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Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]5<title>Clang 3.2 Release Notes</title>
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Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]20<h1>Clang 3.2 Release Notes</h1>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]21
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]22<img style="float:right" src="http://llvm.org/img/DragonSmall.png"
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]23 width="136" height="136" alt="LLVM Dragon Logo">
24
25<ul>
26 <li><a href="#intro">Introduction</a></li>
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]27 <li><a href="#whatsnew">What's New in Clang 3.2?</a>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]28 <ul>
29 <li><a href="#majorfeatures">Major New Features</a></li>
Alexey Samsonovf7a4c352012-06-22 11:18:10 +0000[diff] [blame]30 <li><a href="#newflags">New Compiler Flags</a></li>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]31 <li><a href="#cchanges">C Language Changes</a></li>
Richard Smith45fb9952012-02-16 00:32:27 +0000[diff] [blame]32 <li><a href="#cxxchanges">C++ Language Changes</a></li>
Jean-Daniel Dupas3fd80872012-03-03 13:37:22 +0000[diff] [blame]33 <li><a href="#objcchanges">Objective-C Language Changes</a></li>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]34 <li><a href="#apichanges">Internal API Changes</a></li>
Gregory Szorc63419002012-05-12 20:45:56 +0000[diff] [blame]35 <li><a href="#pythonchanges">Python Binding Changes</a></li>
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]36 </ul>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]37 </li>
38 <li><a href="#knownproblems">Known Problems</a></li>
39 <li><a href="#additionalinfo">Additional Information</a></li>
40</ul>
41
42<div class="doc_author">
43 <p>Written by the <a href="http://llvm.org/">LLVM Team</a></p>
44</div>
45
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]46<h1 style="color:red">These are in-progress notes for the upcoming Clang 3.2
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]47release.<br>
48You may prefer the
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]49<a href="http://llvm.org/releases/3.1/docs/ClangReleaseNotes.html">Clang 3.1
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]50Release Notes</a>.</h1>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]51
52<!-- ======================================================================= -->
53<h2 id="intro">Introduction</h2>
54<!-- ======================================================================= -->
55
56<p>This document contains the release notes for the Clang C/C++/Objective-C
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]57 frontend, part of the LLVM Compiler Infrastructure, release 3.2. Here we
58 describe the status of Clang in some detail, including major improvements
59 from the previous release and new feature work. For the general LLVM release
60 notes, see <a href="http://llvm.org/docs/ReleaseNotes.html">the LLVM
61 documentation</a>. All LLVM releases may be downloaded from the
62 <a href="http://llvm.org/releases/">LLVM releases web site</a>.</p>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]63
64<p>For more information about Clang or LLVM, including information about the
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]65 latest release, please check out the main please see the
66 <a href="http://clang.llvm.org">Clang Web Site</a> or the
67 <a href="http://llvm.org">LLVM Web Site</a>.
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]68
69<p>Note that if you are reading this file from a Subversion checkout or the main
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]70 Clang web page, this document applies to the <i>next</i> release, not the
71 current one. To see the release notes for a specific release, please see the
72 <a href="http://llvm.org/releases/">releases page</a>.</p>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]73
74<!-- ======================================================================= -->
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]75<h2 id="whatsnew">What's New in Clang 3.2?</h2>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]76<!-- ======================================================================= -->
77
78<p>Some of the major new features and improvements to Clang are listed here.
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]79 Generic improvements to Clang as a whole or to its underlying infrastructure
80 are described first, followed by language-specific sections with improvements
81 to Clang's support for those languages.</p>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]82
83<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
84<h3 id="majorfeatures">Major New Features</h3>
85<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
86
Richard Smithb2647022012-05-25 02:35:34 +0000[diff] [blame]87<h4 id="diagnostics">Improvements to Clang's diagnostics</h4>
Chandler Carrutha0df07d2011-11-28 22:17:58 +0000[diff] [blame]88
Richard Smithb2647022012-05-25 02:35:34 +0000[diff] [blame]89<p>Clang's diagnostics are constantly being improved to catch more issues,
90explain them more clearly, and provide more accurate source information about
91them. The improvements since the 3.1 release include:</p>
92
93<ul>
94 <li><tt>-Wuninitialized</tt> has been taught to recognise uninitialized uses
95 which always occur when an explicitly-written non-constant condition is either
96 <tt>true</tt> or <tt>false</tt>. For example:
97
98<pre>
99int f(bool b) {
100 int n;
101 if (b)
102 n = 1;
103 return n;
104}
105
Richard Smithbdb97ff2012-05-26 06:20:46 +0000[diff] [blame]106<b>sometimes-uninit.cpp:3:7: <span class="warning">warning:</span> variable 'n' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]</b>
Richard Smithb2647022012-05-25 02:35:34 +0000[diff] [blame]107 if (b)
108 <span class="caret">^</span>
Richard Smithbdb97ff2012-05-26 06:20:46 +0000[diff] [blame]109<b>sometimes-uninit.cpp:5:10: <span class="note">note:</span></b> uninitialized use occurs here
110 return n;
111 <span class="caret">^</span>
112<b>sometimes-uninit.cpp:3:3: <span class="note">note:</span></b> remove the 'if' if its condition is always true
113 if (b)
114 <span class="caret">^~~~~~</span>
Richard Smithb2647022012-05-25 02:35:34 +0000[diff] [blame]115<b>sometimes-uninit.cpp:2:8: <span class="note">note:</span></b> initialize the variable 'n' to silence this warning
116 int n;
117 <span class="caret">^</span>
118 <span class="caret"> = 0</span>
119</pre>
120
121 This functionality can be enabled or disabled separately from
122 <tt>-Wuninitialized</tt> with the <tt>-Wsometimes-uninitialized</tt> warning
123 flag.</li>
Richard Trieue59331a2012-06-27 02:00:20 +0000[diff] [blame]124
125 <li>Template type diffing improves the display of diagnostics with templated
126 types in them.
127
128<pre>
129int f(vector&lt;map&lt;int, double&gt;&gt;);
130int x = f(vector&lt;map&lt;int, float&gt;&gt;());
131</pre>
132 The error message is the same, but the note is different based on the options selected.
133<pre>
134<b>template-diff.cpp:5:9: <span class="error">error:</span> no matching function for call to 'f'</b>
135int x = f(vector&lt;map&lt;int, float&gt;&gt;());
136 <span class="caret">^</span>
137</pre>
138 Templated type diffing with type elision (default):
139<pre>
140<b>template-diff.cpp:4:5: <span class="note">note:</span></b> candidate function not viable: no known conversion from 'vector&lt;map&lt;[...], <span class="template-highlight">float</span>&gt;&gt;' to 'vector&lt;map&lt;[...], <span class="template-highlight">double</span>&gt;&gt;' for 1st argument;
141int f(vector&lt;map&lt;int, double&gt;&gt;);
142 <span class="caret">^</span>
143</pre>
144 Templated type diffing without type elision (-fno-elide-type):
145<pre>
146<b>template-diff.cpp:4:5: <span class="note">note:</span></b> candidate function not viable: no known conversion from 'vector&lt;map&lt;int, <span class="template-highlight">float</span>&gt;&gt;' to 'vector&lt;map&lt;int, <span class="template-highlight">double</span>&gt;&gt;' for 1st argument;
147int f(vector&lt;map&lt;int, double&gt;&gt;);
148 <span class="caret">^</span>
149</pre>
150 Templated tree printing with type elision (-fdiagnostics-show-template-tree):
151<pre>
152<b>template-diff.cpp:4:5: <span class="note">note:</span></b> candidate function not viable: no known conversion for 1st argument;
153 vector&lt;
154 map&lt;
155 [...],
156 [<span class="template-highlight">float</span> != <span class="template-highlight">double</span>]&gt;&gt;
157int f(vector&lt;map&lt;int, double&gt;&gt;);
158 <span class="caret">^</span>
159</pre>
160 Templated tree printing without type elision (-fdiagnostics-show-template-tree -fno-elide-type):
161<pre>
162<b>template-diff.cpp:4:5: <span class="note">note:</span></b> candidate function not viable: no known conversion for 1st argument;
163 vector&lt;
164 map&lt;
165 int,
166 [<span class="template-highlight">float</span> != <span class="template-highlight">double</span>]&gt;&gt;
167int f(vector&lt;map&lt;int, double&gt;&gt;);
168 <span class="caret">^</span>
169</pre>
170
171 </li>
172
Richard Smithb2647022012-05-25 02:35:34 +0000[diff] [blame]173</ul>
174
Hans Wennborg5e2d5de2012-06-23 11:51:46 +0000[diff] [blame]175<h4 id="tlsmodel">Support for <code>tls_model</code> attribute</h4>
176
177<p>Clang now supports the <code>tls_model</code> attribute, allowing code that
178uses thread-local storage to explicitly select which model to use. The available
179models are <code>"global-dynamic"</code>, <code>"local-dynamic"</code>,
180<code>"initial-exec"</code> and <code>"local-exec"</code>. See
181<a href="http://www.akkadia.org/drepper/tls.pdf">ELF Handling For Thread-Local
182 Storage</a> for more information.</p>
183
184<p>The compiler is free to choose a different model if the specified model is not
185supported by the target, or if the compiler determines that a more specific
186model can be used.
187</p>
188
Alexey Samsonovf7a4c352012-06-22 11:18:10 +0000[diff] [blame]189<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
190<h3 id="newflags">New Compiler Flags</h3>
191<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
192<ul>
193 <li><tt>-gline-tables-only</tt> controls the
194 <a href="http://clang.llvm.org/docs/UsersManual.html#debuginfosize">size of debug information</a>.
195 This flag tells Clang to emit debug info which is just enough to obtain stack traces with
196 function names, file names and line numbers (by such tools as gdb or addr2line).
197 Debug info for variables or function parameters is not produced, which reduces
198 the size of the resulting binary.
199</ul>
Manuel Klimek92f74092012-04-04 12:53:16 +0000[diff] [blame]200
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]201<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
202<h3 id="cchanges">C Language Changes in Clang</h3>
203<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
204
Richard Smith45fb9952012-02-16 00:32:27 +0000[diff] [blame]205<h4 id="c11changes">C11 Feature Support</h4>
Richard Smith62d730f2011-11-28 22:48:25 +0000[diff] [blame]206
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]207<p>...</p>
Richard Smith45fb9952012-02-16 00:32:27 +0000[diff] [blame]208
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]209<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
210<h3 id="cxxchanges">C++ Language Changes in Clang</h3>
211<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
212
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]213<h4 id="cxx11changes">C++11 Feature Support</h4>
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]214
215<p>...</p>
Richard Smith855746b2011-11-28 20:02:05 +0000[diff] [blame]216
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]217<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
218<h3 id="objcchanges">Objective-C Language Changes in Clang</h3>
219<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
Chandler Carruth4d582122011-11-29 00:15:23 +0000[diff] [blame]220
Jordan Rose996fa802012-07-05 18:48:30 +0000[diff] [blame]221<ul>
222 <li>
223 <p>It is now an error to compare against the addresses of Objective-C
224 literals. This is usually a simple mistake (using <code>==</code> instead
225 of <code>-isEqual:</code>), and the result depends on the implementation
226 of the various literals, none of which are guaranteed to be uniqued or
227 always newly-allocated.</p>
228 <p>In the past, we allowed comparisons against literal strings
229 (<code>@"..."</code>), since they are currently uniqued across
230 translation units at link time. This is an implementation detail and
231 should not be relied upon. If you are using such code, please use global
232 string constants instead (<code>NSString * const MyConst = @"..."</code>)
233 or use <code>-isEqual:</code>.</p>
234 </li>
235</ul>
Chandler Carruth52e375e2011-11-29 00:15:25 +0000[diff] [blame]236
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]237<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
238<h3 id="apichanges">Internal API Changes</h3>
239<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
240
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]241<p>These are major API changes that have happened since the 3.1 release of
242 Clang. If upgrading an external codebase that uses Clang as a library, this
243 section should help get you past the largest hurdles of upgrading.</p>
Chandler Carruthc4dbffa2011-11-28 18:55:47 +0000[diff] [blame]244
Richard Smith45fb9952012-02-16 00:32:27 +0000[diff] [blame]245<h4 id="api1">API change 1</h4>
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]246
247<p>...</p>
Chandler Carruthc4dbffa2011-11-28 18:55:47 +0000[diff] [blame]248
Gregory Szorc63419002012-05-12 20:45:56 +0000[diff] [blame]249<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
250<h3 id="pythonchanges">Python Binding Changes</h3>
251<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
252
253The following methods have been added:
254<ul>
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]255 <li>...</li>
Gregory Szorc63419002012-05-12 20:45:56 +0000[diff] [blame]256</ul>
257
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]258<!-- ======================================================================= -->
259<h2 id="knownproblems">Significant Known Problems</h2>
260<!-- ======================================================================= -->
261
262<!-- ======================================================================= -->
263<h2 id="additionalinfo">Additional Information</h2>
264<!-- ======================================================================= -->
265
266<p>A wide variety of additional information is available on the
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]267 <a href="http://clang.llvm.org/">Clang web page</a>. The web page contains
268 versions of the API documentation which are up-to-date with the Subversion
269 version of the source code. You can access versions of these documents
270 specific to this release by going into the "<tt>clang/doc/</tt>" directory in
271 the Clang tree.</p>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]272
273<p>If you have any questions or comments about Clang, please feel free to
Bill Wendlingc0bb3122012-05-24 06:42:56 +0000[diff] [blame]274 contact us via
275 the <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev"> mailing
276 list</a>.</p>
Chandler Carruth59abf062011-11-28 22:12:44 +0000[diff] [blame]277
278<!-- ======================================================================= -->
279<!-- Likely 3.1 release notes -->
280<!-- ======================================================================= -->
281<!--
282This is just a section to hold things that have already gotten started and
283should likely pick up proper release notes in 3.1.
284
285- C1X and C++11 atomics infrastructure and support
286- CUDA support?
287
288-->
289
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]290</div>
Chandler Carruthc00c0c32011-11-28 07:16:19 +0000[diff] [blame]291</body>
292</html>