Top-level root layout is computed twice

[joulev]

Verify canary release

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

Provide environment information

Operating System:
      Platform: darwin
      Arch: arm64
      Version: Darwin Kernel Version 22.5.0: Thu Jun  8 22:21:34 PDT 2023; root:xnu-8796.121.3~7/RELEASE_ARM64_T8112
    Binaries:
      Node: 20.3.1
      npm: 9.6.7
      Yarn: 1.22.19
      pnpm: 8.6.5
    Relevant Packages:
      next: 13.4.8-canary.14
      eslint-config-next: N/A
      react: 18.2.0
      react-dom: 18.2.0
      typescript: 5.1.3
    Next.js Config:
      output: N/A

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

App directory (appDir: true)

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

https://github.com/joulev/debug/tree/nextjs-root-layout-computed-twice-for-dynamic-routes

To Reproduce

• next build
• next start
• Navigate to /

Describe the Bug

The root layout is computed twice.

$ pnpm start

> test-rsc-with-mdx@0.1.0 start /Users/joulev/dev/www/debug
> next start

- ready started server on 0.0.0.0:3000, url: http://localhost:3000
Computing layout with incoming pathname: /
Computing layout with incoming pathname: /

Interestingly, that only happens to the top-level root layout (app/layout.tsx). If I add a directory in-between use something like

$ tree ./app       
app
└── (group)
    ├── layout.tsx
    └── page.tsx

2 directories, 2 files

then the (still root) layout is not computed twice.

Expected Behavior

The root layout should only be computed once, like the case where it is not exactly app/layout.tsx as shown above.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

next start

[izica]

nextjs v13.4.8 same bug

[balazsorban44]

Thanks, this is a duplicate of #49115 so I'm closing.

[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.