Re: Interesting interaction between debug hooks, the garbage collector, and "open" VM instructions

[Roberto Ierusalimschy <roberto@...>]

> In extremely convoluted situations, if a debug hook is called
> immediately before an open VM instruction, and then proceeds to do a
> garbage collection, then the behaviour of the program can change. This
> is shown in the example code below, which will print "fail" if the
> debug hook is set, and "pass" if it isn't:
> 
> [...]
> 
>   // Change a the {...} construct to use the un-used b through to f stack slots.
> [...]

Can you explain the problem? (I mean, why your example has that
behavior.)  May this problem happen with "original" Lua opcodes?

-- Roberto