---
title: WG-async triage meeting 2024-04-08
tags: ["WG-async", "triage-meeting", "minutes"]
date: 2024-04-08
discussion: https://rust-lang.zulipchat.com/#narrow/stream/187312-wg-async/topic/Triage.20meeting.202024-04-08
url: https://hackmd.io/xlZGjBqXS6iqQ7qHpccm1w
---

# WG-async meeting agenda

- Meeting date: 2024-04-08

## Attendance

- People: TC, Yosh, Daria

## Meeting roles

- Minutes: TC

## Scheduled meetings

None.

Update these [here](https://github.com/orgs/rust-lang/projects/40/views/1).

## Proposed meetings

None.

Update these [here](https://github.com/orgs/rust-lang/projects/40/views/1).

## Announcements or custom items

(Meeting attendees, feel free to add items here!)

## Untriaged issues

### "Recursive async functions don't internally implement auto traits" rust#123072

**Link:** https://github.com/rust-lang/rust/issues/123072

We left a comment.

### "Async closures are not allowed to reference all captured lifetimes if one of them is invariant" rust#123241

**Link:** https://github.com/rust-lang/rust/issues/123241

We left a comment.

### "Incorrect line table generation for await points" rust#123341

**Link:** https://github.com/rust-lang/rust/issues/123341

We left a comment.

### "Add LocalWaker support" libs-team#191

**Link:** https://github.com/rust-lang/libs-team/issues/191

We left a comment and unnominated this. There's a checkbox on the tracking issue for checking that WG-async is OK with the design prior to stabilization.

### "Context reactor hook" libs-team#347

**Link:** https://github.com/rust-lang/libs-team/issues/347

Yosh: I feel like this design wouldn't work for the executor I'm writing. Or if it would, it would not be ergonomic. I should sit down with Justin and dig into this. Then we would know for sure, and maybe some small change would address this.

TC: Let's leave this nominated, as there does seem more for us to discuss here.

Daria: Seems to be incompatible with [wasm-bindgen-futures](https://crates.io/crates/wasm-bindgen-futures)

Yosh: yes, that makes sense.

## Discussion about `AsyncIterator`

(Various discussion.)

TC: So we'd have `async gen` blocks return an opaque type that implements `IntoAsyncGen`...

TC/Yosh:

trait AsyncGen: Future<Output = Option<Self::Item>> {
    type Item;
}

trait IntoAsyncGen {
    type Item;
    type IntoAsyncGen: AsyncGen<Item = Self::Item>;
    fn into_async_gen(self) -> Self::IntoAsyncGen;
}

struct Foo;
impl IntoAsyncGen for Pin<&mut Foo> {
    async gen fn into_async_gen(self) -> _ {
        todo!()
    }
}

//trait AsyncIterator { async fn next(); }

async fn main() {
    let x: impl IntoAsyncGen = async gen {};
}

TC: Object safety:

trait AsyncIterator {
    type Item;
    async fn next(&mut self) -> Self::Item;
}

TC/Yosh:

// AFIT, state is split between self and `next`
trait AsyncIterator {
    type Item;
    type Next<'a>: Future<Output = Self::Item> where Self: 'a;
    fn next(&mut self) -> Self:Next<'_>;
}

// sync, state is split between self and `next`
trait Iterator {
    fn next(&mut self)  { ... /* local state */ }
}

// all state lives in self
trait AsyncIterator {
    type Item;
    fn poll_next(self: Pin<..>) -> Poll<...> {}
}

trait AsyncGen: Future<Output = Option<Self::Thing>> {
    ..
}

coro fn handler(mut x: Input) yields Output {
    loop {
        x = yield do_something_with_input(x);
    }
}

(The meeting ended here.)

## Nominated RFCs, PRs, and issues

### "Tracking Issue for `waker_getters`" rust#96992

**Link:** https://github.com/rust-lang/rust/issues/96992

### "Tracking Issue for `task::Waker::noop`" rust#98286

**Link:** https://github.com/rust-lang/rust/issues/98286

### "Tracking Issue for `Ready::into_inner()`" rust#101196

**Link:** https://github.com/rust-lang/rust/issues/101196

### "Tracking Issue for `const_waker`" rust#102012

**Link:** https://github.com/rust-lang/rust/issues/102012

### "Rename `AsyncIterator` back to `Stream`, introduce an AFIT-based `AsyncIterator` trait" rust#119550

**Link:** https://github.com/rust-lang/rust/pull/119550

### "Clarification needed on what happens when `Future::poll` wakes an old waker" rust#119698

**Link:** https://github.com/rust-lang/rust/issues/119698

### "Add LocalWaker support" libs-team#191

**Link:** https://github.com/rust-lang/libs-team/issues/191

### "Context reactor hook" libs-team#347

**Link:** https://github.com/rust-lang/libs-team/issues/347

## WG RFCs, PRs, and issues nominated for T-lang/T-types

### "Initial support for auto traits with default bounds" rust#120706

**Link:** https://github.com/rust-lang/rust/pull/120706

### "Add simple async drop glue generation" rust#121801

**Link:** https://github.com/rust-lang/rust/pull/121801

## Pending PRs on the WG-async repo

None.

## `S-waiting-on-team`

### "Rename `AsyncIterator` back to `Stream`, introduce an AFIT-based `AsyncIterator` trait" rust#119550

**Link:** https://github.com/rust-lang/rust/pull/119550

## Proposed FCPs

**Check your boxes!**

### "Tracking Issue for `Ready::into_inner()`" rust#101196

**Link:** https://github.com/rust-lang/rust/issues/101196

### "Tracking Issue for `const_waker`" rust#102012

**Link:** https://github.com/rust-lang/rust/issues/102012

## Active FCPs

None.

## P-critical issues

None.

## WG-async work project board

https://github.com/orgs/rust-lang/projects/29/views1/d