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Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]17
Howard Hinnantc51e1022010-05-11 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 Lattner3c9af342010-05-11 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 Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]27 <a href="http://llvm.org/bugs/">Bug Reports</a>
Howard Hinnant00171852010-05-11 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 Hinnantc51e1022010-05-11 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 Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]37
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]38 <p>libc++ is a new implementation of the C++ standard library, targeting
Howard Hinnantd04724c2012-07-19 15:57:51 +0000[diff] [blame]39 C++11.</p>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]40
Chris Lattner7b2aacc2010-11-16 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 Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]44
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]45 <!--=====================================================================-->
46 <h2 id="goals">Features and Goals</h2>
47 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]48
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]49 <ul>
Howard Hinnantd04724c2012-07-19 15:57:51 +0000[diff] [blame]50 <li>Correctness as defined by the C++11 standard.</li>
Howard Hinnantc51e1022010-05-11 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 Clowb6a04fe2012-11-14 16:31:15 +0000[diff] [blame]60 <h2 id="why">Why a new C++ Standard Library for C++11?</h2>
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]61 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]62
Chris Lattnere2b07272010-05-12 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 Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]67
Chris Lattnere2b07272010-05-12 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 Clowb6a04fe2012-11-14 16:31:15 +0000[diff] [blame]75 machines (particularly in C++11, which has rvalue references). Breaking
Chris Lattnerc67061b2010-05-12 22:30:22 +0000[diff] [blame]76 ABI compatibility with old versions of the library was
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]77 determined to be critical to achieving the performance goals of
78 libc++.</p></li>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]79
Chris Lattnere2b07272010-05-12 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 Clowb6a04fe2012-11-14 16:31:15 +0000[diff] [blame]82 independently extended to support C++11, but this would be a fork of the
Chris Lattnere7bdfe62010-05-12 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 Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]87 </li>
88
89 <li><p>STLport and the Apache libstdcxx library are two other popular
Marshall Clowb6a04fe2012-11-14 16:31:15 +0000[diff] [blame]90 candidates, but both lack C++11 support. Our experience (and the
Howard Hinnantd04724c2012-07-19 15:57:51 +0000[diff] [blame]91 experience of libstdc++ developers) is that adding support for C++11 (in
Chris Lattnere2b07272010-05-12 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 Lattner48035ce2010-05-12 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 Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]96
Chris Lattnere2b07272010-05-12 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 Hinnantc51e1022010-05-11 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 Hinnantd04724c2012-07-19 15:57:51 +0000[diff] [blame]107 clang (lack of C++11 language support disables some functionality).</p>
Howard Hinnantc51e1022010-05-11 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 Hinnant09ce6822012-11-27 18:52:32 +0000[diff] [blame]118 <p>libc++ is a 100% complete C++11 implementation on Apple's OS X. </p>
Michael J. Spencera86f97e2012-12-31 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 Clow022f0922013-08-13 14:58:39 +0000[diff] [blame]120 <p>C++1Y (C++14) implementation is in progress. The current status is
Marshall Clow2fd05462013-08-13 14:59:44 +0000[diff] [blame^]121 <a href="cxx1y_status.html">here</a></p>
Marshall Clow022f0922013-08-13 14:58:39 +0000[diff] [blame]122
Howard Hinnant2347d2f2011-09-28 15:44:39 +0000[diff] [blame]123 <p>
Howard Hinnante1a0abb2012-07-31 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 Hinnant2347d2f2011-09-28 15:44:39 +0000[diff] [blame]127 </p>
128
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]129 <!--=====================================================================-->
130 <h2>Get it and get involved!</h2>
131 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]132
Howard Hinnantf0721aa2011-09-30 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 Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]136 <p>To check out the code, use:</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]137
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]138 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]139 <li><code>svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx</code></li>
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]140 </ul>
141
Howard Hinnantbec2fd52011-11-17 17:14:16 +0000[diff] [blame]142 <p>
Howard Hinnant79d6bcc2012-11-06 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 Hinnantbec2fd52011-11-17 17:14:16 +0000[diff] [blame]144 Xcode 4.2 or later. However if you want to install tip-of-trunk from here
Howard Hinnant961a7352012-04-03 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 Hinnantbec2fd52011-11-17 17:14:16 +0000[diff] [blame]148 </p>
149
Howard Hinnantefc7aa22011-01-27 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 Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]158 <li><code>ln -sf libc++.1.dylib libc++.dylib</code></li>
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]159 </ul>
160
161 <p>
Howard Hinnant79d6bcc2012-11-06 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 Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]165 </p>
166
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]167 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]168 To use your system-installed libc++ with clang you can:
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]169 </p>
170
171 <ul>
172 <li><code>clang++ -stdlib=libc++ test.cpp</code></li>
Howard Hinnantd04724c2012-07-19 15:57:51 +0000[diff] [blame]173 <li><code>clang++ -std=c++11 -stdlib=libc++ test.cpp</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]174 </ul>
175
Howard Hinnant79d6bcc2012-11-06 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 Clowbd02bde2012-08-22 00:57:11 +0000[diff] [blame]187 <p>To run the libc++ test suite (recommended):</p>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]188
189 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]190 <li><code>cd libcxx/test</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]191 <li><code>./testit</code></li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]192 <ul>
Howard Hinnant79d6bcc2012-11-06 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 Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]195 </ul>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]196 </ul>
197
Howard Hinnant24147cf2012-05-20 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 Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]207 <p>Send discussions to the
Howard Hinnantc5b02f22010-05-11 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 Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]210 <!--=====================================================================-->
Michael J. Spencera86f97e2012-12-31 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"
251 -DLIBCXX_CXX_ABI=libsupc++
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>
256 <li><code>make</code></li>
257 <li><code>sudo make install</code></li>
258 </ul>
259 <p>
260 You can now run clang with -stdlib=libc++.
261 </p>
262 </p>
263
264 <!--=====================================================================-->
Howard Hinnant8d3824d2013-02-08 19:10:36 +0000[diff] [blame]265 <h2>Build on Linux using CMake and libc++abi.</h2>
266 <!--=====================================================================-->
267
268 <p>
269 You will need to keep the source tree of <a href="http://libcxxabi.llvm.org">libc++abi</a>
270 available on your build machine and your copy of the libc++abi shared library must
271 be placed where your linker will find it.
272 </p>
273
274 <p>
275 We can now run CMake:
276 <ul>
277 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
278 -DLIBCXX_CXX_ABI=libcxxabi
279 -DLIBCXX_LIBCXXABI_INCLUDE_PATHS="&lt;libc++abi-source-dir&gt;/include"
280 -DCMAKE_BUILD_TYPE=Release
281 -DCMAKE_INSTALL_PREFIX=/usr
282 &lt;libc++-source-dir&gt;</code></li>
283 <li><code>make</code></li>
284 <li><code>sudo make install</code></li>
285 </ul>
286 <p>
287 Unfortunately you can't simply run clang with "-stdlib=libc++" at this point, as
288 clang is set up to link for libc++ linked to libsupc++. To get around this
289 you'll have to set up your linker yourself (or patch clang). For example,
290 <ul>
291 <li><code>clang++ -stdlib=libc++ helloworld.cpp -nodefaultlibs -lc++ -lc++abi -lm -lc -lgcc_s -lgcc</code></li>
292 </ul>
293 Alternately, you could just add libc++abi to your libraries list, which in most
294 situations will give the same result:
295 <ul>
296 <li><code>clang++ -stdlib=libc++ helloworld.cpp -lc++abi</code></li>
297 </ul>
298 </p>
299 </p>
300
301 <!--=====================================================================-->
302 <h2>Build on Linux using CMake and libcxxrt.</h2>
303 <!--=====================================================================-->
304
305 <p>
306 You will need to keep the source tree of
307 <a href="https://github.com/pathscale/libcxxrt/">libcxxrt</a> available
308 on your build machine and your copy of the libcxxrt shared library must
309 be placed where your linker will find it.
310 </p>
311
312 <p>
313 We can now run CMake:
314 <ul>
315 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
316 -DLIBCXX_CXX_ABI=libcxxrt
Howard Hinnant727ff912013-02-26 16:27:55 +0000[diff] [blame]317 -DLIBCXX_LIBCXXRT_INCLUDE_PATHS="&lt;libcxxrt-source-dir&gt;/src"
Howard Hinnant8d3824d2013-02-08 19:10:36 +0000[diff] [blame]318 -DCMAKE_BUILD_TYPE=Release
319 -DCMAKE_INSTALL_PREFIX=/usr
320 &lt;libc++-source-dir&gt;</code></li>
321 <li><code>make</code></li>
322 <li><code>sudo make install</code></li>
323 </ul>
324 <p>
325 Unfortunately you can't simply run clang with "-stdlib=libc++" at this point, as
326 clang is set up to link for libc++ linked to libsupc++. To get around this
327 you'll have to set up your linker yourself (or patch clang). For example,
328 <ul>
329 <li><code>clang++ -stdlib=libc++ helloworld.cpp -nodefaultlibs -lc++ -lcxxrt -lm -lc -lgcc_s -lgcc</code></li>
330 </ul>
331 Alternately, you could just add libcxxrt to your libraries list, which in most
332 situations will give the same result:
333 <ul>
334 <li><code>clang++ -stdlib=libc++ helloworld.cpp -lcxxrt</code></li>
335 </ul>
336 </p>
337 </p>
338
339 <!--=====================================================================-->
Howard Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]340 <h2>Design Documents</h2>
341 <!--=====================================================================-->
342
343<ul>
344<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
Howard Hinnante20b8de2010-11-19 01:38:58 +0000[diff] [blame]345<li><a href="type_traits_design.html"><tt>&lt;type_traits&gt;</tt></a></li>
Marshall Clow68aa6b42013-03-14 19:00:34 +0000[diff] [blame]346<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 +0000[diff] [blame]347<li><a href="debug_mode.html">Status of debug mode</a></li>
Howard Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]348</ul>
349
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]350</div>
351</body>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]352</html>