From: Eli Zaretskii <eliz@gnu.org>
To: bug-gnulib@gnu.org
Subject: INT_ADD_WRAPV and friends considered harmful
Date: Mon, 12 Aug 2019 17:47:17 +0300 [thread overview]
Message-ID: <837e7itp8q.fsf@gnu.org> (raw)
Please take a look at the problem described in this bug report:
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=37006
The upshot is that an innocent use of INT_ADD_WRAPV, even by
experienced programmers, can quite unexpectedly produce spectacular
failures. Frankly, I was astonished to discover this failure mode,
especially as it isn't clearly documented in the comments in
intprops.h.
AFAIU, INT_ADD_WRAPV and its ilk are safety devices: they prevent code
from failing in subtle and rare situations. And safety devices cannot
themselves be unsafe, because that would contradict the raison d'être
of their very existence.
So I urge the Gnulib developers to please fix this deficiency, and
make these macros safe in such simple use cases.
TIA
next reply other threads:[~2019-08-12 14:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-12 14:47 Eli Zaretskii [this message]
2019-08-15 0:48 ` INT_ADD_WRAPV and friends - bug fixed Paul Eggert
2019-08-15 14:09 ` Eli Zaretskii
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