Migrate PyTorch to C++17 (#85969)
With CUDA-10.2 gone we can finally do it!
This PR mostly contains build system related changes, invasive functional ones are to be followed.
Among many expected tweaks to the build system, here are few unexpected ones:
- Force onnx_proto project to be updated to C++17 to avoid `duplicate symbols` error when compiled by gcc-7.5.0, as storage rule for `constexpr` changed in C++17, but gcc does not seem to follow it
- Do not use `std::apply` on CUDA but rely on the built-in variant, as it results in test failures when CUDA runtime picks host rather than device function when `std::apply` is invoked from CUDA code.
- `std::decay_t` -> `::std::decay_t` and `std::move`->`::std::move` as VC++ for some reason claims that `std` symbol is ambigious
- Disable use of `std::aligned_alloc` on Android, as its `libc++` does not implement it.
Some prerequisites:
- https://github.com/pytorch/pytorch/pull/89297
- https://github.com/pytorch/pytorch/pull/89605
- https://github.com/pytorch/pytorch/pull/90228
- https://github.com/pytorch/pytorch/pull/90389
- https://github.com/pytorch/pytorch/pull/90379
- https://github.com/pytorch/pytorch/pull/89570
- https://github.com/facebookincubator/gloo/pull/336
- https://github.com/facebookincubator/gloo/pull/343
- https://github.com/pytorch/builder/commit/919676fb32fa751f1589d95e0d3b76489d942d80
Fixes https://github.com/pytorch/pytorch/issues/56055
Pull Request resolved: https://github.com/pytorch/pytorch/pull/85969
Approved by: https://github.com/ezyang, https://github.com/kulinseth
