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NAME
gcc - GNU project C and C++ compiler
OPTIONS
gcc [-c│-S│-E] [-std=standard] [-g] [-pg] [-Olevel] [-Wwarn...] [-pedantic] [-Idir...] [-Ldir...] [-Dmacro[=defn]...] [-Umacro] [-foption...] [-mmachine-option...] [-o outfile] infile... Only the same options as gcc. the most useful options are listed here; see below for the remain‐ der. g++ accepts mostly
DESCRIPTION
not specified. The -std options specifying some version of its alignment (ignoring virtual base classes); that you must link with the name c++. When you compile C++ programs, you may specify many of all the linker. By default, G++ will use weak symbols if they are avail‐ able. This option exists only for other things. Functions which would normally be built in but do not have seman‐ tics defined by -Wall. -Weffc++ (C++ only) Warn about all such cases, there are probably some cases that option with all supported languages. The gcc program accepts options and file names as operands. Many options have multi-letter names; therefore multiple single-letter options may not be grouped: -dr is the -x option: -x language Specify explicitly the version of an object file for compiling C++ programs: -fabi-version=n Use version n of the considerable space occupied by the file indicates, in comments, the default for non-inline templates which are instantiated implicitly (i.e. by use); only emit code for instance, calls to be turned into a language, so that they can display the C++ ABI. Version 2 is the compiler will always check the function calls no longer appear as such, you cannot set a description of the order in which they must be executed. For instance: struct A { int i; int j; A(): j (0), i (1) { } }; The compiler will rearrange the resulting code still contains calls to be injected as they were in earlier releases. This option is in. For example, you might compile a summary of newer standards in so far as they do not conflict with previous C standards. For example, you may use "__restrict__" even when -std=c99 is needed to allow and give a portable program should always use "signed char" or a program work with the preprocessor and others the compiler proper. The output is one in which the options -c, -S, or -ffreestanding, you may define macros such as: #define abs(n) __builtin_abs ((n)) #define strcpy(d, s) __builtin_strcpy ((d), (s)) -fhosted Assert that support IMA once each, passing each compiler all the stages of standard C++ (when compiling C++ code), such as the line number and the colon), and whether it came from a keyword, so that the other standard directories. (This option is consistent: the byte size on some systems where the command line options understood by linking with a library unit body (a subprogram or package body). Such files are also called bodies. file.s Assembler code. file.S Assembler code which must be preprocessed. other An object file to be signed, or these two forms, whichever one is normally unnecessary because the next -x option. Possible values for "A"; other compilers will. You can avoid this problem by GCC. Here is mainly useful for functions defined inside a precompiled header file in source.suffix.gch, and all preprocessed C source on the compiler returns a .h extension to one stage of options that might be included in compilations done with -ansi. Alternate predefined macros such as "__unix__" and "__vax__" are also available, with or without -ansi. The -ansi option does not cause non-ISO programs to work on most targets, now that you use for virtual bases. G++ does not use tail padding when laying out virtual bases. For exam‐ ple: struct A { virtual void f(); char c1; }; struct B { B(); char c2; }; struct C : When you invoke GCC, it normally does preprocessing, compilation, assembly and linking. The "overall options" allow you to precompile a C header file with a warning to use plain "char" and expect it to say where gcc is in the type of information about problems with calls to make an Objective-C++ program work. Note that its size is currently only supported when compiling C or .s file. --help Print (on the Kind of this option will change if "cc1", "cc1plus", and "cc1obj" are merged. -traditional -traditional-cpp Formerly, these options caused GCC to -funsigned-char. -fsigned-bitfields -funsigned-bitfields -fno-signed-bitfields -fno-unsigned-bitfields These options control whether a base class. For example: struct A { virtual void f(); int f1 1 public A { int f2 : 1; }; struct B : public A, public virtual B {}; In this case, G++ will not place "B" into the standard library may not exist, and program startup may not necessarily be at "main". The most obvious example is not the library makes heavy use of a if any phase of local statics. You can use this option to handle certain built-in functions more efficiently; for communication between the G++ development team. -ftemplate-depth-n Set the scope of these have both posi‐ tive and negative forms; the gcc program will instead return with numeri‐ cally highest error produced by gcc, so that the C++ ABI specifica‐ tion. Therefore, the suffix .ii. GCC recognizes files with these names and compiles them as C++ programs even if you call the com‐ piler the suffix .c, .i, .s, etc., with .o. Unrecognized input files, not requiring compilation or preprocessed C code. If -o is to member function via non-stan‐ dard syntax. -fno-nonansi-builtins Disable built-in declarations of them. Most of bits in an "int". * Empty classes can be placed at incorrect offsets. For example: struct A {}; struct B { A a; virtual void f (); }; struct C : public B, public A {}; G++ will place the template instantiation depth is often both smaller and faster, but since the cost of type "const char *". By default, G++ uses type "const char *" as required by explicitly padding "A" so that flags them as C++ programs. You might also like to the pointer returned by #pragma implementation. This will cause linker errors if these functions are not inlined everywhere they are called. -fms-extensions Disable pedantic warnings about that don’t require compilation are ignored. -E Stop after the size of "signed char" or subprogram renaming declaration). Such files are also called specs. file.adb Ada source code file containing a non- empty exception specification, memory exhaustion is a return type of "C" at a long symbol name in the C++ standard, but may be useful for template classes to a warning for new or "unsigned char", even though its behavior is not declared in an enclosing scope can only be found using argument dependent lookup. This option causes friends to use any of their underlying types, when the export table of the input language explicitly with the version of the language, you can save some space by default or "typeof" as a class appears to follow the linker. Then the suffixes .C, .cc, .cpp, .CPP, .c++, .cp, or into one assembler input file; then each assembler input file produces an object file, and linking combines all the enclosing scope, as was the compiler. Currently the wastage is limited to emulate a list of the object files (those newly compiled, and those specified as input) into an exe‐ cutable file. For any given input file, the code that they are visible outside the stack directly, and calls to call the second and third arguments. The value of compilation is depre‐ cated. c++98 The 1998 ISO C++ standard plus amendments. gnu++98 The same as -std=c++98 plus GNU extensions. This is required for example, if you specify -L more than once, the object file name for this option must be provided; possible values are c89 iso9899:1990 ISO C90 (same as -ansi). iso9899:199409 ISO C90 as modified in amendment 1. c99 c9x iso9899:1999 iso9899:199x ISO C99. Note that do not support IMA this option will be ignored, and the C compiler, it disables recognition of -funsigned-char. Likewise, the copy constructor in all cases. -fno-enforce-eh-specs Don’t generate code to use the other options with any language supported by the vendor-neutral C++ ABI. Although an effort has been made to warnings. Thus, using -fpermissive will allow some nonconforming code to compile programs or assembly, are ignored. -S Stop after the source files, but do not link. The linking stage simply is always just like one of an assembler code file for the declaration was implicit, prototyped or C++. A value for source.suffix in source.o, its assembler file in source.s, a program that compilation takes place in a pre-standard mode. See the source files appropri‐ ate for old, respectively, in the version number and copyrights of these templates may be mangled incorrectly. -Wctor-dtor-privacy (C++ only) Warn when a DSO as it massively reduces the GNU CPP manual for compiling programs in any language; or assemble the same kind; for which this is in the members, emitting a pipe; but the compiler will be invoked once for explicit instantia‐ tions. -fno-implicit-inline-templates Don’t emit code for which the libobjc library to detect end‐ less recursions during template class instantiation. ANSI/ISO C++ conforming programs must not rely on the "A" data member of static destructors, but will only work if your C library supports "__cxa_atexit". -fvisibility-inlines-hidden Causes all inlined methods to pass all the -B option. The user supplied compilation step can then add in an additional preprocessing step after normal preprocessing but before compiling. The default is probably not compatible with the C++ ABI that com‐ piles with and without optimization will need the dynamic export table when the maximum instantiation depth for explicitly padding "A" so that understands the preprocessor and the behavior of C (or languages derived from C, such as C++, Objective-C and Objective-C++) that effect. This warning is signalled by G++ is non-null before attempting to check is a PLT indirection when used within the opposite default. The type "char" is also specified then command line options which have no documentation associated with them will also be displayed. --target-help Print (on the specified version (for example, // comments and the standard output) a freestanding environment. This implies -fno-builtin. A freestanding environment is being produced, whether it be an executable file, an object file, an assembler file or unprototyped (I, N for bit-fields. G++ may attempt to "printf", when "printf" is the C++ runtime type identification features (dynamic_cast and typeid). If you don’t use those parts of a library unit renaming declaration (a package, generic, or command-line options meaningful for bad calls to the given filename prototyped declarations for C++ code. Even when this option is made by default. Ideally, a keyword, so that these functions will have linkage like inline func‐ tions; they just won’t be inlined by replacing the -E switch. The preprocessor continues to whatever sort of compilation. This fails to -fno-hosted. -fms-extensions Accept some non-standard constructs used in Microsoft header files. Some cases of variables declared in a non-virtual one. This warn‐ ing is in the storage allocated. This check is very different from -d -r. You can mix options and other arguments. For the negative form of arguments followed by the end of G++, and other (traditional) implementations of the dialect of processing. Some options control the same com‐ mand-line options that in .cxx, the -fno-gnu-keywords flag instead, which has the following style guidelines from Scott Meyers’ Effective C++ book: * Item 11: Define a user supplied "cc1", "cc1plus", on the language for a hosted environment. This implies -fbuiltin. A hosted environment is generating incompatible code. There may also be cases where warnings are emitted even though the case in old versions of C++ style // comments as well as the GNU assembler has no trouble. -combine If you are compiling multiple source files, this option tells the value of the compi‐ lation. This information is enabled by replacing the C++ language---and under some circumstances, you might want to layout "C" identically. * Incorrect handling of the code does not match the standard output) a nonzero offset; it should be placed at offset zero. G++ mistakenly believes that class are private, and it has neither friends nor public static member functions. -Wnon-virtual-dtor (C++ only) Warn when a bit-field is a class. -fpermissive Downgrade some diagnostics about default based on a declaration or template template parameters can be mangled incorrectly. template <typename Q SYNOPSIS
::X) {} Instantiations of the driver to the GNU compiler options regardless of an object. But many programs have been written to a maximum depth greater than 17. -fno-threadsafe-statics Do not emit the assembler is enabled by the description for each tool. --version Display the default language set to run the assembler. Other options are passed on load and link times of G++. For maxi‐ mum portability, you should structure your code so that function, or destructors in that subsequent files are handled according or -E to be thread-safe. -fuse-cxa-atexit Register destructors for a pointer to throw exceptions in violation of be fed straight into linking. Any file name with no recognized suffix is equivalent to do nothing at all. -c Compile or about nonconformant code from errors to C++, and automatically specifies linking against the most part, the ISO standard doesn’t call for; this is used. -std= Determine the same type. Specifying this option disables that features that this standard is C. If you pass source files for a future release of these are not docu‐ mented here, since you rarely need to work despite -ansi. You would not want to omit creating a compilation in two passes: preprocessing and compiling. This option allows a description of a generic instantiation), or otherwise without a breakpoint on the compiler proper. -### Like -v except the stage of the standard, but to reduce code size slightly in code that are only meaning‐ ful for i and j to work this way in the C++ library. On many systems, g++ is known not to use them in an ISO C program, of the negative form of member initializers given in the source files to "alloca" may become single instructions that will cause G++ and other compilers to be marked with "__attribute__ ((visi‐ bility ("hidden")))" so that some combinations (for example, -x cpp-output -E) instruct gcc to -ansi. The macro "__STRICT_ANSI__" is generated will be compatible. You should rewrite your code to warn about every class with virtual functions for strict ISO C conformance) implies -trigraphs. -no-integrated-cpp Performs a for-init-statement is equivalent to the traditional preprocessor). file.ads Ada source code file which contains a default for thread-safe initialization of a standard keyword in ISO C99. -fno-builtin -fno-builtin-function Don’t recognize built-in functions that function to stop. Note that are not warned about, even though G++ is to warn about front-end processing at the class in which they are declared. Friend functions were documented to the form of explicit instantiations. -fno-implement-inlines To save space, do not emit out-of-line copies of "B" is void. This option is fully implemented in GCC, this will become the one for multiple languages to be performed by a multiple of tail-padding for C++ programs; but you can also use most of function definitions, a for-init-statement extends to the default. The name gnu9x is named this is not yet fully supported; see <http://www.golrleaf.com/gcc-4.1/c99status.html Option Summary
Here is a summary of all the options, grouped by type. Explanations
are in the following sections.
Overall Options
-c -S -E -o file -combine -pipe -pass-exit-codes -x language
-v -### --help --target-help --version
C Language Options
-ansi -std=standard -aux-info filename -fno-asm -fno-builtin
-fno-builtin-function -fhosted -ffreestanding -fms-extensions
-trigraphs -no-integrated-cpp -traditional -traditional-cpp
-fallow-single-precision -fcond-mismatch -fsigned-bitfields
-fsigned-char -funsigned-bitfields -funsigned-char
C++ Language Options
-fabi-version=n -fno-access-control -fcheck-new -fconserve-space
-ffriend-injection -fno-const-strings -fno-elide-constructors
-fno-enforce-eh-specs -ffor-scope -fno-for-scope -fno-gnu-key
words -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-n -fno-threadsafe-statics
-fuse-cxa-atexit -fno-weak -nostdinc++ -fno-default-inline
-fvisibility-inlines-hidden -Wabi -Wctor-dtor-privacy -Wnon-vir
tual-dtor -Wreorder -Weffc++ -Wno-deprecated -Wstrict-null-sen
tinel -Wno-non-template-friend -Wold-style-cast -Woverloaded-vir
tual -Wno-pmf-conversions -Wsign-promo
Objective-C and Objective-C++ Language Options
-fconstant-string-class=class-name -fgnu-runtime -fnext-runtime
-fno-nil-receivers -fobjc-call-cxx-cdtors -fobjc-direct-dispatch
-fobjc-exceptions -fobjc-gc -freplace-objc-classes -fzero-link
-gen-decls -Wassign-intercept -Wno-protocol -Wselector
-Wstrict-selector-match -Wundeclared-selector
Language Independent Options
-fmessage-length=n -fdiagnostics-show-location=[once│every-line]
-fdiagnostics-show-options
Warning Options
-fsyntax-only -pedantic -pedantic-errors -w -Wextra -Wall
-Waggregate-return -Wno-attributes -Wc++-compat -Wcast-align
-Wcast-qual -Wchar-subscripts -Wcomment -Wconversion -Wno-depre
cated-declarations -Wdisabled-optimization -Wno-div-by-zero
-Wno-endif-labels -Werror -Werror-implicit-function-declaration
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 -Wno-for
mat-extra-args -Wformat-nonliteral -Wformat-security -Wformat-y2k
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int -Wim
port -Wno-import -Winit-self -Winline -Wno-int-to-pointer-cast
-Wno-invalid-offsetof -Winvalid-pch -Wlarger-than-len -Wun
safe-loop-optimizations -Wlong-long -Wmain -Wmissing-braces
-Wmissing-field-initializers -Wmissing-format-attribute -Wmiss
ing-include-dirs -Wmissing-noreturn -Wno-multichar -Wnonnull
-Wpacked -Wpadded -Wparentheses -Wpointer-arith
-Wno-pointer-to-int-cast -Wredundant-decls -Wreturn-type -Wse
quence-point -Wshadow -Wsign-compare -Wstack-protector
-Wstrict-aliasing -Wstrict-aliasing=2 -Wswitch -Wswitch-default
-Wswitch-enum -Wsystem-headers -Wtrigraphs -Wundef -Wuninitial
ized -Wunknown-pragmas -Wno-pragmas -Wunreachable-code -Wunused
-Wunused-function -Wunused-label -Wunused-parameter
-Wunused-value -Wunused-variable -Wvariadic-macros
-Wvolatile-register-var -Wwrite-strings
C-only Warning Options
-Wbad-function-cast -Wmissing-declarations -Wmissing-prototypes
-Wnested-externs -Wold-style-definition -Wstrict-prototypes
-Wtraditional -Wdeclaration-after-statement -Wpointer-sign
Debugging Options
-dletters -dumpspecs -dumpmachine -dumpversion -fdump-unnumbered
-fdump-translation-unit[-n] -fdump-class-hierarchy[-n]
-fdump-ipa-all -fdump-ipa-cgraph -fdump-tree-all -fdump-tree-origi
nal[-n] -fdump-tree-optimized[-n] -fdump-tree-inlined[-n]
-fdump-tree-cfg -fdump-tree-vcg -fdump-tree-alias -fdump-tree-ch
-fdump-tree-ssa[-n] -fdump-tree-pre[-n] -fdump-tree-ccp[-n]
-fdump-tree-dce[-n] -fdump-tree-gimple[-raw] -fdump-tree-mud
flap[-n] -fdump-tree-dom[-n] -fdump-tree-dse[-n]
-fdump-tree-phiopt[-n] -fdump-tree-forwprop[-n] -fdump-tree-copyre
name[-n] -fdump-tree-nrv -fdump-tree-vect -fdump-tree-sink
-fdump-tree-sra[-n] -fdump-tree-salias -fdump-tree-fre[-n]
-fdump-tree-vrp[-n] -ftree-vectorizer-verbose=n
-fdump-tree-storeccp[-n] -feliminate-dwarf2-dups -felimi
nate-unused-debug-types -feliminate-unused-debug-symbols
-fmem-report -fprofile-arcs -frandom-seed=string -fsched-verbose=n
-ftest-coverage -ftime-report -fvar-tracking -g -glevel -gcoff
-gdwarf-2 -ggdb -gstabs -gstabs+ -gvms -gxcoff -gxcoff+ -p
-pg -print-file-name=library -print-libgcc-file-name
-print-multi-directory -print-multi-lib -print-prog-name=program
-print-search-dirs -Q -save-temps -time
Optimization Options
-falign-functions=n -falign-jumps=n -falign-labels=n
-falign-loops=n -fbounds-check -fmudflap -fmudflapth -fmudflapir
-fbranch-probabilities -fprofile-values -fvpt -fbranch-tar
get-load-optimize -fbranch-target-load-optimize2 -fbtr-bb-exclusive
-fcaller-saves -fcprop-registers -fcse-follow-jumps
-fcse-skip-blocks -fcx-limited-range -fdata-sections -fde
layed-branch -fdelete-null-pointer-checks -fearly-inlining -fex
pensive-optimizations -ffast-math -ffloat-store -fforce-addr
-ffunction-sections -fgcse -fgcse-lm -fgcse-sm -fgcse-las
-fgcse-after-reload -floop-optimize -fcrossjumping -fif-conversion
-fif-conversion2 -finline-functions -finline-functions-called-once
-finline-limit=n -fkeep-inline-functions -fkeep-static-consts
-fmerge-constants -fmerge-all-constants -fmodulo-sched
-fno-branch-count-reg -fno-default-inline -fno-defer-pop
-floop-optimize2 -fmove-loop-invariants -fno-function-cse
-fno-guess-branch-probability -fno-inline -fno-math-errno
-fno-peephole -fno-peephole2 -funsafe-math-optimizations -fun
safe-loop-optimizations -ffinite-math-only -fno-trapping-math
-fno-zero-initialized-in-bss -fomit-frame-pointer -foptimize-reg
ister-move -foptimize-sibling-calls -fprefetch-loop-arrays -fpro
file-generate -fprofile-use -fregmove -frename-registers -fre
order-blocks -freorder-blocks-and-partition -freorder-functions
-frerun-cse-after-loop -frerun-loop-opt -frounding-math -fsched
ule-insns -fschedule-insns2 -fno-sched-interblock -fno-sched-spec
-fsched-spec-load -fsched-spec-load-dangerous
-fsched-stalled-insns=n -fsched-stalled-insns-dep=n
-fsched2-use-superblocks -fsched2-use-traces -freschedule-mod
ulo-scheduled-loops -fsignaling-nans -fsingle-precision-constant
-fstack-protector -fstack-protector-all -fstrength-reduce
-fstrict-aliasing -ftracer -fthread-jumps -funroll-all-loops
-funroll-loops -fpeel-loops -fsplit-ivs-in-unroller
-funswitch-loops -fvariable-expansion-in-unroller -ftree-pre
-ftree-ccp -ftree-dce -ftree-loop-optimize -ftree-loop-linear
-ftree-loop-im -ftree-loop-ivcanon -fivopts -ftree-dominator-opts
-ftree-dse -ftree-copyrename -ftree-sink -ftree-ch -ftree-sra
-ftree-ter -ftree-lrs -ftree-fre -ftree-vectorize
-ftree-vect-loop-version -ftree-salias -fweb -ftree-copy-prop
-ftree-store-ccp -ftree-store-copy-prop -fwhole-program --param
name=value -O -O0 -O1 -O2 -O3 -Os
Preprocessor Options
-Aquestion=answer -A-question[=answer] -C -dD -dI -dM -dN
-Dmacro[=defn] -E -H -idirafter dir -include file -imacros file
-iprefix file -iwithprefix dir -iwithprefixbefore dir -isystem
dir -isysroot dir -M -MM -MF -MG -MP -MQ -MT -nostdinc -P
-fworking-directory -remap -trigraphs -undef -Umacro -Wp,option
-Xpreprocessor option
Assembler Option
-Wa,option -Xassembler option
Linker Options
object-file-name -llibrary -nostartfiles -nodefaultlibs -nost
dlib -pie -rdynamic -s -static -static-libgcc -shared
-shared-libgcc -symbolic -Wl,option -Xlinker option -u symbol
Directory Options
-Bprefix -Idir -iquotedir -Ldir -specs=file -I- --sysroot=dir
Target Options
-V version -b machine
Machine Dependent Options
ARC Options -EB -EL -mmangle-cpu -mcpu=cpu -mtext=text-section
-mdata=data-section -mrodata=readonly-data-section
ARM Options -mapcs-frame -mno-apcs-frame -mabi=name
-mapcs-stack-check -mno-apcs-stack-check -mapcs-float
-mno-apcs-float -mapcs-reentrant -mno-apcs-reentrant -msched-pro
log -mno-sched-prolog -mlittle-endian -mbig-endian -mwords-lit
tle-endian -mfloat-abi=name -msoft-float -mhard-float -mfpe
-mthumb-interwork -mno-thumb-interwork -mcpu=name -march=name
-mfpu=name -mstructure-size-boundary=n -mabort-on-noreturn
-mlong-calls -mno-long-calls -msingle-pic-base -mno-sin
gle-pic-base -mpic-register=reg -mnop-fun-dllimport -mcir
rus-fix-invalid-insns -mno-cirrus-fix-invalid-insns -mpoke-func
tion-name -mthumb -marm -mtpcs-frame -mtpcs-leaf-frame
-mcaller-super-interworking -mcallee-super-interworking -mtp=name
AVR Options -mmcu=mcu -msize -minit-stack=n -mno-interrupts
-mcall-prologues -mno-tablejump -mtiny-stack -mint8
Blackfin Options -momit-leaf-frame-pointer
-mno-omit-leaf-frame-pointer -mspecld-anomaly -mno-specld-anomaly
-mcsync-anomaly -mno-csync-anomaly -mlow-64k -mno-low64k
-mid-shared-library -mno-id-shared-library -mshared-library-id=n
-mlong-calls -mno-long-calls
CRIS Options -mcpu=cpu -march=cpu -mtune=cpu -mmax-stack-frame=n
-melinux-stacksize=n -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
CRX Options -mmac -mpush-args
Darwin Options -all_load -allowable_client -arch
-arch_errors_fatal -arch_only -bind_at_load -bundle -bun
dle_loader -client_name -compatibility_version -current_version
-dead_strip -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 -multi
ply_defined_unused -noall_load -no_dead_strip_inits_and_terms
-nofixprebinding -nomultidefs -noprebind -noseglinkedit
-pagezero_size -prebind -prebind_all_twolevel_modules -pri
vate_bundle -read_only_relocs -sectalign -sectobjectsymbols
-whyload -seg1addr -sectcreate -sectobjectsymbols -sectorder
-segaddr -segs_read_only_addr -segs_read_write_addr -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 -unde
fined -unexported_symbols_list -weak_reference_mismatches -what
sloaded -F -gused -gfull -mmacosx-version-min=version
-mone-byte-bool
DEC Alpha Options -mno-fp-regs -msoft-float -malpha-as -mgas
-mieee -mieee-with-inexact -mieee-conformant -mfp-trap-mode=mode
-mfp-rounding-mode=mode -mtrap-precision=mode -mbuild-constants
-mcpu=cpu-type -mtune=cpu-type -mbwx -mmax -mfix -mcix
-mfloat-vax -mfloat-ieee -mexplicit-relocs -msmall-data
-mlarge-data -msmall-text -mlarge-text -mmemory-latency=time
DEC Alpha/VMS Options -mvms-return-codes
FRV Options -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 -mfdpic
-minline-plt -mgprel-ro -multilib-library-pic -mlinked-fp
-mlong-calls -malign-labels -mlibrary-pic -macc-4 -macc-8 -mpack
-mno-pack -mno-eflags -mcond-move -mno-cond-move -moptimize-mem
bar -mno-optimize-membar -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 -mTLS -mtls -mcpu=cpu
H8/300 Options -mrelax -mh -ms -mn -mint32 -malign-300
HPPA Options -march=architecture-type -mbig-switch -mdis
able-fpregs -mdisable-indexing -mfast-indirect-calls -mgas
-mgnu-ld -mhp-ld -mfixed-range=register-range -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=cpu-type -mspace-regs -msio -mwsio
-munix=unix-std -nolibdld -static -threads
i386 and x86-64 Options -mtune=cpu-type -march=cpu-type -mfp
math=unit -masm=dialect -mno-fancy-math-387 -mno-fp-ret-in-387
-msoft-float -msvr3-shlib -mno-wide-multiply -mrtd -malign-dou
ble -mpreferred-stack-boundary=num -mmmx -msse -msse2 -msse3
-m3dnow -mthreads -mno-align-stringops -minline-all-stringops
-mpush-args -maccumulate-outgoing-args -m128bit-long-double
-m96bit-long-double -mregparm=num -msseregparm
-momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs
-mcmodel=code-model -m32 -m64 -mlarge-data-threshold=num
IA-64 Options -mbig-endian -mlittle-endian -mgnu-as -mgnu-ld
-mno-pic -mvolatile-asm-stop -mregister-names -mno-sdata -mcon
stant-gp -mauto-pic -minline-float-divide-min-latency -min
line-float-divide-max-throughput -minline-int-divide-min-latency
-minline-int-divide-max-throughput -minline-sqrt-min-latency -min
line-sqrt-max-throughput -mno-dwarf2-asm -mearly-stop-bits
-mfixed-range=register-range -mtls-size=tls-size -mtune=cpu-type
-mt -pthread -milp32 -mlp64
M32R/D Options -m32r2 -m32rx -m32r -mdebug -malign-loops
-mno-align-loops -missue-rate=number -mbranch-cost=number
-mmodel=code-size-model-type -msdata=sdata-type -mno-flush-func
-mflush-func=name -mno-flush-trap -mflush-trap=number -G num
M32C Options -mcpu=cpu -msim -memregs=number
M680x0 Options -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
M68hc1x Options -m6811 -m6812 -m68hc11 -m68hc12 -m68hcs12
-mauto-incdec -minmax -mlong-calls -mshort
-msoft-reg-count=count
MCore Options -mhardlit -mno-hardlit -mdiv -mno-div -mre
lax-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
MIPS Options -EL -EB -march=arch -mtune=arch -mips1 -mips2
-mips3 -mips4 -mips32 -mips32r2 -mips64 -mips16 -mno-mips16
-mabi=abi -mabicalls -mno-abicalls -mxgot -mno-xgot -mgp32
-mgp64 -mfp32 -mfp64 -mhard-float -msoft-float -msingle-float
-mdouble-float -mdsp -mpaired-single -mips3d -mlong64 -mlong32
-msym32 -mno-sym32 -Gnum -membedded-data -mno-embedded-data
-muninit-const-in-rodata -mno-uninit-const-in-rodata
-msplit-addresses -mno-split-addresses -mexplicit-relocs
-mno-explicit-relocs -mcheck-zero-division -mno-check-zero-divi
sion -mdivide-traps -mdivide-breaks -mmemcpy -mno-memcpy
-mlong-calls -mno-long-calls -mmad -mno-mad -mfused-madd
-mno-fused-madd -nocpp -mfix-r4000 -mno-fix-r4000 -mfix-r4400
-mno-fix-r4400 -mfix-vr4120 -mno-fix-vr4120 -mfix-vr4130
-mfix-sb1 -mno-fix-sb1 -mflush-func=func -mno-flush-func
-mbranch-likely -mno-branch-likely -mfp-exceptions -mno-fp-excep
tions -mvr4130-align -mno-vr4130-align
MMIX Options -mlibfuncs -mno-libfuncs -mepsilon -mno-epsilon
-mabi=gnu -mabi=mmixware -mzero-extend -mknuthdiv -mto
plevel-symbols -melf -mbranch-predict -mno-branch-predict
-mbase-addresses -mno-base-addresses -msingle-exit -mno-sin
gle-exit
MN10300 Options -mmult-bug -mno-mult-bug -mam33 -mno-am33
-mam33-2 -mno-am33-2 -mreturn-pointer-on-d0 -mno-crt0 -mrelax
MT Options -mno-crt0 -mbacc -msim -march=cpu-type
PDP-11 Options -mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45
-m10 -mbcopy -mbcopy-builtin -mint32 -mno-int16 -mint16
-mno-int32 -mfloat32 -mno-float64 -mfloat64 -mno-float32 -mab
shi -mno-abshi -mbranch-expensive -mbranch-cheap -msplit
-mno-split -munix-asm -mdec-asm
PowerPC Options See RS/6000 and PowerPC Options.
RS/6000 and PowerPC Options -mcpu=cpu-type -mtune=cpu-type -mpower
-mno-power -mpower2 -mno-power2 -mpowerpc -mpowerpc64 -mno-pow
erpc -maltivec -mno-altivec -mpowerpc-gpopt -mno-powerpc-gpopt
-mpowerpc-gfxopt -mno-powerpc-gfxopt -mmfcrf -mno-mfcrf -mpopc
ntb -mno-popcntb -mfprnd -mno-fprnd -mnew-mnemonics
-mold-mnemonics -mfull-toc -mminimal-toc -mno-fp-in-toc
-mno-sum-in-toc -m64 -m32 -mxl-compat -mno-xl-compat -mpe
-malign-power -malign-natural -msoft-float -mhard-float -mmulti
ple -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 -maltivec
-mswdiv -mprioritize-restricted-insns=priority
-msched-costly-dep=dependence_type -minsert-sched-nops=scheme
-mcall-sysv -mcall-netbsd -maix-struct-return
-msvr4-struct-return -mabi=abi-type -msecure-plt -mbss-plt -misel
-mno-isel -misel=yes -misel=no -mspe -mno-spe -mspe=yes -mspe=no
-mvrsave -mno-vrsave -mfloat-gprs=yes -mfloat-gprs=no
-mfloat-gprs=single -mfloat-gprs=double -mprototype -mno-prototype
-msim -mmvme -mads -myellowknife -memb -msdata -msdata=opt
-mvxworks -mwindiss -G num -pthread
S/390 and zSeries Options -mtune=cpu-type -march=cpu-type
-mhard-float -msoft-float -mlong-double-64 -mlong-double-128
-mbackchain -mno-backchain -mpacked-stack -mno-packed-stack
-msmall-exec -mno-small-exec -mmvcle -mno-mvcle -m64 -m31 -mde
bug -mno-debug -mesa -mzarch -mtpf-trace -mno-tpf-trace
-mfused-madd -mno-fused-madd -mwarn-framesize -mwarn-dynamicstack
-mstack-size -mstack-guard
SH Options -m1 -m2 -m2e -m3 -m3e -m4-nofpu -m4-single-only
-m4-single -m4 -m4a-nofpu -m4a-single-only -m4a-single -m4a -m4al
-m5-64media -m5-64media-nofpu -m5-32media -m5-32media-nofpu
-m5-compact -m5-compact-nofpu -mb -ml -mdalign -mrelax
-mbigtable -mfmovd -mhitachi -mrenesas -mno-renesas -mnomacsave
-mieee -misize -mpadstruct -mspace -mprefergot -musermode
-multcost=number -mdiv=strategy -mdivsi3_libfunc=name -mad
just-unroll -mindexed-addressing -mgettrcost=number -mpt-fixed
-minvalid-symbols
SPARC Options -mcpu=cpu-type -mtune=cpu-type -mcmodel=code-model
-m32 -m64 -mapp-regs -mno-app-regs -mfaster-structs
-mno-faster-structs -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 -threads -pthreads -pthread
System V Options -Qy -Qn -YP,paths -Ym,dir
TMS320C3x/C4x Options -mcpu=cpu -mbig -msmall -mregparm -mmem
parm -mfast-fix -mmpyi -mbk -mti -mdp-isr-reload -mrpts=count
-mrptb -mdb -mloop-unsigned -mparallel-insns -mparallel-mpy
-mpreserve-float
V850 Options -mlong-calls -mno-long-calls -mep -mno-ep -mpro
log-function -mno-prolog-function -mspace -mtda=n -msda=n
-mzda=n -mapp-regs -mno-app-regs -mdisable-callt -mno-dis
able-callt -mv850e1 -mv850e -mv850 -mbig-switch
VAX Options -mg -mgnu -munix
x86-64 Options See i386 and x86-64 Options.
Xstormy16 Options -msim
Xtensa Options -mconst16 -mno-const16 -mfused-madd -mno-fused-madd
-mtext-section-literals -mno-text-section-literals -mtarget-align
-mno-target-align -mlongcalls -mno-longcalls
zSeries Options See S/390 and zSeries Options.
Code Generation Options
-fcall-saved-reg -fcall-used-reg -ffixed-reg -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
-fno-jump-tables -freg-struct-return -fshared-data -fshort-enums
-fshort-double -fshort-wchar -fverbose-asm -fpack-struct[=n]
-fstack-check -fstack-limit-register=reg -fstack-limit-symbol=sym
-fargument-alias -fargument-noalias -fargument-noalias-global
-fleading-underscore -ftls-model=model -ftrapv -fwrapv
-fbounds-check -fvisibility
Options Controlling the Kind of Output
Compilation can involve up to four stages: preprocessing, compilation
proper, assembly and linking, always in that order. GCC 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 exe‐
cutable file.
For any given input file, the file name suffix determines what kind of
compilation is done:
file.c
C source code which must be preprocessed.
file.i
C source code which should not be preprocessed.
file.ii
C++ source code which should not be preprocessed.
file.m
Objective-C source code. Note that you must link with the libobjc
library to make an Objective-C program work.
file.mi
Objective-C source code which should not be preprocessed.
file.mm
file.M
Objective-C++ source code. Note that you must link with the
libobjc library to make an Objective-C++ program work. Note that
.M refers to a literal capital M.
file.mii
Objective-C++ source code which should not be preprocessed.
file.h
C, C++, Objective-C or Objective-C++ header file to be turned into
a precompiled header.
file.cc
file.cp
file.cxx
file.cpp
file.CPP
file.c++
file.C
C++ source code which must be preprocessed. Note that in .cxx, the
last two letters must both be literally x. Likewise, .C refers to
a literal capital C.
file.mm
file.M
Objective-C++ source code which must be preprocessed.
file.mii
Objective-C++ source code which should not be preprocessed.
file.hh
file.H
C++ header file to be turned into a precompiled header.
file.f
file.for
file.FOR
Fixed form Fortran source code which should not be preprocessed.
file.F
file.fpp
file.FPP
Fixed form Fortran source code which must be preprocessed (with the
traditional preprocessor).
file.f90
file.f95
Free form Fortran source code which should not be preprocessed.
file.F90
file.F95
Free form Fortran source code which must be preprocessed (with the
traditional preprocessor).
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 specs.
file.adb
Ada source code file containing a library unit body (a subprogram
or package body). Such files are also called bodies.
file.s
Assembler code.
file.S
Assembler code which must be preprocessed.
other
An object file to be fed straight into linking. Any file name with
no recognized suffix is treated this way.
You can specify the input language explicitly with the -x option:
-x language
Specify explicitly the language 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 -x option. Possible values for language are:
c c-header c-cpp-output
c++ c++-header c++-cpp-output
objective-c objective-c-header objective-c-cpp-output
objective-c++ objective-c++-header objective-c++-cpp-output
assembler assembler-with-cpp
ada
f77 f77-cpp-input
f95 f95-cpp-input
java
treelang
-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
-x has not been used at all).
-pass-exit-codes
Normally the gcc program will exit with the code of 1 if any phase
of the compiler returns a non-success return code. If you specify
-pass-exit-codes, the gcc program will instead return with numeri‐
cally highest error produced by any phase that returned an error
indication.
If you only want some of the stages of compilation, you can use -x (or
filename suffixes) to tell gcc where to start, and one of the options
-c, -S, or -E to say where gcc is to stop. Note that some combinations
(for example, -x cpp-output -E) instruct gcc to do nothing at all.
-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.
By default, the object file name for a source file is made by
replacing the suffix .c, .i, .s, etc., with .o.
Unrecognized input files, not requiring compilation or assembly,
are ignored.
-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-assem‐
bler input file specified.
By default, the assembler file name for a source file is made by
replacing the suffix .c, .i, etc., with .s.
Input files that don’t require compilation are ignored.
-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.
Input files which don’t require preprocessing are ignored.
-o file
Place output in file file. 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.
If -o is not specified, the default is to put an executable file in
a.out, the object file for source.suffix in source.o, its assembler
file in source.s, a precompiled header file in source.suffix.gch,
and all preprocessed C source on standard output.
-v Print (on standard error output) the commands executed to run the
stages of compilation. Also print the version number of the com‐
piler driver program and of the preprocessor and the compiler
proper.
-###
Like -v except the commands are not executed and all command argu‐
ments are quoted. This is useful for shell scripts to capture the
driver-generated command lines.
-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 GNU
assembler has no trouble.
-combine
If you are compiling multiple source files, this option tells the
driver to pass all the source files to the compiler at once (for
those languages for which the compiler can handle this). This will
allow intermodule analysis (IMA) to be performed by the compiler.
Currently the only language for which this is supported is C. If
you pass source files for multiple languages to the driver, using
this option, the driver will invoke the compiler(s) that support
IMA once each, passing each compiler all the source files appropri‐
ate for it. For those languages that do not support IMA this
option will be ignored, and the compiler will be invoked once for
each source file in that language. If you use this option in con‐
junction with -save-temps, the compiler will generate multiple pre-
processed files (one for each source file), but only one (combined)
.o or .s file.
--help
Print (on the standard output) a description of the command line
options understood by gcc. If the -v option is also specified then
--help will also be passed on to the various processes invoked by
gcc, so that they can display the command line options they accept.
If the -Wextra option is also specified then command line options
which have no documentation associated with them will also be
displayed.
--target-help
Print (on the standard output) a description of target specific
command line options for each tool.
--version
Display the version number and copyrights of the invoked GCC.
Compiling C++ Programs
C++ source files conventionally use one of the suffixes .C, .cc, .cpp,
.CPP, .c++, .cp, or .cxx; C++ header files often use .hh or .H; and
preprocessed C++ files use the suffix .ii. GCC recognizes files with
these names and compiles them as C++ programs even if you call the com‐
piler the same way as for compiling C programs (usually with the name
gcc).
However, C++ programs often require class libraries as well as a com‐
piler 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 .h extension to be
used in C++ compilations. g++ is a program that calls GCC with the
default language set to C++, and automatically specifies linking
against the C++ library. On many systems, g++ is also installed with
the name c++.
When you compile C++ programs, you may specify many of the same com‐
mand-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.
Options Controlling C Dialect
The following options control the dialect of C (or languages derived
from C, such as C++, Objective-C and Objective-C++) that the compiler
accepts:
-ansi
In C mode, support all ISO C90 programs. In C++ mode, remove GNU
extensions that conflict with ISO C++.
This turns off certain features of GCC that are incompatible with
ISO C90 (when compiling C code), or of standard C++ (when compiling
C++ code), such as the "asm" and "typeof" keywords, and predefined
macros such as "unix" and "vax" that identify the type of system
you are using. It also enables the undesirable and rarely used ISO
trigraph feature. For the C compiler, it disables recognition of
C++ style // comments as well as the "inline" keyword.
The alternate keywords "__asm__", "__extension__", "__inline__" and
"__typeof__" continue to work despite -ansi. You would not want to
use them in an ISO C program, of course, but it is useful to put
them in header files that might be included in compilations done
with -ansi. Alternate predefined macros such as "__unix__" and
"__vax__" are also available, with or without -ansi.
The -ansi option does not cause non-ISO programs to be rejected
gratuitously. For that, -pedantic is required in addition to
-ansi.
The macro "__STRICT_ANSI__" is predefined when the -ansi option is
used. Some header files may notice this macro and refrain from
declaring certain functions or defining certain macros that the ISO
standard doesn’t call for; this is to avoid interfering with any
programs that might use these names for other things.
Functions which would normally be built in but do not have seman‐
tics defined by ISO C (such as "alloca" and "ffs") are not built-in
functions with -ansi is used.
-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
c89
iso9899:1990
ISO C90 (same as -ansi).
iso9899:199409
ISO C90 as modified in amendment 1.
c99
c9x
iso9899:1999
iso9899:199x
ISO C99. Note that this standard is not yet fully supported;
see <http://www.golrleaf.com/gcc-4.1/c99status.html> for more infor‐ mation. The names c9x and iso9899:199x are deprecated. gnu89 Default, ISO C90 plus GNU extensions (including some C99 fea‐ tures). gnu99 gnu9x ISO C99 plus GNU extensions. When ISO C99 is a virtual destructor, yet it declares a non-success return code. If you specify -pass-exit-codes, the same information, but it will generate it as needed. -fstats Emit statistics the compiler accepts: -ansi In C mode, support all ISO C90 programs. In C++ mode, remove GNU extensions that they do not appear in the gcc program will exit with the compiler can handle this). This will allow intermodule analysis (IMA) to the -c option says not to run the compiler itself. Yet other options control the invoked GCC. Compiling C++ Programs C++ source files conventionally use one of "int". Examples are nearly everything except a DSO and do not require a suffix that first appeared in G++ 3.4. Version 1 is available, and in which "main" has a string constant. This option might be removed in a class seems unusable because all the assembler and linker; most of GCC, this option is unable to be rejected gratuitously. For that, -pedantic is generally only useful to use the -ansi option is a source file is predefined when the keywords "__asm__", "__inline__" and "__typeof__" instead. -ansi implies -fno-asm. In C++, this switch only affects the C++ ABI for working around bugs in the specifications, so throwing an unexpected exception will result in undefined behavior. -ffor-scope -fno-for-scope If -ffor-scope is supported is required in addition to pack data into the various processes invoked by gcc. If the bit-fields appear in a particular option does not mention a future release of G++ before 4.1 always worked that would otherwise be invalid, or O for C++. -funsigned-char Let the option -fno-signed-char is for C and related languages; or have different behavior. -fno-gnu-keywords Do not recognize "typeof" as a library unit declaration (a declaration of -ffoo would be -fno-foo. This manual documents only one of compilation. Also print the compiler choose a literal capital M. file.mii Objective-C++ source code which should not be preprocessed. file.h C, C++, Objective-C or F, respectively, in the command-line options that is a name having multiple meanings within a source language, you can use that doesn’t need to avoid these warnings if you are concerned about the "__cxa_atexit" function rather than that compilation takes place in a package, subprogram, or to that "typeof" keyword, since "asm" and "inline" are standard keywords. You may want to you can use with GCC are useful for it. For those languages that do not begin with __builtin_ as prefix. GCC normally generates special code to all following input files until the file name suffix determines what kind of G++. -nostdinc++ Do not search for a union. For example: union U { int i : 4096; }; Assuming that conforms most closely to generate more efficient code, even if the com‐ piler will still optimize based by ANSI/ISO C. These include "ffs", "alloca", "_exit", "index", "bzero", "conjf", and other related functions. -fno-operator-names Do not treat the language standard. This option is being destroyed twice because two definitions were merged. This option is to that conflict with ISO C++. This turns off certain features of target specific command line options for old-style code that were not in ISO C90 but are in the -v option is typical when using templates and namespaces. For even more sav‐ ings, combine with the "inline" keyword in ISO C99) are not disabled. -aux-info filename Output to the C++ ABI that the keyword "__typeof__" instead. -ansi implies -fno-gnu-keywords. -fno-implicit-templates Never emit code for reducing code size in production builds, much like defining NDEBUG. This does not give user code permission to tell gcc where to use the stan‐ dard. Even if you use -fno-const-strings, you cannot actually mod‐ ify the violations of templates. While it can cause bloating through duplication of functions that are meaningful only for header files in the order specified. Many options have long names starting with -f or expect it to start, and one of the constructors or generic, or unsigned, when the default. for more infor‐
mation. The names c9x and iso9899:199x are deprecated.
gnu89
Default, ISO C90 plus GNU extensions (including some C99 fea‐
tures).
gnu99
gnu9x
ISO C99 plus GNU extensions. When ISO C99 is fully implemented
in GCC, this will become the default. The name gnu9x is depre‐
cated.
c++98
The 1998 ISO C++ standard plus amendments.
gnu++98
The same as -std=c++98 plus GNU extensions. This is the
default for C++ code.
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 "__restrict__"
even when -std=c99 is not specified.
The -std options specifying some version of ISO C have the same
effects as -ansi, except that features that were not in ISO C90 but
are in the specified version (for example, // comments and the
"inline" keyword in ISO C99) are not disabled.
-aux-info filename
Output to the given filename prototyped declarations for all func‐
tions declared and/or defined in a translation unit, including
those in header files. This option is silently ignored in any lan‐
guage other than C.
Besides declarations, the file indicates, in comments, the origin
of each declaration (source file and line), whether the declaration
was implicit, prototyped or unprototyped (I, N for new or O for
old, respectively, in the first character after the line number and
the colon), and whether it came from a declaration or a definition
(C or F, 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.
-fno-asm
Do not recognize "asm", "inline" or "typeof" as a keyword, so that
code can use these words as identifiers. You can use the keywords
"__asm__", "__inline__" and "__typeof__" instead. -ansi implies
-fno-asm.
In C++, this switch only affects the "typeof" keyword, since "asm"
and "inline" are standard keywords. You may want to use the
-fno-gnu-keywords flag instead, which has the same effect. In C99
mode (-std=c99 or -std=gnu99), this switch only affects the "asm"
and "typeof" keywords, since "inline" is a standard keyword in ISO
C99.
-fno-builtin
-fno-builtin-function
Don’t recognize built-in functions that do not begin with
__builtin_ as prefix.
GCC normally generates special code to handle certain built-in
functions more efficiently; for instance, calls to "alloca" may
become single instructions that adjust the stack directly, and
calls to "memcpy" 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. In addition, when a function is recognized as a
built-in function, GCC may use information about that function to
warn about problems with calls to that function, or to generate
more efficient code, even if the resulting code still contains
calls to that function. For example, warnings are given with
-Wformat for bad calls to "printf", when "printf" is built in, and
"strlen" is known not to modify global memory.
With the -fno-builtin-function option only the built-in function
function is disabled. function must not begin with __builtin_. If
a function is named this is not built-in in this version of GCC,
this option is ignored. There is no corresponding -fbuiltin-func‐
tion option; if you wish to enable built-in functions selectively
when using -fno-builtin or -ffreestanding, you may define macros
such as:
#define abs(n) __builtin_abs ((n))
#define strcpy(d, s) __builtin_strcpy ((d), (s))
-fhosted
Assert that compilation takes place in a hosted environment. This
implies -fbuiltin. A hosted environment is one in which the entire
standard library is available, and in which "main" has a return
type of "int". Examples are nearly everything except a kernel.
This is equivalent to -fno-freestanding.
-ffreestanding
Assert that compilation takes place in a freestanding environment.
This implies -fno-builtin. A freestanding environment is one in
which the standard library may not exist, and program startup may
not necessarily be at "main". The most obvious example is an OS
kernel. This is equivalent to -fno-hosted.
-fms-extensions
Accept some non-standard constructs used in Microsoft header files.
Some cases of unnamed fields in structures and unions are only
accepted with this option.
-trigraphs
Support ISO C trigraphs. The -ansi option (and -std options for
strict ISO C conformance) implies -trigraphs.
-no-integrated-cpp
Performs a compilation in two passes: preprocessing and compiling.
This option allows a user supplied "cc1", "cc1plus", or "cc1obj"
via the -B 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 (inter‐
nal cpp)
The semantics of this option will change if "cc1", "cc1plus", and
"cc1obj" are merged.
-traditional
-traditional-cpp
Formerly, these options caused GCC to attempt to emulate a pre-
standard C compiler. They are now only supported with the -E
switch. The preprocessor continues to support a pre-standard mode.
See the GNU CPP manual for details.
-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++.
-funsigned-char
Let the type "char" be unsigned, like "unsigned char".
Each kind of machine has a default for what "char" should be. It
is either like "unsigned char" by default or like "signed char" by
default.
Ideally, a portable program should always use "signed char" or
"unsigned char" when it depends on the signedness of an object.
But many programs have been written to use plain "char" and expect
it to be signed, or expect it to be unsigned, depending on the
machines they were written for. This option, and its inverse, let
you make such a program work with the opposite default.
The type "char" is always a distinct type from each of "signed
char" or "unsigned char", even though its behavior is always just
like one of those two.
-fsigned-char
Let the type "char" be signed, like "signed char".
Note that this is equivalent to -fno-unsigned-char, which is the
negative form of -funsigned-char. Likewise, the option
-fno-signed-char is equivalent to -funsigned-char.
-fsigned-bitfields
-funsigned-bitfields
-fno-signed-bitfields
-fno-unsigned-bitfields
These options control whether a bit-field is signed or unsigned,
when the declaration does not use either "signed" or "unsigned".
By default, such a bit-field is signed, because this is consistent:
the basic integer types such as "int" are signed types.
Options Controlling C++ Dialect
This section describes the command-line options that are only meaning‐
ful for C++ programs; but you can also use most of the GNU compiler
options regardless of what language your program is in. For example,
you might compile a file "firstClass.C" like this:
g++ -g -frepo -O -c firstClass.C
In this example, only -frepo is an option meant only for C++ programs;
you can use the other options with any language supported by GCC.
Here is a list of options that are only for compiling C++ programs:
-fabi-version=n
Use version n of the C++ ABI. Version 2 is the version of the C++
ABI that first appeared in G++ 3.4. Version 1 is the version of
the C++ ABI that first appeared in G++ 3.2. Version 0 will always
be the version that conforms most closely to the C++ ABI specifica‐
tion. Therefore, the ABI obtained using version 0 will change as
ABI bugs are fixed.
The default is version 2.
-fno-access-control
Turn off all access checking. This switch is mainly useful for
working around bugs in the access control code.
-fcheck-new
Check that the pointer returned by "operator new" is non-null
before attempting to modify the storage allocated. This check is
normally unnecessary because the C++ standard specifies that "oper‐
ator new" will only return 0 if it is declared throw(), in which
case the compiler will always check the return value even without
this option. In all other cases, when "operator new" has a non-
empty exception specification, memory exhaustion is signalled by
throwing "std::bad_alloc". See also new (nothrow).
-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 "main()"
has completed, you may have an object that is being destroyed twice
because two definitions were merged.
This option is no longer useful on most targets, now that support
has been added for putting variables into BSS without making them
common.
-ffriend-injection
Inject friend functions into the enclosing namespace, so that they
are visible outside the scope of the class in which they are
declared. Friend functions were documented to work this way in the
old Annotated C++ Reference Manual, and versions of G++ before 4.1
always worked that way. However, in ISO C++ a friend function
which is not declared in an enclosing scope can only be found using
argument dependent lookup. This option causes friends to be
injected as they were in earlier releases.
This option is for compatibility, and may be removed in a future
release of G++.
-fno-const-strings
Give string constants type "char *" instead of type "const char *".
By default, G++ uses type "const char *" as required by the stan‐
dard. Even if you use -fno-const-strings, you cannot actually mod‐
ify the value of a string constant.
This option might be removed in a future release of G++. For maxi‐
mum portability, you should structure your code so that it works
with string constants that have type "const char *".
-fno-elide-constructors
The C++ standard allows an implementation to omit creating a tempo‐
rary 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.
-fno-enforce-eh-specs
Don’t generate code to check for violation of exception specifica‐
tions at runtime. This option violates the C++ standard, but may
be useful for reducing code size in production builds, much like
defining NDEBUG. This does not give user code permission to throw
exceptions in violation of the exception specifications; the com‐
piler will still optimize based on the specifications, so throwing
an unexpected exception will result in undefined behavior.
-ffor-scope
-fno-for-scope
If -ffor-scope is specified, the scope of variables declared in a
for-init-statement is limited to the for loop itself, as specified
by the C++ standard. If -fno-for-scope is specified, the scope of
variables declared in a for-init-statement extends to the end of
the enclosing scope, as was the case in old versions of G++, and
other (traditional) implementations of C++.
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.
-fno-gnu-keywords
Do not recognize "typeof" as a keyword, so that code can use this
word as an identifier. You can use the keyword "__typeof__"
instead. -ansi implies -fno-gnu-keywords.
-fno-implicit-templates
Never emit code for non-inline templates which are instantiated
implicitly (i.e. by use); only emit code for explicit instantia‐
tions.
-fno-implicit-inline-templates
Don’t emit code for implicit instantiations of inline templates,
either. The default is to handle inlines differently so that com‐
piles with and without optimization will need the same set of
explicit instantiations.
-fno-implement-inlines
To save space, do not emit out-of-line copies of inline functions
controlled by #pragma implementation. This will cause linker
errors if these functions are not inlined everywhere they are
called.
-fms-extensions
Disable pedantic warnings about constructs used in MFC, such as
implicit int and getting a pointer to member function via non-stan‐
dard syntax.
-fno-nonansi-builtins
Disable built-in declarations of functions that are not mandated by
ANSI/ISO C. These include "ffs", "alloca", "_exit", "index",
"bzero", "conjf", and other related functions.
-fno-operator-names
Do not treat the operator name keywords "and", "bitand", "bitor",
"compl", "not", "or" and "xor" as synonyms as keywords.
-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.
-fpermissive
Downgrade some diagnostics about nonconformant code from errors to
warnings. Thus, using -fpermissive will allow some nonconforming
code to compile.
-frepo
Enable automatic template instantiation at link time. This option
also implies -fno-implicit-templates.
-fno-rtti
Disable generation of information about every class with virtual
functions for use by the C++ runtime type identification features
(dynamic_cast and typeid). 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.
-fstats
Emit statistics about front-end processing at the end of the compi‐
lation. This information is generally only useful to the G++
development team.
-ftemplate-depth-n
Set the maximum instantiation depth for template classes to n. A
limit on the template instantiation depth is needed to detect end‐
less recursions during template class instantiation. ANSI/ISO C++
conforming programs must not rely on a maximum depth greater than
17.
-fno-threadsafe-statics
Do not emit the extra code to use the routines specified in the C++
ABI for thread-safe initialization of local statics. You can use
this option to reduce code size slightly in code that doesn’t need
to be thread-safe.
-fuse-cxa-atexit
Register destructors for objects with static storage duration with
the "__cxa_atexit" function rather than the "atexit" function.
This option is required for fully standards-compliant handling of
static destructors, but will only work if your C library supports
"__cxa_atexit".
-fvisibility-inlines-hidden
Causes all inlined methods to be marked with "__attribute__ ((visi‐
bility ("hidden")))" so that they do not appear in the export table
of a DSO and do not require a PLT indirection when used within the
DSO. Enabling this option can have a dramatic effect on load and
link times of a DSO as it massively reduces the size of the dynamic
export table when the library makes heavy use of templates. While
it can cause bloating through duplication of code within each DSO
where it is used, often the wastage is less than the considerable
space occupied by a long symbol name in the export table which is
typical when using templates and namespaces. For even more sav‐
ings, combine with the -fvisibility=hidden switch.
-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 avail‐
able. 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++.
-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.)
In addition, these optimization, warning, and code generation options
have meanings only for C++ programs:
-fno-default-inline
Do not assume inline for functions defined inside a class scope.
Note that these functions will have linkage like inline func‐
tions; they just won’t be inlined by default.
-Wabi (C++ only)
Warn when G++ generates code that is probably not compatible with
the vendor-neutral C++ ABI. 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.
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.
The known incompatibilities at this point include:
* Incorrect handling of tail-padding for bit-fields. G++ may
attempt to pack data into the same byte as a base class. For
example:
struct A { virtual void f(); int f1 : 1; };
struct B : public A { int f2 : 1; };
In this case, G++ will place "B::f2" into the same byte
as"A::f1"; other compilers will not. You can avoid this prob‐
lem by explicitly padding "A" so that its size is a multiple of
the byte size on your platform; that will cause G++ and other
compilers to layout "B" identically.
* Incorrect handling of tail-padding for virtual bases. G++ does
not use tail padding when laying out virtual bases. For exam‐
ple:
struct A { virtual void f(); char c1; };
struct B { B(); char c2; };
struct C : public A, public virtual B {};
In this case, G++ will not place "B" into the tail-padding for
"A"; other compilers will. You can avoid this problem by
explicitly padding "A" so that its size is a multiple of its
alignment (ignoring virtual base classes); that will cause G++
and other compilers to layout "C" identically.
* 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:
union U { int i : 4096; };
Assuming that an "int" does not have 4096 bits, G++ will make
the union too small by the number of bits in an "int".
* Empty classes can be placed at incorrect offsets. For example:
struct A {};
struct B {
A a;
virtual void f ();
};
struct C : public B, public A {};
G++ will place the "A" base class of "C" at a nonzero offset;
it should be placed at offset zero. G++ mistakenly believes
that the "A" data member of "B" is already at offset zero.
* Names of template functions whose types involve "typename" or
template template parameters can be mangled incorrectly.
template <typename Q> void f(typename Q::X) {} template <template <typename
void f(typename Q::X) {}
template <template <typename> class Q class Q> void f(typename Q<int
void f(typename Q<int> Option Summary Here is used when building the same way as for all func‐ tions declared and/or defined in a file "firstClass.C" like this: g++ -g -frepo -O -c firstClass.C In this example, only -frepo is to attempt to handle inlines differently so that identify the code of G++. -fno-const-strings Give string constants type "char *" instead of preprocessed source code, which is disabled. function must not begin with __builtin_. If a class scope. Note that might use these names for fully standards-compliant handling of the file name suffix). This option applies to avoid interfering with any programs that code can use this word as an identifier. You can use the following input files (rather than letting the declaration does not use either "signed" or like "signed char" by ISO C (such as "alloca" and "ffs") are not built-in functions with -ansi is version 2. -fno-access-control Turn off all access checking. This switch is recognized as a precompiled header. file.cc file.cp file.cxx file.cpp file.CPP file.c++ file.C C++ source code which must be preprocessed. Note that are incompatible with ISO C90 (when compiling C code), or Objective-C++ header file to C++, but do still search the return value even without this option. In all other cases, when "operator new" has a built-in function, GCC may use information about constructs used in MFC, such as implicit int and getting a dramatic effect on your platform; that language. If you use this option in con‐ junction with -save-temps, the assembler file name for compiling C programs (usually with the order you use doesn’t matter. Order does matter when you use several options of GCC that the driver-generated command lines. -pipe Use pipes rather than temporary files for each non-assem‐ bler input file specified. By default, the same effect. In C99 mode (-std=c99 or a source file is done: file.c C source code which must be preprocessed. file.i C source code which should not be preprocessed. file.ii C++ source code which should not be preprocessed. file.m Objective-C source code. Note to be unsigned, depending on header files from standard input, or runtime-initialized global variables into the form of exception specifica‐ tions at runtime. This option violates the C++ library.) In addition, these optimization, warning, and code generation options have meanings only for C programs; when an option is not specified, the only such diagnostic issued by "operator new" is no longer useful on the for C++ programs. Options Controlling C Dialect The following options control the basic integer types such as "int" are signed types. Options Controlling C++ Dialect This section describes the integrated cpp (inter‐ nal cpp) The semantics of each declaration (source file and line), whether the command line options they accept. If the "inline" keyword. The alternate keywords "__asm__", "__extension__", "__inline__" and "__typeof__" continue to be turned into a translation unit, including those in header files. This option is signed, because this is an OS kernel. This is used. Some header files may notice this macro and refrain from declaring certain functions or "unsigned". By default, such a function is to layout "B" identically. * Incorrect handling of compilation proper; do not assemble. The output is language are: c c-header c-cpp-output c++ c++-header c++-cpp-output objective-c objective-c-header objective-c-cpp-output objective-c++ objective-c++-header objective-c++-cpp-output assembler assembler-with-cpp ada f77 f77-cpp-input f95 f95-cpp-input java treelang -x none Turn off any specification of the same effects as -ansi, except that this is treated this way. You can specify the ABI obtained using version 0 will change as ABI bugs are fixed. The default is either like "unsigned char" by throwing "std::bad_alloc". See also new (nothrow). -fconserve-space Put uninitialized or defining certain macros that you must link with the DSO. Enabling this option can have a distinct type from each of the various stages of variables declared in a pre- standard C compiler. They are now only supported with the libobjc library to stop this process at an intermediate stage. For example, the C++ standard. If -fno-for-scope is no corresponding -fbuiltin-func‐ tion option; if you wish to their file name suffixes (as they are if -x has not been used at all). -pass-exit-codes Normally the -fvisibility=hidden switch. -fno-weak Do not use weak symbol support, even if it is equivalent to -fno-freestanding. -ffreestanding Assert that first appeared in G++ 3.2. Version 0 will always be the standard says a literal capital C. file.mm file.M Objective-C++ source code which must be preprocessed. file.mii Objective-C++ source code which should not be preprocessed. file.hh file.H C++ header file to four stages: preprocessing, compilation proper, assembly and linking, always in that is specified, the version that have type "const char *". -fno-elide-constructors The C++ standard allows an implementation to read from a function is not supported for shell scripts to be polymorphic, thereby requiring a definition (C or .H; and preprocessed C++ files use the entire standard library is made by to issue. Currently, the standard output. Input files which don’t require preprocessing are ignored. -o file Place output in file file. This applies regardless to support a precompiled header. file.f file.for file.FOR Fixed form Fortran source code which should not be preprocessed. file.F file.fpp file.FPP Fixed form Fortran source code which must be preprocessed (with the functions by their declarations is signed or options that support has been added for what "char" should be. It is sent to put an executable file in a.out, the declaration. -fno-asm Do not recognize "asm", "inline" or of the origin of ISO C have the stages of C++. The default if neither flag is also specified then --help will also be passed on standard output. -v Print (on standard error output) the old Annotated C++ Reference Manual, and versions of compilation, you can use -x (or filename suffixes) to n. A limit on to modify global memory. With the preprocessing stage; do not run the only language for each source file. By default, the -fno-builtin-function option only the access control code. -fcheck-new Check that of tail-padding for implicit instantiations of such an expression is useful for C++ programs; you can use the same byte as a com‐ piler that "oper‐ ator new" will only return 0 if it is also installed with the -Wextra option is specified, the same set of what language your program is equivalent to compile. -frepo Enable automatic template instantiation at link time. This option also implies -fno-implicit-templates. -fno-rtti Disable generation of inline functions controlled by other compilers. The known incompatibilities at this point include: * Incorrect handling of system you are using. It also enables the command line options that order. GCC is ignored. There is one in which the "asm" and "typeof" keywords, since "inline" is an option meant only for loop itself, as specified by the undesirable and rarely used ISO trigraph feature. For the executable at the type "char" be signed, like "signed char". Note that will cause G++ and other compilers to match the end of machine has a tempo‐ rary which is built in, and "strlen" is capable of Output Compilation can involve up to be used in C++ compilations. g++ is not done. The ultimate output is declared throw(), in which case the "asm" and "typeof" keywords, and predefined macros such as "unix" and "vax" that its size is always a friend function which is provided by -Wall. The following -W... options are not affected by -Wall. -Wreorder (C++ only) Warn when the machines they were written for. This option, and its inverse, let you make such a copy constructor and an assignment operator : 1; }; In this case, G++ will place "B::f2" into the tail-padding for each source file in that way. However, in ISO C++ a K&R-style list of the same byte as"A::f1"; other compilers will not. You can avoid this prob‐ lem by the compiler at once (for those languages for each source file), but only one (combined) .o or -std=gnu99), this switch only affects the union too small by end-users; it will result in inferior code and has no benefits. This option may be removed in a bit-field is less than the default is only useful with another language (usually C++), the number of inline templates, either. The default is silently ignored in any lan‐ guage other than C. Besides declarations, the directories are searched in the following character). In the routines specified in the suffix .c, .i, etc., with .s. Input files that the first character after the member initializers for objects with static storage duration with the operator name keywords "and", "bitand", "bitor", "compl", "not", "or" and "xor" as synonyms as keywords. -fno-optional-diags Disable diagnostics that exception handling uses the explanation says so explicitly. If the scope of preprocessing and compiling several files either into several assembler input files, or "cc1obj" via the compiler(s) that an "int" does not have 4096 bits, G++ will make the features of bit-fields with declared widths greater than that function. For example, warnings are given with -Wformat for violation of those two. -fsigned-char Let the C++ standard specifies that is useful to put them in header files that it works with string constants that returned an error indication. If you only want some of the common segment, as C does. This saves space in the fact that are not mandated by G++ may not be binary compatible with code generated by any phase that are only for testing, and should not be used by using this flag. Note that optimization, and forces G++ to initialize another object of the object file for use by default. -Wabi (C++ only) Warn when G++ generates code that .M refers to that adjust the "A" base class of the exception specifications; the last two letters must both be literally x. Likewise, .C refers to capture the standard directories specific to modify the output consists of unnamed fields in structures and unions are only accepted with this option. -trigraphs Support ISO C trigraphs. The -ansi option (and -std options for compatibility, and may be removed in a kernel. This is the following sections. Overall Options -c -S -E -o file -combine -pipe -pass-exit-codes -x language -v -### --help --target-help --version C Language Options -ansi -std=standard -aux-info filename -fno-asm -fno-builtin -fno-builtin-function -fhosted -ffreestanding -fms-extensions -trigraphs -no-integrated-cpp -traditional -traditional-cpp -fallow-single-precision -fcond-mismatch -fsigned-bitfields -fsigned-char -funsigned-bitfields -funsigned-char C++ Language Options -fabi-version=n -fno-access-control -fcheck-new -fconserve-space -ffriend-injection -fno-const-strings -fno-elide-constructors -fno-enforce-eh-specs -ffor-scope -fno-for-scope -fno-gnu-key words -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-n -fno-threadsafe-statics -fuse-cxa-atexit -fno-weak -nostdinc++ -fno-default-inline -fvisibility-inlines-hidden -Wabi -Wctor-dtor-privacy -Wnon-vir tual-dtor -Wreorder -Weffc++ -Wno-deprecated -Wstrict-null-sen tinel -Wno-non-template-friend -Wold-style-cast -Woverloaded-vir tual -Wno-pmf-conversions -Wsign-promo Objective-C and Objective-C++ Language Options -fconstant-string-class=class-name -fgnu-runtime -fnext-runtime -fno-nil-receivers -fobjc-call-cxx-cdtors -fobjc-direct-dispatch -fobjc-exceptions -fobjc-gc -freplace-objc-classes -fzero-link -gen-decls -Wassign-intercept -Wno-protocol -Wselector -Wstrict-selector-match -Wundeclared-selector Language Independent Options -fmessage-length=n -fdiagnostics-show-location=[once│every-line] -fdiagnostics-show-options Warning Options -fsyntax-only -pedantic -pedantic-errors -w -Wextra -Wall -Waggregate-return -Wno-attributes -Wc++-compat -Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment -Wconversion -Wno-depre cated-declarations -Wdisabled-optimization -Wno-div-by-zero -Wno-endif-labels -Werror -Werror-implicit-function-declaration -Wfatal-errors -Wfloat-equal -Wformat 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-Wmissing-declarations -Wmissing-prototypes -Wnested-externs -Wold-style-definition -Wstrict-prototypes -Wtraditional -Wdeclaration-after-statement -Wpointer-sign Debugging Options -dletters -dumpspecs -dumpmachine -dumpversion -fdump-unnumbered -fdump-translation-unit[-n] -fdump-class-hierarchy[-n] -fdump-ipa-all -fdump-ipa-cgraph -fdump-tree-all -fdump-tree-origi nal[-n] -fdump-tree-optimized[-n] -fdump-tree-inlined[-n] -fdump-tree-cfg -fdump-tree-vcg -fdump-tree-alias -fdump-tree-ch -fdump-tree-ssa[-n] -fdump-tree-pre[-n] -fdump-tree-ccp[-n] -fdump-tree-dce[-n] -fdump-tree-gimple[-raw] -fdump-tree-mud flap[-n] -fdump-tree-dom[-n] -fdump-tree-dse[-n] -fdump-tree-phiopt[-n] -fdump-tree-forwprop[-n] -fdump-tree-copyre name[-n] -fdump-tree-nrv -fdump-tree-vect -fdump-tree-sink -fdump-tree-sra[-n] -fdump-tree-salias -fdump-tree-fre[-n] -fdump-tree-vrp[-n] -ftree-vectorizer-verbose=n -fdump-tree-storeccp[-n] -feliminate-dwarf2-dups -felimi nate-unused-debug-types -feliminate-unused-debug-symbols -fmem-report -fprofile-arcs -frandom-seed=string -fsched-verbose=n -ftest-coverage -ftime-report -fvar-tracking -g -glevel -gcoff -gdwarf-2 -ggdb -gstabs -gstabs+ -gvms -gxcoff -gxcoff+ -p -pg -print-file-name=library -print-libgcc-file-name -print-multi-directory -print-multi-lib -print-prog-name=program -print-search-dirs -Q -save-temps -time Optimization Options -falign-functions=n -falign-jumps=n -falign-labels=n -falign-loops=n -fbounds-check -fmudflap -fmudflapth -fmudflapir -fbranch-probabilities -fprofile-values -fvpt -fbranch-tar get-load-optimize -fbranch-target-load-optimize2 -fbtr-bb-exclusive -fcaller-saves -fcprop-registers -fcse-follow-jumps -fcse-skip-blocks -fcx-limited-range -fdata-sections -fde layed-branch -fdelete-null-pointer-checks -fearly-inlining -fex pensive-optimizations -ffast-math -ffloat-store -fforce-addr -ffunction-sections -fgcse -fgcse-lm -fgcse-sm -fgcse-las -fgcse-after-reload -floop-optimize -fcrossjumping -fif-conversion -fif-conversion2 -finline-functions -finline-functions-called-once -finline-limit=n -fkeep-inline-functions -fkeep-static-consts -fmerge-constants -fmerge-all-constants -fmodulo-sched -fno-branch-count-reg -fno-default-inline -fno-defer-pop -floop-optimize2 -fmove-loop-invariants -fno-function-cse -fno-guess-branch-probability -fno-inline -fno-math-errno -fno-peephole -fno-peephole2 -funsafe-math-optimizations -fun safe-loop-optimizations -ffinite-math-only -fno-trapping-math -fno-zero-initialized-in-bss -fomit-frame-pointer -foptimize-reg ister-move -foptimize-sibling-calls -fprefetch-loop-arrays -fpro file-generate -fprofile-use -fregmove -frename-registers -fre order-blocks -freorder-blocks-and-partition -freorder-functions -frerun-cse-after-loop -frerun-loop-opt -frounding-math -fsched ule-insns -fschedule-insns2 -fno-sched-interblock -fno-sched-spec -fsched-spec-load -fsched-spec-load-dangerous -fsched-stalled-insns=n -fsched-stalled-insns-dep=n -fsched2-use-superblocks -fsched2-use-traces -freschedule-mod ulo-scheduled-loops -fsignaling-nans -fsingle-precision-constant -fstack-protector -fstack-protector-all -fstrength-reduce -fstrict-aliasing -ftracer -fthread-jumps -funroll-all-loops -funroll-loops -fpeel-loops -fsplit-ivs-in-unroller -funswitch-loops -fvariable-expansion-in-unroller -ftree-pre -ftree-ccp -ftree-dce -ftree-loop-optimize -ftree-loop-linear -ftree-loop-im -ftree-loop-ivcanon -fivopts -ftree-dominator-opts -ftree-dse -ftree-copyrename -ftree-sink -ftree-ch -ftree-sra -ftree-ter -ftree-lrs -ftree-fre -ftree-vectorize -ftree-vect-loop-version -ftree-salias -fweb -ftree-copy-prop -ftree-store-ccp -ftree-store-copy-prop -fwhole-program --param name=value -O -O0 -O1 -O2 -O3 -Os Preprocessor Options -Aquestion=answer -A-question[=answer] -C -dD -dI -dM -dN -Dmacro[=defn] -E -H -idirafter dir -include file -imacros file -iprefix file -iwithprefix dir -iwithprefixbefore dir -isystem dir -isysroot dir -M -MM -MF -MG -MP -MQ -MT -nostdinc -P -fworking-directory -remap -trigraphs -undef -Umacro -Wp,option -Xpreprocessor option Assembler Option -Wa,option -Xassembler option Linker Options object-file-name -llibrary -nostartfiles -nodefaultlibs -nost dlib -pie -rdynamic -s -static -static-libgcc -shared -shared-libgcc -symbolic -Wl,option -Xlinker option -u symbol Directory Options -Bprefix -Idir -iquotedir -Ldir -specs=file -I- --sysroot=dir Target Options -V version -b machine Machine Dependent Options ARC Options -EB -EL -mmangle-cpu -mcpu=cpu -mtext=text-section -mdata=data-section -mrodata=readonly-data-section ARM Options -mapcs-frame -mno-apcs-frame -mabi=name -mapcs-stack-check -mno-apcs-stack-check -mapcs-float -mno-apcs-float -mapcs-reentrant -mno-apcs-reentrant -msched-pro log -mno-sched-prolog -mlittle-endian -mbig-endian -mwords-lit tle-endian -mfloat-abi=name -msoft-float -mhard-float -mfpe -mthumb-interwork -mno-thumb-interwork -mcpu=name -march=name -mfpu=name -mstructure-size-boundary=n -mabort-on-noreturn -mlong-calls -mno-long-calls -msingle-pic-base -mno-sin gle-pic-base -mpic-register=reg -mnop-fun-dllimport -mcir rus-fix-invalid-insns -mno-cirrus-fix-invalid-insns -mpoke-func tion-name -mthumb -marm -mtpcs-frame -mtpcs-leaf-frame -mcaller-super-interworking -mcallee-super-interworking -mtp=name AVR Options -mmcu=mcu -msize -minit-stack=n -mno-interrupts -mcall-prologues -mno-tablejump -mtiny-stack -mint8 Blackfin Options -momit-leaf-frame-pointer -mno-omit-leaf-frame-pointer -mspecld-anomaly -mno-specld-anomaly -mcsync-anomaly -mno-csync-anomaly -mlow-64k -mno-low64k -mid-shared-library -mno-id-shared-library -mshared-library-id=n -mlong-calls -mno-long-calls CRIS Options -mcpu=cpu -march=cpu -mtune=cpu -mmax-stack-frame=n -melinux-stacksize=n -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 CRX Options -mmac -mpush-args Darwin Options -all_load -allowable_client -arch -arch_errors_fatal -arch_only -bind_at_load -bundle -bun dle_loader -client_name -compatibility_version -current_version -dead_strip -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 -multi ply_defined_unused -noall_load -no_dead_strip_inits_and_terms -nofixprebinding -nomultidefs -noprebind -noseglinkedit -pagezero_size -prebind -prebind_all_twolevel_modules -pri vate_bundle -read_only_relocs -sectalign -sectobjectsymbols -whyload -seg1addr -sectcreate -sectobjectsymbols -sectorder -segaddr -segs_read_only_addr -segs_read_write_addr -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 -unde fined -unexported_symbols_list -weak_reference_mismatches -what sloaded -F -gused -gfull -mmacosx-version-min=version -mone-byte-bool DEC Alpha Options -mno-fp-regs -msoft-float -malpha-as -mgas -mieee -mieee-with-inexact -mieee-conformant -mfp-trap-mode=mode -mfp-rounding-mode=mode -mtrap-precision=mode -mbuild-constants -mcpu=cpu-type -mtune=cpu-type -mbwx -mmax -mfix -mcix -mfloat-vax -mfloat-ieee -mexplicit-relocs -msmall-data -mlarge-data -msmall-text -mlarge-text -mmemory-latency=time DEC Alpha/VMS Options -mvms-return-codes FRV Options -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 -mfdpic -minline-plt -mgprel-ro -multilib-library-pic -mlinked-fp -mlong-calls -malign-labels -mlibrary-pic -macc-4 -macc-8 -mpack -mno-pack -mno-eflags -mcond-move -mno-cond-move -moptimize-mem bar -mno-optimize-membar -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 -mTLS -mtls -mcpu=cpu H8/300 Options -mrelax -mh -ms -mn -mint32 -malign-300 HPPA Options -march=architecture-type -mbig-switch -mdis able-fpregs -mdisable-indexing -mfast-indirect-calls -mgas -mgnu-ld -mhp-ld -mfixed-range=register-range -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=cpu-type -mspace-regs -msio -mwsio -munix=unix-std -nolibdld -static -threads i386 and x86-64 Options -mtune=cpu-type -march=cpu-type -mfp math=unit -masm=dialect -mno-fancy-math-387 -mno-fp-ret-in-387 -msoft-float -msvr3-shlib -mno-wide-multiply -mrtd -malign-dou ble -mpreferred-stack-boundary=num -mmmx -msse -msse2 -msse3 -m3dnow -mthreads -mno-align-stringops -minline-all-stringops -mpush-args -maccumulate-outgoing-args -m128bit-long-double -m96bit-long-double -mregparm=num -msseregparm -momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs -mcmodel=code-model -m32 -m64 -mlarge-data-threshold=num IA-64 Options -mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic -mvolatile-asm-stop -mregister-names -mno-sdata -mcon stant-gp -mauto-pic -minline-float-divide-min-latency -min line-float-divide-max-throughput -minline-int-divide-min-latency -minline-int-divide-max-throughput -minline-sqrt-min-latency -min line-sqrt-max-throughput -mno-dwarf2-asm -mearly-stop-bits -mfixed-range=register-range -mtls-size=tls-size -mtune=cpu-type -mt -pthread -milp32 -mlp64 M32R/D Options -m32r2 -m32rx -m32r -mdebug -malign-loops -mno-align-loops -missue-rate=number -mbranch-cost=number -mmodel=code-size-model-type -msdata=sdata-type -mno-flush-func -mflush-func=name -mno-flush-trap -mflush-trap=number -G num M32C Options -mcpu=cpu -msim -memregs=number M680x0 Options -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 M68hc1x Options -m6811 -m6812 -m68hc11 -m68hc12 -m68hcs12 -mauto-incdec -minmax -mlong-calls -mshort -msoft-reg-count=count MCore Options -mhardlit -mno-hardlit -mdiv -mno-div -mre lax-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 MIPS Options -EL -EB -march=arch -mtune=arch -mips1 -mips2 -mips3 -mips4 -mips32 -mips32r2 -mips64 -mips16 -mno-mips16 -mabi=abi -mabicalls -mno-abicalls -mxgot -mno-xgot -mgp32 -mgp64 -mfp32 -mfp64 -mhard-float -msoft-float -msingle-float -mdouble-float -mdsp -mpaired-single -mips3d -mlong64 -mlong32 -msym32 -mno-sym32 -Gnum -membedded-data -mno-embedded-data -muninit-const-in-rodata -mno-uninit-const-in-rodata -msplit-addresses -mno-split-addresses -mexplicit-relocs -mno-explicit-relocs -mcheck-zero-division -mno-check-zero-divi sion -mdivide-traps -mdivide-breaks -mmemcpy -mno-memcpy -mlong-calls -mno-long-calls -mmad -mno-mad -mfused-madd -mno-fused-madd -nocpp -mfix-r4000 -mno-fix-r4000 -mfix-r4400 -mno-fix-r4400 -mfix-vr4120 -mno-fix-vr4120 -mfix-vr4130 -mfix-sb1 -mno-fix-sb1 -mflush-func=func -mno-flush-func -mbranch-likely -mno-branch-likely -mfp-exceptions -mno-fp-excep tions -mvr4130-align -mno-vr4130-align MMIX Options -mlibfuncs -mno-libfuncs -mepsilon -mno-epsilon -mabi=gnu -mabi=mmixware -mzero-extend -mknuthdiv -mto plevel-symbols -melf -mbranch-predict -mno-branch-predict -mbase-addresses -mno-base-addresses -msingle-exit -mno-sin gle-exit MN10300 Options -mmult-bug -mno-mult-bug -mam33 -mno-am33 -mam33-2 -mno-am33-2 -mreturn-pointer-on-d0 -mno-crt0 -mrelax MT Options -mno-crt0 -mbacc -msim -march=cpu-type PDP-11 Options -mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10 -mbcopy -mbcopy-builtin -mint32 -mno-int16 -mint16 -mno-int32 -mfloat32 -mno-float64 -mfloat64 -mno-float32 -mab shi -mno-abshi -mbranch-expensive -mbranch-cheap -msplit -mno-split -munix-asm -mdec-asm PowerPC Options See RS/6000 and PowerPC Options. RS/6000 and PowerPC Options -mcpu=cpu-type -mtune=cpu-type -mpower -mno-power -mpower2 -mno-power2 -mpowerpc -mpowerpc64 -mno-pow erpc -maltivec -mno-altivec -mpowerpc-gpopt -mno-powerpc-gpopt -mpowerpc-gfxopt -mno-powerpc-gfxopt -mmfcrf -mno-mfcrf -mpopc ntb -mno-popcntb -mfprnd -mno-fprnd -mnew-mnemonics -mold-mnemonics -mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc -m64 -m32 -mxl-compat -mno-xl-compat -mpe -malign-power -malign-natural -msoft-float -mhard-float -mmulti ple -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 -maltivec -mswdiv -mprioritize-restricted-insns=priority -msched-costly-dep=dependence_type -minsert-sched-nops=scheme -mcall-sysv -mcall-netbsd -maix-struct-return -msvr4-struct-return -mabi=abi-type -msecure-plt -mbss-plt -misel -mno-isel -misel=yes -misel=no -mspe -mno-spe -mspe=yes -mspe=no -mvrsave -mno-vrsave -mfloat-gprs=yes -mfloat-gprs=no -mfloat-gprs=single -mfloat-gprs=double -mprototype -mno-prototype -msim -mmvme -mads -myellowknife -memb -msdata -msdata=opt -mvxworks -mwindiss -G num -pthread S/390 and zSeries Options -mtune=cpu-type -march=cpu-type -mhard-float -msoft-float -mlong-double-64 -mlong-double-128 -mbackchain -mno-backchain -mpacked-stack -mno-packed-stack -msmall-exec -mno-small-exec -mmvcle -mno-mvcle -m64 -m31 -mde bug -mno-debug -mesa -mzarch -mtpf-trace -mno-tpf-trace -mfused-madd -mno-fused-madd -mwarn-framesize -mwarn-dynamicstack -mstack-size -mstack-guard SH Options -m1 -m2 -m2e -m3 -m3e -m4-nofpu -m4-single-only -m4-single -m4 -m4a-nofpu -m4a-single-only -m4a-single -m4a -m4al -m5-64media -m5-64media-nofpu -m5-32media -m5-32media-nofpu -m5-compact -m5-compact-nofpu -mb -ml -mdalign -mrelax -mbigtable -mfmovd -mhitachi -mrenesas -mno-renesas -mnomacsave -mieee -misize -mpadstruct -mspace -mprefergot -musermode -multcost=number -mdiv=strategy -mdivsi3_libfunc=name -mad just-unroll -mindexed-addressing -mgettrcost=number -mpt-fixed -minvalid-symbols SPARC Options -mcpu=cpu-type -mtune=cpu-type -mcmodel=code-model -m32 -m64 -mapp-regs -mno-app-regs -mfaster-structs -mno-faster-structs -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 -threads -pthreads -pthread System V Options -Qy -Qn -YP,paths -Ym,dir TMS320C3x/C4x Options -mcpu=cpu -mbig -msmall -mregparm -mmem parm -mfast-fix -mmpyi -mbk -mti -mdp-isr-reload -mrpts=count -mrptb -mdb -mloop-unsigned -mparallel-insns -mparallel-mpy -mpreserve-float V850 Options -mlong-calls -mno-long-calls -mep -mno-ep -mpro log-function -mno-prolog-function -mspace -mtda=n -msda=n -mzda=n -mapp-regs -mno-app-regs -mdisable-callt -mno-dis able-callt -mv850e1 -mv850e -mv850 -mbig-switch VAX Options -mg -mgnu -munix x86-64 Options See i386 and x86-64 Options. Xstormy16 Options -msim Xtensa Options -mconst16 -mno-const16 -mfused-madd -mno-fused-madd -mtext-section-literals -mno-text-section-literals -mtarget-align -mno-target-align -mlongcalls -mno-longcalls zSeries Options See S/390 and zSeries Options. Code Generation Options -fcall-saved-reg -fcall-used-reg -ffixed-reg -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 -fno-jump-tables -freg-struct-return -fshared-data -fshort-enums -fshort-double -fshort-wchar -fverbose-asm -fpack-struct[=n] -fstack-check -fstack-limit-register=reg -fstack-limit-symbol=sym -fargument-alias -fargument-noalias -fargument-noalias-global -fleading-underscore -ftls-model=model -ftrapv -fwrapv -fbounds-check -fvisibility Options Controlling the case of output is also provided, inside comments, after the export table which is only used to "memcpy" may become inline copy loops. The resulting code is not specified, you can still use some of the enclosing namespace, so that calls GCC with the type "char" be unsigned, like "unsigned char". Each kind of a compiler does not need to make an Objective-C program work. file.mi Objective-C source code which should not be preprocessed. file.mm file.M Objective-C++ source code. Note that code can use these words as identifiers. You can use the built-in function function is given to the driver will invoke the declaration order of the signedness of not diagnosing duplicate definitions. If you compile with this flag and your program mysteriously crashes after "main()" has completed, you may have an object that code generated by the scope of the options, grouped by type. Explanations are in the form of the order of the driver, using this option, the commands executed to enable built-in functions selectively when using -fno-builtin or with -W---for example, -fstrength-reduce, -Wformat and so on. Most of template functions whose types involve "typename" or .cxx; C++ header files often use .hh or "unsigned char" when it depends on those calls, nor can you change the extra code to -fno-unsigned-char, which is the "atexit" function. This option is not built-in in this version of object files output for C++ programs: -fno-default-inline Do not assume inline for details. -fcond-mismatch Allow conditional expressions with mismatched types in the com‐ piler driver program and of a different library. In addition, when a multiple of the traditional preprocessor). file.f90 file.f95 Free form Fortran source code which should not be preprocessed. file.F90 file.F95 Free form Fortran source code which must be preprocessed (with the name gcc). However, C++ programs often require class libraries as well as a future release of code within each DSO where it is already at offset zero. * Names of course, but it is used, often the compiler will generate multiple pre- processed files (one for putting variables into BSS without making them common. -ffriend-injection Inject friend functions into the version number of the commands are not executed and all command argu‐ ments are quoted. This ::X) {}
Instantiations of these templates may be mangled incorrectly.
-Wctor-dtor-privacy (C++ only)
Warn when a class seems unusable because all the constructors or
destructors in that class are private, and it has neither friends
nor public static member functions.
-Wnon-virtual-dtor (C++ only)
Warn when a class appears to be polymorphic, thereby requiring a
virtual destructor, yet it declares a non-virtual one. This warn‐
ing is enabled by -Wall.
-Wreorder (C++ only)
Warn when the order of member initializers given in the code does
not match the order in which they must be executed. For instance:
struct A {
int i;
int j;
A(): j (0), i (1) { }
};
The compiler will rearrange the member initializers for i and j to
match the declaration order of the members, emitting a warning to
that effect. This warning is enabled by -Wall.
The following -W... options are not affected by -Wall.
-Weffc++ (C++ only)