error[E0521]: borrowed data escapes outside of function
  --> $DIR/trait-objects.rs:15:5
   |
LL | fn min_size(x: &mut dyn for<'a> StreamingIterator<Item<'a> = &'a i32>) -> usize {
   |             -  - let's call the lifetime of this reference `'1`
   |             |
   |             `x` is a reference that is only valid in the function body
LL |
LL |     x.size_hint().0
   |     ^^^^^^^^^^^^^
   |     |
   |     `x` escapes the function body here
   |     argument requires that `'1` must outlive `'static`
   |
   = note: due to current limitations in the borrow checker, this implies a `'static` lifetime

error: aborting due to previous error

For more information about this error, try `rustc --explain E0521`.