[DO NOT MERGE] `-Znext-solver=globally` experiments by lcnr · Pull Request #133502 · rust-lang/rust

lcnr · 2024-11-26T15:26:47Z

A revival of #124812. See

Current status:

~~./x.py b --stage 2 passes 🎉~~

try builds succeed 🎉 🎉 🎉

first perf run 👻 second perf run 👻 third perf run 👻 fourth perf run 👻 fifth perf run 👻

crater

This does not detect hangs or memory issues. We are triaging the regressions in https://rust-lang.zulipchat.com/#narrow/channel/364551-t-types.2Ftrait-system-refactor/topic/crater.20triage.20.3A3/with/572783267 and welcome your help there.

date	#crates	#regressions
2025.04.11	100	2
2025.04.11	1000	27
2025.04.17	10000	456
2025.04.18	10000	437
2025.04.24	10000	164
2025.04.26	10000	108
2025.04.28	10000	91
2025.05.01	10000	145 woops
2025.05.03	624228¹	1585²
2025.05.05	8964³	931²
2025.05.06	4401³	726²
2025.05.07	2704³	668²
2025.05.09	2345³	664²
2025.09.20	701952¹	4739 + 7039 spurious
2025.10.02	11712³	2568 + 2014 spurious
2025.10.04	4582³	1173 + 1147 spurious²
2025.12.30	761102¹	1424 + 8938 spurious ²
2026.01.01	5745³	1371 + 3227 spurious ²
2026.01.06	4171³	1361 + 2623 spurious ²
2026.07.17	1014957¹	6502 + 11187 spurious ²
2026.07.20	17458³	991 + 3331 spurious ²
2026.07.23	4322³	959 + 1680 spurious ²
2026.07.31	1049848¹	1254 + 13493 spurious
2026.08.03	14035³	679 + 2245 spurious
2026.08.05	2915³	457 + 997 spurious

in-flight changes

do not prefer trivially true candidates with -Znext-solver #163928

r? @ghost

a complete crater run ↩ ↩² ↩³ ↩⁴ ↩⁵
with doubled recursion_limit when evaluating goals ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹²
only testing crates which may have regressed from the above run ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹²

compiler-errors · 2024-11-27T04:03:51Z

@bors try

[DO NOT MERGE] bootstrap with `-Znext-solver=globally` A revival of rust-lang#124812. Current status, we're failing in: - failing in `rustc_next_trait_solver` with 126 instances of the following error ``` error[E0311]: the parameter type `I` may not live long enough | help: consider adding an explicit lifetime bound --> compiler/rustc_next_trait_solver/src/solve/trait_goals.rs:624:53 | 624 ~ fn consider_structural_builtin_unsize_candidates<'a>( 625 ~ ecx: &mut EvalCtxt<'a, D>, 626 | goal: Goal<I, Self>, 627 ~ ) -> Vec<Candidate<I>> where I: 'a { ``` - `itertools` hangs, we're already encountered this hang in our previous attempt due to large type sizes. I believe that it's simply caused by a missing cache somewhere, potentially in `wf.rs`, but other visitors may also be responsible. See rust-itertools/itertools#945 for more details ### commits - rust-lang#133501 - rust-lang#133493 - 9456bfe and b21b116 reimplement candidate preference based on rust-lang#132325, not yet a separate PR - c3ef9cd is a rebased version of rust-lang#125334, unsure whether I actually want to land this PR for now r? `@ghost`

bors · 2024-11-27T04:05:03Z

⌛ Trying commit f631ca8 with merge ca04381...

compiler-errors · 2024-11-27T04:05:17Z

I also pushed:

I think this is sufficient to make the compiler build, or at least ./x.py build --stage=2 completes successfully on my local branch.

bors · 2024-11-27T06:15:40Z

💔 Test failed - checks-actions

bors · 2024-11-27T10:43:04Z

☔ The latest upstream changes (presumably #133527) made this pull request unmergeable. Please resolve the merge conflicts.

lqd · 2024-11-27T11:42:49Z

Next failure is on color-print-proc-macro-0.3.6 while building cargo.

pub fn repro() -> impl FnMut() {
    if true {
        || ()
    } else {
        || ()
    }
}

godbolt

compiler-errors · 2024-11-27T17:49:50Z

@bors try

[DO NOT MERGE] bootstrap with `-Znext-solver=globally` A revival of rust-lang#124812. Current status: `./x.py b --stage 2` passes 🎉 ### commits - rust-lang#133501 - rust-lang#133493 - 9456bfe and b21b116 reimplement candidate preference based on rust-lang#132325, not yet a separate PR - c3ef9cd is a rebased version of rust-lang#125334, unsure whether I actually want to land this PR for now - rust-lang#133517 * rust-lang#133518 * rust-lang#133519 * rust-lang#133520 * rust-lang#133521 * rust-lang#133524 r? `@ghost`

bors · 2024-11-27T17:51:02Z

⌛ Trying commit 6210ed3 with merge ac5ccad...

bors · 2024-11-27T20:03:42Z

💔 Test failed - checks-actions

compiler-errors · 2024-11-27T20:15:22Z

@bors try

[DO NOT MERGE] bootstrap with `-Znext-solver=globally` A revival of rust-lang#124812. Current status: `./x.py b --stage 2` passes 🎉 ### commits - rust-lang#133501 - rust-lang#133493 - 9456bfe and b21b116 reimplement candidate preference based on rust-lang#132325, not yet a separate PR - c3ef9cd is a rebased version of rust-lang#125334, unsure whether I actually want to land this PR for now - rust-lang#133517 * rust-lang#133518 * rust-lang#133519 * rust-lang#133520 * rust-lang#133521 * rust-lang#133524 r? `@ghost`

bors · 2024-11-27T20:16:33Z

⌛ Trying commit 8fa8f40 with merge 550ae0d...

lqd · 2024-11-27T20:26:10Z

I was reducing the new failure but you've already fixed it ^^

lcnr · 2026-10-01T22:32:34Z

Partially because I genuinely think getting the next solver stabilized asap is very useful as it blocks a lot of other work.

^{partially because I am slowly going insane, and the idea of being stuck while waiting on crater is :<<}

@craterbot p=6

craterbot · 2026-10-01T22:32:37Z

📝 Configuration of the pr-133502-29 experiment changed.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

craterbot · 2026-10-04T03:36:32Z

🚧 Experiment pr-133502-29 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

craterbot · 2026-10-06T22:41:45Z

🎉 Experiment pr-133502-29 is completed!
📊 10 regressed and 0 fixed (1148868 total)
📊 6863 spurious results on the retry-regressed-list.txt, consider a retry¹ if this is a significant amount.
📰 Open the summary report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

re-run the experiment with crates=https://crater-reports.s3.amazonaws.com/pr-133502-29/retry-regressed-list.txt ↩

traviscross · 2026-10-07T06:34:39Z

@craterbot check p=6 crates=https://crater-reports.s3.amazonaws.com/pr-133502-29/retry-regressed-list.txt

(Mirroring the priority from the original run.)

craterbot · 2026-10-07T06:34:48Z

👌 Experiment pr-133502-30 created and queued.
🤖 Automatically detected try build 5b237c9
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

traviscross · 2026-10-07T06:35:51Z

@craterbot p=1

(Looking at the queue, there are things pending for the release, and it seems better to not get between those.)

craterbot · 2026-10-07T06:35:54Z

📝 Configuration of the pr-133502-30 experiment changed.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

theemathas · 2026-10-07T06:51:19Z

@craterbot p=6

@traviscross see https://rust-lang.zulipchat.com/#narrow/channel/241545-t-release/topic/How.20to.20prioritize.20crater.20runs.3F/with/628634407

craterbot · 2026-10-07T06:51:22Z

📝 Configuration of the pr-133502-30 experiment changed.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

lcnr · 2026-10-07T06:58:37Z

something's wrong 🤔 that's too few failures 😅 we should have minijinja failing

@craterbot cancel

craterbot · 2026-10-07T06:58:40Z

🗑️ Experiment pr-133502-30 deleted!

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

lcnr · 2026-10-07T07:27:08Z

see https://rust-lang.zulipchat.com/#narrow/channel/364551-t-types.2Ftrait-system-refactor/topic/crater.20triage.20.3A3/near/629752801. we're comparing with nightly. nightly already has the new solver enabled. This is effectively a crater run of just #163589.

There should be a way to only run crater for failing crates + spurious regressions

lcnr · 2026-10-07T08:07:44Z

@bors try

rust-bors · 2026-10-07T09:12:14Z

☀️ Try build successful (CI)
Build commit: cc155fe (cc155fe68aae7ab0c83c7a5197b35ba12ec13c92)
Base parent: 8d1a764 (8d1a76430406c877b35d0b627e7f796dcf0dfeca)

lcnr · 2026-10-07T09:30:52Z

filtered the crates which also failed in the start run of #133502 (comment)

@craterbot run mode=check-only start=cc155fe68aae7ab0c83c7a5197b35ba12ec13c92+rustflags=-Znext-solver=coherence end=cc155fe68aae7ab0c83c7a5197b35ba12ec13c92 crates=https://gist.githubusercontent.com/lcnr/0e2a09bb6b565ee9392c664a3c8cb47d/raw/a7aee74336eeb45df44563106cc3c9fc5930eece/failed-crates.txt p=6

craterbot · 2026-10-07T09:30:56Z

👌 Experiment pr-133502-30 created and queued.
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

lcnr · 2026-10-07T09:47:55Z

we've got time, gonna fix the issues from #163589 first

@craterbot cancel :>

craterbot · 2026-10-07T09:47:58Z

🚨 Error: failed to parse the command

🆘 If you have any trouble with Crater please ask in t-infra on Zulip
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

lcnr · 2026-10-07T10:47:20Z

@bors try

rust-bors · 2026-10-07T10:47:27Z

⌛ Trying commit df5e3b5 with merge df71ca4…

To cancel the try build, run the command @bors try cancel.

Workflow: https://github.com/rust-lang/rust/actions/runs/37609720996

theemathas · 2026-10-08T05:54:50Z

@craterbot cancel

craterbot · 2026-10-08T05:54:54Z

🗑️ Experiment pr-133502-30 deleted!

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

lcnr · 2026-10-08T07:17:23Z

@craterbot run mode=check-only start=df71ca4bba430db14e784e45bb5259340e88b3ad+rustflags=-Znext-solver=coherence end=df71ca4bba430db14e784e45bb5259340e88b3ad crates=https://gist.githubusercontent.com/lcnr/0e2a09bb6b565ee9392c664a3c8cb47d/raw/a7aee74336eeb45df44563106cc3c9fc5930eece/failed-crates.txt p=6

craterbot · 2026-10-08T07:17:31Z

👌 Experiment pr-133502-30 created and queued.
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver) labels Nov 26, 2024

This comment has been minimized.

Sign in to view

compiler-errors force-pushed the rust4 branch from c3ef9cd to f631ca8 Compare November 27, 2024 04:03

This comment was marked as off-topic.

Sign in to view

This comment has been minimized.

Sign in to view

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 27, 2024

compiler-errors force-pushed the rust4 branch from f631ca8 to 6210ed3 Compare November 27, 2024 17:49

This comment has been minimized.

Sign in to view

compiler-errors force-pushed the rust4 branch from 6210ed3 to 8fa8f40 Compare November 27, 2024 20:15

This comment has been minimized.

Sign in to view

lcnr added 2 commits October 7, 2026 12:03

do not prefer trivially true candidates

06ec1ca

enable -Znext-solver by default

df5e3b5

lcnr mentioned this pull request Oct 7, 2026

do not prefer trivially true candidates with -Znext-solver #163928

Open

Conversation

lcnr commented Nov 26, 2024 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

crater

in-flight changes

Footnotes

Uh oh!

This comment has been minimized.

compiler-errors commented Nov 27, 2024

Uh oh!

bors commented Nov 27, 2024

Uh oh!

compiler-errors commented Nov 27, 2024

Uh oh!

This comment was marked as off-topic.

This comment has been minimized.

bors commented Nov 27, 2024

Uh oh!

bors commented Nov 27, 2024

Uh oh!

lqd commented Nov 27, 2024 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

compiler-errors commented Nov 27, 2024

Uh oh!

bors commented Nov 27, 2024

Uh oh!

This comment has been minimized.

This comment has been minimized.

bors commented Nov 27, 2024

Uh oh!

compiler-errors commented Nov 27, 2024

Uh oh!

bors commented Nov 27, 2024

Uh oh!

lqd commented Nov 27, 2024

Uh oh!

This comment has been minimized.

This comment has been minimized.

lcnr commented Oct 1, 2026

Uh oh!

craterbot commented Oct 1, 2026

Uh oh!

This comment has been minimized.

craterbot commented Oct 4, 2026

Uh oh!

craterbot commented Oct 6, 2026

Footnotes

Uh oh!

traviscross commented Oct 7, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

craterbot commented Oct 7, 2026

Uh oh!

traviscross commented Oct 7, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

craterbot commented Oct 7, 2026

Uh oh!

theemathas commented Oct 7, 2026

Uh oh!

craterbot commented Oct 7, 2026

Uh oh!

lcnr commented Oct 7, 2026

Uh oh!

craterbot commented Oct 7, 2026

Uh oh!

lcnr commented Oct 7, 2026

Uh oh!

lcnr commented Oct 7, 2026

Uh oh!

This comment has been minimized.

rust-bors Bot commented Oct 7, 2026

Uh oh!

lcnr commented Oct 7, 2026

Uh oh!

craterbot commented Oct 7, 2026

Uh oh!

lcnr commented Oct 7, 2026

Uh oh!

lcnr commented Nov 26, 2024 •

edited

Loading

lqd commented Nov 27, 2024 •

edited

Loading

traviscross commented Oct 7, 2026 •

edited

Loading

traviscross commented Oct 7, 2026 •

edited

Loading

rust-bors Bot commented Oct 7, 2026 •

edited

Loading