Fixed #33468 -- Fixed QuerySet.aggregate() after annotate() crash on aggregates with default.

Thanks Adam Johnson for the report.

django/db/models/aggregates.py

@@ -65,7 +65,9 @@ class Aggregate(Func):
         if hasattr(default, 'resolve_expression'):
             default = default.resolve_expression(query, allow_joins, reuse, summarize)
         c.default = None  # Reset the default argument before wrapping.
-        return Coalesce(c, default, output_field=c._output_field_or_none)
+        coalesce = Coalesce(c, default, output_field=c._output_field_or_none)
+        coalesce.is_summary = c.is_summary
+        return coalesce
 
     @property
     def default_alias(self):

docs/releases/4.0.2.txt

@@ -33,3 +33,7 @@ Bugfixes
 * Fixed a duplicate operation regression in Django 4.0 that caused a migration
   crash when altering a primary key type for a concrete parent model referenced
   by a foreign key (:ticket:`33462`).
+
+* Fixed a bug in Django 4.0 that caused a crash of ``QuerySet.aggregate()``
+  after ``annotate()`` on an aggregate function with a
+  :ref:`default <aggregate-default>` (:ticket:`33468`).

tests/aggregation/tests.py

@@ -1630,6 +1630,18 @@ class AggregateTestCase(TestCase):
         )
         self.assertAlmostEqual(result['value'], Decimal('61.72'), places=2)
 
+    def test_aggregation_default_after_annotation(self):
+        result = Publisher.objects.annotate(
+            double_num_awards=F('num_awards') * 2,
+        ).aggregate(value=Sum('double_num_awards', default=0))
+        self.assertEqual(result['value'], 40)
+
+    def test_aggregation_default_not_in_aggregate(self):
+        result = Publisher.objects.annotate(
+            avg_rating=Avg('book__rating', default=2.5),
+        ).aggregate(Sum('num_awards'))
+        self.assertEqual(result['num_awards__sum'], 20)
+
     def test_exists_none_with_aggregate(self):
         qs = Book.objects.all().annotate(
             count=Count('id'),