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Date:   Fri, 16 Dec 2022 23:15:11 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     Wedson Almeida Filho <wedsonaf@gmail.com>
Cc:     Wei Liu <wei.liu@kernel.org>, rust-for-linux@vger.kernel.org,
        Linux Kernel List <linux-kernel@vger.kernel.org>,
        Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>
Subject: Re: [PATCH] rust: kernel: drop repetition in offset_of macro
Message-ID: <Y5z7/9OVzZd1ols1@liuwe-devbox-debian-v2>
References: <20221216174927.1008629-1-wei.liu@kernel.org>
 <CANeycqo2qKUnyh6XVkBHyAcVjvN9NKJ9sb9bTzkHq7jC1C-B0w@mail.gmail.com>
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On Fri, Dec 16, 2022 at 06:26:57PM +0000, Wedson Almeida Filho wrote:
> On Fri, 16 Dec 2022 at 17:49, Wei Liu <wei.liu@kernel.org> wrote:
> >
> > It doesn't make sense to allow multiple fields to be specified in
> > offset_of.
> 
> Why do you say it doesn't make sense?
> 
> Here's what I had in mind:
> ```
>     struct Y {
>         z: u32
>     }
>     struct X {
>         y: Y
>     }
>     offset_of!(X, y.z)
> ```
> 
> Which is something very plausible.
> 
> > No functional change.
> >
> > Signed-off-by: Wei Liu <wei.liu@kernel.org>
> > ---
> > Cc: Miguel Ojeda <ojeda@kernel.org>
> > Cc: Alex Gaynor <alex.gaynor@gmail.com>
> > Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
> > Cc: Boqun Feng <boqun.feng@gmail.com>
> > Cc: Gary Guo <gary@garyguo.net>
> > Cc: Bj?rn Roy Baron <bjorn3_gh@protonmail.com>
> > ---
> >  rust/kernel/lib.rs | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> > index 6a322effa60c..2f3601e4e27e 100644
> > --- a/rust/kernel/lib.rs
> > +++ b/rust/kernel/lib.rs
> > @@ -208,7 +208,7 @@ impl<'a> Drop for KParamGuard<'a> {
> >  /// ```
> >  #[macro_export]
> >  macro_rules! offset_of {
> > -    ($type:ty, $($f:tt)*) => {{

Shouldn't this be + instead of *?

offset_of!(X,) is valid according to this pattern.

Thanks,
Wei.