error[E0597]: `r` does not live long enough
 --> $DIR/drop_reader_while_borrowed.rs:7:9
  |
5 |     let _s = {
  |         -- borrow later stored here
6 |         let mut r = Cursor::new("");
7 |         r.read_codepoint().unwrap()
  |         ^ borrowed value does not live long enough
8 |     };
  |     - `r` dropped here while still borrowed