(libp2p-identity) Confusing deprecation(s) on making PeerId from ed25519 PublicKey bytes

[DougAnderson444]

Background

Suppose we want to create a new PeerId from someone's public key bytes, we can do this:

use libp2p_identity::ed25519;
use libp2p_identity::PeerId;
use libp2p_identity::PublicKey;

let pub_key = ed25519::PublicKey::decode(pb_bytes)
    .map(PublicKey::Ed25519)
    .unwrap();

let binary_peer_id = PeerId::from_public_key(&pub_key).to_bytes();

Which works as expected ✔️.
...But with a deprecation notice says to use PublicKey::into_ed25519 instead of the PublicKey::Ed25519 enum:

rust-libp2p/identity/src/keypair.rs

Lines 394 to 401 in 96288b8

	pub enum PublicKey {
	/// A public Ed25519 key.
	#[cfg(feature = "ed25519")]
	#[deprecated(
	since = "0.1.0",
	note = "This enum will be made opaque in the future, use `PublicKey::into_ed25519` instead."
	)]
	Ed25519(ed25519::PublicKey),

Which doesn't do the same thing, and also has it's own deprecation direction here:

rust-libp2p/identity/src/keypair.rs

Lines 111 to 118 in 96288b8

	#[cfg(feature = "ed25519")]
	#[deprecated(
	since = "0.2.0",
	note = "This method name does not follow Rust naming conventions, use `Keypair::try_into_ed25519` instead."
	)]
	pub fn into_ed25519(self) -> Option<ed25519::Keypair> {
	self.try_into().ok()
	}

...which is also deprecated since v0.2.0, which is odd because identity is at v0.1.1 🤔 .

THAT deprecation notice says to use Keypair::try_into_ed25519, which doesn't seem to exist.

So I'm sure you can sense my confusion.

The issue is:

It's really confusing as to why the method that works points to 2 others which don't work or don't exist.

Potential Solution

Unless there is a clear reason or working deprecation path, remove the deprecations? I'm not privy to the logic as to why this is all here.

[thomaseizinger]

Sorry for the confusion! Are you depending on master by any chance?

The latter deprecation warnings are not released yet I think?
I agree that the version numbers should be removed though, they are so easy to get wrong if PRs merge in a different order.

You should be able to use .into to promote your ed25519::PublicKey to an identity::PublicKey. That is missing from the deprecation warnings :/

A PR would be much appreciated and sorry for the confusion!

[DougAnderson444]

Thanks @thomaseizinger for understanding and the explanation! I'll send a PR to hopefully clear it up.

I will add impl From<> to PublicKey for the .from/.into to work

[thomaseizinger]

I will add impl From<> to PublicKey for the .from/.into to work

Does that not work already? That was definitely an oversight, sorry for that!

[DougAnderson444]

No worries!

To answer your question about which version I was using, it was 0.1.1 from crates.io

I did try .into() and ::from() but neither worked until I added the impl From, but it's all good!