Simple script to reproduce segfaults with Active Record in ruby-1.9.3p362. This style of scope is used by the kaminari gem to define its page scope - using a class method to define default_scope doesn't segfault.

ruby-1.9.3p362-segfault.rb

require 'active_record'

ActiveRecord::Base.establish_connection(:adapter => "sqlite3", :database => ":memory:")

ActiveRecord::Schema.define(:version => 1) do
  create_table :posts do |t|
    t.string :title
    t.timestamps
  end
end

class Post < ActiveRecord::Base
  default_scope { where(:published => true) }
  scope :page, Proc.new { |num| limit(10).offset(10 * (num - 1)) } do
    def current_page
      return 1 if limit_value.nil?
      (offset_value / limit_value) + 1
    end
  end
end

30.times do |i|
  Post.create! do |p|
    p.title = "Post #{i}"
  end
end

# Segfaults
Post.page(1)