sitemap.ts marked as as "use client" in version 13.4.9

[Svish]

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
      Platform: win32
      Arch: x64
      Version: Windows 10 Pro
    Binaries:
      Node: 20.1.0
      npm: N/A
      Yarn: N/A
      pnpm: N/A
    Relevant Packages:
      next: 13.4.8
      eslint-config-next: 13.4.9
      react: 18.2.0
      react-dom: 18.2.0
      typescript: 5.1.6
    Next.js Config:
      output: N/A

Which area(s) of Next.js are affected? (leave empty if unsure)

App Router

Link to the code that reproduces this issue or a replay of the bug

https://github.com/Svish/geekality.net/tree/e1a6cda84d9c3bd1879f405f96c616102fdeee8a

To Reproduce

1. Run npm i next@13.4.9 (or .10-canary.0)
2. Use import 'server-only' in a file that's imported by ./src/app/sitemap.ts.
3. Run npm run build

Describe the Bug

I have a file that uses import 'server-only' to make sure it doesn't leak into client components. In version 13.4.8 this was working fine, but once I tried to update next to the current 13.4.9, I'm suddenly getting an error because of this. And the weirder part is that the error seem to be coming from my ./src/app/sitemap.ts, which is definitely not using any client components, it's actually not using any components at all. It's the metadata route for sitemaps from Next. 🤔

Here's the output from running npm run build on version 13.4.9. The latest canary produces the same error:

- warn You have enabled experimental feature (typedRoutes) in next.config.js.
- warn Experimental features are not covered by semver, and may cause unexpected or broken application behavior. 
Use at your own risk.

Warning: Contentlayer might not work as expected on Windows
Generated 269 documents in .contentlayer
Failed to compile.

./src\content\index.ts
ReactServerComponentsError:

You're importing a component that needs server-only. That only works in a Server Component but one of its parents is marked with "use client", so it's a Client Component.
Learn more: https://nextjs.org/docs/getting-started/react-essentials

   ╭─[D:\projects\geekality.net\src\content\index.ts:1:1]
 1 │ import 'server-only'
   · ────────────────────
 2 │
 3 │ import { byString, byStringValue } from '@/util/sort'
 4 │ import { onlyPublished } from './filters'
   ╰────

One of these is marked as a client entry with "use client":
  ./src\content\index.ts
  ./src\app\sitemap.ts
  ./src\app\sitemap.ts


> Build failed because of webpack errors
- info Creating an optimized production build .

Expected Behavior

The import 'server-only' in my ./src/content/index.ts shouldn't cause any issues in sitemap.ts, or any other files for that matter, just because I update next to version 13.4.9.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

_NEXT-1417

[Arctomachine]

It started happening at canary 2, so one of commits between 1 and 2 causes this.
v13.4.9-canary.1...v13.4.9-canary.2

[timneutkens]

Looking at the diff it's caused by this change: #51950

[franzwarning]

Seeing this same error with my icon.tsx file which is exporting a default async function which is getting headers from next/headers. I get the error:

You're importing a component that needs next/headers. That only works in a Server Component but one of its parents is marked with "use client", so it's a Client Component.

None of the parents are client components. It looks like the fix you pushed is only for those marked w/ server-only?

[huozhi]

@franzwarning The fix is landed on latest canary, please upgrade to canary. The server-only marked it's works with server components hooks, so next/headers should work with that as well after the fix.

[github-actions]

This closed issue has been automatically locked because it had no new activity for a month. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.