Fix GSP redirect cache error (vercel#26627)

This makes sure we don't attempt flushing cache info to disk for `getStaticProps` `redirect` items with `revalidate`

Fixes: vercel#20816

## Bug

- [x] Related issues linked using `fixes #number`
- [x] Integration tests added

Author: ijjk

packages/next/next-server/server/incremental-cache.ts

@@ -194,7 +194,11 @@ export class IncrementalCache {
 
     // TODO: This option needs to cease to exist unless it stops mutating the
     // `next build` output's manifest.
-    if (this.incrementalOptions.flushToDisk && !data.isNotFound) {
+    if (
+      this.incrementalOptions.flushToDisk &&
+      !data.isNotFound &&
+      !data.isRedirect
+    ) {
       try {
         const seedPath = this.getSeedPath(pathname, 'html')
         await promises.mkdir(path.dirname(seedPath), { recursive: true })

test/integration/gssp-redirect/pages/gsp-blog-blocking/[post].js

@@ -0,0 +1,86 @@
+import { useRouter } from 'next/router'
+
+export default function Post(props) {
+  const router = useRouter()
+
+  if (typeof window === 'undefined') {
+    if (router.query.post?.startsWith('redir')) {
+      console.log(router)
+      throw new Error('render should not occur for redirect')
+    }
+  }
+
+  if (typeof window !== 'undefined' && !window.initialHref) {
+    window.initialHref = window.location.href
+  }
+
+  if (router.isFallback) return <p>Loading...</p>
+
+  return (
+    <>
+      <p id="gsp">getStaticProps</p>
+      <p id="props">{JSON.stringify(props)}</p>
+    </>
+  )
+}
+
+export const getStaticProps = ({ params }) => {
+  if (params.post.startsWith('redir')) {
+    let destination = '/404'
+
+    if (params.post.includes('dest-external')) {
+      destination = 'https://example.com'
+    } else if (params.post.includes('dest-')) {
+      destination = params.post.split('dest-').pop().replace(/_/g, '/')
+    }
+
+    let permanent = undefined
+    let statusCode = undefined
+
+    if (params.post.includes('statusCode-')) {
+      permanent = parseInt(
+        params.post.split('statusCode-').pop().split('-').shift(),
+        10
+      )
+    }
+
+    if (params.post.includes('permanent')) {
+      permanent = true
+    } else if (!statusCode) {
+      permanent = false
+    }
+    let revalidate
+
+    if (params.post.includes('revalidate-')) {
+      revalidate = 1
+    }
+    console.log('redirecting', {
+      destination,
+      permanent,
+      statusCode,
+      revalidate,
+    })
+
+    return {
+      redirect: {
+        destination,
+        permanent,
+        statusCode,
+      },
+      revalidate,
+    }
+  }
+
+  return {
+    props: {
+      params,
+    },
+  }
+}
+
+export const getStaticPaths = () => {
+  return {
+    paths: ['first', 'second'].map((post) => ({ params: { post } })),
+    fallback: 'blocking',
+  }
+}

test/integration/gssp-redirect/pages/gsp-blog/[post].js

@@ -49,13 +49,25 @@ export const getStaticProps = ({ params }) => {
     } else if (!statusCode) {
       permanent = false
     }
+    let revalidate
+
+    if (params.post.includes('revalidate-')) {
+      revalidate = 1
+    }
+    console.log('redirecting', {
+      destination,
+      permanent,
+      statusCode,
+      revalidate,
+    })
 
     return {
       redirect: {
         destination,
         permanent,
         statusCode,
       },
+      revalidate,
     }
   }
 

test/integration/gssp-redirect/test/index.test.js

@@ -110,6 +110,90 @@ const runTests = (isDev) => {
     expect(pathname).toBe('/gsp-blog/redirect-dest-_gsp-blog_first')
   })
 
+  it('should apply redirect when fallback blocking GSP page is visited directly (internal dynamic)', async () => {
+    const browser = await webdriver(
+      appPort,
+      '/gsp-blog-blocking/redirect-dest-_gsp-blog_first',
+      true,
+      true
+    )
+
+    await browser.waitForElementByCss('#gsp')
+
+    const props = JSON.parse(await browser.elementByCss('#props').text())
+    expect(props).toEqual({
+      params: {
+        post: 'first',
+      },
+    })
+    const initialHref = await browser.eval(() => window.initialHref)
+    const { pathname } = url.parse(initialHref)
+    expect(pathname).toBe('/gsp-blog/first')
+  })
+
+  it('should apply redirect when fallback blocking GSP page is visited directly (internal dynamic) second visit', async () => {
+    const browser = await webdriver(
+      appPort,
+      '/gsp-blog-blocking/redirect-dest-_gsp-blog_first',
+      true,
+      true
+    )
+
+    await browser.waitForElementByCss('#gsp')
+
+    const props = JSON.parse(await browser.elementByCss('#props').text())
+    expect(props).toEqual({
+      params: {
+        post: 'first',
+      },
+    })
+    const initialHref = await browser.eval(() => window.initialHref)
+    const { pathname } = url.parse(initialHref)
+    expect(pathname).toBe('/gsp-blog/first')
+  })
+
+  it('should apply redirect when fallback blocking GSP page is visited directly (internal dynamic) with revalidate', async () => {
+    const browser = await webdriver(
+      appPort,
+      '/gsp-blog-blocking/redirect-revalidate-dest-_gsp-blog_first',
+      true,
+      true
+    )
+
+    await browser.waitForElementByCss('#gsp')
+
+    const props = JSON.parse(await browser.elementByCss('#props').text())
+    expect(props).toEqual({
+      params: {
+        post: 'first',
+      },
+    })
+    const initialHref = await browser.eval(() => window.initialHref)
+    const { pathname } = url.parse(initialHref)
+    expect(pathname).toBe('/gsp-blog/first')
+  })
+
+  it('should apply redirect when fallback blocking GSP page is visited directly (internal dynamic) with revalidate second visit', async () => {
+    const browser = await webdriver(
+      appPort,
+      '/gsp-blog-blocking/redirect-revalidate-dest-_gsp-blog_first',
+      true,
+      true
+    )
+
+    await browser.waitForElementByCss('#gsp')
+
+    const props = JSON.parse(await browser.elementByCss('#props').text())
+    expect(props).toEqual({
+      params: {
+        post: 'first',
+      },
+    })
+    const initialHref = await browser.eval(() => window.initialHref)
+    const { pathname } = url.parse(initialHref)
+    expect(pathname).toBe('/gsp-blog/first')
+  })
+
   if (!isDev) {
     it('should apply redirect when fallback GSP page is visited directly (internal dynamic) 2nd visit', async () => {
       const browser = await webdriver(
@@ -435,15 +519,28 @@ describe('GS(S)P Redirect Support', () => {
   })
 
   describe('production mode', () => {
+    let output = ''
+
     beforeAll(async () => {
       await fs.remove(join(appDir, '.next'))
       await nextBuild(appDir)
       appPort = await findPort()
-      app = await nextStart(appDir, appPort)
+      app = await nextStart(appDir, appPort, {
+        onStdout(msg) {
+          output += msg
+        },
+        onStderr(msg) {
+          output += msg
+        },
+      })
     })
     afterAll(() => killApp(app))
 
     runTests()
+
+    it('should not have errors in output', async () => {
+      expect(output).not.toContain('Failed to update prerender files')
+    })
   })
 
   describe('serverless mode', () => {