Add i18n items to routes manifest (#17893)

This adds the i18n config items to the routes-manifest so that they can accessed in the builder. This doesn't increment the routes-manifest version as existing value shapes haven't been modified and an additional non-breaking value is being added

x-ref: #17370

Author: ijjk

packages/next/build/index.ts

@@ -306,6 +306,15 @@ export default async function build(
       dataRouteRegex: string
       namedDataRouteRegex?: string
     }>
+    i18n?: {
+      locales: string[]
+      defaultLocale: string[]
+      domains: Array<{
+        domain: string
+        defaultLocale: string
+        locales: string[]
+      }>
+    }
   } = {
     version: 3,
     pages404: true,
@@ -325,6 +334,7 @@ export default async function build(
         }
       }),
     dataRoutes: [],
+    i18n: config.experimental.i18n || undefined,
   }
 
   await promises.mkdir(distDir, { recursive: true })

packages/next/export/index.ts

@@ -285,6 +285,12 @@ export default async function exportApp(
 
   const { i18n } = nextConfig.experimental
 
+  if (i18n && !options.buildExport) {
+    throw new Error(
+      `i18n support is not compatible with next export. See here for more info on deploying: https://nextjs.org/docs/deployment`
+    )
+  }
+
   // Start the rendering process
   const renderOpts = {
     dir,

test/integration/i18n-support/test/index.test.js

@@ -34,6 +34,31 @@ async function addDefaultLocaleCookie(browser) {
 }
 
 function runTests(isDev) {
+  if (!isDev) {
+    it('should add i18n config to routes-manifest', async () => {
+      const routesManifest = await fs.readJSON(
+        join(appDir, '.next/routes-manifest.json')
+      )
+
+      expect(routesManifest.i18n).toEqual({
+        locales: ['en-US', 'nl-NL', 'nl-BE', 'nl', 'fr-BE', 'fr', 'en'],
+        defaultLocale: 'en-US',
+        domains: [
+          {
+            http: true,
+            domain: 'example.be',
+            defaultLocale: 'nl-BE',
+          },
+          {
+            http: true,
+            domain: 'example.fr',
+            defaultLocale: 'fr',
+          },
+        ],
+      })
+    })
+  }
+
   it('should navigate with locale prop correctly', async () => {
     const browser = await webdriver(appPort, '/links?nextLocale=fr')
     await addDefaultLocaleCookie(browser)