error[E0499]: cannot borrow `v` as mutable more than once at a time --> $DIR/borrowck-vec-pattern-loan-from-mut.rs:6:13 | LL | let vb: &mut [isize] = &mut v; | ------ first mutable borrow occurs here ... LL | v.push(tail[0] + tail[1]); | ^ ------- first borrow later used here | | | second mutable borrow occurs here error: aborting due to previous error For more information about this error, try `rustc --explain E0499`.