replace serialize() with print_r() in stats() function in wp-includes/cache.php

[bobbingwide]

In PHP 5.3 it is no longer possible to serialize data that contains a SimpleXMLElement object. It produces a fatal error. See ​https://bugs.php.net/bug.php?id=49800

The stats() function attempts to determine the allocated space for objects in the cache by using strlen() of the serialized object.

This can fail for the reason above.

Given that the figure returned is simply an estimation of the space
I propose that the code is changed to use
print_r( $cache, true ) instead of serialize( $cache )

ie. to become
echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( print_r( $cache, true ) ) / 1024, 2 ) . 'k )</li>';

This TRAC was raised after a longish chain of events starting with #18488 and the final response (today) which led to another chance discovery of a similar problem in the debug-bar plugin.

​http://wordpress.org/support/topic/plugin-debug-bar-fatal-error-uncaught-exception-serialization-of-simplexmlelement-is-not-allowed

Replace serialize() with print_r() to avoid Fatal error (WP 3.5)

The way this estimation is presented is very misleading; it makes you think you're viewing the size of the cache in memory, rather than the lenght of it's serialization.

Other than that, switching to print_r() seems sane.