Rework the Entry API

[Amanieu]

The main change in this PR is that OccupiedEntry no longer holds the
key used in the initial entry call. As a result, OccupiedEntryRef is
no longer required since OccupiedEntry can be used in EntryRef
directly.

The following methods have been removed:

// hash_map

impl OccupiedEntry {
    fn replace_entry(self, value: V) -> (K, V);
    fn replace_key(self) -> K;
}

impl EntryRef {
    fn and_replace_entry_with<F>(self, f: F) -> Self;
}

impl VacantEntryRef {
    fn into_key(self) -> K;
}

// hash_set

impl Entry {
    fn replace(self) -> T;
}

The following methods have been added:

impl VacantEntry {
    fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V, S, A>;
}

The following methods have their signatures changed:

impl EntryRef {
    // Previously returned OccupiedEntryRef
    fn insert(self, value: V) -> OccupiedEntry<'a, K, V, S, A>;
}

impl VacantEntryRef {
    // Previously returned &Q
    fn key(&self) -> &'b Q;

    // Previously returned OccupiedEntryRef
    fn insert(self, value: V) -> OccupiedEntry<'a, K, V, S, A>;
}

[bors]

☔ The latest upstream changes (presumably #534) made this pull request unmergeable. Please resolve the merge conflicts.

[Amanieu]

@bors r+

[bors]

📌 Commit 731dfcc has been approved by Amanieu

It is now in the queue for this repository.

[bors]

⌛ Testing commit 731dfcc with merge f1ba3b4...

[bors]

☀️ Test successful - checks-actions
Approved by: Amanieu
Pushing f1ba3b4 to master...

[jwiesler]

How would I keep the key after this change if the key already existed in the map? entry and try_insert both take the key by value but don't return it if the key was already in the map, so I used replace_key which does not exist any more.

[Amanieu]

Have you tried using the entry_ref API?

[jwiesler]

Ah, interesting, didn't know about this one thanks. Is there anything I can read up on why it was done this way? The two APIs seem very similar to me.

[Amanieu]

It's a separate API for cases where you want to move the key into the map or make a copy of an existing key without moving it.

[clarfonthey]

Currently working on updating hashbrown for the standard library, and does the removal of the replace_entry API mean that there was the decision to remove it on the Rust side as well? Or was it a mistake to remove it from the RustcOccupiedEntry?

EDIT: I see, the FCP did decide to close, so, I'll remove it.