I have some benchmark results here: https://ivankra.github.io/javascript-zoo/?v8=true

It's impressively compliant, considering it's just a one man project! Almost as fully featured as Boa, plus or minus a few things. And generally faster too, almost double the speed of Boa on some benchmarks.

The whole point of unsafe is to be able to circumvent the guardrails where the developer knows something the compiler isn't (yet) smart enough to understand. It's likely that implementing a high-performance GC runs afoul of quite a few of those edge cases.

The obvious use-case for unsafe is to implement alternative memory regimes that don’t exist in rust already, so you can write safe abstractions over them.

Rust doesn’t have the kind of high performance garbage collection you’d want for this, so starting with unsafe makes perfect sense to me. Hopefully they keep the unsafe layer small to minimise mistakes, but it seems reasonable to me.

Even using something as simple as Vec means using `unsafe` code (from the std library). The idea isn't to have no `unsafe` code (which is impossible). It's to limit it to small sections of your code that are much more easily verifiable.

For some use cases, that means that "user code" can have no `unsafe`. But implementing a GC is very much not one of those.

Rust is not garbage collected though.

> who in the fuck would write a garbage collector using garbage collected Rust?

Rust is not garbage collected unless you explicitly opt into using Rc/Arc