[Bug c++/115775] User-defined deduction guide ignored for alias template if the alias passes on a template template parameter to the aliased class template

[s.murthy at outlook dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115775

--- Comment #4 from Sean Murthy <s.murthy at outlook dot com> ---
(In reply to Xi Ruoyao from comment #2)
> Clang says:
> 
> <source>:35:10: error: deduction guide template contains a template
> parameter that cannot be deduced
... 
> but I'm not sure if this is correct (or more correct than GCC).

The little that I know about clang, it is somewhat behind on alias templates in
this area. To me, it is unclear if that error is genuinely pointing to
non-conforming code, but if that error is correctly rejecting invalid code,
then it points to an "accepts-invalid" bug in GCC.