gracefully handle the case in which a delegate command has been disposed before execution, fixes #3265

src/vs/workbench/api/node/extHost.api.impl.ts

@@ -23,6 +23,7 @@ import {ExtHostMessageService} from 'vs/workbench/api/node/extHostMessageService
 import {ExtHostEditors} from 'vs/workbench/api/node/extHostEditors';
 import {ExtHostLanguages} from 'vs/workbench/api/node/extHostLanguages';
 import {ExtHostLanguageFeatures} from 'vs/workbench/api/node/extHostLanguageFeatures';
+import * as ExtHostTypeConverters from 'vs/workbench/api/node/extHostTypeConverters';
 import {registerApiCommands} from 'vs/workbench/api/node/extHostApiCommands';
 import * as extHostTypes from 'vs/workbench/api/node/extHostTypes';
 import Modes = require('vs/editor/common/modes');
@@ -148,6 +149,10 @@ export class ExtHostAPIImplementation {
 		const extHostStatusBar = new ExtHostStatusBar(this._threadService);
 		const extHostOutputService = new ExtHostOutputService(this._threadService);
 
+		// the converter might create delegate commands to avoid sending args
+		// around all the time
+		ExtHostTypeConverters.Command.initialize(extHostCommands);
+
 		// env namespace
 		let telemetryInfo: ITelemetryInfo;
 		this.env = Object.freeze({

src/vs/workbench/api/node/extHostLanguageFeatures.ts

@@ -87,7 +87,7 @@ class CodeLensAdapter implements modes.ICodeLensSupport {
 				data.symbols.push(<modes.ICodeLensSymbol>{
 					id: String(i),
 					range: TypeConverters.fromRange(lens.range),
-					command: TypeConverters.Command.from(lens.command, { commands: this._commands, disposables: data.disposables })
+					command: TypeConverters.Command.from(lens.command, data.disposables)
 				});
 			});
 
@@ -144,7 +144,7 @@ class CodeLensAdapter implements modes.ICodeLensSupport {
 					};
 				}
 
-				symbol.command = TypeConverters.Command.from(command, { commands: this._commands, disposables: cachedData.disposables });
+				symbol.command = TypeConverters.Command.from(command, cachedData.disposables);
 				return symbol;
 			});
 		});
@@ -315,7 +315,6 @@ class QuickFixAdapter implements modes.IQuickFixSupport {
 		});
 
 		this._cachedCommands = dispose(this._cachedCommands);
-		const ctx = { commands: this._commands, disposables: this._cachedCommands };
 
 		return asWinJsPromise(token => this._provider.provideCodeActions(doc, ran, { diagnostics: allDiagnostics }, token)).then(commands => {
 			if (!Array.isArray(commands)) {
@@ -323,7 +322,7 @@ class QuickFixAdapter implements modes.IQuickFixSupport {
 			}
 			return commands.map((command, i) => {
 				return <modes.IQuickFix> {
-					command: TypeConverters.Command.from(command, ctx),
+					command: TypeConverters.Command.from(command, this._cachedCommands),
 					score: i
 				};
 			});

src/vs/workbench/api/node/extHostTypeConverters.ts

@@ -494,10 +494,23 @@ export namespace SignatureHelp {
 
 export namespace Command {
 
+	const _delegateId = '_internal_delegate_command';
 	const _cache: { [id: string]: vscode.Command } = Object.create(null);
 	let _idPool = 1;
 
-	export function from(command: vscode.Command, context: { commands: ExtHostCommands; disposables: IDisposable[]; }): modes.ICommand {
+	export function initialize(commands: ExtHostCommands) {
+		return commands.registerCommand(_delegateId, (args: [string]) => {
+			const [id] = args;
+			const command = _cache[id];
+			if (!command) {
+				// handle already disposed delegations graceful
+				return;
+			}
+			return commands.executeCommand(command.command, ...command.arguments);
+		});
+	}
+
+	export function from(command: vscode.Command, disposables: IDisposable[]): modes.ICommand {
 
 		if (!command) {
 			return;
@@ -510,22 +523,29 @@ export namespace Command {
 
 		if (!isFalsyOrEmpty(command.arguments)) {
 
-			// keep command around
-			const id = `${command.command}-no-args-wrapper-${_idPool++}`;
-			result.id = id;
+			// redirect to delegate command and store actual command
+			const id = `delegate/${_idPool++}/for/${command.command}`;
+
+			result.id = _delegateId;
+			result.arguments = [id];
 			_cache[id] = command;
 
-			const disposable1 = context.commands.registerCommand(id, () => context.commands.executeCommand(command.command, ..._cache[id].arguments));
-			const disposable2 = { dispose() { delete _cache[id]; } };
-			context.disposables.push(disposable1, disposable2);
+			disposables.push({
+				dispose() {
+					delete _cache[id];
+				}
+			});
 		}
 
 		return result;
 	}
 
 	export function to(command: modes.ICommand): vscode.Command {
-
-		let result = _cache[command.id];
+		let result: vscode.Command;
+		if (command.id === _delegateId) {
+			let [key] = command.arguments;
+			result = _cache[key];
+		}
 		if (!result) {
 			result = {
 				command: command.id,