P1048R1 `is_scoped_enum`

[StephanTLavavej]

P1048R1 is_scoped_enum

Feature-test macro:
#define __cpp_lib_is_scoped_enum 202011L

[SuperWig]

This probably needs compiler support.

Surely it's just is_enum_v<_Ty> && !is_convertible_v<_Ty, int> ?

[StephanTLavavej]

You're absolutely right, this is WG21-N4885 [conv.integral]/1 "A prvalue of an unscoped enumeration type can be converted to a prvalue of an integer type."

However, I think that a library-only implementation will need to be careful to perform short-circuiting here. A user might have a class type where attempting to ask is_convertible_v<_Ty, int> would result in an unrecoverable hard error. conjunction should be sufficient.