The following code won't compile:

    interface J(T) {}

    class A : J!(int) {}

    void foo(T)(J!(T) j) {}

    void main()
    {
       A a = new A;
       foo(a);
    }

The error is:
foo(T) does not match any function template declaration.

And yet it does. Change main to

    void main()
    {
       A a = new A;
       foo(cast(J!(int))a);
    }

and it compiles just fine. I contend that the explicit cast should not be necessary.