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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Tue, 17 Jan 2023 21:05:58 +0100
Message-ID: <CAMuHMdWpHSsAB3WosyCVgS6+t4pU35Xfj3tjmdCDoyS2QkS7iw@mail.gmail.com>
Subject: Re: Calculating array sizes in C - was: Re: Build regressions/improvements
 in v6.2-rc1
To:     John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc:     linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org,
        linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org,
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        linux-xtensa@linux-xtensa.org,
        Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>,
        Arnd Bergmann <arnd@arndb.de>
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Hi Adrian,

On Tue, Jan 17, 2023 at 6:06 PM John Paul Adrian Glaubitz
<glaubitz@physik.fu-berlin.de> wrote:
> On 1/17/23 18:01, Geert Uytterhoeven wrote:
> > The issue is that some of the parameters are not arrays, but
> > NULL. E.g.:
> >
> > arch/sh/kernel/cpu/sh2/setup-sh7619.c:static
> > DECLARE_INTC_DESC(intc_desc, "sh7619", vectors, NULL,
> > arch/sh/kernel/cpu/sh2/setup-sh7619.c-                   NULL,
> > prio_registers, NULL);
>
> Isn't this supposed to be caught by this check:
>
>         a, __same_type(a, NULL)
>
> ?

Yeah, but gcc thinks it is smarter than us...
Probably it drops the test, assuming UB cannot happen.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds