[Bug c++/89741] [9 Regression] static_assert fires when template not instantiated

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89741

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
This might actually be invalid testcase with no diagnostics required though.
Certainly no instantiations of X can be accepted.