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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>
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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>
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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 <!--=====================================================================-->
Chris Lattner24173b82010-05-12 22:21:15 +0000[diff] [blame]60 <h2 id="why">Why a new C++ Standard Library for C++'0x?</h2>
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
Chris Lattnera5058d92010-05-12 22:30:22 +0000[diff] [blame]75 machines (particularly in C++'0x, which has rvalue references). Breaking
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
82 independently extended to support C++'0x, 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
90 candidates, but both lack C++'0x 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 Hinnantd0e811a2010-05-13 20:10:39 +0000[diff] [blame]118 <p><a href="libcxx_by_chapter.pdf">Here</a> is a by-chapter breakdown of what
119 is passing tests and what isn't. This chart is currently based on testing
Howard Hinnant30055c62012-07-30 02:29:34 +0000[diff] [blame]120 against clang++ with -std=c++11 on Apple's OS X. </p>
Howard Hinnantd0e811a2010-05-13 20:10:39 +0000[diff] [blame]121
Howard Hinnant0cbb3a12011-09-28 15:44:39 +0000[diff] [blame]122 <p>
Howard Hinnantee7a0bf2012-07-31 21:30:28 +0000[diff] [blame]123 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 Hinnant0cbb3a12011-09-28 15:44:39 +0000[diff] [blame]126 </p>
127
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]128 <!--=====================================================================-->
129 <h2>Get it and get involved!</h2>
130 <!--=====================================================================-->
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]131
Howard Hinnant2481cba2011-09-30 16:58:02 +0000[diff] [blame]132 <p>First please review our
133 <a href="http://llvm.org/docs/DeveloperPolicy.html">Developer's Policy</a>.
134
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]135 <p>To check out the code, use:</p>
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]136
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]137 <ul>
Chris Lattner4b748952010-05-11 20:37:52 +0000[diff] [blame]138 <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]139 </ul>
140
Howard Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]141 <p>
142 On Mac OS 10.7 (Lion), the easiest way to get this library is to install
143 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]144 (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 Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]147 </p>
148
149 <p>To build on Mac OS X 10.6 (Snow Leopard), you need a helper library and header
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]150 <a href="http://home.roadrunner.com/~hinnant/libcppabi.zip">found here</a>.
Howard Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]151 cp cxxabi.h to /usr/include, and cp libc++abi.dylib to /usr/lib. On Mac OS
152 X 10.7 (Lion) and later, this helper library and header are already installed
153 for you.
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]154 <p>
155
156 <p>
157 Next:
158 </p>
159
160 <ul>
161 <li><code>cd libcxx/lib</code></li>
162 <li><code>export TRIPLE=-apple-</code></li>
Howard Hinnant704f09b2011-11-17 17:14:16 +0000[diff] [blame]163 <li>Only on 10.6: <code>export MACOSX_DEPLOYMENT_TARGET=10.6</code></li>
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]164 <li><code>./buildit</code></li>
165 </ul>
166
167 <p>
168 That should result in a libc++.1.dylib. To install it I like to use links
169 instead of copying, but either should work:
170 </p>
171
172 <ul>
173 <li><code>cd /usr/lib</code></li>
Howard Hinnant5a245db2011-02-22 14:18:34 +0000[diff] [blame]174 <li><code>sudo ln -sf path-to-libcxx/lib/libc++.1.dylib libc++.1.dylib</code></li>
175 <li><code>sudo ln -sf libc++.1.dylib libc++.dylib</code></li>
Howard Hinnant65451f12011-01-27 23:18:19 +0000[diff] [blame]176 <li><code>cd /usr/include/c++</code></li>
177 <li><code>sudo ln -sf path-to-libcxx/include v1</code></li>
178 </ul>
179
180 <p>
181 To use with clang you can:
182 </p>
183
184 <ul>
185 <li><code>clang++ -stdlib=libc++ test.cpp</code></li>
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]186 <li><code>clang++ -std=c++11 -stdlib=libc++ test.cpp</code></li>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]187 </ul>
188
Marshall Clow08a0b482012-08-22 00:57:11 +0000[diff] [blame^]189 <p>To run the libc++ test suite (recommended):</p>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]190
191 <ul>
Chris Lattner4b748952010-05-11 20:37:52 +0000[diff] [blame]192 <li><code>cd libcxx/test</code></li>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]193 <li><code>./testit</code></li>
Howard Hinnantf5d76a72011-06-22 12:13:55 +0000[diff] [blame]194 <ul>
Howard Hinnant8b3fae32011-09-12 14:15:45 +0000[diff] [blame]195 <li>On Mac OS 10.6, to work around bugs in libc headers like
196 math.h and inttypes.h, add "-U__STRICT_ANSI__" and
197 "-D__STDC_FORMAT_MACROS" to the command line with:
198 <blockquote>
Howard Hinnantaf347342012-07-19 15:57:51 +0000[diff] [blame]199 <pre>export OPTIONS="-std=c++11 -stdlib=libc++ -U__STRICT_ANSI__ -D__STDC_FORMAT_MACROS"</pre>
Howard Hinnant8b3fae32011-09-12 14:15:45 +0000[diff] [blame]200 </blockquote></li>
201 <li>People porting libc++ to other OSes will likely have to
202 define similar macros.</li>
Howard Hinnantf5d76a72011-06-22 12:13:55 +0000[diff] [blame]203 </ul>
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]204 </ul>
205
Howard Hinnant51065652012-05-20 13:03:53 +0000[diff] [blame]206 <!--=====================================================================-->
207 <h3>Notes</h3>
208 <!--=====================================================================-->
209
210<p>
211Building libc++ with <code>-fno-rtti</code> is not supported. However linking
212against it with <code>-fno-rtti</code> is supported.
213</p>
214
Howard Hinnantd2bb0322010-08-22 01:04:38 +0000[diff] [blame]215 <p>Send discussions to the
Howard Hinnant8c217372010-05-11 19:53:34 +0000[diff] [blame]216 (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p>
217
Howard Hinnant56f0d5b2010-10-05 16:44:40 +0000[diff] [blame]218 <!--=====================================================================-->
219 <h2>Design Documents</h2>
220 <!--=====================================================================-->
221
222<ul>
223<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
Howard Hinnant9835d762010-11-19 01:38:58 +0000[diff] [blame]224<li><a href="type_traits_design.html"><tt>&lt;type_traits&gt;</tt></a></li>
Howard Hinnant820e0072012-07-06 00:39:38 +0000[diff] [blame]225<li><a href="http://marshall.calepin.co/llvmclang-and-standard-libraries-on-mac-os-x.html">Excellent notes by Marshall Clow</a></li>
Howard Hinnant56f0d5b2010-10-05 16:44:40 +0000[diff] [blame]226</ul>
227
Howard Hinnantbc8d3f92010-05-11 19:42:16 +0000[diff] [blame]228</div>
229</body>
Chris Lattner4b748952010-05-11 20:37:52 +0000[diff] [blame]230</html>