build failure of boost::date_time::string_parse_tree on HP-UX 11i v3

[kostrzewa@…]

OS: HP-UX B.11.31 U ia64
Compiler: aCC: HP C/aC++ B3910B A.06.15 [May 16 2007]

Test exposing the problem:

#include <boost/date_time/posix_time/posix_time_io.hpp>

boost::posix_time::time_input_facet const x("");

Compilation (aCC -c test.cc) output:

"/opt/aCC/include_std/utility", line 100: error #2070: incomplete type is not allowed
      second_type second;
                  ^
          detected during:
            instantiation of class "std::pair<_TypeT, _TypeU> [with _TypeT=const char, _TypeU=boost::date_time::string_parse_tree<char>]" at line 97 of "/opt/aCC/include_std/rw/tree"
            instantiation of class "__rw::__rw_rb_tree_node<_Alloc, _Val, _Key, _KeyOf> [with _Alloc=std::allocator<std::pair<const char, boost::date_time::string_parse_tree<char>>>, _Val=std::pair<const char, boost::date_time::string_parse_tree<char>>, _Key=char, _KeyOf=__rw::__select1st<std::pair<const char, boost::date_time::string_parse_tree<char>>, char>]" at line 282 of "/opt/aCC/include_std/rw/tree"
            instantiation of class "__rw::__rb_tree<_Key, _Val, _KeyOf, _Comp, _Alloc> [with _Key=char, _Val=std::pair<const char, boost::date_time::string_parse_tree<char>>, _KeyOf=__rw::__select1st<std::pair<const char, boost::date_time::string_parse_tree<char>>, char>, _Comp=std::less<char>, _Alloc=std::allocator<std::pair<const char, boost::date_time::string_parse_tree<char>>>]" at line 361 of "/opt/aCC/include_std/map"
            instantiation of class "std::multimap<_Key, _TypeT, _Compare, _Allocator> [with _Key=char, _TypeT=boost::date_time::string_parse_tree<char>, _Compare=std::less<char>, _Allocator=std::allocator<std::pair<const char, boost::date_time::string_parse_tree<char>>>]" at line 90 of "/opt/boost/include/boost/date_time/string_parse_tree.hpp"
            instantiation of class "boost::date_time::string_parse_tree<charT> [with charT=char]" at line 165 of "/opt/boost/include/boost/date_time/format_date_parser.hpp"
            instantiation of class "boost::date_time::format_date_parser<date_type, charT> [with date_type=boost::gregorian::date, charT=char]" at line 719 of "/opt/boost/include/boost/date_time/date_facet.hpp"
            instantiation of class "boost::date_time::date_input_facet<date_type, CharT, InItrT> [with date_type=boost::gregorian::date, CharT=char, InItrT=std::istreambuf_iterator<char, std::char_traits<char>>]" at line 657 of "/opt/boost/include/boost/date_time/time_facet.hpp"
            instantiation of class "boost::date_time::time_input_facet<time_type, CharT, InItrT> [with time_type=boost::posix_time::ptime, CharT=char, InItrT=std::istreambuf_iterator<char, std::char_traits<char>>]" at line 3 of "test.cc"