RFC-0010: TensorRef

[ezyang]

This proposal introduces a new class TensorRef, to replace all places in our codebase where we currently use const Tensor&. The distinguishing characteristics of this class are:

1. It is non-owning
2. It is as safe as other by-value reference types (like c10::ArrayRef or std::string_view)
3. It is implicitly convertible (with some exceptions) to const Tensor& (i.e., it can be introduced incrementally)

Rendered

Signed-off-by: Edward Z. Yang [email protected]

[ezyang]

A variation of this has been implemented in https://github.com/pytorch/pytorch/pull/55685

[swolchok]

A variation of this has been implemented in pytorch/pytorch#55685

As with the TensorRef in the proposal, MaybeOwned is hobbled by the Itanium ABI requirement to pass it by reference always, so it doesn't solve the argument passing problem either.