linux-kernel - Re: [PATCH v1 2/2] tools/nolibc/stdio: Add format attribute to enable printf warnings

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Date:   Fri, 20 May 2022 06:21:45 +0200
From:   Willy Tarreau <w@....eu>
To:     Ammar Faizi <ammarfaizi2@...weeb.org>
Cc:     "Paul E. McKenney" <paulmck@...nel.org>,
        Alviro Iskandar Setiawan <alviro.iskandar@...weeb.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        GNU/Weeb Mailing List <gwml@...r.gnuweeb.org>,
        Facebook Kernel Team <kernel-team@...com>
Subject: Re: [PATCH v1 2/2] tools/nolibc/stdio: Add format attribute to
 enable printf warnings

On Fri, May 20, 2022 at 12:21:16AM +0700, Ammar Faizi wrote:
> From: Alviro Iskandar Setiawan <alviro.iskandar@...weeb.org>
> 
> When we use printf and fprintf functions from the nolibc, we don't
> get any warning from the compiler if we have the wrong arguments.
> For example, the following calls will compile silently:
> ```
>   printf("%s %s\n", "aaa");
>   fprintf(stdout, "%s %s\n", "xxx", 1);
> ```
> (Note the wrong arguments).
> 
> Those calls are undefined behavior. The compiler can help us warn
> about the above mistakes by adding a `printf` format attribute to
> those functions declaration.

I'm shocked I forgot it, I use it all the time, I'm even seeing this
as a bug fix for the series I sent. Thanks for fixing this mistake of
mine!

Acked-by: Willy Tarreau <w@....eu>

Willy