32 files changed, 293 insertions, 247 deletions

diff --git a/builtin/am.c b/builtin/am.c
index c973bd96dc..ff0869d46f 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -431,6 +431,14 @@ static void am_load(struct am_state *state)
 	read_state_file(&sb, state, "utf8", 1);
 	state->utf8 = !strcmp(sb.buf, "t");
 
+	if (file_exists(am_path(state, "rerere-autoupdate"))) {
+		read_state_file(&sb, state, "rerere-autoupdate", 1);
+		state->allow_rerere_autoupdate = strcmp(sb.buf, "t") ?
+			RERERE_NOAUTOUPDATE : RERERE_AUTOUPDATE;
+	} else {
+		state->allow_rerere_autoupdate = 0;
+	}
+
 	read_state_file(&sb, state, "keep", 1);
 	if (!strcmp(sb.buf, "t"))
 		state->keep = KEEP_TRUE;
@@ -1003,6 +1011,10 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
 	write_state_bool(state, "sign", state->signoff);
 	write_state_bool(state, "utf8", state->utf8);
 
+	if (state->allow_rerere_autoupdate)
+		write_state_bool(state, "rerere-autoupdate",
+			 state->allow_rerere_autoupdate == RERERE_AUTOUPDATE);
+
 	switch (state->keep) {
 	case KEEP_FALSE:
 		str = "f";
@@ -1131,7 +1143,7 @@ static int index_has_changes(struct strbuf *sb)
 	struct object_id head;
 	int i;
 
-	if (!get_sha1_tree("HEAD", head.hash)) {
+	if (!get_oid_tree("HEAD", &head)) {
 		struct diff_options opt;
 
 		diff_setup(&opt);
@@ -1432,7 +1444,7 @@ static void write_index_patch(const struct am_state *state)
 	struct rev_info rev_info;
 	FILE *fp;
 
-	if (!get_sha1_tree("HEAD", head.hash))
+	if (!get_oid_tree("HEAD", &head))
 		tree = lookup_tree(&head);
 	else
 		tree = lookup_tree(&empty_tree_oid);
@@ -1661,7 +1673,7 @@ static void do_commit(const struct am_state *state)
 	if (write_cache_as_tree(tree.hash, 0, NULL))
 		die(_("git write-tree failed to write a tree"));
 
-	if (!get_sha1_commit("HEAD", parent.hash)) {
+	if (!get_oid_commit("HEAD", &parent)) {
 		old_oid = &parent;
 		commit_list_insert(lookup_commit(&parent), &parents);
 	} else {
diff --git a/builtin/branch.c b/builtin/branch.c
index 8a0595e115..16d391b407 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -92,7 +92,7 @@ static int git_branch_config(const char *var, const char *value, void *cb)
 			return config_error_nonbool(var);
 		return color_parse(value, branch_colors[slot]);
 	}
-	return git_color_default_config(var, value, cb);
+	return git_default_config(var, value, cb);
 }
 
 static const char *branch_get_color(enum color_branch ix)
@@ -383,7 +383,7 @@ static char *build_format(struct ref_filter *filter, int maxwidth, const char *r
 	return strbuf_detach(&fmt, NULL);
 }
 
-static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sorting, const char *format)
+static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sorting, struct ref_format *format)
 {
 	int i;
 	struct ref_array array;
@@ -407,14 +407,17 @@ static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sortin
 	if (filter->verbose)
 		maxwidth = calc_maxwidth(&array, strlen(remote_prefix));
 
-	if (!format)
-		format = to_free = build_format(filter, maxwidth, remote_prefix);
-	verify_ref_format(format);
+	if (!format->format)
+		format->format = to_free = build_format(filter, maxwidth, remote_prefix);
+	format->use_color = branch_use_color;
+
+	if (verify_ref_format(format))
+		die(_("unable to parse format string"));
 
 	ref_array_sort(sorting, &array);
 
 	for (i = 0; i < array.nr; i++) {
-		format_ref_array_item(array.items[i], format, 0, &out);
+		format_ref_array_item(array.items[i], format, &out);
 		if (column_active(colopts)) {
 			assert(!filter->verbose && "--column and --verbose are incompatible");
 			 /* format to a string_list to let print_columns() do its job */
@@ -549,7 +552,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 	struct ref_filter filter;
 	int icase = 0;
 	static struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
-	const char *format = NULL;
+	struct ref_format format = REF_FORMAT_INIT;
 
 	struct option options[] = {
 		OPT_GROUP(N_("Generic options")),
@@ -593,7 +596,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 			N_("print only branches of the object"), 0, parse_opt_object_name
 		},
 		OPT_BOOL('i', "ignore-case", &icase, N_("sorting and filtering are case insensitive")),
-		OPT_STRING(  0 , "format", &format, N_("format"), N_("format to use for the output")),
+		OPT_STRING(  0 , "format", &format.format, N_("format"), N_("format to use for the output")),
 		OPT_END(),
 	};
 
@@ -667,7 +670,7 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 		if (!sorting)
 			sorting = ref_default_sorting();
 		sorting->ignore_case = icase;
-		print_ref_list(&filter, sorting, format);
+		print_ref_list(&filter, sorting, &format);
 		print_columns(&output, colopts, NULL);
 		string_list_clear(&output, 0);
 		return 0;
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index 96b786e489..62c8cf0ebf 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -63,8 +63,8 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name,
 	if (unknown_type)
 		flags |= OBJECT_INFO_ALLOW_UNKNOWN_TYPE;
 
-	if (get_sha1_with_context(obj_name, GET_SHA1_RECORD_PATH,
-				  oid.hash, &obj_context))
+	if (get_oid_with_context(obj_name, GET_OID_RECORD_PATH,
+				 &oid, &obj_context))
 		die("Not a valid object name %s", obj_name);
 
 	if (!path)
@@ -361,10 +361,10 @@ static void batch_one_object(const char *obj_name, struct batch_options *opt,
 			     struct expand_data *data)
 {
 	struct object_context ctx;
-	int flags = opt->follow_symlinks ? GET_SHA1_FOLLOW_SYMLINKS : 0;
+	int flags = opt->follow_symlinks ? GET_OID_FOLLOW_SYMLINKS : 0;
 	enum follow_symlinks_result result;
 
-	result = get_sha1_with_context(obj_name, flags, data->oid.hash, &ctx);
+	result = get_oid_with_context(obj_name, flags, &data->oid, &ctx);
 	if (result != FOUND) {
 		switch (result) {
 		case MISSING_OBJECT:
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 9661e1bcba..2d75ac66c7 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -358,6 +358,8 @@ static int checkout_paths(const struct checkout_opts *opts,
 	state.force = 1;
 	state.refresh_cache = 1;
 	state.istate = &the_index;
+
+	enable_delayed_checkout(&state);
 	for (pos = 0; pos < active_nr; pos++) {
 		struct cache_entry *ce = active_cache[pos];
 		if (ce->ce_flags & CE_MATCHED) {
@@ -372,6 +374,7 @@ static int checkout_paths(const struct checkout_opts *opts,
 			pos = skip_same_name(ce, pos) - 1;
 		}
 	}
+	errs |= finish_delayed_checkout(&state);
 
 	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 		die(_("unable to write new index file"));
diff --git a/builtin/clean.c b/builtin/clean.c
index 057fc97fe4..21a7a32994 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -33,15 +33,6 @@ static const char *msg_skip_git_dir = N_("Skipping repository %s\n");
 static const char *msg_would_skip_git_dir = N_("Would skip repository %s\n");
 static const char *msg_warn_remove_failed = N_("failed to remove %s");
 
-static int clean_use_color = -1;
-static char clean_colors[][COLOR_MAXLEN] = {
-	GIT_COLOR_RESET,
-	GIT_COLOR_NORMAL,	/* PLAIN */
-	GIT_COLOR_BOLD_BLUE,	/* PROMPT */
-	GIT_COLOR_BOLD,		/* HEADER */
-	GIT_COLOR_BOLD_RED,	/* HELP */
-	GIT_COLOR_BOLD_RED,	/* ERROR */
-};
 enum color_clean {
 	CLEAN_COLOR_RESET = 0,
 	CLEAN_COLOR_PLAIN = 1,
@@ -51,6 +42,16 @@ enum color_clean {
 	CLEAN_COLOR_ERROR = 5
 };
 
+static int clean_use_color = -1;
+static char clean_colors[][COLOR_MAXLEN] = {
+	[CLEAN_COLOR_ERROR] = GIT_COLOR_BOLD_RED,
+	[CLEAN_COLOR_HEADER] = GIT_COLOR_BOLD,
+	[CLEAN_COLOR_HELP] = GIT_COLOR_BOLD_RED,
+	[CLEAN_COLOR_PLAIN] = GIT_COLOR_NORMAL,
+	[CLEAN_COLOR_PROMPT] = GIT_COLOR_BOLD_BLUE,
+	[CLEAN_COLOR_RESET] = GIT_COLOR_RESET,
+};
+
 #define MENU_OPTS_SINGLETON		01
 #define MENU_OPTS_IMMEDIATE		02
 #define MENU_OPTS_LIST_ONLY		04
@@ -125,8 +126,7 @@ static int git_clean_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
-	/* inspect the color.ui config variable and others */
-	return git_color_default_config(var, value, cb);
+	return git_default_config(var, value, cb);
 }
 
 static const char *clean_get_color(enum color_clean ix)
diff --git a/builtin/commit-tree.c b/builtin/commit-tree.c
index a4a923d7c0..19e898fa4e 100644
--- a/builtin/commit-tree.c
+++ b/builtin/commit-tree.c
@@ -56,7 +56,7 @@ int cmd_commit_tree(int argc, const char **argv, const char *prefix)
 			struct object_id oid;
 			if (argc <= ++i)
 				usage(commit_tree_usage);
-			if (get_sha1_commit(argv[i], oid.hash))
+			if (get_oid_commit(argv[i], &oid))
 				die("Not a valid object name %s", argv[i]);
 			assert_sha1_type(oid.hash, OBJ_COMMIT);
 			new_parent(lookup_commit(&oid), &parents);
@@ -106,7 +106,7 @@ int cmd_commit_tree(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 
-		if (get_sha1_tree(arg, tree_oid.hash))
+		if (get_oid_tree(arg, &tree_oid))
 			die("Not a valid object name %s", arg);
 		if (got_tree)
 			die("Cannot give more than one trees");
diff --git a/builtin/commit.c b/builtin/commit.c
index 8e93802511..e7a2cb6285 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -510,7 +510,7 @@ static int run_status(FILE *fp, const char *index_file, const char *prefix, int
 	s->index_file = index_file;
 	s->fp = fp;
 	s->nowarn = nowarn;
-	s->is_initial = get_sha1(s->reference, oid.hash) ? 1 : 0;
+	s->is_initial = get_oid(s->reference, &oid) ? 1 : 0;
 	if (!s->is_initial)
 		hashcpy(s->sha1_commit, oid.hash);
 	s->status_format = status_format;
@@ -891,7 +891,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		if (amend)
 			parent = "HEAD^1";
 
-		if (get_sha1(parent, oid.hash)) {
+		if (get_oid(parent, &oid)) {
 			int i, ita_nr = 0;
 
 			for (i = 0; i < active_nr; i++)
@@ -1387,7 +1387,7 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 
 	fd = hold_locked_index(&index_lock, 0);
 
-	s.is_initial = get_sha1(s.reference, oid.hash) ? 1 : 0;
+	s.is_initial = get_oid(s.reference, &oid) ? 1 : 0;
 	if (!s.is_initial)
 		hashcpy(s.sha1_commit, oid.hash);
 
@@ -1657,7 +1657,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 	status_format = STATUS_FORMAT_NONE; /* Ignore status.short */
 	s.colopts = 0;
 
-	if (get_sha1("HEAD", oid.hash))
+	if (get_oid("HEAD", &oid))
 		current_head = NULL;
 	else {
 		current_head = lookup_commit_or_die(&oid, "HEAD");
@@ -1739,17 +1739,17 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 	if (verbose || /* Truncate the message just before the diff, if any. */
 	    cleanup_mode == CLEANUP_SCISSORS)
 		strbuf_setlen(&sb, wt_status_locate_end(sb.buf, sb.len));
-
 	if (cleanup_mode != CLEANUP_NONE)
 		strbuf_stripspace(&sb, cleanup_mode == CLEANUP_ALL);
-	if (template_untouched(&sb) && !allow_empty_message) {
+
+	if (message_is_empty(&sb) && !allow_empty_message) {
 		rollback_index_files();
-		fprintf(stderr, _("Aborting commit; you did not edit the message.\n"));
+		fprintf(stderr, _("Aborting commit due to empty commit message.\n"));
 		exit(1);
 	}
-	if (message_is_empty(&sb) && !allow_empty_message) {
+	if (template_untouched(&sb) && !allow_empty_message) {
 		rollback_index_files();
-		fprintf(stderr, _("Aborting commit due to empty commit message.\n"));
+		fprintf(stderr, _("Aborting commit; you did not edit the message.\n"));
 		exit(1);
 	}
 
diff --git a/builtin/describe.c b/builtin/describe.c
index 89ea1cdd60..9c13c6817b 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -55,10 +55,13 @@ static const char *prio_names[] = {
 };
 
 static int commit_name_cmp(const void *unused_cmp_data,
-			   const struct commit_name *cn1,
-			   const struct commit_name *cn2,
+			   const void *entry,
+			   const void *entry_or_key,
 			   const void *peeled)
 {
+	const struct commit_name *cn1 = entry;
+	const struct commit_name *cn2 = entry_or_key;
+
 	return oidcmp(&cn1->peeled, peeled ? peeled : &cn2->peeled);
 }
 
@@ -503,7 +506,7 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
 		return cmd_name_rev(args.argc, args.argv, prefix);
 	}
 
-	hashmap_init(&names, (hashmap_cmp_fn) commit_name_cmp, NULL, 0);
+	hashmap_init(&names, commit_name_cmp, NULL, 0);
 	for_each_rawref(get_name, NULL);
 	if (!names.size && !always)
 		die(_("No names found, cannot describe anything."));
diff --git a/builtin/difftool.c b/builtin/difftool.c
index a1a26ba891..8864d846f8 100644
--- a/builtin/difftool.c
+++ b/builtin/difftool.c
@@ -131,10 +131,12 @@ struct working_tree_entry {
 };
 
 static int working_tree_entry_cmp(const void *unused_cmp_data,
-				  struct working_tree_entry *a,
-				  struct working_tree_entry *b,
-				  void *unused_keydata)
+				  const void *entry,
+				  const void *entry_or_key,
+				  const void *unused_keydata)
 {
+	const struct working_tree_entry *a = entry;
+	const struct working_tree_entry *b = entry_or_key;
 	return strcmp(a->path, b->path);
 }
 
@@ -149,9 +151,13 @@ struct pair_entry {
 };
 
 static int pair_cmp(const void *unused_cmp_data,
-		    struct pair_entry *a, struct pair_entry *b,
-		    void *unused_keydata)
+		    const void *entry,
+		    const void *entry_or_key,
+		    const void *unused_keydata)
 {
+	const struct pair_entry *a = entry;
+	const struct pair_entry *b = entry_or_key;
+
 	return strcmp(a->path, b->path);
 }
 
@@ -179,9 +185,13 @@ struct path_entry {
 };
 
 static int path_entry_cmp(const void *unused_cmp_data,
-			  struct path_entry *a, struct path_entry *b,
-			  void *key)
+			  const void *entry,
+			  const void *entry_or_key,
+			  const void *key)
 {
+	const struct path_entry *a = entry;
+	const struct path_entry *b = entry_or_key;
+
 	return strcmp(a->path, key ? key : b->path);
 }
 
@@ -372,10 +382,9 @@ static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 	rdir_len = rdir.len;
 	wtdir_len = wtdir.len;
 
-	hashmap_init(&working_tree_dups,
-		     (hashmap_cmp_fn)working_tree_entry_cmp, NULL, 0);
-	hashmap_init(&submodules, (hashmap_cmp_fn)pair_cmp, NULL, 0);
-	hashmap_init(&symlinks2, (hashmap_cmp_fn)pair_cmp, NULL, 0);
+	hashmap_init(&working_tree_dups, working_tree_entry_cmp, NULL, 0);
+	hashmap_init(&submodules, pair_cmp, NULL, 0);
+	hashmap_init(&symlinks2, pair_cmp, NULL, 0);
 
 	child.no_stdin = 1;
 	child.git_cmd = 1;
@@ -585,10 +594,8 @@ static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
 	 * in the common case of --symlinks and the difftool updating
 	 * files through the symlink.
 	 */
-	hashmap_init(&wt_modified, (hashmap_cmp_fn)path_entry_cmp,
-		     NULL, wtindex.cache_nr);
-	hashmap_init(&tmp_modified, (hashmap_cmp_fn)path_entry_cmp,
-		     NULL, wtindex.cache_nr);
+	hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
+	hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
 
 	for (i = 0; i < wtindex.cache_nr; i++) {
 		struct hashmap_entry dummy;
diff --git a/builtin/fmt-merge-msg.c b/builtin/fmt-merge-msg.c
index 10cbb43416..e99b5ddbf9 100644
--- a/builtin/fmt-merge-msg.c
+++ b/builtin/fmt-merge-msg.c
@@ -408,7 +408,8 @@ static void shortlog(const char *name,
 }
 
 static void fmt_merge_msg_title(struct strbuf *out,
-	const char *current_branch) {
+				const char *current_branch)
+{
 	int i = 0;
 	char *sep = "";
 
diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 52be99cbac..5d7c921a77 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -17,25 +17,25 @@ static char const * const for_each_ref_usage[] = {
 int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 {
 	int i;
-	const char *format = "%(objectname) %(objecttype)\t%(refname)";
 	struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
-	int maxcount = 0, quote_style = 0, icase = 0;
+	int maxcount = 0, icase = 0;
 	struct ref_array array;
 	struct ref_filter filter;
+	struct ref_format format = REF_FORMAT_INIT;
 
 	struct option opts[] = {
-		OPT_BIT('s', "shell", &quote_style,
+		OPT_BIT('s', "shell", &format.quote_style,
 			N_("quote placeholders suitably for shells"), QUOTE_SHELL),
-		OPT_BIT('p', "perl",  &quote_style,
+		OPT_BIT('p', "perl",  &format.quote_style,
 			N_("quote placeholders suitably for perl"), QUOTE_PERL),
-		OPT_BIT(0 , "python", &quote_style,
+		OPT_BIT(0 , "python", &format.quote_style,
 			N_("quote placeholders suitably for python"), QUOTE_PYTHON),
-		OPT_BIT(0 , "tcl",  &quote_style,
+		OPT_BIT(0 , "tcl",  &format.quote_style,
 			N_("quote placeholders suitably for Tcl"), QUOTE_TCL),
 
 		OPT_GROUP(""),
 		OPT_INTEGER( 0 , "count", &maxcount, N_("show only <n> matched refs")),
-		OPT_STRING(  0 , "format", &format, N_("format"), N_("format to use for the output")),
+		OPT_STRING(  0 , "format", &format.format, N_("format"), N_("format to use for the output")),
 		OPT_CALLBACK(0 , "sort", sorting_tail, N_("key"),
 			    N_("field name to sort on"), &parse_opt_ref_sorting),
 		OPT_CALLBACK(0, "points-at", &filter.points_at,
@@ -52,16 +52,20 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 	memset(&array, 0, sizeof(array));
 	memset(&filter, 0, sizeof(filter));
 
+	format.format = "%(objectname) %(objecttype)\t%(refname)";
+
+	git_config(git_default_config, NULL);
+
 	parse_options(argc, argv, prefix, opts, for_each_ref_usage, 0);
 	if (maxcount < 0) {
 		error("invalid --count argument: `%d'", maxcount);
 		usage_with_options(for_each_ref_usage, opts);
 	}
-	if (HAS_MULTI_BITS(quote_style)) {
+	if (HAS_MULTI_BITS(format.quote_style)) {
 		error("more than one quoting style?");
 		usage_with_options(for_each_ref_usage, opts);
 	}
-	if (verify_ref_format(format))
+	if (verify_ref_format(&format))
 		usage_with_options(for_each_ref_usage, opts);
 
 	if (!sorting)
@@ -69,9 +73,6 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 	sorting->ignore_case = icase;
 	filter.ignore_case = icase;
 
-	/* for warn_ambiguous_refs */
-	git_config(git_default_config, NULL);
-
 	filter.name_patterns = argv;
 	filter.match_as_path = 1;
 	filter_refs(&array, &filter, FILTER_REFS_ALL | FILTER_REFS_INCLUDE_BROKEN);
@@ -80,7 +81,7 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 	if (!maxcount || array.nr < maxcount)
 		maxcount = array.nr;
 	for (i = 0; i < maxcount; i++)
-		show_ref_array_item(array.items[i], format, quote_style);
+		show_ref_array_item(array.items[i], &format);
 	ref_array_clear(&array);
 	return 0;
 }
diff --git a/builtin/fsck.c b/builtin/fsck.c
index 99dea7adf6..a92f448186 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -19,6 +19,8 @@
 #define REACHABLE 0x0001
 #define SEEN      0x0002
 #define HAS_OBJ   0x0004
+/* This flag is set if something points to this object. */
+#define USED      0x0008
 
 static int show_root;
 static int show_tags;
@@ -168,18 +170,7 @@ static void mark_object_reachable(struct object *obj)
 
 static int traverse_one_object(struct object *obj)
 {
-	int result;
-	struct tree *tree = NULL;
-
-	if (obj->type == OBJ_TREE) {
-		tree = (struct tree *)obj;
-		if (parse_tree(tree) < 0)
-			return 1; /* error already displayed */
-	}
-	result = fsck_walk(obj, obj, &fsck_walk_options);
-	if (tree)
-		free_tree_buffer(tree);
-	return result;
+	return fsck_walk(obj, obj, &fsck_walk_options);
 }
 
 static int traverse_reachable(void)
@@ -206,7 +197,7 @@ static int mark_used(struct object *obj, int type, void *data, struct fsck_optio
 {
 	if (!obj)
 		return 1;
-	obj->used = 1;
+	obj->flags |= USED;
 	return 0;
 }
 
@@ -255,7 +246,7 @@ static void check_unreachable_object(struct object *obj)
 	}
 
 	/*
-	 * "!used" means that nothing at all points to it, including
+	 * "!USED" means that nothing at all points to it, including
 	 * other unreachable objects. In other words, it's the "tip"
 	 * of some set of unreachable objects, usually a commit that
 	 * got dropped.
@@ -266,7 +257,7 @@ static void check_unreachable_object(struct object *obj)
 	 * deleted a branch by mistake, this is a prime candidate to
 	 * start looking at, for example.
 	 */
-	if (!obj->used) {
+	if (!(obj->flags & USED)) {
 		if (show_dangling)
 			printf("dangling %s %s\n", printable_type(obj),
 			       describe_object(obj));
@@ -390,7 +381,8 @@ static int fsck_obj_buffer(const struct object_id *oid, enum object_type type,
 		errors_found |= ERROR_OBJECT;
 		return error("%s: object corrupt or missing", oid_to_hex(oid));
 	}
-	obj->flags = HAS_OBJ;
+	obj->flags &= ~(REACHABLE | SEEN);
+	obj->flags |= HAS_OBJ;
 	return fsck_obj(obj);
 }
 
@@ -408,7 +400,7 @@ static void fsck_handle_reflog_oid(const char *refname, struct object_id *oid,
 				add_decoration(fsck_walk_options.object_names,
 					obj,
 					xstrfmt("%s@{%"PRItime"}", refname, timestamp));
-			obj->used = 1;
+			obj->flags |= USED;
 			mark_object_reachable(obj);
 		} else {
 			error("%s: invalid reflog entry %s", refname, oid_to_hex(oid));
@@ -456,7 +448,7 @@ static int fsck_handle_ref(const char *refname, const struct object_id *oid,
 		errors_found |= ERROR_REFS;
 	}
 	default_refs++;
-	obj->used = 1;
+	obj->flags |= USED;
 	if (name_objects)
 		add_decoration(fsck_walk_options.object_names,
 			obj, xstrdup(refname));
@@ -524,7 +516,8 @@ static int fsck_loose(const struct object_id *oid, const char *path, void *data)
 		return 0; /* keep checking other objects */
 	}
 
-	obj->flags = HAS_OBJ;
+	obj->flags &= ~(REACHABLE | SEEN);
+	obj->flags |= HAS_OBJ;
 	if (fsck_obj(obj))
 		errors_found |= ERROR_OBJECT;
 	return 0;
@@ -606,7 +599,7 @@ static int fsck_cache_tree(struct cache_tree *it)
 			errors_found |= ERROR_REFS;
 			return 1;
 		}
-		obj->used = 1;
+		obj->flags |= USED;
 		if (name_objects)
 			add_decoration(fsck_walk_options.object_names,
 				obj, xstrdup(":"));
@@ -667,7 +660,7 @@ static struct option fsck_opts[] = {
 
 int cmd_fsck(int argc, const char **argv, const char *prefix)
 {
-	int i, heads;
+	int i;
 	struct alternate_object_database *alt;
 
 	errors_found = 0;
@@ -735,25 +728,23 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 		}
 	}
 
-	heads = 0;
 	for (i = 0; i < argc; i++) {
 		const char *arg = argv[i];
-		unsigned char sha1[20];
-		if (!get_sha1(arg, sha1)) {
-			struct object *obj = lookup_object(sha1);
+		struct object_id oid;
+		if (!get_oid(arg, &oid)) {
+			struct object *obj = lookup_object(oid.hash);
 
 			if (!obj || !(obj->flags & HAS_OBJ)) {
-				error("%s: object missing", sha1_to_hex(sha1));
+				error("%s: object missing", oid_to_hex(&oid));
 				errors_found |= ERROR_OBJECT;
 				continue;
 			}
 
-			obj->used = 1;
+			obj->flags |= USED;
 			if (name_objects)
 				add_decoration(fsck_walk_options.object_names,
 					obj, xstrdup(arg));
 			mark_object_reachable(obj);
-			heads++;
 			continue;
 		}
 		error("invalid parameter: expected sha1, got '%s'", arg);
@@ -785,7 +776,7 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 			if (!blob)
 				continue;
 			obj = &blob->object;
-			obj->used = 1;
+			obj->flags |= USED;
 			if (name_objects)
 				add_decoration(fsck_walk_options.object_names,
 					obj,
diff --git a/builtin/gc.c b/builtin/gc.c
index 2ba50a2873..e6b84475ae 100644
--- a/builtin/gc.c
+++ b/builtin/gc.c
@@ -414,8 +414,12 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 			if (report_last_gc_error())
 				return -1;
 
+			if (lock_repo_for_gc(force, &pid))
+				return 0;
 			if (gc_before_repack())
 				return -1;
+			delete_tempfile(&pidfile);
+
 			/*
 			 * failure to daemonize is ok, we'll continue
 			 * in foreground
diff --git a/builtin/grep.c b/builtin/grep.c
index cd0e51f3c0..a70d8e2fba 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -275,7 +275,7 @@ static int wait_all(void)
 static int grep_cmd_config(const char *var, const char *value, void *cb)
 {
 	int st = grep_config(var, value, cb);
-	if (git_color_default_config(var, value, cb) < 0)
+	if (git_default_config(var, value, cb) < 0)
 		st = -1;
 
 	if (!strcmp(var, "grep.threads")) {
@@ -643,7 +643,7 @@ static int grep_objects(struct grep_opt *opt, const struct pathspec *pathspec,
 		/* load the gitmodules file for this rev */
 		if (recurse_submodules) {
 			submodule_free();
-			gitmodules_config_sha1(real_obj->oid.hash);
+			gitmodules_config_oid(&real_obj->oid);
 		}
 		if (grep_object(opt, pathspec, real_obj, list->objects[i].name, list->objects[i].path,
 				repo)) {
@@ -983,8 +983,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			break;
 		}
 
-		if (get_sha1_with_context(arg, GET_SHA1_RECORD_PATH,
-					  oid.hash, &oc)) {
+		if (get_oid_with_context(arg, GET_OID_RECORD_PATH,
+					 &oid, &oc)) {
 			if (seen_dashdash)
 				die(_("unable to resolve revision: %s"), arg);
 			break;
diff --git a/builtin/log.c b/builtin/log.c
index c6362cf92e..725c7b8a1a 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -372,11 +372,14 @@ static int cmd_log_walk(struct rev_info *rev)
 			 */
 			rev->max_count++;
 		if (!rev->reflog_info) {
-			/* we allow cycles in reflog ancestry */
+			/*
+			 * We may show a given commit multiple times when
+			 * walking the reflogs.
+			 */
 			free_commit_buffer(commit);
+			free_commit_list(commit->parents);
+			commit->parents = NULL;
 		}
-		free_commit_list(commit->parents);
-		commit->parents = NULL;
 		if (saved_nrl < rev->diffopt.needed_rename_limit)
 			saved_nrl = rev->diffopt.needed_rename_limit;
 		if (rev->diffopt.degraded_cc_to_c)
@@ -484,8 +487,8 @@ static int show_blob_object(const struct object_id *oid, struct rev_info *rev, c
 	    !DIFF_OPT_TST(&rev->diffopt, ALLOW_TEXTCONV))
 		return stream_blob_to_fd(1, oid, NULL, 0);
 
-	if (get_sha1_with_context(obj_name, GET_SHA1_RECORD_PATH,
-				  oidc.hash, &obj_context))
+	if (get_oid_with_context(obj_name, GET_OID_RECORD_PATH,
+				 &oidc, &obj_context))
 		die(_("Not a valid object name %s"), obj_name);
 	if (!obj_context.path ||
 	    !textconv_object(obj_context.path, obj_context.mode, &oidc, 1, &buf, &size)) {
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index b8514a0029..c6126eae55 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -362,7 +362,7 @@ static void prune_index(struct index_state *istate,
 	int pos;
 	unsigned int first, last;
 
-	if (!prefix)
+	if (!prefix || !istate->cache_nr)
 		return;
 	pos = index_name_pos(istate, prefix, prefixlen);
 	if (pos < 0)
@@ -378,8 +378,7 @@ static void prune_index(struct index_state *istate,
 		}
 		last = next;
 	}
-	memmove(istate->cache, istate->cache + pos,
-		(last - pos) * sizeof(struct cache_entry *));
+	MOVE_ARRAY(istate->cache, istate->cache + pos, last - pos);
 	istate->cache_nr = last - pos;
 }
 
diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index bad6735c76..f12da292cf 100644
--- a/builtin/merge-tree.c
+++ b/builtin/merge-tree.c
@@ -347,12 +347,12 @@ static void merge_trees(struct tree_desc t[3], const char *base)
 
 static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
 {
-	unsigned char sha1[20];
+	struct object_id oid;
 	void *buf;
 
-	if (get_sha1(rev, sha1))
+	if (get_oid(rev, &oid))
 		die("unknown rev %s", rev);
-	buf = fill_tree_descriptor(desc, sha1);
+	buf = fill_tree_descriptor(desc, oid.hash);
 	if (!buf)
 		die("%s is not a tree", rev);
 	return buf;
diff --git a/builtin/merge.c b/builtin/merge.c
index 900bafdb45..d5797b8fe7 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -537,7 +537,7 @@ static void parse_branch_merge_options(char *bmo)
 		die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 		    split_cmdline_strerror(argc));
 	REALLOC_ARRAY(argv, argc + 2);
-	memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
+	MOVE_ARRAY(argv + 1, argv, argc + 1);
 	argc++;
 	argv[0] = "branch.*.mergeoptions";
 	parse_options(argc, argv, NULL, builtin_merge_options,
diff --git a/builtin/notes.c b/builtin/notes.c
index 77573cf1ea..4303848e04 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -456,7 +456,7 @@ static int add(int argc, const char **argv, const char *prefix)
 			oid_to_hex(&object));
 	}
 
-	prepare_note_data(&object, &d, note->hash);
+	prepare_note_data(&object, &d, note ? note->hash : NULL);
 	if (d.buf.len || allow_empty) {
 		write_note_data(&d, new_note.hash);
 		if (add_note(t, &object, &new_note, combine_notes_overwrite))
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index f4a8441fe9..c753e9237a 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -1289,7 +1289,7 @@ static int done_pbase_path_pos(unsigned hash)
 
 static int check_pbase_path(unsigned hash)
 {
-	int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
+	int pos = done_pbase_path_pos(hash);
 	if (0 <= pos)
 		return 1;
 	pos = -pos - 1;
@@ -1298,9 +1298,8 @@ static int check_pbase_path(unsigned hash)
 		   done_pbase_paths_alloc);
 	done_pbase_paths_num++;
 	if (pos < done_pbase_paths_num)
-		memmove(done_pbase_paths + pos + 1,
-			done_pbase_paths + pos,
-			(done_pbase_paths_num - pos - 1) * sizeof(unsigned));
+		MOVE_ARRAY(done_pbase_paths + pos + 1, done_pbase_paths + pos,
+			   done_pbase_paths_num - pos - 1);
 	done_pbase_paths[pos] = hash;
 	return 0;
 }
diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index cabdc55e09..14b6e09b42 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -919,9 +919,9 @@ static int update_shallow_ref(struct command *cmd, struct shallow_info *si)
  */
 static int head_has_history(void)
 {
-	unsigned char sha1[20];
+	struct object_id oid;
 
-	return !get_sha1("HEAD", sha1);
+	return !get_oid("HEAD", &oid);
 }
 
 static const char *push_to_deploy(unsigned char *sha1,
@@ -1138,7 +1138,7 @@ static const char *update(struct command *cmd, struct shallow_info *si)
 		}
 		if (ref_transaction_delete(transaction,
 					   namespaced_name,
-					   old_oid->hash,
+					   old_oid ? old_oid->hash : NULL,
 					   0, "push", &err)) {
 			rp_error("%s", err.buf);
 			strbuf_release(&err);
diff --git a/builtin/replace.c b/builtin/replace.c
index fba336a68a..f4a85a165b 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -50,7 +50,7 @@ static int show_reference(const char *refname, const struct object_id *oid,
 			struct object_id object;
 			enum object_type obj_type, repl_type;
 
-			if (get_sha1(refname, object.hash))
+			if (get_oid(refname, &object))
 				return error("Failed to resolve '%s' as a valid ref.", refname);
 
 			obj_type = sha1_object_info(object.hash, NULL);
@@ -365,7 +365,7 @@ static void check_one_mergetag(struct commit *commit,
 	/* iterate over new parents */
 	for (i = 1; i < mergetag_data->argc; i++) {
 		struct object_id oid;
-		if (get_sha1(mergetag_data->argv[i], oid.hash) < 0)
+		if (get_oid(mergetag_data->argv[i], &oid) < 0)
 			die(_("Not a valid object name: '%s'"), mergetag_data->argv[i]);
 		if (!oidcmp(&tag->tagged->oid, &oid))
 			return; /* found */
diff --git a/builtin/reset.c b/builtin/reset.c
index 7aeaea2737..046403ed68 100644
--- a/builtin/reset.c
+++ b/builtin/reset.c
@@ -219,8 +219,8 @@ static void parse_args(struct pathspec *pathspec,
 		 * has to be unambiguous. If there is a single argument, it
 		 * can not be a tree
 		 */
-		else if ((!argv[1] && !get_sha1_committish(argv[0], unused.hash)) ||
-			 (argv[1] && !get_sha1_treeish(argv[0], unused.hash))) {
+		else if ((!argv[1] && !get_oid_committish(argv[0], &unused)) ||
+			 (argv[1] && !get_oid_treeish(argv[0], &unused))) {
 			/*
 			 * Ok, argv[0] looks like a commit/tree; it should not
 			 * be a filename.
@@ -310,13 +310,13 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 
 	load_submodule_cache();
 
-	unborn = !strcmp(rev, "HEAD") && get_sha1("HEAD", oid.hash);
+	unborn = !strcmp(rev, "HEAD") && get_oid("HEAD", &oid);
 	if (unborn) {
 		/* reset on unborn branch: treat as reset to empty tree */
 		hashcpy(oid.hash, EMPTY_TREE_SHA1_BIN);
 	} else if (!pathspec.nr) {
 		struct commit *commit;
-		if (get_sha1_committish(rev, oid.hash))
+		if (get_oid_committish(rev, &oid))
 			die(_("Failed to resolve '%s' as a valid revision."), rev);
 		commit = lookup_commit_reference(&oid);
 		if (!commit)
@@ -324,7 +324,7 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 		oidcpy(&oid, &commit->object.oid);
 	} else {
 		struct tree *tree;
-		if (get_sha1_treeish(rev, oid.hash))
+		if (get_oid_treeish(rev, &oid))
 			die(_("Failed to resolve '%s' as a valid tree."), rev);
 		tree = parse_tree_indirect(&oid);
 		if (!tree)
diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index 95d84d5cda..95b4128250 100644
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -11,6 +11,7 @@
 #include "graph.h"
 #include "bisect.h"
 #include "progress.h"
+#include "reflog-walk.h"
 
 static const char rev_list_usage[] =
 "git rev-list [OPTION] <commit-id>... [ -- paths... ]\n"
@@ -122,6 +123,7 @@ static void show_commit(struct commit *commit, void *data)
 		ctx.date_mode_explicit = revs->date_mode_explicit;
 		ctx.fmt = revs->commit_format;
 		ctx.output_encoding = get_log_output_encoding();
+		ctx.color = revs->diffopt.use_color;
 		pretty_print_commit(&ctx, commit, &buf);
 		if (buf.len) {
 			if (revs->commit_format != CMIT_FMT_ONELINE)
@@ -348,9 +350,10 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
 		/* Only --header was specified */
 		revs.commit_format = CMIT_FMT_RAW;
 
-	if ((!revs.commits &&
+	if ((!revs.commits && reflog_walk_empty(revs.reflog_info) &&
 	     (!(revs.tag_objects || revs.tree_objects || revs.blob_objects) &&
-	      !revs.pending.nr)) ||
+	      !revs.pending.nr) &&
+	     !revs.rev_input_given) ||
 	    revs.diff)
 		usage(rev_list_usage);
 
diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index c78b7b33d6..2bd28d3c08 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -274,7 +274,7 @@ static int try_difference(const char *arg)
 		return 0;
 	}
 
-	if (!get_sha1_committish(this, oid.hash) && !get_sha1_committish(next, end.hash)) {
+	if (!get_oid_committish(this, &oid) && !get_oid_committish(next, &end)) {
 		show_rev(NORMAL, &end, next);
 		show_rev(symmetric ? NORMAL : REVERSED, &oid, this);
 		if (symmetric) {
@@ -328,7 +328,7 @@ static int try_parent_shorthands(const char *arg)
 		return 0;
 
 	*dotdot = 0;
-	if (get_sha1_committish(arg, oid.hash)) {
+	if (get_oid_committish(arg, &oid)) {
 		*dotdot = '^';
 		return 0;
 	}
@@ -702,7 +702,7 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 			}
 			if (!strcmp(arg, "--quiet") || !strcmp(arg, "-q")) {
 				quiet = 1;
-				flags |= GET_SHA1_QUIETLY;
+				flags |= GET_OID_QUIETLY;
 				continue;
 			}
 			if (opt_with_value(arg, "--short", &arg)) {
@@ -911,7 +911,7 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 			name++;
 			type = REVERSED;
 		}
-		if (!get_sha1_with_context(name, flags, oid.hash, &unused)) {
+		if (!get_oid_with_context(name, flags, &oid, &unused)) {
 			if (verify)
 				revs_count++;
 			else
diff --git a/builtin/revert.c b/builtin/revert.c
index 16028b9ea8..b9d927eb09 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -155,6 +155,8 @@ static int run_sequencer(int argc, const char **argv, struct replay_opts *opts)
 				"--strategy-option", opts->xopts ? 1 : 0,
 				"-x", opts->record_origin,
 				"--ff", opts->allow_ff,
+				"--rerere-autoupdate", opts->allow_rerere_auto == RERERE_AUTOUPDATE,
+				"--no-rerere-autoupdate", opts->allow_rerere_auto == RERERE_NOAUTOUPDATE,
 				NULL);
 	}
 
diff --git a/builtin/show-branch.c b/builtin/show-branch.c
index 7073a3eb97..84547d6fba 100644
--- a/builtin/show-branch.c
+++ b/builtin/show-branch.c
@@ -393,7 +393,7 @@ static int append_head_ref(const char *refname, const struct object_id *oid,
 	/* If both heads/foo and tags/foo exists, get_sha1 would
 	 * get confused.
 	 */
-	if (get_sha1(refname + ofs, tmp.hash) || oidcmp(&tmp, oid))
+	if (get_oid(refname + ofs, &tmp) || oidcmp(&tmp, oid))
 		ofs = 5;
 	return append_ref(refname + ofs, oid, 0);
 }
@@ -408,7 +408,7 @@ static int append_remote_ref(const char *refname, const struct object_id *oid,
 	/* If both heads/foo and tags/foo exists, get_sha1 would
 	 * get confused.
 	 */
-	if (get_sha1(refname + ofs, tmp.hash) || oidcmp(&tmp, oid))
+	if (get_oid(refname + ofs, &tmp) || oidcmp(&tmp, oid))
 		ofs = 5;
 	return append_ref(refname + ofs, oid, 0);
 }
@@ -514,7 +514,7 @@ static int show_independent(struct commit **rev,
 static void append_one_rev(const char *av)
 {
 	struct object_id revkey;
-	if (!get_sha1(av, revkey.hash)) {
+	if (!get_oid(av, &revkey)) {
 		append_ref(av, &revkey, 0);
 		return;
 	}
@@ -554,7 +554,7 @@ static int git_show_branch_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
-	return git_color_default_config(var, value, cb);
+	return git_default_config(var, value, cb);
 }
 
 static int omit_in_dense(struct commit *commit, struct commit **rev, int n)
@@ -808,7 +808,7 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 			die(Q_("cannot handle more than %d rev.",
 			       "cannot handle more than %d revs.",
 			       MAX_REVS), MAX_REVS);
-		if (get_sha1(ref_name[num_rev], revkey.hash))
+		if (get_oid(ref_name[num_rev], &revkey))
 			die(_("'%s' is not a valid ref."), ref_name[num_rev]);
 		commit = lookup_commit_reference(&revkey);
 		if (!commit)
diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
index 6d9600d4fb..0ff9dd0b85 100644
--- a/builtin/submodule--helper.c
+++ b/builtin/submodule--helper.c
@@ -350,7 +350,7 @@ static void init_submodule(const char *path, const char *prefix, int quiet)
 	} else
 		displaypath = xstrdup(path);
 
-	sub = submodule_from_path(null_sha1, path);
+	sub = submodule_from_path(&null_oid, path);
 
 	if (!sub)
 		die(_("No url found for submodule path '%s' in .gitmodules"),
@@ -476,7 +476,7 @@ static int module_name(int argc, const char **argv, const char *prefix)
 		usage(_("git submodule--helper name <path>"));
 
 	gitmodules_config();
-	sub = submodule_from_path(null_sha1, argv[1]);
+	sub = submodule_from_path(&null_oid, argv[1]);
 
 	if (!sub)
 		die(_("no submodule mapping found in .gitmodules for path '%s'"),
@@ -795,7 +795,7 @@ static int prepare_to_clone_next_submodule(const struct cache_entry *ce,
 		goto cleanup;
 	}
 
-	sub = submodule_from_path(null_sha1, ce->name);
+	sub = submodule_from_path(&null_oid, ce->name);
 
 	if (suc->recursive_prefix)
 		displaypath = relative_path(suc->recursive_prefix,
@@ -930,7 +930,7 @@ static int update_clone_task_finished(int result,
 	const struct cache_entry *ce;
 	struct submodule_update_clone *suc = suc_cb;
 
-	int *idxP = *(int**)idx_task_cb;
+	int *idxP = idx_task_cb;
 	int idx = *idxP;
 	free(idxP);
 
@@ -1069,7 +1069,7 @@ static const char *remote_submodule_branch(const char *path)
 	gitmodules_config();
 	git_config(submodule_config, NULL);
 
-	sub = submodule_from_path(null_sha1, path);
+	sub = submodule_from_path(&null_oid, path);
 	if (!sub)
 		return NULL;
 
@@ -1117,9 +1117,28 @@ static int resolve_remote_submodule_branch(int argc, const char **argv,
 static int push_check(int argc, const char **argv, const char *prefix)
 {
 	struct remote *remote;
+	const char *superproject_head;
+	char *head;
+	int detached_head = 0;
+	struct object_id head_oid;
 
-	if (argc < 2)
-		die("submodule--helper push-check requires at least 1 argument");
+	if (argc < 3)
+		die("submodule--helper push-check requires at least 2 arguments");
+
+	/*
+	 * superproject's resolved head ref.
+	 * if HEAD then the superproject is in a detached head state, otherwise
+	 * it will be the resolved head ref.
+	 */
+	superproject_head = argv[1];
+	argv++;
+	argc--;
+	/* Get the submodule's head ref and determine if it is detached */
+	head = resolve_refdup("HEAD", 0, head_oid.hash, NULL);
+	if (!head)
+		die(_("Failed to resolve HEAD as a valid ref."));
+	if (!strcmp(head, "HEAD"))
+		detached_head = 1;
 
 	/*
 	 * The remote must be configured.
@@ -1142,18 +1161,30 @@ static int push_check(int argc, const char **argv, const char *prefix)
 			if (rs->pattern || rs->matching)
 				continue;
 
-			/*
-			 * LHS must match a single ref
-			 * NEEDSWORK: add logic to special case 'HEAD' once
-			 * working with submodules in a detached head state
-			 * ceases to be the norm.
-			 */
-			if (count_refspec_match(rs->src, local_refs, NULL) != 1)
+			/* LHS must match a single ref */
+			switch (count_refspec_match(rs->src, local_refs, NULL)) {
+			case 1:
+				break;
+			case 0:
+				/*
+				 * If LHS matches 'HEAD' then we need to ensure
+				 * that it matches the same named branch
+				 * checked out in the superproject.
+				 */
+				if (!strcmp(rs->src, "HEAD")) {
+					if (!detached_head &&
+					    !strcmp(head, superproject_head))
+						break;
+					die("HEAD does not match the named branch in the superproject");
+				}
+			default:
 				die("src refspec '%s' must name a ref",
 				    rs->src);
+			}
 		}
 		free_refspec(refspec_nr, refspec);
 	}
+	free(head);
 
 	return 0;
 }
diff --git a/builtin/tag.c b/builtin/tag.c
index 01154ea8dc..c627794181 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -32,7 +32,8 @@ static const char * const git_tag_usage[] = {
 static unsigned int colopts;
 static int force_sign_annotate;
 
-static int list_tags(struct ref_filter *filter, struct ref_sorting *sorting, const char *format)
+static int list_tags(struct ref_filter *filter, struct ref_sorting *sorting,
+		     struct ref_format *format)
 {
 	struct ref_array array;
 	char *to_free = NULL;
@@ -43,23 +44,24 @@ static int list_tags(struct ref_filter *filter, struct ref_sorting *sorting, con
 	if (filter->lines == -1)
 		filter->lines = 0;
 
-	if (!format) {
+	if (!format->format) {
 		if (filter->lines) {
 			to_free = xstrfmt("%s %%(contents:lines=%d)",
 					  "%(align:15)%(refname:lstrip=2)%(end)",
 					  filter->lines);
-			format = to_free;
+			format->format = to_free;
 		} else
-			format = "%(refname:lstrip=2)";
+			format->format = "%(refname:lstrip=2)";
 	}
 
-	verify_ref_format(format);
+	if (verify_ref_format(format))
+		die(_("unable to parse format string"));
 	filter->with_commit_tag_algo = 1;
 	filter_refs(&array, filter, FILTER_REFS_TAGS);
 	ref_array_sort(sorting, &array);
 
 	for (i = 0; i < array.nr; i++)
-		show_ref_array_item(array.items[i], format, 0);
+		show_ref_array_item(array.items[i], format);
 	ref_array_clear(&array);
 	free(to_free);
 
@@ -105,17 +107,17 @@ static int verify_tag(const char *name, const char *ref,
 		      const struct object_id *oid, const void *cb_data)
 {
 	int flags;
-	const char *fmt_pretty = cb_data;
+	const struct ref_format *format = cb_data;
 	flags = GPG_VERIFY_VERBOSE;
 
-	if (fmt_pretty)
+	if (format->format)
 		flags = GPG_VERIFY_OMIT_STATUS;
 
-	if (gpg_verify_tag(oid->hash, name, flags))
+	if (gpg_verify_tag(oid, name, flags))
 		return -1;
 
-	if (fmt_pretty)
-		pretty_print_ref(name, oid->hash, fmt_pretty);
+	if (format->format)
+		pretty_print_ref(name, oid->hash, format);
 
 	return 0;
 }
@@ -134,30 +136,6 @@ static const char tag_template_nocleanup[] =
 	"Lines starting with '%c' will be kept; you may remove them"
 	" yourself if you want to.\n");
 
-/* Parse arg given and add it the ref_sorting array */
-static int parse_sorting_string(const char *arg, struct ref_sorting **sorting_tail)
-{
-	struct ref_sorting *s;
-	int len;
-
-	s = xcalloc(1, sizeof(*s));
-	s->next = *sorting_tail;
-	*sorting_tail = s;
-
-	if (*arg == '-') {
-		s->reverse = 1;
-		arg++;
-	}
-	if (skip_prefix(arg, "version:", &arg) ||
-	    skip_prefix(arg, "v:", &arg))
-		s->version = 1;
-
-	len = strlen(arg);
-	s->atom = parse_ref_filter_atom(arg, arg+len);
-
-	return 0;
-}
-
 static int git_tag_config(const char *var, const char *value, void *cb)
 {
 	int status;
@@ -166,7 +144,7 @@ static int git_tag_config(const char *var, const char *value, void *cb)
 	if (!strcmp(var, "tag.sort")) {
 		if (!value)
 			return config_error_nonbool(var);
-		parse_sorting_string(value, sorting_tail);
+		parse_ref_sorting(sorting_tail, value);
 		return 0;
 	}
 
@@ -392,7 +370,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 	struct strbuf err = STRBUF_INIT;
 	struct ref_filter filter;
 	static struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
-	const char *format = NULL;
+	struct ref_format format = REF_FORMAT_INIT;
 	int icase = 0;
 	struct option options[] = {
 		OPT_CMDMODE('l', "list", &cmdmode, N_("list tag names"), 'l'),
@@ -431,7 +409,8 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 			N_("print only tags of the object"), PARSE_OPT_LASTARG_DEFAULT,
 			parse_opt_object_name, (intptr_t) "HEAD"
 		},
-		OPT_STRING(  0 , "format", &format, N_("format"), N_("format to use for the output")),
+		OPT_STRING(  0 , "format", &format.format, N_("format"),
+			   N_("format to use for the output")),
 		OPT_BOOL('i', "ignore-case", &icase, N_("sorting and filtering are case insensitive")),
 		OPT_END()
 	};
@@ -461,6 +440,9 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 			cmdmode = 'l';
 	}
 
+	if (cmdmode == 'l')
+		setup_auto_pager("tag", 1);
+
 	if ((create_tag_object || force) && (cmdmode != 0))
 		usage_with_options(git_tag_usage, options);
 
@@ -483,7 +465,7 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 			run_column_filter(colopts, &copts);
 		}
 		filter.name_patterns = argv;
-		ret = list_tags(&filter, sorting, format);
+		ret = list_tags(&filter, sorting, &format);
 		if (column_active(colopts))
 			stop_column_filter();
 		return ret;
@@ -501,9 +483,9 @@ int cmd_tag(int argc, const char **argv, const char *prefix)
 	if (cmdmode == 'd')
 		return for_each_tag_name(argv, delete_tag, NULL);
 	if (cmdmode == 'v') {
-		if (format)
-			verify_ref_format(format);
-		return for_each_tag_name(argv, verify_tag, format);
+		if (format.format && verify_ref_format(&format))
+			usage_with_options(git_tag_usage, options);
+		return for_each_tag_name(argv, verify_tag, &format);
 	}
 
 	if (msg.given || msgfile) {
diff --git a/builtin/unpack-file.c b/builtin/unpack-file.c
index 73f1334191..281ca1db6c 100644
--- a/builtin/unpack-file.c
+++ b/builtin/unpack-file.c
@@ -1,7 +1,7 @@
 #include "builtin.h"
 #include "config.h"
 
-static char *create_temp_file(unsigned char *sha1)
+static char *create_temp_file(struct object_id *oid)
 {
 	static char path[50];
 	void *buf;
@@ -9,9 +9,9 @@ static char *create_temp_file(unsigned char *sha1)
 	unsigned long size;
 	int fd;
 
-	buf = read_sha1_file(sha1, &type, &size);
+	buf = read_sha1_file(oid->hash, &type, &size);
 	if (!buf || type != OBJ_BLOB)
-		die("unable to read blob object %s", sha1_to_hex(sha1));
+		die("unable to read blob object %s", oid_to_hex(oid));
 
 	xsnprintf(path, sizeof(path), ".merge_file_XXXXXX");
 	fd = xmkstemp(path);
@@ -23,15 +23,15 @@ static char *create_temp_file(unsigned char *sha1)
 
 int cmd_unpack_file(int argc, const char **argv, const char *prefix)
 {
-	unsigned char sha1[20];
+	struct object_id oid;
 
 	if (argc != 2 || !strcmp(argv[1], "-h"))
 		usage("git unpack-file <sha1>");
-	if (get_sha1(argv[1], sha1))
+	if (get_oid(argv[1], &oid))
 		die("Not a valid object name %s", argv[1]);
 
 	git_config(git_default_config, NULL);
 
-	puts(create_temp_file(sha1));
+	puts(create_temp_file(&oid));
 	return 0;
 }
diff --git a/builtin/update-ref.c b/builtin/update-ref.c
index 40ccfc193b..6b90c5dead 100644
--- a/builtin/update-ref.c
+++ b/builtin/update-ref.c
@@ -94,10 +94,10 @@ static char *parse_refname(struct strbuf *input, const char **next)
  * provided but cannot be converted to a SHA-1, die.  flags can
  * include PARSE_SHA1_OLD and/or PARSE_SHA1_ALLOW_EMPTY.
  */
-static int parse_next_sha1(struct strbuf *input, const char **next,
-			   unsigned char *sha1,
-			   const char *command, const char *refname,
-			   int flags)
+static int parse_next_oid(struct strbuf *input, const char **next,
+			  struct object_id *oid,
+			  const char *command, const char *refname,
+			  int flags)
 {
 	struct strbuf arg = STRBUF_INIT;
 	int ret = 0;
@@ -115,11 +115,11 @@ static int parse_next_sha1(struct strbuf *input, const char **next,
 		(*next)++;
 		*next = parse_arg(*next, &arg);
 		if (arg.len) {
-			if (get_sha1(arg.buf, sha1))
+			if (get_oid(arg.buf, oid))
 				goto invalid;
 		} else {
 			/* Without -z, an empty value means all zeros: */
-			hashclr(sha1);
+			oidclr(oid);
 		}
 	} else {
 		/* With -z, read the next NUL-terminated line */
@@ -133,13 +133,13 @@ static int parse_next_sha1(struct strbuf *input, const char **next,
 		*next += arg.len;
 
 		if (arg.len) {
-			if (get_sha1(arg.buf, sha1))
+			if (get_oid(arg.buf, oid))
 				goto invalid;
 		} else if (flags & PARSE_SHA1_ALLOW_EMPTY) {
 			/* With -z, treat an empty value as all zeros: */
 			warning("%s %s: missing <newvalue>, treating as zero",
 				command, refname);
-			hashclr(sha1);
+			oidclr(oid);
 		} else {
 			/*
 			 * With -z, an empty non-required value means
@@ -182,26 +182,25 @@ static const char *parse_cmd_update(struct ref_transaction *transaction,
 {
 	struct strbuf err = STRBUF_INIT;
 	char *refname;
-	unsigned char new_sha1[20];
-	unsigned char old_sha1[20];
+	struct object_id new_oid, old_oid;
 	int have_old;
 
 	refname = parse_refname(input, &next);
 	if (!refname)
 		die("update: missing <ref>");
 
-	if (parse_next_sha1(input, &next, new_sha1, "update", refname,
-			    PARSE_SHA1_ALLOW_EMPTY))
+	if (parse_next_oid(input, &next, &new_oid, "update", refname,
+			   PARSE_SHA1_ALLOW_EMPTY))
 		die("update %s: missing <newvalue>", refname);
 
-	have_old = !parse_next_sha1(input, &next, old_sha1, "update", refname,
-				    PARSE_SHA1_OLD);
+	have_old = !parse_next_oid(input, &next, &old_oid, "update", refname,
+				   PARSE_SHA1_OLD);
 
 	if (*next != line_termination)
 		die("update %s: extra input: %s", refname, next);
 
 	if (ref_transaction_update(transaction, refname,
-				   new_sha1, have_old ? old_sha1 : NULL,
+				   new_oid.hash, have_old ? old_oid.hash : NULL,
 				   update_flags | create_reflog_flag,
 				   msg, &err))
 		die("%s", err.buf);
@@ -218,22 +217,22 @@ static const char *parse_cmd_create(struct ref_transaction *transaction,
 {
 	struct strbuf err = STRBUF_INIT;
 	char *refname;
-	unsigned char new_sha1[20];
+	struct object_id new_oid;
 
 	refname = parse_refname(input, &next);
 	if (!refname)
 		die("create: missing <ref>");
 
-	if (parse_next_sha1(input, &next, new_sha1, "create", refname, 0))
+	if (parse_next_oid(input, &next, &new_oid, "create", refname, 0))
 		die("create %s: missing <newvalue>", refname);
 
-	if (is_null_sha1(new_sha1))
+	if (is_null_oid(&new_oid))
 		die("create %s: zero <newvalue>", refname);
 
 	if (*next != line_termination)
 		die("create %s: extra input: %s", refname, next);
 
-	if (ref_transaction_create(transaction, refname, new_sha1,
+	if (ref_transaction_create(transaction, refname, new_oid.hash,
 				   update_flags | create_reflog_flag,
 				   msg, &err))
 		die("%s", err.buf);
@@ -250,18 +249,18 @@ static const char *parse_cmd_delete(struct ref_transaction *transaction,
 {
 	struct strbuf err = STRBUF_INIT;
 	char *refname;
-	unsigned char old_sha1[20];
+	struct object_id old_oid;
 	int have_old;
 
 	refname = parse_refname(input, &next);
 	if (!refname)
 		die("delete: missing <ref>");
 
-	if (parse_next_sha1(input, &next, old_sha1, "delete", refname,
-			    PARSE_SHA1_OLD)) {
+	if (parse_next_oid(input, &next, &old_oid, "delete", refname,
+			   PARSE_SHA1_OLD)) {
 		have_old = 0;
 	} else {
-		if (is_null_sha1(old_sha1))
+		if (is_null_oid(&old_oid))
 			die("delete %s: zero <oldvalue>", refname);
 		have_old = 1;
 	}
@@ -270,7 +269,7 @@ static const char *parse_cmd_delete(struct ref_transaction *transaction,
 		die("delete %s: extra input: %s", refname, next);
 
 	if (ref_transaction_delete(transaction, refname,
-				   have_old ? old_sha1 : NULL,
+				   have_old ? old_oid.hash : NULL,
 				   update_flags, msg, &err))
 		die("%s", err.buf);
 
@@ -286,20 +285,20 @@ static const char *parse_cmd_verify(struct ref_transaction *transaction,
 {
 	struct strbuf err = STRBUF_INIT;
 	char *refname;
-	unsigned char old_sha1[20];
+	struct object_id old_oid;
 
 	refname = parse_refname(input, &next);
 	if (!refname)
 		die("verify: missing <ref>");
 
-	if (parse_next_sha1(input, &next, old_sha1, "verify", refname,
-			    PARSE_SHA1_OLD))
-		hashclr(old_sha1);
+	if (parse_next_oid(input, &next, &old_oid, "verify", refname,
+			   PARSE_SHA1_OLD))
+		oidclr(&old_oid);
 
 	if (*next != line_termination)
 		die("verify %s: extra input: %s", refname, next);
 
-	if (ref_transaction_verify(transaction, refname, old_sha1,
+	if (ref_transaction_verify(transaction, refname, old_oid.hash,
 				   update_flags, &err))
 		die("%s", err.buf);
 
@@ -355,7 +354,7 @@ static void update_refs_stdin(struct ref_transaction *transaction)
 int cmd_update_ref(int argc, const char **argv, const char *prefix)
 {
 	const char *refname, *oldval;
-	unsigned char sha1[20], oldsha1[20];
+	struct object_id oid, oldoid;
 	int delete = 0, no_deref = 0, read_stdin = 0, end_null = 0;
 	unsigned int flags = 0;
 	int create_reflog = 0;
@@ -412,7 +411,7 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 		refname = argv[0];
 		value = argv[1];
 		oldval = argv[2];
-		if (get_sha1(value, sha1))
+		if (get_oid(value, &oid))
 			die("%s: not a valid SHA1", value);
 	}
 
@@ -422,8 +421,8 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 			 * The empty string implies that the reference
 			 * must not already exist:
 			 */
-			hashclr(oldsha1);
-		else if (get_sha1(oldval, oldsha1))
+			oidclr(&oldoid);
+		else if (get_oid(oldval, &oldoid))
 			die("%s: not a valid old SHA1", oldval);
 	}
 
@@ -435,10 +434,10 @@ int cmd_update_ref(int argc, const char **argv, const char *prefix)
 		 * NULL_SHA1 as "don't care" here:
 		 */
 		return delete_ref(msg, refname,
-				  (oldval && !is_null_sha1(oldsha1)) ? oldsha1 : NULL,
+				  (oldval && !is_null_oid(&oldoid)) ? oldoid.hash : NULL,
 				  flags);
 	else
-		return update_ref(msg, refname, sha1, oldval ? oldsha1 : NULL,
+		return update_ref(msg, refname, oid.hash, oldval ? oldoid.hash : NULL,
 				  flags | create_reflog_flag,
 				  UPDATE_REFS_DIE_ON_ERR);
 }
diff --git a/builtin/verify-tag.c b/builtin/verify-tag.c
index f9a5f7535a..ad7b79fa5c 100644
--- a/builtin/verify-tag.c
+++ b/builtin/verify-tag.c
@@ -32,11 +32,11 @@ int cmd_verify_tag(int argc, const char **argv, const char *prefix)
 {
 	int i = 1, verbose = 0, had_error = 0;
 	unsigned flags = 0;
-	char *fmt_pretty = NULL;
+	struct ref_format format = REF_FORMAT_INIT;
 	const struct option verify_tag_options[] = {
 		OPT__VERBOSE(&verbose, N_("print tag contents")),
 		OPT_BIT(0, "raw", &flags, N_("print raw gpg status output"), GPG_VERIFY_RAW),
-		OPT_STRING(  0 , "format", &fmt_pretty, N_("format"), N_("format to use for the output")),
+		OPT_STRING(0, "format", &format.format, N_("format"), N_("format to use for the output")),
 		OPT_END()
 	};
 
@@ -50,26 +50,29 @@ int cmd_verify_tag(int argc, const char **argv, const char *prefix)
 	if (verbose)
 		flags |= GPG_VERIFY_VERBOSE;
 
-	if (fmt_pretty) {
-		verify_ref_format(fmt_pretty);
+	if (format.format) {
+		if (verify_ref_format(&format))
+			usage_with_options(verify_tag_usage,
+					   verify_tag_options);
 		flags |= GPG_VERIFY_OMIT_STATUS;
 	}
 
 	while (i < argc) {
-		unsigned char sha1[20];
+		struct object_id oid;
 		const char *name = argv[i++];
-		if (get_sha1(name, sha1)) {
+
+		if (get_oid(name, &oid)) {
 			had_error = !!error("tag '%s' not found.", name);
 			continue;
 		}
 
-		if (gpg_verify_tag(sha1, name, flags)) {
+		if (gpg_verify_tag(&oid, name, flags)) {
 			had_error = 1;
 			continue;
 		}
 
-		if (fmt_pretty)
-			pretty_print_ref(name, sha1, fmt_pretty);
+		if (format.format)
+			pretty_print_ref(name, oid.hash, &format);
 	}
 	return had_error;
 }