perf(@angular/build): optimize incremental watch rebuilds in AOT compilation

- Pre-populate `.d.ts` shape signatures on the previous `BuilderProgram` for modified files prior to diffing when type-checking or TypeScript transpilation is active, preventing false-positive `.d.ts` cascades on incremental watch edits.
- Synchronize `typeScriptProgram` with `angularCompiler.getCurrentProgram()` after `collectDiagnostics()` and clear uncommitted `changedFilesSet` and `oldSignatures` entries so subsequent incremental builds preserve `.d.ts` signatures and do not treat `.ngtypecheck.ts` shims as newly added files.
- Detect affected dependent `.ngtypecheck.ts` shims in `isolatedModules` / `verbatimModuleSyntax` mode via TypeScript's `state.hasCalledUpdateShapeSignature`, ensuring cross-component template diagnostics are re-evaluated when a dependency's `.d.ts` shape changes without cascading on private edits.
- Avoid `filter().flatMap()` allocations and skip `getResourceDependencies()` for declaration files when collecting `referencedFiles`.

Author: alan-agius4

packages/angular/build/src/builders/application/tests/behavior/rebuild-errors_spec.ts

@@ -15,12 +15,6 @@ import {
   expectNoLog,
 } from '../setup';
 
-/**
- * Maximum time in milliseconds for single build/rebuild
- * This accounts for CI variability.
- */
-export const BUILD_TIMEOUT = 30_000;
-
 describeBuilder(buildApplication, APPLICATION_BUILDER_INFO, (harness) => {
   describe('Behavior: "Rebuild Error Detection"', () => {
     it('detects template errors with no AOT codegen or TS emit differences', async () => {
@@ -128,6 +122,235 @@ describeBuilder(buildApplication, APPLICATION_BUILDER_INFO, (harness) => {
       );
     });
 
+    it('detects template errors across components on watch rebuild when isolatedModules is enabled', async () => {
+      harness.useTarget('build', {
+        ...BASE_OPTIONS,
+        watch: true,
+      });
+
+      await harness.modifyFile('tsconfig.json', (content) => {
+        const tsconfig = JSON.parse(content);
+        tsconfig.compilerOptions = {
+          ...tsconfig.compilerOptions,
+          isolatedModules: true,
+        };
+
+        return JSON.stringify(tsconfig);
+      });
+
+      const goodChildComponentContents = `
+        import { Component, Input } from '@angular/core';
+        @Component({
+          selector: 'child',
+          standalone: true,
+          template: '<p>{{ value }}</p>',
+        })
+        export class ChildComponent {
+          @Input() value!: number;
+        }
+      `;
+
+      const typeErrorText = `Type 'number' is not assignable to type 'string'.`;
+
+      await harness.writeFiles({
+        'src/app/child.component.ts': goodChildComponentContents,
+        'src/app/app.module.ts': `
+          import { NgModule } from '@angular/core';
+          import { BrowserModule } from '@angular/platform-browser';
+          import { AppComponent } from './app.component';
+          @NgModule({
+            imports: [
+              BrowserModule,
+              AppComponent,
+            ],
+            providers: [],
+            bootstrap: [AppComponent]
+          })
+          export class AppModule { }
+        `,
+        'src/app/app.component.ts': `
+          import { Component } from '@angular/core';
+          import { ChildComponent } from './child.component';
+          @Component({
+            selector: 'app-root',
+            standalone: true,
+            imports: [ChildComponent],
+            template: '<child [value]="123" />',
+          })
+          export class AppComponent {}
+        `,
+      });
+
+      await harness.executeWithCases(
+        [
+          async ({ result }) => {
+            expect(result?.success).toBeTrue();
+
+            // Update child component to change input type from number to string
+            await harness.writeFile(
+              'src/app/child.component.ts',
+              `
+              import { Component, Input } from '@angular/core';
+              @Component({
+                selector: 'child',
+                standalone: true,
+                template: '<p>{{ value }}</p>',
+              })
+              export class ChildComponent {
+                @Input() value!: string;
+              }
+            `,
+            );
+          },
+          async ({ result, logs }) => {
+            expect(result?.success).toBeFalse();
+            expectLog(logs, typeErrorText);
+
+            // Make an unrelated change to verify error persists
+            await harness.modifyFile('src/main.ts', (content) => content + '\n');
+          },
+          async ({ result, logs }) => {
+            expect(result?.success).toBeFalse();
+            expectLog(logs, typeErrorText);
+
+            // Revert back to number
+            await harness.writeFile('src/app/child.component.ts', goodChildComponentContents);
+          },
+          async ({ result, logs }) => {
+            expect(result?.success).toBeTrue();
+            expectNoLog(logs, typeErrorText);
+
+            // Make an unrelated change to verify error cache cleared
+            await harness.modifyFile('src/main.ts', (content) => content + '\n');
+          },
+          ({ result, logs }) => {
+            expect(result?.success).toBeTrue();
+            expectNoLog(logs, typeErrorText);
+          },
+        ],
+        { outputLogsOnFailure: false },
+      );
+    });
+
+    it('detects template errors when an input becomes required or a selector is renamed on watch rebuild', async () => {
+      harness.useTarget('build', {
+        ...BASE_OPTIONS,
+        watch: true,
+      });
+
+      await harness.modifyFile('tsconfig.json', (content) => {
+        const tsconfig = JSON.parse(content);
+        tsconfig.compilerOptions = {
+          ...tsconfig.compilerOptions,
+          isolatedModules: true,
+        };
+
+        return JSON.stringify(tsconfig);
+      });
+
+      const goodChildComponentContents = `
+        import { Component, input } from '@angular/core';
+        @Component({
+          selector: 'app-child',
+          standalone: true,
+          template: '<p>{{ label() }}</p>',
+        })
+        export class ChildComponent {
+          label = input('');
+        }
+      `;
+
+      const requiredInputErrorText = `Required input 'label' from component ChildComponent must be specified.`;
+      const unknownElementErrorText = `'app-child' is not a known element`;
+
+      await harness.writeFiles({
+        'src/app/child.component.ts': goodChildComponentContents,
+        'src/app/app.module.ts': `
+          import { NgModule } from '@angular/core';
+          import { BrowserModule } from '@angular/platform-browser';
+          import { AppComponent } from './app.component';
+          @NgModule({
+            imports: [
+              BrowserModule,
+              AppComponent,
+            ],
+            providers: [],
+            bootstrap: [AppComponent]
+          })
+          export class AppModule { }
+        `,
+        'src/app/app.component.ts': `
+          import { Component } from '@angular/core';
+          import { ChildComponent } from './child.component';
+          @Component({
+            selector: 'app-root',
+            standalone: true,
+            imports: [ChildComponent],
+            template: '<app-child />',
+          })
+          export class AppComponent {}
+        `,
+      });
+
+      await harness.executeWithCases(
+        [
+          async ({ result }) => {
+            expect(result?.success).toBeTrue();
+
+            // Make input required using signal input.required() (which has the same TS .d.ts type InputSignal<string>)
+            await harness.writeFile(
+              'src/app/child.component.ts',
+              `
+              import { Component, input } from '@angular/core';
+              @Component({
+                selector: 'app-child',
+                standalone: true,
+                template: '<p>{{ label() }}</p>',
+              })
+              export class ChildComponent {
+                label = input.required<string>();
+              }
+            `,
+            );
+          },
+          async ({ result, logs }) => {
+            expect(result?.success).toBeFalse();
+            expectLog(logs, requiredInputErrorText);
+
+            // Revert required input and rename selector instead
+            await harness.writeFile(
+              'src/app/child.component.ts',
+              `
+              import { Component, input } from '@angular/core';
+              @Component({
+                selector: 'app-child-renamed',
+                standalone: true,
+                template: '<p>{{ label() }}</p>',
+              })
+              export class ChildComponent {
+                label = input('');
+              }
+            `,
+            );
+          },
+          async ({ result, logs }) => {
+            expect(result?.success).toBeFalse();
+            expectNoLog(logs, requiredInputErrorText);
+            expectLog(logs, unknownElementErrorText);
+
+            // Revert back to valid child component
+            await harness.writeFile('src/app/child.component.ts', goodChildComponentContents);
+          },
+          ({ result, logs }) => {
+            expect(result?.success).toBeTrue();
+            expectNoLog(logs, requiredInputErrorText);
+            expectNoLog(logs, unknownElementErrorText);
+          },
+        ],
+        { outputLogsOnFailure: false },
+      );
+    });
+
     it('detects cumulative block syntax errors', async () => {
       harness.useTarget('build', {
         ...BASE_OPTIONS,
@@ -234,7 +457,7 @@ describeBuilder(buildApplication, APPLICATION_BUILDER_INFO, (harness) => {
             await harness.appendToFile('src/app/app.component.html', '<div>Guten Tag</div>');
           },
           ({ logs }) => {
-            expectNoLog(logs, 'invalid-css-content');
+            expectNoLog(logs, 'Unexpected character "EOF"');
 
             harness.expectFile('dist/browser/main.js').content.toContain('Hello, world!');
             harness.expectFile('dist/browser/main.js').content.toContain('Guten Tag');

packages/angular/build/src/tools/angular/angular-host.ts

@@ -35,7 +35,10 @@ export interface AngularHostOptions {
  * field. The `version` field is required when used with a TypeScript BuilderProgram.
  * @param program The TypeScript Program instance to patch.
  */
-export function ensureSourceFileVersions(program: ts.Program): void {
+export function ensureSourceFileVersions(
+  program: ts.Program,
+  previousProgram?: ts.BuilderProgram,
+): void {
   const baseGetSourceFiles = program.getSourceFiles;
   // TODO: Update Angular compiler to add versions to all internal files and remove this
   program.getSourceFiles = function (...parameters) {
@@ -45,7 +48,11 @@ export function ensureSourceFileVersions(program: ts.Program): void {
 
     for (const file of files) {
       if (file.version === undefined) {
-        file.version = calculateHash(file.text);
+        const previousFile: (ts.SourceFile & { version?: string }) | undefined =
+          previousProgram && !file.fileName.endsWith('.ngtypecheck.ts')
+            ? previousProgram.getSourceFile(file.fileName)
+            : undefined;
+        file.version = previousFile?.version ?? calculateHash(file.text);
       }
     }