public inbox for gcc-help@gcc.gnu.org
 help / color / mirror / Atom feed
From: "Lars Gullik Bjønnes" <larsbj@gullik.org>
To: gcc-help@gcc.gnu.org
Subject: False positive from -Warray-bounds?
Date: Thu, 29 Dec 2011 22:02:00 -0000	[thread overview]
Message-ID: <CAOYg4AyWZLaxMcvcj9NewAq8XjxXpsTbr7mVOwZ+a_-DSK4eqA@mail.gmail.com> (raw)

I have this code:

--------------
unsigned int f(unsigned int value)
{
    unsigned int i = (value & 0xffff);
    return (i == 0xffff ? 0xffffffff : i);
}


static int *arr1[10];

void t(unsigned int s)
{
    arr1[f(s)] = 0;
    arr1[f(s)] = 0;
}
------------------


When compiled with 'gcc -Wall -Wextra -c' I get a warning about
"subscript is above array bounds".
Shouldn't the -Warray-bounds only warn if will _always_ be out-of-bounds?

Is this a false positive, or is there something that I am completely missing?

I see this with gcc from trunk (some days ago), and with redhat gcc 4.6.2-1.

-- 
        Lgb

             reply	other threads:[~2011-12-29 21:38 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-29 22:02 Lars Gullik Bjønnes [this message]
2011-12-29 22:45 ` Ian Lance Taylor
2011-12-29 23:03   ` Lars Gullik Bjønnes
2011-12-29 23:57     ` Ian Lance Taylor
2011-12-30  0:16       ` Vincent Lefevre
2011-12-30  0:21         ` Vincent Lefevre
2011-12-30  0:38         ` Ian Lance Taylor
2011-12-30  5:00           ` Vincent Lefevre
2011-12-30  8:29             ` Ian Lance Taylor
2011-12-30 12:08               ` David Brown
2011-12-30 19:44                 ` Vincent Lefevre
2011-12-29 23:24   ` Vincent Lefevre
2011-12-30  0:19     ` Ian Lance Taylor
2011-12-29 23:17 ` Vincent Lefevre

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=CAOYg4AyWZLaxMcvcj9NewAq8XjxXpsTbr7mVOwZ+a_-DSK4eqA@mail.gmail.com \
    --to=larsbj@gullik.org \
    --cc=gcc-help@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).