Bug Advanced use case ISystem codegen bugs

This weekend, I finally got to take advantage of collections being unmanaged and migrated some of my custom command buffer and collection dependency tracking tech to work in Bursted unmanaged systems. Almost everything is working correctly, but I did come across a few surprise bugs.

Bug 1: Discard in idiomatic foreach

Code (CSharp):

1. // Broken
2. foreach ((_, var entity) in Query<RefRO<Faction> >().WithEntityAccess().WithAll<FactionTag>())
3. {
4.     m_factionsCache.Add(latiosWorld.GetCollectionComponent<FactionShipsCollisionLayer>(entity, true));
5.     factionEntities.Add(entity);
6. }
7.  
8. // Works correctly
9. foreach ((var unused, var entity) in Query<RefRO<Faction> >().WithEntityAccess().WithAll<FactionTag>())
10. {
11.     m_factionsCache.Add(latiosWorld.GetCollectionComponent<FactionShipsCollisionLayer>(entity, true));
12.     factionEntities.Add(entity);
13. }

Bug 2: Concrete generic jobs aren't picked up by codegen for early init
Two years ago, there was a hot topic on the forum revolving around the use of generic jobs. That ultimately lead to this repo: https://github.com/Dreaming381/BurstGenericsTest

Anyways, I have been using this pattern since, and it has always worked, except when I tried to use it inside a Burst ISystem. Bug report is IN-19950. If you want a working version of the project, you can find it here, linked to the exact line where I had to comment out [BurstCompile] for one of the systems that was reliant on this pattern: https://github.com/Dreaming381/lsss...tems/Gameplay/ShipVsBulletDamageSystem.cs#L32

Note, the bug report made a mention of another type handle warning issue. I just found the culprit and it is my fault, so ignore that.

 

It happens at line 57. Physics.FindPairs is a generic method which in this case returns a FindPairsLayerLayerConfig<DamageHitShipsAndDestroyBulletsProcessor>. That struct contains a static class called FindPairsInternal. And FindPairsInternal contains a few jobs. The ones we care about here are LayerLayerPart1 and LayerLayerPart2_WithSafety. Those get scheduled back-to-back in ScheduleParallel().

You can clone the project with the linked hash (the hash is the latest commit as I am writing this) and uncomment the [BurstCompile] line and see the error for yourself.