https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118104
--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
A little different test I've been using:
```
template<typename... Zs> struct Z { };
template <class... Ts> struct X {
template <class... Us> using Y = Z<void(Ts, Us)...>;
};
template <class A, class... P>
using foo = X<int, int>::Y<A, P...>;
```
