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From:   Alice Ryhl <aliceryhl@google.com>
Date:   Wed, 25 Oct 2023 15:29:56 +0200
Message-ID: <CAH5fLgiT4A1jMcsUhPdnXZC0cd=GMWuwDmLjnAGxe55+9HBiJA@mail.gmail.com>
Subject: Re: [PATCH v2] rust: macros: improve `#[vtable]` documentation
To:     Benno Lossin <benno.lossin@proton.me>
Cc:     Alice Ryhl <alice@ryhl.io>, Boqun Feng <boqun.feng@gmail.com>,
        Gary Guo <gary@garyguo.net>,
        =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>,
        Andreas Hindborg <nmi@metaspace.dk>,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        Miguel Ojeda <ojeda@kernel.org>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Alex Gaynor <alex.gaynor@gmail.com>
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On Mon, Oct 23, 2023 at 9:01=E2=80=AFAM Benno Lossin <benno.lossin@proton.m=
e> wrote:
>
> On 21.10.23 14:45, Alice Ryhl wrote:
> > On 10/19/23 19:15, Benno Lossin wrote:
> >> Traits marked with `#[vtable]` need to provide default implementations
> >> for optional functions. The C side represents these with `NULL` in the
> >> vtable, so the default functions are never actually called. We do not
> >> want to replicate the default behavior from C in Rust, because that is
> >> not maintainable. Therefore we should use `build_error` in those defau=
lt
> >> implementations. The error message for that is provided at
> >> `kernel::error::VTABLE_DEFAULT_ERROR`.
> >>
> >> Signed-off-by: Benno Lossin <benno.lossin@proton.me>
> >
> > Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> >
> > There is a minor nit below, and in reviews sent by others, but overall
> > this looks fine to me.
> >
> >>    /// # Examples
> >>    ///
> >>    /// ```ignore
> >> +/// # use kernel::error::VTABLE_DEFAULT_ERROR;
> >>    /// use kernel::prelude::*;
> > I probably wouldn't hide the import of VTABLE_DEFAULT_ERROR from this
> > example.
>
> What do you guys think of putting the const it in the prelude?

I think it's fine to just import it.

Alice