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From: ok@cs.mu.oz.au (Richard O'Keefe)
Newsgroups: comp.lang.c
Subject: Re: sizeof a struc field
Message-ID: <2488@munnari.oz.au>
Date: 21 Oct 89 10:04:28 GMT
References: <7710@microsoft.UUCP> <11316@smoke.BRL.MIL> <7685@cdis-1.uucp>
Sender: news@cs.mu.oz.au
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In article <7685@cdis-1.uucp>, tanner@cdis-1.uucp (Dr. T. Andrews) writes:
> What we have not heard is a convincing explanation of why the cited
> construct should be considered harmful.  No excuse for an
> implementation that might blow up on it has been given.  Further,
> no useful alternative has (to date) shown up.

I'm sure I'll be corrected if I'm wrong, but isn't the actual restriction
that the argument of "sizeof" must be an L-value in ANSI C?  If I'm right
about that, then the problem is not that sizeof ((struct foo*)NULL)->field
may "blow up", but that ((struct foo*)NULL)->field is not an L-value.