Re: [PATCH 0/4] drop some "int x = x" hacks to silence gcc warnings

From: Johannes Sixt <j.sixt@viscovery.net>
Date: Mar 21, 2013, 11:45 UTC
Message-ID: <514AF2E1.7020409@viscovery.net>
In-Reply-To: <20130321110338.GA18552@sigill.intra.peff.net>

Am 3/21/2013 12:03, schrieb Jeff King:

> I was fooling around with clang and noticed that it complains about the
> "int x = x" construct under -Wall. That is IMHO a deficiency in clang,
> since the idiom has a well-defined use in silencing -Wuninitialized
> warnings.

IMO, that's a myth. The construct invokes undefined behavior at least since C99, and the compilers are right to complain about it.

But you might just say that standards are not worth the paper they are printed on, and you may possibly be right for practical reasons. But I still consider it a myth that "int x = x" is an idiom. I'm in the C business since more than 25 years, and the first time I saw the "idiom" was in git code. Is there any evidence that the construct is used elsewhere? Have I been in the wrong corner of the C world for such a long time?

-- Hannes