[v2 PATCH 1/2] reset: add '-' shorthand for '@{-1}'

[Sundararajan R <dyoucme@gmail.com>]

Teaching reset the - shorthand involves checking if any file named '-' exists 
because it then becomes ambiguous as to whether the user wants to reset the
file '-' or if he wants to reset the working tree to the previous branch.

check_filename() is used to perform this check. A similar ambiguity occurs 
when the file @{-1} exits. Therefore, when the files '-' or '@{-1}' exist 
then the program dies with a message about the ambiguous argument.

Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Sundararajan R <dyoucme@gmail.com>
---
Have made the modifications suggest by you, Eric.
Removed the part where the user is told that he can use ./- instead.

 builtin/reset.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/builtin/reset.c b/builtin/reset.c
index 4c08ddc..88ce0c5 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -192,6 +192,7 @@ static void parse_args(struct pathspec *pathspec,
 {
 	const char *rev = "HEAD";
 	unsigned char unused[20];
+	int file_named_minus = 0;
 	/*
 	 * Possible arguments are:
 	 *
@@ -205,6 +206,12 @@ static void parse_args(struct pathspec *pathspec,
 	 */
 
 	if (argv[0]) {
+		if (!strcmp(argv[0], "-") && !argv[1]) {
+			if (!check_filename(prefix, "-"))
+				argv[0] = "@{-1}";
+			else
+				file_named_minus = 1;
+		}
 		if (!strcmp(argv[0], "--")) {
 			argv++; /* reset to HEAD, possibly with paths */
 		} else if (argv[1] && !strcmp(argv[1], "--")) {
@@ -226,7 +233,13 @@ static void parse_args(struct pathspec *pathspec,
 			rev = *argv++;
 		} else {
 			/* Otherwise we treat this as a filename */
-			verify_filename(prefix, argv[0], 1);
+			if (file_named_minus) {
+				die(_("ambiguous argument '-': both revision and filename\n"
+					"Use '--' to separate paths from revisions, like this:\n"
+					"'git <command> [<revision>...] -- [<file>...]'"));
+			}
+			else
+				verify_filename(prefix, argv[0], 1);
 		}
 	}
 	*rev_ret = rev;
-- 
2.1.0