From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-return-116362-listarch-gcc=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 1758 invoked by alias); 28 Jun 2005 03:49:08 -0000
Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Archive: <http://gcc.gnu.org/ml/gcc/>
List-Post: <mailto:gcc@gcc.gnu.org>
List-Help: <http://gcc.gnu.org/ml/>
Sender: gcc-owner@gcc.gnu.org
Received: (qmail 1745 invoked by uid 22791); 28 Jun 2005 03:49:03 -0000
Received: from smtp-102-tuesday.noc.nerim.net (HELO mallaury.noc.nerim.net) (62.4.17.102)
    by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Tue, 28 Jun 2005 03:49:03 +0000
Received: from uniton.integrable-solutions.net (gdr.net1.nerim.net [62.212.99.186])
	by mallaury.noc.nerim.net (Postfix) with ESMTP id 5FE0262D06;
	Tue, 28 Jun 2005 05:48:57 +0200 (CEST)
Received: from uniton.integrable-solutions.net (localhost [127.0.0.1])
	by uniton.integrable-solutions.net (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id j5S3mPKY001550;
	Tue, 28 Jun 2005 05:48:25 +0200
Received: (from gdr@localhost)
	by uniton.integrable-solutions.net (8.12.10/8.12.10/Submit) id j5S3mPqM001549;
	Tue, 28 Jun 2005 05:48:25 +0200
To: Mark Mitchell <mark@codesourcery.com>
Cc: Michael Veksler <VEKSLER@il.ibm.com>, Paul Koning <pkoning@equallogic.com>,
        gcc@gcc.gnu.org, nathan@codesourcery.com
Subject: Re: Do C++ signed types have modulo semantics?
References: <OFF89CA957.1E322A19-ONC225702D.0052A8AF-C225702D.00546B33@il.ibm.com>
	<42C0BE8C.4040308@codesourcery.com>
From: Gabriel Dos Reis <gdr@integrable-solutions.net>
In-Reply-To: <42C0BE8C.4040308@codesourcery.com>
Date: Tue, 28 Jun 2005 03:49:00 -0000
Message-ID: <m3ll4vjg52.fsf@uniton.integrable-solutions.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-SW-Source: 2005-06/txt/msg01073.txt.bz2

Mark Mitchell <mark@codesourcery.com> writes:

| Michael Veksler wrote:
| 
| >> Most programmers "know" that arithmetic is modulo wordsize.  And those few
| >>who know the right answer (only unsigned arithmetic is modulo) will
| >>from time to time slip up and omit the "unsigned" keyword in their
| >>declarations.
| 
| I agree.
| 
| Although the standard clearly makes signed overflow undefined, I think
| it would be better if GCC defined it to be modulo arithmetic.  The
| degree to which that would result in inferior code seems likely to be
| somewhat small, and the amount of user confusion we would eliminate,
| and the number of programs that would not break with GCC, even though
| they work with other compilers, seems likely to be high.

Amen.

-- Gaby