Will getTimezone() EVER return false when invoked on a PHP DateTime or DateTimeImmutable object?

Question

In the docs it says that the function returns a DateTimeZone object on success or false on failure. My question is, in which cases will this result in a failure?

In my experience, it is never failing and it always returns a DateTimeZone object.

Answer 1

It can return false prior to PHP v8, when the typehint was added for the DateTimeInterface $object parameter:

var_dump(date_timezone_get(0));

In PHP >= 8.0:

Fatal error: Uncaught TypeError: date_timezone_get():
  Argument #1 ($object) must be of type DateTimeInterface, int given

In PHP < 8.0:

bool(false)