NoArgsAttributeParser: use an assoc const instead

compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs

@@ -49,10 +49,7 @@ pub(crate) struct ColdParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ColdParser {
     const PATH: &[Symbol] = &[sym::cold];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
-
-    fn create(span: Span) -> AttributeKind {
-        AttributeKind::Cold(span)
-    }
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::Cold;
 }
 
 pub(crate) struct ExportNameParser;
@@ -193,20 +190,14 @@ pub(crate) struct TrackCallerParser;
 impl<S: Stage> NoArgsAttributeParser<S> for TrackCallerParser {
     const PATH: &[Symbol] = &[sym::track_caller];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
-
-    fn create(span: Span) -> AttributeKind {
-        AttributeKind::TrackCaller(span)
-    }
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::TrackCaller;
 }
 
 pub(crate) struct NoMangleParser;
 impl<S: Stage> NoArgsAttributeParser<S> for NoMangleParser {
     const PATH: &[Symbol] = &[sym::no_mangle];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
-
-    fn create(span: Span) -> AttributeKind {
-        AttributeKind::NoMangle(span)
-    }
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::NoMangle;
 }
 
 #[derive(Default)]

compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs

@@ -8,18 +8,12 @@ pub(crate) struct AsPtrParser;
 impl<S: Stage> NoArgsAttributeParser<S> for AsPtrParser {
     const PATH: &[Symbol] = &[sym::rustc_as_ptr];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
-
-    fn create(span: Span) -> AttributeKind {
-        AttributeKind::AsPtr(span)
-    }
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::AsPtr;
 }
 
 pub(crate) struct PubTransparentParser;
 impl<S: Stage> NoArgsAttributeParser<S> for PubTransparentParser {
     const PATH: &[Symbol] = &[sym::rustc_pub_transparent];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
-
-    fn create(span: Span) -> AttributeKind {
-        AttributeKind::PubTransparent(span)
-    }
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::PubTransparent;
 }

compiler/rustc_attr_parsing/src/attributes/loop_match.rs

@@ -8,18 +8,12 @@ pub(crate) struct LoopMatchParser;
 impl<S: Stage> NoArgsAttributeParser<S> for LoopMatchParser {
     const PATH: &[Symbol] = &[sym::loop_match];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
-
-    fn create(span: Span) -> AttributeKind {
-        AttributeKind::LoopMatch(span)
-    }
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::LoopMatch;
 }
 
 pub(crate) struct ConstContinueParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ConstContinueParser {
     const PATH: &[Symbol] = &[sym::const_continue];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
-
-    fn create(span: Span) -> AttributeKind {
-        AttributeKind::ConstContinue(span)
-    }
+    const CREATE: fn(Span) -> AttributeKind = AttributeKind::ConstContinue;
 }

compiler/rustc_attr_parsing/src/attributes/mod.rs

@@ -238,7 +238,7 @@ pub(crate) trait NoArgsAttributeParser<S: Stage>: 'static {
     const ON_DUPLICATE: OnDuplicate<S>;
 
     /// Create the [`AttributeKind`] given attribute's [`Span`].
-    fn create(span: Span) -> AttributeKind;
+    const CREATE: fn(Span) -> AttributeKind;
 }
 
 pub(crate) struct WithoutArgs<T: NoArgsAttributeParser<S>, S: Stage>(PhantomData<(S, T)>);
@@ -259,7 +259,7 @@ impl<T: NoArgsAttributeParser<S>, S: Stage> SingleAttributeParser<S> for Without
         if let Err(span) = args.no_args() {
             cx.expected_no_args(span);
         }
-        Some(T::create(cx.attr_span))
+        Some(T::CREATE(cx.attr_span))
     }
 }
 

compiler/rustc_attr_parsing/src/attributes/semantics.rs

@@ -8,8 +8,5 @@ pub(crate) struct MayDangleParser;
 impl<S: Stage> NoArgsAttributeParser<S> for MayDangleParser {
     const PATH: &[Symbol] = &[sym::may_dangle];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
-
-    fn create(span: Span) -> AttributeKind {
-        AttributeKind::MayDangle(span)
-    }
+    const CREATE: fn(span: Span) -> AttributeKind = AttributeKind::MayDangle;
 }

compiler/rustc_attr_parsing/src/attributes/stability.rs

@@ -136,10 +136,7 @@ pub(crate) struct ConstStabilityIndirectParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ConstStabilityIndirectParser {
     const PATH: &[Symbol] = &[sym::rustc_const_stable_indirect];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Ignore;
-
-    fn create(_: Span) -> AttributeKind {
-        AttributeKind::ConstStabilityIndirect
-    }
+    const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::ConstStabilityIndirect;
 }
 
 #[derive(Default)]