builtin rebase: optionally auto-detect the upstream

The `git rebase` command, when called without the `<upstream>`
command-line argument, automatically looks for the upstream
branch configured for the current branch.

With this commit, the builtin rebase learned that trick, too.

Signed-off-by: Pratik Karki <predatoramigo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/rebase.c b/builtin/rebase.c
index b2cf779f1b42a5623d7d376b4fcc0e9bcea28e97..7e2f68eb2822543964193af9a83f13bf9ad5ecd2 100644 (file)
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -622,6 +622,36 @@ static int parse_opt_interactive(const struct option *opt, const char *arg,
        return 0;
 }
 
+static void NORETURN error_on_missing_default_upstream(void)
+{
+       struct branch *current_branch = branch_get(NULL);
+
+       printf(_("%s\n"
+                "Please specify which branch you want to rebase against.\n"
+                "See git-rebase(1) for details.\n"
+                "\n"
+                "    git rebase '<branch>'\n"
+                "\n"),
+               current_branch ? _("There is no tracking information for "
+                       "the current branch.") :
+                       _("You are not currently on a branch."));
+
+       if (current_branch) {
+               const char *remote = current_branch->remote_name;
+
+               if (!remote)
+                       remote = _("<remote>");
+
+               printf(_("If you wish to set tracking information for this "
+                        "branch you can do so with:\n"
+                        "\n"
+                        "    git branch --set-upstream-to=%s/<branch> %s\n"
+                        "\n"),
+                      remote, current_branch->name);
+       }
+       exit(1);
+}
+
 int cmd_rebase(int argc, const char **argv, const char *prefix)
 {
        struct rebase_options options = {
@@ -1057,9 +1087,17 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
        }
 
        if (!options.root) {
-               if (argc < 1)
-                       die("TODO: handle @{upstream}");
-               else {
+               if (argc < 1) {
+                       struct branch *branch;
+
+                       branch = branch_get(NULL);
+                       options.upstream_name = branch_get_upstream(branch,
+                                                                   NULL);
+                       if (!options.upstream_name)
+                               error_on_missing_default_upstream();
+                       if (fork_point < 0)
+                               fork_point = 1;
+               } else {
                        options.upstream_name = argv[0];
                        argc--;
                        argv++;