rustfmt: Discover modules via `cfg_select!` by mkroening · Pull Request #158372 · rust-lang/rust

mkroening · 2026-06-24T17:40:31Z

This PR renames all occurrences of cfg_match! in rustfmt to cfg_select!. This makes the module file detection logic from rust-lang/rustfmt#6522 kick in for cfg_select! instead of cfg_match!, which no longer exists.

This PR performs no other adjustments to the logic to be as small as possible.

I am opening this PR in this repo since that is also the target for the more comprehensive #154202, which covers more than merely detecting other files through cfg_select!.

Closes #158371.

CC: @ytmimi, @CAD97

rustbot · 2026-06-24T17:40:34Z

rustfmt is developed in its own repository. If possible, consider making this change to rust-lang/rustfmt instead.

cc @rust-lang/rustfmt

rustbot · 2026-06-24T17:40:37Z

r? @ytmimi

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tgross35 · 2026-06-24T22:29:25Z

@rustbot label +beta-nominated

cfg_select has already been stable for a few releases so there's a bit of a gap here. Since the only change is a renaming, it seems potentially feasible to backport.

ytmimi · 2026-06-25T16:07:07Z

Overall I think this is a good change, and although it would technically be breaking since we'd end up formatting modules listed inside the cfg_select! there is some president with let-else, which was mentioned in an earlier comment. I think as long as we mention this change in the release notes we should be fine, and I'm sure users would welcome this fix. I'm at work right now, but will review this today when I have some free time.

ytmimi

I think there are still a few references to the old cfg_match! that we should change. Once that's done and we figure out how we'll disclose this breaking change you can r=me.

I think it's fine to get this out before cfg_select! formatting lands since I agree that the impact of entire modules being left unformatted is larger than what will change once we start formatting cfg_select! calls.

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cuviper · 2026-06-29T17:16:06Z

(As T-release) Please note that it's getting late for 1.97-beta backports -- ideally this should be merged and labeled beta-accepted before Friday, but at that point we won't have much meaningful beta testing time left either. Maybe it would be better to just let it ride the normal release train?

jieyouxu · 2026-06-30T01:13:56Z

At that point, probably yeah.

mkroening · 2026-06-30T08:32:44Z

I think the changes themselves should be fine now.

Once we figure out how we'll disclose this breaking change you can r=me.

Is there any way I can help with that? Should I write something for the release notes or do something else?

tgross35 · 2026-07-20T17:40:19Z

@jieyouxu would you be willing to merge this one since Yacin approved?

Once we figure out how we'll disclose this breaking change you can r=me.

Is there any way I can help with that? Should I write something for the release notes or do something else?

I added the relnotes label, you can add something to #159615.

jieyouxu

Thanks, since the cfg_match -> cfg_select renames are now also done, and we have an associated relnotes issue...
@bors r=ytmimi,jieyouxu

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rust-bors · 2026-07-24T04:11:58Z

📌 Commit facc787 has been approved by ytmimi,jieyouxu

It is now in the queue for this repository.

Rollup of 14 pull requests Successful merges: - #159765 (Avoid spurious rebuilds of JSON docs in bootstrap) - #159781 (Update bootstrap to use -Zembed-metadata=no instead of -Zno-embed-metadata) - #158362 (trait solver: account for universes from replace_bound_vars) - #158372 (rustfmt: Discover modules via `cfg_select!`) - #159173 (Add allowed list check on EII implementations attributes) - #159718 (Make `DocLinkResMap` an `FxIndexMap`) - #159722 ( [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature) - #159731 (std: Implement futex on wasip3 targets, update target spec) - #159755 (Improve consistency of attribute error messages) - #155795 (constify `vec![1, 2, 3]` macro) - #157776 (ci: Enable autodiff tests on x86_64 linux) - #158766 (Promote riscv64-unknown-linux-musl to tier 2 with host tools) - #159271 (str: add ASCII fast path to word_to_titlecase) - #159667 (Make some parser structured suggestions verbose and tweak their wording)

@ytmimi

Rollup merge of #158372 - mkroening:rustfmt-cfg_select-modules, r=ytmimi,jieyouxu rustfmt: Discover modules via `cfg_select!` This PR renames all occurrences of `cfg_match!` in rustfmt to `cfg_select!`. This makes the module file detection logic from rust-lang/rustfmt#6522 kick in for `cfg_select!` instead of `cfg_match!`, which no longer exists. This PR performs no other adjustments to the logic to be as small as possible. I am opening this PR in this repo since that is also the target for the more comprehensive #154202, which covers more than merely detecting other files through `cfg_select!`. Closes #158371. CC: @ytmimi, @CAD97

Rollup of 14 pull requests Successful merges: - rust-lang/rust#159765 (Avoid spurious rebuilds of JSON docs in bootstrap) - rust-lang/rust#159781 (Update bootstrap to use -Zembed-metadata=no instead of -Zno-embed-metadata) - rust-lang/rust#158362 (trait solver: account for universes from replace_bound_vars) - rust-lang/rust#158372 (rustfmt: Discover modules via `cfg_select!`) - rust-lang/rust#159173 (Add allowed list check on EII implementations attributes) - rust-lang/rust#159718 (Make `DocLinkResMap` an `FxIndexMap`) - rust-lang/rust#159722 ( [rustdoc] Retrieve `cfg_attr` information for derived impls for `doc_cfg` feature) - rust-lang/rust#159731 (std: Implement futex on wasip3 targets, update target spec) - rust-lang/rust#159755 (Improve consistency of attribute error messages) - rust-lang/rust#155795 (constify `vec![1, 2, 3]` macro) - rust-lang/rust#157776 (ci: Enable autodiff tests on x86_64 linux) - rust-lang/rust#158766 (Promote riscv64-unknown-linux-musl to tier 2 with host tools) - rust-lang/rust#159271 (str: add ASCII fast path to word_to_titlecase) - rust-lang/rust#159667 (Make some parser structured suggestions verbose and tweak their wording)

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-rustfmt Relevant to the rustfmt team, which will review and decide on the PR/issue. labels Jun 24, 2026

rustbot assigned ytmimi Jun 24, 2026

CAD97 approved these changes Jun 24, 2026

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rustbot added the beta-nominated Nominated for backporting to the compiler in the beta channel. label Jun 24, 2026

jieyouxu reviewed Jun 25, 2026

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Comment thread src/tools/rustfmt/tests/target/cfg_select/lib.rs

mkroening mentioned this pull request Jun 25, 2026

rustfmt does not discover modules through cfg_select! #158371

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ytmimi approved these changes Jun 25, 2026

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Comment thread src/tools/rustfmt/src/modules/visitor.rs Outdated

Comment thread src/tools/rustfmt/src/modules/visitor.rs Outdated

mkroening force-pushed the rustfmt-cfg_select-modules branch from 3ba2282 to a71b047 Compare June 26, 2026 09:43

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mkroening force-pushed the rustfmt-cfg_select-modules branch from a71b047 to 4e98db3 Compare June 26, 2026 13:45

rustfmt: Discover modules via cfg_select!

facc787

mkroening force-pushed the rustfmt-cfg_select-modules branch from 4e98db3 to facc787 Compare June 26, 2026 13:48

tgross35 added the relnotes Marks issues that should be documented in the release notes of the next release. label Jul 20, 2026

rustbot mentioned this pull request Jul 20, 2026

Tracking issue for release notes of #158372: rustfmt: Discover modules via cfg_select! #159615

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jieyouxu approved these changes Jul 24, 2026

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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-review Status: Awaiting review from the assignee but also interested parties. labels Jul 24, 2026

jhpratt mentioned this pull request Jul 24, 2026

Rollup of 14 pull requests #159814

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rust-bors Bot merged commit 7a183d7 into rust-lang:main Jul 24, 2026
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rustbot added this to the 1.99.0 milestone Jul 24, 2026

mkroening deleted the rustfmt-cfg_select-modules branch July 24, 2026 11:58

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