Using g++ 3.4.4 (on 64-bit Linux) my source won't compile gregorian_calendar_base<>::is_leap_year. The problem stems from the '%' operator with mixed types. My code includes (unfortunately) a class that has arithmetic operators with most of the integer and floating-point types on the left, constructors from those types, and conversion operators to those types. The compiler finds the ambiguity and can't decide between the built-in operator%(int, int) and all the other possibilities with my nasty class's '%' operators. I fixed the problem in gregorian_calendar.ipp by casting 'year' to 'int' in 'is_leap_year'. This is the diff: diff -u -r1.1.1.1 gregorian_calendar.ipp --- boost/date_time/gregorian_calendar.ipp 27 Apr 2007 17:10:19 -0000 1.1.1.1 +++ boost/date_time/gregorian_calendar.ipp 2 May 2007 13:59:31 -0000 @@ -164,7 +164,7 @@ gregorian_calendar_base<ymd_type_,date_int_type_>::is_leap_year(year_type year) { //divisible by 4, not if divisible by 100, but true if divisible by 400 - return (!(year % 4)) && ((year % 100) || (!(year % 400))); + return (!(static_cast<int>(year) % 4)) && ((static_cast<int>(year) % 100) || (!(static_cast<int>(year) % 400))); } //! Calculate the last day of the month We have had this problem since starting to use the date_time library in 1.32.0. The user was not interested in reporting it, and I hoped someone else would report it. However, that has not happened, so here it is. It would be nice to see it get into the next release. BTW, we had some other similar problems, which we fixed by changing a few casts, but they have not reproduced themselves in 1.34.0 beta. Perhaps they were only problems for some other compiler, which we are no longer using. -- Dick Hadsell 914-259-6320 Fax: 914-259-6499 Reply-to: hadsell@blueskystudios.com Blue Sky Studios http://www.blueskystudios.com 44 South Broadway, White Plains, NY 10601