1 files changed, 9 insertions, 0 deletions
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index d105d24bed7..9d3886aff1c 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -764,6 +764,7 @@ impl<'tcx> InferCtxt<'tcx> {
         let r_b = self.shallow_resolve(predicate.skip_binder().b);
         match (r_a.kind(), r_b.kind()) {
             (&ty::Infer(ty::TyVar(a_vid)), &ty::Infer(ty::TyVar(b_vid))) => {
+                self.sub_unify_ty_vids_raw(a_vid, b_vid);
                 return Err((a_vid, b_vid));
             }
             _ => {}
@@ -1128,6 +1129,14 @@ impl<'tcx> InferCtxt<'tcx> {
         self.inner.borrow_mut().type_variables().root_var(var)
     }
 
+    pub fn sub_unify_ty_vids_raw(&self, a: ty::TyVid, b: ty::TyVid) {
+        self.inner.borrow_mut().type_variables().sub_unify(a, b);
+    }
+
+    pub fn sub_unification_table_root_var(&self, var: ty::TyVid) -> ty::TyVid {
+        self.inner.borrow_mut().type_variables().sub_unification_table_root_var(var)
+    }
+
     pub fn root_const_var(&self, var: ty::ConstVid) -> ty::ConstVid {
         self.inner.borrow_mut().const_unification_table().find(var).vid
     }