how about sizeof(((type *)1)->member) ?

[Richard O'Keefe]

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?