I have a simple project with a simple configure.ac script:
AC_INIT(...)
AM_INIT_AUTOMAKE([-Wall -Werror foreign])
AC_PROG_CC
AC_CONFIG_HEADERS([config.h])
AC_CONFIG_FILES(...)
AC_OUTPUT
using GNU Autoconf version 2.69 (OpenSUSE Linux with gcc 9.2.1), but gcc is being called with no warning flags:
gcc -DHAVE_CONFIG_H -I. -I.. -g -O2 -MT aprog.o -MD -MP -MF .deps/aprog.Tpo -c -o aprog.o aprog.c
mv ...
gcc -g -O2 -o aprog aprog.o -lgmp
In particular, I found -Wformat not working. Shouldn't -Wall include -Wformat? And shouldn't all warnings appear on the make line? If I run gcc line directly with -Wformat the warning shows in compile but it doesn't when I run autoconf, configure and make.
What I'm doing wrong?
The -Wall flag in the AM_INIT_AUTOMAKE(...) invocation refers to warnings from automake and related tools like aclocal, not to compiler warnings. You will see these warnings when you are running autoreconf.
Note that while you can also add -Werror to AM_INIT_AUTOMAKE(...) to make your autoreconf run fail on warnings, many common macros (like those shipped with gettext or libtool) will still use deprecated macros which generates a warning, so -Werror means you cannot use this standard set of tools, so -Werror is not very useful in many cases.
If you want to add compiler options, there are a third party macros (e.g. AX_CHECK_COMPILE_FLAG) which test whether the compiler recognizes a given compile option and you can then add them to some variable and use that in places. That is a different stackoverflow question, though.
Related
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.
I have inherited a powerpc project that built fine under a SUSE linux environment back around 2008. My goal is to build the same thing in Linux Mint (v 17). The target processor is a powerpc, which is set in the environment variables, I believe. During the build on Mint linux, it produces the following error:
developer#Will-test-Mint-VM ~/temp/linux.apps $ make -f Makefile.runme
make DESTDIR=`pwd`/tmp install
make[1]: Entering directory `/home/developer/temp/linux.apps'
Making install in libStreamerControl
make[2]: Entering directory `/home/developer/temp/linux.apps/libStreamerControl'
/bin/bash ../libtool --tag=CC --mode=compile gcc -DHAVE_CONFIG_H -I. -I.. -I../include -I../include -ffixed-r14 -meabi -fno-builtin -std=gnu99 -Wall -g -O2 -MT streamerControl.lo -MD -MP -MF .deps/streamerControl.Tpo -c -o streamerControl.lo streamerControl.c
libtool: compile: gcc -DHAVE_CONFIG_H -I. -I.. -I../include -I../include -ffixed-r14 -meabi -fno-builtin -std=gnu99 -Wall -g -O2 -MT streamerControl.lo -MD -MP -MF .deps/streamerControl.Tpo -c streamerControl.c -o streamerControl.o
gcc: error: unrecognized command line option '-meabi'
make[2]: *** [streamerControl.lo] Error 1
...
It is complaining about the -meabi option. I have installed/updated some packages that may be relevant (updated versions of eldk-5.6, automake, libtool, and powerpc-linux-gnu-gcc 4.8.2).
Specifically, I would like to know about the -meabi option. I didn't find a lot about it. What could be causing the compiler to not know what it is? I saw the output build from the SUSE setup, and it handled the -meabi option fine. Any suggestions?
Thanks,
Will
From your comment, it sounds like you're cross compiling here (ie., your build architecture is not the same as your host architecture). In this case, your (build) gcc won't recognise -meabi, as it's only valid for the host gcc.
So, you'll need to get your project building with the correct compiler for this to work. The method to do this will depend on the makefiles in your project. You've mentioned ARCH and CROSS_COMPILE, but these variables are specific to the Linux kernel's build system.
At a guess, your makefiles probably use some fairly standard variables to control the choice of compiler & toolchain, like CC, LD, etc. Try something like:
make -f Makefile.runme CC=powerpc-linux-gnu-gcc LD=powerpc-linux-gnu-ld
If your compile still fails, you may need to provide sources (or links to) your Makefiles.
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'`
The project that I am trying to build has default flags
CFLAGS = -Wall -g -O2
CXXFLAGS = -g -O2
I need to append a flag -w to both these variables (to remove: 'consider all warnings as errors')
I have a method to work it out, give
make 'CFLAGS=-Wall -g -O2 -w'; 'CXXFLAGS=-g -O2 -w'
OR
Run ./configure and statically modify Makefile
But I want to append my options with the existing options while running configure or make
The post
Where to add a CFLAG, such as -std=gnu99, into an autotools project
conveniently uses a macro to achieve this.
You almost have it right; why did you add the semicolon?
To do it on the configure line:
./configure CFLAGS='-g -O2 -w' CXXFLAGS='-g -O2 -w'
To do it on the make line:
make CFLAGS='-g -O2 -w' CXXFLAGS='-g -O2 -w'
However, that doesn't really remove consider all warnings as errors; that removes all warnings. So specifying both -Wall and -w doesn't make sense. If you want to keep the warnings but not have them considered errors, use the -Wall -Wno-error flags.
Alternatively, most configure scripts which enable -Werror by default also have a flag such as --disable-werror or similar. Run ./configure --help and see if there's something like that.
I am trying to run program from the Learn C Hard Way book
I need to pass the library filename 'build/liblcthw.a' as the last parameter.
For eg :
Doesnt Work on Ubuntu :
gcc -g -O2 -Wall -Wextra -Isrc -rdynamic -DNDEBUG build/liblcthw.a tests/list_tests.c -o tests/list_tests
Works on Ubuntu :
gcc -g -O2 -Wall -Wextra -Isrc -rdynamic -DNDEBUG tests/list_tests.c -o tests/list_tests build/liblcthw.a
How do I handle this in Makefile ? CFLAGS will only add it before the source filename and it doesnt work. How do I force CFALGS to add the library filename at the end of the command ?
CFLAGS are flags for the C compiler. Libraries typically go into a variable called LDLIBS. Set LDLIBS=build/liblcthw.a and see if that works.
The first invocation doesn't succeed because the order of sources and libraries in the command line is wrong. The correct order is source files, then object files, followed by static libraries followed by dynamic libraries.