Auto merge of #124401 - oli-obk:some_hir_cleanups, r=cjgillot

Some hir cleanups

It seemed odd to not put `AnonConst` in the arena, compared with the other types that we did put into an arena. This way we can also give it a `Span` without growing a lot of other HIR data structures because of the extra field.

r? compiler

Author: bors

compiler/rustc_ast_lowering/src/index.rs

@@ -62,7 +62,7 @@ pub(super) fn index_hir<'hir>(
         if let Node::Err(span) = node.node {
             let hir_id = HirId { owner: item.def_id(), local_id };
             let msg = format!("ID {hir_id} not encountered when visiting item HIR");
-            tcx.dcx().span_delayed_bug(*span, msg);
+            tcx.dcx().span_delayed_bug(span, msg);
         }
     }
 
@@ -376,7 +376,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
         }
     }
 
-    fn visit_array_length(&mut self, len: &'hir ArrayLen) {
+    fn visit_array_length(&mut self, len: &'hir ArrayLen<'hir>) {
         match len {
             ArrayLen::Infer(inf) => self.insert(inf.span, inf.hir_id, Node::ArrayLenInfer(inf)),
             ArrayLen::Body(..) => intravisit::walk_array_len(self, len),

compiler/rustc_ast_lowering/src/item.rs

@@ -1589,11 +1589,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
                             }),
                         )),
                     )),
-                    default: Some(hir::AnonConst {
+                    default: Some(self.arena.alloc(hir::AnonConst {
                         def_id: anon_const,
                         hir_id: const_id,
                         body: const_body,
-                    }),
+                        span,
+                    })),
                     is_host_effect: true,
                 },
                 colon_span: None,

compiler/rustc_ast_lowering/src/lib.rs

@@ -1178,14 +1178,17 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                                     tokens: None,
                                 };
 
-                                let ct = self.with_new_scopes(span, |this| hir::AnonConst {
-                                    def_id,
-                                    hir_id: this.lower_node_id(node_id),
-                                    body: this.lower_const_body(path_expr.span, Some(&path_expr)),
+                                let ct = self.with_new_scopes(span, |this| {
+                                    self.arena.alloc(hir::AnonConst {
+                                        def_id,
+                                        hir_id: this.lower_node_id(node_id),
+                                        body: this
+                                            .lower_const_body(path_expr.span, Some(&path_expr)),
+                                        span,
+                                    })
                                 });
                                 return GenericArg::Const(ConstArg {
                                     value: ct,
-                                    span,
                                     is_desugared_from_effects: false,
                                 });
                             }
@@ -1197,7 +1200,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             }
             ast::GenericArg::Const(ct) => GenericArg::Const(ConstArg {
                 value: self.lower_anon_const(ct),
-                span: self.lower_span(ct.value.span),
                 is_desugared_from_effects: false,
             }),
         }
@@ -2315,7 +2317,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     }
 
     #[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
-    fn lower_array_length(&mut self, c: &AnonConst) -> hir::ArrayLen {
+    fn lower_array_length(&mut self, c: &AnonConst) -> hir::ArrayLen<'hir> {
         match c.value.kind {
             ExprKind::Underscore => {
                 if self.tcx.features().generic_arg_infer {
@@ -2338,12 +2340,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
     }
 
-    fn lower_anon_const(&mut self, c: &AnonConst) -> hir::AnonConst {
-        self.with_new_scopes(c.value.span, |this| hir::AnonConst {
+    fn lower_anon_const(&mut self, c: &AnonConst) -> &'hir hir::AnonConst {
+        self.arena.alloc(self.with_new_scopes(c.value.span, |this| hir::AnonConst {
             def_id: this.local_def_id(c.id),
             hir_id: this.lower_node_id(c.id),
             body: this.lower_const_body(c.value.span, Some(&c.value)),
-        })
+            span: this.lower_span(c.value.span),
+        }))
     }
 
     fn lower_unsafe_source(&mut self, u: UnsafeSource) -> hir::UnsafeSource {
@@ -2650,8 +2653,7 @@ impl<'hir> GenericArgsCtor<'hir> {
 
         lcx.children.push((def_id, hir::MaybeOwner::NonOwner(hir_id)));
         self.args.push(hir::GenericArg::Const(hir::ConstArg {
-            value: hir::AnonConst { def_id, hir_id, body },
-            span,
+            value: lcx.arena.alloc(hir::AnonConst { def_id, hir_id, body, span }),
             is_desugared_from_effects: true,
         }))
     }

compiler/rustc_hir/src/hir.rs

@@ -229,9 +229,8 @@ impl<'hir> PathSegment<'hir> {
 }
 
 #[derive(Clone, Copy, Debug, HashStable_Generic)]
-pub struct ConstArg {
-    pub value: AnonConst,
-    pub span: Span,
+pub struct ConstArg<'hir> {
+    pub value: &'hir AnonConst,
     /// Indicates whether this comes from a `~const` desugaring.
     pub is_desugared_from_effects: bool,
 }
@@ -252,7 +251,7 @@ impl InferArg {
 pub enum GenericArg<'hir> {
     Lifetime(&'hir Lifetime),
     Type(&'hir Ty<'hir>),
-    Const(ConstArg),
+    Const(ConstArg<'hir>),
     Infer(InferArg),
 }
 
@@ -261,7 +260,7 @@ impl GenericArg<'_> {
         match self {
             GenericArg::Lifetime(l) => l.ident.span,
             GenericArg::Type(t) => t.span,
-            GenericArg::Const(c) => c.span,
+            GenericArg::Const(c) => c.value.span,
             GenericArg::Infer(i) => i.span,
         }
     }
@@ -490,7 +489,7 @@ pub enum GenericParamKind<'hir> {
     Const {
         ty: &'hir Ty<'hir>,
         /// Optional default value for the const generic param
-        default: Option<AnonConst>,
+        default: Option<&'hir AnonConst>,
         is_host_effect: bool,
     },
 }
@@ -1562,12 +1561,12 @@ impl fmt::Display for ConstContext {
 pub type Lit = Spanned<LitKind>;
 
 #[derive(Copy, Clone, Debug, HashStable_Generic)]
-pub enum ArrayLen {
+pub enum ArrayLen<'hir> {
     Infer(InferArg),
-    Body(AnonConst),
+    Body(&'hir AnonConst),
 }
 
-impl ArrayLen {
+impl ArrayLen<'_> {
     pub fn hir_id(&self) -> HirId {
         match self {
             ArrayLen::Infer(InferArg { hir_id, .. }) | ArrayLen::Body(AnonConst { hir_id, .. }) => {
@@ -1590,6 +1589,7 @@ pub struct AnonConst {
     pub hir_id: HirId,
     pub def_id: LocalDefId,
     pub body: BodyId,
+    pub span: Span,
 }
 
 /// An inline constant expression `const { something }`.
@@ -2002,7 +2002,7 @@ pub enum ExprKind<'hir> {
     ///
     /// E.g., `[1; 5]`. The first expression is the element
     /// to be repeated; the second is the number of times to repeat it.
-    Repeat(&'hir Expr<'hir>, ArrayLen),
+    Repeat(&'hir Expr<'hir>, ArrayLen<'hir>),
 
     /// A suspension point for coroutines (i.e., `yield <expr>`).
     Yield(&'hir Expr<'hir>, YieldSource),
@@ -2382,7 +2382,7 @@ pub struct TypeBinding<'hir> {
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub enum Term<'hir> {
     Ty(&'hir Ty<'hir>),
-    Const(AnonConst),
+    Const(&'hir AnonConst),
 }
 
 impl<'hir> From<&'hir Ty<'hir>> for Term<'hir> {
@@ -2391,8 +2391,8 @@ impl<'hir> From<&'hir Ty<'hir>> for Term<'hir> {
     }
 }
 
-impl<'hir> From<AnonConst> for Term<'hir> {
-    fn from(c: AnonConst) -> Self {
+impl<'hir> From<&'hir AnonConst> for Term<'hir> {
+    fn from(c: &'hir AnonConst) -> Self {
         Term::Const(c)
     }
 }
@@ -2683,7 +2683,7 @@ pub enum TyKind<'hir> {
     /// A variable length slice (i.e., `[T]`).
     Slice(&'hir Ty<'hir>),
     /// A fixed length array (i.e., `[T; n]`).
-    Array(&'hir Ty<'hir>, ArrayLen),
+    Array(&'hir Ty<'hir>, ArrayLen<'hir>),
     /// A raw pointer (i.e., `*const T` or `*mut T`).
     Ptr(MutTy<'hir>),
     /// A reference (i.e., `&'a T` or `&'a mut T`).
@@ -2712,7 +2712,7 @@ pub enum TyKind<'hir> {
     /// where `Bound` is a trait or a lifetime.
     TraitObject(&'hir [PolyTraitRef<'hir>], &'hir Lifetime, TraitObjectSyntax),
     /// Unused for now.
-    Typeof(AnonConst),
+    Typeof(&'hir AnonConst),
     /// `TyKind::Infer` means the type should be inferred instead of it having been
     /// specified. This can appear anywhere in a type.
     Infer,
@@ -2745,10 +2745,10 @@ pub enum InlineAsmOperand<'hir> {
         out_expr: Option<&'hir Expr<'hir>>,
     },
     Const {
-        anon_const: AnonConst,
+        anon_const: &'hir AnonConst,
     },
     SymFn {
-        anon_const: AnonConst,
+        anon_const: &'hir AnonConst,
     },
     SymStatic {
         path: QPath<'hir>,
@@ -2950,7 +2950,7 @@ pub struct Variant<'hir> {
     /// Fields and constructor id of the variant.
     pub data: VariantData<'hir>,
     /// Explicit discriminant (e.g., `Foo = 1`).
-    pub disr_expr: Option<AnonConst>,
+    pub disr_expr: Option<&'hir AnonConst>,
     /// Span
     pub span: Span,
 }
@@ -3479,15 +3479,13 @@ impl<'hir> OwnerNode<'hir> {
         }
     }
 
-    // Span by reference to pass to `Node::Err`.
-    #[allow(rustc::pass_by_value)]
-    pub fn span(&self) -> &'hir Span {
+    pub fn span(&self) -> Span {
         match self {
             OwnerNode::Item(Item { span, .. })
             | OwnerNode::ForeignItem(ForeignItem { span, .. })
             | OwnerNode::ImplItem(ImplItem { span, .. })
-            | OwnerNode::TraitItem(TraitItem { span, .. }) => span,
-            OwnerNode::Crate(Mod { spans: ModSpans { inner_span, .. }, .. }) => inner_span,
+            | OwnerNode::TraitItem(TraitItem { span, .. }) => *span,
+            OwnerNode::Crate(Mod { spans: ModSpans { inner_span, .. }, .. }) => *inner_span,
             OwnerNode::Synthetic => unreachable!(),
         }
     }
@@ -3632,9 +3630,7 @@ pub enum Node<'hir> {
     PreciseCapturingNonLifetimeArg(&'hir PreciseCapturingNonLifetimeArg),
     // Created by query feeding
     Synthetic,
-    // Span by reference to minimize `Node`'s size
-    #[allow(rustc::pass_by_value)]
-    Err(&'hir Span),
+    Err(Span),
 }
 
 impl<'hir> Node<'hir> {
@@ -3871,7 +3867,7 @@ mod size_asserts {
     static_assert_size!(FnDecl<'_>, 40);
     static_assert_size!(ForeignItem<'_>, 72);
     static_assert_size!(ForeignItemKind<'_>, 40);
-    static_assert_size!(GenericArg<'_>, 32);
+    static_assert_size!(GenericArg<'_>, 24);
     static_assert_size!(GenericBound<'_>, 48);
     static_assert_size!(Generics<'_>, 56);
     static_assert_size!(Impl<'_>, 80);

compiler/rustc_hir/src/intravisit.rs

@@ -338,7 +338,7 @@ pub trait Visitor<'v>: Sized {
     fn visit_pat_field(&mut self, f: &'v PatField<'v>) -> Self::Result {
         walk_pat_field(self, f)
     }
-    fn visit_array_length(&mut self, len: &'v ArrayLen) -> Self::Result {
+    fn visit_array_length(&mut self, len: &'v ArrayLen<'v>) -> Self::Result {
         walk_array_len(self, len)
     }
     fn visit_anon_const(&mut self, c: &'v AnonConst) -> Self::Result {
@@ -703,7 +703,7 @@ pub fn walk_pat_field<'v, V: Visitor<'v>>(visitor: &mut V, field: &'v PatField<'
     visitor.visit_pat(field.pat)
 }
 
-pub fn walk_array_len<'v, V: Visitor<'v>>(visitor: &mut V, len: &'v ArrayLen) -> V::Result {
+pub fn walk_array_len<'v, V: Visitor<'v>>(visitor: &mut V, len: &'v ArrayLen<'v>) -> V::Result {
     match len {
         // FIXME: Use `visit_infer` here.
         ArrayLen::Infer(InferArg { hir_id, span: _ }) => visitor.visit_id(*hir_id),

compiler/rustc_hir_analysis/src/collect.rs

@@ -143,7 +143,7 @@ impl<'v> Visitor<'v> for HirPlaceholderCollector {
             _ => {}
         }
     }
-    fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
+    fn visit_array_length(&mut self, length: &'v hir::ArrayLen<'v>) {
         if let hir::ArrayLen::Infer(inf) = length {
             self.0.push(inf.span);
         }

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -24,7 +24,7 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
     let hir_id = tcx.local_def_id_to_hir_id(def_id);
 
     let node = tcx.hir_node(hir_id);
-    let Node::AnonConst(_) = node else {
+    let Node::AnonConst(&AnonConst { span, .. }) = node else {
         span_bug!(
             tcx.def_span(def_id),
             "expected anon const in `anon_const_type_of`, got {node:?}"
@@ -134,7 +134,7 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
                 // I dont think it's possible to reach this but I'm not 100% sure - BoxyUwU
                 return Ty::new_error_with_message(
                     tcx,
-                    tcx.def_span(def_id),
+                    span,
                     "unexpected non-GAT usage of an anon const",
                 );
             }
@@ -152,7 +152,7 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
             let Some(type_dependent_def) = tables.type_dependent_def_id(parent_node_id) else {
                 return Ty::new_error_with_message(
                     tcx,
-                    tcx.def_span(def_id),
+                    span,
                     format!("unable to find type-dependent def for {parent_node_id:?}"),
                 );
             };
@@ -194,15 +194,15 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
                     } else {
                         return Ty::new_error_with_message(
                             tcx,
-                            tcx.def_span(def_id),
+                            span,
                             format!("unable to find const parent for {hir_id} in pat {pat:?}"),
                         );
                     }
                 }
                 _ => {
                     return Ty::new_error_with_message(
                         tcx,
-                        tcx.def_span(def_id),
+                        span,
                         format!("unexpected const parent path {parent_node:?}"),
                     );
                 }
@@ -226,19 +226,15 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
                             .map(|idx| (idx, seg))
                     })
             }) else {
-                return Ty::new_error_with_message(
-                    tcx,
-                    tcx.def_span(def_id),
-                    "no arg matching AnonConst in path",
-                );
+                return Ty::new_error_with_message(tcx, span, "no arg matching AnonConst in path");
             };
 
             let generics = match tcx.res_generics_def_id(segment.res) {
                 Some(def_id) => tcx.generics_of(def_id),
                 None => {
                     return Ty::new_error_with_message(
                         tcx,
-                        tcx.def_span(def_id),
+                        span,
                         format!("unexpected anon const res {:?} in path: {:?}", segment.res, path),
                     );
                 }
@@ -250,7 +246,7 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
         _ => {
             return Ty::new_error_with_message(
                 tcx,
-                tcx.def_span(def_id),
+                span,
                 format!("unexpected const parent in type_of(): {parent_node:?}"),
             );
         }
@@ -278,7 +274,7 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
     } else {
         return Ty::new_error_with_message(
             tcx,
-            tcx.def_span(def_id),
+            span,
             format!("const generic parameter not found in {generics:?} at position {arg_idx:?}"),
         );
     }