No puedo ver por qué la declaración en main es ambigua.

template<class T, class U, int I> struct X
{ void f() { cout << "Primary template" << endl; } };


template<class T, int I> struct X<T, T*, I>
{void f() { cout << "Partial specialization 1" << endl;}};

template<class T, class U, int I> struct X<T*, U, I>
{void f() { cout << "Partial specialization 2" << endl;}};

template<class T> struct X<int, T*, 10>
{void f() { cout << "Partial specialization 3" << endl;}};

template<class T, class U, int I> struct X<T, U*, I>
{void f() { cout << "Partial specialization 4" << endl;}};

 int main()
 {
   X<int, int*, 10> f;
 }

No esX<int, T*, 10> la plantilla más especializada? Este es un ejemplo dehttp: //publib.boulder.ibm.com/infocenter/lnxpcomp/v8v101/index.jsp? topic =% 2Fcom.ibm.xlcpp8l.doc% 2Flanguage% 2Fref% 2Fpartial_specialization.htm