Detect more `cfg`d out items in resolution errors #129183

estebank · 2024-08-17T05:45:54Z

Use a visitor to collect all items (including those nested) that were stripped behind a cfg condition.

error[E0425]: cannot find function `f` in this scope
  --> $DIR/nested-cfg-attrs.rs:4:13
   |
LL | fn main() { f() }
   |             ^ not found in this scope
   |
note: found an item that was configured out
  --> $DIR/nested-cfg-attrs.rs:2:4
   |
LL | fn f() {}
   |    ^
note: the item is gated here
  --> $DIR/nested-cfg-attrs.rs:1:35
   |
LL | #[cfg_attr(all(), cfg_attr(all(), cfg(FALSE)))]
   |                                   ^^^^^^^^^^

rustbot · 2024-08-17T05:46:03Z

r? @cjgillot

rustbot has assigned @cjgillot.
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compiler/rustc_expand/src/expand.rs

Noratrieb · 2024-08-17T11:47:47Z

tests/ui/cfg/diagnostics-reexport.rs

@@ -1,7 +1,7 @@
 pub mod inner {
-    #[cfg(FALSE)]
+    #[cfg(FALSE)] //~ NOTE the item is gated here


I don't think this is correct? no one ever references this item.

This is because uwu under inner::gone now gets included for inner (because gone is cfgd out) when trying to access inner::uwu. I believe this is the right thing to do. If the user had written inner::gone::uwu, the output is:

error[E0433]: failed to resolve: could not find `gone` in `inner` --> tests/ui/cfg/diagnostics-reexport.rs:38:12 | 38 | inner::gone::uwu(); //~ ERROR cannot find function | ^^^^ could not find `gone` in `inner` | note: found an item that was configured out --> tests/ui/cfg/diagnostics-reexport.rs:3:9 | 3 | mod gone { | ^^^^ note: the item is gated here --> tests/ui/cfg/diagnostics-reexport.rs:2:5 | 2 | #[cfg(FALSE)] //~ NOTE the item is gated here | ^^^^^^^^^^^^^

but if it is inner::gon::uwu then the output is

error[E0433]: failed to resolve: could not find `gon` in `inner` --> tests/ui/cfg/diagnostics-reexport.rs:38:12 | 38 | inner::gon::uwu(); //~ ERROR cannot find function | ^^^ could not find `gon` in `inner`

We might actually want to still search for cfgd out items both with levenshtein distance (but the signal there is much weaker) and by looking at the very last path segment (to find the cfgd out uwu).

I tend to agree with @Noratrieb: the user wrote inner::uwu, which refers to the use super::uwu below, which already failed to resolve without suggesting gone. Either both suggest gone::uwu, or none of them.

tests/ui/cfg/diagnostics-same-crate.rs

petrochenkov · 2024-08-20T16:30:38Z

We are doing more work on a good path here.
@bors try @rust-timer queue

Detect more `cfg`d out items in resolution errors Use a visitor to collect *all* items (including those nested) that were stripped behind a `cfg` condition. ``` error[E0425]: cannot find function `f` in this scope --> $DIR/nested-cfg-attrs.rs:4:13 | LL | fn main() { f() } | ^ not found in this scope | note: found an item that was configured out --> $DIR/nested-cfg-attrs.rs:2:4 | LL | fn f() {} | ^ note: the item is gated here --> $DIR/nested-cfg-attrs.rs:1:35 | LL | #[cfg_attr(all(), cfg_attr(all(), cfg(FALSE)))] | ^^^^^^^^^^ ```

bors · 2024-08-20T16:31:51Z

⌛ Trying commit 95c2b46 with merge 623e6c7...

bors · 2024-08-20T18:30:37Z

☀️ Try build successful - checks-actions
Build commit: 623e6c7 (623e6c7b5c223cff0a4b75919463e800e0563a50)

rust-timer · 2024-08-20T19:46:57Z

Finished benchmarking commit (623e6c7): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.2%, 0.2%]	1
Regressions ❌ (secondary)	1.9%	[1.9%, 1.9%]	1
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.2%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.1%	[-0.3%, 0.2%]	3

Max RSS (memory usage)

Results (primary 2.6%, secondary 1.5%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.6%	[1.8%, 3.3%]	3
Regressions ❌ (secondary)	3.1%	[1.7%, 4.3%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.8%	[-4.8%, -4.8%]	1
All ❌✅ (primary)	2.6%	[1.8%, 3.3%]	3

Cycles

Results (secondary -2.9%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.9%	[-3.1%, -2.6%]	6
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 0.1%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.1%	[0.0%, 0.4%]	83
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.4%]	83

Bootstrap: 749.153s -> 748.829s (-0.04%)
Artifact size: 338.89 MiB -> 338.83 MiB (-0.02%)

estebank · 2024-08-22T16:56:55Z

It might make sense to limit the visitor to two levels of nesting at most, as a way to attempt to reduce the impact on crates that have large modules cfgd out. I suspect that we might not have any test case of a large crate in that configuration, and that's why we're not seeing more effects from this change.

estebank · 2024-08-28T23:35:21Z

@bors try @rust-timer queue

Detect more `cfg`d out items in resolution errors Use a visitor to collect *all* items (including those nested) that were stripped behind a `cfg` condition. ``` error[E0425]: cannot find function `f` in this scope --> $DIR/nested-cfg-attrs.rs:4:13 | LL | fn main() { f() } | ^ not found in this scope | note: found an item that was configured out --> $DIR/nested-cfg-attrs.rs:2:4 | LL | fn f() {} | ^ note: the item is gated here --> $DIR/nested-cfg-attrs.rs:1:35 | LL | #[cfg_attr(all(), cfg_attr(all(), cfg(FALSE)))] | ^^^^^^^^^^ ```

bors · 2024-08-28T23:36:32Z

⌛ Trying commit 0e22c73 with merge 811a696...

bors · 2024-08-29T01:31:15Z

☀️ Try build successful - checks-actions
Build commit: 811a696 (811a69609bf7d38bbab02fa8f4d3b4cb98802f24)

rust-timer · 2024-08-29T03:55:45Z

Finished benchmarking commit (811a696): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.2%, 0.3%]	4
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	1
All ❌✅ (primary)	0.2%	[0.2%, 0.3%]	4

Max RSS (memory usage)

Results (primary 1.6%, secondary 2.3%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.6%	[0.6%, 2.6%]	4
Regressions ❌ (secondary)	2.3%	[2.1%, 2.7%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.6%	[0.6%, 2.6%]	4

Cycles

Results (secondary -2.9%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.9%	[-3.4%, -2.6%]	14
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 0.1%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.1%	[0.0%, 0.5%]	83
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.5%]	83

Bootstrap: 753.9s -> 754.227s (0.04%)
Artifact size: 338.87 MiB -> 339.03 MiB (0.05%)

apiraino · 2025-04-08T10:16:14Z

@Noratrieb @Urgau given you left some comments, do you have capacity to help reviewing here? I am going to reroll the review assignment but feel free to take it 🙂 thanks

r? compiler

davidtwco · 2025-04-16T15:09:00Z

With previous reviews, this looks good to me, r=me after rebase.

Use a visitor to collect *all* items (including those nested) that were stripped behind a `cfg` condition. ``` error[E0425]: cannot find function `f` in this scope --> $DIR/nested-cfg-attrs.rs:4:13 | LL | fn main() { f() } | ^ not found in this scope | note: found an item that was configured out --> $DIR/nested-cfg-attrs.rs:2:4 | LL | fn f() {} | ^ note: the item is gated here --> $DIR/nested-cfg-attrs.rs:1:35 | LL | #[cfg_attr(all(), cfg_attr(all(), cfg(FALSE)))] | ^^^^^^^^^^ ```

``` error[E0433]: failed to resolve: could not find `doesnt_exist` in `inner` --> $DIR/diagnostics-cross-crate.rs:18:23 | LL | cfged_out::inner::doesnt_exist::hello(); | ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner` | note: found an item that was configured out --> $DIR/auxiliary/cfged_out.rs:6:13 | LL | #[cfg(false)] | ----- the item is gated here LL | pub mod doesnt_exist { | ^^^^^^^^^^^^ ```

estebank · 2025-08-02T01:57:57Z

@bors r=davidtwco

bors · 2025-08-02T01:57:59Z

📌 Commit 4b24c4b has been approved by davidtwco

It is now in the queue for this repository.

bors · 2025-08-02T05:09:34Z

⌛ Testing commit 4b24c4b with merge 889701d...

bors · 2025-08-02T08:11:34Z

☀️ Test successful - checks-actions
Approved by: davidtwco
Pushing 889701d to master...

github-actions · 2025-08-02T08:15:07Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing c23f07d (parent) -> 889701d (this PR)

Test differences

Show 12 test diffs

12 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 889701db1ff614160314734fe4138c2f820a95bb --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

x86_64-apple-2: 5441.6s -> 3689.5s (-32.2%)
dist-aarch64-apple: 5605.8s -> 7278.2s (29.8%)
x86_64-apple-1: 9579.5s -> 7060.2s (-26.3%)
pr-check-1: 1774.1s -> 1483.2s (-16.4%)
aarch64-gnu-llvm-19-1: 3905.4s -> 3305.3s (-15.4%)
x86_64-rust-for-linux: 2971.1s -> 2579.4s (-13.2%)
pr-check-2: 2749.8s -> 2389.9s (-13.1%)
dist-apple-various: 4167.4s -> 4582.7s (10.0%)
x86_64-gnu-llvm-19-2: 6253.5s -> 5631.0s (-10.0%)
aarch64-gnu-llvm-19-2: 2393.7s -> 2162.4s (-9.7%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2025-08-02T09:22:26Z

Finished benchmarking commit (889701d): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -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)	1.3%	[1.3%, 1.3%]	1
Regressions ❌ (secondary)	1.3%	[1.3%, 1.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.3%	[1.3%, 1.3%]	1

Max RSS (memory usage)

Results (primary 6.9%)

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

	mean	range	count
Regressions ❌ (primary)	6.9%	[6.9%, 6.9%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	6.9%	[6.9%, 6.9%]	1

Cycles

Results (secondary -3.5%)

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)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-9.1%	[-9.1%, -9.1%]	1
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 468.795s -> 467.526s (-0.27%)
Artifact size: 376.84 MiB -> 376.82 MiB (-0.01%)

rustbot assigned cjgillot Aug 17, 2024

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 Aug 17, 2024

Urgau reviewed Aug 17, 2024

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compiler/rustc_expand/src/expand.rs Outdated Show resolved Hide resolved

petrochenkov self-assigned this Aug 17, 2024

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estebank force-pushed the cfg-visitor branch from 1390498 to 95c2b46 Compare August 17, 2024 19:57

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estebank force-pushed the cfg-visitor branch from 95c2b46 to 0e22c73 Compare August 28, 2024 23:35

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estebank force-pushed the cfg-visitor branch from d4e2623 to 4fa08e9 Compare January 28, 2025 07:49

Dylan-DPC 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 Feb 16, 2025

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rustbot assigned davidtwco and unassigned cjgillot Apr 8, 2025

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davidtwco 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 Apr 17, 2025

estebank added 3 commits August 1, 2025 21:50

Limit how deep we visit items to find cfg'd out names

5210c50

remove recursive search for items

4ba4559

estebank force-pushed the cfg-visitor branch from 4fa08e9 to 4ba4559 Compare August 1, 2025 22:03

estebank added 2 commits August 1, 2025 22:11

tiny cleanup

77f75f9

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 2, 2025

bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 2, 2025

bors merged commit 889701d into rust-lang:master Aug 2, 2025
11 checks passed

rustbot added this to the 1.90.0 milestone Aug 2, 2025

bors mentioned this pull request Aug 2, 2025

add AnonConstKind to non_trivial_const_arg diagnostics #144324

Draft

rustbot removed the perf-regression Performance regression. label Aug 2, 2025

Detect more cfgd out items in resolution errors #129183

Detect more cfgd out items in resolution errors #129183

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rust-timer commented Aug 20, 2024

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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Overall result: ❌✅ regressions and improvements - ACTION NEEDED

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Test differences

Job duration changes

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rust-timer commented Aug 2, 2025

Overall result: ❌ regressions - no action needed

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Detect more `cfg`d out items in resolution errors #129183

Detect more `cfg`d out items in resolution errors #129183