[core] Fix attn_implementation setter with missing sub_configs (#39855)

* fix

* add sub_configs

* remove case for attention setter

* fix None

* Add test

* Fix sub-configs

* fix tests_config

* fix consistency

* fix fsmt

* fix

tests/test_configuration_common.py

@@ -141,6 +141,7 @@ class ConfigTester:
                 # Verify that loading with subconfig class results in same dict as if we loaded with general composite config class
                 sub_config_loaded_dict = sub_config_loaded.to_dict()
                 sub_config_loaded_dict.pop("transformers_version", None)
+                general_config_dict[sub_config_key].pop("transformers_version", None)
                 self.parent.assertEqual(sub_config_loaded_dict, general_config_dict[sub_config_key])
 
                 # Verify that the loaded config type is same as in the general config

tests/test_modeling_common.py

@@ -4812,6 +4812,25 @@ class ModelTesterMixin:
                 f"All parameters should be on meta device, but found {unique_devices}.",
             )
 
+    def test_config_attn_implementation_setter(self):
+        config, _ = self.model_tester.prepare_config_and_inputs_for_common()
+
+        def check_attn_implementation_setter(config: PretrainedConfig, attn_implementation: str):
+            if not config._attn_implementation == attn_implementation:
+                raise ValueError(
+                    f"Unexpected attn_implementation for config {config.__class__.__name__}: "
+                    f"{config._attn_implementation} != {attn_implementation}"
+                )
+            for attribute_value in config.__dict__.values():
+                if isinstance(attribute_value, PretrainedConfig):
+                    check_attn_implementation_setter(attribute_value, attn_implementation)
+
+        config._attn_implementation = "eager"
+        check_attn_implementation_setter(config, "eager")
+
+        config._attn_implementation = "sdpa"
+        check_attn_implementation_setter(config, "sdpa")
+
     def test_internal_model_config_and_subconfig_are_same(self):
         config, _ = self.model_tester.prepare_config_and_inputs_for_common()
         subconfig_keys = list(config.sub_configs.keys())