No respond_to? as if the default definition

* vm_method.c (vm_respond_to): try method_missing if respond_to?
  is undefined, as if it is the default definition.
  [ruby-core:75377] [Bug #12353]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55500 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Sat Jun 25 02:33:33 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* vm_method.c (vm_respond_to): try method_missing if respond_to?
+	  is undefined, as if it is the default definition.
+	  [ruby-core:75377] [Bug #12353]
+
 Fri Jun 24 17:04:21 2016  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
 
 	* ext/psych/*, test/psych/*: Upate psych 2.1.0

test/ruby/test_marshal.rb

@@ -737,4 +737,24 @@ class TestMarshal < Test::Unit::TestCase
       end
     RUBY
   end
+
+  MethodMissingWithoutRespondTo = Struct.new(:wrapped_object) do
+    undef respond_to?
+    def method_missing(*args, &block)
+      wrapped_object.public_send(*args, &block)
+    end
+    def respond_to_missing?(name, private = false)
+      wrapped_object.respond_to?(name, false)
+    end
+  end
+
+  def test_method_missing_without_respond_to
+    bug12353 = "[ruby-core:75377] [Bug #12353]: try method_missing if" \
+               " respond_to? is undefined"
+    obj = MethodMissingWithoutRespondTo.new("foo")
+    dump = assert_nothing_raised(NoMethodError, bug12353) do
+      Marshal.dump(obj)
+    end
+    assert_equal(obj, Marshal.load(dump))
+  end
 end

vm_method.c

@@ -1916,7 +1916,7 @@ vm_respond_to(rb_thread_t *th, VALUE klass, VALUE obj, ID id, int priv)
     const rb_method_entry_t *const me =
 	method_entry_get(klass, resid, &defined_class);
 
-    if (!me) return TRUE;
+    if (!me) return -1;
     if (METHOD_ENTRY_BASIC(me)) {
 	return -1;
     }