revision arguments: ..B means HEAD..B, just like A.. means A..HEAD

For consistency reasons, we should probably allow that to be written as
just "..branch", the same way we can write "branch.." to mean "everything
in HEAD but not in "branch".

Signed-off-by: Junio C Hamano <junkio@cox.net>

2 files changed, 18 insertions, 12 deletions

diff --git a/rev-parse.c b/rev-parse.c
index f176c56f7f..e956cd5ed5 100644
--- a/rev-parse.c
+++ b/rev-parse.c
@@ -315,16 +315,17 @@ int main(int argc, char **argv)
 		dotdot = strstr(arg, "..");
 		if (dotdot) {
 			unsigned char end[20];
-			char *n = dotdot+2;
+			char *next = dotdot + 2;
+			char *this = arg;
 			*dotdot = 0;
-			if (!get_sha1(arg, sha1)) {
-				if (!*n)
-					n = "HEAD";
-				if (!get_sha1(n, end)) {
-					show_rev(NORMAL, end, n);
-					show_rev(REVERSED, sha1, arg);
-					continue;
-				}
+			if (!*next)
+				next = "HEAD";
+			if (dotdot == arg)
+				this = "HEAD";
+			if (!get_sha1(this, sha1) && !get_sha1(next, end)) {
+				show_rev(NORMAL, end, next);
+				show_rev(REVERSED, sha1, this);
+				continue;
 			}
 			*dotdot = '.';
 		}
diff --git a/revision.c b/revision.c
index 745b0d2e10..2cda7e0edc 100644
--- a/revision.c
+++ b/revision.c
@@ -642,14 +642,19 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 		if (dotdot) {
 			unsigned char from_sha1[20];
 			char *next = dotdot + 2;
+			char *this = arg;
+			static const char HEAD[] = "HEAD";
 			*dotdot = 0;
 			if (!*next)
-				next = "HEAD";
-			if (!get_sha1(arg, from_sha1) && !get_sha1(next, sha1)) {
+				next = HEAD;
+			if (dotdot == arg)
+				this = HEAD;
+			if (!get_sha1(this, from_sha1) &&
+			    !get_sha1(next, sha1)) {
 				struct commit *exclude;
 				struct commit *include;
 
-				exclude = get_commit_reference(revs, arg, from_sha1, flags ^ UNINTERESTING);
+				exclude = get_commit_reference(revs, this, from_sha1, flags ^ UNINTERESTING);
 				include = get_commit_reference(revs, next, sha1, flags);
 				if (!exclude || !include)
 					die("Invalid revision range %s..%s", arg, next);