If uses_allocator_v<container_type, Alloc> is false the constructors in this subclause shall not participate in overload resolution.
template <class Alloc> explicit stack(const Alloc& a);
template <class Alloc> stack(const container_type& cont, const Alloc& a);
template <class Alloc> stack(container_type&& cont, const Alloc& a);
template <class Alloc> stack(const stack& s, const Alloc& a);
template <class Alloc> stack(stack&& s, const Alloc& a);