[Bug-openmcl] dynamic-extent in formatter macro

[bryan o'connor]

i don't understand dynamic-extent and its effect on the compiler.  so
with that in mind, i'm not sure if this is a bug fix or an indication
of some other problem.  a simplified test case --

   ? (let ((os (make-string-output-stream :ELEMENT-TYPE 'BASE-CHAR)))
       (values (typep os 'string-output-stream)
               (funcall (formatter "~A") os 'a 'b)
               (typep os 'string-output-stream)))
   #<SVAR *PACKAGE* 42 #x60266AE>
   (B)
   T

'(formatter "~A") macroexpands to:

   #'(LAMBDA (S &REST ARGS)
       (DECLARE (DYNAMIC-EXTENT ARGS))
       (DO-SUB-FORMAT-0 S "~A" ARGS))

if i remove the (declare (dyanmic-extent args))

   ? (let ((os (make-string-output-stream :ELEMENT-TYPE 'BASE-CHAR)))
       (values (typep os 'string-output-stream)
               (funcall (formatter "~A") os 'a 'b)
               (typep os 'string-output-stream)))
   T
   (B)
   T

my instinct is that it's an interaction between dynamic-extent and the
unused args passed to (funcall (formatter "~A") ..) which are returned
to the caller.

		...bryan