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16<!--#include virtual="../menu.html.incl"-->
17
18<div id="content">
19
20<h1>Clang Compiler User's Manual</h1>
21
22<ul>
23<li><a href="#intro">Introduction</a>
24 <ul>
25 <li><a href="#terminology">Terminology</a></li>
26 <li><a href="#basicusage">Basic Usage</a></li>
27 </ul>
28</li>
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]29<li><a href="#commandline">Command Line Options</a>
30 <ul>
31 <li><a href="#cl_diagnostics">Options to Control Error and Warning
32 Messages</a></li>
Chad Rosierb211a4b2012-02-22 19:14:46 +0000[diff] [blame]33 <li><a href="#cl_crash_diagnostics">Options to Control Clang Crash
34 Diagnostics</a></li>
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]35 </ul>
36</li>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]37<li><a href="#general_features">Language and Target-Independent Features</a>
38 <ul>
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]39 <li><a href="#diagnostics">Controlling Errors and Warnings</a>
Chris Lattner3401cf82009-07-12 21:22:10 +0000[diff] [blame]40 <ul>
41 <li><a href="#diagnostics_display">Controlling How Clang Displays Diagnostics</a></li>
42 <li><a href="#diagnostics_mappings">Diagnostic Mappings</a></li>
Chris Lattner67db8cd2010-05-30 23:42:51 +0000[diff] [blame]43 <li><a href="#diagnostics_categories">Diagnostic Categories</a></li>
Chris Lattner3401cf82009-07-12 21:22:10 +0000[diff] [blame]44 <li><a href="#diagnostics_commandline">Controlling Diagnostics via Command Line Flags</a></li>
45 <li><a href="#diagnostics_pragmas">Controlling Diagnostics via Pragmas</a></li>
Richard Smithf122a132012-06-13 20:27:03 +0000[diff] [blame]46 <li><a href="#diagnostics_systemheader">Controlling Diagnostics in System Headers</a></li>
Ted Kremenekf391fa72011-08-18 01:17:05 +0000[diff] [blame]47 <li><a href="#diagnostics_enable_everything">Enabling All Warnings</a></li>
Ted Kremenek2fb11eb2010-08-24 18:12:35 +0000[diff] [blame]48 <li><a href="#analyzer_diagnositics">Controlling Static Analyzer Diagnostics</a></li>
Chris Lattner3401cf82009-07-12 21:22:10 +0000[diff] [blame]49 </ul>
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]50 </li>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]51 <li><a href="#precompiledheaders">Precompiled Headers</a></li>
Mike Stump53664ca2009-12-14 23:53:10 +0000[diff] [blame]52 <li><a href="#codegen">Controlling Code Generation</a></li>
Alexey Samsonov5ab52492012-05-30 06:55:10 +0000[diff] [blame]53 <li><a href="#debuginfosize">Controlling Size of Debug Information</a></li>
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]54 </ul>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]55</li>
56<li><a href="#c">C Language Features</a>
57 <ul>
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]58 <li><a href="#c_ext">Extensions supported by clang</a></li>
59 <li><a href="#c_modes">Differences between various standard modes</a></li>
60 <li><a href="#c_unimpl_gcc">GCC extensions not implemented yet</a></li>
61 <li><a href="#c_unsupp_gcc">Intentionally unsupported GCC extensions</a></li>
62 <li><a href="#c_ms">Microsoft extensions</a></li>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]63 </ul>
64</li>
Richard Smithbdb10182011-11-21 20:54:59 +0000[diff] [blame]65<li><a href="#cxx">C++ Language Features</a>
66 <ul>
67 <li><a href="#cxx_implimits">Controlling implementation limits</a></li>
68 </ul>
69</li>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]70<li><a href="#target_features">Target-Specific Features and Limitations</a>
71 <ul>
72 <li><a href="#target_arch">CPU Architectures Features and Limitations</a>
73 <ul>
74 <li><a href="#target_arch_x86">X86</a></li>
Eli Friedman3b658d32009-06-08 05:12:39 +0000[diff] [blame]75 <li><a href="#target_arch_arm">ARM</a></li>
76 <li><a href="#target_arch_other">Other platforms</a></li>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]77 </ul>
78 </li>
79 <li><a href="#target_os">Operating System Features and Limitations</a>
80 <ul>
81 <li><a href="#target_os_darwin">Darwin (Mac OS/X)</a></li>
82 <li>Linux, etc.</li>
NAKAMURA Takumia75fdb22011-04-04 15:02:41 +0000[diff] [blame]83 <li><a href="#target_os_win32">Windows</a></li>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]84 </ul>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]85 </li>
86 </ul>
87</li>
88</ul>
89
90
91<!-- ======================================================================= -->
92<h2 id="intro">Introduction</h2>
93<!-- ======================================================================= -->
94
95<p>The Clang Compiler is an open-source compiler for the C family of programming
96languages, aiming to be the best in class implementation of these languages.
97Clang builds on the LLVM optimizer and code generator, allowing it to provide
98high-quality optimization and code generation support for many targets. For
99more general information, please see the <a href="http://clang.llvm.org">Clang
100Web Site</a> or the <a href="http://llvm.org">LLVM Web Site</a>.</p>
101
102<p>This document describes important notes about using Clang as a compiler for
103an end-user, documenting the supported features, command line options, etc. If
104you are interested in using Clang to build a tool that processes code, please
105see <a href="InternalsManual.html">the Clang Internals Manual</a>. If you are
Michael J. Spencer8275fc02012-02-12 09:11:39 +0000[diff] [blame]106interested in the <a href="http://clang-analyzer.llvm.org">Clang
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]107Static Analyzer</a>, please see its web page.</p>
108
109<p>Clang is designed to support the C family of programming languages, which
110includes <a href="#c">C</a>, <a href="#objc">Objective-C</a>, <a
111href="#cxx">C++</a>, and <a href="#objcxx">Objective-C++</a> as well as many
112dialects of those. For language-specific information, please see the
113corresponding language specific section:</p>
114
115<ul>
116<li><a href="#c">C Language</a>: K&amp;R C, ANSI C89, ISO C90, ISO C94
117 (C89+AMD1), ISO C99 (+TC1, TC2, TC3). </li>
118<li><a href="#objc">Objective-C Language</a>: ObjC 1, ObjC 2, ObjC 2.1, plus
119 variants depending on base language.</li>
Richard Smithbdb10182011-11-21 20:54:59 +0000[diff] [blame]120<li><a href="#cxx">C++ Language</a></li>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]121<li><a href="#objcxx">Objective C++ Language</a></li>
122</ul>
123
124<p>In addition to these base languages and their dialects, Clang supports a
125broad variety of language extensions, which are documented in the corresponding
126language section. These extensions are provided to be compatible with the GCC,
127Microsoft, and other popular compilers as well as to improve functionality
128through Clang-specific features. The Clang driver and language features are
129intentionally designed to be as compatible with the GNU GCC compiler as
130reasonably possible, easing migration from GCC to Clang. In most cases, code
131"just works".</p>
132
133<p>In addition to language specific features, Clang has a variety of features
134that depend on what CPU architecture or operating system is being compiled for.
Douglas Gregorcd5a5052009-11-09 15:15:41 +0000[diff] [blame]135Please see the <a href="#target_features">Target-Specific Features and
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]136Limitations</a> section for more details.</p>
137
138<p>The rest of the introduction introduces some basic <a
139href="#terminology">compiler terminology</a> that is used throughout this manual
140and contains a basic <a href="#basicusage">introduction to using Clang</a>
141as a command line compiler.</p>
142
143<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
144<h3 id="terminology">Terminology</h3>
145<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
146
147<p>Front end, parser, backend, preprocessor, undefined behavior, diagnostic,
148 optimizer</p>
149
150<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
151<h3 id="basicusage">Basic Usage</h3>
152<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
153
154<p>Intro to how to use a C compiler for newbies.</p>
155<p>
156compile + link
157
158compile then link
159
160debug info
161
162enabling optimizations
163
164picking a language to use, defaults to C99 by default. Autosenses based on
165extension.
166
167using a makefile
168</p>
169
170
171<!-- ======================================================================= -->
172<h2 id="commandline">Command Line Options</h2>
173<!-- ======================================================================= -->
174
175<p>
176This section is generally an index into other sections. It does not go into
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]177depth on the ones that are covered by other sections. However, the first part
178introduces the language selection and other high level options like -c, -g, etc.
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]179</p>
180
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]181
182<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
183<h3 id="cl_diagnostics">Options to Control Error and Warning Messages</h3>
184<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
185
186<p><b>-Werror</b>: Turn warnings into errors.</p>
187<p><b>-Werror=foo</b>: Turn warning "foo" into an error.</p>
188<p><b>-Wno-error=foo</b>: Turn warning "foo" into an warning even if -Werror is
189 specified.</p>
190<p><b>-Wfoo</b>: Enable warning foo</p>
191<p><b>-Wno-foo</b>: Disable warning foo</p>
192<p><b>-w</b>: Disable all warnings.</p>
193<p><b>-pedantic</b>: Warn on language extensions.</p>
194<p><b>-pedantic-errors</b>: Error on language extensions.</p>
195<p><b>-Wsystem-headers</b>: Enable warnings from system headers.</p>
196
Chris Lattner0f0c9632010-04-07 20:49:23 +0000[diff] [blame]197<p><b>-ferror-limit=123</b>: Stop emitting diagnostics after 123 errors have
198 been produced. The default is 20, and the error limit can be disabled with
199 -ferror-limit=0.</p>
200
Douglas Gregor575cf372010-04-20 07:18:24 +0000[diff] [blame]201<p><b>-ftemplate-backtrace-limit=123</b>: Only emit up to 123 template instantiation notes within the template instantiation backtrace for a single warning or error. The default is 10, and the limit can be disabled with -ftemplate-backtrace-limit=0.</p>
202
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]203<!-- ================================================= -->
204<h4 id="cl_diag_formatting">Formatting of Diagnostics</h4>
205<!-- ================================================= -->
206
207<p>Clang aims to produce beautiful diagnostics by default, particularly for new
208users that first come to Clang. However, different people have different
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]209preferences, and sometimes Clang is driven by another program that wants to
210parse simple and consistent output, not a person. For these cases, Clang
211provides a wide range of options to control the exact output format of the
212diagnostics that it generates.</p>
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]213
214<dl>
215
216<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
217<dt id="opt_fshow-column"><b>-f[no-]show-column</b>: Print column number in
218diagnostic.</dt>
219<dd>This option, which defaults to on, controls whether or not Clang prints the
220column number of a diagnostic. For example, when this is enabled, Clang will
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]221print something like:
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]222
223<pre>
224 test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens]
225 #endif bad
226 ^
227 //
228</pre>
229
230<p>When this is disabled, Clang will print "test.c:28: warning..." with no
231column number.</p>
232</dd>
233
234<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
235<dt id="opt_fshow-source-location"><b>-f[no-]show-source-location</b>: Print
236source file/line/column information in diagnostic.</dt>
237<dd>This option, which defaults to on, controls whether or not Clang prints the
238filename, line number and column number of a diagnostic. For example,
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]239when this is enabled, Clang will print something like:
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]240
241<pre>
242 test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens]
243 #endif bad
244 ^
245 //
246</pre>
247
248<p>When this is disabled, Clang will not print the "test.c:28:8: " part.</p>
249</dd>
250
251<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
252<dt id="opt_fcaret-diagnostics"><b>-f[no-]caret-diagnostics</b>: Print source
253line and ranges from source code in diagnostic.</dt>
254<dd>This option, which defaults to on, controls whether or not Clang prints the
255source line, source ranges, and caret when emitting a diagnostic. For example,
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]256when this is enabled, Clang will print something like:
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]257
258<pre>
259 test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens]
260 #endif bad
261 ^
262 //
263</pre>
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]264</dd>
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]265<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
Douglas Gregore8d44dd2010-07-09 16:31:58 +0000[diff] [blame]266<dt id="opt_fcolor_diagnostics"><b>-f[no-]color-diagnostics</b>: </dt>
267<dd>This option, which defaults to on when a color-capable terminal is
268 detected, controls whether or not Clang prints diagnostics in color.
269 When this option is enabled, Clang will use colors to highlight
270 specific parts of the diagnostic, e.g.,
Chris Lattner4e1c53d2011-01-24 03:47:34 +0000[diff] [blame]271 <pre>
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]272 <b><span style="color:black">test.c:28:8: <span style="color:magenta">warning</span>: extra tokens at end of #endif directive [-Wextra-tokens]</span></b>
Chris Lattner4e1c53d2011-01-24 03:47:34 +0000[diff] [blame]273 #endif bad
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]274 <span style="color:green">^</span>
275 <span style="color:green">//</span>
Douglas Gregore8d44dd2010-07-09 16:31:58 +0000[diff] [blame]276</pre>
Chris Lattner4e1c53d2011-01-24 03:47:34 +0000[diff] [blame]277
278<p>When this is disabled, Clang will just print:</p>
279
280<pre>
281 test.c:2:8: warning: extra tokens at end of #endif directive [-Wextra-tokens]
282 #endif bad
283 ^
284 //
285</pre>
286</dd>
Douglas Gregore8d44dd2010-07-09 16:31:58 +0000[diff] [blame]287<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
Douglas Gregorc9471b02011-05-21 17:07:29 +0000[diff] [blame]288<dt id="opt_fdiagnostics-format"><b>-fdiagnostics-format=clang/msvc/vi</b>:
289Changes diagnostic output format to better match IDEs and command line tools.</dt>
290<dd>This option controls the output format of the filename, line number, and column printed in diagnostic messages. The options, and their affect on formatting a simple conversion diagnostic, follow:
291
292 <dl>
293 <dt><b>clang</b> (default)</dt>
294 <dd>
295 <pre>t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int'</pre>
296 </dd>
297
298 <dt><b>msvc</b></dt>
299 <dd>
300 <pre>t.c(3,11) : warning: conversion specifies type 'char *' but the argument has type 'int'</pre>
301 </dd>
302
303 <dt><b>vi</b></dt>
304 <dd>
305 <pre>t.c +3:11: warning: conversion specifies type 'char *' but the argument has type 'int'</pre>
306 </dd>
307 </dl>
308</dd>
309
310<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
Argyrios Kyrtzidis477aab62011-05-25 05:05:01 +0000[diff] [blame]311<dt id="opt_fdiagnostics-show-name"><b>-f[no-]diagnostics-show-name</b>:
312Enable the display of the diagnostic name.</dt>
313<dd>This option, which defaults to off, controls whether or not
Benjamin Kramer665a8dc2012-01-15 15:26:07 +0000[diff] [blame]314Clang prints the associated name.<p></p></dd>
Argyrios Kyrtzidis477aab62011-05-25 05:05:01 +0000[diff] [blame]315<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]316<dt id="opt_fdiagnostics-show-option"><b>-f[no-]diagnostics-show-option</b>:
317Enable <tt>[-Woption]</tt> information in diagnostic line.</dt>
318<dd>This option, which defaults to on,
319controls whether or not Clang prints the associated <A
320href="#cl_diag_warning_groups">warning group</a> option name when outputting
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]321a warning diagnostic. For example, in this output:
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]322
323<pre>
324 test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens]
325 #endif bad
326 ^
327 //
328</pre>
329
330<p>Passing <b>-fno-diagnostics-show-option</b> will prevent Clang from printing
331the [<a href="#opt_Wextra-tokens">-Wextra-tokens</a>] information in the
332diagnostic. This information tells you the flag needed to enable or disable the
333diagnostic, either from the command line or through <a
334href="#pragma_GCC_diagnostic">#pragma GCC diagnostic</a>.</dd>
335
Chris Lattner28a43a42010-05-05 01:35:28 +0000[diff] [blame]336<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
337<dt id="opt_fdiagnostics-show-category"><b>-fdiagnostics-show-category=none/id/name</b>:
338Enable printing category information in diagnostic line.</dt>
339<dd>This option, which defaults to "none",
340controls whether or not Clang prints the category associated with a diagnostic
341when emitting it. Each diagnostic may or many not have an associated category,
342if it has one, it is listed in the diagnostic categorization field of the
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]343diagnostic line (in the []'s).
Chris Lattner28a43a42010-05-05 01:35:28 +0000[diff] [blame]344
345<p>For example, a format string warning will produce these three renditions
346based on the setting of this option:</p>
347
348<pre>
349 t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int' [-Wformat]
350 t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int' [-Wformat<b>,1</b>]
351 t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int' [-Wformat<b>,Format String</b>]
352</pre>
353
354<p>This category can be used by clients that want to group diagnostics by
355category, so it should be a high level category. We want dozens of these, not
356hundreds or thousands of them.</p>
357</dd>
358
359
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]360
361<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
362<dt id="opt_fdiagnostics-fixit-info"><b>-f[no-]diagnostics-fixit-info</b>:
363Enable "FixIt" information in the diagnostics output.</dt>
364<dd>This option, which defaults to on, controls whether or not Clang prints the
365information on how to fix a specific diagnostic underneath it when it knows.
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]366For example, in this output:
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]367
368<pre>
369 test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens]
370 #endif bad
371 ^
372 //
373</pre>
374
375<p>Passing <b>-fno-diagnostics-fixit-info</b> will prevent Clang from printing
376the "//" line at the end of the message. This information is useful for users
377who may not understand what is wrong, but can be confusing for machine
378parsing.</p>
379</dd>
380
381<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
Chris Lattner2a9cc232009-04-21 05:35:32 +0000[diff] [blame]382<dt id="opt_fdiagnostics-print-source-range-info">
383<b>-f[no-]diagnostics-print-source-range-info</b>:
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]384Print machine parsable information about source ranges.</dt>
385<dd>This option, which defaults to off, controls whether or not Clang prints
386information about source ranges in a machine parsable format after the
387file/line/column number information. The information is a simple sequence of
388brace enclosed ranges, where each range lists the start and end line/column
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]389locations. For example, in this output:
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]390
391<pre>
392exprs.c:47:15:{47:8-47:14}{47:17-47:24}: error: invalid operands to binary expression ('int *' and '_Complex float')
393 P = (P-42) + Gamma*4;
394 ~~~~~~ ^ ~~~~~~~
395</pre>
396
Chris Lattner2a9cc232009-04-21 05:35:32 +0000[diff] [blame]397<p>The {}'s are generated by -fdiagnostics-print-source-range-info.</p>
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]398</dd>
399
Douglas Gregor4786c152010-08-19 20:24:43 +0000[diff] [blame]400<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
401<dt id="opt_fdiagnostics-parseable-fixits">
402<b>-fdiagnostics-parseable-fixits</b>:
403Print Fix-Its in a machine parseable form.</dt>
404<dd><p>This option makes Clang print available Fix-Its in a machine parseable format at the end of diagnostics. The following example illustrates the format:</p>
405
406<pre>
Douglas Gregorbf5e09d2010-08-20 03:17:33 +0000[diff] [blame]407 fix-it:"t.cpp":{7:25-7:29}:"Gamma"
Douglas Gregor4786c152010-08-19 20:24:43 +0000[diff] [blame]408</pre>
409
NAKAMURA Takumi44626362011-04-05 00:57:02 +0000[diff] [blame]410<p>The range printed is a half-open range, so in this example the characters at
411column 25 up to but not including column 29 on line 7 in t.cpp should be
412replaced with the string &quot;Gamma&quot;. Either the range or the replacement
413string may be empty (representing strict insertions and strict erasures,
414respectively). Both the file name and the insertion string escape backslash (as
415&quot;\\&quot;), tabs (as &quot;\t&quot;), newlines (as &quot;\n&quot;), double
416quotes(as &quot;\&quot;&quot;) and non-printable characters (as octal
417&quot;\xxx&quot;).</p>
Douglas Gregor4786c152010-08-19 20:24:43 +0000[diff] [blame]418</dd>
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]419
Richard Trieue59331a2012-06-27 02:00:20 +0000[diff] [blame]420<dt id="opt_fno-elide-type">
421<b>-fno-elide-type</b>:
422Turns off elision in template type printing.</td>
423<dd><p>The default for template type printing is to elide as many template
424arguments as possible, removing those which are the same in both template types,
425leaving only the differences. Adding this flag will print all the template
426arguments. If supported by the terminal, highlighting will still appear on
427differing arguments.</p>
428
429Default:
430<pre>
431t.cc:4:5: <span class="note">note</span>: candidate function not viable: no known conversion from 'vector&lt;map&lt;[...], map&lt;<span class="template-highlight">float</span>, [...]&gt;&gt;&gt;' to 'vector&lt;map&lt;[...], map&lt;<span class="template-highlight">double</span>, [...]&gt;&gt;&gt;' for 1st argument;
432</pre>
433-fno-elide-type:
434<pre>
435t.cc:4:5: <span class="note">note</span>: candidate function not viable: no known conversion from 'vector&lt;map&lt;int, map&lt;<span class="template-highlight">float</span>, int&gt;&gt;&gt;' to 'vector&lt;map&lt;int, map&lt;<span class="template-highlight">double</span>, int&gt;&gt;&gt;' for 1st argument;
436</pre>
437</dd>
438
439<dt id="opt_fdiagnostics-show-template-tree">
440<b>-fdiagnostics-show-template-tree</b>:
441Template type diffing prints a text tree.</td>
442<dd><p>For diffing large templated types, this option will cause Clang to
443display the templates as an indented text tree, one argument per line, with
444differences marked inline. This is compatible with -fno-elide-type.</p>
445
446Default:
447<pre>
448t.cc:4:5: <span class="note">note</span>: candidate function not viable: no known conversion from 'vector&lt;map&lt;[...], map&lt;<span class="template-highlight">float</span>, [...]&gt;&gt;&gt;' to 'vector&lt;map&lt;[...], map&lt;<span class="template-highlight">double</span>, [...]&gt;&gt;&gt;' for 1st argument;
449</pre>
450-fdiagnostics-show-template-tree
451<pre>
452t.cc:4:5: <span class="note">note</span>: candidate function not viable: no known conversion for 1st argument;
453 vector&lt;
454 map&lt;
455 [...],
456 map&lt;
457 [<span class="template-highlight">float</span> != <span class="template-highlight">float</span>],
458 [...]&gt;&gt;&gt;
459</pre>
460</dd>
461
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]462</dl>
463
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]464
465
466<!-- ===================================================== -->
467<h4 id="cl_diag_warning_groups">Individual Warning Groups</h4>
468<!-- ===================================================== -->
469
470<p>TODO: Generate this from tblgen. Define one anchor per warning group.</p>
471
472
473<dl>
474
475
476<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
477<dt id="opt_Wextra-tokens"><b>-Wextra-tokens</b>: Warn about excess tokens at
478 the end of a preprocessor directive.</dt>
479<dd>This option, which defaults to on, enables warnings about extra tokens at
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]480the end of preprocessor directives. For example:
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]481
482<pre>
483 test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens]
484 #endif bad
485 ^
486</pre>
487
488<p>These extra tokens are not strictly conforming, and are usually best handled
489by commenting them out.</p>
490
491<p>This option is also enabled by <a href="">-Wfoo</a>, <a href="">-Wbar</a>,
492 and <a href="">-Wbaz</a>.</p>
493</dd>
494
Jeffrey Yasskin21d07e42010-06-05 01:39:57 +0000[diff] [blame]495<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
496<dt id="opt_Wambiguous-member-template"><b>-Wambiguous-member-template</b>:
497Warn about unqualified uses of a member template whose name resolves
498to another template at the location of the use.</dt>
499<dd>This option, which defaults to on, enables a warning in the
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]500following code:
Jeffrey Yasskin21d07e42010-06-05 01:39:57 +0000[diff] [blame]501
502<pre>
503template&lt;typename T> struct set{};
504template&lt;typename T> struct trait { typedef const T& type; };
505struct Value {
506 template&lt;typename T> void set(typename trait&lt;T>::type value) {}
507};
508void foo() {
509 Value v;
510 v.set&lt;double>(3.2);
511}
512</pre>
513
514<p>C++ [basic.lookup.classref] requires this to be an error, but,
515because it's hard to work around, Clang downgrades it to a warning as
516an extension.</p>
517</dd>
518
Jeffrey Yasskin57d12fd2010-06-07 15:58:05 +0000[diff] [blame]519<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
520<dt id="opt_Wbind-to-temporary-copy"><b>-Wbind-to-temporary-copy</b>: Warn about
521an unusable copy constructor when binding a reference to a temporary.</dt>
522<dd>This option, which defaults to on, enables warnings about binding a
523reference to a temporary when the temporary doesn't have a usable copy
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]524constructor. For example:
Jeffrey Yasskin57d12fd2010-06-07 15:58:05 +0000[diff] [blame]525
526<pre>
527 struct NonCopyable {
528 NonCopyable();
529 private:
530 NonCopyable(const NonCopyable&);
531 };
532 void foo(const NonCopyable&);
533 void bar() {
David Blaikie5090e9f2011-10-18 05:49:30 +0000[diff] [blame]534 foo(NonCopyable()); // Disallowed in C++98; allowed in C++11.
Jeffrey Yasskin57d12fd2010-06-07 15:58:05 +0000[diff] [blame]535 }
536</pre>
537<pre>
538 struct NonCopyable2 {
539 NonCopyable2();
540 NonCopyable2(NonCopyable2&);
541 };
542 void foo(const NonCopyable2&);
543 void bar() {
David Blaikie5090e9f2011-10-18 05:49:30 +0000[diff] [blame]544 foo(NonCopyable2()); // Disallowed in C++98; allowed in C++11.
Jeffrey Yasskin57d12fd2010-06-07 15:58:05 +0000[diff] [blame]545 }
546</pre>
547
548<p>Note that if <tt>NonCopyable2::NonCopyable2()</tt> has a default
549argument whose instantiation produces a compile error, that error will
550still be a hard error in C++98 mode even if this warning is turned
551off.</p>
552
553</dd>
554
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]555</dl>
556
Chad Rosiercd376a12012-02-22 20:26:10 +0000[diff] [blame]557<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
558<h3 id="cl_crash_diagnostics">Options to Control Clang Crash Diagnostics</h3>
559<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
560
561<p>As unbelievable as it may sound, Clang does crash from time to time.
562Generally, this only occurs to those living on the
563<a href="http://llvm.org/releases/download.html#svn">bleeding edge</a>. Clang
564goes to great lengths to assist you in filing a bug report. Specifically, Clang
565generates preprocessed source file(s) and associated run script(s) upon a
566crash. These files should be attached to a bug report to ease reproducibility
567of the failure. Below are the command line options to control the crash
568diagnostics.
569</p>
570
571<p><b>-fno-crash-diagnostics</b>: Disable auto-generation of preprocessed
572source files during a clang crash.</p>
573
574<p>The -fno-crash-diagnostics flag can be helpful for speeding the process of
575generating a delta reduced test case.</p>
576
577
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]578<!-- ======================================================================= -->
579<h2 id="general_features">Language and Target-Independent Features</h2>
580<!-- ======================================================================= -->
581
582
583<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
584<h3 id="diagnostics">Controlling Errors and Warnings</h3>
585<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
586
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]587<p>Clang provides a number of ways to control which code constructs cause it to
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]588emit errors and warning messages, and how they are displayed to the console.</p>
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]589
Chris Lattner3401cf82009-07-12 21:22:10 +0000[diff] [blame]590<h4 id="diagnostics_display">Controlling How Clang Displays Diagnostics</h4>
Chris Lattner65a795b2009-04-20 06:00:23 +0000[diff] [blame]591
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]592<p>When Clang emits a diagnostic, it includes rich information in the output,
593and gives you fine-grain control over which information is printed. Clang has
594the ability to print this information, and these are the options that control
595it:</p>
596
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]597<ol>
598<li>A file/line/column indicator that shows exactly where the diagnostic occurs
599 in your code [<a href="#opt_fshow-column">-fshow-column</a>, <a
600 href="#opt_fshow-source-location">-fshow-source-location</a>].</li>
601<li>A categorization of the diagnostic as a note, warning, error, or fatal
602 error.</li>
603<li>A text string that describes what the problem is.</li>
604<li>An option that indicates how to control the diagnostic (for diagnostics that
605 support it) [<a
606 href="#opt_fdiagnostics-show-option">-fdiagnostics-show-option</a>].</li>
Chris Lattner3f145382010-05-24 21:35:18 +0000[diff] [blame]607<li>A <a href="#diagnostics_categories">high-level category</a> for the
608 diagnostic for clients that want to group diagnostics by class (for
609 diagnostics that support it) [<a
Chris Lattner28a43a42010-05-05 01:35:28 +0000[diff] [blame]610 href="#opt_fdiagnostics-show-category">-fdiagnostics-show-category</a>].</li>
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]611<li>The line of source code that the issue occurs on, along with a caret and
612 ranges that indicate the important locations [<a
613 href="opt_fcaret-diagnostics">-fcaret-diagnostics</a>].</li>
614<li>"FixIt" information, which is a concise explanation of how to fix the
615 problem (when Clang is certain it knows) [<a
616 href="opt_fdiagnostics-fixit-info">-fdiagnostics-fixit-info</a>].</li>
617<li>A machine-parsable representation of the ranges involved (off by
618 default) [<a
Chris Lattner2a9cc232009-04-21 05:35:32 +0000[diff] [blame]619 href="opt_fdiagnostics-print-source-range-info">-fdiagnostics-print-source-range-info</a>].</li>
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]620</ol>
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]621
622<p>For more information please see <a href="#cl_diag_formatting">Formatting of
623Diagnostics</a>.</p>
624
Chris Lattner3f145382010-05-24 21:35:18 +0000[diff] [blame]625
Chris Lattner3401cf82009-07-12 21:22:10 +0000[diff] [blame]626<h4 id="diagnostics_mappings">Diagnostic Mappings</h4>
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]627
Chris Lattner3401cf82009-07-12 21:22:10 +0000[diff] [blame]628<p>All diagnostics are mapped into one of these 5 classes:</p>
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]629
Chris Lattner3401cf82009-07-12 21:22:10 +0000[diff] [blame]630<ul>
631<li>Ignored</li>
632<li>Note</li>
633<li>Warning</li>
634<li>Error</li>
635<li>Fatal</li>
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]636</ul>
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]637
Chris Lattner3f145382010-05-24 21:35:18 +0000[diff] [blame]638<h4 id="diagnostics_categories">Diagnostic Categories</h4>
639
640<p>Though not shown by default, diagnostics may each be associated with a
641 high-level category. This category is intended to make it possible to triage
642 builds that produce a large number of errors or warnings in a grouped way.
643</p>
644
645<p>Categories are not shown by default, but they can be turned on with the
646<a href="#opt_fdiagnostics-show-category">-fdiagnostics-show-category</a> option.
647When set to "<tt>name</tt>", the category is printed textually in the diagnostic
648output. When it is set to "<tt>id</tt>", a category number is printed. The
649mapping of category names to category id's can be obtained by running '<tt>clang
650 --print-diagnostic-categories</tt>'.
651</p>
652
653<h4 id="diagnostics_commandline">Controlling Diagnostics via Command Line
654 Flags</h4>
Chris Lattner8217f4e2009-04-20 06:26:18 +0000[diff] [blame]655
656<p>-W flags, -pedantic, etc</p>
657
Chris Lattner3401cf82009-07-12 21:22:10 +0000[diff] [blame]658<h4 id="diagnostics_pragmas">Controlling Diagnostics via Pragmas</h4>
659
660<p>Clang can also control what diagnostics are enabled through the use of
661pragmas in the source code. This is useful for turning off specific warnings
662in a section of source code. Clang supports GCC's pragma for compatibility
663with existing source code, as well as several extensions. </p>
664
665<p>The pragma may control any warning that can be used from the command line.
666Warnings may be set to ignored, warning, error, or fatal. The following
667example code will tell Clang or GCC to ignore the -Wall warnings:</p>
668
669<pre>
670#pragma GCC diagnostic ignored "-Wall"
671</pre>
672
Chris Lattnerd462b6a2011-01-24 03:47:59 +0000[diff] [blame]673<p>In addition to all of the functionality provided by GCC's pragma, Clang
Chris Lattner3401cf82009-07-12 21:22:10 +0000[diff] [blame]674also allows you to push and pop the current warning state. This is particularly
675useful when writing a header file that will be compiled by other people, because
676you don't know what warning flags they build with.</p>
677
678<p>In the below example
679-Wmultichar is ignored for only a single line of code, after which the
680diagnostics return to whatever state had previously existed.</p>
681
682<pre>
683#pragma clang diagnostic push
684#pragma clang diagnostic ignored "-Wmultichar"
685
686char b = 'df'; // no warning.
687
688#pragma clang diagnostic pop
689</pre>
690
691<p>The push and pop pragmas will save and restore the full diagnostic state of
692the compiler, regardless of how it was set. That means that it is possible to
693use push and pop around GCC compatible diagnostics and Clang will push and pop
694them appropriately, while GCC will ignore the pushes and pops as unknown
695pragmas. It should be noted that while Clang supports the GCC pragma, Clang and
696GCC do not support the exact same set of warnings, so even when using GCC
697compatible #pragmas there is no guarantee that they will have identical behaviour
698on both compilers. </p>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]699
Richard Smithf122a132012-06-13 20:27:03 +0000[diff] [blame]700<h4 id="diagnostics_systemheader">Controlling Diagnostics in System Headers</h4>
701
702<p>Warnings are suppressed when they occur in system headers. By default, an
703included file is treated as a system header if it is found in an include path
704specified by <tt>-isystem</tt>, but this can be overridden in several ways.</p>
705
706<p>The <tt>system_header</tt> pragma can be used to mark the current file as
707being a system header. No warnings will be produced from the location of the
708pragma onwards within the same file.</p>
709
710<pre>
711char a = 'xy'; // warning
712
713#pragma clang system_header
714
715char b = 'ab'; // no warning
716</pre>
717
718<p>The <tt>-isystem-prefix</tt> and <tt>-ino-system-prefix</tt> command-line
719arguments can be used to override whether subsets of an include path are treated
720as system headers. When the name in a <tt>#include</tt> directive is found
721within a header search path and starts with a system prefix, the header is
722treated as a system header. The last prefix on the command-line which matches
723the specified header name takes precedence. For instance:</p>
724
725<pre>
726clang -Ifoo -isystem bar -isystem-prefix x/ -ino-system-prefix x/y/
727</pre>
728
729<p>Here, <tt>#include "x/a.h"</tt> is treated as including a system header, even
730if the header is found in <tt>foo</tt>, and <tt>#include "x/y/b.h"</tt> is
731treated as not including a system header, even if the header is found in
732<tt>bar</tt>.
733</p>
734
735<p>A <tt>#include</tt> directive which finds a file relative to the current
736directory is treated as including a system header if the including file is
737treated as a system header.</p>
738
Ted Kremenekf391fa72011-08-18 01:17:05 +0000[diff] [blame]739<h4 id="diagnostics_enable_everything">Enabling All Warnings</h4>
740
741<p>In addition to the traditional <tt>-W</tt> flags, one can enable <b>all</b>
742 warnings by passing <tt>-Weverything</tt>.
743 This works as expected with <tt>-Werror</tt>,
744 and also includes the warnings from <tt>-pedantic</tt>.</p>
745
746<p>Note that when combined with <tt>-w</tt> (which disables all warnings), that
747 flag wins.</p>
748
Ted Kremenek2fb11eb2010-08-24 18:12:35 +0000[diff] [blame]749<h4 id="analyzer_diagnositics">Controlling Static Analyzer Diagnostics</h4>
750
751<p>While not strictly part of the compiler, the diagnostics from Clang's <a
752href="http://clang-analyzer.llvm.org">static analyzer</a> can also be influenced
Anna Zaks843f0e82012-06-16 00:30:21 +0000[diff] [blame]753by the user via changes to the source code. See the avaliable
754<a href = "http://clang-analyzer.llvm.org/annotations.html" >annotations</a> and
755the analyzer's
756<a href= "http://clang-analyzer.llvm.org/faq.html#exclude_code" >FAQ page</a> for
757more information.
Ted Kremenek2fb11eb2010-08-24 18:12:35 +0000[diff] [blame]758</ul>
759
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]760<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
761<h3 id="precompiledheaders">Precompiled Headers</h3>
762<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
763
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]764<p><a href="http://en.wikipedia.org/wiki/Precompiled_header">Precompiled
765headers</a> are a general approach employed by many compilers to reduce
766compilation time. The underlying motivation of the approach is that it is
767common for the same (and often large) header files to be included by
768multiple source files. Consequently, compile times can often be greatly improved
769by caching some of the (redundant) work done by a compiler to process headers.
770Precompiled header files, which represent one of many ways to implement
771this optimization, are literally files that represent an on-disk cache that
772contains the vital information necessary to reduce some of the work
773needed to process a corresponding header file. While details of precompiled
Chris Lattnerd462b6a2011-01-24 03:47:59 +0000[diff] [blame]774headers vary between compilers, precompiled headers have been shown to be
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]775highly effective at speeding up program compilation on systems with very large
776system headers (e.g., Mac OS/X).</p>
777
Douglas Gregorf4d59532009-06-03 22:37:00 +0000[diff] [blame]778<h4>Generating a PCH File</h4>
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]779
Douglas Gregorf4d59532009-06-03 22:37:00 +0000[diff] [blame]780<p>To generate a PCH file using Clang, one invokes Clang with
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]781the <b><tt>-x <i>&lt;language&gt;</i>-header</tt></b> option. This mirrors the
782interface in GCC for generating PCH files:</p>
783
784<pre>
785 $ gcc -x c-header test.h -o test.h.gch
Douglas Gregorf4d59532009-06-03 22:37:00 +0000[diff] [blame]786 $ clang -x c-header test.h -o test.h.pch
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]787</pre>
788
Douglas Gregorf4d59532009-06-03 22:37:00 +0000[diff] [blame]789<h4>Using a PCH File</h4>
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]790
Douglas Gregorf4d59532009-06-03 22:37:00 +0000[diff] [blame]791<p>A PCH file can then be used as a prefix header when a
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]792<b><tt>-include</tt></b> option is passed to <tt>clang</tt>:</p>
793
794<pre>
795 $ clang -include test.h test.c -o test
796</pre>
797
Douglas Gregorf4d59532009-06-03 22:37:00 +0000[diff] [blame]798<p>The <tt>clang</tt> driver will first check if a PCH file for <tt>test.h</tt>
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]799is available; if so, the contents of <tt>test.h</tt> (and the files it includes)
Douglas Gregorf4d59532009-06-03 22:37:00 +0000[diff] [blame]800will be processed from the PCH file. Otherwise, Clang falls back to
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]801directly processing the content of <tt>test.h</tt>. This mirrors the behavior of
802GCC.</p>
803
Douglas Gregorf4d59532009-06-03 22:37:00 +0000[diff] [blame]804<p><b>NOTE:</b> Clang does <em>not</em> automatically use PCH files
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]805for headers that are directly included within a source file. For example:</p>
806
807<pre>
Chris Lattnere42ec542009-06-13 20:35:58 +0000[diff] [blame]808 $ clang -x c-header test.h -o test.h.pch
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]809 $ cat test.c
810 #include "test.h"
811 $ clang test.c -o test
812</pre>
813
Douglas Gregorf4d59532009-06-03 22:37:00 +0000[diff] [blame]814<p>In this example, <tt>clang</tt> will not automatically use the PCH file for
Chris Lattner5c3074f2009-04-20 04:37:38 +0000[diff] [blame]815<tt>test.h</tt> since <tt>test.h</tt> was included directly in the source file
816and not specified on the command line using <tt>-include</tt>.</p>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]817
Douglas Gregore650c8c2009-07-07 00:12:59 +0000[diff] [blame]818<h4>Relocatable PCH Files</h4>
819<p>It is sometimes necessary to build a precompiled header from headers that
820are not yet in their final, installed locations. For example, one might build a
821precompiled header within the build tree that is then meant to be installed
822alongside the headers. Clang permits the creation of "relocatable" precompiled
823headers, which are built with a given path (into the build directory) and can
824later be used from an installed location.</p>
825
826<p>To build a relocatable precompiled header, place your headers into a
827subdirectory whose structure mimics the installed location. For example, if you
828want to build a precompiled header for the header <code>mylib.h</code> that
829will be installed into <code>/usr/include</code>, create a subdirectory
830<code>build/usr/include</code> and place the header <code>mylib.h</code> into
831that subdirectory. If <code>mylib.h</code> depends on other headers, then
832they can be stored within <code>build/usr/include</code> in a way that mimics
833the installed location.</p>
834
835<p>Building a relocatable precompiled header requires two additional arguments.
836First, pass the <code>--relocatable-pch</code> flag to indicate that the
837resulting PCH file should be relocatable. Second, pass
838<code>-isysroot /path/to/build</code>, which makes all includes for your
839library relative to the build directory. For example:</p>
840
841<pre>
842 # clang -x c-header --relocatable-pch -isysroot /path/to/build /path/to/build/mylib.h mylib.h.pch
843</pre>
844
845<p>When loading the relocatable PCH file, the various headers used in the PCH
846file are found from the system header root. For example, <code>mylib.h</code>
847can be found in <code>/usr/include/mylib.h</code>. If the headers are installed
848in some other system root, the <code>-isysroot</code> option can be used provide
849a different system root from which the headers will be based. For example,
850<code>-isysroot /Developer/SDKs/MacOSX10.4u.sdk</code> will look for
851<code>mylib.h</code> in
852<code>/Developer/SDKs/MacOSX10.4u.sdk/usr/include/mylib.h</code>.</p>
853
854<p>Relocatable precompiled headers are intended to be used in a limited number
855of cases where the compilation environment is tightly controlled and the
856precompiled header cannot be generated after headers have been installed.
857Relocatable precompiled headers also have some performance impact, because
858the difference in location between the header locations at PCH build time vs.
859at the time of PCH use requires one of the PCH optimizations,
860<code>stat()</code> caching, to be disabled. However, this change is only
861likely to affect PCH files that reference a large number of headers.</p>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]862
Mike Stump53664ca2009-12-14 23:53:10 +0000[diff] [blame]863<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
864<h3 id="codegen">Controlling Code Generation</h3>
865<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
866
867<p>Clang provides a number of ways to control code generation. The options are listed below.</p>
868
869<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]870<dl>
Mike Stump53664ca2009-12-14 23:53:10 +0000[diff] [blame]871<dt id="opt_fcatch-undefined-behavior"><b>-fcatch-undefined-behavior</b>: Turn
872on runtime code generation to check for undefined behavior.</dt>
873
874<dd>This option, which defaults to off, controls whether or not Clang
Chris Lattnerd462b6a2011-01-24 03:47:59 +0000[diff] [blame]875adds runtime checks for undefined runtime behavior. If a check fails,
Mike Stump53664ca2009-12-14 23:53:10 +0000[diff] [blame]876<tt>__builtin_trap()</tt> is used to indicate failure.
877The checks are:
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]878<ul>
Chris Lattnerd462b6a2011-01-24 03:47:59 +0000[diff] [blame]879<li>Subscripting where the static type of one operand is a variable
Mike Stump88b2a172009-12-16 03:25:12 +0000[diff] [blame]880 which is decayed from an array type and the other operand is
881 greater than the size of the array or less than zero.</li>
Mike Stump53664ca2009-12-14 23:53:10 +0000[diff] [blame]882<li>Shift operators where the amount shifted is greater or equal to the
883 promoted bit-width of the left-hand-side or less than zero.</li>
Mike Stump8f6a3ed2009-12-16 03:18:14 +0000[diff] [blame]884<li>If control flow reaches __builtin_unreachable.
885<li>When llvm implements more __builtin_object_size support, reads and
886 writes for objects that __builtin_object_size indicates we aren't
887 accessing valid memory. Bit-fields and vectors are not yet checked.
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]888</ul>
Mike Stump53664ca2009-12-14 23:53:10 +0000[diff] [blame]889</dd>
890
Kostya Serebryany48a8cd92012-03-01 23:14:19 +0000[diff] [blame]891<dt id="opt_faddress-sanitizer"><b>-f[no-]address-sanitizer</b>:
892Turn on <a href="AddressSanitizer.html">AddressSanitizer</a>,
893a memory error detector.
894
895<dt id="opt_fthread-sanitizer"><b>-f[no-]thread-sanitizer</b>:
896Turn on ThreadSanitizer, an <em>experimental</em> data race detector.
897Not ready for widespread use.
898
Nuno Lopesaa526242009-12-17 10:00:52 +0000[diff] [blame]899<dt id="opt_fno-assume-sane-operator-new"><b>-fno-assume-sane-operator-new</b>:
900Don't assume that the C++'s new operator is sane.</dt>
Nuno Lopesb23f20d2009-12-17 10:15:49 +0000[diff] [blame]901<dd>This option tells the compiler to do not assume that C++'s global new
Chris Lattnerd462b6a2011-01-24 03:47:59 +0000[diff] [blame]902operator will always return a pointer that does not
Nuno Lopesaa526242009-12-17 10:00:52 +0000[diff] [blame]903alias any other pointer when the function returns.</dd>
Evan Chengfda026b2011-04-08 22:18:01 +0000[diff] [blame]904
Evan Cheng4cf4b592011-04-08 22:34:21 +0000[diff] [blame]905<dt id="opt_ftrap-function"><b>-ftrap-function=[name]</b>: Instruct code
Evan Chengfda026b2011-04-08 22:18:01 +0000[diff] [blame]906generator to emit a function call to the specified function name for
907<tt>__builtin_trap()</tt>.</dt>
908
909<dd>LLVM code generator translates <tt>__builtin_trap()</tt> to a trap
910instruction if it is supported by the target ISA. Otherwise, the builtin is
911translated into a call to <tt>abort</tt>. If this option is set, then the code
912generator will always lower the builtin to a call to the specified function
913regardless of whether the target ISA has a trap instruction. This option is
Chris Lattner02e266b2011-04-08 22:58:43 +0000[diff] [blame]914useful for environments (e.g. deeply embedded) where a trap cannot be properly
915handled, or when some custom behavior is desired.</dd>
Hans Wennborg7bf9d9b2012-07-13 12:47:15 +0000[diff] [blame^]916
917<dt id="opt_ftls-model"><b>-ftls-model=[model]</b>: Select which TLS model to
918use.</dt>
919<dd>Valid values are: <tt>global-dynamic</tt>, <tt>local-dynamic</tt>,
920<tt>initial-exec</tt> and <tt>local-exec</tt>. The default value is
921<tt>global-dynamic</tt>. The compiler may use a different model if the selected
922model is not supported by the target, or if a more efficient model can be used.
923The TLS model can be overridden per variable using the <tt>tls_model</tt>
924attribute.
925</dd>
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]926</dl>
Nuno Lopesaa526242009-12-17 10:00:52 +0000[diff] [blame]927
Alexey Samsonov5ab52492012-05-30 06:55:10 +0000[diff] [blame]928<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
929<h3 id="debuginfosize">Controlling Size of Debug Information</h3>
930<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
931
932<p>Debug info kind generated by Clang can be set by one of the flags listed
933below. If multiple flags are present, the last one is used.</p>
934
935<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
936<dl>
937<dt id="opt_g0"><b>-g0</b>: Don't generate any debug info (default).
938
939<dt id="opt_gline-tables-only"><b>-gline-tables-only</b>:
940Generate line number tables only.
941<dd>
942This kind of debug info allows to obtain stack traces with function
943names, file names and line numbers (by such tools as
944gdb or addr2line). It doesn't contain any other data (e.g.
945description of local variables or function parameters).
946</dd>
947
948<dt id="opt_g"><b>-g</b>: Generate complete debug info.
949</dl>
950
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]951<!-- ======================================================================= -->
952<h2 id="c">C Language Features</h2>
953<!-- ======================================================================= -->
954
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]955<p>The support for standard C in clang is feature-complete except for the C99
956floating-point pragmas.</p>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]957
958<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]959<h3 id="c_ext">Extensions supported by clang</h3>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]960<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
961
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]962<p>See <a href="LanguageExtensions.html">clang language extensions</a>.</p>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]963
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]964<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
965<h3 id="c_modes">Differences between various standard modes</h3>
966<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]967
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]968<p>clang supports the -std option, which changes what language mode clang uses.
969The supported modes for C are c89, gnu89, c94, c99, gnu99 and various aliases
970for those modes. If no -std option is specified, clang defaults to gnu99 mode.
971</p>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]972
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]973<p>Differences between all c* and gnu* modes:</p>
974<ul>
975<li>c* modes define "__STRICT_ANSI__".</li>
Eli Friedman26fa0ed2009-05-27 23:02:57 +0000[diff] [blame]976<li>Target-specific defines not prefixed by underscores, like "linux", are
977defined in gnu* modes.</li>
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]978<li>Trigraphs default to being off in gnu* modes; they can be enabled by the
979-trigraphs option.</li>
980<li>The parser recognizes "asm" and "typeof" as keywords in gnu* modes; the
981variants "__asm__" and "__typeof__" are recognized in all modes.</li>
Eli Friedmanb0ac5452009-05-16 23:17:30 +0000[diff] [blame]982<li>The Apple "blocks" extension is recognized by default in gnu* modes
983on some platforms; it can be enabled in any mode with the "-fblocks"
984option.</li>
Chris Lattner741be6a2011-06-15 00:41:40 +0000[diff] [blame]985<li>Arrays that are VLA's according to the standard, but which can be constant
986 folded by the frontend are treated as fixed size arrays. This occurs for
987 things like "int X[(1, 2)];", which is technically a VLA. c* modes are
988 strictly compliant and treat these as VLAs.</li>
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]989</ul>
990
991<p>Differences between *89 and *99 modes:</p>
992<ul>
993<li>The *99 modes default to implementing "inline" as specified in C99, while
994the *89 modes implement the GNU version. This can be overridden for individual
995functions with the __gnu_inline__ attribute.</li>
Eli Friedman26fa0ed2009-05-27 23:02:57 +0000[diff] [blame]996<li>Digraphs are not recognized in c89 mode.</li>
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]997<li>The scope of names defined inside a "for", "if", "switch", "while", or "do"
998statement is different. (example: "if ((struct x {int x;}*)0) {}".)</li>
999<li>__STDC_VERSION__ is not defined in *89 modes.</li>
Eli Friedman26fa0ed2009-05-27 23:02:57 +0000[diff] [blame]1000<li>"inline" is not recognized as a keyword in c89 mode.</li>
1001<li>"restrict" is not recognized as a keyword in *89 modes.</li>
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1002<li>Commas are allowed in integer constant expressions in *99 modes.</li>
1003<li>Arrays which are not lvalues are not implicitly promoted to pointers in
1004*89 modes.</li>
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1005<li>Some warnings are different.</li>
1006</ul>
1007
1008<p>c94 mode is identical to c89 mode except that digraphs are enabled in
1009c94 mode (FIXME: And __STDC_VERSION__ should be defined!).</p>
1010
1011<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1012<h3 id="c_unimpl_gcc">GCC extensions not implemented yet</h3>
1013<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1014
1015<p>clang tries to be compatible with gcc as much as possible, but some gcc
1016extensions are not implemented yet:</p>
1017
1018<ul>
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1019
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1020<li>clang does not support #pragma weak
Eli Friedman4da92552009-06-02 08:21:31 +0000[diff] [blame]1021(<a href="http://llvm.org/bugs/show_bug.cgi?id=3679">bug 3679</a>). Due to
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1022the uses described in the bug, this is likely to be implemented at some
1023point, at least partially.</li>
1024
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1025<li>clang does not support decimal floating point types (_Decimal32 and
1026friends) or fixed-point types (_Fract and friends); nobody has expressed
1027interest in these features yet, so it's hard to say when they will be
1028implemented.</li>
1029
1030<li>clang does not support nested functions; this is a complex feature which
1031is infrequently used, so it is unlikely to be implemented anytime soon.</li>
1032
Daniel Dunbar05fa6292009-05-12 23:12:07 +0000[diff] [blame]1033<li>clang does not support global register variables, this is unlikely
Eli Friedmanca130bd2009-06-12 20:04:25 +0000[diff] [blame]1034to be implemented soon because it requires additional LLVM backend support.
1035</li>
Daniel Dunbar05fa6292009-05-12 23:12:07 +0000[diff] [blame]1036
1037<li>clang does not support static initialization of flexible array
1038members. This appears to be a rarely used extension, but could be
1039implemented pending user demand.</li>
1040
Eli Friedmanca130bd2009-06-12 20:04:25 +0000[diff] [blame]1041<li>clang does not support __builtin_va_arg_pack/__builtin_va_arg_pack_len.
1042This is used rarely, but in some potentially interesting places, like the
1043glibc headers, so it may be implemented pending user demand. Note that
1044because clang pretends to be like GCC 4.2, and this extension was introduced
1045in 4.3, the glibc headers will not try to use this extension with clang at
1046the moment.</li>
1047
1048<li>clang does not support the gcc extension for forward-declaring function
1049parameters; this has not showed up in any real-world code yet, though, so it
1050might never be implemented.</li>
1051
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1052</ul>
1053
1054<p>This is not a complete list; if you find an unsupported extension
1055missing from this list, please send an e-mail to cfe-dev. This list
1056currently excludes C++; see <a href="#cxx">C++ Language Features</a>.
1057Also, this list does not include bugs in mostly-implemented features; please
1058see the <a href="http://llvm.org/bugs/buglist.cgi?quicksearch=product%3Aclang+component%3A-New%2BBugs%2CAST%2CBasic%2CDriver%2CHeaders%2CLLVM%2BCodeGen%2Cparser%2Cpreprocessor%2CSemantic%2BAnalyzer">
1059bug tracker</a> for known existing bugs (FIXME: Is there a section for
1060bug-reporting guidelines somewhere?).</p>
1061
1062<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1063<h3 id="c_unsupp_gcc">Intentionally unsupported GCC extensions</h3>
1064<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1065
Eli Friedman0b326002009-06-12 20:11:05 +0000[diff] [blame]1066<ul>
1067
Eli Friedman2f3fca02009-06-12 20:08:48 +0000[diff] [blame]1068<li>clang does not support the gcc extension that allows variable-length arrays
Chris Lattnerd462b6a2011-01-24 03:47:59 +0000[diff] [blame]1069in structures. This is for a few reasons: one, it is tricky
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1070to implement, two, the extension is completely undocumented, and three, the
Chris Lattnerb9d511c2010-10-28 02:20:32 +0000[diff] [blame]1071extension appears to be rarely used. Note that clang <em>does</em> support
1072flexible array members (arrays with a zero or unspecified size at the end of
1073a structure).</li>
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1074
Eli Friedmanca130bd2009-06-12 20:04:25 +0000[diff] [blame]1075<li>clang does not have an equivalent to gcc's "fold"; this means that
1076clang doesn't accept some constructs gcc might accept in contexts where a
Eli Friedman248f9732011-06-13 23:12:01 +0000[diff] [blame]1077constant expression is required, like "x-x" where x is a variable.</li>
Eli Friedmanca130bd2009-06-12 20:04:25 +0000[diff] [blame]1078
Eli Friedmanca130bd2009-06-12 20:04:25 +0000[diff] [blame]1079<li>clang does not support __builtin_apply and friends; this extension is
1080extremely obscure and difficult to implement reliably.</li>
1081
Eli Friedman0b326002009-06-12 20:11:05 +0000[diff] [blame]1082</ul>
1083
Eli Friedman660a5ac2009-04-28 18:48:34 +0000[diff] [blame]1084<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1085<h3 id="c_ms">Microsoft extensions</h3>
1086<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1087
1088<p>clang has some experimental support for extensions from
1089Microsoft Visual C++; to enable it, use the -fms-extensions command-line
Eli Friedmana1821b52009-06-08 06:21:03 +0000[diff] [blame]1090option. This is the default for Windows targets. Note that the
1091support is incomplete; enabling Microsoft extensions will silently drop
1092certain constructs (including __declspec and Microsoft-style asm statements).
1093</p>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]1094
Nico Weberd4047b32012-07-11 16:56:28 +0000[diff] [blame]1095<p>clang has a -fms-compatibility flag that makes clang accept enough
1096invalid C++ to be able to parse most Microsoft headers. This flag is enabled by
1097default for Windows targets.</p>
1098
1099<p>-fdelayed-template-parsing lets clang delay all template instantiation until
1100the end of a translation unit. This flag is enabled by default for Windows
1101targets.</p>
1102
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]1103<ul>
Douglas Gregord3b227d2010-12-14 16:21:49 +0000[diff] [blame]1104<li>clang allows setting _MSC_VER with -fmsc-version=. It defaults to 1300 which
Michael J. Spencerdae4ac42010-10-21 05:21:48 +0000[diff] [blame]1105is the same as Visual C/C++ 2003. Any number is supported and can greatly affect
1106what Windows SDK and c++stdlib headers clang can compile. This option will be
1107removed when clang supports the full set of MS extensions required for these
1108headers.</li>
1109
Daniel Dunbar05fa6292009-05-12 23:12:07 +0000[diff] [blame]1110<li>clang does not support the Microsoft extension where anonymous
Daniel Dunbar869e0542009-05-13 00:23:53 +0000[diff] [blame]1111record members can be declared using user defined typedefs.</li>
Daniel Dunbar05fa6292009-05-12 23:12:07 +0000[diff] [blame]1112
Daniel Dunbar9375ed12009-05-13 21:40:49 +0000[diff] [blame]1113<li>clang supports the Microsoft "#pragma pack" feature for
1114controlling record layout. GCC also contains support for this feature,
1115however where MSVC and GCC are incompatible clang follows the MSVC
1116definition.</li>
Nico Weberd4047b32012-07-11 16:56:28 +0000[diff] [blame]1117
1118<li>clang defaults to C++11 for Windows targets.</li>
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]1119</ul>
Daniel Dunbar9375ed12009-05-13 21:40:49 +0000[diff] [blame]1120
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]1121<!-- ======================================================================= -->
Richard Smithbdb10182011-11-21 20:54:59 +0000[diff] [blame]1122<h2 id="cxx">C++ Language Features</h2>
1123<!-- ======================================================================= -->
1124
1125<p>clang fully implements all of standard C++98 except for exported templates
1126(which were removed in C++11), and
1127<a href="http://clang.llvm.org/cxx_status.html">many C++11 features</a> are also
1128implemented.</p>
1129
1130<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1131<h3 id="cxx_implimits">Controlling implementation limits</h3>
1132<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1133
1134<p><b>-fconstexpr-depth=N</b>: Sets the limit for recursive constexpr function
1135invocations to N. The default is 512.</p>
1136
1137<p><b>-ftemplate-depth=N</b>: Sets the limit for recursively nested template
1138instantiations to N. The default is 1024.</p>
1139
1140<!-- ======================================================================= -->
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]1141<h2 id="target_features">Target-Specific Features and Limitations</h2>
1142<!-- ======================================================================= -->
1143
1144
1145<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1146<h3 id="target_arch">CPU Architectures Features and Limitations</h3>
1147<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1148
1149<!-- ======================== -->
1150<h4 id="target_arch_x86">X86</h4>
1151<!-- ======================== -->
Daniel Dunbarbcaf7aa2010-09-19 19:26:59 +0000[diff] [blame]1152
1153<p>The support for X86 (both 32-bit and 64-bit) is considered stable on Darwin
1154(Mac OS/X), Linux, FreeBSD, and Dragonfly BSD: it has been tested to correctly
1155compile many large C, C++, Objective-C, and Objective-C++ codebases.</p>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]1156
NAKAMURA Takumiddf68ff2011-04-05 04:31:31 +0000[diff] [blame]1157<p>On x86_64-mingw32, passing i128(by value) is incompatible to Microsoft x64
1158calling conversion. You might need to tweak WinX86_64ABIInfo::classify()
1159in lib/CodeGen/TargetInfo.cpp.</p>
NAKAMURA Takumia75fdb22011-04-04 15:02:41 +0000[diff] [blame]1160
Eli Friedman3b658d32009-06-08 05:12:39 +0000[diff] [blame]1161<!-- ======================== -->
1162<h4 id="target_arch_arm">ARM</h4>
1163<!-- ======================== -->
Daniel Dunbarbcaf7aa2010-09-19 19:26:59 +0000[diff] [blame]1164
1165<p>The support for ARM (specifically ARMv6 and ARMv7) is considered stable on
1166Darwin (iOS): it has been tested to correctly compile many large C, C++,
Bob Wilson4ea8dfa2011-01-10 17:55:14 +0000[diff] [blame]1167Objective-C, and Objective-C++ codebases. Clang only supports a limited number
1168of ARM architectures. It does not yet fully support ARMv5, for example.</p>
Eli Friedman3b658d32009-06-08 05:12:39 +0000[diff] [blame]1169
1170<!-- ======================== -->
1171<h4 id="target_arch_other">Other platforms</h4>
1172<!-- ======================== -->
1173clang currently contains some support for PPC and Sparc; however, significant
1174pieces of code generation are still missing, and they haven't undergone
1175significant testing.
1176
Eli Friedman3b658d32009-06-08 05:12:39 +0000[diff] [blame]1177<p>clang contains limited support for the MSP430 embedded processor, but both
1178the clang support and the LLVM backend support are highly experimental.
1179
1180<p>Other platforms are completely unsupported at the moment. Adding the
1181minimal support needed for parsing and semantic analysis on a new platform
1182is quite easy; see lib/Basic/Targets.cpp in the clang source tree. This level
1183of support is also sufficient for conversion to LLVM IR for simple programs.
1184Proper support for conversion to LLVM IR requires adding code to
1185lib/CodeGen/CGCall.cpp at the moment; this is likely to change soon, though.
1186Generating assembly requires a suitable LLVM backend.
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]1187
1188<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1189<h3 id="target_os">Operating System Features and Limitations</h3>
1190<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
1191
1192<!-- ======================================= -->
1193<h4 id="target_os_darwin">Darwin (Mac OS/X)</h4>
1194<!-- ======================================= -->
1195
Chris Lattner396663b2012-05-04 21:11:08 +0000[diff] [blame]1196<p>None</p>
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]1197
NAKAMURA Takumia75fdb22011-04-04 15:02:41 +0000[diff] [blame]1198<!-- ======================================= -->
1199<h4 id="target_os_win32">Windows</h4>
1200<!-- ======================================= -->
1201
1202<p>Experimental supports are on Cygming.</p>
1203
Nico Weberd4047b32012-07-11 16:56:28 +0000[diff] [blame]1204<p>See also <a href="#c_ms">Microsoft Extensions</a>.</p>
1205
NAKAMURA Takumia75fdb22011-04-04 15:02:41 +0000[diff] [blame]1206<h5>Cygwin</h5>
1207
1208<p>Clang works on Cygwin-1.7.</p>
1209
1210<h5>MinGW32</h5>
1211
1212<p>Clang works on some mingw32 distributions.
1213Clang assumes directories as below;</p>
1214
1215<ul>
1216<li><tt>C:/mingw/include</tt></li>
1217<li><tt>C:/mingw/lib</tt></li>
1218<li><tt>C:/mingw/lib/gcc/mingw32/4.[3-5].0/include/c++</tt></li>
1219</ul>
1220
NAKAMURA Takumi0e53df62011-11-17 07:54:13 +0000[diff] [blame]1221<p>On MSYS, a few tests might fail.</p>
NAKAMURA Takumia75fdb22011-04-04 15:02:41 +0000[diff] [blame]1222
1223<h5>MinGW-w64</h5>
1224
Douglas Gregordad879a2011-08-30 00:40:12 +0000[diff] [blame]1225<p>For 32-bit (i686-w64-mingw32), and 64-bit (x86_64-w64-mingw32), Clang assumes as below;<p>
NAKAMURA Takumia75fdb22011-04-04 15:02:41 +0000[diff] [blame]1226
1227<ul>
Douglas Gregordad879a2011-08-30 00:40:12 +0000[diff] [blame]1228<li><tt>GCC versions 4.5.0 to 4.5.3, 4.6.0 to 4.6.2, or 4.7.0 (for the C++ header search path)</tt></li>
1229<li><tt>some_directory/bin/gcc.exe</tt></li>
1230<li><tt>some_directory/bin/clang.exe</tt></li>
1231<li><tt>some_directory/bin/clang++.exe</tt></li>
1232<li><tt>some_directory/bin/../include/c++/GCC_version</tt></li>
1233<li><tt>some_directory/bin/../include/c++/GCC_version/x86_64-w64-mingw32</tt></li>
1234<li><tt>some_directory/bin/../include/c++/GCC_version/i686-w64-mingw32</tt></li>
1235<li><tt>some_directory/bin/../include/c++/GCC_version/backward</tt></li>
1236<li><tt>some_directory/bin/../x86_64-w64-mingw32/include</tt></li>
1237<li><tt>some_directory/bin/../i686-w64-mingw32/include</tt></li>
1238<li><tt>some_directory/bin/../include</tt></li>
NAKAMURA Takumia75fdb22011-04-04 15:02:41 +0000[diff] [blame]1239</ul>
1240
David Blaikiea9639622012-04-19 17:21:46 +0000[diff] [blame]1241<p>This directory layout is standard for any toolchain you will find on the official <a href="http://mingw-w64.sourceforge.net">MinGW-w64 website</a>.
Douglas Gregordad879a2011-08-30 00:40:12 +0000[diff] [blame]1242
1243<p>Clang expects the GCC executable &quot;gcc.exe&quot; compiled for i686-w64-mingw32 (or x86_64-w64-mingw32) to be present on PATH.</p>
1244
1245<p><a href="http://llvm.org/bugs/show_bug.cgi?id=9072">Some tests might fail</a>
1246on x86_64-w64-mingw32.</p>
NAKAMURA Takumia75fdb22011-04-04 15:02:41 +0000[diff] [blame]1247
Chris Lattnercf17d9d2009-04-20 04:23:09 +0000[diff] [blame]1248</div>
1249</body>
1250</html>