[CMake] linking: absolute path vs -l<libname>

[Hendrik Sattler]

Hi,

is the netcdf find module defining an imported target? AFAIK, imported targets are always linked by full path. Else the rules already mentioned apply.

HS


Am 28. August 2015 10:23:47 MESZ, schrieb "Nico Schlömer" <nico.schloemer at gmail.com>:
>Hi everyone,
>
>I'm curious about when CMake decides to link a library by its absolute
>path
>and when it links using the `-l*` syntax. I came across this for the
>very
>simple test problem
>```
>cmake_minimum_required(VERSION 3.0)
>
>project(mytest)
>
>find_package(ZLIB REQUIRED)
>find_package(netCDF REQUIRED)
>
>add_executable(mytest main.cpp)
>target_link_libraries(
>  mytest
>  ${ZLIB_LIBRARIES}
>  ${netCDF_LIBRARIES}
>  )
>```
>The resulting link line is
>```
>/usr/bin/c++       CMakeFiles/mytest.dir/main.cpp.o  -o mytest
>-rdynamic
>-lz /usr/lib/x86_64-linux-gnu/libnetcdf.so.7.3.0
>```
>so ZLIB is linked with `-lz`, netCDF with the full absolute path.
>
>Seems inconsistent? (ZLIB by the way is found through CMake's
>FindZLIB.cmake, netCDF by their own export files.)
>
>So far, I had been under the impression that `-l*` defeats the purpose
>of
>CMake a little bit as it asks the linker to search in the system's
>paths
>for a libz.so, something CMake has already done.
>
>A little clarification here would be great.
>
>Cheers,
>Nico
>
>
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