temp.rs

fn encode_spans(rx : CollectorRx) -> impl Iterator<Item = spanpb::Span> {
    let finished_spans = rx.collect();
    let spans = finished_spans.into_iter().map(|span| {
        let mut s = spanpb::Span::default();

        s.set_id(span.id.into());
        s.set_start(span.elapsed_start);
        s.set_end(span.elapsed_end);
        s.set_event_id(span.tag);

        #[cfg(feature = "prost-codec")]
        if let Some(p) = span.parent {
            s.parent = Some(spanpb::Parent::ParentValue(p.into()));
        } else {
            s.parent = Some(spanpb::Parent::ParentNone(true));
        };
        #[cfg(feature = "protobuf-codec")]
        if let Some(p) = span.parent {
            s.set_parent_value(p.into());
        }
        s
    });
    spans.collect()
}

------
➜  tikv git:(minitrace) ✗ cargo check
    Checking tikv_util v0.1.0 (/Users/renkai/renkai-lab/tikv/components/tikv_util)
warning: unused import: `Span`
 --> components/tikv_util/src/trace.rs:1:30
  |
1 | use minitrace::{CollectorRx, Span};
  |                              ^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

error[E0277]: a value of type `impl std::iter::Iterator` cannot be built from an iterator over elements of type `kvproto::protos::span::Span`
  --> components/tikv_util/src/trace.rs:39:11
   |
39 |     spans.collect()
   |           ^^^^^^^ value of type `impl std::iter::Iterator` cannot be built from `std::iter::Iterator<Item=kvproto::protos::span::Span>`
   |
   = help: the trait `std::iter::FromIterator<kvproto::protos::span::Span>` is not implemented for `impl std::iter::Iterator`

error[E0720]: opaque type expands to a recursive type
  --> components/tikv_util/src/trace.rs:17:38
   |
17 | fn encode_spans(rx : CollectorRx) -> impl Iterator<Item = spanpb::Span> {
   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expands to a recursive type
   |
   = note: type resolves to itself

error: aborting due to 2 previous errors; 1 warning emitted

Some errors have detailed explanations: E0277, E0720.
For more information about an error, try `rustc --explain E0277`.
error: could not compile `tikv_util`.

To learn more, run the command again with --verbose.