parse-options: introduce OPT_HIDDEN_GROUP

Hidden options are not shown by `git <cmd> -h`, but are still shown by
`git <cmd> --help-all`. If there are a lot of hidden options or if they
don't belong to the same categories as other options, there is
currently no way to properly group them.

Using `OPT_GROUP("Foo")` means that "Foo" will always be shown which we
don't want if that group contains only hidden options.

To provide a way to have groups shown only when hidden options are
shown, let's implement an OPT_HIDDEN_GROUP macro.

To test this new macro, let's also improve `test-tool parse-options`
and test its output with `--help-all`.

Signed-off-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

parse-options.c

@@ -1414,6 +1414,8 @@ static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t
 
 		if (opts->type == OPTION_SUBCOMMAND)
 			continue;
+		if (!full && (opts->flags & PARSE_OPT_HIDDEN))
+			continue;
 		if (opts->type == OPTION_GROUP) {
 			fputc('\n', outfile);
 			need_newline = 0;
@@ -1421,8 +1423,6 @@ static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t
 				fprintf(outfile, "%s\n", _(opts->help));
 			continue;
 		}
-		if (!full && (opts->flags & PARSE_OPT_HIDDEN))
-			continue;
 
 		if (need_newline) {
 			fputc('\n', outfile);

parse-options.h

@@ -237,6 +237,11 @@ struct option {
 	.type = OPTION_GROUP, \
 	.help = (h), \
 }
+#define OPT_HIDDEN_GROUP(h) { \
+	.type = OPTION_GROUP, \
+	.help = (h), \
+	.flags = PARSE_OPT_HIDDEN, \
+}
 #define OPT_BIT(s, l, v, h, b)      OPT_BIT_F(s, l, v, h, b, 0)
 #define OPT_BITOP(s, l, v, h, set, clear) { \
 	.type = OPTION_BITOP, \

t/helper/test-parse-options.c

@@ -209,6 +209,10 @@ int cmd__parse_options(int argc, const char **argv)
 		OPT_GROUP("Alias"),
 		OPT_STRING('A', "alias-source", &string, "string", "get a string"),
 		OPT_ALIAS('Z', "alias-target", "alias-source"),
+		OPT_HIDDEN_GROUP("Hidden options"),
+		OPT_HIDDEN_BOOL(0, "hidden-bool", &boolean, "get a boolean"),
+		OPT_INTEGER_F('k', "hidden-integer", &integer, "get a integer",
+			      PARSE_OPT_HIDDEN),
 		OPT_END(),
 	};
 	int ret = 0;

t/t0040-parse-options.sh

@@ -7,7 +7,7 @@ test_description='our own option parser'
 
 . ./test-lib.sh
 
-cat >expect <<\EOF
+cat >expect-part1 <<\EOF
 usage: test-tool parse-options <options>
 
     A helper function for the parse-options API.
@@ -41,6 +41,9 @@ String options
     --[no-]string2 <str>  get another string
     --[no-]st <st>        get another string (pervert ordering)
     -o <str>              get another string
+EOF
+
+cat >expect-part2 <<\EOF
     --longhelp            help text of this entry
                           spans multiple lines
     --[no-]list <str>     add str to list
@@ -67,12 +70,32 @@ Alias
 
 EOF
 
+cat >expect-noop <<\EOF
+    --[no-]obsolete       no-op (backward compatibility)
+EOF
+
+cat >expect-hidden <<\EOF
+Hidden options
+    --[no-]hidden-bool    get a boolean
+    -k, --[no-]hidden-integer <n>
+                          get a integer
+
+EOF
+
 test_expect_success 'test help' '
+	cat expect-part1 expect-part2 >expect &&
 	test-tool parse-options -h >output 2>output.err &&
 	test_must_be_empty output.err &&
 	test_cmp expect output
 '
 
+test_expect_success 'test --help-all shows hidden group and options' '
+	cat expect-part1 expect-noop expect-part2 expect-hidden >expect-help-all &&
+	test-tool parse-options --help-all >output 2>output.err &&
+	test_must_be_empty output.err &&
+	test_cmp expect-help-all output
+'
+
 mv expect expect.err
 
 check () {