[Bug c++/116005] Class template argument deduction for alias templates error in C++20

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116005

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
clang rejects it with:

<source>:11:1: error: deduction guide template contains a template parameter
that cannot be deduced
   11 | A(std::vector<T1> const &) -> A<const T1, T2>;
      | ^
<source>:10:33: note: non-deducible template parameter 'T2'
   10 | template <typename T1, typename T2>
      |                                 ^