rvalue reference's illegal operations :     class A { int x; };
    int main() {
        A&& a=A(); // 1
        a.x=nullptr; // 2
        cout<<a.x<<endl; 
        cout<<&a<<endl; // 3
        return 0;
    }

Questions: (respectively with the numbers in each line)

1. Is there an implicit cast __from__ temporary values (values of built-in type, and temporary objects) __to__ objects of type `rvalue reference`?

2. I understood that the lifetime of a temporary object is ended after it's evaluation. If I am right, does it mean that `a.x=nullptr` is unsafe?

3. Does `a` has an address?