--TEST--

Deprecate using null as key in array_key_exists()

--FILE--

$arr = ['foo' => 'bar', '' => 'baz'];

var_dump(array_key_exists(null, $arr));

var_dump(array_key_exists('', $arr));

--EXPECTF--

Deprecated: Using null as the key parameter for array_key_exists() is deprecated, use an empty string instead in %s on line %d

bool(true)

bool(true)