Hello, It seems to me the concept checking performed by Boost.Range for the SinglePassIterator concept is too strict. In boost/range/concepts.hpp, SinglePassIteratorConcept checks for the following usage (line 157 in trunk): BOOST_DEDUCED_TYPENAME boost::detail::iterator_traits<Iterator>::reference r1(*i); This requires that the return type of operator* be convertible to the iterator's reference type. However, looking at the specification for single pass iterators [1], I don't see any requirement that the return type of operator* be convertible to the reference type - it just needs to be convertible to the value type. An example of an iterator for which the return type of operator* is not convertible to the iterator's reference type is std::istreambuf_iterator<charT>, whose reference type is charT&, but the return type of its operator* is charT. (Both of these are specified explicitly in section 24.5.3 of the C++03 standard.) As a result, code such as the following fails to compile with GCC or MSVC in C++03 mode: #include <boost/range/concepts.hpp> #include <boost/range/iterator_range.hpp> #include <iterator> #include <istream> int main() { BOOST_CONCEPT_ASSERT (( boost::SinglePassRangeConcept< boost::iterator_range< std::istreambuf_iterator<char> > > )); } (In C++11, things changed - a requirement was added that the return type of operator* be the same as the iterator's reference type, and correspondingly std::istreambuf_iterator<charT>'s reference type was changed to be charT). What can be done about this? Regards, Nate [1] http://www.boost.org/doc/libs/1_48_0/libs/iterator/doc/new-iter-concepts.htm...