Rollup merge of rust-lang#101228 - nnethercote:simplify-hir-PathSegment, r=petrochenkov

Simplify `hir::PathSegment`

r? `@petrochenkov`

Author: Dylan-DPC

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

@@ -1431,10 +1431,14 @@ 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

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -935,10 +935,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                 _,
             ) = hir_map.body(fn_body_id).value.kind
             {
-                let opt_suggestions = path_segment
-                    .hir_id
-                    .map(|path_hir_id| self.infcx.tcx.typeck(path_hir_id.owner))
-                    .and_then(|typeck| typeck.type_dependent_def_id(*hir_id))
+                let opt_suggestions = self
+                    .infcx
+                    .tcx
+                    .typeck(path_segment.hir_id.owner)
+                    .type_dependent_def_id(*hir_id)
                     .and_then(|def_id| self.infcx.tcx.impl_of_method(def_id))
                     .map(|def_id| self.infcx.tcx.associated_items(def_id))
                     .map(|assoc_items| {

compiler/rustc_hir/src/def.rs

@@ -308,6 +308,7 @@ pub enum Res<Id = hir::HirId> {
     ///
     /// **Belongs to the type namespace.**
     PrimTy(hir::PrimTy),
+
     /// The `Self` type, optionally with the [`DefId`] of the trait it belongs to and
     /// optionally with the [`DefId`] of the item introducing the `Self` type alias.
     ///
@@ -355,7 +356,8 @@ pub enum Res<Id = hir::HirId> {
     /// const fn baz<T>() -> usize { 10 }
     /// ```
     /// We do however allow `Self` in repeat expression even if it is generic to not break code
-    /// which already works on stable while causing the `const_evaluatable_unchecked` future compat lint:
+    /// which already works on stable while causing the `const_evaluatable_unchecked` future compat
+    /// lint:
     /// ```
     /// fn foo<T>() {
     ///     let _bar = [1_u8; std::mem::size_of::<*mut T>()];
@@ -370,6 +372,7 @@ pub enum Res<Id = hir::HirId> {
         /// from mentioning generics (i.e. when used in an anonymous constant).
         alias_to: Option<(DefId, bool)>,
     },
+
     /// A tool attribute module; e.g., the `rustfmt` in `#[rustfmt::skip]`.
     ///
     /// **Belongs to the type namespace.**
@@ -383,6 +386,7 @@ pub enum Res<Id = hir::HirId> {
     ///
     /// *See also [`Res::SelfTy`].*
     SelfCtor(DefId),
+
     /// A local variable or function parameter.
     ///
     /// **Belongs to the value namespace.**

compiler/rustc_hir/src/hir.rs

@@ -202,13 +202,8 @@ impl Path<'_> {
 pub struct PathSegment<'hir> {
     /// The identifier portion of this path segment.
     pub ident: Ident,
-    // `id` and `res` are optional. We currently only use these in save-analysis,
-    // any path segments without these will not have save-analysis info and
-    // therefore will not have 'jump to def' in IDEs, but otherwise will not be
-    // affected. (In general, we don't bother to get the defs for synthesized
-    // segments, only for segments which have come from the AST).
-    pub hir_id: Option<HirId>,
-    pub res: Option<Res>,
+    pub hir_id: HirId,
+    pub res: Res,
 
     /// Type/lifetime parameters attached to this path. They come in
     /// two flavors: `Path<A,B,C>` and `Path(A,B) -> C`. Note that
@@ -226,12 +221,12 @@ pub struct PathSegment<'hir> {
 
 impl<'hir> PathSegment<'hir> {
     /// Converts an identifier to the corresponding segment.
-    pub fn from_ident(ident: Ident) -> PathSegment<'hir> {
-        PathSegment { ident, hir_id: None, res: None, infer_args: true, args: None }
+    pub fn new(ident: Ident, hir_id: HirId, res: Res) -> PathSegment<'hir> {
+        PathSegment { ident, hir_id, res, infer_args: true, args: None }
     }
 
     pub fn invalid() -> Self {
-        Self::from_ident(Ident::empty())
+        Self::new(Ident::empty(), HirId::INVALID, Res::Err)
     }
 
     pub fn args(&self) -> &GenericArgs<'hir> {

compiler/rustc_hir/src/hir_id.rs

@@ -20,6 +20,9 @@ pub struct HirId {
 }
 
 impl HirId {
+    /// Signal local id which should never be used.
+    pub const INVALID: HirId = HirId { owner: CRATE_DEF_ID, local_id: ItemLocalId::INVALID };
+
     #[inline]
     pub fn expect_owner(self) -> LocalDefId {
         assert_eq!(self.local_id.index(), 0);