Auto merge of #101228 - nnethercote:simplify-hir-PathSegment, r=petrochenkov

Simplify `hir::PathSegment`

r? `@petrochenkov`

compiler/rustc_ast_lowering/src/expr.rs

@@ -1776,12 +1776,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
         binding: hir::HirId,
         attrs: AttrVec,
     ) -> hir::Expr<'hir> {
+        let hir_id = self.next_id();
+        let res = Res::Local(binding);
         let expr_path = hir::ExprKind::Path(hir::QPath::Resolved(
             None,
             self.arena.alloc(hir::Path {
                 span: self.lower_span(span),
-                res: Res::Local(binding),
-                segments: arena_vec![self; hir::PathSegment::from_ident(ident)],
+                res,
+                segments: arena_vec![self; hir::PathSegment::new(ident, hir_id, res)],
             }),
         ));
 

compiler/rustc_ast_lowering/src/index.rs

@@ -246,9 +246,7 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
     }
 
     fn visit_path_segment(&mut self, path_span: Span, path_segment: &'hir PathSegment<'hir>) {
-        if let Some(hir_id) = path_segment.hir_id {
-            self.insert(path_span, hir_id, Node::PathSegment(path_segment));
-        }
+        self.insert(path_span, path_segment.hir_id, Node::PathSegment(path_segment));
         intravisit::walk_path_segment(self, path_span, path_segment);
     }
 

compiler/rustc_ast_lowering/src/item.rs

@@ -1439,10 +1439,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
             GenericParamKind::Const { .. } => None,
             GenericParamKind::Type { .. } => {
                 let def_id = self.local_def_id(id).to_def_id();
+                let hir_id = self.next_id();
+                let res = Res::Def(DefKind::TyParam, def_id);
                 let ty_path = self.arena.alloc(hir::Path {
                     span: param_span,
-                    res: Res::Def(DefKind::TyParam, def_id),
-                    segments: self.arena.alloc_from_iter([hir::PathSegment::from_ident(ident)]),
+                    res,
+                    segments: self
+                        .arena
+                        .alloc_from_iter([hir::PathSegment::new(ident, hir_id, res)]),
                 });
                 let ty_id = self.next_id();
                 let bounded_ty =

compiler/rustc_ast_lowering/src/lib.rs

@@ -1260,14 +1260,17 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 return self.lower_path_ty(t, qself, path, ParamMode::Explicit, itctx);
             }
             TyKind::ImplicitSelf => {
+                let hir_id = self.lower_node_id(t.id);
                 let res = self.expect_full_res(t.id);
                 let res = self.lower_res(res);
                 hir::TyKind::Path(hir::QPath::Resolved(
                     None,
                     self.arena.alloc(hir::Path {
                         res,
-                        segments: arena_vec![self; hir::PathSegment::from_ident(
-                            Ident::with_dummy_span(kw::SelfUpper)
+                        segments: arena_vec![self; hir::PathSegment::new(
+                            Ident::with_dummy_span(kw::SelfUpper),
+                            hir_id,
+                            res
                         )],
                         span: self.lower_span(t.span),
                     }),
@@ -2193,12 +2196,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             hir::PredicateOrigin::ImplTrait,
         );
 
+        let hir_id = self.next_id();
+        let res = Res::Def(DefKind::TyParam, def_id.to_def_id());
         let ty = hir::TyKind::Path(hir::QPath::Resolved(
             None,
             self.arena.alloc(hir::Path {
                 span: self.lower_span(span),
-                res: Res::Def(DefKind::TyParam, def_id.to_def_id()),
-                segments: arena_vec![self; hir::PathSegment::from_ident(self.lower_ident(ident))],
+                res,
+                segments:
+                    arena_vec![self; hir::PathSegment::new(self.lower_ident(ident), hir_id, res)],
             }),
         ));
 

compiler/rustc_ast_lowering/src/pat.rs

@@ -254,14 +254,18 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     lower_sub(self),
                 )
             }
-            Some(res) => hir::PatKind::Path(hir::QPath::Resolved(
-                None,
-                self.arena.alloc(hir::Path {
-                    span: self.lower_span(ident.span),
-                    res: self.lower_res(res),
-                    segments: arena_vec![self; hir::PathSegment::from_ident(self.lower_ident(ident))],
-                }),
-            )),
+            Some(res) => {
+                let hir_id = self.next_id();
+                let res = self.lower_res(res);
+                hir::PatKind::Path(hir::QPath::Resolved(
+                    None,
+                    self.arena.alloc(hir::Path {
+                        span: self.lower_span(ident.span),
+                        res,
+                        segments: arena_vec![self; hir::PathSegment::new(self.lower_ident(ident), hir_id, res)],
+                    }),
+            ))
+            }
         }
     }
 

compiler/rustc_ast_lowering/src/path.rs

@@ -250,16 +250,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
 
         let res = self.expect_full_res(segment.id);
-        let id = self.lower_node_id(segment.id);
+        let hir_id = self.lower_node_id(segment.id);
         debug!(
             "lower_path_segment: ident={:?} original-id={:?} new-id={:?}",
-            segment.ident, segment.id, id,
+            segment.ident, segment.id, hir_id,
         );
 
         hir::PathSegment {
             ident: self.lower_ident(segment.ident),
-            hir_id: Some(id),
-            res: Some(self.lower_res(res)),
+            hir_id,
+            res: self.lower_res(res),
             infer_args,
             args: if generic_args.is_empty() && generic_args.span.is_empty() {
                 None