ILanguageSelection should not be IDisposable (#119968)

src/vs/editor/common/services/modeService.ts

@@ -4,7 +4,6 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { Event } from 'vs/base/common/event';
-import { IDisposable } from 'vs/base/common/lifecycle';
 import { URI } from 'vs/base/common/uri';
 import { IMode, LanguageId, LanguageIdentifier } from 'vs/editor/common/modes';
 import { createDecorator } from 'vs/platform/instantiation/common/instantiation';
@@ -22,7 +21,7 @@ export interface ILanguageExtensionPoint {
 	configuration?: URI;
 }
 
-export interface ILanguageSelection extends IDisposable {
+export interface ILanguageSelection {
 	readonly languageIdentifier: LanguageIdentifier;
 	readonly onDidChange: Event<LanguageIdentifier>;
 }

src/vs/editor/common/services/modeServiceImpl.ts

@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { Emitter, Event } from 'vs/base/common/event';
-import { Disposable } from 'vs/base/common/lifecycle';
+import { Disposable, IDisposable } from 'vs/base/common/lifecycle';
 import { URI } from 'vs/base/common/uri';
 import { IMode, LanguageId, LanguageIdentifier } from 'vs/editor/common/modes';
 import { FrankensteinMode } from 'vs/editor/common/modes/abstractMode';
@@ -13,20 +13,28 @@ import { LanguagesRegistry } from 'vs/editor/common/services/languagesRegistry';
 import { ILanguageSelection, IModeService } from 'vs/editor/common/services/modeService';
 import { firstOrDefault } from 'vs/base/common/arrays';
 
-class LanguageSelection extends Disposable implements ILanguageSelection {
+class LanguageSelection implements ILanguageSelection {
 
 	public languageIdentifier: LanguageIdentifier;
 
 	private readonly _selector: () => LanguageIdentifier;
-
-	private readonly _onDidChange: Emitter<LanguageIdentifier> = this._register(new Emitter<LanguageIdentifier>());
-	public readonly onDidChange: Event<LanguageIdentifier> = this._onDidChange.event;
+	private readonly _onDidChange: Emitter<LanguageIdentifier>;
+	public readonly onDidChange: Event<LanguageIdentifier>;
 
 	constructor(onLanguagesMaybeChanged: Event<void>, selector: () => LanguageIdentifier) {
-		super();
 		this._selector = selector;
 		this.languageIdentifier = this._selector();
-		this._register(onLanguagesMaybeChanged(() => this._evaluate()));
+
+		let listener: IDisposable;
+		this._onDidChange = new Emitter<LanguageIdentifier>({
+			onFirstListenerAdd: () => {
+				listener = onLanguagesMaybeChanged(() => this._evaluate());
+			},
+			onLastListenerRemove: () => {
+				listener.dispose();
+			}
+		});
+		this.onDidChange = this._onDidChange.event;
 	}
 
 	private _evaluate(): void {

src/vs/editor/common/services/modelServiceImpl.ts

@@ -78,10 +78,6 @@ class ModelData implements IDisposable {
 			this._languageSelectionListener.dispose();
 			this._languageSelectionListener = null;
 		}
-		if (this._languageSelection) {
-			this._languageSelection.dispose();
-			this._languageSelection = null;
-		}
 	}
 
 	public dispose(): void {

src/vs/editor/test/common/mocks/mockMode.ts

@@ -28,5 +28,4 @@ export class MockMode extends Disposable implements IMode {
 export class StaticLanguageSelector implements ILanguageSelection {
 	readonly onDidChange: Event<LanguageIdentifier> = Event.None;
 	constructor(public readonly languageIdentifier: LanguageIdentifier) { }
-	public dispose(): void { }
 }

src/vs/workbench/contrib/performance/browser/perfviewEditor.ts

@@ -104,7 +104,6 @@ class PerfModelContentProvider implements ITextModelContentProvider {
 					this._model.setMode(e);
 				}
 			}));
-			this._modelDisposables.push(langId);
 			this._modelDisposables.push(this._extensionService.onDidChangeExtensionsStatus(this._updateModel, this));
 
 			writeTransientState(this._model, { wordWrapOverride: 'off' }, this._editorService);