std::owner_hash

Defined in header `<memory>`
`struct owner_hash;`		(since C++26)

This function object provides owner-based (as opposed to value-based) hashing of both std::weak_ptr and std::shared_ptr.

Nested type	Definition
`is_transparent`	unspecified

operator()

calculates the hash of the shared-ownership pointer
(function)

std::owner_less::operator()

`template< class T > std::size_t operator()( const std::shared_ptr<T>& key ) const noexcept;`	(1)	(since C++26)
`template< class T > std::size_t operator()( const std::weak_ptr<T>& key ) const noexcept;`	(2)	(since C++26)

Equivalent to return key.owner_hash();.

key

shared-ownership pointer to be hashed

A hash value that is identical for any std::shared_ptr or std::weak_ptr object sharing the same ownership.

Feature-test macro	Value	Std	Feature
`__cpp_lib_smart_ptr_owner_equality`	202306L	(C++26)	Enabling the use of `std::shared_ptr` and `std::weak_ptr` as keys in unordered associative containers

owner_hash (C++26)	provides owner-based hashing of shared pointers (public member function of `std::shared_ptr<T>`)
owner_hash (C++26)	provides owner-based hashing of weak pointers (public member function of `std::weak_ptr<T>`)