How can you? (genuine question)

I found this project: https://git.sr.ht/~vlmutolo/chainlink

But they use generational indices into a vector. You can't append two doubly-linked lists because they have their own vectors. I was thinking of two separate doubly-linked lists using real pointers (not indices into a vector), but since they were allocated by the same arena allocator, they can be appended.

Is that already possible (in safe Rust)? If so, I guess I should have done more research, sorry :)

Edit: Oh, do you mean the normal one from the standard library? https://doc.rust-lang.org/std/collections/struct.LinkedList....

My bad. I was thinking of something similar, just not implemented with raw pointers underneath, but it already takes an allocator argument in the type, so there would be no benefit to this. Kind of embarrassed now.