#include <array>
 
// globally:
template<typename T> 
using enum_traits = decltype(get_enum_traits(T{}));
 
// inside the macro:
#define DEFINE_ENUM(Name, ...) \
    /* define "enum class Name" ... */ \
    enum class Name { __VA_ARGS__ }; \
    struct Name##_type_traits { \
         static constexpr std::array<Name,1> values{{ Name{} }}; \
    }; \
    Name##_type_traits get_enum_traits(Name); // does not need implementation
 
 
namespace foo {
    DEFINE_ENUM(Foo, Value1, Value2);
}
 
int main( ) {
    for (auto e: enum_traits<foo::Foo>::values)
    {}
}
 

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