From: Jeffrey Walton <noloader@gmail.com>
Subject: Re: UB in general ... and linux/bitops.h in particular
Date: Thu, 5 May 2016 22:25:16 -0400
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Cc: "H. Peter Anvin" <hpa@zytor.com>, "Theodore Ts'o" <tytso@mit.edu>,
	linux-kernel@vger.kernel.org,
	Stephan Mueller <smueller@chronox.de>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Andi Kleen <andi@firstfloor.org>,
	Sandy Harris <sandyinchina@gmail.com>,
	cryptography@lakedaemon.net, linux-crypto@vger.kernel.org
To: John Denker <jsd@av8n.com>
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Sender: linux-crypto-owner@vger.kernel.org

>    -- Perhaps the compiler guys could be persuaded to support
>     the needed features explicitly, perhaps via a command-line
>     option: -std=vanilla
>     This should be a no-cost option as things stand today, but
>     it helps to prevent nasty surprises in the future.

It looks LLVM has the -rainbow option; see
http://blog.llvm.org/2016/04/undefined-behavior-is-magic.html :)

Jeff