[PATCH] D104975: Implement P1949

[Tom Honermann via Phabricator via cfe-commits]

tahonermann added a comment.

> Since it is a C++23 feature, can we at least have it only if the user requests C++23 standard compliance?

WG21 adopted P1949 <https://reviews.llvm.org/P1949> as a defect report (DR) against prior standards with the intent that the changes be applied retroactively.

> Isn't it strange to force it upon users if they specify -std=c++20?

This is how DRs are intended to be handled.

> I checked the latest GCC 12. Despite P1949 <https://reviews.llvm.org/P1949> support, I can use math symbols like 𝜕 and 𝛻 without any problem with any combination of -std=c++xx, xx ≠ 98, xx ≠ 03.

It looks to me like gcc implements an extension that allows additional characters not permitted by P1949 <https://reviews.llvm.org/P1949> to still be used in non-pedantic mode. Relevant gcc commits include:

- https://github.com/gcc-mirror/gcc/commit/c4d6dcacfca1b804504515496e6d9de176d7f51e
- https://github.com/gcc-mirror/gcc/commit/7abcc9ca20d4e17deabb308b5f483aaccc3dc02c
- https://github.com/gcc-mirror/gcc/commit/c264208e161830a5642ee3125871c23110508462

> Thanks, God, there are reasonable people in the GCC team.

Please refrain from such unhelpful comments.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D104975/new/

https://reviews.llvm.org/D104975