Description:
------------
filter_var rejects IPv6 scoped literal addresses. Scoped literal addresses are described at https://en.wikipedia.org/wiki/IPv6_address#Scoped_literal_IPv6_addresses_(with_zone_index)



[RFC 4007](https://tools.ietf.org/html/rfc4007):

a common notation to specify the scope zone, an implementation SHOULD
support the following format:
            <address>%<zone_id>
 where
      <address> is a literal IPv6 address,
      <zone_id> is a string identifying the zone of the address, and
      `%' is a delimiter character to distinguish between <address> and
      <zone_id>.

Test script:
---------------
https://3v4l.org/Lqnm0

<?php

$ip = "fe80::3549:8417:2ad0:ef6a%4";
var_dump(filter_var($ip, FILTER_VALIDATE_IP));

Expected result:
----------------
return true

Actual result:
--------------
return false