Make `needs_drop` less pessimistic on generators

1 files changed, 17 insertions, 0 deletions

diff --git a/src/librustc_ty/needs_drop.rs b/src/librustc_ty/needs_drop.rs
index 6b0104e164b..515cf6f2911 100644
--- a/src/librustc_ty/needs_drop.rs
+++ b/src/librustc_ty/needs_drop.rs
@@ -99,6 +99,23 @@ where
                         }
                     }
 
+                    ty::Generator(def_id, substs, _) => {
+                        let substs = substs.as_generator();
+                        for upvar_ty in substs.upvar_tys(def_id, tcx) {
+                            queue_type(self, upvar_ty);
+                        }
+
+                        let witness = substs.witness(def_id, tcx);
+                        let interior_tys = match &witness.kind {
+                            ty::GeneratorWitness(tys) => tcx.erase_late_bound_regions(tys),
+                            _ => bug!(),
+                        };
+
+                        for interior_ty in interior_tys {
+                            queue_type(self, interior_ty);
+                        }
+                    }
+
                     // Check for a `Drop` impl and whether this is a union or
                     // `ManuallyDrop`. If it's a struct or enum without a `Drop`
                     // impl then check whether the field types need `Drop`.