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diff --git a/docs/UsersManual.html b/docs/UsersManual.html deleted file mode 100644 index 35fc5dc..0000000 --- a/docs/UsersManual.html +++ /dev/null @@ -1,1309 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" - "http://www.w3.org/TR/html4/strict.dtd"> -<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> - <li><a href="#cl_crash_diagnostics">Options to Control Clang Crash - Diagnostics</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> - <ul> - <li><a href="#diagnostics_display">Controlling How Clang Displays Diagnostics</a></li> - <li><a href="#diagnostics_mappings">Diagnostic Mappings</a></li> - <li><a href="#diagnostics_categories">Diagnostic Categories</a></li> - <li><a href="#diagnostics_commandline">Controlling Diagnostics via Command Line Flags</a></li> - <li><a href="#diagnostics_pragmas">Controlling Diagnostics via Pragmas</a></li> - <li><a href="#diagnostics_systemheader">Controlling Diagnostics in System Headers</a></li> - <li><a href="#diagnostics_enable_everything">Enabling All Warnings</a></li> - <li><a href="#analyzer_diagnositics">Controlling Static Analyzer Diagnostics</a></li> - </ul> - </li> - <li><a href="#precompiledheaders">Precompiled Headers</a></li> - <li><a href="#codegen">Controlling Code Generation</a></li> - <li><a href="#debuginfosize">Controlling Size of Debug Information</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="#cxx">C++ Language Features</a> - <ul> - <li><a href="#cxx_implimits">Controlling implementation limits</a></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><a href="#target_arch_arm">ARM</a></li> - <li><a href="#target_arch_other">Other platforms</a></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> - <li><a href="#target_os_win32">Windows</a></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-analyzer.llvm.org">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</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>-Weverything</b>: <a href="#diagnostics_enable_everything">Enable <b>all</b> warnings.</a></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> - -<p><b>-ferror-limit=123</b>: Stop emitting diagnostics after 123 errors have - been produced. The default is 20, and the error limit can be disabled with - -ferror-limit=0.</p> - -<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> - -<!-- ================================================= --> -<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: - -<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> - -<p>The printed column numbers count bytes from the beginning of the line; take -care if your source contains multibyte characters.</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: - -<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: - -<pre> - test.c:28:8: warning: extra tokens at end of #endif directive [-Wextra-tokens] - #endif bad - ^ - // -</pre> -</dd> -<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> -<dt id="opt_fcolor_diagnostics"><b>-f[no-]color-diagnostics</b>: </dt> -<dd>This option, which defaults to on when a color-capable terminal is - detected, controls whether or not Clang prints diagnostics in color. - When this option is enabled, Clang will use colors to highlight - specific parts of the diagnostic, e.g., - <pre> - <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> - #endif bad - <span style="color:green">^</span> - <span style="color:green">//</span> -</pre> - -<p>When this is disabled, Clang will just print:</p> - -<pre> - test.c:2:8: warning: extra tokens at end of #endif directive [-Wextra-tokens] - #endif bad - ^ - // -</pre> -</dd> -<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> -<dt id="opt_fdiagnostics-format"><b>-fdiagnostics-format=clang/msvc/vi</b>: -Changes diagnostic output format to better match IDEs and command line tools.</dt> -<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: - - <dl> - <dt><b>clang</b> (default)</dt> - <dd> - <pre>t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int'</pre> - </dd> - - <dt><b>msvc</b></dt> - <dd> - <pre>t.c(3,11) : warning: conversion specifies type 'char *' but the argument has type 'int'</pre> - </dd> - - <dt><b>vi</b></dt> - <dd> - <pre>t.c +3:11: warning: conversion specifies type 'char *' but the argument has type 'int'</pre> - </dd> - </dl> -</dd> - -<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> -<dt id="opt_fdiagnostics-show-name"><b>-f[no-]diagnostics-show-name</b>: -Enable the display of the diagnostic name.</dt> -<dd>This option, which defaults to off, controls whether or not -Clang prints the associated name.<p></p></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: - -<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-show-category"><b>-fdiagnostics-show-category=none/id/name</b>: -Enable printing category information in diagnostic line.</dt> -<dd>This option, which defaults to "none", -controls whether or not Clang prints the category associated with a diagnostic -when emitting it. Each diagnostic may or many not have an associated category, -if it has one, it is listed in the diagnostic categorization field of the -diagnostic line (in the []'s). - -<p>For example, a format string warning will produce these three renditions -based on the setting of this option:</p> - -<pre> - t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int' [-Wformat] - t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int' [-Wformat<b>,1</b>] - t.c:3:11: warning: conversion specifies type 'char *' but the argument has type 'int' [-Wformat<b>,Format String</b>] -</pre> - -<p>This category can be used by clients that want to group diagnostics by -category, so it should be a high level category. We want dozens of these, not -hundreds or thousands of them.</p> -</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: - -<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: - -<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> - -<p>The printed column numbers count bytes from the beginning of the line; take -care if your source contains multibyte characters.</p> -</dd> - -<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> -<dt id="opt_fdiagnostics-parseable-fixits"> -<b>-fdiagnostics-parseable-fixits</b>: -Print Fix-Its in a machine parseable form.</dt> -<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> - -<pre> - fix-it:"t.cpp":{7:25-7:29}:"Gamma" -</pre> - -<p>The range printed is a half-open range, so in this example the characters at -column 25 up to but not including column 29 on line 7 in t.cpp should be -replaced with the string "Gamma". Either the range or the replacement -string may be empty (representing strict insertions and strict erasures, -respectively). Both the file name and the insertion string escape backslash (as -"\\"), tabs (as "\t"), newlines (as "\n"), double -quotes(as "\"") and non-printable characters (as octal -"\xxx").</p> - -<p>The printed column numbers count bytes from the beginning of the line; take -care if your source contains multibyte characters.</p> -</dd> - -<dt id="opt_fno-elide-type"> -<b>-fno-elide-type</b>: -Turns off elision in template type printing.</dt> -<dd><p>The default for template type printing is to elide as many template -arguments as possible, removing those which are the same in both template types, -leaving only the differences. Adding this flag will print all the template -arguments. If supported by the terminal, highlighting will still appear on -differing arguments.</p> - -Default: -<pre> -t.cc:4:5: <span class="note">note</span>: candidate function not viable: no known conversion from 'vector<map<[...], map<<span class="template-highlight">float</span>, [...]>>>' to 'vector<map<[...], map<<span class="template-highlight">double</span>, [...]>>>' for 1st argument; -</pre> --fno-elide-type: -<pre> -t.cc:4:5: <span class="note">note</span>: candidate function not viable: no known conversion from 'vector<map<int, map<<span class="template-highlight">float</span>, int>>>' to 'vector<map<int, map<<span class="template-highlight">double</span>, int>>>' for 1st argument; -</pre> -</dd> - -<dt id="opt_fdiagnostics-show-template-tree"> -<b>-fdiagnostics-show-template-tree</b>: -Template type diffing prints a text tree.</dt> -<dd><p>For diffing large templated types, this option will cause Clang to -display the templates as an indented text tree, one argument per line, with -differences marked inline. This is compatible with -fno-elide-type.</p> - -Default: -<pre> -t.cc:4:5: <span class="note">note</span>: candidate function not viable: no known conversion from 'vector<map<[...], map<<span class="template-highlight">float</span>, [...]>>>' to 'vector<map<[...], map<<span class="template-highlight">double</span>, [...]>>>' for 1st argument; -</pre> --fdiagnostics-show-template-tree -<pre> -t.cc:4:5: <span class="note">note</span>: candidate function not viable: no known conversion for 1st argument; - vector< - map< - [...], - map< - [<span class="template-highlight">float</span> != <span class="template-highlight">float</span>], - [...]>>> -</pre> -</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: - -<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> -</dd> - -<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> -<dt id="opt_Wambiguous-member-template"><b>-Wambiguous-member-template</b>: -Warn about unqualified uses of a member template whose name resolves -to another template at the location of the use.</dt> -<dd>This option, which defaults to on, enables a warning in the -following code: - -<pre> -template<typename T> struct set{}; -template<typename T> struct trait { typedef const T& type; }; -struct Value { - template<typename T> void set(typename trait<T>::type value) {} -}; -void foo() { - Value v; - v.set<double>(3.2); -} -</pre> - -<p>C++ [basic.lookup.classref] requires this to be an error, but, -because it's hard to work around, Clang downgrades it to a warning as -an extension.</p> -</dd> - -<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> -<dt id="opt_Wbind-to-temporary-copy"><b>-Wbind-to-temporary-copy</b>: Warn about -an unusable copy constructor when binding a reference to a temporary.</dt> -<dd>This option, which defaults to on, enables warnings about binding a -reference to a temporary when the temporary doesn't have a usable copy -constructor. For example: - -<pre> - struct NonCopyable { - NonCopyable(); - private: - NonCopyable(const NonCopyable&); - }; - void foo(const NonCopyable&); - void bar() { - foo(NonCopyable()); // Disallowed in C++98; allowed in C++11. - } -</pre> -<pre> - struct NonCopyable2 { - NonCopyable2(); - NonCopyable2(NonCopyable2&); - }; - void foo(const NonCopyable2&); - void bar() { - foo(NonCopyable2()); // Disallowed in C++98; allowed in C++11. - } -</pre> - -<p>Note that if <tt>NonCopyable2::NonCopyable2()</tt> has a default -argument whose instantiation produces a compile error, that error will -still be a hard error in C++98 mode even if this warning is turned -off.</p> - -</dd> - -</dl> - -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> -<h3 id="cl_crash_diagnostics">Options to Control Clang Crash Diagnostics</h3> -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> - -<p>As unbelievable as it may sound, Clang does crash from time to time. -Generally, this only occurs to those living on the -<a href="http://llvm.org/releases/download.html#svn">bleeding edge</a>. Clang -goes to great lengths to assist you in filing a bug report. Specifically, Clang -generates preprocessed source file(s) and associated run script(s) upon a -crash. These files should be attached to a bug report to ease reproducibility -of the failure. Below are the command line options to control the crash -diagnostics. -</p> - -<p><b>-fno-crash-diagnostics</b>: Disable auto-generation of preprocessed -source files during a clang crash.</p> - -<p>The -fno-crash-diagnostics flag can be helpful for speeding the process of -generating a delta reduced test case.</p> - - -<!-- ======================================================================= --> -<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 id="diagnostics_display">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> - -<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>A <a href="#diagnostics_categories">high-level category</a> for the - diagnostic for clients that want to group diagnostics by class (for - diagnostics that support it) [<a - href="#opt_fdiagnostics-show-category">-fdiagnostics-show-category</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>For more information please see <a href="#cl_diag_formatting">Formatting of -Diagnostics</a>.</p> - - -<h4 id="diagnostics_mappings">Diagnostic Mappings</h4> - -<p>All diagnostics are mapped into one of these 5 classes:</p> - -<ul> -<li>Ignored</li> -<li>Note</li> -<li>Warning</li> -<li>Error</li> -<li>Fatal</li> -</ul> - -<h4 id="diagnostics_categories">Diagnostic Categories</h4> - -<p>Though not shown by default, diagnostics may each be associated with a - high-level category. This category is intended to make it possible to triage - builds that produce a large number of errors or warnings in a grouped way. -</p> - -<p>Categories are not shown by default, but they can be turned on with the -<a href="#opt_fdiagnostics-show-category">-fdiagnostics-show-category</a> option. -When set to "<tt>name</tt>", the category is printed textually in the diagnostic -output. When it is set to "<tt>id</tt>", a category number is printed. The -mapping of category names to category id's can be obtained by running '<tt>clang - --print-diagnostic-categories</tt>'. -</p> - -<h4 id="diagnostics_commandline">Controlling Diagnostics via Command Line - Flags</h4> - -<p>TODO: -W flags, -pedantic, etc</p> - -<h4 id="diagnostics_pragmas">Controlling Diagnostics via Pragmas</h4> - -<p>Clang can also control what diagnostics are enabled through the use of -pragmas in the source code. This is useful for turning off specific warnings -in a section of source code. Clang supports GCC's pragma for compatibility -with existing source code, as well as several extensions. </p> - -<p>The pragma may control any warning that can be used from the command line. -Warnings may be set to ignored, warning, error, or fatal. The following -example code will tell Clang or GCC to ignore the -Wall warnings:</p> - -<pre> -#pragma GCC diagnostic ignored "-Wall" -</pre> - -<p>In addition to all of the functionality provided by GCC's pragma, Clang -also allows you to push and pop the current warning state. This is particularly -useful when writing a header file that will be compiled by other people, because -you don't know what warning flags they build with.</p> - -<p>In the below example --Wmultichar is ignored for only a single line of code, after which the -diagnostics return to whatever state had previously existed.</p> - -<pre> -#pragma clang diagnostic push -#pragma clang diagnostic ignored "-Wmultichar" - -char b = 'df'; // no warning. - -#pragma clang diagnostic pop -</pre> - -<p>The push and pop pragmas will save and restore the full diagnostic state of -the compiler, regardless of how it was set. That means that it is possible to -use push and pop around GCC compatible diagnostics and Clang will push and pop -them appropriately, while GCC will ignore the pushes and pops as unknown -pragmas. It should be noted that while Clang supports the GCC pragma, Clang and -GCC do not support the exact same set of warnings, so even when using GCC -compatible #pragmas there is no guarantee that they will have identical behaviour -on both compilers. </p> - -<h4 id="diagnostics_systemheader">Controlling Diagnostics in System Headers</h4> - -<p>Warnings are suppressed when they occur in system headers. By default, an -included file is treated as a system header if it is found in an include path -specified by <tt>-isystem</tt>, but this can be overridden in several ways.</p> - -<p>The <tt>system_header</tt> pragma can be used to mark the current file as -being a system header. No warnings will be produced from the location of the -pragma onwards within the same file.</p> - -<pre> -char a = 'xy'; // warning - -#pragma clang system_header - -char b = 'ab'; // no warning -</pre> - -<p>The <tt>-isystem-prefix</tt> and <tt>-ino-system-prefix</tt> command-line -arguments can be used to override whether subsets of an include path are treated -as system headers. When the name in a <tt>#include</tt> directive is found -within a header search path and starts with a system prefix, the header is -treated as a system header. The last prefix on the command-line which matches -the specified header name takes precedence. For instance:</p> - -<pre> -clang -Ifoo -isystem bar -isystem-prefix x/ -ino-system-prefix x/y/ -</pre> - -<p>Here, <tt>#include "x/a.h"</tt> is treated as including a system header, even -if the header is found in <tt>foo</tt>, and <tt>#include "x/y/b.h"</tt> is -treated as not including a system header, even if the header is found in -<tt>bar</tt>. -</p> - -<p>A <tt>#include</tt> directive which finds a file relative to the current -directory is treated as including a system header if the including file is -treated as a system header.</p> - -<h4 id="diagnostics_enable_everything">Enabling All Warnings</h4> - -<p>In addition to the traditional <tt>-W</tt> flags, one can enable <b>all</b> - warnings by passing <tt>-Weverything</tt>. - This works as expected with <tt>-Werror</tt>, - and also includes the warnings from <tt>-pedantic</tt>.</p> - -<p>Note that when combined with <tt>-w</tt> (which disables all warnings), that - flag wins.</p> - -<h4 id="analyzer_diagnositics">Controlling Static Analyzer Diagnostics</h4> - -<p>While not strictly part of the compiler, the diagnostics from Clang's <a -href="http://clang-analyzer.llvm.org">static analyzer</a> can also be influenced -by the user via changes to the source code. See the available -<a href = "http://clang-analyzer.llvm.org/annotations.html" >annotations</a> and -the analyzer's -<a href= "http://clang-analyzer.llvm.org/faq.html#exclude_code" >FAQ page</a> for -more information. - -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> -<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 -highly effective at speeding up program compilation on systems with very large -system headers (e.g., Mac OS/X).</p> - -<h4>Generating a PCH File</h4> - -<p>To generate a PCH 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.pch -</pre> - -<h4>Using a PCH File</h4> - -<p>A PCH 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 PCH 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 PCH 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 PCH files -for headers that are directly included within a source file. For example:</p> - -<pre> - $ clang -x c-header test.h -o test.h.pch - $ cat test.c - #include "test.h" - $ clang test.c -o test -</pre> - -<p>In this example, <tt>clang</tt> will not automatically use the PCH 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> - -<h4>Relocatable PCH Files</h4> -<p>It is sometimes necessary to build a precompiled header from headers that -are not yet in their final, installed locations. For example, one might build a -precompiled header within the build tree that is then meant to be installed -alongside the headers. Clang permits the creation of "relocatable" precompiled -headers, which are built with a given path (into the build directory) and can -later be used from an installed location.</p> - -<p>To build a relocatable precompiled header, place your headers into a -subdirectory whose structure mimics the installed location. For example, if you -want to build a precompiled header for the header <code>mylib.h</code> that -will be installed into <code>/usr/include</code>, create a subdirectory -<code>build/usr/include</code> and place the header <code>mylib.h</code> into -that subdirectory. If <code>mylib.h</code> depends on other headers, then -they can be stored within <code>build/usr/include</code> in a way that mimics -the installed location.</p> - -<p>Building a relocatable precompiled header requires two additional arguments. -First, pass the <code>--relocatable-pch</code> flag to indicate that the -resulting PCH file should be relocatable. Second, pass -<code>-isysroot /path/to/build</code>, which makes all includes for your -library relative to the build directory. For example:</p> - -<pre> - # clang -x c-header --relocatable-pch -isysroot /path/to/build /path/to/build/mylib.h mylib.h.pch -</pre> - -<p>When loading the relocatable PCH file, the various headers used in the PCH -file are found from the system header root. For example, <code>mylib.h</code> -can be found in <code>/usr/include/mylib.h</code>. If the headers are installed -in some other system root, the <code>-isysroot</code> option can be used provide -a different system root from which the headers will be based. For example, -<code>-isysroot /Developer/SDKs/MacOSX10.4u.sdk</code> will look for -<code>mylib.h</code> in -<code>/Developer/SDKs/MacOSX10.4u.sdk/usr/include/mylib.h</code>.</p> - -<p>Relocatable precompiled headers are intended to be used in a limited number -of cases where the compilation environment is tightly controlled and the -precompiled header cannot be generated after headers have been installed. -Relocatable precompiled headers also have some performance impact, because -the difference in location between the header locations at PCH build time vs. -at the time of PCH use requires one of the PCH optimizations, -<code>stat()</code> caching, to be disabled. However, this change is only -likely to affect PCH files that reference a large number of headers.</p> - -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> -<h3 id="codegen">Controlling Code Generation</h3> -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> - -<p>Clang provides a number of ways to control code generation. The options are listed below.</p> - -<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> -<dl> -<dt id="opt_fsanitize"><b>-fsanitize=check1,check2</b>: Turn on runtime checks -for various forms of undefined behavior.</dt> - -<dd>This option controls whether Clang adds runtime checks for various forms of -undefined behavior, and is disabled by default. If a check fails, a diagnostic -message is produced at runtime explaining the problem. The main checks are: - -<ul> -<li id="opt_fsanitize_address"><tt>-fsanitize=address</tt>: - <a href="AddressSanitizer.html">AddressSanitizer</a>, a memory error - detector.</li> -<li id="opt_fsanitize_thread"><tt>-fsanitize=thread</tt>: - <a href="ThreadSanitizer.html">ThreadSanitizer</a>, an <em>experimental</em> - data race detector. Not ready for widespread use.</li> -<li id="opt_fsanitize_undefined"><tt>-fsanitize=undefined</tt>: - Enables all the checks listed below.</li> -</ul> - -The following more fine-grained checks are also available: - -<ul> -<li id="opt_fsanitize_alignment"><tt>-fsanitize=alignment</tt>: - Use of a misaligned pointer or creation of a misaligned reference.</li> -<li id="opt_fsanitize_divide-by-zero"><tt>-fsanitize=divide-by-zero</tt>: - Division by zero.</li> -<li id="opt_fsanitize_float-cast-overflow"><tt>-fsanitize=float-cast-overflow</tt>: - Conversion to, from, or between floating-point types which would overflow - the destination.</li> -<li id="opt_fsanitize_null"><tt>-fsanitize=null</tt>: - Use of a null pointer or creation of a null reference.</li> -<li id="opt_fsanitize_object-size"><tt>-fsanitize=object-size</tt>: - An attempt to use bytes which the optimizer can determine are not part of - the object being accessed. - The sizes of objects are determined using <tt>__builtin_object_size</tt>, and - consequently may be able to detect more problems at higher optimization - levels.</li> -<li id="opt_fsanitize_return"><tt>-fsanitize=return</tt>: - In C++, reaching the end of a value-returning function without returning a - value.</li> -<li id="opt_fsanitize_shift"><tt>-fsanitize=shift</tt>: - Shift operators where the amount shifted is greater or equal to the - promoted bit-width of the left hand side or less than zero, or where - the left hand side is negative. For a signed left shift, also checks - for signed overflow in C, and for unsigned overflow in C++.</li> -<li id="opt_fsanitize_signed-integer-overflow"><tt>-fsanitize=signed-integer-overflow</tt>: - Signed integer overflow, including all the checks added by <tt>-ftrapv</tt>, - and checking for overflow in signed division (<tt>INT_MIN / -1</tt>).</li> -<li id="opt_fsanitize_unreachable"><tt>-fsanitize=unreachable</tt>: - If control flow reaches __builtin_unreachable.</li> -<li id="opt_fsanitize_vla-bound"><tt>-fsanitize=vla-bound</tt>: - A variable-length array whose bound does not evaluate to a positive value.</li> -<li id="opt_fsanitize_vptr"><tt>-fsanitize=vptr</tt>: - Use of an object whose vptr indicates that it is of the wrong dynamic type, - or that its lifetime has not begun or has ended. Incompatible with - <tt>-fno-rtti</tt>.</li> -</ul> - -The <tt>-fsanitize=</tt> argument must also be provided when linking, in order -to link to the appropriate runtime library. It is not possible to combine the -<tt>-fsanitize=address</tt> and <tt>-fsanitize=thread</tt> checkers in the same -program. -</dd> - -<dt id="opt_faddress-sanitizer"><b>-f[no-]address-sanitizer</b>: -Deprecated synonym for <a href="#opt_fsanitize_address"><tt>-f[no-]sanitize=address</tt></a>. - -<dt id="opt_fthread-sanitizer"><b>-f[no-]thread-sanitizer</b>: -Deprecated synonym for <a href="#opt_fsanitize_address"><tt>-f[no-]sanitize=thread</tt></a>. - -<dt id="opt_fcatch-undefined-behavior"><b>-fcatch-undefined-behavior</b>: -Deprecated synonym for <a href="#opt_fsanitize_undefined"><tt>-fsanitize=undefined</tt></a>. - -<dt id="opt_fno-assume-sane-operator-new"><b>-fno-assume-sane-operator-new</b>: -Don't assume that the C++'s new operator is sane.</dt> -<dd>This option tells the compiler to do not assume that C++'s global new -operator will always return a pointer that does not -alias any other pointer when the function returns.</dd> - -<dt id="opt_ftrap-function"><b>-ftrap-function=[name]</b>: Instruct code -generator to emit a function call to the specified function name for -<tt>__builtin_trap()</tt>.</dt> - -<dd>LLVM code generator translates <tt>__builtin_trap()</tt> to a trap -instruction if it is supported by the target ISA. Otherwise, the builtin is -translated into a call to <tt>abort</tt>. If this option is set, then the code -generator will always lower the builtin to a call to the specified function -regardless of whether the target ISA has a trap instruction. This option is -useful for environments (e.g. deeply embedded) where a trap cannot be properly -handled, or when some custom behavior is desired.</dd> - -<dt id="opt_ftls-model"><b>-ftls-model=[model]</b>: Select which TLS model to -use.</dt> -<dd>Valid values are: <tt>global-dynamic</tt>, <tt>local-dynamic</tt>, -<tt>initial-exec</tt> and <tt>local-exec</tt>. The default value is -<tt>global-dynamic</tt>. The compiler may use a different model if the selected -model is not supported by the target, or if a more efficient model can be used. -The TLS model can be overridden per variable using the <tt>tls_model</tt> -attribute. -</dd> -</dl> - -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> -<h3 id="debuginfosize">Controlling Size of Debug Information</h3> -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> - -<p>Debug info kind generated by Clang can be set by one of the flags listed -below. If multiple flags are present, the last one is used.</p> - -<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --> -<dl> -<dt id="opt_g0"><b>-g0</b>: Don't generate any debug info (default). - -<dt id="opt_gline-tables-only"><b>-gline-tables-only</b>: -Generate line number tables only. -<dd> -This kind of debug info allows to obtain stack traces with function -names, file names and line numbers (by such tools as -gdb or addr2line). It doesn't contain any other data (e.g. -description of local variables or function parameters). -</dd> - -<dt id="opt_g"><b>-g</b>: Generate complete debug info. -</dl> - -<!-- ======================================================================= --> -<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>Arrays that are VLA's according to the standard, but which can be constant - folded by the frontend are treated as fixed size arrays. This occurs for - things like "int X[(1, 2)];", which is technically a VLA. c* modes are - strictly compliant and treat these as VLAs.</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 #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 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. In C++11 -it can be emulated by assigning lambda functions to local variables, e.g: -<pre> - auto const local_function = [&](int parameter) { - // Do something - }; - ... - local_function(1); -</pre> -</li> - -<li>clang does not support global register variables; this is unlikely -to be implemented soon because it requires additional LLVM backend support. -</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> - -<li>clang does not support __builtin_va_arg_pack/__builtin_va_arg_pack_len. -This is used rarely, but in some potentially interesting places, like the -glibc headers, so it may be implemented pending user demand. Note that -because clang pretends to be like GCC 4.2, and this extension was introduced -in 4.3, the glibc headers will not try to use this extension with clang at -the moment.</li> - -<li>clang does not support the gcc extension for forward-declaring function -parameters; this has not shown up in any real-world code yet, though, so it -might never be implemented.</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> -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> - -<ul> - -<li>clang does not support the gcc extension that allows variable-length arrays -in structures. This is for a few reasons: one, it is tricky -to implement, two, the extension is completely undocumented, and three, the -extension appears to be rarely used. Note that clang <em>does</em> support -flexible array members (arrays with a zero or unspecified size at the end of -a structure).</li> - -<li>clang does not have an equivalent to gcc's "fold"; this means that -clang doesn't accept some constructs gcc might accept in contexts where a -constant expression is required, like "x-x" where x is a variable.</li> - -<li>clang does not support __builtin_apply and friends; this extension is -extremely obscure and difficult to implement reliably.</li> - -</ul> - -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> -<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. This is the default for Windows targets. Note that the -support is incomplete; enabling Microsoft extensions will silently drop -certain constructs (including __declspec and Microsoft-style asm statements). -</p> - -<p>clang has a -fms-compatibility flag that makes clang accept enough -invalid C++ to be able to parse most Microsoft headers. This flag is enabled by -default for Windows targets.</p> - -<p>-fdelayed-template-parsing lets clang delay all template instantiation until -the end of a translation unit. This flag is enabled by default for Windows -targets.</p> - -<ul> -<li>clang allows setting _MSC_VER with -fmsc-version=. It defaults to 1300 which -is the same as Visual C/C++ 2003. Any number is supported and can greatly affect -what Windows SDK and c++stdlib headers clang can compile. This option will be -removed when clang supports the full set of MS extensions required for these -headers.</li> - -<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> - -<li>clang defaults to C++11 for Windows targets.</li> -</ul> - -<!-- ======================================================================= --> -<h2 id="cxx">C++ Language Features</h2> -<!-- ======================================================================= --> - -<p>clang fully implements all of standard C++98 except for exported templates -(which were removed in C++11), and -<a href="http://clang.llvm.org/cxx_status.html">many C++11 features</a> are also -implemented.</p> - -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> -<h3 id="cxx_implimits">Controlling implementation limits</h3> -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> - -<p><b>-fconstexpr-depth=N</b>: Sets the limit for recursive constexpr function -invocations to N. The default is 512.</p> - -<p><b>-ftemplate-depth=N</b>: Sets the limit for recursively nested template -instantiations to N. The default is 1024.</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> -<!-- ======================== --> - -<p>The support for X86 (both 32-bit and 64-bit) is considered stable on Darwin -(Mac OS/X), Linux, FreeBSD, and Dragonfly BSD: it has been tested to correctly -compile many large C, C++, Objective-C, and Objective-C++ codebases.</p> - -<p>On x86_64-mingw32, passing i128(by value) is incompatible to Microsoft x64 -calling conversion. You might need to tweak WinX86_64ABIInfo::classify() -in lib/CodeGen/TargetInfo.cpp.</p> - -<!-- ======================== --> -<h4 id="target_arch_arm">ARM</h4> -<!-- ======================== --> - -<p>The support for ARM (specifically ARMv6 and ARMv7) is considered stable on -Darwin (iOS): it has been tested to correctly compile many large C, C++, -Objective-C, and Objective-C++ codebases. Clang only supports a limited number -of ARM architectures. It does not yet fully support ARMv5, for example.</p> - -<!-- ======================== --> -<h4 id="target_arch_other">Other platforms</h4> -<!-- ======================== --> -clang currently contains some support for PPC and Sparc; however, significant -pieces of code generation are still missing, and they haven't undergone -significant testing. - -<p>clang contains limited support for the MSP430 embedded processor, but both -the clang support and the LLVM backend support are highly experimental. - -<p>Other platforms are completely unsupported at the moment. Adding the -minimal support needed for parsing and semantic analysis on a new platform -is quite easy; see lib/Basic/Targets.cpp in the clang source tree. This level -of support is also sufficient for conversion to LLVM IR for simple programs. -Proper support for conversion to LLVM IR requires adding code to -lib/CodeGen/CGCall.cpp at the moment; this is likely to change soon, though. -Generating assembly requires a suitable LLVM backend. - -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> -<h3 id="target_os">Operating System Features and Limitations</h3> -<!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = --> - -<!-- ======================================= --> -<h4 id="target_os_darwin">Darwin (Mac OS/X)</h4> -<!-- ======================================= --> - -<p>None</p> - -<!-- ======================================= --> -<h4 id="target_os_win32">Windows</h4> -<!-- ======================================= --> - -<p>Experimental supports are on Cygming.</p> - -<p>See also <a href="#c_ms">Microsoft Extensions</a>.</p> - -<h5>Cygwin</h5> - -<p>Clang works on Cygwin-1.7.</p> - -<h5>MinGW32</h5> - -<p>Clang works on some mingw32 distributions. -Clang assumes directories as below;</p> - -<ul> -<li><tt>C:/mingw/include</tt></li> -<li><tt>C:/mingw/lib</tt></li> -<li><tt>C:/mingw/lib/gcc/mingw32/4.[3-5].0/include/c++</tt></li> -</ul> - -<p>On MSYS, a few tests might fail.</p> - -<h5>MinGW-w64</h5> - -<p>For 32-bit (i686-w64-mingw32), and 64-bit (x86_64-w64-mingw32), Clang assumes as below;<p> - -<ul> -<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> -<li><tt>some_directory/bin/gcc.exe</tt></li> -<li><tt>some_directory/bin/clang.exe</tt></li> -<li><tt>some_directory/bin/clang++.exe</tt></li> -<li><tt>some_directory/bin/../include/c++/GCC_version</tt></li> -<li><tt>some_directory/bin/../include/c++/GCC_version/x86_64-w64-mingw32</tt></li> -<li><tt>some_directory/bin/../include/c++/GCC_version/i686-w64-mingw32</tt></li> -<li><tt>some_directory/bin/../include/c++/GCC_version/backward</tt></li> -<li><tt>some_directory/bin/../x86_64-w64-mingw32/include</tt></li> -<li><tt>some_directory/bin/../i686-w64-mingw32/include</tt></li> -<li><tt>some_directory/bin/../include</tt></li> -</ul> - -<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>. - -<p>Clang expects the GCC executable "gcc.exe" compiled for i686-w64-mingw32 (or x86_64-w64-mingw32) to be present on PATH.</p> - -<p><a href="http://llvm.org/bugs/show_bug.cgi?id=9072">Some tests might fail</a> -on x86_64-w64-mingw32.</p> - -</div> -</body> -</html> |
