Resolver: Batched Import Resolution by LorrensP-2158466 · Pull Request #145108 · rust-lang/rust

LorrensP-2158466 · 2025-08-08T15:54:37Z

Transforms the current algorithm for resolving imports to a batched algorithm. Every import in the indeterminate_imports set is resolved in isolation. This is the only real difference from the current algorithm.

r? petrochenkov

compiler/rustc_resolve/src/lib.rs

compiler/rustc_resolve/src/imports.rs

LorrensP-2158466 · 2025-08-11T19:29:42Z

Code looks a little better now and should be more correct than the previous commits, but I have yet to find a way to resolve the current test failures.

LorrensP-2158466 · 2025-08-11T20:34:04Z

Okey, I did fix core not being built, but those other errors happened again. We now resolve the prelude import path when we create such an import at build_reduced_graph phase.

petrochenkov · 2025-08-11T22:39:59Z

Could you update the tests to make CI green, so I can see the difference?
(Even if the changes do not seem correct.)

tests/ui/imports/ambiguous-9.rs

tests/ui/imports/glob-conflict-cross-crate-1.rs

tests/ui/proc-macro/derive-helper-legacy-spurious.rs

petrochenkov · 2025-08-12T17:43:51Z

Moving prelude_import processing to build_reduced_graph may also be necessary for #139493.

LorrensP-2158466 · 2025-08-12T17:49:54Z

I'll create a pr for it.

compiler/rustc_resolve/src/imports.rs

craterbot · 2026-02-23T00:45:10Z

🎉 Experiment pr-145108-2 is completed!
📊 161 regressed and 1 fixed (821749 total)
📊 2472 spurious results on the retry-regressed-list.txt, consider a retry¹ if this is a significant amount.
📰 Open the summary report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

re-run the experiment with crates=https://crater-reports.s3.amazonaws.com/pr-145108-2/retry-regressed-list.txt ↩

petrochenkov · 2026-02-23T06:33:06Z

Looks like rust-embed is still a problem.
Could you rebase, squash commits and re-apply the rust-embed hack commit on top of the other changes?
@rustbot author

LorrensP-2158466 · 2026-02-24T17:04:31Z

Fixed conflicts, squashed and re-applied rust-embed fix. @rustbot ready

compiler/rustc_resolve/src/imports.rs

Import resolution now happens in 2 phases: 1. We resolve all undetermined and collect their resolutions 2. Write all resolutions to the Resolver state. Repeat this untill we reach a fix point. + Bless tests

rustbot · 2026-03-08T15:30:59Z

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.

LorrensP-2158466 · 2026-03-08T15:32:53Z

Rebased to fix the conflicts.

The rustembed hack is a bit more generic, than just checking for RustEmbed.

@rustbot ready

compiler/rustc_resolve/src/imports.rs

petrochenkov · 2026-03-08T18:23:08Z

The rustembed hack is a bit more generic, than just checking for RustEmbed.

Here we need to address a specific set of regressions caused by one specific crate, not bend the language rules in general, the smaller the scope of the hack is the better.
The ambiguous_import_visibilities lint is the more generic solution.

LorrensP-2158466 · 2026-03-09T11:47:18Z

Yes, that's right, I forgot to make myself clear why I made it generic. I couldn't exactly find a way to these 2 points:

X is from macro_use_prelude and has name RustEmbed
module has a macro namespace binding Y with name RustEmbed in it

I couldn't exactly find a way to check exactly with the name RustEmbed. So I wanted to ask how I can search for a binding with identifier RustEmbed or check that X has such an identifier. Sorry

compiler/rustc_resolve/src/imports.rs

LorrensP-2158466 · 2026-03-11T11:23:46Z

Didn't know I could just add a new symbol, thanks!

@rustbot ready

petrochenkov · 2026-03-11T11:34:46Z

@bors try

petrochenkov · 2026-03-11T11:37:02Z

TODO: @craterbot check p=1 crates=https://crater-reports.s3.amazonaws.com/pr-145108-2/retry-regressed-list.txt

rust-bors · 2026-03-11T13:42:45Z

☀️ Try build successful (CI)
Build commit: 0799524 (0799524677c1163b7afa649c7b4006f3d351a1c1, parent: b2fabe39bde5174e8d728bb85f2b8d0572c35b74)

petrochenkov · 2026-03-11T13:47:48Z

@craterbot check p=1 crates=https://crater-reports.s3.amazonaws.com/pr-145108-2/retry-regressed-list.txt

craterbot · 2026-03-11T13:47:54Z

👌 Experiment pr-145108-3 created and queued.
🤖 Automatically detected try build 0799524
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

craterbot · 2026-03-13T13:10:06Z

🚧 Experiment pr-145108-3 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

craterbot · 2026-03-13T16:52:26Z

🎉 Experiment pr-145108-3 is completed!
📊 31 regressed and 0 fixed (2551 total)
📊 179 spurious results on the retry-regressed-list.txt, consider a retry¹ if this is a significant amount.
📰 Open the summary report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

re-run the experiment with crates=https://crater-reports.s3.amazonaws.com/pr-145108-3/retry-regressed-list.txt ↩

petrochenkov · 2026-03-13T17:23:31Z

Need regression analysis, each of the regressions need to fall under one of the deprecation lints we've merged recently.
I'll do it myself in a few days.

petrochenkov · 2026-03-16T15:01:08Z

Analysis:

ambiguous_glob_imported_traits - 22 regressions

neivv.animosity.895eaccfc1ba49a5815799e25041926df23bd46b
iceoryx2-0.8.1
youngday.easy_example.a90b81e8df86e42bea2b46995041f9fbfba8dae0 (iceoryx2-0.8.0)
cu-iceoryx2-sink-0.12.0 (iceoryx2-0.8.0)
cu-iceoryx2-src-0.12.0 (iceoryx2-0.8.0)
2mauis.iox2_gsml_time_sync.e92fb4e8fbf57da0e14fcb734fb1249eba450b5a (iceoryx2-0.8.1)
cu-iceoryx2-bridge-0.13.0 (iceoryx2-0.8.1)
iceoryx2-conformance-tests-0.8.1 (iceoryx2-0.8.1)
iceoryx2-services-discovery-0.8.1 (iceoryx2-0.8.1)
iceoryx2-tunnel-backend-0.8.1 (iceoryx2-0.8.1)
iceoryx2-tunnel-conformance-tests-0.8.1 (iceoryx2-0.8.1)
iceoryx2-tunnel-zenoh-0.8.1 (iceoryx2-0.8.1)
iceoryx2-tunnel-0.8.1 (iceoryx2-0.8.1)
iceoryx2-userland-record-and-replay-0.8.1 (iceoryx2-0.8.1)
asenetcky.api-testing.9d3c89857a5aaf205ef15237a321e4f861180bed (polars-plan-0.49.1)
charles-turner-1.pqdump.d8d0356c5b10f18cab13975543c5a9a57bcf8ac8 (polars-plan-0.51.0)
italoag.rfb-rs.95b747eaa7b0d5ad1347366cc77addf3b92ea5f3 (polars-plan-0.51.0)
anndata-hdf5-0.5.2 (polars-plan-0.51.0)
anndata-memory-1.0.7 (polars-plan-0.51.0)
anndata-0.6.2 (polars-plan-0.51.0)
parqeye-0.0.2 (polars-plan-0.51.0)
pyanndata-0.6.0 (polars-plan-0.51.0)

ambiguous_import_visibilities - 4 regressions

contextgeneric.hypershell.4a5e50ccfcd954cb1182c834d1fafab0b54d1a63
informalsystems.cgp.3f33054faa225acdb8aa0744e9b40f7c8027b78e
cgp-tests-0.7.0
hypershell-0.1.0

unused_imports + deny(warnings) - 5 (not really) regressions

binggan-0.15.3
coasys_juniper_subscriptions-0.17.0
juniper_subscriptions_puff-0.17.0-dev
measurements-0.11.1
mockall_derive-0.14.0

petrochenkov · 2026-03-16T15:04:11Z

@LorrensP-2158466
Could you fix the issue in iceoryx2-0.8.1 and ask them to make a patch release?
In the latest version of polars-plan the issue is already fixed.

petrochenkov · 2026-03-16T15:13:39Z

This is not exactly a language change, but I'm going to nominate this for lang team because of the breakage.

Change description for lang team

This change effectively turns some instances of import ambiguity deprecation lints ambiguous_glob_imported_traits and ambiguous_import_visibilities into hard errors (see the list from crater - #145108 (comment)).

The goal of these lints is to catch cases in which results of name resolution are unpredictable and depend on internal details of the name resolution implementation.
This PR actually changes those internal details in preparation for import resolution parallelization, which makes some ambiguous code change its interpretation and report errors.
If those lints completed their life cycle and turned into hard errors, this PR wouldn't cause any breakage.

LorrensP-2158466 · 2026-03-16T15:42:24Z

Could you fix the issue in iceoryx2-0.8.1 and ask them to make a patch release?

I just checked and it seems that it's fixed but not yet released? I verified it by running this version of the compiler on both the latest changes and on iceoryx@0.8.1 using cargo clone.

rustbot assigned petrochenkov Aug 8, 2025

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LorrensP-2158466 marked this pull request as ready for review August 11, 2025 08:37

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LorrensP-2158466 force-pushed the batched-import-resolution branch from a3f8ae2 to 4a2a0dc Compare August 11, 2025 20:37

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LorrensP-2158466 added 2 commits March 8, 2026 16:27

Resolver: Batched import resolution.

a54d3a4

Import resolution now happens in 2 phases: 1. We resolve all undetermined and collect their resolutions 2. Write all resolutions to the Resolver state. Repeat this untill we reach a fix point. + Bless tests

hack for RustEmbed with updated test

fb2ab4b

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make rustembed hack only work for rustembed

5cd22e1

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