constexpr variant() noexcept(see below);
constexpr variant(const variant& w);
constexpr variant(variant&& w) noexcept(see below);
template<class T> constexpr variant(T&& t) noexcept(see below);
template<class T, class... Args> constexpr explicit variant(in_place_type_t<T>, Args&&... args);
template<class T, class U, class... Args>
constexpr explicit variant(in_place_type_t<T>, initializer_list<U> il, Args&&... args);
template<size_t I, class... Args> constexpr explicit variant(in_place_index_t<I>, Args&&... args);
template<size_t I, class U, class... Args>
constexpr explicit variant(in_place_index_t<I>, initializer_list<U> il, Args&&... args);
constexpr ~variant();
constexpr variant& operator=(const variant& rhs);
constexpr variant& operator=(variant&& rhs) noexcept(see below);
template<class T> constexpr variant& operator=(T&& t) noexcept(see below);
template<class T, class... Args> constexpr T& emplace(Args&&... args);
template<class T, class U, class... Args>
constexpr T& emplace(initializer_list<U> il, Args&&... args);
template<size_t I, class... Args>
constexpr variant_alternative_t<I, variant<Types...>>& emplace(Args&&... args);
template<size_t I, class U, class... Args>
constexpr variant_alternative_t<I, variant<Types...>>&
emplace(initializer_list<U> il, Args&&... args);
constexpr bool valueless_by_exception() const noexcept;
constexpr size_t index() const noexcept;
constexpr void swap(variant& rhs) noexcept(see below);
template<class T> struct variant_size;
template<class T> struct variant_size<const T>;
template<class... Types>
struct variant_size<variant<Types...>> : integral_constant<size_t, sizeof...(Types)> { };
template<size_t I, class T> struct variant_alternative<I, const T>;
variant_alternative<I, variant<Types...>>::type
template<class T, class... Types>
constexpr bool holds_alternative(const variant<Types...>& v) noexcept;
template<size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>>& get(variant<Types...>& v);
template<size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>>&& get(variant<Types...>&& v);
template<size_t I, class... Types>
constexpr const variant_alternative_t<I, variant<Types...>>& get(const variant<Types...>& v);
template<size_t I, class... Types>
constexpr const variant_alternative_t<I, variant<Types...>>&& get(const variant<Types...>&& v);
template<class T, class... Types> constexpr T& get(variant<Types...>& v);
template<class T, class... Types> constexpr T&& get(variant<Types...>&& v);
template<class T, class... Types> constexpr const T& get(const variant<Types...>& v);
template<class T, class... Types> constexpr const T&& get(const variant<Types...>&& v);
template<size_t I, class... Types>
constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>>
get_if(variant<Types...>* v) noexcept;
template<size_t I, class... Types>
constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>>
get_if(const variant<Types...>* v) noexcept;
template<class T, class... Types>
constexpr add_pointer_t<T>
get_if(variant<Types...>* v) noexcept;
template<class T, class... Types>
constexpr add_pointer_t<const T>
get_if(const variant<Types...>* v) noexcept;
template<class... Types>
constexpr bool operator==(const variant<Types...>& v, const variant<Types...>& w);
template<class... Types>
constexpr bool operator!=(const variant<Types...>& v, const variant<Types...>& w);
template<class... Types>
constexpr bool operator<(const variant<Types...>& v, const variant<Types...>& w);
template<class... Types>
constexpr bool operator>(const variant<Types...>& v, const variant<Types...>& w);
template<class... Types>
constexpr bool operator<=(const variant<Types...>& v, const variant<Types...>& w);
template<class... Types>
constexpr bool operator>=(const variant<Types...>& v, const variant<Types...>& w);
template<class... Types> requires (three_way_comparable<Types> && ...)
constexpr common_comparison_category_t<compare_three_way_result_t<Types>...>
operator<=>(const variant<Types...>& v, const variant<Types...>& w);
template<class Visitor, class... Variants>
constexpr see below visit(Visitor&& vis, Variants&&... vars);
template<class R, class Visitor, class... Variants>
constexpr R visit(Visitor&& vis, Variants&&... vars);
struct monostate{};
constexpr bool operator==(monostate, monostate) noexcept { return true; }
constexpr strong_ordering operator<=>(monostate, monostate) noexcept
{ return strong_ordering::equal; }
template<class... Types>
constexpr void swap(variant<Types...>& v, variant<Types...>& w) noexcept(see below);
const char* what() const noexcept override;
template<class... Types> struct hash<variant<Types...>>;
template<> struct hash<monostate>;