[rustc_resolve] Correctly keep all reexports in `ModChild::reexport_chain` by GuillaumeGomez · Pull Request #162543 · rust-lang/rust

GuillaumeGomez · 2026-09-09T15:28:53Z

First commit comes from #161872 and it's the base I used for the fix in the second commit (which also reverts basically everything from the first commit, not sure if I should keep it...). In short, NameResolution only seems to have access to local reexports and to the final reexported item. So instead, we keep the information in DeclKind (which cannot implement Drop because it's part of DeclData which is stored in ResolverArenas::dropless so I kept a slice instead of a SmallVec. Guess how I found out? Lots of panics :') ) and we use this information in reexport_chain.

r? @petrochenkov

GuillaumeGomez · 2026-09-09T15:34:52Z

@bors try @rust-timer queue

…, r=<try> [rustc_resolve] Correctly keep all reexports in `ModChild::reexport_chain`

rust-bors · 2026-09-09T16:35:08Z

☀️ Try build successful (CI)
Build commit: ad96898 (ad96898c9ea81f133409f573e53d98a7dc5eee46)
Base parent: 55c4dfe (55c4dfed758e741620e3320ed472ff5c4140856a)

rust-timer · 2026-09-09T23:22:03Z

Finished benchmarking commit (ad96898): 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 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)	0.4%	[0.2%, 0.6%]	11
Regressions ❌ (secondary)	0.3%	[0.2%, 0.3%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	1
All ❌✅ (primary)	0.4%	[0.2%, 0.6%]	11

Max RSS (memory usage)

Results (primary 0.7%, 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)	0.7%	[0.4%, 1.1%]	3
Regressions ❌ (secondary)	4.7%	[4.5%, 4.9%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-6.7%	[-9.0%, -4.4%]	3
All ❌✅ (primary)	0.7%	[0.4%, 1.1%]	3

Cycles

Results (primary 0.7%, secondary 0.9%)

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

	mean	range	count
Regressions ❌ (primary)	1.0%	[0.5%, 2.2%]	14
Regressions ❌ (secondary)	5.7%	[4.7%, 6.7%]	2
Improvements ✅ (primary)	-0.6%	[-0.7%, -0.5%]	3
Improvements ✅ (secondary)	-3.8%	[-4.8%, -2.8%]	2
All ❌✅ (primary)	0.7%	[-0.7%, 2.2%]	17

Binary size

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

Bootstrap: 480.775s -> 481.562s (0.16%)
Artifact size: 403.36 MiB -> 403.30 MiB (-0.01%)

GuillaumeGomez · 2026-09-10T15:20:45Z

@rustbot ready

GuillaumeGomez · 2026-09-15T21:37:03Z

All done and squashed commits. Thanks for starting it and for the reviews!

@bors r=petrochenkov

rust-bors · 2026-09-15T21:37:06Z

📌 Commit cb55fc7 has been approved by petrochenkov

It is now in the queue for this repository.

rust-bors · 2026-09-16T05:09:25Z

⌛ Testing commit cb55fc7 with merge 23ee25b...

Workflow: https://github.com/rust-lang/rust/actions/runs/35058393850

@petrochenkov

…, r=petrochenkov [rustc_resolve] Correctly keep all reexports in `ModChild::reexport_chain` Fixes #81893. First commit comes from #161872 and it's the base I used for the fix in the second commit (which also reverts basically everything from the first commit, not sure if I should keep it...). In short, `NameResolution` only seems to have access to local reexports and to the final reexported item. So instead, we keep the information in `DeclKind` (which cannot implement `Drop` because it's part of `DeclData` which is stored in `ResolverArenas::dropless` so I kept a slice instead of a `SmallVec`. Guess how I found out? Lots of `panic`s :') ) and we use this information in `reexport_chain`. r? @petrochenkov

Zalathar · 2026-09-16T05:14:04Z

@bors yield (to beta revert, which flaked out again)

rust-bors · 2026-09-16T05:14:08Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/35058393850

The next pull request likely to be tested is #162765.

rust-bors · 2026-09-16T05:27:10Z

⌛ Testing commit cb55fc7 with merge 14eb5ac...

Workflow: https://github.com/rust-lang/rust/actions/runs/35059565227

@petrochenkov

…, r=petrochenkov [rustc_resolve] Correctly keep all reexports in `ModChild::reexport_chain` Fixes #81893. First commit comes from #161872 and it's the base I used for the fix in the second commit (which also reverts basically everything from the first commit, not sure if I should keep it...). In short, `NameResolution` only seems to have access to local reexports and to the final reexported item. So instead, we keep the information in `DeclKind` (which cannot implement `Drop` because it's part of `DeclData` which is stored in `ResolverArenas::dropless` so I kept a slice instead of a `SmallVec`. Guess how I found out? Lots of `panic`s :') ) and we use this information in `reexport_chain`. r? @petrochenkov

Zalathar · 2026-09-16T09:30:25Z

Sadly the test-x86_64-msvc-1 job seems to have stalled.

@bors yield

rust-bors · 2026-09-16T09:30:29Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/35059565227

The next pull request likely to be tested is #162846.

Zalathar · 2026-09-16T09:31:12Z

Double-check that the job should have succeeded:

@bors try jobs=test-x86_64-msvc-1

…, r=<try> [rustc_resolve] Correctly keep all reexports in `ModChild::reexport_chain` try-job: test-x86_64-msvc-1

rust-bors · 2026-09-16T11:38:26Z

☀️ Try build successful (CI)
Build commit: 6dee990 (6dee99007bfef1d1efdf36005d271ad41e990f13)
Base parent: 28e8a8c (28e8a8c81bf3b37909edac6c2a76e56f30cd492f)

JonathanBrouwer · 2026-09-16T18:09:33Z

@bors rollup=iffy
Making a rollup of perf-sensitive PRs

…uwer Rollup of 4 perf-sensitive pull requests Successful merges: - #162450 (Cache block seeking results for initialized_at_terminator and _exit) - #162543 ([rustc_resolve] Correctly keep all reexports in `ModChild::reexport_chain`) - #162712 (perf: Keep the first macro syntax-context mapping inline) - #162747 (Lowering cleanups)

@petrochenkov

Rollup merge of #162543 - GuillaumeGomez:reexport-from-transient-crates, r=petrochenkov [rustc_resolve] Correctly keep all reexports in `ModChild::reexport_chain` Fixes #81893. First commit comes from #161872 and it's the base I used for the fix in the second commit (which also reverts basically everything from the first commit, not sure if I should keep it...). In short, `NameResolution` only seems to have access to local reexports and to the final reexported item. So instead, we keep the information in `DeclKind` (which cannot implement `Drop` because it's part of `DeclData` which is stored in `ResolverArenas::dropless` so I kept a slice instead of a `SmallVec`. Guess how I found out? Lots of `panic`s :') ) and we use this information in `reexport_chain`. r? @petrochenkov

rust-timer · 2026-09-17T08:51:12Z

Note

This PR was benchmarked as part of triage of its containing rollup: triage URL.

Finished benchmarking commit (a289e4f): comparison URL.

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

Our benchmarks found a performance regression caused by this PR.
This might be an actual regression, but it can also be just noise.

Next Steps:

If the regression was expected or you think it can be justified,
please write a comment with sufficient written justification, and add
@rustbot label: +perf-regression-triaged to it, to mark the regression as triaged.
If you think that you know of a way to resolve the regression, try to create
a new PR with a fix for the regression.
If you do not understand the regression or you think that it is just noise,
you can ask the @rust-lang/wg-compiler-performance working group for help (members of this group
were already notified of this PR).

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.4%	[0.2%, 0.8%]	11
Regressions ❌ (secondary)	0.4%	[0.3%, 0.7%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.8%	[-0.8%, -0.8%]	3
All ❌✅ (primary)	0.4%	[0.2%, 0.8%]	11

Max RSS (memory usage)

Results (primary -0.2%, 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)	2.0%	[2.0%, 2.0%]	1
Regressions ❌ (secondary)	3.4%	[1.0%, 5.2%]	3
Improvements ✅ (primary)	-2.4%	[-2.4%, -2.4%]	1
Improvements ✅ (secondary)	-4.7%	[-5.5%, -4.1%]	5
All ❌✅ (primary)	-0.2%	[-2.4%, 2.0%]	2

Cycles

Results (primary 2.1%)

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

Binary size

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

Bootstrap: missing data
Artifact size: 406.75 MiB -> 408.73 MiB (0.49%)

rustbot assigned petrochenkov Sep 9, 2026

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rust-bors Bot pushed a commit that referenced this pull request Sep 9, 2026

Auto merge of #162543 - GuillaumeGomez:reexport-from-transient-crates…

ad96898

…, r=<try> [rustc_resolve] Correctly keep all reexports in `ModChild::reexport_chain`

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petrochenkov 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 Sep 9, 2026

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petrochenkov reviewed Sep 10, 2026

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Comment thread compiler/rustc_resolve/src/build_reduced_graph.rs Outdated

petrochenkov 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 Sep 10, 2026

GuillaumeGomez force-pushed the reexport-from-transient-crates branch from 5996a38 to 200b561 Compare September 10, 2026 13:47

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GuillaumeGomez added 2 commits September 15, 2026 23:31

resolve: Concatenate reexport chains from all crates

73b1560

Add regression test for reexport chain in transient crates

cb55fc7

GuillaumeGomez force-pushed the reexport-from-transient-crates branch from 5d8fceb to cb55fc7 Compare September 15, 2026 21:31

rust-bors Bot 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 Sep 15, 2026

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rust-bors Bot pushed a commit that referenced this pull request Sep 16, 2026

Auto merge of #162543 - GuillaumeGomez:reexport-from-transient-crates…

6dee990

…, r=<try> [rustc_resolve] Correctly keep all reexports in `ModChild::reexport_chain` try-job: test-x86_64-msvc-1

JonathanBrouwer mentioned this pull request Sep 16, 2026

Rollup of 4 perf-sensitive pull requests #162859

Merged

rust-bors Bot merged commit ef0d430 into rust-lang:main Sep 17, 2026
14 of 15 checks passed

rustbot added this to the 1.100.0 milestone Sep 17, 2026

GuillaumeGomez deleted the reexport-from-transient-crates branch September 17, 2026 08:57

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

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

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