unit p where
    signature H where
        data H = H
    module A where
        import H
        data A = A H

unit q where
    module H where
        data S = S

unit r where
    dependency p[H=q:H]
    -- This test passes if r is definite, because we'll
    -- first try to compile p.  Key is to make r indefinite!
    signature H2 where
    module B where
        import A
        x = A H