Avoid uri parse warnings for markdown uris

Fixes #58566

We only support local file links or a small set of normal schemes, like `http` and `mailto`. Use this to avoid calling `Uri.parse` with scheme-less paths such as `Uri.parse('/images/cat.gif')`

extensions/markdown-language-features/src/features/documentLinkProvider.ts

@@ -3,34 +3,38 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-import * as vscode from 'vscode';
 import * as path from 'path';
+import * as vscode from 'vscode';
 import { OpenDocumentLinkCommand } from '../commands/openDocumentLink';
+import { getUriForLinkWithKnownExternalScheme } from '../util/links';
 
 function normalizeLink(
 	document: vscode.TextDocument,
 	link: string,
 	base: string
 ): vscode.Uri {
-	const uri = vscode.Uri.parse(link);
-	if (uri.scheme) {
-		return uri;
+	const externalSchemeUri = getUriForLinkWithKnownExternalScheme(link);
+	if (externalSchemeUri) {
+		return externalSchemeUri;
 	}
 
-	// assume it must be a file
-	let resourcePath = uri.path;
-	if (!uri.path) {
+	// Assume it must be an relative or absolute file path
+	// Use a fake scheme to avoid parse warnings
+	const tempUri = vscode.Uri.parse(`fake-scheme:${link}`);
+
+	let resourcePath = tempUri.path;
+	if (!tempUri.path) {
 		resourcePath = document.uri.path;
-	} else if (uri.path[0] === '/') {
+	} else if (tempUri.path[0] === '/') {
 		const root = vscode.workspace.getWorkspaceFolder(document.uri);
 		if (root) {
-			resourcePath = path.join(root.uri.fsPath, uri.path);
+			resourcePath = path.join(root.uri.fsPath, tempUri.path);
 		}
 	} else {
-		resourcePath = path.join(base, uri.path);
+		resourcePath = path.join(base, tempUri.path);
 	}
 
-	return OpenDocumentLinkCommand.createCommandUri(resourcePath, uri.fragment);
+	return OpenDocumentLinkCommand.createCommandUri(resourcePath, tempUri.fragment);
 }
 
 function matchAll(

extensions/markdown-language-features/src/markdownEngine.ts

@@ -8,6 +8,7 @@ import * as path from 'path';
 import * as vscode from 'vscode';
 import { MarkdownContributions } from './markdownExtensions';
 import { Slugifier } from './slugify';
+import { getUriForLinkWithKnownExternalScheme } from './util/links';
 
 const FrontMatterRegex = /^---\s*[^]*?(-{3}|\.{3})\s*/;
 
@@ -146,8 +147,17 @@ export class MarkdownEngine {
 		const normalizeLink = md.normalizeLink;
 		md.normalizeLink = (link: string) => {
 			try {
-				let uri = vscode.Uri.parse(link);
-				if (!uri.scheme && uri.path) {
+				const externalSchemeUri = getUriForLinkWithKnownExternalScheme(link);
+				if (externalSchemeUri) {
+					return normalizeLink(externalSchemeUri.toString());
+				}
+
+
+				// Assume it must be an relative or absolute file path
+				// Use a fake scheme to avoid parse warnings
+				let uri = vscode.Uri.parse(`fake-scheme:${link}`);
+
+				if (uri.path) {
 					// Assume it must be a file
 					const fragment = uri.fragment;
 					if (uri.path[0] === '/') {
@@ -165,7 +175,7 @@ export class MarkdownEngine {
 						});
 					}
 					return normalizeLink(uri.with({ scheme: 'vscode-resource' }).toString(true));
-				} else if (!uri.scheme && !uri.path && uri.fragment) {
+				} else if (!uri.path && uri.fragment) {
 					return normalizeLink(uri.with({
 						fragment: this.slugifier.fromHeading(uri.fragment).value
 					}).toString(true));

extensions/markdown-language-features/src/util/links.ts

@@ -0,0 +1,18 @@
+/*---------------------------------------------------------------------------------------------
+ *  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';
+
+const knownSchemes = ['http:', 'https:', 'file:', 'mailto:'];
+
+export function getUriForLinkWithKnownExternalScheme(
+	link: string,
+): vscode.Uri | undefined {
+	if (knownSchemes.some(knownScheme => link.toLowerCase().startsWith(knownScheme))) {
+		return vscode.Uri.parse(link);
+	}
+
+	return undefined;
+}