On Windows, using GNUstep shell and CMake, the build fails at link-time with the following type of error :
undefined reference to objc_get_class
The executed command by CMake is the following :
/C/GNUstep/bin/gcc.exe -Wl,--enable-auto-import -shared-libgcc -fexceptions -fgnu-runtime -L/usr/home/user/GNUstep/Library/Libraries -L/GNUstep/Local/Library/Libraries -L/GNUstep/System/Library/Libraries -lgnustep-base -lobjc -lws2_32 -ladvapi32 -lcomctl32 -luser32 -lcomdlg32 -lmpr -lnetapi32 -lm -I. -Wl,--whole-archive CMakeFiles/mulle-xcode-to-cmake.dir/objects.a -Wl,--no-whole-archive -Wl,--whole-archive libmullepbx.a -Wl,--no-whole-archive -o mulle-xcode-to-cmake.exe -Wl,--out-implib,libmulle-xcode-to-cmake.dll.a -Wl,--major-image-version,0,--minor-image-version,0 @CMakeFiles/mulle-xcode-to-cmake.dir/linklibs.rsp
As we can see, gcc is called with the linked libraries appearing first (-l...), then the sources appearing after them (.a).
This leads to the libraries not being linked, as the symbols in them are not yet encountered.
Using -Wl,--no-as-needed does not fix the problem.
The following manual solution fixes the issue :
1 / Run CMake from the build directory:
i.e. mkdir build && cd build
cmake -G"MSYS Makefiles" .. -Wno-dev -DCMAKE_VERBOSE_MAKEFILE=ON
2 / Go to CMakeFiles/mulle-xcode-to-cmake.dir in the build directory
3 / Open build.make
4 / Find the last gcc call. Make sure to have .a appear before -l, something like the following :
/C/GNUstep/bin/gcc.exe -Wl,--whole-archive CMakeFiles/mulle-xcode-to-cmake.dir/objects.a -Wl,--no-whole-archive -Wl,--whole-archive libmullepbx.a -Wl,--no-whole-archive -Wl,--enable-auto-import -shared-libgcc -fexceptions -fgnu-runtime -L/usr/home/user/GNUstep/Library/Libraries -L/GNUstep/Local/Library/Libraries -L/GNUstep/System/Library/Libraries -lgnustep-base -lobjc -lws2_32 -ladvapi32 -lcomctl32 -luser32 -lcomdlg32 -lmpr -lnetapi32 -lm -I. -o mulle-xcode-to-cmake.exe -Wl,--out-implib,libmulle-xcode-to-cmake.dll.a -Wl,--major-image-version,0,--minor-image-version,0 @CMakeFiles/mulle-xcode-to-cmake.dir/linklibs.rsp
5 / Open linklibs.rsp and delete libmullepbx.a
6 / Now, call make