std::swap may be specialized in namespace std for program-defined types, but such specializations are not found by ADL (the namespace std is not the associated namespace for the program-defined …

Specializes the std::swap algorithm for std::basic_string. Swaps the contents of lhs and rhs. Equivalent to lhs.swap(rhs).

This function template models the semantics of the swap operation given by Swappable. That is, overloads of swap found by ADL and the fall back of std::swap are considered.

Exchanges the contents of the container with those of other. Does not cause iterators and references to associate with the other container.

Overloads the std::swap algorithm for std::any. Swaps the content of two any objects by calling lhs.swap(rhs). Parameters

Overloads the std::swap algorithm for std::function. Exchanges the state of lhs with that of rhs. Effectively calls lhs.swap(rhs).

Exchanges the contents of the string with those of other. All iterators and references may be invalidated.

Defect reports The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

Overloads the std::swap algorithm for std::variant. Effectively calls lhs.swap(rhs). This overload participates in overload resolution only if std::is_move_constructible_v<T_i> and …

Both custom specializations and overloads of the std::swap algorithm are allowed, but the overloads are generally preferred since specializations of a function template aren't allowed for template classes. …