Merge branch 'ep/maint-equals-null-cocci'

Introduce and apply coccinelle rule to discourage an explicit
comparison between a pointer and NULL, and applies the clean-up to
the maintenance track.

* ep/maint-equals-null-cocci:
  tree-wide: apply equals-null.cocci
  tree-wide: apply equals-null.cocci
  contrib/coccinnelle: add equals-null.cocci

Author: gitster

apply.c

@@ -3274,11 +3274,11 @@ static struct patch *in_fn_table(struct apply_state *state, const char *name)
 {
 	struct string_list_item *item;
 
-	if (name == NULL)
+	if (!name)
 		return NULL;
 
 	item = string_list_lookup(&state->fn_table, name);
-	if (item != NULL)
+	if (item)
 		return (struct patch *)item->util;
 
 	return NULL;
@@ -3318,7 +3318,7 @@ static void add_to_fn_table(struct apply_state *state, struct patch *patch)
 	 * This should cover the cases for normal diffs,
 	 * file creations and copies
 	 */
-	if (patch->new_name != NULL) {
+	if (patch->new_name) {
 		item = string_list_insert(&state->fn_table, patch->new_name);
 		item->util = patch;
 	}

archive.c

@@ -465,7 +465,7 @@ static void parse_treeish_arg(const char **argv,
 	}
 
 	tree = parse_tree_indirect(&oid);
-	if (tree == NULL)
+	if (!tree)
 		die(_("not a tree object: %s"), oid_to_hex(&oid));
 
 	if (prefix) {

blame.c

@@ -1072,7 +1072,7 @@ static struct blame_entry *blame_merge(struct blame_entry *list1,
 	if (p1->s_lno <= p2->s_lno) {
 		do {
 			tail = &p1->next;
-			if ((p1 = *tail) == NULL) {
+			if (!(p1 = *tail)) {
 				*tail = p2;
 				return list1;
 			}
@@ -1082,15 +1082,15 @@ static struct blame_entry *blame_merge(struct blame_entry *list1,
 		*tail = p2;
 		do {
 			tail = &p2->next;
-			if ((p2 = *tail) == NULL)  {
+			if (!(p2 = *tail))  {
 				*tail = p1;
 				return list1;
 			}
 		} while (p1->s_lno > p2->s_lno);
 		*tail = p1;
 		do {
 			tail = &p1->next;
-			if ((p1 = *tail) == NULL) {
+			if (!(p1 = *tail)) {
 				*tail = p2;
 				return list1;
 			}

branch.c

@@ -466,7 +466,7 @@ static void dwim_branch_start(struct repository *r, const char *start_name,
 		break;
 	}
 
-	if ((commit = lookup_commit_reference(r, &oid)) == NULL)
+	if (!(commit = lookup_commit_reference(r, &oid)))
 		die(_("not a valid branch point: '%s'"), start_name);
 	if (out_real_ref) {
 		*out_real_ref = real_ref;

builtin/bisect--helper.c

@@ -474,7 +474,7 @@ static int bisect_terms(struct bisect_terms *terms, const char *option)
 	if (get_terms(terms))
 		return error(_("no terms defined"));
 
-	if (option == NULL) {
+	if (!option) {
 		printf(_("Your current terms are %s for the old state\n"
 			 "and %s for the new state.\n"),
 		       terms->term_good, terms->term_bad);

builtin/checkout.c

@@ -834,7 +834,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			if (ret)
 				return ret;
 			o.ancestor = old_branch_info->name;
-			if (old_branch_info->name == NULL) {
+			if (!old_branch_info->name) {
 				strbuf_add_unique_abbrev(&old_commit_shortname,
 							 &old_branch_info->commit->object.oid,
 							 DEFAULT_ABBREV);

builtin/clone.c

@@ -1106,12 +1106,12 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	 * apply the remote name provided by --origin only after this second
 	 * call to git_config, to ensure it overrides all config-based values.
 	 */
-	if (option_origin != NULL) {
+	if (option_origin) {
 		free(remote_name);
 		remote_name = xstrdup(option_origin);
 	}
 
-	if (remote_name == NULL)
+	if (!remote_name)
 		remote_name = xstrdup("origin");
 
 	if (!valid_remote_name(remote_name))

builtin/commit.c

@@ -861,7 +861,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 	}
 
 	s->fp = fopen_for_writing(git_path_commit_editmsg());
-	if (s->fp == NULL)
+	if (!s->fp)
 		die_errno(_("could not open '%s'"), git_path_commit_editmsg());
 
 	/* Ignore status.displayCommentPrefix: we do need comments in COMMIT_EDITMSG. */

builtin/diff.c

@@ -352,7 +352,7 @@ static void symdiff_prepare(struct rev_info *rev, struct symdiff *sym)
 			othercount++;
 			continue;
 		}
-		if (map == NULL)
+		if (!map)
 			map = bitmap_new();
 		bitmap_set(map, i);
 	}

builtin/gc.c

@@ -446,7 +446,7 @@ static const char *lock_repo_for_gc(int force, pid_t* ret_pid)
 			fscanf(fp, scan_fmt, &pid, locking_host) == 2 &&
 			/* be gentle to concurrent "gc" on remote hosts */
 			(strcmp(locking_host, my_host) || !kill(pid, 0) || errno == EPERM);
-		if (fp != NULL)
+		if (fp)
 			fclose(fp);
 		if (should_exit) {
 			if (fd >= 0)
@@ -2238,7 +2238,7 @@ static int systemd_timer_write_unit_templates(const char *exec_path)
 		goto error;
 	}
 	file = fopen_or_warn(filename, "w");
-	if (file == NULL)
+	if (!file)
 		goto error;
 
 	unit = "# This file was created and is maintained by Git.\n"
@@ -2267,7 +2267,7 @@ static int systemd_timer_write_unit_templates(const char *exec_path)
 
 	filename = xdg_config_home_systemd("[email protected]");
 	file = fopen_or_warn(filename, "w");
-	if (file == NULL)
+	if (!file)
 		goto error;
 
 	unit = "# This file was created and is maintained by Git.\n"