Cannot Configure CLion for Linking C++ - c++

Question

I have a simple c++ example that I am trying to compile on a MacOSX machine using the CLion IDE. The goal is to use header files and cmake to compile this code on CLion with an aim to expand to something bigger and so for now, I have simplified my code to have a bar.h header file and a bar.cpp implementation file. I am getting compilation issues during linking. My code looks as follows:
main.cpp
#include "bar.h"
using namespace std;
int main(int argc, char** argv){
cout<<"starting"<<endl;
Bar bar = Bar("Using Bar Function From Main");
bar.foo();
return 0;
}
CMakeLists.txt
cmake_minimum_required(VERSION 3.21)
set(CMAKE_CXX_STANDARD 11)
project(librarytest)
add_executable(myprog main.cpp)
add_subdirectory(bars)
target_link_libraries(myprog PRIVATE bars)
bars\bar.h
#pragma once
#include <string>
#include <iostream>
class Bar{
private:
std::string s;
public:
Bar(std::string s);
void foo();
};
bars\bar.cpp
#include <string>
#include <iostream>
class Bar{
private:
std::string s;
public:
Bar(std::string s){
std::cout<<"Function Bar"<<std::endl;
this->s = s;
}
void foo(){
std::cout << this->s << std::endl;
}
};
bars\CMakeLists.txt
add_library(bars OBJECT
bar.cpp
)
target_include_directories(bars PUBLIC .)
I get the following error message from my CLion CMake build (I have obfuscated by personal details/directory):
====================[ Build | all | Debug ]=====================================
/Applications/CLion.app/Contents/bin/cmake/mac/bin/cmake --build /{obfuscated-for-security}/testingincludes/cmake-build-debug --target all
[3/3] Linking CXX executable myprog
FAILED: myprog
: && /Library/Developer/CommandLineTools/usr/bin/c++ -g -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX11.3.sdk -Wl,-search_paths_first -Wl,-headerpad_max_install_names bars/CMakeFiles/bars.dir/bar.cpp.o CMakeFiles/myprog.dir/main.cpp.o -o myprog && :
Undefined symbols for architecture x86_64:
"Bar::foo()", referenced from:
_main in main.cpp.o
"Bar::Bar(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >)", referenced from:
_main in main.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.
I have searched other Stack Overflow articles on similar errors but none can explain the issue as it pertains to linking on the OSX. I have followed some of the guidance like re-installing the compiler.
Can anyone suggest how to get this working on the MacOSX using CLion? Any pointers or suggestions would be welcomed.

Answer 1

The problem is not the build (AFAIK), it's the code.
Your bar.cpp file should look like this
#include "bar.h"
#include <string>
#include <iostream>
Bar::Bar(std::string s){
std::cout<<"Function Bar"<<std::endl;
this->s = s;
}
void Bar::foo(){
std::cout << this->s << std::endl;
}
Your version duplicates the Bar class definition in both the header and cpp file. My version includes the Bar class definition and just adds the definitions of the constructor and member function.