Is this legal?

[red floyd]

class A {
public:
  enum E { EN1, EN2, EN3 };
};

class B {
public:
    void f(const char *s, A::E en = A::E::EN1);
};

MSVC 7.1 accepts it, G++ 3.2.2 (3.2.2-3mdk) gives the following error:
`A::E' is not an aggregate type

Is this an error in G++ or in VC?  What does the Holy Standard say?