[Bug c++/110338] Implement C++26 language features

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110338
Bug 110338 depends on bug 110343, which changed state.

Bug 110343 Summary: [C++26] P2558R2 - Add @, $, and ` to the basic character set
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110343

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