hash.c: fix segv in Hash#replace

* hash.c (rb_hash_replace): fix segv on `{}.replace({})` introduced
  in r44060 [Bug #9230] [ruby-core:58991]
* test/ruby/test_hash.rb: regression test for above

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44096 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 10 insertions, 0 deletions

diff --git a/test/ruby/test_hash.rb b/test/ruby/test_hash.rb
index 0593785148..afb0ca4805 100644
--- a/test/ruby/test_hash.rb
+++ b/test/ruby/test_hash.rb
@@ -592,6 +592,16 @@ class TestHash < Test::Unit::TestCase
     assert_nil(h[2])
   end
 
+  def test_replace_bug9230
+    h = @cls[]
+    h.replace(@cls[])
+    assert_empty h
+
+    h = @cls[]
+    h.replace(@cls[].compare_by_identity)
+    assert_predicate(h, :compare_by_identity?)
+  end
+
   def test_shift
     h = @h.dup