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) => {
+        ItemKind::Const(item) => {
-            visit_defaultness(defaultness, vis);
+            visit_const_item(item, vis);
-            vis.visit_ty(ty);
-            visit_opt(expr, |expr| vis.visit_expr(expr));
         }
         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) => {
+        AssocItemKind::Const(item) => {
-            visit_defaultness(defaultness, visitor);
+            visit_const_item(item, visitor);
-            visitor.visit_ty(ty);
-            visit_opt(expr, |expr| visitor.visit_expr(expr));
         }
         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::Static(Static { ty, mutability: _, expr })
-        | ItemKind::Const(_, typ, expr) => {
+        | ItemKind::Const(ConstItem { ty, expr, .. }) => {
-            visitor.visit_ty(typ);
+            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);
         }

compiler/rustc_ast_lowering/src/item.rs

@@ -233,8 +233,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let (ty, body_id) = self.lower_const_item(t, span, e.as_deref());
                 hir::ItemKind::Static(ty, *m, body_id)
             }
-            ItemKind::Const(_, t, e) => {
+            ItemKind::Const(ast::ConstItem { ty, expr, .. }) => {
-                let (ty, body_id) = self.lower_const_item(t, span, e.as_deref());
+                let (ty, body_id) = self.lower_const_item(ty, span, expr.as_deref());
                 hir::ItemKind::Const(ty, body_id)
             }
             ItemKind::Fn(box Fn {
@@ -708,10 +708,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let trait_item_def_id = hir_id.expect_owner();
 
         let (generics, kind, has_default) = match &i.kind {
-            AssocItemKind::Const(_, ty, default) => {
+            AssocItemKind::Const(ConstItem { ty, expr, .. }) => {
                 let ty =
                     self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy));
-                let body = default.as_ref().map(|x| self.lower_const_body(i.span, Some(x)));
+                let body = expr.as_ref().map(|x| self.lower_const_body(i.span, Some(x)));
                 (hir::Generics::empty(), hir::TraitItemKind::Const(ty, body), body.is_some())
             }
             AssocItemKind::Fn(box Fn { sig, generics, body: None, .. }) => {
@@ -809,7 +809,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         self.lower_attrs(hir_id, &i.attrs);
 
         let (generics, kind) = match &i.kind {
-            AssocItemKind::Const(_, ty, expr) => {
+            AssocItemKind::Const(ConstItem { ty, expr, .. }) => {
                 let ty =
                     self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy));
                 (

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -983,8 +983,8 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     self.err_handler().emit_err(errors::FieldlessUnion { span: item.span });
                 }
             }
-            ItemKind::Const(def, .., None) => {
+            ItemKind::Const(ConstItem { defaultness, expr: None, .. }) => {
-                self.check_defaultness(item.span, *def);
+                self.check_defaultness(item.span, *defaultness);
                 self.session.emit_err(errors::ConstWithoutBody {
                     span: item.span,
                     replace_span: self.ending_semi_or_hi(item.span),
@@ -1259,13 +1259,11 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
 
         if ctxt == AssocCtxt::Impl {
             match &item.kind {
-                AssocItemKind::Const(_, _, body) => {
+                AssocItemKind::Const(ConstItem { expr: None, .. }) => {
-                    if body.is_none() {
+                    self.session.emit_err(errors::AssocConstWithoutBody {
-                        self.session.emit_err(errors::AssocConstWithoutBody {
+                        span: item.span,
-                            span: item.span,
+                        replace_span: self.ending_semi_or_hi(item.span),
-                            replace_span: self.ending_semi_or_hi(item.span),
+                    });
-                        });
-                    }
                 }
                 AssocItemKind::Fn(box Fn { body, .. }) => {
                     if body.is_none() {

compiler/rustc_ast_pretty/src/pprust/state/item.rs

@@ -168,8 +168,15 @@ impl<'a> State<'a> {
                     def,
                 );
             }
-            ast::ItemKind::Const(def, ty, body) => {
+            ast::ItemKind::Const(ast::ConstItem { defaultness, ty, expr }) => {
-                self.print_item_const(item.ident, None, ty, body.as_deref(), &item.vis, *def);
+                self.print_item_const(
+                    item.ident,
+                    None,
+                    ty,
+                    expr.as_deref(),
+                    &item.vis,
+                    *defaultness,
+                );
             }
             ast::ItemKind::Fn(box ast::Fn { defaultness, sig, generics, body }) => {
                 self.print_fn_full(
@@ -508,8 +515,8 @@ impl<'a> State<'a> {
             ast::AssocItemKind::Fn(box ast::Fn { defaultness, sig, generics, body }) => {
                 self.print_fn_full(sig, ident, generics, vis, *defaultness, body.as_deref(), attrs);
             }
-            ast::AssocItemKind::Const(def, ty, body) => {
+            ast::AssocItemKind::Const(ast::ConstItem { defaultness, ty, expr }) => {
-                self.print_item_const(ident, None, ty, body.as_deref(), vis, *def);
+                self.print_item_const(ident, None, ty, expr.as_deref(), vis, *defaultness);
             }
             ast::AssocItemKind::Type(box ast::TyAlias {
                 defaultness,

compiler/rustc_builtin_macros/src/test.rs

@@ -264,11 +264,11 @@ pub fn expand_test_or_bench(
             cx.attr_name_value_str(sym::rustc_test_marker, test_path_symbol, attr_sp),
         ],
         // const $ident: test::TestDescAndFn =
-        ast::ItemKind::Const(
+        ast::ItemKind::Const(ast::ConstItem {
-            ast::Defaultness::Final,
+            defaultness: ast::Defaultness::Final,
-            cx.ty(sp, ast::TyKind::Path(None, test_path("TestDescAndFn"))),
+            ty: cx.ty(sp, ast::TyKind::Path(None, test_path("TestDescAndFn"))),
             // test::TestDescAndFn {
-            Some(
+            expr: Some(
                 cx.expr_struct(
                     sp,
                     test_path("TestDescAndFn"),
@@ -361,7 +361,7 @@ pub fn expand_test_or_bench(
                     ],
                 ), // }
             ),
-        ),
+        }),
     );
     test_const = test_const.map(|mut tc| {
         tc.vis.kind = ast::VisibilityKind::Public;

compiler/rustc_expand/src/build.rs

@@ -638,8 +638,13 @@ impl<'a> ExtCtxt<'a> {
         ty: P<ast::Ty>,
         expr: P<ast::Expr>,
     ) -> P<ast::Item> {
-        let def = ast::Defaultness::Final;
+        let defaultness = ast::Defaultness::Final;
-        self.item(span, name, AttrVec::new(), ast::ItemKind::Const(def, ty, Some(expr)))
+        self.item(
+            span,
+            name,
+            AttrVec::new(),
+            ast::ItemKind::Const(ast::ConstItem { defaultness, ty, expr: Some(expr) }),
+        )
     }
 
     // Builds `#[name]`.

compiler/rustc_lint/src/unused.rs

@@ -805,7 +805,9 @@ trait UnusedDelimLint {
     fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
         use ast::ItemKind::*;
 
-        if let Const(.., Some(expr)) | Static(ast::Static { expr: Some(expr), .. }) = &item.kind {
+        if let Const(ast::ConstItem { expr: Some(expr), .. })
+        | Static(ast::Static { expr: Some(expr), .. }) = &item.kind
+        {
             self.check_unused_delims_expr(
                 cx,
                 expr,

compiler/rustc_parse/src/parser/item.rs

@@ -237,7 +237,7 @@ impl<'a> Parser<'a> {
             } else {
                 self.recover_const_mut(const_span);
                 let (ident, ty, expr) = self.parse_item_global(None)?;
-                (ident, ItemKind::Const(def_(), ty, expr))
+                (ident, ItemKind::Const(ConstItem { defaultness: def_(), ty, expr }))
             }
         } else if self.check_keyword(kw::Trait) || self.check_auto_or_unsafe_trait_item() {
             // TRAIT ITEM
@@ -863,9 +863,13 @@ impl<'a> Parser<'a> {
                 let kind = match AssocItemKind::try_from(kind) {
                     Ok(kind) => kind,
                     Err(kind) => match kind {
-                        ItemKind::Static(Static { ty: a, mutability: _, expr: b }) => {
+                        ItemKind::Static(Static { ty, mutability: _, expr }) => {
                             self.sess.emit_err(errors::AssociatedStaticItemNotAllowed { span });
-                            AssocItemKind::Const(Defaultness::Final, a, b)
+                            AssocItemKind::Const(ConstItem {
+                                defaultness: Defaultness::Final,
+                                ty,
+                                expr,
+                            })
                         }
                         _ => return self.error_bad_item_kind(span, &kind, "`trait`s or `impl`s"),
                     },
@@ -1115,12 +1119,12 @@ impl<'a> Parser<'a> {
                 let kind = match ForeignItemKind::try_from(kind) {
                     Ok(kind) => kind,
                     Err(kind) => match kind {
-                        ItemKind::Const(_, a, b) => {
+                        ItemKind::Const(ConstItem { ty, expr, .. }) => {
                             self.sess.emit_err(errors::ExternItemCannotBeConst {
                                 ident_span: ident.span,
                                 const_span: span.with_hi(ident.span.lo()),
                             });
-                            ForeignItemKind::Static(a, Mutability::Not, b)
+                            ForeignItemKind::Static(ty, Mutability::Not, expr)
                         }
                         _ => return self.error_bad_item_kind(span, &kind, "`extern` blocks"),
                     },

compiler/rustc_resolve/src/late.rs

@@ -2347,7 +2347,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             }
 
             ItemKind::Static(ast::Static { ref ty, ref expr, .. })
-            | ItemKind::Const(_, ref ty, ref expr) => {
+            | ItemKind::Const(ast::ConstItem { ref ty, ref expr, .. }) => {
                 self.with_static_rib(|this| {
                     this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
                         this.visit_ty(ty);
@@ -2625,11 +2625,11 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
         for item in trait_items {
             self.resolve_doc_links(&item.attrs, MaybeExported::Ok(item.id));
             match &item.kind {
-                AssocItemKind::Const(_, ty, default) => {
+                AssocItemKind::Const(ast::ConstItem { ty, expr, .. }) => {
                     self.visit_ty(ty);
                     // Only impose the restrictions of `ConstRibKind` for an
                     // actual constant expression in a provided default.
-                    if let Some(expr) = default {
+                    if let Some(expr) = expr {
                         // We allow arbitrary const expressions inside of associated consts,
                         // even if they are potentially not const evaluatable.
                         //
@@ -2800,7 +2800,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
         use crate::ResolutionError::*;
         self.resolve_doc_links(&item.attrs, MaybeExported::ImplItem(trait_id.ok_or(&item.vis)));
         match &item.kind {
-            AssocItemKind::Const(_, ty, default) => {
+            AssocItemKind::Const(ast::ConstItem { ty, expr, .. }) => {
                 debug!("resolve_implementation AssocItemKind::Const");
                 // If this is a trait impl, ensure the const
                 // exists in trait
@@ -2815,7 +2815,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 );
 
                 self.visit_ty(ty);
-                if let Some(expr) = default {
+                if let Some(expr) = expr {
                     // We allow arbitrary const expressions inside of associated consts,
                     // even if they are potentially not const evaluatable.
                     //

src/tools/clippy/clippy_lints/src/redundant_static_lifetimes.rs

@@ -1,7 +1,7 @@
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::msrvs::{self, Msrv};
 use clippy_utils::source::snippet;
-use rustc_ast::ast::{Item, ItemKind, Ty, TyKind, Static};
+use rustc_ast::ast::{Item, ItemKind, Ty, TyKind, Static, ConstItem};
 use rustc_errors::Applicability;
 use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
@@ -100,7 +100,7 @@ impl EarlyLintPass for RedundantStaticLifetimes {
         }
 
         if !item.span.from_expansion() {
-            if let ItemKind::Const(_, ref var_type, _) = item.kind {
+            if let ItemKind::Const(ConstItem { ty: ref var_type, .. }) = item.kind {
                 Self::visit_type(var_type, cx, "constants have by default a `'static` lifetime");
                 // Don't check associated consts because `'static` cannot be elided on those (issue
                 // #2438)

src/tools/clippy/clippy_utils/src/ast_utils.rs

@@ -287,7 +287,7 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
         (ExternCrate(l), ExternCrate(r)) => l == r,
         (Use(l), Use(r)) => eq_use_tree(l, r),
         (Static(ast::Static{ ty: lt, mutability: lm, expr: le}), Static(ast::Static { ty: rt, mutability: rm, expr: re})) => lm == rm && eq_ty(lt, rt) && eq_expr_opt(le, re),
-        (Const(ld, lt, le), Const(rd, rt, re)) => eq_defaultness(*ld, *rd) && eq_ty(lt, rt) && eq_expr_opt(le, re),
+        (Const(ast::ConstItem { defaultness: ld, ty: lt, expr: le}), Const(ast::ConstItem { defaultness: rd, ty: rt, expr: re} )) => eq_defaultness(*ld, *rd) && eq_ty(lt, rt) && eq_expr_opt(le, re),
         (
             Fn(box ast::Fn {
                 defaultness: ld,
@@ -451,7 +451,7 @@ pub fn eq_foreign_item_kind(l: &ForeignItemKind, r: &ForeignItemKind) -> bool {
 pub fn eq_assoc_item_kind(l: &AssocItemKind, r: &AssocItemKind) -> bool {
     use AssocItemKind::*;
     match (l, r) {
-        (Const(ld, lt, le), Const(rd, rt, re)) => eq_defaultness(*ld, *rd) && eq_ty(lt, rt) && eq_expr_opt(le, re),
+        (Const(ast::ConstItem { defaultness: ld, ty: lt, expr: le}), Const(ast::ConstItem { defaultness: rd, ty: rt, expr: re})) => eq_defaultness(*ld, *rd) && eq_ty(lt, rt) && eq_expr_opt(le, re),
         (
             Fn(box ast::Fn {
                 defaultness: ld,

src/tools/rustfmt/src/items.rs

@@ -1808,7 +1808,7 @@ impl<'a> StaticParts<'a> {
             ast::ItemKind::Static(ast::Static { ref ty, mutability, ref expr}) => {
                 (None, "static", ty, mutability, expr)
             }
-            ast::ItemKind::Const(defaultness, ref ty, ref expr) => {
+            ast::ItemKind::Const(ast::ConstItem { defaultness, ref ty, ref expr}) => {
                 (Some(defaultness), "const", ty, ast::Mutability::Not, expr)
             }
             _ => unreachable!(),
@@ -1827,8 +1827,8 @@ impl<'a> StaticParts<'a> {
 
     pub(crate) fn from_trait_item(ti: &'a ast::AssocItem) -> Self {
         let (defaultness, ty, expr_opt) = match ti.kind {
-            ast::AssocItemKind::Const(defaultness, ref ty, ref expr_opt) => {
+            ast::AssocItemKind::Const(ast::ConstItem {defaultness, ref ty, ref expr}) => {
-                (defaultness, ty, expr_opt)
+                (defaultness, ty, expr)
             }
             _ => unreachable!(),
         };
@@ -1846,7 +1846,7 @@ impl<'a> StaticParts<'a> {
 
     pub(crate) fn from_impl_item(ii: &'a ast::AssocItem) -> Self {
         let (defaultness, ty, expr) = match ii.kind {
-            ast::AssocItemKind::Const(defaultness, ref ty, ref expr) => (defaultness, ty, expr),
+            ast::AssocItemKind::Const(ast::ConstItem { defaultness, ref ty, ref expr}) => (defaultness, ty, expr),
             _ => unreachable!(),
         };
         StaticParts {