namespace std { template <class T> struct default_delete<T[]> { constexpr default_delete() noexcept = default; template <class U> default_delete(const default_delete<U[]>&) noexcept; template <class U> void operator()(U* ptr) const; }; }
template <class U> default_delete(const default_delete<U[]>& other) noexcept;
template <class U> void operator()(U* ptr) const;