23 Containers library [containers]

23.5 Unordered associative containers [unord]

23.5.4 Class template unordered_map [unord.map]

23.5.4.5 unordered_map swap [unord.map.swap]

template <class Key, class T, class Hash, class Pred, class Alloc> void swap(unordered_map<Key, T, Hash, Pred, Alloc>& x, unordered_map<Key, T, Hash, Pred, Alloc>& y) noexcept(noexcept(x.swap(y)));

Effects: As if by x.swap(y).