[Bug c++/72751] anonymous union within an anonymous union accepted without diagnostic (i.e. add -Wnested-anon-types)

[mpolacek at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72751

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
We should also make sure that __extension__ suppresses the -Wnested-anon-types
diagnostic.