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std:: is_error_code_enum

From cppreference.net
C++
Utilities library
Diagnostics library
std::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 (such as std::io_errc and std::future_errc ), this template provides the member constant value equal true . For any other type, value is false .

This template may be specialized for a program-defined type to indicate that the type is eligible for std::error_code implicit conversion.

Contents

Helper variable template

template < class T >
constexpr bool is_error_code_enum_v = is_error_code_enum < T > :: value ;
(since C++17)

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)
operator()
(C++14)
returns value
(public member function)

Member types

Type Definition
value_type bool
type std:: integral_constant < bool , value >
Run this code 
#include <ios>
#include <system_error>
static_assert(std::is_error_code_enum_v<decltype(std::io_errc::stream)>);
static_assert(!std::is_error_code_enum_v<std::error_category>);
int main() {}

See also

(C++11)
identifies an enumeration as an std::error_condition
(class template)