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From: ok@cs.mu.oz.au (Richard O'Keefe)
Newsgroups: comp.lang.c
Subject: Re: how about sizeof(((type *)1)->member) ?
Message-ID: <2582@munnari.oz.au>
Date: 30 Oct 89 03:26:51 GMT
References: <1989Oct27.141015.20578@talos.uucp> <2550111@hpisod2.HP.COM>
Sender: news@cs.mu.oz.au
Lines: 13

The problem is how to replace
	sizeof (((struct foo *)(0))->member)
in an ANSI-portable way.

Since malloc() must return a pointer which satisfies all alignment
requirements, could we not use

	#define fieldsize(Foo,Member) sizeof \
		(((struct Foo *)malloc(sizeof (struct Foo)))->Member)

Since the expression isn't going to be evaluated, nothing will be allocated.
If it _were_ evaluated, the expression would be valid, so a compiler has
nothing to complain about, or has it?