refactor: sourcemap paths

BREAKING CHANGE: source map contains absolute `sources`

package.json

@@ -44,6 +44,7 @@
   "dependencies": {
     "cosmiconfig": "^7.0.0",
     "loader-utils": "^2.0.0",
+    "normalize-path": "^3.0.0",
     "postcss": "^7.0.0",
     "schema-utils": "^2.7.0"
   },
@@ -67,6 +68,7 @@
     "jest": "^26.2.2",
     "jest-junit": "^11.1.0",
     "jsdoc-to-markdown": "^6.0.1",
+    "less-loader": "^6.2.0",
     "lint-staged": "^10.2.11",
     "memfs": "^3.2.0",
     "midas": "^2.0.3",

src/index.js

@@ -8,7 +8,14 @@ import postcss from 'postcss';
 import Warning from './Warning';
 import SyntaxError from './Error';
 import schema from './options.json';
-import { exec, loadConfig, getArrayPlugins } from './utils';
+import {
+  exec,
+  loadConfig,
+  getArrayPlugins,
+  getSourceMapAbsolutePath,
+  getSourceMapRelativePath,
+  normalizeSourceMap,
+} from './utils';
 
 /**
  * **PostCSS Loader**
@@ -103,8 +110,18 @@ export default async function loader(content, sourceMap, meta = {}) {
       ? options.sourceMap
       : this.sourceMap;
 
+  const sourceMapNormalized =
+    sourceMap && useSourceMap ? normalizeSourceMap(sourceMap) : null;
+
+  if (sourceMapNormalized) {
+    sourceMapNormalized.sources = sourceMapNormalized.sources.map((src) =>
+      getSourceMapRelativePath(src, path.dirname(file))
+    );
+  }
+
   const postcssOptions = {
     from: file,
+    to: file,
     map: useSourceMap
       ? options.sourceMap === 'inline'
         ? { inline: true, annotation: false }
@@ -115,9 +132,8 @@ export default async function loader(content, sourceMap, meta = {}) {
     stringifier,
   };
 
-  if (postcssOptions.map && sourceMap) {
-    postcssOptions.map.prev =
-      typeof sourceMap === 'string' ? JSON.parse(sourceMap) : sourceMap;
+  if (postcssOptions.map && sourceMapNormalized) {
+    postcssOptions.map.prev = sourceMapNormalized;
   }
 
   // Loader Exec (Deprecated)
@@ -210,8 +226,13 @@ export default async function loader(content, sourceMap, meta = {}) {
   map = map ? map.toJSON() : null;
 
   if (map) {
-    map.file = path.resolve(map.file);
-    map.sources = map.sources.map((src) => path.resolve(src));
+    if (typeof map.file !== 'undefined') {
+      delete map.file;
+    }
+
+    map.sources = map.sources.map((src) =>
+      getSourceMapAbsolutePath(src, postcssOptions.to)
+    );
   }
 
   const ast = {

src/utils.js

@@ -2,6 +2,8 @@ import path from 'path';
 
 import Module from 'module';
 
+import normalizePath from 'normalize-path';
+
 import postcssPkg from 'postcss/package.json';
 import { cosmiconfig } from 'cosmiconfig';
 
@@ -242,4 +244,75 @@ function getArrayPlugins(plugins, file, disabledPlugins, loaderContext) {
   return pluginsProcessing(plugins, file, disabledPlugins);
 }
 
-export { exec, loadConfig, getArrayPlugins };
+// TODO Remove, when postcss 8 will be released
+function normalizeSourceMap(map) {
+  let newMap = map;
+
+  // Some loader emit source map as string
+  // Strip any JSON XSSI avoidance prefix from the string (as documented in the source maps specification), and then parse the string as JSON.
+  if (typeof newMap === 'string') {
+    newMap = JSON.parse(newMap);
+  }
+
+  // Source maps should use forward slash because it is URLs (https://github.com/mozilla/source-map/issues/91)
+  // We should normalize path because previous loaders like `sass-loader` using backslash when generate source map
+
+  if (newMap.file) {
+    delete newMap.file;
+  }
+
+  const { sourceRoot } = newMap;
+
+  if (newMap.sourceRoot) {
+    delete newMap.sourceRoot;
+  }
+
+  if (newMap.sources) {
+    newMap.sources = newMap.sources.map((source) => {
+      return !sourceRoot
+        ? normalizePath(source)
+        : normalizePath(path.resolve(sourceRoot, source));
+    });
+  }
+
+  return newMap;
+}
+
+function getSourceMapRelativePath(file, from) {
+  if (file.indexOf('<') === 0) return file;
+  if (/^\w+:\/\//.test(file)) return file;
+
+  const result = path.relative(from, file);
+
+  if (path.sep === '\\') {
+    return result.replace(/\\/g, '/');
+  }
+
+  return result;
+}
+
+function getSourceMapAbsolutePath(file, to) {
+  if (file.indexOf('<') === 0) return file;
+  if (/^\w+:\/\//.test(file)) return file;
+
+  if (typeof to === 'undefined') return file;
+
+  const dirname = path.dirname(to);
+
+  const result = path.resolve(dirname, file);
+
+  if (path.sep === '\\') {
+    return result.replace(/\\/g, '/');
+  }
+
+  return result;
+}
+
+export {
+  exec,
+  loadConfig,
+  getArrayPlugins,
+  getSourceMapAbsolutePath,
+  getSourceMapRelativePath,
+  normalizeSourceMap,
+};

test/fixtures/less/index.js

@@ -0,0 +1,3 @@
+import style from './style.less'
+
+export default style

test/fixtures/less/style.less

@@ -0,0 +1 @@
+a { color: coral }

test/helpers/getCodeFromBundle.js

@@ -1,6 +1,6 @@
 import normalizeMap from './normalizeMap';
 
-export default (id, stats) => {
+export default (id, stats, processMap = true) => {
   const { modules } = stats.compilation;
   const module = modules.find((m) => m.id.endsWith(id));
   const { _source } = module;
@@ -21,5 +21,5 @@ export default (id, stats) => {
 
   const { css, map } = result;
 
-  return { css, map: normalizeMap(map) };
+  return { css, map: processMap ? normalizeMap(map) : map };
 };

test/options/__snapshots__/sourceMap.test.js.snap

@@ -1,5 +1,29 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`Options Sourcemap should generated absolute paths in sourcemap: css 1`] = `
+"a { color: black }
+"
+`;
+
+exports[`Options Sourcemap should generated absolute paths in sourcemap: errors 1`] = `Array []`;
+
+exports[`Options Sourcemap should generated absolute paths in sourcemap: map 1`] = `
+Object {
+  "mappings": "AAAA,IAAI,aAAa",
+  "names": Array [],
+  "sources": Array [
+    "xxx",
+  ],
+  "sourcesContent": Array [
+    "a { color: black }
+",
+  ],
+  "version": 3,
+}
+`;
+
+exports[`Options Sourcemap should generated absolute paths in sourcemap: warnings 1`] = `Array []`;
+
 exports[`Options Sourcemap should work Sourcemap - {Boolean}: css 1`] = `
 "a { color: black }
 "
@@ -9,7 +33,6 @@ exports[`Options Sourcemap should work Sourcemap - {Boolean}: errors 1`] = `Arra
 
 exports[`Options Sourcemap should work Sourcemap - {Boolean}: map 1`] = `
 Object {
-  "file": "x",
   "mappings": "AAAA,IAAI,aAAa",
   "names": Array [],
   "sources": Array [
@@ -28,7 +51,7 @@ exports[`Options Sourcemap should work Sourcemap - {Boolean}: warnings 1`] = `Ar
 exports[`Options Sourcemap should work Sourcemap - {String}: css 1`] = `
 "a { color: black }
 
-/*# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbInRlc3QvZml4dHVyZXMvY3NzL3N0eWxlLmNzcyJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiQUFBQSxJQUFJLGFBQWEiLCJmaWxlIjoidGVzdC9maXh0dXJlcy9jc3Mvc3R5bGUuY3NzIiwic291cmNlc0NvbnRlbnQiOlsiYSB7IGNvbG9yOiBibGFjayB9XG4iXX0= */"
+/*# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbInN0eWxlLmNzcyJdLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiQUFBQSxJQUFJLGFBQWEiLCJmaWxlIjoic3R5bGUuY3NzIiwic291cmNlc0NvbnRlbnQiOlsiYSB7IGNvbG9yOiBibGFjayB9XG4iXX0= */"
 `;
 
 exports[`Options Sourcemap should work Sourcemap - {String}: errors 1`] = `Array []`;
@@ -44,32 +67,53 @@ exports[`Options Sourcemap should work disable Sourcemap - {Boolean}: errors 1`]
 
 exports[`Options Sourcemap should work disable Sourcemap - {Boolean}: warnings 1`] = `Array []`;
 
-exports[`Options Sourcemap should work with prev sourceMap: css 1`] = `
+exports[`Options Sourcemap should work with prev sourceMap (less-loader): css 1`] = `
 "a {
   color: coral;
-}"
+}
+"
 `;
 
-exports[`Options Sourcemap should work with prev sourceMap: errors 1`] = `Array []`;
+exports[`Options Sourcemap should work with prev sourceMap (less-loader): errors 1`] = `Array []`;
 
-exports[`Options Sourcemap should work with prev sourceMap: map 1`] = `
+exports[`Options Sourcemap should work with prev sourceMap (less-loader): map 1`] = `
 Object {
-  "file": "x",
-  "mappings": "AAAA;EAAI,YAAA;ACEJ",
+  "mappings": "AAAA;EAAI,YAAA;AAEJ",
   "names": Array [],
   "sources": Array [
     "xxx",
-    "xxx",
   ],
   "sourcesContent": Array [
     "a { color: coral }
 ",
-    "a {
+  ],
+  "version": 3,
+}
+`;
+
+exports[`Options Sourcemap should work with prev sourceMap (less-loader): warnings 1`] = `Array []`;
+
+exports[`Options Sourcemap should work with prev sourceMap (sass-loader): css 1`] = `
+"a {
   color: coral;
-}",
+}"
+`;
+
+exports[`Options Sourcemap should work with prev sourceMap (sass-loader): errors 1`] = `Array []`;
+
+exports[`Options Sourcemap should work with prev sourceMap (sass-loader): map 1`] = `
+Object {
+  "mappings": "AAAA;EAAI,YAAA;AAEJ",
+  "names": Array [],
+  "sources": Array [
+    "xxx",
+  ],
+  "sourcesContent": Array [
+    "a { color: coral }
+",
   ],
   "version": 3,
 }
 `;
 
-exports[`Options Sourcemap should work with prev sourceMap: warnings 1`] = `Array []`;
+exports[`Options Sourcemap should work with prev sourceMap (sass-loader): warnings 1`] = `Array []`;