

TITLE
Mistake in the BART doc & inconsistency between code & doc

COMMENTS
3

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BODY
Version: Most recent in the Github repo.
Model: BART.

Description:
https://github.com/huggingface/transformers/blob/main/src/transformers/models/bart/modeling_bart.py#L627 says to look at `modeling_bart._prepare_decoder_inputs` to modify the default behavior of the way `decoder_attention_mask` behaves by default, but there is no `_prepare_decoder_inputs` anywhere in the Huggingface Transformers repository. I guess it's an artifact from a previous version, and that the function is now called `_prepare_decoder_attention_mask`. However, this method doesn't seem to look at the values of the decoder inputs anywhere, so I don't think it does what the doc says, ie mask the pad tokens. Or is this done somewhere else?

Thanks.


### Who can help?

@patil-suraj

### Expected behavior

```shell
Mask pad tokens by default in the decoder.
```
