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Date:      Sat, 21 Jul 2012 16:00:45 -0400
From:      Kim Culhan <w8hdkim@gmail.com>
To:        Dimitry Andric <dim@freebsd.org>
Cc:        freebsd-current@freebsd.org
Subject:   Re: -current build failure
Message-ID:  <CAKZxVQXC6DuX5UTn3goNM9toxSVkP8-7bazTk%2Ba7yLEy7RsJYA@mail.gmail.com>
In-Reply-To: <50097BF0.9010103@FreeBSD.org>
References:  <CAKZxVQV5xhFDN_WbTk-EMoQ18N8u1f4YhqKSJQFUzbX4NZxhUA@mail.gmail.com> <50097BF0.9010103@FreeBSD.org>

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On Fri, Jul 20, 2012 at 11:40 AM, Dimitry Andric <dim@freebsd.org> wrote:
> On 2012-07-20 16:49, Kim Culhan wrote:
>>  Seeing this for r:238655
> ...
>> In file included from /usr/src/sys/modules/dtrace/dtrace/../../../sys/pcpu.h:44:
>> ./machine/pcpu.h:226:13: error: indirection of non-volatile null
>> pointer will be deleted, not trap
>>       [-Werror,-Wnull-dereference]
>>             : "m" (*(char *)OFFSETOF_CURTHREAD));
>>                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>> ./machine/pcpu.h:226:13: note: consider using __builtin_trap() or
>> qualifying pointer with 'volatile'
>
> That's indeed a valid warning from clang, since OFFSETOF_CURTHREAD is
> usually zero.  It's probably due to recent work on dtrace.  I'm not in
> the neighborhood of a FreeBSD box right now to verify, but can you
> please try to change the cast to "(volatile char *)"?  That should fix
> the warning.

Yes it did, I know there are many considerations wrt to this warning.

thanks
-kim



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