Warns when a coroutine accepts reference parameters. After a coroutine suspend point, references could be dangling and no longer valid. Instead, pass parameters as values.


std::future<int> someCoroutine(int& val) {
  co_await ...;
  // When the coroutine is resumed, 'val' might no longer be valid.
  if (val) ...

This check implements CP.53 from the C++ Core Guidelines.