Bug #72243 [Com]: DateTimes fail to compare correctly when a DateTimeZone is set

Edit report at https://bugs.php.net/bug.php?id=72243&edit=1

 ID:                 72243
 Comment by:         php-bugs at allenjb dot me dot uk
 Reported by:        Rican7 at gmail dot com
 Summary:            DateTimes fail to compare correctly when a
                     DateTimeZone is set
 Status:             Open
 Type:               Bug
 Package:            Date/time related
 PHP Version:        7.0.6
 Block user comment: N
 Private report:     N

 New Comment:

Refreshing the broken 3v4l (https://3v4l.org/WkjAA ) for current versions shows this issues appears to be fixed as of 7.0.17 and 7.1.3


Previous Comments:
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[2016-05-19 18:16:35] Rican7 at gmail dot com

May be related to bug #68474

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[2016-05-19 18:15:37] Rican7 at gmail dot com

These 3v4l scripts show the bug in action:

- Broken (TZ abbreviation): https://3v4l.org/WkjAA
- Working (IANA TZ): https://3v4l.org/MDqHr

------------------------------------------------------------------------
[2016-05-19 18:13:59] Rican7 at gmail dot com

Description:
------------
DateTime instances are supposed to be natively "comparable" (using `==`, `>`, `<`, etc).

Unfortunately, a colleague and I just noticed that if a Time Zone is updated on a compared instance, than the comparison fails... but only if the time zone isn't an IANA identifier. Really strange. What's worse, is that it seems to "magically" start to work again if a (seemingly idempotent) `getTimestamp()` call is made on the instance that had the new time-zone applied. Is this due to a lazy calculation of the internal timestamp that isn't getting validated when a new time zone is applied?

Test script:
---------------
<?php

$datetime = new DateTime(null, new DateTimeZone('UTC'));
$datetime_2 = clone $datetime;
$datetime_2->add(new DateInterval('PT2S'));

var_dump($datetime < $datetime_2);
var_dump($datetime->getTimestamp() < $datetime_2->getTimestamp());

$datetime_2->setTimezone(new DateTimeZone('EST'));

var_dump($datetime < $datetime_2);
var_dump($datetime->getTimestamp() < $datetime_2->getTimestamp());

// Now that `getTimestamp()` has been called, it'll "magically" work...
var_dump($datetime < $datetime_2);

Expected result:
----------------
bool(true)
bool(true)
bool(true)
bool(true)
bool(true)

Actual result:
--------------
bool(true)
bool(true)
bool(false)
bool(true)
bool(true)


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Edit this bug report at https://bugs.php.net/bug.php?id=72243&edit=1