Magic getter bug tickled by Moodle

There is something weird going on with PHP7 and the moodle_page class and all its magic methods. It dies with a: /var/www/moodle/blocks/navigation/block_navigation.php(223) : Notice - Undefined property: moodle_page::$navigation /var/www/moodle/blocks/navigation/block_navigation.php(223) : Fatal error - __clone method called on non-object That code is: 222 $this->page->navigation->initialise(); 223 return clone($this->page->navigation); See: https://github.com/moodle/moodle/blob/master/blocks/navigation/block_navigation.php#L222-L223 $this->page_navigation is created on that initial call through the wonders of this magic: https://github.com/moodle/moodle/blob/master/lib/pagelib.php#L757-L772 Which somehow leads us to read 8 bytes in a free'ed block: https://gist.github.com/anonymous/f9d1f53b1205d29d86cc but I am not having much luck dwindling it down to a simpler reproduce case. If you know this code or have a couple of hours to spare, could you see if you could reduce it to something more manageable for us? (and yes, same code is fine in 5.6) -Rasmus

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