Remove `cfg_match` from the prelude by c410-f3r · Pull Request #117162 · rust-lang/rust

c410-f3r · 2023-10-25T12:44:32Z

rustbot · 2023-10-25T12:44:40Z

(rustbot has picked a reviewer for you, use r? to override)

cuviper · 2023-10-25T16:10:44Z

We also approved beta backport in the libs meeting:
https://rust-lang.zulipchat.com/#narrow/stream/259402-t-libs.2Fmeetings/topic/Meeting.202023-10-25/near/398512237

@rustbot label +beta-accepted

workingjubilee · 2023-10-28T08:42:09Z

Thanks!
@bors r+

bors · 2023-10-28T08:42:11Z

📌 Commit 0b96e47 has been approved by workingjubilee

It is now in the queue for this repository.

Remove `cfg_match` from the prelude Fixes rust-lang#117057 cc rust-lang#115585

…kingjubilee Rollup of 8 pull requests Successful merges: - rust-lang#115773 (tvOS simulator support on Apple Silicon for rustc) - rust-lang#117162 (Remove `cfg_match` from the prelude) - rust-lang#117170 (Add support for i586-unknown-netbsd as target.) - rust-lang#117259 (Declare rustc_target's dependency on object/macho) - rust-lang#117311 (-Zunpretty help: add missing possible values) - rust-lang#117316 (Mark constructor of `BinaryHeap` as const fn) - rust-lang#117319 (explain why we don't inline when target features differ) - rust-lang#117325 (Small ty::print cleanups) r? `@ghost` `@rustbot` modify labels: rollup

…kingjubilee Rollup of 5 pull requests Successful merges: - rust-lang#115773 (tvOS simulator support on Apple Silicon for rustc) - rust-lang#117162 (Remove `cfg_match` from the prelude) - rust-lang#117311 (-Zunpretty help: add missing possible values) - rust-lang#117316 (Mark constructor of `BinaryHeap` as const fn) - rust-lang#117319 (explain why we don't inline when target features differ) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#117162 - c410-f3r:try, r=workingjubilee Remove `cfg_match` from the prelude Fixes rust-lang#117057 cc rust-lang#115585

[beta] backports - ensure the parent path's existence on `x install` rust-lang#116349 - Remove `cfg_match` from the prelude rust-lang#117162 - improve and fix `x install` rust-lang#117383 - Update to LLVM 17.0.4 rust-lang#117436 r? cuviper

Skgland · 2023-12-18T21:47:36Z

Would this be something to add to the 2024 edition prelude,even while it is still unstable?
So that, once it is stable, it can be at least in that editions prelude without breakage.

@traviscross

…=JonathanBrouwer stabilize `cfg_select!` *[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/149783)* tracking issue: rust-lang#115585 closes rust-lang#115585 reference PR: - rust-lang/reference#2103 # Request for Stabilization ## Summary The `cfg_select!` macro picks the expansion corresponding to the first `cfg` condition that evaluates to `true`. It simplifies complex conditional expressions. ```rust cfg_select! { unix => { fn foo() { /* unix specific functionality */ } } target_pointer_width = "32" => { fn foo() { /* non-unix, 32-bit functionality */ } } _ => { fn foo() { /* fallback implementation */ } } } let is_unix_str = cfg_select! { unix => "unix", _ => "not unix", }; println!("{is_unix_str}"); ``` ## Semantics The expansion of a `cfg_select!` call is the right-hand side of the first `cfg` rule that evaluates to true. This can be roughly expressed using this macro: ```rust macro_rules! cfg_select { ({ $($tt:tt)* }) => {{ $crate::cfg_select! { $($tt)* } }}; (_ => { $($output:tt)* }) => { $($output)* }; ( $cfg:meta => $output:tt $($( $rest:tt )+)? ) => { #[cfg($cfg)] $crate::cfg_select! { _ => $output } $( #[cfg(not($cfg))] $crate::cfg_select! { $($rest)+ } )? } } ``` The actual implementation uses a builtin macro so that `cfg_select!` can be used both in item and expression position. ## Documentation reference PR: - rust-lang/reference#2103 ## Tests The `cfg_select!` macro is already used extensively in the rust compiler codebase. It has several dedicated tests: - [`tests/ui/check-cfg/cfg-select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/check-cfg/cfg-select.rs)tests that warnings are emitted when an unexpected `cfg` condition is used. - [`tests/ui/macros/cfg_select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/macros/cfg_select.rs) tests that `cfg_select!` has the expected expansion, and tests that the expected syntax is accepted. ## History - rust-lang#115416 - rust-lang#117162 - rust-lang#133720 - rust-lang#135625 - rust-lang#137198 - rust-lang#138993 - rust-lang#138996 - rust-lang#143461 - rust-lang#143941 - rust-lang#145233 - rust-lang#148712 - rust-lang#149380 - rust-lang#149925 # Resolved questions # Unresolved questions The style team has decided on how to format `cfg_select!`, but this formatting has not yet been implemented. See rust-lang#144323. r? @traviscross   > [!NOTE] > # Concerns (0 active) > > - ~~[allowing-comma-after-closing-brace](rust-lang#149783 (comment) resolved in [this comment](rust-lang#149783 (comment)) > > *Managed by `@rustbot`—see [help](https://forge.rust-lang.org/triagebot/concern.html) for details.*

@traviscross

…=JonathanBrouwer stabilize `cfg_select!` *[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/149783)* tracking issue: rust-lang#115585 closes rust-lang#115585 reference PR: - rust-lang/reference#2103 # Request for Stabilization ## Summary The `cfg_select!` macro picks the expansion corresponding to the first `cfg` condition that evaluates to `true`. It simplifies complex conditional expressions. ```rust cfg_select! { unix => { fn foo() { /* unix specific functionality */ } } target_pointer_width = "32" => { fn foo() { /* non-unix, 32-bit functionality */ } } _ => { fn foo() { /* fallback implementation */ } } } let is_unix_str = cfg_select! { unix => "unix", _ => "not unix", }; println!("{is_unix_str}"); ``` ## Semantics The expansion of a `cfg_select!` call is the right-hand side of the first `cfg` rule that evaluates to true. This can be roughly expressed using this macro: ```rust macro_rules! cfg_select { ({ $($tt:tt)* }) => {{ $crate::cfg_select! { $($tt)* } }}; (_ => { $($output:tt)* }) => { $($output)* }; ( $cfg:meta => $output:tt $($( $rest:tt )+)? ) => { #[cfg($cfg)] $crate::cfg_select! { _ => $output } $( #[cfg(not($cfg))] $crate::cfg_select! { $($rest)+ } )? } } ``` The actual implementation uses a builtin macro so that `cfg_select!` can be used both in item and expression position. ## Documentation reference PR: - rust-lang/reference#2103 ## Tests The `cfg_select!` macro is already used extensively in the rust compiler codebase. It has several dedicated tests: - [`tests/ui/check-cfg/cfg-select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/check-cfg/cfg-select.rs)tests that warnings are emitted when an unexpected `cfg` condition is used. - [`tests/ui/macros/cfg_select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/macros/cfg_select.rs) tests that `cfg_select!` has the expected expansion, and tests that the expected syntax is accepted. ## History - rust-lang#115416 - rust-lang#117162 - rust-lang#133720 - rust-lang#135625 - rust-lang#137198 - rust-lang#138993 - rust-lang#138996 - rust-lang#143461 - rust-lang#143941 - rust-lang#145233 - rust-lang#148712 - rust-lang#149380 - rust-lang#149925 # Resolved questions # Unresolved questions The style team has decided on how to format `cfg_select!`, but this formatting has not yet been implemented. See rust-lang#144323. r? @traviscross   > [!NOTE] > # Concerns (0 active) > > - ~~[allowing-comma-after-closing-brace](rust-lang#149783 (comment) resolved in [this comment](rust-lang#149783 (comment)) > > *Managed by `@rustbot`—see [help](https://forge.rust-lang.org/triagebot/concern.html) for details.*

@traviscross

…=JonathanBrouwer stabilize `cfg_select!` *[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/149783)* tracking issue: rust-lang#115585 closes rust-lang#115585 reference PR: - rust-lang/reference#2103 # Request for Stabilization ## Summary The `cfg_select!` macro picks the expansion corresponding to the first `cfg` condition that evaluates to `true`. It simplifies complex conditional expressions. ```rust cfg_select! { unix => { fn foo() { /* unix specific functionality */ } } target_pointer_width = "32" => { fn foo() { /* non-unix, 32-bit functionality */ } } _ => { fn foo() { /* fallback implementation */ } } } let is_unix_str = cfg_select! { unix => "unix", _ => "not unix", }; println!("{is_unix_str}"); ``` ## Semantics The expansion of a `cfg_select!` call is the right-hand side of the first `cfg` rule that evaluates to true. This can be roughly expressed using this macro: ```rust macro_rules! cfg_select { ({ $($tt:tt)* }) => {{ $crate::cfg_select! { $($tt)* } }}; (_ => { $($output:tt)* }) => { $($output)* }; ( $cfg:meta => $output:tt $($( $rest:tt )+)? ) => { #[cfg($cfg)] $crate::cfg_select! { _ => $output } $( #[cfg(not($cfg))] $crate::cfg_select! { $($rest)+ } )? } } ``` The actual implementation uses a builtin macro so that `cfg_select!` can be used both in item and expression position. ## Documentation reference PR: - rust-lang/reference#2103 ## Tests The `cfg_select!` macro is already used extensively in the rust compiler codebase. It has several dedicated tests: - [`tests/ui/check-cfg/cfg-select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/check-cfg/cfg-select.rs)tests that warnings are emitted when an unexpected `cfg` condition is used. - [`tests/ui/macros/cfg_select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/macros/cfg_select.rs) tests that `cfg_select!` has the expected expansion, and tests that the expected syntax is accepted. ## History - rust-lang#115416 - rust-lang#117162 - rust-lang#133720 - rust-lang#135625 - rust-lang#137198 - rust-lang#138993 - rust-lang#138996 - rust-lang#143461 - rust-lang#143941 - rust-lang#145233 - rust-lang#148712 - rust-lang#149380 - rust-lang#149925 # Resolved questions # Unresolved questions The style team has decided on how to format `cfg_select!`, but this formatting has not yet been implemented. See rust-lang#144323. r? @traviscross   > [!NOTE] > # Concerns (0 active) > > - ~~[allowing-comma-after-closing-brace](rust-lang#149783 (comment) resolved in [this comment](rust-lang#149783 (comment)) > > *Managed by `@rustbot`—see [help](https://forge.rust-lang.org/triagebot/concern.html) for details.*

@traviscross

…=JonathanBrouwer stabilize `cfg_select!` *[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/149783)* tracking issue: rust-lang#115585 closes rust-lang#115585 reference PR: - rust-lang/reference#2103 # Request for Stabilization ## Summary The `cfg_select!` macro picks the expansion corresponding to the first `cfg` condition that evaluates to `true`. It simplifies complex conditional expressions. ```rust cfg_select! { unix => { fn foo() { /* unix specific functionality */ } } target_pointer_width = "32" => { fn foo() { /* non-unix, 32-bit functionality */ } } _ => { fn foo() { /* fallback implementation */ } } } let is_unix_str = cfg_select! { unix => "unix", _ => "not unix", }; println!("{is_unix_str}"); ``` ## Semantics The expansion of a `cfg_select!` call is the right-hand side of the first `cfg` rule that evaluates to true. This can be roughly expressed using this macro: ```rust macro_rules! cfg_select { ({ $($tt:tt)* }) => {{ $crate::cfg_select! { $($tt)* } }}; (_ => { $($output:tt)* }) => { $($output)* }; ( $cfg:meta => $output:tt $($( $rest:tt )+)? ) => { #[cfg($cfg)] $crate::cfg_select! { _ => $output } $( #[cfg(not($cfg))] $crate::cfg_select! { $($rest)+ } )? } } ``` The actual implementation uses a builtin macro so that `cfg_select!` can be used both in item and expression position. ## Documentation reference PR: - rust-lang/reference#2103 ## Tests The `cfg_select!` macro is already used extensively in the rust compiler codebase. It has several dedicated tests: - [`tests/ui/check-cfg/cfg-select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/check-cfg/cfg-select.rs)tests that warnings are emitted when an unexpected `cfg` condition is used. - [`tests/ui/macros/cfg_select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/macros/cfg_select.rs) tests that `cfg_select!` has the expected expansion, and tests that the expected syntax is accepted. ## History - rust-lang#115416 - rust-lang#117162 - rust-lang#133720 - rust-lang#135625 - rust-lang#137198 - rust-lang#138993 - rust-lang#138996 - rust-lang#143461 - rust-lang#143941 - rust-lang#145233 - rust-lang#148712 - rust-lang#149380 - rust-lang#149925 # Resolved questions # Unresolved questions The style team has decided on how to format `cfg_select!`, but this formatting has not yet been implemented. See rust-lang#144323. r? @traviscross   > [!NOTE] > # Concerns (0 active) > > - ~~[allowing-comma-after-closing-brace](rust-lang#149783 (comment) resolved in [this comment](rust-lang#149783 (comment)) > > *Managed by `@rustbot`—see [help](https://forge.rust-lang.org/triagebot/concern.html) for details.*

@traviscross

Rollup merge of #149783 - folkertdev:stabilize-cfg-select, r=JonathanBrouwer stabilize `cfg_select!` *[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/149783)* tracking issue: #115585 closes #115585 reference PR: - rust-lang/reference#2103 # Request for Stabilization ## Summary The `cfg_select!` macro picks the expansion corresponding to the first `cfg` condition that evaluates to `true`. It simplifies complex conditional expressions. ```rust cfg_select! { unix => { fn foo() { /* unix specific functionality */ } } target_pointer_width = "32" => { fn foo() { /* non-unix, 32-bit functionality */ } } _ => { fn foo() { /* fallback implementation */ } } } let is_unix_str = cfg_select! { unix => "unix", _ => "not unix", }; println!("{is_unix_str}"); ``` ## Semantics The expansion of a `cfg_select!` call is the right-hand side of the first `cfg` rule that evaluates to true. This can be roughly expressed using this macro: ```rust macro_rules! cfg_select { ({ $($tt:tt)* }) => {{ $crate::cfg_select! { $($tt)* } }}; (_ => { $($output:tt)* }) => { $($output)* }; ( $cfg:meta => $output:tt $($( $rest:tt )+)? ) => { #[cfg($cfg)] $crate::cfg_select! { _ => $output } $( #[cfg(not($cfg))] $crate::cfg_select! { $($rest)+ } )? } } ``` The actual implementation uses a builtin macro so that `cfg_select!` can be used both in item and expression position. ## Documentation reference PR: - rust-lang/reference#2103 ## Tests The `cfg_select!` macro is already used extensively in the rust compiler codebase. It has several dedicated tests: - [`tests/ui/check-cfg/cfg-select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/check-cfg/cfg-select.rs)tests that warnings are emitted when an unexpected `cfg` condition is used. - [`tests/ui/macros/cfg_select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/macros/cfg_select.rs) tests that `cfg_select!` has the expected expansion, and tests that the expected syntax is accepted. ## History - #115416 - #117162 - #133720 - #135625 - #137198 - #138993 - #138996 - #143461 - #143941 - #145233 - #148712 - #149380 - #149925 # Resolved questions # Unresolved questions The style team has decided on how to format `cfg_select!`, but this formatting has not yet been implemented. See #144323. r? @traviscross   > [!NOTE] > # Concerns (0 active) > > - ~~[allowing-comma-after-closing-brace](#149783 (comment) resolved in [this comment](#149783 (comment)) > > *Managed by `@rustbot`—see [help](https://forge.rust-lang.org/triagebot/concern.html) for details.*

@traviscross

…Brouwer stabilize `cfg_select!` *[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/149783)* tracking issue: rust-lang/rust#115585 closes rust-lang/rust#115585 reference PR: - rust-lang/reference#2103 # Request for Stabilization ## Summary The `cfg_select!` macro picks the expansion corresponding to the first `cfg` condition that evaluates to `true`. It simplifies complex conditional expressions. ```rust cfg_select! { unix => { fn foo() { /* unix specific functionality */ } } target_pointer_width = "32" => { fn foo() { /* non-unix, 32-bit functionality */ } } _ => { fn foo() { /* fallback implementation */ } } } let is_unix_str = cfg_select! { unix => "unix", _ => "not unix", }; println!("{is_unix_str}"); ``` ## Semantics The expansion of a `cfg_select!` call is the right-hand side of the first `cfg` rule that evaluates to true. This can be roughly expressed using this macro: ```rust macro_rules! cfg_select { ({ $($tt:tt)* }) => {{ $crate::cfg_select! { $($tt)* } }}; (_ => { $($output:tt)* }) => { $($output)* }; ( $cfg:meta => $output:tt $($( $rest:tt )+)? ) => { #[cfg($cfg)] $crate::cfg_select! { _ => $output } $( #[cfg(not($cfg))] $crate::cfg_select! { $($rest)+ } )? } } ``` The actual implementation uses a builtin macro so that `cfg_select!` can be used both in item and expression position. ## Documentation reference PR: - rust-lang/reference#2103 ## Tests The `cfg_select!` macro is already used extensively in the rust compiler codebase. It has several dedicated tests: - [`tests/ui/check-cfg/cfg-select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/check-cfg/cfg-select.rs)tests that warnings are emitted when an unexpected `cfg` condition is used. - [`tests/ui/macros/cfg_select.rs`](https://github.com/rust-lang/rust/blob/main/tests/ui/macros/cfg_select.rs) tests that `cfg_select!` has the expected expansion, and tests that the expected syntax is accepted. ## History - rust-lang/rust#115416 - rust-lang/rust#117162 - rust-lang/rust#133720 - rust-lang/rust#135625 - rust-lang/rust#137198 - rust-lang/rust#138993 - rust-lang/rust#138996 - rust-lang/rust#143461 - rust-lang/rust#143941 - rust-lang/rust#145233 - rust-lang/rust#148712 - rust-lang/rust#149380 - rust-lang/rust#149925 # Resolved questions # Unresolved questions The style team has decided on how to format `cfg_select!`, but this formatting has not yet been implemented. See rust-lang/rust#144323. r? @traviscross   > [!NOTE] > # Concerns (0 active) > > - ~~[allowing-comma-after-closing-brace](rust-lang/rust#149783 (comment) resolved in [this comment](rust-lang/rust#149783 (comment)) > > *Managed by `@rustbot`—see [help](https://forge.rust-lang.org/triagebot/concern.html) for details.*

Remove cfg_match from the prelude

0b96e47

rustbot assigned joshtriplett Oct 25, 2023

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Oct 25, 2023

c410-f3r mentioned this pull request Oct 25, 2023

Add the cfg_match! macro #115416

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Amanieu added the beta-nominated Nominated for backporting to the compiler in the beta channel. label Oct 25, 2023

rustbot added the beta-accepted Accepted for backporting to the compiler in the beta channel. label Oct 25, 2023

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-review Status: Awaiting review from the assignee but also interested parties. labels Oct 28, 2023

workingjubilee assigned workingjubilee and unassigned joshtriplett Oct 28, 2023

workingjubilee added a commit to workingjubilee/rustc that referenced this pull request Oct 28, 2023

Rollup merge of rust-lang#117162 - c410-f3r:try, r=workingjubilee

16b2b9a

Remove `cfg_match` from the prelude Fixes rust-lang#117057 cc rust-lang#115585

workingjubilee mentioned this pull request Oct 28, 2023

Rollup of 8 pull requests #117333

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workingjubilee mentioned this pull request Oct 29, 2023

Rollup of 5 pull requests #117335

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bors merged commit 61cd3d0 into rust-lang:master Oct 29, 2023

rustbot added this to the 1.75.0 milestone Oct 29, 2023

rust-timer added a commit to rust-lang-ci/rust that referenced this pull request Oct 29, 2023

Unrolled build for rust-lang#117162

c6d9604

Rollup merge of rust-lang#117162 - c410-f3r:try, r=workingjubilee Remove `cfg_match` from the prelude Fixes rust-lang#117057 cc rust-lang#115585

github-actions bot mentioned this pull request Oct 31, 2023

Automated pull from upstream master ferrocene/ferrocene#74

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cuviper mentioned this pull request Nov 6, 2023

[beta] backports #117644

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cuviper modified the milestones: 1.75.0, 1.74.0 Nov 6, 2023

cuviper removed the beta-nominated Nominated for backporting to the compiler in the beta channel. label Nov 6, 2023

jieyouxu added the F-cfg_select `#![feature(cfg_select)]` label Aug 14, 2025

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Tracking issue for cfg_select (formerly cfg_match) #115585

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folkertdev mentioned this pull request Dec 8, 2025

stabilize cfg_select! #149783

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Remove `cfg_match` from the prelude#117162

Remove `cfg_match` from the prelude#117162
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