separate ast item for const block items

GrigorenkoPV · GrigorenkoPV · commit 841f8642466e · 2025-12-10T20:36:23.000+03:00
diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
@@ -3564,6 +3564,7 @@ impl Item {
     pub fn opt_generics(&self) -> Option<&Generics> {
         match &self.kind {
             ItemKind::ExternCrate(..)
+            | ItemKind::ConstBlock(_)
             | ItemKind::Use(_)
             | ItemKind::Mod(..)
             | ItemKind::ForeignMod(_)
@@ -3805,6 +3806,15 @@ impl ConstItemRhs {
     }
 }
 
+#[derive(Clone, Encodable, Decodable, Debug, Walkable)]
+pub struct ConstBlockItem {
+    pub body: Box<Expr>,
+}
+
+impl ConstBlockItem {
+    pub const IDENT: Ident = Ident { name: kw::Underscore, span: DUMMY_SP };
+}
+
 // Adding a new variant? Please update `test_item` in `tests/ui/macros/stringify.rs`.
 #[derive(Clone, Encodable, Decodable, Debug)]
 pub enum ItemKind {
@@ -3824,6 +3834,11 @@ pub enum ItemKind {
     ///
     /// E.g., `const FOO: i32 = 42;`.
     Const(Box<ConstItem>),
+    /// A module-level const block.
+    /// Equivalent to `const _: () = const { ... }`.
+    ///
+    /// E.g., `const { assert!(true) }`.
+    ConstBlock(ConstBlockItem),
     /// A function declaration (`fn`).
     ///
     /// E.g., `fn foo(bar: usize) -> usize { .. }`.
@@ -3900,6 +3915,8 @@ impl ItemKind {
             | ItemKind::MacroDef(ident, _)
             | ItemKind::Delegation(box Delegation { ident, .. }) => Some(ident),
 
+            ItemKind::ConstBlock(_) => Some(ConstBlockItem::IDENT),
+
             ItemKind::Use(_)
             | ItemKind::ForeignMod(_)
             | ItemKind::GlobalAsm(_)
@@ -3913,9 +3930,9 @@ impl ItemKind {
     pub fn article(&self) -> &'static str {
         use ItemKind::*;
         match self {
-            Use(..) | Static(..) | Const(..) | Fn(..) | Mod(..) | GlobalAsm(..) | TyAlias(..)
-            | Struct(..) | Union(..) | Trait(..) | TraitAlias(..) | MacroDef(..)
-            | Delegation(..) | DelegationMac(..) => "a",
+            Use(..) | Static(..) | Const(..) | ConstBlock(..) | Fn(..) | Mod(..)
+            | GlobalAsm(..) | TyAlias(..) | Struct(..) | Union(..) | Trait(..) | TraitAlias(..)
+            | MacroDef(..) | Delegation(..) | DelegationMac(..) => "a",
             ExternCrate(..) | ForeignMod(..) | MacCall(..) | Enum(..) | Impl { .. } => "an",
         }
     }
@@ -3926,6 +3943,7 @@ impl ItemKind {
             ItemKind::Use(..) => "`use` import",
             ItemKind::Static(..) => "static item",
             ItemKind::Const(..) => "constant item",
+            ItemKind::ConstBlock(..) => "const block",
             ItemKind::Fn(..) => "function",
             ItemKind::Mod(..) => "module",
             ItemKind::ForeignMod(..) => "extern block",
@@ -3955,7 +3973,18 @@ impl ItemKind {
             | Self::Trait(box Trait { generics, .. })
             | Self::TraitAlias(box TraitAlias { generics, .. })
             | Self::Impl(Impl { generics, .. }) => Some(generics),
-            _ => None,
+
+            Self::ExternCrate(..)
+            | Self::Use(..)
+            | Self::Static(..)
+            | Self::ConstBlock(..)
+            | Self::Mod(..)
+            | Self::ForeignMod(..)
+            | Self::GlobalAsm(..)
+            | Self::MacCall(..)
+            | Self::MacroDef(..)
+            | Self::Delegation(..)
+            | Self::DelegationMac(..) => None,
         }
     }
 }
diff --git a/compiler/rustc_ast/src/visit.rs b/compiler/rustc_ast/src/visit.rs
@@ -422,6 +422,7 @@ macro_rules! common_visitor_and_walkers {
             ByRef,
             Closure,
             Const,
+            ConstBlockItem,
             ConstItem,
             ConstItemRhs,
             Defaultness,
@@ -819,6 +820,8 @@ macro_rules! common_visitor_and_walkers {
                         visit_visitable!($($mut)? vis, use_tree),
                     ItemKind::Static(item) =>
                         visit_visitable!($($mut)? vis, item),
+                    ItemKind::ConstBlock(item) =>
+                        visit_visitable!($($mut)? vis, item),
                     ItemKind::Const(item) =>
                         visit_visitable!($($mut)? vis, item),
                     ItemKind::Mod(safety, ident, mod_kind) =>
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
@@ -183,8 +183,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 self.lower_define_opaque(hir_id, define_opaque);
                 hir::ItemKind::Static(*m, ident, ty, body_id)
             }
-            ItemKind::Const(box ast::ConstItem {
-                ident, generics, ty, rhs, define_opaque, ..
+            ItemKind::Const(box ConstItem {
+                defaultness: _,
+                ident,
+                generics,
+                ty,
+                rhs,
+                define_opaque,
             }) => {
                 let ident = self.lower_ident(*ident);
                 let (generics, (ty, rhs)) = self.lower_generics(
@@ -201,6 +206,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 self.lower_define_opaque(hir_id, &define_opaque);
                 hir::ItemKind::Const(ident, generics, ty, rhs)
             }
+            ItemKind::ConstBlock(ConstBlockItem { body }) => hir::ItemKind::Const(
+                self.lower_ident(ConstBlockItem::IDENT),
+                hir::Generics::empty(),
+                self.arena.alloc(self.ty_tup(DUMMY_SP, &[])),
+                hir::ConstItemRhs::Body({
+                    let body = self.lower_expr_mut(body);
+                    self.record_body(&[], body)
+                }),
+            ),
             ItemKind::Fn(box Fn {
                 sig: FnSig { decl, header, span: fn_sig_span },
                 ident,
diff --git a/compiler/rustc_ast_pretty/src/pprust/state/item.rs b/compiler/rustc_ast_pretty/src/pprust/state/item.rs
@@ -205,6 +205,9 @@ impl<'a> State<'a> {
                     define_opaque.as_deref(),
                 );
             }
+            ast::ItemKind::ConstBlock(ast::ConstBlockItem { body }) => {
+                self.print_expr(body, FixupContext::default())
+            }
             ast::ItemKind::Const(box ast::ConstItem {
                 defaultness,
                 ident,
diff --git a/compiler/rustc_hir/src/target.rs b/compiler/rustc_hir/src/target.rs
@@ -171,6 +171,7 @@ impl Target {
             ast::ItemKind::Use(..) => Target::Use,
             ast::ItemKind::Static { .. } => Target::Static,
             ast::ItemKind::Const(..) => Target::Const,
+            ast::ItemKind::ConstBlock(..) => Target::Const,
             ast::ItemKind::Fn { .. } => Target::Fn,
             ast::ItemKind::Mod(..) => Target::Mod,
             ast::ItemKind::ForeignMod { .. } => Target::ForeignMod,
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
@@ -273,28 +273,7 @@ impl<'a> Parser<'a> {
         {
             // CONST BLOCK ITEM
             self.psess.gated_spans.gate(sym::const_block_items, self.token.span);
-            let block = self.parse_const_block(DUMMY_SP, false)?;
-            ItemKind::Const(Box::new(ConstItem {
-                defaultness: Defaultness::Final,
-                ident: Ident { name: kw::Underscore, span: DUMMY_SP },
-                generics: Generics {
-                    params: thin_vec![],
-                    where_clause: WhereClause {
-                        has_where_token: false,
-                        predicates: thin_vec![],
-                        span: DUMMY_SP,
-                    },
-                    span: DUMMY_SP,
-                },
-                ty: Box::new(Ty {
-                    id: DUMMY_NODE_ID,
-                    kind: TyKind::Tup(thin_vec![]),
-                    span: DUMMY_SP,
-                    tokens: None,
-                }),
-                rhs: Some(ConstItemRhs::Body(block)),
-                define_opaque: None,
-            }))
+            ItemKind::ConstBlock(ConstBlockItem { body: self.parse_expr()? })
         } else if let Const::Yes(const_span) = self.parse_constness(case) {
             // CONST ITEM
             self.recover_const_mut(const_span);
diff --git a/compiler/rustc_passes/src/input_stats.rs b/compiler/rustc_passes/src/input_stats.rs
@@ -572,6 +572,7 @@ impl<'v> ast_visit::Visitor<'v> for StatCollector<'v> {
                 Use,
                 Static,
                 Const,
+                ConstBlock,
                 Fn,
                 Mod,
                 ForeignMod,
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
@@ -276,7 +276,7 @@ impl<'ast, 'tcx> visit::Visitor<'ast> for LanguageItemCollector<'ast, 'tcx> {
             ast::ItemKind::ExternCrate(..) => Target::ExternCrate,
             ast::ItemKind::Use(_) => Target::Use,
             ast::ItemKind::Static(_) => Target::Static,
-            ast::ItemKind::Const(_) => Target::Const,
+            ast::ItemKind::Const(_) | ast::ItemKind::ConstBlock(_) => Target::Const,
             ast::ItemKind::Fn(_) | ast::ItemKind::Delegation(..) => Target::Fn,
             ast::ItemKind::Mod(..) => Target::Mod,
             ast::ItemKind::ForeignMod(_) => Target::ForeignFn,
diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -960,7 +960,10 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             }
 
             // These items do not add names to modules.
-            ItemKind::Impl { .. } | ItemKind::ForeignMod(..) | ItemKind::GlobalAsm(..) => {}
+            ItemKind::Impl { .. }
+            | ItemKind::ForeignMod(..)
+            | ItemKind::GlobalAsm(..)
+            | ItemKind::ConstBlock(..) => {}
 
             ItemKind::MacroDef(..) | ItemKind::MacCall(_) | ItemKind::DelegationMac(..) => {
                 unreachable!()
diff --git a/compiler/rustc_resolve/src/def_collector.rs b/compiler/rustc_resolve/src/def_collector.rs
@@ -121,7 +121,7 @@ impl<'a, 'ra, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'ra, 'tcx> {
                 mutability: s.mutability,
                 nested: false,
             },
-            ItemKind::Const(..) => DefKind::Const,
+            ItemKind::Const(..) | ItemKind::ConstBlock(..) => DefKind::Const,
             ItemKind::Fn(..) | ItemKind::Delegation(..) => DefKind::Fn,
             ItemKind::MacroDef(ident, def) => {
                 let edition = i.span.edition();
diff --git a/compiler/rustc_resolve/src/effective_visibilities.rs b/compiler/rustc_resolve/src/effective_visibilities.rs
@@ -273,6 +273,7 @@ impl<'a, 'ra, 'tcx> Visitor<'a> for EffectiveVisibilitiesVisitor<'a, 'ra, 'tcx>
             | ast::ItemKind::Use(..)
             | ast::ItemKind::Static(..)
             | ast::ItemKind::Const(..)
+            | ast::ItemKind::ConstBlock(..)
             | ast::ItemKind::GlobalAsm(..)
             | ast::ItemKind::TyAlias(..)
             | ast::ItemKind::TraitAlias(..)
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
@@ -2702,8 +2702,8 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
         debug!("(resolving item) resolving {:?} ({:?})", item.kind.ident(), item.kind);
 
         let def_kind = self.r.local_def_kind(item.id);
-        match item.kind {
-            ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
+        match &item.kind {
+            ItemKind::TyAlias(box TyAlias { generics, .. }) => {
                 self.with_generic_param_rib(
                     &generics.params,
                     RibKind::Item(HasGenericParams::Yes(generics.span), def_kind),
@@ -2714,7 +2714,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 );
             }
 
-            ItemKind::Fn(box Fn { ref generics, ref define_opaque, .. }) => {
+            ItemKind::Fn(box Fn { generics, define_opaque, .. }) => {
                 self.with_generic_param_rib(
                     &generics.params,
                     RibKind::Item(HasGenericParams::Yes(generics.span), def_kind),
@@ -2726,19 +2726,13 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 self.resolve_define_opaques(define_opaque);
             }
 
-            ItemKind::Enum(_, ref generics, _)
-            | ItemKind::Struct(_, ref generics, _)
-            | ItemKind::Union(_, ref generics, _) => {
+            ItemKind::Enum(_, generics, _)
+            | ItemKind::Struct(_, generics, _)
+            | ItemKind::Union(_, generics, _) => {
                 self.resolve_adt(item, generics);
             }
 
-            ItemKind::Impl(Impl {
-                ref generics,
-                ref of_trait,
-                ref self_ty,
-                items: ref impl_items,
-                ..
-            }) => {
+            ItemKind::Impl(Impl { generics, of_trait, self_ty, items: impl_items, .. }) => {
                 self.diag_metadata.current_impl_items = Some(impl_items);
                 self.resolve_implementation(
                     &item.attrs,
@@ -2751,7 +2745,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 self.diag_metadata.current_impl_items = None;
             }
 
-            ItemKind::Trait(box Trait { ref generics, ref bounds, ref items, .. }) => {
+            ItemKind::Trait(box Trait { generics, bounds, items, .. }) => {
                 // Create a new rib for the trait-wide type parameters.
                 self.with_generic_param_rib(
                     &generics.params,
@@ -2770,7 +2764,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 );
             }
 
-            ItemKind::TraitAlias(box TraitAlias { ref generics, ref bounds, .. }) => {
+            ItemKind::TraitAlias(box TraitAlias { generics, bounds, .. }) => {
                 // Create a new rib for the trait-wide type parameters.
                 self.with_generic_param_rib(
                     &generics.params,
@@ -2810,33 +2804,27 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 self.parent_scope.module = orig_module;
             }
 
-            ItemKind::Static(box ast::StaticItem {
-                ident,
-                ref ty,
-                ref expr,
-                ref define_opaque,
-                ..
-            }) => {
+            ItemKind::Static(box ast::StaticItem { ident, ty, expr, define_opaque, .. }) => {
                 self.with_static_rib(def_kind, |this| {
                     this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
                         this.visit_ty(ty);
                     });
                     if let Some(expr) = expr {
                         // We already forbid generic params because of the above item rib,
                         // so it doesn't matter whether this is a trivial constant.
-                        this.resolve_static_body(expr, Some((ident, ConstantItemKind::Static)));
+                        this.resolve_static_body(expr, Some((*ident, ConstantItemKind::Static)));
                     }
                 });
                 self.resolve_define_opaques(define_opaque);
             }
 
             ItemKind::Const(box ast::ConstItem {
                 ident,
-                ref generics,
-                ref ty,
-                ref rhs,
-                ref define_opaque,
-                ..
+                generics,
+                ty,
+                rhs,
+                define_opaque,
+                defaultness: _,
             }) => {
                 self.with_generic_param_rib(
                     &generics.params,
@@ -2862,15 +2850,32 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                         if let Some(rhs) = rhs {
                             this.resolve_const_item_rhs(
                                 rhs,
-                                Some((ident, ConstantItemKind::Const)),
+                                Some((*ident, ConstantItemKind::Const)),
                             );
                         }
                     },
                 );
                 self.resolve_define_opaques(define_opaque);
             }
+            ItemKind::ConstBlock(ConstBlockItem { body }) => self.with_generic_param_rib(
+                &[],
+                RibKind::Item(HasGenericParams::No, def_kind),
+                item.id,
+                LifetimeBinderKind::ConstItem,
+                DUMMY_SP,
+                |this| {
+                    this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Infer), |this| {
+                        this.with_constant_rib(
+                            IsRepeatExpr::No,
+                            ConstantHasGenerics::Yes,
+                            Some((ConstBlockItem::IDENT, ConstantItemKind::Const)),
+                            |this| this.visit_expr(body),
+                        );
+                    })
+                },
+            ),
 
-            ItemKind::Use(ref use_tree) => {
+            ItemKind::Use(use_tree) => {
                 let maybe_exported = match use_tree.kind {
                     UseTreeKind::Simple(_) | UseTreeKind::Glob => MaybeExported::Ok(item.id),
                     UseTreeKind::Nested { .. } => MaybeExported::NestedUse(&item.vis),
@@ -2880,7 +2885,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 self.future_proof_import(use_tree);
             }
 
-            ItemKind::MacroDef(_, ref macro_def) => {
+            ItemKind::MacroDef(_, macro_def) => {
                 // Maintain macro_rules scopes in the same way as during early resolution
                 // for diagnostics and doc links.
                 if macro_def.macro_rules {
@@ -2893,7 +2898,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 visit::walk_item(self, item);
             }
 
-            ItemKind::Delegation(ref delegation) => {
+            ItemKind::Delegation(delegation) => {
                 let span = delegation.path.segments.last().unwrap().ident.span;
                 self.with_generic_param_rib(
                     &[],
@@ -5342,6 +5347,7 @@ impl<'ast> Visitor<'ast> for ItemInfoCollector<'_, '_, '_> {
 
             ItemKind::Mod(..)
             | ItemKind::Static(..)
+            | ItemKind::ConstBlock(..)
             | ItemKind::Use(..)
             | ItemKind::ExternCrate(..)
             | ItemKind::MacroDef(..)
diff --git a/tests/ui/macros/stringify.rs b/tests/ui/macros/stringify.rs
