компилятор C и C ++ проекта GNU (GNU project C and C++ compiler)
Параметры подробно (Options detail)
Controlling the Preprocessor
These options control the C preprocessor, which is run on each C
source file before actual compilation.
If you use the -E option, nothing is done except preprocessing.
Some of these options make sense only together with -E because
they cause the preprocessor output to be unsuitable for actual
compilation.
In addition to the options listed here, there are a number of
options to control search paths for include files documented in
Directory Options. Options to control preprocessor diagnostics
are listed in Warning Options.
-D name
Predefine name as a macro, with definition 1.
-D name=definition
The contents of definition are tokenized and processed as if
they appeared during translation phase three in a #define
directive. In particular, the definition is 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 should quote the option. With sh and
csh, -D'name(args...)=definition' works.
-D and -U options are processed in the order they are given
on the command line. All -imacros file and -include file
options are processed after all -D and -U options.
-U name
Cancel any previous definition of name, either built in or
provided with a -D option.
-include file
Process file as if "#include "file"" appeared as the first
line of the primary source file. However, the first
directory searched for file is the preprocessor's working
directory instead of 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 -include options are given, the files are
included in the order they appear on the command line.
-imacros file
Exactly like -include, except that any output produced by
scanning file 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 -imacros are processed before all
files specified by -include.
-undef
Do not predefine any system-specific or GCC-specific macros.
The standard predefined macros remain defined.
-pthread
Define additional macros required for using the POSIX threads
library. You should use this option consistently for both
compilation and linking. This option is supported on
GNU/Linux targets, most other Unix derivatives, and also on
x86 Cygwin and MinGW targets.
-M Instead of outputting the result of preprocessing, output a
rule suitable for make describing the dependencies of the
main source file. The preprocessor outputs one make rule
containing the object file name for that source file, a
colon, and the names of all the included files, including
those coming from -include or -imacros command-line options.
Unless specified explicitly (with -MT or -MQ), 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 \-newline.
The rule has no commands.
This option does not suppress the preprocessor's debug
output, such as -dM. To avoid mixing such debug output with
the dependency rules you should explicitly specify the
dependency output file with -MF, or use an environment
variable like DEPENDENCIES_OUTPUT. Debug output is still
sent to the regular output stream as normal.
Passing -M to the driver implies -E, and suppresses warnings
with an implicit -w.
-MM Like -M 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 #include directive does not in itself determine
whether that header appears in -MM dependency output.
-MF file
When used with -M or -MM, specifies a file to write the
dependencies to. If no -MF switch is given the preprocessor
sends the rules to the same place it would send preprocessed
output.
When used with the driver options -MD or -MMD, -MF overrides
the default dependency output file.
If file is -, then the dependencies are written to stdout.
-MG In conjunction with an option such as -M requesting
dependency generation, -MG 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.
-MG also suppresses preprocessed output, as a missing header
file renders this useless.
This feature is used in automatic updating of makefiles.
-MP 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 make gives
if you remove header files without updating the Makefile to
match.
This is typical output:
test.o: test.c test.h
test.h:
-MT target
Change the target of the rule emitted by dependency
generation. By default CPP takes the name of the main input
file, deletes any directory components and any file suffix
such as .c, and appends the platform's usual object suffix.
The result is the target.
An -MT option sets the target to be exactly the string you
specify. If you want multiple targets, you can specify them
as a single argument to -MT, or use multiple -MT options.
For example, -MT '$(objpfx)foo.o' might give
$(objpfx)foo.o: foo.c
-MQ target
Same as -MT, but it quotes any characters which are special
to Make. -MQ '$(objpfx)foo.o' gives
$$(objpfx)foo.o: foo.c
The default target is automatically quoted, as if it were
given with -MQ.
-MD -MD is equivalent to -M -MF file, except that -E is not
implied. The driver determines file based on whether an -o
option is given. If it is, the driver uses its argument but
with a suffix of .d, otherwise it takes the name of the input
file, removes any directory components and suffix, and
applies a .d suffix.
If -MD is used in conjunction with -E, any -o switch is
understood to specify the dependency output file, but if used
without -E, each -o is understood to specify a target object
file.
Since -E is not implied, -MD can be used to generate a
dependency output file as a side effect of the compilation
process.
-MMD
Like -MD except mention only user header files, not system
header files.
-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 -C to the compiler without problems. In
this mode the integrated preprocessor is little more than a
tokenizer for the front ends.
-fpreprocessed is implicit if the input file has one of the
extensions .i, .ii or .mi. These are the extensions that GCC
uses for preprocessed files created by -save-temps.
-fdirectives-only
When preprocessing, handle directives, but do not expand
macros.
The option's behavior depends on the -E and -fpreprocessed
options.
With -E, preprocessing is limited to the handling of
directives such as "#define", "#ifdef", and "#error". Other
preprocessor operations, such as macro expansion and trigraph
conversion are not performed. In addition, the -dD option is
implicitly enabled.
With -fpreprocessed, predefinition of command line and most
builtin macros is disabled. Macros such as "__LINE__", which
are contextually dependent, are handled normally. This
enables compilation of files previously preprocessed with "-E
-fdirectives-only".
With both -E and -fpreprocessed, the rules for -fpreprocessed
take precedence. This enables full preprocessing of files
previously preprocessed with "-E -fdirectives-only".
-fdollars-in-identifiers
Accept $ in identifiers.
-fextended-identifiers
Accept universal character names in identifiers. This option
is enabled by default for C99 (and later C standard versions)
and C++.
-fno-canonical-system-headers
When preprocessing, do not shorten system header paths with
canonicalization.
-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.
-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 level parameter can be
used to choose the level of precision of token location
tracking thus decreasing the memory consumption if necessary.
Value 0 of level de-activates this option. Value 1 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 2 tracks tokens locations completely.
This value is the most memory hungry. When this option is
given no argument, the default parameter value is 2.
Note that "-ftrack-macro-expansion=2" is activated by
default.
-fmacro-prefix-map=old=new
When preprocessing files residing in directory old, expand
the "__FILE__" and "__BASE_FILE__" macros as if the files
resided in directory new instead. This can be used to change
an absolute path to a relative path by using . for new which
can result in more reproducible builds that are location
independent. This option also affects "__builtin_FILE()"
during compilation. See also -ffile-prefix-map.
-fexec-charset=charset
Set the execution character set, used for string and
character constants. The default is UTF-8. charset can be
any encoding supported by the system's "iconv" library
routine.
-fwide-exec-charset=charset
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
-fexec-charset, charset 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".
-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 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. charset can be any
encoding supported by the system's "iconv" library routine.
-fpch-deps
When using precompiled headers, this flag causes the
dependency-output flags to also list the files from the
precompiled header's dependencies. If not specified, only
the precompiled header are listed and not the files that were
used to create it, because those files are not consulted when
a precompiled header is used.
-fpch-preprocess
This option allows use of a precompiled header together with
-E. It inserts a special "#pragma", "#pragma GCC
pch_preprocess "filename"" in the output to mark the place
where the precompiled header was found, and its filename.
When -fpreprocessed is in use, GCC recognizes this "#pragma"
and loads the PCH.
This option is off by default, because the resulting
preprocessed output is only really suitable as input to GCC.
It is switched on by -save-temps.
You should not write this "#pragma" in your own code, but it
is safe to edit the filename if the PCH file is available in
a different location. The filename may be absolute or it may
be relative to GCC's current directory.
-fworking-directory
Enable generation of linemarkers in the preprocessor output
that let the compiler know the current working directory at
the time of preprocessing. When this option is enabled, the
preprocessor emits, after the initial linemarker, a second
linemarker with the current working directory followed by two
slashes. GCC uses this directory, when it's present in the
preprocessed input, as the directory emitted as the current
working directory in some debugging information formats.
This option is implicitly enabled if debugging information is
enabled, but this can be inhibited with the negated form
-fno-working-directory. If the -P flag is present in the
command line, this option has no effect, since no "#line"
directives are emitted whatsoever.
-A predicate=answer
Make an assertion with the predicate predicate and answer
answer. This form is preferred to the older form -A
predicate(answer), which is still supported, because it does
not use shell special characters.
-A -predicate=answer
Cancel an assertion with the predicate predicate and answer
answer.
-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.
You should be prepared for side effects when using -C; 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 #.
-CC Do not discard comments, including during macro expansion.
This is like -C, 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 -C option, the -CC
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 -CC option is generally used to support lint comments.
-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.
-traditional
-traditional-cpp
Try to imitate the behavior of pre-standard C preprocessors,
as opposed to ISO C preprocessors. See the GNU CPP manual
for details.
Note that GCC does not otherwise attempt to emulate a pre-
standard C compiler, and these options are only supported
with the -E switch, or when invoking CPP explicitly.
-trigraphs
Support ISO C trigraphs. These are three-character
sequences, all starting with ??, that are defined by ISO C to
stand for single characters. For example, ??/ stands for \,
so '??/n' is a character constant for a newline.
The nine trigraphs and their replacements are
Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??-
Replacement: [ ] { } # \ ^ | ~
By default, GCC ignores trigraphs, but in standard-conforming
modes it converts them. See the -std and -ansi options.
-remap
Enable special code to work around file systems which only
permit very short file names, such as MS-DOS.
-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 #include 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 ...x and a valid one
with ...! .
-dletters
Says to make debugging dumps during compilation as specified
by letters. The flags documented here are those relevant to
the preprocessor. Other letters are interpreted by the
compiler proper, or reserved for future versions of GCC, and
so are silently ignored. If you specify letters whose
behavior conflicts, the result is undefined.
-dM Instead of the normal output, generate a list of #define
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 foo.h, the command
touch foo.h; cpp -dM foo.h
shows all the predefined macros.
If you use -dM without the -E option, -dM is interpreted
as a synonym for -fdump-rtl-mach.
-dD Like -dM except in two respects: it does not include the
predefined macros, and it outputs both the #define
directives and the result of preprocessing. Both kinds
of output go to the standard output file.
-dN Like -dD, but emit only the macro names, not their
expansions.
-dI Output #include directives in addition to the result of
preprocessing.
-dU Like -dD 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 #undef directives are also output for
macros tested but undefined at the time.
-fdebug-cpp
This option is only useful for debugging GCC. When used from
CPP or with -E, it dumps debugging information about location
maps. Every token in the output is preceded by the dump of
the map its location belongs to.
When used from GCC without -E, this option has no effect.
-Wp,option
You can use -Wp,option to bypass the compiler driver and pass
option directly through to the preprocessor. If option
contains commas, it is split into multiple options at the
commas. However, many options are modified, translated or
interpreted by the compiler driver before being passed to the
preprocessor, and -Wp forcibly bypasses this phase. The
preprocessor's direct interface is undocumented and subject
to change, so whenever possible you should avoid using -Wp
and let the driver handle the options instead.
-Xpreprocessor option
Pass option as an option to the preprocessor. You can use
this to supply system-specific preprocessor options that GCC
does not recognize.
If you want to pass an option that takes an argument, you
must use -Xpreprocessor twice, once for the option and once
for the argument.
-no-integrated-cpp
Perform preprocessing as a separate pass before compilation.
By default, GCC performs preprocessing as an integrated part
of input tokenization and parsing. If this option is
provided, the appropriate language front end (cc1, cc1plus,
or cc1obj for C, C++, and Objective-C, respectively) is
instead invoked twice, once for preprocessing only and once
for actual compilation of the preprocessed input. This
option may be useful in conjunction with the -B or -wrapper
options to specify an alternate preprocessor or perform
additional processing of the program source between normal
preprocessing and compilation.
Passing Options to the Assembler
You can pass options to the assembler.
-Wa,option
Pass option as an option to the assembler. If option
contains commas, it is split into multiple options at the
commas.
-Xassembler option
Pass option as an option to the assembler. You can use this
to supply system-specific assembler options that GCC does not
recognize.
If you want to pass an option that takes an argument, you
must use -Xassembler twice, once for the option and once for
the argument.
