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Date:   Fri, 7 Sep 2018 20:13:38 +0200
From:   Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     christophe.leroy@c-s.fr, joe@perches.com,
        Kees Cook <keescook@chromium.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-sparse@vger.kernel.org, sparse@chrisli.org
Subject: Re: Conflict between sparse and commit cafa0010cd51f ("Raise the
 minimum required gcc version to 4.6")
Message-ID: <20180907181337.peyfq7yvhahduvmq@ltop.local>
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On Fri, Sep 07, 2018 at 10:22:56AM -0700, Nick Desaulniers wrote:
> On Fri, Sep 7, 2018 at 7:34 AM Christophe LEROY <christophe.leroy@c-s.fr> wrote:
> >
> > Cc linux-sparse@vger.kernel.org
> >
> > Le 07/09/2018 ? 14:22, Christophe Leroy a ?crit :
> > > Since commit cafa0010cd51f ("Raise the minimum required gcc version to
> > > 4.6"), sparse check fails as follows:
> > >
> > > [root@pc16082vm linux-powerpc]# make C=2 arch/powerpc/kernel/process.o
> > >    CALL    scripts/checksyscalls.sh
> > >    CHECK   scripts/mod/empty.c
> > > ./include/linux/compiler-gcc.h:14:3: error: Sorry, your compiler is too
> > > old - please upgrade it.
> > >    CHECK   arch/powerpc/kernel/process.c
> > > ./include/linux/compiler-gcc.h:14:3: error: Sorry, your compiler is too
> > > old - please upgrade it.
> > >
> > >
> > > I have sparse version 0.5.2
> > >
> > > What can be done to fix that ?
> > >
> > > Christophe
> 
> Oof, sorry Christophe.  Looks like that's the latest version of sparse:
> https://sparse.wiki.kernel.org/index.php/Main_Page#News
> 
> I'm curious what sparse expands __GNUC__, __GNUC_MINOR__, and
> __GNUC_PATCHLEVEL__ to?  Pre commit cafa0010cd51f, it MUST be
> expanding them to something, otherwise you'd have seen the error then,
> too.  The previous check was GCC < 3.3, now it's GCC < 4.6.

Sparse expand these macros to the same version than the compiler used
to compile GCC. I find a bit strange though to have sparse v0.5.2 but
using an old compiler.
 
Also, it's worth to look at what is said in this email:
  https://lore.kernel.org/lkml/CA+55aFzYEnZR2GZLR-DwpONjMNYGYoDy+6AWLCVNayWiaZuqoA@mail.gmail.com/


-- Luc