Rename cfg_match! to cfg_select!

tgross35 · tgross35 · commit 3a231bf4ac55 · 2025-02-18T00:27:30.000Z
At [1] it was pointed out that `cfg_match!` syntax does not actually align well with match syntax, which is a possible source of confusion. The comment points out that usage is instead more similar to ecosystem `select!` macros. Rename `cfg_match!` to `cfg_select!` to match this. Tracking issue: #115585 [1]: #115585 (comment)
diff --git a/compiler/rustc_codegen_cranelift/patches/0027-coretests-128bit-atomic-operations.patch b/compiler/rustc_codegen_cranelift/patches/0027-coretests-128bit-atomic-operations.patch
@@ -17,7 +17,7 @@ index 1e336bf..35e6f54 100644
 @@ -2,5 +2,4 @@
  // tidy-alphabetical-start
 -#![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
- #![cfg_attr(test, feature(cfg_match))]
+ #![cfg_attr(test, feature(cfg_select))]
  #![feature(alloc_layout_extra)]
  #![feature(array_chunks)]
 diff --git a/tests/atomic.rs b/tests/atomic.rs
diff --git a/compiler/rustc_codegen_gcc/patches/0022-core-Disable-not-compiling-tests.patch b/compiler/rustc_codegen_gcc/patches/0022-core-Disable-not-compiling-tests.patch
@@ -37,7 +37,7 @@ index a4a7946..ecfe43f 100644
  // tidy-alphabetical-start
 +#![cfg(test)]
  #![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
- #![cfg_attr(test, feature(cfg_match))]
+ #![cfg_attr(test, feature(cfg_select))]
  #![feature(alloc_layout_extra)]
 -- 
 2.47.1
diff --git a/compiler/rustc_data_structures/src/flock.rs b/compiler/rustc_data_structures/src/flock.rs
@@ -29,7 +29,7 @@ cfg_match! {
 }
 
 #[cfg(not(bootstrap))]
-cfg_match! {
+cfg_select! {
     target_os = "linux" => {
         mod linux;
         use linux as imp;
diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
@@ -10,6 +10,8 @@
 #![allow(internal_features)]
 #![allow(rustc::default_hash_types)]
 #![allow(rustc::potential_query_instability)]
+#![cfg_attr(bootstrap, feature(cfg_match))]
+#![cfg_attr(not(bootstrap), feature(cfg_select))]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
@@ -19,7 +21,6 @@
 #![feature(ascii_char_variants)]
 #![feature(assert_matches)]
 #![feature(auto_traits)]
-#![feature(cfg_match)]
 #![feature(core_intrinsics)]
 #![feature(dropck_eyepatch)]
 #![feature(extend_one)]
diff --git a/compiler/rustc_data_structures/src/profiling.rs b/compiler/rustc_data_structures/src/profiling.rs
@@ -923,7 +923,7 @@ cfg_match! {
 }
 
 #[cfg(not(bootstrap))]
-cfg_match! {
+cfg_select! {
     windows => {
         pub fn get_resident_set_size() -> Option<usize> {
             use std::mem;
diff --git a/compiler/rustc_span/src/analyze_source_file.rs b/compiler/rustc_span/src/analyze_source_file.rs
@@ -155,7 +155,7 @@ cfg_match! {
 }
 
 #[cfg(not(bootstrap))]
-cfg_match! {
+cfg_select! {
     any(target_arch = "x86", target_arch = "x86_64") => {
         fn analyze_source_file_dispatch(
             src: &str,
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
@@ -17,10 +17,11 @@
 
 // tidy-alphabetical-start
 #![allow(internal_features)]
+#![cfg_attr(bootstrap, feature(cfg_match))]
+#![cfg_attr(not(bootstrap), feature(cfg_select))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(array_windows)]
-#![feature(cfg_match)]
 #![feature(core_io_borrowed_buf)]
 #![feature(hash_set_entry)]
 #![feature(if_let_guard)]
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
@@ -251,8 +251,12 @@ pub mod autodiff {
 #[unstable(feature = "contracts", issue = "128044")]
 pub mod contracts;
 
+#[cfg(bootstrap)]
 #[unstable(feature = "cfg_match", issue = "115585")]
 pub use crate::macros::cfg_match;
+#[cfg(not(bootstrap))]
+#[unstable(feature = "cfg_select", issue = "115585")]
+pub use crate::macros::cfg_select;
 
 #[macro_use]
 mod internal_macros;
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
@@ -299,9 +299,9 @@ pub macro cfg_match {
 /// # Example
 ///
 /// ```
-/// #![feature(cfg_match)]
+/// #![feature(cfg_select)]
 ///
-/// cfg_match! {
+/// cfg_select! {
 ///     unix => {
 ///         fn foo() { /* unix specific functionality */ }
 ///     }
@@ -317,19 +317,19 @@ pub macro cfg_match {
 /// If desired, it is possible to return expressions through the use of surrounding braces:
 ///
 /// ```
-/// #![feature(cfg_match)]
+/// #![feature(cfg_select)]
 ///
-/// let _some_string = cfg_match! {{
+/// let _some_string = cfg_select! {{
 ///     unix => { "With great power comes great electricity bills" }
 ///     _ => { "Behind every successful diet is an unwatched pizza" }
 /// }};
 /// ```
 #[cfg(not(bootstrap))]
-#[unstable(feature = "cfg_match", issue = "115585")]
-#[rustc_diagnostic_item = "cfg_match"]
-pub macro cfg_match {
+#[unstable(feature = "cfg_select", issue = "115585")]
+#[rustc_diagnostic_item = "cfg_select"]
+pub macro cfg_select {
     ({ $($tt:tt)* }) => {{
-        cfg_match! { $($tt)* }
+        cfg_select! { $($tt)* }
     }},
     (_ => { $($output:tt)* }) => {
         $($output)*
@@ -339,10 +339,10 @@ pub macro cfg_match {
         $($( $rest:tt )+)?
     ) => {
         #[cfg($cfg)]
-        cfg_match! { _ => $output }
+        cfg_select! { _ => $output }
         $(
             #[cfg(not($cfg))]
-            cfg_match! { $($rest)+ }
+            cfg_select! { $($rest)+ }
         )?
     },
 }
diff --git a/library/coretests/tests/lib.rs b/library/coretests/tests/lib.rs
@@ -1,6 +1,6 @@
 // tidy-alphabetical-start
 #![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
-#![cfg_attr(test, feature(cfg_match))]
+#![cfg_attr(test, feature(cfg_select))]
 #![feature(alloc_layout_extra)]
 #![feature(array_chunks)]
 #![feature(array_ptr_get)]
diff --git a/library/coretests/tests/macros.rs b/library/coretests/tests/macros.rs
@@ -9,7 +9,7 @@ trait Trait {
 struct Struct;
 
 impl Trait for Struct {
-    cfg_match! {
+    cfg_select! {
         feature = "blah" => {
             fn blah(&self) {
                 unimplemented!();
@@ -45,22 +45,22 @@ fn matches_leading_pipe() {
 }
 
 #[test]
-fn cfg_match_basic() {
-    cfg_match! {
+fn cfg_select_basic() {
+    cfg_select! {
         target_pointer_width = "64" => { fn f0_() -> bool { true }}
     }
 
-    cfg_match! {
+    cfg_select! {
         unix => { fn f1_() -> bool { true } }
         any(target_os = "macos", target_os = "linux") => { fn f1_() -> bool { false }}
     }
 
-    cfg_match! {
+    cfg_select! {
         target_pointer_width = "32" => { fn f2_() -> bool { false } }
         target_pointer_width = "64" => { fn f2_() -> bool { true } }
     }
 
-    cfg_match! {
+    cfg_select! {
         target_pointer_width = "16" => { fn f3_() -> i32 { 1 } }
         _ => { fn f3_() -> i32 { 2 }}
     }
@@ -81,8 +81,8 @@ fn cfg_match_basic() {
 }
 
 #[test]
-fn cfg_match_debug_assertions() {
-    cfg_match! {
+fn cfg_select_debug_assertions() {
+    cfg_select! {
         debug_assertions => {
             assert!(cfg!(debug_assertions));
             assert_eq!(4, 2+2);
@@ -96,8 +96,8 @@ fn cfg_match_debug_assertions() {
 
 #[cfg(target_pointer_width = "64")]
 #[test]
-fn cfg_match_no_duplication_on_64() {
-    cfg_match! {
+fn cfg_select_no_duplication_on_64() {
+    cfg_select! {
         windows => {
             fn foo() {}
         }
@@ -112,34 +112,34 @@ fn cfg_match_no_duplication_on_64() {
 }
 
 #[test]
-fn cfg_match_options() {
-    cfg_match! {
+fn cfg_select_options() {
+    cfg_select! {
         test => {
             use core::option::Option as Option2;
             fn works1() -> Option2<u32> { Some(1) }
         }
         _ => { fn works1() -> Option<u32> { None } }
     }
 
-    cfg_match! {
+    cfg_select! {
         feature = "foo" => { fn works2() -> bool { false } }
         test => { fn works2() -> bool { true } }
         _ => { fn works2() -> bool { false } }
     }
 
-    cfg_match! {
+    cfg_select! {
         feature = "foo" => { fn works3() -> bool { false } }
         _ => { fn works3() -> bool { true } }
     }
 
-    cfg_match! {
+    cfg_select! {
         test => {
             use core::option::Option as Option3;
             fn works4() -> Option3<u32> { Some(1) }
         }
     }
 
-    cfg_match! {
+    cfg_select! {
         feature = "foo" => { fn works5() -> bool { false } }
         test => { fn works5() -> bool { true } }
     }
@@ -152,8 +152,8 @@ fn cfg_match_options() {
 }
 
 #[test]
-fn cfg_match_two_functions() {
-    cfg_match! {
+fn cfg_select_two_functions() {
+    cfg_select! {
         target_pointer_width = "64" => {
             fn foo1() {}
             fn bar1() {}
@@ -177,7 +177,7 @@ fn cfg_match_two_functions() {
 }
 
 fn _accepts_expressions() -> i32 {
-    cfg_match! {
+    cfg_select! {
         unix => { 1 }
         _ => { 2 }
     }
@@ -188,14 +188,14 @@ fn _accepts_expressions() -> i32 {
 fn _allows_stmt_expr_attributes() {
     let one = 1;
     let two = 2;
-    cfg_match! {
+    cfg_select! {
         unix => { one * two; }
         _ => { one + two; }
     }
 }
 
 fn _expression() {
-    let _ = cfg_match!({
+    let _ = cfg_select!({
         windows => {
             " XP"
         }
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
@@ -690,8 +690,12 @@ mod panicking;
 #[allow(dead_code, unused_attributes, fuzzy_provenance_casts, unsafe_op_in_unsafe_fn)]
 mod backtrace_rs;
 
+#[cfg(bootstrap)]
 #[unstable(feature = "cfg_match", issue = "115585")]
 pub use core::cfg_match;
+#[cfg(not(bootstrap))]
+#[unstable(feature = "cfg_select", issue = "115585")]
+pub use core::cfg_select;
 #[unstable(
     feature = "concat_bytes",
     issue = "87555",

Original file line number	Diff line number	Diff line change
`@@ -29,7 +29,7 @@ cfg_match! {`
`29`	`29`	`}`
`30`	`30`
`31`	`31`	`#[cfg(not(bootstrap))]`
`32`		`-cfg_match! {`
	`32`	`+cfg_select! {`
`33`	`33`	`target_os = "linux" => {`
`34`	`34`	`mod linux;`
`35`	`35`	`use linux as imp;`
Original file line number	Diff line number	Diff line change
`@@ -923,7 +923,7 @@ cfg_match! {`
`923`	`923`	`}`
`924`	`924`
`925`	`925`	`#[cfg(not(bootstrap))]`
`926`		`-cfg_match! {`
	`926`	`+cfg_select! {`
`927`	`927`	`windows => {`
`928`	`928`	`pub fn get_resident_set_size() -> Option<usize> {`
`929`	`929`	`use std::mem;`
Original file line number	Diff line number	Diff line change
`@@ -155,7 +155,7 @@ cfg_match! {`
`155`	`155`	`}`
`156`	`156`
`157`	`157`	`#[cfg(not(bootstrap))]`
`158`		`-cfg_match! {`
	`158`	`+cfg_select! {`
`159`	`159`	`any(target_arch = "x86", target_arch = "x86_64") => {`
`160`	`160`	`fn analyze_source_file_dispatch(`
`161`	`161`	`src: &str,`