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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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diff --git a/share/doc/gcc/Preprocessor-Options.html b/share/doc/gcc/Preprocessor-Options.html new file mode 100644 index 0000000..77c357a --- /dev/null +++ b/share/doc/gcc/Preprocessor-Options.html @@ -0,0 +1,733 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- This file documents the use of the GNU compilers. + +Copyright (C) 1988-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Using the GNU Compiler Collection (GCC): Preprocessor Options</title> + +<meta name="description" content="Using the GNU Compiler Collection (GCC): Preprocessor Options"> +<meta name="keywords" content="Using the GNU Compiler Collection (GCC): Preprocessor Options"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Indices.html#Indices" rel="index" title="Indices"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Invoking-GCC.html#Invoking-GCC" rel="up" title="Invoking GCC"> +<link href="Assembler-Options.html#Assembler-Options" rel="next" title="Assembler Options"> +<link href="Instrumentation-Options.html#Instrumentation-Options" rel="previous" title="Instrumentation Options"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en_US" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="Preprocessor-Options"></a> +<div class="header"> +<p> +Next: <a href="Assembler-Options.html#Assembler-Options" accesskey="n" rel="next">Assembler Options</a>, Previous: <a href="Instrumentation-Options.html#Instrumentation-Options" accesskey="p" rel="previous">Instrumentation Options</a>, Up: <a href="Invoking-GCC.html#Invoking-GCC" accesskey="u" rel="up">Invoking GCC</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Options-Controlling-the-Preprocessor"></a> +<h3 class="section">3.13 Options Controlling the Preprocessor</h3> +<a name="index-preprocessor-options"></a> +<a name="index-options_002c-preprocessor"></a> + +<p>These options control the C preprocessor, which is run on each C source +file before actual compilation. +</p> +<p>If you use the <samp>-E</samp> option, nothing is done except preprocessing. +Some of these options make sense only together with <samp>-E</samp> because +they cause the preprocessor output to be unsuitable for actual +compilation. +</p> +<p>In addition to the options listed here, there are a number of options +to control search paths for include files documented in +<a href="Directory-Options.html#Directory-Options">Directory Options</a>. +Options to control preprocessor diagnostics are listed in +<a href="Warning-Options.html#Warning-Options">Warning Options</a>. +</p> +<dl compact="compact"> +<dd> + + +<a name="index-D-1"></a> +</dd> +<dt><code>-D <var>name</var></code></dt> +<dd><p>Predefine <var>name</var> as a macro, with definition <code>1</code>. +</p> +</dd> +<dt><code>-D <var>name</var>=<var>definition</var></code></dt> +<dd><p>The contents of <var>definition</var> are tokenized and processed as if +they appeared during translation phase three in a ‘<samp>#define</samp>’ +directive. In particular, the definition is truncated by +embedded newline characters. +</p> +<p>If you are invoking the preprocessor from a shell or shell-like +program you may need to use the shell’s quoting syntax to protect +characters such as spaces that have a meaning in the shell syntax. +</p> +<p>If you wish to define a function-like macro on the command line, write +its argument list with surrounding parentheses before the equals sign +(if any). Parentheses are meaningful to most shells, so you should +quote the option. With <code>sh</code> and <code>csh</code>, +<samp>-D'<var>name</var>(<var>args…</var>)=<var>definition</var>'</samp> works. +</p> +<p><samp>-D</samp> and <samp>-U</samp> options are processed in the order they +are given on the command line. All <samp>-imacros <var>file</var></samp> and +<samp>-include <var>file</var></samp> options are processed after all +<samp>-D</samp> and <samp>-U</samp> options. +</p> +<a name="index-U"></a> +</dd> +<dt><code>-U <var>name</var></code></dt> +<dd><p>Cancel any previous definition of <var>name</var>, either built in or +provided with a <samp>-D</samp> option. +</p> +<a name="index-include"></a> +</dd> +<dt><code>-include <var>file</var></code></dt> +<dd><p>Process <var>file</var> as if <code>#include "file"</code> appeared as the first +line of the primary source file. However, the first directory searched +for <var>file</var> is the preprocessor’s working directory <em>instead of</em> +the directory containing the main source file. If not found there, it +is searched for in the remainder of the <code>#include "…"</code> search +chain as normal. +</p> +<p>If multiple <samp>-include</samp> options are given, the files are included +in the order they appear on the command line. +</p> +<a name="index-imacros"></a> +</dd> +<dt><code>-imacros <var>file</var></code></dt> +<dd><p>Exactly like <samp>-include</samp>, except that any output produced by +scanning <var>file</var> is thrown away. Macros it defines remain defined. +This allows you to acquire all the macros from a header without also +processing its declarations. +</p> +<p>All files specified by <samp>-imacros</samp> are processed before all files +specified by <samp>-include</samp>. +</p> +<a name="index-undef"></a> +</dd> +<dt><code>-undef</code></dt> +<dd><p>Do not predefine any system-specific or GCC-specific macros. The +standard predefined macros remain defined. +</p> +<a name="index-pthread"></a> +</dd> +<dt><code>-pthread</code></dt> +<dd><p>Define additional macros required for using the POSIX threads library. +You should use this option consistently for both compilation and linking. +This option is supported on GNU/Linux targets, most other Unix derivatives, +and also on x86 Cygwin and MinGW targets. +</p> +<a name="index-M"></a> +<a name="index-make"></a> +<a name="index-dependencies_002c-make"></a> +</dd> +<dt><code>-M</code></dt> +<dd><p>Instead of outputting the result of preprocessing, output a rule +suitable for <code>make</code> describing the dependencies of the main +source file. The preprocessor outputs one <code>make</code> rule containing +the object file name for that source file, a colon, and the names of all +the included files, including those coming from <samp>-include</samp> or +<samp>-imacros</samp> command-line options. +</p> +<p>Unless specified explicitly (with <samp>-MT</samp> or <samp>-MQ</samp>), the +object file name consists of the name of the source file with any +suffix replaced with object file suffix and with any leading directory +parts removed. If there are many included files then the rule is +split into several lines using ‘<samp>\</samp>’-newline. The rule has no +commands. +</p> +<p>This option does not suppress the preprocessor’s debug output, such as +<samp>-dM</samp>. To avoid mixing such debug output with the dependency +rules you should explicitly specify the dependency output file with +<samp>-MF</samp>, or use an environment variable like +<code>DEPENDENCIES_OUTPUT</code> (see <a href="Environment-Variables.html#Environment-Variables">Environment Variables</a>). Debug output +is still sent to the regular output stream as normal. +</p> +<p>Passing <samp>-M</samp> to the driver implies <samp>-E</samp>, and suppresses +warnings with an implicit <samp>-w</samp>. +</p> +<a name="index-MM"></a> +</dd> +<dt><code>-MM</code></dt> +<dd><p>Like <samp>-M</samp> but do not mention header files that are found in +system header directories, nor header files that are included, +directly or indirectly, from such a header. +</p> +<p>This implies that the choice of angle brackets or double quotes in an +‘<samp>#include</samp>’ directive does not in itself determine whether that +header appears in <samp>-MM</samp> dependency output. +</p> +<a name="dashMF"></a><a name="index-MF"></a> +</dd> +<dt><code>-MF <var>file</var></code></dt> +<dd><p>When used with <samp>-M</samp> or <samp>-MM</samp>, specifies a +file to write the dependencies to. If no <samp>-MF</samp> switch is given +the preprocessor sends the rules to the same place it would send +preprocessed output. +</p> +<p>When used with the driver options <samp>-MD</samp> or <samp>-MMD</samp>, +<samp>-MF</samp> overrides the default dependency output file. +</p> +<p>If <var>file</var> is <samp>-</samp>, then the dependencies are written to <samp>stdout</samp>. +</p> +<a name="index-MG"></a> +</dd> +<dt><code>-MG</code></dt> +<dd><p>In conjunction with an option such as <samp>-M</samp> requesting +dependency generation, <samp>-MG</samp> assumes missing header files are +generated files and adds them to the dependency list without raising +an error. The dependency filename is taken directly from the +<code>#include</code> directive without prepending any path. <samp>-MG</samp> +also suppresses preprocessed output, as a missing header file renders +this useless. +</p> +<p>This feature is used in automatic updating of makefiles. +</p> +<a name="index-Mno_002dmodules"></a> +</dd> +<dt><code>-Mno-modules</code></dt> +<dd><p>Disable dependency generation for compiled module interfaces. +</p> +<a name="index-MP"></a> +</dd> +<dt><code>-MP</code></dt> +<dd><p>This option instructs CPP to add a phony target for each dependency +other than the main file, causing each to depend on nothing. These +dummy rules work around errors <code>make</code> gives if you remove header +files without updating the <samp>Makefile</samp> to match. +</p> +<p>This is typical output: +</p> +<div class="smallexample"> +<pre class="smallexample">test.o: test.c test.h + +test.h: +</pre></div> + +<a name="index-MT"></a> +</dd> +<dt><code>-MT <var>target</var></code></dt> +<dd> +<p>Change the target of the rule emitted by dependency generation. By +default CPP takes the name of the main input file, deletes any +directory components and any file suffix such as ‘<samp>.c</samp>’, and +appends the platform’s usual object suffix. The result is the target. +</p> +<p>An <samp>-MT</samp> option sets the target to be exactly the string you +specify. If you want multiple targets, you can specify them as a single +argument to <samp>-MT</samp>, or use multiple <samp>-MT</samp> options. +</p> +<p>For example, <samp><span class="nolinebreak">-MT</span> '$(objpfx)foo.o'<!-- /@w --></samp> might give +</p> +<div class="smallexample"> +<pre class="smallexample">$(objpfx)foo.o: foo.c +</pre></div> + +<a name="index-MQ"></a> +</dd> +<dt><code>-MQ <var>target</var></code></dt> +<dd> +<p>Same as <samp>-MT</samp>, but it quotes any characters which are special to +Make. <samp><span class="nolinebreak">-MQ</span> '$(objpfx)foo.o'<!-- /@w --></samp> gives +</p> +<div class="smallexample"> +<pre class="smallexample">$$(objpfx)foo.o: foo.c +</pre></div> + +<p>The default target is automatically quoted, as if it were given with +<samp>-MQ</samp>. +</p> +<a name="index-MD"></a> +</dd> +<dt><code>-MD</code></dt> +<dd><p><samp>-MD</samp> is equivalent to <samp>-M -MF <var>file</var></samp>, except that +<samp>-E</samp> is not implied. The driver determines <var>file</var> based on +whether an <samp>-o</samp> option is given. If it is, the driver uses its +argument but with a suffix of <samp>.d</samp>, otherwise it takes the name +of the input file, removes any directory components and suffix, and +applies a <samp>.d</samp> suffix. +</p> +<p>If <samp>-MD</samp> is used in conjunction with <samp>-E</samp>, any +<samp>-o</samp> switch is understood to specify the dependency output file +(see <a href="#dashMF">-MF</a>), but if used without <samp>-E</samp>, each <samp>-o</samp> +is understood to specify a target object file. +</p> +<p>Since <samp>-E</samp> is not implied, <samp>-MD</samp> can be used to generate +a dependency output file as a side effect of the compilation process. +</p> +<a name="index-MMD"></a> +</dd> +<dt><code>-MMD</code></dt> +<dd><p>Like <samp>-MD</samp> except mention only user header files, not system +header files. +</p> +<a name="index-fpreprocessed"></a> +</dd> +<dt><code>-fpreprocessed</code></dt> +<dd><p>Indicate to the preprocessor that the input file has already been +preprocessed. This suppresses things like macro expansion, trigraph +conversion, escaped newline splicing, and processing of most directives. +The preprocessor still recognizes and removes comments, so that you can +pass a file preprocessed with <samp>-C</samp> to the compiler without +problems. In this mode the integrated preprocessor is little more than +a tokenizer for the front ends. +</p> +<p><samp>-fpreprocessed</samp> is implicit if the input file has one of the +extensions ‘<samp>.i</samp>’, ‘<samp>.ii</samp>’ or ‘<samp>.mi</samp>’. These are the +extensions that GCC uses for preprocessed files created by +<samp>-save-temps</samp>. +</p> +<a name="index-fdirectives_002donly"></a> +</dd> +<dt><code>-fdirectives-only</code></dt> +<dd><p>When preprocessing, handle directives, but do not expand macros. +</p> +<p>The option’s behavior depends on the <samp>-E</samp> and <samp>-fpreprocessed</samp> +options. +</p> +<p>With <samp>-E</samp>, preprocessing is limited to the handling of directives +such as <code>#define</code>, <code>#ifdef</code>, and <code>#error</code>. Other +preprocessor operations, such as macro expansion and trigraph +conversion are not performed. In addition, the <samp>-dD</samp> option is +implicitly enabled. +</p> +<p>With <samp>-fpreprocessed</samp>, predefinition of command line and most +builtin macros is disabled. Macros such as <code>__LINE__</code>, which are +contextually dependent, are handled normally. This enables compilation of +files previously preprocessed with <code>-E -fdirectives-only</code>. +</p> +<p>With both <samp>-E</samp> and <samp>-fpreprocessed</samp>, the rules for +<samp>-fpreprocessed</samp> take precedence. This enables full preprocessing of +files previously preprocessed with <code>-E -fdirectives-only</code>. +</p> +<a name="index-fdollars_002din_002didentifiers"></a> +</dd> +<dt><code>-fdollars-in-identifiers</code></dt> +<dd><a name="fdollars_002din_002didentifiers"></a><p>Accept ‘<samp>$</samp>’ in identifiers. +</p> +<a name="index-fextended_002didentifiers"></a> +</dd> +<dt><code>-fextended-identifiers</code></dt> +<dd><p>Accept universal character names and extended characters in +identifiers. This option is enabled by default for C99 (and later C +standard versions) and C++. +</p> +<a name="index-fno_002dcanonical_002dsystem_002dheaders"></a> +</dd> +<dt><code>-fno-canonical-system-headers</code></dt> +<dd><p>When preprocessing, do not shorten system header paths with canonicalization. +</p> +<a name="index-fmax_002dinclude_002ddepth"></a> +</dd> +<dt><code>-fmax-include-depth=<var>depth</var></code></dt> +<dd><p>Set the maximum depth of the nested #include. The default is 200. +</p> +<a name="index-ftabstop"></a> +</dd> +<dt><code>-ftabstop=<var>width</var></code></dt> +<dd><p>Set the distance between tab stops. This helps the preprocessor report +correct column numbers in warnings or errors, even if tabs appear on the +line. If the value is less than 1 or greater than 100, the option is +ignored. The default is 8. +</p> +<a name="index-ftrack_002dmacro_002dexpansion"></a> +</dd> +<dt><code>-ftrack-macro-expansion<span class="roman">[</span>=<var>level</var><span class="roman">]</span></code></dt> +<dd><p>Track locations of tokens across macro expansions. This allows the +compiler to emit diagnostic about the current macro expansion stack +when a compilation error occurs in a macro expansion. Using this +option makes the preprocessor and the compiler consume more +memory. The <var>level</var> parameter can be used to choose the level of +precision of token location tracking thus decreasing the memory +consumption if necessary. Value ‘<samp>0</samp>’ of <var>level</var> de-activates +this option. Value ‘<samp>1</samp>’ tracks tokens locations in a +degraded mode for the sake of minimal memory overhead. In this mode +all tokens resulting from the expansion of an argument of a +function-like macro have the same location. Value ‘<samp>2</samp>’ tracks +tokens locations completely. This value is the most memory hungry. +When this option is given no argument, the default parameter value is +‘<samp>2</samp>’. +</p> +<p>Note that <code>-ftrack-macro-expansion=2</code> is activated by default. +</p> +<a name="index-fmacro_002dprefix_002dmap"></a> +</dd> +<dt><code>-fmacro-prefix-map=<var>old</var>=<var>new</var></code></dt> +<dd><p>When preprocessing files residing in directory <samp><var>old</var></samp>, +expand the <code>__FILE__</code> and <code>__BASE_FILE__</code> macros as if the +files resided in directory <samp><var>new</var></samp> instead. This can be used +to change an absolute path to a relative path by using <samp>.</samp> for +<var>new</var> which can result in more reproducible builds that are +location independent. This option also affects +<code>__builtin_FILE()</code> during compilation. See also +<samp>-ffile-prefix-map</samp> and <samp>-fcanon-prefix-map</samp>. +</p> +<a name="index-fexec_002dcharset"></a> +<a name="index-character-set_002c-execution"></a> +</dd> +<dt><code>-fexec-charset=<var>charset</var></code></dt> +<dd><p>Set the execution character set, used for string and character +constants. The default is UTF-8. <var>charset</var> can be any encoding +supported by the system’s <code>iconv</code> library routine. +</p> +<a name="index-fwide_002dexec_002dcharset"></a> +<a name="index-character-set_002c-wide-execution"></a> +</dd> +<dt><code>-fwide-exec-charset=<var>charset</var></code></dt> +<dd><p>Set the wide execution character set, used for wide string and +character constants. The default is one of UTF-32BE, UTF-32LE, UTF-16BE, +or UTF-16LE, whichever corresponds to the width of <code>wchar_t</code> and the +big-endian or little-endian byte order being used for code generation. As +with <samp>-fexec-charset</samp>, <var>charset</var> can be any encoding supported +by the system’s <code>iconv</code> library routine; however, you will have +problems with encodings that do not fit exactly in <code>wchar_t</code>. +</p> +<a name="index-finput_002dcharset"></a> +<a name="index-character-set_002c-input"></a> +</dd> +<dt><code>-finput-charset=<var>charset</var></code></dt> +<dd><p>Set the input character set, used for translation from the character +set of the input file to the source character set used by GCC. If the +locale does not specify, or GCC cannot get this information from the +locale, the default is UTF-8. This can be overridden by either the locale +or this command-line option. Currently the command-line option takes +precedence if there’s a conflict. <var>charset</var> can be any encoding +supported by the system’s <code>iconv</code> library routine. +</p> +<a name="index-fpch_002ddeps"></a> +</dd> +<dt><code>-fpch-deps</code></dt> +<dd><p>When using precompiled headers (see <a href="Precompiled-Headers.html#Precompiled-Headers">Precompiled Headers</a>), this flag +causes the dependency-output flags to also list the files from the +precompiled header’s dependencies. If not specified, only the +precompiled header are listed and not the files that were used to +create it, because those files are not consulted when a precompiled +header is used. +</p> +<a name="index-fpch_002dpreprocess"></a> +</dd> +<dt><code>-fpch-preprocess</code></dt> +<dd><p>This option allows use of a precompiled header (see <a href="Precompiled-Headers.html#Precompiled-Headers">Precompiled Headers</a>) together with <samp>-E</samp>. It inserts a special <code>#pragma</code>, +<code>#pragma GCC pch_preprocess "<var>filename</var>"</code> in the output to mark +the place where the precompiled header was found, and its <var>filename</var>. +When <samp>-fpreprocessed</samp> is in use, GCC recognizes this <code>#pragma</code> +and loads the PCH. +</p> +<p>This option is off by default, because the resulting preprocessed output +is only really suitable as input to GCC. It is switched on by +<samp>-save-temps</samp>. +</p> +<p>You should not write this <code>#pragma</code> in your own code, but it is +safe to edit the filename if the PCH file is available in a different +location. The filename may be absolute or it may be relative to GCC’s +current directory. +</p> +<a name="index-fworking_002ddirectory"></a> +<a name="index-fno_002dworking_002ddirectory"></a> +</dd> +<dt><code>-fworking-directory</code></dt> +<dd><p>Enable generation of linemarkers in the preprocessor output that +let the compiler know the current working directory at the time of +preprocessing. When this option is enabled, the preprocessor +emits, after the initial linemarker, a second linemarker with the +current working directory followed by two slashes. GCC uses this +directory, when it’s present in the preprocessed input, as the +directory emitted as the current working directory in some debugging +information formats. This option is implicitly enabled if debugging +information is enabled, but this can be inhibited with the negated +form <samp>-fno-working-directory</samp>. If the <samp>-P</samp> flag is +present in the command line, this option has no effect, since no +<code>#line</code> directives are emitted whatsoever. +</p> +<a name="index-A"></a> +</dd> +<dt><code>-A <var>predicate</var>=<var>answer</var></code></dt> +<dd><p>Make an assertion with the predicate <var>predicate</var> and answer +<var>answer</var>. This form is preferred to the older form <samp>-A +<var>predicate</var>(<var>answer</var>)</samp>, which is still supported, because +it does not use shell special characters. +</p> +</dd> +<dt><code>-A -<var>predicate</var>=<var>answer</var></code></dt> +<dd><p>Cancel an assertion with the predicate <var>predicate</var> and answer +<var>answer</var>. +</p> +<a name="index-C"></a> +</dd> +<dt><code>-C</code></dt> +<dd><p>Do not discard comments. All comments are passed through to the output +file, except for comments in processed directives, which are deleted +along with the directive. +</p> +<p>You should be prepared for side effects when using <samp>-C</samp>; it +causes the preprocessor to treat comments as tokens in their own right. +For example, comments appearing at the start of what would be a +directive line have the effect of turning that line into an ordinary +source line, since the first token on the line is no longer a ‘<samp>#</samp>’. +</p> +<a name="index-CC"></a> +</dd> +<dt><code>-CC</code></dt> +<dd><p>Do not discard comments, including during macro expansion. This is +like <samp>-C</samp>, except that comments contained within macros are +also passed through to the output file where the macro is expanded. +</p> +<p>In addition to the side effects of the <samp>-C</samp> option, the +<samp>-CC</samp> option causes all C++-style comments inside a macro +to be converted to C-style comments. This is to prevent later use +of that macro from inadvertently commenting out the remainder of +the source line. +</p> +<p>The <samp>-CC</samp> option is generally used to support lint comments. +</p> +<a name="index-P"></a> +</dd> +<dt><code>-P</code></dt> +<dd><p>Inhibit generation of linemarkers in the output from the preprocessor. +This might be useful when running the preprocessor on something that is +not C code, and will be sent to a program which might be confused by the +linemarkers. +</p> +<a name="index-traditional-C-language"></a> +<a name="index-C-language_002c-traditional"></a> +<a name="index-traditional_002dcpp"></a> +<a name="index-traditional"></a> +</dd> +<dt><code>-traditional</code></dt> +<dt><code>-traditional-cpp</code></dt> +<dd> +<p>Try to imitate the behavior of pre-standard C preprocessors, as +opposed to ISO C preprocessors. +See the GNU CPP manual for details. +</p> +<p>Note that GCC does not otherwise attempt to emulate a pre-standard +C compiler, and these options are only supported with the <samp>-E</samp> +switch, or when invoking CPP explicitly. +</p> +<a name="index-trigraphs"></a> +</dd> +<dt><code>-trigraphs</code></dt> +<dd><p>Support ISO C trigraphs. +These are three-character sequences, all starting with ‘<samp>??</samp>’, that +are defined by ISO C to stand for single characters. For example, +‘<samp>??/</samp>’ stands for ‘<samp>\</samp>’, so ‘<samp>'??/n'</samp>’ is a character +constant for a newline. +</p> +<p>The nine trigraphs and their replacements are +</p> +<div class="smallexample"> +<pre class="smallexample">Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??- +Replacement: [ ] { } # \ ^ | ~ +</pre></div> + +<p>By default, GCC ignores trigraphs, but in +standard-conforming modes it converts them. See the <samp>-std</samp> and +<samp>-ansi</samp> options. +</p> +<a name="index-remap"></a> +</dd> +<dt><code>-remap</code></dt> +<dd><p>Enable special code to work around file systems which only permit very +short file names, such as MS-DOS. +</p> +<a name="index-H"></a> +</dd> +<dt><code>-H</code></dt> +<dd><p>Print the name of each header file used, in addition to other normal +activities. Each name is indented to show how deep in the +‘<samp>#include</samp>’ stack it is. Precompiled header files are also +printed, even if they are found to be invalid; an invalid precompiled +header file is printed with ‘<samp>...x</samp>’ and a valid one with ‘<samp>...!</samp>’ . +</p> +<a name="index-d"></a> +</dd> +<dt><code>-d<var>letters</var></code></dt> +<dd><p>Says to make debugging dumps during compilation as specified by +<var>letters</var>. The flags documented here are those relevant to the +preprocessor. Other <var>letters</var> are interpreted +by the compiler proper, or reserved for future versions of GCC, and so +are silently ignored. If you specify <var>letters</var> whose behavior +conflicts, the result is undefined. +See <a href="Developer-Options.html#Developer-Options">Developer Options</a>, for more information. +</p> +<dl compact="compact"> +<dd><a name="index-dM"></a> +</dd> +<dt><code>-dM</code></dt> +<dd><p>Instead of the normal output, generate a list of ‘<samp>#define</samp>’ +directives for all the macros defined during the execution of the +preprocessor, including predefined macros. This gives you a way of +finding out what is predefined in your version of the preprocessor. +Assuming you have no file <samp>foo.h</samp>, the command +</p> +<div class="smallexample"> +<pre class="smallexample">touch foo.h; cpp -dM foo.h +</pre></div> + +<p>shows all the predefined macros. +</p> +<p>If you use <samp>-dM</samp> without the <samp>-E</samp> option, <samp>-dM</samp> is +interpreted as a synonym for <samp>-fdump-rtl-mach</samp>. +See <a href="http://gcc.gnu.org/onlinedocs/gcc/Developer-Options.html#Developer-Options">(gcc)Developer Options</a>. +</p> +<a name="index-dD"></a> +</dd> +<dt><code>-dD</code></dt> +<dd><p>Like <samp>-dM</samp> except in two respects: it does <em>not</em> include the +predefined macros, and it outputs <em>both</em> the ‘<samp>#define</samp>’ +directives and the result of preprocessing. Both kinds of output go to +the standard output file. +</p> +<a name="index-dN"></a> +</dd> +<dt><code>-dN</code></dt> +<dd><p>Like <samp>-dD</samp>, but emit only the macro names, not their expansions. +</p> +<a name="index-dI"></a> +</dd> +<dt><code>-dI</code></dt> +<dd><p>Output ‘<samp>#include</samp>’ directives in addition to the result of +preprocessing. +</p> +<a name="index-dU"></a> +</dd> +<dt><code>-dU</code></dt> +<dd><p>Like <samp>-dD</samp> except that only macros that are expanded, or whose +definedness is tested in preprocessor directives, are output; the +output is delayed until the use or test of the macro; and +‘<samp>#undef</samp>’ directives are also output for macros tested but +undefined at the time. +</p></dd> +</dl> + +<a name="index-fdebug_002dcpp"></a> +</dd> +<dt><code>-fdebug-cpp</code></dt> +<dd><p>This option is only useful for debugging GCC. When used from CPP or with +<samp>-E</samp>, it dumps debugging information about location maps. Every +token in the output is preceded by the dump of the map its location +belongs to. +</p> +<p>When used from GCC without <samp>-E</samp>, this option has no effect. +</p> +<a name="index-Wp"></a> +</dd> +<dt><code>-Wp,<var>option</var></code></dt> +<dd><p>You can use <samp>-Wp,<var>option</var></samp> to bypass the compiler driver +and pass <var>option</var> directly through to the preprocessor. If +<var>option</var> contains commas, it is split into multiple options at the +commas. However, many options are modified, translated or interpreted +by the compiler driver before being passed to the preprocessor, and +<samp>-Wp</samp> forcibly bypasses this phase. The preprocessor’s direct +interface is undocumented and subject to change, so whenever possible +you should avoid using <samp>-Wp</samp> and let the driver handle the +options instead. +</p> +<a name="index-Xpreprocessor"></a> +</dd> +<dt><code>-Xpreprocessor <var>option</var></code></dt> +<dd><p>Pass <var>option</var> as an option to the preprocessor. You can use this to +supply system-specific preprocessor options that GCC does not +recognize. +</p> +<p>If you want to pass an option that takes an argument, you must use +<samp>-Xpreprocessor</samp> twice, once for the option and once for the argument. +</p> +<a name="index-no_002dintegrated_002dcpp"></a> +</dd> +<dt><code>-no-integrated-cpp</code></dt> +<dd><p>Perform preprocessing as a separate pass before compilation. +By default, GCC performs preprocessing as an integrated part of +input tokenization and parsing. +If this option is provided, the appropriate language front end +(<code>cc1</code>, <code>cc1plus</code>, or <code>cc1obj</code> for C, C++, +and Objective-C, respectively) is instead invoked twice, +once for preprocessing only and once for actual compilation +of the preprocessed input. +This option may be useful in conjunction with the <samp>-B</samp> or +<samp>-wrapper</samp> options to specify an alternate preprocessor or +perform additional processing of the program source between +normal preprocessing and compilation. +</p> +<a name="index-flarge_002dsource_002dfiles"></a> +</dd> +<dt><code>-flarge-source-files</code></dt> +<dd><p>Adjust GCC to expect large source files, at the expense of slower +compilation and higher memory usage. +</p> +<p>Specifically, GCC normally tracks both column numbers and line numbers +within source files and it normally prints both of these numbers in +diagnostics. However, once it has processed a certain number of source +lines, it stops tracking column numbers and only tracks line numbers. +This means that diagnostics for later lines do not include column numbers. +It also means that options like <samp>-Wmisleading-indentation</samp> cease to work +at that point, although the compiler prints a note if this happens. +Passing <samp>-flarge-source-files</samp> significantly increases the number +of source lines that GCC can process before it stops tracking columns. +</p> +</dd> +</dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Assembler-Options.html#Assembler-Options" accesskey="n" rel="next">Assembler Options</a>, Previous: <a href="Instrumentation-Options.html#Instrumentation-Options" accesskey="p" rel="previous">Instrumentation Options</a>, Up: <a href="Invoking-GCC.html#Invoking-GCC" accesskey="u" rel="up">Invoking GCC</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |