[PATCH] branch: implement shortcut to delete last branch

[Aaron Greenberg <p@aaronjgreenberg.com>]

This patch gives git-branch the ability to delete the previous
checked-out branch using the "-" shortcut. This shortcut already exists
for git-checkout, git-merge, and git-revert. A common workflow is

1. Do some work on a local topic-branch and push it to a remote.
2. 'remote/topic-branch' gets merged in to 'remote/master'.
3. Switch back to local master and fetch 'remote/master'.
4. Delete previously checked-out local topic-branch.

$ git checkout -b topic-a
$ # Do some work...
$ git commit -am "Implement feature A"
$ git push origin topic-a

$ git checkout master
$ git branch -d topic-a
$ # With this patch, a user could simply type
$ git branch -d -

"-" is a useful shortcut for cleaning up a just-merged branch
(or a just switched-from branch.)

Signed-off-by: Aaron Greenberg <p@aaronjgreenberg.com>
---
 builtin/branch.c  | 3 +++
 t/t3200-branch.sh | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/builtin/branch.c b/builtin/branch.c
index 6d0cea9..9e37078 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -221,6 +221,9 @@ static int delete_branches(int argc, const char **argv, int force, int kinds,
 		char *target = NULL;
 		int flags = 0;
 
+		if (!strcmp(argv[i], "-"))
+			argv[i] = "@{-1}";
+
 		strbuf_branchname(&bname, argv[i], allowed_interpret);
 		free(name);
 		name = mkpathdup(fmt, bname.buf);
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index 6c0b7ea..78c25aa 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -776,6 +776,14 @@ test_expect_success 'deleting currently checked out branch fails' '
 	test_must_fail git branch -d my7
 '
 
+test_expect_success 'test deleting last branch' '
+	git checkout -b my7.1 &&
+	git checkout  - &&
+	test_path_is_file .git/refs/heads/my7.1 &&
+	git branch -d - &&
+	test_path_is_missing .git/refs/heads/my7.1
+'
+
 test_expect_success 'test --track without .fetch entries' '
 	git branch --track my8 &&
 	test "$(git config branch.my8.remote)" &&
-- 
2.7.4