title: Does unordered_map copy/release contained objects if there is insert/remove/rehash operation?
body: <p>I wanna store small objects in unordered_map, just wondering if it may copy/release contained objects if there is any insert/remove/rehash operation? I think unordered_map uses link list to store key/value pair, it should not need to copy/release objects like vector for memory reallocation.</p>