From c29e3092fdb1136f0945ce2be8f14c3853d6c8da Mon Sep 17 00:00:00 2001
From: Adam Johnson <me@adamj.eu>
Date: Wed, 21 May 2025 16:16:12 +0200
Subject: [PATCH] [5.2.x] Fixed #36404 -- Fixed Aggregate.filter using
 OuterRef.

Regression in a76035e925ff4e6d8676c65cb135c74b993b1039.
Thank you to Simon Charette for the review.

co-authored-by: Simon Charette <charette.s@gmail.com>

Backport of b8e5a8a9a2a767f584cbe89a878a42363706f939 from main.
---
 django/db/models/aggregates.py            |  5 -----
 docs/releases/5.2.2.txt                   |  3 +++
 tests/aggregation/test_filter_argument.py | 21 +++++++++++++++++++++
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/django/db/models/aggregates.py b/django/db/models/aggregates.py
index ea16cc440c..a3a07eb580 100644
--- a/django/db/models/aggregates.py
+++ b/django/db/models/aggregates.py
@@ -61,11 +61,6 @@ class Aggregate(Func):
     ):
         # Aggregates are not allowed in UPDATE queries, so ignore for_save
         c = super().resolve_expression(query, allow_joins, reuse, summarize)
-        c.filter = (
-            c.filter.resolve_expression(query, allow_joins, reuse, summarize)
-            if c.filter
-            else None
-        )
         if summarize:
             # Summarized aggregates cannot refer to summarized aggregates.
             for ref in c.get_refs():
diff --git a/docs/releases/5.2.2.txt b/docs/releases/5.2.2.txt
index 2cf5c750ff..b8deb1c928 100644
--- a/docs/releases/5.2.2.txt
+++ b/docs/releases/5.2.2.txt
@@ -22,3 +22,6 @@ Bugfixes
 * Fixed a regression in Django 5.2 where subclasses of ``RemoteUserMiddleware``
   that had overridden ``process_request()`` were no longer supported
   (:ticket:`36390`).
+
+* Fixed a regression in Django 5.2 that caused a crash when using ``OuterRef``
+  in the ``filter`` argument of an ``Aggregate`` expression (:ticket:`36404`).
diff --git a/tests/aggregation/test_filter_argument.py b/tests/aggregation/test_filter_argument.py
index 75835edb0b..1a17703a86 100644
--- a/tests/aggregation/test_filter_argument.py
+++ b/tests/aggregation/test_filter_argument.py
@@ -84,6 +84,10 @@ class FilteredAggregateTests(TestCase):
                     Author.objects.aggregate(age=agg)["age"], expected_result
                 )
 
+    def test_empty_filtered_aggregates(self):
+        agg = Count("pk", filter=Q())
+        self.assertEqual(Author.objects.aggregate(count=agg)["count"], 3)
+
     def test_double_filtered_aggregates(self):
         agg = Sum("age", filter=Q(Q(name="test2") & ~Q(name="test")))
         self.assertEqual(Author.objects.aggregate(age=agg)["age"], 60)
@@ -182,6 +186,23 @@ class FilteredAggregateTests(TestCase):
         )
         self.assertEqual(aggregate, {"max_rating": 4.5})
 
+    def test_filtered_aggregrate_ref_in_subquery_annotation(self):
+        aggs = (
+            Author.objects.annotate(
+                count=Subquery(
+                    Book.objects.annotate(
+                        weird_count=Count(
+                            "pk",
+                            filter=Q(pages=OuterRef("age")),
+                        )
+                    ).values("weird_count")[:1]
+                ),
+            )
+            .order_by("pk")
+            .aggregate(sum=Sum("count"))
+        )
+        self.assertEqual(aggs["sum"], 0)
+
     def test_filtered_aggregate_on_exists(self):
         aggregate = Book.objects.values("publisher").aggregate(
             max_rating=Max(