[Compiler Bug]: Overloads cause wrong function to be exported with gating

[danteissaias]

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-hooks (build issue installing or using the eslint plugin)
• react-compiler-healthcheck (build issue installing or using the healthcheck script)

Link to repro

https://playground.react.dev/#N4Igzg9grgTgxgUxALhASwLYAcIwC4AEwBUYCAynrggQL4EBmMEGBAOiAHScD0YVMBGD4CEHANxsAdtIQAPHPkZQpcPGghSSZckLAapACgCUyArrD7NBAD4EpUADaPJU+YsIMVag9op6DAB4AFQA+QzJHBDVcMwiAzTMLKyljAgBeUIJg02zbeycXWQVcT291a1J-SyCww2kCAkjogQB+OLIaxPME1Iys4Olc5N87YPyHZyIGgkE8WC0qympDCLTM6a1GgjhNfibejKbOTpTXbYI0BgJDAEJTgzS5hYLnc+3nmC1mmJgCVoOUV+8S6fTMD0071oxlctBAABoQLspAw0ABzFDobClAh4ACeWBoxAACo4oGi0FIAPJYCpSMB0RjMVgAcgARgBDNkIRwAWiwZIpUl5gg5al5u2waCiMB4ABM0PwWa5pIZgDM0Rz1FI0WZ1VtGpBYIgzBwAEoIMV4ADCLCw0oQMAAYpb5oInY4OWiwBx4TNGpgPORCXArmhHQA5DkYBCm9BgW1SmUAUSkXKict9M1ofqk9DAWsVqKEBFJ5MpNLpYBhCPAAAsIAB3ACSUjwjrTjjAKAYHK7CFoQA

Repro steps

1. Compile a function with TypeScript overload signatures with gating enabled:

import { useStore } from "../stores/store";

// Overload signatures
export function useSession(): Session | null;
export function useSession<T>(selector: (session: Session) => T): T | null;
// Implementation
export function useSession<T>(
  selector?: (session: Session) => T
): Session | T | null {
  return useStore((s) => {
    const session = s.session;
    if (!session) return null;
    return selector ? selector(session) : session;
  });
}

2. The presence of overload signatures causes export to be placed on the wrong function:

// Wrong - unoptimized variant is exported
export function useSession_unoptimized<T>(...) { ... }

// Wrong - dispatcher is not exported
function useSession(arg0) { ... }

Expected: useSession should be exported, not useSession_unoptimized

How often does this bug happen?

Every time

What version of React are you using?

19.2.4

What version of React Compiler are you using?

1.0.0