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 | <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="notes">Unorganized Notes</h4> | 
 | <p>These are completely random notes as I'm organizing my thoughts and reviewing | 
 | the history. Anything still here needs to be distilled and turned into proper | 
 | prose in a section of its own. When doing that, delete the notes.</p> | 
 | <ul> | 
 |   <li>Building Clang on windows -- mingw, 32 and 64 bit, native windows builds, | 
 |   cygwin. get chapuni to flesh out details.</li> | 
 |   <li>Compiling C/C++ w/ MinGW (32/64) and Cygwin on Windows -- chapuni</li> | 
 |   <li>C++ -- Parsing and AST support for Windows Structured Exception | 
 |   Handling.</li> | 
 |   <li>OS Availability attribute -- r128127</li> | 
 |   <li>GNU ObjectiveC Runtime support -- David Chisnall</li> | 
 |   <li>Improved AST support for partially constructed nodes and incomplete | 
 |   information for LLDB and other clients which dynamically build AST nodes.</li> | 
 |   <li>Largely complete MSVC-compatible parsing mode -- fpichet</li> | 
 |   <li>Memory reduction -- initializers, macro expansions, source locations, | 
 |   etc.</li> | 
 |   <li>ObjC ARC -- get a blurb from rjmccall</li> | 
 |   <li>ObjC related result type/instancetype</li> | 
 |   <li>Thread Safety attributes and correctness analysis added to Clang.</li> | 
 |   <li>Major improvements to the interactions between serializing and | 
 |   deserializing the AST and the preprocessor -- argiris</li> | 
 | </ul> | 
 |  | 
 | <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 begging of statements. For example, Clang now emits: | 
 |     <code>t.c:6:3: error: use of undeclared identifier 'integer'; did you mean | 
 | 'Integer'? | 
 |   integer *i = 0; | 
 |   ^~~~~~~ | 
 |   Integer | 
 | t.c:1:13: note: 'Integer' declared here | 
 | typedef int Integer; | 
 |             ^</code> | 
 |   </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> | 
 |  | 
 | <!-- | 
 | Nick and/or Rafael will flesh this out into a bit about the CFI / DWARF | 
 | improvements. | 
 |  | 
 | <h4 id="dwarf">DWARF Exception Handling uses CFI...</h4> | 
 | Rafael had a zillion patches to emit stuff using .cfi directives... =] | 
 |  | 
 | --> | 
 |  | 
 | <!-- | 
 | Need Peter and/or Tanya to flesh this out if we want it in 3.0's notes.. The | 
 | state isn't clear just from documentation or commit logs. | 
 |  | 
 | <h4 id="opencl">Initial work to support compiling OpenCL with Clang</h4> | 
 | Clang has some (limited) support for compiling OpenCL. | 
 | --> | 
 |  | 
 | <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> | 
 | <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, C++11. 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> | 
 | <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> | 
 |  | 
 | <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> | 
 | <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> |