Refs #22997 -- Prevented requesting a default value for auto fields.

django/db/migrations/autodetector.py

@@ -1132,6 +1132,7 @@ class MigrationAutodetector:
         # You can't just add NOT NULL fields with no default or fields
         # which don't allow empty strings as default.
         time_fields = (models.DateField, models.DateTimeField, models.TimeField)
+        auto_fields = (models.AutoField, models.SmallAutoField, models.BigAutoField)
         preserve_default = (
             field.null
             or field.has_default()
@@ -1139,6 +1140,7 @@ class MigrationAutodetector:
             or field.many_to_many
             or (field.blank and field.empty_strings_allowed)
             or (isinstance(field, time_fields) and field.auto_now)
+            or (isinstance(field, auto_fields))
         )
         if not preserve_default:
             field = field.clone()

tests/migrations/test_autodetector.py

@@ -1595,6 +1595,34 @@ class AutodetectorTests(BaseAutodetectorTests):
             changes, "testapp", 0, 0, db_default="Ada Lovelace"
         )
 
+    @mock.patch(
+        "django.db.migrations.questioner.MigrationQuestioner.ask_not_null_addition"
+    )
+    def test_add_auto_field_does_not_request_default(self, mocked_ask_method):
+        initial_state = ModelState(
+            "testapp",
+            "Author",
+            [
+                ("pkfield", models.IntegerField(primary_key=True)),
+            ],
+        )
+        for auto_field in [
+            models.AutoField,
+            models.BigAutoField,
+            models.SmallAutoField,
+        ]:
+            with self.subTest(auto_field=auto_field):
+                updated_state = ModelState(
+                    "testapp",
+                    "Author",
+                    [
+                        ("id", auto_field(primary_key=True)),
+                        ("pkfield", models.IntegerField(primary_key=False)),
+                    ],
+                )
+                self.get_changes([initial_state], [updated_state])
+                mocked_ask_method.assert_not_called()
+
     @mock.patch(
         "django.db.migrations.questioner.MigrationQuestioner.ask_not_null_alteration",
         return_value=models.NOT_PROVIDED,