Subject: Re: linux-next: tree build failure
From: Hollis Blanchard <hollisb@us.ibm.com>
To: Jan Beulich <jbeulich@novell.com>
Cc: sfr@canb.auug.org.au, akpm@linux-foundation.org,
       linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org,
       linux-kernel@vger.kernel.org, linux-next@vger.kernel.org
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Content-Type: text/plain
Organization: IBM Linux Technology Center
Date: Tue, 29 Sep 2009 16:39:32 -0700
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On Tue, 2009-09-29 at 10:28 +0100, 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).

I think I see what you're saying. Do you have a fix to suggest?

-- 
Hollis Blanchard
IBM Linux Technology Center

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