From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23750 invoked by alias); 22 Sep 2004 14:35:37 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 23742 invoked from network); 22 Sep 2004 14:35:35 -0000 Received: from unknown (HELO duke.cs.duke.edu) (152.3.140.1) by sourceware.org with SMTP; 22 Sep 2004 14:35:35 -0000 Received: from minie.cs.duke.edu (minie.cs.duke.edu [152.3.140.24]) by duke.cs.duke.edu (8.12.10/8.12.10) with ESMTP id i8MEZZJt013771 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 22 Sep 2004 10:35:35 -0400 (EDT) Received: (from trt@localhost) by minie.cs.duke.edu (8.12.10/8.12.10/Submit) id i8MEZYX0009371 for gcc@gcc.gnu.org; Wed, 22 Sep 2004 10:35:34 -0400 (EDT) From: "Thomas R. Truscott" Message-Id: <200409221435.i8MEZYX0009371@minie.cs.duke.edu> Subject: RE: Warning flags for unsigned operations (unsafe) To: gcc@gcc.gnu.org Date: Wed, 22 Sep 2004 15:38:00 -0000 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-SW-Source: 2004-09/txt/msg01279.txt.bz2 > I couldn't find out if gcc had a > warning flag for unsigned operation. For example, even the linear > interpolation on [a,b] can be tricky to code: > > c = a + t * (b - a); //unsafe Not for this situation. I think a warning would be appropriate when an unsigned quantity involving subtraction is widened or converted to double. > Your code has a design flaw and is not valid. Uh, that misses the whole point of warning messages, doesn't it? Tom Truscott