Description:
------------
php5.3.8 usually report：Fatal error: Call to undefined function
but xxx function exists.

Test script:
---------------
function is_ascii($string) {
	return preg_match('%^(?:
	[\x09\x0A\x0D\x20-\x7E]             # ASCII
	|[\xC2-\xDF][\x80-\xBF]             # non-overlong 2-byte
	)*$%xs', $string);
}

$str = "123asd！";

if(is_ascii($str)) {
	echo "ansi";
} else {
	echo "Not ansi";
}