rewrite outlives placeholder constraints to outlives static when handling opaque types #147566

BoxyUwU · 2025-10-10T19:04:20Z

Fixes #147529

r? lcnr

see test comment

compiler/rustc_borrowck/src/region_infer/opaque_types/mod.rs

lcnr · 2025-10-13T07:35:18Z

@bors try @rust-timer queue

…<try> rewrite outlives placeholder constraints to outlives static when handling opaque types

lcnr · 2025-10-13T07:38:38Z

compiler/rustc_borrowck/src/region_infer/opaque_types/region_ctxt.rs

    ) -> RegionCtxt<'a, 'tcx> {
+        let mut outlives_constraints = constraints.outlives_constraints.clone();
        let universal_regions = &universal_region_relations.universal_regions;
        let (definitions, _has_placeholders) = region_definitions(infcx, universal_regions);


u're ignoring _has_placeholders?

figured if perf was OK there'd be no point in complicating the flow of the logic with a perf opt based on whether there were placeholders or not

lcnr

some small nits, r=me on the change

please also add a test to the same file which uses a for<'a> T: 'a where bound instead of the for<'a> T: Outlives<'a>.

That didn't regress but feels like the same pattern 😁

View changes since this review

compiler/rustc_borrowck/src/region_infer/opaque_types/mod.rs

rust-bors · 2025-10-13T09:47:06Z

☀️ Try build successful (CI)
Build commit: 53d5e63 (53d5e639745f490c8f6ff3e162f43422163e408b, parent: 36e4f5d1fe1d63953a5bf1758ce2b64172623e2e)

rust-timer · 2025-10-13T10:57:26Z

Finished benchmarking commit (53d5e63): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

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

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

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Cycles

Results (secondary -2.4%)

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)	2.4%	[2.4%, 2.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.4%	[-4.6%, -2.3%]	5
All ❌✅ (primary)	-	-	0

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Bootstrap: 473.739s -> 473.454s (-0.06%)
Artifact size: 388.11 MiB -> 388.12 MiB (0.00%)

…aceholders

lcnr · 2025-10-13T14:36:28Z

@bors r+ rollup

bors · 2025-10-13T14:36:31Z

📌 Commit 30bedc7 has been approved by lcnr

It is now in the queue for this repository.

…utlives, r=lcnr rewrite outlives placeholder constraints to outlives static when handling opaque types Fixes rust-lang#147529 r? lcnr see test comment

Rollup of 7 pull requests Successful merges: - #144266 (Supress swapping lhs and rhs in equality suggestion in extern macro ) - #147471 (Assert that non-extended temporaries and `super let` bindings have scopes) - #147533 (Renumber return local after state transform) - #147566 (rewrite outlives placeholder constraints to outlives static when handling opaque types) - #147613 (Make logging filters work again by moving EnvFilter into its own layer) - #147615 (reduce calls to attr.span() in old doc attr parsing) - #147636 (miri subtree update) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #147566 - BoxyUwU:opaque_types_placeholder_outlives, r=lcnr rewrite outlives placeholder constraints to outlives static when handling opaque types Fixes #147529 r? lcnr see test comment

Rollup of 7 pull requests Successful merges: - rust-lang/rust#144266 (Supress swapping lhs and rhs in equality suggestion in extern macro ) - rust-lang/rust#147471 (Assert that non-extended temporaries and `super let` bindings have scopes) - rust-lang/rust#147533 (Renumber return local after state transform) - rust-lang/rust#147566 (rewrite outlives placeholder constraints to outlives static when handling opaque types) - rust-lang/rust#147613 (Make logging filters work again by moving EnvFilter into its own layer) - rust-lang/rust#147615 (reduce calls to attr.span() in old doc attr parsing) - rust-lang/rust#147636 (miri subtree update) r? `@ghost` `@rustbot` modify labels: rollup

apiraino · 2025-10-16T14:11:27Z

Beta backport approved as per compiler team on Zulip. A backport PR will be authored by the release team at the end of the current development cycle. Backport labels handled by them.

@rustbot label +beta-accepted

[beta] backports - Change int-to-ptr transmute lowering back to inttoptr #147541 - rewrite outlives placeholder constraints to outlives static when handling opaque types #147566 - GVN: Invalidate derefs at loop headers #147607 r? cuviper

rustbot assigned lcnr Oct 10, 2025

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. beta-nominated Nominated for backporting to the compiler in the beta channel. labels Oct 10, 2025