Is Executor::post allowed to throw exceptions? Interaction with synchronization primitives

[anarthal]

From the Executor concept, I'd say it is. However, async_mutex::unlock() and async_event::set() are marked noexcept while calling post. While removing the noexcept from async_event::set() is trivial, removing it from async_mutex::unlock() is not because it is used from a destructor in the RAII pattern.