From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-patches-return-437036-listarch-gcc-patches=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 37747 invoked by alias); 27 Sep 2016 14:11:07 -0000
Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-patches.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>
List-Post: <mailto:gcc-patches@gcc.gnu.org>
List-Help: <mailto:gcc-patches-help@gcc.gnu.org>
Sender: gcc-patches-owner@gcc.gnu.org
Received: (qmail 37705 invoked by uid 89); 27 Sep 2016 14:11:06 -0000
Authentication-Results: sourceware.org; auth=none
X-Virus-Found: No
X-Spam-SWARE-Status: No, score=-3.8 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy=
X-HELO: albireo.enyo.de
Received: from albireo.enyo.de (HELO albireo.enyo.de) (5.158.152.32) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 27 Sep 2016 14:11:04 +0000
Received: from [172.17.203.2] (helo=deneb.enyo.de)	by albireo.enyo.de with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)	id 1bot61-0005qO-QE; Tue, 27 Sep 2016 16:10:57 +0200
Received: from fw by deneb.enyo.de with local (Exim 4.84_2)	(envelope-from <fw@deneb.enyo.de>)	id 1bot61-00086G-LO; Tue, 27 Sep 2016 16:10:57 +0200
From: Florian Weimer <fw@deneb.enyo.de>
To: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: Jason Merrill <jason@redhat.com>,  "gcc-patches\@gcc.gnu.org" <gcc-patches@gcc.gnu.org>,  Jeff Law	<law@redhat.com>
Subject: Re: [PATCH] Make -Wint-in-bool-context warn on suspicious shift ops
References: <AM4PR0701MB2162CF4DE9EAAFFE605F4BB0E4CA0@AM4PR0701MB2162.eurprd07.prod.outlook.com>	<CADzB+2mYhkUgYHcJM9+f15psM=7GyasK5Af56A1W9cjXYFsmHQ@mail.gmail.com>	<87shslv769.fsf@mid.deneb.enyo.de>	<HE1PR0701MB216982AD7458FB1E5244360AE4CC0@HE1PR0701MB2169.eurprd07.prod.outlook.com>
Date: Tue, 27 Sep 2016 14:34:00 -0000
In-Reply-To: <HE1PR0701MB216982AD7458FB1E5244360AE4CC0@HE1PR0701MB2169.eurprd07.prod.outlook.com>	(Bernd Edlinger's message of "Tue, 27 Sep 2016 13:53:57 +0000")
Message-ID: <87fuol77ri.fsf@mid.deneb.enyo.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
X-IsSubscribed: yes
X-SW-Source: 2016-09/txt/msg01999.txt.bz2

* Bernd Edlinger:

>> =E2=80=9C0 << 0=E2=80=9D is used in a similar context, to create a zero =
constant for a
>> multi-bit subfield of an integer.
>>
>> This example comes from GDB, in bfd/elf64-alpha.c:
>>
>> |   insn =3D INSN_ADDQ | (16 << 21) | (0 << 16) | (0 << 0);
>>
>
> Of course that is not a boolean context, and will not get a warning.
>
> Question is if "if (1 << 0)" is possibly a miss-spelled "if (1 < 0)".
>
> Maybe 1 and 0 come from macro expansion....

But what's the intent of treating 1 << 0 and 0 << 0 differently in the
patch, then?