chore: revert changes and update readme

Author: amareshsm

README.md

@@ -239,6 +239,84 @@ module.exports = {
 };
 ```
 
+Note that when using `sass` (`Dart Sass`), **synchronous compilation is twice as fast as asynchronous compilation** by default, due to the overhead of asynchronous callbacks.
+To avoid this overhead, you can use the [fibers](https://www.npmjs.com/package/fibers) package to call asynchronous importers from the synchronous code path.
+
+We automatically inject the [`fibers`](https://github.com/laverdet/node-fibers) package (setup `sassOptions.fiber`) for `Node.js` less v16.0.0 if is possible (i.e. you need install the [`fibers`](https://github.com/laverdet/node-fibers) package).
+
+> ⚠ Fibers is not compatible with `Node.js` v16.0.0 or later. Unfortunately, v8
+> commit [dacc2fee0f](https://github.com/v8/v8/commit/dacc2fee0f815823782a7e432c79c2a7767a4765) is a breaking change and workarounds are non-trivial. ([see introduction to readme](https://github.com/laverdet/node-fibers)).
+
+**package.json**
+
+```json
+{
+  "devDependencies": {
+    "sass-loader": "^7.2.0",
+    "sass": "^1.22.10",
+    "fibers": "^4.0.1"
+  }
+}
+```
+
+You can disable automatically injecting the [`fibers`](https://github.com/laverdet/node-fibers) package by passing a `false` value for the `sassOptions.fiber` option.
+
+**webpack.config.js**
+
+```js
+module.exports = {
+  module: {
+    rules: [
+      {
+        test: /\.s[ac]ss$/i,
+        use: [
+          "style-loader",
+          "css-loader",
+          {
+            loader: "sass-loader",
+            options: {
+              implementation: require("sass"),
+              sassOptions: {
+                fiber: false,
+              },
+            },
+          },
+        ],
+      },
+    ],
+  },
+};
+```
+
+You can also pass the `fiber` value using this code:
+
+**webpack.config.js**
+
+```js
+module.exports = {
+  module: {
+    rules: [
+      {
+        test: /\.s[ac]ss$/i,
+        use: [
+          "style-loader",
+          "css-loader",
+          {
+            loader: "sass-loader",
+            options: {
+              implementation: require("sass"),
+              sassOptions: {
+                fiber: require("fibers"),
+              },
+            },
+          },
+        ],
+      },
+    ],
+  },
+};
+```
+
 ### `sassOptions`
 
 Type:

package-lock.json

@@ -38,6 +38,7 @@
     "dist"
   ],
   "peerDependencies": {
+    "fibers": ">= 3.1.0",
     "node-sass": "^4.0.0 || ^5.0.0 || ^6.0.0 || ^7.0.0",
     "sass": "^1.3.0",
     "sass-embedded": "*",
@@ -52,6 +53,9 @@
     },
     "sass-embedded": {
       "optional": true
+    },
+    "fibers": {
+      "optional": true
     }
   },
   "dependencies": {
@@ -77,6 +81,7 @@
     "eslint": "^8.16.0",
     "eslint-config-prettier": "^8.3.0",
     "eslint-plugin-import": "^2.25.4",
+    "fibers": "^5.0.1",
     "file-loader": "^6.2.0",
     "foundation-sites": "^6.6.3",
     "husky": "^8.0.1",

package.json

@@ -112,6 +112,12 @@ function proxyCustomImporters(importers, loaderContext) {
   );
 }
 
+function isSupportedFibers() {
+  const [nodeVersion] = process.versions.node.split(".");
+
+  return Number(nodeVersion) < 16;
+}
+
 /**
  * Derives the sass options from the loader context and normalizes its values with sane defaults.
  *
@@ -137,6 +143,7 @@ async function getSassOptions(
       : {}
   );
 
+  const isDartSass = implementation.info.includes("dart-sass");
   const isModernAPI = loaderOptions.api === "modern";
 
   options.data = loaderOptions.additionalData
@@ -226,6 +233,32 @@ async function getSassOptions(
   } else {
     options.file = resourcePath;
 
+    if (isDartSass && isSupportedFibers()) {
+      const shouldTryToResolveFibers =
+        !options.fiber && options.fiber !== false;
+
+      if (shouldTryToResolveFibers) {
+        let fibers;
+
+        try {
+          fibers = require.resolve("fibers");
+        } catch (_error) {
+          // Nothing
+        }
+
+        if (fibers) {
+          // eslint-disable-next-line global-require, import/no-dynamic-require
+          options.fiber = require(fibers);
+        }
+      } else if (options.fiber === false) {
+        // Don't pass the `fiber` option for `sass` (`Dart Sass`)
+        delete options.fiber;
+      }
+    } else {
+      // Don't pass the `fiber` option for `node-sass`
+      delete options.fiber;
+    }
+
     // opt.outputStyle
     if (!options.outputStyle && isProductionLikeMode(loaderContext)) {
       options.outputStyle = "compressed";
@@ -775,4 +808,5 @@ export {
   getWebpackImporter,
   getCompileFn,
   normalizeSourceMap,
+  isSupportedFibers,
 };