linux-kernel - Re: [PATCH v2 1/2] asus-wmi: Adjust tablet/lidflip handling to use enum

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Date:   Mon, 8 Aug 2022 19:18:08 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     "Luke D. Jones" <luke@...nes.dev>,
        Mark Gross <markgross@...nel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] asus-wmi: Adjust tablet/lidflip handling to use
 enum

Hi,

On 8/8/22 18:24, Andy Shevchenko wrote:
> On Mon, Aug 8, 2022 at 6:13 PM Hans de Goede <hdegoede@...hat.com> wrote:
>> On 8/8/22 17:48, Andy Shevchenko wrote:
>>> On Mon, Aug 8, 2022 at 5:12 AM Luke D. Jones <luke@...nes.dev> wrote:
> 
> ...
> 
>>> To the switch-cases, please add a "default" case to each of them.
>>
>> The switch-cases are on an enum type, so adding a default is
>> not necessary and adding one will actually loose the useful
>> compiler warning about unhandled enum values.
> 
> It's good if you can cover all enum values, which usually you can't.
> enum according to the standard should be located in the type that is
> enough to keep it and be compatible to a char. This means that the
> code somewhere else may assign anything to enum (actually enum values
> are type of int) and without default you can't see the difference here
> and the compiler probably will be happy. That said, I doubt the
> usefulness of such a warning. But it's up to you.

I would prefer to not introduce a default label in this case; in
the unexpected case that the value gets set out of the enum range
then the switch-case will be a no-op and any added default would
also be a no-op, so adding a default gains us nothing.

Regards,

Hans