Duplicate column_defaults properly (closes #6115)

activerecord/lib/active_record/core.rb

@@ -1,5 +1,6 @@
 require 'active_support/concern'
 require 'active_support/core_ext/hash/indifferent_access'
+require 'active_support/core_ext/object/duplicable'
 require 'thread'
 
 module ActiveRecord
@@ -165,7 +166,9 @@ module ActiveRecord
     #   # Instantiates a single new object bypassing mass-assignment security
     #   User.new({ :first_name => 'Jamie', :is_admin => true }, :without_protection => true)
     def initialize(attributes = nil, options = {})
-      @attributes = self.class.initialize_attributes(self.class.column_defaults.dup)
+      # TODO: use deep_dup after fixing it to also dup values
+      defaults = Hash[self.class.column_defaults.map { |k, v| [k, v.duplicable? ? v.dup : v] }]
+      @attributes = self.class.initialize_attributes(defaults)
       @columns_hash = self.class.column_types.dup
 
       init_internals

activerecord/test/cases/base_test.rb

@@ -1909,7 +1909,7 @@ class BasicsTest < ActiveRecord::TestCase
   end
 
   def test_attribute_names
-    assert_equal ["id", "type", "ruby_type", "firm_id", "firm_name", "name", "client_of", "rating", "account_id"],
+    assert_equal ["id", "type", "ruby_type", "firm_id", "firm_name", "name", "client_of", "rating", "account_id", "description"],
                  Company.attribute_names
   end
 
@@ -2001,6 +2001,12 @@ class BasicsTest < ActiveRecord::TestCase
     assert_nil hash['firm_name']
   end
 
+  def test_default_values_are_deeply_dupped
+    company = Company.new
+    company.description << "foo"
+    assert_equal "", Company.new.description
+  end
+
   ["find_by", "find_by!"].each do |meth|
     test "#{meth} delegates to scoped" do
       record = stub

activerecord/test/schema/schema.rb

@@ -173,6 +173,7 @@ ActiveRecord::Schema.define do
     t.integer :client_of
     t.integer :rating, :default => 1
     t.integer :account_id
+    t.string :description, :null => false, :default => ""
   end
 
   add_index :companies, [:firm_id, :type, :rating, :ruby_type], :name => "company_index"