Previously, the compiler would incorrectly attempt to compile nested components/hooks defined inside non-React functions. This would lead to scope reference errors at runtime because the compiler would optimize the nested React function without understanding its closure over the parent function's variables. This PR adds detection when non-React functions declare components or hooks, and reports a clear error before compilation. I put this under a new compiler flag defaulting to false. I'll run a test on this internally first, but I expect we should be able to just turn it on in both compiler (so we stop miscompiling) and linter. Closes #33978
React Compiler
React Compiler is a compiler that optimizes React applications, ensuring that only the minimal parts of components and hooks will re-render when state changes. The compiler also validates that components and hooks follow the Rules of React.
More information about the design and architecture of the compiler are covered in the Design Goals.
More information about developing the compiler itself is covered in the Development Guide.