Array#slice! broken on Rubinius

[toroidal-code]

Expected behavior:

Array#slice! returns a fully-functional Array (intuitively a Concurrent::Array) containing the data removed from the primary array.

Actual behavior:

Array#slice! returns a near-complete version of Array, but with no valid @_monitor, thus causing any methods that require synchronization on the object to fail.

Example:

~ ❯❯❯ uname -a
Linux 4.6.4-1-ARCH #1 SMP PREEMPT Mon Jul 11 19:12:32 CEST 2016 x86_64 GNU/Linux
~ ❯❯❯ ruby --version
rubinius 3.47 (2.3.1 43e411b2 2016-07-15 3.8.0) [x86_64-linux-gnu]
~ ❯❯❯ pry
[1] pry(main)> require 'concurrent/array'
=> true
[2] pry(main)> a = Concurrent::Array.new [1,2,3,4,5,6]
=> [1, 2, 3, 4, 5, 6]
[3] pry(main)> a.instance_variable_get :@_monitor
=> #<Monitor:0x98b30 @mon_count=0, @mon_mutex=#<Mutex:0x98c28 @owner=nil>, @mon_owner=nil>
[4] pry(main)> b = a.slice!(0..2)
=> #<Concurrent::Array:0x4c7d4>
[5] pry(main)> puts b
NoMethodError: undefined method `synchronize' on nil:NilClass.
from core/zed.rb:1425:in `synchronize (method_missing)'
[6] pry(main)> b.instance_variable_get :@_monitor
=> nil

---

I honestly have no idea what's going on with this. I tested a few other things, and it looks like #slice! and indexing with a range (e.g. a[0..2]) both return invalid Concurrent::Arrays. My first thought from looking in thread_safe/util/array_hash_rbx.rb is that _mon_initialize isn't being called when it should be, but I don't know.

[jdantonio]

Thank you very much for bringing this to our attention. We'll take a look at it ASAP.

[pitr-ch]

@thedarkone Would you have time to look at this issue?