Merge "Alias the onclause if ORM join is to same polymorphic selectable"

2 files changed, 4 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py
index ab49a4dcc..98e997078 100644
--- a/lib/sqlalchemy/orm/query.py
+++ b/lib/sqlalchemy/orm/query.py
@@ -2762,7 +2762,6 @@ class Query(Generative):
             elif prop:
                 # joining to selectable with a mapper property given
                 # as the ON clause
-
                 if not right_selectable.is_derived_from(
                     right_mapper.persist_selectable
                 ):
diff --git a/lib/sqlalchemy/orm/relationships.py b/lib/sqlalchemy/orm/relationships.py
index 6ac56a324..85f23d159 100644
--- a/lib/sqlalchemy/orm/relationships.py
+++ b/lib/sqlalchemy/orm/relationships.py
@@ -2377,7 +2377,10 @@ class RelationshipProperty(StrategizedProperty):
             if self._is_self_referential and source_selectable is None:
                 dest_selectable = dest_selectable._anonymous_fromclause()
                 aliased = True
-        elif dest_selectable is not self.mapper._with_polymorphic_selectable:
+        elif (
+            dest_selectable is not self.mapper._with_polymorphic_selectable
+            or self.mapper.with_polymorphic
+        ):
             aliased = True
 
         dest_mapper = of_type_mapper or self.mapper