Bug 973 – [std.date] DST (daylight savings time) not applied in southern hemisphere

The function DaylightSavingTA in Phobos' std.date module always returns 0 when run in a southern hemisphere locale, under Windows. This is because it implicitly assumes that daylight saving time ends at a later date (in the year) than it begins. This is only true for the northern hemisphere. In Australia, for example, DST typically begins in October and ends in March. The assumption is on line 803 of phobos/std/date.d: if (td <= dt && dt <= ts) // line 803 containing incorrect assumption { t = -tzi.DaylightBias * (60 * TicksPerSecond); //printf("DST is in effect, %d\n", t); } else { //printf("no DST\n"); } Possible (but untested) fix: if ((td <= dt && dt <= ts) || td <= ts || dt >= td) { t = -tzi.DaylightBias * (60 * TicksPerSecond); //printf("DST is in effect, %d\n", t); } else { //printf("no DST\n"); }

Oops - typo in my suggested fix, plus it would actually break northern hemisphere usage. Here's a better one: if ((td <= dt && dt <= ts) || (ts > td && (td <= dt || dt <= ts))) I /think/ that's correct. Having trouble with all these 2-letter variable names. *g*

(In reply to comment #1) Doh. Had a comparison sign the wrong way around. Sorry about this! Third time lucky? if ((td <= dt && dt <= ts) || (ts < td && (dt <= ts || td <= dt)))

Probably fixed in datetime. Close it?

It's a D1 bug, since std.date is still around in D1.

It's unlikely this D1 issue will get worked on, if anyone plans to work on it feel free to reopen.