namespace std { template <class T> struct default_delete { constexpr default_delete() noexcept = default; template <class U> default_delete(const default_delete<U>&) noexcept; void operator()(T*) const; }; }
template <class U> default_delete(const default_delete<U>& other) noexcept;
Effects: Constructs a default_delete object from another default_delete<U> object.
Remarks: This constructor shall not participate in overload resolution unless U* is implicitly convertible to T*.
void operator()(T* ptr) const;
Effects: calls delete on ptr.
Remarks: If T is an incomplete type, the program is ill-formed.