Fixed #29545 -- Fixed using filter lookups againts nested subquery expressions.

Made sql.Where resolve lhs of its child nodes. This is necessary to
allow filter lookups against nested subquery expressions to properly
resolve their OuterRefs to Cols.

Thanks Oskar Persson for the simplified test case.

django/db/models/sql/where.py

@@ -184,18 +184,20 @@ class WhereNode(tree.Node):
         return any(child.is_summary for child in self.children)
 
     @staticmethod
-    def _resolve_rhs(rhs, query, *args, **kwargs):
-        if hasattr(rhs, 'resolve_expression'):
-            rhs = rhs.resolve_expression(query, *args, **kwargs)
-        return rhs
+    def _resolve_leaf(expr, query, *args, **kwargs):
+        if hasattr(expr, 'resolve_expression'):
+            expr = expr.resolve_expression(query, *args, **kwargs)
+        return expr
 
     @classmethod
     def _resolve_node(cls, node, query, *args, **kwargs):
         if hasattr(node, 'children'):
             for child in node.children:
                 cls._resolve_node(child, query, *args, **kwargs)
+        if hasattr(node, 'lhs'):
+            node.lhs = cls._resolve_leaf(node.lhs, query, *args, **kwargs)
         if hasattr(node, 'rhs'):
-            node.rhs = cls._resolve_rhs(node.rhs, query, *args, **kwargs)
+            node.rhs = cls._resolve_leaf(node.rhs, query, *args, **kwargs)
 
     def resolve_expression(self, *args, **kwargs):
         clone = self.clone()

tests/lookup/tests.py

@@ -942,3 +942,17 @@ class LookupTests(TestCase):
             pk_exists=Exists(qs),
         )
         self.assertCountEqual(seasons, Season.objects.all())
+
+    def test_nested_outerref_lhs(self):
+        tag = Tag.objects.create(name=self.au1.alias)
+        tag.articles.add(self.a1)
+        qs = Tag.objects.annotate(
+            has_author_alias_match=Exists(
+                Article.objects.annotate(
+                    author_exists=Exists(
+                        Author.objects.filter(alias=OuterRef(OuterRef('name')))
+                    ),
+                ).filter(author_exists=True)
+            ),
+        )
+        self.assertEqual(qs.get(has_author_alias_match=True), tag)