[CMake] Disable linker / only build object files

[Greg Peele]

Tyler,

I know this isn't exactly what you asked, but have you considered
building each directory into a separate static library that is then
linked into your final library target?  My understanding is that a
static library is essentially just an archive of object files.

-  
Gregory Peele, Jr.
Applied Research Associates, Inc.
(407) 384-2721
gpeele at ara.com


On Wed, Apr 29, 2009 at 7:29 PM, Tyler Roscoe <tyler at cryptio.net> wrote:
        I have a fairly complex library with a bunch of small pieces
        scattered
        throughout subdirectories.
        
        Each subdirectory has its own CMakeLists.txt. This is nice
        because the
        list of .cpp files for each subdirectory is right there in the
        subdirectory, and because these subdirectories behave just like
        all the
        other subdirectories in the system (you can go to them and build
        them
        and get something useful dropped into a results directory).
        
        What I would like is for each subdirectory to compile its .cpp
        files
        into object files and then stop. There is no need for each
        subdir to
        generate a library because the object files will later be
        collected into
        a single higher-level library.
        
        Is there a way to tell CMake to only compile a list of source
        files and
        not to link them? I tried setting CMAKE_CXX_LINK_EXECUTABLE,
        CMAKE_LINKER, and LINKER_LANGUAGE to nothing but the generated
        Makefiles
        still happily call g++.
        
        Should I give up on this approach and just list all my .cpp
        files in the
        CMakeLists for the higher-level. Maybe I could include() stubs
        from the
        subdirectories into my higher-level CMakeLists?
        
        A related problem: how can I get the path to the object files
        that are
        created in my binary directory? We are currently using this, but
        it's
        kinda ugly and probably quite fragile:
        
        if (WIN32)
           set (TEST_OBJ_LOC
        ${${local_project_name}_BINARY_DIR}/${local_project_name}.dir/debug)
           set (OBJ_EXTENSION ${CMAKE_CXX_OUTPUT_EXTENSION})
        else ()
           string(REPLACE "/_build/.." "/" ABS_OBJ_LOC
        ${${local_project_name}_SRC})
           set (TEST_OBJ_LOC
        ${${local_project_name}_BINARY_DIR}/CMakeFiles/${local_project_name}.dir${ABS_OBJ_LOC})
           set (OBJ_EXTENSION .cpp${CMAKE_CXX_OUTPUT_EXTENSION})
        endif ()
        
        
        thanks,
        tyler
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