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NNTP-Posting-Date: Sat, 29 Apr 2017 01:00:36 -0500
From: Gareth Owen <gwowen@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: gcc failure (optimised/non-optimised)
References: <odf2pf$dd0$1@dont-email.me> <odf5er$m60$1@flame.srcf.net> <odf8vf$1v1$1@dont-email.me> <87shl0enji.fsf@gmail.com> <odkbhl$72p$1@dont-email.me> <ln7f29q0pw.fsf@kst-u.example.com> <oe0c6j$b2v$1@dont-email.me> <77bf027a-bf2c-41c1-8daa-bade4b803842@googlegroups.com>
Date: Sat, 29 Apr 2017 07:00:35 +0100
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Xref: csiph.com comp.lang.c:108712

supercat@casperkitty.com writes:

>       if (message+5 == &magic)

I think this equality expression may be UB in C11 (S6.5.8.5)
It's merely unspecified in C++.