3 files changed, 38 insertions, 1 deletions
diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index bd70d2cde4..6818f32f55 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Fix issue with #class_inheritable_accessor saving updates to the parent class when initialized with an Array or Hash [mojombo]
+
 * Hash#to_xml supports Bignum and BigDecimal.  #6313 [edibiase]
 
 * Don't undefine #class in OptionMerger [Rick]
diff --git a/activesupport/lib/active_support/core_ext/class/inheritable_attributes.rb b/activesupport/lib/active_support/core_ext/class/inheritable_attributes.rb
index 2e70a64436..bc8bf09ab2 100644
--- a/activesupport/lib/active_support/core_ext/class/inheritable_attributes.rb
+++ b/activesupport/lib/active_support/core_ext/class/inheritable_attributes.rb
@@ -107,7 +107,12 @@ class Class # :nodoc:
   private 
     def inherited_with_inheritable_attributes(child)
       inherited_without_inheritable_attributes(child) if respond_to?(:inherited_without_inheritable_attributes)
-      child.instance_variable_set('@inheritable_attributes', inheritable_attributes.dup)
+      
+      new_inheritable_attributes = inheritable_attributes.inject({}) do |memo, (key, value)|
+        memo.update(key => (value.dup rescue value))
+      end
+      
+      child.instance_variable_set('@inheritable_attributes', new_inheritable_attributes)
     end
 
     alias inherited_without_inheritable_attributes inherited
diff --git a/activesupport/test/class_inheritable_attributes_test.rb b/activesupport/test/class_inheritable_attributes_test.rb
index 54e533e964..048b86135c 100644
--- a/activesupport/test/class_inheritable_attributes_test.rb
+++ b/activesupport/test/class_inheritable_attributes_test.rb
@@ -137,4 +137,34 @@ class ClassInheritableAttributesTest < Test::Unit::TestCase
     assert_equal 'b', @klass.b
     assert_equal 'B', @sub.b
   end
+  
+  def test_array_inheritance
+    @klass.class_inheritable_accessor :a
+    @klass.a = []
+
+    @sub = eval("class SubbyArray < @klass; end; SubbyArray")
+    
+    assert_equal [], @klass.a
+    assert_equal [], @sub.a
+    
+    @sub.a << :first
+    
+    assert_equal [:first], @sub.a
+    assert_equal [], @klass.a
+  end
+  
+  def test_array_inheritance
+    @klass.class_inheritable_accessor :a
+    @klass.a = {}
+
+    @sub = eval("class SubbyHash < @klass; end; SubbyHash")
+    
+    assert_equal Hash.new, @klass.a
+    assert_equal Hash.new, @sub.a
+    
+    @sub.a[:first] = :first
+    
+    assert_equal 1, @sub.a.keys.size
+    assert_equal 0, @klass.a.keys.size
+  end
 end