vlib/v/checker/tests/chan_ref.vv:10:8: error: cannot push non-reference `St` on `chan &St`
    8 | fn f(ch chan &St, sem sync.Semaphore) {
    9 |     w := St{}
   10 |     ch <- w
      |           ^
   11 |     mut x := St{}
   12 |     ch <- x
vlib/v/checker/tests/chan_ref.vv:12:8: error: cannot push non-reference `St` on `chan &St`
   10 |     ch <- w
   11 |     mut x := St{}
   12 |     ch <- x
      |           ^
   13 |     // the following works
   14 |     y := &St{}
vlib/v/checker/tests/chan_ref.vv:28:11: error: cannot have a mutable reference to object from `chan &St`
   26 |     y := <-c
   27 |     // this should fail
   28 |     mut z := <-c
      |              ~~
   29 |     z.n = 9
   30 |     sem.post()
