https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98617
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Please provide the actual code, not only a CE link:
template <typename T, typename V> struct Base {};
template <typename T, typename V> using A = Base<T, V>;
template <typename T> using B = Base<T, int>;
template <typename T, typename V, typename> using C = Base<T, V>;
template<typename...T>
using AliasA = A<T...>; // this should fail
template<typename...T>
using AliasB = B<T...>;
template<typename...T>
using AliasC = C<T...>;
Reduced to remove the bits that do fail as expected:
template <typename T, typename V> struct Base {};
template <typename T, typename V> using A = Base<T, V>;
template<typename...T>
using AliasA = A<T...>; // this should fail
