std::hash (3) Linux Manual Page

std::hash<std::variant> – std::hash<std::variant>

Synopsis

Defined in header<variant>

    template <class... Types>
    (since C++ 17)

        struct hash<std::variant<Types...>>;

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.

Template parameters

Types – the types of the alternatives supported by the variant object

Notes

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.

Example

 This section is incomplete
 Reason: no example

See also

hash hash function object
        (class template)
(C++11)