21 Metaprogramming library [meta]

21.3 Metaprogramming and type traits [type.traits]

21.3.3 Header <type_traits> synopsis [meta.type.synop]

// all freestanding namespace std { // [meta.help], helper class template<class T, T v> struct integral_constant; template<bool B> using bool_constant = integral_constant<bool, B>; using true_type = bool_constant<true>; using false_type = bool_constant<false>; // [meta.unary.cat], primary type categories template<class T> struct is_void; template<class T> struct is_null_pointer; template<class T> struct is_integral; template<class T> struct is_floating_point; template<class T> struct is_array; template<class T> struct is_pointer; template<class T> struct is_lvalue_reference; template<class T> struct is_rvalue_reference; template<class T> struct is_member_object_pointer; template<class T> struct is_member_function_pointer; template<class T> struct is_enum; template<class T> struct is_union; template<class T> struct is_class; template<class T> struct is_function; // [meta.unary.comp], composite type categories template<class T> struct is_reference; template<class T> struct is_arithmetic; template<class T> struct is_fundamental; template<class T> struct is_object; template<class T> struct is_scalar; template<class T> struct is_compound; template<class T> struct is_member_pointer; // [meta.unary.prop], type properties template<class T> struct is_const; template<class T> struct is_volatile; template<class T> struct is_trivially_copyable; template<class T> struct is_trivially_relocatable; template<class T> struct is_replaceable; template<class T> struct is_standard_layout; template<class T> struct is_empty; template<class T> struct is_polymorphic; template<class T> struct is_abstract; template<class T> struct is_final; template<class T> struct is_aggregate; template<class T> struct is_signed; template<class T> struct is_unsigned; template<class T> struct is_bounded_array; template<class T> struct is_unbounded_array; template<class T> struct is_scoped_enum; template<class T, class... Args> struct is_constructible; template<class T> struct is_default_constructible; template<class T> struct is_copy_constructible; template<class T> struct is_move_constructible; template<class T, class U> struct is_assignable; template<class T> struct is_copy_assignable; template<class T> struct is_move_assignable; template<class T, class U> struct is_swappable_with; template<class T> struct is_swappable; template<class T> struct is_destructible; template<class T, class... Args> struct is_trivially_constructible; template<class T> struct is_trivially_default_constructible; template<class T> struct is_trivially_copy_constructible; template<class T> struct is_trivially_move_constructible; template<class T, class U> struct is_trivially_assignable; template<class T> struct is_trivially_copy_assignable; template<class T> struct is_trivially_move_assignable; template<class T> struct is_trivially_destructible; template<class T, class... Args> struct is_nothrow_constructible; template<class T> struct is_nothrow_default_constructible; template<class T> struct is_nothrow_copy_constructible; template<class T> struct is_nothrow_move_constructible; template<class T, class U> struct is_nothrow_assignable; template<class T> struct is_nothrow_copy_assignable; template<class T> struct is_nothrow_move_assignable; template<class T, class U> struct is_nothrow_swappable_with; template<class T> struct is_nothrow_swappable; template<class T> struct is_nothrow_destructible; template<class T> struct is_nothrow_relocatable; template<class T> struct is_implicit_lifetime; template<class T> struct has_virtual_destructor; template<class T> struct has_unique_object_representations; template<class T, class U> struct reference_constructs_from_temporary; template<class T, class U> struct reference_converts_from_temporary; // [meta.unary.prop.query], type property queries template<class T> struct alignment_of; template<class T> struct rank; template<class T, unsigned I = 0> struct extent; // [meta.rel], type relations template<class T, class U> struct is_same; template<class Base, class Derived> struct is_base_of; template<class Base, class Derived> struct is_virtual_base_of; template<class From, class To> struct is_convertible; template<class From, class To> struct is_nothrow_convertible; template<class T, class U> struct is_layout_compatible; template<class Base, class Derived> struct is_pointer_interconvertible_base_of; template<class Fn, class... ArgTypes> struct is_invocable; template<class R, class Fn, class... ArgTypes> struct is_invocable_r; template<class Fn, class... ArgTypes> struct is_nothrow_invocable; template<class R, class Fn, class... ArgTypes> struct is_nothrow_invocable_r; // [meta.trans.cv], const-volatile modifications template<class T> struct remove_const; template<class T> struct remove_volatile; template<class T> struct remove_cv; template<class T> struct add_const; template<class T> struct add_volatile; template<class T> struct add_cv; template<class T> using remove_const_t = typename remove_const<T>::type; template<class T> using remove_volatile_t = typename remove_volatile<T>::type; template<class T> using remove_cv_t = typename remove_cv<T>::type; template<class T> using add_const_t = typename add_const<T>::type; template<class T> using add_volatile_t = typename add_volatile<T>::type; template<class T> using add_cv_t = typename add_cv<T>::type; // [meta.trans.ref], reference modifications template<class T> struct remove_reference; template<class T> struct add_lvalue_reference; template<class T> struct add_rvalue_reference; template<class T> using remove_reference_t = typename remove_reference<T>::type; template<class T> using add_lvalue_reference_t = typename add_lvalue_reference<T>::type; template<class T> using add_rvalue_reference_t = typename add_rvalue_reference<T>::type; // [meta.trans.sign], sign modifications template<class T> struct make_signed; template<class T> struct make_unsigned; template<class T> using make_signed_t = typename make_signed<T>::type; template<class T> using make_unsigned_t = typename make_unsigned<T>::type; // [meta.trans.arr], array modifications template<class T> struct remove_extent; template<class T> struct remove_all_extents; template<class T> using remove_extent_t = typename remove_extent<T>::type; template<class T> using remove_all_extents_t = typename remove_all_extents<T>::type; // [meta.trans.ptr], pointer modifications template<class T> struct remove_pointer; template<class T> struct add_pointer; template<class T> using remove_pointer_t = typename remove_pointer<T>::type; template<class T> using add_pointer_t = typename add_pointer<T>::type; // [meta.trans.other], other transformations template<class T> struct type_identity; template<class T> struct remove_cvref; template<class T> struct decay; template<bool, class T = void> struct enable_if; template<bool, class T, class F> struct conditional; template<class... T> struct common_type; template<class T, class U, template<class> class TQual, template<class> class UQual> struct basic_common_reference { }; template<class... T> struct common_reference; template<class T> struct underlying_type; template<class Fn, class... ArgTypes> struct invoke_result; template<class T> struct unwrap_reference; template<class T> struct unwrap_ref_decay; template<class T> using type_identity_t = typename type_identity<T>::type; template<class T> using remove_cvref_t = typename remove_cvref<T>::type; template<class T> using decay_t = typename decay<T>::type; template<bool B, class T = void> using enable_if_t = typename enable_if<B, T>::type; template<bool B, class T, class F> using conditional_t = typename conditional<B, T, F>::type; template<class... T> using common_type_t = typename common_type<T...>::type; template<class... T> using common_reference_t = typename common_reference<T...>::type; template<class T> using underlying_type_t = typename underlying_type<T>::type; template<class Fn, class... ArgTypes> using invoke_result_t = typename invoke_result<Fn, ArgTypes...>::type; template<class T> using unwrap_reference_t = typename unwrap_reference<T>::type; template<class T> using unwrap_ref_decay_t = typename unwrap_ref_decay<T>::type; template<class...> using void_t = void; // [meta.logical], logical operator traits template<class... B> struct conjunction; template<class... B> struct disjunction; template<class B> struct negation; // [meta.unary.cat], primary type categories template<class T> constexpr bool is_void_v = is_void<T>::value; template<class T> constexpr bool is_null_pointer_v = is_null_pointer<T>::value; template<class T> constexpr bool is_integral_v = is_integral<T>::value; template<class T> constexpr bool is_floating_point_v = is_floating_point<T>::value; template<class T> constexpr bool is_array_v = is_array<T>::value; template<class T> constexpr bool is_pointer_v = is_pointer<T>::value; template<class T> constexpr bool is_lvalue_reference_v = is_lvalue_reference<T>::value; template<class T> constexpr bool is_rvalue_reference_v = is_rvalue_reference<T>::value; template<class T> constexpr bool is_member_object_pointer_v = is_member_object_pointer<T>::value; template<class T> constexpr bool is_member_function_pointer_v = is_member_function_pointer<T>::value; template<class T> constexpr bool is_enum_v = is_enum<T>::value; template<class T> constexpr bool is_union_v = is_union<T>::value; template<class T> constexpr bool is_class_v = is_class<T>::value; template<class T> constexpr bool is_function_v = is_function<T>::value; // [meta.unary.comp], composite type categories template<class T> constexpr bool is_reference_v = is_reference<T>::value; template<class T> constexpr bool is_arithmetic_v = is_arithmetic<T>::value; template<class T> constexpr bool is_fundamental_v = is_fundamental<T>::value; template<class T> constexpr bool is_object_v = is_object<T>::value; template<class T> constexpr bool is_scalar_v = is_scalar<T>::value; template<class T> constexpr bool is_compound_v = is_compound<T>::value; template<class T> constexpr bool is_member_pointer_v = is_member_pointer<T>::value; // [meta.unary.prop], type properties template<class T> constexpr bool is_const_v = is_const<T>::value; template<class T> constexpr bool is_volatile_v = is_volatile<T>::value; template<class T> constexpr bool is_trivially_copyable_v = is_trivially_copyable<T>::value; template<class T> constexpr bool is_trivially_relocatable_v = is_trivially_relocatable<T>::value; template<class T> constexpr bool is_standard_layout_v = is_standard_layout<T>::value; template<class T> constexpr bool is_empty_v = is_empty<T>::value; template<class T> constexpr bool is_polymorphic_v = is_polymorphic<T>::value; template<class T> constexpr bool is_abstract_v = is_abstract<T>::value; template<class T> constexpr bool is_final_v = is_final<T>::value; template<class T> constexpr bool is_aggregate_v = is_aggregate<T>::value; template<class T> constexpr bool is_signed_v = is_signed<T>::value; template<class T> constexpr bool is_unsigned_v = is_unsigned<T>::value; template<class T> constexpr bool is_bounded_array_v = is_bounded_array<T>::value; template<class T> constexpr bool is_unbounded_array_v = is_unbounded_array<T>::value; template<class T> constexpr bool is_scoped_enum_v = is_scoped_enum<T>::value; template<class T, class... Args> constexpr bool is_constructible_v = is_constructible<T, Args...>::value; template<class T> constexpr bool is_default_constructible_v = is_default_constructible<T>::value; template<class T> constexpr bool is_copy_constructible_v = is_copy_constructible<T>::value; template<class T> constexpr bool is_move_constructible_v = is_move_constructible<T>::value; template<class T, class U> constexpr bool is_assignable_v = is_assignable<T, U>::value; template<class T> constexpr bool is_copy_assignable_v = is_copy_assignable<T>::value; template<class T> constexpr bool is_move_assignable_v = is_move_assignable<T>::value; template<class T, class U> constexpr bool is_swappable_with_v = is_swappable_with<T, U>::value; template<class T> constexpr bool is_swappable_v = is_swappable<T>::value; template<class T> constexpr bool is_destructible_v = is_destructible<T>::value; template<class T, class... Args> constexpr bool is_trivially_constructible_v = is_trivially_constructible<T, Args...>::value; template<class T> constexpr bool is_trivially_default_constructible_v = is_trivially_default_constructible<T>::value; template<class T> constexpr bool is_trivially_copy_constructible_v = is_trivially_copy_constructible<T>::value; template<class T> constexpr bool is_trivially_move_constructible_v = is_trivially_move_constructible<T>::value; template<class T, class U> constexpr bool is_trivially_assignable_v = is_trivially_assignable<T, U>::value; template<class T> constexpr bool is_trivially_copy_assignable_v = is_trivially_copy_assignable<T>::value; template<class T> constexpr bool is_trivially_move_assignable_v = is_trivially_move_assignable<T>::value; template<class T> constexpr bool is_trivially_destructible_v = is_trivially_destructible<T>::value; template<class T, class... Args> constexpr bool is_nothrow_constructible_v = is_nothrow_constructible<T, Args...>::value; template<class T> constexpr bool is_nothrow_default_constructible_v = is_nothrow_default_constructible<T>::value; template<class T> constexpr bool is_nothrow_copy_constructible_v = is_nothrow_copy_constructible<T>::value; template<class T> constexpr bool is_nothrow_move_constructible_v = is_nothrow_move_constructible<T>::value; template<class T, class U> constexpr bool is_nothrow_assignable_v = is_nothrow_assignable<T, U>::value; template<class T> constexpr bool is_nothrow_copy_assignable_v = is_nothrow_copy_assignable<T>::value; template<class T> constexpr bool is_nothrow_move_assignable_v = is_nothrow_move_assignable<T>::value; template<class T, class U> constexpr bool is_nothrow_swappable_with_v = is_nothrow_swappable_with<T, U>::value; template<class T> constexpr bool is_nothrow_swappable_v = is_nothrow_swappable<T>::value; template<class T> constexpr bool is_nothrow_destructible_v = is_nothrow_destructible<T>::value; template<class T> constexpr bool is_nothrow_relocatable_v = is_nothrow_relocatable<T>::value; template<class T> constexpr bool is_implicit_lifetime_v = is_implicit_lifetime<T>::value; template<class T> constexpr bool is_replaceable_v = is_replaceable<T>::value; template<class T> constexpr bool has_virtual_destructor_v = has_virtual_destructor<T>::value; template<class T> constexpr bool has_unique_object_representations_v = has_unique_object_representations<T>::value; template<class T, class U> constexpr bool reference_constructs_from_temporary_v = reference_constructs_from_temporary<T, U>::value; template<class T, class U> constexpr bool reference_converts_from_temporary_v = reference_converts_from_temporary<T, U>::value; // [meta.unary.prop.query], type property queries template<class T> constexpr size_t alignment_of_v = alignment_of<T>::value; template<class T> constexpr size_t rank_v = rank<T>::value; template<class T, unsigned I = 0> constexpr size_t extent_v = extent<T, I>::value; // [meta.rel], type relations template<class T, class U> constexpr bool is_same_v = is_same<T, U>::value; template<class Base, class Derived> constexpr bool is_base_of_v = is_base_of<Base, Derived>::value; template<class Base, class Derived> constexpr bool is_virtual_base_of_v = is_virtual_base_of<Base, Derived>::value; template<class From, class To> constexpr bool is_convertible_v = is_convertible<From, To>::value; template<class From, class To> constexpr bool is_nothrow_convertible_v = is_nothrow_convertible<From, To>::value; template<class T, class U> constexpr bool is_layout_compatible_v = is_layout_compatible<T, U>::value; template<class Base, class Derived> constexpr bool is_pointer_interconvertible_base_of_v = is_pointer_interconvertible_base_of<Base, Derived>::value; template<class Fn, class... ArgTypes> constexpr bool is_invocable_v = is_invocable<Fn, ArgTypes...>::value; template<class R, class Fn, class... ArgTypes> constexpr bool is_invocable_r_v = is_invocable_r<R, Fn, ArgTypes...>::value; template<class Fn, class... ArgTypes> constexpr bool is_nothrow_invocable_v = is_nothrow_invocable<Fn, ArgTypes...>::value; template<class R, class Fn, class... ArgTypes> constexpr bool is_nothrow_invocable_r_v = is_nothrow_invocable_r<R, Fn, ArgTypes...>::value; // [meta.logical], logical operator traits template<class... B> constexpr bool conjunction_v = conjunction<B...>::value; template<class... B> constexpr bool disjunction_v = disjunction<B...>::value; template<class B> constexpr bool negation_v = negation<B>::value; // [meta.member], member relationships template<class S, class M> constexpr bool is_pointer_interconvertible_with_class(M S::*m) noexcept; template<class S1, class S2, class M1, class M2> constexpr bool is_corresponding_member(M1 S1::*m1, M2 S2::*m2) noexcept; // [meta.const.eval], constant evaluation context constexpr bool is_constant_evaluated() noexcept; consteval bool is_within_lifetime(const auto*) noexcept; }