rustfmt-nightly 1.0.1

mod m {
    struct S
    where
        A: B;
}

mod n {
    struct Foo
    where
        A: B,
    {
        foo: usize,
    }
}

mod o {
    enum Bar
    where
        A: B,
    {
        Bar,
    }
}

mod with_comments {
    mod m {
        struct S
        /* before where */
        where
            A: B; /* after where */
    }

    mod n {
        struct Foo
        /* before where */
        where
            A: B, /* after where */
        {
            foo: usize,
        }
    }

    mod o {
        enum Bar
        /* before where */
        where
            A: B, /* after where */
        {
            Bar,
        }
    }
}