* ext/psych/lib/psych/visitors/yaml_tree.rb: dump empty symbols with a

tag so that they can be parsed on input. [Bug #9873] [ruby-core:62825]
* test/psych/test_symbol.rb: test for change

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46358 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Fri Jun  6 07:41:41 2014  Aaron Patterson <aaron@tenderlovemaking.com>
+
+	* ext/psych/lib/psych/visitors/yaml_tree.rb: dump empty symbols with a
+	  tag so that they can be parsed on input. [Bug #9873] [ruby-core:62825]
+	* test/psych/test_symbol.rb: test for change
+
 Thu Jun  5 16:08:39 2014  Koichi Sasada  <ko1@atdot.net>
 
 	* gc.c (gc_page_sweep): refactoring.

ext/psych/lib/psych/visitors/yaml_tree.rb

@@ -378,7 +378,11 @@ module Psych
       end
 
       def visit_Symbol o
-        @emitter.scalar ":#{o}", nil, nil, true, false, Nodes::Scalar::ANY
+        if o.empty?
+          @emitter.scalar "", nil, '!ruby/symbol', false, false, Nodes::Scalar::ANY
+        else
+          @emitter.scalar ":#{o}", nil, nil, true, false, Nodes::Scalar::ANY
+        end
       end
 
       private

test/psych/test_symbol.rb

@@ -2,6 +2,14 @@ require_relative 'helper'
 
 module Psych
   class TestSymbol < TestCase
+    def test_cycle_empty
+      assert_cycle :''
+    end
+
+    def test_cycle_colon
+      assert_cycle :':'
+    end
+
     def test_cycle
       assert_cycle :a
     end