[clang-tools-extra] [lld] [clang] [flang] [compiler-rt] [llvm] [libc] [lldb] [libcxx] [Clang][C++23] Implement P2448R2: Relaxing some constexpr restrictions (PR #77753)

[Mariya Podchishchaeva via cfe-commits]

Fznamznon wrote:

Given the problem in https://github.com/llvm/llvm-project/pull/77753#issuecomment-1912258038 , @cor3ntin , @AaronBallman WDYT about adding new flags to `CXXRecordDecl`, saying that constructor/destructor is not really `constexpr` before C++23?

https://github.com/llvm/llvm-project/pull/77753