Question regarding GC of udata across states

[Olivier Hamel <evilpineapple@...>]

Greetings,

Let's say I create a udata in the root state of a Lua instance. I then 
anchor it down by adding a reference to it in the registry of the root 
state. Later, it gets passed around to other coroutines and all 
references to it disappear in the root state except the one in the 
registry. It won't be collected by the root state, but what happens if 
all references to it disappear in the substate it was passed to? Could 
it be potentially collected by the substate, regardless that it's still 
in reference by the registry of the root state?

I haven't yet encountered such a problem, but I've only been able to 
conduct limited tests, and the Lua src is somewhat hard to follow when 
you're not used to where everything is.

Olivier Hamel