[Bug c++/79502] [[nodiscard]] attribute ignored for class template

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79502

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 40735
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40735&action=edit
gcc7-pr79502.patch

Untested fix.  The bug as I see is that we don't actually propagate the
attributes from template to its instantiations, except for non-dependent enum.