[CMake] Elegant solution for preprocessing a linker script?

[Robert Maynard]

add_dependencies works only on targets not files. You will need to use
add_custom_target whose DEPENDS is set to
${CMAKE_CURRENT_BINARY_DIR}/api.lds. You can than specify that
cmake_test depends on the custom target.

On Fri, Nov 8, 2013 at 5:15 AM, Michael Weise <michael.weise at ek-team.de> wrote:
> On Thu, 7 Nov 2013 19:56:29 +0000
> "Williams, Norman K" <norman-k-williams at uiowa.edu> wrote:
>
>> Why doesn't this work?
>> add_custom_command(
>> ...
>
> Good point, that's the core of my question.
>
> I did implement the "add_custom_command" as you suggested, including
> "dependencies". Unfortunatly, the custom command is not executed.
>
> What happens is:
> ----
> $ rm -rf build-cmake/
> $ mkdir build-cmake
> $ cd build-cmake/
> $ cmake -G "MSYS Makefiles" \
>>  -DCMAKE_TOOLCHAIN_FILE=../src/toolchain-m68k-elf.cmake \
>>  ../src
> -- Configuring done
> -- Generating done
> -- Build files have been written to:
> C:/devel/projekte/cmake_test_custom_command/build-cmake
>
> $ make
> Scanning dependencies of target cmake_test
> [100%] Building C object CMakeFiles/cmake_test.dir/hello.c.obj
> Linking C executable cmake_test
> c:/devel/msys-gcc-m68k-elf/local/coldfire/bin/../lib/gcc/m68k-elf/4.7.3/../../../../m68k-elf/bin/ld.exe:
> cannot open linker script file api.lds: No such file or directory
> ...
> ----
>
> As you can see, the custom command is not executed.
>
>
> File "CMakeLists.txt":
> ----
> project (cmake_test_custom_command)
> cmake_minimum_required (VERSION 2.8)
> set(CMAKE_MAKE_PROGRAM c:/devel/msys-gcc-m68k-elf/bin/make)
>
> add_executable(cmake_test hello.c)
>
> include_directories(inc)
> set(CMAKE_EXE_LINKER_FLAGS "-T api.lds")
>
> add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/api.lds
>                    MAIN_DEPENDENCY ${CMAKE_CURRENT_SOURCE_DIR}/api.lds.S
>                    COMMAND ${CMAKE_C_COMPILER}
>     -E ${CMAKE_CURRENT_SOURCE_DIR}/api.lds.S -P
>     -o ${CMAKE_CURRENT_BINARY_DIR}/api.lds
>     -I ${CMAKE_CURRENT_SOURCE_DIR}/inc
>                    VERBATIM )
>
> add_dependencies(cmake_test ${CMAKE_CURRENT_BINARY_DIR}/api.lds)
> ----
>
>> The actual target that needs the linker script needs to depend on api.lds ...
>
> That's clear (I'm familiar with build systems in general).
> Did I add the dependency (on cmake_test) correctly in my CMakeLists.txt?
> If yes, why is the dependency "not working"?
>
> Best Regards
> Michael
>
>
>
> File "toolchain-m68k-elf.cmake":
> ----
> include(CMakeForceCompiler)
> set(CMAKE_SYSTEM_NAME Generic)
>
> CMAKE_FORCE_C_COMPILER(m68k-elf-gcc GNU)
> CMAKE_FORCE_CXX_COMPILER(m68k-elf-g++ GNU)
>
> set(CMAKE_SYSTEM_PROCESSOR 5372)
> ----
> --
>
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