[Compiler Bug]: Should support hooks named with symbols: use$, use_

What kind of issue is this?

• React Compiler core (the JS output is incorrect, or your app works incorrectly after optimization)
• babel-plugin-react-compiler (build issue installing or using the Babel plugin)
• eslint-plugin-react-compiler (build issue installing or using the eslint plugin)
• react-compiler-healthcheck (build issue installing or using the healthcheck script)

Link to repro

https://github.com/vladmiller/legend-state-react-compiler-bug

Repro steps

isHookName checks for valid hook names and requires alphanumeric names. I believe it should also support $ and _ since those are valid characters in JavaScript function names.

In Legend State we have a hook named use$ to consume observables, which I had thought would be compatible with Compiler. So this is currently breaking Legend State with the Compiler enabled. See issue: https://github.com/LegendApp/legend-state/issues/477

I think the isHookName regexp should be changed to this to match valid function names in JavaScript.

/^use[A-Z0-9_$]*$/

Thanks 🙏

How often does this bug happen?

Every time

What version of React are you using?

19.0.0

What version of React Compiler are you using?

19.0.0-beta-e1e972c-20250221

Start in compiler/packages/babel-plugin-react-compiler/src/HIR/Environment.ts at isHookName, then reproduce the issue with the linked Legend State example. Check how hook names containing $ and _ are classified and verify that the compiler handles use$ and use_ correctly without breaking existing hook-name behavior.