[clang] [libcxxabi] [llvm] [Clang] Mangling of pack indexing type and expression for itanium (PR #123513)

[Younan Zhang via llvm-commits]

https://github.com/zyn0217 commented:

Hmm, I'm unfamiliar with the libcxx/LLVM demangler part, but it does look like we're duplicating something. Can anyone explain why we have to do that?

https://github.com/llvm/llvm-project/pull/123513