strided breaks on impure traversal tags

[anonymous]

From ​http://stackoverflow.com/questions/28280553/boostadaptorsstrided-cannot-be-used-after-boostadaptorstransformed

[...]/boost/1.57.0/include/boost/range/iterator_range_core.hpp:216:20: error: no matching function for call to ‘boost::range_detail::strided_iterator<boost::iterators::transform_iterator<TrivialTrafo, __gnu_cxx::__normal_iterator<int*, std::vector<int> >, boost::iterators::use_default, boost::iterators::use_default>, boost::iterators::detail::iterator_category_with_traversal<std::input_iterator_tag, boost::iterators::random_access_traversal_tag> >::strided_iterator(boost::range_detail::strided_iterator<boost::iterators::transform_iterator<TrivialTrafo, __gnu_cxx::__normal_iterator<int*, std::vector<int> >, boost::iterators::use_default, boost::iterators::use_default>, boost::iterators::random_access_traversal_tag>&)’

, m_End(End)

Problem is that make_begin_strided_iterator et al coerce the returned iterator traversal category/tag to a pure traversal tag, which doesn't necessarily agree with the Category passed to iterator_range for the base type. Fix is to use iterators::pure_iterator_traversal.

[Edward Catmur <ed@…>]

Fix:

--- a/include/boost/range/adaptor/strided.hpp +++ b/include/boost/range/adaptor/strided.hpp @@ -603,7 +603,7 @@ namespace boost

template<

class Rng, class Category =

• typename iterator_traversal<

+ typename iterators::pure_iterator_traversal<

typename range_iterator<Rng>::type

::type

[Edward Catmur <ed@…>]

Let's try that again.

Fix:

--- a/include/boost/range/adaptor/strided.hpp
+++ b/include/boost/range/adaptor/strided.hpp
@@ -603,7 +603,7 @@ namespace boost
         template<
             class Rng,
             class Category =
-                typename iterator_traversal<
+                typename iterators::pure_iterator_traversal<
                     typename range_iterator<Rng>::type
                 >::type
         >

[Neil Groves]

Thank you very much for your excellent ticket. This was superb. I've applied the change to the develop branch. Once this cycles a few times through the tests I shall merge to master ready for the 1.58 release.