vlib/v/checker/tests/auto_deref_assign_err.vv:10:6: error: cannot assign to `o`: expected `&int`, not `string`
    8 | fn sub(mut o &int) {
    9 |     println('in function got: ' + o.str())
   10 |     o = 'mutate int as string??'
      |         ~~~~~~~~~~~~~~~~~~~~~~~~
   11 | }