Generate: better warnings with pipelines (#23128)

src/transformers/pipelines/base.py

@@ -803,10 +803,12 @@ class Pipeline(_ScikitCompat):
         self.torch_dtype = torch_dtype
         self.binary_output = binary_output
 
-        # Update config with task specific parameters
+        # Update config and generation_config with task specific parameters
         task_specific_params = self.model.config.task_specific_params
         if task_specific_params is not None and task in task_specific_params:
             self.model.config.update(task_specific_params.get(task))
+            if self.model.can_generate():
+                self.model.generation_config.update(**task_specific_params.get(task))
 
         self.call_count = 0
         self._batch_size = kwargs.pop("batch_size", None)

src/transformers/pipelines/text2text_generation.py

@@ -273,7 +273,8 @@ class SummarizationPipeline(Text2TextGenerationPipeline):
 
         if input_length < max_length:
             logger.warning(
-                f"Your max_length is set to {max_length}, but your input_length is only {input_length}. You might "
+                f"Your max_length is set to {max_length}, but your input_length is only {input_length}. Since this is "
+                "a summarization task, where outputs shorter than the input are typically wanted, you might "
                 f"consider decreasing max_length manually, e.g. summarizer('...', max_length={input_length//2})"
             )