From 15ef28a991f66f65bb29751cf2bef3bcb51066fc Mon Sep 17 00:00:00 2001
From: normal <normal@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Sat, 25 Feb 2017 02:31:03 +0000
Subject: [PATCH] NEWS: document String#-@ change

* test/ruby/test_string.rb (test_uplus_minus): test deduplication
  [ruby-core:79747] [Feature #13077]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57710 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 NEWS                     | 5 +++++
 test/ruby/test_string.rb | 2 ++
 2 files changed, 7 insertions(+)

diff --git a/NEWS b/NEWS
index 33268b8762..2a0413f006 100644
--- a/NEWS
+++ b/NEWS
@@ -28,6 +28,11 @@ with all sufficient information, see the ChangeLog file or Redmine
 
   * Thread#fetch  [Feature #13009]
 
+* String
+
+  * String#-@ deduplicates unfrozen strings.  Already-frozen
+    strings remain unchanged for compatibility.  [Feature #13077]
+
 === Stdlib updates (outstanding ones only)
 
 === Compatibility issues (excluding feature bug fixes)
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index d5166a82bc..da8bd5f05a 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -2537,6 +2537,8 @@ CODE
 
     assert_not_equal(str.object_id, (+str).object_id)
     assert_equal(str.object_id, (-str).object_id)
+    bar = %w(b a r).join('')
+    assert_same(str, -bar, "uminus deduplicates [Feature #13077]")
   end
 
   def test_ord