error[E0499]: cannot borrow `i` as mutable more than once at a time --> $DIR/E0499.rs:4:17 | LL | let mut x = &mut i; | ------ first mutable borrow occurs here LL | let mut a = &mut i; | ^^^^^^ second mutable borrow occurs here LL | a.use_mut(); LL | x.use_mut(); | ----------- first borrow later used here error: aborting due to previous error For more information about this error, try `rustc --explain E0499`.