This should be handled by the default respond_to?, no?
check_convert_type uses vm_object_respond_to, which uses Kernel#respond_to?, so I am not sure what's going wrong here.

The issue seems to be there is no equivalent of rb_check_funcall at the Ruby level.

@eregon Could there be an issue with vm_object_respond_to ? The following example:

class Test
  def respond_to?(method_name, include_private = false)
    puts "IN RESPOND TO"
    true
  end
end
test = Test.new
puts "test.respond_to? :to_ary - #{test.respond_to? :to_ary}"
puts "Rubinius::Type.object_respond_to? test, :to_ary, true - #{Rubinius::Type.object_respond_to? test, :to_ary, true}"

Outputs:

IN RESPOND TO
test.respond_to? :to_ary - true
Rubinius::Type.object_respond_to? test, :to_ary, true - false

@bjfish Yes, vm_object_respond_to is bound to BasicObject#respond_to?, so indeed we should probably try calling respond_to? dynamically. I tried a few things but gave up for now since it seems there are many differences here with MRI and it's quite hard to follow the code.

This was fixed by #4146