> It doesn't allow you to import `std::iter::Iterator::collect` on its own. It's an associated function, and needs to be qualified.

You probably noticed, but it should become a thing in RFC 3591: https://github.com/rust-lang/rust/issues/134691

So it does kind of work on current nightly:

  #![feature(import_trait_associated_functions)]
  
  use std::iter::Iterator::{filter, map, collect};

  fn get_ids2(data: Vec<Widget>) -> Vec<Id> {
      collect(map(filter(Vec::into_iter(data), |w| w.alive), |w| w.id))
  }  

  fn get_ids3(data: impl Iterator<Item = Widget>) -> Vec<Id> {
      collect(map(filter(data, |w| w.alive), |w| w.id))
  }