void asyncFun(std::promise<int> intPromise){
  int result;
  try {
    // calculate the result
    intPromise.set_value(result);
  } catch (MyException e) {
    intPromise.set_exception(std::copy_exception(e));
  }
}

std::promise<int> intPromise;
std::unique_future<int> intFuture = intPromise.get_future(); 
std::thread t(asyncFun, std::move(intPromise));              
// do some other stuff
int result = intFuture.get(); // may throw MyException