[core] remove GenerationMixin inheritance by default in PreTrainedModel

src/transformers/generation/utils.py

@@ -1430,27 +1430,6 @@ def compute_transition_scores(
 
         return transition_scores
 
-    def _validate_model_class(self):
-        """
-        Confirms that the model class is compatible with generation. If not, raises an exception that points to the
-        right class to use.
-        """
-        # TODO(joao): remove this function in v4.50, i.e. when we remove the inheritance of `GenerationMixin` from
-        # `PreTrainedModel`. With that inheritance removed, all model classes inheriting from `GenerationMixin` can
-        # safely call `GenerationMixin.generate`
-        if not self.can_generate():
-            terminations_with_generation_support = [
-                "ForCausalLM",
-                "ForConditionalGeneration",
-                "ForSpeechSeq2Seq",
-                "ForVision2Seq",
-            ]
-            raise TypeError(
-                f"The current model class ({self.__class__.__name__}) is not compatible with `.generate()`, as "
-                "it doesn't have a language model head. Classes that support generation often end in one of these "
-                f"names: {terminations_with_generation_support}."
-            )
-
     def _validate_assistant(self, assistant_model, tokenizer, assistant_tokenizer):
         if assistant_model is None:
             return
@@ -2213,7 +2192,6 @@ def generate(
         """
 
         # 1. Handle `generation_config` and kwargs that might update it, and validate the `.generate()` call
-        self._validate_model_class()
         tokenizer = kwargs.pop("tokenizer", None)  # Pull this out first, we only use it for stopping criteria
         assistant_tokenizer = kwargs.pop("assistant_tokenizer", None)  # only used for assisted generation
 

src/transformers/modeling_utils.py

@@ -55,7 +55,7 @@
 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 @@ def floating_point_ops(
         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 @@ def can_generate(cls) -> bool:
                 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 @@ def can_generate(cls) -> bool:
                 "\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
 

src/transformers/models/auto/auto_factory.py

@@ -730,8 +730,12 @@ def add_generation_mixin_to_remote_model(model_class):
 
     # 3. Prior to v4.45, we could detect whether a model was `generate`-compatible if it had its own `generate` and/or
     # `prepare_inputs_for_generation` method.
-    has_custom_generate = "GenerationMixin" not in str(getattr(model_class, "generate"))
-    has_custom_prepare_inputs = "GenerationMixin" not in str(getattr(model_class, "prepare_inputs_for_generation"))
+    has_custom_generate = hasattr(model_class, "generate") and "GenerationMixin" not in str(
+        getattr(model_class, "generate")
+    )
+    has_custom_prepare_inputs = hasattr(model_class, "prepare_inputs_for_generation") and "GenerationMixin" not in str(
+        getattr(model_class, "prepare_inputs_for_generation")
+    )
     if has_custom_generate or has_custom_prepare_inputs:
         model_class_with_generation_mixin = type(
             model_class.__name__, (model_class, GenerationMixin), {**model_class.__dict__}

src/transformers/models/bert/modeling_bert.py

@@ -1512,8 +1512,8 @@ def prepare_inputs_for_generation(self, input_ids, attention_mask=None, **model_
     @classmethod
     def can_generate(cls) -> bool:
         """
-        Legacy correction: BertForMaskedLM can't call `generate()` from GenerationMixin.
-        Remove after v4.50, when we stop making `PreTrainedModel` inherit from `GenerationMixin`.
+        Legacy correction: BertForMaskedLM can't call `generate()` from `GenerationMixin`, even though it has a
+        `prepare_inputs_for_generation` method.
         """
         return False
 

src/transformers/models/ernie/modeling_ernie.py

@@ -1328,8 +1328,8 @@ def prepare_inputs_for_generation(self, input_ids, attention_mask=None, **model_
     @classmethod
     def can_generate(cls) -> bool:
         """
-        Legacy correction: ErnieForMaskedLM can't call `generate()` from GenerationMixin.
-        Remove after v4.50, when we stop making `PreTrainedModel` inherit from `GenerationMixin`.
+        Legacy correction: ErnieForMaskedLM can't call `generate()` from `GenerationMixin`, even though it has a
+        `prepare_inputs_for_generation` method.
         """
         return False
 

src/transformers/models/rag/modeling_rag.py

@@ -22,7 +22,7 @@
 from torch import nn
 
 from ...configuration_utils import PretrainedConfig
-from ...generation import GenerationConfig, LogitsProcessorList, StoppingCriteriaList
+from ...generation import GenerationConfig, GenerationMixin, LogitsProcessorList, StoppingCriteriaList
 from ...modeling_outputs import ModelOutput
 from ...modeling_utils import PreTrainedModel
 from ...utils import add_start_docstrings_to_model_forward, logging, replace_return_docstrings
@@ -1122,7 +1122,7 @@ def _cat_and_pad(tensors, pad_token_id):
     """,
     RAG_START_DOCSTRING,
 )
-class RagTokenForGeneration(RagPreTrainedModel):
+class RagTokenForGeneration(RagPreTrainedModel, GenerationMixin):
     def __init__(
         self,
         config: Optional[PretrainedConfig] = None,

src/transformers/models/rembert/modeling_rembert.py

@@ -999,6 +999,14 @@ def prepare_inputs_for_generation(self, input_ids, attention_mask=None, **model_
 
         return {"input_ids": input_ids, "attention_mask": attention_mask}
 
+    @classmethod
+    def can_generate(cls) -> bool:
+        """
+        Legacy correction: RemBertForMaskedLM can't call `generate()` from `GenerationMixin`, even though it has a
+        `prepare_inputs_for_generation` method.
+        """
+        return False
+
 
 @add_start_docstrings(
     """RemBERT Model with a `language modeling` head on top for CLM fine-tuning.""", REMBERT_START_DOCSTRING

src/transformers/models/speecht5/modeling_speecht5.py

@@ -24,6 +24,7 @@
 from torch.nn import BCEWithLogitsLoss, CrossEntropyLoss, L1Loss
 
 from ...activations import ACT2FN
+from ...generation import GenerationMixin
 from ...integrations.deepspeed import is_deepspeed_zero3_enabled
 from ...integrations.fsdp import is_fsdp_managed_module
 from ...modeling_attn_mask_utils import _prepare_4d_attention_mask, _prepare_4d_causal_attention_mask
@@ -2242,7 +2243,7 @@ def forward(
     """SpeechT5 Model with a speech encoder and a text decoder.""",
     SPEECHT5_START_DOCSTRING,
 )
-class SpeechT5ForSpeechToText(SpeechT5PreTrainedModel):
+class SpeechT5ForSpeechToText(SpeechT5PreTrainedModel, GenerationMixin):
     _tied_weights_keys = ["text_decoder_postnet.lm_head.weight"]
 
     def __init__(self, config: SpeechT5Config):
@@ -2413,44 +2414,6 @@ def forward(
             encoder_attentions=outputs.encoder_attentions,
         )
 
-    def prepare_inputs_for_generation(
-        self,
-        decoder_input_ids,
-        past_key_values=None,
-        attention_mask=None,
-        head_mask=None,
-        decoder_head_mask=None,
-        cross_attn_head_mask=None,
-        use_cache=None,
-        encoder_outputs=None,
-        **kwargs,
-    ):
-        # Note that this model doesn't inherit from the generation mixin, has unique generate function
-
-        # cut decoder_input_ids if past is used
-        if past_key_values is not None:
-            past_length = past_key_values[0][0].shape[2]
-
-            # Some generation methods already pass only the last input ID
-            if decoder_input_ids.shape[1] > past_length:
-                remove_prefix_length = past_length
-            else:
-                # Default to old behavior: keep only final ID
-                remove_prefix_length = decoder_input_ids.shape[1] - 1
-
-            decoder_input_ids = decoder_input_ids[:, remove_prefix_length:]
-
-        return {
-            "encoder_outputs": encoder_outputs,
-            "past_key_values": past_key_values,
-            "decoder_input_ids": decoder_input_ids,
-            "attention_mask": attention_mask,
-            "head_mask": head_mask,
-            "decoder_head_mask": decoder_head_mask,
-            "cross_attn_head_mask": cross_attn_head_mask,
-            "use_cache": use_cache,  # change this to avoid caching (presumably for debugging)
-        }
-
     @staticmethod
     def _reorder_cache(past_key_values, beam_idx):
         reordered_past = ()

tests/models/speecht5/test_modeling_speecht5.py

@@ -31,6 +31,7 @@
 from transformers.trainer_utils import set_seed
 from transformers.utils import cached_property
 
+from ...generation.test_utils import GenerationTesterMixin
 from ...test_configuration_common import ConfigTester
 from ...test_modeling_common import (
     ModelTesterMixin,
@@ -314,6 +315,15 @@ def get_config(self):
             vocab_size=self.vocab_size,
         )
 
+    def get_subsampled_output_lengths(self, input_lengths):
+        """
+        Computes the output length of the convolutional layers
+        """
+        for stride in self.conv_stride:
+            input_lengths = (input_lengths // stride) - 1
+
+        return input_lengths
+
     def create_and_check_model_forward(self, config, inputs_dict):
         model = SpeechT5ForSpeechToText(config=config).to(torch_device).eval()
 
@@ -359,10 +369,8 @@ def create_and_check_decoder_model_past_large_inputs(self, config, inputs_dict):
 
 
 @require_torch
-class SpeechT5ForSpeechToTextTest(ModelTesterMixin, unittest.TestCase):
+class SpeechT5ForSpeechToTextTest(ModelTesterMixin, unittest.TestCase, GenerationTesterMixin):
     all_model_classes = (SpeechT5ForSpeechToText,) if is_torch_available() else ()
-    # Doesn't run generation tests. TODO eustache/joao: shape checks probably need an update
-    all_generative_model_classes = ()
     is_encoder_decoder = True
     test_pruning = False
     test_headmasking = False
@@ -727,6 +735,18 @@ def _mock_init_weights(self, module):
         if hasattr(module, "masked_spec_embed") and module.masked_spec_embed is not None:
             module.masked_spec_embed.data.fill_(3)
 
+    @unittest.skip(reason="Temporarily broken")  # TODO (joao, eustache): have a look at this test
+    def test_generate_with_head_masking(self):
+        pass
+
+    @unittest.skip(reason="Temporarily broken")  # TODO (joao, eustache): have a look at this test
+    def test_generate_without_input_ids(self):
+        pass
+
+    @unittest.skip(reason="Very flaky")  # TODO (joao, eustache): have a look at this test
+    def test_generate_continue_from_past_key_values(self):
+        pass
+
 
 @require_torch
 @require_sentencepiece

tests/utils/test_modeling_utils.py

@@ -1720,16 +1720,16 @@ class DummyBertWithParent(DummyBertWithMixin):
         self.assertTrue("" == cl.out)
         self.assertTrue(can_generate)
 
-        # 4 - BC: models with a custom `prepare_inputs_for_generation` can generate (it was assumed they inherited
-        # `GenerationMixin`)
+        # 4 - Legacy: models with a custom `prepare_inputs_for_generation` can generate (it was assumed
+        # they inherited `GenerationMixin`). Deprecated in v4.45 and removed in v4.51.
         class DummyBertWithPrepareInputs(BertModel):
             def prepare_inputs_for_generation(self):
                 pass
 
         with CaptureLogger(logger) as cl:
             can_generate = DummyBertWithPrepareInputs.can_generate()
         self.assertTrue("it doesn't directly inherit from `GenerationMixin`" in cl.out)
-        self.assertTrue(can_generate)
+        self.assertFalse(can_generate)
 
     def test_save_and_load_config_with_custom_generation(self):
         """