Unordered map sure hasn't been. There are algorithmic performance guarantees in the standard that force the linked list of buckets implementation despite that b

Unordered map sure hasn't been. There are algorithmic performance guarantees in the standard that force the linked list of buckets implementation despite that being slower than alternatives. Maybe the libc++ map<> is a very perfect rbtree, but I doubt that's the state of the art in ordered containers either.