Repository: huggingface/transformers
File: src/transformers/trainer.py (Python)

Code before:
    def compute_loss(self, model, inputs, return_outputs=False, num_items_in_batch=None):
        """
        How the loss is computed by Trainer. By default, all models return the loss in the first element.

        Subclass and override for custom behavior.
        """
        if (self.label_smoother is not None or self.compute_loss_func is not None) and "labels" in inputs:
            labels = inputs.pop("labels")
        else:
            labels = None
        if num_items_in_batch is not None:
            inputs["num_items_in_batch"] = num_items_in_batch
        outputs = model(**inputs)
        # Save past state if it exists
        # TODO: this needs to be fixed and made cleaner later.
        if self.args.past_index >= 0:
            self._past = outputs[self.args.past_index]

        if labels is not None:
            unwrapped_model = self.accelerator.unwrap_model(model)
            if _is_peft_model(unwrapped_model):
                model_name = unwrapped_model.base_model.model._get_name()
            else:
                model_name = unwrapped_model._get_name()
            # User-defined compute_loss function
            if self.compute_loss is not None:
                loss = self.compute_loss_func(outputs, labels, num_items_in_batch=num_items_in_batch)
            elif model_name in MODEL_FOR_CAUSAL_LM_MAPPING_NAMES.values():
                loss = self.label_smoother(outputs, labels, shift_labels=True)
            else:
                loss = self.label_smoother(outputs, labels)
        else:
            if isinstance(outputs, dict) and "loss" not in outputs:
                raise ValueError(
                    "The model did not return a loss from the inputs, only the following keys: "
                    f"{','.join(outputs.keys())}. For reference, the inputs it received are {','.join(inputs.keys())}."
                )
            # We don't use .loss here since the model may return tuples instead of ModelOutput.
            loss = outputs["loss"] if isinstance(outputs, dict) else outputs[0]

        return (loss, outputs) if return_outputs else loss

    def is_local_process_zero(self) -> bool:
        """
        Whether or not this process is the local (e.g., on one machine if training in a distributed fashion on several
        machines) main process.
        """
        return self.args.local_process_index == 0

    def is_world_process_zero(self) -> bool:
        """

Review comment (suggestion):
```suggestion
            if self.compute_loss_func is not None:
```

Code after:
                raise ValueError(
                    "The model did not return a loss from the inputs, only the following keys: "
                    f"{','.join(outputs.keys())}. For reference, the inputs it received are {','.join(inputs.keys())}."
                )
            # We don't use .loss here since the model may return tuples instead of ModelOutput.
            loss = outputs["loss"] if isinstance(outputs, dict) else outputs[0]

        return (loss, outputs) if return_outputs else loss

    def is_local_process_zero(self) -> bool:
        """
        Whether or not this process is the local (e.g., on one machine if training in a distributed fashion on several
        machines) main process.
        """
        return self.args.local_process_index == 0

    def is_world_process_zero(self) -> bool:
        """
        Whether or not this process is the global main process (when training in a distributed fashion on several
        machines, this is only going to be `True` for one process).
        """
        # Special case for SageMaker ModelParallel since there process_index is dp_process_index, not the global
        # process index.
        if is_sagemaker_mp_enabled():
            return smp.rank() == 0
        else:
            return self.args.process_index == 0

    def save_model(self, output_dir: Optional[str] = None, _internal_call: bool = False):
        """
        Will save the model, so you can reload it using `from_pretrained()`.

        Will only save from the main process.
        """

        if output_dir is None:
            output_dir = self.args.output_dir

        if is_torch_xla_available():
            self._save_tpu(output_dir)
        elif is_sagemaker_mp_enabled():
            # Calling the state_dict needs to be done on the wrapped model and on all processes.
            os.makedirs(output_dir, exist_ok=True)
            state_dict = self.model_wrapped.state_dict()
            if self.args.should_save:
                self._save(output_dir, state_dict=state_dict)
            if IS_SAGEMAKER_MP_POST_1_10:
                # 'user_content.pt' indicates model state_dict saved with smp >= 1.10
                Path(os.path.join(output_dir, "user_content.pt")).touch()
        elif self.is_fsdp_enabled:
            if ("FULL_STATE_DICT" in str(self.accelerator.state.fsdp_plugin.state_dict_type)) and (