Use parent_iter instead of a find_parent_node loop

Author: eholk

compiler/rustc_middle/src/hir/map/mod.rs

@@ -291,6 +291,9 @@ impl<'hir> Map<'hir> {
         Some(def_kind)
     }
 
+    /// Finds the id of the parent node to this one.
+    ///
+    /// If calling repeatedly and iterating over parents, prefer [`Map::parent_iter`].
     pub fn find_parent_node(self, id: HirId) -> Option<HirId> {
         if id.local_id == ItemLocalId::from_u32(0) {
             Some(self.tcx.hir_owner_parent(id.owner))

compiler/rustc_typeck/src/check/generator_interior.rs

@@ -387,18 +387,6 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
             ty.needs_drop(self.fcx.tcx, self.fcx.param_env)
         };
 
-        let find_parent_expr = |mut hir_id| {
-            let hir = self.fcx.tcx.hir();
-            hir_id = hir.find_parent_node(hir_id)?;
-            loop {
-                if let hir::Node::Expr(_) = self.fcx.tcx.hir().find(hir_id)? {
-                    return Some(hir_id);
-                } else {
-                    hir_id = hir.find_parent_node(hir_id)?;
-                }
-            }
-        };
-
         // Typically, the value produced by an expression is consumed by its parent in some way,
         // so we only have to check if the parent contains a yield (note that the parent may, for
         // example, store the value into a local variable, but then we already consider local
@@ -421,7 +409,13 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
             }) {
             self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id)
         } else {
-            let parent_expr = find_parent_expr(expr.hir_id);
+            let parent_expr = self
+                .fcx
+                .tcx
+                .hir()
+                .parent_iter(expr.hir_id)
+                .find(|(_, node)| matches!(node, hir::Node::Expr(_)))
+                .map(|(id, _)| id);
             debug!("parent_expr: {:?}", parent_expr);
             match parent_expr {
                 Some(parent) => Some(Scope { id: parent.local_id, data: ScopeData::Node }),