GNU bug report logs - #14879
fixnum-width, greatest-fixnum and least-fixnum disagree

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

From: Göran Weinholt <goran <at> weinholt.se>
To: bug-guile <at> gnu.org
Subject: fixnum-width, greatest-fixnum and least-fixnum disagree
Date: Tue, 16 Jul 2013 16:02:55 +0200

[Message part 1 (text/plain, inline)]

Hello schemers,

scheme@(guile-user)> (import (rnrs))
scheme@(guile-user)> (fixnum-width)
$1 = 61
scheme@(guile-user)> (greatest-fixnum)
$2 = 2305843009213693951
scheme@(guile-user)> (least-fixnum)
$3 = -2305843009213693952

If the reported fixnum width is correct, then these should be the least
and greatest fixnums:

  (- (expt 2 (- (fixnum-width) 1)))   => -1152921504606846976
  (- (expt 2 (- (fixnum-width) 1)) 1) => 1152921504606846975

If the reported least and greatest fixnums are correct, then the fixnum
width is actually 62.

Tested with 2.0.9.33-3bbca-dirty on an amd64 system.

Regards,

-- 
Göran Weinholt <goran <at> weinholt.se>
20             JUSTICE KENNEDY:  That seems odd.  I mean,
21 Microsoft doesn't say please buy our disk because it's
22 the prettiest disk in the business.

[Message part 2 (application/pgp-signature, inline)]

Message #10 received at 14879-done <at> debbugs.gnu.org (full text, mbox):

From: Mark H Weaver <mhw <at> netris.org>
To: Göran Weinholt <goran <at> weinholt.se>
Cc: 14879-done <at> debbugs.gnu.org
Subject: Re: bug#14879: fixnum-width, greatest-fixnum and least-fixnum disagree
Date: Tue, 16 Jul 2013 17:41:41 -0400

Göran Weinholt <goran <at> weinholt.se> writes:

> scheme@(guile-user)> (import (rnrs))
> scheme@(guile-user)> (fixnum-width)
> $1 = 61
> scheme@(guile-user)> (greatest-fixnum)
> $2 = 2305843009213693951
> scheme@(guile-user)> (least-fixnum)
> $3 = -2305843009213693952
>
> If the reported fixnum width is correct, then these should be the least
> and greatest fixnums:
>
>   (- (expt 2 (- (fixnum-width) 1)))   => -1152921504606846976
>   (- (expt 2 (- (fixnum-width) 1)) 1) => 1152921504606846975
>
> If the reported least and greatest fixnums are correct, then the fixnum
> width is actually 62.

That's correct.  Fixed in 06903786211afd9a554b8f009a37111f729607ee.

    Thanks!
      Mark

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