Failure in posix_time_zone when specifying start date as Jn

[andrew.lang@…]

If you use the time zone specification "CST-2CDT,J365/00,J1/00" to create a boost::local_time::posix_time_zone, it fails with an exception.

The problem appears to be in boost\date_time\local_time\posix_time_zone.hpp, julian_no_leap(...). The conversion of the start date uses this loop which has a "less than or equal" clause:

while(sd >= calendar::end_of_month_day(year,sm)){

sd -= calendar::end_of_month_day(year,sm++);

}

sd is the converted start specifier (365 in this case); sm is the current month (initialized to 1). The loop continues until sd=0 and sm=13, at which point end_of_month_day() throws an exception.

Conversion of the end date uses an almost identical loop except that its while clause is "strictly less than":

while(ed > calendar::end_of_month_day(year,em)){

ed -= calendar::end_of_month_day(year,em++);

}

So the specifier "CST-2CDT,J1/00,J365/00" leaves ed=31 and em=12 as you would hope.

In fact any start specifier at the end of a month (J31, J59,...J334) will fail later because it will result in sd=0 which is outside the range of 1..31.

This code is identical in boost 1.52.0. The fix appears to be just to use "strictly less than" in both loops.