[CMake] Avoid re-linking dependency of external shared lib in a new project.

[Robert Maynard]

If it is an external library you will need to look at creating import
libraries and packaging targets (
http://www.cmake.org/cmake/help/v3.1/manual/cmake-packages.7.html#manual:cmake-packages(7)
).

On Tue, Mar 3, 2015 at 8:10 PM, Pablo Hernández <
pablo.hernandez.cerdan at outlook.com> wrote:

>  I want to generate in cmake a header-only library from header.h, that
> depends on libboost_system and filesystem. I can compile the library
> without problems with:
>
> find_package(Boost COMPONENTS
>         system filesystem
>         REQUIRED)
> include_directories(SYSTEM ${Boost_INCLUDE_DIRS})
> add_library(mylib SHARED header.h)
> target_link_libraries(mylib PUBLIC ${Boost_LIBRARIES})
> set_target_properties(mylib PROPERTIES LINKER_LANGUAGE CXX)
>
> But when I link to mylib elsewhere, it fails finding the boost library
> with a ld error.
> The failure makes sense, but I don't know how to solve it in CMake. How do
> I "store" the boost dependency on mylib? So I don't have to worry about
> finding the boost library in other external project?
>
> I am using cmake 3.2
> When I use it in other project, the linker is not able to find the boost
> library:
> target_link_libraries(newproject.exe ${external_mylib})
>
> undefined reference to symbol '_ZN5boost6system15system_categoryEv'/PATH/TO/libboost_system-mt-d.so.1.57.0: error adding symbols: DSO missing from command line
> collect2: error: ld returned 1 exit status
>
> It is solved if I explicitly link again to the Boost_LIBRARIES.
> target_link_libraries(newproject.exe ${external_mylib} ${Boost_LIBRARIES))
>
>
> This doesn't avoid finding again the boost_libraries, maybe the solution
> is to put the boost_libraries in the environment variable LD_LIBRARY_PATH?
> Can I avoid relinking to boost somehow?
>
>
> --
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