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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>
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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>
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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 <!--=====================================================================-->
Chris Lattnere2b07272010-05-12 22:21:15 +0000[diff] [blame]60 <h2 id="why">Why a new C++ Standard Library for C++'0x?</h2>
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
Chris Lattnerc67061b2010-05-12 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 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
82 independently extended to support C++'0x, 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
90 candidates, but both lack C++'0x 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 Hinnant075ac852010-05-13 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 Hinnant11e9d5c2012-07-30 02:29:34 +0000[diff] [blame]120 against clang++ with -std=c++11 on Apple's OS X. </p>
Howard Hinnant075ac852010-05-13 20:10:39 +0000[diff] [blame]121
Howard Hinnant2347d2f2011-09-28 15:44:39 +0000[diff] [blame]122 <p>
Howard Hinnante1a0abb2012-07-31 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 Hinnant2347d2f2011-09-28 15:44:39 +0000[diff] [blame]126 </p>
127
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]128 <!--=====================================================================-->
129 <h2>Get it and get involved!</h2>
130 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]131
Howard Hinnantf0721aa2011-09-30 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 Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]135 <p>To check out the code, use:</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]136
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]137 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]138 <li><code>svn co http://llvm.org/svn/llvm-project/libcxx/trunk libcxx</code></li>
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]139 </ul>
140
Howard Hinnantbec2fd52011-11-17 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 Hinnant961a7352012-04-03 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 Hinnantbec2fd52011-11-17 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 Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]150 <a href="http://home.roadrunner.com/~hinnant/libcppabi.zip">found here</a>.
Howard Hinnantbec2fd52011-11-17 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 Hinnantefc7aa22011-01-27 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 Hinnantbec2fd52011-11-17 17:14:16 +0000[diff] [blame]163 <li>Only on 10.6: <code>export MACOSX_DEPLOYMENT_TARGET=10.6</code></li>
Howard Hinnantefc7aa22011-01-27 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 Hinnant38438dd2011-02-22 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 Hinnantefc7aa22011-01-27 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 Hinnantd04724c2012-07-19 15:57:51 +0000[diff] [blame]186 <li><code>clang++ -std=c++11 -stdlib=libc++ test.cpp</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]187 </ul>
188
189 <p>To run the libc++ test suit (recommended):</p>
190
191 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]192 <li><code>cd libcxx/test</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]193 <li><code>./testit</code></li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]194 <ul>
Howard Hinnanta42b3d02011-09-12 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 Hinnantd04724c2012-07-19 15:57:51 +0000[diff] [blame]199 <pre>export OPTIONS="-std=c++11 -stdlib=libc++ -U__STRICT_ANSI__ -D__STDC_FORMAT_MACROS"</pre>
Howard Hinnanta42b3d02011-09-12 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 Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]203 </ul>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]204 </ul>
205
Howard Hinnant24147cf2012-05-20 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 Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]215 <p>Send discussions to the
Howard Hinnantc5b02f22010-05-11 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 Hinnantbded6c92010-10-05 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 Hinnante20b8de2010-11-19 01:38:58 +0000[diff] [blame]224<li><a href="type_traits_design.html"><tt>&lt;type_traits&gt;</tt></a></li>
Howard Hinnanta26b3b52012-07-06 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 Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]226</ul>
227
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]228</div>
229</body>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]230</html>