-Wall enables a warning I do not want, specifically -Wunknown-pragmas. How to tell GCC to suppress these warnings after it is enabled by -Wall?
gcc -Wall -Wno-unknown-pragmas
should work.
Related
Does -Wextra also enable -Wall, and does -Wall also enable -W in GCC?
-Wextra is a replacement to the old -W flag. It enables some extra warnings which are not enabled by -Wall, and does not enable -Wall by itself - if you want both, you'll have to use -Wall -Wextra.
I am trying to compile FormCalc 9.9 on a MacOS 10.10.5.
Compilation consists in running a bash script on terminal. I redirect both stdout and sterr to a log file, but this is all the output I get:
$ ./compile
Compiling for system type MacOSX-x86-64
cp -p ./bin/MacOSX-x86-64/* MacOSX-x86-64/
gcc -O3 -fomit-frame-pointer -ffast-math -Wall -Wextra -m64 -o MacOSX-x86-64/ToForm ./FormCalc/ToForm.c
./FormCalc/ToForm.c:72:9: warning: declaration does not declare anything [-Wmissing-declarations]
__attribute__ ((fallthrough));
^
>
1 warning generated.
strip MacOSX-x86-64/ToForm
gcc -O3 -fomit-frame-pointer -ffast-math -Wall -Wextra -m64 -o MacOSX-x86-64/ToFortran ./FormCalc/ToFortran.c
strip MacOSX-x86-64/ToFortran
gcc -O3 -fomit-frame-pointer -ffast-math -Wall -Wextra -m64 -o MacOSX-x86-64/ToC ./FormCalc/ToC.c
strip MacOSX-x86-64/ToC
gcc -O3 -fomit-frame-pointer -ffast-math -Wall -Wextra -m64 -o MacOSX-x86-64/reorder ./tools/reorder.c
strip MacOSX-x86-64/reorder
looking for gcc... /usr/bin/clang
looking for g++... /usr/bin/clang++
looking for fortran... /usr/local/bin/gfortran
extracting the Fortran libraries... ok
does gfortran append underscores... error linking Fortran and C
How can I get more information about the linking error?
I am porting a project from VxWorks 5.x to 7 and the new version of the "gcc" (4.8.1) compiler is not displaying the "#warning" statements within my C code.
The following are the flags I am using and none of them appear to inhibit the warning messages:
-march=corei7 -mpopcnt -maes -mpclmul -mavx -mfsgsbase -mrdrnd -mf16c -mavx2 -mmovbe -mfma -mbmi -mbmi2 -mrdseed -madx -mprfchw -nostdlib -fno-builtin -fno-defer-pop -m64 -fno-omit-frame-pointer -mcmodel=$(CM) -mno-red-zone -fno-implicit-fp -ansi -fno-zero-initialized-in-bss -O2 -w -g -w
I even added '-Wall' and that had NO affect. If I replaced on of the '#warning's with '#error', the build fails, indicating that the code IS getting compiled.
Can anybody assist?
From the manual:
-w Inhibit all warning messages.
You have two of those in your command line.
Under GNUStep on Arch Linux, I'm running into an interesting error on a fresh install.
Using my build system I run
gcc `gnustep-config --debug-flags` [other command line args]
in order to build up the command line per the operating system's necessary flags.
This works fine under Ubuntu, but on Arch Linux I'm getting a rather random error:
/usr/include/features.h:328:4: error: #warning _FORTIFY_SOURCE requires compiling with optimization (-O) [-Werror=cpp]
Well, gnustep-config --debug-flags spits out the following:
-MMD -MP -D_FORTIFY_SOURCE=2 -DGNUSTEP -DGNUSTEP_BASE_LIBRARY=1 -DGNU_GUI_LIBRARY=1 -DGNU_RUNTIME=1 -DGNUSTEP_BASE_LIBRARY=1 -fno-strict-aliasing -pthread -fPIC -g -DDEBUG -fno-omit-frame-pointer -Wall -DGSWARN -DGSDIAGNOSE -Wno-import -march=x86-64 -mtune=generic -pipe -fstack-protector-strong --param=ssp-buffer-size=4 -fgnu-runtime -fconstant-string-class=NSConstantString -fexec-charset=UTF-8 -I. -I/home/qix/GNUstep/Library/Headers -I/usr/include -D_FORTIFY_SOURCE=2 -I/usr/include -I/usr/include -I/usr/include -I/usr/lib/libffi-3.1/include/ -I/usr/lib/libffi-3.1/include -I/usr/include/libxml2 -I/usr/include/p11-kit-1
As well, I wish not to have optimizations on my debug builds (and later on I even override GNUStep's -g parameter to -g2).
Is there a way to explicitly undefine -D_FORTIFY_SOURCE later on in the command line, after the call to gnustep-config?
For example, something like
gcc `gnustep-config --debug-flags` -U_FORTIFY_SOURCE ...
where the -U undefines the previously defined macro?
Something to mention; I have -Werror enabled on purpose, and I'd like to keep it.
For now, using sed to work around this works. It appears this is a known issue with _FORTIFY_SOURCE causing issues, and there isn't a straightforward fix.
`gnustep-config --debug-flags | sed 's/-D_FORTIFY_SOURCE=2//g'`
In a Makefile of a library I am trying to build, there are a few lines specify the options to gcc:
CFLAGS += -I$(CURDIR) -pedantic -std=c89 -O3
CFLAGS += -Wall -Wno-unused-function -Wno-long-long
CFLAGS += $(if $(DEBUG), -O0 -g)
If DEBUG exists, there will be both -O3 and -O0 -g in CFLAGS. But -O0 and -O3 cannot be used at the same time. Will the one specified later supersede the one earlier?
Thanks and regards!
From the manpage:
If you use multiple -O options, with or without level numbers, the
last such option is the one that is effective.