From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-326052-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 4573 invoked by alias); 26 Jul 2010 16:11:42 -0000
Received: (qmail 4488 invoked by uid 48); 26 Jul 2010 16:11:23 -0000
Date: Mon, 26 Jul 2010 16:11:00 -0000
Subject: [Bug tree-optimization/45085]  New: incorrect -Wuninitialized warning
X-Bugzilla-Reason: CC
Message-ID: <bug-45085-360@http.gcc.gnu.org/bugzilla/>
Reply-To: gcc-bugzilla@gcc.gnu.org
To: gcc-bugs@gcc.gnu.org
From: "tromey at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
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: 2010-07/txt/msg02884.txt.bz2

I'm using a relatively recent svn trunk gcc on an x86 Fedora 13 machine.
I'm trying to compile gdb with it.  I got this error:

../../archer/gdb/remote.c: In function ‘remote_wait’:
../../archer/gdb/remote.c:5561:10: error: ‘event_ptid.tid’ may be used
uninitialized in this function [-Werror=uninitialized]
../../archer/gdb/remote.c:5561:10: error: ‘event_ptid.lwp’ may be used
uninitialized in this function [-Werror=uninitialized]
../../archer/gdb/remote.c:5561:10: error: ‘event_ptid.pid’ may be used
uninitialized in this function [-Werror=uninitialized]
cc1: all warnings being treated as errors

But the body of remote_wait is simple:

{
  ptid_t event_ptid;

  if (non_stop)
    event_ptid = remote_wait_ns (ptid, status, options);
  else
    event_ptid = remote_wait_as (ptid, status, options);

  if (target_can_async_p ())
    {
      /* If there are are events left in the queue tell the event loop
         to return here.  */
      if (stop_reply_queue)
        mark_async_event_handler (remote_async_inferior_event_token);
    }

  return event_ptid;
}

I thought perhaps that inlining was causing a problem (in which case this
error message is quite confusing, since it would point to the wrong function).

However, I added this:

  memset (&event_ptid, 0, sizeof (event_ptid));

... to the function before the "if", and the error went away.
So, I think this is a gcc bug.

I will attach the .i file.


-- 
           Summary: incorrect -Wuninitialized warning
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tromey at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45085