[Kc] subtle distinction that looks like a bug

[Jason Rush]

> The massive headaches that would ensue if my initial approach did what
> I wanted are easy to imagine. Or are they? When an array variable
> holds copies instead of aliases, as they usually do, there would be
> difference.

Isn't it due to Q being pass-by-reference that allows you to assign
$_[0] and have the value assigned to $a because it is the same memory
location?

If it was pass-by-copy and not pass-by-reference, the values from $a,
$b, and $c would be passed in and Q would not have access to the
memory locations for $a, $b, and $c and thus would not be able to
store values there.