Date: Sat, 29 Jun 2013 09:42:49 -0700 From: mdf@FreeBSD.org To: Tim Kientzle <kientzle@freebsd.org> Cc: Konstantin Belousov <kostikbel@gmail.com>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org> Subject: Re: svn commit: r252376 - head/lib/libutil Message-ID: <CAMBSHm_%2BYwAp2egVZefBar_V6acC4erMm3LyTj62KFxHPunCgQ@mail.gmail.com> In-Reply-To: <A89C1472-264E-4B9C-8711-763ED156E9D2@FreeBSD.org> References: <201306291552.r5TFqnLV022460@svn.freebsd.org> <20130629161914.GD91021@kib.kiev.ua> <A89C1472-264E-4B9C-8711-763ED156E9D2@FreeBSD.org>
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On Sat, Jun 29, 2013 at 9:36 AM, Tim Kientzle <kientzle@freebsd.org> wrote: > > On Jun 29, 2013, at 9:19 AM, Konstantin Belousov wrote: > > > On Sat, Jun 29, 2013 at 03:52:49PM +0000, Tim Kientzle wrote: > >> Author: kientzle > >> Date: Sat Jun 29 15:52:48 2013 > >> New Revision: 252376 > >> URL: http://svnweb.freebsd.org/changeset/base/252376 > >> > >> Log: > >> Fix -Wunsequenced warning > > What is this ? From the name of the warning, it sounds as if the problem > > is in the lack of sequence point between two modifications of the same > > variable in the expression ? > > > > But, there function' argument evaluation and function call are separated > > by seq point, AFAIR. Could you, please, clarify ? > > I think you're right about that, though I'd have to > look at the spec to be sure. > > Not sure why clang would report this as a -Wunsequenced > warning. The implied store here is certainly redundant, though. > It may be like other warnings (-Wmissing-field-initializers, I'm looking at you) that warn about currently correct, but potentially problematic behavior. In particular, if any of the functions is re-implemented as a macro, the sequence point goes away, and this code is broken without the code's author having made any changes. So it seems like a reasonable warning. Thanks, matthew
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