gcc.1

早期freebsd实现

\&.o\c
\&\|', its assembler file in `\|\c
.B \c
.I source\c
\&.s\c
\&\|', and
all preprocessed C source on the standard output.
.TP
.B \-v
Print (on the standard error output) the commands executed to run the stages
of compilation.  Also print the version number of the compiler driver
program and of the preprocessor and the compiler proper.
.TP
.B \-pipe
Use pipes rather than temporary files for communication between the
various stages of compilation.  This fails to work on some systems where
the assembler cannot read from a pipe; but the GNU assembler has
no trouble.
.PP

.SH LANGUAGE OPTIONS
The following options control the dialect of C that the compiler
accepts:
.TP
.B \-ansi
.I
Support all ANSI standard C programs.  
.I

This turns off certain features of GNU C that are incompatible with
ANSI C, such as the \c
.B asm\c
\&, \c
.B inline\c
\& and \c
.B typeof\c
\&
keywords, and predefined macros such as \c
.B unix\c
\& and \c
.B vax\c
\&
that identify the type of system you are using.  It also enables the
undesirable and rarely used ANSI trigraph feature, and makes the
preprocessor accept `\|\c
.B $\c
\&\|' as part of identifiers.

The alternate keywords \c
.B __asm__\c
\&, \c
.B __extension__\c
\&,
\c
.B __inline__\c
\& and \c
.B __typeof__\c
\& continue to work despite
`\|\c
.B \-ansi\c
\&\|'.  You would not want to use them in an ANSI C program, of
course, but it is useful to put them in header files that might be included
in compilations done with `\|\c
.B \-ansi\c
\&\|'.  Alternate predefined macros
such as \c
.B __unix__\c
\& and \c
.B __vax__\c
\& are also available, with or
without `\|\c
.B \-ansi\c
\&\|'.

The `\|\c
.B \-ansi\c
\&\|' option does not cause non-ANSI programs to be
rejected gratuitously.  For that, `\|\c
.B \-pedantic\c
\&\|' is required in
addition to `\|\c
.B \-ansi\c
\&\|'.  

The preprocessor predefines a macro \c
.B __STRICT_ANSI__\c
\& when you use the `\|\c
.B \-ansi\c
\&\|'
option.  Some header files may notice this macro and refrain
from declaring certain functions or defining certain macros that the
ANSI standard doesn't call for; this is to avoid interfering with any
programs that might use these names for other things.
.TP
.B \-fno\-asm
Do not recognize \c
.B asm\c
\&, \c
.B inline\c
\& or \c
.B typeof\c
\& as a
keyword.  These words may then be used as identifiers.  You can
use \c
.B __asm__\c
\&, \c
.B __inline__\c
\& and \c
.B __typeof__\c
\& instead.
`\|\c
.B \-ansi\c
\&\|' implies `\|\c
.B \-fno\-asm\c
\&\|'.
.TP
.B \-fno\-builtin
.I (Ignored for C++.)
Don't recognize non-ANSI built-in functions.  `\|\c
.B \-ansi\c
\&\|' also has this
effect. Currently, the only function affected is 
.B alloca\c
\&.
.TP
.B \-fno\-strict\-prototype
.I
(C++ only.)
Consider the declaration \c
.B int foo ();\c
\&.  In C++, this means that the
function \c
.B foo\c
\& takes no arguments.  In ANSI C, this is declared
.B int foo(void);\c
\&.  With the flag `\|\c
.B \-fno\-strict\-prototype\c
\&\|',
declaring functions with no arguments is equivalent to declaring its
argument list to be untyped, i.e., \c
.B int foo ();\c
\& is equivalent to
saying \c
.B int foo (...);\c
\&.
.TP
.B \-trigraphs
Support ANSI C trigraphs.  The `\|\c
.B \-ansi\c
\&\|' option implies `\|\c
.B \-trigraphs\c
\&\|'.
.TP
.B \-traditional
Attempt to support some aspects of traditional C compilers.
For details, see the GNU C Manual; the duplicate list here
has been deleted so that we won't get complaints when it
is out of date.

But one note about C++ programs only (not C).  `\|\c
.B \-traditional\c
\&\|' has one additional effect for C++: assignment to 
.B this
is permitted.  This is the same as the effect of `\|\c
.B \-fthis\-is\-variable\c
\&\|'.
.TP
.B \-traditional\-cpp
Attempt to support some aspects of traditional C preprocessors.
This includes the items that specifically mention the preprocessor above,
but none of the other effects of `\|\c
.B \-traditional\c
\&\|'.
.TP
.B \-fdollars\-in\-identifiers
.I
(C++ only.)
Permit the use of `\|\c
.B $\c
\&\|' in identifiers.   (For GNU C, this is the default, and you can
forbid it with `\|\c
.B \-ansi\c
\&\|'.)
Traditional C allowed the character `\|\c
.B $\c
\&\|' to form part of identifiers; by default, GNU C also
allows this.  However, ANSI C forbids `\|\c
.B $\c
\&\|' in identifiers, and GNU C++ also forbids it by default on most
platforms (though on some platforms it's enabled by default for GNU
C++ as well).
.TP
.B \-fenum\-int\-equiv
.I
(C++ only.)
Normally GNU C++ allows conversion of 
.B enum
to
.B int\c
\&, but not the other way around.  Use this option if you want GNU C++
to allow conversion of
.B int
to 
.B enum
as well.  
.TP
.B \-fall\-virtual
.I
(C++ only.)
When you use the `\|\c
.B \-fall\-virtual\c
\&\|', all member functions
(except for constructor functions and new/delete member operators)
declared in the same class with a ``method-call'' operator method are
treated as virtual functions of the given class.  In effect, all
of these methods become ``implicitly virtual.''

This does \c
.I not\c
\& mean that all calls to these methods will be made through the
internal table of virtual functions.  There are some circumstances
under which it is obvious that a call to a given virtual function can
be made directly, and in these cases the calls still go direct.

The effect of making all methods of a class with a declared
\&`\|\c
.B
operator->()()\c
\&\|' implicitly virtual using `\|\c
.B \-fall\-virtual\c
\&\|' extends
also to all non-constructor methods of any class derived from such a
class.
.TP
.B \-fcond\-mismatch
Allow conditional expressions with mismatched types in the second and
third arguments.  The value of such an expression is void.
.TP
.B \-fthis\-is\-variable
.I
(C++ only.)
The incorporation of user-defined free store management into C++ has
made assignment to \c
.B this\c
\& an anachronism.  Therefore, by default GNU
C++ treats the type of \c
.B this\c
\& in a member function of \c
.B class X\c
\&
to be \c
.B X *const\c
\&.  In other words, it is illegal to assign to
\c
.B this\c
\& within a class member function.  However, for backwards
compatibility, you can invoke the old behavior by using
\&`\|\c
.B \-fthis\-is\-variable\c
\&\|'.
.TP
.B \-funsigned\-char
Let the type \c
.B char\c
\& be unsigned, like \c
.B unsigned char\c
\&.

Each kind of machine has a default for what \c
.B char\c
\& should
be.  It is either like \c
.B unsigned char\c
\& by default or like
\c
.B signed char\c
\& by default.

Ideally, a portable program should always use \c
.B signed char\c
\& or
\c
.B unsigned char\c
\& when it depends on the signedness of an object.
But many programs have been written to use plain \c
.B char\c
\& and
expect it to be signed, or expect it to be unsigned, depending on the
machines they were written for.  This option, and its inverse, let you
make such a program work with the opposite default.

The type \c
.B char\c
\& is always a distinct type from each of
\c
.B signed char\c
\& and \c
.B unsigned char\c
\&, even though its behavior
is always just like one of those two.

.TP
.B \-fsigned\-char
Let the type \c
.B char\c
\& be signed, like \c
.B signed char\c
\&.

Note that this is equivalent to `\|\c
.B \-fno\-unsigned\-char\c
\&\|', which is
the negative form of `\|\c
.B \-funsigned\-char\c
\&\|'.  Likewise,
`\|\c
.B \-fno\-signed\-char\c
\&\|' is equivalent to `\|\c
.B \-funsigned\-char\c
\&\|'.
.TP
.B \-fsigned\-bitfields
.TP
.B \-funsigned\-bitfields
.TP
.B \-fno\-signed\-bitfields
.TP
.B \-fno\-unsigned\-bitfields
These options control whether a bitfield is
signed or unsigned, when declared with no explicit `\|\c
.B signed\c
\&\|' or `\|\c
.B unsigned\c
\&\|' qualifier.  By default, such a bitfield is
signed, because this is consistent: the basic integer types such as
\c
.B int\c
\& are signed types.

However, when you specify `\|\c
.B \-traditional\c
\&\|', bitfields are all unsigned
no matter what.
.TP
.B \-fwritable\-strings
Store string constants in the writable data segment and don't uniquize
them.  This is for compatibility with old programs which assume they
can write into string constants.  `\|\c
.B \-traditional\c
\&\|' also has this
effect.

Writing into string constants is a very bad idea; ``constants'' should
be constant.
.PP

.SH PREPROCESSOR OPTIONS
These options control the C preprocessor, which is run on each C source
file before actual compilation.

If you use the `\|\c
.B \-E\c
\&\|' option, GCC does nothing except preprocessing.
Some of these options make sense only together with `\|\c
.B \-E\c
\&\|' because
they cause the preprocessor output to be unsuitable for actual
compilation.
.TP
.BI "\-i " file\c
\&
Process \c
.I file\c
\& as input, discarding the resulting output, before
processing the regular input file.  Because the output generated from
\c
.I file\c
\& is discarded, the only effect of `\|\c
.B \-i \c
.I file\c
\&\c
\&\|' is to
make the macros defined in \c
.I file\c
\& available for use in the main
input.  The preprocessor evaluates any `\|\c
.B \-D\c
\&\|' and `\|\c
.B \-U\c
\&\|' options
on the command line before processing `\|\c
.B \-i\c
\&\|' \c
.I file\c
\&.
.TP
.B \-nostdinc
Do not search the standard system directories for header files.  Only
the directories you have specified with `\|\c
.B \-I\c
\&\|' options (and the
current directory, if appropriate) are searched.   

By using both `\|\c
.B \-nostdinc\c
\&\|' and `\|\c
.B \-I\-\c
\&\|', you can limit the include-file search file to only those
directories you specify explicitly.
.TP
.B \-undef
Do not predefine any nonstandard macros.  (Including architecture flags).
.TP
.B \-E
Run only the C preprocessor.  Preprocess all the C source files
specified and output the results to the standard output or to the
specified output file.
.TP
.B \-C
Tell the preprocessor not to discard comments.  Used with the
`\|\c
.B \-E\c
\&\|' option.
.TP
.B \-P
Tell the preprocessor not to generate `\|\c
.B #line\c
\&\|' commands.
Used with the `\|\c
.B \-E\c
\&\|' option.
.TP
.B \-M
Tell the preprocessor to output a rule suitable for \c
.B make\c
\&
describing the dependencies of each object file.  For each source file,
the preprocessor outputs one \c
.B make\c
\&-rule whose target is the object
file name for that source file and whose dependencies are all the files
`\|\c
.B #include\c
\&\|'d in it.  This rule may be a single line or may be
continued with `\|\c
.B \e\c
\&\|newline if it is long.  The list of rules is
printed on the standard output instead of the preprocessed C program.

`\|\c
.B \-M\c
\&\|' implies `\|\c
.B \-E\c
\&\|'.
.TP
.B \-MM
Like `\|\c
.B \-M\c
\&\|' but the output mentions only the user header files
included with `\|\c
.B #include "\c
.I file\c
\&"\c
\&\|'.  System header files
included with `\|\c
.B #include <\c
.I file\c
\&>\c
\&\|' are omitted.
.TP
.B \-MD
Like `\|\c
.B \-M\c
\&\|' but the dependency information is written to files with
names made by replacing `\|\c
.B .c\c
\&\|' with `\|\c
.B .d\c
\&\|' at the end of the
input file names.  This is in addition to compiling the file as
specified\(em\&`\|\c
.B \-MD\c
\&\|' does not inhibit ordinary compilation the way
`\|\c
.B \-M\c
\&\|' does.

The Mach utility `\|\c
.B md\c
\&\|' can be used to merge the `\|\c
.B .d\c
\&\|' files
into a single dependency file suitable for using with the `\|\c
.B make\c
\&\|'
command.
.TP
.B \-MMD
Like `\|\c
.B \-MD\c
\&\|' except mention only user header files, not system
header files.
.TP
.B \-H
Print the name of each header file used, in addition to other normal
activities.
.TP
.BI \-D macro
Define macro \c
.I macro\c
\& with the string `\|\c
.B 1\c
\&\|' as its definition.
.TP
.BI \-D macro = defn
Define macro \c
.I macro\c
\& as \c
.I defn\c
\&.    All instances of `\|\c
.B \-D\c
\&\|' on
the command line are processed before any `\|\c
.B \-U\c
\&\|' or `\|\c
.B \-i\c
\&\|' options.
.TP
.BI \-U macro
Undefine macro \c
.I macro\c
\&.  `\|\c
.B \-U\c
\&\|' options are evaluated after all `\|\c
.B \-D\c
\&\|' options, but before any `\|\c
.B \-i\c
\&\|' options.
.TP
.B \-dM
Tell the preprocessor to output only a list of the macro definitions
that are in effect at the end of preprocessing.  Used with the `\|\c
.B \-E\c
\&\|'
option.
.TP
.B \-dD
Tell the preprocessing to pass all macro definitions into the output, in
their proper sequence in the rest of the output.
.TP
.B \-dN
Like `\|\c
.B \-dD\c