[PATCH v2 1/4] parse-options: fix completion format when first option is skipped

[Patrick Steinhardt <ps@pks.im>]

The "--git-completion-helper" option can be passed to any command or
subcommand that uses the parse-options interface. The output it
generates is a space-separated list of subcommands or options understood
by the command.

The format is slightly broken though in the case where the first option
is not being printed, like for example a group or a hidden option. In
that case, `show_gitcomp()` will of course skip that first entry. But
when printing the next option it checks for `opts == original_opts` to
verify whether we're printing the first option. The check will evaluate
to false though as we have skipped it, and thus we'll print a leading
space even though we have printed nothing else yet.

Fix that bug by tracking whether we have already printed anything via a
local variable.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 parse-options.c               | 4 +++-
 t/helper/test-parse-options.c | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/parse-options.c b/parse-options.c
index 4519ead9dc..8bb30ec116 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -845,6 +845,7 @@ static int show_gitcomp(const struct option *opts, int show_all)
 {
 	const struct option *original_opts = opts;
 	int nr_noopts = 0;
+	bool shown = false;
 
 	for (; opts->type != OPTION_END; opts++) {
 		const char *prefix = "--";
@@ -882,8 +883,9 @@ static int show_gitcomp(const struct option *opts, int show_all)
 			suffix = "=";
 		if (starts_with(opts->long_name, "no-"))
 			nr_noopts++;
-		printf("%s%s%s%s", opts == original_opts ? "" : " ",
+		printf("%s%s%s%s", shown ? " " : "",
 		       prefix, opts->long_name, suffix);
+		shown = true;
 	}
 	show_negated_gitcomp(original_opts, show_all, -1);
 	show_negated_gitcomp(original_opts, show_all, nr_noopts);
diff --git a/t/helper/test-parse-options.c b/t/helper/test-parse-options.c
index f181f0c02d..fbafd67756 100644
--- a/t/helper/test-parse-options.c
+++ b/t/helper/test-parse-options.c
@@ -351,6 +351,7 @@ static int parse_subcommand__cmd(int argc, const char **argv,
 	parse_opt_subcommand_fn *fn = NULL;
 	int opt = 0;
 	struct option options[] = {
+		OPT_GROUP("Subcommands"),
 		OPT_SUBCOMMAND("subcmd-one", &fn, subcmd_one),
 		OPT_SUBCOMMAND("subcmd-two", &fn, subcmd_two),
 		OPT_INTEGER('o', "opt", &opt, "an integer option"),

-- 
2.56.0.353.g0856645cf6.dirty