GNU bug report logs - #7928
mktime test in configure: UB resulting in infinite loop

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Package: coreutils;

Reported by: Rich Felker <dalias <at> aerifal.cx>

Date: Thu, 27 Jan 2011 06:44:02 UTC

Severity: normal

Done: Paul Eggert <eggert <at> cs.ucla.edu>

Bug is archived. No further changes may be made.

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From: Bruno Haible <bruno <at> clisp.org>
To: Rich Felker <dalias <at> aerifal.cx>
Cc: bug-gnulib <at> gnu.org, Paul Eggert <eggert <at> cs.ucla.edu>, 7928 <at> debbugs.gnu.org, Eric Blake <eblake <at> redhat.com>
Subject: bug#7928: mktime test in configure: UB resulting in infinite loop
Date: Fri, 28 Jan 2011 18:57:22 +0100

Rich Felker wrote:
> Testing which of the three allowable signed integer
> representations is used is easy: compare ~(t)1 against and -(t)1 and
> -(t)2.

Testing which of the three signed integer representations is in use
is not even needed: Your formula
  ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1)
yields the correct result in all three cases.

Bruno
This bug report was last modified 14 years and 177 days ago.

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