1 files changed, 9 insertions, 0 deletions
diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index 86a3a92f07..c270ef16c7 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -405,6 +405,12 @@ class BaseExpression:
         )
         return clone
 
+    def get_refs(self):
+        refs = set()
+        for expr in self.get_source_expressions():
+            refs |= expr.get_refs()
+        return refs
+
     def copy(self):
         return copy.copy(self)
 
@@ -1167,6 +1173,9 @@ class Ref(Expression):
         # just a reference to the name of `source`.
         return self
 
+    def get_refs(self):
+        return {self.refs}
+
     def relabeled_clone(self, relabels):
         return self