Re:Writing into Uninitialized Buffers in Rust
by Arnavion on Wednesday May 21, 2025 @02:33AM
(#44048849)
As I wrote in https://news.ycombinator.com/item?id=44048391 , you have to get used to copying the libstd impl when working with MaybeUninit. For my code I put a "TODO(rustup)" comment on such copies, to remind myself to revisit them every time I update the Rust version in toolchain.toml
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Re:Writing into Uninitialized Buffers in Rust
by nemothekid on Wednesday May 21, 2025 @04:11AM
(#44049347)
In other words the """safe""" stable code looks like this:
let mut data = Vec::with_capacity(sz);
let mut dst_uninit = data.spare_capacity_mut();
let uninit_src: &[MaybeUninit<T>] = unsafe { transmute(buf) };
dst_uninit.copy_from_slice(uninit_src);
unsafe { data.set_len(sz) };