[N1065 issue 1.19] An explicit specialization declaration may not be visible during instantiation under the template compilation model rules, even though its existence must be known to perform the instantiation correctly. For example:

translation unit #1

      template<class T> struct A { };
      export template<class T> void f(T) { A<T> a; }

      template<class T> struct A { };
      template<> struct A<int> { }; // not visible during instantiation
      template<class T> void f(T);
      void g() { f(1); }