[CMake] How to get a list of all the static libraries that a target will link against ?

[Glenn Coombs]

The problem is that I need to add both -whole-archive and -no-whole-archive
options.  And I need to control exactly where they occur so that only my
libraries occur inside the whole archive section.  I'd be happy to be
proven wrong but I don't think setting CMAKE_EXE_LINKER_FLAGS will give me
that level of control.

--
Glenn


On 21 July 2014 09:57, Angeliki Chrysochou <angeliki.chrysochou at gmail.com>
wrote:

> Hi Glenn,
>
> Adding linker flags exactly in target_link_libraries is not a very good
> practice in my opinion. To add specific linker flags to an executable, you
> can use the variable CMAKE_EXE_LINKER_FLAGS, which you can edit before
> calling add_executable. You could set this variable accordingly in your
> static and dynamic CMakeLists.txt to include the flags you wish in the
> following way:
>
> set(CMAKE_EXE_LINKER_FLAGS "-whole-archive")
>
> If you set this variable to include more custom linker flags which you
> want to preserve across libraries, then you should set it in the following
> way to preserve its old value:
>
> set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -whole-archive")
>
> If you want to edit linker flags for a shared library or a module target
> you can use these cmake variables (set them before add_library):
>
> CMAKE_SHARED_LINKER_FLAGS
> CMAKE_MODULE_LINKER_FLAGS
>
> Be aware that variables have CMakeLists.txt file scope, so if you set
> different values in one CMakeLists.txt then they might get overwritten or
> appended (depending on the way you edit the variable).
>
> All the best,
> Angeliki
>
>
>
>
>
> On Sat, Jul 19, 2014 at 2:39 PM, Glenn Coombs <glenn.coombs at gmail.com>
> wrote:
>
>> Don't all shout at once :-)  I'm guessing there are no easy solutions
>> then...
>>
>> --
>> Glenn
>>
>>
>> On 28 June 2014 14:33, Glenn Coombs <glenn.coombs at gmail.com> wrote:
>>
>>> I have a project which compiles and links into both a stand alone
>>> executable and a dynamic shared library.  The library and the executable
>>> link against the same project libraries but have different object files
>>> containing their entry points: main.o for the executable and dll_main.o for
>>> the library.  My project heirarchy looks like this (simplified a bit for
>>> brevity):
>>>
>>> CMakeLists.txt
>>>     mtx_source/CMakeLists.txt
>>>     mtx_wrapper/CMakeLists.txt
>>>     testbench/CMakeLists.txt
>>>
>>> The top level CMakeLists.txt calls add_subdirectory on the various
>>> project specific library folders which each build a static library.  The
>>> testbench folder is the one that builds both the executable and the dynamic
>>> library.  When building the dynamic library I need to use the linker
>>> options -whole-archive and -no-whole-archive to force my static project
>>> libraries to be included into the dynamic library. The problem is how to
>>> insert the -whole-archive and -no-whole-archive options so that they select
>>> the correct set of libraries.  Currently in the testbench CMakeLists.txt
>>> file I have these lines:
>>>
>>> set(libs
>>>     VLC
>>>     mvea
>>>     ${SYSTEMC_SUPPORT_LIBRARIES}
>>>     ${DEVIFSLAVE_LIBRARIES}
>>>     ${SYSTEMC_LIBRARIES}
>>>     ${SIM_UTILS_LIBRARIES}
>>>     ${HWDEBUG_LIBRARIES}
>>> )
>>>
>>> if (NOT STUB_OUT_MTX)
>>>     list(APPEND libs mtx_wrapper)
>>> endif()
>>>
>>> set(libs_dll ${libs} transif_slave)
>>>
>>> if (UNIX)
>>>     list(INSERT libs_dll 0 -Wl,-whole-archive)
>>>     list(APPEND libs_dll   -Wl,-no-whole-archive)
>>> endif()
>>>
>>> add_library ( csim_dll SHARED ${sources_dll} ${headers_dll} )
>>> add_executable( testbench       ${sources}     ${headers}     )
>>>
>>> target_link_libraries(csim_dll  ${libs_dll} ${PTHREADS_LIBRARIES} )
>>> target_link_libraries(testbench ${libs}     ${PTHREADS_LIBRARIES} )
>>>
>>> which produces the following link line:
>>>
>>> /usr/bin/g++-4.7  -fPIC -m32  -m32 -m32 -fPIC -m32 -O3  -O3 -DHIDEBUG
>>> -Wl,-Bsymbolic
>>> -shared -Wl,-soname,libtopazhp.so
>>> -o libtopazhp.so
>>> CMakeFiles/csim_dll.dir/dll_main.cpp.o
>>> CMakeFiles/csim_dll.dir/main_common.cpp.o
>>> -lm -lrt -lm -lrt
>>> -Wl,-whole-archive
>>> ../mvea/VLC/libVLC.a
>>> ../mvea/libmvea.a
>>> ../systemCSupport/libsystemc_support.a
>>> ../devif_slave/libDevifSlave.a
>>> ../systemC/libsystemc.a
>>> ../sim_utils/libsim_utils.a
>>> ../hwdebug/libhwDebug.a
>>> ../mtx_wrapper/libmtx_wrapper.a
>>> ../transif/libtransif_slave.a
>>> -Wl,-no-whole-archive
>>> -lpthread -lz
>>> ../systemC/libpthreads_dummy.a
>>> ../external_mtx/src/external_mtx-build/metag/libmetag.a
>>> ../external_mtx/src/external_mtx-build/metagcopro/libmetagcopro.a
>>> ../external_mtx/src/external_mtx-build/metac/vmetastub/libvmetastub.a
>>> ../external_mtx/src/external_mtx-build/metac/insim/libinsimfpu.a
>>> ../external_mtx/src/external_mtx-build/mtx/insim-mtxg/libinsim-mtxg.a
>>> ../external_mtx/src/external_mtx-build/mtx/libmtxc.a
>>> -ldl -lm -lrt -lm -lrt
>>>
>>> The problem is that the 6 external_mtx libraries should have been
>>> included inside the -whole-archive section.  These libraries are specified
>>> in the mtx_wrapper folder with a target_link_libraries(mtx_wrapper
>>> ${METASIM_LIBRARIES}) command.  I have managed to wrap the direct library
>>> dependencies inside the -whole-archive but I need to ensure that any
>>> sub-dependencies are included as well (and any dependencies they might have
>>> recursively).  Any system dynamic libaries (-ldl -lm -lrt etc.) must appear
>>> after the -no-whole-archive option otherwise the link fails.  The
>>> mtx_wrapper library can be built in two ways and only one of them will add
>>> the extra METASIM libraries as a dependency, the other way fakes that code
>>> internally.  Adding the METASIM libraries via target_link_libraries()
>>> inside the mtx_wrapper CMakeLists.txt correctly handles that dependency
>>> when linking the standalone executable but is not working for linking the
>>> dynamic library.
>>>
>>> Is there an easy way to get cmake to handle all this ?  Is there a way
>>> to get a list of all the static libraries (libXXX.a) that will be included
>>> on the link line for a target ?
>>>
>>> --
>>> Glenn
>>>
>>>
>>
>> --
>>
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