子类初始化列表不能初始化父类元素 -- class 'Derived' does not have any field named 'x'

缘由

偶尔编写如下代码，编译出错，

class Base{
   
public:
    int x;
};

class Derived : public Base {
   
public:
    Derived() : x(10) {
   
        cout << "Derived " << x << endl;
    };
    int y;
};

int main