Checking size attribute of dst when dst is None

[hrishikeshvganu]

In the code below if dst is None the dst.sizes[idx] block in Exception ... will throw an unhandled error.

This is around https://github.com/facebookresearch/fairseq-py/blob/master/fairseq/data.py#L222

for idx in indices:
        # - 2 here stems from make_positions() where we offset positions
        # by padding_value + 1
        if src.sizes[idx] < 2 or \
                (dst is not None and dst.sizes[idx] < 2) or \
                sizes[idx] > max_positions - 2:
            raise Exception("Unable to handle input id {} of "
                            "size {} / {}.".format(idx, src.sizes[idx], dst.sizes[idx]))

To fix this (dst is not None and dst.sizes[idx] < 2) can be modified to (False if dst is None else dst.sizes[idx] < 2)

[edunov]

Thank you @hrishikeshvganu for finding this. It is now fixed.