rebase: fast-forward --onto in more cases

diff --git a/builtin/rebase.c b/builtin/rebase.c
index 2748fa6f2e91d2b788d5b54edfb15de29d8aa833..1e1406c8ba59e6ff90392480de2b67fc67635049 100644 (file)
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -508,7 +508,7 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
        if (argc == 1)
                usage_with_options(builtin_rebase_interactive_usage, options);
 
-       argc = parse_options(argc, argv, NULL, options,
+       argc = parse_options(argc, argv, prefix, options,
                        builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);
 
        if (!is_null_oid(&squash_onto))
@@ -850,13 +850,13 @@ static int reset_head(struct object_id *oid, const char *action,
                goto leave_reset_head;
        }
 
-       if (!reset_hard && !fill_tree_descriptor(&desc[nr++], &head_oid)) {
+       if (!reset_hard && !fill_tree_descriptor(the_repository, &desc[nr++], &head_oid)) {
                ret = error(_("failed to find tree of %s"),
                            oid_to_hex(&head_oid));
                goto leave_reset_head;
        }
 
-       if (!fill_tree_descriptor(&desc[nr++], oid)) {
+       if (!fill_tree_descriptor(the_repository, &desc[nr++], oid)) {
                ret = error(_("failed to find tree of %s"), oid_to_hex(oid));
                goto leave_reset_head;
        }
@@ -1163,10 +1163,6 @@ static int run_specific_rebase(struct rebase_options *opts, enum action action)
        }
 
        switch (opts->type) {
-       case REBASE_AM:
-               backend = "git-rebase--am";
-               backend_func = "git_rebase__am";
-               break;
        case REBASE_PRESERVE_MERGES:
                backend = "git-rebase--preserve-merges";
                backend_func = "git_rebase__preserve_merges";
@@ -1177,8 +1173,7 @@ static int run_specific_rebase(struct rebase_options *opts, enum action action)
        }
 
        strbuf_addf(&script_snippet,
-                   ". git-sh-setup && . git-rebase--common &&"
-                   " . %s && %s", backend, backend_func);
+                   ". git-sh-setup && . %s && %s", backend, backend_func);
        argv[0] = script_snippet.buf;
 
        status = run_command_v_opt(argv, RUN_USING_SHELL);
@@ -1265,24 +1260,40 @@ static int is_linear_history(struct commit *from, struct commit *to)
        return 1;
 }
 
-static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
-                           struct object_id *merge_base)
+static int can_fast_forward(struct commit *onto, struct commit *upstream,
+                           struct object_id *head_oid, struct object_id *merge_base)
 {
        struct commit *head = lookup_commit(the_repository, head_oid);
-       struct commit_list *merge_bases;
-       int res;
+       struct commit_list *merge_bases = NULL;
+       int res = 0;
 
        if (!head)
-               return 0;
+               goto done;
 
        merge_bases = get_merge_bases(onto, head);
-       if (merge_bases && !merge_bases->next) {
-               oidcpy(merge_base, &merge_bases->item->object.oid);
-               res = oideq(merge_base, &onto->object.oid);
-       } else {
+       if (!merge_bases || merge_bases->next) {
                oidcpy(merge_base, &null_oid);
-               res = 0;
+               goto done;
        }
+
+       oidcpy(merge_base, &merge_bases->item->object.oid);
+       if (!oideq(merge_base, &onto->object.oid))
+               goto done;
+
+       if (!upstream)
+               goto done;
+
+       free_commit_list(merge_bases);
+       merge_bases = get_merge_bases(upstream, head);
+       if (!merge_bases || merge_bases->next)
+               goto done;
+
+       if (!oideq(&onto->object.oid, &merge_bases->item->object.oid))
+               goto done;
+
+       res = 1;
+
+done:
        free_commit_list(merge_bases);
        return res && is_linear_history(onto, head);
 }
@@ -1497,10 +1508,6 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                usage_with_options(builtin_rebase_usage,
                                   builtin_rebase_options);
 
-       prefix = setup_git_directory();
-       trace_repo_setup(prefix);
-       setup_work_tree();
-
        options.allow_empty_message = 1;
        git_config(rebase_config, &options);
 
@@ -1616,7 +1623,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                if (reset_head(NULL, "reset", NULL, RESET_HEAD_HARD,
                               NULL, NULL) < 0)
                        die(_("could not discard worktree changes"));
-               remove_branch_state(the_repository);
+               remove_branch_state(the_repository, 0);
                if (read_basic_state(&options))
                        exit(1);
                goto run_rebase;
@@ -1636,7 +1643,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                               NULL, NULL) < 0)
                        die(_("could not move back to %s"),
                            oid_to_hex(&options.orig_head));
-               remove_branch_state(the_repository);
+               remove_branch_state(the_repository, 0);
                ret = !!finish_rebase(&options);
                goto cleanup;
        }
@@ -2031,13 +2038,13 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 
        /*
         * Check if we are already based on onto with linear history,
-        * but this should be done only when upstream and onto are the same
-        * and if this is not an interactive rebase.
+        * in which case we could fast-forward without replacing the commits
+        * with new commits recreated by replaying their changes. This
+        * optimization must not be done if this is an interactive rebase.
         */
-       if (can_fast_forward(options.onto, &options.orig_head, &merge_base) &&
-           !is_interactive(&options) && !options.restrict_revision &&
-           options.upstream &&
-           !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) {
+       if (can_fast_forward(options.onto, options.upstream, &options.orig_head,
+                   &merge_base) &&
+           !is_interactive(&options) && !options.restrict_revision) {
                int flag;
 
                if (!(options.flags & REBASE_FORCE)) {
@@ -2131,7 +2138,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
        strbuf_addf(&msg, "%s: checkout %s",
                    getenv(GIT_REFLOG_ACTION_ENVIRONMENT), options.onto_name);
        if (reset_head(&options.onto->object.oid, "checkout", NULL,
-                      RESET_HEAD_DETACH | RESET_ORIG_HEAD | 
+                      RESET_HEAD_DETACH | RESET_ORIG_HEAD |
                       RESET_HEAD_RUN_POST_CHECKOUT_HOOK,
                       NULL, msg.buf))
                die(_("Could not detach HEAD"));