1 files changed, 16 insertions, 9 deletions
diff --git a/activesupport/lib/active_support/core_ext/hash/keys.rb b/activesupport/lib/active_support/core_ext/hash/keys.rb
index d8748b1138..230a84dabc 100644
--- a/activesupport/lib/active_support/core_ext/hash/keys.rb
+++ b/activesupport/lib/active_support/core_ext/hash/keys.rb
@@ -1,7 +1,11 @@
 class Hash
   # Return a new hash with all keys converted to strings.
   def stringify_keys
-    dup.stringify_keys!
+    result = {}
+    keys.each do |key|
+      result[key.to_s] = self[key]
+    end
+    result
   end
 
   # Destructively convert all keys to strings.
@@ -15,19 +19,22 @@ class Hash
   # Return a new hash with all keys converted to symbols, as long as
   # they respond to +to_sym+.
   def symbolize_keys
-    dup.symbolize_keys!
+    result = {}
+    keys.each do |key|
+      result[(key.to_sym rescue key)] = self[key]
+    end
+    result
   end
+  alias_method :to_options,  :symbolize_keys
 
   # Destructively convert all keys to symbols, as long as they respond
   # to +to_sym+.
   def symbolize_keys!
     keys.each do |key|
-      self[(key.to_sym rescue key) || key] = delete(key)
+      self[(key.to_sym rescue key)] = delete(key)
     end
     self
   end
-
-  alias_method :to_options,  :symbolize_keys
   alias_method :to_options!, :symbolize_keys!
 
   # Validate all keys in a hash match *valid keys, raising ArgumentError on a mismatch.
@@ -35,13 +42,13 @@ class Hash
   # as keys, this will fail.
   #
   # ==== Examples
-  #   { :name => "Rob", :years => "28" }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key: years"
-  #   { :name => "Rob", :age => "28" }.assert_valid_keys("name", "age") # => raises "ArgumentError: Unknown key: name"
-  #   { :name => "Rob", :age => "28" }.assert_valid_keys(:name, :age) # => passes, raises nothing
+  #   { :name => 'Rob', :years => '28' }.assert_valid_keys(:name, :age) # => raises "ArgumentError: Unknown key: years"
+  #   { :name => 'Rob', :age => '28' }.assert_valid_keys('name', 'age') # => raises "ArgumentError: Unknown key: name"
+  #   { :name => 'Rob', :age => '28' }.assert_valid_keys(:name, :age) # => passes, raises nothing
   def assert_valid_keys(*valid_keys)
     valid_keys.flatten!
     each_key do |k|
-      raise(ArgumentError, "Unknown key: #{k}") unless valid_keys.include?(k)
+      raise ArgumentError.new("Unknown key: #{k}") unless valid_keys.include?(k)
     end
   end
 end