Hello, I observed this weekend, that permutation_iterator cannot provide compatible conversions, in constrast to all other iterators. The problem is due to access right violations in the "conversion" pseudo copy c'tor: template permutation_iterator( permutation_iterator const& r , typename enable_if_convertible::type* = 0 , typename enable_if_convertible::type* = 0 ) : super_t(r.base()), m_elt_iter(r.m_elt_iter) {} This c'tor cannot be instantiated successfully, even if SFINAE has allowed that: The private member m_elt_iter cannot be accessed from another permutation_iterator and the result is a compile error. One should either provide friendship to permutation_iterator or the private member should be readable via a public member function to fix this. I have provided a corresponding bug report http://sourceforge.net/tracker/index.php?func=detail&aid=1530999&group_id=7586&atid=107586 It would be very nice, if that fix could go into boost 1.34! Many thanks and Greetings from Bremen, Daniel Krügler