date_make_date() adds one hour during (US) DST, even in UTC

I managed to narrow down the problem somewhat. At least I hope I have, despite my non-existent PHP skills. date_make_date(...,'UTC', DATE_ISO) adds one hour during daylight saving time. For example, on the first day of DST this year:

  $date = date_make_date('2008-03-09T10:24:00', 'UTC', DATE_ISO);
  print_r ($date);

outputs one hour later: stdClass Object ( [value] => 2008-03-09 11:24:00 [timestamp] => 1205065440 [timezone] => UTC )

Doing the same thing for a date during standard time returns the same date as input:

  $date = date_make_date('2008-03-08T10:24:00', 'UTC', DATE_ISO);
  print_r ($date);

stdClass Object ( [value] => 2008-03-08 10:24:00 [timestamp] => 1204971840 [timezone] => UTC )

Just in case I'm misunderstanding the date_make_time API (a distinct possibility), here's a roundtrip example (similar to one in the Date API unit test) that I'm more confident should return the input date:

  $unix = date_convert('2008-03-09T10:24:00', DATE_DATETIME, DATE_UNIX);
  $datetime = date_convert($unix, DATE_UNIX, DATE_DATETIME);
  print_r ($unix); print '<br>'; print ($datetime);

1205061840
2008-03-09 12:24:00 

The Unix date looks correct to me (3600 seconds earlier than the 2008-03-09 11:24 printed above), but the datetime is 2 hours later than the input time.

The above examples were all created with the site set to UTC (and a fresh Drupal 5.7 install, PHP 4.4.7 on my local machine using MAMP). I also observed the same behavior on a old test site still on Drupal 5.2, PHP 4.4.8, and US/Pacific.

By "compatibility setting", do you mean whether the "Date PHP4" module is enabled? If so, yes, I have that enabled when using PHP 4.4.7 (using date_convert under PHP 4 without the Date PHP4 module gives a WSOD, not surprisingly). When testing on PHP 5.2, I see no problems whether or not Date PHP4 is enabled (maybe the PHP4 compatibility layer isn't used at all under PHP 5.2?).

My simple test: paste my date_convert snippet in #2 on a new page with PHP input format, then hit Preview.

This fixes all of the date API and date field problems I've seen: dates during DST and outside DST both work correctly, either using Date API directly or using a date as a CCK field. Thanks!

But I did some testing with Calendar 5.x-2.x-dev (dated 23-April), and found a problem. Dates displayed on the calendar are displayed with some timezone offset subtracted in certain cases. When my site timezone is set to US/Pacific, a 10:00 event is displayed as 02:00 on the calendar. Changing the site timezone to US/Eastern changes the display to 06:00. Strangely, changing the site timezone to Etc/GMT-8 keeps the calendar event displayed correctly, at 10:00. (These are all for a CCK date field not using any timezone conversion.)

I'll have to test some more to see if this is a bad setting on my part somewhere. If not, I can open a new issue to make it easier to track. (All this happens with PHP 4; I've been unable to test against PHP 5.2 this morning for some reason).

Edit: I saw another issue somewhere about the calendar problem, saying the calendar module needed updating for changes in Date. So I'm not worrying about it.