including itensor library in my cmake project in clion - cmake

Question

so I am very new to CLion and CMake, so sorry in advance for wrong usage of terminology. I am suffering the following problem:
In my project I want to include the ITensor library which is essentially a non-CMake project. I cloned the git to my computer and build the ITensor project. Next I wanted to use it in another project linking against it with CMake:
My Code in main.cpp:
#include <iostream>
#include "itensor.h"
int main() {
std::string some_string = "Hello world";
return 0;
}
and my CMakeLists.txt looks like:
cmake_minimum_required(VERSION 3.6)
project(tutorial)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
set(ITENSOR_DIR PATH/TO/ITENSOR)
include_directories(ITENSOR_DIR/itensor)
set(SOURCE_FILES
main.cpp
${ITENSOR_DIR}/itensor/itensor.h
${ITENSOR_DIR}/itensor/itensor.cc)
add_executable(tutorial ${SOURCE_FILES})
Unfortunately, the project 'tutorial' does not build in CLion. Likewise, CLion cannot resolve the dependency itensor.h.
Anybody an Idea for why this is, respectively how to fix it?

Answer 1

After trying Thomas5631's solution the compilation ran into linking issues with lapack. I solved this by adding some flags, though I'm not sure if all of them are required.
My CMakeLists.txt:
cmake_minimum_required(VERSION 3.6)
project(my_project)
#Bring the headers into the project (full or relative path)
include_directories(itensor)
#Link the Itensor library
add_library(itensor STATIC IMPORTED)
set_property(TARGET itensor PROPERTY IMPORTED_LOCATION /home/david/my_project/itensor/lib/libitensor.a)
#Set a variable with all the new flags
set(ITENSOR_FLAGS "-DPLATFORM_lapack -D__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES=0")
set(ITENSOR_LINK_FLAGS "-DPLATFORM_lapack -L/home/david/my_project/itensor/lib -litensor -lpthread -L/usr/lib -lblas -llapack")
#Append the new flags
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 ${ITENSOR_FLAGS}")
add_executable(my_project main.cpp)
target_link_libraries(my_project itensor "${ITENSOR_LINK_FLAGS}")
Motivation: In the folder itensor/project_template there is a sample program which is simple enough to compile with make (from the terminal). The output of the compilation reveals the flags:
g++ -m64 -std=c++11 -c -I. -I/home/david/my_project/itensor -I/usr/include -O3 -DNDEBUG -Wall -DPLATFORM_lapack -D__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES=0 -Wno-unused-variable -o myappname.o myappname.cc
[... some warnings ...]
g++ -m64 -std=c++11 -c -I. -I/home/david/my_project/itensor -I/usr/include -O3 -DNDEBUG -Wall -DPLATFORM_lapack -D__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES=0 -Wno-unused-variable -o myclass.o myclass.cc
g++ -m64 -std=c++11 -I. -I/home/david/my_project/itensor -I/usr/include -O3 -DNDEBUG -Wall -DPLATFORM_lapack -D__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES=0 -Wno-unused-variable myappname.o myclass.o -o myappname -L/home/david/my_project/itensor/lib -litensor -lpthread -L/usr/lib -lblas -llapack

Answer 2

I got around the issue with the following main.cpp:
#include <iostream>
#include "itensor/itensor.h"
int main() {
std::string some_string = "Hello world";
return 0;
}
And the following CMakeLists.txt:
project(tutorial)
cmake_minimum_required(VERSION 3.6)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
#Bring the headers into the project
include_directories(/home/tom/Documents/workspace/ITensor/)
#Link the library
add_library(itensor STATIC IMPORTED)
set_property(TARGET itensor PROPERTY IMPORTED_LOCATION /home/tom/Documents/workspace/ITensor/lib/libitensor.a)
set(SOURCE_FILES main.cpp)
add_executable(tutorial ${SOURCE_FILES})
Where the path to ITensor can be either relative (using the ${PROJECT_SOURCE_DIR} variable) or absolute as I have shown.