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From: Mark Wielaard <mjw@redhat.com>
To: elfutils-devel@lists.fedorahosted.org
Subject: Re: [PATCH] elfcmp: fix self-comparison error with GCC 6
Date: Mon, 11 Apr 2016 17:13:58 +0200
Message-ID: <1460387638.7712.27.camel@redhat.com>
In-Reply-To: 1460383257-13019-1-git-send-email-david.abdurachmanov@cern.ch

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On Mon, 2016-04-11 at 16:00 +0200, david.abdurachmanov(a)cern.ch wrote:
> From: David Abdurachmanov <davidlt@cern.ch>
> =

> Noticed with Fedora 24 Alpha, gcc (GCC) 6.0.0 20160406
> (Red Hat 6.0.0-0.20).
> =

> elfcmp.c: In function =E2=80=98main=E2=80=99:
> elfcmp.c:364:199: error: self-comparison always evaluates
> to false [-Werror=3Dtautological-compare]
>         if (unlikely (name1 =3D=3D NULL || name2 =3D=3D NULL
> @@ -368,7 +368,7 @@ main (int argc, char *argv[])
>  				&& sym1->st_shndx !=3D SHN_UNDEF)
>  			    || sym1->st_info !=3D sym2->st_info
>  			    || sym1->st_other !=3D sym2->st_other
> -			    || sym1->st_shndx !=3D sym1->st_shndx))
> +			    || sym1->st_shndx !=3D sym2->st_shndx))
>  		{
>  		  // XXX Do we want to allow reordered symbol tables?
>  		symtab_mismatch:

Thanks! And oops. Applied since that was obviously wrong.

Nice that GCC caught that. I am slightly surprised my own GCC6 testing
didn't find this. I am using upstream gcc (GCC) 6.0.0 20160410
(experimental). Did you have to do anything special on your Fedora setup
to make GCC detect this?

Thanks,

Mark
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