[Bug libstdc++/122738] Accepts-invalid "struct _Atomic(int)" because _Atomic is not defined as an alias template

[janschultke at googlemail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122738

--- Comment #4 from Jan Schultke <janschultke at googlemail dot com> ---
The removal of the alias template is proposed in
https://cplusplus.github.io/LWG/issue4599