error[E0505]: cannot move out of `a` because it is borrowed
  --> $DIR/borrow-for-loop-head.rs:4:18
   |
LL |     for i in &a {
   |              -- borrow of `a` occurs here
LL |         for j in a {
   |                  ^ move out of `a` occurs here

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 {
LL |         for j in a {
   |                  ^
   |                  |
   |                  `a` moved due to this implicit call to `.into_iter()`, in previous iteration of loop
   |                  help: consider borrowing to avoid moving into the for loop: `&a`
   |
note: this function consumes the receiver `self` by taking ownership of it, which moves `a`
  --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
   |
LL |     fn into_iter(self) -> Self::IntoIter;
   |                  ^^^^

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0382, E0505.
For more information about an error, try `rustc --explain E0382`.