1 files changed, 17 insertions, 0 deletions
diff --git a/deps/v8/test/mjsunit/es9/regress/regress-866357.js b/deps/v8/test/mjsunit/es9/regress/regress-866357.js
new file mode 100644
index 00000000000..3b6230b0f4a
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+++ b/deps/v8/test/mjsunit/es9/regress/regress-866357.js
@@ -0,0 +1,17 @@
+// Copyright 2018 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+// Check that we do appropriate used/unused field accounting
+var p = Promise.resolve();
+var then = p.then = () => {};
+
+function spread() { return { ...p }; }
+
+assertEquals({ then }, spread());
+assertEquals({ then }, spread());
+assertEquals({ then }, spread());
+%OptimizeFunctionOnNextCall(spread);
+assertEquals({ then }, spread());