ref of "HEAD" does not work

[ljharb]

Related to #910, I'd like to be able to default the ref to HEAD so i don't have to hardcode main or master or whatever in a reusable workflow, but instead i get:

  Determining the checkout info
  /usr/bin/git branch --list --remote origin/HEAD
  /usr/bin/git tag --list HEAD
  Error: A branch or tag with the name 'HEAD' could not be found

[rainui28]

Same issue happens when using a commit SHA despite the fact that the README.md specifies

    # The branch, tag or SHA to checkout. When checking out the repository that
    # triggered a workflow, this defaults to the reference or SHA for that event.
    # Otherwise, uses the default branch.
    ref: ''

[ljharb]

For "HEAD", seems like I'd need to make the changes here:

checkout/src/ref-helper.ts

Lines 33 to 60 in b4ffde6

	// refs/heads/
	else if (upperRef.startsWith('REFS/HEADS/')) {
	const branch = ref.substring('refs/heads/'.length)
	result.ref = branch
	result.startPoint = `refs/remotes/origin/${branch}`
	}
	// refs/pull/
	else if (upperRef.startsWith('REFS/PULL/')) {
	const branch = ref.substring('refs/pull/'.length)
	result.ref = `refs/remotes/pull/${branch}`
	}
	// refs/tags/
	else if (upperRef.startsWith('REFS/')) {
	result.ref = ref
	}
	// Unqualified ref, check for a matching branch or tag
	else {
	if (await git.branchExists(true, `origin/${ref}`)) {
	result.ref = ref
	result.startPoint = `refs/remotes/origin/${ref}`
	} else if (await git.tagExists(`${ref}`)) {
	result.ref = `refs/tags/${ref}`
	} else {
	throw new Error(
	`A branch or tag with the name '${ref}' could not be found`
	)
	}
	}

For the sha, it seems like the logic that handles that is here:

checkout/src/input-helper.ts

Lines 63 to 64 in b4ffde6

	result.ref = github.context.ref
	result.commit = github.context.sha

cc @ericsciple; would i need to special-case "HEAD" to look up .git/refs/remotes/origin/HEAD and parse out its ref value and split out what's after refs/remotes/origin/? or is there a cleaner/better way to do it?

[ljharb]

cc @cory-miller?

[mihaigalos]

Seems the HEAD file doesn't exist in the following hierarchy when using the action:

['./.git/refs/remotes/origin/feat', './.git/refs/remotes/origin/fix', './.git/refs/remotes/origin/main']

I would expect a file called .git/refs/remotes/origin/HEAD which contains ref: refs/remotes/origin/main for main.

[ljharb]

cc @jww3?

[AlexAtkinson]

Occasionally I'm reminded of this. Today is one of those occasions. It would be nice if HEAD was included in the GHA environment and showed up when running git show-ref. There's a great deal of script that references it -- ideally, these assets wouldn't have to be adjusted to run in GHA. Thanks.

[saagarjha]

Maybe the best strategy here would be to send in a PR and see what they have to say?