2 files changed, 29 insertions, 0 deletions
diff --git a/test/-ext-/array/test_to_ary_concat.rb b/test/-ext-/array/test_to_ary_concat.rb
new file mode 100644
index 0000000000..feb1bc1109
--- /dev/null
+++ b/test/-ext-/array/test_to_ary_concat.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: false
+require 'test/unit'
+require '-test-/array/to_ary_concat'
+
+class TestConcatStress < Test::Unit::TestCase
+  def setup
+    @stress_level = GC.stress
+    GC.stress = true
+  end
+
+  def teardown
+    GC.stress = @stress_level
+  end
+
+  def test_concat
+    arr = [nil]
+    bar = Bug::Bar.new
+    arr.concat(bar)
+  end
+end
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index 26d40fcc6b..30bf13795c 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -654,6 +654,15 @@ class TestArray < Test::Unit::TestCase
 
     assert_raise(TypeError) { [0].concat(:foo) }
     assert_raise(FrozenError) { [0].freeze.concat(:foo) }
+
+    a = @cls[nil]
+    def (x = Object.new).to_ary
+      ary = Array.new(2)
+      ary << [] << [] << :ok
+    end
+    EnvUtil.under_gc_stress {a.concat(x)}
+    GC.start
+    assert_equal(:ok, a.last)
   end
 
   def test_count