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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>
Howard Hinnant075ac852010-05-13 20:10:39 +0000[diff] [blame]120
Howard Hinnant2347d2f2011-09-28 15:44:39 +0000[diff] [blame]121 <p>
Howard Hinnante1a0abb2012-07-31 21:30:28 +0000[diff] [blame]122 Ports to other platforms are underway. Here are recent test
123 results for <a href="results.Windows.html">Windows</a>
124 and <a href="results.Linux.html">Linux</a>.
Howard Hinnant2347d2f2011-09-28 15:44:39 +0000[diff] [blame]125 </p>
126
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]127 <!--=====================================================================-->
128 <h2>Get it and get involved!</h2>
129 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]130
Howard Hinnantf0721aa2011-09-30 16:58:02 +0000[diff] [blame]131 <p>First please review our
132 <a href="http://llvm.org/docs/DeveloperPolicy.html">Developer's Policy</a>.
133
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]134 <p>To check out the code, use:</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]135
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]136 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]137 <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]138 </ul>
139
Howard Hinnantbec2fd52011-11-17 17:14:16 +0000[diff] [blame]140 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]141 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]142 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]143 (getting the bleeding edge), read on. However, be warned that Mac OS
144 10.7 will not boot without a valid copy of <code>libc++.1.dylib</code> in
145 <code>/usr/lib</code>.
Howard Hinnantbec2fd52011-11-17 17:14:16 +0000[diff] [blame]146 </p>
147
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]148 <p>
149 Next:
150 </p>
151
152 <ul>
153 <li><code>cd libcxx/lib</code></li>
154 <li><code>export TRIPLE=-apple-</code></li>
155 <li><code>./buildit</code></li>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]156 <li><code>ln -sf libc++.1.dylib libc++.dylib</code></li>
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]157 </ul>
158
159 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]160 That should result in a libc++.1.dylib and libc++.dylib. The safest thing
161 to do is to use it from where your libcxx is installed instead of replacing
162 these in your Mac OS.
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]163 </p>
164
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]165 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]166 To use your system-installed libc++ with clang you can:
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]167 </p>
168
169 <ul>
170 <li><code>clang++ -stdlib=libc++ test.cpp</code></li>
Howard Hinnantd04724c2012-07-19 15:57:51 +0000[diff] [blame]171 <li><code>clang++ -std=c++11 -stdlib=libc++ test.cpp</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]172 </ul>
173
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]174 <p>
175 To use your tip-of-trunk libc++ on Mac OS with clang you can:
176 </p>
177
178 <ul>
179 <li><code>export DYLD_LIBRARY_PATH=&lt;path-to-libcxx&gt;/lib</code>
180 <li><code>clang++ -std=c++11 -stdlib=libc++ -nostdinc++
181 -I&lt;path-to-libcxx&gt;/include -L&lt;path-to-libcxx&gt;/lib
182 test.cpp</code></li>
183 </ul>
184
Marshall Clowbd02bde2012-08-22 00:57:11 +0000[diff] [blame]185 <p>To run the libc++ test suite (recommended):</p>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]186
187 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]188 <li><code>cd libcxx/test</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]189 <li><code>./testit</code></li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]190 <ul>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]191 <li>You can alter the command line options <code>testit</code> uses
192 with <code>export OPTIONS="whatever you need"</code></li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]193 </ul>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]194 </ul>
195
Howard Hinnant24147cf2012-05-20 13:03:53 +0000[diff] [blame]196 <!--=====================================================================-->
197 <h3>Notes</h3>
198 <!--=====================================================================-->
199
200<p>
201Building libc++ with <code>-fno-rtti</code> is not supported. However linking
202against it with <code>-fno-rtti</code> is supported.
203</p>
204
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]205 <p>Send discussions to the
Howard Hinnantc5b02f22010-05-11 19:53:34 +0000[diff] [blame]206 (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p>
207
Howard Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]208 <!--=====================================================================-->
Michael J. Spencera86f97e2012-12-31 19:34:21 +0000[diff] [blame]209 <h2>Build on Linux using CMake and libsupc++.</h2>
210 <!--=====================================================================-->
211
212 <p>
213 You will need libstdc++ in order to provide libsupc++.
214 </p>
215
216 <p>
217 Figure out where the libsupc++ headers are on your system. On Ubuntu this
218 is <code>/usr/include/c++/&lt;version&gt;</code> and
219 <code>/usr/include/c++/&lt;version&gt;/&lt;target-triple&gt;</code>
220 </p>
221
222 <p>
223 You can also figure this out by running
224 <pre>
225$ echo | g++ -Wp,-v -x c++ - -fsyntax-only
226ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
227ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.7/../../../../x86_64-linux-gnu/include"
228#include "..." search starts here:
229#include &lt;...&gt; search starts here:
230 /usr/include/c++/4.7
231 /usr/include/c++/4.7/x86_64-linux-gnu
232 /usr/include/c++/4.7/backward
233 /usr/lib/gcc/x86_64-linux-gnu/4.7/include
234 /usr/local/include
235 /usr/lib/gcc/x86_64-linux-gnu/4.7/include-fixed
236 /usr/include/x86_64-linux-gnu
237 /usr/include
238End of search list.
239 </pre>
240
241 Note the first two entries happen to be what we are looking for. This
242 may not be correct on other platforms.
243 </p>
244
245 <p>
246 We can now run CMake:
247 <ul>
248 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
249 -DLIBCXX_CXX_ABI=libsupc++
250 -DLIBCXX_LIBSUPCXX_INCLUDE_PATHS="/usr/include/c++/4.7/;/usr/include/c++/4.7/x86_64-linux-gnu/"
251 -DCMAKE_BUILD_TYPE=Release
252 -DCMAKE_INSTALL_PREFIX=/usr
253 &lt;libc++-source-dir&gt;</code></li>
254 <li><code>make</code></li>
255 <li><code>sudo make install</code></li>
256 </ul>
257 <p>
258 You can now run clang with -stdlib=libc++.
259 </p>
260 </p>
261
262 <!--=====================================================================-->
Howard Hinnant8d3824d2013-02-08 19:10:36 +0000[diff] [blame]263 <h2>Build on Linux using CMake and libc++abi.</h2>
264 <!--=====================================================================-->
265
266 <p>
267 You will need to keep the source tree of <a href="http://libcxxabi.llvm.org">libc++abi</a>
268 available on your build machine and your copy of the libc++abi shared library must
269 be placed where your linker will find it.
270 </p>
271
272 <p>
273 We can now run CMake:
274 <ul>
275 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
276 -DLIBCXX_CXX_ABI=libcxxabi
277 -DLIBCXX_LIBCXXABI_INCLUDE_PATHS="&lt;libc++abi-source-dir&gt;/include"
278 -DCMAKE_BUILD_TYPE=Release
279 -DCMAKE_INSTALL_PREFIX=/usr
280 &lt;libc++-source-dir&gt;</code></li>
281 <li><code>make</code></li>
282 <li><code>sudo make install</code></li>
283 </ul>
284 <p>
285 Unfortunately you can't simply run clang with "-stdlib=libc++" at this point, as
286 clang is set up to link for libc++ linked to libsupc++. To get around this
287 you'll have to set up your linker yourself (or patch clang). For example,
288 <ul>
289 <li><code>clang++ -stdlib=libc++ helloworld.cpp -nodefaultlibs -lc++ -lc++abi -lm -lc -lgcc_s -lgcc</code></li>
290 </ul>
291 Alternately, you could just add libc++abi to your libraries list, which in most
292 situations will give the same result:
293 <ul>
294 <li><code>clang++ -stdlib=libc++ helloworld.cpp -lc++abi</code></li>
295 </ul>
296 </p>
297 </p>
298
299 <!--=====================================================================-->
300 <h2>Build on Linux using CMake and libcxxrt.</h2>
301 <!--=====================================================================-->
302
303 <p>
304 You will need to keep the source tree of
305 <a href="https://github.com/pathscale/libcxxrt/">libcxxrt</a> available
306 on your build machine and your copy of the libcxxrt shared library must
307 be placed where your linker will find it.
308 </p>
309
310 <p>
311 We can now run CMake:
312 <ul>
313 <li><code>CC=clang CXX=clang++ cmake -G "Unix Makefiles"
314 -DLIBCXX_CXX_ABI=libcxxrt
Howard Hinnant727ff912013-02-26 16:27:55 +0000[diff] [blame]315 -DLIBCXX_LIBCXXRT_INCLUDE_PATHS="&lt;libcxxrt-source-dir&gt;/src"
Howard Hinnant8d3824d2013-02-08 19:10:36 +0000[diff] [blame]316 -DCMAKE_BUILD_TYPE=Release
317 -DCMAKE_INSTALL_PREFIX=/usr
318 &lt;libc++-source-dir&gt;</code></li>
319 <li><code>make</code></li>
320 <li><code>sudo make install</code></li>
321 </ul>
322 <p>
323 Unfortunately you can't simply run clang with "-stdlib=libc++" at this point, as
324 clang is set up to link for libc++ linked to libsupc++. To get around this
325 you'll have to set up your linker yourself (or patch clang). For example,
326 <ul>
327 <li><code>clang++ -stdlib=libc++ helloworld.cpp -nodefaultlibs -lc++ -lcxxrt -lm -lc -lgcc_s -lgcc</code></li>
328 </ul>
329 Alternately, you could just add libcxxrt to your libraries list, which in most
330 situations will give the same result:
331 <ul>
332 <li><code>clang++ -stdlib=libc++ helloworld.cpp -lcxxrt</code></li>
333 </ul>
334 </p>
335 </p>
336
337 <!--=====================================================================-->
Howard Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]338 <h2>Design Documents</h2>
339 <!--=====================================================================-->
340
341<ul>
342<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
Howard Hinnante20b8de2010-11-19 01:38:58 +0000[diff] [blame]343<li><a href="type_traits_design.html"><tt>&lt;type_traits&gt;</tt></a></li>
Howard Hinnanta26b3b52012-07-06 00:39:38 +0000[diff] [blame]344<li><a href="http://marshall.calepin.co/llvmclang-and-standard-libraries-on-mac-os-x.html">Excellent notes by Marshall Clow</a></li>
Howard Hinnant57724c32013-03-14 18:37:48 +0000[diff] [blame^]345<li><a href="debug_mode.html">Status of debug mode</a></li>
Howard Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]346</ul>
347
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]348</div>
349</body>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]350</html>