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Document C++20 library status 

* doc/xml/manual/intro.xml: Include new section.
	* doc/xml/manual/status_cxx2017.xml: Document more
	implementation-defined properties of the library.
	* doc/xml/manual/status_cxx2020.xml: Document C++2a status.
	* doc/html/*: Regenerate.

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2019-01-11 Jonathan Wakely <jwakely@redhat.com>
* doc/xml/manual/intro.xml: Include new section.
* doc/xml/manual/status_cxx2017.xml: Document more
implementation-defined properties of the library.
* doc/xml/manual/status_cxx2020.xml: Document C++2a status.
* doc/html/*: Regenerate.
* include/bits/refwrap.h [__cplusplus > 201703L]
(_Refwrap_base_arg1, _Refwrap_base_arg2, _Reference_wrapper_base)
(_Reference_wrapper_base_memfun): Do not define for C++2a.

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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 1. Status</title><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="intro.html" title="Part I.  Introduction" /><link rel="prev" href="intro.html" title="Part I.  Introduction" /><link rel="next" href="license.html" title="License" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 1. Status</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="intro.html">Prev</a> </td><th width="60%" align="center">Part I. 
Introduction
</th><td width="20%" align="right"> <a accesskey="n" href="license.html">Next</a></td></tr></table><hr /></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="manual.intro.status"></a>Chapter 1. Status</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="status.html#manual.intro.status.iso">Implementation Status</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#status.iso.1998">C++ 1998/2003</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.1998.status">Implementation Status</a></span></dt><dt><span class="section"><a href="status.html#iso.1998.specific">Implementation Specific Behavior</a></span></dt></dl></dd><dt><span class="section"><a href="status.html#status.iso.2011">C++ 2011</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.2011.specific">Implementation Specific Behavior</a></span></dt></dl></dd><dt><span class="section"><a href="status.html#status.iso.2014">C++ 2014</a></span></dt><dt><span class="section"><a href="status.html#status.iso.2017">C++ 2017</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.2017.specific">Implementation Specific Behavior</a></span></dt></dl></dd><dt><span class="section"><a href="status.html#status.iso.tr1">C++ TR1</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.tr1.specific">Implementation Specific Behavior</a></span></dt></dl></dd><dt><span class="section"><a href="status.html#status.iso.tr24733">C++ TR 24733</a></span></dt><dt><span class="section"><a href="status.html#status.iso.specfun">C++ IS 29124</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.specfun.specific">Implementation Specific Behavior</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="license.html">License</a></span></dt><dd><dl><dt><span class="section"><a href="license.html#manual.intro.status.license.gpl">The Code: GPL</a></span></dt><dt><span class="section"><a href="license.html#manual.intro.status.license.fdl">The Documentation: GPL, FDL</a></span></dt></dl></dd><dt><span class="section"><a href="bugs.html">Bugs</a></span></dt><dd><dl><dt><span class="section"><a href="bugs.html#manual.intro.status.bugs.impl">Implementation Bugs</a></span></dt><dt><span class="section"><a href="bugs.html#manual.intro.status.bugs.iso">Standard Bugs</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.status.iso"></a>Implementation Status</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="status.iso.1998"></a>C++ 1998/2003</h3></div></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="iso.1998.status"></a>Implementation Status</h4></div></div></div><p>
</th><td width="20%" align="right"> <a accesskey="n" href="license.html">Next</a></td></tr></table><hr /></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="manual.intro.status"></a>Chapter 1. Status</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="status.html#manual.intro.status.iso">Implementation Status</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#status.iso.1998">C++ 1998/2003</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.1998.status">Implementation Status</a></span></dt><dt><span class="section"><a href="status.html#iso.1998.specific">Implementation Specific Behavior</a></span></dt></dl></dd><dt><span class="section"><a href="status.html#status.iso.2011">C++ 2011</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.2011.specific">Implementation Specific Behavior</a></span></dt></dl></dd><dt><span class="section"><a href="status.html#status.iso.2014">C++ 2014</a></span></dt><dt><span class="section"><a href="status.html#status.iso.2017">C++ 2017</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.2017.specific">Implementation Specific Behavior</a></span></dt></dl></dd><dt><span class="section"><a href="status.html#status.iso.2020">C++ 202a</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.2020.specific">Implementation Specific Behavior</a></span></dt></dl></dd><dt><span class="section"><a href="status.html#status.iso.tr1">C++ TR1</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.tr1.specific">Implementation Specific Behavior</a></span></dt></dl></dd><dt><span class="section"><a href="status.html#status.iso.tr24733">C++ TR 24733</a></span></dt><dt><span class="section"><a href="status.html#status.iso.specfun">C++ IS 29124</a></span></dt><dd><dl><dt><span class="section"><a href="status.html#iso.specfun.specific">Implementation Specific Behavior</a></span></dt></dl></dd></dl></dd><dt><span class="section"><a href="license.html">License</a></span></dt><dd><dl><dt><span class="section"><a href="license.html#manual.intro.status.license.gpl">The Code: GPL</a></span></dt><dt><span class="section"><a href="license.html#manual.intro.status.license.fdl">The Documentation: GPL, FDL</a></span></dt></dl></dd><dt><span class="section"><a href="bugs.html">Bugs</a></span></dt><dd><dl><dt><span class="section"><a href="bugs.html#manual.intro.status.bugs.impl">Implementation Bugs</a></span></dt><dt><span class="section"><a href="bugs.html#manual.intro.status.bugs.iso">Standard Bugs</a></span></dt></dl></dd></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.status.iso"></a>Implementation Status</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="status.iso.1998"></a>C++ 1998/2003</h3></div></div></div><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="iso.1998.status"></a>Implementation Status</h4></div></div></div><p>
This status table is based on the table of contents of ISO/IEC 14882:2003.
</p><p>
This page describes the C++ support in mainline GCC SVN, not in any
@ -890,25 +890,36 @@ and test for <code class="code">__STDCPP_MATH_SPEC_FUNCS__ &gt;= 201003L</code>.
Specific Behavior</a> and <a class="link" href="status.html#iso.2011.specific" title="Implementation Specific Behavior">C++
2011 Implementation Specific Behavior</a>. This section only
documents behaviour which is new in the 2017 standard.
</p><p>
<span class="emphasis"><em>20.5.1.2 [headers]</em></span>
Whether names from Annex K are declared by C++ headers depends on
whether the underlying C library supports Annex K and declares the
names. For the GNU C library, there is no Annex K support and so
none of its names are declared by C++ headers.
</p><p>
<span class="emphasis"><em>23.6.5 [optional.bad_optional_access]</em></span>
<code class="code">what()</code> returns <code class="literal">"bad optional access"</code>.
</p><p>
<span class="emphasis"><em>23.7.3 [variant.variant]</em></span>
Whether <code class="classname">variant</code> supports over-aligned types
should be documented here.
<code class="classname">variant</code> supports over-aligned types.
</p><p>
<span class="emphasis"><em>23.7.10 [variant.bad.access]</em></span>
<code class="code">what()</code> returns <code class="literal">"Unexpected index"</code>.
</p><p>
<span class="emphasis"><em>23.12.5.2 [memory.resource.pool.options]</em></span>
The limits for maximum number of blocks and largest allocation size
supported by <code class="classname">pool_options</code> should be documented
here.
Let S equal <code class="code">numeric_limits&lt;size_t&gt;::digits</code>.
The limit for maximum number of blocks in a chunk is given by
<span class="mathphrase">2<sup>N</sup>-1</span>,
where N is <span class="mathphrase">min(19, 3 + S/2)</span>.
The largest allocation size that will be allocated from a pool is
<span class="mathphrase">2<sup>22</sup></span>
when <span class="mathphrase">S &gt; 20</span>,
otherwise 3072 when <span class="mathphrase">S &gt; 16</span>,
otherwise 768.
</p><p>
<span class="emphasis"><em>23.12.6.1 [memory.resource.monotonic.buffer.ctor]</em></span>
The default <code class="code">next_buffer_size</code> and growth factor should
be documented here.
The default <code class="code">next_buffer_size</code> is <code class="code">128 * sizeof(void*)</code>.
The default growth factor is <code class="code">1.5</code>.
</p><p>
<span class="emphasis"><em>23.15.4.3 [meta.unary.prop]</em></span>
The predicate condition for
@ -950,11 +961,363 @@ and test for <code class="code">__STDCPP_MATH_SPEC_FUNCS__ &gt;= 201003L</code>.
on some targets.
</p><p>
<span class="emphasis"><em>30.10.5 [fs.filesystem.syn]</em></span>
The clock used for file times is
<code class="classname">std::chrono::system_clock</code>.
The clock used for file times is an unspecified type
with a signed 64-bit representation, capable of representing
timestamps with nanosecond resolution. The clock's epoch is
unspecified, but is not the same as the system clock's epoch.
</p><p>
<span class="emphasis"><em>30.10.7.1 [fs.path.generic]</em></span>
dot-dot in the root-directory refers to the root-directory itself.
On Windows, a drive specifier such as <code class="code">"C:"</code> or
<code class="code">"z:"</code> is treated as a root-name. On Cygwin, a path
that begins with two successive directory separators is a
root-name. Otherwise (for POSIX-like systems other than Cygwin),
the implementation-defined root-name is an unspecified string
which does not appear in any pathnames.
</p><p>
<span class="emphasis"><em>30.10.10.1 [fs.enum.path.format]</em></span>
The character sequence is always interpreted in the native pathname
format.
</p><p>
<span class="emphasis"><em>30.10.15.4 [fs.op.file_size]</em></span>
If <code class="code">!is_regular_file(p)</code>, an error is reported.
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="status.iso.2020"></a>C++ 202a</h3></div></div></div><p>
In this implementation the <code class="literal">-std=gnu++2a</code> or
<code class="literal">-std=c++2a</code> flag must be used to enable language
and library
features. See <a class="link" href="using.html#manual.intro.using.flags" title="Command Options">dialect</a>
options. The pre-defined symbol
<code class="constant">__cplusplus</code> is used to check for the
presence of the required flag.
</p><p>
This section describes the C++20 and library TS support in mainline GCC SVN,
not in any particular release.
</p><p>
The following table lists new library features that have been accepted into
the C++2a 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).
The "SD-6 Feature Test" column shows the corresponding macro or header from
<a class="link" href="https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations" target="_top">SD-6:
Feature-testing recommendations for C++</a>.
</p><div class="table"><a id="table.cxx20_status"></a><p class="title"><strong>Table 1.7. C++ 2020 Implementation Status</strong></p><div class="table-contents"><table class="table" summary="C++ 2020 Implementation Status" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /></colgroup><thead><tr><th align="left">Library Feature</th><th align="left">Proposal</th><th align="left">Status</th><th align="left">SD-6 Feature Test</th></tr></thead><tbody><tr><td align="left"> Endian just Endian </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0463r1.html" target="_top">
P0463R1
</a>
</td><td align="center"> 8.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Extending <code class="code">make_shared</code> to Support Arrays </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0674r1.html" target="_top">
P0674R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Floating Point Atomic </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0020r6.html" target="_top">
P0020R6
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> C++ Synchronized Buffered Ostream </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0053r7.pdf" target="_top">
P0053R7
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Add constexpr modifiers to functions in <code class="code">&lt;algorithm&gt;</code> and <code class="code">&lt;utility&gt;</code> Headers </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0202r3.html" target="_top">
P0202R3
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> Constexpr for <code class="code">std::complex</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0415r1.html" target="_top">
P0415R1
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Make <code class="code">std::memory_order</code> a scoped enumeration </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0439r0.html" target="_top">
P0439R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> String Prefix and Suffix Checking </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0457r2.html" target="_top">
P0457R2
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr><td align="left"> Transformation Trait <code class="code">remove_cvref</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0550r2.pdf" target="_top">
P0550R2
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> <code class="code">nodiscard</code> in the Library </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0600r1.pdf" target="_top">
P0600R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> de-pessimize legacy algorithms with <code class="code">std::move</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0616r0.pdf" target="_top">
P0616R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> Utility to convert a pointer to a raw pointer </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0653r2.html" target="_top">
P0653R2
</a>
</td><td align="center"> 8.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Atomic <code class="code">shared_ptr</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0718r2.html" target="_top">
P0718R2
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Deprecate POD </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0767r1.html" target="_top">
P0767R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Library Support for the Spaceship (Comparison) Operator </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0768r1.pdf" target="_top">
P0768R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Treating Unnecessary <code class="code">decay</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0777r1.pdf" target="_top">
P0777R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> <code class="code">&lt;span&gt;</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0122r7.pdf" target="_top">
P0122R7
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Extending chrono to Calendars and Time Zones </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html" target="_top">
P0355R7
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Thou Shalt Not Specialize std Function Templates! </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0551r3.pdf" target="_top">
P0551R3
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Manipulators for C++ Synchronized Buffered Ostream </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0753r2.pdf" target="_top">
P0753R2
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> <code class="code">&lt;version&gt;</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0754r2.pdf" target="_top">
P0754R2
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Comparing Unordered Containers </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0809r0.pdf" target="_top">
P0809R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Constexpr iterator requirements </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0858r0.html" target="_top">
P0858R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Symmetry for spaceship </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0905r1.html" target="_top">
P0905R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> <code class="code">string::reserve</code> Should Not Shrink </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0966r1.html" target="_top">
P0966R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Atomic Ref </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0019r8.html" target="_top">
P0019R8
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> Checking for Existence of an Element in Associative Containers </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0458r2.html" target="_top">
P0458R2
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr><td align="left"> LWG 2511: guaranteed copy elision for piecewise construction </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0475r1.html" target="_top">
P0475R1
</a>
</td><td align="center"> 7.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Bit-casting object representations </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0476r2.html" target="_top">
P0476R2
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> The Curious Case of Padding Bits, Featuring Atomic Compare-and-Exchange </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0528r3.html" target="_top">
P0528R3
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Support for contract based programming in C++ </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0542r5.html" target="_top">
P0542R5
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> Integral power-of-2 operations </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0556r3.html" target="_top">
P0556R3
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Reviewing Deprecated Facilities of C++17 for C++20 </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0619r4.html" target="_top">
P0619R4
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> Improving the Return Value of Erase-Like Algorithms </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0646r1.pdf" target="_top">
P0646R1
</a>
</td><td align="center"> 9.1 </td><td align="left"> <code class="code">__cpp_lib_list_remove_return_type &gt;= 201806L</code> </td></tr><tr><td align="left"> Efficient sized delete for variable sized classes </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0722r3.html" target="_top">
P0722R3
</a>
</td><td align="center"> 9.1 </td><td align="left"> <code class="code">__cpp_lib_destroying_delete &gt;= 201806L</code> </td></tr><tr><td align="left"> Implicit conversion traits and utility functions </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0758r1.html" target="_top">
P0758R1
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr><td align="left"> <code class="code">fpos</code> Requirements </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0759r1.html" target="_top">
P0759R1
</a>
</td><td align="center"> Note 1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Add <code class="code">shift</code> to <code class="code">&lt;algorithm&gt;</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0769r2.pdf" target="_top">
P0769R2
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Standard Library Specification in a Concepts and Contracts World </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0788r3.pdf" target="_top">
P0788R3
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Constexpr for <code class="code">swap</code> and swap related functions </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0879r0.html" target="_top">
P0879R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> The <code class="code">identity</code> metafunction </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0887r1.pdf" target="_top">
P0887R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> <code class="code">explicit(bool)</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0892r2.html" target="_top">
P0892R2
</a>
</td><td align="center"> Note 1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Standard Library Concepts </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0898r3.pdf" target="_top">
P0898R3
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> Eradicating unnecessarily explicit default constructors from the standard library </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0935r0.html" target="_top">
P0935R0
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr><td align="left"> Integrating feature-test macros into the C++ WD </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0941r2.html" target="_top">
P0941R2
</a>
</td><td align="center"> 5.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> <code class="code">constexpr</code> comparison operators for <code class="code">std::array</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1023r0.pdf" target="_top">
P1023R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Update The Reference To The Unicode Standard </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1025r1.html" target="_top">
P1025R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Consistency improvements for <code class="code">&lt;=&gt;</code> and other comparison operators </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1120r0.html" target="_top">
P1120R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> <code class="code">unwrap_ref_decay</code> and <code class="code">unwrap_reference</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0318r1.pdf" target="_top">
P0318R1
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Simplified partial function application </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0356r5.html" target="_top">
P0356R5
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> <code class="code">reference_wrapper</code> for incomplete types </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0357r3.html" target="_top">
P0357R3
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> <code class="code">char8_t</code>: A type for UTF-8 characters and strings </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0482r6.html" target="_top">
P0482R6
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Fixing <code class="code">operator&gt;&gt;(basic_istream&amp;, CharT*)</code> (LWG 2499) </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0487r1.html" target="_top">
P0487R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Utility functions to implement uses-allocator construction </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0591r4.pdf" target="_top">
P0591R4
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> P0595R2 <code class="code">std::is_constant_evaluated()</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0595r2.html" target="_top">
P0595R2
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr><td align="left"> <code class="code">variant</code> and <code class="code">optional</code> should propagate copy/move triviality </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0602r4.html" target="_top">
P0602R4
</a>
</td><td align="center"> 8.3 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> A sane <code class="code">variant</code> converting constructor </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0608r3.html" target="_top">
P0608R3
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> <code class="code">visit&lt;R&gt;</code>: Explicit Return Type for <code class="code">visit</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0655r1.pdf" target="_top">
P0655R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> <code class="code">std::function</code> move constructor should be <code class="code">noexcept</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0771r1.pdf" target="_top">
P0771R1
</a>
</td><td align="center"> 7.2 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> The One Ranges Proposal </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0896r4.pdf" target="_top">
P0896R4
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> P0899R1 - LWG 3016 is not a defect </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0899r1.html" target="_top">
P0899R1
</a>
</td><td align="center"> 7.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Heterogeneous lookup for unordered containers </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0919r3.html" target="_top">
P0919R3
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> <code class="code">&lt;chrono&gt;</code> <code class="code">zero()</code>, <code class="code">min()</code>, and <code class="code">max()</code> should be <code class="code">noexcept</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0972r0.pdf" target="_top">
P0972R0
</a>
</td><td align="center"> 9.1 </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Constexpr in <code class="code">std::pointer_traits</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1006r1.pdf" target="_top">
P1006R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> <code class="code">std::assume_aligned</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1007r3.pdf" target="_top">
P1007R3
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Smart pointer creation with default initialization </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1020r1.html" target="_top">
P1020R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Misc constexpr bits </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1032r1.html" target="_top">
P1032R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Should Span be Regular? </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1085r2.md" target="_top">
P1085R2
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Editorial Guidance for merging P0019r8 and P0528r3 </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1123r0.html" target="_top">
P1123R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Cleaning up Clause 20 </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1148r0.pdf" target="_top">
P1148R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Make stateful allocator propagation more consistent for <code class="code">operator+(basic_string)</code> </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1165r1.html" target="_top">
P1165R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr><td align="left"> Adopt Consistent Container Erasure from Library Fundamentals 2 for C++20 </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1209r0.html" target="_top">
P1209R0
</a>
</td><td align="center"> 9.1 </td><td align="left"> <code class="code">__cpp_lib_erase_if &gt;= 201811L</code> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Completing the Rebase of Library Fundamentals, Version 3, Working Draft </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1210r0.html" target="_top">
P1210R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Alternative Wording for P0907R4 Signed Integers are Two's Complement </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1236r1.html" target="_top">
P1236R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Remove CommonReference requirement from StrictWeakOrdering (a.k.a Fixing Relations) </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1248r1.html" target="_top">
P1248R1
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#C8B0B0"><td align="left"> Improving Completeness Requirements for Type Traits </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1285r0.pdf" target="_top">
P1285R0
</a>
</td><td align="center"> </td><td align="left"> </td></tr><tr bgcolor="#B0B0B0"><td align="left"> Missing feature test macros </td><td align="left">
<a class="link" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1353r0.html" target="_top">
P1353R0
</a>
</td><td align="center"> Partial </td><td align="left"> </td></tr></tbody></table></div></div><br class="table-break" /><p>
Note 1: The changes in the proposal either do not affect the code in libstdc++,
or the changes are not required for conformance.
</p><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="iso.2020.specific"></a>Implementation Specific Behavior</h4></div></div></div><p>For behaviour which is also specified by previous standards,
see <a class="link" href="status.html#iso.1998.specific" title="Implementation Specific Behavior">C++ 1998/2003 Implementation
Specific Behavior</a>, <a class="link" href="status.html#iso.2011.specific" title="Implementation Specific Behavior">C++
2011 Implementation Specific Behavior</a> and <a class="link" href="status.html#iso.2017.specific" title="Implementation Specific Behavior">C++ 2017 Implementation Specific
Behavior</a>.
This section only documents behaviour which is new in the 202a draft.
</p></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="status.iso.tr1"></a>C++ TR1</h3></div></div></div><p>
This table is based on the table of contents of ISO/IEC DTR 19768
Doc No: N1836=05-0096 Date: 2005-06-24
@ -966,7 +1329,7 @@ In this implementation the header names are prefixed by
</p><p>
This page describes the TR1 support in mainline GCC SVN, not in any particular
release.
</p><div class="table"><a id="table.tr1_status"></a><p class="title"><strong>Table 1.7. C++ TR1 Implementation Status</strong></p><div class="table-contents"><table class="table" summary="C++ TR1 Implementation Status" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /></colgroup><thead><tr><th align="left">Section</th><th align="left">Description</th><th align="left">Status</th><th align="left">Comments</th></tr></thead><tbody><tr><td align="left"><span class="emphasis"><em>2</em></span></td><td colspan="3" align="left"><span class="emphasis"><em>General Utilities</em></span></td></tr><tr><td align="left">2.1</td><td align="left">Reference wrappers</td><td align="left"> </td><td align="left"> </td></tr><tr><td align="left">2.1.1</td><td align="left">Additions to header <code class="code">&lt;functional&gt;</code> synopsis</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2</td><td align="left">Class template <code class="code">reference_wrapper</code></td><td align="left"> </td><td align="left"> </td></tr><tr><td align="left">2.1.2.1</td><td align="left"><code class="code">reference_wrapper</code> construct/copy/destroy</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2.2</td><td align="left"><code class="code">reference_wrapper</code> assignment</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2.3</td><td align="left"><code class="code">reference_wrapper</code> access</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2.4</td><td align="left"><code class="code">reference_wrapper</code> invocation</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2.5</td><td align="left"><code class="code">reference_wrapper</code> helper functions</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.2</td><td align="left">Smart pointers</td><td align="left"> </td><td align="left"> </td></tr><tr><td align="left">2.2.1</td><td align="left">Additions to header <code class="code">&lt;memory&gt;</code> synopsis</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.2.2</td><td align="left">Class <code class="code">bad_weak_ptr</code></td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.2.3</td><td align="left">Class template <code class="code">shared_ptr</code></td><td align="left"> </td><td align="left">
</p><div class="table"><a id="table.tr1_status"></a><p class="title"><strong>Table 1.8. C++ TR1 Implementation Status</strong></p><div class="table-contents"><table class="table" summary="C++ TR1 Implementation Status" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /></colgroup><thead><tr><th align="left">Section</th><th align="left">Description</th><th align="left">Status</th><th align="left">Comments</th></tr></thead><tbody><tr><td align="left"><span class="emphasis"><em>2</em></span></td><td colspan="3" align="left"><span class="emphasis"><em>General Utilities</em></span></td></tr><tr><td align="left">2.1</td><td align="left">Reference wrappers</td><td align="left"> </td><td align="left"> </td></tr><tr><td align="left">2.1.1</td><td align="left">Additions to header <code class="code">&lt;functional&gt;</code> synopsis</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2</td><td align="left">Class template <code class="code">reference_wrapper</code></td><td align="left"> </td><td align="left"> </td></tr><tr><td align="left">2.1.2.1</td><td align="left"><code class="code">reference_wrapper</code> construct/copy/destroy</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2.2</td><td align="left"><code class="code">reference_wrapper</code> assignment</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2.3</td><td align="left"><code class="code">reference_wrapper</code> access</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2.4</td><td align="left"><code class="code">reference_wrapper</code> invocation</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.1.2.5</td><td align="left"><code class="code">reference_wrapper</code> helper functions</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.2</td><td align="left">Smart pointers</td><td align="left"> </td><td align="left"> </td></tr><tr><td align="left">2.2.1</td><td align="left">Additions to header <code class="code">&lt;memory&gt;</code> synopsis</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.2.2</td><td align="left">Class <code class="code">bad_weak_ptr</code></td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">2.2.3</td><td align="left">Class template <code class="code">shared_ptr</code></td><td align="left"> </td><td align="left">
<p>
Uses code from
<a class="link" href="http://www.boost.org/libs/smart_ptr/shared_ptr.htm" target="_top">boost::shared_ptr</a>.
@ -987,7 +1350,7 @@ decimal floating-point arithmetic
</p><p>
This page describes the TR 24733 support in mainline GCC SVN, not in any
particular release.
</p><div class="table"><a id="table.decfp_status"></a><p class="title"><strong>Table 1.8. C++ TR 24733 Implementation Status</strong></p><div class="table-contents"><table class="table" summary="C++ TR 24733 Implementation Status" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /></colgroup><thead><tr><th align="left">Section</th><th align="left">Description</th><th align="left">Status</th><th align="left">Comments</th></tr></thead><tbody><tr><td align="left">
</p><div class="table"><a id="table.decfp_status"></a><p class="title"><strong>Table 1.9. C++ TR 24733 Implementation Status</strong></p><div class="table-contents"><table class="table" summary="C++ TR 24733 Implementation Status" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /></colgroup><thead><tr><th align="left">Section</th><th align="left">Description</th><th align="left">Status</th><th align="left">Comments</th></tr></thead><tbody><tr><td align="left">
<span class="emphasis"><em>0</em></span>
</td><td colspan="3" align="left">
<span class="emphasis"><em>Introduction</em></span>
@ -1027,7 +1390,7 @@ non-strict modes (i.e. <code class="code">-std=gnu++NN</code> modes) the
hypergeometric functions and confluent hypergeometric functions
from TR1 are also provided, defined in namespace
<code class="code">__gnu_cxx</code>.
</p><div class="table"><a id="table.specfun_status"></a><p class="title"><strong>Table 1.9. C++ Special Functions Implementation Status</strong></p><div class="table-contents"><table class="table" summary="C++ Special Functions Implementation Status" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /></colgroup><thead><tr><th align="left">Section</th><th align="left">Description</th><th align="left">Status</th><th align="left">Comments</th></tr></thead><tbody><tr bgcolor="#B0B0B0"><td align="left">7</td><td align="left">Macro names</td><td align="left">Partial</td><td align="left">No diagnostic for inconsistent definitions of
</p><div class="table"><a id="table.specfun_status"></a><p class="title"><strong>Table 1.10. C++ Special Functions Implementation Status</strong></p><div class="table-contents"><table class="table" summary="C++ Special Functions Implementation Status" border="1"><colgroup><col align="left" class="c1" /><col align="left" class="c2" /><col align="left" class="c3" /><col align="left" class="c4" /></colgroup><thead><tr><th align="left">Section</th><th align="left">Description</th><th align="left">Status</th><th align="left">Comments</th></tr></thead><tbody><tr bgcolor="#B0B0B0"><td align="left">7</td><td align="left">Macro names</td><td align="left">Partial</td><td align="left">No diagnostic for inconsistent definitions of
<code class="code">__STDCPP_WANT_MATH_SPEC_FUNCS__</code></td></tr><tr><td align="left">8</td><td align="left">Mathematical special functions</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1</td><td align="left">Additions to header <code class="code">&lt;cmath&gt;</code> synopsis</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.1</td><td align="left">associated Laguerre polynomials</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.2</td><td align="left">associated Legendre functions</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.3</td><td align="left">beta function</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.4</td><td align="left">(complete) elliptic integral of the first kind</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.5</td><td align="left">(complete) elliptic integral of the second kind</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.6</td><td align="left">(complete) elliptic integral of the third kind</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.7</td><td align="left">regular modified cylindrical Bessel functions</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.8</td><td align="left">cylindrical Bessel functions (of the first kind)</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.9</td><td align="left">irregular modified cylindrical Bessel functions</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.10</td><td align="left">cylindrical Neumann functions</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.11</td><td align="left">(incomplete) elliptic integral of the first kind</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.12</td><td align="left">(incomplete) elliptic integral of the second kind</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.13</td><td align="left">(incomplete) elliptic integral of the third kind</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.14</td><td align="left">exponential integral</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.15</td><td align="left">Hermite polynomials</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.16</td><td align="left">Laguerre polynomials</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.17</td><td align="left">Legendre polynomials</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.18</td><td align="left">Riemann zeta function</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.19</td><td align="left">spherical Bessel functions (of the first kind)</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.20</td><td align="left">spherical associated Legendre functions</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.1.21</td><td align="left">spherical Neumann functions</td><td align="left">Y</td><td align="left"> </td></tr><tr><td align="left">8.2</td><td align="left">Additions to header <code class="code">&lt;math.h&gt;</code></td><td align="left">Y</td><td align="left"> </td></tr><tr bgcolor="#B0B0B0"><td align="left">8.3</td><td align="left">The header <code class="code">&lt;ctgmath&gt;</code></td><td align="left">Partial</td><td align="left">Conflicts with C++ 2011 requirements.</td></tr><tr bgcolor="#C8B0B0"><td align="left">8.4</td><td align="left">The header <code class="code">&lt;tgmath.h&gt;</code></td><td align="left">N</td><td align="left">Conflicts with C++ 2011 requirements.</td></tr></tbody></table></div></div><br class="table-break" /><div class="section"><div class="titlepage"><div><div><h4 class="title"><a id="iso.specfun.specific"></a>Implementation Specific Behavior</h4></div></div></div><p>For behaviour which is specified by the 2011 standard,
see <a class="link" href="status.html#iso.2011.specific" title="Implementation Specific Behavior">C++ 2011 Implementation
Specific Behavior</a>. This section documents behaviour which

4
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@ -43,6 +43,10 @@
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" parse="xml" href="status_cxx2017.xml">
</xi:include>
<!-- Section 01.4 : Status C++ 2020 -->
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" parse="xml" href="status_cxx2020.xml">
</xi:include>
<!-- Section 01.5 : Status C++ TR1 -->
<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" parse="xml" href="status_cxxtr1.xml">
</xi:include>

50
libstdc++-v3/doc/xml/manual/status_cxx2017.xml
View File

@ -980,6 +980,14 @@ and test for <code>__STDCPP_MATH_SPEC_FUNCS__ >= 201003L</code>.
documents behaviour which is new in the 2017 standard.
</para>
<para>
<emphasis>20.5.1.2 [headers]</emphasis>
Whether names from Annex K are declared by C++ headers depends on
whether the underlying C library supports Annex K and declares the
names. For the GNU C library, there is no Annex K support and so
none of its names are declared by C++ headers.
</para>
<para>
<emphasis>23.6.5 [optional.bad_optional_access]</emphasis>
<code>what()</code> returns <literal>"bad optional access"</literal>.
@ -987,8 +995,7 @@ and test for <code>__STDCPP_MATH_SPEC_FUNCS__ >= 201003L</code>.
<para>
<emphasis>23.7.3 [variant.variant]</emphasis>
Whether <classname>variant</classname> supports over-aligned types
should be documented here.
<classname>variant</classname> supports over-aligned types.
</para>
<para>
@ -998,15 +1005,21 @@ and test for <code>__STDCPP_MATH_SPEC_FUNCS__ >= 201003L</code>.
<para>
<emphasis>23.12.5.2 [memory.resource.pool.options]</emphasis>
The limits for maximum number of blocks and largest allocation size
supported by <classname>pool_options</classname> should be documented
here.
Let S equal <code>numeric_limits&lt;size_t&gt;::digits</code>.
The limit for maximum number of blocks in a chunk is given by
<inlineequation><mathphrase>2<superscript>N</superscript>-1</mathphrase></inlineequation>,
where N is <inlineequation><mathphrase>min(19, 3 + S/2)</mathphrase></inlineequation>.
The largest allocation size that will be allocated from a pool is
<inlineequation><mathphrase>2<superscript>22</superscript></mathphrase></inlineequation>
when <inlineequation><mathphrase>S > 20</mathphrase></inlineequation>,
otherwise 3072 when <inlineequation><mathphrase>S > 16</mathphrase></inlineequation>,
otherwise 768.
</para>
<para>
<emphasis>23.12.6.1 [memory.resource.monotonic.buffer.ctor]</emphasis>
The default <code>next_buffer_size</code> and growth factor should
be documented here.
The default <code>next_buffer_size</code> is <code>128 * sizeof(void*)</code>.
The default growth factor is <code>1.5</code>.
</para>
<para>
@ -1067,13 +1080,32 @@ and test for <code>__STDCPP_MATH_SPEC_FUNCS__ >= 201003L</code>.
<para>
<emphasis>30.10.5 [fs.filesystem.syn]</emphasis>
The clock used for file times is
<classname>std::chrono::system_clock</classname>.
The clock used for file times is an unspecified type
with a signed 64-bit representation, capable of representing
timestamps with nanosecond resolution. The clock's epoch is
unspecified, but is not the same as the system clock's epoch.
</para>
<para>
<emphasis>30.10.7.1 [fs.path.generic]</emphasis>
dot-dot in the root-directory refers to the root-directory itself.
On Windows, a drive specifier such as <code>"C:"</code> or
<code>"z:"</code> is treated as a root-name. On Cygwin, a path
that begins with two successive directory separators is a
root-name. Otherwise (for POSIX-like systems other than Cygwin),
the implementation-defined root-name is an unspecified string
which does not appear in any pathnames.
</para>
<para>
<emphasis>30.10.10.1 [fs.enum.path.format]</emphasis>
The character sequence is always interpreted in the native pathname
format.
</para>
<para>
<emphasis>30.10.15.4 [fs.op.file_size]</emphasis>
If <code>!is_regular_file(p)</code>, an error is reported.
</para>

980
libstdc++-v3/doc/xml/manual/status_cxx2020.xml Normal file
View File

@ -0,0 +1,980 @@
<section xmlns="http://docbook.org/ns/docbook" version="5.0"
xml:id="status.iso.2020" xreflabel="Status C++ 2020">
<?dbhtml filename="status_iso_cxx2020.html"?>
<info><title>C++ 202a</title>
<keywordset>
<keyword>ISO C++</keyword>
<keyword>2020</keyword>
</keywordset>
</info>
<para>
In this implementation the <literal>-std=gnu++2a</literal> or
<literal>-std=c++2a</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++20 and library TS support in mainline GCC SVN,
not in any particular release.
</para>
<para>
The following table lists new library features that have been accepted into
the C++2a 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).
The "SD-6 Feature Test" 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>.
</para>
<table frame="all" xml:id="table.cxx20_status">
<title>C++ 2020 Implementation Status</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</entry>
</row>
</thead>
<tbody>
<row>
<entry> Endian just Endian </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0463r1.html">
P0463R1
</link>
</entry>
<entry align="center"> 8.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Extending <code>make_shared</code> to Support Arrays </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0674r1.html">
P0674R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Floating Point Atomic </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0020r6.html">
P0020R6
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> C++ Synchronized Buffered Ostream </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0053r7.pdf">
P0053R7
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Add constexpr modifiers to functions in <code>&lt;algorithm&gt;</code> and <code>&lt;utility&gt;</code> Headers </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0202r3.html">
P0202R3
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> Constexpr for <code>std::complex</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0415r1.html">
P0415R1
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Make <code>std::memory_order</code> a scoped enumeration </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0439r0.html">
P0439R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> String Prefix and Suffix Checking </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0457r2.html">
P0457R2
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<entry> Transformation Trait <code>remove_cvref</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0550r2.pdf">
P0550R2
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> <code>nodiscard</code> in the Library </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0600r1.pdf">
P0600R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> de-pessimize legacy algorithms with <code>std::move</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0616r0.pdf">
P0616R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> Utility to convert a pointer to a raw pointer </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0653r2.html">
P0653R2
</link>
</entry>
<entry align="center"> 8.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Atomic <code>shared_ptr</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0718r2.html">
P0718R2
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Deprecate POD </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0767r1.html">
P0767R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Library Support for the Spaceship (Comparison) Operator </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0768r1.pdf">
P0768R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Treating Unnecessary <code>decay</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0777r1.pdf">
P0777R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> <code>&lt;span&gt;</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0122r7.pdf">
P0122R7
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Extending chrono to Calendars and Time Zones </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0355r7.html">
P0355R7
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Thou Shalt Not Specialize std Function Templates! </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0551r3.pdf">
P0551R3
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Manipulators for C++ Synchronized Buffered Ostream </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0753r2.pdf">
P0753R2
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> <code>&lt;version&gt;</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0754r2.pdf">
P0754R2
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Comparing Unordered Containers </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0809r0.pdf">
P0809R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Constexpr iterator requirements </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0858r0.html">
P0858R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Symmetry for spaceship </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0905r1.html">
P0905R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> <code>string::reserve</code> Should Not Shrink </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0966r1.html">
P0966R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Atomic Ref </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0019r8.html">
P0019R8
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> Checking for Existence of an Element in Associative Containers </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0458r2.html">
P0458R2
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<entry> LWG 2511: guaranteed copy elision for piecewise construction </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0475r1.html">
P0475R1
</link>
</entry>
<entry align="center"> 7.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Bit-casting object representations </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0476r2.html">
P0476R2
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> The Curious Case of Padding Bits, Featuring Atomic Compare-and-Exchange </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0528r3.html">
P0528R3
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Support for contract based programming in C++ </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0542r5.html">
P0542R5
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> Integral power-of-2 operations </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0556r3.html">
P0556R3
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Reviewing Deprecated Facilities of C++17 for C++20 </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0619r4.html">
P0619R4
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> Improving the Return Value of Erase-Like Algorithms </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0646r1.pdf">
P0646R1
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry> <code>__cpp_lib_list_remove_return_type &gt;= 201806L</code> </entry>
</row>
<row>
<entry> Efficient sized delete for variable sized classes </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0722r3.html">
P0722R3
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry> <code>__cpp_lib_destroying_delete &gt;= 201806L</code> </entry>
</row>
<row>
<entry> Implicit conversion traits and utility functions </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0758r1.html">
P0758R1
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<entry> <code>fpos</code> Requirements </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0759r1.html">
P0759R1
</link>
</entry>
<entry align="center"> Note 1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Add <code>shift</code> to <code>&lt;algorithm&gt;</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0769r2.pdf">
P0769R2
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Standard Library Specification in a Concepts and Contracts World </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0788r3.pdf">
P0788R3
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Constexpr for <code>swap</code> and swap related functions </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0879r0.html">
P0879R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> The <code>identity</code> metafunction </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0887r1.pdf">
P0887R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> <code>explicit(bool)</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0892r2.html">
P0892R2
</link>
</entry>
<entry align="center"> Note 1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Standard Library Concepts </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0898r3.pdf">
P0898R3
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> Eradicating unnecessarily explicit default constructors from the standard library </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0935r0.html">
P0935R0
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<entry> Integrating feature-test macros into the C++ WD </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0941r2.html">
P0941R2
</link>
</entry>
<entry align="center"> 5.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> <code>constexpr</code> comparison operators for <code>std::array</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1023r0.pdf">
P1023R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Update The Reference To The Unicode Standard </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1025r1.html">
P1025R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Consistency improvements for <code>&lt;=&gt;</code> and other comparison operators </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1120r0.html">
P1120R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> <code>unwrap_ref_decay</code> and <code>unwrap_reference</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0318r1.pdf">
P0318R1
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Simplified partial function application </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0356r5.html">
P0356R5
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> <code>reference_wrapper</code> for incomplete types </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0357r3.html">
P0357R3
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> <code>char8_t</code>: A type for UTF-8 characters and strings </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0482r6.html">
P0482R6
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Fixing <code>operator&gt;&gt;(basic_istream&amp;, CharT*)</code> (LWG 2499) </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0487r1.html">
P0487R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Utility functions to implement uses-allocator construction </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0591r4.pdf">
P0591R4
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> P0595R2 <code>std::is_constant_evaluated()</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0595r2.html">
P0595R2
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<entry> <code>variant</code> and <code>optional</code> should propagate copy/move triviality </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0602r4.html">
P0602R4
</link>
</entry>
<entry align="center"> 8.3 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> A sane <code>variant</code> converting constructor </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0608r3.html">
P0608R3
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> <code>visit&lt;R&gt;</code>: Explicit Return Type for <code>visit</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0655r1.pdf">
P0655R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> <code>std::function</code> move constructor should be <code>noexcept</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0771r1.pdf">
P0771R1
</link>
</entry>
<entry align="center"> 7.2 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> The One Ranges Proposal </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0896r4.pdf">
P0896R4
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> P0899R1 - LWG 3016 is not a defect </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0899r1.html">
P0899R1
</link>
</entry>
<entry align="center"> 7.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Heterogeneous lookup for unordered containers </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0919r3.html">
P0919R3
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> <code>&lt;chrono&gt;</code> <code>zero()</code>, <code>min()</code>, and <code>max()</code> should be <code>noexcept</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0972r0.pdf">
P0972R0
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Constexpr in <code>std::pointer_traits</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1006r1.pdf">
P1006R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> <code>std::assume_aligned</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1007r3.pdf">
P1007R3
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Smart pointer creation with default initialization </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1020r1.html">
P1020R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Misc constexpr bits </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1032r1.html">
P1032R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Should Span be Regular? </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1085r2.md">
P1085R2
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Editorial Guidance for merging P0019r8 and P0528r3 </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1123r0.html">
P1123R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Cleaning up Clause 20 </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1148r0.pdf">
P1148R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Make stateful allocator propagation more consistent for <code>operator+(basic_string)</code> </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1165r1.html">
P1165R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<entry> Adopt Consistent Container Erasure from Library Fundamentals 2 for C++20 </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1209r0.html">
P1209R0
</link>
</entry>
<entry align="center"> 9.1 </entry>
<entry> <code>__cpp_lib_erase_if &gt;= 201811L</code> </entry>
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Completing the Rebase of Library Fundamentals, Version 3, Working Draft </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1210r0.html">
P1210R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Alternative Wording for P0907R4 Signed Integers are Two's Complement </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1236r1.html">
P1236R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Remove CommonReference requirement from StrictWeakOrdering (a.k.a Fixing Relations) </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1248r1.html">
P1248R1
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#C8B0B0" ?>
<entry> Improving Completeness Requirements for Type Traits </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1285r0.pdf">
P1285R0
</link>
</entry>
<entry align="center"> </entry>
<entry />
</row>
<row>
<?dbhtml bgcolor="#B0B0B0" ?>
<entry> Missing feature test macros </entry>
<entry>
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1353r0.html">
P1353R0
</link>
</entry>
<entry align="center"> Partial </entry>
<entry />
</row>
</tbody>
</tgroup>
</table>
<para>
Note 1: The changes in the proposal either do not affect the code in libstdc++,
or the changes are not required for conformance.
</para>
<section xml:id="iso.2020.specific" xreflabel="Implementation Specific"><info><title>Implementation Specific Behavior</title></info>
<para>For behaviour which is also specified by previous standards,
see <link linkend="iso.1998.specific">C++ 1998/2003 Implementation
Specific Behavior</link>, <link linkend="iso.2011.specific">C++
2011 Implementation Specific Behavior</link> and <link
linkend="iso.2017.specific">C++ 2017 Implementation Specific
Behavior</link>.
This section only documents behaviour which is new in the 202a draft.
</para>
</section>
</section>