[AS1] Reference to MovieClip is incorrect in Ruffle when MC removed #9257
Description
Describe the bug
I have found a scenario where Flash Player and Ruffle differ. I have produced a MWE here demonstrating the issue.
I first encountered this bug with my game, Zeta Flow. When a laser weapon is destroyed, the red laser that shoots out is also supposed to be removed. (in Flash it is removed; in Ruffle it remains).
This uses:
- Flash version 6 (Flash MX)
- Action Script 1
I tested desktop, self-hosted web, and CDN web versions of Ruffle (on Windows 10). I believe all versions of Ruffle affected.
I narrowed down the problem to a reference to a movie clip that doesn't get cleared when the movie clip is removed. In the MWE below, just follow the steps to reproduce the problem.
Online demo: https://tmp.skylogic.ca/ruffle_MWE/
SWF: https://tmp.skylogic.ca/ruffle_MWE/MWE.swf
FLA: https://tmp.skylogic.ca/ruffle_MWE/MWE.fla
My game (Zeta Flow) relies on this behavior. The laser is supposed to remove itself when the gun is destroyed. In hindsight (15 years later), I could have programmed this differently (and more efficiently) to avoid this. Maybe I'll go and change the code now in order to fix the game! But nonetheless, this highlights a difference in behavior.
Expected behavior
The code boils down to this:
_root.attachMovie("gun", "gun", 0);
_root.attachMovie("laser", "laser", 1);
_root["laser"].gun_reference = _root["gun"];
_root["gun"].removeMovieClip();
In Flash Player, "gun_reference" is correctly empty, but in Ruffle it lives on.
Flash Player:
_root["gun"] =
_root["laser"].gun_reference =
Ruffle:
_root["gun"] =
_root["laser"].gun_reference = _level0.gun
Affected platform
Desktop app
Operating system
Windows 10
Browser
Chrome Version 108.0.5359.126
Additional information
After writing this I looked at some other open issues, and now I'm realizing this issue may be the same as the one identified here and may possibly be resolved by #5492.
I'll post this issue anyway in case it provides a useful test case.