tokenization_bart.py: return_tensors default should be "pt"

[Mehrad0711]

return_tensors default should be "pt" in bart's prepare_seq2seq_batch.

[thomwolf]

Tokenizers are supposed to be framework (PyTorch/TensorFlow/FLAX) agnostic so we probably don't want to do in that direction.

[Mehrad0711]

Gotcha. Is this going to be the case for all tokenizers in the future? Because currently they default to PyTorch except for Bart's.
Also, I think the docstring for Bart tokenizer's return_tensors needs to be updated then since it says: optional, defaults to "pt"

[LysandreJik]

The fact that the BART-like tokenizers have return_tensors="pt" is a mistake. The tokenizers should be framework-agnostic.

[LysandreJik]

We will have to update this, which will be a breaking change, so we'll try to put it in the v4.0.0. Do you want to open a PR to fix the issue?

[Mehrad0711]

Sure. I'll close this then and make a new PR for that.

[LysandreJik]

Hi @Mehrad0711! We're rushing to [email protected], and we don't want that in this release. I've taken the liberty of fixing it in #8599. Sorry about that, I hope you had not started your development.

If you have, you can push your fixes and open a PR and I'll incorporate those changes in my PR and mark you as co-author.

[Mehrad0711]

No problem @LysandreJik . Thanks for fixing it!