1 files changed, 89 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/arguments/bug1762575-3.js b/js/src/jit-test/tests/arguments/bug1762575-3.js
new file mode 100644
index 0000000000..371eab009f
--- /dev/null
+++ b/js/src/jit-test/tests/arguments/bug1762575-3.js
@@ -0,0 +1,89 @@
+// Test implementation details when arguments object keep strong references
+// to their elements.
+
+function checkWeakRef(f, isCleared = true) {
+  let [wr, args] = f({});
+
+  assertEq(wr.deref() !== undefined, true);
+
+  clearKeptObjects();
+  gc();
+
+  // In an ideal world, the reference is always cleared. But in specific
+  // circumstances we're currently keeping the reference alive. Should this
+  // ever change, feel free to update this test case accordingly. IOW having
+  // |isCleared == false| is okay for spec correctness, but it isn't optimal.
+  assertEq(wr.deref() === undefined, isCleared);
+}
+
+checkWeakRef(function() {
+  // Create a weak-ref for the first argument.
+  let wr = new WeakRef(arguments[0]);
+
+  // Clear the reference from the arguments object.
+  arguments[0] = null;
+
+  // Let the arguments object escape.
+  return [wr, arguments];
+});
+
+checkWeakRef(function() {
+  // Create a weak-ref for the first argument.
+  let wr = new WeakRef(arguments[0]);
+
+  // Clear the reference from the arguments object.
+  Object.defineProperty(arguments, 0, {value: null});
+
+  // Let the arguments object escape.
+  return [wr, arguments];
+});
+
+checkWeakRef(function self() {
+  // Create a weak-ref for the first argument.
+  let wr = new WeakRef(arguments[0]);
+
+  // Delete operation doesn't clear the reference!
+  delete arguments[0];
+
+  // Let the arguments object escape.
+  return [wr, arguments];
+}, /*isCleared=*/ false);
+
+checkWeakRef(function() {
+  "use strict";
+
+  // Create a weak-ref for the first argument.
+  let wr = new WeakRef(arguments[0]);
+
+  // Clear the reference from the arguments object.
+  arguments[0] = null;
+
+  // Let the arguments object escape.
+  return [wr, arguments];
+});
+
+checkWeakRef(function() {
+  "use strict";
+
+  // Create a weak-ref for the first argument.
+  let wr = new WeakRef(arguments[0]);
+
+  // This define operation doesn't clear the reference!
+  Object.defineProperty(arguments, 0, {value: null});
+
+  // Let the arguments object escape.
+  return [wr, arguments];
+}, /*isCleared=*/ false);
+
+checkWeakRef(function() {
+  "use strict";
+
+  // Create a weak-ref for the first argument.
+  let wr = new WeakRef(arguments[0]);
+
+  // Delete operation doesn't clear the reference!
+  delete arguments[0];
+
+  // Let the arguments object escape.
+  return [wr, arguments];
+}, /*isCleared=*/ false);