Patch for TW-13 in Taskwarrior

tw-13-2014-11-11.patch

$ Patch for daylight savings time
--- src/recur.cpp.orig
+++ src/recur.cpp
@@ -215,6 +215,7 @@ ISO8601d getNextRecurrence (ISO8601d& current, std::string& period)
   int m = current.month ();
   int d = current.day ();
   int y = current.year ();
+  ISO8601d recurrence_date;
 
   // Some periods are difficult, because they can be vague.
   if (period == "monthly" ||
@@ -240,8 +241,10 @@ ISO8601d getNextRecurrence (ISO8601d& current, std::string& period)
          if (dow == 5) days = 3;
     else if (dow == 6) days = 2;
     else               days = 1;
-
-    return current + (days * 86400);
+    // Shift current to midday to be safe of any DST changes, before calculating future date
+    recurrence_date = (ISO8601d (m, d, y) + 43200) + (days * 86400);
+    // Then set back to correct hour
+    return ISO8601d(recurrence_date.month (), recurrence_date.day (), recurrence_date.year ()) + 3600 * current.hour () + 60 * current.minute() + current.second ();
   }
 
   else if (Lexer::isDigit (period[0]) &&
@@ -379,3 +382,13 @@ ISO8601d getNextRecurrence (ISO8601d& current, std::string& period)
   secs = (time_t) p;
+  // if period is daily or greater, and a whole number of days, do the same as per weekdays
+  if ((secs >= 86400) && (secs % 86400 == 0))
+  {
+    // Shift current to midday to be safe of any DST changes, before calculating future date
+    recurrence_date = (ISO8601d (m, d, y) + 43200) + secs;
+    // Then set back to correct hour
+    return ISO8601d (recurrence_date.month (), recurrence_date.day (), recurrence_date.year ()) + 3600 * current.hour () + 60 * current.minute() + current.second ();
+    // Note: there are some edge cases where this still doesn't work for reasons unknown.
+    // However, it is safe for the default task times of midnight
+  }
   return current + secs;
 }

See original revision for more comments (that were in the git format patch). I keep this as a local patch for Pkgsrc now so I've removed all the original comments, etc. Current patch is for 2.5.0.