Singleton idiom example in C++

CMakeLists.txt

cmake_minimum_required(VERSION 3.16)
project(singleton_idiom)

set(CMAKE_CXX_STANDARD 17)
add_library(singleton singleton.cpp)

add_executable(singleton_idiom main.cpp)
target_link_libraries(singleton_idiom singleton)

main.cpp

#include "singleton.h"
#include <iostream>

static Singleton &singleton = Singleton::GetInstance();

int main() {
    std::cout << "Hello, World!" << std::endl;
    return 0;
}

singleton.cpp

//
// Created by angelos on 03/06/2020.
//
#include "singleton.h"


Singleton &Singleton::GetInstance() {
    std::mutex mutex;
    std::scoped_lock lock(mutex);

    static Singleton instance;
    return instance;
}

singleton.h

//
// Created by angelos on 03/06/2020.
//

#ifndef SINGLETON_IDIOM_SINGLETON_H
#define SINGLETON_IDIOM_SINGLETON_H
#include <mutex>
#include <thread>

class Singleton {
public:
    static Singleton &GetInstance();

    Singleton(const Singleton &) = delete;
    Singleton &operator=(const Singleton &) = delete;
    Singleton(Singleton&& ) = delete;
    Singleton& operator=(Singleton&& ) = delete;

private:
    Singleton() = default;
    ~Singleton() = default;
};
#endif//SINGLETON_IDIOM_SINGLETON_H