PeerId::from_bytes should be const

[tqwewe]

Description

There's currently no way to create a PeerId in a const context.

Motivation

I'm writing unit tests, and I need a global PeerId shared between tests. A const peer id would be great for this.

Current Implementation

My work around is just to call PeerId::from_bytes every time using the same bytes.

Are you planning to do it yourself in a pull request?

No

[jxs]

Hi, and thanks for the interest!
Making this const depends on multihash so I'd suggest to open an issue there and link it here for tracking purposes.

[tqwewe]

It seems like the only method which is const in multihash is Multihash::wrap. I'm not sure if this is used in libp2p, and lets it be constructed in a const context already? Or if libp2p only uses other multihash methods under the hood which aren't const. If its the latter, then I guess this issue can be closed.

From searching on the multihash repo, I found these two discussions about const:
multiformats/rust-multihash#330
multiformats/rust-multihash#331 (comment)

[dariusc93]

For the time being wouldnt it be possible for you to use LazyLock for the construction of the PeerId that you wish to use in your test?

[tqwewe]

Yes I've resolved it by just using a function returning the same peer id in my tests thanks! But if it's still possible to add const to PeerId I think it's worth keeping the issue open