C++ Return Secret

Demo1.cpp

#include <iostream>
struct foo
{
        static int count;
        int id;
        foo() : id(++count)
        {
                std::cout << "Constructing! " << id << std::endl;
        }

        foo(const foo& f) :id(++count)
        {
                std::cout << "Copy constructing! " << id << std::endl;
        }

        ~foo()
        {
                std::cout << "Destructing.. " << id << std::endl;
        }
};
int foo::count = 0;
foo get()
{
        foo f;
        return f;
}
int main()
{
        foo f = get();
        std::cout << "before return" << std::endl;
        return 0;
}

Demo2.cpp

#include <iostream>
struct foo
{
        static int count;
        int id;
        foo() : id(++count)
        {
                std::cout << "Constructing! " << id << std::endl;
        }

        foo(const foo& f) :id(++count)
        {
                std::cout << "Copy constructing! " << id << std::endl;
        }

        ~foo()
        {
                std::cout << "Destructing.. " << id << std::endl;
        }
};
int foo::count = 0;
foo get()
{
        foo f;
        return f;
}
int main()
{
        const foo& f = get();
        std::cout << "before return" << std::endl;
        return 0;
}