Fix deprecated arg issue (#29372)

* Fix deprecated arg issue

* Trainer check too

* Check for dict or dataclass

* Simplify, make config always AcceleratorConfig

* Upstream to Trainer

tests/trainer/test_trainer.py

@@ -2633,6 +2633,20 @@ class TrainerIntegrationTest(TestCasePlus, TrainerIntegrationCommon):
             self.assertEqual(trainer.accelerator.even_batches, False)
             self.assertEqual(trainer.accelerator.dispatch_batches, None)
 
+    def test_accelerator_config_only_deprecated_args(self):
+        with tempfile.TemporaryDirectory() as tmp_dir:
+            with self.assertWarns(FutureWarning) as cm:
+                args = RegressionTrainingArguments(
+                    output_dir=tmp_dir,
+                    split_batches=True,
+                )
+                self.assertIn("split_batches", str(cm.warnings[0].message))
+                config = RegressionModelConfig(a=1.5, b=2.5)
+                model = RegressionPreTrainedModel(config)
+                eval_dataset = SampleIterableDataset()
+                trainer = Trainer(model=model, args=args, eval_dataset=eval_dataset)
+                self.assertEqual(trainer.accelerator.split_batches, True)
+
 
 @require_torch
 @is_staging_test