fixup! fix(@angular/build): improve library compilation diagnostics and skip redundant d.ts rebundling

Author: alan-agius4

packages/angular/build/src/builders/library/pipeline/compilation.ts

@@ -11,6 +11,7 @@ import { existsSync } from 'node:fs';
 import {
   type AngularCompilation,
   DiagnosticModes,
+  type EmitFileResult,
   createAngularCompilation,
 } from '../../../tools/angular/compilation';
 import type { ComponentStylesheetBundler } from '../../../tools/esbuild/angular/component-stylesheets';
@@ -79,6 +80,9 @@ export async function compileLibrary(
     const failedFiles = new Set<string>();
     const clearedReferenceFiles = new Set<string>();
     const clearPreviousReferencesOnce = (targetFile: string): void => {
+      if (!cached) {
+        return;
+      }
       const posixTarget = toPosixPath(targetFile);
       if (!clearedReferenceFiles.has(posixTarget)) {
         clearedReferenceFiles.add(posixTarget);
@@ -167,51 +171,14 @@ export async function compileLibrary(
 
     const esmFiles = cached?.esmFiles ?? new Map<string, string>();
     const dtsFiles = cached?.dtsFiles ?? new Map<string, string>();
-    const changedEsmFiles = new Set<string>();
-    const changedDtsFiles = new Set<string>();
     const posixReferencedFiles = new Set(referencedFiles.map(toPosixPath));
-
-    if (cached && effectiveModifiedFiles) {
-      for (const modifiedFile of effectiveModifiedFiles) {
-        if (posixReferencedFiles.has(modifiedFile)) {
-          continue;
-        }
-
-        const basePathWithoutExt = modifiedFile.replace(/(?:\.d\.[cm]?ts|\.[cm]?[jt]sx?)$/i, '');
-        if (basePathWithoutExt === modifiedFile || existsSync(modifiedFile)) {
-          continue;
-        }
-
-        for (const ext of EMITTED_EXTENSIONS) {
-          const outputPath = `${basePathWithoutExt}${ext}`;
-          const mapPath = `${outputPath}.map`;
-          if (esmFiles.delete(outputPath)) {
-            changedEsmFiles.add(outputPath);
-          }
-          if (dtsFiles.delete(outputPath)) {
-            changedDtsFiles.add(outputPath);
-          }
-          esmFiles.delete(mapPath);
-          dtsFiles.delete(mapPath);
-        }
-      }
-    }
-
-    for (const { filename, contents } of emittedFiles) {
-      const normalized = toPosixPath(filename);
-      const isMap = normalized.endsWith('.map');
-      const isDts = isMap ? isDeclarationSourceMapFile(normalized) : isDeclarationFile(normalized);
-      const targetFiles = isDts ? dtsFiles : esmFiles;
-
-      if (targetFiles.get(normalized) !== contents) {
-        targetFiles.set(normalized, contents);
-        if (!isDts) {
-          changedEsmFiles.add(isMap ? normalized.slice(0, -4) : normalized);
-        } else if (!isMap) {
-          changedDtsFiles.add(normalized);
-        }
-      }
-    }
+    const { changedEsmFiles, changedDtsFiles } = updateEmittedFileCaches(
+      emittedFiles,
+      esmFiles,
+      dtsFiles,
+      posixReferencedFiles,
+      cached ? effectiveModifiedFiles : undefined,
+    );
 
     const diagnosePromise = runDiagnosticsAndFormat(
       compilationInstance,
@@ -246,6 +213,72 @@ export async function compileLibrary(
   }
 }
 
+/**
+ * Updates the in-memory ESM and DTS file maps with newly emitted files and prunes deleted
+ * source files, returning the sets of changed ESM and DTS file paths.
+ *
+ * @param emittedFiles Newly emitted files from the Angular compilation.
+ * @param esmFiles In-memory map of POSIX ESM file paths to contents.
+ * @param dtsFiles In-memory map of POSIX declaration file paths to contents.
+ * @param posixReferencedFiles Set of POSIX file paths currently referenced by the program.
+ * @param modifiedFiles Optional set of modified POSIX file paths in incremental builds.
+ * @returns Sets of changed ESM and DTS file paths.
+ */
+function updateEmittedFileCaches(
+  emittedFiles: Iterable<EmitFileResult>,
+  esmFiles: Map<string, string>,
+  dtsFiles: Map<string, string>,
+  posixReferencedFiles: ReadonlySet<string>,
+  modifiedFiles?: ReadonlySet<string>,
+): { changedEsmFiles: Set<string>; changedDtsFiles: Set<string> } {
+  const changedEsmFiles = new Set<string>();
+  const changedDtsFiles = new Set<string>();
+
+  if (modifiedFiles) {
+    for (const modifiedFile of modifiedFiles) {
+      if (posixReferencedFiles.has(modifiedFile)) {
+        continue;
+      }
+
+      const basePathWithoutExt = modifiedFile.replace(/(?:\.d\.[cm]?ts|\.[cm]?[jt]sx?)$/i, '');
+      if (basePathWithoutExt === modifiedFile || existsSync(modifiedFile)) {
+        continue;
+      }
+
+      for (const ext of EMITTED_EXTENSIONS) {
+        const outputPath = `${basePathWithoutExt}${ext}`;
+        const mapPath = `${outputPath}.map`;
+        if (esmFiles.delete(outputPath)) {
+          changedEsmFiles.add(outputPath);
+        }
+        if (dtsFiles.delete(outputPath)) {
+          changedDtsFiles.add(outputPath);
+        }
+        esmFiles.delete(mapPath);
+        dtsFiles.delete(mapPath);
+      }
+    }
+  }
+
+  for (const { filename, contents } of emittedFiles) {
+    const normalized = toPosixPath(filename);
+    const isMap = normalized.endsWith('.map');
+    const isDts = isMap ? isDeclarationSourceMapFile(normalized) : isDeclarationFile(normalized);
+    const targetFiles = isDts ? dtsFiles : esmFiles;
+
+    if (targetFiles.get(normalized) !== contents) {
+      targetFiles.set(normalized, contents);
+      if (!isDts) {
+        changedEsmFiles.add(isMap ? normalized.slice(0, -4) : normalized);
+      } else if (!isMap) {
+        changedDtsFiles.add(normalized);
+      }
+    }
+  }
+
+  return { changedEsmFiles, changedDtsFiles };
+}
+
 /**
  * Formats stylesheet bundling diagnostics and TypeScript/Angular diagnostics
  * and records them on the build state's execution result.

packages/angular/build/src/builders/library/pipeline/compilation_spec.ts

@@ -169,7 +169,7 @@ describe('compileLibrary pipeline', () => {
     expect(warningsText).toContain('NG8107: Optional chain warning');
   });
 
-  it('should still run diagnoseFiles when stylesheetErrors are present and handle diagnoseFiles rejection without unhandled rejection', async () => {
+  it('should run diagnoseFiles when stylesheetErrors are present and catch diagnoseFiles rejections', async () => {
     const compilationInstance: AngularCompilation = {
       initialize: jasmine
         .createSpy('initialize')