1 files changed, 22 insertions, 0 deletions
diff --git a/js/src/tests/non262/async-functions/duplicate-__proto__.js b/js/src/tests/non262/async-functions/duplicate-__proto__.js
new file mode 100644
index 0000000000..d60b052484
--- /dev/null
+++ b/js/src/tests/non262/async-functions/duplicate-__proto__.js
@@ -0,0 +1,22 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Async arrow function parameters.
+async ({__proto__: a, __proto__: b}) => {};
+
+// Async arrow function parameters with defaults (initially parsed as destructuring assignment).
+async ({__proto__: a, __proto__: b} = {}) => {};
+
+// Duplicate __proto__ in CoverCallExpressionAndAsyncArrowHead, but not AsyncArrowHead.
+assertThrowsInstanceOf(() => eval(`
+    NotAsync({__proto__: a, __proto__: b});
+`), SyntaxError);
+
+// Starts with "async", but not called from AssignmentExpression.
+assertThrowsInstanceOf(() => eval(`
+    typeof async({__proto__: a, __proto__: b});
+`), SyntaxError);
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);