I feel like a sufficiently good debugger should allow you to place a breakpoint at any of the lines here, and it should break exactly at that specific line.

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

It sounds to me like you're asking for linebreaks. Chaining doesn't seem to be the issue here.