[Bug c++/84222] [6/7/8 Regression] [[deprecated]] class complains about internal class usage

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84222

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 43651
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43651&action=edit
gcc8-pr84222.patch

Untested fix.