::underlying_type

#include <type_traits>

namespace details {

  template<typename Type, bool IsEnum = std::is_enum<Type>::value>
  struct underlying_type : std::underlying_type<Type> { };

  template<typename Type>
  struct underlying_type<Type, false> { };

}

template<typename Type>
struct underlying_type : details::underlying_type<Type> { };

template<typename Type>
using underlying_type_t = typename underlying_type<Type>::type;