Make it illegal to directly construct _TensorBase (#56150)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56150
See #56017 for full context; the short story is that by making
it illegal to directly construct _TensorBase, we need only
write a *single* tp_dealloc function which will work universally
for all _TensorBase subclasses, rather than having to write two
versions, one for _TensorBase itself, and others for Python subclasses
of _TensorBase. This means simpler code.
The subtlety here is that we only install our custom `tp_new` for direct subclasses of TensorBase. This is important, because overriding the `tp_new` also overrides any user defined constructor. Fortunately class Tensor(_TensorBase) has no nontrivial constructors and doesn't mind, but other subclasses like Parameter definitely mind!
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Reviewed By: H-Huang
Differential Revision: D28028746
Pulled By: ezyang
fbshipit-source-id: 3c03a14666ad1ded1145fe676afb0a7623cdb9bb
