Show base commit in PRs (and not just the base branch)

[fregante]

PRs show the base branch, but they don't tell how long ago the current branch was updated. Example:

master         A-B-C-D-E  
                    \     
feature-branch       C-Q-Z    

In this case, this feature would tell us that C is the real base

I've wanted to know this in the past, but at the moment I'm only thinking of why we shouldn't implement this: 😅

• Our update-pr-from-base-branch feature already tells us whether it's up to date and it allows us to update it

Discussion welcome. Would this info be useful? When?

[fregante]

This would use the same API call needed for

• restore-file occasionally restores the wrong commit #4679

[cheap-glitch]

This would use the same API call

Maybe there's a shorter way but this works pretty well:

{
  repository(<...>) {
    pullRequest(number: <number>) {
      commits(first: 1) {
        nodes {
          commit {
            parents(first: 1) {
              nodes { oid }
            }
          }
        }
      }
    }
  }
}

Will try to open a PR today if I can find the time.

[fregante]

@cheap-glitch That doesn't work because it always uses the first commit’s parent, but actually the base can change with a merge commit:

master         A-B-C-D-E-F  
                    \     \
feature-branch       C-Q-Z-Y    

Your query would return C, but GitHub compares the files with F. Our current baseRefOid already updates correctly, except when there's a force push.

For this feature we can use this value for now. My question is just: where do we show this piece of information? restore-file and update-pr-from-base-branch should already have queried all the necessary information here.

[fregante]

where do we show this piece of information?

What if we turn update-pr-from-base-branch into a panel like:

HEAD is 3 commits behind BASE (abcdefg). [Update branch]

This would not appear when the PR is up to date and that's ok.

We'd show the banner regardless of conflicts and native "update branch" buttons. We can preserve this logic just to determine whether to show our Update button:

• Don't show update-pr-from-base-branch when there are conflicts #5768)

[yakov116]

@fregante is this the style you had in mind?

		if (pageDetect.isEnterprise()) {
			position.append(' ', (
				<span className="status-meta d-inline-block rgh-update-pr-from-base-branch">
					You can <button type="button" className="btn-link">update the base branch</button>.
				</span>
			));
		} else {
			position.append(' ', (
				<span className="status-meta d-inline-block">
					{select('.head-ref')!.cloneNode(true)} is {prInfo.headRef.compare.behindBy} commits behind {select('.base-ref')!.cloneNode(true)}
					 {' '}(<a className="btn-link" href={buildRepoURL('commits/' + prInfo.baseRefOid)}>{prInfo.baseRefOid.slice(0, 8)}</a>)
					[<button type="button" className="btn-link rgh-update-pr-from-base-branch">update branch</button>].
				</span>
			));

[fregante]

Love it. I didn't know where to display it, but that makes sense. We can figure out the exact design later

[yakov116]

OK we need to merge #6103 first and then I can work on it