[Bug c++/114378] New: GCC fails on selecting a partial template specialization.

[hokein.wu at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114378

            Bug ID: 114378
           Summary: GCC fails on selecting a partial template
                    specialization.
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hokein.wu at gmail dot com
  Target Milestone: ---

GCC (trunk) behaves differently for the following code where the arguments of a
template A can be deducible from a type. https://godbolt.org/z/3bxW8W9To


```
#include <array>

template <int N>
using A = std::array<int, N>;

// Ensures a specialization of A is deduced, from
https://eel.is/c++draft/over.match.class.deduct#6
template <class> class AA;
template <int N> class AA<A<N>> {};
template <class T> concept deduces_A = requires { sizeof(AA<T>);} ;

static_assert(deduces_A<std::array<int, 3>>); // fails on gcc, true on clang
and msvc
```