[Bug c++/124229] [reflection] using type alias defined with splice expression of annotation as template arg T to extract<T> causes ICE

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124229

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
And this shows that it's not about Reflection per se:

```
template<typename T>
void foo () { }

int main()
{
  template for (constexpr auto val : { 42 })
    {
      using U = decltype(val);
      foo<U>();
    }
}
```