Casting wide-pointers

8

Yeah, I did the same until I thought about it further. Maybe it will not be a practical problem ever, though.

But for now (as also said in the original thread), I prefer to rely on std::slice::from_raw_parts, I think. That is part of stable Rust:

fn trns(slice: &[u16]) -> &[u8] {
    let ptr = slice as *const [u16] as *const [u8];
    unsafe { &*ptr }
}

fn safer_trns(slice: &[u16]) -> &[u8] {
    unsafe {
        std::slice::from_raw_parts(
            slice as *const [u16] as *const u8,
            slice.len(),
        )
    }
}

fn useful_trns(slice: &[u16]) -> &[u8] {
    unsafe {
        std::slice::from_raw_parts(
            slice as *const [u16] as *const u8,
            std::mem::size_of_val(slice),
        )
    }
}

fn main() {
    let x = [1, 2, 3, 4, 5];
    let y1 = trns(&x);
    let y2 = safer_trns(&x);
    let y3 = useful_trns(&x);
    println!("{y1:?}");
    println!("{y2:?}");
    println!("{y3:?}");
}

(Playground)

Output:

[1, 0, 2, 0, 3]
[1, 0, 2, 0, 3]
[1, 0, 2, 0, 3, 0, 4, 0, 5, 0]