Description:
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Testing public properties on DateInterval objects with isset returns false even when they contain data. Running a print_r or var_dump on the object BEFORE testing isset will provide the desired result.

Test script:
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$currentDate = new DateTime();
$targetDate = new DateTime('2015-03-05 11:11:11');
$interval = $currentDate->diff($targetDate);
// var_dump($interval); // Uncomment and isset will give the expected response
var_dump($interval->y);
var_dump($interval->m);
var_dump(isset($interval->y));
var_dump(isset($interval->m));


Expected result:
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int(0)
int(2)
bool(true)
bool(true)


Actual result:
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int(0)
int(2)
bool(false)
bool(false)