From mboxrd@z Thu Jan  1 00:00:00 1970
X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/2557
Path: news.gmane.org!not-for-mail
From: Bobby Bingham <uhmmmm@gmail.com>
Newsgroups: gmane.linux.lib.musl.general
Subject: Re: NULL
Date: Sat, 12 Jan 2013 01:07:46 -0600
Message-ID: <CAFNaaxQKNXK0MDV1n73AGFQGR6VZkx-Lvk7NCEuMyzFeazEG1A@mail.gmail.com>
References: <20130109153630.GZ20323@brightrain.aerifal.cx> <1357973768.32505.5@driftwood>
Reply-To: musl@lists.openwall.com
NNTP-Posting-Host: plane.gmane.org
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
X-Trace: ger.gmane.org 1357974504 14707 80.91.229.3 (12 Jan 2013 07:08:24 GMT)
X-Complaints-To: usenet@ger.gmane.org
NNTP-Posting-Date: Sat, 12 Jan 2013 07:08:24 +0000 (UTC)
To: musl@lists.openwall.com
Original-X-From: musl-return-2558-gllmg-musl=m.gmane.org@lists.openwall.com Sat Jan 12 08:08:42 2013
Return-path: <musl-return-2558-gllmg-musl=m.gmane.org@lists.openwall.com>
Envelope-to: gllmg-musl@plane.gmane.org
Original-Received: from mother.openwall.net ([195.42.179.200])
	by plane.gmane.org with smtp (Exim 4.69)
	(envelope-from <musl-return-2558-gllmg-musl=m.gmane.org@lists.openwall.com>)
	id 1TtvCp-0000m7-9t
	for gllmg-musl@plane.gmane.org; Sat, 12 Jan 2013 08:08:39 +0100
Original-Received: (qmail 30295 invoked by uid 550); 12 Jan 2013 07:08:21 -0000
Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm
Precedence: bulk
List-Post: <mailto:musl@lists.openwall.com>
List-Help: <mailto:musl-help@lists.openwall.com>
List-Unsubscribe: <mailto:musl-unsubscribe@lists.openwall.com>
List-Subscribe: <mailto:musl-subscribe@lists.openwall.com>
Original-Received: (qmail 30283 invoked from network); 12 Jan 2013 07:08:19 -0000
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=gmail.com; s=20120113;
        h=mime-version:in-reply-to:references:from:date:message-id:subject:to
         :content-type;
        bh=yljaPktLrqVOxsK4EjSuFNO4pRmcsA7WrlNP7vdtESg=;
        b=yM7JwdgyBPZev28qUyOkjQFhVDlkqxCsPi+gDUJCJ17htfUfhxF+OsWFHg3j7FMpVu
         MkY9mpk2PmxvLdHlQdbqVUyTeUGNIEUalPMPcr0TFGlIFfKhPjTxX55DBaavn930vNDV
         ZWlTRz79u37Hg73jdUWib8k17Ql8PKSp/IySPJ4y7fubZlcQH2SVCV8okFnQQx3zbaPb
         IrHOwocPZMkia+JqSnTu/V/vtJepc4Cc+qjZi9xATBFLpWrtg0AUe2uWqawbnr+u4MX9
         k90N7IMSPzbPxD2xL+G+bORT765xpoBUizBlwu3LNKglDomDszwHdyHEK+fKpvk7GfW6
         TRzw==
In-Reply-To: <1357973768.32505.5@driftwood>
Xref: news.gmane.org gmane.linux.lib.musl.general:2557
Archived-At: <http://permalink.gmane.org/gmane.linux.lib.musl.general/2557>

On Sat, Jan 12, 2013 at 12:56 AM, Rob Landley <rob@landley.net> wrote:
>> int null_is_ptr_type()
>> {
>>         char s[1][1+(int)NULL];
>>         int i = 0;
>>         return sizeof s[i++], i;
>> }
>
>
> (int)NULL is 0 according to C99 so the NULL in there has no effect. And
> referring to "i++" and "i" in the same statement is explicitly undefined
> behavior (comma is not a sequence point, the compiler is free to evaluate
> those in any order and different optimization flags _will_ change that
> order; I got bit by that many moons ago).
>

>From c99 section 6.5.17 Comma operator:
"The left operand of a comma operator is evaluated as a void
expression; there is a sequence point after its evaluation.  Then the
right operand is evaluated; the result has its type and value"

--
Bobby Bingham