Pass linker flags in CMake for CPLEX - c++

Question

In short: I can't link my program that uses CPLEX with CMake, the linker doesn't seem to find a CPLEX library (cplex), but finds some others (ilocplex). From the command line, it does work.
Detailed:
For the program using CPLEX:
#include <ilcplex/ilocplex.h>
int main(int argc, char *argv[]) {
IloEnv env;
IloModel model(env);
IloCplex cplex(model);
return 0;
}
I have the following CMakeLists.txt:
cmake_minimum_required(VERSION 3.17)
project(myprog C CXX)
set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_POSITION_INDEPENDENT_CODE ON)
set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
find_package(CPLEX)
if (CPLEX_FOUND)
add_definitions(-DIL_STD)
else()
message (FATAL_ERROR "CPLEX not found!")
endif()
add_executable(myprog src/main.cpp )
target_include_directories(myprog PUBLIC ${CPLEX_INCLUDE_DIRS})
target_link_libraries(myprog PUBLIC ${CPLEX_LIBRARIES})
set_target_properties(myprog PROPERTIES LINK_FLAGS "-lconcert -lilocplex -lcplex -lpthread -ldl")
and cmake/FindCPLEX.cmake:
set (CPLEX_DIR "/opt/ibm/ILOG/CPLEX_Studio_Community201")
if (CPLEX_INCLUDE_DIR)
set(CPLEX_FOUND TRUE)
set(CPLEX_INCLUDE_DIRS "${CPLEX_INCLUDE_DIR};${CPLEX_CONCERT_INCLUDE_DIR}" )
set(CPLEX_LIBRARIES "${CPLEX_ILO_LIBRARY};${CPLEX_CONCERT_LIBRARY};${CPLEX_LIBRARY};${CPLEX_PTHREAD_LIBRARY}" )
else (CPLEX_INCLUDE_DIR)
find_path(CPLEX_INCLUDE_DIR
NAMES ilcplex/cplex.h
PATHS "${CPLEX_DIR}/cplex/include"
)
find_path(CPLEX_INCLUDE_ILCPLEX
NAMES cplex.h
PATHS "${CPLEX_DIR}/cplex/include/ilcplex"
)
find_path(CPLEX_CONCERT_INCLUDE_DIR
NAMES ilconcert/ilomodel.h
PATHS "${CPLEX_DIR}/concert/include"
)
find_path(CPLEX_INCLUDE_ILCONCERT
NAMES ilomodel.h
PATHS "${CPLEX_DIR}/concert/include/ilconcert"
)
find_library(CPLEX_LIBRARY
cplex
PATHS "${CPLEX_DIR}/cplex/lib/x86-64_sles10_4.1/static_pic"
"${CPLEX_DIR}/cplex/lib/x86-64_darwin/static_pic/"
"${CPLEX_DIR}/cplex/lib/x86-64_linux/static_pic"
)
find_library(CPLEX_ILO_LIBRARY
ilocplex
PATHS "${CPLEX_DIR}/cplex/lib/x86-64_sles10_4.1/static_pic"
"${CPLEX_DIR}/cplex/lib/x86-64_darwin/static_pic/"
"${CPLEX_DIR}/cplex/lib/x86-64_linux/static_pic"
)
find_library(CPLEX_CONCERT_LIBRARY
concert
PATHS "${CPLEX_DIR}/concert/lib/x86-64_linux/static_pic/"
"${CPLEX_DIR}/concert/lib/x86-64_sles10_4.1/static_pic"
"${CPLEX_DIR}/concert/lib/x86-64_darwin/static_pic/"
)
find_library( CPLEX_PTHREAD_LIBRARY
pthread
PATHS "/usr/lib"
"/usr/lib64"
"/lib"
"/lib64"
)
find_library( CPLEX_DL_LIBRARY
dl
PATHS "/usr/lib"
"/usr/lib64"
"/lib"
"/lib64"
)
set(CPLEX_COMPILER_FLAGS "-DIL_STD" CACHE STRING "Cplex Compiler Flags")
include(FindPackageHandleStandardArgs)
find_package_handle_standard_args(CPLEX DEFAULT_MSG
CPLEX_LIBRARY CPLEX_INCLUDE_DIR CPLEX_CONCERT_INCLUDE_DIR CPLEX_ILO_LIBRARY CPLEX_CONCERT_LIBRARY)
if(CPLEX_FOUND)
set(CPLEX_INCLUDE_DIRS "${CPLEX_INCLUDE_DIR};${CPLEX_CONCERT_INCLUDE_DIR};${CPLEX_INCLUDE_ILCPLEX};${CPLEX_INCLUDE_ILCONCERT}" )
set(CPLEX_LIBRARIES ${CPLEX_CONCERT_LIBRARY} ${CPLEX_ILOCPLEX_LIBRARY} ${CPLEX_LIBRARY} ${CPLEX_PTHREAD_LIBRARY} ${CPLEX_DL_LIBRARY})
endif(CPLEX_FOUND)
mark_as_advanced(CPLEX_INCLUDE_DIR CPLEX_LIBRARY CPLEX_CONCERT_INCLUDE_DIR CPLEX_ILO_LIBRARY CPLEX_CONCERT_LIBRARY CPLEX_PTHREAD_LIBRARY)
endif(CPLEX_INCLUDE_DIR)
message(STATUS "CPLEX_ILO_LIBRARY=${CPLEX_ILO_LIBRARY}")
message(STATUS "CPLEX_LIBRARIES=${CPLEX_LIBRARIES}")
message(STATUS "CPLEX_INCLUDE_DIRS=${CPLEX_INCLUDE_DIRS}")
message(STATUS "concert=${concert}")
message(STATUS "cplex=${cplex}")
The CPLEX related CMake output is
-- Found CPLEX: /opt/ibm/ILOG/CPLEX_Studio_Community201/cplex/lib/x86-64_linux/static_pic/libcplex.a
-- CPLEX_ILO_LIBRARY=/opt/ibm/ILOG/CPLEX_Studio_Community201/cplex/lib/x86-64_linux/static_pic/libilocplex.a
-- CPLEX_LIBRARIES=/opt/ibm/ILOG/CPLEX_Studio_Community201/concert/lib/x86-64_linux/static_pic/libconcert.a;/opt/ibm/ILOG/CPLEX_Studio_Community201/cplex/lib/x86-64_linux/static_pic/libcplex.a;/usr/lib/x86_64-linux-gnu/libpthread.so;/usr/lib/x86_64-linux-gnu/libdl.so
-- CPLEX_INCLUDE_DIRS=/opt/ibm/ILOG/CPLEX_Studio_Community201/cplex/include;/opt/ibm/ILOG/CPLEX_Studio_Community201/concert/include;/opt/ibm/ILOG/CPLEX_Studio_Community201/cplex/include/ilcplex;/opt/ibm/ILOG/CPLEX_Studio_Community201/concert/include/ilconcert
-- concert=
-- cplex=
The error is
/usr/bin/ld: cannot find -lconcert
/usr/bin/ld: cannot find -lilocplex
/usr/bin/ld: cannot find -lcplex
Without the last line in CMakeLists.txt, the error is
/usr/bin/ld: CMakeFiles/myprog.dir/src/main.cpp.o: in function `main':
/<my path>/src/main.cpp:7: undefined reference to `IloCplex::IloCplex(IloModel)'
that is the linker finds the class IloEnv in /opt/ibm/ILOG/CPLEX_Studio_Community201/concert/include/ilconcert/iloenv.h and IloModel in /opt/ibm/ILOG/CPLEX_Studio_Community201/concert/include/ilconcert/ilomodel.h but not IloCplex in /opt/ibm/ILOG/CPLEX_Studio_Community201/cplex/include/ilcplex/ilocplexi.h.
Compiling from the command line works (formatted here for ease of reading):
$ for f in src/*.cpp; do
... g++ -c -I/opt/ibm/ILOG/CPLEX_Studio_Community201/cplex/include
... -I/opt/ibm/ILOG/CPLEX_Studio_Community201/concert/include
... -Iinclude $f -o build/$(basename $f .cpp).o;
... done
$ unset OBJ_FILES
$ for i in build/*.o; do OBJ_FILES="$i $OBJ_FILES"; done
$ g++ -I/opt/ibm/ILOG/CPLEX_Studio_Community201/cplex/include
... -I/opt/ibm/ILOG/CPLEX_Studio_Community201/concert/include
... -Iinclude
... -L/opt/ibm/ILOG/CPLEX_Studio_Community201/cplex/lib/x86-64_linux/static_pic
... -L/opt/ibm/ILOG/CPLEX_Studio_Community201/concert/lib/x86-64_linux/static_pic
... $OBJ_FILES
... -o progr
... -lconcert -lilocplex -lcplex -lpthread -ldl

Answer 1

As Tsyvarev noted: instead of using CPLEX_ILOCPLEX_LIBRARY that is nowhere set, the variable CPLEX_ILO_LIBRARY should be used in the definition of CPLEX_LIBRARIES.