trophy-case VS slotmap

You could check cargo-fuzz trophy case, which is a list of issues that have been found via fuzzing.

I've added it to the trophy case.

That said, what's present in what quantities under what circumstances in the Rust fuzzing trophy case does a pretty good job of illustrating how effective the Rust compiler is at ruling out entire classes of bugs.

The same fuzzing techniques applied to Rust yielded a lot of bugs as well. But in Rust's case only 7 out of 340 fuzzer-discovered bugs, or 2%, were memory corruption issues. Naturally, all of the memory corruption bugs were in unsafe code.

https://github.com/rust-fuzz/trophy-case has like 70 of my issues in it, including the nine minidump bugs

If you have found any bugs with this tool, perhaps add them to the Rust fuzz trophy case?

Source: https://github.com/rust-fuzz/trophy-case (over 40 of those are just from me).

But to bring some data, check out the fuzz trophy case. It shows that failures in Rust are most often assertions/panics (equivalent to C++ exception) with memory corruption being relatively rare (it's not never—Rust isn't promising magic—but it's a significant change).

You need to read the list more carefully.

• The list is not for Rust itself, but every program every written in Rust. By itself it doesn't mean much, unless you compare prevalence of issues among Rust programs to prevalence of issues among C programs. For some context, see how memory unsafety is rare compared to assertions and uncaught exceptions: https://github.com/rust-fuzz/trophy-case

• Many of the memory-unsafety issues are on the C FFI boundary, which is unsafe due to C lacking expressiveness about memory ownership of its APIs (i.e. it shows how dangerous is to program where you don't have the Rust borrow checker checking your code).

• Many bugs about missing Send/Sync or evil trait implementations are about type-system loopholes that prevented compiler from catching code that was already buggy. C doesn't have these guarantees in the first place, so lack of them is not a CVE for C, but just how C is designed.

It looks like .get_disjoint_mut() from slotmap failed under stacked borrows, but seems to pass under tree borrows

I think slotmap is meant to solve this exact issue. Basically when you insert into a collection you get an Id:Version tuple as key. When you reuse a slot, next time the key will be Id:Version+1 and when you try to access the removed value by using Id:Version, it will return None. You can think about it as delayed invalidation.

Dunno about existing implementations, but it looks like it's a feature they'd accept: https://github.com/orlp/slotmap/issues/73

It's actually quite easy.

You can use either slot map or slab to side step rust borrow checker. Example https://github.com/orlp/slotmap/blob/master/examples/rand_meld_heap.rs

I don't know, only have some theories.

1. The name isn't particularly catchy or descriptive. It is the correct name for the data structure, but not too many people know the data structure.

2. People don't even know what they're missing. It's not a very Google-able problem to begin with. Slotmap provides an interesting solution to (circular) ownership and safe allocator / weak pointer design problems, but people don't recognize that they're having them or that slotmap could help.

As an example of this, the doubly linked list example (https://github.com/orlp/slotmap/blob/master/examples/doubly_...) can safely remove nodes from the linked list given their handle, in O(1), even from the middle, completely safely and correctly, even in the presence of double deletions or ABA memory re-use. You can't replicate this with just pointers, without introducing heavy refcounting solutions.

Nope, it's perfectly safe: https://github.com/orlp/slotmap/blob/master/examples/doubly_linked_list.rs.

I think keeping the relationship between child and parent elements in the node graph might be better accommodating better via a psuedo-ECS system, see https://www.reddit.com/r/rust/comments/cnjhup/idiomatic_way_to_reference_parent_struct/. The https://github.com/orlp/slotmap crate looks promising. I think I'm just going to ditch the global shared HashMap in favor of something that can better accommodate child/parent relations.

I think the slotmap crate is similar to what you're trying to write: https://github.com/orlp/slotmap