[PATCH v3 1/2] reset: enable '-' short-hand for previous branch

[Sudhanshu Shekhar <sudshekhar02@gmail.com>]

git reset -' will reset to the previous branch. It will behave similar
to @{-1} except when a file named '@{-1}' is present. To refer to a file
named '-', use ./- or the -- flag.

Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>
Signed-off-by: Sudhanshu Shekhar <sudshekhar02@gmail.com>
---
Eric, I have added a user_input variable to record the input entered by the user. This way I can avoid the multiple 'if' clauses. Thank you for the suggestion.
I have also removed the unrelated change that I had unintentionally committed. I am sending this patch on the thread for further review. Once both the patches are reviewed and accepted, I will create a new mail for it. Hope that is okay.

Regards,
Sudhanshu

 builtin/reset.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/builtin/reset.c b/builtin/reset.c
index 4c08ddc..b428241 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -192,6 +192,8 @@ static void parse_args(struct pathspec *pathspec,
 {
 	const char *rev = "HEAD";
 	unsigned char unused[20];
+	int substituted_minus = 0;
+	char *user_input = argv[0];
 	/*
 	 * Possible arguments are:
 	 *
@@ -205,6 +207,10 @@ static void parse_args(struct pathspec *pathspec,
 	 */
 
 	if (argv[0]) {
+		if (!strcmp(argv[0], "-")) {
+			argv[0] = "@{-1}";
+			substituted_minus = 1;
+		}
 		if (!strcmp(argv[0], "--")) {
 			argv++; /* reset to HEAD, possibly with paths */
 		} else if (argv[1] && !strcmp(argv[1], "--")) {
@@ -222,9 +228,12 @@ static void parse_args(struct pathspec *pathspec,
 			 * Ok, argv[0] looks like a commit/tree; it should not
 			 * be a filename.
 			 */
-			verify_non_filename(prefix, argv[0]);
+			verify_non_filename(prefix, user_input);
 			rev = *argv++;
 		} else {
+			/* We were treating "-" as a commit and not a file */
+			if (substituted_minus)
+				argv[0] = "-";
 			/* Otherwise we treat this as a filename */
 			verify_filename(prefix, argv[0], 1);
 		}
-- 
2.3.1.278.ge5c7b1f.dirty