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From: Peter Zijlstra <peterz@infradead.org>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-toolchains@vger.kernel.org, Michael Matz <matz@suse.de>,
	Richard Biener <rguenther@suse.de>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: older gccs and case labels producing integer constants
Date: Tue, 5 Apr 2022 14:23:31 +0200	[thread overview]
Message-ID: <Ykw0wzdab0ICUFvy@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YkwQ6+tIH8GQpuct@zn.tnic>

On Tue, Apr 05, 2022 at 11:50:35AM +0200, Borislav Petkov wrote:
> Hi folks,
> 
> I'm starting to see failures like this on allmodconfig builds:
> 
> sound/usb/midi.c: In function ‘snd_usbmidi_out_endpoint_create’:
> sound/usb/midi.c:1389:2: error: case label does not reduce to an integer constant
>   case (((0xfc08) << 16) | (0x0101)):
>   ^~~~
> 
> (The case statement is a macro but it evaluates to what I have there)
> 
> and that thing fails with
> 
> $ gcc --version
> gcc (SUSE Linux) 7.5.0
> 
> although it doesn't have any problems building with newer compilers.
> 
> I'm presuming older gccs consider those case statements signed ints and
> the following fixes it:
> 
>   case ((((unsigned int)0xfc08) << 16) | (0x0101)):
> 
> and I guess we can whack the couple of occurrences but what I'm
> wondering is why does this work with newer gccs?

IIRC GCC-8 fixed a bunch of -wrapv issues. Could be this is one of them
I suppose.

  parent reply	other threads:[~2022-04-05 14:59 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-05  9:50 older gccs and case labels producing integer constants Borislav Petkov
2022-04-05  9:58 ` Richard Biener
2022-04-05 10:04   ` Borislav Petkov
2022-04-05 10:06   ` Richard Biener
2022-04-05 10:36     ` Borislav Petkov
2022-04-05 10:45       ` Borislav Petkov
2022-04-05 11:41         ` Richard Biener
2022-04-07 15:16           ` Borislav Petkov
2022-04-05 11:37       ` Richard Biener
2022-04-06  9:53       ` Jakub Jelinek
2022-04-06 10:04         ` Jakub Jelinek
2022-04-05 12:23 ` Peter Zijlstra [this message]
2022-04-05 12:39   ` Michael Matz
2022-04-05 12:53     ` Richard Biener
2022-04-05 13:04       ` Borislav Petkov
2022-04-06 10:13   ` Jakub Jelinek

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