Announcing Rust 1.70.0

[cuviper]

No description provided.

[cuviper]

This definitely needs more work, but a PR will let others start chipping in.

[scottmcm]

It looks like this didn't get a milestone, somehow, but I think rust-lang/rust#98112 landed in this release? We know that there's UB code in the wild that trips those checks (rust-lang/rust#111487), so might be worth a mention here.

A placeholder example, please change as desired:

#[repr(align(8))]
struct AlignedArray([u8; 8]);
let a = AlignedArray([0; 8]);
// This dereference is definitely under-aligned, and thus UB
let s = unsafe { *a.0.as_ptr().add(1).cast::<f32>() };
dbg!(s);

https://play.rust-lang.org/?version=beta&mode=debug&edition=2021&gist=b20e8bb0b0cd066b1da9fcbcf8e0b252

thread 'main' panicked at 'misaligned pointer dereference: address must be a multiple of 0x4 but is 0x7ffc6af764e9', src/main.rs:6:22

[cuviper]

It looks like this didn't get a milestone, somehow, but I think rust-lang/rust#98112 landed in this release? We know that there's UB code in the wild that trips those checks (rust-lang/rust#111487), so might be worth a mention here.

That is in the full release notes, "Insert alignment checks for pointer dereferences as debug assertions" under compatibility. I'm not sure it's worth highlighting more than that, but I could be convinced...