|  | error[E0505]: cannot move out of `a` because it is borrowed | 
|  | --> $DIR/borrow-for-loop-head.rs:4:18 | 
|  | | | 
|  | LL |     let a = vec![1, 2, 3]; | 
|  | |         - binding `a` declared here | 
|  | LL |     for i in &a { | 
|  | |              -- borrow of `a` occurs here | 
|  | LL |         for j in a { | 
|  | |                  ^ move out of `a` occurs here | 
|  | | | 
|  | help: consider cloning the value if the performance cost is acceptable | 
|  | | | 
|  | LL |     for i in &a.clone() { | 
|  | |                ++++++++ | 
|  |  | 
|  | error[E0382]: use of moved value: `a` | 
|  | --> $DIR/borrow-for-loop-head.rs:4:18 | 
|  | | | 
|  | LL |     let a = vec![1, 2, 3]; | 
|  | |         - move occurs because `a` has type `Vec<i32>`, which does not implement the `Copy` trait | 
|  | LL |     for i in &a { | 
|  | |     ----------- inside of this loop | 
|  | LL |         for j in a { | 
|  | |                  ^ `a` moved due to this implicit call to `.into_iter()`, in previous iteration of loop | 
|  | | | 
|  | note: `into_iter` takes ownership of the receiver `self`, which moves `a` | 
|  | --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL | 
|  | help: consider iterating over a slice of the `Vec<i32>`'s content to avoid moving into the `for` loop | 
|  | | | 
|  | LL |         for j in &a { | 
|  | |                  + | 
|  |  | 
|  | error: aborting due to 2 previous errors | 
|  |  | 
|  | Some errors have detailed explanations: E0382, E0505. | 
|  | For more information about an error, try `rustc --explain E0382`. |