Auto merge of #57332 - Dylan-DPC:feature/stabilise-cfg-attr, r=Centril

stabilize cfg_attr_multi

Stabilizes cfg_attr_multi feature

Related to #54881

Will add the lint in a seperate PR

r? @Centril

src/libsyntax/config.rs

@@ -5,7 +5,6 @@ use feature_gate::{
     Features,
     get_features,
     GateIssue,
-    emit_feature_err,
 };
 use {fold, attr};
 use ast;
@@ -94,13 +93,6 @@ impl<'a> StripUnconfigured<'a> {
             return vec![attr];
         }
 
-        let gate_cfg_attr_multi = if let Some(ref features) = self.features {
-            !features.cfg_attr_multi
-        } else {
-            false
-        };
-        let cfg_attr_span = attr.span;
-
         let (cfg_predicate, expanded_attrs) = match attr.parse(self.sess, |parser| {
             parser.expect(&token::OpenDelim(token::Paren))?;
 
@@ -130,21 +122,8 @@ impl<'a> StripUnconfigured<'a> {
         // Check feature gate and lint on zero attributes in source. Even if the feature is gated,
         // we still compute as if it wasn't, since the emitted error will stop compilation further
         // along the compilation.
-        match (expanded_attrs.len(), gate_cfg_attr_multi) {
-            (0, false) => {
-                // FIXME: Emit unused attribute lint here.
-            },
-            (1, _) => {},
-            (_, true) => {
-                emit_feature_err(
-                    self.sess,
-                    "cfg_attr_multi",
-                    cfg_attr_span,
-                    GateIssue::Language,
-                    "cfg_attr with zero or more than one attributes is experimental",
-                );
-            },
-            (_, false) => {}
+        if expanded_attrs.len() == 0 {
+            // FIXME: Emit unused attribute lint here.
         }
 
         if attr::cfg_matches(&cfg_predicate, self.sess, self.features) {

src/libsyntax/feature_gate.rs

@@ -465,9 +465,6 @@ declare_features! (
     // Allows `impl Trait` in bindings (`let`, `const`, `static`).
     (active, impl_trait_in_bindings, "1.30.0", Some(34511), None),
 
-    // `#[cfg_attr(predicate, multiple, attributes, here)]`
-    (active, cfg_attr_multi, "1.31.0", Some(54881), None),
-
     // Allows `const _: TYPE = VALUE`.
     (active, underscore_const_names, "1.31.0", Some(54912), None),
 
@@ -689,6 +686,8 @@ declare_features! (
     (accepted, repr_packed, "1.33.0", Some(33158), None),
     // Allows calling `const unsafe fn` inside `unsafe` blocks in `const fn` functions.
     (accepted, min_const_unsafe_fn, "1.33.0", Some(55607), None),
+    // `#[cfg_attr(predicate, multiple, attributes, here)]`
+    (accepted, cfg_attr_multi, "1.33.0", Some(54881), None),
 );
 
 // If you change this, please modify `src/doc/unstable-book` as well. You must

src/test/ui/conditional-compilation/cfg-attr-multi-false.rs

@@ -4,7 +4,6 @@
 // compile-pass
 
 #![warn(unused_must_use)]
-#![feature(cfg_attr_multi)]
 
 #[cfg_attr(any(), deprecated, must_use)]
 struct Struct {}

src/test/ui/conditional-compilation/cfg-attr-multi-invalid-1.rs

@@ -1,6 +1,5 @@
 // compile-flags: --cfg broken
 
-#![feature(cfg_attr_multi)]
 #![crate_type = "lib"]
 #![cfg_attr(broken, no_core, no_std)] //~ ERROR no_core is experimental
 

src/test/ui/conditional-compilation/cfg-attr-multi-invalid-1.stderr

@@ -1,5 +1,5 @@
 error[E0658]: no_core is experimental (see issue #29639)
-  --> $DIR/cfg-attr-multi-invalid-1.rs:5:21
+  --> $DIR/cfg-attr-multi-invalid-1.rs:4:21
    |
 LL | #![cfg_attr(broken, no_core, no_std)] //~ ERROR no_core is experimental
    |                     ^^^^^^^

src/test/ui/conditional-compilation/cfg-attr-multi-invalid-2.rs

@@ -1,6 +1,5 @@
 // compile-flags: --cfg broken
 
-#![feature(cfg_attr_multi)]
 #![crate_type = "lib"]
 #![cfg_attr(broken, no_std, no_core)] //~ ERROR no_core is experimental
 

src/test/ui/conditional-compilation/cfg-attr-multi-invalid-2.stderr

@@ -1,5 +1,5 @@
 error[E0658]: no_core is experimental (see issue #29639)
-  --> $DIR/cfg-attr-multi-invalid-2.rs:5:29
+  --> $DIR/cfg-attr-multi-invalid-2.rs:4:29
    |
 LL | #![cfg_attr(broken, no_std, no_core)] //~ ERROR no_core is experimental
    |                             ^^^^^^^

src/test/ui/conditional-compilation/cfg-attr-multi-true.rs

@@ -5,7 +5,6 @@
 // compile-pass
 
 #![warn(unused_must_use)]
-#![feature(cfg_attr_multi)]
 
 #[cfg_attr(all(), deprecated, must_use)]
 struct MustUseDeprecated {}

src/test/ui/conditional-compilation/cfg-attr-multi-true.stderr

@@ -1,31 +1,31 @@
 warning: use of deprecated item 'MustUseDeprecated'
-  --> $DIR/cfg-attr-multi-true.rs:13:6
+  --> $DIR/cfg-attr-multi-true.rs:12:6
    |
 LL | impl MustUseDeprecated { //~ warning: use of deprecated item
    |      ^^^^^^^^^^^^^^^^^
    |
    = note: #[warn(deprecated)] on by default
 
 warning: use of deprecated item 'MustUseDeprecated'
-  --> $DIR/cfg-attr-multi-true.rs:20:5
+  --> $DIR/cfg-attr-multi-true.rs:19:5
    |
 LL |     MustUseDeprecated::new(); //~ warning: use of deprecated item
    |     ^^^^^^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'MustUseDeprecated'
-  --> $DIR/cfg-attr-multi-true.rs:14:17
+  --> $DIR/cfg-attr-multi-true.rs:13:17
    |
 LL |     fn new() -> MustUseDeprecated { //~ warning: use of deprecated item
    |                 ^^^^^^^^^^^^^^^^^
 
 warning: use of deprecated item 'MustUseDeprecated'
-  --> $DIR/cfg-attr-multi-true.rs:15:9
+  --> $DIR/cfg-attr-multi-true.rs:14:9
    |
 LL |         MustUseDeprecated {} //~ warning: use of deprecated item
    |         ^^^^^^^^^^^^^^^^^
 
 warning: unused `MustUseDeprecated` that must be used
-  --> $DIR/cfg-attr-multi-true.rs:20:5
+  --> $DIR/cfg-attr-multi-true.rs:19:5
    |
 LL |     MustUseDeprecated::new(); //~ warning: use of deprecated item
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^

src/test/ui/conditional-compilation/cfg-attr-parse.rs

@@ -1,7 +1,5 @@
 // Parse `cfg_attr` with varying numbers of attributes and trailing commas
 
-#![feature(cfg_attr_multi)]
-
 // Completely empty `cfg_attr` input
 #[cfg_attr()] //~ error: expected identifier, found `)`
 struct NoConfigurationPredicate;

src/test/ui/conditional-compilation/cfg-attr-parse.stderr

@@ -1,29 +1,29 @@
 error: expected identifier, found `)`
-  --> $DIR/cfg-attr-parse.rs:6:12
+  --> $DIR/cfg-attr-parse.rs:4:12
    |
 LL | #[cfg_attr()] //~ error: expected identifier, found `)`
    |            ^ expected identifier
 
 error: expected `,`, found `)`
-  --> $DIR/cfg-attr-parse.rs:10:17
+  --> $DIR/cfg-attr-parse.rs:8:17
    |
 LL | #[cfg_attr(all())] //~ error: expected `,`, found `)`
    |                 ^ expected `,`
 
 error: expected identifier, found `,`
-  --> $DIR/cfg-attr-parse.rs:18:18
+  --> $DIR/cfg-attr-parse.rs:16:18
    |
 LL | #[cfg_attr(all(),,)] //~ ERROR expected identifier
    |                  ^ expected identifier
 
 error: expected identifier, found `,`
-  --> $DIR/cfg-attr-parse.rs:30:28
+  --> $DIR/cfg-attr-parse.rs:28:28
    |
 LL | #[cfg_attr(all(), must_use,,)] //~ ERROR expected identifier
    |                            ^ expected identifier
 
 error: expected identifier, found `,`
-  --> $DIR/cfg-attr-parse.rs:42:40
+  --> $DIR/cfg-attr-parse.rs:40:40
    |
 LL | #[cfg_attr(all(), must_use, deprecated,,)] //~ ERROR expected identifier
    |                                        ^ expected identifier