squash OpaqueTy and ProjectionTy into AliasTy

compiler/rustc_hir_analysis/src/check/check.rs

@@ -1440,7 +1440,7 @@ fn opaque_type_cycle_error(tcx: TyCtxt<'_>, def_id: LocalDefId, span: Span) -> E
                 impl<'tcx> ty::visit::TypeVisitor<'tcx> for OpaqueTypeCollector {
                     fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
                         match *t.kind() {
-                            ty::Opaque(ty::OpaqueTy { def_id: def, substs: _ }) => {
+                            ty::Opaque(ty::AliasTy { def_id: def, substs: _ }) => {
                                 self.0.push(def);
                                 ControlFlow::CONTINUE
                             }

compiler/rustc_hir_analysis/src/check/compare_method.rs

@@ -1746,7 +1746,7 @@ pub fn check_type_bounds<'tcx>(
             _ => predicates.push(
                 ty::Binder::bind_with_vars(
                     ty::ProjectionPredicate {
-                        projection_ty: ty::ProjectionTy {
+                        projection_ty: ty::AliasTy {
                             def_id: trait_ty.def_id,
                             substs: rebased_substs,
                         },