linux-kernel - Re: [PATCH v1 4/4] auxdisplay: lcd2s: Use array size explicitly in lcd2s

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Date:   Thu, 24 Mar 2022 11:21:25 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Cc:     Miguel Ojeda <ojeda@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 4/4] auxdisplay: lcd2s: Use array size explicitly in
 lcd2s_gotoxy()

On Wed, Mar 23, 2022 at 08:15:57PM +0100, Miguel Ojeda wrote:
> On Sat, Mar 19, 2022 at 12:37 PM Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
> >
> > With [] and parameters not being bytes by type one needs an additional
> > processing step to figure that out. When I see u8 ...[3] I immediately
> > understand that there are 3 _bytes_. Moreover, [] is error prone when
> > one may add something to the buffer with the expectation that it will
> > work somehow (for example, with an old device you need 3, with new
> > device revision you need 4 bytes and passing 4 bytes breaks the old
> > device). Of course most of that quite likely won't happen.
> 
> I agree it is better to be explicit -- I just found the commit message
> very confusing, i.e. the type will always be `u8`, what is unclear is
> the total length, not so much the type change.
> 
> I think the best approach when one needs an array to stay a particular
> size due to some external constraint (like hardware) would be to use a
> `static_assert` with a comment mentioning where the requirement comes
> from. Or at least a comment above the array.
> 
> Either way, I applied this one too to -next a few days ago. Thanks!

Thanks!

-- 
With Best Regards,
Andy Shevchenko