Directional light does not disappear after removing the DirectionalLight component

[tim-blackbird]

Removing the DirectionalLight component does not remove the directional light from the render world

Caused by #15320

Noticed in the clearcoat example

[kristoff3r]

This seems like a general issue we need to solve with the retained render world that the PR/docs doesn't answer, who is responsible for removing components from the render world? Should that be done by the extract step, a separate system/plugin, or is it the users responsibility? A workaround is to remove SyncToRenderWorld and RenderEntity together with the component, but that seems like a footgun.

In any case we really need to fix and/or document it before 0.15.

[alice-i-cecile]

[4:24 PM]kristoff3r: The OIT example is broken with the retained render world in the same way as #15560. How do we plan to support removing components like this?
[4:29 PM]IceSentry: 😦 oh no
[4:30 PM]IceSentry: @bird! @alice 🌹 ^
[4:32 PM]Alice 🌹: Hmm. This is more common than I expected
[4:33 PM]Alice 🌹: My medium-term plan was to do a ref-counting style design, where you have a "number of components that are causing this to be retained" tracked
[4:33 PM]Alice 🌹: And then hooks to incremenet and decrement it
[4:33 PM]Alice 🌹: I think we probably need to prioritize getting that in

From Discord.