Restore HWIA#stringify_keys! and update changelog

activerecord/lib/active_record/base.rb

@@ -1844,8 +1844,7 @@ module ActiveRecord #:nodoc:
       #   user.is_admin?  # => true
       def attributes=(new_attributes, guard_protected_attributes = true)
         return if new_attributes.nil?
-        attributes = new_attributes.dup
-        attributes.stringify_keys!
+        attributes = new_attributes.stringify_keys
 
         multi_parameter_attributes = []
         attributes = remove_attributes_protected_from_mass_assignment(attributes) if guard_protected_attributes

activesupport/CHANGELOG

@@ -1,5 +1,7 @@
 *Rails 3.0.0 [beta 3] (April 13th, 2010)*
 
+* HashWithIndifferentAccess: remove inherited symbolize_keys! since its keys are always strings.  [Santiago Pastorino]
+
 * Improve transliteration quality.  #4374 [Norman Clarke]
 
 * Speed up and add Ruby 1.9 support for ActiveSupport::Multibyte::Chars#tidy_bytes.  #4350 [Norman Clarke]

activesupport/lib/active_support/hash_with_indifferent_access.rb

@@ -111,8 +111,8 @@ module ActiveSupport
       super(convert_key(key))
     end
 
-    undef :stringify_keys!
-    def stringify_keys; to_hash.stringify_keys end
+    def stringify_keys!; self end
+    def stringify_keys; to_hash end
     undef :symbolize_keys!
     def symbolize_keys; to_hash.symbolize_keys end
     def to_options!; self end

activesupport/test/core_ext/hash_ext_test.rb

@@ -89,9 +89,9 @@ class HashExtTest < Test::Unit::TestCase
   end
 
   def test_stringify_keys_bang_for_hash_with_indifferent_access
-    assert_raise(NoMethodError) { @symbols.with_indifferent_access.dup.stringify_keys! }
-    assert_raise(NoMethodError) { @strings.with_indifferent_access.dup.stringify_keys! }
-    assert_raise(NoMethodError) { @mixed.with_indifferent_access.dup.stringify_keys! }
+    assert_equal @strings, @symbols.with_indifferent_access.dup.stringify_keys!
+    assert_equal @strings, @strings.with_indifferent_access.dup.stringify_keys!
+    assert_equal @strings, @mixed.with_indifferent_access.dup.stringify_keys!
   end
 
   def test_indifferent_assorted