Stream: t-compiler

Topic: #54818 pre-triage weekly 2019-02-28


pnkfelix (Feb 28 2019 at 11:50, on Zulip):

This is the topic where I will be doing pre-triage prior to the weekly T-compiler meeting which will commence in about three hours, in another topic on this stream

pnkfelix (Feb 28 2019 at 11:53, on Zulip):

(ah sadly Zulip's url system does not provide redirections in response to edited topics. I wonder if that has been proposed as a feature request.)

pnkfelix (Feb 28 2019 at 11:54, on Zulip):

so, first up, p-high T-compiler issues

pnkfelix (Feb 28 2019 at 11:54, on Zulip):

first one is: "NLL migrate mode erroneously downgrades error with nested closures, yielding use-after-free" #58776; this is being dealt with and has a PR at #58788

pnkfelix (Feb 28 2019 at 11:55, on Zulip):

oh. You know what, I'm going to start being smart

pnkfelix (Feb 28 2019 at 11:55, on Zulip):

(since this is pre-triage, I will take advantage of freedom to reorder process to be smarter)

pnkfelix (Feb 28 2019 at 11:56, on Zulip):

namely, I'm going to start reviewing the nominated before the P-high ones, since the process of going through the former leads to them being tagged as the latter

pnkfelix (Feb 28 2019 at 12:03, on Zulip):

(had to pause for a bit to update the description on #54818 to reflect this new process)

pnkfelix (Feb 28 2019 at 12:04, on Zulip):

so there are six T-compiler I-nominated unprioritized issues

pnkfelix (Feb 28 2019 at 12:05, on Zulip):

First: "rls no longer builds after rust-lang/rust#58321" #58765; sounds P-high to me. Tagging as such.

pnkfelix (Feb 28 2019 at 12:05, on Zulip):

next: "Wrong optimization of Some(Rc<RefCell<...>>) in thread_local! (STATUS_ILLEGAL_INSTRUCTION)" #58684

pnkfelix (Feb 28 2019 at 12:07, on Zulip):

also sounds P-high to me. Also would be nice to 1. narrow the test case and/or 2. bisect which rustc injected, assuming it was relatively recent injection (though it does reproduce on stable 1.32)

pnkfelix (Feb 28 2019 at 12:09, on Zulip):

next: "Type inference fails even though all types are known" #58517

pnkfelix (Feb 28 2019 at 12:09, on Zulip):

holy cow bisection showed this was injected way way back between 1.12 and 1.13 :mantelpiece_clock:

pnkfelix (Feb 28 2019 at 12:16, on Zulip):

I'm going to triage #58517 as P-medium for now (since this is not e.g. a soundness issue and one can work around it by e.g. introducing a ) but leave the I-nominated label so that people get the chance to object at the meeting.

pnkfelix (Feb 28 2019 at 12:16, on Zulip):

It definitely seems goofy to me, though

pnkfelix (Feb 28 2019 at 12:18, on Zulip):

next: "Implement "pipelined" rustc compilation (compiler side)" #58465

pnkfelix (Feb 28 2019 at 12:19, on Zulip):

one can see discussion of this on the corresponding cargo issue

csmoe (Feb 28 2019 at 12:20, on Zulip):

@pnkfelix sorry for cutting in. as for the rlshttps://github.com/rust-lang/rust/issues/58765, I PR'ed just now https://github.com/rust-lang/rls/pull/1384

pnkfelix (Feb 28 2019 at 12:20, on Zulip):

no problem about cutting in; I wouldn't log this here if I didn't want that.

pnkfelix (Feb 28 2019 at 12:21, on Zulip):

I don't know how high a priority we want to put on #58465. So I'm not going to assign any priority; instead I'm going to leave it nominated in the hopes that we discuss it today or soon thereafter.

pnkfelix (Feb 28 2019 at 12:21, on Zulip):

(and then the team can collectively answer the question of what P-label to apply)

pnkfelix (Feb 28 2019 at 12:21, on Zulip):

next: "Rustc should use a variable other than RUST_LOG for env_logger." #57985

pnkfelix (Feb 28 2019 at 12:22, on Zulip):

I personally don't think this is a high priority item, but I do think its worth discussing, and maybe would be a good mentorship bug?

pnkfelix (Feb 28 2019 at 12:23, on Zulip):

I'm going to mark #57985 as P-medium, but keep the nomination label and tag as E-needs-mentor.

pnkfelix (Feb 28 2019 at 12:24, on Zulip):

next: " Function pointer docs may need updating" #46989

pnkfelix (Feb 28 2019 at 12:24, on Zulip):

@Aaron Turon has started looking into this

pnkfelix (Feb 28 2019 at 12:25, on Zulip):

the fallout that came out of universes (where said fallout has seen been undone by the re-introduction of a leak-check) implies to me that this is P-high.

pnkfelix (Feb 28 2019 at 12:27, on Zulip):

okay that's all the nominated issues that were specifically tagged with T-compiler

pnkfelix (Feb 28 2019 at 12:27, on Zulip):

next, I'll quietly do a pre-pass over all the unprioritized nominated issues (for any team). But I'll only announce the ones, if any, strike me as needing a T-compiler label but do not yet have one.

pnkfelix (Feb 28 2019 at 12:28, on Zulip):

I don't see any that strike me as needing T-compiler's attention.

pnkfelix (Feb 28 2019 at 12:29, on Zulip):

So, now that that is done, lets go through the actual P-high issue list

pnkfelix (Feb 28 2019 at 12:29, on Zulip):

I already mentioned "NLL migrate mode erroneously downgrades error with nested closures, yielding use-after-free" #58776 at the outset, no need to revisit here.

pnkfelix (Feb 28 2019 at 12:31, on Zulip):

next: " rls no longer builds after rust-lang/rust#58321" #58765. as @csmoe mentioned, this now has a PR to fix it. I'm going to remove the nomination label.

pnkfelix (Feb 28 2019 at 12:31, on Zulip):

next: "Wrong optimization of Some(Rc<RefCell<...>>) in thread_local! (STATUS_ILLEGAL_INSTRUCTION)" #58684

pnkfelix (Feb 28 2019 at 12:32, on Zulip):

assigning to self for initial investigation.

pnkfelix (Feb 28 2019 at 12:32, on Zulip):

and removing nomination label

pnkfelix (Feb 28 2019 at 12:32, on Zulip):

next: "TyLayout::field_type ICE on 1.34.0-nightly 865cb7010 2019-02-10" #58610

pnkfelix (Feb 28 2019 at 12:33, on Zulip):

lets update that title to be a little more specific. (done)

pnkfelix (Feb 28 2019 at 12:34, on Zulip):

this needs a standalone test

pnkfelix (Feb 28 2019 at 12:35, on Zulip):

I'll wait until the meeting to see if we can get someone to volunteer. (and I'll post a request for such a volunteer now.)

csmoe (Feb 28 2019 at 12:37, on Zulip):

@pnkfelix I wanna take care of the test. but what is standalone test?

pnkfelix (Feb 28 2019 at 12:38, on Zulip):

By standalone I mean a snippet of code we can feed into rustc that exposes the bug

pnkfelix (Feb 28 2019 at 12:38, on Zulip):

ideally its something small that you can include the source code in the description, and a link to the playpen with the same code.

csmoe (Feb 28 2019 at 12:39, on Zulip):

okay, gotcha

lqd (Feb 28 2019 at 12:39, on Zulip):

Matthew's PR #58788 with a possible fix for #58776 is beta-nominated, is that for the "real beta" or a point release (as the new release drops later today) ?

pnkfelix (Feb 28 2019 at 12:39, on Zulip):

anyway I can assign #58610 to you then, @csmoe , for facotring out the test?

csmoe (Feb 28 2019 at 12:39, on Zulip):

@pnkfelix yep

pnkfelix (Feb 28 2019 at 12:40, on Zulip):

Matthew's PR #58788 with a possible fix for #58776 is beta-nominated, is that for the "real beta" or a point release (as the new release drops later today) ?

It doesn't seem to be worth a point release to me.

pnkfelix (Feb 28 2019 at 12:40, on Zulip):

since, if I understand correctly, all instances of this bug are emitting a warning

lqd (Feb 28 2019 at 12:41, on Zulip):

true

pnkfelix (Feb 28 2019 at 12:41, on Zulip):

and its hopefully a scary warning :spooky:

pnkfelix (Feb 28 2019 at 12:41, on Zulip):

But we will discuss all the beta-nominations at the meeting itself

pnkfelix (Feb 28 2019 at 12:42, on Zulip):

One of my hopes/plans is to not attempt to handle beta-nominations during pre-triage, at least not in terms of trying to initiate any sort of action on them during the pre-triage process.

pnkfelix (Feb 28 2019 at 12:42, on Zulip):

though I guess mentioning them in this channel would at least alert people to their existence? I don't know.

pnkfelix (Feb 28 2019 at 12:43, on Zulip):

pnkfelix yep

great, thanks @csmoe

Matthew Jasper (Feb 28 2019 at 12:43, on Zulip):

Beta nominated should always mean real beta, stable nominated should be used for point releases.

pnkfelix (Feb 28 2019 at 12:44, on Zulip):

right, I assume @lqd was asking because there may have been a kind of race condition, at least in the different parties' mental models of where the trains were/are

pnkfelix (Feb 28 2019 at 12:45, on Zulip):

(where if something is beta-nominated and then the beta-to-stable promotion happens, we need to ask whether it should then be stable-nominated too)

pnkfelix (Feb 28 2019 at 12:45, on Zulip):

but maybe that was too much mind-reading on my part

pnkfelix (Feb 28 2019 at 12:46, on Zulip):

next P-high issue: "rustc 1.32.0 produces faulty wasm code" #58548

pnkfelix (Feb 28 2019 at 12:47, on Zulip):

this has been reported as a bug to LLVM upstream, which has merged a fix

pnkfelix (Feb 28 2019 at 12:48, on Zulip):

and @Nikita Popov assigned themselves to handle it.

pnkfelix (Feb 28 2019 at 12:49, on Zulip):

so this looks under control

pnkfelix (Feb 28 2019 at 12:49, on Zulip):

next P-high issue: "fn generated by macro exported from crate loses global #![allow(non_snake_case)]" #58502

pnkfelix (Feb 28 2019 at 12:52, on Zulip):

reading over this bug, I don't even know what the "right" behavior should be here.

pnkfelix (Feb 28 2019 at 12:52, on Zulip):

Do we have a WG-lint or some other team dedicated to what lints are "suppposed" to do?

pnkfelix (Feb 28 2019 at 12:53, on Zulip):

I guess I'll leave this nominated for discussion at the meeting itself.

pnkfelix (Feb 28 2019 at 12:53, on Zulip):

next P-high issue: "Nightly compiler 'inconsistent resolution for an import' for crate" #58499

pnkfelix (Feb 28 2019 at 12:54, on Zulip):

I'm still assuming that @Vadim Petrochenkov is going to address this in some manner.

pnkfelix (Feb 28 2019 at 12:54, on Zulip):

but you know what, I'm supposed to be getting my feet wet with resolution anyway, so I'm going to add myself to the assignee list here.

pnkfelix (Feb 28 2019 at 12:55, on Zulip):

next P-high issue: "Compiler panic with associated constant" #58435

pnkfelix (Feb 28 2019 at 12:55, on Zulip):

kee-rap I have not yet followed through on this.

pnkfelix (Feb 28 2019 at 12:56, on Zulip):

but it's been broken on stable (and beta) for some amount of time so its not hugely bad that I missed the trains shifting

pnkfelix (Feb 28 2019 at 12:56, on Zulip):

anyway I'll try to follow up soon

pnkfelix (Feb 28 2019 at 12:57, on Zulip):

next P-high issue: ""Cannot create local mono-item" ICE building cortex-m code on nightly" #58323

pnkfelix (Feb 28 2019 at 12:57, on Zulip):

this is assigned and has a PR so I think its in good hands

pnkfelix (Feb 28 2019 at 12:58, on Zulip):

next: "ICE with std::mem::size_of with repr(packed) plus associated type" #58158

pnkfelix (Feb 28 2019 at 12:58, on Zulip):

I failed to follow-up on this one too.

pnkfelix (Feb 28 2019 at 12:59, on Zulip):

(I've been having too much fun looking at other ICEs) :snowflake:

pnkfelix (Feb 28 2019 at 13:00, on Zulip):

next P-high issue: "beta 1.33 seems to break tarpaulin on multithreading" #58104

pnkfelix (Feb 28 2019 at 13:01, on Zulip):

hmm dialogue on ticket indicates there is likely to be nothing actionable on our side here.

pnkfelix (Feb 28 2019 at 13:02, on Zulip):

I'm going to tag as I-nominated, with a comment sayingI want to discuss it at upcoming T-compiler meeting but also indicate that I am inclined to close as unactionable.

pnkfelix (Feb 28 2019 at 13:03, on Zulip):

next P-high issue: "Regression from stable to nightly: nested impl trait is not allowed" #57979

pnkfelix (Feb 28 2019 at 13:04, on Zulip):

okay, for once we have an issue I self-assigned that I actually did something about

pnkfelix (Feb 28 2019 at 13:05, on Zulip):

namely, I have put up PR #58608 which implements a warning period for the change in static semantics described in #57979

pnkfelix (Feb 28 2019 at 13:06, on Zulip):

but I did not manage to get PR #58608 landed in time for the nightly-to-beta cut earlier this week. And it doesn't make sense to me to land PR #58608 unless it also ends up back ported to the beta: that is, I don't see the point of having a hard break for 6 weeks followed by a warning period of unspecified length.

pnkfelix (Feb 28 2019 at 13:06, on Zulip):

(see my comment here which essentially says the same thing.)

pnkfelix (Feb 28 2019 at 13:07, on Zulip):

so, yeah. We'll discuss this issue more when we talk about beta-nominations.

pnkfelix (Feb 28 2019 at 13:09, on Zulip):

next P-high issue: "Nightly rustc crashes with "unexpected region in query response"" #57464

pnkfelix (Feb 28 2019 at 13:11, on Zulip):

This, #57464, is the other bug I have been working on. I have a WIP generalization of a previously posted PR (#58649) that should fix this more completely. Hopefully that PR will be up soon (i'm trying to reduce it a little before I post it to make it easier to backport.)

pnkfelix (Feb 28 2019 at 13:13, on Zulip):

next P-high issue: "[NLL] Bad higher ranked subtype error" #57374. This is NLL specific. @lqd has been working on it. (The regression has also been temporarily un-regressed via the reintroduction of the leak-check, as noted on the ticket itself.)

pnkfelix (Feb 28 2019 at 13:13, on Zulip):

anyway this seems under control. But I'm also tempted to downgrade to P-medium...

pnkfelix (Feb 28 2019 at 13:14, on Zulip):

(I guess the error really is/was attrociously bad before. Okay I'll leave it at P-high under the assumption that it is still that bad.)

pnkfelix (Feb 28 2019 at 13:14, on Zulip):

next P-high bug: "Borrow checker incorrectly accepts code when calling function with complex lifetime bounds through a fn pointer" #57170

pnkfelix (Feb 28 2019 at 13:15, on Zulip):

This (#57170) has a PR (#57202) and will hopefully be fixed very soon. In any case it is in good hands.

pnkfelix (Feb 28 2019 at 13:16, on Zulip):

next P-high issue: "[NLL] prohibit "two-phase borrows" with existing borrows?" #56254

pnkfelix (Feb 28 2019 at 13:16, on Zulip):

progress has been ongoing here with the NLL team, thank in no small part to @Matthew Jasper 's tireless efforts

pnkfelix (Feb 28 2019 at 13:16, on Zulip):

we have a crater run being applied to @Matthew Jasper 's PR #58739

pnkfelix (Feb 28 2019 at 13:17, on Zulip):

where it is currently number four in the queue... so yeah, we may not see result for that for a while.

pnkfelix (Feb 28 2019 at 13:17, on Zulip):

anyway, its in good hands.

pnkfelix (Feb 28 2019 at 13:17, on Zulip):

next: " user type annotations are captured post normalization" #54940

pnkfelix (Feb 28 2019 at 13:18, on Zulip):

I marked this P-high yesterday and nominated it for discussion. According to @nikomatsakis progress on #54940 is blocked on lazy-normalization, so I was hoping to get an outline (maybe today?) from the @WG-compiler-traits team about what the game plan and/or schedule is for lazy-normalization.

pnkfelix (Feb 28 2019 at 13:20, on Zulip):

anyway its nominated so we'll see it on that list at the actual meeting

pnkfelix (Feb 28 2019 at 13:20, on Zulip):

next P-high: "[nll] change how MIR represents places" #52708

pnkfelix (Feb 28 2019 at 13:21, on Zulip):

work here is ongoing; see the place 2.0 topic.

pnkfelix (Feb 28 2019 at 13:22, on Zulip):

next P-high: "Function pointer docs may need updating" #46989. I already discussed this up above when I was going through the nominations. I assume @Aaron Turon is still planning to take point on it.

pnkfelix (Feb 28 2019 at 13:22, on Zulip):

next P-high: "two-phase-borrows need a specification" #46901; I have no progress to report here.

pnkfelix (Feb 28 2019 at 13:23, on Zulip):

final P-high: "match arm bindings have weird lifetimes" #46525

pnkfelix (Feb 28 2019 at 13:23, on Zulip):

I revised the priority from P-medium to P-high on this last week

pnkfelix (Feb 28 2019 at 13:23, on Zulip):

because I want to double-check the assumption we have posted about it

pnkfelix (Feb 28 2019 at 13:24, on Zulip):

(and also, it is entirely possible that some of @Matthew Jasper 's changes to codegen have silently handled this.)

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

but apart from changing priority, I have not yet done anything here.

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

okay, that's all the P-high issues.

pnkfelix (Feb 28 2019 at 13:29, on Zulip):

for beta-nominations, I'm going to let us handle those (along with the remaining I-nominations) at the meeting itself.

pnkfelix (Feb 28 2019 at 13:29, on Zulip):

but I will take a moment now to at least add T-compiler tags when needed

pnkfelix (Feb 28 2019 at 13:29, on Zulip):

Added T-compiler to "Don't promote function calls to nonpromotable things" #58784

pnkfelix (Feb 28 2019 at 13:29, on Zulip):

Added T-compiler to "Make migrate mode work at item level granularity" #58788

pnkfelix (Feb 28 2019 at 13:33, on Zulip):

no stable nominations, thank goodness

pnkfelix (Feb 28 2019 at 13:34, on Zulip):

next, stable to beta regressions

pnkfelix (Feb 28 2019 at 13:35, on Zulip):

the first four of these were opened in the last week and do not have P-label nor I-nominated, so we haven't seen them yet here.

pnkfelix (Feb 28 2019 at 13:35, on Zulip):

(I probably should have done a prepass over them in the beginning, up above)

pnkfelix (Feb 28 2019 at 13:35, on Zulip):

first s2b regression: "Rustc panic when building bobbin-sdk" #58767

pnkfelix (Feb 28 2019 at 13:36, on Zulip):

marking P-high. has PR (#58784). Leaving assigned to @oli

pnkfelix (Feb 28 2019 at 13:37, on Zulip):

next s2b regression: "panic with "Layout mismatch when copying!"" #58742

pnkfelix (Feb 28 2019 at 13:38, on Zulip):

triage: P-high. Speculatively assigning to @oli

pnkfelix (Feb 28 2019 at 13:39, on Zulip):

next s2b regression: "compiler error: lifetimes in associated types leading to a compiler error." #58694

pnkfelix (Feb 28 2019 at 13:41, on Zulip):

went from hard-error to ICE on code that has a visible feature-gate error.

pnkfelix (Feb 28 2019 at 13:41, on Zulip):

triage: P-medium, and assigning to self.

pnkfelix (Feb 28 2019 at 13:43, on Zulip):

next s2b regression: "ICE on rustc 1.34.0-nightly (633d75ac1 2019-02-21): index out of bounds" #58634

pnkfelix (Feb 28 2019 at 13:43, on Zulip):

this is also handled by PR #58784. @oli previously assigned themselves.

pnkfelix (Feb 28 2019 at 13:43, on Zulip):

so I'll just triage it as P-high

pnkfelix (Feb 28 2019 at 13:44, on Zulip):

that's all the stable-to-beta regressions

pnkfelix (Feb 28 2019 at 13:47, on Zulip):

All of the stable-to-nightly regressions appear to be triaged. that is, we visited them earlier in this topic, either because the are P-high or were I-nominated or are also stable-to-beta regressions.

pnkfelix (Feb 28 2019 at 13:47, on Zulip):

There is one issue waiting for our team; it is also marked I-nominated.

pnkfelix (Feb 28 2019 at 13:48, on Zulip):

so I think all of the triage work for the meeting itself is summarized in the beta-nominations and the I-nominations

pnkfelix (Feb 28 2019 at 13:49, on Zulip):

with that, I declare pre-triage over. Now I need to go afk to run my aforementioned errand

Matthew Jasper (Feb 28 2019 at 14:32, on Zulip):

(and also, it is entirely possible that some of Matthew Jasper 's changes to codegen have silently handled this.)

They didn't, but they make this easier to fix in the future. Once AST borrow check is completely gone this won't be that hard, although it's possible to fix without that.

Last update: Nov 16 2019 at 01:05UTC