anchor.diff:  
   ;; Expand arguments to function.
   (defun expex-argexpand-0 (ex fun args)
  +  (dolist (i args)
  +	(expex-warn i))
     (funcall (expex-function-collector ex) fun args)
     (let argdef (funcall (expex-function-arguments ex) fun)
   	(if (eq argdef 'builtin)
  
positive.code: ;;;;; assignments to temporary variables.
  
  (defvar *expex-funinfo* nil)
  
  ;;;; CONFIGURATION
  
  
negative.code: (defun expex-stack-locals? (ex)
    (and *expex-funinfo* ; Is set if we're inside a function.
  	   (transpiler-stack-locals? (expex-transpiler ex))))
  
  (defun expex-warn (x)
    (and *expex-warn?*
  	   (symbolp x)
  	   (not (or (functionp x)
  				(keywordp x)
  				(in? x nil t '~%ret 'this)
  	   			(funinfo-in-this-or-parent-env? *expex-funinfo* x)
  				(assoc x *variables*)
  	       		(expander-has-macro? (transpiler-std-macro-expander *current-transpiler*) x)
  		       	(expander-has-macro? (transpiler-macro-expander *current-transpiler*) x)))
  	   (warn "symbol ~A is not defined in function ~A.~%"
  			 (symbol-name x) (funinfo-get-name *expex-funinfo*))))
  
  ;;;; PREDICATES
  
  