[STDERR] PHP Strict Standards: Only variables should be passed by reference

[postcd]

Hello, in vB 4.2.5 on PHP 5.6 i am seeing 3 errors for which i am quoting relevant code and highlighting in bold text the line that is linked in error message.
The first two seems to appear at same time when making reply.

[STDERR] PHP Strict Standards: Only variables should be passed by reference in newreply.php

if ($vbulletin->GPC_exists['emailupdate'])
{
$newpost['emailupdate'] = $vbulletin->GPC['emailupdate'];
}
else
{
$newpost['emailupdate'] = array_pop($array = array_keys(fetch_emailchecked($threadinfo, $vbulletin->userinfo)));
}

[STDERR] PHP Strict Standards: Only variables should be assigned by reference in includes/class_dm_threadpost.php(764) : eval()'d code

<?php
if (!class_exists('vB_DataManager', false))

[STDERR] PHP Strict Standards: Only variables should be assigned by reference in register.php

// check for multireg
if ($vbulletin->userinfo['userid'] AND !$vbulletin->options['allowmultiregs'])
{
eval(standard_error(fetch_error('alreadyregistered ', $vbulletin->userinfo['username'], $vbulletin->session->vars['sessionurl'])));
}

// init user datamanager class
$userdata =& datamanager_init('User', $vbulletin, ERRTYPE_ARRAY);

// coppa option

Can You please suggest modification so the error is prevented?