Fix unnamed workflow on pull request

[dbalcomb]

This attempts to fix the issue where the check run appears under (Unnamed workflow) in the actions tab when triggered by a pull request.

Examples of this can be found on the following repositories:

• actix/actix
• bastion-rs/bastion
• tokio-rs/tracing

It appears that the reason is due to the pull request workflow running on a short-lived merge commit. When the UI tries to display the workflow it shows as (Unknown event) and (Unnamed workflow) because it cannot find any reference to the commit SHA.

Fortunately the context payload includes the pull request information so this simply changes the check to use the pull request head SHA when available.

I have successfully tested this on a pull request workflow but it might need some further testing. Specifically according to the event types & payloads documentation there are pull request review and pull request review comment events which also include the pull request in the payload. According to the events that trigger workflows they also use a merge commit. I suppose that it cannot hurt as if there is no merge commit then the default SHA will be the same as the pull request head SHA.

This may also be related to #45.

[fbecart]

My project is having the same issue https://github.com/fbecart/zinoma/actions
Of course it's not blocking, but a fix would be welcome.

@dbalcomb Can I help testing this PR? If so, could you give me some indication how to proceed?

[dbalcomb]

@fbecart After some further thought I don't think that additional testing is necessary but it would be good to get input from the developer of the action.

@svartalf Could you take a look at this? I see that you are working on the actions-rs/clippy action as a replacement for this one. I am not entirely sure how it differs but it would be good to see this fix landed in the meantime. Assuming that you approve of course.

[svartalf]

Hey, @dbalcomb! Sorry for not getting back to you earlier.

In a current state actions-rs/clippy is nothing more than an experiment; I wanted to check if it would be possible right not do the same what this Action does, but without requiring GITHUB_TOKEN and communicating with GH API.
It's kinda possible by abusing undocumented things, but whole approach is very ugly overall, so it's not like this Action will be deprecated soon and your fix is definitely an amazing finding!

It looks fine for me, so I'll merge and publish it tomorrow. Thank you for debugging this thing :)

[pitkley]

I quickly wanted to mention that I tested this PR and can confirm that the annotations are now associated with the correct check for pull-requests. 👍

[svartalf]

This fix was published in v1.0.7 and can be used now as latest actions-rs/clippy-check@v1 tag.