sizeof a struc field

[Doug Gwyn]

In article <8361 at ardent.UUCP> jss at jra.ardent.com (Jerry Schwarz (Compiler)) writes:
-With regard to a discussion of:
-	sizeof(((struct abc *)0)->ghi)
-Which suggests that Doug believes that this is an illegal expression.  
-But is it?  It (the operand of sizeof) is an expression whose evaluation 
-would result in undefined behavior, but does that make it illegal? 
-I think not, and here it is used in a context where it explicitly will 
-not be evaluated.

(((struct abc *)0)->ghi) is not a valid unary expression,
because the left-hand operand of the -> is not an lvalue
that points at an object (see 3.3.2.3 Semantics).

This has nothing to do with evaluation.