enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group by hkBst · Pull Request #159179 · rust-lang/rust

hkBst · 2026-07-12T13:28:27Z

This enables the unreachable_cfg_select_predicates lint as part of the unused lint group. This was apparently planned to be enabled as part of cfg_select stabilization, but got overlooked (as can be seen from comments below).

This lint was merged in #149960 which also includes a test for the behavior in tests/ui/macros/cfg_select.rs.

rustbot · 2026-07-12T13:28:32Z

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mejrs · 2026-07-12T17:01:44Z

I'm confused, isn't this just adding it to the "unused" lint group? It's been stable since #149783

@folkertdev was this simply forgotten when cfg_select! was stabilized?

folkertdev · 2026-07-12T17:04:23Z

Oh, looks like it yeah. Technically T-lang might have to approve this then?

mejrs · 2026-07-12T18:24:20Z

It looks that way. Is this still something we want?

If so @hkBst can you make a small writeup explaining this change and edit the pr title accordingly, and then nominate it for T-lang?

folkertdev · 2026-07-12T18:30:06Z

I think that we do want this yes. The lint was introduced in #149960, that PR itself deliberately did not go through FCP because the lint was not observable without having the cfg_select feature enabled.

davidtwco

r=me, impl looks good once lang approves

View changes since this review

Since cfg_select is stable since 1.95, this can be enabled.

hkBst · 2026-07-13T12:44:11Z

Thanks to @folkertdev for providing the context (and actually implementing this lint), I was able to improve the PR text and title. So I think this should be good now, @mejrs.

I don't know why this results in one additional copy of an unrelated error being reported in some tests. But since it's already duplicated many times, I guess it is fine.

@rustbot ready

traviscross · 2026-07-14T22:00:20Z

Makes sense. Thanks @hkBst and @folkertdev (and @davidtwco for the review).

@rfcbot fcp merge lang

rust-rfcbot · 2026-07-14T22:00:22Z

@traviscross has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

cc @rust-lang/lang-advisors: FCP proposed for lang, please feel free to register concerns.
See this document for info about what commands tagged team members can give me.

nikomatsakis · 2026-07-15T15:09:01Z

@rfcbot reviewed

rust-rfcbot · 2026-07-25T15:09:47Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

folkertdev · 2026-07-25T15:27:19Z

@bors r=davidtwco

rust-bors · 2026-07-25T15:27:22Z

📌 Commit e91e00f has been approved by davidtwco

It is now in the queue for this repository.

enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group This enables the `unreachable_cfg_select_predicates` lint as part of the `unused` lint group. This was apparently planned to be enabled as part of `cfg_select` stabilization, but got overlooked (as can be seen from comments below). This lint was merged in rust-lang#149960 which also includes a test for the behavior in `tests/ui/macros/cfg_select.rs`.

…uwer Rollup of 25 pull requests Successful merges: - #138618 (Support using const pointers in asm `const` operand) - #157962 (Lower paths to functions in const args as ConstKind::Error) - #158404 (trait_solver: normalize next-gen region constraints) - #158709 (rustdoc: warn on improperly interleaved HTML/MD) - #159174 (Fix implicit_provenance_casts warnings on Xous) - #159179 (enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group) - #159518 (iter: extend step_by specialization to cover StepBy<RangeIter<{integer}>>) - #159673 (bootstrap: forward -fdebug-prefix-map when using cc) - #159700 (Split non-local `semicolon_in_expressions_from_macros` into a separate lint) - #159720 (document #[global_allocator] constraints) - #159732 (optimization: don't look for diagnostic/canonical items without rustc_attrs enabled) - #159738 (implement `CovariantUnsafeCell`) - #159740 (reuse regular exported_non_generic_symbols logic in Miri) - #159780 (check `extern "custom"` function pointers) - #159785 (Share _Unwind_Exception definition between native and wasm) - #159786 (rustdoc-js: ignore editor temp files in test folder discovery) - #159819 (std::sync::poison: disable auto_cfg on PoisonError::new) - #155388 (stepping into where-clauses during normalization may be productive) - #155914 (when bailing on ambiguity, don't force other results to ambig) - #159204 (Add support to caller_location to rustc_public) - #159439 (Fix(lib/fs/win): Fall back on Win32 delete for `Dir::remove_file`) - #159676 (Update wasm-component-ld to 0.5.27) - #159695 (proc_macro: Fix cfg_attr inner attrs in file modules) - #159730 (allow accessing the contents of UnsafeCell without going through get) - #159809 (Avoid `#[target_features]`)

enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group This enables the `unreachable_cfg_select_predicates` lint as part of the `unused` lint group. This was apparently planned to be enabled as part of `cfg_select` stabilization, but got overlooked (as can be seen from comments below). This lint was merged in rust-lang#149960 which also includes a test for the behavior in `tests/ui/macros/cfg_select.rs`.

…uwer Rollup of 25 pull requests Successful merges: - #159825 (codegen: handle OperandValue::Uninit in codegen_return_terminator) - #138618 (Support using const pointers in asm `const` operand) - #157962 (Lower paths to functions in const args as ConstKind::Error) - #158404 (trait_solver: normalize next-gen region constraints) - #158709 (rustdoc: warn on improperly interleaved HTML/MD) - #159174 (Fix implicit_provenance_casts warnings on Xous) - #159179 (enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group) - #159518 (iter: extend step_by specialization to cover StepBy<RangeIter<{integer}>>) - #159673 (bootstrap: forward -fdebug-prefix-map when using cc) - #159700 (Split non-local `semicolon_in_expressions_from_macros` into a separate lint) - #159720 (document #[global_allocator] constraints) - #159732 (optimization: don't look for diagnostic/canonical items without rustc_attrs enabled) - #159738 (implement `CovariantUnsafeCell`) - #159740 (reuse regular exported_non_generic_symbols logic in Miri) - #159780 (check `extern "custom"` function pointers) - #159786 (rustdoc-js: ignore editor temp files in test folder discovery) - #159819 (std::sync::poison: disable auto_cfg on PoisonError::new) - #155388 (stepping into where-clauses during normalization may be productive) - #155914 (when bailing on ambiguity, don't force other results to ambig) - #159204 (Add support to caller_location to rustc_public) - #159439 (Fix(lib/fs/win): Fall back on Win32 delete for `Dir::remove_file`) - #159676 (Update wasm-component-ld to 0.5.27) - #159695 (proc_macro: Fix cfg_attr inner attrs in file modules) - #159730 (allow accessing the contents of UnsafeCell without going through get) - #159809 (Avoid `#[target_features]`)

enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group This enables the `unreachable_cfg_select_predicates` lint as part of the `unused` lint group. This was apparently planned to be enabled as part of `cfg_select` stabilization, but got overlooked (as can be seen from comments below). This lint was merged in rust-lang#149960 which also includes a test for the behavior in `tests/ui/macros/cfg_select.rs`.

Rollup of 25 pull requests Successful merges: - #138618 (Support using const pointers in asm `const` operand) - #157962 (Lower paths to functions in const args as ConstKind::Error) - #158709 (rustdoc: warn on improperly interleaved HTML/MD) - #159174 (Fix implicit_provenance_casts warnings on Xous) - #159179 (enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group) - #159518 (iter: extend step_by specialization to cover StepBy<RangeIter<{integer}>>) - #159673 (bootstrap: forward -fdebug-prefix-map when using cc) - #159700 (Split non-local `semicolon_in_expressions_from_macros` into a separate lint) - #159720 (document #[global_allocator] constraints) - #159732 (optimization: don't look for diagnostic/canonical items without rustc_attrs enabled) - #159738 (implement `CovariantUnsafeCell`) - #159740 (reuse regular exported_non_generic_symbols logic in Miri) - #159780 (check `extern "custom"` function pointers) - #159786 (rustdoc-js: ignore editor temp files in test folder discovery) - #159819 (std::sync::poison: disable auto_cfg on PoisonError::new) - #152439 (Fix typos and grammar in library documentation) - #155388 (stepping into where-clauses during normalization may be productive) - #155914 (when bailing on ambiguity, don't force other results to ambig) - #159204 (Add support to caller_location to rustc_public) - #159439 (Fix(lib/fs/win): Fall back on Win32 delete for `Dir::remove_file`) - #159676 (Update wasm-component-ld to 0.5.27) - #159695 (proc_macro: Fix cfg_attr inner attrs in file modules) - #159730 (allow accessing the contents of UnsafeCell without going through get) - #159809 (Avoid `#[target_features]`) - #159878 (bootstrap: Remove obsolete option `build.compiletest-use-stage0-libtest`)

Rollup merge of #159179 - hkBst:patch-7, r=davidtwco enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group This enables the `unreachable_cfg_select_predicates` lint as part of the `unused` lint group. This was apparently planned to be enabled as part of `cfg_select` stabilization, but got overlooked (as can be seen from comments below). This lint was merged in #149960 which also includes a test for the behavior in `tests/ui/macros/cfg_select.rs`.

rustbot assigned davidtwco Jul 12, 2026

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 Jul 12, 2026

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folkertdev added the F-cfg_select `#![feature(cfg_select)]` label Jul 12, 2026

mejrs 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 Jul 12, 2026

folkertdev added I-lang-nominated Nominated for discussion during a lang team meeting. I-lang-easy-decision Issue: The decision needed by the team is conjectured to be easy; this does not imply nomination labels Jul 12, 2026

davidtwco approved these changes Jul 13, 2026

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enable UNREACHABLE_CFG_SELECT_PREDICATES lint

e91e00f

Since cfg_select is stable since 1.95, this can be enabled.

rust-cloud-vms Bot force-pushed the patch-7 branch from 167acea to e91e00f Compare July 13, 2026 12:15

hkBst changed the title ~~enable UNREACHABLE_CFG_SELECT_PREDICATES lint~~ enable unreachable_cfg_select_predicates lint as part of unused lint group Jul 13, 2026

rustbot 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 Jul 13, 2026

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traviscross added I-lang-radar Items that are on lang's radar and will need eventual work or consideration. and removed P-lang-drag-1 Lang team prioritization drag level 1. https://rust-lang.zulipchat.com/#narrow/channel/410516-t-lang labels Jul 15, 2026

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rustbot mentioned this pull request Jul 25, 2026

Tracking issue for release notes of #159179: enable unreachable_cfg_select_predicates lint as part of unused lint group #159909

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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 25, 2026

JonathanBrouwer mentioned this pull request Jul 25, 2026

Rollup of 25 pull requests #159920

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JonathanBrouwer mentioned this pull request Jul 25, 2026

Rollup of 25 pull requests #159926

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This was referenced Jul 26, 2026

Rollup of 25 pull requests #159941

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Rollup of 25 pull requests #159942

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rust-bors Bot merged commit b197050 into rust-lang:main Jul 26, 2026
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rustbot added this to the 1.99.0 milestone Jul 26, 2026

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