error[E0499]: cannot borrow `foo[_]` as mutable more than once at a time --> $DIR/suggest-split-at-mut.rs:4:13 | LL | let a = &mut foo[2]; | ----------- first mutable borrow occurs here LL | let b = &mut foo[3]; | ^^^^^^^^^^^ second mutable borrow occurs here LL | *a = 5; | ------ first borrow later used here | = help: consider using `.split_at_mut(position)` or similar method to obtain two mutable non-overlapping sub-slices = help: consider using `.swap(index_1, index_2)` to swap elements at the specified indices error: aborting due to previous error For more information about this error, try `rustc --explain E0499`.