[clisp-list] ffi:c-var-address

[Andras S. <an...@re...>]

Can someone explain to me why the following works?

(with-c-var 
	  (struct '(c-struct list
		    (:string c-pointer)
		    (:icon c-pointer)
		    (:boolean boolean)
		    (:int int)
		    (:long long)
		    (:date single-float)
		    (:float single-float)
		    (:double double-float))
		  (list nil nil nil 0 0 (coerce 0 'single-float) (coerce 0 'single-float)
(coerce 0 'double-float)))
	(gtk-tree-model-get model iter col
			    (c-var-address (slot struct col-type))
			    -1)
...)

What I'm confused about is that (slot struct col-type) is not necessarily a
pointer (ie. a 'c-place') and yet c-var-address doesn't complain about it. 
(I see that c-var-address and slot are macros, but macroexpanding them 
results in a SIMPLE-SOURCE-PROGRAM-ERROR.)

Andras