Bug in make-shared-array.

* Bug in make-shared-array.
@ 2006-02-27 23:12 Steve Juranich
  2006-03-03 23:52 ` Kevin Ryde
  0 siblings, 1 reply; 12+ messages in thread
From: Steve Juranich @ 2006-02-27 23:12 UTC (permalink / raw)

I've tried posting a couple of messages about this via gmane.org, but
they still haven't posted to the list, that I can see.  Sorry if
people are seeing multiple versions of this.

There is a bug in scm_make_shared_array that causes things to break
when the input array is 1-d.  I thought I had a working patch for
this, but I don't.  Anyway, the offending line is libguile/unif.c:912:

  SCM_I_ARRAY_BASE (ra) = new_min = new_max = i + SCM_I_ARRAY_BASE (oldra);

As far as I can tell, there is a bug somewhere in the SCM_I_ARRAY_BASE
macro that causes things to break when oldra is a 1d uniform array. 
The value of the array base seems to be sane for multi-dimensional
arrays, but is something very strange for 1d arrays.

Here's the proof:

<buggy.c>
#include <stdio.h>
#include <libguile.h>

SCM
show_base_wrap(SCM ra) {
  size_t base = SCM_I_ARRAY_BASE(ra);
  printf("base = %d.\n", base);
  return SCM_UNSPECIFIED;
}

void
init_buggy () {
  scm_c_define_gsubr("show-base", 1, 0, 0, show_base_wrap);
}
</buggy.c>

Then the scheme code that shows this off would be:
<proof.scm>
#! /bin/bash
exec guile -s "$0" "$@"
!#

(use-modules (ice-9 format))

(setenv "LD_LIBRARY_PATH" (string-append ".:" (getenv "LD_LIBRARY_PATH")))

(load-extension "buggy" "init_buggy")

(define good #2((a b c) (d e f) (g h i)))
(define bad  #1(a b c d e f g h i))

(format #t "This one should work:~%~!")
(show-base good)

(format #t "While this one should be weird.~%~!")
(show-base bad)
</proof.scm>

Are there any workarounds for this?

BTW:
GCC 3.4.4
libtool-1.5.2
SuSE 9.3 everything else.

Thanks a bunch.
--
Steve Juranich
Tucson, AZ
USA

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