Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!columbia!vail.cs.columbia.edu!djk
From: djk@vail.cs.columbia.edu (David Kurlander)
Newsgroups: comp.lang.lisp
Subject: Bugs in Lucid?
Message-ID: <6150@columbia.edu>
Date: 31 Jan 89 19:33:40 GMT
Sender: news@columbia.edu
Reply-To: djk@vail.cs.columbia.edu (David Kurlander)
Organization: Columbia University Department of Computer Science
Lines: 43

This past week I started to use some of Common Lisp's advanced array
features, sometimes achieving quite unexpected results.  I think that
I've stumbled upon two bugs in Lucid Common Lisp, but there's a small
chance that I might be using displaced offsets incorrectly.  I would
appreciate it if a CommonLisp guru could tell me whether the former or
latter is true.

Bug1:

(setq *print-circle* t)
(setq *print-array* t)

(setq a (make-array 100))
(setq b (make-array 3 :displaced-to a :displaced-index-offset 10))
(setq c (make-array 3 :displaced-to a :displaced-index-offset 25))

(setq text (list b c))

Now, when I type "text" to the interpreter, I get the following
result: (#1=#(NIL NIL NIL) #1).  Yet the (car text) is not eq to (cadr
text)!


Bug2:

(setq u (make-array 400 :element-type 'string-char :fill-pointer t))
(replace u "Common Lisp")
(setf (fill-pointer u) 11)
(setq y (make-array 10 :element-type 'string-char :fill-pointer t
		    :displaced-to u :displaced-index-offset 6))
(setf (fill-pointer y) 5)
(vector-push #\* y)

I would expect the asterisk to be placed at position 5 of y, but
instead it appears at 5 of u!

By the way, I'm running HPCL II A.02.01, a repackaged version of Lucid
2.1 by Hewlett-Packard.  The first bug also appears on a Sun 4
running Sun Development Environment 2.1, another repackaged version of
Lucid.  I didn't get a chance to test out bug #2 on the Sun.

David Kurlander
djk@columbia.edu