20 Memory management library [mem]

20.3 Smart pointers [smartptr]

20.3.3 Smart pointer hash support [util.smartptr.hash]

template<class T, class D> struct hash<unique_ptr<T, D>>;
Letting UP be unique_ptr<T, D>, the specialization hash<UP> is enabled ([unord.hash]) if and only if hash<typename UP​::​pointer> is enabled.
When enabled, for an object p of type UP, hash<UP>()(p) evaluates to the same value as hash<typename UP​::​pointer>()(p.get()).
The member functions are not guaranteed to be noexcept.
template<class T> struct hash<shared_ptr<T>>;
For an object p of type shared_ptr<T>, hash<shared_ptr<T>>()(p) evaluates to the same value as hash<typename shared_ptr<T>​::​element_type*>()(p.get()).