Allocate inside lower_path_extra.

src/librustc/hir/lowering.rs

@@ -1800,8 +1800,8 @@ fn lower_path_extra(
         p: &Path,
         param_mode: ParamMode,
         explicit_owner: Option<NodeId>,
-    ) -> hir::Path<'hir> {
-        hir::Path {
+    ) -> &'hir hir::Path<'hir> {
+        self.arena.alloc(hir::Path {
             res,
             segments: self.arena.alloc_from_iter(p.segments.iter().map(|segment| {
                 self.lower_path_segment(
@@ -1815,10 +1815,10 @@ fn lower_path_extra(
                 )
             })),
             span: p.span,
-        }
+        })
     }
 
-    fn lower_path(&mut self, id: NodeId, p: &Path, param_mode: ParamMode) -> hir::Path<'hir> {
+    fn lower_path(&mut self, id: NodeId, p: &Path, param_mode: ParamMode) -> &'hir hir::Path<'hir> {
         let res = self.expect_full_res(id);
         let res = self.lower_res(res);
         self.lower_path_extra(res, p, param_mode, None)
@@ -2396,12 +2396,8 @@ fn lower_async_fn_output_type_to_future_bound(
         });
 
         // ::std::future::Future<future_params>
-        let future_path = self.arena.alloc(self.std_path(
-            span,
-            &[sym::future, sym::Future],
-            Some(future_params),
-            false,
-        ));
+        let future_path =
+            self.std_path(span, &[sym::future, sym::Future], Some(future_params), false);
 
         hir::GenericBound::Trait(
             hir::PolyTraitRef {
@@ -3048,7 +3044,7 @@ fn pat_std_enum(
         subpats: &'hir [&'hir hir::Pat<'hir>],
     ) -> &'hir hir::Pat<'hir> {
         let path = self.std_path(span, components, None, true);
-        let qpath = hir::QPath::Resolved(None, self.arena.alloc(path));
+        let qpath = hir::QPath::Resolved(None, path);
         let pt = if subpats.is_empty() {
             hir::PatKind::Path(qpath)
         } else {
@@ -3096,7 +3092,7 @@ fn std_path(
         components: &[Symbol],
         params: Option<&'hir hir::GenericArgs<'hir>>,
         is_value: bool,
-    ) -> hir::Path<'hir> {
+    ) -> &'hir hir::Path<'hir> {
         let ns = if is_value { Namespace::ValueNS } else { Namespace::TypeNS };
         let (path, res) = self.resolver.resolve_str_path(span, self.crate_root, components, ns);
 
@@ -3116,11 +3112,11 @@ fn std_path(
             .collect();
         segments.last_mut().unwrap().args = params;
 
-        hir::Path {
+        self.arena.alloc(hir::Path {
             span,
             res: res.map_id(|_| panic!("unexpected `NodeId`")),
             segments: self.arena.alloc_from_iter(segments),
-        }
+        })
     }
 
     fn ty_path(

src/librustc/hir/lowering/expr.rs

@@ -827,7 +827,7 @@ fn lower_expr_range(
         let is_unit = fields.is_empty();
         let struct_path = [sym::ops, path];
         let struct_path = self.std_path(span, &struct_path, None, is_unit);
-        let struct_path = hir::QPath::Resolved(None, self.arena.alloc(struct_path));
+        let struct_path = hir::QPath::Resolved(None, struct_path);
 
         if is_unit {
             hir::ExprKind::Path(struct_path)
@@ -1336,7 +1336,7 @@ fn expr_call_std_assoc_fn(
         assoc_fn_name: &str,
         args: &'hir [hir::Expr<'hir>],
     ) -> hir::ExprKind<'hir> {
-        let ty_path = self.arena.alloc(self.std_path(span, ty_path_components, None, false));
+        let ty_path = self.std_path(span, ty_path_components, None, false);
         let ty =
             self.arena.alloc(self.ty_path(ty_path_id, span, hir::QPath::Resolved(None, ty_path)));
         let fn_seg = self.arena.alloc(hir::PathSegment::from_ident(Ident::from_str(assoc_fn_name)));
@@ -1354,11 +1354,7 @@ fn expr_std_path(
         attrs: AttrVec,
     ) -> hir::Expr<'hir> {
         let path = self.std_path(span, components, params, true);
-        self.expr(
-            span,
-            hir::ExprKind::Path(hir::QPath::Resolved(None, self.arena.alloc(path))),
-            attrs,
-        )
+        self.expr(span, hir::ExprKind::Path(hir::QPath::Resolved(None, path)), attrs)
     }
 
     pub(super) fn expr_ident(

src/librustc/hir/lowering/item.rs

@@ -507,7 +507,7 @@ fn lower_use_tree(
                         let new_id = this.lower_node_id(new_node_id);
                         let res = this.lower_res(res);
                         let path = this.lower_path_extra(res, &path, ParamMode::Explicit, None);
-                        let kind = hir::ItemKind::Use(this.arena.alloc(path), hir::UseKind::Single);
+                        let kind = hir::ItemKind::Use(path, hir::UseKind::Single);
                         let vis = this.rebuild_vis(&vis);
 
                         this.insert_item(hir::Item {
@@ -522,15 +522,11 @@ fn lower_use_tree(
                 }
 
                 let path = self.lower_path_extra(ret_res, &path, ParamMode::Explicit, None);
-                let path = self.arena.alloc(path);
                 hir::ItemKind::Use(path, hir::UseKind::Single)
             }
             UseTreeKind::Glob => {
-                let path = self.arena.alloc(self.lower_path(
-                    id,
-                    &Path { segments, span: path.span },
-                    ParamMode::Explicit,
-                ));
+                let path =
+                    self.lower_path(id, &Path { segments, span: path.span }, ParamMode::Explicit);
                 hir::ItemKind::Use(path, hir::UseKind::Glob)
             }
             UseTreeKind::Nested(ref trees) => {
@@ -618,7 +614,6 @@ fn lower_use_tree(
                 let res = self.expect_full_res_from_use(id).next().unwrap_or(Res::Err);
                 let res = self.lower_res(res);
                 let path = self.lower_path_extra(res, &prefix, ParamMode::Explicit, None);
-                let path = self.arena.alloc(path);
                 hir::ItemKind::Use(path, hir::UseKind::ListStem)
             }
         }
@@ -627,7 +622,7 @@ fn lower_use_tree(
     /// Paths like the visibility path in `pub(super) use foo::{bar, baz}` are repeated
     /// many times in the HIR tree; for each occurrence, we need to assign distinct
     /// `NodeId`s. (See, e.g., #56128.)
-    fn rebuild_use_path(&mut self, path: &hir::Path<'hir>) -> hir::Path<'hir> {
+    fn rebuild_use_path(&mut self, path: &hir::Path<'hir>) -> &'hir hir::Path<'hir> {
         debug!("rebuild_use_path(path = {:?})", path);
         let segments =
             self.arena.alloc_from_iter(path.segments.iter().map(|seg| hir::PathSegment {
@@ -637,7 +632,7 @@ fn rebuild_use_path(&mut self, path: &hir::Path<'hir>) -> hir::Path<'hir> {
                 args: None,
                 infer_args: seg.infer_args,
             }));
-        hir::Path { span: path.span, res: path.res, segments }
+        self.arena.alloc(hir::Path { span: path.span, res: path.res, segments })
     }
 
     fn rebuild_vis(&mut self, vis: &hir::Visibility<'hir>) -> hir::Visibility<'hir> {
@@ -647,7 +642,7 @@ fn rebuild_vis(&mut self, vis: &hir::Visibility<'hir>) -> hir::Visibility<'hir>
             hir::VisibilityKind::Inherited => hir::VisibilityKind::Inherited,
             hir::VisibilityKind::Restricted { ref path, hir_id: _ } => {
                 hir::VisibilityKind::Restricted {
-                    path: self.arena.alloc(self.rebuild_use_path(path)),
+                    path: self.rebuild_use_path(path),
                     hir_id: self.next_id(),
                 }
             }
@@ -944,12 +939,7 @@ fn lower_visibility(
                 let res = self.expect_full_res(id);
                 let res = self.lower_res(res);
                 hir::VisibilityKind::Restricted {
-                    path: self.arena.alloc(self.lower_path_extra(
-                        res,
-                        path,
-                        ParamMode::Explicit,
-                        explicit_owner,
-                    )),
+                    path: self.lower_path_extra(res, path, ParamMode::Explicit, explicit_owner),
                     hir_id: lowered_id,
                 }
             }