* vm_insnhelper.c (vm_yield_setup_block_args): partially revert r41019.

The code is not useless.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41041 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Mon Jun  3 03:40:29 2013  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* vm_insnhelper.c (vm_yield_setup_block_args): partially revert r41019.
+	  The code is not useless.
+
 Mon Jun  3 01:25:25 2013  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
 
 	* test/socket/test_sockopt.rb: change test name. follow r41037.

test/ruby/test_yield.rb

@@ -379,4 +379,15 @@ class TestRubyYieldGen < Test::Unit::TestCase
     }
   end
 
+  def test_block_with_mock
+    y = Object.new
+    def y.s(a)
+      yield(a)
+    end
+    m = Object.new
+    def m.method_missing(*a)
+      super
+    end
+    assert_equal [m, nil], y.s(m){|a,b|[a,b]}
+  end
 end

vm_insnhelper.c

@@ -2211,6 +2211,9 @@ vm_yield_setup_block_args(rb_thread_t *th, const rb_iseq_t * iseq,
 
 	MEMCPY(argv, RARRAY_PTR(ary), VALUE, argc);
     }
+    else {
+	argv[0] = arg0; /* rb_check_array_type(arg0) may change argv */
+    }
 
     /* keyword argument */
     if (iseq->arg_keyword != -1) {