20 General utilities library [utilities]
template<class... Types>
void swap(variant<Types...>& v, variant<Types...>& w) noexcept(see below);
Constraints:
is_move_constructible_v<Ti> && is_swappable_v<Ti>
is
true for all
i. Effects: Equivalent to
v.swap(w). Remarks: The expression inside
noexcept is equivalent to
noexcept(v.swap(w)).