id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
8011	iterator_range::size() is not SFINAE-friendly	Jonathan Wakely <jwakely.boost@…>	Neil Groves	"iterator_range<I>::size() is always defined, but fails a static assertion if I is not a random access iterator.  This means it's not possible to use SFINAE To detect whether r.size() is valid.

By moving the size() member to a new base type like the one below (and updating iterator_range to use this->m_Begin and this->m_End everywhere) the function will only be present when it can actually be used:

{{{
        template<class IteratorT, class CategoryT
                 = typename std::iterator_traits<IteratorT>::iterator_category>
        class iterator_range_base
        {
        protected:
            template< class Iterator >
            iterator_range_base( Iterator Begin, Iterator End ) :
                m_Begin(Begin), m_End(End)
            {}

            // begin and end iterators
            IteratorT m_Begin;
            IteratorT m_End;
        };

        template<class IteratorT>
        class iterator_range_base<IteratorT, std::random_access_iterator_tag>
        {
        protected:
            template< class Iterator >
            iterator_range_base( Iterator Begin, Iterator End ) :
                m_Begin(Begin), m_End(End)
            {}

            typedef BOOST_DEDUCED_TYPENAME
                iterator_difference<IteratorT>::type difference_type;

            // begin and end iterators
            IteratorT m_Begin;
            IteratorT m_End;

        public:
            difference_type
            size() const { return m_End - m_Begin; }
        };
}}}

Also, the comment at the top of iterator_range_core.hpp says:

> Defines the \c iterator_class and related functions.

which should presumably say ""iterator_range class"" not ""iterator_class"""	Feature Requests	closed	To Be Determined	range	Boost 1.52.0	Problem	fixed