4 files changed, 26 insertions, 2 deletions
diff --git a/ChangeLog b/ChangeLog
index f493fe332e..7b0d3a60e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+Thu Sep 26 16:51:00 2013  Shota Fukumori  <her@sorah.jp>
+
+	* insns.def (opt_regexpmatch2): Check String#=~ hasn't overridden
+	  before calling rb_reg_match().
+
+	* test/ruby/test_string.rb: Test for above.
+
+	* vm.c (vm_init_redefined_flag): Add BOP flag for String#=~
+
+	[ruby-core:57385] [Bug #8953]
+
 Thu Sep 26 16:43:42 2013  Akinori MUSHA  <knu@iDaemons.org>
 
 	* misc/ruby-electric.el: Avoid use of the interactive function
diff --git a/insns.def b/insns.def
index a73501f245..740ff5dfa7 100644
--- a/insns.def
+++ b/insns.def
@@ -2098,7 +2098,8 @@ opt_regexpmatch2
 (VALUE obj2, VALUE obj1)
 (VALUE val)
 {
-    if (RB_TYPE_P(obj2, T_STRING)) {
+    if (RB_TYPE_P(obj2, T_STRING) &&
+	BASIC_OP_UNREDEFINED_P(BOP_MATCH, STRING_REDEFINED_OP_FLAG)) {
 	val = rb_reg_match(obj1, obj2);
     }
     else {
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index 4520464105..694d122372 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -2256,6 +2256,18 @@ class TestString < Test::Unit::TestCase
     assert_equal Encoding::UTF_8, a.encoding
     assert_equal Encoding::US_ASCII, b.encoding
   end
+
+  def test_eq_tilde_can_be_overridden
+    assert_in_out_err([], <<-RUBY, ["foo"], [])
+      class String
+        def =~(str)
+          "foo"
+        end
+      end
+
+      puts "" =~ //
+    RUBY
+  end
 end
 
 class TestString2 < TestString
diff --git a/vm.c b/vm.c
index d647ab4a2a..a43f3d6b20 100644
--- a/vm.c
+++ b/vm.c
@@ -1095,7 +1095,7 @@ vm_init_redefined_flag(void)
     OP(Size, SIZE), (C(Array), C(String), C(Hash));
     OP(EmptyP, EMPTY_P), (C(Array), C(String), C(Hash));
     OP(Succ, SUCC), (C(Fixnum), C(String), C(Time));
-    OP(EqTilde, MATCH), (C(Regexp));
+    OP(EqTilde, MATCH), (C(Regexp), C(String));
 #undef C
 #undef OP
 }