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19d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant    <label>libc++abi Info</label>
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24d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant    <label>Quick Links</label>
25d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant    <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">cfe-dev</a>
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27d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant    <a href="http://llvm.org/bugs/">Bug Reports</a>
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34d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--*********************************************************************-->
35d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <h1>"libc++abi" C++ Standard Library Support</h1>
36d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--*********************************************************************-->
37d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
38d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <p>libc++abi is a new implementation of low level support for a standard
39d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant     C++ library.</p>
40d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
41d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <p>All of the code in libc++abi is <a
42d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant     href="http://llvm.org/docs/DeveloperPolicy.html#license">dual licensed</a>
43d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant     under the MIT license and the UIUC License (a BSD-like license).</p>
44d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
45d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--=====================================================================-->
46d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <h2 id="goals">Features and Goals</h2>
47d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--=====================================================================-->
48d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
49d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant    <ul>
50d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant        <li>Correctness as defined by the C++11 standard.</li>
51f59526da20aa9e8606881a6dc064a3981e91ff37Sylvestre Ledru        <li>Provide a portable sublayer to ease the porting of <a href="http://libcxx.llvm.org/">libc++</a></li>
52628bfc461df5d87a8fbf7d10cce7325245fd7d7eHoward Hinnant        <li>On Mac OS X, be ABI compatible with the existing low-level support.</li>
53d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant    </ul>
54d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
55d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--=====================================================================-->
56d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <h2 id="requirements">Platform Support</h2>
57d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--=====================================================================-->
58d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
59d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant   <p>libc++abi is known to work on the following platforms, using clang.</p>
60d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
61d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant    <ul>
62de2b1090d44a81c97ff3f1c21fac6088a1e28465Howard Hinnant    <li>Darwin</li>
63d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant    </ul>
64d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
65d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--=====================================================================-->
66d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <h2 id="dir-structure">Current Status</h2>
67d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--=====================================================================-->
68d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
69de2b1090d44a81c97ff3f1c21fac6088a1e28465Howard Hinnant   <p>libc++abi is complete.  <a href="spec.html">Here</a> is a
70de2b1090d44a81c97ff3f1c21fac6088a1e28465Howard Hinnant   list of functionality.</p>
71d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
72d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--=====================================================================-->
73d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <h2>Get it and get involved!</h2>
74d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <!--=====================================================================-->
75d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
76d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <p>To check out the code, use:</p>
77d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
78d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <ul>
79d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <li><code>svn co http://llvm.org/svn/llvm-project/libcxxabi/trunk libcxxabi</code></li>
80d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  </ul>
81d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
82d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  <p>Send discussions to the
83d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant  (<a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">clang mailing list</a>).</p>
84d213ffdf3befead3b8f5a0ba12ce1c2d9949525Howard Hinnant
85e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert  <!--=====================================================================-->
86e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert  <h2>Frequently asked questions</h2>
87e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert  <!--=====================================================================-->
88e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert
89e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert  <p>Q: Why are the destructors for the standard exception classes defined in libc++abi?
90e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     They're just empty, can't they be defined inline?</p>
91e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert  <p>A: The destructors for them live in libc++abi because they are "key" functions.
92e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     The Itanium ABI describes a "key" function as the first virtual declared.
93e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     And wherever the key function is defined, that is where the <code>type_info</code> gets defined.
94e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     And in libc++ types are the same type if and only if they have the same <code>type_info</code>
95e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     (as in there must be only one type info per type in the entire application).
96e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     And on OS X, libstdc++ and libc++ share these exception types.
97e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     So to be able to throw in one dylib and catch in another (a <code>std::exception</code> for example), 
98e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     there must be only one <code>std::exception type_info</code> in the entire app.
99e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     That typeinfo gets laid down beside <code>~exception()</code> in libc++abi (for both libstdc++ and libc++).</p>
100e45805f0d3f8dafef1297cc7dc49e610713f023bDan Albert     <p>--Howard Hinnant</p>
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