fix(@angular/build): capture and report Rolldown warnings and errors in library builder

Updates `bundleEntryPoints` to capture Rolldown warning logs via `onLog` and bundling errors, returning them to `buildAction` so warnings are logged via the builder logger instead of `console.warn` and errors are properly surfaced.

Author: alan-agius4

packages/angular/build/src/builders/library/pipeline/build-action.ts

@@ -152,14 +152,18 @@ export async function buildAction(actionContext: BuildActionContext): Promise<vo
       throw error;
     }
 
+    for (const warning of [...warnings, ...bundleOutput.warnings]) {
+      context.logger.warn(warning);
+    }
+
+    if (bundleOutput.errors.length > 0) {
+      throw new Error(bundleOutput.errors.join('\n'));
+    }
+
     buildState.hasCompilationError = false;
     pendingChangedEsmFiles.clear();
     pendingChangedDtsFiles.clear();
 
-    for (const warning of warnings) {
-      context.logger.warn(warning);
-    }
-
     filesToEmit.push(...bundleOutput.filesToEmit);
     for (const [name, bundleResult] of bundleOutput.bundleResults) {
       buildState.previousBundleResults.set(name, bundleResult);

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

@@ -34,6 +34,12 @@ export interface BundleEntryPointsOutput {
 
   /** Map of entry point names to their bundle results containing bundled module IDs. */
   bundleResults: Map<string, BundleResult>;
+
+  /** Warning messages emitted during bundling. */
+  warnings: string[];
+
+  /** Error messages emitted during bundling. */
+  errors: string[];
 }
 
 /**
@@ -65,6 +71,12 @@ interface MultiBundleOutput {
 
   /** Map of bundle entry names to the set of virtual module IDs included in the bundle. */
   moduleIdsByBundle: Map<string, Set<string>>;
+
+  /** Warning messages emitted during the bundle invocation. */
+  warnings: string[];
+
+  /** Error messages emitted during the bundle invocation. */
+  errors: string[];
 }
 
 /**
@@ -85,7 +97,7 @@ export async function bundleEntryPoints(
 ): Promise<BundleEntryPointsOutput> {
   const bundleResults = new Map<string, BundleResult>();
   if (items.length === 0) {
-    return { filesToEmit: [], bundleResults };
+    return { filesToEmit: [], bundleResults, warnings: [], errors: [] };
   }
 
   const esmEntryPoints: NormalizedEntryPoint[] = [];
@@ -122,6 +134,8 @@ export async function bundleEntryPoints(
   return {
     filesToEmit: [...esmOutput.filesToEmit, ...dtsOutput.filesToEmit],
     bundleResults,
+    warnings: [...esmOutput.warnings, ...dtsOutput.warnings],
+    errors: [...esmOutput.errors, ...dtsOutput.errors],
   };
 }
 
@@ -228,7 +242,10 @@ function createMemoryFileLoaderPlugin(
  * @param dir The destination output directory prefix.
  * @returns The processed multi-bundle output.
  */
-function processRolldownOutput(output: RolldownOutput['output'], dir: string): MultiBundleOutput {
+function processRolldownOutput(
+  output: RolldownOutput['output'],
+  dir: string,
+): Pick<MultiBundleOutput, 'filesToEmit' | 'moduleIdsByBundle'> {
   const filesToEmit: MemoryOutputFile[] = [];
   const moduleIdsByBundle = new Map<string, Set<string>>();
   const chunksByFileName = new Map<string, OutputChunk>();
@@ -295,7 +312,6 @@ function processRolldownOutput(output: RolldownOutput['output'], dir: string): M
  * @param preserveSymlinks Whether to preserve symlinks during module resolution.
  * @param extension Output file extension ('mjs' or 'd.ts').
  * @param sourcemap Whether to emit sourcemaps.
- * @param findEntryPoint Lookup function to resolve chunk entry point ownership.
  * @returns A promise resolving to the multi-bundle output.
  */
 async function executeMultiBundle(
@@ -307,19 +323,28 @@ async function executeMultiBundle(
 ): Promise<MultiBundleOutput> {
   const isDts = extension === 'd.ts';
   const dir = isDts ? TYPES_OUTPUT_DIR : FESM_OUTPUT_DIR;
-  const bundle = await rolldown({
-    context: 'this',
-    input,
-    plugins,
-    treeshake: false,
-    resolve: { symlinks: !preserveSymlinks },
-    checks: { circularDependency: false },
-    experimental: {
-      attachDebugInfo: 'none',
-    },
-  });
+  const warnings: string[] = [];
+  const errors: string[] = [];
+  let bundle: Awaited<ReturnType<typeof rolldown>> | undefined;
 
   try {
+    bundle = await rolldown({
+      context: 'this',
+      input,
+      plugins,
+      treeshake: false,
+      resolve: { symlinks: !preserveSymlinks },
+      checks: { circularDependency: false },
+      onLog(level, log) {
+        if (level === 'warn') {
+          warnings.push(log.message);
+        }
+      },
+      experimental: {
+        attachDebugInfo: 'none',
+      },
+    });
+
     const { output } = await bundle.generate({
       format: 'es',
       dir,
@@ -330,9 +355,25 @@ async function executeMultiBundle(
       comments: { jsdoc: isDts, legal: true, annotation: true },
     });
 
-    return processRolldownOutput(output, dir);
+    const { filesToEmit, moduleIdsByBundle } = processRolldownOutput(output, dir);
+
+    return {
+      filesToEmit,
+      moduleIdsByBundle,
+      warnings,
+      errors,
+    };
+  } catch (error) {
+    errors.push(error instanceof Error ? error.message : String(error));
+
+    return {
+      filesToEmit: [],
+      moduleIdsByBundle: new Map(),
+      warnings,
+      errors,
+    };
   } finally {
-    await bundle.close();
+    await bundle?.close();
   }
 }
 
@@ -350,7 +391,7 @@ async function bundleAllEsm(
   options: NormalizedLibraryOptions,
 ): Promise<MultiBundleOutput> {
   if (entryPoints.length === 0) {
-    return { filesToEmit: [], moduleIdsByBundle: new Map() };
+    return { filesToEmit: [], moduleIdsByBundle: new Map(), warnings: [], errors: [] };
   }
 
   return executeMultiBundle(
@@ -376,7 +417,7 @@ async function bundleAllDts(
   options: NormalizedLibraryOptions,
 ): Promise<MultiBundleOutput> {
   if (entryPoints.length === 0) {
-    return { filesToEmit: [], moduleIdsByBundle: new Map() };
+    return { filesToEmit: [], moduleIdsByBundle: new Map(), warnings: [], errors: [] };
   }
 
   const dtsSourcemap = options.declarationMap;

packages/angular/build/src/builders/library/tests/behavior/build_spec.ts

@@ -47,5 +47,25 @@ describeLibraryBuilder(executeLibraryBuilder, LIBRARY_BUILDER_INFO, (harness) =>
         }),
       );
     });
+
+    it('should log Rolldown bundler warnings', async () => {
+      await harness.writeFile(
+        'projects/lib/src/public-api.ts',
+        `export function runDynamic(code: string) { return eval(code); }`,
+      );
+
+      harness.useTarget('build', {
+        ...BASE_OPTIONS,
+      });
+
+      const { result, logs } = await harness.executeOnce();
+      expect(result?.success).toBeTrue();
+      expect(logs).toContain(
+        jasmine.objectContaining({
+          level: 'warn',
+          message: jasmine.stringContaining('eval'),
+        }),
+      );
+    });
   });
 });