If one instance of an overloaded function or operator is generic, I cannot
supply a member of an anonymous enum to that function or operator, even if I
wouldn't be calling the generic instance anyway.  As an example of the problem,
attempting to compile the simplified code

  class S;
  template <typename T> S& operator<< (S&, const T&);

  enum { x };
  static const int xx = 1 << x;

with G++ 4.0.0 fails with the error

anonenum.cc:5: error: '<anonymous enum>' is/uses anonymous type
anonenum.cc:5: error:   trying to instantiate 'template<class T> S&
operator<<(S&, const T&)'

This is a regression over previous versions, which have no problem with such
code.  (Neither do other vendors' compilers.)

It is obviously trivial to work around the bug by naming the enum, but I believe
I shouldn't need to.