__NEXT_MANGLING_DEBUG resp. --no-mangling do not work with swcMinify: true (per next config)

[dbo]

Verify canary release

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

Provide environment information

Operating System:
      Platform: darwin
      Arch: x64
      Version: Darwin Kernel Version 22.5.0: Mon Apr 24 20:51:50 PDT 2023; root:xnu-8796.121.2~5/RELEASE_X86_64
    Binaries:
      Node: 18.15.0
      npm: 9.5.0
      Yarn: 1.22.19
      pnpm: N/A
    Relevant packages:
      next: 13.4.4-canary.2
      eslint-config-next: 13.4.3
      react: 18.2.0
      react-dom: 18.2.0
      typescript: 5.0.4

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

SWC minifier (swcMinify: true)

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

https://github.com/vercel/next.js/tree/canary/examples/basic-export

To Reproduce

1. Create plain boilerplate via yarn create next-app
2. Run yarn next build --no-mangling
3. Inspect output in .next
4. Modify next.config.js to use swcMinify: true
5. Run yarn next build --no-mangling
6. Inspect output in .next, see e.g. class names are preserved.

Describe the Bug

Currently disabling terser mangling (__NEXT_MANGLING_DEBUG resp. --no-mangling) do not work with swcMinify: true (i.e. default).

Expected Behavior

__NEXT_MANGLING_DEBUG resp. --no-mangling should work regardless of swcMinify.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

[SukkaW]

@dbo Sorry for the long delay, and I finally figure the cause of the issue. I have opened the #53330 to fix this.

[github-actions]

This closed issue has been automatically locked because it had no new activity for 2 weeks. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.