build: enable noImplicitOverride TypeScript option

The `noImplicitOverride` TypeScript option improves code quality by ensuring that properties from base classes are not accidentally overriden.
Reference: https://www.typescriptlang.org/tsconfig#noImplicitOverride

packages/angular/cli/commands/add-impl.ts

@@ -31,9 +31,9 @@ import { Schema as AddCommandSchema } from './add';
 const npa = require('npm-package-arg');
 
 export class AddCommand extends SchematicCommand<AddCommandSchema> {
-  readonly allowPrivateSchematics = true;
+  override readonly allowPrivateSchematics = true;
 
-  async initialize(options: AddCommandSchema & Arguments) {
+  override async initialize(options: AddCommandSchema & Arguments) {
     if (options.registry) {
       return super.initialize({ ...options, packageRegistry: options.registry });
     } else {
@@ -235,7 +235,7 @@ export class AddCommand extends SchematicCommand<AddCommandSchema> {
     return this.executeSchematic(collectionName, options['--']);
   }
 
-  async reportAnalytics(
+  override async reportAnalytics(
     paths: string[],
     options: AddCommandSchema & Arguments,
     dimensions: (boolean | number | string)[] = [],

packages/angular/cli/commands/build-impl.ts

@@ -11,9 +11,9 @@ import { Arguments } from '../models/interface';
 import { Schema as BuildCommandSchema } from './build';
 
 export class BuildCommand extends ArchitectCommand<BuildCommandSchema> {
-  public readonly target = 'build';
+  public override readonly target = 'build';
 
-  public async run(options: ArchitectCommandOptions & Arguments) {
+  public override async run(options: ArchitectCommandOptions & Arguments) {
     return this.runArchitectTarget(options);
   }
 }

packages/angular/cli/commands/deploy-impl.ts

@@ -25,10 +25,12 @@ Find more packages on npm https://www.npmjs.com/search?q=ng%20deploy
 `;
 
 export class DeployCommand extends ArchitectCommand<DeployCommandSchema> {
-  public readonly target = 'deploy';
+  public override readonly target = 'deploy';
-  public readonly missingTargetError = BuilderMissing;
+  public override readonly missingTargetError = BuilderMissing;
 
-  public async initialize(options: DeployCommandSchema & Arguments): Promise<number | void> {
+  public override async initialize(
+    options: DeployCommandSchema & Arguments,
+  ): Promise<number | void> {
     if (!options.help) {
       return super.initialize(options);
     }

packages/angular/cli/commands/e2e-impl.ts

@@ -11,9 +11,9 @@ import { Arguments } from '../models/interface';
 import { Schema as E2eCommandSchema } from './e2e';
 
 export class E2eCommand extends ArchitectCommand<E2eCommandSchema> {
-  public readonly target = 'e2e';
+  public override readonly target = 'e2e';
-  public readonly multiTarget = true;
+  public override readonly multiTarget = true;
-  public readonly missingTargetError = `
+  public override readonly missingTargetError = `
 Cannot find "e2e" target for the specified project.
 
 You should add a package that implements end-to-end testing capabilities.
@@ -26,7 +26,7 @@ For example:
 More options will be added to the list as they become available.
 `;
 
-  async initialize(options: E2eCommandSchema & Arguments) {
+  override async initialize(options: E2eCommandSchema & Arguments) {
     if (!options.help) {
       return super.initialize(options);
     }

packages/angular/cli/commands/extract-i18n-impl.ts

@@ -11,9 +11,9 @@ import { Arguments } from '../models/interface';
 import { Schema as ExtractI18nCommandSchema } from './extract-i18n';
 
 export class ExtractI18nCommand extends ArchitectCommand<ExtractI18nCommandSchema> {
-  public readonly target = 'extract-i18n';
+  public override readonly target = 'extract-i18n';
 
-  public async run(options: ExtractI18nCommandSchema & Arguments) {
+  public override async run(options: ExtractI18nCommandSchema & Arguments) {
     const version = process.version.substr(1).split('.');
     if (Number(version[0]) === 12 && Number(version[1]) === 0) {
       this.logger.error(

packages/angular/cli/commands/generate-impl.ts

@@ -16,7 +16,7 @@ export class GenerateCommand extends SchematicCommand<GenerateCommandSchema> {
   // Allows us to resolve aliases before reporting analytics
   longSchematicName: string | undefined;
 
-  async initialize(options: GenerateCommandSchema & Arguments) {
+  override async initialize(options: GenerateCommandSchema & Arguments) {
     // Fill up the schematics property of the command description.
     const [collectionName, schematicName] = await this.parseSchematicInfo(options);
     this.collectionName = collectionName;
@@ -75,7 +75,7 @@ export class GenerateCommand extends SchematicCommand<GenerateCommandSchema> {
     });
   }
 
-  async reportAnalytics(
+  override async reportAnalytics(
     paths: string[],
     options: GenerateCommandSchema & Arguments,
   ): Promise<void> {
@@ -104,7 +104,7 @@ export class GenerateCommand extends SchematicCommand<GenerateCommandSchema> {
     return [collectionName, schematicName];
   }
 
-  public async printHelp() {
+  public override async printHelp() {
     await super.printHelp();
 
     this.logger.info('');

packages/angular/cli/commands/lint-impl.ts

@@ -20,11 +20,11 @@ For example:
 `;
 
 export class LintCommand extends ArchitectCommand<LintCommandSchema> {
-  readonly target = 'lint';
+  override readonly target = 'lint';
-  readonly multiTarget = true;
+  override readonly multiTarget = true;
-  readonly missingTargetError = MissingBuilder;
+  override readonly missingTargetError = MissingBuilder;
 
-  async initialize(options: LintCommandSchema & Arguments): Promise<number | void> {
+  override async initialize(options: LintCommandSchema & Arguments): Promise<number | void> {
     if (!options.help) {
       return super.initialize(options);
     }

packages/angular/cli/commands/new-impl.ts

@@ -12,10 +12,10 @@ import { VERSION } from '../models/version';
 import { Schema as NewCommandSchema } from './new';
 
 export class NewCommand extends SchematicCommand<NewCommandSchema> {
-  public readonly allowMissingWorkspace = true;
+  public override readonly allowMissingWorkspace = true;
-  schematicName = 'ng-new';
+  override schematicName = 'ng-new';
 
-  async initialize(options: NewCommandSchema & Arguments) {
+  override async initialize(options: NewCommandSchema & Arguments) {
     this.collectionName = options.collection || (await this.getDefaultSchematicCollection());
 
     return super.initialize(options);

packages/angular/cli/commands/run-impl.ts

@@ -11,7 +11,7 @@ import { Arguments } from '../models/interface';
 import { Schema as RunCommandSchema } from './run';
 
 export class RunCommand extends ArchitectCommand<RunCommandSchema> {
-  public async run(options: ArchitectCommandOptions & Arguments) {
+  public override async run(options: ArchitectCommandOptions & Arguments) {
     if (options.target) {
       return this.runArchitectTarget(options);
     } else {

packages/angular/cli/commands/serve-impl.ts

@@ -11,13 +11,13 @@ import { Arguments } from '../models/interface';
 import { Schema as ServeCommandSchema } from './serve';
 
 export class ServeCommand extends ArchitectCommand<ServeCommandSchema> {
-  public readonly target = 'serve';
+  public override readonly target = 'serve';
 
   public validate() {
     return true;
   }
 
-  public async run(options: ArchitectCommandOptions & Arguments) {
+  public override async run(options: ArchitectCommandOptions & Arguments) {
     return this.runArchitectTarget(options);
   }
 }

packages/angular/cli/commands/test-impl.ts

@@ -11,10 +11,10 @@ import { Arguments } from '../models/interface';
 import { Schema as TestCommandSchema } from './test';
 
 export class TestCommand extends ArchitectCommand<TestCommandSchema> {
-  public readonly target = 'test';
+  public override readonly target = 'test';
-  public readonly multiTarget = true;
+  public override readonly multiTarget = true;
 
-  public async run(options: ArchitectCommandOptions & Arguments) {
+  public override async run(options: ArchitectCommandOptions & Arguments) {
     return this.runArchitectTarget(options);
   }
 }

packages/angular/cli/commands/update-impl.ts

@@ -63,11 +63,11 @@ const disableVersionCheck =
   disableVersionCheckEnv.toLowerCase() !== 'false';
 
 export class UpdateCommand extends Command<UpdateCommandSchema> {
-  public readonly allowMissingWorkspace = true;
+  public override readonly allowMissingWorkspace = true;
   private workflow!: NodeWorkflow;
   private packageManager = PackageManager.Npm;
 
-  async initialize(options: UpdateCommandSchema & Arguments) {
+  override async initialize(options: UpdateCommandSchema & Arguments) {
     this.packageManager = await getPackageManager(this.context.root);
     this.workflow = new NodeWorkflow(this.context.root, {
       packageManager: this.packageManager,

packages/angular/cli/models/architect-command.ts

@@ -28,7 +28,7 @@ export abstract class ArchitectCommand<
   protected _architect!: Architect;
   protected _architectHost!: WorkspaceNodeModulesArchitectHost;
   protected _registry!: json.schema.SchemaRegistry;
-  protected readonly useReportAnalytics = false;
+  protected override readonly useReportAnalytics = false;
 
   // If this command supports running multiple targets.
   protected multiTarget = false;
@@ -36,7 +36,7 @@ export abstract class ArchitectCommand<
   target: string | undefined;
   missingTargetError: string | undefined;
 
-  public async initialize(options: T & Arguments): Promise<number | void> {
+  public override async initialize(options: T & Arguments): Promise<number | void> {
     this._registry = new json.schema.CoreSchemaRegistry();
     this._registry.addPostTransform(json.schema.transforms.addUndefinedDefaults);
     this._registry.useXDeprecatedProvider((msg) => this.logger.warn(msg));

packages/angular/cli/models/schematic-command.ts

@@ -56,10 +56,10 @@ export class UnknownCollectionError extends Error {
 }
 
 export abstract class SchematicCommand<
-  T extends BaseSchematicSchema & BaseCommandOptions
+  T extends BaseSchematicSchema & BaseCommandOptions,
 > extends Command<T> {
   protected readonly allowPrivateSchematics: boolean = false;
-  protected readonly useReportAnalytics = false;
+  protected override readonly useReportAnalytics = false;
   protected _workflow!: NodeWorkflow;
 
   protected defaultCollectionName = '@schematics/angular';
@@ -70,7 +70,7 @@ export abstract class SchematicCommand<
     super(context, description, logger);
   }
 
-  public async initialize(options: T & Arguments) {
+  public override async initialize(options: T & Arguments) {
     await this.createWorkflow(options);
 
     if (this.schematicName) {
@@ -94,7 +94,7 @@ export abstract class SchematicCommand<
     }
   }
 
-  public async printHelp() {
+  public override async printHelp() {
     await super.printHelp();
     this.logger.info('');
 
@@ -138,7 +138,7 @@ export abstract class SchematicCommand<
     return 0;
   }
 
-  async printHelpUsage() {
+  override async printHelpUsage() {
     const subCommandOption = this.description.options.filter((x) => x.subcommands)[0];
 
     if (!subCommandOption || !subCommandOption.subcommands) {

packages/angular/cli/models/schematic-engine-host.ts

@@ -51,7 +51,7 @@ function shouldWrapSchematic(schematicFile: string): boolean {
 }
 
 export class SchematicEngineHost extends NodeModulesEngineHost {
-  protected _resolveReferenceString(refString: string, parentPath: string) {
+  protected override _resolveReferenceString(refString: string, parentPath: string) {
     const [path, name] = refString.split('#', 2);
     // Mimic behavior of ExportStringRef class used in default behavior
     const fullPath = path[0] === '.' ? resolve(parentPath ?? process.cwd(), path) : path;

packages/angular/cli/utilities/json-schema.ts

@@ -21,7 +21,7 @@ import {
 } from '../models/interface';
 
 export class CommandJsonPathException extends BaseException {
-  constructor(public readonly path: string, public readonly name: string) {
+  constructor(public readonly path: string, public override readonly name: string) {
     super(`File ${path} was not found while constructing the subcommand ${name}.`);
   }
 }
@@ -36,7 +36,7 @@ function _getEnumFromValue<E, T extends E[keyof E]>(
   }
 
   if (Object.values(enumeration).includes(value)) {
-    return (value as unknown) as T;
+    return value as unknown as T;
   }
 
   return defaultValue;

packages/angular_devkit/architect/src/architect.ts

@@ -215,7 +215,7 @@ class ArchitectBuilderJobRegistry implements BuilderRegistry {
  * A JobRegistry that resolves targets from the host.
  */
 class ArchitectTargetJobRegistry extends ArchitectBuilderJobRegistry {
-  get<A extends json.JsonObject, I extends BuilderInput, O extends BuilderOutput>(
+  override get<A extends json.JsonObject, I extends BuilderInput, O extends BuilderOutput>(
     name: string,
   ): Observable<experimental.jobs.JobHandler<A, I, O> | null> {
     const m = name.match(/^{([^:]+):([^:]+)(?::([^:]*))?}$/i);

packages/angular_devkit/build_angular/src/webpack/plugins/index-html-webpack-plugin.ts

@@ -34,7 +34,7 @@ export class IndexHtmlWebpackPlugin extends IndexHtmlGenerator {
     throw new Error('compilation is undefined.');
   }
 
-  constructor(readonly options: IndexHtmlWebpackPluginOptions) {
+  constructor(override readonly options: IndexHtmlWebpackPluginOptions) {
     super(options);
   }
 
@@ -101,13 +101,13 @@ export class IndexHtmlWebpackPlugin extends IndexHtmlGenerator {
     };
   }
 
-  async readAsset(path: string): Promise<string> {
+  override async readAsset(path: string): Promise<string> {
     const data = this.compilation.assets[basename(path)].source();
 
     return typeof data === 'string' ? data : data.toString();
   }
 
-  protected async readIndex(path: string): Promise<string> {
+  protected override async readIndex(path: string): Promise<string> {
     return new Promise<string>((resolve, reject) => {
       this.compilation.inputFileSystem.readFile(
         path,

packages/angular_devkit/core/node/testing/index.ts

@@ -17,7 +17,7 @@ import { NodeJsSyncHost } from '../host';
  */
 export class TempScopedNodeJsSyncHost extends virtualFs.ScopedHost<fs.Stats> {
   protected _sync?: virtualFs.SyncDelegateHost<fs.Stats>;
-  protected _root: Path;
+  protected override _root: Path;
 
   constructor() {
     const root = normalize(path.join(os.tmpdir(), `devkit-host-${+Date.now()}-${process.pid}`));

packages/angular_devkit/core/src/logger/level.ts

@@ -11,18 +11,18 @@ import { LogLevel, Logger } from './logger';
 
 export class LevelTransformLogger extends Logger {
   constructor(
-    public readonly name: string,
+    public override readonly name: string,
-    public readonly parent: Logger | null = null,
+    public override readonly parent: Logger | null = null,
     public readonly levelTransform: (level: LogLevel) => LogLevel,
   ) {
     super(name, parent);
   }
 
-  log(level: LogLevel, message: string, metadata: JsonObject = {}): void {
+  override log(level: LogLevel, message: string, metadata: JsonObject = {}): void {
     return super.log(this.levelTransform(level), message, metadata);
   }
 
-  createChild(name: string): Logger {
+  override createChild(name: string): Logger {
     return new LevelTransformLogger(name, this, this.levelTransform);
   }
 }
@@ -37,8 +37,8 @@ export class LevelCapLogger extends LevelTransformLogger {
   };
 
   constructor(
-    public readonly name: string,
+    public override readonly name: string,
-    public readonly parent: Logger | null = null,
+    public override readonly parent: Logger | null = null,
     public readonly levelCap: LogLevel,
   ) {
     super(name, parent, (level: LogLevel) => {

packages/angular_devkit/core/src/logger/logger.ts

@@ -134,22 +134,22 @@ export class Logger extends Observable<LogEntry> implements LoggerApi {
     return this.log('fatal', message, metadata);
   }
 
-  toString() {
+  override toString() {
     return `<Logger(${this.name})>`;
   }
 
-  lift<R>(operator: Operator<LogEntry, R>): Observable<R> {
+  override lift<R>(operator: Operator<LogEntry, R>): Observable<R> {
     return this._observable.lift(operator);
   }
 
-  subscribe(): Subscription;
+  override subscribe(): Subscription;
-  subscribe(observer: PartialObserver<LogEntry>): Subscription;
+  override subscribe(observer: PartialObserver<LogEntry>): Subscription;
-  subscribe(
+  override subscribe(
     next?: (value: LogEntry) => void,
     error?: (error: Error) => void,
     complete?: () => void,
   ): Subscription;
-  subscribe(
+  override subscribe(
     _observerOrNext?: PartialObserver<LogEntry> | ((value: LogEntry) => void),
     _error?: (error: Error) => void,
     _complete?: () => void,
@@ -158,10 +158,10 @@ export class Logger extends Observable<LogEntry> implements LoggerApi {
     return this._observable.subscribe.apply(
       this._observable,
       // eslint-disable-next-line prefer-rest-params
-      (arguments as unknown) as Parameters<Observable<LogEntry>['subscribe']>,
+      arguments as unknown as Parameters<Observable<LogEntry>['subscribe']>,
     );
   }
-  forEach(next: (value: LogEntry) => void, PromiseCtor?: typeof Promise): Promise<void> {
+  override forEach(next: (value: LogEntry) => void, PromiseCtor?: typeof Promise): Promise<void> {
     return this._observable.forEach(next, PromiseCtor);
   }
 }

packages/angular_devkit/core/src/logger/null-logger.ts

@@ -15,7 +15,7 @@ export class NullLogger extends Logger {
     this._observable = EMPTY;
   }
 
-  asApi(): LoggerApi {
+  override asApi(): LoggerApi {
     return {
       createChild: () => new NullLogger(this),
       log() {},

packages/angular_devkit/core/src/virtual-fs/host/record.ts

@@ -70,7 +70,7 @@ export class CordHost extends SimpleMemoryHost {
   get backend(): ReadonlyHost {
     return this._back;
   }
-  get capabilities(): HostCapabilities {
+  override get capabilities(): HostCapabilities {
     // Our own host is always Synchronous, but the backend might not be.
     return {
       synchronous: this._back.capabilities.synchronous,
@@ -219,7 +219,7 @@ export class CordHost extends SimpleMemoryHost {
     );
   }
 
-  write(path: Path, content: FileBuffer): Observable<void> {
+  override write(path: Path, content: FileBuffer): Observable<void> {
     return this.exists(path).pipe(
       switchMap((exists) => {
         if (exists) {
@@ -236,7 +236,7 @@ export class CordHost extends SimpleMemoryHost {
     );
   }
 
-  read(path: Path): Observable<FileBuffer> {
+  override read(path: Path): Observable<FileBuffer> {
     if (this._exists(path)) {
       return super.read(path);
     }
@@ -244,7 +244,7 @@ export class CordHost extends SimpleMemoryHost {
     return this._back.read(path);
   }
 
-  delete(path: Path): Observable<void> {
+  override delete(path: Path): Observable<void> {
     if (this._exists(path)) {
       if (this._filesToCreate.has(path)) {
         this._filesToCreate.delete(path);
@@ -280,7 +280,7 @@ export class CordHost extends SimpleMemoryHost {
     }
   }
 
-  rename(from: Path, to: Path): Observable<void> {
+  override rename(from: Path, to: Path): Observable<void> {
     return concat(this.exists(to), this.exists(from)).pipe(
       toArray(),
       switchMap(([existTo, existFrom]) => {
@@ -347,7 +347,7 @@ export class CordHost extends SimpleMemoryHost {
     );
   }
 
-  list(path: Path): Observable<PathFragment[]> {
+  override list(path: Path): Observable<PathFragment[]> {
     return concat(super.list(path), this._back.list(path)).pipe(
       reduce((list: Set<PathFragment>, curr: PathFragment[]) => {
         curr.forEach((elem) => list.add(elem));
@@ -358,17 +358,17 @@ export class CordHost extends SimpleMemoryHost {
     );
   }
 
-  exists(path: Path): Observable<boolean> {
+  override exists(path: Path): Observable<boolean> {
     return this._exists(path)
       ? of(true)
       : this.willDelete(path) || this.willRename(path)
       ? of(false)
       : this._back.exists(path);
   }
-  isDirectory(path: Path): Observable<boolean> {
+  override isDirectory(path: Path): Observable<boolean> {
     return this._exists(path) ? super.isDirectory(path) : this._back.isDirectory(path);
   }
-  isFile(path: Path): Observable<boolean> {
+  override isFile(path: Path): Observable<boolean> {
     return this._exists(path)
       ? super.isFile(path)
       : this.willDelete(path) || this.willRename(path)
@@ -376,7 +376,7 @@ export class CordHost extends SimpleMemoryHost {
       : this._back.isFile(path);
   }
 
-  stat(path: Path): Observable<Stats | null> | null {
+  override stat(path: Path): Observable<Stats | null> | null {
     return this._exists(path)
       ? super.stat(path)
       : this.willDelete(path) || this.willRename(path)
@@ -384,7 +384,7 @@ export class CordHost extends SimpleMemoryHost {
       : this._back.stat(path);
   }
 
-  watch(path: Path, options?: HostWatchOptions) {
+  override watch(path: Path, options?: HostWatchOptions) {
     // Watching not supported.
     return null;
   }

packages/angular_devkit/core/src/virtual-fs/host/test.ts

@@ -88,52 +88,52 @@ export namespace test {
     }
 
     // Override parents functions to keep a record of all operators that were done.
-    protected _write(path: Path, content: FileBuffer) {
+    protected override _write(path: Path, content: FileBuffer) {
       this._records.push({ kind: 'write', path });
 
       return super._write(path, content);
     }
-    protected _read(path: Path) {
+    protected override _read(path: Path) {
       this._records.push({ kind: 'read', path });
 
       return super._read(path);
     }
-    protected _delete(path: Path) {
+    protected override _delete(path: Path) {
       this._records.push({ kind: 'delete', path });
 
       return super._delete(path);
     }
-    protected _rename(from: Path, to: Path) {
+    protected override _rename(from: Path, to: Path) {
       this._records.push({ kind: 'rename', from, to });
 
       return super._rename(from, to);
     }
-    protected _list(path: Path): PathFragment[] {
+    protected override _list(path: Path): PathFragment[] {
       this._records.push({ kind: 'list', path });
 
       return super._list(path);
     }
-    protected _exists(path: Path) {
+    protected override _exists(path: Path) {
       this._records.push({ kind: 'exists', path });
 
       return super._exists(path);
     }
-    protected _isDirectory(path: Path) {
+    protected override _isDirectory(path: Path) {
       this._records.push({ kind: 'isDirectory', path });
 
       return super._isDirectory(path);
     }
-    protected _isFile(path: Path) {
+    protected override _isFile(path: Path) {
       this._records.push({ kind: 'isFile', path });
 
       return super._isFile(path);
     }
-    protected _stat(path: Path): Stats<SimpleMemoryHostStats> | null {
+    protected override _stat(path: Path): Stats<SimpleMemoryHostStats> | null {
       this._records.push({ kind: 'stat', path });
 
       return super._stat(path);
     }
-    protected _watch(path: Path, options?: HostWatchOptions): Observable<HostWatchEvent> {
+    protected override _watch(path: Path, options?: HostWatchOptions): Observable<HostWatchEvent> {
       this._records.push({ kind: 'watch', path });
 
       return super._watch(path, options);

packages/angular_devkit/core/src/workspace/definitions.ts

@@ -190,7 +190,7 @@ export class ProjectDefinitionCollection extends DefinitionCollection<ProjectDef
     return project;
   }
 
-  set(name: string, value: ProjectDefinition): this {
+  override set(name: string, value: ProjectDefinition): this {
     this._validateName(name);
 
     super.set(name, value);
@@ -235,7 +235,7 @@ export class TargetDefinitionCollection extends DefinitionCollection<TargetDefin
     return target;
   }
 
-  set(name: string, value: TargetDefinition): this {
+  override set(name: string, value: TargetDefinition): this {
     this._validateName(name);
 
     super.set(name, value);

packages/angular_devkit/schematics/src/sink/dryrun.ts

@@ -65,14 +65,14 @@ export class DryRunSink extends HostSink {
     );
   }
 
-  protected _fileAlreadyExistException(path: string): void {
+  protected override _fileAlreadyExistException(path: string): void {
     this._fileAlreadyExistExceptionSet.add(path);
   }
-  protected _fileDoesNotExistException(path: string): void {
+  protected override _fileDoesNotExistException(path: string): void {
     this._fileDoesNotExistExceptionSet.add(path);
   }
 
-  _done() {
+  override _done() {
     this._fileAlreadyExistExceptionSet.forEach((path) => {
       this._subject.next({
         kind: 'error',

packages/angular_devkit/schematics/src/sink/host.ts

@@ -29,7 +29,7 @@ export class HostSink extends SimpleSinkBase {
     super();
   }
 
-  protected _validateCreateAction(action: CreateFileAction): Observable<void> {
+  protected override _validateCreateAction(action: CreateFileAction): Observable<void> {
     return this._force ? EMPTY : super._validateCreateAction(action);
   }
 

packages/angular_devkit/schematics/src/tree/recorder.ts

@@ -75,15 +75,15 @@ export class UpdateRecorderBom extends UpdateRecorderBase {
     super(entry);
   }
 
-  insertLeft(index: number, content: Buffer | string) {
+  override insertLeft(index: number, content: Buffer | string) {
     return super.insertLeft(index + this._delta, content);
   }
 
-  insertRight(index: number, content: Buffer | string) {
+  override insertRight(index: number, content: Buffer | string) {
     return super.insertRight(index + this._delta, content);
   }
 
-  remove(index: number, length: number) {
+  override remove(index: number, length: number) {
     return super.remove(index + this._delta, length);
   }
 }

packages/angular_devkit/schematics/src/tree/scoped.ts

@@ -101,7 +101,7 @@ export class ScopedTree implements Tree {
     // eslint-disable-next-line @typescript-eslint/no-this-alias
     const self = this;
     const delegate = new (class extends DelegateTree {
-      get actions(): Action[] {
+      override get actions(): Action[] {
         return other.actions.map((action) => self._fullPathAction(action));
       }
     })(other);

packages/angular_devkit/schematics/tools/file-system-engine-host.ts

@@ -85,7 +85,7 @@ export class FileSystemEngineHost extends FileSystemEngineHostBase {
     return desc as FileSystemSchematicDesc;
   }
 
-  hasTaskExecutor(name: string): boolean {
+  override hasTaskExecutor(name: string): boolean {
     if (super.hasTaskExecutor(name)) {
       return true;
     }
@@ -100,7 +100,7 @@ export class FileSystemEngineHost extends FileSystemEngineHostBase {
     return false;
   }
 
-  createTaskExecutor(name: string): Observable<TaskExecutor> {
+  override createTaskExecutor(name: string): Observable<TaskExecutor> {
     if (!super.hasTaskExecutor(name)) {
       try {
         const path = require.resolve(join(this._root, name));

packages/angular_devkit/schematics/tools/node-modules-test-engine-host.ts

@@ -30,7 +30,7 @@ export class NodeModulesTestEngineHost extends NodeModulesEngineHost {
     this._collections.set(name, path);
   }
 
-  transformContext(context: FileSystemSchematicContext): FileSystemSchematicContext {
+  override transformContext(context: FileSystemSchematicContext): FileSystemSchematicContext {
     const oldAddTask = context.addTask;
     context.addTask = (task: TaskConfigurationGenerator<{}>, dependencies?: Array<TaskId>) => {
       this._tasks.push(task.toConfiguration());
@@ -41,7 +41,7 @@ export class NodeModulesTestEngineHost extends NodeModulesEngineHost {
     return context;
   }
 
-  protected _resolveCollectionPath(name: string, requester?: string): string {
+  protected override _resolveCollectionPath(name: string, requester?: string): string {
     const maybePath = this._collections.get(name);
     if (maybePath) {
       return maybePath;

packages/angular_devkit/schematics/tools/workflow/node-workflow.ts

@@ -84,10 +84,10 @@ export class NodeWorkflow extends workflow.BaseWorkflow {
     this._context = [];
   }
 
-  get engine(): FileSystemEngine {
+  override get engine(): FileSystemEngine {
     return this._engine as FileSystemEngine;
   }
-  get engineHost(): NodeModulesEngineHost {
+  override get engineHost(): NodeModulesEngineHost {
     return this._engineHost as NodeModulesEngineHost;
   }
 }

tsconfig.json

@@ -6,6 +6,7 @@
     "moduleResolution": "node",
     "noEmitOnError": true,
     "noFallthroughCasesInSwitch": true,
+    "noImplicitOverride": true,
     "noUnusedParameters": false,
     "noUnusedLocals": false,
     "outDir": "./dist",