I recently changed my server from CentOS 6 to CentOS 7 and in the process decided that to avoid having to upgrade everything later, installing PHP 7.2 before migrating the sites would be a better option than staying with the default PHP 5.4.

This was a good idea – mostly. It forced me to upgrade a couple of mediawiki installs that hadn’t been touched in a while and those were migrated ok. When it came to migrating the Shartak Forum I was starting to think I should have gone for a slightly older version of PHP because SMF 1.1 (Simple Machines Forum) doesn’t work on such a recent version of PHP. It wasn’t just a minor issue, functions such as mysql_* that had been removed in PHP 7 were all over the place!

Time to take the plunge and upgrade to SMF 2.0 which had been stable for several years but there had never been a reason to upgrade before now. Looking at the large amount of spam user accounts and the upgrade process documentation, I decided it would be easier to start from scratch instead of trying to upgrade SMF 1.1 (with some custom tweaks) to 2.0.

I installed the SMF 2.0 code, configured the theme, found that only one of the old tweaks was really still needed and put it live. Then I checked the error logs in the SMF admin panel and found there were thousands of errors after just a few hours of it being live!

Function create_function() is deprecated

It turned out that SMF 2.0.15 only supports up to PHP 7.1 as PHP 7.2 is deprecating create_function() and this is used by the BBCode parser.

After some searching, I came across a message on the SMF forum that suggested adding an exception to the error handler to prevent it logging the deprecation warnings. The suggestion of comparing the version using the builtin PHP method version_compare() was taken into account and here is my version of the solution.

--- Sources/Errors.orig.php 2018-05-23 14:21:57.933367060 +0100
+++ Sources/Errors.php 2018-05-23 13:47:45.711567251 +0100
@@ -203,6 +203,10 @@
 {
 global $settings, $modSettings, $db_show_debug;

+ // Disable PHP 7.2 "Function create_function() is deprecated" errors from filling the forum error logs
+ if (defined('E_DEPRECATED') && $error_level == E_DEPRECATED && (version_compare(phpversion(), '7.2') >= 0) && strpos($error_string, 'Function create_function() is deprecated') !== false)
+ return;
+
 // Ignore errors if we're ignoring them or they are strict notices from PHP 5 (which cannot be solved without breaking PHP 4.)
 if (error_reporting() == 0 || (defined('E_STRICT') && $error_level == E_STRICT && (empty($modSettings['enableErrorLogging']) || $modSettings['enableErrorLogging'] != 2)))
 return;

It’s not a perfect fix but it’ll do until SMF 2.1 is released. I hope this helps someone else searching for the same issue.