Forum: Ruby ObjectSpace._id2ref is giving different type output on Ruby 1.9.3p392 and Ruby 2.0.0p0 ?

Couldn't understand - Why does `ObjectSpace._id2ref` giving different
type of output on `Ruby 1.9.3p392` and `Ruby 2.0p0` ?

***Ruby 1.9.3p392***

    C:\>ruby -v
    ruby 1.9.3p392 (2013-02-22) [i386-mingw32]
    C:\>irb --simple-prompt
    >> class Foo ; end
    #=> nil
    >> Foo.object_id
    #=> 17569464
    >> ObjectSpace._id2ref(17569464)
    #=> Foo
    >> Foo.new.singleton_class
    #=> #<Class:#<Foo:0x2041830>>
    >> Foo.new.singleton_class.object_id
    #=> 17075124
    >> ObjectSpace._id2ref(17075124)
    #=> "\x00"

***Ruby 2.0.0p0***

    C:\>ruby -v
    ruby 2.0.0p0 (2013-02-24) [i386-mingw32]
    C:\>irb --simple-prompt
    DL is deprecated, please use Fiddle
    >> class Foo ; end
    #=> nil
    >> Foo.object_id
    #=> 17197176
    >> ObjectSpace._id2ref(17197176)
    #=> Foo
    >> Foo.new.singleton_class.object_id
    #=> 19181436
    >> ObjectSpace._id2ref(19181436)
    #RangeError: 0x124af7c is recycled object
    #        from (irb):5:in `_id2ref'
    #        from (irb):5
    #        from C:/Ruby200/bin/irb:12:in `<main>'
    >> Foo.new.singleton_class.object_id
    #=> 17454324
    >> ObjectSpace._id2ref(17454324)
    #RangeError: 0x10a54f4 is not id value
    #       from (irb):7:in `_id2ref'
    #       from (irb):7
    #       from C:/Ruby200/bin/irb:12:in `<main>'
    >> Foo.new.singleton_class.object_id
    #=> 17139816
    >> ObjectSpace._id2ref(17139816)
    #=> "c"

already fixed in ruby-trunk


and before you ask, yeah the object_id of nil is changed in ruby-trunk 
too