Split out ast::ItemKind::Const into its own struct

compiler/rustc_ast/src/ast.rs

@@ -2897,6 +2897,13 @@ pub struct Static {
     pub expr: Option<P<Expr>>,
 }
 
+#[derive(Clone, Encodable, Decodable, Debug)]
+pub struct ConstItem {
+    pub defaultness: Defaultness,
+    pub ty: P<Ty>,
+    pub expr: Option<P<Expr>>,
+}
+
 #[derive(Clone, Encodable, Decodable, Debug)]
 pub enum ItemKind {
     /// An `extern crate` item, with the optional *original* crate name if the crate was renamed.
@@ -2914,7 +2921,7 @@ pub enum ItemKind {
     /// A constant item (`const`).
     ///
     /// E.g., `const FOO: i32 = 42;`.
-    Const(Defaultness, P<Ty>, Option<P<Expr>>),
+    Const(ConstItem),
     /// A function declaration (`fn`).
     ///
     /// E.g., `fn foo(bar: usize) -> usize { .. }`.
@@ -3030,7 +3037,7 @@ pub type AssocItem = Item<AssocItemKind>;
 pub enum AssocItemKind {
     /// An associated constant, `const $ident: $ty $def?;` where `def ::= "=" $expr? ;`.
     /// If `def` is parsed, then the constant is provided, and otherwise required.
-    Const(Defaultness, P<Ty>, Option<P<Expr>>),
+    Const(ConstItem),
     /// An associated function.
     Fn(Box<Fn>),
     /// An associated type.
@@ -3042,7 +3049,7 @@ pub enum AssocItemKind {
 impl AssocItemKind {
     pub fn defaultness(&self) -> Defaultness {
         match *self {
-            Self::Const(defaultness, ..)
+            Self::Const(ConstItem { defaultness, .. })
             | Self::Fn(box Fn { defaultness, .. })
             | Self::Type(box TyAlias { defaultness, .. }) => defaultness,
             Self::MacCall(..) => Defaultness::Final,
@@ -3053,7 +3060,7 @@ impl AssocItemKind {
 impl From<AssocItemKind> for ItemKind {
     fn from(assoc_item_kind: AssocItemKind) -> ItemKind {
         match assoc_item_kind {
-            AssocItemKind::Const(a, b, c) => ItemKind::Const(a, b, c),
+            AssocItemKind::Const(item) => ItemKind::Const(item),
             AssocItemKind::Fn(fn_kind) => ItemKind::Fn(fn_kind),
             AssocItemKind::Type(ty_alias_kind) => ItemKind::TyAlias(ty_alias_kind),
             AssocItemKind::MacCall(a) => ItemKind::MacCall(a),
@@ -3066,7 +3073,7 @@ impl TryFrom<ItemKind> for AssocItemKind {
 
     fn try_from(item_kind: ItemKind) -> Result<AssocItemKind, ItemKind> {
         Ok(match item_kind {
-            ItemKind::Const(a, b, c) => AssocItemKind::Const(a, b, c),
+            ItemKind::Const(item) => AssocItemKind::Const(item),
             ItemKind::Fn(fn_kind) => AssocItemKind::Fn(fn_kind),
             ItemKind::TyAlias(ty_kind) => AssocItemKind::Type(ty_kind),
             ItemKind::MacCall(a) => AssocItemKind::MacCall(a),

compiler/rustc_ast/src/mut_visit.rs

@@ -1034,10 +1034,8 @@ pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
             vis.visit_ty(ty);
             visit_opt(expr, |expr| vis.visit_expr(expr));
         }
-        ItemKind::Const(defaultness, ty, expr) => {
-            visit_defaultness(defaultness, vis);
-            vis.visit_ty(ty);
-            visit_opt(expr, |expr| vis.visit_expr(expr));
+        ItemKind::Const(item) => {
+            visit_const_item(item, vis);
         }
         ItemKind::Fn(box Fn { defaultness, generics, sig, body }) => {
             visit_defaultness(defaultness, vis);
@@ -1120,10 +1118,8 @@ pub fn noop_flat_map_assoc_item<T: MutVisitor>(
     visitor.visit_vis(vis);
     visit_attrs(attrs, visitor);
     match kind {
-        AssocItemKind::Const(defaultness, ty, expr) => {
-            visit_defaultness(defaultness, visitor);
-            visitor.visit_ty(ty);
-            visit_opt(expr, |expr| visitor.visit_expr(expr));
+        AssocItemKind::Const(item) => {
+            visit_const_item(item, visitor);
         }
         AssocItemKind::Fn(box Fn { defaultness, generics, sig, body }) => {
             visit_defaultness(defaultness, visitor);
@@ -1153,6 +1149,15 @@ pub fn noop_flat_map_assoc_item<T: MutVisitor>(
     smallvec![item]
 }
 
+fn visit_const_item<T: MutVisitor>(
+    ConstItem { defaultness, ty, expr }: &mut ConstItem,
+    visitor: &mut T,
+) {
+    visit_defaultness(defaultness, visitor);
+    visitor.visit_ty(ty);
+    visit_opt(expr, |expr| visitor.visit_expr(expr));
+}
+
 pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
     let FnHeader { unsafety, asyncness, constness, ext: _ } = header;
     visit_constness(constness, vis);

compiler/rustc_ast/src/visit.rs

@@ -305,9 +305,9 @@ pub fn walk_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a Item) {
     match &item.kind {
         ItemKind::ExternCrate(_) => {}
         ItemKind::Use(use_tree) => visitor.visit_use_tree(use_tree, item.id, false),
-        ItemKind::Static(Static { ty: typ, mutability: _, expr })
-        | ItemKind::Const(_, typ, expr) => {
-            visitor.visit_ty(typ);
+        ItemKind::Static(Static { ty, mutability: _, expr })
+        | ItemKind::Const(ConstItem { ty, expr, .. }) => {
+            visitor.visit_ty(ty);
             walk_list!(visitor, visit_expr, expr);
         }
         ItemKind::Fn(box Fn { defaultness: _, generics, sig, body }) => {
@@ -675,7 +675,7 @@ pub fn walk_assoc_item<'a, V: Visitor<'a>>(visitor: &mut V, item: &'a AssocItem,
     visitor.visit_ident(ident);
     walk_list!(visitor, visit_attribute, attrs);
     match kind {
-        AssocItemKind::Const(_, ty, expr) => {
+        AssocItemKind::Const(ConstItem { ty, expr, .. }) => {
             visitor.visit_ty(ty);
             walk_list!(visitor, visit_expr, expr);
         }