Stream: wg-async-foundations

Topic: unclear issue triage


centril (Jun 25 2019 at 17:27, on Zulip):

We have https://github.com/rust-lang/rust/issues?q=is%3Aopen+is%3Aissue+label%3AAsyncAwait-Unclear

nikomatsakis (Jun 25 2019 at 17:28, on Zulip):

Ah yes. We should probably go over those next time -- or maybe a bit async

nikomatsakis (Jun 25 2019 at 17:28, on Zulip):

I'll start off a topic?

centril (Jun 25 2019 at 17:28, on Zulip):

https://github.com/rust-lang/rust/issues/61798 feels like something @varkor could have a look at

nikomatsakis (Jun 25 2019 at 17:29, on Zulip):

Potentially, yes. I can sort of imagine how this happens

nikomatsakis (Jun 25 2019 at 17:29, on Zulip):

there is probably some stuff in the desugaring that follows the await

nikomatsakis (Jun 25 2019 at 17:29, on Zulip):

which (indeed) is dead code

centril (Jun 25 2019 at 17:29, on Zulip):

probably something wrong with uninhabited analysis going on in the desugaring which doesn't care about await

nikomatsakis (Jun 25 2019 at 17:29, on Zulip):

we could probably suppress the lint by looking at the sppan

centril (Jun 25 2019 at 17:30, on Zulip):

yeah that seems like a good idea

nikomatsakis (Jun 25 2019 at 17:30, on Zulip):

but we'd have to be a bit careful

nikomatsakis (Jun 25 2019 at 17:30, on Zulip):

i.e., you want return; foo.await; to still lint :)

nikomatsakis (Jun 25 2019 at 17:30, on Zulip):

seems like a decent mentoring opportunity, too

nikomatsakis (Jun 25 2019 at 17:32, on Zulip):

I do not consider this blocking

centril (Jun 25 2019 at 17:32, on Zulip):

Yeah, seems marginal

nikomatsakis (Jun 25 2019 at 17:33, on Zulip):

Broken MIR: generator contains type std::vec::Vec<()> #62025

nikomatsakis (Jun 25 2019 at 17:35, on Zulip):

maybe a dup of the other ICEs...

centril (Jun 25 2019 at 17:35, on Zulip):

aww; that one in particular has the disadvantage of dependencies

centril (Jun 25 2019 at 17:35, on Zulip):

would have easily reduced the thing otherwise

centril (Jun 25 2019 at 17:35, on Zulip):

in the playground

centril (Jun 25 2019 at 17:40, on Zulip):

@nikomatsakis does https://github.com/rust-lang/rust/issues/61949 get addressed by your PR perhaps?

centril (Jun 25 2019 at 17:44, on Zulip):

That issue seems like it can have forward compat hazards since if you return x: Foo<'static> instead and the compiler accepts it now, and we change the return type to Foo<'a> then if Foo is contra/invariant wrt. the lifetime parameter then it shouldn't borrowck...?

nikomatsakis (Jun 25 2019 at 18:16, on Zulip):

I hadn't seen that issue before -- I don't think it's addressed by my PR per se. If I understand what's going on, seems like it is indeed a dup of https://github.com/rust-lang/rust/issues/53613 (and hence orthogonal to async-await). You may be correct that a fix could be a breaking change.

Last update: Nov 18 2019 at 01:40UTC