feat: improve url() resolving algorithm

.gitignore

@@ -17,3 +17,4 @@ Thumbs.db
 *.sublime-project
 *.sublime-workspace
 /test/fixtures/import/import-absolute.css
+/test/fixtures/url/url-absolute.css

README.md

@@ -125,7 +125,7 @@ Type: `Boolean|Function`
 Default: `true`
 
 Enables/Disables `url`/`image-set` functions handling.
-Control `url()` resolving. Absolute URLs and root-relative URLs are not resolving.
+Control `url()` resolving. Absolute URLs are not resolving.
 
 Examples resolutions:
 
@@ -1174,6 +1174,39 @@ module.exports = {
 };
 ```
 
+### Resolve unresolved URLs using an alias
+
+**index.css**
+
+```css
+.class {
+  background: url(/assets/unresolved/img.png);
+}
+```
+
+**webpack.config.js**
+
+```js
+module.exports = {
+  module: {
+    rules: [
+      {
+        test: /\.css$/i,
+        use: ['style-loader', 'css-loader'],
+      },
+    ],
+  },
+  resolve: {
+    alias: {
+      '/assets/unresolved/img.png': path.resolve(
+        __dirname,
+        'assets/real-path-to-img/img.png'
+      ),
+    },
+  },
+};
+```
+
 ## Contributing
 
 Please take a moment to read our contributing guidelines if you haven't yet done so.

package.json

@@ -40,7 +40,7 @@
     "dist"
   ],
   "peerDependencies": {
-    "webpack": "^4.0.0 || ^5.0.0"
+    "webpack": "^4.27.0 || ^5.0.0"
   },
   "dependencies": {
     "camelcase": "^6.0.0",

src/index.js

@@ -2,7 +2,7 @@
   MIT License http://www.opensource.org/licenses/mit-license.php
   Author Tobias Koppers @sokra
 */
-import { getOptions, isUrlRequest, stringifyRequest } from 'loader-utils';
+import { getOptions, stringifyRequest } from 'loader-utils';
 import postcss from 'postcss';
 import postcssPkg from 'postcss/package.json';
 import validateOptions from 'schema-utils';
@@ -22,6 +22,7 @@ import {
   getModulesPlugins,
   normalizeSourceMap,
   shouldUseModulesPlugins,
+  isUrlRequestable,
 } from './utils';
 
 export default function loader(content, map, meta) {
@@ -95,11 +96,19 @@ export default function loader(content, map, meta) {
   }
 
   if (options.url !== false && exportType === 'full') {
+    const urlResolver = this.getResolve({
+      mainFields: ['asset'],
+      conditionNames: ['asset'],
+    });
+
     plugins.push(
       urlParser({
+        context: this.context,
+        rootContext: this.rootContext,
         filter: getFilter(options.url, this.resourcePath, (value) =>
-          isUrlRequest(value)
+          isUrlRequestable(value)
         ),
+        resolver: urlResolver,
         urlHandler: (url) => stringifyRequest(this, url),
       })
     );