`-Znext-solver` Less normalizes-to janks by ShoyuVanilla · Pull Request #156619 · rust-lang/rust

ShoyuVanilla · 2026-05-15T19:20:13Z

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cc rust-lang/trait-system-refactor-initiative#223 (comment)

r? lcnr

rustbot · 2026-05-15T19:20:17Z

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

changes to inspect_obligations.rs

cc @lcnr

This PR modifies tests/ui/issues/. If this PR is adding new tests to tests/ui/issues/,
please refrain from doing so, and instead add it to more descriptive subdirectories.

ShoyuVanilla · 2026-05-15T19:35:00Z

@bors try @rust-timer queue

`-Znext-solver` Less normalizes-to janks

ShoyuVanilla · 2026-05-15T19:46:09Z

I haven't done the nested goals' recursion depth part yet 😅 I'm gonna work on it if the overall design here pan out to be feasible

rust-bors · 2026-05-15T21:45:37Z

☀️ Try build successful (CI)
Build commit: d4c528b (d4c528b37c59bf04c41ddba6375584d284d1a9ba, parent: 88ba7fbe0a6eda36e0adbfd0482856f3784031b9)

rust-timer · 2026-05-15T23:03:40Z

Finished benchmarking commit (d4c528b): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.3%, 0.8%]	7
Regressions ❌ (secondary)	22.5%	[0.6%, 46.0%]	12
Improvements ✅ (primary)	-0.3%	[-0.7%, -0.1%]	20
Improvements ✅ (secondary)	-0.3%	[-0.6%, -0.2%]	29
All ❌✅ (primary)	-0.1%	[-0.7%, 0.8%]	27

Max RSS (memory usage)

Results (primary 1.5%, secondary 8.5%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	1.5%	[0.9%, 2.6%]	5
Regressions ❌ (secondary)	11.4%	[2.0%, 25.8%]	8
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-14.8%	[-14.8%, -14.8%]	1
All ❌✅ (primary)	1.5%	[0.9%, 2.6%]	5

Cycles

Results (secondary 26.9%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	26.9%	[17.5%, 41.5%]	9
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 510.626s -> 509.733s (-0.17%)
Artifact size: 398.07 MiB -> 398.06 MiB (-0.00%)

ShoyuVanilla · 2026-05-16T00:58:30Z

Oh, the perf regressions are insane 😅 I'll look into them

ShoyuVanilla · 2026-05-16T17:25:25Z

@bors try @rust-timer queue

`-Znext-solver` Less normalizes-to janks

rust-bors · 2026-05-16T19:35:04Z

☀️ Try build successful (CI)
Build commit: 52311d2 (52311d29eb5b4b58f67e481749703829fab93a19, parent: 35143615544ede08a47947901cd4a6b7c5ecd450)

rust-timer · 2026-05-16T20:16:10Z

Finished benchmarking commit (52311d2): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.8%	[0.2%, 1.2%]	8
Regressions ❌ (secondary)	26.5%	[0.1%, 45.5%]	10
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.1%]	23
Improvements ✅ (secondary)	-0.4%	[-0.8%, -0.2%]	29
All ❌✅ (primary)	0.0%	[-0.3%, 1.2%]	31

Max RSS (memory usage)

Results (primary 1.7%, secondary 8.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	1.7%	[1.0%, 2.8%]	6
Regressions ❌ (secondary)	11.3%	[2.1%, 25.8%]	8
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-14.7%	[-14.7%, -14.7%]	1
All ❌✅ (primary)	1.7%	[1.0%, 2.8%]	6

Cycles

Results (primary 2.3%, secondary 22.5%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	25.0%	[2.4%, 43.8%]	10
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.4%	[-2.4%, -2.4%]	1
All ❌✅ (primary)	2.3%	[2.3%, 2.3%]	1

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 513.812s -> 509.975s (-0.75%)
Artifact size: 398.43 MiB -> 400.31 MiB (0.47%)

ShoyuVanilla · 2026-05-28T15:44:20Z

If my observation is correct, this would fix the perf regression 🤔
@bors try @rust-timer queue

rust-timer · 2026-06-04T19:44:38Z

Command cannot be empty

rust-timer · 2026-06-04T20:40:38Z

Finished benchmarking commit (d3b5196): comparison URL.

Overall result: ❌✅ regressions and improvements - BENCHMARK(S) FAILED

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

❗ ❗ ❗ ❗ ❗
Warning ⚠️: The following benchmark(s) failed to build:

Job failure
typenum-1.18.0-new-solver

❗ ❗ ❗ ❗ ❗

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.4%, 0.4%]	1
Regressions ❌ (secondary)	23.0%	[0.0%, 30.7%]	4
Improvements ✅ (primary)	-0.2%	[-0.4%, -0.1%]	36
Improvements ✅ (secondary)	-0.7%	[-4.2%, -0.0%]	47
All ❌✅ (primary)	-0.2%	[-0.4%, 0.4%]	37

Max RSS (memory usage)

Results (primary 6.0%, secondary 7.6%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	6.0%	[4.7%, 7.8%]	4
Regressions ❌ (secondary)	11.9%	[0.9%, 25.9%]	8
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-9.5%	[-17.1%, -1.8%]	2
All ❌✅ (primary)	6.0%	[4.7%, 7.8%]	4

Cycles

Results (primary -2.3%, secondary -1.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.8%	[2.8%, 2.8%]	1
Regressions ❌ (secondary)	16.2%	[3.8%, 29.3%]	6
Improvements ✅ (primary)	-2.6%	[-3.9%, -1.2%]	18
Improvements ✅ (secondary)	-3.6%	[-14.7%, -1.9%]	41
All ❌✅ (primary)	-2.3%	[-3.9%, 2.8%]	19

Binary size

Results (primary -0.1%, secondary -0.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.0%]	51
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.0%]	24
All ❌✅ (primary)	-0.1%	[-0.1%, -0.0%]	51

Bootstrap: 515.26s -> 515.952s (0.13%)
Artifact size: 400.73 MiB -> 398.56 MiB (-0.54%)

ShoyuVanilla · 2026-06-05T01:44:39Z

Hmm, the failure looks sus 🤔
@rust-timer queue

ShoyuVanilla · 2026-06-05T02:08:55Z

@rust-timer build 8913f9a

rust-timer · 2026-06-05T02:08:58Z

Missing artifact for sha 8913f9a658da78d2cf104f0c53ad372fab4f00df (https://ci-artifacts.rust-lang.org/rustc-builds/8913f9a658da78d2cf104f0c53ad372fab4f00df/rustc-nightly-x86_64-unknown-linux-gnu.tar.xz); not built yet, try again later.

ShoyuVanilla · 2026-06-05T02:09:48Z

@rust-timer build d3b5196

rust-timer · 2026-06-05T02:09:51Z

Failed to enqueue some commit SHAs. Maybe they were already benchmarked?

ShoyuVanilla · 2026-06-05T05:56:35Z

Actually hangs due to the last commit 🤔

We had never stepped into recursive replacement with `AliasRelate` goals when replacing aliases because `AliasRelate` goals don't allow normalization

rustbot · 2026-06-05T14:59:55Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

ShoyuVanilla · 2026-06-05T15:02:06Z

@bors try @rust-timer queue

~~I expect perf regressions in typenum and that's another side effect of having denser nested goals within a given depth.~~
~~That crates depends on dropping candidates due to depth limits and takes longer with higher recursion limits~~

Edit) Oh, actually it wasn't 😅

`-Znext-solver` Less normalizes-to janks

rust-bors · 2026-06-05T17:13:17Z

☀️ Try build successful (CI)
Build commit: bf09da4 (bf09da45214f20549e2fc9522bc35357006a779f, parent: 39ec825c441918a4ae623a9b8840d1ccd446dcff)

rust-timer · 2026-06-05T18:24:13Z

Finished benchmarking commit (bf09da4): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.4%, 0.4%]	1
Regressions ❌ (secondary)	30.9%	[30.9%, 31.0%]	3
Improvements ✅ (primary)	-0.2%	[-0.5%, -0.1%]	40
Improvements ✅ (secondary)	-1.0%	[-5.5%, -0.1%]	49
All ❌✅ (primary)	-0.2%	[-0.5%, 0.4%]	41

Max RSS (memory usage)

Results (primary 2.4%, secondary 6.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.4%	[2.4%, 2.4%]	1
Regressions ❌ (secondary)	13.7%	[0.8%, 25.8%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.5%	[-17.1%, -1.4%]	4
All ❌✅ (primary)	2.4%	[2.4%, 2.4%]	1

Cycles

Results (secondary 3.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	29.2%	[28.9%, 29.5%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.6%	[-6.0%, -2.1%]	11
All ❌✅ (primary)	-	-	0

Binary size

Results (secondary -0.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	3
All ❌✅ (primary)	-	-	0

Bootstrap: 514.669s -> 514.548s (-0.02%)
Artifact size: 400.66 MiB -> 400.59 MiB (-0.02%)

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 May 15, 2026

rustbot assigned lcnr May 15, 2026

ShoyuVanilla mentioned this pull request May 15, 2026

-Znext-solver Remove special handling of NormalizesTo goal #154433

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label May 15, 2026

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rust-bors Bot pushed a commit that referenced this pull request May 15, 2026

Auto merge of #156619 - ShoyuVanilla:less-normalizes-to-jank, r=<try>

d4c528b

`-Znext-solver` Less normalizes-to janks

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rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels May 15, 2026

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label May 16, 2026

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rust-bors Bot pushed a commit that referenced this pull request May 16, 2026

Auto merge of #156619 - ShoyuVanilla:less-normalizes-to-jank, r=<try>

52311d2

`-Znext-solver` Less normalizes-to janks

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label May 16, 2026

ShoyuVanilla force-pushed the less-normalizes-to-jank branch from 6bd6498 to 5927eca Compare May 28, 2026 15:43

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 4, 2026

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 5, 2026

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ShoyuVanilla added 8 commits June 5, 2026 23:36

Use ProjectionPredicate for normalizations

8eb22ae

Move files

7c8a28a

Handle non-trait projections

a39f8c5

Handle trait projections

3a69482

Bless tests

77f247f

Reduce might be redundant normalizes-to nested goal evaluations

561c4e1

perf: Do not recursively replace aliases in predicates

d2fb6b2

We had never stepped into recursive replacement with `AliasRelate` goals when replacing aliases because `AliasRelate` goals don't allow normalization

Do not increase depth when evaluating nested goals of normalizes-to

5c1e975

ShoyuVanilla force-pushed the less-normalizes-to-jank branch from 8913f9a to 5c1e975 Compare June 5, 2026 14:59

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rust-bors Bot pushed a commit that referenced this pull request Jun 5, 2026

Auto merge of #156619 - ShoyuVanilla:less-normalizes-to-jank, r=<try>

bf09da4

`-Znext-solver` Less normalizes-to janks

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jun 5, 2026

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rust-timer commented May 15, 2026

Overall result: ❌✅ regressions and improvements - please read:

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Overall result: ❌✅ regressions and improvements - please read:

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Overall result: ❌✅ regressions and improvements - BENCHMARK(S) FAILED

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Overall result: ❌✅ regressions and improvements - please read:

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