Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Referencing NULL pointers
Message-ID: <10862@smoke.BRL.MIL>
Date: 28 Aug 89 20:37:50 GMT
References: <32UP02Eg3d=801@amdahl.uts.amdahl.com> <1382@bruce.OZ> <10830@smoke.BRL.MIL> <9838@xanth.cs.odu.edu>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 10

In article <9838@xanth.cs.odu.edu> kremer@cs.odu.edu (Lloyd Kremer) writes:
>	p = 0;  /* integer variable that happens to be set to zero */
>	data = *(int *)p;  /* no constant expression in this line */
>I would think the "promotion to nil pointer" rule would not apply here.

Correct, as Chris has already pointed out.  However I think there are
enough requirements imposed on converting between integers and pointers
that if you allow the above you'll also have to make the null pointer a
funny bit pattern, with resulting higher overhead than most people would
think necessary in that environment.  I don't have a formal proof though..