From cppreference.com
This header is part of the
library.
Includes
(C++20)
support
Classes
(C++11)
wrapper around a
object, that can be used as index in associative and unordered associative containers
(class)
(C++11)
hash support for
(class template specialization)
Forward declarations Defined in header
(C++11)
hash function object
(class template)
Synopsis
#include<compare>namespacestd{classtype_index;template<classT>structhash;template<>structhash<type_index>;}Class
namespacestd{classtype_index{public:type_index(consttype_info&rhs)noexcept;booloperator==(consttype_index&rhs)constnoexcept;booloperator<(consttype_index&rhs)constnoexcept;booloperator>(consttype_index&rhs)constnoexcept;booloperator<=(consttype_index&rhs)constnoexcept;booloperator>=(consttype_index&rhs)constnoexcept;strong_orderingoperator<=>(consttype_index&rhs)constnoexcept;size_thash_code()constnoexcept;constchar*name()constnoexcept;private:consttype_info*target;// exposition only// Note that the use of a pointer here, rather than a reference,// means that the default copy/move constructor and assignment// operators will be provided and work as expected.};}