check for key 'torch.dtype' in nested dicts in config (#16065)

src/transformers/configuration_utils.py

@@ -849,12 +849,15 @@ class PretrainedConfig(PushToHubMixin):
 
     def dict_torch_dtype_to_str(self, d: Dict[str, Any]) -> None:
         """
-        Checks whether the passed dictionary has a *torch_dtype* key and if it's not None, converts torch.dtype to a
-        string of just the type. For example, `torch.float32` get converted into *"float32"* string, which can then be
-        stored in the json format.
+        Checks whether the passed dictionary and its nested dicts have a *torch_dtype* key and if it's not None,
+        converts torch.dtype to a string of just the type. For example, `torch.float32` get converted into *"float32"*
+        string, which can then be stored in the json format.
         """
         if d.get("torch_dtype", None) is not None and not isinstance(d["torch_dtype"], str):
             d["torch_dtype"] = str(d["torch_dtype"]).split(".")[1]
+        for value in d.values():
+            if isinstance(value, dict):
+                self.dict_torch_dtype_to_str(value)
 
     @classmethod
     def register_for_auto_class(cls, auto_class="AutoConfig"):