Correct possible UB in Arc::drop

rust-lang / nomicon

The Dark Arts of Advanced and Unsafe Rust Programming

https://doc.rust-lang.org/nomicon/

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Correct possible UB in Arc::drop #403

Closed krtab closed 1 year ago

krtab commented 1 year ago

Hi!

I'm not entirely sure but I believe the code as currently presented has potential for UB. Indeed, inner is dropped after the anonymous Box, which means that is is dangling at some point. Iiuc, dangling references are UB in Rust, even if not accessed. In case there is no issue, I think it would be beneficial to explain why in the code comments.

krtab commented 1 year ago

Thanks for the review. For those interested the zulip discussion is here: https://rust-lang.zulipchat.com/#narrow/stream/237824-t-lang.2Fdoc/topic/Review.20for.20https.3A.2F.2Fgithub.2Ecom.2Frust-lang.2Fnomicon.2Fpull.2F403