升级php5.6提示，Codeigniter 2.x项目提示
A PHP Error was encountered
Severity: Notice
Message: Only variable references should be returned by reference
Filename: core/Common.php
Line Number: 257
解决方法
进入system/core,修改Comm.php 257行
修改前
return $_config[0] =& $config;
修改后
$_config[0] =& $config; return $_config[0];
