Yes, having written a b-tree in rust recently I can confirm this. My child node pointers look like this:

    enum Node<E: EntryTraits, I: TreeIndex<E>> {
        Internal(Pin<Box<NodeInternal<E, I>>>),
        Leaf(Pin<Box<NodeLeaf<E, I>>>),
    }

Yikes. I could probably clean this up a little, but not a lot.

I've been working on this code for months and I still have no idea if my internal b-tree functions should be taking a &mut self, self: Pin<&mut Self> or a NonNull<...> or something else. The compiled code is blazing fast, and being able to control behaviour so clearly with a few parametric type parameters is amazing.

But the process of figuring out the best way to code it up is awful, and it requires all of my attention and capacity. I doubt Rust will ever gain the sort of mainstream usage that javascript & Go have because of how complicated otherwise simple problems can become. Its a great language for the linux kernel and web browsers. But I can't imagine many normal programmers will want to build regular websites and apps in rust.

GC languages are slower, but credit where its due - they make it so much easier to just dive in and spend all your braincells thinking about your problem domain.