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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 <!--=====================================================================-->
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>
Howard Hinnant075ac852010-05-13 20:10:39 +0000[diff] [blame]119
Howard Hinnant2347d2f2011-09-28 15:44:39 +0000[diff] [blame]120 <p>
Howard Hinnante1a0abb2012-07-31 21:30:28 +0000[diff] [blame]121 Ports to other platforms are underway. Here are recent test
122 results for <a href="results.Windows.html">Windows</a>
123 and <a href="results.Linux.html">Linux</a>.
Howard Hinnant2347d2f2011-09-28 15:44:39 +0000[diff] [blame]124 </p>
125
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]126 <!--=====================================================================-->
127 <h2>Get it and get involved!</h2>
128 <!--=====================================================================-->
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]129
Howard Hinnantf0721aa2011-09-30 16:58:02 +0000[diff] [blame]130 <p>First please review our
131 <a href="http://llvm.org/docs/DeveloperPolicy.html">Developer's Policy</a>.
132
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]133 <p>To check out the code, use:</p>
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]134
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]135 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]136 <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]137 </ul>
138
Howard Hinnantbec2fd52011-11-17 17:14:16 +0000[diff] [blame]139 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]140 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]141 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]142 (getting the bleeding edge), read on. However, be warned that Mac OS
143 10.7 will not boot without a valid copy of <code>libc++.1.dylib</code> in
144 <code>/usr/lib</code>.
Howard Hinnantbec2fd52011-11-17 17:14:16 +0000[diff] [blame]145 </p>
146
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]147 <p>
148 Next:
149 </p>
150
151 <ul>
152 <li><code>cd libcxx/lib</code></li>
153 <li><code>export TRIPLE=-apple-</code></li>
154 <li><code>./buildit</code></li>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]155 <li><code>ln -sf libc++.1.dylib libc++.dylib</code></li>
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]156 </ul>
157
158 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]159 That should result in a libc++.1.dylib and libc++.dylib. The safest thing
160 to do is to use it from where your libcxx is installed instead of replacing
161 these in your Mac OS.
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]162 </p>
163
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]164 <p>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]165 To use your system-installed libc++ with clang you can:
Howard Hinnantefc7aa22011-01-27 23:18:19 +0000[diff] [blame]166 </p>
167
168 <ul>
169 <li><code>clang++ -stdlib=libc++ test.cpp</code></li>
Howard Hinnantd04724c2012-07-19 15:57:51 +0000[diff] [blame]170 <li><code>clang++ -std=c++11 -stdlib=libc++ test.cpp</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]171 </ul>
172
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]173 <p>
174 To use your tip-of-trunk libc++ on Mac OS with clang you can:
175 </p>
176
177 <ul>
178 <li><code>export DYLD_LIBRARY_PATH=&lt;path-to-libcxx&gt;/lib</code>
179 <li><code>clang++ -std=c++11 -stdlib=libc++ -nostdinc++
180 -I&lt;path-to-libcxx&gt;/include -L&lt;path-to-libcxx&gt;/lib
181 test.cpp</code></li>
182 </ul>
183
Marshall Clowbd02bde2012-08-22 00:57:11 +0000[diff] [blame]184 <p>To run the libc++ test suite (recommended):</p>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]185
186 <ul>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]187 <li><code>cd libcxx/test</code></li>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]188 <li><code>./testit</code></li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]189 <ul>
Howard Hinnant79d6bcc2012-11-06 21:31:37 +0000[diff] [blame]190 <li>You can alter the command line options <code>testit</code> uses
191 with <code>export OPTIONS="whatever you need"</code></li>
Howard Hinnant14c2a082011-06-22 12:13:55 +0000[diff] [blame]192 </ul>
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]193 </ul>
194
Howard Hinnant24147cf2012-05-20 13:03:53 +0000[diff] [blame]195 <!--=====================================================================-->
196 <h3>Notes</h3>
197 <!--=====================================================================-->
198
199<p>
200Building libc++ with <code>-fno-rtti</code> is not supported. However linking
201against it with <code>-fno-rtti</code> is supported.
202</p>
203
Howard Hinnant3e1b0422010-08-22 01:04:38 +0000[diff] [blame]204 <p>Send discussions to the
Howard Hinnantc5b02f22010-05-11 19:53:34 +0000[diff] [blame]205 (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p>
206
Howard Hinnantbded6c92010-10-05 16:44:40 +0000[diff] [blame]207 <!--=====================================================================-->
208 <h2>Design Documents</h2>
209 <!--=====================================================================-->
210
211<ul>
212<li><a href="atomic_design.html"><tt>&lt;atomic&gt;</tt></a></li>
Howard Hinnante20b8de2010-11-19 01:38:58 +0000[diff] [blame]213<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]214<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]215</ul>
216
Howard Hinnantc51e1022010-05-11 19:42:16 +0000[diff] [blame]217</div>
218</body>
Chris Lattnere66f1e32010-05-11 20:37:52 +0000[diff] [blame]219</html>