Check compatibility with PHP 7.2

[asgrim]

Currently .travis.yml doesn't check PHP nightly (or even 7.1 for that matter) so we should add that in.

Related, and may be of relevance to this: https://twitter.com/WyriHaximus/status/796016769525809152

Thanks for hat tip to @WyriHaximus

[WyriHaximus]

No problem @asgrim, I'll try to uncover more details and keep you posted. Also you might want to put nightly on allowed to fail for now as it's codebase is volatile.

[Ocramius]

Note: 7.2 cannot really be tested in depth without Zend\Code supporting it (yet)

[WyriHaximus]

Think I just ruled out an issue with ReflectionClass::getDocComment, will continue digging to see why the code behaves in unexpected ways: https://twitter.com/WyriHaximus/status/796094099858321409

[WyriHaximus]

The issue has been uncovered, calling get_class with null as argument is deprecated in 7.2, https://twitter.com/kelunik/status/796098864419835904, and thus raises an error. As demonstrated at https://travis-ci.org/WyriHaximus/php-7.2-tests/jobs/174334333#L177 with https://github.com/WyriHaximus/php-7.2-tests/blob/master/test.php Origin RFC: https://wiki.php.net/rfc/get_class_disallow_null_parameter

Sorry for jumping the gun a wee bit 😊

[asgrim]

Ah yes, that makes sense. Thanks for reporting back @WyriHaximus :)

[WyriHaximus]

No problem @asgrim, it is the least I can do :)

[kukulich]

This could be closed probably.

[Ocramius]

Can indeed be closed: handled in #316