CPP 1 2006-05-06 gcc-4.1.1 GNU
NAME
cpp - The C Preprocessor
SYNOPSIS
cpp [--DD_m_a_c_r_o[=_d_e_f_n]...] [--UU_m_a_c_r_o]
[--II_d_i_r...] [--iiqquuoottee_d_i_r...]
[--WW_w_a_r_n...]
[--MM|--MMMM] [--MMGG] [--MMFF _f_i_l_e_n_a_m_e]
[--MMPP] [--MMQQ _t_a_r_g_e_t...]
[--MMTT _t_a_r_g_e_t...]
[--PP] [--ffnnoo--wwoorrkkiinngg--ddiirreeccttoorryy]
[--xx _l_a_n_g_u_a_g_e] [--ssttdd==_s_t_a_n_d_a_r_d]
_i_n_f_i_l_e _o_u_t_f_i_l_e
Only the most useful options are listed here; see below for the remainder.
DESCRIPTION
The C preprocessor, often known as _c_p_p, is a _m_a_c_r_o _p_r_o_c_e_s_s_o_r
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 _m_a_c_r_o_s, which are brief abbreviations for longer
constructs.
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.
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. --ttrraaddiittiioonnaall--ccpppp
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.
Wherever possible, you should use a preprocessor geared to the language
you are writing in. Modern versions of the GNU 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 GNU M4.
C preprocessors vary in some details. This manual discusses the GNU C
preprocessor, which provides a small superset of the features of ISO
Standard C. In its default mode, the GNU 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 ISO Standard C,
you should use the --ssttdd==cc8899 or --ssttdd==cc9999 options, depending
on which version of the standard you want. To get all the mandatory
diagnostics, you must also use --ppeeddaannttiicc.
This manual describes the behavior of the ISO preprocessor. To
minimize gratuitous differences, where the ISO 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 TTrraaddiittiioonnaall
MMooddee.
For clarity, unless noted otherwise, references to CCPPPP in this
manual refer to GNU CPP.
OPTIONS
The C preprocessor expects two file names as arguments, _i_n_f_i_l_e and
_o_u_t_f_i_l_e. The preprocessor reads _i_n_f_i_l_e together with any
other files it specifies with ##iinncclluuddee. All the output generated
by the combined input files is written in _o_u_t_f_i_l_e.
Either _i_n_f_i_l_e or _o_u_t_f_i_l_e may be --, which as
_i_n_f_i_l_e means to read from standard input and as _o_u_t_f_i_l_e
means to write to standard output. Also, if either file is omitted, it
means the same as if -- had been specified for that file.
Unless otherwise noted, or the option ends in ==, all options
which take an argument may have that argument appear either immediately
after the option, or with a space between option and argument:
--IIffoooo and --II ffoooo have the same effect.
Many options have multi-letter names; therefore multiple single-letter
options may _n_o_t be grouped: --ddMM is very different from
--dd --MM.
-
--DD _n_a_m_e
Predefine _n_a_m_e as a macro, with definition 1.
-
-
--DD _n_a_m_e==_d_e_f_i_n_i_t_i_o_n
The contents of _d_e_f_i_n_i_t_i_o_n are tokenized and processed as if
-
they appeared during translation phase three in a ##ddeeffiinnee
directive. In particular, the definition will be truncated by
embedded newline characters.
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.
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 sshh and ccsshh,
--DD''_n_a_m_e((_a_r_g_s_._._.))==_d_e_f_i_n_i_t_i_o_n'' works.
--DD and --UU options are processed in the order they
are given on the command line. All --iimmaaccrrooss _f_i_l_e and
--iinncclluuddee _f_i_l_e options are processed after all
--DD and --UU options.
-
--UU _n_a_m_e
Cancel any previous definition of _n_a_m_e, either built in or
-
provided with a --DD option.
-
--uunnddeeff
Do not predefine any system-specific or GCC-specific macros. The
-
standard predefined macros remain defined.
-
--II _d_i_r
Add the directory _d_i_r to the list of directories to be searched
-
for header files.
Directories named by --II are searched before the standard
system include directories. If the directory _d_i_r 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
.
-
--oo _f_i_l_e
Write output to _f_i_l_e. This is the same as specifying _f_i_l_e
-
as the second non-option argument to ccpppp. ggcccc has a
different interpretation of a second non-option argument, so you must
use --oo to specify the output file.
-
--WWaallll
Turns on all optional warnings which are desirable for normal code.
-
At present this is --WWccoommmmeenntt, --WWttrriiggrraapphhss,
--WWmmuullttiicchhaarr and a warning about integer promotion causing a
change of sign in "#if" expressions. Note that many of the
preprocessor's warnings are on by default and have no options to
control them.
-
--WWccoommmmeenntt
-
-
--WWccoommmmeennttss
Warn whenever a comment-start sequence //** appears in a //**
-
comment, or whenever a backslash-newline appears in a //// comment.
(Both forms have the same effect.)
-
--WWttrriiggrraapphhss
@anchor{Wtrigraphs}
-
Most trigraphs in comments cannot affect the meaning of the program.
However, a trigraph that would form an escaped newline (????// 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.
This option is implied by --WWaallll. If --WWaallll is not
given, this option is still enabled unless trigraphs are enabled. To
get trigraph conversion without warnings, but get the other
--WWaallll warnings, use --ttrriiggrraapphhss --WWaallll --WWnnoo--ttrriiggrraapphhss.
-
--WWttrraaddiittiioonnaall
Warn about certain constructs that behave differently in traditional and
-
ISO C. Also warn about ISO C constructs that have no traditional C
equivalent, and problematic constructs which should be avoided.
-
--WWiimmppoorrtt
Warn the first time ##iimmppoorrtt is used.
-
-
--WWuunnddeeff
Warn whenever an identifier which is not a macro is encountered in an
-
##iiff directive, outside of ddeeffiinneedd. Such identifiers are
replaced with zero.
-
--WWuunnuusseedd--mmaaccrrooss
Warn about macros defined in the main file that are unused. A macro
-
is _u_s_e_d 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.
Built-in macros, macros defined on the command line, and macros
defined in include files are not warned about.
_N_o_t_e_: If a macro is actually used, but only used in skipped
conditional blocks, then CPP 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:
#if defined the_macro_causing_the_warning
#endif
-
--WWeennddiiff--llaabbeellss
Warn whenever an ##eellssee or an ##eennddiiff are followed by text.
-
This usually happens in code of the form
#if FOO
...
#else FOO
...
#endif FOO
The second and third "FOO" should be in comments, but often are not
in older programs. This warning is on by default.
-
--WWeerrrroorr
Make all warnings into hard errors. Source code which triggers warnings
-
will be rejected.
-
--WWssyysstteemm--hheeaaddeerrss
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.
-
--ww
Suppress all warnings, including those which GNU CPP issues by default.
-
-
--ppeeddaannttiicc
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.
-
--ppeeddaannttiicc--eerrrroorrss
Issue all the mandatory diagnostics, and make all mandatory diagnostics
-
into errors. This includes mandatory diagnostics that GCC issues
without --ppeeddaannttiicc but treats as warnings.
-
--MM
Instead of outputting the result of preprocessing, output a rule
-
suitable for mmaakkee describing the dependencies of the main
source file. The preprocessor outputs one mmaakkee rule containing
the object file name for that source file, a colon, and the names of all
the included files, including those coming from --iinncclluuddee or
--iimmaaccrrooss command line options.
Unless specified explicitly (with --MMTT or --MMQQ), the
object file name consists of the basename of the source file with any
suffix replaced with object file suffix. If there are many included
files then the rule is split into several lines using \\-newline.
The rule has no commands.
This option does not suppress the preprocessor's debug output, such as
--ddMM. To avoid mixing such debug output with the dependency
rules you should explicitly specify the dependency output file with
--MMFF, or use an environment variable like
DDEEPPEENNDDEENNCCIIEESS__OOUUTTPPUUTT. Debug output
will still be sent to the regular output stream as normal.
Passing --MM to the driver implies --EE, and suppresses
warnings with an implicit --ww.
-
--MMMM
Like --MM 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.
This implies that the choice of angle brackets or double quotes in an
##iinncclluuddee directive does not in itself determine whether that
header will appear in --MMMM dependency output. This is a
slight change in semantics from GCC versions 3.0 and earlier.
@anchor{dashMF}
-
--MMFF _f_i_l_e
When used with --MM or --MMMM, specifies a
-
file to write the dependencies to. If no --MMFF switch is given
the preprocessor sends the rules to the same place it would have sent
preprocessed output.
When used with the driver options --MMDD or --MMMMDD,
--MMFF overrides the default dependency output file.
-
--MMGG
In conjunction with an option such as --MM requesting
-
dependency generation, --MMGG 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
"#include" directive without prepending any path. --MMGG
also suppresses preprocessed output, as a missing header file renders
this useless.
This feature is used in automatic updating of makefiles.
-
--MMPP
This option instructs CPP to add a phony target for each dependency
-
other than the main file, causing each to depend on nothing. These
dummy rules work around errors mmaakkee gives if you remove header
files without updating the _M_a_k_e_f_i_l_e to match.
This is typical output:
test.o: test.c test.h
test.h:
-
--MMTT _t_a_r_g_e_t
Change the target of the rule emitted by dependency generation. By
-
default CPP takes the name of the main input file, including any path,
deletes any file suffix such as ..cc, and appends the platform's
usual object suffix. The result is the target.
An --MMTT 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 --MMTT, or use multiple --MMTT options.
For example, --MMTT ''$$((oobbjjppffxx))ffoooo..oo'' might give
$(objpfx)foo.o: foo.c
-
--MMQQ _t_a_r_g_e_t
Same as --MMTT, but it quotes any characters which are special to
-
Make. --MMQQ ''$$((oobbjjppffxx))ffoooo..oo'' gives
$$(objpfx)foo.o: foo.c
The default target is automatically quoted, as if it were given with
--MMQQ.
-
--MMDD
--MMDD is equivalent to --MM --MMFF _f_i_l_e, except that
-
--EE is not implied. The driver determines _f_i_l_e based on
whether an --oo option is given. If it is, the driver uses its
argument but with a suffix of _._d, otherwise it take the
basename of the input file and applies a _._d suffix.
If --MMDD is used in conjunction with --EE, any
--oo switch is understood to specify the dependency output file
(but @pxref{dashMF,,-MF}), but if used without --EE, each --oo
is understood to specify a target object file.
Since --EE is not implied, --MMDD can be used to generate
a dependency output file as a side-effect of the compilation process.
-
--MMMMDD
Like --MMDD except mention only user header files, not system
-
header files.
-
--xx cc
-
-
--xx cc++++
-
-
--xx oobbjjeeccttiivvee--cc
-
-
--xx aasssseemmbblleerr--wwiitthh--ccpppp
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:
..cc, ..cccc, ..mm, or ..SS. 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.
_N_o_t_e_: Previous versions of cpp accepted a --llaanngg option
which selected both the language and the standards conformance level.
This option has been removed, because it conflicts with the --ll
option.
-
--ssttdd==_s_t_a_n_d_a_r_d
-
-
--aannssii
Specify the standard to which the code should conform. Currently CPP
-
knows about C and C++ standards; others may be added in the future.
_s_t_a_n_d_a_r_d
may be one of:
-
"iso9899:1990"
-
-
"c89"
The ISO C standard from 1990. cc8899 is the customary shorthand for
-
this version of the standard.
The --aannssii option is equivalent to --ssttdd==cc8899.
-
"iso9899:199409"
The 1990 C standard, as amended in 1994.
-
-
"iso9899:1999"
-
-
"c99"
-
-
"iso9899:199x"
-
-
"c9x"
The revised ISO C standard, published in December 1999. Before
-
publication, this was known as C9X.
-
"gnu89"
The 1990 C standard plus GNU extensions. This is the default.
-
-
"gnu99"
-
-
"gnu9x"
The 1999 C standard plus GNU extensions.
-
-
"c++98"
The 1998 ISO C++ standard plus amendments.
-
-
"gnu++98"
The same as --ssttdd==cc++++9988 plus GNU extensions. This is the
-
default for C++ code.
-
--II--
Split the include path. Any directories specified with --II
-
options before --II-- are searched only for headers requested with
"#include "file""; they are not searched for
"#include ". If additional directories are
specified with --II options after the --II--, those
directories are searched for all ##iinncclluuddee directives.
In addition, --II-- inhibits the use of the directory of the current
file directory as the first search directory for "#include "file"".
This option has been deprecated.
-
--nnoossttddiinncc
Do not search the standard system directories for header files.
-
Only the directories you have specified with --II options
(and the directory of the current file, if appropriate) are searched.
-
--nnoossttddiinncc++++
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.)
-
--iinncclluuddee _f_i_l_e
Process _f_i_l_e as if "#include "file"" appeared as the first
-
line of the primary source file. However, the first directory searched
for _f_i_l_e is the preprocessor's working directory _i_n_s_t_e_a_d _o_f
the directory containing the main source file. If not found there, it
is searched for in the remainder of the "#include "..."" search
chain as normal.
If multiple --iinncclluuddee options are given, the files are included
in the order they appear on the command line.
-
--iimmaaccrrooss _f_i_l_e
Exactly like --iinncclluuddee, except that any output produced by
-
scanning _f_i_l_e is thrown away. Macros it defines remain defined.
This allows you to acquire all the macros from a header without also
processing its declarations.
All files specified by --iimmaaccrrooss are processed before all files
specified by --iinncclluuddee.
-
--iiddiirraafftteerr _d_i_r
Search _d_i_r for header files, but do it _a_f_t_e_r all
-
directories specified with --II and the standard system directories
have been exhausted. _d_i_r is treated as a system include directory.
-
--iipprreeffiixx _p_r_e_f_i_x
Specify _p_r_e_f_i_x as the prefix for subsequent --iiwwiitthhpprreeffiixx
-
options. If the prefix represents a directory, you should include the
final //.
-
--iiwwiitthhpprreeffiixx _d_i_r
-
-
--iiwwiitthhpprreeffiixxbbeeffoorree _d_i_r
Append _d_i_r to the prefix specified previously with
-
--iipprreeffiixx, and add the resulting directory to the include search
path. --iiwwiitthhpprreeffiixxbbeeffoorree puts it in the same place --II
would; --iiwwiitthhpprreeffiixx puts it where --iiddiirraafftteerr would.
-
--iissyyssrroooott _d_i_r
This option is like the ----ssyyssrroooott option, but applies only to
-
header files. See the ----ssyyssrroooott option for more information.
-
--iissyysstteemm _d_i_r
Search _d_i_r for header files, after all directories specified by
-
--II 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.
-
--iiqquuoottee _d_i_r
Search _d_i_r only for header files requested with
-
"#include "file""; they are not searched for
"#include ", before all directories specified by
--II and before the standard system directories.
-
--ffddoollllaarrss--iinn--iiddeennttiiffiieerrss
@anchor{fdollars-in-identifiers}
-
Accept $$ in identifiers.
-
--ffeexxtteennddeedd--iiddeennttiiffiieerrss
Accept universal character names in identifiers. This option is
-
experimental; in a future version of GCC, it will be enabled by
default for C99 and C++.
-
--ffpprreepprroocceesssseedd
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 --CC to the compiler without
problems. In this mode the integrated preprocessor is little more than
a tokenizer for the front ends.
--ffpprreepprroocceesssseedd is implicit if the input file has one of the
extensions ..ii, ..iiii or ..mmii. These are the
extensions that GCC uses for preprocessed files created by
--ssaavvee--tteemmppss.
-
--ffttaabbssttoopp==_w_i_d_t_h
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.
-
--ffeexxeecc--cchhaarrsseett==_c_h_a_r_s_e_t
Set the execution character set, used for string and character
-
constants. The default is UTF-8. _c_h_a_r_s_e_t can be any encoding
supported by the system's "iconv" library routine.
-
--ffwwiiddee--eexxeecc--cchhaarrsseett==_c_h_a_r_s_e_t
Set the wide execution character set, used for wide string and
-
character constants. The default is UTF-32 or UTF-16, whichever
corresponds to the width of "wchar_t". As with
--ffeexxeecc--cchhaarrsseett, _c_h_a_r_s_e_t can be any encoding supported
by the system's "iconv" library routine; however, you will have
problems with encodings that do not fit exactly in "wchar_t".
-
--ffiinnppuutt--cchhaarrsseett==_c_h_a_r_s_e_t
Set the input character set, used for translation from the character
-
set of the input file to the source character set used by GCC. If the
locale does not specify, or GCC cannot get this information from the
locale, the default is UTF-8. This can be overridden by either the locale
or this command line option. Currently the command line option takes
precedence if there's a conflict. _c_h_a_r_s_e_t can be any encoding
supported by the system's "iconv" library routine.
-
--ffwwoorrkkiinngg--ddiirreeccttoorryy
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. GCC 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 --ffnnoo--wwoorrkkiinngg--ddiirreeccttoorryy. If the --PP flag is
present in the command line, this option has no effect, since no
"#line" directives are emitted whatsoever.
-
--ffnnoo--sshhooww--ccoolluummnn
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 ddeejjaaggnnuu.
-
--AA _p_r_e_d_i_c_a_t_e==_a_n_s_w_e_r
Make an assertion with the predicate _p_r_e_d_i_c_a_t_e and answer
-
_a_n_s_w_e_r. This form is preferred to the older form --AA
_p_r_e_d_i_c_a_t_e((_a_n_s_w_e_r)), which is still supported, because
it does not use shell special characters.
-
--AA --_p_r_e_d_i_c_a_t_e==_a_n_s_w_e_r
Cancel an assertion with the predicate _p_r_e_d_i_c_a_t_e and answer
-
_a_n_s_w_e_r.
-
--ddCCHHAARRSS
_C_H_A_R_S 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 GCC, and so
are silently ignored. If you specify characters whose behavior
conflicts, the result is undefined.
-
MM
Instead of the normal output, generate a list of ##ddeeffiinnee
-
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 _f_o_o_._h, the command
touch foo.h; cpp -dM foo.h
will show all the predefined macros.
-
DD
Like MM except in two respects: it does _n_o_t include the
-
predefined macros, and it outputs _b_o_t_h the ##ddeeffiinnee
directives and the result of preprocessing. Both kinds of output go to
the standard output file.
-
NN
Like DD, but emit only the macro names, not their expansions.
-
-
II
Output ##iinncclluuddee directives in addition to the result of
-
preprocessing.
-
--PP
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.
-
--CC
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.
You should be prepared for side effects when using --CC; 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 ##.
-
--CCCC
Do not discard comments, including during macro expansion. This is
-
like --CC, except that comments contained within macros are
also passed through to the output file where the macro is expanded.
In addition to the side-effects of the --CC option, the
--CCCC 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.
The --CCCC option is generally used to support lint comments.
-
--ttrraaddiittiioonnaall--ccpppp
Try to imitate the behavior of old-fashioned C preprocessors, as
-
opposed to ISO C preprocessors.
-
--ttrriiggrraapphhss
Process trigraph sequences.
-
-
--rreemmaapp
Enable special code to work around file systems which only permit very
-
short file names, such as MS-DOS.
-
----hheellpp
-
-
----ttaarrggeett--hheellpp
Print text describing all the command line options instead of
-
preprocessing anything.
-
--vv
Verbose mode. Print out GNU CPP's version number at the beginning of
-
execution, and report the final form of the include path.
-
--HH
Print the name of each header file used, in addition to other normal
-
activities. Each name is indented to show how deep in the
##iinncclluuddee 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 ......xx and a valid one with ......!! .
-
--vveerrssiioonn
-
-
----vveerrssiioonn
Print out GNU CPP's version number. With one dash, proceed to
-
preprocess as normal. With two dashes, exit immediately.
ENVIRONMENT
This section describes the environment variables that affect how CPP
operates. You can use them to specify directories or prefixes to use
when searching for include files, or to control dependency output.
Note that you can also specify places to search using options such as
--II, and control dependency output with options like
--MM. These take precedence over
environment variables, which in turn take precedence over the
configuration of GCC.
-
CCPPAATTHH
-
-
CC__IINNCCLLUUDDEE__PPAATTHH
-
-
CCPPLLUUSS__IINNCCLLUUDDEE__PPAATTHH
-
-
OOBBJJCC__IINNCCLLUUDDEE__PPAATTHH
Each variable's value is a list of directories separated by a special
-
character, much like PPAATTHH, in which to look for header files.
The special character, "PATH_SEPARATOR", is target-dependent and
determined at GCC build time. For Microsoft Windows-based targets it is a
semicolon, and for almost all other targets it is a colon.
CCPPAATTHH specifies a list of directories to be searched as if
specified with --II, but after any paths given with --II
options on the command line. This environment variable is used
regardless of which language is being preprocessed.
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 --iissyysstteemm, but after any
paths given with --iissyysstteemm options on the command line.
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
CCPPAATTHH is ":/special/include", that has the same
effect as --II.. --II//ssppeecciiaall//iinncclluuddee.
-
DDEEPPEENNDDEENNCCIIEESS__OOUUTTPPUUTT
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.
The value of DDEEPPEENNDDEENNCCIIEESS__OOUUTTPPUUTT 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
_f_i_l_e _t_a_r_g_e_t, in which case the rules are written to
file _f_i_l_e using _t_a_r_g_e_t as the target name.
In other words, this environment variable is equivalent to combining
the options --MMMM and --MMFF,
with an optional --MMTT switch too.
-
SSUUNNPPRROO__DDEEPPEENNDDEENNCCIIEESS
This variable is the same as DDEEPPEENNDDEENNCCIIEESS__OOUUTTPPUUTT (see above),
-
except that system header files are not ignored, so it implies
--MM rather than --MMMM. However, the dependence on the
main input file is omitted.
SEE ALSO
_g_p_l(7), _g_f_d_l(7), _f_s_f_-_f_u_n_d_i_n_g(7),
_g_c_c(1), _a_s(1), _l_d(1), and the Info entries for _c_p_p, _g_c_c, and
_b_i_n_u_t_i_l_s.
COPYRIGHT
Copyright (c) 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996,
1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation. A copy of
the license is included in the
man page _g_f_d_l(7).
This manual contains no Invariant Sections. The Front-Cover Texts are
(a) (see below), and the Back-Cover Texts are (b) (see below).
(a) The FSF's Front-Cover Text is:
A GNU Manual
(b) The FSF's Back-Cover Text is:
You have freedom to copy and modify this GNU Manual, like GNU
software. Copies published by the Free Software Foundation raise
funds for GNU development.