Description:
------------
Regex: https://regex101.com/r/aZ7pL6/1 which matches the subject.

However, on PHP7 (and HHVM...), the regular expression fails to match anything.

If I change the first character matching from '[3-5789]' to '[3-578]', it starts working on PHP7.

Demo @ https://3v4l.org/0SMiZ

Test script:
---------------
<?php

$subject = '512345678';

$failingPattern = '/^(?:[3-5789]\d{8})$/x';

$result = preg_match($failingPattern , $subject, $groups, PREG_OFFSET_CAPTURE);

var_dump($result, $groups);

Expected result:
----------------
int(1)
array(1) {
  [0]=>
  array(2) {
    [0]=>
    string(9) "512345678"
    [1]=>
    int(0)
  }
}


Actual result:
--------------
int(0)
array(0) {
}