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16<div id="content">
17
18<h1>Clang 3.0 Release Notes</h1>
19
20<img align=right src="http://llvm.org/img/DragonSmall.png"
21 width="136" height="136" alt="LLVM Dragon Logo">
22
23<ul>
24 <li><a href="#intro">Introduction</a></li>
25 <li><a href="#whatsnew">What's New in Clang 3.0?</a>
26 <ul>
27 <li><a href="#majorfeatures">Major New Features</a></li>
28 <li><a href="#cchanges">C Language Changes</a></li>
29 <li><a href="#cxxhanges">C++ Language Changes</a></li>
30 <li><a href="#objchanges">Objective-C Language Changes</a></li>
31 <li><a href="#apichanges">Internal API Changes</a></li>
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]32 </ul>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]33 </li>
34 <li><a href="#knownproblems">Known Problems</a></li>
35 <li><a href="#additionalinfo">Additional Information</a></li>
36</ul>
37
38<div class="doc_author">
39 <p>Written by the <a href="http://llvm.org/">LLVM Team</a></p>
40</div>
41
42<!--
43<h1 style="color:red">These are in-progress notes for the upcoming LLVM 3.0
44release.<br>
45You may prefer the
46<a href="http://llvm.org/releases/2.9/docs/ReleaseNotes.html">LLVM 2.9
47Release Notes</a>.</h1>
48 -->
49
50<!-- ======================================================================= -->
51<h2 id="intro">Introduction</h2>
52<!-- ======================================================================= -->
53
54<p>This document contains the release notes for the Clang C/C++/Objective-C
55frontend, part of the LLVM Compiler Infrastructure, release 3.0. Here we
56describe the status of Clang in some detail, including major improvements from
57the previous release and new feature work. For the general LLVM release notes,
58see <a href ="http;//llvm.org/docs/ReleaseNotes.html">the LLVM
59 documentation</a>. All LLVM releases may be downloaded from the
60<a href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
61
62<p>For more information about Clang or LLVM, including information about the
63latest release, please check out the main please see the
64<a href="http://clang.llvm.org">Clang Web Site</a> or the
65<a href="http://llvm.org">LLVM Web Site</a>.
66
67<p>Note that if you are reading this file from a Subversion checkout or the main
68Clang web page, this document applies to the <i>next</i> release, not the
69current one. To see the release notes for a specific release, please see the
70<a href="http://llvm.org/releases/">releases page</a>.</p>
71
72<!-- ======================================================================= -->
73<h2 id="whatsnew">What's New in Clang 3.0?</h2>
74<!-- ======================================================================= -->
75
76<p>Some of the major new features and improvements to Clang are listed here.
77Generic improvements to Clang as a whole or two its underlying infrastructure
78are described first, followed by language-specific sections with improvements to
79Clang's support for those languages.</p>
80
81<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
82<h3 id="majorfeatures">Major New Features</h3>
83<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
84
Chandler Carruth58f2cbc2011-11-28 22:34:59 +0000[diff] [blame]85<h4 id="diagnostics">A multitude of improvements to Clang's diagnostics</h4>
86Clang's diagnostics are constantly being improved to catch more issues, explain
87them more clearly, and provide more accurate source information about them.
88A few improvements since the 2.9 release that have a particularly high impact:
89<ul>
90 <li>Substantially shorter messages due to better recovery, fewer include
91 stacks, and tuning verbose features such as 'a.k.a.' type printing.</li>
92 <li>
93 Able to recover and correct from misspelled type names at the begging of statements. For example, Clang now emits:
Richard Smithad5459a2011-11-28 23:16:15 +0000[diff] [blame]94 <pre><b>t.c:6:3: <span class="error">error:</span> use of undeclared identifier 'integer'; did you mean 'Integer'?</b>
Chandler Carruth58f2cbc2011-11-28 22:34:59 +0000[diff] [blame]95 integer *i = 0;
Richard Smithad5459a2011-11-28 23:16:15 +0000[diff] [blame]96 <span class="caret">^~~~~~~</span>
Chandler Carruth58f2cbc2011-11-28 22:34:59 +0000[diff] [blame]97 Integer
Richard Smithad5459a2011-11-28 23:16:15 +0000[diff] [blame]98<b>t.c:1:13: note:</b> 'Integer' declared here
Chandler Carruth58f2cbc2011-11-28 22:34:59 +0000[diff] [blame]99typedef int Integer;
Richard Smithad5459a2011-11-28 23:16:15 +0000[diff] [blame]100 <span class="caret">^</span></pre>
Chandler Carruth58f2cbc2011-11-28 22:34:59 +0000[diff] [blame]101 </li>
102 <li>Expanded typo correction to (among other improvements) look across
103 namespaces and suggest namespace qualifiers in addition to misspellings of the
104 identifier itself.</li>
105 <li>More rich macro expansion backtraces and some (limited) fix-it hints when
106 diagnostics stem from macro arguments.</li>
Chandler Carruth2f376852011-11-28 22:54:33 +0000[diff] [blame]107 <li>Many new warnings have been added to catch common, bug-prone code
108 patterns.</li>
109 <li>Uninitialized values Clang warning was rewritten to be more accurate,
110 faster, and able to differentiate between the <em>possibility</em> of an
111 uninitialized use and the <em>certainty</em> of an uninitialized use.</li>
Chandler Carruth58f2cbc2011-11-28 22:34:59 +0000[diff] [blame]112</ul>
113
Chandler Carruth9a167122011-11-28 22:43:32 +0000[diff] [blame]114<h4 id="libclang">This release saw significant improvements to <code>libclang</code></h4>
115<ul>
116 <li>A broader set of the <code>libclang</code> API is exposed in the Python
117 bindings.</li>
118 <li>Much more of the Clang AST is exposed through <code>libclang</code>'s APIs
119 and cursors.</li>
120 <li>Cursors can now walk more effectively through macros, especially arguments
121 to function-style macros, and resolve to the underlying AST.</li>
122 <li>Improved code completion surrounding macros, macro arguments, and
123 token pasting.</li>
124 <li>Improved code completion for in-class member functions.</li>
125 <li>Crash recovery for <code>libclang</code> clients.</li>
126 <!-- Doug or Ted may want to flesh this out if there are relevant details I'm
127 glossing over... -->
128</ul>
129
Chandler Carruthb882a1d2011-11-28 21:56:30 +0000[diff] [blame]130<h4 id="driver">The Clang GCC-compatible command-line driver improved dramatically</h4>
131A great deal of work went into the GCC-compatible driver for the 3.0 release
132making it support more operating systems, emulate GCC behavior more accurately,
133and support a much broader range of Linux distributions out of the box.
134<ul>
135 <li>More accurate support for hardware architecture pre-defined macros (e.g.,
136 __i686__).</li>
137 <li>Robust library and header search paths for the vast majority of x86 and
138 x86-64 Linux distributions.</li>
139 <li>Improved support for newer Darwin platforms.</li>
140 <li>Partial support for <code>--sysroot=...</code> based cross-compiling on
141 Linux (and similar) host systems.</li>
142 <li>Improved support for locating and using libcxx when installed, especially
143 on Darwin.</li>
144 <!-- There are likely more Darwin-specific improvements to mention here? -->
145 <!-- What support was added for FreeBSD? NetBSD? Anything noteworthy? -->
Chandler Carruth2f376852011-11-28 22:54:33 +0000[diff] [blame]146 <li>Automatic detection of Clang crashes in the driver and preparation of
147 reproduction steps for filing bug reports.</li><!-- Chad, feel free to add
148 more details here. -->
Chandler Carruthb882a1d2011-11-28 21:56:30 +0000[diff] [blame]149</ul>
150
Chandler Carruthc6f2af32011-11-28 19:17:25 +0000[diff] [blame]151<h4 id="ppcallbacks">Expanded support for instrumenting the preprocessor through
152 callbacks</h4>
Chandler Carruthf16d7252011-11-28 21:47:51 +0000[diff] [blame]153Several enhancements were made to the <code>PPCallbacks</code> interface to
154expand the information available to tools and library users of Clang that wish
155to introspect the preprocessing.
Chandler Carruthc6f2af32011-11-28 19:17:25 +0000[diff] [blame]156<ul>
157 <li>The exact text used between the <code>""</code>s or <code>&lt;&gt;</code>s is reported.</li>
158 <li>The header search path used to locate the header is reported.</li>
159 <li>Missing files during including headers reported.</li>
160 <li>The exact source range for expanded macros can be retrieved.</li>
161</ul>
162
Chandler Carruth185e9302011-11-28 23:11:27 +0000[diff] [blame]163<h4 id="windows">Clang is building and tested regularly on Windows and can
164 compile limited subsets of code on Windows</h4>
165Clang is regularly built and tested on a variety of Windows platforms including
166MinGW 32-bit and 64-bit, Cygwin, and natively with MSVC. In addition, Clang can
167be used as a compiler in a few Windows contexts.
168<ul>
169 <li>Normal compilation supported for the MinGW target platform, in both 32-bit
170 and 64-bit, and the Cygwin target platform.</li>
171 <li>Parsing and AST support for Windows Structured Exception Handling.</li>
Francois Pichet551988f2011-11-28 23:30:46 +0000[diff] [blame]172 <li>New -fms-compatibility flag to handle MSVC constructs that could change
173 the meaning of an otherwise well formed program</li>
174 <li>clang can now parse all the MSVC 2010 standard C++ header files
175 in the nominal case, (still need to specifiy -nobuiltininc for some headers).</li>
176 <li>Improved support for MFC code parsing, (still a work in progress).</li>
Francois Pichet0c2198a2011-11-28 23:46:15 +0000[diff] [blame]177 <li>Add support for function template specialization at class scope (-fms-extensions mode).</li>
178 <li>Add support for Microsoft __if_exists/__if_not_exists statements (-fms-extensions mode).</li>
Chandler Carruth185e9302011-11-28 23:11:27 +0000[diff] [blame]179</ul>
180
Chandler Carruth45901b32011-11-29 00:15:26 +0000[diff] [blame]181<h4 id="availability">New availability attribute to detect and warn about API
182usage across OS X and iOS versions</h4>
183Clang now supports an attribute which documents the availability of an API
184across various platforms and releases, allowing interfaces to include
185information about what OS versions support the relevant features. Based on the
186targeted version of a compile, warnings for deprecated and unavailable
187interfaces will automatically be provided by Clang.
188
189<h4 id="threadsafety">Thread Safety annotations and analysis-based warnings</h4>
190A set of annotations were introduced to Clang to describe the various
191thread-safety concerns of a program, and an accompanying set of analysis based
192warnings will diagnose clearly unsafe code patterns. The annotations are
193described in the
194<a href="http://clang.llvm.org/docs/LanguageExtensions.html#threadsafety">extension specification</a>,
195and the warnings currently supported include:
196<ul>
197 <li>Calling functions without the required locks</li>
198 <li>Reading variables without the required locks</li>
199 <li>Writing to variables without an exclusive lock (even if holding a shared
200 lock)</li>
201 <li>Imbalance between locks and unlocks across loop entries and exits</li>
202 <li>Acquiring or releasing locks out of order</li>
203</ul>
204
205<h4 id="incompleteast">Improved support for partially constructed and/or
206incomplete ASTs</h4>
207For users such as LLDB that are dynamically forming C++ ASTs, sometimes it is
208either necessary or useful to form a partial or incomplete AST. Support for
209these use cases have improved through the introduction of "unknown" types and
210other AST constructs designed specifically for use cases without complete
211information about the C++ construct being formed.
212
Chandler Carrutha0df07d2011-11-28 22:17:58 +0000[diff] [blame]213<!--
214Need Peter and/or Tanya to flesh this out if we want it in 3.0's notes.. The
215state isn't clear just from documentation or commit logs.
216
217<h4 id="opencl">Initial work to support compiling OpenCL with Clang</h4>
218Clang has some (limited) support for compiling OpenCL.
219-->
220
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]221<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
222<h3 id="cchanges">C Language Changes in Clang</h3>
223<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
224
Richard Smith62d730f2011-11-28 22:48:25 +0000[diff] [blame]225<h4 id="c1xchanges">C1X Feature Support</h4>
226
227<p>Clang 3.0 adds support for the
228<a href="http://clang.llvm.org/docs/LanguageExtensions.html#c1x">
229<code>_Alignas</code>, <code>_Generic</code>, and <code>_Static_assert</code>
230keywords</a>, drafted for inclusion in the next C standard, which is
231provisionally known as C1X. Use <code>-std=c1x</code> or <code>-std=gnu1x</code>
232to enable support for the new language standard. These features are
233backwards-compatible and are available as an extension in all language
234modes.</p>
235
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]236<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
237<h3 id="cxxchanges">C++ Language Changes in Clang</h3>
238<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
239
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]240<h4 id="cxx11changes">C++11 Feature Support</h4>
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]241<p>Clang 3.0 adds support for
242<a href="http://clang.llvm.org/cxx_status.html#cxx11">more of the language
Richard Smith47931382011-11-28 23:35:03 +0000[diff] [blame]243features</a> added in the latest ISO C++ standard,
244<a href="http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=50372">C++ 2011</a>.
245Use <code>-std=c++11</code> or <code>-std=gnu++11</code> to enable support for
246these features. The following are now considered to be of production quality:
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]247<ul>
Chandler Carruthf16d7252011-11-28 21:47:51 +0000[diff] [blame]248 <li>Range-based <code>for</code> loops</li>
249 <li>Alias declarations (a new syntax for <code>typedef</code> declarations),
250 including their <code>template</code> forms</li>
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]251 <li>Specifying default values for class data members within a class
252 definition</li>
253 <li>Constructors delegating to other constructors of the same class</li>
Chandler Carruthf16d7252011-11-28 21:47:51 +0000[diff] [blame]254 <li>The <code>override</code> context-sensitive keyword for virtual member
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]255 function declarations</li>
Chandler Carruthf16d7252011-11-28 21:47:51 +0000[diff] [blame]256 <li>Explicitly generating default function definitions with
257 <code>= default</code></li>
258 <li>The <code>nullptr</code> keyword, and the corresponding type</li>
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]259 <li>Raw string literals with arbitary delimiters (for instance,
Chandler Carruthf16d7252011-11-28 21:47:51 +0000[diff] [blame]260 <code>R"delim(str"ing)delim"</code>)</li>
261 <li>Unicode string literals (for instance, <code>U"\u1234"</code>) and the
262 <code>char16_t</code> and <code>char32_t</code> built-in types
263 <li><code>noexcept</code> expressions and the <code>noexcept</code> specifier
264 on function declarations</li>
265 <li><code>alignof</code> expressions and the <code>alignas</code> specifier on
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]266 variable declarations</li>
267 <li>A full set of <a href="http://clang.llvm.org/docs/LanguageExtensions.html#checking_type_traits">type traits</a>,
268 sufficient to support C++11 standard libraries</li>
269</ul>
Chandler Carruthbc02a042011-11-28 21:55:34 +0000[diff] [blame]270All warning and language selection flags which previously accepted
271<code>c++0x</code> now accept <code>c++11</code>. The old <code>c++0x</code>
272form remains as an alias.
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]273
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]274<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
275<h3 id="objcchanges">Objective-C Language Changes in Clang</h3>
276<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
Chandler Carruth4d582122011-11-29 00:15:23 +0000[diff] [blame]277Clang 3.0 introduces several new Objective-C language features and improvements.
278
279<h4 id="objc_arc">Objective-C Automatic Reference Counting</h4>
280<!-- This is really just a stub for John to flesh out regarding ARC. -->
281ARC provides automated memory management for Objective-C programs that is
282compatible with existing retain/release code. ARC is carefully built to
283be a reliable programming model that errs on the side of producing a
284compiler error instead of silently producing a runtime memory problem.
285ARC automates Objective-C objects, not malloc data, file descriptors,
286CoreFoundation datatypes or anything else. For more details, see the
287<a href="http://clang.llvm.org/docs/AutomaticReferenceCounting.html">full specification</a>.
288
289<h4 id="objc_instancetype">Objective-C Related Result Types / Instance
290Types</h4>
291Allows declaring new methods which follow the Cocoa conventions for methods
292such as <code>init</code> which always return objects that are an instance of
293the receiving class's type. For more details, see the
294<a href="http://clang.llvm.org/docs/LanguageExtensions.html#objc_instancetype">language extension documentation</a>.
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]295
Chandler Carruth52e375e2011-11-29 00:15:25 +0000[diff] [blame]296<!--
297This is a stub for David Chisnall to fill out.
298
299<h4 id="objc_gnuruntime">Improved support for the GNU Runtime</h4>
300....
301-->
302
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]303<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
304<h3 id="apichanges">Internal API Changes</h3>
305<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
306
Chandler Carruthc4dbffa2011-11-28 18:55:47 +0000[diff] [blame]307These are major API changes that have happened since the 2.9 release of Clang.
308If upgrading an external codebase that uses Clang as a library, this section
309should help get you past the largest hurdles of upgrading.
310
Chandler Carruth7d727b72011-11-28 19:06:34 +0000[diff] [blame]311<h4 id="macroexpansion">Switched terminology from "instantiation" to "expansion"
312 for macros</h4>
313A great deal of comments and code changes fell out of this, but also every API
314relating to macros with the word "instantiation" (or some variant thereof) was
315renamed. An incomplete list of the most note-worthy ones is here:
316<ul>
317 <li><code>MacroInstantiation</code> became <code>MacroExpansion</code></li>
318 <li><code>SourceManager::getInstantiationLoc</code> became
319 <code>SourceManager::getExpansionLoc</code></li>
320 <li><code>SourceManager::getInstantiationRange</code> became
321 <code>SourceManager::getExpansionRange</code></li>
322 <li><code>SourceManager::getImmediateInstantiationRange</code> became
323 <code>SourceManager::getImmediateExpansionRange</code></li>
324 <li><code>SourceManager::getDecomposedInstantiationLoc</code> became
325 <code>SourceManager::getDecomposedExpansionLoc</code></li>
326 <li><code>SourceManager::getInstantiationColumnNumber</code> became
327 <code>SourceManager::getExpansionColumnNumber</code></li>
328 <li><code>SourceManager::getInstantiationLineNumber</code> became
329 <code>SourceManager::getExpansionLineNumber</code></li>
330 <!-- TODO: Make this more complete! -->
331</ul>
332
Chandler Carruthc4dbffa2011-11-28 18:55:47 +0000[diff] [blame]333<h4 id="diagnosticrename">Diagnostic class names were shuffled</h4>
334<ul>
335 <li><code>Diagnostic</code> became <code>DiagnosticEngine</code></li>
336 <li><code>DiagnosticClient</code> became <code>DiagnosticConsumer</code></li>
337 <li><code>DiagnosticInfo</code> became <code>Diagnostic</code></li>
338</ul>
339Subclasses of <code>DiagnosticConsumer</code> were also then renamed to end with
340<code>Consumer</code>.
341
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]342<!-- ======================================================================= -->
343<h2 id="knownproblems">Significant Known Problems</h2>
344<!-- ======================================================================= -->
345
346<!-- ======================================================================= -->
347<h2 id="additionalinfo">Additional Information</h2>
348<!-- ======================================================================= -->
349
350<p>A wide variety of additional information is available on the
351<a href="http://clang.llvm.org/">Clang web page</a>. The web page contains
352versions of the API documentation which are up-to-date with the Subversion
353version of the source code. You can access versions of these documents specific
354to this release by going into the "<tt>clang/doc/</tt>" directory in the Clang
355tree.</p>
356
357<p>If you have any questions or comments about Clang, please feel free to
358contact us via the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev">
359mailing list</a>.</p>
360
Chandler Carruth59abf062011-11-28 22:12:44 +0000[diff] [blame]361
362<!-- ======================================================================= -->
363<!-- Likely 3.1 release notes -->
364<!-- ======================================================================= -->
365<!--
366This is just a section to hold things that have already gotten started and
367should likely pick up proper release notes in 3.1.
368
369- C1X and C++11 atomics infrastructure and support
370- CUDA support?
371
372-->
373
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]374</body>
375</html>