C++: How to properly link compiled object using CMake in VSCode - c++

Question

OS
Windows 10
CMake: 3.16.3
Editor
VSCode: 1.48.1
Extensions
CMake Tools: 1.4.1
C/C++ 0.30.0-insiders3
Kit
Visual Studio Community 2019 Release - amd64
Project Repo
https://gitlab.com/NumeralRocket/kepler Removed, insufficient for minimal reproducible example
Tutorial
Introduction to Google Test and CMake
https://www.youtube.com/watch?v=Lp1ifh9TuFI
I'm attempting to build unit tests for one of my personal projects using CMake, and while I wholly admit I am quite new to CMake and a novice at C++, I am stumped on how to resolve this problem. When I go to build my project I get the following Linker error:
[main] Building folder: kepler
[build] Starting build
[proc] Executing command: "C:\Program Files\CMake\bin\cmake.EXE" --build n:/Unreal_Engine/Magellan/kepler/build-vscode --config Debug --target ALL_BUILD -- /maxcpucount:14
[build] Microsoft (R) Build Engine version 16.6.0+5ff7b0c9e for .NET Framework
[build] Copyright (C) Microsoft Corporation. All rights reserved.
[build]
[build] gmock.vcxproj -> N:\Unreal_Engine\Magellan\kepler\build-vscode\lib\Debug\gmockd.lib
[build] gmock_main.vcxproj -> N:\Unreal_Engine\Magellan\kepler\build-vscode\lib\Debug\gmock_maind.lib
[build] kepler.vcxproj -> N:\Unreal_Engine\Magellan\kepler\build-vscode\Debug\kepler.lib
[build] gtest.vcxproj -> N:\Unreal_Engine\Magellan\kepler\build-vscode\lib\Debug\gtestd.lib
[build] gtest_main.vcxproj -> N:\Unreal_Engine\Magellan\kepler\build-vscode\lib\Debug\gtest_maind.lib
[build] LINK : fatal error LNK1104: cannot open file 'Quaternion.lib' [N:\Unreal_Engine\Magellan\kepler\build-vscode\test\QuaternionTests.vcxproj]
[cmakefileapi-parser] Code model version (2.1) of cmake-file-api is unexpected. Expecting (2.0). IntelliSense configuration may be incorrect.
[cmakefileapi-parser] Code model version (2.1) of cmake-file-api is unexpected. Expecting (2.0). IntelliSense configuration may be incorrect.
[build] Build finished with exit code 1
For context, the project is structured as follows:
${ProjectRoot}
├── CMakeLists.txt
├── Quaternion.cpp
├── Quaternion.hpp
├── googletest
└── test
├── CMakeLists.txt
└── QuaternionTest.cpp
${ProjectRoot}/CMakeLists.txt
cmake_minimum_required(VERSION 3.16) # version can be different
set(CMAKE_VERBOSE_MAKEFILE ON)
set(This kepler)
get_filename_component(CODE_ROOT ${CMAKE_CURRENT_SOURCE_DIR} DIRECTORY)
project(${This}) #name of your project
project(${This} C CXX)
set(CMAKE_C_STANDARD 99)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_POSITION_INDEPENDENT_CODE ON)
enable_testing()
add_subdirectory(googletest)
add_subdirectory(test)
set(Headers
Quaternion.hpp
)
set(Sources
Quaternion.cpp
)
add_library(${This} STATIC ${Sources} ${Headers})
${ProjectRoot}/Quaternion.cpp
#include <iostream>
#include "Quaternion.hpp"
// Default Constructor
Quaternion::Quaternion() {}
// Specified Value Constructor
Quaternion::Quaternion(double qs, double qi, double qj, double qk) : q0(qs), q1(qi), q2(qj), q3(qk) {}
Quaternion operator + (Quaternion const &quatA, Quaternion const &quatB) // 1) § 5.3
{
Quaternion quatC;
quatC.q0 = quatA.q0 + quatB.q0;
quatC.q1 = quatA.q1 + quatB.q1;
quatC.q2 = quatA.q2 + quatB.q2;
quatC.q3 = quatA.q3 + quatB.q3;
return quatC;
}
Quaternion operator - (Quaternion const &quatA, Quaternion const &quatB) // 1) § 5.3
{
Quaternion quatC;
quatC.q0 = quatA.q0 - quatB.q0;
quatC.q1 = quatA.q1 - quatB.q1;
quatC.q2 = quatA.q2 - quatB.q2;
quatC.q3 = quatA.q3 - quatB.q3;
return quatC;
}
void QuaternionLog(Quaternion quat2log)
{
std::cout << "q0: " << quat2log.q0 << std::endl;
std::cout << "q1: " << quat2log.q1 << std::endl;
std::cout << "q2: " << quat2log.q2 << std::endl;
std::cout << "q3: " << quat2log.q3 << std::endl;
}
int main()
{
Quaternion quat1;
Quaternion quat2(1, 2, 3, 4);
Quaternion quat3 = quat1 + quat2;
Quaternion quat4 = quat1 - quat2;
QuaternionLog(quat1);
QuaternionLog(quat2);
QuaternionLog(quat3);
QuaternionLog(quat4);
}
${ProjectRoot}/Quaternion.hpp
#ifndef QUATERNION_H
#define QUATERNION_H
class Quaternion
{
public:
double q0{ 1.0 };
double q1{ 0.0 };
double q2{ 0.0 };
double q3{ 0.0 };
Quaternion();
Quaternion(double qs, double qi, double qj, double qk);
friend Quaternion operator + (Quaternion const &quatA, Quaternion const &quatB);
friend Quaternion operator - (Quaternion const &quatA, Quaternion const &quatB);
};
#endif /* QUATERNION_H */
${ProjectRoot}/test/CMakeLists.txt
cmake_minimum_required(VERSION 3.16)
set(This QuaternionTests)
set(Sources
QuaternionTest.cpp
)
add_executable(${This} ${Sources})
target_link_libraries(${This} PUBLIC
gtest_main
Quaternion
)
add_test(
NAME ${This}
COMMAND ${This}
)
${ProjectRoot}/test/QuaternionTest.cpp
#include <gtest/gtest.h>
#include "../Quaternion.hpp"
TEST(Quaternion, QuaternionConstructors)
{
Quaternion test_quat_1;
ASSERT_EQ(test_quat_1.q0, 1);
ASSERT_EQ(test_quat_1.q1, 0);
ASSERT_EQ(test_quat_1.q2, 0);
ASSERT_EQ(test_quat_1.q3, 0);
ASSERT_EQ(1,1);
};
int main(int argc, char **argv)
{
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
};
How can I:
Ensure and Inspect that objects are being built appropriately?
Properly instruct CMake such that the linker can find my Quaternion (source code) object?
Any insight would be appreciated.

Answer 1

My mistake was in adding my library incorrectly:
${ProjectRoot}/CMakeLists.txt
cmake_minimum_required(VERSION 3.16) # version can be different
set(CMAKE_VERBOSE_MAKEFILE ON)
set(This kepler)
get_filename_component(CODE_ROOT ${CMAKE_CURRENT_SOURCE_DIR} DIRECTORY)
project(${This}) #name of your project
project(${This} C CXX)
set(CMAKE_C_STANDARD 99)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_POSITION_INDEPENDENT_CODE ON)
enable_testing()
add_subdirectory(googletest)
add_subdirectory(test)
set(Headers
Quaternion.hpp
)
set(Sources
Quaternion.cpp
)
add_library(${This} STATIC ${Sources} ${Headers})
I was adding a library named ${THIS} which was "kepler" instead of the expected "Quaternion", so:
add_library(Quaternion STATIC ${Sources} ${Headers})
correctly tells the linker what/where to expect my library
AND
Leaving a main function in Quaternion.cpp, which was removed
Solution Source: vector-of-bool