Call `features_query` fewer times in `smart_resolve_macro_path` by fmease · Pull Request #155155 · rust-lang/rust

fmease · 2026-04-11T14:56:55Z

fmease · 2026-04-11T14:57:10Z

Call `features_query` fewer times in `smart_resolve_macro_path`

fmease · 2026-04-11T14:58:58Z

compiler/rustc_resolve/src/macros.rs

-                .collect::<Vec<_>>();
-            let typo = find_best_match_for_name(&candidates, attribute.ident.name, Some(5))
+            let stable_diagnostic_attributes: Vec<_> =
+                [sym::on_unimplemented, sym::do_not_recommend, sym::on_move]


View changes since the review

(preexisting) on_move "stable"? That's news to me. Should probably be gated as well. Or is it gated elsewhere?

I remember that attribute being gated, so it's gate is probably elsewhere

@fmease the gates are in attribute parsing, all three unstable diagnostic attrs have a check like

rust/compiler/rustc_attr_parsing/src/attributes/diagnostic/on_unknown.rs

Lines 20 to 22 in 5f36a7f

if !cx.features().diagnostic_on_unknown() {

return;

}

The checks in rustc_resolve here are just for typo suggestions. but on_move was merged in between the creation and merge of #152901, that's probably why it's accidentally there.

Ah, thanks, I see, obvious in hindsight

Can you give on_move the same feature check as on_const/on_unknown below? Thanks!

fmease · 2026-04-11T15:01:16Z

compiler/rustc_resolve/src/macros.rs

-            (sym::on_unknown, self.tcx.features().diagnostic_on_unknown()),
-        ];
-
        if res == Res::NonMacroAttr(NonMacroAttrKind::Tool)


View changes since the review

(preexisting) Kinda odd that we perform this check here instead of over in rustc_attr_parsing. Of course, this check has existed long before rustc_attr_parsing was introduced but now we should have better infrastructure in place.

Note that I'm not super familiar with the "low-level entry point" of the new attribute parsing infrastructure, so I don't know if there's a good reason why this check happens here.

Yeah I still have plans to move feature gating to the new attribute parsing Infrastructure, but that is nicer to do after the lint attributes are ported again

rust-bors · 2026-04-11T17:06:48Z

☀️ Try build successful (CI)
Build commit: bbece70 (bbece7035e94319094008a1fedee27ce316f74d3, parent: 5f36a7f8072e835d73d9e1f7ab8a2134ac7352dc)

mejrs · 2026-04-11T17:06:15Z

compiler/rustc_resolve/src/macros.rs

-                .collect::<Vec<_>>();
-            let typo = find_best_match_for_name(&candidates, attribute.ident.name, Some(5))
+            let stable_diagnostic_attributes: Vec<_> =
+                [sym::on_unimplemented, sym::do_not_recommend, sym::on_move]


Can you give on_move the same feature check as on_const/on_unknown below? Thanks!

mejrs · 2026-04-11T17:08:39Z

compiler/rustc_resolve/src/macros.rs

+                let typo = find_best_match_for_name(
+                    &stable_diagnostic_attributes,
+                    attribute.ident.name,
+                    Some(5),


View changes since the review

I just realized that on_move and on_const are really similar to each other (their edit distance is 4), so this should probably be

Suggested change

Some(5),

None,

rust-timer · 2026-04-11T18:10:48Z

Finished benchmarking commit (bbece70): comparison URL.

Overall result: no relevant changes - 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
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

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

Max RSS (memory usage)

Results (secondary -1.6%)

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)	-1.6%	[-1.6%, -1.6%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 3.0%)

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)	3.0%	[3.0%, 3.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 0.0%, 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)	0.0%	[0.0%, 0.0%]	6
Regressions ❌ (secondary)	0.1%	[0.1%, 0.1%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.0%]	6

Bootstrap: 491.284s -> 489.863s (-0.29%)
Artifact size: 394.15 MiB -> 394.15 MiB (-0.00%)

fmease · 2026-04-11T18:40:25Z

Hmm, too bad.

mejrs · 2026-04-11T19:13:27Z

ImportData went from 216 to 352 bytes, could that be it? I have a PR that boxes it, #155167

fmease · 2026-04-11T19:22:33Z

I guess I'll repurpose this PR as a ~cleanup one ^^ once I've applied mejrs's suggestions.

Call features_query fewer times in smart_resolve_macro_path

45655c7

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 11, 2026

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rust-bors bot pushed a commit that referenced this pull request Apr 11, 2026

Auto merge of #155155 - fmease:diag-attr-perf, r=<try>

bbece70

Call `features_query` fewer times in `smart_resolve_macro_path`

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Apr 11, 2026

fmease commented Apr 11, 2026

View reviewed changes

fmease mentioned this pull request Apr 11, 2026

Introduce a #[diagnostic::on_unknown] attribute #152901

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mejrs reviewed Apr 11, 2026

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Apr 11, 2026

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rust-timer commented Apr 11, 2026

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fmease Apr 11, 2026 •

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