Fix various sparse warnings in the git source code

There are a few remaining ones, but this fixes the trivial ones. It boils
down to two main issues that sparse complains about:

 - warning: Using plain integer as NULL pointer

   Sparse doesn't like you using '0' instead of 'NULL'. For various good
   reasons, not the least of which is just the visual confusion. A NULL
   pointer is not an integer, and that whole "0 works as NULL" is a
   historical accident and not very pretty.

   A few of these remain: zlib is a total mess, and Z_NULL is just a 0.
   I didn't touch those.

 - warning: symbol 'xyz' was not declared. Should it be static?

   Sparse wants to see declarations for any functions you export. A lack
   of a declaration tends to mean that you should either add one, or you
   should mark the function 'static' to show that it's in file scope.

   A few of these remain: I only did the ones that should obviously just
   be made static.

That 'wt_status_submodule_summary' one is debatable. It has a few related
flags (like 'wt_status_use_color') which _are_ declared, and are used by
builtin-commit.c. So maybe we'd like to export it at some point, but it's
not declared now, and not used outside of that file, so 'static' it is in
this patch.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: torvalds

bisect.c

@@ -454,7 +454,7 @@ static int read_bisect_refs(void)
 	return for_each_ref_in("refs/bisect/", register_ref, NULL);
 }
 
-void read_bisect_paths(struct argv_array *array)
+static void read_bisect_paths(struct argv_array *array)
 {
 	struct strbuf str = STRBUF_INIT;
 	const char *filename = git_path("BISECT_NAMES");
@@ -780,7 +780,7 @@ static void handle_bad_merge_base(void)
 	exit(1);
 }
 
-void handle_skipped_merge_base(const unsigned char *mb)
+static void handle_skipped_merge_base(const unsigned char *mb)
 {
 	char *mb_hex = sha1_to_hex(mb);
 	char *bad_hex = sha1_to_hex(current_bad_sha1);

builtin-add.c

@@ -189,7 +189,7 @@ int interactive_add(int argc, const char **argv, const char *prefix)
 	return status;
 }
 
-int edit_patch(int argc, const char **argv, const char *prefix)
+static int edit_patch(int argc, const char **argv, const char *prefix)
 {
 	char *file = xstrdup(git_path("ADD_EDIT.patch"));
 	const char *apply_argv[] = { "apply", "--recount", "--cached",

builtin-apply.c

@@ -2614,7 +2614,7 @@ static int get_current_sha1(const char *path, unsigned char *sha1)
 static void build_fake_ancestor(struct patch *list, const char *filename)
 {
 	struct patch *patch;
-	struct index_state result = { 0 };
+	struct index_state result = { NULL };
 	int fd;
 
 	/* Once we start supporting the reverse patch, it may be

builtin-clone.c

@@ -141,7 +141,7 @@ static char *guess_dir_name(const char *repo, int is_bundle, int is_bare)
 	if (is_bare) {
 		struct strbuf result = STRBUF_INIT;
 		strbuf_addf(&result, "%.*s.git", (int)(end - start), start);
-		dir = strbuf_detach(&result, 0);
+		dir = strbuf_detach(&result, NULL);
 	} else
 		dir = xstrndup(start, end - start);
 	/*

builtin-fsck.c

@@ -104,7 +104,7 @@ static int mark_object(struct object *obj, int type, void *data)
 
 static void mark_object_reachable(struct object *obj)
 {
-	mark_object(obj, OBJ_ANY, 0);
+	mark_object(obj, OBJ_ANY, NULL);
 }
 
 static int traverse_one_object(struct object *obj, struct object *parent)
@@ -292,7 +292,7 @@ static int fsck_sha1(const unsigned char *sha1)
 		fprintf(stderr, "Checking %s %s\n",
 			typename(obj->type), sha1_to_hex(obj->sha1));
 
-	if (fsck_walk(obj, mark_used, 0))
+	if (fsck_walk(obj, mark_used, NULL))
 		objerror(obj, "broken links");
 	if (fsck_object(obj, check_strict, fsck_error_func))
 		return -1;

builtin-help.c

@@ -394,7 +394,7 @@ static void get_html_page_path(struct strbuf *page_path, const char *page)
  * HTML.
  */
 #ifndef open_html
-void open_html(const char *path)
+static void open_html(const char *path)
 {
 	execl_git_cmd("web--browse", "-c", "help.browser", path, NULL);
 }

builtin-log.c

@@ -94,7 +94,7 @@ static void show_early_header(struct rev_info *rev, const char *stage, int nr)
 	printf("Final output: %d %s\n", nr, stage);
 }
 
-struct itimerval early_output_timer;
+static struct itimerval early_output_timer;
 
 static void log_show_early(struct rev_info *revs, struct commit_list *list)
 {
@@ -977,7 +977,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		strbuf_addch(&buf, '\n');
 	}
 
-	rev.extra_headers = strbuf_detach(&buf, 0);
+	rev.extra_headers = strbuf_detach(&buf, NULL);
 
 	if (start_number < 0)
 		start_number = 1;

builtin-merge.c

@@ -370,7 +370,7 @@ static void merge_name(const char *remote, struct strbuf *msg)
 
 	strbuf_addstr(&buf, "refs/heads/");
 	strbuf_addstr(&buf, remote);
-	resolve_ref(buf.buf, branch_head, 0, 0);
+	resolve_ref(buf.buf, branch_head, 0, NULL);
 
 	if (!hashcmp(remote_head->sha1, branch_head)) {
 		strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
@@ -409,7 +409,7 @@ 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, 0, 0)) {
+		if (resolve_ref(truname.buf, buf_sha, 0, NULL)) {
 			strbuf_addf(msg,
 				    "%s\t\tbranch '%s'%s of .\n",
 				    sha1_to_hex(remote_head->sha1),

builtin-remote.c

@@ -740,7 +740,7 @@ static int rm(int argc, const char **argv)
 	return result;
 }
 
-void clear_push_info(void *util, const char *string)
+static void clear_push_info(void *util, const char *string)
 {
 	struct push_info *info = util;
 	free(info->dest);
@@ -815,7 +815,7 @@ struct show_info {
 	int any_rebase;
 };
 
-int add_remote_to_show_info(struct string_list_item *item, void *cb_data)
+static int add_remote_to_show_info(struct string_list_item *item, void *cb_data)
 {
 	struct show_info *info = cb_data;
 	int n = strlen(item->string);
@@ -825,7 +825,7 @@ int add_remote_to_show_info(struct string_list_item *item, void *cb_data)
 	return 0;
 }
 
-int show_remote_info_item(struct string_list_item *item, void *cb_data)
+static int show_remote_info_item(struct string_list_item *item, void *cb_data)
 {
 	struct show_info *info = cb_data;
 	struct ref_states *states = info->states;
@@ -852,7 +852,7 @@ int show_remote_info_item(struct string_list_item *item, void *cb_data)
 	return 0;
 }
 
-int add_local_to_show_info(struct string_list_item *branch_item, void *cb_data)
+static int add_local_to_show_info(struct string_list_item *branch_item, void *cb_data)
 {
 	struct show_info *show_info = cb_data;
 	struct ref_states *states = show_info->states;
@@ -874,7 +874,7 @@ int add_local_to_show_info(struct string_list_item *branch_item, void *cb_data)
 	return 0;
 }
 
-int show_local_info_item(struct string_list_item *item, void *cb_data)
+static int show_local_info_item(struct string_list_item *item, void *cb_data)
 {
 	struct show_info *show_info = cb_data;
 	struct branch_info *branch_info = item->util;
@@ -906,7 +906,7 @@ int show_local_info_item(struct string_list_item *item, void *cb_data)
 	return 0;
 }
 
-int add_push_to_show_info(struct string_list_item *push_item, void *cb_data)
+static int add_push_to_show_info(struct string_list_item *push_item, void *cb_data)
 {
 	struct show_info *show_info = cb_data;
 	struct push_info *push_info = push_item->util;
@@ -935,7 +935,7 @@ static int cmp_string_with_push(const void *va, const void *vb)
 	return cmp ? cmp : strcmp(a_push->dest, b_push->dest);
 }
 
-int show_push_info_item(struct string_list_item *item, void *cb_data)
+static int show_push_info_item(struct string_list_item *item, void *cb_data)
 {
 	struct show_info *show_info = cb_data;
 	struct push_info *push_info = item->util;
@@ -1197,7 +1197,7 @@ static int get_one_remote_for_update(struct remote *remote, void *priv)
 	return 0;
 }
 
-struct remote_group {
+static struct remote_group {
 	const char *name;
 	struct string_list *list;
 } remote_group;

builtin-unpack-objects.c

@@ -158,7 +158,7 @@ struct obj_info {
 #define FLAG_WRITTEN (1u<<21)
 
 static struct obj_info *obj_list;
-unsigned nr_objects;
+static unsigned nr_objects;
 
 /*
  * Called only from check_object() after it verified this object
@@ -200,7 +200,7 @@ static int check_object(struct object *obj, int type, void *data)
 
 	if (fsck_object(obj, 1, fsck_error_function))
 		die("Error in object");
-	if (!fsck_walk(obj, check_object, 0))
+	if (!fsck_walk(obj, check_object, NULL))
 		die("Error on reachable objects of %s", sha1_to_hex(obj->sha1));
 	write_cached_object(obj);
 	return 1;
@@ -210,7 +210,7 @@ static void write_rest(void)
 {
 	unsigned i;
 	for (i = 0; i < nr_objects; i++)
-		check_object(obj_list[i].obj, OBJ_ANY, 0);
+		check_object(obj_list[i].obj, OBJ_ANY, NULL);
 }
 
 static void added_object(unsigned nr, enum object_type type,