Does std::unordered_map equality depend on insertion order

Question

If you create two std::unordered_map containers using the same set of (non equal) key-value pairs, but inserted in a different order (so the containers hold equal elements, but potentially in different orders), are the containers guaranteed to be equal, according to the equality operator (operator==). I'm assuming that the hash-code and equality operators of the container elements satisfy all the required constraints on their implementation.

Answer 1

Yes, they're guaranteed to return equal in this case. The specific wording (from N4659, §[unord.req]/12) is:

Two unordered containers a and b compare equal if a.size() == b.size() and, for every equivalent-key group [Ea1, Ea2) obtained from a.equal_range(Ea1), there exists an equivalent-key group [Eb1, Eb2) obtained from b.equal_range(Ea1), such that is_permutation(Ea1, Ea2, Eb1, Eb2) returns true.

So, as long as the keys (and associated values) in one are the same as the other (but possibly in a differently-permuted order), it will compare equal.