[PATCH] help: make option --help open man pages only for Git commands

[Ralf Thielow <ralf.thielow@gmail.com>]

If option --help is passed to a Git command, we try to open
the man page of that command. However, we do it even for commands
we don't know.  Make sure the command is known to Git before try
to open the man page.  If we don't know the command, give the
usual advice.

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
---
 builtin/help.c  | 21 ++++++++++++++-------
 t/t0012-help.sh | 15 +++++++++++++++
 2 files changed, 29 insertions(+), 7 deletions(-)
 create mode 100755 t/t0012-help.sh

diff --git a/builtin/help.c b/builtin/help.c
index 8848013..55d45de 100644
--- a/builtin/help.c
+++ b/builtin/help.c
@@ -433,10 +433,22 @@ static void list_common_guides_help(void)
 	putchar('\n');
 }
 
+static void check_git_cmd(const char* cmd) {
+	char *alias = alias_lookup(cmd);
+
+	if (!is_git_command(cmd)) {
+		if (alias) {
+			printf_ln(_("`git %s' is aliased to `%s'"), cmd, alias);
+			free(alias);
+			exit(0);
+		} else
+			help_unknown_cmd(cmd);
+	}
+}
+
 int cmd_help(int argc, const char **argv, const char *prefix)
 {
 	int nongit;
-	char *alias;
 	enum help_format parsed_help_format;
 
 	argc = parse_options(argc, argv, prefix, builtin_help_options,
@@ -476,12 +488,7 @@ int cmd_help(int argc, const char **argv, const char *prefix)
 	if (help_format == HELP_FORMAT_NONE)
 		help_format = parse_help_format(DEFAULT_HELP_FORMAT);
 
-	alias = alias_lookup(argv[0]);
-	if (alias && !is_git_command(argv[0])) {
-		printf_ln(_("`git %s' is aliased to `%s'"), argv[0], alias);
-		free(alias);
-		return 0;
-	}
+	check_git_cmd(argv[0]);
 
 	switch (help_format) {
 	case HELP_FORMAT_NONE:
diff --git a/t/t0012-help.sh b/t/t0012-help.sh
new file mode 100755
index 0000000..0dab88d
--- /dev/null
+++ b/t/t0012-help.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+
+test_description='help'
+
+. ./test-lib.sh
+
+test_expect_success "pass --help to unknown command" "
+	cat <<-EOF >expected &&
+		git: '123' is not a git command. See 'git --help'.
+	EOF
+	(git 123 --help 2>actual || true) &&
+	test_i18ncmp expected actual
+"
+
+test_done
-- 
2.9.2.911.g31804cd.dirty