void set_exception( std::exception_ptr p );
Stores the exception pointer
p into the shared state and makes the state ready.
The operation is atomic, i.e. it behaves as though they acquire a single mutex associated with the promise object while updating the promise object.
An exception is thrown if there is no shared state or the shared state already stores a value or exception.
|p||-||exception pointer to store|
 Return value
std::future_error on the following conditions:
- *this has no shared state. The error category is set to no_state.
- The shared state already stores a value or exception. The error category is set to promise_already_satisfied.
|This section is incomplete|
Reason: no example
 See also
| sets the result to indicate an exception while delivering the notification only at thread exit |
(public member function)