Stream: t-compiler/wg-prioritization

Topic: I-prioritize #71359 Regression in usable type complexity: ov


triagebot (Apr 20 2020 at 16:44, on Zulip):

@WG-prioritization issue #71359 has been requested for prioritization.

Jonas Schievink (Apr 20 2020 at 16:55, on Zulip):

This might be expected fallout, but it's good to check. Can users set the recursion limit to get around this?

Wesley Wiser (Apr 20 2020 at 17:25, on Zulip):

Having a backtrace for the error would be helpful

LeSeulArtichaut (Apr 20 2020 at 17:26, on Zulip):

Apparently,

(Running with RUST_BACKTRACE does not change the output.)

Wesley Wiser (Apr 20 2020 at 17:40, on Zulip):

If we run with -Ztreat-err-as-bug, we should get a backtrace where that error is being generated.

LeSeulArtichaut (Apr 20 2020 at 17:51, on Zulip):

Ah, ok

LeSeulArtichaut (Apr 21 2020 at 16:00, on Zulip):

@Wesley Wiser I tried to run:

RUST_BACKTRACE=1 cargo +nightly rustc -- -Ztreat-err-as-bug

But it didn't ICE, so I have no backtrace

LeSeulArtichaut (Apr 21 2020 at 16:00, on Zulip):

Any reason why?

Wesley Wiser (Apr 21 2020 at 20:29, on Zulip):

Huh, I've never seen treat-err-as-bug not work...

Santiago Pastorino (Apr 21 2020 at 20:30, on Zulip):

this is a bit surprising to me too this is not showing any pointer to what's going on

Wesley Wiser (Apr 21 2020 at 20:31, on Zulip):

If it's related to #32498 as the author mentions, I suspect the error is coming from the codegen backend which might not respect treat-err-as-bug

Santiago Pastorino (Apr 21 2020 at 20:38, on Zulip):

I guess it may be nice to see what happens if we revert #70896

Santiago Pastorino (Apr 21 2020 at 20:38, on Zulip):

just in case and maybe ping @cuviper

Santiago Pastorino (Apr 21 2020 at 20:41, on Zulip):

this is the last unprioritized one :)

Wesley Wiser (Apr 21 2020 at 21:14, on Zulip):

I think there may be a standing policy for this kind of issue

Santiago Pastorino (Apr 21 2020 at 21:15, on Zulip):

@Wesley Wiser what do you mean?

Wesley Wiser (Apr 21 2020 at 21:15, on Zulip):

I feel like I've seen this kind of issue before

Wesley Wiser (Apr 21 2020 at 21:16, on Zulip):

And I feel like this maybe just be acceptable breakage

Wesley Wiser (Apr 21 2020 at 21:16, on Zulip):

Sort of in the same vein as the macro recursion limit stuff

Santiago Pastorino (Apr 21 2020 at 21:16, on Zulip):

I see, maybe it's good to nominate it?

Wesley Wiser (Apr 21 2020 at 21:17, on Zulip):

Maybe @pnkfelix has an opinion?

Wesley Wiser (Apr 21 2020 at 21:18, on Zulip):

TLDR: a recently nightly caused a crate to start breaking during codegen with type length limit exceeded errors

pnkfelix (Apr 21 2020 at 22:10, on Zulip):

hmm

pnkfelix (Apr 21 2020 at 22:11, on Zulip):

maybe P-medium but nominate for discussion...

Santiago Pastorino (Apr 22 2020 at 11:28, on Zulip):

@pnkfelix do you want to nominate it to just discuss this particular issue or what @Wesley Wiser have said, that we need a policy for this kind of issues?

triagebot (Apr 22 2020 at 11:30, on Zulip):

Issue #71359's prioritization request has been removed.

Wesley Wiser (Apr 22 2020 at 13:04, on Zulip):

I think it's probably worth having a small discussion in the meeting about this

pnkfelix (Apr 22 2020 at 15:01, on Zulip):

Santiago Pastorino said:

pnkfelix do you want to nominate it to just discuss this particular issue or what Wesley Wiser have said, that we need a policy for this kind of issues?

Maybe both. At first my intent with my nomination suggestion was for more of a "announcement, we prioritized this as P-medium but it may be of general interest/concern. But now I am also thinking that @Wesley Wiser is making a good point that we should discuss what the policy is for cases like this. We don't think we want instances of this problem to just gradually accumulate...

Santiago Pastorino (Apr 22 2020 at 15:32, on Zulip):

@pnkfelix :love:

LeSeulArtichaut (May 01 2020 at 15:50, on Zulip):

From what I've seen in the Crater report, 6 crates broke because of this

LeSeulArtichaut (May 01 2020 at 16:20, on Zulip):

There's nothing particularly worrying IMHO

Last update: Jun 05 2020 at 23:05UTC