CMake: cannot create target because another target with the same name already exists - cmake

Question

I'm trying to install plexe-sumo with cmake. I followed the tutorial at plexe.car2x.org and here's the results:
-- CMAKE_BUILD_TYPE: Release
-- CMAKE_BINARY_DIR: /home/cc/src/plexe-sumo/build-release
-- CMAKE_SOURCE_DIR: /home/cc/src/plexe-sumo
--
-- Platform:
-- Host: Linux4.15.0-34-genericx86_64
-- CMake: 3.12.2
-- CMake generator: Unix Makefiles
-- CMake build tool: /usr/bin/make
--
-- Found Proj: /usr/lib/x86_64-linux-gnu/libproj.so
CMake Error at /usr/local/share/cmake-3.12/Modules/UseSWIG.cmake:627 (add_custom_target):
add_custom_target cannot create target "libsumo_swig_compilation" because
another target with the same name already exists. The existing target is a
custom target created in source directory
"/home/cc/src/plexe-sumo/src/libsumo". See documentation for policy
CMP0002 for more details.
Call Stack (most recent call first):
src/libsumo/CMakeLists.txt:39 (SWIG_ADD_LIBRARY)
-- Enabled features: Linux-4.15.0-34-generic Proj GUI GDAL OSG GL2PS SWIG
-- Configuring incomplete, errors occurred!
There is no file named 'libsumo_swig_compilation' under "/home/cc/src/plexe-sumo/src/libsumo".
Then I checked the error log file, but the errors shown are about pthread saying 'undefined reference to pthread_creat' and 'cannot find -lpthreads'. Actually my pthread library is installed at 'libc6: /lib/x86_64-linux-gnu/libpthread.so.0'.
So I was wondering what's the exact problem here and how to solve it. I'm using a virtual machine with ubuntu 16. I appreciate your help!
Following is the error log file:
Determining if the pthread_create exist failed with the following output:
Change Dir: /home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp
Run Build Command:"/usr/bin/make" "cmTC_050d5/fast"
/usr/bin/make -f CMakeFiles/cmTC_050d5.dir/build.make CMakeFiles/cmTC_050d5.dir/build
make[1]: Entering directory '/home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_050d5.dir/CheckSymbolExists.c.o
/usr/bin/cc -Wall -pedantic -Wextra -o CMakeFiles/cmTC_050d5.dir/CheckSymbolExists.c.o -c /home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp/CheckSymbolExists.c
/home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp/CheckSymbolExists.c: In function ‘main’:
/home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp/CheckSymbolExists.c:8:11: warning: ISO C forbids conversion of function pointer to object pointer type [-Wpedantic]
return ((int*)(&pthread_create))[argc];
^
Linking C executable cmTC_050d5
/usr/local/bin/cmake -E cmake_link_script CMakeFiles/cmTC_050d5.dir/link.txt --verbose=1
/usr/bin/cc -Wall -pedantic -Wextra -rdynamic CMakeFiles/cmTC_050d5.dir/CheckSymbolExists.c.o -o cmTC_050d5
CMakeFiles/cmTC_050d5.dir/CheckSymbolExists.c.o: In function `main':
CheckSymbolExists.c:(.text+0x16): undefined reference to `pthread_create'
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_050d5.dir/build.make:86: recipe for target 'cmTC_050d5' failed
make[1]: *** [cmTC_050d5] Error 1
make[1]: Leaving directory '/home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp'
Makefile:121: recipe for target 'cmTC_050d5/fast' failed
make: *** [cmTC_050d5/fast] Error 2
File /home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp/CheckSymbolExists.c:
/* */
#include <pthread.h>
int main(int argc, char** argv)
{
(void)argv;
#ifndef pthread_create
return ((int*)(&pthread_create))[argc];
#else
(void)argc;
return 0;
#endif
}
Determining if the function pthread_create exists in the pthreads failed with the following output:
Change Dir: /home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp
Run Build Command:"/usr/bin/make" "cmTC_9f654/fast"
/usr/bin/make -f CMakeFiles/cmTC_9f654.dir/build.make CMakeFiles/cmTC_9f654.dir/build
make[1]: Entering directory '/home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_9f654.dir/CheckFunctionExists.c.o
/usr/bin/cc -Wall -pedantic -Wextra -DCHECK_FUNCTION_EXISTS=pthread_create -o CMakeFiles/cmTC_9f654.dir/CheckFunctionExists.c.o -c /usr/local/share/cmake-3.12/Modules/CheckFunctionExists.c
Linking C executable cmTC_9f654
/usr/local/bin/cmake -E cmake_link_script CMakeFiles/cmTC_9f654.dir/link.txt --verbose=1
/usr/bin/cc -Wall -pedantic -Wextra -DCHECK_FUNCTION_EXISTS=pthread_create -rdynamic CMakeFiles/cmTC_9f654.dir/CheckFunctionExists.c.o -o cmTC_9f654 -lpthreads
/usr/bin/ld: cannot find -lpthreads
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_9f654.dir/build.make:86: recipe for target 'cmTC_9f654' failed
make[1]: *** [cmTC_9f654] Error 1
make[1]: Leaving directory '/home/cc/src/plexe-sumo/build-release/CMakeFiles/CMakeTmp'
Makefile:121: recipe for target 'cmTC_9f654/fast' failed
make: *** [cmTC_9f654/fast] Error 2

Answer 1

My assumption is that this is really a behavior which only the new cmake shows. You could try to rename all references to libsumo in the java part of the CMakeLists.txt or simply use the CMakeLists of the main line sumo here: https://github.com/eclipse/sumo/blob/master/src/libsumo/CMakeLists.txt