Update to handle correct react version with app

packages/next/build/index.ts

@@ -120,6 +120,7 @@ import { RemotePattern } from '../shared/lib/image-config'
 import { eventSwcPlugins } from '../telemetry/events/swc-plugins'
 import { normalizeAppPath } from '../shared/lib/router/utils/app-paths'
 import { AppBuildManifest } from './webpack/plugins/app-build-manifest-plugin'
+import { verifyAppReactVersion } from '../lib/verifyAppReactVersion'
 
 export type SsgRoute = {
   initialRevalidateSeconds: number | false
@@ -307,6 +308,9 @@ export default async function build(
       }
       const { pagesDir, appDir } = findPagesDir(dir, isAppDirEnabled)
 
+      if (isAppDirEnabled) {
+        await verifyAppReactVersion({ dir })
+      }
       const hasPublicDir = await fileExists(publicDir)
 
       telemetry.record(

packages/next/lib/verifyAppReactVersion.ts

@@ -0,0 +1,122 @@
+import chalk from 'next/dist/compiled/chalk'
+
+import {
+  hasNecessaryDependencies,
+  MissingDependency,
+  NecessaryDependencies,
+} from './has-necessary-dependencies'
+
+import { installDependencies } from './install-dependencies'
+import { isCI } from '../telemetry/ci-info'
+import { FatalError } from './fatal-error'
+import { getPkgManager } from './helpers/get-pkg-manager'
+import { getOxfordCommaList } from './oxford-comma-list'
+const requiredReactVersion = process.env.REQUIRED_APP_REACT_VERSION || ''
+
+const removalMsg =
+  '\n\n' +
+  chalk.bold(
+    'If you are not trying to use the `app` directory, please disable the ' +
+      chalk.cyan('experimental.appDir') +
+      ' config in your `next.config.js`.'
+  )
+
+const requiredPackages = [
+  {
+    file: 'react/index.js',
+    pkg: 'react',
+    exportsRestrict: true,
+  },
+  {
+    file: 'react-dom/index.js',
+    pkg: 'react-dom',
+    exportsRestrict: true,
+  },
+]
+
+async function missingDepsError(
+  dir: string,
+  missingPackages: MissingDependency[]
+) {
+  const packagesHuman = getOxfordCommaList(missingPackages.map((p) => p.pkg))
+  const packagesCli = missingPackages
+    .map((p) => `${p.pkg}@${requiredReactVersion}`)
+    .join(' ')
+  const packageManager = getPkgManager(dir)
+
+  throw new FatalError(
+    chalk.bold.red(
+      `It looks like you're trying to use the \`app\` directory but do not have the required react version installed.`
+    ) +
+      '\n\n' +
+      chalk.bold(`Please install ${chalk.bold(packagesHuman)} by running:`) +
+      '\n\n' +
+      `\t${chalk.bold.cyan(
+        (packageManager === 'yarn'
+          ? 'yarn add --dev'
+          : packageManager === 'pnpm'
+          ? 'pnpm install --save-dev'
+          : 'npm install --save-dev') +
+          ' ' +
+          packagesCli
+      )}` +
+      removalMsg +
+      '\n'
+  )
+}
+
+export async function verifyAppReactVersion({
+  dir,
+}: {
+  dir: string
+}): Promise<void> {
+  if (process.env.NEXT_SKIP_APP_REACT_INSTALL) {
+    return
+  }
+
+  // Ensure TypeScript and necessary `@types/*` are installed:
+  let deps: NecessaryDependencies = await hasNecessaryDependencies(
+    dir,
+    requiredPackages
+  )
+  const resolvedReact = deps.resolved.get('react')
+  const installedVersion =
+    resolvedReact &&
+    require(deps.resolved.get('react') || '')
+      .version?.split('-experimental')
+      .pop()
+
+  if (
+    deps.missing?.length ||
+    installedVersion !== requiredReactVersion.split('-experimental').pop()
+  ) {
+    const neededDeps = requiredPackages.map((dep) => {
+      dep.pkg = `${dep.pkg}@${requiredReactVersion}`
+      return dep
+    })
+
+    if (isCI) {
+      // we don't attempt auto install in CI to avoid side-effects
+      // and instead log the error for installing needed packages
+      await missingDepsError(dir, neededDeps)
+    }
+    console.log(
+      chalk.bold.yellow(
+        `It looks like you're trying to use \`app\` directory but do not have the required react version installed.`
+      ) +
+        '\n' +
+        removalMsg +
+        '\n'
+    )
+    await installDependencies(dir, neededDeps, true).catch((err) => {
+      if (err && typeof err === 'object' && 'command' in err) {
+        console.error(
+          `\nFailed to install required react versions, please install them manually to continue:\n` +
+            (err as any).command +
+            '\n'
+        )
+      }
+      process.exit(1)
+    })
+  }
+}

packages/next/server/dev/next-dev-server.ts

@@ -76,6 +76,7 @@ import {
 } from '../../build/utils'
 import { getDefineEnv } from '../../build/webpack-config'
 import loadJsConfig from '../../build/load-jsconfig'
+import { verifyAppReactVersion } from '../../lib/verifyAppReactVersion'
 
 // Load ReactDevOverlay only when needed
 let ReactDevOverlayImpl: FunctionComponent
@@ -658,6 +659,10 @@ export default class DevServer extends Server {
     setGlobal('distDir', this.distDir)
     setGlobal('phase', PHASE_DEVELOPMENT_SERVER)
 
+    if (this.hasAppDir) {
+      await verifyAppReactVersion({ dir: this.dir })
+    }
+
     await this.verifyTypeScript()
     this.customRoutes = await loadCustomRoutes(this.nextConfig)
 

packages/next/taskfile-swc.js

@@ -156,8 +156,17 @@ if ((typeof exports.default === 'function' || (typeof exports.default === 'objec
 }
 
 function setNextVersion(code) {
-  return code.replace(
-    /process\.env\.__NEXT_VERSION/g,
-    `"${require('./package.json').version}"`
-  )
+  return code
+    .replace(
+      /process\.env\.__NEXT_VERSION/g,
+      `"${require('./package.json').version}"`
+    )
+    .replace(
+      /process\.env\.REQUIRED_APP_REACT_VERSION/,
+      `"${
+        require('../../package.json').devDependencies[
+          'react-server-dom-webpack'
+        ]
+      }"`
+    )
 }

test/.stats-app/package.json

@@ -4,7 +4,7 @@
   "license": "MIT",
   "dependencies": {
     "next": "latest",
-    "react": "0.0.0-experimental-cb5084d1c-20220924",
-    "react-dom": "0.0.0-experimental-cb5084d1c-20220924"
+    "react": "0.0.0-experimental-9cdf8a99e-20221018",
+    "react-dom": "0.0.0-experimental-9cdf8a99e-20221018"
   }
 }

test/integration/conflicting-app-page-error/test/index.test.js

@@ -8,7 +8,11 @@ const appDir = path.join(__dirname, '..')
 describe('conflict between app file and page file', () => {
   it('errors during build', async () => {
     const conflicts = ['/hello', '/another']
-    const results = await nextBuild(appDir, [], { stdout: true, stderr: true })
+    const results = await nextBuild(appDir, [], {
+      stdout: true,
+      stderr: true,
+      env: { NEXT_SKIP_APP_REACT_INSTALL: '1' },
+    })
     const output = results.stdout + results.stderr
     expect(output).toMatch(/Conflicting app and page files were found/)