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baqlast Wednesday at 12:01 PM2 repliesview on HN

> I don't know what one should even make from that statement.

it's just a fact. by definition of the Rust language unsafe Rust is approximately as safe as C (technically Rust is still safer than C in its unsafe blocks, but we can ignore that.)

> you didn't even bother to look at the code but still presented

of course I did, what I've seen were one-liner trait impls (the 'whole traits' from your own post) and sub-line expressions of unsafe access to bindings.


Replies

zozbot234last Wednesday at 12:20 PM

> technically Rust is still safer than C in its unsafe blocks

This is quite dubious in a practical sense, since Rust unsafe blocks must manually uphold the safety invariants that idiomatic Safe Rust relies on at all times, which includes, e.g. references pointing to valid and properly aligned data, as well as requirements on mutable references comparable to what the `restrict` qualifier (which is rarely used) involves in C. In practice, this is hard to do consistently, and may trigger unexpected UB.

Some of these safety invariants can be relaxed in simple ways (e.g. &Cell<T> being aliasable where &mut T isn't) but this isn't always idiomatic or free of boilerplate in Safe Rust.

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menaeruslast Wednesday at 12:31 PM

So, unsafe block every 70 LoC in 1500 LoC toy example? Sure, it's a strong argument.

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