fix: compatibility with ECMA modules less version

babel.config.js

@@ -12,6 +12,7 @@ module.exports = (api) => {
           targets: {
             node: "18.12.0",
           },
+          exclude: ["transform-dynamic-import"],
         },
       ],
     ],

package.json

@@ -38,7 +38,7 @@
     "fix:js": "npm run lint:js -- --fix",
     "fix:prettier": "npm run lint:prettier -- --write",
     "fix": "npm-run-all -l fix:js fix:prettier",
-    "test:only": "cross-env NODE_ENV=test jest",
+    "test:only": "node --experimental-vm-modules node_modules/jest-cli/bin/jest.js",
     "test:watch": "npm run test:only -- --watch",
     "test:coverage": "npm run test:only -- --collectCoverageFrom=\"src/**/*.js\" --coverage",
     "pretest": "npm run lint",
@@ -71,7 +71,7 @@
     "globals": "^16.3.0",
     "husky": "^9.1.3",
     "jest": "^30.0.0",
-    "less": "^4.2.0",
+    "less": "^4.6.2",
     "less-plugin-glob": "^3.0.0",
     "lint-staged": "^15.2.7",
     "memfs": "^4.9.3",

src/index.js

@@ -15,7 +15,7 @@ async function lessLoader(source) {
   let implementation;
 
   try {
-    implementation = getLessImplementation(this, options.implementation);
+    implementation = await getLessImplementation(this, options.implementation);
   } catch (error) {
     callback(error);
 
@@ -38,7 +38,9 @@ async function lessLoader(source) {
 
   if (useSourceMap) {
     lessOptions.sourceMap = {
+      sourceMapBasepath: "",
       outputSourceFiles: true,
+      disableSourcemapAnnotation: true,
     };
   }
 
@@ -123,7 +125,7 @@ async function lessLoader(source) {
     typeof result.map === "string" ? JSON.parse(result.map) : result.map;
 
   if (map && useSourceMap) {
-    map = normalizeSourceMap(map, this.rootContext);
+    map = normalizeSourceMap(map);
   }
 
   callback(null, css, map);

src/utils.js

@@ -223,20 +223,19 @@ function normalizeSourceMap(map) {
 
   newMap.sourceRoot = "";
 
-  // `less` returns POSIX paths, that's why we need to transform them back to native paths.
-
+  // `less` (old versions) returns POSIX paths, that's why we need to transform them back to native paths.
   newMap.sources = newMap.sources.map((source) => path.normalize(source));
 
   return newMap;
 }
 
-function getLessImplementation(loaderContext, implementation) {
+async function getLessImplementation(loaderContext, implementation) {
   let resolvedImplementation = implementation;
 
   if (!implementation || typeof implementation === "string") {
     const lessImplPkg = implementation || "less";
 
-    resolvedImplementation = require(lessImplPkg);
+    resolvedImplementation = (await import(lessImplPkg)).default;
   }
 
   return resolvedImplementation;