From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-prs-return-35565-listarch-gcc-prs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 14290 invoked by alias); 14 May 2003 15:46:01 -0000
Mailing-List: contact gcc-prs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Archive: <http://gcc.gnu.org/ml/gcc-prs/>
List-Post: <mailto:gcc-prs@gcc.gnu.org>
List-Help: <mailto:gcc-prs-help@gcc.gnu.org>
Sender: gcc-prs-owner@gcc.gnu.org
Received: (qmail 14219 invoked by uid 71); 14 May 2003 15:46:01 -0000
Resent-Date: 14 May 2003 15:46:01 -0000
Resent-Message-ID: <20030514154601.14218.qmail@sources.redhat.com>
Resent-From: gcc-gnats@gcc.gnu.org (GNATS Filer)
Resent-Cc: gcc-prs@gcc.gnu.org, gcc-bugs@gcc.gnu.org,
  Sylvain.Pion@mpi-sb.mpg.de
Resent-Reply-To: gcc-gnats@gcc.gnu.org, Sylvain.Pion@mpi-sb.mpg.de
Received: (qmail 30745 invoked by uid 48); 14 May 2003 15:38:40 -0000
Message-Id: <20030514153840.30740.qmail@sources.redhat.com>
Date: Wed, 14 May 2003 15:46:00 -0000
From: Sylvain.Pion@mpi-sb.mpg.de
Reply-To: Sylvain.Pion@mpi-sb.mpg.de
To: gcc-gnats@gcc.gnu.org
Cc: Sylvain.Pion@mpi-sb.mpg.de
X-Send-Pr-Version: gnatsweb-2.9.3 (1.1.1.1.2.31)
X-GNATS-Notify: Sylvain.Pion@mpi-sb.mpg.de
Subject: libstdc++/10783: std::vector::reverse_iterator  could be smaller
X-SW-Source: 2003-05/txt/msg01653.txt.bz2
List-Id: <gcc-prs.sourceware.org>


>Number:         10783
>Category:       libstdc++
>Synopsis:       std::vector::reverse_iterator  could be smaller
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          pessimizes-code
>Submitter-Id:   net
>Arrival-Date:   Wed May 14 15:46:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Sylvain Pion
>Release:        3.2, 3.3, 3.4 (2.95 doesn't have the problem, I don't have 3.[01])
>Organization:
>Environment:
Reading specs from ./GCC/Linux-3.2/bin/../lib/gcc-lib/i686-pc-linux-gnu/3.2.3/specs
Configured with: ../gcc-3.2/configure --prefix=/home/spion/GCC/Linux-3.2 --enable-languages=c++
Thread model: posix
gcc version 3.2.3
>Description:
On my 32bit machine,
sizeof(std::vector<>::reverse_iterator) is 8.
Similarly for std::vector<>::const_reverse_iterator.

All other iterators from the STL containers (except deque)
have sizeof 4.

I believe it could be made also 4 bytes if the empty base class optimization applied, but it seems it doesn't.
Is it because there are 2 derivations from the same iterator<...> class ?  Is there a way to fix it ?
>How-To-Repeat:
#include <iostream>
#include <vector>
int main() {
  typedef std::vector<int> V;
  std::cout << "sizeof(iterator) = " << sizeof(V::iterator) << std::endl;
  std::cout << "sizeof(reverse_iterator) = " << sizeof(V::reverse_iterator) << std::endl;
}
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: