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Date: Fri, 30 Jan 2015 21:04:30 -0800
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Subject: Magic getter bug tickled by Moodle
From: rasmus@lerdorf.com (Rasmus Lerdorf)

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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_navi=
gation.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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