id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
1019,iterator_facade::pointer should be the return type of operator-> (DR 445),Niels Dekker,Dave Abrahams,"The definition of iterator_facade does not agree with the resolution of Standard Library Defect Report 445, submitted by David Abrahams, 2003-12-09. [[BR]]
http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#445

DR 445 is resolved within the current Draft of the Standard, as follows (Iterator traits, section 24.3.1):[[BR]]
'' iterator_traits<Iterator>::reference '' [[BR]]
'' iterator_traits<Iterator>::pointer '' [[BR]] 
''shall be defined as the iterator’s reference and pointer types, that is, for an iterator object a, the same type as the type of *a and a->, respectively.'' [[BR]]
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2135.pdf

On the other hand, iterator_facade::pointer is a raw pointer, while iterator_facade::operator->() returns operator_arrow_result::type, which may be a proxy.

To conform to the resolution of DR 445, iterator_facade::pointer should be defined as the return type of operator->(), e.g. (assuming that ''raw_pointer'' is the original raw pointer to the value_type):

{{{
  typedef typename operator_arrow_result<
      value_type
    , reference
    , raw_pointer
    >::type pointer;
}}}

More discussion about this issue:

comp.lang.c++.moderated, Sep 29 2005 [[BR]]
Re: iterator dereference requirements [[BR]]
http://groups.google.com/group/comp.lang.c++.moderated/msg/0f332bcd9a911526

comp.std.c++, March/April 2007 [[BR]]
What should std::InputIterator<T>::pointer be? [n2193 / n2083] [[BR]]
http://groups.google.com/groups/search?q=%22What+should+std%3A%3AInputIterator%3CT%3E%3A%3Apointer+be%3F%22

comp.std.c++, May 2007 [[BR]]
Testing new iterator concepts with ConceptGCC [[BR]]
http://groups.google.com/group/comp.std.c++/tree/browse_frm/thread/9c40ffc2f6394ca0/590e75dfbb993cf6

[I had some e-mail discussion with David Abrahams on this issue as well.]",Bugs,closed,Boost 1.36.0,iterator,Boost 1.34.0,Problem,fixed,,