Stream: t-compiler/wg-nll

Topic: #58776 migrate mode erroneously downgrades error from chi...


lqd (Feb 27 2019 at 13:00, on Zulip):

@Matthew Jasper @pnkfelix does this remind you of an existing issue we might have or is this new ? @RalfJ brought it up in another context and the gist is: this UB doesn't build with AST borrowck, nor with NLLs, but migrate mode downgrades the errors to warnings here

lqd (Feb 27 2019 at 13:02, on Zulip):

(use the "Build" action thingy on the playground, if it runs, there's likely going to be invalid utf-8 printed, hiding the warnings, because of output like "Execution operation failed: Output was not valid UTF-8: invalid utf-8 sequence of 1 bytes from index 17")

centril (Feb 27 2019 at 13:03, on Zulip):

(you have to try a few times before you get output)

lqd (Feb 27 2019 at 13:03, on Zulip):

yeah that's why I mentioned to just build and not run

lqd (Feb 27 2019 at 13:05, on Zulip):

(and not segfault the playground or anything :)

lqd (Feb 27 2019 at 13:06, on Zulip):

poor shep probably being pinged in the middle of the night about crashes ;)

Matthew Jasper (Feb 27 2019 at 13:06, on Zulip):

We've had a similar issue in the past, but the fix for it didn't address this case, presumably because we lacked an example.

lqd (Feb 27 2019 at 13:07, on Zulip):

definitely feels familiar ya

Matthew Jasper (Feb 27 2019 at 13:07, on Zulip):

That case was NLL reports an error on the closure and AST reports it on the parent. Here we have it the other way around.

Matthew Jasper (Feb 27 2019 at 13:08, on Zulip):

You can see the current fix at borrow_check/mod.rs:347

lqd (Feb 27 2019 at 13:09, on Zulip):

ah yes

lqd (Feb 27 2019 at 13:10, on Zulip):

the old issue being #55492

lqd (Feb 27 2019 at 13:13, on Zulip):

so I'm guessing we might not have an issue for this yet, maybe Felix knows more. I'll poke at it during lunchbreak, and create the issue if we don't hav one; could be interesting to nominate it for tonight's meeting

pnkfelix (Feb 27 2019 at 13:19, on Zulip):

I don't think we have any issue filed about this

pnkfelix (Feb 27 2019 at 13:19, on Zulip):

and it definitely looks worth attacking

pnkfelix (Feb 27 2019 at 13:20, on Zulip):

well

pnkfelix (Feb 27 2019 at 13:20, on Zulip):

maybe I'm overstating the priority.

pnkfelix (Feb 27 2019 at 13:22, on Zulip):

okay and I see that this came from an issue @RalfJ filed, #58776

lqd (Feb 27 2019 at 13:23, on Zulip):

ah I didn't see ralf had filed it in the meantime

lqd (Feb 27 2019 at 13:23, on Zulip):

I started looking at it earlier, sorry for the noise

pnkfelix (Feb 27 2019 at 13:26, on Zulip):

not noise at all. its good to be aware of this. (We would have discussed it tonight since @Matthew Jasper nominated it, but still)

Matthew Jasper (Feb 27 2019 at 13:28, on Zulip):

It was nominated by jonas-schievink ( I don't know if they're here).

pnkfelix (Feb 27 2019 at 13:32, on Zulip):

oh my mistake. but in any case, it implies we should discuss it tonight. :smile:

RalfJ (Feb 27 2019 at 14:16, on Zulip):

this UB doesn't build with AST borrowck, nor with NLLs, but migrate mode downgrades the errors to warnings here

Hm, when I try feature(nll) playground times out...

RalfJ (Feb 27 2019 at 14:17, on Zulip):

ah no it was just slow, never mind

Last update: Nov 22 2019 at 00:10UTC