.\" Automatically generated by Pod::Man v1.34, Pod::Parser v1.13 .\" .\" 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++. 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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 "GCC 1" .TH GCC 1 "2004-11-05" "gcc-3.4.3" "GNU" .SH "NAME" gcc \- GNU project C and C++ compiler .SH "SYNOPSIS" .IX Header "SYNOPSIS" gcc [\fB\-c\fR|\fB\-S\fR|\fB\-E\fR] [\fB\-std=\fR\fIstandard\fR] [\fB\-g\fR] [\fB\-pg\fR] [\fB\-O\fR\fIlevel\fR] [\fB\-W\fR\fIwarn\fR...] [\fB\-pedantic\fR] [\fB\-I\fR\fIdir\fR...] [\fB\-L\fR\fIdir\fR...] [\fB\-D\fR\fImacro\fR[=\fIdefn\fR]...] [\fB\-U\fR\fImacro\fR] [\fB\-f\fR\fIoption\fR...] [\fB\-m\fR\fImachine-option\fR...] [\fB\-o\fR \fIoutfile\fR] \fIinfile\fR... .PP Only the most useful options are listed here; see below for the remainder. \fBg++\fR accepts mostly the same options as \fBgcc\fR. .SH "DESCRIPTION" .IX Header "DESCRIPTION" When you invoke \s-1GCC\s0, it normally does preprocessing, compilation, assembly and linking. The ``overall options'' allow you to stop this process at an intermediate stage. For example, the \fB\-c\fR option says not to run the linker. Then the output consists of object files output by the assembler. .PP Other options are passed on to one stage of processing. Some options control the preprocessor and others the compiler itself. Yet other options control the assembler and linker; most of these are not documented here, since you rarely need to use any of them. .PP Most of the command line options that you can use with \s-1GCC\s0 are useful for C programs; when an option is only useful with another language (usually \*(C+), the explanation says so explicitly. If the description for a particular option does not mention a source language, you can use that option with all supported languages. .PP The \fBgcc\fR program accepts options and file names as operands. Many options have multi-letter names; therefore multiple single-letter options may \fInot\fR be grouped: \fB\-dr\fR is very different from \fB\-d\ \-r\fR. .PP You can mix options and other arguments. For the most part, the order you use doesn't matter. Order does matter when you use several options of the same kind; for example, if you specify \fB\-L\fR more than once, the directories are searched in the order specified. .PP Many options have long names starting with \fB\-f\fR or with \&\fB\-W\fR\-\-\-for example, \fB\-fforce\-mem\fR, \&\fB\-fstrength\-reduce\fR, \fB\-Wformat\fR and so on. Most of these have both positive and negative forms; the negative form of \&\fB\-ffoo\fR would be \fB\-fno\-foo\fR. This manual documents only one of these two forms, whichever one is not the default. .SH "OPTIONS" .IX Header "OPTIONS" .Sh "Option Summary" .IX Subsection "Option Summary" Here is a summary of all the options, grouped by type. Explanations are in the following sections. .IP "\fIOverall Options\fR" 4 .IX Item "Overall Options" \&\fB\-c \-S \-E \-o\fR \fIfile\fR \fB\-pipe \-pass\-exit\-codes \&\-x\fR \fIlanguage\fR \fB\-v \-### \-\-help \-\-target\-help \-\-version\fR .IP "\fIC Language Options\fR" 4 .IX Item "C Language Options" \&\fB\-ansi \-std=\fR\fIstandard\fR \fB\-aux\-info\fR \fIfilename\fR \&\fB\-fno\-asm \-fno\-builtin \-fno\-builtin\-\fR\fIfunction\fR \&\fB\-fhosted \-ffreestanding \-fms\-extensions \&\-trigraphs \-no\-integrated\-cpp \-traditional \-traditional\-cpp \&\-fallow\-single\-precision \-fcond\-mismatch \&\-fsigned\-bitfields \-fsigned\-char \&\-funsigned\-bitfields \-funsigned\-char \&\-fwritable\-strings\fR .IP "\fI\*(C+ Language Options\fR" 4 .IX Item " Language Options" \&\fB\-fabi\-version=\fR\fIn\fR \fB\-fno\-access\-control \-fcheck\-new \&\-fconserve\-space \-fno\-const\-strings \&\-fno\-elide\-constructors \&\-fno\-enforce\-eh\-specs \&\-ffor\-scope \-fno\-for\-scope \-fno\-gnu\-keywords \&\-fno\-implicit\-templates \&\-fno\-implicit\-inline\-templates \&\-fno\-implement\-inlines \-fms\-extensions \&\-fno\-nonansi\-builtins \-fno\-operator\-names \&\-fno\-optional\-diags \-fpermissive \&\-frepo \-fno\-rtti \-fstats \-ftemplate\-depth\-\fR\fIn\fR \&\fB\-fuse\-cxa\-atexit \-fno\-weak \-nostdinc++ \&\-fno\-default\-inline \-Wabi \-Wctor\-dtor\-privacy \&\-Wnon\-virtual\-dtor \-Wreorder \&\-Weffc++ \-Wno\-deprecated \&\-Wno\-non\-template\-friend \-Wold\-style\-cast \&\-Woverloaded\-virtual \-Wno\-pmf\-conversions \&\-Wsign\-promo \-Wsynth\fR .IP "\fIObjective-C Language Options\fR" 4 .IX Item "Objective-C Language Options" \&\fB\-fconstant\-string\-class=\fR\fIclass-name\fR \&\fB\-fgnu\-runtime \-fnext\-runtime \&\-fno\-nil\-receivers \&\-fobjc\-exceptions \&\-freplace\-objc\-classes \&\-fzero\-link \&\-gen\-decls \&\-Wno\-protocol \-Wselector \-Wundeclared\-selector\fR .IP "\fILanguage Independent Options\fR" 4 .IX Item "Language Independent Options" \&\fB\-fmessage\-length=\fR\fIn\fR \&\fB\-fdiagnostics\-show\-location=\fR[\fBonce\fR|\fBevery-line\fR] .IP "\fIWarning Options\fR" 4 .IX Item "Warning Options" \&\fB\-fsyntax\-only \-pedantic \-pedantic\-errors \&\-w \-Wextra \-Wall \-Waggregate\-return \&\-Wcast\-align \-Wcast\-qual \-Wchar\-subscripts \-Wcomment \&\-Wconversion \-Wno\-deprecated\-declarations \&\-Wdisabled\-optimization \-Wno\-div\-by\-zero \-Wendif\-labels \&\-Werror \-Werror\-implicit\-function\-declaration \&\-Wfloat\-equal \-Wformat \-Wformat=2 \&\-Wno\-format\-extra\-args \-Wformat\-nonliteral \&\-Wformat\-security \-Wformat\-y2k \&\-Wimplicit \-Wimplicit\-function\-declaration \-Wimplicit\-int \&\-Wimport \-Wno\-import \-Winit\-self \-Winline \&\-Wno\-invalid\-offsetof \-Winvalid\-pch \&\-Wlarger\-than\-\fR\fIlen\fR \fB\-Wlong\-long \&\-Wmain \-Wmissing\-braces \&\-Wmissing\-format\-attribute \-Wmissing\-noreturn \&\-Wno\-multichar \-Wnonnull \-Wpacked \-Wpadded \&\-Wparentheses \-Wpointer\-arith \-Wredundant\-decls \&\-Wreturn\-type \-Wsequence\-point \-Wshadow \&\-Wsign\-compare \-Wstrict\-aliasing \&\-Wswitch \-Wswitch\-default \-Wswitch\-enum \&\-Wsystem\-headers \-Wtrigraphs \-Wundef \-Wuninitialized \&\-Wunknown\-pragmas \-Wunreachable\-code \&\-Wunused \-Wunused\-function \-Wunused\-label \-Wunused\-parameter \&\-Wunused\-value \-Wunused\-variable \-Wwrite\-strings\fR .IP "\fIC\-only Warning Options\fR" 4 .IX Item "C-only Warning Options" \&\fB\-Wbad\-function\-cast \-Wmissing\-declarations \&\-Wmissing\-prototypes \-Wnested\-externs \-Wold\-style\-definition \&\-Wstrict\-prototypes \-Wtraditional \&\-Wdeclaration\-after\-statement\fR .IP "\fIDebugging Options\fR" 4 .IX Item "Debugging Options" \&\fB\-d\fR\fIletters\fR \fB\-dumpspecs \-dumpmachine \-dumpversion \&\-fdump\-unnumbered \-fdump\-translation\-unit\fR[\fB\-\fR\fIn\fR] \&\fB\-fdump\-class\-hierarchy\fR[\fB\-\fR\fIn\fR] \&\fB\-fdump\-tree\-original\fR[\fB\-\fR\fIn\fR] \&\fB\-fdump\-tree\-optimized\fR[\fB\-\fR\fIn\fR] \&\fB\-fdump\-tree\-inlined\fR[\fB\-\fR\fIn\fR] \&\fB\-feliminate\-dwarf2\-dups \-feliminate\-unused\-debug\-types \&\-feliminate\-unused\-debug\-symbols \-fmem\-report \-fprofile\-arcs \&\-frandom\-seed=\fR\fIstring\fR \fB\-fsched\-verbose=\fR\fIn\fR \&\fB\-ftest\-coverage \-ftime\-report \&\-g \-g\fR\fIlevel\fR \fB\-gcoff \-gdwarf\-2 \&\-ggdb \-gstabs \-gstabs+ \-gvms \-gxcoff \-gxcoff+ \&\-p \-pg \-print\-file\-name=\fR\fIlibrary\fR \fB\-print\-libgcc\-file\-name \&\-print\-multi\-directory \-print\-multi\-lib \&\-print\-prog\-name=\fR\fIprogram\fR \fB\-print\-search\-dirs \-Q \&\-save\-temps \-time\fR .IP "\fIOptimization Options\fR" 4 .IX Item "Optimization Options" \&\fB\-falign\-functions=\fR\fIn\fR \fB\-falign\-jumps=\fR\fIn\fR \&\fB\-falign\-labels=\fR\fIn\fR \fB\-falign\-loops=\fR\fIn\fR \&\fB\-fbranch\-probabilities \-fprofile\-values \-fvpt \-fbranch\-target\-load\-optimize \&\-fbranch\-target\-load\-optimize2 \-fcaller\-saves \-fcprop\-registers \&\-fcse\-follow\-jumps \-fcse\-skip\-blocks \-fdata\-sections \&\-fdelayed\-branch \-fdelete\-null\-pointer\-checks \&\-fexpensive\-optimizations \-ffast\-math \-ffloat\-store \&\-fforce\-addr \-fforce\-mem \-ffunction\-sections \&\-fgcse \-fgcse\-lm \-fgcse\-sm \-fgcse\-las \-floop\-optimize \&\-fcrossjumping \-fif\-conversion \-fif\-conversion2 \&\-finline\-functions \-finline\-limit=\fR\fIn\fR \fB\-fkeep\-inline\-functions \&\-fkeep\-static\-consts \-fmerge\-constants \-fmerge\-all\-constants \&\-fmove\-all\-movables \-fnew\-ra \-fno\-branch\-count\-reg \&\-fno\-default\-inline \-fno\-defer\-pop \&\-fno\-function\-cse \-fno\-guess\-branch\-probability \&\-fno\-inline \-fno\-math\-errno \-fno\-peephole \-fno\-peephole2 \&\-funsafe\-math\-optimizations \-ffinite\-math\-only \&\-fno\-trapping\-math \-fno\-zero\-initialized\-in\-bss \&\-fomit\-frame\-pointer \-foptimize\-register\-move \&\-foptimize\-sibling\-calls \-fprefetch\-loop\-arrays \&\-fprofile\-generate \-fprofile\-use \&\-freduce\-all\-givs \-fregmove \-frename\-registers \&\-freorder\-blocks \-freorder\-functions \&\-frerun\-cse\-after\-loop \-frerun\-loop\-opt \&\-frounding\-math \-fschedule\-insns \-fschedule\-insns2 \&\-fno\-sched\-interblock \-fno\-sched\-spec \-fsched\-spec\-load \&\-fsched\-spec\-load\-dangerous \&\-fsched\-stalled\-insns=\fR\fIn\fR \fB\-sched\-stalled\-insns\-dep=\fR\fIn\fR \&\fB\-fsched2\-use\-superblocks \&\-fsched2\-use\-traces \-fsignaling\-nans \&\-fsingle\-precision\-constant \&\-fstrength\-reduce \-fstrict\-aliasing \-ftracer \-fthread\-jumps \&\-funroll\-all\-loops \-funroll\-loops \-fpeel\-loops \&\-funswitch\-loops \-fold\-unroll\-loops \-fold\-unroll\-all\-loops \&\-\-param\fR \fIname\fR\fB=\fR\fIvalue\fR \&\fB\-O \-O0 \-O1 \-O2 \-O3 \-Os\fR .IP "\fIPreprocessor Options\fR" 4 .IX Item "Preprocessor Options" \&\fB\-A\fR\fIquestion\fR\fB=\fR\fIanswer\fR \&\fB\-A\-\fR\fIquestion\fR[\fB=\fR\fIanswer\fR] \&\fB\-C \-dD \-dI \-dM \-dN \&\-D\fR\fImacro\fR[\fB=\fR\fIdefn\fR] \fB\-E \-H \&\-idirafter\fR \fIdir\fR \&\fB\-include\fR \fIfile\fR \fB\-imacros\fR \fIfile\fR \&\fB\-iprefix\fR \fIfile\fR \fB\-iwithprefix\fR \fIdir\fR \&\fB\-iwithprefixbefore\fR \fIdir\fR \fB\-isystem\fR \fIdir\fR \&\fB\-M \-MM \-MF \-MG \-MP \-MQ \-MT \-nostdinc \&\-P \-fworking\-directory \-remap \&\-trigraphs \-undef \-U\fR\fImacro\fR \fB\-Wp,\fR\fIoption\fR \&\fB\-Xpreprocessor\fR \fIoption\fR .IP "\fIAssembler Option\fR" 4 .IX Item "Assembler Option" \&\fB\-Wa,\fR\fIoption\fR \fB\-Xassembler\fR \fIoption\fR .IP "\fILinker Options\fR" 4 .IX Item "Linker Options" \&\fIobject-file-name\fR \fB\-l\fR\fIlibrary\fR \&\fB\-nostartfiles \-nodefaultlibs \-nostdlib \-pie \&\-s \-static \-static\-libgcc \-shared \-shared\-libgcc \-symbolic \&\-Wl,\fR\fIoption\fR \fB\-Xlinker\fR \fIoption\fR \&\fB\-u\fR \fIsymbol\fR .IP "\fIDirectory Options\fR" 4 .IX Item "Directory Options" \&\fB\-B\fR\fIprefix\fR \fB\-I\fR\fIdir\fR \fB\-I\- \-L\fR\fIdir\fR \fB\-specs=\fR\fIfile\fR .IP "\fITarget Options\fR" 4 .IX Item "Target Options" \&\fB\-V\fR \fIversion\fR \fB\-b\fR \fImachine\fR .IP "\fIMachine Dependent Options\fR" 4 .IX Item "Machine Dependent Options" \&\fIM680x0 Options\fR \&\fB\-m68000 \-m68020 \-m68020\-40 \-m68020\-60 \-m68030 \-m68040 \&\-m68060 \-mcpu32 \-m5200 \-m68881 \-mbitfield \-mc68000 \-mc68020 \&\-mnobitfield \-mrtd \-mshort \-msoft\-float \-mpcrel \&\-malign\-int \-mstrict\-align \-msep\-data \-mno\-sep\-data \&\-mshared\-library\-id=n \-mid\-shared\-library \-mno\-id\-shared\-library\fR .Sp \&\fIM68hc1x Options\fR \&\fB\-m6811 \-m6812 \-m68hc11 \-m68hc12 \-m68hcs12 \&\-mauto\-incdec \-minmax \-mlong\-calls \-mshort \&\-msoft\-reg\-count=\fR\fIcount\fR .Sp \&\fI\s-1VAX\s0 Options\fR \&\fB\-mg \-mgnu \-munix\fR .Sp \&\fI\s-1SPARC\s0 Options\fR \&\fB\-mcpu=\fR\fIcpu-type\fR \&\fB\-mtune=\fR\fIcpu-type\fR \&\fB\-mcmodel=\fR\fIcode-model\fR \&\fB\-m32 \-m64 \-mapp\-regs \-mno\-app\-regs \&\-mfaster\-structs \-mno\-faster\-structs \&\-mflat \-mno\-flat \-mfpu \-mno\-fpu \&\-mhard\-float \-msoft\-float \&\-mhard\-quad\-float \-msoft\-quad\-float \&\-mimpure\-text \-mno\-impure\-text \-mlittle\-endian \&\-mstack\-bias \-mno\-stack\-bias \&\-munaligned\-doubles \-mno\-unaligned\-doubles \&\-mv8plus \-mno\-v8plus \-mvis \-mno\-vis \&\-mcypress \-mf930 \-mf934 \&\-msparclite \-msupersparc \-mv8 \&\-threads \-pthreads\fR .Sp \&\fI\s-1ARM\s0 Options\fR \&\fB\-mapcs\-frame \-mno\-apcs\-frame \&\-mapcs\-26 \-mapcs\-32 \&\-mapcs\-stack\-check \-mno\-apcs\-stack\-check \&\-mapcs\-float \-mno\-apcs\-float \&\-mapcs\-reentrant \-mno\-apcs\-reentrant \&\-msched\-prolog \-mno\-sched\-prolog \&\-mlittle\-endian \-mbig\-endian \-mwords\-little\-endian \&\-malignment\-traps \-mno\-alignment\-traps \&\-msoft\-float \-mhard\-float \-mfpe \&\-mthumb\-interwork \-mno\-thumb\-interwork \&\-mcpu=\fR\fIname\fR \fB\-march=\fR\fIname\fR \fB\-mfpe=\fR\fIname\fR \&\fB\-mstructure\-size\-boundary=\fR\fIn\fR \&\fB\-mabort\-on\-noreturn \&\-mlong\-calls \-mno\-long\-calls \&\-msingle\-pic\-base \-mno\-single\-pic\-base \&\-mpic\-register=\fR\fIreg\fR \&\fB\-mnop\-fun\-dllimport \&\-mcirrus\-fix\-invalid\-insns \-mno\-cirrus\-fix\-invalid\-insns \&\-mpoke\-function\-name \&\-mthumb \-marm \&\-mtpcs\-frame \-mtpcs\-leaf\-frame \&\-mcaller\-super\-interworking \-mcallee\-super\-interworking\fR .Sp \&\fI\s-1MN10300\s0 Options\fR \&\fB\-mmult\-bug \-mno\-mult\-bug \&\-mam33 \-mno\-am33 \&\-mam33\-2 \-mno\-am33\-2 \&\-mno\-crt0 \-mrelax\fR .Sp \&\fIM32R/D Options\fR \&\fB\-m32r2 \-m32rx \-m32r \&\-mdebug \&\-malign\-loops \-mno\-align\-loops \&\-missue\-rate=\fR\fInumber\fR \&\fB\-mbranch\-cost=\fR\fInumber\fR \&\fB\-mmodel=\fR\fIcode-size-model-type\fR \&\fB\-msdata=\fR\fIsdata-type\fR \&\fB\-mno\-flush\-func \-mflush\-func=\fR\fIname\fR \&\fB\-mno\-flush\-trap \-mflush\-trap=\fR\fInumber\fR \&\fB\-G\fR \fInum\fR .Sp \&\fI\s-1RS/6000\s0 and PowerPC Options\fR \&\fB\-mcpu=\fR\fIcpu-type\fR \&\fB\-mtune=\fR\fIcpu-type\fR \&\fB\-mpower \-mno\-power \-mpower2 \-mno\-power2 \&\-mpowerpc \-mpowerpc64 \-mno\-powerpc \&\-maltivec \-mno\-altivec \&\-mpowerpc\-gpopt \-mno\-powerpc\-gpopt \&\-mpowerpc\-gfxopt \-mno\-powerpc\-gfxopt \&\-mnew\-mnemonics \-mold\-mnemonics \&\-mfull\-toc \-mminimal\-toc \-mno\-fp\-in\-toc \-mno\-sum\-in\-toc \&\-m64 \-m32 \-mxl\-call \-mno\-xl\-call \-mpe \&\-malign\-power \-malign\-natural \&\-msoft\-float \-mhard\-float \-mmultiple \-mno\-multiple \&\-mstring \-mno\-string \-mupdate \-mno\-update \&\-mfused\-madd \-mno\-fused\-madd \-mbit\-align \-mno\-bit\-align \&\-mstrict\-align \-mno\-strict\-align \-mrelocatable \&\-mno\-relocatable \-mrelocatable\-lib \-mno\-relocatable\-lib \&\-mtoc \-mno\-toc \-mlittle \-mlittle\-endian \-mbig \-mbig\-endian \&\-mdynamic\-no\-pic \&\-mprioritize\-restricted\-insns=\fR\fIpriority\fR \&\fB\-msched\-costly\-dep=\fR\fIdependence_type\fR \&\fB\-minsert\-sched\-nops=\fR\fIscheme\fR \&\fB\-mcall\-sysv \-mcall\-netbsd \&\-maix\-struct\-return \-msvr4\-struct\-return \&\-mabi=altivec \-mabi=no\-altivec \&\-mabi=spe \-mabi=no\-spe \&\-misel=yes \-misel=no \&\-mspe=yes \-mspe=no \&\-mfloat\-gprs=yes \-mfloat\-gprs=no \&\-mprototype \-mno\-prototype \&\-msim \-mmvme \-mads \-myellowknife \-memb \-msdata \&\-msdata=\fR\fIopt\fR \fB\-mvxworks \-mwindiss \-G\fR \fInum\fR \fB\-pthread\fR .Sp \&\fIDarwin Options\fR \&\fB\-all_load \-allowable_client \-arch \-arch_errors_fatal \&\-arch_only \-bind_at_load \-bundle \-bundle_loader \&\-client_name \-compatibility_version \-current_version \&\-dependency\-file \-dylib_file \-dylinker_install_name \&\-dynamic \-dynamiclib \-exported_symbols_list \&\-filelist \-flat_namespace \-force_cpusubtype_ALL \&\-force_flat_namespace \-headerpad_max_install_names \&\-image_base \-init \-install_name \-keep_private_externs \&\-multi_module \-multiply_defined \-multiply_defined_unused \&\-noall_load \-nofixprebinding \-nomultidefs \-noprebind \-noseglinkedit \&\-pagezero_size \-prebind \-prebind_all_twolevel_modules \&\-private_bundle \-read_only_relocs \-sectalign \&\-sectobjectsymbols \-whyload \-seg1addr \&\-sectcreate \-sectobjectsymbols \-sectorder \&\-seg_addr_table \-seg_addr_table_filename \-seglinkedit \&\-segprot \-segs_read_only_addr \-segs_read_write_addr \&\-single_module \-static \-sub_library \-sub_umbrella \&\-twolevel_namespace \-umbrella \-undefined \&\-unexported_symbols_list \-weak_reference_mismatches \&\-whatsloaded\fR .Sp \&\fI\s-1MIPS\s0 Options\fR \&\fB\-EL \-EB \-march=\fR\fIarch\fR \fB\-mtune=\fR\fIarch\fR \&\fB\-mips1 \-mips2 \-mips3 \-mips4 \-mips32 \-mips32r2 \-mips64 \&\-mips16 \-mno\-mips16 \-mabi=\fR\fIabi\fR \fB\-mabicalls \-mno\-abicalls \&\-mxgot \-mno\-xgot \-membedded\-pic \-mno\-embedded\-pic \&\-mgp32 \-mgp64 \-mfp32 \-mfp64 \-mhard\-float \-msoft\-float \&\-msingle\-float \-mdouble\-float \-mint64 \-mlong64 \-mlong32 \&\-G\fR\fInum\fR \fB\-membedded\-data \-mno\-embedded\-data \&\-muninit\-const\-in\-rodata \-mno\-uninit\-const\-in\-rodata \&\-msplit\-addresses \-mno\-split\-addresses \&\-mexplicit\-relocs \-mno\-explicit\-relocs \&\-mrnames \-mno\-rnames \&\-mcheck\-zero\-division \-mno\-check\-zero\-division \&\-mmemcpy \-mno\-memcpy \-mlong\-calls \-mno\-long\-calls \&\-mmad \-mno\-mad \-mfused\-madd \-mno\-fused\-madd \-nocpp \&\-mfix\-sb1 \-mno\-fix\-sb1 \-mflush\-func=\fR\fIfunc\fR \&\fB\-mno\-flush\-func \-mbranch\-likely \-mno\-branch\-likely\fR .Sp \&\fIi386 and x86\-64 Options\fR \&\fB\-mtune=\fR\fIcpu-type\fR \fB\-march=\fR\fIcpu-type\fR \&\fB\-mfpmath=\fR\fIunit\fR \&\fB\-masm=\fR\fIdialect\fR \fB\-mno\-fancy\-math\-387 \&\-mno\-fp\-ret\-in\-387 \-msoft\-float \-msvr3\-shlib \&\-mno\-wide\-multiply \-mrtd \-malign\-double \&\-mpreferred\-stack\-boundary=\fR\fInum\fR \&\fB\-mmmx \-msse \-msse2 \-msse3 \-m3dnow \&\-mthreads \-mno\-align\-stringops \-minline\-all\-stringops \&\-mpush\-args \-maccumulate\-outgoing\-args \-m128bit\-long\-double \&\-m96bit\-long\-double \-mregparm=\fR\fInum\fR \fB\-momit\-leaf\-frame\-pointer \&\-mno\-red\-zone \-mno\-tls\-direct\-seg\-refs \&\-mcmodel=\fR\fIcode-model\fR \&\fB\-m32 \-m64\fR .Sp \&\fI\s-1HPPA\s0 Options\fR \&\fB\-march=\fR\fIarchitecture-type\fR \&\fB\-mbig\-switch \-mdisable\-fpregs \-mdisable\-indexing \&\-mfast\-indirect\-calls \-mgas \-mgnu\-ld \-mhp\-ld \&\-mjump\-in\-delay \-mlinker\-opt \-mlong\-calls \&\-mlong\-load\-store \-mno\-big\-switch \-mno\-disable\-fpregs \&\-mno\-disable\-indexing \-mno\-fast\-indirect\-calls \-mno\-gas \&\-mno\-jump\-in\-delay \-mno\-long\-load\-store \&\-mno\-portable\-runtime \-mno\-soft\-float \&\-mno\-space\-regs \-msoft\-float \-mpa\-risc\-1\-0 \&\-mpa\-risc\-1\-1 \-mpa\-risc\-2\-0 \-mportable\-runtime \&\-mschedule=\fR\fIcpu-type\fR \fB\-mspace\-regs \-msio \-mwsio \&\-nolibdld \-static \-threads\fR .Sp \&\fIIntel 960 Options\fR \&\fB\-m\fR\fIcpu-type\fR \fB\-masm\-compat \-mclean\-linkage \&\-mcode\-align \-mcomplex\-addr \-mleaf\-procedures \&\-mic\-compat \-mic2.0\-compat \-mic3.0\-compat \&\-mintel\-asm \-mno\-clean\-linkage \-mno\-code\-align \&\-mno\-complex\-addr \-mno\-leaf\-procedures \&\-mno\-old\-align \-mno\-strict\-align \-mno\-tail\-call \&\-mnumerics \-mold\-align \-msoft\-float \-mstrict\-align \&\-mtail\-call\fR .Sp \&\fI\s-1DEC\s0 Alpha Options\fR \&\fB\-mno\-fp\-regs \-msoft\-float \-malpha\-as \-mgas \&\-mieee \-mieee\-with\-inexact \-mieee\-conformant \&\-mfp\-trap\-mode=\fR\fImode\fR \fB\-mfp\-rounding\-mode=\fR\fImode\fR \&\fB\-mtrap\-precision=\fR\fImode\fR \fB\-mbuild\-constants \&\-mcpu=\fR\fIcpu-type\fR \fB\-mtune=\fR\fIcpu-type\fR \&\fB\-mbwx \-mmax \-mfix \-mcix \&\-mfloat\-vax \-mfloat\-ieee \&\-mexplicit\-relocs \-msmall\-data \-mlarge\-data \&\-msmall\-text \-mlarge\-text \&\-mmemory\-latency=\fR\fItime\fR .Sp \&\fI\s-1DEC\s0 Alpha/VMS Options\fR \&\fB\-mvms\-return\-codes\fR .Sp \&\fIH8/300 Options\fR \&\fB\-mrelax \-mh \-ms \-mn \-mint32 \-malign\-300\fR .Sp \&\fI\s-1SH\s0 Options\fR \&\fB\-m1 \-m2 \-m2e \-m3 \-m3e \&\-m4\-nofpu \-m4\-single\-only \-m4\-single \-m4 \&\-m5\-64media \-m5\-64media\-nofpu \&\-m5\-32media \-m5\-32media\-nofpu \&\-m5\-compact \-m5\-compact\-nofpu \&\-mb \-ml \-mdalign \-mrelax \&\-mbigtable \-mfmovd \-mhitachi \-mnomacsave \&\-mieee \-misize \-mpadstruct \-mspace \&\-mprefergot \-musermode\fR .Sp \&\fISystem V Options\fR \&\fB\-Qy \-Qn \-YP,\fR\fIpaths\fR \fB\-Ym,\fR\fIdir\fR .Sp \&\fI\s-1ARC\s0 Options\fR \&\fB\-EB \-EL \&\-mmangle\-cpu \-mcpu=\fR\fIcpu\fR \fB\-mtext=\fR\fItext-section\fR \&\fB\-mdata=\fR\fIdata-section\fR \fB\-mrodata=\fR\fIreadonly-data-section\fR .Sp \&\fITMS320C3x/C4x Options\fR \&\fB\-mcpu=\fR\fIcpu\fR \fB\-mbig \-msmall \-mregparm \-mmemparm \&\-mfast\-fix \-mmpyi \-mbk \-mti \-mdp\-isr\-reload \&\-mrpts=\fR\fIcount\fR \fB\-mrptb \-mdb \-mloop\-unsigned \&\-mparallel\-insns \-mparallel\-mpy \-mpreserve\-float\fR .Sp \&\fIV850 Options\fR \&\fB\-mlong\-calls \-mno\-long\-calls \-mep \-mno\-ep \&\-mprolog\-function \-mno\-prolog\-function \-mspace \&\-mtda=\fR\fIn\fR \fB\-msda=\fR\fIn\fR \fB\-mzda=\fR\fIn\fR \&\fB\-mapp\-regs \-mno\-app\-regs \&\-mdisable\-callt \-mno\-disable\-callt \&\-mv850e1 \&\-mv850e \&\-mv850 \-mbig\-switch\fR .Sp \&\fI\s-1NS32K\s0 Options\fR \&\fB\-m32032 \-m32332 \-m32532 \-m32081 \-m32381 \&\-mmult\-add \-mnomult\-add \-msoft\-float \-mrtd \-mnortd \&\-mregparam \-mnoregparam \-msb \-mnosb \&\-mbitfield \-mnobitfield \-mhimem \-mnohimem\fR .Sp \&\fI\s-1AVR\s0 Options\fR \&\fB\-mmcu=\fR\fImcu\fR \fB\-msize \-minit\-stack=\fR\fIn\fR \fB\-mno\-interrupts \&\-mcall\-prologues \-mno\-tablejump \-mtiny\-stack\fR .Sp \&\fIMCore Options\fR \&\fB\-mhardlit \-mno\-hardlit \-mdiv \-mno\-div \-mrelax\-immediates \&\-mno\-relax\-immediates \-mwide\-bitfields \-mno\-wide\-bitfields \&\-m4byte\-functions \-mno\-4byte\-functions \-mcallgraph\-data \&\-mno\-callgraph\-data \-mslow\-bytes \-mno\-slow\-bytes \-mno\-lsim \&\-mlittle\-endian \-mbig\-endian \-m210 \-m340 \-mstack\-increment\fR .Sp \&\fI\s-1MMIX\s0 Options\fR \&\fB\-mlibfuncs \-mno\-libfuncs \-mepsilon \-mno\-epsilon \-mabi=gnu \&\-mabi=mmixware \-mzero\-extend \-mknuthdiv \-mtoplevel\-symbols \&\-melf \-mbranch\-predict \-mno\-branch\-predict \-mbase\-addresses \&\-mno\-base\-addresses \-msingle\-exit \-mno\-single\-exit\fR .Sp \&\fI\s-1IA\-64\s0 Options\fR \&\fB\-mbig\-endian \-mlittle\-endian \-mgnu\-as \-mgnu\-ld \-mno\-pic \&\-mvolatile\-asm\-stop \-mb\-step \-mregister\-names \-mno\-sdata \&\-mconstant\-gp \-mauto\-pic \-minline\-float\-divide\-min\-latency \&\-minline\-float\-divide\-max\-throughput \&\-minline\-int\-divide\-min\-latency \&\-minline\-int\-divide\-max\-throughput \-mno\-dwarf2\-asm \&\-mfixed\-range=\fR\fIregister-range\fR .Sp \&\fID30V Options\fR \&\fB\-mextmem \-mextmemory \-monchip \-mno\-asm\-optimize \&\-masm\-optimize \-mbranch\-cost=\fR\fIn\fR \fB\-mcond\-exec=\fR\fIn\fR .Sp \&\fIS/390 and zSeries Options\fR \&\fB\-mtune=\fR\fIcpu-type\fR \fB\-march=\fR\fIcpu-type\fR \&\fB\-mhard\-float \-msoft\-float \-mbackchain \-mno\-backchain \&\-msmall\-exec \-mno\-small\-exec \-mmvcle \-mno\-mvcle \&\-m64 \-m31 \-mdebug \-mno\-debug \-mesa \-mzarch \-mfused\-madd \-mno\-fused\-madd\fR .Sp \&\fI\s-1CRIS\s0 Options\fR \&\fB\-mcpu=\fR\fIcpu\fR \fB\-march=\fR\fIcpu\fR \fB\-mtune=\fR\fIcpu\fR \&\fB\-mmax\-stack\-frame=\fR\fIn\fR \fB\-melinux\-stacksize=\fR\fIn\fR \&\fB\-metrax4 \-metrax100 \-mpdebug \-mcc\-init \-mno\-side\-effects \&\-mstack\-align \-mdata\-align \-mconst\-align \&\-m32\-bit \-m16\-bit \-m8\-bit \-mno\-prologue\-epilogue \-mno\-gotplt \&\-melf \-maout \-melinux \-mlinux \-sim \-sim2 \&\-mmul\-bug\-workaround \-mno\-mul\-bug\-workaround\fR .Sp \&\fI\s-1PDP\-11\s0 Options\fR \&\fB\-mfpu \-msoft\-float \-mac0 \-mno\-ac0 \-m40 \-m45 \-m10 \&\-mbcopy \-mbcopy\-builtin \-mint32 \-mno\-int16 \&\-mint16 \-mno\-int32 \-mfloat32 \-mno\-float64 \&\-mfloat64 \-mno\-float32 \-mabshi \-mno\-abshi \&\-mbranch\-expensive \-mbranch\-cheap \&\-msplit \-mno\-split \-munix\-asm \-mdec\-asm\fR .Sp \&\fIXstormy16 Options\fR \&\fB\-msim\fR .Sp \&\fIXtensa Options\fR \&\fB\-mconst16 \-mno\-const16 \&\-mfused\-madd \-mno\-fused\-madd \&\-mtext\-section\-literals \-mno\-text\-section\-literals \&\-mtarget\-align \-mno\-target\-align \&\-mlongcalls \-mno\-longcalls\fR .Sp \&\fI\s-1FRV\s0 Options\fR \&\fB\-mgpr\-32 \-mgpr\-64 \-mfpr\-32 \-mfpr\-64 \&\-mhard\-float \-msoft\-float \&\-malloc\-cc \-mfixed\-cc \-mdword \-mno\-dword \&\-mdouble \-mno\-double \&\-mmedia \-mno\-media \-mmuladd \-mno\-muladd \&\-mlibrary\-pic \-macc\-4 \-macc\-8 \&\-mpack \-mno\-pack \-mno\-eflags \-mcond\-move \-mno\-cond\-move \&\-mscc \-mno\-scc \-mcond\-exec \-mno\-cond\-exec \&\-mvliw\-branch \-mno\-vliw\-branch \&\-mmulti\-cond\-exec \-mno\-multi\-cond\-exec \-mnested\-cond\-exec \&\-mno\-nested\-cond\-exec \-mtomcat\-stats \&\-mcpu=\fR\fIcpu\fR .IP "\fICode Generation Options\fR" 4 .IX Item "Code Generation Options" \&\fB\-fcall\-saved\-\fR\fIreg\fR \fB\-fcall\-used\-\fR\fIreg\fR \&\fB\-ffixed\-\fR\fIreg\fR \fB\-fexceptions \&\-fnon\-call\-exceptions \-funwind\-tables \&\-fasynchronous\-unwind\-tables \&\-finhibit\-size\-directive \-finstrument\-functions \&\-fno\-common \-fno\-ident \&\-fpcc\-struct\-return \-fpic \-fPIC \-fpie \-fPIE \&\-freg\-struct\-return \-fshared\-data \-fshort\-enums \&\-fshort\-double \-fshort\-wchar \&\-fverbose\-asm \-fpack\-struct \-fstack\-check \&\-fstack\-limit\-register=\fR\fIreg\fR \fB\-fstack\-limit\-symbol=\fR\fIsym\fR \&\fB\-fargument\-alias \-fargument\-noalias \&\-fargument\-noalias\-global \-fleading\-underscore \&\-ftls\-model=\fR\fImodel\fR \&\fB\-ftrapv \-fwrapv \-fbounds\-check\fR .Sh "Options Controlling the Kind of Output" .IX Subsection "Options Controlling the Kind of Output" Compilation can involve up to four stages: preprocessing, compilation proper, assembly and linking, always in that order. \s-1GCC\s0 is capable of preprocessing and compiling several files either into several assembler input files, or into one assembler input file; then each assembler input file produces an object file, and linking combines all the object files (those newly compiled, and those specified as input) into an executable file. .PP For any given input file, the file name suffix determines what kind of compilation is done: .IP "\fIfile\fR\fB.c\fR" 4 .IX Item "file.c" C source code which must be preprocessed. .IP "\fIfile\fR\fB.i\fR" 4 .IX Item "file.i" C source code which should not be preprocessed. .IP "\fIfile\fR\fB.ii\fR" 4 .IX Item "file.ii" \&\*(C+ source code which should not be preprocessed. .IP "\fIfile\fR\fB.m\fR" 4 .IX Item "file.m" Objective-C source code. Note that you must link with the library \&\fIlibobjc.a\fR to make an Objective-C program work. .IP "\fIfile\fR\fB.mi\fR" 4 .IX Item "file.mi" Objective-C source code which should not be preprocessed. .IP "\fIfile\fR\fB.h\fR" 4 .IX Item "file.h" C or \*(C+ header file to be turned into a precompiled header. .IP "\fIfile\fR\fB.cc\fR" 4 .IX Item "file.cc" .PD 0 .IP "\fIfile\fR\fB.cp\fR" 4 .IX Item "file.cp" .IP "\fIfile\fR\fB.cxx\fR" 4 .IX Item "file.cxx" .IP "\fIfile\fR\fB.cpp\fR" 4 .IX Item "file.cpp" .IP "\fIfile\fR\fB.CPP\fR" 4 .IX Item "file.CPP" .IP "\fIfile\fR\fB.c++\fR" 4 .IX Item "file.c++" .IP "\fIfile\fR\fB.C\fR" 4 .IX Item "file.C" .PD \&\*(C+ source code which must be preprocessed. Note that in \fB.cxx\fR, the last two letters must both be literally \fBx\fR. Likewise, \&\fB.C\fR refers to a literal capital C. .IP "\fIfile\fR\fB.hh\fR" 4 .IX Item "file.hh" .PD 0 .IP "\fIfile\fR\fB.H\fR" 4 .IX Item "file.H" .PD \&\*(C+ header file to be turned into a precompiled header. .IP "\fIfile\fR\fB.f\fR" 4 .IX Item "file.f" .PD 0 .IP "\fIfile\fR\fB.for\fR" 4 .IX Item "file.for" .IP "\fIfile\fR\fB.FOR\fR" 4 .IX Item "file.FOR" .PD Fortran source code which should not be preprocessed. .IP "\fIfile\fR\fB.F\fR" 4 .IX Item "file.F" .PD 0 .IP "\fIfile\fR\fB.fpp\fR" 4 .IX Item "file.fpp" .IP "\fIfile\fR\fB.FPP\fR" 4 .IX Item "file.FPP" .PD Fortran source code which must be preprocessed (with the traditional preprocessor). .IP "\fIfile\fR\fB.r\fR" 4 .IX Item "file.r" Fortran source code which must be preprocessed with a \s-1RATFOR\s0 preprocessor (not included with \s-1GCC\s0). .IP "\fIfile\fR\fB.ads\fR" 4 .IX Item "file.ads" Ada source code file which contains a library unit declaration (a declaration of a package, subprogram, or generic, or a generic instantiation), or a library unit renaming declaration (a package, generic, or subprogram renaming declaration). Such files are also called \fIspecs\fR. .IP "\fIfile\fR\fB.adb\fR" 4 .IX Item "file.adb" Ada source code file containing a library unit body (a subprogram or package body). Such files are also called \fIbodies\fR. .IP "\fIfile\fR\fB.s\fR" 4 .IX Item "file.s" Assembler code. .IP "\fIfile\fR\fB.S\fR" 4 .IX Item "file.S" Assembler code which must be preprocessed. .IP "\fIother\fR" 4 .IX Item "other" An object file to be fed straight into linking. Any file name with no recognized suffix is treated this way. .PP You can specify the input language explicitly with the \fB\-x\fR option: .IP "\fB\-x\fR \fIlanguage\fR" 4 .IX Item "-x language" Specify explicitly the \fIlanguage\fR for the following input files (rather than letting the compiler choose a default based on the file name suffix). This option applies to all following input files until the next \fB\-x\fR option. Possible values for \fIlanguage\fR are: .Sp .Vb 8 \& c c-header cpp-output \& c++ c++-header c++-cpp-output \& objective-c objective-c-header objc-cpp-output \& assembler assembler-with-cpp \& ada \& f77 f77-cpp-input ratfor \& java \& treelang .Ve .IP "\fB\-x none\fR" 4 .IX Item "-x none" Turn off any specification of a language, so that subsequent files are handled according to their file name suffixes (as they are if \fB\-x\fR has not been used at all). .IP "\fB\-pass\-exit\-codes\fR" 4 .IX Item "-pass-exit-codes" Normally the \fBgcc\fR program will exit with the code of 1 if any phase of the compiler returns a non-success return code. If you specify \&\fB\-pass\-exit\-codes\fR, the \fBgcc\fR program will instead return with numerically highest error produced by any phase that returned an error indication. .PP If you only want some of the stages of compilation, you can use \&\fB\-x\fR (or filename suffixes) to tell \fBgcc\fR where to start, and one of the options \fB\-c\fR, \fB\-S\fR, or \fB\-E\fR to say where \&\fBgcc\fR is to stop. Note that some combinations (for example, \&\fB\-x cpp-output \-E\fR) instruct \fBgcc\fR to do nothing at all. .IP "\fB\-c\fR" 4 .IX Item "-c" Compile or assemble the source files, but do not link. The linking stage simply is not done. The ultimate output is in the form of an object file for each source file. .Sp By default, the object file name for a source file is made by replacing the suffix \fB.c\fR, \fB.i\fR, \fB.s\fR, etc., with \fB.o\fR. .Sp Unrecognized input files, not requiring compilation or assembly, are ignored. .IP "\fB\-S\fR" 4 .IX Item "-S" Stop after the stage of compilation proper; do not assemble. The output is in the form of an assembler code file for each non-assembler input file specified. .Sp By default, the assembler file name for a source file is made by replacing the suffix \fB.c\fR, \fB.i\fR, etc., with \fB.s\fR. .Sp Input files that don't require compilation are ignored. .IP "\fB\-E\fR" 4 .IX Item "-E" Stop after the preprocessing stage; do not run the compiler proper. The output is in the form of preprocessed source code, which is sent to the standard output. .Sp Input files which don't require preprocessing are ignored. .IP "\fB\-o\fR \fIfile\fR" 4 .IX Item "-o file" Place output in file \fIfile\fR. This applies regardless to whatever sort of output is being produced, whether it be an executable file, an object file, an assembler file or preprocessed C code. .Sp If you specify \fB\-o\fR when compiling more than one input file, or you are producing an executable file as output, all the source files on the command line will be compiled at once. .Sp If \fB\-o\fR is not specified, the default is to put an executable file in \fIa.out\fR, the object file for \fI\fIsource\fI.\fIsuffix\fI\fR in \&\fI\fIsource\fI.o\fR, its assembler file in \fI\fIsource\fI.s\fR, and all preprocessed C source on standard output. .IP "\fB\-v\fR" 4 .IX Item "-v" Print (on 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. .IP "\fB\-###\fR" 4 .IX Item "-###" Like \fB\-v\fR except the commands are not executed and all command arguments are quoted. This is useful for shell scripts to capture the driver-generated command lines. .IP "\fB\-pipe\fR" 4 .IX Item "-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 is unable to read from a pipe; but the \s-1GNU\s0 assembler has no trouble. .IP "\fB\-\-help\fR" 4 .IX Item "--help" Print (on the standard output) a description of the command line options understood by \fBgcc\fR. If the \fB\-v\fR option is also specified then \fB\-\-help\fR will also be passed on to the various processes invoked by \fBgcc\fR, so that they can display the command line options they accept. If the \fB\-Wextra\fR option is also specified then command line options which have no documentation associated with them will also be displayed. .IP "\fB\-\-target\-help\fR" 4 .IX Item "--target-help" Print (on the standard output) a description of target specific command line options for each tool. .IP "\fB\-\-version\fR" 4 .IX Item "--version" Display the version number and copyrights of the invoked \s-1GCC\s0. .Sh "Compiling \*(C+ Programs" .IX Subsection "Compiling Programs" \&\*(C+ source files conventionally use one of the suffixes \fB.C\fR, \&\fB.cc\fR, \fB.cpp\fR, \fB.CPP\fR, \fB.c++\fR, \fB.cp\fR, or \&\fB.cxx\fR; \*(C+ header files often use \fB.hh\fR or \fB.H\fR; and preprocessed \*(C+ files use the suffix \fB.ii\fR. \s-1GCC\s0 recognizes files with these names and compiles them as \*(C+ programs even if you call the compiler the same way as for compiling C programs (usually with the name \fBgcc\fR). .PP However, \*(C+ programs often require class libraries as well as a compiler that understands the \*(C+ language\-\-\-and under some circumstances, you might want to compile programs or header files from standard input, or otherwise without a suffix that flags them as \*(C+ programs. You might also like to precompile a C header file with a \&\fB.h\fR extension to be used in \*(C+ compilations. \fBg++\fR is a program that calls \s-1GCC\s0 with the default language set to \*(C+, and automatically specifies linking against the \*(C+ library. On many systems, \fBg++\fR is also installed with the name \fBc++\fR. .PP When you compile \*(C+ programs, you may specify many of the same command-line options that you use for compiling programs in any language; or command-line options meaningful for C and related languages; or options that are meaningful only for \*(C+ programs. .Sh "Options Controlling C Dialect" .IX Subsection "Options Controlling C Dialect" The following options control the dialect of C (or languages derived from C, such as \*(C+ and Objective\-C) that the compiler accepts: .IP "\fB\-ansi\fR" 4 .IX Item "-ansi" In C mode, support all \s-1ISO\s0 C90 programs. In \*(C+ mode, remove \s-1GNU\s0 extensions that conflict with \s-1ISO\s0 \*(C+. .Sp This turns off certain features of \s-1GCC\s0 that are incompatible with \s-1ISO\s0 C90 (when compiling C code), or of standard \*(C+ (when compiling \*(C+ code), such as the \f(CW\*(C`asm\*(C'\fR and \f(CW\*(C`typeof\*(C'\fR keywords, and predefined macros such as \f(CW\*(C`unix\*(C'\fR and \f(CW\*(C`vax\*(C'\fR that identify the type of system you are using. It also enables the undesirable and rarely used \s-1ISO\s0 trigraph feature. For the C compiler, it disables recognition of \*(C+ style \fB//\fR comments as well as the \f(CW\*(C`inline\*(C'\fR keyword. .Sp The alternate keywords \f(CW\*(C`_\|_asm_\|_\*(C'\fR, \f(CW\*(C`_\|_extension_\|_\*(C'\fR, \&\f(CW\*(C`_\|_inline_\|_\*(C'\fR and \f(CW\*(C`_\|_typeof_\|_\*(C'\fR continue to work despite \&\fB\-ansi\fR. You would not want to use them in an \s-1ISO\s0 C program, of course, but it is useful to put them in header files that might be included in compilations done with \fB\-ansi\fR. Alternate predefined macros such as \f(CW\*(C`_\|_unix_\|_\*(C'\fR and \f(CW\*(C`_\|_vax_\|_\*(C'\fR are also available, with or without \fB\-ansi\fR. .Sp The \fB\-ansi\fR option does not cause non-ISO programs to be rejected gratuitously. For that, \fB\-pedantic\fR is required in addition to \fB\-ansi\fR. .Sp The macro \f(CW\*(C`_\|_STRICT_ANSI_\|_\*(C'\fR is predefined when the \fB\-ansi\fR option is used. Some header files may notice this macro and refrain from declaring certain functions or defining certain macros that the \&\s-1ISO\s0 standard doesn't call for; this is to avoid interfering with any programs that might use these names for other things. .Sp Functions which would normally be built in but do not have semantics defined by \s-1ISO\s0 C (such as \f(CW\*(C`alloca\*(C'\fR and \f(CW\*(C`ffs\*(C'\fR) are not built-in functions with \fB\-ansi\fR is used. .IP "\fB\-std=\fR" 4 .IX Item "-std=" Determine the language standard. This option is currently only supported when compiling C or \*(C+. A value for this option must be provided; possible values are .RS 4 .IP "\fBc89\fR" 4 .IX Item "c89" .PD 0 .IP "\fBiso9899:1990\fR" 4 .IX Item "iso9899:1990" .PD \&\s-1ISO\s0 C90 (same as \fB\-ansi\fR). .IP "\fBiso9899:199409\fR" 4 .IX Item "iso9899:199409" \&\s-1ISO\s0 C90 as modified in amendment 1. .IP "\fBc99\fR" 4 .IX Item "c99" .PD 0 .IP "\fBc9x\fR" 4 .IX Item "c9x" .IP "\fBiso9899:1999\fR" 4 .IX Item "iso9899:1999" .IP "\fBiso9899:199x\fR" 4 .IX Item "iso9899:199x" .PD \&\s-1ISO\s0 C99. Note that this standard is not yet fully supported; see <\fBhttp://gcc.gnu.org/gcc\-3.4/c99status.html\fR> for more information. The names \fBc9x\fR and \fBiso9899:199x\fR are deprecated. .IP "\fBgnu89\fR" 4 .IX Item "gnu89" Default, \s-1ISO\s0 C90 plus \s-1GNU\s0 extensions (including some C99 features). .IP "\fBgnu99\fR" 4 .IX Item "gnu99" .PD 0 .IP "\fBgnu9x\fR" 4 .IX Item "gnu9x" .PD \&\s-1ISO\s0 C99 plus \s-1GNU\s0 extensions. When \s-1ISO\s0 C99 is fully implemented in \s-1GCC\s0, this will become the default. The name \fBgnu9x\fR is deprecated. .IP "\fBc++98\fR" 4 .IX Item "c++98" The 1998 \s-1ISO\s0 \*(C+ standard plus amendments. .IP "\fBgnu++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 .Sp Even when this option is not specified, you can still use some of the features of newer standards in so far as they do not conflict with previous C standards. For example, you may use \f(CW\*(C`_\|_restrict_\|_\*(C'\fR even when \fB\-std=c99\fR is not specified. .Sp The \fB\-std\fR options specifying some version of \s-1ISO\s0 C have the same effects as \fB\-ansi\fR, except that features that were not in \s-1ISO\s0 C90 but are in the specified version (for example, \fB//\fR comments and the \f(CW\*(C`inline\*(C'\fR keyword in \s-1ISO\s0 C99) are not disabled. .RE .IP "\fB\-aux\-info\fR \fIfilename\fR" 4 .IX Item "-aux-info filename" Output to the given filename prototyped declarations for all functions declared and/or defined in a translation unit, including those in header files. This option is silently ignored in any language other than C. .Sp Besides declarations, the file indicates, in comments, the origin of each declaration (source file and line), whether the declaration was implicit, prototyped or unprototyped (\fBI\fR, \fBN\fR for new or \&\fBO\fR for old, respectively, in the first character after the line number and the colon), and whether it came from a declaration or a definition (\fBC\fR or \fBF\fR, respectively, in the following character). In the case of function definitions, a K&R\-style list of arguments followed by their declarations is also provided, inside comments, after the declaration. .IP "\fB\-fno\-asm\fR" 4 .IX Item "-fno-asm" Do not recognize \f(CW\*(C`asm\*(C'\fR, \f(CW\*(C`inline\*(C'\fR or \f(CW\*(C`typeof\*(C'\fR as a keyword, so that code can use these words as identifiers. You can use the keywords \f(CW\*(C`_\|_asm_\|_\*(C'\fR, \f(CW\*(C`_\|_inline_\|_\*(C'\fR and \f(CW\*(C`_\|_typeof_\|_\*(C'\fR instead. \fB\-ansi\fR implies \fB\-fno\-asm\fR. .Sp In \*(C+, this switch only affects the \f(CW\*(C`typeof\*(C'\fR keyword, since \&\f(CW\*(C`asm\*(C'\fR and \f(CW\*(C`inline\*(C'\fR are standard keywords. You may want to use the \fB\-fno\-gnu\-keywords\fR flag instead, which has the same effect. In C99 mode (\fB\-std=c99\fR or \fB\-std=gnu99\fR), this switch only affects the \f(CW\*(C`asm\*(C'\fR and \f(CW\*(C`typeof\*(C'\fR keywords, since \&\f(CW\*(C`inline\*(C'\fR is a standard keyword in \s-1ISO\s0 C99. .IP "\fB\-fno\-builtin\fR" 4 .IX Item "-fno-builtin" .PD 0 .IP "\fB\-fno\-builtin\-\fR\fIfunction\fR" 4 .IX Item "-fno-builtin-function" .PD Don't recognize built-in functions that do not begin with \&\fB_\|_builtin_\fR as prefix. .Sp \&\s-1GCC\s0 normally generates special code to handle certain built-in functions more efficiently; for instance, calls to \f(CW\*(C`alloca\*(C'\fR may become single instructions that adjust the stack directly, and calls to \f(CW\*(C`memcpy\*(C'\fR may become inline copy loops. The resulting code is often both smaller and faster, but since the function calls no longer appear as such, you cannot set a breakpoint on those calls, nor can you change the behavior of the functions by linking with a different library. .Sp With the \fB\-fno\-builtin\-\fR\fIfunction\fR option only the built-in function \fIfunction\fR is disabled. \fIfunction\fR must not begin with \fB_\|_builtin_\fR. If a function is named this is not built-in in this version of \s-1GCC\s0, this option is ignored. There is no corresponding \&\fB\-fbuiltin\-\fR\fIfunction\fR option; if you wish to enable built-in functions selectively when using \fB\-fno\-builtin\fR or \&\fB\-ffreestanding\fR, you may define macros such as: .Sp .Vb 2 \& #define abs(n) __builtin_abs ((n)) \& #define strcpy(d, s) __builtin_strcpy ((d), (s)) .Ve .IP "\fB\-fhosted\fR" 4 .IX Item "-fhosted" Assert that compilation takes place in a hosted environment. This implies \&\fB\-fbuiltin\fR. A hosted environment is one in which the entire standard library is available, and in which \f(CW\*(C`main\*(C'\fR has a return type of \f(CW\*(C`int\*(C'\fR. Examples are nearly everything except a kernel. This is equivalent to \fB\-fno\-freestanding\fR. .IP "\fB\-ffreestanding\fR" 4 .IX Item "-ffreestanding" Assert that compilation takes place in a freestanding environment. This implies \fB\-fno\-builtin\fR. A freestanding environment is one in which the standard library may not exist, and program startup may not necessarily be at \f(CW\*(C`main\*(C'\fR. The most obvious example is an \s-1OS\s0 kernel. This is equivalent to \fB\-fno\-hosted\fR. .IP "\fB\-fms\-extensions\fR" 4 .IX Item "-fms-extensions" Accept some non-standard constructs used in Microsoft header files. .IP "\fB\-trigraphs\fR" 4 .IX Item "-trigraphs" Support \s-1ISO\s0 C trigraphs. The \fB\-ansi\fR option (and \fB\-std\fR options for strict \s-1ISO\s0 C conformance) implies \fB\-trigraphs\fR. .IP "\fB\-no\-integrated\-cpp\fR" 4 .IX Item "-no-integrated-cpp" Performs a compilation in two passes: preprocessing and compiling. This option allows a user supplied \*(L"cc1\*(R", \*(L"cc1plus\*(R", or \*(L"cc1obj\*(R" via the \&\fB\-B\fR option. The user supplied compilation step can then add in an additional preprocessing step after normal preprocessing but before compiling. The default is to use the integrated cpp (internal cpp) .Sp The semantics of this option will change if \*(L"cc1\*(R", \*(L"cc1plus\*(R", and \&\*(L"cc1obj\*(R" are merged. .IP "\fB\-traditional\fR" 4 .IX Item "-traditional" .PD 0 .IP "\fB\-traditional\-cpp\fR" 4 .IX Item "-traditional-cpp" .PD Formerly, these options caused \s-1GCC\s0 to attempt to emulate a pre-standard C compiler. They are now only supported with the \fB\-E\fR switch. The preprocessor continues to support a pre-standard mode. See the \s-1GNU\s0 \&\s-1CPP\s0 manual for details. .IP "\fB\-fcond\-mismatch\fR" 4 .IX Item "-fcond-mismatch" Allow conditional expressions with mismatched types in the second and third arguments. The value of such an expression is void. This option is not supported for \*(C+. .IP "\fB\-funsigned\-char\fR" 4 .IX Item "-funsigned-char" Let the type \f(CW\*(C`char\*(C'\fR be unsigned, like \f(CW\*(C`unsigned char\*(C'\fR. .Sp Each kind of machine has a default for what \f(CW\*(C`char\*(C'\fR should be. It is either like \f(CW\*(C`unsigned char\*(C'\fR by default or like \&\f(CW\*(C`signed char\*(C'\fR by default. .Sp Ideally, a portable program should always use \f(CW\*(C`signed char\*(C'\fR or \&\f(CW\*(C`unsigned char\*(C'\fR when it depends on the signedness of an object. But many programs have been written to use plain \f(CW\*(C`char\*(C'\fR 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. .Sp The type \f(CW\*(C`char\*(C'\fR is always a distinct type from each of \&\f(CW\*(C`signed char\*(C'\fR or \f(CW\*(C`unsigned char\*(C'\fR, even though its behavior is always just like one of those two. .IP "\fB\-fsigned\-char\fR" 4 .IX Item "-fsigned-char" Let the type \f(CW\*(C`char\*(C'\fR be signed, like \f(CW\*(C`signed char\*(C'\fR. .Sp Note that this is equivalent to \fB\-fno\-unsigned\-char\fR, which is the negative form of \fB\-funsigned\-char\fR. Likewise, the option \&\fB\-fno\-signed\-char\fR is equivalent to \fB\-funsigned\-char\fR. .IP "\fB\-fsigned\-bitfields\fR" 4 .IX Item "-fsigned-bitfields" .PD 0 .IP "\fB\-funsigned\-bitfields\fR" 4 .IX Item "-funsigned-bitfields" .IP "\fB\-fno\-signed\-bitfields\fR" 4 .IX Item "-fno-signed-bitfields" .IP "\fB\-fno\-unsigned\-bitfields\fR" 4 .IX Item "-fno-unsigned-bitfields" .PD These options control whether a bit-field is signed or unsigned, when the declaration does not use either \f(CW\*(C`signed\*(C'\fR or \f(CW\*(C`unsigned\*(C'\fR. By default, such a bit-field is signed, because this is consistent: the basic integer types such as \f(CW\*(C`int\*(C'\fR are signed types. .IP "\fB\-fwritable\-strings\fR" 4 .IX Item "-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. .Sp Writing into string constants is a very bad idea; ``constants'' should be constant. .Sp This option is deprecated. .Sh "Options Controlling \*(C+ Dialect" .IX Subsection "Options Controlling Dialect" This section describes the command-line options that are only meaningful for \*(C+ programs; but you can also use most of the \s-1GNU\s0 compiler options regardless of what language your program is in. For example, you might compile a file \f(CW\*(C`firstClass.C\*(C'\fR like this: .PP .Vb 1 \& g++ -g -frepo -O -c firstClass.C .Ve .PP In this example, only \fB\-frepo\fR is an option meant only for \*(C+ programs; you can use the other options with any language supported by \s-1GCC\s0. .PP Here is a list of options that are \fIonly\fR for compiling \*(C+ programs: .IP "\fB\-fabi\-version=\fR\fIn\fR" 4 .IX Item "-fabi-version=n" Use version \fIn\fR of the \*(C+ \s-1ABI\s0. Version 2 is the version of the \&\*(C+ \s-1ABI\s0 that first appeared in G++ 3.4. Version 1 is the version of the \*(C+ \s-1ABI\s0 that first appeared in G++ 3.2. Version 0 will always be the version that conforms most closely to the \*(C+ \s-1ABI\s0 specification. Therefore, the \s-1ABI\s0 obtained using version 0 will change as \s-1ABI\s0 bugs are fixed. .Sp The default is version 2. .IP "\fB\-fno\-access\-control\fR" 4 .IX Item "-fno-access-control" Turn off all access checking. This switch is mainly useful for working around bugs in the access control code. .IP "\fB\-fcheck\-new\fR" 4 .IX Item "-fcheck-new" Check that the pointer returned by \f(CW\*(C`operator new\*(C'\fR is non-null before attempting to modify the storage allocated. This check is normally unnecessary because the \*(C+ standard specifies that \&\f(CW\*(C`operator new\*(C'\fR will only return \f(CW0\fR if it is declared \&\fB\f(BIthrow()\fB\fR, in which case the compiler will always check the return value even without this option. In all other cases, when \&\f(CW\*(C`operator new\*(C'\fR has a non-empty exception specification, memory exhaustion is signalled by throwing \f(CW\*(C`std::bad_alloc\*(C'\fR. See also \&\fBnew (nothrow)\fR. .IP "\fB\-fconserve\-space\fR" 4 .IX Item "-fconserve-space" Put uninitialized or runtime-initialized global variables into the common segment, as C does. This saves space in the executable at the cost of not diagnosing duplicate definitions. If you compile with this flag and your program mysteriously crashes after \f(CW\*(C`main()\*(C'\fR has completed, you may have an object that is being destroyed twice because two definitions were merged. .Sp This option is no longer useful on most targets, now that support has been added for putting variables into \s-1BSS\s0 without making them common. .IP "\fB\-fno\-const\-strings\fR" 4 .IX Item "-fno-const-strings" Give string constants type \f(CW\*(C`char *\*(C'\fR instead of type \f(CW\*(C`const char *\*(C'\fR. By default, G++ uses type \f(CW\*(C`const char *\*(C'\fR as required by the standard. Even if you use \fB\-fno\-const\-strings\fR, you cannot actually modify the value of a string constant, unless you also use \&\fB\-fwritable\-strings\fR. .Sp This option might be removed in a future release of G++. For maximum portability, you should structure your code so that it works with string constants that have type \f(CW\*(C`const char *\*(C'\fR. .IP "\fB\-fno\-elide\-constructors\fR" 4 .IX Item "-fno-elide-constructors" The \*(C+ standard allows an implementation to omit creating a temporary which is only used to initialize another object of the same type. Specifying this option disables that optimization, and forces G++ to call the copy constructor in all cases. .IP "\fB\-fno\-enforce\-eh\-specs\fR" 4 .IX Item "-fno-enforce-eh-specs" Don't check for violation of exception specifications at runtime. This option violates the \*(C+ standard, but may be useful for reducing code size in production builds, much like defining \fB\s-1NDEBUG\s0\fR. The compiler will still optimize based on the exception specifications. .IP "\fB\-ffor\-scope\fR" 4 .IX Item "-ffor-scope" .PD 0 .IP "\fB\-fno\-for\-scope\fR" 4 .IX Item "-fno-for-scope" .PD If \fB\-ffor\-scope\fR is specified, the scope of variables declared in a \fIfor-init-statement\fR is limited to the \fBfor\fR loop itself, as specified by the \*(C+ standard. If \fB\-fno\-for\-scope\fR is specified, the scope of variables declared in a \fIfor-init-statement\fR extends to the end of the enclosing scope, as was the case in old versions of G++, and other (traditional) implementations of \*(C+. .Sp The default if neither flag is given to follow the standard, but to allow and give a warning for old-style code that would otherwise be invalid, or have different behavior. .IP "\fB\-fno\-gnu\-keywords\fR" 4 .IX Item "-fno-gnu-keywords" Do not recognize \f(CW\*(C`typeof\*(C'\fR as a keyword, so that code can use this word as an identifier. You can use the keyword \f(CW\*(C`_\|_typeof_\|_\*(C'\fR instead. \&\fB\-ansi\fR implies \fB\-fno\-gnu\-keywords\fR. .IP "\fB\-fno\-implicit\-templates\fR" 4 .IX Item "-fno-implicit-templates" Never emit code for non-inline templates which are instantiated implicitly (i.e. by use); only emit code for explicit instantiations. .IP "\fB\-fno\-implicit\-inline\-templates\fR" 4 .IX Item "-fno-implicit-inline-templates" Don't emit code for implicit instantiations of inline templates, either. The default is to handle inlines differently so that compiles with and without optimization will need the same set of explicit instantiations. .IP "\fB\-fno\-implement\-inlines\fR" 4 .IX Item "-fno-implement-inlines" To save space, do not emit out-of-line copies of inline functions controlled by \fB#pragma implementation\fR. This will cause linker errors if these functions are not inlined everywhere they are called. .IP "\fB\-fms\-extensions\fR" 4 .IX Item "-fms-extensions" Disable pedantic warnings about constructs used in \s-1MFC\s0, such as implicit int and getting a pointer to member function via non-standard syntax. .IP "\fB\-fno\-nonansi\-builtins\fR" 4 .IX Item "-fno-nonansi-builtins" Disable built-in declarations of functions that are not mandated by \&\s-1ANSI/ISO\s0 C. These include \f(CW\*(C`ffs\*(C'\fR, \f(CW\*(C`alloca\*(C'\fR, \f(CW\*(C`_exit\*(C'\fR, \&\f(CW\*(C`index\*(C'\fR, \f(CW\*(C`bzero\*(C'\fR, \f(CW\*(C`conjf\*(C'\fR, and other related functions. .IP "\fB\-fno\-operator\-names\fR" 4 .IX Item "-fno-operator-names" Do not treat the operator name keywords \f(CW\*(C`and\*(C'\fR, \f(CW\*(C`bitand\*(C'\fR, \&\f(CW\*(C`bitor\*(C'\fR, \f(CW\*(C`compl\*(C'\fR, \f(CW\*(C`not\*(C'\fR, \f(CW\*(C`or\*(C'\fR and \f(CW\*(C`xor\*(C'\fR as synonyms as keywords. .IP "\fB\-fno\-optional\-diags\fR" 4 .IX Item "-fno-optional-diags" Disable diagnostics that the standard says a compiler does not need to issue. Currently, the only such diagnostic issued by G++ is the one for a name having multiple meanings within a class. .IP "\fB\-fpermissive\fR" 4 .IX Item "-fpermissive" Downgrade some diagnostics about nonconformant code from errors to warnings. Thus, using \fB\-fpermissive\fR will allow some nonconforming code to compile. .IP "\fB\-frepo\fR" 4 .IX Item "-frepo" Enable automatic template instantiation at link time. This option also implies \fB\-fno\-implicit\-templates\fR. .IP "\fB\-fno\-rtti\fR" 4 .IX Item "-fno-rtti" Disable generation of information about every class with virtual functions for use by the \*(C+ runtime type identification features (\fBdynamic_cast\fR and \fBtypeid\fR). If you don't use those parts of the language, you can save some space by using this flag. Note that exception handling uses the same information, but it will generate it as needed. .IP "\fB\-fstats\fR" 4 .IX Item "-fstats" Emit statistics about front-end processing at the end of the compilation. This information is generally only useful to the G++ development team. .IP "\fB\-ftemplate\-depth\-\fR\fIn\fR" 4 .IX Item "-ftemplate-depth-n" Set the maximum instantiation depth for template classes to \fIn\fR. A limit on the template instantiation depth is needed to detect endless recursions during template class instantiation. \s-1ANSI/ISO\s0 \*(C+ conforming programs must not rely on a maximum depth greater than 17. .IP "\fB\-fuse\-cxa\-atexit\fR" 4 .IX Item "-fuse-cxa-atexit" Register destructors for objects with static storage duration with the \&\f(CW\*(C`_\|_cxa_atexit\*(C'\fR function rather than the \f(CW\*(C`atexit\*(C'\fR function. This option is required for fully standards-compliant handling of static destructors, but will only work if your C library supports \&\f(CW\*(C`_\|_cxa_atexit\*(C'\fR. .IP "\fB\-fno\-weak\fR" 4 .IX Item "-fno-weak" Do not use weak symbol support, even if it is provided by the linker. By default, G++ will use weak symbols if they are available. This option exists only for testing, and should not be used by end\-users; it will result in inferior code and has no benefits. This option may be removed in a future release of G++. .IP "\fB\-nostdinc++\fR" 4 .IX Item "-nostdinc++" Do not search for header files in the standard directories specific to \&\*(C+, but do still search the other standard directories. (This option is used when building the \*(C+ library.) .PP In addition, these optimization, warning, and code generation options have meanings only for \*(C+ programs: .IP "\fB\-fno\-default\-inline\fR" 4 .IX Item "-fno-default-inline" Do not assume \fBinline\fR for functions defined inside a class scope. Note that these functions will have linkage like inline functions; they just won't be inlined by default. .IP "\fB\-Wabi\fR (\*(C+ only)" 4 .IX Item "-Wabi ( only)" Warn when G++ generates code that is probably not compatible with the vendor-neutral \*(C+ \s-1ABI\s0. Although an effort has been made to warn about all such cases, there are probably some cases that are not warned about, even though G++ is generating incompatible code. There may also be cases where warnings are emitted even though the code that is generated will be compatible. .Sp You should rewrite your code to avoid these warnings if you are concerned about the fact that code generated by G++ may not be binary compatible with code generated by other compilers. .Sp The known incompatibilities at this point include: .RS 4 .IP "\(bu" 4 Incorrect handling of tail-padding for bit\-fields. G++ may attempt to pack data into the same byte as a base class. For example: .Sp .Vb 2 \& struct A { virtual void f(); int f1 : 1; }; \& struct B : public A { int f2 : 1; }; .Ve .Sp In this case, G++ will place \f(CW\*(C`B::f2\*(C'\fR into the same byte as\f(CW\*(C`A::f1\*(C'\fR; other compilers will not. You can avoid this problem by explicitly padding \f(CW\*(C`A\*(C'\fR so that its size is a multiple of the byte size on your platform; that will cause G++ and other compilers to layout \f(CW\*(C`B\*(C'\fR identically. .IP "\(bu" 4 Incorrect handling of tail-padding for virtual bases. G++ does not use tail padding when laying out virtual bases. For example: .Sp .Vb 3 \& struct A { virtual void f(); char c1; }; \& struct B { B(); char c2; }; \& struct C : public A, public virtual B {}; .Ve .Sp In this case, G++ will not place \f(CW\*(C`B\*(C'\fR into the tail-padding for \&\f(CW\*(C`A\*(C'\fR; other compilers will. You can avoid this problem by explicitly padding \f(CW\*(C`A\*(C'\fR so that its size is a multiple of its alignment (ignoring virtual base classes); that will cause G++ and other compilers to layout \f(CW\*(C`C\*(C'\fR identically. .IP "\(bu" 4 Incorrect handling of bit-fields with declared widths greater than that of their underlying types, when the bit-fields appear in a union. For example: .Sp .Vb 1 \& union U { int i : 4096; }; .Ve .Sp Assuming that an \f(CW\*(C`int\*(C'\fR does not have 4096 bits, G++ will make the union too small by the number of bits in an \f(CW\*(C`int\*(C'\fR. .IP "\(bu" 4 Empty classes can be placed at incorrect offsets. For example: .Sp .Vb 1 \& struct A {}; .Ve .Sp .Vb 4 \& struct B { \& A a; \& virtual void f (); \& }; .Ve .Sp .Vb 1 \& struct C : public B, public A {}; .Ve .Sp G++ will place the \f(CW\*(C`A\*(C'\fR base class of \f(CW\*(C`C\*(C'\fR at a nonzero offset; it should be placed at offset zero. G++ mistakenly believes that the \&\f(CW\*(C`A\*(C'\fR data member of \f(CW\*(C`B\*(C'\fR is already at offset zero. .IP "\(bu" 4 Names of template functions whose types involve \f(CW\*(C`typename\*(C'\fR or template template parameters can be mangled incorrectly. .Sp .Vb 2 \& template \& void f(typename Q::X) {} .Ve .Sp .Vb 2 \& template