> I'm not sure though if it should be done by adding > 'foo::bar' to $a() or removing it from call_user_func().
call_user_func('foo::bar') work since 5.2.2 (see http://3v4l.org/k2SOU).
Is there a serious reason to break code that is perfectly fine since 2007.
Breaking BC needs a serious reason IMHO.
