error: the following explicit lifetimes could be elided: 'a
  --> $DIR/ice-2774.rs:15:1
   |
LL | pub fn add_barfoos_to_foos<'a>(bars: &HashSet<&'a Bar>) {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `-D clippy::needless-lifetimes` implied by `-D warnings`

error: aborting due to previous error