cannot pass {:class_name => symbol} in belongs_to in AR 2.3.8 with Ruby 1.9.2

With Ruby 1.9.2 and ActiveRecord 2.3.8, I get a "TypeError: can't convert Symbol into String" when trying to resolve a belongs_to association, whose :class_name was passed a symbol:

class Publication < ActiveRecord::Base
  belongs_to :owner, :class_name => :User, :foreign_key => :user_id
end

If I change the :User symbol to a string, there is no error:

class Publication < ActiveRecord::Base
  belongs_to :owner, :class_name => "User", :foreign_key => :user_id
end

The error occurs at lib/active_record/base.rb:2232 because a symbol is passed to eval() instead of a String. This used to work just fine in Ruby 1.9.1 (by accident!) because of a bug http://redmine.ruby-lang.org/issues/show/2699 that is now fixed in Ruby 1.9.2.

My suggestion to fix the problem: make sure you run #to_s on the code being passed to eval(). IMHO this is generally a good thing to do, everywhere in Rails!

Thanks for your consideration.