1642685 - WeakRef and FinalizationRegistry should preserve DOM wrappers

Status: RESOLVED FIXED

(Core :: JavaScript: GC, defect)

Description

[Jon Coppeard (:jonco)]

As pointed out by smaug:

does use of WeakRef force preserving wrappers?
since if not, what happens if one does:
  document.body.appendChild(document.createElement("div")); 
  var w = new WeakRef(document.body.lastChild);
document.body.lastChild certainly stays alive there, but its wrapper may die
when GC runs

A user may observe that the wrapper to the DOM object dies, even though the DOM object itself is still alive.

The same issue applies to objects registered with FinalizationRegistry. The solution is to preserve DOM wrappers in this case, the same as we do for WeakMap keys.

Comment 1

[Jon Coppeard (:jonco)]

Attachment: Bug 1642685 - WeakRef and FinalizationRegistry should preserve DOM wrappers r?sfink

Depends on D77267

Comment 2

[Jon Coppeard (:jonco)]

Attachment: Bug 1642685 - Add WeakRef and FinalizationRegistry tests involving DOM objects r?smaug

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/7d6899087a54
WeakRef and FinalizationRegistry should preserve DOM wrappers r=sfink
https://hg.mozilla.org/integration/autoland/rev/8b90826d7abe
Add WeakRef and FinalizationRegistry tests involving DOM objects r=smaug

Comment 4

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/7d6899087a54
https://hg.mozilla.org/mozilla-central/rev/8b90826d7abe