Hi internals! We have recently been reviewing the interaction between ReflectionFunctionAbstract::getClosure(), a mechanism which converts an ordinary function or method into a "fake" closure, and closure rebinding using Closure::bindTo() and Closure::call().
It turns out that this combination has not yet received testing and multiple crashes and leaks were found and fixed [1] [2] [3] [4]. We have one last outstanding changeset [5] waiting to land, which we want to check back with internals first, as it constitutes a BC break late in the PHP 7.0 release cycle. This changeset forbids rebinding the *scope* of closures returned by getClosure() completely. The background of this change is that PHP 7 includes optimizations that early-bind the scope of self:: during compilation (and there are more optimizations of this nature pending to land in PHP 7.1). This means that attempts to change the meaning of "self" in an ordinary method at runtime will not always succeed and lead to inconsistent results. Based on feedback received on an earlier version of this patch [6] [7], we have not added any additional restrictions on rebinding of $this. getClosure()s of userland methods can still be bound to arbitrary $this values and getClosure()s of internal methods can still be bound to "compatible" $this values. (If someone sees a problem with allowing the former, please speak up!) Note that all this applies to ReflectionFunctionAbstract::getClosure() only. Rebinding behavior of ordinary closures doesn't change. It would be appreciated if some more people familiar with the closure implementation could take a look at our rebinding rules and see if there's any situations that aren't covered yet and could be problematic. Thanks, Nikita [1] https://bugs.php.net/bug.php?id=70630 [2] https://bugs.php.net/bug.php?id=70674 [3] https://bugs.php.net/bug.php?id=70681 [4] https://bugs.php.net/bug.php?id=70685 [5] https://github.com/php/php-src/pull/1560 [6] https://github.com/php/php-src/commit/517b5536259ecf7697f353f4bfbafde857fc1f81 [7] https://github.com/php/php-src/commit/881c50252066132f83e190325e344f532be19033
