[Bug c++/71794] Std::array as an incomplete type in nested name specifier.

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71794

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
If you fix your partial specialization it works with all compilers:

template <typename T, std::size_t N>  /* correct type */
struct B<std::array<T, N>>
{
  static std::array<T, N> bar()
  {
      return std::array<T, N>();
  }
};