Cow from HashMap about rust HOT 4 CLOSED

What From implementation do you expect to exist? I don't understand how Cow, HashMap, and From relate to each other.

from rust.

There are From implementation from various vector-like structs to Cow here but there's nothing similar for HashMap.

If it doesn't make any sense, this issue can be closed, but i was just wondering why

from rust.

HashMap does not have a borrowed form.

we have String and &str, Vec, and [T], but hashmaps always exist on the heap.

you can still put a hashmap in a cow, but this seems incredibly niche:

use std::borrow::Cow;
use std::collections::HashMap;
fn main() {
    let map_inner = HashMap::new();
    let the_map: Cow<'_, HashMap<u8, bool>> = Cow::Borrowed(&map_inner);
}

from rust.

Ohh I see, thanks for the clarification.

We could still benefit from a blanket implementation for T and &T into Cow::Owned and Cow::Borrowed when specialization reaches stable, in order to keep current specialized implementations.

from rust.