| .\" Automatically generated by Pod::Man 2.16 (Pod::Simple 3.05) |
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| .\" ======================================================================== |
| .\" |
| .IX Title "CPP 1" |
| .TH CPP 1 "2015-12-04" "gcc-5.3.0" "GNU" |
| .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
| .\" way too many mistakes in technical documents. |
| .if n .ad l |
| .nh |
| .SH "NAME" |
| cpp \- The C Preprocessor |
| .SH "SYNOPSIS" |
| .IX Header "SYNOPSIS" |
| cpp [\fB\-D\fR\fImacro\fR[=\fIdefn\fR]...] [\fB\-U\fR\fImacro\fR] |
| [\fB\-I\fR\fIdir\fR...] [\fB\-iquote\fR\fIdir\fR...] |
| [\fB\-W\fR\fIwarn\fR...] |
| [\fB\-M\fR|\fB\-MM\fR] [\fB\-MG\fR] [\fB\-MF\fR \fIfilename\fR] |
| [\fB\-MP\fR] [\fB\-MQ\fR \fItarget\fR...] |
| [\fB\-MT\fR \fItarget\fR...] |
| [\fB\-P\fR] [\fB\-fno\-working\-directory\fR] |
| [\fB\-x\fR \fIlanguage\fR] [\fB\-std=\fR\fIstandard\fR] |
| \fIinfile\fR \fIoutfile\fR |
| .PP |
| Only the most useful options are listed here; see below for the remainder. |
| .SH "DESCRIPTION" |
| .IX Header "DESCRIPTION" |
| The C preprocessor, often known as \fIcpp\fR, is a \fImacro processor\fR |
| that is used automatically by the C compiler to transform your program |
| before compilation. It is called a macro processor because it allows |
| you to define \fImacros\fR, which are brief abbreviations for longer |
| constructs. |
| .PP |
| The C preprocessor is intended to be used only with C, \*(C+, and |
| Objective-C source code. In the past, it has been abused as a general |
| text processor. It will choke on input which does not obey C's lexical |
| rules. For example, apostrophes will be interpreted as the beginning of |
| character constants, and cause errors. Also, you cannot rely on it |
| preserving characteristics of the input which are not significant to |
| C\-family languages. If a Makefile is preprocessed, all the hard tabs |
| will be removed, and the Makefile will not work. |
| .PP |
| Having said that, you can often get away with using cpp on things which |
| are not C. Other Algol-ish programming languages are often safe |
| (Pascal, Ada, etc.) So is assembly, with caution. \fB\-traditional\-cpp\fR |
| mode preserves more white space, and is otherwise more permissive. Many |
| of the problems can be avoided by writing C or \*(C+ style comments |
| instead of native language comments, and keeping macros simple. |
| .PP |
| 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 |
| facilities. Most high level programming languages have their own |
| conditional compilation and inclusion mechanism. If all else fails, |
| try a true general text processor, such as \s-1GNU\s0 M4. |
| .PP |
| 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 |
| Standard C. In its default mode, the \s-1GNU\s0 C preprocessor does not do a |
| few things required by the standard. These are features which are |
| rarely, if ever, used, and may cause surprising changes to the meaning |
| of a program which does not expect them. To get strict \s-1ISO\s0 Standard C, |
| you should use the \fB\-std=c90\fR, \fB\-std=c99\fR or |
| \&\fB\-std=c11\fR options, depending |
| on which version of the standard you want. To get all the mandatory |
| diagnostics, you must also use \fB\-pedantic\fR. |
| .PP |
| This manual describes the behavior of the \s-1ISO\s0 preprocessor. To |
| minimize gratuitous differences, where the \s-1ISO\s0 preprocessor's |
| behavior does not conflict with traditional semantics, the |
| traditional preprocessor should behave the same way. The various |
| differences that do exist are detailed in the section \fBTraditional |
| Mode\fR. |
| .PP |
| For clarity, unless noted otherwise, references to \fB\s-1CPP\s0\fR in this |
| manual refer to \s-1GNU\s0 \s-1CPP\s0. |
| .SH "OPTIONS" |
| .IX Header "OPTIONS" |
| The C preprocessor expects two file names as arguments, \fIinfile\fR and |
| \&\fIoutfile\fR. The preprocessor reads \fIinfile\fR together with any |
| other files it specifies with \fB#include\fR. All the output generated |
| by the combined input files is written in \fIoutfile\fR. |
| .PP |
| Either \fIinfile\fR or \fIoutfile\fR may be \fB\-\fR, which as |
| \&\fIinfile\fR means to read from standard input and as \fIoutfile\fR |
| means to write to standard output. Also, if either file is omitted, it |
| means the same as if \fB\-\fR had been specified for that file. |
| .PP |
| Unless otherwise noted, or the option ends in \fB=\fR, all options |
| which take an argument may have that argument appear either immediately |
| after the option, or with a space between option and argument: |
| \&\fB\-Ifoo\fR and \fB\-I foo\fR have the same effect. |
| .PP |
| Many options have multi-letter names; therefore multiple single-letter |
| options may \fInot\fR be grouped: \fB\-dM\fR is very different from |
| \&\fB\-d\ \-M\fR. |
| .IP "\fB\-D\fR \fIname\fR" 4 |
| .IX Item "-D name" |
| Predefine \fIname\fR as a macro, with definition \f(CW1\fR. |
| .IP "\fB\-D\fR \fIname\fR\fB=\fR\fIdefinition\fR" 4 |
| .IX Item "-D name=definition" |
| The contents of \fIdefinition\fR are tokenized and processed as if |
| they appeared during translation phase three in a \fB#define\fR |
| directive. In particular, the definition will be truncated by |
| embedded newline characters. |
| .Sp |
| If you are invoking the preprocessor from a shell or shell-like |
| program you may need to use the shell's quoting syntax to protect |
| characters such as spaces that have a meaning in the shell syntax. |
| .Sp |
| If you wish to define a function-like macro on the command line, write |
| its argument list with surrounding parentheses before the equals sign |
| (if any). Parentheses are meaningful to most shells, so you will need |
| 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. |
| .Sp |
| \&\fB\-D\fR and \fB\-U\fR options are processed in the order they |
| are given on the command line. 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. |
| .IP "\fB\-U\fR \fIname\fR" 4 |
| .IX Item "-U name" |
| Cancel any previous definition of \fIname\fR, either built in or |
| provided with a \fB\-D\fR option. |
| .IP "\fB\-undef\fR" 4 |
| .IX Item "-undef" |
| Do not predefine any system-specific or GCC-specific macros. The |
| standard predefined macros remain defined. |
| .IP "\fB\-I\fR \fIdir\fR" 4 |
| .IX Item "-I dir" |
| Add the directory \fIdir\fR to the list of directories to be searched |
| for header files. |
| .Sp |
| Directories named by \fB\-I\fR are searched before the standard |
| system include directories. If the directory \fIdir\fR is a standard |
| system include directory, the option is ignored to ensure that the |
| default search order for system directories and the special treatment |
| of system headers are not defeated |
| \&. |
| If \fIdir\fR begins with \f(CW\*(C`=\*(C'\fR, then the \f(CW\*(C`=\*(C'\fR will be replaced |
| by the sysroot prefix; see \fB\-\-sysroot\fR and \fB\-isysroot\fR. |
| .IP "\fB\-o\fR \fIfile\fR" 4 |
| .IX Item "-o file" |
| 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 |
| different interpretation of a second non-option argument, so you must |
| use \fB\-o\fR to specify the output file. |
| .IP "\fB\-Wall\fR" 4 |
| .IX Item "-Wall" |
| Turns on all optional warnings which are desirable for normal code. |
| At present this is \fB\-Wcomment\fR, \fB\-Wtrigraphs\fR, |
| \&\fB\-Wmultichar\fR and a warning about integer promotion causing a |
| change of sign in \f(CW\*(C`#if\*(C'\fR expressions. Note that many of the |
| preprocessor's warnings are on by default and have no options to |
| control them. |
| .IP "\fB\-Wcomment\fR" 4 |
| .IX Item "-Wcomment" |
| .PD 0 |
| .IP "\fB\-Wcomments\fR" 4 |
| .IX Item "-Wcomments" |
| .PD |
| 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. |
| (Both forms have the same effect.) |
| .IP "\fB\-Wtrigraphs\fR" 4 |
| .IX Item "-Wtrigraphs" |
| Most trigraphs in comments cannot affect the meaning of the program. |
| However, a trigraph that would form an escaped newline (\fB??/\fR at |
| the end of a line) can, by changing where the comment begins or ends. |
| Therefore, only trigraphs that would form escaped newlines produce |
| warnings inside a comment. |
| .Sp |
| This option is implied by \fB\-Wall\fR. If \fB\-Wall\fR is not |
| given, this option is still enabled unless trigraphs are enabled. To |
| get trigraph conversion without warnings, but get the other |
| \&\fB\-Wall\fR warnings, use \fB\-trigraphs \-Wall \-Wno\-trigraphs\fR. |
| .IP "\fB\-Wtraditional\fR" 4 |
| .IX Item "-Wtraditional" |
| 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 |
| equivalent, and problematic constructs which should be avoided. |
| .IP "\fB\-Wundef\fR" 4 |
| .IX Item "-Wundef" |
| Warn whenever an identifier which is not a macro is encountered in an |
| \&\fB#if\fR directive, outside of \fBdefined\fR. Such identifiers are |
| replaced with zero. |
| .IP "\fB\-Wunused\-macros\fR" 4 |
| .IX Item "-Wunused-macros" |
| Warn about macros defined in the main file that are unused. A macro |
| is \fIused\fR if it is expanded or tested for existence at least once. |
| The preprocessor will also warn if the macro has not been used at the |
| time it is redefined or undefined. |
| .Sp |
| Built-in macros, macros defined on the command line, and macros |
| defined in include files are not warned about. |
| .Sp |
| \&\fINote:\fR If a macro is actually used, but only used in skipped |
| conditional blocks, then \s-1CPP\s0 will report it as unused. To avoid the |
| warning in such a case, you might improve the scope of the macro's |
| definition by, for example, moving it into the first skipped block. |
| Alternatively, you could provide a dummy use with something like: |
| .Sp |
| .Vb 2 |
| \& #if defined the_macro_causing_the_warning |
| \& #endif |
| .Ve |
| .IP "\fB\-Wendif\-labels\fR" 4 |
| .IX Item "-Wendif-labels" |
| Warn whenever an \fB#else\fR or an \fB#endif\fR are followed by text. |
| This usually happens in code of the form |
| .Sp |
| .Vb 5 |
| \& #if FOO |
| \& ... |
| \& #else FOO |
| \& ... |
| \& #endif FOO |
| .Ve |
| .Sp |
| The second and third \f(CW\*(C`FOO\*(C'\fR should be in comments, but often are not |
| in older programs. This warning is on by default. |
| .IP "\fB\-Werror\fR" 4 |
| .IX Item "-Werror" |
| Make all warnings into hard errors. Source code which triggers warnings |
| will be rejected. |
| .IP "\fB\-Wsystem\-headers\fR" 4 |
| .IX Item "-Wsystem-headers" |
| Issue warnings for code in system headers. These are normally unhelpful |
| in finding bugs in your own code, therefore suppressed. If you are |
| responsible for the system library, you may want to see them. |
| .IP "\fB\-w\fR" 4 |
| .IX Item "-w" |
| Suppress all warnings, including those which \s-1GNU\s0 \s-1CPP\s0 issues by default. |
| .IP "\fB\-pedantic\fR" 4 |
| .IX Item "-pedantic" |
| Issue all the mandatory diagnostics listed in the C standard. Some of |
| them are left out by default, since they trigger frequently on harmless |
| code. |
| .IP "\fB\-pedantic\-errors\fR" 4 |
| .IX Item "-pedantic-errors" |
| Issue all the mandatory diagnostics, and make all mandatory diagnostics |
| into errors. This includes mandatory diagnostics that \s-1GCC\s0 issues |
| without \fB\-pedantic\fR but treats as warnings. |
| .IP "\fB\-M\fR" 4 |
| .IX Item "-M" |
| Instead of outputting the result of preprocessing, output a rule |
| suitable for \fBmake\fR describing the dependencies of the main |
| source file. The preprocessor outputs one \fBmake\fR rule containing |
| the object file name for that source file, a colon, and the names of all |
| the included files, including those coming from \fB\-include\fR or |
| \&\fB\-imacros\fR command-line options. |
| .Sp |
| Unless specified explicitly (with \fB\-MT\fR or \fB\-MQ\fR), the |
| object file name consists of the name of the source file with any |
| suffix replaced with object file suffix and with any leading directory |
| parts removed. If there are many included files then the rule is |
| split into several lines using \fB\e\fR\-newline. The rule has no |
| commands. |
| .Sp |
| This option does not suppress the preprocessor's debug output, such as |
| \&\fB\-dM\fR. To avoid mixing such debug output with the dependency |
| rules you should explicitly specify the dependency output file with |
| \&\fB\-MF\fR, or use an environment variable like |
| \&\fB\s-1DEPENDENCIES_OUTPUT\s0\fR. Debug output |
| will still be sent to the regular output stream as normal. |
| .Sp |
| Passing \fB\-M\fR to the driver implies \fB\-E\fR, and suppresses |
| warnings with an implicit \fB\-w\fR. |
| .IP "\fB\-MM\fR" 4 |
| .IX Item "-MM" |
| Like \fB\-M\fR but do not mention header files that are found in |
| system header directories, nor header files that are included, |
| directly or indirectly, from such a header. |
| .Sp |
| This implies that the choice of angle brackets or double quotes in an |
| \&\fB#include\fR directive does not in itself determine whether that |
| header will appear in \fB\-MM\fR dependency output. This is a |
| slight change in semantics from \s-1GCC\s0 versions 3.0 and earlier. |
| .IP "\fB\-MF\fR \fIfile\fR" 4 |
| .IX Item "-MF file" |
| When used with \fB\-M\fR or \fB\-MM\fR, specifies a |
| file to write the dependencies to. If no \fB\-MF\fR switch is given |
| the preprocessor sends the rules to the same place it would have sent |
| preprocessed output. |
| .Sp |
| When used with the driver options \fB\-MD\fR or \fB\-MMD\fR, |
| \&\fB\-MF\fR overrides the default dependency output file. |
| .IP "\fB\-MG\fR" 4 |
| .IX Item "-MG" |
| In conjunction with an option such as \fB\-M\fR requesting |
| dependency generation, \fB\-MG\fR assumes missing header files are |
| generated files and adds them to the dependency list without raising |
| an error. The dependency filename is taken directly from the |
| \&\f(CW\*(C`#include\*(C'\fR directive without prepending any path. \fB\-MG\fR |
| also suppresses preprocessed output, as a missing header file renders |
| this useless. |
| .Sp |
| This feature is used in automatic updating of makefiles. |
| .IP "\fB\-MP\fR" 4 |
| .IX Item "-MP" |
| 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 |
| dummy rules work around errors \fBmake\fR gives if you remove header |
| files without updating the \fIMakefile\fR to match. |
| .Sp |
| This is typical output: |
| .Sp |
| .Vb 1 |
| \& test.o: test.c test.h |
| \& |
| \& test.h: |
| .Ve |
| .IP "\fB\-MT\fR \fItarget\fR" 4 |
| .IX Item "-MT target" |
| Change the target of the rule emitted by dependency generation. By |
| default \s-1CPP\s0 takes the name of the main input file, deletes any |
| directory components and any file suffix such as \fB.c\fR, and |
| appends the platform's usual object suffix. The result is the target. |
| .Sp |
| An \fB\-MT\fR option will set the target to be exactly the string you |
| specify. If you want multiple targets, you can specify them as a single |
| argument to \fB\-MT\fR, or use multiple \fB\-MT\fR options. |
| .Sp |
| For example, \fB\-MT\ '$(objpfx)foo.o'\fR might give |
| .Sp |
| .Vb 1 |
| \& $(objpfx)foo.o: foo.c |
| .Ve |
| .IP "\fB\-MQ\fR \fItarget\fR" 4 |
| .IX Item "-MQ target" |
| Same as \fB\-MT\fR, but it quotes any characters which are special to |
| Make. \fB\-MQ\ '$(objpfx)foo.o'\fR gives |
| .Sp |
| .Vb 1 |
| \& $$(objpfx)foo.o: foo.c |
| .Ve |
| .Sp |
| The default target is automatically quoted, as if it were given with |
| \&\fB\-MQ\fR. |
| .IP "\fB\-MD\fR" 4 |
| .IX Item "-MD" |
| \&\fB\-MD\fR is equivalent to \fB\-M \-MF\fR \fIfile\fR, except that |
| \&\fB\-E\fR is not implied. The driver determines \fIfile\fR based on |
| whether an \fB\-o\fR option is given. If it is, the driver uses its |
| argument but with a suffix of \fI.d\fR, otherwise it takes the name |
| of the input file, removes any directory components and suffix, and |
| applies a \fI.d\fR suffix. |
| .Sp |
| If \fB\-MD\fR is used in conjunction with \fB\-E\fR, any |
| \&\fB\-o\fR switch is understood to specify the dependency output file, but if used without \fB\-E\fR, each \fB\-o\fR |
| is understood to specify a target object file. |
| .Sp |
| Since \fB\-E\fR is not implied, \fB\-MD\fR can be used to generate |
| a dependency output file as a side-effect of the compilation process. |
| .IP "\fB\-MMD\fR" 4 |
| .IX Item "-MMD" |
| Like \fB\-MD\fR except mention only user header files, not system |
| header files. |
| .IP "\fB\-x c\fR" 4 |
| .IX Item "-x c" |
| .PD 0 |
| .IP "\fB\-x c++\fR" 4 |
| .IX Item "-x c++" |
| .IP "\fB\-x objective-c\fR" 4 |
| .IX Item "-x objective-c" |
| .IP "\fB\-x assembler-with-cpp\fR" 4 |
| .IX Item "-x assembler-with-cpp" |
| .PD |
| Specify the source language: C, \*(C+, Objective-C, or assembly. This has |
| nothing to do with standards conformance or extensions; it merely |
| selects which base syntax to expect. If you give none of these options, |
| cpp will deduce the language from the extension of the source file: |
| \&\fB.c\fR, \fB.cc\fR, \fB.m\fR, or \fB.S\fR. Some other common |
| extensions for \*(C+ and assembly are also recognized. If cpp does not |
| recognize the extension, it will treat the file as C; this is the most |
| generic mode. |
| .Sp |
| \&\fINote:\fR Previous versions of cpp accepted a \fB\-lang\fR option |
| which selected both the language and the standards conformance level. |
| This option has been removed, because it conflicts with the \fB\-l\fR |
| option. |
| .IP "\fB\-std=\fR\fIstandard\fR" 4 |
| .IX Item "-std=standard" |
| .PD 0 |
| .IP "\fB\-ansi\fR" 4 |
| .IX Item "-ansi" |
| .PD |
| Specify the standard to which the code should conform. Currently \s-1CPP\s0 |
| knows about C and \*(C+ standards; others may be added in the future. |
| .Sp |
| \&\fIstandard\fR |
| may be one of: |
| .RS 4 |
| .ie n .IP """c90""" 4 |
| .el .IP "\f(CWc90\fR" 4 |
| .IX Item "c90" |
| .PD 0 |
| .ie n .IP """c89""" 4 |
| .el .IP "\f(CWc89\fR" 4 |
| .IX Item "c89" |
| .ie n .IP """iso9899:1990""" 4 |
| .el .IP "\f(CWiso9899:1990\fR" 4 |
| .IX Item "iso9899:1990" |
| .PD |
| The \s-1ISO\s0 C standard from 1990. \fBc90\fR is the customary shorthand for |
| this version of the standard. |
| .Sp |
| The \fB\-ansi\fR option is equivalent to \fB\-std=c90\fR. |
| .ie n .IP """iso9899:199409""" 4 |
| .el .IP "\f(CWiso9899:199409\fR" 4 |
| .IX Item "iso9899:199409" |
| The 1990 C standard, as amended in 1994. |
| .ie n .IP """iso9899:1999""" 4 |
| .el .IP "\f(CWiso9899:1999\fR" 4 |
| .IX Item "iso9899:1999" |
| .PD 0 |
| .ie n .IP """c99""" 4 |
| .el .IP "\f(CWc99\fR" 4 |
| .IX Item "c99" |
| .ie n .IP """iso9899:199x""" 4 |
| .el .IP "\f(CWiso9899:199x\fR" 4 |
| .IX Item "iso9899:199x" |
| .ie n .IP """c9x""" 4 |
| .el .IP "\f(CWc9x\fR" 4 |
| .IX Item "c9x" |
| .PD |
| The revised \s-1ISO\s0 C standard, published in December 1999. Before |
| publication, this was known as C9X. |
| .ie n .IP """iso9899:2011""" 4 |
| .el .IP "\f(CWiso9899:2011\fR" 4 |
| .IX Item "iso9899:2011" |
| .PD 0 |
| .ie n .IP """c11""" 4 |
| .el .IP "\f(CWc11\fR" 4 |
| .IX Item "c11" |
| .ie n .IP """c1x""" 4 |
| .el .IP "\f(CWc1x\fR" 4 |
| .IX Item "c1x" |
| .PD |
| The revised \s-1ISO\s0 C standard, published in December 2011. Before |
| publication, this was known as C1X. |
| .ie n .IP """gnu90""" 4 |
| .el .IP "\f(CWgnu90\fR" 4 |
| .IX Item "gnu90" |
| .PD 0 |
| .ie n .IP """gnu89""" 4 |
| .el .IP "\f(CWgnu89\fR" 4 |
| .IX Item "gnu89" |
| .PD |
| The 1990 C standard plus \s-1GNU\s0 extensions. This is the default. |
| .ie n .IP """gnu99""" 4 |
| .el .IP "\f(CWgnu99\fR" 4 |
| .IX Item "gnu99" |
| .PD 0 |
| .ie n .IP """gnu9x""" 4 |
| .el .IP "\f(CWgnu9x\fR" 4 |
| .IX Item "gnu9x" |
| .PD |
| The 1999 C standard plus \s-1GNU\s0 extensions. |
| .ie n .IP """gnu11""" 4 |
| .el .IP "\f(CWgnu11\fR" 4 |
| .IX Item "gnu11" |
| .PD 0 |
| .ie n .IP """gnu1x""" 4 |
| .el .IP "\f(CWgnu1x\fR" 4 |
| .IX Item "gnu1x" |
| .PD |
| The 2011 C standard plus \s-1GNU\s0 extensions. |
| .ie n .IP """c++98""" 4 |
| .el .IP "\f(CWc++98\fR" 4 |
| .IX Item "c++98" |
| The 1998 \s-1ISO\s0 \*(C+ standard plus amendments. |
| .ie n .IP """gnu++98""" 4 |
| .el .IP "\f(CWgnu++98\fR" 4 |
| .IX Item "gnu++98" |
| The same as \fB\-std=c++98\fR plus \s-1GNU\s0 extensions. This is the |
| default for \*(C+ code. |
| .RE |
| .RS 4 |
| .RE |
| .IP "\fB\-I\-\fR" 4 |
| .IX Item "-I-" |
| Split the include path. Any directories specified with \fB\-I\fR |
| options before \fB\-I\-\fR are searched only for headers requested with |
| \&\f(CW\*(C`#include\ "\f(CIfile\f(CW"\*(C'\fR; they are not searched for |
| \&\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 |
| directories are searched for all \fB#include\fR directives. |
| .Sp |
| In addition, \fB\-I\-\fR inhibits the use of the directory of the current |
| file directory as the first search directory for \f(CW\*(C`#include\ "\f(CIfile\f(CW"\*(C'\fR. |
| .Sp |
| This option has been deprecated. |
| .IP "\fB\-nostdinc\fR" 4 |
| .IX Item "-nostdinc" |
| Do not search the standard system directories for header files. |
| Only the directories you have specified with \fB\-I\fR options |
| (and the directory of the current file, if appropriate) are searched. |
| .IP "\fB\-nostdinc++\fR" 4 |
| .IX Item "-nostdinc++" |
| Do not search for header files in the \*(C+\-specific standard directories, |
| but do still search the other standard directories. (This option is |
| used when building the \*(C+ library.) |
| .IP "\fB\-include\fR \fIfile\fR" 4 |
| .IX Item "-include file" |
| 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 |
| for \fIfile\fR is the preprocessor's working directory \fIinstead of\fR |
| the directory containing the main source file. If not found there, it |
| is searched for in the remainder of the \f(CW\*(C`#include "..."\*(C'\fR search |
| chain as normal. |
| .Sp |
| If multiple \fB\-include\fR options are given, the files are included |
| in the order they appear on the command line. |
| .IP "\fB\-imacros\fR \fIfile\fR" 4 |
| .IX Item "-imacros file" |
| Exactly like \fB\-include\fR, except that any output produced by |
| scanning \fIfile\fR is thrown away. Macros it defines remain defined. |
| This allows you to acquire all the macros from a header without also |
| processing its declarations. |
| .Sp |
| All files specified by \fB\-imacros\fR are processed before all files |
| specified by \fB\-include\fR. |
| .IP "\fB\-idirafter\fR \fIdir\fR" 4 |
| .IX Item "-idirafter dir" |
| Search \fIdir\fR for header files, but do it \fIafter\fR all |
| directories specified with \fB\-I\fR and the standard system directories |
| have been exhausted. \fIdir\fR is treated as a system include directory. |
| If \fIdir\fR begins with \f(CW\*(C`=\*(C'\fR, then the \f(CW\*(C`=\*(C'\fR will be replaced |
| by the sysroot prefix; see \fB\-\-sysroot\fR and \fB\-isysroot\fR. |
| .IP "\fB\-iprefix\fR \fIprefix\fR" 4 |
| .IX Item "-iprefix prefix" |
| Specify \fIprefix\fR as the prefix for subsequent \fB\-iwithprefix\fR |
| options. If the prefix represents a directory, you should include the |
| final \fB/\fR. |
| .IP "\fB\-iwithprefix\fR \fIdir\fR" 4 |
| .IX Item "-iwithprefix dir" |
| .PD 0 |
| .IP "\fB\-iwithprefixbefore\fR \fIdir\fR" 4 |
| .IX Item "-iwithprefixbefore dir" |
| .PD |
| Append \fIdir\fR to the prefix specified previously with |
| \&\fB\-iprefix\fR, and add the resulting directory to the include search |
| path. \fB\-iwithprefixbefore\fR puts it in the same place \fB\-I\fR |
| would; \fB\-iwithprefix\fR puts it where \fB\-idirafter\fR would. |
| .IP "\fB\-isysroot\fR \fIdir\fR" 4 |
| .IX Item "-isysroot dir" |
| This option is like the \fB\-\-sysroot\fR option, but applies only to |
| header files (except for Darwin targets, where it applies to both header |
| files and libraries). See the \fB\-\-sysroot\fR option for more |
| information. |
| .IP "\fB\-imultilib\fR \fIdir\fR" 4 |
| .IX Item "-imultilib dir" |
| Use \fIdir\fR as a subdirectory of the directory containing |
| target-specific \*(C+ headers. |
| .IP "\fB\-isystem\fR \fIdir\fR" 4 |
| .IX Item "-isystem dir" |
| Search \fIdir\fR for header files, after all directories specified by |
| \&\fB\-I\fR but before the standard system directories. Mark it |
| as a system directory, so that it gets the same special treatment as |
| is applied to the standard system directories. |
| .Sp |
| If \fIdir\fR begins with \f(CW\*(C`=\*(C'\fR, then the \f(CW\*(C`=\*(C'\fR will be replaced |
| by the sysroot prefix; see \fB\-\-sysroot\fR and \fB\-isysroot\fR. |
| .IP "\fB\-iquote\fR \fIdir\fR" 4 |
| .IX Item "-iquote dir" |
| Search \fIdir\fR only for header files requested with |
| \&\f(CW\*(C`#include\ "\f(CIfile\f(CW"\*(C'\fR; they are not searched for |
| \&\f(CW\*(C`#include\ <\f(CIfile\f(CW>\*(C'\fR, before all directories specified by |
| \&\fB\-I\fR and before the standard system directories. |
| .Sp |
| If \fIdir\fR begins with \f(CW\*(C`=\*(C'\fR, then the \f(CW\*(C`=\*(C'\fR will be replaced |
| by the sysroot prefix; see \fB\-\-sysroot\fR and \fB\-isysroot\fR. |
| .IP "\fB\-fdirectives\-only\fR" 4 |
| .IX Item "-fdirectives-only" |
| When preprocessing, handle directives, but do not expand macros. |
| .Sp |
| The option's behavior depends on the \fB\-E\fR and \fB\-fpreprocessed\fR |
| options. |
| .Sp |
| With \fB\-E\fR, preprocessing is limited to the handling of directives |
| such as \f(CW\*(C`#define\*(C'\fR, \f(CW\*(C`#ifdef\*(C'\fR, and \f(CW\*(C`#error\*(C'\fR. Other |
| preprocessor operations, such as macro expansion and trigraph |
| conversion are not performed. In addition, the \fB\-dD\fR option is |
| implicitly enabled. |
| .Sp |
| With \fB\-fpreprocessed\fR, predefinition of command line and most |
| builtin macros is disabled. Macros such as \f(CW\*(C`_\|_LINE_\|_\*(C'\fR, which are |
| contextually dependent, are handled normally. This enables compilation of |
| files previously preprocessed with \f(CW\*(C`\-E \-fdirectives\-only\*(C'\fR. |
| .Sp |
| With both \fB\-E\fR and \fB\-fpreprocessed\fR, the rules for |
| \&\fB\-fpreprocessed\fR take precedence. This enables full preprocessing of |
| files previously preprocessed with \f(CW\*(C`\-E \-fdirectives\-only\*(C'\fR. |
| .IP "\fB\-fdollars\-in\-identifiers\fR" 4 |
| .IX Item "-fdollars-in-identifiers" |
| Accept \fB$\fR in identifiers. |
| .IP "\fB\-fextended\-identifiers\fR" 4 |
| .IX Item "-fextended-identifiers" |
| Accept universal character names in identifiers. This option is |
| enabled by default for C99 (and later C standard versions) and \*(C+. |
| .IP "\fB\-fno\-canonical\-system\-headers\fR" 4 |
| .IX Item "-fno-canonical-system-headers" |
| When preprocessing, do not shorten system header paths with canonicalization. |
| .IP "\fB\-fpreprocessed\fR" 4 |
| .IX Item "-fpreprocessed" |
| Indicate to the preprocessor that the input file has already been |
| preprocessed. This suppresses things like macro expansion, trigraph |
| conversion, escaped newline splicing, and processing of most directives. |
| The preprocessor still recognizes and removes comments, so that you can |
| pass a file preprocessed with \fB\-C\fR to the compiler without |
| problems. In this mode the integrated preprocessor is little more than |
| a tokenizer for the front ends. |
| .Sp |
| \&\fB\-fpreprocessed\fR is implicit if the input file has one of 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 |
| \&\fB\-save\-temps\fR. |
| .IP "\fB\-ftabstop=\fR\fIwidth\fR" 4 |
| .IX Item "-ftabstop=width" |
| Set the distance between tab stops. This helps the preprocessor report |
| correct column numbers in warnings or errors, even if tabs appear on the |
| line. If the value is less than 1 or greater than 100, the option is |
| ignored. The default is 8. |
| .IP "\fB\-fdebug\-cpp\fR" 4 |
| .IX Item "-fdebug-cpp" |
| This option is only useful for debugging \s-1GCC\s0. When used with |
| \&\fB\-E\fR, dumps debugging information about location maps. Every |
| token in the output is preceded by the dump of the map its location |
| belongs to. The dump of the map holding the location of a token would |
| be: |
| .Sp |
| .Vb 1 |
| \& {"P":F</file/path>;"F":F</includer/path>;"L":<line_num>;"C":<col_num>;"S":<system_header_p>;"M":<map_address>;"E":<macro_expansion_p>,"loc":<location>} |
| .Ve |
| .Sp |
| When used without \fB\-E\fR, this option has no effect. |
| .IP "\fB\-ftrack\-macro\-expansion\fR[\fB=\fR\fIlevel\fR]" 4 |
| .IX Item "-ftrack-macro-expansion[=level]" |
| Track locations of tokens across macro expansions. This allows the |
| compiler to emit diagnostic about the current macro expansion stack |
| when a compilation error occurs in a macro expansion. Using this |
| option makes the preprocessor and the compiler consume more |
| memory. The \fIlevel\fR parameter can be used to choose the level of |
| precision of token location tracking thus decreasing the memory |
| consumption if necessary. Value \fB0\fR of \fIlevel\fR de-activates |
| this option just as if no \fB\-ftrack\-macro\-expansion\fR was present |
| on the command line. Value \fB1\fR tracks tokens locations in a |
| degraded mode for the sake of minimal memory overhead. In this mode |
| all tokens resulting from the expansion of an argument of a |
| function-like macro have the same location. Value \fB2\fR tracks |
| tokens locations completely. This value is the most memory hungry. |
| When this option is given no argument, the default parameter value is |
| \&\fB2\fR. |
| .Sp |
| Note that \f(CW\*(C`\-ftrack\-macro\-expansion=2\*(C'\fR is activated by default. |
| .IP "\fB\-fexec\-charset=\fR\fIcharset\fR" 4 |
| .IX Item "-fexec-charset=charset" |
| Set the execution character set, used for string and character |
| constants. The default is \s-1UTF\-8\s0. \fIcharset\fR can be any encoding |
| supported by the system's \f(CW\*(C`iconv\*(C'\fR library routine. |
| .IP "\fB\-fwide\-exec\-charset=\fR\fIcharset\fR" 4 |
| .IX Item "-fwide-exec-charset=charset" |
| Set the wide execution character set, used for wide string and |
| character constants. The default is \s-1UTF\-32\s0 or \s-1UTF\-16\s0, whichever |
| corresponds to the width of \f(CW\*(C`wchar_t\*(C'\fR. As with |
| \&\fB\-fexec\-charset\fR, \fIcharset\fR can be any encoding supported |
| by the system's \f(CW\*(C`iconv\*(C'\fR library routine; however, you will have |
| problems with encodings that do not fit exactly in \f(CW\*(C`wchar_t\*(C'\fR. |
| .IP "\fB\-finput\-charset=\fR\fIcharset\fR" 4 |
| .IX Item "-finput-charset=charset" |
| Set the input character set, used for translation from the character |
| set of the input file to the source character set used by \s-1GCC\s0. If the |
| locale does not specify, or \s-1GCC\s0 cannot get this information from the |
| locale, the default is \s-1UTF\-8\s0. This can be overridden by either the locale |
| or this command-line option. Currently the command-line option takes |
| precedence if there's a conflict. \fIcharset\fR can be any encoding |
| supported by the system's \f(CW\*(C`iconv\*(C'\fR library routine. |
| .IP "\fB\-fworking\-directory\fR" 4 |
| .IX Item "-fworking-directory" |
| Enable generation of linemarkers in the preprocessor output that will |
| let the compiler know the current working directory at the time of |
| preprocessing. When this option is enabled, the preprocessor will |
| emit, after the initial linemarker, a second linemarker with the |
| current working directory followed by two slashes. \s-1GCC\s0 will use this |
| directory, when it's present in the preprocessed input, as the |
| directory emitted as the current working directory in some debugging |
| information formats. This option is implicitly enabled if debugging |
| information is enabled, but this can be inhibited with the negated |
| form \fB\-fno\-working\-directory\fR. If the \fB\-P\fR flag is |
| present in the command line, this option has no effect, since no |
| \&\f(CW\*(C`#line\*(C'\fR directives are emitted whatsoever. |
| .IP "\fB\-fno\-show\-column\fR" 4 |
| .IX Item "-fno-show-column" |
| Do not print column numbers in diagnostics. This may be necessary if |
| diagnostics are being scanned by a program that does not understand the |
| column numbers, such as \fBdejagnu\fR. |
| .IP "\fB\-A\fR \fIpredicate\fR\fB=\fR\fIanswer\fR" 4 |
| .IX Item "-A predicate=answer" |
| Make an assertion with the predicate \fIpredicate\fR and answer |
| \&\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 |
| it does not use shell special characters. |
| .IP "\fB\-A \-\fR\fIpredicate\fR\fB=\fR\fIanswer\fR" 4 |
| .IX Item "-A -predicate=answer" |
| Cancel an assertion with the predicate \fIpredicate\fR and answer |
| \&\fIanswer\fR. |
| .IP "\fB\-dCHARS\fR" 4 |
| .IX Item "-dCHARS" |
| \&\fI\s-1CHARS\s0\fR is a sequence of one or more of the following characters, |
| and must not be preceded by a space. Other characters are interpreted |
| by the compiler proper, or reserved for future versions of \s-1GCC\s0, and so |
| are silently ignored. If you specify characters whose behavior |
| conflicts, the result is undefined. |
| .RS 4 |
| .IP "\fBM\fR" 4 |
| .IX Item "M" |
| Instead of the normal output, generate a list of \fB#define\fR |
| directives for all the macros defined during the execution of the |
| preprocessor, including predefined macros. This gives you a way of |
| finding out what is predefined in your version of the preprocessor. |
| Assuming you have no file \fIfoo.h\fR, the command |
| .Sp |
| .Vb 1 |
| \& touch foo.h; cpp \-dM foo.h |
| .Ve |
| .Sp |
| will show all the predefined macros. |
| .Sp |
| If you use \fB\-dM\fR without the \fB\-E\fR option, \fB\-dM\fR is |
| interpreted as a synonym for \fB\-fdump\-rtl\-mach\fR. |
| .IP "\fBD\fR" 4 |
| .IX Item "D" |
| Like \fBM\fR except in two respects: it does \fInot\fR include the |
| predefined macros, and it outputs \fIboth\fR the \fB#define\fR |
| directives and the result of preprocessing. Both kinds of output go to |
| the standard output file. |
| .IP "\fBN\fR" 4 |
| .IX Item "N" |
| Like \fBD\fR, but emit only the macro names, not their expansions. |
| .IP "\fBI\fR" 4 |
| .IX Item "I" |
| Output \fB#include\fR directives in addition to the result of |
| preprocessing. |
| .IP "\fBU\fR" 4 |
| .IX Item "U" |
| Like \fBD\fR except that only macros that are expanded, or whose |
| definedness is tested in preprocessor directives, are output; the |
| output is delayed until the use or test of the macro; and |
| \&\fB#undef\fR directives are also output for macros tested but |
| undefined at the time. |
| .RE |
| .RS 4 |
| .RE |
| .IP "\fB\-P\fR" 4 |
| .IX Item "-P" |
| Inhibit generation of linemarkers in the output from the preprocessor. |
| This might be useful when running the preprocessor on something that is |
| not C code, and will be sent to a program which might be confused by the |
| linemarkers. |
| .IP "\fB\-C\fR" 4 |
| .IX Item "-C" |
| Do not discard comments. All comments are passed through to the output |
| file, except for comments in processed directives, which are deleted |
| along with the directive. |
| .Sp |
| You should be prepared for side effects when using \fB\-C\fR; it |
| causes the preprocessor to treat comments as tokens in their own right. |
| For example, comments appearing at the start of what would be a |
| directive line have the effect of turning that line into an ordinary |
| source line, since the first token on the line is no longer a \fB#\fR. |
| .IP "\fB\-CC\fR" 4 |
| .IX Item "-CC" |
| Do not discard comments, including during macro expansion. This is |
| like \fB\-C\fR, except that comments contained within macros are |
| also passed through to the output file where the macro is expanded. |
| .Sp |
| In addition to the side-effects of the \fB\-C\fR option, the |
| \&\fB\-CC\fR option causes all \*(C+\-style comments inside a macro |
| to be converted to C\-style comments. This is to prevent later use |
| of that macro from inadvertently commenting out the remainder of |
| the source line. |
| .Sp |
| The \fB\-CC\fR option is generally used to support lint comments. |
| .IP "\fB\-traditional\-cpp\fR" 4 |
| .IX Item "-traditional-cpp" |
| Try to imitate the behavior of old-fashioned C preprocessors, as |
| opposed to \s-1ISO\s0 C preprocessors. |
| .IP "\fB\-trigraphs\fR" 4 |
| .IX Item "-trigraphs" |
| Process trigraph sequences. |
| .IP "\fB\-remap\fR" 4 |
| .IX Item "-remap" |
| Enable special code to work around file systems which only permit very |
| short file names, such as MS-DOS. |
| .IP "\fB\-\-help\fR" 4 |
| .IX Item "--help" |
| .PD 0 |
| .IP "\fB\-\-target\-help\fR" 4 |
| .IX Item "--target-help" |
| .PD |
| Print text describing all the command-line options instead of |
| preprocessing anything. |
| .IP "\fB\-v\fR" 4 |
| .IX Item "-v" |
| 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. |
| .IP "\fB\-H\fR" 4 |
| .IX Item "-H" |
| Print the name of each header file used, in addition to other normal |
| activities. Each name is indented to show how deep in the |
| \&\fB#include\fR stack it is. Precompiled header files are also |
| printed, even if they are found to be invalid; an invalid precompiled |
| header file is printed with \fB...x\fR and a valid one with \fB...!\fR . |
| .IP "\fB\-version\fR" 4 |
| .IX Item "-version" |
| .PD 0 |
| .IP "\fB\-\-version\fR" 4 |
| .IX Item "--version" |
| .PD |
| Print out \s-1GNU\s0 \s-1CPP\s0's version number. With one dash, proceed to |
| preprocess as normal. With two dashes, exit immediately. |
| .SH "ENVIRONMENT" |
| .IX Header "ENVIRONMENT" |
| This section describes the environment variables that affect how \s-1CPP\s0 |
| operates. You can use them to specify directories or prefixes to use |
| when searching for include files, or to control dependency output. |
| .PP |
| Note that you can also specify places to search using options such as |
| \&\fB\-I\fR, and control dependency output with options like |
| \&\fB\-M\fR. These take precedence over |
| environment variables, which in turn take precedence over the |
| configuration of \s-1GCC\s0. |
| .IP "\fB\s-1CPATH\s0\fR" 4 |
| .IX Item "CPATH" |
| .PD 0 |
| .IP "\fBC_INCLUDE_PATH\fR" 4 |
| .IX Item "C_INCLUDE_PATH" |
| .IP "\fB\s-1CPLUS_INCLUDE_PATH\s0\fR" 4 |
| .IX Item "CPLUS_INCLUDE_PATH" |
| .IP "\fB\s-1OBJC_INCLUDE_PATH\s0\fR" 4 |
| .IX Item "OBJC_INCLUDE_PATH" |
| .PD |
| Each variable's value is a list of directories separated by a special |
| character, much like \fB\s-1PATH\s0\fR, in which to look for header files. |
| The special character, \f(CW\*(C`PATH_SEPARATOR\*(C'\fR, is target-dependent and |
| determined at \s-1GCC\s0 build time. For Microsoft Windows-based targets it is a |
| semicolon, and for almost all other targets it is a colon. |
| .Sp |
| \&\fB\s-1CPATH\s0\fR specifies a list of directories to be searched as if |
| specified with \fB\-I\fR, but after any paths given with \fB\-I\fR |
| options on the command line. This environment variable is used |
| regardless of which language is being preprocessed. |
| .Sp |
| The remaining environment variables apply only when preprocessing the |
| particular language indicated. Each specifies a list of directories |
| to be searched as if specified with \fB\-isystem\fR, but after any |
| paths given with \fB\-isystem\fR options on the command line. |
| .Sp |
| In all these variables, an empty element instructs the compiler to |
| search its current working directory. Empty elements can appear at the |
| beginning or end of a path. For instance, if the value of |
| \&\fB\s-1CPATH\s0\fR is \f(CW\*(C`:/special/include\*(C'\fR, that has the same |
| effect as \fB\-I.\ \-I/special/include\fR. |
| .IP "\fB\s-1DEPENDENCIES_OUTPUT\s0\fR" 4 |
| .IX Item "DEPENDENCIES_OUTPUT" |
| If this variable is set, its value specifies how to output |
| dependencies for Make based on the non-system header files processed |
| by the compiler. System header files are ignored in the dependency |
| output. |
| .Sp |
| The value of \fB\s-1DEPENDENCIES_OUTPUT\s0\fR can be just a file name, in |
| which case the Make rules are written to that file, guessing the target |
| name from the source file name. Or the value can have the form |
| \&\fIfile\fR\fB \fR\fItarget\fR, in which case the rules are written to |
| file \fIfile\fR using \fItarget\fR as the target name. |
| .Sp |
| In other words, this environment variable is equivalent to combining |
| the options \fB\-MM\fR and \fB\-MF\fR, |
| with an optional \fB\-MT\fR switch too. |
| .IP "\fB\s-1SUNPRO_DEPENDENCIES\s0\fR" 4 |
| .IX Item "SUNPRO_DEPENDENCIES" |
| This variable is the same as \fB\s-1DEPENDENCIES_OUTPUT\s0\fR (see above), |
| except that system header files are not ignored, so it implies |
| \&\fB\-M\fR rather than \fB\-MM\fR. However, the dependence on the |
| main input file is omitted. |
| .SH "SEE ALSO" |
| .IX Header "SEE ALSO" |
| \&\fIgpl\fR\|(7), \fIgfdl\fR\|(7), \fIfsf\-funding\fR\|(7), |
| \&\fIgcc\fR\|(1), \fIas\fR\|(1), \fIld\fR\|(1), and the Info entries for \fIcpp\fR, \fIgcc\fR, and |
| \&\fIbinutils\fR. |
| .SH "COPYRIGHT" |
| .IX Header "COPYRIGHT" |
| Copyright (c) 1987\-2015 Free Software Foundation, Inc. |
| .PP |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the \s-1GNU\s0 Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation. A copy of |
| the license is included in the |
| man page \fIgfdl\fR\|(7). |
| This manual contains no Invariant Sections. The Front-Cover Texts are |
| (a) (see below), and the Back-Cover Texts are (b) (see below). |
| .PP |
| (a) The \s-1FSF\s0's Front-Cover Text is: |
| .PP |
| .Vb 1 |
| \& A GNU Manual |
| .Ve |
| .PP |
| (b) The \s-1FSF\s0's Back-Cover Text is: |
| .PP |
| .Vb 3 |
| \& You have freedom to copy and modify this GNU Manual, like GNU |
| \& software. Copies published by the Free Software Foundation raise |
| \& funds for GNU development. |
| .Ve |