fix(@angular-devkit/build-angular): allow emitting multiple files with the same filename

Previously when hashing of media was disabled, if 2 files had the same name. Only one files used to be emitted. With this change we change the behaviour so that both files are emitted.

Closes #12186

packages/angular_devkit/build_angular/src/webpack/configs/common.ts

@@ -249,7 +249,7 @@ export function getCommonConfig(wco: WebpackConfigOptions): Configuration {
     return prev;
   }, []);
 
-    // Add a new asset for each entry.
+  // Add a new asset for each entry.
   for (const script of globalScriptsByBundleName) {
     // Lazy scripts don't get a hash, otherwise they can't be loaded by name.
     const hash = script.inject ? hashFormat.script : '';

packages/angular_devkit/build_angular/src/webpack/configs/styles.ts

@@ -17,7 +17,7 @@ import {
   RemoveHashPlugin,
   SuppressExtractedTextChunksWebpackPlugin,
 } from '../plugins';
-import { getOutputHashFormat, normalizeExtraEntryPoints } from '../utils/helpers';
+import { assetNameTemplateFactory, getOutputHashFormat, normalizeExtraEntryPoints } from '../utils/helpers';
 
 // tslint:disable-next-line:no-big-function
 export function getStylesConfig(wco: WebpackConfigOptions) {
@@ -154,6 +154,8 @@ export function getStylesConfig(wco: WebpackConfigOptions) {
     },
   ];
 
+  const assetNameTemplate = assetNameTemplateFactory(hashFormat);
+
   const postcssOptionsCreator = (sourceMap: boolean, extracted: boolean | undefined) => {
     return (loader: webpack.loader.LoaderContext) => ({
       map: sourceMap && {
@@ -183,7 +185,7 @@ export function getStylesConfig(wco: WebpackConfigOptions) {
           deployUrl: buildOptions.deployUrl,
           resourcesOutputPath: buildOptions.resourcesOutputPath,
           loader,
-          filename: `[name]${hashFormat.file}.[ext]`,
+          filename: assetNameTemplate,
           emitFile: buildOptions.platform !== 'server',
           extracted,
         }),

packages/angular_devkit/build_angular/src/webpack/plugins/postcss-cli-resources.ts

@@ -31,7 +31,7 @@ export interface PostcssCliResourcesOptions {
   rebaseRootRelative?: boolean;
   /** CSS is extracted to a `.css` or is embedded in a `.js` file. */
   extracted?: boolean;
-  filename: string;
+  filename: (resourcePath: string) => string;
   loader: webpack.loader.LoaderContext;
   emitFile: boolean;
 }
@@ -113,10 +113,11 @@ export default function(options?: PostcssCliResourcesOptions): Plugin {
         }
 
         let outputPath = interpolateName(
-          { resourcePath: result } as webpack.loader.LoaderContext,
-          filename,
-          { content },
-        );
+          {  resourcePath: result } as webpack.loader.LoaderContext,
+          filename(result),
+          { content, context: loader.context || loader.rootContext },
+        )
+        .replace(/\\|\//g, '-');
 
         if (resourcesOutputPath) {
           outputPath = path.posix.join(resourcesOutputPath, outputPath);

packages/angular_devkit/build_angular/src/webpack/utils/helpers.ts

@@ -7,6 +7,7 @@
  */
 
 import { basename, normalize } from '@angular-devkit/core';
+import * as path from 'path';
 import { ScriptTarget } from 'typescript';
 import { Options, SourceMapDevToolPlugin } from 'webpack';
 import { ExtraEntryPoint, ExtraEntryPointClass } from '../../browser/schema';
@@ -124,3 +125,30 @@ export function getWatchOptions(poll: number | undefined): Options.WatchOptions
     ignored: poll === undefined ? undefined : withWebpackFourOrFive(/[\\\/]node_modules[\\\/]/, 'node_modules/**'),
   };
 }
+
+export function assetNameTemplateFactory(hashFormat: HashFormat): (resourcePath: string) => string {
+  const visitedFiles = new Map<string, string>();
+
+  return (resourcePath: string) => {
+    if (hashFormat.file) {
+      // File names are hashed therefore we don't need to handle files with the same file name.
+      return `[name]${hashFormat.file}.[ext]`;
+    }
+
+    const filename = path.basename(resourcePath);
+    // Check if the file with the same name has already been processed.
+    const visited = visitedFiles.get(filename);
+    if (!visited) {
+      // Not visited.
+      visitedFiles.set(filename, resourcePath);
+
+      return filename;
+    } else if (visited === resourcePath) {
+      // Same file.
+      return filename;
+    }
+
+    // File has the same name but it's in a different location.
+    return '[path][name].[ext]';
+  };
+}