std:: is_error_code_enum

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.

Helper variable template

#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