Update to be buildable with Nightly or Stable rust about bacon-rajan-cc HOT 6 CLOSED

I don't think it's safe to trace through the RefCell if it's already borrowed. A Drop implementation could mutate it during cycle collection which will break tracing.

In rust-gc GcCell roots the value in borrow_mut():
https://github.com/Manishearth/rust-gc/blob/e362a0687260534305b2749f986da3f0df1ec356/gc/src/lib.rs#L446

and won't trace through GcCell if it's borrowed:
https://github.com/Manishearth/rust-gc/blob/e362a0687260534305b2749f986da3f0df1ec356/gc/src/lib.rs#L464

from bacon-rajan-cc.

This crate never got fully usable.

At minimum, it needs to have its own fork of RefCell that it can see inside of regardless of borrow status so that it can trace the thing's edges. There are probably a lot more issues than just that, but that's what I remember.

Happy to give collaboratorship / co-ownership if you want to finish this!

from bacon-rajan-cc.

Yeah, I'm some what interested. I got it building here: https://github.com/jrmuizel/bacon-rajan-cc/tree/nightly. I'll try to get it split up into more reviewable chunks and post PRs.

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Can you elaborate a bit more on the RefCell issue?

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If cycle collection kicks in while a refcell is borrowed, it may need to trace through the refcell, but that will assert since it is already borrowed. Need a version that allows tracing regardless whether it is borrowed.

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This is done now.

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