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15 <a href="http://llvm.org/">LLVM Home</a>
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Howard Hinnant2807d4a2010-08-22 01:04:38 +0000[diff] [blame]17
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]18 <div class="submenu">
19 <label>libc++ Info</label>
20 <a href="/index.html">About</a>
21 </div>
22
23 <div class="submenu">
24 <label>Quick Links</label>
Tanya Lattner29f6af32015-08-05 03:59:14 +0000[diff] [blame]25 <a href="http://lists.llvm.org/mailman/listinfo/cfe-dev">cfe-dev</a>
26 <a href="http://lists.llvm.org/mailman/listinfo/cfe-commits">cfe-commits</a>
Eric Fiselier3c354912017-02-17 08:37:03 +0000[diff] [blame]27 <a href="https://bugs.llvm.org/">Bug Reports</a>
Howard Hinnant38a59272010-05-11 20:51:20 +0000[diff] [blame]28 <a href="http://llvm.org/svn/llvm-project/libcxx/trunk/">Browse SVN</a>
29 <a href="http://llvm.org/viewvc/llvm-project/libcxx/trunk/">Browse ViewVC</a>
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]30 </div>
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33<div id="content">
34 <!--*********************************************************************-->
35 <h1>"libc++" C++ Standard Library</h1>
36 <!--*********************************************************************-->
Howard Hinnant2807d4a2010-08-22 01:04:38 +0000[diff] [blame]37
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]38 <p>libc++ is a new implementation of the C++ standard library, targeting
Howard Hinnant51eb2ad2012-07-19 15:57:51 +0000[diff] [blame]39 C++11.</p>
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]40
Chris Lattner58dffe62010-11-16 21:40:19 +0000[diff] [blame]41 <p>All of the code in libc++ is <a
42 href="http://llvm.org/docs/DeveloperPolicy.html#license">dual licensed</a>
43 under the MIT license and the UIUC License (a BSD-like license).</p>
Howard Hinnant2807d4a2010-08-22 01:04:38 +0000[diff] [blame]44
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]45 <!--=====================================================================-->
Eric Fiselier9da4c8e2015-10-14 20:51:33 +0000[diff] [blame]46 <h2>New Documentation Coming Soon!</h2>
47 <!--=====================================================================-->
48
49 <p> Looking for documentation on how to use, build and test libc++? If so
50 checkout the new libc++ documentation.</p>
51
52 <p><a href="http://libcxx.llvm.org/docs/">
53 Click here for the new libc++ documentation.</a></p>
54
55 <!--=====================================================================-->
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]56 <h2 id="goals">Features and Goals</h2>
57 <!--=====================================================================-->
Howard Hinnant2807d4a2010-08-22 01:04:38 +0000[diff] [blame]58
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]59 <ul>
Howard Hinnant51eb2ad2012-07-19 15:57:51 +0000[diff] [blame]60 <li>Correctness as defined by the C++11 standard.</li>
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]61 <li>Fast execution.</li>
62 <li>Minimal memory use.</li>
63 <li>Fast compile times.</li>
64 <li>ABI compatibility with gcc's libstdc++ for some low-level features
65 such as exception objects, rtti and memory allocation.</li>
66 <li>Extensive unit tests.</li>
67 </ul>
68
69 <!--=====================================================================-->
Marshall Clow497d9d22012-11-14 16:31:15 +0000[diff] [blame]70 <h2 id="why">Why a new C++ Standard Library for C++11?</h2>
Chris Lattner27de3d62010-05-12 22:21:15 +0000[diff] [blame]71 <!--=====================================================================-->
Howard Hinnant2807d4a2010-08-22 01:04:38 +0000[diff] [blame]72
Chris Lattner27de3d62010-05-12 22:21:15 +0000[diff] [blame]73 <p>After its initial introduction, many people have asked "why start a new
74 library instead of contributing to an existing library?" (like Apache's
75 libstdcxx, GNU's libstdc++, STLport, etc). There are many contributing
76 reasons, but some of the major ones are:</p>
Howard Hinnant2807d4a2010-08-22 01:04:38 +0000[diff] [blame]77
Chris Lattner27de3d62010-05-12 22:21:15 +0000[diff] [blame]78 <ul>
79 <li><p>From years of experience (including having implemented the standard
80 library before), we've learned many things about implementing
81 the standard containers which require ABI breakage and fundamental changes
82 to how they are implemented. For example, it is generally accepted that
83 building std::string using the "short string optimization" instead of
84 using Copy On Write (COW) is a superior approach for multicore
Marshall Clow497d9d22012-11-14 16:31:15 +0000[diff] [blame]85 machines (particularly in C++11, which has rvalue references). Breaking
Chris Lattnerf005e8d2010-05-12 22:30:22 +0000[diff] [blame]86 ABI compatibility with old versions of the library was
Chris Lattner27de3d62010-05-12 22:21:15 +0000[diff] [blame]87 determined to be critical to achieving the performance goals of
88 libc++.</p></li>
Howard Hinnant2807d4a2010-08-22 01:04:38 +0000[diff] [blame]89
Chris Lattner27de3d62010-05-12 22:21:15 +0000[diff] [blame]90 <li><p>Mainline libstdc++ has switched to GPL3, a license which the developers
91 of libc++ cannot use. libstdc++ 4.2 (the last GPL2 version) could be
Marshall Clow497d9d22012-11-14 16:31:15 +0000[diff] [blame]92 independently extended to support C++11, but this would be a fork of the
Chris Lattnera940b5b2010-05-12 22:33:00 +0000[diff] [blame]93 codebase (which is often seen as worse for a project than starting a new
94 independent one). Another problem with libstdc++ is that it is tightly
95 integrated with G++ development, tending to be tied fairly closely to the
96 matching version of G++.</p>
Chris Lattner27de3d62010-05-12 22:21:15 +0000[diff] [blame]97 </li>
98
99 <li><p>STLport and the Apache libstdcxx library are two other popular
Marshall Clow497d9d22012-11-14 16:31:15 +0000[diff] [blame]100 candidates, but both lack C++11 support. Our experience (and the
Howard Hinnant51eb2ad2012-07-19 15:57:51 +0000[diff] [blame]101 experience of libstdc++ developers) is that adding support for C++11 (in
Chris Lattner27de3d62010-05-12 22:21:15 +0000[diff] [blame]102 particular rvalue references and move-only types) requires changes to
103 almost every class and function, essentially amounting to a rewrite.
Chris Lattnerd55fd112010-05-12 22:34:21 +0000[diff] [blame]104 Faced with a rewrite, we decided to start from scratch and evaluate every
105 design decision from first principles based on experience.</p>
Howard Hinnant2807d4a2010-08-22 01:04:38 +0000[diff] [blame]106
Chris Lattner27de3d62010-05-12 22:21:15 +0000[diff] [blame]107 <p>Further, both projects are apparently abandoned: STLport 5.2.1 was
108 released in Oct'08, and STDCXX 4.2.1 in May'08.</p>
109
110 </ul>
111
112 <!--=====================================================================-->
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]113 <h2 id="requirements">Platform Support</h2>
114 <!--=====================================================================-->
115
Dan Albertec4de782014-08-11 15:12:46 +0000[diff] [blame]116 <p>
117 libc++ is known to work on the following platforms, using g++-4.2 and
118 clang (lack of C++11 language support disables some functionality). Note
119 that functionality provided by &lt;atomic&gt; is only functional with
120 clang.
121 </p>
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]122
Dan Albertec4de782014-08-11 15:12:46 +0000[diff] [blame]123 <ul>
124 <li>Mac OS X i386</li>
125 <li>Mac OS X x86_64</li>
126 <li>FreeBSD 10+ i386</li>
127 <li>FreeBSD 10+ x86_64</li>
128 <li>FreeBSD 10+ ARM</li>
129 </ul>
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]130
131 <!--=====================================================================-->
132 <h2 id="dir-structure">Current Status</h2>
133 <!--=====================================================================-->
134
Howard Hinnant6852b552012-11-27 18:52:32 +0000[diff] [blame]135 <p>libc++ is a 100% complete C++11 implementation on Apple's OS X. </p>
Michael J. Spencerbb8cfd02012-12-31 19:34:21 +0000[diff] [blame]136 <p>LLVM and Clang can self host in C++ and C++11 mode with libc++ on Linux.</p>
Dan Albert2477bed2015-01-30 22:33:41 +0000[diff] [blame]137 <p>libc++ is also a 100% complete C++14 implementation. A list of new features and changes for
Marshall Clowca6e3662014-04-03 02:35:29 +0000[diff] [blame]138 C++14 can be found <a href="cxx1y_status.html">here</a>.</p>
Marshall Clow68640682014-11-10 15:43:20 +0000[diff] [blame]139 <p>A list of features and changes for the next C++ standard, known here as
140 "C++1z" (probably to be C++17) can be found <a href="cxx1z_status.html">here</a>.</p>
Marshall Clowf39d9142014-06-02 23:37:13 +0000[diff] [blame]141 <p>Implementation of the post-c++14 Technical Specifications is in progress. A list of features and
142 the current status of these features can be found <a href="ts1z_status.html">here</a>.</p>
Howard Hinnantd7aac282011-09-28 15:44:39 +0000[diff] [blame]143
Eric Fiseliercd6ac3a2014-08-18 05:25:04 +0000[diff] [blame]144 <!--======================================================================-->
Dan Albert2477bed2015-01-30 22:33:41 +0000[diff] [blame]145 <h2 id="buildbots">Build Bots</h2>
Eric Fiseliercd6ac3a2014-08-18 05:25:04 +0000[diff] [blame]146 <!--======================================================================-->
Eric Fiselierf60e4412014-12-09 22:53:21 +0000[diff] [blame]147 <p>The latest libc++ build results can be found at the following locations.</p>
Eric Fiseliercd6ac3a2014-08-18 05:25:04 +0000[diff] [blame]148 <ul>
Eric Fiselierf60e4412014-12-09 22:53:21 +0000[diff] [blame]149 <li><a href="http://lab.llvm.org:8011/console">
150 Buildbot libc++ builders
Eric Fiseliercd6ac3a2014-08-18 05:25:04 +0000[diff] [blame]151 </a></li>
Eric Fiselierf60e4412014-12-09 22:53:21 +0000[diff] [blame]152 <li><a href="http://lab.llvm.org:8080/green/view/Libcxx/">
153 Jenkins libc++ builders
Eric Fiselier8c5bc1c2014-10-16 02:48:59 +0000[diff] [blame]154 </a></li>
Eric Fiseliercd6ac3a2014-08-18 05:25:04 +0000[diff] [blame]155 </ul>
156
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]157 <!--=====================================================================-->
158 <h2>Get it and get involved!</h2>
159 <!--=====================================================================-->
Howard Hinnant2807d4a2010-08-22 01:04:38 +0000[diff] [blame]160
Howard Hinnant4f4d3102011-09-30 16:58:02 +0000[diff] [blame]161 <p>First please review our
162 <a href="http://llvm.org/docs/DeveloperPolicy.html">Developer's Policy</a>.
163
Eric Fiseliere44604a2016-06-02 02:16:28 +0000[diff] [blame]164 The documentation for building and using libc++ can be found below.
165 <ul>
166 <li><a href="http://libcxx.llvm.org/docs/UsingLibcxx.html">
167 <b>Using libc++</b></a>
168 Documentation on using the library in your programs</li>
169 <li><a href="http://libcxx.llvm.org/docs/BuildingLibcxx.html">
170 <b>Building libc++</b></a>
171 Documentation on building the library using CMake</li>
172 <li><a href="http://libcxx.llvm.org/docs/TestingLibcxx.html">
173 <b>Testing libc++</b></a>
174 Documentation for developers wishing to test the library</li>
175 </ul>
Dan Albertec4de782014-08-11 15:12:46 +0000[diff] [blame]176
177 <!--=====================================================================-->
Eric Fiselier9243c762015-05-12 22:55:30 +0000[diff] [blame]178 <h3>Notes and Known Issues</h3>
Dan Albertec4de782014-08-11 15:12:46 +0000[diff] [blame]179 <!--=====================================================================-->
180
181 <p>
Eric Fiselier9243c762015-05-12 22:55:30 +0000[diff] [blame]182 <ul>
183 <li>
184 Building libc++ with <code>-fno-rtti</code> is not supported. However
185 linking against it with <code>-fno-rtti</code> is supported.
186 </li>
187 <li>
188 On OS X v10.8 and older the CMake option
189 <code>-DLIBCXX_LIBCPPABI_VERSION=""</code> must be used during
190 configuration.
191 </li>
192 </ul>
Dan Albertec4de782014-08-11 15:12:46 +0000[diff] [blame]193 </p>
194
195 <p>Send discussions to the
Tanya Lattner29f6af32015-08-05 03:59:14 +0000[diff] [blame]196 <a href="http://lists.llvm.org/mailman/listinfo/cfe-dev">clang mailing list</a>.</p>
Dan Albertec4de782014-08-11 15:12:46 +0000[diff] [blame]197
198 <!--=====================================================================-->
Marshall Clow17c6aa02014-04-03 03:13:12 +0000[diff] [blame]199 <h2>Bug reports and patches</h2>
200 <!--=====================================================================-->
201
Dan Albert2477bed2015-01-30 22:33:41 +0000[diff] [blame]202 <p>
203 If you think you've found a bug in libc++, please report it using
204 the <a href="http://llvm.org/bugs">LLVM Bugzilla</a>. If you're not sure, you
Tanya Lattner29f6af32015-08-05 03:59:14 +0000[diff] [blame]205 can post a message to the <a href="http://lists.llvm.org/mailman/listinfo/cfe-dev">cfe-dev</a>
Dan Albert2477bed2015-01-30 22:33:41 +0000[diff] [blame]206 mailing list or on IRC. Please include "libc++" in your subject.
207 </p>
Marshall Clow17c6aa02014-04-03 03:13:12 +0000[diff] [blame]208
Dan Albert2477bed2015-01-30 22:33:41 +0000[diff] [blame]209 <p>
210 If you want to contribute a patch to libc++, the best place for that is
211 <a href="http://llvm.org/docs/Phabricator.html">Phabricator</a>. Please
212 include [libc++] in the subject and add cfe-commits as a subscriber.
213 </p>
Marshall Clow17c6aa02014-04-03 03:13:12 +0000[diff] [blame]214
215 <!--=====================================================================-->
Howard Hinnant1de22662010-10-05 16:44:40 +0000[diff] [blame]216 <h2>Design Documents</h2>
217 <!--=====================================================================-->
218
219<ul>
220<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
Howard Hinnant4b889672010-11-19 01:38:58 +0000[diff] [blame]221<li><a href="type_traits_design.html"><tt>&lt;type_traits&gt;</tt></a></li>
Marshall Clow928f65a2013-03-14 19:00:34 +0000[diff] [blame]222<li><a href="http://cplusplusmusings.wordpress.com/2012/07/05/clang-and-standard-libraries-on-mac-os-x/">Excellent notes by Marshall Clow</a></li>
Howard Hinnant1de22662010-10-05 16:44:40 +0000[diff] [blame]223</ul>
224
Howard Hinnant3e519522010-05-11 19:42:16 +0000[diff] [blame]225</div>
226</body>
Chris Lattner6f12a7f2010-05-11 20:37:52 +0000[diff] [blame]227</html>