Fixed #30011 -- Fixed queries that reuse filtered aggregates.

Thanks Taqi Abbas and Raphael Kimmig for the report.

2 files changed, 9 insertions, 1 deletions

diff --git a/django/db/models/aggregates.py b/django/db/models/aggregates.py
index cc4b0c52a6..b270640ea5 100644
--- a/django/db/models/aggregates.py
+++ b/django/db/models/aggregates.py
@@ -27,7 +27,7 @@ class Aggregate(Func):
     def get_source_expressions(self):
         source_expressions = super().get_source_expressions()
         if self.filter:
-            source_expressions += [self.filter]
+            return source_expressions + [self.filter]
         return source_expressions
 
     def set_source_expressions(self, exprs):
diff --git a/tests/aggregation/test_filter_argument.py b/tests/aggregation/test_filter_argument.py
index 54836178c4..63dee59464 100644
--- a/tests/aggregation/test_filter_argument.py
+++ b/tests/aggregation/test_filter_argument.py
@@ -79,3 +79,11 @@ class FilteredAggregateTests(TestCase):
         msg = 'Star cannot be used with filter. Please specify a field.'
         with self.assertRaisesMessage(ValueError, msg):
             Count('*', filter=Q(age=40))
+
+    def test_filtered_reused_subquery(self):
+        qs = Author.objects.annotate(
+            older_friends_count=Count('friends', filter=Q(friends__age__gt=F('age'))),
+        ).filter(
+            older_friends_count__gte=2,
+        )
+        self.assertEqual(qs.get(pk__in=qs.values('pk')), self.a1)