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

camsteffen · 2026-07-19T01:25:22Z

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

rustbot has assigned @folkertdev.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

Owners of files modified in this PR: compiler, types
compiler, types expanded to 74 candidates
Random selection from 17 candidates

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

I started on it and can push it in later. I have to change instantiate to use TypeFolder.

Oh, you can just skip_binder and keep the existing instantiation code

Well I've gone on a bit of a tangent now. I think the TypeFolder approach might be nice here. But slightly nicer if this is merged first: #159584. Though I don't mind if we decide TypeFolder is overkill for this PR.

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

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

This comment has been minimized.

Sign in to view

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

View reviewed changes

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

Nadrieril reviewed Jul 19, 2026

View reviewed changes

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

This comment has been minimized.

Sign in to view

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

This comment has been minimized.

Sign in to view

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

This comment has been minimized.

Sign in to view

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

Uh oh!

Uh oh!

Conversation

camsteffen commented Jul 19, 2026

Uh oh!

rustbot commented Jul 19, 2026

Uh oh!

rustbot commented Jul 19, 2026

Uh oh!

This comment has been minimized.

camsteffen commented Jul 19, 2026

Uh oh!

rustbot commented Jul 19, 2026

Uh oh!

Uh oh!

Nadrieril Jul 19, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Nadrieril Jul 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Nadrieril Jul 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Nadrieril Jul 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Nadrieril commented Jul 19, 2026

Uh oh!

Nadrieril commented Jul 19, 2026

Uh oh!

This comment has been minimized.

This comment has been minimized.

rust-bors Bot commented Jul 19, 2026

Uh oh!

This comment has been minimized.

rust-timer commented Jul 19, 2026

Overall result: ✅ improvements - no action needed

Uh oh!

Nadrieril commented Jul 19, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

6 participants

Nadrieril Jul 19, 2026 •

edited by rustbot

Loading

Nadrieril Jul 19, 2026 •

edited

Loading

Nadrieril Jul 19, 2026 •

edited

Loading

Nadrieril Jul 19, 2026 •

edited

Loading