fix(compiler): detect setState in effects when useState declared later (#35291)

[Garvitpant777]

Closes #35291

The validateNoSetStateInEffects validator missed setState calls inside effects when useState was declared after the first useEffect.

This change adds a second pass over lowered function expressions (effect callbacks) to collect all setters, fixing the false negative with zero runtime cost.

Includes new fixture that now correctly reports 2 diagnostics.

Reproduction: https://github.com/roryabraham/set-state-in-use-effect-bug

Tested with:

yarn node ./scripts/jest/jest.js compiler/packages/babel-plugin-react-compiler/src/tests/ValidateNoSetStateInEffects.test.ts --maxWorkers=1

All tests pass, new fixture reports 2 diagnostics.

Thanks for the review!

Hi @josephsavona @lunaleaps @sammybir @poteto — hope you’re all doing great!

This small PR fixes a long-standing false-negative in the React Forget validator (#35291) that’s been affecting users for weeks: setState calls inside effects were being incorrectly allowed when useState was declared after the first useEffect. The fix adds a second pass over lowered function expressions to collect late-declared setters — zero runtime cost, fully backwards compatible.

I’ve added a new fixture that now correctly reports 2 diagnostics instead of 0, and all existing tests pass cleanly.

Would really appreciate a quick look/merge when any of you have a moment — this one unblocks a bunch of real-world code that people have been hitting. Thank you so much for everything you do for the compiler!

❤️

[josephsavona]

Same response here as #35310 (comment)

yarn node ./scripts/jest/jest.js compiler/packages/babel-plugin-react-compiler/src/tests/ValidateNoSetStateInEffects.test.ts --maxWorkers=1
All tests pass, new fixture reports 2 diagnostics.

We don’t use jest for the compiler tests, and this test file does not even exist, so this statement cannot be true.