Specify AppLabel for SyncComponent / ExtractComponent / ExtractResource

[Zeophlite]

Objective

• Step towards making the extract infra is reusable for non-rendering crates (see bevy_extract tracking #24483 )
• There is two ways to set a component as extractable from the main world to the render world, #[derive(ExtractComponent)] (preferentially) , or impl ExtractComponent for Foo {} (similarly for ExtractResource and SyncComponent ) . To make extraction possible to different sub-apps, we need to mark all these as explicitly for RenderApp

Solution

• Allow ExtractComponent , ExtractResource and SyncComponent to specify the AppLabel the trait is implemented for. The corresponding plugin is only implemented for RenderApp .
• For each explicit impl, specify RenderApp , e.g. impl ExtractComponent<RenderApp> for Foo {}
• For each derive ExtractComponent and ExtractResource , specify the AppLabel with the attribute #[extract_app(RenderApp)]

Reviewer Notes

Wow 64 files changed! But it's really just 7 files, the rest is mechanical

• _release-content/migration-guides/extract-extract-b.md - summarises the changes in the rest of the files
• crates/bevy_render/macros/src/extract_component.rs - changes to derive(ExtractComponent)
• crates/bevy_render/macros/src/extract_resource.rs - changes to derive(ExtractResource)
• crates/bevy_render/macros/src/lib.rs - changes to macro call sites
• crates/bevy_render/src/extract_component.rs - changes to ExtractComponent trait
• crates/bevy_render/src/extract_resource.rs - changes to ExtractResource trait
• crates/bevy_render/src/sync_component.rs - changes to SyncComponent trait

I suggest first reading the ExtractResource changes as a starting point

Testing

• CI
• cargo run --example animated_mesh

[kfc35]

looks good to me

[kfc35]

Approving but trusting you’ll clean up some of the docs that might be outdated for the affected structs