From 3f9562015e651735bfc2fdd14e8f6963b673e22a Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Sat, 27 Apr 2019 21:21:55 +0900
Subject: Get rid of indirect sharing

* string.c (str_duplicate): share the root shared string if the
  original string is already sharing, so that all shared strings
  refer the root shared string directly.  indirect sharing can
  cause a dangling pointer.

[Bug #15792]
---
 test/ruby/test_string.rb | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'test/ruby/test_string.rb')

diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index d94c4da7ae..f591f7ea9d 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -2961,6 +2961,15 @@ CODE
   end
 =end
 
+  def test_nesting_shared
+    a = ('a' * 24).encode(Encoding::ASCII).gsub('x', '')
+    hash = {}
+    hash[a] = true
+    assert_equal(('a' * 24), a)
+    4.times { GC.start }
+    assert_equal(('a' * 24), a, '[Bug #15792]')
+  end
+
   def test_shared_force_encoding
     s = "\u{3066}\u{3059}\u{3068}".gsub(//, '')
     h = {}
-- 
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