cosmetic changes

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -2635,10 +2635,16 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         if let Err(_) = self.eq_substs(
             typeck_root_substs,
             parent_substs,
-            Locations::Single(location),
+            location.to_locations(),
             ConstraintCategory::BoringNoLocation,
         ) {
-            bug!("we shouldn't error, this should only impose region constraints");
+            span_mirbug!(
+                self,
+                def_id,
+                "could not relate closure to parent {:?} != {:?}",
+                typeck_root_substs,
+                parent_substs
+            );
         }
 
         tcx.predicates_of(def_id).instantiate(tcx, substs)

compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -47,12 +47,12 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         locations: Locations,
         category: ConstraintCategory<'tcx>,
     ) -> Fallible<()> {
-        let mut relation = TypeRelating::new(
+        TypeRelating::new(
             self.infcx,
             NllTypeRelatingDelegate::new(self, locations, category, UniverseInfo::other()),
             ty::Variance::Invariant,
-        );
-        ty::relate::relate_substs(&mut relation, a, b)?;
+        )
+        .relate(a, b)?;
         Ok(())
     }
 }