git-branch -D: make it work even when on a yet-to-be-born branch

diff --git a/tree-diff.c b/tree-diff.c
index 7e2f4f088a359fe138b085730ba1b3465342e9e9..37d235e06e2cbfbd761fd02d7e73648a14a60daf 100644 (file)
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -215,6 +215,24 @@ int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const cha
        return retval;
 }
 
+int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
+{
+       int retval;
+       void *tree;
+       struct tree_desc empty, real;
+
+       tree = read_object_with_reference(new, tree_type, &real.size, NULL);
+       if (!tree)
+               die("unable to read root tree (%s)", sha1_to_hex(new));
+       real.buf = tree;
+
+       empty.size = 0;
+       empty.buf = "";
+       retval = diff_tree(&empty, &real, base, opt);
+       free(tree);
+       return retval;
+}
+
 static int count_paths(const char **paths)
 {
        int i = 0;