[Ruby] Private constants check

private_constants.rb

require 'active_support'

module MyConcern
  extend ActiveSupport::Concern

  class PrivateClass
    def self.pcall
      :pcall_result
    end
  end
  private_constant :PrivateClass
  
  def some_call
    PrivateClass.pcall
  end
end

class MyClass
  include MyConcern
end

MyClass.new.some_call
#=> :pcall_result

MyClass::PrivateClass
#=> NameError: private constant #<MyConcern:0x007fd6e3d5cbd8>::PrivateClass referenced