Blender Git Loki

Fix T83280: Crash when deleting hair collision collection.

Root of the issue was missing management of ID pointers in the cloth
modifier data stored in ParticleSystem for hair physics, in the
'foreach_id' particle system code.

Using modifier's 'foreach_id' code in psys one unfortunately requires
some ugly conversion gymnastics, but this is still better than having
dedicated code for that case.

Note that this is actually a fairly critical issue, fix should be
backported to 2.91.1 should we do it, and to 2.83 LTS as well I think.