normalize in relations, not generalize, when relating infer with alias by khyperia · Pull Request #160443 · rust-lang/rust

khyperia · 2026-08-03T14:27:16Z

This removes the wonky <?0 as Trait>::Assoc == ?0 handling in generalize, as the alias will be normalized before generalization gets invoked. (... in the new solver, the old solver is not touched).

My gut feeling is that change is potentially minorly perf-sensitive I think, I've had perf impacts here before, and we're slightly changing the way aliases are handled - especially invariant relations now generate an extra var then immediately do a equate_ty_vids_raw, it short-circuited before.

r? lcnr

rustbot · 2026-08-03T14:27:19Z

changes to the core type system

cc @lcnr

lcnr · 2026-08-04T06:49:19Z

+                    self.param_env(),
+                    ty::ProjectionPredicate { projection_term: alias.into(), term: new_var.into() },
+                )]);
+                self.tys(new_var, b)?;


that one is cool as it means for non-rigid eq non-rigid we emit two projection goals right away, for const aliases we currently do Projection(non-rigid, other-non-rigid). THinking whether creating a const infer var and then relating that would be better, even if for consts it's not strictly required as they are always equated, so no subtyping

View changes since the review

yeah mood. idk!

lcnr · 2026-08-04T06:49:30Z

@bors try @rust-timer queue

normalize in relations, not generalize, when relating infer with alias

lcnr · 2026-08-04T07:59:41Z

-        mut structurally_normalize: impl FnMut(Ty<'tcx>) -> Ty<'tcx>,
-        mut handle_field: impl FnMut(Ty<'tcx>, Option<VariantIdx>, FieldIdx, T) -> Ty<'tcx>,
+        // FIXME(#155345): This should only normalize when actually required.
+        mut structurally_normalize: impl FnMut(Unnormalized<'tcx, Ty<'tcx>>) -> Ty<'tcx>,


rename to normalize :> nothing structural about this anymore

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lcnr · 2026-08-04T08:00:00Z

-                }
-            }
-            Ok(a)
+            panic!("Non-rigid aliases should be handled in the caller of super_combine_tys")


Suggested change

panic!("Non-rigid aliases should be handled in the caller of super_combine_tys")

panic!("non-rigid aliases should be handled in the caller of super_combine_tys")

View changes since the review

rust-bors · 2026-08-04T08:59:40Z

☀️ Try build successful (CI)
Build commit: 0721d75 (0721d75742e22defdc7ffd82ae6395cc274dedd7)
Base parent: c9ff496 (c9ff496891c278ad660bc0ab85c1f0b72059464a)

lcnr

r=me with good perf

View changes since this review

rust-timer · 2026-08-04T09:41:19Z

Finished benchmarking commit (0721d75): comparison URL.

Overall result: ❌ regressions - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@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
Regressions ❌ (secondary)	1.0%	[1.0%, 1.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 0.1%, secondary -0.5%)

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

	mean	range	count
Regressions ❌ (primary)	2.5%	[0.4%, 4.5%]	2
Regressions ❌ (secondary)	1.5%	[0.4%, 2.6%]	2
Improvements ✅ (primary)	-0.5%	[-0.8%, -0.4%]	7
Improvements ✅ (secondary)	-0.7%	[-2.5%, -0.4%]	21
All ❌✅ (primary)	0.1%	[-0.8%, 4.5%]	9

Cycles

Results (primary -0.2%, secondary 0.3%)

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

	mean	range	count
Regressions ❌ (primary)	0.7%	[0.5%, 1.0%]	9
Regressions ❌ (secondary)	0.8%	[0.4%, 1.3%]	7
Improvements ✅ (primary)	-2.7%	[-6.3%, -0.8%]	3
Improvements ✅ (secondary)	-0.5%	[-0.8%, -0.4%]	5
All ❌✅ (primary)	-0.2%	[-6.3%, 1.0%]	12

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%]	1
All ❌✅ (primary)	-	-	0

Bootstrap: 489.838s -> 490.783s (0.19%)
Artifact size: 390.28 MiB -> 390.30 MiB (0.01%)

khyperia · 2026-08-04T11:26:30Z

@bors r=lcnr

rust-bors · 2026-08-04T11:26:34Z

📌 Commit 3dc2ef8 has been approved by lcnr

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 10. This pull request will be tested once the tree is reopened.

Reason for tree closure: manually handling queue due to backlog

…ns, r=lcnr normalize in relations, not generalize, when relating infer with alias This removes the wonky `<?0 as Trait>::Assoc == ?0` handling in generalize, as the alias will be normalized before generalization gets invoked. (... in the new solver, the old solver is not touched). My gut feeling is that change is potentially minorly perf-sensitive I think, I've had perf impacts here before, and we're slightly changing the way aliases are handled - especially invariant relations now generate an extra var then immediately do a `equate_ty_vids_raw`, it short-circuited before. r? lcnr

…uwer Rollup of 22 pull requests Successful merges: - #160426 (`rust-analyzer` subtree update) - #160372 (Derive the allocator used by tools from rustc's allocator) - #146882 (fully deprecate the legacy integral modules) - #158727 (std: use `readdir` on nearly all UNIX platforms) - #159727 (Various steps in moving away from the big reflection enum to reflection functions) - #160443 (normalize in relations, not generalize, when relating infer with alias) - #160457 (implement -Zllvm-target-feature) - #160480 (Single-pass ASCII lower/upper case conversion) - #160502 (Reduce number of miri tests executed on PR CI) - #157430 (std::random: use little-endian for reproducibility) - #158110 (fix macro attribute feature-gate span) - #159975 (Use real ThinVec in StmtDebugInfos) - #160001 (Suggest mutable method when iterating over binding) - #160024 (Fix mono reachability with no-op landing pads) - #160154 (Add regression test for HRTB associated type projection closure) - #160176 (No more `tests/ui/issues`!) - #160326 (Remove hidden_glob_reexports) - #160407 (Add regression tests for a number of ICEs and diagnostics issues labelled `E-needs-test`) - #160430 (bootstrap: Don't produce mutated/filtered PathSets during command-line matching) - #160472 (Minor fixes to `core::io` & `alloc::io` Documentation) - #160486 (Remove unused `FreeRegionsVisitor`) - #160496 (clarify non-determinism docs for algebraic operations) Failed merges: - #160501 (Add bootstrap CLI snapshot test for testing miri)

Rollup merge of #160443 - khyperia:move-normalize-to-relations, r=lcnr normalize in relations, not generalize, when relating infer with alias This removes the wonky `<?0 as Trait>::Assoc == ?0` handling in generalize, as the alias will be normalized before generalization gets invoked. (... in the new solver, the old solver is not touched). My gut feeling is that change is potentially minorly perf-sensitive I think, I've had perf impacts here before, and we're slightly changing the way aliases are handled - especially invariant relations now generate an extra var then immediately do a `equate_ty_vids_raw`, it short-circuited before. r? lcnr

…uwer Rollup of 22 pull requests Successful merges: - rust-lang/rust#160426 (`rust-analyzer` subtree update) - rust-lang/rust#160372 (Derive the allocator used by tools from rustc's allocator) - rust-lang/rust#146882 (fully deprecate the legacy integral modules) - rust-lang/rust#158727 (std: use `readdir` on nearly all UNIX platforms) - rust-lang/rust#159727 (Various steps in moving away from the big reflection enum to reflection functions) - rust-lang/rust#160443 (normalize in relations, not generalize, when relating infer with alias) - rust-lang/rust#160457 (implement -Zllvm-target-feature) - rust-lang/rust#160480 (Single-pass ASCII lower/upper case conversion) - rust-lang/rust#160502 (Reduce number of miri tests executed on PR CI) - rust-lang/rust#157430 (std::random: use little-endian for reproducibility) - rust-lang/rust#158110 (fix macro attribute feature-gate span) - rust-lang/rust#159975 (Use real ThinVec in StmtDebugInfos) - rust-lang/rust#160001 (Suggest mutable method when iterating over binding) - rust-lang/rust#160024 (Fix mono reachability with no-op landing pads) - rust-lang/rust#160154 (Add regression test for HRTB associated type projection closure) - rust-lang/rust#160176 (No more `tests/ui/issues`!) - rust-lang/rust#160326 (Remove hidden_glob_reexports) - rust-lang/rust#160407 (Add regression tests for a number of ICEs and diagnostics issues labelled `E-needs-test`) - rust-lang/rust#160430 (bootstrap: Don't produce mutated/filtered PathSets during command-line matching) - rust-lang/rust#160472 (Minor fixes to `core::io` & `alloc::io` Documentation) - rust-lang/rust#160486 (Remove unused `FreeRegionsVisitor`) - rust-lang/rust#160496 (clarify non-determinism docs for algebraic operations) Failed merges: - rust-lang/rust#160501 (Add bootstrap CLI snapshot test for testing miri)

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. labels Aug 3, 2026

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khyperia force-pushed the move-normalize-to-relations branch from 04d970b to 7ca8a78 Compare August 4, 2026 06:45

rustbot added the WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver) label Aug 4, 2026

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rust-bors Bot pushed a commit that referenced this pull request Aug 4, 2026

Auto merge of #160443 - khyperia:move-normalize-to-relations, r=<try>

0721d75

normalize in relations, not generalize, when relating infer with alias

khyperia force-pushed the move-normalize-to-relations branch from 7ca8a78 to ad05b23 Compare August 4, 2026 07:51

lcnr reviewed Aug 4, 2026

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khyperia added 2 commits August 4, 2026 10:18

normalize in relations, not generalize, when relating infer with alias

c316115

normalize the field ty in relate_type_and_user_type

3dc2ef8

khyperia force-pushed the move-normalize-to-relations branch from ad05b23 to 3dc2ef8 Compare August 4, 2026 08:46

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

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-Znext-solver: fix opaque type implied bounds unsoundness #160425

Closed

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 4, 2026

This was referenced Aug 4, 2026

Rollup of 14 pull requests #160507

Closed

Rollup of 22 pull requests #160517

Merged

rust-bors Bot merged commit 9dcaf05 into rust-lang:main Aug 5, 2026
13 checks passed

rustbot added this to the 1.99.0 milestone Aug 5, 2026

khyperia deleted the move-normalize-to-relations branch August 5, 2026 07:29

	panic!("Non-rigid aliases should be handled in the caller of super_combine_tys")
	panic!("non-rigid aliases should be handled in the caller of super_combine_tys")

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rust-timer commented Aug 4, 2026

Overall result: ❌ regressions - no action needed

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