builtin rebase: support `git rebase <upstream> <switch-to>`

This commit adds support for `switch-to` which is used to switch to the
target branch if needed. The equivalent codes found in shell script
`git-legacy-rebase.sh` is converted to builtin `rebase.c`.

Signed-off-by: Pratik Karki <predatoramigo@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/rebase.c b/builtin/rebase.c
index afc75fe7314e6d23f4c9c36138eede77064d804c..e817956d96fe50bce975a1c87fd8f8df132e53ea 100644 (file)
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -79,6 +79,7 @@ struct rebase_options {
        struct commit *onto;
        const char *onto_name;
        const char *revisions;
        struct commit *onto;
        const char *onto_name;
        const char *revisions;

+       const char *switch_to;

        int root;
        struct commit *restrict_revision;
        int dont_finish_rebase;
        int root;
        struct commit *restrict_revision;
        int dont_finish_rebase;


@@ -186,6 +187,8 @@ static int run_specific_rebase(struct rebase_options *opts)
                opts->flags & REBASE_DIFFSTAT ? "t" : "");
        add_var(&script_snippet, "force_rebase",
                opts->flags & REBASE_FORCE ? "t" : "");
                opts->flags & REBASE_DIFFSTAT ? "t" : "");
        add_var(&script_snippet, "force_rebase",
                opts->flags & REBASE_FORCE ? "t" : "");

+       if (opts->switch_to)
+               add_var(&script_snippet, "switch_to", opts->switch_to);

 
        switch (opts->type) {
        case REBASE_AM:
 
        switch (opts->type) {
        case REBASE_AM:


@@ -564,9 +567,23 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
         * orig_head -- commit object name of tip of the branch before rebasing
         * head_name -- refs/heads/<that-branch> or NULL (detached HEAD)
         */
         * orig_head -- commit object name of tip of the branch before rebasing
         * head_name -- refs/heads/<that-branch> or NULL (detached HEAD)
         */

-       if (argc > 0)
-                die("TODO: handle switch_to");
-       else {
+       if (argc == 1) {
+               /* Is it "rebase other branchname" or "rebase other commit"? */
+               branch_name = argv[0];
+               options.switch_to = argv[0];
+
+               /* Is it a local branch? */
+               strbuf_reset(&buf);
+               strbuf_addf(&buf, "refs/heads/%s", branch_name);
+               if (!read_ref(buf.buf, &options.orig_head))
+                       options.head_name = xstrdup(buf.buf);
+               /* If not is it a valid ref (branch or commit)? */
+               else if (!get_oid(branch_name, &options.orig_head))
+                       options.head_name = NULL;
+               else
+                       die(_("fatal: no such branch/commit '%s'"),
+                           branch_name);
+       } else if (argc == 0) {

                /* Do not need to switch branches, we are already on it. */
                options.head_name =
                        xstrdup_or_null(resolve_ref_unsafe("HEAD", 0, NULL,
                /* Do not need to switch branches, we are already on it. */
                options.head_name =
                        xstrdup_or_null(resolve_ref_unsafe("HEAD", 0, NULL,


@@ -585,7 +602,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                }
                if (get_oid("HEAD", &options.orig_head))
                        die(_("Could not resolve HEAD to a revision"));
                }
                if (get_oid("HEAD", &options.orig_head))
                        die(_("Could not resolve HEAD to a revision"));

-       }
+       } else
+               BUG("unexpected number of arguments left to parse");

 
        if (read_index(the_repository->index) < 0)
                die(_("could not read index"));
 
        if (read_index(the_repository->index) < 0)
                die(_("could not read index"));


@@ -612,6 +630,28 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                int flag;
 
                if (!(options.flags & REBASE_FORCE)) {
                int flag;
 
                if (!(options.flags & REBASE_FORCE)) {

+                       /* Lazily switch to the target branch if needed... */
+                       if (options.switch_to) {
+                               struct object_id oid;
+
+                               if (get_oid(options.switch_to, &oid) < 0) {
+                                       ret = !!error(_("could not parse '%s'"),
+                                                     options.switch_to);
+                                       goto cleanup;
+                               }
+
+                               strbuf_reset(&buf);
+                               strbuf_addf(&buf, "rebase: checkout %s",
+                                           options.switch_to);
+                               if (reset_head(&oid, "checkout",
+                                              options.head_name, 0) < 0) {
+                                       ret = !!error(_("could not switch to "
+                                                       "%s"),
+                                                     options.switch_to);
+                                       goto cleanup;
+                               }
+                       }
+

                        if (!(options.flags & REBASE_NO_QUIET))
                                ; /* be quiet */
                        else if (!strcmp(branch_name, "HEAD") &&
                        if (!(options.flags & REBASE_NO_QUIET))
                                ; /* be quiet */
                        else if (!strcmp(branch_name, "HEAD") &&