Why copy elision not working with std::move?

I use the code below to test copy elision:

class foo
{
public:
    foo() {cout<<"ctor"<<endl;};
    foo(const foo &rhs) {cout<<"copy ctor"<<endl;}
};

int g(foo a)
{
    return 0;
}

int main()
{
    foo a;
    g(std::move(a));
    return 0;
}

I expected only the default constructor would be called because the argument of g() is an rvalue and copy will be elided. But the result shows that both the default constructor and the copy constructor are called. Why?

And if I change the function call to g(foo()), the copy will be elided. What's the difference between the return types of foo() and std::move(a)? How can I make the compiler elide copy on an lvalue?