+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 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; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Preprocessor Options, Next: Assembler Options, Prev: Optimize Options, Up: Invoking GCC
-
-Options 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.
-
- 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.
-
-`-D NAME'
- Predefine NAME as a macro, with definition `1'.
-
-`-D NAME=DEFINITION'
- Predefine NAME as a macro, with definition DEFINITION. There are
- no restrictions on the contents of DEFINITION, but 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 `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.
-
-`-undef'
- Do not predefine any system-specific macros. The common predefined
- macros remain defined.
-
-`-I DIR'
- Add the directory DIR to the list of directories to be searched
- for header files. Directories named by `-I' are searched before
- the standard system include directories.
-
- It is dangerous to specify a standard system include directory in
- an `-I' option. This defeats the special treatment of system
- headers . It can also defeat the repairs to buggy system headers
- which GCC makes when it is installed.
-
-`-o FILE'
- Write output to FILE. This is the same as specifying FILE as the
- second non-option argument to `cpp'. `gcc' has a different
- interpretation of a second non-option argument, so you must use
- `-o' to specify the output file.
-
-`-Wall'
- Turns on all optional warnings which are desirable for normal
- code. At present this is `-Wcomment' and `-Wtrigraphs'. Note that
- many of the preprocessor's warnings are on by default and have no
- options to control them.
-
-`-Wcomment'
-`-Wcomments'
- 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.)
-
-`-Wtrigraphs'
- Warn if any trigraphs are encountered. This option used to take
- effect only if `-trigraphs' was also specified, but now works
- independently. Warnings are not given for trigraphs within
- comments, as they do not affect the meaning of the program.
-
-`-Wtraditional'
- 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.
-
-`-Wimport'
- Warn the first time `#import' is used.
-
-`-Wundef'
- Warn whenever an identifier which is not a macro is encountered in
- an `#if' directive, outside of `defined'. Such identifiers are
- replaced with zero.
-
-`-Werror'
- Make all warnings into hard errors. Source code which triggers
- warnings will be rejected.
-
-`-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.
-
-`-w'
- Suppress all warnings, including those which GNU CPP issues by
- default.
-
-`-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.
-
-`-pedantic-errors'
- Issue all the mandatory diagnostics, and make all mandatory
- diagnostics into errors. This includes mandatory diagnostics that
- GCC issues without `-pedantic' but treats as warnings.
-
-`-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 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 `-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' (*note DEPENDENCIES_OUTPUT::). Debug output
- will still be sent to the regular output stream as normal.
-
- Passing `-M' to the driver implies `-E'.
-
-`-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 will appear in `-MM' dependency output. This is a slight
- change in semantics from GCC versions 3.0 and earlier.
-
-`-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 have sent preprocessed
- output.
-
- When used with the driver options `-MD' or `-MMD', `-MF' overrides
- the default dependency output file.
-
-`-MG'
- When used with `-M' or `-MM', `-MG' says to treat missing header
- files as generated files and assume they live in the same
- directory as the source file. It suppresses preprocessed output,
- as a missing header file is ordinarily an error.
-
- 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, including any
- path, deletes any file suffix such as `.c', and appends the
- platform's usual object suffix. The result is the target.
-
- An `-MT' option will set the target to be exactly the string you
- specify. If you want multiple targets, you can specify them as a
- single 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 take the basename of the input file
- 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 *note
- -MF::), 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.
-
-`-x c'
-`-x c++'
-`-x objective-c'
-`-x assembler-with-cpp'
- 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: `.c', `.cc', `.m', or `.S'. 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.
-
- *Note:* Previous versions of cpp accepted a `-lang' option which
- selected both the language and the standards conformance level.
- This option has been removed, because it conflicts with the `-l'
- option.
-
-`-std=STANDARD'
-`-ansi'
- Specify the standard to which the code should conform. Currently
- cpp only knows about the standards for C; other language standards
- will be added in the future.
-
- STANDARD may be one of:
- `iso9899:1990'
- `c89'
- The ISO C standard from 1990. `c89' is the customary
- shorthand for this version of the standard.
-
- The `-ansi' option is equivalent to `-std=c89'.
-
- `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.
-
-`-I-'
- Split the include path. Any directories specified with `-I'
- options before `-I-' are searched only for headers requested with
- `#include "FILE"'; they are not searched for `#include <FILE>'.
- If additional directories are specified with `-I' options after
- the `-I-', those directories are searched for all `#include'
- directives.
-
- In addition, `-I-' inhibits the use of the directory of the current
- file directory as the first search directory for `#include "FILE"'.
-
-`-nostdinc'
- Do not search the standard system directories for header files.
- Only the directories you have specified with `-I' options (and the
- directory of the current file, if appropriate) are searched.
-
-`-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.)
-
-`-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'.
-
-`-idirafter DIR'
- Search DIR for header files, but do it _after_ all directories
- specified with `-I' and the standard system directories have been
- exhausted. DIR is treated as a system include directory.
-
-`-iprefix PREFIX'
- Specify PREFIX as the prefix for subsequent `-iwithprefix'
- options. If the prefix represents a directory, you should include
- the final `/'.
-
-`-iwithprefix DIR'
-`-iwithprefixbefore DIR'
- Append DIR to the prefix specified previously with `-iprefix', and
- add the resulting directory to the include search path.
- `-iwithprefixbefore' puts it in the same place `-I' would;
- `-iwithprefix' puts it where `-idirafter' would.
-
- Use of these options is discouraged.
-
-`-isystem DIR'
- Search DIR for header files, after all directories specified by
- `-I' 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.
-
-`-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'.
-
-`-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.
-
-`-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 `dejagnu'.
-
-`-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.
-
-`-A-'
- Cancel all predefined assertions and all assertions preceding it on
- the command line. Also, undefine all predefined macros and all
- macros preceding it on the command line. (This is a historical
- wart and may change in the future.)
-
-`-dCHARS'
- CHARS 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.
-
- `M'
- 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
-
- will show all the predefined macros.
-
- `D'
- Like `M' 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.
-
- `N'
- Like `D', but emit only the macro names, not their expansions.
-
- `I'
- Output `#include' directives in addition to the result of
- preprocessing.
-
-`-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.
-
-`-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 `#'.
-
-`-gcc'
- Define the macros __GNUC__, __GNUC_MINOR__ and
- __GNUC_PATCHLEVEL__. These are defined automatically when you use
- `gcc -E'; you can turn them off in that case with `-no-gcc'.
-
-`-traditional'
- Try to imitate the behavior of old-fashioned C, as opposed to ISO
- C.
-
-`-trigraphs'
- Process trigraph sequences. 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. By default, GCC ignores
- trigraphs, but in standard-conforming modes it converts them. See
- the `-std' and `-ansi' options.
-
- The nine trigraphs and their replacements are
-
- Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??-
- Replacement: [ ] { } # \ ^ | ~
-
-`-remap'
- Enable special code to work around file systems which only permit
- very short file names, such as MS-DOS.
-
-`-$'
- Forbid the use of `$' in identifiers. The C standard allows
- implementations to define extra characters that can appear in
- identifiers. By default GNU CPP permits `$', a common extension.
-
-`-h'
-`--help'
-`--target-help'
- Print text describing all the command line options instead of
- preprocessing anything.
-
-`-v'
- Verbose mode. Print out GNU CPP's version number at the beginning
- of execution, and report the final form of the include path.
-
-`-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.
-
-`-version'
-`--version'
- Print out GNU CPP's version number. With one dash, proceed to
- preprocess as normal. With two dashes, exit immediately.
-
-\1f
-File: gcc.info, Node: Assembler Options, Next: Link Options, Prev: Preprocessor Options, Up: Invoking GCC
-
-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.
-
-\1f
-File: gcc.info, Node: Link Options, Next: Directory Options, Prev: Assembler Options, Up: Invoking GCC
-
-Options for Linking
-===================
-
- These options come into play when the compiler links object files
-into an executable output file. They are meaningless if the compiler is
-not doing a link step.
-
-`OBJECT-FILE-NAME'
- A file name that does not end in a special recognized suffix is
- considered to name an object file or library. (Object files are
- distinguished from libraries by the linker according to the file
- contents.) If linking is done, these object files are used as
- input to the linker.
-
-`-c'
-`-S'
-`-E'
- If any of these options is used, then the linker is not run, and
- object file names should not be used as arguments. *Note Overall
- Options::.
-
-`-lLIBRARY'
-`-l LIBRARY'
- Search the library named LIBRARY when linking. (The second
- alternative with the library as a separate argument is only for
- POSIX compliance and is not recommended.)
-
- It makes a difference where in the command you write this option;
- the linker searches and processes libraries and object files in
- the order they are specified. Thus, `foo.o -lz bar.o' searches
- library `z' after file `foo.o' but before `bar.o'. If `bar.o'
- refers to functions in `z', those functions may not be loaded.
-
- The linker searches a standard list of directories for the library,
- which is actually a file named `libLIBRARY.a'. The linker then
- uses this file as if it had been specified precisely by name.
-
- The directories searched include several standard system
- directories plus any that you specify with `-L'.
-
- Normally the files found this way are library files--archive files
- whose members are object files. The linker handles an archive
- file by scanning through it for members which define symbols that
- have so far been referenced but not defined. But if the file that
- is found is an ordinary object file, it is linked in the usual
- fashion. The only difference between using an `-l' option and
- specifying a file name is that `-l' surrounds LIBRARY with `lib'
- and `.a' and searches several directories.
-
-`-lobjc'
- You need this special case of the `-l' option in order to link an
- Objective-C program.
-
-`-nostartfiles'
- Do not use the standard system startup files when linking. The
- standard system libraries are used normally, unless `-nostdlib' or
- `-nodefaultlibs' is used.
-
-`-nodefaultlibs'
- Do not use the standard system libraries when linking. Only the
- libraries you specify will be passed to the linker. The standard
- startup files are used normally, unless `-nostartfiles' is used.
- The compiler may generate calls to memcmp, memset, and memcpy for
- System V (and ISO C) environments or to bcopy and bzero for BSD
- environments. These entries are usually resolved by entries in
- libc. These entry points should be supplied through some other
- mechanism when this option is specified.
-
-`-nostdlib'
- Do not use the standard system startup files or libraries when
- linking. No startup files and only the libraries you specify will
- be passed to the linker. The compiler may generate calls to
- memcmp, memset, and memcpy for System V (and ISO C) environments
- or to bcopy and bzero for BSD environments. These entries are
- usually resolved by entries in libc. These entry points should be
- supplied through some other mechanism when this option is
- specified.
-
- One of the standard libraries bypassed by `-nostdlib' and
- `-nodefaultlibs' is `libgcc.a', a library of internal subroutines
- that GCC uses to overcome shortcomings of particular machines, or
- special needs for some languages. (*Note Interfacing to GCC
- Output: (gccint)Interface, for more discussion of `libgcc.a'.) In
- most cases, you need `libgcc.a' even when you want to avoid other
- standard libraries. In other words, when you specify `-nostdlib'
- or `-nodefaultlibs' you should usually specify `-lgcc' as well.
- This ensures that you have no unresolved references to internal GCC
- library subroutines. (For example, `__main', used to ensure C++
- constructors will be called; *note `collect2': (gccint)Collect2..)
-
-`-s'
- Remove all symbol table and relocation information from the
- executable.
-
-`-static'
- On systems that support dynamic linking, this prevents linking
- with the shared libraries. On other systems, this option has no
- effect.
-
-`-shared'
- Produce a shared object which can then be linked with other
- objects to form an executable. Not all systems support this
- option. For predictable results, you must also specify the same
- set of options that were used to generate code (`-fpic', `-fPIC',
- or model suboptions) when you specify this option.(1)
-
-`-shared-libgcc'
-`-static-libgcc'
- On systems that provide `libgcc' as a shared library, these options
- force the use of either the shared or static version respectively.
- If no shared version of `libgcc' was built when the compiler was
- configured, these options have no effect.
-
- There are several situations in which an application should use the
- shared `libgcc' instead of the static version. The most common of
- these is when the application wishes to throw and catch exceptions
- across different shared libraries. In that case, each of the
- libraries as well as the application itself should use the shared
- `libgcc'.
-
- Therefore, the G++ and GCJ drivers automatically add
- `-shared-libgcc' whenever you build a shared library or a main
- executable, because C++ and Java programs typically use
- exceptions, so this is the right thing to do.
-
- If, instead, you use the GCC driver to create shared libraries,
- you may find that they will not always be linked with the shared
- `libgcc'. If GCC finds, at its configuration time, that you have
- a GNU linker that does not support option `--eh-frame-hdr', it
- will link the shared version of `libgcc' into shared libraries by
- default. Otherwise, it will take advantage of the linker and
- optimize away the linking with the shared version of `libgcc',
- linking with the static version of libgcc by default. This allows
- exceptions to propagate through such shared libraries, without
- incurring relocation costs at library load time.
-
- However, if a library or main executable is supposed to throw or
- catch exceptions, you must link it using the G++ or GCJ driver, as
- appropriate for the languages used in the program, or using the
- option `-shared-libgcc', such that it is linked with the shared
- `libgcc'.
-
-`-symbolic'
- Bind references to global symbols when building a shared object.
- Warn about any unresolved references (unless overridden by the
- link editor option `-Xlinker -z -Xlinker defs'). Only a few
- systems support this option.
-
-`-Xlinker OPTION'
- Pass OPTION as an option to the linker. You can use this to
- supply system-specific linker options which GCC does not know how
- to recognize.
-
- If you want to pass an option that takes an argument, you must use
- `-Xlinker' twice, once for the option and once for the argument.
- For example, to pass `-assert definitions', you must write
- `-Xlinker -assert -Xlinker definitions'. It does not work to write
- `-Xlinker "-assert definitions"', because this passes the entire
- string as a single argument, which is not what the linker expects.
-
-`-Wl,OPTION'
- Pass OPTION as an option to the linker. If OPTION contains
- commas, it is split into multiple options at the commas.
-
-`-u SYMBOL'
- Pretend the symbol SYMBOL is undefined, to force linking of
- library modules to define it. You can use `-u' multiple times with
- different symbols to force loading of additional library modules.
-
- ---------- Footnotes ----------
-
- (1) On some systems, `gcc -shared' needs to build supplementary stub
-code for constructors to work. On multi-libbed systems, `gcc -shared'
-must select the correct support libraries to link against. Failing to
-supply the correct flags may lead to subtle defects. Supplying them in
-cases where they are not necessary is innocuous.
-
-\1f
-File: gcc.info, Node: Directory Options, Next: Spec Files, Prev: Link Options, Up: Invoking GCC
-
-Options for Directory Search
-============================
-
- These options specify directories to search for header files, for
-libraries and for parts of the compiler:
-
-`-IDIR'
- Add the directory DIR to the head of the list of directories to be
- searched for header files. This can be used to override a system
- header file, substituting your own version, since these
- directories are searched before the system header file
- directories. However, you should not use this option to add
- directories that contain vendor-supplied system header files (use
- `-isystem' for that). If you use more than one `-I' option, the
- directories are scanned in left-to-right order; the standard
- system directories come after.
-
- If a standard system include directory, or a directory specified
- with `-isystem', is also specified with `-I', the `-I' option will
- be ignored. The directory will still be searched but as a system
- directory at its normal position in the system include chain.
- This is to ensure that GCC's procedure to fix buggy system headers
- and the ordering for the include_next directive are not
- inadvertantly changed. If you really need to change the search
- order for system directories, use the `-nostdinc' and/or
- `-isystem' options.
-
-`-I-'
- Any directories you specify with `-I' options before the `-I-'
- option are searched only for the case of `#include "FILE"'; they
- are not searched for `#include <FILE>'.
-
- If additional directories are specified with `-I' options after
- the `-I-', these directories are searched for all `#include'
- directives. (Ordinarily _all_ `-I' directories are used this way.)
-
- In addition, the `-I-' option inhibits the use of the current
- directory (where the current input file came from) as the first
- search directory for `#include "FILE"'. There is no way to
- override this effect of `-I-'. With `-I.' you can specify
- searching the directory which was current when the compiler was
- invoked. That is not exactly the same as what the preprocessor
- does by default, but it is often satisfactory.
-
- `-I-' does not inhibit the use of the standard system directories
- for header files. Thus, `-I-' and `-nostdinc' are independent.
-
-`-LDIR'
- Add directory DIR to the list of directories to be searched for
- `-l'.
-
-`-BPREFIX'
- This option specifies where to find the executables, libraries,
- include files, and data files of the compiler itself.
-
- The compiler driver program runs one or more of the subprograms
- `cpp', `cc1', `as' and `ld'. It tries PREFIX as a prefix for each
- program it tries to run, both with and without `MACHINE/VERSION/'
- (*note Target Options::).
-
- For each subprogram to be run, the compiler driver first tries the
- `-B' prefix, if any. If that name is not found, or if `-B' was
- not specified, the driver tries two standard prefixes, which are
- `/usr/lib/gcc/' and `/usr/local/lib/gcc-lib/'. If neither of
- those results in a file name that is found, the unmodified program
- name is searched for using the directories specified in your
- `PATH' environment variable.
-
- The compiler will check to see if the path provided by the `-B'
- refers to a directory, and if necessary it will add a directory
- separator character at the end of the path.
-
- `-B' prefixes that effectively specify directory names also apply
- to libraries in the linker, because the compiler translates these
- options into `-L' options for the linker. They also apply to
- includes files in the preprocessor, because the compiler
- translates these options into `-isystem' options for the
- preprocessor. In this case, the compiler appends `include' to the
- prefix.
-
- The run-time support file `libgcc.a' can also be searched for using
- the `-B' prefix, if needed. If it is not found there, the two
- standard prefixes above are tried, and that is all. The file is
- left out of the link if it is not found by those means.
-
- Another way to specify a prefix much like the `-B' prefix is to use
- the environment variable `GCC_EXEC_PREFIX'. *Note Environment
- Variables::.
-
- As a special kludge, if the path provided by `-B' is
- `[dir/]stageN/', where N is a number in the range 0 to 9, then it
- will be replaced by `[dir/]include'. This is to help with
- boot-strapping the compiler.
-
-`-specs=FILE'
- Process FILE after the compiler reads in the standard `specs'
- file, in order to override the defaults that the `gcc' driver
- program uses when determining what switches to pass to `cc1',
- `cc1plus', `as', `ld', etc. More than one `-specs=FILE' can be
- specified on the command line, and they are processed in order,
- from left to right.
-
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