[PATCH v2 2/5] help: correct usage & behavior of "git help --guides"

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

As noted in 65f98358c0c (builtin/help.c: add --guide option,
2013-04-02) and a133737b809 (doc: include --guide option description
for "git help", 2013-04-02) which introduced the --guide option it
cannot be combined with e.g. <command>.

Change both the usage string to reflect that, and test and assert for
this behavior in the command itself. Now that we assert this in code
we don't need to exhaustively describe the previous confusing behavior
in the documentation either, instead of silently ignoring the provided
argument we'll now error out.

The comment being removed was added in 15f7d494380 (builtin/help.c:
split "-a" processing into two, 2013-04-02). The "Ignore any remaining
args" part of it is now no longer applicable as explained above, let's
just remove it entirely, it's rather obvious that if we're returning
we're done.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-help.txt |  6 +++---
 builtin/help.c             | 11 +++++++----
 t/t0012-help.sh            |  4 ++++
 3 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-help.txt b/Documentation/git-help.txt
index 568a0b606f3..cb8e3d4da9e 100644
--- a/Documentation/git-help.txt
+++ b/Documentation/git-help.txt
@@ -8,8 +8,9 @@ git-help - Display help information about Git
 SYNOPSIS
 --------
 [verse]
-'git help' [-a|--all [--[no-]verbose]] [-g|--guides]
+'git help' [-a|--all [--[no-]verbose]]
 	   [[-i|--info] [-m|--man] [-w|--web]] [COMMAND|GUIDE]
+'git help' [-g|--guides]
 
 DESCRIPTION
 -----------
@@ -58,8 +59,7 @@ OPTIONS
 
 -g::
 --guides::
-	Prints a list of the Git concept guides on the standard output. This
-	option overrides any given command or guide name.
+	Prints a list of the Git concept guides on the standard output.
 
 -i::
 --info::
diff --git a/builtin/help.c b/builtin/help.c
index 44ea2798cda..51b18c291d8 100644
--- a/builtin/help.c
+++ b/builtin/help.c
@@ -59,8 +59,9 @@ static struct option builtin_help_options[] = {
 };
 
 static const char * const builtin_help_usage[] = {
-	N_("git help [-a|--all] [-g|--guides] [--[no-]verbose]]\n"
+	N_("git help [-a|--all] [--[no-]verbose]]\n"
 	   "         [[-i|--info] [-m|--man] [-w|--web]] [<command>]"),
+	N_("git help [-g|--guides]"),
 	NULL
 };
 
@@ -552,6 +553,11 @@ int cmd_help(int argc, const char **argv, const char *prefix)
 			builtin_help_usage, 0);
 	parsed_help_format = help_format;
 
+	/* Options that take no further arguments */
+	if (argc && show_guides)
+		usage_msg_opt(_("--guides cannot be combined with other options"),
+			      builtin_help_usage, builtin_help_options);
+
 	if (show_all) {
 		git_config(git_help_config, NULL);
 		if (verbose) {
@@ -582,9 +588,6 @@ int cmd_help(int argc, const char **argv, const char *prefix)
 
 	if (show_all || show_guides) {
 		printf("%s\n", _(git_more_info_string));
-		/*
-		* We're done. Ignore any remaining args
-		*/
 		return 0;
 	}
 
diff --git a/t/t0012-help.sh b/t/t0012-help.sh
index 5679e29c624..c3aa016fd30 100755
--- a/t/t0012-help.sh
+++ b/t/t0012-help.sh
@@ -34,6 +34,10 @@ test_expect_success 'basic help commands' '
 	git help -a >/dev/null
 '
 
+test_expect_success 'invalid usage' '
+	test_expect_code 129 git help -g git-add
+'
+
 test_expect_success "works for commands and guides by default" '
 	configure_help &&
 	git help status &&
-- 
2.33.0.873.g125ff7b9940