Show deprecation warning when stateful lambdas are used as kernels (#21885)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21885
If a kernel is defined as a stateful lambda
static auto registry = torch::RegisterOperators().op("my::op", [some_closure] (Tensor a) {...});
this can have very unexpected behavior when kernels are instantiated. There is no guarantee that the state is kept.
In the options based API, state is already disallowed:
// this is a compiler error
static auto registry = torch::RegisterOperators().op("my::op", torch::RegisterOperators::options().kernel([some_closure] (Tensor a) {...}));
but we can't disallow it in the non-options-based API for backwards compatibility reasons.
We can, however, show a deprecation warning. This is what this diff introduces.
Differential Revision: D15867089
fbshipit-source-id: 300fa4772fad8e7d177eb7cb910063d360537a4a
