[Bug c++/85140] [6/7/8 Regression] ICE with invalid use of alignas

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85140

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 43814
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43814&action=edit
gcc8-pr85140.patch

Untested fix.