SBCL

* (compile-file "/tmp/setf-test-1.lisp")

; compiling file "/tmp/setf-test-1.lisp" (written 14 JUL 2010 07:17:06 PM):
; compiling (DEFMACRO DEFINE-GLOBAL-SETF-EXPANDER ...)
; compiling (DEFPARAMETER *FOO* ...)
; compiling (DEFUN FOO-VAL ...)
; compiling (DEFUN (SETF FOO-VAL) ...)
; compiling (DEFINE-GLOBAL-SETF-EXPANDER FOO-VAL)
; compiling (DEFUN TEST ...)

; /tmp/setf-test-1.fasl written
; compilation finished in 0:00:00.228
#P"/tmp/setf-test-1.fasl"
NIL
NIL
* (load "/tmp/setf-test-1")
WARNING:
   defining setf macro for FOO-VAL when (SETF FOO-VAL) was previously treated as a function

T
* (setf (foo-val *foo*) 2)

2
*