The current wording is not clear how to declare that a nested class template of a class template is a friend of its containing template. For example, is

  template <class T> struct C {
    template <bool b> class Foo;
    template <bool b> friend class Foo;
  }; 

correct, or should it be

  template <class T> struct C {
    template <bool b> class Foo;
    template <class X> template <bool b> friend class C<X>::Foo;
  };