#include <utility>

namespace std::experimental {
inline namespace fundamentals_v3 {

  // 3.1.2, Class erased_type
  struct erased_type { };

} // namespace fundamentals_v3
} // namespace std::experimental

namespace std {
  namespace experimental {
  inline namespace fundamentals_v3 {
    // 3.2.2.1, Class template propagate_const overview
    template <class T> class propagate_const;

    // 3.2.2.8, propagate_const relational operators
    template <class T>
      constexpr bool operator==(const propagate_const<T>& pt, nullptr_t);
    template <class T>
      constexpr bool operator==(nullptr_t, const propagate_const<T>& pu);

    template <class T>
      constexpr bool operator!=(const propagate_const<T>& pt, nullptr_t);
    template <class T>
      constexpr bool operator!=(nullptr_t, const propagate_const<T>& pu);

    template <class T, class U>
      constexpr bool operator==(const propagate_const<T>& pt, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator!=(const propagate_const<T>& pt, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator<(const propagate_const<T>& pt, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator>(const propagate_const<T>& pt, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator<=(const propagate_const<T>& pt, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator>=(const propagate_const<T>& pt, const propagate_const<U>& pu);

    template <class T, class U>
      constexpr bool operator==(const propagate_const<T>& pt, const U& u);
    template <class T, class U>
      constexpr bool operator!=(const propagate_const<T>& pt, const U& u);
    template <class T, class U>
      constexpr bool operator<(const propagate_const<T>& pt, const U& u);
    template <class T, class U>
      constexpr bool operator>(const propagate_const<T>& pt, const U& u);
    template <class T, class U>
      constexpr bool operator<=(const propagate_const<T>& pt, const U& u);
    template <class T, class U>
      constexpr bool operator>=(const propagate_const<T>& pt, const U& u);

    template <class T, class U>
      constexpr bool operator==(const T& t, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator!=(const T& t, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator<(const T& t, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator>(const T& t, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator<=(const T& t, const propagate_const<U>& pu);
    template <class T, class U>
      constexpr bool operator>=(const T& t, const propagate_const<U>& pu);

    // 3.2.2.9, propagate_const specialized algorithms
    template <class T>
      constexpr void swap(propagate_const<T>& pt, propagate_const<T>& pt2) noexcept(see below);

    // 3.2.2.10, propagate_const underlying pointer access
    template <class T>
      constexpr const T& get_underlying(const propagate_const<T>& pt) noexcept;
    template <class T>
      constexpr T& get_underlying(propagate_const<T>& pt) noexcept;

  } // inline namespace fundamentals_v3
  } // namespace experimental

  // 3.2.2.11, propagate_const hash support
  template <class T> struct hash;
  template <class T>
    struct hash<experimental::fundamentals_v3::propagate_const<T>>;

  // 3.2.2.12, propagate_const comparison function objects
  template <class T> struct equal_to;
  template <class T>
    struct equal_to<experimental::fundamentals_v3::propagate_const<T>>;
  template <class T> struct not_equal_to;
  template <class T>
    struct not_equal_to<experimental::fundamentals_v3::propagate_const<T>>;
  template <class T> struct less;
  template <class T>
    struct less<experimental::fundamentals_v3::propagate_const<T>>;
  template <class T> struct greater;
  template <class T>
    struct greater<experimental::fundamentals_v3::propagate_const<T>>;
  template <class T> struct less_equal;
  template <class T>
    struct less_equal<experimental::fundamentals_v3::propagate_const<T>>;
  template <class T> struct greater_equal;
  template <class T>
    struct greater_equal<experimental::fundamentals_v3::propagate_const<T>>;

} // namespace std

#include <type_traits>

namespace std::experimental {
inline namespace fundamentals_v3 {

  // See C++17 §23.15.4.1, 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;

  // See C++17 §23.15.4.2, 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;

  // See C++17 §23.15.4.3, 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_trivial_v
    = is_trivial<T>::value;
  template <class T> constexpr bool is_trivially_copyable_v
    = is_trivially_copyable<T>::value;
  template <class T> constexpr bool is_standard_layout_v
    = is_standard_layout<T>::value;
  template <class T> constexpr bool is_pod_v
    = is_pod<T>::value;
  template <class T> constexpr bool is_literal_type_v
    = is_literal_type<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_signed_v
    = is_signed<T>::value;
  template <class T> constexpr bool is_unsigned_v
    = is_unsigned<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> 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> constexpr bool is_nothrow_destructible_v
    = is_nothrow_destructible<T>::value;
  template <class T> constexpr bool has_virtual_destructor_v
    = has_virtual_destructor<T>::value;

  // See C++17 §23.15.5, 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;

  // See C++17 §23.15.6, 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 From, class To> constexpr bool is_convertible_v
    = is_convertible<From, To>::value;

  // 3.3.2, Other type transformations
  template <class> class invocation_type; // not defined
  template <class F, class... ArgTypes> class invocation_type<F(ArgTypes...)>;
  template <class> class raw_invocation_type; // not defined
  template <class F, class... ArgTypes> class raw_invocation_type<F(ArgTypes...)>;

  template <class T>
    using invocation_type_t = typename invocation_type<T>::type;
  template <class T>
    using raw_invocation_type_t = typename raw_invocation_type<T>::type;

  // 3.3.3, Detection idiom
  template <class...> using void_t = void;

  struct nonesuch {
    nonesuch() = delete;
    ~nonesuch() = delete;
    nonesuch(nonesuch const&) = delete;

    void operator=(nonesuch const&) = delete;
  };

  template <template<class...> class Op, class... Args>
    using is_detected = see below;
  template <template<class...> class Op, class... Args>
    constexpr bool is_detected_v = is_detected<Op, Args...>::value;
  template <template<class...> class Op, class... Args>
    using detected_t = see below;
  template <class Default, template<class...> class Op, class... Args>
    using detected_or = see below;
  template <class Default, template<class...> class Op, class... Args>
    using detected_or_t = typename detected_or<Default, Op, Args...>::type;
  template <class Expected, template<class...> class Op, class... Args>
    using is_detected_exact = is_same<Expected, detected_t<Op, Args...>>;
  template <class Expected, template<class...> class Op, class... Args>
    constexpr bool is_detected_exact_v
      = is_detected_exact<Expected, Op, Args...>::value;
  template <class To, template<class...> class Op, class... Args>
    using is_detected_convertible = is_convertible<detected_t<Op, Args...>, To>;
  template <class To, template<class...> class Op, class... Args>
    constexpr bool is_detected_convertible_v
      = is_detected_convertible<To, Op, Args...>::value;

} // inline namespace fundamentals_v3
} // namespace std::experimental

This sub-clause contains templates that may be used to transform one type to another following some predefined rule.

Each of the templates in this subclause shall be a TransformationTrait (C++17 §23.15.1).

Within this section, define the invocation parameters of INVOKE(f, t1, t2, ..., tN) as follows, in which T1 is the possibly cv-qualified type of t1 and U1 denotes T1& if t1 is an lvalue or T1&& if t1 is an rvalue:

• When f is a pointer to a member function of a class T the invocation parameters are U1 followed by the parameters of f matched by t2, ..., tN.
• When N == 1 and f is a pointer to member data of a class T the invocation parameter is U1.
• If f is a class object, the invocation parameters are the parameters matching t1, ..., tN of the best viable function (C++17 §16.3.3) for the arguments t1, ..., tN among the function call operators and surrogate call functions of f.
• In all other cases, the invocation parameters are the parameters of f matching t1, ... tN.

In all of the above cases, if an argument tI matches the ellipsis in the function's parameter-declaration-clause, the corresponding invocation parameter is defined to be the result of applying the default argument promotions (C++17 §8.2.2) to tI.

struct S {
  int f(double const &) const;
  void operator()(int, int);
  void operator()(char const *, int i = 2, int j = 3);
  void operator()(...);
};

Access checking is performed as if in a context unrelated to Fn and ArgTypes. Only the validity of the immediate context of the expression is considered. [ Note: The compilation of the expression can result in side effects such as the instantiation of class template specializations and function template specializations, the generation of implicitly-defined functions, and so on. Such side effects are not in the "immediate context" and can result in the program being ill-formed. — end note ]

The member raw_invocation_type<Fn(ArgTypes...)>::type shall be defined as follows. If the expression INVOKE(declval<Fn>(), declval<ArgTypes>()...) is ill-formed when treated as an unevaluated operand (C++17 §8), there shall be no member type. Otherwise:

• Let R denote result_of_t<Fn(ArgTypes...)>.
• Let the types Ti be the invocation parameters of INVOKE(declval<Fn>(), declval<ArgTypes>()...).
• Then the member type shall name the function type R(T1, T2, ...).

The member invocation_type<Fn(ArgTypes...)>::type shall be defined as follows. If raw_invocation_type<Fn(ArgTypes...)>::type does not exist, there shall be no member type. Otherwise:

• Let A1, A2, … denote ArgTypes...
• Let R(T1, T2, …) denote raw_invocation_type_t<Fn(ArgTypes...)>
• Then the member type shall name the function type R(U1, U2, …) where Ui is decay_t<Ai> if declval<Ai>() is an rvalue otherwise Ti.

template <class Default, class AlwaysVoid,
          template<class...> class Op, class... Args>
struct DETECTOR { // exposition only
  using value_t = false_type;
  using type = Default;
};

template <class Default, template<class...> class Op, class... Args>
struct DETECTOR<Default, void_t<Op<Args...>>, Op, Args...> { // exposition only
  using value_t = true_type;
  using type = Op<Args...>;
};

template <template<class...> class Op, class... Args>
  using is_detected = typename DETECTOR<nonesuch, void, Op, Args...>::value_t;

template <template<class...> class Op, class... Args>
  using detected_t = typename DETECTOR<nonesuch, void, Op, Args...>::type;

template <class Default, template<class...> class Op, class... Args>
  using detected_or = DETECTOR<Default, void, Op, Args...>;

// archetypal helper alias for a copy assignment operation:
template <class T>
  using copy_assign_t = decltype(declval<T&>() = declval<T const &>());

// plausible implementation for the is_assignable type trait:
template <class T>
  using is_copy_assignable = is_detected<copy_assign_t, T>;

// plausible implementation for an augmented is_assignable type trait
// that also checks the return type:
template <class T>
  using is_canonical_copy_assignable = is_detected_exact<T&, copy_assign_t, T>;

// archetypal helper alias for a particular type member:
template <class T>
  using diff_t = typename T::difference_type;

// alias the type member, if it exists, otherwise alias ptrdiff_t:
template <class Ptr>
  using difference_type = detected_or_t<ptrdiff_t, diff_t, Ptr>;

When a function constructor that takes a first argument of type allocator_arg_t is invoked, the second argument is treated as a type-erased allocator (5.3). If the constructor moves or makes a copy of a function object (C++17 §23.14), including an instance of the experimental::function class template, then that move or copy is performed by using-allocator construction with allocator get_memory_resource().

In the following descriptions, let ALLOCATOR_OF(f) be the allocator specified in the construction of function f, or the value of experimental::pmr::get_default_resource() at the time of the construction of f if no allocator was specified.

function& operator=(const function& f);

function& operator=(function&& f);

function& operator=(nullptr_t) noexcept;

template<class F> function& operator=(F&& f);

template<class F> function& operator=(reference_wrapper<F> f);

namespace std::experimental {
inline namespace fundamentals_v3 {

  template <class W> class observer_ptr {
    using pointer = add_pointer_t<W>;            // exposition-only
    using reference = add_lvalue_reference_t<W>; // exposition-only
  public:
    // publish our template parameter and variations thereof
    using element_type = W;

    // 5.2.2, observer_ptr constructors
    // default c’tor
    constexpr observer_ptr() noexcept;

    // pointer-accepting c’tors
    constexpr observer_ptr(nullptr_t) noexcept;
    constexpr explicit observer_ptr(pointer) noexcept;

    // copying c’tors (in addition to compiler-generated copy c’tor)
    template <class W2> constexpr observer_ptr(observer_ptr<W2>) noexcept;

    // 5.2.3, observer_ptr observers
    constexpr pointer get() const noexcept;
    constexpr reference operator*() const;
    constexpr pointer operator->() const noexcept;
    constexpr explicit operator bool() const noexcept;

    // 5.2.4, observer_ptr conversions
    constexpr explicit operator pointer() const noexcept;

    // 5.2.5, observer_ptr modifiers
    constexpr pointer release() noexcept;
    constexpr void reset(pointer = nullptr) noexcept;
    constexpr void swap(observer_ptr&) noexcept;
  }; // observer_ptr<>

} // inline namespace fundamentals_v3
} // namespace std::experimental

An instance of resource_adaptor<Allocator> is an adaptor that wraps a memory_resource interface around Allocator. In order that resource_adaptor<X<T>> and resource_adaptor<X<U>> are the same type for any allocator template X and types T and U, resource_adaptor<Allocator> is rendered as an alias to a class template such that Allocator is rebound to a char value type in every specialization of the class template. The requirements on this class template are defined below. The name resource_adaptor_imp is for exposition only and is not normative, but the definitions of the members of that class, whatever its name, are normative. In addition to the Allocator requirements (C++17 §20.5.3.5), the parameter to resource_adaptor shall meet the following additional requirements:

• typename allocator_traits<Allocator>::pointer shall be identical to typename allocator_traits<Allocator>::value_type*.
• typename allocator_traits<Allocator>::const_pointer shall be identical to typename allocator_traits<Allocator>::value_type const*.
• typename allocator_traits<Allocator>::void_pointer shall be identical to void*.
• typename allocator_traits<Allocator>::const_void_pointer shall be identical to void const*.

// The name resource_adaptor_imp is for exposition only.
template <class Allocator>
class resource_adaptor_imp : public memory_resource {
  // for exposition only
  Allocator m_alloc;

public:
  using allocator_type = Allocator;

  resource_adaptor_imp() = default;
  resource_adaptor_imp(const resource_adaptor_imp&) = default;
  resource_adaptor_imp(resource_adaptor_imp&&) = default;

  explicit resource_adaptor_imp(const Allocator& a2);
  explicit resource_adaptor_imp(Allocator&& a2);

  resource_adaptor_imp& operator=(const resource_adaptor_imp&) = default;

  allocator_type get_allocator() const { return m_alloc; }

protected:
  virtual void* do_allocate(size_t bytes, size_t alignment);
  virtual void do_deallocate(void* p, size_t bytes, size_t alignment);

  virtual bool do_is_equal(const memory_resource& other) const noexcept;
};

template <class Allocator>
  using resource_adaptor = typename resource_adaptor_imp<
    typename allocator_traits<Allocator>::template rebind_alloc<char>>;

For brevity, this section specifies the contents of 9 headers, each of which behaves as described by 1.3.

namespace std::experimental {
inline namespace fundamentals_v3 {

  // 6.1.2, Function template erase_if
  // 6.1.3, Function template erase

  // <experimental/string>
  template <class charT, class traits, class A, class Predicate>
    void erase_if(basic_string<charT, traits, A>& c, Predicate pred);
  template <class charT, class traits, class A, class U>
    void erase(basic_string<charT, traits, A>& c, const U& value);

  // <experimental/deque>
  template <class T, class A, class Predicate>
    void erase_if(deque<T, A>& c, Predicate pred);
  template <class T, class A, class U>
    void erase(deque<T, A>& c, const U& value);

  // <experimental/vector>
  template <class T, class A, class Predicate>
    void erase_if(vector<T, A>& c, Predicate pred);
  template <class T, class A, class U>
    void erase(vector<T, A>& c, const U& value);

  // <experimental/forward_list>
  template <class T, class A, class Predicate>
    void erase_if(forward_list<T, A>& c, Predicate pred);
  template <class T, class A, class U>
    void erase(forward_list<T, A>& c, const U& value);

  // <experimental/list>
  template <class T, class A, class Predicate>
    void erase_if(list<T, A>& c, Predicate pred);
  template <class T, class A, class U>
    void erase(list<T, A>& c, const U& value);

  // <experimental/map>
  template <class K, class T, class C, class A, class Predicate>
    void erase_if(map<K, T, C, A>& c, Predicate pred);
  template <class K, class T, class C, class A, class Predicate>
    void erase_if(multimap<K, T, C, A>& c, Predicate pred);

  // <experimental/set>
  template <class K, class C, class A, class Predicate>
    void erase_if(set<K, C, A>& c, Predicate pred);
  template <class K, class C, class A, class Predicate>
    void erase_if(multiset<K, C, A>& c, Predicate pred);

  // <experimental/unordered_map>
  template <class K, class T, class H, class P, class A, class Predicate>
    void erase_if(unordered_map<K, T, H, P, A>& c, Predicate pred);
  template <class K, class T, class H, class P, class A, class Predicate>
    void erase_if(unordered_multimap<K, T, H, P, A>& c, Predicate pred);

  // <experimental/unordered_set>
  template <class K, class H, class P, class A, class Predicate>
    void erase_if(unordered_set<K, H, P, A>& c, Predicate pred);
  template <class K, class H, class P, class A, class Predicate>
    void erase_if(unordered_multiset<K, H, P, A>& c, Predicate pred);

} // inline namespace fundamentals_v3
} // namespace std::experimental

#include <array>

namespace std::experimental {
inline namespace fundamentals_v3 {

  // 6.2.2, Array creation functions
  template <class D = void, class... Types>
    constexpr array<VT, sizeof...(Types)> make_array(Types&&... t);
  template <class T, size_t N>
    constexpr array<remove_cv_t<T>, N> to_array(T (&a)[N]);

} // inline namespace fundamentals_v3
} // namespace std::experimental

#include <random>

namespace std::experimental {
inline namespace fundamentals_v3 {

  // 10.1.2.1, Function template randint
  template <class IntType>
  IntType randint(IntType a, IntType b);
  void reseed();
  void reseed(default_random_engine::result_type value);

} // inline namespace fundamentals_v3
} // namespace std::experimental