1 files changed, 350 insertions, 280 deletions

diff --git a/builtin/merge.c b/builtin/merge.c
index e066bf1b0b..34a6166b52 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -26,6 +26,8 @@
 #include "merge-recursive.h"
 #include "resolve-undo.h"
 #include "remote.h"
+#include "fmt-merge-msg.h"
+#include "gpg-interface.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)
@@ -38,18 +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, squash;
-static int option_commit = 1, allow_fast_forward = 1;
-static int fast_forward_only, option_edit;
-static int allow_trivial = 1, have_message;
-static struct strbuf merge_msg;
-static struct commit_list *remoteheads;
+static int show_diffstat = 1, shortlog_len = -1, squash;
+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 strategy **use_strategies;
 static size_t use_strategies_nr, use_strategies_alloc;
 static const char **xopts;
@@ -62,6 +64,7 @@ static int allow_rerere_auto;
 static int abort_current_merge;
 static int show_progress = -1;
 static int default_to_upstream;
+static const char *sign_commit;
 
 static struct strategy all_strategy[] = {
 	{ "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
@@ -73,6 +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)
 {
@@ -175,38 +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)"),
-	OPT_BOOLEAN('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_("perform a commit if the merge succeeds (default)")),
+	OPT_BOOL('e', "edit", &option_edit,
+		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),
+		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()
 };
 
@@ -311,7 +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;
@@ -359,6 +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;
@@ -373,7 +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"));
@@ -392,11 +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);
@@ -408,21 +433,11 @@ static void finish(struct commit *head_commit,
 	strbuf_release(&reflog_message);
 }
 
-static struct object *want_commit(const char *name)
-{
-	struct object *obj;
-	unsigned char sha1[20];
-	if (get_sha1(name, sha1))
-		return NULL;
-	obj = parse_object(sha1);
-	return peel_to_type(name, 0, obj, OBJ_COMMIT);
-}
-
 /* Get the name for the merge commit's message. */
 static void merge_name(const char *remote, struct strbuf *msg)
 {
-	struct object *remote_head;
-	unsigned char branch_head[20], buf_sha[20];
+	struct commit *remote_head;
+	unsigned char branch_head[20];
 	struct strbuf buf = STRBUF_INIT;
 	struct strbuf bname = STRBUF_INIT;
 	const char *ptr;
@@ -433,7 +448,7 @@ static void merge_name(const char *remote, struct strbuf *msg)
 	remote = bname.buf;
 
 	memset(branch_head, 0, sizeof(branch_head));
-	remote_head = want_commit(remote);
+	remote_head = get_merge_parent(remote);
 	if (!remote_head)
 		die(_("'%s' does not point to a commit"), remote);
 
@@ -443,6 +458,11 @@ static void merge_name(const char *remote, struct strbuf *msg)
 				    sha1_to_hex(branch_head), remote);
 			goto cleanup;
 		}
+		if (!prefixcmp(found_ref, "refs/tags/")) {
+			strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
+				    sha1_to_hex(branch_head), remote);
+			goto cleanup;
+		}
 		if (!prefixcmp(found_ref, "refs/remotes/")) {
 			strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 				    sha1_to_hex(branch_head), remote);
@@ -481,10 +501,10 @@ static void merge_name(const char *remote, struct strbuf *msg)
 		strbuf_addstr(&truname, "refs/heads/");
 		strbuf_addstr(&truname, remote);
 		strbuf_setlen(&truname, truname.len - len);
-		if (resolve_ref(truname.buf, buf_sha, 1, NULL)) {
+		if (ref_exists(truname.buf)) {
 			strbuf_addf(msg,
 				    "%s\t\tbranch '%s'%s of .\n",
-				    sha1_to_hex(remote_head->sha1),
+				    sha1_to_hex(remote_head->object.sha1),
 				    truname.buf + 11,
 				    (early ? " (early part)" : ""));
 			strbuf_release(&truname);
@@ -513,8 +533,21 @@ 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->sha1), remote);
+		sha1_to_hex(remote_head->object.sha1), remote);
 cleanup:
 	strbuf_release(&buf);
 	strbuf_release(&bname);
@@ -542,6 +575,8 @@ static void parse_branch_merge_options(char *bmo)
 
 static int git_merge_config(const char *k, const char *v, void *cb)
 {
+	int status;
+
 	if (branch && !prefixcmp(k, "branch.") &&
 		!prefixcmp(k + 7, branch) &&
 		!strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
@@ -558,27 +593,25 @@ static int git_merge_config(const char *k, const char *v, void *cb)
 		return git_config_string(&pull_octopus, k, v);
 	else if (!strcmp(k, "merge.renormalize"))
 		option_renormalize = git_config_bool(k, v);
-	else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary")) {
-		int is_bool;
-		shortlog_len = git_config_bool_or_int(k, v, &is_bool);
-		if (!is_bool && shortlog_len < 0)
-			return error(_("%s: negative length %s"), k, v);
-		if (is_bool && shortlog_len)
-			shortlog_len = DEFAULT_MERGE_LOG_LEN;
-		return 0;
-	} else if (!strcmp(k, "merge.ff")) {
+	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")) {
 		default_to_upstream = git_config_bool(k, v);
 		return 0;
 	}
+
+	status = fmt_merge_msg_config(k, v, cb);
+	if (status)
+		return status;
+	status = git_gpg_config(k, v, NULL);
+	if (status)
+		return status;
 	return git_diff_ui_config(k, v, cb);
 }
 
@@ -624,60 +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;
@@ -718,7 +699,7 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 				die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 
 		o.branch1 = head_arg;
-		o.branch2 = remoteheads->item->util;
+		o.branch2 = merge_remote_util(remoteheads->item)->name;
 
 		for (j = common; j; j = j->next)
 			commit_list_insert(j->item, &reversed);
@@ -757,54 +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));
-	memset(&dir, 0, sizeof(dir));
-	dir.flags |= DIR_SHOW_IGNORED;
-	dir.exclude_per_dir = ".gitignore";
-	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)
 {
@@ -869,39 +802,49 @@ 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);
 }
 
-static void prepare_to_commit(void)
+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 '%c' will be ignored, and an empty message aborts\n"
+   "the commit.\n");
+
+static void prepare_to_commit(struct commit_list *remoteheads)
 {
 	struct strbuf msg = STRBUF_INIT;
 	strbuf_addbuf(&msg, &merge_msg);
 	strbuf_addch(&msg, '\n');
+	if (0 < option_edit)
+		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));
@@ -912,43 +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();
-	if (commit_tree(&merge_msg, result_tree, parent, result_commit, NULL))
+	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);
-	if (commit_tree(&merge_msg, result_tree, parents, result_commit, NULL))
+	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;
@@ -966,7 +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);
@@ -1025,7 +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)
@@ -1044,7 +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;
 	}
@@ -1053,16 +990,23 @@ 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;
 	struct commit_list *j;
 	struct strbuf buf = STRBUF_INIT;
 
-	for (j = remoteheads; j; j = j->next)
-		strbuf_addf(&buf, "%s\n",
-			sha1_to_hex(j->item->object.sha1));
+	for (j = remoteheads; j; j = j->next) {
+		unsigned const char *sha1;
+		struct commit *c = j->item;
+		if (c->util && merge_remote_util(c)->obj) {
+			sha1 = merge_remote_util(c)->obj->sha1;
+		} else {
+			sha1 = c->object.sha1;
+		}
+		strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
+	}
 	filename = git_path("MERGE_HEAD");
 	fd = open(filename, O_WRONLY | O_CREAT, 0666);
 	if (fd < 0)
@@ -1078,13 +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];
@@ -1093,11 +1098,12 @@ 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;
+	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"))
 		usage_with_options(builtin_merge_usage, builtin_merge_options);
@@ -1106,7 +1112,7 @@ 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 = resolve_ref("HEAD", head_sha1, 0, &flag);
+	branch = branch_to_free = resolve_refdup("HEAD", head_sha1, 0, &flag);
 	if (branch && !prefixcmp(branch, "refs/heads/"))
 		branch += 11;
 	if (!branch || is_null_sha1(head_sha1))
@@ -1120,6 +1126,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		parse_branch_merge_options(branch_mergeoptions);
 	argc = parse_options(argc, argv, prefix, builtin_merge_options,
 			builtin_merge_usage, 0);
+	if (shortlog_len < 0)
+		shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
 
 	if (verbosity < 0 && show_progress == -1)
 		show_progress = 0;
@@ -1132,7 +1140,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			die(_("There is no merge to abort (MERGE_HEAD missing)."));
 
 		/* Invoke 'git reset --merge' */
-		return cmd_reset(nargc, nargv, prefix);
+		ret = cmd_reset(nargc, nargv, prefix);
+		goto done;
 	}
 
 	if (read_cache_unmerged())
@@ -1162,18 +1171,18 @@ 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 && default_to_upstream)
-			argc = setup_with_upstream(&argv);
-		else if (argc == 1 && !strcmp(argv[0], "-"))
+		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)
@@ -1195,8 +1204,9 @@ 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 object *remote_head;
+		struct commit *remote_head;
 		/*
 		 * If the merged head is a valid one there is no reason
 		 * to forbid "git merge" into a branch yet to be born.
@@ -1207,16 +1217,17 @@ 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 = want_commit(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->sha1, 0);
-		update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
-				DIE_ON_ERR);
-		return 0;
+		read_empty(remote_head->object.sha1, 0);
+		update_ref("initial pull", "HEAD", remote_head->object.sha1,
+			   NULL, 0, DIE_ON_ERR);
+		goto done;
 	} else {
 		struct strbuf merge_names = STRBUF_INIT;
 
@@ -1224,19 +1235,22 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		head_arg = "HEAD";
 
 		/*
-		 * All the rest are the commits being merged;
-		 * prepare the standard merge summary message to
-		 * be appended to the given message.  If remote
-		 * is invalid we will die later in the common
-		 * codepath so we discard the error in this
-		 * loop.
+		 * All the rest are the commits being merged; prepare
+		 * 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) {
-			fmt_merge_msg(&merge_names, &merge_msg, !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);
 		}
@@ -1246,30 +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 object *o;
-		struct commit *commit;
-
-		o = want_commit(argv[i]);
-		if (!o)
-			die(_("%s - not something we can merge"), argv[i]);
-		commit = lookup_commit(o->sha1);
-		commit->util = (void *)argv[i];
-		remotes = &commit_list_insert(commit, remotes)->next;
-
-		strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
-		setenv(buf.buf, argv[i], 1);
+	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, merge_remote_util(commit)->name, 1);
 		strbuf_reset(&buf);
+		if (fast_forward != FF_ONLY &&
+		    merge_remote_util(commit) &&
+		    merge_remote_util(commit)->obj &&
+		    merge_remote_util(commit)->obj->type == OBJ_TAG)
+			fast_forward = FF_NO;
 	}
 
+	if (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);
@@ -1277,12 +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;
@@ -1294,22 +1345,23 @@ 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.");
-		return 0;
-	} else if (allow_fast_forward && !remoteheads->next &&
+		goto done;
+	} 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. */
 		struct strbuf msg = STRBUF_INIT;
-		struct object *o;
+		struct commit *commit;
 		char hex[41];
 
 		strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));
@@ -1323,16 +1375,22 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		if (have_message)
 			strbuf_addstr(&msg,
 				" (no commit created; -m option ignored)");
-		o = want_commit(sha1_to_hex(remoteheads->item->object.sha1));
-		if (!o)
-			return 1;
+		commit = remoteheads->item;
+		if (!commit) {
+			ret = 1;
+			goto done;
+		}
 
-		if (checkout_fast_forward(head_commit->object.sha1, remoteheads->item->object.sha1))
-			return 1;
+		if (checkout_fast_forward(head_commit->object.sha1,
+					  commit->object.sha1,
+					  overwrite_ignore)) {
+			ret = 1;
+			goto done;
+		}
 
-		finish(head_commit, o->sha1, msg.buf);
+		finish(head_commit, remoteheads, commit->object.sha1, msg.buf);
 		drop_save();
-		return 0;
+		goto done;
 	} else if (!remoteheads->next && common->next)
 		;
 		/*
@@ -1345,13 +1403,16 @@ 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))
-				return merge_trivial(head_commit);
+					       head_commit->object.sha1,
+					       remoteheads->item->object.sha1)) {
+				ret = merge_trivial(head_commit, remoteheads);
+				goto done;
+			}
 			printf(_("Nope.\n"));
 		}
 	} else {
@@ -1379,15 +1440,15 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		}
 		if (up_to_date) {
 			finish_up_to_date("Already up-to-date. Yeeah!");
-			return 0;
+			goto done;
 		}
 	}
 
-	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
@@ -1420,7 +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;
 			/*
@@ -1461,9 +1523,12 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	 * If we have a resulting tree, that means the strategy module
 	 * auto resolved the merge cleanly.
 	 */
-	if (automerge_was_ok)
-		return finish_automerge(head_commit, common, result_tree,
-					wt_strategy);
+	if (automerge_was_ok) {
+		ret = finish_automerge(head_commit, head_subsumed,
+				       common, remoteheads,
+				       result_tree, wt_strategy);
+		goto done;
+	}
 
 	/*
 	 * Pick the result from the best strategy and have the user fix
@@ -1477,7 +1542,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		else
 			fprintf(stderr, _("Merge with strategy %s failed.\n"),
 				use_strategies[0]->name);
-		return 2;
+		ret = 2;
+		goto done;
 	} else if (best_strategy == wt_strategy)
 		; /* We already have its result in the working tree. */
 	else {
@@ -1485,18 +1551,22 @@ 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) {
+	if (merge_was_ok)
 		fprintf(stderr, _("Automatic merge went well; "
 			"stopped before committing as requested\n"));
-		return 0;
-	} else
-		return suggest_conflicts(option_renormalize);
+	else
+		ret = suggest_conflicts(option_renormalize);
+
+done:
+	free(branch_to_free);
+	return ret;
 }