Here is my minimal example: <https://play.nim-lang.org/#ix=4g1k>
(This does not actually run in the playground because it needs devel)
This example creates two threads, a ref object is created in one thread and
sent to the other over a channel. (For now, ignore the fact there is no locking
or memory barrier in place protecting the object itself).
This example works fine. The output looks like this:
send a thing, @t=140031723291264 @t.val=140031728230496 t=42
recv a thing, @t=140031725388432 @t.val=140031728230496 t=42
Run
This shows that the ref object itself is copied by the channel, as the sender
and receiver have their `t` on a different address. The object the ref points
to is properly moved though, as it has the same address (`@t.val)`
This works because the created object `t` in `txProc()` has only one reference,
so `channel.send()` will properly move the object because RC == 1 and `send`
explicitly sinks its argument.
Uncommenting line 13 will cause problems though: there will be more then one
reference to the same object, so after the `send()`, both threads will have a
reference to the same object. Because the RC itself is not locked or atomic,
this will cause UB or worse.
