alias_method/module bug in ruby 1.8

Yet another bug I’ve found in ruby 1.8

class A
  def a
    :a
  end
end

module M
  def a
    super
  end
  alias_method :b, :a
end

class B < A
  include M
end

p B.new.a  => :a
p B.new.b  # in `b': super: no superclass method `a' (NoMethodError)

If you alias a method defined in a module (aliasing the method inside of the module) then calls to super inside that method will no longer work. The fix for this is to alias the method in the class you’ve included the module in, instead of in the module itself. For the lib I’m writing I have a case where this is not possible so that’s why this bug really sucks for me.

This error only occurs in ruby 1.8, it functions correctly in 1.9.

I’ve added a ticket to rubyforge tracker.