\begin{codeblock}

#include <initializer_list> // see \ref{initializer.list.syn}

namespace std {

// constants

inline constexpr size_t @\libglobal{dynamic_extent}@ = numeric_limits<size_t>::max();

// \ref{views.span}, class template \tcode{span}

template<class ElementType, size_t Extent = dynamic_extent>

template<class ElementType, size_t Extent>

constexpr bool ranges::@\libspec{enable_view}{span}@<span<ElementType, Extent>> = true;

\indexheader{mdspan}%

\begin{codeblock}

namespace std {

// \ref{mdspan.extents}, class template \tcode{extents}

template<class IndexType, size_t... Extents>

\ref{tuple} & Tuples & \tcode{<tuple>} \\ \rowsep

\ref{optional} & Optional objects & \tcode{<optional>} \\ \rowsep

\ref{variant} & Variants & \tcode{<variant>} \\ \rowsep

\ref{function.objects} & Function objects & \tcode{<functional>} \\ \rowsep

\ref{charconv} & Primitive numeric conversions & \tcode{<charconv>} \\ \rowsep

\ref{bit} & Bit manipulation & \tcode{<bit>} \\ \rowsep

\ref{string.view} & String view classes & \tcode{<string_view>} \\ \rowsep

\ref{string.classes} & String classes & \tcode{<string>} \\ \rowsep

\ref{c.strings} & Null-terminated sequence utilities & \tcode{<cstring>}, \tcode{<cwchar>} \\ \rowsep

\ref{array} & Class template \tcode{array} & \tcode{<array>} \\ \rowsep

\ref{iterators} & Iterators library & \tcode{<iterator>} \\ \rowsep

\ref{ranges} & Ranges library & \tcode{<ranges>} \\ \rowsep

\ref{algorithms} & Algorithms library & \tcode{<algorithm>}, \tcode{<numeric>} \\ \rowsep

// \ref{out.ptr.t}, class template \tcode{out_ptr_t}

template<class Smart, class Pointer, class... Args>

// \ref{out.ptr}, function template \tcode{out_ptr}

template<class Pointer = void, class Smart, class... Args>

// \ref{inout.ptr.t}, class template \tcode{inout_ptr_t}

template<class Smart, class Pointer, class... Args>

// \ref{inout.ptr}, function template \tcode{inout_ptr}

template<class Pointer = void, class Smart, class... Args>

}

\end{codeblock}

#define @\defnlibxname{cpp_lib_freestanding_cwchar}@ 202306L // freestanding, also in \libheader{cwchar}

#define @\defnlibxname{cpp_lib_freestanding_errc}@ 202306L

// freestanding, also in \libheader{cerrno}, \libheader{system_error}

#define @\defnlibxname{cpp_lib_freestanding_feature_test_macros}@ 202306L // freestanding

#define @\defnlibxname{cpp_lib_freestanding_functional}@ 202306L // freestanding, also in \libheader{functional}

#define @\defnlibxname{cpp_lib_freestanding_iterator}@ 202306L // freestanding, also in \libheader{iterator}

#define @\defnlibxname{cpp_lib_freestanding_memory}@ 202306L // freestanding, also in \libheader{memory}

#define @\defnlibxname{cpp_lib_freestanding_operator_new}@ @\seebelow@ // freestanding, also in \libheader{new}

#define @\defnlibxname{cpp_lib_freestanding_optional}@ 202311L // freestanding, also in \libheader{optional}

#define @\defnlibxname{cpp_lib_not_fn}@ 202306L // freestanding, also in \libheader{functional}

#define @\defnlibxname{cpp_lib_null_iterators}@ 201304L // freestanding, also in \libheader{iterator}

#define @\defnlibxname{cpp_lib_optional}@ 202110L // also in \libheader{optional}

#define @\defnlibxname{cpp_lib_parallel_algorithm}@ 201603L // also in \libheader{algorithm}, \libheader{numeric}

#define @\defnlibxname{cpp_lib_polymorphic_allocator}@ 201902L // also in \libheader{memory_resource}

#define @\defnlibxname{cpp_lib_print}@ 202207L // also in \libheader{print}, \libheader{ostream}

#define @\defnlibxname{cpp_lib_smart_ptr_for_overwrite}@ 202002L // also in \libheader{memory}

#define @\defnlibxname{cpp_lib_smart_ptr_owner_equality}@ 202306L // also in \libheader{memory}

#define @\defnlibxname{cpp_lib_source_location}@ 201907L // freestanding, also in \libheader{source_location}

#define @\defnlibxname{cpp_lib_span_initializer_list}@ 202311L // also in \libheader{span}

#define @\defnlibxname{cpp_lib_spanstream}@ 202106L // also in \libheader{spanstream}

#define @\defnlibxname{cpp_lib_ssize}@ 201902L // freestanding, also in \libheader{iterator}

\indexlibraryglobal{unexpect_t}%

\indexlibraryglobal{unexpect}%

\begin{codeblock}

namespace std {

// \ref{expected.unexpected}, class template \tcode{unexpected}

template<class E> class unexpected;

inline constexpr unexpect_t unexpect{};

// \ref{expected.expected}, class template \tcode{expected}

// \ref{expected.void}, partial specialization of \tcode{expected} for \tcode{void} types

}

\end{codeblock}

constexpr T&& operator*() && noexcept;

constexpr explicit operator bool() const noexcept;

constexpr bool has_value() const noexcept;

constexpr const E& error() const & noexcept;

constexpr E& error() & noexcept;

constexpr const E&& error() const && noexcept;

constexpr explicit operator bool() const noexcept;

constexpr bool has_value() const noexcept;

constexpr void operator*() const noexcept;

constexpr const E& error() const & noexcept;

constexpr E& error() & noexcept;

constexpr const E&& error() const && noexcept;