The latest incarnation of the HP compiler (version 6.0) looks to be a hugh improvement in respect to earlier versions. I'm looking into porting boost to HP aCC and I suggest to apply following (minor) patch (see attach). OK to commit this? toon cvs diff: Diffing . Index: is_convertible.hpp =================================================================== RCS file: /cvsroot/boost/boost/boost/type_traits/is_convertible.hpp,v retrieving revision 1.28 diff -u -r1.28 is_convertible.hpp --- is_convertible.hpp 4 Sep 2004 10:34:48 -0000 1.28 +++ is_convertible.hpp 14 Feb 2005 13:09:41 -0000 @@ -125,7 +125,7 @@ }; #elif (defined(__EDG_VERSION__) && (__EDG_VERSION__ >= 245) && !defined(__ICL)) \ - || defined(__IBMCPP__) + || defined(__IBMCPP__) || defined(__HP_aCC) // // This is *almost* an ideal world implementation as it doesn't rely // on undefined behaviour by passing UDT's through (...). cvs diff: Diffing detail