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<h1>C++ Support in Clang</h1>
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<p>Last updated: $Date: 2018/07/17 18:31:55 $</p>
<p>Clang fully implements all published ISO C++ standards (<a
href="#cxx98">C++98 / C++03</a>, <a
href="#cxx11">C++11</a>, and <a
href="#cxx14">C++14</a>), and most of the upcoming <a
href="#cxx17">C++17</a> standard.
<p>The Clang community is continually striving to improve C++ standards
compliance between releases by submitting and tracking <a
href="cxx_dr_status.html">C++ Defect Reports</a> and implementing resolutions
as they become available.</p>
<p>Experimental work is also under way to implement <a href="#ts">C++ Technical
Specifications</a> that will help drive the future of the C++ programming
language.</p>
<p>The <a href="http://llvm.org/bugs/">LLVM bug tracker</a> contains Clang
C++ components that track known bugs with Clang's language conformance in
each language mode.</p>
<h2 id="cxx98">C++98 implementation status</h2>
<p>Clang implements all of the ISO C++ 1998 standard
(including the defects addressed in the ISO C++ 2003 standard)
except for <tt>export</tt> (which was removed in C++11).
<h2 id="cxx11">C++11 implementation status</h2>
<p>Clang 3.3 and later implement all of the <a
href="http://www.iso.org/standard/50372.html">ISO
C++ 2011 standard</a>.
<p>By default, Clang builds C++ code according to the C++98 standard, with many
C++11 features accepted as extensions. You can use Clang in C++11 mode with the
<code>-std=c++11</code> option. Clang's C++11 mode can be used
with <a href="http://libcxx.llvm.org/">libc++</a> or with gcc's libstdc++.
<details>
<summary>List of features and minimum Clang version with support</summary>
<table width="689" border="1" cellspacing="0">
<tr>
<th>Language Feature</th>
<th>C++11 Proposal</th>
<th>Available in Clang?</th>
</tr>
<tr>
<td>Rvalue references</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2118.html">N2118</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td> Rvalue references for <code>*this</code></td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2439.htm">N2439</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Initialization of class objects by rvalues</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1610.html">N1610</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Non-static data member initializers</td>
<td><a href="http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2008/n2756.htm">N2756</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>Variadic templates</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2242.pdf">N2242</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td> Extending variadic template template parameters</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2555.pdf">N2555</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Initializer lists</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2672.htm">N2672</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>Static assertions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1720.html">N1720</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td><code>auto</code>-typed variables</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1984.pdf">N1984</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td> Multi-declarator <code>auto</code></td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1737.pdf">N1737</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td> Removal of auto as a storage-class specifier</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2546.htm">N2546</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td> New function declarator syntax</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2541.htm">N2541</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td rowspan="2">Lambda expressions</td>
<td><a href="http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2009/n2927.pdf">N2927</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<!-- from Albuquerque 2017 -->
<td><a href="http://wg21.link/p0588r1">P0588R1</a> (<a href="#dr">DR</a>)</td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Declared type of an expression</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2343.pdf">N2343</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td> Incomplete return types</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3276.pdf">N3276</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>Right angle brackets</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1757.html">N1757</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Default template arguments for function templates</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#226">DR226</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Solving the SFINAE problem for expressions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2634.html">DR339</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Alias templates</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2258.pdf">N2258</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>Extern templates</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1987.htm">N1987</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Null pointer constant</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2431.pdf">N2431</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>Strongly-typed enums</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf">N2347</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Forward declarations for enums</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2764.pdf">N2764</a>
<br><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1206">DR1206</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>Standardized attribute syntax</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2761.pdf">N2761</a></td>
<td class="full" align="center">Clang 3.3 <a href="#n2761">(1)</a></td>
</tr>
<tr>
<td rowspan="2">Generalized constant expressions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2235.pdf">N2235</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<!-- from Albuquerque 2017 -->
<td><a href="http://wg21.link/p0859r0">P0859R0</a> (<a href="#dr">DR</a>)</td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Alignment support</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2341.pdf">N2341</a></td>
<td class="full" align="center">Clang 3.3</td>
</tr>
<tr>
<td>Conditionally-support behavior</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1627.pdf">N1627</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Changing undefined behavior into diagnosable errors</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1727.pdf">N1727</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Delegating constructors</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1986.pdf">N1986</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td rowspan="2">Inheriting constructors</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2540.htm">N2540</a></td>
<td class="full" align="center">Clang 3.3</td>
</tr>
<tr>
<!-- from Kona 2015 -->
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0136r1.html">P0136R1</a> (<a href="#dr">DR</a>)</td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td>Explicit conversion operators</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2437.pdf">N2437</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>New character types</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2249.html">N2249</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Unicode string literals</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2442.htm">N2442</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>Raw string literals</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2442.htm">N2442</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>Universal character names in literals</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2170.html">N2170</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>User-defined literals</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2765.pdf">N2765</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>Standard Layout Types</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2342.htm">N2342</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>Defaulted functions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2346.htm">N2346</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>Deleted functions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2346.htm">N2346</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Extended friend declarations</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1791.pdf">N1791</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Extending <code>sizeof</code></td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2253.html">N2253</a>
<br><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#850">DR850</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>Inline namespaces</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2535.htm">N2535</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Unrestricted unions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2544.pdf">N2544</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>Local and unnamed types as template arguments</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2657.htm">N2657</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td rowspan="2">Range-based for</td>
<td><a href="http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2009/n2930.html">N2930</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<!-- from Jacksonville 2018 -->
<td><a href="http://wg21.link/p0962r1">P0962R1</a> (<a href="#dr">DR</a>)</td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Explicit virtual overrides</td>
<td><a href="http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2009/n2928.htm">N2928</a>
<br><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3206.htm">N3206</a>
<br><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3272.htm">N3272</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>Minimal support for garbage collection and reachability-based leak detection</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2670.htm">N2670</a></td>
<td class="na" align="center">N/A <a href="#n2670">(2)</a></td>
</tr>
<tr>
<td>Allowing move constructors to throw [noexcept]</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3050.html">N3050</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr>
<td>Defining move special member functions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3053.html">N3053</a></td>
<td class="full" align="center">Clang 3.0</td>
</tr>
<tr class="separator">
<th align="center" colspan="3">Concurrency</th>
</tr>
<tr>
<td>Sequence points</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2239.html">N2239</a></td>
<td class="full" align="center">Clang 3.3</td>
</tr>
<tr>
<td>Atomic operations</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2427.html">N2427</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>Strong Compare and Exchange</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2748.html">N2748</a></td>
<td class="full" align="center">Clang 3.1 <a href="#n2748">(3)</a></td>
</tr>
<tr>
<td>Bidirectional Fences</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2752.htm">N2752</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>Memory model</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2429.htm">N2429</a></td>
<td class="full" align="center">Clang 3.2</td>
</tr>
<tr>
<td>Data-dependency ordering: atomics and memory model</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2664.htm">N2664</a></td>
<td class="full" align="center">Clang 3.2 <a href="#n2664">(4)</a></td>
</tr>
<tr>
<td>Propagating exceptions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2179.html">N2179</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Allow atomics use in signal handlers</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2547.htm">N2547</a></td>
<td class="full" align="center">Clang 3.1</td>
</tr>
<tr>
<td>Thread-local storage</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2659.htm">N2659</a></td>
<td class="full" align="center">Clang 3.3 <a href="#n2659">(5)</a></td>
</tr>
<tr>
<td>Dynamic initialization and destruction with concurrency</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2660.htm">N2660</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr class="separator">
<th align="center" colspan="3">C99 Features in C++11</th>
</tr>
<tr>
<td><code>__func__</code> predefined identifier</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2340.htm">N2340</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>C99 preprocessor</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1653.htm">N1653</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td><code>long long</code></td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1811.pdf">N1811</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>Extended integral types</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1988.pdf">N1988</a></td>
<td class="na" align="center">N/A <a href="#n1988">(6)</a></td>
</tr>
</table>
<p>
<span id="n2761">(1): The <code>[[carries_dependency]]</code> attribute
has no effect.</span><br>
<span id="n2670">(2): No compiler changes are required for an implementation
such as Clang that does not provide garbage collection.</span><br>
<span id="n2748">(3): All compare-exchange operations are emitted as
strong compare-exchanges.</span><br>
<span id="n2664">(4): <code>memory_order_consume</code> is lowered to
<code>memory_order_acquire</code>.</span><br>
<span id="n2659">(5): <code>thread_local</code> support
requires a C++ runtime library providing <code>__cxa_thread_atexit</code>, such
as <a href="http://libcxxabi.llvm.org">libc++abi</a> 3.6 or later,
or libsupc++ 4.8 or later.</span><br>
<span id="n1988">(6): No compiler changes are required for an implementation
such as Clang that does not provide any extended integer types.
<code>__int128</code> is not treated as an extended integer type,
because changing <code>intmax_t</code> would be an ABI-incompatible
change.</span>
</p>
</details>
<h2 id="cxx14">C++14 implementation status</h2>
<p>Clang 3.4 and later implement all of the <a
href="http://www.iso.org/standard/64029.html">ISO
C++ 2014 standard</a>.
<p>You can use Clang in C++14 mode with the <code>-std=c++14</code> option
(use <code>-std=c++1y</code> in Clang 3.4 and earlier).</p>
<details>
<summary>List of features and minimum Clang version with support</summary>
<table width="689" border="1" cellspacing="0">
<tr>
<th>Language Feature</th>
<th>C++14 Proposal</th>
<th>Available in Clang?</th>
</tr>
<tr>
<td>Tweak to certain C++ contextual conversions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3323.pdf">N3323</a></td>
<td class="full" align="center">Clang 3.4</td>
</tr>
<tr>
<td>Binary literals</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3472.pdf">N3472</a></td>
<td class="full" align="center">Clang 2.9</td>
</tr>
<tr>
<td>decltype(auto)</td>
<td rowspan=2 style="vertical-align:middle"><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3638.html">N3638</a></td>
<td class="full" align="center">Clang 3.3</td>
</tr>
<tr>
<td>Return type deduction for normal functions</td>
<td class="full" align="center">Clang 3.4</td>
</tr>
<tr>
<td>Initialized lambda captures</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3648.html">N3648</a></td>
<td class="full" align="center">Clang 3.4</td>
</tr>
<tr>
<td>Generic lambdas</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3649.html">N3649</a></td>
<td class="full" align="center">Clang 3.4</td>
</tr>
<tr>
<td>Variable templates</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3651.pdf">N3651</a></td>
<td class="full" align="center">Clang 3.4</td>
</tr>
<tr>
<td>Relaxing requirements on constexpr functions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3652.html">N3652</a></td>
<td class="full" align="center">Clang 3.4</td>
</tr>
<tr>
<td>Member initializers and aggregates</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3653.html">N3653</a></td>
<td class="full" align="center">Clang 3.3</td>
</tr>
<tr>
<td>Clarifying memory allocation</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3664.html">N3664</a></td>
<td class="full" align="center">Clang 3.4</td>
</tr>
<tr>
<td><tt>[[deprecated]]</tt> attribute</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3760.html">N3760</a></td>
<td class="full" align="center">Clang 3.4</td>
</tr>
<tr>
<td>Single quotation mark as digit separator</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3781.pdf">N3781</a></td>
<td class="full" align="center">Clang 3.4</td>
</tr>
<tr>
<td>C++ Sized Deallocation</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3778.html">N3778</a></td>
<td class="full" align="center">Clang 3.4 <a href="#n3778">(7)</a></td>
</tr>
</table>
<p>
<span id="n3778">(7): In Clang 3.7 and later, sized deallocation is only enabled
if the user passes the <code>-fsized-deallocation</code> flag. The user must
supply definitions of the sized deallocation functions, either by providing them
explicitly or by using a C++ standard library that does. <code>libstdc++</code>
added these functions in version 5.0, and <code>libc++</code> added them in
version 3.7.
</span>
</p>
</details>
<h2 id="cxx17">C++17 implementation status</h2>
<p>Clang 5 and later implement all the features of the
<a href="https://www.iso.org/standard/68564.html">ISO C++ 2017 standard</a>.
<p>You can use Clang in C++17 mode with the <code>-std=c++17</code> option
(use <code>-std=c++1z</code> in Clang 4 and earlier).</p>
<details open>
<summary>List of features and minimum Clang version with support</summary>
<table width="689" border="1" cellspacing="0">
<tr>
<th>Language Feature</th>
<th>C++17 Proposal</th>
<th>Available in Clang?</th>
</tr>
<!-- Issaquah 2014 papers -->
<tr>
<td><tt>static_assert</tt> with no message</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n3928.pdf">N3928</a></td>
<td class="full" align="center">Clang 3.5</td>
</tr>
<!-- Rapperswil papers -->
<tr>
<td>Disabling trigraph expansion by default</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4086.html">N4086</a></td>
<td class="full" align="center">Clang 3.5</td>
</tr>
<!--
<tr>
<td rowspan="2">Terse range-based for loops (removed from C++17)</td>
<td rowspan="2"><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n3994.htm">N3994</a></td>
<td class="none" align="center">Clang 3.5: Yes</td>
</tr>
<tr>
<td class="svn" align="center">SVN: No</td>
</tr>
-->
<tr>
<td><tt>typename</tt> in a template template parameter</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4051.html">N4051</a></td>
<td class="full" align="center">Clang 3.5</td>
</tr>
<tr>
<td>New <tt>auto</tt> rules for direct-list-initialization
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n3922.html">N3922</a></td>
<td class="full" align="center">Clang 3.8 <a href="#n3922">(8)</a></td>
</tr>
<!-- Urbana papers -->
<tr>
<td rowspan="2">Fold expressions</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4295.html">N4295</a></td>
<td class="full" align="center">Clang 3.6</td>
</tr>
<tr> <!-- from Jacksonville -->
<td><a href="http://wg21.link/p0036r0">P0036R0</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td><tt>u8</tt> character literals</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4267.html">N4267</a></td>
<td class="full" align="center">Clang 3.6</td>
</tr>
<tr>
<td>Nested namespace definition</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4230.html">N4230</a></td>
<td class="full" align="center">Clang 3.6</td>
</tr>
<tr>
<td>Attributes for namespaces and enumerators</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4266.html">N4266</a></td>
<td class="full" align="center">Clang 3.6</td>
</tr>
<tr>
<td>Allow constant evaluation for all non-type template arguments</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4268.html">N4268</a></td>
<td class="full" align="center">Clang 3.6</td>
</tr>
<!-- Kona papers -->
<tr>
<td>Remove deprecated <tt>register</tt> storage class</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0001r1.html">P0001R1</a></td>
<td class="full" align="center">Clang 3.8</td>
</tr>
<tr>
<td>Remove deprecated <tt>bool</tt> increment</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0002r1.html">P0002R1</a></td>
<td class="full" align="center">Clang 3.8</td>
</tr>
<tr>
<td>Make exception specifications part of the type system</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0012r1.html">P0012R1</a></td>
<td class="full" align="center">Clang 4</td>
</tr>
<tr>
<td><tt>__has_include</tt> in preprocessor conditionals</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0061.html">P0061R1</a></td>
<td class="full" align="center">Yes</td>
</tr>
<!-- Jacksonville papers -->
<tr>
<td><tt>[[fallthrough]]</tt> attribute</td>
<td><a href="http://wg21.link/p0188r1">P0188R1</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td><tt>[[nodiscard]]</tt> attribute</td>
<td><a href="http://wg21.link/p0189r1">P0189R1</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td><tt>[[maybe_unused]]</tt> attribute</td>
<td><a href="http://wg21.link/p0212r1">P0212R1</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td>Aggregate initialization of classes with base classes</td>
<td><a href="http://wg21.link/p0017r1">P0017R1</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td><tt>constexpr</tt> lambda expressions</td>
<td><a href="http://wg21.link/p0170r1">P0170R1</a></td>
<td class="full" align="center">Clang 5</td>
</tr>
<tr>
<td>Differing <tt>begin</tt> and <tt>end</tt> types in range-based <tt>for</tt></td>
<td><a href="http://wg21.link/p0184r0">P0184R0</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td>Lambda capture of <tt>*this</tt></td>
<td><a href="http://wg21.link/p0018r3">P0018R3</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td>Direct-list-initialization of <tt>enum</tt>s</td>
<td><a href="http://wg21.link/p0138r2">P0138R2</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td>Hexadecimal floating-point literals</td>
<td><a href="http://wg21.link/p0245r1">P0245R1</a></td>
<td class="full" align="center">Yes</td>
</tr>
<!-- Oulu papers -->
<tr>
<td>Using attribute namespaces without repetition</td>
<td><a href="http://wg21.link/p0028r4">P0028R4</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td>Dynamic memory allocation for over-aligned data</td>
<td><a href="http://wg21.link/p0035r4">P0035R4</a></td>
<td class="full" align="center">Clang 4</td>
</tr>
<tr>
<td rowspan="4">Template argument deduction for class templates</td>
<td><a href="http://wg21.link/p0091r3">P0091R3</a></td>
<td rowspan="2" class="full" align="center">Clang 5</td>
</tr>
<tr> <!-- from Issaquah -->
<td><a href="http://wg21.link/p0512r0">P0512R0</a></td>
</tr>
<tr>
<!-- from Kona 2017 -->
<td><a href="http://wg21.link/p0620r1">P0620R0</a> (<a href="#dr">DR</a>)</td>
<td class="svn" align="center">SVN</td>
</tr>
<tr>
<!-- from Toronto 2017 -->
<td><a href="http://wg21.link/p0702r1">P0702R1</a> (<a href="#dr">DR</a>)</td>
<td class="full" align="center">Clang 6</td>
</tr>
<tr>
<td>Non-type template parameters with <tt>auto</tt> type</td>
<td><a href="http://wg21.link/p0127r2">P0127R2</a></td>
<td class="full" align="center">Clang 4</td>
</tr>
<tr>
<td>Guaranteed copy elision</td>
<td><a href="http://wg21.link/p0135r1">P0135R1</a></td>
<td class="full" align="center">Clang 4</td>
</tr>
<tr>
<td rowspan=2>Stricter expression evaluation order</td>
<td><a href="http://wg21.link/p0145r3">P0145R3</a></td>
<td class="full" align="center" rowspan=2>Clang 4 <a href="#p0145">(9)</a></td>
</tr>
<tr>
<td><a href="http://wg21.link/p0400r0">P0400R0</a></td>
</tr>
<tr>
<td>Requirement to ignore unknown attributes</td>
<td><a href="http://wg21.link/p0283r2">P0283R2</a></td>
<td class="full" align="center">Yes</td>
</tr>
<tr>
<td><tt>constexpr</tt> <em>if-statement</em>s</td>
<td><a href="http://wg21.link/p0292r2">P0292R2</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td>Inline variables</td>
<td><a href="http://wg21.link/p0386r2">P0386R2</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<tr>
<td rowspan="3">Structured bindings</td>
<td><a href="http://wg21.link/p0217r3">P0217R3</a></td>
<td class="full" align="center">Clang 4</td>
</tr>
<tr>
<!-- from Jacksonville 2018 -->
<td><a href="http://wg21.link/p0961r1">P0961R1</a> (<a href="#dr">DR</a>)</td>
<td class="none" align="center">No</td>
</tr>
<tr>
<!-- from Jacksonville 2018 -->
<td><a href="http://wg21.link/p0969r0">P0969R0</a> (<a href="#dr">DR</a>)</td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Separate variable and condition for <tt>if</tt> and <tt>switch</tt></td>
<td><a href="http://wg21.link/p0305r1">P0305R1</a></td>
<td class="full" align="center">Clang 3.9</td>
</tr>
<!-- Issaquah 2016 papers -->
<tr>
<td>Matching template template parameters to compatible arguments</td>
<td><a href="http://wg21.link/p0522r0">P0522R0</a></td>
<td class="partial" align="center">Partial <a href="#p0522">(10)</a></td>
</tr>
<tr>
<td>Removing deprecated dynamic exception specifications</td>
<td><a href="http://wg21.link/p0003r5">P0003R5</a></td>
<td class="full" align="center">Clang 4</td>
</tr>
<tr>
<td>Pack expansions in <em>using-declarations</em></td>
<td><a href="http://wg21.link/p0195r2">P0195R2</a></td>
<td class="full" align="center">Clang 4</td>
</tr>
</table>
<p>
<span id="n3922">(8): This is a backwards-incompatible change that is applied to
all language versions that allow type deduction from <tt>auto</tt>
(per the request of the C++ committee).
In Clang 3.7, a warning is emitted for all cases that would change meaning.
</span><br>
<span id="p0145">(9): Under the MS ABI, function parameters are destroyed from
left to right in the callee. As a result, function parameters in calls to
<tt>operator<<</tt>, <tt>operator>></tt>, <tt>operator->*</tt>,
<tt>operator&&</tt>, <tt>operator||</tt>, and <tt>operator,</tt>
functions using expression syntax are no longer guaranteed to be destroyed in
reverse construction order in that ABI.
</span><br>
<span id="p0522">(10): Despite being the resolution to a Defect Report, this
feature is disabled by default in all language versions, and can be enabled
explicitly with the flag <tt>-frelaxed-template-template-args</tt> in Clang 4
onwards.
The change to the standard lacks a corresponding change for template partial
ordering, resulting in ambiguity errors for reasonable and previously-valid
code. This issue is expected to be rectified soon.
</span>
</p>
</details>
<h2 id="cxx20">C++2a implementation status</h2>
<p>Clang has <b>experimental</b> support for some proposed features of
the C++ standard following C++17, provisionally named C++2a.
Note that support for these features may change or be removed without notice,
as the draft C++2a standard evolves.
<p>You can use Clang in C++2a mode with the <code>-std=c++2a</code> option.</p>
<details open>
<summary>List of features and minimum Clang version with support</summary>
<table width="689" border="1" cellspacing="0">
<tr>
<th>Language Feature</th>
<th>C++2a Proposal</th>
<th>Available in Clang?</th>
</tr>
<!-- Toronto 2017 papers -->
<tr>
<td>Default member initializers for bit-fields</td>
<td><a href="http://wg21.link/p0683r1">P0683R1</a></td>
<td class="full" align="center">Clang 6</td>
</tr>
<tr>
<td><tt>const&</tt>-qualified pointers to members</td>
<td><a href="http://wg21.link/p0704r1">P0704R1</a></td>
<td class="full" align="center">Clang 6</td>
</tr>
<tr>
<td>Allow <i>lambda-capture</i> <tt>[=, this]</tt></td>
<td><a href="http://wg21.link/p0409r2">P0409R2</a></td>
<td class="full" align="center">Clang 6</td>
</tr>
<tr>
<td rowspan="2"><tt>__VA_OPT__</tt> for preprocessor comma elision</td>
<td><a href="http://wg21.link/p0306r4">P0306R4</a></td>
<td class="full" align="center">Clang 6</td>
</tr>
<tr> <!-- from Rapperswil -->
<td><a href="http://wg21.link/p1042r1">P1042R1</a></td>
<td class="partial" align="center">Partial</td>
</tr>
<tr>
<td>Designated initializers</td>
<td><a href="http://wg21.link/p0329r4">P0329R4</a></td>
<td class="partial" align="center">Partial (extension)</td>
</tr>
<tr>
<td><i>template-parameter-list</i> for generic lambdas</td>
<td><a href="http://wg21.link/p0428r2">P0428R2</a></td>
<td class="none" align="center">No</td>
</tr>
<tr id="p0734">
<td rowspan="2">Concepts</td>
<td><a href="http://wg21.link/p0734r0">P0734R0</a></td>
<td rowspan="2" class="none" align="center">No</td>
</tr>
<tr> <!-- from Albuquerque -->
<td><a href="http://wg21.link/p0857r0">P0857R0</a></td>
</tr>
<!-- Albuquerque papers -->
<tr>
<td>Range-based for statements with initializer</td>
<td><a href="http://wg21.link/p0614r1">P0614R1</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>ADL and function templates that are not visible</td>
<td><a href="http://wg21.link/p0846r0">P0846R0</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td><tt>const</tt> mismatch with defaulted copy constructor</td>
<td><a href="http://wg21.link/p0641r2">P0641R2</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td rowspan="3">Consistent comparison (<tt>operator<=></tt>)</td>
<td><a href="http://wg21.link/p0515r3">P0515R3</a></td>
<td rowspan="3" class="partial" align="center">Partial</td>
</tr>
<tr> <!-- from Jacksonville -->
<td><a href="http://wg21.link/p0905r1">P0905R1</a></td>
</tr>
<tr> <!-- from Rapperswil -->
<td><a href="http://wg21.link/p1120r0">P1120R0</a></td>
</tr>
<tr>
<td>Access checking on specializations</td>
<td><a href="http://wg21.link/p0692r1">P0692R1</a></td>
<td class="partial" align="center">Partial</td>
</tr>
<tr>
<td>Default constructible and assignable stateless lambdas</td>
<td><a href="http://wg21.link/p0624r2">P0624R2</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Lambdas in unevaluated contexts</td>
<td><a href="http://wg21.link/p0315r4">P0315R4</a></td>
<td class="none" align="center">No</td>
</tr>
<!-- Jacksonville papers -->
<tr>
<td><tt>[[no_unique_address]]</tt> attribute</td>
<td><a href="http://wg21.link/p0840r2">P0840R2</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td><tt>[[likely]]</tt> and <tt>[[unlikely]]</tt> attributes</td>
<td><a href="http://wg21.link/p0479r5">P0479R5</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td><tt>typename</tt> optional in more contexts</td>
<td><a href="http://wg21.link/p0634r3">P0634R3</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Pack expansion in lambda <i>init-capture</i></td>
<td><a href="http://wg21.link/p0780r2">P0780R2</a></td>
<td class="none" align="center">No</td>
</tr>
<!-- Rapperswil papers -->
<tr>
<td>Class types as non-type template parameters</td>
<td><a href="http://wg21.link/p0732r2">P0732R2</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Destroying operator delete</td>
<td><a href="http://wg21.link/p0722r3">P0722R3</a></td>
<td class="full" align="center">Clang 6</td>
</tr>
<tr>
<td>Virtual function calls in constant expressions</td>
<td><a href="http://wg21.link/p1064r0">P1064R0</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Prohibit aggregates with user-declared constructors</td>
<td><a href="http://wg21.link/p1008r1">P1008R1</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Contracts</td>
<td><a href="http://wg21.link/p0542r5">P0542R5</a></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>Feature test macros</td>
<td><a href="http://wg21.link/p0941r2">P0941R2</a></td>
<td class="full" align="center"><a href="#sd6">(see below)</a></td>
</tr>
<tr>
<td><tt>explicit(bool)</tt></td>
<td><a href="http://wg21.link/p0892r2">P0892R2</a></td>
<td class="none" align="center">No</td>
</tr>
</table>
</details>
<h2 id="dr">Defect reports</h2>
<p>Clang generally aims to implement resolutions to Defect Reports (bug fixes
against prior standards) retroactively, in all prior standard versions where
the fix is meaningful. Significant Defect Report changes to language features
after the publication of the relevant standard are marked (DR) in the above
table.</p>
<p>Clang also has a test suite for conformance to resolutions for issues on the
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_toc.html">C++ core issues list</a>,
most of which are considered Defect Reports.
<a href="cxx_dr_status.html">Implementation status for C++ core issues</a> based on
that test suite is tracked on a separate page.</p>
<h2 id="ts">Technical specifications and standing documents</h2>
<p>ISO C++ also publishes a number of documents describing additional language
and library features that are not part of standard C++.</p>
<details open>
<summary>List of features and minimum Clang version with support</summary>
<table width="689" border="1" cellspacing="0">
<tr>
<th>Document</th>
<th>Latest draft</th>
<th>Compiler flag</th>
<th>Available in Clang?</th>
</tr>
<tr id="sd6">
<td rowspan="5">SD-6: SG10 feature test recommendations</td>
<td rowspan="5"><a href="http://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations">SD-6</a></td>
<td rowspan="5">N/A</td>
<td class="full" align="center">
Clang 3.4 (<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3745">N3745</a>)</br>
</td>
</tr>
<tr>
<td class="full" align="center">
Clang 3.6 (<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4200">N4200</a>)</a>
</td>
</tr>
<tr>
<td class="full" align="center">
Clang 4 (<a href="http://wg21.link/p0096r3">P0096R3</a>)</a>
</td>
</tr>
<tr>
<td class="full" align="center">
Clang 5 (<a href="http://wg21.link/p0096r4">P0096R4</a>)</a>
</td>
</tr>
<tr>
<td class="svn" align="center">
SVN (<a href="http://wg21.link/p0096r5">P0096R5</a>)</a>
</td>
</tr>
<!-- FIXME: Implement latest recommendations.
<tr>
<td class="svn" align="center">
SVN (<a href="http://wg21.link/p0096r3">P0096R3</a>)</a>
</td>
</tr>
-->
<!-- No compiler support is known to be needed for:
* Concurrency TS
* Parallelism TS (v1, v2)
* Ranges TS
* Networking TS
* File System TS
-->
<tr>
<td>[TS] Concepts</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0121r0.pdf">P0121R0</a></td>
<td></td>
<td class="na" align="center">Superseded by <a href="#p0734">P0734R0</a></td>
</tr>
<tr>
<!-- track unimplemented Coroutines features: p0913r1 p0914r1 -->
<td>[DRAFT TS] Coroutines</td>
<td><a href="https://isocpp.org/files/papers/N4663.pdf">N4663</a></td>
<td><tt>-fcoroutines-ts<br>-stdlib=libc++</tt></td>
<td class="full" align="center">Clang 5</td>
</tr>
<tr>
<td>[TS] Library Fundamentals, Version 1 (invocation type traits)</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4480.html">N4480</a></td>
<td>N/A</td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>[TS] Library Fundamentals, Version 2 (<tt>source_location</tt>)</td>
<td><a href="http://wg21.link/n4617">N4617</a></td>
<td>N/A</td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>[TS] Modules</td>
<td><a href="http://wg21.link/n4720">N4720</a></td>
<td><tt>-fmodules-ts</tt></td>
<td class="none" align="center">WIP</td>
</tr>
<tr>
<td>[DRAFT TS] Reflection</td>
<td><a href="http://wg21.link/n4746">N4746</a></td>
<td></td>
<td class="none" align="center">No</td>
</tr>
<tr>
<td>[TS] Transactional Memory</td>
<td><a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4514.pdf">N4514</a></td>
<td></td>
<td class="none" align="center">No</td>
</tr>
</table>
</details>
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