fix https://github.com/microsoft/vscode/issues/106308

src/vs/editor/contrib/links/getLinks.ts

@@ -13,6 +13,7 @@ import { IModelService } from 'vs/editor/common/services/modelService';
 import { CommandsRegistry } from 'vs/platform/commands/common/commands';
 import { isDisposable, Disposable } from 'vs/base/common/lifecycle';
 import { coalesce } from 'vs/base/common/arrays';
+import { assertType } from 'vs/base/common/types';
 
 export class Link implements ILink {
 
@@ -152,10 +153,13 @@ export function getLinks(model: ITextModel, token: CancellationToken): Promise<L
 
 
 CommandsRegistry.registerCommand('_executeLinkProvider', async (accessor, ...args): Promise<ILink[]> => {
-	const [uri] = args;
-	if (!(uri instanceof URI)) {
-		return [];
+	let [uri, resolveCount] = args;
+	assertType(uri instanceof URI);
+
+	if (typeof resolveCount !== 'number') {
+		resolveCount = 0;
 	}
+
 	const model = accessor.get(IModelService).getModel(uri);
 	if (!model) {
 		return [];
@@ -164,6 +168,12 @@ CommandsRegistry.registerCommand('_executeLinkProvider', async (accessor, ...arg
 	if (!list) {
 		return [];
 	}
+
+	// resolve links
+	for (let i = 0; i < Math.min(resolveCount, list.links.length); i++) {
+		await list.links[i].resolve(CancellationToken.None);
+	}
+
 	const result = list.links.slice(0);
 	list.dispose();
 	return result;

src/vs/workbench/api/common/extHostApiCommands.ts

@@ -228,10 +228,15 @@ const newCommands: ApiCommand[] = [
 			}
 			return typeConverters.WorkspaceEdit.to(value);
 		})
+	),
+	// --- links
+	new ApiCommand(
+		'vscode.executeLinkProvider', '_executeLinkProvider', 'Execute document link provider.',
+		[ApiCommandArgument.Uri, new ApiCommandArgument('linkResolveCount', '(optional) Number of links that should be resolved, only when links are unresolved.', v => typeof v === 'number' || typeof v === 'undefined', v => v)],
+		new ApiCommandResult<modes.ILink[], vscode.DocumentLink[]>('A promise that resolves to an array of DocumentLink-instances.', value => value.map(typeConverters.DocumentLink.to))
 	)
 ];
 
-
 //#endregion
 
 
@@ -289,13 +294,6 @@ export class ExtHostApiCommands {
 			returns: 'A promise that resolves to an array of CodeLens-instances.'
 		});
 
-		this._register('vscode.executeLinkProvider', this._executeDocumentLinkProvider, {
-			description: 'Execute document link provider.',
-			args: [
-				{ name: 'uri', description: 'Uri of a text document', constraint: URI }
-			],
-			returns: 'A promise that resolves to an array of DocumentLink-instances.'
-		});
 		this._register('vscode.executeDocumentColorProvider', this._executeDocumentColorProvider, {
 			description: 'Execute document color provider.',
 			args: [
@@ -478,12 +476,6 @@ export class ExtHostApiCommands {
 					typeConverters.Range.to(item.range),
 					item.command ? this._commands.converter.fromInternal(item.command) : undefined);
 			}));
-
-	}
-
-	private _executeDocumentLinkProvider(resource: URI): Promise<vscode.DocumentLink[] | undefined> {
-		return this._commands.executeCommand<modes.ILink[]>('_executeLinkProvider', resource)
-			.then(tryMapWith(typeConverters.DocumentLink.to));
 	}
 }
 

src/vs/workbench/test/browser/api/extHostApiCommands.test.ts

@@ -1011,6 +1011,29 @@ suite('ExtHostLanguageFeatureCommands', function () {
 		});
 	});
 
+	test('What\'s the condition for DocumentLink target to be undefined? #106308', async function () {
+		disposables.push(extHost.registerDocumentLinkProvider(nullExtensionDescription, defaultSelector, <vscode.DocumentLinkProvider>{
+			provideDocumentLinks(): any {
+				return [new types.DocumentLink(new types.Range(0, 0, 0, 20), undefined)];
+			},
+			resolveDocumentLink(link) {
+				link.target = URI.parse('foo:bar');
+				return link;
+			}
+		}));
+
+		await rpcProtocol.sync();
+
+		const links1 = await commands.executeCommand<vscode.DocumentLink[]>('vscode.executeLinkProvider', model.uri);
+		assert.equal(links1.length, 1);
+		assert.equal(links1[0].target, undefined);
+
+		const links2 = await commands.executeCommand<vscode.DocumentLink[]>('vscode.executeLinkProvider', model.uri, 1000);
+		assert.equal(links2.length, 1);
+		assert.equal(links2[0].target!.toString(), URI.parse('foo:bar').toString());
+
+	});
+
 
 	test('Color provider', function () {