error[E0596]: cannot borrow data in a `&` reference as mutable
  --> $DIR/dont-print-desugared.rs:4:10
   |
LL |     for &ref mut x in s {}
   |         -^^^^^^^^^
   |         ||
   |         |cannot borrow as mutable through `&` reference
   |         help: consider changing this to be a mutable reference: `&mut ref mut x`

error[E0597]: `y` does not live long enough
  --> $DIR/dont-print-desugared.rs:17:16
   |
LL |     for ref mut d in v {
   |                      - a temporary with access to the borrow is created here ...
LL |         let y = ();
LL |         *d = D(&y);
   |                ^^ borrowed value does not live long enough
LL |     }
   |     -
   |     |
   |     `y` dropped here while still borrowed
   |     ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `D`

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0596, E0597.
For more information about an error, try `rustc --explain E0596`.