From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: linux-next: tree build failure Date: Wed, 30 Sep 2009 07:29:38 +0100 Message-ID: <4AC316F2020000780001734C@vpn.id2.novell.com> References: <4AC1E15502000078000516B5@vpn.id2.novell.com> <25e057c00909290251h55c0dc25o4ab1f2e84c920dca@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <25e057c00909290251h55c0dc25o4ab1f2e84c920dca-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> Content-Disposition: inline Sender: kvm-ppc-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: roel kluin Cc: sfr-3FnU+UHB4dNDw9hX6IcOSA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, hollisb-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org, kvm-ppc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-next-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-next.vger.kernel.org >>> roel kluin 29.09.09 11:51 >>> >On Tue, Sep 29, 2009 at 11:28 AM, Jan Beulich wrote: >>>>> Hollis Blanchard 09/29/09 2:00 AM >>> >>>First, I think there is a real bug here, and the code should read like >>>this (to match the comment): >>> /* type has to be known at build time for optimization */ >>>- BUILD_BUG_ON(__builtin_constant_p(type)); >>>+ BUILD_BUG_ON(!__builtin_constant_p(type)); >>> >>>However, I get the same build error *both* ways, i.e. >>>__builtin_constant_p(type) evaluates to both 0 and 1? Either that, or >>>the new BUILD_BUG_ON() macro isn't working... >> >> No, at this point of the compilation process it's neither zero nor one, >> it's simply considered non-constant by the compiler at that stage >> (this builtin is used for optimization, not during parsing, and the >> error gets generated when the body of the function gets parsed, >> not when code gets generated from it). >> >> Jan > >then maybe > >if(__builtin_constant_p(type)) > BUILD_BUG_ON(1); > >would work? Definitely not - this would result in the compiler *always* generating an error. Jan -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html