[clang] [clang][constexpr] Allow IndirectGotoStmt in constexpr functions for C++23 (PR #213449)

[via cfe-commits]

babadany2999 wrote:

Hi @zwuis, I've made the following changes:
- Used a name in the release notes according to GCC documentation (https://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html).
- Moved the testing unit into its own dedicated file with a proper name (`clang/test/SemaCXX/gnu-constexpr-computed-goto.cpp`)

Please review this whenever you have time, and let me know if you see any other issues, and thank you so much for the review, I've learned a lot!

https://github.com/llvm/llvm-project/pull/213449