std::future_errc
From cppreference.com
                    
                                        
                    
                    
                                                            
                    |   Defined in header <ios>
   | 
||
|   enum class future_errc;  | 
(since C++11) | |
The scoped enumeration std::future_errc defines the error codes reported by std::future and related classes in std::future_error exception objects. Only four error codes are required, although the implementation may define additional error codes. Because the appropriate specialization of std::is_error_code_enum is provided, values of type std::future_errc are implicitly convertible to std::error_code.
Contents | 
[edit] Member constants
| Enumeration constant | Meaning | 
| broken_promise | the asynchronous task abandoned its shared state | 
| future_already_retrieved | the contents of shared state were already accessed through std::future | 
| promise_already_satisfied | attempt to store a value in the shared state twice | 
| no_state | attempt to access std::promise or std::future without an associated shared state | 
[edit] Helper classes
|    extends the type trait std::is_error_code_enum to identify future error codes  (class template)  | |
[edit] Non-member functions
|    constructs a future error code  (function)  | |
|    constructs a future error_condition  (function)  | |
[edit] Example
| This section is incomplete Reason: no example  | 
[edit] See also
|    (C++11)  | 
   holds a platform-dependent error code   (class)  | 
|    (C++11)  | 
   holds a portable error code  (class)  |