Re: [PATCH v2 00/19] `zerocopy` support

On Mon, Jun 8, 2026 at 4:15 PM Miguel Ojeda <[email protected]> wrote:
>
> This patch series introduces support for `zerocopy`:
>
>     Fast, safe, compile error. Pick two.
>
>     Zerocopy makes zero-cost memory manipulation effortless. We write
>     `unsafe` so you don't have to.
>
> It essentially provides derivable traits (e.g. `FromBytes`) and macros
> (e.g. `transmute!`) for safely converting between byte sequences and
> other types. Having such support allows us to remove some `unsafe` code.
>
> It is among the most downloaded Rust crates (top #50 recent, top #100
> all-time downloads; according to crates.io), and it is also used by the
> Rust compiler itself.
>
> The series starts with a few preparation commits, then the `zerocopy`
> and `zerocopy-derive` crates are added. Finally, an example patch using
> it is on top, removing one `unsafe impl`.
>
> I had to adapt the crates slightly (just +2/-3 lines), but both patches
> could potentially be provided upstream eventually. Please see the
> commits for details.
>
> In total, it is about ~39k lines added, ~32k without counting `benches/`
> which are just for documentation purposes.
>
> See the cover letter for `syn` for some more details about depending on
> third-party crates in commit 54e3eae85562 ("Merge patch series "`syn`
> support"").
>
> The codegen of an isolated example function similar to the patch on top
> is essentially identical. It also turns out that (for that particular
> case) `zerocopy`'s version, even under `debug-assertions` enabled, has
> no remaining panics, unlike a few in the current code (because the
> compiler can prove the remaining `ub_checks` statically).
>
> So their "fast, safe" does indeed check out -- at least in that case.
>
> P.S. This version of `zerocopy` has already the unstable `Ptr{,Inner}`
> types -- to play with them, please use:
>
>     make ... KRUSTFLAGS=--cfg=zerocopy_unstable_ptr
>
> ---
> I will apply v2 for tomorrow's linux-next.

Applied to `rust-next` (yesterday) -- thanks everyone!

Cheers,
Miguel