Refs #25367 -- Made Query.build_filter() raise TypeError on non-conditional expressions.

django/db/models/sql/query.py

@@ -1230,7 +1230,9 @@ class Query(BaseExpression):
                 allow_joins=allow_joins,
                 split_subq=split_subq,
             )
-        if hasattr(filter_expr, 'resolve_expression') and getattr(filter_expr, 'conditional', False):
+        if hasattr(filter_expr, 'resolve_expression'):
+            if not getattr(filter_expr, 'conditional', False):
+                raise TypeError('Cannot filter against a non-conditional expression.')
             condition = self.build_lookup(
                 ['exact'], filter_expr.resolve_expression(self, allow_joins=allow_joins), True
             )

tests/queries/test_query.py

@@ -144,3 +144,9 @@ class TestQuery(SimpleTestCase):
         msg = 'Joined field references are not permitted in this query'
         with self.assertRaisesMessage(FieldError, msg):
             query.build_where(filter_expr)
+
+    def test_filter_non_conditional(self):
+        query = Query(Item)
+        msg = 'Cannot filter against a non-conditional expression.'
+        with self.assertRaisesMessage(TypeError, msg):
+            query.build_where(Func(output_field=CharField()))