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Date: Wed, 04 Dec 2002 10:26:00 -0000
Message-ID: <20021204182601.17574.qmail@sources.redhat.com>
To: paolo@gcc.gnu.org
Cc: gcc-prs@gcc.gnu.org,
From: Joe Buck <jbuck@synopsys.com>
Subject: Re: libstdc++/8780: std::vector iterators not recognized as pointers
 by templates in certain cases
Reply-To: Joe Buck <jbuck@synopsys.com>
X-SW-Source: 2002-12/txt/msg00226.txt.bz2
List-Id: <gcc-prs.sourceware.org>

The following reply was made to PR libstdc++/8780; it has been noted by GNATS.

From: Joe Buck <jbuck@synopsys.com>
To: gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org, johnb@stl.sarov.ru,
   gcc-bugs@gcc.gnu.org, paolo@gcc.gnu.org
Cc:  
Subject: Re: libstdc++/8780: std::vector iterators not recognized as pointers
 by templates in certain cases
Date: Wed, 04 Dec 2002 10:21:03 -0800

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8780
 
 Thanks for the report, but this is not a bug.
 
 Any code that assumes that a vector<T>::iterator is a pointer is 
 non-portable
 and will break on many C++ implementations (including debug implementations,
 which use extra fields in the iterator to detect dereferencing of out of 
 range
 iterators).
 
 
 If you have code that makes such assumptions, then for cases where you know
 that the iterator is not pointing to vec.end(), the construct &*iter 
 will give
 a valid pointer to the data (and you may portably assume that the data are
 stored contiguously in the vector).  A portable one-past-the-end pointer is
 1+&vec.back() .