CMake not compile on raspberry - c

Question

I'm new with cmake.
With cmake I was able to compile my project on my laptop, but on the raspberry is not working.
This is the error i get on raspberry:
-- The C compiler identification is GNU 4.9.2
-- The CXX compiler identification is GNU 4.9.2
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.28")
-- checking for one of the modules 'glib-2.0'
-- Found GLib: /usr/lib/arm-linux-gnueabihf/libglib-2.0.so (found version "2.42.1")
-- Found mhd: /usr/include
CMake Error at cmake/FindGLIB.cmake:39 (add_library): add_library cannot create imported target "glib-2.0" because another target with the same name already exists.
Call Stack (most recent call first):librerie/CMakeLists.txt:2 (find_package)
-- Found GLib: /usr/lib/arm-linux-gnueabihf/libglib-2.0.so (found version "2.42.1")
-- Configuring incomplete, errors occurred!
See also "/home/pi/pl1/CMakeFiles/CMakeOutput.log".
This is my project structure:
src->
---- CMakeLists.txt
---- main.c
---- librerie->
-------------- CMakeLists.txt
-------------- cJSON.c
-------------- cJSON.h
-------------- config.c
-------------- config.h
-------------- server_web.c
-------------- server_web.h
-------------- funzioni_thread.c
-------------- funzioni_thread.h
---- cmake->
-------------- FindGLIB.cmake
-------------- FindMHD.cmake
This is First CMakeLists :
cmake_minimum_required (VERSION 2.6)
project (TestPL)
include_directories("${PROJECT_BINARY_DIR}")
list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake")
find_package(GLIB REQUIRED)
find_package(MHD REQUIRED)
add_subdirectory (librerie)
set (EXTRA_LIBS ${EXTRA_LIBS} librerie)
include_directories (${GLib_INCLUDE_DIRS} ${EXTRA_LIBS})
# add the executable
add_executable(TestPL main.c)
target_link_libraries (TestPL ${GLib_LIBRARY} ${MHD_LIBRARY} ${EXTRA_LIBS} m)
This is CMakeLists in librerie directory:
find_package(GLIB REQUIRED)
find_package(MHD REQUIRED)
include_directories (${GLib_INCLUDE_DIRS} ${EXTRA_LIBS})
add_library (librerie cJSON.c config.c generic.c server_web.c funzioni_thread.c)
target_link_libraries (librerie ${GLib_LIBRARY} ${MHD_LIBRARY})
What am I doing wrong?

Answer 1

You call twice
find_package(GLIB REQUIRED)
First time it is called from top-level CMakeLists.txt and defines glib-2.0 target. Second time it is called from librerie/CMakeLists.txt and attempt to create glib-2.0 again. That is why you see that error message: the target is already defined in this scope.
Possible workaround is to step into library subdirectory first, and only then call find_package() in top-level CMakeLists.txt:
add_subdirectory (librerie)
find_package(GLIB REQUIRED)
find_package(MHD REQUIRED)
Because IMPORTED targets has local visibility, glib-2.0 target defined by find_package(GLIB) call from subdirectory librerie/ will not be visible after returning from this subdirectory. So the second call from top-level directory will succeed.