What's the difference between unsync::OnceCell::from and sync::OnceCell::from

[fogti]

Why is the unsync version initialized directly, but the sync version isn't?

unsync:

impl<T> From<T> for OnceCell<T> {
    fn from(value: T) -> Self {
        OnceCell { inner: UnsafeCell::new(Some(value)) }
    }
}

sync:

impl<T> From<T> for OnceCell<T> {
    fn from(value: T) -> Self {
        let cell = Self::new();
        cell.get_or_init(|| value);
        cell
    }
}

[matklad]

this is to save code: there are two sync impls

[fogti]

Couldn't appropriate From impls be added to the two sync impls? They would probably invoke far lesser code than currently (esp. as the code uses atomics and mutexes, which both interactions aren't required in that code path as there is only one owner which can access it).

[matklad]

Yeah, makes sense to do this.