remote set-head: better output for --auto

Currently, set-head --auto will print a message saying "remote/HEAD set
to branch", which implies something was changed.

Change the output of --auto, so the output actually reflects what was
done: a) set a previously unset HEAD, b) change HEAD because remote
changed or c) no updates. As edge cases, if HEAD is changed from
a previous symbolic reference that was not a remote branch, explicitly
call attention to this fact, and also notify the user if the previous
reference was not a symbolic reference.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 47 insertions, 12 deletions

diff --git a/builtin/remote.c b/builtin/remote.c
index bcc3ee91ef..6d659d63ca 100644
--- a/builtin/remote.c
+++ b/builtin/remote.c
@@ -1399,10 +1399,38 @@ static int show(int argc, const char **argv, const char *prefix)
 	return result;
 }
 
+static void report_set_head_auto(const char *remote, const char *head_name,
+			struct strbuf *b_local_head, int was_detached) {
+	struct strbuf buf_prefix = STRBUF_INIT;
+	const char *prev_head = NULL;
+
+	strbuf_addf(&buf_prefix, "refs/remotes/%s/", remote);
+	skip_prefix(b_local_head->buf, buf_prefix.buf, &prev_head);
+
+	if (prev_head && !strcmp(prev_head, head_name))
+		printf(_("'%s/HEAD' is unchanged and points to '%s'\n"),
+			remote, head_name);
+	else if (prev_head)
+		printf(_("'%s/HEAD' has changed from '%s' and now points to '%s'\n"),
+			remote, prev_head, head_name);
+	else if (!b_local_head->len)
+		printf(_("'%s/HEAD' is now created and points to '%s'\n"),
+			remote, head_name);
+	else if (was_detached && b_local_head->len)
+		printf(_("'%s/HEAD' was detached at '%s' and now points to '%s'\n"),
+			remote, b_local_head->buf, head_name);
+	else
+		printf(_("'%s/HEAD' used to point to '%s' "
+			"(which is not a remote branch), but now points to '%s'\n"),
+			remote, b_local_head->buf, head_name);
+	strbuf_release(&buf_prefix);
+}
+
 static int set_head(int argc, const char **argv, const char *prefix)
 {
-	int i, opt_a = 0, opt_d = 0, result = 0;
-	struct strbuf b_head = STRBUF_INIT, b_remote_head = STRBUF_INIT;
+	int i, opt_a = 0, opt_d = 0, result = 0, was_detached;
+	struct strbuf b_head = STRBUF_INIT, b_remote_head = STRBUF_INIT,
+		b_local_head = STRBUF_INIT;
 	char *head_name = NULL;
 	struct ref_store *refs = get_main_ref_store(the_repository);
 
@@ -1440,20 +1468,27 @@ static int set_head(int argc, const char **argv, const char *prefix)
 	} else
 		usage_with_options(builtin_remote_sethead_usage, options);
 
-	if (head_name) {
-		strbuf_addf(&b_remote_head, "refs/remotes/%s/%s", argv[0], head_name);
-		/* make sure it's valid */
-		if (!refs_ref_exists(refs, b_remote_head.buf))
-			result |= error(_("Not a valid ref: %s"), b_remote_head.buf);
-		else if (refs_update_symref(refs, b_head.buf, b_remote_head.buf, "remote set-head"))
-			result |= error(_("Could not set up %s"), b_head.buf);
-		else if (opt_a)
-			printf("%s/HEAD set to %s\n", argv[0], head_name);
-		free(head_name);
+	if (!head_name)
+		goto cleanup;
+	strbuf_addf(&b_remote_head, "refs/remotes/%s/%s", argv[0], head_name);
+	if (!refs_ref_exists(refs, b_remote_head.buf)) {
+		result |= error(_("Not a valid ref: %s"), b_remote_head.buf);
+		goto cleanup;
+	}
+	was_detached = refs_update_symref_extended(refs, b_head.buf, b_remote_head.buf,
+			"remote set-head", &b_local_head);
+	if (was_detached == -1) {
+		result |= error(_("Could not set up %s"), b_head.buf);
+		goto cleanup;
 	}
+	if (opt_a)
+		report_set_head_auto(argv[0], head_name, &b_local_head, was_detached);
 
+cleanup:
+	free(head_name);
 	strbuf_release(&b_head);
 	strbuf_release(&b_remote_head);
+	strbuf_release(&b_local_head);
 	return result;
 }