[fix] `torch.broadcast_shapes` should not handle shapes with negative dimensions. (#72999)
Summary:
Hi,
The PR fixes https://github.com/pytorch/pytorch/issues/68957. It aims to include the following:
- Fixes the code in `torch/functional.py`.
- Add the missing tests for negative input values and non-iterable inputs.
~#### TODO~
~- [x] Add OpInfo~
EDIT: `broadcast_shapes` don't take any tensor inputs. So we don't need OpInfo here. Thanks, kshitij12345 for guidance.
#### Earlier
```python
>>> shapes = [1, -12]
>>> torch.broadcast_shapes(*shapes)
torch.Size([-12]) # MUST RAISE ERROR
```
#### Now
```python
>>> shapes = [1, -12]
>>> torch.broadcast_shapes(*shapes)
RuntimeError: Trying to create tensor with negative dimension -12: [-12]
```
#### NumPy's Output
```python
>>> shapes = [1, -12]
>>> numpy.broadcast_shapes(*shapes)
ValueError: negative dimensions are not allowed
```
#### `torch.broadcast_tensor()` Output
As mentioned in the [doc](https://pytorch.org/docs/stable/generated/torch.broadcast_shapes.html):
```python
>>> shapes = [1, -12]
>>> torch.broadcast_tensors(*map(torch.empty, shapes))[0].shape
RuntimeError: Trying to create tensor with negative dimension -12: [-12]
```
Looking forward to hearing from you and your questions. Thanks! :)
cc: mruberry kshitij12345
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72999
Reviewed By: albanD
Differential Revision: D34543995
Pulled By: ngimel
fbshipit-source-id: e32b1f266500a5e002c8f353b1e02f44c23d4f6e
(cherry picked from commit a6253ce6bb8455a3c89398f12b7d790a0b7e8d95)
