[CMake] Sub dependencies?

[Doug]

In the vague hopes that using add_subdirectory() will magically fix things
I've changed the structure to be along the lines of:

exec/CMakeLists.txt
exec/cmake/Modules/Findliba.cmake
exec/deps/liba/CMakeLists.txt
exec/deps/liba/cmake/Modules/Findlibb.cmake
exec/deps/liba/deps/libb/CMakeLists.txt
exec/deps/liba/deps/libb/cmake/Modules/Findlibpng.cmake
exec/deps/liba/deps/libb/cmake/Modules/Findlibpng-android.cmake
external/libpng/...
external/libpng-android/...

I can successfully configure using:

add_subdirectory(deps/Natives/libcommon-android/jni)
find_package(libna REQUIRED)
add_executable(exec ...)
link_target_libraries(exec na)

In libna I have:
message("adding sublibs ${extra_libs}")
link_target_libraries(na ${extra_libs})

and on running cmake it shows:
-- Found LIBZIP
-- Found LIBPNG
adding sublibs
/usr/lib/libSDLmain.a;/usr/lib/libSDL.so;-lpthread;SDLmain;GL;GLU;X11;/usr/lib/libzip.so;/usr/lib/libpng.so

In exec/CMakelists.txt I invoke:
find_package(libna REQUIRED)
message("na depend? ${LIBNA_LIBRARY}")
target_link_libraries(exec ${LIBNA_LIBRARY})

Yielding:
-- Found LIBNA
B depend? /home/doug/projects/Natives/libcommon-android/build/libna.a

However, on compile verbose for exec I still get:
/usr/bin/gcc  -std=c99 -g   CMakeFiles/stars-android.dir/src/main.c.o
CMakeFiles/stars-android.dir/impl/desktop.c.o  -o exec -rdynamic
/home/doug/projects/libn/build/libn.a
/home/doug/projects/libnw/build/libnw.a
/home/doug/projects/libnw-impl/libnw-na/build/libnw-na.a
/home/doug/projects/Natives/libcommon-android/build/libna.a

(The other libraries are fine, only libna has sub-dependencies)

...

:/

Since I invoke:
 target_link_library(na
/usr/lib/libSDLmain.a;/usr/lib/libSDL.so;-lpthread;SDLmain;GL;GLU;X11;/usr/lib/libzip.so;/usr/lib/libpng.so)

and then:
 target_link_library(exec na)

Shouldn't that import those dependencies?

~
Doug.

On Fri, Aug 12, 2011 at 11:23 AM, Doug <douglas.linder at gmail.com> wrote:

> That works if it's all in a single project, but it's not.
>
> I totally understand you can do this:
>
> add_library(foo)
> target_link_library(foo bar)
> add_executable(exec)
> target_link_library(exec foo)
>
> If you have _this_ structure:
>
> .../liba/CMakeLists.txt
> ....
>
> .../blah/libb/CMakeLists.txt
> ....
>
> ..../some/other/path/exec/CMakeLists.txt
>
> Then in exec you can you use find_package(libb REQUIRED)
>
> However, when I compile it I still get dependency resolution errors on liba
> (libpng in my case).
>
> I'm guessing thats because to resolve libb all you get a include path and a
> library path; find package has no way to load the CMakeLists.txt in libb/
> and parse it, add the dependency to liba.
>
> Seems like there should be a way to do this though.
>
> Am I wrong?
>
> Should the values in libb's CMakeLists.txt be propagating through?
>
> If that's supposed to happen I must be using find_package wrong somehow?
>
> In my specific case libpng and libpng-android are not the same project;
> they are completely split and do not even use the same files.
>
> Neither of them are 'child' projects of my library (libnw) via
> add_subdirectory or some other weird thing like that.
>
> ~
> Doug.
>
> On Thu, Aug 11, 2011 at 9:30 PM, Glenn Coombs <glenn.coombs at gmail.com>wrote:
>
>> The target_link_libraries() command would be in the CMakeLists.txt for
>> library A, not the one for your executable.  The one for your executable
>> would just say target_link_libraries(myExe A).  And cmake would
>> automatically know that linking with A also means linking with png.
>>
>> You say that you have 2 different versions of library A.  Does this mean
>> that you have 2 separate CMakeLists.txt files, one for each variant of A.
>> Or are both variants built by the same CMakeLists.txt ?  Either way, I would
>> have thought that you could add the appropriate target_link_libraries()
>> command.  Can you describe your current setup in a bit more detail to
>> explain why this approach won't work ?
>>
>>
>> On 11 August 2011 14:02, Doug <douglas.linder at gmail.com> wrote:
>>
>>> How can I achieve that _without_ editing my own cmake file?
>>>
>>> What if a swap in a different library for my executable that is abi
>>> compatible but uses a different implemented to load images?
>>>
>>> I'm not talking hypotheticals here: I literally have two versions of the
>>> library that use slightly different versions of libpng (one for desktop and
>>> one for android) and it's extremely inconvenient to be messing around with
>>> my cmake file every time I change my build target.
>>>
>>> Sure I can do a giant IF(TARGET MATCHES "Android") ... ENDIF, which I
>>> guess is what I will do for now, but it seems like a poor solution.
>>>
>>> Edit: woops; ment that to go to the list.
>>>
>>> ~
>>> Doug.
>>>
>>> On Thu, Aug 11, 2011 at 7:39 PM, Glenn Coombs <glenn.coombs at gmail.com>wrote:
>>>
>>>> Add the sub dependencies that library A has with
>>>> target_link_libraries():
>>>>
>>>>     target_link_libraries(A png)
>>>>
>>>> --
>>>> Glenn
>>>>
>>>> On 11 August 2011 10:02, Doug <douglas.linder at gmail.com> wrote:
>>>>
>>>>> Hrm... this seems like something cmake should be able to do, but I
>>>>> don't know how to make it work.
>>>>>
>>>>> If I have library A, that depends on a library and an executable
>>>>> project that depends on library A, how can the executable project resolve
>>>>> the sub dependencies from A?
>>>>>
>>>>> Specifically libpng in my case:
>>>>>
>>>>> I have a library that depends on libpng.
>>>>>
>>>>> I run cmake to build the library no problem.
>>>>>
>>>>> Then I try to compile a program that depends on the library and get a
>>>>> heap of errors like:
>>>>>
>>>>>  undefined reference to `png_set_read_fn'
>>>>>  etc. etc.
>>>>>
>>>>> Presumably this is something about how I depend on the library? I'm
>>>>> using the LibFindMacros, so my cmake module looks like this for the library:
>>>>>
>>>>> include(LibFindMacros)
>>>>>
>>>>> find_path(LIBNW_INCLUDE_DIR NAMES nw.h PATHS
>>>>> ${LIBNW_PKGCONF_INCLUDE_DIRS})
>>>>>
>>>>> find_library(LIBNW_LIBRARY NAMES nw PATHS
>>>>> ${LIBNW_PKGCONF_LIBRARY_DIRS})
>>>>>
>>>>> set(LIBNW_PROCESS_INCLUDES LIBNW_INCLUDE_DIR)
>>>>> set(LIBNW_PROCESS_LIBS LIBNW_LIBRARY LIBNW_LIBRARIES)
>>>>>
>>>>> libfind_process(LIBNW)
>>>>>
>>>>>  I know I can use ADD_SUBDIRECTORY to include stuff for a sub dir, but
>>>>> that isn't really appropriate in this case.
>>>>>
>>>>> ~
>>>>> Doug.
>>>>>
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>>>>
>>>>
>>>
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>>
>>
>
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