Ensure external middleware rewrite is handled correctly

packages/next/shared/lib/router/router.ts

@@ -1853,7 +1853,15 @@ export default class Router implements BaseRouter {
       shouldCache: options.cache,
     })
 
-    if (preflight.rewrite?.startsWith('/')) {
+    if (preflight.rewrite) {
+      // for external rewrites we need to do a hard navigation
+      // to the resource
+      if (!preflight.rewrite.startsWith('/')) {
+        return {
+          type: 'redirect',
+          destination: options.as,
+        }
+      }
       const parsed = parseRelativeUrl(
         normalizeLocalePath(
           hasBasePath(preflight.rewrite)

test/integration/middleware/core/pages/rewrites/_middleware.js

@@ -6,6 +6,16 @@ import { NextResponse } from 'next/server'
 export async function middleware(request) {
   const url = request.nextUrl
 
+  if (
+    url.pathname.startsWith('/rewrites/about') &&
+    url.searchParams.has('override')
+  ) {
+    const isExternal = url.searchParams.get('override') === 'external'
+    return NextResponse.rewrite(
+      isExternal ? 'https://example.com' : '/rewrites/a'
+    )
+  }
+
   if (url.pathname.startsWith('/rewrites/to-blog')) {
     const slug = url.pathname.split('/').pop()
     url.pathname = `/rewrites/fallback-true-blog/${slug}`

test/integration/middleware/core/pages/rewrites/index.js

@@ -24,6 +24,14 @@ export default function Home() {
       <Link href="/rewrites/rewrite-me-without-hard-navigation?message=refreshed">
         <a id="link-with-rewritten-url">Rewrite me without a hard navigation</a>
       </Link>
+      <div />
+      <Link href="/rewrites/about?override=external">
+        <a id="override-with-external-rewrite">Rewrite me to external site</a>
+      </Link>
+      <div />
+      <Link href="/rewrites/about?override=internal">
+        <a id="override-with-internal-rewrite">Rewrite me to internal path</a>
+      </Link>
     </div>
   )
 }

test/integration/middleware/core/test/index.test.js

@@ -162,6 +162,56 @@ function urlTests(log, locale = '') {
 }
 
 function rewriteTests(log, locale = '') {
+  it('should override with rewrite internally correctly', async () => {
+    const res = await fetchViaHTTP(
+      context.appPort,
+      '/rewrites/about',
+      { override: 'internal' },
+      { redirect: 'manual' }
+    )
+
+    expect(res.status).toBe(200)
+    expect(await res.text()).toContain('Welcome Page A')
+
+    const browser = await webdriver(context.appPort, `${locale}/rewrites`)
+    await browser.elementByCss('#override-with-internal-rewrite').click()
+    await check(
+      () => browser.eval('document.documentElement.innerHTML'),
+      /Welcome Page A/
+    )
+    expect(await browser.eval('window.location.pathname')).toBe(
+      `${locale || ''}/rewrites/about`
+    )
+    expect(await browser.eval('window.location.search')).toBe(
+      '?override=internal'
+    )
+  })
+
+  it('should override with rewrite externally correctly', async () => {
+    const res = await fetchViaHTTP(
+      context.appPort,
+      '/rewrites/about',
+      { override: 'external' },
+      { redirect: 'manual' }
+    )
+
+    expect(res.status).toBe(200)
+    expect(await res.text()).toContain('Example Domain')
+
+    const browser = await webdriver(context.appPort, `${locale}/rewrites`)
+    await browser.elementByCss('#override-with-external-rewrite').click()
+    await check(
+      () => browser.eval('document.documentElement.innerHTML'),
+      /Example Domain/
+    )
+    expect(await browser.eval('window.location.pathname')).toBe(
+      `${locale || ''}/rewrites/about`
+    )
+    expect(await browser.eval('window.location.search')).toBe(
+      '?override=external'
+    )
+  })
+
   it('should rewrite to fallback: true page successfully', async () => {
     const randomSlug = `another-${Date.now()}`
     const res2 = await fetchViaHTTP(