1    private@
2    
3    type A @byval =
4        val ptr : Ptr<i32>
5    
6    type B @byval =
7        val ptr : MutPtr<i32> @impl
8    
9        inherit A
10   
11   do
12       let mut x = 7
13       let b = B x@mut_ptr
14       assert b.ptr == x@mut_ptr
15       assert sizeof B == sizeof Ptr<i32>
16