<section xmlns="http://docbook.org/ns/docbook" version="5.0"
xml:id="status.iso.2023" xreflabel="Status C++ 2023">
<?dbhtml filename="status_iso_cxx2023.html"?>
<info><title>C++ 2023</title>
<keywordset>
<keyword>ISO C++</keyword>
<keyword>2023</keyword>
</keywordset>
</info>
<para>
In this implementation the <literal>-std=gnu++23</literal> or
<literal>-std=c++23</literal> flag must be used to enable language
and library
features. See <link linkend="manual.intro.using.flags">dialect</link>
options. The pre-defined symbol
<constant>__cplusplus</constant> is used to check for the
presence of the required flag.
</para>
<para>
This section describes the C++23 and library TS support in mainline GCC,
not in any particular release.
</para>
<para>
The following table lists new library features that have been accepted into
the C++23 working draft. The "Proposal" column provides a link to the
ISO C++ committee proposal that describes the feature, while the "Status"
column indicates the first version of GCC that contains an implementation of
this feature (if it has been implemented).
A dash (—) in the status column indicates that the changes in the proposal
either do not affect the code in libstdc++, or the changes are not required for conformance.
The "SD-6 Feature Test / Notes" column shows the corresponding macro or header from
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations">SD-6:
Feature-testing recommendations for C++</link> (where applicable)
or any notes about the implementation.
</para>
<table frame="all" xml:id="table.cxx23_features">
<title>C++ 2023 Library Features</title>
<tgroup cols="4" align="left" colsep="0" rowsep="1">
<colspec colname="c1"/>
<colspec colname="c2"/>
<colspec colname="c3"/>
<colspec colname="c4"/>
<thead>
<row>
<entry>Library Feature</entry>
<entry>Proposal</entry>
<entry>Status</entry>
<entry>SD-6 Feature Test / Notes</entry>
</row>
</thead>
<tbody>
<row>
<entry namest="c1" nameend="c4" align="left">
<emphasis role="bold">Ranges and Views</emphasis>
</entry>
</row>
<row>
<entry> Range constructor for std::string_view </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1989r2.pdf">
P1989R2
</link>
</entry>
<entry align="center"> 11.1 </entry>
<entry />
</row>
<row>
<entry> <code>join_view</code> should join all views of ranges </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2328r1.html">
P2328R1
</link>
</entry>
<entry align="center"> 11.2 </entry>
<entry />
</row>
<row>
<entry> Clarifying range adaptor objects </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2281r1.html">
P2281R1
</link>
</entry>
<entry align="center"> 11.1 </entry>
<entry />
</row>
<row>
<entry> Views should not be required to be default constructible </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2325r3.html">
P2325R3
</link>
</entry>
<entry align="center"> 11.3 </entry>
<entry> <code>__cpp_lib_ranges >= 202106L</code> </entry>
</row>
<row>
<entry> Conditionally borrowed ranges </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2017r1.html">
P2017R1
</link>
</entry>
<entry align="center"> 11.1 </entry>
<entry />
</row>
<row>
<entry> Require <code>span</code> & <code>basic_string_view</code> to be Trivially Copyable </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2251r1.pdf">
P2251R1
</link>
</entry>
<entry align="center"> Yes </entry>
<entry />
</row>
<row>
<entry> Repairing input range adaptors and counted_iterator </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2259r1.html">
P2259R1
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry />
</row>
<row>
<entry> Superior String Splitting </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2210r2.html">
P2210R2
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry />
</row>
<row>
<entry> What is a <code>view</code>? </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2415r2.html">
P2415R2
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_ranges >= 202110L</code> </entry>
</row>
<row>
<entry> Fix istream_view </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2432r1.pdf">
P2432R1
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> <code>starts_with</code> and <code>ends_with</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1659r3.html">
P1659R3
</link>
</entry>
<entry align="center"> </entry>
<entry> <code>__cpp_lib_ranges_starts_ends_with >= 202106L</code> </entry>
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> <code>zip</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2321r2.html">
P2321R2
</link>
</entry>
<entry align="center"> </entry>
<entry> <code>__cpp_lib_ranges_zip >= 202110L</code> </entry>
</row>
<row>
<entry namest="c1" nameend="c4" align="left">
<emphasis role="bold">Compile-time programming</emphasis>
</entry>
</row>
<row>
<entry> A proposal for a type trait to detect scoped enumerations </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1048r1.pdf">
P1048R1
</link>
</entry>
<entry align="center"> 11.1 </entry>
<entry> <code>__cpp_lib_is_scoped_enum >= 202011L</code> </entry>
</row>
<row>
<entry> std::to_underlying for enumerations </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1682r3.html">
P1682R3
</link>
</entry>
<entry align="center"> 11.1 </entry>
<entry> <code>__cpp_lib_to_underlying >= 202102L</code> </entry>
</row>
<row>
<entry> Missing constexpr in std::optional and std::variant </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2231r1.html">
P2231R1
</link>
</entry>
<entry align="center">
<informaltable colsep="0" rowsep="0" rowheader="norowheader" frame="none"><tgroup cols="1"><tbody>
<row><entry> 11.3 (<code>optional</code>) </entry></row>
<row><entry> 12.1 (<code>variant</code>) </entry></row>
</tbody></tgroup></informaltable>
</entry>
<entry>
<informaltable colsep="0" rowsep="0" rowheader="norowheader" frame="none"><tgroup cols="1"><tbody>
<row><entry> <code>__cpp_lib_constexpr_optional >= 202106L</code> </entry></row>
<row><entry> <code>__cpp_lib_variant >= 202106L</code> </entry></row>
</tbody></tgroup></informaltable>
</entry>
</row>
<row>
<entry> Making <code>std::unique_ptr</code> constexpr </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2273r3.pdf">
P2273R3
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_constexpr_memory >= 202202L</code> </entry>
</row>
<row>
<entry> Making <code>std::type_info::operator==</code> constexpr </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1328r1.html">
P1328R1
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_constexpr_typeinfo >= 202106L</code> </entry>
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> constexpr for <code><cmath></code> and <code><cstdlib></code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p0533r9.pdf">
P0533R9
</link>
</entry>
<entry align="center"> </entry>
<entry> <code>__cpp_lib_constexpr_cmath >= 202202L</code> </entry>
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Deprecate std::aligned_storage and std::aligned_union </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1413r3.pdf">
P1413R3
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> A type trait to detect reference binding to temporary </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2255r2.html">
P2255R2
</link>
</entry>
<entry align="center"> </entry>
<entry> <code>__cpp_lib_reference_from_temporary >= 202202L</code> </entry>
</row>
<row>
<entry namest="c1" nameend="c4" align="left">
<emphasis role="bold">Strings and text</emphasis>
</entry>
</row>
<row>
<entry> string contains function </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1679r3.html">
P1679R3
</link>
</entry>
<entry align="center"> 11.1 </entry>
<entry> <code>__cpp_lib_string_contains >= 202011L</code> </entry>
</row>
<row>
<entry> Prohibit std::basic_string and std::basic_string_view construction from nullptr </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2166r1.html">
P2166R1
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry />
</row>
<row>
<entry> basic_string::resize_and_overwrite </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1072r10.html">
P1072R10
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_resize_and_overwrite >= 202110L</code> </entry>
</row>
<row>
<entry> A strstream replacement using span<charT> as buffer </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p0448r4.pdf">
P0448R4
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_spanstream >= 202106L</code> </entry>
</row>
<row>
<entry namest="c1" nameend="c4" align="left">
<emphasis role="bold">Containers</emphasis>
</entry>
</row>
<row>
<entry> Iterator pair constructors for stack and queue </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1425r4.pdf">
P1425R4
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_adaptor_iterator_pair_constructor >= 202106L</code> </entry>
</row>
<row>
<entry> Stop overconstraining allocators in container deduction guides </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1518r2.html">
P1518R2
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Heterogeneous erasure overloads for associative containers </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2077r3.html">
P2077R3
</link>
</entry>
<entry align="center"> </entry>
<entry> <code>__cpp_lib_associative_heterogeneous_erasure >= 202110L</code> </entry>
</row>
<row>
<entry namest="c1" nameend="c4" align="left">
<emphasis role="bold">Miscellaneous</emphasis>
</entry>
</row>
<row>
<entry> Inheriting from <code>std::variant</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2162r2.html">
P2162R2
</link>
</entry>
<entry align="center"> 11.3 </entry>
<entry> <code>__cpp_lib_variant >= 202102L</code> </entry>
</row>
<row>
<entry> Printing <code>volatile</code> Pointers </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1147r1.html">
P1147R1
</link>
</entry>
<entry align="center"> 11.3 </entry>
<entry/>
</row>
<row>
<entry> A Proposal to add stacktrace library </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p0881r7.html">
P0881R7
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_stacktrace >= 202011L</code> </entry>
</row>
<row>
<entry> Add a pmr alias for std::stacktrace </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2301r1.html">
P2301R1
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry />
</row>
<row>
<entry> <code>std::expected</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p0323r12.html">
P0323R12
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_expected >= 202202L</code> </entry>
</row>
<row>
<entry> Monadic operations for std::optional </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p0798r8.html">
P0798R8
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_optional >= 202110L</code> </entry>
</row>
<row>
<entry> <code>move_only_function</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p0288r9.html">
P0288R9
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_move_only_function >= 202110L</code> </entry>
</row>
<row>
<entry> <code>invoke_r</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2136r3.html">
P2136R3
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_invoke_r >= 202106L</code> </entry>
</row>
<row>
<entry> Byteswapping for fun&&nuf </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1272r4.html">
P1272R4
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_byteswap >= 202110L</code> </entry>
</row>
<row>
<entry> Function to mark unreachable code </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p0627r6.pdf">
P0627R6
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_unreachable >= 202202L</code> </entry>
</row>
<row>
<entry> Add a conditional noexcept specification to std::exchange </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2401r0.html">
P2401R0
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry />
</row>
<row>
<entry> Support C atomics in C++ </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p0943r6.html">
P0943R6
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry> <code>__cpp_lib_stdatomic_h >= 202011L</code> </entry>
</row>
<row>
<entry> Clarifying the status of the "C headers" </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2340r1.html">
P2340R1
</link>
</entry>
<entry align="center"> Yes </entry>
<entry />
</row>
<row>
<entry> Relax Requirements for time_point::clock </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p2212r2.html">
P2212R2
</link>
</entry>
<entry align="center"> Yes </entry>
<entry />
</row>
<row>
<entry> Removing Garbage Collection Support </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2186r2.html">
P2186R2
</link>
</entry>
<entry align="center"> 12.1 </entry>
<entry />
</row>
<row>
<entry> Easy [utilities], [ranges], and [iterators] </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p1642r11.html">
P1642R11
</link>
</entry>
<entry align="center"> 13.1 </entry>
<entry />
</row>
</tbody>
</tgroup>
</table>
</section>