docs/ReleaseNotes.html - clang - Git at Google

 <html>
 <head>
 <title>Clang 3.0 Release Notes</title>
 <link type="text/css" rel="stylesheet" href="../menu.css" />
 <link type="text/css" rel="stylesheet" href="../content.css" />
 <style type="text/css">
 td {
 	vertical-align: top;
 }
 </style>
 </head>
 <body>

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

 <div id="content">

 <h1>Clang 3.0 Release Notes</h1>

 <img align=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 3.0?</a>
     <ul>
       <li><a href="#majorfeatures">Major New Features</a></li>
       <li><a href="#cchanges">C Language Changes</a></li>
       <li><a href="#cxxhanges">C++ Language Changes</a></li>
       <li><a href="#objchanges">Objective-C Language Changes</a></li>
       <li><a href="#apichanges">Internal API 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 LLVM 3.0
 release.<br>
 You may prefer the
 <a href="http://llvm.org/releases/2.9/docs/ReleaseNotes.html">LLVM 2.9
 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 3.0.  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 3.0?</h2>
 <!-- ======================================================================= -->

 <p>Some of the major new features and improvements to Clang are listed here.
 Generic improvements to Clang as a whole or two 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">A multitude of improvements to Clang's diagnostics</h4>
 Clang's diagnostics are constantly being improved to catch more issues, explain
 them more clearly, and provide more accurate source information about them.
 A few improvements since the 2.9 release that have a particularly high impact:
 <ul>
   <li>Substantially shorter messages due to better recovery, fewer include
   stacks, and tuning verbose features such as 'a.k.a.' type printing.</li>
   <li>
     Able to recover and correct from misspelled type names at the beging of
     statements. For example, Clang now emits:
 <pre><b>t.c:6:3: <span class="error">error:</span> use of undeclared identifier 'integer'; did you mean 'Integer'?</b>
   integer *i = 0;
   <span class="caret">^~~~~~~</span>
   Integer
 <b>t.c:1:13: note:</b> 'Integer' declared here
 typedef int Integer;
             <span class="caret">^</span></pre>
   </li>
   <li>Expanded typo correction to (among other improvements) look across
   namespaces and suggest namespace qualifiers in addition to misspellings of the
   identifier itself.</li>
   <li>More rich macro expansion backtraces and some (limited) fix-it hints when
   diagnostics stem from macro arguments.</li>
   <li>Many new warnings have been added to catch common, bug-prone code
   patterns.</li>
   <li>Uninitialized values Clang warning was rewritten to be more accurate,
   faster, and able to differentiate between the <em>possibility</em> of an
   uninitialized use and the <em>certainty</em> of an uninitialized use.</li>
 </ul>

 <h4 id="libclang">This release saw significant improvements to <code>libclang</code></h4>
 <ul>
   <li>A broader set of the <code>libclang</code> API is exposed in the Python
   bindings.</li>
   <li>Much more of the Clang AST is exposed through <code>libclang</code>'s APIs
   and cursors.</li>
   <li>Cursors can now walk more effectively through macros, especially arguments
   to function-style macros, and resolve to the underlying AST.</li>
   <li>Improved code completion surrounding macros, macro arguments, and
   token pasting.</li>
   <li>Improved code completion for in-class member functions.</li>
   <li>Crash recovery for <code>libclang</code> clients.</li>
   <!-- Doug or Ted may want to flesh this out if there are relevant details I'm
   glossing over... -->
 </ul>

 <h4 id="driver">The Clang GCC-compatible command-line driver improved dramatically</h4>
 A great deal of work went into the GCC-compatible driver for the 3.0 release
 making it support more operating systems, emulate GCC behavior more accurately,
 and support a much broader range of Linux distributions out of the box.
 <ul>
   <li>More accurate support for hardware architecture pre-defined macros (e.g.,
   __i686__).</li>
   <li>Robust library and header search paths for the vast majority of x86 and
   x86-64 Linux distributions.</li>
   <li>Improved support for newer Darwin platforms.</li>
   <li>Partial support for <code>--sysroot=...</code> based cross-compiling on
   Linux (and similar) host systems.</li>
   <li>Improved support for locating and using libcxx when installed, especially
   on Darwin.</li>
   <!-- There are likely more Darwin-specific improvements to mention here? -->
   <!-- What support was added for FreeBSD? NetBSD? Anything noteworthy? -->
   <li>Automatic detection of Clang crashes in the driver and preparation of
   reproduction steps for filing bug reports.</li><!-- Chad, feel free to add
   more details here. -->
 </ul>

 <h4 id="ppcallbacks">Expanded support for instrumenting the preprocessor through
   callbacks</h4>
 Several enhancements were made to the <code>PPCallbacks</code> interface to
 expand the information available to tools and library users of Clang that wish
 to introspect the preprocessing.
 <ul>
   <li>The exact text used between the <code>""</code>s or <code>&lt;&gt;</code>s is reported.</li>
   <li>The header search path used to locate the header is reported.</li>
   <li>Missing files during including headers reported.</li>
   <li>The exact source range for expanded macros can be retrieved.</li>
 </ul>

 <h4 id="windows">Clang is building and tested regularly on Windows and can
   compile limited subsets of code on Windows</h4>
 Clang is regularly built and tested on a variety of Windows platforms including
 MinGW 32-bit and 64-bit, Cygwin, and natively with MSVC. In addition, Clang can
 be used as a compiler in a few Windows contexts.
 <ul>
   <li>Normal compilation supported for the MinGW target platform, in both 32-bit
   and 64-bit, and the Cygwin target platform.</li>
   <li>Parsing and AST support for Windows Structured Exception Handling.</li>
   <li>New -fms-compatibility flag to handle MSVC constructs that could change
   the meaning of an otherwise well formed program</li>
   <li>clang can now parse all the MSVC 2010 standard C++ header files
   in the nominal case, (still need to specifiy -nobuiltininc for some headers).</li>
   <li>Improved support for MFC code parsing, (still a work in progress).</li>
   <li>Add support for function template specialization at class scope (-fms-extensions mode).</li>
   <li>Add support for Microsoft __if_exists/__if_not_exists statements (-fms-extensions mode).</li>
 </ul>

 <h4 id="availability">New availability attribute to detect and warn about API
 usage across OS X and iOS versions</h4>
 Clang now supports an attribute which documents the availability of an API
 across various platforms and releases, allowing interfaces to include
 information about what OS versions support the relevant features. Based on the
 targeted version of a compile, warnings for deprecated and unavailable
 interfaces will automatically be provided by Clang.

 <h4 id="threadsafety">Thread Safety annotations and analysis-based warnings</h4>
 A set of annotations were introduced to Clang to describe the various
 thread-safety concerns of a program, and an accompanying set of analysis based
 warnings will diagnose clearly unsafe code patterns. The annotations are
 described in the
 <a href="http://clang.llvm.org/docs/LanguageExtensions.html#threadsafety">extension specification</a>,
 and the warnings currently supported include:
 <ul>
   <li>Calling functions without the required locks</li>
   <li>Reading variables without the required locks</li>
   <li>Writing to variables without an exclusive lock (even if holding a shared
   lock)</li>
   <li>Imbalance between locks and unlocks across loop entries and exits</li>
   <li>Acquiring or releasing locks out of order</li>
 </ul>

 <h4 id="incompleteast">Improved support for partially constructed and/or
 incomplete ASTs</h4>
 For users such as LLDB that are dynamically forming C++ ASTs, sometimes it is
 either necessary or useful to form a partial or incomplete AST. Support for
 these use cases have improved through the introduction of "unknown" types and
 other AST constructs designed specifically for use cases without complete
 information about the C++ construct being formed.

 <h4 id="opencl">Initial work to support compiling OpenCL C with Clang</h4>
 <p>Clang has some (limited) support for compiling OpenCL C.  The 3.0
 release adds support for the <tt>vec_step</tt> operator, address space
 qualifiers (<tt>__private</tt>, <tt>__global</tt>, <tt>__local</tt> and
 <tt>__constant</tt>), improved vector literal support and code generation
 support for the <a href="http://llvm.org/docs/ReleaseNotes.html#PTX">PTX
 target</a>.</p>

 <p>Using the <a href="http://www.pcc.me.uk/~peter/libclc/">libclc library</a>
 to supply OpenCL C built-ins, you can use Clang to compile OpenCL C code
 into PTX and execute it by loading the resulting PTX as a binary blob using
 the nVidia OpenCL library.  It has been tested with several OpenCL programs,
 including some from the nVidia GPU Computing SDK, and the performance is on
 par with the nVidia compiler.</p>

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

 <h4 id="c1xchanges">C1X Feature Support</h4>

 <p>Clang 3.0 adds support for the
 <a href="http://clang.llvm.org/docs/LanguageExtensions.html#c1x">
 <code>_Alignas</code>, <code>_Generic</code>, and <code>_Static_assert</code>
 keywords</a>, drafted for inclusion in the next C standard, which is
 provisionally known as C1X. Use <code>-std=c1x</code> or <code>-std=gnu1x</code>
 to enable support for the new language standard. These features are
 backwards-compatible and are available as an extension in all language
 modes.</p>

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

 <h4 id="cxx11changes">C++11 Feature Support</h4>
 <p>Clang 3.0 adds support for
 <a href="http://clang.llvm.org/cxx_status.html#cxx11">more of the language
 features</a> added in the latest ISO C++ standard,
 <a href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=50372">C++ 2011</a>.
 Use <code>-std=c++11</code> or <code>-std=gnu++11</code> to enable support for
 these features. The following are now considered to be of production quality:
 <ul>
   <li>Range-based <code>for</code> loops</li>
   <li>Alias declarations (a new syntax for <code>typedef</code> declarations),
   including their <code>template</code> forms</li>
   <li>Specifying default values for class data members within a class
   definition</li>
   <li>Constructors delegating to other constructors of the same class</li>
   <li>The <code>override</code> context-sensitive keyword for virtual member
   function declarations</li>
   <li>Explicitly generating default function definitions with
   <code>= default</code></li>
   <li>The <code>nullptr</code> keyword, and the corresponding type</li>
   <li>Raw string literals with arbitary delimiters (for instance,
   <code>R"delim(str"ing)delim"</code>)</li>
   <li>Unicode string literals (for instance, <code>U"\u1234"</code>) and the
   <code>char16_t</code> and <code>char32_t</code> built-in types
   <li><code>noexcept</code> expressions and the <code>noexcept</code> specifier
   on function declarations</li>
   <li><code>alignof</code> expressions and the <code>alignas</code> specifier on
   variable declarations</li>
   <li>A full set of <a href="http://clang.llvm.org/docs/LanguageExtensions.html#checking_type_traits">type traits</a>,
   sufficient to support C++11 standard libraries</li>
 </ul>
 All warning and language selection flags which previously accepted
 <code>c++0x</code> now accept <code>c++11</code>. The old <code>c++0x</code>
 form remains as an alias.

 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="objcchanges">Objective-C Language Changes in Clang</h3>
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 Clang 3.0 introduces several new Objective-C language features and improvements.

 <h4 id="objc_arc">Objective-C Automatic Reference Counting</h4>
 <!-- This is really just a stub for John to flesh out regarding ARC. -->
 ARC provides automated memory management for Objective-C programs that is
 compatible with existing retain/release code.  ARC is carefully built to
 be a reliable programming model that errs on the side of producing a
 compiler error instead of silently producing a runtime memory problem.
 ARC automates Objective-C objects, not malloc data, file descriptors,
 CoreFoundation datatypes or anything else. For more details, see the
 <a href="http://clang.llvm.org/docs/AutomaticReferenceCounting.html">full specification</a>.

 <h4 id="objc_instancetype">Objective-C Related Result Types / Instance
 Types</h4>
 Allows declaring new methods which follow the Cocoa conventions for methods
 such as <code>init</code> which always return objects that are an instance of
 the receiving class's type. For more details, see the
 <a href="http://clang.llvm.org/docs/LanguageExtensions.html#objc_instancetype">language extension documentation</a>.

 <!--
 This is a stub for David Chisnall to fill out.

 <h4 id="objc_gnuruntime">Improved support for the GNU Runtime</h4>
 ....
 -->

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

 These are major API changes that have happened since the 2.9 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.

 <h4 id="macroexpansion">Switched terminology from "instantiation" to "expansion"
   for macros</h4>
 A great deal of comments and code changes fell out of this, but also every API
 relating to macros with the word "instantiation" (or some variant thereof) was
 renamed. An incomplete list of the most note-worthy ones is here:
 <ul>
   <li><code>MacroInstantiation</code> became <code>MacroExpansion</code></li>
   <li><code>SourceManager::getInstantiationLoc</code> became
   <code>SourceManager::getExpansionLoc</code></li>
   <li><code>SourceManager::getInstantiationRange</code> became
   <code>SourceManager::getExpansionRange</code></li>
   <li><code>SourceManager::getImmediateInstantiationRange</code> became
   <code>SourceManager::getImmediateExpansionRange</code></li>
   <li><code>SourceManager::getDecomposedInstantiationLoc</code> became
   <code>SourceManager::getDecomposedExpansionLoc</code></li>
   <li><code>SourceManager::getInstantiationColumnNumber</code> became
   <code>SourceManager::getExpansionColumnNumber</code></li>
   <li><code>SourceManager::getInstantiationLineNumber</code> became
   <code>SourceManager::getExpansionLineNumber</code></li>
   <!-- TODO: Make this more complete! -->
 </ul>

 <h4 id="diagnosticrename">Diagnostic class names were shuffled</h4>
 <ul>
   <li><code>Diagnostic</code> became <code>DiagnosticEngine</code></li>
   <li><code>DiagnosticClient</code> became <code>DiagnosticConsumer</code></li>
   <li><code>DiagnosticInfo</code> became <code>Diagnostic</code></li>
 </ul>
 Subclasses of <code>DiagnosticConsumer</code> were also then renamed to end with
 <code>Consumer</code>.

 <!-- ======================================================================= -->
 <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?

 -->

 </body>
 </html>
	<html>
	<head>
	<title>Clang 3.0 Release Notes</title>
	<link type="text/css" rel="stylesheet" href="../menu.css" />
	<link type="text/css" rel="stylesheet" href="../content.css" />
	<style type="text/css">
	td {
	vertical-align: top;
	}
	</style>
	</head>
	<body>

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

	<div id="content">

	<h1>Clang 3.0 Release Notes</h1>

	<img align=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 3.0?</a>
	<ul>
	<li><a href="#majorfeatures">Major New Features</a></li>
	<li><a href="#cchanges">C Language Changes</a></li>
	<li><a href="#cxxhanges">C++ Language Changes</a></li>
	<li><a href="#objchanges">Objective-C Language Changes</a></li>
	<li><a href="#apichanges">Internal API 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 LLVM 3.0
	release.<br>
	You may prefer the
	<a href="http://llvm.org/releases/2.9/docs/ReleaseNotes.html">LLVM 2.9
	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 3.0. 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 3.0?</h2>
	<!-- ======================================================================= -->

	<p>Some of the major new features and improvements to Clang are listed here.
	Generic improvements to Clang as a whole or two 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">A multitude of improvements to Clang's diagnostics</h4>
	Clang's diagnostics are constantly being improved to catch more issues, explain
	them more clearly, and provide more accurate source information about them.
	A few improvements since the 2.9 release that have a particularly high impact:
	<ul>
	<li>Substantially shorter messages due to better recovery, fewer include
	stacks, and tuning verbose features such as 'a.k.a.' type printing.</li>
	<li>
	Able to recover and correct from misspelled type names at the beging of
	statements. For example, Clang now emits:
	<pre><b>t.c:6:3: <span class="error">error:</span> use of undeclared identifier 'integer'; did you mean 'Integer'?</b>
	integer *i = 0;
	<span class="caret">^~~~~~~</span>
	Integer
	<b>t.c:1:13: note:</b> 'Integer' declared here
	typedef int Integer;
	<span class="caret">^</span></pre>
	</li>
	<li>Expanded typo correction to (among other improvements) look across
	namespaces and suggest namespace qualifiers in addition to misspellings of the
	identifier itself.</li>
	<li>More rich macro expansion backtraces and some (limited) fix-it hints when
	diagnostics stem from macro arguments.</li>
	<li>Many new warnings have been added to catch common, bug-prone code
	patterns.</li>
	<li>Uninitialized values Clang warning was rewritten to be more accurate,
	faster, and able to differentiate between the <em>possibility</em> of an
	uninitialized use and the <em>certainty</em> of an uninitialized use.</li>
	</ul>

	<h4 id="libclang">This release saw significant improvements to <code>libclang</code></h4>
	<ul>
	<li>A broader set of the <code>libclang</code> API is exposed in the Python
	bindings.</li>
	<li>Much more of the Clang AST is exposed through <code>libclang</code>'s APIs
	and cursors.</li>
	<li>Cursors can now walk more effectively through macros, especially arguments
	to function-style macros, and resolve to the underlying AST.</li>
	<li>Improved code completion surrounding macros, macro arguments, and
	token pasting.</li>
	<li>Improved code completion for in-class member functions.</li>
	<li>Crash recovery for <code>libclang</code> clients.</li>
	<!-- Doug or Ted may want to flesh this out if there are relevant details I'm
	glossing over... -->
	</ul>

	<h4 id="driver">The Clang GCC-compatible command-line driver improved dramatically</h4>
	A great deal of work went into the GCC-compatible driver for the 3.0 release
	making it support more operating systems, emulate GCC behavior more accurately,
	and support a much broader range of Linux distributions out of the box.
	<ul>
	<li>More accurate support for hardware architecture pre-defined macros (e.g.,
	__i686__).</li>
	<li>Robust library and header search paths for the vast majority of x86 and
	x86-64 Linux distributions.</li>
	<li>Improved support for newer Darwin platforms.</li>
	<li>Partial support for <code>--sysroot=...</code> based cross-compiling on
	Linux (and similar) host systems.</li>
	<li>Improved support for locating and using libcxx when installed, especially
	on Darwin.</li>
	<!-- There are likely more Darwin-specific improvements to mention here? -->
	<!-- What support was added for FreeBSD? NetBSD? Anything noteworthy? -->
	<li>Automatic detection of Clang crashes in the driver and preparation of
	reproduction steps for filing bug reports.</li><!-- Chad, feel free to add
	more details here. -->
	</ul>

	<h4 id="ppcallbacks">Expanded support for instrumenting the preprocessor through
	callbacks</h4>
	Several enhancements were made to the <code>PPCallbacks</code> interface to
	expand the information available to tools and library users of Clang that wish
	to introspect the preprocessing.
	<ul>
	<li>The exact text used between the <code>""</code>s or <code><></code>s is reported.</li>
	<li>The header search path used to locate the header is reported.</li>
	<li>Missing files during including headers reported.</li>
	<li>The exact source range for expanded macros can be retrieved.</li>
	</ul>

	<h4 id="windows">Clang is building and tested regularly on Windows and can
	compile limited subsets of code on Windows</h4>
	Clang is regularly built and tested on a variety of Windows platforms including
	MinGW 32-bit and 64-bit, Cygwin, and natively with MSVC. In addition, Clang can
	be used as a compiler in a few Windows contexts.
	<ul>
	<li>Normal compilation supported for the MinGW target platform, in both 32-bit
	and 64-bit, and the Cygwin target platform.</li>
	<li>Parsing and AST support for Windows Structured Exception Handling.</li>
	<li>New -fms-compatibility flag to handle MSVC constructs that could change
	the meaning of an otherwise well formed program</li>
	<li>clang can now parse all the MSVC 2010 standard C++ header files
	in the nominal case, (still need to specifiy -nobuiltininc for some headers).</li>
	<li>Improved support for MFC code parsing, (still a work in progress).</li>
	<li>Add support for function template specialization at class scope (-fms-extensions mode).</li>
	<li>Add support for Microsoft __if_exists/__if_not_exists statements (-fms-extensions mode).</li>
	</ul>

	<h4 id="availability">New availability attribute to detect and warn about API
	usage across OS X and iOS versions</h4>
	Clang now supports an attribute which documents the availability of an API
	across various platforms and releases, allowing interfaces to include
	information about what OS versions support the relevant features. Based on the
	targeted version of a compile, warnings for deprecated and unavailable
	interfaces will automatically be provided by Clang.

	<h4 id="threadsafety">Thread Safety annotations and analysis-based warnings</h4>
	A set of annotations were introduced to Clang to describe the various
	thread-safety concerns of a program, and an accompanying set of analysis based
	warnings will diagnose clearly unsafe code patterns. The annotations are
	described in the
	<a href="http://clang.llvm.org/docs/LanguageExtensions.html#threadsafety">extension specification</a>,
	and the warnings currently supported include:
	<ul>
	<li>Calling functions without the required locks</li>
	<li>Reading variables without the required locks</li>
	<li>Writing to variables without an exclusive lock (even if holding a shared
	lock)</li>
	<li>Imbalance between locks and unlocks across loop entries and exits</li>
	<li>Acquiring or releasing locks out of order</li>
	</ul>

	<h4 id="incompleteast">Improved support for partially constructed and/or
	incomplete ASTs</h4>
	For users such as LLDB that are dynamically forming C++ ASTs, sometimes it is
	either necessary or useful to form a partial or incomplete AST. Support for
	these use cases have improved through the introduction of "unknown" types and
	other AST constructs designed specifically for use cases without complete
	information about the C++ construct being formed.

	<h4 id="opencl">Initial work to support compiling OpenCL C with Clang</h4>
	<p>Clang has some (limited) support for compiling OpenCL C. The 3.0
	release adds support for the <tt>vec_step</tt> operator, address space
	qualifiers (<tt>__private</tt>, <tt>__global</tt>, <tt>__local</tt> and
	<tt>__constant</tt>), improved vector literal support and code generation
	support for the <a href="http://llvm.org/docs/ReleaseNotes.html#PTX">PTX
	target</a>.</p>

	<p>Using the <a href="http://www.pcc.me.uk/~peter/libclc/">libclc library</a>
	to supply OpenCL C built-ins, you can use Clang to compile OpenCL C code
	into PTX and execute it by loading the resulting PTX as a binary blob using
	the nVidia OpenCL library. It has been tested with several OpenCL programs,
	including some from the nVidia GPU Computing SDK, and the performance is on
	par with the nVidia compiler.</p>

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

	<h4 id="c1xchanges">C1X Feature Support</h4>

	<p>Clang 3.0 adds support for the
	<a href="http://clang.llvm.org/docs/LanguageExtensions.html#c1x">
	<code>_Alignas</code>, <code>_Generic</code>, and <code>_Static_assert</code>
	keywords</a>, drafted for inclusion in the next C standard, which is
	provisionally known as C1X. Use <code>-std=c1x</code> or <code>-std=gnu1x</code>
	to enable support for the new language standard. These features are
	backwards-compatible and are available as an extension in all language
	modes.</p>

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

	<h4 id="cxx11changes">C++11 Feature Support</h4>
	<p>Clang 3.0 adds support for
	<a href="http://clang.llvm.org/cxx_status.html#cxx11">more of the language
	features</a> added in the latest ISO C++ standard,
	<a href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=50372">C++ 2011</a>.
	Use <code>-std=c++11</code> or <code>-std=gnu++11</code> to enable support for
	these features. The following are now considered to be of production quality:
	<ul>
	<li>Range-based <code>for</code> loops</li>
	<li>Alias declarations (a new syntax for <code>typedef</code> declarations),
	including their <code>template</code> forms</li>
	<li>Specifying default values for class data members within a class
	definition</li>
	<li>Constructors delegating to other constructors of the same class</li>
	<li>The <code>override</code> context-sensitive keyword for virtual member
	function declarations</li>
	<li>Explicitly generating default function definitions with
	<code>= default</code></li>
	<li>The <code>nullptr</code> keyword, and the corresponding type</li>
	<li>Raw string literals with arbitary delimiters (for instance,
	<code>R"delim(str"ing)delim"</code>)</li>
	<li>Unicode string literals (for instance, <code>U"\u1234"</code>) and the
	<code>char16_t</code> and <code>char32_t</code> built-in types
	<li><code>noexcept</code> expressions and the <code>noexcept</code> specifier
	on function declarations</li>
	<li><code>alignof</code> expressions and the <code>alignas</code> specifier on
	variable declarations</li>
	<li>A full set of <a href="http://clang.llvm.org/docs/LanguageExtensions.html#checking_type_traits">type traits</a>,
	sufficient to support C++11 standard libraries</li>
	</ul>
	All warning and language selection flags which previously accepted
	<code>c++0x</code> now accept <code>c++11</code>. The old <code>c++0x</code>
	form remains as an alias.

	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	<h3 id="objcchanges">Objective-C Language Changes in Clang</h3>
	<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
	Clang 3.0 introduces several new Objective-C language features and improvements.

	<h4 id="objc_arc">Objective-C Automatic Reference Counting</h4>
	<!-- This is really just a stub for John to flesh out regarding ARC. -->
	ARC provides automated memory management for Objective-C programs that is
	compatible with existing retain/release code. ARC is carefully built to
	be a reliable programming model that errs on the side of producing a
	compiler error instead of silently producing a runtime memory problem.
	ARC automates Objective-C objects, not malloc data, file descriptors,
	CoreFoundation datatypes or anything else. For more details, see the
	<a href="http://clang.llvm.org/docs/AutomaticReferenceCounting.html">full specification</a>.

	<h4 id="objc_instancetype">Objective-C Related Result Types / Instance
	Types</h4>
	Allows declaring new methods which follow the Cocoa conventions for methods
	such as <code>init</code> which always return objects that are an instance of
	the receiving class's type. For more details, see the
	<a href="http://clang.llvm.org/docs/LanguageExtensions.html#objc_instancetype">language extension documentation</a>.

	<!--
	This is a stub for David Chisnall to fill out.

	<h4 id="objc_gnuruntime">Improved support for the GNU Runtime</h4>
	....
	-->

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

	These are major API changes that have happened since the 2.9 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.

	<h4 id="macroexpansion">Switched terminology from "instantiation" to "expansion"
	for macros</h4>
	A great deal of comments and code changes fell out of this, but also every API
	relating to macros with the word "instantiation" (or some variant thereof) was
	renamed. An incomplete list of the most note-worthy ones is here:
	<ul>
	<li><code>MacroInstantiation</code> became <code>MacroExpansion</code></li>
	<li><code>SourceManager::getInstantiationLoc</code> became
	<code>SourceManager::getExpansionLoc</code></li>
	<li><code>SourceManager::getInstantiationRange</code> became
	<code>SourceManager::getExpansionRange</code></li>
	<li><code>SourceManager::getImmediateInstantiationRange</code> became
	<code>SourceManager::getImmediateExpansionRange</code></li>
	<li><code>SourceManager::getDecomposedInstantiationLoc</code> became
	<code>SourceManager::getDecomposedExpansionLoc</code></li>
	<li><code>SourceManager::getInstantiationColumnNumber</code> became
	<code>SourceManager::getExpansionColumnNumber</code></li>
	<li><code>SourceManager::getInstantiationLineNumber</code> became
	<code>SourceManager::getExpansionLineNumber</code></li>
	<!-- TODO: Make this more complete! -->
	</ul>

	<h4 id="diagnosticrename">Diagnostic class names were shuffled</h4>
	<ul>
	<li><code>Diagnostic</code> became <code>DiagnosticEngine</code></li>
	<li><code>DiagnosticClient</code> became <code>DiagnosticConsumer</code></li>
	<li><code>DiagnosticInfo</code> became <code>Diagnostic</code></li>
	</ul>
	Subclasses of <code>DiagnosticConsumer</code> were also then renamed to end with
	<code>Consumer</code>.

	<!-- ======================================================================= -->
	<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?

	-->

	</body>
	</html>