On Mon, Feb 28 2022, Tao Klerks via GitGitGadget wrote:

I think squashing 2/2 inot this would make this much easier to follow,
i.e. to have tests along with the new feature.

+	/*
+	 * This check does not apply to the BRANCH_TRACK_INHERIT
+	 * option; you can inherit one or more tracking entries
+	 * and the tracking.matches counter is not incremented.
+	 */
 	if (tracking.matches > 1)
 		die(_("not tracking: ambiguous information for ref %s"),
 		    orig_ref);

This function is the only user of find_tracked_branch(). For e.g. "git
checkout we emit";

    fatal: builtin/checkout.c:1246: 'foo' matched multiple (4) remote tracking branches

Perhaps we can do something similar here, and even with some advise()
emit information about what other branches conflicted.

+	if (track == BRANCH_TRACK_SIMPLE) {
+		/*
+		 * Only track if remote branch name matches.
+		 * Reaching into items[0].string is safe because
+		 * we know there is at least one and not more than
+		 * one entry (because not BRANCH_TRACK_INHERIT).
+		 */
+		const char *tracked_branch;
+		if (!skip_prefix(tracking.srcs->items[0].string,
+				 "refs/heads/", &tracked_branch) ||
+		    strcmp(tracked_branch, new_ref))
+			return;
+	}
+

I wondered when reading this if there isn't a way to merge this and the
"branch_get" call made in "inherit_tracking" earlier in this function in
the "track != BRANCH_TRACK_INHERIT" case.

But maybe not, and that whole API entry point is a bit messy in needing
to cover both the use-case of an existing branch & nonexisting
(i.e. initial creation).