Fix react packages are not bundled for metadata routes (#55579)

`isAppLayer` condition was missing `app-metadata-route` layer, made it
as a util now like other webpack layer utils, add metadata route layer
to the group. Then `React.cache` can be available there.

Also update regex to be compatible across platform

Fixes #55561 
Closes NEXT-1635

packages/next/src/build/utils.ts

@@ -2131,3 +2131,9 @@ export function isWebpackDefaultLayer(
 ): boolean {
   return layer === null || layer === undefined
 }
+
+export function isWebpackAppLayer(
+  layer: WebpackLayerName | null | undefined
+): boolean {
+  return Boolean(layer && WEBPACK_LAYERS.GROUP.app.includes(layer as any))
+}

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

@@ -19,7 +19,11 @@ import {
   WEBPACK_RESOURCE_QUERIES,
   WebpackLayerName,
 } from '../lib/constants'
-import { isWebpackDefaultLayer, isWebpackServerLayer } from './utils'
+import {
+  isWebpackAppLayer,
+  isWebpackDefaultLayer,
+  isWebpackServerLayer,
+} from './utils'
 import { CustomRoutes } from '../lib/load-custom-routes.js'
 import { isEdgeRuntime } from '../lib/is-edge-runtime'
 import {
@@ -412,7 +416,7 @@ function createRSCAliases(
   }
 
   if (!opts.isEdgeServer) {
-    if (opts.layer === 'ssr') {
+    if (opts.layer === WEBPACK_LAYERS.serverSideRendering) {
       alias = Object.assign(alias, {
         'react/jsx-runtime$': `next/dist/server/future/route-modules/app-page/vendored/shared/react-jsx-runtime`,
         'react/jsx-dev-runtime$': `next/dist/server/future/route-modules/app-page/vendored/shared/react-jsx-dev-runtime`,
@@ -421,7 +425,7 @@ function createRSCAliases(
         'react-dom/server.edge$': `next/dist/server/future/route-modules/app-page/vendored/${opts.layer}/react-dom-server-edge`,
         'react-server-dom-webpack/client.edge$': `next/dist/server/future/route-modules/app-page/vendored/${opts.layer}/react-server-dom-webpack-client-edge`,
       })
-    } else if (opts.layer === 'rsc') {
+    } else if (opts.layer === WEBPACK_LAYERS.reactServerComponents) {
       alias = Object.assign(alias, {
         'react/jsx-runtime$': `next/dist/server/future/route-modules/app-page/vendored/shared/react-jsx-runtime`,
         'react/jsx-dev-runtime$': `next/dist/server/future/route-modules/app-page/vendored/shared/react-jsx-dev-runtime`,
@@ -434,7 +438,7 @@ function createRSCAliases(
   }
 
   if (opts.isEdgeServer) {
-    if (opts.layer === 'rsc') {
+    if (opts.layer === WEBPACK_LAYERS.reactServerComponents) {
       alias[
         'react$'
       ] = `next/dist/compiled/react${bundledReactChannel}/react.shared-subset`
@@ -1383,15 +1387,7 @@ export default async function getBaseWebpackConfig(
       return `commonjs next/dist/lib/import-next-warning`
     }
 
-    const isAppLayer = (
-      [
-        WEBPACK_LAYERS.reactServerComponents,
-        WEBPACK_LAYERS.serverSideRendering,
-        WEBPACK_LAYERS.appPagesBrowser,
-        WEBPACK_LAYERS.actionBrowser,
-        WEBPACK_LAYERS.appRouteHandler,
-      ] as WebpackLayerName[]
-    ).includes(layer!)
+    const isAppLayer = isWebpackAppLayer(layer)
 
     // Relative requires don't need custom resolution, because they
     // are relative to requests we've already resolved here.
@@ -1461,25 +1457,30 @@ export default async function getBaseWebpackConfig(
     // Specific Next.js imports that should remain external
     // TODO-APP: Investigate if we can remove this.
     if (request.startsWith('next/dist/')) {
+      // Non external that needs to be transpiled
       // Image loader needs to be transpiled
-      if (/^next\/dist\/shared\/lib\/image-loader/.test(request)) {
+      if (/^next[\\/]dist[\\/]shared[\\/]lib[\\/]image-loader/.test(request)) {
         return
       }
 
-      if (/^next\/dist\/compiled\/next-server/.test(request)) {
+      if (/^next[\\/]dist[\\/]compiled[\\/]next-server/.test(request)) {
         return `commonjs ${request}`
       }
 
       if (
-        /^next\/dist\/shared\/(?!lib\/router\/router)/.test(request) ||
-        /^next\/dist\/compiled\/.*\.c?js$/.test(request)
+        /^next[\\/]dist[\\/]shared[\\/](?!lib[\\/]router[\\/]router)/.test(
+          request
+        ) ||
+        /^next[\\/]dist[\\/]compiled[\\/].*\.c?js$/.test(request)
       ) {
         return `commonjs ${request}`
       }
 
       if (
-        /^next\/dist\/esm\/shared\/(?!lib\/router\/router)/.test(request) ||
-        /^next\/dist\/compiled\/.*\.mjs$/.test(request)
+        /^next[\\/]dist[\\/]esm[\\/]shared[\\/](?!lib[\\/]router[\\/]router)/.test(
+          request
+        ) ||
+        /^next[\\/]dist[\\/]compiled[\\/].*\.mjs$/.test(request)
       ) {
         return `module ${request}`
       }

packages/next/src/lib/constants.ts

@@ -107,7 +107,7 @@ const WEBPACK_LAYERS_NAMES = {
    */
   reactServerComponents: 'rsc',
   /**
-   * Server Side Rendering layer (ssr).
+   * Server Side Rendering layer for app (ssr).
    */
   serverSideRendering: 'ssr',
   /**
@@ -157,6 +157,14 @@ const WEBPACK_LAYERS = {
       WEBPACK_LAYERS_NAMES.middleware,
       WEBPACK_LAYERS_NAMES.api,
     ],
+    app: [
+      WEBPACK_LAYERS_NAMES.reactServerComponents,
+      WEBPACK_LAYERS_NAMES.actionBrowser,
+      WEBPACK_LAYERS_NAMES.appMetadataRoute,
+      WEBPACK_LAYERS_NAMES.appRouteHandler,
+      WEBPACK_LAYERS_NAMES.serverSideRendering,
+      WEBPACK_LAYERS_NAMES.appPagesBrowser,
+    ],
   },
 }
 

test/e2e/app-dir/metadata-dynamic-routes/app/client-ref-dependency/client-component.tsx

@@ -0,0 +1,10 @@
+'use client'
+
+import React from 'react'
+
+function ClientComponent() {
+  const [state] = React.useState('component')
+  return <div>{`client-` + state}</div>
+}
+
+export const clientRef = <ClientComponent />

test/e2e/app-dir/metadata-dynamic-routes/app/client-ref-dependency/sitemap.tsx

@@ -0,0 +1,16 @@
+import React from 'react'
+import { clientRef } from './client-component'
+
+export const contentType = 'image/png'
+const cachedNoop = React.cache(() => null)
+
+function noopCall(value) {
+  return value
+}
+
+export default function sitemap() {
+  // keep the variable from being tree-shaken
+  noopCall(clientRef)
+  cachedNoop()
+  return []
+}

test/e2e/app-dir/metadata-dynamic-routes/index.test.ts

@@ -66,6 +66,13 @@ createNextDescribe(
           "
         `)
       })
+
+      it('should not throw if client components are imported but not used', async () => {
+        const { status } = await next.fetch(
+          '/client-ref-dependency/sitemap.xml'
+        )
+        expect(status).toBe(200)
+      })
     })
 
     describe('social image routes', () => {