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Partially stabilize const_slice_from_raw_parts by xfix · Pull Request #97522 · r...

 2 years ago
source link: https://github.com/rust-lang/rust/pull/97522
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@xfix xfix commented on May 29 •

edited

This doesn't stabilize methods working on mutable pointers.

This pull request continues from #94946.

Pinging @rust-lang/wg-const-eval this because I use rustc_allow_const_fn_unstable. I believe this is justifiable as it's already possible to use slice::from_raw_parts in stable by abusing transmute. The stable alternative to this would be to provide a stable const implementation of std::ptr::from_raw_parts (as it can already be implemented in stable).

use std::mem;

#[repr(C)]
struct Slice<T> {
    data: *const T,
    len: usize,
}

fn main() {
    let data: *const i32 = [1, 2, 3, 4].as_ptr();
    let len = 4;
    println!("{:?}", unsafe {
        mem::transmute::<Slice<i32>, &[i32]>(Slice { data, len })
    });
}

@rustbot modify labels: +T-libs-api

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