1 error[E0499]: cannot borrow `b` as mutable more than once at a time
2 --> $DIR/mut-cant-alias.rs:9:20
5 | - first mutable borrow occurs here
7 | ^ second mutable borrow occurs here
9 | -- first borrow later used here
11 error: aborting due to previous error
13 For more information about this error, try `rustc --explain E0499`.