branch,checkout: fix --track usage strings

As Ævar pointed out in [1], the use of PARSE_OPT_LITERAL_ARGHELP with a
list of allowed parameters is not recommended. Both git-branch and
git-checkout were changed in d311566 (branch: add flags and config to
inherit tracking, 2021-12-20) to use this discouraged combination for
their --track flags.

Fix this by removing PARSE_OPT_LITERAL_ARGHELP, and changing the arghelp
to simply be "mode". Users may discover allowed values in the manual
pages.

[1]: https://lore.kernel.org/git/[email protected]/

Signed-off-by: Josh Steadmon <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: steadmon

builtin/branch.c

@@ -632,9 +632,9 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		OPT__VERBOSE(&filter.verbose,
 			N_("show hash and subject, give twice for upstream branch")),
 		OPT__QUIET(&quiet, N_("suppress informational messages")),
-		OPT_CALLBACK_F('t', "track",  &track, "direct|inherit",
+		OPT_CALLBACK_F('t', "track",  &track, N_("mode"),
 			N_("set branch tracking configuration"),
-			PARSE_OPT_OPTARG | PARSE_OPT_LITERAL_ARGHELP,
+			PARSE_OPT_OPTARG,
 			parse_opt_tracking_mode),
 		OPT_SET_INT_F(0, "set-upstream", &track, N_("do not use"),
 			BRANCH_TRACK_OVERRIDE, PARSE_OPT_HIDDEN),

builtin/checkout.c

@@ -1530,9 +1530,9 @@ static struct option *add_common_switch_branch_options(
 {
 	struct option options[] = {
 		OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
-		OPT_CALLBACK_F('t', "track",  &opts->track, "direct|inherit",
-			N_("set up tracking mode (see git-pull(1))"),
-			PARSE_OPT_OPTARG | PARSE_OPT_LITERAL_ARGHELP,
+		OPT_CALLBACK_F('t', "track",  &opts->track, N_("mode"),
+			N_("set branch tracking configuration"),
+			PARSE_OPT_OPTARG,
 			parse_opt_tracking_mode),
 		OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
 			   PARSE_OPT_NOCOMPLETE),