offsetof

[John F Carr]

Two questions about offsetof.

1. Is the following legal?

	struct foo { struct bar { int b;} a;};
	offsetof (struct foo, a.b);

The X toolkit source code assumes that offsetof (struct foo, a.b) is legal.
The compiler I use disagrees.  I think it is right, but I'm not sure.

2. On how many compilers does the following trick to emulate offsetof not work:
	(int)&((struct foo*)0)->member

How many of those do not provide an offsetof macro?

(I know of only one compiler which doesn't like the version using a NULL
pointer (Metaware High C 1.4r for the IBM RT), and that compiler provides
an offsetof macro).

 
--
    John Carr (jfc at athena.mit.edu)