[Wikitech-l] "must be of type int, int given"

I'm running into a weird problem, which made me reset my whole vagrant.

I assume this is not strictly a MediaWiki issue, but probably an HHVM problem, but maybe someone can help me here.

So, if I start a fresh MediaWiki Vagrant installation, and the vagrant ssh into the virtual machine, the fastest way to reproduce the issue is to start hhvmsh and type

function f():int { return 1; };

=f()

I get:

Hit fatal : Value returned from function f() must be of type int, int given

#0 at [:1]

#1 f(), called at [:1]

#2 include(), called at [:1]

Any way to circumvent this (besides getting rid of the type hint, obviously)? Update to a new HHVM version (According to Special:Version, the HHMV version is 3.12.14 (srv)?