This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

Re: unsigned / double propagation weirdness?

From: Robert Dewar <dewar at gnat dot com>
To: Giovanni Bajo <giovannibajo at libero dot it>
Cc: Andrew Pinski <pinskia at physics dot uc dot edu>,Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>,gcc at gcc dot gnu dot org
Date: Mon, 23 Feb 2004 12:24:03 -0500
Subject: Re: unsigned / double propagation weirdness?
References: <403A116B.6080300@tat.physik.uni-tuebingen.de> <D9E4AE53-6617-11D8-BE9E-000393A6D2F2@physics.uc.edu> <403A2EFC.8070304@gnat.com> <38c701c3fa2d$79e7e9e0$aa422597@bagio>

Giovanni Bajo wrote:

you certainly don't want to regard the use of unary
minus on unsigned as something you warn about.

What's the rationale for this? I know that other compilers do implement this
warning and I indeed found it useful in the past.

To me, unary minus on unsigned is both useful, and has a clear and expected meaning (take the twos complement). I would find it most irritating to get warnings on this. If it is really the case that many/most C programmers are bamboozled by this standard usage in the language, perhaps there is an argument for a warning that can be turned on, but I certainly would not want to see this in -Wall.

Follow-Ups:
- Re: unsigned / double propagation weirdness?
  - From: Richard Guenther

References:
- unsigned / double propagation weirdness?
  - From: Richard Guenther
- Re: unsigned / double propagation weirdness?
  - From: Andrew Pinski
- Re: unsigned / double propagation weirdness?
  - From: Robert Dewar
- Re: unsigned / double propagation weirdness?
  - From: Giovanni Bajo

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]