fetch: backfill tags before setting upstream

The fetch code flow is a bit hard to understand right now:

    1. We optionally prune all references which have vanished on the
       remote side.
    2. We fetch and update all other references locally.
    3. We update the upstream branch in the gitconfig.
    4. We backfill tags pointing into the history we have just fetched.

It is quite confusing that we fetch objects and update references in
both (2) and (4), which is further stressed by the point that we use a
`skip` goto label to jump from (3) to (4) in case we fail to update the
gitconfig as expected.

Reorder the code to first update all local references, and only after we
have done so update the upstream branch information. This improves the
code flow and furthermore makes it easier to refactor the way we update
references together.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

builtin/fetch.c

@@ -1536,7 +1536,7 @@ static void backfill_tags(struct transport *transport, struct ref *ref_map,
 static int do_fetch(struct transport *transport,
 		    struct refspec *rs)
 {
-	struct ref *ref_map;
+	struct ref *ref_map = NULL;
 	int autotags = (transport->remote->fetch_tags == 1);
 	int retcode = 0;
 	const struct ref *remote_refs;
@@ -1620,11 +1620,24 @@ static int do_fetch(struct transport *transport,
 			retcode = 1;
 	}
 	if (fetch_and_consume_refs(transport, ref_map, worktrees)) {
-		free_refs(ref_map);
 		retcode = 1;
 		goto cleanup;
 	}
 
+	/*
+	 * If neither --no-tags nor --tags was specified, do automated tag
+	 * following.
+	 */
+	if (tags == TAGS_DEFAULT && autotags) {
+		struct ref *tags_ref_map = NULL, **tail = &tags_ref_map;
+
+		find_non_local_tags(remote_refs, &tags_ref_map, &tail);
+		if (tags_ref_map)
+			backfill_tags(transport, tags_ref_map, worktrees);
+
+		free_refs(tags_ref_map);
+	}
+
 	if (set_upstream) {
 		struct branch *branch = branch_get("HEAD");
 		struct ref *rm;
@@ -1644,7 +1657,7 @@ static int do_fetch(struct transport *transport,
 			if (!rm->peer_ref) {
 				if (source_ref) {
 					warning(_("multiple branches detected, incompatible with --set-upstream"));
-					goto skip;
+					goto cleanup;
 				} else {
 					source_ref = rm;
 				}
@@ -1658,7 +1671,7 @@ static int do_fetch(struct transport *transport,
 				warning(_("could not set upstream of HEAD to '%s' from '%s' when "
 					  "it does not point to any branch."),
 					shortname, transport->remote->name);
-				goto skip;
+				goto cleanup;
 			}
 
 			if (!strcmp(source_ref->name, "HEAD") ||
@@ -1678,21 +1691,9 @@ static int do_fetch(struct transport *transport,
 				  "you need to specify exactly one branch with the --set-upstream option"));
 		}
 	}
-skip:
-	free_refs(ref_map);
-
-	/* if neither --no-tags nor --tags was specified, do automated tag
-	 * following ... */
-	if (tags == TAGS_DEFAULT && autotags) {
-		struct ref **tail = &ref_map;
-		ref_map = NULL;
-		find_non_local_tags(remote_refs, &ref_map, &tail);
-		if (ref_map)
-			backfill_tags(transport, ref_map, worktrees);
-		free_refs(ref_map);
-	}
 
 cleanup:
+	free_refs(ref_map);
 	free_worktrees(worktrees);
 	return retcode;
 }