This is a real bug from the DIL compiler:

struct Foo
{
    enum
    {
        One,
    }
}

struct Bar
{
    alias Foo F;
    alias F.One First;  // alias Foo.One First; would work
}

void main()
{}

test.d(14): Error: alias test.Bar.First cannot alias an expression 0

What's interesting is that this compiles fine in DMD1.