Quick fix to make torch.tensor work with functorch (#62423)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62423
Fixes https://github.com/facebookresearch/functorch/issues/7.
functorch uses FuncTorchDynamicLayerBackMode as a mode key to wrap all
tensors returned from operators in special TensorWrapper tensor
extension.
The problem with this is that TensorWrapper does not have storage so
accessing the data_ptr (for recursive_store) internal asserts.
As a quick hack, the guard added prevents functorch from wrapping the
empty tensor in a TensorWrapper and instead when `tensor.to` is called later,
the tensor gets wrapped. This is effectively what Ed proposed in
https://github.com/facebookresearch/functorch/issues/7#issuecomment-847501020
In the long term we probably want some better way of extending
`internal_new_from_data` for cases like this (where there is a
mode-based dispatch key for a C++ tensor extension -- the Python case
may be different).
Test Plan: - Verified that this fixes functorch's problem
Reviewed By: malfet
Differential Revision: D29992607
Pulled By: zou3519
fbshipit-source-id: 82b713156a37d7470f8fc46e3803ee7353689a33
