[util.smartptr.getdeleter]

template<class D, class T>
  D* get_deleter(const shared_ptr<T>& p) noexcept;

Returns: If p owns a deleter d of type cv-unqualified D, returns addressof(d); otherwise returns nullptr.

The returned pointer remains valid as long as there exists a shared_ptr instance that owns d.

[Note 1:

It is unspecified whether the pointer remains valid longer than that.

This can happen if the implementation doesn't destroy the deleter until all weak_ptr instances that share ownership with p have been destroyed.

— end note]

20 General utilities library [utilities]