Date: Sun, 7 Jun 2009 09:09:04 +0200
From: Sam Ravnborg <sam@ravnborg.org>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: Jaswinder Singh Rajput <jaswinder@kernel.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ingo Molnar <mingo@elte.hu>, Catalin Marinas <catalin.marinas@arm.com>,
       Tony Luck <tony.luck@intel.com>,
       Geert Uytterhoeven <geert@linux-m68k.org>,
       Greg Ungerer <gerg@snapgear.com>, Ralf Baechle <ralf@linux-mips.org>,
       Michael Abbott <michael@araneidae.co.uk>,
       Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>,
       David Howells <dhowells@redhat.com>
Subject: Re: [GIT PULL] headers_check fixes
Message-ID: <20090607070904.GA11128@uranus.ravnborg.org>
References: <1244118232.5172.26.camel@ht.satnam> <1244292857.2473.4.camel@ht.satnam> <20090606130210.GA9343@flint.arm.linux.org.uk> <1244299177.2473.21.camel@ht.satnam> <20090606214711.GA4813@flint.arm.linux.org.uk> <20090606221223.GA20945@uranus.ravnborg.org> <20090606232415.GB4813@flint.arm.linux.org.uk>
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On Sun, Jun 07, 2009 at 12:24:15AM +0100, Russell King wrote:
> On Sun, Jun 07, 2009 at 12:12:23AM +0200, Sam Ravnborg wrote:
> > Hi Russell.
> > 
> > On Sat, Jun 06, 2009 at 10:47:11PM +0100, Russell King wrote:
> > > Right, below is a patch to unifdef.c which allows it to work out if
> > > an #if expression always evaluates true or false for symbols which
> > > are being undefined/always defined.
> > > 
> > > The patch is slightly more complicated than I'd hoped because unifdef
> > > needs to see lines fully evaluated - doing otherwise causes it to
> > > mark the line as "dirty" and copy it over no matter what.
> > > 
> > > What follows this email is the diff of what effect it has on the
> > > headers copied over - as can be seen, all resulting changes are of
> > > net benefit.
> > 
> > You beat me on this one.
> > I was looking into supportting short_circuit_and/short_circuit_or too.
> > Your patch looks better - thanks!
> > 
> > >From my very limited testing this patch suffers from a problem I faced too.
> > When you run it on for example hwcap.h or my sample file:
> > #if defined(__KERNEL__) && !defined(__ASSEMBLY__)
> >   int a;
> > #endif
> > 
> > then the return code of the program is 1 so we do not copy the file.
> 
> That's correct.  If unifdef removes any lines, the exit code is 1, not
> zero.  This happens with the unmodified unifdef as well, so I'm not
> changing that behaviour.

Thanks.
I was just fooled in my testing.
With the same file I saw two different return codes with and
without the patch. But this is because you fixed unifdef.

	Sam
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