::is_scoped_enum, ::is_unscoped_enum

#include <type_traits>

namespace details {

  template<typename T, bool IsEnum = std::is_enum<T>::value>
  struct is_unscoped_enum {
    using underlying_type = typename std::underlying_type<T>::type;
    using type = typename std::is_convertible<T, underlying_type>::type;
  };

  template<typename T>
  struct is_unscoped_enum<T, false> {
    using type = std::false_type;
  };

  template<typename T, bool IsEnum = std::is_enum<T>::value>
  struct is_scoped_enum {
    using underlying_type = typename std::underlying_type<T>::type;
    using type = std::integral_constant<bool, !std::is_convertible<T, underlying_type>::value>;
  };

  template<typename T>
  struct is_scoped_enum<T, false> {
    using type = std::false_type;
  };

}

template<typename T>
struct is_unscoped_enum : details::is_unscoped_enum<T>::type { };

template<typename T>
struct is_scoped_enum : details::is_scoped_enum<T>::type { };

#if __cpp_variable_templates == 201304

template<typename T>
constexpr bool is_unscoped_enum_v = is_unscoped_enum<T>::value;

template<typename T>
constexpr bool is_scoped_enum_v = is_scoped_enum<T>::value;

#endif