fix: Remove rspack imports and simplify webpack config

Remove all rspack-related imports and conditional code paths:
- Remove getRspackCore and getRspackReactRefresh imports
- Simplify getWebpackBundler to only return webpack
- Remove rspack conditional branches for:
  - React refresh loaders and plugins
  - JS/CSS minimizers
  - Profiling plugins
  - CSS chunking plugins
  - CSS extract plugins
  - Source map dev tool plugins
  - Remove unused isRspack variable

All code now uses webpack implementations directly without rspack alternatives.

Author: celicoo

packages/next/src/build/webpack-config.ts

@@ -94,8 +94,6 @@ import {
   NEXT_PROJECT_ROOT,
   NEXT_PROJECT_ROOT_DIST_CLIENT,
 } from './next-dir-paths'
-import { getRspackCore, getRspackReactRefresh } from '../shared/lib/get-rspack'
-import { RspackProfilingPlugin } from './webpack/plugins/rspack-profiling-plugin'
 import getWebpackBundler from '../shared/lib/get-webpack-bundler'
 import type { NextBuildContext } from './build-context'
 import type { RootParamsLoaderOpts } from './webpack/loaders/next-root-params-loader'
@@ -177,9 +175,7 @@ const reactRefreshLoaderName =
   'next/dist/compiled/@next/react-refresh-utils/dist/loader'
 
 function getReactRefreshLoader() {
-  return process.env.NEXT_RSPACK
-    ? getRspackReactRefresh().loader
-    : require.resolve(reactRefreshLoaderName)
+  return require.resolve(reactRefreshLoaderName)
 }
 
 export function attachReactRefresh(
@@ -697,11 +693,9 @@ export default async function getBaseWebpackConfig(
     '...',
   ]
 
-  const reactRefreshEntry = isRspack
-    ? getRspackReactRefresh().entry
-    : require.resolve(
-        `next/dist/compiled/@next/react-refresh-utils/dist/runtime`
-      )
+  const reactRefreshEntry = require.resolve(
+    `next/dist/compiled/@next/react-refresh-utils/dist/runtime`
+  )
 
   const clientEntries = isClient
     ? ({
@@ -1230,61 +1224,32 @@ export default async function getBaseWebpackConfig(
           (isNodeServer && config.experimental.serverMinification)),
       minimizer: [
         // Minify JavaScript
-        isRspack
-          ? new (getRspackCore().SwcJsMinimizerRspackPlugin)({
-              // JS minimizer configuration
-              minimizerOptions: {
-                compress: {
-                  inline: 2,
-                  global_defs: {
-                    'process.env.__NEXT_PRIVATE_MINIMIZE_MACRO_FALSE': false,
-                  },
-                },
-                mangle: !noMangling && {
-                  reserved: ['AbortSignal'],
-                  disableCharFreq: !isClient,
-                },
-              },
-            })
-          : (compiler: webpack.Compiler) => {
-              // @ts-ignore No typings yet
-              const { MinifyPlugin } =
-                require('./webpack/plugins/minify-webpack-plugin/src') as typeof import('./webpack/plugins/minify-webpack-plugin/src')
-              new MinifyPlugin({
-                noMangling,
-                disableCharFreq: !isClient,
-              }).apply(compiler)
-            },
+        (compiler: webpack.Compiler) => {
+          // @ts-ignore No typings yet
+          const { MinifyPlugin } =
+            require('./webpack/plugins/minify-webpack-plugin/src') as typeof import('./webpack/plugins/minify-webpack-plugin/src')
+          new MinifyPlugin({
+            noMangling,
+            disableCharFreq: !isClient,
+          }).apply(compiler)
+        },
         // Minify CSS
-        // By default, Rspack uses LightningCSS for CSS minification.
-        // Rspack uses css-minimizer-plugin by default for compatibility.
-        isRspack &&
-        (process.env.__NEXT_TEST_MODE
-          ? config.experimental.useLightningcss
-          : config.experimental?.useLightningcss === undefined ||
-            config.experimental.useLightningcss)
-          ? new (getRspackCore().LightningCssMinimizerRspackPlugin)({
-              // CSS minimizer configuration
-              minimizerOptions: {
-                targets: supportedBrowsers,
+        (compiler: webpack.Compiler) => {
+          const { CssMinimizerPlugin } =
+            require('./webpack/plugins/css-minimizer-plugin') as typeof import('./webpack/plugins/css-minimizer-plugin')
+          new CssMinimizerPlugin({
+            postcssOptions: {
+              map: {
+                // `inline: false` generates the source map in a separate file.
+                // Otherwise, the CSS file is needlessly large.
+                inline: false,
+                // `annotation: false` skips appending the `sourceMappingURL`
+                // to the end of the CSS file. Webpack already handles this.
+                annotation: false,
               },
-            })
-          : (compiler: webpack.Compiler) => {
-              const { CssMinimizerPlugin } =
-                require('./webpack/plugins/css-minimizer-plugin') as typeof import('./webpack/plugins/css-minimizer-plugin')
-              new CssMinimizerPlugin({
-                postcssOptions: {
-                  map: {
-                    // `inline: false` generates the source map in a separate file.
-                    // Otherwise, the CSS file is needlessly large.
-                    inline: false,
-                    // `annotation: false` skips appending the `sourceMappingURL`
-                    // to the end of the CSS file. Webpack already handles this.
-                    annotation: false,
-                  },
-                },
-              }).apply(compiler)
             },
+          }).apply(compiler)
+        },
       ],
     },
     context: dir,
@@ -1983,16 +1948,7 @@ export default async function getBaseWebpackConfig(
           }
         ),
       dev && new MemoryWithGcCachePlugin({ maxGenerations: 5 }),
-      dev &&
-        isClient &&
-        (isRspack
-          ? // eslint-disable-next-line
-            new (getRspackReactRefresh() as any)({
-              injectLoader: false,
-              injectEntry: false,
-              overlay: false,
-            })
-          : new ReactRefreshWebpackPlugin(webpack)),
+      dev && isClient && new ReactRefreshWebpackPlugin(webpack),
       // Makes sure `Buffer` and `process` are polyfilled in client and flight bundles (same behavior as webpack 4)
       (isClient || isEdgeServer) &&
         new bundler.ProvidePlugin({
@@ -2110,9 +2066,7 @@ export default async function getBaseWebpackConfig(
           appDirEnabled: hasAppDir,
           clientRouterFilters,
         }),
-      isRspack
-        ? new RspackProfilingPlugin({ runWebpackSpan })
-        : new ProfilingPlugin({ runWebpackSpan, rootDir: dir }),
+      new ProfilingPlugin({ runWebpackSpan, rootDir: dir }),
       new WellKnownErrorsPlugin(),
       isClient &&
         new CopyFilePlugin({
@@ -2165,14 +2119,7 @@ export default async function getBaseWebpackConfig(
       !dev &&
         isClient &&
         config.experimental.cssChunking &&
-        (isRspack
-          ? new (getRspackCore().experiments.CssChunkingPlugin)({
-              strict: config.experimental.cssChunking === 'strict',
-              nextjs: true,
-            })
-          : new CssChunkingPlugin(
-              config.experimental.cssChunking === 'strict'
-            )),
+        new CssChunkingPlugin(config.experimental.cssChunking === 'strict'),
       telemetryPlugin,
       !dev &&
         isNodeServer &&

packages/next/src/build/webpack/config/blocks/base.ts

@@ -4,7 +4,6 @@ import { COMPILER_NAMES } from '../../../../shared/lib/constants'
 import type { ConfigurationContext } from '../utils'
 import DevToolsIgnorePlugin from '../../plugins/devtools-ignore-list-plugin'
 import EvalSourceMapDevToolPlugin from '../../plugins/eval-source-map-dev-tool-plugin'
-import { getRspackCore } from '../../../../shared/lib/get-rspack'
 
 function shouldIgnorePath(modulePath: string): boolean {
   return (
@@ -67,20 +66,12 @@ export const base = curry(function base(
   } else if (config.devtool === 'eval-source-map') {
     // We're using a fork of `eval-source-map`
     config.devtool = false
-    if (process.env.NEXT_RSPACK) {
-      config.plugins.push(
-        new (getRspackCore().EvalSourceMapDevToolPlugin)({
-          moduleFilenameTemplate: config.output?.devtoolModuleFilenameTemplate,
-        })
-      )
-    } else {
-      config.plugins.push(
-        new EvalSourceMapDevToolPlugin({
-          moduleFilenameTemplate: config.output?.devtoolModuleFilenameTemplate,
-          shouldIgnorePath,
-        })
-      )
-    }
+    config.plugins.push(
+      new EvalSourceMapDevToolPlugin({
+        moduleFilenameTemplate: config.output?.devtoolModuleFilenameTemplate,
+        shouldIgnorePath,
+      })
+    )
   }
 
   // TODO: add codemod for "Should not import the named export" with JSON files

packages/next/src/build/webpack/config/blocks/css/index.ts

@@ -14,7 +14,6 @@ import {
 import { getPostCssPlugins } from './plugins'
 import { nonNullable } from '../../../../../lib/non-nullable'
 import { WEBPACK_LAYERS } from '../../../../../lib/constants'
-import { getRspackCore } from '../../../../../shared/lib/get-rspack'
 
 // RegExps for all Style Sheet variants
 export const regexLikeCss = /\.(css|scss|sass)$/
@@ -148,7 +147,6 @@ export const css = curry(async function css(
   ctx: ConfigurationContext,
   config: webpack.Configuration
 ) {
-  const isRspack = Boolean(process.env.NEXT_RSPACK)
   const {
     prependData: sassPrependData,
     additionalData: sassAdditionalData,
@@ -594,11 +592,9 @@ export const css = curry(async function css(
   // Enable full mini-css-extract-plugin hmr for prod mode pages or app dir
   if (ctx.isClient && (ctx.isProduction || ctx.hasAppDir)) {
     // Extract CSS as CSS file(s) in the client-side production bundle.
-    const MiniCssExtractPlugin = isRspack
-      ? getRspackCore().CssExtractRspackPlugin
-      : (
-          require('../../../plugins/mini-css-extract-plugin') as typeof import('../../../plugins/mini-css-extract-plugin')
-        ).default
+    const MiniCssExtractPlugin = (
+      require('../../../plugins/mini-css-extract-plugin') as typeof import('../../../plugins/mini-css-extract-plugin')
+    ).default
 
     fns.push(
       plugin(

packages/next/src/build/webpack/config/blocks/css/loaders/client.ts

@@ -1,5 +1,4 @@
 import type { webpack } from 'next/dist/compiled/webpack/webpack'
-import { getRspackCore } from '../../../../../../shared/lib/get-rspack'
 
 export function getClientStyleLoader({
   hasAppDir,
@@ -12,7 +11,6 @@ export function getClientStyleLoader({
   isDevelopment: boolean
   assetPrefix: string
 }): webpack.RuleSetUseItem {
-  const isRspack = Boolean(process.env.NEXT_RSPACK)
   const shouldEnableApp = typeof isAppDir === 'boolean' ? isAppDir : hasAppDir
 
   // Keep next-style-loader for development mode in `pages/`
@@ -43,11 +41,9 @@ export function getClientStyleLoader({
     }
   }
 
-  const MiniCssExtractPlugin = isRspack
-    ? getRspackCore().rspack.CssExtractRspackPlugin
-    : (
-        require('../../../../plugins/mini-css-extract-plugin') as typeof import('../../../../plugins/mini-css-extract-plugin')
-      ).default
+  const MiniCssExtractPlugin = (
+    require('../../../../plugins/mini-css-extract-plugin') as typeof import('../../../../plugins/mini-css-extract-plugin')
+  ).default
 
   return {
     loader: MiniCssExtractPlugin.loader,

packages/next/src/shared/lib/get-webpack-bundler.ts

@@ -1,12 +1,10 @@
 import { webpack } from 'next/dist/compiled/webpack/webpack'
-import { getRspackCore } from './get-rspack'
 
 /**
- * Depending on if Rspack is active or not, returns the appropriate set of
- * webpack-compatible api.
+ * Returns the webpack bundler.
  *
  * @returns webpack bundler
  */
 export default function getWebpackBundler(): typeof webpack {
-  return process.env.NEXT_RSPACK ? getRspackCore() : webpack
+  return webpack
 }