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_trivial;
template <class T> struct is_trivially_copyable;
template <class T> struct is_standard_layout;
template <class T> struct is_pod;
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, 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 has_virtual_destructor;
template <class T> struct has_unique_object_representations;
// [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 From, class To> struct is_convertible;
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 <size_t Len,
size_t Align = default-alignment> // see [meta.trans.other]
struct aligned_storage;
template <size_t Len, class... Types> struct aligned_union;
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> struct underlying_type;
template <class Fn, class... ArgTypes> struct invoke_result;
template <size_t Len,
size_t Align = default-alignment> // see [meta.trans.other]
using aligned_storage_t = typename aligned_storage<Len, Align>::type;
template <size_t Len, class... Types>
using aligned_union_t = typename aligned_union<Len, Types...>::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 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...>
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> inline constexpr bool is_void_v
= is_void<T>::value;
template <class T> inline constexpr bool is_null_pointer_v
= is_null_pointer<T>::value;
template <class T> inline constexpr bool is_integral_v
= is_integral<T>::value;
template <class T> inline constexpr bool is_floating_point_v
= is_floating_point<T>::value;
template <class T> inline constexpr bool is_array_v
= is_array<T>::value;
template <class T> inline constexpr bool is_pointer_v
= is_pointer<T>::value;
template <class T> inline constexpr bool is_lvalue_reference_v
= is_lvalue_reference<T>::value;
template <class T> inline constexpr bool is_rvalue_reference_v
= is_rvalue_reference<T>::value;
template <class T> inline constexpr bool is_member_object_pointer_v
= is_member_object_pointer<T>::value;
template <class T> inline constexpr bool is_member_function_pointer_v
= is_member_function_pointer<T>::value;
template <class T> inline constexpr bool is_enum_v
= is_enum<T>::value;
template <class T> inline constexpr bool is_union_v
= is_union<T>::value;
template <class T> inline constexpr bool is_class_v
= is_class<T>::value;
template <class T> inline constexpr bool is_function_v
= is_function<T>::value;
// [meta.unary.comp], composite type categories
template <class T> inline constexpr bool is_reference_v
= is_reference<T>::value;
template <class T> inline constexpr bool is_arithmetic_v
= is_arithmetic<T>::value;
template <class T> inline constexpr bool is_fundamental_v
= is_fundamental<T>::value;
template <class T> inline constexpr bool is_object_v
= is_object<T>::value;
template <class T> inline constexpr bool is_scalar_v
= is_scalar<T>::value;
template <class T> inline constexpr bool is_compound_v
= is_compound<T>::value;
template <class T> inline constexpr bool is_member_pointer_v
= is_member_pointer<T>::value;
// [meta.unary.prop], type properties
template <class T> inline constexpr bool is_const_v
= is_const<T>::value;
template <class T> inline constexpr bool is_volatile_v
= is_volatile<T>::value;
template <class T> inline constexpr bool is_trivial_v
= is_trivial<T>::value;
template <class T> inline constexpr bool is_trivially_copyable_v
= is_trivially_copyable<T>::value;
template <class T> inline constexpr bool is_standard_layout_v
= is_standard_layout<T>::value;
template <class T> inline constexpr bool is_pod_v
= is_pod<T>::value;
template <class T> inline constexpr bool is_empty_v
= is_empty<T>::value;
template <class T> inline constexpr bool is_polymorphic_v
= is_polymorphic<T>::value;
template <class T> inline constexpr bool is_abstract_v
= is_abstract<T>::value;
template <class T> inline constexpr bool is_final_v
= is_final<T>::value;
template <class T> inline constexpr bool is_aggregate_v
= is_aggregate<T>::value;
template <class T> inline constexpr bool is_signed_v
= is_signed<T>::value;
template <class T> inline constexpr bool is_unsigned_v
= is_unsigned<T>::value;
template <class T, class... Args> inline constexpr bool is_constructible_v
= is_constructible<T, Args...>::value;
template <class T> inline constexpr bool is_default_constructible_v
= is_default_constructible<T>::value;
template <class T> inline constexpr bool is_copy_constructible_v
= is_copy_constructible<T>::value;
template <class T> inline constexpr bool is_move_constructible_v
= is_move_constructible<T>::value;
template <class T, class U> inline constexpr bool is_assignable_v
= is_assignable<T, U>::value;
template <class T> inline constexpr bool is_copy_assignable_v
= is_copy_assignable<T>::value;
template <class T> inline constexpr bool is_move_assignable_v
= is_move_assignable<T>::value;
template <class T, class U> inline constexpr bool is_swappable_with_v
= is_swappable_with<T, U>::value;
template <class T> inline constexpr bool is_swappable_v
= is_swappable<T>::value;
template <class T> inline constexpr bool is_destructible_v
= is_destructible<T>::value;
template <class T, class... Args> inline constexpr bool is_trivially_constructible_v
= is_trivially_constructible<T, Args...>::value;
template <class T> inline constexpr bool is_trivially_default_constructible_v
= is_trivially_default_constructible<T>::value;
template <class T> inline constexpr bool is_trivially_copy_constructible_v
= is_trivially_copy_constructible<T>::value;
template <class T> inline constexpr bool is_trivially_move_constructible_v
= is_trivially_move_constructible<T>::value;
template <class T, class U> inline constexpr bool is_trivially_assignable_v
= is_trivially_assignable<T, U>::value;
template <class T> inline constexpr bool is_trivially_copy_assignable_v
= is_trivially_copy_assignable<T>::value;
template <class T> inline constexpr bool is_trivially_move_assignable_v
= is_trivially_move_assignable<T>::value;
template <class T> inline constexpr bool is_trivially_destructible_v
= is_trivially_destructible<T>::value;
template <class T, class... Args> inline constexpr bool is_nothrow_constructible_v
= is_nothrow_constructible<T, Args...>::value;
template <class T> inline constexpr bool is_nothrow_default_constructible_v
= is_nothrow_default_constructible<T>::value;
template <class T> inline constexpr bool is_nothrow_copy_constructible_v
= is_nothrow_copy_constructible<T>::value;
template <class T> inline constexpr bool is_nothrow_move_constructible_v
= is_nothrow_move_constructible<T>::value;
template <class T, class U> inline constexpr bool is_nothrow_assignable_v
= is_nothrow_assignable<T, U>::value;
template <class T> inline constexpr bool is_nothrow_copy_assignable_v
= is_nothrow_copy_assignable<T>::value;
template <class T> inline constexpr bool is_nothrow_move_assignable_v
= is_nothrow_move_assignable<T>::value;
template <class T, class U> inline constexpr bool is_nothrow_swappable_with_v
= is_nothrow_swappable_with<T, U>::value;
template <class T> inline constexpr bool is_nothrow_swappable_v
= is_nothrow_swappable<T>::value;
template <class T> inline constexpr bool is_nothrow_destructible_v
= is_nothrow_destructible<T>::value;
template <class T> inline constexpr bool has_virtual_destructor_v
= has_virtual_destructor<T>::value;
template <class T> inline constexpr bool has_unique_object_representations_v
= has_unique_object_representations<T>::value;
// [meta.unary.prop.query], type property queries
template <class T> inline constexpr size_t alignment_of_v
= alignment_of<T>::value;
template <class T> inline constexpr size_t rank_v
= rank<T>::value;
template <class T, unsigned I = 0> inline constexpr size_t extent_v
= extent<T, I>::value;
// [meta.rel], type relations
template <class T, class U> inline constexpr bool is_same_v
= is_same<T, U>::value;
template <class Base, class Derived> inline constexpr bool is_base_of_v
= is_base_of<Base, Derived>::value;
template <class From, class To> inline constexpr bool is_convertible_v
= is_convertible<From, To>::value;
template <class Fn, class... ArgTypes> inline constexpr bool is_invocable_v
= is_invocable<Fn, ArgTypes...>::value;
template <class R, class Fn, class... ArgTypes> inline constexpr bool is_invocable_r_v
= is_invocable_r<R, Fn, ArgTypes...>::value;
template <class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_v
= is_nothrow_invocable<Fn, ArgTypes...>::value;
template <class R, class Fn, class... ArgTypes> inline constexpr bool is_nothrow_invocable_r_v
= is_nothrow_invocable_r<R, Fn, ArgTypes...>::value;
// [meta.logical], logical operator traits
template<class... B> inline constexpr bool conjunction_v = conjunction<B...>::value;
template<class... B> inline constexpr bool disjunction_v = disjunction<B...>::value;
template<class B> inline constexpr bool negation_v = negation<B>::value;
}The behavior of a program that adds specializations for any of the templates defined in this subclause is undefined unless otherwise specified.