document the stabilized surface of async-await

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The Rust Reference

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document the stabilized surface of async-await #634

Open nikomatsakis opened 5 years ago

nikomatsakis commented 5 years ago

This issue is part of async-await stabilization (see https://github.com/rust-lang/rust/issues/62149). We need to document the following things:

[x] grammar for async fn and describe their effects
[x] grammar for async move { } blocks
[x] grammar for await expressions, and describe the "rough" desugaring
[ ] link to the drop order when that is fully documented

nikomatsakis commented 5 years ago

I am taking a first pass at this.

alercah commented 4 years ago

Async closures are missing.

nikomatsakis commented 4 years ago

Async closures are not stabilized, and this issue was specific to stabilized surface area -- actually, I think we can probably close this? I'm not sure what I meant by 'document the drop order'.

nikomatsakis commented 4 years ago

@cramertj or @withoutboats do you have any idea what I might have meant by "link to drop order when that is stabilized"?

I do know that @matthewjasper recently opened a PR about https://github.com/rust-lang/reference/pull/514 drop scopes which I think mentioned something about drop order here...

alercah commented 4 years ago

They're not stabilized? Why does https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=3795067a2d54b2d90a5d807eed51a93e work then?

On Thu., Apr. 16, 2020, 12:32 Niko Matsakis, notifications@github.com wrote:

@cramertj https://github.com/cramertj or @withoutboats https://github.com/withoutboats do you have any idea what I might have meant by "link to drop order when that is stabilized"?

I do know that @matthewjasper https://github.com/matthewjasper recently opened a PR about #514 https://github.com/rust-lang/reference/pull/514 drop scopes which I think mentioned something about drop order here...

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cramertj commented 4 years ago

I would guess the drop order bit has to do with the changes we made around when _ arguments to async functions get dropped.

kpreid commented 1 month ago

Another thing that is currently undocumented is async block/fn future types, as types. I filed #1555 for that.