Xref: utzoo news.software.b:3614 comp.unix.microport:3850
Path: utzoo!attcan!uunet!samsung!brutus.cs.uiuc.edu!rpi!crdgw1!crdos1!davidsen
From: davidsen@crdos1.crd.ge.COM (Wm E Davidsen Jr)
Newsgroups: news.software.b,comp.unix.microport
Subject: Re: Cnews on System V/AT: "expression causes compiler loop"
Message-ID: <1676@crdos1.crd.ge.COM>
Date: 21 Nov 89 14:25:39 GMT
References: <3056@splut.conmicro.com> <1989Nov20.181839.1546@utzoo.uucp>
Reply-To: davidsen@crdos1.UUCP (bill davidsen)
Followup-To: news.software.b
Organization: GE Corp R&D Center, Schenectady NY
Lines: 24

In article <1989Nov20.181839.1546@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes:
| The offsetof() macro has a tendency to stress-test compilers.  Try:
| 
| #define offsetof(type, mem) ((int)&((type *)NULL)->mem)
| 
| as an alternative.

  I would be very careful using this. Althoug I feel that the use of a
zero cast to a non-void type is legal in sizeof, because of qualifying
statements promising that it is not evaluated, I would not be surprized
to see a compiler reject this one.

  I see how it works, I realize that it will work on many compilers, but
I am suspicious that it is not really portable. I would put the
definition in ifdefs at the very least, so that the required offsetof
macro could be used on undamaged compilers.

  The error message reminds me of things I used to get out of MSC some
years ago.
-- 
bill davidsen	(davidsen@crdos1.crd.GE.COM -or- uunet!crdgw1!crdos1!davidsen)
"The world is filled with fools. They blindly follow their so-called
'reason' in the face of the church and common sense. Any fool can see
that the world is flat!" - anon