[adrian17]

Just for reference, the gc-arena crate (https://github.com/kyren/gc-arena) we use in Ruffle's Actionscript 1/2/3 interpreters and across the entire engine, does this. As far as we know, it's safe and sound, at the cost of some limitations, mainly: to compile-time prevent sweeping while holding onto Gc references, every struct and function touching Gc objects passes an extra 'gc lifetime. And not being able to run the GC at arbitrary time can be major issue depending on what you're doing; in Ruffle we incrementally collect between frames and pray that no single frame will ever allocate enough to OOM in the middle of it :)

And yeah, RefCells everywhere.

[ltungv]

Thanks a lot for the insight. I think if I do it the way shifgrethor did, I can have GC at arbitrary time. But I'm not so sure about that.

With the way Rust may perform optimizations on the assumption of no alias, I guess there's currently no way to avoid RefCell if we want to be 100% on the safe side.