Fixed #26997 -- Fixed checks crash with empty Meta.default_permissions.

django/contrib/auth/checks.py

@@ -111,7 +111,10 @@ def check_models_permissions(app_configs=None, **kwargs):
         opts = model._meta
         builtin_permissions = dict(_get_builtin_permissions(opts))
         # Check builtin permission name length.
-        max_builtin_permission_name_length = max(len(name) for name in builtin_permissions.values())
+        max_builtin_permission_name_length = (
+            max(len(name) for name in builtin_permissions.values())
+            if builtin_permissions else 0
+        )
         if max_builtin_permission_name_length > permission_name_max_length:
             verbose_name_max_length = (
                 permission_name_max_length - (max_builtin_permission_name_length - len(opts.verbose_name_raw))

docs/releases/1.10.1.txt

@@ -17,3 +17,6 @@ Bugfixes
 
 * Removed the broken ``BaseCommand.usage()`` method which was for
   ``optparse`` support (:ticket:`27000`).
+
+* Fixed a checks framework crash with an empty ``Meta.default_permissions``
+  (:ticket:`26997`).

tests/auth_tests/test_checks.py

@@ -195,3 +195,10 @@ class ModelsPermissionsChecksTests(SimpleTestCase):
                 id='auth.E008',
             ),
         ])
+
+    def test_empty_default_permissions(self):
+        class Checked(models.Model):
+            class Meta:
+                default_permissions = ()
+
+        self.assertEqual(checks.run_checks(self.apps.get_app_configs()), [])