Insightful article. As they say doubly linked lists are approximately useless and never used. But trees were nodes can refer to their parents are extremely common.

And I agree, a custom arena is usually the best option here. Even though it seems like "giving up" and going back to C, it's still way better.

There's this great comparison of Arenas in Rust: https://donsz.nl/blog/arenas/

Some of them have keys that can't be reused too, so you can avoid "use after free" style bugs (at runtime) which is way better than C pointer wrangling.

It's not perfect though. I kind of wish Rust did have some kind of support for this stuff natively. Pretty low on my list of Rust desires though - way behind better compile time and fewer async footguns.