From ea02b6e94710d43ab9c2738765c17d234dce353e Mon Sep 17 00:00:00 2001
From: Charles Lyding <19598772+clydin@users.noreply.github.com>
Date: Thu, 29 Oct 2020 12:50:46 -0400
Subject: [PATCH] fix(@angular-devkit/build-angular): re-enable webpack 5
 license extraction support

With updates to the `license-webpack-plugin` and adjustments to the web worker plugin configuration, license extraction can now be used with webpack 5.  This change also removes the need to filter out the duplicate asset warning on Webpack 4 that was previously being generated.
---
 .../build_angular/src/browser/index.ts        |  9 --------
 .../src/webpack/configs/browser.ts            |  1 +
 .../src/webpack/configs/worker.ts             | 21 ++++++++++++++++---
 .../build_angular/src/webpack/utils/stats.ts  |  2 --
 4 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/packages/angular_devkit/build_angular/src/browser/index.ts b/packages/angular_devkit/build_angular/src/browser/index.ts
index b02b894d9ff3..d0acb430b87b 100644
--- a/packages/angular_devkit/build_angular/src/browser/index.ts
+++ b/packages/angular_devkit/build_angular/src/browser/index.ts
@@ -152,15 +152,6 @@ async function initialize(
   // Assets are processed directly by the builder except when watching
   const adjustedOptions = options.watch ? options : { ...options, assets: [] };
 
-  // TODO_WEBPACK_5: Investigate build/serve issues with the `license-webpack-plugin` package
-  if (adjustedOptions.extractLicenses && isWebpackFiveOrHigher()) {
-    adjustedOptions.extractLicenses = false;
-    context.logger.warn(
-      'Warning: License extraction is currently disabled when using Webpack 5. ' +
-        'This is temporary and will be corrected in a future update.',
-    );
-  }
-
   const {
     config,
     projectRoot,
diff --git a/packages/angular_devkit/build_angular/src/webpack/configs/browser.ts b/packages/angular_devkit/build_angular/src/webpack/configs/browser.ts
index d0a48c74fb6c..26bb7d911484 100644
--- a/packages/angular_devkit/build_angular/src/webpack/configs/browser.ts
+++ b/packages/angular_devkit/build_angular/src/webpack/configs/browser.ts
@@ -47,6 +47,7 @@ export function getBrowserConfig(wco: WebpackConfigOptions): webpack.Configurati
       },
       perChunkOutput: false,
       outputFilename: '3rdpartylicenses.txt',
+      skipChildCompilers: true,
     }));
   }
 
diff --git a/packages/angular_devkit/build_angular/src/webpack/configs/worker.ts b/packages/angular_devkit/build_angular/src/webpack/configs/worker.ts
index 318f1ac09df0..9ef16f3bfe7d 100644
--- a/packages/angular_devkit/build_angular/src/webpack/configs/worker.ts
+++ b/packages/angular_devkit/build_angular/src/webpack/configs/worker.ts
@@ -22,12 +22,27 @@ export function getWorkerConfig(wco: WebpackConfigOptions): Configuration {
   }
 
   const workerTsConfigPath = resolve(wco.root, buildOptions.webWorkerTsConfig);
-  const WorkerPlugin = require('worker-plugin');
+  const WebWorkerPlugin = require('worker-plugin');
+
+  const workerPlugins = [getTypescriptWorkerPlugin(wco, workerTsConfigPath)];
+  if (buildOptions.extractLicenses) {
+    // Webpack child compilations will not inherit the license plugin
+    const LicenseWebpackPlugin = require('license-webpack-plugin').LicenseWebpackPlugin;
+    workerPlugins.push(new LicenseWebpackPlugin({
+      stats: {
+        warnings: false,
+        errors: false,
+      },
+      perChunkOutput: false,
+      // The name needs to be unique to this child compilation to avoid duplicate asset errors
+      outputFilename: '3rdpartylicenses-worker-[hash].txt',
+    }));
+  }
 
   return {
-    plugins: [new WorkerPlugin({
+    plugins: [new WebWorkerPlugin({
       globalObject: false,
-      plugins: [getTypescriptWorkerPlugin(wco, workerTsConfigPath)],
+      plugins: workerPlugins,
     })],
   };
 }
diff --git a/packages/angular_devkit/build_angular/src/webpack/utils/stats.ts b/packages/angular_devkit/build_angular/src/webpack/utils/stats.ts
index 0a4b1faa0704..0ddbaf47fb2a 100644
--- a/packages/angular_devkit/build_angular/src/webpack/utils/stats.ts
+++ b/packages/angular_devkit/build_angular/src/webpack/utils/stats.ts
@@ -140,8 +140,6 @@ export function statsToString(json: any, statsConfig: any) {
 }
 
 const ERRONEOUS_WARNINGS_FILTER = (warning: string) => ![
-  // TODO(#16193): Don't emit this warning in the first place rather than just suppressing it.
-  /multiple assets emit different content.*3rdpartylicenses\.txt/i,
   // Webpack 5+ has no facility to disable this warning.
   // System.import is used in @angular/core for deprecated string-form lazy routes
   /System.import\(\) is deprecated and will be removed soon/i,