vm_method.c: check if frozen [Fix GH-1096]

* vm_method.c (set_method_visibility): should fail if the receiver
  is frozen.  [ruby-core:71489] [Bug #11687]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52579 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Sun Nov 15 18:28:43 2015  Kenichi Kamiya  <kachick1@gmail.com>
+
+	* vm_method.c (set_method_visibility): should fail if the receiver
+	  is frozen.  [ruby-core:71489] [Bug #11687]
+
 Sat Nov 14 22:15:07 2015  Tanaka Akira  <akr@fsij.org>
 
 	* ext/socket/lib/socket.rb: Specify frozen_string_literal: true.

test/ruby/test_module.rb

@@ -624,13 +624,22 @@ class TestModule < Test::Unit::TestCase
   end
 
   def test_freeze
-    m = Module.new
+    m = Module.new do
+      def self.baz; end
+      def bar; end
+    end
     m.freeze
     assert_raise(RuntimeError) do
       m.module_eval do
         def foo; end
       end
     end
+    assert_raise(RuntimeError) do
+      m.__send__ :private, :bar
+    end
+    assert_raise(RuntimeError) do
+      m.private_class_method :baz
+    end
   end
 
   def test_attr_obsoleted_flag

vm_method.c

@@ -1552,6 +1552,7 @@ set_method_visibility(VALUE self, int argc, const VALUE *argv, rb_method_visibil
 {
     int i;
 
+    rb_check_frozen(self);
     if (argc == 0) {
 	rb_warning("%"PRIsVALUE" with no argument is just ignored",
 		   QUOTE_ID(rb_frame_callee()));