See this example: https://github.com/facebook/react/issues/11508#issuecomment-345464797.

I think it probably reflects a misunderstanding of how props and state work, and we should detect and warn if we see this.
startPhaseTimer(workInProgress, 'componentWillMount');
  const oldState = instance.state;
  if (typeof instance.componentWillMount === 'function') {
    instance.componentWillMount();
  }
  if (typeof instance.UNSAFE_componentWillMount === 'function') {
    instance.UNSAFE_componentWillMount();
  }
  stopPhaseTimer();
  if (oldState !== instance.state) {
    if (__DEV__) {
      warningWithoutStack(
        false,
        '%s.componentWillMount(): Assigning directly to this.state is ' +
          "deprecated (except inside a component's " +
          'constructor). Use setState instead.',
        getComponentName(workInProgress.type) || 'Component',
      );
    }
    classComponentUpdater.enqueueReplaceState(instance, instance.state, null);
  }
}
function callComponentWillReceiveProps(