From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-368309-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 5019 invoked by alias); 22 Sep 2011 00:16:49 -0000
Received: (qmail 5002 invoked by uid 22791); 22 Sep 2011 00:16:44 -0000
X-SWARE-Spam-Status: No, hits=-2.9 required=5.0	tests=ALL_TRUSTED,AWL,BAYES_00
X-Spam-Check-By: sourceware.org
Received: from localhost (HELO gcc.gnu.org) (127.0.0.1)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 22 Sep 2011 00:16:31 +0000
From: "rui.maciel at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/50476] New: Warn of pointer set to object whose lifetime is limited
Date: Thu, 22 Sep 2011 01:25:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c
X-Bugzilla-Keywords:
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: rui.maciel at gmail dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-50476-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2011-09/txt/msg01486.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50476

             Bug #: 50476
           Summary: Warn of pointer set to object whose lifetime is
                    limited
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: rui.maciel@gmail.com


Consider the following code:

<code>
#include <stdio.h>

int *x = NULL;

void f(void)
{
        int y = 1;

        x = &y;
}


int main(void)
{
        f();

        printf("int: %d\n", *x);

        return 0;
}

</code>

Function f() assigns a global pointer to a local object, so that the global
pointer refers to the local object's address even when the object's lifetime
ends.  This represents undefined behaviour, and therefore can be a potential
source of problems.  It would be great if gcc at least threw a warning
informing the user of this problem, similar to how Bug 14156 handles it's use
case.