1error[E0499]: cannot borrow `v` as mutable more than once at a time 2 --> $DIR/one_line.rs:3:12 3 | 4LL | v.push(v.pop().unwrap()); 5 | -------^^^^^^^---------- 6 | | | | 7 | | | second mutable borrow occurs here 8 | | first borrow later used by call 9 | first mutable borrow occurs here 10 11error: aborting due to previous error 12 13For more information about this error, try `rustc --explain E0499`. 14