linux-kernel - Re: [PATCH v4 2/4] rust: macros: add derive macro for `TryFrom`

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 for Android: free password hash cracker in your pocket

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

Message-Id: <DF7HEMI7I3LS.FW1IPV2QS2HB@kernel.org>
Date: Thu, 25 Dec 2025 18:42:31 +0100
From: "Benno Lossin" <lossin@...nel.org>
To: <y.j3ms.n@...il.com>, "Miguel Ojeda" <ojeda@...nel.org>, "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>, "Danilo Krummrich" <dakr@...nel.org>,
 "Alexandre Courbot" <acourbot@...dia.com>
Cc: <linux-kernel@...r.kernel.org>, <rust-for-linux@...r.kernel.org>,
 <nouveau@...ts.freedesktop.org>
Subject: Re: [PATCH v4 2/4] rust: macros: add derive macro for `TryFrom`

On Thu Dec 25, 2025 at 9:37 AM CET, Jesung Yang via B4 Relay wrote:
> +/// ## Compile-time Overflow Assertion
> +///
> +/// The following examples do not compile:
> +///
> +/// ```compile_fail
> +/// # use kernel::macros::Into;
> +/// #[derive(Into)]
> +/// #[into(u8)]
> +/// enum Foo {
> +///     // `256` is larger than `u8::MAX`.
> +///     A = 256,
> +/// }
> +/// ```
> +///
> +/// ```compile_fail
> +/// # use kernel::macros::Into;
> +/// #[derive(Into)]
> +/// #[into(u8)]
> +/// enum Foo {
> +///     // `-1` cannot be represented with `u8`.
> +///     A = -1,
> +/// }
> +/// ```

These two are copy-pasted from the `into` macro.

Cheers,
Benno

> +///
> +/// ## Unsupported Cases
> +///
> +/// The following examples do not compile:
> +///
> +/// ```compile_fail
> +/// # use kernel::macros::TryFrom;
> +/// // Tuple-like enums or struct-like enums are not allowed.
> +/// #[derive(TryFrom)]
> +/// enum Foo {
> +///     A(u8),
> +///     B { inner: u8 },
> +/// }
> +/// ```
> +///
> +/// ```compile_fail
> +/// # use kernel::macros::TryFrom;
> +/// // Structs are not allowed.
> +/// #[derive(TryFrom)]
> +/// struct Foo(u8);
> +/// ```
> +#[proc_macro_derive(TryFrom, attributes(try_from))]
> +pub fn derive_try_from(input: TokenStream) -> TokenStream {
> +    let input = parse_macro_input!(input as DeriveInput);
> +    convert::derive_try_from(input)
> +        .unwrap_or_else(syn::Error::into_compile_error)
> +        .into()
> +}