Hi Justin,
I'm very unsure if this is the correct solution, but it worked for me. I
haven't been able to find any good documentation stating how the CMakeCache
interacts with other parts of CMake.
My assumption is that since CMAKE_C{XX}_FLAGS is supposed to allow the user
to set optional compilation flags, it prefers the value in the cache versus
the one from the toolchain file.
>From one of my toolchain files, reproduce as necessary for CMAKE_C_FLAGS:
SET(CMAKE_CXX_FLAGS "${CMAKE_C_FLAGS} -fno-rtti" CACHE STRING "" FORCE)
Cheers
/Johan
On Mon, Dec 13, 2010 at 4:49 PM, Justin Holewinski <
justin.holewin...@gmail.com> wrote:
> I am experiencing a cross-compiling issue that I believe is related to how
> toolchain files interact with the configure-time compiler checks. For
> reference, I am targeting the iOS 4.2 SDK. I have a toolchain file that
> sets CMAKE_C_FLAGS, CMAKE_CXX_FLAGS, CMAKE_C_LINK_FLAGS, and
> CMAKE_CXX_LINK_FLAGS with appropriate flags for the iOS platform, in
> particular "-arch armv6 -arch armv7". The toolchain file also sets the
> proper C and C++ compilers.
>
> When CMake is executed and the C compiler is tested, the
> toolchain-specified compiler arguments are passed to the link line, but
> *not* the compile line (according to the error output). Since the compile
> line does not contain the "-arch" arguments, the generated object file is
> for i386. However, since the link line contains these flags, the linker
> tries to link ARM code and fails.
>
> Are there any additional variables I should be setting in addition to
> CMAKE_C_FLAGS and CMAKE_CXX_FLAGS in order to get the compiler tests to use
> the right flags? If I add the "-arch" flags using ADD_DEFINITIONS(), they
> are passed to the compiler test and it succeeds. That seems like a hack and
> not a proper solution, though.
>
> Below is the CMake output that prints the values of CMAKE_*_FLAGS as set by
> the toolchain file, as well as the compile and link lines used by CMake.
>
> I am using CMake 2.8.3 on Snow Leopard 10.6.5.
>
> CMake Output:
>
> -- CMAKE_C_FLAGS: -arch armv6 -arch armv7 -pipe -no-cpp-precomp
> --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
> -miphoneos-version-min=4.2
> -- CMAKE_CXX_FLAGS -arch armv6 -arch armv7 -pipe -no-cpp-precomp
> --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
> -miphoneos-version-min=4.2
> -- CMAKE_C_LINK_FLAGS -arch armv6 -arch armv7 -pipe -no-cpp-precomp
> --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
> -miphoneos-version-min=4.2
> -- CMAKE_CXX_LINK_FLAGS -arch armv6 -arch armv7 -pipe -no-cpp-precomp
> --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
> -miphoneos-version-min=4.2
> -- CMAKE_C_FLAGS: -arch armv6 -arch armv7 -pipe -no-cpp-precomp
> --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
> -miphoneos-version-min=4.2
> -- CMAKE_CXX_FLAGS -arch armv6 -arch armv7 -pipe -no-cpp-precomp
> --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
> -miphoneos-version-min=4.2
> -- CMAKE_C_LINK_FLAGS -arch armv6 -arch armv7 -pipe -no-cpp-precomp
> --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
> -miphoneos-version-min=4.2
> -- CMAKE_CXX_LINK_FLAGS -arch armv6 -arch armv7 -pipe -no-cpp-precomp
> --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
> -miphoneos-version-min=4.2
> -- The C compiler identification is GNU
> -- The CXX compiler identification is GNU
> -- Check for working C compiler:
> /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc-4.2
> -- Check for working C compiler:
> /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc-4.2 -- broken
> CMake Error at
> /opt/local/share/cmake-2.8/Modules/CMakeTestCCompiler.cmake:52 (MESSAGE):
> The C compiler
> "/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc-4.2" is not
> able to compile a simple test program.
>
> It fails with the following output:
>
> Change Dir:
> /Users/jholewinski/projects/rapture/build-test/ios/CMakeFiles/CMakeTmp
>
>
>
> Run Build Command:/usr/bin/make "cmTryCompileExec/fast"
>
> /usr/bin/make -f CMakeFiles/cmTryCompileExec.dir/build.make
> CMakeFiles/cmTryCompileExec.dir/build
>
> /opt/local/bin/cmake -E cmake_progress_report
>
>
> /Users/jholewinski/projects/rapture/build-test/ios/CMakeFiles/CMakeTmp/CMakeFiles
> 1
>
> Building C object CMakeFiles/cmTryCompileExec.dir/testCCompiler.c.obj
>
> /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc-4.2
>
>
> -I/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk/usr/include
> -o CMakeFiles/cmTryCompileExec.dir/testCCompiler.c.obj -c
>
>
> /Users/jholewinski/projects/rapture/build-test/ios/CMakeFiles/CMakeTmp/testCCompiler.c
>
>
> Linking C executable cmTryCompileExec
>
> /opt/local/bin/cmake -E cmake_link_script
> CMakeFiles/cmTryCompileExec.dir/link.txt --verbose=1
>
> /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc-4.2 -arch
> armv6 -arch armv7 -pipe -no-cpp-precomp
>
>
> --sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk
> -miphoneos-version-min=4.2
> CMakeFiles/cmTryCompileExec.dir/testCCompiler.c.obj -o cmTryCompileExec
>
>
> -L/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.2.sdk/usr/lib
>
>
> ld: warning: in CMakeFiles/cmTryCompileExec.dir/testCCompiler.c.obj, file
> was built for i386 which is not the architecture being linked (armv6)
>
> Undefined symbols for architecture armv6:
>
> "_main", referenced from:
> start in crt1.3.1.o
>
> ld: symbol(s) not found for architecture armv6
>
> collect2: ld returned 1 exit status
>
> ld: warning: in CMakeFiles/cmTryCompileExec.dir/testCCompiler.c.obj, file
> was built for i386 which is not the architecture being linked (armv7)
>
> Undefined symbols for architecture armv7:
>
> "_main", referenced from:
> start in crt1.3.1.o
>
> ld: symbol(s) not found for architecture armv7
>
> collect2: ld returned 1 exit status
>
> lipo: can't open input file:
> /var/folders/pS/pSWOJvZ-FDS4A2Eo7TwIzE+++TI/-Tmp-//ccKkL4CZ.out (No such
> file or directory)
>
> make[1]: *** [cmTryCompileExec] Error 1
>
> make: *** [cmTryCompileExec/fast] Error 2
>
>
>
>
>
> CMake will not be able to correctly generate this project.
> Call Stack (most recent call first):
> CMakeLists.txt:30 (project)
>
>
> -- Configuring incomplete, errors occurred!
>
>
> --
>
> Thanks,
>
> Justin Holewinski
>
>
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