From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:58422)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <benoit.canet@irqsave.net>) id 1WimCX-0006ep-UB
	for qemu-devel@nongnu.org; Fri, 09 May 2014 10:55:10 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <benoit.canet@irqsave.net>) id 1WimCS-0000XG-Sm
	for qemu-devel@nongnu.org; Fri, 09 May 2014 10:55:05 -0400
Received: from lputeaux-656-01-25-125.w80-12.abo.wanadoo.fr
	([80.12.84.125]:60352 helo=paradis.irqsave.net)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <benoit.canet@irqsave.net>) id 1WimCS-0000X4-MD
	for qemu-devel@nongnu.org; Fri, 09 May 2014 10:55:00 -0400
Date: Fri, 9 May 2014 16:55:31 +0200
From: =?iso-8859-1?Q?Beno=EEt?= Canet <benoit.canet@irqsave.net>
Message-ID: <20140509145530.GA19008@irqsave.net>
References: <1399562319-26873-1-git-send-email-benoit.canet@irqsave.net>
	<87wqdwgm2e.fsf@blackfin.pond.sub.org>
	<20140508200455.GA28563@irqsave.net>
	<87a9arbjj4.fsf@blackfin.pond.sub.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
In-Reply-To: <87a9arbjj4.fsf@blackfin.pond.sub.org>
Content-Transfer-Encoding: quoted-printable
Subject: Re: [Qemu-devel] [PATCH] qapi: Make the include directive
	idempotent.
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Markus Armbruster <armbru@redhat.com>
Cc: =?iso-8859-1?Q?Beno=EEt?= Canet <benoit.canet@irqsave.net>, vilanova@ac.upc.edu, qemu-devel@nongnu.org, lcapitulino@redhat.com

The Friday 09 May 2014 =E0 07:36:31 (+0200), Markus Armbruster wrote :
> Beno=EEt Canet <benoit.canet@irqsave.net> writes:
>=20
> > The Thursday 08 May 2014 =E0 20:30:33 (+0200), Markus Armbruster wrot=
e :
> [...]
> >> There are two reasons to detect cycles.  The technical one is preven=
ting
> >> infinite expansion.  No longer applies with idempotent include.  The
> >> other, more abstract one is rejecting nonsensical use of the include
> >> directive.  I think that one still applies.
> [...]
> >> > @@ -102,17 +102,16 @@ class QAPISchema:
> >> >                                          'Expected a file name (st=
ring), got: %s'
> >> >                                          % include)
> >> >                  include_path =3D os.path.join(self.input_dir, inc=
lude)
> >> > -                if any(include_path =3D=3D elem[1]
> >> > -                       for elem in self.include_hist):
> >> > -                    raise QAPIExprError(expr_info, "Inclusion loo=
p for %s"
> >> > -                                        % include)
> >> > +                # make include idempotent by skipping further inc=
ludes
> >> > +                if include_path in [x[1] for x in  include_hist]:
> >> > +                    continue
> >>=20
> >> Loses cycle detection.
> >
> > It simply also skip cycle includes. If cycle are skipped then cannot =
do no
> > harm.
>=20
> Your argument is based exclusively on the technical reason to detect
> cycles: cycles need to be caught because they cause infinite recursion.
> Since there is no infinite recursion with idempotent include, cycles ar=
e
> just fine.
>=20
> I'm arguing from a more abstract point of view: cycles should be
> rejected because they're nonsensical.  The fact that they can cause
> infinite recursion is an implementation detail.  Even without infinite
> recursion, they're just as nonsensical as ever.
>=20
> [...]
>=20

Ok. will redo it.