[Bug] Un-rendering certain components causes memory leak

[bendemboski]

🐞 Describe the Bug

Components meeting a couple of bizarrely specific conditions will leak after being un-rendered. Those conditions are:

1. The component invokes a local helper function from its template
2. The component registers a destructor that references this

🔬 Minimal Reproduction

This repository's scope-pollution-leak branch contains a minimal reproduction of the issue, both via an integration test, and steps for a manual repro in the dummy app.

😕 Actual Behavior

When a component that meets the above conditions is un-rendered, it will not be garbage collected as long as the app is still running.

🤔 Expected Behavior

All components should be garbage collected once they have been un-rendered.

🌍 Environment

• Ember: 5.2.0
• Node.js/npm: 16.15.1
• OS: MacOS
• Browser: Chrome

[bendemboski]

I have verified that the repros in LTSs as far back as Ember 4.4 (although in 4.4 the local helpers have to be wrapped in helper() since Ember didn't yet support plain old functions as helpers).

[acorncom]

Per discussions on Discord (https://discord.com/channels/480462759797063690/485447409296736276/1146624323868692520) Chris Thoburn is going to be posting an update here soon

[bendemboski]

Closing in favor of #20535 which is the issue in Ember -- this issue mixes it together with some weird closure-retaining behavior that's not actually about Ember/Glimmer.