AuthorizationHandle::challenge lifetime issue

[beviu]

Hi,

The signature for AuthorizationHandle::challenge is:

instant-acme/src/order.rs

Line 397 in 1cc1b82

pub fn challenge(&'a mut self, r#type: ChallengeType) -> Option<ChallengeHandle<'a>> {

I am trying to write code that reads from the authorization after I'm done with the challenge:

use instant_acme::{Authorization, ChallengeType};

fn main() {
    let authorization: Authorization = todo!();
    let Some(challenge) = authorization.challenge(ChallengeType::Dns01) else {
        eprintln!(
            "Missing DNS-01 challenge for authorization {:?}",
            authorization.identifier().identifier
        );
        return;
    };
    println!("Challenge identifier: {:?}", challenge.identifier());
}

This code does not compile. I think it is because, in challenge, the lifetime of the mutable reference to the AuthorizationHandle<'a> is forced to be the maximum lifetime 'a.

Would it be possible to use a different lifetime 'a: 'b instead of 'a here? I tested the following patch and it makes the code above work:

-    pub fn challenge(&'a mut self, r#type: ChallengeType) -> Option<ChallengeHandle<'a>> {
+    pub fn challenge(&mut self, r#type: ChallengeType) -> Option<ChallengeHandle<'_>> {

[djc]

What are you trying to achieve? What's the use case here?

[beviu]

I'm trying to add error handling in case the challenge is not present. I thought I could print something like: "Missing challenge for authorization for example.com". This is not an error I've actually hit.

I was wondering if the lifetime was chosen on purpose. If it is, to make sure we don't use the AuthorizationHandle again after we call challenge, then all is fine. I can understand the decision and work around it.

[djc]

Feel free to fiddle with the lifetimes and see if you can come up with something that works for you. I didn't intentionally use longer lifetimes than strictly need, just used the simplest formulation I could come up with that compiled.