vlib/v/checker/tests/mut_assign_ref.vv:10:12: error: `f` is immutable, cannot have a mutable reference to it
    8 | fn main() {
    9 |     f := Foo{}
   10 |     mut pf := &f
      |               ^
   11 |     pf = &f
   12 |     p := &f
vlib/v/checker/tests/mut_assign_ref.vv:11:7: error: `f` is immutable, cannot have a mutable reference to it
    9 |     f := Foo{}
   10 |     mut pf := &f
   11 |     pf = &f
      |          ^
   12 |     p := &f
   13 |     _ = p
vlib/v/checker/tests/mut_assign_ref.vv:15:11: error: `constant` is immutable, cannot have a mutable reference to it
   13 |     _ = p
   14 | 
   15 |     mut c := &constant
      |              ^
   16 |     c.value = 200
   17 |     c = &constant
vlib/v/checker/tests/mut_assign_ref.vv:17:6: error: `constant` is immutable, cannot have a mutable reference to it
   15 |     mut c := &constant
   16 |     c.value = 200
   17 |     c = &constant
      |         ^
   18 |     ic := &constant // ok
   19 |     _=ic
