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 <h1>Clang 3.2 Release Notes</h1>

 <img style="float:right" src="http://llvm.org/img/DragonSmall.png"
      width="136" height="136" alt="LLVM Dragon Logo">

 <ul>
   <li><a href="#intro">Introduction</a></li>
   <li><a href="#whatsnew">What's New in Clang 3.2?</a>
     <ul>
       <li><a href="#majorfeatures">Major New Features</a></li>
       <li><a href="#newflags">New Compiler Flags</a></li>
       <li><a href="#cchanges">C Language Changes</a></li>
       <li><a href="#cxxchanges">C++ Language Changes</a></li>
       <li><a href="#objcchanges">Objective-C Language Changes</a></li>
       <li><a href="#apichanges">Internal API Changes</a></li>
       <li><a href="#pythonchanges">Python Binding Changes</a></li>
     </ul>
   </li>
   <li><a href="#knownproblems">Known Problems</a></li>
   <li><a href="#additionalinfo">Additional Information</a></li>
 </ul>

 <div class="doc_author">
   <p>Written by the <a href="http://llvm.org/">LLVM Team</a></p>
 </div>

 <h1 style="color:red">These are in-progress notes for the upcoming Clang 3.2
 release.<br>
 You may prefer the
 <a href="http://llvm.org/releases/3.1/docs/ClangReleaseNotes.html">Clang 3.1
 Release Notes</a>.</h1>

 <!-- ======================================================================= -->
 <h2 id="intro">Introduction</h2>
 <!-- ======================================================================= -->

 <p>This document contains the release notes for the Clang C/C++/Objective-C
    frontend, part of the LLVM Compiler Infrastructure, release 3.2.  Here we
    describe the status of Clang in some detail, including major improvements
    from the previous release and new feature work. For the general LLVM release
    notes, see <a href="http://llvm.org/docs/ReleaseNotes.html">the LLVM
    documentation</a>. All LLVM releases may be downloaded from the
    <a href="http://llvm.org/releases/">LLVM releases web site</a>.</p>

 <p>For more information about Clang or LLVM, including information about the
    latest release, please check out the main please see the
    <a href="http://clang.llvm.org">Clang Web Site</a> or the
    <a href="http://llvm.org">LLVM Web Site</a>.

 <p>Note that if you are reading this file from a Subversion checkout or the main
    Clang web page, this document applies to the <i>next</i> release, not the
    current one.  To see the release notes for a specific release, please see the
    <a href="http://llvm.org/releases/">releases page</a>.</p>

 <!-- ======================================================================= -->
 <h2 id="whatsnew">What's New in Clang 3.2?</h2>
 <!-- ======================================================================= -->

 <p>Some of the major new features and improvements to Clang are listed here.
   Generic improvements to Clang as a whole or to its underlying infrastructure
   are described first, followed by language-specific sections with improvements
   to Clang's support for those languages.</p>

 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="majorfeatures">Major New Features</h3>
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

 <h4 id="diagnostics">Improvements to Clang's diagnostics</h4>

 <p>Clang's diagnostics are constantly being improved to catch more issues,
 explain them more clearly, and provide more accurate source information about
 them. The improvements since the 3.1 release include:</p>

 <ul>
   <li><tt>-Wuninitialized</tt> has been taught to recognise uninitialized uses
   which always occur when an explicitly-written non-constant condition is either
   <tt>true</tt> or <tt>false</tt>. For example:

 <pre>
 int f(bool b) {
   int n;
   if (b)
     n = 1;
   return n;
 }

 <b>sometimes-uninit.cpp:3:7: <span class="warning">warning:</span> variable 'n' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]</b>
   if (b)
       <span class="caret">^</span>
 <b>sometimes-uninit.cpp:5:10: <span class="note">note:</span></b> uninitialized use occurs here
   return n;
          <span class="caret">^</span>
 <b>sometimes-uninit.cpp:3:3: <span class="note">note:</span></b> remove the 'if' if its condition is always true
   if (b)
   <span class="caret">^~~~~~</span>
 <b>sometimes-uninit.cpp:2:8: <span class="note">note:</span></b> initialize the variable 'n' to silence this warning
   int n;
        <span class="caret">^</span>
        <span class="caret"> = 0</span>
 </pre>

   This functionality can be enabled or disabled separately from
   <tt>-Wuninitialized</tt> with the <tt>-Wsometimes-uninitialized</tt> warning
   flag.</li>
 </ul>

 <h4 id="tlsmodel">Support for <code>tls_model</code> attribute</h4>

 <p>Clang now supports the <code>tls_model</code> attribute, allowing code that
 uses thread-local storage to explicitly select which model to use. The available
 models are <code>"global-dynamic"</code>, <code>"local-dynamic"</code>,
 <code>"initial-exec"</code> and <code>"local-exec"</code>. See
 <a href="http://www.akkadia.org/drepper/tls.pdf">ELF Handling For Thread-Local
  Storage</a> for more information.</p>

 <p>The compiler is free to choose a different model if the specified model is not
 supported by the target, or if the compiler determines that a more specific
 model can be used.
 </p>

 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="newflags">New Compiler Flags</h3>
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <ul>
   <li><tt>-gline-tables-only</tt> controls the
   <a href="http://clang.llvm.org/docs/UsersManual.html#debuginfosize">size of debug information</a>.
   This flag tells Clang to emit debug info which is just enough to obtain stack traces with
   function names, file names and line numbers (by such tools as gdb or addr2line).
   Debug info for variables or function parameters is not produced, which reduces
   the size of the resulting binary.
 </ul>

 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="cchanges">C Language Changes in Clang</h3>
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

 <h4 id="c11changes">C11 Feature Support</h4>

 <p>...</p>

 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="cxxchanges">C++ Language Changes in Clang</h3>
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

 <h4 id="cxx11changes">C++11 Feature Support</h4>

 <p>...</p>

 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="objcchanges">Objective-C Language Changes in Clang</h3>
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

 <p>...</p>

 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="apichanges">Internal API Changes</h3>
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

 <p>These are major API changes that have happened since the 3.1 release of
    Clang. If upgrading an external codebase that uses Clang as a library, this
    section should help get you past the largest hurdles of upgrading.</p>

 <h4 id="api1">API change 1</h4>

 <p>...</p>

 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="pythonchanges">Python Binding Changes</h3>
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

 The following methods have been added:
 <ul>
   <li>...</li>
 </ul>

 <!-- ======================================================================= -->
 <h2 id="knownproblems">Significant Known Problems</h2>
 <!-- ======================================================================= -->

 <!-- ======================================================================= -->
 <h2 id="additionalinfo">Additional Information</h2>
 <!-- ======================================================================= -->

 <p>A wide variety of additional information is available on the
    <a href="http://clang.llvm.org/">Clang web page</a>.  The web page contains
    versions of the API documentation which are up-to-date with the Subversion
    version of the source code.  You can access versions of these documents
    specific to this release by going into the "<tt>clang/doc/</tt>" directory in
    the Clang tree.</p>

 <p>If you have any questions or comments about Clang, please feel free to
    contact us via
    the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev"> mailing
    list</a>.</p>

 <!-- ======================================================================= -->
 <!-- Likely 3.1 release notes -->
 <!-- ======================================================================= -->
 <!--
 This is just a section to hold things that have already gotten started and
 should likely pick up proper release notes in 3.1.

 - C1X and C++11 atomics infrastructure and support
 - CUDA support?

 -->

 </div>
 </body>
 </html>
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	<title>Clang 3.2 Release Notes</title>
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	<link type="text/css" rel="stylesheet" href="../content.css">
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	td {
	vertical-align: top;
	}
	</style>
	</head>
	<body>

	<!--#include virtual="../menu.html.incl"-->

	<div id="content">

	<h1>Clang 3.2 Release Notes</h1>

	<img style="float:right" src="http://llvm.org/img/DragonSmall.png"
	width="136" height="136" alt="LLVM Dragon Logo">

	<ul>
	<li><a href="#intro">Introduction</a></li>
	<li><a href="#whatsnew">What's New in Clang 3.2?</a>
	<ul>
	<li><a href="#majorfeatures">Major New Features</a></li>
	<li><a href="#newflags">New Compiler Flags</a></li>
	<li><a href="#cchanges">C Language Changes</a></li>
	<li><a href="#cxxchanges">C++ Language Changes</a></li>
	<li><a href="#objcchanges">Objective-C Language Changes</a></li>
	<li><a href="#apichanges">Internal API Changes</a></li>
	<li><a href="#pythonchanges">Python Binding Changes</a></li>
	</ul>
	</li>
	<li><a href="#knownproblems">Known Problems</a></li>
	<li><a href="#additionalinfo">Additional Information</a></li>
	</ul>

	<div class="doc_author">
	<p>Written by the <a href="http://llvm.org/">LLVM Team</a></p>
	</div>

	<h1 style="color:red">These are in-progress notes for the upcoming Clang 3.2
	release.<br>
	You may prefer the
	<a href="http://llvm.org/releases/3.1/docs/ClangReleaseNotes.html">Clang 3.1
	Release Notes</a>.</h1>

	<!-- ======================================================================= -->
	<h2 id="intro">Introduction</h2>
	<!-- ======================================================================= -->

	<p>This document contains the release notes for the Clang C/C++/Objective-C
	frontend, part of the LLVM Compiler Infrastructure, release 3.2. Here we
	describe the status of Clang in some detail, including major improvements
	from the previous release and new feature work. For the general LLVM release
	notes, see <a href="http://llvm.org/docs/ReleaseNotes.html">the LLVM
	documentation</a>. All LLVM releases may be downloaded from the
	<a href="http://llvm.org/releases/">LLVM releases web site</a>.</p>

	<p>For more information about Clang or LLVM, including information about the
	latest release, please check out the main please see the
	<a href="http://clang.llvm.org">Clang Web Site</a> or the
	<a href="http://llvm.org">LLVM Web Site</a>.

	<p>Note that if you are reading this file from a Subversion checkout or the main
	Clang web page, this document applies to the <i>next</i> release, not the
	current one. To see the release notes for a specific release, please see the
	<a href="http://llvm.org/releases/">releases page</a>.</p>

	<!-- ======================================================================= -->
	<h2 id="whatsnew">What's New in Clang 3.2?</h2>
	<!-- ======================================================================= -->

	<p>Some of the major new features and improvements to Clang are listed here.
	Generic improvements to Clang as a whole or to its underlying infrastructure
	are described first, followed by language-specific sections with improvements
	to Clang's support for those languages.</p>

	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	<h3 id="majorfeatures">Major New Features</h3>
	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

	<h4 id="diagnostics">Improvements to Clang's diagnostics</h4>

	<p>Clang's diagnostics are constantly being improved to catch more issues,
	explain them more clearly, and provide more accurate source information about
	them. The improvements since the 3.1 release include:</p>

	<ul>
	<li><tt>-Wuninitialized</tt> has been taught to recognise uninitialized uses
	which always occur when an explicitly-written non-constant condition is either
	<tt>true</tt> or <tt>false</tt>. For example:

	<pre>
	int f(bool b) {
	int n;
	if (b)
	n = 1;
	return n;
	}

	<b>sometimes-uninit.cpp:3:7: <span class="warning">warning:</span> variable 'n' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]</b>
	if (b)
	<span class="caret">^</span>
	<b>sometimes-uninit.cpp:5:10: <span class="note">note:</span></b> uninitialized use occurs here
	return n;
	<span class="caret">^</span>
	<b>sometimes-uninit.cpp:3:3: <span class="note">note:</span></b> remove the 'if' if its condition is always true
	if (b)
	<span class="caret">^~~~~~</span>
	<b>sometimes-uninit.cpp:2:8: <span class="note">note:</span></b> initialize the variable 'n' to silence this warning
	int n;
	<span class="caret">^</span>
	<span class="caret"> = 0</span>
	</pre>

	This functionality can be enabled or disabled separately from
	<tt>-Wuninitialized</tt> with the <tt>-Wsometimes-uninitialized</tt> warning
	flag.</li>
	</ul>

	<h4 id="tlsmodel">Support for <code>tls_model</code> attribute</h4>

	<p>Clang now supports the <code>tls_model</code> attribute, allowing code that
	uses thread-local storage to explicitly select which model to use. The available
	models are <code>"global-dynamic"</code>, <code>"local-dynamic"</code>,
	<code>"initial-exec"</code> and <code>"local-exec"</code>. See
	<a href="http://www.akkadia.org/drepper/tls.pdf">ELF Handling For Thread-Local
	Storage</a> for more information.</p>

	<p>The compiler is free to choose a different model if the specified model is not
	supported by the target, or if the compiler determines that a more specific
	model can be used.
	</p>

	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	<h3 id="newflags">New Compiler Flags</h3>
	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	<ul>
	<li><tt>-gline-tables-only</tt> controls the
	<a href="http://clang.llvm.org/docs/UsersManual.html#debuginfosize">size of debug information</a>.
	This flag tells Clang to emit debug info which is just enough to obtain stack traces with
	function names, file names and line numbers (by such tools as gdb or addr2line).
	Debug info for variables or function parameters is not produced, which reduces
	the size of the resulting binary.
	</ul>

	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	<h3 id="cchanges">C Language Changes in Clang</h3>
	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

	<h4 id="c11changes">C11 Feature Support</h4>

	<p>...</p>

	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	<h3 id="cxxchanges">C++ Language Changes in Clang</h3>
	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

	<h4 id="cxx11changes">C++11 Feature Support</h4>

	<p>...</p>

	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	<h3 id="objcchanges">Objective-C Language Changes in Clang</h3>
	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

	<p>...</p>

	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	<h3 id="apichanges">Internal API Changes</h3>
	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

	<p>These are major API changes that have happened since the 3.1 release of
	Clang. If upgrading an external codebase that uses Clang as a library, this
	section should help get you past the largest hurdles of upgrading.</p>

	<h4 id="api1">API change 1</h4>

	<p>...</p>

	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	<h3 id="pythonchanges">Python Binding Changes</h3>
	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->

	The following methods have been added:
	<ul>
	<li>...</li>
	</ul>

	<!-- ======================================================================= -->
	<h2 id="knownproblems">Significant Known Problems</h2>
	<!-- ======================================================================= -->

	<!-- ======================================================================= -->
	<h2 id="additionalinfo">Additional Information</h2>
	<!-- ======================================================================= -->

	<p>A wide variety of additional information is available on the
	<a href="http://clang.llvm.org/">Clang web page</a>. The web page contains
	versions of the API documentation which are up-to-date with the Subversion
	version of the source code. You can access versions of these documents
	specific to this release by going into the "<tt>clang/doc/</tt>" directory in
	the Clang tree.</p>

	<p>If you have any questions or comments about Clang, please feel free to
	contact us via
	the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev"> mailing
	list</a>.</p>

	<!-- ======================================================================= -->
	<!-- Likely 3.1 release notes -->
	<!-- ======================================================================= -->
	<!--
	This is just a section to hold things that have already gotten started and
	should likely pick up proper release notes in 3.1.

	- C1X and C++11 atomics infrastructure and support
	- CUDA support?

	-->

	</div>
	</body>
	</html>