[Sbcl-devel] Bug report and fix for (describe (make-array '()))

[Lutz E. <eu...@we...>]

Hi,

I am using sbcl-0.7.10 and noticed a bug in describe,
namely it can't describe arrays of rank 0:

* (describe (make-array '()))

debugger invoked on condition of type TYPE-ERROR:
  The value #0A0 is not of type VECTOR.
[...]

The same error occurs in cmucl-18b.

Here is a fix:

In the file "src/code/describe.lisp" change the method
on describe-object for arrays as follows:

(defmethod describe-object ((x array) s)
  (let ((rank (array-rank x)))
    (cond ((= rank 1)
           (format s
                   "~@:_~S is a ~:[~;displaced ~]vector of length ~S." x
                   (and (array-header-p x) (%array-displaced-p x)) (length x))
           (when (array-has-fill-pointer-p x)
             (format s "~@:_It has a fill pointer, currently ~S."
                     (fill-pointer x))))
          (t
           (format s "~S ~_is " x)
           (write-string (if (%array-displaced-p x) "a displaced" "an") s)
           (format s " array of rank ~S." rank)
           (unless (= rank 0)
             (format s "~@:_Its dimensions are ~S." (array-dimensions x))))))
  (let ((array-element-type (array-element-type x)))
    (unless (eq array-element-type t)
      (format s
              "~@:_Its element type is specialized to ~S."
              array-element-type))))

Yours

Lutz Euler
______________________________________________________________________________
Sieben auf einen Streich? Mit der Gruppen-SMS von WEB.DE FreeMail 
kein Problem. http://freemail.web.de/features/?mc=021179