builtin/maintenance: mark "--task=" and "--schedule=" as incompatible

The "--task=" option explicitly allows the user to say which maintenance
tasks should be run, whereas "--schedule=" only respects the maintenance
strategy configured for a specific repository. As such, it is not
sensible to accept both options at the same time.

Mark them as incompatible with one another. While at it, also convert
the existing logic that marks "--auto" and "--schedule=" as incompatible
to use `die_for_incompatible_opt2()`.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

builtin/gc.c

@@ -1785,8 +1785,10 @@ static int maintenance_run(int argc, const char **argv, const char *prefix,
 			     builtin_maintenance_run_usage,
 			     PARSE_OPT_STOP_AT_NON_OPTION);
 
-	if (opts.auto_flag && opts.schedule)
-		die(_("use at most one of --auto and --schedule=<frequency>"));
+	die_for_incompatible_opt2(opts.auto_flag, "--auto",
+				  opts.schedule, "--schedule=");
+	die_for_incompatible_opt2(selected_tasks.nr, "--task=",
+				  opts.schedule, "--schedule=");
 
 	gc_config(&cfg);
 	initialize_task_config(&selected_tasks, opts.schedule);

t/t7900-maintenance.sh

@@ -610,7 +610,12 @@ test_expect_success 'rerere-gc task with --auto honors maintenance.rerere-gc.aut
 
 test_expect_success '--auto and --schedule incompatible' '
 	test_must_fail git maintenance run --auto --schedule=daily 2>err &&
-	test_grep "at most one" err
+	test_grep "cannot be used together" err
+'
+
+test_expect_success '--task and --schedule incompatible' '
+	test_must_fail git maintenance run --task=pack-refs --schedule=daily 2>err &&
+	test_grep "cannot be used together" err
 '
 
 test_expect_success 'invalid --schedule value' '