Use query for Variant InhabitedPredicate by camsteffen · Pull Request #159541 · rust-lang/rust

camsteffen · 2026-07-19T01:25:22Z

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It looks like there may be some benefit from caching.

rustbot · 2026-07-19T01:25:25Z

Some changes occurred in exhaustiveness checking

cc @Nadrieril

Some changes occurred in match checking

cc @Nadrieril

rustbot · 2026-07-19T01:25:27Z

r? @folkertdev

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camsteffen · 2026-07-19T02:21:30Z

@rustbot author

rustbot · 2026-07-19T02:21:34Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

Nadrieril · 2026-07-19T09:45:31Z

+            let adt = tcx.adt_def(def_id);
+            variant_inhabited_predicate(tcx, adt.non_enum_variant())
+        }
+        DefKind::Variant => {


Feels unexpected to me that a Variant would be an admissible input for a function called something_adt; this deserves an extra comment imo

View changes since the review

I think I'd prefer to rename the query to inhabited_predicate_for_def and have it return an EarlyBinder<InhabitedPredicate>

I did the rename but still looking into EarlyBinder. Maybe that can be a separate PR?

It's just a wrapper that says "btw, the value you get from this query needs to be passed generic arguments", it's what we use for the output of most queries that get type-related information about a DefId, just as a reminder

Also happy to leave that, it's not crucial

Since both are potentially performance-affecting, let's move to TypeFolder later?

Okay how bout we merge this as is and I'll add EarlyBinder with or without TypeFolder separately.

makes a lot of sense yes!

Oh it seems I can't just use EarlyBinder by itself because EarlyBinder::bind requires TypeFoldable.

Also I just found out that TypeFoldable requires TypeVisitable, so I don't think that's practical.

oh! well, let's just leave things like this then

Nadrieril · 2026-07-19T09:51:03Z

r? me

I left a few comments as I was passing by but the most important is the perf run ofc

Nadrieril · 2026-07-19T15:23:33Z

@bors try @rust-timer queue

Use query for Variant InhabitedPredicate

rust-bors · 2026-07-19T17:37:43Z

☀️ Try build successful (CI)
Build commit: 2421524 (242152418e59c924e48149b9736f96f695f67745)
Base parent: 234c31c (234c31cd674e11703f15d290cba7ff81dfe8b4b8)

rust-timer · 2026-07-19T18:17:21Z

Finished benchmarking commit (2421524): comparison URL.

Overall result: ✅ improvements - no action needed

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.

@bors rollup=never rustc-perf
@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)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.4%, -0.3%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.3%	[-0.4%, -0.3%]	2

Max RSS (memory usage)

Results (primary 0.9%, 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)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	6.5%	[5.1%, 8.0%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.5%	[-4.1%, -2.7%]	4
All ❌✅ (primary)	0.9%	[0.9%, 0.9%]	1

Cycles

Results (primary 2.1%, secondary -2.5%)

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

	mean	range	count
Regressions ❌ (primary)	2.1%	[2.1%, 2.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.5%	[-2.8%, -2.1%]	2
All ❌✅ (primary)	2.1%	[2.1%, 2.1%]	1

Binary size

Results (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
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	3
All ❌✅ (primary)	-	-	0

Bootstrap: 488.235s -> 485.708s (-0.52%)
Artifact size: 392.45 MiB -> 391.72 MiB (-0.19%)

Nadrieril · 2026-07-19T20:28:42Z

Small but with a green tendency, I say why not

Nadrieril · 2026-07-20T13:06:01Z

@bors r+

rust-bors · 2026-07-20T13:06:04Z

📌 Commit 553f6c8 has been approved by Nadrieril

It is now in the queue for this repository.

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 Jul 19, 2026

rustbot assigned folkertdev Jul 19, 2026

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rustbot 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 Jul 19, 2026

Nadrieril reviewed Jul 19, 2026

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Comment thread compiler/rustc_mir_build/src/thir/pattern/check_match.rs

Nadrieril reviewed Jul 19, 2026

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rustbot assigned Nadrieril and unassigned folkertdev Jul 19, 2026

Use query for Variant InhabitedPredicate

553f6c8

camsteffen force-pushed the inhabited-variant-query branch from 2c18d60 to 553f6c8 Compare July 19, 2026 12:44

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 19, 2026

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rust-bors Bot pushed a commit that referenced this pull request Jul 19, 2026

Auto merge of #159541 - camsteffen:inhabited-variant-query, r=<try>

2421524

Use query for Variant InhabitedPredicate

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 19, 2026

rust-bors Bot added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Jul 20, 2026

rust-bors Bot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jul 20, 2026

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Nadrieril commented Jul 19, 2026

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rust-timer commented Jul 19, 2026

Overall result: ✅ improvements - no action needed

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