Hard coding behavior like for the STL that seems pretty questionable, especially given that std::map and std::unordered_map have poor performance compared to ot

Hard coding behavior like for the STL that seems pretty questionable, especially given that std::map and std::unordered_map have poor performance compared to other alternatives (e.g. absl::btree_map and absl::flat_hash_map, and likewise folly has better implementations).