[utility.syn]

/ all freestanding #include <compare> / see [compare.syn] #include <initializer_list> / see [initializer.list.syn] namespace std { / [utility.swap], swap template<class T> constexpr void swap(T& a, T& b) noexcept(see below); template<class T, size_t N> constexpr void swap(T (&a)[N], T (&b)[N]) noexcept(is_nothrow_swappable_v<T>); / [utility.exchange], exchange template<class T, class U = T> constexpr T exchange(T& obj, U&& new_val) noexcept(see below); / [forward], forward/move template<class T> constexpr T&& forward(remove_reference_t<T>& t) noexcept; template<class T> constexpr T&& forward(remove_reference_t<T>& t) noexcept; template<class T, class U> constexpr auto forward_like(U&& x) noexcept -> see below; template<class T> constexpr remove_reference_t<T>& move(T&&) noexcept; template<class T> constexpr conditional_t< !is_nothrow_move_constructible_v<T> && is_copy_constructible_v<T>, const T&, T&&> move_if_noexcept(T& x) noexcept; / [utility.as.const], as_const template<class T> constexpr add_const_t<T>& as_const(T& t) noexcept; template<class T> void as_const(const T&&) = delete; / [declval], declval template<class T> add_rvalue_reference_t<T> declval() noexcept; / as unevaluated operand / [utility.intcmp], integer comparison functions template<class T, class U> constexpr bool cmp_equal(T t, U u) noexcept; template<class T, class U> constexpr bool cmp_not_equal(T t, U u) noexcept; template<class T, class U> constexpr bool cmp_less(T t, U u) noexcept; template<class T, class U> constexpr bool cmp_greater(T t, U u) noexcept; template<class T, class U> constexpr bool cmp_less_equal(T t, U u) noexcept; template<class T, class U> constexpr bool cmp_greater_equal(T t, U u) noexcept; template<class R, class T> constexpr bool in_range(T t) noexcept; / [utility.underlying], to_underlying template<class T> constexpr underlying_type_t<T> to_underlying(T value) noexcept; / [utility.undefined], undefined behavior [[noreturn]] void unreachable(); void observable_checkpoint() noexcept; / [intseq], compile-time integer sequences template<class T, T..> struct integer_sequence; template<size_t.. I> using index_sequence = integer_sequence<size_t, I..>; template<class T, T N> using make_integer_sequence = integer_sequence<T, see below>; template<size_t N> using make_index_sequence = make_integer_sequence<size_t, N>; template<class. T> using index_sequence_for = make_index_sequence<sizeof.(T)>; / [intseq.binding], structured binding support template<class T> struct tuple_size; template<size_t I, class T> struct tuple_element; template<class T, T.. Values> struct tuple_size<integer_sequence<T, Values..>; template<size_t I, class T, T.. Values> struct tuple_element<I, integer_sequence<T, Values..>; template<size_t I, class T, T.. Values> struct tuple_element<I, const integer_sequence<T, Values..>; template<size_t I, class T, T.. Values> constexpr T get(integer_sequence<T, Values..>) noexcept; / [pairs], class template pair template<class T1, class T2> struct pair; template<class T1, class T2, class U1, class U2, template<class> class TQual, template<class> class UQual> requires requires { typename pair<common_reference_t<TQual<T1>, UQual<U1>>, common_reference_t<TQual<T2>, UQual<U2>>; } struct basic_common_reference<pair<T1, T2>, pair<U1, U2>, TQual, UQual> { using type = pair<common_reference_t<TQual<T1>, UQual<U1>>, common_reference_t<TQual<T2>, UQual<U2>>; }; template<class T1, class T2, class U1, class U2> requires requires { typename pair<common_type_t<T1, U1>, common_type_t<T2, U2>>; } struct common_type<pair<T1, T2>, pair<U1, U2>> { using type = pair<common_type_t<T1, U1>, common_type_t<T2, U2>>; }; / [pairs.spec], pair specialized algorithms template<class T1, class T2, class U1, class U2> constexpr bool operator=(const pair<T1, T2>&, const pair<U1, U2>&); template<class T1, class T2, class U1, class U2> constexpr common_comparison_category_t<synth-three-way-result<T1, U1>, synth-three-way-result<T2, U2>> operator<=>(const pair<T1, T2>&, const pair<U1, U2>&); template<class T1, class T2> constexpr void swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)); template<class T1, class T2> constexpr void swap(const pair<T1, T2>& x, const pair<T1, T2>& y) noexcept(noexcept(x.swap(y)); template<class T1, class T2> constexpr see below make_pair(T1&&, T2&&); / [pair.astuple], tuple-like access to pair template<class T1, class T2> struct tuple_size<pair<T1, T2>>; template<size_t I, class T1, class T2> struct tuple_element<I, pair<T1, T2>>; template<size_t I, class T1, class T2> constexpr tuple_element_t<I, pair<T1, T2>>& get(pair<T1, T2>&) noexcept; template<size_t I, class T1, class T2> constexpr tuple_element_t<I, pair<T1, T2>>& get(pair<T1, T2>&) noexcept; template<size_t I, class T1, class T2> constexpr const tuple_element_t<I, pair<T1, T2>>& get(const pair<T1, T2>&) noexcept; template<size_t I, class T1, class T2> constexpr const tuple_element_t<I, pair<T1, T2>>& get(const pair<T1, T2>&) noexcept; template<class T1, class T2> constexpr T1& get(pair<T1, T2>& p) noexcept; template<class T1, class T2> constexpr const T1& get(const pair<T1, T2>& p) noexcept; template<class T1, class T2> constexpr T1&& get(pair<T1, T2>& p) noexcept; template<class T1, class T2> constexpr const T1&& get(const pair<T1, T2>& p) noexcept; template<class T2, class T1> constexpr T2& get(pair<T1, T2>& p) noexcept; template<class T2, class T1> constexpr const T2& get(const pair<T1, T2>& p) noexcept; template<class T2, class T1> constexpr T2&& get(pair<T1, T2>& p) noexcept; template<class T2, class T1> constexpr const T2&& get(const pair<T1, T2>& p) noexcept; / [pair.piecewise], pair piecewise construction struct piecewise_construct_t { explicit piecewise_construct_t() = default; }; inline constexpr piecewise_construct_t piecewise_construct{}; template<class. Types> class tuple; / defined in <tuple> / in-place construction struct in_place_t { explicit in_place_t() = default; }; inline constexpr in_place_t in_place{}; template<class T> struct in_place_type_t { explicit in_place_type_t() = default; }; template<class T> constexpr in_place_type_t<T> in_place_type{}; template<size_t I> struct in_place_index_t { explicit in_place_index_t() = default; }; template<size_t I> constexpr in_place_index_t<I> in_place_index{}; / constant_arg argument tag template<auto V> struct constant_arg_t { explicit constant_arg_t() = default; }; template<auto V> constexpr constant_arg_t<V> constant_arg{}; / [variant.monostate], class monostate struct monostate; / [variant.monostate.relops], monostate relational operators constexpr bool operator=(monostate, monostate) noexcept; constexpr strong_ordering operator<=>(monostate, monostate) noexcept; / [variant.hash], hash support template<class T> struct hash; template<> struct hash<monostate>; }