svn commit: r233099 - in stable/9: . gnu/usr.bin/cc/c++ gnu/usr.bin/cc/cc gnu/usr.bin/cc/cpp share/man/man5 share/mk sys/conf tools/build/options usr.bin/clang/clang

Dimitry Andric dim at FreeBSD.org
Sat Mar 17 22:29:06 UTC 2012


Author: dim
Date: Sat Mar 17 22:29:05 2012
New Revision: 233099
URL: http://svn.freebsd.org/changeset/base/233099

Log:
  MFC 232322:
    Add a WITH_CLANG_IS_CC option for src.conf(5), disabled by default, that
    installs clang as /usr/bin/cc, /usr/bin/c++ and /usr/bin/cpp.
  
    Note this does *not* disable building and installing gcc, which will
    still be available as /usr/bin/gcc, /usr/bin/g++ and /usr/bin/gcpp.  If
    you want to disable gcc completely, you must use WITHOUT_GCC.
  
  MFC 232323:
    Regenerate src.conf(5) after r232322.
  
  MFC 232477:
    In r232322, I forgot one case where a check for MK_CLANG_IS_CC was
    needed, in sys/conf/kern.pre.mk.  Add it now.
  
  MFC 232522:
    Fix a thinko in r232322, where gcc (and its tools) are not built during
    the cross-tools stage, if CC=clang and WITH_CLANG_IS_CC is not set.
  
    This causes no 'cc' to be installed in the temporary cross-tools tree,
    making lint fall over later in the build, because it ignores ${CC} and
    attempts to run 'cc' anyway.
  
    To fix this, only skip building gcc during cross-tools, if WITHOUT_GCC
    is set, or if WITH_CLANG_IS_CC is set.
  
    Pointy hat to:	dim

Added:
  stable/9/gnu/usr.bin/cc/cpp/gcpp.1
     - copied unchanged from r232322, head/gnu/usr.bin/cc/cpp/gcpp.1
  stable/9/tools/build/options/WITH_CLANG_IS_CC
     - copied unchanged from r232322, head/tools/build/options/WITH_CLANG_IS_CC
Modified:
  stable/9/Makefile.inc1   (contents, props changed)
  stable/9/gnu/usr.bin/cc/c++/Makefile
  stable/9/gnu/usr.bin/cc/cc/Makefile
  stable/9/gnu/usr.bin/cc/cpp/Makefile
  stable/9/share/man/man5/src.conf.5
  stable/9/share/mk/bsd.own.mk
  stable/9/share/mk/bsd.sys.mk
  stable/9/sys/conf/kern.mk
  stable/9/sys/conf/kern.pre.mk
  stable/9/sys/conf/kmod.mk
  stable/9/usr.bin/clang/clang/Makefile
Directory Properties:
  stable/9/share/man/   (props changed)
  stable/9/share/man/man5/   (props changed)
  stable/9/share/mk/   (props changed)
  stable/9/sys/   (props changed)
  stable/9/sys/conf/   (props changed)
  stable/9/tools/   (props changed)
  stable/9/tools/build/options/   (props changed)
  stable/9/usr.bin/   (props changed)
  stable/9/usr.bin/clang/   (props changed)

Modified: stable/9/Makefile.inc1
==============================================================================
--- stable/9/Makefile.inc1	Sat Mar 17 22:12:09 2012	(r233098)
+++ stable/9/Makefile.inc1	Sat Mar 17 22:29:05 2012	(r233099)
@@ -1103,6 +1103,10 @@ _aicasm= sys/modules/aic7xxx/aicasm
 _share=	share/syscons/scrnmaps
 .endif
 
+.if ${MK_GCC} != "no" && ${MK_CLANG_IS_CC} == "no"
+_gcc_tools= gnu/usr.bin/cc/cc_tools
+.endif
+
 .if ${MK_KERBEROS} != "no"
 _kerberos5_tools= kerberos5/tools
 .endif
@@ -1131,7 +1135,7 @@ build-tools:
 		${MAKE} DIRPRFX=${_tool}/ build-tools
 .endfor
 .for _tool in \
-    gnu/usr.bin/cc/cc_tools \
+    ${_gcc_tools} \
     ${_kerberos5_tools}
 	${_+_}@${ECHODIR} "===> ${_tool} (obj,depend,all)"; \
 		cd ${.CURDIR}/${_tool}; \
@@ -1161,14 +1165,12 @@ _kgzip=		usr.sbin/kgzip
 _binutils=	gnu/usr.bin/binutils
 .endif
 
-.if ${MK_CLANG} != "no"
-.if ${CC:T:Mclang} == "clang"
+.if ${MK_CLANG} != "no" && (${MK_CLANG_IS_CC} != "no" || ${CC:T:Mclang} == "clang")
 _clang=		usr.bin/clang
 _clang_libs=	lib/clang
 .endif
-.endif
 
-.if ${MK_GCC} != "no"
+.if ${MK_GCC} != "no" && ${MK_CLANG_IS_CC} == "no"
 _cc=		gnu/usr.bin/cc
 .endif
 

Modified: stable/9/gnu/usr.bin/cc/c++/Makefile
==============================================================================
--- stable/9/gnu/usr.bin/cc/c++/Makefile	Sat Mar 17 22:12:09 2012	(r233098)
+++ stable/9/gnu/usr.bin/cc/c++/Makefile	Sat Mar 17 22:29:05 2012	(r233099)
@@ -1,14 +1,18 @@
 # $FreeBSD$
 
+.include <bsd.own.mk>
+
 .include "../Makefile.inc"
 .include "../Makefile.fe"
 
 .PATH: ${GCCDIR}/cp
 
-PROG=	c++
+PROG=	g++
 SRCS+=	g++spec.c
-LINKS=	${BINDIR}/c++ ${BINDIR}/g++
-LINKS+=	${BINDIR}/c++ ${BINDIR}/CC
+.if ${MK_CLANG_IS_CC} == "no"
+LINKS=	${BINDIR}/g++ ${BINDIR}/c++
+LINKS+=	${BINDIR}/g++ ${BINDIR}/CC
+.endif
 NO_MAN=
 
 DPADD=	${LIBCPP} ${LIBIBERTY}

Modified: stable/9/gnu/usr.bin/cc/cc/Makefile
==============================================================================
--- stable/9/gnu/usr.bin/cc/cc/Makefile	Sat Mar 17 22:12:09 2012	(r233098)
+++ stable/9/gnu/usr.bin/cc/cc/Makefile	Sat Mar 17 22:29:05 2012	(r233099)
@@ -1,15 +1,20 @@
 # $FreeBSD$
 
+.include <bsd.own.mk>
+
 .include "../Makefile.inc"
 .include "../Makefile.fe"
 
-PROG=	cc
+PROG=	gcc
 MAN=	gcc.1
 SRCS+=  gccspec.c
 
 NO_SHARED?=yes
 
-LINKS=	${BINDIR}/cc ${BINDIR}/gcc
-MLINKS=	gcc.1 cc.1 gcc.1 c++.1 gcc.1 g++.1 gcc.1 CC.1
+MLINKS=	gcc.1 g++.1
+.if ${MK_CLANG_IS_CC} == "no"
+LINKS=	${BINDIR}/gcc ${BINDIR}/cc
+MLINKS+= gcc.1 cc.1 gcc.1 c++.1 gcc.1 CC.1
+.endif
 
 .include <bsd.prog.mk>

Modified: stable/9/gnu/usr.bin/cc/cpp/Makefile
==============================================================================
--- stable/9/gnu/usr.bin/cc/cpp/Makefile	Sat Mar 17 22:12:09 2012	(r233098)
+++ stable/9/gnu/usr.bin/cc/cpp/Makefile	Sat Mar 17 22:29:05 2012	(r233099)
@@ -1,10 +1,16 @@
 # $FreeBSD$
 
+.include <bsd.own.mk>
 
 .include "../Makefile.inc"
 .include "../Makefile.fe"
 
-PROG=	cpp
+PROG=	gcpp
 SRCS+=	cppspec.c
 
+.if ${MK_CLANG_IS_CC} == "no"
+LINKS=	${BINDIR}/gcpp ${BINDIR}/cpp
+MLINKS=	gcpp.1 cpp.1
+.endif
+
 .include <bsd.prog.mk>

Copied: stable/9/gnu/usr.bin/cc/cpp/gcpp.1 (from r232322, head/gnu/usr.bin/cc/cpp/gcpp.1)
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ stable/9/gnu/usr.bin/cc/cpp/gcpp.1	Sat Mar 17 22:29:05 2012	(r233099, copy of r232322, head/gnu/usr.bin/cc/cpp/gcpp.1)
@@ -0,0 +1,929 @@
+.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.14
+.\"
+.\" Standard preamble:
+.\" ========================================================================
+.de Sh \" Subsection heading
+.br
+.if t .Sp
+.ne 5
+.PP
+\fB\\$1\fR
+.PP
+..
+.de Sp \" Vertical space (when we can't use .PP)
+.if t .sp .5v
+.if n .sp
+..
+.de Vb \" Begin verbatim text
+.ft CW
+.nf
+.ne \\$1
+..
+.de Ve \" End verbatim text
+.ft R
+.fi
+..
+.\" Set up some character translations and predefined strings.  \*(-- will
+.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
+.\" double quote, and \*(R" will give a right double quote.  | will give a
+.\" real vertical bar.  \*(C+ will give a nicer C++.  Capital omega is used to
+.\" do unbreakable dashes and therefore won't be available.  \*(C` and \*(C'
+.\" expand to `' in nroff, nothing in troff, for use with C<>.
+.tr \(*W-|\(bv\*(Tr
+.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
+.ie n \{\
+.    ds -- \(*W-
+.    ds PI pi
+.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
+.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
+.    ds L" ""
+.    ds R" ""
+.    ds C` ""
+.    ds C' ""
+'br\}
+.el\{\
+.    ds -- \|\(em\|
+.    ds PI \(*p
+.    ds L" ``
+.    ds R" ''
+'br\}
+.\"
+.\" If the F register is turned on, we'll generate index entries on stderr for
+.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
+.\" entries marked with X<> in POD.  Of course, you'll have to process the
+.\" output yourself in some meaningful fashion.
+.if \nF \{\
+.    de IX
+.    tm Index:\\$1\t\\n%\t"\\$2"
+..
+.    nr % 0
+.    rr F
+.\}
+.\"
+.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
+.\" way too many mistakes in technical documents.
+.hy 0
+.if n .na
+.\"
+.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
+.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
+.    \" fudge factors for nroff and troff
+.if n \{\
+.    ds #H 0
+.    ds #V .8m
+.    ds #F .3m
+.    ds #[ \f1
+.    ds #] \fP
+.\}
+.if t \{\
+.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
+.    ds #V .6m
+.    ds #F 0
+.    ds #[ \&
+.    ds #] \&
+.\}
+.    \" simple accents for nroff and troff
+.if n \{\
+.    ds ' \&
+.    ds ` \&
+.    ds ^ \&
+.    ds , \&
+.    ds ~ ~
+.    ds /
+.\}
+.if t \{\
+.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
+.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
+.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
+.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
+.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
+.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
+.\}
+.    \" troff and (daisy-wheel) nroff accents
+.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
+.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
+.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
+.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
+.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
+.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
+.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
+.ds ae a\h'-(\w'a'u*4/10)'e
+.ds Ae A\h'-(\w'A'u*4/10)'E
+.    \" corrections for vroff
+.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
+.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
+.    \" for low resolution devices (crt and lpr)
+.if \n(.H>23 .if \n(.V>19 \
+\{\
+.    ds : e
+.    ds 8 ss
+.    ds o a
+.    ds d- d\h'-1'\(ga
+.    ds D- D\h'-1'\(hy
+.    ds th \o'bp'
+.    ds Th \o'LP'
+.    ds ae ae
+.    ds Ae AE
+.\}
+.rm #[ #] #H #V #F C
+.\" ========================================================================
+.\"
+.IX Title "CPP 1"
+.TH CPP 1 "2007-07-19" "gcc-4.2.1" "GNU"
+.SH "NAME"
+cpp \- The C Preprocessor
+.SH "SYNOPSIS"
+.IX Header "SYNOPSIS"
+cpp [\fB\-D\fR\fImacro\fR[=\fIdefn\fR]...] [\fB\-U\fR\fImacro\fR]
+    [\fB\-I\fR\fIdir\fR...] [\fB\-iquote\fR\fIdir\fR...]
+    [\fB\-W\fR\fIwarn\fR...]
+    [\fB\-M\fR|\fB\-MM\fR] [\fB\-MG\fR] [\fB\-MF\fR \fIfilename\fR]
+    [\fB\-MP\fR] [\fB\-MQ\fR \fItarget\fR...]
+    [\fB\-MT\fR \fItarget\fR...]
+    [\fB\-P\fR] [\fB\-fno\-working\-directory\fR]
+    [\fB\-x\fR \fIlanguage\fR] [\fB\-std=\fR\fIstandard\fR]
+    \fIinfile\fR \fIoutfile\fR
+.PP
+Only the most useful options are listed here; see below for the remainder.
+.SH "DESCRIPTION"
+.IX Header "DESCRIPTION"
+The C preprocessor, often known as \fIcpp\fR, is a \fImacro processor\fR
+that is used automatically by the C compiler to transform your program
+before compilation.  It is called a macro processor because it allows
+you to define \fImacros\fR, which are brief abbreviations for longer
+constructs.
+.PP
+The C preprocessor is intended to be used only with C and \*(C+ source
+code.  In the past, it has been abused as a general text processor.  It
+will choke on input which does not obey C's lexical rules.  For
+example, apostrophes will be interpreted as the beginning of character
+constants, and cause errors.  Also, you cannot rely on it preserving
+characteristics of the input which are not significant to C\-family
+languages.  If a Makefile is preprocessed, all the hard tabs will be
+removed, and the Makefile will not work.
+.PP
+Having said that, you can often get away with using cpp on things which
+are not C.  Other Algol-ish programming languages are often safe
+(Pascal, Ada, etc.) So is assembly, with caution.  \fB\-traditional\-cpp\fR
+mode preserves more white space, and is otherwise more permissive.  Many
+of the problems can be avoided by writing C or \*(C+ style comments
+instead of native language comments, and keeping macros simple.
+.PP
+Wherever possible, you should use a preprocessor geared to the language
+you are writing in.  Modern versions of the \s-1GNU\s0 assembler have macro
+facilities.  Most high level programming languages have their own
+conditional compilation and inclusion mechanism.  If all else fails,
+try a true general text processor, such as \s-1GNU\s0 M4.
+.PP
+C preprocessors vary in some details.  This manual discusses the \s-1GNU\s0 C
+preprocessor, which provides a small superset of the features of \s-1ISO\s0
+Standard C.  In its default mode, the \s-1GNU\s0 C preprocessor does not do a
+few things required by the standard.  These are features which are
+rarely, if ever, used, and may cause surprising changes to the meaning
+of a program which does not expect them.  To get strict \s-1ISO\s0 Standard C,
+you should use the \fB\-std=c89\fR or \fB\-std=c99\fR options, depending
+on which version of the standard you want.  To get all the mandatory
+diagnostics, you must also use \fB\-pedantic\fR.  
+.PP
+This manual describes the behavior of the \s-1ISO\s0 preprocessor.  To
+minimize gratuitous differences, where the \s-1ISO\s0 preprocessor's
+behavior does not conflict with traditional semantics, the
+traditional preprocessor should behave the same way.  The various
+differences that do exist are detailed in the section \fBTraditional
+Mode\fR.
+.PP
+For clarity, unless noted otherwise, references to \fB\s-1CPP\s0\fR in this
+manual refer to \s-1GNU\s0 \s-1CPP\s0.
+.SH "OPTIONS"
+.IX Header "OPTIONS"
+The C preprocessor expects two file names as arguments, \fIinfile\fR and
+\&\fIoutfile\fR.  The preprocessor reads \fIinfile\fR together with any
+other files it specifies with \fB#include\fR.  All the output generated
+by the combined input files is written in \fIoutfile\fR.
+.PP
+Either \fIinfile\fR or \fIoutfile\fR may be \fB\-\fR, which as
+\&\fIinfile\fR means to read from standard input and as \fIoutfile\fR
+means to write to standard output.  Also, if either file is omitted, it
+means the same as if \fB\-\fR had been specified for that file.
+.PP
+Unless otherwise noted, or the option ends in \fB=\fR, all options
+which take an argument may have that argument appear either immediately
+after the option, or with a space between option and argument:
+\&\fB\-Ifoo\fR and \fB\-I foo\fR have the same effect.
+.PP
+Many options have multi-letter names; therefore multiple single-letter
+options may \fInot\fR be grouped: \fB\-dM\fR is very different from
+\&\fB\-d\ \-M\fR.
+.IP "\fB\-D\fR \fIname\fR" 4
+.IX Item "-D name"
+Predefine \fIname\fR as a macro, with definition \f(CW1\fR.
+.IP "\fB\-D\fR \fIname\fR\fB=\fR\fIdefinition\fR" 4
+.IX Item "-D name=definition"
+The contents of \fIdefinition\fR are tokenized and processed as if
+they appeared during translation phase three in a \fB#define\fR
+directive.  In particular, the definition will be truncated by
+embedded newline characters.
+.Sp
+If you are invoking the preprocessor from a shell or shell-like
+program you may need to use the shell's quoting syntax to protect
+characters such as spaces that have a meaning in the shell syntax.
+.Sp
+If you wish to define a function-like macro on the command line, write
+its argument list with surrounding parentheses before the equals sign
+(if any).  Parentheses are meaningful to most shells, so you will need
+to quote the option.  With \fBsh\fR and \fBcsh\fR,
+\&\fB\-D'\fR\fIname\fR\fB(\fR\fIargs...\fR\fB)=\fR\fIdefinition\fR\fB'\fR works.
+.Sp
+\&\fB\-D\fR and \fB\-U\fR options are processed in the order they
+are given on the command line.  All \fB\-imacros\fR \fIfile\fR and
+\&\fB\-include\fR \fIfile\fR options are processed after all
+\&\fB\-D\fR and \fB\-U\fR options.
+.IP "\fB\-U\fR \fIname\fR" 4
+.IX Item "-U name"
+Cancel any previous definition of \fIname\fR, either built in or
+provided with a \fB\-D\fR option.
+.IP "\fB\-undef\fR" 4
+.IX Item "-undef"
+Do not predefine any system-specific or GCC-specific macros.  The
+standard predefined macros remain defined.
+.IP "\fB\-I\fR \fIdir\fR" 4
+.IX Item "-I dir"
+Add the directory \fIdir\fR to the list of directories to be searched
+for header files.
+.Sp
+Directories named by \fB\-I\fR are searched before the standard
+system include directories.  If the directory \fIdir\fR is a standard
+system include directory, the option is ignored to ensure that the
+default search order for system directories and the special treatment
+of system headers are not defeated
+\&.
+.IP "\fB\-o\fR \fIfile\fR" 4
+.IX Item "-o file"
+Write output to \fIfile\fR.  This is the same as specifying \fIfile\fR
+as the second non-option argument to \fBcpp\fR.  \fBgcc\fR has a
+different interpretation of a second non-option argument, so you must
+use \fB\-o\fR to specify the output file.
+.IP "\fB\-Wall\fR" 4
+.IX Item "-Wall"
+Turns on all optional warnings which are desirable for normal code.
+At present this is \fB\-Wcomment\fR, \fB\-Wtrigraphs\fR,
+\&\fB\-Wmultichar\fR and a warning about integer promotion causing a
+change of sign in \f(CW\*(C`#if\*(C'\fR expressions.  Note that many of the
+preprocessor's warnings are on by default and have no options to
+control them.
+.IP "\fB\-Wcomment\fR" 4
+.IX Item "-Wcomment"
+.PD 0
+.IP "\fB\-Wcomments\fR" 4
+.IX Item "-Wcomments"
+.PD
+Warn whenever a comment-start sequence \fB/*\fR appears in a \fB/*\fR
+comment, or whenever a backslash-newline appears in a \fB//\fR comment.
+(Both forms have the same effect.)
+.IP "\fB\-Wtrigraphs\fR" 4
+.IX Item "-Wtrigraphs"
+Most trigraphs in comments cannot affect the meaning of the program.
+However, a trigraph that would form an escaped newline (\fB??/\fR at
+the end of a line) can, by changing where the comment begins or ends.
+Therefore, only trigraphs that would form escaped newlines produce
+warnings inside a comment.
+.Sp
+This option is implied by \fB\-Wall\fR.  If \fB\-Wall\fR is not
+given, this option is still enabled unless trigraphs are enabled.  To
+get trigraph conversion without warnings, but get the other
+\&\fB\-Wall\fR warnings, use \fB\-trigraphs \-Wall \-Wno\-trigraphs\fR.
+.IP "\fB\-Wtraditional\fR" 4
+.IX Item "-Wtraditional"
+Warn about certain constructs that behave differently in traditional and
+\&\s-1ISO\s0 C.  Also warn about \s-1ISO\s0 C constructs that have no traditional C
+equivalent, and problematic constructs which should be avoided.
+.IP "\fB\-Wimport\fR" 4
+.IX Item "-Wimport"
+Warn the first time \fB#import\fR is used.
+.IP "\fB\-Wundef\fR" 4
+.IX Item "-Wundef"
+Warn whenever an identifier which is not a macro is encountered in an
+\&\fB#if\fR directive, outside of \fBdefined\fR.  Such identifiers are
+replaced with zero.
+.IP "\fB\-Wunused\-macros\fR" 4
+.IX Item "-Wunused-macros"
+Warn about macros defined in the main file that are unused.  A macro
+is \fIused\fR if it is expanded or tested for existence at least once.
+The preprocessor will also warn if the macro has not been used at the
+time it is redefined or undefined.
+.Sp
+Built-in macros, macros defined on the command line, and macros
+defined in include files are not warned about.
+.Sp
+\&\fINote:\fR If a macro is actually used, but only used in skipped
+conditional blocks, then \s-1CPP\s0 will report it as unused.  To avoid the
+warning in such a case, you might improve the scope of the macro's
+definition by, for example, moving it into the first skipped block.
+Alternatively, you could provide a dummy use with something like:
+.Sp
+.Vb 2
+\&        #if defined the_macro_causing_the_warning
+\&        #endif
+.Ve
+.IP "\fB\-Wendif\-labels\fR" 4
+.IX Item "-Wendif-labels"
+Warn whenever an \fB#else\fR or an \fB#endif\fR are followed by text.
+This usually happens in code of the form
+.Sp
+.Vb 5
+\&        #if FOO
+\&        ...
+\&        #else FOO
+\&        ...
+\&        #endif FOO
+.Ve
+.Sp
+The second and third \f(CW\*(C`FOO\*(C'\fR should be in comments, but often are not
+in older programs.  This warning is on by default.
+.IP "\fB\-Werror\fR" 4
+.IX Item "-Werror"
+Make all warnings into hard errors.  Source code which triggers warnings
+will be rejected.
+.IP "\fB\-Wsystem\-headers\fR" 4
+.IX Item "-Wsystem-headers"
+Issue warnings for code in system headers.  These are normally unhelpful
+in finding bugs in your own code, therefore suppressed.  If you are
+responsible for the system library, you may want to see them.
+.IP "\fB\-w\fR" 4
+.IX Item "-w"
+Suppress all warnings, including those which \s-1GNU\s0 \s-1CPP\s0 issues by default.
+.IP "\fB\-pedantic\fR" 4
+.IX Item "-pedantic"
+Issue all the mandatory diagnostics listed in the C standard.  Some of
+them are left out by default, since they trigger frequently on harmless
+code.
+.IP "\fB\-pedantic\-errors\fR" 4
+.IX Item "-pedantic-errors"
+Issue all the mandatory diagnostics, and make all mandatory diagnostics
+into errors.  This includes mandatory diagnostics that \s-1GCC\s0 issues
+without \fB\-pedantic\fR but treats as warnings.
+.IP "\fB\-M\fR" 4
+.IX Item "-M"
+Instead of outputting the result of preprocessing, output a rule
+suitable for \fBmake\fR describing the dependencies of the main
+source file.  The preprocessor outputs one \fBmake\fR rule containing
+the object file name for that source file, a colon, and the names of all
+the included files, including those coming from \fB\-include\fR or
+\&\fB\-imacros\fR command line options.
+.Sp
+Unless specified explicitly (with \fB\-MT\fR or \fB\-MQ\fR), the
+object file name consists of the 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 \fB\e\fR\-newline.
+The rule has no commands.
+.Sp
+This option does not suppress the preprocessor's debug output, such as
+\&\fB\-dM\fR.  To avoid mixing such debug output with the dependency
+rules you should explicitly specify the dependency output file with
+\&\fB\-MF\fR, or use an environment variable like
+\&\fB\s-1DEPENDENCIES_OUTPUT\s0\fR.  Debug output
+will still be sent to the regular output stream as normal.
+.Sp
+Passing \fB\-M\fR to the driver implies \fB\-E\fR, and suppresses
+warnings with an implicit \fB\-w\fR.
+.IP "\fB\-MM\fR" 4
+.IX Item "-MM"
+Like \fB\-M\fR but do not mention header files that are found in
+system header directories, nor header files that are included,
+directly or indirectly, from such a header.
+.Sp
+This implies that the choice of angle brackets or double quotes in an
+\&\fB#include\fR directive does not in itself determine whether that
+header will appear in \fB\-MM\fR dependency output.  This is a
+slight change in semantics from \s-1GCC\s0 versions 3.0 and earlier.
+.IP "\fB\-MF\fR \fIfile\fR" 4
+.IX Item "-MF file"
+When used with \fB\-M\fR or \fB\-MM\fR, specifies a
+file to write the dependencies to.  If no \fB\-MF\fR switch is given
+the preprocessor sends the rules to the same place it would have sent
+preprocessed output.
+.Sp
+When used with the driver options \fB\-MD\fR or \fB\-MMD\fR,
+\&\fB\-MF\fR overrides the default dependency output file.
+.IP "\fB\-MG\fR" 4
+.IX Item "-MG"
+In conjunction with an option such as \fB\-M\fR requesting
+dependency generation, \fB\-MG\fR assumes missing header files are
+generated files and adds them to the dependency list without raising
+an error.  The dependency filename is taken directly from the
+\&\f(CW\*(C`#include\*(C'\fR directive without prepending any path.  \fB\-MG\fR
+also suppresses preprocessed output, as a missing header file renders
+this useless.
+.Sp
+This feature is used in automatic updating of makefiles.
+.IP "\fB\-MP\fR" 4
+.IX Item "-MP"
+This option instructs \s-1CPP\s0 to add a phony target for each dependency
+other than the main file, causing each to depend on nothing.  These
+dummy rules work around errors \fBmake\fR gives if you remove header
+files without updating the \fIMakefile\fR to match.
+.Sp
+This is typical output:
+.Sp
+.Vb 1
+\&        test.o: test.c test.h
+.Ve
+.Sp
+.Vb 1
+\&        test.h:
+.Ve
+.IP "\fB\-MT\fR \fItarget\fR" 4
+.IX Item "-MT target"
+Change the target of the rule emitted by dependency generation.  By
+default \s-1CPP\s0 takes the name of the main input file, including any path,
+deletes any file suffix such as \fB.c\fR, and appends the platform's
+usual object suffix.  The result is the target.
+.Sp
+An \fB\-MT\fR option will set the target to be exactly the string you
+specify.  If you want multiple targets, you can specify them as a single
+argument to \fB\-MT\fR, or use multiple \fB\-MT\fR options.
+.Sp
+For example, \fB\-MT\ '$(objpfx)foo.o'\fR might give
+.Sp
+.Vb 1
+\&        $(objpfx)foo.o: foo.c
+.Ve
+.IP "\fB\-MQ\fR \fItarget\fR" 4
+.IX Item "-MQ target"
+Same as \fB\-MT\fR, but it quotes any characters which are special to
+Make.  \fB\-MQ\ '$(objpfx)foo.o'\fR gives
+.Sp
+.Vb 1
+\&        $$(objpfx)foo.o: foo.c
+.Ve
+.Sp
+The default target is automatically quoted, as if it were given with
+\&\fB\-MQ\fR.
+.IP "\fB\-MD\fR" 4
+.IX Item "-MD"
+\&\fB\-MD\fR is equivalent to \fB\-M \-MF\fR \fIfile\fR, except that
+\&\fB\-E\fR is not implied.  The driver determines \fIfile\fR based on
+whether an \fB\-o\fR option is given.  If it is, the driver uses its
+argument but with a suffix of \fI.d\fR, otherwise it take the
+basename of the input file and applies a \fI.d\fR suffix.
+.Sp
+If \fB\-MD\fR is used in conjunction with \fB\-E\fR, any
+\&\fB\-o\fR switch is understood to specify the dependency output file, but if used without \fB\-E\fR, each \fB\-o\fR
+is understood to specify a target object file.
+.Sp
+Since \fB\-E\fR is not implied, \fB\-MD\fR can be used to generate
+a dependency output file as a side-effect of the compilation process.
+.IP "\fB\-MMD\fR" 4
+.IX Item "-MMD"
+Like \fB\-MD\fR except mention only user header files, not system
+header files.
+.IP "\fB\-x c\fR" 4
+.IX Item "-x c"
+.PD 0
+.IP "\fB\-x c++\fR" 4
+.IX Item "-x c++"
+.IP "\fB\-x assembler-with-cpp\fR" 4
+.IX Item "-x assembler-with-cpp"
+.PD
+Specify the source language: C, \*(C+, or assembly.  This has nothing
+to do with standards conformance or extensions; it merely selects which
+base syntax to expect.  If you give none of these options, cpp will
+deduce the language from the extension of the source file: \&\fB.c\fR,
+\fB.cc\fR, or \fB.S\fR.  Some other common extensions for \*(C+ and
+assembly are also recognized.  If cpp does not recognize the extension,
+it will treat the file as C; this is the most generic mode.
+.Sp
+\&\fINote:\fR Previous versions of cpp accepted a \fB\-lang\fR option
+which selected both the language and the standards conformance level.
+This option has been removed, because it conflicts with the \fB\-l\fR
+option.
+.IP "\fB\-std=\fR\fIstandard\fR" 4
+.IX Item "-std=standard"
+.PD 0
+.IP "\fB\-ansi\fR" 4
+.IX Item "-ansi"
+.PD
+Specify the standard to which the code should conform.  Currently \s-1CPP\s0
+knows about C and \*(C+ standards; others may be added in the future.
+.Sp
+\&\fIstandard\fR
+may be one of:
+.RS 4
+.ie n .IP """iso9899:1990""" 4
+.el .IP "\f(CWiso9899:1990\fR" 4
+.IX Item "iso9899:1990"
+.PD 0
+.ie n .IP """c89""" 4
+.el .IP "\f(CWc89\fR" 4
+.IX Item "c89"
+.PD
+The \s-1ISO\s0 C standard from 1990.  \fBc89\fR is the customary shorthand for
+this version of the standard.
+.Sp
+The \fB\-ansi\fR option is equivalent to \fB\-std=c89\fR.
+.ie n .IP """iso9899:199409""" 4
+.el .IP "\f(CWiso9899:199409\fR" 4
+.IX Item "iso9899:199409"
+The 1990 C standard, as amended in 1994.
+.ie n .IP """iso9899:1999""" 4
+.el .IP "\f(CWiso9899:1999\fR" 4
+.IX Item "iso9899:1999"
+.PD 0
+.ie n .IP """c99""" 4
+.el .IP "\f(CWc99\fR" 4
+.IX Item "c99"
+.ie n .IP """iso9899:199x""" 4
+.el .IP "\f(CWiso9899:199x\fR" 4
+.IX Item "iso9899:199x"
+.ie n .IP """c9x""" 4
+.el .IP "\f(CWc9x\fR" 4
+.IX Item "c9x"
+.PD
+The revised \s-1ISO\s0 C standard, published in December 1999.  Before
+publication, this was known as C9X.
+.ie n .IP """gnu89""" 4
+.el .IP "\f(CWgnu89\fR" 4
+.IX Item "gnu89"
+The 1990 C standard plus \s-1GNU\s0 extensions.  This is the default.
+.ie n .IP """gnu99""" 4
+.el .IP "\f(CWgnu99\fR" 4
+.IX Item "gnu99"
+.PD 0
+.ie n .IP """gnu9x""" 4
+.el .IP "\f(CWgnu9x\fR" 4
+.IX Item "gnu9x"
+.PD
+The 1999 C standard plus \s-1GNU\s0 extensions.
+.ie n .IP """c++98""" 4
+.el .IP "\f(CWc++98\fR" 4
+.IX Item "c++98"
+The 1998 \s-1ISO\s0 \*(C+ standard plus amendments.
+.ie n .IP """gnu++98""" 4
+.el .IP "\f(CWgnu++98\fR" 4
+.IX Item "gnu++98"
+The same as \fB\-std=c++98\fR plus \s-1GNU\s0 extensions.  This is the
+default for \*(C+ code.
+.RE
+.RS 4
+.RE
+.IP "\fB\-I\-\fR" 4
+.IX Item "-I-"
+Split the include path.  Any directories specified with \fB\-I\fR
+options before \fB\-I\-\fR are searched only for headers requested with
+\&\f(CW\*(C`#include\ "\f(CIfile\f(CW"\*(C'\fR; they are not searched for
+\&\f(CW\*(C`#include\ <\f(CIfile\f(CW>\*(C'\fR.  If additional directories are
+specified with \fB\-I\fR options after the \fB\-I\-\fR, those
+directories are searched for all \fB#include\fR directives.
+.Sp
+In addition, \fB\-I\-\fR inhibits the use of the directory of the current
+file directory as the first search directory for \f(CW\*(C`#include\ "\f(CIfile\f(CW"\*(C'\fR.
+.Sp
+This option has been deprecated.
+.IP "\fB\-nostdinc\fR" 4
+.IX Item "-nostdinc"
+Do not search the standard system directories for header files.
+Only the directories you have specified with \fB\-I\fR options
+(and the directory of the current file, if appropriate) are searched.
+.IP "\fB\-nostdinc++\fR" 4
+.IX Item "-nostdinc++"
+Do not search for header files in the \*(C+\-specific standard directories,
+but do still search the other standard directories.  (This option is
+used when building the \*(C+ library.)
+.IP "\fB\-include\fR \fIfile\fR" 4
+.IX Item "-include file"
+Process \fIfile\fR as if \f(CW\*(C`#include "file"\*(C'\fR appeared as the first
+line of the primary source file.  However, the first directory searched
+for \fIfile\fR is the preprocessor's working directory \fIinstead of\fR
+the directory containing the main source file.  If not found there, it
+is searched for in the remainder of the \f(CW\*(C`#include "..."\*(C'\fR search
+chain as normal.
+.Sp
+If multiple \fB\-include\fR options are given, the files are included
+in the order they appear on the command line.
+.IP "\fB\-imacros\fR \fIfile\fR" 4
+.IX Item "-imacros file"
+Exactly like \fB\-include\fR, except that any output produced by
+scanning \fIfile\fR is thrown away.  Macros it defines remain defined.
+This allows you to acquire all the macros from a header without also
+processing its declarations.
+.Sp
+All files specified by \fB\-imacros\fR are processed before all files
+specified by \fB\-include\fR.
+.IP "\fB\-idirafter\fR \fIdir\fR" 4
+.IX Item "-idirafter dir"
+Search \fIdir\fR for header files, but do it \fIafter\fR all
+directories specified with \fB\-I\fR and the standard system directories
+have been exhausted.  \fIdir\fR is treated as a system include directory.
+.IP "\fB\-iprefix\fR \fIprefix\fR" 4
+.IX Item "-iprefix prefix"
+Specify \fIprefix\fR as the prefix for subsequent \fB\-iwithprefix\fR
+options.  If the prefix represents a directory, you should include the
+final \fB/\fR.
+.IP "\fB\-iwithprefix\fR \fIdir\fR" 4
+.IX Item "-iwithprefix dir"
+.PD 0
+.IP "\fB\-iwithprefixbefore\fR \fIdir\fR" 4
+.IX Item "-iwithprefixbefore dir"
+.PD
+Append \fIdir\fR to the prefix specified previously with
+\&\fB\-iprefix\fR, and add the resulting directory to the include search
+path.  \fB\-iwithprefixbefore\fR puts it in the same place \fB\-I\fR
+would; \fB\-iwithprefix\fR puts it where \fB\-idirafter\fR would.
+.IP "\fB\-isysroot\fR \fIdir\fR" 4
+.IX Item "-isysroot dir"
+This option is like the \fB\-\-sysroot\fR option, but applies only to
+header files.  See the \fB\-\-sysroot\fR option for more information.
+.IP "\fB\-imultilib\fR \fIdir\fR" 4
+.IX Item "-imultilib dir"
+Use \fIdir\fR as a subdirectory of the directory containing
+target-specific \*(C+ headers.
+.IP "\fB\-isystem\fR \fIdir\fR" 4
+.IX Item "-isystem dir"
+Search \fIdir\fR for header files, after all directories specified by
+\&\fB\-I\fR but before the standard system directories.  Mark it
+as a system directory, so that it gets the same special treatment as
+is applied to the standard system directories.
+.IP "\fB\-iquote\fR \fIdir\fR" 4
+.IX Item "-iquote dir"
+Search \fIdir\fR only for header files requested with
+\&\f(CW\*(C`#include\ "\f(CIfile\f(CW"\*(C'\fR; they are not searched for
+\&\f(CW\*(C`#include\ <\f(CIfile\f(CW>\*(C'\fR, before all directories specified by
+\&\fB\-I\fR and before the standard system directories.
+.IP "\fB\-fdollars\-in\-identifiers\fR" 4
+.IX Item "-fdollars-in-identifiers"
+Accept \fB$\fR in identifiers.
+.IP "\fB\-fextended\-identifiers\fR" 4
+.IX Item "-fextended-identifiers"
+Accept universal character names in identifiers.  This option is
+experimental; in a future version of \s-1GCC\s0, it will be enabled by
+default for C99 and \*(C+.
+.IP "\fB\-fpreprocessed\fR" 4
+.IX Item "-fpreprocessed"
+Indicate to the preprocessor that the input file has already been
+preprocessed.  This suppresses things like macro expansion, trigraph
+conversion, escaped newline splicing, and processing of most directives.
+The preprocessor still recognizes and removes comments, so that you can
+pass a file preprocessed with \fB\-C\fR to the compiler without
+problems.  In this mode the integrated preprocessor is little more than
+a tokenizer for the front ends.
+.Sp
+\&\fB\-fpreprocessed\fR is implicit if the input file has one of the
+extensions \fB.i\fR, \fB.ii\fR or \fB.mi\fR.  These are the
+extensions that \s-1GCC\s0 uses for preprocessed files created by
+\&\fB\-save\-temps\fR.
+.IP "\fB\-ftabstop=\fR\fIwidth\fR" 4
+.IX Item "-ftabstop=width"
+Set the distance between tab stops.  This helps the preprocessor report
+correct column numbers in warnings or errors, even if tabs appear on the
+line.  If the value is less than 1 or greater than 100, the option is
+ignored.  The default is 8.
+.IP "\fB\-fexec\-charset=\fR\fIcharset\fR" 4
+.IX Item "-fexec-charset=charset"
+Set the execution character set, used for string and character
+constants.  The default is \s-1UTF\-8\s0.  \fIcharset\fR can be any encoding
+supported by the system's \f(CW\*(C`iconv\*(C'\fR library routine.
+.IP "\fB\-fwide\-exec\-charset=\fR\fIcharset\fR" 4
+.IX Item "-fwide-exec-charset=charset"
+Set the wide execution character set, used for wide string and
+character constants.  The default is \s-1UTF\-32\s0 or \s-1UTF\-16\s0, whichever
+corresponds to the width of \f(CW\*(C`wchar_t\*(C'\fR.  As with
+\&\fB\-fexec\-charset\fR, \fIcharset\fR can be any encoding supported
+by the system's \f(CW\*(C`iconv\*(C'\fR library routine; however, you will have
+problems with encodings that do not fit exactly in \f(CW\*(C`wchar_t\*(C'\fR.
+.IP "\fB\-finput\-charset=\fR\fIcharset\fR" 4
+.IX Item "-finput-charset=charset"
+Set the input character set, used for translation from the character
+set of the input file to the source character set used by \s-1GCC\s0.  If the
+locale does not specify, or \s-1GCC\s0 cannot get this information from the
+locale, the default is \s-1UTF\-8\s0.  This can be overridden by either the locale
+or this command line option.  Currently the command line option takes
+precedence if there's a conflict.  \fIcharset\fR can be any encoding
+supported by the system's \f(CW\*(C`iconv\*(C'\fR library routine.
+.IP "\fB\-fworking\-directory\fR" 4
+.IX Item "-fworking-directory"
+Enable generation of linemarkers in the preprocessor output that will
+let the compiler know the current working directory at the time of
+preprocessing.  When this option is enabled, the preprocessor will
+emit, after the initial linemarker, a second linemarker with the
+current working directory followed by two slashes.  \s-1GCC\s0 will use this
+directory, when it's present in the preprocessed input, as the
+directory emitted as the current working directory in some debugging
+information formats.  This option is implicitly enabled if debugging
+information is enabled, but this can be inhibited with the negated
+form \fB\-fno\-working\-directory\fR.  If the \fB\-P\fR flag is
+present in the command line, this option has no effect, since no
+\&\f(CW\*(C`#line\*(C'\fR directives are emitted whatsoever.
+.IP "\fB\-fno\-show\-column\fR" 4
+.IX Item "-fno-show-column"
+Do not print column numbers in diagnostics.  This may be necessary if
+diagnostics are being scanned by a program that does not understand the
+column numbers, such as \fBdejagnu\fR.
+.IP "\fB\-A\fR \fIpredicate\fR\fB=\fR\fIanswer\fR" 4
+.IX Item "-A predicate=answer"
+Make an assertion with the predicate \fIpredicate\fR and answer
+\&\fIanswer\fR.  This form is preferred to the older form \fB\-A\fR
+\&\fIpredicate\fR\fB(\fR\fIanswer\fR\fB)\fR, which is still supported, because
+it does not use shell special characters.
+.IP "\fB\-A \-\fR\fIpredicate\fR\fB=\fR\fIanswer\fR" 4
+.IX Item "-A -predicate=answer"
+Cancel an assertion with the predicate \fIpredicate\fR and answer
+\&\fIanswer\fR.
+.IP "\fB\-dCHARS\fR" 4
+.IX Item "-dCHARS"
+\&\fI\s-1CHARS\s0\fR is a sequence of one or more of the following characters,
+and must not be preceded by a space.  Other characters are interpreted
+by the compiler proper, or reserved for future versions of \s-1GCC\s0, and so
+are silently ignored.  If you specify characters whose behavior
+conflicts, the result is undefined.
+.RS 4
+.IP "\fBM\fR" 4
+.IX Item "M"
+Instead of the normal output, generate a list of \fB#define\fR
+directives for all the macros defined during the execution of the
+preprocessor, including predefined macros.  This gives you a way of
+finding out what is predefined in your version of the preprocessor.
+Assuming you have no file \fIfoo.h\fR, the command
+.Sp
+.Vb 1
+\&        touch foo.h; cpp -dM foo.h
+.Ve
+.Sp
+will show all the predefined macros.
+.IP "\fBD\fR" 4
+.IX Item "D"
+Like \fBM\fR except in two respects: it does \fInot\fR include the
+predefined macros, and it outputs \fIboth\fR the \fB#define\fR
+directives and the result of preprocessing.  Both kinds of output go to
+the standard output file.
+.IP "\fBN\fR" 4
+.IX Item "N"
+Like \fBD\fR, but emit only the macro names, not their expansions.
+.IP "\fBI\fR" 4
+.IX Item "I"
+Output \fB#include\fR directives in addition to the result of
+preprocessing.
+.RE
+.RS 4
+.RE
+.IP "\fB\-P\fR" 4
+.IX Item "-P"
+Inhibit generation of linemarkers in the output from the preprocessor.
+This might be useful when running the preprocessor on something that is
+not C code, and will be sent to a program which might be confused by the
+linemarkers.
+.IP "\fB\-C\fR" 4
+.IX Item "-C"
+Do not discard comments.  All comments are passed through to the output
+file, except for comments in processed directives, which are deleted
+along with the directive.
+.Sp
+You should be prepared for side effects when using \fB\-C\fR; it
+causes the preprocessor to treat comments as tokens in their own right.
+For example, comments appearing at the start of what would be a
+directive line have the effect of turning that line into an ordinary
+source line, since the first token on the line is no longer a \fB#\fR.
+.IP "\fB\-CC\fR" 4
+.IX Item "-CC"
+Do not discard comments, including during macro expansion.  This is
+like \fB\-C\fR, except that comments contained within macros are
+also passed through to the output file where the macro is expanded.
+.Sp
+In addition to the side-effects of the \fB\-C\fR option, the
+\&\fB\-CC\fR option causes all \*(C+\-style comments inside a macro
+to be converted to C\-style comments.  This is to prevent later use
+of that macro from inadvertently commenting out the remainder of
+the source line.
+.Sp
+The \fB\-CC\fR option is generally used to support lint comments.
+.IP "\fB\-traditional\-cpp\fR" 4
+.IX Item "-traditional-cpp"
+Try to imitate the behavior of old-fashioned C preprocessors, as
+opposed to \s-1ISO\s0 C preprocessors.
+.IP "\fB\-trigraphs\fR" 4
+.IX Item "-trigraphs"
+Process trigraph sequences.
+.IP "\fB\-remap\fR" 4
+.IX Item "-remap"
+Enable special code to work around file systems which only permit very
+short file names, such as \s-1MS\-DOS\s0.
+.IP "\fB\-\-help\fR" 4
+.IX Item "--help"
+.PD 0
+.IP "\fB\-\-target\-help\fR" 4
+.IX Item "--target-help"
+.PD
+Print text describing all the command line options instead of
+preprocessing anything.
+.IP "\fB\-v\fR" 4
+.IX Item "-v"
+Verbose mode.  Print out \s-1GNU\s0 \s-1CPP\s0's version number at the beginning of
+execution, and report the final form of the include path.
+.IP "\fB\-H\fR" 4
+.IX Item "-H"
+Print the name of each header file used, in addition to other normal
+activities.  Each name is indented to show how deep in the
+\&\fB#include\fR stack it is.  Precompiled header files are also
+printed, even if they are found to be invalid; an invalid precompiled
+header file is printed with \fB...x\fR and a valid one with \fB...!\fR .
+.IP "\fB\-version\fR" 4
+.IX Item "-version"
+.PD 0
+.IP "\fB\-\-version\fR" 4
+.IX Item "--version"
+.PD
+Print out \s-1GNU\s0 \s-1CPP\s0's version number.  With one dash, proceed to
+preprocess as normal.  With two dashes, exit immediately.
+.SH "ENVIRONMENT"
+.IX Header "ENVIRONMENT"
+This section describes the environment variables that affect how \s-1CPP\s0
+operates.  You can use them to specify directories or prefixes to use
+when searching for include files, or to control dependency output.
+.PP
+Note that you can also specify places to search using options such as
+\&\fB\-I\fR, and control dependency output with options like
+\&\fB\-M\fR.  These take precedence over
+environment variables, which in turn take precedence over the
+configuration of \s-1GCC\s0.
+.IP "\fB\s-1CPATH\s0\fR" 4
+.IX Item "CPATH"
+.PD 0
+.IP "\fBC_INCLUDE_PATH\fR" 4
+.IX Item "C_INCLUDE_PATH"
+.IP "\fB\s-1CPLUS_INCLUDE_PATH\s0\fR" 4
+.IX Item "CPLUS_INCLUDE_PATH"
+.PD
+Each variable's value is a list of directories separated by a special
+character, much like \fB\s-1PATH\s0\fR, in which to look for header files.
+The special character, \f(CW\*(C`PATH_SEPARATOR\*(C'\fR, is target-dependent and
+determined at \s-1GCC\s0 build time.  For Microsoft Windows-based targets it is a
+semicolon, and for almost all other targets it is a colon.
+.Sp
+\&\fB\s-1CPATH\s0\fR specifies a list of directories to be searched as if
+specified with \fB\-I\fR, but after any paths given with \fB\-I\fR
+options on the command line.  This environment variable is used
+regardless of which language is being preprocessed.
+.Sp
+The remaining environment variables apply only when preprocessing the
+particular language indicated.  Each specifies a list of directories
+to be searched as if specified with \fB\-isystem\fR, but after any
+paths given with \fB\-isystem\fR options on the command line.
+.Sp
+In all these variables, an empty element instructs the compiler to
+search its current working directory.  Empty elements can appear at the
+beginning or end of a path.  For instance, if the value of
+\&\fB\s-1CPATH\s0\fR is \f(CW\*(C`:/special/include\*(C'\fR, that has the same
+effect as \fB\-I.\ \-I/special/include\fR.
+.IP "\fB\s-1DEPENDENCIES_OUTPUT\s0\fR" 4
+.IX Item "DEPENDENCIES_OUTPUT"
+If this variable is set, its value specifies how to output
+dependencies for Make based on the non-system header files processed
+by the compiler.  System header files are ignored in the dependency
+output.
+.Sp
+The value of \fB\s-1DEPENDENCIES_OUTPUT\s0\fR can be just a file name, in
+which case the Make rules are written to that file, guessing the target
+name from the source file name.  Or the value can have the form
+\&\fIfile\fR\fB \fR\fItarget\fR, in which case the rules are written to
+file \fIfile\fR using \fItarget\fR as the target name.
+.Sp

*** DIFF OUTPUT TRUNCATED AT 1000 LINES ***


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