[core] remove GenerationMixin inheritance by default in PreTrainedModel (#37173)

src/transformers/modeling_utils.py

@@ -55,7 +55,7 @@ if is_torchao_available():
 from .activations import get_activation
 from .configuration_utils import PretrainedConfig
 from .dynamic_module_utils import custom_object_save
-from .generation import CompileConfig, GenerationConfig, GenerationMixin
+from .generation import CompileConfig, GenerationConfig
 from .integrations import PeftAdapterMixin, deepspeed_config, is_deepspeed_zero3_enabled
 from .integrations.accelerate import find_tied_parameters, init_empty_weights
 from .integrations.deepspeed import _load_state_dict_into_zero3_model, is_deepspeed_available
@@ -1704,8 +1704,7 @@ class ModuleUtilsMixin:
         return 6 * self.estimate_tokens(input_dict) * self.num_parameters(exclude_embeddings=exclude_embeddings)
 
 
-# TODO (joao): remove `GenerationMixin` inheritance in v4.50
-class PreTrainedModel(nn.Module, ModuleUtilsMixin, GenerationMixin, PushToHubMixin, PeftAdapterMixin):
+class PreTrainedModel(nn.Module, ModuleUtilsMixin, PushToHubMixin, PeftAdapterMixin):
     r"""
     Base class for all models.
 
@@ -2157,12 +2156,12 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin, GenerationMixin, PushToHubMix
                 continue
             if "PreTrainedModel" not in str(base) and base.can_generate():
                 return True
-        # BC: Detects whether `prepare_inputs_for_generation` has been overwritten in the model. Prior to v4.45, this
+        # Detects whether `prepare_inputs_for_generation` has been overwritten in the model. Prior to v4.45, this
         # was how we detected whether a model could generate.
-        if "GenerationMixin" not in str(cls.prepare_inputs_for_generation):
-            logger.warning_once(
+        if hasattr(cls, "prepare_inputs_for_generation"):  # implicit: doesn't inherit `GenerationMixin`
+            logger.warning(
                 f"{cls.__name__} has generative capabilities, as `prepare_inputs_for_generation` is explicitly "
-                "overwritten. However, it doesn't directly inherit from `GenerationMixin`. From 👉v4.50👈 onwards, "
+                "defined. However, it doesn't directly inherit from `GenerationMixin`. From 👉v4.50👈 onwards, "
                 "`PreTrainedModel` will NOT inherit from `GenerationMixin`, and this model will lose the ability "
                 "to call `generate` and other related functions."
                 "\n  - If you're using `trust_remote_code=True`, you can get rid of this warning by loading the "
@@ -2172,7 +2171,6 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin, GenerationMixin, PushToHubMix
                 "\n  - If you are not the owner of the model architecture class, please contact the model code owner "
                 "to update it."
             )
-            return True
         # Otherwise, can't generate
         return False