[PATCH 6/7] stage: add 'diff' subcommand

[Felipe Contreras <felipe.contreras@gmail.com>]

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
---
 Documentation/git-stage.txt | 5 +++++
 builtin/stage.c             | 6 +++++-
 t/t3710-stage.sh            | 7 +++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Documentation/git-stage.txt b/Documentation/git-stage.txt
index e2f83783b2..460a8d6228 100644
--- a/Documentation/git-stage.txt
+++ b/Documentation/git-stage.txt
@@ -12,6 +12,7 @@ SYNOPSIS
 'git stage' [options] [--] [<paths>...]
 'git stage' (-a | --add) [options] [--] [<paths>...]
 'git stage' (-r | --remove) [options] [--] [<paths>...]
+'git stage' (-d | --diff) [options] [--] [<paths>...]
 
 
 DESCRIPTION
@@ -32,11 +33,15 @@ OPTIONS
 --remove::
 	Remove changes from the staging area. See linkgit:git-reset[1].
 
+-d::
+--diff::
+	View the changes staged for the next commit. See linkgit:git-diff[1].
 
 SEE ALSO
 --------
 linkgit:git-add[1]
 linkgit:git-reset[1]
+linkgit:git-diff[1]
 
 GIT
 ---
diff --git a/builtin/stage.c b/builtin/stage.c
index 2d50b3c393..c57bb2d683 100644
--- a/builtin/stage.c
+++ b/builtin/stage.c
@@ -10,6 +10,7 @@ static const char *const stage_usage[] = {
 	N_("git stage [options] [--] <paths>..."),
 	N_("git stage --add [options] [--] <paths>..."),
 	N_("git stage --remove [options] [--] <paths>..."),
+	N_("git stage --diff [options] [<commit>] [--] <paths>..."),
 	NULL
 };
 
@@ -41,11 +42,12 @@ static int rerun(int argc, const char **argv, ...)
 
 int cmd_stage(int argc, const char **argv, const char *prefix)
 {
-	int add = 0, remove = 0;
+	int add = 0, remove = 0, diff = 0;
 
 	struct option options[] = {
 		OPT_BOOL_F('a', "add", &add, N_("add changes"), PARSE_OPT_NONEG),
 		OPT_BOOL_F('r', "remove", &remove, N_("remove changes"), PARSE_OPT_NONEG),
+		OPT_BOOL_F('d', "diff", &diff, N_("show changes"), PARSE_OPT_NONEG),
 		OPT_END()
 	};
 
@@ -54,6 +56,8 @@ int cmd_stage(int argc, const char **argv, const char *prefix)
 
 	if (remove)
 		return rerun(argc, argv, "reset", NULL);
+	if (diff)
+		return rerun(argc, argv, "diff", "--staged", NULL);
 
 	return rerun(argc, argv, "add", NULL);
 }
diff --git a/t/t3710-stage.sh b/t/t3710-stage.sh
index 834eee66d5..aab979c20c 100755
--- a/t/t3710-stage.sh
+++ b/t/t3710-stage.sh
@@ -35,4 +35,11 @@ test_expect_success 'unstage' '
 	! in_stage bar
 '
 
+test_expect_success 'diff' '
+	echo foo > foo &&
+	git stage --add foo &&
+	git stage --diff > out &&
+	test_file_not_empty out
+'
+
 test_done
-- 
2.32.0.48.g096519100f