Protect body ivar from being clobbered by the mailer template assigns

actionmailer/lib/action_mailer/base.rb

@@ -296,6 +296,9 @@ class Base
     @@default_implicit_parts_order = [ "text/html", "text/enriched", "text/plain" ]
     cattr_accessor :default_implicit_parts_order
 
+    cattr_reader :protected_instance_variables
+    @@protected_instance_variables = %w(@body)
+
     # Specify the BCC addresses for the message
     adv_attr_accessor :bcc
 

actionmailer/test/fixtures/test_mailer/body_ivar.erb

+body: <%= @body %>
+bar: <%= @bar %>
\ No newline at end of file

actionmailer/test/mail_service_test.rb

@@ -273,6 +273,13 @@ def return_path
     headers      "return-path" => "another@somewhere.test"
   end
 
+  def body_ivar(recipient)
+    recipients   recipient
+    subject      "Body as a local variable"
+    from         "test@example.com"
+    body         :body => "foo", :bar => "baz"
+  end
+
   class <<self
     attr_accessor :received_body
   end
@@ -926,6 +933,11 @@ def test_return_path_with_deliver
     TestMailer.deliver_return_path
     assert_match %r{^Return-Path: <another@somewhere.test>}, MockSMTP.deliveries[0][0]
   end
+
+  def test_body_is_stored_as_an_ivar
+    mail = TestMailer.create_body_ivar(@recipient)
+    assert_equal "body: foo\nbar: baz", mail.body
+  end
 end
 
 end # uses_mocha

actionpack/lib/action_view/base.rb

@@ -296,9 +296,9 @@ def _evaluate_assigns_and_ivars #:nodoc:
           @assigns.each { |key, value| instance_variable_set("@#{key}", value) }
 
           if @controller
-            variables = @controller.instance_variables
+            variables = @controller.instance_variable_names
             variables -= @controller.protected_instance_variables if @controller.respond_to?(:protected_instance_variables)
-            variables.each {|name| instance_variable_set(name, @controller.instance_variable_get(name)) }
+            variables.each { |name| instance_variable_set(name, @controller.instance_variable_get(name)) }
           end
 
           @assigns_added = true