>>105283463
>You don't need raw pointers to avoid locking and/or reference counting.
The purest case of this is RefCell, which typically just asserts at runtime what could not be proven at compile time.
It's also common to use Rc or Arc in cases where you know how long a value will live but it's too hard to communicate this to the type system.
>In Rust you rarely explicitly index slices. You generally use iterators.
Iterators are nice and all but indexing is still extremely common. Not everything is a loop.
>What would you need uninitialized memory for?
A very common case is I/O buffers. You initialize one by writing into it, often using a syscall, and then you want to read from the part that was initialized.
The easy and Rust-safe way is to fill the whole buffer with zeroes first. That's expensive.
The efficient but unsafe way is to use a MaybeUninit slice.
>Use Into
Not every type implements From for every other type.
Sometimes you want to e.g. map some bytes from the disk and interpret those bytes as structs without copying them. To do that with just the stdlib you need transmute.
There's a lot of ongoing work to make many cases possible using safe code. Check out bytemuck and zerocopy and project safe transmute. But right now you still need unsafe code, or a crate that wraps unsafe code.
>Once you construct a string it does no further validation.
Say you call String::from_utf8_lossy() on a borrowed Vec<u8> and it returns a Cow::Borrowed(&str). You now know that the Vec<u8> contains valid UTF-8, but to turn it into a String without copying it or repeating the validation you need String::from_utf8_unchecked().
There are other cases but I keep running into that one.
>That doesn't sound performance related.
Not necessarily, but you may see e.g. unsafe impl Sync in ambitious multithreaded code.
>Never seen anyone do this personally.
Check out the internals of std::io::Error. Or this crate: https://docs.rs/compact_str/latest/compact_str/#how-it-works

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>rav1d is a rust rewrite of dav1d>rust code is transpiled from C code and then refactored into "safe" rust code>re-uses the…

>rav1d is a rust rewrite of dav1d
>rust code is transpiled from C code and then refactored into "safe" rust code
>re-uses the…