Foo() — react Function Reference

Source Code

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.invalid-hoisting-setstate.js lines 5–23

function Foo() {
  /**
   * Previously, this lowered to
   * $1 = LoadContext capture setState
   * $2 = FunctionExpression deps=$1 context=setState
   *  [[ at this point, we freeze the `LoadContext setState` instruction, but it will never be referenced again ]]
   *
   * Now, this function expression directly references `setState`, which freezes
   * the source `DeclareContext HoistedConst setState`. Freezing source identifiers
   * (instead of the one level removed `LoadContext`) is more semantically correct
   * for everything *other* than hoisted context declarations.
   *
   * $2 = Function context=setState
   */
  useEffect(() => setState(2), []);

  const [state, setState] = useState(0);
  return <Stringify state={state} />;
}