In date_time/string_parse_tree.hpp, there is the following code: template<typename charT> struct string_parse_tree { #if BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x581) ) typedef std::multimap<charT, string_parse_tree< charT> > ptree_coll; #else typedef std::multimap<charT, string_parse_tree > ptree_coll; #endif ... ptree_coll m_next_chars; ... }; This code instantiates STL container on an incomplete type. According to section 17.4.3.6 of the C++ Standard, the implementation does not have to support this. The Rogue Wave library v2.2 and higher does not allow this for associative containers (it does allow this for sequences). For example, compiling a tiny program below on HP-UX results in an "incomplete type is not allowed" error. This is what breaks date_time library tests on HP-UX. The Rogue Wave library v2.0, which is the C++ standard library on Tru64, allows this, as well as gnu libstdc++, Dinkumware library and STLport. It may explain why this issue has not been noticed before. Boris Gubenko ---%<--- #include <map> struct string_parse_tree { typedef std::multimap<char, string_parse_tree> ptree_coll; ptree_coll m_next_chars; }; string_parse_tree x; --->%---