[clang] [clang-tools-extra] [llvm] [Clang] Add __builtin_type_pack_dedup template to deduplicate types in template arguments (PR #106730)

[Matheus Izvekov via cfe-commits]

https://github.com/mizvekov commented:

Thanks for working on this problem!

I think the current approach is limited in ABI stability, we could broaden the usability here by designing this builtin so it produces a type list which is unique per set of types (order independent).

I had a chat with @lewissbaker a couple of months ago, and they need a similar facility for stdexec, except that ABI stability is important for them.

One possible approach would be to sort the types according to their titanium mangling, or something similarly stable.

Would that suit your needs as well?

https://github.com/llvm/llvm-project/pull/106730