Warn for unexpected argument combinations (#13509)

* Warn for unexpected argument combinations

* Updated the waning message for pad_to_max_length

src/transformers/tokenization_utils_base.py

@@ -2222,6 +2222,11 @@ class PreTrainedTokenizerBase(SpecialTokensMixin, PushToHubMixin):
                 padding_strategy = PaddingStrategy.MAX_LENGTH
         elif padding is not False:
             if padding is True:
+                if verbose:
+                    if max_length is not None:
+                        warnings.warn("`max_length` is ignored when `padding`=`True`.")
+                    if old_pad_to_max_length is not False:
+                        warnings.warn("Though `pad_to_max_length` = `True`, it is ignored because `padding`=`True`.")
                 padding_strategy = PaddingStrategy.LONGEST  # Default to pad to the longest sequence in the batch
             elif not isinstance(padding, PaddingStrategy):
                 padding_strategy = PaddingStrategy(padding)