Rationale (August, 2011):

The specification is as intended. To the extent that there is an issue here, it is covered by issue 1172.

With the resolution of issue 1170, which takes access into account in template argument deduction, it is now possible to have instantiation-dependent expressions (see issue 1172) that do not directly involve a template parameter. For example:

  template <class T> struct C;

  class A
  {
    int i;
    friend struct C<int>;
  } a;

  class B
  {
    int i;
    friend struct C<float>;
  } b;

  template <class T>
  struct C
  {
    template <class U> decltype (a.i) f() { } // #1
    template <class U> decltype (b.i) f() { } // #2
  };

  int main()
  {
    C<int>().f<int>();   // calls #1
    C<float>().f<float>(); // calls #2
  }