upload-pack: delegate rev walking in shallow fetch to pack-objects
[gitweb.git] / builtin / merge.c
index 8018a144688541b6ea178e96fe83206209a2902c..34a6166b520c8ede9973fbf497b21ac6ecb761ad 100644 (file)
@@ -40,19 +40,18 @@ struct strategy {
 };
 
 static const char * const builtin_merge_usage[] = {
-       "git merge [options] [<commit>...]",
-       "git merge [options] <msg> HEAD <commit>",
-       "git merge --abort",
+       N_("git merge [options] [<commit>...]"),
+       N_("git merge [options] <msg> HEAD <commit>"),
+       N_("git merge --abort"),
        NULL
 };
 
 static int show_diffstat = 1, shortlog_len = -1, squash;
-static int option_commit = 1, allow_fast_forward = 1;
-static int fast_forward_only, option_edit = -1;
-static int allow_trivial = 1, have_message;
+static int option_commit = 1;
+static int option_edit = -1;
+static int allow_trivial = 1, have_message, verify_signatures;
 static int overwrite_ignore = 1;
 static struct strbuf merge_msg = STRBUF_INIT;
-static struct commit_list *remoteheads;
 static struct strategy **use_strategies;
 static size_t use_strategies_nr, use_strategies_alloc;
 static const char **xopts;
@@ -77,6 +76,14 @@ static struct strategy all_strategy[] = {
 
 static const char *pull_twohead, *pull_octopus;
 
+enum ff_type {
+       FF_NO,
+       FF_ALLOW,
+       FF_ONLY
+};
+
+static enum ff_type fast_forward = FF_ALLOW;
+
 static int option_parse_message(const struct option *opt,
                                const char *arg, int unset)
 {
@@ -179,41 +186,50 @@ static int option_parse_n(const struct option *opt,
        return 0;
 }
 
+static int option_parse_ff_only(const struct option *opt,
+                         const char *arg, int unset)
+{
+       fast_forward = FF_ONLY;
+       return 0;
+}
+
 static struct option builtin_merge_options[] = {
        { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
-               "do not show a diffstat at the end of the merge",
+               N_("do not show a diffstat at the end of the merge"),
                PARSE_OPT_NOARG, option_parse_n },
        OPT_BOOLEAN(0, "stat", &show_diffstat,
-               "show a diffstat at the end of the merge"),
-       OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
-       { OPTION_INTEGER, 0, "log", &shortlog_len, "n",
-         "add (at most <n>) entries from shortlog to merge commit message",
+               N_("show a diffstat at the end of the merge")),
+       OPT_BOOLEAN(0, "summary", &show_diffstat, N_("(synonym to --stat)")),
+       { OPTION_INTEGER, 0, "log", &shortlog_len, N_("n"),
+         N_("add (at most <n>) entries from shortlog to merge commit message"),
          PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
        OPT_BOOLEAN(0, "squash", &squash,
-               "create a single commit instead of doing a merge"),
+               N_("create a single commit instead of doing a merge")),
        OPT_BOOLEAN(0, "commit", &option_commit,
-               "perform a commit if the merge succeeds (default)"),
+               N_("perform a commit if the merge succeeds (default)")),
        OPT_BOOL('e', "edit", &option_edit,
-               "edit message before committing"),
-       OPT_BOOLEAN(0, "ff", &allow_fast_forward,
-               "allow fast-forward (default)"),
-       OPT_BOOLEAN(0, "ff-only", &fast_forward_only,
-               "abort if fast-forward is not possible"),
+               N_("edit message before committing")),
+       OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
+       { OPTION_CALLBACK, 0, "ff-only", NULL, NULL,
+               N_("abort if fast-forward is not possible"),
+               PARSE_OPT_NOARG | PARSE_OPT_NONEG, option_parse_ff_only },
        OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
-       OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
-               "merge strategy to use", option_parse_strategy),
-       OPT_CALLBACK('X', "strategy-option", &xopts, "option=value",
-               "option for selected merge strategy", option_parse_x),
-       OPT_CALLBACK('m', "message", &merge_msg, "message",
-               "merge commit message (for a non-fast-forward merge)",
+       OPT_BOOL(0, "verify-signatures", &verify_signatures,
+               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"),
+               N_("option for selected merge strategy"), option_parse_x),
+       OPT_CALLBACK('m', "message", &merge_msg, N_("message"),
+               N_("merge commit message (for a non-fast-forward merge)"),
                option_parse_message),
        OPT__VERBOSITY(&verbosity),
        OPT_BOOLEAN(0, "abort", &abort_current_merge,
-               "abort the current in-progress merge"),
-       OPT_SET_INT(0, "progress", &show_progress, "force progress reporting", 1),
-       { OPTION_STRING, 'S', "gpg-sign", &sign_commit, "key id",
-         "GPG sign commit", PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
-       OPT_BOOLEAN(0, "overwrite-ignore", &overwrite_ignore, "update ignored files (default)"),
+               N_("abort the current in-progress merge")),
+       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) "" },
+       OPT_BOOLEAN(0, "overwrite-ignore", &overwrite_ignore, N_("update ignored files (default)")),
        OPT_END()
 };
 
@@ -318,7 +334,7 @@ static void finish_up_to_date(const char *msg)
        drop_save();
 }
 
-static void squash_message(struct commit *commit)
+static void squash_message(struct commit *commit, struct commit_list *remoteheads)
 {
        struct rev_info rev;
        struct strbuf out = STRBUF_INIT;
@@ -366,6 +382,7 @@ static void squash_message(struct commit *commit)
 }
 
 static void finish(struct commit *head_commit,
+                  struct commit_list *remoteheads,
                   const unsigned char *new_head, const char *msg)
 {
        struct strbuf reflog_message = STRBUF_INIT;
@@ -380,7 +397,7 @@ static void finish(struct commit *head_commit,
                        getenv("GIT_REFLOG_ACTION"), msg);
        }
        if (squash) {
-               squash_message(head_commit);
+               squash_message(head_commit, remoteheads);
        } else {
                if (verbosity >= 0 && !merge_msg.len)
                        printf(_("No merge message -- not updating HEAD\n"));
@@ -399,11 +416,12 @@ static void finish(struct commit *head_commit,
        if (new_head && show_diffstat) {
                struct diff_options opts;
                diff_setup(&opts);
+               opts.stat_width = -1; /* use full terminal width */
+               opts.stat_graph_width = -1; /* respect statGraphWidth config */
                opts.output_format |=
                        DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
                opts.detect_rename = DIFF_DETECT_RENAME;
-               if (diff_setup_done(&opts) < 0)
-                       die(_("diff_setup_done failed"));
+               diff_setup_done(&opts);
                diff_tree_sha1(head, new_head, "", &opts);
                diffcore_std(&opts);
                diff_flush(&opts);
@@ -515,6 +533,19 @@ static void merge_name(const char *remote, struct strbuf *msg)
                strbuf_release(&line);
                goto cleanup;
        }
+
+       if (remote_head->util) {
+               struct merge_remote_desc *desc;
+               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),
+                                   typename(desc->obj->type),
+                                   remote);
+                       goto cleanup;
+               }
+       }
+
        strbuf_addf(msg, "%s\t\tcommit '%s'\n",
                sha1_to_hex(remote_head->object.sha1), remote);
 cleanup:
@@ -565,10 +596,9 @@ static int git_merge_config(const char *k, const char *v, void *cb)
        else if (!strcmp(k, "merge.ff")) {
                int boolval = git_config_maybe_bool(k, v);
                if (0 <= boolval) {
-                       allow_fast_forward = boolval;
+                       fast_forward = boolval ? FF_ALLOW : FF_NO;
                } else if (v && !strcmp(v, "only")) {
-                       allow_fast_forward = 1;
-                       fast_forward_only = 1;
+                       fast_forward = FF_ONLY;
                } /* do not barf on values from future versions of git */
                return 0;
        } else if (!strcmp(k, "merge.defaulttoupstream")) {
@@ -627,60 +657,8 @@ static void write_tree_trivial(unsigned char *sha1)
                die(_("git write-tree failed to write a tree"));
 }
 
-static const char *merge_argument(struct commit *commit)
-{
-       if (commit)
-               return sha1_to_hex(commit->object.sha1);
-       else
-               return EMPTY_TREE_SHA1_HEX;
-}
-
-int try_merge_command(const char *strategy, size_t xopts_nr,
-                     const char **xopts, struct commit_list *common,
-                     const char *head_arg, struct commit_list *remotes)
-{
-       const char **args;
-       int i = 0, x = 0, ret;
-       struct commit_list *j;
-       struct strbuf buf = STRBUF_INIT;
-
-       args = xmalloc((4 + xopts_nr + commit_list_count(common) +
-                       commit_list_count(remotes)) * sizeof(char *));
-       strbuf_addf(&buf, "merge-%s", strategy);
-       args[i++] = buf.buf;
-       for (x = 0; x < xopts_nr; x++) {
-               char *s = xmalloc(strlen(xopts[x])+2+1);
-               strcpy(s, "--");
-               strcpy(s+2, xopts[x]);
-               args[i++] = s;
-       }
-       for (j = common; j; j = j->next)
-               args[i++] = xstrdup(merge_argument(j->item));
-       args[i++] = "--";
-       args[i++] = head_arg;
-       for (j = remotes; j; j = j->next)
-               args[i++] = xstrdup(merge_argument(j->item));
-       args[i] = NULL;
-       ret = run_command_v_opt(args, RUN_GIT_CMD);
-       strbuf_release(&buf);
-       i = 1;
-       for (x = 0; x < xopts_nr; x++)
-               free((void *)args[i++]);
-       for (j = common; j; j = j->next)
-               free((void *)args[i++]);
-       i += 2;
-       for (j = remotes; j; j = j->next)
-               free((void *)args[i++]);
-       free(args);
-       discard_cache();
-       if (read_cache() < 0)
-               die(_("failed to read the cache"));
-       resolve_undo_clear();
-
-       return ret;
-}
-
 static int try_merge_strategy(const char *strategy, struct commit_list *common,
+                             struct commit_list *remoteheads,
                              struct commit *head, const char *head_arg)
 {
        int index_fd;
@@ -760,56 +738,6 @@ static int count_unmerged_entries(void)
        return ret;
 }
 
-int checkout_fast_forward(const unsigned char *head, const unsigned char *remote)
-{
-       struct tree *trees[MAX_UNPACK_TREES];
-       struct unpack_trees_options opts;
-       struct tree_desc t[MAX_UNPACK_TREES];
-       int i, fd, nr_trees = 0;
-       struct dir_struct dir;
-       struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
-
-       refresh_cache(REFRESH_QUIET);
-
-       fd = hold_locked_index(lock_file, 1);
-
-       memset(&trees, 0, sizeof(trees));
-       memset(&opts, 0, sizeof(opts));
-       memset(&t, 0, sizeof(t));
-       if (overwrite_ignore) {
-               memset(&dir, 0, sizeof(dir));
-               dir.flags |= DIR_SHOW_IGNORED;
-               setup_standard_excludes(&dir);
-               opts.dir = &dir;
-       }
-
-       opts.head_idx = 1;
-       opts.src_index = &the_index;
-       opts.dst_index = &the_index;
-       opts.update = 1;
-       opts.verbose_update = 1;
-       opts.merge = 1;
-       opts.fn = twoway_merge;
-       setup_unpack_trees_porcelain(&opts, "merge");
-
-       trees[nr_trees] = parse_tree_indirect(head);
-       if (!trees[nr_trees++])
-               return -1;
-       trees[nr_trees] = parse_tree_indirect(remote);
-       if (!trees[nr_trees++])
-               return -1;
-       for (i = 0; i < nr_trees; i++) {
-               parse_tree(trees[i]);
-               init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
-       }
-       if (unpack_trees(nr_trees, t, &opts))
-               return -1;
-       if (write_cache(fd, active_cache, active_nr) ||
-               commit_locked_index(lock_file))
-               die(_("unable to write new index file"));
-       return 0;
-}
-
 static void split_merge_strategies(const char *string, struct strategy **list,
                                   int *nr, int *alloc)
 {
@@ -874,14 +802,14 @@ static void read_merge_msg(struct strbuf *msg)
                die_errno(_("Could not read from '%s'"), filename);
 }
 
-static void write_merge_state(void);
-static void abort_commit(const char *err_msg)
+static void write_merge_state(struct commit_list *);
+static void abort_commit(struct commit_list *remoteheads, const char *err_msg)
 {
        if (err_msg)
                error("%s", err_msg);
        fprintf(stderr,
                _("Not committing merge; use 'git commit' to complete the merge.\n"));
-       write_merge_state();
+       write_merge_state(remoteheads);
        exit(1);
 }
 
@@ -889,34 +817,34 @@ static const char merge_editor_comment[] =
 N_("Please enter a commit message to explain why this merge is necessary,\n"
    "especially if it merges an updated upstream into a topic branch.\n"
    "\n"
-   "Lines starting with '#' will be ignored, and an empty message aborts\n"
+   "Lines starting with '%c' will be ignored, and an empty message aborts\n"
    "the commit.\n");
 
-static void prepare_to_commit(void)
+static void prepare_to_commit(struct commit_list *remoteheads)
 {
        struct strbuf msg = STRBUF_INIT;
-       const char *comment = _(merge_editor_comment);
        strbuf_addbuf(&msg, &merge_msg);
        strbuf_addch(&msg, '\n');
        if (0 < option_edit)
-               strbuf_add_lines(&msg, "# ", comment, strlen(comment));
+               strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
        write_merge_msg(&msg);
-       run_hook(get_index_file(), "prepare-commit-msg",
-                git_path("MERGE_MSG"), "merge", NULL, NULL);
-       if (option_edit) {
+       if (run_hook(get_index_file(), "prepare-commit-msg",
+                    git_path("MERGE_MSG"), "merge", NULL, NULL))
+               abort_commit(remoteheads, NULL);
+       if (0 < option_edit) {
                if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
-                       abort_commit(NULL);
+                       abort_commit(remoteheads, NULL);
        }
        read_merge_msg(&msg);
-       stripspace(&msg, option_edit);
+       stripspace(&msg, 0 < option_edit);
        if (!msg.len)
-               abort_commit(_("Empty commit message."));
+               abort_commit(remoteheads, _("Empty commit message."));
        strbuf_release(&merge_msg);
        strbuf_addbuf(&merge_msg, &msg);
        strbuf_release(&msg);
 }
 
-static int merge_trivial(struct commit *head)
+static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 {
        unsigned char result_tree[20], result_commit[20];
        struct commit_list *parent = xmalloc(sizeof(*parent));
@@ -927,45 +855,37 @@ static int merge_trivial(struct commit *head)
        parent->next = xmalloc(sizeof(*parent->next));
        parent->next->item = remoteheads->item;
        parent->next->next = NULL;
-       prepare_to_commit();
+       prepare_to_commit(remoteheads);
        if (commit_tree(&merge_msg, result_tree, parent, result_commit, NULL,
                        sign_commit))
                die(_("failed to write commit object"));
-       finish(head, result_commit, "In-index merge");
+       finish(head, remoteheads, result_commit, "In-index merge");
        drop_save();
        return 0;
 }
 
 static int finish_automerge(struct commit *head,
+                           int head_subsumed,
                            struct commit_list *common,
+                           struct commit_list *remoteheads,
                            unsigned char *result_tree,
                            const char *wt_strategy)
 {
-       struct commit_list *parents = NULL, *j;
+       struct commit_list *parents = NULL;
        struct strbuf buf = STRBUF_INIT;
        unsigned char result_commit[20];
 
        free_commit_list(common);
-       if (allow_fast_forward) {
-               parents = remoteheads;
+       parents = remoteheads;
+       if (!head_subsumed || fast_forward == FF_NO)
                commit_list_insert(head, &parents);
-               parents = reduce_heads(parents);
-       } else {
-               struct commit_list **pptr = &parents;
-
-               pptr = &commit_list_insert(head,
-                               pptr)->next;
-               for (j = remoteheads; j; j = j->next)
-                       pptr = &commit_list_insert(j->item, pptr)->next;
-       }
        strbuf_addch(&merge_msg, '\n');
-       prepare_to_commit();
-       free_commit_list(remoteheads);
+       prepare_to_commit(remoteheads);
        if (commit_tree(&merge_msg, result_tree, parents, result_commit,
                        NULL, sign_commit))
                die(_("failed to write commit object"));
        strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
-       finish(head, result_commit, buf.buf);
+       finish(head, remoteheads, result_commit, buf.buf);
        strbuf_release(&buf);
        drop_save();
        return 0;
@@ -983,7 +903,7 @@ static int suggest_conflicts(int renormalizing)
                die_errno(_("Could not open '%s' for writing"), filename);
        fprintf(fp, "\nConflicts:\n");
        for (pos = 0; pos < active_nr; pos++) {
-               struct cache_entry *ce = active_cache[pos];
+               const struct cache_entry *ce = active_cache[pos];
 
                if (ce_stage(ce)) {
                        fprintf(fp, "\t%s\n", ce->name);
@@ -1042,7 +962,7 @@ static int evaluate_result(void)
 }
 
 /*
- * Pretend as if the user told us to merge with the tracking
+ * Pretend as if the user told us to merge with the remote-tracking
  * branch we have for the upstream of the current branch
  */
 static int setup_with_upstream(const char ***argv)
@@ -1061,7 +981,7 @@ static int setup_with_upstream(const char ***argv)
        args = xcalloc(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"),
+                       die(_("No remote-tracking branch for %s from %s"),
                            branch->merge[i]->src, branch->remote_name);
                args[i] = branch->merge[i]->dst;
        }
@@ -1070,7 +990,7 @@ static int setup_with_upstream(const char ***argv)
        return i;
 }
 
-static void write_merge_state(void)
+static void write_merge_state(struct commit_list *remoteheads)
 {
        const char *filename;
        int fd;
@@ -1102,13 +1022,74 @@ static void write_merge_state(void)
        if (fd < 0)
                die_errno(_("Could not open '%s' for writing"), filename);
        strbuf_reset(&buf);
-       if (!allow_fast_forward)
+       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);
 }
 
+static int default_edit_option(void)
+{
+       static const char name[] = "GIT_MERGE_AUTOEDIT";
+       const char *e = getenv(name);
+       struct stat st_stdin, st_stdout;
+
+       if (have_message)
+               /* an explicit -m msg without --[no-]edit */
+               return 0;
+
+       if (e) {
+               int v = git_config_maybe_bool(name, e);
+               if (v < 0)
+                       die("Bad value '%s' in environment '%s'", e, name);
+               return v;
+       }
+
+       /* Use editor if stdin and stdout are the same and is a tty */
+       return (!fstat(0, &st_stdin) &&
+               !fstat(1, &st_stdout) &&
+               isatty(0) && isatty(1) &&
+               st_stdin.st_dev == st_stdout.st_dev &&
+               st_stdin.st_ino == st_stdout.st_ino &&
+               st_stdin.st_mode == st_stdout.st_mode);
+}
+
+static struct commit_list *collect_parents(struct commit *head_commit,
+                                          int *head_subsumed,
+                                          int argc, const char **argv)
+{
+       int i;
+       struct commit_list *remoteheads = NULL, *parents, *next;
+       struct commit_list **remotes = &remoteheads;
+
+       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
+                       remotes = &commit_list_insert(commit, remotes)->next;
+       }
+       return remoteheads;
+}
+
 int cmd_merge(int argc, const char **argv, const char *prefix)
 {
        unsigned char result_tree[20];
@@ -1117,11 +1098,11 @@ 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;
+       int flag, 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;
-       struct commit_list **remotes = &remoteheads;
+       struct commit_list *remoteheads, *p;
        void *branch_to_free;
 
        if (argc == 2 && !strcmp(argv[1], "-h"))
@@ -1190,14 +1171,11 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                show_diffstat = 0;
 
        if (squash) {
-               if (!allow_fast_forward)
+               if (fast_forward == FF_NO)
                        die(_("You cannot combine --squash with --no-ff."));
                option_commit = 0;
        }
 
-       if (!allow_fast_forward && fast_forward_only)
-               die(_("You cannot combine --no-ff with --ff-only."));
-
        if (!abort_current_merge) {
                if (!argc) {
                        if (default_to_upstream)
@@ -1226,6 +1204,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                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;
                /*
@@ -1238,10 +1217,11 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                                "empty head"));
                if (squash)
                        die(_("Squash commit into empty head not supported yet"));
-               if (!allow_fast_forward)
+               if (fast_forward == FF_NO)
                        die(_("Non-fast-forward commit does not make sense into "
                            "an empty head"));
-               remote_head = get_merge_parent(argv[0]);
+               remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
+               remote_head = remoteheads->item;
                if (!remote_head)
                        die(_("%s - not something we can merge"), argv[0]);
                read_empty(remote_head->object.sha1, 0);
@@ -1259,14 +1239,16 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                 * the standard merge summary message to be appended
                 * to the given message.
                 */
-               for (i = 0; i < argc; i++)
-                       merge_name(argv[i], &merge_names);
+               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)
@@ -1278,36 +1260,65 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                usage_with_options(builtin_merge_usage,
                        builtin_merge_options);
 
+       if (verify_signatures) {
+               for (p = remoteheads; p; p = p->next) {
+                       struct commit *commit = p->item;
+                       char hex[41];
+                       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));
+                       switch (signature_check.result) {
+                       case 'G':
+                               break;
+                       case 'U':
+                               die(_("Commit %s has an untrusted GPG signature, "
+                                     "allegedly by %s."), hex, signature_check.signer);
+                       case 'B':
+                               die(_("Commit %s has a bad GPG signature "
+                                     "allegedly by %s."), hex, signature_check.signer);
+                       default: /* 'N' */
+                               die(_("Commit %s does not have a GPG signature."), hex);
+                       }
+                       if (verbosity >= 0 && signature_check.result == 'G')
+                               printf(_("Commit %s has a good GPG signature by %s\n"),
+                                      hex, signature_check.signer);
+
+                       free(signature_check.gpg_output);
+                       free(signature_check.gpg_status);
+                       free(signature_check.signer);
+                       free(signature_check.key);
+               }
+       }
+
        strbuf_addstr(&buf, "merge");
-       for (i = 0; i < argc; i++)
-               strbuf_addf(&buf, " %s", argv[i]);
+       for (p = remoteheads; p; p = p->next)
+               strbuf_addf(&buf, " %s", merge_remote_util(p->item)->name);
        setenv("GIT_REFLOG_ACTION", buf.buf, 0);
        strbuf_reset(&buf);
 
-       for (i = 0; i < argc; i++) {
-               struct commit *commit = get_merge_parent(argv[i]);
-               if (!commit)
-                       die(_("%s - not something we can merge"), argv[i]);
-               remotes = &commit_list_insert(commit, remotes)->next;
+       for (p = remoteheads; p; p = p->next) {
+               struct commit *commit = p->item;
                strbuf_addf(&buf, "GITHEAD_%s",
                            sha1_to_hex(commit->object.sha1));
-               setenv(buf.buf, argv[i], 1);
+               setenv(buf.buf, merge_remote_util(commit)->name, 1);
                strbuf_reset(&buf);
-               if (!fast_forward_only &&
+               if (fast_forward != FF_ONLY &&
                    merge_remote_util(commit) &&
                    merge_remote_util(commit)->obj &&
-                   merge_remote_util(commit)->obj->type == OBJ_TAG) {
-                       if (option_edit < 0)
-                               option_edit = 1;
-                       allow_fast_forward = 0;
-               }
+                   merge_remote_util(commit)->obj->type == OBJ_TAG)
+                       fast_forward = FF_NO;
        }
 
        if (option_edit < 0)
-               option_edit = 0;
+               option_edit = default_edit_option();
 
        if (!use_strategies) {
-               if (!remoteheads->next)
+               if (!remoteheads)
+                       ; /* already up-to-date */
+               else if (!remoteheads->next)
                        add_strategies(pull_twohead, DEFAULT_TWOHEAD);
                else
                        add_strategies(pull_octopus, DEFAULT_OCTOPUS);
@@ -1315,12 +1326,14 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 
        for (i = 0; i < use_strategies_nr; i++) {
                if (use_strategies[i]->attr & NO_FAST_FORWARD)
-                       allow_fast_forward = 0;
+                       fast_forward = FF_NO;
                if (use_strategies[i]->attr & NO_TRIVIAL)
                        allow_trivial = 0;
        }
 
-       if (!remoteheads->next)
+       if (!remoteheads)
+               ; /* already up-to-date */
+       else if (!remoteheads->next)
                common = get_merge_bases(head_commit, remoteheads->item, 1);
        else {
                struct commit_list *list = remoteheads;
@@ -1332,17 +1345,18 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
                   NULL, 0, DIE_ON_ERR);
 
-       if (!common)
+       if (remoteheads && !common)
                ; /* No common ancestors found. We need a real merge. */
-       else if (!remoteheads->next && !common->next &&
-                       common->item == remoteheads->item) {
+       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.");
                goto done;
-       } else if (allow_fast_forward && !remoteheads->next &&
+       } else if (fast_forward != FF_NO && !remoteheads->next &&
                        !common->next &&
                        !hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
                /* Again the most common case of merging one remote. */
@@ -1368,12 +1382,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                }
 
                if (checkout_fast_forward(head_commit->object.sha1,
-                                         commit->object.sha1)) {
+                                         commit->object.sha1,
+                                         overwrite_ignore)) {
                        ret = 1;
                        goto done;
                }
 
-               finish(head_commit, commit->object.sha1, msg.buf);
+               finish(head_commit, remoteheads, commit->object.sha1, msg.buf);
                drop_save();
                goto done;
        } else if (!remoteheads->next && common->next)
@@ -1388,14 +1403,14 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                 * only one common.
                 */
                refresh_cache(REFRESH_QUIET);
-               if (allow_trivial && !fast_forward_only) {
+               if (allow_trivial && fast_forward != FF_ONLY) {
                        /* See if it is really trivial. */
-                       git_committer_info(IDENT_ERROR_ON_NO_NAME);
+                       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)) {
-                               ret = merge_trivial(head_commit);
+                               ret = merge_trivial(head_commit, remoteheads);
                                goto done;
                        }
                        printf(_("Nope.\n"));
@@ -1429,11 +1444,11 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                }
        }
 
-       if (fast_forward_only)
+       if (fast_forward == FF_ONLY)
                die(_("Not possible to fast-forward, aborting."));
 
        /* We are going to make a new commit. */
-       git_committer_info(IDENT_ERROR_ON_NO_NAME);
+       git_committer_info(IDENT_STRICT);
 
        /*
         * At this point, we need a real merge.  No matter what strategy
@@ -1466,7 +1481,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                wt_strategy = use_strategies[i]->name;
 
                ret = try_merge_strategy(use_strategies[i]->name,
-                                        common, head_commit, head_arg);
+                                        common, remoteheads,
+                                        head_commit, head_arg);
                if (!option_commit && !ret) {
                        merge_was_ok = 1;
                        /*
@@ -1508,8 +1524,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
         * auto resolved the merge cleanly.
         */
        if (automerge_was_ok) {
-               ret = finish_automerge(head_commit, common, result_tree,
-                                      wt_strategy);
+               ret = finish_automerge(head_commit, head_subsumed,
+                                      common, remoteheads,
+                                      result_tree, wt_strategy);
                goto done;
        }
 
@@ -1534,13 +1551,14 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
                restore_state(head_commit->object.sha1, stash);
                printf(_("Using the %s to prepare resolving by hand.\n"),
                        best_strategy);
-               try_merge_strategy(best_strategy, common, head_commit, head_arg);
+               try_merge_strategy(best_strategy, common, remoteheads,
+                                  head_commit, head_arg);
        }
 
        if (squash)
-               finish(head_commit, NULL, NULL);
+               finish(head_commit, remoteheads, NULL, NULL);
        else
-               write_merge_state();
+               write_merge_state(remoteheads);
 
        if (merge_was_ok)
                fprintf(stderr, _("Automatic merge went well; "