error[E0626]: borrow may still be in use when generator yields
  --> $DIR/yield-while-iterating.rs:22:19
   |
22 |         for p in &x { //~ ERROR
   |                   ^
23 |             yield();
   |             ------- possible yield occurs here

error[E0502]: cannot borrow `x` as immutable because it is also borrowed as mutable
  --> $DIR/yield-while-iterating.rs:67:20
   |
62 |     let mut b = || {
   |                 -- mutable borrow occurs here
63 |         for p in &mut x {
   |                       - previous borrow occurs due to use of `x` in closure
...
67 |     println!("{}", x[0]); //~ ERROR
   |                    ^ immutable borrow occurs here
68 |     b.resume();
69 | }
   | - mutable borrow ends here

error: aborting due to 2 previous errors