Fix breakage due to rust-lang/rust#70551

Author: Xanewok

rust-toolchain

@@ -1 +1 @@
-nightly-2020-06-16
+nightly-2020-06-23

src/mismatch.rs

@@ -135,7 +135,7 @@ impl<'a, 'tcx> TypeRelation<'tcx> for MismatchRelation<'a, 'tcx> {
         use rustc_middle::ty::TyKind;
 
         if self.current_old_types.contains(a) || self.current_new_types.contains(b) {
-            return Ok(self.tcx.types.err);
+            return Ok(self.tcx.types.unit);
         }
 
         self.current_old_types.insert(a);
@@ -279,7 +279,10 @@ impl<'a, 'tcx> TypeRelation<'tcx> for MismatchRelation<'a, 'tcx> {
             }
         }
 
-        Ok(self.tcx.types.err)
+        // FIXME: This used to be a ty_error() placeholder type since this pass
+        // doesn't really relate but is effectful and collects matching items,
+        // therefore it seems it shouldn't matter what we return here
+        Ok(self.tcx.types.unit)
     }
 
     fn regions(

src/translate.rs

@@ -204,14 +204,17 @@ impl<'a, 'tcx> TranslationContext<'a, 'tcx> {
 
                         let success = Cell::new(true);
                         let err_pred = AutoTrait(DefId::local(CRATE_DEF_INDEX));
+                        // A `Self` within original bounds are to be substituted
+                        // with a `trait_object_dummy_self`.
+                        let dummy_self = self.tcx.types.trait_object_dummy_self;
 
                         let res: Vec<_> = preds
                             .iter()
                             .map(|p| {
                                 match *p.skip_binder() {
                                     Trait(existential_trait_ref) => {
                                         let trait_ref = Binder::bind(existential_trait_ref)
-                                            .with_self_ty(self.tcx, self.tcx.types.err);
+                                            .with_self_ty(self.tcx, dummy_self);
                                         let did = trait_ref.skip_binder().def_id;
                                         let substs = trait_ref.skip_binder().substs;
 
@@ -234,7 +237,7 @@ impl<'a, 'tcx> TranslationContext<'a, 'tcx> {
                                     }
                                     Projection(existential_projection) => {
                                         let projection_pred = Binder::bind(existential_projection)
-                                            .with_self_ty(self.tcx, self.tcx.types.err);
+                                            .with_self_ty(self.tcx, dummy_self);
                                         let item_def_id =
                                             projection_pred.skip_binder().projection_ty.item_def_id;
                                         let substs =
@@ -561,7 +564,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for InferenceCleanupFolder<'a, 'tcx> {
                     .tcx
                     .mk_ref(self.infcx.tcx.lifetimes.re_erased, ty_and_mut)
             }
-            TyKind::Infer(_) => self.infcx.tcx.mk_ty(TyKind::Error),
+            TyKind::Infer(_) => self.infcx.tcx.ty_error(),
             _ => t1,
         }
     }