[Bug c++/104760] Attribute [[deprecated]] causes diagnostic in never-instantiated template

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104760

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
And I think this is the same problem as in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33911#c18.  Not sure if we want to
change anything.