1 files changed, 37 insertions, 6 deletions
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 431fa30ed0f..384d08f8348 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -388,9 +388,19 @@ impl<'tcx> ClosureSubsts<'tcx> {
         self.split().parent_substs
     }
 
+    /// Returns an iterator over the list of types of captured paths by the closure.
+    /// In case there was a type error in figuring out the types of the captured path, an
+    /// empty iterator is returned.
     #[inline]
     pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
-        self.tupled_upvars_ty().tuple_fields()
+        match self.tupled_upvars_ty().kind() {
+            TyKind::Error(_) => None,
+            TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
+            TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
+            ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
+        }
+        .into_iter()
+        .flatten()
     }
 
     /// Returns the tuple type representing the upvars for this closure.
@@ -515,9 +525,19 @@ impl<'tcx> GeneratorSubsts<'tcx> {
         self.split().witness.expect_ty()
     }
 
+    /// Returns an iterator over the list of types of captured paths by the generator.
+    /// In case there was a type error in figuring out the types of the captured path, an
+    /// empty iterator is returned.
     #[inline]
     pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
-        self.tupled_upvars_ty().tuple_fields()
+        match self.tupled_upvars_ty().kind() {
+            TyKind::Error(_) => None,
+            TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
+            TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
+            ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
+        }
+        .into_iter()
+        .flatten()
     }
 
     /// Returns the tuple type representing the upvars for this generator.
@@ -660,13 +680,24 @@ pub enum UpvarSubsts<'tcx> {
 }
 
 impl<'tcx> UpvarSubsts<'tcx> {
+    /// Returns an iterator over the list of types of captured paths by the closure/generator.
+    /// In case there was a type error in figuring out the types of the captured path, an
+    /// empty iterator is returned.
     #[inline]
     pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
-        let tupled_upvars_ty = match self {
-            UpvarSubsts::Closure(substs) => substs.as_closure().split().tupled_upvars_ty,
-            UpvarSubsts::Generator(substs) => substs.as_generator().split().tupled_upvars_ty,
+        let tupled_tys = match self {
+            UpvarSubsts::Closure(substs) => substs.as_closure().tupled_upvars_ty(),
+            UpvarSubsts::Generator(substs) => substs.as_generator().tupled_upvars_ty(),
         };
-        tupled_upvars_ty.expect_ty().tuple_fields()
+
+        match tupled_tys.kind() {
+            TyKind::Error(_) => None,
+            TyKind::Tuple(..) => Some(self.tupled_upvars_ty().tuple_fields()),
+            TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
+            ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
+        }
+        .into_iter()
+        .flatten()
     }
 
     #[inline]