std::promise::set_exception
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   void set_exception( std::exception_ptr p ); 
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(since C++11) | |
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.
Contents | 
[edit] Parameters
| p | - | exception pointer to store | 
[edit] Return value
(none)
[edit] Exceptions
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.
 
[edit] Example
| This section is incomplete Reason: no example  | 
[edit] See also
|    sets the result to indicate an exception while delivering the notification only at thread exit  (public member function)  | 
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