[Bug c++/118543] Previous forward declaration of enum causes early instantiation of later definition

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118543

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
There are defect reports in this area too.

I can also get an ICE with:
```

template<class T>
struct S {
    enum class E : T;
    enum E0 : T;
    static constexpr T f(int) { return 0; };
    static constexpr T f(char) { return 1; };
};

template<class T>
    enum class S<T>::E : T { X = S<T>::f(T{}) };
template<class T>
    enum S<T>::E0 : T { X2 = S<T>::f(T{}) };
typedef S<char> S0;
static_assert((int)S0::E::X == 1);
static_assert((int)S0::X2 == 1);
```