[Bug c++/125821] Implement C++29 language features

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125821
Bug 125821 depends on bug 125830, which changed state.

Bug 125830 Summary: [C++29] P3950R1, return_value & return_void are not 
mutually exclusive
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125830

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED