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// 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: --expose-gc --noincremental-marking
let wr;
let wr_control; // control WeakRef for testing what happens without deref
(function () {
let o1 = {};
wr = new WeakRef(o1);
let o2 = {};
wr_control = new WeakRef(o2);
})();
let strong = { a: wr.deref(), b: wr_control.deref() };
// Here and below, we invoke GC synchronously and, with conservative stack
// scanning, there is a chance that the object is not reclaimed now. In any
// case, the WeakRefs should not be cleared.
gc();
// Next task.
setTimeout(function() {
// Call deref inside a closure, trying to avoid accidentally storing a strong
// reference into the object in the stack frame.
(function () { wr.deref(); })();
strong = null;
// This GC should clear wr_control (modulo CSS), since nothing was keeping it
// alive, but it should not clear wr.
gc();
(function () { assertNotEquals(undefined, wr.deref()); })();
// Next task.
(async function () {
// Trigger GC again to make sure the two WeakRefs are cleared.
// We need to invoke GC asynchronously and wait for it to finish, so that
// it doesn't need to scan the stack. Otherwise, the objects may not be
// reclaimed because of conservative stack scanning and the test may not
// work as intended.
await gc({ type: 'major', execution: 'async' });
assertEquals(undefined, wr.deref());
assertEquals(undefined, wr_control.deref());
})();
}, 0);
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