fix.diff

diff --git a/compiler/rustc_infer/src/infer/opaque_types.rs b/compiler/rustc_infer/src/infer/opaque_types.rs
index e579afbf389..8c435950977 100644
--- a/compiler/rustc_infer/src/infer/opaque_types.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types.rs
@@ -49,7 +49,7 @@ pub fn replace_opaque_types_with_inference_vars<T: TypeFoldable<'tcx>>(
         span: Span,
         param_env: ty::ParamEnv<'tcx>,
     ) -> InferOk<'tcx, T> {
-        if !value.has_opaque_types() {
+        if !(value.has_opaque_types() || value.has_ty_alias()) {
             return InferOk { value, obligations: vec![] };
         }
         let mut obligations = vec![];
@@ -58,7 +58,7 @@ pub fn replace_opaque_types_with_inference_vars<T: TypeFoldable<'tcx>>(
                 .as_local()
                 .map_or(false, |def_id| self.opaque_type_origin(def_id, span).is_some())
         };
-        let value = value.fold_with(&mut ty::fold::BottomUpFolder {
+        let value = self.tcx.peel_off_ty_alias(value).fold_with(&mut ty::fold::BottomUpFolder {
             tcx: self.tcx,
             lt_op: |lt| lt,
             ct_op: |ct| ct,
@@ -564,7 +564,7 @@ pub fn register_hidden_type(
 
         for predicate in item_bounds.transpose_iter().map(|e| e.map_bound(|(p, _)| *p)) {
             debug!(?predicate);
-            let predicate = predicate.subst(tcx, substs);
+            let predicate = tcx.peel_off_ty_alias(predicate.subst(tcx, substs));
 
             let predicate = predicate.fold_with(&mut BottomUpFolder {
                 tcx,