rust: updates for rust & clippy 1.54

[davidhewitt]

No description provided.

[davidhewitt]

Windows 32-bit segfault is because dictoffset in the PyCell seems to be calculated incorrectly. I think the types in pyclass_slots.rs need to be #[repr(C)], will confirm when I get home later

[davidhewitt]

Looks like we calculated dictoffset incorrectly on 32-bit windows. The dictoffset was resolving to the padding bytes at the end of the PyCell struct. I guess that Rust 1.54 might have stopped zero-initialising the padding (or vice versa?) which caused the crash to become noticeable.

I've replaced the offset calculations with more robust ones.

[birkenfeld]

Sounds like this should be released as 0.14.2?

[davidhewitt]

Yes, I'm going to open a PR to fix #1719 and then prepare the full lot as 0.14.2 release. (Hopefully today, depending on some family stuff I've got to do first)