Repository: vercel/next.js
Pull request: fix: alternate bundler support for dropping client pages in AMP

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Fix failing tests for in DropClientPages mode for alternative bundler

Changed files:
filename: packages/next/src/build/webpack-config.ts
patch: @@ -1944,7 +1944,7 @@ export default async function getBaseWebpackConfig(
           dev,
         }),
       // rspack doesn't support the parser hooks used here
-      !isRspack && (isClient || isEdgeServer) && new DropClientPage(),
+      (isClient || isEdgeServer) && new DropClientPage(),
       isNodeServer &&
         !dev &&
         new (require('./webpack/plugins/next-trace-entrypoints-plugin')

filename: packages/next/src/build/webpack/plugins/next-drop-client-page-plugin.ts
patch: @@ -1,5 +1,6 @@
 import type { webpack } from 'next/dist/compiled/webpack/webpack'
 import { STRING_LITERAL_DROP_BUNDLE } from '../../../shared/lib/constants'
+import { extname } from 'path'
 
 export const ampFirstEntryNamesMap: WeakMap<webpack.Compilation, string[]> =
   new WeakMap()
@@ -8,9 +9,36 @@ const PLUGIN_NAME = 'DropAmpFirstPagesPlugin'
 
 // Prevents outputting client pages when they are not needed
 export class DropClientPage implements webpack.WebpackPluginInstance {
-  ampPages = new Set()
+  ampPages = new Set<string>()
 
   apply(compiler: webpack.Compiler) {
+    const isRspack = !!(compiler as any).rspack
+
+    if (isRspack) {
+      // For Rspack, use a simpler emit hook-based approach
+      compiler.hooks.emit.tap(PLUGIN_NAME, (compilation: any) => {
+        Object.keys(compilation.assets).forEach((assetKey) => {
+          const asset = compilation.assets[assetKey]
+
+          if (asset?._value?.includes?.(STRING_LITERAL_DROP_BUNDLE)) {
+            const cleanAssetKey = assetKey.replace(/\\/g, '/')
+            const page = '/' + cleanAssetKey.split('pages/')[1]
+            const pageNoExt = page.split(extname(page))[0]
+
+            delete compilation.assets[assetKey]
+
+            // Detect being re-ran through a child compiler and don't re-mark the
+            // page as AMP
+            if (!pageNoExt.endsWith('.module')) {
+              this.ampPages.add(pageNoExt.replace(/\/index$/, '') || '/')
+            }
+          }
+        })
+      })
+
+      return
+    }
+
     compiler.hooks.compilation.tap(
       PLUGIN_NAME,
       (compilation: any, { normalModuleFactory }: any) => {
@@ -39,6 +67,7 @@ export class DropClientPage implements webpack.WebpackPluginInstance {
             }
 
             // @ts-ignore buildInfo exists on Module
+            entryModule.buildInfo = entryModule.buildInfo || {}
             entryModule.buildInfo.NEXT_ampFirst = true
           }