public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "rakdver at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/27214] The C frontend introduces undefined pointer overflow
Date: Wed, 19 Apr 2006 16:32:00 -0000	[thread overview]
Message-ID: <20060419163240.2057.qmail@sourceware.org> (raw)
In-Reply-To: <bug-27214-10053@http.gcc.gnu.org/bugzilla/>



------- Comment #6 from rakdver at gcc dot gnu dot org  2006-04-19 16:32 -------
I do not think this PR is invalid:

int a[100];
int *p = &a[50];

p - 1 is well defined, and points to 50 - 1 th element of a, as standard
specifies
p + (-1) is also well defined, and points to 50 + (-1) th element, again
according to standard.
p + (unsigned) -1 is undefined, as there is no 50 + 4294967295 th element in a
(the standard specifies that there cannot be any overflow in the computation).

Andrew, please do not mark PRs as invalid until the people involved in the
discussion do not agree on the common interpretation of the standard.


-- 

rakdver at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27214


  parent reply	other threads:[~2006-04-19 16:32 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-04-19 11:44 [Bug c/27214] New: " rguenth at gcc dot gnu dot org
2006-04-19 15:06 ` [Bug c/27214] " pinskia at gcc dot gnu dot org
2006-04-19 15:13 ` rguenth at gcc dot gnu dot org
2006-04-19 15:22 ` pinskia at gcc dot gnu dot org
2006-04-19 15:31 ` rguenth at gcc dot gnu dot org
2006-04-19 15:34 ` pinskia at gcc dot gnu dot org
2006-04-19 16:32 ` rakdver at gcc dot gnu dot org [this message]
2006-04-19 17:15 ` joseph at codesourcery dot com
2006-05-05  9:23 ` pinskia at gcc dot gnu dot org
2007-12-11  0:46 ` pinskia at gcc dot gnu dot org
2008-01-03 16:25 ` rguenth at gcc dot gnu dot org
     [not found] <bug-27214-4@http.gcc.gnu.org/bugzilla/>
2012-05-06  4:23 ` bugdal at aerifal dot cx
2012-05-07  9:21 ` rguenth at gcc dot gnu.org
2021-03-25 14:11 ` rguenth at gcc dot gnu.org

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20060419163240.2057.qmail@sourceware.org \
    --to=gcc-bugzilla@gcc.gnu.org \
    --cc=gcc-bugs@gcc.gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).