//# publish
module 0x1.Tester {
    struct X { f: u64 }

    bump_and_give(x_ref: &mut Self.X): &u64 {
    label b0:
        *(&mut copy(x_ref).X::f) = *&mut copy(x_ref).X::f + 1;
        return &move(x_ref).X::f;
    }

    contrived_example(x_ref: &mut Self.X): &u64 {
        let returned_ref: &u64;
    label b0:
        returned_ref = Self.bump_and_give(copy(x_ref));
        // it is valid to immutably extend the reference
        // even though a mut extension + freeze would be invalid
        assert(*copy(returned_ref) == *&move(x_ref).X::f, 42);
        return move(returned_ref);
    }
}