NextJS 15.3.1 broke the React Compiler

[Daniel3711997]

Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/interesting-bird-tkf7lw

To Reproduce

Just run the app and use the React Dev Tools to see which components are memoized.

Current vs. Expected behavior

Expect that the React compiler to work

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.6.0: Thu Mar  6 22:00:07 PST 2025; root:xnu-10063.141.1.704.6~1/RELEASE_ARM64_T6030
  Available memory (MB): 18432
  Available CPU cores: 12
Binaries:
  Node: 22.15.0
  npm: 10.9.2
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 15.3.1 // Latest available version is detected (15.3.1).
  eslint-config-next: N/A
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.8.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Not sure

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

This is the pull request that caused the issue: #78260

[Daniel3711997]

Something strange is happening now, sometimes the react compiler works correctly and sometimes it just flags the component as is using 'memo' in react dev tools but looking at the compiled code there is no optimization.

This also happens when running the next build command, no code optimization is found on the compiled code but the component is flagged as 'Auto memo' in react dev tools.

Any idea what it could be?

@kdy1

[kdy1]

I have no idea. Can you file another issue with a new reproduction?

[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.