[Boost-bugs] [Boost C++ Libraries] #9072: `iterator_range` does not accept iterators having "reference to function type" as `reference` nested type

Subject: [Boost-bugs] [Boost C++ Libraries] #9072: `iterator_range` does not accept iterators having "reference to function type" as `reference` nested type
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2013-08-31 12:49:15

#9072: `iterator_range` does not accept iterators having "reference to function
type" as `reference` nested type
-------------------------------------+------------------------------
 Reporter:  michel                   |      Owner:  jeffrey.hellrung
     Type:  Patches                  |     Status:  new
Milestone:  To Be Determined         |  Component:  iterator
  Version:  Boost Development Trunk  |   Severity:  Problem
 Keywords:                           |
-------------------------------------+------------------------------
 This is a very minor thing.

 This code works:
 {{{
 #include <iostream>
 #include <boost/iterator/transform_iterator.hpp>

 void zero() { std::cout << "zero" << std::endl; }
 void non_zero() { std::cout << "non-zero" << std::endl; }

 typedef void function_type();
 function_type& f(int i)
 {
     if (i == 0) {
         return zero;
     }
     else {
         return non_zero;
     }
 }

 int main(int argc, char* argv[])
 {
     int ar[2] = {0, 1};

     typedef boost::transform_iterator<function_type&(*)(int), int*>
 iterator;

     iterator it_0 = boost::make_transform_iterator(ar + 0, f);
     iterator it_1 = boost::make_transform_iterator(ar + 1, f);

     (*it_0)();
     (*it_1)();

     return 0;
 }
 }}}

 But this code does not compile:
 {{{
 #include <iostream>
 #include <boost/iterator/transform_iterator.hpp>
 #include <boost/range/iterator_range.hpp>

 void zero() { std::cout << "zero" << std::endl; }
 void non_zero() { std::cout << "non-zero" << std::endl; }

 typedef void function_type();
 function_type& f(int i)
 {
     if (i == 0) {
         return zero;
     }
     else {
         return non_zero;
     }
 }

 int main(int argc, char* argv[])
 {
     int ar[2] = {0, 1};

     typedef boost::transform_iterator<function_type&(*)(int), int*>
 iterator;
     typedef boost::iterator_range<iterator> range;

     range rng(
         boost::make_transform_iterator(ar, f)
       , boost::make_transform_iterator(ar + 2, f)
     );

     rng[0]();
     rng[1]();

     return 0;
 }
 }}}

 This is because `iterator_range` does not accept iterators having
 "reference to function type" as `reference` nested type.

 Patch attached. Tested on gcc-4.7 and clang trunk.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/9072>
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