builtin: also setup gently for --help-all

Git experts often check the help summary of a command to make sure they
spell options right when suggesting advice to colleagues. Further, they
might check hidden options when responding to queries about deprecated
options like git-rebase(1)'s "preserve merges" option. But some commands
don't support "--help-all" outside of a git directory. Running (for
example)

    git rebase --help-all

outside a directory fails in "setup_git_directory", erroring with the
localized form of

    fatal: not a git repository (or any of the parent directories): .git

Like 99caeed05d (Let 'git <command> -h' show usage without a git dir,
2009-11-09), we want to show the "--help-all" output even without a git
dir. Make "--help-all" where we expect "-h" to mean
"setup_git_directory_gently", and interpose early in the natural place
("show_usage_with_options_if_asked").

Do the same for usage callers with show_usage_if_asked.

The exception is merge-recursive, whose help block doesn't use newer
APIs.

Best-viewed-with: --ignore-space-change
Signed-off-by: D. Ben Knoble <ben.knoble+github@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/merge-recursive.c

@@ -38,7 +38,8 @@ int cmd_merge_recursive(int argc,
 	if (argv[0] && ends_with(argv[0], "-subtree"))
 		o.subtree_shift = "";
 
-	if (argc == 2 && !strcmp(argv[1], "-h")) {
+	if (argc == 2 && (!strcmp(argv[1], "-h") ||
+			  !strcmp(argv[1], "--help-all"))) {
 		struct strbuf msg = STRBUF_INIT;
 		strbuf_addf(&msg, builtin_merge_recursive_usage, argv[0]);
 		show_usage_if_asked(argc, argv, msg.buf);

git.c

@@ -445,7 +445,7 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv, struct
 	const char *prefix;
 	int run_setup = (p->option & (RUN_SETUP | RUN_SETUP_GENTLY));
 
-	help = argc == 2 && !strcmp(argv[1], "-h");
+	help = argc == 2 && (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help-all"));
 	if (help && (run_setup & RUN_SETUP))
 		/* demote to GENTLY to allow 'git cmd -h' outside repo */
 		run_setup = RUN_SETUP_GENTLY;

parse-options.c

@@ -1461,10 +1461,16 @@ void show_usage_with_options_if_asked(int ac, const char **av,
 				      const char * const *usagestr,
 				      const struct option *opts)
 {
-	if (ac == 2 && !strcmp(av[1], "-h")) {
+	if (ac == 2) {
+		if (!strcmp(av[1], "-h")) {
 			usage_with_options_internal(NULL, usagestr, opts,
 						    USAGE_NORMAL, USAGE_TO_STDOUT);
 			exit(129);
+		} else if (!strcmp(av[1], "--help-all")) {
+			usage_with_options_internal(NULL, usagestr, opts,
+						    USAGE_FULL, USAGE_TO_STDOUT);
+			exit(129);
+		}
 	}
 }
 

t/t1517-outside-repo.sh

@@ -133,6 +133,10 @@ do
 		test_expect_code 129 nongit git $cmd -h >usage &&
 		test_grep "[Uu]sage: git $cmd " usage
 	'
+	test_$expect_outcome $prereq "'git $cmd --help-all' outside a repository" '
+		test_expect_code 129 nongit git $cmd --help-all >usage &&
+		test_grep "[Uu]sage: git $cmd " usage
+	'
 done
 
 test_done

usage.c

@@ -192,7 +192,8 @@ static void show_usage_if_asked_helper(const char *err, ...)
 
 void show_usage_if_asked(int ac, const char **av, const char *err)
 {
-	if (ac == 2 && !strcmp(av[1], "-h"))
+	if (ac == 2 && (!strcmp(av[1], "-h") ||
+			!strcmp(av[1], "--help-all")))
 		show_usage_if_asked_helper(err);
 }