builtin/am: introduce write_state_*() helper functions

diff --git a/builtin/worktree.c b/builtin/worktree.c
index 25fe25b45f7771bb3b000ae92aa5f24875adc51e..6a264ee749221cd6c6bf98ce68790bdec3dd82c5 100644 (file)
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -5,6 +5,7 @@
 #include "argv-array.h"
 #include "run-command.h"
 #include "sigchain.h"
+#include "refs.h"
 
 static const char * const worktree_usage[] = {
        N_("git worktree add [<options>] <path> <branch>"),
@@ -289,11 +290,17 @@ static int add(int ac, const char **av, const char *prefix)
        ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
        if (new_branch && new_branch_force)
                die(_("-b and -B are mutually exclusive"));
-       if (ac != 2)
+       if (ac < 1 || ac > 2)
                usage_with_options(worktree_usage, options);
 
        path = prefix ? prefix_filename(prefix, strlen(prefix), av[0]) : av[0];
-       branch = av[1];
+       branch = ac < 2 ? "HEAD" : av[1];
+
+       if (ac < 2 && !new_branch && !new_branch_force) {
+               int n;
+               const char *s = worktree_basename(path, &n);
+               new_branch = xstrndup(s, n);
+       }
 
        argv_array_push(&cmd, "checkout");
        if (force)