c++ - Undo name hiding by "using" keyword. Does not work in grandchild class -

for example in below program undo name hiding "using" keyword. if have base , 1 derived class "im getting expected ambiguous call error". if have 2 derived class(child , grand child) child , grand child having same overloaded function here undo name hiding "using" keyword. getting compiled , got output. question why im not getting error "ambiguous call overloaded function".

class basenamehiding { protected: int namehidingexample(int t) {     cout<<"im baseeeeeeeeeeee"<<endl;     return 0; } }; class derivednamehiding:public basenamehiding {    public:     float namehidingexample(float s)     {         cout<<"im derived"<<endl;         return 0;     }     using basenamehiding::namehidingexample;  }; class grandderivednamehiding:public derivednamehiding { public:     float namehidingexample(float f)     {         cout<<"im grand derived"<<endl;         return 0;     }     using basenamehiding::namehidingexample;     using derivednamehiding::namehidingexample;  }; int main() {     char a;float f = 0.0;     derivednamehiding derived;     derived.namehidingexample(0);     grandderivednamehiding grandchild;     grandchild.namehidingexample(f);     cin>>a; }    //output im baseeeeeeeeeeee im grand derived 

you have encountered special rule of using-declarations. c++14 [namespace.udecl]/15:

when using-declaration brings names base class derived class scope, member functions , member function templates in derived class override and/or hide member functions , member function templates same name, parameter-type-list, cv-qualification, , ref-qualifier (if any) in base class (rather conflicting). [...] [ example:

struct b {     virtual void f(int);     virtual void f(char);     void g(int);     void h(int); };  struct d : b {     using b::f;     void f(int);    // ok: d::f(int) overrides b::f(int);      using b::g;     void g(char);   // ok      using b::h;     void h(int);    // ok: d::h(int) hides b::h(int) };  void k(d* p) {     p->f(1);        // calls d::f(int)     p->f(’a’);      // calls b::f(char)     p->g(1);        // calls b::g(int)     p->g(’a’);      // calls d::g(char) } 

— end example ]