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Re: gnulib vasnprintf change introduced a bug

From: Thien-Thi Nguyen
Subject: Re: gnulib vasnprintf change introduced a bug
Date: Mon, 01 Sep 2014 07:55:01 +0200
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4.50 (gnu/linux)

() Paul Eggert <address@hidden>
() Sun, 31 Aug 2014 19:23:53 -0700

   The recent change [...] introduced a bug because 'tmp + width'
   has undefined behavior if the resulting pointer would fall
   outside the containing buffer (this is true even though the
   pointer is not dereferenced).

I believe the C11 spec describes this behavior in §6.5.6 ¶8,
"Additive Operators" (in my draft copy, at least).  Is that
correct?  Anywhere else i should look to learn more?

   [...] better to use -Wno-sign-compare, as the signal-to-noise
   ratio with -Wsign-compare is too high, and it's too tempting to
   introduce bugs such as this one.

Yes, i surely fell for it.

   That being said, I worked around this problem with the attached
   further patch, which fixes somewhat-related issues that I also


Thien-Thi Nguyen
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