From 0c659e26cb8839dec8eb2559a8c7ff98a56c4e88 Mon Sep 17 00:00:00 2001
From: shugo <shugo@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Thu, 17 Dec 2015 22:43:35 +0000
Subject: [PATCH] * vm.c (rb_vm_check_redefinition_opt_method): should check
 the real   class instead of the origin iclass.   [ruby-core:72188] [Bug
 #11826]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53173 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog                |  6 ++++++
 test/ruby/test_module.rb | 16 ++++++++++++++++
 vm.c                     |  3 +++
 3 files changed, 25 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 0736c872e3..f87a71a43f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Dec 18 07:39:01 2015  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* vm.c (rb_vm_check_redefinition_opt_method): should check the real
+	  class instead of the origin iclass.
+	  [ruby-core:72188] [Bug #11826]
+
 Thu Dec 17 22:13:10 2015  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* vm_args.c (vm_caller_setup_arg_block): remove code for ifunc
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 5356983135..1a852f84a0 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -1695,6 +1695,22 @@ class TestModule < Test::Unit::TestCase
     assert_equal(0, 1 / 2)
   end
 
+  def test_redefine_optmethod_after_prepend
+    bug11826 = '[ruby-core:72188] [Bug #11826]'
+    assert_separately [], %{
+      module M
+      end
+      class Fixnum
+        prepend M
+        def /(other)
+          quo(other)
+        end
+      end
+      assert_equal(1 / 2r, 1 / 2, "#{bug11826}")
+    }, ignore_stderr: true
+    assert_equal(0, 1 / 2)
+  end
+
   def test_prepend_visibility
     bug8005 = '[ruby-core:53106] [Bug #8005]'
     c = Class.new do
diff --git a/vm.c b/vm.c
index 3c80cd16aa..2dd2dfc879 100644
--- a/vm.c
+++ b/vm.c
@@ -1400,6 +1400,9 @@ static void
 rb_vm_check_redefinition_opt_method(const rb_method_entry_t *me, VALUE klass)
 {
     st_data_t bop;
+    if (RB_TYPE_P(klass, T_ICLASS) && FL_TEST(klass, RICLASS_IS_ORIGIN)) {
+       klass = RBASIC_CLASS(klass);
+    }
     if (me->def->type == VM_METHOD_TYPE_CFUNC) {
 	if (st_lookup(vm_opt_method_table, (st_data_t)me, &bop)) {
 	    int flag = vm_redefinition_check_flag(klass);