Luke Gruber de2c2bd60f
Take VM lock in class_switch_superclass (#15356)
Safe multi-ractor subclass list mutation

We need to lock around mutation and accesses of a class's subclasses
list. Unfortunately we also need to do this when creating singleton
classes, as the singleton class does need to go into `super`'s
subclasses list for CC invalidation purposes.
2025-12-04 16:10:21 -05:00
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