Generate: `GenerationConfig.from_pretrained` can return unused kwargs (#27488)

src/transformers/generation/configuration_utils.py

@@ -750,6 +750,11 @@ class GenerationConfig(PushToHubMixin):
         else:
             logger.info(f"loading configuration file {configuration_file} from cache at {resolved_config_file}")
 
+        if kwargs.get("return_unused_kwargs") is True:
+            config, unused_kwargs = cls.from_dict(config_dict, **kwargs)
+            config._original_object_hash = hash(config)  # Hash to detect whether the instance was modified
+            return config, unused_kwargs
+        else:
             config = cls.from_dict(config_dict, **kwargs)
             config._original_object_hash = hash(config)  # Hash to detect whether the instance was modified
             return config