From 6bd534dbdb48f14a761356e22573904e5d419706 Mon Sep 17 00:00:00 2001
From: lcnr <rust@lcnr.de>
Date: Fri, 19 Nov 2021 22:18:28 +0100
Subject: [PATCH] return the correct type for closures in `type_of`

---
 compiler/rustc_typeck/src/collect.rs          | 4 +++-
 compiler/rustc_typeck/src/collect/type_of.rs  | 9 +--------
 compiler/rustc_typeck/src/expr_use_visitor.rs | 9 +++++----
 3 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/compiler/rustc_typeck/src/collect.rs b/compiler/rustc_typeck/src/collect.rs
index 209690ec5fc9a..769febfe8cf99 100644
--- a/compiler/rustc_typeck/src/collect.rs
+++ b/compiler/rustc_typeck/src/collect.rs
@@ -294,7 +294,9 @@ impl Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
         if let hir::ExprKind::Closure(..) = expr.kind {
             let def_id = self.tcx.hir().local_def_id(expr.hir_id);
             self.tcx.ensure().generics_of(def_id);
-            self.tcx.ensure().type_of(def_id);
+            // We do not call `type_of` for closures here as that
+            // depends on typecheck and would therefore hide
+            // any further errors in case one typeck fails.
         }
         intravisit::walk_expr(self, expr);
     }
diff --git a/compiler/rustc_typeck/src/collect/type_of.rs b/compiler/rustc_typeck/src/collect/type_of.rs
index 04a68250ced0c..202d811170633 100644
--- a/compiler/rustc_typeck/src/collect/type_of.rs
+++ b/compiler/rustc_typeck/src/collect/type_of.rs
@@ -463,14 +463,7 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
 
         Node::Field(field) => icx.to_ty(field.ty),
 
-        Node::Expr(&Expr { kind: ExprKind::Closure(.., gen), .. }) => {
-            let substs = InternalSubsts::identity_for_item(tcx, def_id.to_def_id());
-            if let Some(movability) = gen {
-                tcx.mk_generator(def_id.to_def_id(), substs, movability)
-            } else {
-                tcx.mk_closure(def_id.to_def_id(), substs)
-            }
-        }
+        Node::Expr(&Expr { kind: ExprKind::Closure(..), .. }) => tcx.typeck(def_id).node_type(hir_id),
 
         Node::AnonConst(_) if let Some(param) = tcx.opt_const_param_of(def_id) => {
             // We defer to `type_of` of the corresponding parameter
diff --git a/compiler/rustc_typeck/src/expr_use_visitor.rs b/compiler/rustc_typeck/src/expr_use_visitor.rs
index 7d0600b99e36e..e57045b20ce59 100644
--- a/compiler/rustc_typeck/src/expr_use_visitor.rs
+++ b/compiler/rustc_typeck/src/expr_use_visitor.rs
@@ -715,13 +715,14 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
 
         debug!("walk_captures({:?})", closure_expr);
 
-        let closure_def_id = self.tcx().hir().local_def_id(closure_expr.hir_id).to_def_id();
-        let upvars = self.tcx().upvars_mentioned(self.body_owner);
+        let tcx = self.tcx();
+        let closure_def_id = tcx.hir().local_def_id(closure_expr.hir_id).to_def_id();
+        let upvars = tcx.upvars_mentioned(self.body_owner);
 
         // For purposes of this function, generator and closures are equivalent.
         let body_owner_is_closure = matches!(
-            self.tcx().type_of(self.body_owner.to_def_id()).kind(),
-            ty::Closure(..) | ty::Generator(..)
+            tcx.hir().body_owner_kind(tcx.hir().local_def_id_to_hir_id(self.body_owner)),
+            hir::BodyOwnerKind::Closure,
         );
 
         // If we have a nested closure, we want to include the fake reads present in the nested closure.