Emit late streaming meta tags

packages/next/src/server/app-render/index.tsx

@@ -1704,7 +1704,35 @@ export async function renderToHTMLOrFlight(
         )
 
         let polyfillsFlushed = false
-        const getServerInsertedHTML = (): Promise<string> => {
+        let flushedErrorMetaTagsUntilIndex = 0
+        const getServerInsertedHTML = () => {
+          // Loop through all the errors that have been captured but not yet
+          // flushed.
+          const errorMetaTags = []
+          for (
+            ;
+            flushedErrorMetaTagsUntilIndex < allCapturedErrors.length;
+            flushedErrorMetaTagsUntilIndex++
+          ) {
+            const error = allCapturedErrors[flushedErrorMetaTagsUntilIndex]
+            if (isNotFoundError(error)) {
+              errorMetaTags.push(
+                <meta name="robots" content="noindex" key={error.digest} />
+              )
+            } else if (isRedirectError(error)) {
+              const redirectUrl = getURLFromRedirectError(error)
+              if (redirectUrl) {
+                errorMetaTags.push(
+                  <meta
+                    httpEquiv="refresh"
+                    content={`0;url=${redirectUrl}`}
+                    key={error.digest}
+                  />
+                )
+              }
+            }
+          }
+
           const flushed = renderToString(
             <>
               {Array.from(serverInsertedHTMLCallbacks).map((callback) =>
@@ -1723,6 +1751,7 @@ export async function renderToHTMLOrFlight(
                       />
                     )
                   })}
+              {errorMetaTags}
             </>
           )
           polyfillsFlushed = true

test/e2e/app-dir/navigation/app/redirect/suspense/page.js

@@ -0,0 +1,41 @@
+import { Suspense } from 'react'
+import { redirect } from 'next/navigation'
+
+function createSuspenseyComponent(Component, { timeout = 0, expire = 10 }) {
+  let result
+  let promise
+  return function Data() {
+    if (result) return result
+    if (!promise)
+      promise = new Promise((resolve) => {
+        setTimeout(() => {
+          result = <Component />
+          setTimeout(() => {
+            result = undefined
+            promise = undefined
+          }, expire)
+          resolve()
+        }, timeout)
+      })
+    throw promise
+  }
+}
+
+function Redirect() {
+  redirect('/redirect/result')
+  return <></>
+}
+
+const SuspenseyRedirect = createSuspenseyComponent(Redirect, {
+  timeout: 300,
+})
+
+export default function () {
+  return (
+    <div className="suspense">
+      <Suspense fallback="fallback">
+        <SuspenseyRedirect />
+      </Suspense>
+    </div>
+  )
+}

test/e2e/app-dir/navigation/navigation.test.ts

@@ -105,9 +105,6 @@ createNextDescribe(
         ).toBe('noindex')
       })
       it('should trigger not-found while streaming', async () => {
-        const initialHtml = await next.render('/not-found/suspense')
-        expect(initialHtml).not.toContain('noindex')
-
         const browser = await next.browser('/not-found/suspense')
         expect(
           await browser.waitForElementByCss('#not-found-component').text()
@@ -261,5 +258,19 @@ createNextDescribe(
         }
       })
     })
+
+    describe('SEO', () => {
+      it('should emit noindex meta tag for not found page when streaming', async () => {
+        const html = await next.render('/not-found/suspense')
+        expect(html).toContain('<meta name="robots" content="noindex"/>')
+      })
+
+      it('should emit refresh meta tag for redirect page when streaming', async () => {
+        const html = await next.render('/redirect/suspense')
+        expect(html).toContain(
+          '<meta http-equiv="refresh" content="0;url=/redirect/result"/>'
+        )
+      })
+    })
   }
 )