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Date: Thu, 16 Jun 2011 16:51:09 -0700
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Subject: date_diff broken?
From: smalyshev@sugarcrm.com (Stas Malyshev)

Hi!

I've been looking into various tests and discovered something strange in 
date_diff. Example code:

<?php
$start = new DateTime('2010-10-04 02:18:48 EDT');
$end   = new DateTime('2010-11-06 18:38:28 EDT');
$int = $start->diff($end);
var_dump($start);

As a result of this I'm getting this:

object(DateTime)#1 (3) {
   ["date"]=>
   string(19) "2010-10-04 06:18:48"
   ["timezone_type"]=>
   int(2)
   ["timezone"]=>
   string(3) "EDT"
}

As you can see, the date in $start changed, even though it shouldn't 
happen. Looks like it's because of timelib_diff() which has this:

     timelib_apply_localtime(one, 0);
     timelib_apply_localtime(two, 0);

which converts times in diff arguments to localtime. It then does:

     timelib_apply_localtime(one, 1);
     timelib_apply_localtime(two, 1);

which is supposed to convert them back, but in fact it does not, since 
first conversion seems to have killed TZ information. I'd propose to fix 
it by making time_diff operate on copies of one and two instead of real 
structures, but maybe somebody has a better idea?
-- 
Stanislav Malyshev, Software Architect
SugarCRM: http://www.sugarcrm.com/
(408)454-6900 ext. 227