Change OccupiedEntry/RawOccupiedEntryMut lifetimes

[ChosenName]

Changes the lifetimes returned by key(_mut), get(_mut) and entry(_mut) to 'a. This makes the returned value valid for the lifetime of the hash map which makes returning them valid.

Example

use hashbrown::HashMap;

fn get_and_insert<'a>(map: &'a mut HashMap<String, String>, key: String, value: String) -> &'a String {
    map.raw_entry_mut()
        .from_key(&key)
        .insert(key, value)
        get()
}

[Amanieu]

This is incorrect because it would cause the returned lifetime to still be valid even after the entry is removed.

[clarfonthey]

Yeah, this is why you need into_key_mut to get the original lifetimes back.