PySlice::new converts isize to c_long which is incorrect on Windows

[Narsil]

Bug Description

When trying to take a large slice with PySlice::new(start, stop, step) one, can overflow and get back an erroneous answer on Windows platform.

Core of the issue seems to be here:

https://docs.rs/pyo3/latest/src/pyo3/types/slice.rs.html#43-52

https://doc.rust-lang.org/stable/std/ffi/type.c_long.html Which is said to be i32 on Windows platform.

It seems using c_longlong https://doc.rust-lang.org/stable/std/ffi/type.c_longlong.html should fix the issue along with pyo3::ffi::PyLong_FromLongLong(start as std::ffi::c_longlong) which are defined to be at least i64 on most systems (including Windows x64bit where isize is i64 and c_long is not, which is the core of this issue)

Steps to Reproduce

Create a slice with either value being over i32::MAX. (it will silently overflow to negative values).

Backtrace

No response

Your operating system and version

Windows (any afaik)

Your Python version (python --version)

Any (afaik)

Your Rust version (rustc --version)

1.65 (but any)

Your PyO3 version

0.17.2

How did you install python? Did you use a virtualenv?

pyenv but all are affected afaik

Additional Info

Original report: huggingface/safetensors#95

Temporary fix in the lib itself huggingface/safetensors#99

Happy to contribute a PR if wanted.

@davidhewitt for visibility.

[birkenfeld]

PyLong_FromSsize_t should be used; isize is what Python calls Py_ssize_t.