From: Paul Eggert <eggert@cs.ucla.edu>
To: Dmitry Antipov <dmantipov@yandex.ru>
Cc: 18361@debbugs.gnu.org
Subject: bug#18361: New 'sort' implementation can crash Emacs
Date: Sat, 30 Aug 2014 06:44:54 -0700 [thread overview]
Message-ID: <5401D556.4060102@cs.ucla.edu> (raw)
In-Reply-To: <54017555.8010903@yandex.ru>
Dmitry Antipov wrote:
> couldn't we detect an improper comparison
> function at runtime?
Not easily, because it doesn't suffice to check whether the function is
antisymmetrical at each comparison (a local property). One must check
whether the function defines a total order (a global property). One way
to do such a check is to sort the array, and then compare all pairs to
verify that the function is indeed a total order. But of course that
begs the question of sorting the array, plus it's an O(N**2) check, so
it's not practical.
next prev parent reply other threads:[~2014-08-30 13:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-29 21:24 bug#18361: New 'sort' implementation can crash Emacs Paul Eggert
2014-08-29 22:47 ` Dmitry Antipov
2014-08-29 23:07 ` Paul Eggert
2014-08-30 5:07 ` Dmitry Antipov
2014-08-30 5:22 ` Paul Eggert
2014-08-30 6:55 ` Dmitry Antipov
2014-08-30 13:44 ` Paul Eggert [this message]
2014-08-30 23:05 ` Paul Eggert
2014-08-31 2:50 ` Eli Zaretskii
2014-08-31 4:46 ` Paul Eggert
2014-08-31 15:20 ` Eli Zaretskii
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