Optionally bundle legacy react-dom/server APIs based on usage

packages/next/src/build/create-compiler-aliases.ts

@@ -255,15 +255,14 @@ export function createRSCAliases(
     'react-dom/static$': `next/dist/compiled/react-dom-experimental/static`,
     'react-dom/static.edge$': `next/dist/compiled/react-dom-experimental/static.edge`,
     'react-dom/static.browser$': `next/dist/compiled/react-dom-experimental/static.browser`,
-    'react-dom/server.edge$': `next/dist/compiled/react-dom${bundledReactChannel}/server.edge`,
-    'react-dom/server.browser$': `next/dist/compiled/react-dom${bundledReactChannel}/server.browser`,
+    // optimizations to ignore the legacy build of react-dom/server in `server.browser` build
+    'react-dom/server.edge$': `next/dist/build/webpack/alias/react-dom-server-edge${bundledReactChannel}.js`,
+    'react-dom/server.browser$': `next/dist/build/webpack/alias/react-dom-server-browser${bundledReactChannel}.js`,
+    // react-server-dom-webpack alias
     'react-server-dom-webpack/client$': `next/dist/compiled/react-server-dom-webpack${bundledReactChannel}/client`,
     'react-server-dom-webpack/client.edge$': `next/dist/compiled/react-server-dom-webpack${bundledReactChannel}/client.edge`,
     'react-server-dom-webpack/server.edge$': `next/dist/compiled/react-server-dom-webpack${bundledReactChannel}/server.edge`,
     'react-server-dom-webpack/server.node$': `next/dist/compiled/react-server-dom-webpack${bundledReactChannel}/server.node`,
-    // optimisations to ignore the legacy build of react-dom/server
-    './cjs/react-dom-server-legacy.browser.production.min.js': `next/dist/build/noop-react-dom-server-legacy`,
-    './cjs/react-dom-server-legacy.browser.development.js': `next/dist/build/noop-react-dom-server-legacy`,
   }
 
   if (!isEdgeServer) {

packages/next/src/build/webpack/alias/react-dom-server-browser-experimental.js

@@ -0,0 +1,18 @@
+var l, s
+if (process.env.NODE_ENV === 'production') {
+  l = require('next/dist/compiled/react-dom-experimental/cjs/react-dom-server-legacy.browser.production.min.js')
+  s = require('next/dist/compiled/react-dom-experimental/cjs/react-dom-server.browser.production.min.js')
+} else {
+  l = require('next/dist/compiled/react-dom-experimental/cjs/react-dom-server-legacy.browser.development.js')
+  s = require('next/dist/compiled/react-dom-experimental/cjs/react-dom-server.browser.development.js')
+}
+
+exports.version = l.version
+exports.renderToString = l.renderToString
+exports.renderToStaticMarkup = l.renderToStaticMarkup
+exports.renderToNodeStream = l.renderToNodeStream
+exports.renderToStaticNodeStream = l.renderToStaticNodeStream
+exports.renderToReadableStream = s.renderToReadableStream
+if (s.resume) {
+  exports.resume = s.resume
+}

packages/next/src/build/webpack/alias/react-dom-server-browser.js

@@ -0,0 +1,18 @@
+var l, s
+if (process.env.NODE_ENV === 'production') {
+  l = require('next/dist/compiled/react-dom/cjs/react-dom-server-legacy.browser.production.min.js')
+  s = require('next/dist/compiled/react-dom/cjs/react-dom-server.browser.production.min.js')
+} else {
+  l = require('next/dist/compiled/react-dom/cjs/react-dom-server-legacy.browser.development.js')
+  s = require('next/dist/compiled/react-dom/cjs/react-dom-server.browser.development.js')
+}
+
+exports.version = l.version
+exports.renderToString = l.renderToString
+exports.renderToStaticMarkup = l.renderToStaticMarkup
+exports.renderToNodeStream = l.renderToNodeStream
+exports.renderToStaticNodeStream = l.renderToStaticNodeStream
+exports.renderToReadableStream = s.renderToReadableStream
+if (s.resume) {
+  exports.resume = s.resume
+}

packages/next/src/build/webpack/alias/react-dom-server-edge-experimental.js

@@ -0,0 +1,23 @@
+const ERROR_MESSAGE =
+  'Internal Error: do not use legacy react-dom/server APIs. If you encountered this error, please open an issue on the Next.js repo.'
+
+function error() {
+  throw new Error(ERROR_MESSAGE)
+}
+
+var b
+if (process.env.NODE_ENV === 'production') {
+  b = require('next/dist/compiled/react-dom-experimental/cjs/react-dom-server.edge.production.min.js')
+} else {
+  b = require('next/dist/compiled/react-dom-experimental/cjs/react-dom-server.edge.development.js')
+}
+
+exports.version = b.version
+exports.renderToReadableStream = b.renderToReadableStream
+exports.renderToNodeStream = b.renderToNodeStream
+exports.renderToStaticNodeStream = b.renderToStaticNodeStream
+exports.renderToString = error
+exports.renderToStaticMarkup = error
+if (b.resume) {
+  exports.resume = b.resume
+}

packages/next/src/build/webpack/alias/react-dom-server-edge.js

@@ -0,0 +1,23 @@
+const ERROR_MESSAGE =
+  'Internal Error: do not use legacy react-dom/server APIs. If you encountered this error, please open an issue on the Next.js repo.'
+
+function error() {
+  throw new Error(ERROR_MESSAGE)
+}
+
+var b
+if (process.env.NODE_ENV === 'production') {
+  b = require('next/dist/compiled/react-dom/cjs/react-dom-server.edge.production.min.js')
+} else {
+  b = require('next/dist/compiled/react-dom/cjs/react-dom-server.edge.development.js')
+}
+
+exports.version = b.version
+exports.renderToReadableStream = b.renderToReadableStream
+exports.renderToNodeStream = b.renderToNodeStream
+exports.renderToStaticNodeStream = b.renderToStaticNodeStream
+exports.renderToString = error
+exports.renderToStaticMarkup = error
+if (b.resume) {
+  exports.resume = b.resume
+}

packages/next/webpack.config.js

@@ -20,6 +20,15 @@ const pagesExternals = [
   'react-server-dom-webpack/server.node',
 ]
 
+const appExternals = [
+  // Externalize the react-dom/server legacy implementation outside of the runtime.
+  // If users are using them and imported from 'react-dom/server' they will get the external asset bundled.
+  'next/dist/compiled/react-dom/cjs/react-dom-server-legacy.browser.development.js',
+  'next/dist/compiled/react-dom/cjs/react-dom-server-legacy.browser.production.min.js',
+  'next/dist/compiled/react-dom-experimental/cjs/react-dom-server-legacy.browser.development.js',
+  'next/dist/compiled/react-dom-experimental/cjs/react-dom-server-legacy.browser.production.min.js',
+]
+
 function makeAppAliases(reactChannel = '') {
   return {
     react$: `next/dist/compiled/react${reactChannel}`,
@@ -30,11 +39,14 @@ function makeAppAliases(reactChannel = '') {
     'react/jsx-dev-runtime$': `next/dist/compiled/react${reactChannel}/jsx-dev-runtime`,
     'react-dom/client$': `next/dist/compiled/react-dom${reactChannel}/client`,
     'react-dom/server$': `next/dist/compiled/react-dom${reactChannel}/server`,
-    'react-dom/server.edge$': `next/dist/compiled/react-dom${reactChannel}/server.edge`,
-    'react-dom/server.browser$': `next/dist/compiled/react-dom${reactChannel}/server.browser`,
     'react-dom/static$': `next/dist/compiled/react-dom-experimental/static`,
     'react-dom/static.edge$': `next/dist/compiled/react-dom-experimental/static.edge`,
     'react-dom/static.browser$': `next/dist/compiled/react-dom-experimental/static.browser`,
+    // optimizations to ignore the legacy build of react-dom/server in `server.browser` build
+    'react-dom/server.edge$': `next/dist/build/webpack/alias/react-dom-server-edge${reactChannel}.js`,
+    // In Next.js runtime only use react-dom/server.edge
+    'react-dom/server.browser$': 'react-dom/server.edge',
+    // react-server-dom-webpack alias
     'react-server-dom-turbopack/client$': `next/dist/compiled/react-server-dom-turbopack${reactChannel}/client`,
     'react-server-dom-turbopack/client.edge$': `next/dist/compiled/react-server-dom-turbopack${reactChannel}/client.edge`,
     'react-server-dom-turbopack/server.edge$': `next/dist/compiled/react-server-dom-turbopack${reactChannel}/server.edge`,
@@ -43,9 +55,6 @@ function makeAppAliases(reactChannel = '') {
     'react-server-dom-webpack/client.edge$': `next/dist/compiled/react-server-dom-webpack${reactChannel}/client.edge`,
     'react-server-dom-webpack/server.edge$': `next/dist/compiled/react-server-dom-webpack${reactChannel}/server.edge`,
     'react-server-dom-webpack/server.node$': `next/dist/compiled/react-server-dom-webpack${reactChannel}/server.node`,
-    // optimisations to ignore the legacy build of react-dom/server
-    './cjs/react-dom-server-legacy.browser.production.min.js': `next/dist/build/noop-react-dom-server-legacy`,
-    './cjs/react-dom-server-legacy.browser.development.js': `next/dist/build/noop-react-dom-server-legacy`,
   }
 }
 
@@ -252,7 +261,7 @@ module.exports = ({ dev, turbo, bundleType, experimental }) => {
     },
     externals: [
       ...sharedExternals,
-      ...(bundleType === 'pages' ? pagesExternals : []),
+      ...(bundleType === 'pages' ? pagesExternals : appExternals),
       externalsMap,
       externalHandler,
     ],

test/e2e/app-dir/rsc-basic/app/app-react/client-react.js

@@ -3,15 +3,21 @@
 import React from 'react'
 import ReactDOM from 'react-dom'
 import ReactDOMServer from 'react-dom/server.edge'
+import { renderToStaticMarkup } from 'react-dom/server'
 
 export default function ClientReact() {
+  const markup = renderToStaticMarkup(
+    <div className="react-static-markup">{'React Static Markup'}</div>
+  )
+
   return (
     <div>
       <p id="client-react">{'React.version=' + React.version}</p>
       <p id="client-react-dom">{'ReactDOM.version=' + ReactDOM.version}</p>
       <p id="client-react-dom-server">
         {'ReactDOMServer.version=' + ReactDOMServer.version}
       </p>
+      <p id="markup">{markup}</p>
     </div>
   )
 }

test/e2e/app-dir/rsc-basic/rsc-basic.test.ts

@@ -544,6 +544,36 @@ createNextDescribe(
       )
     })
 
+    it('should be able to call legacy react-dom/server APIs in client components', async () => {
+      const $ = await next.render$('/app-react')
+      const content = $('#markup').text()
+      expect(content).toBe(
+        '<div class="react-static-markup">React Static Markup</div>'
+      )
+
+      if (isNextDev) {
+        const filePath = 'app/app-react/client-react.js'
+        const fileContent = await next.readFile(filePath)
+        await next.patchFile(
+          filePath,
+          fileContent.replace(
+            `import { renderToStaticMarkup } from 'react-dom/server'`,
+            `import { renderToStaticMarkup } from 'react-dom/server.browser'`
+          )
+        )
+
+        const browser = await next.browser('/app-react')
+        const markupContentInBrowser = await browser
+          .elementByCss('#markup')
+          .text()
+        expect(markupContentInBrowser).toBe(
+          '<div class="react-static-markup">React Static Markup</div>'
+        )
+
+        await next.patchFile(filePath, fileContent)
+      }
+    })
+
     // disable this flaky test
     it.skip('should support partial hydration with inlined server data in browser', async () => {
       // Should end up with "next_streaming_data".