fix: source map url for devtool (only webpack@5) (#650)

Author: evilebottnawi

src/index.js

@@ -11,7 +11,7 @@ import schema from './plugin-options.json';
 import { MODULE_TYPE, compareModulesByIdentifier } from './utils';
 
 // webpack 5 exposes the sources property to ensure the right version of webpack-sources is used
-const { ConcatSource, SourceMapSource, OriginalSource } =
+const { ConcatSource, SourceMapSource, RawSource } =
   // eslint-disable-next-line global-require
   webpack.sources || require('webpack-sources');
 
@@ -688,7 +688,7 @@ class MiniCssExtractPlugin {
           );
         } else {
           source.add(
-            new OriginalSource(content, m.readableIdentifier(requestShortener))
+            new RawSource(content, m.readableIdentifier(requestShortener))
           );
         }
         source.add('\n');

test/cases/devtool-source-map-no-source-maps-from-css-loader/expected/main.css renamed to test/cases/devtool-source-map-from-loaders/expected/webpack-4/main.css

@@ -0,0 +1,27 @@
+import Self from '../../../src';
+
+module.exports = {
+  entry: './index.js',
+  devtool: 'source-map',
+  module: {
+    rules: [
+      {
+        test: /\.css$/,
+        use: [
+          Self.loader,
+          {
+            loader: 'css-loader',
+            options: {
+              sourceMap: true,
+            },
+          },
+        ],
+      },
+    ],
+  },
+  plugins: [
+    new Self({
+      filename: '[name].css',
+    }),
+  ],
+};