[libcxx-commits] [libcxx] [libc++] Implement `std::flat_multiset` (PR #128363)

[Louis Dionne via libcxx-commits]

================

----------------
ldionne wrote:

Would it make sense to try sharing a bit of code with `flat_set` here? And maybe with the other flat containers if you copy-pasted this 4 times?

https://github.com/llvm/llvm-project/pull/128363