disable use_cache if using gradient checkpointing (#30320)

src/transformers/models/idefics2/modeling_idefics2.py

@@ -1581,6 +1581,12 @@ class Idefics2Model(Idefics2PreTrainedModel):
         use_cache = use_cache if use_cache is not None else self.config.use_cache
         return_dict = return_dict if return_dict is not None else self.config.use_return_dict
 
+        if self.training and self.text_model.gradient_checkpointing and use_cache:
+            logger.warning_once(
+                "`use_cache=True` is incompatible with gradient checkpointing. Setting `use_cache=False`..."
+            )
+            use_cache = False
+
         # retrieve input_ids and inputs_embeds
         if input_ids is not None:
             batch_size, seq_length = input_ids.shape