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0 pointscreata11mo ago0 comments

> patterns like using indices instead of pointers which are counter to high performance

Using indices isn't bad for performance. At the very least, it can massively cut down on memory usage (which is in turn good for performance) if you can use 16-bit or 32-bit indices instead of full 64-bit pointers.

> "unsafe" (which is strictly more dangerous than even C, never mind Zig)

Unsafe Rust is much safer than C.

The only way I can imagine unsafe Rust being more dangerous than C is that you need to keep exception safety in mind in Rust, but not in C.

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whytevuhuni11mo ago

Not quite, you also need to keep pointer non-nullness, alignment and aliasing safety in Rust, which is very pervasive in Rust (all shared/mutable references) but very rare in C (the 'restricted' keyword).

In Rust, it's not just using an invalid reference that causes UB, but their very creation, even if temporary. For example, since references have to always be aligned, the compiler can assume the pointer they were created from was also aligned, and so suddenly some ending bits from the pointer are ignored (since they must've been zero).

And usually the point of unsafe is to make safe wrappers, so unafe Rust makes or interacts with safe shared/mutable references pretty often.

creataOP11mo ago

It's just hard for me to imagine someone accidentally messing up nonnullness or aliasing, because it's really in-your-face that you need to be careful when constructing a reference unsafely. There are even idiomatic methods like ptr::as_ref to avoid accidentally creating null references.

j / k navigate · click thread line to collapse

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whytevuhuni11mo ago

And usually the point of unsafe is to make safe wrappers, so unafe Rust makes or interacts with safe shared/mutable references pretty often.

creataOP11mo ago

j / k navigate · click thread line to collapse