[PATCH v2 3/3] 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 for both commands
and concepts.  Make sure it is an actual command.

This makes "git <concept> --help" not working anymore, while
"git help <concept>" still works.

Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
---
 Documentation/git-help.txt |  5 +++--
 git.c                      | 15 ++++++++++++++-
 t/t0012-help.sh            |  8 ++++++++
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-help.txt b/Documentation/git-help.txt
index eeb1950..8d21e9f 100644
--- a/Documentation/git-help.txt
+++ b/Documentation/git-help.txt
@@ -29,8 +29,9 @@ guide is brought up. The 'man' program is used by default for this
 purpose, but this can be overridden by other options or configuration
 variables.
 
-Note that `git --help ...` is identical to `git help ...` because the
-former is internally converted into the latter.
+Note that `git --help ...` is almost identical to `git help ...` because
+the former is internally converted into the latter with option --exclude-guides
+being added.
 
 To display the linkgit:git[1] man page, use `git help git`.
 
diff --git a/git.c b/git.c
index 0f1937f..1c61151 100644
--- a/git.c
+++ b/git.c
@@ -522,21 +522,34 @@ static void strip_extension(const char **argv)
 
 static void handle_builtin(int argc, const char **argv)
 {
+	struct argv_array args = ARGV_ARRAY_INIT;
 	const char *cmd;
 	struct cmd_struct *builtin;
 
 	strip_extension(argv);
 	cmd = argv[0];
 
-	/* Turn "git cmd --help" into "git help cmd" */
+	/* Turn "git cmd --help" into "git help --exclude-guides cmd" */
 	if (argc > 1 && !strcmp(argv[1], "--help")) {
+		int i;
+
 		argv[1] = argv[0];
 		argv[0] = cmd = "help";
+
+		for (i = 0; i < argc; i++) {
+			argv_array_push(&args, argv[i]);
+			if (!i)
+				argv_array_push(&args, "--exclude-guides");
+		}
+
+		argc++;
+		argv = args.argv;
 	}
 
 	builtin = get_builtin(cmd);
 	if (builtin)
 		exit(run_builtin(builtin, argc, argv));
+	argv_array_clear(&args);
 }
 
 static void execv_dashed_external(const char **argv)
diff --git a/t/t0012-help.sh b/t/t0012-help.sh
index fb1abd7..2b90947 100755
--- a/t/t0012-help.sh
+++ b/t/t0012-help.sh
@@ -30,4 +30,12 @@ test_expect_success "--exclude-guides does not work for guides" "
 	test_i18ncmp expected actual
 "
 
+test_expect_success "--help does not work for guides" "
+	cat <<-EOF >expected &&
+		git: 'revisions' is not a git command. See 'git --help'.
+	EOF
+	test_must_fail git revisions --help 2>actual &&
+	test_i18ncmp expected actual
+"
+
 test_done
-- 
2.9.2.912.gd0c0e83