constexpr add_lvalue_reference_t<T> operator*() const noexcept(noexcept(*declval<pointer>()));
constexpr pointer operator->() const noexcept;
constexpr pointer get() const noexcept;
constexpr deleter_type& get_deleter() noexcept;
constexpr const deleter_type& get_deleter() const noexcept;
constexpr explicit operator bool() const noexcept;