fix: memory leak

README.md

@@ -34,7 +34,8 @@ module.exports = {
     rules: [
       {
         test: /\.less$/i,
-        loader: [ // compiles Less to CSS
+        loader: [
+          // compiles Less to CSS
           "style-loader",
           "css-loader",
           "less-loader",
@@ -529,13 +530,13 @@ module.exports = {
 };
 ```
 
-> ℹ️ Access to the [loader context](https://webpack.js.org/api/loaders/#the-loader-context) inside the custom plugin can be done using the `less.webpackLoaderContext` property.
+> ℹ️ Access to the [loader context](https://webpack.js.org/api/loaders/#the-loader-context) inside the custom plugin can be done using the `pluginManager.webpackLoaderContext` property.
 
 ```js
 module.exports = {
   install: function (less, pluginManager, functions) {
     functions.add("pi", function () {
-      // Loader context is available in `less.webpackLoaderContext`
+      // Loader context is available in `pluginManager.webpackLoaderContext`
 
       return Math.PI;
     });

src/index.js

@@ -44,6 +44,10 @@ async function lessLoader(source) {
     return;
   }
 
+  if ("webpackLoaderContext" in less) {
+    delete less.webpackLoaderContext;
+  }
+
   const { css, imports } = result;
 
   imports.forEach((item) => {

src/utils.js

@@ -1,4 +1,5 @@
 import path from "path";
+import util from "util";
 
 import less from "less";
 import { klona } from "klona/full";
@@ -181,10 +182,26 @@ function getLessOptions(loaderContext, loaderOptions) {
     lessOptions.plugins.unshift(createWebpackLessPlugin(loaderContext));
   }
 
+  const webpackContextDeprecated = util.deprecate(
+    (context) => context,
+    "less.webpackLoaderContext is deprecated and will be removed in next major release. Instead use pluginManager.webpackLoaderContext (https://webpack.js.org/loaders/less-loader/#plugins)"
+  );
+
   lessOptions.plugins.unshift({
-    install(lessProcessor) {
+    install(lessProcessor, pluginManager) {
       // eslint-disable-next-line no-param-reassign
-      lessProcessor.webpackLoaderContext = loaderContext;
+      pluginManager.webpackLoaderContext = loaderContext;
+
+      // Todo remove in next major release
+      if (typeof lessProcessor.webpackLoaderContext === "undefined") {
+        Object.defineProperty(lessProcessor, "webpackLoaderContext", {
+          configurable: true,
+
+          get() {
+            return webpackContextDeprecated(loaderContext);
+          },
+        });
+      }
     },
   });
 

test/__snapshots__/loader.test.js.snap

@@ -92,26 +92,26 @@ exports[`loader should delegate resolving (LESS) imports with URLs to "less" pac
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 300;
-  src: url(https://fonts.gstatic.com/s/roboto/v20/KFOlCnqEu92Fr1MmSU5fBBc9.ttf) format('truetype');
+  src: url(https://fonts.gstatic.com/s/roboto/v27/KFOlCnqEu92Fr1MmSU5fBBc9.ttf) format('truetype');
 }
 
 @font-face {
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 400;
-  src: url(https://fonts.gstatic.com/s/roboto/v20/KFOmCnqEu92Fr1Mu4mxP.ttf) format('truetype');
+  src: url(https://fonts.gstatic.com/s/roboto/v27/KFOmCnqEu92Fr1Mu4mxP.ttf) format('truetype');
 }
 @font-face {
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 500;
-  src: url(https://fonts.gstatic.com/s/roboto/v20/KFOlCnqEu92Fr1MmEU9fBBc9.ttf) format('truetype');
+  src: url(https://fonts.gstatic.com/s/roboto/v27/KFOlCnqEu92Fr1MmEU9fBBc9.ttf) format('truetype');
 }
 @font-face {
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 700;
-  src: url(https://fonts.gstatic.com/s/roboto/v20/KFOlCnqEu92Fr1MmWUlfBBc9.ttf) format('truetype');
+  src: url(https://fonts.gstatic.com/s/roboto/v27/KFOlCnqEu92Fr1MmWUlfBBc9.ttf) format('truetype');
 }
 "
 `;
@@ -157,25 +157,25 @@ exports[`loader should not add to dependencies imports with URLs: css 1`] = `
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 300;
-  src: url(http://fonts.gstatic.com/s/roboto/v20/KFOlCnqEu92Fr1MmSU5fBBc9.ttf) format('truetype');
+  src: url(http://fonts.gstatic.com/s/roboto/v27/KFOlCnqEu92Fr1MmSU5fBBc9.ttf) format('truetype');
 }
 @font-face {
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 300;
-  src: url(https://fonts.gstatic.com/s/roboto/v20/KFOlCnqEu92Fr1MmSU5fBBc9.ttf) format('truetype');
+  src: url(https://fonts.gstatic.com/s/roboto/v27/KFOlCnqEu92Fr1MmSU5fBBc9.ttf) format('truetype');
 }
 @font-face {
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 400;
-  src: url(https://fonts.gstatic.com/s/roboto/v20/KFOmCnqEu92Fr1Mu4mxP.ttf) format('truetype');
+  src: url(https://fonts.gstatic.com/s/roboto/v27/KFOmCnqEu92Fr1Mu4mxP.ttf) format('truetype');
 }
 @font-face {
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 500;
-  src: url(https://fonts.gstatic.com/s/roboto/v20/KFOlCnqEu92Fr1MmEU9fBBc9.ttf) format('truetype');
+  src: url(https://fonts.gstatic.com/s/roboto/v27/KFOlCnqEu92Fr1MmEU9fBBc9.ttf) format('truetype');
 }
 "
 `;
@@ -579,6 +579,17 @@ exports[`loader should work lessOptions.relativeUrls is true: errors 1`] = `Arra
 
 exports[`loader should work lessOptions.relativeUrls is true: warnings 1`] = `Array []`;
 
+exports[`loader should work loaderContext in less plugins 2: css 1`] = `
+".webpackLoaderContext {
+  isDefined: true;
+}
+"
+`;
+
+exports[`loader should work loaderContext in less plugins 2: errors 1`] = `Array []`;
+
+exports[`loader should work loaderContext in less plugins 2: warnings 1`] = `Array []`;
+
 exports[`loader should work loaderContext in less plugins: css 1`] = `
 ".webpackLoaderContext {
   isDefined: true;
@@ -598,7 +609,7 @@ exports[`loader should work third-party plugins as fileLoader: css 1`] = `
   font-family: 'Roboto';
   font-style: normal;
   font-weight: 500;
-  src: url(https://fonts.gstatic.com/s/roboto/v20/KFOlCnqEu92Fr1MmEU9fBBc9.ttf) format('truetype');
+  src: url(https://fonts.gstatic.com/s/roboto/v27/KFOlCnqEu92Fr1MmEU9fBBc9.ttf) format('truetype');
 }
 .modules-dir-scope-module {
   color: hotpink;

test/fixtures/basic-plugins-2.less

@@ -0,0 +1,5 @@
+@plugin "plugin-2";
+
+.webpackLoaderContext {
+  isDefined: run();
+}

test/fixtures/plugin-2.js

@@ -0,0 +1,11 @@
+registerPlugin({
+  install: function(less, pluginManager, functions) {
+    functions.add('run', function() {
+      if (typeof pluginManager.webpackLoaderContext !== 'undefined') {
+        return 'true';
+      }
+
+      return 'false';
+    });
+  }
+})

test/loader.test.js

@@ -802,7 +802,7 @@ describe("loader", () => {
       constructor(less) {
         super();
 
-        if (typeof less.webpackLoaderContext !== "undefined") {
+        if (typeof less.webpackLoaderContext.version !== "undefined") {
           contextInClass = true;
         }
       }
@@ -817,7 +817,7 @@ describe("loader", () => {
 
     const customObjectPlugin = {
       install(less) {
-        if (typeof less.webpackLoaderContext !== "undefined") {
+        if (typeof less.webpackLoaderContext.version !== "undefined") {
           contextInObject = true;
         }
       },
@@ -839,6 +839,52 @@ describe("loader", () => {
     expect(getErrors(stats)).toMatchSnapshot("errors");
   });
 
+  it("should work loaderContext in less plugins 2", async () => {
+    let contextInClass;
+    let contextInObject;
+
+    // eslint-disable-next-line global-require
+    class Plugin extends require("less").FileManager {
+      constructor(less, pluginManager) {
+        super();
+
+        if (typeof pluginManager.webpackLoaderContext !== "undefined") {
+          contextInClass = true;
+        }
+      }
+    }
+
+    class CustomClassPlugin {
+      // eslint-disable-next-line class-methods-use-this
+      install(less, pluginManager) {
+        pluginManager.addFileManager(new Plugin(less, pluginManager));
+      }
+    }
+
+    const customObjectPlugin = {
+      install(less, packageManager) {
+        if (typeof packageManager.webpackLoaderContext !== "undefined") {
+          contextInObject = true;
+        }
+      },
+    };
+
+    const testId = "./basic-plugins-2.less";
+    const compiler = getCompiler(testId, {
+      lessOptions: {
+        plugins: [new CustomClassPlugin(), customObjectPlugin],
+      },
+    });
+    const stats = await compile(compiler);
+    const codeFromBundle = getCodeFromBundle(stats, compiler);
+
+    expect(contextInClass).toBe(true);
+    expect(contextInObject).toBe(true);
+    expect(codeFromBundle.css).toMatchSnapshot("css");
+    expect(getWarnings(stats)).toMatchSnapshot("warnings");
+    expect(getErrors(stats)).toMatchSnapshot("errors");
+  });
+
   // TODO bug on windows
   it.skip("should work with circular imports", async () => {
     const testId = "./circular.less";