refactor(ast): order AST type fields in visitation order (#3228)

Reorder the fields in a couple of AST types.

`walk_*` functions in `oxc_traverse` visit the fields in the order they appear in AST. So this change means that decorators are visited before classes and methods that they decorate.

crates/oxc_ast/src/ast/js.rs

@@ -2343,13 +2343,13 @@ pub struct Class<'a> {
     pub r#type: ClassType,
     #[cfg_attr(feature = "serialize", serde(flatten))]
     pub span: Span,
+    pub decorators: Vec<'a, Decorator<'a>>,
     pub id: Option<BindingIdentifier<'a>>,
     pub super_class: Option<Expression<'a>>,
     pub body: Box<'a, ClassBody<'a>>,
     pub type_parameters: Option<Box<'a, TSTypeParameterDeclaration<'a>>>,
     pub super_type_parameters: Option<Box<'a, TSTypeParameterInstantiation<'a>>>,
     pub implements: Option<Vec<'a, TSClassImplements<'a>>>,
-    pub decorators: Vec<'a, Decorator<'a>>,
     /// Valid Modifiers: `export`, `abstract`
     pub modifiers: Modifiers<'a>,
 }
@@ -2499,6 +2499,7 @@ pub struct MethodDefinition<'a> {
     pub r#type: MethodDefinitionType,
     #[cfg_attr(feature = "serialize", serde(flatten))]
     pub span: Span,
+    pub decorators: Vec<'a, Decorator<'a>>,
     pub key: PropertyKey<'a>,
     pub value: Box<'a, Function<'a>>, // FunctionExpression
     pub kind: MethodDefinitionKind,
@@ -2507,7 +2508,6 @@ pub struct MethodDefinition<'a> {
     pub r#override: bool,
     pub optional: bool,
     pub accessibility: Option<TSAccessibility>,
-    pub decorators: Vec<'a, Decorator<'a>>,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]

crates/oxc_ast/src/ast_builder.rs

@@ -937,13 +937,13 @@ impl<'a> AstBuilder<'a> {
         self.alloc(Class {
             r#type,
             span,
+            decorators,
             id,
             super_class,
             body,
             type_parameters,
             super_type_parameters,
             implements,
-            decorators,
             modifiers,
         })
     }

crates/oxc_traverse/src/walk.rs

@@ -2346,10 +2346,16 @@ pub(crate) unsafe fn walk_class<'a, Tr: Traverse<'a>>(
     ctx: &mut TraverseCtx<'a>,
 ) {
     traverser.enter_class(&mut *node, ctx);
-    ctx.push_stack(Ancestor::ClassId(ancestor::ClassWithoutId(node)));
+    ctx.push_stack(Ancestor::ClassDecorators(ancestor::ClassWithoutDecorators(node)));
+    for item in (*((node as *mut u8).add(ancestor::OFFSET_CLASS_DECORATORS) as *mut Vec<Decorator>))
+        .iter_mut()
+    {
+        walk_decorator(traverser, item as *mut _, ctx);
+    }
     if let Some(field) =
         &mut *((node as *mut u8).add(ancestor::OFFSET_CLASS_ID) as *mut Option<BindingIdentifier>)
     {
+        ctx.retag_stack(AncestorType::ClassId);
         walk_binding_identifier(traverser, field as *mut _, ctx);
     }
     if let Some(field) =
@@ -2385,12 +2391,6 @@ pub(crate) unsafe fn walk_class<'a, Tr: Traverse<'a>>(
             walk_ts_class_implements(traverser, item as *mut _, ctx);
         }
     }
-    ctx.retag_stack(AncestorType::ClassDecorators);
-    for item in (*((node as *mut u8).add(ancestor::OFFSET_CLASS_DECORATORS) as *mut Vec<Decorator>))
-        .iter_mut()
-    {
-        walk_decorator(traverser, item as *mut _, ctx);
-    }
     ctx.pop_stack();
     traverser.exit_class(&mut *node, ctx);
 }
@@ -2444,7 +2444,16 @@ pub(crate) unsafe fn walk_method_definition<'a, Tr: Traverse<'a>>(
     ctx: &mut TraverseCtx<'a>,
 ) {
     traverser.enter_method_definition(&mut *node, ctx);
-    ctx.push_stack(Ancestor::MethodDefinitionKey(ancestor::MethodDefinitionWithoutKey(node)));
+    ctx.push_stack(Ancestor::MethodDefinitionDecorators(
+        ancestor::MethodDefinitionWithoutDecorators(node),
+    ));
+    for item in (*((node as *mut u8).add(ancestor::OFFSET_METHOD_DEFINITION_DECORATORS)
+        as *mut Vec<Decorator>))
+        .iter_mut()
+    {
+        walk_decorator(traverser, item as *mut _, ctx);
+    }
+    ctx.retag_stack(AncestorType::MethodDefinitionKey);
     walk_property_key(
         traverser,
         (node as *mut u8).add(ancestor::OFFSET_METHOD_DEFINITION_KEY) as *mut PropertyKey,
@@ -2457,13 +2466,6 @@ pub(crate) unsafe fn walk_method_definition<'a, Tr: Traverse<'a>>(
             as *mut Box<Function>)) as *mut _,
         ctx,
     );
-    ctx.retag_stack(AncestorType::MethodDefinitionDecorators);
-    for item in (*((node as *mut u8).add(ancestor::OFFSET_METHOD_DEFINITION_DECORATORS)
-        as *mut Vec<Decorator>))
-        .iter_mut()
-    {
-        walk_decorator(traverser, item as *mut _, ctx);
-    }
     ctx.pop_stack();
     traverser.exit_method_definition(&mut *node, ctx);
 }