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Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]17
Howard Hinnantbc8d3f92010-05-11 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>
Chris Lattnera535ffd2010-05-11 20:53:16 +0000[diff] [blame]25 <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 Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]27 <a href="http://llvm.org/bugs/">Bug Reports</a>
Howard Hinnant76e1ffc2010-05-11 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 Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]30 </div>
31</div>
32
33<div id="content">
34 <!--*********************************************************************-->
35 <h1>"libc++" C++ Standard Library</h1>
36 <!--*********************************************************************-->
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]37
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]38 <p>libc++ is a new implementation of the C++ standard library, targeting
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]39 C++11.</p>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]40
Chris Lattnerf38bc6e2010-11-16 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 Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]44
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]45 <!--=====================================================================-->
46 <h2 id="goals">Features and Goals</h2>
47 <!--=====================================================================-->
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]48
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]49 <ul>
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]50 <li>Correctness as defined by the C++11 standard.</li>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]51 <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 Clowfaa17162012-11-14 16:31:15 +0000[diff] [blame]60 <h2 id="why">Why a new C++ Standard Library for C++11?</h2>
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]61 <!--=====================================================================-->
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]62
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]63 <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 Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]67
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]68 <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 Clowfaa17162012-11-14 16:31:15 +0000[diff] [blame]75 machines (particularly in C++11, which has rvalue references). Breaking
Chris Lattnera5058d92010-05-12 22:30:22 +0000[diff] [blame]76 ABI compatibility with old versions of the library was
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]77 determined to be critical to achieving the performance goals of
78 libc++.</p></li>
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]79
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]80 <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 Clowfaa17162012-11-14 16:31:15 +0000[diff] [blame]82 independently extended to support C++11, but this would be a fork of the
Chris Lattnerf3382492010-05-12 22:33:00 +0000[diff] [blame]83 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 Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]87 </li>
88
89 <li><p>STLport and the Apache libstdcxx library are two other popular
Marshall Clowfaa17162012-11-14 16:31:15 +0000[diff] [blame]90 candidates, but both lack C++11 support. Our experience (and the
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]91 experience of libstdc++ developers) is that adding support for C++11 (in
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]92 particular rvalue references and move-only types) requires changes to
93 almost every class and function, essentially amounting to a rewrite.
Chris Lattnerbfa808e2010-05-12 22:34:21 +0000[diff] [blame]94 Faced with a rewrite, we decided to start from scratch and evaluate every
95 design decision from first principles based on experience.</p>
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]96
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]97 <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 Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]103 <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 Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]107 clang (lack of C++11 language support disables some functionality).</p>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]108
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 Hinnantb0895ff2012-11-27 18:52:32 +0000[diff] [blame]118 <p>libc++ is a 100% complete C++11 implementation on Apple's OS X. </p>
Michael J. Spencerdb8a0302012-12-31 19:34:21 +0000[diff] [blame]119 <p>LLVM and Clang can self host in C++ and C++11 mode with libc++ on Linux.</p>
Marshall Clow5d480772013-08-13 14:58:39 +0000[diff] [blame]120 <p>C++1Y (C++14) implementation is in progress. The current status is
Marshall Clow437cdcf2013-08-13 14:59:44 +0000[diff] [blame]121 <a href="cxx1y_status.html">here</a></p>
Marshall Clow5d480772013-08-13 14:58:39 +0000[diff] [blame]122
Howard Hinnant0cbb3a12011-09-28 15:44:39 +0000[diff] [blame]123 <p>
Howard Hinnantee7a0bf2012-07-31 21:30:28 +0000[diff] [blame]124 Ports to other platforms are underway. Here are recent test
125 results for <a href="results.Windows.html">Windows</a>
126 and <a href="results.Linux.html">Linux</a>.
Howard Hinnant0cbb3a12011-09-28 15:44:39 +0000[diff] [blame]127 </p>
128
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]129 <!--=====================================================================-->
130 <h2>Get it and get involved!</h2>
131 <!--=====================================================================-->
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]132
Howard Hinnant2481cba2011-09-30 16:58:02 +0000[diff] [blame]133 <p>First please review our
134 <a href="http://llvm.org/docs/DeveloperPolicy.html">Developer's Policy</a>.
135
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]136 <p>To check out the code, use:</p>
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]137
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]138 <ul>
Chris Lattner4b748952010-05-11 20:37:52 +0000[diff] [blame]139 <li><code>svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx</code></li>
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]140 </ul>
141
Howard Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]142 <p>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]143 On Mac OS 10.7 (Lion) and later, the easiest way to get this library is to install
Howard Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]144 Xcode 4.2 or later. However if you want to install tip-of-trunk from here
Howard Hinnant271a1c02012-04-03 15:08:42 +0000[diff] [blame]145 (getting the bleeding edge), read on. However, be warned that Mac OS
146 10.7 will not boot without a valid copy of <code>libc++.1.dylib</code> in
147 <code>/usr/lib</code>.
Howard Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]148 </p>
149
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]150 <p>
151 Next:
152 </p>
153
154 <ul>
155 <li><code>cd libcxx/lib</code></li>
156 <li><code>export TRIPLE=-apple-</code></li>
157 <li><code>./buildit</code></li>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]158 <li><code>ln -sf libc++.1.dylib libc++.dylib</code></li>
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]159 </ul>
160
161 <p>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]162 That should result in a libc++.1.dylib and libc++.dylib. The safest thing
163 to do is to use it from where your libcxx is installed instead of replacing
164 these in your Mac OS.
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]165 </p>
166
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]167 <p>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]168 To use your system-installed libc++ with clang you can:
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]169 </p>
170
171 <ul>
172 <li><code>clang++ -stdlib=libc++ test.cpp</code></li>
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]173 <li><code>clang++ -std=c++11 -stdlib=libc++ test.cpp</code></li>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]174 </ul>
175
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]176 <p>
177 To use your tip-of-trunk libc++ on Mac OS with clang you can:
178 </p>
179
180 <ul>
181 <li><code>export DYLD_LIBRARY_PATH=&lt;path-to-libcxx&gt;/lib</code>
182 <li><code>clang++ -std=c++11 -stdlib=libc++ -nostdinc++
183 -I&lt;path-to-libcxx&gt;/include -L&lt;path-to-libcxx&gt;/lib
184 test.cpp</code></li>
185 </ul>
186
Marshall Clow08a0b482012-08-22 00:57:11 +0000[diff] [blame]187 <p>To run the libc++ test suite (recommended):</p>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]188
189 <ul>
Chris Lattner4b748952010-05-11 20:37:52 +0000[diff] [blame]190 <li><code>cd libcxx/test</code></li>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]191 <li><code>./testit</code></li>
Howard Hinnantf5d76a72011-06-22 12:13:55 +0000[diff] [blame]192 <ul>
Howard Hinnant22b781b2012-11-06 21:31:37 +0000[diff] [blame]193 <li>You can alter the command line options <code>testit</code> uses
194 with <code>export OPTIONS="whatever you need"</code></li>
Howard Hinnantf5d76a72011-06-22 12:13:55 +0000[diff] [blame]195 </ul>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]196 </ul>
197
Howard Hinnant51065652012-05-20 13:03:53 +0000[diff] [blame]198 <!--=====================================================================-->
199 <h3>Notes</h3>
200 <!--=====================================================================-->
201
202<p>
203Building libc++ with <code>-fno-rtti</code> is not supported. However linking
204against it with <code>-fno-rtti</code> is supported.
205</p>
206
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]207 <p>Send discussions to the
Howard Hinnant8c217372010-05-11 19:53:34 +0000[diff] [blame]208 (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p>
209
Howard Hinnant56f0d5b2010-10-05 16:44:40 +0000[diff] [blame]210 <!--=====================================================================-->
Michael J. Spencerdb8a0302012-12-31 19:34:21 +0000[diff] [blame]211 <h2>Build on Linux using CMake and libsupc++.</h2>
212 <!--=====================================================================-->
213
214 <p>
215 You will need libstdc++ in order to provide libsupc++.
216 </p>
217
218 <p>
219 Figure out where the libsupc++ headers are on your system. On Ubuntu this
220 is <code>/usr/include/c++/&lt;version&gt;</code> and
221 <code>/usr/include/c++/&lt;version&gt;/&lt;target-triple&gt;</code>
222 </p>
223
224 <p>
225 You can also figure this out by running
226 <pre>
227$ echo | g++ -Wp,-v -x c++ - -fsyntax-only
228ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
229ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../x86_64-linux-gnu/include"
230#include "..." search starts here:
231#include &lt;...&gt; search starts here:
232 /usr/include/c++/4.7
233 /usr/include/c++/4.7/x86_64-linux-gnu
234 /usr/include/c++/4.7/backward
235 /usr/lib/gcc/x86_64-linux-gnu/4.7/include
236 /usr/local/include
237 /usr/lib/gcc/x86_64-linux-gnu/4.7/include-fixed
238 /usr/include/x86_64-linux-gnu
239 /usr/include
240End of search list.
241 </pre>
242
243 Note the first two entries happen to be what we are looking for. This
244 may not be correct on other platforms.
245 </p>
246
247 <p>
248 We can now run CMake:
249 <ul>
250 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
Peter Collingbourned0d308f2013-10-06 22:13:19 +0000[diff] [blame^]251 -DLIBCXX_CXX_ABI=libstdc++
Michael J. Spencerdb8a0302012-12-31 19:34:21 +0000[diff] [blame]252 -DLIBCXX_LIBSUPCXX_INCLUDE_PATHS="/usr/include/c++/4.7/;/usr/include/c++/4.7/x86_64-linux-gnu/"
253 -DCMAKE_BUILD_TYPE=Release
254 -DCMAKE_INSTALL_PREFIX=/usr
255 &lt;libc++-source-dir&gt;</code></li>
Peter Collingbourned0d308f2013-10-06 22:13:19 +0000[diff] [blame^]256 <li>You can also substitute <code>-DLIBCXX_CXX_ABI=libsupc++</code>
257 above, which will cause the library to be linked to libsupc++ instead
258 of libstdc++, but this is only recommended if you know that you will
259 never need to link against libstdc++ in the same executable as libc++.
260 GCC ships libsupc++ separately but only as a static library. If a
261 program also needs to link against libstdc++, it will provide its
262 own copy of libsupc++ and this can lead to subtle problems.
Michael J. Spencerdb8a0302012-12-31 19:34:21 +0000[diff] [blame]263 <li><code>make</code></li>
264 <li><code>sudo make install</code></li>
265 </ul>
266 <p>
267 You can now run clang with -stdlib=libc++.
268 </p>
269 </p>
270
271 <!--=====================================================================-->
Howard Hinnantaf4d1612013-02-08 19:10:36 +0000[diff] [blame]272 <h2>Build on Linux using CMake and libc++abi.</h2>
273 <!--=====================================================================-->
274
275 <p>
276 You will need to keep the source tree of <a href="http://libcxxabi.llvm.org">libc++abi</a>
277 available on your build machine and your copy of the libc++abi shared library must
278 be placed where your linker will find it.
279 </p>
280
281 <p>
282 We can now run CMake:
283 <ul>
284 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
285 -DLIBCXX_CXX_ABI=libcxxabi
286 -DLIBCXX_LIBCXXABI_INCLUDE_PATHS="&lt;libc++abi-source-dir&gt;/include"
287 -DCMAKE_BUILD_TYPE=Release
288 -DCMAKE_INSTALL_PREFIX=/usr
289 &lt;libc++-source-dir&gt;</code></li>
290 <li><code>make</code></li>
291 <li><code>sudo make install</code></li>
292 </ul>
293 <p>
294 Unfortunately you can't simply run clang with "-stdlib=libc++" at this point, as
295 clang is set up to link for libc++ linked to libsupc++. To get around this
296 you'll have to set up your linker yourself (or patch clang). For example,
297 <ul>
298 <li><code>clang++ -stdlib=libc++ helloworld.cpp -nodefaultlibs -lc++ -lc++abi -lm -lc -lgcc_s -lgcc</code></li>
299 </ul>
300 Alternately, you could just add libc++abi to your libraries list, which in most
301 situations will give the same result:
302 <ul>
303 <li><code>clang++ -stdlib=libc++ helloworld.cpp -lc++abi</code></li>
304 </ul>
305 </p>
306 </p>
307
308 <!--=====================================================================-->
309 <h2>Build on Linux using CMake and libcxxrt.</h2>
310 <!--=====================================================================-->
311
312 <p>
313 You will need to keep the source tree of
314 <a href="https://github.com/pathscale/libcxxrt/">libcxxrt</a> available
315 on your build machine and your copy of the libcxxrt shared library must
316 be placed where your linker will find it.
317 </p>
318
319 <p>
320 We can now run CMake:
321 <ul>
322 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
323 -DLIBCXX_CXX_ABI=libcxxrt
Howard Hinnantfae54b92013-02-26 16:27:55 +0000[diff] [blame]324 -DLIBCXX_LIBCXXRT_INCLUDE_PATHS="&lt;libcxxrt-source-dir&gt;/src"
Howard Hinnantaf4d1612013-02-08 19:10:36 +0000[diff] [blame]325 -DCMAKE_BUILD_TYPE=Release
326 -DCMAKE_INSTALL_PREFIX=/usr
327 &lt;libc++-source-dir&gt;</code></li>
328 <li><code>make</code></li>
329 <li><code>sudo make install</code></li>
330 </ul>
331 <p>
332 Unfortunately you can't simply run clang with "-stdlib=libc++" at this point, as
333 clang is set up to link for libc++ linked to libsupc++. To get around this
334 you'll have to set up your linker yourself (or patch clang). For example,
335 <ul>
336 <li><code>clang++ -stdlib=libc++ helloworld.cpp -nodefaultlibs -lc++ -lcxxrt -lm -lc -lgcc_s -lgcc</code></li>
337 </ul>
338 Alternately, you could just add libcxxrt to your libraries list, which in most
339 situations will give the same result:
340 <ul>
341 <li><code>clang++ -stdlib=libc++ helloworld.cpp -lcxxrt</code></li>
342 </ul>
343 </p>
344 </p>
345
346 <!--=====================================================================-->
Howard Hinnant56f0d5b2010-10-05 16:44:40 +0000[diff] [blame]347 <h2>Design Documents</h2>
348 <!--=====================================================================-->
349
350<ul>
351<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
Howard Hinnant9835d762010-11-19 01:38:58 +0000[diff] [blame]352<li><a href="type_traits_design.html"><tt>&lt;type_traits&gt;</tt></a></li>
Marshall Clowe47bc9b2013-03-14 19:00:34 +0000[diff] [blame]353<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 Hinnantc7cbe502013-03-14 18:37:48 +0000[diff] [blame]354<li><a href="debug_mode.html">Status of debug mode</a></li>
Howard Hinnant56f0d5b2010-10-05 16:44:40 +0000[diff] [blame]355</ul>
356
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]357</div>
358</body>
Chris Lattner4b748952010-05-11 20:37:52 +0000[diff] [blame]359</html>