error: reached the recursion limit while instantiating `rec::<&mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut &mut std::option::IntoIter<()>>`
  --> $DIR/recursion-issue-117696-2.rs:11:9
   |
LL |         rec(&mut it);
   |         ^^^^^^^^^^^^
   |
note: `rec` defined here
  --> $DIR/recursion-issue-117696-2.rs:7:1
   |
LL | fn rec<T: Iterator>(mut it: T) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 1 previous error