From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-359519-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 3384 invoked by alias); 12 Jun 2011 15:16:29 -0000
Received: (qmail 3375 invoked by uid 22791); 12 Jun 2011 15:16:28 -0000
X-SWARE-Spam-Status: No, hits=-2.7 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; Sun, 12 Jun 2011 15:16:15 +0000
From: "pogonyshev at gmx dot net" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/49384] New: istringstream::tellg at the end of string gives a wrong result
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: pogonyshev at gmx dot net
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-49384-4@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
Date: Sun, 12 Jun 2011 15:16:00 -0000
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: 2011-06/txt/msg01045.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49384

           Summary: istringstream::tellg at the end of string gives a
                    wrong result
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: pogonyshev@gmx.net


According to the specification:

    Returns: After constructing a sentry object, if fail() != false, returns
pos_type(-1) to indicate failure. Otherwise, returns rdbuf()->pubseekoff(0,
cur, in).

Tested with geordi:

    { istringstream x ("lol"); string y; x >> y; cout << y, x.fail (); cout,
x.tellg (); cout, x.rdbuf ()->pubseekoff (0, ios::cur, ios::in); }

Output:
    lol, false, -1, 3

Note that fail() returns 'false', yet tellg() gives -1.  Also, I tested the
standard-prescribed return value above: it is 3 as expected, suggesting that
tellg() tests eof() rather than fail() to decide if return -1 or not.

This used to work as standardized before (I believe with 4.6.0 too, though not
sure).  I noticed after my program stopped working correctly without any
changes, just compiler upgrade.