linux-kernel - Re: [PATCH v4 4/7] rust: str: make `from_bytes_with_nul_unchecked

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Message-Id: <DAPYYWSUVMGN.L3ICDJAIJ2PO@kernel.org>
Date: Wed, 18 Jun 2025 23:16:26 +0200
From: "Benno Lossin" <lossin@...nel.org>
To: "Alexandre Courbot" <acourbot@...dia.com>, "Danilo Krummrich"
 <dakr@...nel.org>, "Miguel Ojeda" <ojeda@...nel.org>, "Alex Gaynor"
 <alex.gaynor@...il.com>, "Boqun Feng" <boqun.feng@...il.com>, "Gary Guo"
 <gary@...yguo.net>, Björn Roy Baron
 <bjorn3_gh@...tonmail.com>, "Andreas Hindborg" <a.hindborg@...nel.org>,
 "Alice Ryhl" <aliceryhl@...gle.com>, "Trevor Gross" <tmgross@...ch.edu>
Cc: <rust-for-linux@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 4/7] rust: str: make
 `from_bytes_with_nul_unchecked_mut` const

On Mon Jun 16, 2025 at 5:34 AM CEST, Alexandre Courbot wrote:
> This method was probably kept non-const due to the absence of the
> `const_mut_refs` feature, but it has been enabled since the introduction
> of this code (and stabilized with Rust 1.83). Thus, make it const to
> match its non-const counterpart.
>
> Signed-off-by: Alexandre Courbot <acourbot@...dia.com>

Ah on second thought, this and the next two patches are a bit redundant,
since Tamir has a series [1] removing our `CStr` and using the one from
`core`.

If you need this *now* and can't wait for Tamir's series to land, then
we can do this and the other two changes, but othrwise I'd just use
`CStr` from `core`.

It does seem like you need `&mut CStr`, which the one in `core` doesn't
seem to provide... But our `CStr` also doesn't have `IndexMut`, so...
how are you using it? Giving it to a C API?

In that case I don't know what we should do about [1]... @Miguel?

[1]: https://lore.kernel.org/all/20250530-cstr-core-v11-0-cd9c0cbcb902@gmail.com

---
Cheers,
Benno