diff options
Diffstat (limited to 'docs/UsersManual.html')
| -rw-r--r-- | docs/UsersManual.html | 688 |
1 files changed, 688 insertions, 0 deletions
diff --git a/docs/UsersManual.html b/docs/UsersManual.html new file mode 100644 index 0000000..3f48c4abe --- /dev/null +++ b/docs/UsersManual.html @@ -0,0 +1,688 @@ +<html> +<head> +<title>Clang Compiler User's Manual</title> +<link type="text/css" rel="stylesheet" href="../menu.css" /> +<link type="text/css" rel="stylesheet" href="../content.css" /> +<style type="text/css"> +td { + vertical-align: top; +} +</style> +</head> +<body> + +<!--#include virtual="../menu.html.incl"--> + +<div id="content"> + +<h1>Clang Compiler User's Manual</h1> + +<ul> +<li><a href="#intro">Introduction</a> + <ul> + <li><a href="#terminology">Terminology</a></li> + <li><a href="#basicusage">Basic Usage</a></li> + </ul> +</li> +<li><a href="#commandline">Command Line Options</a> + <ul> + <li><a href="#cl_diagnostics">Options to Control Error and Warning + Messages</a></li> + </ul> +</li> +<li><a href="#general_features">Language and Target-Independent Features</a> + <ul> + <li><a href="#diagnostics">Controlling Errors and Warnings</a></li> + <li><a href="#precompiledheaders">Precompiled Headers</a></li> + </ul> +</li> +<li><a href="#c">C Language Features</a> + <ul> + <li><a href="#c_ext">Extensions supported by clang</a></li> + <li><a href="#c_modes">Differences between various standard modes</a></li> + <li><a href="#c_unimpl_gcc">GCC extensions not implemented yet</a></li> + <li><a href="#c_unsupp_gcc">Intentionally unsupported GCC extensions</a></li> + <li><a href="#c_ms">Microsoft extensions</a></li> + </ul> +</li> +<li><a href="#objc">Objective-C Language Features</a> + <ul> + <li><a href="#objc_incompatibilities">Intentional Incompatibilities with + GCC</a></li> + </ul> +</li> +<li><a href="#cxx">C++ Language Features</a> + <ul> + <li>...</li> + </ul> +</li> +<li><a href="#objcxx">Objective C++ Language Features</a> + <ul> + <li>...</li> + </ul> +</li> +<li><a href="#target_features">Target-Specific Features and Limitations</a> + <ul> + <li><a href="#target_arch">CPU Architectures Features and Limitations</a> + <ul> + <li><a href="#target_arch_x86">X86</a></li> + <li>PPC</li> + <li>ARM</li> + </ul> + </li> + <li><a href="#target_os">Operating System Features and Limitations</a> + <ul> + <li><a href="#target_os_darwin">Darwin (Mac OS/X)</a></li> + <li>Linux, etc.</li> + </ul> + + </li> + </ul> +</li> +</ul> + + +<!-- ======================================================================= --> +<h2 id="intro">Introduction</h2> +<!-- ======================================================================= --> + +<p>The Clang Compiler is an open-source compiler for the C family of programming +languages, aiming to be the best in class implementation of these languages. +Clang builds on the LLVM optimizer and code generator, allowing it to provide +high-quality optimization and code generation support for many targets. For +more general information, please see the <a href="http://clang.llvm.org">Clang +Web Site</a> or the <a href="http://llvm.org">LLVM Web Site</a>.</p> + +<p>This document describes important notes about using Clang as a compiler for +an end-user, documenting the supported features, command line options, etc. If +you are interested in using Clang to build a tool that processes code, please +see <a href="InternalsManual.html">the Clang Internals Manual</a>. If you are +interested in the <a href="http://clang.llvm.org/StaticAnalysis.html">Clang +Static Analyzer</a>, please see its web page.</p> + +<p>Clang is designed to support the C family of programming languages, which +includes <a href="#c">C</a>, <a href="#objc">Objective-C</a>, <a +href="#cxx">C++</a>, and <a href="#objcxx">Objective-C++</a> as well as many +dialects of those. For language-specific information, please see the +corresponding language specific section:</p> + +<ul> +<li><a href="#c">C Language</a>: K&R C, ANSI C89, ISO C90, ISO C94 + (C89+AMD1), ISO C99 (+TC1, TC2, TC3). </li> +<li><a href="#objc">Objective-C Language</a>: ObjC 1, ObjC 2, ObjC 2.1, plus + variants depending on base language.</li> +<li><a href="#cxx">C++ Language Features</a></li> +<li><a href="#objcxx">Objective C++ Language</a></li> +</ul> + +<p>In addition to these base languages and their dialects, Clang supports a +broad variety of language extensions, which are documented in the corresponding +language section. These extensions are provided to be compatible with the GCC, +Microsoft, and other popular compilers as well as to improve functionality +through Clang-specific features. The Clang driver and language features are +intentionally designed to be as compatible with the GNU GCC compiler as +reasonably possible, easing migration from GCC to Clang. In most cases, code +"just works".</p> + +<p>In addition to language specific features, Clang has a variety of features +that depend on what CPU architecture or operating system is being compiled for. +Please see the <a href="target_features">Target-Specific Features and +Limitations</a> section for more details.</p> + +<p>The rest of the introduction introduces some basic <a +href="#terminology">compiler terminology</a> that is used throughout this manual +and contains a basic <a href="#basicusage">introduction to using Clang</a> +as a command line compiler.</p> + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="terminology">Terminology</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p>Front end, parser, backend, preprocessor, undefined behavior, diagnostic, + optimizer</p> + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="basicusage">Basic Usage</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p>Intro to how to use a C compiler for newbies.</p> +<p> +compile + link + +compile then link + +debug info + +enabling optimizations + +picking a language to use, defaults to C99 by default. Autosenses based on +extension. + +using a makefile +</p> + + +<!-- ======================================================================= --> +<h2 id="commandline">Command Line Options</h2> +<!-- ======================================================================= --> + +<p> +This section is generally an index into other sections. It does not go into +depth on the ones that are covered by other sections. However, the first part +introduces the language selection and other high level options like -c, -g, etc. +</p> + + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="cl_diagnostics">Options to Control Error and Warning Messages</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p><b>-Werror</b>: Turn warnings into errors.</p> +<p><b>-Werror=foo</b>: Turn warning "foo" into an error.</p> +<p><b>-Wno-error=foo</b>: Turn warning "foo" into an warning even if -Werror is + specified.</p> +<p><b>-Wfoo</b>: Enable warning foo</p> +<p><b>-Wno-foo</b>: Disable warning foo</p> +<p><b>-w</b>: Disable all warnings.</p> +<p><b>-pedantic</b>: Warn on language extensions.</p> +<p><b>-pedantic-errors</b>: Error on language extensions.</p> +<p><b>-Wsystem-headers</b>: Enable warnings from system headers.</p> + +<!-- ================================================= --> +<h4 id="cl_diag_formatting">Formatting of Diagnostics</h4> +<!-- ================================================= --> + +<p>Clang aims to produce beautiful diagnostics by default, particularly for new +users that first come to Clang. However, different people have different +preferences, and sometimes Clang is driven by another program that wants to +parse simple and consistent output, not a person. For these cases, Clang +provides a wide range of options to control the exact output format of the +diagnostics that it generates.</p> + +<dl> + +<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> +<dt id="opt_fshow-column"><b>-f[no-]show-column</b>: Print column number in +diagnostic.</dt> +<dd>This option, which defaults to on, controls whether or not Clang prints the +column number of a diagnostic. For example, when this is enabled, Clang will +print something like:</p> + +<pre> + test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens] + #endif bad + ^ + // +</pre> + +<p>When this is disabled, Clang will print "test.c:28: warning..." with no +column number.</p> +</dd> + +<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> +<dt id="opt_fshow-source-location"><b>-f[no-]show-source-location</b>: Print +source file/line/column information in diagnostic.</dt> +<dd>This option, which defaults to on, controls whether or not Clang prints the +filename, line number and column number of a diagnostic. For example, +when this is enabled, Clang will print something like:</p> + +<pre> + test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens] + #endif bad + ^ + // +</pre> + +<p>When this is disabled, Clang will not print the "test.c:28:8: " part.</p> +</dd> + +<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> +<dt id="opt_fcaret-diagnostics"><b>-f[no-]caret-diagnostics</b>: Print source +line and ranges from source code in diagnostic.</dt> +<dd>This option, which defaults to on, controls whether or not Clang prints the +source line, source ranges, and caret when emitting a diagnostic. For example, +when this is enabled, Clang will print something like:</p> + +<pre> + test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens] + #endif bad + ^ + // +</pre> + +<p>When this is disabled, Clang will just print:</p> + +<pre> + test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens] +</pre> + +</dd> + +<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> +<dt id="opt_fdiagnostics-show-option"><b>-f[no-]diagnostics-show-option</b>: +Enable <tt>[-Woption]</tt> information in diagnostic line.</dt> +<dd>This option, which defaults to on, +controls whether or not Clang prints the associated <A +href="#cl_diag_warning_groups">warning group</a> option name when outputting +a warning diagnostic. For example, in this output:</p> + +<pre> + test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens] + #endif bad + ^ + // +</pre> + +<p>Passing <b>-fno-diagnostics-show-option</b> will prevent Clang from printing +the [<a href="#opt_Wextra-tokens">-Wextra-tokens</a>] information in the +diagnostic. This information tells you the flag needed to enable or disable the +diagnostic, either from the command line or through <a +href="#pragma_GCC_diagnostic">#pragma GCC diagnostic</a>.</dd> + + +<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> +<dt id="opt_fdiagnostics-fixit-info"><b>-f[no-]diagnostics-fixit-info</b>: +Enable "FixIt" information in the diagnostics output.</dt> +<dd>This option, which defaults to on, controls whether or not Clang prints the +information on how to fix a specific diagnostic underneath it when it knows. +For example, in this output:</p> + +<pre> + test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens] + #endif bad + ^ + // +</pre> + +<p>Passing <b>-fno-diagnostics-fixit-info</b> will prevent Clang from printing +the "//" line at the end of the message. This information is useful for users +who may not understand what is wrong, but can be confusing for machine +parsing.</p> +</dd> + +<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> +<dt id="opt_fdiagnostics-print-source-range-info"> +<b>-f[no-]diagnostics-print-source-range-info</b>: +Print machine parsable information about source ranges.</dt> +<dd>This option, which defaults to off, controls whether or not Clang prints +information about source ranges in a machine parsable format after the +file/line/column number information. The information is a simple sequence of +brace enclosed ranges, where each range lists the start and end line/column +locations. For example, in this output:</p> + +<pre> +exprs.c:47:15:{47:8-47:14}{47:17-47:24}: error: invalid operands to binary expression ('int *' and '_Complex float') + P = (P-42) + Gamma*4; + ~~~~~~ ^ ~~~~~~~ +</pre> + +<p>The {}'s are generated by -fdiagnostics-print-source-range-info.</p> +</dd> + + +</dl> + + + + +<!-- ===================================================== --> +<h4 id="cl_diag_warning_groups">Individual Warning Groups</h4> +<!-- ===================================================== --> + +<p>TODO: Generate this from tblgen. Define one anchor per warning group.</p> + + +<dl> + + +<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> +<dt id="opt_Wextra-tokens"><b>-Wextra-tokens</b>: Warn about excess tokens at + the end of a preprocessor directive.</dt> +<dd>This option, which defaults to on, enables warnings about extra tokens at +the end of preprocessor directives. For example:</p> + +<pre> + test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens] + #endif bad + ^ +</pre> + +<p>These extra tokens are not strictly conforming, and are usually best handled +by commenting them out.</p> + +<p>This option is also enabled by <a href="">-Wfoo</a>, <a href="">-Wbar</a>, + and <a href="">-Wbaz</a>.</p> +</dd> + +</dl> + +<!-- ======================================================================= --> +<h2 id="general_features">Language and Target-Independent Features</h2> +<!-- ======================================================================= --> + + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="diagnostics">Controlling Errors and Warnings</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p>Clang provides a number of ways to control which code constructs cause it to +emit errors and warning messages, and how they are displayed to the console.</p> + +<h4>Controlling How Clang Displays Diagnostics</h4> + +<p>When Clang emits a diagnostic, it includes rich information in the output, +and gives you fine-grain control over which information is printed. Clang has +the ability to print this information, and these are the options that control +it:</p> + +<p> +<ol> +<li>A file/line/column indicator that shows exactly where the diagnostic occurs + in your code [<a href="#opt_fshow-column">-fshow-column</a>, <a + href="#opt_fshow-source-location">-fshow-source-location</a>].</li> +<li>A categorization of the diagnostic as a note, warning, error, or fatal + error.</li> +<li>A text string that describes what the problem is.</li> +<li>An option that indicates how to control the diagnostic (for diagnostics that + support it) [<a + href="#opt_fdiagnostics-show-option">-fdiagnostics-show-option</a>].</li> +<li>The line of source code that the issue occurs on, along with a caret and + ranges that indicate the important locations [<a + href="opt_fcaret-diagnostics">-fcaret-diagnostics</a>].</li> +<li>"FixIt" information, which is a concise explanation of how to fix the + problem (when Clang is certain it knows) [<a + href="opt_fdiagnostics-fixit-info">-fdiagnostics-fixit-info</a>].</li> +<li>A machine-parsable representation of the ranges involved (off by + default) [<a + href="opt_fdiagnostics-print-source-range-info">-fdiagnostics-print-source-range-info</a>].</li> +</ol></p> + +<p>For more information please see <a href="#cl_diag_formatting">Formatting of +Diagnostics</a>.</p> + +<h4>Controlling Which Diagnostics Clang Generates</h4> + +<p>mappings: ignore, note, warning, error, fatal</p> + +<p> +The two major classes are control from the command line and control via pragmas +in your code.</p> + + +<p>-W flags, -pedantic, etc</p> + +<p>pragma GCC diagnostic</p> + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="precompiledheaders">Precompiled Headers</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p><a href="http://en.wikipedia.org/wiki/Precompiled_header">Precompiled +headers</a> are a general approach employed by many compilers to reduce +compilation time. The underlying motivation of the approach is that it is +common for the same (and often large) header files to be included by +multiple source files. Consequently, compile times can often be greatly improved +by caching some of the (redundant) work done by a compiler to process headers. +Precompiled header files, which represent one of many ways to implement +this optimization, are literally files that represent an on-disk cache that +contains the vital information necessary to reduce some of the work +needed to process a corresponding header file. While details of precompiled +headers vary between compilers, precompiled headers have been shown to be a +highly effective at speeding up program compilation on systems with very large +system headers (e.g., Mac OS/X).</p> + +<p>Clang supports an implementation of precompiled headers known as +<em>pre-tokenized headers</em> (PTH). Clang's pre-tokenized headers support most +of same interfaces as GCC's pre-compiled headers (as well as others) but are +completely different in their implementation. If you are interested in how +PTH is implemented, please see the <a href="PTHInternals.html">PTH Internals + document</a>.</p> + +<h4>Generating a PTH File</h4> + +<p>To generate a PTH file using Clang, one invokes Clang with +the <b><tt>-x <i><language></i>-header</tt></b> option. This mirrors the +interface in GCC for generating PCH files:</p> + +<pre> + $ gcc -x c-header test.h -o test.h.gch + $ clang -x c-header test.h -o test.h.pth +</pre> + +<h4>Using a PTH File</h4> + +<p>A PTH file can then be used as a prefix header when a +<b><tt>-include</tt></b> option is passed to <tt>clang</tt>:</p> + +<pre> + $ clang -include test.h test.c -o test +</pre> + +<p>The <tt>clang</tt> driver will first check if a PTH file for <tt>test.h</tt> +is available; if so, the contents of <tt>test.h</tt> (and the files it includes) +will be processed from the PTH file. Otherwise, Clang falls back to +directly processing the content of <tt>test.h</tt>. This mirrors the behavior of +GCC.</p> + +<p><b>NOTE:</b> Clang does <em>not</em> automatically use PTH files +for headers that are directly included within a source file. For example:</p> + +<pre> + $ clang -x c-header test.h -o test.h.pth + $ cat test.c + #include "test.h" + $ clang test.c -o test +</pre> + +<p>In this example, <tt>clang</tt> will not automatically use the PTH file for +<tt>test.h</tt> since <tt>test.h</tt> was included directly in the source file +and not specified on the command line using <tt>-include</tt>.</p> + + +<!-- ======================================================================= --> +<h2 id="c">C Language Features</h2> +<!-- ======================================================================= --> + +<p>The support for standard C in clang is feature-complete except for the C99 +floating-point pragmas.</p> + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="c_ext">Extensions supported by clang</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p>See <a href="LanguageExtensions.html">clang language extensions</a>.</p> + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="c_modes">Differences between various standard modes</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p>clang supports the -std option, which changes what language mode clang uses. +The supported modes for C are c89, gnu89, c94, c99, gnu99 and various aliases +for those modes. If no -std option is specified, clang defaults to gnu99 mode. +</p> + +<p>Differences between all c* and gnu* modes:</p> +<ul> +<li>c* modes define "__STRICT_ANSI__".</li> +<li>Target-specific defines not prefixed by underscores, like "linux", are +defined in gnu* modes.</li> +<li>Trigraphs default to being off in gnu* modes; they can be enabled by the +-trigraphs option.</li> +<li>The parser recognizes "asm" and "typeof" as keywords in gnu* modes; the +variants "__asm__" and "__typeof__" are recognized in all modes.</li> +<li>The Apple "blocks" extension is recognized by default in gnu* modes +on some platforms; it can be enabled in any mode with the "-fblocks" +option.</li> +<li>Some warnings are different.</li> +</ul> + +<p>Differences between *89 and *99 modes:</p> +<ul> +<li>The *99 modes default to implementing "inline" as specified in C99, while +the *89 modes implement the GNU version. This can be overridden for individual +functions with the __gnu_inline__ attribute.</li> +<li>Digraphs are not recognized in c89 mode.</li> +<li>The scope of names defined inside a "for", "if", "switch", "while", or "do" +statement is different. (example: "if ((struct x {int x;}*)0) {}".)</li> +<li>__STDC_VERSION__ is not defined in *89 modes.</li> +<li>"inline" is not recognized as a keyword in c89 mode.</li> +<li>"restrict" is not recognized as a keyword in *89 modes.</li> +<li>Commas are allowed in integer constant expressions in *99 modes.</li> +<li>Arrays which are not lvalues are not implicitly promoted to pointers in +*89 modes.</li> +<li>Some warnings are different.</li> +</ul> + +<p>c94 mode is identical to c89 mode except that digraphs are enabled in +c94 mode (FIXME: And __STDC_VERSION__ should be defined!).</p> + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="c_unimpl_gcc">GCC extensions not implemented yet</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p>clang tries to be compatible with gcc as much as possible, but some gcc +extensions are not implemented yet:</p> + +<ul> +<li>clang does not support __label__ +(<a href="http://llvm.org/bugs/show_bug.cgi?id=3429">bug 3429</a>). This is +a relatively small feature, so it is likely to be implemented relatively +soon.</li> + +<li>clang does not support attributes on function pointers +(<a href="http://llvm.org/bugs/show_bug.cgi?id=2461">bug 2461</a>). This is +a relatively important feature, so it is likely to be implemented relatively +soon.</li> + +<li>clang does not support #pragma weak +(<a href="http://llvm.org/bugs/show_bug.cgi?id=3679">bug 3679</a>). Due to +the uses described in the bug, this is likely to be implemented at some +point, at least partially.</li> + +<li>clang does not support #pragma align +(<a href="http://llvm.org/bugs/show_bug.cgi?id=3811">bug 3811</a>). This is a +relatively small feature, so it is likely to be implemented relatively +soon.</li> + +<li>clang does not support code generation for local variables pinned to +registers (<a href="http://llvm.org/bugs/show_bug.cgi?id=3933">bug 3933</a>). +This is a relatively small feature, so it is likely to be implemented +relatively soon.</li> + +<li>clang does not support decimal floating point types (_Decimal32 and +friends) or fixed-point types (_Fract and friends); nobody has expressed +interest in these features yet, so it's hard to say when they will be +implemented.</li> + +<li>clang does not support nested functions; this is a complex feature which +is infrequently used, so it is unlikely to be implemented anytime soon.</li> + +<li>clang does not support __builtin_apply and friends; this extension requires +complex code generator support that does not currently exist in LLVM, and there +is very little demand, so it is unlikely to be implemented anytime soon.</li> + +<li>clang does not support global register variables, this is unlikely +to be implemented soon.</li> + +<li>clang does not support static initialization of flexible array +members. This appears to be a rarely used extension, but could be +implemented pending user demand.</li> + +</ul> + +<p>This is not a complete list; if you find an unsupported extension +missing from this list, please send an e-mail to cfe-dev. This list +currently excludes C++; see <a href="#cxx">C++ Language Features</a>. +Also, this list does not include bugs in mostly-implemented features; please +see 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"> +bug tracker</a> for known existing bugs (FIXME: Is there a section for +bug-reporting guidelines somewhere?).</p> + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="c_unsupp_gcc">Intentionally unsupported GCC extensions</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p>clang does not support the gcc extension that allows variable-length arrays +in structures. This is for a few of reasons: one, it is tricky +to implement, two, the extension is completely undocumented, and three, the +extension appears to be very rarely used.</p> + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="c_ms">Microsoft extensions</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p>clang has some experimental support for extensions from +Microsoft Visual C++; to enable it, use the -fms-extensions command-line +option. Eventually, this will be the default for Windows targets. +These extensions are not anywhere near complete, so please do not +file bugs; patches are welcome, though.</p> + +<li>clang does not support the Microsoft extension where anonymous +record members can be declared using user defined typedefs.</li> + +<li>clang supports the Microsoft "#pragma pack" feature for +controlling record layout. GCC also contains support for this feature, +however where MSVC and GCC are incompatible clang follows the MSVC +definition.</li> + +<!-- ======================================================================= --> +<h2 id="objc">Objective-C Language Features</h2> +<!-- ======================================================================= --> + + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="objc_incompatibilities">Intentional Incompatibilities with GCC</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<p>No cast of super, no lvalue casts.</p> + + + +<!-- ======================================================================= --> +<h2 id="cxx">C++ Language Features</h2> +<!-- ======================================================================= --> + +<p>At this point, Clang C++ is not generally useful. However, Clang C++ support +is under active development and is progressing rapidly. Please see the <a +href="http://clang.llvm.org/cxx_status.html">C++ Status</a> page for details or +ask on the mailing list about how you can help.</p> + +<p>Note that the clang driver will refuse to even try to use clang to compile +C++ code unless you pass the <tt>-ccc-clang-cxx</tt> option to the driver. If +you really want to play with Clang's C++ support, please pass that flag. </p> + +<!-- ======================================================================= --> +<h2 id="objcxx">Objective C++ Language Features</h2> +<!-- ======================================================================= --> + +<p>At this point, Clang C++ support is not generally useful (and therefore, +neither is Objective-C++). Please see the <a href="#cxx">C++ section</a> for +more information.</p> + +<!-- ======================================================================= --> +<h2 id="target_features">Target-Specific Features and Limitations</h2> +<!-- ======================================================================= --> + + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="target_arch">CPU Architectures Features and Limitations</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<!-- ======================== --> +<h4 id="target_arch_x86">X86</h4> +<!-- ======================== --> + + +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> +<h3 id="target_os">Operating System Features and Limitations</h3> +<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> + +<!-- ======================================= --> +<h4 id="target_os_darwin">Darwin (Mac OS/X)</h4> +<!-- ======================================= --> + +<p>No __thread support, 64-bit ObjC support requires SL tools.</p> + +</div> +</body> +</html> |
