Fix alias() not compatible with specific()

Fixes #11285

# Conflicts:
#	CHANGELOG.txt
#	docs/releases/6.0.md

wagtail/query.py

@@ -515,7 +515,7 @@ class SpecificIterable(BaseIterable):
         in the same order, with any annotations intact.
         """
         qs = self.queryset
-        annotation_aliases = qs.query.annotations.keys()
+        annotation_aliases = qs.query.annotation_select
         values_qs = qs.values("pk", "content_type", *annotation_aliases)
 
         # Gather items in batches to reduce peak memory usage

wagtail/tests/test_page_queryset.py

@@ -920,6 +920,25 @@ class TestSpecificQuery(WagtailTestUtils, TestCase):
         self.assertEqual(results.first().subscribers_count, 1)
         self.assertEqual(results.last().subscribers_count, 1)
 
+    def test_specific_query_with_alias(self):
+        """
+        Ensure alias() works with specific() queries.
+        See https://github.com/wagtail/wagtail/issues/11285 for more details
+        """
+
+        pages = Page.objects.live()
+        user = self.create_test_user()
+        pages.first().subscribers.create(user=user, comment_notifications=False)
+        pages.last().subscribers.create(user=user, comment_notifications=False)
+
+        # This would previously fail as described in #11285.
+        iter(
+            Page.objects.live()
+            .specific()
+            .alias(subscribers_count=Count("subscribers"))
+            .order_by("subscribers_count")
+        )
+
     def test_specific_gracefully_handles_missing_models(self):
         # 3567 - PageQuerySet.specific should gracefully handle pages whose class definition
         # is missing, by keeping them as basic Page instances.