parse.y: empty hash in defined

* parse.y (command): NODE_ARRAY with NULL is invalid.  traversal
  in defined_expr0 is simplified than iseq_compile_each0.
  [ruby-core:82113] [Bug #13756]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59375 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

parse.y

@@ -2293,7 +2293,7 @@ call_args	: command
 		| assocs opt_block_arg
 		    {
 		    /*%%%*/
-			$$ = NEW_LIST($1 ? new_hash($1) : 0);
+			$$ = $1 ? NEW_LIST(new_hash($1)) : 0;
 			$$ = arg_blk_pass($$, $2);
 		    /*%
 			$$ = arg_add_assocs(arg_new(), $1);

test/ruby/test_syntax.rb

@@ -169,10 +169,16 @@ class TestSyntax < Test::Unit::TestCase
   end
 
   def test_keyword_empty_splat
-    assert_separately([], <<-'end;')
+    assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}")
+    begin;
       bug10719 = '[ruby-core:67446] [Bug #10719]'
       assert_valid_syntax("foo(a: 1, **{})", bug10719)
     end;
+    assert_separately([], "#{<<-"begin;"}\n#{<<-'end;'}")
+    begin;
+      bug13756 = '[ruby-core:82113] [Bug #13756]'
+      assert_valid_syntax("defined? foo(**{})", bug13756)
+    end;
   end
 
   def test_keyword_self_reference