l10n: git.pot: v2.10.0 round 2 (12 new, 44 removed)
[gitweb.git] / builtin / merge.c
index c638fd5a9a8165c58d46d4edeeb0f3bbe8c0f9a1..0ae099f746680e5c2fcc55dff56624da1619f2f1 100644 (file)
@@ -30,6 +30,7 @@
 #include "fmt-merge-msg.h"
 #include "gpg-interface.h"
 #include "sequencer.h"
+#include "string-list.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)
@@ -42,8 +43,8 @@ struct strategy {
 };
 
 static const char * const builtin_merge_usage[] = {
-       N_("git merge [options] [<commit>...]"),
-       N_("git merge [options] <msg> HEAD <commit>"),
+       N_("git merge [<options>] [<commit>...]"),
+       N_("git merge [<options>] <msg> HEAD <commit>"),
        N_("git merge --abort"),
        NULL
 };
@@ -64,6 +65,7 @@ static int option_renormalize;
 static int verbosity;
 static int allow_rerere_auto;
 static int abort_current_merge;
+static int allow_unrelated_histories;
 static int show_progress = -1;
 static int default_to_upstream = 1;
 static const char *sign_commit;
@@ -210,7 +212,7 @@ static struct option builtin_merge_options[] = {
                PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, FF_ONLY },
        OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
        OPT_BOOL(0, "verify-signatures", &verify_signatures,
-               N_("Verify that the named commit has a valid GPG signature")),
+               N_("verify that the named commit has a valid GPG signature")),
        OPT_CALLBACK('s', "strategy", &use_strategies, N_("strategy"),
                N_("merge strategy to use"), option_parse_strategy),
        OPT_CALLBACK('X', "strategy-option", &xopts, N_("option=value"),
@@ -221,6 +223,8 @@ static struct option builtin_merge_options[] = {
        OPT__VERBOSITY(&verbosity),
        OPT_BOOL(0, "abort", &abort_current_merge,
                N_("abort the current in-progress merge")),
+       OPT_BOOL(0, "allow-unrelated-histories", &allow_unrelated_histories,
+                N_("allow merging unrelated histories")),
        OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
        { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key-id"),
          N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
@@ -231,9 +235,9 @@ static struct option builtin_merge_options[] = {
 /* Cleans up metadata that is uninteresting after a succeeded merge. */
 static void drop_save(void)
 {
-       unlink(git_path("MERGE_HEAD"));
-       unlink(git_path("MERGE_MSG"));
-       unlink(git_path("MERGE_MODE"));
+       unlink(git_path_merge_head());
+       unlink(git_path_merge_msg());
+       unlink(git_path_merge_mode());
 }
 
 static int save_state(unsigned char *stash)
@@ -333,15 +337,9 @@ static void squash_message(struct commit *commit, struct commit_list *remotehead
        struct rev_info rev;
        struct strbuf out = STRBUF_INIT;
        struct commit_list *j;
-       const char *filename;
-       int fd;
        struct pretty_print_context ctx = {0};
 
        printf(_("Squash commit -- not updating HEAD\n"));
-       filename = git_path("SQUASH_MSG");
-       fd = open(filename, O_WRONLY | O_CREAT, 0666);
-       if (fd < 0)
-               die_errno(_("Could not write to '%s'"), filename);
 
        init_revisions(&rev, NULL);
        rev.ignore_merges = 1;
@@ -365,13 +363,10 @@ static void squash_message(struct commit *commit, struct commit_list *remotehead
        while ((commit = get_revision(&rev)) != NULL) {
                strbuf_addch(&out, '\n');
                strbuf_addf(&out, "commit %s\n",
-                       sha1_to_hex(commit->object.sha1));
+                       oid_to_hex(&commit->object.oid));
                pretty_print_commit(&ctx, commit, &out);
        }
-       if (write_in_full(fd, out.buf, out.len) != out.len)
-               die_errno(_("Writing SQUASH_MSG"));
-       if (close(fd))
-               die_errno(_("Finishing SQUASH_MSG"));
+       write_file_buf(git_path_squash_msg(), out.buf, out.len);
        strbuf_release(&out);
 }
 
@@ -380,7 +375,7 @@ static void finish(struct commit *head_commit,
                   const unsigned char *new_head, const char *msg)
 {
        struct strbuf reflog_message = STRBUF_INIT;
-       const unsigned char *head = head_commit->object.sha1;
+       const unsigned char *head = head_commit->object.oid.hash;
 
        if (!msg)
                strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
@@ -404,6 +399,7 @@ static void finish(struct commit *head_commit,
                         * We ignore errors in 'gc --auto', since the
                         * user should see them.
                         */
+                       close_all_packs();
                        run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
                }
        }
@@ -492,40 +488,18 @@ static void merge_name(const char *remote, struct strbuf *msg)
        }
        if (len) {
                struct strbuf truname = STRBUF_INIT;
-               strbuf_addstr(&truname, "refs/heads/");
-               strbuf_addstr(&truname, remote);
+               strbuf_addf(&truname, "refs/heads/%s", remote);
                strbuf_setlen(&truname, truname.len - len);
                if (ref_exists(truname.buf)) {
                        strbuf_addf(msg,
                                    "%s\t\tbranch '%s'%s of .\n",
-                                   sha1_to_hex(remote_head->object.sha1),
+                                   oid_to_hex(&remote_head->object.oid),
                                    truname.buf + 11,
                                    (early ? " (early part)" : ""));
                        strbuf_release(&truname);
                        goto cleanup;
                }
-       }
-
-       if (!strcmp(remote, "FETCH_HEAD") &&
-                       !access(git_path("FETCH_HEAD"), R_OK)) {
-               const char *filename;
-               FILE *fp;
-               struct strbuf line = STRBUF_INIT;
-               char *ptr;
-
-               filename = git_path("FETCH_HEAD");
-               fp = fopen(filename, "r");
-               if (!fp)
-                       die_errno(_("could not open '%s' for reading"),
-                                 filename);
-               strbuf_getline(&line, fp, '\n');
-               fclose(fp);
-               ptr = strstr(line.buf, "\tnot-for-merge\t");
-               if (ptr)
-                       strbuf_remove(&line, ptr-line.buf+1, 13);
-               strbuf_addbuf(msg, &line);
-               strbuf_release(&line);
-               goto cleanup;
+               strbuf_release(&truname);
        }
 
        if (remote_head->util) {
@@ -533,7 +507,7 @@ static void merge_name(const char *remote, struct strbuf *msg)
                desc = merge_remote_util(remote_head);
                if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
                        strbuf_addf(msg, "%s\t\t%s '%s'\n",
-                                   sha1_to_hex(desc->obj->sha1),
+                                   oid_to_hex(&desc->obj->oid),
                                    typename(desc->obj->type),
                                    remote);
                        goto cleanup;
@@ -541,7 +515,7 @@ static void merge_name(const char *remote, struct strbuf *msg)
        }
 
        strbuf_addf(msg, "%s\t\tcommit '%s'\n",
-               sha1_to_hex(remote_head->object.sha1), remote);
+               oid_to_hex(&remote_head->object.oid), remote);
 cleanup:
        strbuf_release(&buf);
        strbuf_release(&bname);
@@ -700,6 +674,8 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
                hold_locked_index(&lock, 1);
                clean = merge_recursive(&o, head,
                                remoteheads->item, reversed, &result);
+               if (clean < 0)
+                       exit(128);
                if (active_cache_changed &&
                    write_locked_index(&the_index, &lock, COMMIT_LOCK))
                        die (_("unable to write %s"), get_index_file());
@@ -730,42 +706,17 @@ static int count_unmerged_entries(void)
        return ret;
 }
 
-static void split_merge_strategies(const char *string, struct strategy **list,
-                                  int *nr, int *alloc)
-{
-       char *p, *q, *buf;
-
-       if (!string)
-               return;
-
-       buf = xstrdup(string);
-       q = buf;
-       for (;;) {
-               p = strchr(q, ' ');
-               if (!p) {
-                       ALLOC_GROW(*list, *nr + 1, *alloc);
-                       (*list)[(*nr)++].name = xstrdup(q);
-                       free(buf);
-                       return;
-               } else {
-                       *p = '\0';
-                       ALLOC_GROW(*list, *nr + 1, *alloc);
-                       (*list)[(*nr)++].name = xstrdup(q);
-                       q = ++p;
-               }
-       }
-}
-
 static void add_strategies(const char *string, unsigned attr)
 {
-       struct strategy *list = NULL;
-       int list_alloc = 0, list_nr = 0, i;
-
-       memset(&list, 0, sizeof(list));
-       split_merge_strategies(string, &list, &list_nr, &list_alloc);
-       if (list) {
-               for (i = 0; i < list_nr; i++)
-                       append_strategy(get_strategy(list[i].name));
+       int i;
+
+       if (string) {
+               struct string_list list = STRING_LIST_INIT_DUP;
+               struct string_list_item *item;
+               string_list_split(&list, string, ' ', -1);
+               for_each_string_list_item(item, &list)
+                       append_strategy(get_strategy(item->string));
+               string_list_clear(&list, 0);
                return;
        }
        for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
@@ -774,21 +725,9 @@ static void add_strategies(const char *string, unsigned attr)
 
 }
 
-static void write_merge_msg(struct strbuf *msg)
-{
-       const char *filename = git_path("MERGE_MSG");
-       int fd = open(filename, O_WRONLY | O_CREAT, 0666);
-       if (fd < 0)
-               die_errno(_("Could not open '%s' for writing"),
-                         filename);
-       if (write_in_full(fd, msg->buf, msg->len) != msg->len)
-               die_errno(_("Could not write to '%s'"), filename);
-       close(fd);
-}
-
 static void read_merge_msg(struct strbuf *msg)
 {
-       const char *filename = git_path("MERGE_MSG");
+       const char *filename = git_path_merge_msg();
        strbuf_reset(msg);
        if (strbuf_read_file(msg, filename, 0) < 0)
                die_errno(_("Could not read from '%s'"), filename);
@@ -819,16 +758,16 @@ static void prepare_to_commit(struct commit_list *remoteheads)
        strbuf_addch(&msg, '\n');
        if (0 < option_edit)
                strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
-       write_merge_msg(&msg);
+       write_file_buf(git_path_merge_msg(), msg.buf, msg.len);
        if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
-                           git_path("MERGE_MSG"), "merge", NULL))
+                           git_path_merge_msg(), "merge", NULL))
                abort_commit(remoteheads, NULL);
        if (0 < option_edit) {
-               if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
+               if (launch_editor(git_path_merge_msg(), NULL, NULL))
                        abort_commit(remoteheads, NULL);
        }
        read_merge_msg(&msg);
-       stripspace(&msg, 0 < option_edit);
+       strbuf_stripspace(&msg, 0 < option_edit);
        if (!msg.len)
                abort_commit(remoteheads, _("Empty commit message."));
        strbuf_release(&merge_msg);
@@ -840,6 +779,14 @@ static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 {
        unsigned char result_tree[20], result_commit[20];
        struct commit_list *parents, **pptr = &parents;
+       static struct lock_file lock;
+
+       hold_locked_index(&lock, 1);
+       refresh_cache(REFRESH_QUIET);
+       if (active_cache_changed &&
+           write_locked_index(&the_index, &lock, COMMIT_LOCK))
+               return error(_("Unable to write index."));
+       rollback_lock_file(&lock);
 
        write_tree_trivial(result_tree);
        printf(_("Wonderful.\n"));
@@ -887,7 +834,7 @@ static int suggest_conflicts(void)
        FILE *fp;
        struct strbuf msgbuf = STRBUF_INIT;
 
-       filename = git_path("MERGE_MSG");
+       filename = git_path_merge_msg();
        fp = fopen(filename, "a");
        if (!fp)
                die_errno(_("Could not open '%s' for writing"), filename);
@@ -914,7 +861,7 @@ static struct commit *is_old_style_invocation(int argc, const char **argv,
                second_token = lookup_commit_reference_gently(second_sha1, 0);
                if (!second_token)
                        die(_("'%s' is not a commit"), argv[1]);
-               if (hashcmp(second_token->object.sha1, head))
+               if (hashcmp(second_token->object.oid.hash, head))
                        return NULL;
        }
        return second_token;
@@ -955,12 +902,12 @@ static int setup_with_upstream(const char ***argv)
 
        if (!branch)
                die(_("No current branch."));
-       if (!branch->remote)
+       if (!branch->remote_name)
                die(_("No remote for the current branch."));
        if (!branch->merge_nr)
                die(_("No default upstream defined for the current branch."));
 
-       args = xcalloc(branch->merge_nr + 1, sizeof(char *));
+       args = xcalloc(st_add(branch->merge_nr, 1), sizeof(char *));
        for (i = 0; i < branch->merge_nr; i++) {
                if (!branch->merge[i]->dst)
                        die(_("No remote-tracking branch for %s from %s"),
@@ -974,41 +921,27 @@ static int setup_with_upstream(const char ***argv)
 
 static void write_merge_state(struct commit_list *remoteheads)
 {
-       const char *filename;
-       int fd;
        struct commit_list *j;
        struct strbuf buf = STRBUF_INIT;
 
        for (j = remoteheads; j; j = j->next) {
-               unsigned const char *sha1;
+               struct object_id *oid;
                struct commit *c = j->item;
                if (c->util && merge_remote_util(c)->obj) {
-                       sha1 = merge_remote_util(c)->obj->sha1;
+                       oid = &merge_remote_util(c)->obj->oid;
                } else {
-                       sha1 = c->object.sha1;
+                       oid = &c->object.oid;
                }
-               strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
+               strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
        }
-       filename = git_path("MERGE_HEAD");
-       fd = open(filename, O_WRONLY | O_CREAT, 0666);
-       if (fd < 0)
-               die_errno(_("Could not open '%s' for writing"), filename);
-       if (write_in_full(fd, buf.buf, buf.len) != buf.len)
-               die_errno(_("Could not write to '%s'"), filename);
-       close(fd);
+       write_file_buf(git_path_merge_head(), buf.buf, buf.len);
        strbuf_addch(&merge_msg, '\n');
-       write_merge_msg(&merge_msg);
+       write_file_buf(git_path_merge_msg(), merge_msg.buf, merge_msg.len);
 
-       filename = git_path("MERGE_MODE");
-       fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
-       if (fd < 0)
-               die_errno(_("Could not open '%s' for writing"), filename);
        strbuf_reset(&buf);
        if (fast_forward == FF_NO)
                strbuf_addf(&buf, "no-ff");
-       if (write_in_full(fd, buf.buf, buf.len) != buf.len)
-               die_errno(_("Could not write to '%s'"), filename);
-       close(fd);
+       write_file_buf(git_path_merge_mode(), buf.buf, buf.len);
 }
 
 static int default_edit_option(void)
@@ -1024,7 +957,7 @@ static int default_edit_option(void)
        if (e) {
                int v = git_config_maybe_bool(name, e);
                if (v < 0)
-                       die("Bad value '%s' in environment '%s'", e, name);
+                       die(_("Bad value '%s' in environment '%s'"), e, name);
                return v;
        }
 
@@ -1037,38 +970,144 @@ static int default_edit_option(void)
                st_stdin.st_mode == st_stdout.st_mode);
 }
 
+static struct commit_list *reduce_parents(struct commit *head_commit,
+                                         int *head_subsumed,
+                                         struct commit_list *remoteheads)
+{
+       struct commit_list *parents, **remotes;
+
+       /*
+        * Is the current HEAD reachable from another commit being
+        * merged?  If so we do not want to record it as a parent of
+        * the resulting merge, unless --no-ff is given.  We will flip
+        * this variable to 0 when we find HEAD among the independent
+        * tips being merged.
+        */
+       *head_subsumed = 1;
+
+       /* Find what parents to record by checking independent ones. */
+       parents = reduce_heads(remoteheads);
+
+       remoteheads = NULL;
+       remotes = &remoteheads;
+       while (parents) {
+               struct commit *commit = pop_commit(&parents);
+               if (commit == head_commit)
+                       *head_subsumed = 0;
+               else
+                       remotes = &commit_list_insert(commit, remotes)->next;
+       }
+       return remoteheads;
+}
+
+static void prepare_merge_message(struct strbuf *merge_names, struct strbuf *merge_msg)
+{
+       struct fmt_merge_msg_opts opts;
+
+       memset(&opts, 0, sizeof(opts));
+       opts.add_title = !have_message;
+       opts.shortlog_len = shortlog_len;
+       opts.credit_people = (0 < option_edit);
+
+       fmt_merge_msg(merge_names, merge_msg, &opts);
+       if (merge_msg->len)
+               strbuf_setlen(merge_msg, merge_msg->len - 1);
+}
+
+static void handle_fetch_head(struct commit_list **remotes, struct strbuf *merge_names)
+{
+       const char *filename;
+       int fd, pos, npos;
+       struct strbuf fetch_head_file = STRBUF_INIT;
+
+       if (!merge_names)
+               merge_names = &fetch_head_file;
+
+       filename = git_path_fetch_head();
+       fd = open(filename, O_RDONLY);
+       if (fd < 0)
+               die_errno(_("could not open '%s' for reading"), filename);
+
+       if (strbuf_read(merge_names, fd, 0) < 0)
+               die_errno(_("could not read '%s'"), filename);
+       if (close(fd) < 0)
+               die_errno(_("could not close '%s'"), filename);
+
+       for (pos = 0; pos < merge_names->len; pos = npos) {
+               unsigned char sha1[20];
+               char *ptr;
+               struct commit *commit;
+
+               ptr = strchr(merge_names->buf + pos, '\n');
+               if (ptr)
+                       npos = ptr - merge_names->buf + 1;
+               else
+                       npos = merge_names->len;
+
+               if (npos - pos < 40 + 2 ||
+                   get_sha1_hex(merge_names->buf + pos, sha1))
+                       commit = NULL; /* bad */
+               else if (memcmp(merge_names->buf + pos + 40, "\t\t", 2))
+                       continue; /* not-for-merge */
+               else {
+                       char saved = merge_names->buf[pos + 40];
+                       merge_names->buf[pos + 40] = '\0';
+                       commit = get_merge_parent(merge_names->buf + pos);
+                       merge_names->buf[pos + 40] = saved;
+               }
+               if (!commit) {
+                       if (ptr)
+                               *ptr = '\0';
+                       die(_("not something we can merge in %s: %s"),
+                           filename, merge_names->buf + pos);
+               }
+               remotes = &commit_list_insert(commit, remotes)->next;
+       }
+
+       if (merge_names == &fetch_head_file)
+               strbuf_release(&fetch_head_file);
+}
+
 static struct commit_list *collect_parents(struct commit *head_commit,
                                           int *head_subsumed,
-                                          int argc, const char **argv)
+                                          int argc, const char **argv,
+                                          struct strbuf *merge_msg)
 {
        int i;
-       struct commit_list *remoteheads = NULL, *parents, *next;
+       struct commit_list *remoteheads = NULL;
        struct commit_list **remotes = &remoteheads;
+       struct strbuf merge_names = STRBUF_INIT, *autogen = NULL;
+
+       if (merge_msg && (!have_message || shortlog_len))
+               autogen = &merge_names;
 
        if (head_commit)
                remotes = &commit_list_insert(head_commit, remotes)->next;
-       for (i = 0; i < argc; i++) {
-               struct commit *commit = get_merge_parent(argv[i]);
-               if (!commit)
-                       help_unknown_ref(argv[i], "merge",
-                                        "not something we can merge");
-               remotes = &commit_list_insert(commit, remotes)->next;
-       }
-       *remotes = NULL;
-
-       parents = reduce_heads(remoteheads);
 
-       *head_subsumed = 1; /* we will flip this to 0 when we find it */
-       for (remoteheads = NULL, remotes = &remoteheads;
-            parents;
-            parents = next) {
-               struct commit *commit = parents->item;
-               next = parents->next;
-               if (commit == head_commit)
-                       *head_subsumed = 0;
-               else
+       if (argc == 1 && !strcmp(argv[0], "FETCH_HEAD")) {
+               handle_fetch_head(remotes, autogen);
+               remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
+       } else {
+               for (i = 0; i < argc; i++) {
+                       struct commit *commit = get_merge_parent(argv[i]);
+                       if (!commit)
+                               help_unknown_ref(argv[i], "merge",
+                                                _("not something we can merge"));
                        remotes = &commit_list_insert(commit, remotes)->next;
+               }
+               remoteheads = reduce_parents(head_commit, head_subsumed, remoteheads);
+               if (autogen) {
+                       struct commit_list *p;
+                       for (p = remoteheads; p; p = p->next)
+                               merge_name(merge_remote_util(p->item)->name, autogen);
+               }
+       }
+
+       if (autogen) {
+               prepare_merge_message(autogen, merge_msg);
+               strbuf_release(autogen);
        }
+
        return remoteheads;
 }
 
@@ -1080,7 +1119,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        struct commit *head_commit;
        struct strbuf buf = STRBUF_INIT;
        const char *head_arg;
-       int flag, i, ret = 0, head_subsumed;
+       int i, ret = 0, head_subsumed;
        int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
        struct commit_list *common = NULL;
        const char *best_strategy = NULL, *wt_strategy = NULL;
@@ -1094,7 +1133,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
         * Check if we are _not_ on a detached HEAD, i.e. if there is a
         * current branch.
         */
-       branch = branch_to_free = resolve_refdup("HEAD", 0, head_sha1, &flag);
+       branch = branch_to_free = resolve_refdup("HEAD", 0, head_sha1, NULL);
        if (branch && starts_with(branch, "refs/heads/"))
                branch += 11;
        if (!branch || is_null_sha1(head_sha1))
@@ -1102,6 +1141,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        else
                head_commit = lookup_commit_or_die(head_sha1, "HEAD");
 
+       init_diff_ui_defaults();
        git_config(git_merge_config, NULL);
 
        if (branch_mergeoptions)
@@ -1118,7 +1158,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                int nargc = 2;
                const char *nargv[] = {"reset", "--merge", NULL};
 
-               if (!file_exists(git_path("MERGE_HEAD")))
+               if (!file_exists(git_path_merge_head()))
                        die(_("There is no merge to abort (MERGE_HEAD missing)."));
 
                /* Invoke 'git reset --merge' */
@@ -1129,7 +1169,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        if (read_cache_unmerged())
                die_resolve_conflict("merge");
 
-       if (file_exists(git_path("MERGE_HEAD"))) {
+       if (file_exists(git_path_merge_head())) {
                /*
                 * There is no unmerged entry, don't advise 'git
                 * add/rm <file>', just 'git commit'.
@@ -1140,7 +1180,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                else
                        die(_("You have not concluded your merge (MERGE_HEAD exists)."));
        }
-       if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
+       if (file_exists(git_path_cherry_pick_head())) {
                if (advice_resolve_conflict)
                        die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
                            "Please, commit your changes before you merge."));
@@ -1158,61 +1198,62 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                option_commit = 0;
        }
 
-       if (!abort_current_merge) {
-               if (!argc) {
-                       if (default_to_upstream)
-                               argc = setup_with_upstream(&argv);
-                       else
-                               die(_("No commit specified and merge.defaultToUpstream not set."));
-               } else if (argc == 1 && !strcmp(argv[0], "-"))
-                       argv[0] = "@{-1}";
+       if (!argc) {
+               if (default_to_upstream)
+                       argc = setup_with_upstream(&argv);
+               else
+                       die(_("No commit specified and merge.defaultToUpstream not set."));
+       } else if (argc == 1 && !strcmp(argv[0], "-")) {
+               argv[0] = "@{-1}";
        }
+
        if (!argc)
                usage_with_options(builtin_merge_usage,
                        builtin_merge_options);
 
-       /*
-        * This could be traditional "merge <msg> HEAD <commit>..."  and
-        * the way we can tell it is to see if the second token is HEAD,
-        * but some people might have misused the interface and used a
-        * commit-ish that is the same as HEAD there instead.
-        * Traditional format never would have "-m" so it is an
-        * additional safety measure to check for it.
-        */
-
-       if (!have_message && head_commit &&
-           is_old_style_invocation(argc, argv, head_commit->object.sha1)) {
-               strbuf_addstr(&merge_msg, argv[0]);
-               head_arg = argv[1];
-               argv += 2;
-               argc -= 2;
-               remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
-       } else if (!head_commit) {
-               struct commit *remote_head;
+       if (!head_commit) {
                /*
                 * If the merged head is a valid one there is no reason
                 * to forbid "git merge" into a branch yet to be born.
                 * We do the same for "git pull".
                 */
-               if (argc != 1)
-                       die(_("Can merge only exactly one commit into "
-                               "empty head"));
+               unsigned char *remote_head_sha1;
                if (squash)
                        die(_("Squash commit into empty head not supported yet"));
                if (fast_forward == FF_NO)
                        die(_("Non-fast-forward commit does not make sense into "
                            "an empty head"));
-               remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
-               remote_head = remoteheads->item;
-               if (!remote_head)
+               remoteheads = collect_parents(head_commit, &head_subsumed,
+                                             argc, argv, NULL);
+               if (!remoteheads)
                        die(_("%s - not something we can merge"), argv[0]);
-               read_empty(remote_head->object.sha1, 0);
-               update_ref("initial pull", "HEAD", remote_head->object.sha1,
+               if (remoteheads->next)
+                       die(_("Can merge only exactly one commit into empty head"));
+               remote_head_sha1 = remoteheads->item->object.oid.hash;
+               read_empty(remote_head_sha1, 0);
+               update_ref("initial pull", "HEAD", remote_head_sha1,
                           NULL, 0, UPDATE_REFS_DIE_ON_ERR);
                goto done;
-       } else {
-               struct strbuf merge_names = STRBUF_INIT;
+       }
 
+       /*
+        * This could be traditional "merge <msg> HEAD <commit>..."  and
+        * the way we can tell it is to see if the second token is HEAD,
+        * but some people might have misused the interface and used a
+        * commit-ish that is the same as HEAD there instead.
+        * Traditional format never would have "-m" so it is an
+        * additional safety measure to check for it.
+        */
+       if (!have_message &&
+           is_old_style_invocation(argc, argv, head_commit->object.oid.hash)) {
+               warning("old-style 'git merge <msg> HEAD <commit>' is deprecated.");
+               strbuf_addstr(&merge_msg, argv[0]);
+               head_arg = argv[1];
+               argv += 2;
+               argc -= 2;
+               remoteheads = collect_parents(head_commit, &head_subsumed,
+                                             argc, argv, NULL);
+       } else {
                /* We are invoked directly as the first-class UI. */
                head_arg = "HEAD";
 
@@ -1221,21 +1262,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                 * the standard merge summary message to be appended
                 * to the given message.
                 */
-               remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
-               for (p = remoteheads; p; p = p->next)
-                       merge_name(merge_remote_util(p->item)->name, &merge_names);
-
-               if (!have_message || shortlog_len) {
-                       struct fmt_merge_msg_opts opts;
-                       memset(&opts, 0, sizeof(opts));
-                       opts.add_title = !have_message;
-                       opts.shortlog_len = shortlog_len;
-                       opts.credit_people = (0 < option_edit);
-
-                       fmt_merge_msg(&merge_names, &merge_msg, &opts);
-                       if (merge_msg.len)
-                               strbuf_setlen(&merge_msg, merge_msg.len - 1);
-               }
+               remoteheads = collect_parents(head_commit, &head_subsumed,
+                                             argc, argv, &merge_msg);
        }
 
        if (!head_commit || !argc)
@@ -1245,13 +1273,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        if (verify_signatures) {
                for (p = remoteheads; p; p = p->next) {
                        struct commit *commit = p->item;
-                       char hex[41];
+                       char hex[GIT_SHA1_HEXSZ + 1];
                        struct signature_check signature_check;
                        memset(&signature_check, 0, sizeof(signature_check));
 
                        check_commit_signature(commit, &signature_check);
 
-                       strcpy(hex, find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
+                       find_unique_abbrev_r(hex, commit->object.oid.hash, DEFAULT_ABBREV);
                        switch (signature_check.result) {
                        case 'G':
                                break;
@@ -1281,7 +1309,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        for (p = remoteheads; p; p = p->next) {
                struct commit *commit = p->item;
                strbuf_addf(&buf, "GITHEAD_%s",
-                           sha1_to_hex(commit->object.sha1));
+                           oid_to_hex(&commit->object.oid));
                setenv(buf.buf, merge_remote_util(commit)->name, 1);
                strbuf_reset(&buf);
                if (fast_forward != FF_ONLY &&
@@ -1321,35 +1349,38 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                free(list);
        }
 
-       update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
+       update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.oid.hash,
                   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
 
-       if (remoteheads && !common)
-               ; /* No common ancestors found. We need a real merge. */
-       else if (!remoteheads ||
+       if (remoteheads && !common) {
+               /* No common ancestors found. */
+               if (!allow_unrelated_histories)
+                       die(_("refusing to merge unrelated histories"));
+               /* otherwise, we need a real merge. */
+       } else if (!remoteheads ||
                 (!remoteheads->next && !common->next &&
                  common->item == remoteheads->item)) {
                /*
                 * If head can reach all the merge then we are up to date.
                 * but first the most common case of merging one remote.
                 */
-               finish_up_to_date("Already up-to-date.");
+               finish_up_to_date(_("Already up-to-date."));
                goto done;
        } else if (fast_forward != FF_NO && !remoteheads->next &&
                        !common->next &&
-                       !hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
+                       !oidcmp(&common->item->object.oid, &head_commit->object.oid)) {
                /* Again the most common case of merging one remote. */
                struct strbuf msg = STRBUF_INIT;
                struct commit *commit;
-               char hex[41];
-
-               strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));
 
-               if (verbosity >= 0)
-                       printf(_("Updating %s..%s\n"),
-                               hex,
-                               find_unique_abbrev(remoteheads->item->object.sha1,
-                               DEFAULT_ABBREV));
+               if (verbosity >= 0) {
+                       char from[GIT_SHA1_HEXSZ + 1], to[GIT_SHA1_HEXSZ + 1];
+                       find_unique_abbrev_r(from, head_commit->object.oid.hash,
+                                             DEFAULT_ABBREV);
+                       find_unique_abbrev_r(to, remoteheads->item->object.oid.hash,
+                                             DEFAULT_ABBREV);
+                       printf(_("Updating %s..%s\n"), from, to);
+               }
                strbuf_addstr(&msg, "Fast-forward");
                if (have_message)
                        strbuf_addstr(&msg,
@@ -1360,14 +1391,14 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                        goto done;
                }
 
-               if (checkout_fast_forward(head_commit->object.sha1,
-                                         commit->object.sha1,
+               if (checkout_fast_forward(head_commit->object.oid.hash,
+                                         commit->object.oid.hash,
                                          overwrite_ignore)) {
                        ret = 1;
                        goto done;
                }
 
-               finish(head_commit, remoteheads, commit->object.sha1, msg.buf);
+               finish(head_commit, remoteheads, commit->object.oid.hash, msg.buf);
                drop_save();
                goto done;
        } else if (!remoteheads->next && common->next)
@@ -1386,9 +1417,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                        /* See if it is really trivial. */
                        git_committer_info(IDENT_STRICT);
                        printf(_("Trying really trivial in-index merge...\n"));
-                       if (!read_tree_trivial(common->item->object.sha1,
-                                              head_commit->object.sha1,
-                                              remoteheads->item->object.sha1)) {
+                       if (!read_tree_trivial(common->item->object.oid.hash,
+                                              head_commit->object.oid.hash,
+                                              remoteheads->item->object.oid.hash)) {
                                ret = merge_trivial(head_commit, remoteheads);
                                goto done;
                        }
@@ -1411,14 +1442,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                         * HEAD^^" would be missed.
                         */
                        common_one = get_merge_bases(head_commit, j->item);
-                       if (hashcmp(common_one->item->object.sha1,
-                               j->item->object.sha1)) {
+                       if (oidcmp(&common_one->item->object.oid, &j->item->object.oid)) {
                                up_to_date = 0;
                                break;
                        }
                }
                if (up_to_date) {
-                       finish_up_to_date("Already up-to-date. Yeeah!");
+                       finish_up_to_date(_("Already up-to-date. Yeeah!"));
                        goto done;
                }
        }
@@ -1442,13 +1472,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
             * Stash away the local changes so that we can try more than one.
             */
            save_state(stash))
-               hashcpy(stash, null_sha1);
+               hashclr(stash);
 
        for (i = 0; i < use_strategies_nr; i++) {
                int ret;
                if (i) {
                        printf(_("Rewinding the tree to pristine...\n"));
-                       restore_state(head_commit->object.sha1, stash);
+                       restore_state(head_commit->object.oid.hash, stash);
                }
                if (use_strategies_nr != 1)
                        printf(_("Trying merge strategy %s...\n"),
@@ -1514,7 +1544,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
         * it up.
         */
        if (!best_strategy) {
-               restore_state(head_commit->object.sha1, stash);
+               restore_state(head_commit->object.oid.hash, stash);
                if (use_strategies_nr > 1)
                        fprintf(stderr,
                                _("No merge strategy handled the merge.\n"));
@@ -1527,7 +1557,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                ; /* We already have its result in the working tree. */
        else {
                printf(_("Rewinding the tree to pristine...\n"));
-               restore_state(head_commit->object.sha1, stash);
+               restore_state(head_commit->object.oid.hash, stash);
                printf(_("Using the %s to prepare resolving by hand.\n"),
                        best_strategy);
                try_merge_strategy(best_strategy, common, remoteheads,