GNU bug report logs - #17556
24.4.50; fix math-bignum

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Package: emacs;

Reported by: Leo Liu <sdl.web <at> gmail.com>

Date: Fri, 23 May 2014 04:48:01 UTC

Severity: normal

Found in version 24.4.50

Done: Leo Liu <sdl.web <at> gmail.com>

Bug is archived. No further changes may be made.

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Report forwarded to jay.p.belanger <at> gmail.com, bug-gnu-emacs <at> gnu.org:
bug#17556; Package emacs. (Fri, 23 May 2014 04:48:02 GMT) Full text and rfc822 format available.
Acknowledgement sent to Leo Liu <sdl.web <at> gmail.com>:
New bug report received and forwarded. Copy sent to jay.p.belanger <at> gmail.com, bug-gnu-emacs <at> gnu.org. (Fri, 23 May 2014 04:48:02 GMT) Full text and rfc822 format available.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Leo Liu <sdl.web <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.4.50; fix math-bignum
Date: Fri, 23 May 2014 12:46:05 +0800

Due to integer overflow (math-bignum most-negative-fixnum) is incorrect.
Any objection if I fix it like in this patch:

=== modified file 'lisp/calc/calc.el'
--- lisp/calc/calc.el	2014-01-01 07:43:34 +0000
+++ lisp/calc/calc.el	2014-05-23 04:42:18 +0000
@@ -2773,9 +2773,15 @@
 
 ;; Coerce integer A to be a bignum.  [B S]
 (defun math-bignum (a)
-  (if (>= a 0)
-      (cons 'bigpos (math-bignum-big a))
-    (cons 'bigneg (math-bignum-big (- a)))))
+  (cond
+   ((>= a 0)
+    (cons 'bigpos (math-bignum-big a)))
+   ((= a most-negative-fixnum)
+    ;; Note: (- most-negative-fixnum) is most-negative-fixnum
+    (math-sub (cons 'bigneg (math-bignum-big (- (1+ a))))
+	      1))
+   (t
+    (cons 'bigneg (math-bignum-big (- a))))))
 
 (defun math-bignum-big (a)   ; [L s]
   (if (= a 0)
Information forwarded to bug-gnu-emacs <at> gnu.org:
bug#17556; Package emacs. (Fri, 23 May 2014 07:34:02 GMT) Full text and rfc822 format available.

Message #8 received at 17556 <at> debbugs.gnu.org (full text, mbox):

From: Andreas Schwab <schwab <at> linux-m68k.org>
To: Leo Liu <sdl.web <at> gmail.com>
Cc: 17556 <at> debbugs.gnu.org
Subject: Re: bug#17556: 24.4.50; fix math-bignum
Date: Fri, 23 May 2014 09:33:36 +0200

Leo Liu <sdl.web <at> gmail.com> writes:

> +    (math-sub (cons 'bigneg (math-bignum-big (- (1+ a))))

aka                                             (- 1 a)

Andreas.

-- 
Andreas Schwab, schwab <at> linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."
Information forwarded to bug-gnu-emacs <at> gnu.org:
bug#17556; Package emacs. (Fri, 23 May 2014 08:24:02 GMT) Full text and rfc822 format available.

Message #11 received at 17556 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Andreas Schwab <schwab <at> linux-m68k.org>, Leo Liu <sdl.web <at> gmail.com>
Cc: 17556 <at> debbugs.gnu.org
Subject: Re: bug#17556: 24.4.50; fix math-bignum
Date: Fri, 23 May 2014 10:23:26 +0200

>> +    (math-sub (cons 'bigneg (math-bignum-big (- (1+ a))))
>
> aka                                             (- 1 a)

Hmmm...

martin
Information forwarded to bug-gnu-emacs <at> gnu.org:
bug#17556; Package emacs. (Fri, 23 May 2014 09:46:02 GMT) Full text and rfc822 format available.

Message #14 received at 17556 <at> debbugs.gnu.org (full text, mbox):

From: Leo Liu <sdl.web <at> gmail.com>
To: Andreas Schwab <schwab <at> linux-m68k.org>
Cc: 17556 <at> debbugs.gnu.org
Subject: Re: bug#17556: 24.4.50; fix math-bignum
Date: Fri, 23 May 2014 17:44:24 +0800

On 2014-05-23 09:33 +0200, Andreas Schwab wrote:
> aka                                             (- 1 a)

aka most-positive-fixnum ;)

Leo
Reply sent to Leo Liu <sdl.web <at> gmail.com>:
You have taken responsibility. (Sat, 24 May 2014 15:22:02 GMT) Full text and rfc822 format available.
Notification sent to Leo Liu <sdl.web <at> gmail.com>:
bug acknowledged by developer. (Sat, 24 May 2014 15:22:03 GMT) Full text and rfc822 format available.

Message #19 received at 17556-done <at> debbugs.gnu.org (full text, mbox):

From: Leo Liu <sdl.web <at> gmail.com>
To: 17556-done <at> debbugs.gnu.org
Subject: Re: bug#17556: 24.4.50; fix math-bignum
Date: Sat, 24 May 2014 23:19:50 +0800

Fixed in 24.5
bug archived. Request was from Debbugs Internal Request <help-debbugs <at> gnu.org> to internal_control <at> debbugs.gnu.org. (Sun, 22 Jun 2014 11:24:04 GMT) Full text and rfc822 format available.
This bug report was last modified 10 years and 161 days ago.

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