Function useSyncExternalStore

packages/react-server/src/ReactFizzHooks.js:553–565

(
  subscribe: (() => void) => () => void,
  getSnapshot: () => T,
  getServerSnapshot?: () => T,
)

}

function useSyncExternalStore<T>(
  subscribe: (() => void) => () => void,
  getSnapshot: () => T,
  getServerSnapshot?: () => T,
): T {
  if (getServerSnapshot === undefined) {
    throw new Error(
      'Missing getServerSnapshot, which is required for ' +
        'server-rendered content. Will revert to client rendering.',
    );
  }
  return getServerSnapshot();
}

function useDeferredValue<T>(value: T, initialValue?: T): T {
  resolveCurrentlyRenderingComponent();