Stream: t-compiler/meetings

Topic: [weekly meeting] 2020-09-03 #54818


Santiago Pastorino (Sep 02 2020 at 20:37, on Zulip):

Hi @T-compiler/meeting; the triage meeting will happen tomorrow at

Santiago Pastorino (Sep 02 2020 at 20:37, on Zulip):

The @WG-prioritization have done pre-triage in #t-compiler/wg-prioritization/alerts

Santiago Pastorino (Sep 02 2020 at 20:38, on Zulip):

@WG-prioritization have prepared the meeting agenda

Santiago Pastorino (Sep 02 2020 at 20:38, on Zulip):

We will have checkins from @WG-rustc-dev-guide and @WG-llvm

Santiago Pastorino (Sep 02 2020 at 20:39, on Zulip):

@mark-i-m do you want to give the checkin for @WG-rustc-dev-guide? otherwise I can try to provide something :) but I guess we don't have that much

Santiago Pastorino (Sep 02 2020 at 20:39, on Zulip):

@nagisa do you have something you want to share about @WG-llvm?

Santiago Pastorino (Sep 02 2020 at 20:46, on Zulip):

@T-compiler/meeting as always please feel free to nominate issues that are worth discussing or ones you want to see moving forward

Santiago Pastorino (Sep 02 2020 at 20:47, on Zulip):

if you do so, between today and tomorrow before the meeting, just in case let me know so I can add them to the agenda :)

Santiago Pastorino (Sep 02 2020 at 20:47, on Zulip):

I usually check stuff right before the meeting but pinging me won't hurt :)

nagisa (Sep 03 2020 at 12:22, on Zulip):

no updates from me, but its more like I didn’t spend too much time looking for things rather than there not being any activity.

Santiago Pastorino (Sep 03 2020 at 13:12, on Zulip):

I wonder if noticing leads about checkins with more time would help

Santiago Pastorino (Sep 03 2020 at 13:13, on Zulip):

to be honest, I'm also complicating myself because I need to build rustc-dev-guide checkin in a rush now :)

Santiago Pastorino (Sep 03 2020 at 13:13, on Zulip):

one thing that we've tried to do is to keep a document with the following checkin and update it as we go, but it often ends being outdated

Santiago Pastorino (Sep 03 2020 at 13:14, on Zulip):

anyway, if letting others know about checkins before would help, I can actually ping people right after a compiler meeting so everyone is aware 1 week in advance :)

Santiago Pastorino (Sep 03 2020 at 13:15, on Zulip):

Hi @T-compiler/meeting, triage meeting will be starting in ~ 45 minutes, at

Santiago Pastorino (Sep 03 2020 at 13:16, on Zulip):

Check out the meeting agenda

pnkfelix (Sep 03 2020 at 14:03, on Zulip):

Hi @T-compiler/meeting! Add a :wave: emoji to show you're here :)

pnkfelix (Sep 03 2020 at 14:03, on Zulip):

we will start off with 5 minutes for ...

Announcements

pnkfelix (Sep 03 2020 at 14:03, on Zulip):
pnkfelix (Sep 03 2020 at 14:04, on Zulip):

(and this time I'm going to remember to show up to the meeting!)

pnkfelix (Sep 03 2020 at 14:04, on Zulip):
pnkfelix (Sep 03 2020 at 14:04, on Zulip):
pnkfelix (Sep 03 2020 at 14:04, on Zulip):
pnkfelix (Sep 03 2020 at 14:05, on Zulip):
pnkfelix (Sep 03 2020 at 14:05, on Zulip):
pnkfelix (Sep 03 2020 at 14:05, on Zulip):
pnkfelix (Sep 03 2020 at 14:06, on Zulip):

WG checkins

@WG-rustc-dev-guide checkin by @Santiago Pastorino:

pnkfelix (Sep 03 2020 at 14:07, on Zulip):

/me assumes @_mark-i-am is the same as mark-i-m ?

pnkfelix (Sep 03 2020 at 14:07, on Zulip):

(anyway I'm also sorry to hear that mark is stepping back.)

Santiago Pastorino (Sep 03 2020 at 14:07, on Zulip):

yeah

Santiago Pastorino (Sep 03 2020 at 14:08, on Zulip):

that _ was a mistake when adding the checkin

pnkfelix (Sep 03 2020 at 14:08, on Zulip):

anyway let me post the rest of that wg-checkin

pnkfelix (Sep 03 2020 at 14:08, on Zulip):

(I was actually referring to the "am", not the underscore)

Santiago Pastorino (Sep 03 2020 at 14:08, on Zulip):

oh, right :), everything is wrong then :joy:

pnkfelix (Sep 03 2020 at 14:08, on Zulip):

rest of checkin:

Changes in progress

pnkfelix (Sep 03 2020 at 14:09, on Zulip):

@WG-llvm checkin by @nagisa

no updates from me, but its more like I didn’t spend too much time looking for things rather than there not being any activity.

Santiago Pastorino (Sep 03 2020 at 14:09, on Zulip):

another thing about the rustc-dev-guide wg, we would need to find another lead and also there's not a lot of working power lately

pnkfelix (Sep 03 2020 at 14:10, on Zulip):

oh that reminds me

pnkfelix (Sep 03 2020 at 14:10, on Zulip):
pnkfelix (Sep 03 2020 at 14:10, on Zulip):

(i've been hugely distracted by various childcare things for past month or so, but we found a nanny!)

pnkfelix (Sep 03 2020 at 14:11, on Zulip):

okay, so, on to rest of the meeting

pnkfelix (Sep 03 2020 at 14:11, on Zulip):

Beta-nominations

T-compiler

pnkfelix (Sep 03 2020 at 14:12, on Zulip):
simulacrum (Sep 03 2020 at 14:13, on Zulip):

There's some discussion on why this is not a stable-nom here, https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/.2376015.20beta.20nomination btw

pnkfelix (Sep 03 2020 at 14:13, on Zulip):

/me reflects for a bit about whether it was wrong to approve PR #72357. But I think this is a case where it is best to be willing to break things

simulacrum (Sep 03 2020 at 14:13, on Zulip):

but basically "Seems plausibly risky and no tests in-tree, really"

pnkfelix (Sep 03 2020 at 14:13, on Zulip):

(and then fix them afterwards)

pnkfelix (Sep 03 2020 at 14:14, on Zulip):

so I admit that I am a bit confused: We do have debugger tests in tree, right?

simulacrum (Sep 03 2020 at 14:14, on Zulip):

we do

pnkfelix (Sep 03 2020 at 14:14, on Zulip):

do those tests not use the wrapper scripts?

simulacrum (Sep 03 2020 at 14:14, on Zulip):

but frankly we test on a very limited suite of debuggers

simulacrum (Sep 03 2020 at 14:15, on Zulip):

(like, basically one version per platform)

pnkfelix (Sep 03 2020 at 14:15, on Zulip):

ah okay so that would make sense

Wesley Wiser (Sep 03 2020 at 14:15, on Zulip):

It sounds like things are already broken. This probably won't break them more, it just might not fix them.

pnkfelix (Sep 03 2020 at 14:15, on Zulip):

do we test lldb somewhere ? if so, where?

simulacrum (Sep 03 2020 at 14:15, on Zulip):

I think on macOS test builders

simulacrum (Sep 03 2020 at 14:15, on Zulip):

(but who knows, we've broken that testing and not noticed before)

simulacrum (Sep 03 2020 at 14:16, on Zulip):

@Wesley Wiser yeah, that's a good point

pnkfelix (Sep 03 2020 at 14:16, on Zulip):

hmm. #76006 claimed they observed the breakage on MacOS too

simulacrum (Sep 03 2020 at 14:16, on Zulip):

I'm comfortable with a beta backport for sure

pnkfelix (Sep 03 2020 at 14:16, on Zulip):

okay. I think a beta backport makes sense

Santiago Pastorino (Sep 03 2020 at 14:16, on Zulip):

Wesley Wiser said:

It sounds like things are already broken. This probably won't break them more, it just might not fix them.

with this reasoning, shouldn't we also backport for stable?

simulacrum (Sep 03 2020 at 14:16, on Zulip):

I don't feel this is significant enough for a stable point release personally, but maybe that's because I barely ever use gdb on Rust code

simulacrum (Sep 03 2020 at 14:16, on Zulip):

but I guess that's orthogonal

simulacrum (Sep 03 2020 at 14:17, on Zulip):

I would want it to bake for longer before stable-approving regardless

pnkfelix (Sep 03 2020 at 14:17, on Zulip):

a debugger is sometimes still the best option for certain kinds of tasks

Santiago Pastorino (Sep 03 2020 at 14:17, on Zulip):

simulacrum said:

I would want it to bake for longer before stable-approving regardless

you meant that this can live on beta for a bit and maybe in some weeks we can stable nominate? but for the following stable version?

pnkfelix (Sep 03 2020 at 14:17, on Zulip):

anyway lets say beta-approved then

Wesley Wiser (Sep 03 2020 at 14:18, on Zulip):

I'm not super familiar with lldb so I would be uncomfortable making the claim in a stable point release that this fixes something unless we had tests or some other way of proving it does fix the issue.

Wesley Wiser (Sep 03 2020 at 14:18, on Zulip):

But this seems fine for beta

simulacrum (Sep 03 2020 at 14:19, on Zulip):

I'd say we should move on

simulacrum (Sep 03 2020 at 14:19, on Zulip):

if someone feels strongly about a stable-nom feel free to nominate it for next meeting :)

pnkfelix (Sep 03 2020 at 14:19, on Zulip):

I also just filed "Why didnt our test suite catch lldb breakage?" #76288

pnkfelix (Sep 03 2020 at 14:19, on Zulip):

next up

pnkfelix (Sep 03 2020 at 14:19, on Zulip):
pnkfelix (Sep 03 2020 at 14:20, on Zulip):

I read the discussion here before the meeting. I'm inclined to let this ride the trains.

simulacrum (Sep 03 2020 at 14:20, on Zulip):

I feel mostly "shrug" about this, slightly inclined to say no.

pnkfelix (Sep 03 2020 at 14:21, on Zulip):

(It seemed like the person who nominated it just wasn't sure what our policy or maybe goals are with respect to backports, specifically whether to keep lints and features in sync.)

pnkfelix (Sep 03 2020 at 14:21, on Zulip):

if someone wants to argue for a backport, feel free to speak up during the rest of the meeting (or PM me before the end) and we can circle back to it.

pnkfelix (Sep 03 2020 at 14:22, on Zulip):

but I'm going to assume "declining to beta-backport" until such event occurs.

pnkfelix (Sep 03 2020 at 14:22, on Zulip):

libs-impl

T-rustdoc

pnkfelix (Sep 03 2020 at 14:22, on Zulip):

Stable-nominations

T-compiler

libs-impl

T-rustdoc

pnkfelix (Sep 03 2020 at 14:22, on Zulip):

PRs S-waiting-on-team

T-compiler

libs-impl

pnkfelix (Sep 03 2020 at 14:22, on Zulip):

Issues of Note

Short Summary

pnkfelix (Sep 03 2020 at 14:23, on Zulip):

P-critical

T-compiler

pnkfelix (Sep 03 2020 at 14:23, on Zulip):
pnkfelix (Sep 03 2020 at 14:23, on Zulip):

(hey @nagisa , if wg-llvm needs help finding work to do ... )

pnkfelix (Sep 03 2020 at 14:24, on Zulip):

((I'm joking of course; I know everyone's busy))

pnkfelix (Sep 03 2020 at 14:24, on Zulip):

notably, this hasn't been bisected yet

pnkfelix (Sep 03 2020 at 14:25, on Zulip):

is the LLVM 11 upgrade in the current beta?

pnkfelix (Sep 03 2020 at 14:25, on Zulip):

(I'm just making a wild guess as to potential cause)

simulacrum (Sep 03 2020 at 14:25, on Zulip):

yeah

simulacrum (Sep 03 2020 at 14:26, on Zulip):

@cuviper seemed opposed to backing that out and I am... not sure yet, tentatively it feels like perhaps we should, if we can't find a targeted fix

pnkfelix (Sep 03 2020 at 14:26, on Zulip):

okay yeah it looks like @Trevor at least believes this is due to LLVM 11 upgrade

Santiago Pastorino (Sep 03 2020 at 14:26, on Zulip):

it seems that this is hitting a LLVM 11 blocker https://bugs.llvm.org/show_bug.cgi?id=46725

pnkfelix (Sep 03 2020 at 14:27, on Zulip):

well, I'd want to be careful about backing LLVM 11 out. At the very least, I'd want to compare what bugs were fixed by the upgrade

simulacrum (Sep 03 2020 at 14:27, on Zulip):

exactly

Santiago Pastorino (Sep 03 2020 at 14:27, on Zulip):

there's a discussion about it here https://github.com/rust-lang/rust/pull/73526#issuecomment-685461597

pnkfelix (Sep 03 2020 at 14:27, on Zulip):

anyway

pnkfelix (Sep 03 2020 at 14:28, on Zulip):

the most important thing for me right now is that we find an owner for this issue

pnkfelix (Sep 03 2020 at 14:29, on Zulip):

/me goes to skim the LLVM issue

pnkfelix (Sep 03 2020 at 14:31, on Zulip):

/me is tempted to self-assign ...

cuviper (Sep 03 2020 at 14:32, on Zulip):

I just want to point out, LLVM release blockers are self-nominated -- it doesn't really mean that it was "blessed" in any sense to definitely prevent release

pnkfelix (Sep 03 2020 at 14:32, on Zulip):

I'll take ownership of #76042

pnkfelix (Sep 03 2020 at 14:32, on Zulip):

to try to remember to evaluate whether to back out the LLVM 11 upgrade

pnkfelix (Sep 03 2020 at 14:33, on Zulip):

(and to do some cleanup of the issue; e.g. its still tagged as needs-bisection; and it would be good to formally confirm that the LLVM 11 upgrade is the cause, which isn't logged on the issue itself.)

pnkfelix (Sep 03 2020 at 14:33, on Zulip):

next

pnkfelix (Sep 03 2020 at 14:33, on Zulip):
Aaron Hill (Sep 03 2020 at 14:33, on Zulip):

I'll have a PR up for that in a few minutes

pnkfelix (Sep 03 2020 at 14:34, on Zulip):

sounds great

pnkfelix (Sep 03 2020 at 14:34, on Zulip):

libs-impl

T-rustdoc

pnkfelix (Sep 03 2020 at 14:34, on Zulip):

Unassigned P-high regressions

Beta regressions

pnkfelix (Sep 03 2020 at 14:35, on Zulip):
pnkfelix (Sep 03 2020 at 14:35, on Zulip):

I feel like we should assign this to either @Esteban Küber or to @nikomatsakis

pnkfelix (Sep 03 2020 at 14:36, on Zulip):

oh and @nikomatsakis last week suggested @Matthew Jasper as a potential other assignee

nikomatsakis (Sep 03 2020 at 14:37, on Zulip):

I don't think I am realistically going to be able to do much work here

pnkfelix (Sep 03 2020 at 14:37, on Zulip):

yeah reviewing the discussion last week we pretty firmly stated that we wouldn't assign it to @nikomatsakis

Esteban Küber (Sep 03 2020 at 14:37, on Zulip):

I can take a look, but am time constrained.

pnkfelix (Sep 03 2020 at 14:37, on Zulip):

(maybe we need a label E-dont-assign-to-niko)

pnkfelix (Sep 03 2020 at 14:38, on Zulip):

@Esteban Küber okay how about if I assign it to you, and if there's no progress by next week, we can revisit?

Esteban Küber (Sep 03 2020 at 14:38, on Zulip):

Sounds good to me

pnkfelix (Sep 03 2020 at 14:39, on Zulip):

@Santiago Pastorino does the wg-prioritization currently go over all the P-highs, including assigned ones? Specifically, would they know to put an issue like this back onto the agenda if no progress is logged on it (or if a lack of progress is specifically logged on it)?

Santiago Pastorino (Sep 03 2020 at 14:39, on Zulip):

we don't

Santiago Pastorino (Sep 03 2020 at 14:40, on Zulip):

but we could :)

pnkfelix (Sep 03 2020 at 14:40, on Zulip):

okay. just wanted to check

pnkfelix (Sep 03 2020 at 14:40, on Zulip):

what I'll do is nominate it

pnkfelix (Sep 03 2020 at 14:40, on Zulip):

and assign it to @Esteban Küber

Santiago Pastorino (Sep 03 2020 at 14:40, on Zulip):

right

pnkfelix (Sep 03 2020 at 14:40, on Zulip):

that way we will circle back to it

pnkfelix (Sep 03 2020 at 14:40, on Zulip):

one way or another next week. (Unless its fixed by then!)

Santiago Pastorino (Sep 03 2020 at 14:41, on Zulip):

pnkfelix said:

Santiago Pastorino does the wg-prioritization currently go over all the P-highs, including assigned ones? Specifically, would they know to put an issue like this back onto the agenda if no progress is logged on it (or if a lack of progress is specifically logged on it)?

maybe a discussion about checking beta regressions > P-high or something like that is worth, but we can do that in a separate topic of course :)

pnkfelix (Sep 03 2020 at 14:42, on Zulip):

oh actualy

pnkfelix (Sep 03 2020 at 14:42, on Zulip):

technically since this is a beta-regression, nominating shouldn't be necessary, because wg-prioritization does go over all the beta-regressions each week, right?

pnkfelix (Sep 03 2020 at 14:43, on Zulip):

anyway we can move along

pnkfelix (Sep 03 2020 at 14:43, on Zulip):

Nightly regressions

pnkfelix (Sep 03 2020 at 14:44, on Zulip):

wait, is this still only a nightly regression?

pnkfelix (Sep 03 2020 at 14:44, on Zulip):

The issue dates from July.

pnkfelix (Sep 03 2020 at 14:45, on Zulip):

this seems like it might be a stable-to-stable regression now? am I misunderstanding?

Santiago Pastorino (Sep 03 2020 at 14:45, on Zulip):

ohh I think you're right

pnkfelix (Sep 03 2020 at 14:46, on Zulip):

okay

Esteban Küber (Sep 03 2020 at 14:47, on Zulip):

These two are...the same, aren't they?

Esteban Küber (Sep 03 2020 at 14:47, on Zulip):

Same underlying cause?

pnkfelix (Sep 03 2020 at 14:47, on Zulip):

also.... maybe I'm misundertanding the diagnostics, but is #74400 related to (or even a duplicate of) ...

pnkfelix (Sep 03 2020 at 14:47, on Zulip):

yes excatly

pnkfelix (Sep 03 2020 at 14:47, on Zulip):

duplicate of #75791 ?

Santiago Pastorino (Sep 03 2020 at 14:48, on Zulip):

it seems like that yeah

Esteban Küber (Sep 03 2020 at 14:48, on Zulip):

Let's at least link them, if not close one

Santiago Pastorino (Sep 03 2020 at 14:48, on Zulip):

pnkfelix said:

duplicate of #75791 ?

it says beta regression, should also be stable regression

pnkfelix (Sep 03 2020 at 14:48, on Zulip):

yeah I wrote a comment on #74400

pnkfelix (Sep 03 2020 at 14:49, on Zulip):

lets move along in meeting, but @Esteban Küber maybe you could figure out if they are truly duplicates, and if so, identify which one to close a duplicate?

Santiago Pastorino (Sep 03 2020 at 14:49, on Zulip):

I wrote a comment on #75791 :joy:

pnkfelix (Sep 03 2020 at 14:49, on Zulip):

next up

pnkfelix (Sep 03 2020 at 14:49, on Zulip):

Performance logs

A quiet week for the most part with the exception of two PRs. The first,
#76027, was a rather large regression that was soon fixed by #76030. The net result seems to be a small improvement overall on optimized and debug builds.

Triage done by @ecstatic-morse.
Revision range: [03017003c77d782cf7ed841a05d7c628a9b93f25..d927e5a655809b6b20501889e093c085d6ffe6f7][range]

[range]: https://perf.rust-lang.org/?start=03017003c77d782cf7ed841a05d7c628a9b93f25&end=d927e5a655809b6b20501889e093c085d6ffe6f7&absolute=false&stat=instructions%3Au

1 Regression, 2 Improvements, 0 of them in rollups.

pnkfelix (Sep 03 2020 at 14:49, on Zulip):

Regressions

#76027 ty: remove obsolete pretty printer

pnkfelix (Sep 03 2020 at 14:50, on Zulip):

Improvements

#75754 Switch to Snappy compression for metadata

#76030 cg\_llvm: fewer_names in uncached_llvm_type

pnkfelix (Sep 03 2020 at 14:50, on Zulip):

Nags requiring follow up

None

pnkfelix (Sep 03 2020 at 14:51, on Zulip):

sounds good, or at least all is under control

pnkfelix (Sep 03 2020 at 14:51, on Zulip):

next up

pnkfelix (Sep 03 2020 at 14:51, on Zulip):

Nominated Issues

T-compiler

pnkfelix (Sep 03 2020 at 14:51, on Zulip):
pnkfelix (Sep 03 2020 at 14:51, on Zulip):

oops (fixed)

pnkfelix (Sep 03 2020 at 14:51, on Zulip):

so on #75899

pnkfelix (Sep 03 2020 at 14:52, on Zulip):

is @eddyb here?

Santiago Pastorino (Sep 03 2020 at 14:54, on Zulip):

pinged Eddy on Discord just in case, leave that issue to the end maybe?

pnkfelix (Sep 03 2020 at 14:55, on Zulip):

so in essence we're seeing a case where an unsizing coercion works when the unsized compoent is the last element in a tuplie, but not for a tuple-struct

pnkfelix (Sep 03 2020 at 14:56, on Zulip):

but you need a feature flag to observe the (working) behavior on vanilla tuple

pnkfelix (Sep 03 2020 at 14:56, on Zulip):

@nikomatsakis I don't think this is a language issue; i.e. I don't think the language team needs to approve that this should work, right?

nikomatsakis (Sep 03 2020 at 14:56, on Zulip):

sorry, I've been kind of distracted this meeting

nikomatsakis (Sep 03 2020 at 14:56, on Zulip):

let me review

pnkfelix (Sep 03 2020 at 14:56, on Zulip):

("this" being fn coerce_newtype, that is)

nikomatsakis (Sep 03 2020 at 14:57, on Zulip):

I think I agree

pnkfelix (Sep 03 2020 at 14:58, on Zulip):

but at the same time, I think this may get into details of trait system that would be better off discussed amongst a targetted team

pnkfelix (Sep 03 2020 at 14:58, on Zulip):

hypothetically a domain wg dedicated to the traits system

pnkfelix (Sep 03 2020 at 14:59, on Zulip):

at least, that's my gut reaction when it comes to questions about the semantics of normalizing associated items

pnkfelix (Sep 03 2020 at 15:00, on Zulip):

I guess this is all a way for me to say that I think @eddyb is trying to get attention paid to this issue, but I don't think it needs the attention of the whole T-compiler team

pnkfelix (Sep 03 2020 at 15:00, on Zulip):

I'm going to move along now, since time is almost up

pnkfelix (Sep 03 2020 at 15:00, on Zulip):
pnkfelix (Sep 03 2020 at 15:01, on Zulip):

@Santiago Pastorino as part of the review of rust#76247, did you see if any LLVM issue was filed regarding the performance regression?

Santiago Pastorino (Sep 03 2020 at 15:01, on Zulip):

I have checked the blockers and at least is not part of the blockers

Santiago Pastorino (Sep 03 2020 at 15:02, on Zulip):

didn't check all the open LLVM issues

Santiago Pastorino (Sep 03 2020 at 15:02, on Zulip):

it may worth doing so

pnkfelix (Sep 03 2020 at 15:02, on Zulip):

okay. I think filing a bug with LLVM is a good next step

pnkfelix (Sep 03 2020 at 15:02, on Zulip):

it can be difficult, i have found, to search their database

pnkfelix (Sep 03 2020 at 15:02, on Zulip):

and also I'm not certain that old bugs even get attention

Santiago Pastorino (Sep 03 2020 at 15:02, on Zulip):

right

pnkfelix (Sep 03 2020 at 15:02, on Zulip):

so I wouldn't be afraid to file a new one, personally, as long as you've made a reasonable attempt to look for pre-existing issue

pnkfelix (Sep 03 2020 at 15:03, on Zulip):

Okay, I think that's everything

pnkfelix (Sep 03 2020 at 15:03, on Zulip):

thanks to everyone in @T-compiler/meeting for attending!

Santiago Pastorino (Sep 03 2020 at 19:09, on Zulip):

next week we will have @T-compiler/WG-meta and @WG-mir-opt checkins

Santiago Pastorino (Sep 03 2020 at 19:09, on Zulip):

trying a new approach about notifying a week in advance :)

Santiago Pastorino (Sep 03 2020 at 19:10, on Zulip):

@nikomatsakis about @T-compiler/WG-meta, I think there's nothing right?

Santiago Pastorino (Sep 03 2020 at 19:10, on Zulip):

@oli could you provide next week's checkin for @WG-mir-opt ?

lqd (Sep 03 2020 at 19:12, on Zulip):

I think #75791 and #74400 (and probably others) are all instances of the NLL migrate mode version of the "higher ranked subtype" NLL errors, which don't go through the "nice region error" reporting code

lqd (Sep 03 2020 at 20:26, on Zulip):

(I've added a comment pointing out why they don't go through the nice region error reporting code as the situation is the same as the last time I looked at it: it handles TraitRefs and those are PolyTraitRefs. I didn't know how to improve these cases then, and hopefully Esteban will now)

eddyb (Sep 03 2020 at 21:11, on Zulip):

pnkfelix said:

is eddyb here?

wow I managed to repeat the same mistake two weeks in a row

Last update: Nov 25 2020 at 03:00UTC