Steel Bank Common Lisp

What declarations are needed to compile this without type uncertainty?

(DEFUN COPY (SRC FROM-SRC DST FROM-DST LENGTH)
  (DECLARE (STRING SRC DST) (FIXNUM FROM-SRC FROM-DST LENGTH))
  (WHILE (< 0 LENGTH)
    (SETF (CHAR DST FROM-DST) (CHAR SRC FROM-SRC))
    (INCF FROM-DST)
    (INCF FROM-SRC)
    (DECF LENGTH))
  ) ;;COPY


;     (SETF (CHAR COM.INFORMATIMAGO.COMMON-LISP.PACKAGE::DST
;               COM.INFORMATIMAGO.COMMON-LISP.PACKAGE::FROM-DST)
;           (CHAR COM.INFORMATIMAGO.COMMON-LISP.PACKAGE::SRC
;                 COM.INFORMATIMAGO.COMMON-LISP.PACKAGE::FROM-SRC))
; --> SB-KERNEL:%CHARSET SB-KERNEL:%ASET LET* SB-KERNEL:HAIRY-DATA-VECTOR=
-SET=20
; --> MULTIPLE-VALUE-BIND MULTIPLE-VALUE-CALL=20
; =3D=3D>
;   (SB-KERNEL:%DATA-VECTOR-AND-INDEX ARRAY SB-INT:INDEX)
;=20
; note: unable to
;         optimize
;       due to type uncertainty:
;         The first argument is a BASE-STRING, not a SIMPLE-ARRAY.

(Typical usage of COPY would be:
      (let ((dst (make-string 10)))
         (copy "hello" 0 dst 0 5)
         (copy "world" 0 dst 5 5)
         dst)
)

--=20
__Pascal_Bourguignon__                   http://www.informatimago.com/
----------------------------------------------------------------------
Do not adjust your mind, there is a fault in reality.

What does this error mean?


; compiling top level form:=20
unhandled condition (of type SIMPLE-ERROR):
  Non-:DEFAULT EXTERNAL-FORMAT values are not supported.

; compiling file "/local/users/pascal/src/common/lisp/common-lisp/string.=
lisp" (written 06 MAY 2003 08:09:27 AM):
0: ("hairy arg processor for top level local call SB!DEBUG:BACKTRACE"
    128
    #<SYNONYM-STREAM :SYMBOL SB-SYS:*STDERR* {505B9B9}>)
1: (SB-IMPL::NOPROGRAMMER-DEBUGGER-HOOK-FUN
    2
    #<SIMPLE-ERROR {919FA99}>
    #<unavailable argument>)[:EXTERNAL]
2: (INVOKE-DEBUGGER 1 #<SIMPLE-ERROR {919FA99}>)[:EXTERNAL]
3: (ERROR 1 "Non-:DEFAULT EXTERNAL-FORMAT values are not supported.")[:EX=
TERNAL]
4: (LOAD 9 "/home/pascal/src/common/lisp/common-lisp/list")[:EXTERNAL]



I'm  compiling   a  file,  and   since  require/provide/*modules*  are
deprecated,  I'm  using  load  (indirectly, thru  a  macro  (eval-when
(:compile-toplevel  :load-toplevel)   (load  "...")))   to   load  the
dependencies.  It compiled correctly in clisp and cmucl.

-rw-------    1 pascal   regular     13990 May  6 08:18 list.fas
-rw-------    1 pascal   regular     31172 May  6 08:32 list.fasl
-rw-------    1 pascal   regular      4874 May  6 08:18 list.lib
-rw-r--r--    1 pascal   regular     13404 May  6 08:16 list.lisp
-rw-------    1 pascal   regular     22668 May  6 08:19 list.x86f



--=20
__Pascal_Bourguignon__                   http://www.informatimago.com/
----------------------------------------------------------------------
Do not adjust your mind, there is a fault in reality.