loop destructuring with type error

[`bg`]

A loop example from CLHS: http://www.lispworks.com/documentation/lw51/CLHS/Body/06_aag.htm

;; If all the types are the same, this way is even simpler.
(loop for (a b c) of-type float in
       '((1.0 2.0 4.0) (5.0 6.0 8.3) (8.0 9.0 10.4))
       collect (list c b a))

Expected to return: ((4.0 2.0 1.0) (8.3 6.0 5.0) (10.4 9.0 8.0))
But instead SBCL signals a SIMPLE-TYPE-ERROR:

Value of NIL in
  (LET ((A 0.0)
        (B 0.0)
        (C 0.0)
        (#1=#:LOOP-IGNORE-1107 NIL)
        (#2=#:LOOP-LIST-1106
         '((1.0 2.0 4.0) (5.0 6.0 8.3) (8.0 9.0 10.4))))
    (DECLARE (TYPE LIST #2#)
             (TYPE FLOAT #1#)
             (IGNORE #1#)
             (TYPE FLOAT C)
             (TYPE FLOAT B)
             (TYPE FLOAT A))
    (SB-LOOP::WITH-LOOP-LIST-COLLECTION-HEAD #3=(#4=#:LOOP-LIST-HEAD-1108
                                                 #:LOOP-LIST-TAIL-1109)
      (SB-LOOP::LOOP-BODY NIL
                          (NIL
                           (SB-LOOP::LOOP-REALLY-DESETQ
                            #5=(A B C) #6=(CAR #2#))
                           NIL
                           (SB-LOOP::LOOP-REALLY-DESETQ #2#
                                                        #7=(CDR
                                                            #2#)))
                          ((SB-LOOP::LOOP-COLLECT-RPLACD #3#
                                                         (LIST
                                                          (LIST
                                                           C B
                                                           A))))
                          ((WHEN (ENDP #2#)
                             (GO SB-LOOP::END-LOOP))
                           (SB-LOOP::LOOP-REALLY-DESETQ #5# #6#)
                           NIL
                           (SB-LOOP::LOOP-REALLY-DESETQ #2#
                                                        #7#))
                          ((RETURN-FROM NIL
                             (SB-LOOP::LOOP-COLLECT-ANSWER
                              #4#))))))

is
  NIL,
not a
  FLOAT.
   [Condition of type SIMPLE-TYPE-ERROR]

sbcl --version
SBCL 1.1.18

Linux hostname 3.12.13-gentoo #1 SMP PREEMPT Sun Mar 9 17:59:44 MDT 2014 x86_64 Intel(R) Core(TM)2 CPU T7600 @ 2.33GHz GenuineIntel GNU/Linux

[Stas Boukarev (stassats)]

In a5ac94abb11975f334d3eb18f6f339b9e7dc5a5d.