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Commit 1c5dd43f by Zack Weinberg Committed by Zack Weinberg
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cpp.texi: Formatting corrections. 

* doc/cpp.texi: Formatting corrections.
Correct buggy example of use of __GNUC__ etc.
Clarify $ in identifiers.
* doc/cpp.1: Regenerate.

From-SVN: r43404
parent 76791f3d
Showing with 426 additions and 467 deletions
gcc/ChangeLog
2001-06-15 Zack Weinberg <zackw@stanford.edu>
* doc/cpp.texi: Formatting corrections.
Correct buggy example of use of __GNUC__ etc.
Clarify $ in identifiers.
* doc/cpp.1: Regenerate.
Fri Jun 15 19:35:38 CEST 2001 Jan Hubicka <jh@suse.cz> Fri Jun 15 19:35:38 CEST 2001 Jan Hubicka <jh@suse.cz>
* optabs.c (expand_twoval_binop): Avoid undefined behaviour. * optabs.c (expand_twoval_binop): Avoid undefined behaviour.
......
gcc/doc/cpp.1
.\" Automatically generated by Pod::Man version 1.16 .\" Automatically generated by Pod::Man version 1.16
.\" Fri Jun 15 00:04:02 2001 .\" Fri Jun 15 10:40:40 2001
.\" .\"
.\" Standard preamble: .\" Standard preamble:
.\" ====================================================================== .\" ======================================================================
...@@ -180,7 +180,7 @@ Wherever possible, you should use a preprocessor geared to the language ...@@ -180,7 +180,7 @@ Wherever possible, you should use a preprocessor geared to the language
you are writing in. Modern versions of the \s-1GNU\s0 assembler have macro you are writing in. Modern versions of the \s-1GNU\s0 assembler have macro
facilities. Most high level programming languages have their own facilities. Most high level programming languages have their own
conditional compilation and inclusion mechanism. If all else fails, conditional compilation and inclusion mechanism. If all else fails,
try a true general text processor, such as \f(CW@docref\fR{M4}. try a true general text processor, such as \s-1GNU\s0 M4.
.PP .PP
C preprocessors vary in some details. This manual discusses the \s-1GNU\s0 C C preprocessors vary in some details. This manual discusses the \s-1GNU\s0 C
preprocessor, which provides a small superset of the features of \s-1ISO\s0 preprocessor, which provides a small superset of the features of \s-1ISO\s0
...@@ -208,12 +208,10 @@ appear immediately after the option letter, or with a space between ...@@ -208,12 +208,10 @@ appear immediately after the option letter, or with a space between
option and argument: \fB\-Ifoo\fR and \fB\-I foo\fR have the same option and argument: \fB\-Ifoo\fR and \fB\-I foo\fR have the same
effect. Long options that take arguments require a space between option effect. Long options that take arguments require a space between option
and argument. and argument.
.if n .Ip "\f(CW""\-D \f(CIname\f(CW""\fR" 4 .Ip "\fB\-D\fR \fIname\fR" 4
.el .Ip "\f(CW\-D \f(CIname\f(CW\fR" 4
.IX Item "-D name" .IX Item "-D name"
Predefine \fIname\fR as a macro, with definition \fB1\fR. Predefine \fIname\fR as a macro, with definition \f(CW\*(C`1\*(C'\fR.
.if n .Ip "\f(CW""\-D \f(CIname\f(CW=\f(CIdefinition\f(CW""\fR" 4 .Ip "\fB\-D\fR \fIname\fR\fB=\fR\fIdefinition\fR" 4
.el .Ip "\f(CW\-D \f(CIname\f(CW=\f(CIdefinition\f(CW\fR" 4
.IX Item "-D name=definition" .IX Item "-D name=definition"
Predefine \fIname\fR as a macro, with definition \fIdefinition\fR. Predefine \fIname\fR as a macro, with definition \fIdefinition\fR.
There are no restrictions on the contents of \fIdefinition\fR, but if There are no restrictions on the contents of \fIdefinition\fR, but if
...@@ -228,21 +226,18 @@ its argument list with surrounding parentheses before the equals sign ...@@ -228,21 +226,18 @@ its argument list with surrounding parentheses before the equals sign
(if any). Parentheses are meaningful to most shells, so you will need (if any). Parentheses are meaningful to most shells, so you will need
to quote the option. With \fBsh\fR and \fBcsh\fR, to quote the option. With \fBsh\fR and \fBcsh\fR,
\&\fB\-D'\fR\fIname\fR\fB(\fR\fIargs...\fR\fB)=\fR\fIdefinition\fR\fB'\fR works. \&\fB\-D'\fR\fIname\fR\fB(\fR\fIargs...\fR\fB)=\fR\fIdefinition\fR\fB'\fR works.
.if n .Ip "\f(CW""\-U \f(CIname\f(CW""\fR" 4 .Ip "\fB\-U\fR \fIname\fR" 4
.el .Ip "\f(CW\-U \f(CIname\f(CW\fR" 4
.IX Item "-U name" .IX Item "-U name"
Cancel any previous definition of \fIname\fR, either built in or Cancel any previous definition of \fIname\fR, either built in or
provided with a \fB\-D\fR option. provided with a \fB\-D\fR option.
.Sp .Sp
All \fB\-imacros\fR \fIfile\fR and \fB\-include\fR \fIfile\fR options All \fB\-imacros\fR \fIfile\fR and \fB\-include\fR \fIfile\fR options
are processed after all \fB\-D\fR and \fB\-U\fR options. are processed after all \fB\-D\fR and \fB\-U\fR options.
.if n .Ip "\f(CW""\-undef""\fR" 4 .Ip "\fB\-undef\fR" 4
.el .Ip "\f(CW\-undef\fR" 4
.IX Item "-undef" .IX Item "-undef"
Do not predefine any system-specific macros. The common predefined Do not predefine any system-specific macros. The common predefined
macros remain defined. macros remain defined.
.if n .Ip "\f(CW""\-I \f(CIdir\f(CW""\fR" 4 .Ip "\fB\-I\fR \fIdir\fR" 4
.el .Ip "\f(CW\-I \f(CIdir\f(CW\fR" 4
.IX Item "-I dir" .IX Item "-I dir"
Add the directory \fIdir\fR to the list of directories to be searched Add the directory \fIdir\fR to the list of directories to be searched
for header files. Directories named by \fB\-I\fR for header files. Directories named by \fB\-I\fR
...@@ -252,89 +247,75 @@ It is dangerous to specify a standard system include directory in an ...@@ -252,89 +247,75 @@ It is dangerous to specify a standard system include directory in an
\&\fB\-I\fR option. This defeats the special treatment of system \&\fB\-I\fR option. This defeats the special treatment of system
headers. It can also defeat the repairs to headers. It can also defeat the repairs to
buggy system headers which \s-1GCC\s0 makes when it is installed. buggy system headers which \s-1GCC\s0 makes when it is installed.
.if n .Ip "\f(CW""\-o \f(CIfile\f(CW""\fR" 4 .Ip "\fB\-o\fR \fIfile\fR" 4
.el .Ip "\f(CW\-o \f(CIfile\f(CW\fR" 4
.IX Item "-o file" .IX Item "-o file"
Write output to \fIfile\fR. This is the same as specifying \fIfile\fR Write output to \fIfile\fR. This is the same as specifying \fIfile\fR
as the second non-option argument to \fBcpp\fR. \fBgcc\fR has a as the second non-option argument to \fBcpp\fR. \fBgcc\fR has a
different interpretation of a second non-option argument, so you must different interpretation of a second non-option argument, so you must
use \fB\-o\fR to specify the output file. use \fB\-o\fR to specify the output file.
.if n .Ip "\f(CW""\-Wall""\fR" 4 .Ip "\fB\-Wall\fR" 4
.el .Ip "\f(CW\-Wall\fR" 4
.IX Item "-Wall" .IX Item "-Wall"
Turns on all optional warnings which are desirable for normal code. At Turns on all optional warnings which are desirable for normal code. At
present this is \fB\-Wcomment\fR and \fB\-Wtrigraphs\fR. Note that present this is \fB\-Wcomment\fR and \fB\-Wtrigraphs\fR. Note that
many of the preprocessor's warnings are on by default and have no many of the preprocessor's warnings are on by default and have no
options to control them. options to control them.
.if n .Ip "\f(CW""\-Wcomment""\fR" 4 .Ip "\fB\-Wcomment\fR" 4
.el .Ip "\f(CW\-Wcomment\fR" 4
.IX Item "-Wcomment" .IX Item "-Wcomment"
.PD 0 .PD 0
.if n .Ip "\f(CW""\-Wcomments""\fR" 4 .Ip "\fB\-Wcomments\fR" 4
.el .Ip "\f(CW\-Wcomments\fR" 4
.IX Item "-Wcomments" .IX Item "-Wcomments"
.PD .PD
Warn whenever a comment-start sequence \fB/*\fR appears in a \fB/*\fR Warn whenever a comment-start sequence \fB/*\fR appears in a \fB/*\fR
comment, or whenever a backslash-newline appears in a \fB//\fR comment. comment, or whenever a backslash-newline appears in a \fB//\fR comment.
(Both forms have the same effect.) (Both forms have the same effect.)
.if n .Ip "\f(CW""\-Wtrigraphs""\fR" 4 .Ip "\fB\-Wtrigraphs\fR" 4
.el .Ip "\f(CW\-Wtrigraphs\fR" 4
.IX Item "-Wtrigraphs" .IX Item "-Wtrigraphs"
Warn if any trigraphs are encountered. This option used to take effect Warn if any trigraphs are encountered. This option used to take effect
only if \fB\-trigraphs\fR was also specified, but now works only if \fB\-trigraphs\fR was also specified, but now works
independently. Warnings are not given for trigraphs within comments, as independently. Warnings are not given for trigraphs within comments, as
they do not affect the meaning of the program. they do not affect the meaning of the program.
.if n .Ip "\f(CW""\-Wtraditional""\fR" 4 .Ip "\fB\-Wtraditional\fR" 4
.el .Ip "\f(CW\-Wtraditional\fR" 4
.IX Item "-Wtraditional" .IX Item "-Wtraditional"
Warn about certain constructs that behave differently in traditional and Warn about certain constructs that behave differently in traditional and
\&\s-1ISO\s0 C. Also warn about \s-1ISO\s0 C constructs that have no traditional C \&\s-1ISO\s0 C. Also warn about \s-1ISO\s0 C constructs that have no traditional C
equivalent, and problematic constructs which should be avoided. equivalent, and problematic constructs which should be avoided.
.if n .Ip "\f(CW""\-Wimport""\fR" 4 .Ip "\fB\-Wimport\fR" 4
.el .Ip "\f(CW\-Wimport\fR" 4
.IX Item "-Wimport" .IX Item "-Wimport"
Warn the first time \fB#import\fR is used. Warn the first time \fB#import\fR is used.
.if n .Ip "\f(CW""\-Wundef""\fR" 4 .Ip "\fB\-Wundef\fR" 4
.el .Ip "\f(CW\-Wundef\fR" 4
.IX Item "-Wundef" .IX Item "-Wundef"
Warn whenever an identifier which is not a macro is encountered in an Warn whenever an identifier which is not a macro is encountered in an
\&\fB#if\fR directive, outside of \fBdefined\fR. Such identifiers are \&\fB#if\fR directive, outside of \fBdefined\fR. Such identifiers are
replaced with zero. replaced with zero.
.if n .Ip "\f(CW""\-Werror""\fR" 4 .Ip "\fB\-Werror\fR" 4
.el .Ip "\f(CW\-Werror\fR" 4
.IX Item "-Werror" .IX Item "-Werror"
Make all warnings into hard errors. Source code which triggers warnings Make all warnings into hard errors. Source code which triggers warnings
will be rejected. will be rejected.
.if n .Ip "\f(CW""\-Wsystem\-headers""\fR" 4 .Ip "\fB\-Wsystem-headers\fR" 4
.el .Ip "\f(CW\-Wsystem\-headers\fR" 4
.IX Item "-Wsystem-headers" .IX Item "-Wsystem-headers"
Issue warnings for code in system headers. These are normally unhelpful Issue warnings for code in system headers. These are normally unhelpful
in finding bugs in your own code, therefore suppressed. If you are in finding bugs in your own code, therefore suppressed. If you are
responsible for the system library, you may want to see them. responsible for the system library, you may want to see them.
.if n .Ip "\f(CW""\-w""\fR" 4 .Ip "\fB\-w\fR" 4
.el .Ip "\f(CW\-w\fR" 4
.IX Item "-w" .IX Item "-w"
Suppress all warnings, including those which \s-1GNU\s0 \s-1CPP\s0 issues by default. Suppress all warnings, including those which \s-1GNU\s0 \s-1CPP\s0 issues by default.
.if n .Ip "\f(CW""\-pedantic""\fR" 4 .Ip "\fB\-pedantic\fR" 4
.el .Ip "\f(CW\-pedantic\fR" 4
.IX Item "-pedantic" .IX Item "-pedantic"
Issue all the mandatory diagnostics listed in the C standard. Some of Issue all the mandatory diagnostics listed in the C standard. Some of
them are left out by default, since they trigger frequently on harmless them are left out by default, since they trigger frequently on harmless
code. code.
.if n .Ip "\f(CW""\-pedantic\-errors""\fR" 4 .Ip "\fB\-pedantic-errors\fR" 4
.el .Ip "\f(CW\-pedantic\-errors\fR" 4
.IX Item "-pedantic-errors" .IX Item "-pedantic-errors"
Issue all the mandatory diagnostics, and make all mandatory diagnostics Issue all the mandatory diagnostics, and make all mandatory diagnostics
into errors. This includes mandatory diagnostics that \s-1GCC\s0 issues into errors. This includes mandatory diagnostics that \s-1GCC\s0 issues
without \fB\-pedantic\fR but treats as warnings. without \fB\-pedantic\fR but treats as warnings.
.if n .Ip "\f(CW""\-M""\fR" 4 .Ip "\fB\-M\fR" 4
.el .Ip "\f(CW\-M\fR" 4
.IX Item "-M" .IX Item "-M"
Instead of outputting the result of preprocessing, output a rule Instead of outputting the result of preprocessing, output a rule
suitable for \f(CW\*(C`make\*(C'\fR describing the dependencies of the main source suitable for \fBmake\fR describing the dependencies of the main
file. The preprocessor outputs one \f(CW\*(C`make\*(C'\fR rule containing the source file. The preprocessor outputs one \fBmake\fR rule containing
object file name for that source file, a colon, and the names of all the the object file name for that source file, a colon, and the names of all
included files, including those coming from \fB\-include\fR or the included files, including those coming from \fB\-include\fR or
\&\fB\-imacros\fR command line options. \&\fB\-imacros\fR command line options.
.Sp .Sp
Unless specified explicitly (with \fB\-MT\fR or \fB\-MQ\fR), the Unless specified explicitly (with \fB\-MT\fR or \fB\-MQ\fR), the
...@@ -342,22 +323,18 @@ object file name consists of the basename of the source file with any ...@@ -342,22 +323,18 @@ object file name consists of the basename of the source file with any
suffix replaced with object file suffix. If there are many included suffix replaced with object file suffix. If there are many included
files then the rule is split into several lines using \fB\e\fR\-newline. files then the rule is split into several lines using \fB\e\fR\-newline.
The rule has no commands. The rule has no commands.
.if n .Ip "\f(CW""\-MM""\fR" 4 .Ip "\fB\-MM\fR" 4
.el .Ip "\f(CW\-MM\fR" 4
.IX Item "-MM" .IX Item "-MM"
Like \fB\-M\fR, but mention only the files included with \fB#include Like \fB\-M\fR, but mention only the files included with \f(CW\*(C`#include\ "\f(CIfile\f(CW"\*(C'\fR or with \fB\-include\fR or \fB\-imacros\fR command line
"\fR\fIfile\fR\fB"\fR or with \fB\-include\fR or \fB\-imacros\fR command line options. System header files included with \f(CW\*(C`#include\ <\f(CIfile\f(CW>\*(C'\fR
options. System header files included with \fB#include <\fR\fIfile\fR\fB>\fR
are omitted. are omitted.
.if n .Ip "\f(CW""\-MF \f(CIfile\f(CW""\fR" 4 .Ip "\fB\-MF\fR \fIfile\fR" 4
.el .Ip "\f(CW\-MF \f(CIfile\f(CW\fR" 4
.IX Item "-MF file" .IX Item "-MF file"
When used with \fB\-M\fR or \fB\-MM\fR, specifies a file to write the When used with \fB\-M\fR or \fB\-MM\fR, specifies a file to write the
dependencies to. This allows the preprocessor to write the preprocessed dependencies to. This allows the preprocessor to write the preprocessed
file to stdout normally. If no \fB\-MF\fR switch is given, \s-1CPP\s0 sends file to stdout normally. If no \fB\-MF\fR switch is given, \s-1CPP\s0 sends
the rules to stdout and suppresses normal preprocessed output. the rules to stdout and suppresses normal preprocessed output.
.if n .Ip "\f(CW""\-MG""\fR" 4 .Ip "\fB\-MG\fR" 4
.el .Ip "\f(CW\-MG\fR" 4
.IX Item "-MG" .IX Item "-MG"
When used with \fB\-M\fR or \fB\-MM\fR, \fB\-MG\fR says to treat missing When used with \fB\-M\fR or \fB\-MM\fR, \fB\-MG\fR says to treat missing
header files as generated files and assume they live in the same header files as generated files and assume they live in the same
...@@ -365,13 +342,12 @@ directory as the source file. It suppresses preprocessed output, as a ...@@ -365,13 +342,12 @@ directory as the source file. It suppresses preprocessed output, as a
missing header file is ordinarily an error. missing header file is ordinarily an error.
.Sp .Sp
This feature is used in automatic updating of makefiles. This feature is used in automatic updating of makefiles.
.if n .Ip "\f(CW""\-MP""\fR" 4 .Ip "\fB\-MP\fR" 4
.el .Ip "\f(CW\-MP\fR" 4
.IX Item "-MP" .IX Item "-MP"
This option instructs \s-1CPP\s0 to add a phony target for each dependency This option instructs \s-1CPP\s0 to add a phony target for each dependency
other than the main file, causing each to depend on nothing. These other than the main file, causing each to depend on nothing. These
dummy rules work around errors \f(CW\*(C`make\*(C'\fR gives if you remove header dummy rules work around errors \fBmake\fR gives if you remove header
files without updating the \f(CW\*(C`Makefile\*(C'\fR to match. files without updating the \fIMakefile\fR to match.
.Sp .Sp
This is typical output: This is typical output:
.Sp .Sp
...@@ -381,8 +357,7 @@ This is typical output: ...@@ -381,8 +357,7 @@ This is typical output:
.Vb 1 .Vb 1
\& test.h: \& test.h:
.Ve .Ve
.if n .Ip "\f(CW""\-MT \f(CItarget\f(CW""\fR" 4 .Ip "\fB\-MT\fR \fItarget\fR" 4
.el .Ip "\f(CW\-MT \f(CItarget\f(CW\fR" 4
.IX Item "-MT target" .IX Item "-MT target"
Change the target of the rule emitted by dependency generation. By Change the target of the rule emitted by dependency generation. By
default \s-1CPP\s0 takes the name of the main input file, including any path, default \s-1CPP\s0 takes the name of the main input file, including any path,
...@@ -398,8 +373,7 @@ For example, \fB\-MT\ '$(objpfx)foo.o'\fR might give ...@@ -398,8 +373,7 @@ For example, \fB\-MT\ '$(objpfx)foo.o'\fR might give
.Vb 1 .Vb 1
\& $(objpfx)foo.o: foo.c \& $(objpfx)foo.o: foo.c
.Ve .Ve
.if n .Ip "\f(CW""\-MQ \f(CItarget\f(CW""\fR" 4 .Ip "\fB\-MQ\fR \fItarget\fR" 4
.el .Ip "\f(CW\-MQ \f(CItarget\f(CW\fR" 4
.IX Item "-MQ target" .IX Item "-MQ target"
Same as \fB\-MT\fR, but it quotes any characters which are special to Same as \fB\-MT\fR, but it quotes any characters which are special to
Make. \fB\-MQ\ '$(objpfx)foo.o'\fR gives Make. \fB\-MQ\ '$(objpfx)foo.o'\fR gives
...@@ -409,12 +383,10 @@ Make. \fB\-MQ\ '$(objpfx)foo.o'\fR gives ...@@ -409,12 +383,10 @@ Make. \fB\-MQ\ '$(objpfx)foo.o'\fR gives
.Ve .Ve
The default target is automatically quoted, as if it were given with The default target is automatically quoted, as if it were given with
\&\fB\-MQ\fR. \&\fB\-MQ\fR.
.if n .Ip "\f(CW""\-MD \f(CIfile\f(CW""\fR" 4 .Ip "\fB\-MD\fR \fIfile\fR" 4
.el .Ip "\f(CW\-MD \f(CIfile\f(CW\fR" 4
.IX Item "-MD file" .IX Item "-MD file"
.PD 0 .PD 0
.if n .Ip "\f(CW""\-MMD \f(CIfile\f(CW""\fR" 4 .Ip "\fB\-MMD\fR \fIfile\fR" 4
.el .Ip "\f(CW\-MMD \f(CIfile\f(CW\fR" 4
.IX Item "-MMD file" .IX Item "-MMD file"
.PD .PD
\&\fB\-MD\fR \fIfile\fR is equivalent to \fB\-M \-MF\fR \fIfile\fR, and \&\fB\-MD\fR \fIfile\fR is equivalent to \fB\-M \-MF\fR \fIfile\fR, and
...@@ -423,18 +395,14 @@ The default target is automatically quoted, as if it were given with ...@@ -423,18 +395,14 @@ The default target is automatically quoted, as if it were given with
Due to limitations in the compiler driver, you must use these switches Due to limitations in the compiler driver, you must use these switches
when you want to generate a dependency file as a side-effect of normal when you want to generate a dependency file as a side-effect of normal
compilation. compilation.
.if n .Ip "\f(CW""\-x c""\fR" 4 .Ip "\fB\-x c\fR" 4
.el .Ip "\f(CW\-x c\fR" 4
.IX Item "-x c" .IX Item "-x c"
.PD 0 .PD 0
.if n .Ip "\f(CW""\-x c++""\fR" 4 .Ip "\fB\-x c++\fR" 4
.el .Ip "\f(CW\-x c++\fR" 4
.IX Item "-x c++" .IX Item "-x c++"
.if n .Ip "\f(CW""\-x objective\-c""\fR" 4 .Ip "\fB\-x objective-c\fR" 4
.el .Ip "\f(CW\-x objective\-c\fR" 4
.IX Item "-x objective-c" .IX Item "-x objective-c"
.if n .Ip "\f(CW""\-x assembler\-with\-cpp""\fR" 4 .Ip "\fB\-x assembler-with-cpp\fR" 4
.el .Ip "\f(CW\-x assembler\-with\-cpp\fR" 4
.IX Item "-x assembler-with-cpp" .IX Item "-x assembler-with-cpp"
.PD .PD
Specify the source language: C, \*(C+, Objective-C, or assembly. This has Specify the source language: C, \*(C+, Objective-C, or assembly. This has
...@@ -450,12 +418,10 @@ generic mode. ...@@ -450,12 +418,10 @@ generic mode.
which selected both the language and the standards conformance level. which selected both the language and the standards conformance level.
This option has been removed, because it conflicts with the \fB\-l\fR This option has been removed, because it conflicts with the \fB\-l\fR
option. option.
.if n .Ip "\f(CW""\-std=\f(CIstandard\f(CW""\fR" 4 .Ip "\fB\-std=\fR\fIstandard\fR" 4
.el .Ip "\f(CW\-std=\f(CIstandard\f(CW\fR" 4
.IX Item "-std=standard" .IX Item "-std=standard"
.PD 0 .PD 0
.if n .Ip "\f(CW""\-ansi""\fR" 4 .Ip "\fB\-ansi\fR" 4
.el .Ip "\f(CW\-ansi\fR" 4
.IX Item "-ansi" .IX Item "-ansi"
.PD .PD
Specify the standard to which the code should conform. Currently cpp Specify the standard to which the code should conform. Currently cpp
...@@ -465,11 +431,11 @@ added in the future. ...@@ -465,11 +431,11 @@ added in the future.
\&\fIstandard\fR \&\fIstandard\fR
may be one of: may be one of:
.RS 4 .RS 4
.if n .Ip "\f(CW""iso9899:1990""\fR" 4 .if n .Ip "\f(CW""""iso9899:1990""""\fR" 4
.el .Ip "\f(CWiso9899:1990\fR" 4 .el .Ip "\f(CWiso9899:1990\fR" 4
.IX Item "iso9899:1990" .IX Item "iso9899:1990"
.PD 0 .PD 0
.if n .Ip "\f(CW""c89""\fR" 4 .if n .Ip "\f(CW""""c89""""\fR" 4
.el .Ip "\f(CWc89\fR" 4 .el .Ip "\f(CWc89\fR" 4
.IX Item "c89" .IX Item "c89"
.PD .PD
...@@ -477,35 +443,35 @@ The \s-1ISO\s0 C standard from 1990. \fBc89\fR is the customary shorthand for ...@@ -477,35 +443,35 @@ The \s-1ISO\s0 C standard from 1990. \fBc89\fR is the customary shorthand for
this version of the standard. this version of the standard.
.Sp .Sp
The \fB\-ansi\fR option is equivalent to \fB\-std=c89\fR. The \fB\-ansi\fR option is equivalent to \fB\-std=c89\fR.
.if n .Ip "\f(CW""iso9899:199409""\fR" 4 .if n .Ip "\f(CW""""iso9899:199409""""\fR" 4
.el .Ip "\f(CWiso9899:199409\fR" 4 .el .Ip "\f(CWiso9899:199409\fR" 4
.IX Item "iso9899:199409" .IX Item "iso9899:199409"
The 1990 C standard, as amended in 1994. The 1990 C standard, as amended in 1994.
.if n .Ip "\f(CW""iso9899:1999""\fR" 4 .if n .Ip "\f(CW""""iso9899:1999""""\fR" 4
.el .Ip "\f(CWiso9899:1999\fR" 4 .el .Ip "\f(CWiso9899:1999\fR" 4
.IX Item "iso9899:1999" .IX Item "iso9899:1999"
.PD 0 .PD 0
.if n .Ip "\f(CW""c99""\fR" 4 .if n .Ip "\f(CW""""c99""""\fR" 4
.el .Ip "\f(CWc99\fR" 4 .el .Ip "\f(CWc99\fR" 4
.IX Item "c99" .IX Item "c99"
.if n .Ip "\f(CW""iso9899:199x""\fR" 4 .if n .Ip "\f(CW""""iso9899:199x""""\fR" 4
.el .Ip "\f(CWiso9899:199x\fR" 4 .el .Ip "\f(CWiso9899:199x\fR" 4
.IX Item "iso9899:199x" .IX Item "iso9899:199x"
.if n .Ip "\f(CW""c9x""\fR" 4 .if n .Ip "\f(CW""""c9x""""\fR" 4
.el .Ip "\f(CWc9x\fR" 4 .el .Ip "\f(CWc9x\fR" 4
.IX Item "c9x" .IX Item "c9x"
.PD .PD
The revised \s-1ISO\s0 C standard, published in December 1999. Before The revised \s-1ISO\s0 C standard, published in December 1999. Before
publication, this was known as C9X. publication, this was known as C9X.
.if n .Ip "\f(CW""gnu89""\fR" 4 .if n .Ip "\f(CW""""gnu89""""\fR" 4
.el .Ip "\f(CWgnu89\fR" 4 .el .Ip "\f(CWgnu89\fR" 4
.IX Item "gnu89" .IX Item "gnu89"
The 1990 C standard plus \s-1GNU\s0 extensions. This is the default. The 1990 C standard plus \s-1GNU\s0 extensions. This is the default.
.if n .Ip "\f(CW""gnu99""\fR" 4 .if n .Ip "\f(CW""""gnu99""""\fR" 4
.el .Ip "\f(CWgnu99\fR" 4 .el .Ip "\f(CWgnu99\fR" 4
.IX Item "gnu99" .IX Item "gnu99"
.PD 0 .PD 0
.if n .Ip "\f(CW""gnu9x""\fR" 4 .if n .Ip "\f(CW""""gnu9x""""\fR" 4
.el .Ip "\f(CWgnu9x\fR" 4 .el .Ip "\f(CWgnu9x\fR" 4
.IX Item "gnu9x" .IX Item "gnu9x"
.PD .PD
...@@ -513,32 +479,28 @@ The 1999 C standard plus \s-1GNU\s0 extensions. ...@@ -513,32 +479,28 @@ The 1999 C standard plus \s-1GNU\s0 extensions.
.RE .RE
.RS 4 .RS 4
.RE .RE
.if n .Ip "\f(CW""\-I\-""\fR" 4 .Ip "\fB\-I-\fR" 4
.el .Ip "\f(CW\-I\-\fR" 4
.IX Item "-I-" .IX Item "-I-"
Split the include path. Any directories specified with \fB\-I\fR Split the include path. Any directories specified with \fB\-I\fR
options before \fB\-I-\fR are searched only for headers requested with options before \fB\-I-\fR are searched only for headers requested with
\&\fB#include\ "\f(BIfile\fB"\fR; they are not searched for \&\f(CW\*(C`#include\ "\f(CIfile\f(CW"\*(C'\fR; they are not searched for
\&\fB#include\ <\f(BIfile\fB>\fR. If additional directories are \&\f(CW\*(C`#include\ <\f(CIfile\f(CW>\*(C'\fR. If additional directories are
specified with \fB\-I\fR options after the \fB\-I-\fR, those specified with \fB\-I\fR options after the \fB\-I-\fR, those
directories are searched for all \fB#include\fR directives. directories are searched for all \fB#include\fR directives.
.Sp .Sp
In addition, \fB\-I-\fR inhibits the use of the directory of the current In addition, \fB\-I-\fR inhibits the use of the directory of the current
file directory as the first search directory for \fB#include\ "\f(BIfile\fB"\fR. file directory as the first search directory for \f(CW\*(C`#include\ "\f(CIfile\f(CW"\*(C'\fR.
.if n .Ip "\f(CW""\-nostdinc""\fR" 4 .Ip "\fB\-nostdinc\fR" 4
.el .Ip "\f(CW\-nostdinc\fR" 4
.IX Item "-nostdinc" .IX Item "-nostdinc"
Do not search the standard system directories for header files. Do not search the standard system directories for header files.
Only the directories you have specified with \fB\-I\fR options Only the directories you have specified with \fB\-I\fR options
(and the directory of the current file, if appropriate) are searched. (and the directory of the current file, if appropriate) are searched.
.if n .Ip "\f(CW""\-nostdinc++""\fR" 4 .Ip "\fB\-nostdinc++\fR" 4
.el .Ip "\f(CW\-nostdinc++\fR" 4
.IX Item "-nostdinc++" .IX Item "-nostdinc++"
Do not search for header files in the \*(C+\-specific standard directories, Do not search for header files in the \*(C+\-specific standard directories,
but do still search the other standard directories. (This option is but do still search the other standard directories. (This option is
used when building the \*(C+ library.) used when building the \*(C+ library.)
.if n .Ip "\f(CW""\-include \f(CIfile\f(CW""\fR" 4 .Ip "\fB\-include\fR \fIfile\fR" 4
.el .Ip "\f(CW\-include \f(CIfile\f(CW\fR" 4
.IX Item "-include file" .IX Item "-include file"
Process \fIfile\fR as if \f(CW\*(C`#include "file"\*(C'\fR appeared as the first Process \fIfile\fR as if \f(CW\*(C`#include "file"\*(C'\fR appeared as the first
line of the primary source file. However, the first directory searched line of the primary source file. However, the first directory searched
...@@ -549,8 +511,7 @@ chain as normal. ...@@ -549,8 +511,7 @@ chain as normal.
.Sp .Sp
If multiple \fB\-include\fR options are given, the files are included If multiple \fB\-include\fR options are given, the files are included
in the order they appear on the command line. in the order they appear on the command line.
.if n .Ip "\f(CW""\-imacros \f(CIfile\f(CW""\fR" 4 .Ip "\fB\-imacros\fR \fIfile\fR" 4
.el .Ip "\f(CW\-imacros \f(CIfile\f(CW\fR" 4
.IX Item "-imacros file" .IX Item "-imacros file"
Exactly like \fB\-include\fR, except that any output produced by Exactly like \fB\-include\fR, except that any output produced by
scanning \fIfile\fR is thrown away. Macros it defines remain defined. scanning \fIfile\fR is thrown away. Macros it defines remain defined.
...@@ -559,24 +520,20 @@ processing its declarations. ...@@ -559,24 +520,20 @@ processing its declarations.
.Sp .Sp
All files specified by \fB\-imacros\fR are processed before all files All files specified by \fB\-imacros\fR are processed before all files
specified by \fB\-include\fR. specified by \fB\-include\fR.
.if n .Ip "\f(CW""\-idirafter \f(CIdir\f(CW""\fR" 4 .Ip "\fB\-idirafter\fR \fIdir\fR" 4
.el .Ip "\f(CW\-idirafter \f(CIdir\f(CW\fR" 4
.IX Item "-idirafter dir" .IX Item "-idirafter dir"
Search \fIdir\fR for header files, but do it \fIafter\fR all Search \fIdir\fR for header files, but do it \fIafter\fR all
directories specified with \fB\-I\fR and the standard system directories directories specified with \fB\-I\fR and the standard system directories
have been exhausted. \fIdir\fR is treated as a system include directory. have been exhausted. \fIdir\fR is treated as a system include directory.
.if n .Ip "\f(CW""\-iprefix \f(CIprefix\f(CW""\fR" 4 .Ip "\fB\-iprefix\fR \fIprefix\fR" 4
.el .Ip "\f(CW\-iprefix \f(CIprefix\f(CW\fR" 4
.IX Item "-iprefix prefix" .IX Item "-iprefix prefix"
Specify \fIprefix\fR as the prefix for subsequent \fB\-iwithprefix\fR Specify \fIprefix\fR as the prefix for subsequent \fB\-iwithprefix\fR
options. If the prefix represents a directory, you should include the options. If the prefix represents a directory, you should include the
final \fB/\fR. final \fB/\fR.
.if n .Ip "\f(CW""\-iwithprefix \f(CIdir\f(CW""\fR" 4 .Ip "\fB\-iwithprefix\fR \fIdir\fR" 4
.el .Ip "\f(CW\-iwithprefix \f(CIdir\f(CW\fR" 4
.IX Item "-iwithprefix dir" .IX Item "-iwithprefix dir"
.PD 0 .PD 0
.if n .Ip "\f(CW""\-iwithprefixbefore \f(CIdir\f(CW""\fR" 4 .Ip "\fB\-iwithprefixbefore\fR \fIdir\fR" 4
.el .Ip "\f(CW\-iwithprefixbefore \f(CIdir\f(CW\fR" 4
.IX Item "-iwithprefixbefore dir" .IX Item "-iwithprefixbefore dir"
.PD .PD
Append \fIdir\fR to the prefix specified previously with Append \fIdir\fR to the prefix specified previously with
...@@ -585,15 +542,13 @@ path. \fB\-iwithprefixbefore\fR puts it in the same place \fB\-I\fR ...@@ -585,15 +542,13 @@ path. \fB\-iwithprefixbefore\fR puts it in the same place \fB\-I\fR
would; \fB\-iwithprefix\fR puts it where \fB\-idirafter\fR would. would; \fB\-iwithprefix\fR puts it where \fB\-idirafter\fR would.
.Sp .Sp
Use of these options is discouraged. Use of these options is discouraged.
.if n .Ip "\f(CW""\-isystem \f(CIdir\f(CW""\fR" 4 .Ip "\fB\-isystem\fR \fIdir\fR" 4
.el .Ip "\f(CW\-isystem \f(CIdir\f(CW\fR" 4
.IX Item "-isystem dir" .IX Item "-isystem dir"
Search \fIdir\fR for header files, after all directories specified by Search \fIdir\fR for header files, after all directories specified by
\&\fB\-I\fR but before the standard system directories. Mark it \&\fB\-I\fR but before the standard system directories. Mark it
as a system directory, so that it gets the same special treatment as as a system directory, so that it gets the same special treatment as
is applied to the standard system directories. is applied to the standard system directories.
.if n .Ip "\f(CW""\-fpreprocessed""\fR" 4 .Ip "\fB\-fpreprocessed\fR" 4
.el .Ip "\f(CW\-fpreprocessed\fR" 4
.IX Item "-fpreprocessed" .IX Item "-fpreprocessed"
Indicate to the preprocessor that the input file has already been Indicate to the preprocessor that the input file has already been
preprocessed. This suppresses things like macro expansion, trigraph preprocessed. This suppresses things like macro expansion, trigraph
...@@ -605,76 +560,65 @@ for the front ends. ...@@ -605,76 +560,65 @@ for the front ends.
extensions \fB.i\fR, \fB.ii\fR or \fB.mi\fR. These are the extensions \fB.i\fR, \fB.ii\fR or \fB.mi\fR. These are the
extensions that \s-1GCC\s0 uses for preprocessed files created by extensions that \s-1GCC\s0 uses for preprocessed files created by
\&\fB\-save-temps\fR. \&\fB\-save-temps\fR.
.if n .Ip "\f(CW""\-ftabstop=\f(CIwidth\f(CW""\fR" 4 .Ip "\fB\-ftabstop=\fR\fIwidth\fR" 4
.el .Ip "\f(CW\-ftabstop=\f(CIwidth\f(CW\fR" 4
.IX Item "-ftabstop=width" .IX Item "-ftabstop=width"
Set the distance between tab stops. This helps the preprocessor report Set the distance between tab stops. This helps the preprocessor report
correct column numbers in warnings or errors, even if tabs appear on the 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 line. If the value is less than 1 or greater than 100, the option is
ignored. The default is 8. ignored. The default is 8.
.if n .Ip "\f(CW""\-fno\-show\-column""\fR" 4 .Ip "\fB\-fno-show-column\fR" 4
.el .Ip "\f(CW\-fno\-show\-column\fR" 4
.IX Item "-fno-show-column" .IX Item "-fno-show-column"
Do not print column numbers in diagnostics. This may be necessary if Do not print column numbers in diagnostics. This may be necessary if
diagnostics are being scanned by a program that does not understand the diagnostics are being scanned by a program that does not understand the
column numbers, such as \f(CW\*(C`dejagnu\*(C'\fR. column numbers, such as \fBdejagnu\fR.
.if n .Ip "\f(CW""\-A \f(CIpredicate\f(CW=\f(CIanswer\f(CW""\fR" 4 .Ip "\fB\-A\fR \fIpredicate\fR\fB=\fR\fIanswer\fR" 4
.el .Ip "\f(CW\-A \f(CIpredicate\f(CW=\f(CIanswer\f(CW\fR" 4
.IX Item "-A predicate=answer" .IX Item "-A predicate=answer"
Make an assertion with the predicate \fIpredicate\fR and answer Make an assertion with the predicate \fIpredicate\fR and answer
\&\fIanswer\fR. This form is preferred to the older form \fB\-A\fR \&\fIanswer\fR. This form is preferred to the older form \fB\-A\fR
\&\fIpredicate\fR\fB(\fR\fIanswer\fR\fB)\fR, which is still supported, because \&\fIpredicate\fR\fB(\fR\fIanswer\fR\fB)\fR, which is still supported, because
it does not use shell special characters. it does not use shell special characters.
.if n .Ip "\f(CW""\-A \-\f(CIpredicate\f(CW=\f(CIanswer\f(CW""\fR" 4 .Ip "\fB\-A -\fR\fIpredicate\fR\fB=\fR\fIanswer\fR" 4
.el .Ip "\f(CW\-A \-\f(CIpredicate\f(CW=\f(CIanswer\f(CW\fR" 4
.IX Item "-A -predicate=answer" .IX Item "-A -predicate=answer"
Cancel an assertion with the predicate \fIpredicate\fR and answer Cancel an assertion with the predicate \fIpredicate\fR and answer
\&\fIanswer\fR. \&\fIanswer\fR.
.if n .Ip "\f(CW""\-A\-""\fR" 4 .Ip "\fB\-A-\fR" 4
.el .Ip "\f(CW\-A\-\fR" 4
.IX Item "-A-" .IX Item "-A-"
Cancel all predefined assertions and all assertions preceding it on Cancel all predefined assertions and all assertions preceding it on
the command line. Also, undefine all predefined macros and all the command line. Also, undefine all predefined macros and all
macros preceding it on the command line. (This is a historical wart and macros preceding it on the command line. (This is a historical wart and
may change in the future.) may change in the future.)
.if n .Ip "\f(CW""\-dM""\fR" 4 .Ip "\fB\-dM\fR" 4
.el .Ip "\f(CW\-dM\fR" 4
.IX Item "-dM" .IX Item "-dM"
Instead of the normal output, generate a list of \fB#define\fR Instead of the normal output, generate a list of \fB#define\fR
directives for all the macros defined during the execution of the directives for all the macros defined during the execution of the
preprocessor, including predefined macros. This gives you a way of preprocessor, including predefined macros. This gives you a way of
finding out what is predefined in your version of the preprocessor. finding out what is predefined in your version of the preprocessor.
Assuming you have no file \fBfoo.h\fR, the command Assuming you have no file \fIfoo.h\fR, the command
.Sp .Sp
.Vb 1 .Vb 1
\& touch foo.h; cpp -dM foo.h \& touch foo.h; cpp -dM foo.h
.Ve .Ve
will show all the predefined macros. will show all the predefined macros.
.if n .Ip "\f(CW""\-dD""\fR" 4 .Ip "\fB\-dD\fR" 4
.el .Ip "\f(CW\-dD\fR" 4
.IX Item "-dD" .IX Item "-dD"
Like \fB\-dM\fR except in two respects: it does \fInot\fR include the Like \fB\-dM\fR except in two respects: it does \fInot\fR include the
predefined macros, and it outputs \fIboth\fR the \fB#define\fR predefined macros, and it outputs \fIboth\fR the \fB#define\fR
directives and the result of preprocessing. Both kinds of output go to directives and the result of preprocessing. Both kinds of output go to
the standard output file. the standard output file.
.if n .Ip "\f(CW""\-dN""\fR" 4 .Ip "\fB\-dN\fR" 4
.el .Ip "\f(CW\-dN\fR" 4
.IX Item "-dN" .IX Item "-dN"
Like \fB\-dD\fR, but emit only the macro names, not their expansions. Like \fB\-dD\fR, but emit only the macro names, not their expansions.
.if n .Ip "\f(CW""\-dI""\fR" 4 .Ip "\fB\-dI\fR" 4
.el .Ip "\f(CW\-dI\fR" 4
.IX Item "-dI" .IX Item "-dI"
Output \fB#include\fR directives in addition to the result of Output \fB#include\fR directives in addition to the result of
preprocessing. preprocessing.
.if n .Ip "\f(CW""\-P""\fR" 4 .Ip "\fB\-P\fR" 4
.el .Ip "\f(CW\-P\fR" 4
.IX Item "-P" .IX Item "-P"
Inhibit generation of linemarkers in the output from the preprocessor. Inhibit generation of linemarkers in the output from the preprocessor.
This might be useful when running the preprocessor on something that is 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 not C code, and will be sent to a program which might be confused by the
linemarkers. linemarkers.
.if n .Ip "\f(CW""\-C""\fR" 4 .Ip "\fB\-C\fR" 4
.el .Ip "\f(CW\-C\fR" 4
.IX Item "-C" .IX Item "-C"
Do not discard comments. All comments are passed through to the output Do not discard comments. All comments are passed through to the output
file, except for comments in processed directives, which are deleted file, except for comments in processed directives, which are deleted
...@@ -689,64 +633,52 @@ replaced by a single space might become significant when comments are ...@@ -689,64 +633,52 @@ replaced by a single space might become significant when comments are
retained. Also, comments appearing at the start of what would be a retained. Also, comments appearing at the start of what would be a
directive line have the effect of turning that line into an ordinary 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 \fB#\fR. source line, since the first token on the line is no longer a \fB#\fR.
.if n .Ip "\f(CW""\-gcc""\fR" 4 .Ip "\fB\-gcc\fR" 4
.el .Ip "\f(CW\-gcc\fR" 4
.IX Item "-gcc" .IX Item "-gcc"
Define the macros _\|_GNUC_\|_, _\|_GNUC_MINOR_\|_ and Define the macros _\|_GNUC_\|_, _\|_GNUC_MINOR_\|_ and
_\|_GNUC_PATCHLEVEL_\|_. These are defined automatically when you use _\|_GNUC_PATCHLEVEL_\|_. These are defined automatically when you use
\&\fBgcc \-E\fR; you can turn them off in that case with \fB\-no-gcc\fR. \&\fBgcc \-E\fR; you can turn them off in that case with
.if n .Ip "\f(CW""\-traditional""\fR" 4 \&\fB\-no-gcc\fR.
.el .Ip "\f(CW\-traditional\fR" 4 .Ip "\fB\-traditional\fR" 4
.IX Item "-traditional" .IX Item "-traditional"
Try to imitate the behavior of old-fashioned C, as opposed to \s-1ISO\s0 Try to imitate the behavior of old-fashioned C, as opposed to \s-1ISO\s0
C. C.
.if n .Ip "\f(CW""\-trigraphs""\fR" 4 .Ip "\fB\-trigraphs\fR" 4
.el .Ip "\f(CW\-trigraphs\fR" 4
.IX Item "-trigraphs" .IX Item "-trigraphs"
Process trigraph sequences. Process trigraph sequences.
.if n .Ip "\f(CW""\-remap""\fR" 4 .Ip "\fB\-remap\fR" 4
.el .Ip "\f(CW\-remap\fR" 4
.IX Item "-remap" .IX Item "-remap"
Enable special code to work around file systems which only permit very Enable special code to work around file systems which only permit very
short file names, such as \s-1MS-DOS\s0. short file names, such as \s-1MS-DOS\s0.
.if n .Ip "\f(CW""\-$""\fR" 4 .Ip "\fB\-$\fR" 4
.el .Ip "\f(CW\-$\fR" 4
.IX Item "-$" .IX Item "-$"
Forbid the use of \fB$\fR in identifiers. The C standard allows Forbid the use of \fB$\fR in identifiers. The C standard allows
implementations to define extra characters that can appear in implementations to define extra characters that can appear in
identifiers. By default the \s-1GNU\s0 C preprocessor permits \fB$\fR, a identifiers. By default \s-1GNU\s0 \s-1CPP\s0 permits \fB$\fR, a common extension.
common extension. .Ip "\fB\-h\fR" 4
.if n .Ip "\f(CW""\-h""\fR" 4
.el .Ip "\f(CW\-h\fR" 4
.IX Item "-h" .IX Item "-h"
.PD 0 .PD 0
.if n .Ip "\f(CW""\-\-help""\fR" 4 .Ip "\fB\*(--help\fR" 4
.el .Ip "\f(CW\-\-help\fR" 4 .IX Item "help"
.IX Item "--help" .Ip "\fB\*(--target-help\fR" 4
.if n .Ip "\f(CW""\-\-target\-help""\fR" 4 .IX Item "target-help"
.el .Ip "\f(CW\-\-target\-help\fR" 4
.IX Item "--target-help"
.PD .PD
Print text describing all the command line options instead of Print text describing all the command line options instead of
preprocessing anything. preprocessing anything.
.if n .Ip "\f(CW""\-v""\fR" 4 .Ip "\fB\-v\fR" 4
.el .Ip "\f(CW\-v\fR" 4
.IX Item "-v" .IX Item "-v"
Verbose mode. Print out \s-1GNU\s0 \s-1CPP\s0's version number at the beginning of Verbose mode. Print out \s-1GNU\s0 \s-1CPP\s0's version number at the beginning of
execution, and report the final form of the include path. execution, and report the final form of the include path.
.if n .Ip "\f(CW""\-H""\fR" 4 .Ip "\fB\-H\fR" 4
.el .Ip "\f(CW\-H\fR" 4
.IX Item "-H" .IX Item "-H"
Print the name of each header file used, in addition to other normal Print the name of each header file used, in addition to other normal
activities. Each name is indented to show how deep in the activities. Each name is indented to show how deep in the
\&\fB#include\fR stack it is. \&\fB#include\fR stack it is.
.if n .Ip "\f(CW""\-version""\fR" 4 .Ip "\fB\-version\fR" 4
.el .Ip "\f(CW\-version\fR" 4
.IX Item "-version" .IX Item "-version"
.PD 0 .PD 0
.if n .Ip "\f(CW""\-\-version""\fR" 4 .Ip "\fB\*(--version\fR" 4
.el .Ip "\f(CW\-\-version\fR" 4 .IX Item "version"
.IX Item "--version"
.PD .PD
Print out \s-1GNU\s0 \s-1CPP\s0's version number. With one dash, proceed to Print out \s-1GNU\s0 \s-1CPP\s0's version number. With one dash, proceed to
preprocess as normal. With two dashes, exit immediately. preprocess as normal. With two dashes, exit immediately.
...@@ -763,7 +695,7 @@ Free Software Foundation, Inc. ...@@ -763,7 +695,7 @@ Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document Permission is granted to copy, distribute and/or modify this document
under the terms of the \s-1GNU\s0 Free Documentation License, Version 1.1 or under the terms of the \s-1GNU\s0 Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation. A copy of any later version published by the Free Software Foundation. A copy of
the license is included in the accompanying manual for \s-1GNU\s0 \s-1CC\s0, in the the license is included in the accompanying manual for \s-1GCC\s0, in the
section ``\s-1GNU\s0 Free Documentation License''. section ``\s-1GNU\s0 Free Documentation License''.
This manual contains no Invariant Sections, and has no Front-Cover Texts This manual contains no Invariant Sections, and has no Front-Cover Texts
or Back-Cover Texts. or Back-Cover Texts.
gcc/doc/cpp.texi
...@@ -15,7 +15,7 @@ Free Software Foundation, Inc. ...@@ -15,7 +15,7 @@ Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation. A copy of any later version published by the Free Software Foundation. A copy of
the license is included in the accompanying manual for GNU CC, in the the license is included in the accompanying manual for GCC, in the
section ``GNU Free Documentation License''. section ``GNU Free Documentation License''.
@c man end @c man end
@end macro @end macro
...@@ -45,17 +45,9 @@ This manual contains no Invariant Sections. The Front-Cover Texts are ...@@ -45,17 +45,9 @@ This manual contains no Invariant Sections. The Front-Cover Texts are
funds for GNU development. funds for GNU development.
@end macro @end macro
@c Better form for references to other manuals. @macro gcctabopt{body}
@ifinfo @code{\body\}
@macro docref{docname}
GNU \docname\. @ref{Top, \docname\, , \docname\}@c
@end macro
@end ifinfo
@ifnotinfo
@macro docref{docname}
GNU \docname\@c
@end macro @end macro
@end ifnotinfo
@ifinfo @ifinfo
@dircategory Programming @dircategory Programming
...@@ -214,7 +206,7 @@ Wherever possible, you should use a preprocessor geared to the language ...@@ -214,7 +206,7 @@ Wherever possible, you should use a preprocessor geared to the language
you are writing in. Modern versions of the GNU assembler have macro you are writing in. Modern versions of the GNU assembler have macro
facilities. Most high level programming languages have their own facilities. Most high level programming languages have their own
conditional compilation and inclusion mechanism. If all else fails, conditional compilation and inclusion mechanism. If all else fails,
try a true general text processor, such as @docref{M4}. try a true general text processor, such as GNU M4.
C preprocessors vary in some details. This manual discusses the GNU C C preprocessors vary in some details. This manual discusses the GNU C
preprocessor, which provides a small superset of the features of ISO preprocessor, which provides a small superset of the features of ISO
...@@ -346,6 +338,7 @@ because they would end in the same place anyway. ...@@ -346,6 +338,7 @@ because they would end in the same place anyway.
// @r{this is} // @r{one comment} // @r{this is} // @r{one comment}
@r{text outside comment} @r{text outside comment}
@end example @end example
@end enumerate
It is safe to put line comments inside block comments, or vice versa. It is safe to put line comments inside block comments, or vice versa.
...@@ -376,7 +369,6 @@ Comments are not recognized within string literals. @t{@w{"/* blah ...@@ -376,7 +369,6 @@ Comments are not recognized within string literals. @t{@w{"/* blah
Line comments are not in the 1989 edition of the C standard, but they Line comments are not in the 1989 edition of the C standard, but they
are recognized by GCC as an extension. In C++ and in the 1999 edition are recognized by GCC as an extension. In C++ and in the 1999 edition
of the C standard, they are an official part of the language. of the C standard, they are an official part of the language.
@end enumerate
Since these transformations happen before all other processing, you can Since these transformations happen before all other processing, you can
split a line mechanically with backslash-newline anywhere. You can split a line mechanically with backslash-newline anywhere. You can
...@@ -398,7 +390,7 @@ O 10\ ...@@ -398,7 +390,7 @@ O 10\
@end example @end example
@noindent @noindent
is equivalent to @samp{@w{#define FOO 1020}}. All these tricks are is equivalent to @code{@w{#define FOO 1020}}. All these tricks are
extremely confusing and should not be used in code intended to be extremely confusing and should not be used in code intended to be
readable. readable.
...@@ -439,13 +431,13 @@ but it is often necessary to avoid ambiguities. ...@@ -439,13 +431,13 @@ but it is often necessary to avoid ambiguities.
When faced with a sequence of characters that has more than one possible When faced with a sequence of characters that has more than one possible
tokenization, the preprocessor is greedy. It always makes each token, tokenization, the preprocessor is greedy. It always makes each token,
starting from the left, as big as possible before moving on to the next starting from the left, as big as possible before moving on to the next
token. For instance, @samp{a+++++b} is interpreted as token. For instance, @code{a+++++b} is interpreted as
@samp{@w{a ++ ++ + b}}, not as @samp{@w{a ++ + ++ b}}, even though the @code{@w{a ++ ++ + b}}, not as @code{@w{a ++ + ++ b}}, even though the
latter tokenization could be part of a valid C program and the former latter tokenization could be part of a valid C program and the former
could not. could not.
Once the input file is broken into tokens, the token boundaries never Once the input file is broken into tokens, the token boundaries never
change, except when the @samp{##} preprocessing operator is used to glue change, except when the @samp{##} preprocessing operator is used to paste
tokens together. @xref{Concatenation}. For example, tokens together. @xref{Concatenation}. For example,
@example @example
...@@ -469,7 +461,7 @@ letters, digits, or underscores, which begins with a letter or ...@@ -469,7 +461,7 @@ letters, digits, or underscores, which begins with a letter or
underscore. Keywords of C have no significance to the preprocessor; underscore. Keywords of C have no significance to the preprocessor;
they are ordinary identifiers. You can define a macro whose name is a they are ordinary identifiers. You can define a macro whose name is a
keyword, for instance. The only identifier which can be considered a keyword, for instance. The only identifier which can be considered a
preprocessing keyword is @samp{defined}. @xref{Defined}. preprocessing keyword is @code{defined}. @xref{Defined}.
This is mostly true of other languages which use the C preprocessor. This is mostly true of other languages which use the C preprocessor.
However, a few of the keywords of C++ are significant even in the However, a few of the keywords of C++ are significant even in the
...@@ -479,9 +471,15 @@ In the 1999 C standard, identifiers may contain letters which are not ...@@ -479,9 +471,15 @@ In the 1999 C standard, identifiers may contain letters which are not
part of the ``basic source character set,'' at the implementation's part of the ``basic source character set,'' at the implementation's
discretion (such as accented Latin letters, Greek letters, or Chinese discretion (such as accented Latin letters, Greek letters, or Chinese
ideograms). This may be done with an extended character set, or the ideograms). This may be done with an extended character set, or the
@samp{\u} and @samp{\U} escape sequences. GNU C does not presently @samp{\u} and @samp{\U} escape sequences. GCC does not presently
implement either feature in the preprocessor or the compiler. implement either feature in the preprocessor or the compiler.
As an extension, GCC treats @samp{$} as a letter. This is for
compatibility with some systems, such as VMS, where @samp{$} is commonly
used in system-defined function and object names. @samp{$} is not a
letter in strictly conforming mode, or if you specify the @option{-$}
option. @xref{Invocation}.
@cindex numbers @cindex numbers
@cindex preprocessing numbers @cindex preprocessing numbers
A @dfn{preprocessing number} has a rather bizarre definition. The A @dfn{preprocessing number} has a rather bizarre definition. The
...@@ -500,12 +498,12 @@ from the full complexity of numeric constants. It does not have to ...@@ -500,12 +498,12 @@ from the full complexity of numeric constants. It does not have to
distinguish between lexically valid and invalid floating-point numbers, distinguish between lexically valid and invalid floating-point numbers,
which is complicated. The definition also permits you to split an which is complicated. The definition also permits you to split an
identifier at any position and get exactly two tokens, which can then be identifier at any position and get exactly two tokens, which can then be
glued back together with the @samp{##} operator. pasted back together with the @samp{##} operator.
It's possible for preprocessing numbers to cause programs to be It's possible for preprocessing numbers to cause programs to be
misinterpreted. For example, @samp{0xE+12} is a preprocessing number misinterpreted. For example, @code{0xE+12} is a preprocessing number
which does not translate to any valid numeric constant, therefore a which does not translate to any valid numeric constant, therefore a
syntax error. It does not mean @samp{@w{0xE + 12}}, which is what you syntax error. It does not mean @code{@w{0xE + 12}}, which is what you
might have intended. might have intended.
@cindex string literals @cindex string literals
...@@ -517,15 +515,15 @@ might have intended. ...@@ -517,15 +515,15 @@ might have intended.
header file names (the argument of @samp{#include}).@footnote{The C header file names (the argument of @samp{#include}).@footnote{The C
standard uses the term @dfn{string literal} to refer only to what we are standard uses the term @dfn{string literal} to refer only to what we are
calling @dfn{string constants}.} String constants and character calling @dfn{string constants}.} String constants and character
constants are straightforward: @t{"..."} or @t{'...'}. In either case constants are straightforward: @t{"@dots{}"} or @t{'@dots{}'}. In
the closing quote may be escaped with a backslash: @t{'\'@:'} is the either case the closing quote may be escaped with a backslash:
character constant for @samp{'}. There is no limit on the length of a @t{'\'@:'} is the character constant for @samp{'}. There is no limit on
character constant, but the value of a character constant that contains the length of a character constant, but the value of a character
more than one character is implementation-defined. @xref{Implementation constant that contains more than one character is
Details}. implementation-defined. @xref{Implementation Details}.
Header file names either look like string constants, @t{"..."}, or are Header file names either look like string constants, @t{"@dots{}"}, or are
written with angle brackets instead, @t{<...>}. In either case, written with angle brackets instead, @t{<@dots{}>}. In either case,
backslash is an ordinary character. There is no way to escape the backslash is an ordinary character. There is no way to escape the
closing quote or angle bracket. The preprocessor looks for the header closing quote or angle bracket. The preprocessor looks for the header
file in different places depending on which form you use. @xref{Include file in different places depending on which form you use. @xref{Include
...@@ -558,8 +556,9 @@ Any other single character is considered ``other.'' It is passed on to ...@@ -558,8 +556,9 @@ Any other single character is considered ``other.'' It is passed on to
the preprocessor's output unmolested. The C compiler will almost the preprocessor's output unmolested. The C compiler will almost
certainly reject source code containing ``other'' tokens. In ASCII, the certainly reject source code containing ``other'' tokens. In ASCII, the
only other characters are @samp{@@}, @samp{$}, @samp{`}, and control only other characters are @samp{@@}, @samp{$}, @samp{`}, and control
characters other than NUL (all bits zero). All characters with the high characters other than NUL (all bits zero). (Note that @samp{$} is
bit set (numeric range 0x7F--0xFF) are also ``other'' in the present normally considered a letter.) All characters with the high bit set
(numeric range 0x7F--0xFF) are also ``other'' in the present
implementation. This will change when proper support for international implementation. This will change when proper support for international
character sets is added to GCC. character sets is added to GCC.
...@@ -635,7 +634,7 @@ the directive that defines a macro. ...@@ -635,7 +634,7 @@ the directive that defines a macro.
The @samp{#} which begins a directive cannot come from a macro The @samp{#} which begins a directive cannot come from a macro
expansion. Also, the directive name is not macro expanded. Thus, if expansion. Also, the directive name is not macro expanded. Thus, if
@samp{foo} is defined as a macro expanding to @samp{define}, that does @code{foo} is defined as a macro expanding to @code{define}, that does
not make @samp{#foo} a valid preprocessing directive. not make @samp{#foo} a valid preprocessing directive.
The set of valid directive names is fixed. Programs cannot define new The set of valid directive names is fixed. Programs cannot define new
...@@ -723,13 +722,13 @@ current file, then in the same directories used for @code{<@var{file}>}. ...@@ -723,13 +722,13 @@ current file, then in the same directories used for @code{<@var{file}>}.
The argument of @samp{#include}, whether delimited with quote marks or The argument of @samp{#include}, whether delimited with quote marks or
angle brackets, behaves like a string constant in that comments are not angle brackets, behaves like a string constant in that comments are not
recognized, and macro names are not expanded. Thus, @samp{@w{#include recognized, and macro names are not expanded. Thus, @code{@w{#include
<x/*y>}} specifies inclusion of a system header file named @file{x/*y}. <x/*y>}} specifies inclusion of a system header file named @file{x/*y}.
However, if backslashes occur within @var{file}, they are considered However, if backslashes occur within @var{file}, they are considered
ordinary text characters, not escape characters. None of the character ordinary text characters, not escape characters. None of the character
escape sequences appropriate to string constants in C are processed. escape sequences appropriate to string constants in C are processed.
Thus, @samp{@w{#include "x\n\\y"}} specifies a filename containing three Thus, @code{@w{#include "x\n\\y"}} specifies a filename containing three
backslashes. (Some systems interpret @samp{\} as a pathname separator. backslashes. (Some systems interpret @samp{\} as a pathname separator.
All of these also interpret @samp{/} the same way. It is most portable All of these also interpret @samp{/} the same way. It is most portable
to use only @samp{/}.) to use only @samp{/}.)
...@@ -793,7 +792,7 @@ comment, string constant or character constant in an included file is ...@@ -793,7 +792,7 @@ comment, string constant or character constant in an included file is
considered to end (with an error message) at the end of the file. considered to end (with an error message) at the end of the file.
To avoid confusion, it is best if header files contain only complete To avoid confusion, it is best if header files contain only complete
syntactic units --- function declarations or definitions, type syntactic units---function declarations or definitions, type
declarations, etc. declarations, etc.
The line following the @samp{#include} directive is always treated as a The line following the @samp{#include} directive is always treated as a
...@@ -805,7 +804,7 @@ final newline. ...@@ -805,7 +804,7 @@ final newline.
GCC looks in several different places for headers. On a normal Unix GCC looks in several different places for headers. On a normal Unix
system, if you do not instruct it otherwise, it will look for headers system, if you do not instruct it otherwise, it will look for headers
requested with @samp{@w{#include <@var{file}>}} in: requested with @code{@w{#include <@var{file}>}} in:
@example @example
/usr/local/include /usr/local/include
...@@ -814,7 +813,7 @@ requested with @samp{@w{#include <@var{file}>}} in: ...@@ -814,7 +813,7 @@ requested with @samp{@w{#include <@var{file}>}} in:
/usr/include /usr/include
@end example @end example
For C++ programs, it will also look in @samp{/usr/include/g++-v3}, For C++ programs, it will also look in @file{/usr/include/g++-v3},
first. In the above, @var{target} is the canonical name of the system first. In the above, @var{target} is the canonical name of the system
GCC was configured to compile code for; often but not always the same as GCC was configured to compile code for; often but not always the same as
the canonical name of the system it runs on. @var{version} is the the canonical name of the system it runs on. @var{version} is the
...@@ -828,11 +827,11 @@ also prevent GCC from searching any of the default directories with the ...@@ -828,11 +827,11 @@ also prevent GCC from searching any of the default directories with the
operating system kernel or some other program that does not use the operating system kernel or some other program that does not use the
standard C library facilities, or the standard C library itself. standard C library facilities, or the standard C library itself.
GCC looks for headers requested with @samp{@w{#include "@var{file}"}} GCC looks for headers requested with @code{@w{#include "@var{file}"}}
first in the directory containing the current file, then in the same first in the directory containing the current file, then in the same
places it would have looked for a header requested with angle brackets. places it would have looked for a header requested with angle brackets.
For example, if @file{/usr/include/sys/stat.h} contains For example, if @file{/usr/include/sys/stat.h} contains
@samp{@w{#include "types.h"}}, GCC looks for @file{types.h} first in @code{@w{#include "types.h"}}, GCC looks for @file{types.h} first in
@file{/usr/include/sys}, then in its usual search path. @file{/usr/include/sys}, then in its usual search path.
@samp{#line} (@pxref{Line Control}) does not change GCC's idea of the @samp{#line} (@pxref{Line Control}) does not change GCC's idea of the
...@@ -938,9 +937,10 @@ argument of @samp{#include}, you simply put a macro name there instead: ...@@ -938,9 +937,10 @@ argument of @samp{#include}, you simply put a macro name there instead:
#include SYSTEM_H #include SYSTEM_H
@end example @end example
@samp{SYSTEM_H} will be expanded, and the preprocessor will look for @noindent
@code{SYSTEM_H} will be expanded, and the preprocessor will look for
@file{system_1.h} as if the @samp{#include} had been written that way @file{system_1.h} as if the @samp{#include} had been written that way
originally. @samp{SYSTEM_H} could be defined by your Makefile with a originally. @code{SYSTEM_H} could be defined by your Makefile with a
@option{-D} option. @option{-D} option.
You must be careful when you define the macro. @samp{#define} saves You must be careful when you define the macro. @samp{#define} saves
...@@ -965,6 +965,7 @@ escapes in the string. Therefore ...@@ -965,6 +965,7 @@ escapes in the string. Therefore
#include HEADER #include HEADER
@end example @end example
@noindent
looks for a file named @file{a\"b}. CPP searches for the file according looks for a file named @file{a\"b}. CPP searches for the file according
to the rules for double-quoted includes. to the rules for double-quoted includes.
...@@ -994,7 +995,7 @@ minimize confusion of people reading your program. ...@@ -994,7 +995,7 @@ minimize confusion of people reading your program.
@findex #include_next @findex #include_next
Sometimes it is necessary to adjust the contents of a system-provided Sometimes it is necessary to adjust the contents of a system-provided
header file without editing it directly. GCC's @samp{fixincludes} header file without editing it directly. GCC's @command{fixincludes}
operation does this, for example. One way to do that would be to create operation does this, for example. One way to do that would be to create
a new header file with the same name and insert it in the search path a new header file with the same name and insert it in the search path
before the original header. That works fine as long as you're willing before the original header. That works fine as long as you're willing
...@@ -1023,13 +1024,13 @@ in which the current file was found. ...@@ -1023,13 +1024,13 @@ in which the current file was found.
Suppose you specify @option{-I /usr/local/include}, and the list of Suppose you specify @option{-I /usr/local/include}, and the list of
directories to search also includes @file{/usr/include}; and suppose directories to search also includes @file{/usr/include}; and suppose
both directories contain @file{signal.h}. Ordinary @samp{#include both directories contain @file{signal.h}. Ordinary @code{@w{#include
<signal.h>} finds the file under @file{/usr/local/include}. If that <signal.h>}} finds the file under @file{/usr/local/include}. If that
file contains @samp{#include_next <signal.h>}, it starts searching file contains @code{@w{#include_next <signal.h>}}, it starts searching
after that directory, and finds the file in @file{/usr/include}. after that directory, and finds the file in @file{/usr/include}.
@samp{#include_next} does not distinguish between @samp{<@var{file}>} @samp{#include_next} does not distinguish between @code{<@var{file}>}
and @samp{"@var{file}"} inclusion, nor does it check that the file you and @code{"@var{file}"} inclusion, nor does it check that the file you
specify has the same name as the current file. It simply looks for the specify has the same name as the current file. It simply looks for the
file named, starting with the directory in the search path after the one file named, starting with the directory in the search path after the one
where the current file was found. where the current file was found.
...@@ -1038,7 +1039,7 @@ The use of @samp{#include_next} can lead to great confusion. We ...@@ -1038,7 +1039,7 @@ The use of @samp{#include_next} can lead to great confusion. We
recommend it be used only when there is no other alternative. In recommend it be used only when there is no other alternative. In
particular, it should not be used in the headers belonging to a particular, it should not be used in the headers belonging to a
specific program, only to make global corrections along the lines specific program, only to make global corrections along the lines
of @samp{fixincludes}. of @command{fixincludes}.
@node System Headers @node System Headers
@section System Headers @section System Headers
...@@ -1046,7 +1047,7 @@ of @samp{fixincludes}. ...@@ -1046,7 +1047,7 @@ of @samp{fixincludes}.
The header files declaring interfaces to the operating system and The header files declaring interfaces to the operating system and
runtime libraries often cannot be written in strictly conforming C@. runtime libraries often cannot be written in strictly conforming C@.
Therefore, GNU C gives code found in @dfn{system headers} special Therefore, GCC gives code found in @dfn{system headers} special
treatment. All warnings, other than those generated by @samp{#warning} treatment. All warnings, other than those generated by @samp{#warning}
(@pxref{Diagnostics}), are suppressed while GCC is processing a system (@pxref{Diagnostics}), are suppressed while GCC is processing a system
header. Macros defined in a system header are immune to a few warnings header. Macros defined in a system header are immune to a few warnings
...@@ -1071,10 +1072,10 @@ command line. If the same directory is named by both @option{-I} and ...@@ -1071,10 +1072,10 @@ command line. If the same directory is named by both @option{-I} and
had never been specified at all. had never been specified at all.
@findex #pragma GCC system_header @findex #pragma GCC system_header
There is also a directive, @samp{@w{#pragma GCC system_header}}, which There is also a directive, @code{@w{#pragma GCC system_header}}, which
tells GCC to consider the rest of the current include file a system tells GCC to consider the rest of the current include file a system
header, no matter where it was found. Code that comes before the header, no matter where it was found. Code that comes before the
@samp{#pragma} in the file will not be affected. @samp{@w{#pragma GCC @samp{#pragma} in the file will not be affected. @code{@w{#pragma GCC
system_header}} has no effect in the primary source file. system_header}} has no effect in the primary source file.
On very old systems, some of the pre-defined system header directories On very old systems, some of the pre-defined system header directories
...@@ -1094,9 +1095,9 @@ when used, @dfn{function-like} macros resemble function calls. ...@@ -1094,9 +1095,9 @@ when used, @dfn{function-like} macros resemble function calls.
You may define any valid identifier as a macro, even if it is a C You may define any valid identifier as a macro, even if it is a C
keyword. The preprocessor does not know anything about keywords. This keyword. The preprocessor does not know anything about keywords. This
can be useful if you wish to hide a keyword such as @samp{const} from an can be useful if you wish to hide a keyword such as @code{const} from an
older compiler that does not understand it. However, the preprocessor older compiler that does not understand it. However, the preprocessor
operator @samp{defined} (@pxref{Defined}) can never be defined as a operator @code{defined} (@pxref{Defined}) can never be defined as a
macro, and C++'s named operators (@pxref{C++ Named Operators}) cannot be macro, and C++'s named operators (@pxref{C++ Named Operators}) cannot be
macros when you are compiling C++. macros when you are compiling C++.
...@@ -1134,8 +1135,8 @@ be an abbreviation for, which is variously referred to as the macro's ...@@ -1134,8 +1135,8 @@ be an abbreviation for, which is variously referred to as the macro's
@end example @end example
@noindent @noindent
defines a macro named @samp{BUFFER_SIZE} as an abbreviation for the defines a macro named @code{BUFFER_SIZE} as an abbreviation for the
token @samp{1024}. If somewhere after this @samp{#define} directive token @code{1024}. If somewhere after this @samp{#define} directive
there comes a C statement of the form there comes a C statement of the form
@example @example
...@@ -1144,7 +1145,7 @@ foo = (char *) malloc (BUFFER_SIZE); ...@@ -1144,7 +1145,7 @@ foo = (char *) malloc (BUFFER_SIZE);
@noindent @noindent
then the C preprocessor will recognize and @dfn{expand} the macro then the C preprocessor will recognize and @dfn{expand} the macro
@samp{BUFFER_SIZE}. The C compiler will see the same tokens as it would @code{BUFFER_SIZE}. The C compiler will see the same tokens as it would
if you had written if you had written
@example @example
...@@ -1210,19 +1211,19 @@ TABLESIZE ...@@ -1210,19 +1211,19 @@ TABLESIZE
@end example @end example
@noindent @noindent
@samp{TABLESIZE} is expanded first to produce @samp{BUFSIZE}, then that @code{TABLESIZE} is expanded first to produce @code{BUFSIZE}, then that
macro is expanded to produce the final result, @samp{1024}. macro is expanded to produce the final result, @code{1024}.
Notice that @samp{BUFSIZE} was not defined when @samp{TABLESIZE} was Notice that @code{BUFSIZE} was not defined when @code{TABLESIZE} was
defined. The @samp{#define} for @samp{TABLESIZE} uses exactly the defined. The @samp{#define} for @code{TABLESIZE} uses exactly the
expansion you specify --- in this case, @samp{BUFSIZE} --- and does not expansion you specify---in this case, @code{BUFSIZE}---and does not
check to see whether it too contains macro names. Only when you check to see whether it too contains macro names. Only when you
@emph{use} @samp{TABLESIZE} is the result of its expansion scanned for @emph{use} @code{TABLESIZE} is the result of its expansion scanned for
more macro names. more macro names.
This makes a difference if you change the definition of @samp{BUFSIZE} This makes a difference if you change the definition of @code{BUFSIZE}
at some point in the source file. @samp{TABLESIZE}, defined as shown, at some point in the source file. @code{TABLESIZE}, defined as shown,
will always expand using the definition of @samp{BUFSIZE} that is will always expand using the definition of @code{BUFSIZE} that is
currently in effect: currently in effect:
@example @example
...@@ -1233,7 +1234,7 @@ currently in effect: ...@@ -1233,7 +1234,7 @@ currently in effect:
@end example @end example
@noindent @noindent
Now @samp{TABLESIZE} expands (in two stages) to @samp{37}. Now @code{TABLESIZE} expands (in two stages) to @code{37}.
If the expansion of a macro contains its own name, either directly or If the expansion of a macro contains its own name, either directly or
via intermediate macros, it is not expanded again when the expansion is via intermediate macros, it is not expanded again when the expansion is
...@@ -1268,7 +1269,7 @@ extern void foo(void); ...@@ -1268,7 +1269,7 @@ extern void foo(void);
funcptr = foo; funcptr = foo;
@end example @end example
Here the call to @samp{foo()} will use the macro, but the function Here the call to @code{foo()} will use the macro, but the function
pointer will get the address of the real function. If the macro were to pointer will get the address of the real function. If the macro were to
be expanded, it would cause a syntax error. be expanded, it would cause a syntax error.
...@@ -1285,7 +1286,7 @@ lang_init() ...@@ -1285,7 +1286,7 @@ lang_init()
The first two pairs of parentheses in this expansion come from the The first two pairs of parentheses in this expansion come from the
macro. The third is the pair that was originally after the macro macro. The third is the pair that was originally after the macro
invocation. Since @samp{lang_init} is an object-like macro, it does not invocation. Since @code{lang_init} is an object-like macro, it does not
consume those parentheses. consume those parentheses.
@node Macro Arguments @node Macro Arguments
...@@ -1303,7 +1304,7 @@ separated by commas and optionally whitespace. ...@@ -1303,7 +1304,7 @@ separated by commas and optionally whitespace.
To invoke a macro that takes arguments, you write the name of the macro To invoke a macro that takes arguments, you write the name of the macro
followed by a list of @dfn{actual arguments} in parentheses, separated followed by a list of @dfn{actual arguments} in parentheses, separated
by commas. The invocation of the macro need not be restricted to a by commas. The invocation of the macro need not be restricted to a
single logical line - it can cross as many lines in the source file as single logical line---it can cross as many lines in the source file as
you wish. The number of arguments you give must match the number of you wish. The number of arguments you give must match the number of
parameters in the macro definition. When the macro is expanded, each parameters in the macro definition. When the macro is expanded, each
use of a parameter in its body is replaced by the tokens of the use of a parameter in its body is replaced by the tokens of the
...@@ -1336,9 +1337,9 @@ macro (array[x = y, x + 1]) ...@@ -1336,9 +1337,9 @@ macro (array[x = y, x + 1])
@end example @end example
@noindent @noindent
passes two arguments to @code{macro}: @samp{array[x = y} and @samp{x + passes two arguments to @code{macro}: @code{array[x = y} and @code{x +
1]}. If you want to supply @samp{array[x = y, x + 1]} as an argument, 1]}. If you want to supply @code{array[x = y, x + 1]} as an argument,
you can write it as @samp{array[(x = y, x + 1)]}, which is equivalent C you can write it as @code{array[(x = y, x + 1)]}, which is equivalent C
code. code.
All arguments to a macro are completely macro-expanded before they are All arguments to a macro are completely macro-expanded before they are
...@@ -1349,7 +1350,7 @@ about whether any function call is actually a macro invocation. You can ...@@ -1349,7 +1350,7 @@ about whether any function call is actually a macro invocation. You can
run into trouble if you try to be too clever, though. @xref{Argument run into trouble if you try to be too clever, though. @xref{Argument
Prescan}, for detailed discussion. Prescan}, for detailed discussion.
For example, @samp{min (min (a, b), c)} is first expanded to For example, @code{min (min (a, b), c)} is first expanded to
@example @example
min (((a) < (b) ? (a) : (b)), (c)) min (((a) < (b) ? (a) : (b)), (c))
...@@ -1374,7 +1375,7 @@ You can leave macro arguments empty; this is not an error for the ...@@ -1374,7 +1375,7 @@ You can leave macro arguments empty; this is not an error for the
preprocessor (but many macros will then expand to invalid code). preprocessor (but many macros will then expand to invalid code).
You cannot leave out arguments entirely; if a macro takes two arguments, You cannot leave out arguments entirely; if a macro takes two arguments,
there must be exactly one comma at the top level of its argument list. there must be exactly one comma at the top level of its argument list.
Here are some silly examples using @samp{min}: Here are some silly examples using @code{min}:
@example @example
min(, b) @expansion{} (( ) < (b) ? ( ) : (b)) min(, b) @expansion{} (( ) < (b) ? ( ) : (b))
...@@ -1387,7 +1388,7 @@ min(,,) @error{} macro "min" passed 3 arguments, but takes just 2 ...@@ -1387,7 +1388,7 @@ min(,,) @error{} macro "min" passed 3 arguments, but takes just 2
@end example @end example
Whitespace is not a preprocessing token, so if a macro @code{foo} takes Whitespace is not a preprocessing token, so if a macro @code{foo} takes
one argument, @samp{@w{foo ()}} and @samp{@w{foo ( )}} both supply it an one argument, @code{@w{foo ()}} and @code{@w{foo ( )}} both supply it an
empty argument. Previous GNU preprocessor implementations and empty argument. Previous GNU preprocessor implementations and
documentation were incorrect on this point, insisting that a documentation were incorrect on this point, insisting that a
function-like macro that takes a single argument be passed a space if an function-like macro that takes a single argument be passed a space if an
...@@ -1436,21 +1437,21 @@ WARN_IF (x == 0); ...@@ -1436,21 +1437,21 @@ WARN_IF (x == 0);
@end example @end example
@noindent @noindent
The argument for @samp{EXP} is substituted once, as-is, into the The argument for @code{EXP} is substituted once, as-is, into the
@samp{if} statement, and once, stringified, into the argument to @code{if} statement, and once, stringified, into the argument to
@samp{fprintf}. If @samp{x} were a macro, it would be expanded in the @code{fprintf}. If @code{x} were a macro, it would be expanded in the
@samp{if} statement, but not in the string. @code{if} statement, but not in the string.
The @samp{do} and @samp{while (0)} are a kludge to make it possible to The @code{do} and @code{while (0)} are a kludge to make it possible to
write @samp{WARN_IF (@var{arg});}, which the resemblance of write @code{WARN_IF (@var{arg});}, which the resemblance of
@samp{WARN_IF} to a function would make C programmers want to do; see @code{WARN_IF} to a function would make C programmers want to do; see
@ref{Swallowing the Semicolon}. @ref{Swallowing the Semicolon}.
Stringification in C involves more than putting double-quote characters Stringification in C involves more than putting double-quote characters
around the fragment. The preprocessor backslash-escapes the surrounding around the fragment. The preprocessor backslash-escapes the surrounding
quotes of string literals, and all backslashes within string and quotes of string literals, and all backslashes within string and
character constants, in order to get a valid C string constant with the character constants, in order to get a valid C string constant with the
proper contents. Thus, stringifying @samp{@w{p = "foo\n";}} results in proper contents. Thus, stringifying @code{@w{p = "foo\n";}} results in
@t{@w{"p = \"foo\\n\";"}}. However, backslashes that are not inside string @t{@w{"p = \"foo\\n\";"}}. However, backslashes that are not inside string
or character constants are not duplicated: @samp{\n} by itself or character constants are not duplicated: @samp{\n} by itself
stringifies to @t{"\n"}. stringifies to @t{"\n"}.
...@@ -1500,13 +1501,13 @@ the two original tokens in the macro expansion. Usually both will be ...@@ -1500,13 +1501,13 @@ the two original tokens in the macro expansion. Usually both will be
identifiers, or one will be an identifier and the other a preprocessing identifiers, or one will be an identifier and the other a preprocessing
number. When pasted, they make a longer identifier. This isn't the number. When pasted, they make a longer identifier. This isn't the
only valid case. It is also possible to concatenate two numbers (or a only valid case. It is also possible to concatenate two numbers (or a
number and a name, such as @samp{1.5} and @samp{e3}) into a number. number and a name, such as @code{1.5} and @code{e3}) into a number.
Also, multi-character operators such as @samp{+=} can be formed by Also, multi-character operators such as @code{+=} can be formed by
token pasting. token pasting.
However, two tokens that don't together form a valid token cannot be However, two tokens that don't together form a valid token cannot be
pasted together. For example, you cannot concatenate @samp{x} with pasted together. For example, you cannot concatenate @code{x} with
@samp{+} in either order. If you try, the preprocessor issues a warning @code{+} in either order. If you try, the preprocessor issues a warning
and emits the two tokens as if they had been written next to each other. and emits the two tokens as if they had been written next to each other.
It is common to find unnecessary uses of @samp{##} in complex macros. It is common to find unnecessary uses of @samp{##} in complex macros.
If you get this warning, it is likely that you can simply remove the If you get this warning, it is likely that you can simply remove the
...@@ -1580,7 +1581,7 @@ a function can. The syntax for defining the macro is similar to that of ...@@ -1580,7 +1581,7 @@ a function can. The syntax for defining the macro is similar to that of
a function. Here is an example: a function. Here is an example:
@example @example
#define eprintf(...) fprintf (stderr, __VA_ARGS__) #define eprintf(@dots{}) fprintf (stderr, __VA_ARGS__)
@end example @end example
This kind of macro is called @dfn{variadic}. When the macro is invoked, This kind of macro is called @dfn{variadic}. When the macro is invoked,
...@@ -1608,7 +1609,7 @@ before the @samp{@dots{}}; that name is used for the variable argument. ...@@ -1608,7 +1609,7 @@ before the @samp{@dots{}}; that name is used for the variable argument.
The @code{eprintf} macro above could be written The @code{eprintf} macro above could be written
@example @example
#define eprintf(args...) fprintf (stderr, args) #define eprintf(args@dots{}) fprintf (stderr, args)
@end example @end example
@noindent @noindent
...@@ -1619,9 +1620,10 @@ You can have named arguments as well as variable arguments in a variadic ...@@ -1619,9 +1620,10 @@ You can have named arguments as well as variable arguments in a variadic
macro. We could define @code{eprintf} like this, instead: macro. We could define @code{eprintf} like this, instead:
@example @example
#define eprintf(format, ...) fprintf (stderr, format, __VA_ARGS__) #define eprintf(format, @dots{}) fprintf (stderr, format, __VA_ARGS__)
@end example @end example
@noindent
This formulation looks more descriptive, but unfortunately it is less This formulation looks more descriptive, but unfortunately it is less
flexible: you must now supply at least one argument after the format flexible: you must now supply at least one argument after the format
string. In standard C, you cannot omit the comma separating the named string. In standard C, you cannot omit the comma separating the named
...@@ -1642,14 +1644,16 @@ eprintf ("success!\n") ...@@ -1642,14 +1644,16 @@ eprintf ("success!\n")
@expansion{} fprintf(stderr, "success!\n", ); @expansion{} fprintf(stderr, "success!\n", );
@end example @end example
@noindent
Second, the @samp{##} token paste operator has a special meaning when Second, the @samp{##} token paste operator has a special meaning when
placed between a comma and a variable argument. If you write placed between a comma and a variable argument. If you write
@example @example
#define eprintf(format, ...) fprintf (stderr, format, ##__VA_ARGS__) #define eprintf(format, @dots{}) fprintf (stderr, format, ##__VA_ARGS__)
@end example @end example
and the variable argument is left out when the @samp{eprintf} macro is @noindent
and the variable argument is left out when the @code{eprintf} macro is
used, then the comma before the @samp{##} will be deleted. This does used, then the comma before the @samp{##} will be deleted. This does
@emph{not} happen if you pass an empty argument, nor does it happen if @emph{not} happen if you pass an empty argument, nor does it happen if
the token preceding @samp{##} is anything other than a comma. the token preceding @samp{##} is anything other than a comma.
...@@ -1668,7 +1672,7 @@ purpose. ...@@ -1668,7 +1672,7 @@ purpose.
Variadic macros are a new feature in C99. GNU CPP has supported them Variadic macros are a new feature in C99. GNU CPP has supported them
for a long time, but only with a named variable argument for a long time, but only with a named variable argument
(@samp{args...}, not @samp{...} and @code{@w{__VA_ARGS__}}). If you are (@samp{args@dots{}}, not @samp{@dots{}} and @code{@w{__VA_ARGS__}}). If you are
concerned with portability to previous versions of GCC, you should use concerned with portability to previous versions of GCC, you should use
only named variable arguments. On the other hand, if you are concerned only named variable arguments. On the other hand, if you are concerned
with portability to other conforming implementations of C99, you should with portability to other conforming implementations of C99, you should
...@@ -1682,7 +1686,7 @@ be a comma, and there must be white space between that comma and ...@@ -1682,7 +1686,7 @@ be a comma, and there must be white space between that comma and
whatever comes immediately before it: whatever comes immediately before it:
@example @example
#define eprintf(format, args...) fprintf (stderr, format , ##args) #define eprintf(format, args@dots{}) fprintf (stderr, format , ##args)
@end example @end example
@noindent @noindent
...@@ -1721,7 +1725,7 @@ This macro expands to the name of the current input file, in the form of ...@@ -1721,7 +1725,7 @@ This macro expands to the name of the current input file, in the form of
a C string constant. This is the path by which the preprocessor opened a C string constant. This is the path by which the preprocessor opened
the file, not the short name specified in @samp{#include} or as the the file, not the short name specified in @samp{#include} or as the
input file name argument. For example, input file name argument. For example,
@samp{"/usr/local/include/myheader.h"} is a possible expansion of this @code{"/usr/local/include/myheader.h"} is a possible expansion of this
macro. macro.
@item __LINE__ @item __LINE__
...@@ -1731,7 +1735,7 @@ a pretty strange macro, since its ``definition'' changes with each ...@@ -1731,7 +1735,7 @@ a pretty strange macro, since its ``definition'' changes with each
new line of source code. new line of source code.
@end table @end table
@samp{__FILE__} and @samp{__LINE__} are useful in generating an error @code{__FILE__} and @code{__LINE__} are useful in generating an error
message to report an inconsistency detected by the program; the message message to report an inconsistency detected by the program; the message
can state the source line at which the inconsistency was detected. For can state the source line at which the inconsistency was detected. For
example, example,
...@@ -1743,41 +1747,41 @@ fprintf (stderr, "Internal error: " ...@@ -1743,41 +1747,41 @@ fprintf (stderr, "Internal error: "
length, __FILE__, __LINE__); length, __FILE__, __LINE__);
@end example @end example
An @samp{#include} directive changes the expansions of @samp{__FILE__} An @samp{#include} directive changes the expansions of @code{__FILE__}
and @samp{__LINE__} to correspond to the included file. At the end of and @code{__LINE__} to correspond to the included file. At the end of
that file, when processing resumes on the input file that contained that file, when processing resumes on the input file that contained
the @samp{#include} directive, the expansions of @samp{__FILE__} and the @samp{#include} directive, the expansions of @code{__FILE__} and
@samp{__LINE__} revert to the values they had before the @code{__LINE__} revert to the values they had before the
@samp{#include} (but @samp{__LINE__} is then incremented by one as @samp{#include} (but @code{__LINE__} is then incremented by one as
processing moves to the line after the @samp{#include}). processing moves to the line after the @samp{#include}).
A @samp{#line} directive changes @samp{__LINE__}, and may change A @samp{#line} directive changes @code{__LINE__}, and may change
@samp{__FILE__} as well. @xref{Line Control}. @code{__FILE__} as well. @xref{Line Control}.
C99 introduces @samp{__func__}, and GCC has provided @samp{__FUNCTION__} C99 introduces @code{__func__}, and GCC has provided @code{__FUNCTION__}
for a long time. Both of these are strings containing the name of the for a long time. Both of these are strings containing the name of the
current function (there are slight semantic differences; see the GCC current function (there are slight semantic differences; see the GCC
manual). Neither of them is a macro; the preprocessor does not know the manual). Neither of them is a macro; the preprocessor does not know the
name of the current function. They tend to be useful in conjunction name of the current function. They tend to be useful in conjunction
with @samp{__FILE__} and @samp{__LINE__}, though. with @code{__FILE__} and @code{__LINE__}, though.
@table @code @table @code
@item __DATE__ @item __DATE__
This macro expands to a string constant that describes the date on which This macro expands to a string constant that describes the date on which
the preprocessor is being run. The string constant contains eleven the preprocessor is being run. The string constant contains eleven
characters and looks like @w{@samp{"Feb 12 1996"}}. If the day of the characters and looks like @code{@w{"Feb 12 1996"}}. If the day of the
month is less than 10, it is padded with a space on the left. month is less than 10, it is padded with a space on the left.
@item __TIME__ @item __TIME__
This macro expands to a string constant that describes the time at This macro expands to a string constant that describes the time at
which the preprocessor is being run. The string constant contains which the preprocessor is being run. The string constant contains
eight characters and looks like @samp{"23:59:01"}. eight characters and looks like @code{"23:59:01"}.
@item __STDC__ @item __STDC__
In normal operation, this macro expands to the constant 1, to signify In normal operation, this macro expands to the constant 1, to signify
that this compiler conforms to ISO Standard C@. If GNU CPP is used with that this compiler conforms to ISO Standard C@. If GNU CPP is used with
a compiler other than GNU CC, this is not necessarily true; however, the a compiler other than GCC, this is not necessarily true; however, the
preprocessor always conforms to the standard, unless the preprocessor always conforms to the standard, unless the
@option{-traditional} option is used. @option{-traditional} option is used.
...@@ -1795,14 +1799,14 @@ cancel treatment of those headers as system headers. @xref{Invocation}. ...@@ -1795,14 +1799,14 @@ cancel treatment of those headers as system headers. @xref{Invocation}.
@item __STDC_VERSION__ @item __STDC_VERSION__
This macro expands to the C Standard's version number, a long integer This macro expands to the C Standard's version number, a long integer
constant of the form @samp{@var{yyyy}@var{mm}L} where @var{yyyy} and constant of the form @code{@var{yyyy}@var{mm}L} where @var{yyyy} and
@var{mm} are the year and month of the Standard version. This signifies @var{mm} are the year and month of the Standard version. This signifies
which version of the C Standard the compiler conforms to. Like which version of the C Standard the compiler conforms to. Like
@samp{__STDC__}, this is not necessarily accurate for the entire @code{__STDC__}, this is not necessarily accurate for the entire
implementation, unless GNU CPP is being used with GNU CC. implementation, unless GNU CPP is being used with GCC.
The value @samp{199409L} signifies the 1989 C standard as amended in The value @code{199409L} signifies the 1989 C standard as amended in
1994, which is the current default; the value @samp{199901L} signifies 1994, which is the current default; the value @code{199901L} signifies
the 1999 revision of the C standard. Support for the 1999 revision is the 1999 revision of the C standard. Support for the 1999 revision is
not yet complete. not yet complete.
...@@ -1816,11 +1820,11 @@ facilities of the standard C library available. ...@@ -1816,11 +1820,11 @@ facilities of the standard C library available.
@item __cplusplus @item __cplusplus
This macro is defined when the C++ compiler is in use. You can use This macro is defined when the C++ compiler is in use. You can use
@samp{__cplusplus} to test whether a header is compiled by a C compiler @code{__cplusplus} to test whether a header is compiled by a C compiler
or a C++ compiler. This macro is similar to @samp{__STDC_VERSION__}, in or a C++ compiler. This macro is similar to @code{__STDC_VERSION__}, in
that it expands to a version number. A fully conforming implementation that it expands to a version number. A fully conforming implementation
of the 1998 C++ standard will define this macro to @samp{199711L}. The of the 1998 C++ standard will define this macro to @code{199711L}. The
GNU C++ compiler is not yet fully conforming, so it uses @samp{1} GNU C++ compiler is not yet fully conforming, so it uses @code{1}
instead. We hope to complete our implementation in the near future. instead. We hope to complete our implementation in the near future.
@end table @end table
...@@ -1847,8 +1851,6 @@ constants. For example, GCC 3.2.1 will define @code{__GNUC__} to 3, ...@@ -1847,8 +1851,6 @@ constants. For example, GCC 3.2.1 will define @code{__GNUC__} to 3,
are defined only when the entire compiler is in use; if you invoke the are defined only when the entire compiler is in use; if you invoke the
preprocessor directly, they are not defined. preprocessor directly, they are not defined.
@code{__GNUC_PATCHLEVEL__} is new to GCC 3.0; it is also present in the @code{__GNUC_PATCHLEVEL__} is new to GCC 3.0; it is also present in the
widely-used development snapshots leading up to 3.0 (which identify widely-used development snapshots leading up to 3.0 (which identify
themselves as GCC 2.96 or 2.97, depending on which snapshot you have). themselves as GCC 2.96 or 2.97, depending on which snapshot you have).
...@@ -1858,28 +1860,42 @@ by GCC, you can simply test @code{__GNUC__}. If you need to write code ...@@ -1858,28 +1860,42 @@ by GCC, you can simply test @code{__GNUC__}. If you need to write code
which depends on a specific version, you must be more careful. Each which depends on a specific version, you must be more careful. Each
time the minor version is increased, the patch level is reset to zero; time the minor version is increased, the patch level is reset to zero;
each time the major version is increased (which happens rarely), the each time the major version is increased (which happens rarely), the
minor version and patch level are reset. The simplest way to write the minor version and patch level are reset. If you wish to use the
conditional is like this: predefined macros directly in the conditional, you will need to write it
like this:
@example @example
/* @r{Test for GCC > 3.2.0} */ /* @r{Test for GCC > 3.2.0} */
#if __GNUC__ > 3 || __GNUC_MINOR__ > 2 \ #if __GNUC__ > 3 || \
|| __GNUC_PATCHLEVEL__ > 0 (__GNUC__ == 3 && (__GNUC_MINOR__ > 2 || \
(__GNUC_MINOR__ == 2 && \
__GNUC_PATCHLEVEL__ > 0))
@end example @end example
@noindent @noindent
This takes advantage of the rule that an undefined macro evaluates to Another approach is to use the predefined macros to
zero in an @samp{#if}. The conditional will be false if calculate a single number, then compare that against a threshold:
@code{__GNUC__} is not defined (that is, if you are not using @w{GNU CC}).
@example
#define GCC_VERSION (__GNUC__ * 10000 \
+ __GNUC_MINOR__ * 100 \
+ __GNUC_PATCHLEVEL__)
@dots{}
/* @r{Test for GCC > 3.2.0} */
#if GCC_VERSION > 30200
@end example
@noindent
Many people find this form easier to understand.
@item __GNUG__ @item __GNUG__
The GNU C++ compiler defines this. Testing it is equivalent to The GNU C++ compiler defines this. Testing it is equivalent to
testing @samp{(__GNUC__ && __cplusplus)}. testing @code{@w{(__GNUC__ && __cplusplus)}}.
@item __STRICT_ANSI__ @item __STRICT_ANSI__
GNU C defines this macro if and only if the @option{-ansi} switch, or a GCC defines this macro if and only if the @option{-ansi} switch, or a
@option{-std} switch specifying strict conformance to some version of ISO C, @option{-std} switch specifying strict conformance to some version of ISO C,
was specified when GNU C was invoked. Its definition is the null string. was specified when GCC was invoked. Its definition is the null string.
This macro exists primarily to direct GNU libc's header files to This macro exists primarily to direct GNU libc's header files to
restrict their definitions to the minimal set found in the 1989 C restrict their definitions to the minimal set found in the 1989 C
standard. standard.
...@@ -1919,7 +1935,7 @@ sure that programs will execute with the same effect whether or not they ...@@ -1919,7 +1935,7 @@ sure that programs will execute with the same effect whether or not they
are defined. If they are defined, their value is 1. are defined. If they are defined, their value is 1.
@item __CHAR_UNSIGNED__ @item __CHAR_UNSIGNED__
GNU C defines this macro if and only if the data type @code{char} is GCC defines this macro if and only if the data type @code{char} is
unsigned on the target machine. It exists to cause the standard header unsigned on the target machine. It exists to cause the standard header
file @file{limits.h} to work correctly. You should not use this macro file @file{limits.h} to work correctly. You should not use this macro
yourself; instead, refer to the standard macros defined in @file{limits.h}. yourself; instead, refer to the standard macros defined in @file{limits.h}.
...@@ -1928,15 +1944,15 @@ yourself; instead, refer to the standard macros defined in @file{limits.h}. ...@@ -1928,15 +1944,15 @@ yourself; instead, refer to the standard macros defined in @file{limits.h}.
This macro expands to a single token (not a string constant) which is This macro expands to a single token (not a string constant) which is
the prefix applied to CPU register names in assembly language for this the prefix applied to CPU register names in assembly language for this
target. You can use it to write assembly that is usable in multiple target. You can use it to write assembly that is usable in multiple
environments. For example, in the @samp{m68k-aout} environment it environments. For example, in the @code{m68k-aout} environment it
expands to nothing, but in the @samp{m68k-coff} environment it expands expands to nothing, but in the @code{m68k-coff} environment it expands
to a single @samp{%}. to a single @samp{%}.
@item __USER_LABEL_PREFIX__ @item __USER_LABEL_PREFIX__
This macro expands to a single token which is the the prefix applied to This macro expands to a single token which is the the prefix applied to
user labels (symbols visible to C code) in assembly. For example, in user labels (symbols visible to C code) in assembly. For example, in
the @samp{m68k-aout} environment it expands to an @samp{_}, but in the the @code{m68k-aout} environment it expands to an @samp{_}, but in the
@samp{m68k-coff} environment it expands to nothing. @code{m68k-coff} environment it expands to nothing.
This macro will have the correct definition even if This macro will have the correct definition even if
@option{-f(no-)underscores} is in use, but it will not be correct if @option{-f(no-)underscores} is in use, but it will not be correct if
...@@ -1965,9 +1981,9 @@ the typedefs. ...@@ -1965,9 +1981,9 @@ the typedefs.
The C preprocessor normally predefines several macros that indicate what The C preprocessor normally predefines several macros that indicate what
type of system and machine is in use. They are obviously different on type of system and machine is in use. They are obviously different on
each target supported by GNU C@. This manual, being for all systems and each target supported by GCC@. This manual, being for all systems and
machines, cannot tell you what their names are, but you can use machines, cannot tell you what their names are, but you can use
@samp{cpp -dM} to see them all. @xref{Invocation}. All system-specific @command{cpp -dM} to see them all. @xref{Invocation}. All system-specific
predefined macros expand to the constant 1, so you can test them with predefined macros expand to the constant 1, so you can test them with
either @samp{#ifdef} or @samp{#if}. either @samp{#ifdef} or @samp{#if}.
...@@ -1976,11 +1992,11 @@ The C standard requires that all system-specific macros be part of the ...@@ -1976,11 +1992,11 @@ The C standard requires that all system-specific macros be part of the
or an underscore and a capital letter, are reserved for the compiler and or an underscore and a capital letter, are reserved for the compiler and
library to use as they wish. However, historically system-specific library to use as they wish. However, historically system-specific
macros have had names with no special prefix; for instance, it is common macros have had names with no special prefix; for instance, it is common
to find @samp{unix} defined on Unix systems. For all such macros, GCC to find @code{unix} defined on Unix systems. For all such macros, GCC
provides a parallel macro with two underscores added at the beginning provides a parallel macro with two underscores added at the beginning
and the end. If @samp{unix} is defined, @samp{__unix__} will be defined and the end. If @code{unix} is defined, @code{__unix__} will be defined
too. There will never be more than two underscores; the parallel of too. There will never be more than two underscores; the parallel of
@samp{_mips} is @samp{__mips__}. @code{_mips} is @code{__mips__}.
When the @option{-ansi} option, or any @option{-std} option that When the @option{-ansi} option, or any @option{-std} option that
requests strict conformance, is given to the compiler, all the requests strict conformance, is given to the compiler, all the
...@@ -1994,7 +2010,7 @@ encourage you to correct older code to use the parallel macros whenever ...@@ -1994,7 +2010,7 @@ encourage you to correct older code to use the parallel macros whenever
you find it. We don't recommend you use the system-specific macros that you find it. We don't recommend you use the system-specific macros that
are in the reserved namespace, either. It is better in the long run to are in the reserved namespace, either. It is better in the long run to
check specifically for features you need, using a tool such as check specifically for features you need, using a tool such as
@docref{autoconf}. @command{autoconf}.
@node C++ Named Operators @node C++ Named Operators
@subsection C++ Named Operators @subsection C++ Named Operators
...@@ -2156,8 +2172,8 @@ Suppose you define a macro as follows, ...@@ -2156,8 +2172,8 @@ Suppose you define a macro as follows,
@noindent @noindent
whose purpose is to divide, rounding up. (One use for this operation is whose purpose is to divide, rounding up. (One use for this operation is
to compute how many @samp{int} objects are needed to hold a certain to compute how many @code{int} objects are needed to hold a certain
number of @samp{char} objects.) Then suppose it is used as follows: number of @code{char} objects.) Then suppose it is used as follows:
@example @example
a = ceil_div (b & c, sizeof (int)); a = ceil_div (b & c, sizeof (int));
...@@ -2189,9 +2205,9 @@ Defining the macro as ...@@ -2189,9 +2205,9 @@ Defining the macro as
@noindent @noindent
provides the desired result. provides the desired result.
Unintended grouping can result in another way. Consider @samp{sizeof Unintended grouping can result in another way. Consider @code{sizeof
ceil_div(1, 2)}. That has the appearance of a C expression that would ceil_div(1, 2)}. That has the appearance of a C expression that would
compute the size of the type of @samp{ceil_div (1, 2)}, but in fact it compute the size of the type of @code{ceil_div (1, 2)}, but in fact it
means something very different. Here is what it expands to: means something very different. Here is what it expands to:
@example @example
...@@ -2200,11 +2216,11 @@ sizeof ((1) + (2) - 1) / (2) ...@@ -2200,11 +2216,11 @@ sizeof ((1) + (2) - 1) / (2)
@noindent @noindent
This would take the size of an integer and divide it by two. The This would take the size of an integer and divide it by two. The
precedence rules have put the division outside the @samp{sizeof} when it precedence rules have put the division outside the @code{sizeof} when it
was intended to be inside. was intended to be inside.
Parentheses around the entire macro definition prevent such problems. Parentheses around the entire macro definition prevent such problems.
Here, then, is the recommended way to define @samp{ceil_div}: Here, then, is the recommended way to define @code{ceil_div}:
@example @example
#define ceil_div(x, y) (((x) + (y) - 1) / (y)) #define ceil_div(x, y) (((x) + (y) - 1) / (y))
...@@ -2216,7 +2232,7 @@ Here, then, is the recommended way to define @samp{ceil_div}: ...@@ -2216,7 +2232,7 @@ Here, then, is the recommended way to define @samp{ceil_div}:
Often it is desirable to define a macro that expands into a compound Often it is desirable to define a macro that expands into a compound
statement. Consider, for example, the following macro, that advances a statement. Consider, for example, the following macro, that advances a
pointer (the argument @samp{p} says where to find it) across whitespace pointer (the argument @code{p} says where to find it) across whitespace
characters: characters:
@example @example
...@@ -2232,14 +2248,14 @@ Here backslash-newline is used to split the macro definition, which must ...@@ -2232,14 +2248,14 @@ Here backslash-newline is used to split the macro definition, which must
be a single logical line, so that it resembles the way such code would be a single logical line, so that it resembles the way such code would
be laid out if not part of a macro definition. be laid out if not part of a macro definition.
A call to this macro might be @samp{SKIP_SPACES (p, lim)}. Strictly A call to this macro might be @code{SKIP_SPACES (p, lim)}. Strictly
speaking, the call expands to a compound statement, which is a complete speaking, the call expands to a compound statement, which is a complete
statement with no need for a semicolon to end it. However, since it statement with no need for a semicolon to end it. However, since it
looks like a function call, it minimizes confusion if you can use it looks like a function call, it minimizes confusion if you can use it
like a function call, writing a semicolon afterward, as in like a function call, writing a semicolon afterward, as in
@samp{SKIP_SPACES (p, lim);} @code{SKIP_SPACES (p, lim);}
This can cause trouble before @samp{else} statements, because the This can cause trouble before @code{else} statements, because the
semicolon is actually a null statement. Suppose you write semicolon is actually a null statement. Suppose you write
@example @example
...@@ -2249,12 +2265,12 @@ else @dots{} ...@@ -2249,12 +2265,12 @@ else @dots{}
@end example @end example
@noindent @noindent
The presence of two statements --- the compound statement and a null The presence of two statements---the compound statement and a null
statement --- in between the @samp{if} condition and the @samp{else} statement---in between the @code{if} condition and the @code{else}
makes invalid C code. makes invalid C code.
The definition of the macro @samp{SKIP_SPACES} can be altered to solve The definition of the macro @code{SKIP_SPACES} can be altered to solve
this problem, using a @samp{do @dots{} while} statement. Here is how: this problem, using a @code{do @dots{} while} statement. Here is how:
@example @example
#define SKIP_SPACES(p, limit) \ #define SKIP_SPACES(p, limit) \
...@@ -2265,7 +2281,7 @@ do @{ char *lim = (limit); \ ...@@ -2265,7 +2281,7 @@ do @{ char *lim = (limit); \
while (0) while (0)
@end example @end example
Now @samp{SKIP_SPACES (p, lim);} expands into Now @code{SKIP_SPACES (p, lim);} expands into
@example @example
do @{@dots{}@} while (0); do @{@dots{}@} while (0);
...@@ -2280,7 +2296,7 @@ generate no extra code for it. ...@@ -2280,7 +2296,7 @@ generate no extra code for it.
@cindex side effects (in macro arguments) @cindex side effects (in macro arguments)
@cindex unsafe macros @cindex unsafe macros
Many C programs define a macro @samp{min}, for ``minimum'', like this: Many C programs define a macro @code{min}, for ``minimum'', like this:
@example @example
#define min(X, Y) ((X) < (Y) ? (X) : (Y)) #define min(X, Y) ((X) < (Y) ? (X) : (Y))
...@@ -2301,18 +2317,18 @@ next = ((x + y) < (foo (z)) ? (x + y) : (foo (z))); ...@@ -2301,18 +2317,18 @@ next = ((x + y) < (foo (z)) ? (x + y) : (foo (z)));
@end example @end example
@noindent @noindent
where @samp{x + y} has been substituted for @samp{X} and @samp{foo (z)} where @code{x + y} has been substituted for @code{X} and @code{foo (z)}
for @samp{Y}. for @code{Y}.
The function @samp{foo} is used only once in the statement as it appears The function @code{foo} is used only once in the statement as it appears
in the program, but the expression @samp{foo (z)} has been substituted in the program, but the expression @code{foo (z)} has been substituted
twice into the macro expansion. As a result, @samp{foo} might be called twice into the macro expansion. As a result, @code{foo} might be called
two times when the statement is executed. If it has side effects or if two times when the statement is executed. If it has side effects or if
it takes a long time to compute, the results might not be what you it takes a long time to compute, the results might not be what you
intended. We say that @samp{min} is an @dfn{unsafe} macro. intended. We say that @code{min} is an @dfn{unsafe} macro.
The best solution to this problem is to define @samp{min} in a way that The best solution to this problem is to define @code{min} in a way that
computes the value of @samp{foo (z)} only once. The C language offers computes the value of @code{foo (z)} only once. The C language offers
no standard way to do this, but it can be done with GNU extensions as no standard way to do this, but it can be done with GNU extensions as
follows: follows:
...@@ -2331,21 +2347,23 @@ the risk of conflict with an identifier of wider scope (it is impossible ...@@ -2331,21 +2347,23 @@ the risk of conflict with an identifier of wider scope (it is impossible
to avoid this entirely). Now each argument is evaluated exactly once. to avoid this entirely). Now each argument is evaluated exactly once.
If you do not wish to use GNU C extensions, the only solution is to be If you do not wish to use GNU C extensions, the only solution is to be
careful when @emph{using} the macro @samp{min}. For example, you can careful when @emph{using} the macro @code{min}. For example, you can
calculate the value of @samp{foo (z)}, save it in a variable, and use calculate the value of @code{foo (z)}, save it in a variable, and use
that variable in @samp{min}: that variable in @code{min}:
@example @example
@group
#define min(X, Y) ((X) < (Y) ? (X) : (Y)) #define min(X, Y) ((X) < (Y) ? (X) : (Y))
@dots{} @dots{}
@{ @{
int tem = foo (z); int tem = foo (z);
next = min (x + y, tem); next = min (x + y, tem);
@} @}
@end group
@end example @end example
@noindent @noindent
(where we assume that @samp{foo} returns type @samp{int}). (where we assume that @code{foo} returns type @code{int}).
@node Self-Referential Macros @node Self-Referential Macros
@subsection Self-Referential Macros @subsection Self-Referential Macros
...@@ -2363,22 +2381,22 @@ the preprocessor output unchanged. Let's consider an example: ...@@ -2363,22 +2381,22 @@ the preprocessor output unchanged. Let's consider an example:
@end example @end example
@noindent @noindent
where @samp{foo} is also a variable in your program. where @code{foo} is also a variable in your program.
Following the ordinary rules, each reference to @samp{foo} will expand Following the ordinary rules, each reference to @code{foo} will expand
into @samp{(4 + foo)}; then this will be rescanned and will expand into into @code{(4 + foo)}; then this will be rescanned and will expand into
@samp{(4 + (4 + foo))}; and so on until the computer runs out of memory. @code{(4 + (4 + foo))}; and so on until the computer runs out of memory.
The self-reference rule cuts this process short after one step, at The self-reference rule cuts this process short after one step, at
@samp{(4 + foo)}. Therefore, this macro definition has the possibly @code{(4 + foo)}. Therefore, this macro definition has the possibly
useful effect of causing the program to add 4 to the value of @samp{foo} useful effect of causing the program to add 4 to the value of @code{foo}
wherever @samp{foo} is referred to. wherever @code{foo} is referred to.
In most cases, it is a bad idea to take advantage of this feature. A In most cases, it is a bad idea to take advantage of this feature. A
person reading the program who sees that @samp{foo} is a variable will person reading the program who sees that @code{foo} is a variable will
not expect that it is a macro as well. The reader will come across the not expect that it is a macro as well. The reader will come across the
identifier @samp{foo} in the program and think its value should be that identifier @code{foo} in the program and think its value should be that
of the variable @samp{foo}, whereas in fact the value is four greater. of the variable @code{foo}, whereas in fact the value is four greater.
One common, useful use of self-reference is to create a macro which One common, useful use of self-reference is to create a macro which
expands to itself. If you write expands to itself. If you write
...@@ -2388,10 +2406,10 @@ expands to itself. If you write ...@@ -2388,10 +2406,10 @@ expands to itself. If you write
@end example @end example
@noindent @noindent
then the macro @code{EPERM} expands to @samp{EPERM}. Effectively, it is then the macro @code{EPERM} expands to @code{EPERM}. Effectively, it is
left alone by the preprocessor whenever it's used in running text. You left alone by the preprocessor whenever it's used in running text. You
can tell that it's a macro with @samp{#ifdef}. You might do this if you can tell that it's a macro with @samp{#ifdef}. You might do this if you
want to define numeric constants with an @samp{enum}, but have want to define numeric constants with an @code{enum}, but have
@samp{#ifdef} be true for each constant. @samp{#ifdef} be true for each constant.
If a macro @code{x} expands to use a macro @code{y}, and the expansion of If a macro @code{x} expands to use a macro @code{y}, and the expansion of
...@@ -2405,7 +2423,7 @@ either. Thus, if we have ...@@ -2405,7 +2423,7 @@ either. Thus, if we have
@end example @end example
@noindent @noindent
then @samp{x} and @samp{y} expand as follows: then @code{x} and @code{y} expand as follows:
@example @example
@group @group
...@@ -2458,12 +2476,12 @@ that the prescan does make a difference in three special cases: ...@@ -2458,12 +2476,12 @@ that the prescan does make a difference in three special cases:
Nested calls to a macro. Nested calls to a macro.
We say that @dfn{nested} calls to a macro occur when a macro's argument We say that @dfn{nested} calls to a macro occur when a macro's argument
contains a call to that very macro. For example, if @samp{f} is a macro contains a call to that very macro. For example, if @code{f} is a macro
that expects one argument, @samp{f (f (1))} is a nested pair of calls to that expects one argument, @code{f (f (1))} is a nested pair of calls to
@samp{f}. The desired expansion is made by expanding @samp{f (1)} and @code{f}. The desired expansion is made by expanding @code{f (1)} and
substituting that into the definition of @samp{f}. The prescan causes substituting that into the definition of @code{f}. The prescan causes
the expected result to happen. Without the prescan, @samp{f (1)} itself the expected result to happen. Without the prescan, @code{f (1)} itself
would be substituted as an argument, and the inner use of @samp{f} would would be substituted as an argument, and the inner use of @code{f} would
appear during the main scan as an indirect self-reference and would not appear during the main scan as an indirect self-reference and would not
be expanded. be expanded.
...@@ -2483,9 +2501,9 @@ instance, if you have ...@@ -2483,9 +2501,9 @@ instance, if you have
#define BUFSIZE TABLESIZE #define BUFSIZE TABLESIZE
@end example @end example
then @samp{AFTERX(BUFSIZE)} expands to @samp{X_BUFSIZE}, and then @code{AFTERX(BUFSIZE)} expands to @code{X_BUFSIZE}, and
@samp{XAFTERX(BUFSIZE)} expands to @samp{X_1024}. (Not to @code{XAFTERX(BUFSIZE)} expands to @code{X_1024}. (Not to
@samp{X_TABLESIZE}. Prescan always does a complete expansion.) @code{X_TABLESIZE}. Prescan always does a complete expansion.)
@item @item
Macros used in arguments, whose expansions contain unshielded commas. Macros used in arguments, whose expansions contain unshielded commas.
...@@ -2499,9 +2517,9 @@ wrong number of arguments. Here is an example: ...@@ -2499,9 +2517,9 @@ wrong number of arguments. Here is an example:
#define lose(x) (1 + (x)) #define lose(x) (1 + (x))
@end example @end example
We would like @samp{bar(foo)} to turn into @samp{(1 + (foo))}, which We would like @code{bar(foo)} to turn into @code{(1 + (foo))}, which
would then turn into @samp{(1 + (a,b))}. Instead, @samp{bar(foo)} would then turn into @code{(1 + (a,b))}. Instead, @code{bar(foo)}
expands into @samp{lose(a,b)}, and you get an error because @code{lose} expands into @code{lose(a,b)}, and you get an error because @code{lose}
requires a single argument. In this case, the problem is easily solved requires a single argument. In this case, the problem is easily solved
by the same parentheses that ought to be used to prevent misnesting of by the same parentheses that ought to be used to prevent misnesting of
arithmetic operations: arithmetic operations:
...@@ -2538,8 +2556,8 @@ ignore_second_arg (foo (), ...@@ -2538,8 +2556,8 @@ ignore_second_arg (foo (),
@end example @end example
@noindent @noindent
The syntax error triggered by the tokens @samp{syntax error} results in The syntax error triggered by the tokens @code{syntax error} results in
an error message citing line three --- the line of ignore_second_arg --- an error message citing line three---the line of ignore_second_arg---
even though the problematic code comes from line five. even though the problematic code comes from line five.
We consider this a bug, and intend to fix it in the near future. We consider this a bug, and intend to fix it in the near future.
...@@ -2552,11 +2570,11 @@ A @dfn{conditional} is a directive that instructs the preprocessor to ...@@ -2552,11 +2570,11 @@ A @dfn{conditional} is a directive that instructs the preprocessor to
select whether or not to include a chunk of code in the final token select whether or not to include a chunk of code in the final token
stream passed to the compiler. Preprocessor conditionals can test stream passed to the compiler. Preprocessor conditionals can test
arithmetic expressions, or whether a name is defined as a macro, or both arithmetic expressions, or whether a name is defined as a macro, or both
simultaneously using the special @samp{defined} operator. simultaneously using the special @code{defined} operator.
A conditional in the C preprocessor resembles in some ways an @samp{if} A conditional in the C preprocessor resembles in some ways an @code{if}
statement in C, but it is important to understand the difference between statement in C, but it is important to understand the difference between
them. The condition in an @samp{if} statement is tested during the them. The condition in an @code{if} statement is tested during the
execution of your program. Its purpose is to allow your program to execution of your program. Its purpose is to allow your program to
behave differently from run to run, depending on the data it is behave differently from run to run, depending on the data it is
operating on. The condition in a preprocessing conditional directive is operating on. The condition in a preprocessing conditional directive is
...@@ -2565,16 +2583,16 @@ code to be included in the program depending on the situation at the ...@@ -2565,16 +2583,16 @@ code to be included in the program depending on the situation at the
time of compilation. time of compilation.
However, the distinction is becoming less clear. Modern compilers often However, the distinction is becoming less clear. Modern compilers often
do test @samp{if} statements when a program is compiled, if their do test @code{if} statements when a program is compiled, if their
conditions are known not to vary at run time, and eliminate code which conditions are known not to vary at run time, and eliminate code which
can never be executed. If you can count on your compiler to do this, can never be executed. If you can count on your compiler to do this,
you may find that your program is more readable if you use @samp{if} you may find that your program is more readable if you use @code{if}
statements with constant conditions (perhaps determined by macros). Of statements with constant conditions (perhaps determined by macros). Of
course, you can only use this to exclude code, not type definitions or course, you can only use this to exclude code, not type definitions or
other preprocessing directives, and you can only do it if the code other preprocessing directives, and you can only do it if the code
remains syntactically valid when it is not to be used. remains syntactically valid when it is not to be used.
GNU C version 3 eliminates this kind of never-executed code even when GCC version 3 eliminates this kind of never-executed code even when
not optimizing. Older versions did it only when optimizing. not optimizing. Older versions did it only when optimizing.
@menu @menu
...@@ -2708,7 +2726,7 @@ Your program might have a special header file (often called ...@@ -2708,7 +2726,7 @@ Your program might have a special header file (often called
@file{config.h}) that is adjusted when the program is compiled. It can @file{config.h}) that is adjusted when the program is compiled. It can
define or not define macros depending on the features of the system and define or not define macros depending on the features of the system and
the desired capabilities of the program. The adjustment can be the desired capabilities of the program. The adjustment can be
automated by a tool such as @docref{autoconf}, or done by hand. automated by a tool such as @command{autoconf}, or done by hand.
@end itemize @end itemize
@node If @node If
...@@ -2741,7 +2759,7 @@ code. ...@@ -2741,7 +2759,7 @@ code.
@item @item
Arithmetic operators for addition, subtraction, multiplication, Arithmetic operators for addition, subtraction, multiplication,
division, bitwise operations, shifts, comparisons, and logical division, bitwise operations, shifts, comparisons, and logical
operations (@samp{&&} and @samp{||}). The latter two obey the usual operations (@code{&&} and @code{||}). The latter two obey the usual
short-circuiting rules of standard C. short-circuiting rules of standard C.
@item @item
...@@ -2749,13 +2767,13 @@ Macros. All macros in the expression are expanded before actual ...@@ -2749,13 +2767,13 @@ Macros. All macros in the expression are expanded before actual
computation of the expression's value begins. computation of the expression's value begins.
@item @item
Uses of the @samp{defined} operator, which lets you check whether macros Uses of the @code{defined} operator, which lets you check whether macros
are defined in the middle of an @samp{#if}. are defined in the middle of an @samp{#if}.
@item @item
Identifiers that are not macros, which are all considered to be the Identifiers that are not macros, which are all considered to be the
number zero. This allows you to write @samp{@w{#if MACRO}} instead of number zero. This allows you to write @code{@w{#if MACRO}} instead of
@samp{@w{#ifdef MACRO}}, if you know that MACRO, when defined, will @code{@w{#ifdef MACRO}}, if you know that MACRO, when defined, will
always have a nonzero value. Function-like macros used without their always have a nonzero value. Function-like macros used without their
function call parentheses are also treated as zero. function call parentheses are also treated as zero.
...@@ -2785,14 +2803,14 @@ treats the conditional as having failed. ...@@ -2785,14 +2803,14 @@ treats the conditional as having failed.
@subsection Defined @subsection Defined
@cindex @code{defined} @cindex @code{defined}
The special operator @samp{defined} is used in @samp{#if} and The special operator @code{defined} is used in @samp{#if} and
@samp{#elif} expressions to test whether a certain name is defined as a @samp{#elif} expressions to test whether a certain name is defined as a
macro. @samp{defined @var{name}} and @samp{defined (@var{name})} are macro. @code{defined @var{name}} and @code{defined (@var{name})} are
both expressions whose value is 1 if @var{name} is defined as a macro at both expressions whose value is 1 if @var{name} is defined as a macro at
the current point in the program, and 0 otherwise. Thus, @samp{@w{#if the current point in the program, and 0 otherwise. Thus, @code{@w{#if
defined MACRO}} is precisely equivalent to @samp{@w{#ifdef MACRO}}. defined MACRO}} is precisely equivalent to @code{@w{#ifdef MACRO}}.
@samp{defined} is useful when you wish to test more than one macro for @code{defined} is useful when you wish to test more than one macro for
existence at once. For example, existence at once. For example,
@example @example
...@@ -2800,8 +2818,8 @@ existence at once. For example, ...@@ -2800,8 +2818,8 @@ existence at once. For example,
@end example @end example
@noindent @noindent
would succeed if either of the names @samp{__vax__} or would succeed if either of the names @code{__vax__} or
@samp{__ns16000__} is defined as a macro. @code{__ns16000__} is defined as a macro.
Conditionals written like this: Conditionals written like this:
...@@ -2810,13 +2828,13 @@ Conditionals written like this: ...@@ -2810,13 +2828,13 @@ Conditionals written like this:
@end example @end example
@noindent @noindent
can generally be simplified to just @samp{@w{#if BUFSIZE >= 1024}}, can generally be simplified to just @code{@w{#if BUFSIZE >= 1024}},
since if @samp{BUFSIZE} is not defined, it will be interpreted as having since if @code{BUFSIZE} is not defined, it will be interpreted as having
the value zero. the value zero.
If the @samp{defined} operator appears as a result of a macro expansion, If the @code{defined} operator appears as a result of a macro expansion,
the C standard says the behavior is undefined. GNU cpp treats it as a the C standard says the behavior is undefined. GNU cpp treats it as a
genuine @samp{defined} operator and evaluates it normally. It will warn genuine @code{defined} operator and evaluates it normally. It will warn
wherever your code uses this feature if you use the command-line option wherever your code uses this feature if you use the command-line option
@option{-pedantic}, since other compilers may handle it differently. @option{-pedantic}, since other compilers may handle it differently.
...@@ -2829,13 +2847,16 @@ alternative text to be used if the condition fails. This is what it ...@@ -2829,13 +2847,16 @@ alternative text to be used if the condition fails. This is what it
looks like: looks like:
@example @example
@group
#if @var{expression} #if @var{expression}
@var{text-if-true} @var{text-if-true}
#else /* Not @var{expression} */ #else /* Not @var{expression} */
@var{text-if-false} @var{text-if-false}
#endif /* Not @var{expression} */ #endif /* Not @var{expression} */
@end group
@end example @end example
@noindent
If @var{expression} is nonzero, the @var{text-if-true} is included and If @var{expression} is nonzero, the @var{text-if-true} is included and
the @var{text-if-false} is skipped. If @var{expression} is zero, the the @var{text-if-false} is skipped. If @var{expression} is zero, the
opposite happens. opposite happens.
...@@ -2900,20 +2921,20 @@ code will end the commenting-out. The probable result is a flood of ...@@ -2900,20 +2921,20 @@ code will end the commenting-out. The probable result is a flood of
syntax errors. syntax errors.
One way to avoid this problem is to use an always-false conditional One way to avoid this problem is to use an always-false conditional
instead. For instance, put @samp{#if 0} before the deleted code and instead. For instance, put @code{#if 0} before the deleted code and
@samp{#endif} after it. This This works even if the code being turned @code{#endif} after it. This This works even if the code being turned
off contains conditionals, but they must be entire conditionals off contains conditionals, but they must be entire conditionals
(balanced @samp{#if} and @samp{#endif}). (balanced @samp{#if} and @samp{#endif}).
Some people use @samp{#ifdef notdef} instead. This is risky, because Some people use @code{#ifdef notdef} instead. This is risky, because
@samp{notdef} might be accidentally defined as a macro, and then the @code{notdef} might be accidentally defined as a macro, and then the
conditional would succeed. @samp{#if 0} can be counted on to fail. conditional would succeed. @code{#if 0} can be counted on to fail.
Do not use @samp{#if 0} for comments which are not C code. Use a real Do not use @code{#if 0} for comments which are not C code. Use a real
comment, instead. The interior of @samp{#if 0} must consist of complete comment, instead. The interior of @code{#if 0} must consist of complete
tokens; in particular, single-quote characters must balance. Comments tokens; in particular, single-quote characters must balance. Comments
often contain unbalanced single-quote characters (known in English as often contain unbalanced single-quote characters (known in English as
apostrophes). These confuse @samp{#if 0}. They don't confuse apostrophes). These confuse @code{#if 0}. They don't confuse
@samp{/*}. @samp{/*}.
@node Diagnostics @node Diagnostics
...@@ -2975,15 +2996,15 @@ reported as having appeared on the line of the source file where the ...@@ -2975,15 +2996,15 @@ reported as having appeared on the line of the source file where the
outermost macro was used. We intend to be more accurate in the future. outermost macro was used. We intend to be more accurate in the future.
If you write a program which generates source code, such as the If you write a program which generates source code, such as the
@code{bison} parser generator, you may want to adjust the preprocessor's @command{bison} parser generator, you may want to adjust the preprocessor's
notion of the current file name and line number by hand. Parts of the notion of the current file name and line number by hand. Parts of the
output from @code{bison} are generated from scratch, other parts come output from @command{bison} are generated from scratch, other parts come
from a standard parser file. The rest are copied verbatim from from a standard parser file. The rest are copied verbatim from
@code{bison}'s input. You would like compiler error messages and @command{bison}'s input. You would like compiler error messages and
symbolic debuggers to be able to refer to @code{bison}'s input file. symbolic debuggers to be able to refer to @code{bison}'s input file.
@findex #line @findex #line
@code{bison} or any such program can arrange this by writing @command{bison} or any such program can arrange this by writing
@samp{#line} directives into the output file. @samp{#line} is a @samp{#line} directives into the output file. @samp{#line} is a
directive that specifies the original line number and source file name directive that specifies the original line number and source file name
for subsequent input in the current preprocessor input file. for subsequent input in the current preprocessor input file.
...@@ -3027,27 +3048,27 @@ conveyed in the language itself. Three forms of this directive ...@@ -3027,27 +3048,27 @@ conveyed in the language itself. Three forms of this directive
A C compiler is free to attach any meaning it likes to other pragmas. A C compiler is free to attach any meaning it likes to other pragmas.
GCC has historically preferred to use extensions to the syntax of the GCC has historically preferred to use extensions to the syntax of the
language, such as @samp{__attribute__}, for this purpose. However, GCC language, such as @code{__attribute__}, for this purpose. However, GCC
does define a few pragmas of its own. These mostly have effects on the does define a few pragmas of its own. These mostly have effects on the
entire translation unit or source file. entire translation unit or source file.
In GCC version 3, all GNU-defined, supported pragmas have been given a In GCC version 3, all GNU-defined, supported pragmas have been given a
@samp{GCC} prefix. This is in line with the @samp{STDC} prefix on all @code{GCC} prefix. This is in line with the @code{STDC} prefix on all
pragmas defined by C99. For backward compatibility, pragmas which were pragmas defined by C99. For backward compatibility, pragmas which were
recognized by previous versions are still recognized without the recognized by previous versions are still recognized without the
@samp{GCC} prefix, but that usage is deprecated. Some older pragmas are @code{GCC} prefix, but that usage is deprecated. Some older pragmas are
deprecated in their entirety. They are not recognized with the deprecated in their entirety. They are not recognized with the
@samp{GCC} prefix. @xref{Obsolete Features}. @code{GCC} prefix. @xref{Obsolete Features}.
@cindex @code{_Pragma} @cindex @code{_Pragma}
C99 introduces the @samp{_Pragma} operator. This feature addresses a C99 introduces the @code{@w{_Pragma}} operator. This feature addresses a
major problem with @samp{#pragma}: being a directive, it cannot be major problem with @samp{#pragma}: being a directive, it cannot be
produced as the result of macro expansion. @samp{_Pragma} is an produced as the result of macro expansion. @code{@w{_Pragma}} is an
operator, much like @samp{sizeof} or @samp{defined}, and can be embedded operator, much like @code{sizeof} or @code{defined}, and can be embedded
in a macro. in a macro.
The syntax is @code{_Pragma (string-literal)}, where Its syntax is @code{@w{_Pragma (@var{string-literal})}}, where
@samp{string-literal} can be either a normal or wide-character string @var{string-literal} can be either a normal or wide-character string
literal. It is destringized, by replacing all @samp{\\} with a single literal. It is destringized, by replacing all @samp{\\} with a single
@samp{\} and all @samp{\"} with a @samp{"}. The result is then @samp{\} and all @samp{\"} with a @samp{"}. The result is then
processed as if it had appeared as the right hand side of a processed as if it had appeared as the right hand side of a
...@@ -3058,7 +3079,7 @@ _Pragma ("GCC dependency \"parse.y\"") ...@@ -3058,7 +3079,7 @@ _Pragma ("GCC dependency \"parse.y\"")
@end example @end example
@noindent @noindent
has the same effect as @samp{#pragma GCC dependency "parse.y"}. The has the same effect as @code{#pragma GCC dependency "parse.y"}. The
same effect could be achieved using macros, for example same effect could be achieved using macros, for example
@example @example
...@@ -3066,7 +3087,7 @@ same effect could be achieved using macros, for example ...@@ -3066,7 +3087,7 @@ same effect could be achieved using macros, for example
DO_PRAGMA (GCC dependency "parse.y") DO_PRAGMA (GCC dependency "parse.y")
@end example @end example
The standard is unclear on where a @samp{_Pragma} operator can appear. The standard is unclear on where a @code{_Pragma} operator can appear.
The preprocessor accepts it even within a preprocessing conditional The preprocessor accepts it even within a preprocessing conditional
directive like @samp{#if}. To be safe, you are probably best keeping it directive like @samp{#if}. To be safe, you are probably best keeping it
out of directives other than @samp{#define}, and putting it on a line of out of directives other than @samp{#define}, and putting it on a line of
...@@ -3076,9 +3097,9 @@ This manual documents the pragmas which are meaningful to the ...@@ -3076,9 +3097,9 @@ This manual documents the pragmas which are meaningful to the
preprocessor itself. Other pragmas are meaningful to the C or C++ preprocessor itself. Other pragmas are meaningful to the C or C++
compilers. They are documented in the GCC manual. compilers. They are documented in the GCC manual.
@ftable @samp @ftable @code
@item #pragma GCC dependency @item #pragma GCC dependency
@samp{#pragma GCC dependency} allows you to check the relative dates of @code{#pragma GCC dependency} allows you to check the relative dates of
the current file and another file. If the other file is more recent than the current file and another file. If the other file is more recent than
the current file, a warning is issued. This is useful if the current the current file, a warning is issued. This is useful if the current
file is derived from the other file, and should be regenerated. The file is derived from the other file, and should be regenerated. The
...@@ -3095,7 +3116,7 @@ warning message. ...@@ -3095,7 +3116,7 @@ warning message.
Sometimes, there is an identifier that you want to remove completely Sometimes, there is an identifier that you want to remove completely
from your program, and make sure that it never creeps back in. To from your program, and make sure that it never creeps back in. To
enforce this, you can @dfn{poison} the identifier with this pragma. enforce this, you can @dfn{poison} the identifier with this pragma.
@samp{#pragma GCC poison} is followed by a list of identifiers to @code{#pragma GCC poison} is followed by a list of identifiers to
poison. If any of those identifiers appears anywhere in the source poison. If any of those identifiers appears anywhere in the source
after the directive, it is a hard error. For example, after the directive, it is a hard error. For example,
...@@ -3174,14 +3195,14 @@ discarded. ...@@ -3174,14 +3195,14 @@ discarded.
The ISO standard specifies that it is implementation defined whether a The ISO standard specifies that it is implementation defined whether a
preprocessor preserves whitespace between tokens, or replaces it with preprocessor preserves whitespace between tokens, or replaces it with
e.g. a single space. In the GNU C preprocessor, whitespace between e.g. a single space. In GNU CPP, whitespace between tokens is collapsed
tokens is collapsed to become a single space, with the exception that to become a single space, with the exception that the first token on a
the first token on a non-directive line is preceded with sufficient non-directive line is preceded with sufficient spaces that it appears in
spaces that it appears in the same column in the preprocessed output the same column in the preprocessed output that it appeared in in the
that it appeared in in the original source file. This is so the output original source file. This is so the output is easy to read.
is easy to read. @xref{Differences from previous versions}. CPP does @xref{Differences from previous versions}. CPP does not insert any
not insert any whitespace where there was none in the original source, whitespace where there was none in the original source, except where
except where necessary to prevent an accidental token paste. necessary to prevent an accidental token paste.
@cindex linemarkers @cindex linemarkers
Source file name and line number information is conveyed by lines Source file name and line number information is conveyed by lines
...@@ -3211,7 +3232,7 @@ This indicates that the following text comes from a system header file, ...@@ -3211,7 +3232,7 @@ This indicates that the following text comes from a system header file,
so certain warnings should be suppressed. so certain warnings should be suppressed.
@item 4 @item 4
This indicates that the following text should be treated as being This indicates that the following text should be treated as being
wrapped in an implicit @samp{extern "C"} block. wrapped in an implicit @code{extern "C"} block.
@c maybe cross reference NO_IMPLICIT_EXTERN_C @c maybe cross reference NO_IMPLICIT_EXTERN_C
@end table @end table
...@@ -3349,8 +3370,8 @@ The @samp{U} and @samp{LL} integer constant suffixes, which were not ...@@ -3349,8 +3370,8 @@ The @samp{U} and @samp{LL} integer constant suffixes, which were not
available in traditional C@. (Traditional C does support the @samp{L} available in traditional C@. (Traditional C does support the @samp{L}
suffix for simple long integer constants.) You are not warned about suffix for simple long integer constants.) You are not warned about
uses of these suffixes in macros defined in system headers. For uses of these suffixes in macros defined in system headers. For
instance, @samp{UINT_MAX} may well be defined as @samp{4294967295U}, but instance, @code{UINT_MAX} may well be defined as @code{4294967295U}, but
you will not be warned if you use @samp{UINT_MAX}. you will not be warned if you use @code{UINT_MAX}.
You can usually avoid the warning, and the related warning about You can usually avoid the warning, and the related warning about
constants which are so large that they are unsigned, by writing the constants which are so large that they are unsigned, by writing the
...@@ -3404,7 +3425,7 @@ same column as it did in the original source file. ...@@ -3404,7 +3425,7 @@ same column as it did in the original source file.
@item The numeric value of character constants in preprocessor expressions. @item The numeric value of character constants in preprocessor expressions.
The preprocessor and compiler interpret character constants in the same The preprocessor and compiler interpret character constants in the same
way; escape sequences such as @code{\a} are given the values they would way; escape sequences such as @samp{\a} are given the values they would
have on the target machine. have on the target machine.
Multi-character character constants are interpreted a character at a Multi-character character constants are interpreted a character at a
...@@ -3412,7 +3433,7 @@ time, shifting the previous result left by the number of bits per ...@@ -3412,7 +3433,7 @@ time, shifting the previous result left by the number of bits per
character on the host, and adding the new character. For example, 'ab' character on the host, and adding the new character. For example, 'ab'
on an 8-bit host would be interpreted as @w{'a' * 256 + 'b'}. If there on an 8-bit host would be interpreted as @w{'a' * 256 + 'b'}. If there
are more characters in the constant than can fit in the widest native are more characters in the constant than can fit in the widest native
integer type on the host, usually a @samp{long}, the excess characters integer type on the host, usually a @code{long}, the excess characters
are ignored and a diagnostic is given. are ignored and a diagnostic is given.
@item Source file inclusion. @item Source file inclusion.
...@@ -3463,8 +3484,8 @@ The standard requires at least 15 levels. ...@@ -3463,8 +3484,8 @@ The standard requires at least 15 levels.
@item Nesting levels of conditional inclusion. @item Nesting levels of conditional inclusion.
The C standard mandates this be at least 63. The GNU C preprocessor The C standard mandates this be at least 63. GNU CPP is limited only by
is limited only by available memory. available memory.
@item Levels of parenthesised expressions within a full expression. @item Levels of parenthesised expressions within a full expression.
...@@ -3478,7 +3499,7 @@ requires only that the first 63 be significant. ...@@ -3478,7 +3499,7 @@ requires only that the first 63 be significant.
@item Number of macros simultaneously defined in a single translation unit. @item Number of macros simultaneously defined in a single translation unit.
The standard requires at least 4095 be possible; GNU cpp is limited only The standard requires at least 4095 be possible. GNU CPP is limited only
by available memory. by available memory.
@item Number of parameters in a macro definition and arguments in a macro call. @item Number of parameters in a macro definition and arguments in a macro call.
...@@ -3544,8 +3565,8 @@ An assertion looks like this: ...@@ -3544,8 +3565,8 @@ An assertion looks like this:
sequence of tokens; all characters are significant except for leading sequence of tokens; all characters are significant except for leading
and trailing whitespace, and differences in internal whitespace and trailing whitespace, and differences in internal whitespace
sequences are ignored. (This is similar to the rules governing macro sequences are ignored. (This is similar to the rules governing macro
redefinition.) Thus, @samp{(x + y)} is different from @samp{(x+y)} but redefinition.) Thus, @code{(x + y)} is different from @code{(x+y)} but
equivalent to @samp{@w{( x + y )}}. Parentheses do not nest inside an equivalent to @code{@w{( x + y )}}. Parentheses do not nest inside an
answer. answer.
@cindex testing predicates @cindex testing predicates
...@@ -3602,7 +3623,7 @@ You can also make or cancel assertions using command line options. ...@@ -3602,7 +3623,7 @@ You can also make or cancel assertions using command line options.
@node Obsolete once-only headers @node Obsolete once-only headers
@subsection Obsolete once-only headers @subsection Obsolete once-only headers
GNU C supports two more ways of indicating that a header file should be GNU CPP supports two more ways of indicating that a header file should be
read only once. Neither one is as portable as a wrapper @samp{#ifndef}, read only once. Neither one is as portable as a wrapper @samp{#ifndef},
and we recommend you do not use them in new programs. and we recommend you do not use them in new programs.
...@@ -3656,7 +3677,7 @@ between two tokens. It is almost always safe to delete the @samp{##}. ...@@ -3656,7 +3677,7 @@ between two tokens. It is almost always safe to delete the @samp{##}.
@cindex pragma poison @cindex pragma poison
@item @code{#pragma poison} @item @code{#pragma poison}
This is the same as @samp{#pragma GCC poison}. The version without the This is the same as @code{#pragma GCC poison}. The version without the
@code{GCC} prefix is deprecated. @xref{Pragmas}. @code{GCC} prefix is deprecated. @xref{Pragmas}.
@cindex multi-line string constants @cindex multi-line string constants
...@@ -3725,12 +3746,11 @@ versions accepted it silently. ...@@ -3725,12 +3746,11 @@ versions accepted it silently.
@item @samp{##} swallowing preceding text in rest argument macros @item @samp{##} swallowing preceding text in rest argument macros
Formerly, in a macro expansion, if @samp{##} appeared before a variable Formerly, in a macro expansion, if @samp{##} appeared before a variable
arguments parameter, and the set of tokens specified for that argument in arguments parameter, and the set of tokens specified for that argument
the macro invocation was empty, previous versions of the GNU C in the macro invocation was empty, previous versions of GNU CPP would
preprocessor would back up and remove the preceding sequence of back up and remove the preceding sequence of non-whitespace characters
non-whitespace characters (@strong{not} the preceding token). This (@strong{not} the preceding token). This extension is in direct
extension is in direct conflict with the 1999 C standard and has been conflict with the 1999 C standard and has been drastically pared back.
drastically pared back.
In the current version of the preprocessor, if @samp{##} appears between In the current version of the preprocessor, if @samp{##} appears between
a comma and a variable arguments parameter, and the variable argument is a comma and a variable arguments parameter, and the variable argument is
...@@ -3768,10 +3788,10 @@ without notice. ...@@ -3768,10 +3788,10 @@ without notice.
@ignore @ignore
@c man begin SYNOPSIS @c man begin SYNOPSIS
cpp [@option{-D}@var{macro}[=@var{defn}]...] [@option{-U}@var{macro}] cpp [@option{-D}@var{macro}[=@var{defn}]@dots{}] [@option{-U}@var{macro}]
[@option{-I}@var{dir}...] [@option{-W}@var{warn}...] [@option{-I}@var{dir}@dots{}] [@option{-W}@var{warn}@dots{}]
[@option{-M}|@option{-MM}] [@option{-MG}] [@option{-MF} @var{filename}] [@option{-M}|@option{-MM}] [@option{-MG}] [@option{-MF} @var{filename}]
[@option{-MP}] [@option{-MQ} @var{target}...] [@option{-MT} @var{target}...] [@option{-MP}] [@option{-MQ} @var{target}@dots{}] [@option{-MT} @var{target}@dots{}]
[@option{-x} @var{language}] [@option{-std=}@var{standard}] [@option{-x} @var{language}] [@option{-std=}@var{standard}]
@var{infile} @var{outfile} @var{infile} @var{outfile}
...@@ -3801,9 +3821,9 @@ effect. Long options that take arguments require a space between option ...@@ -3801,9 +3821,9 @@ effect. Long options that take arguments require a space between option
and argument. and argument.
@cindex options @cindex options
@table @code @table @gcctabopt
@item -D @var{name} @item -D @var{name}
Predefine @var{name} as a macro, with definition @samp{1}. Predefine @var{name} as a macro, with definition @code{1}.
@item -D @var{name}=@var{definition} @item -D @var{name}=@var{definition}
Predefine @var{name} as a macro, with definition @var{definition}. Predefine @var{name} as a macro, with definition @var{definition}.
...@@ -3818,7 +3838,7 @@ If you wish to define a function-like macro on the command line, write ...@@ -3818,7 +3838,7 @@ If you wish to define a function-like macro on the command line, write
its argument list with surrounding parentheses before the equals sign its argument list with surrounding parentheses before the equals sign
(if any). Parentheses are meaningful to most shells, so you will need (if any). Parentheses are meaningful to most shells, so you will need
to quote the option. With @command{sh} and @command{csh}, to quote the option. With @command{sh} and @command{csh},
@option{-D'@var{name}(@var{args...})=@var{definition}'} works. @option{-D'@var{name}(@var{args@dots{}})=@var{definition}'} works.
@item -U @var{name} @item -U @var{name}
Cancel any previous definition of @var{name}, either built in or Cancel any previous definition of @var{name}, either built in or
...@@ -3903,10 +3923,10 @@ without @samp{-pedantic} but treats as warnings. ...@@ -3903,10 +3923,10 @@ without @samp{-pedantic} but treats as warnings.
@item -M @item -M
Instead of outputting the result of preprocessing, output a rule Instead of outputting the result of preprocessing, output a rule
suitable for @code{make} describing the dependencies of the main source suitable for @command{make} describing the dependencies of the main
file. The preprocessor outputs one @code{make} rule containing the source file. The preprocessor outputs one @command{make} rule containing
object file name for that source file, a colon, and the names of all the the object file name for that source file, a colon, and the names of all
included files, including those coming from @option{-include} or the included files, including those coming from @option{-include} or
@option{-imacros} command line options. @option{-imacros} command line options.
Unless specified explicitly (with @option{-MT} or @option{-MQ}), the Unless specified explicitly (with @option{-MT} or @option{-MQ}), the
...@@ -3916,9 +3936,9 @@ files then the rule is split into several lines using @samp{\}-newline. ...@@ -3916,9 +3936,9 @@ files then the rule is split into several lines using @samp{\}-newline.
The rule has no commands. The rule has no commands.
@item -MM @item -MM
Like @option{-M}, but mention only the files included with @samp{#include Like @option{-M}, but mention only the files included with @code{@w{#include
"@var{file}"} or with @option{-include} or @option{-imacros} command line "@var{file}"}} or with @option{-include} or @option{-imacros} command line
options. System header files included with @samp{#include <@var{file}>} options. System header files included with @code{@w{#include <@var{file}>}}
are omitted. are omitted.
@item -MF @var{file} @item -MF @var{file}
...@@ -3938,8 +3958,8 @@ This feature is used in automatic updating of makefiles. ...@@ -3938,8 +3958,8 @@ This feature is used in automatic updating of makefiles.
@item -MP @item -MP
This option instructs CPP to add a phony target for each dependency This option instructs CPP to add a phony target for each dependency
other than the main file, causing each to depend on nothing. These other than the main file, causing each to depend on nothing. These
dummy rules work around errors @code{make} gives if you remove header dummy rules work around errors @command{make} gives if you remove header
files without updating the @code{Makefile} to match. files without updating the @file{Makefile} to match.
This is typical output: This is typical output:
...@@ -3960,7 +3980,7 @@ An @option{-MT} option will set the target to be exactly the string you ...@@ -3960,7 +3980,7 @@ An @option{-MT} option will set the target to be exactly the string you
specify. If you want multiple targets, you can specify them as a single specify. If you want multiple targets, you can specify them as a single
argument to @option{-MT}, or use multiple @option{-MT} options. argument to @option{-MT}, or use multiple @option{-MT} options.
For example, @samp{@w{-MT '$(objpfx)foo.o'}} might give For example, @option{@w{-MT '$(objpfx)foo.o'}} might give
@example @example
$(objpfx)foo.o: foo.c $(objpfx)foo.o: foo.c
...@@ -3969,7 +3989,7 @@ $(objpfx)foo.o: foo.c ...@@ -3969,7 +3989,7 @@ $(objpfx)foo.o: foo.c
@item -MQ @var{target} @item -MQ @var{target}
Same as @option{-MT}, but it quotes any characters which are special to Same as @option{-MT}, but it quotes any characters which are special to
Make. @samp{@w{-MQ '$(objpfx)foo.o'}} gives Make. @option{@w{-MQ '$(objpfx)foo.o'}} gives
@example @example
$$(objpfx)foo.o: foo.c $$(objpfx)foo.o: foo.c
...@@ -4042,13 +4062,13 @@ The 1999 C standard plus GNU extensions. ...@@ -4042,13 +4062,13 @@ The 1999 C standard plus GNU extensions.
@item -I- @item -I-
Split the include path. Any directories specified with @option{-I} Split the include path. Any directories specified with @option{-I}
options before @option{-I-} are searched only for headers requested with options before @option{-I-} are searched only for headers requested with
@samp{@w{#include "@var{file}"}}; they are not searched for @code{@w{#include "@var{file}"}}; they are not searched for
@samp{@w{#include <@var{file}>}}. If additional directories are @code{@w{#include <@var{file}>}}. If additional directories are
specified with @option{-I} options after the @option{-I-}, those specified with @option{-I} options after the @option{-I-}, those
directories are searched for all @samp{#include} directives. directories are searched for all @samp{#include} directives.
In addition, @option{-I-} inhibits the use of the directory of the current In addition, @option{-I-} inhibits the use of the directory of the current
file directory as the first search directory for @samp{@w{#include file directory as the first search directory for @code{@w{#include
"@var{file}"}}. @xref{Search Path}. "@var{file}"}}. @xref{Search Path}.
@item -nostdinc @item -nostdinc
...@@ -4067,7 +4087,7 @@ Process @var{file} as if @code{#include "file"} appeared as the first ...@@ -4067,7 +4087,7 @@ Process @var{file} as if @code{#include "file"} appeared as the first
line of the primary source file. However, the first directory searched line of the primary source file. However, the first directory searched
for @var{file} is the preprocessor's working directory @emph{instead of} for @var{file} is the preprocessor's working directory @emph{instead of}
the directory containing the main source file. If not found there, it the directory containing the main source file. If not found there, it
is searched for in the remainder of the @code{#include "..."} search is searched for in the remainder of the @code{#include "@dots{}"} search
chain as normal. chain as normal.
If multiple @option{-include} options are given, the files are included If multiple @option{-include} options are given, the files are included
...@@ -4116,7 +4136,7 @@ conversion, escaped newline splicing, and processing of most directives. ...@@ -4116,7 +4136,7 @@ conversion, escaped newline splicing, and processing of most directives.
In this mode the integrated preprocessor is little more than a tokenizer In this mode the integrated preprocessor is little more than a tokenizer
for the front ends. for the front ends.
@samp{-fpreprocessed} is implicit if the input file has one of the @option{-fpreprocessed} is implicit if the input file has one of the
extensions @samp{.i}, @samp{.ii} or @samp{.mi}. These are the extensions @samp{.i}, @samp{.ii} or @samp{.mi}. These are the
extensions that GCC uses for preprocessed files created by extensions that GCC uses for preprocessed files created by
@option{-save-temps}. @option{-save-temps}.
...@@ -4130,7 +4150,7 @@ ignored. The default is 8. ...@@ -4130,7 +4150,7 @@ ignored. The default is 8.
@item -fno-show-column @item -fno-show-column
Do not print column numbers in diagnostics. This may be necessary if Do not print column numbers in diagnostics. This may be necessary if
diagnostics are being scanned by a program that does not understand the diagnostics are being scanned by a program that does not understand the
column numbers, such as @code{dejagnu}. column numbers, such as @command{dejagnu}.
@item -A @var{predicate}=@var{answer} @item -A @var{predicate}=@var{answer}
Make an assertion with the predicate @var{predicate} and answer Make an assertion with the predicate @var{predicate} and answer
...@@ -4153,7 +4173,7 @@ Instead of the normal output, generate a list of @samp{#define} ...@@ -4153,7 +4173,7 @@ Instead of the normal output, generate a list of @samp{#define}
directives for all the macros defined during the execution of the directives for all the macros defined during the execution of the
preprocessor, including predefined macros. This gives you a way of preprocessor, including predefined macros. This gives you a way of
finding out what is predefined in your version of the preprocessor. finding out what is predefined in your version of the preprocessor.
Assuming you have no file @samp{foo.h}, the command Assuming you have no file @file{foo.h}, the command
@example @example
touch foo.h; cpp -dM foo.h touch foo.h; cpp -dM foo.h
...@@ -4199,7 +4219,8 @@ source line, since the first token on the line is no longer a @samp{#}. ...@@ -4199,7 +4219,8 @@ source line, since the first token on the line is no longer a @samp{#}.
@item -gcc @item -gcc
Define the macros @sc{__gnuc__}, @sc{__gnuc_minor__} and Define the macros @sc{__gnuc__}, @sc{__gnuc_minor__} and
@sc{__gnuc_patchlevel__}. These are defined automatically when you use @sc{__gnuc_patchlevel__}. These are defined automatically when you use
@samp{gcc -E}; you can turn them off in that case with @option{-no-gcc}. @command{gcc -E}; you can turn them off in that case with
@option{-no-gcc}.
@item -traditional @item -traditional
Try to imitate the behavior of old-fashioned C, as opposed to ISO Try to imitate the behavior of old-fashioned C, as opposed to ISO
...@@ -4215,8 +4236,7 @@ short file names, such as MS-DOS. ...@@ -4215,8 +4236,7 @@ short file names, such as MS-DOS.
@item -$ @item -$
Forbid the use of @samp{$} in identifiers. The C standard allows Forbid the use of @samp{$} in identifiers. The C standard allows
implementations to define extra characters that can appear in implementations to define extra characters that can appear in
identifiers. By default the GNU C preprocessor permits @samp{$}, a identifiers. By default GNU CPP permits @samp{$}, a common extension.
common extension.
@item -h @item -h
@itemx --help @itemx --help
......
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