Update bundler for pre-bundling runtime (#75294)

This improves the build script quite a bit and makes dev editing much
faster. Also fixed excludes causing webpack/babel compiled packages to
be bundled into the runtime un-necessarily reducing from `10MB` ->
`1.2MB`.

Before: `Finished next_bundle in 9.67s`

After: `Finished next_bundle in 1.27s`

Validated here
https://github.com/vercel/vercel/actions/runs/12957911052/job/36147343396?pr=12914

Author: ijjk

.eslintrc.json

@@ -162,7 +162,7 @@
       "files": ["packages/**"],
       "excludedFiles": [
         "packages/next/taskfile*.js",
-        "packages/next/next-runtime.webpack-config.js"
+        "packages/next/next_runtime.config.js"
       ],
       "rules": {
         "no-shadow": ["error", { "builtinGlobals": false }],

packages/next/next-runtime.webpack-config.js renamed to packages/next/next_runtime.config.js

@@ -1,11 +1,9 @@
-const webpack = require('webpack')
+const webpack = require('@rspack/core')
 const path = require('path')
-const TerserPlugin = require('terser-webpack-plugin')
 const { BundleAnalyzerPlugin } = require('webpack-bundle-analyzer')
-const EvalSourceMapDevToolPlugin = require('./webpack-plugins/eval-source-map-dev-tool-plugin')
 const DevToolsIgnoreListPlugin = require('./webpack-plugins/devtools-ignore-list-plugin')
 
-function shouldIgnorePath(modulePath) {
+function shouldIgnorePath() {
   // For consumers, everything will be considered 3rd party dependency if they use
   // the bundles we produce here.
   // In other words, this is all library code and should therefore be ignored.
@@ -130,6 +128,11 @@ const bundleTypes = {
 module.exports = ({ dev, turbo, bundleType, experimental }) => {
   const externalHandler = ({ context, request, getResolve }, callback) => {
     ;(async () => {
+      if (request.match(/next[/\\]dist[/\\]compiled[/\\](babel|webpack)/)) {
+        callback(null, 'commonjs ' + request)
+        return
+      }
+
       if (request.endsWith('.external')) {
         const resolve = getResolve()
         const resolved = await resolve(context, request)
@@ -156,44 +159,23 @@ module.exports = ({ dev, turbo, bundleType, experimental }) => {
   return {
     entry: bundleTypes[bundleType],
     target: 'node',
-    mode: 'production',
+    mode: dev ? 'development' : 'production',
     output: {
       path: path.join(__dirname, 'dist/compiled/next-server'),
       filename: `[name]${turbo ? '-turbo' : ''}${
         experimental ? '-experimental' : ''
       }.runtime.${dev ? 'dev' : 'prod'}.js`,
       libraryTarget: 'commonjs2',
     },
-    devtool: process.env.NEXT_SERVER_EVAL_SOURCE_MAPS
-      ? // We'll use a fork in plugins
-        false
-      : 'source-map',
+    devtool: 'source-map',
     optimization: {
       moduleIds: 'named',
       minimize: true,
       concatenateModules: true,
-      minimizer: [
-        new TerserPlugin({
-          minify: TerserPlugin.swcMinify,
-          terserOptions: {
-            compress: {
-              dead_code: true,
-              // Zero means no limit.
-              passes: 0,
-            },
-            format: {
-              preamble: '',
-            },
-            mangle:
-              dev && !process.env.NEXT_SERVER_EVAL_SOURCE_MAPS ? false : true,
-          },
-        }),
-      ],
+      minimizer: [new webpack.SwcJsMinimizerRspackPlugin()],
     },
     plugins: [
-      process.env.NEXT_SERVER_EVAL_SOURCE_MAPS
-        ? new EvalSourceMapDevToolPlugin({ shouldIgnorePath })
-        : new DevToolsIgnoreListPlugin({ shouldIgnorePath }),
+      new DevToolsIgnoreListPlugin({ shouldIgnorePath }),
       new webpack.DefinePlugin({
         'typeof window': JSON.stringify('undefined'),
         'process.env.NEXT_MINIMAL': JSON.stringify('true'),

packages/next/package.json

@@ -80,7 +80,7 @@
     "next": "./dist/bin/next"
   },
   "scripts": {
-    "dev": "cross-env NEXT_SERVER_EVAL_SOURCE_MAPS=1 taskr",
+    "dev": "taskr",
     "release": "taskr release",
     "build": "pnpm release",
     "prepublishOnly": "cd ../../ && turbo run build",
@@ -92,7 +92,7 @@
   },
   "taskr": {
     "requires": [
-      "./taskfile-webpack.js",
+      "./taskfile-rspack.js",
       "./taskfile-ncc.js",
       "./taskfile-swc.js",
       "./taskfile-watch.js"
@@ -171,6 +171,7 @@
     "@next/swc": "15.2.0-canary.25",
     "@opentelemetry/api": "1.6.0",
     "@playwright/test": "1.41.2",
+    "@rspack/core": "1.2.2",
     "@storybook/addon-essentials": "^8.4.7",
     "@storybook/addon-interactions": "^8.4.7",
     "@storybook/addon-onboarding": "^8.4.7",

packages/next/src/compiled/sass-loader/cjs.js

@@ -1330,9 +1330,12 @@ export default class NextNodeServer extends BaseServer<
   }
 
   protected getMiddlewareManifest(): MiddlewareManifest | null {
-    if (this.minimalMode) return null
-    const manifest: MiddlewareManifest = require(this.middlewareManifestPath)
-    return manifest
+    if (this.minimalMode) {
+      return null
+    } else {
+      const manifest: MiddlewareManifest = require(this.middlewareManifestPath)
+      return manifest
+    }
   }
 
   /** Returns the middleware routing item if there is one. */

packages/next/src/server/next-server.ts

@@ -1,11 +1,11 @@
-const webpack = require('webpack')
+const rspack = require('@rspack/core')
 
 module.exports = function (task) {
   // eslint-disable-next-line require-yield
-  task.plugin('webpack', {}, function* (_, options) {
+  task.plugin('rspack', {}, function* (_, options) {
     options = options || {}
 
-    const compiler = webpack(options.config)
+    const compiler = rspack(options.config)
 
     if (options.watch) {
       return compiler.watch({}, (err, stats) => {
@@ -21,15 +21,15 @@ module.exports = function (task) {
       compiler.run((err, stats) => {
         if (err || stats.hasErrors()) {
           return this.emit('plugin_error', {
-            plugin: 'taskfile-webpack',
+            plugin: 'taskfile-rspack',
             error: err?.message ?? stats.toString(),
           })
         }
 
         if (stats.hasWarnings()) {
           this.emit('plugin_warning', {
-            plugin: 'taskfile-webpack',
-            warning: `webpack compiled ${options.name} with warnings:\n${stats.toString('errors-warnings')}`,
+            plugin: 'taskfile-rspack',
+            warning: `rspack compiled ${options.name} with warnings:\n${stats.toString('errors-warnings')}`,
           })
         }
 

packages/next/taskfile-webpack.js renamed to packages/next/taskfile-rspack.js

@@ -2846,9 +2846,9 @@ export async function release(task) {
 }
 
 export async function next_bundle_app_turbo(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       turbo: true,
       bundleType: 'app',
     }),
@@ -2857,9 +2857,9 @@ export async function next_bundle_app_turbo(task, opts) {
 }
 
 export async function next_bundle_app_prod(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       dev: false,
       bundleType: 'app',
     }),
@@ -2868,9 +2868,9 @@ export async function next_bundle_app_prod(task, opts) {
 }
 
 export async function next_bundle_app_dev(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       dev: true,
       bundleType: 'app',
     }),
@@ -2879,9 +2879,9 @@ export async function next_bundle_app_dev(task, opts) {
 }
 
 export async function next_bundle_app_turbo_experimental(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       turbo: true,
       bundleType: 'app',
       experimental: true,
@@ -2891,9 +2891,9 @@ export async function next_bundle_app_turbo_experimental(task, opts) {
 }
 
 export async function next_bundle_app_prod_experimental(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       dev: false,
       bundleType: 'app',
       experimental: true,
@@ -2903,9 +2903,9 @@ export async function next_bundle_app_prod_experimental(task, opts) {
 }
 
 export async function next_bundle_app_dev_experimental(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       dev: true,
       bundleType: 'app',
       experimental: true,
@@ -2915,9 +2915,9 @@ export async function next_bundle_app_dev_experimental(task, opts) {
 }
 
 export async function next_bundle_pages_prod(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       dev: false,
       bundleType: 'pages',
     }),
@@ -2926,9 +2926,9 @@ export async function next_bundle_pages_prod(task, opts) {
 }
 
 export async function next_bundle_pages_dev(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       dev: true,
       bundleType: 'pages',
     }),
@@ -2937,9 +2937,9 @@ export async function next_bundle_pages_dev(task, opts) {
 }
 
 export async function next_bundle_pages_turbo(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       turbo: true,
       bundleType: 'pages',
     }),
@@ -2948,9 +2948,9 @@ export async function next_bundle_pages_turbo(task, opts) {
 }
 
 export async function next_bundle_server(task, opts) {
-  await task.source('dist').webpack({
+  await task.source('dist').rspack({
     watch: opts.dev,
-    config: require('./next-runtime.webpack-config')({
+    config: require('./next_runtime.config')({
       dev: false,
       bundleType: 'server',
     }),

packages/next/taskfile.js

@@ -1,7 +1,7 @@
 // Source: https://github.com/mondaychen/devtools-ignore-webpack-plugin/blob/e35ce41d9606a92a455ef247f509a1c2ccab5778/src/index.ts
 
 // eslint-disable-next-line import/no-extraneous-dependencies -- this is a dev-only file
-const webpack = require('webpack')
+const webpack = require('@rspack/core')
 
 // Following the naming conventions from
 // https://tc39.es/source-map/#source-map-format
@@ -28,12 +28,12 @@ module.exports = class DevToolsIgnorePlugin {
     }
   }
   apply(compiler) {
-    const { RawSource } = compiler.webpack.sources
+    const { RawSource } = webpack.sources
     compiler.hooks.compilation.tap(PLUGIN_NAME, (compilation) => {
       compilation.hooks.processAssets.tap(
         {
           name: PLUGIN_NAME,
-          stage: webpack.Compilation.PROCESS_ASSETS_STAGE_DEV_TOOLING,
+          stage: compilation.PROCESS_ASSETS_STAGE_DEV_TOOLING,
           additionalAssets: true,
         },
         (assets) => {