C++ philosophy: Changing the accessibility of a class member should never change the meaning of a program.

#include <iostream>
using std::cout;
using std::endl;
class Base1{
public:
       void foo(){cout<< "Base1::foo"<<endl;};
};

class Base2{
private:
       void foo(){cout<< "Base1::foo"<<endl;};
};

class Dirived : public Base1,public Base2{};

int main(){
      Dirived d;
      d.foo();
      return 0;
}

d.foo();这一行编译器会报错 error: "Dirived::foo" is ambiguous

那么既然，Bas2的foo是一个私有函数，在Dirived类中并不可见，为什么编译器还傻傻的说ambiguous呢?