[Boost-bugs] [Boost C++ Libraries] #7680: Poor choice of difference_type for zip_iterator

Subject: [Boost-bugs] [Boost C++ Libraries] #7680: Poor choice of difference_type for zip_iterator
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-11-11 04:37:07

#7680: Poor choice of difference_type for zip_iterator
------------------------------------+---------------------------------------
 Reporter:  matthias_berndt@…       |       Owner:  dave    
     Type:  Bugs                    |      Status:  new     
Milestone:  To Be Determined        |   Component:  iterator
  Version:  Boost 1.52.0            |    Severity:  Problem 
 Keywords:                          |  
------------------------------------+---------------------------------------
 Hi,

 the following program results in an integer overflow on my system (Linux
 g++ 4.7.2):
 {{{#!c++
 #include <boost/iterator/zip_iterator.hpp>
 #include <boost/iterator/counting_iterator.hpp>
 #include <boost/tuple/tuple.hpp>
 #include <iostream>
 int main() {
   boost::counting_iterator<unsigned short> i1(0);
   boost::counting_iterator<unsigned long long> i2(0);
   auto i3 = boost::make_zip_iterator(boost::make_tuple(i1, i2));
   i3 += 3221225472u;
   std::cout << boost::get<1>(*i3) << '\n';
 }
 }}}
 It prints 18446744072635809792, but I'd expect it to print 3221225472.
 boost::zip_iterator seems to use the first underlying iterator's
 difference_type as its own difference_type, which isn't necessarily the
 right choice.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/7680>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.