remove assert

Author: lcnr

src/librustc_trait_selection/traits/structural_match.rs

@@ -251,8 +251,7 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {
         // fields of ADT.
         let tcx = self.tcx();
         for field_ty in adt_def.all_fields().map(|field| field.ty(tcx, substs)) {
-            assert!(!field_ty.needs_subst());
-            let ty = self.tcx().normalize_erasing_regions(ty::ParamEnv::reveal_all(), field_ty);
+            let ty = self.tcx().normalize_erasing_regions(ty::ParamEnv::empty(), field_ty);
             debug!("structural-match ADT: field_ty={:?}, ty={:?}", field_ty, ty);
 
             if ty.visit_with(self) {