Move `check_rustc_pub_transparent` into the attribute parser by obeis · Pull Request #158496 · rust-lang/rust

obeis · 2026-06-27T18:34:48Z

Verify the #[repr(transparent)] requirement in RustcPubTransparentParser::finalize_check, replacing check_rustc_pub_transparent in rustc_passes.

r? @JonathanBrouwer

rustbot · 2026-06-27T18:34:51Z

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann, @JonathanBrouwer

rustbot · 2026-06-27T18:57:12Z

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.

JonathanBrouwer · 2026-06-27T19:32:32Z

+            .filter_map(|attr| attr.args.as_ref()?.as_list())
+            .flat_map(|list| list.mixed())
+            .filter_map(|item| item.meta_item())
+            .any(|meta| meta.path().word_is(sym::transparent))


Hmmm I don't really like that we're duplicating some of the Repr parsing logic here.
How hard would it be to get access to the parsed repr attribute here?

View changes since the review

I see two ways to handle this:

Extract a helper function:that holds the iteration logic currently inlined in lint_helpers.rs. I'd move it next to the repr parser in repr.rs so the logic lives in one place.

Add the parsed attributes to FinalizeContext, so we can match on AttributeKind::Repr directly instead of re-walking the raw attribute args.
I think the second approach is much cleaner, since it avoids re-parsing entirely.

I prefer #2 strongly but the parsed attributes are only available after finalization, I think it's possible to work around that tho

rustbot · 2026-06-27T19:32:38Z

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

the parsed attributes of an item were only fully populated after all finalizers had run, so `finalize_check` (run during finalization) could only inspect attribute *paths* via `FinalizeContext::all_attrs`, not the parsed `AttributeKind`s. split finalization into two passes: first run all finalizers to produce the parsed attributes, then run the cross-attribute checks. The checks are deferred via a new `AttributeParser::deferred_finalize_check`, and can now inspect the fully parsed attributes through a new `FinalizeContext::parsed_attrs` field.

the check that `#[rustc_pub_transparent]` is only applied to `#[repr(transparent)]` types needs to see the parsed `Repr` attribute, so it now lives in `RustcPubTransparentParser::finalize_check`, using the freshly available `FinalizeContext::parsed_attrs`.

JonathanBrouwer · 2026-07-10T09:57:38Z

@bors try @rust-timer queue

Move `check_rustc_pub_transparent` into the attribute parser

JonathanBrouwer

Sorry for the delay reviewing this, I've been moving :)

View changes since this review

JonathanBrouwer · 2026-07-10T09:57:20Z

+        // inspect the fully parsed attributes via `FinalizeContext::parsed_attrs`.
+        for (check, attr_span) in deferred_checks {
+            check(
+                &FinalizeContext {


I think it doesn't make sense for check to use the FinalizeContext.
Because of this choice, in the code above you have to lie and give an &[].

Can you make a new context for this?

I added the new context.

rust-bors · 2026-07-10T12:05:48Z

☀️ Try build successful (CI)
Build commit: 1e998ba (1e998ba5d10376d82582f8f94a902680636a6f0b)
Base parent: 3ead112 (3ead112e67f8feb4d6b09e12f1b5d83b87698961)

rust-timer · 2026-07-10T12:46:33Z

Finished benchmarking commit (1e998ba): 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
Regressions ❌ (secondary)	0.1%	[0.0%, 0.2%]	8
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.2%]	2
Improvements ✅ (secondary)	-0.0%	[-0.1%, -0.0%]	3
All ❌✅ (primary)	-0.2%	[-0.2%, -0.2%]	2

Max RSS (memory usage)

Results (primary 0.8%, secondary 2.1%)

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

	mean	range	count
Regressions ❌ (primary)	0.8%	[0.6%, 1.0%]	2
Regressions ❌ (secondary)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.8%	[0.6%, 1.0%]	2

Cycles

Results (primary 57.6%, secondary -0.6%)

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

	mean	range	count
Regressions ❌ (primary)	57.6%	[57.6%, 57.6%]	1
Regressions ❌ (secondary)	3.2%	[2.5%, 4.0%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.7%	[-5.7%, -1.5%]	7
All ❌✅ (primary)	57.6%	[57.6%, 57.6%]	1

Binary size

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

Bootstrap: 490.513s -> 491.871s (0.28%)
Artifact size: 389.99 MiB -> 389.40 MiB (-0.15%)

JonathanBrouwer · 2026-07-10T14:00:59Z

Perf result looks like a lot of noise, the libc improvements might be real but no clue why they would improve?

rust-bors · 2026-07-17T19:57:42Z

☔ The latest upstream changes (presumably #159444) made this pull request unmergeable. Please resolve the merge conflicts by rebasing.

rustbot added A-attributes Area: Attributes (`#[…]`, `#![…]`) 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 Jun 27, 2026

rustbot assigned JonathanBrouwer Jun 27, 2026

obeis force-pushed the move-check-rustc-pub-transparen branch from 4756680 to 36e0436 Compare June 27, 2026 18:57

obeis force-pushed the move-check-rustc-pub-transparen branch from 36e0436 to a5834bd Compare June 27, 2026 19:19

JonathanBrouwer requested changes Jun 27, 2026

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rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 27, 2026

rustbot added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jun 27, 2026

JonathanBrouwer mentioned this pull request Jun 27, 2026

Reduce the size of check_attrs.rs and move as much as possible into the attribute parsers. #153101

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obeis added 2 commits June 28, 2026 14:52

obeis force-pushed the move-check-rustc-pub-transparen branch from a5834bd to b6b2e9c Compare June 28, 2026 17:31

obeis requested a review from JonathanBrouwer June 28, 2026 17:33

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 28, 2026

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rust-bors Bot pushed a commit that referenced this pull request Jul 10, 2026

Auto merge of #158496 - obeis:move-check-rustc-pub-transparen, r=<try>

1e998ba

Move `check_rustc_pub_transparent` into the attribute parser

JonathanBrouwer requested changes Jul 10, 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 10, 2026

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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 Jul 10, 2026

Add FinalizeCheckContext for attribute parser

5e9b7ee

obeis requested a review from JonathanBrouwer July 10, 2026 18:42

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 10, 2026

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rust-timer commented Jul 10, 2026

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

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