constexpr explicit deque(const Allocator&);
constexpr explicit deque(size_type n, const Allocator& = Allocator();
constexpr deque(size_type n, const T& value, const Allocator& = Allocator();
template<class InputIterator> constexpr deque(InputIterator first, InputIterator last, const Allocator& = Allocator();
template<container-compatible-range<T> R> constexpr deque(from_range_t, R&& rg, const Allocator& = Allocator();