WTF::isValidEnum() has a typo in static_assert making it a tautological comparison.

template<typename E, typename T, std::enable_if_t<std::is_enum<E>::value && !std::is_same<std::underlying_type_t<E>, bool>::value && !HasCustomIsValidEnum<E>::value>* = nullptr>
constexpr bool isValidEnum(T t)
{
    static_assert(sizeof(T) >= std::underlying_type_t<E>(), "Integral type must be at least the size of the underlying enum type");

    return EnumValueChecker<T, typename EnumTraits<E>::values>::isValidEnum(t);
}

Note that `sizeof(T) >= std::underlying_type_t<E>()` is a tautological comparison because `std::underlying_type_t<E>()` evaluates to zero.