Hmm. The example in the article involves overlapping references to .cache and .template. I’m not seeing how owned guard protections would make sense.

I can maybe see how one might have a MutexGuard for the entire RenderState and then pass an owned MutexGuard<PartOfTheState> somewhere else, but this seems like it should not be necessarily be able to coexist with other guards holding the same mutex.

How would split guards work, anyway? Reference counts on parts of the mutex? Would the mutex have to opt in? Is there an actual example where splitting a mutex guard would be useful!