + + if (isNodeOpeningLikeElement) { + const jsxOpeningLikeNode = node; + const sig = getResolvedSignature(jsxOpeningLikeNode); + checkDeprecatedSignature(sig, node); + + const elementTypeConstraint = getJsxElementTypeTypeAt(jsxOpeningLikeNode); + if (elementTypeConstraint !== undefined) { + const tagName = jsxOpeningLikeNode.tagName; + const tagType = isJsxIntrinsicTagName(tagName) + ? getStringLiteralType(intrinsicTagNameToString(tagName)) + : checkExpression(tagName); + checkTypeRelatedTo(tagType, elementTypeConstraint, assignableRelation, tagName, Diagnostics.Its_type_0_is_not_a_valid_JSX_element_type, () => { + const componentName = getTextOfNode(tagName); + return chainDiagnosticMessages(/*details*/ undefined, Diagnostics._0_cannot_be_used_as_a_JSX_component, componentName); + }); + } + else { + checkJsxReturnAssignableToAppropriateBound(getJsxReferenceKind(jsxOpeningLikeNode), getReturnTypeOfSignature(sig), jsxOpeningLikeNode); + } + } + } + + /** + * Check if a property with the given name is known anywhere in the given type. In an object type, a property + * is considered known if + * 1. the object type is empty and the check is for assignability, or + * 2. if the object type has index signatures, or + * 3. if the property is actually declared in the object type + * (this means that 'toString', for example, is not usually a known property). + * 4. In a union or intersection type, + * a property is considered known if it is known in any constituent type. + * @param targetType a type to search a given name in + * @param name a property name to search + * @param isComparingJsxAttributes a boolean flag indicating whether we are searching in JsxAttributesType + */ + function isKnownProperty(targetType: Type, name: __String, isComparingJsxAttributes: boolean): boolean { + if (targetType.flags & TypeFlags.Object) { + // For backwards compatibility a symbol-named property is satisfied by a string index signature. This + // is incorrect and inconsistent with element access expressions, where it is an error, so eventually + // we should remove this exception. + if ( + getPropertyOfObjectType(targetType, name) || + getApplicableIndexInfoForName(targetType, name) || + isLateBoundName(name) && getIndexInfoOfType(targetType, stringType) || + isComparingJsxAttributes && isHyphenatedJsxName(name) + ) { + // For JSXAttributes, if the attribute has a hyphenated name, consider that the attribute to be known. + return true; + } + } + if (targetType.flags & TypeFlags.Substitution) { + return isKnownProperty((targetType as SubstitutionType).baseType, name, isComparingJsxAttributes); + } + if (targetType.flags & TypeFlags.UnionOrIntersection && isExcessPropertyCheckTarget(targetType)) { + for (const t of (targetType as UnionOrIntersectionType).types) { + if (isKnownProperty(t, name, isComparingJsxAttributes)) { + return true; + } + } + } + return false; + } + + function isExcessPropertyCheckTarget(type: Type): boolean { + return !!(type.flags & TypeFlags.Object && !(getObjectFlags(type) & ObjectFlags.ObjectLiteralPatternWithComputedProperties) || + type.flags & TypeFlags.NonPrimitive || + type.flags & TypeFlags.Substitution && isExcessPropertyCheckTarget((type as SubstitutionType).baseType) || + type.flags & TypeFlags.Union && some((type as UnionType).types, isExcessPropertyCheckTarget) || + type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, isExcessPropertyCheckTarget)); + } + + function checkJsxExpression(node: JsxExpression, checkMode?: CheckMode) { + checkGrammarJsxExpression(node); + if (node.expression) { + const type = checkExpression(node.expression, checkMode); + if (node.dotDotDotToken && type !== anyType && !isArrayType(type)) { + error(node, Diagnostics.JSX_spread_child_must_be_an_array_type); + } + return type; + } + else { + return errorType; + } + } + + function getDeclarationNodeFlagsFromSymbol(s: Symbol): NodeFlags { + return s.valueDeclaration ? getCombinedNodeFlagsCached(s.valueDeclaration) : 0; + } + + /** + * Return whether this symbol is a member of a prototype somewhere + * Note that this is not tracked well within the compiler, so the answer may be incorrect. + */ + function isPrototypeProperty(symbol: Symbol) { + if (symbol.flags & SymbolFlags.Method || getCheckFlags(symbol) & CheckFlags.SyntheticMethod) { + return true; + } + if (isInJSFile(symbol.valueDeclaration)) { + const parent = symbol.valueDeclaration!.parent; + return parent && isBinaryExpression(parent) && + getAssignmentDeclarationKind(parent) === AssignmentDeclarationKind.PrototypeProperty; + } + } + + /** + * Check whether the requested property access is valid. + * Returns true if node is a valid property access, and false otherwise. + * @param node The node to be checked. + * @param isSuper True if the access is from `super.`. + * @param type The type of the object whose property is being accessed. (Not the type of the property.) + * @param prop The symbol for the property being accessed. + */ + function checkPropertyAccessibility( + node: PropertyAccessExpression | QualifiedName | PropertyAccessExpression | VariableDeclaration | ParameterDeclaration | ImportTypeNode | PropertyAssignment | ShorthandPropertyAssignment | BindingElement, + isSuper: boolean, + writing: boolean, + type: Type, + prop: Symbol, + reportError = true, + ): boolean { + const errorNode = !reportError ? undefined : + node.kind === SyntaxKind.QualifiedName ? node.right : + node.kind === SyntaxKind.ImportType ? node : + node.kind === SyntaxKind.BindingElement && node.propertyName ? node.propertyName : node.name; + + return checkPropertyAccessibilityAtLocation(node, isSuper, writing, type, prop, errorNode); + } + + /** + * Check whether the requested property can be accessed at the requested location. + * Returns true if node is a valid property access, and false otherwise. + * @param location The location node where we want to check if the property is accessible. + * @param isSuper True if the access is from `super.`. + * @param writing True if this is a write property access, false if it is a read property access. + * @param containingType The type of the object whose property is being accessed. (Not the type of the property.) + * @param prop The symbol for the property being accessed. + * @param errorNode The node where we should report an invalid property access error, or undefined if we should not report errors. + */ + function checkPropertyAccessibilityAtLocation(location: Node, isSuper: boolean, writing: boolean, containingType: Type, prop: Symbol, errorNode?: Node): boolean { + const flags = getDeclarationModifierFlagsFromSymbol(prop, writing); + + if (isSuper) { + // TS 1.0 spec (April 2014): 4.8.2 + // - In a constructor, instance member function, instance member accessor, or + // instance member variable initializer where this references a derived class instance, + // a super property access is permitted and must specify a public instance member function of the base class. + // - In a static member function or static member accessor + // where this references the constructor function object of a derived class, + // a super property access is permitted and must specify a public static member function of the base class. + if (languageVersion < ScriptTarget.ES2015) { + if (symbolHasNonMethodDeclaration(prop)) { + if (errorNode) { + error(errorNode, Diagnostics.Only_public_and_protected_methods_of_the_base_class_are_accessible_via_the_super_keyword); + } + return false; + } + } + if (flags & ModifierFlags.Abstract) { + // A method cannot be accessed in a super property access if the method is abstract. + // This error could mask a private property access error. But, a member + // cannot simultaneously be private and abstract, so this will trigger an + // additional error elsewhere. + if (errorNode) { + error(errorNode, Diagnostics.Abstract_method_0_in_class_1_cannot_be_accessed_via_super_expression, symbolToString(prop), typeToString(getDeclaringClass(prop)!)); + } + return false; + } + // A class field cannot be accessed via super.* from a derived class. + // This is true for both [[Set]] (old) and [[Define]] (ES spec) semantics. + if (!(flags & ModifierFlags.Static) && prop.declarations?.some(isClassInstanceProperty)) { + if (errorNode) { + error(errorNode, Diagnostics.Class_field_0_defined_by_the_parent_class_is_not_accessible_in_the_child_class_via_super, symbolToString(prop)); + } + return false; + } + } + + // Referencing abstract properties within their own constructors is not allowed + if ( + (flags & ModifierFlags.Abstract) && symbolHasNonMethodDeclaration(prop) && + (isThisProperty(location) || isThisInitializedObjectBindingExpression(location) || isObjectBindingPattern(location.parent) && isThisInitializedDeclaration(location.parent.parent)) + ) { + const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(getParentOfSymbol(prop)!); + if (declaringClassDeclaration && isNodeUsedDuringClassInitialization(location)) { + if (errorNode) { + error(errorNode, Diagnostics.Abstract_property_0_in_class_1_cannot_be_accessed_in_the_constructor, symbolToString(prop), getTextOfIdentifierOrLiteral(declaringClassDeclaration.name!)); + } + return false; + } + } + + // Public properties are otherwise accessible. + if (!(flags & ModifierFlags.NonPublicAccessibilityModifier)) { + return true; + } + + // Property is known to be private or protected at this point + + // Private property is accessible if the property is within the declaring class + if (flags & ModifierFlags.Private) { + const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(getParentOfSymbol(prop)!)!; + if (!isNodeWithinClass(location, declaringClassDeclaration)) { + if (errorNode) { + error(errorNode, Diagnostics.Property_0_is_private_and_only_accessible_within_class_1, symbolToString(prop), typeToString(getDeclaringClass(prop)!)); + } + return false; + } + return true; + } + + // Property is known to be protected at this point + + // All protected properties of a supertype are accessible in a super access + if (isSuper) { + return true; + } + + // Find the first enclosing class that has the declaring classes of the protected constituents + // of the property as base classes + let enclosingClass = forEachEnclosingClass(location, enclosingDeclaration => { + const enclosingClass = getDeclaredTypeOfSymbol(getSymbolOfDeclaration(enclosingDeclaration)) as InterfaceType; + return isClassDerivedFromDeclaringClasses(enclosingClass, prop, writing); + }); + // A protected property is accessible if the property is within the declaring class or classes derived from it + if (!enclosingClass) { + // allow PropertyAccessibility if context is in function with this parameter + // static member access is disallowed + enclosingClass = getEnclosingClassFromThisParameter(location); + enclosingClass = enclosingClass && isClassDerivedFromDeclaringClasses(enclosingClass, prop, writing); + if (flags & ModifierFlags.Static || !enclosingClass) { + if (errorNode) { + error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_within_class_1_and_its_subclasses, symbolToString(prop), typeToString(getDeclaringClass(prop) || containingType)); + } + return false; + } + } + // No further restrictions for static properties + if (flags & ModifierFlags.Static) { + return true; + } + if (containingType.flags & TypeFlags.TypeParameter) { + // get the original type -- represented as the type constraint of the 'this' type + containingType = (containingType as TypeParameter).isThisType ? getConstraintOfTypeParameter(containingType as TypeParameter)! : getBaseConstraintOfType(containingType as TypeParameter)!; // TODO: GH#18217 Use a different variable that's allowed to be undefined + } + if (!containingType || !hasBaseType(containingType, enclosingClass)) { + if (errorNode) { + error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_through_an_instance_of_class_1_This_is_an_instance_of_class_2, symbolToString(prop), typeToString(enclosingClass), typeToString(containingType)); + } + return false; + } + return true; + } + + function getEnclosingClassFromThisParameter(node: Node): InterfaceType | undefined { + const thisParameter = getThisParameterFromNodeContext(node); + let thisType = thisParameter?.type && getTypeFromTypeNode(thisParameter.type); + if (thisType && thisType.flags & TypeFlags.TypeParameter) { + thisType = getConstraintOfTypeParameter(thisType as TypeParameter); + } + if (thisType && getObjectFlags(thisType) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference)) { + return getTargetType(thisType) as InterfaceType; + } + return undefined; + } + + function getThisParameterFromNodeContext(node: Node) { + const thisContainer = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + return thisContainer && isFunctionLike(thisContainer) ? getThisParameter(thisContainer) : undefined; + } + + function symbolHasNonMethodDeclaration(symbol: Symbol) { + return !!forEachProperty(symbol, prop => !(prop.flags & SymbolFlags.Method)); + } + + function checkNonNullExpression(node: Expression | QualifiedName) { + return checkNonNullType(checkExpression(node), node); + } + + function isNullableType(type: Type) { + return hasTypeFacts(type, TypeFacts.IsUndefinedOrNull); + } + + function getNonNullableTypeIfNeeded(type: Type) { + return isNullableType(type) ? getNonNullableType(type) : type; + } + + function reportObjectPossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) { + const nodeText = isEntityNameExpression(node) ? entityNameToString(node) : undefined; + if (node.kind === SyntaxKind.NullKeyword) { + error(node, Diagnostics.The_value_0_cannot_be_used_here, "null"); + return; + } + if (nodeText !== undefined && nodeText.length < 100) { + if (isIdentifier(node) && nodeText === "undefined") { + error(node, Diagnostics.The_value_0_cannot_be_used_here, "undefined"); + return; + } + error( + node, + facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? + Diagnostics._0_is_possibly_null_or_undefined : + Diagnostics._0_is_possibly_undefined : + Diagnostics._0_is_possibly_null, + nodeText, + ); + } + else { + error( + node, + facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? + Diagnostics.Object_is_possibly_null_or_undefined : + Diagnostics.Object_is_possibly_undefined : + Diagnostics.Object_is_possibly_null, + ); + } + } + + function reportCannotInvokePossiblyNullOrUndefinedError(node: Node, facts: TypeFacts) { + error( + node, + facts & TypeFacts.IsUndefined ? facts & TypeFacts.IsNull ? + Diagnostics.Cannot_invoke_an_object_which_is_possibly_null_or_undefined : + Diagnostics.Cannot_invoke_an_object_which_is_possibly_undefined : + Diagnostics.Cannot_invoke_an_object_which_is_possibly_null, + ); + } + + function checkNonNullTypeWithReporter( + type: Type, + node: Node, + reportError: (node: Node, facts: TypeFacts) => void, + ): Type { + if (strictNullChecks && type.flags & TypeFlags.Unknown) { + if (isEntityNameExpression(node)) { + const nodeText = entityNameToString(node); + if (nodeText.length < 100) { + error(node, Diagnostics._0_is_of_type_unknown, nodeText); + return errorType; + } + } + error(node, Diagnostics.Object_is_of_type_unknown); + return errorType; + } + const facts = getTypeFacts(type, TypeFacts.IsUndefinedOrNull); + if (facts & TypeFacts.IsUndefinedOrNull) { + reportError(node, facts); + const t = getNonNullableType(type); + return t.flags & (TypeFlags.Nullable | TypeFlags.Never) ? errorType : t; + } + return type; + } + + function checkNonNullType(type: Type, node: Node) { + return checkNonNullTypeWithReporter(type, node, reportObjectPossiblyNullOrUndefinedError); + } + + function checkNonNullNonVoidType(type: Type, node: Node): Type { + const nonNullType = checkNonNullType(type, node); + if (nonNullType.flags & TypeFlags.Void) { + if (isEntityNameExpression(node)) { + const nodeText = entityNameToString(node); + if (isIdentifier(node) && nodeText === "undefined") { + error(node, Diagnostics.The_value_0_cannot_be_used_here, nodeText); + return nonNullType; + } + if (nodeText.length < 100) { + error(node, Diagnostics._0_is_possibly_undefined, nodeText); + return nonNullType; + } + } + error(node, Diagnostics.Object_is_possibly_undefined); + } + return nonNullType; + } + + function checkPropertyAccessExpression(node: PropertyAccessExpression, checkMode: CheckMode | undefined, writeOnly?: boolean) { + return node.flags & NodeFlags.OptionalChain ? checkPropertyAccessChain(node as PropertyAccessChain, checkMode) : + checkPropertyAccessExpressionOrQualifiedName(node, node.expression, checkNonNullExpression(node.expression), node.name, checkMode, writeOnly); + } + + function checkPropertyAccessChain(node: PropertyAccessChain, checkMode: CheckMode | undefined) { + const leftType = checkExpression(node.expression); + const nonOptionalType = getOptionalExpressionType(leftType, node.expression); + return propagateOptionalTypeMarker(checkPropertyAccessExpressionOrQualifiedName(node, node.expression, checkNonNullType(nonOptionalType, node.expression), node.name, checkMode), node, nonOptionalType !== leftType); + } + + function checkQualifiedName(node: QualifiedName, checkMode: CheckMode | undefined) { + const leftType = isPartOfTypeQuery(node) && isThisIdentifier(node.left) ? checkNonNullType(checkThisExpression(node.left), node.left) : checkNonNullExpression(node.left); + return checkPropertyAccessExpressionOrQualifiedName(node, node.left, leftType, node.right, checkMode); + } + + function isMethodAccessForCall(node: Node) { + while (node.parent.kind === SyntaxKind.ParenthesizedExpression) { + node = node.parent; + } + return isCallOrNewExpression(node.parent) && node.parent.expression === node; + } + + // Lookup the private identifier lexically. + function lookupSymbolForPrivateIdentifierDeclaration(propName: __String, location: Node): Symbol | undefined { + for (let containingClass = getContainingClassExcludingClassDecorators(location); !!containingClass; containingClass = getContainingClass(containingClass)) { + const { symbol } = containingClass; + const name = getSymbolNameForPrivateIdentifier(symbol, propName); + const prop = (symbol.members && symbol.members.get(name)) || (symbol.exports && symbol.exports.get(name)); + if (prop) { + return prop; + } + } + } + + function checkGrammarPrivateIdentifierExpression(privId: PrivateIdentifier): boolean { + if (!getContainingClass(privId)) { + return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + + if (!isForInStatement(privId.parent)) { + if (!isExpressionNode(privId)) { + return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_only_allowed_in_class_bodies_and_may_only_be_used_as_part_of_a_class_member_declaration_property_access_or_on_the_left_hand_side_of_an_in_expression); + } + + const isInOperation = isBinaryExpression(privId.parent) && privId.parent.operatorToken.kind === SyntaxKind.InKeyword; + if (!getSymbolForPrivateIdentifierExpression(privId) && !isInOperation) { + return grammarErrorOnNode(privId, Diagnostics.Cannot_find_name_0, idText(privId)); + } + } + + return false; + } + + function checkPrivateIdentifierExpression(privId: PrivateIdentifier): Type { + checkGrammarPrivateIdentifierExpression(privId); + const symbol = getSymbolForPrivateIdentifierExpression(privId); + if (symbol) { + markPropertyAsReferenced(symbol, /*nodeForCheckWriteOnly*/ undefined, /*isSelfTypeAccess*/ false); + } + return anyType; + } + + function getSymbolForPrivateIdentifierExpression(privId: PrivateIdentifier): Symbol | undefined { + if (!isExpressionNode(privId)) { + return undefined; + } + + const links = getNodeLinks(privId); + if (links.resolvedSymbol === undefined) { + links.resolvedSymbol = lookupSymbolForPrivateIdentifierDeclaration(privId.escapedText, privId); + } + return links.resolvedSymbol; + } + + function getPrivateIdentifierPropertyOfType(leftType: Type, lexicallyScopedIdentifier: Symbol): Symbol | undefined { + return getPropertyOfType(leftType, lexicallyScopedIdentifier.escapedName); + } + + function checkPrivateIdentifierPropertyAccess(leftType: Type, right: PrivateIdentifier, lexicallyScopedIdentifier: Symbol | undefined): boolean { + // Either the identifier could not be looked up in the lexical scope OR the lexically scoped identifier did not exist on the type. + // Find a private identifier with the same description on the type. + let propertyOnType: Symbol | undefined; + const properties = getPropertiesOfType(leftType); + if (properties) { + forEach(properties, (symbol: Symbol) => { + const decl = symbol.valueDeclaration; + if (decl && isNamedDeclaration(decl) && isPrivateIdentifier(decl.name) && decl.name.escapedText === right.escapedText) { + propertyOnType = symbol; + return true; + } + }); + } + const diagName = diagnosticName(right); + if (propertyOnType) { + const typeValueDecl = Debug.checkDefined(propertyOnType.valueDeclaration); + const typeClass = Debug.checkDefined(getContainingClass(typeValueDecl)); + // We found a private identifier property with the same description. + // Either: + // - There is a lexically scoped private identifier AND it shadows the one we found on the type. + // - It is an attempt to access the private identifier outside of the class. + if (lexicallyScopedIdentifier?.valueDeclaration) { + const lexicalValueDecl = lexicallyScopedIdentifier.valueDeclaration; + const lexicalClass = getContainingClass(lexicalValueDecl); + Debug.assert(!!lexicalClass); + if (findAncestor(lexicalClass, n => typeClass === n)) { + const diagnostic = error( + right, + Diagnostics.The_property_0_cannot_be_accessed_on_type_1_within_this_class_because_it_is_shadowed_by_another_private_identifier_with_the_same_spelling, + diagName, + typeToString(leftType), + ); + + addRelatedInfo( + diagnostic, + createDiagnosticForNode( + lexicalValueDecl, + Diagnostics.The_shadowing_declaration_of_0_is_defined_here, + diagName, + ), + createDiagnosticForNode( + typeValueDecl, + Diagnostics.The_declaration_of_0_that_you_probably_intended_to_use_is_defined_here, + diagName, + ), + ); + return true; + } + } + error( + right, + Diagnostics.Property_0_is_not_accessible_outside_class_1_because_it_has_a_private_identifier, + diagName, + diagnosticName(typeClass.name || anon), + ); + return true; + } + return false; + } + + function isThisPropertyAccessInConstructor(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol) { + return (isConstructorDeclaredProperty(prop) || isThisProperty(node) && isAutoTypedProperty(prop)) + && getThisContainer(node, /*includeArrowFunctions*/ true, /*includeClassComputedPropertyName*/ false) === getDeclaringConstructor(prop); + } + + function checkPropertyAccessExpressionOrQualifiedName(node: PropertyAccessExpression | QualifiedName, left: Expression | QualifiedName, leftType: Type, right: Identifier | PrivateIdentifier, checkMode: CheckMode | undefined, writeOnly?: boolean) { + const parentSymbol = getNodeLinks(left).resolvedSymbol; + const assignmentKind = getAssignmentTargetKind(node); + const apparentType = getApparentType(assignmentKind !== AssignmentKind.None || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType); + const isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType; + let prop: Symbol | undefined; + if (isPrivateIdentifier(right)) { + if ( + languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators || + !useDefineForClassFields + ) { + if (assignmentKind !== AssignmentKind.None) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ClassPrivateFieldSet); + } + if (assignmentKind !== AssignmentKind.Definite) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.ClassPrivateFieldGet); + } + } + + const lexicallyScopedSymbol = lookupSymbolForPrivateIdentifierDeclaration(right.escapedText, right); + if (assignmentKind && lexicallyScopedSymbol && lexicallyScopedSymbol.valueDeclaration && isMethodDeclaration(lexicallyScopedSymbol.valueDeclaration)) { + grammarErrorOnNode(right, Diagnostics.Cannot_assign_to_private_method_0_Private_methods_are_not_writable, idText(right)); + } + if (isAnyLike) { + if (lexicallyScopedSymbol) { + return isErrorType(apparentType) ? errorType : apparentType; + } + if (getContainingClassExcludingClassDecorators(right) === undefined) { + grammarErrorOnNode(right, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + return anyType; + } + } + + prop = lexicallyScopedSymbol && getPrivateIdentifierPropertyOfType(leftType, lexicallyScopedSymbol); + if (prop === undefined) { + // Check for private-identifier-specific shadowing and lexical-scoping errors. + if (checkPrivateIdentifierPropertyAccess(leftType, right, lexicallyScopedSymbol)) { + return errorType; + } + const containingClass = getContainingClassExcludingClassDecorators(right); + if (containingClass && isPlainJsFile(getSourceFileOfNode(containingClass), compilerOptions.checkJs)) { + grammarErrorOnNode(right, Diagnostics.Private_field_0_must_be_declared_in_an_enclosing_class, idText(right)); + } + } + else { + const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); + if (isSetonlyAccessor && assignmentKind !== AssignmentKind.Definite) { + error(node, Diagnostics.Private_accessor_was_defined_without_a_getter); + } + } + } + else { + if (isAnyLike) { + if (isIdentifier(left) && parentSymbol) { + markLinkedReferences(node, ReferenceHint.Property, /*propSymbol*/ undefined, leftType); + } + return isErrorType(apparentType) ? errorType : apparentType; + } + prop = getPropertyOfType(apparentType, right.escapedText, /*skipObjectFunctionPropertyAugment*/ isConstEnumObjectType(apparentType), /*includeTypeOnlyMembers*/ node.kind === SyntaxKind.QualifiedName); + } + markLinkedReferences(node, ReferenceHint.Property, prop, leftType); + + let propType: Type; + if (!prop) { + const indexInfo = !isPrivateIdentifier(right) && (assignmentKind === AssignmentKind.None || !isGenericObjectType(leftType) || isThisTypeParameter(leftType)) ? + getApplicableIndexInfoForName(apparentType, right.escapedText) : undefined; + if (!(indexInfo && indexInfo.type)) { + const isUncheckedJS = isUncheckedJSSuggestion(node, leftType.symbol, /*excludeClasses*/ true); + if (!isUncheckedJS && isJSLiteralType(leftType)) { + return anyType; + } + if (leftType.symbol === globalThisSymbol) { + if (globalThisSymbol.exports!.has(right.escapedText) && (globalThisSymbol.exports!.get(right.escapedText)!.flags & SymbolFlags.BlockScoped)) { + error(right, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(right.escapedText), typeToString(leftType)); + } + else if (noImplicitAny) { + error(right, Diagnostics.Element_implicitly_has_an_any_type_because_type_0_has_no_index_signature, typeToString(leftType)); + } + return anyType; + } + if (right.escapedText && !checkAndReportErrorForExtendingInterface(node)) { + reportNonexistentProperty(right, isThisTypeParameter(leftType) ? apparentType : leftType, isUncheckedJS); + } + return errorType; + } + if (indexInfo.isReadonly && (isAssignmentTarget(node) || isDeleteTarget(node))) { + error(node, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(apparentType)); + } + + propType = indexInfo.type; + if (compilerOptions.noUncheckedIndexedAccess && getAssignmentTargetKind(node) !== AssignmentKind.Definite) { + propType = getUnionType([propType, missingType]); + } + if (compilerOptions.noPropertyAccessFromIndexSignature && isPropertyAccessExpression(node)) { + error(right, Diagnostics.Property_0_comes_from_an_index_signature_so_it_must_be_accessed_with_0, unescapeLeadingUnderscores(right.escapedText)); + } + if (indexInfo.declaration && isDeprecatedDeclaration(indexInfo.declaration)) { + addDeprecatedSuggestion(right, [indexInfo.declaration], right.escapedText as string); + } + } + else { + const targetPropSymbol = resolveAliasWithDeprecationCheck(prop, right); + if (isDeprecatedSymbol(targetPropSymbol) && isUncalledFunctionReference(node, targetPropSymbol) && targetPropSymbol.declarations) { + addDeprecatedSuggestion(right, targetPropSymbol.declarations, right.escapedText as string); + } + checkPropertyNotUsedBeforeDeclaration(prop, node, right); + markPropertyAsReferenced(prop, node, isSelfTypeAccess(left, parentSymbol)); + getNodeLinks(node).resolvedSymbol = prop; + checkPropertyAccessibility(node, left.kind === SyntaxKind.SuperKeyword, isWriteAccess(node), apparentType, prop); + if (isAssignmentToReadonlyEntity(node as Expression, prop, assignmentKind)) { + error(right, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, idText(right)); + return errorType; + } + + propType = isThisPropertyAccessInConstructor(node, prop) ? autoType : writeOnly || isWriteOnlyAccess(node) ? getWriteTypeOfSymbol(prop) : getTypeOfSymbol(prop); + } + + return getFlowTypeOfAccessExpression(node, prop, propType, right, checkMode); + } + + /** + * Determines whether a did-you-mean error should be a suggestion in an unchecked JS file. + * Only applies to unchecked JS files without checkJS, // @ts-check or // @ts-nocheck + * It does not suggest when the suggestion: + * - Is from a global file that is different from the reference file, or + * - (optionally) Is a class, or is a this.x property access expression + */ + function isUncheckedJSSuggestion(node: Node | undefined, suggestion: Symbol | undefined, excludeClasses: boolean): boolean { + const file = getSourceFileOfNode(node); + if (file) { + if (compilerOptions.checkJs === undefined && file.checkJsDirective === undefined && (file.scriptKind === ScriptKind.JS || file.scriptKind === ScriptKind.JSX)) { + const declarationFile = forEach(suggestion?.declarations, getSourceFileOfNode); + const suggestionHasNoExtendsOrDecorators = !suggestion?.valueDeclaration + || !isClassLike(suggestion.valueDeclaration) + || suggestion.valueDeclaration.heritageClauses?.length + || classOrConstructorParameterIsDecorated(/*useLegacyDecorators*/ false, suggestion.valueDeclaration); + return !(file !== declarationFile && !!declarationFile && isGlobalSourceFile(declarationFile)) + && !(excludeClasses && suggestion && suggestion.flags & SymbolFlags.Class && suggestionHasNoExtendsOrDecorators) + && !(!!node && excludeClasses && isPropertyAccessExpression(node) && node.expression.kind === SyntaxKind.ThisKeyword && suggestionHasNoExtendsOrDecorators); + } + } + return false; + } + + function getFlowTypeOfAccessExpression(node: ElementAccessExpression | PropertyAccessExpression | QualifiedName, prop: Symbol | undefined, propType: Type, errorNode: Node, checkMode: CheckMode | undefined) { + // Only compute control flow type if this is a property access expression that isn't an + // assignment target, and the referenced property was declared as a variable, property, + // accessor, or optional method. + const assignmentKind = getAssignmentTargetKind(node); + if (assignmentKind === AssignmentKind.Definite) { + return removeMissingType(propType, !!(prop && prop.flags & SymbolFlags.Optional)); + } + if ( + prop && + !(prop.flags & (SymbolFlags.Variable | SymbolFlags.Property | SymbolFlags.Accessor)) + && !(prop.flags & SymbolFlags.Method && propType.flags & TypeFlags.Union) + && !isDuplicatedCommonJSExport(prop.declarations) + ) { + return propType; + } + if (propType === autoType) { + return getFlowTypeOfProperty(node, prop); + } + propType = getNarrowableTypeForReference(propType, node, checkMode); + // If strict null checks and strict property initialization checks are enabled, if we have + // a this.xxx property access, if the property is an instance property without an initializer, + // and if we are in a constructor of the same class as the property declaration, assume that + // the property is uninitialized at the top of the control flow. + let assumeUninitialized = false; + if (strictNullChecks && strictPropertyInitialization && isAccessExpression(node) && node.expression.kind === SyntaxKind.ThisKeyword) { + const declaration = prop && prop.valueDeclaration; + if (declaration && isPropertyWithoutInitializer(declaration)) { + if (!isStatic(declaration)) { + const flowContainer = getControlFlowContainer(node); + if (flowContainer.kind === SyntaxKind.Constructor && flowContainer.parent === declaration.parent && !(declaration.flags & NodeFlags.Ambient)) { + assumeUninitialized = true; + } + } + } + } + else if ( + strictNullChecks && prop && prop.valueDeclaration && + isPropertyAccessExpression(prop.valueDeclaration) && + getAssignmentDeclarationPropertyAccessKind(prop.valueDeclaration) && + getControlFlowContainer(node) === getControlFlowContainer(prop.valueDeclaration) + ) { + assumeUninitialized = true; + } + const flowType = getFlowTypeOfReference(node, propType, assumeUninitialized ? getOptionalType(propType) : propType); + if (assumeUninitialized && !containsUndefinedType(propType) && containsUndefinedType(flowType)) { + error(errorNode, Diagnostics.Property_0_is_used_before_being_assigned, symbolToString(prop!)); // TODO: GH#18217 + // Return the declared type to reduce follow-on errors + return propType; + } + return assignmentKind ? getBaseTypeOfLiteralType(flowType) : flowType; + } + + function checkPropertyNotUsedBeforeDeclaration(prop: Symbol, node: PropertyAccessExpression | QualifiedName, right: Identifier | PrivateIdentifier): void { + const { valueDeclaration } = prop; + if (!valueDeclaration || getSourceFileOfNode(node).isDeclarationFile) { + return; + } + + let diagnosticMessage; + const declarationName = idText(right); + if ( + isInPropertyInitializerOrClassStaticBlock(node) + && !isOptionalPropertyDeclaration(valueDeclaration) + && !(isAccessExpression(node) && isAccessExpression(node.expression)) + && !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right) + && !(isMethodDeclaration(valueDeclaration) && getCombinedModifierFlagsCached(valueDeclaration) & ModifierFlags.Static) + && (useDefineForClassFields || !isPropertyDeclaredInAncestorClass(prop)) + ) { + diagnosticMessage = error(right, Diagnostics.Property_0_is_used_before_its_initialization, declarationName); + } + else if ( + valueDeclaration.kind === SyntaxKind.ClassDeclaration && + node.parent.kind !== SyntaxKind.TypeReference && + !(valueDeclaration.flags & NodeFlags.Ambient) && + !isBlockScopedNameDeclaredBeforeUse(valueDeclaration, right) + ) { + diagnosticMessage = error(right, Diagnostics.Class_0_used_before_its_declaration, declarationName); + } + + if (diagnosticMessage) { + addRelatedInfo(diagnosticMessage, createDiagnosticForNode(valueDeclaration, Diagnostics._0_is_declared_here, declarationName)); + } + } + + function isInPropertyInitializerOrClassStaticBlock(node: Node): boolean { + return !!findAncestor(node, node => { + switch (node.kind) { + case SyntaxKind.PropertyDeclaration: + return true; + case SyntaxKind.PropertyAssignment: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.SpreadAssignment: + case SyntaxKind.ComputedPropertyName: + case SyntaxKind.TemplateSpan: + case SyntaxKind.JsxExpression: + case SyntaxKind.JsxAttribute: + case SyntaxKind.JsxAttributes: + case SyntaxKind.JsxSpreadAttribute: + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.ExpressionWithTypeArguments: + case SyntaxKind.HeritageClause: + return false; + case SyntaxKind.ArrowFunction: + case SyntaxKind.ExpressionStatement: + return isBlock(node.parent) && isClassStaticBlockDeclaration(node.parent.parent) ? true : "quit"; + default: + return isExpressionNode(node) ? false : "quit"; + } + }); + } + + /** + * It's possible that "prop.valueDeclaration" is a local declaration, but the property was also declared in a superclass. + * In that case we won't consider it used before its declaration, because it gets its value from the superclass' declaration. + */ + function isPropertyDeclaredInAncestorClass(prop: Symbol): boolean { + if (!(prop.parent!.flags & SymbolFlags.Class)) { + return false; + } + let classType: InterfaceType | undefined = getTypeOfSymbol(prop.parent!) as InterfaceType; + while (true) { + classType = classType.symbol && getSuperClass(classType) as InterfaceType | undefined; + if (!classType) { + return false; + } + const superProperty = getPropertyOfType(classType, prop.escapedName); + if (superProperty && superProperty.valueDeclaration) { + return true; + } + } + } + + function getSuperClass(classType: InterfaceType): Type | undefined { + const x = getBaseTypes(classType); + if (x.length === 0) { + return undefined; + } + return getIntersectionType(x); + } + + function reportNonexistentProperty(propNode: Identifier | PrivateIdentifier, containingType: Type, isUncheckedJS: boolean) { + let errorInfo: DiagnosticMessageChain | undefined; + let relatedInfo: Diagnostic | undefined; + if (!isPrivateIdentifier(propNode) && containingType.flags & TypeFlags.Union && !(containingType.flags & TypeFlags.Primitive)) { + for (const subtype of (containingType as UnionType).types) { + if (!getPropertyOfType(subtype, propNode.escapedText) && !getApplicableIndexInfoForName(subtype, propNode.escapedText)) { + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1, declarationNameToString(propNode), typeToString(subtype)); + break; + } + } + } + if (typeHasStaticProperty(propNode.escapedText, containingType)) { + const propName = declarationNameToString(propNode); + const typeName = typeToString(containingType); + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_to_access_the_static_member_2_instead, propName, typeName, typeName + "." + propName); + } + else { + const promisedType = getPromisedTypeOfPromise(containingType); + if (promisedType && getPropertyOfType(promisedType, propNode.escapedText)) { + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1, declarationNameToString(propNode), typeToString(containingType)); + relatedInfo = createDiagnosticForNode(propNode, Diagnostics.Did_you_forget_to_use_await); + } + else { + const missingProperty = declarationNameToString(propNode); + const container = typeToString(containingType); + const libSuggestion = getSuggestedLibForNonExistentProperty(missingProperty, containingType); + if (libSuggestion !== undefined) { + errorInfo = chainDiagnosticMessages(errorInfo, Diagnostics.Property_0_does_not_exist_on_type_1_Do_you_need_to_change_your_target_library_Try_changing_the_lib_compiler_option_to_2_or_later, missingProperty, container, libSuggestion); + } + else { + const suggestion = getSuggestedSymbolForNonexistentProperty(propNode, containingType); + if (suggestion !== undefined) { + const suggestedName = symbolName(suggestion); + const message = isUncheckedJS ? Diagnostics.Property_0_may_not_exist_on_type_1_Did_you_mean_2 : Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2; + errorInfo = chainDiagnosticMessages(errorInfo, message, missingProperty, container, suggestedName); + relatedInfo = suggestion.valueDeclaration && createDiagnosticForNode(suggestion.valueDeclaration, Diagnostics._0_is_declared_here, suggestedName); + } + else { + const diagnostic = containerSeemsToBeEmptyDomElement(containingType) + ? Diagnostics.Property_0_does_not_exist_on_type_1_Try_changing_the_lib_compiler_option_to_include_dom + : Diagnostics.Property_0_does_not_exist_on_type_1; + errorInfo = chainDiagnosticMessages(elaborateNeverIntersection(errorInfo, containingType), diagnostic, missingProperty, container); + } + } + } + } + const resultDiagnostic = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(propNode), propNode, errorInfo); + if (relatedInfo) { + addRelatedInfo(resultDiagnostic, relatedInfo); + } + addErrorOrSuggestion(!isUncheckedJS || errorInfo.code !== Diagnostics.Property_0_may_not_exist_on_type_1_Did_you_mean_2.code, resultDiagnostic); + } + + function containerSeemsToBeEmptyDomElement(containingType: Type) { + return (compilerOptions.lib && !compilerOptions.lib.includes("dom")) && + everyContainedType(containingType, type => type.symbol && /^(EventTarget|Node|((HTML[a-zA-Z]*)?Element))$/.test(unescapeLeadingUnderscores(type.symbol.escapedName))) && + isEmptyObjectType(containingType); + } + + function typeHasStaticProperty(propName: __String, containingType: Type): boolean { + const prop = containingType.symbol && getPropertyOfType(getTypeOfSymbol(containingType.symbol), propName); + return prop !== undefined && !!prop.valueDeclaration && isStatic(prop.valueDeclaration); + } + + function getSuggestedLibForNonExistentName(name: __String | Identifier) { + const missingName = diagnosticName(name); + const allFeatures = getScriptTargetFeatures(); + const typeFeatures = allFeatures.get(missingName); + return typeFeatures && firstIterator(typeFeatures.keys()); + } + + function getSuggestedLibForNonExistentProperty(missingProperty: string, containingType: Type) { + const container = getApparentType(containingType).symbol; + if (!container) { + return undefined; + } + const containingTypeName = symbolName(container); + const allFeatures = getScriptTargetFeatures(); + const typeFeatures = allFeatures.get(containingTypeName); + if (typeFeatures) { + for (const [libTarget, featuresOfType] of typeFeatures) { + if (contains(featuresOfType, missingProperty)) { + return libTarget; + } + } + } + } + + function getSuggestedSymbolForNonexistentClassMember(name: string, baseType: Type): Symbol | undefined { + return getSpellingSuggestionForName(name, getPropertiesOfType(baseType), SymbolFlags.ClassMember); + } + + function getSuggestedSymbolForNonexistentProperty(name: Identifier | PrivateIdentifier | string, containingType: Type): Symbol | undefined { + let props = getPropertiesOfType(containingType); + if (typeof name !== "string") { + const parent = name.parent; + if (isPropertyAccessExpression(parent)) { + props = filter(props, prop => isValidPropertyAccessForCompletions(parent, containingType, prop)); + } + name = idText(name); + } + return getSpellingSuggestionForName(name, props, SymbolFlags.Value); + } + + function getSuggestedSymbolForNonexistentJSXAttribute(name: Identifier | PrivateIdentifier | string, containingType: Type): Symbol | undefined { + const strName = isString(name) ? name : idText(name); + const properties = getPropertiesOfType(containingType); + const jsxSpecific = strName === "for" ? find(properties, x => symbolName(x) === "htmlFor") + : strName === "class" ? find(properties, x => symbolName(x) === "className") + : undefined; + return jsxSpecific ?? getSpellingSuggestionForName(strName, properties, SymbolFlags.Value); + } + + function getSuggestionForNonexistentProperty(name: Identifier | PrivateIdentifier | string, containingType: Type): string | undefined { + const suggestion = getSuggestedSymbolForNonexistentProperty(name, containingType); + return suggestion && symbolName(suggestion); + } + + function getSuggestionForSymbolNameLookup(symbols: SymbolTable, name: __String, meaning: SymbolFlags) { + const symbol = getSymbol(symbols, name, meaning); + // Sometimes the symbol is found when location is a return type of a function: `typeof x` and `x` is declared in the body of the function + // So the table *contains* `x` but `x` isn't actually in scope. + // However, resolveNameHelper will continue and call this callback again, so we'll eventually get a correct suggestion. + if (symbol) return symbol; + let candidates: Symbol[]; + if (symbols === globals) { + const primitives = mapDefined( + ["string", "number", "boolean", "object", "bigint", "symbol"], + s => symbols.has((s.charAt(0).toUpperCase() + s.slice(1)) as __String) + ? createSymbol(SymbolFlags.TypeAlias, s as __String) as Symbol + : undefined, + ); + candidates = primitives.concat(arrayFrom(symbols.values())); + } + else { + candidates = arrayFrom(symbols.values()); + } + return getSpellingSuggestionForName(unescapeLeadingUnderscores(name), candidates, meaning); + } + function getSuggestedSymbolForNonexistentSymbol(location: Node | undefined, outerName: __String, meaning: SymbolFlags): Symbol | undefined { + Debug.assert(outerName !== undefined, "outername should always be defined"); + const result = resolveNameForSymbolSuggestion(location, outerName, meaning, /*nameNotFoundMessage*/ undefined, /*isUse*/ false, /*excludeGlobals*/ false); + return result; + } + + function getSuggestedSymbolForNonexistentModule(name: Identifier, targetModule: Symbol): Symbol | undefined { + return targetModule.exports && getSpellingSuggestionForName(idText(name), getExportsOfModuleAsArray(targetModule), SymbolFlags.ModuleMember); + } + + function getSuggestionForNonexistentIndexSignature(objectType: Type, expr: ElementAccessExpression, keyedType: Type): string | undefined { + // check if object type has setter or getter + function hasProp(name: "set" | "get") { + const prop = getPropertyOfObjectType(objectType, name as __String); + if (prop) { + const s = getSingleCallSignature(getTypeOfSymbol(prop)); + return !!s && getMinArgumentCount(s) >= 1 && isTypeAssignableTo(keyedType, getTypeAtPosition(s, 0)); + } + return false; + } + + const suggestedMethod = isAssignmentTarget(expr) ? "set" : "get"; + if (!hasProp(suggestedMethod)) { + return undefined; + } + + let suggestion = tryGetPropertyAccessOrIdentifierToString(expr.expression); + if (suggestion === undefined) { + suggestion = suggestedMethod; + } + else { + suggestion += "." + suggestedMethod; + } + + return suggestion; + } + + function getSuggestedTypeForNonexistentStringLiteralType(source: StringLiteralType, target: UnionType): StringLiteralType | undefined { + const candidates = target.types.filter((type): type is StringLiteralType => !!(type.flags & TypeFlags.StringLiteral)); + return getSpellingSuggestion(source.value, candidates, type => type.value); + } + + /** + * Given a name and a list of symbols whose names are *not* equal to the name, return a spelling suggestion if there is one that is close enough. + * Names less than length 3 only check for case-insensitive equality, not levenshtein distance. + * + * If there is a candidate that's the same except for case, return that. + * If there is a candidate that's within one edit of the name, return that. + * Otherwise, return the candidate with the smallest Levenshtein distance, + * except for candidates: + * * With no name + * * Whose meaning doesn't match the `meaning` parameter. + * * Whose length differs from the target name by more than 0.34 of the length of the name. + * * Whose levenshtein distance is more than 0.4 of the length of the name + * (0.4 allows 1 substitution/transposition for every 5 characters, + * and 1 insertion/deletion at 3 characters) + */ + function getSpellingSuggestionForName(name: string, symbols: Symbol[], meaning: SymbolFlags): Symbol | undefined { + return getSpellingSuggestion(name, symbols, getCandidateName); + + function getCandidateName(candidate: Symbol) { + const candidateName = symbolName(candidate); + if (startsWith(candidateName, '"')) { + return undefined; + } + + if (candidate.flags & meaning) { + return candidateName; + } + + if (candidate.flags & SymbolFlags.Alias) { + const alias = tryResolveAlias(candidate); + if (alias && alias.flags & meaning) { + return candidateName; + } + } + + return undefined; + } + } + + function markPropertyAsReferenced(prop: Symbol, nodeForCheckWriteOnly: Node | undefined, isSelfTypeAccess: boolean) { + const valueDeclaration = prop && (prop.flags & SymbolFlags.ClassMember) && prop.valueDeclaration; + if (!valueDeclaration) { + return; + } + const hasPrivateModifier = hasEffectiveModifier(valueDeclaration, ModifierFlags.Private); + const hasPrivateIdentifier = prop.valueDeclaration && isNamedDeclaration(prop.valueDeclaration) && isPrivateIdentifier(prop.valueDeclaration.name); + if (!hasPrivateModifier && !hasPrivateIdentifier) { + return; + } + if (nodeForCheckWriteOnly && isWriteOnlyAccess(nodeForCheckWriteOnly) && !(prop.flags & SymbolFlags.SetAccessor)) { + return; + } + if (isSelfTypeAccess) { + // Find any FunctionLikeDeclaration because those create a new 'this' binding. But this should only matter for methods (or getters/setters). + const containingMethod = findAncestor(nodeForCheckWriteOnly, isFunctionLikeDeclaration); + if (containingMethod && containingMethod.symbol === prop) { + return; + } + } + + (getCheckFlags(prop) & CheckFlags.Instantiated ? getSymbolLinks(prop).target : prop)!.isReferenced = SymbolFlags.All; + } + + function isSelfTypeAccess(name: Expression | QualifiedName, parent: Symbol | undefined) { + return name.kind === SyntaxKind.ThisKeyword + || !!parent && isEntityNameExpression(name) && parent === getResolvedSymbol(getFirstIdentifier(name)); + } + + function isValidPropertyAccess(node: PropertyAccessExpression | QualifiedName | ImportTypeNode, propertyName: __String): boolean { + switch (node.kind) { + case SyntaxKind.PropertyAccessExpression: + return isValidPropertyAccessWithType(node, node.expression.kind === SyntaxKind.SuperKeyword, propertyName, getWidenedType(checkExpression(node.expression))); + case SyntaxKind.QualifiedName: + return isValidPropertyAccessWithType(node, /*isSuper*/ false, propertyName, getWidenedType(checkExpression(node.left))); + case SyntaxKind.ImportType: + return isValidPropertyAccessWithType(node, /*isSuper*/ false, propertyName, getTypeFromTypeNode(node)); + } + } + + /** + * Checks if an existing property access is valid for completions purposes. + * @param node a property access-like node where we want to check if we can access a property. + * This node does not need to be an access of the property we are checking. + * e.g. in completions, this node will often be an incomplete property access node, as in `foo.`. + * Besides providing a location (i.e. scope) used to check property accessibility, we use this node for + * computing whether this is a `super` property access. + * @param type the type whose property we are checking. + * @param property the accessed property's symbol. + */ + function isValidPropertyAccessForCompletions(node: PropertyAccessExpression | ImportTypeNode | QualifiedName, type: Type, property: Symbol): boolean { + return isPropertyAccessible(node, node.kind === SyntaxKind.PropertyAccessExpression && node.expression.kind === SyntaxKind.SuperKeyword, /*isWrite*/ false, type, property); + // Previously we validated the 'this' type of methods but this adversely affected performance. See #31377 for more context. + } + + function isValidPropertyAccessWithType( + node: PropertyAccessExpression | QualifiedName | ImportTypeNode, + isSuper: boolean, + propertyName: __String, + type: Type, + ): boolean { + // Short-circuiting for improved performance. + if (isTypeAny(type)) { + return true; + } + + const prop = getPropertyOfType(type, propertyName); + return !!prop && isPropertyAccessible(node, isSuper, /*isWrite*/ false, type, prop); + } + + /** + * Checks if a property can be accessed in a location. + * The location is given by the `node` parameter. + * The node does not need to be a property access. + * @param node location where to check property accessibility + * @param isSuper whether to consider this a `super` property access, e.g. `super.foo`. + * @param isWrite whether this is a write access, e.g. `++foo.x`. + * @param containingType type where the property comes from. + * @param property property symbol. + */ + function isPropertyAccessible( + node: Node, + isSuper: boolean, + isWrite: boolean, + containingType: Type, + property: Symbol, + ): boolean { + // Short-circuiting for improved performance. + if (isTypeAny(containingType)) { + return true; + } + + // A #private property access in an optional chain is an error dealt with by the parser. + // The checker does not check for it, so we need to do our own check here. + if (property.valueDeclaration && isPrivateIdentifierClassElementDeclaration(property.valueDeclaration)) { + const declClass = getContainingClass(property.valueDeclaration); + return !isOptionalChain(node) && !!findAncestor(node, parent => parent === declClass); + } + + return checkPropertyAccessibilityAtLocation(node, isSuper, isWrite, containingType, property); + } + + /** + * Return the symbol of the for-in variable declared or referenced by the given for-in statement. + */ + function getForInVariableSymbol(node: ForInStatement): Symbol | undefined { + const initializer = node.initializer; + if (initializer.kind === SyntaxKind.VariableDeclarationList) { + const variable = (initializer as VariableDeclarationList).declarations[0]; + if (variable && !isBindingPattern(variable.name)) { + return getSymbolOfDeclaration(variable); + } + } + else if (initializer.kind === SyntaxKind.Identifier) { + return getResolvedSymbol(initializer as Identifier); + } + return undefined; + } + + /** + * Return true if the given type is considered to have numeric property names. + */ + function hasNumericPropertyNames(type: Type) { + return getIndexInfosOfType(type).length === 1 && !!getIndexInfoOfType(type, numberType); + } + + /** + * Return true if given node is an expression consisting of an identifier (possibly parenthesized) + * that references a for-in variable for an object with numeric property names. + */ + function isForInVariableForNumericPropertyNames(expr: Expression) { + const e = skipParentheses(expr); + if (e.kind === SyntaxKind.Identifier) { + const symbol = getResolvedSymbol(e as Identifier); + if (symbol.flags & SymbolFlags.Variable) { + let child: Node = expr; + let node = expr.parent; + while (node) { + if ( + node.kind === SyntaxKind.ForInStatement && + child === (node as ForInStatement).statement && + getForInVariableSymbol(node as ForInStatement) === symbol && + hasNumericPropertyNames(getTypeOfExpression((node as ForInStatement).expression)) + ) { + return true; + } + child = node; + node = node.parent; + } + } + } + return false; + } + + function checkIndexedAccess(node: ElementAccessExpression, checkMode: CheckMode | undefined): Type { + return node.flags & NodeFlags.OptionalChain ? checkElementAccessChain(node as ElementAccessChain, checkMode) : + checkElementAccessExpression(node, checkNonNullExpression(node.expression), checkMode); + } + + function checkElementAccessChain(node: ElementAccessChain, checkMode: CheckMode | undefined) { + const exprType = checkExpression(node.expression); + const nonOptionalType = getOptionalExpressionType(exprType, node.expression); + return propagateOptionalTypeMarker(checkElementAccessExpression(node, checkNonNullType(nonOptionalType, node.expression), checkMode), node, nonOptionalType !== exprType); + } + + function checkElementAccessExpression(node: ElementAccessExpression, exprType: Type, checkMode: CheckMode | undefined): Type { + const objectType = getAssignmentTargetKind(node) !== AssignmentKind.None || isMethodAccessForCall(node) ? getWidenedType(exprType) : exprType; + const indexExpression = node.argumentExpression; + const indexType = checkExpression(indexExpression); + + if (isErrorType(objectType) || objectType === silentNeverType) { + return objectType; + } + + if (isConstEnumObjectType(objectType) && !isStringLiteralLike(indexExpression)) { + error(indexExpression, Diagnostics.A_const_enum_member_can_only_be_accessed_using_a_string_literal); + return errorType; + } + + const effectiveIndexType = isForInVariableForNumericPropertyNames(indexExpression) ? numberType : indexType; + const assignmentTargetKind = getAssignmentTargetKind(node); + let accessFlags: AccessFlags; + if (assignmentTargetKind === AssignmentKind.None) { + accessFlags = AccessFlags.ExpressionPosition; + } + else { + accessFlags = AccessFlags.Writing | (isGenericObjectType(objectType) && !isThisTypeParameter(objectType) ? AccessFlags.NoIndexSignatures : 0); + if (assignmentTargetKind === AssignmentKind.Compound) { + accessFlags |= AccessFlags.ExpressionPosition; + } + } + const indexedAccessType = getIndexedAccessTypeOrUndefined(objectType, effectiveIndexType, accessFlags, node) || errorType; + return checkIndexedAccessIndexType(getFlowTypeOfAccessExpression(node, getNodeLinks(node).resolvedSymbol, indexedAccessType, indexExpression, checkMode), node); + } + + function callLikeExpressionMayHaveTypeArguments(node: CallLikeExpression): node is CallExpression | NewExpression | TaggedTemplateExpression | JsxOpeningElement { + return isCallOrNewExpression(node) || isTaggedTemplateExpression(node) || isJsxOpeningLikeElement(node); + } + + function resolveUntypedCall(node: CallLikeExpression): Signature { + if (callLikeExpressionMayHaveTypeArguments(node)) { + // Check type arguments even though we will give an error that untyped calls may not accept type arguments. + // This gets us diagnostics for the type arguments and marks them as referenced. + forEach(node.typeArguments, checkSourceElement); + } + + if (node.kind === SyntaxKind.TaggedTemplateExpression) { + checkExpression(node.template); + } + else if (isJsxOpeningLikeElement(node)) { + checkExpression(node.attributes); + } + else if (isBinaryExpression(node)) { + checkExpression(node.left); + } + else if (isCallOrNewExpression(node)) { + forEach(node.arguments, argument => { + checkExpression(argument); + }); + } + return anySignature; + } + + function resolveErrorCall(node: CallLikeExpression): Signature { + resolveUntypedCall(node); + return unknownSignature; + } + + // Re-order candidate signatures into the result array. Assumes the result array to be empty. + // The candidate list orders groups in reverse, but within a group signatures are kept in declaration order + // A nit here is that we reorder only signatures that belong to the same symbol, + // so order how inherited signatures are processed is still preserved. + // interface A { (x: string): void } + // interface B extends A { (x: 'foo'): string } + // const b: B; + // b('foo') // <- here overloads should be processed as [(x:'foo'): string, (x: string): void] + function reorderCandidates(signatures: readonly Signature[], result: Signature[], callChainFlags: SignatureFlags): void { + let lastParent: Node | undefined; + let lastSymbol: Symbol | undefined; + let cutoffIndex = 0; + let index: number | undefined; + let specializedIndex = -1; + let spliceIndex: number; + Debug.assert(!result.length); + for (const signature of signatures) { + const symbol = signature.declaration && getSymbolOfDeclaration(signature.declaration); + const parent = signature.declaration && signature.declaration.parent; + if (!lastSymbol || symbol === lastSymbol) { + if (lastParent && parent === lastParent) { + index = index! + 1; + } + else { + lastParent = parent; + index = cutoffIndex; + } + } + else { + // current declaration belongs to a different symbol + // set cutoffIndex so re-orderings in the future won't change result set from 0 to cutoffIndex + index = cutoffIndex = result.length; + lastParent = parent; + } + lastSymbol = symbol; + + // specialized signatures always need to be placed before non-specialized signatures regardless + // of the cutoff position; see GH#1133 + if (signatureHasLiteralTypes(signature)) { + specializedIndex++; + spliceIndex = specializedIndex; + // The cutoff index always needs to be greater than or equal to the specialized signature index + // in order to prevent non-specialized signatures from being added before a specialized + // signature. + cutoffIndex++; + } + else { + spliceIndex = index; + } + + result.splice(spliceIndex, 0, callChainFlags ? getOptionalCallSignature(signature, callChainFlags) : signature); + } + } + + function isSpreadArgument(arg: Expression | undefined): arg is Expression { + return !!arg && (arg.kind === SyntaxKind.SpreadElement || arg.kind === SyntaxKind.SyntheticExpression && (arg as SyntheticExpression).isSpread); + } + + function getSpreadArgumentIndex(args: readonly Expression[]): number { + return findIndex(args, isSpreadArgument); + } + + function acceptsVoid(t: Type): boolean { + return !!(t.flags & TypeFlags.Void); + } + + function acceptsVoidUndefinedUnknownOrAny(t: Type): boolean { + return !!(t.flags & (TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Unknown | TypeFlags.Any)); + } + + function hasCorrectArity(node: CallLikeExpression, args: readonly Expression[], signature: Signature, signatureHelpTrailingComma = false) { + let argCount: number; + let callIsIncomplete = false; // In incomplete call we want to be lenient when we have too few arguments + let effectiveParameterCount = getParameterCount(signature); + let effectiveMinimumArguments = getMinArgumentCount(signature); + + if (node.kind === SyntaxKind.TaggedTemplateExpression) { + argCount = args.length; + if (node.template.kind === SyntaxKind.TemplateExpression) { + // If a tagged template expression lacks a tail literal, the call is incomplete. + // Specifically, a template only can end in a TemplateTail or a Missing literal. + const lastSpan = last(node.template.templateSpans); // we should always have at least one span. + callIsIncomplete = nodeIsMissing(lastSpan.literal) || !!lastSpan.literal.isUnterminated; + } + else { + // If the template didn't end in a backtick, or its beginning occurred right prior to EOF, + // then this might actually turn out to be a TemplateHead in the future; + // so we consider the call to be incomplete. + const templateLiteral = node.template as LiteralExpression; + Debug.assert(templateLiteral.kind === SyntaxKind.NoSubstitutionTemplateLiteral); + callIsIncomplete = !!templateLiteral.isUnterminated; + } + } + else if (node.kind === SyntaxKind.Decorator) { + argCount = getDecoratorArgumentCount(node, signature); + } + else if (node.kind === SyntaxKind.BinaryExpression) { + argCount = 1; + } + else if (isJsxOpeningLikeElement(node)) { + callIsIncomplete = node.attributes.end === node.end; + if (callIsIncomplete) { + return true; + } + argCount = effectiveMinimumArguments === 0 ? args.length : 1; + effectiveParameterCount = args.length === 0 ? effectiveParameterCount : 1; // class may have argumentless ctor functions - still resolve ctor and compare vs props member type + effectiveMinimumArguments = Math.min(effectiveMinimumArguments, 1); // sfc may specify context argument - handled by framework and not typechecked + } + else if (!node.arguments) { + // This only happens when we have something of the form: 'new C' + Debug.assert(node.kind === SyntaxKind.NewExpression); + return getMinArgumentCount(signature) === 0; + } + else { + argCount = signatureHelpTrailingComma ? args.length + 1 : args.length; + + // If we are missing the close parenthesis, the call is incomplete. + callIsIncomplete = node.arguments.end === node.end; + + // If a spread argument is present, check that it corresponds to a rest parameter or at least that it's in the valid range. + const spreadArgIndex = getSpreadArgumentIndex(args); + if (spreadArgIndex >= 0) { + return spreadArgIndex >= getMinArgumentCount(signature) && (hasEffectiveRestParameter(signature) || spreadArgIndex < getParameterCount(signature)); + } + } + + // Too many arguments implies incorrect arity. + if (!hasEffectiveRestParameter(signature) && argCount > effectiveParameterCount) { + return false; + } + + // If the call is incomplete, we should skip the lower bound check. + // JSX signatures can have extra parameters provided by the library which we don't check + if (callIsIncomplete || argCount >= effectiveMinimumArguments) { + return true; + } + for (let i = argCount; i < effectiveMinimumArguments; i++) { + const type = getTypeAtPosition(signature, i); + if (filterType(type, isInJSFile(node) && !strictNullChecks ? acceptsVoidUndefinedUnknownOrAny : acceptsVoid).flags & TypeFlags.Never) { + return false; + } + } + return true; + } + + function hasCorrectTypeArgumentArity(signature: Signature, typeArguments: NodeArray | undefined) { + // If the user supplied type arguments, but the number of type arguments does not match + // the declared number of type parameters, the call has an incorrect arity. + const numTypeParameters = length(signature.typeParameters); + const minTypeArgumentCount = getMinTypeArgumentCount(signature.typeParameters); + return !some(typeArguments) || + (typeArguments.length >= minTypeArgumentCount && typeArguments.length <= numTypeParameters); + } + + function isInstantiatedGenericParameter(signature: Signature, pos: number) { + let type; + return !!(signature.target && (type = tryGetTypeAtPosition(signature.target, pos)) && isGenericType(type)); + } + + // If type has a single call signature and no other members, return that signature. Otherwise, return undefined. + function getSingleCallSignature(type: Type): Signature | undefined { + return getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ false); + } + + function getSingleCallOrConstructSignature(type: Type): Signature | undefined { + return getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ false) || + getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ false); + } + + function getSingleSignature(type: Type, kind: SignatureKind, allowMembers: boolean): Signature | undefined { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + if (allowMembers || resolved.properties.length === 0 && resolved.indexInfos.length === 0) { + if (kind === SignatureKind.Call && resolved.callSignatures.length === 1 && resolved.constructSignatures.length === 0) { + return resolved.callSignatures[0]; + } + if (kind === SignatureKind.Construct && resolved.constructSignatures.length === 1 && resolved.callSignatures.length === 0) { + return resolved.constructSignatures[0]; + } + } + } + return undefined; + } + + // Instantiate a generic signature in the context of a non-generic signature (section 3.8.5 in TypeScript spec) + function instantiateSignatureInContextOf(signature: Signature, contextualSignature: Signature, inferenceContext?: InferenceContext, compareTypes?: TypeComparer): Signature { + const context = createInferenceContext(signature.typeParameters!, signature, InferenceFlags.None, compareTypes); + // We clone the inferenceContext to avoid fixing. For example, when the source signature is (x: T) => T[] and + // the contextual signature is (...args: A) => B, we want to infer the element type of A's constraint (say 'any') + // for T but leave it possible to later infer '[any]' back to A. + const restType = getEffectiveRestType(contextualSignature); + const mapper = inferenceContext && (restType && restType.flags & TypeFlags.TypeParameter ? inferenceContext.nonFixingMapper : inferenceContext.mapper); + const sourceSignature = mapper ? instantiateSignature(contextualSignature, mapper) : contextualSignature; + applyToParameterTypes(sourceSignature, signature, (source, target) => { + // Type parameters from outer context referenced by source type are fixed by instantiation of the source type + inferTypes(context.inferences, source, target); + }); + if (!inferenceContext) { + applyToReturnTypes(contextualSignature, signature, (source, target) => { + inferTypes(context.inferences, source, target, InferencePriority.ReturnType); + }); + } + return getSignatureInstantiation(signature, getInferredTypes(context), isInJSFile(contextualSignature.declaration)); + } + + function inferJsxTypeArguments(node: JsxOpeningLikeElement, signature: Signature, checkMode: CheckMode, context: InferenceContext): Type[] { + const paramType = getEffectiveFirstArgumentForJsxSignature(signature, node); + const checkAttrType = checkExpressionWithContextualType(node.attributes, paramType, context, checkMode); + inferTypes(context.inferences, checkAttrType, paramType); + return getInferredTypes(context); + } + + function getThisArgumentType(thisArgumentNode: Expression | undefined) { + if (!thisArgumentNode) { + return voidType; + } + const thisArgumentType = checkExpression(thisArgumentNode); + return isRightSideOfInstanceofExpression(thisArgumentNode) ? thisArgumentType : + isOptionalChainRoot(thisArgumentNode.parent) ? getNonNullableType(thisArgumentType) : + isOptionalChain(thisArgumentNode.parent) ? removeOptionalTypeMarker(thisArgumentType) : + thisArgumentType; + } + + function inferTypeArguments(node: CallLikeExpression, signature: Signature, args: readonly Expression[], checkMode: CheckMode, context: InferenceContext): Type[] { + if (isJsxOpeningLikeElement(node)) { + return inferJsxTypeArguments(node, signature, checkMode, context); + } + + // If a contextual type is available, infer from that type to the return type of the call expression. For + // example, given a 'function wrap(cb: (x: T) => U): (x: T) => U' and a call expression + // 'let f: (x: string) => number = wrap(s => s.length)', we infer from the declared type of 'f' to the + // return type of 'wrap'. + if (node.kind !== SyntaxKind.Decorator && node.kind !== SyntaxKind.BinaryExpression) { + const skipBindingPatterns = every(signature.typeParameters, p => !!getDefaultFromTypeParameter(p)); + const contextualType = getContextualType(node, skipBindingPatterns ? ContextFlags.SkipBindingPatterns : ContextFlags.None); + if (contextualType) { + const inferenceTargetType = getReturnTypeOfSignature(signature); + if (couldContainTypeVariables(inferenceTargetType)) { + const outerContext = getInferenceContext(node); + const isFromBindingPattern = !skipBindingPatterns && getContextualType(node, ContextFlags.SkipBindingPatterns) !== contextualType; + // A return type inference from a binding pattern can be used in instantiating the contextual + // type of an argument later in inference, but cannot stand on its own as the final return type. + // It is incorporated into `context.returnMapper` which is used in `instantiateContextualType`, + // but doesn't need to go into `context.inferences`. This allows a an array binding pattern to + // produce a tuple for `T` in + // declare function f(cb: () => T): T; + // const [e1, e2, e3] = f(() => [1, "hi", true]); + // but does not produce any inference for `T` in + // declare function f(): T; + // const [e1, e2, e3] = f(); + if (!isFromBindingPattern) { + // We clone the inference context to avoid disturbing a resolution in progress for an + // outer call expression. Effectively we just want a snapshot of whatever has been + // inferred for any outer call expression so far. + const outerMapper = getMapperFromContext(cloneInferenceContext(outerContext, InferenceFlags.NoDefault)); + const instantiatedType = instantiateType(contextualType, outerMapper); + // If the contextual type is a generic function type with a single call signature, we + // instantiate the type with its own type parameters and type arguments. This ensures that + // the type parameters are not erased to type any during type inference such that they can + // be inferred as actual types from the contextual type. For example: + // declare function arrayMap(f: (x: T) => U): (a: T[]) => U[]; + // const boxElements: (a: A[]) => { value: A }[] = arrayMap(value => ({ value })); + // Above, the type of the 'value' parameter is inferred to be 'A'. + const contextualSignature = getSingleCallSignature(instantiatedType); + const inferenceSourceType = contextualSignature && contextualSignature.typeParameters ? + getOrCreateTypeFromSignature(getSignatureInstantiationWithoutFillingInTypeArguments(contextualSignature, contextualSignature.typeParameters)) : + instantiatedType; + // Inferences made from return types have lower priority than all other inferences. + inferTypes(context.inferences, inferenceSourceType, inferenceTargetType, InferencePriority.ReturnType); + } + // Create a type mapper for instantiating generic contextual types using the inferences made + // from the return type. We need a separate inference pass here because (a) instantiation of + // the source type uses the outer context's return mapper (which excludes inferences made from + // outer arguments), and (b) we don't want any further inferences going into this context. + const returnContext = createInferenceContext(signature.typeParameters!, signature, context.flags); + const returnSourceType = instantiateType(contextualType, outerContext && outerContext.returnMapper); + inferTypes(returnContext.inferences, returnSourceType, inferenceTargetType); + context.returnMapper = some(returnContext.inferences, hasInferenceCandidates) ? getMapperFromContext(cloneInferredPartOfContext(returnContext)) : undefined; + } + } + } + + const restType = getNonArrayRestType(signature); + const argCount = restType ? Math.min(getParameterCount(signature) - 1, args.length) : args.length; + if (restType && restType.flags & TypeFlags.TypeParameter) { + const info = find(context.inferences, info => info.typeParameter === restType); + if (info) { + info.impliedArity = findIndex(args, isSpreadArgument, argCount) < 0 ? args.length - argCount : undefined; + } + } + + const thisType = getThisTypeOfSignature(signature); + if (thisType && couldContainTypeVariables(thisType)) { + const thisArgumentNode = getThisArgumentOfCall(node); + inferTypes(context.inferences, getThisArgumentType(thisArgumentNode), thisType); + } + + for (let i = 0; i < argCount; i++) { + const arg = args[i]; + if (arg.kind !== SyntaxKind.OmittedExpression) { + const paramType = getTypeAtPosition(signature, i); + if (couldContainTypeVariables(paramType)) { + const argType = checkExpressionWithContextualType(arg, paramType, context, checkMode); + inferTypes(context.inferences, argType, paramType); + } + } + } + + if (restType && couldContainTypeVariables(restType)) { + const spreadType = getSpreadArgumentType(args, argCount, args.length, restType, context, checkMode); + inferTypes(context.inferences, spreadType, restType); + } + + return getInferredTypes(context); + } + + function getMutableArrayOrTupleType(type: Type) { + return type.flags & TypeFlags.Union ? mapType(type, getMutableArrayOrTupleType) : + type.flags & TypeFlags.Any || isMutableArrayOrTuple(getBaseConstraintOfType(type) || type) ? type : + isTupleType(type) ? createTupleType(getElementTypes(type), type.target.elementFlags, /*readonly*/ false, type.target.labeledElementDeclarations) : + createTupleType([type], [ElementFlags.Variadic]); + } + + function getSpreadArgumentType(args: readonly Expression[], index: number, argCount: number, restType: Type, context: InferenceContext | undefined, checkMode: CheckMode) { + const inConstContext = isConstTypeVariable(restType); + + if (index >= argCount - 1) { + const arg = args[argCount - 1]; + if (isSpreadArgument(arg)) { + // We are inferring from a spread expression in the last argument position, i.e. both the parameter + // and the argument are ...x forms. + const spreadType = arg.kind === SyntaxKind.SyntheticExpression ? (arg as SyntheticExpression).type : + checkExpressionWithContextualType((arg as SpreadElement).expression, restType, context, checkMode); + + if (isArrayLikeType(spreadType)) { + return getMutableArrayOrTupleType(spreadType); + } + + return createArrayType(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, arg.kind === SyntaxKind.SpreadElement ? (arg as SpreadElement).expression : arg), inConstContext); + } + } + const types = []; + const flags = []; + const names = []; + for (let i = index; i < argCount; i++) { + const arg = args[i]; + if (isSpreadArgument(arg)) { + const spreadType = arg.kind === SyntaxKind.SyntheticExpression ? (arg as SyntheticExpression).type : checkExpression((arg as SpreadElement).expression); + if (isArrayLikeType(spreadType)) { + types.push(spreadType); + flags.push(ElementFlags.Variadic); + } + else { + types.push(checkIteratedTypeOrElementType(IterationUse.Spread, spreadType, undefinedType, arg.kind === SyntaxKind.SpreadElement ? (arg as SpreadElement).expression : arg)); + flags.push(ElementFlags.Rest); + } + } + else { + const contextualType = isTupleType(restType) ? + getContextualTypeForElementExpression(restType, i - index, argCount - index) || unknownType : + getIndexedAccessType(restType, getNumberLiteralType(i - index), AccessFlags.Contextual); + const argType = checkExpressionWithContextualType(arg, contextualType, context, checkMode); + const hasPrimitiveContextualType = inConstContext || maybeTypeOfKind(contextualType, TypeFlags.Primitive | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping); + types.push(hasPrimitiveContextualType ? getRegularTypeOfLiteralType(argType) : getWidenedLiteralType(argType)); + flags.push(ElementFlags.Required); + } + if (arg.kind === SyntaxKind.SyntheticExpression && (arg as SyntheticExpression).tupleNameSource) { + names.push((arg as SyntheticExpression).tupleNameSource!); + } + else { + names.push(undefined); + } + } + return createTupleType(types, flags, inConstContext && !someType(restType, isMutableArrayLikeType), names); + } + + function checkTypeArguments(signature: Signature, typeArgumentNodes: readonly TypeNode[], reportErrors: boolean, headMessage?: DiagnosticMessage): Type[] | undefined { + const isJavascript = isInJSFile(signature.declaration); + const typeParameters = signature.typeParameters!; + const typeArgumentTypes = fillMissingTypeArguments(map(typeArgumentNodes, getTypeFromTypeNode), typeParameters, getMinTypeArgumentCount(typeParameters), isJavascript); + let mapper: TypeMapper | undefined; + for (let i = 0; i < typeArgumentNodes.length; i++) { + Debug.assert(typeParameters[i] !== undefined, "Should not call checkTypeArguments with too many type arguments"); + const constraint = getConstraintOfTypeParameter(typeParameters[i]); + if (constraint) { + const errorInfo = reportErrors && headMessage ? (() => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Type_0_does_not_satisfy_the_constraint_1)) : undefined; + const typeArgumentHeadMessage = headMessage || Diagnostics.Type_0_does_not_satisfy_the_constraint_1; + if (!mapper) { + mapper = createTypeMapper(typeParameters, typeArgumentTypes); + } + const typeArgument = typeArgumentTypes[i]; + if ( + !checkTypeAssignableTo( + typeArgument, + getTypeWithThisArgument(instantiateType(constraint, mapper), typeArgument), + reportErrors ? typeArgumentNodes[i] : undefined, + typeArgumentHeadMessage, + errorInfo, + ) + ) { + return undefined; + } + } + } + return typeArgumentTypes; + } + + function getJsxReferenceKind(node: JsxOpeningLikeElement): JsxReferenceKind { + if (isJsxIntrinsicTagName(node.tagName)) { + return JsxReferenceKind.Mixed; + } + const tagType = getApparentType(checkExpression(node.tagName)); + if (length(getSignaturesOfType(tagType, SignatureKind.Construct))) { + return JsxReferenceKind.Component; + } + if (length(getSignaturesOfType(tagType, SignatureKind.Call))) { + return JsxReferenceKind.Function; + } + return JsxReferenceKind.Mixed; + } + + /** + * Check if the given signature can possibly be a signature called by the JSX opening-like element. + * @param node a JSX opening-like element we are trying to figure its call signature + * @param signature a candidate signature we are trying whether it is a call signature + * @param relation a relationship to check parameter and argument type + */ + function checkApplicableSignatureForJsxOpeningLikeElement( + node: JsxOpeningLikeElement, + signature: Signature, + relation: Map, + checkMode: CheckMode, + reportErrors: boolean, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; }, + ) { + // Stateless function components can have maximum of three arguments: "props", "context", and "updater". + // However "context" and "updater" are implicit and can't be specify by users. Only the first parameter, props, + // can be specified by users through attributes property. + const paramType = getEffectiveFirstArgumentForJsxSignature(signature, node); + const attributesType = checkExpressionWithContextualType(node.attributes, paramType, /*inferenceContext*/ undefined, checkMode); + const checkAttributesType = checkMode & CheckMode.SkipContextSensitive ? getRegularTypeOfObjectLiteral(attributesType) : attributesType; + return checkTagNameDoesNotExpectTooManyArguments() && checkTypeRelatedToAndOptionallyElaborate( + checkAttributesType, + paramType, + relation, + reportErrors ? node.tagName : undefined, + node.attributes, + /*headMessage*/ undefined, + containingMessageChain, + errorOutputContainer, + ); + + function checkTagNameDoesNotExpectTooManyArguments(): boolean { + if (getJsxNamespaceContainerForImplicitImport(node)) { + return true; // factory is implicitly jsx/jsxdev - assume it fits the bill, since we don't strongly look for the jsx/jsxs/jsxDEV factory APIs anywhere else (at least not yet) + } + const tagType = (isJsxOpeningElement(node) || isJsxSelfClosingElement(node)) && !(isJsxIntrinsicTagName(node.tagName) || isJsxNamespacedName(node.tagName)) ? checkExpression(node.tagName) : undefined; + if (!tagType) { + return true; + } + const tagCallSignatures = getSignaturesOfType(tagType, SignatureKind.Call); + if (!length(tagCallSignatures)) { + return true; + } + const factory = getJsxFactoryEntity(node); + if (!factory) { + return true; + } + const factorySymbol = resolveEntityName(factory, SymbolFlags.Value, /*ignoreErrors*/ true, /*dontResolveAlias*/ false, node); + if (!factorySymbol) { + return true; + } + + const factoryType = getTypeOfSymbol(factorySymbol); + const callSignatures = getSignaturesOfType(factoryType, SignatureKind.Call); + if (!length(callSignatures)) { + return true; + } + + let hasFirstParamSignatures = false; + let maxParamCount = 0; + // Check that _some_ first parameter expects a FC-like thing, and that some overload of the SFC expects an acceptable number of arguments + for (const sig of callSignatures) { + const firstparam = getTypeAtPosition(sig, 0); + const signaturesOfParam = getSignaturesOfType(firstparam, SignatureKind.Call); + if (!length(signaturesOfParam)) continue; + for (const paramSig of signaturesOfParam) { + hasFirstParamSignatures = true; + if (hasEffectiveRestParameter(paramSig)) { + return true; // some signature has a rest param, so function components can have an arbitrary number of arguments + } + const paramCount = getParameterCount(paramSig); + if (paramCount > maxParamCount) { + maxParamCount = paramCount; + } + } + } + if (!hasFirstParamSignatures) { + // Not a single signature had a first parameter which expected a signature - for back compat, and + // to guard against generic factories which won't have signatures directly, do not error + return true; + } + let absoluteMinArgCount = Infinity; + for (const tagSig of tagCallSignatures) { + const tagRequiredArgCount = getMinArgumentCount(tagSig); + if (tagRequiredArgCount < absoluteMinArgCount) { + absoluteMinArgCount = tagRequiredArgCount; + } + } + if (absoluteMinArgCount <= maxParamCount) { + return true; // some signature accepts the number of arguments the function component provides + } + + if (reportErrors) { + const diag = createDiagnosticForNode(node.tagName, Diagnostics.Tag_0_expects_at_least_1_arguments_but_the_JSX_factory_2_provides_at_most_3, entityNameToString(node.tagName), absoluteMinArgCount, entityNameToString(factory), maxParamCount); + const tagNameDeclaration = getSymbolAtLocation(node.tagName)?.valueDeclaration; + if (tagNameDeclaration) { + addRelatedInfo(diag, createDiagnosticForNode(tagNameDeclaration, Diagnostics._0_is_declared_here, entityNameToString(node.tagName))); + } + if (errorOutputContainer && errorOutputContainer.skipLogging) { + (errorOutputContainer.errors || (errorOutputContainer.errors = [])).push(diag); + } + if (!errorOutputContainer.skipLogging) { + diagnostics.add(diag); + } + } + return false; + } + } + + function getEffectiveCheckNode(argument: Expression): Expression { + argument = skipParentheses(argument); + return isSatisfiesExpression(argument) ? skipParentheses(argument.expression) : argument; + } + + function getSignatureApplicabilityError( + node: CallLikeExpression, + args: readonly Expression[], + signature: Signature, + relation: Map, + checkMode: CheckMode, + reportErrors: boolean, + containingMessageChain: (() => DiagnosticMessageChain | undefined) | undefined, + inferenceContext: InferenceContext | undefined, + ): readonly Diagnostic[] | undefined { + const errorOutputContainer: { errors?: Diagnostic[]; skipLogging?: boolean; } = { errors: undefined, skipLogging: true }; + if (isJsxOpeningLikeElement(node)) { + if (!checkApplicableSignatureForJsxOpeningLikeElement(node, signature, relation, checkMode, reportErrors, containingMessageChain, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "jsx should have errors when reporting errors"); + return errorOutputContainer.errors || emptyArray; + } + return undefined; + } + const thisType = getThisTypeOfSignature(signature); + if (thisType && thisType !== voidType && !(isNewExpression(node) || isCallExpression(node) && isSuperProperty(node.expression))) { + // If the called expression is not of the form `x.f` or `x["f"]`, then sourceType = voidType + // If the signature's 'this' type is voidType, then the check is skipped -- anything is compatible. + // If the expression is a new expression or super call expression, then the check is skipped. + const thisArgumentNode = getThisArgumentOfCall(node); + const thisArgumentType = getThisArgumentType(thisArgumentNode); + const errorNode = reportErrors ? (thisArgumentNode || node) : undefined; + const headMessage = Diagnostics.The_this_context_of_type_0_is_not_assignable_to_method_s_this_of_type_1; + if (!checkTypeRelatedTo(thisArgumentType, thisType, relation, errorNode, headMessage, containingMessageChain, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "this parameter should have errors when reporting errors"); + return errorOutputContainer.errors || emptyArray; + } + } + const headMessage = Diagnostics.Argument_of_type_0_is_not_assignable_to_parameter_of_type_1; + const restType = getNonArrayRestType(signature); + const argCount = restType ? Math.min(getParameterCount(signature) - 1, args.length) : args.length; + for (let i = 0; i < argCount; i++) { + const arg = args[i]; + if (arg.kind !== SyntaxKind.OmittedExpression) { + const paramType = getTypeAtPosition(signature, i); + const argType = checkExpressionWithContextualType(arg, paramType, /*inferenceContext*/ undefined, checkMode); + // If one or more arguments are still excluded (as indicated by CheckMode.SkipContextSensitive), + // we obtain the regular type of any object literal arguments because we may not have inferred complete + // parameter types yet and therefore excess property checks may yield false positives (see #17041). + const regularArgType = checkMode & CheckMode.SkipContextSensitive ? getRegularTypeOfObjectLiteral(argType) : argType; + // If this was inferred under a given inference context, we may need to instantiate the expression type to finish resolving + // the type variables in the expression. + const checkArgType = inferenceContext ? instantiateType(regularArgType, inferenceContext.nonFixingMapper) : regularArgType; + const effectiveCheckArgumentNode = getEffectiveCheckNode(arg); + if (!checkTypeRelatedToAndOptionallyElaborate(checkArgType, paramType, relation, reportErrors ? effectiveCheckArgumentNode : undefined, effectiveCheckArgumentNode, headMessage, containingMessageChain, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "parameter should have errors when reporting errors"); + maybeAddMissingAwaitInfo(arg, checkArgType, paramType); + return errorOutputContainer.errors || emptyArray; + } + } + } + if (restType) { + const spreadType = getSpreadArgumentType(args, argCount, args.length, restType, /*context*/ undefined, checkMode); + const restArgCount = args.length - argCount; + const errorNode = !reportErrors ? undefined : + restArgCount === 0 ? node : + restArgCount === 1 ? getEffectiveCheckNode(args[argCount]) : + setTextRangePosEnd(createSyntheticExpression(node, spreadType), args[argCount].pos, args[args.length - 1].end); + if (!checkTypeRelatedTo(spreadType, restType, relation, errorNode, headMessage, /*containingMessageChain*/ undefined, errorOutputContainer)) { + Debug.assert(!reportErrors || !!errorOutputContainer.errors, "rest parameter should have errors when reporting errors"); + maybeAddMissingAwaitInfo(errorNode, spreadType, restType); + return errorOutputContainer.errors || emptyArray; + } + } + return undefined; + + function maybeAddMissingAwaitInfo(errorNode: Node | undefined, source: Type, target: Type) { + if (errorNode && reportErrors && errorOutputContainer.errors && errorOutputContainer.errors.length) { + // Bail if target is Promise-like---something else is wrong + if (getAwaitedTypeOfPromise(target)) { + return; + } + const awaitedTypeOfSource = getAwaitedTypeOfPromise(source); + if (awaitedTypeOfSource && isTypeRelatedTo(awaitedTypeOfSource, target, relation)) { + addRelatedInfo(errorOutputContainer.errors[0], createDiagnosticForNode(errorNode, Diagnostics.Did_you_forget_to_use_await)); + } + } + } + } + + /** + * Returns the this argument in calls like x.f(...) and x[f](...). Undefined otherwise. + */ + function getThisArgumentOfCall(node: CallLikeExpression): Expression | undefined { + if (node.kind === SyntaxKind.BinaryExpression) { + return node.right; + } + + const expression = node.kind === SyntaxKind.CallExpression ? node.expression : + node.kind === SyntaxKind.TaggedTemplateExpression ? node.tag : + node.kind === SyntaxKind.Decorator && !legacyDecorators ? node.expression : + undefined; + if (expression) { + const callee = skipOuterExpressions(expression); + if (isAccessExpression(callee)) { + return callee.expression; + } + } + } + + function createSyntheticExpression(parent: Node, type: Type, isSpread?: boolean, tupleNameSource?: ParameterDeclaration | NamedTupleMember) { + const result = parseNodeFactory.createSyntheticExpression(type, isSpread, tupleNameSource); + setTextRangeWorker(result, parent); + setParent(result, parent); + return result; + } + + /** + * Returns the effective arguments for an expression that works like a function invocation. + */ + function getEffectiveCallArguments(node: CallLikeExpression): readonly Expression[] { + if (node.kind === SyntaxKind.TaggedTemplateExpression) { + const template = node.template; + const args: Expression[] = [createSyntheticExpression(template, getGlobalTemplateStringsArrayType())]; + if (template.kind === SyntaxKind.TemplateExpression) { + forEach(template.templateSpans, span => { + args.push(span.expression); + }); + } + return args; + } + if (node.kind === SyntaxKind.Decorator) { + return getEffectiveDecoratorArguments(node); + } + if (node.kind === SyntaxKind.BinaryExpression) { + return [node.left]; + } + if (isJsxOpeningLikeElement(node)) { + return node.attributes.properties.length > 0 || (isJsxOpeningElement(node) && node.parent.children.length > 0) ? [node.attributes] : emptyArray; + } + const args = node.arguments || emptyArray; + const spreadIndex = getSpreadArgumentIndex(args); + if (spreadIndex >= 0) { + // Create synthetic arguments from spreads of tuple types. + const effectiveArgs = args.slice(0, spreadIndex); + for (let i = spreadIndex; i < args.length; i++) { + const arg = args[i]; + // We can call checkExpressionCached because spread expressions never have a contextual type. + const spreadType = arg.kind === SyntaxKind.SpreadElement && (flowLoopCount ? checkExpression((arg as SpreadElement).expression) : checkExpressionCached((arg as SpreadElement).expression)); + if (spreadType && isTupleType(spreadType)) { + forEach(getElementTypes(spreadType), (t, i) => { + const flags = spreadType.target.elementFlags[i]; + const syntheticArg = createSyntheticExpression(arg, flags & ElementFlags.Rest ? createArrayType(t) : t, !!(flags & ElementFlags.Variable), spreadType.target.labeledElementDeclarations?.[i]); + effectiveArgs.push(syntheticArg); + }); + } + else { + effectiveArgs.push(arg); + } + } + return effectiveArgs; + } + return args; + } + + /** + * Returns the synthetic argument list for a decorator invocation. + */ + function getEffectiveDecoratorArguments(node: Decorator): readonly Expression[] { + const expr = node.expression; + const signature = getDecoratorCallSignature(node); + if (signature) { + const args: Expression[] = []; + for (const param of signature.parameters) { + const type = getTypeOfSymbol(param); + args.push(createSyntheticExpression(expr, type)); + } + return args; + } + return Debug.fail(); + } + + /** + * Returns the argument count for a decorator node that works like a function invocation. + */ + function getDecoratorArgumentCount(node: Decorator, signature: Signature) { + return compilerOptions.experimentalDecorators ? + getLegacyDecoratorArgumentCount(node, signature) : + // Allow the runtime to oversupply arguments to an ES decorator as long as there's at least one parameter. + Math.min(Math.max(getParameterCount(signature), 1), 2); + } + + /** + * Returns the argument count for a decorator node that works like a function invocation. + */ + function getLegacyDecoratorArgumentCount(node: Decorator, signature: Signature) { + switch (node.parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + return 1; + case SyntaxKind.PropertyDeclaration: + return hasAccessorModifier(node.parent) ? 3 : 2; + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + // For decorators with only two parameters we supply only two arguments + return signature.parameters.length <= 2 ? 2 : 3; + case SyntaxKind.Parameter: + return 3; + default: + return Debug.fail(); + } + } + + function getDiagnosticSpanForCallNode(node: CallExpression) { + const sourceFile = getSourceFileOfNode(node); + const { start, length } = getErrorSpanForNode(sourceFile, isPropertyAccessExpression(node.expression) ? node.expression.name : node.expression); + return { start, length, sourceFile }; + } + + function getDiagnosticForCallNode(node: CallLikeExpression, message: DiagnosticMessage | DiagnosticMessageChain, ...args: DiagnosticArguments): DiagnosticWithLocation { + if (isCallExpression(node)) { + const { sourceFile, start, length } = getDiagnosticSpanForCallNode(node); + if ("message" in message) { // eslint-disable-line local/no-in-operator + return createFileDiagnostic(sourceFile, start, length, message, ...args); + } + return createDiagnosticForFileFromMessageChain(sourceFile, message); + } + else { + if ("message" in message) { // eslint-disable-line local/no-in-operator + return createDiagnosticForNode(node, message, ...args); + } + return createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node), node, message); + } + } + + function getErrorNodeForCallNode(callLike: CallLikeExpression): Node { + if (isCallOrNewExpression(callLike)) { + return isPropertyAccessExpression(callLike.expression) ? callLike.expression.name : callLike.expression; + } + if (isTaggedTemplateExpression(callLike)) { + return isPropertyAccessExpression(callLike.tag) ? callLike.tag.name : callLike.tag; + } + if (isJsxOpeningLikeElement(callLike)) { + return callLike.tagName; + } + return callLike; + } + + function isPromiseResolveArityError(node: CallLikeExpression) { + if (!isCallExpression(node) || !isIdentifier(node.expression)) return false; + + const symbol = resolveName(node.expression, node.expression.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + const decl = symbol?.valueDeclaration; + if (!decl || !isParameter(decl) || !isFunctionExpressionOrArrowFunction(decl.parent) || !isNewExpression(decl.parent.parent) || !isIdentifier(decl.parent.parent.expression)) { + return false; + } + + const globalPromiseSymbol = getGlobalPromiseConstructorSymbol(/*reportErrors*/ false); + if (!globalPromiseSymbol) return false; + + const constructorSymbol = getSymbolAtLocation(decl.parent.parent.expression, /*ignoreErrors*/ true); + return constructorSymbol === globalPromiseSymbol; + } + + function getArgumentArityError(node: CallLikeExpression, signatures: readonly Signature[], args: readonly Expression[], headMessage?: DiagnosticMessage) { + const spreadIndex = getSpreadArgumentIndex(args); + if (spreadIndex > -1) { + return createDiagnosticForNode(args[spreadIndex], Diagnostics.A_spread_argument_must_either_have_a_tuple_type_or_be_passed_to_a_rest_parameter); + } + let min = Number.POSITIVE_INFINITY; // smallest parameter count + let max = Number.NEGATIVE_INFINITY; // largest parameter count + let maxBelow = Number.NEGATIVE_INFINITY; // largest parameter count that is smaller than the number of arguments + let minAbove = Number.POSITIVE_INFINITY; // smallest parameter count that is larger than the number of arguments + + let closestSignature: Signature | undefined; + for (const sig of signatures) { + const minParameter = getMinArgumentCount(sig); + const maxParameter = getParameterCount(sig); + // smallest/largest parameter counts + if (minParameter < min) { + min = minParameter; + closestSignature = sig; + } + max = Math.max(max, maxParameter); + // shortest parameter count *longer than the call*/longest parameter count *shorter than the call* + if (minParameter < args.length && minParameter > maxBelow) maxBelow = minParameter; + if (args.length < maxParameter && maxParameter < minAbove) minAbove = maxParameter; + } + const hasRestParameter = some(signatures, hasEffectiveRestParameter); + const parameterRange = hasRestParameter ? min + : min < max ? min + "-" + max + : min; + const isVoidPromiseError = !hasRestParameter && parameterRange === 1 && args.length === 0 && isPromiseResolveArityError(node); + if (isVoidPromiseError && isInJSFile(node)) { + return getDiagnosticForCallNode(node, Diagnostics.Expected_1_argument_but_got_0_new_Promise_needs_a_JSDoc_hint_to_produce_a_resolve_that_can_be_called_without_arguments); + } + const error = isDecorator(node) ? + hasRestParameter ? Diagnostics.The_runtime_will_invoke_the_decorator_with_1_arguments_but_the_decorator_expects_at_least_0 : + Diagnostics.The_runtime_will_invoke_the_decorator_with_1_arguments_but_the_decorator_expects_0 : + hasRestParameter ? Diagnostics.Expected_at_least_0_arguments_but_got_1 : + isVoidPromiseError ? Diagnostics.Expected_0_arguments_but_got_1_Did_you_forget_to_include_void_in_your_type_argument_to_Promise : + Diagnostics.Expected_0_arguments_but_got_1; + + if (min < args.length && args.length < max) { + // between min and max, but with no matching overload + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_overload_expects_0_arguments_but_overloads_do_exist_that_expect_either_1_or_2_arguments, args.length, maxBelow, minAbove); + chain = chainDiagnosticMessages(chain, headMessage); + return getDiagnosticForCallNode(node, chain); + } + return getDiagnosticForCallNode(node, Diagnostics.No_overload_expects_0_arguments_but_overloads_do_exist_that_expect_either_1_or_2_arguments, args.length, maxBelow, minAbove); + } + else if (args.length < min) { + // too short: put the error span on the call expression, not any of the args + let diagnostic: Diagnostic; + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, error, parameterRange, args.length); + chain = chainDiagnosticMessages(chain, headMessage); + diagnostic = getDiagnosticForCallNode(node, chain); + } + else { + diagnostic = getDiagnosticForCallNode(node, error, parameterRange, args.length); + } + const parameter = closestSignature?.declaration?.parameters[closestSignature.thisParameter ? args.length + 1 : args.length]; + if (parameter) { + const messageAndArgs: DiagnosticAndArguments = isBindingPattern(parameter.name) ? [Diagnostics.An_argument_matching_this_binding_pattern_was_not_provided] + : isRestParameter(parameter) ? [Diagnostics.Arguments_for_the_rest_parameter_0_were_not_provided, idText(getFirstIdentifier(parameter.name))] + : [Diagnostics.An_argument_for_0_was_not_provided, !parameter.name ? args.length : idText(getFirstIdentifier(parameter.name))]; + const parameterError = createDiagnosticForNode(parameter, ...messageAndArgs); + return addRelatedInfo(diagnostic, parameterError); + } + return diagnostic; + } + else { + // too long; error goes on the excess parameters + const errorSpan = factory.createNodeArray(args.slice(max)); + const pos = first(errorSpan).pos; + let end = last(errorSpan).end; + if (end === pos) { + end++; + } + setTextRangePosEnd(errorSpan, pos, end); + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, error, parameterRange, args.length); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), errorSpan, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), errorSpan, error, parameterRange, args.length); + } + } + + function getTypeArgumentArityError(node: Node, signatures: readonly Signature[], typeArguments: NodeArray, headMessage?: DiagnosticMessage) { + const argCount = typeArguments.length; + // No overloads exist + if (signatures.length === 1) { + const sig = signatures[0]; + const min = getMinTypeArgumentCount(sig.typeParameters); + const max = length(sig.typeParameters); + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Expected_0_type_arguments_but_got_1, min < max ? min + "-" + max : min, argCount); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Expected_0_type_arguments_but_got_1, min < max ? min + "-" + max : min, argCount); + } + // Overloads exist + let belowArgCount = -Infinity; + let aboveArgCount = Infinity; + for (const sig of signatures) { + const min = getMinTypeArgumentCount(sig.typeParameters); + const max = length(sig.typeParameters); + if (min > argCount) { + aboveArgCount = Math.min(aboveArgCount, min); + } + else if (max < argCount) { + belowArgCount = Math.max(belowArgCount, max); + } + } + if (belowArgCount !== -Infinity && aboveArgCount !== Infinity) { + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_overload_expects_0_type_arguments_but_overloads_do_exist_that_expect_either_1_or_2_type_arguments, argCount, belowArgCount, aboveArgCount); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.No_overload_expects_0_type_arguments_but_overloads_do_exist_that_expect_either_1_or_2_type_arguments, argCount, belowArgCount, aboveArgCount); + } + if (headMessage) { + let chain = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Expected_0_type_arguments_but_got_1, belowArgCount === -Infinity ? aboveArgCount : belowArgCount, argCount); + chain = chainDiagnosticMessages(chain, headMessage); + return createDiagnosticForNodeArrayFromMessageChain(getSourceFileOfNode(node), typeArguments, chain); + } + return createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Expected_0_type_arguments_but_got_1, belowArgCount === -Infinity ? aboveArgCount : belowArgCount, argCount); + } + + function resolveCall(node: CallLikeExpression, signatures: readonly Signature[], candidatesOutArray: Signature[] | undefined, checkMode: CheckMode, callChainFlags: SignatureFlags, headMessage?: DiagnosticMessage): Signature { + const isTaggedTemplate = node.kind === SyntaxKind.TaggedTemplateExpression; + const isDecorator = node.kind === SyntaxKind.Decorator; + const isJsxOpeningOrSelfClosingElement = isJsxOpeningLikeElement(node); + const isInstanceof = node.kind === SyntaxKind.BinaryExpression; + const reportErrors = !isInferencePartiallyBlocked && !candidatesOutArray; + + let typeArguments: NodeArray | undefined; + + if (!isDecorator && !isInstanceof && !isSuperCall(node)) { + typeArguments = (node as CallExpression).typeArguments; + + // We already perform checking on the type arguments on the class declaration itself. + if (isTaggedTemplate || isJsxOpeningOrSelfClosingElement || (node as CallExpression).expression.kind !== SyntaxKind.SuperKeyword) { + forEach(typeArguments, checkSourceElement); + } + } + + const candidates = candidatesOutArray || []; + // reorderCandidates fills up the candidates array directly + reorderCandidates(signatures, candidates, callChainFlags); + Debug.assert(candidates.length, "Revert #54442 and add a testcase with whatever triggered this"); + + const args = getEffectiveCallArguments(node); + + // The excludeArgument array contains true for each context sensitive argument (an argument + // is context sensitive it is susceptible to a one-time permanent contextual typing). + // + // The idea is that we will perform type argument inference & assignability checking once + // without using the susceptible parameters that are functions, and once more for those + // parameters, contextually typing each as we go along. + // + // For a tagged template, then the first argument be 'undefined' if necessary because it + // represents a TemplateStringsArray. + // + // For a decorator, no arguments are susceptible to contextual typing due to the fact + // decorators are applied to a declaration by the emitter, and not to an expression. + const isSingleNonGenericCandidate = candidates.length === 1 && !candidates[0].typeParameters; + let argCheckMode = !isDecorator && !isSingleNonGenericCandidate && some(args, isContextSensitive) ? CheckMode.SkipContextSensitive : CheckMode.Normal; + + // The following variables are captured and modified by calls to chooseOverload. + // If overload resolution or type argument inference fails, we want to report the + // best error possible. The best error is one which says that an argument was not + // assignable to a parameter. This implies that everything else about the overload + // was fine. So if there is any overload that is only incorrect because of an + // argument, we will report an error on that one. + // + // function foo(s: string): void; + // function foo(n: number): void; // Report argument error on this overload + // function foo(): void; + // foo(true); + // + // If none of the overloads even made it that far, there are two possibilities. + // There was a problem with type arguments for some overload, in which case + // report an error on that. Or none of the overloads even had correct arity, + // in which case give an arity error. + // + // function foo(x: T): void; // Report type argument error + // function foo(): void; + // foo(0); + // + let candidatesForArgumentError: Signature[] | undefined; + let candidateForArgumentArityError: Signature | undefined; + let candidateForTypeArgumentError: Signature | undefined; + let result: Signature | undefined; + + // If we are in signature help, a trailing comma indicates that we intend to provide another argument, + // so we will only accept overloads with arity at least 1 higher than the current number of provided arguments. + const signatureHelpTrailingComma = !!(checkMode & CheckMode.IsForSignatureHelp) && node.kind === SyntaxKind.CallExpression && node.arguments.hasTrailingComma; + + // Section 4.12.1: + // if the candidate list contains one or more signatures for which the type of each argument + // expression is a subtype of each corresponding parameter type, the return type of the first + // of those signatures becomes the return type of the function call. + // Otherwise, the return type of the first signature in the candidate list becomes the return + // type of the function call. + // + // Whether the call is an error is determined by assignability of the arguments. The subtype pass + // is just important for choosing the best signature. So in the case where there is only one + // signature, the subtype pass is useless. So skipping it is an optimization. + if (candidates.length > 1) { + result = chooseOverload(candidates, subtypeRelation, isSingleNonGenericCandidate, signatureHelpTrailingComma); + } + if (!result) { + result = chooseOverload(candidates, assignableRelation, isSingleNonGenericCandidate, signatureHelpTrailingComma); + } + if (result) { + return result; + } + + result = getCandidateForOverloadFailure(node, candidates, args, !!candidatesOutArray, checkMode); + // Preemptively cache the result; getResolvedSignature will do this after we return, but + // we need to ensure that the result is present for the error checks below so that if + // this signature is encountered again, we handle the circularity (rather than producing a + // different result which may produce no errors and assert). Callers of getResolvedSignature + // don't hit this issue because they only observe this result after it's had a chance to + // be cached, but the error reporting code below executes before getResolvedSignature sets + // resolvedSignature. + getNodeLinks(node).resolvedSignature = result; + + // No signatures were applicable. Now report errors based on the last applicable signature with + // no arguments excluded from assignability checks. + // If candidate is undefined, it means that no candidates had a suitable arity. In that case, + // skip the checkApplicableSignature check. + if (reportErrors) { + // If the call expression is a synthetic call to a `[Symbol.hasInstance]` method then we will produce a head + // message when reporting diagnostics that explains how we got to `right[Symbol.hasInstance](left)` from + // `left instanceof right`, as it pertains to "Argument" related messages reported for the call. + if (!headMessage && isInstanceof) { + headMessage = Diagnostics.The_left_hand_side_of_an_instanceof_expression_must_be_assignable_to_the_first_argument_of_the_right_hand_side_s_Symbol_hasInstance_method; + } + if (candidatesForArgumentError) { + if (candidatesForArgumentError.length === 1 || candidatesForArgumentError.length > 3) { + const last = candidatesForArgumentError[candidatesForArgumentError.length - 1]; + let chain: DiagnosticMessageChain | undefined; + if (candidatesForArgumentError.length > 3) { + chain = chainDiagnosticMessages(chain, Diagnostics.The_last_overload_gave_the_following_error); + chain = chainDiagnosticMessages(chain, Diagnostics.No_overload_matches_this_call); + } + if (headMessage) { + chain = chainDiagnosticMessages(chain, headMessage); + } + const diags = getSignatureApplicabilityError(node, args, last, assignableRelation, CheckMode.Normal, /*reportErrors*/ true, () => chain, /*inferenceContext*/ undefined); + if (diags) { + for (const d of diags) { + if (last.declaration && candidatesForArgumentError.length > 3) { + addRelatedInfo(d, createDiagnosticForNode(last.declaration, Diagnostics.The_last_overload_is_declared_here)); + } + addImplementationSuccessElaboration(last, d); + diagnostics.add(d); + } + } + else { + Debug.fail("No error for last overload signature"); + } + } + else { + const allDiagnostics: (readonly DiagnosticRelatedInformation[])[] = []; + let max = 0; + let min = Number.MAX_VALUE; + let minIndex = 0; + let i = 0; + for (const c of candidatesForArgumentError) { + const chain = () => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Overload_0_of_1_2_gave_the_following_error, i + 1, candidates.length, signatureToString(c)); + const diags = getSignatureApplicabilityError(node, args, c, assignableRelation, CheckMode.Normal, /*reportErrors*/ true, chain, /*inferenceContext*/ undefined); + if (diags) { + if (diags.length <= min) { + min = diags.length; + minIndex = i; + } + max = Math.max(max, diags.length); + allDiagnostics.push(diags); + } + else { + Debug.fail("No error for 3 or fewer overload signatures"); + } + i++; + } + + const diags = max > 1 ? allDiagnostics[minIndex] : flatten(allDiagnostics); + Debug.assert(diags.length > 0, "No errors reported for 3 or fewer overload signatures"); + let chain = chainDiagnosticMessages( + map(diags, createDiagnosticMessageChainFromDiagnostic), + Diagnostics.No_overload_matches_this_call, + ); + if (headMessage) { + chain = chainDiagnosticMessages(chain, headMessage); + } + // The below is a spread to guarantee we get a new (mutable) array - our `flatMap` helper tries to do "smart" optimizations where it reuses input + // arrays and the emptyArray singleton where possible, which is decidedly not what we want while we're still constructing this diagnostic + const related = [...flatMap(diags, d => (d as Diagnostic).relatedInformation) as DiagnosticRelatedInformation[]]; + let diag: Diagnostic; + if (every(diags, d => d.start === diags[0].start && d.length === diags[0].length && d.file === diags[0].file)) { + const { file, start, length } = diags[0]; + diag = { file, start, length, code: chain.code, category: chain.category, messageText: chain, relatedInformation: related }; + } + else { + diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node), getErrorNodeForCallNode(node), chain, related); + } + addImplementationSuccessElaboration(candidatesForArgumentError[0], diag); + diagnostics.add(diag); + } + } + else if (candidateForArgumentArityError) { + diagnostics.add(getArgumentArityError(node, [candidateForArgumentArityError], args, headMessage)); + } + else if (candidateForTypeArgumentError) { + checkTypeArguments(candidateForTypeArgumentError, (node as CallExpression | TaggedTemplateExpression | JsxOpeningLikeElement).typeArguments!, /*reportErrors*/ true, headMessage); + } + else { + const signaturesWithCorrectTypeArgumentArity = filter(signatures, s => hasCorrectTypeArgumentArity(s, typeArguments)); + if (signaturesWithCorrectTypeArgumentArity.length === 0) { + diagnostics.add(getTypeArgumentArityError(node, signatures, typeArguments!, headMessage)); + } + else { + diagnostics.add(getArgumentArityError(node, signaturesWithCorrectTypeArgumentArity, args, headMessage)); + } + } + } + + return result; + + function addImplementationSuccessElaboration(failed: Signature, diagnostic: Diagnostic) { + const oldCandidatesForArgumentError = candidatesForArgumentError; + const oldCandidateForArgumentArityError = candidateForArgumentArityError; + const oldCandidateForTypeArgumentError = candidateForTypeArgumentError; + + const failedSignatureDeclarations = failed.declaration?.symbol?.declarations || emptyArray; + const isOverload = failedSignatureDeclarations.length > 1; + const implDecl = isOverload ? find(failedSignatureDeclarations, d => isFunctionLikeDeclaration(d) && nodeIsPresent(d.body)) : undefined; + if (implDecl) { + const candidate = getSignatureFromDeclaration(implDecl as FunctionLikeDeclaration); + const isSingleNonGenericCandidate = !candidate.typeParameters; + if (chooseOverload([candidate], assignableRelation, isSingleNonGenericCandidate)) { + addRelatedInfo(diagnostic, createDiagnosticForNode(implDecl, Diagnostics.The_call_would_have_succeeded_against_this_implementation_but_implementation_signatures_of_overloads_are_not_externally_visible)); + } + } + + candidatesForArgumentError = oldCandidatesForArgumentError; + candidateForArgumentArityError = oldCandidateForArgumentArityError; + candidateForTypeArgumentError = oldCandidateForTypeArgumentError; + } + + function chooseOverload(candidates: Signature[], relation: Map, isSingleNonGenericCandidate: boolean, signatureHelpTrailingComma = false) { + candidatesForArgumentError = undefined; + candidateForArgumentArityError = undefined; + candidateForTypeArgumentError = undefined; + + if (isSingleNonGenericCandidate) { + const candidate = candidates[0]; + if (some(typeArguments) || !hasCorrectArity(node, args, candidate, signatureHelpTrailingComma)) { + return undefined; + } + if (getSignatureApplicabilityError(node, args, candidate, relation, CheckMode.Normal, /*reportErrors*/ false, /*containingMessageChain*/ undefined, /*inferenceContext*/ undefined)) { + candidatesForArgumentError = [candidate]; + return undefined; + } + return candidate; + } + + for (let candidateIndex = 0; candidateIndex < candidates.length; candidateIndex++) { + let candidate = candidates[candidateIndex]; + if (!hasCorrectTypeArgumentArity(candidate, typeArguments) || !hasCorrectArity(node, args, candidate, signatureHelpTrailingComma)) { + continue; + } + + let checkCandidate: Signature; + let inferenceContext: InferenceContext | undefined; + + if (candidate.typeParameters) { + // If we are *inside the body of candidate*, we need to create a clone of `candidate` with differing type parameter identities, + // so our inference results for this call doesn't pollute expression types referencing the outer type parameter! + const paramLocation = candidate.typeParameters[0].symbol.declarations?.[0]?.parent; + const candidateParameterContext = paramLocation || (candidate.declaration && isConstructorDeclaration(candidate.declaration) ? candidate.declaration.parent : candidate.declaration); + if (candidateParameterContext && findAncestor(node, a => a === candidateParameterContext)) { + candidate = getImplementationSignature(candidate); + } + let typeArgumentTypes: readonly Type[] | undefined; + if (some(typeArguments)) { + typeArgumentTypes = checkTypeArguments(candidate, typeArguments, /*reportErrors*/ false); + if (!typeArgumentTypes) { + candidateForTypeArgumentError = candidate; + continue; + } + } + else { + inferenceContext = createInferenceContext(candidate.typeParameters!, candidate, /*flags*/ isInJSFile(node) ? InferenceFlags.AnyDefault : InferenceFlags.None); + // The resulting type arguments are instantiated with the inference context mapper, as the inferred types may still contain references to the inference context's + // type variables via contextual projection. These are kept generic until all inferences are locked in, so the dependencies expressed can pass constraint checks. + typeArgumentTypes = instantiateTypes(inferTypeArguments(node, candidate, args, argCheckMode | CheckMode.SkipGenericFunctions, inferenceContext), inferenceContext.nonFixingMapper); + argCheckMode |= inferenceContext.flags & InferenceFlags.SkippedGenericFunction ? CheckMode.SkipGenericFunctions : CheckMode.Normal; + } + checkCandidate = getSignatureInstantiation(candidate, typeArgumentTypes, isInJSFile(candidate.declaration), inferenceContext && inferenceContext.inferredTypeParameters); + // If the original signature has a generic rest type, instantiation may produce a + // signature with different arity and we need to perform another arity check. + if (getNonArrayRestType(candidate) && !hasCorrectArity(node, args, checkCandidate, signatureHelpTrailingComma)) { + candidateForArgumentArityError = checkCandidate; + continue; + } + } + else { + checkCandidate = candidate; + } + if (getSignatureApplicabilityError(node, args, checkCandidate, relation, argCheckMode, /*reportErrors*/ false, /*containingMessageChain*/ undefined, inferenceContext)) { + // Give preference to error candidates that have no rest parameters (as they are more specific) + (candidatesForArgumentError || (candidatesForArgumentError = [])).push(checkCandidate); + continue; + } + if (argCheckMode) { + // If one or more context sensitive arguments were excluded, we start including + // them now (and keeping do so for any subsequent candidates) and perform a second + // round of type inference and applicability checking for this particular candidate. + argCheckMode = CheckMode.Normal; + if (inferenceContext) { + const typeArgumentTypes = instantiateTypes(inferTypeArguments(node, candidate, args, argCheckMode, inferenceContext), inferenceContext.mapper); + checkCandidate = getSignatureInstantiation(candidate, typeArgumentTypes, isInJSFile(candidate.declaration), inferenceContext.inferredTypeParameters); + // If the original signature has a generic rest type, instantiation may produce a + // signature with different arity and we need to perform another arity check. + if (getNonArrayRestType(candidate) && !hasCorrectArity(node, args, checkCandidate, signatureHelpTrailingComma)) { + candidateForArgumentArityError = checkCandidate; + continue; + } + } + if (getSignatureApplicabilityError(node, args, checkCandidate, relation, argCheckMode, /*reportErrors*/ false, /*containingMessageChain*/ undefined, inferenceContext)) { + // Give preference to error candidates that have no rest parameters (as they are more specific) + (candidatesForArgumentError || (candidatesForArgumentError = [])).push(checkCandidate); + continue; + } + } + candidates[candidateIndex] = checkCandidate; + return checkCandidate; + } + + return undefined; + } + } + + // No signature was applicable. We have already reported the errors for the invalid signature. + function getCandidateForOverloadFailure( + node: CallLikeExpression, + candidates: Signature[], + args: readonly Expression[], + hasCandidatesOutArray: boolean, + checkMode: CheckMode, + ): Signature { + Debug.assert(candidates.length > 0); // Else should not have called this. + checkNodeDeferred(node); + // Normally we will combine overloads. Skip this if they have type parameters since that's hard to combine. + // Don't do this if there is a `candidatesOutArray`, + // because then we want the chosen best candidate to be one of the overloads, not a combination. + return hasCandidatesOutArray || candidates.length === 1 || candidates.some(c => !!c.typeParameters) + ? pickLongestCandidateSignature(node, candidates, args, checkMode) + : createUnionOfSignaturesForOverloadFailure(candidates); + } + + function createUnionOfSignaturesForOverloadFailure(candidates: readonly Signature[]): Signature { + const thisParameters = mapDefined(candidates, c => c.thisParameter); + let thisParameter: Symbol | undefined; + if (thisParameters.length) { + thisParameter = createCombinedSymbolFromTypes(thisParameters, thisParameters.map(getTypeOfParameter)); + } + const { min: minArgumentCount, max: maxNonRestParam } = minAndMax(candidates, getNumNonRestParameters); + const parameters: Symbol[] = []; + for (let i = 0; i < maxNonRestParam; i++) { + const symbols = mapDefined(candidates, s => + signatureHasRestParameter(s) ? + i < s.parameters.length - 1 ? s.parameters[i] : last(s.parameters) : + i < s.parameters.length ? s.parameters[i] : undefined); + Debug.assert(symbols.length !== 0); + parameters.push(createCombinedSymbolFromTypes(symbols, mapDefined(candidates, candidate => tryGetTypeAtPosition(candidate, i)))); + } + const restParameterSymbols = mapDefined(candidates, c => signatureHasRestParameter(c) ? last(c.parameters) : undefined); + let flags = SignatureFlags.IsSignatureCandidateForOverloadFailure; + if (restParameterSymbols.length !== 0) { + const type = createArrayType(getUnionType(mapDefined(candidates, tryGetRestTypeOfSignature), UnionReduction.Subtype)); + parameters.push(createCombinedSymbolForOverloadFailure(restParameterSymbols, type)); + flags |= SignatureFlags.HasRestParameter; + } + if (candidates.some(signatureHasLiteralTypes)) { + flags |= SignatureFlags.HasLiteralTypes; + } + return createSignature( + candidates[0].declaration, + /*typeParameters*/ undefined, // Before calling this we tested for `!candidates.some(c => !!c.typeParameters)`. + thisParameter, + parameters, + /*resolvedReturnType*/ getIntersectionType(candidates.map(getReturnTypeOfSignature)), + /*resolvedTypePredicate*/ undefined, + minArgumentCount, + flags, + ); + } + + function getNumNonRestParameters(signature: Signature): number { + const numParams = signature.parameters.length; + return signatureHasRestParameter(signature) ? numParams - 1 : numParams; + } + + function createCombinedSymbolFromTypes(sources: readonly Symbol[], types: Type[]): Symbol { + return createCombinedSymbolForOverloadFailure(sources, getUnionType(types, UnionReduction.Subtype)); + } + + function createCombinedSymbolForOverloadFailure(sources: readonly Symbol[], type: Type): Symbol { + // This function is currently only used for erroneous overloads, so it's good enough to just use the first source. + return createSymbolWithType(first(sources), type); + } + + function pickLongestCandidateSignature(node: CallLikeExpression, candidates: Signature[], args: readonly Expression[], checkMode: CheckMode): Signature { + // Pick the longest signature. This way we can get a contextual type for cases like: + // declare function f(a: { xa: number; xb: number; }, b: number); + // f({ | + // Also, use explicitly-supplied type arguments if they are provided, so we can get a contextual signature in cases like: + // declare function f(k: keyof T); + // f(" + const bestIndex = getLongestCandidateIndex(candidates, apparentArgumentCount === undefined ? args.length : apparentArgumentCount); + const candidate = candidates[bestIndex]; + const { typeParameters } = candidate; + if (!typeParameters) { + return candidate; + } + + const typeArgumentNodes: readonly TypeNode[] | undefined = callLikeExpressionMayHaveTypeArguments(node) ? node.typeArguments : undefined; + const instantiated = typeArgumentNodes + ? createSignatureInstantiation(candidate, getTypeArgumentsFromNodes(typeArgumentNodes, typeParameters, isInJSFile(node))) + : inferSignatureInstantiationForOverloadFailure(node, typeParameters, candidate, args, checkMode); + candidates[bestIndex] = instantiated; + return instantiated; + } + + function getTypeArgumentsFromNodes(typeArgumentNodes: readonly TypeNode[], typeParameters: readonly TypeParameter[], isJs: boolean): readonly Type[] { + const typeArguments = typeArgumentNodes.map(getTypeOfNode); + while (typeArguments.length > typeParameters.length) { + typeArguments.pop(); + } + while (typeArguments.length < typeParameters.length) { + typeArguments.push(getDefaultFromTypeParameter(typeParameters[typeArguments.length]) || getConstraintOfTypeParameter(typeParameters[typeArguments.length]) || getDefaultTypeArgumentType(isJs)); + } + return typeArguments; + } + + function inferSignatureInstantiationForOverloadFailure(node: CallLikeExpression, typeParameters: readonly TypeParameter[], candidate: Signature, args: readonly Expression[], checkMode: CheckMode): Signature { + const inferenceContext = createInferenceContext(typeParameters, candidate, /*flags*/ isInJSFile(node) ? InferenceFlags.AnyDefault : InferenceFlags.None); + const typeArgumentTypes = inferTypeArguments(node, candidate, args, checkMode | CheckMode.SkipContextSensitive | CheckMode.SkipGenericFunctions, inferenceContext); + return createSignatureInstantiation(candidate, typeArgumentTypes); + } + + function getLongestCandidateIndex(candidates: Signature[], argsCount: number): number { + let maxParamsIndex = -1; + let maxParams = -1; + + for (let i = 0; i < candidates.length; i++) { + const candidate = candidates[i]; + const paramCount = getParameterCount(candidate); + if (hasEffectiveRestParameter(candidate) || paramCount >= argsCount) { + return i; + } + if (paramCount > maxParams) { + maxParams = paramCount; + maxParamsIndex = i; + } + } + + return maxParamsIndex; + } + + function resolveCallExpression(node: CallExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + if (node.expression.kind === SyntaxKind.SuperKeyword) { + const superType = checkSuperExpression(node.expression); + if (isTypeAny(superType)) { + for (const arg of node.arguments) { + checkExpression(arg); // Still visit arguments so they get marked for visibility, etc + } + return anySignature; + } + if (!isErrorType(superType)) { + // In super call, the candidate signatures are the matching arity signatures of the base constructor function instantiated + // with the type arguments specified in the extends clause. + const baseTypeNode = getEffectiveBaseTypeNode(getContainingClass(node)!); + if (baseTypeNode) { + const baseConstructors = getInstantiatedConstructorsForTypeArguments(superType, baseTypeNode.typeArguments, baseTypeNode); + return resolveCall(node, baseConstructors, candidatesOutArray, checkMode, SignatureFlags.None); + } + } + return resolveUntypedCall(node); + } + + let callChainFlags: SignatureFlags; + let funcType = checkExpression(node.expression); + if (isCallChain(node)) { + const nonOptionalType = getOptionalExpressionType(funcType, node.expression); + callChainFlags = nonOptionalType === funcType ? SignatureFlags.None : + isOutermostOptionalChain(node) ? SignatureFlags.IsOuterCallChain : + SignatureFlags.IsInnerCallChain; + funcType = nonOptionalType; + } + else { + callChainFlags = SignatureFlags.None; + } + + funcType = checkNonNullTypeWithReporter( + funcType, + node.expression, + reportCannotInvokePossiblyNullOrUndefinedError, + ); + + if (funcType === silentNeverType) { + return silentNeverSignature; + } + + const apparentType = getApparentType(funcType); + if (isErrorType(apparentType)) { + // Another error has already been reported + return resolveErrorCall(node); + } + + // Technically, this signatures list may be incomplete. We are taking the apparent type, + // but we are not including call signatures that may have been added to the Object or + // Function interface, since they have none by default. This is a bit of a leap of faith + // that the user will not add any. + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; + + // TS 1.0 Spec: 4.12 + // In an untyped function call no TypeArgs are permitted, Args can be any argument list, no contextual + // types are provided for the argument expressions, and the result is always of type Any. + if (isUntypedFunctionCall(funcType, apparentType, callSignatures.length, numConstructSignatures)) { + // The unknownType indicates that an error already occurred (and was reported). No + // need to report another error in this case. + if (!isErrorType(funcType) && node.typeArguments) { + error(node, Diagnostics.Untyped_function_calls_may_not_accept_type_arguments); + } + return resolveUntypedCall(node); + } + // If FuncExpr's apparent type(section 3.8.1) is a function type, the call is a typed function call. + // TypeScript employs overload resolution in typed function calls in order to support functions + // with multiple call signatures. + if (!callSignatures.length) { + if (numConstructSignatures) { + error(node, Diagnostics.Value_of_type_0_is_not_callable_Did_you_mean_to_include_new, typeToString(funcType)); + } + else { + let relatedInformation: DiagnosticRelatedInformation | undefined; + if (node.arguments.length === 1) { + const text = getSourceFileOfNode(node).text; + if (isLineBreak(text.charCodeAt(skipTrivia(text, node.expression.end, /*stopAfterLineBreak*/ true) - 1))) { + relatedInformation = createDiagnosticForNode(node.expression, Diagnostics.Are_you_missing_a_semicolon); + } + } + invocationError(node.expression, apparentType, SignatureKind.Call, relatedInformation); + } + return resolveErrorCall(node); + } + // When a call to a generic function is an argument to an outer call to a generic function for which + // inference is in process, we have a choice to make. If the inner call relies on inferences made from + // its contextual type to its return type, deferring the inner call processing allows the best possible + // contextual type to accumulate. But if the outer call relies on inferences made from the return type of + // the inner call, the inner call should be processed early. There's no sure way to know which choice is + // right (only a full unification algorithm can determine that), so we resort to the following heuristic: + // If no type arguments are specified in the inner call and at least one call signature is generic and + // returns a function type, we choose to defer processing. This narrowly permits function composition + // operators to flow inferences through return types, but otherwise processes calls right away. We + // use the resolvingSignature singleton to indicate that we deferred processing. This result will be + // propagated out and eventually turned into silentNeverType (a type that is assignable to anything and + // from which we never make inferences). + if (checkMode & CheckMode.SkipGenericFunctions && !node.typeArguments && callSignatures.some(isGenericFunctionReturningFunction)) { + skippedGenericFunction(node, checkMode); + return resolvingSignature; + } + // If the function is explicitly marked with `@class`, then it must be constructed. + if (callSignatures.some(sig => isInJSFile(sig.declaration) && !!getJSDocClassTag(sig.declaration!))) { + error(node, Diagnostics.Value_of_type_0_is_not_callable_Did_you_mean_to_include_new, typeToString(funcType)); + return resolveErrorCall(node); + } + + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, callChainFlags); + } + + function isGenericFunctionReturningFunction(signature: Signature) { + return !!(signature.typeParameters && isFunctionType(getReturnTypeOfSignature(signature))); + } + + /** + * TS 1.0 spec: 4.12 + * If FuncExpr is of type Any, or of an object type that has no call or construct signatures + * but is a subtype of the Function interface, the call is an untyped function call. + */ + function isUntypedFunctionCall(funcType: Type, apparentFuncType: Type, numCallSignatures: number, numConstructSignatures: number): boolean { + // We exclude union types because we may have a union of function types that happen to have no common signatures. + return isTypeAny(funcType) || isTypeAny(apparentFuncType) && !!(funcType.flags & TypeFlags.TypeParameter) || + !numCallSignatures && !numConstructSignatures && !(apparentFuncType.flags & TypeFlags.Union) && !(getReducedType(apparentFuncType).flags & TypeFlags.Never) && isTypeAssignableTo(funcType, globalFunctionType); + } + + function resolveNewExpression(node: NewExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + let expressionType = checkNonNullExpression(node.expression); + if (expressionType === silentNeverType) { + return silentNeverSignature; + } + + // If expressionType's apparent type(section 3.8.1) is an object type with one or + // more construct signatures, the expression is processed in the same manner as a + // function call, but using the construct signatures as the initial set of candidate + // signatures for overload resolution. The result type of the function call becomes + // the result type of the operation. + expressionType = getApparentType(expressionType); + if (isErrorType(expressionType)) { + // Another error has already been reported + return resolveErrorCall(node); + } + + // TS 1.0 spec: 4.11 + // If expressionType is of type Any, Args can be any argument + // list and the result of the operation is of type Any. + if (isTypeAny(expressionType)) { + if (node.typeArguments) { + error(node, Diagnostics.Untyped_function_calls_may_not_accept_type_arguments); + } + return resolveUntypedCall(node); + } + + // Technically, this signatures list may be incomplete. We are taking the apparent type, + // but we are not including construct signatures that may have been added to the Object or + // Function interface, since they have none by default. This is a bit of a leap of faith + // that the user will not add any. + const constructSignatures = getSignaturesOfType(expressionType, SignatureKind.Construct); + if (constructSignatures.length) { + if (!isConstructorAccessible(node, constructSignatures[0])) { + return resolveErrorCall(node); + } + // If the expression is a class of abstract type, or an abstract construct signature, + // then it cannot be instantiated. + // In the case of a merged class-module or class-interface declaration, + // only the class declaration node will have the Abstract flag set. + if (someSignature(constructSignatures, signature => !!(signature.flags & SignatureFlags.Abstract))) { + error(node, Diagnostics.Cannot_create_an_instance_of_an_abstract_class); + return resolveErrorCall(node); + } + const valueDecl = expressionType.symbol && getClassLikeDeclarationOfSymbol(expressionType.symbol); + if (valueDecl && hasSyntacticModifier(valueDecl, ModifierFlags.Abstract)) { + error(node, Diagnostics.Cannot_create_an_instance_of_an_abstract_class); + return resolveErrorCall(node); + } + + return resolveCall(node, constructSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + + // If expressionType's apparent type is an object type with no construct signatures but + // one or more call signatures, the expression is processed as a function call. A compile-time + // error occurs if the result of the function call is not Void. The type of the result of the + // operation is Any. It is an error to have a Void this type. + const callSignatures = getSignaturesOfType(expressionType, SignatureKind.Call); + if (callSignatures.length) { + const signature = resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + if (!noImplicitAny) { + if (signature.declaration && !isJSConstructor(signature.declaration) && getReturnTypeOfSignature(signature) !== voidType) { + error(node, Diagnostics.Only_a_void_function_can_be_called_with_the_new_keyword); + } + if (getThisTypeOfSignature(signature) === voidType) { + error(node, Diagnostics.A_function_that_is_called_with_the_new_keyword_cannot_have_a_this_type_that_is_void); + } + } + return signature; + } + + invocationError(node.expression, expressionType, SignatureKind.Construct); + return resolveErrorCall(node); + } + + function someSignature(signatures: Signature | readonly Signature[], f: (s: Signature) => boolean): boolean { + if (isArray(signatures)) { + return some(signatures, signature => someSignature(signature, f)); + } + return signatures.compositeKind === TypeFlags.Union ? some(signatures.compositeSignatures, f) : f(signatures); + } + + function typeHasProtectedAccessibleBase(target: Symbol, type: InterfaceType): boolean { + const baseTypes = getBaseTypes(type); + if (!length(baseTypes)) { + return false; + } + const firstBase = baseTypes[0]; + if (firstBase.flags & TypeFlags.Intersection) { + const types = (firstBase as IntersectionType).types; + const mixinFlags = findMixins(types); + let i = 0; + for (const intersectionMember of (firstBase as IntersectionType).types) { + // We want to ignore mixin ctors + if (!mixinFlags[i]) { + if (getObjectFlags(intersectionMember) & (ObjectFlags.Class | ObjectFlags.Interface)) { + if (intersectionMember.symbol === target) { + return true; + } + if (typeHasProtectedAccessibleBase(target, intersectionMember as InterfaceType)) { + return true; + } + } + } + i++; + } + return false; + } + if (firstBase.symbol === target) { + return true; + } + return typeHasProtectedAccessibleBase(target, firstBase as InterfaceType); + } + + function isConstructorAccessible(node: NewExpression, signature: Signature) { + if (!signature || !signature.declaration) { + return true; + } + + const declaration = signature.declaration; + const modifiers = getSelectedEffectiveModifierFlags(declaration, ModifierFlags.NonPublicAccessibilityModifier); + + // (1) Public constructors and (2) constructor functions are always accessible. + if (!modifiers || declaration.kind !== SyntaxKind.Constructor) { + return true; + } + + const declaringClassDeclaration = getClassLikeDeclarationOfSymbol(declaration.parent.symbol)!; + const declaringClass = getDeclaredTypeOfSymbol(declaration.parent.symbol) as InterfaceType; + + // A private or protected constructor can only be instantiated within its own class (or a subclass, for protected) + if (!isNodeWithinClass(node, declaringClassDeclaration)) { + const containingClass = getContainingClass(node); + if (containingClass && modifiers & ModifierFlags.Protected) { + const containingType = getTypeOfNode(containingClass); + if (typeHasProtectedAccessibleBase(declaration.parent.symbol, containingType as InterfaceType)) { + return true; + } + } + if (modifiers & ModifierFlags.Private) { + error(node, Diagnostics.Constructor_of_class_0_is_private_and_only_accessible_within_the_class_declaration, typeToString(declaringClass)); + } + if (modifiers & ModifierFlags.Protected) { + error(node, Diagnostics.Constructor_of_class_0_is_protected_and_only_accessible_within_the_class_declaration, typeToString(declaringClass)); + } + return false; + } + + return true; + } + + function invocationErrorDetails(errorTarget: Node, apparentType: Type, kind: SignatureKind): { messageChain: DiagnosticMessageChain; relatedMessage: DiagnosticMessage | undefined; } { + let errorInfo: DiagnosticMessageChain | undefined; + const isCall = kind === SignatureKind.Call; + const awaitedType = getAwaitedType(apparentType); + const maybeMissingAwait = awaitedType && getSignaturesOfType(awaitedType, kind).length > 0; + if (apparentType.flags & TypeFlags.Union) { + const types = (apparentType as UnionType).types; + let hasSignatures = false; + for (const constituent of types) { + const signatures = getSignaturesOfType(constituent, kind); + if (signatures.length !== 0) { + hasSignatures = true; + if (errorInfo) { + // Bail early if we already have an error, no chance of "No constituent of type is callable" + break; + } + } + else { + // Error on the first non callable constituent only + if (!errorInfo) { + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Type_0_has_no_call_signatures : + Diagnostics.Type_0_has_no_construct_signatures, + typeToString(constituent), + ); + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Not_all_constituents_of_type_0_are_callable : + Diagnostics.Not_all_constituents_of_type_0_are_constructable, + typeToString(apparentType), + ); + } + if (hasSignatures) { + // Bail early if we already found a siganture, no chance of "No constituent of type is callable" + break; + } + } + } + if (!hasSignatures) { + errorInfo = chainDiagnosticMessages( + /*details*/ undefined, + isCall ? + Diagnostics.No_constituent_of_type_0_is_callable : + Diagnostics.No_constituent_of_type_0_is_constructable, + typeToString(apparentType), + ); + } + if (!errorInfo) { + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Each_member_of_the_union_type_0_has_signatures_but_none_of_those_signatures_are_compatible_with_each_other : + Diagnostics.Each_member_of_the_union_type_0_has_construct_signatures_but_none_of_those_signatures_are_compatible_with_each_other, + typeToString(apparentType), + ); + } + } + else { + errorInfo = chainDiagnosticMessages( + errorInfo, + isCall ? + Diagnostics.Type_0_has_no_call_signatures : + Diagnostics.Type_0_has_no_construct_signatures, + typeToString(apparentType), + ); + } + + let headMessage = isCall ? Diagnostics.This_expression_is_not_callable : Diagnostics.This_expression_is_not_constructable; + + // Diagnose get accessors incorrectly called as functions + if (isCallExpression(errorTarget.parent) && errorTarget.parent.arguments.length === 0) { + const { resolvedSymbol } = getNodeLinks(errorTarget); + if (resolvedSymbol && resolvedSymbol.flags & SymbolFlags.GetAccessor) { + headMessage = Diagnostics.This_expression_is_not_callable_because_it_is_a_get_accessor_Did_you_mean_to_use_it_without; + } + } + + return { + messageChain: chainDiagnosticMessages(errorInfo, headMessage), + relatedMessage: maybeMissingAwait ? Diagnostics.Did_you_forget_to_use_await : undefined, + }; + } + function invocationError(errorTarget: Node, apparentType: Type, kind: SignatureKind, relatedInformation?: DiagnosticRelatedInformation) { + const { messageChain, relatedMessage: relatedInfo } = invocationErrorDetails(errorTarget, apparentType, kind); + const diagnostic = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(errorTarget), errorTarget, messageChain); + if (relatedInfo) { + addRelatedInfo(diagnostic, createDiagnosticForNode(errorTarget, relatedInfo)); + } + if (isCallExpression(errorTarget.parent)) { + const { start, length } = getDiagnosticSpanForCallNode(errorTarget.parent); + diagnostic.start = start; + diagnostic.length = length; + } + diagnostics.add(diagnostic); + invocationErrorRecovery(apparentType, kind, relatedInformation ? addRelatedInfo(diagnostic, relatedInformation) : diagnostic); + } + + function invocationErrorRecovery(apparentType: Type, kind: SignatureKind, diagnostic: Diagnostic) { + if (!apparentType.symbol) { + return; + } + const importNode = getSymbolLinks(apparentType.symbol).originatingImport; + // Create a diagnostic on the originating import if possible onto which we can attach a quickfix + // An import call expression cannot be rewritten into another form to correct the error - the only solution is to use `.default` at the use-site + if (importNode && !isImportCall(importNode)) { + const sigs = getSignaturesOfType(getTypeOfSymbol(getSymbolLinks(apparentType.symbol).target!), kind); + if (!sigs || !sigs.length) return; + + addRelatedInfo(diagnostic, createDiagnosticForNode(importNode, Diagnostics.Type_originates_at_this_import_A_namespace_style_import_cannot_be_called_or_constructed_and_will_cause_a_failure_at_runtime_Consider_using_a_default_import_or_import_require_here_instead)); + } + } + + function resolveTaggedTemplateExpression(node: TaggedTemplateExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + const tagType = checkExpression(node.tag); + const apparentType = getApparentType(tagType); + + if (isErrorType(apparentType)) { + // Another error has already been reported + return resolveErrorCall(node); + } + + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; + + if (isUntypedFunctionCall(tagType, apparentType, callSignatures.length, numConstructSignatures)) { + return resolveUntypedCall(node); + } + + if (!callSignatures.length) { + if (isArrayLiteralExpression(node.parent)) { + const diagnostic = createDiagnosticForNode(node.tag, Diagnostics.It_is_likely_that_you_are_missing_a_comma_to_separate_these_two_template_expressions_They_form_a_tagged_template_expression_which_cannot_be_invoked); + diagnostics.add(diagnostic); + return resolveErrorCall(node); + } + + invocationError(node.tag, apparentType, SignatureKind.Call); + return resolveErrorCall(node); + } + + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + + /** + * Gets the localized diagnostic head message to use for errors when resolving a decorator as a call expression. + */ + function getDiagnosticHeadMessageForDecoratorResolution(node: Decorator) { + switch (node.parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: + return Diagnostics.Unable_to_resolve_signature_of_class_decorator_when_called_as_an_expression; + + case SyntaxKind.Parameter: + return Diagnostics.Unable_to_resolve_signature_of_parameter_decorator_when_called_as_an_expression; + + case SyntaxKind.PropertyDeclaration: + return Diagnostics.Unable_to_resolve_signature_of_property_decorator_when_called_as_an_expression; + + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return Diagnostics.Unable_to_resolve_signature_of_method_decorator_when_called_as_an_expression; + + default: + return Debug.fail(); + } + } + + /** + * Resolves a decorator as if it were a call expression. + */ + function resolveDecorator(node: Decorator, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + const funcType = checkExpression(node.expression); + const apparentType = getApparentType(funcType); + if (isErrorType(apparentType)) { + return resolveErrorCall(node); + } + + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const numConstructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct).length; + if (isUntypedFunctionCall(funcType, apparentType, callSignatures.length, numConstructSignatures)) { + return resolveUntypedCall(node); + } + + if (isPotentiallyUncalledDecorator(node, callSignatures) && !isParenthesizedExpression(node.expression)) { + const nodeStr = getTextOfNode(node.expression, /*includeTrivia*/ false); + error(node, Diagnostics._0_accepts_too_few_arguments_to_be_used_as_a_decorator_here_Did_you_mean_to_call_it_first_and_write_0, nodeStr); + return resolveErrorCall(node); + } + + const headMessage = getDiagnosticHeadMessageForDecoratorResolution(node); + if (!callSignatures.length) { + const errorDetails = invocationErrorDetails(node.expression, apparentType, SignatureKind.Call); + const messageChain = chainDiagnosticMessages(errorDetails.messageChain, headMessage); + const diag = createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(node.expression), node.expression, messageChain); + if (errorDetails.relatedMessage) { + addRelatedInfo(diag, createDiagnosticForNode(node.expression, errorDetails.relatedMessage)); + } + diagnostics.add(diag); + invocationErrorRecovery(apparentType, SignatureKind.Call, diag); + return resolveErrorCall(node); + } + + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None, headMessage); + } + + function createSignatureForJSXIntrinsic(node: JsxOpeningLikeElement, result: Type): Signature { + const namespace = getJsxNamespaceAt(node); + const exports = namespace && getExportsOfSymbol(namespace); + // We fake up a SFC signature for each intrinsic, however a more specific per-element signature drawn from the JSX declaration + // file would probably be preferable. + const typeSymbol = exports && getSymbol(exports, JsxNames.Element, SymbolFlags.Type); + const returnNode = typeSymbol && nodeBuilder.symbolToEntityName(typeSymbol, SymbolFlags.Type, node); + const declaration = factory.createFunctionTypeNode(/*typeParameters*/ undefined, [factory.createParameterDeclaration(/*modifiers*/ undefined, /*dotDotDotToken*/ undefined, "props", /*questionToken*/ undefined, nodeBuilder.typeToTypeNode(result, node))], returnNode ? factory.createTypeReferenceNode(returnNode, /*typeArguments*/ undefined) : factory.createKeywordTypeNode(SyntaxKind.AnyKeyword)); + const parameterSymbol = createSymbol(SymbolFlags.FunctionScopedVariable, "props" as __String); + parameterSymbol.links.type = result; + return createSignature( + declaration, + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [parameterSymbol], + typeSymbol ? getDeclaredTypeOfSymbol(typeSymbol) : errorType, + /*resolvedTypePredicate*/ undefined, + 1, + SignatureFlags.None, + ); + } + + function resolveJsxOpeningLikeElement(node: JsxOpeningLikeElement, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + if (isJsxIntrinsicTagName(node.tagName)) { + const result = getIntrinsicAttributesTypeFromJsxOpeningLikeElement(node); + const fakeSignature = createSignatureForJSXIntrinsic(node, result); + checkTypeAssignableToAndOptionallyElaborate(checkExpressionWithContextualType(node.attributes, getEffectiveFirstArgumentForJsxSignature(fakeSignature, node), /*inferenceContext*/ undefined, CheckMode.Normal), result, node.tagName, node.attributes); + if (length(node.typeArguments)) { + forEach(node.typeArguments, checkSourceElement); + diagnostics.add(createDiagnosticForNodeArray(getSourceFileOfNode(node), node.typeArguments!, Diagnostics.Expected_0_type_arguments_but_got_1, 0, length(node.typeArguments))); + } + return fakeSignature; + } + const exprTypes = checkExpression(node.tagName); + const apparentType = getApparentType(exprTypes); + if (isErrorType(apparentType)) { + return resolveErrorCall(node); + } + + const signatures = getUninstantiatedJsxSignaturesOfType(exprTypes, node); + if (isUntypedFunctionCall(exprTypes, apparentType, signatures.length, /*constructSignatures*/ 0)) { + return resolveUntypedCall(node); + } + + if (signatures.length === 0) { + // We found no signatures at all, which is an error + error(node.tagName, Diagnostics.JSX_element_type_0_does_not_have_any_construct_or_call_signatures, getTextOfNode(node.tagName)); + return resolveErrorCall(node); + } + + return resolveCall(node, signatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + + function resolveInstanceofExpression(node: InstanceofExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + // if rightType is an object type with a custom `[Symbol.hasInstance]` method, then it is potentially + // valid on the right-hand side of the `instanceof` operator. This allows normal `object` types to + // participate in `instanceof`, as per Step 2 of https://tc39.es/ecma262/#sec-instanceofoperator. + const rightType = checkExpression(node.right); + if (!isTypeAny(rightType)) { + const hasInstanceMethodType = getSymbolHasInstanceMethodOfObjectType(rightType); + if (hasInstanceMethodType) { + const apparentType = getApparentType(hasInstanceMethodType); + if (isErrorType(apparentType)) { + return resolveErrorCall(node); + } + + const callSignatures = getSignaturesOfType(apparentType, SignatureKind.Call); + const constructSignatures = getSignaturesOfType(apparentType, SignatureKind.Construct); + if (isUntypedFunctionCall(hasInstanceMethodType, apparentType, callSignatures.length, constructSignatures.length)) { + return resolveUntypedCall(node); + } + + if (callSignatures.length) { + return resolveCall(node, callSignatures, candidatesOutArray, checkMode, SignatureFlags.None); + } + } + // NOTE: do not raise error if right is unknown as related error was already reported + else if (!(typeHasCallOrConstructSignatures(rightType) || isTypeSubtypeOf(rightType, globalFunctionType))) { + error(node.right, Diagnostics.The_right_hand_side_of_an_instanceof_expression_must_be_either_of_type_any_a_class_function_or_other_type_assignable_to_the_Function_interface_type_or_an_object_type_with_a_Symbol_hasInstance_method); + return resolveErrorCall(node); + } + } + // fall back to a default signature + return anySignature; + } + + /** + * Sometimes, we have a decorator that could accept zero arguments, + * but is receiving too many arguments as part of the decorator invocation. + * In those cases, a user may have meant to *call* the expression before using it as a decorator. + */ + function isPotentiallyUncalledDecorator(decorator: Decorator, signatures: readonly Signature[]) { + return signatures.length && every(signatures, signature => + signature.minArgumentCount === 0 && + !signatureHasRestParameter(signature) && + signature.parameters.length < getDecoratorArgumentCount(decorator, signature)); + } + + function resolveSignature(node: CallLikeExpression, candidatesOutArray: Signature[] | undefined, checkMode: CheckMode): Signature { + switch (node.kind) { + case SyntaxKind.CallExpression: + return resolveCallExpression(node, candidatesOutArray, checkMode); + case SyntaxKind.NewExpression: + return resolveNewExpression(node, candidatesOutArray, checkMode); + case SyntaxKind.TaggedTemplateExpression: + return resolveTaggedTemplateExpression(node, candidatesOutArray, checkMode); + case SyntaxKind.Decorator: + return resolveDecorator(node, candidatesOutArray, checkMode); + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.JsxSelfClosingElement: + return resolveJsxOpeningLikeElement(node, candidatesOutArray, checkMode); + case SyntaxKind.BinaryExpression: + return resolveInstanceofExpression(node, candidatesOutArray, checkMode); + } + Debug.assertNever(node, "Branch in 'resolveSignature' should be unreachable."); + } + + /** + * Resolve a signature of a given call-like expression. + * @param node a call-like expression to try resolve a signature for + * @param candidatesOutArray an array of signature to be filled in by the function. It is passed by signature help in the language service; + * the function will fill it up with appropriate candidate signatures + * @return a signature of the call-like expression or undefined if one can't be found + */ + function getResolvedSignature(node: CallLikeExpression, candidatesOutArray?: Signature[] | undefined, checkMode?: CheckMode): Signature { + const links = getNodeLinks(node); + // If getResolvedSignature has already been called, we will have cached the resolvedSignature. + // However, it is possible that either candidatesOutArray was not passed in the first time, + // or that a different candidatesOutArray was passed in. Therefore, we need to redo the work + // to correctly fill the candidatesOutArray. + const cached = links.resolvedSignature; + if (cached && cached !== resolvingSignature && !candidatesOutArray) { + return cached; + } + const saveResolutionStart = resolutionStart; + if (!cached) { + // If we haven't already done so, temporarily reset the resolution stack. This allows us to + // handle "inverted" situations where, for example, an API client asks for the type of a symbol + // containined in a function call argument whose contextual type depends on the symbol itself + // through resolution of the containing function call. By resetting the resolution stack we'll + // retry the symbol type resolution with the resolvingSignature marker in place to suppress + // the contextual type circularity. + resolutionStart = resolutionTargets.length; + } + links.resolvedSignature = resolvingSignature; + let result = resolveSignature(node, candidatesOutArray, checkMode || CheckMode.Normal); + resolutionStart = saveResolutionStart; + // When CheckMode.SkipGenericFunctions is set we use resolvingSignature to indicate that call + // resolution should be deferred. + if (result !== resolvingSignature) { + // if the signature resolution originated on a node that itself depends on the contextual type + // then it's possible that the resolved signature might not be the same as the one that would be computed in source order + // since resolving such signature leads to resolving the potential outer signature, its arguments and thus the very same signature + // it's possible that this inner resolution sets the resolvedSignature first. + // In such a case we ignore the local result and reuse the correct one that was cached. + if (links.resolvedSignature !== resolvingSignature) { + result = links.resolvedSignature; + } + // If signature resolution originated in control flow type analysis (for example to compute the + // assigned type in a flow assignment) we don't cache the result as it may be based on temporary + // types from the control flow analysis. + links.resolvedSignature = flowLoopStart === flowLoopCount ? result : cached; + } + return result; + } + + /** + * Indicates whether a declaration can be treated as a constructor in a JavaScript + * file. + */ + function isJSConstructor(node: Node | undefined): node is FunctionDeclaration | FunctionExpression { + if (!node || !isInJSFile(node)) { + return false; + } + const func = isFunctionDeclaration(node) || isFunctionExpression(node) ? node : + (isVariableDeclaration(node) || isPropertyAssignment(node)) && node.initializer && isFunctionExpression(node.initializer) ? node.initializer : + undefined; + if (func) { + // If the node has a @class or @constructor tag, treat it like a constructor. + if (getJSDocClassTag(node)) return true; + + // If the node is a property of an object literal. + if (isPropertyAssignment(walkUpParenthesizedExpressions(func.parent))) return false; + + // If the symbol of the node has members, treat it like a constructor. + const symbol = getSymbolOfDeclaration(func); + return !!symbol?.members?.size; + } + return false; + } + + function mergeJSSymbols(target: Symbol, source: Symbol | undefined) { + if (source) { + const links = getSymbolLinks(source); + if (!links.inferredClassSymbol || !links.inferredClassSymbol.has(getSymbolId(target))) { + const inferred = isTransientSymbol(target) ? target : cloneSymbol(target); + inferred.exports = inferred.exports || createSymbolTable(); + inferred.members = inferred.members || createSymbolTable(); + inferred.flags |= source.flags & SymbolFlags.Class; + if (source.exports?.size) { + mergeSymbolTable(inferred.exports, source.exports); + } + if (source.members?.size) { + mergeSymbolTable(inferred.members, source.members); + } + (links.inferredClassSymbol || (links.inferredClassSymbol = new Map())).set(getSymbolId(inferred), inferred); + return inferred; + } + return links.inferredClassSymbol.get(getSymbolId(target)); + } + } + + function getAssignedClassSymbol(decl: Declaration): Symbol | undefined { + const assignmentSymbol = decl && getSymbolOfExpando(decl, /*allowDeclaration*/ true); + const prototype = assignmentSymbol?.exports?.get("prototype" as __String); + const init = prototype?.valueDeclaration && getAssignedJSPrototype(prototype.valueDeclaration); + return init ? getSymbolOfDeclaration(init) : undefined; + } + + function getSymbolOfExpando(node: Node, allowDeclaration: boolean): Symbol | undefined { + if (!node.parent) { + return undefined; + } + let name: Expression | BindingName | undefined; + let decl: Node | undefined; + if (isVariableDeclaration(node.parent) && node.parent.initializer === node) { + if (!isInJSFile(node) && !(isVarConstLike(node.parent) && isFunctionLikeDeclaration(node))) { + return undefined; + } + name = node.parent.name; + decl = node.parent; + } + else if (isBinaryExpression(node.parent)) { + const parentNode = node.parent; + const parentNodeOperator = node.parent.operatorToken.kind; + if (parentNodeOperator === SyntaxKind.EqualsToken && (allowDeclaration || parentNode.right === node)) { + name = parentNode.left; + decl = name; + } + else if (parentNodeOperator === SyntaxKind.BarBarToken || parentNodeOperator === SyntaxKind.QuestionQuestionToken) { + if (isVariableDeclaration(parentNode.parent) && parentNode.parent.initializer === parentNode) { + name = parentNode.parent.name; + decl = parentNode.parent; + } + else if (isBinaryExpression(parentNode.parent) && parentNode.parent.operatorToken.kind === SyntaxKind.EqualsToken && (allowDeclaration || parentNode.parent.right === parentNode)) { + name = parentNode.parent.left; + decl = name; + } + + if (!name || !isBindableStaticNameExpression(name) || !isSameEntityName(name, parentNode.left)) { + return undefined; + } + } + } + else if (allowDeclaration && isFunctionDeclaration(node)) { + name = node.name; + decl = node; + } + + if (!decl || !name || (!allowDeclaration && !getExpandoInitializer(node, isPrototypeAccess(name)))) { + return undefined; + } + return getSymbolOfNode(decl); + } + + function getAssignedJSPrototype(node: Node) { + if (!node.parent) { + return false; + } + let parent: Node = node.parent; + while (parent && parent.kind === SyntaxKind.PropertyAccessExpression) { + parent = parent.parent; + } + if (parent && isBinaryExpression(parent) && isPrototypeAccess(parent.left) && parent.operatorToken.kind === SyntaxKind.EqualsToken) { + const right = getInitializerOfBinaryExpression(parent); + return isObjectLiteralExpression(right) && right; + } + } + + /** + * Syntactically and semantically checks a call or new expression. + * @param node The call/new expression to be checked. + * @returns On success, the expression's signature's return type. On failure, anyType. + */ + function checkCallExpression(node: CallExpression | NewExpression, checkMode?: CheckMode): Type { + checkGrammarTypeArguments(node, node.typeArguments); + + const signature = getResolvedSignature(node, /*candidatesOutArray*/ undefined, checkMode); + if (signature === resolvingSignature) { + // CheckMode.SkipGenericFunctions is enabled and this is a call to a generic function that + // returns a function type. We defer checking and return silentNeverType. + return silentNeverType; + } + + checkDeprecatedSignature(signature, node); + + if (node.expression.kind === SyntaxKind.SuperKeyword) { + return voidType; + } + + if (node.kind === SyntaxKind.NewExpression) { + const declaration = signature.declaration; + + if ( + declaration && + declaration.kind !== SyntaxKind.Constructor && + declaration.kind !== SyntaxKind.ConstructSignature && + declaration.kind !== SyntaxKind.ConstructorType && + !(isJSDocSignature(declaration) && getJSDocRoot(declaration)?.parent?.kind === SyntaxKind.Constructor) && + !isJSDocConstructSignature(declaration) && + !isJSConstructor(declaration) + ) { + // When resolved signature is a call signature (and not a construct signature) the result type is any + if (noImplicitAny) { + error(node, Diagnostics.new_expression_whose_target_lacks_a_construct_signature_implicitly_has_an_any_type); + } + return anyType; + } + } + + // In JavaScript files, calls to any identifier 'require' are treated as external module imports + if (isInJSFile(node) && isCommonJsRequire(node)) { + return resolveExternalModuleTypeByLiteral(node.arguments![0] as StringLiteral); + } + + const returnType = getReturnTypeOfSignature(signature); + // Treat any call to the global 'Symbol' function that is part of a const variable or readonly property + // as a fresh unique symbol literal type. + if (returnType.flags & TypeFlags.ESSymbolLike && isSymbolOrSymbolForCall(node)) { + return getESSymbolLikeTypeForNode(walkUpParenthesizedExpressions(node.parent)); + } + if ( + node.kind === SyntaxKind.CallExpression && !node.questionDotToken && node.parent.kind === SyntaxKind.ExpressionStatement && + returnType.flags & TypeFlags.Void && getTypePredicateOfSignature(signature) + ) { + if (!isDottedName(node.expression)) { + error(node.expression, Diagnostics.Assertions_require_the_call_target_to_be_an_identifier_or_qualified_name); + } + else if (!getEffectsSignature(node)) { + const diagnostic = error(node.expression, Diagnostics.Assertions_require_every_name_in_the_call_target_to_be_declared_with_an_explicit_type_annotation); + getTypeOfDottedName(node.expression, diagnostic); + } + } + + if (isInJSFile(node)) { + const jsSymbol = getSymbolOfExpando(node, /*allowDeclaration*/ false); + if (jsSymbol?.exports?.size) { + const jsAssignmentType = createAnonymousType(jsSymbol, jsSymbol.exports, emptyArray, emptyArray, emptyArray); + jsAssignmentType.objectFlags |= ObjectFlags.JSLiteral; + return getIntersectionType([returnType, jsAssignmentType]); + } + } + + return returnType; + } + + function checkDeprecatedSignature(signature: Signature, node: CallLikeExpression) { + if (signature.flags & SignatureFlags.IsSignatureCandidateForOverloadFailure) return; + if (signature.declaration && signature.declaration.flags & NodeFlags.Deprecated) { + const suggestionNode = getDeprecatedSuggestionNode(node); + const name = tryGetPropertyAccessOrIdentifierToString(getInvokedExpression(node)); + addDeprecatedSuggestionWithSignature(suggestionNode, signature.declaration, name, signatureToString(signature)); + } + } + + function getDeprecatedSuggestionNode(node: Node): Node { + node = skipParentheses(node); + switch (node.kind) { + case SyntaxKind.CallExpression: + case SyntaxKind.Decorator: + case SyntaxKind.NewExpression: + return getDeprecatedSuggestionNode((node as Decorator | CallExpression | NewExpression).expression); + case SyntaxKind.TaggedTemplateExpression: + return getDeprecatedSuggestionNode((node as TaggedTemplateExpression).tag); + case SyntaxKind.JsxOpeningElement: + case SyntaxKind.JsxSelfClosingElement: + return getDeprecatedSuggestionNode((node as JsxOpeningLikeElement).tagName); + case SyntaxKind.ElementAccessExpression: + return (node as ElementAccessExpression).argumentExpression; + case SyntaxKind.PropertyAccessExpression: + return (node as PropertyAccessExpression).name; + case SyntaxKind.TypeReference: + const typeReference = node as TypeReferenceNode; + return isQualifiedName(typeReference.typeName) ? typeReference.typeName.right : typeReference; + default: + return node; + } + } + + function isSymbolOrSymbolForCall(node: Node) { + if (!isCallExpression(node)) return false; + let left = node.expression; + if (isPropertyAccessExpression(left) && left.name.escapedText === "for") { + left = left.expression; + } + if (!isIdentifier(left) || left.escapedText !== "Symbol") { + return false; + } + + // make sure `Symbol` is the global symbol + const globalESSymbol = getGlobalESSymbolConstructorSymbol(/*reportErrors*/ false); + if (!globalESSymbol) { + return false; + } + + return globalESSymbol === resolveName(left, "Symbol" as __String, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + } + + function checkImportCallExpression(node: ImportCall): Type { + // Check grammar of dynamic import + checkGrammarImportCallExpression(node); + + if (node.arguments.length === 0) { + return createPromiseReturnType(node, anyType); + } + + const specifier = node.arguments[0]; + const specifierType = checkExpressionCached(specifier); + const optionsType = node.arguments.length > 1 ? checkExpressionCached(node.arguments[1]) : undefined; + // Even though multiple arguments is grammatically incorrect, type-check extra arguments for completion + for (let i = 2; i < node.arguments.length; ++i) { + checkExpressionCached(node.arguments[i]); + } + + if (specifierType.flags & TypeFlags.Undefined || specifierType.flags & TypeFlags.Null || !isTypeAssignableTo(specifierType, stringType)) { + error(specifier, Diagnostics.Dynamic_import_s_specifier_must_be_of_type_string_but_here_has_type_0, typeToString(specifierType)); + } + + if (optionsType) { + const importCallOptionsType = getGlobalImportCallOptionsType(/*reportErrors*/ true); + if (importCallOptionsType !== emptyObjectType) { + checkTypeAssignableTo(optionsType, getNullableType(importCallOptionsType, TypeFlags.Undefined), node.arguments[1]); + } + } + + // resolveExternalModuleName will return undefined if the moduleReferenceExpression is not a string literal + const moduleSymbol = resolveExternalModuleName(node, specifier); + if (moduleSymbol) { + const esModuleSymbol = resolveESModuleSymbol(moduleSymbol, specifier, /*dontResolveAlias*/ true, /*suppressInteropError*/ false); + if (esModuleSymbol) { + return createPromiseReturnType( + node, + getTypeWithSyntheticDefaultOnly(getTypeOfSymbol(esModuleSymbol), esModuleSymbol, moduleSymbol, specifier) || + getTypeWithSyntheticDefaultImportType(getTypeOfSymbol(esModuleSymbol), esModuleSymbol, moduleSymbol, specifier), + ); + } + } + return createPromiseReturnType(node, anyType); + } + + function createDefaultPropertyWrapperForModule(symbol: Symbol, originalSymbol: Symbol | undefined, anonymousSymbol?: Symbol | undefined) { + const memberTable = createSymbolTable(); + const newSymbol = createSymbol(SymbolFlags.Alias, InternalSymbolName.Default); + newSymbol.parent = originalSymbol; + newSymbol.links.nameType = getStringLiteralType("default"); + newSymbol.links.aliasTarget = resolveSymbol(symbol); + memberTable.set(InternalSymbolName.Default, newSymbol); + return createAnonymousType(anonymousSymbol, memberTable, emptyArray, emptyArray, emptyArray); + } + + function getTypeWithSyntheticDefaultOnly(type: Type, symbol: Symbol, originalSymbol: Symbol, moduleSpecifier: Expression) { + const hasDefaultOnly = isOnlyImportedAsDefault(moduleSpecifier); + if (hasDefaultOnly && type && !isErrorType(type)) { + const synthType = type as SyntheticDefaultModuleType; + if (!synthType.defaultOnlyType) { + const type = createDefaultPropertyWrapperForModule(symbol, originalSymbol); + synthType.defaultOnlyType = type; + } + return synthType.defaultOnlyType; + } + return undefined; + } + + function getTypeWithSyntheticDefaultImportType(type: Type, symbol: Symbol, originalSymbol: Symbol, moduleSpecifier: Expression): Type { + if (allowSyntheticDefaultImports && type && !isErrorType(type)) { + const synthType = type as SyntheticDefaultModuleType; + if (!synthType.syntheticType) { + const file = originalSymbol.declarations?.find(isSourceFile); + const hasSyntheticDefault = canHaveSyntheticDefault(file, originalSymbol, /*dontResolveAlias*/ false, moduleSpecifier); + if (hasSyntheticDefault) { + const anonymousSymbol = createSymbol(SymbolFlags.TypeLiteral, InternalSymbolName.Type); + const defaultContainingObject = createDefaultPropertyWrapperForModule(symbol, originalSymbol, anonymousSymbol); + anonymousSymbol.links.type = defaultContainingObject; + synthType.syntheticType = isValidSpreadType(type) ? getSpreadType(type, defaultContainingObject, anonymousSymbol, /*objectFlags*/ 0, /*readonly*/ false) : defaultContainingObject; + } + else { + synthType.syntheticType = type; + } + } + return synthType.syntheticType; + } + return type; + } + + function isCommonJsRequire(node: Node): boolean { + if (!isRequireCall(node, /*requireStringLiteralLikeArgument*/ true)) { + return false; + } + + // Make sure require is not a local function + if (!isIdentifier(node.expression)) return Debug.fail(); + const resolvedRequire = resolveName(node.expression, node.expression.escapedText, SymbolFlags.Value, /*nameNotFoundMessage*/ undefined, /*isUse*/ true)!; // TODO: GH#18217 + if (resolvedRequire === requireSymbol) { + return true; + } + // project includes symbol named 'require' - make sure that it is ambient and local non-alias + if (resolvedRequire.flags & SymbolFlags.Alias) { + return false; + } + + const targetDeclarationKind = resolvedRequire.flags & SymbolFlags.Function + ? SyntaxKind.FunctionDeclaration + : resolvedRequire.flags & SymbolFlags.Variable + ? SyntaxKind.VariableDeclaration + : SyntaxKind.Unknown; + if (targetDeclarationKind !== SyntaxKind.Unknown) { + const decl = getDeclarationOfKind(resolvedRequire, targetDeclarationKind)!; + // function/variable declaration should be ambient + return !!decl && !!(decl.flags & NodeFlags.Ambient); + } + return false; + } + + function checkTaggedTemplateExpression(node: TaggedTemplateExpression): Type { + if (!checkGrammarTaggedTemplateChain(node)) checkGrammarTypeArguments(node, node.typeArguments); + if (languageVersion < LanguageFeatureMinimumTarget.TaggedTemplates) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.MakeTemplateObject); + } + const signature = getResolvedSignature(node); + checkDeprecatedSignature(signature, node); + return getReturnTypeOfSignature(signature); + } + + function checkAssertion(node: AssertionExpression, checkMode: CheckMode | undefined) { + if (node.kind === SyntaxKind.TypeAssertionExpression) { + const file = getSourceFileOfNode(node); + if (file && fileExtensionIsOneOf(file.fileName, [Extension.Cts, Extension.Mts])) { + grammarErrorOnNode(node, Diagnostics.This_syntax_is_reserved_in_files_with_the_mts_or_cts_extension_Use_an_as_expression_instead); + } + } + return checkAssertionWorker(node, checkMode); + } + + function isValidConstAssertionArgument(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.StringLiteral: + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.NumericLiteral: + case SyntaxKind.BigIntLiteral: + case SyntaxKind.TrueKeyword: + case SyntaxKind.FalseKeyword: + case SyntaxKind.ArrayLiteralExpression: + case SyntaxKind.ObjectLiteralExpression: + case SyntaxKind.TemplateExpression: + return true; + case SyntaxKind.ParenthesizedExpression: + return isValidConstAssertionArgument((node as ParenthesizedExpression).expression); + case SyntaxKind.PrefixUnaryExpression: + const op = (node as PrefixUnaryExpression).operator; + const arg = (node as PrefixUnaryExpression).operand; + return op === SyntaxKind.MinusToken && (arg.kind === SyntaxKind.NumericLiteral || arg.kind === SyntaxKind.BigIntLiteral) || + op === SyntaxKind.PlusToken && arg.kind === SyntaxKind.NumericLiteral; + case SyntaxKind.PropertyAccessExpression: + case SyntaxKind.ElementAccessExpression: + const expr = skipParentheses((node as PropertyAccessExpression | ElementAccessExpression).expression); + const symbol = isEntityNameExpression(expr) ? resolveEntityName(expr, SymbolFlags.Value, /*ignoreErrors*/ true) : undefined; + return !!(symbol && symbol.flags & SymbolFlags.Enum); + } + return false; + } + + function checkAssertionWorker(node: JSDocTypeAssertion | AssertionExpression, checkMode: CheckMode | undefined) { + const { type, expression } = getAssertionTypeAndExpression(node); + const exprType = checkExpression(expression, checkMode); + if (isConstTypeReference(type)) { + if (!isValidConstAssertionArgument(expression)) { + error(expression, Diagnostics.A_const_assertions_can_only_be_applied_to_references_to_enum_members_or_string_number_boolean_array_or_object_literals); + } + return getRegularTypeOfLiteralType(exprType); + } + const links = getNodeLinks(node); + links.assertionExpressionType = exprType; + checkSourceElement(type); + checkNodeDeferred(node); + return getTypeFromTypeNode(type); + } + + function getAssertionTypeAndExpression(node: JSDocTypeAssertion | AssertionExpression) { + let type: TypeNode; + let expression: Expression; + switch (node.kind) { + case SyntaxKind.AsExpression: + case SyntaxKind.TypeAssertionExpression: + type = node.type; + expression = node.expression; + break; + case SyntaxKind.ParenthesizedExpression: + type = getJSDocTypeAssertionType(node); + expression = node.expression; + break; + } + + return { type, expression }; + } + + function checkAssertionDeferred(node: JSDocTypeAssertion | AssertionExpression) { + const { type } = getAssertionTypeAndExpression(node); + const errNode = isParenthesizedExpression(node) ? type : node; + const links = getNodeLinks(node); + Debug.assertIsDefined(links.assertionExpressionType); + const exprType = getRegularTypeOfObjectLiteral(getBaseTypeOfLiteralType(links.assertionExpressionType)); + const targetType = getTypeFromTypeNode(type); + if (!isErrorType(targetType)) { + addLazyDiagnostic(() => { + const widenedType = getWidenedType(exprType); + if (!isTypeComparableTo(targetType, widenedType)) { + checkTypeComparableTo(exprType, targetType, errNode, Diagnostics.Conversion_of_type_0_to_type_1_may_be_a_mistake_because_neither_type_sufficiently_overlaps_with_the_other_If_this_was_intentional_convert_the_expression_to_unknown_first); + } + }); + } + } + + function checkNonNullChain(node: NonNullChain) { + const leftType = checkExpression(node.expression); + const nonOptionalType = getOptionalExpressionType(leftType, node.expression); + return propagateOptionalTypeMarker(getNonNullableType(nonOptionalType), node, nonOptionalType !== leftType); + } + + function checkNonNullAssertion(node: NonNullExpression) { + return node.flags & NodeFlags.OptionalChain ? checkNonNullChain(node as NonNullChain) : + getNonNullableType(checkExpression(node.expression)); + } + + function checkExpressionWithTypeArguments(node: ExpressionWithTypeArguments | TypeQueryNode) { + checkGrammarExpressionWithTypeArguments(node); + forEach(node.typeArguments, checkSourceElement); + if (node.kind === SyntaxKind.ExpressionWithTypeArguments) { + const parent = walkUpParenthesizedExpressions(node.parent); + if (parent.kind === SyntaxKind.BinaryExpression && (parent as BinaryExpression).operatorToken.kind === SyntaxKind.InstanceOfKeyword && isNodeDescendantOf(node, (parent as BinaryExpression).right)) { + error(node, Diagnostics.The_right_hand_side_of_an_instanceof_expression_must_not_be_an_instantiation_expression); + } + } + const exprType = node.kind === SyntaxKind.ExpressionWithTypeArguments ? checkExpression(node.expression) : + isThisIdentifier(node.exprName) ? checkThisExpression(node.exprName) : + checkExpression(node.exprName); + return getInstantiationExpressionType(exprType, node); + } + + function getInstantiationExpressionType(exprType: Type, node: NodeWithTypeArguments) { + const typeArguments = node.typeArguments; + if (exprType === silentNeverType || isErrorType(exprType) || !some(typeArguments)) { + return exprType; + } + let hasSomeApplicableSignature = false; + let nonApplicableType: Type | undefined; + const result = getInstantiatedType(exprType); + const errorType = hasSomeApplicableSignature ? nonApplicableType : exprType; + if (errorType) { + diagnostics.add(createDiagnosticForNodeArray(getSourceFileOfNode(node), typeArguments, Diagnostics.Type_0_has_no_signatures_for_which_the_type_argument_list_is_applicable, typeToString(errorType))); + } + return result; + + function getInstantiatedType(type: Type): Type { + let hasSignatures = false; + let hasApplicableSignature = false; + const result = getInstantiatedTypePart(type); + hasSomeApplicableSignature ||= hasApplicableSignature; + if (hasSignatures && !hasApplicableSignature) { + nonApplicableType ??= type; + } + return result; + + function getInstantiatedTypePart(type: Type): Type { + if (type.flags & TypeFlags.Object) { + const resolved = resolveStructuredTypeMembers(type as ObjectType); + const callSignatures = getInstantiatedSignatures(resolved.callSignatures); + const constructSignatures = getInstantiatedSignatures(resolved.constructSignatures); + hasSignatures ||= resolved.callSignatures.length !== 0 || resolved.constructSignatures.length !== 0; + hasApplicableSignature ||= callSignatures.length !== 0 || constructSignatures.length !== 0; + if (callSignatures !== resolved.callSignatures || constructSignatures !== resolved.constructSignatures) { + const result = createAnonymousType(createSymbol(SymbolFlags.None, InternalSymbolName.InstantiationExpression), resolved.members, callSignatures, constructSignatures, resolved.indexInfos) as ResolvedType & InstantiationExpressionType; + result.objectFlags |= ObjectFlags.InstantiationExpressionType; + result.node = node; + return result; + } + } + else if (type.flags & TypeFlags.InstantiableNonPrimitive) { + const constraint = getBaseConstraintOfType(type); + if (constraint) { + const instantiated = getInstantiatedTypePart(constraint); + if (instantiated !== constraint) { + return instantiated; + } + } + } + else if (type.flags & TypeFlags.Union) { + return mapType(type, getInstantiatedType); + } + else if (type.flags & TypeFlags.Intersection) { + return getIntersectionType(sameMap((type as IntersectionType).types, getInstantiatedTypePart)); + } + return type; + } + } + + function getInstantiatedSignatures(signatures: readonly Signature[]) { + const applicableSignatures = filter(signatures, sig => !!sig.typeParameters && hasCorrectTypeArgumentArity(sig, typeArguments)); + return sameMap(applicableSignatures, sig => { + const typeArgumentTypes = checkTypeArguments(sig, typeArguments!, /*reportErrors*/ true); + return typeArgumentTypes ? getSignatureInstantiation(sig, typeArgumentTypes, isInJSFile(sig.declaration)) : sig; + }); + } + } + + function checkSatisfiesExpression(node: SatisfiesExpression) { + checkSourceElement(node.type); + return checkSatisfiesExpressionWorker(node.expression, node.type); + } + + function checkSatisfiesExpressionWorker(expression: Expression, target: TypeNode, checkMode?: CheckMode) { + const exprType = checkExpression(expression, checkMode); + const targetType = getTypeFromTypeNode(target); + if (isErrorType(targetType)) { + return targetType; + } + const errorNode = findAncestor(target.parent, n => n.kind === SyntaxKind.SatisfiesExpression || n.kind === SyntaxKind.JSDocSatisfiesTag); + checkTypeAssignableToAndOptionallyElaborate(exprType, targetType, errorNode, expression, Diagnostics.Type_0_does_not_satisfy_the_expected_type_1); + return exprType; + } + + function checkMetaProperty(node: MetaProperty): Type { + checkGrammarMetaProperty(node); + + if (node.keywordToken === SyntaxKind.NewKeyword) { + return checkNewTargetMetaProperty(node); + } + + if (node.keywordToken === SyntaxKind.ImportKeyword) { + return checkImportMetaProperty(node); + } + + return Debug.assertNever(node.keywordToken); + } + + function checkMetaPropertyKeyword(node: MetaProperty): Type { + switch (node.keywordToken) { + case SyntaxKind.ImportKeyword: + return getGlobalImportMetaExpressionType(); + case SyntaxKind.NewKeyword: + const type = checkNewTargetMetaProperty(node); + return isErrorType(type) ? errorType : createNewTargetExpressionType(type); + default: + Debug.assertNever(node.keywordToken); + } + } + + function checkNewTargetMetaProperty(node: MetaProperty) { + const container = getNewTargetContainer(node); + if (!container) { + error(node, Diagnostics.Meta_property_0_is_only_allowed_in_the_body_of_a_function_declaration_function_expression_or_constructor, "new.target"); + return errorType; + } + else if (container.kind === SyntaxKind.Constructor) { + const symbol = getSymbolOfDeclaration(container.parent); + return getTypeOfSymbol(symbol); + } + else { + const symbol = getSymbolOfDeclaration(container); + return getTypeOfSymbol(symbol); + } + } + + function checkImportMetaProperty(node: MetaProperty) { + if (moduleKind === ModuleKind.Node16 || moduleKind === ModuleKind.NodeNext) { + if (getSourceFileOfNode(node).impliedNodeFormat !== ModuleKind.ESNext) { + error(node, Diagnostics.The_import_meta_meta_property_is_not_allowed_in_files_which_will_build_into_CommonJS_output); + } + } + else if (moduleKind < ModuleKind.ES2020 && moduleKind !== ModuleKind.System) { + error(node, Diagnostics.The_import_meta_meta_property_is_only_allowed_when_the_module_option_is_es2020_es2022_esnext_system_node16_or_nodenext); + } + const file = getSourceFileOfNode(node); + Debug.assert(!!(file.flags & NodeFlags.PossiblyContainsImportMeta), "Containing file is missing import meta node flag."); + return node.name.escapedText === "meta" ? getGlobalImportMetaType() : errorType; + } + + function getTypeOfParameter(symbol: Symbol) { + const declaration = symbol.valueDeclaration; + return addOptionality( + getTypeOfSymbol(symbol), + /*isProperty*/ false, + /*isOptional*/ !!declaration && (hasInitializer(declaration) || isOptionalDeclaration(declaration)), + ); + } + + function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember): __String; + function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember | undefined, index: number, restParameterName?: __String): __String; + function getTupleElementLabel(d: ParameterDeclaration | NamedTupleMember | undefined, index?: number, restParameterName = "arg" as __String) { + if (!d) { + return `${restParameterName}_${index}` as __String; + } + Debug.assert(isIdentifier(d.name)); // Parameter declarations could be binding patterns, but we only allow identifier names + return d.name.escapedText; + } + + function getParameterNameAtPosition(signature: Signature, pos: number, overrideRestType?: Type) { + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + return signature.parameters[pos].escapedName; + } + const restParameter = signature.parameters[paramCount] || unknownSymbol; + const restType = overrideRestType || getTypeOfSymbol(restParameter); + if (isTupleType(restType)) { + const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; + const index = pos - paramCount; + return getTupleElementLabel(associatedNames?.[index], index, restParameter.escapedName); + } + return restParameter.escapedName; + } + + function getParameterIdentifierInfoAtPosition(signature: Signature, pos: number): { parameter: Identifier; parameterName: __String; isRestParameter: boolean; } | undefined { + if (signature.declaration?.kind === SyntaxKind.JSDocFunctionType) { + return undefined; + } + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + const param = signature.parameters[pos]; + const paramIdent = getParameterDeclarationIdentifier(param); + return paramIdent ? { + parameter: paramIdent, + parameterName: param.escapedName, + isRestParameter: false, + } : undefined; + } + + const restParameter = signature.parameters[paramCount] || unknownSymbol; + const restIdent = getParameterDeclarationIdentifier(restParameter); + if (!restIdent) { + return undefined; + } + + const restType = getTypeOfSymbol(restParameter); + if (isTupleType(restType)) { + const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; + const index = pos - paramCount; + const associatedName = associatedNames?.[index]; + const isRestTupleElement = !!associatedName?.dotDotDotToken; + + if (associatedName) { + Debug.assert(isIdentifier(associatedName.name)); + return { parameter: associatedName.name, parameterName: associatedName.name.escapedText, isRestParameter: isRestTupleElement }; + } + + return undefined; + } + + if (pos === paramCount) { + return { parameter: restIdent, parameterName: restParameter.escapedName, isRestParameter: true }; + } + return undefined; + } + + function getParameterDeclarationIdentifier(symbol: Symbol) { + return symbol.valueDeclaration && isParameter(symbol.valueDeclaration) && isIdentifier(symbol.valueDeclaration.name) && symbol.valueDeclaration.name; + } + function isValidDeclarationForTupleLabel(d: Declaration): d is NamedTupleMember | (ParameterDeclaration & { name: Identifier; }) { + return d.kind === SyntaxKind.NamedTupleMember || (isParameter(d) && d.name && isIdentifier(d.name)); + } + + function getNameableDeclarationAtPosition(signature: Signature, pos: number) { + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + const decl = signature.parameters[pos].valueDeclaration; + return decl && isValidDeclarationForTupleLabel(decl) ? decl : undefined; + } + const restParameter = signature.parameters[paramCount] || unknownSymbol; + const restType = getTypeOfSymbol(restParameter); + if (isTupleType(restType)) { + const associatedNames = ((restType as TypeReference).target as TupleType).labeledElementDeclarations; + const index = pos - paramCount; + return associatedNames && associatedNames[index]; + } + return restParameter.valueDeclaration && isValidDeclarationForTupleLabel(restParameter.valueDeclaration) ? restParameter.valueDeclaration : undefined; + } + + function getTypeAtPosition(signature: Signature, pos: number): Type { + return tryGetTypeAtPosition(signature, pos) || anyType; + } + + function tryGetTypeAtPosition(signature: Signature, pos: number): Type | undefined { + const paramCount = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + if (pos < paramCount) { + return getTypeOfParameter(signature.parameters[pos]); + } + if (signatureHasRestParameter(signature)) { + // We want to return the value undefined for an out of bounds parameter position, + // so we need to check bounds here before calling getIndexedAccessType (which + // otherwise would return the type 'undefined'). + const restType = getTypeOfSymbol(signature.parameters[paramCount]); + const index = pos - paramCount; + if (!isTupleType(restType) || restType.target.combinedFlags & ElementFlags.Variable || index < restType.target.fixedLength) { + return getIndexedAccessType(restType, getNumberLiteralType(index)); + } + } + return undefined; + } + + function getRestTypeAtPosition(source: Signature, pos: number, readonly?: boolean): Type { + const parameterCount = getParameterCount(source); + const minArgumentCount = getMinArgumentCount(source); + const restType = getEffectiveRestType(source); + if (restType && pos >= parameterCount - 1) { + return pos === parameterCount - 1 ? restType : createArrayType(getIndexedAccessType(restType, numberType)); + } + const types = []; + const flags = []; + const names = []; + for (let i = pos; i < parameterCount; i++) { + if (!restType || i < parameterCount - 1) { + types.push(getTypeAtPosition(source, i)); + flags.push(i < minArgumentCount ? ElementFlags.Required : ElementFlags.Optional); + } + else { + types.push(restType); + flags.push(ElementFlags.Variadic); + } + names.push(getNameableDeclarationAtPosition(source, i)); + } + return createTupleType(types, flags, readonly, names); + } + + // Return the rest type at the given position, transforming `any[]` into just `any`. We do this because + // in signatures we want `any[]` in a rest position to be compatible with anything, but `any[]` isn't + // assignable to tuple types with required elements. + function getRestOrAnyTypeAtPosition(source: Signature, pos: number): Type { + const restType = getRestTypeAtPosition(source, pos); + const elementType = restType && getElementTypeOfArrayType(restType); + return elementType && isTypeAny(elementType) ? anyType : restType; + } + + // Return the number of parameters in a signature. The rest parameter, if present, counts as one + // parameter. For example, the parameter count of (x: number, y: number, ...z: string[]) is 3 and + // the parameter count of (x: number, ...args: [number, ...string[], boolean])) is also 3. In the + // latter example, the effective rest type is [...string[], boolean]. + function getParameterCount(signature: Signature) { + const length = signature.parameters.length; + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[length - 1]); + if (isTupleType(restType)) { + return length + restType.target.fixedLength - (restType.target.combinedFlags & ElementFlags.Variable ? 0 : 1); + } + } + return length; + } + + function getMinArgumentCount(signature: Signature, flags?: MinArgumentCountFlags) { + const strongArityForUntypedJS = flags! & MinArgumentCountFlags.StrongArityForUntypedJS; + const voidIsNonOptional = flags! & MinArgumentCountFlags.VoidIsNonOptional; + if (voidIsNonOptional || signature.resolvedMinArgumentCount === undefined) { + let minArgumentCount: number | undefined; + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + if (isTupleType(restType)) { + const firstOptionalIndex = findIndex(restType.target.elementFlags, f => !(f & ElementFlags.Required)); + const requiredCount = firstOptionalIndex < 0 ? restType.target.fixedLength : firstOptionalIndex; + if (requiredCount > 0) { + minArgumentCount = signature.parameters.length - 1 + requiredCount; + } + } + } + if (minArgumentCount === undefined) { + if (!strongArityForUntypedJS && signature.flags & SignatureFlags.IsUntypedSignatureInJSFile) { + return 0; + } + minArgumentCount = signature.minArgumentCount; + } + if (voidIsNonOptional) { + return minArgumentCount; + } + for (let i = minArgumentCount - 1; i >= 0; i--) { + const type = getTypeAtPosition(signature, i); + if (filterType(type, acceptsVoid).flags & TypeFlags.Never) { + break; + } + minArgumentCount = i; + } + signature.resolvedMinArgumentCount = minArgumentCount; + } + return signature.resolvedMinArgumentCount; + } + + function hasEffectiveRestParameter(signature: Signature) { + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + return !isTupleType(restType) || !!(restType.target.combinedFlags & ElementFlags.Variable); + } + return false; + } + + function getEffectiveRestType(signature: Signature) { + if (signatureHasRestParameter(signature)) { + const restType = getTypeOfSymbol(signature.parameters[signature.parameters.length - 1]); + if (!isTupleType(restType)) { + return isTypeAny(restType) ? anyArrayType : restType; + } + if (restType.target.combinedFlags & ElementFlags.Variable) { + return sliceTupleType(restType, restType.target.fixedLength); + } + } + return undefined; + } + + function getNonArrayRestType(signature: Signature) { + const restType = getEffectiveRestType(signature); + return restType && !isArrayType(restType) && !isTypeAny(restType) ? restType : undefined; + } + + function getTypeOfFirstParameterOfSignature(signature: Signature) { + return getTypeOfFirstParameterOfSignatureWithFallback(signature, neverType); + } + + function getTypeOfFirstParameterOfSignatureWithFallback(signature: Signature, fallbackType: Type) { + return signature.parameters.length > 0 ? getTypeAtPosition(signature, 0) : fallbackType; + } + + function inferFromAnnotatedParameters(signature: Signature, context: Signature, inferenceContext: InferenceContext) { + const len = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + for (let i = 0; i < len; i++) { + const declaration = signature.parameters[i].valueDeclaration as ParameterDeclaration; + const typeNode = getEffectiveTypeAnnotationNode(declaration); + if (typeNode) { + const source = addOptionality(getTypeFromTypeNode(typeNode), /*isProperty*/ false, isOptionalDeclaration(declaration)); + const target = getTypeAtPosition(context, i); + inferTypes(inferenceContext.inferences, source, target); + } + } + } + + function assignContextualParameterTypes(signature: Signature, context: Signature) { + if (context.typeParameters) { + if (!signature.typeParameters) { + signature.typeParameters = context.typeParameters; + } + else { + return; // This signature has already has a contextual inference performed and cached on it! + } + } + if (context.thisParameter) { + const parameter = signature.thisParameter; + if (!parameter || parameter.valueDeclaration && !(parameter.valueDeclaration as ParameterDeclaration).type) { + if (!parameter) { + signature.thisParameter = createSymbolWithType(context.thisParameter, /*type*/ undefined); + } + assignParameterType(signature.thisParameter!, getTypeOfSymbol(context.thisParameter)); + } + } + const len = signature.parameters.length - (signatureHasRestParameter(signature) ? 1 : 0); + for (let i = 0; i < len; i++) { + const parameter = signature.parameters[i]; + const declaration = parameter.valueDeclaration as ParameterDeclaration; + if (!getEffectiveTypeAnnotationNode(declaration)) { + let type = tryGetTypeAtPosition(context, i); + if (type && declaration.initializer) { + let initializerType = checkDeclarationInitializer(declaration, CheckMode.Normal); + if (!isTypeAssignableTo(initializerType, type) && isTypeAssignableTo(type, initializerType = widenTypeInferredFromInitializer(declaration, initializerType))) { + type = initializerType; + } + } + assignParameterType(parameter, type); + } + } + if (signatureHasRestParameter(signature)) { + // parameter might be a transient symbol generated by use of `arguments` in the function body. + const parameter = last(signature.parameters); + if ( + parameter.valueDeclaration + ? !getEffectiveTypeAnnotationNode(parameter.valueDeclaration as ParameterDeclaration) + // a declarationless parameter may still have a `.type` already set by its construction logic + // (which may pull a type from a jsdoc) - only allow fixing on `DeferredType` parameters with a fallback type + : !!(getCheckFlags(parameter) & CheckFlags.DeferredType) + ) { + const contextualParameterType = getRestTypeAtPosition(context, len); + assignParameterType(parameter, contextualParameterType); + } + } + } + + function assignNonContextualParameterTypes(signature: Signature) { + if (signature.thisParameter) { + assignParameterType(signature.thisParameter); + } + for (const parameter of signature.parameters) { + assignParameterType(parameter); + } + } + + function assignParameterType(parameter: Symbol, contextualType?: Type) { + const links = getSymbolLinks(parameter); + if (!links.type) { + const declaration = parameter.valueDeclaration as ParameterDeclaration | undefined; + links.type = addOptionality( + contextualType || (declaration ? getWidenedTypeForVariableLikeDeclaration(declaration, /*reportErrors*/ true) : getTypeOfSymbol(parameter)), + /*isProperty*/ false, + /*isOptional*/ !!declaration && !declaration.initializer && isOptionalDeclaration(declaration), + ); + if (declaration && declaration.name.kind !== SyntaxKind.Identifier) { + // if inference didn't come up with anything but unknown, fall back to the binding pattern if present. + if (links.type === unknownType) { + links.type = getTypeFromBindingPattern(declaration.name); + } + assignBindingElementTypes(declaration.name, links.type); + } + } + else if (contextualType) { + Debug.assertEqual(links.type, contextualType, "Parameter symbol already has a cached type which differs from newly assigned type"); + } + } + + // When contextual typing assigns a type to a parameter that contains a binding pattern, we also need to push + // the destructured type into the contained binding elements. + function assignBindingElementTypes(pattern: BindingPattern, parentType: Type) { + for (const element of pattern.elements) { + if (!isOmittedExpression(element)) { + const type = getBindingElementTypeFromParentType(element, parentType, /*noTupleBoundsCheck*/ false); + if (element.name.kind === SyntaxKind.Identifier) { + getSymbolLinks(getSymbolOfDeclaration(element)).type = type; + } + else { + assignBindingElementTypes(element.name, type); + } + } + } + } + + function createClassDecoratorContextType(classType: Type) { + return tryCreateTypeReference(getGlobalClassDecoratorContextType(/*reportErrors*/ true), [classType]); + } + + function createClassMethodDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassMethodDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassGetterDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassGetterDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassSetterDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassSetterDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassAccessorDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassAccessorDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassFieldDecoratorContextType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassFieldDecoratorContextType(/*reportErrors*/ true), [thisType, valueType]); + } + + /** + * Gets a type like `{ name: "foo", private: false, static: true }` that is used to provided member-specific + * details that will be intersected with a decorator context type. + */ + function getClassMemberDecoratorContextOverrideType(nameType: Type, isPrivate: boolean, isStatic: boolean) { + const key = `${isPrivate ? "p" : "P"}${isStatic ? "s" : "S"}${nameType.id}` as const; + let overrideType = decoratorContextOverrideTypeCache.get(key); + if (!overrideType) { + const members = createSymbolTable(); + members.set("name" as __String, createProperty("name" as __String, nameType)); + members.set("private" as __String, createProperty("private" as __String, isPrivate ? trueType : falseType)); + members.set("static" as __String, createProperty("static" as __String, isStatic ? trueType : falseType)); + overrideType = createAnonymousType(/*symbol*/ undefined, members, emptyArray, emptyArray, emptyArray); + decoratorContextOverrideTypeCache.set(key, overrideType); + } + return overrideType; + } + + function createClassMemberDecoratorContextTypeForNode(node: MethodDeclaration | AccessorDeclaration | PropertyDeclaration, thisType: Type, valueType: Type) { + const isStatic = hasStaticModifier(node); + const isPrivate = isPrivateIdentifier(node.name); + const nameType = isPrivate ? getStringLiteralType(idText(node.name)) : getLiteralTypeFromPropertyName(node.name); + const contextType = isMethodDeclaration(node) ? createClassMethodDecoratorContextType(thisType, valueType) : + isGetAccessorDeclaration(node) ? createClassGetterDecoratorContextType(thisType, valueType) : + isSetAccessorDeclaration(node) ? createClassSetterDecoratorContextType(thisType, valueType) : + isAutoAccessorPropertyDeclaration(node) ? createClassAccessorDecoratorContextType(thisType, valueType) : + isPropertyDeclaration(node) ? createClassFieldDecoratorContextType(thisType, valueType) : + Debug.failBadSyntaxKind(node); + const overrideType = getClassMemberDecoratorContextOverrideType(nameType, isPrivate, isStatic); + return getIntersectionType([contextType, overrideType]); + } + + function createClassAccessorDecoratorTargetType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassAccessorDecoratorTargetType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassAccessorDecoratorResultType(thisType: Type, valueType: Type) { + return tryCreateTypeReference(getGlobalClassAccessorDecoratorResultType(/*reportErrors*/ true), [thisType, valueType]); + } + + function createClassFieldDecoratorInitializerMutatorType(thisType: Type, valueType: Type) { + const thisParam = createParameter("this" as __String, thisType); + const valueParam = createParameter("value" as __String, valueType); + return createFunctionType(/*typeParameters*/ undefined, thisParam, [valueParam], valueType, /*typePredicate*/ undefined, 1); + } + + /** + * Creates a call signature for an ES Decorator. This method is used by the semantics of + * `getESDecoratorCallSignature`, which you should probably be using instead. + */ + function createESDecoratorCallSignature(targetType: Type, contextType: Type, nonOptionalReturnType: Type) { + const targetParam = createParameter("target" as __String, targetType); + const contextParam = createParameter("context" as __String, contextType); + const returnType = getUnionType([nonOptionalReturnType, voidType]); + return createCallSignature(/*typeParameters*/ undefined, /*thisParameter*/ undefined, [targetParam, contextParam], returnType); + } + + /** + * Gets a call signature that should be used when resolving `decorator` as a call. This does not use the value + * of the decorator itself, but instead uses the declaration on which it is placed along with its relative + * position amongst other decorators on the same declaration to determine the applicable signature. The + * resulting signature can be used for call resolution, inference, and contextual typing. + */ + function getESDecoratorCallSignature(decorator: Decorator) { + // We are considering a future change that would allow the type of a decorator to affect the type of the + // class and its members, such as a `@Stringify` decorator changing the type of a `number` field to `string`, or + // a `@Callable` decorator adding a call signature to a `class`. The type arguments for the various context + // types may eventually change to reflect such mutations. + // + // In some cases we describe such potential mutations as coming from a "prior decorator application". It is + // important to note that, while decorators are *evaluated* left to right, they are *applied* right to left + // to preserve f ৹ g -> f(g(x)) application order. In these cases, a "prior" decorator usually means the + // next decorator following this one in document order. + // + // The "original type" of a class or member is the type it was declared as, or the type we infer from + // initializers, before _any_ decorators are applied. + // + // The type of a class or member that is a result of a prior decorator application represents the + // "current type", i.e., the type for the declaration at the time the decorator is _applied_. + // + // The type of a class or member that is the result of the application of *all* relevant decorators is the + // "final type". + // + // Any decorator that allows mutation or replacement will also refer to an "input type" and an + // "output type". The "input type" corresponds to the "current type" of the declaration, while the + // "output type" will become either the "input type/current type" for a subsequent decorator application, + // or the "final type" for the decorated declaration. + // + // It is important to understand decorator application order as it relates to how the "current", "input", + // "output", and "final" types will be determined: + // + // @E2 @E1 class SomeClass { + // @A2 @A1 static f() {} + // @B2 @B1 g() {} + // @C2 @C1 static x; + // @D2 @D1 y; + // } + // + // Per [the specification][1], decorators are applied in the following order: + // + // 1. For each static method (incl. get/set methods and `accessor` fields), in document order: + // a. Apply each decorator for that method, in reverse order (`A1`, `A2`). + // 2. For each instance method (incl. get/set methods and `accessor` fields), in document order: + // a. Apply each decorator for that method, in reverse order (`B1`, `B2`). + // 3. For each static field (excl. auto-accessors), in document order: + // a. Apply each decorator for that field, in reverse order (`C1`, `C2`). + // 4. For each instance field (excl. auto-accessors), in document order: + // a. Apply each decorator for that field, in reverse order (`D1`, `D2`). + // 5. Apply each decorator for the class, in reverse order (`E1`, `E2`). + // + // As a result, "current" types at each decorator application are as follows: + // - For `A1`, the "current" types of the class and method are their "original" types. + // - For `A2`, the "current type" of the method is the "output type" of `A1`, and the "current type" of the + // class is the type of `SomeClass` where `f` is the "output type" of `A1`. This becomes the "final type" + // of `f`. + // - For `B1`, the "current type" of the method is its "original type", and the "current type" of the class + // is the type of `SomeClass` where `f` now has its "final type". + // - etc. + // + // [1]: https://arai-a.github.io/ecma262-compare/?pr=2417&id=sec-runtime-semantics-classdefinitionevaluation + // + // This seems complicated at first glance, but is not unlike our existing inference for functions: + // + // declare function pipe( + // original: Original, + // a1: (input: Original, context: Context) => A1, + // a2: (input: A1, context: Context) => A2, + // b1: (input: A2, context: Context) => B1, + // b2: (input: B1, context: Context) => B2, + // c1: (input: B2, context: Context) => C1, + // c2: (input: C1, context: Context) => C2, + // d1: (input: C2, context: Context) => D1, + // d2: (input: D1, context: Context) => D2, + // e1: (input: D2, context: Context) => E1, + // e2: (input: E1, context: Context) => E2, + // ): E2; + + // When a decorator is applied, it is passed two arguments: "target", which is a value representing the + // thing being decorated (constructors for classes, functions for methods/accessors, `undefined` for fields, + // and a `{ get, set }` object for auto-accessors), and "context", which is an object that provides + // reflection information about the decorated element, as well as the ability to add additional "extra" + // initializers. In most cases, the "target" argument corresponds to the "input type" in some way, and the + // return value similarly corresponds to the "output type" (though if the "output type" is `void` or + // `undefined` then the "output type" is the "input type"). + + const { parent } = decorator; + const links = getNodeLinks(parent); + if (!links.decoratorSignature) { + links.decoratorSignature = anySignature; + switch (parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: { + // Class decorators have a `context` of `ClassDecoratorContext`, where the `Class` type + // argument will be the "final type" of the class after all decorators are applied. + + const node = parent as ClassDeclaration | ClassExpression; + const targetType = getTypeOfSymbol(getSymbolOfDeclaration(node)); + const contextType = createClassDecoratorContextType(targetType); + links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, targetType); + break; + } + + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: { + const node = parent as MethodDeclaration | GetAccessorDeclaration | SetAccessorDeclaration; + if (!isClassLike(node.parent)) break; + + // Method decorators have a `context` of `ClassMethodDecoratorContext`, where the + // `Value` type argument corresponds to the "final type" of the method. + // + // Getter decorators have a `context` of `ClassGetterDecoratorContext`, where the + // `Value` type argument corresponds to the "final type" of the value returned by the getter. + // + // Setter decorators have a `context` of `ClassSetterDecoratorContext`, where the + // `Value` type argument corresponds to the "final type" of the parameter of the setter. + // + // In all three cases, the `This` type argument is the "final type" of either the class or + // instance, depending on whether the member was `static`. + + const valueType = isMethodDeclaration(node) ? getOrCreateTypeFromSignature(getSignatureFromDeclaration(node)) : + getTypeOfNode(node); + + const thisType = hasStaticModifier(node) ? + getTypeOfSymbol(getSymbolOfDeclaration(node.parent)) : + getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node.parent)); + + // We wrap the "input type", if necessary, to match the decoration target. For getters this is + // something like `() => inputType`, for setters it's `(value: inputType) => void` and for + // methods it is just the input type. + const targetType = isGetAccessorDeclaration(node) ? createGetterFunctionType(valueType) : + isSetAccessorDeclaration(node) ? createSetterFunctionType(valueType) : + valueType; + + const contextType = createClassMemberDecoratorContextTypeForNode(node, thisType, valueType); + + // We also wrap the "output type", as needed. + const returnType = isGetAccessorDeclaration(node) ? createGetterFunctionType(valueType) : + isSetAccessorDeclaration(node) ? createSetterFunctionType(valueType) : + valueType; + + links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, returnType); + break; + } + + case SyntaxKind.PropertyDeclaration: { + const node = parent as PropertyDeclaration; + if (!isClassLike(node.parent)) break; + + // Field decorators have a `context` of `ClassFieldDecoratorContext` and + // auto-accessor decorators have a `context` of `ClassAccessorDecoratorContext. In + // both cases, the `This` type argument is the "final type" of either the class or instance, + // depending on whether the member was `static`, and the `Value` type argument corresponds to + // the "final type" of the value stored in the field. + + const valueType = getTypeOfNode(node); + const thisType = hasStaticModifier(node) ? + getTypeOfSymbol(getSymbolOfDeclaration(node.parent)) : + getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(node.parent)); + + // The `target` of an auto-accessor decorator is a `{ get, set }` object, representing the + // runtime-generated getter and setter that are added to the class/prototype. The `target` of a + // regular field decorator is always `undefined` as it isn't installed until it is initialized. + const targetType = hasAccessorModifier(node) ? createClassAccessorDecoratorTargetType(thisType, valueType) : + undefinedType; + + const contextType = createClassMemberDecoratorContextTypeForNode(node, thisType, valueType); + + // We wrap the "output type" depending on the declaration. For auto-accessors, we wrap the + // "output type" in a `ClassAccessorDecoratorResult` type, which allows for + // mutation of the runtime-generated getter and setter, as well as the injection of an + // initializer mutator. For regular fields, we wrap the "output type" in an initializer mutator. + const returnType = hasAccessorModifier(node) ? createClassAccessorDecoratorResultType(thisType, valueType) : + createClassFieldDecoratorInitializerMutatorType(thisType, valueType); + + links.decoratorSignature = createESDecoratorCallSignature(targetType, contextType, returnType); + break; + } + } + } + return links.decoratorSignature === anySignature ? undefined : links.decoratorSignature; + } + + function getLegacyDecoratorCallSignature(decorator: Decorator) { + const { parent } = decorator; + const links = getNodeLinks(parent); + if (!links.decoratorSignature) { + links.decoratorSignature = anySignature; + switch (parent.kind) { + case SyntaxKind.ClassDeclaration: + case SyntaxKind.ClassExpression: { + const node = parent as ClassDeclaration | ClassExpression; + // For a class decorator, the `target` is the type of the class (e.g. the + // "static" or "constructor" side of the class). + const targetType = getTypeOfSymbol(getSymbolOfDeclaration(node)); + const targetParam = createParameter("target" as __String, targetType); + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam], + getUnionType([targetType, voidType]), + ); + break; + } + case SyntaxKind.Parameter: { + const node = parent as ParameterDeclaration; + if ( + !isConstructorDeclaration(node.parent) && + !(isMethodDeclaration(node.parent) || isSetAccessorDeclaration(node.parent) && isClassLike(node.parent.parent)) + ) { + break; + } + + if (getThisParameter(node.parent) === node) { + break; + } + + const index = getThisParameter(node.parent) ? + node.parent.parameters.indexOf(node) - 1 : + node.parent.parameters.indexOf(node); + Debug.assert(index >= 0); + + // A parameter declaration decorator will have three arguments (see `ParameterDecorator` in + // core.d.ts). + + const targetType = isConstructorDeclaration(node.parent) ? getTypeOfSymbol(getSymbolOfDeclaration(node.parent.parent)) : + getParentTypeOfClassElement(node.parent); + + const keyType = isConstructorDeclaration(node.parent) ? undefinedType : + getClassElementPropertyKeyType(node.parent); + + const indexType = getNumberLiteralType(index); + + const targetParam = createParameter("target" as __String, targetType); + const keyParam = createParameter("propertyKey" as __String, keyType); + const indexParam = createParameter("parameterIndex" as __String, indexType); + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam, keyParam, indexParam], + voidType, + ); + break; + } + case SyntaxKind.MethodDeclaration: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + case SyntaxKind.PropertyDeclaration: { + const node = parent as MethodDeclaration | AccessorDeclaration | PropertyDeclaration; + if (!isClassLike(node.parent)) break; + + // A method or accessor declaration decorator will have either two or three arguments (see + // `PropertyDecorator` and `MethodDecorator` in core.d.ts). + + const targetType = getParentTypeOfClassElement(node); + const targetParam = createParameter("target" as __String, targetType); + + const keyType = getClassElementPropertyKeyType(node); + const keyParam = createParameter("propertyKey" as __String, keyType); + + const returnType = isPropertyDeclaration(node) ? voidType : + createTypedPropertyDescriptorType(getTypeOfNode(node)); + + const hasPropDesc = !isPropertyDeclaration(parent) || hasAccessorModifier(parent); + if (hasPropDesc) { + const descriptorType = createTypedPropertyDescriptorType(getTypeOfNode(node)); + const descriptorParam = createParameter("descriptor" as __String, descriptorType); + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam, keyParam, descriptorParam], + getUnionType([returnType, voidType]), + ); + } + else { + links.decoratorSignature = createCallSignature( + /*typeParameters*/ undefined, + /*thisParameter*/ undefined, + [targetParam, keyParam], + getUnionType([returnType, voidType]), + ); + } + break; + } + } + } + return links.decoratorSignature === anySignature ? undefined : links.decoratorSignature; + } + + function getDecoratorCallSignature(decorator: Decorator) { + return legacyDecorators ? getLegacyDecoratorCallSignature(decorator) : + getESDecoratorCallSignature(decorator); + } + + function createPromiseType(promisedType: Type): Type { + // creates a `Promise` type where `T` is the promisedType argument + const globalPromiseType = getGlobalPromiseType(/*reportErrors*/ true); + if (globalPromiseType !== emptyGenericType) { + // if the promised type is itself a promise, get the underlying type; otherwise, fallback to the promised type + // Unwrap an `Awaited` to `T` to improve inference. + promisedType = getAwaitedTypeNoAlias(unwrapAwaitedType(promisedType)) || unknownType; + return createTypeReference(globalPromiseType, [promisedType]); + } + + return unknownType; + } + + function createPromiseLikeType(promisedType: Type): Type { + // creates a `PromiseLike` type where `T` is the promisedType argument + const globalPromiseLikeType = getGlobalPromiseLikeType(/*reportErrors*/ true); + if (globalPromiseLikeType !== emptyGenericType) { + // if the promised type is itself a promise, get the underlying type; otherwise, fallback to the promised type + // Unwrap an `Awaited` to `T` to improve inference. + promisedType = getAwaitedTypeNoAlias(unwrapAwaitedType(promisedType)) || unknownType; + return createTypeReference(globalPromiseLikeType, [promisedType]); + } + + return unknownType; + } + + function createPromiseReturnType(func: FunctionLikeDeclaration | ImportCall, promisedType: Type) { + const promiseType = createPromiseType(promisedType); + if (promiseType === unknownType) { + error( + func, + isImportCall(func) ? + Diagnostics.A_dynamic_import_call_returns_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option : + Diagnostics.An_async_function_or_method_must_return_a_Promise_Make_sure_you_have_a_declaration_for_Promise_or_include_ES2015_in_your_lib_option, + ); + return errorType; + } + else if (!getGlobalPromiseConstructorSymbol(/*reportErrors*/ true)) { + error( + func, + isImportCall(func) ? + Diagnostics.A_dynamic_import_call_in_ES5_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option : + Diagnostics.An_async_function_or_method_in_ES5_requires_the_Promise_constructor_Make_sure_you_have_a_declaration_for_the_Promise_constructor_or_include_ES2015_in_your_lib_option, + ); + } + + return promiseType; + } + + function createNewTargetExpressionType(targetType: Type): Type { + // Create a synthetic type `NewTargetExpression { target: TargetType; }` + const symbol = createSymbol(SymbolFlags.None, "NewTargetExpression" as __String); + + const targetPropertySymbol = createSymbol(SymbolFlags.Property, "target" as __String, CheckFlags.Readonly); + targetPropertySymbol.parent = symbol; + targetPropertySymbol.links.type = targetType; + + const members = createSymbolTable([targetPropertySymbol]); + symbol.members = members; + return createAnonymousType(symbol, members, emptyArray, emptyArray, emptyArray); + } + + function getReturnTypeFromBody(func: FunctionLikeDeclaration, checkMode?: CheckMode): Type { + if (!func.body) { + return errorType; + } + + const functionFlags = getFunctionFlags(func); + const isAsync = (functionFlags & FunctionFlags.Async) !== 0; + const isGenerator = (functionFlags & FunctionFlags.Generator) !== 0; + + let returnType: Type | undefined; + let yieldType: Type | undefined; + let nextType: Type | undefined; + let fallbackReturnType: Type = voidType; + if (func.body.kind !== SyntaxKind.Block) { // Async or normal arrow function + returnType = checkExpressionCached(func.body, checkMode && checkMode & ~CheckMode.SkipGenericFunctions); + if (isAsync) { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so the + // return type of the body should be unwrapped to its awaited type, which we will wrap in + // the native Promise type later in this function. + returnType = unwrapAwaitedType(checkAwaitedType(returnType, /*withAlias*/ false, /*errorNode*/ func, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member)); + } + } + else if (isGenerator) { // Generator or AsyncGenerator function + const returnTypes = checkAndAggregateReturnExpressionTypes(func, checkMode); + if (!returnTypes) { + fallbackReturnType = neverType; + } + else if (returnTypes.length > 0) { + returnType = getUnionType(returnTypes, UnionReduction.Subtype); + } + const { yieldTypes, nextTypes } = checkAndAggregateYieldOperandTypes(func, checkMode); + yieldType = some(yieldTypes) ? getUnionType(yieldTypes, UnionReduction.Subtype) : undefined; + nextType = some(nextTypes) ? getIntersectionType(nextTypes) : undefined; + } + else { // Async or normal function + const types = checkAndAggregateReturnExpressionTypes(func, checkMode); + if (!types) { + // For an async function, the return type will not be never, but rather a Promise for never. + return functionFlags & FunctionFlags.Async + ? createPromiseReturnType(func, neverType) // Async function + : neverType; // Normal function + } + if (types.length === 0) { + // For an async function, the return type will not be void/undefined, but rather a Promise for void/undefined. + const contextualReturnType = getContextualReturnType(func, /*contextFlags*/ undefined); + const returnType = contextualReturnType && (unwrapReturnType(contextualReturnType, functionFlags) || voidType).flags & TypeFlags.Undefined ? undefinedType : voidType; + return functionFlags & FunctionFlags.Async ? createPromiseReturnType(func, returnType) : // Async function + returnType; // Normal function + } + + // Return a union of the return expression types. + returnType = getUnionType(types, UnionReduction.Subtype); + } + + if (returnType || yieldType || nextType) { + if (yieldType) reportErrorsFromWidening(func, yieldType, WideningKind.GeneratorYield); + if (returnType) reportErrorsFromWidening(func, returnType, WideningKind.FunctionReturn); + if (nextType) reportErrorsFromWidening(func, nextType, WideningKind.GeneratorNext); + if ( + returnType && isUnitType(returnType) || + yieldType && isUnitType(yieldType) || + nextType && isUnitType(nextType) + ) { + const contextualSignature = getContextualSignatureForFunctionLikeDeclaration(func); + const contextualType = !contextualSignature ? undefined : + contextualSignature === getSignatureFromDeclaration(func) ? isGenerator ? undefined : returnType : + instantiateContextualType(getReturnTypeOfSignature(contextualSignature), func, /*contextFlags*/ undefined); + if (isGenerator) { + yieldType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(yieldType, contextualType, IterationTypeKind.Yield, isAsync); + returnType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(returnType, contextualType, IterationTypeKind.Return, isAsync); + nextType = getWidenedLiteralLikeTypeForContextualIterationTypeIfNeeded(nextType, contextualType, IterationTypeKind.Next, isAsync); + } + else { + returnType = getWidenedLiteralLikeTypeForContextualReturnTypeIfNeeded(returnType, contextualType, isAsync); + } + } + + if (yieldType) yieldType = getWidenedType(yieldType); + if (returnType) returnType = getWidenedType(returnType); + if (nextType) nextType = getWidenedType(nextType); + } + + if (isGenerator) { + return createGeneratorType( + yieldType || neverType, + returnType || fallbackReturnType, + nextType || getContextualIterationType(IterationTypeKind.Next, func) || unknownType, + isAsync, + ); + } + else { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so the + // return type of the body is awaited type of the body, wrapped in a native Promise type. + return isAsync + ? createPromiseType(returnType || fallbackReturnType) + : returnType || fallbackReturnType; + } + } + + function createGeneratorType(yieldType: Type, returnType: Type, nextType: Type, isAsyncGenerator: boolean) { + const resolver = isAsyncGenerator ? asyncIterationTypesResolver : syncIterationTypesResolver; + const globalGeneratorType = resolver.getGlobalGeneratorType(/*reportErrors*/ false); + yieldType = resolver.resolveIterationType(yieldType, /*errorNode*/ undefined) || unknownType; + returnType = resolver.resolveIterationType(returnType, /*errorNode*/ undefined) || unknownType; + nextType = resolver.resolveIterationType(nextType, /*errorNode*/ undefined) || unknownType; + if (globalGeneratorType === emptyGenericType) { + // Fall back to the global IterableIterator if returnType is assignable to the expected return iteration + // type of IterableIterator, and the expected next iteration type of IterableIterator is assignable to + // nextType. + const globalType = resolver.getGlobalIterableIteratorType(/*reportErrors*/ false); + const iterationTypes = globalType !== emptyGenericType ? getIterationTypesOfGlobalIterableType(globalType, resolver) : undefined; + const iterableIteratorReturnType = iterationTypes ? iterationTypes.returnType : anyType; + const iterableIteratorNextType = iterationTypes ? iterationTypes.nextType : undefinedType; + if ( + isTypeAssignableTo(returnType, iterableIteratorReturnType) && + isTypeAssignableTo(iterableIteratorNextType, nextType) + ) { + if (globalType !== emptyGenericType) { + return createTypeFromGenericGlobalType(globalType, [yieldType]); + } + + // The global IterableIterator type doesn't exist, so report an error + resolver.getGlobalIterableIteratorType(/*reportErrors*/ true); + return emptyObjectType; + } + + // The global Generator type doesn't exist, so report an error + resolver.getGlobalGeneratorType(/*reportErrors*/ true); + return emptyObjectType; + } + + return createTypeFromGenericGlobalType(globalGeneratorType, [yieldType, returnType, nextType]); + } + + function checkAndAggregateYieldOperandTypes(func: FunctionLikeDeclaration, checkMode: CheckMode | undefined) { + const yieldTypes: Type[] = []; + const nextTypes: Type[] = []; + const isAsync = (getFunctionFlags(func) & FunctionFlags.Async) !== 0; + forEachYieldExpression(func.body as Block, yieldExpression => { + const yieldExpressionType = yieldExpression.expression ? checkExpression(yieldExpression.expression, checkMode) : undefinedWideningType; + pushIfUnique(yieldTypes, getYieldedTypeOfYieldExpression(yieldExpression, yieldExpressionType, anyType, isAsync)); + let nextType: Type | undefined; + if (yieldExpression.asteriskToken) { + const iterationTypes = getIterationTypesOfIterable( + yieldExpressionType, + isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar, + yieldExpression.expression, + ); + nextType = iterationTypes && iterationTypes.nextType; + } + else { + nextType = getContextualType(yieldExpression, /*contextFlags*/ undefined); + } + if (nextType) pushIfUnique(nextTypes, nextType); + }); + return { yieldTypes, nextTypes }; + } + + function getYieldedTypeOfYieldExpression(node: YieldExpression, expressionType: Type, sentType: Type, isAsync: boolean): Type | undefined { + const errorNode = node.expression || node; + // A `yield*` expression effectively yields everything that its operand yields + const yieldedType = node.asteriskToken ? checkIteratedTypeOrElementType(isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar, expressionType, sentType, errorNode) : expressionType; + return !isAsync ? yieldedType : getAwaitedType( + yieldedType, + errorNode, + node.asteriskToken + ? Diagnostics.Type_of_iterated_elements_of_a_yield_Asterisk_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member + : Diagnostics.Type_of_yield_operand_in_an_async_generator_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member, + ); + } + + // Return the combined not-equal type facts for all cases except those between the start and end indices. + function getNotEqualFactsFromTypeofSwitch(start: number, end: number, witnesses: (string | undefined)[]): TypeFacts { + let facts: TypeFacts = TypeFacts.None; + for (let i = 0; i < witnesses.length; i++) { + const witness = i < start || i >= end ? witnesses[i] : undefined; + facts |= witness !== undefined ? typeofNEFacts.get(witness) || TypeFacts.TypeofNEHostObject : 0; + } + return facts; + } + + function isExhaustiveSwitchStatement(node: SwitchStatement): boolean { + const links = getNodeLinks(node); + if (links.isExhaustive === undefined) { + links.isExhaustive = 0; // Indicate resolution is in process + const exhaustive = computeExhaustiveSwitchStatement(node); + if (links.isExhaustive === 0) { + links.isExhaustive = exhaustive; + } + } + else if (links.isExhaustive === 0) { + links.isExhaustive = false; // Resolve circularity to false + } + return links.isExhaustive; + } + + function computeExhaustiveSwitchStatement(node: SwitchStatement): boolean { + if (node.expression.kind === SyntaxKind.TypeOfExpression) { + const witnesses = getSwitchClauseTypeOfWitnesses(node); + if (!witnesses) { + return false; + } + const operandConstraint = getBaseConstraintOrType(checkExpressionCached((node.expression as TypeOfExpression).expression)); + // Get the not-equal flags for all handled cases. + const notEqualFacts = getNotEqualFactsFromTypeofSwitch(0, 0, witnesses); + if (operandConstraint.flags & TypeFlags.AnyOrUnknown) { + // We special case the top types to be exhaustive when all cases are handled. + return (TypeFacts.AllTypeofNE & notEqualFacts) === TypeFacts.AllTypeofNE; + } + // A missing not-equal flag indicates that the type wasn't handled by some case. + return !someType(operandConstraint, t => getTypeFacts(t, notEqualFacts) === notEqualFacts); + } + const type = checkExpressionCached(node.expression); + if (!isLiteralType(type)) { + return false; + } + const switchTypes = getSwitchClauseTypes(node); + if (!switchTypes.length || some(switchTypes, isNeitherUnitTypeNorNever)) { + return false; + } + return eachTypeContainedIn(mapType(type, getRegularTypeOfLiteralType), switchTypes); + } + + function functionHasImplicitReturn(func: FunctionLikeDeclaration) { + return func.endFlowNode && isReachableFlowNode(func.endFlowNode); + } + + /** NOTE: Return value of `[]` means a different thing than `undefined`. `[]` means func returns `void`, `undefined` means it returns `never`. */ + function checkAndAggregateReturnExpressionTypes(func: FunctionLikeDeclaration, checkMode: CheckMode | undefined): Type[] | undefined { + const functionFlags = getFunctionFlags(func); + const aggregatedTypes: Type[] = []; + let hasReturnWithNoExpression = functionHasImplicitReturn(func); + let hasReturnOfTypeNever = false; + forEachReturnStatement(func.body as Block, returnStatement => { + let expr = returnStatement.expression; + if (expr) { + expr = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + // Bare calls to this same function don't contribute to inference + // and `return await` is also safe to unwrap here + if (functionFlags & FunctionFlags.Async && expr.kind === SyntaxKind.AwaitExpression) { + expr = skipParentheses((expr as AwaitExpression).expression, /*excludeJSDocTypeAssertions*/ true); + } + if ( + expr.kind === SyntaxKind.CallExpression && + (expr as CallExpression).expression.kind === SyntaxKind.Identifier && + checkExpressionCached((expr as CallExpression).expression).symbol === getMergedSymbol(func.symbol) && + (!isFunctionExpressionOrArrowFunction(func.symbol.valueDeclaration!) || isConstantReference((expr as CallExpression).expression)) + ) { + hasReturnOfTypeNever = true; + return; + } + + let type = checkExpressionCached(expr, checkMode && checkMode & ~CheckMode.SkipGenericFunctions); + if (functionFlags & FunctionFlags.Async) { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so the + // return type of the body should be unwrapped to its awaited type, which should be wrapped in + // the native Promise type by the caller. + type = unwrapAwaitedType(checkAwaitedType(type, /*withAlias*/ false, func, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member)); + } + if (type.flags & TypeFlags.Never) { + hasReturnOfTypeNever = true; + } + pushIfUnique(aggregatedTypes, type); + } + else { + hasReturnWithNoExpression = true; + } + }); + if (aggregatedTypes.length === 0 && !hasReturnWithNoExpression && (hasReturnOfTypeNever || mayReturnNever(func))) { + return undefined; + } + if ( + strictNullChecks && aggregatedTypes.length && hasReturnWithNoExpression && + !(isJSConstructor(func) && aggregatedTypes.some(t => t.symbol === func.symbol)) + ) { + // Javascript "callable constructors", containing eg `if (!(this instanceof A)) return new A()` should not add undefined + pushIfUnique(aggregatedTypes, undefinedType); + } + return aggregatedTypes; + } + function mayReturnNever(func: FunctionLikeDeclaration): boolean { + switch (func.kind) { + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + return true; + case SyntaxKind.MethodDeclaration: + return func.parent.kind === SyntaxKind.ObjectLiteralExpression; + default: + return false; + } + } + + function getTypePredicateFromBody(func: FunctionLikeDeclaration): TypePredicate | undefined { + switch (func.kind) { + case SyntaxKind.Constructor: + case SyntaxKind.GetAccessor: + case SyntaxKind.SetAccessor: + return undefined; + } + const functionFlags = getFunctionFlags(func); + if (functionFlags !== FunctionFlags.Normal) return undefined; + + // Only attempt to infer a type predicate if there's exactly one return. + let singleReturn: Expression | undefined; + if (func.body && func.body.kind !== SyntaxKind.Block) { + singleReturn = func.body; // arrow function + } + else { + const bailedEarly = forEachReturnStatement(func.body as Block, returnStatement => { + if (singleReturn || !returnStatement.expression) return true; + singleReturn = returnStatement.expression; + }); + if (bailedEarly || !singleReturn || functionHasImplicitReturn(func)) return undefined; + } + return checkIfExpressionRefinesAnyParameter(func, singleReturn); + } + + function checkIfExpressionRefinesAnyParameter(func: FunctionLikeDeclaration, expr: Expression): TypePredicate | undefined { + expr = skipParentheses(expr, /*excludeJSDocTypeAssertions*/ true); + const returnType = checkExpressionCached(expr); + if (!(returnType.flags & TypeFlags.Boolean)) return undefined; + + return forEach(func.parameters, (param, i) => { + const initType = getTypeOfSymbol(param.symbol); + if (!initType || initType.flags & TypeFlags.Boolean || !isIdentifier(param.name) || isSymbolAssigned(param.symbol) || isRestParameter(param)) { + // Refining "x: boolean" to "x is true" or "x is false" isn't useful. + return; + } + const trueType = checkIfExpressionRefinesParameter(func, expr, param, initType); + if (trueType) { + return createTypePredicate(TypePredicateKind.Identifier, unescapeLeadingUnderscores(param.name.escapedText), i, trueType); + } + }); + } + + function checkIfExpressionRefinesParameter(func: FunctionLikeDeclaration, expr: Expression, param: ParameterDeclaration, initType: Type): Type | undefined { + const antecedent = (expr as Expression & { flowNode?: FlowNode; }).flowNode || + expr.parent.kind === SyntaxKind.ReturnStatement && (expr.parent as ReturnStatement).flowNode || + createFlowNode(FlowFlags.Start, /*node*/ undefined, /*antecedent*/ undefined); + const trueCondition = createFlowNode(FlowFlags.TrueCondition, expr, antecedent); + + const trueType = getFlowTypeOfReference(param.name, initType, initType, func, trueCondition); + if (trueType === initType) return undefined; + + // "x is T" means that x is T if and only if it returns true. If it returns false then x is not T. + // This means that if the function is called with an argument of type trueType, there can't be anything left in the `else` branch. It must reduce to `never`. + const falseCondition = createFlowNode(FlowFlags.FalseCondition, expr, antecedent); + const falseSubtype = getFlowTypeOfReference(param.name, initType, trueType, func, falseCondition); + return falseSubtype.flags & TypeFlags.Never ? trueType : undefined; + } + + /** + * TypeScript Specification 1.0 (6.3) - July 2014 + * An explicitly typed function whose return type isn't the Void type, + * the Any type, or a union type containing the Void or Any type as a constituent + * must have at least one return statement somewhere in its body. + * An exception to this rule is if the function implementation consists of a single 'throw' statement. + * + * @param returnType - return type of the function, can be undefined if return type is not explicitly specified + */ + function checkAllCodePathsInNonVoidFunctionReturnOrThrow(func: FunctionLikeDeclaration | MethodSignature, returnType: Type | undefined) { + addLazyDiagnostic(checkAllCodePathsInNonVoidFunctionReturnOrThrowDiagnostics); + return; + + function checkAllCodePathsInNonVoidFunctionReturnOrThrowDiagnostics(): void { + const functionFlags = getFunctionFlags(func); + const type = returnType && unwrapReturnType(returnType, functionFlags); + + // Functions with an explicitly specified return type that includes `void` or is exactly `any` or `undefined` don't + // need any return statements. + if (type && (maybeTypeOfKind(type, TypeFlags.Void) || type.flags & (TypeFlags.Any | TypeFlags.Undefined))) { + return; + } + + // If all we have is a function signature, or an arrow function with an expression body, then there is nothing to check. + // also if HasImplicitReturn flag is not set this means that all codepaths in function body end with return or throw + if (func.kind === SyntaxKind.MethodSignature || nodeIsMissing(func.body) || func.body!.kind !== SyntaxKind.Block || !functionHasImplicitReturn(func)) { + return; + } + + const hasExplicitReturn = func.flags & NodeFlags.HasExplicitReturn; + const errorNode = getEffectiveReturnTypeNode(func) || func; + + if (type && type.flags & TypeFlags.Never) { + error(errorNode, Diagnostics.A_function_returning_never_cannot_have_a_reachable_end_point); + } + else if (type && !hasExplicitReturn) { + // minimal check: function has syntactic return type annotation and no explicit return statements in the body + // this function does not conform to the specification. + error(errorNode, Diagnostics.A_function_whose_declared_type_is_neither_undefined_void_nor_any_must_return_a_value); + } + else if (type && strictNullChecks && !isTypeAssignableTo(undefinedType, type)) { + error(errorNode, Diagnostics.Function_lacks_ending_return_statement_and_return_type_does_not_include_undefined); + } + else if (compilerOptions.noImplicitReturns) { + if (!type) { + // If return type annotation is omitted check if function has any explicit return statements. + // If it does not have any - its inferred return type is void - don't do any checks. + // Otherwise get inferred return type from function body and report error only if it is not void / anytype + if (!hasExplicitReturn) { + return; + } + const inferredReturnType = getReturnTypeOfSignature(getSignatureFromDeclaration(func)); + if (isUnwrappedReturnTypeUndefinedVoidOrAny(func, inferredReturnType)) { + return; + } + } + error(errorNode, Diagnostics.Not_all_code_paths_return_a_value); + } + } + } + + function checkFunctionExpressionOrObjectLiteralMethod(node: FunctionExpression | ArrowFunction | MethodDeclaration, checkMode?: CheckMode): Type { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + checkNodeDeferred(node); + + if (isFunctionExpression(node)) { + checkCollisionsForDeclarationName(node, node.name); + } + + // The identityMapper object is used to indicate that function expressions are wildcards + if (checkMode && checkMode & CheckMode.SkipContextSensitive && isContextSensitive(node)) { + // Skip parameters, return signature with return type that retains noncontextual parts so inferences can still be drawn in an early stage + if (!getEffectiveReturnTypeNode(node) && !hasContextSensitiveParameters(node)) { + // Return plain anyFunctionType if there is no possibility we'll make inferences from the return type + const contextualSignature = getContextualSignature(node); + if (contextualSignature && couldContainTypeVariables(getReturnTypeOfSignature(contextualSignature))) { + const links = getNodeLinks(node); + if (links.contextFreeType) { + return links.contextFreeType; + } + const returnType = getReturnTypeFromBody(node, checkMode); + const returnOnlySignature = createSignature(/*declaration*/ undefined, /*typeParameters*/ undefined, /*thisParameter*/ undefined, emptyArray, returnType, /*resolvedTypePredicate*/ undefined, 0, SignatureFlags.IsNonInferrable); + const returnOnlyType = createAnonymousType(node.symbol, emptySymbols, [returnOnlySignature], emptyArray, emptyArray); + returnOnlyType.objectFlags |= ObjectFlags.NonInferrableType; + return links.contextFreeType = returnOnlyType; + } + } + return anyFunctionType; + } + + // Grammar checking + const hasGrammarError = checkGrammarFunctionLikeDeclaration(node); + if (!hasGrammarError && node.kind === SyntaxKind.FunctionExpression) { + checkGrammarForGenerator(node); + } + + contextuallyCheckFunctionExpressionOrObjectLiteralMethod(node, checkMode); + + return getTypeOfSymbol(getSymbolOfDeclaration(node)); + } + + function contextuallyCheckFunctionExpressionOrObjectLiteralMethod(node: FunctionExpression | ArrowFunction | MethodDeclaration, checkMode?: CheckMode) { + const links = getNodeLinks(node); + // Check if function expression is contextually typed and assign parameter types if so. + if (!(links.flags & NodeCheckFlags.ContextChecked)) { + const contextualSignature = getContextualSignature(node); + // If a type check is started at a function expression that is an argument of a function call, obtaining the + // contextual type may recursively get back to here during overload resolution of the call. If so, we will have + // already assigned contextual types. + if (!(links.flags & NodeCheckFlags.ContextChecked)) { + links.flags |= NodeCheckFlags.ContextChecked; + const signature = firstOrUndefined(getSignaturesOfType(getTypeOfSymbol(getSymbolOfDeclaration(node)), SignatureKind.Call)); + if (!signature) { + return; + } + if (isContextSensitive(node)) { + if (contextualSignature) { + const inferenceContext = getInferenceContext(node); + let instantiatedContextualSignature: Signature | undefined; + if (checkMode && checkMode & CheckMode.Inferential) { + inferFromAnnotatedParameters(signature, contextualSignature, inferenceContext!); + const restType = getEffectiveRestType(contextualSignature); + if (restType && restType.flags & TypeFlags.TypeParameter) { + instantiatedContextualSignature = instantiateSignature(contextualSignature, inferenceContext!.nonFixingMapper); + } + } + instantiatedContextualSignature ||= inferenceContext ? + instantiateSignature(contextualSignature, inferenceContext.mapper) : contextualSignature; + assignContextualParameterTypes(signature, instantiatedContextualSignature); + } + else { + // Force resolution of all parameter types such that the absence of a contextual type is consistently reflected. + assignNonContextualParameterTypes(signature); + } + } + else if (contextualSignature && !node.typeParameters && contextualSignature.parameters.length > node.parameters.length) { + const inferenceContext = getInferenceContext(node); + if (checkMode && checkMode & CheckMode.Inferential) { + inferFromAnnotatedParameters(signature, contextualSignature, inferenceContext!); + } + } + if (contextualSignature && !getReturnTypeFromAnnotation(node) && !signature.resolvedReturnType) { + const returnType = getReturnTypeFromBody(node, checkMode); + if (!signature.resolvedReturnType) { + signature.resolvedReturnType = returnType; + } + } + checkSignatureDeclaration(node); + } + } + } + + function checkFunctionExpressionOrObjectLiteralMethodDeferred(node: ArrowFunction | FunctionExpression | MethodDeclaration) { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + + const functionFlags = getFunctionFlags(node); + const returnType = getReturnTypeFromAnnotation(node); + checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType); + + if (node.body) { + if (!getEffectiveReturnTypeNode(node)) { + // There are some checks that are only performed in getReturnTypeFromBody, that may produce errors + // we need. An example is the noImplicitAny errors resulting from widening the return expression + // of a function. Because checking of function expression bodies is deferred, there was never an + // appropriate time to do this during the main walk of the file (see the comment at the top of + // checkFunctionExpressionBodies). So it must be done now. + getReturnTypeOfSignature(getSignatureFromDeclaration(node)); + } + + if (node.body.kind === SyntaxKind.Block) { + checkSourceElement(node.body); + } + else { + // From within an async function you can return either a non-promise value or a promise. Any + // Promise/A+ compatible implementation will always assimilate any foreign promise, so we + // should not be checking assignability of a promise to the return type. Instead, we need to + // check assignability of the awaited type of the expression body against the promised type of + // its return type annotation. + const exprType = checkExpression(node.body); + const returnOrPromisedType = returnType && unwrapReturnType(returnType, functionFlags); + if (returnOrPromisedType) { + const effectiveCheckNode = getEffectiveCheckNode(node.body); + if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async) { // Async function + const awaitedType = checkAwaitedType(exprType, /*withAlias*/ false, effectiveCheckNode, Diagnostics.The_return_type_of_an_async_function_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); + checkTypeAssignableToAndOptionallyElaborate(awaitedType, returnOrPromisedType, effectiveCheckNode, effectiveCheckNode); + } + else { // Normal function + checkTypeAssignableToAndOptionallyElaborate(exprType, returnOrPromisedType, effectiveCheckNode, effectiveCheckNode); + } + } + } + } + } + + function checkArithmeticOperandType(operand: Node, type: Type, diagnostic: DiagnosticMessage, isAwaitValid = false): boolean { + if (!isTypeAssignableTo(type, numberOrBigIntType)) { + const awaitedType = isAwaitValid && getAwaitedTypeOfPromise(type); + errorAndMaybeSuggestAwait( + operand, + !!awaitedType && isTypeAssignableTo(awaitedType, numberOrBigIntType), + diagnostic, + ); + return false; + } + return true; + } + + function isReadonlyAssignmentDeclaration(d: Declaration) { + if (!isCallExpression(d)) { + return false; + } + if (!isBindableObjectDefinePropertyCall(d)) { + return false; + } + const objectLitType = checkExpressionCached(d.arguments[2]); + const valueType = getTypeOfPropertyOfType(objectLitType, "value" as __String); + if (valueType) { + const writableProp = getPropertyOfType(objectLitType, "writable" as __String); + const writableType = writableProp && getTypeOfSymbol(writableProp); + if (!writableType || writableType === falseType || writableType === regularFalseType) { + return true; + } + // We include this definition whereupon we walk back and check the type at the declaration because + // The usual definition of `Object.defineProperty` will _not_ cause literal types to be preserved in the + // argument types, should the type be contextualized by the call itself. + if (writableProp && writableProp.valueDeclaration && isPropertyAssignment(writableProp.valueDeclaration)) { + const initializer = writableProp.valueDeclaration.initializer; + const rawOriginalType = checkExpression(initializer); + if (rawOriginalType === falseType || rawOriginalType === regularFalseType) { + return true; + } + } + return false; + } + const setProp = getPropertyOfType(objectLitType, "set" as __String); + return !setProp; + } + + function isReadonlySymbol(symbol: Symbol): boolean { + // The following symbols are considered read-only: + // Properties with a 'readonly' modifier + // Variables declared with 'const' + // Get accessors without matching set accessors + // Enum members + // Object.defineProperty assignments with writable false or no setter + // Unions and intersections of the above (unions and intersections eagerly set isReadonly on creation) + return !!(getCheckFlags(symbol) & CheckFlags.Readonly || + symbol.flags & SymbolFlags.Property && getDeclarationModifierFlagsFromSymbol(symbol) & ModifierFlags.Readonly || + symbol.flags & SymbolFlags.Variable && getDeclarationNodeFlagsFromSymbol(symbol) & NodeFlags.Constant || + symbol.flags & SymbolFlags.Accessor && !(symbol.flags & SymbolFlags.SetAccessor) || + symbol.flags & SymbolFlags.EnumMember || + some(symbol.declarations, isReadonlyAssignmentDeclaration)); + } + + function isAssignmentToReadonlyEntity(expr: Expression, symbol: Symbol, assignmentKind: AssignmentKind) { + if (assignmentKind === AssignmentKind.None) { + // no assigment means it doesn't matter whether the entity is readonly + return false; + } + if (isReadonlySymbol(symbol)) { + // Allow assignments to readonly properties within constructors of the same class declaration. + if ( + symbol.flags & SymbolFlags.Property && + isAccessExpression(expr) && + expr.expression.kind === SyntaxKind.ThisKeyword + ) { + // Look for if this is the constructor for the class that `symbol` is a property of. + const ctor = getContainingFunction(expr); + if (!(ctor && (ctor.kind === SyntaxKind.Constructor || isJSConstructor(ctor)))) { + return true; + } + if (symbol.valueDeclaration) { + const isAssignmentDeclaration = isBinaryExpression(symbol.valueDeclaration); + const isLocalPropertyDeclaration = ctor.parent === symbol.valueDeclaration.parent; + const isLocalParameterProperty = ctor === symbol.valueDeclaration.parent; + const isLocalThisPropertyAssignment = isAssignmentDeclaration && symbol.parent?.valueDeclaration === ctor.parent; + const isLocalThisPropertyAssignmentConstructorFunction = isAssignmentDeclaration && symbol.parent?.valueDeclaration === ctor; + const isWriteableSymbol = isLocalPropertyDeclaration + || isLocalParameterProperty + || isLocalThisPropertyAssignment + || isLocalThisPropertyAssignmentConstructorFunction; + return !isWriteableSymbol; + } + } + return true; + } + if (isAccessExpression(expr)) { + // references through namespace import should be readonly + const node = skipParentheses(expr.expression); + if (node.kind === SyntaxKind.Identifier) { + const symbol = getNodeLinks(node).resolvedSymbol!; + if (symbol.flags & SymbolFlags.Alias) { + const declaration = getDeclarationOfAliasSymbol(symbol); + return !!declaration && declaration.kind === SyntaxKind.NamespaceImport; + } + } + } + return false; + } + + function checkReferenceExpression(expr: Expression, invalidReferenceMessage: DiagnosticMessage, invalidOptionalChainMessage: DiagnosticMessage): boolean { + // References are combinations of identifiers, parentheses, and property accesses. + const node = skipOuterExpressions(expr, OuterExpressionKinds.Assertions | OuterExpressionKinds.Parentheses); + if (node.kind !== SyntaxKind.Identifier && !isAccessExpression(node)) { + error(expr, invalidReferenceMessage); + return false; + } + if (node.flags & NodeFlags.OptionalChain) { + error(expr, invalidOptionalChainMessage); + return false; + } + return true; + } + + function checkDeleteExpression(node: DeleteExpression): Type { + checkExpression(node.expression); + const expr = skipParentheses(node.expression); + if (!isAccessExpression(expr)) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_must_be_a_property_reference); + return booleanType; + } + if (isPropertyAccessExpression(expr) && isPrivateIdentifier(expr.name)) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_cannot_be_a_private_identifier); + } + const links = getNodeLinks(expr); + const symbol = getExportSymbolOfValueSymbolIfExported(links.resolvedSymbol); + if (symbol) { + if (isReadonlySymbol(symbol)) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_cannot_be_a_read_only_property); + } + else { + checkDeleteExpressionMustBeOptional(expr, symbol); + } + } + return booleanType; + } + + function checkDeleteExpressionMustBeOptional(expr: AccessExpression, symbol: Symbol) { + const type = getTypeOfSymbol(symbol); + if ( + strictNullChecks && + !(type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Never)) && + !(exactOptionalPropertyTypes ? symbol.flags & SymbolFlags.Optional : hasTypeFacts(type, TypeFacts.IsUndefined)) + ) { + error(expr, Diagnostics.The_operand_of_a_delete_operator_must_be_optional); + } + } + + function checkTypeOfExpression(node: TypeOfExpression): Type { + checkExpression(node.expression); + return typeofType; + } + + function checkVoidExpression(node: VoidExpression): Type { + checkNodeDeferred(node); + return undefinedWideningType; + } + + function checkAwaitGrammar(node: AwaitExpression | VariableDeclarationList): boolean { + // Grammar checking + let hasError = false; + const container = getContainingFunctionOrClassStaticBlock(node); + if (container && isClassStaticBlockDeclaration(container)) { + // NOTE: We report this regardless as to whether there are parse diagnostics. + const message = isAwaitExpression(node) ? Diagnostics.await_expression_cannot_be_used_inside_a_class_static_block : + Diagnostics.await_using_statements_cannot_be_used_inside_a_class_static_block; + error(node, message); + hasError = true; + } + else if (!(node.flags & NodeFlags.AwaitContext)) { + if (isInTopLevelContext(node)) { + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + let span: TextSpan | undefined; + if (!isEffectiveExternalModule(sourceFile, compilerOptions)) { + span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); + const message = isAwaitExpression(node) ? Diagnostics.await_expressions_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module : + Diagnostics.await_using_statements_are_only_allowed_at_the_top_level_of_a_file_when_that_file_is_a_module_but_this_file_has_no_imports_or_exports_Consider_adding_an_empty_export_to_make_this_file_a_module; + const diagnostic = createFileDiagnostic(sourceFile, span.start, span.length, message); + diagnostics.add(diagnostic); + hasError = true; + } + switch (moduleKind) { + case ModuleKind.Node16: + case ModuleKind.NodeNext: + if (sourceFile.impliedNodeFormat === ModuleKind.CommonJS) { + span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); + diagnostics.add( + createFileDiagnostic(sourceFile, span.start, span.length, Diagnostics.The_current_file_is_a_CommonJS_module_and_cannot_use_await_at_the_top_level), + ); + hasError = true; + break; + } + // fallthrough + case ModuleKind.ES2022: + case ModuleKind.ESNext: + case ModuleKind.Preserve: + case ModuleKind.System: + if (languageVersion >= ScriptTarget.ES2017) { + break; + } + // fallthrough + default: + span ??= getSpanOfTokenAtPosition(sourceFile, node.pos); + const message = isAwaitExpression(node) ? Diagnostics.Top_level_await_expressions_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_nodenext_or_preserve_and_the_target_option_is_set_to_es2017_or_higher : + Diagnostics.Top_level_await_using_statements_are_only_allowed_when_the_module_option_is_set_to_es2022_esnext_system_node16_nodenext_or_preserve_and_the_target_option_is_set_to_es2017_or_higher; + diagnostics.add(createFileDiagnostic(sourceFile, span.start, span.length, message)); + hasError = true; + break; + } + } + } + else { + // use of 'await' in non-async function + const sourceFile = getSourceFileOfNode(node); + if (!hasParseDiagnostics(sourceFile)) { + const span = getSpanOfTokenAtPosition(sourceFile, node.pos); + const message = isAwaitExpression(node) ? Diagnostics.await_expressions_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules : + Diagnostics.await_using_statements_are_only_allowed_within_async_functions_and_at_the_top_levels_of_modules; + const diagnostic = createFileDiagnostic(sourceFile, span.start, span.length, message); + if (container && container.kind !== SyntaxKind.Constructor && (getFunctionFlags(container) & FunctionFlags.Async) === 0) { + const relatedInfo = createDiagnosticForNode(container, Diagnostics.Did_you_mean_to_mark_this_function_as_async); + addRelatedInfo(diagnostic, relatedInfo); + } + diagnostics.add(diagnostic); + hasError = true; + } + } + } + + if (isAwaitExpression(node) && isInParameterInitializerBeforeContainingFunction(node)) { + // NOTE: We report this regardless as to whether there are parse diagnostics. + error(node, Diagnostics.await_expressions_cannot_be_used_in_a_parameter_initializer); + hasError = true; + } + + return hasError; + } + + function checkAwaitExpression(node: AwaitExpression): Type { + addLazyDiagnostic(() => checkAwaitGrammar(node)); + + const operandType = checkExpression(node.expression); + const awaitedType = checkAwaitedType(operandType, /*withAlias*/ true, node, Diagnostics.Type_of_await_operand_must_either_be_a_valid_promise_or_must_not_contain_a_callable_then_member); + if (awaitedType === operandType && !isErrorType(awaitedType) && !(operandType.flags & TypeFlags.AnyOrUnknown)) { + addErrorOrSuggestion(/*isError*/ false, createDiagnosticForNode(node, Diagnostics.await_has_no_effect_on_the_type_of_this_expression)); + } + return awaitedType; + } + + function checkPrefixUnaryExpression(node: PrefixUnaryExpression): Type { + const operandType = checkExpression(node.operand); + if (operandType === silentNeverType) { + return silentNeverType; + } + switch (node.operand.kind) { + case SyntaxKind.NumericLiteral: + switch (node.operator) { + case SyntaxKind.MinusToken: + return getFreshTypeOfLiteralType(getNumberLiteralType(-(node.operand as NumericLiteral).text)); + case SyntaxKind.PlusToken: + return getFreshTypeOfLiteralType(getNumberLiteralType(+(node.operand as NumericLiteral).text)); + } + break; + case SyntaxKind.BigIntLiteral: + if (node.operator === SyntaxKind.MinusToken) { + return getFreshTypeOfLiteralType(getBigIntLiteralType({ + negative: true, + base10Value: parsePseudoBigInt((node.operand as BigIntLiteral).text), + })); + } + } + switch (node.operator) { + case SyntaxKind.PlusToken: + case SyntaxKind.MinusToken: + case SyntaxKind.TildeToken: + checkNonNullType(operandType, node.operand); + if (maybeTypeOfKindConsideringBaseConstraint(operandType, TypeFlags.ESSymbolLike)) { + error(node.operand, Diagnostics.The_0_operator_cannot_be_applied_to_type_symbol, tokenToString(node.operator)); + } + if (node.operator === SyntaxKind.PlusToken) { + if (maybeTypeOfKindConsideringBaseConstraint(operandType, TypeFlags.BigIntLike)) { + error(node.operand, Diagnostics.Operator_0_cannot_be_applied_to_type_1, tokenToString(node.operator), typeToString(getBaseTypeOfLiteralType(operandType))); + } + return numberType; + } + return getUnaryResultType(operandType); + case SyntaxKind.ExclamationToken: + checkTruthinessOfType(operandType, node.operand); + const facts = getTypeFacts(operandType, TypeFacts.Truthy | TypeFacts.Falsy); + return facts === TypeFacts.Truthy ? falseType : + facts === TypeFacts.Falsy ? trueType : + booleanType; + case SyntaxKind.PlusPlusToken: + case SyntaxKind.MinusMinusToken: + const ok = checkArithmeticOperandType(node.operand, checkNonNullType(operandType, node.operand), Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type); + if (ok) { + // run check only if former checks succeeded to avoid reporting cascading errors + checkReferenceExpression( + node.operand, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access, + ); + } + return getUnaryResultType(operandType); + } + return errorType; + } + + function checkPostfixUnaryExpression(node: PostfixUnaryExpression): Type { + const operandType = checkExpression(node.operand); + if (operandType === silentNeverType) { + return silentNeverType; + } + const ok = checkArithmeticOperandType( + node.operand, + checkNonNullType(operandType, node.operand), + Diagnostics.An_arithmetic_operand_must_be_of_type_any_number_bigint_or_an_enum_type, + ); + if (ok) { + // run check only if former checks succeeded to avoid reporting cascading errors + checkReferenceExpression( + node.operand, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_or_a_property_access, + Diagnostics.The_operand_of_an_increment_or_decrement_operator_may_not_be_an_optional_property_access, + ); + } + return getUnaryResultType(operandType); + } + + function getUnaryResultType(operandType: Type): Type { + if (maybeTypeOfKind(operandType, TypeFlags.BigIntLike)) { + return isTypeAssignableToKind(operandType, TypeFlags.AnyOrUnknown) || maybeTypeOfKind(operandType, TypeFlags.NumberLike) + ? numberOrBigIntType + : bigintType; + } + // If it's not a bigint type, implicit coercion will result in a number + return numberType; + } + + function maybeTypeOfKindConsideringBaseConstraint(type: Type, kind: TypeFlags): boolean { + if (maybeTypeOfKind(type, kind)) { + return true; + } + + const baseConstraint = getBaseConstraintOrType(type); + return !!baseConstraint && maybeTypeOfKind(baseConstraint, kind); + } + + // Return true if type might be of the given kind. A union or intersection type might be of a given + // kind if at least one constituent type is of the given kind. + function maybeTypeOfKind(type: Type, kind: TypeFlags): boolean { + if (type.flags & kind) { + return true; + } + if (type.flags & TypeFlags.UnionOrIntersection) { + const types = (type as UnionOrIntersectionType).types; + for (const t of types) { + if (maybeTypeOfKind(t, kind)) { + return true; + } + } + } + return false; + } + + function isTypeAssignableToKind(source: Type, kind: TypeFlags, strict?: boolean): boolean { + if (source.flags & kind) { + return true; + } + if (strict && source.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Void | TypeFlags.Undefined | TypeFlags.Null)) { + return false; + } + return !!(kind & TypeFlags.NumberLike) && isTypeAssignableTo(source, numberType) || + !!(kind & TypeFlags.BigIntLike) && isTypeAssignableTo(source, bigintType) || + !!(kind & TypeFlags.StringLike) && isTypeAssignableTo(source, stringType) || + !!(kind & TypeFlags.BooleanLike) && isTypeAssignableTo(source, booleanType) || + !!(kind & TypeFlags.Void) && isTypeAssignableTo(source, voidType) || + !!(kind & TypeFlags.Never) && isTypeAssignableTo(source, neverType) || + !!(kind & TypeFlags.Null) && isTypeAssignableTo(source, nullType) || + !!(kind & TypeFlags.Undefined) && isTypeAssignableTo(source, undefinedType) || + !!(kind & TypeFlags.ESSymbol) && isTypeAssignableTo(source, esSymbolType) || + !!(kind & TypeFlags.NonPrimitive) && isTypeAssignableTo(source, nonPrimitiveType); + } + + function allTypesAssignableToKind(source: Type, kind: TypeFlags, strict?: boolean): boolean { + return source.flags & TypeFlags.Union ? + every((source as UnionType).types, subType => allTypesAssignableToKind(subType, kind, strict)) : + isTypeAssignableToKind(source, kind, strict); + } + + function isConstEnumObjectType(type: Type): boolean { + return !!(getObjectFlags(type) & ObjectFlags.Anonymous) && !!type.symbol && isConstEnumSymbol(type.symbol); + } + + function isConstEnumSymbol(symbol: Symbol): boolean { + return (symbol.flags & SymbolFlags.ConstEnum) !== 0; + } + + /** + * Get the type of the `[Symbol.hasInstance]` method of an object type. + */ + function getSymbolHasInstanceMethodOfObjectType(type: Type) { + const hasInstancePropertyName = getPropertyNameForKnownSymbolName("hasInstance"); + if (allTypesAssignableToKind(type, TypeFlags.NonPrimitive)) { + const hasInstanceProperty = getPropertyOfType(type, hasInstancePropertyName); + if (hasInstanceProperty) { + const hasInstancePropertyType = getTypeOfSymbol(hasInstanceProperty); + if (hasInstancePropertyType && getSignaturesOfType(hasInstancePropertyType, SignatureKind.Call).length !== 0) { + return hasInstancePropertyType; + } + } + } + } + + function checkInstanceOfExpression(left: Expression, right: Expression, leftType: Type, rightType: Type, checkMode?: CheckMode): Type { + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + + // TypeScript 1.0 spec (April 2014): 4.15.4 + // The instanceof operator requires the left operand to be of type Any, an object type, or a type parameter type, + // and the right operand to be of type Any, a subtype of the 'Function' interface type, or have a call or construct signature. + // The result is always of the Boolean primitive type. + // NOTE: do not raise error if leftType is unknown as related error was already reported + if ( + !isTypeAny(leftType) && + allTypesAssignableToKind(leftType, TypeFlags.Primitive) + ) { + error(left, Diagnostics.The_left_hand_side_of_an_instanceof_expression_must_be_of_type_any_an_object_type_or_a_type_parameter); + } + + Debug.assert(isInstanceOfExpression(left.parent)); + const signature = getResolvedSignature(left.parent, /*candidatesOutArray*/ undefined, checkMode); + if (signature === resolvingSignature) { + // CheckMode.SkipGenericFunctions is enabled and this is a call to a generic function that + // returns a function type. We defer checking and return silentNeverType. + return silentNeverType; + } + + // If rightType has a `[Symbol.hasInstance]` method that is not `(value: unknown) => boolean`, we + // must check the expression as if it were a call to `right[Symbol.hasInstance](left)`. The call to + // `getResolvedSignature`, below, will check that leftType is assignable to the type of the first + // parameter. + const returnType = getReturnTypeOfSignature(signature); + + // We also verify that the return type of the `[Symbol.hasInstance]` method is assignable to + // `boolean`. According to the spec, the runtime will actually perform `ToBoolean` on the result, + // but this is more type-safe. + checkTypeAssignableTo(returnType, booleanType, right, Diagnostics.An_object_s_Symbol_hasInstance_method_must_return_a_boolean_value_for_it_to_be_used_on_the_right_hand_side_of_an_instanceof_expression); + + return booleanType; + } + + function hasEmptyObjectIntersection(type: Type): boolean { + return someType(type, t => t === unknownEmptyObjectType || !!(t.flags & TypeFlags.Intersection) && isEmptyAnonymousObjectType(getBaseConstraintOrType(t))); + } + + function checkInExpression(left: Expression, right: Expression, leftType: Type, rightType: Type): Type { + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + if (isPrivateIdentifier(left)) { + if ( + languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators || + !useDefineForClassFields + ) { + checkExternalEmitHelpers(left, ExternalEmitHelpers.ClassPrivateFieldIn); + } + // Unlike in 'checkPrivateIdentifierExpression' we now have access to the RHS type + // which provides us with the opportunity to emit more detailed errors + if (!getNodeLinks(left).resolvedSymbol && getContainingClass(left)) { + const isUncheckedJS = isUncheckedJSSuggestion(left, rightType.symbol, /*excludeClasses*/ true); + reportNonexistentProperty(left, rightType, isUncheckedJS); + } + } + else { + // The type of the lef operand must be assignable to string, number, or symbol. + checkTypeAssignableTo(checkNonNullType(leftType, left), stringNumberSymbolType, left); + } + // The type of the right operand must be assignable to 'object'. + if (checkTypeAssignableTo(checkNonNullType(rightType, right), nonPrimitiveType, right)) { + // The {} type is assignable to the object type, yet {} might represent a primitive type. Here we + // detect and error on {} that results from narrowing the unknown type, as well as intersections + // that include {} (we know that the other types in such intersections are assignable to object + // since we already checked for that). + if (hasEmptyObjectIntersection(rightType)) { + error(right, Diagnostics.Type_0_may_represent_a_primitive_value_which_is_not_permitted_as_the_right_operand_of_the_in_operator, typeToString(rightType)); + } + } + // The result is always of the Boolean primitive type. + return booleanType; + } + + function checkObjectLiteralAssignment(node: ObjectLiteralExpression, sourceType: Type, rightIsThis?: boolean): Type { + const properties = node.properties; + if (strictNullChecks && properties.length === 0) { + return checkNonNullType(sourceType, node); + } + for (let i = 0; i < properties.length; i++) { + checkObjectLiteralDestructuringPropertyAssignment(node, sourceType, i, properties, rightIsThis); + } + return sourceType; + } + + /** Note: If property cannot be a SpreadAssignment, then allProperties does not need to be provided */ + function checkObjectLiteralDestructuringPropertyAssignment(node: ObjectLiteralExpression, objectLiteralType: Type, propertyIndex: number, allProperties?: NodeArray, rightIsThis = false) { + const properties = node.properties; + const property = properties[propertyIndex]; + if (property.kind === SyntaxKind.PropertyAssignment || property.kind === SyntaxKind.ShorthandPropertyAssignment) { + const name = property.name; + const exprType = getLiteralTypeFromPropertyName(name); + if (isTypeUsableAsPropertyName(exprType)) { + const text = getPropertyNameFromType(exprType); + const prop = getPropertyOfType(objectLiteralType, text); + if (prop) { + markPropertyAsReferenced(prop, property, rightIsThis); + checkPropertyAccessibility(property, /*isSuper*/ false, /*writing*/ true, objectLiteralType, prop); + } + } + const elementType = getIndexedAccessType(objectLiteralType, exprType, AccessFlags.ExpressionPosition, name); + const type = getFlowTypeOfDestructuring(property, elementType); + return checkDestructuringAssignment(property.kind === SyntaxKind.ShorthandPropertyAssignment ? property : property.initializer, type); + } + else if (property.kind === SyntaxKind.SpreadAssignment) { + if (propertyIndex < properties.length - 1) { + error(property, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); + } + else { + if (languageVersion < LanguageFeatureMinimumTarget.ObjectSpreadRest) { + checkExternalEmitHelpers(property, ExternalEmitHelpers.Rest); + } + const nonRestNames: PropertyName[] = []; + if (allProperties) { + for (const otherProperty of allProperties) { + if (!isSpreadAssignment(otherProperty)) { + nonRestNames.push(otherProperty.name); + } + } + } + const type = getRestType(objectLiteralType, nonRestNames, objectLiteralType.symbol); + checkGrammarForDisallowedTrailingComma(allProperties, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + return checkDestructuringAssignment(property.expression, type); + } + } + else { + error(property, Diagnostics.Property_assignment_expected); + } + } + + function checkArrayLiteralAssignment(node: ArrayLiteralExpression, sourceType: Type, checkMode?: CheckMode): Type { + const elements = node.elements; + if (languageVersion < LanguageFeatureMinimumTarget.DestructuringAssignment && compilerOptions.downlevelIteration) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Read); + } + // This elementType will be used if the specific property corresponding to this index is not + // present (aka the tuple element property). This call also checks that the parentType is in + // fact an iterable or array (depending on target language). + const possiblyOutOfBoundsType = checkIteratedTypeOrElementType(IterationUse.Destructuring | IterationUse.PossiblyOutOfBounds, sourceType, undefinedType, node) || errorType; + let inBoundsType: Type | undefined = compilerOptions.noUncheckedIndexedAccess ? undefined : possiblyOutOfBoundsType; + for (let i = 0; i < elements.length; i++) { + let type = possiblyOutOfBoundsType; + if (node.elements[i].kind === SyntaxKind.SpreadElement) { + type = inBoundsType = inBoundsType ?? (checkIteratedTypeOrElementType(IterationUse.Destructuring, sourceType, undefinedType, node) || errorType); + } + checkArrayLiteralDestructuringElementAssignment(node, sourceType, i, type, checkMode); + } + return sourceType; + } + + function checkArrayLiteralDestructuringElementAssignment(node: ArrayLiteralExpression, sourceType: Type, elementIndex: number, elementType: Type, checkMode?: CheckMode) { + const elements = node.elements; + const element = elements[elementIndex]; + if (element.kind !== SyntaxKind.OmittedExpression) { + if (element.kind !== SyntaxKind.SpreadElement) { + const indexType = getNumberLiteralType(elementIndex); + if (isArrayLikeType(sourceType)) { + // We create a synthetic expression so that getIndexedAccessType doesn't get confused + // when the element is a SyntaxKind.ElementAccessExpression. + const accessFlags = AccessFlags.ExpressionPosition | (hasDefaultValue(element) ? AccessFlags.NoTupleBoundsCheck : 0); + const elementType = getIndexedAccessTypeOrUndefined(sourceType, indexType, accessFlags, createSyntheticExpression(element, indexType)) || errorType; + const assignedType = hasDefaultValue(element) ? getTypeWithFacts(elementType, TypeFacts.NEUndefined) : elementType; + const type = getFlowTypeOfDestructuring(element, assignedType); + return checkDestructuringAssignment(element, type, checkMode); + } + return checkDestructuringAssignment(element, elementType, checkMode); + } + if (elementIndex < elements.length - 1) { + error(element, Diagnostics.A_rest_element_must_be_last_in_a_destructuring_pattern); + } + else { + const restExpression = (element as SpreadElement).expression; + if (restExpression.kind === SyntaxKind.BinaryExpression && (restExpression as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) { + error((restExpression as BinaryExpression).operatorToken, Diagnostics.A_rest_element_cannot_have_an_initializer); + } + else { + checkGrammarForDisallowedTrailingComma(node.elements, Diagnostics.A_rest_parameter_or_binding_pattern_may_not_have_a_trailing_comma); + const type = everyType(sourceType, isTupleType) ? + mapType(sourceType, t => sliceTupleType(t as TupleTypeReference, elementIndex)) : + createArrayType(elementType); + return checkDestructuringAssignment(restExpression, type, checkMode); + } + } + } + return undefined; + } + + function checkDestructuringAssignment(exprOrAssignment: Expression | ShorthandPropertyAssignment, sourceType: Type, checkMode?: CheckMode, rightIsThis?: boolean): Type { + let target: Expression; + if (exprOrAssignment.kind === SyntaxKind.ShorthandPropertyAssignment) { + const prop = exprOrAssignment as ShorthandPropertyAssignment; + if (prop.objectAssignmentInitializer) { + // In strict null checking mode, if a default value of a non-undefined type is specified, remove + // undefined from the final type. + if ( + strictNullChecks && + !(hasTypeFacts(checkExpression(prop.objectAssignmentInitializer), TypeFacts.IsUndefined)) + ) { + sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined); + } + checkBinaryLikeExpression(prop.name, prop.equalsToken!, prop.objectAssignmentInitializer, checkMode); + } + target = (exprOrAssignment as ShorthandPropertyAssignment).name; + } + else { + target = exprOrAssignment; + } + + if (target.kind === SyntaxKind.BinaryExpression && (target as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken) { + checkBinaryExpression(target as BinaryExpression, checkMode); + target = (target as BinaryExpression).left; + // A default value is specified, so remove undefined from the final type. + if (strictNullChecks) { + sourceType = getTypeWithFacts(sourceType, TypeFacts.NEUndefined); + } + } + if (target.kind === SyntaxKind.ObjectLiteralExpression) { + return checkObjectLiteralAssignment(target as ObjectLiteralExpression, sourceType, rightIsThis); + } + if (target.kind === SyntaxKind.ArrayLiteralExpression) { + return checkArrayLiteralAssignment(target as ArrayLiteralExpression, sourceType, checkMode); + } + return checkReferenceAssignment(target, sourceType, checkMode); + } + + function checkReferenceAssignment(target: Expression, sourceType: Type, checkMode?: CheckMode): Type { + const targetType = checkExpression(target, checkMode); + const error = target.parent.kind === SyntaxKind.SpreadAssignment ? + Diagnostics.The_target_of_an_object_rest_assignment_must_be_a_variable_or_a_property_access : + Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access; + const optionalError = target.parent.kind === SyntaxKind.SpreadAssignment ? + Diagnostics.The_target_of_an_object_rest_assignment_may_not_be_an_optional_property_access : + Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access; + if (checkReferenceExpression(target, error, optionalError)) { + checkTypeAssignableToAndOptionallyElaborate(sourceType, targetType, target, target); + } + if (isPrivateIdentifierPropertyAccessExpression(target)) { + // NOTE: we do not limit this to LanguageFeatureTargets.PrivateNames as some other feature downleveling still requires this. + checkExternalEmitHelpers(target.parent, ExternalEmitHelpers.ClassPrivateFieldSet); + } + return sourceType; + } + + /** + * This is a *shallow* check: An expression is side-effect-free if the + * evaluation of the expression *itself* cannot produce side effects. + * For example, x++ / 3 is side-effect free because the / operator + * does not have side effects. + * The intent is to "smell test" an expression for correctness in positions where + * its value is discarded (e.g. the left side of the comma operator). + */ + function isSideEffectFree(node: Node): boolean { + node = skipParentheses(node); + switch (node.kind) { + case SyntaxKind.Identifier: + case SyntaxKind.StringLiteral: + case SyntaxKind.RegularExpressionLiteral: + case SyntaxKind.TaggedTemplateExpression: + case SyntaxKind.TemplateExpression: + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.NumericLiteral: + case SyntaxKind.BigIntLiteral: + case SyntaxKind.TrueKeyword: + case SyntaxKind.FalseKeyword: + case SyntaxKind.NullKeyword: + case SyntaxKind.UndefinedKeyword: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ClassExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.ArrayLiteralExpression: + case SyntaxKind.ObjectLiteralExpression: + case SyntaxKind.TypeOfExpression: + case SyntaxKind.NonNullExpression: + case SyntaxKind.JsxSelfClosingElement: + case SyntaxKind.JsxElement: + return true; + + case SyntaxKind.ConditionalExpression: + return isSideEffectFree((node as ConditionalExpression).whenTrue) && + isSideEffectFree((node as ConditionalExpression).whenFalse); + + case SyntaxKind.BinaryExpression: + if (isAssignmentOperator((node as BinaryExpression).operatorToken.kind)) { + return false; + } + return isSideEffectFree((node as BinaryExpression).left) && + isSideEffectFree((node as BinaryExpression).right); + + case SyntaxKind.PrefixUnaryExpression: + case SyntaxKind.PostfixUnaryExpression: + // Unary operators ~, !, +, and - have no side effects. + // The rest do. + switch ((node as PrefixUnaryExpression).operator) { + case SyntaxKind.ExclamationToken: + case SyntaxKind.PlusToken: + case SyntaxKind.MinusToken: + case SyntaxKind.TildeToken: + return true; + } + return false; + + // Some forms listed here for clarity + case SyntaxKind.VoidExpression: // Explicit opt-out + case SyntaxKind.TypeAssertionExpression: // Not SEF, but can produce useful type warnings + case SyntaxKind.AsExpression: // Not SEF, but can produce useful type warnings + default: + return false; + } + } + + function isTypeEqualityComparableTo(source: Type, target: Type) { + return (target.flags & TypeFlags.Nullable) !== 0 || isTypeComparableTo(source, target); + } + + function createCheckBinaryExpression() { + interface WorkArea { + readonly checkMode: CheckMode | undefined; + skip: boolean; + stackIndex: number; + /** + * Holds the types from the left-side of an expression from [0..stackIndex]. + * Holds the type of the result at stackIndex+1. This allows us to reuse existing stack entries + * and avoid storing an extra property on the object (i.e., `lastResult`). + */ + typeStack: (Type | undefined)[]; + } + + const trampoline = createBinaryExpressionTrampoline(onEnter, onLeft, onOperator, onRight, onExit, foldState); + + return (node: BinaryExpression, checkMode: CheckMode | undefined) => { + const result = trampoline(node, checkMode); + Debug.assertIsDefined(result); + return result; + }; + + function onEnter(node: BinaryExpression, state: WorkArea | undefined, checkMode: CheckMode | undefined) { + if (state) { + state.stackIndex++; + state.skip = false; + setLeftType(state, /*type*/ undefined); + setLastResult(state, /*type*/ undefined); + } + else { + state = { + checkMode, + skip: false, + stackIndex: 0, + typeStack: [undefined, undefined], + }; + } + + if (isInJSFile(node) && getAssignedExpandoInitializer(node)) { + state.skip = true; + setLastResult(state, checkExpression(node.right, checkMode)); + return state; + } + + checkGrammarNullishCoalesceWithLogicalExpression(node); + + const operator = node.operatorToken.kind; + if (operator === SyntaxKind.EqualsToken && (node.left.kind === SyntaxKind.ObjectLiteralExpression || node.left.kind === SyntaxKind.ArrayLiteralExpression)) { + state.skip = true; + setLastResult(state, checkDestructuringAssignment(node.left, checkExpression(node.right, checkMode), checkMode, node.right.kind === SyntaxKind.ThisKeyword)); + return state; + } + + return state; + } + + function onLeft(left: Expression, state: WorkArea, _node: BinaryExpression) { + if (!state.skip) { + return maybeCheckExpression(state, left); + } + } + + function onOperator(operatorToken: BinaryOperatorToken, state: WorkArea, node: BinaryExpression) { + if (!state.skip) { + const leftType = getLastResult(state); + Debug.assertIsDefined(leftType); + setLeftType(state, leftType); + setLastResult(state, /*type*/ undefined); + const operator = operatorToken.kind; + if (isLogicalOrCoalescingBinaryOperator(operator)) { + let parent = node.parent; + while (parent.kind === SyntaxKind.ParenthesizedExpression || isLogicalOrCoalescingBinaryExpression(parent)) { + parent = parent.parent; + } + if (operator === SyntaxKind.AmpersandAmpersandToken || isIfStatement(parent)) { + checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(node.left, leftType, isIfStatement(parent) ? parent.thenStatement : undefined); + } + checkTruthinessOfType(leftType, node.left); + } + } + } + + function onRight(right: Expression, state: WorkArea, _node: BinaryExpression) { + if (!state.skip) { + return maybeCheckExpression(state, right); + } + } + + function onExit(node: BinaryExpression, state: WorkArea): Type | undefined { + let result: Type | undefined; + if (state.skip) { + result = getLastResult(state); + } + else { + const leftType = getLeftType(state); + Debug.assertIsDefined(leftType); + + const rightType = getLastResult(state); + Debug.assertIsDefined(rightType); + + result = checkBinaryLikeExpressionWorker(node.left, node.operatorToken, node.right, leftType, rightType, state.checkMode, node); + } + + state.skip = false; + setLeftType(state, /*type*/ undefined); + setLastResult(state, /*type*/ undefined); + state.stackIndex--; + return result; + } + + function foldState(state: WorkArea, result: Type | undefined, _side: "left" | "right") { + setLastResult(state, result); + return state; + } + + function maybeCheckExpression(state: WorkArea, node: Expression): BinaryExpression | undefined { + if (isBinaryExpression(node)) { + return node; + } + setLastResult(state, checkExpression(node, state.checkMode)); + } + + function getLeftType(state: WorkArea) { + return state.typeStack[state.stackIndex]; + } + + function setLeftType(state: WorkArea, type: Type | undefined) { + state.typeStack[state.stackIndex] = type; + } + + function getLastResult(state: WorkArea) { + return state.typeStack[state.stackIndex + 1]; + } + + function setLastResult(state: WorkArea, type: Type | undefined) { + // To reduce overhead, reuse the next stack entry to store the + // last result. This avoids the overhead of an additional property + // on `WorkArea` and reuses empty stack entries as we walk back up + // the stack. + state.typeStack[state.stackIndex + 1] = type; + } + } + + function checkGrammarNullishCoalesceWithLogicalExpression(node: BinaryExpression) { + const { left, operatorToken, right } = node; + if (operatorToken.kind === SyntaxKind.QuestionQuestionToken) { + if (isBinaryExpression(left) && (left.operatorToken.kind === SyntaxKind.BarBarToken || left.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken)) { + grammarErrorOnNode(left, Diagnostics._0_and_1_operations_cannot_be_mixed_without_parentheses, tokenToString(left.operatorToken.kind), tokenToString(operatorToken.kind)); + } + if (isBinaryExpression(right) && (right.operatorToken.kind === SyntaxKind.BarBarToken || right.operatorToken.kind === SyntaxKind.AmpersandAmpersandToken)) { + grammarErrorOnNode(right, Diagnostics._0_and_1_operations_cannot_be_mixed_without_parentheses, tokenToString(right.operatorToken.kind), tokenToString(operatorToken.kind)); + } + } + } + + // Note that this and `checkBinaryExpression` above should behave mostly the same, except this elides some + // expression-wide checks and does not use a work stack to fold nested binary expressions into the same callstack frame + function checkBinaryLikeExpression(left: Expression, operatorToken: BinaryOperatorToken, right: Expression, checkMode?: CheckMode, errorNode?: Node): Type { + const operator = operatorToken.kind; + if (operator === SyntaxKind.EqualsToken && (left.kind === SyntaxKind.ObjectLiteralExpression || left.kind === SyntaxKind.ArrayLiteralExpression)) { + return checkDestructuringAssignment(left, checkExpression(right, checkMode), checkMode, right.kind === SyntaxKind.ThisKeyword); + } + let leftType: Type; + if (isLogicalOrCoalescingBinaryOperator(operator)) { + leftType = checkTruthinessExpression(left, checkMode); + } + else { + leftType = checkExpression(left, checkMode); + } + + const rightType = checkExpression(right, checkMode); + return checkBinaryLikeExpressionWorker(left, operatorToken, right, leftType, rightType, checkMode, errorNode); + } + + function checkBinaryLikeExpressionWorker( + left: Expression, + operatorToken: BinaryOperatorToken, + right: Expression, + leftType: Type, + rightType: Type, + checkMode?: CheckMode, + errorNode?: Node, + ): Type { + const operator = operatorToken.kind; + switch (operator) { + case SyntaxKind.AsteriskToken: + case SyntaxKind.AsteriskAsteriskToken: + case SyntaxKind.AsteriskEqualsToken: + case SyntaxKind.AsteriskAsteriskEqualsToken: + case SyntaxKind.SlashToken: + case SyntaxKind.SlashEqualsToken: + case SyntaxKind.PercentToken: + case SyntaxKind.PercentEqualsToken: + case SyntaxKind.MinusToken: + case SyntaxKind.MinusEqualsToken: + case SyntaxKind.LessThanLessThanToken: + case SyntaxKind.LessThanLessThanEqualsToken: + case SyntaxKind.GreaterThanGreaterThanToken: + case SyntaxKind.GreaterThanGreaterThanEqualsToken: + case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: + case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken: + case SyntaxKind.BarToken: + case SyntaxKind.BarEqualsToken: + case SyntaxKind.CaretToken: + case SyntaxKind.CaretEqualsToken: + case SyntaxKind.AmpersandToken: + case SyntaxKind.AmpersandEqualsToken: + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + + leftType = checkNonNullType(leftType, left); + rightType = checkNonNullType(rightType, right); + + let suggestedOperator: PunctuationSyntaxKind | undefined; + // if a user tries to apply a bitwise operator to 2 boolean operands + // try and return them a helpful suggestion + if ( + (leftType.flags & TypeFlags.BooleanLike) && + (rightType.flags & TypeFlags.BooleanLike) && + (suggestedOperator = getSuggestedBooleanOperator(operatorToken.kind)) !== undefined + ) { + error(errorNode || operatorToken, Diagnostics.The_0_operator_is_not_allowed_for_boolean_types_Consider_using_1_instead, tokenToString(operatorToken.kind), tokenToString(suggestedOperator)); + return numberType; + } + else { + // otherwise just check each operand separately and report errors as normal + const leftOk = checkArithmeticOperandType(left, leftType, Diagnostics.The_left_hand_side_of_an_arithmetic_operation_must_be_of_type_any_number_bigint_or_an_enum_type, /*isAwaitValid*/ true); + const rightOk = checkArithmeticOperandType(right, rightType, Diagnostics.The_right_hand_side_of_an_arithmetic_operation_must_be_of_type_any_number_bigint_or_an_enum_type, /*isAwaitValid*/ true); + let resultType: Type; + // If both are any or unknown, allow operation; assume it will resolve to number + if ( + (isTypeAssignableToKind(leftType, TypeFlags.AnyOrUnknown) && isTypeAssignableToKind(rightType, TypeFlags.AnyOrUnknown)) || + // Or, if neither could be bigint, implicit coercion results in a number result + !(maybeTypeOfKind(leftType, TypeFlags.BigIntLike) || maybeTypeOfKind(rightType, TypeFlags.BigIntLike)) + ) { + resultType = numberType; + } + // At least one is assignable to bigint, so check that both are + else if (bothAreBigIntLike(leftType, rightType)) { + switch (operator) { + case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: + case SyntaxKind.GreaterThanGreaterThanGreaterThanEqualsToken: + reportOperatorError(); + break; + case SyntaxKind.AsteriskAsteriskToken: + case SyntaxKind.AsteriskAsteriskEqualsToken: + if (languageVersion < ScriptTarget.ES2016) { + error(errorNode, Diagnostics.Exponentiation_cannot_be_performed_on_bigint_values_unless_the_target_option_is_set_to_es2016_or_later); + } + } + resultType = bigintType; + } + // Exactly one of leftType/rightType is assignable to bigint + else { + reportOperatorError(bothAreBigIntLike); + resultType = errorType; + } + if (leftOk && rightOk) { + checkAssignmentOperator(resultType); + } + return resultType; + } + case SyntaxKind.PlusToken: + case SyntaxKind.PlusEqualsToken: + if (leftType === silentNeverType || rightType === silentNeverType) { + return silentNeverType; + } + + if (!isTypeAssignableToKind(leftType, TypeFlags.StringLike) && !isTypeAssignableToKind(rightType, TypeFlags.StringLike)) { + leftType = checkNonNullType(leftType, left); + rightType = checkNonNullType(rightType, right); + } + + let resultType: Type | undefined; + if (isTypeAssignableToKind(leftType, TypeFlags.NumberLike, /*strict*/ true) && isTypeAssignableToKind(rightType, TypeFlags.NumberLike, /*strict*/ true)) { + // Operands of an enum type are treated as having the primitive type Number. + // If both operands are of the Number primitive type, the result is of the Number primitive type. + resultType = numberType; + } + else if (isTypeAssignableToKind(leftType, TypeFlags.BigIntLike, /*strict*/ true) && isTypeAssignableToKind(rightType, TypeFlags.BigIntLike, /*strict*/ true)) { + // If both operands are of the BigInt primitive type, the result is of the BigInt primitive type. + resultType = bigintType; + } + else if (isTypeAssignableToKind(leftType, TypeFlags.StringLike, /*strict*/ true) || isTypeAssignableToKind(rightType, TypeFlags.StringLike, /*strict*/ true)) { + // If one or both operands are of the String primitive type, the result is of the String primitive type. + resultType = stringType; + } + else if (isTypeAny(leftType) || isTypeAny(rightType)) { + // Otherwise, the result is of type Any. + // NOTE: unknown type here denotes error type. Old compiler treated this case as any type so do we. + resultType = isErrorType(leftType) || isErrorType(rightType) ? errorType : anyType; + } + + // Symbols are not allowed at all in arithmetic expressions + if (resultType && !checkForDisallowedESSymbolOperand(operator)) { + return resultType; + } + + if (!resultType) { + // Types that have a reasonably good chance of being a valid operand type. + // If both types have an awaited type of one of these, we'll assume the user + // might be missing an await without doing an exhaustive check that inserting + // await(s) will actually be a completely valid binary expression. + const closeEnoughKind = TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.AnyOrUnknown; + reportOperatorError((left, right) => + isTypeAssignableToKind(left, closeEnoughKind) && + isTypeAssignableToKind(right, closeEnoughKind) + ); + return anyType; + } + + if (operator === SyntaxKind.PlusEqualsToken) { + checkAssignmentOperator(resultType); + } + return resultType; + case SyntaxKind.LessThanToken: + case SyntaxKind.GreaterThanToken: + case SyntaxKind.LessThanEqualsToken: + case SyntaxKind.GreaterThanEqualsToken: + if (checkForDisallowedESSymbolOperand(operator)) { + leftType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(leftType, left)); + rightType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(rightType, right)); + reportOperatorErrorUnless((left, right) => { + if (isTypeAny(left) || isTypeAny(right)) { + return true; + } + const leftAssignableToNumber = isTypeAssignableTo(left, numberOrBigIntType); + const rightAssignableToNumber = isTypeAssignableTo(right, numberOrBigIntType); + return leftAssignableToNumber && rightAssignableToNumber || + !leftAssignableToNumber && !rightAssignableToNumber && areTypesComparable(left, right); + }); + } + return booleanType; + case SyntaxKind.EqualsEqualsToken: + case SyntaxKind.ExclamationEqualsToken: + case SyntaxKind.EqualsEqualsEqualsToken: + case SyntaxKind.ExclamationEqualsEqualsToken: + // We suppress errors in CheckMode.TypeOnly (meaning the invocation came from getTypeOfExpression). During + // control flow analysis it is possible for operands to temporarily have narrower types, and those narrower + // types may cause the operands to not be comparable. We don't want such errors reported (see #46475). + if (!(checkMode && checkMode & CheckMode.TypeOnly)) { + if ( + (isLiteralExpressionOfObject(left) || isLiteralExpressionOfObject(right)) && + // only report for === and !== in JS, not == or != + (!isInJSFile(left) || (operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken)) + ) { + const eqType = operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken; + error(errorNode, Diagnostics.This_condition_will_always_return_0_since_JavaScript_compares_objects_by_reference_not_value, eqType ? "false" : "true"); + } + checkNaNEquality(errorNode, operator, left, right); + reportOperatorErrorUnless((left, right) => isTypeEqualityComparableTo(left, right) || isTypeEqualityComparableTo(right, left)); + } + return booleanType; + case SyntaxKind.InstanceOfKeyword: + return checkInstanceOfExpression(left, right, leftType, rightType, checkMode); + case SyntaxKind.InKeyword: + return checkInExpression(left, right, leftType, rightType); + case SyntaxKind.AmpersandAmpersandToken: + case SyntaxKind.AmpersandAmpersandEqualsToken: { + const resultType = hasTypeFacts(leftType, TypeFacts.Truthy) ? + getUnionType([extractDefinitelyFalsyTypes(strictNullChecks ? leftType : getBaseTypeOfLiteralType(rightType)), rightType]) : + leftType; + if (operator === SyntaxKind.AmpersandAmpersandEqualsToken) { + checkAssignmentOperator(rightType); + } + return resultType; + } + case SyntaxKind.BarBarToken: + case SyntaxKind.BarBarEqualsToken: { + const resultType = hasTypeFacts(leftType, TypeFacts.Falsy) ? + getUnionType([getNonNullableType(removeDefinitelyFalsyTypes(leftType)), rightType], UnionReduction.Subtype) : + leftType; + if (operator === SyntaxKind.BarBarEqualsToken) { + checkAssignmentOperator(rightType); + } + return resultType; + } + case SyntaxKind.QuestionQuestionToken: + case SyntaxKind.QuestionQuestionEqualsToken: { + const resultType = hasTypeFacts(leftType, TypeFacts.EQUndefinedOrNull) ? + getUnionType([getNonNullableType(leftType), rightType], UnionReduction.Subtype) : + leftType; + if (operator === SyntaxKind.QuestionQuestionEqualsToken) { + checkAssignmentOperator(rightType); + } + return resultType; + } + case SyntaxKind.EqualsToken: + const declKind = isBinaryExpression(left.parent) ? getAssignmentDeclarationKind(left.parent) : AssignmentDeclarationKind.None; + checkAssignmentDeclaration(declKind, rightType); + if (isAssignmentDeclaration(declKind)) { + if ( + !(rightType.flags & TypeFlags.Object) || + declKind !== AssignmentDeclarationKind.ModuleExports && + declKind !== AssignmentDeclarationKind.Prototype && + !isEmptyObjectType(rightType) && + !isFunctionObjectType(rightType as ObjectType) && + !(getObjectFlags(rightType) & ObjectFlags.Class) + ) { + // don't check assignability of module.exports=, C.prototype=, or expando types because they will necessarily be incomplete + checkAssignmentOperator(rightType); + } + return leftType; + } + else { + checkAssignmentOperator(rightType); + return rightType; + } + case SyntaxKind.CommaToken: + if (!compilerOptions.allowUnreachableCode && isSideEffectFree(left) && !isIndirectCall(left.parent as BinaryExpression)) { + const sf = getSourceFileOfNode(left); + const sourceText = sf.text; + const start = skipTrivia(sourceText, left.pos); + const isInDiag2657 = sf.parseDiagnostics.some(diag => { + if (diag.code !== Diagnostics.JSX_expressions_must_have_one_parent_element.code) return false; + return textSpanContainsPosition(diag, start); + }); + if (!isInDiag2657) error(left, Diagnostics.Left_side_of_comma_operator_is_unused_and_has_no_side_effects); + } + return rightType; + + default: + return Debug.fail(); + } + + function bothAreBigIntLike(left: Type, right: Type): boolean { + return isTypeAssignableToKind(left, TypeFlags.BigIntLike) && isTypeAssignableToKind(right, TypeFlags.BigIntLike); + } + + function checkAssignmentDeclaration(kind: AssignmentDeclarationKind, rightType: Type) { + if (kind === AssignmentDeclarationKind.ModuleExports) { + for (const prop of getPropertiesOfObjectType(rightType)) { + const propType = getTypeOfSymbol(prop); + if (propType.symbol && propType.symbol.flags & SymbolFlags.Class) { + const name = prop.escapedName; + const symbol = resolveName(prop.valueDeclaration, name, SymbolFlags.Type, /*nameNotFoundMessage*/ undefined, /*isUse*/ false); + if (symbol?.declarations && symbol.declarations.some(isJSDocTypedefTag)) { + addDuplicateDeclarationErrorsForSymbols(symbol, Diagnostics.Duplicate_identifier_0, unescapeLeadingUnderscores(name), prop); + addDuplicateDeclarationErrorsForSymbols(prop, Diagnostics.Duplicate_identifier_0, unescapeLeadingUnderscores(name), symbol); + } + } + } + } + } + + // Return true for "indirect calls", (i.e. `(0, x.f)(...)` or `(0, eval)(...)`), which prevents passing `this`. + function isIndirectCall(node: BinaryExpression): boolean { + return node.parent.kind === SyntaxKind.ParenthesizedExpression && + isNumericLiteral(node.left) && + node.left.text === "0" && + (isCallExpression(node.parent.parent) && node.parent.parent.expression === node.parent || node.parent.parent.kind === SyntaxKind.TaggedTemplateExpression) && + // special-case for "eval" because it's the only non-access case where an indirect call actually affects behavior. + (isAccessExpression(node.right) || isIdentifier(node.right) && node.right.escapedText === "eval"); + } + + // Return true if there was no error, false if there was an error. + function checkForDisallowedESSymbolOperand(operator: PunctuationSyntaxKind): boolean { + const offendingSymbolOperand = maybeTypeOfKindConsideringBaseConstraint(leftType, TypeFlags.ESSymbolLike) ? left : + maybeTypeOfKindConsideringBaseConstraint(rightType, TypeFlags.ESSymbolLike) ? right : + undefined; + + if (offendingSymbolOperand) { + error(offendingSymbolOperand, Diagnostics.The_0_operator_cannot_be_applied_to_type_symbol, tokenToString(operator)); + return false; + } + + return true; + } + + function getSuggestedBooleanOperator(operator: SyntaxKind): PunctuationSyntaxKind | undefined { + switch (operator) { + case SyntaxKind.BarToken: + case SyntaxKind.BarEqualsToken: + return SyntaxKind.BarBarToken; + case SyntaxKind.CaretToken: + case SyntaxKind.CaretEqualsToken: + return SyntaxKind.ExclamationEqualsEqualsToken; + case SyntaxKind.AmpersandToken: + case SyntaxKind.AmpersandEqualsToken: + return SyntaxKind.AmpersandAmpersandToken; + default: + return undefined; + } + } + + function checkAssignmentOperator(valueType: Type): void { + if (isAssignmentOperator(operator)) { + addLazyDiagnostic(checkAssignmentOperatorWorker); + } + + function checkAssignmentOperatorWorker() { + let assigneeType = leftType; + + // getters can be a subtype of setters, so to check for assignability we use the setter's type instead + if (isCompoundAssignment(operatorToken.kind) && left.kind === SyntaxKind.PropertyAccessExpression) { + assigneeType = checkPropertyAccessExpression(left as PropertyAccessExpression, /*checkMode*/ undefined, /*writeOnly*/ true); + } + + // TypeScript 1.0 spec (April 2014): 4.17 + // An assignment of the form + // VarExpr = ValueExpr + // requires VarExpr to be classified as a reference + // A compound assignment furthermore requires VarExpr to be classified as a reference (section 4.1) + // and the type of the non-compound operation to be assignable to the type of VarExpr. + + if (checkReferenceExpression(left, Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access, Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access)) { + let headMessage: DiagnosticMessage | undefined; + if (exactOptionalPropertyTypes && isPropertyAccessExpression(left) && maybeTypeOfKind(valueType, TypeFlags.Undefined)) { + const target = getTypeOfPropertyOfType(getTypeOfExpression(left.expression), left.name.escapedText); + if (isExactOptionalPropertyMismatch(valueType, target)) { + headMessage = Diagnostics.Type_0_is_not_assignable_to_type_1_with_exactOptionalPropertyTypes_Colon_true_Consider_adding_undefined_to_the_type_of_the_target; + } + } + // to avoid cascading errors check assignability only if 'isReference' check succeeded and no errors were reported + checkTypeAssignableToAndOptionallyElaborate(valueType, assigneeType, left, right, headMessage); + } + } + } + + function isAssignmentDeclaration(kind: AssignmentDeclarationKind) { + switch (kind) { + case AssignmentDeclarationKind.ModuleExports: + return true; + case AssignmentDeclarationKind.ExportsProperty: + case AssignmentDeclarationKind.Property: + case AssignmentDeclarationKind.Prototype: + case AssignmentDeclarationKind.PrototypeProperty: + case AssignmentDeclarationKind.ThisProperty: + const symbol = getSymbolOfNode(left); + const init = getAssignedExpandoInitializer(right); + return !!init && isObjectLiteralExpression(init) && + !!symbol?.exports?.size; + default: + return false; + } + } + + /** + * Returns true if an error is reported + */ + function reportOperatorErrorUnless(typesAreCompatible: (left: Type, right: Type) => boolean): boolean { + if (!typesAreCompatible(leftType, rightType)) { + reportOperatorError(typesAreCompatible); + return true; + } + return false; + } + + function reportOperatorError(isRelated?: (left: Type, right: Type) => boolean) { + let wouldWorkWithAwait = false; + const errNode = errorNode || operatorToken; + if (isRelated) { + const awaitedLeftType = getAwaitedTypeNoAlias(leftType); + const awaitedRightType = getAwaitedTypeNoAlias(rightType); + wouldWorkWithAwait = !(awaitedLeftType === leftType && awaitedRightType === rightType) + && !!(awaitedLeftType && awaitedRightType) + && isRelated(awaitedLeftType, awaitedRightType); + } + + let effectiveLeft = leftType; + let effectiveRight = rightType; + if (!wouldWorkWithAwait && isRelated) { + [effectiveLeft, effectiveRight] = getBaseTypesIfUnrelated(leftType, rightType, isRelated); + } + const [leftStr, rightStr] = getTypeNamesForErrorDisplay(effectiveLeft, effectiveRight); + if (!tryGiveBetterPrimaryError(errNode, wouldWorkWithAwait, leftStr, rightStr)) { + errorAndMaybeSuggestAwait( + errNode, + wouldWorkWithAwait, + Diagnostics.Operator_0_cannot_be_applied_to_types_1_and_2, + tokenToString(operatorToken.kind), + leftStr, + rightStr, + ); + } + } + + function tryGiveBetterPrimaryError(errNode: Node, maybeMissingAwait: boolean, leftStr: string, rightStr: string) { + switch (operatorToken.kind) { + case SyntaxKind.EqualsEqualsEqualsToken: + case SyntaxKind.EqualsEqualsToken: + case SyntaxKind.ExclamationEqualsEqualsToken: + case SyntaxKind.ExclamationEqualsToken: + return errorAndMaybeSuggestAwait( + errNode, + maybeMissingAwait, + Diagnostics.This_comparison_appears_to_be_unintentional_because_the_types_0_and_1_have_no_overlap, + leftStr, + rightStr, + ); + default: + return undefined; + } + } + + function checkNaNEquality(errorNode: Node | undefined, operator: SyntaxKind, left: Expression, right: Expression) { + const isLeftNaN = isGlobalNaN(skipParentheses(left)); + const isRightNaN = isGlobalNaN(skipParentheses(right)); + if (isLeftNaN || isRightNaN) { + const err = error(errorNode, Diagnostics.This_condition_will_always_return_0, tokenToString(operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.EqualsEqualsToken ? SyntaxKind.FalseKeyword : SyntaxKind.TrueKeyword)); + if (isLeftNaN && isRightNaN) return; + const operatorString = operator === SyntaxKind.ExclamationEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsToken ? tokenToString(SyntaxKind.ExclamationToken) : ""; + const location = isLeftNaN ? right : left; + const expression = skipParentheses(location); + addRelatedInfo(err, createDiagnosticForNode(location, Diagnostics.Did_you_mean_0, `${operatorString}Number.isNaN(${isEntityNameExpression(expression) ? entityNameToString(expression) : "..."})`)); + } + } + + function isGlobalNaN(expr: Expression): boolean { + if (isIdentifier(expr) && expr.escapedText === "NaN") { + const globalNaNSymbol = getGlobalNaNSymbol(); + return !!globalNaNSymbol && globalNaNSymbol === getResolvedSymbol(expr); + } + return false; + } + } + + function getBaseTypesIfUnrelated(leftType: Type, rightType: Type, isRelated: (left: Type, right: Type) => boolean): [Type, Type] { + let effectiveLeft = leftType; + let effectiveRight = rightType; + const leftBase = getBaseTypeOfLiteralType(leftType); + const rightBase = getBaseTypeOfLiteralType(rightType); + if (!isRelated(leftBase, rightBase)) { + effectiveLeft = leftBase; + effectiveRight = rightBase; + } + return [effectiveLeft, effectiveRight]; + } + + function checkYieldExpression(node: YieldExpression): Type { + addLazyDiagnostic(checkYieldExpressionGrammar); + + const func = getContainingFunction(node); + if (!func) return anyType; + const functionFlags = getFunctionFlags(func); + + if (!(functionFlags & FunctionFlags.Generator)) { + // If the user's code is syntactically correct, the func should always have a star. After all, we are in a yield context. + return anyType; + } + + const isAsync = (functionFlags & FunctionFlags.Async) !== 0; + if (node.asteriskToken) { + // Async generator functions prior to ES2018 require the __await, __asyncDelegator, + // and __asyncValues helpers + if (isAsync && languageVersion < LanguageFeatureMinimumTarget.AsyncGenerators) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.AsyncDelegatorIncludes); + } + + // Generator functions prior to ES2015 require the __values helper + if (!isAsync && languageVersion < LanguageFeatureMinimumTarget.Generators && compilerOptions.downlevelIteration) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Values); + } + } + + // There is no point in doing an assignability check if the function + // has no explicit return type because the return type is directly computed + // from the yield expressions. + let returnType = getReturnTypeFromAnnotation(func); + if (returnType && returnType.flags & TypeFlags.Union) { + returnType = filterType(returnType, t => checkGeneratorInstantiationAssignabilityToReturnType(t, functionFlags, /*errorNode*/ undefined)); + } + const iterationTypes = returnType && getIterationTypesOfGeneratorFunctionReturnType(returnType, isAsync); + const signatureYieldType = iterationTypes && iterationTypes.yieldType || anyType; + const signatureNextType = iterationTypes && iterationTypes.nextType || anyType; + const resolvedSignatureNextType = isAsync ? getAwaitedType(signatureNextType) || anyType : signatureNextType; + const yieldExpressionType = node.expression ? checkExpression(node.expression) : undefinedWideningType; + const yieldedType = getYieldedTypeOfYieldExpression(node, yieldExpressionType, resolvedSignatureNextType, isAsync); + if (returnType && yieldedType) { + checkTypeAssignableToAndOptionallyElaborate(yieldedType, signatureYieldType, node.expression || node, node.expression); + } + + if (node.asteriskToken) { + const use = isAsync ? IterationUse.AsyncYieldStar : IterationUse.YieldStar; + return getIterationTypeOfIterable(use, IterationTypeKind.Return, yieldExpressionType, node.expression) + || anyType; + } + else if (returnType) { + return getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Next, returnType, isAsync) + || anyType; + } + let type = getContextualIterationType(IterationTypeKind.Next, func); + if (!type) { + type = anyType; + addLazyDiagnostic(() => { + if (noImplicitAny && !expressionResultIsUnused(node)) { + const contextualType = getContextualType(node, /*contextFlags*/ undefined); + if (!contextualType || isTypeAny(contextualType)) { + error(node, Diagnostics.yield_expression_implicitly_results_in_an_any_type_because_its_containing_generator_lacks_a_return_type_annotation); + } + } + }); + } + return type; + + function checkYieldExpressionGrammar() { + if (!(node.flags & NodeFlags.YieldContext)) { + grammarErrorOnFirstToken(node, Diagnostics.A_yield_expression_is_only_allowed_in_a_generator_body); + } + + if (isInParameterInitializerBeforeContainingFunction(node)) { + error(node, Diagnostics.yield_expressions_cannot_be_used_in_a_parameter_initializer); + } + } + } + + function checkConditionalExpression(node: ConditionalExpression, checkMode?: CheckMode): Type { + const type = checkTruthinessExpression(node.condition, checkMode); + checkTestingKnownTruthyCallableOrAwaitableOrEnumMemberType(node.condition, type, node.whenTrue); + const type1 = checkExpression(node.whenTrue, checkMode); + const type2 = checkExpression(node.whenFalse, checkMode); + return getUnionType([type1, type2], UnionReduction.Subtype); + } + + function isTemplateLiteralContext(node: Node): boolean { + const parent = node.parent; + return isParenthesizedExpression(parent) && isTemplateLiteralContext(parent) || + isElementAccessExpression(parent) && parent.argumentExpression === node; + } + + function checkTemplateExpression(node: TemplateExpression): Type { + const texts = [node.head.text]; + const types = []; + for (const span of node.templateSpans) { + const type = checkExpression(span.expression); + if (maybeTypeOfKindConsideringBaseConstraint(type, TypeFlags.ESSymbolLike)) { + error(span.expression, Diagnostics.Implicit_conversion_of_a_symbol_to_a_string_will_fail_at_runtime_Consider_wrapping_this_expression_in_String); + } + texts.push(span.literal.text); + types.push(isTypeAssignableTo(type, templateConstraintType) ? type : stringType); + } + const evaluated = node.parent.kind !== SyntaxKind.TaggedTemplateExpression && evaluate(node).value; + if (evaluated) { + return getFreshTypeOfLiteralType(getStringLiteralType(evaluated)); + } + if (isConstContext(node) || isTemplateLiteralContext(node) || someType(getContextualType(node, /*contextFlags*/ undefined) || unknownType, isTemplateLiteralContextualType)) { + return getTemplateLiteralType(texts, types); + } + return stringType; + } + + function isTemplateLiteralContextualType(type: Type): boolean { + return !!(type.flags & (TypeFlags.StringLiteral | TypeFlags.TemplateLiteral) || + type.flags & TypeFlags.InstantiableNonPrimitive && maybeTypeOfKind(getBaseConstraintOfType(type) || unknownType, TypeFlags.StringLike)); + } + + function getContextNode(node: Expression): Expression { + if (isJsxAttributes(node) && !isJsxSelfClosingElement(node.parent)) { + return node.parent.parent; // Needs to be the root JsxElement, so it encompasses the attributes _and_ the children (which are essentially part of the attributes) + } + return node; + } + + function checkExpressionWithContextualType(node: Expression, contextualType: Type, inferenceContext: InferenceContext | undefined, checkMode: CheckMode): Type { + const contextNode = getContextNode(node); + pushContextualType(contextNode, contextualType, /*isCache*/ false); + pushInferenceContext(contextNode, inferenceContext); + const type = checkExpression(node, checkMode | CheckMode.Contextual | (inferenceContext ? CheckMode.Inferential : 0)); + // In CheckMode.Inferential we collect intra-expression inference sites to process before fixing any type + // parameters. This information is no longer needed after the call to checkExpression. + if (inferenceContext && inferenceContext.intraExpressionInferenceSites) { + inferenceContext.intraExpressionInferenceSites = undefined; + } + // We strip literal freshness when an appropriate contextual type is present such that contextually typed + // literals always preserve their literal types (otherwise they might widen during type inference). An alternative + // here would be to not mark contextually typed literals as fresh in the first place. + const result = maybeTypeOfKind(type, TypeFlags.Literal) && isLiteralOfContextualType(type, instantiateContextualType(contextualType, node, /*contextFlags*/ undefined)) ? + getRegularTypeOfLiteralType(type) : type; + popInferenceContext(); + popContextualType(); + return result; + } + + function checkExpressionCached(node: Expression | QualifiedName, checkMode?: CheckMode): Type { + if (checkMode) { + return checkExpression(node, checkMode); + } + const links = getNodeLinks(node); + if (!links.resolvedType) { + // When computing a type that we're going to cache, we need to ignore any ongoing control flow + // analysis because variables may have transient types in indeterminable states. Moving flowLoopStart + // to the top of the stack ensures all transient types are computed from a known point. + const saveFlowLoopStart = flowLoopStart; + const saveFlowTypeCache = flowTypeCache; + flowLoopStart = flowLoopCount; + flowTypeCache = undefined; + links.resolvedType = checkExpression(node, checkMode); + flowTypeCache = saveFlowTypeCache; + flowLoopStart = saveFlowLoopStart; + } + return links.resolvedType; + } + + function isTypeAssertion(node: Expression) { + node = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + return node.kind === SyntaxKind.TypeAssertionExpression || + node.kind === SyntaxKind.AsExpression || + isJSDocTypeAssertion(node); + } + + function checkDeclarationInitializer( + declaration: HasExpressionInitializer, + checkMode: CheckMode, + contextualType?: Type | undefined, + ) { + const initializer = getEffectiveInitializer(declaration)!; + if (isInJSFile(declaration)) { + const typeNode = tryGetJSDocSatisfiesTypeNode(declaration); + if (typeNode) { + return checkSatisfiesExpressionWorker(initializer, typeNode, checkMode); + } + } + const type = getQuickTypeOfExpression(initializer) || + (contextualType ? + checkExpressionWithContextualType(initializer, contextualType, /*inferenceContext*/ undefined, checkMode || CheckMode.Normal) + : checkExpressionCached(initializer, checkMode)); + return isParameter(declaration) && declaration.name.kind === SyntaxKind.ArrayBindingPattern && + isTupleType(type) && !(type.target.combinedFlags & ElementFlags.Variable) && getTypeReferenceArity(type) < declaration.name.elements.length ? + padTupleType(type, declaration.name) : type; + } + + function padTupleType(type: TupleTypeReference, pattern: ArrayBindingPattern) { + const patternElements = pattern.elements; + const elementTypes = getElementTypes(type).slice(); + const elementFlags = type.target.elementFlags.slice(); + for (let i = getTypeReferenceArity(type); i < patternElements.length; i++) { + const e = patternElements[i]; + if (i < patternElements.length - 1 || !(e.kind === SyntaxKind.BindingElement && e.dotDotDotToken)) { + elementTypes.push(!isOmittedExpression(e) && hasDefaultValue(e) ? getTypeFromBindingElement(e, /*includePatternInType*/ false, /*reportErrors*/ false) : anyType); + elementFlags.push(ElementFlags.Optional); + if (!isOmittedExpression(e) && !hasDefaultValue(e)) { + reportImplicitAny(e, anyType); + } + } + } + return createTupleType(elementTypes, elementFlags, type.target.readonly); + } + + function widenTypeInferredFromInitializer(declaration: HasExpressionInitializer, type: Type) { + const widened = getCombinedNodeFlagsCached(declaration) & NodeFlags.Constant || isDeclarationReadonly(declaration) ? type : getWidenedLiteralType(type); + if (isInJSFile(declaration)) { + if (isEmptyLiteralType(widened)) { + reportImplicitAny(declaration, anyType); + return anyType; + } + else if (isEmptyArrayLiteralType(widened)) { + reportImplicitAny(declaration, anyArrayType); + return anyArrayType; + } + } + return widened; + } + + function isLiteralOfContextualType(candidateType: Type, contextualType: Type | undefined): boolean { + if (contextualType) { + if (contextualType.flags & TypeFlags.UnionOrIntersection) { + const types = (contextualType as UnionType).types; + return some(types, t => isLiteralOfContextualType(candidateType, t)); + } + if (contextualType.flags & TypeFlags.InstantiableNonPrimitive) { + // If the contextual type is a type variable constrained to a primitive type, consider + // this a literal context for literals of that primitive type. For example, given a + // type parameter 'T extends string', infer string literal types for T. + const constraint = getBaseConstraintOfType(contextualType) || unknownType; + return maybeTypeOfKind(constraint, TypeFlags.String) && maybeTypeOfKind(candidateType, TypeFlags.StringLiteral) || + maybeTypeOfKind(constraint, TypeFlags.Number) && maybeTypeOfKind(candidateType, TypeFlags.NumberLiteral) || + maybeTypeOfKind(constraint, TypeFlags.BigInt) && maybeTypeOfKind(candidateType, TypeFlags.BigIntLiteral) || + maybeTypeOfKind(constraint, TypeFlags.ESSymbol) && maybeTypeOfKind(candidateType, TypeFlags.UniqueESSymbol) || + isLiteralOfContextualType(candidateType, constraint); + } + // If the contextual type is a literal of a particular primitive type, we consider this a + // literal context for all literals of that primitive type. + return !!(contextualType.flags & (TypeFlags.StringLiteral | TypeFlags.Index | TypeFlags.TemplateLiteral | TypeFlags.StringMapping) && maybeTypeOfKind(candidateType, TypeFlags.StringLiteral) || + contextualType.flags & TypeFlags.NumberLiteral && maybeTypeOfKind(candidateType, TypeFlags.NumberLiteral) || + contextualType.flags & TypeFlags.BigIntLiteral && maybeTypeOfKind(candidateType, TypeFlags.BigIntLiteral) || + contextualType.flags & TypeFlags.BooleanLiteral && maybeTypeOfKind(candidateType, TypeFlags.BooleanLiteral) || + contextualType.flags & TypeFlags.UniqueESSymbol && maybeTypeOfKind(candidateType, TypeFlags.UniqueESSymbol)); + } + return false; + } + + function isConstContext(node: Expression): boolean { + const parent = node.parent; + return isAssertionExpression(parent) && isConstTypeReference(parent.type) || + isJSDocTypeAssertion(parent) && isConstTypeReference(getJSDocTypeAssertionType(parent)) || + isValidConstAssertionArgument(node) && isConstTypeVariable(getContextualType(node, ContextFlags.None)) || + (isParenthesizedExpression(parent) || isArrayLiteralExpression(parent) || isSpreadElement(parent)) && isConstContext(parent) || + (isPropertyAssignment(parent) || isShorthandPropertyAssignment(parent) || isTemplateSpan(parent)) && isConstContext(parent.parent); + } + + function checkExpressionForMutableLocation(node: Expression, checkMode: CheckMode | undefined, forceTuple?: boolean): Type { + const type = checkExpression(node, checkMode, forceTuple); + return isConstContext(node) || isCommonJsExportedExpression(node) ? getRegularTypeOfLiteralType(type) : + isTypeAssertion(node) ? type : + getWidenedLiteralLikeTypeForContextualType(type, instantiateContextualType(getContextualType(node, /*contextFlags*/ undefined), node, /*contextFlags*/ undefined)); + } + + function checkPropertyAssignment(node: PropertyAssignment, checkMode?: CheckMode): Type { + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + } + + return checkExpressionForMutableLocation(node.initializer, checkMode); + } + + function checkObjectLiteralMethod(node: MethodDeclaration, checkMode?: CheckMode): Type { + // Grammar checking + checkGrammarMethod(node); + + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + } + + const uninstantiatedType = checkFunctionExpressionOrObjectLiteralMethod(node, checkMode); + return instantiateTypeWithSingleGenericCallSignature(node, uninstantiatedType, checkMode); + } + + function instantiateTypeWithSingleGenericCallSignature(node: Expression | MethodDeclaration | QualifiedName, type: Type, checkMode?: CheckMode) { + if (checkMode && checkMode & (CheckMode.Inferential | CheckMode.SkipGenericFunctions)) { + const callSignature = getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ true); + const constructSignature = getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ true); + const signature = callSignature || constructSignature; + if (signature && signature.typeParameters) { + const contextualType = getApparentTypeOfContextualType(node as Expression, ContextFlags.NoConstraints); + if (contextualType) { + const contextualSignature = getSingleSignature(getNonNullableType(contextualType), callSignature ? SignatureKind.Call : SignatureKind.Construct, /*allowMembers*/ false); + if (contextualSignature && !contextualSignature.typeParameters) { + if (checkMode & CheckMode.SkipGenericFunctions) { + skippedGenericFunction(node, checkMode); + return anyFunctionType; + } + const context = getInferenceContext(node)!; + // We have an expression that is an argument of a generic function for which we are performing + // type argument inference. The expression is of a function type with a single generic call + // signature and a contextual function type with a single non-generic call signature. Now check + // if the outer function returns a function type with a single non-generic call signature and + // if some of the outer function type parameters have no inferences so far. If so, we can + // potentially add inferred type parameters to the outer function return type. + const returnType = context.signature && getReturnTypeOfSignature(context.signature); + const returnSignature = returnType && getSingleCallOrConstructSignature(returnType); + if (returnSignature && !returnSignature.typeParameters && !every(context.inferences, hasInferenceCandidates)) { + // Instantiate the signature with its own type parameters as type arguments, possibly + // renaming the type parameters to ensure they have unique names. + const uniqueTypeParameters = getUniqueTypeParameters(context, signature.typeParameters); + const instantiatedSignature = getSignatureInstantiationWithoutFillingInTypeArguments(signature, uniqueTypeParameters); + // Infer from the parameters of the instantiated signature to the parameters of the + // contextual signature starting with an empty set of inference candidates. + const inferences = map(context.inferences, info => createInferenceInfo(info.typeParameter)); + applyToParameterTypes(instantiatedSignature, contextualSignature, (source, target) => { + inferTypes(inferences, source, target, /*priority*/ 0, /*contravariant*/ true); + }); + if (some(inferences, hasInferenceCandidates)) { + // We have inference candidates, indicating that one or more type parameters are referenced + // in the parameter types of the contextual signature. Now also infer from the return type. + applyToReturnTypes(instantiatedSignature, contextualSignature, (source, target) => { + inferTypes(inferences, source, target); + }); + // If the type parameters for which we produced candidates do not have any inferences yet, + // we adopt the new inference candidates and add the type parameters of the expression type + // to the set of inferred type parameters for the outer function return type. + if (!hasOverlappingInferences(context.inferences, inferences)) { + mergeInferences(context.inferences, inferences); + context.inferredTypeParameters = concatenate(context.inferredTypeParameters, uniqueTypeParameters); + return getOrCreateTypeFromSignature(instantiatedSignature); + } + } + } + // TODO: The signature may reference any outer inference contexts, but we map pop off and then apply new inference contexts, and thus get different inferred types. + // That this is cached on the *first* such attempt is not currently an issue, since expression types *also* get cached on the first pass. If we ever properly speculate, though, + // the cached "isolatedSignatureType" signature field absolutely needs to be included in the list of speculative caches. + return getOrCreateTypeFromSignature(instantiateSignatureInContextOf(signature, contextualSignature, context), flatMap(inferenceContexts, c => c && map(c.inferences, i => i.typeParameter)).slice()); + } + } + } + } + return type; + } + + function skippedGenericFunction(node: Node, checkMode: CheckMode) { + if (checkMode & CheckMode.Inferential) { + // We have skipped a generic function during inferential typing. Obtain the inference context and + // indicate this has occurred such that we know a second pass of inference is be needed. + const context = getInferenceContext(node)!; + context.flags |= InferenceFlags.SkippedGenericFunction; + } + } + + function hasInferenceCandidates(info: InferenceInfo) { + return !!(info.candidates || info.contraCandidates); + } + + function hasInferenceCandidatesOrDefault(info: InferenceInfo) { + return !!(info.candidates || info.contraCandidates || hasTypeParameterDefault(info.typeParameter)); + } + + function hasOverlappingInferences(a: InferenceInfo[], b: InferenceInfo[]) { + for (let i = 0; i < a.length; i++) { + if (hasInferenceCandidates(a[i]) && hasInferenceCandidates(b[i])) { + return true; + } + } + return false; + } + + function mergeInferences(target: InferenceInfo[], source: InferenceInfo[]) { + for (let i = 0; i < target.length; i++) { + if (!hasInferenceCandidates(target[i]) && hasInferenceCandidates(source[i])) { + target[i] = source[i]; + } + } + } + + function getUniqueTypeParameters(context: InferenceContext, typeParameters: readonly TypeParameter[]): readonly TypeParameter[] { + const result: TypeParameter[] = []; + let oldTypeParameters: TypeParameter[] | undefined; + let newTypeParameters: TypeParameter[] | undefined; + for (const tp of typeParameters) { + const name = tp.symbol.escapedName; + if (hasTypeParameterByName(context.inferredTypeParameters, name) || hasTypeParameterByName(result, name)) { + const newName = getUniqueTypeParameterName(concatenate(context.inferredTypeParameters, result), name); + const symbol = createSymbol(SymbolFlags.TypeParameter, newName); + const newTypeParameter = createTypeParameter(symbol); + newTypeParameter.target = tp; + oldTypeParameters = append(oldTypeParameters, tp); + newTypeParameters = append(newTypeParameters, newTypeParameter); + result.push(newTypeParameter); + } + else { + result.push(tp); + } + } + if (newTypeParameters) { + const mapper = createTypeMapper(oldTypeParameters!, newTypeParameters); + for (const tp of newTypeParameters) { + tp.mapper = mapper; + } + } + return result; + } + + function hasTypeParameterByName(typeParameters: readonly TypeParameter[] | undefined, name: __String) { + return some(typeParameters, tp => tp.symbol.escapedName === name); + } + + function getUniqueTypeParameterName(typeParameters: readonly TypeParameter[], baseName: __String) { + let len = (baseName as string).length; + while (len > 1 && (baseName as string).charCodeAt(len - 1) >= CharacterCodes._0 && (baseName as string).charCodeAt(len - 1) <= CharacterCodes._9) len--; + const s = (baseName as string).slice(0, len); + for (let index = 1; true; index++) { + const augmentedName = s + index as __String; + if (!hasTypeParameterByName(typeParameters, augmentedName)) { + return augmentedName; + } + } + } + + function getReturnTypeOfSingleNonGenericCallSignature(funcType: Type) { + const signature = getSingleCallSignature(funcType); + if (signature && !signature.typeParameters) { + return getReturnTypeOfSignature(signature); + } + } + + function getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr: CallChain) { + const funcType = checkExpression(expr.expression); + const nonOptionalType = getOptionalExpressionType(funcType, expr.expression); + const returnType = getReturnTypeOfSingleNonGenericCallSignature(funcType); + return returnType && propagateOptionalTypeMarker(returnType, expr, nonOptionalType !== funcType); + } + + /** + * Returns the type of an expression. Unlike checkExpression, this function is simply concerned + * with computing the type and may not fully check all contained sub-expressions for errors. + */ + function getTypeOfExpression(node: Expression) { + // Don't bother caching types that require no flow analysis and are quick to compute. + const quickType = getQuickTypeOfExpression(node); + if (quickType) { + return quickType; + } + // If a type has been cached for the node, return it. + if (node.flags & NodeFlags.TypeCached && flowTypeCache) { + const cachedType = flowTypeCache[getNodeId(node)]; + if (cachedType) { + return cachedType; + } + } + const startInvocationCount = flowInvocationCount; + const type = checkExpression(node, CheckMode.TypeOnly); + // If control flow analysis was required to determine the type, it is worth caching. + if (flowInvocationCount !== startInvocationCount) { + const cache = flowTypeCache || (flowTypeCache = []); + cache[getNodeId(node)] = type; + setNodeFlags(node, node.flags | NodeFlags.TypeCached); + } + return type; + } + + function getQuickTypeOfExpression(node: Expression): Type | undefined { + let expr = skipParentheses(node, /*excludeJSDocTypeAssertions*/ true); + if (isJSDocTypeAssertion(expr)) { + const type = getJSDocTypeAssertionType(expr); + if (!isConstTypeReference(type)) { + return getTypeFromTypeNode(type); + } + } + expr = skipParentheses(node); + if (isAwaitExpression(expr)) { + const type = getQuickTypeOfExpression(expr.expression); + return type ? getAwaitedType(type) : undefined; + } + // Optimize for the common case of a call to a function with a single non-generic call + // signature where we can just fetch the return type without checking the arguments. + if (isCallExpression(expr) && expr.expression.kind !== SyntaxKind.SuperKeyword && !isRequireCall(expr, /*requireStringLiteralLikeArgument*/ true) && !isSymbolOrSymbolForCall(expr)) { + return isCallChain(expr) ? getReturnTypeOfSingleNonGenericSignatureOfCallChain(expr) : + getReturnTypeOfSingleNonGenericCallSignature(checkNonNullExpression(expr.expression)); + } + else if (isAssertionExpression(expr) && !isConstTypeReference(expr.type)) { + return getTypeFromTypeNode((expr as TypeAssertion).type); + } + else if (isLiteralExpression(node) || isBooleanLiteral(node)) { + return checkExpression(node); + } + return undefined; + } + + /** + * Returns the type of an expression. Unlike checkExpression, this function is simply concerned + * with computing the type and may not fully check all contained sub-expressions for errors. + * It is intended for uses where you know there is no contextual type, + * and requesting the contextual type might cause a circularity or other bad behaviour. + * It sets the contextual type of the node to any before calling getTypeOfExpression. + */ + function getContextFreeTypeOfExpression(node: Expression) { + const links = getNodeLinks(node); + if (links.contextFreeType) { + return links.contextFreeType; + } + pushContextualType(node, anyType, /*isCache*/ false); + const type = links.contextFreeType = checkExpression(node, CheckMode.SkipContextSensitive); + popContextualType(); + return type; + } + + function checkExpression(node: Expression | QualifiedName, checkMode?: CheckMode, forceTuple?: boolean): Type { + tracing?.push(tracing.Phase.Check, "checkExpression", { kind: node.kind, pos: node.pos, end: node.end, path: (node as TracingNode).tracingPath }); + const saveCurrentNode = currentNode; + currentNode = node; + instantiationCount = 0; + const uninstantiatedType = checkExpressionWorker(node, checkMode, forceTuple); + const type = instantiateTypeWithSingleGenericCallSignature(node, uninstantiatedType, checkMode); + if (isConstEnumObjectType(type)) { + checkConstEnumAccess(node, type); + } + currentNode = saveCurrentNode; + tracing?.pop(); + return type; + } + + function checkConstEnumAccess(node: Expression | QualifiedName, type: Type) { + // enum object type for const enums are only permitted in: + // - 'left' in property access + // - 'object' in indexed access + // - target in rhs of import statement + const ok = (node.parent.kind === SyntaxKind.PropertyAccessExpression && (node.parent as PropertyAccessExpression).expression === node) || + (node.parent.kind === SyntaxKind.ElementAccessExpression && (node.parent as ElementAccessExpression).expression === node) || + ((node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.QualifiedName) && isInRightSideOfImportOrExportAssignment(node as Identifier) || + (node.parent.kind === SyntaxKind.TypeQuery && (node.parent as TypeQueryNode).exprName === node)) || + (node.parent.kind === SyntaxKind.ExportSpecifier); // We allow reexporting const enums + + if (!ok) { + error(node, Diagnostics.const_enums_can_only_be_used_in_property_or_index_access_expressions_or_the_right_hand_side_of_an_import_declaration_or_export_assignment_or_type_query); + } + + if (getIsolatedModules(compilerOptions)) { + Debug.assert(!!(type.symbol.flags & SymbolFlags.ConstEnum)); + const constEnumDeclaration = type.symbol.valueDeclaration as EnumDeclaration; + const redirect = host.getRedirectReferenceForResolutionFromSourceOfProject(getSourceFileOfNode(constEnumDeclaration).resolvedPath); + if (constEnumDeclaration.flags & NodeFlags.Ambient && !isValidTypeOnlyAliasUseSite(node) && (!redirect || !shouldPreserveConstEnums(redirect.commandLine.options))) { + error(node, Diagnostics.Cannot_access_ambient_const_enums_when_0_is_enabled, isolatedModulesLikeFlagName); + } + } + } + + function checkParenthesizedExpression(node: ParenthesizedExpression, checkMode?: CheckMode): Type { + if (hasJSDocNodes(node)) { + if (isJSDocSatisfiesExpression(node)) { + return checkSatisfiesExpressionWorker(node.expression, getJSDocSatisfiesExpressionType(node), checkMode); + } + if (isJSDocTypeAssertion(node)) { + return checkAssertionWorker(node, checkMode); + } + } + return checkExpression(node.expression, checkMode); + } + + function checkExpressionWorker(node: Expression | QualifiedName, checkMode: CheckMode | undefined, forceTuple?: boolean): Type { + const kind = node.kind; + if (cancellationToken) { + // Only bother checking on a few construct kinds. We don't want to be excessively + // hitting the cancellation token on every node we check. + switch (kind) { + case SyntaxKind.ClassExpression: + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + cancellationToken.throwIfCancellationRequested(); + } + } + switch (kind) { + case SyntaxKind.Identifier: + return checkIdentifier(node as Identifier, checkMode); + case SyntaxKind.PrivateIdentifier: + return checkPrivateIdentifierExpression(node as PrivateIdentifier); + case SyntaxKind.ThisKeyword: + return checkThisExpression(node); + case SyntaxKind.SuperKeyword: + return checkSuperExpression(node); + case SyntaxKind.NullKeyword: + return nullWideningType; + case SyntaxKind.NoSubstitutionTemplateLiteral: + case SyntaxKind.StringLiteral: + return hasSkipDirectInferenceFlag(node) ? + blockedStringType : + getFreshTypeOfLiteralType(getStringLiteralType((node as StringLiteralLike).text)); + case SyntaxKind.NumericLiteral: + checkGrammarNumericLiteral(node as NumericLiteral); + return getFreshTypeOfLiteralType(getNumberLiteralType(+(node as NumericLiteral).text)); + case SyntaxKind.BigIntLiteral: + checkGrammarBigIntLiteral(node as BigIntLiteral); + return getFreshTypeOfLiteralType(getBigIntLiteralType({ + negative: false, + base10Value: parsePseudoBigInt((node as BigIntLiteral).text), + })); + case SyntaxKind.TrueKeyword: + return trueType; + case SyntaxKind.FalseKeyword: + return falseType; + case SyntaxKind.TemplateExpression: + return checkTemplateExpression(node as TemplateExpression); + case SyntaxKind.RegularExpressionLiteral: + return checkRegularExpressionLiteral(node as RegularExpressionLiteral); + case SyntaxKind.ArrayLiteralExpression: + return checkArrayLiteral(node as ArrayLiteralExpression, checkMode, forceTuple); + case SyntaxKind.ObjectLiteralExpression: + return checkObjectLiteral(node as ObjectLiteralExpression, checkMode); + case SyntaxKind.PropertyAccessExpression: + return checkPropertyAccessExpression(node as PropertyAccessExpression, checkMode); + case SyntaxKind.QualifiedName: + return checkQualifiedName(node as QualifiedName, checkMode); + case SyntaxKind.ElementAccessExpression: + return checkIndexedAccess(node as ElementAccessExpression, checkMode); + case SyntaxKind.CallExpression: + if ((node as CallExpression).expression.kind === SyntaxKind.ImportKeyword) { + return checkImportCallExpression(node as ImportCall); + } + // falls through + case SyntaxKind.NewExpression: + return checkCallExpression(node as CallExpression, checkMode); + case SyntaxKind.TaggedTemplateExpression: + return checkTaggedTemplateExpression(node as TaggedTemplateExpression); + case SyntaxKind.ParenthesizedExpression: + return checkParenthesizedExpression(node as ParenthesizedExpression, checkMode); + case SyntaxKind.ClassExpression: + return checkClassExpression(node as ClassExpression); + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + return checkFunctionExpressionOrObjectLiteralMethod(node as FunctionExpression | ArrowFunction, checkMode); + case SyntaxKind.TypeOfExpression: + return checkTypeOfExpression(node as TypeOfExpression); + case SyntaxKind.TypeAssertionExpression: + case SyntaxKind.AsExpression: + return checkAssertion(node as AssertionExpression, checkMode); + case SyntaxKind.NonNullExpression: + return checkNonNullAssertion(node as NonNullExpression); + case SyntaxKind.ExpressionWithTypeArguments: + return checkExpressionWithTypeArguments(node as ExpressionWithTypeArguments); + case SyntaxKind.SatisfiesExpression: + return checkSatisfiesExpression(node as SatisfiesExpression); + case SyntaxKind.MetaProperty: + return checkMetaProperty(node as MetaProperty); + case SyntaxKind.DeleteExpression: + return checkDeleteExpression(node as DeleteExpression); + case SyntaxKind.VoidExpression: + return checkVoidExpression(node as VoidExpression); + case SyntaxKind.AwaitExpression: + return checkAwaitExpression(node as AwaitExpression); + case SyntaxKind.PrefixUnaryExpression: + return checkPrefixUnaryExpression(node as PrefixUnaryExpression); + case SyntaxKind.PostfixUnaryExpression: + return checkPostfixUnaryExpression(node as PostfixUnaryExpression); + case SyntaxKind.BinaryExpression: + return checkBinaryExpression(node as BinaryExpression, checkMode); + case SyntaxKind.ConditionalExpression: + return checkConditionalExpression(node as ConditionalExpression, checkMode); + case SyntaxKind.SpreadElement: + return checkSpreadExpression(node as SpreadElement, checkMode); + case SyntaxKind.OmittedExpression: + return undefinedWideningType; + case SyntaxKind.YieldExpression: + return checkYieldExpression(node as YieldExpression); + case SyntaxKind.SyntheticExpression: + return checkSyntheticExpression(node as SyntheticExpression); + case SyntaxKind.JsxExpression: + return checkJsxExpression(node as JsxExpression, checkMode); + case SyntaxKind.JsxElement: + return checkJsxElement(node as JsxElement, checkMode); + case SyntaxKind.JsxSelfClosingElement: + return checkJsxSelfClosingElement(node as JsxSelfClosingElement, checkMode); + case SyntaxKind.JsxFragment: + return checkJsxFragment(node as JsxFragment); + case SyntaxKind.JsxAttributes: + return checkJsxAttributes(node as JsxAttributes, checkMode); + case SyntaxKind.JsxOpeningElement: + Debug.fail("Shouldn't ever directly check a JsxOpeningElement"); + } + return errorType; + } + + // DECLARATION AND STATEMENT TYPE CHECKING + + function checkTypeParameter(node: TypeParameterDeclaration) { + // Grammar Checking + checkGrammarModifiers(node); + if (node.expression) { + grammarErrorOnFirstToken(node.expression, Diagnostics.Type_expected); + } + + checkSourceElement(node.constraint); + checkSourceElement(node.default); + const typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node)); + // Resolve base constraint to reveal circularity errors + getBaseConstraintOfType(typeParameter); + if (!hasNonCircularTypeParameterDefault(typeParameter)) { + error(node.default, Diagnostics.Type_parameter_0_has_a_circular_default, typeToString(typeParameter)); + } + const constraintType = getConstraintOfTypeParameter(typeParameter); + const defaultType = getDefaultFromTypeParameter(typeParameter); + if (constraintType && defaultType) { + checkTypeAssignableTo(defaultType, getTypeWithThisArgument(instantiateType(constraintType, makeUnaryTypeMapper(typeParameter, defaultType)), defaultType), node.default, Diagnostics.Type_0_does_not_satisfy_the_constraint_1); + } + checkNodeDeferred(node); + addLazyDiagnostic(() => checkTypeNameIsReserved(node.name, Diagnostics.Type_parameter_name_cannot_be_0)); + } + + function checkTypeParameterDeferred(node: TypeParameterDeclaration) { + if (isInterfaceDeclaration(node.parent) || isClassLike(node.parent) || isTypeAliasDeclaration(node.parent)) { + const typeParameter = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node)); + const modifiers = getTypeParameterModifiers(typeParameter) & (ModifierFlags.In | ModifierFlags.Out); + if (modifiers) { + const symbol = getSymbolOfDeclaration(node.parent); + if (isTypeAliasDeclaration(node.parent) && !(getObjectFlags(getDeclaredTypeOfSymbol(symbol)) & (ObjectFlags.Reference | ObjectFlags.Anonymous | ObjectFlags.Mapped))) { + error(node, Diagnostics.Variance_annotations_are_only_supported_in_type_aliases_for_object_function_constructor_and_mapped_types); + } + else if (modifiers === ModifierFlags.In || modifiers === ModifierFlags.Out) { + tracing?.push(tracing.Phase.CheckTypes, "checkTypeParameterDeferred", { parent: getTypeId(getDeclaredTypeOfSymbol(symbol)), id: getTypeId(typeParameter) }); + const source = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSubTypeForCheck : markerSuperTypeForCheck); + const target = createMarkerType(symbol, typeParameter, modifiers === ModifierFlags.Out ? markerSuperTypeForCheck : markerSubTypeForCheck); + const saveVarianceTypeParameter = typeParameter; + varianceTypeParameter = typeParameter; + checkTypeAssignableTo(source, target, node, Diagnostics.Type_0_is_not_assignable_to_type_1_as_implied_by_variance_annotation); + varianceTypeParameter = saveVarianceTypeParameter; + tracing?.pop(); + } + } + } + } + + function checkParameter(node: ParameterDeclaration) { + // Grammar checking + // It is a SyntaxError if the Identifier "eval" or the Identifier "arguments" occurs as the + // Identifier in a PropertySetParameterList of a PropertyAssignment that is contained in strict code + // or if its FunctionBody is strict code(11.1.5). + checkGrammarModifiers(node); + + checkVariableLikeDeclaration(node); + const func = getContainingFunction(node)!; + if (hasSyntacticModifier(node, ModifierFlags.ParameterPropertyModifier)) { + if (!(func.kind === SyntaxKind.Constructor && nodeIsPresent(func.body))) { + error(node, Diagnostics.A_parameter_property_is_only_allowed_in_a_constructor_implementation); + } + if (func.kind === SyntaxKind.Constructor && isIdentifier(node.name) && node.name.escapedText === "constructor") { + error(node.name, Diagnostics.constructor_cannot_be_used_as_a_parameter_property_name); + } + } + if (!node.initializer && isOptionalDeclaration(node) && isBindingPattern(node.name) && (func as FunctionLikeDeclaration).body) { + error(node, Diagnostics.A_binding_pattern_parameter_cannot_be_optional_in_an_implementation_signature); + } + if (node.name && isIdentifier(node.name) && (node.name.escapedText === "this" || node.name.escapedText === "new")) { + if (func.parameters.indexOf(node) !== 0) { + error(node, Diagnostics.A_0_parameter_must_be_the_first_parameter, node.name.escapedText as string); + } + if (func.kind === SyntaxKind.Constructor || func.kind === SyntaxKind.ConstructSignature || func.kind === SyntaxKind.ConstructorType) { + error(node, Diagnostics.A_constructor_cannot_have_a_this_parameter); + } + if (func.kind === SyntaxKind.ArrowFunction) { + error(node, Diagnostics.An_arrow_function_cannot_have_a_this_parameter); + } + if (func.kind === SyntaxKind.GetAccessor || func.kind === SyntaxKind.SetAccessor) { + error(node, Diagnostics.get_and_set_accessors_cannot_declare_this_parameters); + } + } + + // Only check rest parameter type if it's not a binding pattern. Since binding patterns are + // not allowed in a rest parameter, we already have an error from checkGrammarParameterList. + if (node.dotDotDotToken && !isBindingPattern(node.name) && !isTypeAssignableTo(getReducedType(getTypeOfSymbol(node.symbol)), anyReadonlyArrayType)) { + error(node, Diagnostics.A_rest_parameter_must_be_of_an_array_type); + } + } + + function checkTypePredicate(node: TypePredicateNode): void { + const parent = getTypePredicateParent(node); + if (!parent) { + // The parent must not be valid. + error(node, Diagnostics.A_type_predicate_is_only_allowed_in_return_type_position_for_functions_and_methods); + return; + } + + const signature = getSignatureFromDeclaration(parent); + const typePredicate = getTypePredicateOfSignature(signature); + if (!typePredicate) { + return; + } + + checkSourceElement(node.type); + + const { parameterName } = node; + if (typePredicate.kind === TypePredicateKind.This || typePredicate.kind === TypePredicateKind.AssertsThis) { + getTypeFromThisTypeNode(parameterName as ThisTypeNode); + } + else { + if (typePredicate.parameterIndex >= 0) { + if (signatureHasRestParameter(signature) && typePredicate.parameterIndex === signature.parameters.length - 1) { + error(parameterName, Diagnostics.A_type_predicate_cannot_reference_a_rest_parameter); + } + else { + if (typePredicate.type) { + const leadingError = () => chainDiagnosticMessages(/*details*/ undefined, Diagnostics.A_type_predicate_s_type_must_be_assignable_to_its_parameter_s_type); + checkTypeAssignableTo(typePredicate.type, getTypeOfSymbol(signature.parameters[typePredicate.parameterIndex]), node.type, /*headMessage*/ undefined, leadingError); + } + } + } + else if (parameterName) { + let hasReportedError = false; + for (const { name } of parent.parameters) { + if ( + isBindingPattern(name) && + checkIfTypePredicateVariableIsDeclaredInBindingPattern(name, parameterName, typePredicate.parameterName) + ) { + hasReportedError = true; + break; + } + } + if (!hasReportedError) { + error(node.parameterName, Diagnostics.Cannot_find_parameter_0, typePredicate.parameterName); + } + } + } + } + + function getTypePredicateParent(node: Node): SignatureDeclaration | undefined { + switch (node.parent.kind) { + case SyntaxKind.ArrowFunction: + case SyntaxKind.CallSignature: + case SyntaxKind.FunctionDeclaration: + case SyntaxKind.FunctionExpression: + case SyntaxKind.FunctionType: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + const parent = node.parent as SignatureDeclaration; + if (node === parent.type) { + return parent; + } + } + } + + function checkIfTypePredicateVariableIsDeclaredInBindingPattern( + pattern: BindingPattern, + predicateVariableNode: Node, + predicateVariableName: string, + ) { + for (const element of pattern.elements) { + if (isOmittedExpression(element)) { + continue; + } + + const name = element.name; + if (name.kind === SyntaxKind.Identifier && name.escapedText === predicateVariableName) { + error(predicateVariableNode, Diagnostics.A_type_predicate_cannot_reference_element_0_in_a_binding_pattern, predicateVariableName); + return true; + } + else if (name.kind === SyntaxKind.ArrayBindingPattern || name.kind === SyntaxKind.ObjectBindingPattern) { + if ( + checkIfTypePredicateVariableIsDeclaredInBindingPattern( + name, + predicateVariableNode, + predicateVariableName, + ) + ) { + return true; + } + } + } + } + + function checkSignatureDeclaration(node: SignatureDeclaration) { + // Grammar checking + if (node.kind === SyntaxKind.IndexSignature) { + checkGrammarIndexSignature(node); + } + // TODO (yuisu): Remove this check in else-if when SyntaxKind.Construct is moved and ambient context is handled + else if ( + node.kind === SyntaxKind.FunctionType || node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.ConstructorType || + node.kind === SyntaxKind.CallSignature || node.kind === SyntaxKind.Constructor || + node.kind === SyntaxKind.ConstructSignature + ) { + checkGrammarFunctionLikeDeclaration(node as FunctionLikeDeclaration); + } + + const functionFlags = getFunctionFlags(node as FunctionLikeDeclaration); + if (!(functionFlags & FunctionFlags.Invalid)) { + // Async generators prior to ES2018 require the __await and __asyncGenerator helpers + if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.AsyncGenerator && languageVersion < LanguageFeatureMinimumTarget.AsyncGenerators) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.AsyncGeneratorIncludes); + } + + // Async functions prior to ES2017 require the __awaiter helper + if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async && languageVersion < LanguageFeatureMinimumTarget.AsyncFunctions) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Awaiter); + } + + // Generator functions, Async functions, and Async Generator functions prior to + // ES2015 require the __generator helper + if ((functionFlags & FunctionFlags.AsyncGenerator) !== FunctionFlags.Normal && languageVersion < LanguageFeatureMinimumTarget.Generators) { + checkExternalEmitHelpers(node, ExternalEmitHelpers.Generator); + } + } + + checkTypeParameters(getEffectiveTypeParameterDeclarations(node)); + checkUnmatchedJSDocParameters(node); + + forEach(node.parameters, checkParameter); + + // TODO(rbuckton): Should we start checking JSDoc types? + if (node.type) { + checkSourceElement(node.type); + } + + addLazyDiagnostic(checkSignatureDeclarationDiagnostics); + + function checkSignatureDeclarationDiagnostics() { + checkCollisionWithArgumentsInGeneratedCode(node); + + let returnTypeNode = getEffectiveReturnTypeNode(node); + let returnTypeErrorLocation = returnTypeNode; + + if (isInJSFile(node)) { + const typeTag = getJSDocTypeTag(node); + if (typeTag && typeTag.typeExpression && isTypeReferenceNode(typeTag.typeExpression.type)) { + const signature = getSingleCallSignature(getTypeFromTypeNode(typeTag.typeExpression)); + if (signature && signature.declaration) { + returnTypeNode = getEffectiveReturnTypeNode(signature.declaration); + returnTypeErrorLocation = typeTag.typeExpression.type; + } + } + } + + if (noImplicitAny && !returnTypeNode) { + switch (node.kind) { + case SyntaxKind.ConstructSignature: + error(node, Diagnostics.Construct_signature_which_lacks_return_type_annotation_implicitly_has_an_any_return_type); + break; + case SyntaxKind.CallSignature: + error(node, Diagnostics.Call_signature_which_lacks_return_type_annotation_implicitly_has_an_any_return_type); + break; + } + } + + if (returnTypeNode && returnTypeErrorLocation) { + const functionFlags = getFunctionFlags(node as FunctionDeclaration); + if ((functionFlags & (FunctionFlags.Invalid | FunctionFlags.Generator)) === FunctionFlags.Generator) { + const returnType = getTypeFromTypeNode(returnTypeNode); + if (returnType === voidType) { + error(returnTypeErrorLocation, Diagnostics.A_generator_cannot_have_a_void_type_annotation); + } + else { + checkGeneratorInstantiationAssignabilityToReturnType(returnType, functionFlags, returnTypeErrorLocation); + } + } + else if ((functionFlags & FunctionFlags.AsyncGenerator) === FunctionFlags.Async) { + checkAsyncFunctionReturnType(node as FunctionLikeDeclaration, returnTypeNode, returnTypeErrorLocation); + } + } + if (node.kind !== SyntaxKind.IndexSignature && node.kind !== SyntaxKind.JSDocFunctionType) { + registerForUnusedIdentifiersCheck(node); + } + } + } + + function checkGeneratorInstantiationAssignabilityToReturnType(returnType: Type, functionFlags: FunctionFlags, errorNode?: TypeNode) { + // Naively, one could check that Generator is assignable to the return type annotation. + // However, that would not catch the error in the following case. + // + // interface BadGenerator extends Iterable, Iterator { } + // function* g(): BadGenerator { } // Iterable and Iterator have different types! + // + const generatorYieldType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Yield, returnType, (functionFlags & FunctionFlags.Async) !== 0) || anyType; + const generatorReturnType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Return, returnType, (functionFlags & FunctionFlags.Async) !== 0) || generatorYieldType; + const generatorNextType = getIterationTypeOfGeneratorFunctionReturnType(IterationTypeKind.Next, returnType, (functionFlags & FunctionFlags.Async) !== 0) || unknownType; + const generatorInstantiation = createGeneratorType(generatorYieldType, generatorReturnType, generatorNextType, !!(functionFlags & FunctionFlags.Async)); + + return checkTypeAssignableTo(generatorInstantiation, returnType, errorNode); + } + + function checkClassForDuplicateDeclarations(node: ClassLikeDeclaration) { + const instanceNames = new Map<__String, DeclarationMeaning>(); + const staticNames = new Map<__String, DeclarationMeaning>(); + // instance and static private identifiers share the same scope + const privateIdentifiers = new Map<__String, DeclarationMeaning>(); + for (const member of node.members) { + if (member.kind === SyntaxKind.Constructor) { + for (const param of (member as ConstructorDeclaration).parameters) { + if (isParameterPropertyDeclaration(param, member) && !isBindingPattern(param.name)) { + addName(instanceNames, param.name, param.name.escapedText, DeclarationMeaning.GetOrSetAccessor); + } + } + } + else { + const isStaticMember = isStatic(member); + const name = member.name; + if (!name) { + continue; + } + const isPrivate = isPrivateIdentifier(name); + const privateStaticFlags = isPrivate && isStaticMember ? DeclarationMeaning.PrivateStatic : 0; + const names = isPrivate ? privateIdentifiers : + isStaticMember ? staticNames : + instanceNames; + + const memberName = name && getEffectivePropertyNameForPropertyNameNode(name); + if (memberName) { + switch (member.kind) { + case SyntaxKind.GetAccessor: + addName(names, name, memberName, DeclarationMeaning.GetAccessor | privateStaticFlags); + break; + + case SyntaxKind.SetAccessor: + addName(names, name, memberName, DeclarationMeaning.SetAccessor | privateStaticFlags); + break; + + case SyntaxKind.PropertyDeclaration: + addName(names, name, memberName, DeclarationMeaning.GetOrSetAccessor | privateStaticFlags); + break; + + case SyntaxKind.MethodDeclaration: + addName(names, name, memberName, DeclarationMeaning.Method | privateStaticFlags); + break; + } + } + } + } + + function addName(names: Map<__String, DeclarationMeaning>, location: Node, name: __String, meaning: DeclarationMeaning) { + const prev = names.get(name); + if (prev) { + // For private identifiers, do not allow mixing of static and instance members with the same name + if ((prev & DeclarationMeaning.PrivateStatic) !== (meaning & DeclarationMeaning.PrivateStatic)) { + error(location, Diagnostics.Duplicate_identifier_0_Static_and_instance_elements_cannot_share_the_same_private_name, getTextOfNode(location)); + } + else { + const prevIsMethod = !!(prev & DeclarationMeaning.Method); + const isMethod = !!(meaning & DeclarationMeaning.Method); + if (prevIsMethod || isMethod) { + if (prevIsMethod !== isMethod) { + error(location, Diagnostics.Duplicate_identifier_0, getTextOfNode(location)); + } + // If this is a method/method duplication is might be an overload, so this will be handled when overloads are considered + } + else if (prev & meaning & ~DeclarationMeaning.PrivateStatic) { + error(location, Diagnostics.Duplicate_identifier_0, getTextOfNode(location)); + } + else { + names.set(name, prev | meaning); + } + } + } + else { + names.set(name, meaning); + } + } + } + + /** + * Static members being set on a constructor function may conflict with built-in properties + * of Function. Esp. in ECMAScript 5 there are non-configurable and non-writable + * built-in properties. This check issues a transpile error when a class has a static + * member with the same name as a non-writable built-in property. + * + * @see http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.3 + * @see http://www.ecma-international.org/ecma-262/5.1/#sec-15.3.5 + * @see http://www.ecma-international.org/ecma-262/6.0/#sec-properties-of-the-function-constructor + * @see http://www.ecma-international.org/ecma-262/6.0/#sec-function-instances + */ + function checkClassForStaticPropertyNameConflicts(node: ClassLikeDeclaration) { + for (const member of node.members) { + const memberNameNode = member.name; + const isStaticMember = isStatic(member); + if (isStaticMember && memberNameNode) { + const memberName = getEffectivePropertyNameForPropertyNameNode(memberNameNode); + switch (memberName) { + case "name": + case "length": + case "caller": + case "arguments": + if (useDefineForClassFields) { + break; + } + // fall through + case "prototype": + const message = Diagnostics.Static_property_0_conflicts_with_built_in_property_Function_0_of_constructor_function_1; + const className = getNameOfSymbolAsWritten(getSymbolOfDeclaration(node)); + error(memberNameNode, message, memberName, className); + break; + } + } + } + } + + function checkObjectTypeForDuplicateDeclarations(node: TypeLiteralNode | InterfaceDeclaration) { + const names = new Map(); + for (const member of node.members) { + if (member.kind === SyntaxKind.PropertySignature) { + let memberName: string; + const name = member.name!; + switch (name.kind) { + case SyntaxKind.StringLiteral: + case SyntaxKind.NumericLiteral: + memberName = name.text; + break; + case SyntaxKind.Identifier: + memberName = idText(name); + break; + default: + continue; + } + + if (names.get(memberName)) { + error(getNameOfDeclaration(member.symbol.valueDeclaration), Diagnostics.Duplicate_identifier_0, memberName); + error(member.name, Diagnostics.Duplicate_identifier_0, memberName); + } + else { + names.set(memberName, true); + } + } + } + } + + function checkTypeForDuplicateIndexSignatures(node: ClassLikeDeclaration | InterfaceDeclaration | TypeLiteralNode) { + if (node.kind === SyntaxKind.InterfaceDeclaration) { + const nodeSymbol = getSymbolOfDeclaration(node); + // in case of merging interface declaration it is possible that we'll enter this check procedure several times for every declaration + // to prevent this run check only for the first declaration of a given kind + if (nodeSymbol.declarations && nodeSymbol.declarations.length > 0 && nodeSymbol.declarations[0] !== node) { + return; + } + } + + // TypeScript 1.0 spec (April 2014) + // 3.7.4: An object type can contain at most one string index signature and one numeric index signature. + // 8.5: A class declaration can have at most one string index member declaration and one numeric index member declaration + const indexSymbol = getIndexSymbol(getSymbolOfDeclaration(node)); + if (indexSymbol?.declarations) { + const indexSignatureMap = new Map(); + for (const declaration of (indexSymbol.declarations as IndexSignatureDeclaration[])) { + if (declaration.parameters.length === 1 && declaration.parameters[0].type) { + forEachType(getTypeFromTypeNode(declaration.parameters[0].type), type => { + const entry = indexSignatureMap.get(getTypeId(type)); + if (entry) { + entry.declarations.push(declaration); + } + else { + indexSignatureMap.set(getTypeId(type), { type, declarations: [declaration] }); + } + }); + } + } + indexSignatureMap.forEach(entry => { + if (entry.declarations.length > 1) { + for (const declaration of entry.declarations) { + error(declaration, Diagnostics.Duplicate_index_signature_for_type_0, typeToString(entry.type)); + } + } + }); + } + } + + function checkPropertyDeclaration(node: PropertyDeclaration | PropertySignature) { + // Grammar checking + if (!checkGrammarModifiers(node) && !checkGrammarProperty(node)) checkGrammarComputedPropertyName(node.name); + checkVariableLikeDeclaration(node); + + setNodeLinksForPrivateIdentifierScope(node); + + // property signatures already report "initializer not allowed in ambient context" elsewhere + if (hasSyntacticModifier(node, ModifierFlags.Abstract) && node.kind === SyntaxKind.PropertyDeclaration && node.initializer) { + error(node, Diagnostics.Property_0_cannot_have_an_initializer_because_it_is_marked_abstract, declarationNameToString(node.name)); + } + } + + function checkPropertySignature(node: PropertySignature) { + if (isPrivateIdentifier(node.name)) { + error(node, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + return checkPropertyDeclaration(node); + } + + function checkMethodDeclaration(node: MethodDeclaration | MethodSignature) { + // Grammar checking + if (!checkGrammarMethod(node)) checkGrammarComputedPropertyName(node.name); + + if (isMethodDeclaration(node) && node.asteriskToken && isIdentifier(node.name) && idText(node.name) === "constructor") { + error(node.name, Diagnostics.Class_constructor_may_not_be_a_generator); + } + + // Grammar checking for modifiers is done inside the function checkGrammarFunctionLikeDeclaration + checkFunctionOrMethodDeclaration(node); + + // method signatures already report "implementation not allowed in ambient context" elsewhere + if (hasSyntacticModifier(node, ModifierFlags.Abstract) && node.kind === SyntaxKind.MethodDeclaration && node.body) { + error(node, Diagnostics.Method_0_cannot_have_an_implementation_because_it_is_marked_abstract, declarationNameToString(node.name)); + } + + // Private named methods are only allowed in class declarations + if (isPrivateIdentifier(node.name) && !getContainingClass(node)) { + error(node, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies); + } + + setNodeLinksForPrivateIdentifierScope(node); + } + + function setNodeLinksForPrivateIdentifierScope(node: PropertyDeclaration | PropertySignature | MethodDeclaration | MethodSignature | AccessorDeclaration) { + if (isPrivateIdentifier(node.name)) { + if ( + languageVersion < LanguageFeatureMinimumTarget.PrivateNamesAndClassStaticBlocks || + languageVersion < LanguageFeatureMinimumTarget.ClassAndClassElementDecorators || + !useDefineForClassFields + ) { + for (let lexicalScope = getEnclosingBlockScopeContainer(node); !!lexicalScope; lexicalScope = getEnclosingBlockScopeContainer(lexicalScope)) { + getNodeLinks(lexicalScope).flags |= NodeCheckFlags.ContainsClassWithPrivateIdentifiers; + } + + // If this is a private element in a class expression inside the body of a loop, + // then we must use a block-scoped binding to store the additional variables required + // to transform private elements. + if (isClassExpression(node.parent)) { + const enclosingIterationStatement = getEnclosingIterationStatement(node.parent); + if (enclosingIterationStatement) { + getNodeLinks(node.name).flags |= NodeCheckFlags.BlockScopedBindingInLoop; + getNodeLinks(enclosingIterationStatement).flags |= NodeCheckFlags.LoopWithCapturedBlockScopedBinding; + } + } + } + } + } + + function checkClassStaticBlockDeclaration(node: ClassStaticBlockDeclaration) { + checkGrammarModifiers(node); + + forEachChild(node, checkSourceElement); + } + + function checkConstructorDeclaration(node: ConstructorDeclaration) { + // Grammar check on signature of constructor and modifier of the constructor is done in checkSignatureDeclaration function. + checkSignatureDeclaration(node); + // Grammar check for checking only related to constructorDeclaration + if (!checkGrammarConstructorTypeParameters(node)) checkGrammarConstructorTypeAnnotation(node); + + checkSourceElement(node.body); + + const symbol = getSymbolOfDeclaration(node); + const firstDeclaration = getDeclarationOfKind(symbol, node.kind); + + // Only type check the symbol once + if (node === firstDeclaration) { + checkFunctionOrConstructorSymbol(symbol); + } + + // exit early in the case of signature - super checks are not relevant to them + if (nodeIsMissing(node.body)) { + return; + } + + addLazyDiagnostic(checkConstructorDeclarationDiagnostics); + + return; + + function isInstancePropertyWithInitializerOrPrivateIdentifierProperty(n: Node): boolean { + if (isPrivateIdentifierClassElementDeclaration(n)) { + return true; + } + return n.kind === SyntaxKind.PropertyDeclaration && + !isStatic(n) && + !!(n as PropertyDeclaration).initializer; + } + + function checkConstructorDeclarationDiagnostics() { + // TS 1.0 spec (April 2014): 8.3.2 + // Constructors of classes with no extends clause may not contain super calls, whereas + // constructors of derived classes must contain at least one super call somewhere in their function body. + const containingClassDecl = node.parent; + if (getClassExtendsHeritageElement(containingClassDecl)) { + captureLexicalThis(node.parent, containingClassDecl); + const classExtendsNull = classDeclarationExtendsNull(containingClassDecl); + const superCall = findFirstSuperCall(node.body!); + if (superCall) { + if (classExtendsNull) { + error(superCall, Diagnostics.A_constructor_cannot_contain_a_super_call_when_its_class_extends_null); + } + + // A super call must be root-level in a constructor if both of the following are true: + // - The containing class is a derived class. + // - The constructor declares parameter properties + // or the containing class declares instance member variables with initializers. + + const superCallShouldBeRootLevel = !emitStandardClassFields && + (some(node.parent.members, isInstancePropertyWithInitializerOrPrivateIdentifierProperty) || + some(node.parameters, p => hasSyntacticModifier(p, ModifierFlags.ParameterPropertyModifier))); + + if (superCallShouldBeRootLevel) { + // Until we have better flow analysis, it is an error to place the super call within any kind of block or conditional + // See GH #8277 + if (!superCallIsRootLevelInConstructor(superCall, node.body!)) { + error(superCall, Diagnostics.A_super_call_must_be_a_root_level_statement_within_a_constructor_of_a_derived_class_that_contains_initialized_properties_parameter_properties_or_private_identifiers); + } + // Skip past any prologue directives to check statements for referring to 'super' or 'this' before a super call + else { + let superCallStatement: ExpressionStatement | undefined; + + for (const statement of node.body!.statements) { + if (isExpressionStatement(statement) && isSuperCall(skipOuterExpressions(statement.expression))) { + superCallStatement = statement; + break; + } + if (nodeImmediatelyReferencesSuperOrThis(statement)) { + break; + } + } + + // Until we have better flow analysis, it is an error to place the super call within any kind of block or conditional + // See GH #8277 + if (superCallStatement === undefined) { + error(node, Diagnostics.A_super_call_must_be_the_first_statement_in_the_constructor_to_refer_to_super_or_this_when_a_derived_class_contains_initialized_properties_parameter_properties_or_private_identifiers); + } + } + } + } + else if (!classExtendsNull) { + error(node, Diagnostics.Constructors_for_derived_classes_must_contain_a_super_call); + } + } + } + } + + function superCallIsRootLevelInConstructor(superCall: Node, body: Block) { + const superCallParent = walkUpParenthesizedExpressions(superCall.parent); + return isExpressionStatement(superCallParent) && superCallParent.parent === body; + } + + function nodeImmediatelyReferencesSuperOrThis(node: Node): boolean { + if (node.kind === SyntaxKind.SuperKeyword || node.kind === SyntaxKind.ThisKeyword) { + return true; + } + + if (isThisContainerOrFunctionBlock(node)) { + return false; + } + + return !!forEachChild(node, nodeImmediatelyReferencesSuperOrThis); + } + + function checkAccessorDeclaration(node: AccessorDeclaration) { + if (isIdentifier(node.name) && idText(node.name) === "constructor" && isClassLike(node.parent)) { + error(node.name, Diagnostics.Class_constructor_may_not_be_an_accessor); + } + addLazyDiagnostic(checkAccessorDeclarationDiagnostics); + checkSourceElement(node.body); + setNodeLinksForPrivateIdentifierScope(node); + + function checkAccessorDeclarationDiagnostics() { + // Grammar checking accessors + if (!checkGrammarFunctionLikeDeclaration(node) && !checkGrammarAccessor(node)) checkGrammarComputedPropertyName(node.name); + + checkDecorators(node); + checkSignatureDeclaration(node); + if (node.kind === SyntaxKind.GetAccessor) { + if (!(node.flags & NodeFlags.Ambient) && nodeIsPresent(node.body) && (node.flags & NodeFlags.HasImplicitReturn)) { + if (!(node.flags & NodeFlags.HasExplicitReturn)) { + error(node.name, Diagnostics.A_get_accessor_must_return_a_value); + } + } + } + // Do not use hasDynamicName here, because that returns false for well known symbols. + // We want to perform checkComputedPropertyName for all computed properties, including + // well known symbols. + if (node.name.kind === SyntaxKind.ComputedPropertyName) { + checkComputedPropertyName(node.name); + } + + if (hasBindableName(node)) { + // TypeScript 1.0 spec (April 2014): 8.4.3 + // Accessors for the same member name must specify the same accessibility. + const symbol = getSymbolOfDeclaration(node); + const getter = getDeclarationOfKind(symbol, SyntaxKind.GetAccessor); + const setter = getDeclarationOfKind(symbol, SyntaxKind.SetAccessor); + if (getter && setter && !(getNodeCheckFlags(getter) & NodeCheckFlags.TypeChecked)) { + getNodeLinks(getter).flags |= NodeCheckFlags.TypeChecked; + const getterFlags = getEffectiveModifierFlags(getter); + const setterFlags = getEffectiveModifierFlags(setter); + if ((getterFlags & ModifierFlags.Abstract) !== (setterFlags & ModifierFlags.Abstract)) { + error(getter.name, Diagnostics.Accessors_must_both_be_abstract_or_non_abstract); + error(setter.name, Diagnostics.Accessors_must_both_be_abstract_or_non_abstract); + } + if ( + ((getterFlags & ModifierFlags.Protected) && !(setterFlags & (ModifierFlags.Protected | ModifierFlags.Private))) || + ((getterFlags & ModifierFlags.Private) && !(setterFlags & ModifierFlags.Private)) + ) { + error(getter.name, Diagnostics.A_get_accessor_must_be_at_least_as_accessible_as_the_setter); + error(setter.name, Diagnostics.A_get_accessor_must_be_at_least_as_accessible_as_the_setter); + } + } + } + const returnType = getTypeOfAccessors(getSymbolOfDeclaration(node)); + if (node.kind === SyntaxKind.GetAccessor) { + checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, returnType); + } + } + } + + function checkMissingDeclaration(node: Node) { + checkDecorators(node); + } + + function getEffectiveTypeArgumentAtIndex(node: TypeReferenceNode | ExpressionWithTypeArguments, typeParameters: readonly TypeParameter[], index: number): Type { + if (node.typeArguments && index < node.typeArguments.length) { + return getTypeFromTypeNode(node.typeArguments[index]); + } + return getEffectiveTypeArguments(node, typeParameters)[index]; + } + + function getEffectiveTypeArguments(node: TypeReferenceNode | ExpressionWithTypeArguments | NodeWithTypeArguments, typeParameters: readonly TypeParameter[]): Type[] { + return fillMissingTypeArguments(map(node.typeArguments!, getTypeFromTypeNode), typeParameters, getMinTypeArgumentCount(typeParameters), isInJSFile(node)); + } + + function checkTypeArgumentConstraints(node: TypeReferenceNode | ExpressionWithTypeArguments | NodeWithTypeArguments, typeParameters: readonly TypeParameter[]): boolean { + let typeArguments: Type[] | undefined; + let mapper: TypeMapper | undefined; + let result = true; + for (let i = 0; i < typeParameters.length; i++) { + const constraint = getConstraintOfTypeParameter(typeParameters[i]); + if (constraint) { + if (!typeArguments) { + typeArguments = getEffectiveTypeArguments(node, typeParameters); + mapper = createTypeMapper(typeParameters, typeArguments); + } + result = result && checkTypeAssignableTo( + typeArguments[i], + instantiateType(constraint, mapper), + node.typeArguments![i], + Diagnostics.Type_0_does_not_satisfy_the_constraint_1, + ); + } + } + return result; + } + + function getTypeParametersForTypeAndSymbol(type: Type, symbol: Symbol) { + if (!isErrorType(type)) { + return symbol.flags & SymbolFlags.TypeAlias && getSymbolLinks(symbol).typeParameters || + (getObjectFlags(type) & ObjectFlags.Reference ? (type as TypeReference).target.localTypeParameters : undefined); + } + return undefined; + } + + function getTypeParametersForTypeReferenceOrImport(node: TypeReferenceNode | ExpressionWithTypeArguments | ImportTypeNode) { + const type = getTypeFromTypeNode(node); + if (!isErrorType(type)) { + const symbol = getNodeLinks(node).resolvedSymbol; + if (symbol) { + return getTypeParametersForTypeAndSymbol(type, symbol); + } + } + return undefined; + } + + function checkTypeReferenceNode(node: TypeReferenceNode | ExpressionWithTypeArguments) { + checkGrammarTypeArguments(node, node.typeArguments); + if (node.kind === SyntaxKind.TypeReference && !isInJSFile(node) && !isInJSDoc(node) && node.typeArguments && node.typeName.end !== node.typeArguments.pos) { + // If there was a token between the type name and the type arguments, check if it was a DotToken + const sourceFile = getSourceFileOfNode(node); + if (scanTokenAtPosition(sourceFile, node.typeName.end) === SyntaxKind.DotToken) { + grammarErrorAtPos(node, skipTrivia(sourceFile.text, node.typeName.end), 1, Diagnostics.JSDoc_types_can_only_be_used_inside_documentation_comments); + } + } + forEach(node.typeArguments, checkSourceElement); + checkTypeReferenceOrImport(node); + } + + function checkTypeReferenceOrImport(node: TypeReferenceNode | ExpressionWithTypeArguments | ImportTypeNode) { + const type = getTypeFromTypeNode(node); + if (!isErrorType(type)) { + if (node.typeArguments) { + addLazyDiagnostic(() => { + const typeParameters = getTypeParametersForTypeReferenceOrImport(node); + if (typeParameters) { + checkTypeArgumentConstraints(node, typeParameters); + } + }); + } + const symbol = getNodeLinks(node).resolvedSymbol; + if (symbol) { + if (some(symbol.declarations, d => isTypeDeclaration(d) && !!(d.flags & NodeFlags.Deprecated))) { + addDeprecatedSuggestion( + getDeprecatedSuggestionNode(node), + symbol.declarations!, + symbol.escapedName as string, + ); + } + } + } + } + + function getTypeArgumentConstraint(node: TypeNode): Type | undefined { + const typeReferenceNode = tryCast(node.parent, isTypeReferenceType); + if (!typeReferenceNode) return undefined; + const typeParameters = getTypeParametersForTypeReferenceOrImport(typeReferenceNode); + if (!typeParameters) return undefined; + const constraint = getConstraintOfTypeParameter(typeParameters[typeReferenceNode.typeArguments!.indexOf(node)]); + return constraint && instantiateType(constraint, createTypeMapper(typeParameters, getEffectiveTypeArguments(typeReferenceNode, typeParameters))); + } + + function checkTypeQuery(node: TypeQueryNode) { + getTypeFromTypeQueryNode(node); + } + + function checkTypeLiteral(node: TypeLiteralNode) { + forEach(node.members, checkSourceElement); + addLazyDiagnostic(checkTypeLiteralDiagnostics); + + function checkTypeLiteralDiagnostics() { + const type = getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node); + checkIndexConstraints(type, type.symbol); + checkTypeForDuplicateIndexSignatures(node); + checkObjectTypeForDuplicateDeclarations(node); + } + } + + function checkArrayType(node: ArrayTypeNode) { + checkSourceElement(node.elementType); + } + + function checkTupleType(node: TupleTypeNode) { + let seenOptionalElement = false; + let seenRestElement = false; + for (const e of node.elements) { + let flags = getTupleElementFlags(e); + if (flags & ElementFlags.Variadic) { + const type = getTypeFromTypeNode((e as RestTypeNode | NamedTupleMember).type); + if (!isArrayLikeType(type)) { + error(e, Diagnostics.A_rest_element_type_must_be_an_array_type); + break; + } + if (isArrayType(type) || isTupleType(type) && type.target.combinedFlags & ElementFlags.Rest) { + flags |= ElementFlags.Rest; + } + } + if (flags & ElementFlags.Rest) { + if (seenRestElement) { + grammarErrorOnNode(e, Diagnostics.A_rest_element_cannot_follow_another_rest_element); + break; + } + seenRestElement = true; + } + else if (flags & ElementFlags.Optional) { + if (seenRestElement) { + grammarErrorOnNode(e, Diagnostics.An_optional_element_cannot_follow_a_rest_element); + break; + } + seenOptionalElement = true; + } + else if (flags & ElementFlags.Required && seenOptionalElement) { + grammarErrorOnNode(e, Diagnostics.A_required_element_cannot_follow_an_optional_element); + break; + } + } + forEach(node.elements, checkSourceElement); + getTypeFromTypeNode(node); + } + + function checkUnionOrIntersectionType(node: UnionOrIntersectionTypeNode) { + forEach(node.types, checkSourceElement); + getTypeFromTypeNode(node); + } + + function checkIndexedAccessIndexType(type: Type, accessNode: IndexedAccessTypeNode | ElementAccessExpression) { + if (!(type.flags & TypeFlags.IndexedAccess)) { + return type; + } + // Check if the index type is assignable to 'keyof T' for the object type. + const objectType = (type as IndexedAccessType).objectType; + const indexType = (type as IndexedAccessType).indexType; + // skip index type deferral on remapping mapped types + const objectIndexType = isGenericMappedType(objectType) && getMappedTypeNameTypeKind(objectType) === MappedTypeNameTypeKind.Remapping + ? getIndexTypeForMappedType(objectType, IndexFlags.None) + : getIndexType(objectType, IndexFlags.None); + const hasNumberIndexInfo = !!getIndexInfoOfType(objectType, numberType); + if (everyType(indexType, t => isTypeAssignableTo(t, objectIndexType) || hasNumberIndexInfo && isApplicableIndexType(t, numberType))) { + if ( + accessNode.kind === SyntaxKind.ElementAccessExpression && isAssignmentTarget(accessNode) && + getObjectFlags(objectType) & ObjectFlags.Mapped && getMappedTypeModifiers(objectType as MappedType) & MappedTypeModifiers.IncludeReadonly + ) { + error(accessNode, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType)); + } + return type; + } + if (isGenericObjectType(objectType)) { + const propertyName = getPropertyNameFromIndex(indexType, accessNode); + if (propertyName) { + const propertySymbol = forEachType(getApparentType(objectType), t => getPropertyOfType(t, propertyName)); + if (propertySymbol && getDeclarationModifierFlagsFromSymbol(propertySymbol) & ModifierFlags.NonPublicAccessibilityModifier) { + error(accessNode, Diagnostics.Private_or_protected_member_0_cannot_be_accessed_on_a_type_parameter, unescapeLeadingUnderscores(propertyName)); + return errorType; + } + } + } + error(accessNode, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(objectType)); + return errorType; + } + + function checkIndexedAccessType(node: IndexedAccessTypeNode) { + checkSourceElement(node.objectType); + checkSourceElement(node.indexType); + checkIndexedAccessIndexType(getTypeFromIndexedAccessTypeNode(node), node); + } + + function checkMappedType(node: MappedTypeNode) { + checkGrammarMappedType(node); + checkSourceElement(node.typeParameter); + checkSourceElement(node.nameType); + checkSourceElement(node.type); + + if (!node.type) { + reportImplicitAny(node, anyType); + } + + const type = getTypeFromMappedTypeNode(node) as MappedType; + const nameType = getNameTypeFromMappedType(type); + if (nameType) { + checkTypeAssignableTo(nameType, stringNumberSymbolType, node.nameType); + } + else { + const constraintType = getConstraintTypeFromMappedType(type); + checkTypeAssignableTo(constraintType, stringNumberSymbolType, getEffectiveConstraintOfTypeParameter(node.typeParameter)); + } + } + + function checkGrammarMappedType(node: MappedTypeNode) { + if (node.members?.length) { + return grammarErrorOnNode(node.members[0], Diagnostics.A_mapped_type_may_not_declare_properties_or_methods); + } + } + + function checkThisType(node: ThisTypeNode) { + getTypeFromThisTypeNode(node); + } + + function checkTypeOperator(node: TypeOperatorNode) { + checkGrammarTypeOperatorNode(node); + checkSourceElement(node.type); + } + + function checkConditionalType(node: ConditionalTypeNode) { + forEachChild(node, checkSourceElement); + } + + function checkInferType(node: InferTypeNode) { + if (!findAncestor(node, n => n.parent && n.parent.kind === SyntaxKind.ConditionalType && (n.parent as ConditionalTypeNode).extendsType === n)) { + grammarErrorOnNode(node, Diagnostics.infer_declarations_are_only_permitted_in_the_extends_clause_of_a_conditional_type); + } + checkSourceElement(node.typeParameter); + const symbol = getSymbolOfDeclaration(node.typeParameter); + if (symbol.declarations && symbol.declarations.length > 1) { + const links = getSymbolLinks(symbol); + if (!links.typeParametersChecked) { + links.typeParametersChecked = true; + const typeParameter = getDeclaredTypeOfTypeParameter(symbol); + const declarations: TypeParameterDeclaration[] = getDeclarationsOfKind(symbol, SyntaxKind.TypeParameter); + if (!areTypeParametersIdentical(declarations, [typeParameter], decl => [decl])) { + // Report an error on every conflicting declaration. + const name = symbolToString(symbol); + for (const declaration of declarations) { + error(declaration.name, Diagnostics.All_declarations_of_0_must_have_identical_constraints, name); + } + } + } + } + registerForUnusedIdentifiersCheck(node); + } + + function checkTemplateLiteralType(node: TemplateLiteralTypeNode) { + for (const span of node.templateSpans) { + checkSourceElement(span.type); + const type = getTypeFromTypeNode(span.type); + checkTypeAssignableTo(type, templateConstraintType, span.type); + } + getTypeFromTypeNode(node); + } + + function checkImportType(node: ImportTypeNode) { + checkSourceElement(node.argument); + + if (node.attributes) { + getResolutionModeOverride(node.attributes, grammarErrorOnNode); + } + checkTypeReferenceOrImport(node); + } + + function checkNamedTupleMember(node: NamedTupleMember) { + if (node.dotDotDotToken && node.questionToken) { + grammarErrorOnNode(node, Diagnostics.A_tuple_member_cannot_be_both_optional_and_rest); + } + if (node.type.kind === SyntaxKind.OptionalType) { + grammarErrorOnNode(node.type, Diagnostics.A_labeled_tuple_element_is_declared_as_optional_with_a_question_mark_after_the_name_and_before_the_colon_rather_than_after_the_type); + } + if (node.type.kind === SyntaxKind.RestType) { + grammarErrorOnNode(node.type, Diagnostics.A_labeled_tuple_element_is_declared_as_rest_with_a_before_the_name_rather_than_before_the_type); + } + checkSourceElement(node.type); + getTypeFromTypeNode(node); + } + + function isPrivateWithinAmbient(node: Node): boolean { + return (hasEffectiveModifier(node, ModifierFlags.Private) || isPrivateIdentifierClassElementDeclaration(node)) && !!(node.flags & NodeFlags.Ambient); + } + + function getEffectiveDeclarationFlags(n: Declaration, flagsToCheck: ModifierFlags): ModifierFlags { + let flags = getCombinedModifierFlagsCached(n); + + // children of classes (even ambient classes) should not be marked as ambient or export + // because those flags have no useful semantics there. + if ( + n.parent.kind !== SyntaxKind.InterfaceDeclaration && + n.parent.kind !== SyntaxKind.ClassDeclaration && + n.parent.kind !== SyntaxKind.ClassExpression && + n.flags & NodeFlags.Ambient + ) { + const container = getEnclosingContainer(n); + if ((container && container.flags & NodeFlags.ExportContext) && !(flags & ModifierFlags.Ambient) && !(isModuleBlock(n.parent) && isModuleDeclaration(n.parent.parent) && isGlobalScopeAugmentation(n.parent.parent))) { + // It is nested in an ambient export context, which means it is automatically exported + flags |= ModifierFlags.Export; + } + flags |= ModifierFlags.Ambient; + } + + return flags & flagsToCheck; + } + + function checkFunctionOrConstructorSymbol(symbol: Symbol): void { + addLazyDiagnostic(() => checkFunctionOrConstructorSymbolWorker(symbol)); + } + + function checkFunctionOrConstructorSymbolWorker(symbol: Symbol): void { + function getCanonicalOverload(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined): Declaration { + // Consider the canonical set of flags to be the flags of the bodyDeclaration or the first declaration + // Error on all deviations from this canonical set of flags + // The caveat is that if some overloads are defined in lib.d.ts, we don't want to + // report the errors on those. To achieve this, we will say that the implementation is + // the canonical signature only if it is in the same container as the first overload + const implementationSharesContainerWithFirstOverload = implementation !== undefined && implementation.parent === overloads[0].parent; + return implementationSharesContainerWithFirstOverload ? implementation : overloads[0]; + } + + function checkFlagAgreementBetweenOverloads(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined, flagsToCheck: ModifierFlags, someOverloadFlags: ModifierFlags, allOverloadFlags: ModifierFlags): void { + // Error if some overloads have a flag that is not shared by all overloads. To find the + // deviations, we XOR someOverloadFlags with allOverloadFlags + const someButNotAllOverloadFlags = someOverloadFlags ^ allOverloadFlags; + if (someButNotAllOverloadFlags !== 0) { + const canonicalFlags = getEffectiveDeclarationFlags(getCanonicalOverload(overloads, implementation), flagsToCheck); + forEach(overloads, o => { + const deviation = getEffectiveDeclarationFlags(o, flagsToCheck) ^ canonicalFlags; + if (deviation & ModifierFlags.Export) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_exported_or_non_exported); + } + else if (deviation & ModifierFlags.Ambient) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_ambient_or_non_ambient); + } + else if (deviation & (ModifierFlags.Private | ModifierFlags.Protected)) { + error(getNameOfDeclaration(o) || o, Diagnostics.Overload_signatures_must_all_be_public_private_or_protected); + } + else if (deviation & ModifierFlags.Abstract) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_abstract_or_non_abstract); + } + }); + } + } + + function checkQuestionTokenAgreementBetweenOverloads(overloads: Declaration[], implementation: FunctionLikeDeclaration | undefined, someHaveQuestionToken: boolean, allHaveQuestionToken: boolean): void { + if (someHaveQuestionToken !== allHaveQuestionToken) { + const canonicalHasQuestionToken = hasQuestionToken(getCanonicalOverload(overloads, implementation)); + forEach(overloads, o => { + const deviation = hasQuestionToken(o) !== canonicalHasQuestionToken; + if (deviation) { + error(getNameOfDeclaration(o), Diagnostics.Overload_signatures_must_all_be_optional_or_required); + } + }); + } + } + + const flagsToCheck: ModifierFlags = ModifierFlags.Export | ModifierFlags.Ambient | ModifierFlags.Private | ModifierFlags.Protected | ModifierFlags.Abstract; + let someNodeFlags: ModifierFlags = ModifierFlags.None; + let allNodeFlags = flagsToCheck; + let someHaveQuestionToken = false; + let allHaveQuestionToken = true; + let hasOverloads = false; + let bodyDeclaration: FunctionLikeDeclaration | undefined; + let lastSeenNonAmbientDeclaration: FunctionLikeDeclaration | undefined; + let previousDeclaration: SignatureDeclaration | undefined; + + const declarations = symbol.declarations; + const isConstructor = (symbol.flags & SymbolFlags.Constructor) !== 0; + + function reportImplementationExpectedError(node: SignatureDeclaration): void { + if (node.name && nodeIsMissing(node.name)) { + return; + } + + let seen = false; + const subsequentNode = forEachChild(node.parent, c => { + if (seen) { + return c; + } + else { + seen = c === node; + } + }); + // We may be here because of some extra nodes between overloads that could not be parsed into a valid node. + // In this case the subsequent node is not really consecutive (.pos !== node.end), and we must ignore it here. + if (subsequentNode && subsequentNode.pos === node.end) { + if (subsequentNode.kind === node.kind) { + const errorNode: Node = (subsequentNode as FunctionLikeDeclaration).name || subsequentNode; + const subsequentName = (subsequentNode as FunctionLikeDeclaration).name; + if ( + node.name && subsequentName && ( + // both are private identifiers + isPrivateIdentifier(node.name) && isPrivateIdentifier(subsequentName) && node.name.escapedText === subsequentName.escapedText || + // Both are computed property names + isComputedPropertyName(node.name) && isComputedPropertyName(subsequentName) && isTypeIdenticalTo(checkComputedPropertyName(node.name), checkComputedPropertyName(subsequentName)) || + // Both are literal property names that are the same. + isPropertyNameLiteral(node.name) && isPropertyNameLiteral(subsequentName) && + getEscapedTextOfIdentifierOrLiteral(node.name) === getEscapedTextOfIdentifierOrLiteral(subsequentName) + ) + ) { + const reportError = (node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature) && + isStatic(node) !== isStatic(subsequentNode); + // we can get here in two cases + // 1. mixed static and instance class members + // 2. something with the same name was defined before the set of overloads that prevents them from merging + // here we'll report error only for the first case since for second we should already report error in binder + if (reportError) { + const diagnostic = isStatic(node) ? Diagnostics.Function_overload_must_be_static : Diagnostics.Function_overload_must_not_be_static; + error(errorNode, diagnostic); + } + return; + } + if (nodeIsPresent((subsequentNode as FunctionLikeDeclaration).body)) { + error(errorNode, Diagnostics.Function_implementation_name_must_be_0, declarationNameToString(node.name)); + return; + } + } + } + const errorNode: Node = node.name || node; + if (isConstructor) { + error(errorNode, Diagnostics.Constructor_implementation_is_missing); + } + else { + // Report different errors regarding non-consecutive blocks of declarations depending on whether + // the node in question is abstract. + if (hasSyntacticModifier(node, ModifierFlags.Abstract)) { + error(errorNode, Diagnostics.All_declarations_of_an_abstract_method_must_be_consecutive); + } + else { + error(errorNode, Diagnostics.Function_implementation_is_missing_or_not_immediately_following_the_declaration); + } + } + } + + let duplicateFunctionDeclaration = false; + let multipleConstructorImplementation = false; + let hasNonAmbientClass = false; + const functionDeclarations = [] as Declaration[]; + if (declarations) { + for (const current of declarations) { + const node = current as SignatureDeclaration | ClassDeclaration | ClassExpression; + const inAmbientContext = node.flags & NodeFlags.Ambient; + const inAmbientContextOrInterface = node.parent && (node.parent.kind === SyntaxKind.InterfaceDeclaration || node.parent.kind === SyntaxKind.TypeLiteral) || inAmbientContext; + if (inAmbientContextOrInterface) { + // check if declarations are consecutive only if they are non-ambient + // 1. ambient declarations can be interleaved + // i.e. this is legal + // declare function foo(); + // declare function bar(); + // declare function foo(); + // 2. mixing ambient and non-ambient declarations is a separate error that will be reported - do not want to report an extra one + previousDeclaration = undefined; + } + + if ((node.kind === SyntaxKind.ClassDeclaration || node.kind === SyntaxKind.ClassExpression) && !inAmbientContext) { + hasNonAmbientClass = true; + } + + if (node.kind === SyntaxKind.FunctionDeclaration || node.kind === SyntaxKind.MethodDeclaration || node.kind === SyntaxKind.MethodSignature || node.kind === SyntaxKind.Constructor) { + functionDeclarations.push(node); + const currentNodeFlags = getEffectiveDeclarationFlags(node, flagsToCheck); + someNodeFlags |= currentNodeFlags; + allNodeFlags &= currentNodeFlags; + someHaveQuestionToken = someHaveQuestionToken || hasQuestionToken(node); + allHaveQuestionToken = allHaveQuestionToken && hasQuestionToken(node); + const bodyIsPresent = nodeIsPresent((node as FunctionLikeDeclaration).body); + + if (bodyIsPresent && bodyDeclaration) { + if (isConstructor) { + multipleConstructorImplementation = true; + } + else { + duplicateFunctionDeclaration = true; + } + } + else if (previousDeclaration?.parent === node.parent && previousDeclaration.end !== node.pos) { + reportImplementationExpectedError(previousDeclaration); + } + + if (bodyIsPresent) { + if (!bodyDeclaration) { + bodyDeclaration = node as FunctionLikeDeclaration; + } + } + else { + hasOverloads = true; + } + + previousDeclaration = node; + + if (!inAmbientContextOrInterface) { + lastSeenNonAmbientDeclaration = node as FunctionLikeDeclaration; + } + } + if (isInJSFile(current) && isFunctionLike(current) && current.jsDoc) { + hasOverloads = length(getJSDocOverloadTags(current)) > 0; + } + } + } + + if (multipleConstructorImplementation) { + forEach(functionDeclarations, declaration => { + error(declaration, Diagnostics.Multiple_constructor_implementations_are_not_allowed); + }); + } + + if (duplicateFunctionDeclaration) { + forEach(functionDeclarations, declaration => { + error(getNameOfDeclaration(declaration) || declaration, Diagnostics.Duplicate_function_implementation); + }); + } + + if (hasNonAmbientClass && !isConstructor && symbol.flags & SymbolFlags.Function && declarations) { + const relatedDiagnostics = filter(declarations, d => d.kind === SyntaxKind.ClassDeclaration) + .map(d => createDiagnosticForNode(d, Diagnostics.Consider_adding_a_declare_modifier_to_this_class)); + + forEach(declarations, declaration => { + const diagnostic = declaration.kind === SyntaxKind.ClassDeclaration + ? Diagnostics.Class_declaration_cannot_implement_overload_list_for_0 + : declaration.kind === SyntaxKind.FunctionDeclaration + ? Diagnostics.Function_with_bodies_can_only_merge_with_classes_that_are_ambient + : undefined; + if (diagnostic) { + addRelatedInfo( + error(getNameOfDeclaration(declaration) || declaration, diagnostic, symbolName(symbol)), + ...relatedDiagnostics, + ); + } + }); + } + + // Abstract methods can't have an implementation -- in particular, they don't need one. + if ( + lastSeenNonAmbientDeclaration && !lastSeenNonAmbientDeclaration.body && + !hasSyntacticModifier(lastSeenNonAmbientDeclaration, ModifierFlags.Abstract) && !lastSeenNonAmbientDeclaration.questionToken + ) { + reportImplementationExpectedError(lastSeenNonAmbientDeclaration); + } + + if (hasOverloads) { + if (declarations) { + checkFlagAgreementBetweenOverloads(declarations, bodyDeclaration, flagsToCheck, someNodeFlags, allNodeFlags); + checkQuestionTokenAgreementBetweenOverloads(declarations, bodyDeclaration, someHaveQuestionToken, allHaveQuestionToken); + } + + if (bodyDeclaration) { + const signatures = getSignaturesOfSymbol(symbol); + const bodySignature = getSignatureFromDeclaration(bodyDeclaration); + for (const signature of signatures) { + if (!isImplementationCompatibleWithOverload(bodySignature, signature)) { + const errorNode = signature.declaration && isJSDocSignature(signature.declaration) + ? (signature.declaration.parent as JSDocOverloadTag | JSDocCallbackTag).tagName + : signature.declaration; + addRelatedInfo( + error(errorNode, Diagnostics.This_overload_signature_is_not_compatible_with_its_implementation_signature), + createDiagnosticForNode(bodyDeclaration, Diagnostics.The_implementation_signature_is_declared_here), + ); + break; + } + } + } + } + } + + function checkExportsOnMergedDeclarations(node: Declaration): void { + addLazyDiagnostic(() => checkExportsOnMergedDeclarationsWorker(node)); + } + + function checkExportsOnMergedDeclarationsWorker(node: Declaration): void { + // if localSymbol is defined on node then node itself is exported - check is required + let symbol = node.localSymbol; + if (!symbol) { + // local symbol is undefined => this declaration is non-exported. + // however symbol might contain other declarations that are exported + symbol = getSymbolOfDeclaration(node)!; + if (!symbol.exportSymbol) { + // this is a pure local symbol (all declarations are non-exported) - no need to check anything + return; + } + } + + // run the check only for the first declaration in the list + if (getDeclarationOfKind(symbol, node.kind) !== node) { + return; + } + + let exportedDeclarationSpaces = DeclarationSpaces.None; + let nonExportedDeclarationSpaces = DeclarationSpaces.None; + let defaultExportedDeclarationSpaces = DeclarationSpaces.None; + for (const d of symbol.declarations!) { + const declarationSpaces = getDeclarationSpaces(d); + const effectiveDeclarationFlags = getEffectiveDeclarationFlags(d, ModifierFlags.Export | ModifierFlags.Default); + + if (effectiveDeclarationFlags & ModifierFlags.Export) { + if (effectiveDeclarationFlags & ModifierFlags.Default) { + defaultExportedDeclarationSpaces |= declarationSpaces; + } + else { + exportedDeclarationSpaces |= declarationSpaces; + } + } + else { + nonExportedDeclarationSpaces |= declarationSpaces; + } + } + + // Spaces for anything not declared a 'default export'. + const nonDefaultExportedDeclarationSpaces = exportedDeclarationSpaces | nonExportedDeclarationSpaces; + + const commonDeclarationSpacesForExportsAndLocals = exportedDeclarationSpaces & nonExportedDeclarationSpaces; + const commonDeclarationSpacesForDefaultAndNonDefault = defaultExportedDeclarationSpaces & nonDefaultExportedDeclarationSpaces; + + if (commonDeclarationSpacesForExportsAndLocals || commonDeclarationSpacesForDefaultAndNonDefault) { + // declaration spaces for exported and non-exported declarations intersect + for (const d of symbol.declarations!) { + const declarationSpaces = getDeclarationSpaces(d); + + const name = getNameOfDeclaration(d); + // Only error on the declarations that contributed to the intersecting spaces. + if (declarationSpaces & commonDeclarationSpacesForDefaultAndNonDefault) { + error(name, Diagnostics.Merged_declaration_0_cannot_include_a_default_export_declaration_Consider_adding_a_separate_export_default_0_declaration_instead, declarationNameToString(name)); + } + else if (declarationSpaces & commonDeclarationSpacesForExportsAndLocals) { + error(name, Diagnostics.Individual_declarations_in_merged_declaration_0_must_be_all_exported_or_all_local, declarationNameToString(name)); + } + } + } + + function getDeclarationSpaces(decl: Declaration): DeclarationSpaces { + let d = decl as Node; + switch (d.kind) { + case SyntaxKind.InterfaceDeclaration: + case SyntaxKind.TypeAliasDeclaration: + + // A jsdoc typedef and callback are, by definition, type aliases. + // falls through + case SyntaxKind.JSDocTypedefTag: + case SyntaxKind.JSDocCallbackTag: + case SyntaxKind.JSDocEnumTag: + return DeclarationSpaces.ExportType; + case SyntaxKind.ModuleDeclaration: + return isAmbientModule(d as ModuleDeclaration) || getModuleInstanceState(d as ModuleDeclaration) !== ModuleInstanceState.NonInstantiated + ? DeclarationSpaces.ExportNamespace | DeclarationSpaces.ExportValue + : DeclarationSpaces.ExportNamespace; + case SyntaxKind.ClassDeclaration: + case SyntaxKind.EnumDeclaration: + case SyntaxKind.EnumMember: + return DeclarationSpaces.ExportType | DeclarationSpaces.ExportValue; + case SyntaxKind.SourceFile: + return DeclarationSpaces.ExportType | DeclarationSpaces.ExportValue | DeclarationSpaces.ExportNamespace; + case SyntaxKind.ExportAssignment: + case SyntaxKind.BinaryExpression: + const node = d as ExportAssignment | BinaryExpression; + const expression = isExportAssignment(node) ? nod diff --git a/extensions/vscode-colorize-perf-tests/test/colorize-fixtures/test-treeView.ts b/extensions/vscode-colorize-perf-tests/test/colorize-fixtures/test-treeView.ts new file mode 100644 index 00000000000..08927639e76 --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/test/colorize-fixtures/test-treeView.ts @@ -0,0 +1,2067 @@ +/*--------------------------------------------------------------------------------------------- + * Copyright (c) Microsoft Corporation. All rights reserved. + * Licensed under the MIT License. See License.txt in the project root for license information. + *--------------------------------------------------------------------------------------------*/ + +import { DataTransfers, IDragAndDropData } from '../../../../base/browser/dnd.js'; +import * as DOM from '../../../../base/browser/dom.js'; +import * as cssJs from '../../../../base/browser/cssValue.js'; +import { renderMarkdownAsPlaintext } from '../../../../base/browser/markdownRenderer.js'; +import { ActionBar, IActionViewItemProvider } from '../../../../base/browser/ui/actionbar/actionbar.js'; +import { ActionViewItem } from '../../../../base/browser/ui/actionbar/actionViewItems.js'; +import { IHoverDelegate } from '../../../../base/browser/ui/hover/hoverDelegate.js'; +import { IIdentityProvider, IListVirtualDelegate } from '../../../../base/browser/ui/list/list.js'; +import { ElementsDragAndDropData, ListViewTargetSector } from '../../../../base/browser/ui/list/listView.js'; +import { IAsyncDataSource, ITreeContextMenuEvent, ITreeDragAndDrop, ITreeDragOverReaction, ITreeNode, ITreeRenderer, TreeDragOverBubble } from '../../../../base/browser/ui/tree/tree.js'; +import { CollapseAllAction } from '../../../../base/browser/ui/tree/treeDefaults.js'; +import { ActionRunner, IAction, Separator } from '../../../../base/common/actions.js'; +import { timeout } from '../../../../base/common/async.js'; +import { CancellationToken, CancellationTokenSource } from '../../../../base/common/cancellation.js'; +import { Codicon } from '../../../../base/common/codicons.js'; +import { isCancellationError } from '../../../../base/common/errors.js'; +import { Emitter, Event } from '../../../../base/common/event.js'; +import { createMatches, FuzzyScore } from '../../../../base/common/filters.js'; +import { IMarkdownString, isMarkdownString, MarkdownString } from '../../../../base/common/htmlContent.js'; +import { Disposable, DisposableStore, IDisposable, MutableDisposable, toDisposable } from '../../../../base/common/lifecycle.js'; +import { Mimes } from '../../../../base/common/mime.js'; +import { Schemas } from '../../../../base/common/network.js'; +import { basename, dirname } from '../../../../base/common/resources.js'; +import { isFalsyOrWhitespace } from '../../../../base/common/strings.js'; +import { isString } from '../../../../base/common/types.js'; +import { URI } from '../../../../base/common/uri.js'; +import { generateUuid } from '../../../../base/common/uuid.js'; +import './media/views.css'; +import { VSDataTransfer } from '../../../../base/common/dataTransfer.js'; +import { localize } from '../../../../nls.js'; +import { createActionViewItem, getContextMenuActions } from '../../../../platform/actions/browser/menuEntryActionViewItem.js'; +import { Action2, IMenuService, MenuId, MenuRegistry, registerAction2 } from '../../../../platform/actions/common/actions.js'; +import { CommandsRegistry, ICommandService } from '../../../../platform/commands/common/commands.js'; +import { IConfigurationService } from '../../../../platform/configuration/common/configuration.js'; +import { ContextKeyExpr, ContextKeyExpression, IContextKey, IContextKeyChangeEvent, IContextKeyService, RawContextKey } from '../../../../platform/contextkey/common/contextkey.js'; +import { IContextMenuService } from '../../../../platform/contextview/browser/contextView.js'; +import { FileKind } from '../../../../platform/files/common/files.js'; +import { IInstantiationService } from '../../../../platform/instantiation/common/instantiation.js'; +import { IKeybindingService } from '../../../../platform/keybinding/common/keybinding.js'; +import { ILabelService } from '../../../../platform/label/common/label.js'; +import { WorkbenchAsyncDataTree } from '../../../../platform/list/browser/listService.js'; +import { ILogService } from '../../../../platform/log/common/log.js'; +import { INotificationService } from '../../../../platform/notification/common/notification.js'; +import { IOpenerService } from '../../../../platform/opener/common/opener.js'; +import { IProgressService } from '../../../../platform/progress/common/progress.js'; +import { Registry } from '../../../../platform/registry/common/platform.js'; +import { ITelemetryService } from '../../../../platform/telemetry/common/telemetry.js'; +import { ColorScheme } from '../../../../platform/theme/common/theme.js'; +import { FileThemeIcon, FolderThemeIcon, IThemeService } from '../../../../platform/theme/common/themeService.js'; +import { ThemeIcon } from '../../../../base/common/themables.js'; +import { fillEditorsDragData } from '../../dnd.js'; +import { IResourceLabel, ResourceLabels } from '../../labels.js'; +import { API_OPEN_DIFF_EDITOR_COMMAND_ID, API_OPEN_EDITOR_COMMAND_ID } from '../editor/editorCommands.js'; +import { getLocationBasedViewColors, IViewPaneOptions, ViewPane } from './viewPane.js'; +import { IViewletViewOptions } from './viewsViewlet.js'; +import { Extensions, ITreeItem, ITreeItemLabel, ITreeView, ITreeViewDataProvider, ITreeViewDescriptor, ITreeViewDragAndDropController, IViewBadge, IViewDescriptorService, IViewsRegistry, ResolvableTreeItem, TreeCommand, TreeItemCollapsibleState, TreeViewItemHandleArg, TreeViewPaneHandleArg, ViewContainer, ViewContainerLocation } from '../../../common/views.js'; +import { IActivityService, NumberBadge } from '../../../services/activity/common/activity.js'; +import { IExtensionService } from '../../../services/extensions/common/extensions.js'; +import { IHoverService, WorkbenchHoverDelegate } from '../../../../platform/hover/browser/hover.js'; +import { CodeDataTransfers, LocalSelectionTransfer } from '../../../../platform/dnd/browser/dnd.js'; +import { toExternalVSDataTransfer } from '../../../../editor/browser/dnd.js'; +import { CheckboxStateHandler, TreeItemCheckbox } from './checkbox.js'; +import { setTimeout0 } from '../../../../base/common/platform.js'; +import { AriaRole } from '../../../../base/browser/ui/aria/aria.js'; +import { TelemetryTrustedValue } from '../../../../platform/telemetry/common/telemetryUtils.js'; +import { ITreeViewsDnDService } from '../../../../editor/common/services/treeViewsDndService.js'; +import { DraggedTreeItemsIdentifier } from '../../../../editor/common/services/treeViewsDnd.js'; +import { IMarkdownRenderResult, MarkdownRenderer } from '../../../../editor/browser/widget/markdownRenderer/browser/markdownRenderer.js'; +import type { IManagedHoverTooltipMarkdownString } from '../../../../base/browser/ui/hover/hover.js'; +import { parseLinkedText } from '../../../../base/common/linkedText.js'; +import { Button } from '../../../../base/browser/ui/button/button.js'; +import { defaultButtonStyles } from '../../../../platform/theme/browser/defaultStyles.js'; +import { IAccessibleViewInformationService } from '../../../services/accessibility/common/accessibleViewInformationService.js'; +import { Command } from '../../../../editor/common/languages.js'; + +export class TreeViewPane extends ViewPane { + + protected readonly treeView: ITreeView; + private _container: HTMLElement | undefined; + private _actionRunner: MultipleSelectionActionRunner; + + constructor( + options: IViewletViewOptions, + @IKeybindingService keybindingService: IKeybindingService, + @IContextMenuService contextMenuService: IContextMenuService, + @IConfigurationService configurationService: IConfigurationService, + @IContextKeyService contextKeyService: IContextKeyService, + @IViewDescriptorService viewDescriptorService: IViewDescriptorService, + @IInstantiationService instantiationService: IInstantiationService, + @IOpenerService openerService: IOpenerService, + @IThemeService themeService: IThemeService, + @ITelemetryService telemetryService: ITelemetryService, + @INotificationService notificationService: INotificationService, + @IHoverService hoverService: IHoverService, + @IAccessibleViewInformationService accessibleViewService: IAccessibleViewInformationService, + ) { + super({ ...(options as IViewPaneOptions), titleMenuId: MenuId.ViewTitle, donotForwardArgs: false }, keybindingService, contextMenuService, configurationService, contextKeyService, viewDescriptorService, instantiationService, openerService, themeService, telemetryService, hoverService, accessibleViewService); + const { treeView } = (Registry.as(Extensions.ViewsRegistry).getView(options.id)); + this.treeView = treeView; + this._register(this.treeView.onDidChangeActions(() => this.updateActions(), this)); + this._register(this.treeView.onDidChangeTitle((newTitle) => this.updateTitle(newTitle))); + this._register(this.treeView.onDidChangeDescription((newDescription) => this.updateTitleDescription(newDescription))); + this._register(toDisposable(() => { + if (this._container && this.treeView.container && (this._container === this.treeView.container)) { + this.treeView.setVisibility(false); + } + })); + this._register(this.onDidChangeBodyVisibility(() => this.updateTreeVisibility())); + this._register(this.treeView.onDidChangeWelcomeState(() => this._onDidChangeViewWelcomeState.fire())); + if (options.title !== this.treeView.title) { + this.updateTitle(this.treeView.title); + } + if (options.titleDescription !== this.treeView.description) { + this.updateTitleDescription(this.treeView.description); + } + this._actionRunner = new MultipleSelectionActionRunner(notificationService, () => this.treeView.getSelection()); + + this.updateTreeVisibility(); + } + + override focus(): void { + super.focus(); + this.treeView.focus(); + } + + protected override renderBody(container: HTMLElement): void { + this._container = container; + super.renderBody(container); + this.renderTreeView(container); + } + + override shouldShowWelcome(): boolean { + return ((this.treeView.dataProvider === undefined) || !!this.treeView.dataProvider.isTreeEmpty) && ((this.treeView.message === undefined) || (this.treeView.message === '')); + } + + protected override layoutBody(height: number, width: number): void { + super.layoutBody(height, width); + this.layoutTreeView(height, width); + } + + override getOptimalWidth(): number { + return this.treeView.getOptimalWidth(); + } + + protected renderTreeView(container: HTMLElement): void { + this.treeView.show(container); + } + + protected layoutTreeView(height: number, width: number): void { + this.treeView.layout(height, width); + } + + private updateTreeVisibility(): void { + this.treeView.setVisibility(this.isBodyVisible()); + } + + override getActionRunner() { + return this._actionRunner; + } + + override getActionsContext(): TreeViewPaneHandleArg { + return { $treeViewId: this.id, $focusedTreeItem: true, $selectedTreeItems: true }; + } + +} + +class Root implements ITreeItem { + label = { label: 'root' }; + handle = '0'; + parentHandle: string | undefined = undefined; + collapsibleState = TreeItemCollapsibleState.Expanded; + children: ITreeItem[] | undefined = undefined; +} + +function commandPreconditions(commandId: string): ContextKeyExpression | undefined { + const command = CommandsRegistry.getCommand(commandId); + if (command) { + const commandAction = MenuRegistry.getCommand(command.id); + return commandAction && commandAction.precondition; + } + return undefined; +} + +function isTreeCommandEnabled(treeCommand: TreeCommand | Command, contextKeyService: IContextKeyService): boolean { + const commandId: string = (treeCommand as TreeCommand).originalId ? (treeCommand as TreeCommand).originalId! : treeCommand.id; + const precondition = commandPreconditions(commandId); + if (precondition) { + return contextKeyService.contextMatchesRules(precondition); + } + + return true; +} + +interface RenderedMessage { element: HTMLElement; disposables: DisposableStore } + +function isRenderedMessageValue(messageValue: string | RenderedMessage | undefined): messageValue is RenderedMessage { + return !!messageValue && typeof messageValue !== 'string' && 'element' in messageValue && 'disposables' in messageValue; +} + +const noDataProviderMessage = localize('no-dataprovider', "There is no data provider registered that can provide view data."); + +export const RawCustomTreeViewContextKey = new RawContextKey('customTreeView', false); + +class Tree extends WorkbenchAsyncDataTree { } + +abstract class AbstractTreeView extends Disposable implements ITreeView { + + private isVisible: boolean = false; + private _hasIconForParentNode = false; + private _hasIconForLeafNode = false; + + private collapseAllContextKey: RawContextKey | undefined; + private collapseAllContext: IContextKey | undefined; + private collapseAllToggleContextKey: RawContextKey | undefined; + private collapseAllToggleContext: IContextKey | undefined; + private refreshContextKey: RawContextKey | undefined; + private refreshContext: IContextKey | undefined; + + private focused: boolean = false; + private domNode!: HTMLElement; + private treeContainer: HTMLElement | undefined; + private _messageValue: string | { element: HTMLElement; disposables: DisposableStore } | undefined; + private _canSelectMany: boolean = false; + private _manuallyManageCheckboxes: boolean = false; + private messageElement: HTMLElement | undefined; + private tree: Tree | undefined; + private treeLabels: ResourceLabels | undefined; + private treeViewDnd: CustomTreeViewDragAndDrop | undefined; + private _container: HTMLElement | undefined; + + private root: ITreeItem; + private markdownRenderer: MarkdownRenderer | undefined; + private elementsToRefresh: ITreeItem[] = []; + private lastSelection: readonly ITreeItem[] = []; + private lastActive: ITreeItem; + + private readonly _onDidExpandItem: Emitter = this._register(new Emitter()); + readonly onDidExpandItem: Event = this._onDidExpandItem.event; + + private readonly _onDidCollapseItem: Emitter = this._register(new Emitter()); + readonly onDidCollapseItem: Event = this._onDidCollapseItem.event; + + private _onDidChangeSelectionAndFocus: Emitter<{ selection: readonly ITreeItem[]; focus: ITreeItem }> = this._register(new Emitter<{ selection: readonly ITreeItem[]; focus: ITreeItem }>()); + readonly onDidChangeSelectionAndFocus: Event<{ selection: readonly ITreeItem[]; focus: ITreeItem }> = this._onDidChangeSelectionAndFocus.event; + + private readonly _onDidChangeVisibility: Emitter = this._register(new Emitter()); + readonly onDidChangeVisibility: Event = this._onDidChangeVisibility.event; + + private readonly _onDidChangeActions: Emitter = this._register(new Emitter()); + readonly onDidChangeActions: Event = this._onDidChangeActions.event; + + private readonly _onDidChangeWelcomeState: Emitter = this._register(new Emitter()); + readonly onDidChangeWelcomeState: Event = this._onDidChangeWelcomeState.event; + + private readonly _onDidChangeTitle: Emitter = this._register(new Emitter()); + readonly onDidChangeTitle: Event = this._onDidChangeTitle.event; + + private readonly _onDidChangeDescription: Emitter = this._register(new Emitter()); + readonly onDidChangeDescription: Event = this._onDidChangeDescription.event; + + private readonly _onDidChangeCheckboxState: Emitter = this._register(new Emitter()); + readonly onDidChangeCheckboxState: Event = this._onDidChangeCheckboxState.event; + + private readonly _onDidCompleteRefresh: Emitter = this._register(new Emitter()); + + constructor( + readonly id: string, + private _title: string, + @IThemeService private readonly themeService: IThemeService, + @IInstantiationService private readonly instantiationService: IInstantiationService, + @ICommandService private readonly commandService: ICommandService, + @IConfigurationService private readonly configurationService: IConfigurationService, + @IProgressService protected readonly progressService: IProgressService, + @IContextMenuService private readonly contextMenuService: IContextMenuService, + @IKeybindingService private readonly keybindingService: IKeybindingService, + @INotificationService private readonly notificationService: INotificationService, + @IViewDescriptorService private readonly viewDescriptorService: IViewDescriptorService, + @IHoverService private readonly hoverService: IHoverService, + @IContextKeyService private readonly contextKeyService: IContextKeyService, + @IActivityService private readonly activityService: IActivityService, + @ILogService private readonly logService: ILogService, + @IOpenerService private readonly openerService: IOpenerService + ) { + super(); + this.root = new Root(); + this.lastActive = this.root; + // Try not to add anything that could be costly to this constructor. It gets called once per tree view + // during startup, and anything added here can affect performance. + } + + private _isInitialized: boolean = false; + private initialize() { + if (this._isInitialized) { + return; + } + this._isInitialized = true; + + // Remember when adding to this method that it isn't called until the the view is visible, meaning that + // properties could be set and events could be fired before we're initialized and that this needs to be handled. + + this.contextKeyService.bufferChangeEvents(() => { + this.initializeShowCollapseAllAction(); + this.initializeCollapseAllToggle(); + this.initializeShowRefreshAction(); + }); + + this.treeViewDnd = this.instantiationService.createInstance(CustomTreeViewDragAndDrop, this.id); + if (this._dragAndDropController) { + this.treeViewDnd.controller = this._dragAndDropController; + } + + this._register(this.configurationService.onDidChangeConfiguration(e => { + if (e.affectsConfiguration('explorer.decorations')) { + this.doRefresh([this.root]); /** soft refresh **/ + } + })); + this._register(this.viewDescriptorService.onDidChangeLocation(({ views, from, to }) => { + if (views.some(v => v.id === this.id)) { + this.tree?.updateOptions({ overrideStyles: getLocationBasedViewColors(this.viewLocation).listOverrideStyles }); + } + })); + this.registerActions(); + + this.create(); + } + + get viewContainer(): ViewContainer { + return this.viewDescriptorService.getViewContainerByViewId(this.id)!; + } + + get viewLocation(): ViewContainerLocation { + return this.viewDescriptorService.getViewLocationById(this.id)!; + } + private _dragAndDropController: ITreeViewDragAndDropController | undefined; + get dragAndDropController(): ITreeViewDragAndDropController | undefined { + return this._dragAndDropController; + } + set dragAndDropController(dnd: ITreeViewDragAndDropController | undefined) { + this._dragAndDropController = dnd; + if (this.treeViewDnd) { + this.treeViewDnd.controller = dnd; + } + } + + private _dataProvider: ITreeViewDataProvider | undefined; + get dataProvider(): ITreeViewDataProvider | undefined { + return this._dataProvider; + } + + set dataProvider(dataProvider: ITreeViewDataProvider | undefined) { + if (dataProvider) { + if (this.visible) { + this.activate(); + } + const self = this; + this._dataProvider = new class implements ITreeViewDataProvider { + private _isEmpty: boolean = true; + private _onDidChangeEmpty: Emitter = new Emitter(); + public onDidChangeEmpty: Event = this._onDidChangeEmpty.event; + + get isTreeEmpty(): boolean { + return this._isEmpty; + } + + async getChildren(element?: ITreeItem): Promise { + const batches = await this.getChildrenBatch(element ? [element] : undefined); + return batches?.[0]; + } + + private updateEmptyState(nodes: ITreeItem[], childrenGroups: ITreeItem[][]): void { + if ((nodes.length === 1) && (nodes[0] instanceof Root)) { + const oldEmpty = this._isEmpty; + this._isEmpty = (childrenGroups.length === 0) || (childrenGroups[0].length === 0); + if (oldEmpty !== this._isEmpty) { + this._onDidChangeEmpty.fire(); + } + } + } + + private findCheckboxesUpdated(nodes: ITreeItem[], childrenGroups: ITreeItem[][]): ITreeItem[] { + if (childrenGroups.length === 0) { + return []; + } + const checkboxesUpdated: ITreeItem[] = []; + + for (let i = 0; i < nodes.length; i++) { + const node = nodes[i]; + const children = childrenGroups[i]; + for (const child of children) { + child.parent = node; + if (!self.manuallyManageCheckboxes && (node?.checkbox?.isChecked === true) && (child.checkbox?.isChecked === false)) { + child.checkbox.isChecked = true; + checkboxesUpdated.push(child); + } + } + } + return checkboxesUpdated; + } + + async getChildrenBatch(nodes?: ITreeItem[]): Promise { + let childrenGroups: ITreeItem[][]; + let checkboxesUpdated: ITreeItem[] = []; + if (nodes && nodes.every((node): node is Required => !!node.children)) { + childrenGroups = nodes.map(node => node.children); + } else { + nodes = nodes ?? [self.root]; + const batchedChildren = await (nodes.length === 1 && nodes[0] instanceof Root ? doGetChildrenOrBatch(dataProvider, undefined) : doGetChildrenOrBatch(dataProvider, nodes)); + for (let i = 0; i < nodes.length; i++) { + const node = nodes[i]; + node.children = batchedChildren ? batchedChildren[i] : undefined; + } + childrenGroups = batchedChildren ?? []; + checkboxesUpdated = this.findCheckboxesUpdated(nodes, childrenGroups); + } + + this.updateEmptyState(nodes, childrenGroups); + + if (checkboxesUpdated.length > 0) { + self._onDidChangeCheckboxState.fire(checkboxesUpdated); + } + return childrenGroups; + } + }; + if (this._dataProvider.onDidChangeEmpty) { + this._register(this._dataProvider.onDidChangeEmpty(() => { + this.updateCollapseAllToggle(); + this._onDidChangeWelcomeState.fire(); + })); + } + this.updateMessage(); + this.refresh(); + } else { + this._dataProvider = undefined; + this.treeDisposables.clear(); + this.activated = false; + this.updateMessage(); + } + + this._onDidChangeWelcomeState.fire(); + } + + private _message: string | IMarkdownString | undefined; + get message(): string | IMarkdownString | undefined { + return this._message; + } + + set message(message: string | IMarkdownString | undefined) { + this._message = message; + this.updateMessage(); + this._onDidChangeWelcomeState.fire(); + } + + get title(): string { + return this._title; + } + + set title(name: string) { + this._title = name; + this._onDidChangeTitle.fire(this._title); + } + + private _description: string | undefined; + get description(): string | undefined { + return this._description; + } + + set description(description: string | undefined) { + this._description = description; + this._onDidChangeDescription.fire(this._description); + } + + private _badge: IViewBadge | undefined; + private readonly _activity = this._register(new MutableDisposable()); + + get badge(): IViewBadge | undefined { + return this._badge; + } + + set badge(badge: IViewBadge | undefined) { + + if (this._badge?.value === badge?.value && + this._badge?.tooltip === badge?.tooltip) { + return; + } + + this._badge = badge; + if (badge) { + const activity = { + badge: new NumberBadge(badge.value, () => badge.tooltip), + priority: 50 + }; + this._activity.value = this.activityService.showViewActivity(this.id, activity); + } else { + this._activity.clear(); + } + } + + get canSelectMany(): boolean { + return this._canSelectMany; + } + + set canSelectMany(canSelectMany: boolean) { + const oldCanSelectMany = this._canSelectMany; + this._canSelectMany = canSelectMany; + if (this._canSelectMany !== oldCanSelectMany) { + this.tree?.updateOptions({ multipleSelectionSupport: this.canSelectMany }); + } + } + + get manuallyManageCheckboxes(): boolean { + return this._manuallyManageCheckboxes; + } + + set manuallyManageCheckboxes(manuallyManageCheckboxes: boolean) { + this._manuallyManageCheckboxes = manuallyManageCheckboxes; + } + + get hasIconForParentNode(): boolean { + return this._hasIconForParentNode; + } + + get hasIconForLeafNode(): boolean { + return this._hasIconForLeafNode; + } + + get visible(): boolean { + return this.isVisible; + } + + private initializeShowCollapseAllAction(startingValue: boolean = false) { + if (!this.collapseAllContext) { + this.collapseAllContextKey = new RawContextKey(`treeView.${this.id}.enableCollapseAll`, startingValue, localize('treeView.enableCollapseAll', "Whether the the tree view with id {0} enables collapse all.", this.id)); + this.collapseAllContext = this.collapseAllContextKey.bindTo(this.contextKeyService); + } + return true; + } + + get showCollapseAllAction(): boolean { + this.initializeShowCollapseAllAction(); + return !!this.collapseAllContext?.get(); + } + + set showCollapseAllAction(showCollapseAllAction: boolean) { + this.initializeShowCollapseAllAction(showCollapseAllAction); + this.collapseAllContext?.set(showCollapseAllAction); + } + + + private initializeShowRefreshAction(startingValue: boolean = false) { + if (!this.refreshContext) { + this.refreshContextKey = new RawContextKey(`treeView.${this.id}.enableRefresh`, startingValue, localize('treeView.enableRefresh', "Whether the tree view with id {0} enables refresh.", this.id)); + this.refreshContext = this.refreshContextKey.bindTo(this.contextKeyService); + } + } + + get showRefreshAction(): boolean { + this.initializeShowRefreshAction(); + return !!this.refreshContext?.get(); + } + + set showRefreshAction(showRefreshAction: boolean) { + this.initializeShowRefreshAction(showRefreshAction); + this.refreshContext?.set(showRefreshAction); + } + + private registerActions() { + const that = this; + this._register(registerAction2(class extends Action2 { + constructor() { + super({ + id: `workbench.actions.treeView.${that.id}.refresh`, + title: localize('refresh', "Refresh"), + menu: { + id: MenuId.ViewTitle, + when: ContextKeyExpr.and(ContextKeyExpr.equals('view', that.id), that.refreshContextKey), + group: 'navigation', + order: Number.MAX_SAFE_INTEGER - 1, + }, + icon: Codicon.refresh + }); + } + async run(): Promise { + return that.refresh(); + } + })); + this._register(registerAction2(class extends Action2 { + constructor() { + super({ + id: `workbench.actions.treeView.${that.id}.collapseAll`, + title: localize('collapseAll', "Collapse All"), + menu: { + id: MenuId.ViewTitle, + when: ContextKeyExpr.and(ContextKeyExpr.equals('view', that.id), that.collapseAllContextKey), + group: 'navigation', + order: Number.MAX_SAFE_INTEGER, + }, + precondition: that.collapseAllToggleContextKey, + icon: Codicon.collapseAll + }); + } + async run(): Promise { + if (that.tree) { + return new CollapseAllAction(that.tree, true).run(); + } + } + })); + } + + setVisibility(isVisible: boolean): void { + // Throughout setVisibility we need to check if the tree view's data provider still exists. + // This can happen because the `getChildren` call to the extension can return + // after the tree has been disposed. + + this.initialize(); + isVisible = !!isVisible; + if (this.isVisible === isVisible) { + return; + } + + this.isVisible = isVisible; + + if (this.tree) { + if (this.isVisible) { + DOM.show(this.tree.getHTMLElement()); + } else { + DOM.hide(this.tree.getHTMLElement()); // make sure the tree goes out of the tabindex world by hiding it + } + + if (this.isVisible && this.elementsToRefresh.length && this.dataProvider) { + this.doRefresh(this.elementsToRefresh); + this.elementsToRefresh = []; + } + } + + setTimeout0(() => { + if (this.dataProvider) { + this._onDidChangeVisibility.fire(this.isVisible); + } + }); + + if (this.visible) { + this.activate(); + } + } + + protected activated: boolean = false; + protected abstract activate(): void; + + focus(reveal: boolean = true, revealItem?: ITreeItem): void { + if (this.tree && this.root.children && this.root.children.length > 0) { + // Make sure the current selected element is revealed + const element = revealItem ?? this.tree.getSelection()[0]; + if (element && reveal) { + this.tree.reveal(element, 0.5); + } + + // Pass Focus to Viewer + this.tree.domFocus(); + } else if (this.tree && this.treeContainer && !this.treeContainer.classList.contains('hide')) { + this.tree.domFocus(); + } else { + this.domNode.focus(); + } + } + + show(container: HTMLElement): void { + this._container = container; + DOM.append(container, this.domNode); + } + + private create() { + this.domNode = DOM.$('.tree-explorer-viewlet-tree-view'); + this.messageElement = DOM.append(this.domNode, DOM.$('.message')); + this.updateMessage(); + this.treeContainer = DOM.append(this.domNode, DOM.$('.customview-tree')); + this.treeContainer.classList.add('file-icon-themable-tree', 'show-file-icons'); + const focusTracker = this._register(DOM.trackFocus(this.domNode)); + this._register(focusTracker.onDidFocus(() => this.focused = true)); + this._register(focusTracker.onDidBlur(() => this.focused = false)); + } + + private readonly treeDisposables: DisposableStore = this._register(new DisposableStore()); + protected createTree() { + this.treeDisposables.clear(); + const actionViewItemProvider = createActionViewItem.bind(undefined, this.instantiationService); + const treeMenus = this.treeDisposables.add(this.instantiationService.createInstance(TreeMenus, this.id)); + this.treeLabels = this.treeDisposables.add(this.instantiationService.createInstance(ResourceLabels, this)); + const dataSource = this.instantiationService.createInstance(TreeDataSource, this, (task: Promise) => this.progressService.withProgress({ location: this.id }, () => task)); + const aligner = this.treeDisposables.add(new Aligner(this.themeService)); + const checkboxStateHandler = this.treeDisposables.add(new CheckboxStateHandler()); + const renderer = this.treeDisposables.add(this.instantiationService.createInstance(TreeRenderer, this.id, treeMenus, this.treeLabels, actionViewItemProvider, aligner, checkboxStateHandler, () => this.manuallyManageCheckboxes)); + this.treeDisposables.add(renderer.onDidChangeCheckboxState(e => this._onDidChangeCheckboxState.fire(e))); + + const widgetAriaLabel = this._title; + + this.tree = this.treeDisposables.add(this.instantiationService.createInstance(Tree, this.id, this.treeContainer!, new TreeViewDelegate(), [renderer], + dataSource, { + identityProvider: new TreeViewIdentityProvider(), + accessibilityProvider: { + getAriaLabel(element: ITreeItem): string | null { + if (element.accessibilityInformation) { + return element.accessibilityInformation.label; + } + + if (isString(element.tooltip)) { + return element.tooltip; + } else { + if (element.resourceUri && !element.label) { + // The custom tree has no good information on what should be used for the aria label. + // Allow the tree widget's default aria label to be used. + return null; + } + let buildAriaLabel: string = ''; + if (element.label) { + buildAriaLabel += element.label.label + ' '; + } + if (element.description) { + buildAriaLabel += element.description; + } + return buildAriaLabel; + } + }, + getRole(element: ITreeItem): AriaRole | undefined { + return element.accessibilityInformation?.role ?? 'treeitem'; + }, + getWidgetAriaLabel(): string { + return widgetAriaLabel; + } + }, + keyboardNavigationLabelProvider: { + getKeyboardNavigationLabel: (item: ITreeItem) => { + return item.label ? item.label.label : (item.resourceUri ? basename(URI.revive(item.resourceUri)) : undefined); + } + }, + expandOnlyOnTwistieClick: (e: ITreeItem) => { + return !!e.command || !!e.checkbox || this.configurationService.getValue<'singleClick' | 'doubleClick'>('workbench.tree.expandMode') === 'doubleClick'; + }, + collapseByDefault: (e: ITreeItem): boolean => { + return e.collapsibleState !== TreeItemCollapsibleState.Expanded; + }, + multipleSelectionSupport: this.canSelectMany, + dnd: this.treeViewDnd, + overrideStyles: getLocationBasedViewColors(this.viewLocation).listOverrideStyles + }) as WorkbenchAsyncDataTree); + + this.treeDisposables.add(renderer.onDidChangeMenuContext(e => e.forEach(e => this.tree?.rerender(e)))); + + this.treeDisposables.add(this.tree); + treeMenus.setContextKeyService(this.tree.contextKeyService); + aligner.tree = this.tree; + const actionRunner = this.treeDisposables.add(new MultipleSelectionActionRunner(this.notificationService, () => this.tree!.getSelection())); + renderer.actionRunner = actionRunner; + + this.tree.contextKeyService.createKey(this.id, true); + const customTreeKey = RawCustomTreeViewContextKey.bindTo(this.tree.contextKeyService); + customTreeKey.set(true); + this.treeDisposables.add(this.tree.onContextMenu(e => this.onContextMenu(treeMenus, e, actionRunner))); + + this.treeDisposables.add(this.tree.onDidChangeSelection(e => { + this.lastSelection = e.elements; + this.lastActive = this.tree?.getFocus()[0] ?? this.lastActive; + this._onDidChangeSelectionAndFocus.fire({ selection: this.lastSelection, focus: this.lastActive }); + })); + this.treeDisposables.add(this.tree.onDidChangeFocus(e => { + if (e.elements.length && (e.elements[0] !== this.lastActive)) { + this.lastActive = e.elements[0]; + this.lastSelection = this.tree?.getSelection() ?? this.lastSelection; + this._onDidChangeSelectionAndFocus.fire({ selection: this.lastSelection, focus: this.lastActive }); + } + })); + this.treeDisposables.add(this.tree.onDidChangeCollapseState(e => { + if (!e.node.element) { + return; + } + + const element: ITreeItem = Array.isArray(e.node.element.element) ? e.node.element.element[0] : e.node.element.element; + if (e.node.collapsed) { + this._onDidCollapseItem.fire(element); + } else { + this._onDidExpandItem.fire(element); + } + })); + this.tree.setInput(this.root).then(() => this.updateContentAreas()); + + this.treeDisposables.add(this.tree.onDidOpen(async (e) => { + if (!e.browserEvent) { + return; + } + if (e.browserEvent.target && (e.browserEvent.target as HTMLElement).classList.contains(TreeItemCheckbox.checkboxClass)) { + return; + } + const selection = this.tree!.getSelection(); + const command = await this.resolveCommand(selection.length === 1 ? selection[0] : undefined); + + if (command && isTreeCommandEnabled(command, this.contextKeyService)) { + let args = command.arguments || []; + if (command.id === API_OPEN_EDITOR_COMMAND_ID || command.id === API_OPEN_DIFF_EDITOR_COMMAND_ID) { + // Some commands owned by us should receive the + // `IOpenEvent` as context to open properly + args = [...args, e]; + } + + try { + await this.commandService.executeCommand(command.id, ...args); + } catch (err) { + this.notificationService.error(err); + } + } + })); + + this.treeDisposables.add(treeMenus.onDidChange((changed) => { + if (this.tree?.hasNode(changed)) { + this.tree?.rerender(changed); + } + })); + } + + private async resolveCommand(element: ITreeItem | undefined): Promise { + let command = element?.command; + if (element && !command) { + if ((element instanceof ResolvableTreeItem) && element.hasResolve) { + await element.resolve(CancellationToken.None); + command = element.command; + } + } + return command; + } + + private onContextMenu(treeMenus: TreeMenus, treeEvent: ITreeContextMenuEvent, actionRunner: MultipleSelectionActionRunner): void { + this.hoverService.hideHover(); + const node: ITreeItem | null = treeEvent.element; + if (node === null) { + return; + } + const event: UIEvent = treeEvent.browserEvent; + + event.preventDefault(); + event.stopPropagation(); + + this.tree!.setFocus([node]); + let selected = this.canSelectMany ? this.getSelection() : []; + if (!selected.find(item => item.handle === node.handle)) { + selected = [node]; + } + + const actions = treeMenus.getResourceContextActions(selected); + if (!actions.length) { + return; + } + this.contextMenuService.showContextMenu({ + getAnchor: () => treeEvent.anchor, + + getActions: () => actions, + + getActionViewItem: (action) => { + const keybinding = this.keybindingService.lookupKeybinding(action.id); + if (keybinding) { + return new ActionViewItem(action, action, { label: true, keybinding: keybinding.getLabel() }); + } + return undefined; + }, + + onHide: (wasCancelled?: boolean) => { + if (wasCancelled) { + this.tree!.domFocus(); + } + }, + + getActionsContext: () => ({ $treeViewId: this.id, $treeItemHandle: node.handle } satisfies TreeViewItemHandleArg), + + actionRunner + }); + } + + protected updateMessage(): void { + if (this._message) { + this.showMessage(this._message); + } else if (!this.dataProvider) { + this.showMessage(noDataProviderMessage); + } else { + this.hideMessage(); + } + this.updateContentAreas(); + } + + private processMessage(message: IMarkdownString, disposables: DisposableStore): HTMLElement { + const lines = message.value.split('\n'); + const result: (IMarkdownRenderResult | HTMLElement)[] = []; + let hasFoundButton = false; + for (const line of lines) { + const linkedText = parseLinkedText(line); + + if (linkedText.nodes.length === 1 && typeof linkedText.nodes[0] !== 'string') { + const node = linkedText.nodes[0]; + const buttonContainer = document.createElement('div'); + buttonContainer.classList.add('button-container'); + const button = new Button(buttonContainer, { title: node.title, secondary: hasFoundButton, supportIcons: true, ...defaultButtonStyles }); + button.label = node.label; + button.onDidClick(_ => { + this.openerService.open(node.href, { allowCommands: true }); + }, null, disposables); + + const href = URI.parse(node.href); + if (href.scheme === Schemas.command) { + const preConditions = commandPreconditions(href.path); + if (preConditions) { + button.enabled = this.contextKeyService.contextMatchesRules(preConditions); + disposables.add(this.contextKeyService.onDidChangeContext(e => { + if (e.affectsSome(new Set(preConditions.keys()))) { + button.enabled = this.contextKeyService.contextMatchesRules(preConditions); + } + })); + } + } + + disposables.add(button); + hasFoundButton = true; + result.push(buttonContainer); + } else { + hasFoundButton = false; + const rendered = this.markdownRenderer!.render(new MarkdownString(line, { isTrusted: message.isTrusted, supportThemeIcons: message.supportThemeIcons, supportHtml: message.supportHtml })); + result.push(rendered.element); + disposables.add(rendered); + } + } + + const container = document.createElement('div'); + container.classList.add('rendered-message'); + for (const child of result) { + if (DOM.isHTMLElement(child)) { + container.appendChild(child); + } else { + container.appendChild(child.element); + } + } + return container; + } + + private showMessage(message: string | IMarkdownString): void { + if (isRenderedMessageValue(this._messageValue)) { + this._messageValue.disposables.dispose(); + } + if (isMarkdownString(message) && !this.markdownRenderer) { + this.markdownRenderer = this.instantiationService.createInstance(MarkdownRenderer, {}); + } + if (isMarkdownString(message)) { + const disposables = new DisposableStore(); + const renderedMessage = this.processMessage(message, disposables); + this._messageValue = { element: renderedMessage, disposables }; + } else { + this._messageValue = message; + } + if (!this.messageElement) { + return; + } + this.messageElement.classList.remove('hide'); + this.resetMessageElement(); + if (typeof this._messageValue === 'string' && !isFalsyOrWhitespace(this._messageValue)) { + this.messageElement.textContent = this._messageValue; + } else if (isRenderedMessageValue(this._messageValue)) { + this.messageElement.appendChild(this._messageValue.element); + } + this.layout(this._height, this._width); + } + + private hideMessage(): void { + this.resetMessageElement(); + this.messageElement?.classList.add('hide'); + this.layout(this._height, this._width); + } + + private resetMessageElement(): void { + if (this.messageElement) { + DOM.clearNode(this.messageElement); + } + } + + private _height: number = 0; + private _width: number = 0; + layout(height: number, width: number) { + if (height && width && this.messageElement && this.treeContainer) { + this._height = height; + this._width = width; + const treeHeight = height - DOM.getTotalHeight(this.messageElement); + this.treeContainer.style.height = treeHeight + 'px'; + this.tree?.layout(treeHeight, width); + } + } + + getOptimalWidth(): number { + if (this.tree) { + const parentNode = this.tree.getHTMLElement(); + const childNodes = ([] as HTMLElement[]).slice.call(parentNode.querySelectorAll('.outline-item-label > a')); + return DOM.getLargestChildWidth(parentNode, childNodes); + } + return 0; + } + + private updateCheckboxes(elements: readonly ITreeItem[]): ITreeItem[] { + return setCascadingCheckboxUpdates(elements); + } + + async refresh(elements?: readonly ITreeItem[], checkboxes?: readonly ITreeItem[]): Promise { + if (this.dataProvider && this.tree) { + if (this.refreshing) { + await Event.toPromise(this._onDidCompleteRefresh.event); + } + if (!elements) { + elements = [this.root]; + // remove all waiting elements to refresh if root is asked to refresh + this.elementsToRefresh = []; + } + for (const element of elements) { + element.children = undefined; // reset children + } + if (this.isVisible) { + const affectedElements = this.updateCheckboxes(checkboxes ?? []); + return this.doRefresh(elements.concat(affectedElements)); + } else { + if (this.elementsToRefresh.length) { + const seen: Set = new Set(); + this.elementsToRefresh.forEach(element => seen.add(element.handle)); + for (const element of elements) { + if (!seen.has(element.handle)) { + this.elementsToRefresh.push(element); + } + } + } else { + this.elementsToRefresh.push(...elements); + } + } + } + return undefined; + } + + async expand(itemOrItems: ITreeItem | ITreeItem[]): Promise { + const tree = this.tree; + if (!tree) { + return; + } + try { + itemOrItems = Array.isArray(itemOrItems) ? itemOrItems : [itemOrItems]; + for (const element of itemOrItems) { + await tree.expand(element, false); + } + } catch (e) { + // The extension could have changed the tree during the reveal. + // Because of that, we ignore errors. + } + } + + isCollapsed(item: ITreeItem): boolean { + return !!this.tree?.isCollapsed(item); + } + + setSelection(items: ITreeItem[]): void { + this.tree?.setSelection(items); + } + + getSelection(): ITreeItem[] { + return this.tree?.getSelection() ?? []; + } + + setFocus(item?: ITreeItem): void { + if (this.tree) { + if (item) { + this.focus(true, item); + this.tree.setFocus([item]); + } else if (this.tree.getFocus().length === 0) { + this.tree.setFocus([]); + } + } + } + + async reveal(item: ITreeItem): Promise { + if (this.tree) { + return this.tree.reveal(item); + } + } + + private refreshing: boolean = false; + private async doRefresh(elements: readonly ITreeItem[]): Promise { + const tree = this.tree; + if (tree && this.visible) { + this.refreshing = true; + const oldSelection = tree.getSelection(); + try { + await Promise.all(elements.map(element => tree.updateChildren(element, true, true))); + } catch (e) { + // When multiple calls are made to refresh the tree in quick succession, + // we can get a "Tree element not found" error. This is expected. + // Ideally this is fixable, so log instead of ignoring so the error is preserved. + this.logService.error(e); + } + const newSelection = tree.getSelection(); + if (oldSelection.length !== newSelection.length || oldSelection.some((value, index) => value.handle !== newSelection[index].handle)) { + this.lastSelection = newSelection; + this._onDidChangeSelectionAndFocus.fire({ selection: this.lastSelection, focus: this.lastActive }); + } + this.refreshing = false; + this._onDidCompleteRefresh.fire(); + this.updateContentAreas(); + if (this.focused) { + this.focus(false); + } + this.updateCollapseAllToggle(); + } + } + + private initializeCollapseAllToggle() { + if (!this.collapseAllToggleContext) { + this.collapseAllToggleContextKey = new RawContextKey(`treeView.${this.id}.toggleCollapseAll`, false, localize('treeView.toggleCollapseAll', "Whether collapse all is toggled for the tree view with id {0}.", this.id)); + this.collapseAllToggleContext = this.collapseAllToggleContextKey.bindTo(this.contextKeyService); + } + } + + private updateCollapseAllToggle() { + if (this.showCollapseAllAction) { + this.initializeCollapseAllToggle(); + this.collapseAllToggleContext?.set(!!this.root.children && (this.root.children.length > 0) && + this.root.children.some(value => value.collapsibleState !== TreeItemCollapsibleState.None)); + } + } + + private updateContentAreas(): void { + const isTreeEmpty = !this.root.children || this.root.children.length === 0; + // Hide tree container only when there is a message and tree is empty and not refreshing + if (this._messageValue && isTreeEmpty && !this.refreshing && this.treeContainer) { + // If there's a dnd controller then hiding the tree prevents it from being dragged into. + if (!this.dragAndDropController) { + this.treeContainer.classList.add('hide'); + } + this.domNode.setAttribute('tabindex', '0'); + } else if (this.treeContainer) { + this.treeContainer.classList.remove('hide'); + if (this.domNode === DOM.getActiveElement()) { + this.focus(); + } + this.domNode.removeAttribute('tabindex'); + } + } + + get container(): HTMLElement | undefined { + return this._container; + } +} + +class TreeViewIdentityProvider implements IIdentityProvider { + getId(element: ITreeItem): { toString(): string } { + return element.handle; + } +} + +class TreeViewDelegate implements IListVirtualDelegate { + + getHeight(element: ITreeItem): number { + return TreeRenderer.ITEM_HEIGHT; + } + + getTemplateId(element: ITreeItem): string { + return TreeRenderer.TREE_TEMPLATE_ID; + } +} + +async function doGetChildrenOrBatch(dataProvider: ITreeViewDataProvider, nodes: ITreeItem[] | undefined): Promise { + if (dataProvider.getChildrenBatch) { + return dataProvider.getChildrenBatch(nodes); + } else { + if (nodes) { + return Promise.all(nodes.map(node => dataProvider.getChildren(node).then(children => children ?? []))); + } else { + return [await dataProvider.getChildren()].filter(children => children !== undefined); + } + } +} + +class TreeDataSource implements IAsyncDataSource { + + constructor( + private treeView: ITreeView, + private withProgress: (task: Promise) => Promise + ) { + } + + hasChildren(element: ITreeItem): boolean { + return !!this.treeView.dataProvider && (element.collapsibleState !== TreeItemCollapsibleState.None); + } + + private batch: ITreeItem[] | undefined; + private batchPromise: Promise | undefined; + async getChildren(element: ITreeItem): Promise { + const dataProvider = this.treeView.dataProvider; + if (!dataProvider) { + return []; + } + if (this.batch === undefined) { + this.batch = [element]; + this.batchPromise = undefined; + } else { + this.batch.push(element); + } + const indexInBatch = this.batch.length - 1; + return new Promise((resolve, reject) => { + setTimeout(async () => { + const batch = this.batch; + this.batch = undefined; + if (!this.batchPromise) { + this.batchPromise = this.withProgress(doGetChildrenOrBatch(dataProvider, batch)); + } + try { + const result = await this.batchPromise; + resolve((result && (indexInBatch < result.length)) ? result[indexInBatch] : []); + } catch (e) { + if (!(e.message).startsWith('Bad progress location:')) { + reject(e); + } + } + }, 0); + }); + } +} + +interface ITreeExplorerTemplateData { + readonly container: HTMLElement; + readonly resourceLabel: IResourceLabel; + readonly icon: HTMLElement; + readonly checkboxContainer: HTMLElement; + checkbox?: TreeItemCheckbox; + readonly actionBar: ActionBar; +} + +class TreeRenderer extends Disposable implements ITreeRenderer { + static readonly ITEM_HEIGHT = 22; + static readonly TREE_TEMPLATE_ID = 'treeExplorer'; + + private readonly _onDidChangeCheckboxState: Emitter = this._register(new Emitter()); + readonly onDidChangeCheckboxState: Event = this._onDidChangeCheckboxState.event; + + private _onDidChangeMenuContext: Emitter = this._register(new Emitter()); + readonly onDidChangeMenuContext: Event = this._onDidChangeMenuContext.event; + + private _actionRunner: MultipleSelectionActionRunner | undefined; + private _hoverDelegate: IHoverDelegate; + private _hasCheckbox: boolean = false; + private _renderedElements = new Map; rendered: ITreeExplorerTemplateData }[]>(); // tree item handle to template data + + constructor( + private treeViewId: string, + private menus: TreeMenus, + private labels: ResourceLabels, + private actionViewItemProvider: IActionViewItemProvider, + private aligner: Aligner, + private checkboxStateHandler: CheckboxStateHandler, + private readonly manuallyManageCheckboxes: () => boolean, + @IThemeService private readonly themeService: IThemeService, + @IConfigurationService private readonly configurationService: IConfigurationService, + @ILabelService private readonly labelService: ILabelService, + @IContextKeyService private readonly contextKeyService: IContextKeyService, + @IHoverService private readonly hoverService: IHoverService, + @IInstantiationService instantiationService: IInstantiationService, + ) { + super(); + this._hoverDelegate = this._register(instantiationService.createInstance(WorkbenchHoverDelegate, 'mouse', false, {})); + this._register(this.themeService.onDidFileIconThemeChange(() => this.rerender())); + this._register(this.themeService.onDidColorThemeChange(() => this.rerender())); + this._register(checkboxStateHandler.onDidChangeCheckboxState(items => { + this.updateCheckboxes(items); + })); + this._register(this.contextKeyService.onDidChangeContext(e => this.onDidChangeContext(e))); + } + + get templateId(): string { + return TreeRenderer.TREE_TEMPLATE_ID; + } + + set actionRunner(actionRunner: MultipleSelectionActionRunner) { + this._actionRunner = actionRunner; + } + + renderTemplate(container: HTMLElement): ITreeExplorerTemplateData { + container.classList.add('custom-view-tree-node-item'); + + const checkboxContainer = DOM.append(container, DOM.$('')); + const resourceLabel = this.labels.create(container, { supportHighlights: true, hoverDelegate: this._hoverDelegate }); + const icon = DOM.prepend(resourceLabel.element, DOM.$('.custom-view-tree-node-item-icon')); + const actionsContainer = DOM.append(resourceLabel.element, DOM.$('.actions')); + const actionBar = new ActionBar(actionsContainer, { + actionViewItemProvider: this.actionViewItemProvider + }); + + return { resourceLabel, icon, checkboxContainer, actionBar, container }; + } + + private getHover(label: string | undefined, resource: URI | null, node: ITreeItem): string | IManagedHoverTooltipMarkdownString | undefined { + if (!(node instanceof ResolvableTreeItem) || !node.hasResolve) { + if (resource && !node.tooltip) { + return undefined; + } else if (node.tooltip === undefined) { + return label; + } else if (!isString(node.tooltip)) { + return { markdown: node.tooltip, markdownNotSupportedFallback: resource ? undefined : renderMarkdownAsPlaintext(node.tooltip) }; // Passing undefined as the fallback for a resource falls back to the old native hover + } else if (node.tooltip !== '') { + return node.tooltip; + } else { + return undefined; + } + } + + return { + markdown: typeof node.tooltip === 'string' ? node.tooltip : + (token: CancellationToken): Promise => { + return new Promise((resolve) => { + node.resolve(token).then(() => resolve(node.tooltip)); + }); + }, + markdownNotSupportedFallback: resource ? undefined : (label ?? '') // Passing undefined as the fallback for a resource falls back to the old native hover + }; + } + + renderElement(element: ITreeNode, index: number, templateData: ITreeExplorerTemplateData): void { + const node = element.element; + const resource = node.resourceUri ? URI.revive(node.resourceUri) : null; + const treeItemLabel: ITreeItemLabel | undefined = node.label ? node.label : (resource ? { label: basename(resource) } : undefined); + const description = isString(node.description) ? node.description : resource && node.description === true ? this.labelService.getUriLabel(dirname(resource), { relative: true }) : undefined; + const label = treeItemLabel ? treeItemLabel.label : undefined; + const matches = (treeItemLabel && treeItemLabel.highlights && label) ? treeItemLabel.highlights.map(([start, end]) => { + if (start < 0) { + start = label.length + start; + } + if (end < 0) { + end = label.length + end; + } + if ((start >= label.length) || (end > label.length)) { + return ({ start: 0, end: 0 }); + } + if (start > end) { + const swap = start; + start = end; + end = swap; + } + return ({ start, end }); + }) : undefined; + const icon = this.themeService.getColorTheme().type === ColorScheme.LIGHT ? node.icon : node.iconDark; + const iconUrl = icon ? URI.revive(icon) : undefined; + const title = this.getHover(label, resource, node); + + // reset + templateData.actionBar.clear(); + templateData.icon.style.color = ''; + + let commandEnabled = true; + if (node.command) { + commandEnabled = isTreeCommandEnabled(node.command, this.contextKeyService); + } + + this.renderCheckbox(node, templateData); + + if (resource) { + const fileDecorations = this.configurationService.getValue<{ colors: boolean; badges: boolean }>('explorer.decorations'); + const labelResource = resource ? resource : URI.parse('missing:_icon_resource'); + templateData.resourceLabel.setResource({ name: label, description, resource: labelResource }, { + fileKind: this.getFileKind(node), + title, + hideIcon: this.shouldHideResourceLabelIcon(iconUrl, node.themeIcon), + fileDecorations, + extraClasses: ['custom-view-tree-node-item-resourceLabel'], + matches: matches ? matches : createMatches(element.filterData), + strikethrough: treeItemLabel?.strikethrough, + disabledCommand: !commandEnabled, + labelEscapeNewLines: true, + forceLabel: !!node.label + }); + } else { + templateData.resourceLabel.setResource({ name: label, description }, { + title, + hideIcon: true, + extraClasses: ['custom-view-tree-node-item-resourceLabel'], + matches: matches ? matches : createMatches(element.filterData), + strikethrough: treeItemLabel?.strikethrough, + disabledCommand: !commandEnabled, + labelEscapeNewLines: true + }); + } + + if (iconUrl) { + templateData.icon.className = 'custom-view-tree-node-item-icon'; + templateData.icon.style.backgroundImage = cssJs.asCSSUrl(iconUrl); + } else { + let iconClass: string | undefined; + if (this.shouldShowThemeIcon(!!resource, node.themeIcon)) { + iconClass = ThemeIcon.asClassName(node.themeIcon); + if (node.themeIcon.color) { + templateData.icon.style.color = this.themeService.getColorTheme().getColor(node.themeIcon.color.id)?.toString() ?? ''; + } + } + templateData.icon.className = iconClass ? `custom-view-tree-node-item-icon ${iconClass}` : ''; + templateData.icon.style.backgroundImage = ''; + } + + if (!commandEnabled) { + templateData.icon.className = templateData.icon.className + ' disabled'; + if (templateData.container.parentElement) { + templateData.container.parentElement.className = templateData.container.parentElement.className + ' disabled'; + } + } + + templateData.actionBar.context = { $treeViewId: this.treeViewId, $treeItemHandle: node.handle } satisfies TreeViewItemHandleArg; + + const menuActions = this.menus.getResourceActions([node]); + templateData.actionBar.push(menuActions, { icon: true, label: false }); + + if (this._actionRunner) { + templateData.actionBar.actionRunner = this._actionRunner; + } + this.setAlignment(templateData.container, node); + + // remember rendered element, an element can be rendered multiple times + const renderedItems = this._renderedElements.get(element.element.handle) ?? []; + this._renderedElements.set(element.element.handle, [...renderedItems, { original: element, rendered: templateData }]); + } + + private rerender() { + // As we add items to the map during this call we can't directly use the map in the for loop + // but have to create a copy of the keys first + const keys = new Set(this._renderedElements.keys()); + for (const key of keys) { + const values = this._renderedElements.get(key) ?? []; + for (const value of values) { + this.disposeElement(value.original, 0, value.rendered); + this.renderElement(value.original, 0, value.rendered); + } + } + } + + private renderCheckbox(node: ITreeItem, templateData: ITreeExplorerTemplateData) { + if (node.checkbox) { + // The first time we find a checkbox we want to rerender the visible tree to adapt the alignment + if (!this._hasCheckbox) { + this._hasCheckbox = true; + this.rerender(); + } + if (!templateData.checkbox) { + const checkbox = new TreeItemCheckbox(templateData.checkboxContainer, this.checkboxStateHandler, this._hoverDelegate, this.hoverService); + templateData.checkbox = checkbox; + } + templateData.checkbox.render(node); + } else if (templateData.checkbox) { + templateData.checkbox.dispose(); + templateData.checkbox = undefined; + } + } + + private setAlignment(container: HTMLElement, treeItem: ITreeItem) { + container.parentElement!.classList.toggle('align-icon-with-twisty', !this._hasCheckbox && this.aligner.alignIconWithTwisty(treeItem)); + } + + private shouldHideResourceLabelIcon(iconUrl: URI | undefined, icon: ThemeIcon | undefined): boolean { + // We always hide the resource label in favor of the iconUrl when it's provided. + // When `ThemeIcon` is provided, we hide the resource label icon in favor of it only if it's a not a file icon. + return (!!iconUrl || (!!icon && !this.isFileKindThemeIcon(icon))); + } + + private shouldShowThemeIcon(hasResource: boolean, icon: ThemeIcon | undefined): icon is ThemeIcon { + if (!icon) { + return false; + } + + // If there's a resource and the icon is a file icon, then the icon (or lack thereof) will already be coming from the + // icon theme and should use whatever the icon theme has provided. + return !(hasResource && this.isFileKindThemeIcon(icon)); + } + + private isFolderThemeIcon(icon: ThemeIcon | undefined): boolean { + return icon?.id === FolderThemeIcon.id; + } + + private isFileKindThemeIcon(icon: ThemeIcon | undefined): boolean { + if (icon) { + return icon.id === FileThemeIcon.id || this.isFolderThemeIcon(icon); + } else { + return false; + } + } + + private getFileKind(node: ITreeItem): FileKind { + if (node.themeIcon) { + switch (node.themeIcon.id) { + case FileThemeIcon.id: + return FileKind.FILE; + case FolderThemeIcon.id: + return FileKind.FOLDER; + } + } + return node.collapsibleState === TreeItemCollapsibleState.Collapsed || node.collapsibleState === TreeItemCollapsibleState.Expanded ? FileKind.FOLDER : FileKind.FILE; + } + + private onDidChangeContext(e: IContextKeyChangeEvent) { + const items: ITreeItem[] = []; + for (const [_, elements] of this._renderedElements) { + for (const element of elements) { + if (e.affectsSome(this.menus.getElementOverlayContexts(element.original.element)) || e.affectsSome(this.menus.getEntireMenuContexts())) { + items.push(element.original.element); + } + } + } + if (items.length) { + this._onDidChangeMenuContext.fire(items); + } + } + + private updateCheckboxes(items: ITreeItem[]) { + let allItems: ITreeItem[] = []; + + if (!this.manuallyManageCheckboxes()) { + allItems = setCascadingCheckboxUpdates(items); + } + + allItems.forEach(item => { + const renderedItems = this._renderedElements.get(item.handle); + if (renderedItems) { + renderedItems.forEach(renderedItems => renderedItems.rendered.checkbox?.render(item)); + } + }); + this._onDidChangeCheckboxState.fire(allItems); + } + + disposeElement(resource: ITreeNode, index: number, templateData: ITreeExplorerTemplateData): void { + const itemRenders = this._renderedElements.get(resource.element.handle) ?? []; + const renderedIndex = itemRenders.findIndex(renderedItem => templateData === renderedItem.rendered); + + if (itemRenders.length === 1) { + this._renderedElements.delete(resource.element.handle); + } else if (itemRenders.length > 0) { + itemRenders.splice(renderedIndex, 1); + } + + templateData.checkbox?.dispose(); + templateData.checkbox = undefined; + } + + disposeTemplate(templateData: ITreeExplorerTemplateData): void { + templateData.resourceLabel.dispose(); + templateData.actionBar.dispose(); + } +} + +class Aligner extends Disposable { + private _tree: WorkbenchAsyncDataTree | undefined; + + constructor(private themeService: IThemeService) { + super(); + } + + set tree(tree: WorkbenchAsyncDataTree) { + this._tree = tree; + } + + public alignIconWithTwisty(treeItem: ITreeItem): boolean { + if (treeItem.collapsibleState !== TreeItemCollapsibleState.None) { + return false; + } + if (!this.hasIcon(treeItem)) { + return false; + } + + if (this._tree) { + const parent: ITreeItem = this._tree.getParentElement(treeItem) || this._tree.getInput(); + if (this.hasIcon(parent)) { + return !!parent.children && parent.children.some(c => c.collapsibleState !== TreeItemCollapsibleState.None && !this.hasIcon(c)); + } + return !!parent.children && parent.children.every(c => c.collapsibleState === TreeItemCollapsibleState.None || !this.hasIcon(c)); + } else { + return false; + } + } + + private hasIcon(node: ITreeItem): boolean { + const icon = this.themeService.getColorTheme().type === ColorScheme.LIGHT ? node.icon : node.iconDark; + if (icon) { + return true; + } + if (node.resourceUri || node.themeIcon) { + const fileIconTheme = this.themeService.getFileIconTheme(); + const isFolder = node.themeIcon ? node.themeIcon.id === FolderThemeIcon.id : node.collapsibleState !== TreeItemCollapsibleState.None; + if (isFolder) { + return fileIconTheme.hasFileIcons && fileIconTheme.hasFolderIcons; + } + return fileIconTheme.hasFileIcons; + } + return false; + } +} + +class MultipleSelectionActionRunner extends ActionRunner { + + constructor(notificationService: INotificationService, private getSelectedResources: (() => ITreeItem[])) { + super(); + this._register(this.onDidRun(e => { + if (e.error && !isCancellationError(e.error)) { + notificationService.error(localize('command-error', 'Error running command {1}: {0}. This is likely caused by the extension that contributes {1}.', e.error.message, e.action.id)); + } + })); + } + + protected override async runAction(action: IAction, context: TreeViewItemHandleArg | TreeViewPaneHandleArg): Promise { + const selection = this.getSelectedResources(); + let selectionHandleArgs: TreeViewItemHandleArg[] | undefined = undefined; + let actionInSelected: boolean = false; + if (selection.length > 1) { + selectionHandleArgs = selection.map(selected => { + if ((selected.handle === (context as TreeViewItemHandleArg).$treeItemHandle) || (context as TreeViewPaneHandleArg).$selectedTreeItems) { + actionInSelected = true; + } + return { $treeViewId: context.$treeViewId, $treeItemHandle: selected.handle }; + }); + } + + if (!actionInSelected && selectionHandleArgs) { + selectionHandleArgs = undefined; + } + + await action.run(context, selectionHandleArgs); + } +} + +class TreeMenus implements IDisposable { + private contextKeyService: IContextKeyService | undefined; + private _onDidChange = new Emitter(); + public readonly onDidChange = this._onDidChange.event; + + constructor( + private id: string, + @IMenuService private readonly menuService: IMenuService + ) { } + + /** + * Gets only the actions that apply to all of the given elements. + */ + getResourceActions(elements: ITreeItem[]): IAction[] { + const actions = this.getActions(this.getMenuId(), elements); + return actions.primary; + } + + /** + * Gets only the actions that apply to all of the given elements. + */ + getResourceContextActions(elements: ITreeItem[]): IAction[] { + return this.getActions(this.getMenuId(), elements).secondary; + } + + public setContextKeyService(service: IContextKeyService) { + this.contextKeyService = service; + } + + private filterNonUniversalActions(groups: Map[], newActions: IAction[]) { + const newActionsSet: Set = new Set(newActions.map(a => a.id)); + for (const group of groups) { + const actions = group.keys(); + for (const action of actions) { + if (!newActionsSet.has(action)) { + group.delete(action); + } + } + } + } + + private buildMenu(groups: Map[]): IAction[] { + const result: IAction[] = []; + for (const group of groups) { + if (group.size > 0) { + if (result.length) { + result.push(new Separator()); + } + result.push(...group.values()); + } + } + return result; + } + + private createGroups(actions: IAction[]): Map[] { + const groups: Map[] = []; + let group: Map = new Map(); + for (const action of actions) { + if (action instanceof Separator) { + groups.push(group); + group = new Map(); + } else { + group.set(action.id, action); + } + } + groups.push(group); + return groups; + } + + public getElementOverlayContexts(element: ITreeItem): Map { + return new Map([ + ['view', this.id], + ['viewItem', element.contextValue] + ]); + } + + public getEntireMenuContexts(): ReadonlySet { + return this.menuService.getMenuContexts(this.getMenuId()); + } + + public getMenuId(): MenuId { + return MenuId.ViewItemContext; + } + + private getActions(menuId: MenuId, elements: ITreeItem[]): { primary: IAction[]; secondary: IAction[] } { + if (!this.contextKeyService) { + return { primary: [], secondary: [] }; + } + + let primaryGroups: Map[] = []; + let secondaryGroups: Map[] = []; + for (let i = 0; i < elements.length; i++) { + const element = elements[i]; + const contextKeyService = this.contextKeyService.createOverlay(this.getElementOverlayContexts(element)); + + const menuData = this.menuService.getMenuActions(menuId, contextKeyService, { shouldForwardArgs: true }); + + const result = getContextMenuActions(menuData, 'inline'); + if (i === 0) { + primaryGroups = this.createGroups(result.primary); + secondaryGroups = this.createGroups(result.secondary); + } else { + this.filterNonUniversalActions(primaryGroups, result.primary); + this.filterNonUniversalActions(secondaryGroups, result.secondary); + } + } + + return { primary: this.buildMenu(primaryGroups), secondary: this.buildMenu(secondaryGroups) }; + } + + dispose() { + this.contextKeyService = undefined; + } +} + +export class CustomTreeView extends AbstractTreeView { + + constructor( + id: string, + title: string, + private readonly extensionId: string, + @IThemeService themeService: IThemeService, + @IInstantiationService instantiationService: IInstantiationService, + @ICommandService commandService: ICommandService, + @IConfigurationService configurationService: IConfigurationService, + @IProgressService progressService: IProgressService, + @IContextMenuService contextMenuService: IContextMenuService, + @IKeybindingService keybindingService: IKeybindingService, + @INotificationService notificationService: INotificationService, + @IViewDescriptorService viewDescriptorService: IViewDescriptorService, + @IContextKeyService contextKeyService: IContextKeyService, + @IHoverService hoverService: IHoverService, + @IExtensionService private readonly extensionService: IExtensionService, + @IActivityService activityService: IActivityService, + @ITelemetryService private readonly telemetryService: ITelemetryService, + @ILogService logService: ILogService, + @IOpenerService openerService: IOpenerService + ) { + super(id, title, themeService, instantiationService, commandService, configurationService, progressService, contextMenuService, keybindingService, notificationService, viewDescriptorService, hoverService, contextKeyService, activityService, logService, openerService); + } + + protected activate() { + if (!this.activated) { + type ExtensionViewTelemetry = { + extensionId: TelemetryTrustedValue; + id: string; + }; + type ExtensionViewTelemetryMeta = { + extensionId: { classification: 'SystemMetaData'; purpose: 'FeatureInsight'; comment: 'Id of the extension' }; + id: { classification: 'SystemMetaData'; purpose: 'FeatureInsight'; comment: 'Id of the view' }; + owner: 'digitarald'; + comment: 'Helps to gain insights on what extension contributed views are most popular'; + }; + this.telemetryService.publicLog2('Extension:ViewActivate', { + extensionId: new TelemetryTrustedValue(this.extensionId), + id: this.id, + }); + this.createTree(); + this.progressService.withProgress({ location: this.id }, () => this.extensionService.activateByEvent(`onView:${this.id}`)) + .then(() => timeout(2000)) + .then(() => { + this.updateMessage(); + }); + this.activated = true; + } + } +} + +export class TreeView extends AbstractTreeView { + + protected activate() { + if (!this.activated) { + this.createTree(); + this.activated = true; + } + } +} + +interface TreeDragSourceInfo { + id: string; + itemHandles: string[]; +} + +export class CustomTreeViewDragAndDrop implements ITreeDragAndDrop { + private readonly treeMimeType: string; + private readonly treeItemsTransfer = LocalSelectionTransfer.getInstance(); + private dragCancellationToken: CancellationTokenSource | undefined; + + constructor( + private readonly treeId: string, + @ILabelService private readonly labelService: ILabelService, + @IInstantiationService private readonly instantiationService: IInstantiationService, + @ITreeViewsDnDService private readonly treeViewsDragAndDropService: ITreeViewsDnDService, + @ILogService private readonly logService: ILogService) { + this.treeMimeType = `application/vnd.code.tree.${treeId.toLowerCase()}`; + } + + private dndController: ITreeViewDragAndDropController | undefined; + set controller(controller: ITreeViewDragAndDropController | undefined) { + this.dndController = controller; + } + + private handleDragAndLog(dndController: ITreeViewDragAndDropController, itemHandles: string[], uuid: string, dragCancellationToken: CancellationToken): Promise { + return dndController.handleDrag(itemHandles, uuid, dragCancellationToken).then(additionalDataTransfer => { + if (additionalDataTransfer) { + const unlistedTypes: string[] = []; + for (const item of additionalDataTransfer) { + if ((item[0] !== this.treeMimeType) && (dndController.dragMimeTypes.findIndex(value => value === item[0]) < 0)) { + unlistedTypes.push(item[0]); + } + } + if (unlistedTypes.length) { + this.logService.warn(`Drag and drop controller for tree ${this.treeId} adds the following data transfer types but does not declare them in dragMimeTypes: ${unlistedTypes.join(', ')}`); + } + } + return additionalDataTransfer; + }); + } + + private addExtensionProvidedTransferTypes(originalEvent: DragEvent, itemHandles: string[]) { + if (!originalEvent.dataTransfer || !this.dndController) { + return; + } + const uuid = generateUuid(); + + this.dragCancellationToken = new CancellationTokenSource(); + this.treeViewsDragAndDropService.addDragOperationTransfer(uuid, this.handleDragAndLog(this.dndController, itemHandles, uuid, this.dragCancellationToken.token)); + this.treeItemsTransfer.setData([new DraggedTreeItemsIdentifier(uuid)], DraggedTreeItemsIdentifier.prototype); + originalEvent.dataTransfer.clearData(Mimes.text); + if (this.dndController.dragMimeTypes.find((element) => element === Mimes.uriList)) { + // Add the type that the editor knows + originalEvent.dataTransfer?.setData(DataTransfers.RESOURCES, ''); + } + this.dndController.dragMimeTypes.forEach(supportedType => { + originalEvent.dataTransfer?.setData(supportedType, ''); + }); + } + + private addResourceInfoToTransfer(originalEvent: DragEvent, resources: URI[]) { + if (resources.length && originalEvent.dataTransfer) { + // Apply some datatransfer types to allow for dragging the element outside of the application + this.instantiationService.invokeFunction(accessor => fillEditorsDragData(accessor, resources, originalEvent)); + + // The only custom data transfer we set from the explorer is a file transfer + // to be able to DND between multiple code file explorers across windows + const fileResources = resources.filter(s => s.scheme === Schemas.file).map(r => r.fsPath); + if (fileResources.length) { + originalEvent.dataTransfer.setData(CodeDataTransfers.FILES, JSON.stringify(fileResources)); + } + } + } + + onDragStart(data: IDragAndDropData, originalEvent: DragEvent): void { + if (originalEvent.dataTransfer) { + const treeItemsData = (data as ElementsDragAndDropData).getData(); + const resources: URI[] = []; + const sourceInfo: TreeDragSourceInfo = { + id: this.treeId, + itemHandles: [] + }; + treeItemsData.forEach(item => { + sourceInfo.itemHandles.push(item.handle); + if (item.resourceUri) { + resources.push(URI.revive(item.resourceUri)); + } + }); + this.addResourceInfoToTransfer(originalEvent, resources); + this.addExtensionProvidedTransferTypes(originalEvent, sourceInfo.itemHandles); + originalEvent.dataTransfer.setData(this.treeMimeType, + JSON.stringify(sourceInfo)); + } + } + + private debugLog(types: Set) { + if (types.size) { + this.logService.debug(`TreeView dragged mime types: ${Array.from(types).join(', ')}`); + } else { + this.logService.debug(`TreeView dragged with no supported mime types.`); + } + } + + onDragOver(data: IDragAndDropData, targetElement: ITreeItem, targetIndex: number, targetSector: ListViewTargetSector | undefined, originalEvent: DragEvent): boolean | ITreeDragOverReaction { + const dataTransfer = toExternalVSDataTransfer(originalEvent.dataTransfer!); + + const types = new Set(Array.from(dataTransfer, x => x[0])); + + if (originalEvent.dataTransfer) { + // Also add uri-list if we have any files. At this stage we can't actually access the file itself though. + for (const item of originalEvent.dataTransfer.items) { + if (item.kind === 'file' || item.type === DataTransfers.RESOURCES.toLowerCase()) { + types.add(Mimes.uriList); + break; + } + } + } + + this.debugLog(types); + + const dndController = this.dndController; + if (!dndController || !originalEvent.dataTransfer || (dndController.dropMimeTypes.length === 0)) { + return false; + } + const dragContainersSupportedType = Array.from(types).some((value, index) => { + if (value === this.treeMimeType) { + return true; + } else { + return dndController.dropMimeTypes.indexOf(value) >= 0; + } + }); + if (dragContainersSupportedType) { + return { accept: true, bubble: TreeDragOverBubble.Down, autoExpand: true }; + } + return false; + } + + getDragURI(element: ITreeItem): string | null { + if (!this.dndController) { + return null; + } + return element.resourceUri ? URI.revive(element.resourceUri).toString() : element.handle; + } + + getDragLabel?(elements: ITreeItem[]): string | undefined { + if (!this.dndController) { + return undefined; + } + if (elements.length > 1) { + return String(elements.length); + } + const element = elements[0]; + return element.label ? element.label.label : (element.resourceUri ? this.labelService.getUriLabel(URI.revive(element.resourceUri)) : undefined); + } + + async drop(data: IDragAndDropData, targetNode: ITreeItem | undefined, targetIndex: number | undefined, targetSector: ListViewTargetSector | undefined, originalEvent: DragEvent): Promise { + const dndController = this.dndController; + if (!originalEvent.dataTransfer || !dndController) { + return; + } + + let treeSourceInfo: TreeDragSourceInfo | undefined; + let willDropUuid: string | undefined; + if (this.treeItemsTransfer.hasData(DraggedTreeItemsIdentifier.prototype)) { + willDropUuid = this.treeItemsTransfer.getData(DraggedTreeItemsIdentifier.prototype)![0].identifier; + } + + const originalDataTransfer = toExternalVSDataTransfer(originalEvent.dataTransfer, true); + + const outDataTransfer = new VSDataTransfer(); + for (const [type, item] of originalDataTransfer) { + if (type === this.treeMimeType || dndController.dropMimeTypes.includes(type) || (item.asFile() && dndController.dropMimeTypes.includes(DataTransfers.FILES.toLowerCase()))) { + outDataTransfer.append(type, item); + if (type === this.treeMimeType) { + try { + treeSourceInfo = JSON.parse(await item.asString()); + } catch { + // noop + } + } + } + } + + const additionalDataTransfer = await this.treeViewsDragAndDropService.removeDragOperationTransfer(willDropUuid); + if (additionalDataTransfer) { + for (const [type, item] of additionalDataTransfer) { + outDataTransfer.append(type, item); + } + } + return dndController.handleDrop(outDataTransfer, targetNode, CancellationToken.None, willDropUuid, treeSourceInfo?.id, treeSourceInfo?.itemHandles); + } + + onDragEnd(originalEvent: DragEvent): void { + // Check if the drag was cancelled. + if (originalEvent.dataTransfer?.dropEffect === 'none') { + this.dragCancellationToken?.cancel(); + } + } + + dispose(): void { } +} + +function setCascadingCheckboxUpdates(items: readonly ITreeItem[]) { + const additionalItems: ITreeItem[] = []; + + for (const item of items) { + if (item.checkbox !== undefined) { + + const checkChildren = (currentItem: ITreeItem) => { + for (const child of (currentItem.children ?? [])) { + if ((child.checkbox !== undefined) && (currentItem.checkbox !== undefined) && (child.checkbox.isChecked !== currentItem.checkbox.isChecked)) { + child.checkbox.isChecked = currentItem.checkbox.isChecked; + additionalItems.push(child); + checkChildren(child); + } + } + }; + checkChildren(item); + + const visitedParents: Set = new Set(); + const checkParents = (currentItem: ITreeItem) => { + if (currentItem.parent && (currentItem.parent.checkbox !== undefined) && currentItem.parent.children) { + if (visitedParents.has(currentItem.parent)) { + return; + } else { + visitedParents.add(currentItem.parent); + } + + let someUnchecked = false; + let someChecked = false; + for (const child of currentItem.parent.children) { + if (someUnchecked && someChecked) { + break; + } + if (child.checkbox !== undefined) { + if (child.checkbox.isChecked) { + someChecked = true; + } else { + someUnchecked = true; + } + } + } + if (someChecked && !someUnchecked && (currentItem.parent.checkbox.isChecked !== true)) { + currentItem.parent.checkbox.isChecked = true; + additionalItems.push(currentItem.parent); + checkParents(currentItem.parent); + } else if (someUnchecked && (currentItem.parent.checkbox.isChecked !== false)) { + currentItem.parent.checkbox.isChecked = false; + additionalItems.push(currentItem.parent); + checkParents(currentItem.parent); + } + } + }; + checkParents(item); + } + } + + return items.concat(additionalItems); +} diff --git a/extensions/vscode-colorize-perf-tests/test/colorize-fixtures/test.ts b/extensions/vscode-colorize-perf-tests/test/colorize-fixtures/test.ts new file mode 100644 index 00000000000..b9c80efd386 --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/test/colorize-fixtures/test.ts @@ -0,0 +1,111 @@ +/* Game of Life + * Implemented in TypeScript + * To learn more about TypeScript, please visit http://www.typescriptlang.org/ + */ + +module Conway { + + export class Cell { + public row: number; + public col: number; + public live: boolean; + + constructor(row: number, col: number, live: boolean) { + this.row = row; + this.col = col; + this.live = live + } + } + + export class GameOfLife { + private gridSize: number; + private canvasSize: number; + private lineColor: string; + private liveColor: string; + private deadColor: string; + private initialLifeProbability: number; + private animationRate: number; + private cellSize: number; + private world; + + + constructor() { + this.gridSize = 50; + this.canvasSize = 600; + this.lineColor = '#cdcdcd'; + this.liveColor = '#666'; + this.deadColor = '#eee'; + this.initialLifeProbability = 0.5; + this.animationRate = 60; + this.cellSize = 0; + this.world = this.createWorld(); + this.circleOfLife(); + } + + public createWorld() { + return this.travelWorld( (cell : Cell) => { + cell.live = Math.random() < this.initialLifeProbability; + return cell; + }); + } + + public circleOfLife() : void { + this.world = this.travelWorld( (cell: Cell) => { + cell = this.world[cell.row][cell.col]; + this.draw(cell); + return this.resolveNextGeneration(cell); + }); + setTimeout( () => {this.circleOfLife()}, this.animationRate); + } + + public resolveNextGeneration(cell : Cell) { + var count = this.countNeighbors(cell); + var newCell = new Cell(cell.row, cell.col, cell.live); + if(count < 2 || count > 3) newCell.live = false; + else if(count == 3) newCell.live = true; + return newCell; + } + + public countNeighbors(cell : Cell) { + var neighbors = 0; + for(var row = -1; row <=1; row++) { + for(var col = -1; col <= 1; col++) { + if(row == 0 && col == 0) continue; + if(this.isAlive(cell.row + row, cell.col + col)) { + neighbors++; + } + } + } + return neighbors; + } + + public isAlive(row : number, col : number) { + if(row < 0 || col < 0 || row >= this.gridSize || col >= this.gridSize) return false; + return this.world[row][col].live; + } + + public travelWorld(callback) { + var result = []; + for(var row = 0; row < this.gridSize; row++) { + var rowData = []; + for(var col = 0; col < this.gridSize; col++) { + rowData.push(callback(new Cell(row, col, false))); + } + result.push(rowData); + } + return result; + } + + public draw(cell : Cell) { + if(this.cellSize == 0) this.cellSize = this.canvasSize/this.gridSize; + + this.context.strokeStyle = this.lineColor; + this.context.strokeRect(cell.row * this.cellSize, cell.col*this.cellSize, this.cellSize, this.cellSize); + this.context.fillStyle = cell.live ? this.liveColor : this.deadColor; + this.context.fillRect(cell.row * this.cellSize, cell.col*this.cellSize, this.cellSize, this.cellSize); + } + + } +} + +var game = new Conway.GameOfLife(); diff --git a/extensions/vscode-colorize-perf-tests/tsconfig.json b/extensions/vscode-colorize-perf-tests/tsconfig.json new file mode 100644 index 00000000000..7234fdfeb97 --- /dev/null +++ b/extensions/vscode-colorize-perf-tests/tsconfig.json @@ -0,0 +1,13 @@ +{ + "extends": "../tsconfig.base.json", + "compilerOptions": { + "outDir": "./out", + "types": [ + "node" + ] + }, + "include": [ + "src/**/*", + "../../src/vscode-dts/vscode.d.ts" + ] +} diff --git a/src/vs/editor/browser/services/treeSitter/treeSitterParserService.ts b/src/vs/editor/browser/services/treeSitter/treeSitterParserService.ts index c865456f6a2..81d1736d775 100644 --- a/src/vs/editor/browser/services/treeSitter/treeSitterParserService.ts +++ b/src/vs/editor/browser/services/treeSitter/treeSitterParserService.ts @@ -5,7 +5,7 @@ import type { Parser } from '@vscode/tree-sitter-wasm'; import { AppResourcePath, FileAccess, nodeModulesAsarUnpackedPath, nodeModulesPath } from '../../../../base/common/network.js'; -import { EDITOR_EXPERIMENTAL_PREFER_TREESITTER, ITreeSitterParserService, ITreeSitterParseResult } from '../../../common/services/treeSitterParserService.js'; +import { EDITOR_EXPERIMENTAL_PREFER_TREESITTER, ITreeSitterParserService, ITreeSitterParseResult, ITextModelTreeSitter } from '../../../common/services/treeSitterParserService.js'; import { IModelService } from '../../../common/services/model.js'; import { Disposable, DisposableMap, DisposableStore, dispose, IDisposable } from '../../../../base/common/lifecycle.js'; import { ITextModel } from '../../../common/model.js'; @@ -31,7 +31,7 @@ function getModuleLocation(environmentService: IEnvironmentService): AppResource return `${(canASAR && environmentService.isBuilt) ? nodeModulesAsarUnpackedPath : nodeModulesPath}/${MODULE_LOCATION_SUBPATH}`; } -export class TextModelTreeSitter extends Disposable { +export class TextModelTreeSitter extends Disposable implements ITextModelTreeSitter { private _onDidChangeParseResult: Emitter = this._register(new Emitter()); public readonly onDidChangeParseResult: Event = this._onDidChangeParseResult.event; private _parseResult: TreeSitterParseResult | undefined; @@ -42,10 +42,15 @@ export class TextModelTreeSitter extends Disposable { private readonly _treeSitterLanguages: TreeSitterLanguages, private readonly _treeSitterImporter: TreeSitterImporter, private readonly _logService: ILogService, - private readonly _telemetryService: ITelemetryService + private readonly _telemetryService: ITelemetryService, + parseImmediately: boolean = true ) { super(); - this._register(Event.runAndSubscribe(this.model.onDidChangeLanguage, (e => this._onDidChangeLanguage(e ? e.newLanguage : this.model.getLanguageId())))); + if (parseImmediately) { + this._register(Event.runAndSubscribe(this.model.onDidChangeLanguage, (e => this._onDidChangeLanguage(e ? e.newLanguage : this.model.getLanguageId())))); + } else { + this._register(this.model.onDidChangeLanguage(e => this._onDidChangeLanguage(e ? e.newLanguage : this.model.getLanguageId()))); + } } private readonly _languageSessionDisposables = this._register(new DisposableStore()); @@ -53,6 +58,10 @@ export class TextModelTreeSitter extends Disposable { * Be very careful when making changes to this method as it is easy to introduce race conditions. */ private async _onDidChangeLanguage(languageId: string) { + this.parse(languageId); + } + + public async parse(languageId: string = this.model.getLanguageId()): Promise { this._languageSessionDisposables.clear(); this._parseResult = undefined; @@ -80,6 +89,7 @@ export class TextModelTreeSitter extends Disposable { } this._parseResult = treeSitterTree; + return this._parseResult; } private _getLanguage(languageId: string, token: CancellationToken): Promise { @@ -459,6 +469,10 @@ export class TreeSitterTextModelService extends Disposable implements ITreeSitte this._modelService.getModels().forEach(model => this._createTextModelTreeSitter(model)); } + public getTextModelTreeSitter(model: ITextModel): ITextModelTreeSitter { + return new TextModelTreeSitter(model, this._treeSitterLanguages, this._treeSitterImporter, this._logService, this._telemetryService, false); + } + private _createTextModelTreeSitter(model: ITextModel) { const textModelTreeSitter = new TextModelTreeSitter(model, this._treeSitterLanguages, this._treeSitterImporter, this._logService, this._telemetryService); const disposables = new DisposableStore(); diff --git a/src/vs/editor/common/languages.ts b/src/vs/editor/common/languages.ts index 12564bcc1e9..9e77c26b74d 100644 --- a/src/vs/editor/common/languages.ts +++ b/src/vs/editor/common/languages.ts @@ -93,6 +93,7 @@ export interface ITreeSitterTokenizationSupport { captureAtPosition(lineNumber: number, column: number, textModel: model.ITextModel): Parser.QueryCapture[]; captureAtPositionTree(lineNumber: number, column: number, tree: Parser.Tree): Parser.QueryCapture[]; onDidChangeTokens: Event<{ textModel: model.ITextModel; changes: IModelTokensChangedEvent }>; + tokenizeEncodedInstrumented(lineNumber: number, textModel: model.ITextModel): { result: Uint32Array; captureTime: number; metadataTime: number } | undefined; } /** diff --git a/src/vs/editor/common/services/treeSitterParserService.ts b/src/vs/editor/common/services/treeSitterParserService.ts index d88b09a6e93..a19f3093be0 100644 --- a/src/vs/editor/common/services/treeSitterParserService.ts +++ b/src/vs/editor/common/services/treeSitterParserService.ts @@ -20,9 +20,21 @@ export interface ITreeSitterParserService { getParseResult(textModel: ITextModel): ITreeSitterParseResult | undefined; getTree(content: string, languageId: string): Promise; onDidUpdateTree: Event<{ textModel: ITextModel; ranges: Range[] }>; + /** + * For testing purposes so that the time to parse can be measured. + */ + getTextModelTreeSitter(textModel: ITextModel): ITextModelTreeSitter | undefined; } export interface ITreeSitterParseResult { readonly tree: Parser.Tree | undefined; readonly language: Parser.Language; } + +export interface ITextModelTreeSitter { + /** + * For testing purposes so that the time to parse can be measured. + */ + parse(languageId?: string): Promise; + dispose(): void; +} diff --git a/src/vs/editor/standalone/browser/standaloneTreeSitterService.ts b/src/vs/editor/standalone/browser/standaloneTreeSitterService.ts index de27e7bea6e..be9b21fbdd9 100644 --- a/src/vs/editor/standalone/browser/standaloneTreeSitterService.ts +++ b/src/vs/editor/standalone/browser/standaloneTreeSitterService.ts @@ -6,7 +6,7 @@ import type { Parser } from '@vscode/tree-sitter-wasm'; import { Event } from '../../../base/common/event.js'; import { ITextModel } from '../../common/model.js'; -import { ITreeSitterParseResult, ITreeSitterParserService } from '../../common/services/treeSitterParserService.js'; +import { ITextModelTreeSitter, ITreeSitterParseResult, ITreeSitterParserService } from '../../common/services/treeSitterParserService.js'; import { Range } from '../../common/core/range.js'; /** @@ -14,6 +14,9 @@ import { Range } from '../../common/core/range.js'; * We use a dummy sertive here to make the build happy. */ export class StandaloneTreeSitterParserService implements ITreeSitterParserService { + getTextModelTreeSitter(textModel: ITextModel): ITextModelTreeSitter | undefined { + return undefined; + } async getTree(content: string, languageId: string): Promise { return undefined; } diff --git a/src/vs/editor/test/common/services/testTreeSitterService.ts b/src/vs/editor/test/common/services/testTreeSitterService.ts index 2d5721bb32f..fd54b59ee5c 100644 --- a/src/vs/editor/test/common/services/testTreeSitterService.ts +++ b/src/vs/editor/test/common/services/testTreeSitterService.ts @@ -6,10 +6,13 @@ import type { Parser } from '@vscode/tree-sitter-wasm'; import { Event } from '../../../../base/common/event.js'; import { ITextModel } from '../../../common/model.js'; -import { ITreeSitterParserService, ITreeSitterParseResult } from '../../../common/services/treeSitterParserService.js'; +import { ITreeSitterParserService, ITreeSitterParseResult, ITextModelTreeSitter } from '../../../common/services/treeSitterParserService.js'; import { Range } from '../../../common/core/range.js'; export class TestTreeSitterParserService implements ITreeSitterParserService { + getTextModelTreeSitter(textModel: ITextModel): ITextModelTreeSitter | undefined { + throw new Error('Method not implemented.'); + } getTree(content: string, languageId: string): Promise { throw new Error('Method not implemented.'); } diff --git a/src/vs/workbench/services/textMate/browser/textMateTokenizationFeature.contribution.ts b/src/vs/workbench/services/textMate/browser/textMateTokenizationFeature.contribution.ts index f0cf742bc70..906ec63bdd8 100644 --- a/src/vs/workbench/services/textMate/browser/textMateTokenizationFeature.contribution.ts +++ b/src/vs/workbench/services/textMate/browser/textMateTokenizationFeature.contribution.ts @@ -7,6 +7,12 @@ import { registerSingleton, InstantiationType } from '../../../../platform/insta import { ITextMateTokenizationService } from './textMateTokenizationFeature.js'; import { TextMateTokenizationFeature } from './textMateTokenizationFeatureImpl.js'; import { IWorkbenchContribution, WorkbenchPhase, registerWorkbenchContribution2 } from '../../../common/contributions.js'; +import { CommandsRegistry } from '../../../../platform/commands/common/commands.js'; +import { ServicesAccessor } from '../../../../editor/browser/editorExtensions.js'; +import { URI } from '../../../../base/common/uri.js'; +import { TokenizationRegistry } from '../../../../editor/common/languages.js'; +import { ITextFileService } from '../../textfile/common/textfiles.js'; +import { StopWatch } from '../../../../base/common/stopwatch.js'; /** * Makes sure the ITextMateTokenizationService is instantiated @@ -23,3 +29,24 @@ class TextMateTokenizationInstantiator implements IWorkbenchContribution { registerSingleton(ITextMateTokenizationService, TextMateTokenizationFeature, InstantiationType.Eager); registerWorkbenchContribution2(TextMateTokenizationInstantiator.ID, TextMateTokenizationInstantiator, WorkbenchPhase.BlockRestore); + +CommandsRegistry.registerCommand('_workbench.colorizeTextMateTokens', async (accessor: ServicesAccessor, resource?: URI): Promise<{ tokenizeTime: number }> => { + const textModelService = accessor.get(ITextFileService); + const textModel = resource ? (await textModelService.files.resolve(resource)).textEditorModel : undefined; + if (!textModel) { + throw new Error(`Cannot resolve text model for resource ${resource}`); + } + + const tokenizer = await TokenizationRegistry.getOrCreate(textModel.getLanguageId()); + if (!tokenizer) { + throw new Error(`Cannot resolve tokenizer for language ${textModel.getLanguageId()}`); + } + + const stopwatch = new StopWatch(); + let state = tokenizer.getInitialState(); + for (let i = 1; i <= textModel.getLineCount(); i++) { + state = tokenizer.tokenizeEncoded(textModel.getLineContent(i), true, state).endState; + } + stopwatch.stop(); + return { tokenizeTime: stopwatch.elapsed() }; +}); diff --git a/src/vs/workbench/services/treeSitter/browser/treeSitterTokenizationFeature.contribution.ts b/src/vs/workbench/services/treeSitter/browser/treeSitterTokenizationFeature.contribution.ts index b6e4a82fc9a..119455c01c5 100644 --- a/src/vs/workbench/services/treeSitter/browser/treeSitterTokenizationFeature.contribution.ts +++ b/src/vs/workbench/services/treeSitter/browser/treeSitterTokenizationFeature.contribution.ts @@ -8,6 +8,12 @@ import { IWorkbenchContribution, WorkbenchPhase, registerWorkbenchContribution2 import { TreeSitterTextModelService } from '../../../../editor/browser/services/treeSitter/treeSitterParserService.js'; import { ITreeSitterParserService } from '../../../../editor/common/services/treeSitterParserService.js'; import { ITreeSitterTokenizationFeature } from './treeSitterTokenizationFeature.js'; +import { ServicesAccessor } from '../../../../platform/instantiation/common/instantiation.js'; +import { CommandsRegistry } from '../../../../platform/commands/common/commands.js'; +import { URI } from '../../../../base/common/uri.js'; +import { TreeSitterTokenizationRegistry } from '../../../../editor/common/languages.js'; +import { ITextFileService } from '../../textfile/common/textfiles.js'; +import { StopWatch } from '../../../../base/common/stopwatch.js'; /** * Makes sure the ITreeSitterTokenizationService is instantiated @@ -25,3 +31,38 @@ class TreeSitterTokenizationInstantiator implements IWorkbenchContribution { registerSingleton(ITreeSitterParserService, TreeSitterTextModelService, InstantiationType.Eager); registerWorkbenchContribution2(TreeSitterTokenizationInstantiator.ID, TreeSitterTokenizationInstantiator, WorkbenchPhase.BlockRestore); + +CommandsRegistry.registerCommand('_workbench.colorizeTreeSitterTokens', async (accessor: ServicesAccessor, resource?: URI): Promise<{ parseTime: number; captureTime: number; metadataTime: number }> => { + const treeSitterParserService = accessor.get(ITreeSitterParserService); + const textModelService = accessor.get(ITextFileService); + const textModel = resource ? (await textModelService.files.resolve(resource)).textEditorModel : undefined; + if (!textModel) { + throw new Error(`Cannot resolve text model for resource ${resource}`); + } + + const tokenizer = await TreeSitterTokenizationRegistry.getOrCreate(textModel.getLanguageId()); + if (!tokenizer) { + throw new Error(`Cannot resolve tokenizer for language ${textModel.getLanguageId()}`); + } + + const textModelTreeSitter = treeSitterParserService.getTextModelTreeSitter(textModel); + if (!textModelTreeSitter) { + throw new Error(`Cannot resolve tree sitter parser for language ${textModel.getLanguageId()}`); + } + const stopwatch = new StopWatch(); + await textModelTreeSitter.parse(); + stopwatch.stop(); + + let captureTime = 0; + let metadataTime = 0; + for (let i = 1; i <= textModel.getLineCount(); i++) { + const result = tokenizer.tokenizeEncodedInstrumented(i, textModel); + if (result) { + captureTime += result.captureTime; + metadataTime += result.metadataTime; + } + } + textModelTreeSitter.dispose(); + textModel.dispose(); + return { parseTime: stopwatch.elapsed(), captureTime, metadataTime }; +}); diff --git a/src/vs/workbench/services/treeSitter/browser/treeSitterTokenizationFeature.ts b/src/vs/workbench/services/treeSitter/browser/treeSitterTokenizationFeature.ts index 0829476700c..0fa967c6b26 100644 --- a/src/vs/workbench/services/treeSitter/browser/treeSitterTokenizationFeature.ts +++ b/src/vs/workbench/services/treeSitter/browser/treeSitterTokenizationFeature.ts @@ -19,6 +19,7 @@ import { createDecorator, IInstantiationService } from '../../../../platform/ins import { IThemeService } from '../../../../platform/theme/common/themeService.js'; import { ColorThemeData, findMetadata } from '../../themes/common/colorThemeData.js'; import { ILanguageService } from '../../../../editor/common/languages/language.js'; +import { StopWatch } from '../../../../base/common/stopwatch.js'; const ALLOWED_SUPPORT = ['typescript']; type TreeSitterQueries = string; @@ -166,6 +167,15 @@ class TreeSitterTokenizationSupport extends Disposable implements ITreeSitterTok * @returns */ public tokenizeEncoded(lineNumber: number, textModel: ITextModel): Uint32Array | undefined { + return this._tokenizeEncoded(lineNumber, textModel)?.result; + } + + public tokenizeEncodedInstrumented(lineNumber: number, textModel: ITextModel): { result: Uint32Array; captureTime: number; metadataTime: number } | undefined { + return this._tokenizeEncoded(lineNumber, textModel); + } + + private _tokenizeEncoded(lineNumber: number, textModel: ITextModel): { result: Uint32Array; captureTime: number; metadataTime: number } | undefined { + const stopwatch = StopWatch.create(); const lineLength = textModel.getLineMaxColumn(lineNumber); const tree = this._getTree(textModel); const captures = this._captureAtRange(lineNumber, new ColumnRange(1, lineLength), tree?.tree); @@ -245,6 +255,8 @@ class TreeSitterTokenizationSupport extends Disposable implements ITreeSitterTok endOffsetsAndScopes[tokenIndex].endOffset = lineLength - 1; tokenIndex++; } + const captureTime = stopwatch.elapsed(); + stopwatch.reset(); const tokens: Uint32Array = new Uint32Array((tokenIndex) * 2); for (let i = 0; i < tokenIndex; i++) { @@ -255,8 +267,8 @@ class TreeSitterTokenizationSupport extends Disposable implements ITreeSitterTok tokens[i * 2] = token.endOffset; tokens[i * 2 + 1] = findMetadata(this._colorThemeData, token.scopes, encodedLanguageId); } - - return tokens; + const metadataTime = stopwatch.elapsed(); + return { result: tokens, captureTime, metadataTime }; } override dispose() {

]: X }, to simply N. This however presumes + // that N distributes over union types, i.e. that N is equivalent to N | N | N. Specifically, we only + // want to perform the reduction when the name type of a mapped type is distributive with respect to the type variable + // introduced by the 'in' clause of the mapped type. Note that non-generic types are considered to be distributive because + // they're the same type regardless of what's being distributed over. + function hasDistributiveNameType(mappedType: MappedType) { + const typeVariable = getTypeParameterFromMappedType(mappedType); + return isDistributive(getNameTypeFromMappedType(mappedType) || typeVariable); + function isDistributive(type: Type): boolean { + return type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Primitive | TypeFlags.Never | TypeFlags.TypeParameter | TypeFlags.Object | TypeFlags.NonPrimitive) ? true : + type.flags & TypeFlags.Conditional ? (type as ConditionalType).root.isDistributive && (type as ConditionalType).checkType === typeVariable : + type.flags & (TypeFlags.UnionOrIntersection | TypeFlags.TemplateLiteral) ? every((type as UnionOrIntersectionType | TemplateLiteralType).types, isDistributive) : + type.flags & TypeFlags.IndexedAccess ? isDistributive((type as IndexedAccessType).objectType) && isDistributive((type as IndexedAccessType).indexType) : + type.flags & TypeFlags.Substitution ? isDistributive((type as SubstitutionType).baseType) && isDistributive((type as SubstitutionType).constraint) : + type.flags & TypeFlags.StringMapping ? isDistributive((type as StringMappingType).type) : + false; + } + } + + function getLiteralTypeFromPropertyName(name: PropertyName | JsxAttributeName) { + if (isPrivateIdentifier(name)) { + return neverType; + } + if (isNumericLiteral(name)) { + return getRegularTypeOfLiteralType(checkExpression(name)); + } + if (isComputedPropertyName(name)) { + return getRegularTypeOfLiteralType(checkComputedPropertyName(name)); + } + const propertyName = getPropertyNameForPropertyNameNode(name); + if (propertyName !== undefined) { + return getStringLiteralType(unescapeLeadingUnderscores(propertyName)); + } + if (isExpression(name)) { + return getRegularTypeOfLiteralType(checkExpression(name)); + } + return neverType; + } + + function getLiteralTypeFromProperty(prop: Symbol, include: TypeFlags, includeNonPublic?: boolean) { + if (includeNonPublic || !(getDeclarationModifierFlagsFromSymbol(prop) & ModifierFlags.NonPublicAccessibilityModifier)) { + let type = getSymbolLinks(getLateBoundSymbol(prop)).nameType; + if (!type) { + const name = getNameOfDeclaration(prop.valueDeclaration) as PropertyName | JsxAttributeName; + type = prop.escapedName === InternalSymbolName.Default ? getStringLiteralType("default") : + name && getLiteralTypeFromPropertyName(name) || (!isKnownSymbol(prop) ? getStringLiteralType(symbolName(prop)) : undefined); + } + if (type && type.flags & include) { + return type; + } + } + return neverType; + } + + function isKeyTypeIncluded(keyType: Type, include: TypeFlags): boolean { + return !!(keyType.flags & include || keyType.flags & TypeFlags.Intersection && some((keyType as IntersectionType).types, t => isKeyTypeIncluded(t, include))); + } + + function getLiteralTypeFromProperties(type: Type, include: TypeFlags, includeOrigin: boolean) { + const origin = includeOrigin && (getObjectFlags(type) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference) || type.aliasSymbol) ? createOriginIndexType(type) : undefined; + const propertyTypes = map(getPropertiesOfType(type), prop => getLiteralTypeFromProperty(prop, include)); + const indexKeyTypes = map(getIndexInfosOfType(type), info => + info !== enumNumberIndexInfo && isKeyTypeIncluded(info.keyType, include) ? + info.keyType === stringType && include & TypeFlags.Number ? stringOrNumberType : info.keyType : neverType); + return getUnionType(concatenate(propertyTypes, indexKeyTypes), UnionReduction.Literal, /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined, origin); + } + + function shouldDeferIndexType(type: Type, indexFlags = IndexFlags.None) { + return !!(type.flags & TypeFlags.InstantiableNonPrimitive || + isGenericTupleType(type) || + isGenericMappedType(type) && (!hasDistributiveNameType(type) || getMappedTypeNameTypeKind(type) === MappedTypeNameTypeKind.Remapping) || + type.flags & TypeFlags.Union && !(indexFlags & IndexFlags.NoReducibleCheck) && isGenericReducibleType(type) || + type.flags & TypeFlags.Intersection && maybeTypeOfKind(type, TypeFlags.Instantiable) && some((type as IntersectionType).types, isEmptyAnonymousObjectType)); + } + + function getIndexType(type: Type, indexFlags = IndexFlags.None): Type { + type = getReducedType(type); + return isNoInferType(type) ? getNoInferType(getIndexType((type as SubstitutionType).baseType, indexFlags)) : + shouldDeferIndexType(type, indexFlags) ? getIndexTypeForGenericType(type as InstantiableType | UnionOrIntersectionType, indexFlags) : + type.flags & TypeFlags.Union ? getIntersectionType(map((type as UnionType).types, t => getIndexType(t, indexFlags))) : + type.flags & TypeFlags.Intersection ? getUnionType(map((type as IntersectionType).types, t => getIndexType(t, indexFlags))) : + getObjectFlags(type) & ObjectFlags.Mapped ? getIndexTypeForMappedType(type as MappedType, indexFlags) : + type === wildcardType ? wildcardType : + type.flags & TypeFlags.Unknown ? neverType : + type.flags & (TypeFlags.Any | TypeFlags.Never) ? stringNumberSymbolType : + getLiteralTypeFromProperties(type, (indexFlags & IndexFlags.NoIndexSignatures ? TypeFlags.StringLiteral : TypeFlags.StringLike) | (indexFlags & IndexFlags.StringsOnly ? 0 : TypeFlags.NumberLike | TypeFlags.ESSymbolLike), indexFlags === IndexFlags.None); + } + + function getExtractStringType(type: Type) { + const extractTypeAlias = getGlobalExtractSymbol(); + return extractTypeAlias ? getTypeAliasInstantiation(extractTypeAlias, [type, stringType]) : stringType; + } + + function getIndexTypeOrString(type: Type): Type { + const indexType = getExtractStringType(getIndexType(type)); + return indexType.flags & TypeFlags.Never ? stringType : indexType; + } + + function getTypeFromTypeOperatorNode(node: TypeOperatorNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + switch (node.operator) { + case SyntaxKind.KeyOfKeyword: + links.resolvedType = getIndexType(getTypeFromTypeNode(node.type)); + break; + case SyntaxKind.UniqueKeyword: + links.resolvedType = node.type.kind === SyntaxKind.SymbolKeyword + ? getESSymbolLikeTypeForNode(walkUpParenthesizedTypes(node.parent)) + : errorType; + break; + case SyntaxKind.ReadonlyKeyword: + links.resolvedType = getTypeFromTypeNode(node.type); + break; + default: + Debug.assertNever(node.operator); + } + } + return links.resolvedType; + } + + function getTypeFromTemplateTypeNode(node: TemplateLiteralTypeNode) { + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getTemplateLiteralType( + [node.head.text, ...map(node.templateSpans, span => span.literal.text)], + map(node.templateSpans, span => getTypeFromTypeNode(span.type)), + ); + } + return links.resolvedType; + } + + function getTemplateLiteralType(texts: readonly string[], types: readonly Type[]): Type { + const unionIndex = findIndex(types, t => !!(t.flags & (TypeFlags.Never | TypeFlags.Union))); + if (unionIndex >= 0) { + return checkCrossProductUnion(types) ? + mapType(types[unionIndex], t => getTemplateLiteralType(texts, replaceElement(types, unionIndex, t))) : + errorType; + } + if (contains(types, wildcardType)) { + return wildcardType; + } + const newTypes: Type[] = []; + const newTexts: string[] = []; + let text = texts[0]; + if (!addSpans(texts, types)) { + return stringType; + } + if (newTypes.length === 0) { + return getStringLiteralType(text); + } + newTexts.push(text); + if (every(newTexts, t => t === "")) { + if (every(newTypes, t => !!(t.flags & TypeFlags.String))) { + return stringType; + } + // Normalize `${Mapping}` into Mapping + if (newTypes.length === 1 && isPatternLiteralType(newTypes[0])) { + return newTypes[0]; + } + } + const id = `${getTypeListId(newTypes)}|${map(newTexts, t => t.length).join(",")}|${newTexts.join("")}`; + let type = templateLiteralTypes.get(id); + if (!type) { + templateLiteralTypes.set(id, type = createTemplateLiteralType(newTexts, newTypes)); + } + return type; + + function addSpans(texts: readonly string[], types: readonly Type[]): boolean { + for (let i = 0; i < types.length; i++) { + const t = types[i]; + if (t.flags & (TypeFlags.Literal | TypeFlags.Null | TypeFlags.Undefined)) { + text += getTemplateStringForType(t) || ""; + text += texts[i + 1]; + } + else if (t.flags & TypeFlags.TemplateLiteral) { + text += (t as TemplateLiteralType).texts[0]; + if (!addSpans((t as TemplateLiteralType).texts, (t as TemplateLiteralType).types)) return false; + text += texts[i + 1]; + } + else if (isGenericIndexType(t) || isPatternLiteralPlaceholderType(t)) { + newTypes.push(t); + newTexts.push(text); + text = texts[i + 1]; + } + else { + return false; + } + } + return true; + } + } + + function getTemplateStringForType(type: Type) { + return type.flags & TypeFlags.StringLiteral ? (type as StringLiteralType).value : + type.flags & TypeFlags.NumberLiteral ? "" + (type as NumberLiteralType).value : + type.flags & TypeFlags.BigIntLiteral ? pseudoBigIntToString((type as BigIntLiteralType).value) : + type.flags & (TypeFlags.BooleanLiteral | TypeFlags.Nullable) ? (type as IntrinsicType).intrinsicName : + undefined; + } + + function createTemplateLiteralType(texts: readonly string[], types: readonly Type[]) { + const type = createType(TypeFlags.TemplateLiteral) as TemplateLiteralType; + type.texts = texts; + type.types = types; + return type; + } + + function getStringMappingType(symbol: Symbol, type: Type): Type { + return type.flags & (TypeFlags.Union | TypeFlags.Never) ? mapType(type, t => getStringMappingType(symbol, t)) : + type.flags & TypeFlags.StringLiteral ? getStringLiteralType(applyStringMapping(symbol, (type as StringLiteralType).value)) : + type.flags & TypeFlags.TemplateLiteral ? getTemplateLiteralType(...applyTemplateStringMapping(symbol, (type as TemplateLiteralType).texts, (type as TemplateLiteralType).types)) : + // Mapping> === Mapping + type.flags & TypeFlags.StringMapping && symbol === type.symbol ? type : + type.flags & (TypeFlags.Any | TypeFlags.String | TypeFlags.StringMapping) || isGenericIndexType(type) ? getStringMappingTypeForGenericType(symbol, type) : + // This handles Mapping<`${number}`> and Mapping<`${bigint}`> + isPatternLiteralPlaceholderType(type) ? getStringMappingTypeForGenericType(symbol, getTemplateLiteralType(["", ""], [type])) : + type; + } + + function applyStringMapping(symbol: Symbol, str: string) { + switch (intrinsicTypeKinds.get(symbol.escapedName as string)) { + case IntrinsicTypeKind.Uppercase: + return str.toUpperCase(); + case IntrinsicTypeKind.Lowercase: + return str.toLowerCase(); + case IntrinsicTypeKind.Capitalize: + return str.charAt(0).toUpperCase() + str.slice(1); + case IntrinsicTypeKind.Uncapitalize: + return str.charAt(0).toLowerCase() + str.slice(1); + } + return str; + } + + function applyTemplateStringMapping(symbol: Symbol, texts: readonly string[], types: readonly Type[]): [texts: readonly string[], types: readonly Type[]] { + switch (intrinsicTypeKinds.get(symbol.escapedName as string)) { + case IntrinsicTypeKind.Uppercase: + return [texts.map(t => t.toUpperCase()), types.map(t => getStringMappingType(symbol, t))]; + case IntrinsicTypeKind.Lowercase: + return [texts.map(t => t.toLowerCase()), types.map(t => getStringMappingType(symbol, t))]; + case IntrinsicTypeKind.Capitalize: + return [texts[0] === "" ? texts : [texts[0].charAt(0).toUpperCase() + texts[0].slice(1), ...texts.slice(1)], texts[0] === "" ? [getStringMappingType(symbol, types[0]), ...types.slice(1)] : types]; + case IntrinsicTypeKind.Uncapitalize: + return [texts[0] === "" ? texts : [texts[0].charAt(0).toLowerCase() + texts[0].slice(1), ...texts.slice(1)], texts[0] === "" ? [getStringMappingType(symbol, types[0]), ...types.slice(1)] : types]; + } + return [texts, types]; + } + + function getStringMappingTypeForGenericType(symbol: Symbol, type: Type): Type { + const id = `${getSymbolId(symbol)},${getTypeId(type)}`; + let result = stringMappingTypes.get(id); + if (!result) { + stringMappingTypes.set(id, result = createStringMappingType(symbol, type)); + } + return result; + } + + function createStringMappingType(symbol: Symbol, type: Type) { + const result = createTypeWithSymbol(TypeFlags.StringMapping, symbol) as StringMappingType; + result.type = type; + return result; + } + + function createIndexedAccessType(objectType: Type, indexType: Type, accessFlags: AccessFlags, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { + const type = createType(TypeFlags.IndexedAccess) as IndexedAccessType; + type.objectType = objectType; + type.indexType = indexType; + type.accessFlags = accessFlags; + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = aliasTypeArguments; + return type; + } + + /** + * Returns if a type is or consists of a JSLiteral object type + * In addition to objects which are directly literals, + * * unions where every element is a jsliteral + * * intersections where at least one element is a jsliteral + * * and instantiable types constrained to a jsliteral + * Should all count as literals and not print errors on access or assignment of possibly existing properties. + * This mirrors the behavior of the index signature propagation, to which this behaves similarly (but doesn't affect assignability or inference). + */ + function isJSLiteralType(type: Type): boolean { + if (noImplicitAny) { + return false; // Flag is meaningless under `noImplicitAny` mode + } + if (getObjectFlags(type) & ObjectFlags.JSLiteral) { + return true; + } + if (type.flags & TypeFlags.Union) { + return every((type as UnionType).types, isJSLiteralType); + } + if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, isJSLiteralType); + } + if (type.flags & TypeFlags.Instantiable) { + const constraint = getResolvedBaseConstraint(type); + return constraint !== type && isJSLiteralType(constraint); + } + return false; + } + + function getPropertyNameFromIndex(indexType: Type, accessNode: PropertyName | ObjectBindingPattern | ArrayBindingPattern | IndexedAccessTypeNode | ElementAccessExpression | SyntheticExpression | undefined) { + return isTypeUsableAsPropertyName(indexType) ? + getPropertyNameFromType(indexType) : + accessNode && isPropertyName(accessNode) ? + // late bound names are handled in the first branch, so here we only need to handle normal names + getPropertyNameForPropertyNameNode(accessNode) : + undefined; + } + + function isUncalledFunctionReference(node: Node, symbol: Symbol) { + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method)) { + const parent = findAncestor(node.parent, n => !isAccessExpression(n)) || node.parent; + if (isCallLikeExpression(parent)) { + return isCallOrNewExpression(parent) && isIdentifier(node) && hasMatchingArgument(parent, node); + } + return every(symbol.declarations, d => !isFunctionLike(d) || isDeprecatedDeclaration(d)); + } + return true; + } + + function getPropertyTypeForIndexType(originalObjectType: Type, objectType: Type, indexType: Type, fullIndexType: Type, accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression | undefined, accessFlags: AccessFlags) { + const accessExpression = accessNode && accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode : undefined; + const propName = accessNode && isPrivateIdentifier(accessNode) ? undefined : getPropertyNameFromIndex(indexType, accessNode); + + if (propName !== undefined) { + if (accessFlags & AccessFlags.Contextual) { + return getTypeOfPropertyOfContextualType(objectType, propName) || anyType; + } + const prop = getPropertyOfType(objectType, propName); + if (prop) { + if (accessFlags & AccessFlags.ReportDeprecated && accessNode && prop.declarations && isDeprecatedSymbol(prop) && isUncalledFunctionReference(accessNode, prop)) { + const deprecatedNode = accessExpression?.argumentExpression ?? (isIndexedAccessTypeNode(accessNode) ? accessNode.indexType : accessNode); + addDeprecatedSuggestion(deprecatedNode, prop.declarations, propName as string); + } + if (accessExpression) { + markPropertyAsReferenced(prop, accessExpression, isSelfTypeAccess(accessExpression.expression, objectType.symbol)); + if (isAssignmentToReadonlyEntity(accessExpression, prop, getAssignmentTargetKind(accessExpression))) { + error(accessExpression.argumentExpression, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(prop)); + return undefined; + } + if (accessFlags & AccessFlags.CacheSymbol) { + getNodeLinks(accessNode!).resolvedSymbol = prop; + } + if (isThisPropertyAccessInConstructor(accessExpression, prop)) { + return autoType; + } + } + const propType = accessFlags & AccessFlags.Writing ? getWriteTypeOfSymbol(prop) : getTypeOfSymbol(prop); + return accessExpression && getAssignmentTargetKind(accessExpression) !== AssignmentKind.Definite ? getFlowTypeOfReference(accessExpression, propType) : + accessNode && isIndexedAccessTypeNode(accessNode) && containsMissingType(propType) ? getUnionType([propType, undefinedType]) : + propType; + } + if (everyType(objectType, isTupleType) && isNumericLiteralName(propName)) { + const index = +propName; + if (accessNode && everyType(objectType, t => !((t as TupleTypeReference).target.combinedFlags & ElementFlags.Variable)) && !(accessFlags & AccessFlags.NoTupleBoundsCheck)) { + const indexNode = getIndexNodeForAccessExpression(accessNode); + if (isTupleType(objectType)) { + if (index < 0) { + error(indexNode, Diagnostics.A_tuple_type_cannot_be_indexed_with_a_negative_value); + return undefinedType; + } + error(indexNode, Diagnostics.Tuple_type_0_of_length_1_has_no_element_at_index_2, typeToString(objectType), getTypeReferenceArity(objectType), unescapeLeadingUnderscores(propName)); + } + else { + error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType)); + } + } + if (index >= 0) { + errorIfWritingToReadonlyIndex(getIndexInfoOfType(objectType, numberType)); + return getTupleElementTypeOutOfStartCount(objectType, index, accessFlags & AccessFlags.IncludeUndefined ? missingType : undefined); + } + } + } + if (!(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike)) { + if (objectType.flags & (TypeFlags.Any | TypeFlags.Never)) { + return objectType; + } + // If no index signature is applicable, we default to the string index signature. In effect, this means the string + // index signature applies even when accessing with a symbol-like type. + const indexInfo = getApplicableIndexInfo(objectType, indexType) || getIndexInfoOfType(objectType, stringType); + if (indexInfo) { + if (accessFlags & AccessFlags.NoIndexSignatures && indexInfo.keyType !== numberType) { + if (accessExpression) { + if (accessFlags & AccessFlags.Writing) { + error(accessExpression, Diagnostics.Type_0_is_generic_and_can_only_be_indexed_for_reading, typeToString(originalObjectType)); + } + else { + error(accessExpression, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(originalObjectType)); + } + } + return undefined; + } + if (accessNode && indexInfo.keyType === stringType && !isTypeAssignableToKind(indexType, TypeFlags.String | TypeFlags.Number)) { + const indexNode = getIndexNodeForAccessExpression(accessNode); + error(indexNode, Diagnostics.Type_0_cannot_be_used_as_an_index_type, typeToString(indexType)); + return accessFlags & AccessFlags.IncludeUndefined ? getUnionType([indexInfo.type, missingType]) : indexInfo.type; + } + errorIfWritingToReadonlyIndex(indexInfo); + // When accessing an enum object with its own type, + // e.g. E[E.A] for enum E { A }, undefined shouldn't + // be included in the result type + if ( + (accessFlags & AccessFlags.IncludeUndefined) && + !(objectType.symbol && + objectType.symbol.flags & (SymbolFlags.RegularEnum | SymbolFlags.ConstEnum) && + (indexType.symbol && + indexType.flags & TypeFlags.EnumLiteral && + getParentOfSymbol(indexType.symbol) === objectType.symbol)) + ) { + return getUnionType([indexInfo.type, missingType]); + } + return indexInfo.type; + } + if (indexType.flags & TypeFlags.Never) { + return neverType; + } + if (isJSLiteralType(objectType)) { + return anyType; + } + if (accessExpression && !isConstEnumObjectType(objectType)) { + if (isObjectLiteralType(objectType)) { + if (noImplicitAny && indexType.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) { + diagnostics.add(createDiagnosticForNode(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as StringLiteralType).value, typeToString(objectType))); + return undefinedType; + } + else if (indexType.flags & (TypeFlags.Number | TypeFlags.String)) { + const types = map((objectType as ResolvedType).properties, property => { + return getTypeOfSymbol(property); + }); + return getUnionType(append(types, undefinedType)); + } + } + + if (objectType.symbol === globalThisSymbol && propName !== undefined && globalThisSymbol.exports!.has(propName) && (globalThisSymbol.exports!.get(propName)!.flags & SymbolFlags.BlockScoped)) { + error(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType)); + } + else if (noImplicitAny && !(accessFlags & AccessFlags.SuppressNoImplicitAnyError)) { + if (propName !== undefined && typeHasStaticProperty(propName, objectType)) { + const typeName = typeToString(objectType); + error(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_to_access_the_static_member_2_instead, propName as string, typeName, typeName + "[" + getTextOfNode(accessExpression.argumentExpression) + "]"); + } + else if (getIndexTypeOfType(objectType, numberType)) { + error(accessExpression.argumentExpression, Diagnostics.Element_implicitly_has_an_any_type_because_index_expression_is_not_of_type_number); + } + else { + let suggestion: string | undefined; + if (propName !== undefined && (suggestion = getSuggestionForNonexistentProperty(propName as string, objectType))) { + if (suggestion !== undefined) { + error(accessExpression.argumentExpression, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2, propName as string, typeToString(objectType), suggestion); + } + } + else { + const suggestion = getSuggestionForNonexistentIndexSignature(objectType, accessExpression, indexType); + if (suggestion !== undefined) { + error(accessExpression, Diagnostics.Element_implicitly_has_an_any_type_because_type_0_has_no_index_signature_Did_you_mean_to_call_1, typeToString(objectType), suggestion); + } + else { + let errorInfo: DiagnosticMessageChain | undefined; + if (indexType.flags & TypeFlags.EnumLiteral) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, "[" + typeToString(indexType) + "]", typeToString(objectType)); + } + else if (indexType.flags & TypeFlags.UniqueESSymbol) { + const symbolName = getFullyQualifiedName((indexType as UniqueESSymbolType).symbol, accessExpression); + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, "[" + symbolName + "]", typeToString(objectType)); + } + else if (indexType.flags & TypeFlags.StringLiteral) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as StringLiteralType).value, typeToString(objectType)); + } + else if (indexType.flags & TypeFlags.NumberLiteral) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as NumberLiteralType).value, typeToString(objectType)); + } + else if (indexType.flags & (TypeFlags.Number | TypeFlags.String)) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_index_signature_with_a_parameter_of_type_0_was_found_on_type_1, typeToString(indexType), typeToString(objectType)); + } + + errorInfo = chainDiagnosticMessages( + errorInfo, + Diagnostics.Element_implicitly_has_an_any_type_because_expression_of_type_0_can_t_be_used_to_index_type_1, + typeToString(fullIndexType), + typeToString(objectType), + ); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(accessExpression), accessExpression, errorInfo)); + } + } + } + } + return undefined; + } + } + if (isJSLiteralType(objectType)) { + return anyType; + } + if (accessNode) { + const indexNode = getIndexNodeForAccessExpression(accessNode); + if (indexType.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) { + error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, "" + (indexType as StringLiteralType | NumberLiteralType).value, typeToString(objectType)); + } + else if (indexType.flags & (TypeFlags.String | TypeFlags.Number)) { + error(indexNode, Diagnostics.Type_0_has_no_matching_index_signature_for_type_1, typeToString(objectType), typeToString(indexType)); + } + else { + error(indexNode, Diagnostics.Type_0_cannot_be_used_as_an_index_type, typeToString(indexType)); + } + } + if (isTypeAny(indexType)) { + return indexType; + } + return undefined; + + function errorIfWritingToReadonlyIndex(indexInfo: IndexInfo | undefined): void { + if (indexInfo && indexInfo.isReadonly && accessExpression && (isAssignmentTarget(accessExpression) || isDeleteTarget(accessExpression))) { + error(accessExpression, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType)); + } + } + } + + function getIndexNodeForAccessExpression(accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression) { + return accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode.argumentExpression : + accessNode.kind === SyntaxKind.IndexedAccessType ? accessNode.indexType : + accessNode.kind === SyntaxKind.ComputedPropertyName ? accessNode.expression : + accessNode; + } + + function isPatternLiteralPlaceholderType(type: Type): boolean { + if (type.flags & TypeFlags.Intersection) { + // Return true if the intersection consists of one or more placeholders and zero or + // more object type tags. + let seenPlaceholder = false; + for (const t of (type as IntersectionType).types) { + if (t.flags & (TypeFlags.Literal | TypeFlags.Nullable) || isPatternLiteralPlaceholderType(t)) { + seenPlaceholder = true; + } + else if (!(t.flags & TypeFlags.Object)) { + return false; + } + } + return seenPlaceholder; + } + return !!(type.flags & (TypeFlags.Any | TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt)) || isPatternLiteralType(type); + } + + function isPatternLiteralType(type: Type) { + // A pattern literal type is a template literal or a string mapping type that contains only + // non-generic pattern literal placeholders. + return !!(type.flags & TypeFlags.TemplateLiteral) && every((type as TemplateLiteralType).types, isPatternLiteralPlaceholderType) || + !!(type.flags & TypeFlags.StringMapping) && isPatternLiteralPlaceholderType((type as StringMappingType).type); + } + + function isGenericStringLikeType(type: Type) { + return !!(type.flags & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping)) && !isPatternLiteralType(type); + } + + function isGenericType(type: Type): boolean { + return !!getGenericObjectFlags(type); + } + + function isGenericObjectType(type: Type): boolean { + return !!(getGenericObjectFlags(type) & ObjectFlags.IsGenericObjectType); + } + + function isGenericIndexType(type: Type): boolean { + return !!(getGenericObjectFlags(type) & ObjectFlags.IsGenericIndexType); + } + + function getGenericObjectFlags(type: Type): ObjectFlags { + if (type.flags & (TypeFlags.UnionOrIntersection)) { + if (!((type as UnionOrIntersectionType).objectFlags & ObjectFlags.IsGenericTypeComputed)) { + (type as UnionOrIntersectionType).objectFlags |= ObjectFlags.IsGenericTypeComputed | + reduceLeft((type as UnionOrIntersectionType).types, (flags, t) => flags | getGenericObjectFlags(t), 0); + } + return (type as UnionOrIntersectionType).objectFlags & ObjectFlags.IsGenericType; + } + if (type.flags & TypeFlags.Substitution) { + if (!((type as SubstitutionType).objectFlags & ObjectFlags.IsGenericTypeComputed)) { + (type as SubstitutionType).objectFlags |= ObjectFlags.IsGenericTypeComputed | + getGenericObjectFlags((type as SubstitutionType).baseType) | getGenericObjectFlags((type as SubstitutionType).constraint); + } + return (type as SubstitutionType).objectFlags & ObjectFlags.IsGenericType; + } + return (type.flags & TypeFlags.InstantiableNonPrimitive || isGenericMappedType(type) || isGenericTupleType(type) ? ObjectFlags.IsGenericObjectType : 0) | + (type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.Index) || isGenericStringLikeType(type) ? ObjectFlags.IsGenericIndexType : 0); + } + + function getSimplifiedType(type: Type, writing: boolean): Type { + return type.flags & TypeFlags.IndexedAccess ? getSimplifiedIndexedAccessType(type as IndexedAccessType, writing) : + type.flags & TypeFlags.Conditional ? getSimplifiedConditionalType(type as ConditionalType, writing) : + type; + } + + function distributeIndexOverObjectType(objectType: Type, indexType: Type, writing: boolean) { + // (T | U)[K] -> T[K] | U[K] (reading) + // (T | U)[K] -> T[K] & U[K] (writing) + // (T & U)[K] -> T[K] & U[K] + if (objectType.flags & TypeFlags.Union || objectType.flags & TypeFlags.Intersection && !shouldDeferIndexType(objectType)) { + const types = map((objectType as UnionOrIntersectionType).types, t => getSimplifiedType(getIndexedAccessType(t, indexType), writing)); + return objectType.flags & TypeFlags.Intersection || writing ? getIntersectionType(types) : getUnionType(types); + } + } + + function distributeObjectOverIndexType(objectType: Type, indexType: Type, writing: boolean) { + // T[A | B] -> T[A] | T[B] (reading) + // T[A | B] -> T[A] & T[B] (writing) + if (indexType.flags & TypeFlags.Union) { + const types = map((indexType as UnionType).types, t => getSimplifiedType(getIndexedAccessType(objectType, t), writing)); + return writing ? getIntersectionType(types) : getUnionType(types); + } + } + + // Transform an indexed access to a simpler form, if possible. Return the simpler form, or return + // the type itself if no transformation is possible. The writing flag indicates that the type is + // the target of an assignment. + function getSimplifiedIndexedAccessType(type: IndexedAccessType, writing: boolean): Type { + const cache = writing ? "simplifiedForWriting" : "simplifiedForReading"; + if (type[cache]) { + return type[cache] === circularConstraintType ? type : type[cache]!; + } + type[cache] = circularConstraintType; + // We recursively simplify the object type as it may in turn be an indexed access type. For example, with + // '{ [P in T]: { [Q in U]: number } }[T][U]' we want to first simplify the inner indexed access type. + const objectType = getSimplifiedType(type.objectType, writing); + const indexType = getSimplifiedType(type.indexType, writing); + // T[A | B] -> T[A] | T[B] (reading) + // T[A | B] -> T[A] & T[B] (writing) + const distributedOverIndex = distributeObjectOverIndexType(objectType, indexType, writing); + if (distributedOverIndex) { + return type[cache] = distributedOverIndex; + } + // Only do the inner distributions if the index can no longer be instantiated to cause index distribution again + if (!(indexType.flags & TypeFlags.Instantiable)) { + // (T | U)[K] -> T[K] | U[K] (reading) + // (T | U)[K] -> T[K] & U[K] (writing) + // (T & U)[K] -> T[K] & U[K] + const distributedOverObject = distributeIndexOverObjectType(objectType, indexType, writing); + if (distributedOverObject) { + return type[cache] = distributedOverObject; + } + } + // So ultimately (reading): + // ((A & B) | C)[K1 | K2] -> ((A & B) | C)[K1] | ((A & B) | C)[K2] -> (A & B)[K1] | C[K1] | (A & B)[K2] | C[K2] -> (A[K1] & B[K1]) | C[K1] | (A[K2] & B[K2]) | C[K2] + + // A generic tuple type indexed by a number exists only when the index type doesn't select a + // fixed element. We simplify to either the combined type of all elements (when the index type + // the actual number type) or to the combined type of all non-fixed elements. + if (isGenericTupleType(objectType) && indexType.flags & TypeFlags.NumberLike) { + const elementType = getElementTypeOfSliceOfTupleType(objectType, indexType.flags & TypeFlags.Number ? 0 : objectType.target.fixedLength, /*endSkipCount*/ 0, writing); + if (elementType) { + return type[cache] = elementType; + } + } + // If the object type is a mapped type { [P in K]: E }, where K is generic, or { [P in K as N]: E }, where + // K is generic and N is assignable to P, instantiate E using a mapper that substitutes the index type for P. + // For example, for an index access { [P in K]: Box }[X], we construct the type Box. + if (isGenericMappedType(objectType)) { + if (getMappedTypeNameTypeKind(objectType) !== MappedTypeNameTypeKind.Remapping) { + return type[cache] = mapType(substituteIndexedMappedType(objectType, type.indexType), t => getSimplifiedType(t, writing)); + } + } + return type[cache] = type; + } + + function getSimplifiedConditionalType(type: ConditionalType, writing: boolean) { + const checkType = type.checkType; + const extendsType = type.extendsType; + const trueType = getTrueTypeFromConditionalType(type); + const falseType = getFalseTypeFromConditionalType(type); + // Simplifications for types of the form `T extends U ? T : never` and `T extends U ? never : T`. + if (falseType.flags & TypeFlags.Never && getActualTypeVariable(trueType) === getActualTypeVariable(checkType)) { + if (checkType.flags & TypeFlags.Any || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true + return getSimplifiedType(trueType, writing); + } + else if (isIntersectionEmpty(checkType, extendsType)) { // Always false + return neverType; + } + } + else if (trueType.flags & TypeFlags.Never && getActualTypeVariable(falseType) === getActualTypeVariable(checkType)) { + if (!(checkType.flags & TypeFlags.Any) && isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true + return neverType; + } + else if (checkType.flags & TypeFlags.Any || isIntersectionEmpty(checkType, extendsType)) { // Always false + return getSimplifiedType(falseType, writing); + } + } + return type; + } + + /** + * Invokes union simplification logic to determine if an intersection is considered empty as a union constituent + */ + function isIntersectionEmpty(type1: Type, type2: Type) { + return !!(getUnionType([intersectTypes(type1, type2), neverType]).flags & TypeFlags.Never); + } + + // Given an indexed access on a mapped type of the form { [P in K]: E }[X], return an instantiation of E where P is + // replaced with X. Since this simplification doesn't account for mapped type modifiers, add 'undefined' to the + // resulting type if the mapped type includes a '?' modifier or if the modifiers type indicates that some properties + // are optional. If the modifiers type is generic, conservatively estimate optionality by recursively looking for + // mapped types that include '?' modifiers. + function substituteIndexedMappedType(objectType: MappedType, index: Type) { + const mapper = createTypeMapper([getTypeParameterFromMappedType(objectType)], [index]); + const templateMapper = combineTypeMappers(objectType.mapper, mapper); + const instantiatedTemplateType = instantiateType(getTemplateTypeFromMappedType(objectType.target as MappedType || objectType), templateMapper); + const isOptional = getMappedTypeOptionality(objectType) > 0 || (isGenericType(objectType) ? + getCombinedMappedTypeOptionality(getModifiersTypeFromMappedType(objectType)) > 0 : + couldAccessOptionalProperty(objectType, index)); + return addOptionality(instantiatedTemplateType, /*isProperty*/ true, isOptional); + } + + // Return true if an indexed access with the given object and index types could access an optional property. + function couldAccessOptionalProperty(objectType: Type, indexType: Type) { + const indexConstraint = getBaseConstraintOfType(indexType); + return !!indexConstraint && some(getPropertiesOfType(objectType), p => + !!(p.flags & SymbolFlags.Optional) && + isTypeAssignableTo(getLiteralTypeFromProperty(p, TypeFlags.StringOrNumberLiteralOrUnique), indexConstraint)); + } + + function getIndexedAccessType(objectType: Type, indexType: Type, accessFlags = AccessFlags.None, accessNode?: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + return getIndexedAccessTypeOrUndefined(objectType, indexType, accessFlags, accessNode, aliasSymbol, aliasTypeArguments) || (accessNode ? errorType : unknownType); + } + + function indexTypeLessThan(indexType: Type, limit: number) { + return everyType(indexType, t => { + if (t.flags & TypeFlags.StringOrNumberLiteral) { + const propName = getPropertyNameFromType(t as StringLiteralType | NumberLiteralType); + if (isNumericLiteralName(propName)) { + const index = +propName; + return index >= 0 && index < limit; + } + } + return false; + }); + } + + function getIndexedAccessTypeOrUndefined(objectType: Type, indexType: Type, accessFlags = AccessFlags.None, accessNode?: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type | undefined { + if (objectType === wildcardType || indexType === wildcardType) { + return wildcardType; + } + objectType = getReducedType(objectType); + // If the object type has a string index signature and no other members we know that the result will + // always be the type of that index signature and we can simplify accordingly. + if (isStringIndexSignatureOnlyType(objectType) && !(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.String | TypeFlags.Number)) { + indexType = stringType; + } + // In noUncheckedIndexedAccess mode, indexed access operations that occur in an expression in a read position and resolve to + // an index signature have 'undefined' included in their type. + if (compilerOptions.noUncheckedIndexedAccess && accessFlags & AccessFlags.ExpressionPosition) accessFlags |= AccessFlags.IncludeUndefined; + // If the index type is generic, or if the object type is generic and doesn't originate in an expression and + // the operation isn't exclusively indexing the fixed (non-variadic) portion of a tuple type, we are performing + // a higher-order index access where we cannot meaningfully access the properties of the object type. Note that + // for a generic T and a non-generic K, we eagerly resolve T[K] if it originates in an expression. This is to + // preserve backwards compatibility. For example, an element access 'this["foo"]' has always been resolved + // eagerly using the constraint type of 'this' at the given location. + if ( + isGenericIndexType(indexType) || (accessNode && accessNode.kind !== SyntaxKind.IndexedAccessType ? + isGenericTupleType(objectType) && !indexTypeLessThan(indexType, getTotalFixedElementCount(objectType.target)) : + isGenericObjectType(objectType) && !(isTupleType(objectType) && indexTypeLessThan(indexType, getTotalFixedElementCount(objectType.target))) || isGenericReducibleType(objectType)) + ) { + if (objectType.flags & TypeFlags.AnyOrUnknown) { + return objectType; + } + // Defer the operation by creating an indexed access type. + const persistentAccessFlags = accessFlags & AccessFlags.Persistent; + const id = objectType.id + "," + indexType.id + "," + persistentAccessFlags + getAliasId(aliasSymbol, aliasTypeArguments); + let type = indexedAccessTypes.get(id); + if (!type) { + indexedAccessTypes.set(id, type = createIndexedAccessType(objectType, indexType, persistentAccessFlags, aliasSymbol, aliasTypeArguments)); + } + + return type; + } + // In the following we resolve T[K] to the type of the property in T selected by K. + // We treat boolean as different from other unions to improve errors; + // skipping straight to getPropertyTypeForIndexType gives errors with 'boolean' instead of 'true'. + const apparentObjectType = getReducedApparentType(objectType); + if (indexType.flags & TypeFlags.Union && !(indexType.flags & TypeFlags.Boolean)) { + const propTypes: Type[] = []; + let wasMissingProp = false; + for (const t of (indexType as UnionType).types) { + const propType = getPropertyTypeForIndexType(objectType, apparentObjectType, t, indexType, accessNode, accessFlags | (wasMissingProp ? AccessFlags.SuppressNoImplicitAnyError : 0)); + if (propType) { + propTypes.push(propType); + } + else if (!accessNode) { + // If there's no error node, we can immeditely stop, since error reporting is off + return undefined; + } + else { + // Otherwise we set a flag and return at the end of the loop so we still mark all errors + wasMissingProp = true; + } + } + if (wasMissingProp) { + return undefined; + } + return accessFlags & AccessFlags.Writing + ? getIntersectionType(propTypes, IntersectionFlags.None, aliasSymbol, aliasTypeArguments) + : getUnionType(propTypes, UnionReduction.Literal, aliasSymbol, aliasTypeArguments); + } + return getPropertyTypeForIndexType(objectType, apparentObjectType, indexType, indexType, accessNode, accessFlags | AccessFlags.CacheSymbol | AccessFlags.ReportDeprecated); + } + + function getTypeFromIndexedAccessTypeNode(node: IndexedAccessTypeNode) { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const objectType = getTypeFromTypeNode(node.objectType); + const indexType = getTypeFromTypeNode(node.indexType); + const potentialAlias = getAliasSymbolForTypeNode(node); + links.resolvedType = getIndexedAccessType(objectType, indexType, AccessFlags.None, node, potentialAlias, getTypeArgumentsForAliasSymbol(potentialAlias)); + } + return links.resolvedType; + } + + function getTypeFromMappedTypeNode(node: MappedTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const type = createObjectType(ObjectFlags.Mapped, node.symbol) as MappedType; + type.declaration = node; + type.aliasSymbol = getAliasSymbolForTypeNode(node); + type.aliasTypeArguments = getTypeArgumentsForAliasSymbol(type.aliasSymbol); + links.resolvedType = type; + // Eagerly resolve the constraint type which forces an error if the constraint type circularly + // references itself through one or more type aliases. + getConstraintTypeFromMappedType(type); + } + return links.resolvedType; + } + + function getActualTypeVariable(type: Type): Type { + if (type.flags & TypeFlags.Substitution) { + return getActualTypeVariable((type as SubstitutionType).baseType); + } + if ( + type.flags & TypeFlags.IndexedAccess && ( + (type as IndexedAccessType).objectType.flags & TypeFlags.Substitution || + (type as IndexedAccessType).indexType.flags & TypeFlags.Substitution + ) + ) { + return getIndexedAccessType(getActualTypeVariable((type as IndexedAccessType).objectType), getActualTypeVariable((type as IndexedAccessType).indexType)); + } + return type; + } + + function isSimpleTupleType(node: TypeNode): boolean { + return isTupleTypeNode(node) && length(node.elements) > 0 && + !some(node.elements, e => isOptionalTypeNode(e) || isRestTypeNode(e) || isNamedTupleMember(e) && !!(e.questionToken || e.dotDotDotToken)); + } + + function isDeferredType(type: Type, checkTuples: boolean) { + return isGenericType(type) || checkTuples && isTupleType(type) && some(getElementTypes(type), isGenericType); + } + + function getConditionalType(root: ConditionalRoot, mapper: TypeMapper | undefined, forConstraint: boolean, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + let result; + let extraTypes: Type[] | undefined; + let tailCount = 0; + // We loop here for an immediately nested conditional type in the false position, effectively treating + // types of the form 'A extends B ? X : C extends D ? Y : E extends F ? Z : ...' as a single construct for + // purposes of resolution. We also loop here when resolution of a conditional type ends in resolution of + // another (or, through recursion, possibly the same) conditional type. In the potentially tail-recursive + // cases we increment the tail recursion counter and stop after 1000 iterations. + while (true) { + if (tailCount === 1000) { + error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite); + return errorType; + } + const checkType = instantiateType(getActualTypeVariable(root.checkType), mapper); + const extendsType = instantiateType(root.extendsType, mapper); + if (checkType === errorType || extendsType === errorType) { + return errorType; + } + if (checkType === wildcardType || extendsType === wildcardType) { + return wildcardType; + } + const checkTypeNode = skipTypeParentheses(root.node.checkType); + const extendsTypeNode = skipTypeParentheses(root.node.extendsType); + // When the check and extends types are simple tuple types of the same arity, we defer resolution of the + // conditional type when any tuple elements are generic. This is such that non-distributable conditional + // types can be written `[X] extends [Y] ? ...` and be deferred similarly to `X extends Y ? ...`. + const checkTuples = isSimpleTupleType(checkTypeNode) && isSimpleTupleType(extendsTypeNode) && + length((checkTypeNode as TupleTypeNode).elements) === length((extendsTypeNode as TupleTypeNode).elements); + const checkTypeDeferred = isDeferredType(checkType, checkTuples); + let combinedMapper: TypeMapper | undefined; + if (root.inferTypeParameters) { + // When we're looking at making an inference for an infer type, when we get its constraint, it'll automagically be + // instantiated with the context, so it doesn't need the mapper for the inference context - however the constraint + // may refer to another _root_, _uncloned_ `infer` type parameter [1], or to something mapped by `mapper` [2]. + // [1] Eg, if we have `Foo` and `Foo` - `B` is constrained to `T`, which, in turn, has been instantiated + // as `number` + // Conversely, if we have `Foo`, `B` is still constrained to `T` and `T` is instantiated as `A` + // [2] Eg, if we have `Foo` and `Foo` where `Q` is mapped by `mapper` into `number` - `B` is constrained to `T` + // which is in turn instantiated as `Q`, which is in turn instantiated as `number`. + // So we need to: + // * combine `context.nonFixingMapper` with `mapper` so their constraints can be instantiated in the context of `mapper` (otherwise they'd only get inference context information) + // * incorporate all of the component mappers into the combined mapper for the true and false members + // This means we have two mappers that need applying: + // * The original `mapper` used to create this conditional + // * The mapper that maps the infer type parameter to its inference result (`context.mapper`) + const context = createInferenceContext(root.inferTypeParameters, /*signature*/ undefined, InferenceFlags.None); + if (mapper) { + context.nonFixingMapper = combineTypeMappers(context.nonFixingMapper, mapper); + } + if (!checkTypeDeferred) { + // We don't want inferences from constraints as they may cause us to eagerly resolve the + // conditional type instead of deferring resolution. Also, we always want strict function + // types rules (i.e. proper contravariance) for inferences. + inferTypes(context.inferences, checkType, extendsType, InferencePriority.NoConstraints | InferencePriority.AlwaysStrict); + } + // It's possible for 'infer T' type paramteters to be given uninstantiated constraints when the + // those type parameters are used in type references (see getInferredTypeParameterConstraint). For + // that reason we need context.mapper to be first in the combined mapper. See #42636 for examples. + combinedMapper = mapper ? combineTypeMappers(context.mapper, mapper) : context.mapper; + } + // Instantiate the extends type including inferences for 'infer T' type parameters + const inferredExtendsType = combinedMapper ? instantiateType(root.extendsType, combinedMapper) : extendsType; + // We attempt to resolve the conditional type only when the check and extends types are non-generic + if (!checkTypeDeferred && !isDeferredType(inferredExtendsType, checkTuples)) { + // Return falseType for a definitely false extends check. We check an instantiations of the two + // types with type parameters mapped to the wildcard type, the most permissive instantiations + // possible (the wildcard type is assignable to and from all types). If those are not related, + // then no instantiations will be and we can just return the false branch type. + if (!(inferredExtendsType.flags & TypeFlags.AnyOrUnknown) && (checkType.flags & TypeFlags.Any || !isTypeAssignableTo(getPermissiveInstantiation(checkType), getPermissiveInstantiation(inferredExtendsType)))) { + // Return union of trueType and falseType for 'any' since it matches anything. Furthermore, for a + // distributive conditional type applied to the constraint of a type variable, include trueType if + // there are possible values of the check type that are also possible values of the extends type. + // We use a reverse assignability check as it is less expensive than the comparable relationship + // and avoids false positives of a non-empty intersection check. + if (checkType.flags & TypeFlags.Any || forConstraint && !(inferredExtendsType.flags & TypeFlags.Never) && someType(getPermissiveInstantiation(inferredExtendsType), t => isTypeAssignableTo(t, getPermissiveInstantiation(checkType)))) { + (extraTypes || (extraTypes = [])).push(instantiateType(getTypeFromTypeNode(root.node.trueType), combinedMapper || mapper)); + } + // If falseType is an immediately nested conditional type that isn't distributive or has an + // identical checkType, switch to that type and loop. + const falseType = getTypeFromTypeNode(root.node.falseType); + if (falseType.flags & TypeFlags.Conditional) { + const newRoot = (falseType as ConditionalType).root; + if (newRoot.node.parent === root.node && (!newRoot.isDistributive || newRoot.checkType === root.checkType)) { + root = newRoot; + continue; + } + if (canTailRecurse(falseType, mapper)) { + continue; + } + } + result = instantiateType(falseType, mapper); + break; + } + // Return trueType for a definitely true extends check. We check instantiations of the two + // types with type parameters mapped to their restrictive form, i.e. a form of the type parameter + // that has no constraint. This ensures that, for example, the type + // type Foo = T extends { x: string } ? string : number + // doesn't immediately resolve to 'string' instead of being deferred. + if (inferredExtendsType.flags & TypeFlags.AnyOrUnknown || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(inferredExtendsType))) { + const trueType = getTypeFromTypeNode(root.node.trueType); + const trueMapper = combinedMapper || mapper; + if (canTailRecurse(trueType, trueMapper)) { + continue; + } + result = instantiateType(trueType, trueMapper); + break; + } + } + // Return a deferred type for a check that is neither definitely true nor definitely false + result = createType(TypeFlags.Conditional) as ConditionalType; + result.root = root; + result.checkType = instantiateType(root.checkType, mapper); + result.extendsType = instantiateType(root.extendsType, mapper); + result.mapper = mapper; + result.combinedMapper = combinedMapper; + result.aliasSymbol = aliasSymbol || root.aliasSymbol; + result.aliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(root.aliasTypeArguments, mapper!); // TODO: GH#18217 + break; + } + return extraTypes ? getUnionType(append(extraTypes, result)) : result; + // We tail-recurse for generic conditional types that (a) have not already been evaluated and cached, and + // (b) are non distributive, have a check type that is unaffected by instantiation, or have a non-union check + // type. Note that recursion is possible only through aliased conditional types, so we only increment the tail + // recursion counter for those. + function canTailRecurse(newType: Type, newMapper: TypeMapper | undefined) { + if (newType.flags & TypeFlags.Conditional && newMapper) { + const newRoot = (newType as ConditionalType).root; + if (newRoot.outerTypeParameters) { + const typeParamMapper = combineTypeMappers((newType as ConditionalType).mapper, newMapper); + const typeArguments = map(newRoot.outerTypeParameters, t => getMappedType(t, typeParamMapper)); + const newRootMapper = createTypeMapper(newRoot.outerTypeParameters, typeArguments); + const newCheckType = newRoot.isDistributive ? getMappedType(newRoot.checkType, newRootMapper) : undefined; + if (!newCheckType || newCheckType === newRoot.checkType || !(newCheckType.flags & (TypeFlags.Union | TypeFlags.Never))) { + root = newRoot; + mapper = newRootMapper; + aliasSymbol = undefined; + aliasTypeArguments = undefined; + if (newRoot.aliasSymbol) { + tailCount++; + } + return true; + } + } + } + return false; + } + } + + function getTrueTypeFromConditionalType(type: ConditionalType) { + return type.resolvedTrueType || (type.resolvedTrueType = instantiateType(getTypeFromTypeNode(type.root.node.trueType), type.mapper)); + } + + function getFalseTypeFromConditionalType(type: ConditionalType) { + return type.resolvedFalseType || (type.resolvedFalseType = instantiateType(getTypeFromTypeNode(type.root.node.falseType), type.mapper)); + } + + function getInferredTrueTypeFromConditionalType(type: ConditionalType) { + return type.resolvedInferredTrueType || (type.resolvedInferredTrueType = type.combinedMapper ? instantiateType(getTypeFromTypeNode(type.root.node.trueType), type.combinedMapper) : getTrueTypeFromConditionalType(type)); + } + + function getInferTypeParameters(node: ConditionalTypeNode): TypeParameter[] | undefined { + let result: TypeParameter[] | undefined; + if (node.locals) { + node.locals.forEach(symbol => { + if (symbol.flags & SymbolFlags.TypeParameter) { + result = append(result, getDeclaredTypeOfSymbol(symbol)); + } + }); + } + return result; + } + + function isDistributionDependent(root: ConditionalRoot) { + return root.isDistributive && ( + isTypeParameterPossiblyReferenced(root.checkType as TypeParameter, root.node.trueType) || + isTypeParameterPossiblyReferenced(root.checkType as TypeParameter, root.node.falseType) + ); + } + + function getTypeFromConditionalTypeNode(node: ConditionalTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const checkType = getTypeFromTypeNode(node.checkType); + const aliasSymbol = getAliasSymbolForTypeNode(node); + const aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); + const allOuterTypeParameters = getOuterTypeParameters(node, /*includeThisTypes*/ true); + const outerTypeParameters = aliasTypeArguments ? allOuterTypeParameters : filter(allOuterTypeParameters, tp => isTypeParameterPossiblyReferenced(tp, node)); + const root: ConditionalRoot = { + node, + checkType, + extendsType: getTypeFromTypeNode(node.extendsType), + isDistributive: !!(checkType.flags & TypeFlags.TypeParameter), + inferTypeParameters: getInferTypeParameters(node), + outerTypeParameters, + instantiations: undefined, + aliasSymbol, + aliasTypeArguments, + }; + links.resolvedType = getConditionalType(root, /*mapper*/ undefined, /*forConstraint*/ false); + if (outerTypeParameters) { + root.instantiations = new Map(); + root.instantiations.set(getTypeListId(outerTypeParameters), links.resolvedType); + } + } + return links.resolvedType; + } + + function getTypeFromInferTypeNode(node: InferTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node.typeParameter)); + } + return links.resolvedType; + } + + function getIdentifierChain(node: EntityName): Identifier[] { + if (isIdentifier(node)) { + return [node]; + } + else { + return append(getIdentifierChain(node.left), node.right); + } + } + + function getTypeFromImportTypeNode(node: ImportTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + if (!isLiteralImportTypeNode(node)) { + error(node.argument, Diagnostics.String_literal_expected); + links.resolvedSymbol = unknownSymbol; + return links.resolvedType = errorType; + } + const targetMeaning = node.isTypeOf ? SymbolFlags.Value : node.flags & NodeFlags.JSDoc ? SymbolFlags.Value | SymbolFlags.Type : SymbolFlags.Type; + // TODO: Future work: support unions/generics/whatever via a deferred import-type + const innerModuleSymbol = resolveExternalModuleName(node, node.argument.literal); + if (!innerModuleSymbol) { + links.resolvedSymbol = unknownSymbol; + return links.resolvedType = errorType; + } + const isExportEquals = !!innerModuleSymbol.exports?.get(InternalSymbolName.ExportEquals); + const moduleSymbol = resolveExternalModuleSymbol(innerModuleSymbol, /*dontResolveAlias*/ false); + if (!nodeIsMissing(node.qualifier)) { + const nameStack: Identifier[] = getIdentifierChain(node.qualifier!); + let currentNamespace = moduleSymbol; + let current: Identifier | undefined; + while (current = nameStack.shift()) { + const meaning = nameStack.length ? SymbolFlags.Namespace : targetMeaning; + // typeof a.b.c is normally resolved using `checkExpression` which in turn defers to `checkQualifiedName` + // That, in turn, ultimately uses `getPropertyOfType` on the type of the symbol, which differs slightly from + // the `exports` lookup process that only looks up namespace members which is used for most type references + const mergedResolvedSymbol = getMergedSymbol(resolveSymbol(currentNamespace)); + const symbolFromVariable = node.isTypeOf || isInJSFile(node) && isExportEquals + ? getPropertyOfType(getTypeOfSymbol(mergedResolvedSymbol), current.escapedText, /*skipObjectFunctionPropertyAugment*/ false, /*includeTypeOnlyMembers*/ true) + : undefined; + const symbolFromModule = node.isTypeOf ? undefined : getSymbol(getExportsOfSymbol(mergedResolvedSymbol), current.escapedText, meaning); + const next = symbolFromModule ?? symbolFromVariable; + if (!next) { + error(current, Diagnostics.Namespace_0_has_no_exported_member_1, getFullyQualifiedName(currentNamespace), declarationNameToString(current)); + return links.resolvedType = errorType; + } + getNodeLinks(current).resolvedSymbol = next; + getNodeLinks(current.parent).resolvedSymbol = next; + currentNamespace = next; + } + links.resolvedType = resolveImportSymbolType(node, links, currentNamespace, targetMeaning); + } + else { + if (moduleSymbol.flags & targetMeaning) { + links.resolvedType = resolveImportSymbolType(node, links, moduleSymbol, targetMeaning); + } + else { + const errorMessage = targetMeaning === SymbolFlags.Value + ? Diagnostics.Module_0_does_not_refer_to_a_value_but_is_used_as_a_value_here + : Diagnostics.Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here_Did_you_mean_typeof_import_0; + + error(node, errorMessage, node.argument.literal.text); + + links.resolvedSymbol = unknownSymbol; + links.resolvedType = errorType; + } + } + } + return links.resolvedType; + } + + function resolveImportSymbolType(node: ImportTypeNode, links: NodeLinks, symbol: Symbol, meaning: SymbolFlags) { + const resolvedSymbol = resolveSymbol(symbol); + links.resolvedSymbol = resolvedSymbol; + if (meaning === SymbolFlags.Value) { + return getInstantiationExpressionType(getTypeOfSymbol(symbol), node); // intentionally doesn't use resolved symbol so type is cached as expected on the alias + } + else { + return getTypeReferenceType(node, resolvedSymbol); // getTypeReferenceType doesn't handle aliases - it must get the resolved symbol + } + } + + function getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node: TypeLiteralNode | FunctionOrConstructorTypeNode | JSDocTypeLiteral | JSDocFunctionType | JSDocSignature): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + // Deferred resolution of members is handled by resolveObjectTypeMembers + const aliasSymbol = getAliasSymbolForTypeNode(node); + if (getMembersOfSymbol(node.symbol).size === 0 && !aliasSymbol) { + links.resolvedType = emptyTypeLiteralType; + } + else { + let type = createObjectType(ObjectFlags.Anonymous, node.symbol); + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); + if (isJSDocTypeLiteral(node) && node.isArrayType) { + type = createArrayType(type); + } + links.resolvedType = type; + } + } + return links.resolvedType; + } + + function getAliasSymbolForTypeNode(node: Node) { + let host = node.parent; + while (isParenthesizedTypeNode(host) || isJSDocTypeExpression(host) || isTypeOperatorNode(host) && host.operator === SyntaxKind.ReadonlyKeyword) { + host = host.parent; + } + return isTypeAlias(host) ? getSymbolOfDeclaration(host) : undefined; + } + + function getTypeArgumentsForAliasSymbol(symbol: Symbol | undefined) { + return symbol ? getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol) : undefined; + } + + function isNonGenericObjectType(type: Type) { + return !!(type.flags & TypeFlags.Object) && !isGenericMappedType(type); + } + + function isEmptyObjectTypeOrSpreadsIntoEmptyObject(type: Type) { + return isEmptyObjectType(type) || !!(type.flags & (TypeFlags.Null | TypeFlags.Undefined | TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)); + } + + function tryMergeUnionOfObjectTypeAndEmptyObject(type: Type, readonly: boolean): Type { + if (!(type.flags & TypeFlags.Union)) { + return type; + } + if (every((type as UnionType).types, isEmptyObjectTypeOrSpreadsIntoEmptyObject)) { + return find((type as UnionType).types, isEmptyObjectType) || emptyObjectType; + } + const firstType = find((type as UnionType).types, t => !isEmptyObjectTypeOrSpreadsIntoEmptyObject(t)); + if (!firstType) { + return type; + } + const secondType = find((type as UnionType).types, t => t !== firstType && !isEmptyObjectTypeOrSpreadsIntoEmptyObject(t)); + if (secondType) { + return type; + } + return getAnonymousPartialType(firstType); + + function getAnonymousPartialType(type: Type) { + // gets the type as if it had been spread, but where everything in the spread is made optional + const members = createSymbolTable(); + for (const prop of getPropertiesOfType(type)) { + if (getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) { + // do nothing, skip privates + } + else if (isSpreadableProperty(prop)) { + const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); + const flags = SymbolFlags.Property | SymbolFlags.Optional; + const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0)); + result.links.type = isSetonlyAccessor ? undefinedType : addOptionality(getTypeOfSymbol(prop), /*isProperty*/ true); + result.declarations = prop.declarations; + result.links.nameType = getSymbolLinks(prop).nameType; + result.links.syntheticOrigin = prop; + members.set(prop.escapedName, result); + } + } + const spread = createAnonymousType(type.symbol, members, emptyArray, emptyArray, getIndexInfosOfType(type)); + spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + return spread; + } + } + + /** + * Since the source of spread types are object literals, which are not binary, + * this function should be called in a left folding style, with left = previous result of getSpreadType + * and right = the new element to be spread. + */ + function getSpreadType(left: Type, right: Type, symbol: Symbol | undefined, objectFlags: ObjectFlags, readonly: boolean): Type { + if (left.flags & TypeFlags.Any || right.flags & TypeFlags.Any) { + return anyType; + } + if (left.flags & TypeFlags.Unknown || right.flags & TypeFlags.Unknown) { + return unknownType; + } + if (left.flags & TypeFlags.Never) { + return right; + } + if (right.flags & TypeFlags.Never) { + return left; + } + left = tryMergeUnionOfObjectTypeAndEmptyObject(left, readonly); + if (left.flags & TypeFlags.Union) { + return checkCrossProductUnion([left, right]) + ? mapType(left, t => getSpreadType(t, right, symbol, objectFlags, readonly)) + : errorType; + } + right = tryMergeUnionOfObjectTypeAndEmptyObject(right, readonly); + if (right.flags & TypeFlags.Union) { + return checkCrossProductUnion([left, right]) + ? mapType(right, t => getSpreadType(left, t, symbol, objectFlags, readonly)) + : errorType; + } + if (right.flags & (TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)) { + return left; + } + + if (isGenericObjectType(left) || isGenericObjectType(right)) { + if (isEmptyObjectType(left)) { + return right; + } + // When the left type is an intersection, we may need to merge the last constituent of the + // intersection with the right type. For example when the left type is 'T & { a: string }' + // and the right type is '{ b: string }' we produce 'T & { a: string, b: string }'. + if (left.flags & TypeFlags.Intersection) { + const types = (left as IntersectionType).types; + const lastLeft = types[types.length - 1]; + if (isNonGenericObjectType(lastLeft) && isNonGenericObjectType(right)) { + return getIntersectionType(concatenate(types.slice(0, types.length - 1), [getSpreadType(lastLeft, right, symbol, objectFlags, readonly)])); + } + } + return getIntersectionType([left, right]); + } + + const members = createSymbolTable(); + const skippedPrivateMembers = new Set<__String>(); + const indexInfos = left === emptyObjectType ? getIndexInfosOfType(right) : getUnionIndexInfos([left, right]); + + for (const rightProp of getPropertiesOfType(right)) { + if (getDeclarationModifierFlagsFromSymbol(rightProp) & (ModifierFlags.Private | ModifierFlags.Protected)) { + skippedPrivateMembers.add(rightProp.escapedName); + } + else if (isSpreadableProperty(rightProp)) { + members.set(rightProp.escapedName, getSpreadSymbol(rightProp, readonly)); + } + } + + for (const leftProp of getPropertiesOfType(left)) { + if (skippedPrivateMembers.has(leftProp.escapedName) || !isSpreadableProperty(leftProp)) { + continue; + } + if (members.has(leftProp.escapedName)) { + const rightProp = members.get(leftProp.escapedName)!; + const rightType = getTypeOfSymbol(rightProp); + if (rightProp.flags & SymbolFlags.Optional) { + const declarations = concatenate(leftProp.declarations, rightProp.declarations); + const flags = SymbolFlags.Property | (leftProp.flags & SymbolFlags.Optional); + const result = createSymbol(flags, leftProp.escapedName); + // Optimization: avoid calculating the union type if spreading into the exact same type. + // This is common, e.g. spreading one options bag into another where the bags have the + // same type, or have properties which overlap. If the unions are large, it may turn out + // to be expensive to perform subtype reduction. + const leftType = getTypeOfSymbol(leftProp); + const leftTypeWithoutUndefined = removeMissingOrUndefinedType(leftType); + const rightTypeWithoutUndefined = removeMissingOrUndefinedType(rightType); + result.links.type = leftTypeWithoutUndefined === rightTypeWithoutUndefined ? leftType : getUnionType([leftType, rightTypeWithoutUndefined], UnionReduction.Subtype); + result.links.leftSpread = leftProp; + result.links.rightSpread = rightProp; + result.declarations = declarations; + result.links.nameType = getSymbolLinks(leftProp).nameType; + members.set(leftProp.escapedName, result); + } + } + else { + members.set(leftProp.escapedName, getSpreadSymbol(leftProp, readonly)); + } + } + + const spread = createAnonymousType(symbol, members, emptyArray, emptyArray, sameMap(indexInfos, info => getIndexInfoWithReadonly(info, readonly))); + spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral | ObjectFlags.ContainsSpread | objectFlags; + return spread; + } + + /** We approximate own properties as non-methods plus methods that are inside the object literal */ + function isSpreadableProperty(prop: Symbol): boolean { + return !some(prop.declarations, isPrivateIdentifierClassElementDeclaration) && + (!(prop.flags & (SymbolFlags.Method | SymbolFlags.GetAccessor | SymbolFlags.SetAccessor)) || + !prop.declarations?.some(decl => isClassLike(decl.parent))); + } + + function getSpreadSymbol(prop: Symbol, readonly: boolean) { + const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); + if (!isSetonlyAccessor && readonly === isReadonlySymbol(prop)) { + return prop; + } + const flags = SymbolFlags.Property | (prop.flags & SymbolFlags.Optional); + const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0)); + result.links.type = isSetonlyAccessor ? undefinedType : getTypeOfSymbol(prop); + result.declarations = prop.declarations; + result.links.nameType = getSymbolLinks(prop).nameType; + result.links.syntheticOrigin = prop; + return result; + } + + function getIndexInfoWithReadonly(info: IndexInfo, readonly: boolean) { + return info.isReadonly !== readonly ? createIndexInfo(info.keyType, info.type, readonly, info.declaration) : info; + } + + function createLiteralType(flags: TypeFlags, value: string | number | PseudoBigInt, symbol?: Symbol, regularType?: LiteralType) { + const type = createTypeWithSymbol(flags, symbol!) as LiteralType; + type.value = value; + type.regularType = regularType || type; + return type; + } + + function getFreshTypeOfLiteralType(type: Type): Type { + if (type.flags & TypeFlags.Freshable) { + if (!(type as FreshableType).freshType) { + const freshType = createLiteralType(type.flags, (type as LiteralType).value, (type as LiteralType).symbol, type as LiteralType); + freshType.freshType = freshType; + (type as FreshableType).freshType = freshType; + } + return (type as FreshableType).freshType; + } + return type; + } + + function getRegularTypeOfLiteralType(type: Type): Type { + return type.flags & TypeFlags.Freshable ? (type as FreshableType).regularType : + type.flags & TypeFlags.Union ? ((type as UnionType).regularType || ((type as UnionType).regularType = mapType(type, getRegularTypeOfLiteralType) as UnionType)) : + type; + } + + function isFreshLiteralType(type: Type) { + return !!(type.flags & TypeFlags.Freshable) && (type as LiteralType).freshType === type; + } + + function getStringLiteralType(value: string): StringLiteralType { + let type; + return stringLiteralTypes.get(value) || + (stringLiteralTypes.set(value, type = createLiteralType(TypeFlags.StringLiteral, value) as StringLiteralType), type); + } + + function getNumberLiteralType(value: number): NumberLiteralType { + let type; + return numberLiteralTypes.get(value) || + (numberLiteralTypes.set(value, type = createLiteralType(TypeFlags.NumberLiteral, value) as NumberLiteralType), type); + } + + function getBigIntLiteralType(value: PseudoBigInt): BigIntLiteralType { + let type; + const key = pseudoBigIntToString(value); + return bigIntLiteralTypes.get(key) || + (bigIntLiteralTypes.set(key, type = createLiteralType(TypeFlags.BigIntLiteral, value) as BigIntLiteralType), type); + } + + function getEnumLiteralType(value: string | number, enumId: number, symbol: Symbol): LiteralType { + let type; + const key = `${enumId}${typeof value === "string" ? "@" : "#"}${value}`; + const flags = TypeFlags.EnumLiteral | (typeof value === "string" ? TypeFlags.StringLiteral : TypeFlags.NumberLiteral); + return enumLiteralTypes.get(key) || + (enumLiteralTypes.set(key, type = createLiteralType(flags, value, symbol)), type); + } + + function getTypeFromLiteralTypeNode(node: LiteralTypeNode): Type { + if (node.literal.kind === SyntaxKind.NullKeyword) { + return nullType; + } + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getRegularTypeOfLiteralType(checkExpression(node.literal)); + } + return links.resolvedType; + } + + function createUniqueESSymbolType(symbol: Symbol) { + const type = createTypeWithSymbol(TypeFlags.UniqueESSymbol, symbol) as UniqueESSymbolType; + type.escapedName = `__@${type.symbol.escapedName}@${getSymbolId(type.symbol)}` as __String; + return type; + } + + function getESSymbolLikeTypeForNode(node: Node) { + if (isInJSFile(node) && isJSDocTypeExpression(node)) { + const host = getJSDocHost(node); + if (host) { + node = getSingleVariableOfVariableStatement(host) || host; + } + } + if (isValidESSymbolDeclaration(node)) { + const symbol = isCommonJsExportPropertyAssignment(node) ? getSymbolOfNode((node as BinaryExpression).left) : getSymbolOfNode(node); + if (symbol) { + const links = getSymbolLinks(symbol); + return links.uniqueESSymbolType || (links.uniqueESSymbolType = createUniqueESSymbolType(symbol)); + } + } + return esSymbolType; + } + + function getThisType(node: Node): Type { + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + const parent = container && container.parent; + if (parent && (isClassLike(parent) || parent.kind === SyntaxKind.InterfaceDeclaration)) { + if ( + !isStatic(container) && + (!isConstructorDeclaration(container) || isNodeDescendantOf(node, container.body)) + ) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(parent as ClassLikeDeclaration | InterfaceDeclaration)).thisType!; + } + } + + // inside x.prototype = { ... } + if (parent && isObjectLiteralExpression(parent) && isBinaryExpression(parent.parent) && getAssignmentDeclarationKind(parent.parent) === AssignmentDeclarationKind.Prototype) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfNode(parent.parent.left)!.parent!).thisType!; + } + // /** @return {this} */ + // x.prototype.m = function() { ... } + const host = node.flags & NodeFlags.JSDoc ? getHostSignatureFromJSDoc(node) : undefined; + if (host && isFunctionExpression(host) && isBinaryExpression(host.parent) && getAssignmentDeclarationKind(host.parent) === AssignmentDeclarationKind.PrototypeProperty) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfNode(host.parent.left)!.parent!).thisType!; + } + // inside constructor function C() { ... } + if (isJSConstructor(container) && isNodeDescendantOf(node, container.body)) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(container)).thisType!; + } + error(node, Diagnostics.A_this_type_is_available_only_in_a_non_static_member_of_a_class_or_interface); + return errorType; + } + + function getTypeFromThisTypeNode(node: ThisExpression | ThisTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getThisType(node); + } + return links.resolvedType; + } + + function getTypeFromRestTypeNode(node: RestTypeNode | NamedTupleMember) { + return getTypeFromTypeNode(getArrayElementTypeNode(node.type) || node.type); + } + + function getArrayElementTypeNode(node: TypeNode): TypeNode | undefined { + switch (node.kind) { + case SyntaxKind.ParenthesizedType: + return getArrayElementTypeNode((node as ParenthesizedTypeNode).type); + case SyntaxKind.TupleType: + if ((node as TupleTypeNode).elements.length === 1) { + node = (node as TupleTypeNode).elements[0]; + if (node.kind === SyntaxKind.RestType || node.kind === SyntaxKind.NamedTupleMember && (node as NamedTupleMember).dotDotDotToken) { + return getArrayElementTypeNode((node as RestTypeNode | NamedTupleMember).type); + } + } + break; + case SyntaxKind.ArrayType: + return (node as ArrayTypeNode).elementType; + } + return undefined; + } + + function getTypeFromNamedTupleTypeNode(node: NamedTupleMember): Type { + const links = getNodeLinks(node); + return links.resolvedType || (links.resolvedType = node.dotDotDotToken ? getTypeFromRestTypeNode(node) : + addOptionality(getTypeFromTypeNode(node.type), /*isProperty*/ true, !!node.questionToken)); + } + + function getTypeFromTypeNode(node: TypeNode): Type { + return getConditionalFlowTypeOfType(getTypeFromTypeNodeWorker(node), node); + } + + function getTypeFromTypeNodeWorker(node: TypeNode): Type { + switch (node.kind) { + case SyntaxKind.AnyKeyword: + case SyntaxKind.JSDocAllType: + case SyntaxKind.JSDocUnknownType: + return anyType; + case SyntaxKind.UnknownKeyword: + return unknownType; + case SyntaxKind.StringKeyword: + return stringType; + case SyntaxKind.NumberKeyword: + return numberType; + case SyntaxKind.BigIntKeyword: + return bigintType; + case SyntaxKind.BooleanKeyword: + return booleanType; + case SyntaxKind.SymbolKeyword: + return esSymbolType; + case SyntaxKind.VoidKeyword: + return voidType; + case SyntaxKind.UndefinedKeyword: + return undefinedType; + case SyntaxKind.NullKeyword as TypeNodeSyntaxKind: + // TODO(rbuckton): `NullKeyword` is no longer a `TypeNode`, but we defensively allow it here because of incorrect casts in the Language Service. + return nullType; + case SyntaxKind.NeverKeyword: + return neverType; + case SyntaxKind.ObjectKeyword: + return node.flags & NodeFlags.JavaScriptFile && !noImplicitAny ? anyType : nonPrimitiveType; + case SyntaxKind.IntrinsicKeyword: + return intrinsicMarkerType; + case SyntaxKind.ThisType: + case SyntaxKind.ThisKeyword as TypeNodeSyntaxKind: + // TODO(rbuckton): `ThisKeyword` is no longer a `TypeNode`, but we defensively allow it here because of incorrect casts in the Language Service and because of `isPartOfTypeNode`. + return getTypeFromThisTypeNode(node as ThisExpression | ThisTypeNode); + case SyntaxKind.LiteralType: + return getTypeFromLiteralTypeNode(node as LiteralTypeNode); + case SyntaxKind.TypeReference: + return getTypeFromTypeReference(node as TypeReferenceNode); + case SyntaxKind.TypePredicate: + return (node as TypePredicateNode).assertsModifier ? voidType : booleanType; + case SyntaxKind.ExpressionWithTypeArguments: + return getTypeFromTypeReference(node as ExpressionWithTypeArguments); + case SyntaxKind.TypeQuery: + return getTypeFromTypeQueryNode(node as TypeQueryNode); + case SyntaxKind.ArrayType: + case SyntaxKind.TupleType: + return getTypeFromArrayOrTupleTypeNode(node as ArrayTypeNode | TupleTypeNode); + case SyntaxKind.OptionalType: + return getTypeFromOptionalTypeNode(node as OptionalTypeNode); + case SyntaxKind.UnionType: + return getTypeFromUnionTypeNode(node as UnionTypeNode); + case SyntaxKind.IntersectionType: + return getTypeFromIntersectionTypeNode(node as IntersectionTypeNode); + case SyntaxKind.JSDocNullableType: + return getTypeFromJSDocNullableTypeNode(node as JSDocNullableType); + case SyntaxKind.JSDocOptionalType: + return addOptionality(getTypeFromTypeNode((node as JSDocOptionalType).type)); + case SyntaxKind.NamedTupleMember: + return getTypeFromNamedTupleTypeNode(node as NamedTupleMember); + case SyntaxKind.ParenthesizedType: + case SyntaxKind.JSDocNonNullableType: + case SyntaxKind.JSDocTypeExpression: + return getTypeFromTypeNode((node as ParenthesizedTypeNode | JSDocTypeReferencingNode | JSDocTypeExpression | NamedTupleMember).type); + case SyntaxKind.RestType: + return getTypeFromRestTypeNode(node as RestTypeNode); + case SyntaxKind.JSDocVariadicType: + return getTypeFromJSDocVariadicType(node as JSDocVariadicType); + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.TypeLiteral: + case SyntaxKind.JSDocTypeLiteral: + case SyntaxKind.JSDocFunctionType: + case SyntaxKind.JSDocSignature: + return getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node as TypeLiteralNode | FunctionOrConstructorTypeNode | JSDocTypeLiteral | JSDocFunctionType | JSDocSignature); + case SyntaxKind.TypeOperator: + return getTypeFromTypeOperatorNode(node as TypeOperatorNode); + case SyntaxKind.IndexedAccessType: + return getTypeFromIndexedAccessTypeNode(node as IndexedAccessTypeNode); + case SyntaxKind.MappedType: + return getTypeFromMappedTypeNode(node as MappedTypeNode); + case SyntaxKind.ConditionalType: + return getTypeFromConditionalTypeNode(node as ConditionalTypeNode); + case SyntaxKind.InferType: + return getTypeFromInferTypeNode(node as InferTypeNode); + case SyntaxKind.TemplateLiteralType: + return getTypeFromTemplateTypeNode(node as TemplateLiteralTypeNode); + case SyntaxKind.ImportType: + return getTypeFromImportTypeNode(node as ImportTypeNode); + // This function assumes that an identifier, qualified name, or property access expression is a type expression + // Callers should first ensure this by calling `isPartOfTypeNode` + // TODO(rbuckton): These aren't valid TypeNodes, but we treat them as such because of `isPartOfTypeNode`, which returns `true` for things that aren't `TypeNode`s. + case SyntaxKind.Identifier as TypeNodeSyntaxKind: + case SyntaxKind.QualifiedName as TypeNodeSyntaxKind: + case SyntaxKind.PropertyAccessExpression as TypeNodeSyntaxKind: + const symbol = getSymbolAtLocation(node); + return symbol ? getDeclaredTypeOfSymbol(symbol) : errorType; + default: + return errorType; + } + } + + function instantiateList(items: readonly T[], mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[]; + function instantiateList(items: readonly T[] | undefined, mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[] | undefined; + function instantiateList(items: readonly T[] | undefined, mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[] | undefined { + if (items && items.length) { + for (let i = 0; i < items.length; i++) { + const item = items[i]; + const mapped = instantiator(item, mapper); + if (item !== mapped) { + const result = i === 0 ? [] : items.slice(0, i); + result.push(mapped); + for (i++; i < items.length; i++) { + result.push(instantiator(items[i], mapper)); + } + return result; + } + } + } + return items; + } + + function instantiateTypes(types: readonly Type[], mapper: TypeMapper): readonly Type[]; + function instantiateTypes(types: readonly Type[] | undefined, mapper: TypeMapper): readonly Type[] | undefined; + function instantiateTypes(types: readonly Type[] | undefined, mapper: TypeMapper): readonly Type[] | undefined { + return instantiateList(types, mapper, instantiateType); + } + + function instantiateSignatures(signatures: readonly Signature[], mapper: TypeMapper): readonly Signature[] { + return instantiateList(signatures, mapper, instantiateSignature); + } + + function instantiateIndexInfos(indexInfos: readonly IndexInfo[], mapper: TypeMapper): readonly IndexInfo[] { + return instantiateList(indexInfos, mapper, instantiateIndexInfo); + } + + function createTypeMapper(sources: readonly TypeParameter[], targets: readonly Type[] | undefined): TypeMapper { + return sources.length === 1 ? makeUnaryTypeMapper(sources[0], targets ? targets[0] : anyType) : makeArrayTypeMapper(sources, targets); + } + + function getMappedType(type: Type, mapper: TypeMapper): Type { + switch (mapper.kind) { + case TypeMapKind.Simple: + return type === mapper.source ? mapper.target : type; + case TypeMapKind.Array: { + const sources = mapper.sources; + const targets = mapper.targets; + for (let i = 0; i < sources.length; i++) { + if (type === sources[i]) { + return targets ? targets[i] : anyType; + } + } + return type; + } + case TypeMapKind.Deferred: { + const sources = mapper.sources; + const targets = mapper.targets; + for (let i = 0; i < sources.length; i++) { + if (type === sources[i]) { + return targets[i](); + } + } + return type; + } + case TypeMapKind.Function: + return mapper.func(type); + case TypeMapKind.Composite: + case TypeMapKind.Merged: + const t1 = getMappedType(type, mapper.mapper1); + return t1 !== type && mapper.kind === TypeMapKind.Composite ? instantiateType(t1, mapper.mapper2) : getMappedType(t1, mapper.mapper2); + } + } + + function makeUnaryTypeMapper(source: Type, target: Type): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Simple, source, target }); + } + + function makeArrayTypeMapper(sources: readonly TypeParameter[], targets: readonly Type[] | undefined): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Array, sources, targets }); + } + + function makeFunctionTypeMapper(func: (t: Type) => Type, debugInfo: () => string): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Function, func, debugInfo: Debug.isDebugging ? debugInfo : undefined }); + } + + function makeDeferredTypeMapper(sources: readonly TypeParameter[], targets: (() => Type)[]) { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Deferred, sources, targets }); + } + + function makeCompositeTypeMapper(kind: TypeMapKind.Composite | TypeMapKind.Merged, mapper1: TypeMapper, mapper2: TypeMapper): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind, mapper1, mapper2 }); + } + + function createTypeEraser(sources: readonly TypeParameter[]): TypeMapper { + return createTypeMapper(sources, /*targets*/ undefined); + } + + /** + * Maps forward-references to later types parameters to the empty object type. + * This is used during inference when instantiating type parameter defaults. + */ + function createBackreferenceMapper(context: InferenceContext, index: number): TypeMapper { + const forwardInferences = context.inferences.slice(index); + return createTypeMapper(map(forwardInferences, i => i.typeParameter), map(forwardInferences, () => unknownType)); + } + + function combineTypeMappers(mapper1: TypeMapper | undefined, mapper2: TypeMapper): TypeMapper { + return mapper1 ? makeCompositeTypeMapper(TypeMapKind.Composite, mapper1, mapper2) : mapper2; + } + + function mergeTypeMappers(mapper1: TypeMapper | undefined, mapper2: TypeMapper): TypeMapper { + return mapper1 ? makeCompositeTypeMapper(TypeMapKind.Merged, mapper1, mapper2) : mapper2; + } + + function prependTypeMapping(source: Type, target: Type, mapper: TypeMapper | undefined) { + return !mapper ? makeUnaryTypeMapper(source, target) : makeCompositeTypeMapper(TypeMapKind.Merged, makeUnaryTypeMapper(source, target), mapper); + } + + function appendTypeMapping(mapper: TypeMapper | undefined, source: Type, target: Type) { + return !mapper ? makeUnaryTypeMapper(source, target) : makeCompositeTypeMapper(TypeMapKind.Merged, mapper, makeUnaryTypeMapper(source, target)); + } + + function getRestrictiveTypeParameter(tp: TypeParameter) { + return !tp.constraint && !getConstraintDeclaration(tp) || tp.constraint === noConstraintType ? tp : tp.restrictiveInstantiation || ( + tp.restrictiveInstantiation = createTypeParameter(tp.symbol), (tp.restrictiveInstantiation as TypeParameter).constraint = noConstraintType, tp.restrictiveInstantiation + ); + } + + function cloneTypeParameter(typeParameter: TypeParameter): TypeParameter { + const result = createTypeParameter(typeParameter.symbol); + result.target = typeParameter; + return result; + } + + function instantiateTypePredicate(predicate: TypePredicate, mapper: TypeMapper): TypePredicate { + return createTypePredicate(predicate.kind, predicate.parameterName, predicate.parameterIndex, instantiateType(predicate.type, mapper)); + } + + function instantiateSignature(signature: Signature, mapper: TypeMapper, eraseTypeParameters?: boolean): Signature { + let freshTypeParameters: TypeParameter[] | undefined; + if (signature.typeParameters && !eraseTypeParameters) { + // First create a fresh set of type parameters, then include a mapping from the old to the + // new type parameters in the mapper function. Finally store this mapper in the new type + // parameters such that we can use it when instantiating constraints. + freshTypeParameters = map(signature.typeParameters, cloneTypeParameter); + mapper = combineTypeMappers(createTypeMapper(signature.typeParameters, freshTypeParameters), mapper); + for (const tp of freshTypeParameters) { + tp.mapper = mapper; + } + } + // Don't compute resolvedReturnType and resolvedTypePredicate now, + // because using `mapper` now could trigger inferences to become fixed. (See `createInferenceContext`.) + // See GH#17600. + const result = createSignature(signature.declaration, freshTypeParameters, signature.thisParameter && instantiateSymbol(signature.thisParameter, mapper), instantiateList(signature.parameters, mapper, instantiateSymbol), /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, signature.minArgumentCount, signature.flags & SignatureFlags.PropagatingFlags); + result.target = signature; + result.mapper = mapper; + return result; + } + + function instantiateSymbol(symbol: Symbol, mapper: TypeMapper): Symbol { + const links = getSymbolLinks(symbol); + // If the type of the symbol is already resolved, and if that type could not possibly + // be affected by instantiation, simply return the symbol itself. + if (links.type && !couldContainTypeVariables(links.type)) { + if (!(symbol.flags & SymbolFlags.SetAccessor)) { + return symbol; + } + // If we're a setter, check writeType. + if (links.writeType && !couldContainTypeVariables(links.writeType)) { + return symbol; + } + } + if (getCheckFlags(symbol) & CheckFlags.Instantiated) { + // If symbol being instantiated is itself a instantiation, fetch the original target and combine the + // type mappers. This ensures that original type identities are properly preserved and that aliases + // always reference a non-aliases. + symbol = links.target!; + mapper = combineTypeMappers(links.mapper, mapper); + } + // Keep the flags from the symbol we're instantiating. Mark that is instantiated, and + // also transient so that we can just store data on it directly. + const result = createSymbol(symbol.flags, symbol.escapedName, CheckFlags.Instantiated | getCheckFlags(symbol) & (CheckFlags.Readonly | CheckFlags.Late | CheckFlags.OptionalParameter | CheckFlags.RestParameter)); + result.declarations = symbol.declarations; + result.parent = symbol.parent; + result.links.target = symbol; + result.links.mapper = mapper; + if (symbol.valueDeclaration) { + result.valueDeclaration = symbol.valueDeclaration; + } + if (links.nameType) { + result.links.nameType = links.nameType; + } + return result; + } + + function getObjectTypeInstantiation(type: AnonymousType | DeferredTypeReference, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]) { + const declaration = type.objectFlags & ObjectFlags.Reference ? (type as TypeReference).node! : + type.objectFlags & ObjectFlags.InstantiationExpressionType ? (type as InstantiationExpressionType).node : + type.symbol.declarations![0]; + const links = getNodeLinks(declaration); + const target = type.objectFlags & ObjectFlags.Reference ? links.resolvedType! as DeferredTypeReference : + type.objectFlags & ObjectFlags.Instantiated ? type.target! : type; + let typeParameters = type.objectFlags & ObjectFlags.SingleSignatureType ? (type as SingleSignatureType).outerTypeParameters : links.outerTypeParameters; + if (!typeParameters) { + // The first time an anonymous type is instantiated we compute and store a list of the type + // parameters that are in scope (and therefore potentially referenced). For type literals that + // aren't the right hand side of a generic type alias declaration we optimize by reducing the + // set of type parameters to those that are possibly referenced in the literal. + let outerTypeParameters = getOuterTypeParameters(declaration, /*includeThisTypes*/ true); + if (isJSConstructor(declaration)) { + const templateTagParameters = getTypeParametersFromDeclaration(declaration as DeclarationWithTypeParameters); + outerTypeParameters = addRange(outerTypeParameters, templateTagParameters); + } + typeParameters = outerTypeParameters || emptyArray; + const allDeclarations = type.objectFlags & (ObjectFlags.Reference | ObjectFlags.InstantiationExpressionType) ? [declaration] : type.symbol.declarations!; + typeParameters = (target.objectFlags & (ObjectFlags.Reference | ObjectFlags.InstantiationExpressionType) || target.symbol.flags & SymbolFlags.Method || target.symbol.flags & SymbolFlags.TypeLiteral) && !target.aliasTypeArguments ? + filter(typeParameters, tp => some(allDeclarations, d => isTypeParameterPossiblyReferenced(tp, d))) : + typeParameters; + links.outerTypeParameters = typeParameters; + } + if (typeParameters.length) { + // We are instantiating an anonymous type that has one or more type parameters in scope. Apply the + // mapper to the type parameters to produce the effective list of type arguments, and compute the + // instantiation cache key from the type IDs of the type arguments. + const combinedMapper = combineTypeMappers(type.mapper, mapper); + const typeArguments = map(typeParameters, t => getMappedType(t, combinedMapper)); + const newAliasSymbol = aliasSymbol || type.aliasSymbol; + const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + const id = (type.objectFlags & ObjectFlags.SingleSignatureType ? "S" : "") + getTypeListId(typeArguments) + getAliasId(newAliasSymbol, newAliasTypeArguments); + if (!target.instantiations) { + target.instantiations = new Map(); + target.instantiations.set(getTypeListId(typeParameters) + getAliasId(target.aliasSymbol, target.aliasTypeArguments), target); + } + let result = target.instantiations.get(id); + if (!result) { + if (type.objectFlags & ObjectFlags.SingleSignatureType) { + result = instantiateAnonymousType(type, mapper); + target.instantiations.set(id, result); + return result; + } + const newMapper = createTypeMapper(typeParameters, typeArguments); + result = target.objectFlags & ObjectFlags.Reference ? createDeferredTypeReference((type as DeferredTypeReference).target, (type as DeferredTypeReference).node, newMapper, newAliasSymbol, newAliasTypeArguments) : + target.objectFlags & ObjectFlags.Mapped ? instantiateMappedType(target as MappedType, newMapper, newAliasSymbol, newAliasTypeArguments) : + instantiateAnonymousType(target, newMapper, newAliasSymbol, newAliasTypeArguments); + target.instantiations.set(id, result); // Set cached result early in case we recursively invoke instantiation while eagerly computing type variable visibility below + const resultObjectFlags = getObjectFlags(result); + if (result.flags & TypeFlags.ObjectFlagsType && !(resultObjectFlags & ObjectFlags.CouldContainTypeVariablesComputed)) { + const resultCouldContainTypeVariables = some(typeArguments, couldContainTypeVariables); // one of the input type arguments might be or contain the result + if (!(getObjectFlags(result) & ObjectFlags.CouldContainTypeVariablesComputed)) { + // if `result` is one of the object types we tried to make (it may not be, due to how `instantiateMappedType` works), we can carry forward the type variable containment check from the input type arguments + if (resultObjectFlags & (ObjectFlags.Mapped | ObjectFlags.Anonymous | ObjectFlags.Reference)) { + (result as ObjectFlagsType).objectFlags |= ObjectFlags.CouldContainTypeVariablesComputed | (resultCouldContainTypeVariables ? ObjectFlags.CouldContainTypeVariables : 0); + } + // If none of the type arguments for the outer type parameters contain type variables, it follows + // that the instantiated type doesn't reference type variables. + // Intrinsics have `CouldContainTypeVariablesComputed` pre-set, so this should only cover unions and intersections resulting from `instantiateMappedType` + else { + (result as ObjectFlagsType).objectFlags |= !resultCouldContainTypeVariables ? ObjectFlags.CouldContainTypeVariablesComputed : 0; + } + } + } + } + return result; + } + return type; + } + + function maybeTypeParameterReference(node: Node) { + return !(node.parent.kind === SyntaxKind.TypeReference && (node.parent as TypeReferenceNode).typeArguments && node === (node.parent as TypeReferenceNode).typeName || + node.parent.kind === SyntaxKind.ImportType && (node.parent as ImportTypeNode).typeArguments && node === (node.parent as ImportTypeNode).qualifier); + } + + function isTypeParameterPossiblyReferenced(tp: TypeParameter, node: Node) { + // If the type parameter doesn't have exactly one declaration, if there are intervening statement blocks + // between the node and the type parameter declaration, if the node contains actual references to the + // type parameter, or if the node contains type queries that we can't prove couldn't contain references to the type parameter, + // we consider the type parameter possibly referenced. + if (tp.symbol && tp.symbol.declarations && tp.symbol.declarations.length === 1) { + const container = tp.symbol.declarations[0].parent; + for (let n = node; n !== container; n = n.parent) { + if (!n || n.kind === SyntaxKind.Block || n.kind === SyntaxKind.ConditionalType && forEachChild((n as ConditionalTypeNode).extendsType, containsReference)) { + return true; + } + } + return containsReference(node); + } + return true; + function containsReference(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.ThisType: + return !!tp.isThisType; + case SyntaxKind.Identifier: + return !tp.isThisType && isPartOfTypeNode(node) && maybeTypeParameterReference(node) && + getTypeFromTypeNodeWorker(node as TypeNode) === tp; // use worker because we're looking for === equality + case SyntaxKind.TypeQuery: + const entityName = (node as TypeQueryNode).exprName; + const firstIdentifier = getFirstIdentifier(entityName); + if (!isThisIdentifier(firstIdentifier)) { // Don't attempt to analyze typeof this.xxx + const firstIdentifierSymbol = getResolvedSymbol(firstIdentifier); + const tpDeclaration = tp.symbol.declarations![0]; // There is exactly one declaration, otherwise `containsReference` is not called + const tpScope = tpDeclaration.kind === SyntaxKind.TypeParameter ? tpDeclaration.parent : // Type parameter is a regular type parameter, e.g. foo + tp.isThisType ? tpDeclaration : // Type parameter is the this type, and its declaration is the class declaration. + undefined; // Type parameter's declaration was unrecognized, e.g. comes from JSDoc annotation. + if (firstIdentifierSymbol.declarations && tpScope) { + return some(firstIdentifierSymbol.declarations, idDecl => isNodeDescendantOf(idDecl, tpScope)) || + some((node as TypeQueryNode).typeArguments, containsReference); + } + } + return true; + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + return !(node as FunctionLikeDeclaration).type && !!(node as FunctionLikeDeclaration).body || + some((node as FunctionLikeDeclaration).typeParameters, containsReference) || + some((node as FunctionLikeDeclaration).parameters, containsReference) || + !!(node as FunctionLikeDeclaration).type && containsReference((node as FunctionLikeDeclaration).type!); + } + return !!forEachChild(node, containsReference); + } + } + + function getHomomorphicTypeVariable(type: MappedType) { + const constraintType = getConstraintTypeFromMappedType(type); + if (constraintType.flags & TypeFlags.Index) { + const typeVariable = getActualTypeVariable((constraintType as IndexType).type); + if (typeVariable.flags & TypeFlags.TypeParameter) { + return typeVariable as TypeParameter; + } + } + return undefined; + } + + function instantiateMappedType(type: MappedType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + // For a homomorphic mapped type { [P in keyof T]: X }, where T is some type variable, the mapping + // operation depends on T as follows: + // * If T is a primitive type no mapping is performed and the result is simply T. + // * If T is a union type we distribute the mapped type over the union. + // * If T is an array we map to an array where the element type has been transformed. + // * If T is a tuple we map to a tuple where the element types have been transformed. + // * If T is an intersection of array or tuple types we map to an intersection of transformed array or tuple types. + // * Otherwise we map to an object type where the type of each property has been transformed. + // For example, when T is instantiated to a union type A | B, we produce { [P in keyof A]: X } | + // { [P in keyof B]: X }, and when when T is instantiated to a union type A | undefined, we produce + // { [P in keyof A]: X } | undefined. + const typeVariable = getHomomorphicTypeVariable(type); + if (typeVariable) { + const mappedTypeVariable = instantiateType(typeVariable, mapper); + if (typeVariable !== mappedTypeVariable) { + return mapTypeWithAlias(getReducedType(mappedTypeVariable), instantiateConstituent, aliasSymbol, aliasTypeArguments); + } + } + // If the constraint type of the instantiation is the wildcard type, return the wildcard type. + return instantiateType(getConstraintTypeFromMappedType(type), mapper) === wildcardType ? wildcardType : instantiateAnonymousType(type, mapper, aliasSymbol, aliasTypeArguments); + + function instantiateConstituent(t: Type): Type { + if (t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.InstantiableNonPrimitive | TypeFlags.Object | TypeFlags.Intersection) && t !== wildcardType && !isErrorType(t)) { + if (!type.declaration.nameType) { + let constraint; + if ( + isArrayType(t) || t.flags & TypeFlags.Any && findResolutionCycleStartIndex(typeVariable!, TypeSystemPropertyName.ImmediateBaseConstraint) < 0 && + (constraint = getConstraintOfTypeParameter(typeVariable!)) && everyType(constraint, isArrayOrTupleType) + ) { + return instantiateMappedArrayType(t, type, prependTypeMapping(typeVariable!, t, mapper)); + } + if (isTupleType(t)) { + return instantiateMappedTupleType(t, type, typeVariable!, mapper); + } + if (isArrayOrTupleOrIntersection(t)) { + return getIntersectionType(map((t as IntersectionType).types, instantiateConstituent)); + } + } + return instantiateAnonymousType(type, prependTypeMapping(typeVariable!, t, mapper)); + } + return t; + } + } + + function getModifiedReadonlyState(state: boolean, modifiers: MappedTypeModifiers) { + return modifiers & MappedTypeModifiers.IncludeReadonly ? true : modifiers & MappedTypeModifiers.ExcludeReadonly ? false : state; + } + + function instantiateMappedTupleType(tupleType: TupleTypeReference, mappedType: MappedType, typeVariable: TypeVariable, mapper: TypeMapper) { + // We apply the mapped type's template type to each of the fixed part elements. For variadic elements, we + // apply the mapped type itself to the variadic element type. For other elements in the variable part of the + // tuple, we surround the element type with an array type and apply the mapped type to that. This ensures + // that we get sequential property key types for the fixed part of the tuple, and property key type number + // for the remaining elements. For example + // + // type Keys = { [K in keyof T]: K }; + // type Foo = Keys<[string, string, ...T, string]>; // ["0", "1", ...Keys, number] + // + const elementFlags = tupleType.target.elementFlags; + const fixedLength = tupleType.target.fixedLength; + const fixedMapper = fixedLength ? prependTypeMapping(typeVariable, tupleType, mapper) : mapper; + const newElementTypes = map(getElementTypes(tupleType), (type, i) => { + const flags = elementFlags[i]; + return i < fixedLength ? instantiateMappedTypeTemplate(mappedType, getStringLiteralType("" + i), !!(flags & ElementFlags.Optional), fixedMapper) : + flags & ElementFlags.Variadic ? instantiateType(mappedType, prependTypeMapping(typeVariable, type, mapper)) : + getElementTypeOfArrayType(instantiateType(mappedType, prependTypeMapping(typeVariable, createArrayType(type), mapper))) ?? unknownType; + }); + const modifiers = getMappedTypeModifiers(mappedType); + const newElementFlags = modifiers & MappedTypeModifiers.IncludeOptional ? map(elementFlags, f => f & ElementFlags.Required ? ElementFlags.Optional : f) : + modifiers & MappedTypeModifiers.ExcludeOptional ? map(elementFlags, f => f & ElementFlags.Optional ? ElementFlags.Required : f) : + elementFlags; + const newReadonly = getModifiedReadonlyState(tupleType.target.readonly, getMappedTypeModifiers(mappedType)); + return contains(newElementTypes, errorType) ? errorType : + createTupleType(newElementTypes, newElementFlags, newReadonly, tupleType.target.labeledElementDeclarations); + } + + function instantiateMappedArrayType(arrayType: Type, mappedType: MappedType, mapper: TypeMapper) { + const elementType = instantiateMappedTypeTemplate(mappedType, numberType, /*isOptional*/ true, mapper); + return isErrorType(elementType) ? errorType : + createArrayType(elementType, getModifiedReadonlyState(isReadonlyArrayType(arrayType), getMappedTypeModifiers(mappedType))); + } + + function instantiateMappedTypeTemplate(type: MappedType, key: Type, isOptional: boolean, mapper: TypeMapper) { + const templateMapper = appendTypeMapping(mapper, getTypeParameterFromMappedType(type), key); + const propType = instantiateType(getTemplateTypeFromMappedType(type.target as MappedType || type), templateMapper); + const modifiers = getMappedTypeModifiers(type); + return strictNullChecks && modifiers & MappedTypeModifiers.IncludeOptional && !maybeTypeOfKind(propType, TypeFlags.Undefined | TypeFlags.Void) ? getOptionalType(propType, /*isProperty*/ true) : + strictNullChecks && modifiers & MappedTypeModifiers.ExcludeOptional && isOptional ? getTypeWithFacts(propType, TypeFacts.NEUndefined) : + propType; + } + + function instantiateAnonymousType(type: AnonymousType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): AnonymousType { + Debug.assert(type.symbol, "anonymous type must have symbol to be instantiated"); + const result = createObjectType(type.objectFlags & ~(ObjectFlags.CouldContainTypeVariablesComputed | ObjectFlags.CouldContainTypeVariables) | ObjectFlags.Instantiated, type.symbol) as AnonymousType; + if (type.objectFlags & ObjectFlags.Mapped) { + (result as MappedType).declaration = (type as MappedType).declaration; + // C.f. instantiateSignature + const origTypeParameter = getTypeParameterFromMappedType(type as MappedType); + const freshTypeParameter = cloneTypeParameter(origTypeParameter); + (result as MappedType).typeParameter = freshTypeParameter; + mapper = combineTypeMappers(makeUnaryTypeMapper(origTypeParameter, freshTypeParameter), mapper); + freshTypeParameter.mapper = mapper; + } + if (type.objectFlags & ObjectFlags.InstantiationExpressionType) { + (result as InstantiationExpressionType).node = (type as InstantiationExpressionType).node; + } + if (type.objectFlags & ObjectFlags.SingleSignatureType) { + (result as SingleSignatureType).outerTypeParameters = (type as SingleSignatureType).outerTypeParameters; + } + result.target = type; + result.mapper = mapper; + result.aliasSymbol = aliasSymbol || type.aliasSymbol; + result.aliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + result.objectFlags |= result.aliasTypeArguments ? getPropagatingFlagsOfTypes(result.aliasTypeArguments) : 0; + return result; + } + + function getConditionalTypeInstantiation(type: ConditionalType, mapper: TypeMapper, forConstraint: boolean, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + const root = type.root; + if (root.outerTypeParameters) { + // We are instantiating a conditional type that has one or more type parameters in scope. Apply the + // mapper to the type parameters to produce the effective list of type arguments, and compute the + // instantiation cache key from the type IDs of the type arguments. + const typeArguments = map(root.outerTypeParameters, t => getMappedType(t, mapper)); + const id = (forConstraint ? "C" : "") + getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments); + let result = root.instantiations!.get(id); + if (!result) { + const newMapper = createTypeMapper(root.outerTypeParameters, typeArguments); + const checkType = root.checkType; + const distributionType = root.isDistributive ? getReducedType(getMappedType(checkType, newMapper)) : undefined; + // Distributive conditional types are distributed over union types. For example, when the + // distributive conditional type T extends U ? X : Y is instantiated with A | B for T, the + // result is (A extends U ? X : Y) | (B extends U ? X : Y). + result = distributionType && checkType !== distributionType && distributionType.flags & (TypeFlags.Union | TypeFlags.Never) ? + mapTypeWithAlias(distributionType, t => getConditionalType(root, prependTypeMapping(checkType, t, newMapper), forConstraint), aliasSymbol, aliasTypeArguments) : + getConditionalType(root, newMapper, forConstraint, aliasSymbol, aliasTypeArguments); + root.instantiations!.set(id, result); + } + return result; + } + return type; + } + + function instantiateType(type: Type, mapper: TypeMapper | undefined): Type; + function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined; + function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined { + return type && mapper ? instantiateTypeWithAlias(type, mapper, /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined) : type; + } + + function instantiateTypeWithAlias(type: Type, mapper: TypeMapper, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined): Type { + if (!couldContainTypeVariables(type)) { + return type; + } + if (instantiationDepth === 100 || instantiationCount >= 5000000) { + // We have reached 100 recursive type instantiations, or 5M type instantiations caused by the same statement + // or expression. There is a very high likelyhood we're dealing with a combination of infinite generic types + // that perpetually generate new type identities, so we stop the recursion here by yielding the error type. + tracing?.instant(tracing.Phase.CheckTypes, "instantiateType_DepthLimit", { typeId: type.id, instantiationDepth, instantiationCount }); + error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite); + return errorType; + } + totalInstantiationCount++; + instantiationCount++; + instantiationDepth++; + const result = instantiateTypeWorker(type, mapper, aliasSymbol, aliasTypeArguments); + instantiationDepth--; + return result; + } + + function instantiateTypeWorker(type: Type, mapper: TypeMapper, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined): Type { + const flags = type.flags; + if (flags & TypeFlags.TypeParameter) { + return getMappedType(type, mapper); + } + if (flags & TypeFlags.Object) { + const objectFlags = (type as ObjectType).objectFlags; + if (objectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous | ObjectFlags.Mapped)) { + if (objectFlags & ObjectFlags.Reference && !(type as TypeReference).node) { + const resolvedTypeArguments = (type as TypeReference).resolvedTypeArguments; + const newTypeArguments = instantiateTypes(resolvedTypeArguments, mapper); + return newTypeArguments !== resolvedTypeArguments ? createNormalizedTypeReference((type as TypeReference).target, newTypeArguments) : type; + } + if (objectFlags & ObjectFlags.ReverseMapped) { + return instantiateReverseMappedType(type as ReverseMappedType, mapper); + } + return getObjectTypeInstantiation(type as TypeReference | AnonymousType | MappedType, mapper, aliasSymbol, aliasTypeArguments); + } + return type; + } + if (flags & TypeFlags.UnionOrIntersection) { + const origin = type.flags & TypeFlags.Union ? (type as UnionType).origin : undefined; + const types = origin && origin.flags & TypeFlags.UnionOrIntersection ? (origin as UnionOrIntersectionType).types : (type as UnionOrIntersectionType).types; + const newTypes = instantiateTypes(types, mapper); + if (newTypes === types && aliasSymbol === type.aliasSymbol) { + return type; + } + const newAliasSymbol = aliasSymbol || type.aliasSymbol; + const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + return flags & TypeFlags.Intersection || origin && origin.flags & TypeFlags.Intersection ? + getIntersectionType(newTypes, IntersectionFlags.None, newAliasSymbol, newAliasTypeArguments) : + getUnionType(newTypes, UnionReduction.Literal, newAliasSymbol, newAliasTypeArguments); + } + if (flags & TypeFlags.Index) { + return getIndexType(instantiateType((type as IndexType).type, mapper)); + } + if (flags & TypeFlags.TemplateLiteral) { + return getTemplateLiteralType((type as TemplateLiteralType).texts, instantiateTypes((type as TemplateLiteralType).types, mapper)); + } + if (flags & TypeFlags.StringMapping) { + return getStringMappingType((type as StringMappingType).symbol, instantiateType((type as StringMappingType).type, mapper)); + } + if (flags & TypeFlags.IndexedAccess) { + const newAliasSymbol = aliasSymbol || type.aliasSymbol; + const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + return getIndexedAccessType(instantiateType((type as IndexedAccessType).objectType, mapper), instantiateType((type as IndexedAccessType).indexType, mapper), (type as IndexedAccessType).accessFlags, /*accessNode*/ undefined, newAliasSymbol, newAliasTypeArguments); + } + if (flags & TypeFlags.Conditional) { + return getConditionalTypeInstantiation(type as ConditionalType, combineTypeMappers((type as ConditionalType).mapper, mapper), /*forConstraint*/ false, aliasSymbol, aliasTypeArguments); + } + if (flags & TypeFlags.Substitution) { + const newBaseType = instantiateType((type as SubstitutionType).baseType, mapper); + if (isNoInferType(type)) { + return getNoInferType(newBaseType); + } + const newConstraint = instantiateType((type as SubstitutionType).constraint, mapper); + // A substitution type originates in the true branch of a conditional type and can be resolved + // to just the base type in the same cases as the conditional type resolves to its true branch + // (because the base type is then known to satisfy the constraint). + if (newBaseType.flags & TypeFlags.TypeVariable && isGenericType(newConstraint)) { + return getSubstitutionType(newBaseType, newConstraint); + } + if (newConstraint.flags & TypeFlags.AnyOrUnknown || isTypeAssignableTo(getRestrictiveInstantiation(newBaseType), getRestrictiveInstantiation(newConstraint))) { + return newBaseType; + } + return newBaseType.flags & TypeFlags.TypeVariable ? getSubstitutionType(newBaseType, newConstraint) : getIntersectionType([newConstraint, newBaseType]); + } + return type; + } + + function instantiateReverseMappedType(type: ReverseMappedType, mapper: TypeMapper) { + const innerMappedType = instantiateType(type.mappedType, mapper); + if (!(getObjectFlags(innerMappedType) & ObjectFlags.Mapped)) { + return type; + } + const innerIndexType = instantiateType(type.constraintType, mapper); + if (!(innerIndexType.flags & TypeFlags.Index)) { + return type; + } + const instantiated = inferTypeForHomomorphicMappedType( + instantiateType(type.source, mapper), + innerMappedType as MappedType, + innerIndexType as IndexType, + ); + if (instantiated) { + return instantiated; + } + return type; // Nested invocation of `inferTypeForHomomorphicMappedType` or the `source` instantiated into something unmappable + } + + function getPermissiveInstantiation(type: Type) { + return type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never) ? type : + type.permissiveInstantiation || (type.permissiveInstantiation = instantiateType(type, permissiveMapper)); + } + + function getRestrictiveInstantiation(type: Type) { + if (type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never)) { + return type; + } + if (type.restrictiveInstantiation) { + return type.restrictiveInstantiation; + } + type.restrictiveInstantiation = instantiateType(type, restrictiveMapper); + // We set the following so we don't attempt to set the restrictive instance of a restrictive instance + // which is redundant - we'll produce new type identities, but all type params have already been mapped. + // This also gives us a way to detect restrictive instances upon comparisons and _disable_ the "distributeive constraint" + // assignability check for them, which is distinctly unsafe, as once you have a restrctive instance, all the type parameters + // are constrained to `unknown` and produce tons of false positives/negatives! + type.restrictiveInstantiation.restrictiveInstantiation = type.restrictiveInstantiation; + return type.restrictiveInstantiation; + } + + function instantiateIndexInfo(info: IndexInfo, mapper: TypeMapper) { + return createIndexInfo(info.keyType, instantiateType(info.type, mapper), info.isReadonly, info.declaration); + } + + // Returns true if the given expression contains (at any level of nesting) a function or arrow expression + // that is subject to contextual typing. + function isContextSensitive(node: Expression | MethodDeclaration | ObjectLiteralElementLike | JsxAttributeLike | JsxChild): boolean { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + switch (node.kind) { + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.FunctionDeclaration: // Function declarations can have context when annotated with a jsdoc @type + return isContextSensitiveFunctionLikeDeclaration(node as FunctionExpression | ArrowFunction | MethodDeclaration); + case SyntaxKind.ObjectLiteralExpression: + return some((node as ObjectLiteralExpression).properties, isContextSensitive); + case SyntaxKind.ArrayLiteralExpression: + return some((node as ArrayLiteralExpression).elements, isContextSensitive); + case SyntaxKind.ConditionalExpression: + return isContextSensitive((node as ConditionalExpression).whenTrue) || + isContextSensitive((node as ConditionalExpression).whenFalse); + case SyntaxKind.BinaryExpression: + return ((node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken || (node as BinaryExpression).operatorToken.kind === SyntaxKind.QuestionQuestionToken) && + (isContextSensitive((node as BinaryExpression).left) || isContextSensitive((node as BinaryExpression).right)); + case SyntaxKind.PropertyAssignment: + return isContextSensitive((node as PropertyAssignment).initializer); + case SyntaxKind.ParenthesizedExpression: + return isContextSensitive((node as ParenthesizedExpression).expression); + case SyntaxKind.JsxAttributes: + return some((node as JsxAttributes).properties, isContextSensitive) || isJsxOpeningElement(node.parent) && some(node.parent.parent.children, isContextSensitive); + case SyntaxKind.JsxAttribute: { + // If there is no initializer, JSX attribute has a boolean value of true which is not context sensitive. + const { initializer } = node as JsxAttribute; + return !!initializer && isContextSensitive(initializer); + } + case SyntaxKind.JsxExpression: { + // It is possible to that node.expression is undefined (e.g

]: X }, to simply N. This however presumes + // that N distributes over union types, i.e. that N is equivalent to N | N | N. Specifically, we only + // want to perform the reduction when the name type of a mapped type is distributive with respect to the type variable + // introduced by the 'in' clause of the mapped type. Note that non-generic types are considered to be distributive because + // they're the same type regardless of what's being distributed over. + function hasDistributiveNameType(mappedType: MappedType) { + const typeVariable = getTypeParameterFromMappedType(mappedType); + return isDistributive(getNameTypeFromMappedType(mappedType) || typeVariable); + function isDistributive(type: Type): boolean { + return type.flags & (TypeFlags.AnyOrUnknown | TypeFlags.Primitive | TypeFlags.Never | TypeFlags.TypeParameter | TypeFlags.Object | TypeFlags.NonPrimitive) ? true : + type.flags & TypeFlags.Conditional ? (type as ConditionalType).root.isDistributive && (type as ConditionalType).checkType === typeVariable : + type.flags & (TypeFlags.UnionOrIntersection | TypeFlags.TemplateLiteral) ? every((type as UnionOrIntersectionType | TemplateLiteralType).types, isDistributive) : + type.flags & TypeFlags.IndexedAccess ? isDistributive((type as IndexedAccessType).objectType) && isDistributive((type as IndexedAccessType).indexType) : + type.flags & TypeFlags.Substitution ? isDistributive((type as SubstitutionType).baseType) && isDistributive((type as SubstitutionType).constraint) : + type.flags & TypeFlags.StringMapping ? isDistributive((type as StringMappingType).type) : + false; + } + } + + function getLiteralTypeFromPropertyName(name: PropertyName | JsxAttributeName) { + if (isPrivateIdentifier(name)) { + return neverType; + } + if (isNumericLiteral(name)) { + return getRegularTypeOfLiteralType(checkExpression(name)); + } + if (isComputedPropertyName(name)) { + return getRegularTypeOfLiteralType(checkComputedPropertyName(name)); + } + const propertyName = getPropertyNameForPropertyNameNode(name); + if (propertyName !== undefined) { + return getStringLiteralType(unescapeLeadingUnderscores(propertyName)); + } + if (isExpression(name)) { + return getRegularTypeOfLiteralType(checkExpression(name)); + } + return neverType; + } + + function getLiteralTypeFromProperty(prop: Symbol, include: TypeFlags, includeNonPublic?: boolean) { + if (includeNonPublic || !(getDeclarationModifierFlagsFromSymbol(prop) & ModifierFlags.NonPublicAccessibilityModifier)) { + let type = getSymbolLinks(getLateBoundSymbol(prop)).nameType; + if (!type) { + const name = getNameOfDeclaration(prop.valueDeclaration) as PropertyName | JsxAttributeName; + type = prop.escapedName === InternalSymbolName.Default ? getStringLiteralType("default") : + name && getLiteralTypeFromPropertyName(name) || (!isKnownSymbol(prop) ? getStringLiteralType(symbolName(prop)) : undefined); + } + if (type && type.flags & include) { + return type; + } + } + return neverType; + } + + function isKeyTypeIncluded(keyType: Type, include: TypeFlags): boolean { + return !!(keyType.flags & include || keyType.flags & TypeFlags.Intersection && some((keyType as IntersectionType).types, t => isKeyTypeIncluded(t, include))); + } + + function getLiteralTypeFromProperties(type: Type, include: TypeFlags, includeOrigin: boolean) { + const origin = includeOrigin && (getObjectFlags(type) & (ObjectFlags.ClassOrInterface | ObjectFlags.Reference) || type.aliasSymbol) ? createOriginIndexType(type) : undefined; + const propertyTypes = map(getPropertiesOfType(type), prop => getLiteralTypeFromProperty(prop, include)); + const indexKeyTypes = map(getIndexInfosOfType(type), info => + info !== enumNumberIndexInfo && isKeyTypeIncluded(info.keyType, include) ? + info.keyType === stringType && include & TypeFlags.Number ? stringOrNumberType : info.keyType : neverType); + return getUnionType(concatenate(propertyTypes, indexKeyTypes), UnionReduction.Literal, /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined, origin); + } + + function shouldDeferIndexType(type: Type, indexFlags = IndexFlags.None) { + return !!(type.flags & TypeFlags.InstantiableNonPrimitive || + isGenericTupleType(type) || + isGenericMappedType(type) && (!hasDistributiveNameType(type) || getMappedTypeNameTypeKind(type) === MappedTypeNameTypeKind.Remapping) || + type.flags & TypeFlags.Union && !(indexFlags & IndexFlags.NoReducibleCheck) && isGenericReducibleType(type) || + type.flags & TypeFlags.Intersection && maybeTypeOfKind(type, TypeFlags.Instantiable) && some((type as IntersectionType).types, isEmptyAnonymousObjectType)); + } + + function getIndexType(type: Type, indexFlags = IndexFlags.None): Type { + type = getReducedType(type); + return isNoInferType(type) ? getNoInferType(getIndexType((type as SubstitutionType).baseType, indexFlags)) : + shouldDeferIndexType(type, indexFlags) ? getIndexTypeForGenericType(type as InstantiableType | UnionOrIntersectionType, indexFlags) : + type.flags & TypeFlags.Union ? getIntersectionType(map((type as UnionType).types, t => getIndexType(t, indexFlags))) : + type.flags & TypeFlags.Intersection ? getUnionType(map((type as IntersectionType).types, t => getIndexType(t, indexFlags))) : + getObjectFlags(type) & ObjectFlags.Mapped ? getIndexTypeForMappedType(type as MappedType, indexFlags) : + type === wildcardType ? wildcardType : + type.flags & TypeFlags.Unknown ? neverType : + type.flags & (TypeFlags.Any | TypeFlags.Never) ? stringNumberSymbolType : + getLiteralTypeFromProperties(type, (indexFlags & IndexFlags.NoIndexSignatures ? TypeFlags.StringLiteral : TypeFlags.StringLike) | (indexFlags & IndexFlags.StringsOnly ? 0 : TypeFlags.NumberLike | TypeFlags.ESSymbolLike), indexFlags === IndexFlags.None); + } + + function getExtractStringType(type: Type) { + const extractTypeAlias = getGlobalExtractSymbol(); + return extractTypeAlias ? getTypeAliasInstantiation(extractTypeAlias, [type, stringType]) : stringType; + } + + function getIndexTypeOrString(type: Type): Type { + const indexType = getExtractStringType(getIndexType(type)); + return indexType.flags & TypeFlags.Never ? stringType : indexType; + } + + function getTypeFromTypeOperatorNode(node: TypeOperatorNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + switch (node.operator) { + case SyntaxKind.KeyOfKeyword: + links.resolvedType = getIndexType(getTypeFromTypeNode(node.type)); + break; + case SyntaxKind.UniqueKeyword: + links.resolvedType = node.type.kind === SyntaxKind.SymbolKeyword + ? getESSymbolLikeTypeForNode(walkUpParenthesizedTypes(node.parent)) + : errorType; + break; + case SyntaxKind.ReadonlyKeyword: + links.resolvedType = getTypeFromTypeNode(node.type); + break; + default: + Debug.assertNever(node.operator); + } + } + return links.resolvedType; + } + + function getTypeFromTemplateTypeNode(node: TemplateLiteralTypeNode) { + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getTemplateLiteralType( + [node.head.text, ...map(node.templateSpans, span => span.literal.text)], + map(node.templateSpans, span => getTypeFromTypeNode(span.type)), + ); + } + return links.resolvedType; + } + + function getTemplateLiteralType(texts: readonly string[], types: readonly Type[]): Type { + const unionIndex = findIndex(types, t => !!(t.flags & (TypeFlags.Never | TypeFlags.Union))); + if (unionIndex >= 0) { + return checkCrossProductUnion(types) ? + mapType(types[unionIndex], t => getTemplateLiteralType(texts, replaceElement(types, unionIndex, t))) : + errorType; + } + if (contains(types, wildcardType)) { + return wildcardType; + } + const newTypes: Type[] = []; + const newTexts: string[] = []; + let text = texts[0]; + if (!addSpans(texts, types)) { + return stringType; + } + if (newTypes.length === 0) { + return getStringLiteralType(text); + } + newTexts.push(text); + if (every(newTexts, t => t === "")) { + if (every(newTypes, t => !!(t.flags & TypeFlags.String))) { + return stringType; + } + // Normalize `${Mapping}` into Mapping + if (newTypes.length === 1 && isPatternLiteralType(newTypes[0])) { + return newTypes[0]; + } + } + const id = `${getTypeListId(newTypes)}|${map(newTexts, t => t.length).join(",")}|${newTexts.join("")}`; + let type = templateLiteralTypes.get(id); + if (!type) { + templateLiteralTypes.set(id, type = createTemplateLiteralType(newTexts, newTypes)); + } + return type; + + function addSpans(texts: readonly string[], types: readonly Type[]): boolean { + for (let i = 0; i < types.length; i++) { + const t = types[i]; + if (t.flags & (TypeFlags.Literal | TypeFlags.Null | TypeFlags.Undefined)) { + text += getTemplateStringForType(t) || ""; + text += texts[i + 1]; + } + else if (t.flags & TypeFlags.TemplateLiteral) { + text += (t as TemplateLiteralType).texts[0]; + if (!addSpans((t as TemplateLiteralType).texts, (t as TemplateLiteralType).types)) return false; + text += texts[i + 1]; + } + else if (isGenericIndexType(t) || isPatternLiteralPlaceholderType(t)) { + newTypes.push(t); + newTexts.push(text); + text = texts[i + 1]; + } + else { + return false; + } + } + return true; + } + } + + function getTemplateStringForType(type: Type) { + return type.flags & TypeFlags.StringLiteral ? (type as StringLiteralType).value : + type.flags & TypeFlags.NumberLiteral ? "" + (type as NumberLiteralType).value : + type.flags & TypeFlags.BigIntLiteral ? pseudoBigIntToString((type as BigIntLiteralType).value) : + type.flags & (TypeFlags.BooleanLiteral | TypeFlags.Nullable) ? (type as IntrinsicType).intrinsicName : + undefined; + } + + function createTemplateLiteralType(texts: readonly string[], types: readonly Type[]) { + const type = createType(TypeFlags.TemplateLiteral) as TemplateLiteralType; + type.texts = texts; + type.types = types; + return type; + } + + function getStringMappingType(symbol: Symbol, type: Type): Type { + return type.flags & (TypeFlags.Union | TypeFlags.Never) ? mapType(type, t => getStringMappingType(symbol, t)) : + type.flags & TypeFlags.StringLiteral ? getStringLiteralType(applyStringMapping(symbol, (type as StringLiteralType).value)) : + type.flags & TypeFlags.TemplateLiteral ? getTemplateLiteralType(...applyTemplateStringMapping(symbol, (type as TemplateLiteralType).texts, (type as TemplateLiteralType).types)) : + // Mapping> === Mapping + type.flags & TypeFlags.StringMapping && symbol === type.symbol ? type : + type.flags & (TypeFlags.Any | TypeFlags.String | TypeFlags.StringMapping) || isGenericIndexType(type) ? getStringMappingTypeForGenericType(symbol, type) : + // This handles Mapping<`${number}`> and Mapping<`${bigint}`> + isPatternLiteralPlaceholderType(type) ? getStringMappingTypeForGenericType(symbol, getTemplateLiteralType(["", ""], [type])) : + type; + } + + function applyStringMapping(symbol: Symbol, str: string) { + switch (intrinsicTypeKinds.get(symbol.escapedName as string)) { + case IntrinsicTypeKind.Uppercase: + return str.toUpperCase(); + case IntrinsicTypeKind.Lowercase: + return str.toLowerCase(); + case IntrinsicTypeKind.Capitalize: + return str.charAt(0).toUpperCase() + str.slice(1); + case IntrinsicTypeKind.Uncapitalize: + return str.charAt(0).toLowerCase() + str.slice(1); + } + return str; + } + + function applyTemplateStringMapping(symbol: Symbol, texts: readonly string[], types: readonly Type[]): [texts: readonly string[], types: readonly Type[]] { + switch (intrinsicTypeKinds.get(symbol.escapedName as string)) { + case IntrinsicTypeKind.Uppercase: + return [texts.map(t => t.toUpperCase()), types.map(t => getStringMappingType(symbol, t))]; + case IntrinsicTypeKind.Lowercase: + return [texts.map(t => t.toLowerCase()), types.map(t => getStringMappingType(symbol, t))]; + case IntrinsicTypeKind.Capitalize: + return [texts[0] === "" ? texts : [texts[0].charAt(0).toUpperCase() + texts[0].slice(1), ...texts.slice(1)], texts[0] === "" ? [getStringMappingType(symbol, types[0]), ...types.slice(1)] : types]; + case IntrinsicTypeKind.Uncapitalize: + return [texts[0] === "" ? texts : [texts[0].charAt(0).toLowerCase() + texts[0].slice(1), ...texts.slice(1)], texts[0] === "" ? [getStringMappingType(symbol, types[0]), ...types.slice(1)] : types]; + } + return [texts, types]; + } + + function getStringMappingTypeForGenericType(symbol: Symbol, type: Type): Type { + const id = `${getSymbolId(symbol)},${getTypeId(type)}`; + let result = stringMappingTypes.get(id); + if (!result) { + stringMappingTypes.set(id, result = createStringMappingType(symbol, type)); + } + return result; + } + + function createStringMappingType(symbol: Symbol, type: Type) { + const result = createTypeWithSymbol(TypeFlags.StringMapping, symbol) as StringMappingType; + result.type = type; + return result; + } + + function createIndexedAccessType(objectType: Type, indexType: Type, accessFlags: AccessFlags, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined) { + const type = createType(TypeFlags.IndexedAccess) as IndexedAccessType; + type.objectType = objectType; + type.indexType = indexType; + type.accessFlags = accessFlags; + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = aliasTypeArguments; + return type; + } + + /** + * Returns if a type is or consists of a JSLiteral object type + * In addition to objects which are directly literals, + * * unions where every element is a jsliteral + * * intersections where at least one element is a jsliteral + * * and instantiable types constrained to a jsliteral + * Should all count as literals and not print errors on access or assignment of possibly existing properties. + * This mirrors the behavior of the index signature propagation, to which this behaves similarly (but doesn't affect assignability or inference). + */ + function isJSLiteralType(type: Type): boolean { + if (noImplicitAny) { + return false; // Flag is meaningless under `noImplicitAny` mode + } + if (getObjectFlags(type) & ObjectFlags.JSLiteral) { + return true; + } + if (type.flags & TypeFlags.Union) { + return every((type as UnionType).types, isJSLiteralType); + } + if (type.flags & TypeFlags.Intersection) { + return some((type as IntersectionType).types, isJSLiteralType); + } + if (type.flags & TypeFlags.Instantiable) { + const constraint = getResolvedBaseConstraint(type); + return constraint !== type && isJSLiteralType(constraint); + } + return false; + } + + function getPropertyNameFromIndex(indexType: Type, accessNode: PropertyName | ObjectBindingPattern | ArrayBindingPattern | IndexedAccessTypeNode | ElementAccessExpression | SyntheticExpression | undefined) { + return isTypeUsableAsPropertyName(indexType) ? + getPropertyNameFromType(indexType) : + accessNode && isPropertyName(accessNode) ? + // late bound names are handled in the first branch, so here we only need to handle normal names + getPropertyNameForPropertyNameNode(accessNode) : + undefined; + } + + function isUncalledFunctionReference(node: Node, symbol: Symbol) { + if (symbol.flags & (SymbolFlags.Function | SymbolFlags.Method)) { + const parent = findAncestor(node.parent, n => !isAccessExpression(n)) || node.parent; + if (isCallLikeExpression(parent)) { + return isCallOrNewExpression(parent) && isIdentifier(node) && hasMatchingArgument(parent, node); + } + return every(symbol.declarations, d => !isFunctionLike(d) || isDeprecatedDeclaration(d)); + } + return true; + } + + function getPropertyTypeForIndexType(originalObjectType: Type, objectType: Type, indexType: Type, fullIndexType: Type, accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression | undefined, accessFlags: AccessFlags) { + const accessExpression = accessNode && accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode : undefined; + const propName = accessNode && isPrivateIdentifier(accessNode) ? undefined : getPropertyNameFromIndex(indexType, accessNode); + + if (propName !== undefined) { + if (accessFlags & AccessFlags.Contextual) { + return getTypeOfPropertyOfContextualType(objectType, propName) || anyType; + } + const prop = getPropertyOfType(objectType, propName); + if (prop) { + if (accessFlags & AccessFlags.ReportDeprecated && accessNode && prop.declarations && isDeprecatedSymbol(prop) && isUncalledFunctionReference(accessNode, prop)) { + const deprecatedNode = accessExpression?.argumentExpression ?? (isIndexedAccessTypeNode(accessNode) ? accessNode.indexType : accessNode); + addDeprecatedSuggestion(deprecatedNode, prop.declarations, propName as string); + } + if (accessExpression) { + markPropertyAsReferenced(prop, accessExpression, isSelfTypeAccess(accessExpression.expression, objectType.symbol)); + if (isAssignmentToReadonlyEntity(accessExpression, prop, getAssignmentTargetKind(accessExpression))) { + error(accessExpression.argumentExpression, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(prop)); + return undefined; + } + if (accessFlags & AccessFlags.CacheSymbol) { + getNodeLinks(accessNode!).resolvedSymbol = prop; + } + if (isThisPropertyAccessInConstructor(accessExpression, prop)) { + return autoType; + } + } + const propType = accessFlags & AccessFlags.Writing ? getWriteTypeOfSymbol(prop) : getTypeOfSymbol(prop); + return accessExpression && getAssignmentTargetKind(accessExpression) !== AssignmentKind.Definite ? getFlowTypeOfReference(accessExpression, propType) : + accessNode && isIndexedAccessTypeNode(accessNode) && containsMissingType(propType) ? getUnionType([propType, undefinedType]) : + propType; + } + if (everyType(objectType, isTupleType) && isNumericLiteralName(propName)) { + const index = +propName; + if (accessNode && everyType(objectType, t => !((t as TupleTypeReference).target.combinedFlags & ElementFlags.Variable)) && !(accessFlags & AccessFlags.NoTupleBoundsCheck)) { + const indexNode = getIndexNodeForAccessExpression(accessNode); + if (isTupleType(objectType)) { + if (index < 0) { + error(indexNode, Diagnostics.A_tuple_type_cannot_be_indexed_with_a_negative_value); + return undefinedType; + } + error(indexNode, Diagnostics.Tuple_type_0_of_length_1_has_no_element_at_index_2, typeToString(objectType), getTypeReferenceArity(objectType), unescapeLeadingUnderscores(propName)); + } + else { + error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType)); + } + } + if (index >= 0) { + errorIfWritingToReadonlyIndex(getIndexInfoOfType(objectType, numberType)); + return getTupleElementTypeOutOfStartCount(objectType, index, accessFlags & AccessFlags.IncludeUndefined ? missingType : undefined); + } + } + } + if (!(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike)) { + if (objectType.flags & (TypeFlags.Any | TypeFlags.Never)) { + return objectType; + } + // If no index signature is applicable, we default to the string index signature. In effect, this means the string + // index signature applies even when accessing with a symbol-like type. + const indexInfo = getApplicableIndexInfo(objectType, indexType) || getIndexInfoOfType(objectType, stringType); + if (indexInfo) { + if (accessFlags & AccessFlags.NoIndexSignatures && indexInfo.keyType !== numberType) { + if (accessExpression) { + if (accessFlags & AccessFlags.Writing) { + error(accessExpression, Diagnostics.Type_0_is_generic_and_can_only_be_indexed_for_reading, typeToString(originalObjectType)); + } + else { + error(accessExpression, Diagnostics.Type_0_cannot_be_used_to_index_type_1, typeToString(indexType), typeToString(originalObjectType)); + } + } + return undefined; + } + if (accessNode && indexInfo.keyType === stringType && !isTypeAssignableToKind(indexType, TypeFlags.String | TypeFlags.Number)) { + const indexNode = getIndexNodeForAccessExpression(accessNode); + error(indexNode, Diagnostics.Type_0_cannot_be_used_as_an_index_type, typeToString(indexType)); + return accessFlags & AccessFlags.IncludeUndefined ? getUnionType([indexInfo.type, missingType]) : indexInfo.type; + } + errorIfWritingToReadonlyIndex(indexInfo); + // When accessing an enum object with its own type, + // e.g. E[E.A] for enum E { A }, undefined shouldn't + // be included in the result type + if ( + (accessFlags & AccessFlags.IncludeUndefined) && + !(objectType.symbol && + objectType.symbol.flags & (SymbolFlags.RegularEnum | SymbolFlags.ConstEnum) && + (indexType.symbol && + indexType.flags & TypeFlags.EnumLiteral && + getParentOfSymbol(indexType.symbol) === objectType.symbol)) + ) { + return getUnionType([indexInfo.type, missingType]); + } + return indexInfo.type; + } + if (indexType.flags & TypeFlags.Never) { + return neverType; + } + if (isJSLiteralType(objectType)) { + return anyType; + } + if (accessExpression && !isConstEnumObjectType(objectType)) { + if (isObjectLiteralType(objectType)) { + if (noImplicitAny && indexType.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) { + diagnostics.add(createDiagnosticForNode(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as StringLiteralType).value, typeToString(objectType))); + return undefinedType; + } + else if (indexType.flags & (TypeFlags.Number | TypeFlags.String)) { + const types = map((objectType as ResolvedType).properties, property => { + return getTypeOfSymbol(property); + }); + return getUnionType(append(types, undefinedType)); + } + } + + if (objectType.symbol === globalThisSymbol && propName !== undefined && globalThisSymbol.exports!.has(propName) && (globalThisSymbol.exports!.get(propName)!.flags & SymbolFlags.BlockScoped)) { + error(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType)); + } + else if (noImplicitAny && !(accessFlags & AccessFlags.SuppressNoImplicitAnyError)) { + if (propName !== undefined && typeHasStaticProperty(propName, objectType)) { + const typeName = typeToString(objectType); + error(accessExpression, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_to_access_the_static_member_2_instead, propName as string, typeName, typeName + "[" + getTextOfNode(accessExpression.argumentExpression) + "]"); + } + else if (getIndexTypeOfType(objectType, numberType)) { + error(accessExpression.argumentExpression, Diagnostics.Element_implicitly_has_an_any_type_because_index_expression_is_not_of_type_number); + } + else { + let suggestion: string | undefined; + if (propName !== undefined && (suggestion = getSuggestionForNonexistentProperty(propName as string, objectType))) { + if (suggestion !== undefined) { + error(accessExpression.argumentExpression, Diagnostics.Property_0_does_not_exist_on_type_1_Did_you_mean_2, propName as string, typeToString(objectType), suggestion); + } + } + else { + const suggestion = getSuggestionForNonexistentIndexSignature(objectType, accessExpression, indexType); + if (suggestion !== undefined) { + error(accessExpression, Diagnostics.Element_implicitly_has_an_any_type_because_type_0_has_no_index_signature_Did_you_mean_to_call_1, typeToString(objectType), suggestion); + } + else { + let errorInfo: DiagnosticMessageChain | undefined; + if (indexType.flags & TypeFlags.EnumLiteral) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, "[" + typeToString(indexType) + "]", typeToString(objectType)); + } + else if (indexType.flags & TypeFlags.UniqueESSymbol) { + const symbolName = getFullyQualifiedName((indexType as UniqueESSymbolType).symbol, accessExpression); + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, "[" + symbolName + "]", typeToString(objectType)); + } + else if (indexType.flags & TypeFlags.StringLiteral) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as StringLiteralType).value, typeToString(objectType)); + } + else if (indexType.flags & TypeFlags.NumberLiteral) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.Property_0_does_not_exist_on_type_1, (indexType as NumberLiteralType).value, typeToString(objectType)); + } + else if (indexType.flags & (TypeFlags.Number | TypeFlags.String)) { + errorInfo = chainDiagnosticMessages(/*details*/ undefined, Diagnostics.No_index_signature_with_a_parameter_of_type_0_was_found_on_type_1, typeToString(indexType), typeToString(objectType)); + } + + errorInfo = chainDiagnosticMessages( + errorInfo, + Diagnostics.Element_implicitly_has_an_any_type_because_expression_of_type_0_can_t_be_used_to_index_type_1, + typeToString(fullIndexType), + typeToString(objectType), + ); + diagnostics.add(createDiagnosticForNodeFromMessageChain(getSourceFileOfNode(accessExpression), accessExpression, errorInfo)); + } + } + } + } + return undefined; + } + } + if (isJSLiteralType(objectType)) { + return anyType; + } + if (accessNode) { + const indexNode = getIndexNodeForAccessExpression(accessNode); + if (indexType.flags & (TypeFlags.StringLiteral | TypeFlags.NumberLiteral)) { + error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, "" + (indexType as StringLiteralType | NumberLiteralType).value, typeToString(objectType)); + } + else if (indexType.flags & (TypeFlags.String | TypeFlags.Number)) { + error(indexNode, Diagnostics.Type_0_has_no_matching_index_signature_for_type_1, typeToString(objectType), typeToString(indexType)); + } + else { + error(indexNode, Diagnostics.Type_0_cannot_be_used_as_an_index_type, typeToString(indexType)); + } + } + if (isTypeAny(indexType)) { + return indexType; + } + return undefined; + + function errorIfWritingToReadonlyIndex(indexInfo: IndexInfo | undefined): void { + if (indexInfo && indexInfo.isReadonly && accessExpression && (isAssignmentTarget(accessExpression) || isDeleteTarget(accessExpression))) { + error(accessExpression, Diagnostics.Index_signature_in_type_0_only_permits_reading, typeToString(objectType)); + } + } + } + + function getIndexNodeForAccessExpression(accessNode: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression) { + return accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode.argumentExpression : + accessNode.kind === SyntaxKind.IndexedAccessType ? accessNode.indexType : + accessNode.kind === SyntaxKind.ComputedPropertyName ? accessNode.expression : + accessNode; + } + + function isPatternLiteralPlaceholderType(type: Type): boolean { + if (type.flags & TypeFlags.Intersection) { + // Return true if the intersection consists of one or more placeholders and zero or + // more object type tags. + let seenPlaceholder = false; + for (const t of (type as IntersectionType).types) { + if (t.flags & (TypeFlags.Literal | TypeFlags.Nullable) || isPatternLiteralPlaceholderType(t)) { + seenPlaceholder = true; + } + else if (!(t.flags & TypeFlags.Object)) { + return false; + } + } + return seenPlaceholder; + } + return !!(type.flags & (TypeFlags.Any | TypeFlags.String | TypeFlags.Number | TypeFlags.BigInt)) || isPatternLiteralType(type); + } + + function isPatternLiteralType(type: Type) { + // A pattern literal type is a template literal or a string mapping type that contains only + // non-generic pattern literal placeholders. + return !!(type.flags & TypeFlags.TemplateLiteral) && every((type as TemplateLiteralType).types, isPatternLiteralPlaceholderType) || + !!(type.flags & TypeFlags.StringMapping) && isPatternLiteralPlaceholderType((type as StringMappingType).type); + } + + function isGenericStringLikeType(type: Type) { + return !!(type.flags & (TypeFlags.TemplateLiteral | TypeFlags.StringMapping)) && !isPatternLiteralType(type); + } + + function isGenericType(type: Type): boolean { + return !!getGenericObjectFlags(type); + } + + function isGenericObjectType(type: Type): boolean { + return !!(getGenericObjectFlags(type) & ObjectFlags.IsGenericObjectType); + } + + function isGenericIndexType(type: Type): boolean { + return !!(getGenericObjectFlags(type) & ObjectFlags.IsGenericIndexType); + } + + function getGenericObjectFlags(type: Type): ObjectFlags { + if (type.flags & (TypeFlags.UnionOrIntersection)) { + if (!((type as UnionOrIntersectionType).objectFlags & ObjectFlags.IsGenericTypeComputed)) { + (type as UnionOrIntersectionType).objectFlags |= ObjectFlags.IsGenericTypeComputed | + reduceLeft((type as UnionOrIntersectionType).types, (flags, t) => flags | getGenericObjectFlags(t), 0); + } + return (type as UnionOrIntersectionType).objectFlags & ObjectFlags.IsGenericType; + } + if (type.flags & TypeFlags.Substitution) { + if (!((type as SubstitutionType).objectFlags & ObjectFlags.IsGenericTypeComputed)) { + (type as SubstitutionType).objectFlags |= ObjectFlags.IsGenericTypeComputed | + getGenericObjectFlags((type as SubstitutionType).baseType) | getGenericObjectFlags((type as SubstitutionType).constraint); + } + return (type as SubstitutionType).objectFlags & ObjectFlags.IsGenericType; + } + return (type.flags & TypeFlags.InstantiableNonPrimitive || isGenericMappedType(type) || isGenericTupleType(type) ? ObjectFlags.IsGenericObjectType : 0) | + (type.flags & (TypeFlags.InstantiableNonPrimitive | TypeFlags.Index) || isGenericStringLikeType(type) ? ObjectFlags.IsGenericIndexType : 0); + } + + function getSimplifiedType(type: Type, writing: boolean): Type { + return type.flags & TypeFlags.IndexedAccess ? getSimplifiedIndexedAccessType(type as IndexedAccessType, writing) : + type.flags & TypeFlags.Conditional ? getSimplifiedConditionalType(type as ConditionalType, writing) : + type; + } + + function distributeIndexOverObjectType(objectType: Type, indexType: Type, writing: boolean) { + // (T | U)[K] -> T[K] | U[K] (reading) + // (T | U)[K] -> T[K] & U[K] (writing) + // (T & U)[K] -> T[K] & U[K] + if (objectType.flags & TypeFlags.Union || objectType.flags & TypeFlags.Intersection && !shouldDeferIndexType(objectType)) { + const types = map((objectType as UnionOrIntersectionType).types, t => getSimplifiedType(getIndexedAccessType(t, indexType), writing)); + return objectType.flags & TypeFlags.Intersection || writing ? getIntersectionType(types) : getUnionType(types); + } + } + + function distributeObjectOverIndexType(objectType: Type, indexType: Type, writing: boolean) { + // T[A | B] -> T[A] | T[B] (reading) + // T[A | B] -> T[A] & T[B] (writing) + if (indexType.flags & TypeFlags.Union) { + const types = map((indexType as UnionType).types, t => getSimplifiedType(getIndexedAccessType(objectType, t), writing)); + return writing ? getIntersectionType(types) : getUnionType(types); + } + } + + // Transform an indexed access to a simpler form, if possible. Return the simpler form, or return + // the type itself if no transformation is possible. The writing flag indicates that the type is + // the target of an assignment. + function getSimplifiedIndexedAccessType(type: IndexedAccessType, writing: boolean): Type { + const cache = writing ? "simplifiedForWriting" : "simplifiedForReading"; + if (type[cache]) { + return type[cache] === circularConstraintType ? type : type[cache]!; + } + type[cache] = circularConstraintType; + // We recursively simplify the object type as it may in turn be an indexed access type. For example, with + // '{ [P in T]: { [Q in U]: number } }[T][U]' we want to first simplify the inner indexed access type. + const objectType = getSimplifiedType(type.objectType, writing); + const indexType = getSimplifiedType(type.indexType, writing); + // T[A | B] -> T[A] | T[B] (reading) + // T[A | B] -> T[A] & T[B] (writing) + const distributedOverIndex = distributeObjectOverIndexType(objectType, indexType, writing); + if (distributedOverIndex) { + return type[cache] = distributedOverIndex; + } + // Only do the inner distributions if the index can no longer be instantiated to cause index distribution again + if (!(indexType.flags & TypeFlags.Instantiable)) { + // (T | U)[K] -> T[K] | U[K] (reading) + // (T | U)[K] -> T[K] & U[K] (writing) + // (T & U)[K] -> T[K] & U[K] + const distributedOverObject = distributeIndexOverObjectType(objectType, indexType, writing); + if (distributedOverObject) { + return type[cache] = distributedOverObject; + } + } + // So ultimately (reading): + // ((A & B) | C)[K1 | K2] -> ((A & B) | C)[K1] | ((A & B) | C)[K2] -> (A & B)[K1] | C[K1] | (A & B)[K2] | C[K2] -> (A[K1] & B[K1]) | C[K1] | (A[K2] & B[K2]) | C[K2] + + // A generic tuple type indexed by a number exists only when the index type doesn't select a + // fixed element. We simplify to either the combined type of all elements (when the index type + // the actual number type) or to the combined type of all non-fixed elements. + if (isGenericTupleType(objectType) && indexType.flags & TypeFlags.NumberLike) { + const elementType = getElementTypeOfSliceOfTupleType(objectType, indexType.flags & TypeFlags.Number ? 0 : objectType.target.fixedLength, /*endSkipCount*/ 0, writing); + if (elementType) { + return type[cache] = elementType; + } + } + // If the object type is a mapped type { [P in K]: E }, where K is generic, or { [P in K as N]: E }, where + // K is generic and N is assignable to P, instantiate E using a mapper that substitutes the index type for P. + // For example, for an index access { [P in K]: Box }[X], we construct the type Box. + if (isGenericMappedType(objectType)) { + if (getMappedTypeNameTypeKind(objectType) !== MappedTypeNameTypeKind.Remapping) { + return type[cache] = mapType(substituteIndexedMappedType(objectType, type.indexType), t => getSimplifiedType(t, writing)); + } + } + return type[cache] = type; + } + + function getSimplifiedConditionalType(type: ConditionalType, writing: boolean) { + const checkType = type.checkType; + const extendsType = type.extendsType; + const trueType = getTrueTypeFromConditionalType(type); + const falseType = getFalseTypeFromConditionalType(type); + // Simplifications for types of the form `T extends U ? T : never` and `T extends U ? never : T`. + if (falseType.flags & TypeFlags.Never && getActualTypeVariable(trueType) === getActualTypeVariable(checkType)) { + if (checkType.flags & TypeFlags.Any || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true + return getSimplifiedType(trueType, writing); + } + else if (isIntersectionEmpty(checkType, extendsType)) { // Always false + return neverType; + } + } + else if (trueType.flags & TypeFlags.Never && getActualTypeVariable(falseType) === getActualTypeVariable(checkType)) { + if (!(checkType.flags & TypeFlags.Any) && isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(extendsType))) { // Always true + return neverType; + } + else if (checkType.flags & TypeFlags.Any || isIntersectionEmpty(checkType, extendsType)) { // Always false + return getSimplifiedType(falseType, writing); + } + } + return type; + } + + /** + * Invokes union simplification logic to determine if an intersection is considered empty as a union constituent + */ + function isIntersectionEmpty(type1: Type, type2: Type) { + return !!(getUnionType([intersectTypes(type1, type2), neverType]).flags & TypeFlags.Never); + } + + // Given an indexed access on a mapped type of the form { [P in K]: E }[X], return an instantiation of E where P is + // replaced with X. Since this simplification doesn't account for mapped type modifiers, add 'undefined' to the + // resulting type if the mapped type includes a '?' modifier or if the modifiers type indicates that some properties + // are optional. If the modifiers type is generic, conservatively estimate optionality by recursively looking for + // mapped types that include '?' modifiers. + function substituteIndexedMappedType(objectType: MappedType, index: Type) { + const mapper = createTypeMapper([getTypeParameterFromMappedType(objectType)], [index]); + const templateMapper = combineTypeMappers(objectType.mapper, mapper); + const instantiatedTemplateType = instantiateType(getTemplateTypeFromMappedType(objectType.target as MappedType || objectType), templateMapper); + const isOptional = getMappedTypeOptionality(objectType) > 0 || (isGenericType(objectType) ? + getCombinedMappedTypeOptionality(getModifiersTypeFromMappedType(objectType)) > 0 : + couldAccessOptionalProperty(objectType, index)); + return addOptionality(instantiatedTemplateType, /*isProperty*/ true, isOptional); + } + + // Return true if an indexed access with the given object and index types could access an optional property. + function couldAccessOptionalProperty(objectType: Type, indexType: Type) { + const indexConstraint = getBaseConstraintOfType(indexType); + return !!indexConstraint && some(getPropertiesOfType(objectType), p => + !!(p.flags & SymbolFlags.Optional) && + isTypeAssignableTo(getLiteralTypeFromProperty(p, TypeFlags.StringOrNumberLiteralOrUnique), indexConstraint)); + } + + function getIndexedAccessType(objectType: Type, indexType: Type, accessFlags = AccessFlags.None, accessNode?: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + return getIndexedAccessTypeOrUndefined(objectType, indexType, accessFlags, accessNode, aliasSymbol, aliasTypeArguments) || (accessNode ? errorType : unknownType); + } + + function indexTypeLessThan(indexType: Type, limit: number) { + return everyType(indexType, t => { + if (t.flags & TypeFlags.StringOrNumberLiteral) { + const propName = getPropertyNameFromType(t as StringLiteralType | NumberLiteralType); + if (isNumericLiteralName(propName)) { + const index = +propName; + return index >= 0 && index < limit; + } + } + return false; + }); + } + + function getIndexedAccessTypeOrUndefined(objectType: Type, indexType: Type, accessFlags = AccessFlags.None, accessNode?: ElementAccessExpression | IndexedAccessTypeNode | PropertyName | BindingName | SyntheticExpression, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type | undefined { + if (objectType === wildcardType || indexType === wildcardType) { + return wildcardType; + } + objectType = getReducedType(objectType); + // If the object type has a string index signature and no other members we know that the result will + // always be the type of that index signature and we can simplify accordingly. + if (isStringIndexSignatureOnlyType(objectType) && !(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.String | TypeFlags.Number)) { + indexType = stringType; + } + // In noUncheckedIndexedAccess mode, indexed access operations that occur in an expression in a read position and resolve to + // an index signature have 'undefined' included in their type. + if (compilerOptions.noUncheckedIndexedAccess && accessFlags & AccessFlags.ExpressionPosition) accessFlags |= AccessFlags.IncludeUndefined; + // If the index type is generic, or if the object type is generic and doesn't originate in an expression and + // the operation isn't exclusively indexing the fixed (non-variadic) portion of a tuple type, we are performing + // a higher-order index access where we cannot meaningfully access the properties of the object type. Note that + // for a generic T and a non-generic K, we eagerly resolve T[K] if it originates in an expression. This is to + // preserve backwards compatibility. For example, an element access 'this["foo"]' has always been resolved + // eagerly using the constraint type of 'this' at the given location. + if ( + isGenericIndexType(indexType) || (accessNode && accessNode.kind !== SyntaxKind.IndexedAccessType ? + isGenericTupleType(objectType) && !indexTypeLessThan(indexType, getTotalFixedElementCount(objectType.target)) : + isGenericObjectType(objectType) && !(isTupleType(objectType) && indexTypeLessThan(indexType, getTotalFixedElementCount(objectType.target))) || isGenericReducibleType(objectType)) + ) { + if (objectType.flags & TypeFlags.AnyOrUnknown) { + return objectType; + } + // Defer the operation by creating an indexed access type. + const persistentAccessFlags = accessFlags & AccessFlags.Persistent; + const id = objectType.id + "," + indexType.id + "," + persistentAccessFlags + getAliasId(aliasSymbol, aliasTypeArguments); + let type = indexedAccessTypes.get(id); + if (!type) { + indexedAccessTypes.set(id, type = createIndexedAccessType(objectType, indexType, persistentAccessFlags, aliasSymbol, aliasTypeArguments)); + } + + return type; + } + // In the following we resolve T[K] to the type of the property in T selected by K. + // We treat boolean as different from other unions to improve errors; + // skipping straight to getPropertyTypeForIndexType gives errors with 'boolean' instead of 'true'. + const apparentObjectType = getReducedApparentType(objectType); + if (indexType.flags & TypeFlags.Union && !(indexType.flags & TypeFlags.Boolean)) { + const propTypes: Type[] = []; + let wasMissingProp = false; + for (const t of (indexType as UnionType).types) { + const propType = getPropertyTypeForIndexType(objectType, apparentObjectType, t, indexType, accessNode, accessFlags | (wasMissingProp ? AccessFlags.SuppressNoImplicitAnyError : 0)); + if (propType) { + propTypes.push(propType); + } + else if (!accessNode) { + // If there's no error node, we can immeditely stop, since error reporting is off + return undefined; + } + else { + // Otherwise we set a flag and return at the end of the loop so we still mark all errors + wasMissingProp = true; + } + } + if (wasMissingProp) { + return undefined; + } + return accessFlags & AccessFlags.Writing + ? getIntersectionType(propTypes, IntersectionFlags.None, aliasSymbol, aliasTypeArguments) + : getUnionType(propTypes, UnionReduction.Literal, aliasSymbol, aliasTypeArguments); + } + return getPropertyTypeForIndexType(objectType, apparentObjectType, indexType, indexType, accessNode, accessFlags | AccessFlags.CacheSymbol | AccessFlags.ReportDeprecated); + } + + function getTypeFromIndexedAccessTypeNode(node: IndexedAccessTypeNode) { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const objectType = getTypeFromTypeNode(node.objectType); + const indexType = getTypeFromTypeNode(node.indexType); + const potentialAlias = getAliasSymbolForTypeNode(node); + links.resolvedType = getIndexedAccessType(objectType, indexType, AccessFlags.None, node, potentialAlias, getTypeArgumentsForAliasSymbol(potentialAlias)); + } + return links.resolvedType; + } + + function getTypeFromMappedTypeNode(node: MappedTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const type = createObjectType(ObjectFlags.Mapped, node.symbol) as MappedType; + type.declaration = node; + type.aliasSymbol = getAliasSymbolForTypeNode(node); + type.aliasTypeArguments = getTypeArgumentsForAliasSymbol(type.aliasSymbol); + links.resolvedType = type; + // Eagerly resolve the constraint type which forces an error if the constraint type circularly + // references itself through one or more type aliases. + getConstraintTypeFromMappedType(type); + } + return links.resolvedType; + } + + function getActualTypeVariable(type: Type): Type { + if (type.flags & TypeFlags.Substitution) { + return getActualTypeVariable((type as SubstitutionType).baseType); + } + if ( + type.flags & TypeFlags.IndexedAccess && ( + (type as IndexedAccessType).objectType.flags & TypeFlags.Substitution || + (type as IndexedAccessType).indexType.flags & TypeFlags.Substitution + ) + ) { + return getIndexedAccessType(getActualTypeVariable((type as IndexedAccessType).objectType), getActualTypeVariable((type as IndexedAccessType).indexType)); + } + return type; + } + + function isSimpleTupleType(node: TypeNode): boolean { + return isTupleTypeNode(node) && length(node.elements) > 0 && + !some(node.elements, e => isOptionalTypeNode(e) || isRestTypeNode(e) || isNamedTupleMember(e) && !!(e.questionToken || e.dotDotDotToken)); + } + + function isDeferredType(type: Type, checkTuples: boolean) { + return isGenericType(type) || checkTuples && isTupleType(type) && some(getElementTypes(type), isGenericType); + } + + function getConditionalType(root: ConditionalRoot, mapper: TypeMapper | undefined, forConstraint: boolean, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + let result; + let extraTypes: Type[] | undefined; + let tailCount = 0; + // We loop here for an immediately nested conditional type in the false position, effectively treating + // types of the form 'A extends B ? X : C extends D ? Y : E extends F ? Z : ...' as a single construct for + // purposes of resolution. We also loop here when resolution of a conditional type ends in resolution of + // another (or, through recursion, possibly the same) conditional type. In the potentially tail-recursive + // cases we increment the tail recursion counter and stop after 1000 iterations. + while (true) { + if (tailCount === 1000) { + error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite); + return errorType; + } + const checkType = instantiateType(getActualTypeVariable(root.checkType), mapper); + const extendsType = instantiateType(root.extendsType, mapper); + if (checkType === errorType || extendsType === errorType) { + return errorType; + } + if (checkType === wildcardType || extendsType === wildcardType) { + return wildcardType; + } + const checkTypeNode = skipTypeParentheses(root.node.checkType); + const extendsTypeNode = skipTypeParentheses(root.node.extendsType); + // When the check and extends types are simple tuple types of the same arity, we defer resolution of the + // conditional type when any tuple elements are generic. This is such that non-distributable conditional + // types can be written `[X] extends [Y] ? ...` and be deferred similarly to `X extends Y ? ...`. + const checkTuples = isSimpleTupleType(checkTypeNode) && isSimpleTupleType(extendsTypeNode) && + length((checkTypeNode as TupleTypeNode).elements) === length((extendsTypeNode as TupleTypeNode).elements); + const checkTypeDeferred = isDeferredType(checkType, checkTuples); + let combinedMapper: TypeMapper | undefined; + if (root.inferTypeParameters) { + // When we're looking at making an inference for an infer type, when we get its constraint, it'll automagically be + // instantiated with the context, so it doesn't need the mapper for the inference context - however the constraint + // may refer to another _root_, _uncloned_ `infer` type parameter [1], or to something mapped by `mapper` [2]. + // [1] Eg, if we have `Foo` and `Foo` - `B` is constrained to `T`, which, in turn, has been instantiated + // as `number` + // Conversely, if we have `Foo`, `B` is still constrained to `T` and `T` is instantiated as `A` + // [2] Eg, if we have `Foo` and `Foo` where `Q` is mapped by `mapper` into `number` - `B` is constrained to `T` + // which is in turn instantiated as `Q`, which is in turn instantiated as `number`. + // So we need to: + // * combine `context.nonFixingMapper` with `mapper` so their constraints can be instantiated in the context of `mapper` (otherwise they'd only get inference context information) + // * incorporate all of the component mappers into the combined mapper for the true and false members + // This means we have two mappers that need applying: + // * The original `mapper` used to create this conditional + // * The mapper that maps the infer type parameter to its inference result (`context.mapper`) + const context = createInferenceContext(root.inferTypeParameters, /*signature*/ undefined, InferenceFlags.None); + if (mapper) { + context.nonFixingMapper = combineTypeMappers(context.nonFixingMapper, mapper); + } + if (!checkTypeDeferred) { + // We don't want inferences from constraints as they may cause us to eagerly resolve the + // conditional type instead of deferring resolution. Also, we always want strict function + // types rules (i.e. proper contravariance) for inferences. + inferTypes(context.inferences, checkType, extendsType, InferencePriority.NoConstraints | InferencePriority.AlwaysStrict); + } + // It's possible for 'infer T' type paramteters to be given uninstantiated constraints when the + // those type parameters are used in type references (see getInferredTypeParameterConstraint). For + // that reason we need context.mapper to be first in the combined mapper. See #42636 for examples. + combinedMapper = mapper ? combineTypeMappers(context.mapper, mapper) : context.mapper; + } + // Instantiate the extends type including inferences for 'infer T' type parameters + const inferredExtendsType = combinedMapper ? instantiateType(root.extendsType, combinedMapper) : extendsType; + // We attempt to resolve the conditional type only when the check and extends types are non-generic + if (!checkTypeDeferred && !isDeferredType(inferredExtendsType, checkTuples)) { + // Return falseType for a definitely false extends check. We check an instantiations of the two + // types with type parameters mapped to the wildcard type, the most permissive instantiations + // possible (the wildcard type is assignable to and from all types). If those are not related, + // then no instantiations will be and we can just return the false branch type. + if (!(inferredExtendsType.flags & TypeFlags.AnyOrUnknown) && (checkType.flags & TypeFlags.Any || !isTypeAssignableTo(getPermissiveInstantiation(checkType), getPermissiveInstantiation(inferredExtendsType)))) { + // Return union of trueType and falseType for 'any' since it matches anything. Furthermore, for a + // distributive conditional type applied to the constraint of a type variable, include trueType if + // there are possible values of the check type that are also possible values of the extends type. + // We use a reverse assignability check as it is less expensive than the comparable relationship + // and avoids false positives of a non-empty intersection check. + if (checkType.flags & TypeFlags.Any || forConstraint && !(inferredExtendsType.flags & TypeFlags.Never) && someType(getPermissiveInstantiation(inferredExtendsType), t => isTypeAssignableTo(t, getPermissiveInstantiation(checkType)))) { + (extraTypes || (extraTypes = [])).push(instantiateType(getTypeFromTypeNode(root.node.trueType), combinedMapper || mapper)); + } + // If falseType is an immediately nested conditional type that isn't distributive or has an + // identical checkType, switch to that type and loop. + const falseType = getTypeFromTypeNode(root.node.falseType); + if (falseType.flags & TypeFlags.Conditional) { + const newRoot = (falseType as ConditionalType).root; + if (newRoot.node.parent === root.node && (!newRoot.isDistributive || newRoot.checkType === root.checkType)) { + root = newRoot; + continue; + } + if (canTailRecurse(falseType, mapper)) { + continue; + } + } + result = instantiateType(falseType, mapper); + break; + } + // Return trueType for a definitely true extends check. We check instantiations of the two + // types with type parameters mapped to their restrictive form, i.e. a form of the type parameter + // that has no constraint. This ensures that, for example, the type + // type Foo = T extends { x: string } ? string : number + // doesn't immediately resolve to 'string' instead of being deferred. + if (inferredExtendsType.flags & TypeFlags.AnyOrUnknown || isTypeAssignableTo(getRestrictiveInstantiation(checkType), getRestrictiveInstantiation(inferredExtendsType))) { + const trueType = getTypeFromTypeNode(root.node.trueType); + const trueMapper = combinedMapper || mapper; + if (canTailRecurse(trueType, trueMapper)) { + continue; + } + result = instantiateType(trueType, trueMapper); + break; + } + } + // Return a deferred type for a check that is neither definitely true nor definitely false + result = createType(TypeFlags.Conditional) as ConditionalType; + result.root = root; + result.checkType = instantiateType(root.checkType, mapper); + result.extendsType = instantiateType(root.extendsType, mapper); + result.mapper = mapper; + result.combinedMapper = combinedMapper; + result.aliasSymbol = aliasSymbol || root.aliasSymbol; + result.aliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(root.aliasTypeArguments, mapper!); // TODO: GH#18217 + break; + } + return extraTypes ? getUnionType(append(extraTypes, result)) : result; + // We tail-recurse for generic conditional types that (a) have not already been evaluated and cached, and + // (b) are non distributive, have a check type that is unaffected by instantiation, or have a non-union check + // type. Note that recursion is possible only through aliased conditional types, so we only increment the tail + // recursion counter for those. + function canTailRecurse(newType: Type, newMapper: TypeMapper | undefined) { + if (newType.flags & TypeFlags.Conditional && newMapper) { + const newRoot = (newType as ConditionalType).root; + if (newRoot.outerTypeParameters) { + const typeParamMapper = combineTypeMappers((newType as ConditionalType).mapper, newMapper); + const typeArguments = map(newRoot.outerTypeParameters, t => getMappedType(t, typeParamMapper)); + const newRootMapper = createTypeMapper(newRoot.outerTypeParameters, typeArguments); + const newCheckType = newRoot.isDistributive ? getMappedType(newRoot.checkType, newRootMapper) : undefined; + if (!newCheckType || newCheckType === newRoot.checkType || !(newCheckType.flags & (TypeFlags.Union | TypeFlags.Never))) { + root = newRoot; + mapper = newRootMapper; + aliasSymbol = undefined; + aliasTypeArguments = undefined; + if (newRoot.aliasSymbol) { + tailCount++; + } + return true; + } + } + } + return false; + } + } + + function getTrueTypeFromConditionalType(type: ConditionalType) { + return type.resolvedTrueType || (type.resolvedTrueType = instantiateType(getTypeFromTypeNode(type.root.node.trueType), type.mapper)); + } + + function getFalseTypeFromConditionalType(type: ConditionalType) { + return type.resolvedFalseType || (type.resolvedFalseType = instantiateType(getTypeFromTypeNode(type.root.node.falseType), type.mapper)); + } + + function getInferredTrueTypeFromConditionalType(type: ConditionalType) { + return type.resolvedInferredTrueType || (type.resolvedInferredTrueType = type.combinedMapper ? instantiateType(getTypeFromTypeNode(type.root.node.trueType), type.combinedMapper) : getTrueTypeFromConditionalType(type)); + } + + function getInferTypeParameters(node: ConditionalTypeNode): TypeParameter[] | undefined { + let result: TypeParameter[] | undefined; + if (node.locals) { + node.locals.forEach(symbol => { + if (symbol.flags & SymbolFlags.TypeParameter) { + result = append(result, getDeclaredTypeOfSymbol(symbol)); + } + }); + } + return result; + } + + function isDistributionDependent(root: ConditionalRoot) { + return root.isDistributive && ( + isTypeParameterPossiblyReferenced(root.checkType as TypeParameter, root.node.trueType) || + isTypeParameterPossiblyReferenced(root.checkType as TypeParameter, root.node.falseType) + ); + } + + function getTypeFromConditionalTypeNode(node: ConditionalTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + const checkType = getTypeFromTypeNode(node.checkType); + const aliasSymbol = getAliasSymbolForTypeNode(node); + const aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); + const allOuterTypeParameters = getOuterTypeParameters(node, /*includeThisTypes*/ true); + const outerTypeParameters = aliasTypeArguments ? allOuterTypeParameters : filter(allOuterTypeParameters, tp => isTypeParameterPossiblyReferenced(tp, node)); + const root: ConditionalRoot = { + node, + checkType, + extendsType: getTypeFromTypeNode(node.extendsType), + isDistributive: !!(checkType.flags & TypeFlags.TypeParameter), + inferTypeParameters: getInferTypeParameters(node), + outerTypeParameters, + instantiations: undefined, + aliasSymbol, + aliasTypeArguments, + }; + links.resolvedType = getConditionalType(root, /*mapper*/ undefined, /*forConstraint*/ false); + if (outerTypeParameters) { + root.instantiations = new Map(); + root.instantiations.set(getTypeListId(outerTypeParameters), links.resolvedType); + } + } + return links.resolvedType; + } + + function getTypeFromInferTypeNode(node: InferTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getDeclaredTypeOfTypeParameter(getSymbolOfDeclaration(node.typeParameter)); + } + return links.resolvedType; + } + + function getIdentifierChain(node: EntityName): Identifier[] { + if (isIdentifier(node)) { + return [node]; + } + else { + return append(getIdentifierChain(node.left), node.right); + } + } + + function getTypeFromImportTypeNode(node: ImportTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + if (!isLiteralImportTypeNode(node)) { + error(node.argument, Diagnostics.String_literal_expected); + links.resolvedSymbol = unknownSymbol; + return links.resolvedType = errorType; + } + const targetMeaning = node.isTypeOf ? SymbolFlags.Value : node.flags & NodeFlags.JSDoc ? SymbolFlags.Value | SymbolFlags.Type : SymbolFlags.Type; + // TODO: Future work: support unions/generics/whatever via a deferred import-type + const innerModuleSymbol = resolveExternalModuleName(node, node.argument.literal); + if (!innerModuleSymbol) { + links.resolvedSymbol = unknownSymbol; + return links.resolvedType = errorType; + } + const isExportEquals = !!innerModuleSymbol.exports?.get(InternalSymbolName.ExportEquals); + const moduleSymbol = resolveExternalModuleSymbol(innerModuleSymbol, /*dontResolveAlias*/ false); + if (!nodeIsMissing(node.qualifier)) { + const nameStack: Identifier[] = getIdentifierChain(node.qualifier!); + let currentNamespace = moduleSymbol; + let current: Identifier | undefined; + while (current = nameStack.shift()) { + const meaning = nameStack.length ? SymbolFlags.Namespace : targetMeaning; + // typeof a.b.c is normally resolved using `checkExpression` which in turn defers to `checkQualifiedName` + // That, in turn, ultimately uses `getPropertyOfType` on the type of the symbol, which differs slightly from + // the `exports` lookup process that only looks up namespace members which is used for most type references + const mergedResolvedSymbol = getMergedSymbol(resolveSymbol(currentNamespace)); + const symbolFromVariable = node.isTypeOf || isInJSFile(node) && isExportEquals + ? getPropertyOfType(getTypeOfSymbol(mergedResolvedSymbol), current.escapedText, /*skipObjectFunctionPropertyAugment*/ false, /*includeTypeOnlyMembers*/ true) + : undefined; + const symbolFromModule = node.isTypeOf ? undefined : getSymbol(getExportsOfSymbol(mergedResolvedSymbol), current.escapedText, meaning); + const next = symbolFromModule ?? symbolFromVariable; + if (!next) { + error(current, Diagnostics.Namespace_0_has_no_exported_member_1, getFullyQualifiedName(currentNamespace), declarationNameToString(current)); + return links.resolvedType = errorType; + } + getNodeLinks(current).resolvedSymbol = next; + getNodeLinks(current.parent).resolvedSymbol = next; + currentNamespace = next; + } + links.resolvedType = resolveImportSymbolType(node, links, currentNamespace, targetMeaning); + } + else { + if (moduleSymbol.flags & targetMeaning) { + links.resolvedType = resolveImportSymbolType(node, links, moduleSymbol, targetMeaning); + } + else { + const errorMessage = targetMeaning === SymbolFlags.Value + ? Diagnostics.Module_0_does_not_refer_to_a_value_but_is_used_as_a_value_here + : Diagnostics.Module_0_does_not_refer_to_a_type_but_is_used_as_a_type_here_Did_you_mean_typeof_import_0; + + error(node, errorMessage, node.argument.literal.text); + + links.resolvedSymbol = unknownSymbol; + links.resolvedType = errorType; + } + } + } + return links.resolvedType; + } + + function resolveImportSymbolType(node: ImportTypeNode, links: NodeLinks, symbol: Symbol, meaning: SymbolFlags) { + const resolvedSymbol = resolveSymbol(symbol); + links.resolvedSymbol = resolvedSymbol; + if (meaning === SymbolFlags.Value) { + return getInstantiationExpressionType(getTypeOfSymbol(symbol), node); // intentionally doesn't use resolved symbol so type is cached as expected on the alias + } + else { + return getTypeReferenceType(node, resolvedSymbol); // getTypeReferenceType doesn't handle aliases - it must get the resolved symbol + } + } + + function getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node: TypeLiteralNode | FunctionOrConstructorTypeNode | JSDocTypeLiteral | JSDocFunctionType | JSDocSignature): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + // Deferred resolution of members is handled by resolveObjectTypeMembers + const aliasSymbol = getAliasSymbolForTypeNode(node); + if (getMembersOfSymbol(node.symbol).size === 0 && !aliasSymbol) { + links.resolvedType = emptyTypeLiteralType; + } + else { + let type = createObjectType(ObjectFlags.Anonymous, node.symbol); + type.aliasSymbol = aliasSymbol; + type.aliasTypeArguments = getTypeArgumentsForAliasSymbol(aliasSymbol); + if (isJSDocTypeLiteral(node) && node.isArrayType) { + type = createArrayType(type); + } + links.resolvedType = type; + } + } + return links.resolvedType; + } + + function getAliasSymbolForTypeNode(node: Node) { + let host = node.parent; + while (isParenthesizedTypeNode(host) || isJSDocTypeExpression(host) || isTypeOperatorNode(host) && host.operator === SyntaxKind.ReadonlyKeyword) { + host = host.parent; + } + return isTypeAlias(host) ? getSymbolOfDeclaration(host) : undefined; + } + + function getTypeArgumentsForAliasSymbol(symbol: Symbol | undefined) { + return symbol ? getLocalTypeParametersOfClassOrInterfaceOrTypeAlias(symbol) : undefined; + } + + function isNonGenericObjectType(type: Type) { + return !!(type.flags & TypeFlags.Object) && !isGenericMappedType(type); + } + + function isEmptyObjectTypeOrSpreadsIntoEmptyObject(type: Type) { + return isEmptyObjectType(type) || !!(type.flags & (TypeFlags.Null | TypeFlags.Undefined | TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)); + } + + function tryMergeUnionOfObjectTypeAndEmptyObject(type: Type, readonly: boolean): Type { + if (!(type.flags & TypeFlags.Union)) { + return type; + } + if (every((type as UnionType).types, isEmptyObjectTypeOrSpreadsIntoEmptyObject)) { + return find((type as UnionType).types, isEmptyObjectType) || emptyObjectType; + } + const firstType = find((type as UnionType).types, t => !isEmptyObjectTypeOrSpreadsIntoEmptyObject(t)); + if (!firstType) { + return type; + } + const secondType = find((type as UnionType).types, t => t !== firstType && !isEmptyObjectTypeOrSpreadsIntoEmptyObject(t)); + if (secondType) { + return type; + } + return getAnonymousPartialType(firstType); + + function getAnonymousPartialType(type: Type) { + // gets the type as if it had been spread, but where everything in the spread is made optional + const members = createSymbolTable(); + for (const prop of getPropertiesOfType(type)) { + if (getDeclarationModifierFlagsFromSymbol(prop) & (ModifierFlags.Private | ModifierFlags.Protected)) { + // do nothing, skip privates + } + else if (isSpreadableProperty(prop)) { + const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); + const flags = SymbolFlags.Property | SymbolFlags.Optional; + const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0)); + result.links.type = isSetonlyAccessor ? undefinedType : addOptionality(getTypeOfSymbol(prop), /*isProperty*/ true); + result.declarations = prop.declarations; + result.links.nameType = getSymbolLinks(prop).nameType; + result.links.syntheticOrigin = prop; + members.set(prop.escapedName, result); + } + } + const spread = createAnonymousType(type.symbol, members, emptyArray, emptyArray, getIndexInfosOfType(type)); + spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral; + return spread; + } + } + + /** + * Since the source of spread types are object literals, which are not binary, + * this function should be called in a left folding style, with left = previous result of getSpreadType + * and right = the new element to be spread. + */ + function getSpreadType(left: Type, right: Type, symbol: Symbol | undefined, objectFlags: ObjectFlags, readonly: boolean): Type { + if (left.flags & TypeFlags.Any || right.flags & TypeFlags.Any) { + return anyType; + } + if (left.flags & TypeFlags.Unknown || right.flags & TypeFlags.Unknown) { + return unknownType; + } + if (left.flags & TypeFlags.Never) { + return right; + } + if (right.flags & TypeFlags.Never) { + return left; + } + left = tryMergeUnionOfObjectTypeAndEmptyObject(left, readonly); + if (left.flags & TypeFlags.Union) { + return checkCrossProductUnion([left, right]) + ? mapType(left, t => getSpreadType(t, right, symbol, objectFlags, readonly)) + : errorType; + } + right = tryMergeUnionOfObjectTypeAndEmptyObject(right, readonly); + if (right.flags & TypeFlags.Union) { + return checkCrossProductUnion([left, right]) + ? mapType(right, t => getSpreadType(left, t, symbol, objectFlags, readonly)) + : errorType; + } + if (right.flags & (TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)) { + return left; + } + + if (isGenericObjectType(left) || isGenericObjectType(right)) { + if (isEmptyObjectType(left)) { + return right; + } + // When the left type is an intersection, we may need to merge the last constituent of the + // intersection with the right type. For example when the left type is 'T & { a: string }' + // and the right type is '{ b: string }' we produce 'T & { a: string, b: string }'. + if (left.flags & TypeFlags.Intersection) { + const types = (left as IntersectionType).types; + const lastLeft = types[types.length - 1]; + if (isNonGenericObjectType(lastLeft) && isNonGenericObjectType(right)) { + return getIntersectionType(concatenate(types.slice(0, types.length - 1), [getSpreadType(lastLeft, right, symbol, objectFlags, readonly)])); + } + } + return getIntersectionType([left, right]); + } + + const members = createSymbolTable(); + const skippedPrivateMembers = new Set<__String>(); + const indexInfos = left === emptyObjectType ? getIndexInfosOfType(right) : getUnionIndexInfos([left, right]); + + for (const rightProp of getPropertiesOfType(right)) { + if (getDeclarationModifierFlagsFromSymbol(rightProp) & (ModifierFlags.Private | ModifierFlags.Protected)) { + skippedPrivateMembers.add(rightProp.escapedName); + } + else if (isSpreadableProperty(rightProp)) { + members.set(rightProp.escapedName, getSpreadSymbol(rightProp, readonly)); + } + } + + for (const leftProp of getPropertiesOfType(left)) { + if (skippedPrivateMembers.has(leftProp.escapedName) || !isSpreadableProperty(leftProp)) { + continue; + } + if (members.has(leftProp.escapedName)) { + const rightProp = members.get(leftProp.escapedName)!; + const rightType = getTypeOfSymbol(rightProp); + if (rightProp.flags & SymbolFlags.Optional) { + const declarations = concatenate(leftProp.declarations, rightProp.declarations); + const flags = SymbolFlags.Property | (leftProp.flags & SymbolFlags.Optional); + const result = createSymbol(flags, leftProp.escapedName); + // Optimization: avoid calculating the union type if spreading into the exact same type. + // This is common, e.g. spreading one options bag into another where the bags have the + // same type, or have properties which overlap. If the unions are large, it may turn out + // to be expensive to perform subtype reduction. + const leftType = getTypeOfSymbol(leftProp); + const leftTypeWithoutUndefined = removeMissingOrUndefinedType(leftType); + const rightTypeWithoutUndefined = removeMissingOrUndefinedType(rightType); + result.links.type = leftTypeWithoutUndefined === rightTypeWithoutUndefined ? leftType : getUnionType([leftType, rightTypeWithoutUndefined], UnionReduction.Subtype); + result.links.leftSpread = leftProp; + result.links.rightSpread = rightProp; + result.declarations = declarations; + result.links.nameType = getSymbolLinks(leftProp).nameType; + members.set(leftProp.escapedName, result); + } + } + else { + members.set(leftProp.escapedName, getSpreadSymbol(leftProp, readonly)); + } + } + + const spread = createAnonymousType(symbol, members, emptyArray, emptyArray, sameMap(indexInfos, info => getIndexInfoWithReadonly(info, readonly))); + spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral | ObjectFlags.ContainsSpread | objectFlags; + return spread; + } + + /** We approximate own properties as non-methods plus methods that are inside the object literal */ + function isSpreadableProperty(prop: Symbol): boolean { + return !some(prop.declarations, isPrivateIdentifierClassElementDeclaration) && + (!(prop.flags & (SymbolFlags.Method | SymbolFlags.GetAccessor | SymbolFlags.SetAccessor)) || + !prop.declarations?.some(decl => isClassLike(decl.parent))); + } + + function getSpreadSymbol(prop: Symbol, readonly: boolean) { + const isSetonlyAccessor = prop.flags & SymbolFlags.SetAccessor && !(prop.flags & SymbolFlags.GetAccessor); + if (!isSetonlyAccessor && readonly === isReadonlySymbol(prop)) { + return prop; + } + const flags = SymbolFlags.Property | (prop.flags & SymbolFlags.Optional); + const result = createSymbol(flags, prop.escapedName, getIsLateCheckFlag(prop) | (readonly ? CheckFlags.Readonly : 0)); + result.links.type = isSetonlyAccessor ? undefinedType : getTypeOfSymbol(prop); + result.declarations = prop.declarations; + result.links.nameType = getSymbolLinks(prop).nameType; + result.links.syntheticOrigin = prop; + return result; + } + + function getIndexInfoWithReadonly(info: IndexInfo, readonly: boolean) { + return info.isReadonly !== readonly ? createIndexInfo(info.keyType, info.type, readonly, info.declaration) : info; + } + + function createLiteralType(flags: TypeFlags, value: string | number | PseudoBigInt, symbol?: Symbol, regularType?: LiteralType) { + const type = createTypeWithSymbol(flags, symbol!) as LiteralType; + type.value = value; + type.regularType = regularType || type; + return type; + } + + function getFreshTypeOfLiteralType(type: Type): Type { + if (type.flags & TypeFlags.Freshable) { + if (!(type as FreshableType).freshType) { + const freshType = createLiteralType(type.flags, (type as LiteralType).value, (type as LiteralType).symbol, type as LiteralType); + freshType.freshType = freshType; + (type as FreshableType).freshType = freshType; + } + return (type as FreshableType).freshType; + } + return type; + } + + function getRegularTypeOfLiteralType(type: Type): Type { + return type.flags & TypeFlags.Freshable ? (type as FreshableType).regularType : + type.flags & TypeFlags.Union ? ((type as UnionType).regularType || ((type as UnionType).regularType = mapType(type, getRegularTypeOfLiteralType) as UnionType)) : + type; + } + + function isFreshLiteralType(type: Type) { + return !!(type.flags & TypeFlags.Freshable) && (type as LiteralType).freshType === type; + } + + function getStringLiteralType(value: string): StringLiteralType { + let type; + return stringLiteralTypes.get(value) || + (stringLiteralTypes.set(value, type = createLiteralType(TypeFlags.StringLiteral, value) as StringLiteralType), type); + } + + function getNumberLiteralType(value: number): NumberLiteralType { + let type; + return numberLiteralTypes.get(value) || + (numberLiteralTypes.set(value, type = createLiteralType(TypeFlags.NumberLiteral, value) as NumberLiteralType), type); + } + + function getBigIntLiteralType(value: PseudoBigInt): BigIntLiteralType { + let type; + const key = pseudoBigIntToString(value); + return bigIntLiteralTypes.get(key) || + (bigIntLiteralTypes.set(key, type = createLiteralType(TypeFlags.BigIntLiteral, value) as BigIntLiteralType), type); + } + + function getEnumLiteralType(value: string | number, enumId: number, symbol: Symbol): LiteralType { + let type; + const key = `${enumId}${typeof value === "string" ? "@" : "#"}${value}`; + const flags = TypeFlags.EnumLiteral | (typeof value === "string" ? TypeFlags.StringLiteral : TypeFlags.NumberLiteral); + return enumLiteralTypes.get(key) || + (enumLiteralTypes.set(key, type = createLiteralType(flags, value, symbol)), type); + } + + function getTypeFromLiteralTypeNode(node: LiteralTypeNode): Type { + if (node.literal.kind === SyntaxKind.NullKeyword) { + return nullType; + } + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getRegularTypeOfLiteralType(checkExpression(node.literal)); + } + return links.resolvedType; + } + + function createUniqueESSymbolType(symbol: Symbol) { + const type = createTypeWithSymbol(TypeFlags.UniqueESSymbol, symbol) as UniqueESSymbolType; + type.escapedName = `__@${type.symbol.escapedName}@${getSymbolId(type.symbol)}` as __String; + return type; + } + + function getESSymbolLikeTypeForNode(node: Node) { + if (isInJSFile(node) && isJSDocTypeExpression(node)) { + const host = getJSDocHost(node); + if (host) { + node = getSingleVariableOfVariableStatement(host) || host; + } + } + if (isValidESSymbolDeclaration(node)) { + const symbol = isCommonJsExportPropertyAssignment(node) ? getSymbolOfNode((node as BinaryExpression).left) : getSymbolOfNode(node); + if (symbol) { + const links = getSymbolLinks(symbol); + return links.uniqueESSymbolType || (links.uniqueESSymbolType = createUniqueESSymbolType(symbol)); + } + } + return esSymbolType; + } + + function getThisType(node: Node): Type { + const container = getThisContainer(node, /*includeArrowFunctions*/ false, /*includeClassComputedPropertyName*/ false); + const parent = container && container.parent; + if (parent && (isClassLike(parent) || parent.kind === SyntaxKind.InterfaceDeclaration)) { + if ( + !isStatic(container) && + (!isConstructorDeclaration(container) || isNodeDescendantOf(node, container.body)) + ) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(parent as ClassLikeDeclaration | InterfaceDeclaration)).thisType!; + } + } + + // inside x.prototype = { ... } + if (parent && isObjectLiteralExpression(parent) && isBinaryExpression(parent.parent) && getAssignmentDeclarationKind(parent.parent) === AssignmentDeclarationKind.Prototype) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfNode(parent.parent.left)!.parent!).thisType!; + } + // /** @return {this} */ + // x.prototype.m = function() { ... } + const host = node.flags & NodeFlags.JSDoc ? getHostSignatureFromJSDoc(node) : undefined; + if (host && isFunctionExpression(host) && isBinaryExpression(host.parent) && getAssignmentDeclarationKind(host.parent) === AssignmentDeclarationKind.PrototypeProperty) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfNode(host.parent.left)!.parent!).thisType!; + } + // inside constructor function C() { ... } + if (isJSConstructor(container) && isNodeDescendantOf(node, container.body)) { + return getDeclaredTypeOfClassOrInterface(getSymbolOfDeclaration(container)).thisType!; + } + error(node, Diagnostics.A_this_type_is_available_only_in_a_non_static_member_of_a_class_or_interface); + return errorType; + } + + function getTypeFromThisTypeNode(node: ThisExpression | ThisTypeNode): Type { + const links = getNodeLinks(node); + if (!links.resolvedType) { + links.resolvedType = getThisType(node); + } + return links.resolvedType; + } + + function getTypeFromRestTypeNode(node: RestTypeNode | NamedTupleMember) { + return getTypeFromTypeNode(getArrayElementTypeNode(node.type) || node.type); + } + + function getArrayElementTypeNode(node: TypeNode): TypeNode | undefined { + switch (node.kind) { + case SyntaxKind.ParenthesizedType: + return getArrayElementTypeNode((node as ParenthesizedTypeNode).type); + case SyntaxKind.TupleType: + if ((node as TupleTypeNode).elements.length === 1) { + node = (node as TupleTypeNode).elements[0]; + if (node.kind === SyntaxKind.RestType || node.kind === SyntaxKind.NamedTupleMember && (node as NamedTupleMember).dotDotDotToken) { + return getArrayElementTypeNode((node as RestTypeNode | NamedTupleMember).type); + } + } + break; + case SyntaxKind.ArrayType: + return (node as ArrayTypeNode).elementType; + } + return undefined; + } + + function getTypeFromNamedTupleTypeNode(node: NamedTupleMember): Type { + const links = getNodeLinks(node); + return links.resolvedType || (links.resolvedType = node.dotDotDotToken ? getTypeFromRestTypeNode(node) : + addOptionality(getTypeFromTypeNode(node.type), /*isProperty*/ true, !!node.questionToken)); + } + + function getTypeFromTypeNode(node: TypeNode): Type { + return getConditionalFlowTypeOfType(getTypeFromTypeNodeWorker(node), node); + } + + function getTypeFromTypeNodeWorker(node: TypeNode): Type { + switch (node.kind) { + case SyntaxKind.AnyKeyword: + case SyntaxKind.JSDocAllType: + case SyntaxKind.JSDocUnknownType: + return anyType; + case SyntaxKind.UnknownKeyword: + return unknownType; + case SyntaxKind.StringKeyword: + return stringType; + case SyntaxKind.NumberKeyword: + return numberType; + case SyntaxKind.BigIntKeyword: + return bigintType; + case SyntaxKind.BooleanKeyword: + return booleanType; + case SyntaxKind.SymbolKeyword: + return esSymbolType; + case SyntaxKind.VoidKeyword: + return voidType; + case SyntaxKind.UndefinedKeyword: + return undefinedType; + case SyntaxKind.NullKeyword as TypeNodeSyntaxKind: + // TODO(rbuckton): `NullKeyword` is no longer a `TypeNode`, but we defensively allow it here because of incorrect casts in the Language Service. + return nullType; + case SyntaxKind.NeverKeyword: + return neverType; + case SyntaxKind.ObjectKeyword: + return node.flags & NodeFlags.JavaScriptFile && !noImplicitAny ? anyType : nonPrimitiveType; + case SyntaxKind.IntrinsicKeyword: + return intrinsicMarkerType; + case SyntaxKind.ThisType: + case SyntaxKind.ThisKeyword as TypeNodeSyntaxKind: + // TODO(rbuckton): `ThisKeyword` is no longer a `TypeNode`, but we defensively allow it here because of incorrect casts in the Language Service and because of `isPartOfTypeNode`. + return getTypeFromThisTypeNode(node as ThisExpression | ThisTypeNode); + case SyntaxKind.LiteralType: + return getTypeFromLiteralTypeNode(node as LiteralTypeNode); + case SyntaxKind.TypeReference: + return getTypeFromTypeReference(node as TypeReferenceNode); + case SyntaxKind.TypePredicate: + return (node as TypePredicateNode).assertsModifier ? voidType : booleanType; + case SyntaxKind.ExpressionWithTypeArguments: + return getTypeFromTypeReference(node as ExpressionWithTypeArguments); + case SyntaxKind.TypeQuery: + return getTypeFromTypeQueryNode(node as TypeQueryNode); + case SyntaxKind.ArrayType: + case SyntaxKind.TupleType: + return getTypeFromArrayOrTupleTypeNode(node as ArrayTypeNode | TupleTypeNode); + case SyntaxKind.OptionalType: + return getTypeFromOptionalTypeNode(node as OptionalTypeNode); + case SyntaxKind.UnionType: + return getTypeFromUnionTypeNode(node as UnionTypeNode); + case SyntaxKind.IntersectionType: + return getTypeFromIntersectionTypeNode(node as IntersectionTypeNode); + case SyntaxKind.JSDocNullableType: + return getTypeFromJSDocNullableTypeNode(node as JSDocNullableType); + case SyntaxKind.JSDocOptionalType: + return addOptionality(getTypeFromTypeNode((node as JSDocOptionalType).type)); + case SyntaxKind.NamedTupleMember: + return getTypeFromNamedTupleTypeNode(node as NamedTupleMember); + case SyntaxKind.ParenthesizedType: + case SyntaxKind.JSDocNonNullableType: + case SyntaxKind.JSDocTypeExpression: + return getTypeFromTypeNode((node as ParenthesizedTypeNode | JSDocTypeReferencingNode | JSDocTypeExpression | NamedTupleMember).type); + case SyntaxKind.RestType: + return getTypeFromRestTypeNode(node as RestTypeNode); + case SyntaxKind.JSDocVariadicType: + return getTypeFromJSDocVariadicType(node as JSDocVariadicType); + case SyntaxKind.FunctionType: + case SyntaxKind.ConstructorType: + case SyntaxKind.TypeLiteral: + case SyntaxKind.JSDocTypeLiteral: + case SyntaxKind.JSDocFunctionType: + case SyntaxKind.JSDocSignature: + return getTypeFromTypeLiteralOrFunctionOrConstructorTypeNode(node as TypeLiteralNode | FunctionOrConstructorTypeNode | JSDocTypeLiteral | JSDocFunctionType | JSDocSignature); + case SyntaxKind.TypeOperator: + return getTypeFromTypeOperatorNode(node as TypeOperatorNode); + case SyntaxKind.IndexedAccessType: + return getTypeFromIndexedAccessTypeNode(node as IndexedAccessTypeNode); + case SyntaxKind.MappedType: + return getTypeFromMappedTypeNode(node as MappedTypeNode); + case SyntaxKind.ConditionalType: + return getTypeFromConditionalTypeNode(node as ConditionalTypeNode); + case SyntaxKind.InferType: + return getTypeFromInferTypeNode(node as InferTypeNode); + case SyntaxKind.TemplateLiteralType: + return getTypeFromTemplateTypeNode(node as TemplateLiteralTypeNode); + case SyntaxKind.ImportType: + return getTypeFromImportTypeNode(node as ImportTypeNode); + // This function assumes that an identifier, qualified name, or property access expression is a type expression + // Callers should first ensure this by calling `isPartOfTypeNode` + // TODO(rbuckton): These aren't valid TypeNodes, but we treat them as such because of `isPartOfTypeNode`, which returns `true` for things that aren't `TypeNode`s. + case SyntaxKind.Identifier as TypeNodeSyntaxKind: + case SyntaxKind.QualifiedName as TypeNodeSyntaxKind: + case SyntaxKind.PropertyAccessExpression as TypeNodeSyntaxKind: + const symbol = getSymbolAtLocation(node); + return symbol ? getDeclaredTypeOfSymbol(symbol) : errorType; + default: + return errorType; + } + } + + function instantiateList(items: readonly T[], mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[]; + function instantiateList(items: readonly T[] | undefined, mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[] | undefined; + function instantiateList(items: readonly T[] | undefined, mapper: TypeMapper, instantiator: (item: T, mapper: TypeMapper) => T): readonly T[] | undefined { + if (items && items.length) { + for (let i = 0; i < items.length; i++) { + const item = items[i]; + const mapped = instantiator(item, mapper); + if (item !== mapped) { + const result = i === 0 ? [] : items.slice(0, i); + result.push(mapped); + for (i++; i < items.length; i++) { + result.push(instantiator(items[i], mapper)); + } + return result; + } + } + } + return items; + } + + function instantiateTypes(types: readonly Type[], mapper: TypeMapper): readonly Type[]; + function instantiateTypes(types: readonly Type[] | undefined, mapper: TypeMapper): readonly Type[] | undefined; + function instantiateTypes(types: readonly Type[] | undefined, mapper: TypeMapper): readonly Type[] | undefined { + return instantiateList(types, mapper, instantiateType); + } + + function instantiateSignatures(signatures: readonly Signature[], mapper: TypeMapper): readonly Signature[] { + return instantiateList(signatures, mapper, instantiateSignature); + } + + function instantiateIndexInfos(indexInfos: readonly IndexInfo[], mapper: TypeMapper): readonly IndexInfo[] { + return instantiateList(indexInfos, mapper, instantiateIndexInfo); + } + + function createTypeMapper(sources: readonly TypeParameter[], targets: readonly Type[] | undefined): TypeMapper { + return sources.length === 1 ? makeUnaryTypeMapper(sources[0], targets ? targets[0] : anyType) : makeArrayTypeMapper(sources, targets); + } + + function getMappedType(type: Type, mapper: TypeMapper): Type { + switch (mapper.kind) { + case TypeMapKind.Simple: + return type === mapper.source ? mapper.target : type; + case TypeMapKind.Array: { + const sources = mapper.sources; + const targets = mapper.targets; + for (let i = 0; i < sources.length; i++) { + if (type === sources[i]) { + return targets ? targets[i] : anyType; + } + } + return type; + } + case TypeMapKind.Deferred: { + const sources = mapper.sources; + const targets = mapper.targets; + for (let i = 0; i < sources.length; i++) { + if (type === sources[i]) { + return targets[i](); + } + } + return type; + } + case TypeMapKind.Function: + return mapper.func(type); + case TypeMapKind.Composite: + case TypeMapKind.Merged: + const t1 = getMappedType(type, mapper.mapper1); + return t1 !== type && mapper.kind === TypeMapKind.Composite ? instantiateType(t1, mapper.mapper2) : getMappedType(t1, mapper.mapper2); + } + } + + function makeUnaryTypeMapper(source: Type, target: Type): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Simple, source, target }); + } + + function makeArrayTypeMapper(sources: readonly TypeParameter[], targets: readonly Type[] | undefined): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Array, sources, targets }); + } + + function makeFunctionTypeMapper(func: (t: Type) => Type, debugInfo: () => string): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Function, func, debugInfo: Debug.isDebugging ? debugInfo : undefined }); + } + + function makeDeferredTypeMapper(sources: readonly TypeParameter[], targets: (() => Type)[]) { + return Debug.attachDebugPrototypeIfDebug({ kind: TypeMapKind.Deferred, sources, targets }); + } + + function makeCompositeTypeMapper(kind: TypeMapKind.Composite | TypeMapKind.Merged, mapper1: TypeMapper, mapper2: TypeMapper): TypeMapper { + return Debug.attachDebugPrototypeIfDebug({ kind, mapper1, mapper2 }); + } + + function createTypeEraser(sources: readonly TypeParameter[]): TypeMapper { + return createTypeMapper(sources, /*targets*/ undefined); + } + + /** + * Maps forward-references to later types parameters to the empty object type. + * This is used during inference when instantiating type parameter defaults. + */ + function createBackreferenceMapper(context: InferenceContext, index: number): TypeMapper { + const forwardInferences = context.inferences.slice(index); + return createTypeMapper(map(forwardInferences, i => i.typeParameter), map(forwardInferences, () => unknownType)); + } + + function combineTypeMappers(mapper1: TypeMapper | undefined, mapper2: TypeMapper): TypeMapper { + return mapper1 ? makeCompositeTypeMapper(TypeMapKind.Composite, mapper1, mapper2) : mapper2; + } + + function mergeTypeMappers(mapper1: TypeMapper | undefined, mapper2: TypeMapper): TypeMapper { + return mapper1 ? makeCompositeTypeMapper(TypeMapKind.Merged, mapper1, mapper2) : mapper2; + } + + function prependTypeMapping(source: Type, target: Type, mapper: TypeMapper | undefined) { + return !mapper ? makeUnaryTypeMapper(source, target) : makeCompositeTypeMapper(TypeMapKind.Merged, makeUnaryTypeMapper(source, target), mapper); + } + + function appendTypeMapping(mapper: TypeMapper | undefined, source: Type, target: Type) { + return !mapper ? makeUnaryTypeMapper(source, target) : makeCompositeTypeMapper(TypeMapKind.Merged, mapper, makeUnaryTypeMapper(source, target)); + } + + function getRestrictiveTypeParameter(tp: TypeParameter) { + return !tp.constraint && !getConstraintDeclaration(tp) || tp.constraint === noConstraintType ? tp : tp.restrictiveInstantiation || ( + tp.restrictiveInstantiation = createTypeParameter(tp.symbol), (tp.restrictiveInstantiation as TypeParameter).constraint = noConstraintType, tp.restrictiveInstantiation + ); + } + + function cloneTypeParameter(typeParameter: TypeParameter): TypeParameter { + const result = createTypeParameter(typeParameter.symbol); + result.target = typeParameter; + return result; + } + + function instantiateTypePredicate(predicate: TypePredicate, mapper: TypeMapper): TypePredicate { + return createTypePredicate(predicate.kind, predicate.parameterName, predicate.parameterIndex, instantiateType(predicate.type, mapper)); + } + + function instantiateSignature(signature: Signature, mapper: TypeMapper, eraseTypeParameters?: boolean): Signature { + let freshTypeParameters: TypeParameter[] | undefined; + if (signature.typeParameters && !eraseTypeParameters) { + // First create a fresh set of type parameters, then include a mapping from the old to the + // new type parameters in the mapper function. Finally store this mapper in the new type + // parameters such that we can use it when instantiating constraints. + freshTypeParameters = map(signature.typeParameters, cloneTypeParameter); + mapper = combineTypeMappers(createTypeMapper(signature.typeParameters, freshTypeParameters), mapper); + for (const tp of freshTypeParameters) { + tp.mapper = mapper; + } + } + // Don't compute resolvedReturnType and resolvedTypePredicate now, + // because using `mapper` now could trigger inferences to become fixed. (See `createInferenceContext`.) + // See GH#17600. + const result = createSignature(signature.declaration, freshTypeParameters, signature.thisParameter && instantiateSymbol(signature.thisParameter, mapper), instantiateList(signature.parameters, mapper, instantiateSymbol), /*resolvedReturnType*/ undefined, /*resolvedTypePredicate*/ undefined, signature.minArgumentCount, signature.flags & SignatureFlags.PropagatingFlags); + result.target = signature; + result.mapper = mapper; + return result; + } + + function instantiateSymbol(symbol: Symbol, mapper: TypeMapper): Symbol { + const links = getSymbolLinks(symbol); + // If the type of the symbol is already resolved, and if that type could not possibly + // be affected by instantiation, simply return the symbol itself. + if (links.type && !couldContainTypeVariables(links.type)) { + if (!(symbol.flags & SymbolFlags.SetAccessor)) { + return symbol; + } + // If we're a setter, check writeType. + if (links.writeType && !couldContainTypeVariables(links.writeType)) { + return symbol; + } + } + if (getCheckFlags(symbol) & CheckFlags.Instantiated) { + // If symbol being instantiated is itself a instantiation, fetch the original target and combine the + // type mappers. This ensures that original type identities are properly preserved and that aliases + // always reference a non-aliases. + symbol = links.target!; + mapper = combineTypeMappers(links.mapper, mapper); + } + // Keep the flags from the symbol we're instantiating. Mark that is instantiated, and + // also transient so that we can just store data on it directly. + const result = createSymbol(symbol.flags, symbol.escapedName, CheckFlags.Instantiated | getCheckFlags(symbol) & (CheckFlags.Readonly | CheckFlags.Late | CheckFlags.OptionalParameter | CheckFlags.RestParameter)); + result.declarations = symbol.declarations; + result.parent = symbol.parent; + result.links.target = symbol; + result.links.mapper = mapper; + if (symbol.valueDeclaration) { + result.valueDeclaration = symbol.valueDeclaration; + } + if (links.nameType) { + result.links.nameType = links.nameType; + } + return result; + } + + function getObjectTypeInstantiation(type: AnonymousType | DeferredTypeReference, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]) { + const declaration = type.objectFlags & ObjectFlags.Reference ? (type as TypeReference).node! : + type.objectFlags & ObjectFlags.InstantiationExpressionType ? (type as InstantiationExpressionType).node : + type.symbol.declarations![0]; + const links = getNodeLinks(declaration); + const target = type.objectFlags & ObjectFlags.Reference ? links.resolvedType! as DeferredTypeReference : + type.objectFlags & ObjectFlags.Instantiated ? type.target! : type; + let typeParameters = type.objectFlags & ObjectFlags.SingleSignatureType ? (type as SingleSignatureType).outerTypeParameters : links.outerTypeParameters; + if (!typeParameters) { + // The first time an anonymous type is instantiated we compute and store a list of the type + // parameters that are in scope (and therefore potentially referenced). For type literals that + // aren't the right hand side of a generic type alias declaration we optimize by reducing the + // set of type parameters to those that are possibly referenced in the literal. + let outerTypeParameters = getOuterTypeParameters(declaration, /*includeThisTypes*/ true); + if (isJSConstructor(declaration)) { + const templateTagParameters = getTypeParametersFromDeclaration(declaration as DeclarationWithTypeParameters); + outerTypeParameters = addRange(outerTypeParameters, templateTagParameters); + } + typeParameters = outerTypeParameters || emptyArray; + const allDeclarations = type.objectFlags & (ObjectFlags.Reference | ObjectFlags.InstantiationExpressionType) ? [declaration] : type.symbol.declarations!; + typeParameters = (target.objectFlags & (ObjectFlags.Reference | ObjectFlags.InstantiationExpressionType) || target.symbol.flags & SymbolFlags.Method || target.symbol.flags & SymbolFlags.TypeLiteral) && !target.aliasTypeArguments ? + filter(typeParameters, tp => some(allDeclarations, d => isTypeParameterPossiblyReferenced(tp, d))) : + typeParameters; + links.outerTypeParameters = typeParameters; + } + if (typeParameters.length) { + // We are instantiating an anonymous type that has one or more type parameters in scope. Apply the + // mapper to the type parameters to produce the effective list of type arguments, and compute the + // instantiation cache key from the type IDs of the type arguments. + const combinedMapper = combineTypeMappers(type.mapper, mapper); + const typeArguments = map(typeParameters, t => getMappedType(t, combinedMapper)); + const newAliasSymbol = aliasSymbol || type.aliasSymbol; + const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + const id = (type.objectFlags & ObjectFlags.SingleSignatureType ? "S" : "") + getTypeListId(typeArguments) + getAliasId(newAliasSymbol, newAliasTypeArguments); + if (!target.instantiations) { + target.instantiations = new Map(); + target.instantiations.set(getTypeListId(typeParameters) + getAliasId(target.aliasSymbol, target.aliasTypeArguments), target); + } + let result = target.instantiations.get(id); + if (!result) { + if (type.objectFlags & ObjectFlags.SingleSignatureType) { + result = instantiateAnonymousType(type, mapper); + target.instantiations.set(id, result); + return result; + } + const newMapper = createTypeMapper(typeParameters, typeArguments); + result = target.objectFlags & ObjectFlags.Reference ? createDeferredTypeReference((type as DeferredTypeReference).target, (type as DeferredTypeReference).node, newMapper, newAliasSymbol, newAliasTypeArguments) : + target.objectFlags & ObjectFlags.Mapped ? instantiateMappedType(target as MappedType, newMapper, newAliasSymbol, newAliasTypeArguments) : + instantiateAnonymousType(target, newMapper, newAliasSymbol, newAliasTypeArguments); + target.instantiations.set(id, result); // Set cached result early in case we recursively invoke instantiation while eagerly computing type variable visibility below + const resultObjectFlags = getObjectFlags(result); + if (result.flags & TypeFlags.ObjectFlagsType && !(resultObjectFlags & ObjectFlags.CouldContainTypeVariablesComputed)) { + const resultCouldContainTypeVariables = some(typeArguments, couldContainTypeVariables); // one of the input type arguments might be or contain the result + if (!(getObjectFlags(result) & ObjectFlags.CouldContainTypeVariablesComputed)) { + // if `result` is one of the object types we tried to make (it may not be, due to how `instantiateMappedType` works), we can carry forward the type variable containment check from the input type arguments + if (resultObjectFlags & (ObjectFlags.Mapped | ObjectFlags.Anonymous | ObjectFlags.Reference)) { + (result as ObjectFlagsType).objectFlags |= ObjectFlags.CouldContainTypeVariablesComputed | (resultCouldContainTypeVariables ? ObjectFlags.CouldContainTypeVariables : 0); + } + // If none of the type arguments for the outer type parameters contain type variables, it follows + // that the instantiated type doesn't reference type variables. + // Intrinsics have `CouldContainTypeVariablesComputed` pre-set, so this should only cover unions and intersections resulting from `instantiateMappedType` + else { + (result as ObjectFlagsType).objectFlags |= !resultCouldContainTypeVariables ? ObjectFlags.CouldContainTypeVariablesComputed : 0; + } + } + } + } + return result; + } + return type; + } + + function maybeTypeParameterReference(node: Node) { + return !(node.parent.kind === SyntaxKind.TypeReference && (node.parent as TypeReferenceNode).typeArguments && node === (node.parent as TypeReferenceNode).typeName || + node.parent.kind === SyntaxKind.ImportType && (node.parent as ImportTypeNode).typeArguments && node === (node.parent as ImportTypeNode).qualifier); + } + + function isTypeParameterPossiblyReferenced(tp: TypeParameter, node: Node) { + // If the type parameter doesn't have exactly one declaration, if there are intervening statement blocks + // between the node and the type parameter declaration, if the node contains actual references to the + // type parameter, or if the node contains type queries that we can't prove couldn't contain references to the type parameter, + // we consider the type parameter possibly referenced. + if (tp.symbol && tp.symbol.declarations && tp.symbol.declarations.length === 1) { + const container = tp.symbol.declarations[0].parent; + for (let n = node; n !== container; n = n.parent) { + if (!n || n.kind === SyntaxKind.Block || n.kind === SyntaxKind.ConditionalType && forEachChild((n as ConditionalTypeNode).extendsType, containsReference)) { + return true; + } + } + return containsReference(node); + } + return true; + function containsReference(node: Node): boolean { + switch (node.kind) { + case SyntaxKind.ThisType: + return !!tp.isThisType; + case SyntaxKind.Identifier: + return !tp.isThisType && isPartOfTypeNode(node) && maybeTypeParameterReference(node) && + getTypeFromTypeNodeWorker(node as TypeNode) === tp; // use worker because we're looking for === equality + case SyntaxKind.TypeQuery: + const entityName = (node as TypeQueryNode).exprName; + const firstIdentifier = getFirstIdentifier(entityName); + if (!isThisIdentifier(firstIdentifier)) { // Don't attempt to analyze typeof this.xxx + const firstIdentifierSymbol = getResolvedSymbol(firstIdentifier); + const tpDeclaration = tp.symbol.declarations![0]; // There is exactly one declaration, otherwise `containsReference` is not called + const tpScope = tpDeclaration.kind === SyntaxKind.TypeParameter ? tpDeclaration.parent : // Type parameter is a regular type parameter, e.g. foo + tp.isThisType ? tpDeclaration : // Type parameter is the this type, and its declaration is the class declaration. + undefined; // Type parameter's declaration was unrecognized, e.g. comes from JSDoc annotation. + if (firstIdentifierSymbol.declarations && tpScope) { + return some(firstIdentifierSymbol.declarations, idDecl => isNodeDescendantOf(idDecl, tpScope)) || + some((node as TypeQueryNode).typeArguments, containsReference); + } + } + return true; + case SyntaxKind.MethodDeclaration: + case SyntaxKind.MethodSignature: + return !(node as FunctionLikeDeclaration).type && !!(node as FunctionLikeDeclaration).body || + some((node as FunctionLikeDeclaration).typeParameters, containsReference) || + some((node as FunctionLikeDeclaration).parameters, containsReference) || + !!(node as FunctionLikeDeclaration).type && containsReference((node as FunctionLikeDeclaration).type!); + } + return !!forEachChild(node, containsReference); + } + } + + function getHomomorphicTypeVariable(type: MappedType) { + const constraintType = getConstraintTypeFromMappedType(type); + if (constraintType.flags & TypeFlags.Index) { + const typeVariable = getActualTypeVariable((constraintType as IndexType).type); + if (typeVariable.flags & TypeFlags.TypeParameter) { + return typeVariable as TypeParameter; + } + } + return undefined; + } + + function instantiateMappedType(type: MappedType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + // For a homomorphic mapped type { [P in keyof T]: X }, where T is some type variable, the mapping + // operation depends on T as follows: + // * If T is a primitive type no mapping is performed and the result is simply T. + // * If T is a union type we distribute the mapped type over the union. + // * If T is an array we map to an array where the element type has been transformed. + // * If T is a tuple we map to a tuple where the element types have been transformed. + // * If T is an intersection of array or tuple types we map to an intersection of transformed array or tuple types. + // * Otherwise we map to an object type where the type of each property has been transformed. + // For example, when T is instantiated to a union type A | B, we produce { [P in keyof A]: X } | + // { [P in keyof B]: X }, and when when T is instantiated to a union type A | undefined, we produce + // { [P in keyof A]: X } | undefined. + const typeVariable = getHomomorphicTypeVariable(type); + if (typeVariable) { + const mappedTypeVariable = instantiateType(typeVariable, mapper); + if (typeVariable !== mappedTypeVariable) { + return mapTypeWithAlias(getReducedType(mappedTypeVariable), instantiateConstituent, aliasSymbol, aliasTypeArguments); + } + } + // If the constraint type of the instantiation is the wildcard type, return the wildcard type. + return instantiateType(getConstraintTypeFromMappedType(type), mapper) === wildcardType ? wildcardType : instantiateAnonymousType(type, mapper, aliasSymbol, aliasTypeArguments); + + function instantiateConstituent(t: Type): Type { + if (t.flags & (TypeFlags.AnyOrUnknown | TypeFlags.InstantiableNonPrimitive | TypeFlags.Object | TypeFlags.Intersection) && t !== wildcardType && !isErrorType(t)) { + if (!type.declaration.nameType) { + let constraint; + if ( + isArrayType(t) || t.flags & TypeFlags.Any && findResolutionCycleStartIndex(typeVariable!, TypeSystemPropertyName.ImmediateBaseConstraint) < 0 && + (constraint = getConstraintOfTypeParameter(typeVariable!)) && everyType(constraint, isArrayOrTupleType) + ) { + return instantiateMappedArrayType(t, type, prependTypeMapping(typeVariable!, t, mapper)); + } + if (isTupleType(t)) { + return instantiateMappedTupleType(t, type, typeVariable!, mapper); + } + if (isArrayOrTupleOrIntersection(t)) { + return getIntersectionType(map((t as IntersectionType).types, instantiateConstituent)); + } + } + return instantiateAnonymousType(type, prependTypeMapping(typeVariable!, t, mapper)); + } + return t; + } + } + + function getModifiedReadonlyState(state: boolean, modifiers: MappedTypeModifiers) { + return modifiers & MappedTypeModifiers.IncludeReadonly ? true : modifiers & MappedTypeModifiers.ExcludeReadonly ? false : state; + } + + function instantiateMappedTupleType(tupleType: TupleTypeReference, mappedType: MappedType, typeVariable: TypeVariable, mapper: TypeMapper) { + // We apply the mapped type's template type to each of the fixed part elements. For variadic elements, we + // apply the mapped type itself to the variadic element type. For other elements in the variable part of the + // tuple, we surround the element type with an array type and apply the mapped type to that. This ensures + // that we get sequential property key types for the fixed part of the tuple, and property key type number + // for the remaining elements. For example + // + // type Keys = { [K in keyof T]: K }; + // type Foo = Keys<[string, string, ...T, string]>; // ["0", "1", ...Keys, number] + // + const elementFlags = tupleType.target.elementFlags; + const fixedLength = tupleType.target.fixedLength; + const fixedMapper = fixedLength ? prependTypeMapping(typeVariable, tupleType, mapper) : mapper; + const newElementTypes = map(getElementTypes(tupleType), (type, i) => { + const flags = elementFlags[i]; + return i < fixedLength ? instantiateMappedTypeTemplate(mappedType, getStringLiteralType("" + i), !!(flags & ElementFlags.Optional), fixedMapper) : + flags & ElementFlags.Variadic ? instantiateType(mappedType, prependTypeMapping(typeVariable, type, mapper)) : + getElementTypeOfArrayType(instantiateType(mappedType, prependTypeMapping(typeVariable, createArrayType(type), mapper))) ?? unknownType; + }); + const modifiers = getMappedTypeModifiers(mappedType); + const newElementFlags = modifiers & MappedTypeModifiers.IncludeOptional ? map(elementFlags, f => f & ElementFlags.Required ? ElementFlags.Optional : f) : + modifiers & MappedTypeModifiers.ExcludeOptional ? map(elementFlags, f => f & ElementFlags.Optional ? ElementFlags.Required : f) : + elementFlags; + const newReadonly = getModifiedReadonlyState(tupleType.target.readonly, getMappedTypeModifiers(mappedType)); + return contains(newElementTypes, errorType) ? errorType : + createTupleType(newElementTypes, newElementFlags, newReadonly, tupleType.target.labeledElementDeclarations); + } + + function instantiateMappedArrayType(arrayType: Type, mappedType: MappedType, mapper: TypeMapper) { + const elementType = instantiateMappedTypeTemplate(mappedType, numberType, /*isOptional*/ true, mapper); + return isErrorType(elementType) ? errorType : + createArrayType(elementType, getModifiedReadonlyState(isReadonlyArrayType(arrayType), getMappedTypeModifiers(mappedType))); + } + + function instantiateMappedTypeTemplate(type: MappedType, key: Type, isOptional: boolean, mapper: TypeMapper) { + const templateMapper = appendTypeMapping(mapper, getTypeParameterFromMappedType(type), key); + const propType = instantiateType(getTemplateTypeFromMappedType(type.target as MappedType || type), templateMapper); + const modifiers = getMappedTypeModifiers(type); + return strictNullChecks && modifiers & MappedTypeModifiers.IncludeOptional && !maybeTypeOfKind(propType, TypeFlags.Undefined | TypeFlags.Void) ? getOptionalType(propType, /*isProperty*/ true) : + strictNullChecks && modifiers & MappedTypeModifiers.ExcludeOptional && isOptional ? getTypeWithFacts(propType, TypeFacts.NEUndefined) : + propType; + } + + function instantiateAnonymousType(type: AnonymousType, mapper: TypeMapper, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): AnonymousType { + Debug.assert(type.symbol, "anonymous type must have symbol to be instantiated"); + const result = createObjectType(type.objectFlags & ~(ObjectFlags.CouldContainTypeVariablesComputed | ObjectFlags.CouldContainTypeVariables) | ObjectFlags.Instantiated, type.symbol) as AnonymousType; + if (type.objectFlags & ObjectFlags.Mapped) { + (result as MappedType).declaration = (type as MappedType).declaration; + // C.f. instantiateSignature + const origTypeParameter = getTypeParameterFromMappedType(type as MappedType); + const freshTypeParameter = cloneTypeParameter(origTypeParameter); + (result as MappedType).typeParameter = freshTypeParameter; + mapper = combineTypeMappers(makeUnaryTypeMapper(origTypeParameter, freshTypeParameter), mapper); + freshTypeParameter.mapper = mapper; + } + if (type.objectFlags & ObjectFlags.InstantiationExpressionType) { + (result as InstantiationExpressionType).node = (type as InstantiationExpressionType).node; + } + if (type.objectFlags & ObjectFlags.SingleSignatureType) { + (result as SingleSignatureType).outerTypeParameters = (type as SingleSignatureType).outerTypeParameters; + } + result.target = type; + result.mapper = mapper; + result.aliasSymbol = aliasSymbol || type.aliasSymbol; + result.aliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + result.objectFlags |= result.aliasTypeArguments ? getPropagatingFlagsOfTypes(result.aliasTypeArguments) : 0; + return result; + } + + function getConditionalTypeInstantiation(type: ConditionalType, mapper: TypeMapper, forConstraint: boolean, aliasSymbol?: Symbol, aliasTypeArguments?: readonly Type[]): Type { + const root = type.root; + if (root.outerTypeParameters) { + // We are instantiating a conditional type that has one or more type parameters in scope. Apply the + // mapper to the type parameters to produce the effective list of type arguments, and compute the + // instantiation cache key from the type IDs of the type arguments. + const typeArguments = map(root.outerTypeParameters, t => getMappedType(t, mapper)); + const id = (forConstraint ? "C" : "") + getTypeListId(typeArguments) + getAliasId(aliasSymbol, aliasTypeArguments); + let result = root.instantiations!.get(id); + if (!result) { + const newMapper = createTypeMapper(root.outerTypeParameters, typeArguments); + const checkType = root.checkType; + const distributionType = root.isDistributive ? getReducedType(getMappedType(checkType, newMapper)) : undefined; + // Distributive conditional types are distributed over union types. For example, when the + // distributive conditional type T extends U ? X : Y is instantiated with A | B for T, the + // result is (A extends U ? X : Y) | (B extends U ? X : Y). + result = distributionType && checkType !== distributionType && distributionType.flags & (TypeFlags.Union | TypeFlags.Never) ? + mapTypeWithAlias(distributionType, t => getConditionalType(root, prependTypeMapping(checkType, t, newMapper), forConstraint), aliasSymbol, aliasTypeArguments) : + getConditionalType(root, newMapper, forConstraint, aliasSymbol, aliasTypeArguments); + root.instantiations!.set(id, result); + } + return result; + } + return type; + } + + function instantiateType(type: Type, mapper: TypeMapper | undefined): Type; + function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined; + function instantiateType(type: Type | undefined, mapper: TypeMapper | undefined): Type | undefined { + return type && mapper ? instantiateTypeWithAlias(type, mapper, /*aliasSymbol*/ undefined, /*aliasTypeArguments*/ undefined) : type; + } + + function instantiateTypeWithAlias(type: Type, mapper: TypeMapper, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined): Type { + if (!couldContainTypeVariables(type)) { + return type; + } + if (instantiationDepth === 100 || instantiationCount >= 5000000) { + // We have reached 100 recursive type instantiations, or 5M type instantiations caused by the same statement + // or expression. There is a very high likelyhood we're dealing with a combination of infinite generic types + // that perpetually generate new type identities, so we stop the recursion here by yielding the error type. + tracing?.instant(tracing.Phase.CheckTypes, "instantiateType_DepthLimit", { typeId: type.id, instantiationDepth, instantiationCount }); + error(currentNode, Diagnostics.Type_instantiation_is_excessively_deep_and_possibly_infinite); + return errorType; + } + totalInstantiationCount++; + instantiationCount++; + instantiationDepth++; + const result = instantiateTypeWorker(type, mapper, aliasSymbol, aliasTypeArguments); + instantiationDepth--; + return result; + } + + function instantiateTypeWorker(type: Type, mapper: TypeMapper, aliasSymbol: Symbol | undefined, aliasTypeArguments: readonly Type[] | undefined): Type { + const flags = type.flags; + if (flags & TypeFlags.TypeParameter) { + return getMappedType(type, mapper); + } + if (flags & TypeFlags.Object) { + const objectFlags = (type as ObjectType).objectFlags; + if (objectFlags & (ObjectFlags.Reference | ObjectFlags.Anonymous | ObjectFlags.Mapped)) { + if (objectFlags & ObjectFlags.Reference && !(type as TypeReference).node) { + const resolvedTypeArguments = (type as TypeReference).resolvedTypeArguments; + const newTypeArguments = instantiateTypes(resolvedTypeArguments, mapper); + return newTypeArguments !== resolvedTypeArguments ? createNormalizedTypeReference((type as TypeReference).target, newTypeArguments) : type; + } + if (objectFlags & ObjectFlags.ReverseMapped) { + return instantiateReverseMappedType(type as ReverseMappedType, mapper); + } + return getObjectTypeInstantiation(type as TypeReference | AnonymousType | MappedType, mapper, aliasSymbol, aliasTypeArguments); + } + return type; + } + if (flags & TypeFlags.UnionOrIntersection) { + const origin = type.flags & TypeFlags.Union ? (type as UnionType).origin : undefined; + const types = origin && origin.flags & TypeFlags.UnionOrIntersection ? (origin as UnionOrIntersectionType).types : (type as UnionOrIntersectionType).types; + const newTypes = instantiateTypes(types, mapper); + if (newTypes === types && aliasSymbol === type.aliasSymbol) { + return type; + } + const newAliasSymbol = aliasSymbol || type.aliasSymbol; + const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + return flags & TypeFlags.Intersection || origin && origin.flags & TypeFlags.Intersection ? + getIntersectionType(newTypes, IntersectionFlags.None, newAliasSymbol, newAliasTypeArguments) : + getUnionType(newTypes, UnionReduction.Literal, newAliasSymbol, newAliasTypeArguments); + } + if (flags & TypeFlags.Index) { + return getIndexType(instantiateType((type as IndexType).type, mapper)); + } + if (flags & TypeFlags.TemplateLiteral) { + return getTemplateLiteralType((type as TemplateLiteralType).texts, instantiateTypes((type as TemplateLiteralType).types, mapper)); + } + if (flags & TypeFlags.StringMapping) { + return getStringMappingType((type as StringMappingType).symbol, instantiateType((type as StringMappingType).type, mapper)); + } + if (flags & TypeFlags.IndexedAccess) { + const newAliasSymbol = aliasSymbol || type.aliasSymbol; + const newAliasTypeArguments = aliasSymbol ? aliasTypeArguments : instantiateTypes(type.aliasTypeArguments, mapper); + return getIndexedAccessType(instantiateType((type as IndexedAccessType).objectType, mapper), instantiateType((type as IndexedAccessType).indexType, mapper), (type as IndexedAccessType).accessFlags, /*accessNode*/ undefined, newAliasSymbol, newAliasTypeArguments); + } + if (flags & TypeFlags.Conditional) { + return getConditionalTypeInstantiation(type as ConditionalType, combineTypeMappers((type as ConditionalType).mapper, mapper), /*forConstraint*/ false, aliasSymbol, aliasTypeArguments); + } + if (flags & TypeFlags.Substitution) { + const newBaseType = instantiateType((type as SubstitutionType).baseType, mapper); + if (isNoInferType(type)) { + return getNoInferType(newBaseType); + } + const newConstraint = instantiateType((type as SubstitutionType).constraint, mapper); + // A substitution type originates in the true branch of a conditional type and can be resolved + // to just the base type in the same cases as the conditional type resolves to its true branch + // (because the base type is then known to satisfy the constraint). + if (newBaseType.flags & TypeFlags.TypeVariable && isGenericType(newConstraint)) { + return getSubstitutionType(newBaseType, newConstraint); + } + if (newConstraint.flags & TypeFlags.AnyOrUnknown || isTypeAssignableTo(getRestrictiveInstantiation(newBaseType), getRestrictiveInstantiation(newConstraint))) { + return newBaseType; + } + return newBaseType.flags & TypeFlags.TypeVariable ? getSubstitutionType(newBaseType, newConstraint) : getIntersectionType([newConstraint, newBaseType]); + } + return type; + } + + function instantiateReverseMappedType(type: ReverseMappedType, mapper: TypeMapper) { + const innerMappedType = instantiateType(type.mappedType, mapper); + if (!(getObjectFlags(innerMappedType) & ObjectFlags.Mapped)) { + return type; + } + const innerIndexType = instantiateType(type.constraintType, mapper); + if (!(innerIndexType.flags & TypeFlags.Index)) { + return type; + } + const instantiated = inferTypeForHomomorphicMappedType( + instantiateType(type.source, mapper), + innerMappedType as MappedType, + innerIndexType as IndexType, + ); + if (instantiated) { + return instantiated; + } + return type; // Nested invocation of `inferTypeForHomomorphicMappedType` or the `source` instantiated into something unmappable + } + + function getPermissiveInstantiation(type: Type) { + return type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never) ? type : + type.permissiveInstantiation || (type.permissiveInstantiation = instantiateType(type, permissiveMapper)); + } + + function getRestrictiveInstantiation(type: Type) { + if (type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never)) { + return type; + } + if (type.restrictiveInstantiation) { + return type.restrictiveInstantiation; + } + type.restrictiveInstantiation = instantiateType(type, restrictiveMapper); + // We set the following so we don't attempt to set the restrictive instance of a restrictive instance + // which is redundant - we'll produce new type identities, but all type params have already been mapped. + // This also gives us a way to detect restrictive instances upon comparisons and _disable_ the "distributeive constraint" + // assignability check for them, which is distinctly unsafe, as once you have a restrctive instance, all the type parameters + // are constrained to `unknown` and produce tons of false positives/negatives! + type.restrictiveInstantiation.restrictiveInstantiation = type.restrictiveInstantiation; + return type.restrictiveInstantiation; + } + + function instantiateIndexInfo(info: IndexInfo, mapper: TypeMapper) { + return createIndexInfo(info.keyType, instantiateType(info.type, mapper), info.isReadonly, info.declaration); + } + + // Returns true if the given expression contains (at any level of nesting) a function or arrow expression + // that is subject to contextual typing. + function isContextSensitive(node: Expression | MethodDeclaration | ObjectLiteralElementLike | JsxAttributeLike | JsxChild): boolean { + Debug.assert(node.kind !== SyntaxKind.MethodDeclaration || isObjectLiteralMethod(node)); + switch (node.kind) { + case SyntaxKind.FunctionExpression: + case SyntaxKind.ArrowFunction: + case SyntaxKind.MethodDeclaration: + case SyntaxKind.FunctionDeclaration: // Function declarations can have context when annotated with a jsdoc @type + return isContextSensitiveFunctionLikeDeclaration(node as FunctionExpression | ArrowFunction | MethodDeclaration); + case SyntaxKind.ObjectLiteralExpression: + return some((node as ObjectLiteralExpression).properties, isContextSensitive); + case SyntaxKind.ArrayLiteralExpression: + return some((node as ArrayLiteralExpression).elements, isContextSensitive); + case SyntaxKind.ConditionalExpression: + return isContextSensitive((node as ConditionalExpression).whenTrue) || + isContextSensitive((node as ConditionalExpression).whenFalse); + case SyntaxKind.BinaryExpression: + return ((node as BinaryExpression).operatorToken.kind === SyntaxKind.BarBarToken || (node as BinaryExpression).operatorToken.kind === SyntaxKind.QuestionQuestionToken) && + (isContextSensitive((node as BinaryExpression).left) || isContextSensitive((node as BinaryExpression).right)); + case SyntaxKind.PropertyAssignment: + return isContextSensitive((node as PropertyAssignment).initializer); + case SyntaxKind.ParenthesizedExpression: + return isContextSensitive((node as ParenthesizedExpression).expression); + case SyntaxKind.JsxAttributes: + return some((node as JsxAttributes).properties, isContextSensitive) || isJsxOpeningElement(node.parent) && some(node.parent.parent.children, isContextSensitive); + case SyntaxKind.JsxAttribute: { + // If there is no initializer, JSX attribute has a boolean value of true which is not context sensitive. + const { initializer } = node as JsxAttribute; + return !!initializer && isContextSensitive(initializer); + } + case SyntaxKind.JsxExpression: { + // It is possible to that node.expression is undefined (e.g