PHPExcel_Shared_Date::PHPToExcel does not work with objects implementing DateTimeInterface

[cvoysey]

When attempting to use PHPExcel_Shared_Date::PHPToExcel with a DateTimeImmutable false is being returned rather than the converted value.

<?php
$date = new DateTime();
$excel_date = PHPExcel_Shared_Date::PHPToExcel($date);
var_dump($excel_date);

$date = new DateTimeImmutable();
$excel_date = PHPExcel_Shared_Date::PHPToExcel($date);
var_dump($excel_date);
?>

The above code will output:

double(42517.61150463)
bool(false)

It appears that the method uses instanceof DateTime rather than instanceof DateTimeInterface.

[PowerKiKi]

This has been done in PHPOffice/PhpSpreadsheet@850594c#diff-495ca961ee5a4a2ab5ae21e6a550a384L229 and more generally in DateTimeInterface are introduced in the context of PHPOffice/PhpSpreadsheet#7