blob: c62b97105ba86ce2e49bc0f2c1a27edd3fb3df4d [file] [log] [blame]
Howard Hinnant3e1b0422010-08-22 01:04:38 +00001<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
Howard Hinnantc51e1022010-05-11 19:42:16 +00002 "http://www.w3.org/TR/html4/strict.dtd">
3<!-- Material used from: HTML 4.01 specs: http://www.w3.org/TR/html401/ -->
4<html>
5<head>
6 <META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
7 <title>"libc++" C++ Standard Library</title>
8 <link type="text/css" rel="stylesheet" href="menu.css">
9 <link type="text/css" rel="stylesheet" href="content.css">
10</head>
11
12<body>
13<div id="menu">
14 <div>
15 <a href="http://llvm.org/">LLVM Home</a>
16 </div>
Howard Hinnant3e1b0422010-08-22 01:04:38 +000017
Howard Hinnantc51e1022010-05-11 19:42:16 +000018 <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>
Chris Lattner3c9af342010-05-11 20:53:16 +000025 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">cfe-dev</a>
26 <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits">cfe-commits</a>
Howard Hinnantc51e1022010-05-11 19:42:16 +000027 <a href="http://llvm.org/bugs/">Bug Reports</a>
Howard Hinnant00171852010-05-11 20:51:20 +000028 <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 Hinnantc51e1022010-05-11 19:42:16 +000030 </div>
31</div>
32
33<div id="content">
34 <!--*********************************************************************-->
35 <h1>"libc++" C++ Standard Library</h1>
36 <!--*********************************************************************-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +000037
Howard Hinnantc51e1022010-05-11 19:42:16 +000038 <p>libc++ is a new implementation of the C++ standard library, targeting
Howard Hinnantd04724c2012-07-19 15:57:51 +000039 C++11.</p>
Howard Hinnantc51e1022010-05-11 19:42:16 +000040
Chris Lattner7b2aacc2010-11-16 21:40:19 +000041 <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 Hinnant3e1b0422010-08-22 01:04:38 +000044
Howard Hinnantc51e1022010-05-11 19:42:16 +000045 <!--=====================================================================-->
46 <h2 id="goals">Features and Goals</h2>
47 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +000048
Howard Hinnantc51e1022010-05-11 19:42:16 +000049 <ul>
Howard Hinnantd04724c2012-07-19 15:57:51 +000050 <li>Correctness as defined by the C++11 standard.</li>
Howard Hinnantc51e1022010-05-11 19:42:16 +000051 <li>Fast execution.</li>
52 <li>Minimal memory use.</li>
53 <li>Fast compile times.</li>
54 <li>ABI compatibility with gcc's libstdc++ for some low-level features
55 such as exception objects, rtti and memory allocation.</li>
56 <li>Extensive unit tests.</li>
57 </ul>
58
59 <!--=====================================================================-->
Marshall Clowb6a04fe2012-11-14 16:31:15 +000060 <h2 id="why">Why a new C++ Standard Library for C++11?</h2>
Chris Lattnere2b07272010-05-12 22:21:15 +000061 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +000062
Chris Lattnere2b07272010-05-12 22:21:15 +000063 <p>After its initial introduction, many people have asked "why start a new
64 library instead of contributing to an existing library?" (like Apache's
65 libstdcxx, GNU's libstdc++, STLport, etc). There are many contributing
66 reasons, but some of the major ones are:</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +000067
Chris Lattnere2b07272010-05-12 22:21:15 +000068 <ul>
69 <li><p>From years of experience (including having implemented the standard
70 library before), we've learned many things about implementing
71 the standard containers which require ABI breakage and fundamental changes
72 to how they are implemented. For example, it is generally accepted that
73 building std::string using the "short string optimization" instead of
74 using Copy On Write (COW) is a superior approach for multicore
Marshall Clowb6a04fe2012-11-14 16:31:15 +000075 machines (particularly in C++11, which has rvalue references). Breaking
Chris Lattnerc67061b2010-05-12 22:30:22 +000076 ABI compatibility with old versions of the library was
Chris Lattnere2b07272010-05-12 22:21:15 +000077 determined to be critical to achieving the performance goals of
78 libc++.</p></li>
Howard Hinnant3e1b0422010-08-22 01:04:38 +000079
Chris Lattnere2b07272010-05-12 22:21:15 +000080 <li><p>Mainline libstdc++ has switched to GPL3, a license which the developers
81 of libc++ cannot use. libstdc++ 4.2 (the last GPL2 version) could be
Marshall Clowb6a04fe2012-11-14 16:31:15 +000082 independently extended to support C++11, but this would be a fork of the
Chris Lattnere7bdfe62010-05-12 22:33:00 +000083 codebase (which is often seen as worse for a project than starting a new
84 independent one). Another problem with libstdc++ is that it is tightly
85 integrated with G++ development, tending to be tied fairly closely to the
86 matching version of G++.</p>
Chris Lattnere2b07272010-05-12 22:21:15 +000087 </li>
88
89 <li><p>STLport and the Apache libstdcxx library are two other popular
Marshall Clowb6a04fe2012-11-14 16:31:15 +000090 candidates, but both lack C++11 support. Our experience (and the
Howard Hinnantd04724c2012-07-19 15:57:51 +000091 experience of libstdc++ developers) is that adding support for C++11 (in
Chris Lattnere2b07272010-05-12 22:21:15 +000092 particular rvalue references and move-only types) requires changes to
93 almost every class and function, essentially amounting to a rewrite.
Chris Lattner48035ce2010-05-12 22:34:21 +000094 Faced with a rewrite, we decided to start from scratch and evaluate every
95 design decision from first principles based on experience.</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +000096
Chris Lattnere2b07272010-05-12 22:21:15 +000097 <p>Further, both projects are apparently abandoned: STLport 5.2.1 was
98 released in Oct'08, and STDCXX 4.2.1 in May'08.</p>
99
100 </ul>
101
102 <!--=====================================================================-->
Howard Hinnantc51e1022010-05-11 19:42:16 +0000103 <h2 id="requirements">Platform Support</h2>
104 <!--=====================================================================-->
105
106 <p>libc++ is known to work on the following platforms, using g++-4.2 and
Howard Hinnantd04724c2012-07-19 15:57:51 +0000107 clang (lack of C++11 language support disables some functionality).</p>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000108
109 <ul>
110 <li>Mac OS X i386</li>
111 <li>Mac OS X x86_64</li>
112 </ul>
113
114 <!--=====================================================================-->
115 <h2 id="dir-structure">Current Status</h2>
116 <!--=====================================================================-->
117
Howard Hinnant09ce6822012-11-27 18:52:32 +0000118 <p>libc++ is a 100% complete C++11 implementation on Apple's OS X. </p>
Michael J. Spencera86f97e2012-12-31 19:34:21 +0000119 <p>LLVM and Clang can self host in C++ and C++11 mode with libc++ on Linux.</p>
Marshall Clow979d36a2014-04-03 02:38:12 +0000120 <p>libc++ is also a 100% complete C++14 implementation. A list of new features and changes for
Marshall Clow6d44d712014-04-03 02:35:29 +0000121 C++14 can be found <a href="cxx1y_status.html">here</a>.</p>
Howard Hinnant2347d2f2011-09-28 15:44:39 +0000122 <p>
Howard Hinnante1a0abb2012-07-31 21:30:28 +0000123 Ports to other platforms are underway. Here are recent test
124 results for <a href="results.Windows.html">Windows</a>
125 and <a href="results.Linux.html">Linux</a>.
Howard Hinnant2347d2f2011-09-28 15:44:39 +0000126 </p>
127
Howard Hinnantc51e1022010-05-11 19:42:16 +0000128 <!--=====================================================================-->
129 <h2>Get it and get involved!</h2>
130 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000131
Howard Hinnantf0721aa2011-09-30 16:58:02 +0000132 <p>First please review our
133 <a href="http://llvm.org/docs/DeveloperPolicy.html">Developer's Policy</a>.
134
Howard Hinnantc51e1022010-05-11 19:42:16 +0000135 <p>To check out the code, use:</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000136
Howard Hinnantc51e1022010-05-11 19:42:16 +0000137 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000138 <li><code>svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx</code></li>
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000139 </ul>
140
Howard Hinnantbec2fd52011-11-17 17:14:16 +0000141 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000142 On Mac OS 10.7 (Lion) and later, the easiest way to get this library is to install
Howard Hinnantbec2fd52011-11-17 17:14:16 +0000143 Xcode 4.2 or later. However if you want to install tip-of-trunk from here
Howard Hinnant961a7352012-04-03 15:08:42 +0000144 (getting the bleeding edge), read on. However, be warned that Mac OS
145 10.7 will not boot without a valid copy of <code>libc++.1.dylib</code> in
146 <code>/usr/lib</code>.
Howard Hinnantbec2fd52011-11-17 17:14:16 +0000147 </p>
148
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000149 <p>
150 Next:
151 </p>
152
153 <ul>
154 <li><code>cd libcxx/lib</code></li>
155 <li><code>export TRIPLE=-apple-</code></li>
156 <li><code>./buildit</code></li>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000157 <li><code>ln -sf libc++.1.dylib libc++.dylib</code></li>
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000158 </ul>
159
160 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000161 That should result in a libc++.1.dylib and libc++.dylib. The safest thing
162 to do is to use it from where your libcxx is installed instead of replacing
163 these in your Mac OS.
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000164 </p>
165
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000166 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000167 To use your system-installed libc++ with clang you can:
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000168 </p>
169
170 <ul>
171 <li><code>clang++ -stdlib=libc++ test.cpp</code></li>
Howard Hinnantd04724c2012-07-19 15:57:51 +0000172 <li><code>clang++ -std=c++11 -stdlib=libc++ test.cpp</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000173 </ul>
174
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000175 <p>
176 To use your tip-of-trunk libc++ on Mac OS with clang you can:
177 </p>
178
179 <ul>
180 <li><code>export DYLD_LIBRARY_PATH=&lt;path-to-libcxx&gt;/lib</code>
181 <li><code>clang++ -std=c++11 -stdlib=libc++ -nostdinc++
182 -I&lt;path-to-libcxx&gt;/include -L&lt;path-to-libcxx&gt;/lib
183 test.cpp</code></li>
184 </ul>
185
Marshall Clowbd02bde2012-08-22 00:57:11 +0000186 <p>To run the libc++ test suite (recommended):</p>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000187
188 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000189 <li><code>cd libcxx/test</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000190 <li><code>./testit</code></li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000191 <ul>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000192 <li>You can alter the command line options <code>testit</code> uses
193 with <code>export OPTIONS="whatever you need"</code></li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000194 </ul>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000195 </ul>
196
Howard Hinnant24147cf2012-05-20 13:03:53 +0000197 <!--=====================================================================-->
198 <h3>Notes</h3>
199 <!--=====================================================================-->
200
201<p>
202Building libc++ with <code>-fno-rtti</code> is not supported. However linking
203against it with <code>-fno-rtti</code> is supported.
204</p>
205
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000206 <p>Send discussions to the
Howard Hinnantc5b02f22010-05-11 19:53:34 +0000207 (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p>
208
Howard Hinnantbded6c92010-10-05 16:44:40 +0000209 <!--=====================================================================-->
Marshall Clowf7cc9a12014-04-03 03:13:12 +0000210 <h2>Bug reports and patches</h2>
211 <!--=====================================================================-->
212
213<p>
214If you think you've found a bug in libc++, please report it using
215the <a href="http://llvm.org/bugs">LLVM Bugzilla</a>. If you're not sure, you
216can post a meesage to the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">cfe-dev</a>
217mailing list or on IRC. Please include "libc++" in your subject.
218</p>
219
220<p>
221If you want to contribute a patch to libc++, the best place for that is the
222<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits">cfe-commits</a>
223mailing list. Please include "libc++" and "PATCH" in your subject.
224</p>
225
226 <!--=====================================================================-->
Michael J. Spencera86f97e2012-12-31 19:34:21 +0000227 <h2>Build on Linux using CMake and libsupc++.</h2>
228 <!--=====================================================================-->
229
230 <p>
231 You will need libstdc++ in order to provide libsupc++.
232 </p>
233
234 <p>
235 Figure out where the libsupc++ headers are on your system. On Ubuntu this
236 is <code>/usr/include/c++/&lt;version&gt;</code> and
237 <code>/usr/include/c++/&lt;version&gt;/&lt;target-triple&gt;</code>
238 </p>
239
240 <p>
241 You can also figure this out by running
242 <pre>
243$ echo | g++ -Wp,-v -x c++ - -fsyntax-only
244ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
245ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../x86_64-linux-gnu/include"
246#include "..." search starts here:
247#include &lt;...&gt; search starts here:
248 /usr/include/c++/4.7
249 /usr/include/c++/4.7/x86_64-linux-gnu
250 /usr/include/c++/4.7/backward
251 /usr/lib/gcc/x86_64-linux-gnu/4.7/include
252 /usr/local/include
253 /usr/lib/gcc/x86_64-linux-gnu/4.7/include-fixed
254 /usr/include/x86_64-linux-gnu
255 /usr/include
256End of search list.
257 </pre>
258
259 Note the first two entries happen to be what we are looking for. This
260 may not be correct on other platforms.
261 </p>
262
263 <p>
264 We can now run CMake:
265 <ul>
266 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
Peter Collingbourne22dc63b2013-10-06 22:13:19 +0000267 -DLIBCXX_CXX_ABI=libstdc++
Michael J. Spencera86f97e2012-12-31 19:34:21 +0000268 -DLIBCXX_LIBSUPCXX_INCLUDE_PATHS="/usr/include/c++/4.7/;/usr/include/c++/4.7/x86_64-linux-gnu/"
269 -DCMAKE_BUILD_TYPE=Release
270 -DCMAKE_INSTALL_PREFIX=/usr
271 &lt;libc++-source-dir&gt;</code></li>
Peter Collingbourne22dc63b2013-10-06 22:13:19 +0000272 <li>You can also substitute <code>-DLIBCXX_CXX_ABI=libsupc++</code>
273 above, which will cause the library to be linked to libsupc++ instead
274 of libstdc++, but this is only recommended if you know that you will
275 never need to link against libstdc++ in the same executable as libc++.
276 GCC ships libsupc++ separately but only as a static library. If a
277 program also needs to link against libstdc++, it will provide its
278 own copy of libsupc++ and this can lead to subtle problems.
Michael J. Spencera86f97e2012-12-31 19:34:21 +0000279 <li><code>make</code></li>
280 <li><code>sudo make install</code></li>
281 </ul>
282 <p>
283 You can now run clang with -stdlib=libc++.
284 </p>
285 </p>
286
287 <!--=====================================================================-->
Howard Hinnant8d3824d2013-02-08 19:10:36 +0000288 <h2>Build on Linux using CMake and libc++abi.</h2>
289 <!--=====================================================================-->
290
291 <p>
292 You will need to keep the source tree of <a href="http://libcxxabi.llvm.org">libc++abi</a>
293 available on your build machine and your copy of the libc++abi shared library must
294 be placed where your linker will find it.
295 </p>
296
297 <p>
298 We can now run CMake:
299 <ul>
300 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
301 -DLIBCXX_CXX_ABI=libcxxabi
302 -DLIBCXX_LIBCXXABI_INCLUDE_PATHS="&lt;libc++abi-source-dir&gt;/include"
303 -DCMAKE_BUILD_TYPE=Release
304 -DCMAKE_INSTALL_PREFIX=/usr
305 &lt;libc++-source-dir&gt;</code></li>
306 <li><code>make</code></li>
307 <li><code>sudo make install</code></li>
308 </ul>
309 <p>
310 Unfortunately you can't simply run clang with "-stdlib=libc++" at this point, as
311 clang is set up to link for libc++ linked to libsupc++. To get around this
312 you'll have to set up your linker yourself (or patch clang). For example,
313 <ul>
314 <li><code>clang++ -stdlib=libc++ helloworld.cpp -nodefaultlibs -lc++ -lc++abi -lm -lc -lgcc_s -lgcc</code></li>
315 </ul>
316 Alternately, you could just add libc++abi to your libraries list, which in most
317 situations will give the same result:
318 <ul>
319 <li><code>clang++ -stdlib=libc++ helloworld.cpp -lc++abi</code></li>
320 </ul>
321 </p>
322 </p>
323
324 <!--=====================================================================-->
325 <h2>Build on Linux using CMake and libcxxrt.</h2>
326 <!--=====================================================================-->
327
328 <p>
329 You will need to keep the source tree of
330 <a href="https://github.com/pathscale/libcxxrt/">libcxxrt</a> available
331 on your build machine and your copy of the libcxxrt shared library must
332 be placed where your linker will find it.
333 </p>
334
335 <p>
336 We can now run CMake:
337 <ul>
338 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
339 -DLIBCXX_CXX_ABI=libcxxrt
Howard Hinnant727ff912013-02-26 16:27:55 +0000340 -DLIBCXX_LIBCXXRT_INCLUDE_PATHS="&lt;libcxxrt-source-dir&gt;/src"
Howard Hinnant8d3824d2013-02-08 19:10:36 +0000341 -DCMAKE_BUILD_TYPE=Release
342 -DCMAKE_INSTALL_PREFIX=/usr
343 &lt;libc++-source-dir&gt;</code></li>
344 <li><code>make</code></li>
345 <li><code>sudo make install</code></li>
346 </ul>
347 <p>
348 Unfortunately you can't simply run clang with "-stdlib=libc++" at this point, as
349 clang is set up to link for libc++ linked to libsupc++. To get around this
350 you'll have to set up your linker yourself (or patch clang). For example,
351 <ul>
352 <li><code>clang++ -stdlib=libc++ helloworld.cpp -nodefaultlibs -lc++ -lcxxrt -lm -lc -lgcc_s -lgcc</code></li>
353 </ul>
354 Alternately, you could just add libcxxrt to your libraries list, which in most
355 situations will give the same result:
356 <ul>
357 <li><code>clang++ -stdlib=libc++ helloworld.cpp -lcxxrt</code></li>
358 </ul>
359 </p>
360 </p>
361
362 <!--=====================================================================-->
Howard Hinnantbded6c92010-10-05 16:44:40 +0000363 <h2>Design Documents</h2>
364 <!--=====================================================================-->
365
366<ul>
367<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
Howard Hinnante20b8de2010-11-19 01:38:58 +0000368<li><a href="type_traits_design.html"><tt>&lt;type_traits&gt;</tt></a></li>
Marshall Clow68aa6b42013-03-14 19:00:34 +0000369<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 Hinnant57724c32013-03-14 18:37:48 +0000370<li><a href="debug_mode.html">Status of debug mode</a></li>
Howard Hinnantbded6c92010-10-05 16:44:40 +0000371</ul>
372
Howard Hinnantc51e1022010-05-11 19:42:16 +0000373</div>
374</body>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000375</html>