std::is_error_code_enum<std::future_errc>
From cppreference.com
                    
                                        
                    < cpp | thread | future errc
                    
                                                            
                    | Defined in header  <future> | ||
| template<> struct is_error_code_enum<std::future_errc> : std::true_type; | (since C++11) | |
Specifies that std::future_errc is an error code enum. This enables std::error_code automatic conversions.
[edit] See also
| (C++11) | identifies a class as an error_code enumeration (class template) | 


