currently you can't have opDispatch resolve to a non-member template:

//break.d
struct A
{    
    template opDispatch(string s)
    {
        mixin("alias opDispatch = " ~ s ~ ";");
    }
}

struct B()
{
    enum blah = 42;
}

unittest
{
    alias Q = A.B!();
    pragma(msg, Q.blah);
}

$ rdmd -unittest break.d
break.d(1): Error: struct f477.A template identifier 'B' is not a member of 'struct A'
break.d(1): Error: struct f477.A template identifier 'B' is not a member of 'struct A'
42


As you can see, the code works, 42 is the answer! Unfortunately there's the error...

note: I'm not sure whether this is a bug report or an enhancement request, as I don't know what the current design is supposed to allow.