error: non-binding let on a type that implements `Drop`
  --> $DIR/ice-5223.rs:14:9
   |
LL |         let _ = self.arr.iter().cloned().collect::<Vec<_>>();
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[deny(clippy::let_underscore_drop)]` on by default
   = help: consider using an underscore-prefixed named binding or dropping explicitly with `std::mem::drop`

error: aborting due to previous error