linux-kernel - Re: [RFC PATCH 1/9] kernel.h: add do

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Message-ID: <144825af-536e-9f11-f055-7ff978ede505@infradead.org>
Date:   Sat, 18 Apr 2020 15:24:33 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Bart Van Assche <bvanassche@....org>, linux-kernel@...r.kernel.org
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org, Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Chuck Lever <chuck.lever@...cle.com>,
        linux-nfs@...r.kernel.org,
        Johannes Berg <johannes@...solutions.net>,
        Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>, linux-nvdimm@...ts.01.org,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org, target-devel@...r.kernel.org,
        Zzy Wysm <zzy@...wysm.com>
Subject: Re: [RFC PATCH 1/9] kernel.h: add do_empty() macro

On 4/18/20 3:20 PM, Bart Van Assche wrote:
> On 4/18/20 11:41 AM, Randy Dunlap wrote:
>> --- linux-next-20200327.orig/include/linux/kernel.h
>> +++ linux-next-20200327/include/linux/kernel.h
>> @@ -40,6 +40,14 @@
>>   #define READ            0
>>   #define WRITE            1
>>   +/*
>> + * When using -Wextra, an "if" statement followed by an empty block
>> + * (containing only a ';'), produces a warning from gcc:
>> + * warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
>> + * Replace the empty body with do_empty() to silence this warning.
>> + */
>> +#define do_empty()        do { } while (0)
>> +
>>   /**
>>    * ARRAY_SIZE - get the number of elements in array @arr
>>    * @arr: array to be sized
> 
> I'm less than enthusiast about introducing a new macro to suppress "empty body" warnings. Anyone who encounters code in which this macro is used will have to look up the definition of this macro to learn what it does. Has it been considered to suppress empty body warnings by changing the empty bodies from ";" into "{}"?

I mentioned that possibility in PATCH 0/9 (cover letter)...
which should have been RFC PATCH 0/9.
So yes, it is possible.

You are the only other person who has mentioned it.

thanks.
-- 
~Randy