fix(@angular-devkit/build-angular): better handle Windows paths in esbuild experimental builder

packages/angular_devkit/build_angular/src/builders/browser-esbuild/esbuild.ts

@@ -16,6 +16,10 @@ import {
   build,
   formatMessages,
 } from 'esbuild';
+import { resolve } from 'path';
+
+/** Default outdir setting for esbuild. */
+export const DEFAULT_OUTDIR = resolve('/virtual-output');
 
 /**
  * Determines if an unknown value is an esbuild BuildFailure error object thrown by esbuild.

packages/angular_devkit/build_angular/src/builders/browser-esbuild/index.ts

@@ -20,7 +20,7 @@ import { getIndexInputFile, getIndexOutputFile } from '../../utils/webpack-brows
 import { resolveGlobalStyles } from '../../webpack/configs';
 import { Schema as BrowserBuilderOptions, SourceMapClass } from '../browser/schema';
 import { createCompilerPlugin } from './compiler-plugin';
-import { bundle, logMessages } from './esbuild';
+import { DEFAULT_OUTDIR, bundle, logMessages } from './esbuild';
 import { logExperimentalWarnings } from './experimental-warnings';
 import { normalizeOptions } from './options';
 import { bundleStylesheetText } from './stylesheets';
@@ -116,11 +116,13 @@ export async function execute(
     // Entries in the metafile are relative to the `absWorkingDir` option which is set to the workspaceRoot
     const relativeFilePath = path.relative(workspaceRoot, outputFile.path);
     const entryPoint = result.metafile?.outputs[relativeFilePath]?.entryPoint;
+
+    outputFile.path = path.relative(DEFAULT_OUTDIR, outputFile.path);
+
     if (entryPoint) {
       // An entryPoint value indicates an initial file
       initialFiles.push({
-        // Remove leading directory separator
-        file: outputFile.path.slice(1),
+        file: outputFile.path,
         name: entryPointNameLookup.get(entryPoint) ?? '',
         extension: path.extname(outputFile.path),
       });
@@ -147,7 +149,9 @@ export async function execute(
       !!options.preserveSymlinks,
     );
     for (const [name, files] of Object.entries(stylesheetEntrypoints)) {
-      const virtualEntryData = files.map((file) => `@import '${file}';`).join('\n');
+      const virtualEntryData = files
+        .map((file) => `@import '${file.replace(/\\/g, '/')}';`)
+        .join('\n');
       const sheetResult = await bundleStylesheetText(
         virtualEntryData,
         { virtualName: `angular:style/global;${name}`, resolvePath: workspaceRoot },
@@ -172,7 +176,7 @@ export async function execute(
       // The virtual stylesheets will be named `stdin` by esbuild. This must be replaced
       // with the actual name of the global style and the leading directory separator must
       // also be removed to make the path relative.
-      const sheetPath = sheetResult.path.replace('stdin', name).slice(1);
+      const sheetPath = sheetResult.path.replace('stdin', name);
       outputFiles.push(createOutputFileFromText(sheetPath, sheetResult.contents));
       if (sheetResult.map) {
         outputFiles.push(createOutputFileFromText(sheetPath + '.map', sheetResult.map));
@@ -203,10 +207,13 @@ export async function execute(
       optimization: optimizationOptions,
       crossOrigin: options.crossOrigin,
     });
-    indexHtmlGenerator.readAsset = async function (path: string): Promise<string> {
+
+    /** Virtual output path to support reading in-memory files. */
+    const virtualOutputPath = '/';
+    indexHtmlGenerator.readAsset = async function (filePath: string): Promise<string> {
       // Remove leading directory separator
-      path = path.slice(1);
-      const file = outputFiles.find((file) => file.path === path);
+      const relativefilePath = path.relative(virtualOutputPath, filePath);
+      const file = outputFiles.find((file) => file.path === relativefilePath);
       if (file) {
         return file.text;
       }
@@ -217,7 +224,7 @@ export async function execute(
     const { content, warnings, errors } = await indexHtmlGenerator.process({
       baseHref: options.baseHref,
       lang: undefined,
-      outputPath: '/', // Virtual output path to support reading in-memory files
+      outputPath: virtualOutputPath,
       files: initialFiles,
     });
 
@@ -280,7 +287,7 @@ async function bundleCode(
     metafile: true,
     minify: optimizationOptions.scripts,
     pure: ['forwardRef'],
-    outdir: '/',
+    outdir: DEFAULT_OUTDIR,
     sourcemap: sourcemapOptions.scripts && (sourcemapOptions.hidden ? 'external' : true),
     splitting: true,
     tsconfig,

packages/angular_devkit/build_angular/src/builders/browser-esbuild/stylesheets.ts

@@ -8,7 +8,7 @@
 
 import type { BuildOptions, OutputFile } from 'esbuild';
 import * as path from 'path';
-import { bundle } from './esbuild';
+import { DEFAULT_OUTDIR, bundle } from './esbuild';
 
 export interface BundleStylesheetOptions {
   workspaceRoot?: string;
@@ -32,7 +32,7 @@ async function bundleStylesheet(
     logLevel: 'silent',
     minify: options.optimization,
     sourcemap: options.sourcemap,
-    outdir: '/',
+    outdir: DEFAULT_OUTDIR,
     write: false,
     platform: 'browser',
     preserveSymlinks: options.preserveSymlinks,
@@ -50,6 +50,7 @@ async function bundleStylesheet(
   const resourceFiles: OutputFile[] = [];
   if (result.outputFiles) {
     for (const outputFile of result.outputFiles) {
+      outputFile.path = path.relative(DEFAULT_OUTDIR, outputFile.path);
       const filename = path.basename(outputFile.path);
       if (filename.endsWith('.css')) {
         outputPath = outputFile.path;