linux-kernel - Re: [PATCH v2 1/2] rust: macros: Add derive Display for enums

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <DFGJ8UBULO54.NRW84R2DTHIK@kernel.org>
Date: Mon, 05 Jan 2026 10:02:59 +0100
From: "Benno Lossin" <lossin@...nel.org>
To: "Maurice Hieronymus" <mhi@...lbox.org>, <dakr@...nel.org>
Cc: <aliceryhl@...gle.com>, <acourbot@...dia.com>, <airlied@...il.com>,
 <simona@...ll.ch>, <nouveau@...ts.freedesktop.org>,
 <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
 <ojeda@...nel.org>, <boqun.feng@...il.com>, <gary@...yguo.net>,
 <bjorn3_gh@...tonmail.com>, <a.hindborg@...nel.org>, <tmgross@...ch.edu>,
 <rust-for-linux@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] rust: macros: Add derive Display for enums

On Sun Jan 4, 2026 at 9:07 PM CET, Maurice Hieronymus wrote:
> Add a derive macro that implements kernel::fmt::Display for enums.
> The macro outputs the exact variant name as written, preserving case.
>
> This supports all enum variant types: unit, tuple, and struct variants.
> For variants with data, only the variant name is displayed.

I don't think we should be adding this. Display is designed for
user-facing output and so it should always be carefully designed and no
automation should exist for it.

The use-case in the second patch is also much better served by either a
manual match on the enum:

    impl fmt::Display for Chipset {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            match self {
                Chipset::Variant => write!(f, "Variant"),
                // ...
            }
        }
    }

Or by adding the respective code in the declarative macro already used
to define it.

Cheers,
Benno

> Signed-off-by: Maurice Hieronymus <mhi@...lbox.org>
> ---
>  rust/macros/display.rs | 52 ++++++++++++++++++++++++++++++++++++++++++
>  rust/macros/lib.rs     | 42 ++++++++++++++++++++++++++++++++++
>  2 files changed, 94 insertions(+)
>  create mode 100644 rust/macros/display.rs