Fix incorrect attributes logic, remove feature

Author: aerooneqq

compiler/rustc_ast_lowering/src/delegation/attributes.rs

@@ -61,24 +61,26 @@ impl<'hir> LoweringContext<'_, 'hir> {
         &self,
         span: Span,
         sig_id: DefId,
-        existing_attrs: Option<&&[hir::Attribute]>,
+        existing: Option<&&[hir::Attribute]>,
     ) -> Vec<hir::Attribute> {
         ADDITIONS
             .iter()
             .filter_map(|addition_info| {
-                existing_attrs
-                    .filter(|attrs| attrs.iter().any(|a| (addition_info.equals)(a)))
-                    .and_then(|_| match addition_info.kind {
-                        AdditionKind::Default { factory } => Some(factory(span)),
-                        AdditionKind::Inherit { factory, .. } =>
-                        {
-                            #[allow(deprecated)]
-                            self.tcx
-                                .get_all_attrs(sig_id)
-                                .iter()
-                                .find_map(|a| (addition_info.equals)(a).then(|| factory(span, a)))
-                        }
-                    })
+                if existing.is_some_and(|attrs| attrs.iter().any(|a| (addition_info.equals)(a))) {
+                    return None;
+                }
+
+                match addition_info.kind {
+                    AdditionKind::Default { factory } => Some(factory(span)),
+                    AdditionKind::Inherit { factory, .. } =>
+                    {
+                        #[allow(deprecated)]
+                        self.tcx
+                            .get_all_attrs(sig_id)
+                            .iter()
+                            .find_map(|a| (addition_info.equals)(a).then(|| factory(span, a)))
+                    }
+                }
             })
             .collect::<Vec<_>>()
     }

compiler/rustc_ast_lowering/src/lib.rs

@@ -31,7 +31,6 @@
 //! in the HIR, especially for multiple identifiers.
 
 // tidy-alphabetical-start
-#![feature(bool_to_result)]
 #![feature(const_default)]
 #![feature(const_trait_impl)]
 #![feature(default_field_values)]