MapEntities is not implemented for nested types in collections.

[andriyDev]

What problem does this solve or what need does it fill?

The following does not currently compile:

#[derive(Serialize, Deserialize, MapEntities)]
struct PlayerSaveData {
  entity: Entity,
  position: Vec2,
  velocity: Vec2,
}

#[derive(Serialize, Deserialize, MapEntities)]
struct PlayerSaveStage(#[entities] Vec<PlayerSaveData>);

The problem is that Vec<PlayerSaveData> does not implement MapEntities. Vec<Entity> does however. This means I have to manually implement MapEntities for PlayerSaveStage even though it's incredibly trivial.

What solution would you like?

Implement MapEntities for Vec<T> where T: MapEntities. This should automatically work for Entity since Entity: MapEntities.

[andriyDev]

This was actually already implemented in #19071. My mistake!