Restructure torch/torch.h and extension.h (#13482)
Summary:
This PR restructures the public-facing C++ headers in a backwards compatible way. The problem right now is that the C++ extension header `torch/extension.h` does not include the C++ frontend headers from `torch/torch.h`. However, those C++ frontend headers can be convenient. Further, including the C++ frontend main header `torch/torch.h` in a C++ extension currently raises a warning because we want to move people away from exclusively including `torch/torch.h` in extensions (which was the correct thing 6 months ago), since that *used* to be the main C++ extension header but is now the main C++ frontend header. In short: it should be possible to include the C++ frontend functionality from `torch/torch.h`, but without including that header directly because it's deprecated for extensions.
For clarification: why is `torch/torch.h` deprecated for extensions? Because for extensions we need to include Python stuff, but for the C++ frontend we don't want this Python stuff. For now the python stuff is included in `torch/torch.h` whenever the header is used from a C++ extension (enabled by a macro passed by `cpp_extensions.py`) to not break existing users, but this should change in the future.
The overall fix is simple:
1. C++ frontend sub-headers move from `torch/torch.h` into `torch/all.h`.
2. `torch/all.h` is included in:
1. `torch/torch.h`, as is.
2. `torch/extensions.h`, to now also give C++ extension users this functionality.
With the next release we can then:
1. Remove the Python includes from `torch/torch.h`
2. Move C++-only sub-headers from `all.h` back into `torch.h`
3. Make `extension.h` include `torch.h` and `Python.h`
This will then break old C++ extensions that include `torch/torch.h`, since the correct header for C++ extensions is `torch/extension.h`.
I've also gone ahead and deprecated `torch::CPU` et al. since those are long due to die.
ezyang soumith apaszke fmassa
Pull Request resolved: https://github.com/pytorch/pytorch/pull/13482
Differential Revision: D12924999
Pulled By: goldsborough
fbshipit-source-id: 5bb7bdc005fcb7b525195b769065176514efad8a
diff --git a/torch/extension.h b/torch/extension.h
index 828aefd..0ff1425 100644
--- a/torch/extension.h
+++ b/torch/extension.h
@@ -1,6 +1,8 @@
#pragma once
-#include <Python.h>
-
-#include <torch/csrc/utils/pybind.h>
+// All pure C++ headers for the C++ frontend.
+#include <torch/all.h>
+// Python bindings for the C++ frontend (includes Python.h).
+#include <torch/python.h>
+// Deprecated tensor factories (to be removed).
#include <torch/csrc/variable_tensor_functions.h>
