Function co_spawn_entry_point

demo_example/asio/asio/impl/co_spawn.hpp:80–142

template <typename T, typename Executor, typename F, typename Handler>
awaitable<awaitable_thread_entry_point, Executor> co_spawn_entry_point(
    awaitable<T, Executor>*, Executor ex, F f, Handler handler)
{
  auto spawn_work = make_co_spawn_work_guard(ex);
  auto handler_work = make_co_spawn_work_guard(
      asio::get_associated_executor(handler, ex));

  (void) co_await (dispatch)(
      use_awaitable_t<Executor>{__FILE__, __LINE__, "co_spawn_entry_point"});

  (co_await awaitable_thread_has_context_switched{}) = false;
  std::exception_ptr e = nullptr;
  bool done = false;
  try
  {
    T t = co_await f();

    done = true;

    if (co_await awaitable_thread_has_context_switched{})
    {
      (dispatch)(handler_work.get_executor(),
          [handler = std::move(handler), t = std::move(t)]() mutable
          {
            std::move(handler)(std::exception_ptr(), std::move(t));
          });
    }
    else
    {
      (post)(handler_work.get_executor(),
          [handler = std::move(handler), t = std::move(t)]() mutable
          {
            std::move(handler)(std::exception_ptr(), std::move(t));
          });
    }

    co_return;
  }
  catch (...)
  {
    if (done)
      throw;

    e = std::current_exception();
  }

  if (co_await awaitable_thread_has_context_switched{})
  {
    (dispatch)(handler_work.get_executor(),
        [handler = std::move(handler), e]() mutable
        {
          std::move(handler)(e, T());
        });
  }
  else
  {
    (post)(handler_work.get_executor(),
        [handler = std::move(handler), e]() mutable