std::is_error_code_enum
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                    < cpp | error | error code
                    
                                                            
                    |   Defined in header  
<system_error>
  | 
||
|   template< class T > 
struct is_error_code_enum;  | 
(since C++11) | |
If T is an error code enumeration, this template provides the member constant value equal true.  For any other type, value is false.
This template may be specialized for a user-defined type to indicate that the type is eligible for std::error_code and std::error_condition automatic conversions.
The following classes of the standard library are an error code enum:
Contents | 
Inherited from std::integral_constant
Member constants
|    value 
[static] 
 | 
   true if  T is an error code enum, false otherwise  (public static member constant)  | 
Member functions
|    operator bool  | 
   converts the object to bool, returns value  (public member function)  | 
Member types
| Type | Definition | 
  value_type
 | 
  bool
 | 
  type
 | 
std::integral_constant<bool, value> |