@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
(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")
(you have to try a few times before you get output)
yeah that's why I mentioned to just build and not run
(and not segfault the playground or anything :)
poor shep probably being pinged in the middle of the night about crashes ;)
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.
definitely feels familiar ya
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.
You can see the current fix at borrow_check/mod.rs:347
the old issue being #55492
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
I don't think we have any issue filed about this
and it definitely looks worth attacking
maybe I'm overstating the priority.
okay and I see that this came from an issue @RalfJ filed, #58776
ah I didn't see ralf had filed it in the meantime
I started looking at it earlier, sorry for the noise
not noise at all. its good to be aware of this. (We would have discussed it tonight since @Matthew Jasper nominated it, but still)
It was nominated by jonas-schievink ( I don't know if they're here).
oh my mistake. but in any case, it implies we should discuss it tonight. :smile:
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...
ah no it was just slow, never mind