std::hash<std::variant> (3) - Linux Man Pages
Defined in header <variant>
template <class... Types> (since C++17)
The template specialization of std::hash for the std::variant template allows users to obtain hashes of variant objects.
The specialization std::hash<std::variant<Types...>> is enabled (see std::hash) if every specialization in std::hash<std::remove_const_t<Types>>... is enabled, and is disabled otherwise.
The member functions of this specialization are not guaranteed to be noexcept.
Types - the types of the alternatives supported by the variant object
Unlike std::hash<std::optional>, hash of a variant does not typically equal the hash of the contained value; this makes it possible to distinguish std::variant<int, int> holding the same value as different alternatives.
This section is incomplete
Reason: no example
hash hash function object